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

Based on the crop types, we expect that carbaryl and methomyl are commonly applied in the
Willamette Valley throughout the growing season. Existing stocks of carbofuran are also
expected to be applied throughout the growing season. Registered 24(c) uses in Oregon include
carbofuran application to potatoes, nursery stock, sugar beets, and watermelons. The Willamette
Basin is the largest agricultural area in Oregon. In 1992 the Willamette Basin accounted for 51%
of Oregon’s total gross farm sales and 58% of Oregon’s crop sales. About one-third of the
agricultural land is irrigated and most of it is adjacent to the mainstem Willamette River. Urban
developments are also located primarily in the valley along the mainstem Willamette River. We
expect carbaryl to be used throughout the year in urban and residential areas. Given that major
urban and agricultural areas are located adjacent to the mainstem Willamette, DPS exposure to
these pesticides is likely. We also expect that other AChE inhibiting pesticides will co-occur
with carbaryl, carbofuran, and methomyl in the waters of the Willamette Valley and exacerbate
adverse effects from AChE inhibition.
UWR steelhead enter the Willamette River in January and February and ascend to their spawning
areas in late March or April. After emergence, steelhead fry typically rear in off-channel habitats
associated with their natal rivers and streams for two to three years. Smolt migration past
Willamette Falls begins in early April and extends through early June, with peak migration in
early to mid-May. Most spend two years in the ocean before re-entering freshwater to spawn.
Much of the Willamette Valley has been converted to agricultural purposes. Based on the cooccurrence
of high use land classes with spawning and rearing habitats, we expect that the
proposed uses of the three carbamates may contaminate spawning and rearing habitats and lead
to both individual fitness and population-level effects. Therefore, the risk to this species’
survival and recovery from the stressors of the action is high for carbaryl, carbofuran, and
methomyl.
Summary of Species­Level Effects
In the preceding section NMFS described expected population-level effects in terms of
reductions in annual growth rate, productivity (reproduction), and abundance (numbers of
salmonids). We concluded that all but Ozette Lake sockeye salmon, Snake River sockeye
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