Changes to Trinity River Restoration Program’s environmental flow management approved

Trinity County, Ca. – With support from the Hoopa Valley and Yurok Tribes, the Bureau of Reclamationannouncedapproval of changes to the timing of water releases from Lewiston Dam into the Trinity River.

Reclamation, the Hoopa Valley Tribe, and the Yurok Tribe signed a Finding of No Significant Impact for the Trinity River Variable Flow Project Environmental Assessment following on the recommendation from the Trinity River Restoration Program’s Trinity Management Council. The plan recommends changes to current environmental flow management including a synchronized flow release and increase to baseflows during the wet season. Managing environmental flow is important for improving food sources and habitat for Trinity River salmonids, like salmon and steelhead.

James Lee, Implementation Branch Chief and Acting Executive Director for the Trinity River Restoration Program said, “this approval to move forward marks a big, positive step toward a long-awaited adaptive change for Trinity River anadromous fish populations.”

The implementation window for changes begins on Sunday, Dec. 15, 2024. Below are further details regarding changes to environmental flow management.

Detailed description regarding changes to flow management

1. Synchronized Storm Pulse Period (Dec. 15 – Feb. 15)

This period allows for one synchronized dam release to occur during a significant winter storm event. This water release is designed to match natural river flows, recondition the streambed and help reduce the impact of sediment on salmon eggs from nearby streams.

If an incoming storm is forecast to meet a 4500 cubic feet per second threshold at the gauge located above the North Fork Trinity River then the Trinity River Restoration Program then will announce a “request to Central Valley Operations for a synchronized flow release from Lewiston Dam” via email and social media. Only one synchronized flow will be implemented during this period and the flow schedule is subject to operational constraints at the dams.

To be prepared in anticipation of winter storm events:

• Prevent river trash by moving items away from the riverbank before December 15, 2024.
• To view the trigger prediction tool in anticipation of agency notification click here: CNRFC – Hydrology – River Guidance – Graphical RVF – TRNC1

If triggered, expect an increase in baseflows from Lewiston Dam up to 6,500 cubic feet per second (6,500 cubic feet per second is measured in daily average. Sub-daily flows may exceed 6,500 cubic feet per second). After peak flow, the dam release will decrease to a winter baseflow dependent on the timing of the storm event.

• If you would like to receive Lewiston Dam change order notifications you can sign up here: http://groups.google.com/group/trinity-releases/boxsubscribe
• To follow forecasted storms via National Weather Service, click here: NWS Radar

2. Wet-Season Flood Period (Feb. 16 – April 15)

This increase in flow will provide more food and habitat for juvenile salmon as they prepare to migrate to the ocean. Starting February 16, 2025, baseflows may be increased 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 via email, social media, press releases, and at river access points.

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 [email protected]. An up-to-date daily schedule of flow releases will be available at: http://www.trrp.net/restoration/flows/current

Appropriate precautions checklist

• Move belongings out of the floodway starting December 15, 2024
• 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 email group: Trinity Releases Google Group
  • http://groups.google.com/group/trinity-releases/boxsubscribe
• Follow the TRRP Facebook page: TRRP Facebook Page
  • https://www.facebook.com/trinityriverrestoration

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