Colorado River Operations: Draft Supplemental EIS.pdf

The U.S. Department of the Interior's Bureau of Reclamation is proposing to revise the 2007 Interim Guidelines for Glen Canyon and Hoover Dams' operations, starting in 2024, due to potential low-runoff conditions in the Colorado River Basin. The draft Supplemental Environmental Impact Statement (SEIS) for Near-term Colorado River Operations outlines this action.

Proposed Action:
- Revise operating guidelines for Glen Canyon and Hoover Dams to mitigate risks from continued low runoff.

Lead Agency:
- Bureau of Reclamation, Upper Colorado Basin Interior Region 7 and Lower Colorado Basin Interior Region 8

Cooperating Agencies:
- Bureau of Indian Affairs, National Park Service, Western Area Power Administration, US Fish and Wildlife Service, US Section of the International Boundary and Water Commission

Alternatives Considered:
1. No Action Alternative: Maintain current guidelines, implementing shortage guidelines, coordinated reservoir operations, and drought contingency plans.
2. Action Alternative 1: Revise guidelines to prioritize Lake Powell's elevation, with specific targets and operations.
3. Action Alternative 2: Revise guidelines to prioritize Lake Mead's elevation, with different targets and operations.

Eliminated Alternatives:
- Fill Lake Powell/Lake Mead first, decommission Glen Canyon Dam, one-dam alternative, evaporation/seepage reduction, ecosystem-based alternative, worst-case drought alternative, hydropower prioritization, and water importation.

Potential Effects:
- Impacts on water supply, hydropower, recreation, Native American interests, and environmental resources (e.g., fish, wildlife, and vegetation) will be analyzed in detail in the SEIS.