Outlook grim for Colorado River Basin reservoirs

Good snowpack not enough

BY SHANNON MULLANE THE COLORADO SUN

e healthy snowpack whitening Colorado’s mountain peaks has given water o cials some breathing room to manage the Colorado River Basin’s ongoing drought. e challenge will be not to squander it.

As winter storms wind down, water managers and policymakers are mulling over decisions about how to release and retain water in shrunken reservoirs across the basin, which supports 40 million people across the West. is year, many Colorado reservoirs will have the chance to re ll, but the situation is still grim for the two largest reservoirs in the system, Lake Mead and Lake Powell.

“While having a decent year of snowpack doesn’t solve all of our problems, it does give us a little bit of breathing room to focus on longerterm issues,” said Amy Ostdiek, chief of the interstate, federal and water information section at the Colorado Water Conservation Board, the state’s leading water agency.

Western Slope basins that feed the Colorado River have seen above-average snowpack this year, and some areas of the Colorado River Basin have reported record levels of snow, according to Natural Resources Conservation Service data.

“ e challenge that the basin states face is, what will people do in response to this gift, this tremendous success?” said Chuck Cullom, executive director of the Upper Colorado River Commission, an interstate water administration agency. “Are we going to squander it? Or are we going to store it and rebuild resiliency in this potentially once-in-a-decade, potentially once-in-a-century, type of runo ?” e system helps water managers control when and how water moves through the diversions, ditches, streams and rivers in the basin, and acts as a savings bank for dry years. Together, Lake Powell on the Arizona-Utah border and Lake Mead on the Nevada-Arizona border hold about 83% of the total storage capacity for the basin. e issue is that the Colorado River Basin is in a 23-year megadrought and those reservoirs are running short on water savings. If Lake Powell and Lake Mead fall too low, they cannot produce hydroelectric power — or release water to downstream users at all.

Reservoirs that capture Colorado River Basin water can hold, in total, about 60 million acre-feet of water.

As of early April, the basin’s entire reservoir storage system held about 19 million acre-feet, or about 32% of its capacity, according to the Bureau of Reclamation. An acre-foot is enough water to supply two to three U.S. households for a year.

“It would take something like six years in a row like this year to re ll these reservoirs, and no one thinks that’s very likely,” said Brad Udall, senior water and climate scientist at the Colorado State University Colorado Water Center. “I don’t think we’re ever going to see these reservoirs ll fully again, based on what we’ve seen in the last 23 years and based on what climate science tells us we’re in for in the future.”

Lake Mead and Lake Powell have fallen to critical levels in recent years, prompting emergency releases from upstream reservoirs. Last summer, the federal government directed states to develop a plan to cut water use by 2 million to 4 million acre-feet in 2023.

“We’ve had a wet winter; we’re all joyous. is is in no way any kind of a solution,” U.S. Sen. John Hickenlooper said in a recent news brie ng in Grand Junction with Bureau of Reclamation Commissioner Camille

Touton and other o cials. “It gives us a little more time to gure out what the solution will be.” e water elevation at Lake Powell was at 3,522 feet above sea level and about 22% of its full capacity. Below 3,490 feet in elevation, Glen Canyon Dam can’t produce hydroelectric power, and below 3,370 feet, it can’t send water downstream to Lake Mead. e last time Lake Powell hovered around 3,522 feet was in 1967 and 1968 when the reservoir was still lling, according to Bureau of Reclamation historical data. e reports, known as the 24-Month Study, project scenarios of monthly conditions in the Colorado River Basin two years out, including a most probable outcome and best- and worst-case scenarios.

At the end of March, Lake Mead’s water elevation was 1,046 feet, about 183 feet less than its full capacity. Below 895 feet in elevation, water can’t pass through Hoover Dam to downstream users, and below 950 feet, the dam can’t produce hydroelectricity.

Each month, water insiders keep a close eye on projections from the Bureau of Reclamation about how much water will likely enter and leave reservoirs around the basin.

In the most-probable scenario, Lake Powell will likely see about 10 million acre-feet of water ow into the reservoir by the end of September, and the dam will likely release about 7.8 million acre-feet downstream, according to the March report. By the end of the water year in September, the lake is projected to rise by about 35 feet to an elevation of 3,557 feet. at downstream release is on the low end of what’s allowed by management guidelines set in 2007. e reservoir is still on the knife’s edge, Udall said. at’s driven largely by the amount of uses in the Lower Basin as of March 1, Cullom said in early April during a Southwestern Water Conservation District event.

Lake Mead will likely keep dropping, the report showed. Hoover Dam is projected to receive about 7.8 million acre-feet from Glen Canyon Dam and to release about 8.7 million acre-feet of water during the water year. Lake Mead’s elevation will fall by about 12 feet to 1,034 by the end of September.

“People should live within the supply that’s available. In the Lower Basin, that means rebuild your storage by managing your uses downward,” he said. “I believe they will, but we will see.”

In Colorado, this year’s snowpack gives the state’s reservoirs a muchneeded opportunity for recovery, Ostdiek said.

In 2021, Upper Basin states, which include Colorado, New Mexico, Utah and Wyoming, released a total of 161,000 acre-feet from Blue Mesa Reservoir in western Colorado and Flaming Gorge in southern Wyoming to shore up the water supply in Lake Powell. In 2022, Flaming Gorge released over 400,000 acre-feet. Cullom said the debt from those reservoirs will be repaid this year.

“In the Upper Basin, we’re taking this opportunity to repay the loans from Flaming Gorge and Blue Mesa. at’s not squandering this opportunity,” he said. “A failure is when we have in ows of this magnitude and we do not rebuild storage in Lake Powell and Lake Mead. at’s a challenge for Reclamation. It’s, more importantly, a challenge for how the Lower Basin manages its water use.” is story is from e Colorado Sun, a journalist-owned news outlet based in Denver and covering the state. For more, and to support e Colorado Sun, visit coloradosun. com. e Colorado Sun is a partner in the Colorado News Conservancy, owner of Colorado Community Media.

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