Hoopa Tributary Spawning Gravel Assessment - Hoopa Reservation

Substrate composition is a major component of spawning habitat. Many streams on the North Coast of California were channelized by the Army Corps of Engineers after the 1964 flood. This made the creeks very efficient at transporting water and sediment, which led to over coarsened streambeds. These abundance of large substrates in the transition zones between pool and riffle mesohabitats reduces the quality and quantity of spawning habitat. Post restoration stream evolution has demonstrated a discrepancy in sediment supply and what is incorporated into the streambed. Pre restoration conditions have an abundance of large cobbles and boulders with fine sediment infill. Post restoration has a more uniform distribution from sand to boulder. In 2009 and 2010 Hoopa Yurok and US Fish and Wildlife Service conducted a joint field study on spawning habitat preference in the Trinity River. The final result was a predictive model. One of the variables for that model is percent of gravel with a D84 between 11 and 90mm. We propose to take 8 bulk samples in the appropriate meso habitats longitudinally distributed along 5 streams in the Hoopa Valley and characterize their composition. In the same streams high flow bedload samples would be collected and characterized. Existing lidar and post construction topographic surveys will be used to describe stream measurements such as bankfull width, valley width, and channel slope. Bulk samples outside the range of acceptable spawning measures could be the result of channel form, sediment load, or both. This work will identify the issues and facilitate targeted prescriptions for each stream and each reach.

Project Objective: There are 6 major spawning tributaries that flow into the Trinity River on the Hoopa Valley Reservation. There have been habitat and floodplain projects on the valley floor on the two largest creeks, Mill and Supply, a retrofitted culvert under Highway 96 on Campbell Creek to address a passage issue in 2022, and another passage project in Soctish Creek will be completed in 2023. All of these actions improve access to, and quality of, habitat for SONCC Coho and chinook salmon. The purpose of this effort would be to evaluate the condition and composition of the stream bed substrates relative to spawning needs and compare that to what is being delivered by the upslope reaches of the watersheds. This information will inform site selection for future work.Project Benefits: A more refined understanding of the sediment dynamics in the stream will help guide site specific restoration actions into the future. Future projects tailored to these data will promote increased quantity and quality of spawning habitat not just on the valley floor but in the upslope regions, which will lead to increased survival of the wild salmonids the Hoopa Valley Tributaries support.



Priority Two – Restoration effectiveness monitoring at the watershed scale for Southern Oregon Northern California Coho Salmon and other fish species important to the exercise of federally-recognized tribal fishing rights (SONCC Recovery Actions Addressed: SONCC-LTR.27.1.22.1