Publication Summary

During 2006, the Washington State Toxics Monitoring Program analyzed 40 samples of freshwater fish from 14 lakes in Washington. Contaminants frequently detected were mercury, PCBs, dioxins and furans, chlorinated pesticides, and PBDE flame retardants.

Contaminant levels in 27 of the 40 samples (from 11 of the 14 lakes) did not meet Washington State′s water quality standards. Contaminants exceeding standards were PCBs, 2,3,7,8-TCDD, dieldrin, chlordane, hexachlorobenzene, and toxaphene.

Recommendations include (1) evaluation of results to assess risks to human health from the consumption of contaminated fish, and (2) federal Clean Water Act Section 303(d) listings.

The exploratory monitoring component of the Washington State Toxics Monitoring Program (WSTMP) has characterized toxic contaminants in freshwater fish since 2001, primarily from sites never before sampled. Contaminants assessed include persistent, bioaccumulative, and toxic chemicals such as mercury, PCBs, dioxins and furans, chlorinated pesticides, and PBDE flame retardants.

Fourteen lakes were sampled in 2006 and yielded 40 samples representing 13 freshwater species of fish. Most sample results were within the lower range of values found in other studies of fish tissue in Washington.

Mercury and PBDEs were detected in 100%, and PCBs in 55%, of the 40 samples. Pesticides in the DDT and chlordane groups were detected in 75% and 50% of the samples, respectively. The most frequently detected chlorinated pesticides were 4,4′-DDE, 4,4′-DDD, hexachlorobenzene, trans-nonachlor, cis-chlordane, and dieldrin. Other pesticides or breakdown products were detected in less than 10% of the samples.

Only 17 samples were analyzed for dioxins/furans, and all samples had detectable levels.

A total of 20 of the 40 fish tissue samples, from 11 of the 14 lakes, had levels of contaminants higher than (exceeding) the National Toxics Rule (NTR) criteria . Total PCBs and 2,3,7,8-TCDD accounted for 75% of the NTR exceedances. Concentrations of PCBs in 45% of the samples exceeded the NTR criterion, and concentrations of 2,3,7,8-TCDD in 13% of the samples exceeded the criterion. Other exceedances were measured for dieldrin, total chlordane, hexachlorobenzene, and toxaphene.

This study recommends that 11 lakes be added to the federal Clean Water Act Section 303(d) List for Washington State.

This study also recommends that the Washington State Department of Health, local health jurisdictions, and affected tribes should (1) evaluate the levels of toxic contaminants found during this 2006 study, and (2) determine the need for additional sampling to assess the risks to human health from the consumption of contaminated fish.

Link to EIM data for User Study ID WSTMP06