Monitoring Program Provides Important Information (Since 2003)
Although direct evidence is difficult to come by, the Napa River watershed likely supported a large population of steelhead and possibly Chinook Salmon under historical conditions. The population today is considered to be significantly diminished and thus the condition of the watershed to support these species is called into question. Many restoration projects and programs in the Napa River watershed involve improving conditions for local salmonid populations, including: removal of fish barriers, reduction of sediment into streams, and restoration of stream habitat.
Monitoring fish populations helps to evaluate the effectiveness of these projects to meet their intended goal and allows for more informed decisions regarding future restoration and policy efforts. From 2003 to 2008, yearly snorkel studies were used to evaluate fish populations and distribution. Then, starting in 2009 the RCD began using a rotary screw trap in the Napa River along with fyke nets in key tributaries to obtain more comprehensive information. Results from the monitoring efforts indicate that steelhead salmon have established a stable population despite variability in rainfall and streamflow, that Chinook salmon are present in every year (but in highly variable numbers), and that a very high proportion of fish observed in the Napa River watershed are indigenous, with less than 1% being invasive species.
- Significance: Salmon are an “indicator species” that can tell us about the overall “health” of our watershed, including water quality and aquatic habitat. The RCD monitors fisheries in the Napa River as a way to evaluate watershed conditions over time and for the purpose of informing policy decisions that are aimed at protecting or restoring these fish species.
- Where: Sites throughout the Napa River
- Results: Results indicate that steelhead populations are generally consistent from year to year, that Chinook salmon are present and spawn in the watershed in most every year, and that indigenous fish species far outnumber non-indigenous species.
- Funds: County of Napa, Department of Fish and Wildlife, Department of Water Resources, Gasser Foundation, Wildlife Conservation Commission of Napa
- Partners: Napa River Steelhead, Treasury Wine Estates, National Marine Fisheries Service