Wyo preps for less water as drought creeps up Colorado River

Angus M. Thuermer Jr., WyoFile.com via Wyoming News Exchange
Posted 8/25/21

As federal water managers declared the first-ever official Colorado River water shortage last week, a top official said he’s confident Wyoming will responsibly implement its plans to store and divert even more flows from the troubled waterway.

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Wyo preps for less water as drought creeps up Colorado River


As federal water managers declared the first-ever official Colorado River water shortage last week, a top official said he’s confident Wyoming will responsibly implement its plans to store and divert even more flows from the troubled waterway.

The Department of the Interior on Aug. 16 said it would reduce water diversions to Arizona, Nevada and Mexico in 2022 after a scheduled August review set the restrictive sideboards for releases next year.

Despite that curtailment, Wyoming plans to corral another 115,000 acre-feet annually by building and modifying dams and their operations to potentially allow more diversions.

At the same time, Wyoming is fleshing out its Drought Contingency Plan and a “demand management” program that could see voluntary reductions in diversions before users in the state might be cut off. Wyoming doesn’t expect curtailments to happen next year, unless drought, aridification and climate change unexpectedly exacerbate the decline in Lake Powell.

In a press call announcing the downstream diversion reductions, a regional Bureau of Reclamation director appeared unfazed by the potential impacts of Wyoming’s dam-building plans.

“Wyoming has exercised foresight in the work of their Wyoming Water Development Commission,” said Wayne Pullan, the BOR’s director for the Upper Colorado River Basin, “and with our long history with Wyoming we’re confident that they’ll pursue any future projects responsibly, fully aware of the context of the hydrology and the difficulties on the Colorado River.”

Wyoming’s representative to the Upper Colorado River Commission, which will decide how any curtailments in Wyoming, Utah, Colorado and New Mexico will be borne, said his cohorts are “very concerned about the hydrology this basin faces.” A Drought Contingency Plan that’s been adopted in skeleton form “does provide the tools to help manage what we’re seeing now, as troubling as that is,” commission member Pat Tyrrell said at the press call.

Pullan would not comment on specific ongoing Wyoming projects, at least five of which in the Green River and Little Snake River basins would collectively control an additional 115,000 acre-feet at an estimated cost of $123 million. 

“It is worth noting that one of the purposes of the Colorado River storage project is to assist states, making use of their apportionment under the [1922 Colorado River] Compact,” Pullan said. Wyoming has not developed or appropriated its full share of the water entitled under that historic agreement, state officials have said.

The compact and apportionment among the seven states and Mexico, however, is based on an annual supply of at least 15 million acre-feet, an amount experts say the river basin no longer produces. Further, Wyoming believes the lower basin’s Arizona, Nevada, California and Mexico have historically overused their share while upper division states have not exploited their full rights.

At least one group has called for a moratorium on new storage or diversion projects in the basin until the seven states and Mexico can address what’s widely seen as claims to flows that no longer exist. Wyoming still deserves its share, state officials believe. 

“We aren’t obligated to sustain overuse anywhere else,” Tyrrell said in an interview, “to the detriment of our existing demands here in Wyoming.”

Tyrrell offered one scenario where an ongoing dam project could be immediately affected by less runoff. At the Big Sandy Dam in Sublette County, the Bureau of Reclamation is raising the structure to impound an additional 12,900 acre-feet for irrigation.

“That’ll come under a more recent priority date,” Tyrrell said, meaning the new storage area will be among the first to be cut off if lower-basin shortages creep upstream. The doctrine of prior appropriation that governs water use in Wyoming recognizes the first-in-time water appropriation to be first-in-right when shortages occur.

“If we are, for example, under any kind of curtailment,” Tyrrell said, Big Sandy “won’t be allowed to fill.

“It will put no more additional stress on the system if it’s not allowed to fill up,” he told WyoFile.

Other new dams, reservoir enlargements or operational changes that would give Wyoming access to more water would be subject to separate sideboards depending on whether they are built, what priority of appropriation they might impound, who owns them and other factors.

