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New Findings Cast Doubt on CDFG Fish Die-Off Assessment

April 2003

Recent findings incorporated into a declaration submitted in an upcoming court case suggest that a report released earlier this year by the California Department of Fish and Game (CDFG) contains “several major errors”. David Vogel, a fisheries biologist with 28 years experience, recently submitted information to an Oakland judge that raises serious questions about the CDFG report, which has been hailed by environmental activists as proof that Klamath Project operations were responsible for the death of 33,000 salmon in the lower Klamath River last fall. The California Resources Agency concluded within days of the fish die-off that operation of the Klamath Project, located 200 miles upstream of the die-off, was somehow to blame. A report released by CDFG two months later reaches the same conclusion. According to Vogel, CDFG’s report contains several major errors:

CDFG inappropriately uses monthly average air temperatures and monthly average water temperatures to derive conclusions on potential cause and effects on the fish die-off. The use of monthly averages can mask important daily changes in temperatures stressful to fish.

 CDFG incorrectly plotted water temperature data collected in the area of the fish die-off; CDFG mistakenly plotted water temperature data in the lower river skewed four days earlier than when the data were actually collected. The significance of this is that CDFG’s report misrepresented important water temperature data collected just prior to and during the period of the fish die-off.

 CDFG fails to explain the relationship between cooling water temperatures and the peak run of salmon that occurred in late August in the lower river. Yurok Tribe biologists noted a pronounced, and uncharacteristic, cooling trend in the lower river occurred in late August. According to the CDFG fish die-off report, an early, uncharacteristic peak run of salmon occurred concurrently in the lower river. Those data suggest that large numbers of salmon likely entered the lower river earlier than usual in response to the sudden cooling trend. However, a pronounced warming trend followed which exposed the undoubtedly crowded fish that had already entered the river to stressful conditions. By the second week in September 2002, a precipitous decline in water temperatures occurred that likely prompted even more fish to enter the lower river.

 CDFG’s speculation concerning a physical fish passage barrier in the lower Klamath River is not supported because: 1) fish passage occurred in other years with similar or less flow; and 2) data in the CDFG report demonstrates fish passage occurred during the flow conditions present prior to the fish die-off.

Of note, CDFG asserts that toxic substances could not have caused the fish die-off, even though it admits that water samples were not taken until 7 days after the onset of the fish die-off. Therefore, that potential source of mortality is still in question. To date, Vogel is unaware of any evidence ruling out the possibility that toxic substances may have caused the fish die-off.

Myth vs. Fact: 2002 Fish Die-Off

KWUA questions arguments made by environmental advocates and tribal biologists because they do not articulate how increased releases from Iron Gate Dam (IGD) could have prevented the 2002 Klamath River fish die-off more than 170 river miles downstream of the dam. If the primary cause of the fish die-off was warm water, it was physically impossible for IGD to cool the river down to tolerable levels for salmon.

MYTH: Increased IGD releases in the upper river could have ameliorated water temperatures in the lower river.
FACT: Maximum water temperatures in the upper Klamath River were much higher than the lower river just prior to the fish die-off and very similar during the time of the fish die-off.

MYTH: Increasing upper Klamath reservoir releases during late summer or early fall during naturally dry hydrologic conditions, such as occurred in September 2002, would benefit salmon.
FACT: Due to a variety of meteorological, physical, and biological reasons, artificially increasing flows at that time would probably be harmful. This is because IGD discharges are too warm for salmon during much of September.

MYTH: Additional Klamath Project flows released from Iron Gate Dam in early September 2002 would have prevented the fish die-off.
FACT: There is no evidence that releasing more water from IGD during early or mid-September could have prevented a fish die-off more than 170 river miles downstream because upper main stem temperatures were within the range known to cause mortality or reproductive failure in salmon. The gradual declining temperatures in the Klamath River downstream of IGD during the fall are primarily attributable to normal seasonal declines in ambient air temperatures, not river flow.

MYTH: 2002 was unique because there was a large salmon run and low Iron Gate Dam flows, which explains the fish die-off in September 2002.
FACT: Contrary to this claim, 1988 had a much larger salmon run than 2002 and the lower Klamath River flows were similar to that observed in 2002. According to the CDFG fish die-off report, in 1988 the lower Klamath River flow during September was 2,130 cfs, the salmon run was 215,322 fish and there was no consequent fish die-off; in 2002, the lower Klamath River flow during September was 2,129 cfs and the salmon run was 132,600 fish. These facts provide empirical evidence that this assumption is invalid.


Dan Keppen
Former Executive Director Klamath Water Users Association





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