HomeMy WebLinkAbout05.28.26 Board Correspondence - FW_ TWSD 2025 UWMP Draft Update.ATTENTION: This message originated from outside Butte County. Please exercise judgment before opening
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From:Clerk of the Board
To:Clerk of the Board; Connelly, Bill; Cook, Holly; Cook, Robin; Durfee, Peter; Jessee, Meegan; Kimmelshue, Tod;
Kitts, Melissa; Krater, Sharleen; Lee, Lewis; Little, Melissa; Pickett, Andy; Ritter, Tami; Stephens, Brad J.;
Sweeney, Kathleen; Teeter, Doug; Zepeda, Elizabeth
Cc:Cannon, Jamie
Subject:Board Correspondence - FW: TWSD 2025 UWMP Draft Update
Date:Thursday, May 28, 2026 1:07:16 PM
Attachments:2025 TWSD UWMP-Draft.pdf
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Please see Board Correspondence -
Lewis LeeAdministrative Technician - ConfidentialButte County Administration25 County Center Drive, Suite 200 • Oroville, CA 95965T: 530.552.3326www.buttecounty.ca.gov | lelee@buttecounty.ca.gov
From: Loeser, Kamie <KLoeser@buttecounty.ca.gov>
Sent: Thursday, May 28, 2026 7:12 AM
To: Clerk of the Board <clerkoftheboard@buttecounty.ca.gov>
Subject: Fw: TWSD 2025 UWMP Draft Update
Sharing this notice.
Sent from Kamie's phone, please excuse brevity and typos.
From: Chris Heindell <Cheindell@twsd.info>
Sent: Wednesday, May 27, 2026 2:38:35 PM
To: Loeser, Kamie <KLoeser@buttecounty.ca.gov>; Tim Kaber <tkaber@cityoforoville.org>
Cc: BCWater <BCWaterFrontDeskHG@buttecounty.ca.gov>
Subject: TWSD 2025 UWMP Draft Update
Good afternoon,
Attached is the 2025 Draft UWMP update for TWSD. As mentioned in the notice, the public
hearing for this document will be at our July 21, 2026 board meeting. If you have any questions
or comments, please let me know.
Best Regards,
Chris Heindell, P.E.
Thermalito Water and Sewer District
410 Grand Avenue
Oroville, CA 95965
(530) 533-0740
www.TWSD.info
2025 Urban Water Management
Plan
Jayme Boucher, General Manager
Thermalito Water and Sewer District
410 Grand Avenue
Oroville, California 95965
June 2026
2025 Urban Water Management Plan
Submitted By:
Jayme Boucher, General Manager
Thermalito Water and Sewer District 410 Grand Avenue
Oroville, California 95965
Prepared by:
Chris Heindell
410 Grand Avenue
Oroville, CA 95965
Contributors:
Jayme Boucher, General Manager
Chris Heindell, P.E., District Engineer
Board of Directors:
Mark Clark, President
Bruce Wristen, Vice President
Scott Koch, Director
Art Hatley, Director
Brad Taggart, Director
THERMALITO WATER AND SEWER DISTRICT
2025 URBAN WATER MANAGEMENT PLAN
Date plan submitted to the Department of Water Resources: June 20, 2026
Name of person preparing this plan: Jayme Boucher, General Manager
Phone: (530) 533-0740
Fax: (530) 533-9243
E-mail address: jboucher@twsd.info
The Water supplier is a Public Agency formed pursuant to Water Code § 20500 et seq. (formerly Thermalito Irrigation
District).
The Water supplier is a: Retailer
Utility services provided by the water supplier include domestic and irrigation water service, and
sewer collection.
Is This Agency a Bureau of Reclamation Contractor? No
Is This Agency a State Water Project Contractor? No
Page Intentionally Left Blank.
Table of Contents
CHAPTER 1 ‐ INTRODUCTION AND LAY DESCRIPTION ....................................................................................... 1
CHAPTER 2 ‐ PLAN PREPARATION ................................................................................................................... 3
2.2 Plan Preparation ............................................................................................................................................... 3
2.2 Basis for Preparing a Plan ................................................................................................................................. 3
2.2.1 Public Water Systems ................................................................................................................................ 4
2.2.2 Agencies Serving Multiple Service Areas/Public Water Systems .............................................................. 4
2.3 Regional Planning ............................................................................................................................................. 5
2.4 Individual or Regional Planning and Compliance ............................................................................................. 5
2.4.1 Regional UWMP ........................................................................................................................................ 6
2.4.2 Regional Alliance ....................................................................................................................................... 6
2.5 Fiscal or Calendar Year and Units of Measure .................................................................................................. 7
2.5.1 Fiscal or Calendar Year .............................................................................................................................. 7
2.5.2 Reporting Complete 2020 Data ................................................................................................................. 8
2.5.3 Units of Measure ....................................................................................................................................... 8
2.6 Coordination and Outreach .............................................................................................................................. 8
2.6.1 Wholesale and Retail Coordination ........................................................................................................... 8
2.6.2 Coordination Other Agencies and the Community ................................................................................... 8
2.6.3 Notice to Cities and Counties .................................................................................................................... 9
CHAPTER 3 ‐ SYSTEM DESCRIPTION ............................................................................................................... 11
3.1 General Description ........................................................................................................................................ 11
3.2 Service Area Boundary Map ........................................................................................................................... 13
3.3 Service Area Climate ....................................................................................................................................... 13
3.4 Service Area Population, Demographics, and Socioeconomics ...................................................................... 14
3.4.1 Service Area Population .......................................................................................................................... 14
3.4.2 Other Social, Economic, and Demographic Factors ................................................................................ 15
3.5 Land Uses within Service Area ........................................................................................................................ 16
CHAPTER 4 – WATER USE CHARACTERIZATION .............................................................................................. 17
4.1 Non-Potable vs. Potable Water Use ............................................................................................................... 17
4.2 Past, Current, and Projected Water Use by Sector ........................................................................................ 17
4.2.1 Water Use Sectors Listed in Water Code ................................................................................................ 17
4.2.2 Past Water Use ........................................................................................................................................ 18
4.2.3 Current Water Use .................................................................................................................................. 18
4.2.4 Projected Water Use ............................................................................................................................... 19
4.2.5 Distribution System Water Loss .............................................................................................................. 22
4.3 Water Use for Lower Income Households ...................................................................................................... 23
4.4 Climate Change Considerations ...................................................................................................................... 24
CHAPTER 5 – SBX7‐7 BASELINES, TARGETS, AND 2025 REPORTING ................................................................. 26
5.1 Baseline and Target Calculations for 2025 UWMPs ....................................................................................... 26
5.2 Methods for Calculating Population and Gross Water Use ............................................................................ 27
5.2.1 Department of Finance ........................................................................................................................... 27
5.2.2 Gross Water Use ...................................................................................................................................... 27
5.3 2020 Compliance Daily Per-Capita Water Use (GPCD) ................................................................................... 27
5.3.4 2020 Adjustments for Factors Outside of Supplier’s Control .................................................................. 28
5.3.5 If Supplier Does Not Meet 2020 Target................................................................................................... 28
CHAPTER 6 – WATER SUPPLY CHARACTERIZATION ......................................................................................... 29
6.1 Water Supply Analysis Overview .................................................................................................................... 29
6.2 Supplier’s UWMP Water Supply Characterization .......................................................................................... 30
6.2.1 Purchased or Imported Water ................................................................................................................ 30
6.2.2 Groundwater ........................................................................................................................................... 30
6.2.3 Surface Water .......................................................................................................................................... 31
6.2.4 Stormwater .............................................................................................................................................. 32
6.2.5 Wastewater and Recycled Water ............................................................................................................ 32
6.2.6 Desalinated Water ................................................................................................................................... 34
6.2.7 Water Exchanges and Transfers .............................................................................................................. 34
6.2.8 Future Water Projects ............................................................................................................................. 34
6.2.9 Summary of Existing and Planned Sources of Water .............................................................................. 35
6.3 Energy Use ...................................................................................................................................................... 38
CHAPTER 7 – WATER SERVICE RELIABILITY AND DROUGHT RISK ASSESSMENT ............................................... 40
7.1 Water Service Reliability ................................................................................................................................. 40
7.2 Supply and Demand ....................................................................................................................................... 42
7.3 Drought Risk Assessment ............................................................................................................................... 45
CHAPTER 8 ‐ WATER SHORTAGE CONTINGENCY PLANNING ............................................................................ 47
8.1 Water Supply Reliability Analysis ................................................................................................................... 47
8.2 Annual Water Supply and Demand Assessment Procedures ......................................................................... 48
8.3 Six Standard Water Shortage Stages .............................................................................................................. 49
8.4 Shortage Response Actions ............................................................................................................................ 51
8.4.1 Supply Augmentation.............................................................................................................................. 51
8.4.2 Demand Augmentation ........................................................................................................................... 52
8.4.3 Supply Augmentation .............................................................................................................................. 54
8.4.4 Operational Enhancements ..................................................................................................................... 54
8.4.5 Rationing Stages to Address Water Supply Shortages ............................................................................ 54
8.4.6 Emergency Response .............................................................................................................................. 55
8.4.7 Seismic Risk Assessment and Mitigation Plan ......................................................................................... 56
8.5 Communication Protocols .............................................................................................................................. 57
8.6 Compliance and Enforcement ........................................................................................................................ 57
8.7 Legal Authorities ............................................................................................................................................. 57
8.8 Financial Consequences of WSCP Activation .................................................................................................. 58
8.9 Monitoring and Reporting .............................................................................................................................. 58
8.10 WSCP Refinement Procedures ................................................................................................................ 58
8.11 Special Water Feature Distinction ........................................................................................................... 59
8.12 Plan Adoption, Submittal, and availability ............................................................................................... 59
CHAPTER 9 – DEMAND MANAGEMENT MEASURES ........................................................................................ 60
9.1 Demand Management Measures for Retail Suppliers ................................................................................... 60
9.1.1 Metering .................................................................................................................................................. 60
9.1.2 Public Education and Outreach ............................................................................................................... 61
9.1.3 Water Conservation Program Coordination and Staffing Support ......................................................... 61
9.1.4 Water Waste Prevention Ordinances ...................................................................................................... 61
9.2 Reporting Implementation ............................................................................................................................. 62
9.2.1 Implementation to Achieve Water Use Targets ...................................................................................... 62
9.3 Water Use Objectives ..................................................................................................................................... 62
CHAPTER 10 ‐ PLAN ADOPTION, SUBMITTAL, AND IMPLEMENTATION ............................................................ 63
10.1 Inclusion of All 2025 Data ........................................................................................................................ 63
10.2 Notice of Public Hearing .......................................................................................................................... 63
10.2.1 Notice to Local Government .............................................................................................................. 63
10.2.2 Notice to the Public ............................................................................................................................ 64
10.3 Public Hearing and Adoption ................................................................................................................... 65
10.4 Plan Submittal ......................................................................................................................................... 65
10.4.1 Submitting the UWMP to DWR .......................................................................................................... 66
10.4.2 Submitting the UWMP to the CA State Library .................................................................................. 66
10.4.3 Submitting the UWMP to Cities and Counties ................................................................................... 66
10.5 Public Availability ..................................................................................................................................... 66
10.6 Notification to Public Utilities Commission ............................................................................................. 66
10.7 Amending an Adopted UWMP or Water Shortage Contingency Plan ..................................................... 67
FIGURE 1 – PROJECT LOCATION
LIST OF FIGURES
FIGURE 2 – SERVICE AREA AND SPHERE OF INFLUENCE
FIGURE 3 – WATER CONVEYANCE AND DISTRIBUTION SYSTEM
FIGURE 4 - AVERAGE MONTHLY TEMPERATURE AND AVERAGE MONTHLY RAINFALL TOTALS FROM
1953 TO 2005
FIGURE 5 – DISADVANTAGED COMMUNITIES - THERMALITO
APPENDICIES
APPENDIX A: WATER SHORTAGE CONTINGENCY PLAN
APPENDIX B: UWMP NOTICE
APPENDIX C: LOCAL HAZARD MITIGATION PLAN 2024
APPENDIX D: UWMP 2025 CHECKLIST
APPENDIX E: ADOPTION RESOLUTION
Page Intentionally Left Blank.
Page | 1
CHAPTER 1 ‐ INTRODUCTION AND LAY DESCRIPTION
This is the 2025 Urban Water Management Plan (UWMP) for the Thermalito Water and Sewer District
(District) which was organized in 1922 under the Irrigation Act (Water Code §§20500, et seq.) and
authorizing statues (Water Code §§22975, et seq.). The District was originally named the Thermalito
Irrigation District (TID) and provided only water service. Sanitary sewer collection and conveyance
services were added to the District in 1972 and in 2008, the District’s name was officially changed to
the Thermalito Water and Sewer District. The District serves a population of 12,434 people for
residential, municipal, recreational, industrial, and irrigation uses, as well as wastewater collection.
Approximately one-third of the District’s customers are within the City of Oroville city limits, with the
remainder in the unincorporated areas of Butte County. As such, the District is one of the few
California districts that provide a full complement of water-related services.
This UWMP has been prepared in accordance with the Urban Water Management Act (Act). The Act
is defined by the California Water Code, Division 6, Part 2.6, and §§10610 through §§10657. The Act
became part of the California Water Code (Code) with the passage of Assembly Bill 797 during the
1983-1984 regular session of the California legislature. The Act requires urban water suppliers
providing municipal water to more than 3,000 connections or supplying more than 3,000 acre-feet
(AF) of water annually to adopt and submit a plan every five years to the California Department of
Water Resources (DWR). Subsequent assembly bills have amended the Act. In complying with the
Act, the District has followed the DWR Urban Water Management Plan Guidebook 2025.
The District currently has 3,213 connections at the end of 2025. With more than 3,000 connections,
the District falls under the required UWMP five-year process. This UWMP is part of District’s long-
term resource planning efforts to ensure adequate water supplies are available to meet existing and
future water demands.
Water demands refer not only to the water used by customers, but also includes the water used as a
part of the system’s maintenance and operation, as well as unavoidable losses inherent in the
operation of a water distribution system. Water demand within the District was 2,115 AF on average
between 2020 and 2025. Taking into account historical water use, expected population increase and
other growth, climactic variability, and other assumptions, water demand within the District is
projected to be 2,223 AFY in 2030 and increase to 2,942 AFY by 2050. In dry year periods such as an
extended 5 year drought, water demands are expected to be up to 2,760 AFY by 2050.
The Water Conservation Act of 2009 (Senate Bill X7-7) was enacted in November 2009 and requires
the state of California to achieve a 20 percent reduction in urban per capita water use by December
31, 2020. In order to achieve this, each urban retail water supplier was required to establish water
use targets for 2020 using methodologies established by DWR. The Thermalito Water and Sewer
District achieved compliance with its 2020 water use target of 197 gallons per capita per day (GPCD),
with a reported water use in 2020 of 175 GPCD.
The TWSD derives its water from surface and well water sources. The District currently has no plans
of acquiring new sources of supply. The combination of surface and ground water supplies is expected
Page | 2
to be sufficient to support the Thermalito Water and Sewer District’s projected water demand
through 2050.
Calculating and reporting of water system energy intensity was a new requirement for the 2020 UWMP
and is included in the 2025 update as well. Energy intensity is defined as the net energy used for
water treatment, pumping, conveyance, and distribution for all water entering the distribution
system. The energy intensity for the TWSD is approximately 851 kilowatt hours per acre-foot of water
(kwh/AF); however, the District utilizes solar panels for self-generated renewable energy to offset the
energy intensity. The TWSD treatment plant utilized 635,852 kwh. Luckily, the solar power production
contributed 730,570 kwh on energy, bringing the net energy use to -94,718 kwh in 2025.
The intent of the water supply reliability assessment is to identify any potential constraints that could
affect the reliability of the District’s supply to support the District’s planning efforts to ensure that its
customers are well served. Water service reliability is assessed during normal, single dry-year, and
multiple dry-year hydrologic conditions. Based on this analysis, the Thermalito Water and Sewer
District expects the available supplies to be sufficient to meet projected demands in all hydrologic
conditions, including a five-year drought period, and considering the impacts of climate change.
Further, potential water quality is routinely monitored and the District is able to make all appropriate
adjustments to its treatment and distribution system to ensure only high quality water is served.
The Water Shortage Contingency Plan (WSCP) serves as a standalone document to be engaged in the
event of a water shortage such as drought or supply interruption. It defines specific policies and action
that will be implemented at various shortage level scenarios. For example, implementing customer
water budgets and surcharges, or restricting landscape irrigation to specific days and/or times.
Consistent with DWR requirements, the WSCP includes six levels to address shortage conditions
ranging from up to 10 percent to greater than 50 percent shortage.
Prior to adopting the UWMP, the District held a formal public hearing to present information on
its Thermalito Water And Sewer District UWMP and WCSP on July 21, 2026, at 2:00 PM. This UWMP
and corresponding WSCP were submitted to DWR within 30 days of adoption.
Page | 3
CHAPTER 2 ‐ PLAN PREPARATION
This Section provides information on how the UWMP was prepared, coordinated with other agencies
and the public, and adopted.
This section includes the following subsections:
2.1 Plan Preparation
2.2 Basis for Preparing a Plan
2.3 Regional Planning
2.4 Individual or Regional Planning and Compliance
2.5 Fiscal or Calendar Year and Units of Measure
2.6 Coordination and Outreach
2.2 Plan Preparation
This chapter provides the guidance for determining if a water supplier is required to prepare a UWMP
and describes the various levels of regional coordination that an agency may employ. It also includes
guidance and tables for two pieces of information to apply consistently throughout the UWMP: the
use of a fiscal calendar year, and the specific units of measure used by the supplier to report volumes.
This UWMP preparation and development was accomplished with the assistance and coordination
with District personnel, NorthStar, and the UWMP 2020 Guidebook.
2.2 Basis for Preparing a Plan
The basis for preparing a UWMP is identified in the Water Code:
Water Code Section 10617
“Urban water supplier” means a supplier, either publicly or privately owned, providing water for
municipal purposes either directly or indirectly to more than 3,000 customers or supplying more than
3,000 acre-feet of water annually. An urban water supplier includes a supplier or contractor for water,
regardless of the basis of right, which distributes or sells for ultimate resale to customers. This part
applies only to water supplied from public water systems.
Water Code Section 10620
(b)Every person that becomes an urban water supplier shall adopt an urban water management plan
within one year after it has become an urban water supplier.
Water Code Section 10620
(a) Each urban water supplier shall update its plan at least once every five years on or before July 1,
in years ending in six and one, incorporating updated and new information from the five years
preceding each update.
Thermalito Water and Sewer District (TWSD) qualifies as an Urban Water Supplier based on the
California Water Code definition of providing water to more than 3,000 customers. This 2025 Urban
Water Management Plan (UWMP) is being completed in 2026 as required by California Water Code
Page | 4
(CWC) 10621(f).
This plan document includes TWSD’s current supply calculations, what impacts a customer can expect
during drought periods, an analysis of water demands, and the impacts to water supply into the future.
TWSD sent notification to the City of Oroville and the County of Butte, more than 60 days prior to the
UWMP public hearing and advising them that the Plan was being reviewed and changes were being
considered. The District received no comments regarding the planning effort from local agencies or
the public.
2.2.1 Public Water Systems
Water Code Section 10644
(a)(2) The plan, or amendments to the plan, submitted to the department…shall include any
standardized forms, tables, or displays specified by the department.
California Health and Safety Code 116275
(h) “Public Water System” means a system for the provision of water for human consumption through
pipes or other constructed conveyances that has 15 or more service connections or regularly serves at
least 25 individual daily at least 60 days out of the year.
TWSD serves one public water system. This UWMP represents the water use and planning
information for the approximately 3,213 households receiving treated domestic water and 24
irrigation and industrial customers within the TWSD service area.
Standardized tables provided by the department have been incorporated in this report and bear the
numbering scheme created by DWR. For example Table 2-1 below is the first table in UWMP Chapter
2. Public Water System information for Thermalito Water and Sewer District is summarized in Table
2-1, below.
2.2.2 Agencies Serving Multiple Service Areas/Public Water Systems
Thermalito Water and Sewer District serves one service area. This UWMP represents the water use
and planning information for the TWSD service area only.
Page | 5
Submittal Table 2‐1 Retail: Public Water Systems
Sewer District
Total
DWR NOTES:
Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in
Submittal Table 2-3. This table identifies the unit of measure selected in Submittal Table 2-3.
NOTES:
2.3 Regional Planning
The Act requires the District to coordinate the preparation of its UWMP with other appropriate
agencies in the area, including other water suppliers that share a common source, water
management agencies, and relevant public agencies, to the extent practicable. The District
coordinated with and sent a letter to the appropriate agencies and other stakeholders 60 days prior
to adoption stating that the 2025 UWMP was being updated, reviewed and amended. A copy of the
letter is provided in Appendix B.
The District coordinates with local planning and land development agencies by providing information
on the adequacy of its water supply, distribution system, and water rates to meet the area’s current
and future growth needs, including: cooperation with the Butte Local Agency Formation Commission
to assist in the development of Municipal Service Review (MSR) Studies; cooperation with the
respective planning departments of the City of Oroville and the County of Butte in the preparation of
CEQA documents and processing applications for subdivisions and commercial developments;
participation with other municipal water purveyors and fire departments in Butte County and the City
of Oroville to plan for the implementation of new fire safety regulations. In addition, The District is
one-third of a Joint Powers Agreement with the City of Oroville and Lake Oroville Area Public Utilities
District (LOAPUD) being the other two entities (MSR, 2006). Copies of UWMP are available at the
District’s main office at 410 Grand Avenue, Oroville, CA for public review.
2.4 Individual or Regional Planning and Compliance
Urban water suppliers may elect to prepare individual or regional UWMPs (CWC §10620(d)(1)). TWSD
is preparing an individual UWMP.
Page | 6
Submittal Table 2‐2: Plan Identification
Select
One RUWMP (Drop Down List)
Individual UWMP
drop-down.
Regional Urban Water Management Plan (RUWMP)
NOTES:
2.4.1 Regional UWMP
Water Code Section 10620
(d)(1) An urban water supplier may satisfy the requirements of the part by participation in area wide,
regional, watershed, or basin wide urban water management planning where those plans will reduce
preparation costs and contribute to achievement of conservation, efficient water use, and improved
local drought resilience.
This UWMP reports solely on the TWSD service area. It has not been prepared to report on a
combined regional service area. The TWSD is not a member of a Regional UWMP.
2.4.2 Regional Alliance
Water Code Section 10608.20
(a)(1)… Urban retail water suppliers may elect to determine and report progress toward achieving
these targets on an individual or regional basis as provided in subdivision (a) of Section 10608.28
(a) An urban retail water supplier may meets its urban water use target within its retail service area,
or through mutual agreement by any of the following:
(1) Through an urban wholesale water supplier.
(2) Through a regional agency authorized to plan and implement water conservation, including, but
not limited to, an agency established under the Bay Area Water Supply and Conservation Agency Act
(Division 31(commencing with Section 81300)).
(3) Through a regional water management group as defined in Section 10537.
(4) By an integrated regional water management funding area.
(5) By hydrologic region.
Page | 7
(6) Through other appropriate geographic scales for which computation methods have been
developed by the department.
(b) A regional water management group, with the written consent of its member agencies, may
undertake any or all planning, reporting, and implementation functions under this chapter for the
member agencies that consent to those activities. Any data or reports shall provide information both
for the regional water management group and separately for each consulting urban retail water
supplier and urban wholesale water supplier.
Thermalito Water and Sewer District is not a member of a regional alliance for the purpose of
addressing the requirements of the Water Conservation Act of 2009 (SB X7-7).
2.5 Fiscal or Calendar Year and Units of Measure
2.5.1 Fiscal or Calendar Year
Water Code Section 10608.20
(a)(1) Urban retail water suppliers… may determine the targets on a fiscal year or calendar year basis.
Annual volumes of water reported in this UWMP are reported on a calendar year basis.
Submittal Table 2‐3: Supplier Identification
begins (mm/dd)
(Select from the drop down list).
DWR NOTES:
Units of measure (AF, CCF, MG) must remain consistent
throughout the UWMP as reported in Submittal Table 2-3.
NOTES:
Page | 8
2.5.2 Reporting Complete 2020 Data
Water use and planning data reported in this UWMP for the calendar year 2025 cover the full twelve
months of the year, as required by the UWMP Guidelines.
2.5.3 Units of Measure
Volumes of water reported in this UWMP are in units of acre-feet.
2.6 Coordination and Outreach
Water Code Section 10631
(h) An urban water supplier that relies upon a wholesale agency for a source of water shall provide
the wholesale agency with water use projections from that agency for that source of water in five-
year increments to 20 years or as far as data is available. The wholesale agency shall provide
information to the urban water supplier for inclusion in the urban water supplier’s plan that identifies
and quantifies, to the extent practicable, the existing and planned sources of water as required by
subdivision (b), available from the wholesale agency to the urban water supplier over the same five-
year increments, and during various water-year types in accordance with subdivision (f). An urban
water supplier may rely upon water supply information provided by the wholesale agency in fulfilling
the plan informational requirements of subdivisions (b) and (f).
2.6.1 Wholesale and Retail Coordination
There is no source of wholesale water supply available to TWSD, nor does the District have a need for
such supplies.
2.6.2 Coordination Other Agencies and the Community
The Act requires the encouragement of public participation and public hearing as part of the UWMP
approval process. As required by the Act, prior to adopting this UWMP, the District made the UWMP
available for public review and held a public hearing to solicit comments. The hearing provided an
opportunity for District customers, residents and employees in the service area to learn about and
comment on the existing water supply and District plans for providing a reliable, safe, high-quality
water supply for the future.
The District has actively encouraged community participation in its urban water management
planning efforts since the first plan was developed in 1986. In January 1989 a revised plan was
approved by the District Board of Directors and a copy was sent to the State Water Resource Control
Board (SWRCB) in Redding. In 1990 the Department of Water Resources (DWR) reminded water
agencies that updated water management plans needed to be filed with the California Department
of Resource by December 31, 1990. After careful review, the District's legal counsel determined that
the requirements of the Act for preparation and adoption of the UWMP did not apply to the District.
The Act is applicable to agencies supplying more than 3,000 acre feet (AF) of water per year or
providing water to more than 3,000 connections. Since the District did not meet the threshold for an
UWMP, the 1986 Plan was not updated.
Page | 9
In 1995 and 2000 TWSD's Board of Directors reviewed the possible benefits an updated water
management plan would provide the District. In anticipation that the District would exceed the three
thousand customer threshold, it was determined that it would be in the District's best interest to
update the UWMP. At each five year window, at the respective general board meeting, the updated
version was approved.
However, in 2005 the District was in the midst of a management change. Since the District did not
meet the Act’s minimum threshold, it was decided that the District would forgo the required update
at that time.
In 2010, the District serviced 2,893 accounts and a population of 9,654 residents. The 2010 UWMP
update was adopted by the District's Board of Directors in July 2011.
In 2011 the District serviced over 2,917 connections and an estimated population of 9,760 residents.
The 2015 UWMP includes an update of population and service data as well as discussions pertaining
to Water Shortage Contingency Planning (Section 5). A part of the preparation of the UWMP is the
identification of Demand Management Measures (DMMs) and Best Management Practices (BMPs),
refer to Section 6. DMMs are specific actions a water supplier takes to support its water conservation
efforts. BMPs have been identified by the California Urban Water Conservation Council (CUWCC) and
correspond to the 14 DMMs that are to be evaluated in an UWMP. The Act requires that DMMs
provide a schedule for implementation. Please refer to Section 6 for the specific DMMs that will be
implemented as part of this UWMP.
In 2015, the District serviced 2,943 connections and an estimated population of 10,197 residents.
Although the District did not meet the Act’s minimum requirements and was not required to
complete an UWMP, the district prepared an UWMP update. The document was not adopted by the
District’s Board of Directors, however.
The District is now required to prepare an UWMP because the District meets the Act’s minimum
requirements of over 3,000 connections. This 2025 UWMP update integrates planning and
emergency measures and protocols to address climate change and events such as extended droughts
lasting more than 5 years.
2.6.3 Notice to Cities and Counties
Water Code Section 10621(b)
Every urban water supplier required to prepare a plan pursuant to this part shall, at least 60 days
before the public hearing on the plan required by Sections 10642, notify any city or county within
which the supplier provides water supplies that the urban water supplier will be reviewing the plan
and considering amendments or changes to the plan.
On 5/18/2026 the District notified Butte County Water and Resource Conservation, as well as the City
of Oroville, and Butte County Development Services that it was in the process of updating its UWMP
to the 2025 standards.
Page | 10
This UWMP was prepared by the Thermalito Water and Sewer District. If you have any questions
regarding this UWMP, please contact:
Jayme Boucher, General Manager
Thermalito Water And Sewer District
410 Grand Avenue
Oroville, CA 95965
(530) 533-0740
jboucher@TWSD.info
A copy of the final version of this report will be available at the public library, and the California State
Library.