The amount of water involved in the Wyoming projects is “very small in comparison to Lake Powell,” Tyrrell said. Powell holds some 20 million acre-feet of what’s called active storage — the amount that can actually be used.

The downstream reductions — 18 percent, 7 percent and 5 percent of Arizona, Nevada and Mexico’s annual apportionments respectively — amount to 613,000 acre-feet. That’s about 3 percent of Powell’s storage or, seen another way, about 10 percent more than Wyoming’s average annual usage of basin flows.

The impact of any additional consumptive use in Wyoming — which could approach the 115,000 acre-feet contemplated in Wyoming’s dam plans — “is very, very small in comparison to what might be stored in Lake Powell,” Tyrrell said.

“I believe the environmental impact statement for Big Sandy found there would be no significant impact to reservoir elevations downstream by an enlargement,” he said.

Wyoming’s legal team stands behind water developers, assistant attorney general Chris Brown said as he echoed Tyrrell’s overview. “We are certainly not obligated to sustain overuse in other places in the basin on the backs of Wyoming water users, either current or future.”

Water developers, including Wyoming itself, understand the priority system and risks associated with constructing impoundments to hold back flows. In the face of dwindling supply, some wonder whether new structures might become stranded assets — facilities built under one scenario that can’t be used as intended in a new reality.

A professor of natural resources law at the University of Colorado Law School expressed skepticism about Wyoming’s basin-wide plans. “That seems like a bad investment,” Mark Squillace said in an interview.

Already the Bureau of Reclamation has activated provisions under its Drought Response Operations Agreement to release water from Flaming Gorge Reservoir in Wyoming and Utah. Pullan called the action a “small ‘e’” emergency release that will help keep the level at Powell high enough to continue generating valuable electricity.

The Flaming Gorge releases and others also help the four upper-basin states meet their water-flow obligations under the 1922 compact, Wyoming’s Tyrrell said. The dwindling flows, he said, “threaten to get worse.”

Another winter of meager snowfall, “could have really dramatic effects” on the 1,400-mile long river system, Tyrrell said. Two thin winters in a row — through spring of 2023 — and “we’re gonna see some real issues on Lake Powell,” which could have upstream ramifications.

“Unsatisfied demands are a situation with which the upper basin is very familiar,” Tyrrell said in the press call. “Discussions are underway to develop and finalize, if necessary, response plans for 2022.

“Typically, what we have to do [in shortage situations] is reduce consumption,” Tyrrell said. One key response element is demand management whereby reductions could be voluntary, possibly incentivized, before they are imposed. 

A pilot project in the Upper Green River basin several years ago could be a harbinger. It saw irrigators accept $200 an acre-foot to forego irrigation after they cut their season’s hay. The program saved 14,617 acre-feet in Wyoming one year while generating $2.2 million to users who temporarily gave up a portion of their annual diversions.

Municipalities and conservation groups funded the pilot program, which left two questions unanswered. One was whether the saved water was immediately diverted by another irrigator downstream or whether it flowed all the way to Lake Powell to accrue to Wyoming’s credit. The second was who would pay for a similar program should it be adopted during an actual crisis.

Some irrigators on the west side of the Upper Green River Basin regularly deal with less flows than they have rights to divert, Tyrrell said. Even during 2011, a year that saw spring flooding, irrigators didn’t get diversions the state had authorized, attorney Brown said.

“We still had a couple of our tributaries that were regulated back to the 1880s,” he said, meaning the state engineer cut off diversions for holders of water rights obtained later than that date.

Because of the regularity of shortages, the water division superintendent for the Upper Green River area ordered irrigators to install some 22 measuring devices on one creek as he sorted out various claims, Tyrrell said.

“Nobody believed him when they would go out and measure the flow,” Tyrrell said of the superintendent. “He said ‘well, you know, man, I’m going to invoke this authority and statute and require you to put in your own measuring device.’ 

“It raised holy hell for a few weeks,” Tyrrell said, “but they got it done.”

WyoFile is an independent nonprofit news organization focused on Wyoming people, places and policy.