The U.S. Department of the Interior (Interior) with assistance from the U.S. Department of Energy Argonne National Laboratory Environmental Science Division (EVS) completed the Long-Term Experimental and Management Plan (LTEMP) final environmental impact statement (EIS). The LTEMP final EIS is a comprehensive evaluation of 1,312-MW Glen Canyon hydroelectric facility operations and its effects on the Colorado River through the Grand Canyon.
This is the first such evaluation in more than 20 years, according to EVS, and it examines flow regimes to meet the goals of supplying water for communities, agriculture, and industry and will protect the resources of the Grand Canyon, while providing clean hydropower.
In the next few months, Interior is expected to produce a Record of Decision incorporating data from the study. The decision will identify how the department plans to operate Glen Canyon Dam for the next 20 years.
A significant portion of the LTEMP is planning for experimental manipulation of flow, temperature, and other variables, to evaluate uncertainties and improve understanding of the Colorado River ecosystem’s response to dam operations.
The hydropower facility also provides power for more than five million customers. The dam was built in 1963 for water storage and flood control and is crucial to water distribution to about 40 million people in Arizona, Colorado, Nebraska, Nevada, New Mexico, Utah and Wyoming.
Reclamation initiated the Glen Canyon Dam Adaptive Management Program in 1997 to deal with the effects of dam operations on downstream resources in Glen Canyon National Recreation Area and Grand Canyon National Park. The program has conducted a series of high-flow releases to determine whether there is a sustainable mode of dam operation that will rebuild and maintain downstream sandbar habitats. Glen Canyon Dam operations are constrained by factors including turbine flow capacities, cavitation risk, vortex prevention, sandbar protection, operational/manpower limitations, storm flow management and environmental concerns.