Aspinall EIS - Scoping Report May 2007

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describe the annual and seasonal patterns of flow in the lower Gunnison River , and in the Colorado River downstream from their confluence , identified as needed to help recover endangered fish. The initial definition of the proposed action is to : develop operating guidance to implement reservoir operation changes to avoid jeopardy to endangered species while maintaining the congressionally authorized purposes of the Unit. The need for the proposed action is defined as follows: Guidance is needed to o perate the Unit to avoid jeopardy to endangered fish species while comply ing with the Unit’s authorized purposes. The need sets the overall focus of the EIS process and is the ultimate requirement that all alternatives must satisfy. The underlying need associated with the proposed action is based on legal obligations to maint ain the authorized purposes of the Aspinall Unit as well as to comply with the ESA. There are a group of purposes and desired goals that will be addressed in alternatives. The following purposes and /or goals of the proposed actions are recognized: ? Help the state of Colorado protect/use its compact entitlement ? Operate alternatives within State water law ? Satisfy as many needs as possible with same water releases ? Protect recreation at Unit reservoirs and in the Gunnison Gorge and Lower Gunnison River ? Protec t tailwater and reservoir fisheries ? Provide needed hydropower flexibility ? Provide flood control ? Provide for public input and public information concerning operations of the Unit ? Assist the National Park Service in protecting resources of the Black Canyon o f the Gunnison National Park (Black Canyon) ? Allow for adaptive management as new scientific data becomes available through monitoring of endangered fish responses The degree to which alternatives meet identified purposes provides decision makers guidance in selecting alternatives for detailed study and ultimately for selection of a recommended plan . Primary water storage at the Unit oc curs in the uppermost and largest reservoir, Blue Mesa. Reclamation manages available water at the Unit within certain si deboards that include annual snowpack conditions, senior water rights, minimum downstream flow requirements, flood control, powerplant and outlet capacities, reservoir elevation goals, fishery management recommendations, dam safety considerations, and othe rs. Certain sideboards can be considered mandates such as honoring senior water rights and flood control, while others such as reservoir elevation criteria to reduce landslides are given a high priority. To conserve water for later use, an operational go al is to fill Blue Mesa by the end of July. Another operational goal is to draw Blue Mesa down to an elevation of 3