Page | 11
CHAPTER 3 ‐ SYSTEM DESCRIPTION
Water Code Section 10631
(a) Describe the service are on the supplier, including current and projected population, climate, and
other social, economic, and demographic factors affecting the supplier’s water management
planning. The projected population estimates shall be based upon data from the state, regional, or
local service agency population projections within the service area of the urban water supplier and
shall be in five-year increments to 20 years or as far as data is available. The description shall include
the current and projected land uses within the existing or anticipated service area affecting the
supplier’s water management planning. Urban water suppliers shall coordinate with local and
regional land use authorities to determine the most appropriate land use information, including,
where appropriate, land use information obtained from local or regional land use authorities, as
developed pursuant to Article 5 (commencing with Section 65300) of Chapter 3 of Division 1 of Title 7
of the Government code.
This section provides a description of the District service area, climate, population, demographics,
and the physical water supply system including transmission, treatment and distribution facilities.
This section includes the following subsections:
3.1 General Description
3.2 Service Area Boundary Map(s)
3.3 Service Area Climate
3.4 Service Area Population, Demographics, and Socioeconomics
3.5 Land Uses within Service Area
The District currently serves a forecasted population of approximately 12,434 people through more
than 3,213 active water meter connections. The Board of Directors is comprised of five members
elected by the citizens within the service area.
3.1 General Description
The District is located on the east side of the Sacramento Valley at the base of the Sierra Nevada
foothills in southern Butte County, California, northwest of the City of Oroville and southwest of Lake
Oroville. The District is within the Sacramento River Subbasin of the Sacramento River Basin, which is
comprised of the American River Subbasin, Feather River Subbasin, and Sacramento River Subbasin.
The District is also located in the East Butte Groundwater Subbasin of the Sacramento Valley
Groundwater Basin. The East Butte Subbasin is bounded on the west and northwest by Butte Creek,
on the northeast by the Cascade Ranges, on the southeast by the Feather River and the south by the
Sutter Buttes. Figure 1, Location Map.
The northwestern portion of District is located in the Sacramento River watershed and the
southeastern portion of the District, including District’s Concow Reservoir is the Feather River
watershed. Predominant vegetative types within the District’s watersheds include a mixture of blue
oak woodland, montane hardwood forest and chaparral, grassland, and riparian vegetation.
Page | 12
The District was established in April 3, 1922 as Thermalito Irrigation District (TID), and supplied water
to an area of approximately 3,164 acres with a population of approximately 360 properties owners.
The District was formed with the express purpose of providing agricultural water to the Thermalito
community.
The District’s water supply is provided primarily from the Concow Reservoir, with surface water rights
allowing for the diversion of 8,200 AF annually. Under agreement with the State Department of Water
Resources (DWR), the water flows from Concow Reservoir into Lake Oroville. The water is conveyed
through DWR’s State Water Project (SWP) facilities, including Lake Oroville, Oroville Dam, and the
Thermalito Complex, which includes the Thermalito Diversion Pool and Thermalito Power Canal. The
District pumps its supply from the Thermalito Power Canal to its Water Treatment Plant (WTP). Figure
3, TWSD Water Conveyance and Distribution System.
Backup or supplementary groundwater supply is provided by four wells. As currently equipped, these
wells are generally sufficient for low flow winter demand conditions, but not for the maximum
summer flow conditions. The sustainable capacity of these wells is unknown. However, on average
they are operated to supply 373 acre-feet per year (AFY) with a peak flow of 716 AFY.
The District has 3.5 million gallons (MG) of treated storage capacity to provide pressure to the system
and prevent water shortages during periods of high demand. One reservoir is a 2.5 MG distribution
reservoir on the lower flanks of Table Mountain. There is also a 1 MG clearwell located at the WTP.
This storage, in addition to the wells, provides backup that can support the maximum demand in the
District for a short period of time.
The District has approximately 59.1 miles of water distribution pipe which consists of a 24-inch main
that runs from the 2.5 MG storage reservoir to the WTP. Water is delivered to the treatment
plant by a 48-inch main that taps into the Thermalito Power Canal. The WTP relies upon micro-
filtration followed by disinfection for the treatment process.
Surface and groundwater sources tie into the central distribution system extending service
throughout the urban areas of the District. The distribution network contains adequate
surplus capacity to expand service to properties within the District’s existing boundaries planned for
future development.
Treatment System
Water is pumped from the Power Canal to the District's treatment plant, which began operation
in January 1974. The plant is located on a 10.2-acre site, on the north side of the canal,
approximately 1/4 mile east of State Highway 70. Water can be pre-chlorinated, if needed, as it
enters the 4.0 MG microfiltration system, which was installed in 2008. The water is applied to four
filter racks consisting each of 74 modules of membrane filter tubes. When water leaves the filter
racks it is post-chlorinated before entering the MG clearwell approximately 100 feet from the filters.
Page | 13
The District has good quality raw water supplies. Water is delivered to the treatment plant by a 48-
inch main that taps into the State Power Canal. Turbidity in the Power Canal averages 1 NTU
(nephelometric turbidity unit) during the summer. In the winter, turbidity ranges from 15 – 20 NTU.
Typically, high turbidity would require a significant amount of backwash to be run through the
treatment plant; however, backwash flows stay consistent even when influent NTU goes up to 15-20
NTU during the peak of the winter season (December). Therefore, the efficiency and ultimate capacity
of the plant is relatively consistent. The WTP relies upon micro-filtration followed by disinfection for
the treatment process.
Delivery System
Water from the wet well is pumped through a microfiltration system and is disinfected and stored in
the clear well at the treatment plant until the proper contact time with the chlorine is met. From the
clearwell the processed water is pumped into a 24" distribution main that commutes the water
directly to the base of the 2.5 MG storage tank (2.5-MGT), located 0.5-miles north of the treatment
plant. From the 2.5-MGT, the water flows through a new 30" distribution main back to Table
Mountain Boulevard where it begins its path through the distribution system. The 2.5-MGT was
constructed in 1983 (since been replaced), to replace a 5 MG open storage reservoir, located on the
same site (known as the Thermalito Water and Sewer District Forebay). That storage reservoir had
been used since 1924. Gravity flow from the tank produces adequate line pressure throughout the
system.
The 8.0 MG microfiltration system has adequate room for expansion. The current treatment building
has adequate area to install microfiltration racks to process 10 MG of water. An additional storage tank
can also be constructed adjacent to the existing 2.5 MGT tank if warranted.
3.2 Service Area Boundary Map
The District’s service area encompasses the northwestern portion of the City of Oroville, as well as
the portions of the unincorporated areas surrounding the Thermalito Forebay and northeast of Table
Mountain Boulevard. Located outside of the District service boundaries is Concow Reservoir, the
District's main storage reservoir. Concow Reservoir (also known as Wilenor Reservoir) is
approximately 11 miles north of the District’s northernmost service area boundary. The reservoir sits
at an elevation of approximately 2,000 feet. Figure 2, Service Area Map.
3.3 Service Area Climate
Water Code Section 10631(a)
A plan shall… Describe the service area of the supplier, including… climate
Water Code Section 10630
Page | 14
It is the intention of the Legislature, in enacting this part, to permit levels of water management
planning… while accounting for impacts of climate change.
The 14,873-acre service area includes an elevation range from a low point of approximately 174 to
243 feet above sea level.
The District is located in the Sacramento Valley Air Basin (SVAB). The SVAB includes Butte,
Sacramento, Sutter, and Yolo Counties and parts of Solano, Placer, and El Dorado Counties. The SVAB
is bounded on the west by the Coast Ranges and on the north and east by the Cascade Range and
Sierra Nevada. The SVAB has a Mediterranean climate characterized by hot, dry summers and cool,
rainy winters. Summers are warm to extremely warm with temperatures ranging from the upper 60s
to low 110s. Winter months are cool to cold with temperatures from the mid-30s to low-60s, and an
annual average temperature of 67ºF.
The average monthly temperature ranges from a low of 54.9 in January to a high of 96.4 in July. The
average monthly rainfall totals range from a low of 0.04 inches in July to a high of 5.65 inches in
January, refer to Figure 4, District’s Average Monthly Temperature and Average Monthly Rainfall
Totals from 1953 to 2005.
3.4 Service Area Population, Demographics, and Socioeconomics
3.4.1 Service Area Population
Water Code Section 10631
(a)Describe the service area of the supplier, including current and projected population…The projected
population estimates shall be based upon data from the state, regional, or local service agency
population projections within the service area of the urban water supplier and shall be in five-year
increments to 20 years for as far as data is available.
The District serves a population of approximately 12,434 people. Customers include single and
multiple family residences, a variety of commercial and industrial uses, and public facilities including
schools and recreational facilities. Land uses within the District are primarily very low and low density
residential. The few commercial and industrial uses are found primarily along major roads in the
District, such as Oro-Dam Boulevard West (State Route 162/SR 162) and Grand Avenue.
Approximately one-third of the customers in the District are in the City of Oroville, with the remainder
in nearby unincorporated areas of Butte County. The Oroville Airport is within the District’s service
area, but the area between the Thermalito Afterbay and the airport is outside the service area. There
is significant overlap of the District’s Sphere of Influence (SOI) and the City of Oroville’s SOI.1
The District’s service area encompasses the northwestern portion of the City of Oroville, as well as
portions of the unincorporated areas surrounding the Thermalito Forebay northeast of Table
Mountain Boulevard. Located outside of the District service boundaries is Concow Reservoir, the
1 TWSD, Thermalito Water and Sewer District, 2012. Water and Sewer Master Plan Report.
Page 3.
Page | 15
District’s main storage reservoir. Concow Reservoir is approximately 11 miles north of the District’s
northernmost service are Boundary. The reservoir sits at an elevation of approximately 2,000 feet.
Population projections for the District were based on review of the data used in previous District
plans, the City of Oroville General Plan, Butte County General Plan, Butte County Association of
Governments (BCAG), and Local Agency Formation Commission (LAFCo).
The 2006 Butte County LAFCo Municipal Service Review (MSR) for the District identified a 2005
population of 9,140 people and a 2.6% growth rate. This growth rate is consistent with that used for
the City of Oroville’s population projections. BCAG identifies growth rates using a low to high
percentage scale. Using BCAG’s 2010 census growth projection, the low growth rate for the City of
Oroville is 2.5% and the County’s unincorporated area is 1.1%.
To determine a growth rate applicable to the District, the 2010 census data available from BCAG and
census block data within the District’s service area were compared. The resulting population within
the District is estimated at 9,699 in 2010. Although the total county population has been increasing,
the population of the unincorporated portion of Butte County has generally been declining since 1990
due to annexation.1 The growth forecast for unincorporated areas such as Thermalito originally
predicted a .52% growth rate, but the effects of the 2018 Camp Fire triggered a redistribution of Butte
County’s population. The service area has seen an increase in multi-family housing with 5 apartment
complexes completed in the last 5 years. Utilizing a 3.8 persons per connection factor based upon
historical connections along with the predicted growth rate, the forecasted populations are shown in
table 3-1 below.
Submittal Table 3‐1 Retail: Population ‐ Current and Projected
Water Code Section 10631(a)
Population
Served
2025 2030 2035 2040 2045 2050(opt)
12,434 12,682 12,935 13,193 13,457 13,726
3.4.2 Other Social, Economic, and Demographic Factors
Water Code Section 10631
(a) Describe the service area of the supplier, including… Other social, socioeconomic and demographic
factors affecting the supplier’s water management planning.
According to the California Department of Finance, US Census Bureau 2022 data, households in Butte
County, CA have a median annual income of $64,738, which is less than the median annual income
of $83,730 across the entire United States. The economy of Butte County, CA employs 87,900 people.
The largest industries in Butte County, CA are Health Care and Social Assistance (16,421 people),
Retail Trade (12,823 people), and Educational Services (9,625 people), and the highest paying
industries are Utilities ($94,688), Transportation, Warehousing, and Utilities ($59,219), and Mining,
Quarrying, and Oil and Gas Extraction ($51,369).
Page | 16
Population under 18: 20.4%
Population 10-64: 63%
Population over 64: 19.1%
Median Age: 36.8
Workforce: 92,000
Employed: 87,900
Unemployment Rate: 4.5%
Median Household Income: $64,738
Per Capita Income: $33,424
Families at or Below Poverty Level: 16.5%
Median Home Price: $449,000
3.5 Land Uses within Service Area
Water Code Section 10631(a)
The Description shall include the current and projected land uses within the existing or anticipated
service area affecting the supplier’s water management planning. Urban water suppliers shall
coordinate with local or regional land use authorities to determine the most appropriate land use
information, including, where appropriate, land use information obtained from local or regional land
use authorities…
The City of Oroville General Plan Land Use Map designates much of the service area of the District as
Residential. The designated land uses within the unincorporated areas in the District’s Service Area
includes Rural Residential, Very Low and Low Density Residential, and Multi-Family Residential. Areas
within the District’s sphere of influence are primarily designated as Agriculture in the Butte County
General Plan.
The District’s service area lies in portions of Butte County Supervisorial Districts 1 and 4.
~ City Limits
c::::J County Boundary
c::J Sphere of Influence
Service Area
Lakes & Reservoirs
Major River
Tehama County
Glenn
County
Butte Ci Hwy
BiggscP
•
Plumas County
Butte County
Yuba County
Colusa
County
Sutter County 0 4 8
FIGURE 1: PROJECT LOCATION
•
Thermalito Water and Data Source: TWSD, Butte County, Non ,..THST AR Sewer District Bureau of Land Management, Esri , HERE,
1'_ lI\.. Garmin , USGS , NGA , EPA, USDA, NPS
Urban Water Management Plan
111 MISSION RANCH BLVD., SUITE 100 CHICO, CA 95926 1-----~----~-------,1--------------
PHONE: (530) 893-1600 -www.NorthStarEng .com -Job No . Date Created : Created By: Spatial Reference:
21-066 09/08/2021 TDA NAD 1983 State Plane California Zone II
::i::
Oroville Dam ~,
Thermalito
Afterbay
irhermalito
F rebay Thennalito
,---1_
I I
I IJ _..,
Littlefield
Reservoir
Cannon
Reservoir
Thermalito
Diversion
Pool
Lake Oroville
Kelly
Ridge Area
Miners Ranch
Reservoir
Wyandotte
r::J Sphere of Influence N
Service Area (14,873 Acres) •
i_-_-J Oroville City Limits '
Lakes & Reservoirs
Rivers & Streams
--Highway 0 2 3 4
Miles
FIGURE 2: SERVICE AREA AND SPHERE OF INFLUENCE
Thermalito Water and Data Source: 1WSD, Butte County,
• Non ,..THST AR Sewer District Bureau of Land Management, Esri, HERE, 1'._ l..l'\. Garmin, USGS, NGA, EPA, USDA, NPS
Urban Water Management Plan
111 MI SSI ON RANC H BLVD., SU ITE 100 CHI CO, CA 95926 -----~----~------------------
PHONE : (530) 893-1600 -www.North StarEn g.com -Job No . Date Created : Created By : Spatial Reference:
21-066 09/08/2021 TDA NAD 1983 State Plane California Zone II
0
i .,.
0
•
I
Co l lom•-'lo cl Rd
Water Tank
Well
Water Mains
Forebay
Mo un u ,n
-, Go ff
• Co u rse
..
N
C l y F'1 l
S\IRA
Nelson
0
l
"' u
&
L
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Treatment
Plant with
1.0 M Gallon
Thermalito
Diversion
Pool
0 n F a Thermalito
Power Canal
I
~ro, ... mir:
lito
anal
P,11,.rm o
Diversion
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,497R
0 2
FIGURE 3: WATER CONVEYANCE AND DISTRIBUTION SYSTEM
3 4
Miles
•
Thermalito Water and Data Source: TWSD, Butte County, Non ,..THST AR Sewer District Bureau of Land Management, Esri , HERE,
1'_ lI\.. Garmin , USGS , NGA , EPA, USDA, NPS
Urban Water Management Plan
111 MISSION RANCH BLVD., SUITE 100 CHICO, CA 95926 1------------------+----------------
PHONE: (530) 893-1600 -www.NorthStarEng .com -Job No . Date Created : Created By: Spatial Reference:
21-066 09/08/2021 TDA NAD 1983 State Plane California Zone II
120 -.------------------------------------,-6
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.!:
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Ill {=
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{E :E
> c
:E 0 .... :E C: QI 0
:E bl)
60 3~ QI QI
bl) ~ "' ~
~
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Average Monthly High Temperature{°F) 55 .1 60.8 65.3 71.7 80.8 89.8 96.4 94 .7 89 78 .6 64.7 55.3
-Average Monthly Rainfall (Inches) 5.55 4.84 4.05 2 .21 1 0.44 0.04 0.14 0.4 1.65 3.57 4.8
FIGURE 4: Average Monthly Temperatures and Rainfall
Thermalito Water and Data Source: WESTERN REGIONAL
• Non ,..THST AR Sewer District CLIMATE CENTER -OROVILLE, 1'_ lI\.. CALIFORNIA (046521)
Urban Water Management Plan
111 MISSION RANCH BLVD., SUITE 100 CHICO, CA 95926 1-----------------+--------------
PHONE: (530) 893-1600 -www.NorthStarEng .com -Job No. Date Created : Created By: Period of Record:
21-066 11/22/2 021 TOA 03/01 /1893 to 05/3 1/2 016
Disadvantaged Communities
1111 Severely Disadvantaged Community (MHI < $42,737)
Disadvantaged Community ($42,737 ~ MHI < $56,982)
Lakes & Reservoirs
c::::J County Boundary
1c t l e
Lake
Oroville
Kelly Ridge
Berry Creek
Oroville East
Palermo
N
0 2 4 6 8
•:::1111□••-===••• Miles
FIGURE 5: Disadvantaged Communities, Thermalito
NORTHSTAR Sewer District
Data Source: TWSD, Butte County,
Bureau of Land Management, Esri , HERE,
Garmin , USGS , NGA , EPA, USDA, NPS •
Thermalito Water and
Urban Water Management Plan
111 MISSION RANCH BLVD., SUITE 100 CHICO, CA 95926 t-----~--------.-----1---------------1
PHONE: (530) 893-1600 -www.NorthStarEng .com -Job No . Date Created : Created By: Spatial Reference:
21-066 11/22/2021 TOA NAO 1983 State Plane California Zone II
Page | 17
CHAPTER 4 – WATER USE CHARACTERIZATION
This chapter provides descriptions and quantifications of TWSD’s past, current, and future water use
projected uses through the year 2050. This characterization provides a realistic projection of future
water supply and demand needs.
This chapter is divided into the following subsections:
4.1 Non-Potable vs. Potable Water Use
4.2 Past, Current, and Projected Water Uses by Sector
4.2.1 Water Use Sectors Listed in Water Code
4.2.2 Past Water Use
4.2.3 Current Water Use
4.2.4 Projected Water Use
4.2.5 Distribution System Water Losses
4.3 Water Use for Lower Income Households
4.4 Climate Change Considerations
4.1 Non-Potable vs. Potable Water Use
Thermalito Water and Sewer District does not currently make use of recycled water because there is
no wastewater recycled for direct use within the service area. For the District the focus of this chapter
is the historical and projected potable water uses.
4.2 Past, Current, and Projected Water Use by Sector
Water Code Section 10635
(a) Every urban water supplier shall include, as part of its urban water management plan, an
assessment of the reliability if its water service to its customers during normal, dry, and multiple dry
water years. This water supply and demand assessment shall compare the total water supply sources
available to the water supplier with the long-term total projected water use over the next 20 years, in
five-year increments, for a normal water year, a single dry water year, and a drought lasting five
consecutive water years. The water service reliability assessment shall be based upon the information
compiled pursuant to Section 10631, including available data from state, regional, or local agency
population projections within the service area of the urban water supplier.
Water Code Section 10631 (d)
(1) For an urban retail water supplier quantify, to the extent records are available, past and current
water use, over the same five-year increments described in subdivision (a), and projected water use,
based upon information developed pursuant to subdivision (a), identifying the uses among water use
sectors, including, but not necessarily limited to , all of the following…
(2) The water use projections shall be in the same five-year increments described in subdivision (a).
4.2.1 Water Use Sectors Listed in Water Code
Water Code Section 10631 (d)
(1) For an urban retail water supplier, quantify, to the extent records are available, past and current
water use, over the same five-year increments described in subdivision (a), and projected water use,
Page | 18
based upon information developed pursuant to subdivision (a), identifying the uses among water use
sectors, including, but not necessarily limited to, all of the following:
(A) Single-family residential
(B) Multifamily
(C) Commercial
(D) Industrial
(E) Institutional and governmental
(F) Landscape
(G) Sales to other agencies
(H) Saline water intrusion barriers, groundwater recharge, or conjunctive use, or any combination
thereof
(I) Agricultural
(J) Distribution system water loss
Using available historical records, water demands are provided by customer type and projected over
the next 25 years as shown table 4-2. Records for actual historical water use were provided from the
District’s DWR Public Water System Statistics. Projected demands are based on the estimated
population and growth rate.
As seen in Table 4-1 below, water use is presented in the following use categories: single family
residential, multi-family residential, commercial, industrial, institutional/governmental, agricultural
irrigation, and distribution losses.
4.2.2 Past Water Use
Population estimates that drive the projections of water use were derived from the California
Department of Finance. The Butte County Association of Governments used their data to provide
projections for growth in Butte County into the future. These population estimates together with the
water use targets provide the basis for projected water use.
4.2.3 Current Water Use
The District does not regularly sell water to other agencies, nor does it provide water for saline
barriers, groundwater recharge, conjunctive use, or recycling. Water use is broken out by demand
sector to the extent possible using available records. The District has been working at improving data
reporting for each use category.
Page | 19
Submittal Table 4‐1 Retail: Total Uses for Potable and Non‐Potable Water — Actual
Water Code Section 10631(d)(1)
Use Type Additional Description
(as needed)
2025 Actual Water Use
May select each use multiple times
These are the only use types that will be recognized by the WUEdata online submittal tool
Potable or Non‐Potable
(OPTIONAL)
Drop down list
Total
DWR NOTES: Units of measure (AF, CCF, MG)
2-3. This table identifies the unit of measure selected in Submittal Table 2-3.
NOTES:
4.2.4 Projected Water Use
Water Code Section 10635 (a)
Every urban water supplier shall include, as part of its urban water management plan, an assessment
of the reliability of its water service to its customers during normal, dry, and multiple dry water years.
This water supply and demand assessment shall compare the total water supply sources available to
the water supplier with the long term projected water use over the next 20 years, in five-year
increments, for a normal water year, a single dry water year, and a drought lasting five consecutive
water years. The water service reliability assessment shall be based upon the information compiled
pursuant to Section 10631, including available data from state, regional, or local agency population
projections within the service area of the urban water supplier.
Water Code Section 10631
(h) An urban water supplier that relies upon a wholesale agency for a source of water shall provide
the wholesale agency with water use projections from that agency for that source of water in five-
year increments to 20 years or ads far as data is available…The wholesale agency shall provide
information to the urban water supplier for inclusion in the urban water supplier’s plan that identifies
and quantifies, to the extent practicable, the existing and planned sources of water as required by
Page | 20
subdivision (b), available from the wholesale agency to the urban water supplier over the same Five-
year increments, and during various water-year types in accordance with subdivision (f). An urban
water supplier may rely upon water supply information provided by the wholesale agency in fulfilling
the plan informational requirements of subdivisions (b) and (f).
Water Code Section 10631 (d) (4)
(4)(A) Water use projections, where available, shall display and account for the water savings
estimated to result from adopted codes, standards, ordinances, or transportation and land use plans
identified by the urban water supplier, as applicable to the service area.
(B) To the extent that an urban water supplier reports the information described in subparagraph (A),
an urban water supplier shall do both the following: (i) provide citations of the various codes,
standards, ordinances, or transportation and land use plans utilized in making the projections. (ii)
Indicate the extent that the water use projections consider savings from codes, standards, ordinances,
or transportation and land use plans. Water use projections that do not account for these water
savings shall be noted of that fact.
Projected Water Use through 2045 is summarized in Table 4-2. Future demands (year 2025 and
following) were projected as the product of the estimated population for the target year and the
2020 consumption records. Future sector demands were projected proportionally to actual sector
demands experienced from 2015 to 2020.
Page | 21
Submittal Table 4‐3 Retail: Inclusion in Water Use Projections
Water Code Section 10631 (a), 10631 (d)(4)(A), and 10631 (d)(4)(B)
Drop down list (y/n)
state the section or page number
Optional Suppliers may complete Optional Submittal Table 4-
Are Lower Income Residential Demands Included In Projections?
Drop down list (y/n)
No
Optional If the method for accounting Lower Income Residential Demands has been included,
provide page number where this accounting can be found.
DWR NOTES:
Submittal Table 4‐2 Retail: Total Uses for Potable, and Non‐Potable Water —
Projected
Additional
Description
(as needed)
(Report To the Extent that Records are Available)
Drop down list
May select each use multiple times
These are the only Use Types that will be recognized by the
WUEdata online submittal tool
Potable or Non‐
Potable
(OPTIONAL)
Drop down list
2030
(AF) (AF) (AF) (AF) (AF)
Add additional rows as needed.
Single Family Potable 1,413 1,521 1,637 1,761 1,895
Multi-Family Potable 331 346 362 379 396
Commercial Potable 63 67 73 79 85
Institutional/Governmental Potable 343 370 399 430 464
Industrial Potable 25 26 27 28 29
Landscape Potable 48 53 59 66 73
Subtotal Potable 2,223 2,383 2,557 2,743 2,942
Subtotal Non-Potable 0 0 0 0 0
2,223 2,383 2,557 2,743 2,942
) must remain consistent throughout the UWMP as reported in Submittal Table
2-3. This table identifies the unit of measure selected in Submittal Table 2-3.
NOTES:
Page | 22
4.2.5 Distribution System Water Loss
Water Code Section 10631(d) (1)
For an Urban Retail water supplier, quantify to the extent records are available, past and current
water use, over the same five-year increments described in subdivision (a), and projected water use,
based on information developed pursuant to subdivision (a), identifying the uses among water use
sectors, including, but not necessarily limited to, all of the following…
(J) Distribution system water loss…
Water Code Section 10631(d)(3)
(A) The distribution system water loss shall be quantified for each of the five years preceding the plan
update, in accordance with rules adopted pursuant to Section 10608.34.
(B) The Distribution system water loss quantified shall be reported in accordance with a worksheet
approved or developed by the department through a public process. The water loss quantification
worksheet shall be based on the water system balance methodology developed by the American
Water Works Association.
(C) In the plan due by July 1, 2021, and in each update thereafter, data shall be included to show
whether the urban retail water supplier met the distribution loss standards enacted by the board
pursuant to Section 10608.34.
Page | 23
System losses are a result of distribution and treatment system maintenance and is non-metered
water. Table 4-4 below, depicts a five year audit of system real and apparent water losses. Water loss
within the District has been reduced since 2000 due to system improvements and replacement
projects.
Submittal Table 4‐5 Retail: Water Loss Audit Reporting
Water Code Section 10631(d)(3)(A)
Reported in Table 2‐1 R
Reporting Period Submitted to DWR Water
Loss Audit Program
(yes/no)
Report submittal status for all five years for each Public Water System as available.
Add rows as needed
Yes
Yes
Yes
Yes
Yes
Suppliers will provide a link to the WUEdata submittals of their Water
Loss Audit Reports.
NOTES:
4.3 Water Use for Lower Income Households
Water Code Section 10631.1
(a) The water use projections required by section 10631 shall include projected water use for single-
family and multifamily residential housing needed for lower income households, as defined in Section
50079.5 of the Health and safety code, as identified in the housing element of any city, county, or city
and county service area of the supplier.
California Health and Safety Code Section 50079.5 (a)
“Lower income households” means persons and families whose income does not exceed the qualifying
limits for lower income families… In the event the federal standards are discontinued, the department
shall, by regulation, establish income limits for lower income households for all geographic areas of
the state at 80 percent of area median income, adjusted for family size and revised annually.
Page | 24
California State Bill No. 1087 (SB 1078), Chapter 727, became effective January 1, 2006 and amended
Government Code Section 65589.7 and Water Code Section 10631.1 SB 1087 requires local
governments to provide a copy of their adopted housing element to water and sewer providers. In
addition, it requires water providers to grant priority for service allocations to proposed
developments that include housing units for lower income families and workers. Subsequent
revisions to the Urban Water Management Planning Act require water providers to develop water
demand project for lower income single and multi-family households.
The District does not maintain records of the income level of its customers and does not discriminate
in terms of supplying water to any development. Connections in the District are provided first come,
first serve based upon available capacity. The District serves any development that occurs within its
service area, regardless of the targeted income level of the future residents. It is ultimately the City’s
or County’s responsibility to approve or not approve developments within the service area.
4.4 Climate Change Considerations
Water Code Section 10630
It is the intention of the Legislature, in enacting this part, to permit levels of water management
planning commensurate with the numbers of customers served and the volume of water supplied,
while accounting for impacts from climate change.
