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Last Edited: 4/26/2005

Delta Watershed Fish Project
08/2002 -

Mercury, a potent neurotoxin, bioaccumulates in fish in the Sacramento-San Joaquin Delta watershed at levels that may pose health risks to people who consume the fish.  Mercury is prevalent in the Delta watershed due to human activities, such as historic mercury mining in the Coastal range and gold mining in the Sierra Nevada, and naturally occurring deposits.  Once mercury enters an aquatic system, bacteria convert it into a highly toxic form that is readily accumulated by fish and other organisms.  At many locations in the watershed, mercury concentrations in certain species of fish exceed the health-based guidelines set by the U.S. Environmental Protection Agency.  Fish species of particular concern include largemouth bass, striped bass, catfish, and sturgeon.  Based on preliminary data, these fish are commonly caught and consumed by many anglers and their families in the Delta watershed.  Pregnant and nursing women, infants and young children need to be especially careful about limiting their exposure to mercury.  Excessive exposure to mercury can harm the nervous system of the developing baby and children, leading to subtle decreases in learning ability, language skills, attention and memory. 

 §         Needs Assessment

During August 2002-September 2003, the Environmental Health Investigations Branch (EHIB) of the California Department of Health Services (CDHS) conducted a needs assessment to identify specific populations that consume fish caught in the Delta watershed and their awareness, concerns, and information needs in the following five counties: Sacramento, San Joaquin, Lake, Placer, and Yolo.  The five counties were selected based primarily on the following criteria:  (1) high levels of mercury in fish and 2) high levels of fishing activity.  The needs assessment findings are guiding the project’s current and future activities.


§         Project Activities


The Delta Watershed Fish Project is an inter-organizational effort to reduce exposure to mercury and other chemicals in populations that consume fish caught in the Delta watershed.  EHIB, in collaboration with other state and local agencies, tribes, and community-based organizations, is undertaking a number of activities to address this concern:

·         Creating and convening a stakeholder advisory group to involve community members in developing outreach and education activities and materials and in determining fish sampling studies.

·         Conducting public outreach and education to reduce exposure to mercury in fish.

·         Providing training and information to health care providers that serve populations consuming fish from the Delta watershed.

·         Conducting needs assessments with additional groups and in other counties in the Delta watershed.

·         Designing and conducting studies to learn more about the populations that are consuming fish caught in the Delta watershed.


For more information about outreach and education activities, contact:

Sun H Lee or Samira Jones


For more information about research activities, contact:

Alyce Ujihara or Erica Weis

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