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

density residential with some agricultural activity). Pesticides are regularly applied to
agricultural and non-agricultural lands and are found virtually in every land use area.
Pesticides and other contaminants drain into ditches in agricultural areas and eventually
to stream systems. Roads bring surface water runoff to stream systems from industrial,
residential, and landscaped areas in the urban environment. Pesticides are also typically
found in the right-of-ways of infrastructure that connect the major landscape types.
Right-of-ways are associated with roads, railways, utility lines, and pipelines.
In the 1930s, all of western Washington contained about 15.5 million acres of
“harvestable” forestland. By 2004, the total acreage was nearly half that originally
surveyed (PSAT 2007). Forest cover in Puget Sound alone was about 5.4 million acres in
the early 1990s. About a decade later, the region had lost another 200,000 acres of forest
cover with some watersheds losing more than half the total forested acreage. The most
intensive loss of forest cover occurred in the Urban Growth Boundary, which
encompasses specific parts of the Puget Lowland. In this area, forest cover declined by
11% between 1991 and 1999 (Ruckelshaus and McClure 2007). Projected land cover
changes indicate that trends are likely to continue over the next several decades with
population changes (Ruckelshaus and McClure 2007). Coniferous forests are also
projected to decline at an alarming rate as urban uses increase.
According to the 2001 State of the Sound report (PSAT 2007), impervious surfaces
covered 3.3% of the region, with 7.3% of lowland areas (below 1,000 ft elevation)
covered by impervious surfaces. From 1991 to 2001, the amount of impervious surfaces
increased 10.4% region wide. Consequently, changes in rainfall delivery to streams alter
stream flow regimes. Peak flows are increased and subsequent base flows are decreased
and alter in-stream habitat. Stream channels are widened and deepened and riparian
vegetation is typically removed which can cause increases in water temperature and will
reduce the amounts of woody debris and organic matter to the stream system.
Pollutants carried into streams from urban runoff include pesticides, heavy metals, PCBs,
polybrominated diphenyl ethers (PBDEs) compounds, PAHs, nutrients (phosphorus and
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