Water Code Section 10635(b)
Every Urban water supplier shall include, as part of its urban water management plan, a drought risk
assessment for its water service to its customers as part of information considered in developing the
demand management measures and water supply projects and programs to be included in the urban
water management plan. The urban water supplier may conduct an interim update or updates to this
drought risk assessment within the five-year cycle of its urban water management plan update. The
drought risk assessment shall include each of the following…
(4) Considerations of the historical drought hydrology, plausible changes on projected supplies and
demands under climate change conditions, anticipated regulatory changes, and other locally
applicable criteria.
Page | 25
TWSD is not a large enough water District to embark on the creation of planning documents beyond
the scope of its service area. The district does, however, participate in countywide planning efforts,
and utilizes those documents for general guidance. The Butte County Climate Action Plan (CAP) is an
implementation mechanism of the county’s General Plan, and provides goal, policies, and programs
to reduce greenhouse gas (GHG) emissions, address climate change adaptation, and improve quality
of life in the county. Programs and actions defined in the CAP will help the county sustain its natural
resources, grow efficiently, ensure long-term resiliency to a changing environmental and economic
climate, and improve transportation. Climate change is expected to influence existing hazards and
vulnerabilities. While anticipating consequences of a changing climate is a challenging task, the work
plan prioritizes actions for the County to adopt to protect resources and prepare for changing
precipitation patterns, reduced water supply, and increased hazards such as flooding, heat waves,
and wildfire. Measures in the CAP and proactive steps will help the County achieve the General Plan
vision of thriving communities, a strong agricultural base, and healthy natural resources.
Changes is precipitation patterns may affect snowpack in the mountains to the east of the county as
well as reduce groundwater recharge. Both of these effects can reduce access to drinking water and
agricultural irrigation. Through education, efficiency, and conservation, the following District
supported adaptations actions will help our customers, and all Butte County residents, prepare for a
future where water may be less plentiful and more expensive.
- Collaborate with Northern Sacramento Valley Integrated regional Water Management
agencies to include climate change considerations in the Integrated Regional Water Resource
Management Plan (IRWRMP). Monitor climate change effects on water resources and update
future IRWIMPs accordingly.
- Support other agencies to help vulnerable populations conserve water and reduce household
resource costs through income-qualified subsidies and rebates for water efficient equipment
upgrades.
- Collaborate with water providers to incorporate anticipated water supply changes that may
result from reduced snowpack and lower groundwater levels into agricultural management
plans.
California is currently in the process of adopting a 2021 State Climate Adaptation Strategy that further
defines goals and metrics for building resilience and reducing climate induced risks across the state.
Page | 26
CHAPTER 5 – SBX7‐7 BASELINES, TARGETS, AND 2025 REPORTING
The goal of the SBX7-7 Baseline, Targets, and 2020 Compliance chapter in the supplier’s 2020 UWMP
was to allow the retail Supplier to demonstrate its compliance with its 2020 targeted water-use
reduction, as required in the Water Conservation Act of 2009. The calculation of baselines, targets,
and 2020 compliance is a very important but highly technical portion of the UWMP.
This chapter includes the following sections:
5.1 Baseline and Target Calculations for 2020 UWMPs
5.2 Methods for Calculating Population and Gross Water Use
5.2.1 Department of Finance
5.2.2 Gross Water Use
5.3 2020 Compliance Daily Per-Capita Water Use (GPCD)
5.3.1 2020 Adjustments for Factors Outside of Supplier’s Control
5.3.2 If Supplier Does Not Meet 2020 Target
5.1 Baseline and Target Calculations for 2025 UWMPs
TWSD did not complete additional SBX7-7 tables as it met its 2020 Target as summarized below and
outlined in the 2020 UWMP
Submittal Table 5‐1 Retail: SB X7‐7 2020 Target Progress
Water Code Section 10608.40
reporting cycle. Proceed to the next table.
Was Supplier part
of a merger or
consolidation
since 2020?
Alliance
Target or
Individual
Target?
GPCD Achieve
Targeted
Reduction for
2020?
Only for suppliers that did not
meet the Target in 2020
See DWR NOTES below.
Actual 2025
GPCD
(From SB X7-7
Compliance
Form)
meet the 2020
Target in 2025?
Target
DWR NOTES:
Suppliers calculating a 2025 GPCD will need to complete and submit SB X 7-7 Compliance Tables to verify the use of SB X7-7
Methodologies.
Suppliers that were part of a merger or consolidation since 2020 see Chapter 5 and Appendix P for guidance.
Page | 27
5.2 Methods for Calculating Population and Gross Water Use
5.2.1 Department of Finance
Water Code Section 10608.20 (e)
An urban retail water supplier shall include in its urban water management plan due in 2010… the
baseline per capita water use…along with the bases for determining those estimates, including
references to supporting data.
(f) When calculating per capita values for the purpose of this chapter, an urban retail water supplier
shall determine population using federal, state, and local population reports and projections.
Water Code Section10644
(a)(2) The plan…shall include any standardized forms, tables or displays specified by the department.
Service population for this UWMP was calculated based upon Department of Finance Data.
Information on how the population figures were developed is included in Section 3 above. Population
data is included in table 3-1, above. Service area population for the baseline periods is summarized
in SB X7-7 Table 3.
5.2.2 Gross Water Use
Water Code Section 10608.12
(h) “Gross Water Use” means total volume of water, whether treated or untreated, entering the
distribution system of an urban retail water supplier, excluding all of the following:
(1) Recycled water that is delivered within the service area of an urban retail water supplier or its
urban wholesale water supplier.
(2) The net volume of water that the urban retail water supplier places into long term storage
(3) The volume of water the urban retail water supplier conveys for use by another urban water
supplier
(4) The volume of water delivered for agricultural use, except as otherwise provided in subdivision (f)
of Section 10608.24
California Code of Regulations Title 23 Division 2 Chapter 5.1 Article 1 Section 596
(a) An urban water supplier that has a substantial percentage of industrial water use in its service
area is eligible to exclude the process water use of existing industrial water customers from the
calculation of its gross water use to avoid a disproportionate burden on another customer sector.
All Gross Water Use within the District is treated and distributed to all customer types. Gross water
use does not incorporate any recycled water use. See Submittal tables 4-1 and 4-2, above.
5.3 2020 Compliance Daily Per-Capita Water Use (GPCD)
Water Code Section 10608.12
(f)”Compliance daily per-capita water use” means the gross water use during the final year of the
reporting period…
Water Code Section 10608.20
Page | 28
(e) An urban retail water supplier shall include in its urban water management plan due in 2010…
compliance daily per capita water use, along with the bases for determining those estimates, including
references to supporting data.
5.3.4 2020 Adjustments for Factors Outside of Supplier’s Control
Water Code Section 10608.24
(d)(1) When determining compliance daily per-capita water use, an urban retail water supplier may
consider the following factors:
(A) Differences in evapotranspiration and rainfall in the baseline period compared to the compliance
reporting period
(B) Substantial changes to commercial or industrial water use resulting from increased business
output and economic development that have occurred during the reporting period
(C) Substantial changes to institutional water use resulting from fire suppression services or other
extraordinary events, or from new or expanded operations, that have occurred during the reporting
period
(2) If the urban retail water supplier elects to adjust its estimate of compliance daily per capita water
use due to one or more of the factors described in paragraph (1), it shall provide the basis for, and
data supporting, the adjustment in the report required by Section 10608.40
5.3.5 If Supplier Does Not Meet 2020 Target
Water Code Section 10608.56
(a) On and after July1, 2016, an urban retail water supplier is not eligible for a water grant or loan
awarded or administered by the state unless the supplier complies with this part.
Page | 29
CHAPTER 6 – WATER SUPPLY CHARACTERIZATION
A thorough Characterization and analysis of water supplies can provide a realistic reliability
assessment of an urban water supplier’s water assets under various hydrological and regulatory
conditions. A thorough analysis examines surface water rights, water entitlements (i.e., contracts for
water delivery), groundwater supplies, raw water supplies, and recycled water supplies. Moreover, it
considers each water asset in the context of the infrastructure systems that convey water to the
supplier’s service area- including infrastructure systems that are shared with other water suppliers.
A detailed water supply analysis examines each water asset and then aggregates the information into
a comprehensive picture of the supplier’s water supply portfolio.
This chapter includes the following sections:
6.1 Water Supply Analysis Overview
6.2 Supplier’s UWMP Water Supply Characterization
6.2.1 Purchased or Imported Water
6.2.2 Groundwater
6.2.3 Surface Water
6.2.4 Storm Water
6.2.5 Recycled Water and Waste Water
6.2.6 Desalinated Water
6.2.7 Water Exchanges and Transfers
6.2.8 Future Water Projects
6.2.9 Summary of Existing and Planned Sources of Water
6.3 Energy Use
6.1 Water Supply Analysis Overview
Water Code Section 10631(b)
Identify and quantify, to the extent practicable, the existing and planned sources of water available
to the supplier [in five-year increments to 20 years or as far as data is available] providing supporting
and related information, including all of the following:
(1) A detailed discussion of anticipated supply availability under a normal water year, single dry year,
and droughts lasting at least five years, as well as more frequent and severe periods of drought, as
described in the drought risk assessment. For each source of water supply, consider any information
pertinent to the reliability analysis conducted pursuant to Section 10635, including changes in supply
due to climate change.
(2) When multiple sources of water supply are identified, a description of the management of each
supply in correlation with the other identified supplies.
(3) For any planned sources of water supply, a description of the measures that are being undertaken
to acquire and develop those water supplies.
The water supply for District customers is a combination of two sources:
• Surface Water
• Groundwater Wells
Page | 30
Surface Water is available from the Concow Reservoir. Groundwater used by the District is extracted
from the Wyandotte Creek Subbasin of the Sacramento River Groundwater Basin. Groundwater
extraction is accomplished using four active wells located throughout the District’s service area. The
maximum output of the wells is roughly 3,258.5 AFY. However, the average acre-feet per year is
estimated at 300 AFY or 14.5% of the total water supplied to consumers. The distribution of each
year’s supply is dependent on several factors. The exact amount of water projected to be used from
each source is difficult to predict. However, for both surface water and groundwater, there is a
surplus available throughout the planning horizon of this UWMP. To simplify this analysis, the District
has assumed that the available supply is equal to the projected demand in any given year.
6.2 Supplier’s UWMP Water Supply Characterization
6.2.1 Purchased or Imported Water
TWSD does not purchase or import any supply, but rather relies on permitted rights to surface water
originating from the combined Concow Reservoir and Feather River Watershed.
6.2.2 Groundwater
Ground water in Butte County is governed by the County’s Groundwater Management Plan.2 The
TWSD service area is included in Butte County Groundwater Management Plan as a portion of the
Wyandotte Creek Subbasin of the Sacramento Valley groundwater basin. See Wyandotte Creek GSA
website for description of the subbasin. The monitoring wells within the basin have experienced a
declining trend for groundwater levels from 1998 to 2018.3 The District is not dependent on
groundwater and can meet water use projections to 2045 with Surface Water supplies.
There are currently four groundwater wells in service within the District’s service area (refer to Figure
3 for the TWSD Water Conveyance and Distribution System in Chapter 3). The primary purpose of
these wells is threefold:
1. Back-up water supply when the primary supply of surface water through the Water
Treatment Plant is shut down or reduced in capacity. This could occur during routine
maintenance, system construction activities, or emergency supply disruption.
2. Additional water to augment the District’s surface water supply during peak demand periods.
3. Water blending to reduce the total effects of the disinfectant byproducts derived from the
Water Treatment Plant microfiltration process.
All of the existing wells are equipped with annular seals. Wells #3, #4 and #5 are on the north end of
the District’s service area, producing high quality water which does not require treatment. Well #2 is
located adjacent to residential developments. Each well is equipped with a sand extraction system.
Preventative chlorination treatment is provided at each well to prevent contamination. The
maximum flow capacity for each of these four wells ranges from 350 gpm to 770 gpm. This results in
a combined peak capacity potential of 2,020 gpm. The “sustainable” capacity of these wells is
unknown.
2 http://www.buttecounty.net/waterresourceconservation/groundwatermanagementplan
3 California’s Groundwater Update 2020 https://water.ca.gov/programs/groundwater-
management/bulletin-118
Page | 33
Submittal Table 6‐1 Retail: Groundwater Volume Pumped
Water Code Section 10631(4) and 10631(4)(c)
Check the box if the Supplier does not pump groundwater.
Proceed to the next table.
Check the box if all or part of the groundwater described below is desalinated. (OPTIONAL)
Groundwater Type
Drop Down List
May use each category
multiple times
or Non-
Potable
(OPTIONAL)
Drop down
Location or Basin Name 2021 (AF) 2022 (AF) 2023 (AF) 2024 (AF) 2025 (AF)
Add additional rows as needed
Alluvial Basin Potable Sacramento Valley Basin 645 501 351 72 49
Total 645 501 351 72 49
DWR NOTES:
Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3. This table
identifies the unit of measure selected in Submittal Table 2-3.
6.2.3 Surface Water
Concow Creek is a minor stream within the Feather River Watershed and drains into Lake Oroville.
The District's primary water supply system is reliant upon water captured and stored from the
Concow Creek watershed in the Concow Reservoir. In August 1923, the District purchased land from
the Pacific Gas & Electric Company (PG&E) for the purpose of development of a reservoir.
Construction of the Concow Dam began in November of 1923 and was completed in December 1924.
The acreage of Concow Reservoir watershed is estimated by DWR as 9,587 acres. Flow in the
catchment area is seasonal and responds to and follows the pattern of precipitation. Elevations range
from 2,000 feet at the base of Concow Dam to 3,600 feet at the uppermost elevation in the
watershed.
In the early years, Concow Reservoir water was used almost solely for irrigation; almost all residences
used the District water for domestic purposes. There were a few private wells in the District, as the
majority of residences could not afford to install wells as the hardpan layers in the Thermalito area
made it cost prohibitive to drill.
Construction of the Oroville Dam and appurtenant facilities of the State Water Project in the 1960's
provided an alternative means of conveying the District's Concow water to the service area. In 1965
the District entered into an agreement with DWR to release its share of Concow water into the West
Page | 33
Branch of the Feather River, either by way of Concow Creek or through the PG&E Lime Saddle power
plant. In 1966 Oroville Dam and Thermalito Diversion Dam were added to the water rights license as
points of power diversion and re-diversion to the District. In 1971, the District’s agreement with DWR
was amended in 1971 to allow delivery of Concow water via Concow Creek to Lake Oroville. DWR
gives credit for water delivered and provides an equivalent amount of Lake Oroville water to the
District delivered through the Thermalito Power Canal. The District has a water right of 8,200 acre
feet from the Concow watershed and at no time shall the reservoir capacity drop below 1,000 acre-
feet to accommodate the fish population. When full, the Concow Reservoir has a capacity of 7,225
acre feet.
The District's water system has changed throughout the years with alterations in conveyance routes
and systems, joint agreements with other agencies including PG&E, California Water Service and
DWR, variations in the primary sources of water used, and acquisition of treatment facilities for
domestic consumption of surface water.
The District has developed a conjunctive water system utilizing both surface and groundwater
supplies. Surface water supplies from the Concow Reservoir comprise the primary source.
6.2.4 Stormwater
Stormwater is not projected for beneficial reuse within the service area of the District.
6.2.5 Wastewater and Recycled Water
The City of Oroville operates and maintains a sewage collection system in portions of the District’s
service area. The sewage collection systems of the City of Oroville terminate at Sewage
Commission – Oroville Region’s (SC-OR) treatment facility. SC-OR’s treated effluent is discharged
to the Feather River south of the City of Oroville. SC-OR does not operate a recycled water
program. Thus, recycled water is not available to the District for use as a water source.
Page | 33
Submittal Table 6‐2 Retail: Wastewater Collected Within Service Area
Water Code Section 10633(a)
Check the box if there is no wastewater collection system.
Proceed to the next table.
Percentage of 2025 service area served by wastewater collection system (OPTIONAL)
Percentage of 2025 service area population served by wastewater collection system
(OPTIONAL)
Wastewater Collection Recipient of Collected Wastewater
Name of Wastewater
Collection Agency
Wastewater
Volume
Metered or
Estimated?
OPTIONAL
Drop Down List
Volume of
Wastewater
Collected from
UWMP Service Area
2025 (AF)
Name of Wastewater
Treatment Plant (WWTP)
and Place ID Number
Drop down list
Is WWTP
Located
Within UWMP
Area?
Drop Down List
Add additional rows as needed
TWSD Metered 502
Sewerage Commission
Oroville Region WWTP,
Place ID 246251
No
Total Wastewater Received from UWMP
Service Area in 2025: 502
DWR NOTES: Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in
Submittal Table 2-3. This table identifies the unit of measure selected in Submittal Table 2-3.
Additional Guidance: See Appendix M, Section M.21 for detailed guidance on this table.
No recycled water supply is expected to be available for the District’s service area within the next 20
years. This is primarily because potential customers are approximately three miles from the
treatment plant, and the costs of transmission and distribution of the recycled water could not be
justified. There is potential for recycling water for irrigation along the freeway corridor and in process
water for industrial uses or a power plant near the SC-OR treatment plant. Interest has been
expressed, but no progress forward has taken place thus far. Therefore, the current projected
recycled water supply for the District’s service area through 2045 is 0 AFY. The District has not
implemented any incentive programs to encourage recycled water use because they do not own and
operate the wastewater system. The implementation of a recycled water program would involve
longer-term measures and require regional participation by other agencies.
Page | 34
Submittal Table 6‐3 Retail: Wastewater Treatment and Outcomes Within UWMP Service Area
Water Code Section 10633(b)
Check the box if no wastewater is treated or disposed of within the UWMP service area.
Proceed to the next table.
Submittal Table 6‐4 Retail: Recycled Water Direct Beneficial Uses Within Service Area
Water Code Section 10633 (c),(d),(e)
Check box if recycled water is not used and is not planned for use within the service area of
the supplier. The supplier will only complete the column on "Potential Recycled Water Use"
and submit an accompanying narrative on the feasibility of that potential recycled water
Submittal Table 6‐5 Retail: 2020 UWMP Recycled Water Use Projection
Compared to 2025 Actual
Water Code Section 10633(e)
Check the box if recycled water was not used in 2025 nor previously
projected for use in 2020.
Proceed to the next table.
6.2.6 Desalinated Water
There are no opportunities for the development of desalinated water in the District. The District is
located in the inland Central Valley, which is more than 120 miles from potential sources of saline
water.
6.2.7 Water Exchanges and Transfers
The District has surplus water in most years. Thus, there is a potential to transfer a portion of
this water to other water agencies. In 2012, the District transferred 1,753 AF of water to the
Westlands Irrigation District. The District will continue to explore these possibilities as a means to
offset supply deficiencies in other service areas and as a means of generating revenues to
provide system improvements to the District.
6.2.8 Future Water Projects
The District currently does not have future project planned with the objective of increasing
water supply.
In 2019, the District removed its existing 1.0 MG welded steel clearwell tank and replaced it with a
1.0 MG glass-steel fused tank. In 2020, the 2.5 MG welded steel distribution tank was also
replaced with a 2.5 MG glass-steel fused tank. Neither of the projects increased the storage capacity,
but it significantly improved contact time and turn-over rates for both tanks. This was primarily due
to reconfigured inlet and outlet pipes.
Page | 35
Submittal Table 6‐7 Retail: Expected Future Water Supply Projects or Programs
Water Code Section 10631(f)
Check the box if there are no expected future water supply projects or programs that provide a
quantifiable increase to the agency's water supply.
Proceed to the next table.
6.2.9 Summary of Existing and Planned Sources of Water
Water Code 10631
Identify and quantify, to the extent practicable, the existing and planned sources of water available
to the supplier over the same five-year increments described in subdivision (a), providing supporting
and related information, including all of the following…
Page | 36
(b)(2) When multiple sources of water supply are identified, a description of the management of each
supply in correlation with other identified supplies.
(h) An urban water supplier that relies upon a wholesale agency for source of water shall provide the
wholesale agency with water use projections from that agency for the source of water in five-year
increments to 20 years or as far as data is available. The wholesale agency shall provide information
to the urban water supplier for inclusion in the urban water supplier’s plan that identifies, to the extent
practicable, the existing and planned sources of water as required by subdivision (b), available from
the wholesale agency to the urban water supplier over the same five-year increments, and during
various water-year types in accordance of subdivision (f). An urban water supplier may rely upon
water supply information provided by the wholesale agency in fulfilling the plan informational
requirements of subdivisions (b) and (f).
Submittal Table 6‐8 Retail: Water Supplies — Actual
Water Code Section 10631(b)
Water Supply
Additional Description
(as needed)
2025
Drop down list
May use each category multiple
times. These are the only water
supply categories that will be
recognized by the WUEdata
online submittal tool
Potable or Non‐
Potable
(after treatment if
treated)
(OPTIONAL)
Drop Down list
Actual
Volume (AF)
Total Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Potable 49
Potable 8,200 8,200
Subtotal Potable
Subtotal Non-Potable
Total
DWR NOTES:
Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3. This table
identifies the unit of measure selected in Submittal Table 2-3.
Total Entitlement: e.g. Water Right, Groundwater Allocation, Contracted Amount.
Submittal Table 6‐9 Retail: Water Supplies — Projected
Water Code Section 10631 (b)
Additio
nal
Detail
on
Water
Supply
Potable
or Non‐
Potable
(after
treatmen
t if
treated)
(OPTION
AL)
Drop
Down list
Projected Water Supply (Report to the Extent Practicable)
list
May use
each
category
multiple
times. These
are the only
water supply
categories
that will be
recognized
by the
WUEdata
online
submittal
2030 2035 2040 2045 2050 (opt)
Reasona
bly
Available
Volume
(AF)
Total
Entitlem
ent
(OPTION
AL)
See
'DWR
Notes'
below
(AF)
Reasona
bly
Available
Volume
(AF)
Total
Entitlem
ent
(OPTION
AL)
See
'DWR
Notes'
below
(AF)
Reasona
bly
Available
Volume
(AF)
Total
Entitlem
ent
(OPTION
AL)
See
'DWR
Notes'
below
(AF)
Reasona
bly
Available
Volume
(AF)
Total
Entitlem
ent
(OPTION
AL)
See
'DWR
Notes'
below
(AF)
Reasona
bly
Available
Volume
(AF)
Total
Entitlem
ent
(OPTION
AL)
See
'DWR
Notes'
below
(AF)
Add additional rows as needed
ter (not
desalinate Potable 600 600 600 600 600 600 600 600 600 600
water (not
desalinate Potable 2,222 8,200 2,383 8,200 2,556 8,200 2,742 8,200 2,942 8,200
Subtotal Potable
Subtotal Non-Potable
Total
DWR NOTES:
Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3.
Total Entitlement: e.g. Water Right, Groundwater Allocation, Contracted Amount.
NOTES:
Pa
g
e
| 37
Page | 38
6.3 Energy Use
Water Code Section 10631.2 (a)
In addition to the requirements of Section 10631, an urban water management plan shall include any
of the following information that the urban water supplier can readily obtain:
(1) An estimate of the amount of energy used to extract or divert water supplies
(2) An estimate of the amount of energy used to convey water supplies to the water treatment plants
or distribution systems
(3) An estimate of the amount of energy used to treat water supplies
(4) An estimate of the amount of energy used to distribute water supplies through its distribution
systems
(5) An estimate of the amount of energy used for treated water supplies in comparison to the amount
used for non-treated water supplies
(6) An Estimate of the amount of energy used to place water into or withdraw from storage
(7) Any other energy-related information the urban water supplier deems appropriate
The TWSD Treatment Plant’s Solar Energy System was installed in 2012 in order to defray utility costs
to operate the treatment facility. Power performance capabilities are monitored in real-time, and
monthly analysis is conducted. For the calendar year of 2020, on average the power demand for
operation of the treatment plant was completely provided by on-site solar. The months of June
through October are the highest months for power demand and on average the on-site solar
provides 80% of the demand with the other months of the year exceeding the demand by 40%
on average.
Page | 39
Optional Submittal Table O‐1B: Recommended Energy Reporting ‐ SINGLE DELIVERY
PRODUCT ‐ TOTAL UTILITY APPROACH
Water Delivery Product
drop down list
(If delivering more than one type of product
Potabl
e
Deliver
Only for Water Delivery Products Under the Urban
Water Supplier's Operational Control
Start Date of Reporting Period
Sum of All Water
Management
Processes
Non‐Consequential Hydropower End Date of Reporting Period
No
Units of Measure for Water AF Total Utility
See DWR NOTES
Hydropowe
r Net Utility
Volume of Water Entering Process
Energy Consumed (kWh)
Energy Intensity (kWh/vol. converted to MG)
DWR NOTES:
Total Utility:The volume of water entered in the “Total Utility” column should equal the volume of water entering the
distribution system (excluding recycled water); in most cases, this is the total volume calculated in UWMP Table 4-1:
2025 Actual Total Uses for Potable and Non-Potable Water. Note if recycled water is included in your Submittal Table 4-
Quantity of Self‐Generated Renewable Energy
Data Quality
Metered Data
Data Quality Narrative:
Both treatment plant energy used and solar energy produced are metered.
Narrative:
The TWSD treatment plant utilized 635,852 kwh. The solar production at the plant was 730,570 kwh, bringing the net
energy use to -94,718 kwh in 2025.
NOTES:
Page | 40
CHAPTER 7 – WATER SERVICE RELIABILITY AND DROUGHT RISK
ASSESSMENT
This chapter addresses the reliability of the District’s water supplies. Assessment of water supply
reliability is complex and dependent upon a number of factors, such as the number of water sources,
regulatory and legal constraints, hydrological and environmental conditions, climate change, and
expected growth, among other. Based on available historical information and projections of future
water uses, regulatory and legal constraints, and hydrological and environmental conditions,
including climate change, TWSD has made its best determination of the future reliability of the
District’s water supplies.
This chapter includes the following sections:
7.1 Water Service Reliability
7.2 Supply and Demand
7.2.1 Management Tools and Options
7.3 Drought Risk Assessment
In this 2020 UWMP, water supply reliability is evaluated in two assessments: 1) the Water Service
Reliability Assessment and 2) the Drought Risk Assessment (DRA). The Water Service reliability
assessment compares projected supply to projected demand for three sets of hydrological
conditions: a normal year, a single dry year, and a drought period lasting five consecutive years. The
DRA is a new requirement in the UWMP that assesses water supply reliability under a severe drought
period. The hydrologic conditions yielding the least supply are overlain the population estimates for
the next five consecutive years in order to simulate a five year drought period from 2021 to 2025.
Factors affecting reliability, such as climate change, regulatory requirements and localized watershed
conditions, are also considered to prepare more realistic assessments.
7.1 Water Service Reliability
Water Code Section 10635 (a)
Every urban water supplier shall include, as part of its urban water management plan, as assessment
of the reliability of its water service to its customers during normal, dry, and multiple dry water years.
This water supply and demand assessment shall compare the total water supply sources available to
the water supplier with the long-term total projected water use over the next 20 years, in five-year
increments, for normal water year, a single dry water year, and a drought lasting more than five
consecutive water years. The water service reliability assessment shall be based upon the information
compiled pursuant to Section 10631, including population projections within the service area of the
urban water supplier.
Page | 41
Optional Submittal Table 7‐1 Retail: Basis of Water Year Data (Reliability Assessment)
Year Type
Base Year If
not using a calendar year,
type in the last year of
the fiscal, water year, or
range of years, for
example, water year
2024-2025, use 2025
Available Supplies if
Year Type Repeats
quantification of
available supplies
is not compatible
with this table
and is provided
elsewhere in the
UWMP.
Location: [insert
location from
Quantification of available supplies is
provided in this table as either volume
only, percent only, or both.
Volume Available
(AF)
% of Average
Supply
Single-Dry Year 2013 2487 30%
DWR NOTES: Supplier may use multiple versions of Submittal Table 7-1 R if different water sources have different base
years and the supplier chooses to report the base years for each water source separately. If a Supplier uses multiple
versions of Submittal Table 7-1 R, in the "Note" section of each submittal table, state that multiple versions of Submittal
Table 7-1 R are being used and identify the particular water source that is being reported in each submittal table.
Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3. This
table reports the units of measure reported in Submittal Table 2-3.
NOTES:
The District’s surface water source is from the Feather River watershed above Lake Oroville, including
runoff from Concow Creek, which is stored in Concow Reservoir. The water is conveyed via Concow
Creek to Lake Oroville. Downstream from the Oroville Dam, water is moved through the SWP’s
facilities, including the Thermalito Complex (comprised of the Thermalito Diversion Pool and Power
Canal). The District draws its water from the Thermalito Power Canal to be treated at the District’s
WTP. Concow Reservoir provides the majority of the water needs for the District. Under normal
conditions, surface water is conveyed through the SWP facilities without issue with regard to supply
and reliability. However, in 1997 there was an occurrence when water from Lake Oroville had water
Page | 42
quality issues with regard to turbidity and the District was unable to draw water from the Thermalito
Power Canal. However, this issue was resolved as a result of the 2008 microfiltration system addition
at the WTP.
