Click the link to read the article on the Big Pivots website (Allen Best):

January 28, 2025

It’s part of a theme. Does Colorado need to start planning for potential Colorado River curtailments?

Snow in southwestern Colorado has been scarce this winter. Archuleta County recently had a grass fire. A store manager at Terry’s Ace Hardware in Pagosa Springs tells me half as many snowblowers have been sold this winter despite new state rebates knocking 30% off the price of electric models.

Near Durango, snowplows normally used at a subdivision located at 8,000 feet remain unused. At Chapman Hill, the in-town ski area, all snow remains artificial, and it’s not enough to cover all the slopes. A little natural snow would help, but none is in the forecast.

Snow may yet arrive. Examining data collected on Wolf Creek Pass since 1936, the Pagosa Sun’s Josh Kurz found several winters that procrastinated until February. Even when snow arrived, though, the winter-end totals were far below average.

All this suggests another subpar runoff in the San Juan and Animas rivers. They contribute to Lake Powell, one of two big water bank accounts on the Colorado River. When I visited the reservoir in May 2022, water levels were dropping rapidly. The manager of Glen Canyon Dam pointed to a ledge below us that had been underwater since the mid-1960s. It had emerged only a few weeks before my visit.

That ledge at Powell was covered again after an above-average runoff in 2023. The reservoir has recovered to 35% of capacity.

Will reservoir levels stay that high? Probably not, and that is a significant problem. Delegates who wrangled the Colorado River Compact in a lodge near Santa Fe in 1922 understood drought, at least somewhat. They did not contemplate the global warming now underway.

In apportioning the river flows, they also assumed an average 17.5 million acre-feet at Lee Ferry, the dividing line between the upper and lower basins. It’s a few miles downstream from Glen Canyon Dam and upstream from the Grand Canyon. Even during the 20^th century the river was rarely that generous. This century it has become stingy, with average annual flows of 12.5 million acre-feet. Some worry that continued warming during coming decades may further cause declines to 9.5 million acre-feet.

Colorado State University’s Brad Udall and other scientists contend half of declining flows should be understood as resulting from warming temperatures. A 2024 study predicts droughts with the severity that formerly occurred once in 1,000 years will by mid-century become 1-in-60 year events.

How will the seven basin states share this diminished river? Viewpoints differ so dramatically that delegates from the upper- and lower-basin states loathed sharing space during an annual meeting in Las Vegas as had been their custom. Legal saber-rattling abounds. A critical issue is an ambiguous clause in the compact about releases of water downstream to Arizona and hence Nevada and California.

Might Colorado need to curtail its diversions from the Colorado River? That would be painful. Roughly half the water for cities along the Front Range, where 88% of Coloradans live, comes from the Colorado River and its tributaries. Transmountain diversions augment agriculture water in the South Platte and Arkansas River valleys. The vast majority of those water rights were adjudicated after the compact of 1922 and hence would be vulnerable to curtailment. Many water districts on the Western Slope also have water rights junior to the compact.

In Grand Junction last September, Andy Mueller, the general manager of the Colorado River Water Conservation District, the primary water policy agency for 15 of Western Slope counties, made the case that Colorado should plan for compact curtailments — just in case. The district had earlier sent a letter to Jason Ullmann, the state water engineer, asking him to please get moving with compact curtailment rules.

Eric Kuhn, Mueller’s predecessor at the district, who is now semi-retired, made the case for compact curtailment planning in the Spring 2024 issue of Colorado Environmental Law Review. Kuhn’s piece runs 15,000 words, all of them necessary to sort through the tangled complexities. Central is the compact clause that specifies the upper basin states must not cause the flow at Lee Ferry, just below today’s Glen Canyon Dam, to be depleted below an aggregate of 75 million acre-feet on a rolling 10-years basis.

That threshold has not yet been met — yet. Kuhn describes a “recipe for disaster” if it is. He foresees those with agriculture rights on the Western Slope being called upon to surrender rights. He and Mueller argue for precautionary planning. That planning “could be contentious,” Kuhn concedes, but the “advantages of being prepared for the consequences of a compact curtailment outweigh the concern.”

Last October, after Mueller’s remarks in Grand Junction, I solicited statements from Colorado state government. The Polis administration said it would be premature to plan compact curtailment. The two largest single transmountain diverters of Colorado River Water, Denver Water and Northern Water, concurred.

Recently, I talked with Jim Lochhead. For 25 years he represented Colorado and its water users in interstate Colorado River matters. He ran the state’s Department of Natural Resources for four years in the 1990s and, ending in 2023, wrapped up 13 years as chief executive of Denver Water. Lochhead, who stressed that he spoke only for himself, similarly sees compact curtailment planning as premature.

“It just doesn’t make sense to go through that political brain damage until we really have to,” he said. “Hopefully we won’t have to, because (the upper and lower basins) will come up with a solution.”

Lochhead does believe that a negotiated solution remains possible, despite the surly words of recent years…

“We need to figure out ways to negotiate an essentially shared sacrifice for how we’re going to manage the system, so it can be sustainable into the future,” he said. This, he says, will take cooperation that so far has been absent, at least in public, and it will also take money.

Instead, we’ll have to slog along. The runoff in the Colorado River currently is predicted to be 81% of average. It fits with a theme. Unlike the children of Lake Wobegone, most runoffs in the 21^st century have been below average.