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

completing migration to the Pacific during the first year of life, though some overwinter inlowvelocity
pools created by the hydroelectric dams.
Given the life history of SR Fall-run Chinook salmon, we expect the proposed uses of carbaryl
and carbofuran pesticide products may lead to individual fitness level consequences and
subsequent population-level consequences. We expect that exposure to methomyl may lead to
individual fitness consequences, but not to an extent that would affect population growth rates.
Land class data indicate that exposure of the carbamates to SR Fall-run Chinook salmon is
possible. The risk to this species’ survival and recovery from the stressors of the action is high
for carbaryl and carbofuran, but low for methomyl.
Snake River Spring/Summer­run Chinook salmon
This ESU includes 32 historical populations in the Snake River basin which drains portions of
southeastern Washington, northeastern Oregon, and north/central Idaho. Historically, the
Salmon River system may have supported more than 40% of the total return of Spring/Summerrun
Chinook salmon to the Columbia system (Fulton 1968). The long-term trends in
productivity indicate a shrinking population. However, recent trends in productivity, buoyed by
the last five years, are approaching replacement levels. The annual population growth known for
18 populations ranged from 0.97 to 1.1. Historical populations above Hells Canyon are
considered extinct.
The major threats to this ESU identified in the Status of Listed Resources and Environmental
Baseline sections include degraded water quality in the freshwater estuary, tributaries, and
coastal habitats from land use activities and hydroelectric dams. Significant threats to SR
Spring/Summer-run Chinook salmon include elevated temperature, water diversions, and poor
water quality.
Some spawning and rearing areas of the SR Spring/Summer Run Chinook are in forested areas,
where carbaryl may be applied. The likelihood of exposure in forested areas is unknown.
Registered 24(c) uses within this ESU include carbofuran application to potatoes and spinach
grown for seed in Washington. Dryland agriculture occurs in lower Clearwater Basin, with crops
447