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<br />-28- <br /> <br />The data in Table 14 is a comparison of the average density and biomass <br />estimates for the Dolores River (1986-1991) with similar averages for four <br />other tailrace fisheries in Colorado. All four rivers included in the <br />comparison were under restrictive angling regulations but not necessarily <br />catch and release angling only. The Dolores River is the only stream in Table <br />14 where catch and release angling was in effect for all years for which data <br />was included. <br /> <br />The data in Table 14 demonstrates the average density and biomass statistics <br />for the Gunnison, Fryingpan, Blue, and South Platte rivers are 8 to 16 times <br />greater than the same statistic for the Dolores River. All of the streams <br />except the South Platte are below USBOR impoundments. All of these streams <br />suffer major depletions upstream of the study sections and/or above the <br />impoundments controlling the delivery to the downstream fishery. The Dolores <br />Project is not unique in the amount of water diverted for irrigation and/or <br />other purposes, but is atypical (for a federal water project) for the amount <br />of water al10cated to the downstream fishery. <br /> <br />Dolores River Flows and Water Temperatures <br /> <br />Dolores River Flows - All of the foregoing information, including the original <br />report (Nehring 1991), provides insights into what has happened to the Dolores <br />River trout population in the 5-year period between 1986 and October 1991. <br />The bottom line, however, is "how much water is necessary to maintain a <br />quality trout fishery in this river from the McPhee Dam to Bradfield Bridge"? <br /> <br />Table 15. Summary of the inflow to McPhee Reservoir and outflow to the <br />Dolores River versus trout density and biomass responses, 1984- <br />1991. <br /> <br /> AF"/Water Year X 1000 Max. Outflow Trout Population <br />Water Winterb <br />Year Inflow Outflow VoL C (% Inflow Density Biomass <br />1984 580.3 408.7 -.. -... -.. ...... - 70.4 Increase Increase <br />1985 611. 0 380.7 60.9 ...... .. 62.3 Increase Increase <br />1986 572.3 304.9 21. 3 ...... .. 53.3 Increase Increase <br />1987 589.2 398.8 80.8 99.3 67.7 Increase Increase <br />1988 259.2 104.6 28.3 99.6 40.4 Increase Increase <br />1989 263.1 115.3 28.5 100.3 43.8 Increase Increase <br />1990 142.5 37.7 24.9 81.3 26.5 Decrease Decrease <br />1991 293.0 50.8 11.3 96.7 17.3 Decrease Decrease <br /> <br />" Acre-feet <br />b October 1 - March 31 <br />C Percentage of maximum pool volume attained during that water year. <br />