amounts of locally derived cool water with much larger amounts of warm water from points upstream.
Progressive depletion of flows in the Klamath River main stem would at some point be detrimental to coho salmon through stranding or predation losses. Thus, incremental depletions beyond those reflected in the recent historical record could be accomplished only with increased risk to coho salmon. At the same time, the available information provides little support for benefits presumed to occur through the increase of flows beyond those of the past decade. While single-year or multiple-year averages of low-flow extremes beyond those presently reflected in the record cannot be supported, there also is presently little evidence of a scientific nature that increased low flows will improve the welfare of the coho salmon.
Modeling of temperature and habitat might be useful, but convincing evidence of a relation between the welfare of the coho and environmental conditions must be drawn to some extent from direct observation. For example, when related to specific flow conditions, year of class strength, abundance of various life history stages, or other biological indicators of success would greatly improve the utility of modeling and other information. The small size and scattered nature of the present native coho population makes collection of such data difficult, however.
The RPA requirements related to ramping rates and interagency coordination seem supportable. Given direct field observation of the stranding of coho at the current ramping rates (NMFS 2001) and the mortality that is implicit in these observations, reduction in ramping rates seems a reasonable and prudent measure for protection of coho. Coordination, a final requirement of the RPA, is an obvious necessity because of the need to optimize use of water for multiple purposes.