HomeMy WebLinkAbout10.09.26 Board Correspondence - FW_ Lake Oroville Community Update - October 9, 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; Ritter, Tami; Simmons, Katie; Stephens, Brad J.;
Sweeney, Kathleen; Teeter, Doug; Zepeda, Elizabeth
Cc:Loeser, Kamie; Cannon, Jamie
Subject:Board Correspondence - FW: Lake Oroville Community Update - October 9, 2026
Date:Friday, October 9, 2026 3:39:57 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, October 9, 2026 1:33 PM
To: Clerk of the Board <clerkoftheboard@buttecounty.ca.gov>
Subject: Lake Oroville Community Update - October 9, 2026
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Lake Oroville Community Update
October 9, 2026
Salmon Spawning Operations
DWR and the California Department of Fish and Wildlife (CDFW) continue spawning
activities for Chinook salmon at the Feather River Fish Hatchery in Oroville. Spring-run
Chinook salmon spawning was completed Sept. 30 with spawning activities for fall-run
starting on Oct. 12.
As part of their 2- to 5-year lifecycle, Chinook salmon juveniles migrate from the Feather
River to the ocean and return to the Feather River as adults to spawn. Fall-run Chinook
salmon start returning as early as July and continue through November. Many make their
way to the Hatchery via the fish ladder, where DWR and CDFW staff process salmon by
collecting, fertilizing, and incubating their eggs, then raising and releasing fish. These fish
raised at the Feather River Fish Hatchery will later be released in the Feather River,
various reservoirs, and San Francisco Bays to support inland and ocean fisheries.
The Feather River Fish Hatchery is a State Water Project facility built in the late 1960s by
DWR to offset impacts to fish migration caused by the construction of Oroville Dam. DWR
owns and maintains the facility and provides funding to CDFW for fish spawning, rearing,
and stocking operations.
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 embankment 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 2 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 1 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.
PHOTO COLLECTION: Thermalito Afterbay Well Replacement
Project
9/28/2026 - Phase 2 of DWR's Thermalito Afterbay Well Replacement project, which is
replacing six of 15 wells along Highway 99. The original wells are at the end of their
service life and pump surface groundwater back into the Afterbay, ensuring that nearby
properties are not inundated with excess groundwater. View the photo gallery on Pixel.
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 30, 2026, are:
Spring-run Chinook salmon (March 4 through June 30): 8,507
Fall-run Chinook salmon (July 1 through present): 24,020
Steelhead: 190
To see previous year data, visit CalFish.org.
Current Lake Operations
Lake Oroville is at 745 feet elevation and storage is approximately 1.56 million acre-feet
(MAF), which is 46 percent of its total capacity and 83 percent of the historical average.
Feather River flows are at 650 cubic feet per second (cfs) through the City of Oroville with
releases from the Thermalito Afterbay River Outlet at 3,850 cfs for a total Feather River
release of 4,500 cfs downstream. Starting Oct. 10, releases from the Outlet will decrease
This email was sent to clerkoftheboard@buttecounty.net from the California Natural Resources Agency
utilizing Granicus Communications Cloud. California Natural Resources Agency, 715 P Street, Sacramento,
CA 95814
reduced to 2,400 cfs. 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 10/8/2026.
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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