Publication Summary

Initiated in 1991 by the Department of Ecology, the Washington State Pesticide Monitoring Program (WSPMP) analyzes ground water, surface water, fish tissue, and sediments for pesticide residues. The results of these analyses are used to provide information on how these residues are distributed in the environment and how these patterns of distribution are changing over time.

Initiated in 1991 by the Department of Ecology, the Washington State Pesticide Monitoring Program (WSPMP) analyzes ground water, surface water, fish tissue, and sediments for pesticide residues. The results of these analyses are used to provide information on how these residues are distributed in the environment and how these patterns of distribution are changing over time.

WSPMP surface water samples were collected at eight sites in April, June, and October of 1994. Sites were selected to represent various pesticide uses including agricultural use west of the Cascade Mountains, irrigated and dry-land agriculture east of the Cascades, use on orchards, urban use, and use by forest practices (Christmas tree farms). Samples were analyzed for 161 pesticides and breakdown products in the following chemical groups: chlorinated pesticides, organo-phosphorus pesticides, nitrogen-containing pesticides, pyrethroid pesticides, chlorinated herbicides, and carbamates. Conventional parameters measured included total suspended solids, total organic carbon, conductivity, nitrate+nitrite, temperature, pH, and flow.

A total of 33 pesticides and breakdown products were detected. The most frequently detected pesticides were 2,4-D, diazinon, dichlobenil, pentachlorophenol, and simazine. Washington State and/or U.S. Environmental Protection Agency (USEPA) aquatic life criteria were exceeded at three sites. Pesticides above criteria were DDT, DDE, azinphos-methyl (Guthion), and chlorpyrifos (Dursban, Lorsban). Levels of carbaryl, diazinon, and malathion exceeded National Academy of Sciences (NAS) recommended maximum concentrations to protect aquatic life and wildlife.

Pesticide use on cranberries in the Grayland area resulted in a high number and frequency of detections in Grays Harbor County Drainage Ditch No.1 (GHCDD-1). Three compounds were detected in all three sample periods and four were found in two periods. Urban use seems to result in a similar pattern of detections. Six pesticides were found in Mercer Creek each of the three years it was sampled. Four additional compounds were identified in two of the years.

Recommendations include additional sampling in GHCDD-1 and urban streams, an intensive survey of streams flowing through orchards to assess impacts of orchard pesticides on biota, development of BMPs for orchard pesticide use, development of state water quality criteria for selected pesticides, addition of Mission Creek to the 303(d) water quality limited list for total DDT, and improved interagency coordination to reduce pesticide related environmental impacts.

Link to EIM data for User Study ID WSPMP94W