Reservoir-release pilot project in Colorado begins this week to test possible compact call
Beginning Wednesday, Front Range water providers will release water stored in Homestake Reservoir in an effort to test how they could get water downstream to the state line in the event of a Colorado River Compact call.
Aurora Water, Colorado Springs Utilities and Pueblo Board of Water Works will each release 600 acre-feet from Homestake Reservoir, which is near the town Red Cliff, for a total of 1,800 acre-feet that will flow down Homestake Creek to the Eagle River and the Colorado River.
The release, scheduled to take place Wednesday through Sept. 30, will produce additional flows ramping up to 175 cubic feet per second.
That amount of water represents less than 0.3% of current systemwide storage for Colorado Springs Utilities and less than 0.4% of Aurora’s storage, according to a news release from Aurora Water.
The Front Range Water Council, an informal group made up of representatives from Front Range urban water providers and chaired by Denver Water CEO Jim Lochhead, approached the state engineer about running the experiment.
“The Front Range Water Council is, of course, concerned about what’s going on on the Colorado River in terms of climate change and the flows and compact compliance issues,” said Alexandra Davis, deputy director for water resources at Aurora Water. “We thought it would be helpful to do a pilot project to test some of those authorities and administration capabilities with the state engineer.”
The utilities are releasing water downstream that would have otherwise been sent to the Front Range in a water-collection system known as a transmountain diversion.
A compact call could occur if the upper basin states (Colorado, Wyoming, Utah and New Mexico) can’t deliver the 7.5 million acre-feet of water per year to the lower basin states (Arizona, California and Nevada), as required by a nearly century-old binding agreement. This could trigger an interstate legal quagmire, a scenario that water managers desperately want to avoid.
A compact-call scenario could be especially problematic for Front Range water providers since most of their rights that let them divert water over the Continental Divide from the Western Slope date to after the 1922 Colorado River Compact. Many Western Slope consumptive water rights date to before the compact, so they are exempt from involuntary cutbacks under a compact call. That means those cutback obligations could fall more heavily on the post-compact water rights of Front Range water providers.
The goal of the pilot project is to see how the water could be shepherded downstream to the state line. Division of Water Resources engineers will have to make sure senior water rights holders don’t divert the extra water. Water commissioners are visiting dozens of irrigation headgates on the Eagle River to ensure this doesn’t happen, said Division 5 engineer Alan Martellaro.
“We will see how much work and time and pre-planning it is going to take to make sure these ditches don’t pick up the water,” he said.
But even with shepherding, it’s unlikely the entire 1,800 acre-feet will make it to the state line because of this year’s dry conditions. Water managers expect to see transit losses in the form of evaporation and thirsty riparian vegetation along the riverbanks sucking up the water. That’s OK because this year’s dry conditions could mimic the conditions that water managers would expect to see in a year with a compact call.
“Not coincidentally, if there’s a need to do this for compact administration in the future years, it’s probably going to be under dry conditions,” said Colorado State Engineer Kevin Rein.
Figuring out how much water actually makes it to Utah is one of the main questions this experiment will try to answer.
“That’s the perfect question to give validity to this pilot,” Rein said. “We will have a better answer for you on that after the pilot is done.”
Water managers will be closely monitoring stream gauges to track the release as it flows downstream. Martellaro estimates it will take the water about four days to get from the headwaters of Homestake Creek to the state line west of Grand Junction.
The release will be a big boost for streamflows in Homestake Creek and the Eagle River, which was running at 15 cfs near Red Cliff on Tuesday afternoon, according to the U.S. Geological Survey stream gauge. The Colorado River near Glenwood will rise from Tuesday’s reading of 1,920 cfs.
The release will begin at 9 a.m. Wednesday with an additional 25 cfs coming out of Homestake Dam and slowly ramp up to 175 cfs, reaching that level by Wednesday afternoon. It will stay there until Monday morning, then ramp down slowly over the final two days to keep fish from being stranded in side pools, Martellaro said. According to Greg Baker of Aurora Water Public Relations, streamflows will still be below spring runoff levels and there’s no concern about flooding.
The reservoir release also could have implications for a potential demand-management program, the feasibility of which the state is currently investigating. At the heart of a demand-management program is a reduction in water use on a temporary, voluntary and compensated basis in an effort to send as much as 500,000 acre-feet of water downstream to Lake Powell to bolster water levels in the giant reservoir and, indirectly, to meet Colorado River Compact obligations.
Under such a program, agricultural operators could get paid to leave more water in the river, but the program stirs fears of Front Range water providers throwing money at the problem without having to reduce their own consumption, while Western Slope fields are fallowed.
Responding to those concerns, Denver Water’s Lochhead has said his agency would participate in a demand-management program by using “wet water.”
This week’s Homestake release is an example of how Front Range water providers could send water stored in Western Slope reservoirs downstream under a demand-management program.
“What we are trying to do is help the state engineer gather options and thinks through how these might operate in practice, which might be helpful to the state of Colorado,” said Pat Wells, general manager for water resources and demand management at Colorado Springs Utilities.
Aspen Journalism is a local, nonprofit, investigative news organization covering water and rivers in collaboration with The Aspen Times and other Swift Communications newspapers. For more, go to aspenjournalism.org.
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