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

life history groups: one where the juveniles rear for one or two years mainly in freshwater and
another where the juveniles rear at the upper end of coastal lagoons for the first or second
summer.
In conclusion, based on the long freshwater residence time of steelhead and the considerable
overlap between S-CCC steelhead distribution and expected pesticide use, we expect that the S-
CCC may experience high levels of exposure. We expect that proposed uses of the three
carbamates that contaminate spawning and rearing habitats may lead to both individual fitness
and population-level consequences. Therefore, the risk to the survival and recovery of S-CCC
from the proposed action is high for carbaryl, carbofuran, and methomyl.
Southern California Steelhead
The SC steelhead DPS includes populations in five major and several small coastal river basins
in California from the Santa Maria River to the U.S. – Mexican border. It is estimated that the
species’ current distribution constitutes about 1% of the historical distribution. Current
abundance is considerably reduced with an estimated escapement of 500 fish for four of the
larger rivers. Long-term estimates and population trends are lacking for the streams within the
DPS.
The major threats to this DPS identified in the Status of Listed Resources and Environmental
Baseline sections are dams and other migration barriers, urbanization and channel modification,
agricultural activities, and wildfires. As a result of these activities, the stream substrate contains
a high proportion of fines, stream channels lack complexity, banks are eroding, migration
barriers restrict fish access to cooler head waters and tributaries, and the water is turbid and
contaminated.
Agriculture is concentrated in low laying areas and floodplains along the estuaries and lower
reaches of streams. Carbaryl, carbofuran, and methomyl are expected to be commonly used for
several crops during the growing season. Large areas of dense development exist in the counties
of Santa Barbra to San Diego. Carbaryl is expected to be used within urban/residential areas
throughout the entire year. The NAWQA analysis detected more than 58 pesticides in ground
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