Publication Summary

Fourteen fish tissue samples and five sediment samples were collected from six sites in September 1994 for the Washington State Pesticide Monitoring Program (WSPMP). Tissue samples were analyzed for 43 target pesticides and breakdown products, as well as seven polychlorinated biphenyls (PCBs). Sediment samples were analyzed for 140 pesticides and breakdown products, and four PCBs. Total lipid content was also determined for each tissue sample; and grain size, total organic carbon, and total solids were determined for sediment samples.

Fourteen fish tissue samples and five sediment samples were collected from six sites in September 1994 for the Washington State Pesticide Monitoring Program (WSPMP). Tissue samples were analyzed for 43 target pesticides and breakdown products, as well as seven polychlorinated biphenyls (PCBs). Sediment samples were analyzed for 140 pesticides and breakdown products, and four PCBs. Total lipid content was also determined for each tissue sample; and grain size, total organic carbon, and total solids were determined for sediment samples.

A total of 20 pesticides and breakdown products, as well as two PCBs (Aroclor equivalents), were detected in fish tissue samples. DDT, chlordane, and their metabolites comprised 56-89% of the detections. Four of the detected compounds -- DCPA (Dacthal), ethion, lindane, and methoxychlor -- are currently registered for use in Washington, but actual frequency and quantity of use is not known. Other frequently detected compounds were hexachlorobenzene and PCB-1254 and -1260. Only four pesticides or breakdown products -- 4,4′-DDE, 4,4′-DDD, bromoxynil, and pentachlorophenol -- were found in sediment samples.

Results were compared to USEPA human health screening values, proposed wildlife criteria, and to 85th percentiles calculated from statewide data. Screening values for total DDT and PCBs were exceeded in fillet samples from Lakes Chelan and Sacajawea, and the Palouse and Okanogan Rivers. Total DDT in carp from the Okanogan River was two orders of magnitude higher than the screening value, and one order of magnitude higher in smallmouth bass from Lake Chelan and in channel catfish from Lake Sacajawea. Proposed wildlife criteria for the protection of fish-eating wildlife were exceeded for total DDT in whole largescale sucker samples from all sites except the Soleduck River. Total DDT concentrations in suckers from Lake Chelan and the Entiat and Okanogan Rivers were substantially higher than the proposed criteria, and were well above the state 85th percentile. Total chlordane, hexachlorobenzene, and heptachlor epoxide in fillet and whole fish samples from the Palouse River, and total chlordane and hexachlorobenzene in fillet samples from Lake Sacajawea, also exceeded state 85th percentiles.

Comparisons to data from the U.S. Fish and Wildlife Service indicate that concentrations of contaminants in suckers from Lake Sacajawea have essentially remained the same for 23 years. Differences observed between samples collected by the WSPMP from Lake Chelan in 1992 and 1994 are probably due to differences in average fish size. Chronic contamination problems may be associated with disturbance of contaminated soils, which are carried into streams and lakes by storm-water runoff, and eventually accumulated by fish. It is likely that chlorinated pesticide contamination in fish tissue will continue to be a problem for many years.

Recommendations include an intensive survey for Lake Chelan to evaluate potential human health risks and fisheries impacts, additional sampling for the Entiat River to confirm high concentrations of DDT and to evaluate human health risks, an intensive survey of sport fish in the lower Okanogan River to assess the extent and range of DDT contamination, a study to determine if piscivorous wildlife within the Wenatchee, Okanogan, and Lower Snake watersheds are being adversely impacted by total DDT contamination, and collection of additional sport fish from Lake Sacajawea to assess the impact to human health from multiple contaminants. Development of guidelines for disturbance of soils contaminated with chlorinated pesticides is also recommended.

Link to EIM data for User Study ID WSPMP94T

Link to EIM data for User Study ID WSPMP94S