Our rivers are not plumbing

Three large cities conducted an experiment near the small town of Red Cliff last fall. The Homestake Reservoir released a burst of water at the behest of the Pueblo, Colorado Springs, and Aurora water companies. Their goal was simple: to follow a 500-acre blob of water from the reservoir as it flowed to the Colorado state border.

The results of the experiment were alarming. The subsequent report, released this month, is a reminder this Earth Day that our Western Slope rivers – some of the most intensively managed and measured in the world – are not the same as plumbing. They are wild, complex and continue to baffle our models and controls.

Homestake Reservoir is one of the state’s many trans mountain detours. The artificial lake collects water from the Eagle River watershed. Pipes and tunnels send that water under the Continental Divide and into the Arkansas River near Leadville. Once in the Arkansas River, further diversions bring that water to the Front Range.

But water managers used Homestake to steer the water’s eruption in the other direction, through the Eagle River into the Colorado River. Then they watched the gauges closely to see if the water reached Utah, an exercise called “water shepherd” in the jargon of the field.

But by the time the Homestake water reached the stateline, state engineers couldn’t determine how much of the water completed the journey.

This conclusion should open our eyes to the uncertainty climate change poses for the Gunnison Valley and the rest of the Western Slope. If we can’t use our reservoirs to direct water downstream with any precision, our prospects for quenching the thirst of downstream states look bleak.

The basis of much of our water management and the reason for conducting the Homestake experiment is the 1922 Colorado River Compact. The agreement between southwestern states requires Colorado to send a minimal amount of water downstream to Nevada, California and Arizona. If we don’t meet that goal, federal reservoirs like Blue Mesa would be used to release more water. But we assumed that in the 1950s and 1960s (when we destroyed thousands of acres of farmland in the construction of Blue Mesa Reservoir, one of the world’s largest trout fisheries drowned the towns of Iola and Sapinero and destroyed half of the Gunnison sage ). the best habitat of the black grouse) that we could get the water from point A to point B.

The Homestake experiment shows that we are unable to deliver a certain amount of water downstream. We don’t know how to guarantee a certain amount of water will flow downstream to Nevada, California and Arizona.

For example, if the Upper Gunnison River Basin were called upon to widen the Colorado River downstream, it would be “extremely difficult to track or quantify the supply,” said Frank Kugel, former General Manager of the Upper Gunnison River Water Conservancy District.

It would be a “gigantic task,” Kugel told me. The resulting higher river levels would cause more water to flow through head doors and onto hay fields. Dry soils along the Gunnison and Taylor rivers would absorb some of the water. And then the three reservoirs and dams (Blue Mesa, Crystal, Morrow Point) in the Aspinall unit would further cloud the picture. And that’s all before the Gunnison tunnel would lead hundreds of cubic feet per second into the Uncompahgre River Valley.

To detect only the supply of water, let alone measure it, would require a very large release from the Upper Gunnison basin, Kugel told me.

Both Kugel and Sonja Chavez, the current general manager of the Upper Gunnison River Water Conservancy District, told me that the difficulties of water management contribute to their skepticism of “ demand management ” – a huge effort by Colorado water managers to determine how to best to reduce water use.

“The whole issue of herding hats is huge,” Chavez said. Demand management may sound good on paper, but the legal and water shepherd implications cast doubt on the implementation of a state-wide demand management program.

“The ability to track conserved water up to the state line is really critical to the success of that program,” Andy Mueller, Colorado River District general manager, told Aspen Journalism on the topic of the Homestake experiment. “And if you can’t track a 1,600 acre-feet of water snail to the state line, how are you going to follow the voluntary reduction in the use of a small ditch on the West Slope that they might save as much as 15 acre-feet?”

Water shepherd experiments will continue as the state needs to figure out how to deliver more water downstream. Colorado has set its sights on storing 500,000 acre-feet of water in Lake Powell to protect against the increasingly likely scenario of too little water flowing into Nevada, California and Arizona. But as the Upper Gunnison River Water Conservancy District’s delivery report for this week shows, that 500,000-acre-foot buffer may not be enough. Lake Powell will release approximately 8 million acre feet this year. Only about 5 million acre feet is expected to flow in.

“Tossing down 500,000 acre feet won’t do much if it stays warm and dry and if the flows don’t materialize,” Chavez said.

The next time you drive past Blue Mesa Reservoir, this news could put its waters in a different light. We don’t know how to supply water through rivers, but we do know how to contain them. And since Lake Powell is expected to fill only 33% of capacity this year, our limited knowledge may not be enough.

(Sam Liebl can be contacted at 970.641.1414 or [email protected])

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