San Francisco Bay was placed on the State of California’s 303(d) list of impaired waters in 1998 as a result of elevated concentrations of dioxins and furans (commonly referred to as ‘dioxin’) in fish. RMP studies of contaminants in Bay sport fish conducted every three years since 1994 have found that dioxin concentrations have remained unchanged over this time period and in some species, continue to greatly exceed screening values for human consumption. Our understanding of dioxin in the Bay is extremely limited, however, and improving this is a necessary first step in reducing concentrations in Bay fish and resultant health risks to fish-eating humans and wildlife.

Dioxin Strategy Questions

Recognizing that there was a dearth of information, RMP stakeholders developed a Dioxin Strategy in 2008 that prioritized the information needs and articulated a series of studies to be undertaken over the next five years. The RMP has conducted analyses of dioxin in sport fish, bird eggs (cormorants) tributaries, surface water and shallow sediments, and sediment cores to begin to address the following Dioxin Strategy questions:

  1. Are the beneficial uses of San Francisco Bay impaired by dioxins?
  2. What is the spatial pattern of dioxin impairment?
  3. What is the dioxin reservoir in Bay sediments and water?
  4. Have dioxin loadings/concentrations changed over time?
  5. What is the relative contribution of each loading pathway as a source of dioxin impairment in the Bay?
  6. What future impairment is predicted for dioxins in the Bay?


Dioxin Synthesis Document


A synthesis of RMP dioxin studies is expected for 2015.

Staff Involved

Don Yee



Programs and Focus Areas: 
Clean Water Program
Data Services
Location Information