Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

Chinook salmon. Furthermore, there has been extensive urbanization in this region. Well over
two million people inhabit the area, with most development occurring along rivers and coastline.
Pesticide use and detections in the ESU’s watershed are well documented. NAWQA sampling
conducted in 2006 in the Puget Sound basin detected numerous pesticides and other synthetic
organic chemicals in streams and rivers. However, mixtures of chemicals found in agricultural
and urban settings differ. Urban streams sampled in Puget Sound showed the highest detections
for carbaryl, diazinon, and malathion. Carbaryl was detected at 60% of urban sampling sites
(Ebbert, Embrey et al. 2000). Diazinon was detected at all urban sites, frequently at
concentrations that exceeded EPA guidelines for protecting aquatic life (Bortleson and Ebbert
2000).
Registered uses of carbaryl, carbofuran, and methomyl include applications to crop agricultural
sites, residential sites, and urban sites. In addition, Washington has 24(c) registrations for
carbofuran use on spinach grown for seed and potatoes. Land classes indicate high-use of the
three a.i.s in the following drainage basins: Nooksack, Skagit River, Stillaguamish, Skykomish,
Snoqualimie, Snohomish, Lake Washington, Duwamish, and Puyallup. Roughly 7% of the
lowland areas (below 1,000 ft elevation) in the Puget Sound region are covered by impervious
surfaces, which increase urban runoff containing pollutants and contaminants into streams.
Pollutants carried into streams from urban runoff include pesticides, heavy metals, PCBs,
PBDEs, PAHs, pharmaceuticals, nutrients, and sediments. As such, we expect salmonid
populations within the ESU to be exposed to carbaryl, carbofuran, and methomyl. Further,
monitoring data shows that we can expect concurrent exposure with other AChE inhibiting
chemicals, which will exacerbate the severity of effects. Adults within Willapa Bay during 24(c)
carbaryl application to oyster beds are likely exposed to this compound and may experience
additional mortalities.
Puget Sound stream-type Chinook salmon fry typically rear in shallow off-channel habitats
associated with their natal rivers and streams. Juveniles generally have long freshwater
residences of one or more years before migrating to the ocean.
443