An average of approximately 14.5 percent of the District’s water is provided from the District’s four
groundwater wells). Groundwater is drawn from the East Butte Subbasin. Groundwater used by the
District is treated with sodium hypochlorite as a preventative procedure against possible biological
contamination. In the future, depending on climatic changes and drought conditions (discussed
further below), groundwater supplies may be subject to environmental and climatic issues that
reduce reliability.
The District recognizes that variations in weather can result in different quantities of water supplied
within the watershed. In some years, dry weather or drought conditions may occur which will result
in varying degrees of water shortage. The District also recognizes that future climate change may
impact the intensity and duration of future droughts.
7.2 Supply and Demand
Normal Year
Water supply and demand patterns change during normal, single dry, and multiple dry years. To
analyze these changes, the District relies on historical usage to document expected changes in future
usage in water demand; such as assuming a reduced demand during wet years or an initial increased
demand due to additional irrigation needs caused to dry conditions, followed by a decrease in
demand due to awareness of drought conditions.
Table 7-2, below indicates that supplies will be reliable throughout the planning horizon of the UWMP
and that no supply deficiencies are expected.
Submittal Table 7‐2 Retail: Normal Year Supply and Use Comparison
Water Code Section 10635 (a)
2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 (AF)
Supply totals
(autofill from Submittal
Table 6-9 R)
2,822 2,983 3,156 3,342 3,542
Use totals
(autofill from Submittal
Table 4-2 R)
2,223 2,383 2,557 2,743 2,942
Surplus/(shortfall) 599 600 599 599 600
DWR NOTES : Units of measure (AF, CCF, MG)
reported in Submittal Table 2-3.
NOTES:
Page | 43
Single Dry Year
In general and from operational records, the District’s demand had shown to decrease during a single-
dry year as compared to normal years. The water demand generally returns close to that of a normal
dry year, primarily due to maintenance of landscaping and other high water uses what would
normally be supplied by precipitation.
The District assumes that the total supply will equal the demand in all future years. Therefore, the
supply is 100 percent reliable in single dry years, as shown in Table 7-3.
Submittal Table 7‐3 Retail: Single Dry Year Supply and Use Comparison
Water Code Section 10635(a)
2030
(AF)
2035
(AF)
2040
(AF)
2045
(AF) 2050 (AF)
Supply totals 8,800 8,800 8,800 8,800 8,800
Use totals 2,222 2,383 2,556 2,742 2,942
Surplus/(shortfall) 6,578 6,417 6,244 6,058 5,858
DWR NOTES : Units of measure (AF, CCF, MG) must remain consistent throughout the
UWMP as reported in Submittal Table 2-3.
NOTES
Page | 44
Multiple Dry Years
Table 7-4 below contains supply and demand estimates for a multiple dry year scenario. These data
suggests that District has confidence that the water supply will exceed the water demand through a
multi-year drought.
Submittal Table 7‐4 Retail: Multiple Dry Years Supply and Use Comparison
Water Code Section 10635(a)
2030
(AF)
2035
(AF)
2040
(AF)
2045
(AF)
2050
(AF)
First year
Supply totals 8,800 8,800 8,800 8,800 8,800
Use totals 2,222 2,383 2,556 2,742 2,942
Surplus/(shortfall) 6,578 6,417 6,244 6,058 5,858
Second year
Supply totals 8,800 8,800 8,800 8,800 8,800
Use totals 2408 2583 2770 2972 3189
Surplus/(shortfall) 6,392 6,217 6,030 5,828 5,611
Third year
Supply totals 8,800 8,800 8,800 8,800 8,800
Use totals 2151 2307 2474 2655 2848
Surplus/(shortfall) 6,649 6,493 6,326 6,145 5,952
Fourth year
Supply totals 8,800 8,800 8,800 8,800 8,800
Fifth year
Supply totals 8,800 8,800 8,800 8,800 8,800
Use totals 2084 2235 2398 2572 2760
Surplus/(shortfall) 6,716 6,565 6,402 6,228 6,040
must remain consistent throughout the UWMP as reported in Submittal
Table 2-3.
NOTES: Based on the five driest years from historical record 2001‐2020, noted as 2007‐2011.
Page | 45
Management Tools and Options
Water Code Section 10620(f)
An urban water supplier shall describe in the plan water management tools and options used by that
entity that will maximize resources and minimize the need to import water from other regions.
The District has adopted a Water Shortage Contingency Plan that corresponds to specific levels of
water supply shortage, and thus promotes water conservation. At each higher stage the District will
become more aggressive in requiring water use reductions from its customers. These stages are
designed to guide District personnel in making informed decisions during water shortages.
7.3 Drought Risk Assessment
Water Code Section 10635(b)
Every urban water supplier shall include, as part of its urban water management plan, a drought risk
assessment for its water service to its customers as part of information considered in developing the
demand management measures and water supply projects and programs to be included in the urban
water management plan. The urban water supplier may conduct an interim update or updates to this
drought risk assessment within the five-year cycle of its urban water management plan update. The
drought risk assessment shall include each of the following:
(1) A description of the data, methodology, and basis for one or more supply shortage conditions that
are necessary to conduct a drought risk assessment for a drought period that lasts five consecutive
water years, starting from the year following when the assessment is conducted
(2) A determination of the reliability of each source of supply under a variety of water shortage
conditions. This may include a determination that a particular source of water supply is fully reliable
under most, if not all, conditions.
(3) A comparison of the total water supply sources available to the water supplier with the total
projected water use for the drought period.
(4) Considerations of the historical drought hydrology, plausible changes on projected supplies and
demands under climate change conditions, anticipated regulatory changes, and other locally
applicable criteria.
In 2004, the Butte County Board of Supervisors adopted the Drought Preparedness and Mitigation
Plan through Resolution 04-200. A major element of the Drought Preparedness and Mitigation Plan
was the creation of the Drought Task Force. Through the Drought Taskforce, the Board of Supervisors
receives recommendations on current conditions and actions that the county should take. Any time
the Drought Task Force is activated, TWSD will participate as a member of the public in order to obtain
and share any relevant data sets.
In accordance with Water Code Section 10612, the DRA is based on the five driest consecutive years
on record. Table 7-5 below incorporates 2020 consumption data, DOF/BCAG population estimates
for 2020-2040, and watershed yield.
Page | 46
Submittal Table 7‐5 Retail: Five‐Year Drought Risk
Assessment
Water Code Section 10635(b)(3)
Total Water Use (AF) 2,113
Total Supplies (AF) 8,800
Surplus/Shortfall w/o WSCP Action 6,687
Total Water Use (AF) 2,155
Total Supplies (AF) 8,800
Surplus/Shortfall w/o WSCP Action 6,645
2028 Total
Total Supplies (AF) 8,800
2029 Total
Surplus/Shortfall w/o WSCP Action 6,558
2030 Total
DWR NOTES: Units of measure (AF, CCF, MG)
consistent throughout the UWMP as reported in Submittal Table
2-3.
NOTES:
Page | 47
CHAPTER 8 ‐ WATER SHORTAGE CONTINGENCY PLANNING
The WSCP is a detailed proposal for how a supplier intends to act in the case of an actual water
shortage condition. This plan is part of good drought policy even if a supplier’s water supply appears
to have low probability of shortage conditions, as it improves preparedness for droughts and other
impacts on water supplies. This WSCP anticipates a water supply shortage and provides pre-planned
guidance for managing and mitigating a supplier’s shortage. A well-structured WSCP allows real-time
water supply availability assessment and structured steps designed to respond to actual conditions,
to allow for efficient management of any shortage with predictability and accountability. In severe
drought conditions, a supplier’s WSCP serves as its road map for action for how to proceed through
various levels of shortage.
Water Code Section 10632.3
It is the intent of the Legislature that, upon proclamation by the governor of a state of emergency
under the California Emergency Services Act (Chapter 7 (commencing with section 8550) of Divisions
1 of Title 2 of the Governmental Code) based on drought conditions, the board defer to
implementation of locally adopted water shortage contingency plans to the extent practicable.
As Part of its UWMP, Water Code Section 10632 requires suppliers to prepare and adopt a WSCP that
consists of each of the following elements:
8.1 Water Supply Reliability Analysis
8.2 Annual Water Supply and Demand Assessment Procedures
8.3 Six Standard Water Shortage Stages
8.4 Shortage Response Actions
8.4.1 Demand Reduction
8.4.2 Supply Augmentation
8.4.3 Operational Enhancements
8.4.4 Rationing Stages to Address Water Supply Shortages
8.4.5 Emergency Response
8.4.6 Seismic Risk Assessment and Mitigation Plan
8.5 Communication Protocols
8.6 Compliance and Enforcement
8.7 Legal Authorities
8.8 Financial Consequences of WSCP Activation
8.9 Monitoring and Reporting
8.10 WSCP Refinement Procedures
8.11 Special Water Feature Distinction
8.12 Plan Adoption, Submittal, and Availability
8.1 Water Supply Reliability Analysis
Water Code Section 10632 (a)(1)
The Analysis of water supply reliability conducted pursuant to Section 10635.
The District’s surface water source is from the Feather River watershed above Lake Oroville, including
runoff from Concow Creek, which is stored in Concow Reservoir. The water is conveyed through
Page | 48
SWP’s facilities, including the Thermalito Complex (comprised of the Thermalito Diversion Pool and
Power Canal). The District draws it water from the Thermalito Power Canal to be treated at the
District’s WTP. Concow Reservoir provides the majority of the water needs for the District. An average
of approximately 14.5 percent of the District’s water is provided from the District’s four groundwater
wells. Ground water is drawn from the East Butte Subbasin.
In the future, considering drought conditions, reservoir and ground water supplies are projected to
be -adequate and reliable to meet the current and projected demand through 2045.
8.2 Annual Water Supply and Demand Assessment Procedures
Water Code Section 10632 (a)(2)
The procedures used in conducting an annual water supply and demand assessment that include, at
a minimum, both of the following:
(A) The written decision-making process that an urban water supplier will use each year to determine
its water supply reliability.
(B) The key data inputs and assessment methodology used to evaluate the urban water supplier’s
water supply reliability for the current year and one dry year, including all of the following:
(i) Current year unconstrained demand, considering weather, growth, and other influencing factors,
such as policies to manage current supplies to meet demand objectives in future years, as applicable.
(ii) Current year available supply, considering hydrological and regulatory conditions in the current
year and one dry year. The annual supply and demand assessment may consider more than one dry
year solely at the discretion of the urban water supplier.
(iii) Existing infrastructure capabilities and plausible constraints.
(iv) A defined set of locally applicable evaluation criteria that are consistently relied upon for each
annual water supply demand assessment
(v) A description and quantification of each source of water supply
Water Code Section 10632.1
An urban water supplier shall conduct an annual water supply and demand assessment pursuant to
subdivision (a) of Section 10632 and, on or before July 1 of each year, submit an annual water shortage
assessment report to the department with information for an anticipated shortage, triggered
shortage response actions, compliance and enforcement actions, and communication actions
consistent with the supplier’s water shortage contingency plan. An urban water supplier that relies
upon the Bureau of Reclamation shall submit its annual water supply and demand assessment within
14 days of receiving its final allocations, on or by July 1 of each year, whichever is later.
If the available water supply continues to remain greater than customer demand, no further action
will be required. However, if in any given year, the typical customer demand appears to be greater
than available supply, the TWSD Board of Directors may enact any stage of the Water Shortage
Contingency Plan (WSCP) by adopting a resolution in response to local or regional water supply
conditions. Several data sources will be consulted, including but not limited to, internal and external
hydraulic data, as well as all customer consumption records. The WSCP may be enacted based on a
number of conditions, including:
• An actual or potential local water supply restriction or emergency affecting the TWSD system;
Page | 49
• A collective recommendation from Butte County Water and Resource Conservation and the
City of Oroville;
• A formal water supply shortage notification by the Governor;
The Conservation Stages will normally be implemented in a progressive manner; however I may be
necessary for the District to skip stages in the use reduction plan in response to catastrophic supply
reductions. In general, conservation/use reduction levels will be set according to the anticipated
reduction in available water supplies.
The District takes seriously the charge to protect the resource for all available beneficial uses, and
will continue to advance internal abilities to accurately conduct Annual Water Supply and Demand
Assessments over the course of the next five years. At such time that the Department of Water
Resources publishes its stand-alone guidance document the District will follow that framework, in the
meantime, this WSCP outlines District specific procedures for conducting the Annual Assessment.
8.3 Six Standard Water Shortage Stages
Water Code Section 10632(a)(3)
(A) Six standard water shortage levels corresponding to progressive ranges of up to 10, 20, 30, 40,
and 50 percent shortages and greater than 50 percent shortage. Urban water suppliers shall define
these shortage levels based on the suppliers water supply conditions, including percentage reductions
in water supply, changes in groundwater levels, changes in surface elevation or level of subsidence,
or other changes in hydrological or other local conditions indicative of the water supply available for
use. Shortage levels shall also apply to catastrophic interruption of water supplies, including, but not
limited to, a regional power outage, an earthquake, and other potential emergency events.
(B) An urban water supplier with an existing water shortage contingency plan that uses different
water shortage levels may not comply with the requirement in subparagraph (A) by developing and
including a cross-reference relating its existing categories to the six standard water shortage levels.
Each of the below listed water shortage responses is intended to involve District customers in the
process of reducing consumer demand during years of diminished supply due to reduced
precipitation or any other event that could significantly reduce supply.
Page | 50
Submittal Table 8‐1
Water Shortage Contingency Plan Levels
Shortage
Level
Percent
Shortage Range
Shortage Response Actions
(Narrative description)
1 Up to 10% implemented. Maintain an ongoing public information campaign
such as "Water Wise" informational handouts. Maintain school
2 Up to 20%
Increase and continue all actions from level 1. There shall be no hose
washing of sidewalks, walkways, buildings, walls, patios, driveways,
parking areas or other paved surfaces, except to eliminate dangerous
conditions for the public. Washing of motor vehicles, trailers, boats,
and other equipment shall be done with hand held bucket and hose
equipped with a positive shut-off nozzle for rinses. All water users
shall promptly repair all leaks. Outside water uses between hours of
12:00 noon and 6:00 pm will be prohibited. Use of potable water in
fountain or decorative water fixtures will be prohibited unless the
fixture has a water circulation system. Monitor water use for
compliance with reduction targets.
3 Up to 30%
Restriction in levels 1 and 2 shall be in effect, except that the
restrictions on watering lawn, landscape, or other turf area shall be
modified to allow watering every third day, except between the
hours of 12:00 noon to 6:00 PM. The use of water from fire hydrants
shall be limited to fire fighting and related activities and other uses
of water for municipal purposes shall be limited to activities
necessary to maintain the public health, safety, and welfare.
4 Up to 40%
Restrictions listed in levels 1-3 shall be in effect, except that there
shall be no residential outside watering of lawn, landscaping, and
other turn areas at any time.
5 Up to 50%
Restrictions listed in levels 1-4 shall be in effect. Commercial
nurseries, schools, parks, and other public open spaces and
landscaped areas shall be prohibited from watering lawn,
landscaping, and other turf areas more often than every third day
6 >50%
Discontinue service for repeat offenders. Monitor water use weekly
for compliance with reduction targets. Prohibit potable water use for
landscape irrigation.
Page | 51
8.4 Shortage Response Actions
Water Code Section 10632 (a)(4)
Shortage response actions that align with the defined shortage levels and include, at a minimum, all
of the following:
(A) Locally appropriate supply augmentation
(B) Locally appropriate demand reduction action to adequately respond to shortages
(C) Locally Appropriate operational changes
(D) Additional, mandatory prohibitions against specific water use practices that are in addition to
state-mandated prohibitions and appropriate to the local conditions
(E) For each action, an estimate of the extent to which the gap between supplies and demand will be
reduced by implementation of the action
8.4.1 Supply Augmentation
The following Supply Augmentation Actions, found in Table 8.2, correspond to the six water shortage
levels outlined in the above section.
Submittal Table 8‐2 Retail: Supply Augmentation and Other Actions
Water Code Section 10632(a)(4)(A),(C) and (E)
Yes Is the Supplier completing this table using the standard six levels? (yes/no)
Shortage
Level
Supply Augmentation Methods
and Other Actions by Water
Supplier Drop down list
These are the only categories that will
be accepted by the WUEdata online
submittal tool
How much is this going to reduce
the shortage gap?
Additional Explanation or Reference
(OPTIONAL) Volume or
Percentage
Drop down
Shortage Gap
Reduction Value
(May be a range)
(AF)
1 Expand Public Information
Campaign Percentage 5
3 Implement or Modify Drought
Rate Structure or Surcharge Percentage 6
DWR NOTES: Units of measure (AF, CCF, MG)
Page | 52
8.4.2 Demand Augmentation
The following Demand Reduction Actions, found in Table 8.3, correspond to the six water shortage
levels outlined in the above section.
Submittal Table 8‐3 Retail: Demand Reduction Actions
Water Code Section 10632(a)(4)(B),(D), and (E)
Yes Is the Supplier completing this table using the standard six levels? (yes/no)
Shortage
Level
Demand Reduction
Actions
Drop down list
These are the only
categories that will be
accepted by the WUEdata
online submittal tool.
Select those that apply.
How much is this going to
reduce the shortage gap?
Additional Explanation or
Reference
(OPTIONAL)
Penalty,
Charge, or
Other
Enforcement?
For Retail
Suppliers Only
Drop Down List
Volume or
Percentage
Drop down
Gap
Reduction
Value
(May be a
1 Expand Public
Information Campaign Percentage 5 No
2 Percentage 1 to 3 No
2 Increase Frequency of
Meter Reading Percentage 2 No
2 landscape irrigation to Percentage 4 Yes
3 landscape irrigation to Percentage 6 More stringent timing reductions Yes
3 landscape irrigation to Percentage 8 Yes
4 landscape irrigation Percentage 6 Yes
5 landscape restriction or Percentage 6 Yes
6 Other Percentage 10 Yes
DWR NOTES: Units of measure (AF, CCF, MG)
Page | 54
8.4.3 Supply Augmentation
The District has completed multiple demand and supply assessment scenarios, and at this time, none
of those scenarios would require supply augmentation.
8.4.4 Operational Enhancements
The District continues to implement water conservation and water loss improvements. Improved
monitoring, analysis and tracking of system operations and customer usage will continually improve
the quality of annual water reliability assessments. During time of supply shortage, the District will
reduce system flushing, increase hydrant and filling station security, and intensify the meter
calibration program.
8.4.5 Rationing Stages to Address Water Supply Shortages
As a water purveyor, the District must provide the minimum health and safety water needs of the
community. Although the District has adequate supplies to serve its customers even if the available
supply is reduced to 50 percent of its total surface and groundwater supplies. However, the District
believes that it is important to respond to regional and state wide water conditions and use water
wisely.
The District has adopted a Water Shortage Contingency Plan that corresponds to specific levels of
water supply shortage, and thus promotes water conservation. At each higher stage the District will
become more aggressive in requiring water use reductions from its customers. The decision to enter
a new stage will be made by careful consideration of a variety of factors including supply, availability
of alternative supplies, time of year, and regional coordinated activities. These stages are designed
to guide District personnel in making informed decisions during water shortages. A certain amount
of flexibility is built in to the stages to allow for the unique characteristics of each water shortage
event and the unique characteristics within the district.
Water Code 10632(a)(3)(B) authorizes suppliers to continue using their own water shortage levels
that may have been included in past WSCP. If the supplier chooses to continue to do so in its new
WSCP, it must include a narrative or graphic describing the supplier’s water shortage levels in
relationship to the six standard water shortage levels prescribed by statue. In other words, the
supplier must provide a crosswalk that clearly translates the supplier’s water shortage levels to those
mandated by statue.
UWMP Level
Page | 55
In Stages I and II shortages, customers may adjust their interior or outdoor water use (or both), in
order to meet the voluntary water reduction goal. These water conservation activities are consistent
with the State Water Resources Control Board’s proposed Emergency Regulations regarding
residential water use in drought conditions.
Under Stage III, mandatory rationing programs would occur. The District has determined that a
reduction of 30% would be required; that amount of water is sufficient for essential interior water
needs with limited habitat such as trees, shrubs, and other landscape plantings, and residential grass
will be to no more than two irrigations per week. To qualify for limited irrigation, all plumbing fixtures
within the facility would be changed to low or ultra-low flow.
Under Stage IV mandatory rationing, which is likely to be declared only as the result of a prolonged
water shortage or as a result of a disaster, all habitat irrigation will cease and the health and safety
allotment would be reduced to 50 Percent of average use if the water stage should drop below 45
percent. This allotment still provides enough water for essential interior water use, plus a minimal
amount of outside use.
8.4.6 Emergency Response
In addition to drought conditions, there are other triggers that may result in a partial loss of water
supply due to mechanical failure resulting from natural disasters, chemical contamination, or other
water quality issues.
The steps that Thermalito Water and Sewer District has taken to prepare for a catastrophic water
supply interruption are summarized below:
1. Designed all well site infrastructure and water treatment facilities to latest UBC code.
2. Have emergency disinfection products and procedures available in case of contamination from
flooding or loss of use of the surface water treatment plant facility.
3. Continue to periodically test and maintain emergency backup generators, and annually review
interties with equipment rentals for first access of generators when in state of emergencies.
The District has developed an Emergency Disaster and Response Plan. This plan sets forth the
necessary manpower, equipment and other resources to effectively respond to various disasters. The
District also has an intertie agreement with California Water Service Company (CalWater) to provide
mutual assistance during water shortage emergencies. The District has developed other emergency
plans with the Department of Health Services, California Office of Emergency Services, and Butte
County Office of Emergency Services. The City of Oroville Disaster Plan and the District Emergency
Disaster and Response Plan Include the Following elements:
• Contamination of Water Systems
• Structural Damage from Explosive Device
• Chemical Release
• Power Outage
• Natural Events
• Water Supply Interruption
Page | 56
The four most likely scenarios for catastrophic water supply interruption for the District are fire,
earthquake, flooding, and power outages. Provided below is a brief discussion of the actions that
would be taken if there is a reduction in water supplies resulting from a catastrophic event.
Fire
In the event of a major fire, the District’s water treatment and distribution storage tanks will be
operated at maximum capacity.
Flooding
Flooding is a possibility in Thermalito if there should be a topping or catastrophic damage to the
Oroville Dam. One danger from flooding is contamination of drinking water. The District employs
disinfection procedures and stores disinfection supplies in case the drinking water system becomes
contaminated. Another impact of severe flooding is that groundwater pumping and treatment
equipment could become damaged. Evaluation, repair and replacement of groundwater pumping
and treatment equipment are part of the District’s emergency response protocol.
Reservoir Contamination
If contamination of the District’s surface water supply (from Concow Reservoir via Lake Oroville)
should occur, the District would implement rationing, activate the intertie agreement with Cal Water,
and start pumping from the District’s wells.
Major Power Outages
The District is able to operate, at full capacity, the raw water pump station and water treatment plant
during power outages using a 750 KVA diesel generator. External electrical power provisions are
provided at each well site and rental generators can be used at the District’s wells to provide
groundwater if needed.
8.4.7 Seismic Risk Assessment and Mitigation Plan
In the event of a major earthquake where significant portions of the distribution system or treatment
facilities are damaged, District crews or contractors will work on isolating and rerouting water
supplies.
In the event that the District’s raw water reservoir is damaged beyond use, the District would procure
water from the Butte County water right. One of the first things the District would do is flush all wells
for water purity and pumping ability. All wells that were able to provide water would be put on-line.
If available, the District would activate the intertie agreement with California Water Service Company
(Cal Water). Construction of this interconnection was completed in early 2002. The intertie with Cal
Water has a maximum capacity of 750 gallons per minute (gpm) or 3.3 AF/day.
During disasters or large- scale incidents, the Butte County Office of Emergency Management (OEM)
coordinates the overall response through the Emergency Operations Center (EOC). When activated,
the OC provides a central location for responding and supporting agencies to collaborate response
and recovery efforts in order to effectively and efficiently provide information and deploy resources.
In non-disaster times, the Butte County EOM supports and coordinates disaster planning, community
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preparedness, mitigation, and training. TWSD participated in the 2019 update of the Butte County
Local Hazard Mitigation Plan (LHMP) update, and the hazard mitigation planning elements specific to
TWSD are incorporated in the plan as Annex G.
8.5 Communication Protocols
Water Code Section 10632 (a)(5)
Communication protocols and procedures to inform customers, the public, interested parties, and
local, regional, and state governments, regarding, at a minimum, all of the following:
(A) Any current or predicted shortages as determined by the annual water supply and demand
assessment described pursuant to section 10632.1
(B) Any shortage response actions triggered or anticipated to be triggered by the annual water supply
and demand assessment described pursuant to Section 10632.1
(C) Any other relevant communications
This section lists a number of strategies that the Agency will employ to communicate with customers,
land use and planning entities for the City of Oroville, and County of Butte, as well as community
partners.
• Supply clear, consistent and understandable messaging to encourage increased voluntary
conservation via billing inserts and on the website.
• Collaborate with City and County partners to Development effective communications
regarding current conditions and specifically the District’s WSCP.
• Regularly communicate with local, state and other elected officials in the region about the
importance of achieving voluntary water conservation and encourage them to publicly
promote such efforts.
8.6 Compliance and Enforcement
Water Code Section 10632(a)(6)
For an urban retail water supplier, customer compliance, enforcement, appeal, and exemption
procedures for triggered shortage response actions as determined pursuant to Section 10632.2
In the event that restrictions or prohibitions set in place during a water shortage are violated,
penalties and charges would be implemented. The penalty would take effect when Prohibition Stages
II-IV are in effect and would invoke a drought rate or surcharge.
8.7 Legal Authorities
Water Code Section 10632 (a)(7)
(A) A description of the legal authorities that empower the urban water supplier to implement and
enforce its shortage response actions specified in paragraph (4) that may include, but are not limited
to, statutory authorities, ordinances, resolutions, and contract provisions.
(B) A Statement that an urban water supplier shall declare a water shortage emergency in accordance
with chapter 3 (commencing with Section 350) of Division 1. [See below]
(C) A statement that an urban water supplier shall coordinate with any city or county within which it
provides water supply services for the possible proclamation of a local emergency, as defined in
Section 8558 of the Government Code.
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California Water Code Chapter 3 Sections 350-359 outlines that “ The governing body of a distributor
of a public water supply, whether publicly or privately owned and including mutual water company,
shall declare a water shortage emergency condition to prevail within the area served by such
distributor whenever it finds and determines that the ordinary demands and requirements of water
consumers cannot be satisfied without depleting the water supply of the distributor to the extent
that there would be insufficient water for human consumption, sanitation, and fire protection.”
8.8 Financial Consequences of WSCP Activation
Water Code Section 10632 (a)(8)
A description of the financial consequences of, and responses for, drought conditions, including, but
not limited to, all of the following:
(A) A description of potential revenue reductions and expense increases associated with activated
shortage response actions described in paragraph (4)
(B) A description of mitigation actions needed to address revenue reductions and expense increases
associated with activated shortage response actions described in paragraph (4)
(C) A description of the cost of compliance with Chapter 3.3 (commencing with Section 365) Divisions
1. [Retail urban suppliers only]
During water supply shortages the District would expect to see a reduction in revenue. Since all of
the District’s customers are metered, revenue impacts from decreasing consumer use would occur.
Furthermore, although expenditures on water purchases would decrease, administration and
operations and maintenance expenses for the District would remain the same, or possibly increase
with additional operations and administrative activity. The amount of this reduction would depend
on the total amount of water not being used and the price not being charged.
The District has established operating reserves which would fund the majority of the financial impact.
After a water shortage has developed, the District may use a combination of rate adjustments,
operational resource evaluations, and postponement of capital projects to address revenue impacts
of the reductions in consumption that the contingency fund cannot meet.
8.9 Monitoring and Reporting
Water Code Section 10632(a)(9)
For an urban water supplier, monitoring and reporting requirements and procedures that ensure
appropriate data collected, tracked, and analyzed for purposes of monitoring customer compliance
and to meet state reporting requirements.
Thermalito Water and Sewer will continue to track monthly production and consumption data, along
with monitoring hydrologic conditions throughout the watershed and Sacramento Valley. Staff will
present the annual Water Supply Reliability Analysis to the Board of Directors at their publicly held
meeting each year.
8.10 WSCP Refinement Procedures
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Water Code Section 10632(a)(10)
Reevaluation and improvement procedures for systematically monitoring and evaluating the
functionality of the water shortage contingency plan in order to ensure shortage risk tolerance in
adequate and appropriate water shortage mitigation strategies are implemented as needed.
The TWSD Board of Directors maintains a draft resolution declaring the Water Shortage Contingency
Program. This resolution remains an effective tool that may be implemented as deemed necessary
by the Board of Directors, or in conjunction with a declared State of Emergency by the County of
Butte or the State.
TWSD will continually make refinements to the WSCP based on real-time hydrologic conditions. As
the current and historical conditions can only be used as a predictive tool, it will be necessary to make
adjustments as more data is accumulated. Any updates to the WSCP will be presented to the Board
of Directors and approved and adopted as required.
