Facing an abysmal snowpack and spring runoff, the state’s largest Front Range water provider has enacted an agreement that lets it take more water from the Western Slope for a limited time.
On March 18, Denver Water put the Shoshone call reduction agreement into effect with water rights owner Xcel Energy, which allows Denver Water to divert more water from the headwaters of the Colorado River in an attempt to alleviate shortages. The agreement reduces the call at the Shoshone hydroelectric plant in Glenwood Canyon by half, from 1,408 cfs to 704 cfs.
The call reduction can only be implemented when two drought conditions are met: an April to July streamflow forecast for the Colorado River measured at the Kremmling stream gauge must be at 85% or less than average and the forecasted storage for the 10 largest Denver Water reservoirs for July 1 must be at or below 80% full.
The March water supply outlook from the National Resources Conservation Service for the Colorado headwaters from Kremmling to Glenwood Springs was 56% of normal. Experts expect conditions to have worsened when the April forecast comes out next week.
This winter is shaping up to be one of the worst on record and since water supplies depend on snowmelt, municipal water providers have been quick to implement cutbacks this spring. Last week, Denver Water declared a Stage 1 Drought and will impose two-day-a-week outdoor watering restrictions this summer.
“In the wake of the worst snowpack conditions in some 50 years of records at Denver Water, we began exercising the Shoshone Relaxation Agreement with Xcel Energy starting March 18,” Denver Water’s Media Relations Coordinator Todd Hartman said in an email. “We have taken this step only one other time under the 2007 agreement with Xcel (2013) and we don’t do so lightly.”
According to the agreement, Denver Water will be able to divert additional water until May 20.
The water provider, which serves about 1.5 million people on the Front Range, gets roughly 50% of its supply from the Colorado River basin and brings it across the Continental Divide through a highly engineered system of tunnels and reservoirs that facilitate the so-called transmountain diversions.
The Shoshone water rights, which date to 1902, are some of the largest and most powerful on the mainstem of the Colorado River in the state. They can command the river’s flows all the way to its headwaters, ensuring water keeps flowing downstream on the Western Slope.
When the plant’s turbines are spinning, it can “call” for its full water right, effectively forcing upstream water users with junior rights – like Denver Water – to cut back. And because the water is returned to the river after it runs through the plant’s turbines, Shoshone benefits downstream cities, irrigators, recreators and the environment on the Western Slope.
Reducing the call means that water can be used elsewhere by other entities.
Western Slope benefit
The call relaxation doesn’t just benefit the Front Range. As part of the agreement, Denver Water will make available to entities on the Western Slope 10% of the water it is able to divert as a result of the call reduction. The water provider will cooperate with the Glenwood Springs-based Colorado River Water Conservation District to determine who gets the water.
River District Director of Technical Advocacy Brendon Langenhuizen said there’s not an official process for deciding how that water will be used, but the district will be reaching out to stakeholders for input.
“We don’t know the yields yet, we don’t know where it will go,” Langenhuizen said. “I think we’re going to see how this year shapes up and how much water we are actually talking about.”
The agreement also allows Denver Water to store additional water in Dillion, Williams Fork and Wolford reservoirs now and release it later in the year to help boost late summer low flows. And Denver Water isn’t the only entity allowed to take more water during the relaxation period. Other Western Slope reservoirs – Homestake, Eagle Park, Green Mountain and others – can be filled with water that would otherwise be going to Shoshone.
“Some of this is helpful for West Slope reservoirs,” Langenhuizen said. “Our reservoir at Wolford is able to fill because of this relaxation agreement. … We also get a big benefit from it.”
The River District is planning to purchase these crucial Shoshone water rights from Xcel for nearly $100 million. In November, the state water board approved the plan, which is now making its way through water court.
Who gets to control the Shoshone call was a point of contention between the River District and Front Range water providers during a September hearing, but Langenhuizen said that the River District intends to maintain the relaxation agreement if and when it takes over ownership of the water rights from Xcel, and to make those conditions permanent. The current agreement expires in 2032.
“We plan to carry this forward and bring those terms into the decree for Shoshone permanency,” Langenhuizen said.
This year’s dismal conditions mean there’s not enough water to go around and sharing it will require cooperation among the groups that use water from Colorado River and its tributaries.
“Unless we get significant precipitation, I think we’re going to be setting some records,” Langenhuizen said. “It’s going to take coordination this year between a lot of different water users to try and share what limited supplies we have. We’re starting to think about that.”
