A water fight is brewing in the West, and Wyoming water officials want to prepare for it with a study aimed at parsing and defining the state’s consumption from its Colorado River tributaries.

Anticipating a drier future and either voluntary or imposed restrictions, Wyoming should undertake a “conveyance-loss study,” Jason Mead, interim director of the Wyoming Water Development Office, told the state Water Development Commission on Oct. 6. The goal, State Engineer Brandon Gebhart told the WWDC, is to have a “defensible consumptive-use number to take to the other states,” when and if push comes to shove and Colorado River Basin water users face cuts to irrigation, industrial or municipal uses.

When Colorado River Basin water rights were divvied up starting in 1922, officials overestimated the amount of water the system would produce each year and ultimately promised more water to stakeholders than actually existed. Climate change, drought, shifting weather patterns and a population explosion in the region have exacerbated that initial over-subscription.

Further complicating the picture, the U.S. Bureau of Reclamation — the government’s Western water agency — admits there’s “an inability to exactly quantify these uses.” This “has led to various differences of opinion” regarding who gets to use how much water, the BOR states in a 2022 accounting of the river’s flows and uses.

As a result, the Colorado River and its tributaries — including Wyoming’s Green and Little Snake Rivers — do not have as much water as originally thought and apportioned. On top of that, the water that does flow can’t be precisely measured, and the 40 million people in the seven states and Mexico who rely on it haven’t agreed on how to resolve conflicting views on their rights to use what water there is.

“The Upper Basin and the Lower Basin have different opinions about that [downstream] obligation.”

Wyoming state water attorney Chris Brown

The goal of the conveyance-loss study is to pin down Wyoming’s consumptive use in case it needs to engage in those types of water rights’ conversations with other states.  

As a foundation to that study, Wyoming has “a pretty good handle on consumptive use of the crop,” Mead told the water commission. But the state is less certain about another key measurement — the loss from canals and ditches that carry the water diverted from rivers and streams to crops, and how those losses should be accounted for. Only some of those losses may be a debit to Wyoming’s share of the basin’s flows.

With the proposed study, Wyoming would be able to more precisely measure the differences between diverted flows and consumptive use.

That would allow the state to say “when we shut off a ditch … we’re actually saving this amount of consumptive use just along the ditch,” Gebhart told the WWDC. With such information at hand, “I think we could make a sensible argument that we would have to shut off less users.”

Ticking clock

Wyoming doesn’t expect potential curtailments any earlier than 2028, Gebhart told the Water Development Commission. Not all stakeholders agree with that timeline assessment, however, and say a “pinch point” in 2025 could prompt debate and conflict among states.

“The first pinch point [in 2025] raises the issue of the Upper Basin’s obligation to Mexico, if any, under the 1922 [Colorado River] Compact,” Chris Brown, a senior assistant attorney general in the Wyoming Attorney General’s office Water and Natural Resources Division wrote WyoFile.

Upper Colorado River basins. (The border of Wyoming and Colorado is mislabeled.) (U.S. BOR)

Mexico was not part of the 1922 compact, but the Mexican Water Treaty Act of 1944 granted that country 1.5 million acre-feet of Colorado River water annually. The compact and treaty are part of a suite of decrees, agreements and court decisions that make up what’s known as the Law of the River.

Regarding Mexico’s share, “the Upper Basin and the Lower Basin have different opinions about that obligation,” Brown wrote. That difference should be addressed before 2025 to “avoid a dispute” he stated.

“That does not mean we will curtail our water uses and, under current circumstances, we will not curtail when we reach that [2025] pinch point…” he wrote. “The difference of opinion itself will not result in a curtailment.”

Sen. Larry Hicks (R-Baggs), an influential water developer in the Little Snake River Basin, recommended the study, Mead and Gebhart said. It’s an “officially proposed project” Gebhard said, and will be discussed by the WWDC further in November with an eye toward securing funding, either from over-subscribed state water accounts, through a different appropriation from the Legislature or some other source.

The study’s first phase could be completed in 2025, after two irrigating seasons of research, officials said.

