U.S. Geological Survey Fact Sheet 2009-3033
The protection of resources found in Glen Canyon National Recreation Area and Grand Canyon National Park, Arizona, emerged as a significant public concern in the decades following the completion of Glen Canyon Dam in 1963. The dam, which lies about 15 miles upstream from the park, altered the Colorado River’s flow, temperature, and sediment-carrying capacity, resulting over time in beach erosion, expansion of nonnative species, and losses of native fish. During the 1990s, in response to public concern, Congress and the Department of the Interior embarked on an ongoing effort to reduce and address the effects of dam operations on downstream resources.
In 2005, the U.S. Geological Survey produced a comprehensive report entitled “The State of the Colorado River Ecosystem in Grand Canyon,” which documented the condition and trends of resources downstream of Glen Canyon Dam from 1991 to 2004. This fact sheet updates the 2005 report to extend its findings to include data published through April 2009 for key resources.
First posted April 27, 2009
This report is also available in print from:
USGS Information Services, Box 25286,
This report is presented in Portable Document Format (PDF); at least version 7 of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.
Hamill, John F., 2009, Status and trends of resources below Glen Canyon Dam update--2009: U.S. Geological Survey Fact Sheet 2009-3033, 4 p. [https://pubs.usgs.gov/fs/2009/3033/]
Aquatic Food Web
Update of key downstream natural, cultural, and recreational resources affected by Glen Canyon Dam, summarizing data published through April 2009