Glen Canyon Dam
Adaptive Management Program

The Glen Canyon Dam Adaptive Management Program was developed to provide an organization and process for cooperative integration of dam operations, downstream resource protection and management, and monitoring and research information, as well as to improve the values for which the Glen Canyon National Recreation Area and Grand Canyon National Park were established.

Adaptive management is a dynamic process where people of many talents and disciplines come together to make the right decision in the best interests of the resources.

Current Focus

Cool Mix Flows Underway

The Bureau of Reclamation has started releasing colder water from the depths of Lake Powell through Glen Canyon Dam to disrupt the establishment of smallmouth bass, which pose a threat to populations of the federally protected humpback chub below the dam.

The 'cool mix' alternative, which is the preferred alternative in the final environmental impact statement and Record of Decision, consists of releasing water from both the penstocks and river outlet works. The intakes for the river outlet works are located approximately 100 feet below those for the penstocks and can release cooler water downstream. The minimum amount of water needed will be released through the river outlets to meet the water temperature objective.

Read the full press release here

Record of Decision - Glen Canyon Dam/Smallmouth Bass Future Flow Options and High-Flow Experimental Protocol

Reclamation has finalized it National Environmental Policy Act analysis of flows from Glen Canyon Dam to protect the humpback chub and other native fish species with the signing of a Record of Decision for the Glen Canyon Dam Long-Term Experimental and Management Plan (LTEMP) Final Supplemental Environmental Impact Statement (SEIS) Link is to a PDF file. The LTEMP SEIS supplements the 2016 LTEMP Final Environmental Impact Statement (FEIS) and Record of Decision Link is to a PDF file and analyzes various flow options from Glen Canyon Dam to help disrupt the establishment of nonnative fish, primarily smallmouth bass, below the dam in the Colorado River.

Reclamation is also making adjustments to the high flow experiment (HFE) sediment accounting period and implementation window. These changes adjust the semiannual sediment accounting period to an annual period, with the option to implement a spring or fall HFE release, or both.

Preferred Alternative

For 2024, Reclamation selected the Cool Mix Alternative, identified in the Final SEIS as both the preferred alternative and the environmentally preferred alternative. For potential flow-based actions to address smallmouth bass after 2024 (if warranted based on temperature targets), Reclamation will consider the Cool Mix Alternative along with the other action alternatives described in the 2024 LTEMP SEIS, and will make implementation decisions from 2025 to 2027 based on future actual conditions.

Additional Resources


For further information, contact the project manager by email at: for more information.

Program Background

Colorado River at Lees Ferry
Colorado River at Lees Ferry

Since Glen Canyon Dam was completed in 1963, increasing concern was expressed by the public and federal and state agencies regarding how dam operations may be adversely affecting the downstream environment. To begin addressing these growing concerns, in December 1982, the Bureau of Reclamation initiated the multi-agency interdisciplinary Glen Canyon Dam Environmental Studies at the direction of the Secretary of the Interior.

In November 1989, the Secretary directed an Environmental Impact Statement be prepared on the operation of Glen Canyon Dam, and the Secretary designated Reclamation as the lead agency. This Final EIS, completed in March 1995, received broad and intense interest from water and power users, environmental and conservation groups, Federal and State agencies, Indian tribes, and private citizens across the country.

Findings from the EIS indicated that many uncertainties still exist regarding the downstream impact of water releases from Glen Canyon Dam. The EIS team consolidated the issues of public concern, identifying the significant resources and associated issues to be analyzed in detail. These resources include: water, sediment, fish, vegetation, wildlife and habitat, endangered and other special status species, cultural resources, air quality, recreation, hydropower, and non-use value.

In compliance with the Grand Canyon Protection Act of 1992 (Public Law 102-575), the EIS proposed a process of "adaptive management" whereby the effects of dam operations on downstream resources would be monitored and assessed.

The Act, and the EIS are the guiding documents for development of the Adaptive Management Program. The program meets the purpose and strengthens the intent for which the EIS was prepared, and ensures the primary mandate of the Act is met through future advances in information and resource management.

Section 1802 of the Act directed the Secretary to establish and implement long-term monitoring programs and activities to ensure the Glen Canyon Dam is operated "... in such a manner as to protect, mitigate adverse impacts to, and improve the values for which Grand Canyon National Park and Glen Canyon National Recreation Area were established, including, but not limited to natural and cultural resources and visitor use."

In order to comply with the consultation requirement of the Act, Section 1805 of the Act, the EIS recommended formation of a federal advisory committee. The Transition Work Group was formed to operate until such time as a federal advisory committee could be formed, and a Record of Decision signed by the Secretary of the Interior to initiate a process of "management" (operating criteria for unbiased scientific research and data collection) whereby the effects of dam operations on downstream resources would be assessed. Meetings were held with representatives from the cooperating agencies and public interest groups who provided comments on the criteria for development of reasonable alternatives for the EIS.

The transition group worked on a variety of issues including a long-term monitoring and research program to ensure Glen Canyon Dam is operated in a manner consistent with protecting the downstream environment as well as implementation and management of operations and monitoring in consultation with broad-based interests.

The Record of Decision was signed by the Secretary of Interior in October 1996, and in January 1997, Interior Secretary Babbitt signed a Notice of Establishment of the Glen Canyon Adaptive Management Work Group, a federal advisory committee. The charter of this group was signed on January 15, 1997.

All of the elements are now in place for an effective, credible adaptive management effort. The Adaptive Management Work Group is the key; the Technical Work Group providing detailed guidance on issues and objectives; the Science Center to conduct the research and monitoring needed to evaluate operations; and the independent review panel, the outside review necessary to provide the credible science.

The AMWG continues public involvement in the decision-making process and incorporates those stakeholders with interest in the operation of Glen Canyon Dam and downstream resources. By blending the best science and management practices, the AMWG makes recommendations to the Secretary on how to protect the resources and meet the requirement of the law.

The Adaptive Management Program is administered through a senior Department of the Interior official — designee — and facilitated through the AMWG, which is organized as a federal advisory committee and chaired by the designee.

The AMWG held their first meeting on September 10-11, 1997, and officially formed the Glen Canyon Technical Work Group as a subgroup to work on tasks charged to them by the AMWG.

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Colorado River
Colorado River

Contact us

Bureau of Reclamation
William (Bill) Stewart
125 South State Street, Room 8100
Salt Lake City, Utah 84138-1147

Grand Canyon Monitoring & Research Center
Serena Mankiller
2255 North Gemini Drive
Flagstaff, Arizona 86001
Fax: 928-556-7092

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Last Updated: 7/8/24