High-flow dam release to benefit Grand Canyon ecosystem

On Monday, Nov. 11, the Department of Interior initiated a high-flow release from Glen Canyon Dam in Arizona.

PAGE, AZ, Nov. 22, 2013 -- On Monday, Nov. 11, the Department of Interior initiated a high-flow release from Glen Canyon Dam in Arizona -- the second release under an innovative science-based experimental plan approved in May 2012.

The goal of the releases is to help restore the environment in Grand Canyon National Park and Glen Canyon National Recreation Area while continuing to meet water and power needs and allowing continued scientific experimentation and monitoring on the Colorado River.

By sending enough water downstream to fill an Olympic-sized swimming pool every few seconds, the 96-hour-release will pick up enough sand from river channels to fill a building as big as a football field and as tall as the Washington Monument, all the way to the brim. Further, these hundreds of thousands of tons of sediment from river channels will be re-deposited along downstream reaches as sandbars and beaches along the Colorado River.

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 reduced to ensure the annual volume is unchanged.

Due to recent rainstorms, the sediment resources currently available for the experiment have reached historic levels -- approximately three times larger than the sediment volume available a year ago. Scientists estimate the sediment deposited by the Paria River since late July at approximately 1.5 million metric tons.

Once Glen Canyon Dam power plant reached full capacity, each of the four river outlet tubes was opened at successive intervals so that the project will reach the peak release of 34,100 cubic-feet-per-second for a total of 96 hours.

The flexible framework provided by the high-flow release protocol of 2012 is intended to better distribute sediment to conserve downstream environmental resources, while continuing to meet the water storage, delivery and hydropower production needs vital to western communities, agriculture and industry. Refinements to the 2013 experiment were made within that framework including consideration of power marketing conditions for the Western Area Power Administration.

The additional water released during the high-flow experiment is part of the total annual water delivery from Glen Canyon Dam to Lake Mead determined in August of each year based on the projected hydrology and forecasted reservoir elevations identified in the August 24-Month Study. The release does not change the annual amount of water released: high flow experimental release flows are included in the total annual volume and are offset by making slight adjustments to the monthly release volumes during other times of the water year.


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