In 2016, the State Water Resources Control Board approved a selenium TMDL for North San Francisco Bay. The TMDL established a target concentration of 11.3 ug/g dw in white sturgeon muscle tissue as the basis for evaluating impairment (SFBRWQCB 2015). Following discussions surrounding the North Bay TMDL, the San Francisco Bay Regional Water Quality Control Board asked the RMP Selenium Workgroup to develop a robust monitoring design for North Bay.
The goal of the monitoring is to identify leading indicators of change to allow prompt management response to signs of increasing impairment. At the 2016 technical workshop, participants reached a consensus that monitoring sturgeon, clams, and water are all needed to answer management questions. Recommendations for long-term monitoring of these three matrices are detailed in the North Bay Monitoring Design document (Grieb et al. 2018).
The USGS conducted monthly clam monitoring at multiple locations in North Bay for over 20 years, but USGS funding for this work ended in 2016. In 2019, the RMP will resume clam monitoring following a modified monitoring design optimized for early detection of changes in selenium trends in clams. These efforts will continue the long-term monitoring of Potamocorbula amurensis. Grieb et al. (2018) also recommended monitoring dissolved and particulate selenium in the water column. Long-term monitoring of water and sturgeon tissue in North Bay will be added to the clam sampling to track interannual trends and changes in sources or environmental processes influencing food web selenium exposures in North Bay.
Potamocorbula amurensis and water samples will be collected from two long-term USGS monitoring locations in northern San Francisco Bay. Samples will be collected and processed by SFEI and Applied Marine Sciences (AMS) aboard the R/V Questuary . Sampling will take place over six months each year in two key three-month periods: July-September and December-February. White sturgeon ( Acipenser transmontanus ) samples will be collected by DFW during their tagging efforts aboard the New Alosa . These efforts occur during DFW’s fall tagging cruises (Sept – Oct). Non-lethal muscle plug samples will be collected from the epaxial muscle of each fish, just in front of the dorsal fin (Figure 5). Brooks Applied Labs (BAL), CalTest Analytical Laboratory (CalTest), and the UC Davis Stable Isotope Lab will be the analytical partners for this work. Stable isotope analysis will be used to identify spatial and temporal relationships within a food web, as well as potential sources of selenium. BAL will analyze dissolved and particulate selenium in water; clams, and sturgeon samples; and CalTest will conduct ancillary analyses on dissolved water samples. The purpose of this Sampling and Analysis Plan is to clearly document the sampling design, methods, and responsibilities; and to facilitate coordination among project partners.