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Table II), and the date of the yearly peak flow is thus determined by the date of the high flow in the 15-mile reach. Flows at the top of the 15- mile reach comprise an average of 37.2% in April, 54.98 in May, and 65.48 in June of flows at the USGS gage near the Colorado/Utah State line (Table 5). When the return flows from upstream irrigation removal are added back throughout the length of the Grand Valley, flows from the upper Colorado drainage are calculated to comprise 53.38, 63.38, and 74.3% of State line flows during April, May, and June, respectively. During historic times, before major upstream dams and transmountain diversions were in place, the relative contributions of the two rivers were not substantially different from their relative contributions today (Table 5 and Fig. 9). To provide peak flows of 30,000 to 40,000 cfs at the State line, the flow of the Colorado River near Cameo, including the contribution of Plateau Creek just downstream, needs to be approximately 21,000 to 26,000 cfs and ap- proximately 19,500 to 25,000 cfs in the upper end of the 15-mile reach (Table 6). However, this assumes that the average input from the Gunnison River and the amount removed for and returned from local irrigation remain at current levels. To maintain the status quo, these flows will have to occur at a frequency averaging one in four years. To improve Colorado squawfish reproduction downstream, and ultimately increase the chances for species recovery, the frequency of peak flows of this magnitude will need to be increased. Thus, we believe that high spring flows from the Colorado River drainage upstream from the mouth of the Gunnison River are necessary to create and maintain habitat for adult Colorado squawfish both within the 15-mile reach and in the important reaches of the Colorado River downstream. These high flows not only create the diversity of habitat seemingly required by 33