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

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. Thus, 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, leading to a pronounced severity of effects.
Summer steelhead enter freshwater between May and October, while winter steelhead enter
between November and April. Spawning generally occurs in late winter or spring. Immediately
after leaving the gravel, swim-up fry usually inhabit shallow water along banks of stream or
aquatic habitats on stream margins. Steelhead rear in a wide variety of freshwater habitats,
generally for two to three years. However, they may possibly reside up to six to seven years in
freshwater environments. Following the rearing period, they smolt and migrate to sea in the
spring.
We expect the proposed uses of carbaryl, carbofuran, and methomyl pesticide products that
contaminate aquatic habitats may lead to both individual fitness level and subsequent populationlevel
consequences. The risk to this species’ survival and recovery from the stressors of the
action is high for carbaryl, carbofuran, and methomyl.
Snake River Basin Steelhead
The SR steelhead DPS includes 23 naturally spawned populations below impassable natural and
man-made barriers in streams in the Columbia River Basin upstream from the Yakima River,
Washington, to the U.S.-Canada border. The Snake River supports about 63% of the naturalorigin
production of steelhead in the Columbia River Basin. The 10-year average for naturalorigin
steelhead passing Lower Granite Dam between 1996 and 2005 is 28,303 adults. Annual
population growth rates show mixed long- and short-term trends in abundance and productivity.
The annual population growth rate is known for eight independent populations and range 0.89 to
1.08. One historical population is likely extirpated.
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