Glen Canyon Dam operational flows to be modified March 15-26

Media Contact: Linda Friar, 786-385-0067,
Lee Traynham, 801-524-3752,

For Release: March 08, 2021

Grand Canyon by USGS and Freshwater Illustrated
Grand Canyon by USGS and Freshwater Illustrated
PAGE, Arizona — The Department of the Interior will implement a spring disturbance flow at Glen Canyon Dam March 15 to 26, 2021. The operation will coincide with required maintenance on the concrete apron downstream of the dam and powerplant. The spring disturbance flow will not affect the monthly or annual release volumes from Lake Powell.

Lake Powell releases through Glen Canyon Dam will be reduced to 4,000 cubic feet per second beginning March 15. Flows will begin a gradual increase on March 20, will peak at 20,150 cfs on March 22 and will remain steady at that level until March 25. Typical flows in March range from a daily low of 8,000 cfs to daily highs around 15,000 cfs. Standard operations will resume on the morning of March 26. The disturbance flows are designed to simulate a spring-timed runoff event. As the changing flows disturb river bottom habitats, ecosystem responses may include elevated algae and insect production resulting in increased aquatic insect prey for endangered humpback chub, non-native rainbow trout, and other wildlife. The flows also may affect the non-native brown trout in Glen Canyon by reducing survival of emerging young, which may help protect native fish in the river. Scientists will study the effects of the modified flows in Glen, Marble, and Grand canyons and the resulting data may be used to make future recommendations on how to better support the Colorado River ecosystem.

“Scientific studies like these are an important part of our obligation to effectively balance the need for water and power resources with responsible stewardship of the Colorado River ecosystem,” said Reclamation’s Upper Colorado Basin Regional Director Wayne Pullan. “This spring disturbance flow was developed and proposed by agency experts from the Bureau of Reclamation, U.S. Geological Survey, and Western Area Power Administration in close collaboration with Colorado River stakeholders, with strong support from environmental and recreational interests. I applaud the partnership and collaboration of the Glen Canyon Dam Adaptive Management Work Group, including all seven basin states and five Native American tribes, to continue our successful adaptive approach to managing Glen Canyon Dam.”

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Relevant Link:

Glen Canyon Dam Spring Disturbance Flow