HomeMy WebLinkAbout09.11.26 Board Correspondence - FW_ Lake Oroville Community Update - September 11, 2026.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; Dubose, Teri; Durfee, Peter; Jessee, Meegan;
Kimmelshue, Tod; Kitts, Melissa; Krater, Sharleen; Lee, Lewis; Pickett, Andy; Ritter, Tami; Stephens, Brad J.;
Sweeney, Kathleen; Teeter, Doug; Zepeda, Elizabeth
Cc:Cannon, Jamie; Loeser, Kamie
Subject:Board Correspondence - FW: Lake Oroville Community Update - September 11, 2026
Date:Friday, September 11, 2026 4:08:03 PM
Attachments:image001.png
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: Department of Water Resources <DWRMedia@public.govdelivery.com>
Sent: Friday, September 11, 2026 2:07 PM
To: Clerk of the Board <clerkoftheboard@buttecounty.ca.gov>
Subject: Lake Oroville Community Update - September 11, 2026
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Lake Oroville Community Update
September 11, 2026
Feather River Floating Classroom
Feather River Floating Classroom raft tours are returning this fall! Sponsored and
developed by DWR, the Floating Classroom program guides participants through Feather
River spawning habitat while DWR and Pacific States Marine Fisheries Commission
scientists describe Chinook salmon conservation efforts supported by the State Water
Project. Discussion topics include ongoing and planned research, restoration and
monitoring projects, and fisheries management activities.
Free floating classroom tours start Sunday, Sept. 27 during the Salmon Festival weekend,
followed by tours each Saturday between Oct. 3 and Nov. 7. Each weekend will have
two public tours with limited seats. Tickets will be released each Friday, approximately two
weeks in advance of each tour, and are available on a first-come, first-served basis with
up to four free tickets available per person each fall. Reserve your FREE
floating classroom ticket(s) on Eventbrite.
Well Project Ongoing Near Thermalito Afterbay Dam
The Thermalito Afterbay is a 57,000 acre-foot, off-stream reservoir contained by the
Thermalito Afterbay Dam and is part of DWR’s State Water Project facilities in Oroville.
Construction on the Afterbay began in 1966 and was completed in 1967.
It stores water that flows through the Thermalito Pumping-Generating Plant during power
generation and provides controlled releases to the Feather River and irrigation water to
over 150,000 acres of local farmland.
The need for managing seepage at the Afterbay was recognized during planning, design,
and construction. Beginning in 1957, groundwater levels were measured and recorded
to establish data for comparing pre- and post-Afterbay conditions. With the initial filling of
the Afterbay reservoir in 1967, additional water percolated into the aquifer causing
groundwater levels to rise downstream of the dam. DWR installed 15 shallow wells
spaced 1,000 to 3,000 feet apart to manage groundwater levels in the upper
aquifer. The original installed wells are at the end of their service life.
Work is underway on Phase II of DWR's Thermalito Afterbay Well Replacement project,
which is replacing six wells along Highway 99. This project concludes replacement of the
remaining operational wells that were not replaced during the Phase I project in 2008.
DWR anticipates completing well drilling in October with plans to resume construction
work next year to finish the installation of pumps, motors, piping, and electrical equipment.
DWR continues to measure, record, and monitor groundwater levels downstream of the
Afterbay Dam weekly to ensure the ongoing safety of the facility.
Caution Advisory Issued for Lake Oroville’s Middle Fork
DWR has issued a caution advisory for Lake Oroville’s Middle Fork due to a visible algal
bloom between Bean Creek Bar and the inlet near Bald Rock Canyon. DWR staff are
collecting samples for laboratory analysis. A caution advisory will remain in place until the
bloom dissipates.
There is no sure way to tell if an algal bloom is toxic just by looking at it, but there are
indicators that a bloom may be harmful.
Small blue-green, green, white, or brown particles in the water
Streaks in the water that look like spilled paint
Mats, scum, or foam at the surface or along the shoreline
Can have an odor described as gasoline, septic, or fishy
Blue-green algae (cyanobacteria) is a natural component of ecosystems. Under certain
conditions, including warmer temperatures and increased nutrient loads, algae can grow
rapidly causing “blooms.” Algal blooms sometimes produce toxins that can be harmful to
people and animals.
Take these precautions in affected Middle Fork areas for your safety:
Swimming is allowed but stay away from algae and scum in the water and on the
shore.
Do not drink lake water or use it for cooking.
Do not let pets and other animals go into or drink the water or eat scum on the
shore.
For fish caught here, throw away guts and clean fillets with tap water or bottled
water before cooking.
Do not eat shellfish from this water.
DWR’s environmental scientists routinely monitor for blue-green algae and their
toxins within the Oroville-Thermalito Complex. Regular monitoring occurs during the
summer months with water samples taken at various locations, which are sent to a lab for
toxin analysis. If elevated levels of cyanobacteria toxins are found while testing, DWR staff
will work with California’s Regional Water Quality Control Board and recreation area
managers to notify the public and post advisory signs at affected waterbodies. To learn
more about HABs, or to report a HAB visit the Water Board’s website.
Feather River Fish Monitoring Station
DWR resumed operations of the Feather River fish monitoring station on March 4,
2026, to capture the return of spring-run Chinook salmon. Monitoring was temporarily
suspended at the end of December 2025 due to anticipated high flows in the Feather
River. Upstream migrating fish totals between March 4 and September 5, 2026, are:
Spring-run Chinook salmon (March 4 through June 30): 8,509
Fall-run Chinook salmon (July 1 through present): 7,133
Steelhead: 41
To see previous year data, visit CalFish.org.
Current Lake Operations
Lake Oroville is at 776 feet elevation and storage is approximately 1.85 million acre-feet
(MAF), which is 54 percent of its total capacity and 92 percent of the historical average.
This email was sent to clerkoftheboard@buttecounty.net from the California Natural Resources Agencyutilizing Granicus Communications Cloud. California Natural Resources Agency, 715 P Street, Sacramento,
CA 95814
with releases from the Thermalito Afterbay River Outlet at 5,850 cfs for a total Feather
River release of 6,500 cfs downstream. DWR continues to assess Feather River releases
daily.
The public can track precipitation, snow, reservoir levels, and more at the California Data
Exchange Center. The Lake Oroville gage station is identified as “ORO.”
All data as of 11:59 p.m. on 9/10/2026.
California Department of Water Resources
715 P Street
Sacramento, CA 95814
Call our general information line at 916-820-8142
or email us at oroville@water.ca.gov
Contact Us
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