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Soil Investigations for Data Collection in the Delta Initial Study/Proposed Mitigated Negative Declaration 86 ocean. Nobriga and Cadrett (2001) verified these temporal findings (spring migration) based on analysis of captures in USFWS salmon monitoring conducted near Chipps Island. Overall, designated in-water work windows would reduce exposure of sensitive fish species and life stages to in-water work activities. The activities of the Proposed Project would be minor in scope and would not result in degradation of aquatic habitat or water quality conditions and any potential effects related to potential increase in suspended sediment concentrations and contaminants due to disturbance of the river bed would be negligible. Implementation of Mitigation Measures MM BIO-14, along with MM HYD-1 and MM HAZ-1 through 4 would reduce potential impacts to steelhead to: Less than Significant with Mitigation Incorporated. Chinook Salmon – Central Valley Spring-run ESU (Oncorhynchus tshawytscha) The Central Valley (CV) spring-run Chinook salmon ESU is listed as a threatened species under FESA. CV spring-run Chinook salmon are also listed as threatened under CESA. The ESU includes all naturally spawned populations of spring-run Chinook salmon in the Sacramento River and its tributaries in California, and the Feather River Hatchery spring-run Chinook program. As described in the latest NMFS 5-Year Review for Central Valley spring-run Chinook salmon, the status of the ESU has probably improved since the previous status review. Both the Mill and Deer Creek independent populations have improved from high extinction risks to moderate extinction risks, while the Butte Creek population remains at low risk. Nevertheless, the ESU remains classified as threatened (NMFS 2016b). Chinook salmon exhibit two generalized freshwater life history types (Healey 1991). Stream-type adults enter fresh water months before spawning and juveniles reside in fresh water for a year or more following emergence, whereas ocean-type adults spawn soon after entering fresh water and juveniles migrate to the ocean as fry or parr in their first year. Adequate instream flows and cool water temperatures are more critical for the survival of Chinook salmon exhibiting a stream-type life history due to over-summering by adults and/or juveniles. Spring-run Chinook salmon are somewhat anomalous in that they have characteristics of both stream- and ocean-type races (Healey 1991). Adults enter fresh water in early-late spring, and delay spawning until late summer or early fall (stream-type). However, most juvenile spring-run Chinook salmon migrate out of their natal stream after only a few months of river life (ocean-type), or they may remain for up to 15 months within their natal stream. This life-history pattern differentiates the spring-run Chinook from other Sacramento River Chinook runs and from all other populations within the range of Chinook salmon (Hallock and Fisher 1985). Spring-run Chinook salmon emigration timing is highly variable, as they may migrate downstream as young-of-the-year or as juveniles or yearlings. The modal