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quantify a reserved water right for the Black Canyon of the Gunnison National Park located downstream from the Aspinall Unit). Alternative operation modes, ranging from placing limitations on bypasses to fully using all of the Aspinall Unit bypasses and spillways, were analyzed to see to what degree the t10w recommendations could be met. Model runs assume the draft t10w recommendations have priority over storage and release of Aspinall Unit water. Modeling the recommendations as a priority illustrates impacts of meeting recommended t1ows. The Aspinall Unit is not a project in the traditional sense of other Reclamation projects where all project storage water is dedicated solely to specific uses such irrigation. Storage water used in modeling t10w recommendations is not currently allocated to a specific use. In addition, the Colorado River Storage Project has no traditional water user repayment entity, however, CRSP has fish and wildlife uses included in its legislative authorization. Legislation authorized the Unit to be built for a variety of uses, including the development of Colorado's compact entitlement and fish and wildlife purposes. Previous biological opinions on the Dolores and Dallas Creek projects depend on operation of the Aspinall Unit to offset their depletion impacts to the Colorado River up to 148,000 acre-feet. Reclamation modeled a combination of natural t10ws and releases of Aspinall Unit storage to assist in meeting the draft t10w recommendations. The measuring point to determine if t10w recommendations are met is the Gunnison River gage near Grand Junction, Colorado (Whitewater gage). This gage is located 80 miles downstream from Crystal Dam-the furthest downstream of the Aspinall Unitdams. Significant tributaries such as the North Fork of the Gunnison and the Uncompahgre rivers enter the Gunnison between Crystal and the Whitewater gage. Model runs attempt to meet t10w recommendations using a combination of Aspinall Unit releases and downstream tributary int1ow, Another measuring point is the Gunnison River gage downstream from the Redlands Diversion Dam. This gage is located approximately 2 miles upstream from the cont1uence with the Colorado River. The model is not a water rights model; therefore, it does not evaluate the existing and future water rights on the Gunnison River. This report does not analyze effects ofNPS reserved right proposed flows; however, there is a section which compares NPS proposed flows and draft fish flow recommendations to give an overview of potential similarities and differences. The model results show that draft t10w recommendations can only partially be met under current Aspinall Unit operating criteria and outlet capacities. Under the baseline run, the draft fish flow recommendation peaks could be met approximately 19 percent of the time; with model runs intended to meet the desired peaks, this could be increased to 50-58 percent of the time2. The reason the model did not meet the recommended peaks more is the difficulty in matching the timing of downstream tributary peaks. This would continue to be an 2F or purposes of this report, peaks are assumed met if 90 percent of a peak flow is reached. 1ll