How much water reaches the Westwater stretch of the Colorado River, and then Lake Powell, is taking on increasing importance to Colorado water officials. A new study is underway to look at much more water is available to develop on the Western Slope, and it's caught the attention of east slope water officials. Credit: Brent Gardner-Smith/Aspen Journalism

PUEBLO – A big question in Colorado is how much water is left to divert and use from the Colorado River before levels drop too low in Lake Powell to make hydropower and deliver water downstream. The answer to that question is of interest not only to water-planning roundtables on the west slope, but on the east slope as well.

Last week, three east slope roundtables, the South Platte, Metro and Arkansas, chose members to sit on a technical advisory committee that is preparing a study on how much water is left to develop on the Western Slope while still keeping the Glen Canyon Dam functioning as it does today.

The roundtable members from the east slope are all senior officials at major water providers including Denver Water, Aurora Water, Colorado Springs Utilities and Pueblo Board of Water Works.

The level of officials eager to join in on what started as a west slope study of the issue is an indication of how important is the question, and the potential answers.

The west slope water study, known as the “risk study,” was originally conceived in December 2014 at a meeting of the four west slope roundtables, which include the Colorado, Yampa, Gunnison, and Dolores, San Miguel and San Juan (or Southwest) roundtables.

The west slope roundtables, especially the Yampa and the Gunnison, found they were not in agreement about future water development on the Western Slope, but they did agree on the need for more information.

“They needed to have a better understanding of what’s going on, on the river,” said Eric Kuhn, the general manager of the Colorado River District, during a Feb. 23 meeting of the Interbasin Compact Committee in Broomfield.

The IBCC includes representatives from each of the state’s nine basin roundtables and serves as a statewide water policy advisory board.

Upon recently learning of the west slope study, the three east slope roundtables asked to be included, which the west slope then agreed to.

“We always intended that this would be open and transparent, and open to the east slope roundtables,” Kuhn told the IBCC members, explaining that the original plan was to invite the three non-voting out-of-basin members serving on the Colorado and Gunnison roundtables to participate in the study.

But those out-of-basin seats, originally set up in 2005, have fallen out of use on the roundtables, so it was agreed to ask the east slope roundtables to choose their own committee members.

And the South Platte, Metro and Arkansas roundtables each met last week and did just that.

The Colorado River in Cataract Canyon, just above Lake Powell, where water officials are keeping a close eye on water levels.
The Colorado River in Cataract Canyon, just above Lake Powell, where water officials are keeping a close eye on water levels. Credit: Brent Gardner-Smith/Aspen Journalism

Committee members

The South Platte roundtable assigned three people: Kevin Lusk, a senior engineer from Colorado Springs Utilities and the president of the Twin Lakes Reservoir and Canal Co.; Jim Yahn, the manager of the North Sterling Irrigation District and a South Platte representative on the IBCC; and Jerry Gibbens, a project manager and water resource engineer at Northern Water.

The Arkansas roundtable also selected three members: James Broderick, executive director of Southeastern Colorado Water Conservancy District; Brett Gracely, manager of Colorado Springs Utilities; and Terry Book, executive director of Pueblo Board of Water Works.

And the Metro roundtable assigned four members: Mark Waage, manager of water resources planning at Denver Water, who is also an IBBC member; Joe Stribrich, planning director at Aurora Water and an IBCC member; Eric Hecox, executive director of the South Metro Water Supply Authority and Kerry Sundeen, a principal engineer and consultant at Wilson Water.

At the IBCC meeting on Feb. 23, Waage thanked the west slope roundtables for allowing east slope participation in the study.

“I think there just was a period of ‘what are they doing, what’s going on,” Waage said. “And the fact that you guys are open to including us is really helpful.

“We would really like to deal with this issue on a statewide basin if we can and in concert with the four other upper basin states,” Waage added. “The east slope feels pretty strongly that that’s our best position. And we ought to always seek that approach rather than a east versus west kind of thing.”

