The Glen Canyon Dam Adaptive Management Program: Monitoring Progress

Adaptive ecosystem assessment and management emerged as an important resource management strategy in the early 1990s for major river systems in the United States (U.S.).  In 1997, the Glen Canyon Dam Adaptive Management Program (GCDAMP) was formally established by the Secretary of the Interior Department in response to the Grand Canyon Protection Act of 1992 (GCPA).  The GCPA aimed to improve natural resource conditions in the Colorado River corridor in Glen Canyon National Recreation Area and Grand Canyon National Park, Arizona.  The GCDAMP fulfills this statutory requirement by using science (long-term monitoring, modeling and field experiments in an adaptive framework) and a variety of perspectives from 25 stakeholders to support the decision-making process related to dam operations.  Monitoring data collected by the U.S. Geological Survey’s Grand Canyon Monitoring and Research Center and its various cooperators since 1996, have documented improvements to several key biotic and abiotic resources and progress toward improved understanding of the ecosystem have resulted from the GCDAMP since its inception.  Recent biotic responses include (1) an estimated 50% increase in the adult population of endangered humpback chub (Gila cypha) between 2001 and 2009, following previous declines; (2) increased abundance of rainbow trout in the Lees Ferry tailwater in response to artificial flood experiments; (3) a 90%, albeit temporary, decrease in non-native rainbow trout (Oncorhynchus mykiss) below the Lees Ferry tailwater, known to compete with and prey on native fish, during a multi-year removal experiment in a reach used by humpback chub; and (4) widespread, albeit temporary, rebuilding of eroded sandbars in response to an experimental high-flow release of dam water in March 2008. Although progress has been made, the GCDAMP faces several immediate challenges, including (1) defining specific, measurable objectives and desired future conditions for important natural, cultural, and recreational resources to guide science and management; (2) establishing a long-term experimental and management plan; and (3) ensuring long-term funding for monitoring programs to assess ecological responses to management actions. Addressing these challenges and building on recent progress will require ongoing commitments to long term monitoring of resources below the dam, adaptive strategies that promote learning through ongoing, integrated field experiments, and strong and consistent leadership from the U.S. Department of the Interior officials who guide the GCDAMP.