About 15 miles upstream of Grand Canyon National Park sits Glen Canyon Dam, completed in 1963. The dam provides hydroelectric power for 200 wholesale customers in six Western States, and it is an important component of the Nation’s western electrical grid system, but it has also altered the Colorado River’s flow, temperature, and sediment-carrying capacity. Over time the operation of Glen Canyon Dam has contributed to beach erosion, invasion and expansion of nonnative species, and losses of native fish.
Public concern about the effects of Glen Canyon Dam operations on the downstream environment in lower Glen Canyon and Grand Canyon National Park prompted passage of the Grand Canyon Protection Act of 1992  , which directs the Secretary of the Interior to operate the dam "to protect, mitigate adverse impacts to, and improve values for which Grand Canyon National Park and Glen Canyon National Recreation Area were established...". This legislation also required the creation of a long-term monitoring and research program to provide information that could inform management policies and decisions related to dam operations and protection of downstream resources.
The USGS Grand Canyon Monitoring and Research Center (GCMRC) is the science provider to the Glen Canyon Dam Adaptive Management Program (GCDAMP). In this role, the GCMRC provides relevant scientific information about the status and recent trends of important natural, cultural, and recreational resources affected by the current operational regime at Glen Canyon Dam. Since 1996, following a 1996 Record of Decision on an Environmental Impact Study for Operations of Glen Canyon Dam, the dam has been operated with a modified low fluctuating flow (MLLF) regime. The Record of Decision also allowed for experimental high flow releases, and other experimental flow regimes, to improve scientific understanding on how to operate the dam to minimize impacts to the environment and hydropower production while improving resource conditions downstream. GCMRC also develops scientific information on other related factors that affect downstream resources, as well as non-flow measures to mitigate adverse impacts. The GCMRC focuses its efforts on three primary activities: (1) monitoring status and trends in resource condition, (2) focused research on specific topics of concern to GCDAMP stakeholders and (3) experimentation.
The GCMRC works closely and cooperatively with a wide range of Federal, State, and Tribal resource management agencies; academic institutions; and private consultants.
The Secretary of the Interior made a formal decision in 1996 that altered historical flows from the dam. This decision also established the Glen Canyon Dam Adaptive Management Program, which got underway in 1997. Adaptive management, also known as “learning by doing,” is a way to evaluate and revise management actions as new information becomes available. Science—in the context of adaptive management—is the “compass” used to chart such changes is course.
The adaptive management program is facilitated by the 24-member Adaptive Management Work Group, a federal advisory committee that provides recommendations on the operation of Glen Canyon Dam to the Secretary of the Interior. The group includes representatives from Native American Tribes, Federal and State resource agencies, Colorado River Basin States, and nongovernmental groups.