Purpose and Need

The purpose of the SEIS is to supplement the 2007 Interim Guidelines to modify guidelines for operation of Glen Canyon Dam and Hoover Dam to address historic drought, historically low reservoirs, and low runoff conditions in the Colorado River Basin. The need for the modified operating guidelines is based on the potential that continued low runoff conditions in the Colorado River Basin could lead Lake Powell and Lake Mead to decline to critically low elevations, impacting operations through the remainder of the interim period (prior to January 1, 2027).

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Alternatives

The draft SEIS considers three alternatives:

• The No Action Alternative, required by the National Environmental Policy Act, describes the continued implementation of existing agreements that control operations of Glen Canyon and Hoover Dams.
• Action Alternative 1 models operational changes to both Glen Canyon Dam and Hoover Dam. Action Alternative 1 includes assumptions for reduced releases from Glen Canyon Dam as well as assumptions for additional Lower Colorado River Basin shortages based on the concept of priority. Action Alternative 1 models progressively larger additional shortages as Lake Mead's elevation declines and models larger additional shortages in 2025-2026 as compared with 2024. The total shortages and Drought Contingency Plan contributions in 2024, as modeled, are limited to 2.083 million-acre-feet because this is the maximum volume analyzed in the 2007 Interim Guidelines final environmental impact statement.
• Action Alternative 2 is similar to Action Alternative 1, in how it models operational changes to both Glen Canyon Dam and Hoover Dam. Action Alternative 2 includes assumptions for reduced releases from Glen Canyon Dam as well as assumptions for additional Lower Colorado River Basin reductions that are distributed in the same percentage across all Lower Basin water users. While both the 2007 Interim Guidelines and the 2019 Drought Contingency Plan encompass shortages and contributions that reflect the priority system, the additional shortages identified in Action Alternative 2 for the remainder of the interim period would be distributed in the same percentage across all Lower Basin water users. Action Alternative 2 models progressively larger additional shortages as Lake Mead's elevation declines and models larger Lower Basin shortages in 2025-2026 as compared with 2024. The total shortages and Drought Contingency Plan contributions in 2024, as modeled, are limited to 2.083 million-acre-feet because this is the maximum volume analyzed in the 2007 Interim Guidelines FEIS.

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Public Involvement

The original May 30, 2023, deadline for the submission of comments on the draft SEIS is no longer in effect. Information on future public involvement opportunities will be posted when they are announced.

In May 2023, Reclamation held four virtual public meetings to provide information on the draft SEIS, answer questions, and take verbal comment. Each meeting presentation covered the same information. The question and answer and public comment portions of the meetings varied based on the public participants at each meeting.

The virtual public meeting presentation is available for review. La presentación de la reunión pública virtual está disponible en español.

• Draft Supplemental Environmental Impact Statement for Near-term Colorado River Operations
• Proyecto de Declaración de Impacto Ambiental Suplementaria para las Operaciones a Corto Plazo del Río Colorado

Before including your address, phone number, email address or other personal identifying information in any correspondence, you should be aware that your entire correspondence—including your personal identifying information—may be made publicly available at any time. While you may ask us in your correspondence to withhold your personal identifying information from public review, we cannot guarantee that we will be able to do so.

Questions

For further information, contact the project team by email at CRinterimops@usbr.gov or call the project telephone line at (602) 609-6739.