Healthy #snowpack provides water for long-delayed Grand Canyon environmental flood —

Glen Canyon High Flow Experiment November 2013 via Jonathan Thompson

Click the link to read the article on the website (Brandon Loomis). Here’s an excerpt:

Grand Canyon advocates are celebrating a decision by federal water managers to unleash a three-day pulse of high water from Glen Canyon Dam to rebuild beaches and improve environmental conditions on the Colorado River. The high-flow experience is scheduled to start Monday. Environmentalists, river runners and others had sought such a flood release, outlined under the dam’s adaptive management program, for years. Healthy monsoon rains had pushed tons of sand into the river, but had also gouged the beaches and sandbars that create natural backwaters and campsites for river trips. Opening the dam’s floodgates before the fresh sediment gradually washed downstream could push the sand up to form new beaches. Their efforts previously ran into the reality of declining water behind the dam in Lake Powell, where the U.S. Bureau of Reclamation was trying to hold back enough water to keep generating hydropower. In response under the Grand Canyon Protection Act of 1992, the agency can release floodwaters when the Paria River dumps sufficient sand below the dam, but had not done so since 2018. This winter, the Rocky Mountains piled up more snow than at any time since 2011, with enough water content to raise the reservoir by dozens of feet.

Before and after photos of results of the high flow experiment in 2008 via USGS

Reclamation’s Upper Colorado Region confirmed the plan on Tuesday. On Friday, the agency sent interested parties a memo explaining its decision to go ahead with a 72-hour release of extra water beginning Monday. Dam operators will open bypass tubes to roughly quadruple the river’s flow to 39,500 cubic feet per second.

The government has conducted several such high-flow experiments in the past, but this will be the first to occur in spring, the natural time for flooding before Glen Canyon Dam’s completion in 1963.

“A springtime (flood) is an opportunity to see all the natural processes that are kicked in by a high flow and see how they respond,” said Kelly Burke, who directs Wild Arizona’s Grand Canyon Wildlands Council.

Leave a Reply