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

60 miles downstream from the dam. As a result the ESU has been reduced to a single
spawning population confined to the mainstem Sacramento River below Keswick Dam.
Some adult winter-run Chinook salmon were recently observed in Battle Creek, a
tributary to the upper Sacramento River.
Quantitative estimates of run-size are not available for the period before 1996, the
completion of Red Bluff Diversion Dam. However, winter-runs may have been as large
as 200,000 fish based upon commercial fishery records from the 1870s (Brown, Moyle et
al. 1994).
The CDFG estimated spawning escapement of Sacramento River winter-run Chinook
salmon at 61,300 (60,000 mainstem, 1,000 Battle Creek, and 300 in Mill Creek) in the
early 1960s. During the first three years of operation of the county facility at the Red
Bluff Diversion Dam (1967 to 1969), the spawning run of winter-run Chinook salmon
averaged 86,500 fish. From 1967 through the mid-1990s, the population declined at an
average rate of 18% per year, or roughly 50% per generation. The population reached
critically low levels during the drought of 1987 to 1992. The three-year average run size
for the period of 1989 to 1991 was 388 fish.
Based on the Red Bluff Diversion Dam counts, the population has been growing rapidly
since the 1990s. Mean run size from 1995-2000 has been 2,191, but have ranged from
364 to 65,683 (Good, Waples et al. 2005). Most recent estimates indicate that the shortterm
trend is 0.26, and the population growth rate is less than one.
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