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c' t Summary of Public Comments re: NPS Proposed Black Canyon Water Right Quantification .j e PEAK FLOWS I, Too big - results in downstream flooding. . commercial and residential properties. agricultur~llands and related water structures. city property, highways and bridges. waste water tre'llment plant may be threatened. . will NPS accept responsibility? . how is BR involved? Will there be continued coordinated effort with BR to regulate Aspinall releases during emergencies? Can NPS force BR to increase flood flows? . timing ofNPS pe:lk flow? When? To coincide \\~th the North Fork pe:Ik? Aspinall Unit spills can result in an uncontrolled downstream environment which: . could jeopardize public safety . may be detrimental to young-of-the-year trout fry How will dam safety and the safety of downstream property and residents be insured? Who will bear the cost of increased operation and maintenance expenses associated with wear and tear on spillways? Operation of the Aspinall Unit should be optimized to prevent spills and take advantage of power generation revenue. . Flows in excess of 12,500 cubic feet per second (cfs) could cause severe damage to the Uncompahgre Valley Water Users Association diversion dam at the East Portal of the Gunnison TunneL e Proposed peak flow releases when coupled with rainstonn-driven flash floods cause unnecess:lry downstream flooding. 2. Too smaIl. . NPS recom!nenced flows are ~considernbly short of what studies have shown are needed for sufficient sediment trnnsport." High-flow targets must be OCc:lSionally higher. . Average annual peak flow target should be closer to the historic average of 12,000 cfs, and adjusted from there based on annual water'supply forecast. 3. "FLUSHING" flows. . debris and sediment being flushed from the canyon... ~debris that has been there since 1931" - what impact is this going to have on downstream environment and infrastructure? 4, NPS pe:Ik flow requests are vague and based on future, continuing negotiations, not a firm commitment to a specific flow regime, NPS should develop binding criteria for releases based on different snowpack and runoff scenarios; criteria should include duration. ramping rates, shoulder flows. These criteria should be released for public comment. Ai least for "wet", "normal", and "dry" years, with and without full consumption of 240,000 acre-feet from the Aspinall Unit. GENERAL HYDROLOGY L Why is the NPS using pre-tunnel hydrology as basis for baseflow requirements and post-tunnel for peak flow tcquiremcnts? Exercise caution when referencing 1933 conditions, they do not necessarily represent "natur~l" conditions, but possibly a tr.msitory condition in a dynamic system. e