PAGE, Ariz. – Recreational users of the Colorado River below Glen Canyon Dam are being warned to use caution as a high-flow experiment will send water flooding downstream through Glen Canyon National Recreation Area and Grand Canyon National Park the second week in November.
Up to 36,000 cubic-feet-per-second will be released beginning Nov. 7 causing high water in the river. Water releases will continue for four days.
Caution is urged for the entire week of Nov. 7 as the high water moves downstream.
Flow level information will be posted at multiple locations in both Glen Canyon National Recreation Area and Grand Canyon National Park, officials said in a statement.
It will take several hours following the water releases for high-flow waters to reach and then recede at downstream locations in the canyons.
The high-flow experimental releases of water from the dam are designed to mimic the natural seasonal flooding of the Colorado River through the Glen and Grand canyons that occurred before the construction of Glen Canyon Dam. This will be the fourth such release.
Releases are timed to occur following sediment deposits to the Colorado River from downstream tributaries so that sand stored in the river channel can be picked up by the high-volume water releases and be redeposited downstream as sandbars and beaches.
This year, according to the news release, a significant amount of sediment has been deposited since July as the result of heavy rain and monsoonal activity.
Sand features and associated backwater habitats can 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 news release states.
High-flow releases are expected to benefit recreational users as well by creating more camping beaches.
“There were extensive beaches and sandbars in the canyon prior to the building of the dam,” Rob Billerbeck, Colorado River coordinator for the National Park Service said in an earlier interview.
The natural timing of high-flow events is in the spring, Billerbeck said. However, studies have shown that with the dam in place, fall releases are more effective.
A public comment period for a Glen Canyon Dam long-term experimental and management plan draft ended in May 2016; the final environmental impact statement for the plan was released in early October.
The decision to conduct the experiment was made following substantial consultation with Colorado River Basin states, American Indian tribes and involved federal and state agencies, officials said.
The high-flow experiment will not change the total annual amount of water released from Lake Powell to Lake Mead. Water releases later in the water year will be adjusted to compensate for the high-volume released during the experimental release.
More information about the high-flow experiment will be posted and updated online.
It is suggested that all river and backcountry users check the U.S. Geological Survey Grand Canyon Monitoring and Research Center’s website or call the Grand Canyon National Park River Permits Office, telephone 800-959-9164, before starting a river or backcountry trip to be prepared for variable conditions including higher river flows.
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