Rafters and kayakers on the Grand Canyon in late April better hope they tied their boats up well at camp as federal operators of the Glen Canyon Dam upstream opened the dam’s jets on Monday, April 24, to begin a 39,500-cfs surge release to restore habitat,, sending what they described as “a pulse” of water whooshing through the canyon.
The release is the first one regulators have made in five years to try to revitalize canyon ecosystems the way nature once did. U.S. Bureau of Reclamation officials said the surge will be in effect until Thursday at midnight , ensuring a 72-hour flow at 39,500 cfs, requiring 270,000 acre-feet of water. The water in the “High Flow Experiment” normally would have flowed gradually over the month of April out of Lake Powell. (Since 2018, dam operators haven’t released simulated flood surges due to long-term drought and low reservoir levels.)
For paddlers on the Grand during this time, it means some big, big water (keep it straight and punch it).
“A lucky-few river runners will get on the three-day 39,500-cfs habitat flow,” says Tom Martin of Arizona’s River Runners for Wilderness. “Some folks will do a layover and watch the “high water” roll on by to avoid it. I encourage all river folks willing to get out there and ride it.”
Martin adds that it’s a bit of a return to river running of yesteryear. “Don’t forget the old-timers running the river before the construction of the Upper Basin Storage Act dams thought that 40,000 to 50,000 cfs was the ideal flow to boat Grand Canyon,” he says. “Pre-Glen Canyon Dam, the lowest late spring-early summer snowmelt peaks were around 40,000 cfs. Think about that—those were the lowest peaks. At flows of 10,000 cfs, the old-timers wouldn’t even show up at Lee’s Ferry. As to the longterm sediment on beaches in Grand Canyon, these habitat flows are slowing the sediment loss which is good. A better option awaits: the removal of Glen Canyon Dam and a return to real seasonal habitat flows.”
The sediment issue, say officials, is the main purpose of the release. “The goal of the High Flow Experiment (HFE) is to move sand stored in the river channel and redeposit it to rebuild eroded sandbars and beaches downstream of the Paria River in Grand Canyon National Park,” reads a report on the NPS website.
The U.S. Department of Agriculture’s latest snow survey data show snowpack in the upper Colorado River Basin at 129% of the 30-year average. Federal hydrologists estimate 14.7 million acre-feet of water will flow from Colorado, Wyoming and Utah into Lake Powell this summer.
Read more (and watch video of 2018 release) here: