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I I I il I I a I I I I I I I I I I I I fish in some years. An end product of rhat study was to produce a process to coordinate operations of parricipating reservoirs on an annual basis to achieve this peak flow enhancement. In a combined effort to contribute to the recovery program, a Coordinated Reservoir Operations team, which included the Division of Water Resources as well as major reservoir owne rs/operators and other water management entities, was fonned to develop a program to enhance peak river flows. Coordinated reservoir releases were made from Ruedi, Williams Fork, Green Mountain, and Wolford Mountain Reservoirs this year beginning on May 30th and continuing through June 5th. The chart on the next page shows graphically the effect of these combined reservoir releases on the flows of the Colorado River at the Cameo gage. The goal was to increase the spring flows as much as possible without exceeding the National Weather Service flood level of 26,600 cfs, and this goal was successfully accomplished. The US Fish and Wildlife Service and the Division 5 Engineer were charged with the responsibility to detennine when it was appropriate to begin and end the releases, detennine the amount of the releases, and to notify participants accordingly. The Division 5 Engineer was required to conduct an accounting of releases and provide a record of releases during the specified time period. Coordinated Reservoir Operations are expected to continue annually until the endangered fish are fully recovered. " VIII. Fish & Wildlife Service Monitoring Recent biological and geomorphology studies have documented changes in physical processes and native fish populations related to the modification of the natural snowmelt hydrograph due to the construction of reservoirs upstream of the Colorado- Utah State line. These changes have reduced the ability of the Colorado River to move sediment and rework the river channel (pitlick 1999). It is generally accepted that these reservoirs have altered stream flows of the Colorado River and have caused changes in the amount, diversity and quantity of habitat used by the endangered Colorado River fish. In compliance with the Recovery Program RIPRAP, monitoring of embeddedness of gravel and cobble substrates in the upper Colorado River was initiated. Twelve measurements were taken at each of IS sites (eight in the IS-mile reach; seven in the 18-mile reach - which is the stretch of the Colorado River, 18 miles downstream from the Gunnison River) on seven dates in 1996 (three during runoff; four during baseflow) and five dates in 1997 (three during runoff, two during baseflow). Rock sizes were generally larger lower in the channel at base flow elevations than higher in the channel margin inundated during runoff. Additionally, average rock size was slightly larger in the 18-mile reach than in the IS-mile reach, but only at base flow locations. Spring runoff flows in both the IS- and] 8-mile reaches were sufficient in both years to mobilize the bed in many areas. In addition, runoff flows during 1995 (prior to sampling) produced widespread mobilization of the bed. Average rock sizes changed significantly between 1996 and 1997 at several of the sampling sites. Mean depth to embeddedness (distance from the top of rocks in the surface layer down to the point where rocks are embedded in fine sediment) ranged from 80 to 171 mm; the adjusted mean of the samples was 125 mm in 1996 and 123 mm in 1997. The mean number 'free rocks' (those making up the layer above the level of embeddedness) ranged from 1.1 to 4.3; the adjusted mean was 1.9 rocks in both years. Riffles had slightly greater depths to embeddedness than did runs. For other comparisons, depths to embeddedness were found to be similar between 15- and 18- mile reaches, between 1996 and 1997, and ]4