Mill Creek is one of three Sacramento River tributaries that supports a self-sustaining, wild population of threatened spring-run Chinook salmon. Mill Creek also supports Central Valley steelhead trout and fall-run Chinook salmon. Due to persistent insufficient instream flow and elevated stream temperatures during summer months, Mill Creek was identified by CDFW as a priority stream for developing passage flow recommendations for Chinook salmon and steelhead trout.
This study assessed stream flows required for adult Chinook salmon and steelhead trout passage through the lower watershed. Passage conditions at depth sensitive, low gradient critical riffles were evaluated using hydraulic habitat modeling and species- and lifestage-specific depth criteria. The effects of stream flow on water temperature were also evaluated using a Stream Network Temperature Model (SNTEMP).
The IFP worked with U.S. Fish and Wildlife Service to complete this study. Results of this study will be used to develop a technical report and evaluate flow regimes needed for salmon and steelhead passage.
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