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

have greatly reduced or eliminated in-stream flows during spring-run migration periods.
Problems in the migration corridor include unscreened or inadequately screened water
diversions, predation by nonnative species, and excessively high water temperatures.
Collectively, these factors have impacted spring-run Chinook salmon critical habitat and
population numbers (CDFG 1998). Several actions have been taken to improve and
increase the PCEs of critical habitat for spring-run Chinook salmon, including improved
management of CV water (e.g., through use of CALFED EWA and CV Project
Improvement Act (b)(2) water accounts), implementing new and improved screen and
ladder designs at major water diversions along the mainstem Sacramento River and
tributaries, removal of several small dams on important spring-run Chinook salmon
spawning streams, and changes in ocean and inland fishing regulations to minimize
harvest.
Lower Columbia River Chinook Salmon
Distribution
Lower Columbia River (LCR) Chinook salmon includes all naturally-spawned
populations of Chinook salmon from the Columbia River and its tributaries from its
mouth at the Pacific Ocean upstream to a transitional point between Oregon and
Washington, east of the Hood River and the White Salmon River (Figure 7). Naturally
spawned populations also occur along the Willamette River to Willamette Falls, Oregon,
exclusive of spring-run Chinook salmon in the Clackamas River (Table 5). The Cowlitz,
Kalama, Lewis, White Salmon, and Klickitat Rivers are the major river systems on the
Washington side, and the lower Willamette and Sandy Rivers are foremost on the Oregon
side. The eastern boundary for this species occurs at Celilo Falls, which corresponds to
the edge of the drier Columbia Basin Ecosystem. Historically, Celilo Falls may have
been a barrier to salmon migration at certain times of the year. Table 8 identifies
populations within the LCR Chinook salmon ESU, their abundances, and hatchery input
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