Pinning down losses

After water is diverted from a river or stream into conveyance systems of canals, ditches and pipes, some of it feeds crops. But leaks and seepage in those canals and ditches also results in loss. Water managers agree that some ditch losses return to “the system” that sustains a river’s flow.

Like “return flow” water that runs back into a river after flooding an irrigated field, conveyance losses that then return to the system shouldn’t count as a debit or depletion against Wyoming’s share of Colorado River Basin water, state officials say, and a study could help determine how much that is.

“Ditch losses that do return to the system (seepage), at some point, are not considered depletions because the water re-enters the stream,” Gebhart wrote in an email.

Some diverted water, however, doesn’t benefit a crop or return to the river and must be counted as a debit. “Losses from ditches that do not return to the system, at some point, are depletions, also known as consumptive use,” Gebhart stated.

These types of losses could be from evaporation, consumption by non-crop plants like willows, consumption by trees on the ditch bank, recharge to deep groundwater aquifers that don’t flow to the Colorado River and other, similar things, Gebhart wrote.

The loss from canals and ditches is only estimated today, and only by some irrigation districts. In a 2021 accounting by the WWDC, only half of the 157 irrigation districts, ditch and canal companies and other irrigation entities contacted by the agency responded.

An irrigation headgate on a canal in the Upper Green River Basin has a lock that can be used to regulate flows. (Angus M. Thuermer Jr./Wyofile)

Statewide, the survey estimates an average of 24% of the water that runs through the conveyance systems is lost. In the Green River and Little Snake drainages, estimates include as little as 0.5% for the Austin Wall Irrigation District on the Blacks Fork and 25% at the New Fork Irrigation District.

Many entities in the Green and Little Snake basins did not respond to the latest survey, including districts where water developers and irrigators want to spend millions of state dollars building or enlarging impoundments to aid irrigation and other uses.

Depletions, losses and consumptive uses 

Experts agree that more water is promised to Colorado River Basin water users than the system can actually deliver — essentially 7.5 million acre-feet annually each to the four Upper Division states and three Lower Division states, plus 1.5 million acre-feet to Mexico for a total of 16.5 million acre-feet. The calculation of available water on which the U.S. allocations were based in 1922 was flat-out wrong, many agree, and 23 recent years of drought coupled with climate change have left Lakes Powell and Mead at 28% of capacity, an historic low.

Now some experts say managers should anticipate only 9 million acre-feet annually system wide, according to proceedings at a September water seminar covered by Colorado Public Radio. That’s about three-quarters of what was used by all states, tribes and Mexico in 2021, CPR reported, and far short of the original 15 million acre-feet estimated in 1922.

If Wyoming faces curtailment or some other regulation in the Colorado River Basin, Gebhart said his office would need more staffers to monitor headgates and diversions. Today, a crew of six oversees more than 2,500 headgates in the basin, he said, and that might need to be increased to 36 or so.

Scrutiny by the state engineer is necessary because the 1922 compact prohibits Upper Division states from diminishing Colorado River flows at Lee Ferry, a gauge just below Lake Powell’s Glen Canyon Dam, below 7.5 million acre-feet annually on a running 10-year average. Wyoming is promised 14% of what’s left over to the Upper Division states.

From 2016-2020, the latest data available, a provisional U.S. Bureau of Reclamation report lists Wyoming’s average annual use at 421,000 acre-feet. Ranchers irrigated 305,800 acres in the Green and Little Snake River Basins in 2020, the report states. The population of those basins was 83,800, the BOR said.

At full supply — 7.5 million acre-feet available to the Upper Division states annually — Wyoming’s yearly portion amounts to a little over 1 million acre-feet, experts say. Should the Upper Division supply dwindle to 4 million acre-feet, under the Law of the River and 1944 Mexico treaty obligation, Wyoming would have rights to use only 553,000 acre-feet, according to a presentation by Gebhart’s office in Pinedale in September. In addition to Wyoming’s conveyance-loss study, Upper Division states want to use an up-to-date model to determine river flows and uses.

Angus M. Thuermer Jr.

Angus M. Thuermer Jr. is the natural resources reporter for WyoFile. He is a veteran Wyoming reporter and editor with more than 35 years experience in Wyoming. Contact him at angus@wyofile.com or (307)...

