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S.11 DESCRIPTION OF ALTERNATIVES Under the No Action Alternative, Flaming Gorge Dam would be operated to achieve the flow and temperature regimes recommended by the 1992 Biological Opinion on the Operation of Flaming Gorge Dam. Depending upon the hydrologic conditions of the upper Green River Basin, forecasted flows on the Yampa River would be supplemented by releases from Flaming Gorge Dam designed to achieve the peak flow, duration, and base flow (riverflows not associated with snowmelt runoff) recommendations described in the 1992 Biological Opinion. Under the Action Alternative, Flaming Gorge Dam would be operated to achieve the flow and temperature regimes recommended in the 2000 Flow and Temperature Recommendations. SAM Development of Alternatives S.11.1.1 Criteria Used to Select Alternatives Potential alternatives analyzed in the DEIS were studied to determine whether they could meet the purpose of and need for the Proposed Action. A number of scenarios for dam operation, originally thought to be viable alternatives, were determined to be more accurately described as possible subsets of the Action Alternative. Because of the inherent need for operational flexibility in dam operations, as acknowledged by and incorporated into the 2000 Flow and Temperature Recommendations, and because any potential impacts from discreet operational scenarios are already captured by analysis of the Action and No Action Alternatives, it was determined that analyzing subtle differences in dam operations as separate alternatives would not yield meaningful information for the public or the decisionmaker. Alternatives that are included in this analysis are those which both: ? Meet flow and temperature recommendations as described in the 2000 Flow and Temperature Recommendations. ? Maintain all authorized purposes of the Flaming Gorge Unit of CRSP. S.11.1.2 Alternatives Considered but Eliminated From Detailed Study S.11.1.2.1 Modified Run of the River Alternative - During the scoping process, the National Park Service and others requested consideration of a Run of the River Alternative. Under such an alternative, dam releases would match the reservoir inflow (unregulated) to provide a more natural flow regime including more natural variations in the daily flows of the Green River below Flaming Gorge Dam. Further analysis of this alternative led to the establishment of a Modified Run of River Alternative, where dam releases equaled 87 percent (%) of the unregulated inflow to the reservoir. This provided reservoir operators the ability to store 13% of the spring inflow volume for release to meet project purposes and flow recommendations at other times of the year. The 87% level was chosen because it was the highest percentage that provided enough water S-14 -.% Operation of Flaming Gorge Dam Draft EIS