GLENWOOD SPRINGS – Two Western Slope water conservation districts are moving forward with the third phase of a “risk study” exploring how much water might be available to bolster water levels in Lake Powell, and they are doing so without state funding to avoid Front Range opposition to the study.

Lake Powell today is half-full and dropping and water managers say several more years like 2018 could drain the reservoir, which today contains 12.3 million acre-feet of water. And the looming water shortage is revealing lingering east-west tensions among Colorado’s water interests.

Officials at the Colorado River Water Conservation District and the Southwestern Water Conservation District, whose boundaries include the Yampa, Colorado, Gunnison, and San Juan river basins on the Western Slope, are eager to answer some forward-looking questions, which were discussed at a meeting in April of the four Western Slope basin roundtables which work under the auspices of the Colorado Water Conservation Board.

How much water in a hotter and drier world might still be available from Western Slope rivers to divert and put to beneficial use, for example.

And how much water might be made available from current water users to send downriver from each of the major Western Slope river basins to help fill Lake Powell?

Those are sensitive questions in Colorado, on both sides of the Continental Divide.

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And powerful Front Range water interests think the state should be answering them, not the two Western Slope conservation districts.

A state agency, the Colorado Water Conservation Board, approved a $32,000 grant in March 2015 to help pay for the first phase for the Western Slope’s “risk study.”

Then the CWCB kicked in $40,000 in March 2017 for the second phase of the Western Slope’s risk study, the results of which were presented in March 2018 to the CWCB.

But that second grant-review process brought opposition from the Front Range Water Council, which unsuccessfully sought to block the requested funding from the Western Slope.

“The opposition to Phase II of the risk study was focused on concerns related to the direction and management of the study coming solely from the West Slope without East Slope involvement, and being funded by the state,” said Jim Lochhead, the president of the Front Range Water Council and the CEO of Denver Water, in a statement released July 20. “Risks on the Colorado River are of statewide concern and any such studies are better conducted by the state, through its Colorado Water Conservation Board.”

On Nov. 9, 2016, Lochhead sent a letter on Front Range Water Council letterhead to the chairs of the South Platte, Metro and Arkansas roundtables urging them to oppose funding for the second phase of the risk study.

“If we are unsuccessful in convincing the state to assert its leadership role in modeling Colorado River Compact administration issues, the FRWC may undertake its own independent modeling effort and ask the three East Slope roundtables to help contribute funding,” the letter said. “However, we would do so reluctantly as modeling by regional interests may only serve to further divide the state.”

The letter also said “We are also concerned that the assumptions used in the Phase I modeling study may be creating biased impressions regarding the amount of the remaining developable water under the compacts.”

The Front Range Water Council is an ad-hoc group that includes Denver Water, Northern Water, Aurora Water, the Pueblo Board of Water Works, Colorado Springs Utilities, the Southeastern Colorado Water Conservancy District, and the Twin Lakes Reservoir and Canal Company.

The first two phases of the Western Slope’s risk study showed that 1 million to 2 million acre-feet of water from current water users may be needed to bolster levels in Lake Powell, especially if more water is also diverted to the Front Range.

Today, irrigators on the Western Slope use about 1.3 million acre-feet of water a year, while the Front Range uses about 541,000 acre-feet from the Western Slope to meet municipal and agricultural demand.

As such, officials at the Western Slope conservation districts are now asking if, say, 10 percent of that water use was cut back over time, in a voluntary and compensated demand management program, and the saved water was banked somewhere — ideally Lake Powell itself — would that be enough to keep the big reservoir full enough to still produce power at Glen Canyon Dam and deliver enough water downstream to meet the terms of the Colorado River Compact?

And if it was enough, how much should come from each Western Slope basin?

On Monday in Glenwood Springs, Andy Mueller, the general manager of the Colorado River Water Conservation District, acknowledged that the 2017 funding request from the Western Slope “ran into a lot of political opposition from the Front Range, basically saying, ‘You guys are asking questions that may harm our state.’ And the questions that were posed in Phase II were essentially dumbed down in order to comply with that request so that we could get the [state funding]. So our board and the Southwestern board voted unanimously to proceed to fund [Phase III of the study] on their own.”

Mueller was addressing the members of the Colorado Basin Roundtable when he described the 2017 process. The roundtable, which reviews grants for the CWCB, had twice voted to fund the risk study, along with three other Western Slope roundtables.

And even without state funding, it’s still important to the two Western Slope conservation districts that the four Western Slope basin roundtables now conceptually support the third phase of the risk study.

On Monday, the members of the Colorado roundtable unanimously passed a resolution to that effect.

Mueller assured the roundtable members that the two districts will work to make the mechanics, and the results, of the evolving water-modeling tool available.

“We really want to make sure that what we’re doing is an open and transparent modeling process,” Mueller said. “Because we think that data that everybody can agree on is data that can then elevate the conversation with respect to the risk in the Colorado River.”

Mueller also told the roundtable that interest from the Front Range is welcomed during the third phase of the study, up to a point.

“We have reached out to the Front Range,” he said. “I went over to their joint roundtable in May and explained to them what we were doing and welcomed their participation, input, their views. Didn’t welcome their censorship, but welcomed their thoughts.”

Editor’s note: Heather Sackett of Aspen Journalism contributed to this story. Aspen Journalism is reporting on water and rivers in the Roaring Fork and Colorado river basins in collaboration with The Aspen Times and other news organizations. The Times published a version of this story on Friday, July 27, 2018. The Vail Daily published the story on July 28, 2018.