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~I . Mr. Lee J. McQui vey April 11, 1994 Page 4 1992 Act. The 2 proposed changes were designed to be made serially and observed in order to measure, if possible, any observable changes. We believe continuing the interim operating criteria while instituting these 2 changes as had previously been recommended is the wisest course of action that can be taken to protect resources downstream of Glen Canyon Dam, given the level of scientific research that has been done to date and the significant number of unanswered questions that remain about how these resources will respond to any significant change in the current operating criteria. " THE HABJ:TAT BUIlDING FIDW, HABITAT IlAINTEHANCB FIDW AND ENDANGERED SPECIES RESEARCH FLOWS ARE EXPERDmHTS, AND SHOUlD BE RECOGNIZED AS SUCH ... We note that the so-called beach building flow of some 45,000 cfs has been consigned to the adaptive management process for consideration before being implemented. We further understand that the scientists consider this to be an experiment and are now concerned about its duration and the effect of any such artificial flood on the downstream environment below Glen Canyon Dam. We ,certainly share that concern. .".' creating a clear-water artificial flood presents potential serious problems for aquatic and wildlife resources, while potentially benefiting only sediment deposition. Any such experiment would need to be very carefully constructed and methods for terminating it early in the face of significant adverse impacts would have to be developed. We also note that the Upper Colorado River commission has concluded that such an experiment would violate the "Law of the River" and would require Congressional authorization. ... .'. .-, t~.. .~.~ The habitat maintenance flow is also an artificial clear-water flood in which a wall of water at least lO, 000 . cubic feet per second greater .than the Canyon was experiencing at the time would be deliberately forced down the Canyon. It is ironic that the critics of the fluctuating flow regime of Glen Canyon Dam have described the daily fluctuations as flows "flushing the Grand Canyon. " Yet we are now faced with a common element for all alternatives for future operations of the Dam being several levels of artificially created floods that surely will have more significant adverse impacts on downstream resources than the fluctuating flow regime could ever produce. The third common element of the preferred alternative carries with it the same potential adverse consequences. High steady flows in .'