Trinity River Water Year 2026 Flow Management
Abel, Kiana
Trinity River Water Year 2026 Flow Management
TRINITY COUNTY, Calif. – Trinity River flows will begin fluctuating this month as the environmental flow schedule approved by the Trinity Management Council is implemented for the second year in a row. The schedule encompasses flow management for the 2026 water year which runs from Oct. 1, 2025, through Sept. 30, 2026. The recommendation was given final approval by the Department of the Interior’s representatives for the Trinity River Restoration Program, the U.S. Fish and Wildlife Service and the Bureau of Reclamation, in October. The approval encompasses functional management, a strategy that combines recreational, managerial and ecological objectives with the end goal of improving habitat conditions for juvenile fish, like salmon and steelhead, that travel to the ocean to grow.
Flows are scheduled from Lewiston Dam at a baseflow of 300 cubic feet per second. Monday, Dec. 15 marks a change in period, the Synchronized Flow Period, which includes the potential of one scheduled release to synchronize with a forecasted winter storm. This period is followed by an increase in baseflows during the wet season. Below are further details regarding Water Year 2026 environmental flow management.
Detailed description regarding Water Year 2026 flow management
Synchronized Storm Pulse Period (Dec. 15 - Feb. 14)
This period allows for one synchronized dam release to occur to match a significant winter storm forecasted for the area. This action is designed to match natural tributary flows, to help recondition the streambed and to reduce the impact of storm-induced sediment deposits from nearby streams on incubating salmon eggs.
If an incoming storm is forecast to meet a 4,500 cubic feet per second threshold at the gauge located above the North Fork Trinity River, then the Trinity River Restoration Program will announce, “a request to Central Valley Operations for a synchronized flow release from Lewiston Dam”. Only one synchronized flow can be implemented during this period, and the request is subject to Central Valley operational constraints.
If the trigger occurs, expect an increase in baseflows from Lewiston Dam within 2 to 5 days of the request. Anticipate a release of approximately 6,500 cubic feet per second from Lewiston Dam (sub-daily flows may exceed 6,500 cubic feet per second). After peak flow, the dam release will steadily decrease to baseflow. Anticipate the river to decrease in flow dependent on the actual timing and magnitude of the natural storm event, ancillary flow scheduling from the Bureau of Reclamation, and/or your location on the Trinity River.
Wet-Season Flood Period (Feb. 15 – Apr.14)
This period aims to provide wetted areas for benthic macroinvertebrate growth, food for juvenile salmon, and habitat as salmon prepare to migrate to the ocean. Starting Feb. 15, 2026, baseflows may be scheduled to increase based on water supply forecasts from the California Department of Water Resources (90% B120 Determination). Daily average flow releases will be communicated in early February and again in early March.
Snow Melt Peak and Recession (Apr. 15 – variable)
In early April, the Program plans to implement spring snowmelt releases, with the remaining water allocation provided to the Trinity River for ecological purposes. The amount released is based on five water year types (extremely dry, dry, normal, wet, extremely wet) and are determined by the California Department of Water Resources’ B120 water year determination.
For questions, please contact the Trinity River Restoration Program office at 530-623-1800 or email your question to in...@trrp.net. An up-to-date daily schedule of flow releases will be available at: http://www.trrp.net/restoration/flows/current
Appropriate precautions checklist
- Prevent river trash and move belongings out of the floodway prior to Dec. 15, 2025
- Check flows and temperatures regularly when planning to recreate on the river
- Maintain infrastructure within the floodplain
- Sign up for notifications from the Trinity River Restoration Program
Ways to stay informed
- Join the Trinity Releases Google Group for Lewiston Dam change order notifications
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Follow the TRRP Facebook page: TRRP Facebook Page
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Follow forecasted storms via National Weather Service, click here: NWS Radar
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Bookmark California-Nevada River Forecast Center - Trinity River North Fork Guage: River Guidance - Graphical RVF - TRNC1
