Lake Powell: Water from upstream reservoirs cannot sustain the reservoir forever, officials say




CNN

Reservoirs in the Colorado River basin may not hold enough water to keep Lake Powell above a critical threshold indefinitely, federal officials have warned in recent weeks as the West’s ongoing megadrought drains water.

The Green River’s Flaming Gorge Reservoir, which is releasing large amounts of water this year downstream to help Lake Powell, may have enough water left for two more similar emergency releases, U.S. Bureau of Reclamation officials told CNN, though they haven’t yet. to fully model the situation.

Federal officials took emergency action in May to use water from upstream reservoirs to raise the level of Lake Powell and buy nearby communities more time to build the Glen Canyon Dam, whose reservoir will soon be too low.

The dam is a key source of energy for the region, generating power for 5.8 million homes and businesses in seven states, and is at high risk of being taken offline if the lake level drops below 3,490 feet above sea level.

Lake Powell’s water level was about 3,529 feet Thursday, or 24 percent full.

Water managers have worked hard to prevent Powell from falling below its critical threshold. Their first step was to release more water from larger reservoirs in the Colorado River basin, like Flaming Gorge. The second was to hold the water in Lake Powell itself, instead of sending it downstream to Mead, the largest reservoir in the country.

But using Flaming Gorge water to keep Lake Powell afloat was just a “buffer,” according to Jim Prairie, head of the agency’s Upper Colorado Basin research and modeling team, and could not be a long-term solution. Prairie said in August that, based on water levels at the time, Flaming Gorge would only be able to handle two more similar emergency releases.

“What this [process] what it’s doing is protecting us for a year, and we’ll probably be able to do that maybe twice as long, and then there won’t be any more capacity,” Prairie said. “So something else is going to have to fill that 500,000 acre-feet, some other mechanism. one”.

Water is being sent from Flaming Gorge to Lake Powell on a monthly basis to fill a total of 500,000 acre-feet by the end of April 2023, according to the bureau. Because of the release, the level in Flaming Gorge is expected to drop by approximately 9 feet, although it will help increase Lake Powell’s elevation by about 16 feet.

Prairie said the biggest challenge is finding long-term solutions to the basin’s crisis.

“And that is really the challenge that everyone faces [Colorado River] Basin states,” he added. “How can we collaborate and work together to find ways to support these additional needs in these reservoirs?”

Eric Kuhn, retired former manager of the Colorado River Water Conservation District, told CNN that’s not a surprise at all.

“There’s really only one reservoir upstream — Flaming Gorge — that has significant capacity,” Kuhn said. “And they’ve used it two years in a row with about 700,000 acre-feet.”

Notably, Prairie’s forecast for Flaming Gorge does not take into account future weather in the West. For example, a wetter-than-average winter this year, which would replenish all reservoirs in the Colorado River basin, could negate the need for emergency releases.

But Kuhn said that wouldn’t be good news for Lake Powell.

“Filling these empty reservoirs is first, that’s where the water goes first,” Kuhn said. “If you steal from Pete to pay Paul, the next time we have a significant runoff, a lot of water will go into recovery storage in these upstream reservoirs, which will reduce Powell’s inflow, so it reduces Powell’s recovery rate. Above average, a wetter year ».

Justin Mankin, head of the National Oceanic and Atmospheric Administration’s Drought Group, previously told CNN that managing water in the Colorado River Basin through all its reservoirs is “like the central bank of an economy, pulling money out of local banks.” capable of sustaining the economy.”

“Lake Powell is the central bank of the Colorado River basin,” Mankin said. “Maybe this is doable for a short time, but like a household, the longer the debt, the more difficult it is. And really the same thing happens with these reservoirs.’

Flaming Gorge Dam in the Colorado River Basin.

Without the emergency measures it has enacted this year, including the Flaming Gorge layoffs, the Glen Canyon Dam estimated there was a 25 percent chance by January.

“They all rely on the collective storage of the watershed,” Jack Schmidt, director of the Colorado River Studies Center at Utah State University, told CNN. “The main problem is total system-wide storage.”

Throughout the year, water discharges from the Flaming Gorge and Blue Mesa reservoirs will continue until October; meanwhile, Navajo Lakes on the border of Colorado and New Mexico will increase in November and December. As a result of these emergency releases, each reservoir will see a major drawdown: four feet in Flaming Gorge; eight feet on Blue Mesa; and two feet in Navajo Lake.

Schmidt said it’s important to remember that all reservoirs are connected. The total capacity of all federal reservoirs in the Colorado River basin is about 58 million acre-feet, of which 50 million are in Lake Powell and Lake Mead combined.

“If you add all the water in all the reservoirs, the system is now at 34% of capacity,” Schmidt said.

Decisions made in Lake Powell will always affect its neighbor across the river, Lake Mead. Due to the low level of Lake Mead, in August the federal government announced further water cuts for the Southwest, which will begin in January 2023.

The Colorado River Basin provides water and electricity to more than 40 million people in seven Western states and Mexico, including homes, farms, ranches and Native communities.

CORRECTION: An earlier version of this story had a caption that listed the incorrect location of the Flaming Gorge Dam. It is on the Green River.