The Colorado River District is managing the study and is seeking state funding on behalf of the participants to help pay for it.

The four west slope roundtables each have approved $8,000 in state funding from their basin accounts, totaling $32,000.

The River District and the Southwest Water Conservancy District have each agreed to put in $10,000, for a total study cost of $52,000.

The Colorado Water Conservation Board is expected to approve the $32,000 in state funding at its next regular meeting on March 16 in La Junta.

A flow map of Colorado's river helps illustrate why so much attention is paid to the Colorado River.
A flow map of Colorado

Tied to framework

The main question the study will seek to answer is, “What is the likelihood of the elevation of Lake Powell going below 3,525 feet under selected water supply and water demand scenarios?”

The cited level of 3,525 feet in elevation is just above the “minimum power pool” level in Lake Powell of 3,490 feet.

If water levels fall below that, then the upper basin states will have trouble delivering enough water to lower basin states to meet their collective obligation under the Colorado River compact.

And a “curtailment” call could then come up the river and some of the biggest water providers on the east slope could be forced to stop diverting west slope water.

“We need to keep in mind that 20 to 25 percent of our consumptive use of Colorado River water is on the east slope,” Waage said. “The majority of those post-compact rights that would be curtailed are on the east slope.”

And that’s why the study is called the “risk study,” as in what’s the risk of triggering a compact call by taking more water out of the Colorado River?

Kuhn said the study is tied to point number four in the conceptual framework, which was developed last year by the IBCC to guide negotiations over a potential new transmountain diversion project.

Point four, as cited in the Colorado Water Plan, says that “a collaborative program that protects against involuntary curtailment is needed for existing uses and some reasonable increment of future development in the Colorado River System, but it will not cover a new TMD.”

In other words, before the state’s water sector builds a new transmountain diversion, it should figure out how it’s going to keep enough water in Lake Powell.

“Those are lots of variables here, so this isn’t a simple effort,” Kuhn told the IBCC about the risk study. “There’s hydrology, demand levels, what’s happening in other states. So you’ve got four or five different variables and there are lots of permutations of different outcomes.”

Kuhn said the study would build on information gathered as part of several other ongoing exploratory efforts.

One effort is a water banking investigation, now 10 years in the making, that is looking at ways ranchers and water providers could use less water in a drought.

An offshoot of that effort is an ongoing two-year “system conservation” pilot program to pay Western Slope ranchers and others to leave water in the upper Colorado River system to flow toward Lake Powell.

Kuhn said the exploratory efforts are important because “at some point in order to maintain reservoir levels in Lake Powell, in order to maintain the system, in order to accomplish framework point number four, which is to avoid a curtailment, we’re going to have to reduce our demands,” Kuhn said.

A third ongoing effort is “contingency planning,” which is studying how to use water released from federal upstream reservoirs, including Flaming Gorge and Blue Mesa, to keep Lake Powell at a certain level.

“What this four-basin roundtable study will do is collect what we’ve done, and educate people on what it is we’re doing, and what the trade-offs are,” Kuhn said.

Jeris Danielson, the manager of the Purgatoire Water Conservancy District and an Arkansas roundtable member, asked Kuhn if the west slope intended to postpone discussion at the IBCC level of a new TMD until the risk study was complete.

Kuhn said the study should be finished by the end of the summer, and that it made sense to develop a common understanding about how the Colorado River works before talking about a new TMD.

“You’ve got to bring the experts, the people who work in this business, up to a common level of understanding before they can have a common platform to help educate everyone else,” he said.

Editor’s note: Aspen journalism and the Aspen Daily News are collaborating on coverage of rivers and water in Colorado. The Daily News published this story on Monday, March 14, 2016.

Brent Gardner-Smith, the founder of Aspen Journalism, and who served as AJ’s executive director until August 2021 and as editor from 2011-2020, is the news director at Aspen Public Radio. He's also been...