Summary

Description

Tule Lake and the adjacent Lower Klamath National Wildlife Refuges TLNWR and LKNWR serve as key springfall staging and overwintering areas for Pacific Flyway migratory waterfowl, with as many as 89 million goose and duck use days recorded in the refuges annually. More than 45 different pesticides were allowed for use on the lease lands of these refuges, including some potentially toxic organophosphate insecticides disulfoton and chlorpyrifos, pyrethroids permethrin and cyfluthrin and fungicides chlorothalonil. The following pesticide monitoring study, conducted during the 1998, 1999, and 2000 agricultural seasons was designed to evaluate the acute risks of pesticides used on the refuge, with special emphasis on monitoring at sites where the above pesticides were used. The objectives of this study were 1 to survey both refuges for dead or impaired wildlife, with an emphasis on mortality events innear agricultural areas, 2 to determine whether pesticide exposure is implicated in any death or impairment discovered, and 3 to investigate the source of any pesticide exposure detected.