Dustin Bleizeffer

Dustin Bleizeffer is a Report for America Corps member covering energy and climate at WyoFile. He has worked as a coal miner, an oilfield mechanic, and for 22 years as a statewide reporter and editor primarily...

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  1. Once again WyoFile has seen fit to raise awareness of the water issue throughout the Upper and Lower Basin states that are dependent on the unreliable resource WATER. Thanks to Angus Thuermer and Dustin Bleizeffer.

  2. The indigenous peoples of the US have long been treated like the redheaded stepchild, so consequently breaking a treaty with any tribe will just go down as another treaty broken. Maybe time has come to “I” filed first and give some consideration to the well being of both the Upper and Lower States as well as the health of this blue ball we all call home. Meaningful comprehensive and truthful dialogue would held immensely in this fight looming on the horizon.

  3. We loose water whenever development occurs wait till they start filling abandonment on those lands up here in northern wyoming the bankers realtors and developers are doing all they can to detach the water and eliminate the ones who use it ,I know I sit on a board of control and have seen their bag of tricks this even includes the county commissioners .

  4. Another study upon study upon study. That is all politicians do We can’t act until the study is done. Which is seldom read. Problem all boils down to. Not enough supply for usage down stream. Face it. The Bank of water is over drawn.

  5. Irrigation conveyance losses have largely been ignored by irrigation districts, the Wyoming Water Development Commission, and the Wyoming SEO. The 24% loss estimate offered by the State is probably far too conservative. It’s time to start identifying and mitigating inefficient irrigation systems throughout Wyoming, not just in the Colorado River tributaries. Water shortages are just going to get more prominent. We have to try to get ahead of some of these challenges.

  6. THE GROWTH AIN’T HERE!! Deweys right about the expanding number of golf courses put in post 1922 but theres much more to it than that. Add in 10,000s of swimming pools in Las Vegas and Arizona, green lawns in the desert, 10,000s of acres of newly added irrigated crops in the arizona desert developed after the central Arizonz canal was constructed in 1986-1988, thousands of new subdivisions in the SW and rampant growth some of which is fueled by immigration. Wyoming needs to tabulate these growth numbers post 1922 and use the numbers to demonstrate we are not the problem. The lower Colorado states must be held accountable for their increased use of Colorado River water and not allowed to drag Wyoming into the equation. We must defend our irrigation industry by holding them accountable.

    1. Continued: How can the 1922 Colorado River compact and other agreements affect the Wyoming irrigators who have pre-1922 water rights?? It appears to me that they are grandfathered in as an existing appropriated use as of 1922. Almost all Wyoming bottom land including the Little Snake and Green River was homesteaded prior to 1922 and those homesteaders filed for early pre-1922 water rights most of which are pre 1900. Example, the Shoshones have a senior 1868 water right for 500,000 acre feet on the Wind River due to the treaty they entered at Fort Laramie in 1868 – first in time, first in right grandfathered use. In addition, the 4 state compact between Wyoming, Colorado, Kansas and Nebraska allowed for no new high capacity ground water wells on the Platte River drainage in Wyoming but existing pre 1999 wells were untouched. However, the State Engineers Office can declare a call on Platte River water during drought years and junior water right holders may be, and have been, cutoff – but this is a state action based on seniority of the water rights.
      So how can a 1922 Colorado River compact affect our early pre 1922 water right holders on the Little Snake and Green Rivers??? Their water rights greatly predate the thousands of golf courses, swimming pools, lawns, subdivisions, almond groves, etc. generated by unchecked growth in the SW. I feel our early water right holders are a senior use and are not subject to any upcoming restrictions on Colorado River water. Our State Engineer needs to vigorously defend our senior water rights and not give in to pressure from outside the state.

      1. Great research!!! Thank you!!!
        There will be a standoff.
        We can shut valves but they will demand water. Rational thinking will give way to hysterical demands and eventual cessation of civility. These elitists never take no for an answer.
        Expect a constitutional crisis when we say no. Guards at Flaming Gorge? Yes. Eventually.

      2. Lee, your question is a good one. Pre-Compact (essentially pre-1922) water rights can’t be affected. They are, in your terms, “grandfathered in.”

