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Washington State Department of Agriculture’s (WSDA) 2017 Pesticide Monitoring Results in Bertrand Creek and Continuing 2018 Monitoring

Volume 7 Issue 5

WSDA, Natural Resources Assessment Section

Surface Water Pesticide Monitoring Program


The Washington State Department of Agriculture (WSDA) will monitor pesticides in Bertrand Creek starting in March, 2018. The two sampling sites are at the H Street Road (Upper Bertrand Creek) and Rathbone Road (Lower Bertrand Creek) bridges. This is the sixth consecutive year WSDA has monitored Bertrand Creek as part of a larger study testing for pesticides in salmon-bearing streams statewide during typical pesticide use periods (March – October).

In 2017, WSDA monitored Bertrand Creek from March – September for a total of 26 visits.

At Upper Bertrand Creek, WSDA detected 31 different compounds, with 218 total detections. The compounds detected at least 50% of the time were boscalid (a fungicide with common tradenames including Pristine, Endura, and Emerald), carbendazim (a breakdown product of the fungicide benomyl), dichlobenil (an herbicide included in the product Casoron), 2,6-dichlorobenzamide (a breakdown product of dichlobenil), and simazine (a common herbicide included in the product Princep). Of the 218 total detections, 12 were higher than WSDA’s assessment criteria. WSDA’s assessment criteria are related to state and federal water quality criteria. When a detection exceeds WSDA’s assessment criteria, it is approaching levels that may result in harm to aquatic life. The three compounds exceeding these criteria were imidacloprid (an insecticide found in a variety of products), malathion (an organophosphate insecticide) and simazine.

At Lower Bertrand Creek, WSDA detected 37 different compounds, with 284 total detections. The compounds detected 50% or more of the time were 2,6-dichlorobenzamide, boscalid, dichlobenil, metalaxyl (a fungicide with trade names including Metastar), metolachlor (an herbicide found in the products Helmet, Parallel, and Stalwart), oxamyl (a carbamate insecticide used in Vydate) and its breakdown product, and thiamethoxam (a neonicotinoid insecticide found in Actara, CruiserMaxx, Flagship, and Platinum). Of the 284 total detections, eight exceeded WSDA’s assessment criteria: all were detections of imidacloprid and malathion.

In 2018, WSDA will test for 144 pesticide compounds including insecticides (neonicotinoids, pyrethroids, organochlorines, organophosphates, carbamates, and others), herbicides, fungicides, wood preservatives, historically-used pesticides, and breakdown products. In addition, WSDA monitors total suspended solids, stream flow, pH, dissolved oxygen, conductivity, and continuous air and water temperature at all site visits.

WSDA, the Environmental Protection Agency, and the National Marine Fisheries Service use this data to improve exposure assessments for pesticides registered for use in Washington. Visit WSDA’s website for more information and reports from other areas:

Preventing contamination of surface water is critical for protecting aquatic systems and fish. Using pesticides according to their label instructions and paying attention to environmental hazard and precautionary label statements helps protect fish and the environment. Carefully plan pesticide applications and take into account the presence of backyard drains, impervious surfaces, sprinkler timing, and any potential for drift and runoff.