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

to as connectivity (PNERC 2002). As river height increases with heavier flows, more
side channels form and connectivity increases.
Healthy riparian habitat and floodplain connectivity are vital for supporting a salmonid
population. Once the area has been disturbed, it can take decades to recover (Smith
2005). Consequently, most land use practices cause some degree of impairment.
Development leads to construction of levees and dikes, which isolate the mainstem river
from the floodplain. Agricultural development and grazing in riparian areas also
significantly change the landscape. Riparian areas managed for logging, or logged in the
past, are often impaired by a change in species composition. Most areas in the northwest
were historically dominated by conifers. Logging results in recruitment of deciduous
trees, decreasing the quality of LWD in the rivers. Deciduous trees have smaller
diameters than conifers; they decompose faster and are more likely to be displaced
(Smith 2005).
Without a properly functioning riparian zone, salmonids contend with a number of
limiting factors. They face reductions in quantity and quality of both off-channel and
pool habitats. Also, when seasonal flows are not moderated, both higher and lower flow
conditions exist. Higher flows can displace fish and destroy redds, while lower flows cut
off access to parts of their habitat. Finally, decreased vegetation limits the available
shade and cover, exposing individuals to higher temperatures and increased predation.
Geographic Regions
For a more fine scale analysis, we divided the action area into geographic regions: the
Southwest Coast Region (California) and the Pacific Northwest Region (Idaho, Oregon,
and Washington). The Pacific Northwest Region was further subdivided according to
ecoregions or other natural features important to NMFS trust resources. Use of these
geographic regions is consistent with previous NMFS consultations conducted at the
national level (NMFS 2007). We summarize the principal anthropogenic factors
occurring in the environment that influence the current status of listed species within each
region. Table 29 provides a breakdown of these regions and includes the USGS
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