8.11 Special Water Feature Distinction
Water Code Section 10632(b)
For purposes of developing the water shortage contingency plan pursuant to subdivision (a), an urban
water supplier shall analyze and define water features that are artificially supplied with wither,
including ponds, lakes, waterfalls, and fountains, separately from swimming pools and spas, as
defined in subdivision (a) of Section 115921 of Health and Safety Code.
TWSD will consider water features separately from pools and spas in the WSCP. Non-pool or non-spa
water features such as decorative water features and recreational water features may use or be able
to use recycled water, whereas pools and spas much use potable water for health and safety
consideration. Limitations to pools and spas may require different considerations compared to non-
pool or non-spa water features.
8.12 Plan Adoption, Submittal, and availability
Water Code Section 10632 (c)
The urban water supplier shall make available the water shortage contingency plan prepared
pursuant to this article to its customers and any city or county within which it provides water supplies
no later than 30 days after adoption of the water shortage contingency plan.
TWSD will follow these steps prior to the adoption of the WSCP:
1. The Agency will provide notification to customers, City and County officials and the public at large
by publishing the notice of a public hearing in a local newspaper for two consecutive weeks prior to
the hearing.
2. The District will hold a public hearing to gather public feedback.
3. Following the hearing, or at a subsequent Board meeting, the Board of Directors shall adopt the
WSCP.
4. The District will make the WSCP publicly available on the District website no later than 30 days
after it is adopted.
5. Each time the District makes announcements regarding the WSCP, the above process shall be
followed.
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CHAPTER 9 – DEMAND MANAGEMENT MEASURES
Demand management is an integral part of sustainability managing water resources in California. As
population continues to grow, demand for water typically increases. This increase in water demand,
coupled with reduced supplies or shifts in supplies because of climate change and other factors, can
jeopardize water reliability if no mitigation is in place. To better prepare for and reduce effect caused
by these situations, implementing water use-DMMs that help lower demands can improve water
service reliability and help meet state and regional water conservations goals. Reducing demands can
also benefit suppliers by reducing energy costs, putting the supplier in a better position for its future
water security.
This chapter contains the following sections:
9.1 Demand Management Measures for Retail Suppliers
9.1.1 Metering
9.1.2 Public Education and Outreach
9.1.3 Water Conservation Program Coordination and Staffing Support
9.1.4 Water Waste Prevention Ordinances
9.2 Reporting Implementation
9.2.1 Implementation to Achieve Water Use Targets
9.3 Water Use Objectives
9.1 Demand Management Measures for Retail Suppliers
Water Code Section 10631
(e) Provide a description of the supplier’s water demand management measures. The description shall
include all of the following:
(1)(A) For an urban retail water supplier, as defined in Section 10608.12, a narrative description that
addresses the nature and extent of each water demand management measure implemented over the
past five years. The narrative shall describe the water demand management measure that the supplier
plan to implement to achieve its water use targets pursuant to Section 10608.20
(B) The narrative pursuant to this paragraph shall include descriptions of the following water demand
management measures:
(i) Water waste prevention ordinances
(ii) Metering
(iii) Conservation Pricing
(iv) Public education
(v) Programs to assess and manage distribution system real loss
(vi) Water conservation program coordination and staffing support
(vii) Other demand management measures that have a significant impact on water use measured in
gallons per capita per day, including innovative measures, if implemented
9.1.1 Metering
Metering with Commodity Rates for All New Connections and Retrofit of Existing Connections
The District has historically required meters to all services since 1955 and will continue this
requirement into the future. The customer is billed a service charge with each billing and a
consumption charge for all water passing through the meter.
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At the present the District has 3,134 accounts and all are metered. The District replaced over 2,500
meters from 1999 to the present with the remaining 634 meter of ages ranging between 15 to 58
years old.
The District has a single billing rate for all customers and has found that raising the single rate has
generated great water conservation practices by its customers. In the event of a water shortage the
Board is studying a tiered system that raises the billing units by as much as 25% when a single user
exceeds 1200 billing units. For multiple dwelling unit accounts there will be a dwelling unit factor
applied per 1000 billing units. There are a lot of issues to consider on this, but the primary issue will
establishing a life line level that is equitable for all. The Board is studying and has required more fact
finding before there is any action on this issue.
9.1.2 Public Education and Outreach
Public Information Programs
The District promotes water conservation several ways. The primary source of conservation
information to our customers is through our website and bulletin board in the office. The District also
provides information to new customers encouraging water conservation. A section is dedicated to
conservation and one of our most popular sites is the drought tolerant plant section.
9.1.3 Water Conservation Program Coordination and Staffing Support
Designation of an Official Water Conservation Coordinator
The District is not a large organization and the District’s Compliance Supervisor under direct
supervision under the District Manager will coordinate the water conservation activities of the
District.
The District will continuously evaluate the need to provide additional resources beyond the use of
the Compliance Supervisor and District Manager
9.1.4 Water Waste Prevention Ordinances
Water Survey Programs for Single-Family Residential and Multifamily Residential Customers
Since 2004, the District has provided water audits at the request of customers. The public has the
opportunity on the District’s website to schedule a water audit. This is available to all types of users
in the District.
The District issues letters to customers that show a higher than normal consumption use indicating
they may have a problem. The letter offers a water audit to these customers and provides information
on water conservation. We conduct an average of three audits per year.
Our Utility Billing Supervisor and Compliance Supervisor conduct the audits. The customers are
provided with a bucket for measuring use, a low flow showerhead, a low flow hose nozzle, toilet tank
dye tablets, a toilet tank bag, and a conservation fact sheet. An interior check for leaks is conducted
with a review of the customer’s irrigation system.
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The District will continue to offer this program in the future. It is too difficult to quantify the savings,
but the positive public relations the audits supply are worth the expense to the District.
9.2 Reporting Implementation
System Water Audits, Leak Detection, and Repair
The District’s monthly Superintendents report tracks and updates on a monthly basis the
unaccounted water in the District. The percentage of lost water is consistently low due to a 13 year
service line replacement program and meter replacement program. The District’s main water loss
sources are the old galvanized service lines and the un-accounted water loss due to old meter
inaccurate readings.
The District has continued to focus on service line replacement, and meter replacement. The District
started utilizing meters in 1955 and did not have a meter replacement program until 1999. Over the
years the meter replacement program has shown a greater reduction of lost water than any other
improvement implemented.
Monthly Superintendent reports with water system audits, leak repair, and minor mainline
replacements will continuously be implemented at the District. The replacement of aging facilities is
a primary focus of the District for the foreseeable future.
9.2.1 Implementation to Achieve Water Use Targets
All DMMs described above are meant to contribute to the District’s effort to comply with its SB x7-7
2020 target GPCD.
9.3 Water Use Objectives
TWSD will continue to meter and track water loss, coordinate public information programs targeting
customer conservation, and determine where infrastructure improvements should be prioritized.
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CHAPTER 10 ‐ PLAN ADOPTION, SUBMITTAL, AND IMPLEMENTATION
This chapter provides guidance for addressing the Water Code requirements for a public hearing, the
Urban Water Management Plan and Water Shortage Contingency Plan adoption process, submitting
and adopted UWMP and WSCP and making these plans available to the public, plan implementation,
and the process for amending an adopted UWMP and WSCP.
This chapter includes the following sections:
10.1 Inclusion of All 2020 Data
10.2 Notice of Public Hearing
10.2.1 Notice to Local Government
10.2.2 Notice to the Public
10.3 Public Hearing and Adoption
10.4 Plan Submittal
10.4.1 Submitting the UWMP to DWR
10.4.2 Submitting the UWMP to the CA State Library
10.4.3 Submitting the UWMP to Cities and Counties
10.5 Public Availability
10.6 Notification to Public Utilities Commission
10.7 Amending an Adopted UWMP and/or WSCP
10.1 Inclusion of All 2025 Data
This UWMP contains all of the water use and planning data for the entire calendar year of 2025.
10.2 Notice of Public Hearing
10.2.1 Notice to Local Government
Water Code Section 10621(b)
Every urban water supplier required to prepare a plan shall… at least 60 days prior to the public
hearing on the plan… notify any city or county within which the supplier provides water supplies that
the urban water supplier will be reviewing the plan and considering amendments or changes to the
plan.
Water Code Section 10642
The urban water supplier shall provide notice of the time and place of a hearing to any city or county
within which the supplier provides water supplies. Notices by a local public agency pursuant to this
section shall be provided pursuant to Chapter 17.5 (commencing with Section 7290) of Division 7 of
Title 1 of the Government Code. A privately owned water supplier shall provide an equivalent notice
within its service area…
Government Code Section 7291
…every local public agency… serving a substantial number of non-English-Speaking people, shall
employ a sufficient number of qualified bilingual persons in public contact positions or as interpreters
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to assist those in such positions, to ensure provision of information and services in the language of the
non-English-Speaking person.
There are two audiences to be notified for the public hearing: cities and counties, and the general
public. On 8/25/2021 the District notified Butte County Water and Resource Conservation as well as
City of Oroville Administration, and Butte County Development Services that it was developing a 2020
UWMP. Additionally, the preparation notice was sent to local wastewater collection and treatment
agencies. This was in advance of the 60-day notification prior to a public hearing requirement.
Submittal Table 10‐1 Retail: Notification to Cities and
Counties
Water Code Section 10621(b) and 10642
City Name 60 Day Notice
Drop Down (yes/no)
Notice of Public
Hearing
Drop Down (yes/no)
City of Oroville Yes Yes
County Name
Drop Down List 60 Day Notice
Drop Down (yes/no)
Notice of Public
Hearing
Drop Down (yes/no)
Add additional rows as needed
Butte County Yes Yes
NOTES:
10.2.2 Notice to the Public
Water Code Section 10642
Prior to adopting either [the plan or water shortage contingency plan], the urban water supplier shall
make both the plan and the water shortage contingency plan available for the public inspection and
shall hold a public hearing or hearings thereon. Prior to any of these hearings, notice of the time and
place of the hearing shall be published within the jurisdiction of the publicly owned water supplier
pursuant to Section 6066 of the Government Code [see below]. The urban water supplier shall provide
notice of the time and place of a heating to any city or county within which the supplier provides water
supplies.
Government Code Section 6066
Publication of notice pursuant to this section shall be once a week for two successive week. Two
publications in a newspaper publishes once a week or oftener, with at least five days intervening
between the respective publication dates not counting such publications dates, are sufficient. The
period of notice commences upon the first day of publication and terminates at the end of the
fourteenth day, including therein the first day.
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Notice to the public is included in the July 21, 2026 Board Agenda Packet.
The UWMP, along with the WSCP were both available for public access and inspection at the District’s
office at 410 Grand Avenue in Oroville, Ca. The document is also available to the public on the
District’s website at www.twsd.info, and the local library. Legal public notices were published in the
local newspapers and posted at local facilities. A copy of the Legal Notice and Affidavit of Publication
for the Public Hearing is attached as Appendix X.
10.3 Public Hearing and Adoption
Water Code Section 10642
Prior to adopting either, the ]plan or water shortage contingency plan], the urban water supplier shall
make both the plan and the water shortage contingency plan available for public inspection and shall
hold a public hearing or hearings thereon.
Water Code Section 10608.26(a)
In complying with this part, an urban retail water supplier shall conduct at least once public hearing
to accomplish all of the following:
(1) Allow community input regarding the urban retail water supplier’s implementation plan for
complying with this part.
(2) Consider the economic impacts of the urban retail water supplier’s implementation plan for
complying with this part.
(3) Adopt a method, pursuant to subdivision (b) of Section 10608.20 for determining its urban water
use target.
The public hearing for both the UWMP and the WSCP took place at the April 19, 2022 Board of
Directors meeting. The Agenda included the public hearing as an agenda item, and was properly
noticed as required of a public agency.
The Thermalito Water and Sewer District prepared this 2020 Urban Water Management Plan. A
public hearing for review of the Plans was held at the District Office on April 19.2022 at 2:00PM.
The 2020 UWMP and the WSCP were adopted by the District’s Board of Directors on XXX XX, 2021.
Attached as Appendix X are copies of the signed Resolution of Plan Adoption for both plans.
10.4 Plan Submittal
Water Code Section 10621(e)
Each urban water supplier shall update and submit its 2020 plan to the department by July 1, 20201
Water Code Section 10644(a)(1)
An urban water supplier shall submit to the department, the California State Library, and any city of
county within which the supplier provides water Supplies a copy of it plan no later than 30 days after
adoption.
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Water Code Section 10635(c)
The urban water supplier shall provide that portion of its urban water management plan prepared
pursuant to this article to any city or county within which it provides water supplies no later than 60
days after the submission of its urban water management plan.
10.4.1 Submitting the UWMP to DWR
After UWMP and WSCP adoption at the Jul 21, 2026 Board of Directors meeting, TWSD will
electronically submit the plans and all associated references to the WUE data portal. This electronic
submission will be completed on July 22, 2026
10.4.2 Submitting the UWMP to the CA State Library
On July 22, 2026, which is not later than 30 days after adoption at the July 21, 2026 public hearing, the
District will submit a CD or hardcopy of the adopted 2025 UWMP, including the adopted WSCP,
to the California State Library at:
California State Library Government Publication Section
Attn: Coordinator, Urban Water Management Plans
P.O. Box 942837 Sacramento, CA 94237-0001
10.4.3 Submitting the UWMP to Cities and Counties
No later than 30 days after adoption, the District will submit a copy of the adopted 2020 UWMP,
including the WSCP, to any city or county to which the supplier provides water. This copy may be in
an electronic format, which will satisfy Water Code Section 10635(b).
10.5 Public Availability
Water Code Section 10645
(a) Not later than 30 days after filing a copy of its plan with the department, the urban water supplier
and the department shall make the plan available for public review during normal business hours.
(b) Not later than 30 days after filing a copy of its water shortage contingency plan with the
department, the urban water supplier and the department shall make the plan available for public
review during normal business hours.
The Thermalito Water and Sewer District prepared this 2025 Urban Water Management Plan. A
public Hearing for review of the Plan was held at the District Office on July 21, 2026 and 2:00 PM.
The 2025 UWMP and WSCP were adopted by the District’s Board of Directors on July 21, 2026.
Attached as Appendix E are copies of the signed Resolution of the Plan Adoption for both Plans.
10.6 Notification to Public Utilities Commission
Water Code Section 10621 (c)
An urban water supplier regulated by the Public Utilities Commission shall include its most recent plan
and water shortage contingency plan as part of the supplier’s general rate case filings. Per Water
Code Section 10621(c), those Suppliers that are regulated by the California Public Utilities Commission
(CPUC) must submit their UWMP and WSCP to the CPUC as part of its general rate case filings.
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10.7 Amending an Adopted UWMP or Water Shortage Contingency Plan
Water Code Section 10621 (d)
The amendments to, or changes in, the plan shall be adopted and filed in the manner set forth in
Article 3 (commencing with Section 10640).
Water Code Section 10644(a)(1)
Copies of amendments or changes to the plans shall be submitted to the department, the California
State Library, and any city or county within which the Supplier provides water supplies within 30 days
after adoption.
Should TWSD amend either the adopted UWMP or WSCP, each of the steps nor notification, public
hearing, adoption, and submittal will be followed.
Appendix A: Water Shortage Contingency Plan
Water Shortage Contingency Plan
Law 10632: The plan shall provide an urban water shortage contingency analysis which includes each
of the following elements which are within the authority of the urban water supplier:
(a) Stages of action to be undertaken by the urban water supplier in response to water
supply shortages, including up to a 50 percent reduction in water supply, and an outline
of specific water supply conditions which are applicable to each stage.
Water Shortage Stages and Triggering Mechanisms
As a water purveyor, TWSD must provide the minimum health and safety water needs of the community
at all times. The water shortage response is designed to provide a minimum of 50% of normal surface and
groundwater supply during a severe or extended water shortage. The rationing program triggering levels
shown below were established to ensure this goal is met.
Although an actual shortage may occur at any time during the year, the District will use the critical
months of May through September to determine potential restrictions.
Table 12
Water Supply Shortage Stages and Conditions
RATIONING STAGES
Stage No. Water Supply Conditions on May 1st % shortage
Projected water deliveries for 2035 would be 3,252.6 acre feet
Impacts to Customers (refer to above Table 12)
In Stages I and II shortages, customers may adjust either interior or outdoor water use (or both), in order
to meet the voluntary water reduction goal.
Under Stage III, mandatory rationing programs would occur. The District has determined that a reduction
of 30% (Stage III) would be required; that amount of water is sufficient for essential interior water with
limited habitat such as trees, shrubs and other landscape plantings, and residential grass will be limited to
no more than two irrigations per week. To qualify for limited irrigation, all plumbing fixtures within the
facility would be changed to low or ultra-low flow.
Under Stage IV mandatory rationing, which is likely to be declared only as the result of a prolonged water
shortage or as a result of a disaster, all habitat irrigation will cease and the health and safety allotment
would be reduced to 50% of average use if the water stage should drop below 45%. This allotment still
provides enough water for essential interior water use, plus a minimal amount of outside use.
Restriction on the Use of Water By Stages
Stage I and II – 15 to 20% Reduction
1) There shall be no hose washing of sidewalks, walkways, buildings, walls, patios, driveways,
parking areas or other paved surfaces and walls, except to eliminate conditions dangerous to
public health or safety, or when required as surface preparation for the application of architectural
coating or painting.
2) Washing of motor vehicles, trailers, boats and other types of equipment shall be done
only with a hand-held bucket or a hose equipped with a positive shut-off nozzle for quick rinses.
The exception: washing may be done by a commercial car wash using recycled water.
3) All water users shall promptly repair all leaks from indoor and outdoor plumbing fixtures.
4) Outside water uses between the hours of 12:00 noon and 6:00 p.m. every day will be prohibited.
Stage III - 30% Reduction
1) Restrictions listed in Stage I and II shall be in effect, except that the restrictions on watering lawn,
landscape or other turf area shall be modified to allow watering every third day except between
the hours of 12:00 noon to 6:00 p.m.
2) The use of water from fire hydrants shall be limited to fire fighting and related activities and other
uses of water for municipal purposes shall be limited to activities necessary to maintain the public
health, safety and welfare.
Stage IV - 50% Reduction
1) Restriction listed in Stage III shall be in effect, except that there shall be no residential outside
watering of lawn, landscaping and other turf areas at any time.
2) Restrictions listed in Stages I, II, and III shall be in effect.
3) Commercial nurseries, schools, parks and other public open spaces and landscaped areas shall be
prohibited from watering lawn, landscaping and other turf areas more often than every third day
and between the hours of 6:00 a.m. and 6:00 p.m.
A water user may file an appeal for relief from any provisions of the various stages. The District manager
shall develop such procedures as he or she considers necessary to resolve such appeals and shall, upon the
filing by a water user of an appeal, take such steps as he or she deems reasonable to resolve the appeal.
Water Allotment Methods
Customer allotments are based on a three-year period. This gives the District a more accurate view of the
usual water needs of each customer and provides additional flexibility in determining allotments and
reviewing appeals. However, no allotment may be greater than the amount used in the most recent year of
the five-year base period.
It is the intent of the District to spread the reductions equally among all customers. Customers may be
notified of their classification and allotment by mail before the effective date of the Water Shortage
Emergency. New customers will be notified at the time the application for service is made. In a disaster,
prior notice of allotment may not be possible; therefore notice will be provided by other means. Any
customer may appeal the District's manager's classification on the basis of use or the allotment on the
basis of incorrect calculation.
Three-Year Minimum Supply
Law 10632: The plan shall provide an urban water shortage contingency analysis which includes each
of the following elements which are within the authority of the urban water supplier:
(b) An estimate of the minimum water supply available during each of the next three
water years based on the driest three-year historic sequence for the agency's water supply.
Three-Year Minimum Supply
The three-year minimum supply table shown below estimates the supply based on the historical three-
year driest on record. The three driest years on record correspond to the first three years of the multiple
dry years estimates shown in the tables at the beginning of the plan (2007-2009).
Table 13
Three-Year Estimated Minimum Water Supply-AF Year
Source Normal 2007 2008 2009
The groundwater supply is not included as there is no data to validate its capacity at this time.
Appendix B: UWMP NOTICE
5/20/2026
Thermalito Water and Sewer District
410 Grand Ave,
Oroville, CA 95965
NOTICE OF PREPARATION FOR 2020 URBAN WATER MANAGEMENT PLAN (UWMP).
The Urban Water Management Planning Act (California Water Code 10608-10656) requires that
Thermalito Water and Sewer Update its Urban Water Management Plan (UWMP) every 5 years.
Notice is hereby given that Thermalito Water and Sewer District (TWSD) will hold a public hearing
regarding review and adoption of its Urban Water Management Plan (UWMP). The UWMP documents
the Agency’s plans to ensure adequate water supplies to meet existing and future demands for water
under a range of water supply conditions, including water shortages.
Coordination with other water suppliers, cities, counties, and community organizations in the region is
an important part of the preparation of Thermalito Water and Sewer’s UWMP. In compliance with the
Water Conservation Act of 2009, a draft of the 2025 UWMP will be made available for public review and
a public hearing. The public hearing will be held as part of the TWSD’s Board of Directors regular
meeting on July 21, 2026. We will notify you when the draft is available for review, how to access it, and
details regarding the public hearing.
If you would like more information regarding our 2025 UWMP please contact:
Chris Heindell
Thermalito Water and Sewer District
Phone: (530) 533-0740
Email: Cheindell@twsd.info
Butte LAFCo
1453 Downer St #C
Oroville, CA 95965
Butte County Public Health Department
695 Oleander Ave
Chico, CA 95926
Butte County Department of Water Resources
308 Nelson Ave
Oroville, CA 95965
Butte County Development Services
7 County Center Drive
Oroville, CA 95965
City of Oroville
1735 Montgomery Street
Oroville, CA 95965
Lake Oroville Area Public Utility District
1960 Elgin St.
Oroville, CA 95966
South Feather Water & Power Agency
2310 Oro Quincy Hwy
Oroville, CA 95966
North Yuba Water District
8691 La Porte Rd
Brownsville, Ca 95919
California Water Service, Chico
2222 Dr. Martin Luther King Jr Pkwy
Chico, CA 95928
Sewerage Commission - Oroville Region
2880 S 5th Ave
Oroville, CA 95965
California Water Service, Oroville
1905 High St
Oroville, Ca 95965
Appendix C: Local Hazard Mitigation Plan 2024
Butte County TWSD Annex S-1
Local Hazard Mitigation Plan Update
September 2024
Annex S Thermalito Water and Sewer District
S.1 Introduction
This Annex details the hazard mitigation planning elements specific to the Thermalito Water and Sewer
District (TWSD or District), a previously participating jurisdiction to the 2019 Butte County Local Hazard
Mitigation Plan (LHMP) Update. This Annex is not intended to be a standalone document but appends to
and supplements the information contained in the Base Plan document. As such, all sections of the Base
Plan, including the planning process and other procedural requirements apply to and were met by the
District. This Annex provides additional information specific to TWSD, with a focus on providing
additional details on the planning process, risk assessment, and mitigation strategy for this District.
S.2 Planning Process
As described above, TWSD followed the planning process detailed in Chapter 3 of the Base Plan. In
addition to providing representation on the Butte County Hazard Mitigation Planning Committee (HMPC),
the District formulated their own internal planning team to support the broader planning process
requirements. Internal planning participants, their positions, and how they participated in the planning
process are shown in Table S-1. Additional details on Plan participation and District representatives are
included in Appendix A.
Table S-1 TWSD – Planning Team
Name Position/Title How Participated
Christopher Heindell District Engineer Meeting coordination, plan preparation and mitigation project
implementation/coordination
Jayme Boucher General Manager Meeting coordination, plan preparation and mitigation project
implementation/coordination
Carolyn Padilla Office Manager Mitigation project implementation and coordination
Coordination with other community planning efforts is paramount to the successful implementation of this
LHMP Update. This section provides information on how the District integrated the previously approved
2019 LHMP into existing planning mechanisms and programs. Specifically, the District incorporated into
or implemented the 2019 LHMP through other plans and programs shown in Table S-2.
Table S-2 2019 LHMP Incorporation
Planning Mechanism 2019 LHMP Was
Incorporated/Implemented In.
Details: How was it incorporated?
2021 Update to Emergency/Disaster Response
Plan
The hazards listed in the previous TWSD annex were reviewed, and
response plans for many of those hazards were formulated.
Butte County TWSD Annex S-2
Local Hazard Mitigation Plan Update
September 2024
S.3 Community Profile
The community profile for the TWSD is detailed in the following sections. Figure S-1 displays a District
map and the location of TWSD within Butte County.
Butte County TWSD Annex S-3
Local Hazard Mitigation Plan Update
September 2024
Figure S-1 TWSD
Butte County TWSD Annex S-4
Local Hazard Mitigation Plan Update
September 2024
S.3.1. Overview and Background
Located in southern Butte County, California, the Thermalito Water and Sewer District was established in
April 3, 1922 as Thermalito Irrigation District and supplied water to an area of approximately 3,164 acres
with a service population of approximately 360 properties owners. The District’s initial boundaries were
much larger but only 3,164 acres could be served with water by the existing distribution system. The
District was formed with the express purpose of providing agricultural water to the Thermalito community.
The District was authorized to operate by the California Water Code, Division 11, Section 20500 to 29978
derived from the 1897 Irrigation District law. The District was organized to bond itself to the extent of
$270,000.00 to finance the construction or purchasing the necessary irrigation canals and acquiring the
necessary property, water, water rights, reservoirs, reservoir sites and other property necessary for the
purposes of the District. On July 1, 2008 the District changed its name to Thermalito Water and Sewer
District.
In August 1923, for the sum of $10,000, the District purchased land from the Pacific Gas & Electric
Company for the purpose of development of a reservoir. Construction of the Concow Dam on Concow
Creek began in November of 1923 and was completed in December 1924. The Concow watershed was
chosen because it was part of the original water distribution system owned by Pacific Gas & Electric
Company and was not included when Thermalito Irrigation District incorporated. PG&E did not provide
the Wilnore/Concow water storage system, and it was essential the District acquire the old Wilnore dam
and land for the water rights needed. During the early years, Wilnore/Concow Reservoir water was used
almost solely for irrigation; almost all residences used the District water for domestic purposes. There were
a few private wells in the District, but the majority of residences could not afford to dig for water as the
hard pan layers under Thermalito made it cost prohibitive to dig.
The Concow Reservoir, also known as the Wilnore Reservoir, has a capacity of 7,225-acre feet. Under the
original appropriative water rights licenses issued in 1928 and 1929, TID/TWSD held title to 45% of the
water and the remaining 55% was held by TMID (Table Mountain Irrigation District). Water released from
the reservoir was diverted into the Wilnore Ditch through the Wilnore siphon under the West Branch of the
Feather River and into the Pacific Gas & Electric Company’s Miocene Ditch. The water was then used to
generate power at PG&E’s powerhouses at Lime Saddle and Coal Canyon and was conveyed from the Coal
Canyon powerhouse to the Miocene Ditch (also referred to as the Powers Canal, owned by California Water
Service), and delivered to the TID/TWSD service area at the site of the present water storage tank.
Construction of the Oroville Dam and appurtenant facilities of the State Water Project in the 1960’s
provided an alternative means of conveying the District’s Concow water to the service area. In 1965
TID/TWSD entered into an agreement with the California Department of Water Resources (DWR) to
release its share of Concow water into the West Branch of the Feather River, either by way of Concow
Creek or through the PG&E Lime Saddle power plant. In 1966 Oroville Dam and Thermalito Diversion
Dam were added to the water rights license as points of power diversion and re-diversion to the District.
The condition of the Wilnore and Spring Valley Ditch system gradually declined over the years until it
became so dry that its water retention capacity was questionable and seepage losses were becoming
prohibitive. TID/TWSD’s agreement with the Department of Water Resources was amended in 1971 to
allow delivery of Concow water via Concow Creek to Lake Oroville. The earthquake of August 1975 so
Butte County TWSD Annex S-5
Local Hazard Mitigation Plan Update
September 2024
damaged the ditch system that it was imperative that the District utilize the new contractual agreement.
DWR gives credit for water delivered and provides an equivalent amount of Lake Oroville water to the
District delivered through the Thermalito Power Canal.
The primary agricultural crops within the area, when the District was formed, were olive and orange
orchards, irrigated pasture, grapes and a couple of dairy operations. The District has a water right of 8,200
acre-feet from the Concow watershed and at no time shall the reservoir capacity drop below 1,000 acre-feet
to accommodate the fish population. When full, the Concow Lake has a capacity of 7,225 acre-feet.
In addition to the District’s surface water, groundwater supplies were developed from six wells located
throughout the District. Wells #1 & #6 where abandoned and a new well site was grant deeded for the
future replacement of Well #1. Although these wells have been used to supply a majority of domestic water
demands in the past, they are used as a supplemental source at present; surface water from the Concow
system provides the primary supplies. In April 2008 the District constructed a membrane filtration system
to meet state health standards and began to phase out the old pressure vessel system. It was found that the
wells would be needed to reduce the effects of disinfectant byproducts that pass through the membrane
filtration system so Wells #4 and #5 are used during the year to dilute the concentration of the production
seasons. The water supply capacity of the District was further enhanced by a 1995 decision of the State
Water Resources Control Board, which allowed TID/TWSD consumptive water use of 8,200-acre feet of
Concow Reservoir water.
