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This report has been prepared to summarize and provide the history, scientific rationale, and anticipated outcomes of the Winter Flow Project (Winter Flow Project or Project) proposed by the Trinity River Restoration Program (TRRP or Program). The Winter Flow Project activities described in this report are designed to support the TRRP’s goal of restoring fish populations to pre-dam levels and restoring dependent fisheries, including those held in trust by the federal government for the Hoopa Valley and the Yurok Tribes, as mandated by Congress and outlined in the 2000 Trinity River Mainstem Fishery Restoration Final Environmental Impact Statement (Trinity River FEIS; USFWS et al. 2000b), and the Record of Decision (USFWS et al. 2000a; Gaeuman and Stewart 2017).

 

The Winter Flow Project, described in detail in Section 2, proposes to shift a portion of the ROD water volume used for restoration releases in the spring to the winter period to improve anadromous fish habitat conditions along the TRRP’s restoration reach, which is the approximately 40-mile length of the Trinity River downstream of Lewiston Dam to the confluence of the North Fork Trinity River (also referred to as the “North Fork”) in Trinity County, California (Figure 1-1).

 

As stated in the Trinity River Flow Evaluation Study (TRFES; USFWS and HVT 1999), “No high-flow release(s) are planned, but synchronization of peak releases with stormflows should be evaluated through the adaptive management program to assess opportunities to maximize benefits of high-flow releases while conserving water.” The Trinity River FEIS and the ROD, however, do not provide a logistical framework necessary to implement changes to the ROD flow regime. This lack of guidance and perceived lack of environmental permitting compliance under the current FEIS has stifled previous efforts to shift flow from the spring period to the winter months. The Winter Flow Project presented in this report provides an operational framework for implementing a winter flow synchronization regime.