As #LakePowell Recedes, River Runners Race To Document Long-Hidden Rapids — KUNC

Sand and silt are piling up on the Colorado River above Lake Powell, as water levels continue to fall due to persistent drought and encroaching aridification. Water managers from San Diego to Wyoming are working to find ways to keep the river’s reservoirs, and water delivery systems, functioning.

From KUNC (Molly Marcello):

Climate change and overuse are causing one of the Colorado River’s biggest reservoirs, Lake Powell, to drop. While water managers worry about scarcity issues, two Utah river rafters are documenting the changes that come as the massive reservoir hits historic low points.

For the past three years, Moab-based river runners Mike DeHoff and Pete Lefebvre have carefully photographed and mapped Cataract Canyon on their boating trips. For decades, Lake Powell buried the lower portion of the beloved canyon under flatwater. But now that the lake’s water levels are dropping, things are rapidly changing in the canyon…

The pair photograph these returning rapids year to year, illustrating in real time what it looks like as Lake Powell’s water levels drop and shift. Lefebvre says he was inspired by Chasing Ice, a 2012 film that documented shrinking glaciers from a sustained rise in global temperatures…

It wasn’t long before their hunt for new rapids sent them digging into the past. DeHoff has spent hours poring over old river maps, guidebooks, and historic photos in search of clues…

Their first “eureka moment” came when they correctly matched a 1921 photo from a survey of the Colorado River with one of their own. The picture shows a boat running through a dynamic stretch of Lower Cataract, where the reservoir’s mostly flatwater exists today. But Lefebvre says, some character is now coming back to the area.

“It started with just like a little ripple in the water to the surface, and then there was a little burble. And then oh, there was the tip of a rock sticking out,” Lefebvre said. “And then another rock was sticking out, and then eventually you start seeing this thing turn into a riffle.”

They named the area La Rue’s Riffle for E.C. La Rue, the U.S. Geological Survey hydrologist who took that photo nearly a century ago.

Fed up with the slow rate of guidebooks, the pair recently published their own supplemental river map on their website, Returning Rapids of Cataract Canyon. It lays out the freshest, gnarliest rapids of the lower canyon…

Cataract Canyon is becoming a well-known place to study what happens to an ecosystem when a reservoir recedes, and a river has a chance to return to a sense of former wildness.

“We’ve taken some people who are highly trained scientists, and geologists, and whatever out there,” DeHoff said. “And it’s really neat to see their faces where they’re like, ‘I’ve been studying geomorphology for 15 years and here I am out here seeing it right before my eyes, happening faster than I can even believe it’s happening.’”

Whether due to overuse, prolonged drought, or political change, researchers are beginning to contemplate a future for a severely diminished Lake Powell. This October the reservoir dropped to just under 11 million acre-feet of water, or just 45% of its total capacity. With a dry and warm winter on the horizon in 2021, there’s no relief on the horizon.

The Returning Rapids project is showing a silver lining to a reduced reservoir, Lefebvre said. It’s not only about new thrills for rafters – they’re also watching an entire ecosystem shift.

“Instead of this monoculture of weeds and a mud canal…we’re getting all this character back with rapids, beaches, currents, eddies, animal life, and native vegetation,” Lefebvre said. “And so that’s how I see [Cataract Canyon] recovering. It’s a nicer place to be now.”

Lake Powell, created with the 1963 completion of Glen Canyon Dam, is the upper basin’s largest reservoir on the Colorado River. But 2000-2019 has provided the least amount of inflow into the reservoir, making it the lowest 20-year period since the dam was built, as evidenced by the “bathtub ring” and dry land edging the reservoir, which was underwater in the past. As of October 1, 2019, Powell was 55 percent full. Photo credit: Eco Flight via Water Education Colorado

Leave a Reply