S.4 Risk Assessment
As defined by FEMA, risk is a combination of hazard, vulnerability, and exposure. “It is the impact that a
hazard would have on people, services, facilities, and structures in a community and refers to the likelihood
of a hazard event resulting in an adverse condition that causes injury or damage.”
The TWSD risk assessment identifies and profiles relevant hazards and assesses the exposure of lives,
property, infrastructure, and the environment to these hazards. The process allows for a better
understanding of the District’s potential risk to hazards and provides a framework for developing and
prioritizing mitigation actions to reduce risk from future hazard events.
Building on the Community Profile above, a risk assessment was performed for the District. This includes
the following sections:
➢ S.4.1 Assets Inventory and Growth and Development Trends
➢ S.4.2 Hazard Identification
➢ S.4.3 Hazard Profiles and Vulnerability to Specific Hazards
S.4.1. Assets Inventory and Growth and Development Trends
This section provides an inventory of the TWSD’s total assets potentially at risk to hazards and an overview
of growth and development trends. This section is broken into two parts:
➢ Asset Inventory – The assets inventory identifies TWSD’s total assets, including the people and
populations; structures; critical facilities and infrastructure; community lifelines; natural, historic, and
Butte County TWSD Annex S-6
Local Hazard Mitigation Plan Update
September 2024
cultural resources; and economic assets and community activities of value. This data is not hazard
specific, but is representative of total assets within the District, potentially at risk to identified hazards
as discussed in Section S.4.3 Hazard Profiles and Vulnerability to Specific Hazards.
➢ Growth and Development Trends – A discussion of growth and development trends in the District,
both current and future, is presented.
Assets Inventory
The District’s asset inventory is detailed in the following sections:
➢ People and Populations
➢ Structures
➢ Critical Facilities and Infrastructure
➢ Community Lifelines
➢ Natural, Historic, and Cultural Resources
➢ Economic Assets and Community Activities of Value
A discussion of each of these assets follows and serves as the template for the asset discussion for each
hazard in Section S.4.3.
People and Populations
The most important asset within any community are the people and populations that reside in the
community. This section includes an inventory of past and current populations of the District and also
discusses socially vulnerable populations and underserved communities as a subsection of people and
populations located within the District and potentially at risk to hazards. Information from the District, US
Census Bureau, California Department of Finance, and other sources as detailed below form the basis of
this discussion.
The District’s service population is defined as a disadvantaged community (as defined in Title 22, Division
4, Chapter 14.5, section 64300 of the California Code of Regulations). This is based upon the service area’s
Median Household Income. The District provides payment plans to customers who experience financial
hardships.
Historic Population Trends and Current Population
The most important asset within any community are the people and populations that reside in the District.
The District provides services to approximately 12,000 residents.
Structures and Critical Facilities
This section considers the TWSD’s assets at risk, with a focus on key District assets such as critical
facilities, infrastructure, and other District assets and their values. With respect to District assets, the
majority of these assets are considered critical facilities as defined for this Plan. Critical facilities are
defined for this Plan as:
Butte County TWSD Annex S-7
Local Hazard Mitigation Plan Update
September 2024
Any facility, including without limitation, a structure, infrastructure, property,
equipment or service, that if adversely affected during a hazard event may result in
severe consequences to public health and safety or interrupt essential services and
operations for the community at any time before, during and after the hazard event.
Table S-3 lists critical facilities and other District assets identified by the District Planning Team as
important to protect in the event of a disaster. TWSD’s physical assets, valued at over $110 million, consist
of the buildings and infrastructure to support the District’s operations.
Table S-3 TWSD Critical Facilities, Infrastructure, and Other District Assets
Name of Asset Facility Type Replacement Value Which Hazards Pose
Risk
Concow Reservoir & Dam 97’ High arch cement dam $30,000,000 Flooding, Earthquakes,
Fires
Water Treatment plant Micro Membrane system $7,320,000 Power Outages,
Earthquakes, Fire
Office and maintenance yard Office and equipment storage
& repair
$1,100,000 Flooding, Earthquake
and Fires
Four deep water wells Three wells are centrifugal
1submersable
$3,000,000 Power Outages,
Earthquakes, Fire
Clearwell Storage Water Storage tank $770,000 Flooding, Earthquake
and Fires
2.5 MG Storage Water Storage Reservoir $1,500,000 Flooding, Earthquake
and Fires
59 Mile Distribution Pipe
system
2” to 30” pipe for water
Delivery
$38,940,000 Flooding, Earthquake
and Fires
34.7 Miles of sewer Collector
system
6” to 18” pipe for sewer
collection
$27,482,400 Flooding, Earthquake
and Fires
Sewer Lift Station Pump station $110,000 Power Outages,
Earthquakes, Fire
Total $110,222,400
Source: TWSD
Community Lifelines
Assessing the vulnerability of the TWSD to natural hazards and disasters also involves reviewing and
inventorying the community lifelines in place that could be affected. It is important to include these items
in hazard discussions as the continuous operation of critical government and business functions is essential
to human health and safety, property protection, and economic security. The importance of community
lifelines is discussed below:
➢ Lifelines are the most fundamental services in the community that, when stabilized, enable all other
aspects of society to function.
➢ FEMA has developed a construct for objectives-based response that prioritizes the rapid stabilization
of Community Lifelines after a disaster.
Butte County TWSD Annex S-8
Local Hazard Mitigation Plan Update
September 2024
➢ The integrated network of assets, services, and capabilities that provide lifeline services are used day -
to-day to support the recurring needs of the community and enable all other aspects of society to
function.
➢ When disrupted, decisive intervention (e.g., rapid re-establishment or employment of contingency
response solutions) is required to stabilize the incident.
Community lifelines, as defined by FEMA, include the following:
➢ Safety and Security – Law Enforcement/Security, Fire Service, Search and Rescue, Government
Service, Community Safety
➢ Food, Hydration, Shelter – Food, Water, Shelter, Agriculture
➢ Health and Medical – Medical Care, Public Health, Patient Movement, Medical Supply Chain,
Fatality Management
➢ Energy – Power Grid, Fuel
➢ Communications – Infrastructure, Responder Communications, Alerts Warnings and Messages,
Finance, 911 and Dispatch
➢ Transportation – Highway/Roadway/Motor Vehicle, Mass Transit, Railway, Aviation, Maritime
➢ Hazardous Material – Facilities, HAZMAT, Pollutants, Contaminants
➢ Water Systems – Potable Water Infrastructure, Wastewater Management
In Butte County, there is an interplay in community lifelines between all jurisdictions in the County. In
fact, most of the District’s community lifelines overlap the County’s. It should also be noted that these
lifelines collectively include many of the critical facilities and infrastructure assets inventoried for this
LHMP. Due to this fact, specific information on these community lifelines in the District and how they
may be affected by a hazard event or disaster are discussed in each hazard section; however, many of these
sections refer back to the detailed lists that are captured in the Section 4.2.1 of the Base Plan.
Natural, Historic, and Cultural Resources
Assessing the vulnerability of the District to natural hazards and disasters also involves inventorying the
natural, historic, and cultural assets of the area. This step is important for the following reasons:
➢ Environmental and natural resources add to a community’s identity and quality of life. They also help
the local economy through agriculture, tourism and recreation. They support ecosystem services, such
as clean air and water.
➢ Conserving the environment may help people mitigate risk. It can also protect sensitive habitats,
develop parks and trails, and build the economy.
➢ The community may decide that these types of resources warrant a greater degree of protection due to
their unique and irreplaceable nature and contribution to the overall economy.
➢ If these resources are impacted by a disaster, knowing so ahead of time allows for more prudent care
in the immediate aftermath, when the potential for additional impacts are higher.
➢ The rules for reconstruction, restoration, rehabilitation, and/or replacement are often different for these
types of designated resources.
➢ Natural resources can have beneficial functions that reduce the impacts of natural hazards, such as
wetlands and riparian habitat, which help absorb and attenuate floodwaters.
Butte County TWSD Annex S-9
Local Hazard Mitigation Plan Update
September 2024
Natural Resources
TWSD has a variety of natural resources of value to the District. These natural resources parallels that of
Butte County as a whole. Information can be found in Section 4.2.1 of the Base Plan.
Historic and Cultural Resources
TWSD has a variety of historic and cultural resources of value to the District. Specifically, there are
remnants of a meeting house and stone carvings from the Concow Indians near Lake Concow. These
historic and cultural resources parallels that of Butte County as a whole. Information can be found in
Section 4.2.1 of the Base Plan.
Economic Assets and Community Activities of Value
Assessing the vulnerability of the TWSD to natural hazards and disasters also involves inventorying the
economic assets and community activities of value in the District.
Economic Assets
After a disaster, economic resiliency is one of the major drivers of a speedy recovery. Each community
has specific economic drivers. Economic assets for the County were discussed in Section 4.2.1 of the Base
Plan and are assumed to be the same or similar for the District.
Community Activities of Value
Inventorying economic assets in the District and their vulnerability to natural hazards and disasters also
involves inventorying activities that have value to the community. This includes activities that are
important to a community, like long-standing traditions such as a festival or fair. Community Activities of
Value for the County were discussed in Section 4.2.1 of the Base Plan and are assumed to be the same or
similar for the District.
Growth and Development Trends
As part of the planning process, the District looked at changes in growth and development, both current and
future, and examined these changes in the context of hazard-prone areas, and how the changes in growth
and development affect loss estimates and vulnerability over time.
Population Trends and Projections
The District has no control over populations in its service territory. Growth is expected to continue.
Development since 2019 Plan
There has been significant development in Thermalito since the last LHMP update. Primary development
has been in multi-family housing. The development has not occurred in hazard prone areas. Thus, with
the exception of more people living in the area potentially exposed to natural hazards, this growth should
not cause a significant change in vulnerability of the District to identified priority hazards.
Butte County TWSD Annex S-10
Local Hazard Mitigation Plan Update
September 2024
Future Development Areas
It is important to review future development plans for the District. Future development should be sited in
areas that are away from known hazard risks. If this is not possible, mitigation should be done to ensure
that future development is protected against future hazards. The District has no control over future
development in areas the District provides water and sewer service in. Future development areas in
Thermalito are in single and multi-family residential zoned areas. They are not located in significant hazard
prone areas.
S.4.2. Hazard Identification
TWSD identified the hazards that affect the District and summarized their location, extent, likelihood of
future occurrence, potential magnitude, and significance specific to the District (see Table S-4).
Butte County TWSD Annex S-11
Local Hazard Mitigation Plan Update
September 2024
Table S-4 TWSD—Hazard Identification Assessment
Hazard
Geographic
Extent
Likelihood of
Future
Occurrences
Magnitude/
Severity Significance
Climate
Change
Influence
Climate Change Extensive Highly Likely Limited Low –
Dam Failure Extensive Occasional Catastrophic High Medium
Drought & Water shortage Extensive Likely Limited Low High
Earthquake Extensive Occasional Catastrophic Medium Low
Floods: 1%/0.5%/0.2% annual chance Occasional Likely Critical Low Medium
Floods: Localized Stormwater Significant Highly Likely Limited Low Medium
Invasive Species: Aquatic Limited Likely Limited Low Low
Invasive Species/Agricultural Hazards Extensive Highly Likely Limited Low Low
Landslide, Mudslide, and Debris Flow Significant Occasional Limited Medium Medium
Levee Failure Significant Occasional Critical Low Medium
Pandemic Extensive Occasional Critical Low Medium
Severe Weather: Extreme Heat Extensive Highly Likely Limited Low High
Severe Weather: Extreme Cold, Freeze
and Winter Storm
Extensive Highly Likely Limited Low Medium
Severe Weather: Heavy Rain and
Storms (Hail, Lightning)
Extensive Highly Likely Limited Low Medium
Severe Weather: Wind and Tornado Extensive Highly Likely Limited Low Low
Wildfire Extensive Highly Likely Catastrophic High High
Geographic Extent
Limited: Less than 10% of planning
area
Significant: 10-50% of planning area
Extensive: 50-100% of planning area
Likelihood of Future
Occurrences
Highly Likely: Near 100% chance of
occurrence in next year, or happens
every year.
Likely: Between 10 and 100% chance
of occurrence in next year, or has a
recurrence interval of 10 years or less.
Occasional: Between 1 and 10%
chance of occurrence in the next year,
or has a recurrence interval of 11 to 100
years.
Unlikely: Less than 1% chance of
occurrence in next 100 years, or has a
recurrence interval of greater than every
100 years.
Magnitude/Severity
Catastrophic: More than 50 percent of property severely damaged;
shutdown of facilities for more than 30 days; and/or multiple deaths
Critical: 25-50 percent of property severely damaged; shutdown of facilities
for at least two weeks; and/or injuries and/or illnesses result in permanent
disability
Limited: 10-25 percent of property severely damaged; shutdown of facilities
for more than a week; and/or injuries/illnesses treatable do not result in
permanent disability
Negligible: Less than 10 percent of property severely damaged, shutdown
of facilities and services for less than 24 hours; and/or injuries/illnesses
treatable with first aid
Significance
Low: Minimal potential impact
Medium: Moderate potential impact
High: Widespread potential impact
Climate Change Influence
Low: Minimal potential impact
Medium: Moderate potential impact
High: Widespread potential impact
Butte County TWSD Annex S-12
Local Hazard Mitigation Plan Update
September 2024
S.4.3. Hazard Profiles and Vulnerability to Specific Hazards
This section includes the hazard profiles and vulnerability assessment for hazards ranked of medium or
high significance specific to the District (as identified in the Significance column of Table S-4). Chapter 4
of the Base Plan provides more detailed information about these hazards and their impacts on the Butte
County Planning Area. Methodologies for evaluating vulnerabilities and calculating loss estimates are the
same as those described in Section 4.2 of the Base Plan.
Each hazard is profiled in the following format:
➢ Hazard Profile and Problem Description – A hazard profile is included for each hazard. This
includes information on:
✓ Hazard Overview - A general discussion of the hazard and related issues.
✓ Location and Extent - Location is the geographic area within the District that is affected by the
hazard. Extent is the expected range of intensity for each hazard. These are discussed in specific
detail for mapped hazards, and in more general detail for those hazards that do not have discrete
mapped hazard areas.
✓ Past Occurrences - Past occurrences are discussed for each hazard. A discussion of disaster
declarations is included in each hazard section. NCDC events are also discussed. Other past
occurrences data specific to the District follow the disaster declarations for each hazard.
✓ Climate Change—This section contains the effects of climate change (as applicable). The possible
influence of climate change on the hazard is discussed.
After the hazard profile, a vulnerability assessment is presented. As part of the vulnerability assessment,
an estimate of the vulnerability of the District to each identified hazard, in addition to the estimate of risk
of future occurrence, is provided in each of the hazard-specific sections that follow. Vulnerability is
measured in general, qualitative terms and is a summary of the potential impact based on past occurrences,
spatial extent, and damage and casualty potential. It is categorized into the following classifications:
➢ Extremely Low—The occurrence and potential cost of damage to life and property is very minimal to
nonexistent.
➢ Low—Minimal potential impact. The occurrence and potential cost of damage to life and property is
minimal.
➢ Medium—Moderate potential impact. This ranking carries a moderate threat level to the general
population and/or built environment. Here the potential damage is more isolated and less costly than a
more widespread disaster.
➢ High—Widespread potential impact. This ranking carries a high threat to the general population and/or
built environment. The potential for damage is widespread. Hazards in this category may have
occurred in the past.
➢ Extremely High—Very widespread with catastrophic impact.
After this classification, a general discussion of hazard vulnerabilities occurs. This is done in the following
format:
➢ Local Concerns – The includes District provided information on how the District is uniquely affected
by or vulnerable to each hazard.
Butte County TWSD Annex S-13
Local Hazard Mitigation Plan Update
September 2024
➢ Assets at Risk – A discussion of the assets at risk follows, presented in the same format as in Section
S.4.1 above. This includes sections on: People and Populations; Structures; Critical Facilities and
Infrastructure, Community Lifelines; Natural, Historic, and Cultural Resources; and Economic Assets
and Community Activities of Value. These are discussed in specific terms for mapped hazards, and in
more general terms for those hazards that are unmapped.
➢ Impacts – A discussion on hazard impacts follows. Impacts describe how each hazard can affect the
District and their assets. The type and severity of impacts reflect both the potential magnitude of the
hazard and the vulnerability of the asset. Impacts are also affected by the community’s ability to
mitigate, prepare for, respond to, and recover from an event.
➢ Future Development – A discussion of how future development will be affected by the hazard is also
included. This is addressed specifically for mapped hazards, and in more general terms for those
hazards that are unmapped.
Power Interruption/Power Failure: A Common Vulnerability of all Hazards
An impact of almost all hazards evaluated as part of this LHMP Update relates to power shortage and/or
power failures. The US power grid crisscrosses the country, bringing electricity to homes, offices, factories,
warehouses, farms, traffic lights and even campgrounds. According to statistics gathered by the U.S.
Department of Energy, major blackouts are on the upswing. Incredibly, over the past two decades,
blackouts impacting at least 50,000 customers have increased 124 percent. The electric power industry
does not have a universal agreement for classifying disruptions. Nevertheless, it is important to recognize
that different types of outages are possible so that plans may be made to handle them effectively. In addition
to blackouts, brownouts can occur. A brownout is an intentional or unintentional drop in voltage in an
electrical power supply system. Intentional brownouts are used for load reduction in an emergency.
Electric power disruptions can be generally grouped into two categories: intentional and unintentional.
More information on types of power disruptions can be found in Section 4.3 of the Base Plan.
Public Safety Power Shutoff (PSPS)
A new intentional disruption type of power shortage/failure event has recently occurred in California. In
recent years, several wildfires have started as a result of downed power lines or electrical equipment. This
was the case for the Camp Fire in 2018. As a result, California’s three largest energy companies (including
PG&E), at the direction of the California Public Utilities Commission (CPUC), are coordinating to prepare
all Californians for the threat of wildfires and power outages during times of e xtreme (fire) weather. To
help protect customers and communities during extreme fire weather events, electric power may be shut
off for public safety in an effort to prevent wildfire. This is called a PSPS. More information on PSPS
criteria can be found in Section 4.3 of the Base Plan.
Enhanced Powerline Safety Settings (EPSS)
In addition to PSPSs, to help prevent wildfires, electric utilities have begun to evolve safety efforts. This
includes installing safety settings on powerlines in and around high fire-risk areas. These are known as
Enhanced Powerline Safety Settings (EPSS), and they help prevent falling tree branches, animals and other
hazards from starting a wildfire. By stopping ignitions, it helps prevent wildfires from starting and
spreading. According to PG&E, if ignitions occur, the size of fires are much smaller due to EPSS. In 2022,
Butte County TWSD Annex S-14
Local Hazard Mitigation Plan Update
September 2024
there was a 99% decrease in acres impacted by ignitions (as measured by fire size from electric distribution
equipment (compared to the 2018-2020 average). This decrease occurred despite dry conditions.
Local Concerns
The District is highly sensitive to public safety power shutoffs. Emergency generators are in place for the
occurrence, but extended power shut offs can pose a significant issue. Previous PSPS events have resulted
in the District to procuring several diesel fuel deliveries to maintain the emergency generators.
Dam Failure
Likelihood of Future Occurrence–Occasional
Vulnerability–High
Hazard Profile and Problem Description
Dams are manmade structures built for a variety of uses including flood protection, power generation,
agriculture, water supply, and recreation. When dams are constructed for flood protection, they are usually
engineered to withstand a flood with a computed risk of occurrence. For example, a dam may be designed
to contain a flood at a location on a stream that has a certain probability of occurring in any given year. If
prolonged periods of rainfall and flooding occur that exceed the design requirements, that structure may be
overtopped or fail. Overtopping is the primary cause of earthen dam failure in the United States.
Dam failure is a natural disaster from two perspectives. First, the inundation from released waters resulting
from dam failure is related to naturally occurring floodwaters. Second, a total dam failure would most
probably happen as a consequence of the natural disaster triggering the event, such as an earthquake.
Location and Extent
An inventory map of dams located within Butte County was shown in Section 4.3.7 in the Base Plan. Dams
with an inundation area within the TWSD are shown on Figure S-2. This includes five extremely high
hazard dams – Lake Almanor, Oroville, Paradise, Rock Creek, and Thermalito Afterbay. It also includes
twelve high hazard dams – Bidwell Bar Canyon Saddle, Bucks Diversion, Bucks Storage, Butte Valley,
Cresta, Lake Wyandotte, Magala, Miners Ranch, Philbrook, Shasta, Thermalito Diversion, Thermalito
Forebay, and one significant hazard dam – Lower Three Lakes. There is no scale with which to measure
dam failure. However, FEMA and CA DWR Division of Safety of Dams (DSOD) assigns hazard potential
classifications to dams within the State that provides information on the potential impact should a dam fail.
The following two factors are considered when assigning hazard ratings: existing land use and land use
controls (zoning) downstream of the dam. FEMA categorizes the downstream hazard potential into three
categories in increasing severity: Low, Significant, and High. DSOD adds a fourth category of Extremely
High. Dams are classified in these four categories that identify the potential hazard to life and property.
These were discussed in more detail in Section 4.3.7 of the Base Plan.
While a dam may fill slowly with runoff from winter storms, a dam break has a very quick speed of onset.
The duration of dam failure is generally not long – only as long as it takes to empty the reservoir of water
the dam held back. For dam overtopping, the speed of onset is somewhat slower than that of a dam break,
Butte County TWSD Annex S-15
Local Hazard Mitigation Plan Update
September 2024
and the duration is longer (as evidenced in the 2017 Oroville Dam spillway event). The District would be
affected for as long as the flood waters from the dam failure took to drain downstream.
Geographic flood extent from the DSOD and Cal OES dam inundation areas is shown on Figure S-2 and
Figure S-3.
Butte County TWSD Annex S-16
Local Hazard Mitigation Plan Update
September 2024
Figure S-2 TWSD – Extremely High Hazard Dam Inundation Areas
Butte County TWSD Annex S-17
Local Hazard Mitigation Plan Update
September 2024
Figure S-3 TWSD – High Hazard Dam Inundation Areas
Butte County TWSD Annex S-18
Local Hazard Mitigation Plan Update
September 2024
Figure S-4 Significant Hazard Dam Inundation Areas
Butte County TWSD Annex S-19
Local Hazard Mitigation Plan Update
September 2024
Past Occurrences
Disaster Declaration History
There has been one state and one federal disaster declarations for dam failure in the County from the 2017
Oroville Spillway incident.
Table S-5 Butte County – State and Federal Disaster Declarations from Dam Failure 1950-
2024
Disaster Type Federal Declarations State Declarations
Count Years Count Years
Flood (from dam failure) 1 2017 1 2017
Source: CAL OES, FEMA
NCDC Events
There have been no NCDC dam failure events in Butte County. An event of flooding was reported that
threatened Oroville Dam on 2/12/2017. This flooding was related to the Oroville spillway event.
TWSD Events
The District noted no past dam events that have impacted or affected the area.
Climate Change and Dam Failure
It is likely that climate change will increase the chance of future occurrence as well as future impacts
associated with dam failure. More information on future impacts to the District can be found in the Future
Conditions/Future Development section of the Vulnerability Assessment below.
The 2023 California State Hazard Mitigation Plan noted that Modeling described in California’s Fourth
Climate Change Assessment projects less frequent but more extreme daily precipitation. Year -to-year
precipitation will become more volatile, and the number of dry years will increase by mid-century. As the
climate continues to warm, atmospheric rivers will carry more moisture, and extreme precipitation may
increase. Climate model projections show a tendency for the northern part of the State to become wetter.
Increases in both precipitation and heat causing snow melt in areas upstream of dams could increase the
potential for dam failure and uncontrolled releases in Butte County and the District.
Vulnerability to Dam Failure
The vulnerability of the District to dam failure flooding would vary depending on which dam fails and the
nature and extent of the dam failure and associated flooding. An assessment of a community’s vulnerability
to dam failure begins with an understanding of local exposure to dam failure. This is included in the Local
Concerns section below followed by a discussion of the District’s Assets at Risk to this hazard.
Butte County TWSD Annex S-20
Local Hazard Mitigation Plan Update
September 2024
Local Concerns
The District has specific concerns and unique vulnerabilities regarding this hazard. These concerns form a
portion of the basis for the mitigation strategy and mitigation actions that seek to reduce vulnerabilities to
this hazard.
The District does own and maintains the Concow dam and reservoir. This is a high Hazard dam, meaning
property and at least one person downstream would be at risk should the dam overtop or fail. Impacts to
the TWSD from dam failure include damage to property and critical facilities, as well as potential loss of
life. Other impacts include the costs to TWSD to rebuild the Concow dam if it failed. The District would
lose its ability to store/convey surface water per its DWR contract. A potential mitigation action would be
to assess the vulnerability of the dam structurally. Once concerns are identified, rehabilitation efforts could
take place.
Mitigation efforts will focus on maintaining the dam as well as the area surrounding it. Along with this,
it’s important that the shoreline is cleared of debris and invasive plant species. The condition of the dam is
inspected regularly by District staff and annually by the Division of Safety of Dams.
Assets at Risk
Assets at risk from dam include people and populations served; structures and critical facilities; community
lifelines; natural, historic, and cultural resources; economic assets; and community activities of value.
These are discussed in the following sections.
People and Populations Served
All people and populations located in dam inundation areas are vulnerable to dam failure. Certain
vulnerable populations may be at increased risk to dam failure, especially during a large event with minimal
advance notice. These vulnerable populations may include: the unsheltered, those with limited mobility,
and those that lack the resources to leave the area. District residents that live in these dam inundation areas
are often the most vulnerable. Not only are the residents at risk, but their homes and contents are all at risk,
compounding the impacts associated with significant hazard events. The failure of the Oroville Dam would
impact all resident equally.
Structures and Critical Facilities
Most structures and critical facilities in the District have some measure of risk to dam failure. Dam failure
flooding can affect the built environment of the District. Structures in dam inundation areas are at risk and
depending on flood depths, can range from slight damage to totally inundated. The structure the District is
worried about is the Concow Dam and Reservoir.
Community Lifelines
Dam failure flooding presents a threat to life and property, including community lifelines in the District. A
catastrophic dam failure could overwhelm local response capabilities and require evacuations to save lives.
Butte County TWSD Annex S-21
Local Hazard Mitigation Plan Update
September 2024
Many of the District’s community lifelines are the same as or similar to Butte County’s. This was discussed
in greater detail in Section 4.3.7 of the Base Plan.
Natural, Historic, and Cultural Resources
A major dam failure event and associated flooding could have a devastating impact on the District. Large
flood events can affect all natural, historic, and cultural resources that lie in the dam inundation areas. There
are a number of ways floodwaters associated with a dam failure event can impact natural resources and the
environment: Wildlife habitats can be destroyed by floodwaters. Contaminated floodwater can pollute
rivers and habitats. Silt and sediment can destroy natural areas. Riverbanks and natural levées can be
eliminated as rivers reach bankfull capacity. Rivers can be widened, and deposition can increase
downstream. Trees can be uprooted by high-velocity water flow. Plants that survive the initial flood may
die due to being inundated with water. Historic and cultural resources may also be affected. Generally, the
impacts are associated with damage to these structures within the inundated areas, but other cultural
resources such as those associated with Native Americans and old tribal areas can also be disturbed,
damaged, and lost during dam failure flood events.
Economic Assets and Community Activities of Value
Economic assets and community activities of value for the District are similar or the same as those for the
County as a whole. Those assets and activities were discussed in greater detail in Section 4.3.7 of the Base
Plan.
Impacts from Dam Failure
Impacts to the District from dam failure flooding could be extensive and widespread and include loss of
life and injury, flooding and damage to property and structures, damage to critical facilities and
infrastructure, loss of natural resources, and all other flood related impacts. Levees within the District and
surrounding areas may also be damaged or destroyed contributing to the flood waters. Additionally, mass
evacuations may be necessary and compounded by impacts to transportation systems and infrastructure.
Economic losses to the District and Butte County Planning Area can also be significant.
Other impacts associated with dam failure are landslides, bank erosion, and destruction of habitat. Dam
failures can cause downstream flooding and can transport large volumes of sediment and debris and
contaminants from the floodwaters. Other environmental impacts can include contamination from septic
system failures and releases of contaminants from hazardous materials facilities, contamination of potable
water supplies; changes in configurations of streams; loss of wildlife habitats; and degradation of wetlands.
A large dam failure event could have significant and catastrophic impacts.
Impacts to identified assets at risk to this hazard and the overall vulnerability of the District may be affected
in the future by climate change. It is likely that climate change will increase the chance of future occurrence
as well as future impacts associated with dam failure. Changes in population patterns (migration, density,
or the makeup of socially vulnerable populations) and changes in land use and development, and the extent
to which they affect this hazard, are discussed in the Future Conditions/Future Development discussion
below.
