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We used the 2014 Active Bar Mapping Report (McBain Associates 2015) and the validated SRH-2D hydraulic model (Bradley 2018) to describe coarse sediment storage and investigate relationships between coarse sediment storage and rearing habitat for Chinook Salmon from Lewiston Dam to the North Fork Trinity River (Restoration Reach). The Active Bar Mapping Report was prepared in June 2015 and used active bars as an index of coarse sediment storage in the 64-km TRRP Restoration Reach. The report documented locations, dimensions, and formative histories of active gravel bars, and found preliminary relationships linking gravel bar area and Chinook Salmon juvenile rearing habitat. Juvenile rearing habitat (Chinook Salmon) relationships were also explored using preliminary results from the Trinity River SRH-2D hydraulic model in an 8.6-km subreach between Johnson Point and Oregon Gulch (RKm 139.1–130.5). Results showed a trend of habitat persisting at active bar areas as the flows increased but were limited to the short subreach, and additional evaluation was recommended once the SRH-2D hydraulic model was complete.

The current report presents additional evaluations that expanded the active bar to juvenile rearing habitat relationships to the entire 64-km Restoration Reach. The updated results were used as a companion analysis to the geomorphic evaluations presented in the 2015 report. Findings from both physical and juvenile rearing habitat evaluations are synthesized to provide a basis for recommended future sediment storage conditions, proposing sediment storage targets based on these desired conditions, and providing management recommendations for achieving these targets. Coupled with ongoing habitat quantification efforts and other studies (e.g., sediment transport investigations), information from this investigation can be used to help define desired future channel form and function as part of the River Corridor Management Strategy, as well as inform similar plans for recovering river health and native fish populations to meet the goals of the Trinity River Record of Decision (ROD; DOI 2000).