Wringing what’s left out of the booming South Platte river basin

Development along the I-25 corridor north of Denver is booming, according to water providers in the South Platte basin. A new proposed storage and re-use plan will help meet demands they say.

By Brent Gardner-Smith, Aspen Journalism

KEYSTONE – Representatives of various water providers in the South Platte River basin said Wednesday they intend to develop 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.

By comparison, Ruedi Reservoir above Basalt holds about 100,000 acre-feet of water and Dillon Reservoir in Summit County holds about 257,000 acre-feet.

“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 permitting and funding, 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, or 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.”

Darling also said, “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 to the IBCC, the reasons to do the big project because it would “maximize use and effectiveness of available water on South Platte” and “minimize traditional agricultural ‘buy and dry.’”

“There is no choice,” Darling told the IBCC. “We have to work together to do this, and we really don’t have a choice.”

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 re-use 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 re-use the water released earlier from the upstream storage facilities. Each time the water went through the system, up to 40 percent could be re-used, 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 re-use 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.”

The project also builds upon a recently completed study of available storage sites in the lower South Platte basin. That study found there was available water to store, and a “long list of possible storage sites,” as well as a wide range of types of facilities, and costs.

A map shown by representatives of the South Platte Regional Opportunities Working Group to the members of the Interbasin Compact Committee on May 2, 2017, Keystone. The map shows three large water-storage facilities and a re-use pipeline back to the north metro area.

Help ag, 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.”

Yahn also told the IBCC, “Basically, we’re trying to give farmer’s options. But you’ve got to have a place to put the water.”

Sean Cronin, the executive director of the St. Vrain and Left Hand Water Conservancy District in Longmont, also served on the working group, which was formed after the 2015 Colorado Water Plan was completed.

“I want to emphasize how significant this analysis and this effort has been, because it’s really a fundamental shift in how the South Platte was thinking of things at that time,” Cronin told the IBCC members. “It was told ‘you need to get your house in order.’ And this is very much in that vein, of getting the South Platte’s house in order.”

He also said “there is a sense of urgency for this. If you’ve traveled on I-25 between, say, north of Thornton to Ft. Collins, there is an absolute crazy boom going on right now in that corridor.”

A new home, complete with lush lawn, not far from I-25 in Thornton. The northern metro area is booming and water providers are willing to use 'buy-and-dry' as a way to move water from the ag sector to the municipal sector.

Price tag?

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

“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 water from the Colorado-Big Thompson project, which serves the northern Front Range, was now “going for $38,000 an acre-foot, and developers aren’t even batting an eye, because houses are now going for $400,000. So, it is on in the South Platte.”

He said the storage and re-use project might actually take pressure off of water supplies from the Western Slope.

“The urgency for what we’re trying to do I think helps, ultimately, the West Slope because these guys are going to be scrambling for buy-and-dry, and when that’s all done they’re going to be looking elsewhere,” he said.

The Moffat Tunnel and water pipe, at Winter Park, is an example of existing transmountain diversion that brings water to the South Platte River basin. While the South Platte working group's project does include new transmountain water, there are concerns it could lead to more such water being shipped under the Continental Divide.

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 IBCCC 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 has 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.”

Bruce Whitehead, the executive director of the Southwestern Water Conservation District in Durango, commented on the South Platte basin’s apparent stance that the project was happening regardless of what the West Slope thought.

“I’m a little concerned about ‘we’re moving forward, with or without you,’” Whitehead said. “I’m not sure that’s the way we’re going to get cooperation.”

He also suggested the West Slope might embrace the project if it also included “an acknowledgement there won’t be any more development of water from the West Slope.”

That drew a chuckle from some IBCC members, as Front Range water interests have said they do not intend to walk away from the Western Slope as a source of water.

There are two “water development concept workshops” set up for the public to learn more about the South Platte project, one on May 10 at 1:30 p.m. at Denver Water’s headquarters in Denver and one on May 15 at 3 p.m. at Northern Water’s headquarters in Berthoud.

Yahn said the two meeting locations does not mean the project is coming from Denver Water and Northern Water.

“Denver and Aurora were part of it, and Northern, but it wasn’t them,” Yahn said. “It was all of us just thinking outside the box together. And taking off our agency hats.”

Editor’s note: Aspen Journalism is collaborating on the coverage of rivers and waters with The Aspen Times. The Times published a shorter version of this story on Monday, May 7, 2018.

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