Butte County TWSD Annex S-22
Local Hazard Mitigation Plan Update
September 2024
Future Conditions/Future Development
Future conditions may be affected by climate change, changes in population patterns (migration, density,
or the makeup of socially vulnerable populations), and changes in land use and development. Findings on
this for the District include the following:
➢ As discussed in the hazard profile section, climate change is anticipated to exacerbate this hazard over
time.
➢ While population projections for the area served by the District show additional expected growth, these
anticipated future changes in population are expected to be relatively small, which limits additional
impacts to the District. Additional growth within the dam inundation areas of the District would place
additional populations at risk to dam failure. The District noted it has no control over population
changes, it merely reacts to them by providing additional (or reduced) services.
➢ Land use planning should be proactive to address future hazard conditions. Locating new development,
structures, and critical facilities and infrastructure within or near areas of dam failure risk may put
additional development at risk. However, County and Town building codes are in effect to partially
reduce this risk and should be updated as necessary to continue to address future dam failure conditions.
Thus, depending on the location of new development and adherence to protective building codes,
changes in land use and development may or may not increase the impacts and associated
vulnerabilities of the District to this hazard.
Future dam failures events may occur in the District. Given the high number of affected parcels and
structures, future development in the District could be affected by dam failures and associated flooding.
Siting of future development areas should take dam failure flooding into account. Future development
would include preventative maintenance and any upgrades necessary to maintain the integrity of Concow
Dam.
Earthquake
Likelihood of Future Occurrence–Occasional
Vulnerability–Medium
Hazard Profile and Problem Description
An earthquake is caused by a sudden slip on a fault. Stresses in the earth’s outer layer push the sides of the
fault together. Stress builds up, and the rocks slip suddenly, releasing energy in waves that travel through
the earth’s crust and cause the shaking that is felt during an earthquake. Earthquakes can cause structural
damage, injury, and loss of life, as well as damage to infrastructure networks, such as water, power, gas,
communication, and transportation. Earthquakes may also cause collateral emergencies including dam and
levee failures, seiches, hazmat incidents, fires, avalanches, and landslides. The degree of damage depends
on many interrelated factors. Among these are: the magnitude, focal depth, distance from the causative
fault, source mechanism, duration of shaking, high rock accelerations, type of surface deposits or bedrock,
degree of consolidation of surface deposits, presence of high groundwater, topography, and the design,
type, and quality of building construction.
The District is highly concerned about earthquakes and earthquake liquefaction.
Butte County TWSD Annex S-23
Local Hazard Mitigation Plan Update
September 2024
Location and Extent
Surface Fault and Ground Shaking
Since earthquakes are regional events, the whole of the District is at risk to earthquake. The District, Butte
County, and surrounding areas have some measure of risk from significant seismic and geologic hazards.
Faults in and around the District were shown in Section 4.3.9 of the Base Plan. A significant seismic event
on any of these major faults could cause serious damage in the District.
The amount of energy released during an earthquake is usually expressed as a magnitude and is measured
directly from the earthquake as recorded on seismographs. An earthquake’s magnitude is expressed in
whole numbers and decimals (e.g., 6.8). Seismologists have developed several magnitude scales, as
discussed in Section 4.3.9 of the Base Plan.
Another measure of earthquake severity is intensity. Intensity is an expression of the amount of shaking at
any given location on the ground surface. Seismic shaking is typically the greatest cause of losses to
structures during earthquakes. The District is located in an area where earthquakes of significant magnitude
occur, so both magnitude and intensity of earthquakes are expected to remain moderate. Seismic shaking
maps for the area in Section 4.3.9 of the Base Plan show Butte County and the District fall within a low to
moderate shake risk.
Earthquake-Induced Liquefaction
When ground liquefies in an earthquake, it behaves like a liquid and may sink, spread, or erupt in sand
boils. This can cause pipes to break, roads and sidewalks to buckle, and building foundations to be
damaged. Liquefaction can only occur under certain circumstances. Soil that is loose, sandy, silty, or
saturated with water can result in soil liquefaction if it is shaken intensely for an extended period. More
details on soils and liquefaction follows:
➢ Loose Soils – The soil must be loose, such as uncompacted or unconsolidated sand and silt without
much clay. This happens most often near creeks or waterways, on dry creek beds, and areas of man-
made fill.
➢ Soggy Soils – The sand and silt must be soggy and saturated with water due to a high water table.
➢ Ground Shaking – The ground must be shaken long and hard enough by the earthquake to trigger
liquefaction.
Liquefaction accompanies an earthquake, so the speed of onset is short. Duration is similar to the length
of the earthquake shake. There are mapped areas of areas susceptible to earthquake-induced liquefaction
in the District from the USGS/CGS. These areas are shown on Figure S-5. Liquefaction hazard maps
express where the ground is susceptible to liquefaction, and where the ground is likely to be shaken long
and intensely in an earthquake.
Butte County TWSD Annex S-24
Local Hazard Mitigation Plan Update
September 2024
Figure S-5 TWSD – Earthquake Liquefaction Susceptibility Zones
Butte County TWSD Annex S-25
Local Hazard Mitigation Plan Update
September 2024
Past Occurrences
Disaster Declaration History
The District noted that there has been no state and 1 federal disaster declaration from the 1975 Oroville
earthquake, as shown in Table S-6.
Table S-6 Butte County Disaster Declarations from Earthquake 1950-2024
Disaster Type Federal Declarations State Declarations
Count Years Count Years
Earthquake 1 1975 0
Source: Cal OES, FEMA
NCDC Events
The NCDC does not track earthquake events.
TWSD Events
As shown in the Base Plan, only the 1975 federal disaster declaration has occurred in the County due to
Oroville earthquake. The District experienced several water and sewer pipeline failures due to the
earthquake. The treatment plant structures also experienced some structural issues. The HMPC noted no
other past occurrences of earthquakes or liquefaction that affected the District in any meaningful way.
Climate Change and Earthquake
Climate change is unlikely to increase earthquake frequency or strength.
Vulnerability to Earthquake
The combination of plate tectonics and associated California coastal mountain range building geology
generates earthquakes as a result of the periodic release of tectonic stresses Earthquake vulnerability is
primarily based on population and the built environment. Urban areas in high seismic hazard zones are the
most vulnerable, while uninhabited and more rural areas are less vulnerable. The primary impacts of
concern are life safety and property damage. Although several faults are located in and near the District
and Butte County Planning Area, seismic hazard mapping indicates that the Planning Area has low to
moderate seismic hazard potential. However, there is potential that the District and the Butte County
Planning Area will be subject to some moderate to severe seismic shaking in future events. Some degree
of structural damage due to stronger seismic shaking should be expected in earthquakes occurring with and
epicenter near the District.
Earthquake shaking can cause liquefaction to occur in the District. Areas with loose soil and high water
tables are at risk from liquefaction. There are several areas in and near the District prone to liquefaction.
Butte County TWSD Annex S-26
Local Hazard Mitigation Plan Update
September 2024
The whole of the District is at some measure of vulnerability to earthquake. An assessment of a
community’s vulnerability to earthquakes begins with an understanding of local exposure to earthquakes.
This is included in the Local Concerns section below. After that section, assets at risk are discussed.
Local Concerns
The District has specific concerns and unique vulnerabilities regarding this hazard. These concerns form a
portion of the basis for the mitigation strategy and mitigation actions that seek to reduce vulnerabilities to
this hazard.
The Uniform Building Code (UBC) identifies four seismic zones in the United States. The zones are
numbered one through four, with Zone 4 representing the highest level of seismic hazard. The UBC
establishes more stringent construction standards for areas within Zones 3 and 4. All of California lies
within either Zone 3 or Zone 4. The TWSD is within Zone 3.
Impacts to the District included damage to facilities and distribution lines. Concow Dam could also be
impacted. District sewer infrastructure including lift stations, collection lines and manholes could also be
damaged during an earthquake. A proposed mitigation action would be to replace all of the vulnerable
infrastructure such as old steel mains.
Assets at Risk
Many assets in the District are at risk to ground shaking (including liquefaction). Assets at risk from
earthquake include people and populations served; structures and critical facilities; community lifelines;
natural, historic, and cultural resources; economic assets; and community activities of value. These are
discussed in the following sections.
People and Populations Served
All people and populations are at risk from earthquake shaking and surface fault. Those at heightened risk
include:
➢ The unsheltered
➢ Infants and children under age five and their caregivers
➢ Elderly (65 and older)
➢ Individuals with disabilities
➢ Individuals dependent on medical equipment
➢ Individuals with impaired mobility
The greatest risk to people and populations from earthquake is death and injury. More information on
people and populations at risk to earthquake shaking events can be seen in the Hazus scenarios developed
for this LHMP. More information on the Hazus scenarios and how the Butte County Planning Area is
affected is included in Section 4.3.9 of the Base Plan. Information on populations at risk to liquefaction is
detailed below.
Butte County TWSD Annex S-27
Local Hazard Mitigation Plan Update
September 2024
Structures and Critical Facilities
All structures in the District are vulnerable to earthquakes, depending on the severity and location of the
shake. Unreinforced masonry (URM) is at a much greater risk to earthquakes. There are no URM or soft
story buildings in the District. The District has specific facility concerns with earthquake this includes those
facilities shown on Table S-7.
Table S-7 TWSD – Facilities at Risk from Earthquake
Name of Asset Facility Type Replacement Value
Concow Reservoir & Dam 97’ High arch cement dam $30,000,000
Water Treatment plant Micro Membrane system $7,320,000
Office and maintenance yard Office and equipment storage & repair $1,100,000
Four deep water wells Three wells are centrifugal
1submersable
$3,000,000
Clearwell Storage Water Storage tank $770,000
2.5 MG Storage Water Storage Reservoir $1,500,000
59 Mile Distribution Pipe system 2” to 30” pipe for water Delivery $38,940,000
34.7 Miles of sewer Collector system 6” to 18” pipe for sewer collection $27,482,400
Sewer Lift Station Pump station $110,000
Total $110,222,400
Source: TWSD
Earthquake and its related hazards (like liquefaction) are a concern to the District. Earthquakes can damage
critical facilities and infrastructure that provide vital services to the District. The critical facilities at risk to
earthquake are presented in the Hazus analysis in Section 4.3.9 of the Base Plan.
Community Lifelines
All community lifelines in the District are vulnerable to earthquakes, depending on the severity and location
of the shake. A major earthquake event could cause these lifelines to be overwhelmed. Some of these
would be able to be restored to service quickly, while others would take more time having a prolonged
impact on the people and structures within the District. More information on lifelines at risk can be seen
in the Hazus scenarios in Section 4.3.9 of the Base Plan.
Natural, Historic, and Cultural Resources
The 2023 State Hazard Mitigation Plan noted that environmental problems from earthquakes can be
numerous. It is possible for earthquakes to reroute streams, which can change the water quality, possibly
damaging habitat and feeding areas. Streams fed by groundwater and/or springs may dry up because of
changes in underlying geology. Another threat to the environment from earthquakes is the potential release
of hazardous materials. Historical and cultural resources are at risk, often due to their age and construction
types. The Hazus scenarios in Section 4.3.9 of the Base Plan and included below are relatively silent on
the vulnerability to natural, historic, and cultural resources, but impacts to these resources could be long
lasting.
Butte County TWSD Annex S-28
Local Hazard Mitigation Plan Update
September 2024
Any natural, historic, or cultural resource that is in the earthquake liquefaction zone would be at potential
risk. For the natural resources, this is likely to be limited. Historic and cultural resources that are structures
or housed in structures could be vulnerable to liquefaction. It is more likely that earthquake would have a
much greater effect than the follow-on liquefaction.
Economic Assets and Community Activities of Value
Economic assets and community activities of value for the District are similar or the same as those for the
County as a whole. Those assets and activities were discussed in greater detail in the Hazus scenarios in
Section 4.3.9 of the Base Plan.
Impacts from Earthquake (and liquefaction)
Earthquakes can strike without warning and cause dramatic changes to the landscape of an area that can
have devastating impacts on the built environment. The greatest impact is to life safety of TWSD residents
and visitors. Other impacts to the District would include damages to infrastructure such as roads, bridges,
and dams; damages and loss of services to utilities and critical infrastructure, including those related to gas,
power, water, wastewater and communication systems; damages to structures and other development; and
possible loss of life and injuries.
Earthquakes can also cause failure of dams, levees, and reservoirs. Facilities and land downslope from
dams or water reservoirs or behind levees might be subject to flooding, if the dams, reservoirs, or levees
fail as a result of an earthquake.
Ground settlement during liquefaction can cause damage when the amount of settlement varies significantly
across the length of a structure. Liquefaction can occur in susceptible soils below bodies of water and can
severely damage bridges, wharves, piers, and other structures at ports and harbors, as well as underwater
utility lines.
Impacts that are not quantified, but can be anticipated in large future events, include:
➢ Injury and loss of life;
➢ Commercial and residential structural and property damage;
➢ Disruption of and damage to public infrastructure, utilities, and services;
➢ Damage to roads/bridges resulting in loss of mobility;
➢ Significant economic impact (jobs, sales, tax revenue) to the community; and
➢ Negative impact on commercial and residential property values
Impacts to identified assets at risk to this hazard and the overall vulnerability of the District may be affected
in the future by climate change. Climate change is not thought to affect future impacts associated with
earthquake. Changes in population patterns (migration, density, or the makeup of socially vulnerable
populations) and changes in land use and development, and the extent to which they affect this hazard, are
discussed in the Future Conditions/Future Development discussion below.
Butte County TWSD Annex S-29
Local Hazard Mitigation Plan Update
September 2024
Future Conditions/Future Development
Future conditions may be affected by climate change, changes in population patterns (migration, density,
or the makeup of socially vulnerable populations), and changes in land use and development. Findings on
this for the District include the following:
➢ As discussed in the hazard profile section, climate change is not anticipated to affect this hazard over
time.
➢ While population projections for the area served by the District show additional expected growth, these
anticipated future changes in population are expected to be relatively small, which limits additional
impacts to the District. Vulnerable population groups could face disproportionate effects from an
earthquake and should be planned for. The District noted it has no control over population changes, it
merely reacts to them by providing additional (or reduced) services.
➢ Any changes in land use and development will affect the earthquake risk in the District, as additional
buildings equate to additional risk. Building codes are in effect to reduce this risk and should be updated
as necessary to continue to address future earthquake conditions. With adherence to development
standards, future losses to new development should be minimal.
Although new growth and development corridors would fall in the area affected by earthquake, given the
small chance of major earthquake and the building codes in effect, development in areas prone to
earthquakes will continue to occur. The District enforces the state building code, which mandates
construction techniques that minimize seismic hazards. All District building construction and pipeline
installation will be to the current California Seismic Code.
Landslide, Mudslide, and Debris Flow
Likelihood of Future Occurrence–Likely
Vulnerability–Medium
Hazard Profile and Problem Description
Like its earthquake‐generating faults, California’s mountainous terrain is a consequence of dynamic
geologic processes in operation as the North American Plate grinds past the Pacific Plate. According to the
CGS, a landslide is a general term for a variety of mass-movement processes that generate a down-slope
movement of mud, soil, rock, and/or vegetation. Landslides are classified into many different types based
on form and type of movement. They range from slow‐moving rotational slumps and earth flows, which
can slowly distress structures but are less threatening to personal safety, to fast‐moving rock avalanches
and debris flows that are a serious threat to structures and have been responsible for most fatalities during
landslide events. For the purposes of this LHMP Update, the term landslide includes mudslides, debris
flows, and rockfalls that tend to occur suddenly; as well as hillside erosion, which is a similar process that
tends to occur on smaller scales and more gradually but can exacerbate landslide events.
Landslides, debris flows and mudslides are closely related to flooding, as both processes are related to
precipitation, runoff, and the saturation of ground by water. In addition, landslides, mud flows, and debris
flows can occur on small, steep stream channels and are often mistaken for floods. However, landslide
Butte County TWSD Annex S-30
Local Hazard Mitigation Plan Update
September 2024
events may be much more destructive than floods because of their higher densities, high debris loads, and
high velocities.
Soil erosion is another common form of soil instability. Erosion is a function of soil type, slope, rainfall
intensity, and groundcover. It accounts for a loss in many dollars of valuable soil, is aesthetically
displeasing, and often induces even greater rates of erosion and sedimentation. Sedimentation is simply
the accumulation of soil as a result of erosion. Construction activities often contribute greatly to erosion
and sedimentation. Besides being a pollutant in its own right, sediment acts as a transport medium for other
pollutants, especially nutrients, pesticides, and heavy metals, which adhere to the eroded soil particles. As
the sediment drains into watercourses, the combination of these pollutants adversely affects water quality.
Natural conditions that contribute to landslide, mudslides, debris flows, hillside and streambank erosion,
include the following:
➢ Degree of slope
➢ Water (heavy rain, river flows, or wave action)
➢ Unconsolidated soil or soft rock and sediments
➢ Lack of vegetation (no stabilizing root structure)
➢ Previous wildfires and other forest disturbances (discussed in the Wildfire section below)
➢ Road building, excavation, and grading
➢ Earthquake
The 2023 California State Hazard Mitigation Plan noted that more than one third of California is
mountainous terrain that generally trends parallel to the coast, forming a barrier that captures moisture from
offshore storms originating in the Gulf of Alaska and Mexico. Steep topography, weak rocks, heavy winter
rains, and occasional earthquakes all lead to slope failures more frequently than would otherwise occur
under gravity alone. This is true in the sloped areas in the District.
Location and Extent
Landslides can be expected in areas with steep slopes and weak soils. It can also occur in areas where
erosion has previously occurred. Both winter storms (precipitation-induced) and earthquake triggered
landslides tend to occur in or near places that have experienced previous landslides. However, landslides
may also occur in other locations over time.
Figure S-6 shows the CGS areas at susceptible to deep-seated landslides. The legend on Figure S-6 shows
the susceptibility scale (from 0-X with 0 being the least and X being the most susceptible) that the CGS
uses to show the susceptibility of landslides. It is a primarily a combination of slope class and rock strength.
According to the 2023 State Hazard Mitigation Plan, the susceptibility classes were further categorized into
Very High (susceptibility class X) and High (susceptibility classes VII, VIII, & IX) for exposure analysis.
The rest of the classes were not categorized. CGS mapping indicates that the eastern portions of the District
and surrounding area are at high to very high susceptibility areas for landslides. This can be seen in the
darker orange and red colors. The speed of onset of landslide is often short, especially in post-wildfire burn
scar areas, but it can also take years for a slope to fail. Landslide duration is usually short, though digging
out and repairing landslide areas can take some time.
Butte County TWSD Annex S-31
Local Hazard Mitigation Plan Update
September 2024
Figure S-6 TWSD – Susceptibility to Deep-Seated Landslides
Butte County TWSD Annex S-32
Local Hazard Mitigation Plan Update
September 2024
Past Occurrences
Disaster Declarations
There have been no federal or state disaster declarations from landslide.
NCDC Events
The NCDC contains no direct records for landslides in Butte County. It does however, contain a heavy rain
event on January 9, 2017 caused a rock/mud slide covered the northbound lane of Highway 162 near the
intersection with Simmons Rd. on the east side of Lake Oroville.
TWSD Past Occurrences
The District noted no landslide, mudslide, or debris flow events that have affected the area serviced.
Climate Change and Landslide and Debris Flows
It is likely that climate change will increase the chance of future occurrence as well as future impacts
associated with landslide and debris flow. More information on future impacts to the District can be found
in the Future Conditions/Future Development section of the Vulnerability Assessment below.
According to the 2021 CAS, climate change may result in precipitation extremes (i.e., wetter wet periods
and drier dry periods). More information on precipitation increases can be found in the Severe Weather:
Heavy Rain and Storms. While total average annual rainfall may decrease only slightly, rainfall is predicted
to occur in fewer, more intense precipitation events. The combination of a generally drier climate in the
future, which will increase the chance of drought and wildfires, and the occasional extreme downpour is
likely to cause more mudslides, landslides, and debris flows.
Vulnerability from Landslide
Portions of the District are at some measure of vulnerability to landslide. An assessment of a community’s
vulnerability to landslide begins with an understanding of local exposure to landslide. This is included in
the Local Concerns section below followed by a discussion of the District’s Assets at Risk to this hazard.
Local Concerns
The District has specific concerns and unique vulnerabilities regarding this hazard. These concerns form a
portion of the basis for the mitigation strategy and mitigation actions that seek to reduce vulnerabilities to
this hazard.
The District has contended with sediment intrusion into the inlets of Concow Reservoir for some time.
Sediment deposition increased significantly following the Camp Fire. Approximately 80% of the reservoirs
watershed burned. The mitigation project for this hazard would consist of removing the deposited sediment
and creating a barrier for future sedimentation.
Butte County TWSD Annex S-33
Local Hazard Mitigation Plan Update
September 2024
Assets at Risk
Assets at risk from landslide include people and populations served; structures and critical facilities;
community lifelines; natural, historic, and cultural resources; economic assets; and community activities of
value. These are discussed in the following sections.
People and Populations Served
All populations located within areas of landslide susceptibility, especially in the High to Very High hazard
areas (i.e., Classes VII to X) are at some vulnerability to landslide. This includes those people residing in
these landslide potential areas as well as those that might reside or work within the landslide run out areas.
People residing in these areas may also be cut off from transportation routes if roads and streets providing
a means of ingress and egress are impacted. Certain vulnerable populations may be at greater risk due to
the often sudden onset of a landslide event and include: the unsheltered, those with limited mobility, and
those that lack the resources to leave the area.
District residents that live in the High and Very High landslide susceptibility areas are often the most
vulnerable, but those who live in in the landslide run out areas (which are not mapped) are also vulnerable.
Not only are the residents at risk, but their homes and contents are all at risk, compounding the impacts
associated with significant hazard events.
Structures
Landslides can affect the built environment of the District and those structures and critical facilities located
within the High to Very High hazard areas (i.e., Classes VII to X) are especially vulnerable, as are the
structures located within the landslide run out areas. The District noted no District-owned facilities in these
areas.
Community Lifelines
Community lifelines may be affected by landslide. Landslide is unlikely to overwhelm community
lifelines. Many of the District’s community lifelines are the same as or similar to Butte County’s. This
was discussed in greater detail in Section 4.3.14 of the Base Plan
Natural, Historic, and Cultural Resources
Landslides can affect natural, historic, and cultural resources that lie in the landslide area, or the landslide
run out area. Landslides can destroy large tracts of forest and open space areas, destroy wildlife habitat,
and remove productive soils and vegetation from slopes. It can also fill in waterways, impact water quality,
and potentially affect flooding potential. Natural resources that fall in the High or Very High susceptibility
areas shown on Figure S-6 would be most vulnerable, as well as those in the run out areas.
Butte County TWSD Annex S-34
Local Hazard Mitigation Plan Update
September 2024
Economic Assets and Community Activities of Value
Economic assets and community activities of value for the District are similar or the same as those for the
County as a whole. Those assets and activities were discussed in greater detail in Section 4.3.14 of the
Base Plan.
Impacts from Landslide
Any type of landslide may result in damages or complete destruction of buildings in their path, as well as
deaths and injuries. Landslides can cause road blockages by depositing debris on road surfaces or road
damage if the road surface itself slides downhill. Utility lines and pipes are also prone to breakage in slide
areas. Large landslides can collapse into water bodies, causing seiches. Landslides can relocate river
channels. Landslides and debris flows can also impact water quality and the storage capacity of surface
water reservoirs used to store potable water.
Landslides, debris flows, and mud flows impacts vary by location and severity of any given event and will
likely only affect certain areas of the District susceptible to landslide. Based on the risk assessment, there
is limited potential for significant landslides to occur in the District. Most, but not all, of the historic
landslides in the District have been minor, localized events that are more of a nuisance than a disaster.
Impacts that are not quantified, but can be anticipated in large future events, include:
➢ Injury and loss of life;
➢ Commercial and residential structural and property damage;
➢ Disruption of and damage to public infrastructure, utilities, and services;
➢ Damage to roads/bridges resulting in loss of mobility;
➢ Significant economic impact (jobs, sales, tax revenue) to the community; and
➢ Negative impact on commercial and residential property values
Impacts to identified assets at risk to this hazard and the overall vulnerability of the District may be affected
in the future by climate change (which was discussed in the Likelihood of Future Occurrence discussion
above), changes in population patterns (migration, density, or the makeup of socially vulnerable
populations), and changes in land use and development. Changes in population patterns and land use, and
the extent to which they affect this hazard, are discussed in the Future Conditions/Future Development
discussion below.
Impacts to identified assets at risk to this hazard and the overall vulnerability of the District may be affected
in the future by climate change. It is likely that climate change will increase the chance of future occurrence
as well as future impacts associated with landslide. Changes in population patterns (migration, density, or
the makeup of socially vulnerable populations) and changes in land use and development, and the extent to
which they affect this hazard, are discussed in the Future Conditions/Future Development discussion below.
Future Conditions/Future Development
Future conditions may be affected by climate change, changes in population patterns (migration, density,
or the makeup of socially vulnerable populations), and changes in land use and development. Findings on
this for the District include the following:
Butte County TWSD Annex S-35
Local Hazard Mitigation Plan Update
September 2024
➢ Climate change is likely to exacerbate future landslide conditions in the District.
➢ While population projections for the area served by the District show additional expected growth, these
anticipated future changes in population are expected to be relatively small, which limits additional
impacts to the District. The District noted it has no control over population changes, it merely reacts
to them by providing additional (or reduced) services.
➢ It is unknown how changes in land use and development will affect landslide in the District’s service
territory. Area planning efforts are in effect to reduce this risk and should be updated as necessary to
continue to address future landslide conditions.
Although new growth and development corridors may fall in areas affected by High or Very High risk of
landslide (shown as classes VII to X), local building codes in effect regarding the siting and construction
of structures in identified hazard areas should limit risk to future development.
Wildfire
Likelihood of Future Occurrence–Highly Likely
Vulnerability–High
Hazard Profile and Problem Description
Wildland fire and the risk of a conflagration is an ongoing concern for the TWSD. Throughout California,
communities are increasingly concerned about wildfire safety as increased development in the foothills and
mountain areas and subsequent fire control practices have affected the natural cycle of fire regimes.
Wildland fires affect grass, forest, and brushlands, as well as structures. Where there is human access to
wildland areas the risk of fire increases due to a greater chance for human carelessness and his torical fire
management practices. Historically, the fire season extends from early spring through late fall of each year
during the hotter, dryer months; however, in recent years, the risk of wildfire has become a year around
concern. Fire conditions arise from a combination of high temperatures, low moisture content in the air
and fuel, accumulation of vegetation, and high winds. These weather conditions can result in red flag (e.g.,
fire weather) days, and can result in PSPS/EPSS events in the District. While wildfire risk has
predominantly been associated with more remote forested areas and wildland urban interface (WUI) areas,
significant wildfires can also occur in more populated, urban areas. There is also the concern of wildfires
occurring in these more remote, forested areas that under certain weather conditions, can extend into areas
not generally considered at a high risk to wildfire. Smoke and air quality also becomes an issue, both from
fires occurring inside and outside of the Butte County Planning Area and the City.
Location and Extent
Wildfire can affect all areas of the District. CAL FIRE has estimated that the risk varies across the District
and has created maps showing risk variance. Following the methodology described in Section 4.3.17 of
the Base Plan, wildfire maps for the TWSD were created. Figure S-7 shows the CAL FIRE Fire Hazard
Severity Zone (FHSZ) in the District. As shown on the maps, FHSZs within the District range from Urban
Unzoned to Very High.
Butte County TWSD Annex S-36
Local Hazard Mitigation Plan Update
September 2024
Figure S-7 TWSD – CAL FIRE Fire Hazard Severity Zones
Butte County TWSD Annex S-37
Local Hazard Mitigation Plan Update
September 2024
Wildfires tend to be measured in structure damages, injuries, and loss of life as well as on acres burned.
Fires can have a quick speed of onset, especially during periods of drought or during hot dry summer
months. Fires can burn for a short period of time or may have durations lasting for a week or more.
Past Occurrences
Disaster Declaration History
There has been 15 federal and 9 state disaster declaration due to fire, as shown in Table S-8.
Table S-8 Butte County – State and Federal Wildfire Disaster Declarations 1950-2024
Disaster Type Federal Declarations State Declarations
Count Years Count Years
Wildfire 15 1999, 2004, 2008 (four), 2017
(four), 2018 (three), 2020 (twice)
9 1961, 1987, 1999, 2017 (three),
2018, 2020 (twice)
Source: Cal OES, FEMA
NCDC Events
The NCDC has tracked 33 wildfire events in the County dating back to 1993.
TWSD Events
An event in the summer of 1998 was of concern to the District. Wildfires in the Concow watershed affected
both the District and those that the District serves. Concow road was closed for the duration of the fire.
Many homeowners lost their homes. One death was reported. The District lost all timber on TWSD
property and to this day due to the lack of trees and plants, the Concow Reservoir receives an excessive
amount of sedimentation.
