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

Given the life history of LCR Chinook salmon, we expect the proposed uses of carbaryl,
carbofuran, and methomyl pesticide products may contaminate aquatic habitats and lead to
individual fitness and subsequent population-level consequences. Therefore, the risk to this
species’ survival and recovery from the stressors of the action is high for carbaryl, carbofuran,
and methomyl.
Upper Columbia River Spring­run Chinook salmon
The UCR Spring-run Chinook salmon ESU includes 11 populations and 7 artificial propagation
programs in the state of Washington. The four known annual population growth rates range
from 0.99 to 1.1. Based on 1980-2004 returns, the average annual population growth rate for this
ESU is estimated at 0.93. One historical population is considered extinct.
The major threats to UCR Chinook salmon identified in the Status of Listed Resources and
Environmental Baseline sections include reduced tributary stream flow and impaired fish
passage from hydroelectric dams. Additionally, degradation of the tributary habitat and impaired
water quality from development negatively affect this ESU. Pesticide detections in UCR
Chinook salmon freshwater habitats are well documented. NAWQA sampling from 1992-1995
in the Central Columbia Plateau detected numerous pesticides in surface water (Williamson,
Munn et al. 1998). Carbaryl was detected in 5% of samples, and carbofuran was detected in 6%.
Methomyl was not detected. While detections of these three chemicals did not exceed water
quality standards, concentrations of six other pesticides exceeded EPA criteria for the protection
of aquatic life. Listed salmonids are commonly exposed to combinations of carbaryl, carbofuran,
and methomyl, other compounds, and other mixtures of cholinesterase-inhibiting insecticides.
Registered uses of carbaryl, carbofuran, and methomyl include applications to crop agricultural
sites, residential sites, and urban sites. Registered 24(c) uses in Washington State include
carbofuran application to potatoes and spinach grown for seed. About 3% of the land has been
developed and 3.5% has been cultivated for crops. Areas with the potential for high exposure in
the Upper Columbia River basin are the Methow, Entiat, and Wenatchee River basins.
441