Is Utah already overusing its share of water from the Colorado River?

A new report says climate change has reduced flows by nearly 20% since 2000, leaving less water for Upper Colorado River Basin.

(Francisco Kjolseth | The Salt Lake Tribune) Seth Arens, a research scientist for Western Water Assessment, tracks changes in vegetation and eco systems occurring in areas where Lake Powell once was as he documents specific locations year after year including a spot near Water Hole Canyon.

Western states in the upper half of the Colorado River Basin have claimed for years that they’re entitled to far more of the water than they’ve historically pulled from inside the river’s banks. Utah in particular has said it should be getting up to 300,000 more acre-feet than the 1.1 million it uses a year, a claim that has been cited to support various water diversion proposals, such as the Lake Powell pipeline now under review.

Such claims may have been true decades ago, but under pressure from climate change the river’s flows have declined to the point that Utah, New Mexico and Colorado are now using about 500,000 acre-feet more than their annual share, according to a study released Monday by Utah Rivers Council and several other environmental groups.

The new 85-page report, titled “A Future on Borrowed Time,” highlights what its authors say are uncomfortable truths for water managers who seem to operate in denial of the West’s thinning snowpacks and shrinking reservoirs. And the deficit may only get worse should flows continue dwindling in the face of warming temperatures and reduced precipitation in the West

“The water crisis in the Colorado River Basin gets more dire everyday,” said Jen Pelz, Wild Rivers Program Director for WildEarth Guardians, said in a call with reporters Monday. “This report makes plain that additional dams and diversions from the Colorado River are not only irresponsible, but put the entire basin and the communities that benefit from its water at risk of economic, environmental and cultural collapse. We need real and immediate commitments, especially from the Upper Basin states, to live within the river’s means.”

The Utah Department of Natural Resources was not able to make an official available Monday to provide a rebuttal. The release of the report was timed to coincide with Tuesday’s start of the Colorado River Water Users Association’s meeting in Las Vegas.

Some 40 million people in the fast-growing American Southwest rely on the Colorado for at least some of their water. Under a century-old agreement between seven Western U.S states in the Colorado Basin, the Upper Basin is to release an average 7.5 million acre feet of the river’s flow into the Lower Basin, plus Mexico’s share. The four upper states divide what is left, and for Utah that share is 23%.

Utah water officials have long pegged the volume of that share at 1.3 million acre-feet per year, at least 200,000 more than the state draws out. This year, the state established the Colorado River Authority of Utah with the specific aim of ensuring Utah gets what official’s say in Utah’s full share of the river.

But the figure the state cites assumes the Upper Basin should receive 5.7 million acre feet, as was the norm before longterm “megadrought” set in at the end of the 1990s.

During the first 20 years of the 21st century, flows are on average 19% less than what they were over the proceeding century, according to Zach Frankel, executive director of the Utah Rivers Council and a key author on the report along with policy analyst Nick Halberg

“There is a 500,000-acre-foot deficit of water use in the four Upper Colorado River Basin states, specifically Colorado, Utah and New Mexico are overusing their rights to water,” Frankel said in Monday’s call with reporters. “The Colorado River has shrunken flows, and as that’s happened, the reservoirs of the Colorado have shrunk alongside it.”

According to the the report, the 240,000-square-mile Colorado Basin’s sprawling system of reservoirs stores four years worth of the river’s flows. Today those reservoirs are about half full and shrinking, while the two largest — Lake Powell and Lake Mead — are about a third full. Both face the prospect of shrinking to the point of hitting “dead pool,” the point at which they no longer function as reservoirs. Long before wilting to dead pool, the dams at the two once-massive lakes would stop generating electrical power that many utilities rely on to serve customers.

“Refilling these reservoirs in one annual spring snowmelt would require a spectacular runoff event, one larger than any that have been observed in the past 115 years,” the report states. “Yet water leaders in the Upper Colorado River Basin are staking their future—at billions of dollars to the taxpayer – on a series of new water diversion projects.”

Proposed diversions, such as Utah’s Lake Powell pipeline, could wind up taking water from existing users if flows keep declining, the report alleges.

“The Upper Division States are well aware of their rights and obligations under the Law of the River,” the Upper Colorado River Commission said in a statement. “There are challenges across the Colorado River Basin and we are committed, as we have been for years, to advancing sustainable solutions.”

During the 20th century, an average of 15.2 million acre-feet a year passed Lee’s Ferry, a major gauge just below Glen Canyon Dam. Since 2000, that annual average has plunged to 12.4 million acre-feet. That means the Upper Basin’s pie today is nearly 39% smaller than pre-2000 times, 4.1 million vs. 6.9 million, according to the report.

With this math, Utah’s share would be a little less than 950,000 acre-feet, down nearly 200,000 acre-feet than the state now draws. Colorado’s annual share would be 2.1 million, Wyoming’s 600,000 and New Mexico’s 500,000.

“The big question is, are we at the end of the water decline?” Frankel said. “Are we done experiencing reductions of Colorado river flows in this century?”

Probably not, given forecasts that climate change will likely worsen, resulting in even skimpier snowpacks to feed the 1,450-mile river and tributaries. So the report analyzes additional scenarios where flows decline another 30% and another 40%. Under the 40% scenario, the Upper Basin’s deficit would expand to 3.8 million acre-feet.

“Colorado [state] is already in a 400,000-acre-foot deficit,” Pelz told reporters. “If you’re using common sense, Colorado should be reducing its diversions, not increasing them. This is climate denial at its finest. Any additional diversion from the Colorado River at this point will fundamentally harm not only the overall health of the people and the cultures and ecosystems, but all of the current water users.”

And not just current users are at risk, but also many of the 30 American Indian tribes that have a claim to the river and have yet to develop their share, according to the report.

“We all have to stand up and say, damn the status quo, it’s time to get serious,” said John Weisheit, conservation director of Moab-based Living Rivers. “So obviously no more new dams and diversions, and no more business as usual. It’s as simple as that.”