Publication Summary

High concentrations of multiple pesticides detected in Grays Harbor County Drainage Ditch No.1 (GHCDD-1) in 1994 and 1995 by the Washington State Department of Ecology prompted an intensive survey of water, sediment, and fish and shellfish potentially impacted by drainage from cranberry bogs in the Grayland/North Cove area. The objective of the survey was to determine the extent and severity of pesticide contamination from cranberry farming, and to establish a baseline of pesticide concentrations to assess effectiveness of best management practices (BMPs).

High concentrations of multiple pesticides detected in Grays Harbor County Drainage Ditch No.1 (GHCDD-1) in 1994 and 1995 by the Washington State Department of Ecology prompted an intensive survey of water, sediment, and fish and shellfish potentially impacted by drainage from cranberry bogs in the Grayland/North Cove area. The objective of the survey was to determine the extent and severity of pesticide contamination from cranberry farming, and to establish a baseline of pesticide concentrations to assess effectiveness of best management practices (BMPs).

GHCDD-1 drains bogs in the Grayland area, and discharges into South Bay of Grays Harbor. Pacific County Drainage Ditch No.1 (PCDD-1) drains bogs south of the county line, and discharges into Willapa Bay.

Water samples were collected from each ditch once per week throughout the growing season, and once per day for five days following peak pesticide applications in 1996. Most water samples were analyzed for organophosphorus pesticides only. One of the samples from each ditch collected during the five days after pesticide applications was analyzed for an expanded list of 150 compounds that included most pesticides that are being or have been used on cranberries. One set of tissue and sediment samples was collected in the last week of August 1996. Tissue samples were analyzed for 48 pesticides and PCBs, and sediment samples were analyzed for 133 compounds.

High concentrations of multiple insecticides were detected in water samples collected throughout the growing season. Nearly all detections of three highly toxic organophosphorus insecticides -- azinphos-methyl (Guthion), chlorpyrifos (Lorsban), and diazinon -- exceeded water quality criteria for the protection of aquatic life. Many detections were above LC50 values for some aquatic invertebrates. Azinphos-methyl, chlorpyrifos, and diazinon were found at the highest concentrations ever recorded in state waters.

While these data document a pesticide contamination problem in the drainage ditches, there is little information to determine environmental pathways. More information is needed to identify the routes that transport pesticides into the drainage ditches so appropriate prevention measures can be developed.

Few or no pesticides were detected in tissue samples of shellfish that might be regularly consumed by humans. DDE, a breakdown product of DDT, was found in three samples at low concentrations. PCB-1260 was also found in two samples at low concentrations. Levels of total DDT and total PCBs in these samples exceeded human health screening values calculated based on expected consumption for subsistence fishermen based on a risk level of 1x10-6. Sticklebacks, a non-food fish, contained moderate concentrations of several pesticides and breakdown products, but none exceeded criteria for protection of fish-eating wildlife. Several pesticides were detected in each of the sediment samples collected from the drainage ditches, but only two organophosphorus insecticides -- azinphos-methyl and diazinon -- were found at elevated concentrations.

Recommendations include (1) additional water sampling to identify the routes that transport pesticides into the main drainage ditches, and (2) after steps have been taken to reduce pesticide levels, water samples should be collected to confirm effectiveness of BMPs.

Link to EIM data for User Study ID CRAN96