The proposed project will establish a monitoring program to assess salmonid populations and instream sediment levels in the Napa River basin. The project directly addresses the recommendations of the Draft Napa River Sediment TMDL to collect current, statistically valid data on steelhead and salmon populations and the related impacts of sediment pollution. The proposed program will provide critical information to state and federal agencies, which will be needed for guiding adaptive updates to the sediment TMDL implementation plan. There has been a long-term decline in salmon and steelhead populations in the Napa River basin, but very little quantitative information has been or is being collected to assess this trend. A few pilot studies have been conducted to examine the relationship of sediment pollution and fisheries declines, but more extensive efforts are needed.
The draft TMDL for the Napa River identifies four beneficial uses as being adversely affected by excess sediment in the Napa River: recreation, cold freshwater habitat, fish spawning, and preservation of rare and endangered species. This project will develop a local monitoring program designed to answer key questions regarding these beneficial uses in the Napa River watershed. The project will provide technical assistance and outreach, in order to protect and recover coldwater fish species (steelhead, chinook salmon) and assess the relative contribution of sediment pollution. A crucial monitoring need in the watershed is the collection of information to allow quantitative estimates of the number and sizes of juvenile salmonids migrating from the watershed toward the ocean under current conditions. Such information is critical for guiding regulatory, management, and restoration efforts that will occur in the Napa River watershed in coming years. The results of this program will be used to generate recommendations for watershed and river riparian management (e.g., best or better management practices) and restoration (e.g., a prioritized list of restoration strategies and actions most likely to improve river ecosystem health and/or maintain or restore species of concern). With this focus, we will be able to rapidly evaluate effectiveness of a variety of management practices implemented to reduce sediment loads, and progress toward attainment of the TMDL.
