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Glen Canyon Dam Long-Term Experimental and Management Plan EIS
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Frequently Asked Questions


Glen Canyon Dam Long-Term Experimental and Management Plan EIS


Why the LTEMP EIS Is Needed

The LTEMP EIS will evaluate dam operations and identify management actions and experimental options that will provide a framework for adaptively managing Glen Canyon Dam over the next 15 to 20 years.

The LTEMP EIS is needed to fully evaluate dam operations and to identify management actions and experimental options that will provide a framework for adaptively managing Glen Canyon Dam over the next 15 to 20 years consistent with the Grand Canyon Protection Act (GCPA) and other provisions of applicable federal law.

There is a need to utilize scientific information developed over the past 15 years to better inform Department of the Interior decisions on dam operations and other management and experimental actions so that the Secretary may continue to meet statutory responsibilities for protecting downstream resources for future generations, conserving species listed under the Endangered Species Act, and protecting American Indian Tribal interests, while meeting water delivery obligations and generating hydroelectric power.

The EIS will evaluate specific alternatives that could be implemented to meet the GCPA's requirements and to minimize—consistent with law—adverse impacts on the downstream natural and cultural resources and visitor use in Glen Canyon National Recreation Area and Grand Canyon National Park, including resources of importance to American Indian Tribes.

Background

Glen Canyon Dam was authorized by the Colorado River Storage Project Act of 1956 and completed by the Bureau of Reclamation (Reclamation) in 1963. Below Glen Canyon Dam, the Colorado River flows for 15 miles through the Glen Canyon National Recreation Area, which is managed by the National Park Service (NPS). Fifteen miles below Glen Canyon Dam, Lees Ferry, Arizona, marks the beginning of Marble Canyon and the northern boundary of Grand Canyon National Park.

The major function of Glen Canyon Dam is water storage and flood control. The dam is specifically managed to regulate releases of water from the Upper Colorado River Basin to the Lower Colorado River Basin to satisfy provisions of the 1922 Colorado River Compact and subsequent water delivery commitments, and thereby allow states within the Upper Basin to deplete water from the watershed upstream of Glen Canyon Dam and utilize their apportionments of Colorado River water. Another function of Glen Canyon Dam is to generate hydroelectric power.

Grand Canyon Protection Act of 1992

The Grand Canyon Protection Act of 1992 (Pub. L.102–575) (GCPA) addresses potential impacts of dam operations on downstream resources in Glen Canyon National Recreation Area and Grand Canyon National Park. The GCPA required the Secretary of the Interior to complete an EIS evaluating alternative operating criteria that would determine how Glen Canyon Dam would be operated "to protect, mitigate adverse impacts to, and improve the values for which Grand Canyon National Park and Glen Canyon National Recreation Area were established."

The final EIS was completed in March 1995. The Preferred Alternative (Modified Low Fluctuating Flow Alternative) was selected as the best means to operate Glen Canyon Dam in a record of decision (ROD) issued on October 9, 1996. In 1997, the Secretary adopted operating criteria for Glen Canyon Dam (62 FR 9447) as required by Section 1804(c) of the GCPA.

Additionally, the GCPA required the Secretary to undertake research and monitoring to determine if revised dam operations were achieving the resource protection objectives of the final EIS and ROD. These provisions of the GCPA were incorporated into the 1996 ROD and led to the establishment of the Glen Canyon Dam Adaptive Management Program (GCDAMP), administered by Reclamation, and of the Grand Canyon Monitoring and Research Center within the U.S. Geological Survey (USGS). The LTEMP will be coordinated with the existing Glen Canyon Dam Adaptive Management Program.

Glen Canyon Dam Adaptive Management Work Group (AMWG)

The GCDAMP includes a federal advisory committee known as the Glen Canyon Dam Adaptive Management Work Group (AMWG), a technical work group, a scientific monitoring and research center administered by the USGS, and independent scientific review panels. The AMWG makes recommendations to the Secretary concerning Glen Canyon Dam operations and other management actions to protect resources downstream of Glen Canyon Dam consistent with the GCPA and other applicable provisions of federal law.

The decision by the Secretary to develop the Glen Canyon Dam Long-Term Experimental and Management Plan EIS is a component of its efforts to continue to comply with the ongoing requirements and obligations established by the GCPA and recommendations of the AMWG. Reclamation and NPS will co-lead this effort because Reclamation has primary responsibility for operation of Glen Canyon Dam and NPS has primary responsibility for Grand Canyon National Park and Glen Canyon National Recreation Area.