Sierra Fish Tissue Study

Without adequate data, the Office of Environmental Health Hazard Assessment (OEHHA) is unable to provide site-specific safe eating guidelines for fish at mercury-impacted water bodies in the Gold Country.


Mercury, a remnant of the Gold Rush, enters the food web and contaminates fish. Some species of fish in Sierra Nevada water bodies contain levels of mercury that are unsafe for sensitive population groups, including women and children, to eat. Many water bodies in the Sierra lack the required fish tissue samples for OEHHA to develop site-specific consumption advisories. Without this information, people who catch and consume fish locally do not have safe eating guidelines specific to where they fish.

Source: OEHHA. While the above statewide advisory was developed to be extremely protective of public health, site-specific advice is preferred because it most accurately reflects the mercury levels in fish in a specific reservoir.


Since 2015 The Sierra Fund (TSF) has identified water bodies without site-specific advisories and collected fish tissue data to inform fish consumption advisories.  TSF has raised awareness about water bodies in need of site-specific advisories, developed an OEHHA-approved Sampling and Analysis Protocol, caught fish and sent the fish to an EPA-certified laboratory for mercury analysis.


TSF has collected enough fish to allow OEHHA to develop site-specific advisories with safe eating guidelines for multiple species of fish for three Sierra Nevada water bodies lacking site-specific advice. In 2018 OEHHA also issued site-specific advice for two local rivers and a creek.

Next Steps

The Sierra Fund is working to compile the fish tissue data we have collected to upload to a publicly accessible database (CEDEN – California Environmental Data Exchange Network). This will allow for easy data transfer to OEHHA for use in developing site-specific fish consumption advisories and makes the information available to interested stakeholders.  We are working to identify additional fish tissue data gaps in our region to ensure that data is collected from other high priority sites.

Project Funders

Past and present project funders include:  True North Foundation, the California Wellness Foundation, the Clarence E. Heller Charitable Foundation and the California Department of Water Resources.