To investigate the potential impacts of Martinez Refining Company (MRC) discharging selenium (Se) above its wasteload allocation, the San Francisco Bay Regional Water Quality Control Board (SFBRWQCB) required MRC to monitor for possible effects of selenium on Sacramento splittail and white sturgeon in Carquinez Strait. These fish have been shown to be particularly susceptible to selenium toxicity. In accordance with the SFBRWQCB 13383 letter dated July 12, 2023, San Francisco Estuary Institute was contracted to accomplish the following objectives:

a. collect sturgeon muscle tissue samples, splittail filet and egg-ovary tissue samples, and water samples from Carquinez Strait;
b. analyze sturgeon muscle tissue samples for total selenium, splittail egg-ovary samples for total selenium, and water samples for total selenium, selenite (Se(IV)), selenate (Se (VI)), and organic selenium;
c. compare collected data to the muscle tissue and water column TMDL targets in Basin Plan Table 7.2.4-1; and
d. compare splittail egg-ovary data to literature values.