U.S. Bureau of Reclamation officials have issued a draft environmental assessment that proposes a decade-long series of experimental high-flow releases of the Colorado River from Glen Canyon Dam and through Grand Canyon National Park.
The draft comes more than a year since Interior Secretary Ken Salazar called for more high-flow releases and nearly three years since the last one was allowed by BuRec, which at times has been seen at odds with the National Park Service over these orchestrated flows.
While the Park Service desires the high flow "washes" that scour the river corridor through the Grand Canyon, BuRec, which manages the Glen Canyon Dam in large part for its hydropower generation, at times has been seen as opposing a regular series of releases that might mimic natural surges of the Colorado River that occurred before the dam went into service in 1963.
The draft EA examining a long-term protocol for the releases, one that would run from 2011 through 2020, came out last Thursday. (While the release states that public comment will be taken for 30 days, it also says "written comments may be provided to Reclamation through February 14, 2011," or five days shy of 30.)
What BuRec officials want to learn through the high-flow "experiments" is "whether and how sand conservation can be improved in the Colorado River corridor downstream of the dam."
The protocol will provide an adaptive management framework to learn how to better conserve the limited sand supply to the Colorado River below the dam, while ensuring that no significant impacts occur to other downstream resources affected by the high releases.
During a high flow experiment, the high volume of water released from the dam suspends sand stored in the river channel deposited by tributaries. A portion of that sand is re-deposited in the downstream river reaches as sandbars and beaches while another portion is transported downstream by river flows. These sand bars and beaches, and the associated near-shore habitats, are important components of the Colorado River ecosystem in addition to providing camping opportunities for river runners and hikers along the Colorado River within Grand Canyon National Park.
Among questions to be answered through these flows is whether they could help replenish sand bars and beaches throughout the canyon; benefit native fishes such as the humpback chub while making conditions worse for non-native fishes; what impacts they might have on recreation in the canyon, and; how would vegetation respond?
The current draft EA calls for releases of up to 45,000 cubic feet per second.
"The timing of high-flow releases would be March-April and October-November, and the magnitude may range from 31,500 cfs to 45,000 cfs, and the duration may range from one hour to 96 hours," the draft says.
At times the Park Service and BuRec have encountered friction over this issue. Indeed, the last time a high-flow release was scheduled, in March 2008, BuRec officials didn't bother to send their draft EA on that release to Grand Canyon officials until the day before comments were due.
You can view a copy of the EA at this site. A printed copy of the report is available at the Bureau of Reclamation Upper Colorado Regional Office, 125 South State Street, Room 7218, Salt Lake City, Utah 84138.
Written comments may be provided to BuRec through February 14, 2011 to the address above or via [email protected] . For more information, or to request a printed or CD-ROM copy of the EA, please contact Dennis Kubly at (801) 524-3715.