In November of 2018, the Camp Fire started in Pulga California and burned the majority of the Town of
Paradise and a considerable portion of Concow. Concow Dam itself was not impacted, but Concow
reservoir was. Due to loss of vegetation, during the subsequent rain events, massive amounts of sediment
and debris were carried into the lake. Additionally, burned trees have caused safety issues surrounding the
lake.
The District has approximately 275 dry land acres around Concow Reservoir. This area has been
susceptible to wildfires multiple times in the last 10 years. The mitigation project would consist of removal
of undergrowth and hazardous trees to prevent as much impact from a wildfire as possible.
Climate Change and Wildfire
It is likely that climate change will increase the chance of future occurrence as well as future impacts
associated with wildfire. More information on future impacts to the District can be found in the Future
Conditions/Future Development section of the Vulnerability Assessment below.
Butte County TWSD Annex S-38
Local Hazard Mitigation Plan Update
September 2024
Warmer temperatures can exacerbate drought conditions. Drought often kills plants and trees, which serve
as fuel for wildfires. Warmer temperatures could increase the number of wildfires and pest outbreaks, such
as the western pine beetle. Cal-Adapt’s wildfire tool predicts the potential increase in the amount of burned
areas for the year 2090-2099, as compared to recent (2010) conditions. This is shown in Section 4.3.17 of
the Base Plan. Based on this model, Cal-Adapt predicts that wildfire risk in Butte County will increase
moderately at the end of the century. However, wildfire models can vary depending on the parameters
used. Cal-Adapt does not take landscape and fuel sources into account in their model. In all likelihood, in
the Butte County Planning Area, precipitation patterns, high levels of heat, topography, and fuel load will
determine the frequency and intensity of future wildfire.
Vulnerability to Wildfire
Risk and vulnerability to the District from wildfire is of concern. Wildfires that occur in the District occur
from a variety of both natural and manmade causes. The District can be affected both by fires that start on
or near District lands as well as those that start elsewhere and move into the District. In addition to burning
large areas of land, air quality can be affected in the District by fires occurring inside the District as well as
those from many miles away. As growth continues and populations increase in the District, the potential
for wildfires will also increase.
The whole of the District is at some measure of vulnerability to wildfire. An assessment of a community’s
vulnerability to wildfire begins with an understanding of local exposure to wildfire. This is included in the
Local Concerns section below. After that section, assets at risk are discussed.
Local Concerns
The District has specific concerns and unique vulnerabilities regarding this hazard. These concerns form a
portion of the basis for the mitigation strategy and mitigation actions that seek to reduce vulnerabilities to
this hazard.
Although the physical damages and casualties arising from wildland urban interface fires may be severe, it
is important to recognize that they also cause significant economic impacts by resulting in a loss of function
of buildings and infrastructure. In some cases, the economic impact of this loss of services may be
comparable to the economic impact of physical damages or, in some cases, even greater. Economic impacts
of loss of transportation and utility services may include traffic delays/detours from road and bridge closures
and loss of electric power, potable water, and wastewater services. Fires can also cause major damage to
power plants and power lines needed to distribute electricity to operate District facilities. Power can also
be shut off to the District during Public Safety Power Shutdown events.
Wildfire Smoke and Air Quality
Smoke from wildfires is made up of gas and particulate matter, which can be easily observed in the air. Air
quality standards have been established to protect human health with the pollutant referred to as PM2.5
which consists of particles 2.5 microns or less in diameter. These smaller sizes of particles are responsible
for adverse health effects because of their ability to reach the lower regions of the respiratory tract.
Butte County TWSD Annex S-39
Local Hazard Mitigation Plan Update
September 2024
Wildfire smoke can have negative effects to those who live in or near a fire burn area. Smoke and air
pollution from wildfires can be a severe health hazard. Significant wildfires occurring in both the County
and nearby northern California communities since the 2019 LHMP Update have created significant air
pollution affecting area residents. This was the case during the 2020 North Complex Fire, as well as others
that affected the nearby areas.
Assets at Risk
Assets at risk from wildfire include people and populations served; structures and critical facilities;
community lifelines; natural, historic, and cultural resources; economic assets; and community activities of
value. These are discussed in the following sections.
People and Populations Served
All populations are at some vulnerability to wildfire. Certain vulnerable populations are at greater risk to
the effects of wildfire as well as smoke and air quality issues that wildfires bring. Vulnerable populations
include:
➢ Unhoused
➢ Infants and children under age five and their caregivers
➢ Elderly (65 and older)
➢ Individuals with disabilities
➢ Individuals’ dependent on medical equipment
➢ Individuals who exercise or recreate outdoors
➢ Individuals who work outdoors
➢ Individuals with impaired mobility
Structures and Critical Facilities
All structures in the District have some risk to wildfire. Wildfire presents a threat to critical facilities and
infrastructure. The following assets in Table S-9 were identified by the District as being at risk to wildfire.
Table S-9 TWSD – Facilities at Risk from Wildfire
Name of Asset Facility Type Replacement Value
Concow Reservoir & Dam 97’ High arch cement dam $30,000,000
Water Treatment plant Micro Membrane system $7,320,000
Office and maintenance yard Office and equipment storage & repair $1,100,000
Four deep water wells Three wells are centrifugal
1submersable
$3,000,000
Clearwell Storage Water Storage tank $770,000
2.5 MG Storage Water Storage Reservoir $1,500,000
59 Mile Distribution Pipe system 2” to 30” pipe for water Delivery $38,940,000
34.7 Miles of sewer Collector system 6” to 18” pipe for sewer collection $27,482,400
Sewer Lift Station Pump station $110,000
Butte County TWSD Annex S-40
Local Hazard Mitigation Plan Update
September 2024
Name of Asset Facility Type Replacement Value
Total $110,222,400
Source: TWSD
Community Lifelines
Wildfire presents a threat to life and property, including to community lifelines in the District. Depending
on the severity of the fire, some community lifelines may be overwhelmed. Many of the District’s
community lifelines are the same as or similar to Butte County’s. These were discussed in greater detail in
Section 4.3.17 of the Base Plan.
Natural, Historic, and Cultural Resources
Natural, historic, and cultural resources located within areas at risk to wildfire would be vulnerable. Should
a wildfire occur in the District, the impacts to natural, historic and cultural resources could be extensive and
include air pollution, contamination from water runoff containing toxic products, and other environmental
discharges or releases from burned materials affecting soils, habitat areas, wildlife, and aquatic resources.
Historic and cultural resources can be affected and are often more vulnerable due to their older age,
construction type, and lack of fire prevention infrastructure such as sprinklers.
Economic Assets and Community Activities of Value
Economic assets and community activities of value for the District are similar or the same as those for the
County as a whole. Those assets and activities were discussed in greater detail in Section 4.3.17 of the
Base Plan.
Impacts from Wildfire
Potential impacts from wildfire include loss of life and injuries; damage to structures (commercial,
industrial, and residential) and other improvements, natural and cultural resources, croplands, and timber;
and loss of recreational opportunities. Wildfires can cause short-term and long-term disruption to the
District. Fires can have devastating effects on watersheds through loss of vegetation and soil erosion, which
may impact the District by changing runoff patterns, increasing sedimentation, reducing natural and
reservoir water storage capacity, and degrading water quality. Fires can also affect air quality in the District;
smoke and air pollution from wildfires can be a severe health hazard. Smoke impacts may come from
wildfires outside the District, as well as from within.
Although the physical damages and casualties arising from wildland-urban interface fires may be severe, it
is important to recognize that they also cause significant economic impacts by resulting in a loss of function
of buildings and infrastructure. Economic impacts of loss of transportation and utility services may include
traffic delays/detours from road and bridge closures and loss of electric power, potable water, and
wastewater services. Schools and businesses can be forced to close for extended periods of time. Recently,
the threat of wildfire, combined with the potential for high winds, heat, and low humidity, has caused PG&E
to initiate a PSPS/EPSS which can also significantly impact a community through loss of services, business
closures, and other impacts associated with loss of power for an extended period. In addition, catastrophic
Butte County TWSD Annex S-41
Local Hazard Mitigation Plan Update
September 2024
wildfire can create favorable conditions for other hazards such as flooding, landslides, and erosion during
the rainy season.
The impacts of a fire are felt long after the fire is extinguished. In addition to the loss of property in fires,
the loss in vegetation and changes in surface soils alters the environment. When supporting vegetation is
burned, hillsides become destabilized and prone to erosion. The burnt surface soils are harder and absorb
less water. When winter rains come, this leads to increased runoff, erosion, and landslides in hilly areas.
Impacts that are not quantified, but can be anticipated in large future events, include:
➢ Injury and loss of life;
➢ Commercial and residential structural and property damage;
➢ Disruption of and damage to public infrastructure, utilities, and services;
➢ Damage to roads/bridges resulting in loss of mobility;
➢ Significant economic impact (jobs, sales, tax revenue) to the community; and
➢ Negative impact on commercial and residential property values
Impacts to identified assets at risk to this hazard and the overall vulnerability of the District may be affected
in the future by climate change. It is likely that climate change will increase the chance of future occurrence
as well as future impacts associated with wildfire. Changes in population patterns (migration, density, or
the makeup of socially vulnerable populations) and changes in land use and development, and the extent to
which they affect this hazard, are discussed in the Future Conditions/Future Development discussion below.
Future Conditions/Future Development
Future conditions may be affected by climate change, changes in population patterns (migration, density,
or the makeup of socially vulnerable populations), and changes in land use and development. Findings on
this for the District include the following:
➢ As discussed in the hazard profile section, climate change is anticipated to exacerbate this hazard over
time.
➢ While population projections for the area served by the District show additional expected growth, these
anticipated future changes in population are expected to be relatively small, which limits additional
impacts to the District. The District noted it has no control over population changes, it merely reacts
to them by providing additional (or reduced) services.
➢ It is unknown how changes in land use and development will affect wildfire in the District’s service
territory. Building that occurs in the moderate or higher FHSZ may increase risk to additional lands.
Building codes are in effect to reduce this risk and should be updated as necessary to continue to address
future wildfire conditions.
Additional growth and development within moderate or higher fire hazard severity zones in the District
would place additional values at risk to wildfire. District building codes are in effect and should continue
to be updated as appropriate to reduce this risk.
Butte County TWSD Annex S-42
Local Hazard Mitigation Plan Update
September 2024
S.5 Capability Assessment
Capabilities are the programs and policies currently in use to reduce hazard impacts or that could be used
to implement hazard mitigation activities. This capabilities assessment is divided into five sections:
regulatory mitigation capabilities, administrative and technical mitigation capabilities, fiscal mitigation
capabilities, mitigation education, outreach, and partnerships, and other mitigation efforts.
S.5.1. Regulatory Mitigation Capabilities
Table S-10 lists regulatory mitigation capabilities, including planning and land management tools, typically
used by local jurisdictions to implement hazard mitigation activities and indicates those that are in place in
the TWSD. Note: The District does not have the authority to regulate land use and development within its
jurisdiction. Authority for promulgating and enforcing zoning, land use, and development requirements
falls to counties and incorporated communities. As such development within the District’s jurisdictional
boundaries will conform to the zoning and land use development ordinances and building codes of the
county or incorporated community in which the District is located.
Table S-10 TWSD’s Regulatory Mitigation Capabilities
Plans
In Place
Y/N
Does the plan address hazards? Can the plan be used to
carry out mitigation actions? When was it last updated??
Capital Improvements Plan Y Y
Climate Change Adaptation Plan
Community Wildfire Protection Plan N
Comprehensive/Master Plan N
Continuity of Operations Plan N
Economic Development Plan N
Land Use Plan
Local Emergency Operations Plan Y Y -2021 Emergency Response Plan
Stormwater Management Plan N
Transportation Plan N
Other (describe) Y Overflow Emergency Response Plan
Land Use Planning and Ordinances Y/N
Is the ordinance an effective way to reduce hazard
impacts?
Is the ordinance adequately administered and enforced?
Acquisition of land for open space and
public recreation use
N
Building code Y Y
Flood insurance rate maps N
Floodplain ordinance N
Natural hazard-specific ordinance
(stormwater, steep slope, wildfire)
N
Butte County TWSD Annex S-43
Local Hazard Mitigation Plan Update
September 2024
Subdivision ordinance N
Zoning ordinance N
Other Y Site Plan Review Requirements
How can these capabilities be expanded and improved to reduce risk?
Ensuring proper drainage capacity will prevent street flooding which can inundate the sewer system with storm water
Source: TWSD
S.5.2. Administrative/Technical Mitigation Capabilities
Table S-11 identifies the District department(s) responsible for activities related to mitigation and loss
prevention in TWSD.
Table S-11 TWSD’s Administrative and Technical Mitigation Capabilities
Administration
In
Place
Y/N
Describe capability
Is coordination effective?
Staff
Is staffing adequate to enforce regulations?
Is staff trained on hazards and mitigation?
Is coordination between agencies and staff effective?
Chief Building Official N
Civil Engineer, including dam and levee
safety
Y Y
Community Planner N
Emergency Manager Y Y
Floodplain Administrator N
GIS Coordinator N
Planning Commission
Other
Technical Y/N
Has capability been used to assess/mitigate risk in the
past?
Grant writing N
Hazard data and information N
GIS analysis
Mutual aid agreements Y
Other Y Alarms and telemetry
How can these capabilities be expanded and improved to reduce risk?
In regards to this table, there is very little the District can do. The District will continue to seek other mutual aid
agreements, and to enhance the knowledge base of the emergency manager.
Source: TWSD
Butte County TWSD Annex S-44
Local Hazard Mitigation Plan Update
September 2024
S.5.3. Fiscal Mitigation Capabilities
Table S-12 identifies financial tools or resources that the District could potentially use to help fund
mitigation activities.
Table S-12 TWSD’s Fiscal Mitigation Capabilities
Funding Resource
In Place
Y/N
Has the funding resource been used in past
and for what type of activities?
Could the resource be used to fund future
mitigation actions?
Capital improvements project funding Y N, Y
Community Development Block Grant
Federal funding programs (non-FEMA)
Fees for water, sewer, gas, or electric services Y N, Y
Impact fees for new development Y Y, Y
State funding programs
Stormwater utility fee N
Other
How can these capabilities be expanded and improved to reduce risk?
Current funding levels are adequate to mitigate risk. The District will seek all available additional financial resources to
add to District capabilities.
Source: TWSD
S.5.4. Mitigation Education, Outreach, and Partnerships
Table S-13 identifies education and outreach programs and methods already in place that could be/or are
used to implement mitigation activities and communicate hazard-related information.
Table S-13 TWSD’s Mitigation Education, Outreach, and Partnerships
Program/Organization
In Place
Y/N
How widespread are each of these in your
community?
Community newsletters N
Hazard awareness campaigns (such as Firewise,
Storm Ready, Severe Weather Awareness Week,
school programs, public events)
N
Local news N
Organizations that interact with underserved and
vulnerable communities
N
Social media N
Other
Butte County TWSD Annex S-45
Local Hazard Mitigation Plan Update
September 2024
Program/Organization
In Place
Y/N
How widespread are each of these in your
community?
How can these capabilities be expanded and improved to reduce risk?
In-house education and planning to mitigate risk is on-going. Education of the public is limited to awareness of water
conservation and to call if issues arise within the service area.
Source: TWSD
S.5.5. Other Mitigation Efforts
The District has many other completed or ongoing mitigation projects/efforts that include the following:
There are also multiple action plans that address possible hazards to the District. These are power outage,
flood, winter storms, hurricane/tropical storms, and earthquake.
➢ Water:
✓ Ongoing leak detection efforts, water sampling/testing, replacement of aged infrastructure
✓ Maintenance of vehicles/equipment
✓ Hazardous chemical spill containment procedures/plans
➢ Sewer:
✓ Flushing/cleaning of lines
✓ Pump/equipment maintenance
✓ Sanitary Sewer Overflow training and readiness
➢ Concow:
✓ Facility maintenance
✓ Sediment/debris removal
S.6 Mitigation Strategy
S.6.1. Mitigation Goals and Objectives
The TWSD adopts the hazard mitigation goals and objectives developed by the HMPC and described in
Chapter 5 Mitigation Strategy.
S.6.2. NFIP Strategy
While the District is not an eligible NFIP community and does not participate in the NFIP, some of the
mitigation actions and projects below may contain measures to promote effective floodplain management
throughout the Butte County Planning Area. Even though it does not participate in the NFIP, the District
will support the NFIP actions of the County (and the cities) to the fullest extent possible.
S.6.3. Mitigation Actions
The planning team for the TWSD identified and prioritized the following mitigation actions based on the
risk assessment. Background information and information on how each action will be implemented and
Butte County TWSD Annex S-46
Local Hazard Mitigation Plan Update
September 2024
administered, such as ideas for implementation, responsible office, potential funding, estimated cost, and
timeline are also included. The following hazards were considered a priority for purposes of mitigation
action planning:
➢ Dam Failure
➢ Earthquake
➢ Landslide, Mudslide, and Debris Flow
➢ Wildfire
It should be noted that many of the projects submitted by each jurisdiction in Table 5-4 in the Base Plan
benefit all jurisdictions whether or not they are the lead agency. Further, many of these mitigation efforts
are collaborative efforts among multiple local, state, and federal agencies. In addition, the countywide
public outreach action, as well as many of the emergency services actions, apply to all hazards regardless
of hazard priority. Collectively, this multi-jurisdictional mitigation strategy includes only those actions and
projects which reflect the actual priorities and capacity of each jurisdiction to implement over the next 5 -
years covered by this plan. It should further be noted, that although a jurisdiction may not have specific
projects identified for each priority hazard for the five year coverage of this planning process, each
jurisdiction has focused on identifying those projects which are realistic and reasonable for them to
implement and would like to preserve their hazard priorities should future projects be identified where the
implementing jurisdiction has the future capacity to implement.
Mitigation Actions
Action 1. Concow Dam Structural Assessment & Rehabilitation
Hazards Addressed: Dam Failure
Goals Addressed: 1, 2, 3, 5, 6, 8, 9
Issue/Background: Concow dam was completed in 1921. The dam has not required any significant repairs
since its construction. The dam was recently reclassified as High priority and the District would like to do
a structural analysis of the dam and complete any rehabilitation efforts needed.
Project Description: The project would consist of analyzing the existing dam, identifying any deficiencies
and correcting them.
Other Alternatives: None
Existing Planning Mechanism(s) through which Action will be implemented: None
Responsible Office/Partners: Thermalito Water & Sewer District, Division of Safety of Dams
Benefits (Losses Avoided): Continued use of the Dam
Potential Funding: FEMA (BRIC, HMGP, PDM, and FMA), DoSD, Cal OES
Timeline: In the next 5 years.
Butte County TWSD Annex S-47
Local Hazard Mitigation Plan Update
September 2024
Project Priority (H, M, L): High
Action 2. Vulnerable Main Replacement
Hazards Addressed: Earthquake
Goals Addressed: 1, 2, 3, 5, 6, 9
Issue/Background: The District has water mains which were installed in the 50s. These old steel mains
are vulnerable to earthquakes and are in the process of being replaced.
Project Description: The project would consist of removing and replacing the aged infrastructure.
Other Alternatives: None
Existing Planning Mechanism(s) through which Action will be implemented: Capital Improvement
Plans
Responsible Office/Partners: Thermalito Water & Sewer District
Benefits (Losses Avoided): Mitigate potential water main breaks
Potential Funding: FEMA (BRIC, HMGP, PDM, and FMA), Cal OES, DWR
Timeline: In the next 5 years.
Project Priority (H, M, L): Medium
Action 3. Sediment Removal/Catchment
Hazards Addressed: Landslide, Mudslide, and Debris Flow
Goals Addressed: 1, 2, 3, 5, 6
Issue/Background: The District has contended with sediment intrusion into the inlets of Concow Reservoir
for some time. Sediment deposition increased significantly following the Camp Fire. Approximately 80%
of the reservoirs watershed burned.
Project Description: The project would consist of removing the deposited sediment and creating a barrier
for future sedimentation.
Other Alternatives: None
Existing Planning Mechanism(s) through which Action will be implemented: None
Responsible Office/Partners: Thermalito Water & Sewer District
Butte County TWSD Annex S-48
Local Hazard Mitigation Plan Update
September 2024
Benefits (Losses Avoided): Increase water storage in Concow Reservoir and alleviate negative impacts to
Hoffman Crossing in Concow.
Potential Funding: FEMA (BRIC, HMGP, PDM, and FMA), Cal OES, DWR, SWRCB
Timeline: In the next 5 years.
Project Priority (H, M, L): Medium
Action 4. Wildfire Fuel Reduction
Hazards Addressed: Wildfire
Goals Addressed: 1, 2, 3, 5, 6, 7
Issue/Background: The District has approximately 275 dry land acres around Concow Reservoir. This
area has been susceptible to wildfires multiple times in the last 10 years.
Project Description: The project would consist of removal of undergrowth and hazardous trees to prevent
as much impact from a wildfire as possible.
Other Alternatives: None
Existing Planning Mechanism(s) through which Action will be implemented: None
Responsible Office/Partners: Thermalito Water & Sewer District
Benefits (Losses Avoided): Reduce the risk of wildfire around Concow Reservoir.
Potential Funding: FEMA (BRIC, HMGP, PDM, and FMA), Cal OES, DWR, SWRCB, CAL FIRE
Timeline: In the next 5 years.
Project Priority (H, M, L): High
Appendix D: UWMP 2025 Checklist
Retail
(x = required)
Wholesale
(x = required)Order 2025 Guidebook Location Water Code Section Summary as Applies to UWMP Subject Relevant Submittal Table 2025 UWMP Location
x x 1 Chapter 1 10615 Introduction and overview n/a
x x 1 Chapter 1 10630.5
Each plan shall include a simple description of the Supplier’s plan including water availability, future
requirements, a strategy for meeting needs, and other pertinent information. Additionally, a Supplier Plan preparation n/a
x x 2.1 Section 2.1 10620(b)Plan preparation n/a
x n/a 2.5 Section 2.5 10644 Plan preparation 2-1
x x 2.5 Section 2.5 10644 Plan preparation 2-2
x x 2.5 Section 2.5 10644 Plan preparation 2-3
x x 2.4 Section 2.4 10642 social, cultural, and economic elements of the population within the service area prior to and during Plan preparation n/a
x x 2.4 Section 2.4.2 10620(d)(3)Suppliers that share a common source, water management agencies, and relevant public agencies, to Plan preparation n/a
x n/a 2.4 Section 2.4.1 10631(h)Plan preparation 2-4 R
n/a x 2.4 Section 2.4.1 10631(h)and planned sources of water available from the Wholesale Supplier to the Supplier during various Plan preparation 2-4 W
x x 3.4 Section 3.4.2 10631(a)System description n/a
x x 3.5 Section 3.5 10631(a)System description and n/a
x n/a 4.2 Section 4.2.5.4 10631.1(a)System water use 4-3
x n/a 4.2 Section 4.2.5.3 10631(d)(4)(B)(ii)Supplier shall… Indicate the extent that the water use projections consider savings from codes,
standards, ordinances, or transportation and land use plans. Water use projections that do not System water use 4-3
x x 4.2 Section 4.2.5.6 10635(b)System water use n/a
n/a x 5.1 Section 5.1 10608.36 Baselines and targets n/a
x n/a 5.2 Section 5.2 10608.4
Retail Suppliers shall report on their compliance in meeting their water use targets. Reporting
requirements will vary depending on whether the Supplier:
- Was considered an urban retail water supplier in 2020,
- Met its 2020 target in 2020, or
- Was part of a merger or consolidation since 2020.
Baselines and targets 5-1
x x 6.1 Section 6.1 10631(b)(2)System supplies n/a
x x 6.1 Sections 6.1 and 6.2 10631(b)(1)lasting five years, as well as more frequent and severe periods of drought, including changes in System supplies n/a
x x 6.2 Section 6.2.2 10631(b)(4)(C)groundwater is identified as an existing or planned source of water… (include) a detailed description
and analysis of the location, amount and sufficiency of groundwater pumped by the Supplier for the 6-1
x x 6.2 Section 6.2.2 10631(b)(4)(A)adopted by the Supplier or if there is any other specific authorization for groundwater management. System supplies n/a
x x 6.2 Section 6.2.2 10631(b)(4)(B)System supplies n/a
x x 6.2 Section 6.2.2 10631(b)(4)(B)n/a
x x 6.2 Section 6.2.2.10631(b)(4)(C)and analysis of the location, amount and sufficiency of groundwater pumped by the Supplier for the System supplies n/a
x x 6.2 Section 6.2.7 10631(c)Describe the opportunities for exchanges or transfers of water on a short-term or long-term basis.System supplies n/a
x n/a 6.2 Section 6.2.5 10633(a)System supplies (recycled water)6-2
x x 6.2 Section 6.2.5 10633(b)System supplies (recycled water)6-3
x x 6.2 Section 6.2.5 10633(e)and 20 years, and describe the actual use of recycled water in comparison to uses previously System supplies (recycled water)6-4 and 6-5
x x 6.2 Section 6.2.5 10633(g)Provide a plan for optimizing the use of recycled water in the Supplier's service area.System supplies (recycled water)n/a
x x 6.2 Section 6.2.10 10631(f)water Supplier to address water supply reliability in average, single-dry, and for a period of drought System supplies 6-7
x 7.1 Section 7.1 10634 n/a
x x 7.2 Section 7.2 10635(a)lasting five consecutive water years by comparing the total water supply sources available to the 7-2, 7-3, and 7-4
x x 7.2 Section 7.2.3 10620(f)n/a
x x 7.3 Section 7.3 10635(b)n/a
x x 7.3 Section 7.3 10635(b)(1)that are necessary to conduct a drought risk assessment for a drought period that lasts five n/a
x x 7.3 Section 7.3 10635(b)(2)n/a
x x 7.3 Section 7.3 10635(b)(3)7-5
x x 7.3 Section 7.3 10635(b)(4)and demands under climate change conditions, anticipated regulatory changes, and other locally n/a
x x 8 Chapter 8 10632(a)Provide a water shortage contingency plan (WSCP) with specified elements below.n/a
x x 8.2 Section 8.2 10632(a)(2)(B)n/a
x x 8.3 Section 8.3 10632(a)(3)(A)50% shortage. These levels shall be based on supply conditions, including percent reductions in n/a
x x 8.4 Section 8.4 10632(a)(4)(B)Specify locally appropriate demand reduction actions to adequately respond to shortages.8-3
x x 8.4 Section 8.4 10632(a)(4)(C)Specify locally appropriate operational changes.8-2
x x 8.4 Section 8.4 10632(a)(4)(D)Table 8-3
x x 8.5 Section 8.5 10632(a)(5)(A)n/a
x x 8.5 Section 8.5 10632(a)(5)(B), n/a
x n/a 8.6 Section 8.6 10632(a)(6)Retail Supplier must describe how it will ensure compliance with and enforce provisions of the WSCP.n/a
x x 8.7 Section 8.7 10632(a)(7)(A)Describe the legal authority that empowers the Supplier to enforce shortage response actions.n/a
x x 8.7 Section 8.7 10632(a)(7)(B)Water Shortage Emergencies .n/a
x x 8.8 Section 8.8 10632(a)(8)(B)n/a
x n/a 8.8 Section 8.8 10632(a)(8)(C)Excessive
Residential Water Use During Drought .n/a
x n/a 8.9 Section 8.9 10632(a)(9)appropriate data are collected, tracked, and analyzed for purposes of monitoring customer n/a
x x 8.10 Section 8.10 10632(a)(10)n/a
x n/a 8.11 Section 8.11 10632(b)n/a
x x 8.12 Section 8.12 10632(c)n/a
x n/a 9.1 Sections 9.1 10631(e)(1)Demand management measures n/a
n/a x 9.2 Sections 9.2 10631(e)(2)Demand management measures n/a
x n/a 10 Chapter 10 10608.26(a)n/a
x x 10.2 Section 10.2.1 10621(b)10-1
x x 10.4 Section 10.4 10621(f)Each urban water Supplier shall update and submit its 2025 plan to DWR by July 1, 202 6.n/a
x x 10.2 Sections 10.2.2, 10.3, and 10.5 10642 inspection, published notice of the public hearing, and held a public hearing about the UWMP and n/a
x x 10.2 Section 10.2.2 10642 10-1
x x 10.3 Section 10.3.2 10642 n/a
x x 10.4 Section 10.4 10644(a)(1)n/a
x x 10.4 Sections 10.4.1 and 10.4.2 10644(a)(2)The UWMP, or amendments to the UWMP, submitted to DWR shall be submitted electronically.n/a
x x 10.7 Section 10.7.2 10644(b)If revised, submit a copy of the WSCP to DWR within 30 days of adoption.n/a
x x 10.5 Section 10.5 10645(a)Provide supporting documentation that, not later than 30 days after filing a copy of its UWMP with
DWR, the Supplier has or will make the plan available for public review during normal business hours.n/a
x x 10.5 Section 10.5 10645(b)Provide supporting documentation that, not later than 30 days after filing a copy of its WSCP with
DWR, the Supplier has or will make the plan available for public review during normal business hours.n/a
x x 10.6 Section 10.6 10621(c)n/a
Appendix E: Adoption Resolution