High-Flow Experiment Underway at Glen Canyon Dam Simulates Natural Flooding through Grand Canyon

Releases from dam help restore ecological health without affecting water commitments

Last edited 09/29/2021

Date: November 7, 2016
Contacts:  Interior_Press@ios.doi.gov
Marlon Duke (Reclamation), mduke@usbr.gov (385) 228-4845

PAGE, Ariz. – The U.S. Department of the Interior today initiated another high-flow release of water from Glen Canyon Dam in Arizona under an innovative science-based experimental plan. The fourth such release, the goal is to enhance the environment in Grand Canyon National Park and Glen Canyon National Recreation Area while continuing to meet water and power delivery needs and allowing continued scientific experimentation and monitoring on the Colorado River. 

“Healthy watersheds are critical to the economy and environment, and our science-based approach demonstrates that protecting water supplies alongside other resources tied to the river are not only compatible but instrinsically linked,” said Secretary of the Interior Sally Jewell. “This latest release will provide critical fish and wildlife habitat, reduce erosion of archaeological sites and enhance recreational opportunities while meeting our obligations to water users in the region.”

The 96-hour-release will pick up enough sand from tributary channels to fill a building as big as a football field and as tall as the Washington Monument, all the way to the brim. These hundreds of thousands of tons of sediment will be re-deposited along downstream reaches as sandbars and beaches along the Colorado River, mimicking natural river flow.

The high-volume experimental releases are designed to restore sand features and associated backwater habitats to provide key fish and wildlife habitat, potentially reduce erosion of archaeological sites, restore and enhance riparian vegetation, increase beaches and enhance wilderness values along the Colorado River in Glen Canyon National Recreation Area and Grand Canyon National Park. The annual volume of water to be sent toward Lake Mead this year will not change as a result of the experiment – water releases in other months will be adjusted accordingly.

The decision to conduct this experiment followed substantial consultation with Colorado River Basin states, American Indian Tribes and involved federal agencies, including five Interior agencies – Bureau of Reclamation, National Park Service, U.S. Fish and Wildlife Service, U.S. Geological Survey and Bureau of Indian Affairs.  

In planning the release, officials considered the amount of sediment available in the river; the condition of cultural and archaeological resources near the river; biological resources such as endangered species, the Lees Ferry recreational fishery and riparian vegetation; and seasonal demands for water and hydroelectric power deliveries. During and after the release, the USGS Grand Canyon Monitoring and Research Center will gather a variety of scientific data, including how beaches and sandbars change, differences in sediment concentration and composition, and water quality.

Recognizing the importance of annual water deliveries and dependable hydroelectric power generation, the Grand Canyon Protection Act of 1992 (Public Law 102-575) directed the Secretary of the Interior to manage Glen Canyon Dam in such a way as to "protect, mitigate adverse impacts to, and improve the values for which Grand Canyon National Park and Glen Canyon National Recreation Area were established."

Former Secretary of the Interior Ken Salazar triggered the first release under the experimental long-term protocol in November 2012. The protocol calls for conducting more frequent high-flow experimental releases and timing them to occur following sediment inputs to the Colorado River downstream from Glen Canyon Dam.

Department of the Interior officials remind recreational users to use extreme caution during the high flows when on or along the Colorado River through Glen, Marble and Grand Canyons. Flow-level information will be posted at multiple locations in both Glen Canyon National Recreation Area and Grand Canyon National Park. 

Additional information about this high flow experiment—including flow information, campsite maps and shoreline modeling—is available at the following websites:

U.S. Bureau of Reclamation - http://www.usbr.gov/uc/rm/gcdHFE/index.html 
National Park Service - https://www.nps.gov/grca/learn/nature/hfe.htm

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