Publication Summary

Best management practices have been implemented by cranberry farmers along the Washington Coast to reduce pesticide concentrations in surface runoff. Water quality sampling was conducted to evaluate compliance with water quality standards during the peak pesticide application period.

Three sites were sampled in the Grays Harbor County ditch, and six sites were sampled in the Pacific County ditch. Samples were collected one week prior to pesticide application, during the week of peak application, and two weeks following application.

Organophosphorus and carbamate pesticides were targeted for evaluation. Data also were made available for chlorinated and nitrogen-containing pesticides that were inadvertently analyzed by the laboratory.

Cranberry farmers along Washington′s coast, in the Grayland to North Cove area, have been implementing best management practices. An evaluation of their effectiveness was conducted to measure compliance with water quality criteria during the peak pesticide application period.

Three sites were sampled in the Grays Harbor County ditch (GHCDD-1) and six sites in the Pacific County ditch (PCDD-1). Samples were collected one week prior to pesticide application, during the week of peak application, and two weeks following application.

Organophosphorus and carbamate pesticides were targeted for evaluation. Data also were made available for chlorinated and nitrogen-containing pesticides that were inadvertently analyzed by the lab.

Past Department of Ecology studies in 1996 and 1998 found concentrations of three organo-phosphorus pesticides – azinphos-methyl (guthion), chlorpyriphos (lorsban), and diazinon – in water from the ditches that exceeded applicable water quality criteria.

During this current study, July 2 through August 1, 2002, concentrations of multiple pesticides were still found to be exceeding water quality criteria. Although it appears some improvements have been made, best management practices have not gone far enough to bring those pesticides found in 1996 and 1998 to levels within water quality criteria during the growing season.

Two pesticides on the 1998 303(d) list for GHCDD-1, parathion and carbaryl, were not detected during this study and are recommended for removal from the list. The chlorinated pesticide DDT was detected at four of six PCDD-1 sites, while metabolites DDE and DDD were detected at one site in GHCDD-1. A high baseline concentration of diazinon was detected in both ditches during the pre-application period. Caffeine, a common domestic waste constituent, was found in both ditches and is likely from septic system inputs.

Link to EIM data for User Study ID RCOO0003