Water agencies in Colorado’s Front Range are proposing new water storage and conveyance infrastructure, but the plans don’t include a new transmountain diversion to pipe water from the western side of the Rockies to the eastern side.

KEYSTONE, COLORADO – Representatives of various water providers in Colorado’s South Platte River basin said on May 2 they intend to further refine and pursue funding for a new water-storage project that includes 175,000 acre-feet of storage at three locations on the South Platte River system.

The potential project would store 50,000 acre-feet of water in Henderson, just north of Denver, 100,000 acre-feet in Kersey, downstream of Greeley, and 25,000 acre-feet further downriver on the Morgan County line at the Balzac Gage, east of Snyder.

“We think we have something that could help the Front Range and the South Platte, and the state as a whole,” said Jim Yahn, who represents the South Platte basin on the Colorado Water Conservation Board and is manager of the North Sterling Irrigation District.

The proposal, which does not include a new transmountain diversion, is coming from an informal and collaborative working group that included officials from Denver Water, Aurora Water and Northern Water, along with officials from other water providers and users, such as Yahn.

The group called itself the South Platte Regional Opportunities Working Group, or SPROWG, which rhymes with frog.

Now a new regional water organization is expected to be formed to guide the proposal toward funding and permitting, said Lisa Darling, the executive director of the South Metro Water Supply Authority.

Darling was on the working group and she was presenting the project to the members of the Interbasin Compact Committee (IBCC) in Keystone on May 2.

She said the various water providers in the South Platte realized that “not unifying was not an option” and that the group developed “a series of projects that could be linked together to benefit everybody as a whole.”

And, she told the IBCC members, “We have to be able to maintain control of the supply, and not have it leave the state unnecessarily.”

The South Platte River rises in the mountains west of Denver, runs through the city north to Greeley, and then turns east toward the Nebraska line.

According to slides presented by Darling and Yahn to the IBCC, two reasons to do the big project are because it would “maximize use and effectiveness of available water on South Platte” and “minimize traditional agricultural ‘buy and dry.’”

The project, which would provide 50,000 acre-feet of “firm yield,” is based on capturing water in the river at times when it is physically and legally available, such as in wet years, and then storing it for release as needed in a regional water reuse system.

New facilities would include off-channel reservoirs, reclaimed gravel pits, and underground storage facilities at the three strategic locations along the river to give providers more flexibility. There might also be some storage at Julesburg, near the Nebraska state line.

A key component of the project is a long pipeline and pump system from the lower river back to the metro area north of Denver, in order to reuse the water released earlier from the upstream storage facilities. Each time the water went through the system, up to 40 percent could be reused, Yahn said.

“It’s a big one,” said Yahn of the project. “It doesn’t fulfill all the needs, especially on the other basins, but on the South Platte, it could be a pretty big deal.”

He also said the storage and reuse project would be in addition to all the other planned water projects in the South Platte basin, as listed in the “basin implementation plan” developed by the Metro and South Platte basin roundtables.

“It’s not in place of anything,” Yahn said. “It’s not in place of NISP (Northern Integrated Supply Project). It’s not in place of Gross (Reservoir) enlargement. It’s not in place of any of those other things that all of our entities are trying to do on the South Platte to meet some of our water demand.”

Helping Agriculture and Cities?

Yahn said that storage on the river upstream of irrigators on the lower South Platte would allow farmers to sell their water to cities in a more flexible way. They could, for example, fallow a portion of their fields instead of selling the whole farm.

He also said that would spread the potentially negative economic impact of “buy and dry,” which can change the economies of agricultural communities, across a bigger area in the South Platte basin.

“You’re not hurting, economically, any one area,” Yahn said. “You’re spreading it out and farmers are getting a little bit of extra money for their water, using it a little differently, treating it as a commodity, getting some interest out of it. But really, to do that, you need storage.”

The Price Tag?

The project proponents did not provide a cost estimate during their presentation.

“As for costs, the number is gazillions,” Darling told the IBCC members. “It is a very, very large number.”

But not large enough that the working group thought state funding would be needed.

“That was never really talked about at SPROWG, as to where the funding was coming from, or whether there was going to be state funding,” Cronin said. “In fact, it was sort of a presumption that the individual water providers would find enough value in this on a cost-per-acre-foot that they could collectively get there and pull off a project. But we didn’t get there. There was no cost-benefit analysis.”

He said the storage and reuse project might actually take pressure off water supplies from the Western Slope.

Interbasin View

The Interbasin Compact Committee, or IBCC, operates under the auspices of the Colorado Water Conservation Board and is charged with sorting out potential conflicts between basins, especially those brought up by transmountain diversions under the Continental Divide.

It includes two representatives from each of the state’s nine basin roundtables, six governor’s appointees and two members of the state legislature.

The South Platte project does not include new sources of West Slope water, but concerns were still raised by West Slope interests on the IBCC last week that the South Platte project could eventually draw more water through existing transmountain diversions.

Eric Kuhn, the former general manager of the Colorado River Water Conservation District, who remains a governor’s appointee to the IBCC, suggested that the West Slope might want to see “some protections that these reservoirs don’t end up sitting there empty for a long time and that it doesn’t just drag additional transmountain water over the hill.”

T. Wright Dickinson, a rancher along the Green River, also serves as a governor’s appointee on the IBCC.

“I think the South Platte is clearly demonstrating what many around this table have asked, in the context of fully utilizing your own resources,” Dickinson said. “But I have a concern that the project could in fact pull water through existing projects – more water across the divide.”

A longer version of this story was originally published by Aspen Journalism.