        Larry, I agree with the other commenter who thinks the map is correct as shown. I do too.

        Issues in the Colorado River Basin are very tough right now. Wyoming must remember 2 things, 1) to defend our water uses and water users, and our water future, and equally important, 2) we are part of a larger basin seeing things unseen before. So, decisions and alternatives may be before us that wouldn’t have been important 20 years ago. Every state and stakeholder has a position and an argument. The answer in 5 years may not be something we envision today.

        I don’t envy State Engineer Gebhart in the issues and decisions to come. But I have confidence in him and his Wyoming supporting team.

  7. colorado & california need water for their over-building their states.
    wyoming dose not need as much water since their are fewer people.
    therefore all water flowing down stream from wyoming will be confiscated by these consumer states.

    1. They will try. The Feds may attempt to force the issue, as they want to see a fight get literally bloody so they can create more unconstitutional fake laws to disarm the people. We are in grave times.

  8. This brings to mind a story of former senator Barry Goldwater addressing a colleague on the matter of western water resources: “ We value most three things in Arizona, our gold, our women, and our water. We will sell you our gold, you may marry our women, but we will kill you for our water”.

  9. So….
    The eggspurts were wrong.
    Nawwwww…. Really?
    Guessed wrong on supply.
    Guessed wrong on demand.
    Guessed wrong on dams.
    Guessed wrong on allocation.
    Eventually the flow will just stop.
    Then the water wars will get kinetic.
    Don’t be naive. California will demand the feds to take over our rivers. What then? Who would the criminals in DC side with? We must have a governor willing to stand up and a congressperson who isn’t a globalist snake. Go Harriet!

  10. Thanks for the informative article. Note the error in the BOR map, showing Utah extending well into Colorado. On a related note the Cheyenne City Council last night 10/24 spent some time talking about the CO River water supply in the context of the proposed gold mine 20 miles from downtown Cheyenne that is buying 1000 AF per year for 15 years from the Board of Public Utilities.

    1. @ Larry Wolfe:
      “Note the error in the BOR map, showing Utah extending well into Colorado.” Uhh, nope. Those are the correct borders, unless you’re possibly referring to some earlier territorial map.

  11. Senator Hicks is the director of the Little Snake River Conservation District, not a “water developer” in the commercial sense.

    1. When the answer from the report will support his dam then the moniker “water developer” fits. Larry is the study king while by passing/slowing/stalling water mitigation issues right now.

      For instance this statement: “These types of losses could be from evaporation, consumption by non-crop plants like willows, consumption by trees on the ditch bank, recharge to deep groundwater aquifers that don’t flow to the Colorado River and other, similar things, Gebhart wrote.”

      We could used nature to achieve some of these goals now by allowing Beavers to expand their range so water slows down in Wyoming and they naturally clear willows and Aspens. We over do the killing of nature instead of letting nature do a little more than it does now?

  12. Colorado River water conservation ? Start with the 200 golf courses in Greater Phoenix AZ and work your way back upstream from there …

  13. Great article.Head gate management by ditch riders is a joke. Too my dated knowledge the number of metered head gates in Wyoming, is one,
    The disagreements on return flow consumptive use is a nightmare and may never be solved.
    Good luck to Mexico and Tribal water right holders you are about to get screwed.

    1. If you go to the Wyoming State Engineer’s Website you can find the free data showing all of the monitored headgates, with the flow rates listed, under the “Realtime Streamflow Data” tab on the home page. There are also scans of most water rights records also free that can be searched easily under the “e-Permit” tab. There is a lot of information on what is being monitored and tracked.

  14. You’d better not wait till 2025. There is going to be a war. Water will be worth it’s weight in gold. The water users better learn the word SACRIFICE.

  15. This is a good lesson on why you should not quantify the amount of water leaving the state based on normal flows .

  16. I am amazed at the long history and complex nature of entitlements to the water of the Colorado river basin. This article’s coverage of these issues is excellent, as I have come to expect from your publication. You’re doing what you’re supposed to do, and you’re doing it very well.

    Samuel G. McKerall
    Lawyer
    Gulf Shores, Alabama