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CONCLUSIONS 26 4 CONCLUSIONS The NRC Committee on Endangered and Threatened Fishes in the Klamath River Basin has studied the USBR biological assessment on the shortnose and Lost River suckers, the USFWS biological opinion with its reasonable and prudent alternative (RPA) on these same species, and supporting documentation. The committee also has heard oral presentations and open public comment on the issues related to these endangered fishes in the Klamath River Basin. The committee finds strong scientific support for the requirements of the RPA except for the requirement for specified minimum lake levels in Upper Klamath Lake. Extensive field data on the fish and environmental conditions in Upper Klamath Lake do not provide scientific support for the underlying premise of the RPA that higher lake levels will help maintain or lead to the recovery of these two species. At the same time, operation of Upper Klamath Lake at mean minimum levels below the recent historical levels (1990â 2000), as could occur through implementation of the USBR assessment, would pose unknown risks, because these conditions have not been observed over the last 10 years, the interval over which good environmental documentation is available. The present scientific record is consistent with use of operational principles in effect between 1990 and 2000. The NRC committee has studied the USBR biological assessment on the Southern Oregon/Northern California Coasts evolutionary significant unit of the coho salmon in the Klamath River Basin and the accompanying biological opinion prepared by NMFS, its RPA requirements, and supporting documentation. The committee also heard oral presentations of scientists contributing
CONCLUSIONS 27 to research on this issue and open public testimony. The RPA contains requirements for minimum flows in the Klamath River below Iron Gate Dam, limitations on ramping rate below Iron Gate Dam, and interagency coordination. The committee finds reasonable scientific support for the suppression of ramping rates as given in the RPA and for coordination. The committee does not find scientific support for the proposed minimum flows as a means of enhancing the maintenance and recovery of the coho population. The proposal of USBR, however, as given in its biological assessment, could result in more extreme suppression of flows than has been seen in the past and cannot be justified. On the whole, there is no convincing scientific justification at present for deviating from flows derived from operational practices in place between 1990 and 2000. The conclusions of the NRC committee as presented above apply to interim management of the Klamath Project. The committee will make a separate analysis of the scientific evidence, including any new evidence, supporting various actions that might result in improvements in stocks of endangered suckers and coho salmon in the Klamath River Basin over the long term.