When Cheyenne’s municipal water board approved a deal in October to supply up to 14,500 acre-feet of water over 15 years for a proposed gold mine west of town, attorneys insisted on inserting a clause in the contract. It retained the right to cut water deliveries if the city itself has to curtail its water use due to the Colorado River crisis.

“The majority of our water comes from the Colorado River [basin] and if that call [requiring upstream users to cut consumption] comes in, we’re in big trouble,” Cheyenne Mayor Patrick Collins said.

About 70% of the city’s municipal water supply originates 150 miles west in the Little Snake River drainage, a part of the Colorado River Basin. A complex “trans-basin” system of pumps, tunnels and pipelines transports the water under the Continental Divide in the Medicine Bow Routt National Forest to the city. 

Cheyenne’s legal claims to the Colorado River Basin water were appropriated from 1954 to 1982 — making it a relatively new user in the system. If there is a curtailment, it would be applied to the newest or most “junior” appropriations, then work back in time to the 1922 Colorado River Compact. That means, depending on how far back in time a curtailment extends, 70% of the city’s water supply could be shut off — an action that could come as soon as 2028 if hydrological conditions keep trending for the worse, according to the Wyoming State Engineer’s office.

This map depicts Cheyenne’s municipal water supply system, which funnels in water from the Little Snake River Basin. (Cheyenne Board of Public Utilities)

“If we lose 100% of our Colorado River Compact water, we’re upside down,” Collins said, adding that about 80,000 people rely on the city’s municipal water system. “We wouldn’t have enough water to meet our current needs.”

For now, Cheyenne, Baggs, Rock Springs, Green River, Pinedale and a handful of other towns that depend on water from the Little Snake and Green River basins in Wyoming are assessing where they stand in the pecking order of appropriated water rights in the event of a curtailment. Although municipalities make up a small percentage of Wyoming water users under the Colorado River Compact and associated laws, their legal claims to the water are among the most vulnerable.

First in time, first in right

If the Upper Colorado River Basin Commission issues a curtailment for Wyoming, it would not necessarily force all water users subject to the compact to close their spigots completely.

There’s no curtailment priority in terms of use — whether it’s irrigation for cattle and alfalfa fields, water consumed for cooling at the Jim Bridger coal-fired power plant or water piped to homes for domestic use. Instead, a curtailment would be applied based on the first-in-time, first-in-right water appropriations doctrine: Those who gained their water appropriation latest in time would be the first ordered to shut off their water.

For example, if the state had to curtail 100,000 acre-feet of water — approximately one-sixth of its annual Colorado River Basin consumptive water use — the state engineer would begin with the newest appropriations and work back in time until the 100,000 acre-feet of consumptive water use curtailment was met.

Shauna Gray and her dog, Lula Mae, paddle at Rob Roy Reservoir July 31, 2022. The reservoir is part of a trans-basin water system that supplies water to Cheyenne. (Dustin Bleizeffer/WyoFile)

If, let’s say, that required turning off all Colorado River Basin water appropriations back to 1970, that would choke off all water appropriated since then — whether for industrial, municipal or agricultural use. The cities of Rock Springs and Green River, which share a municipal water system that serves some 39,000 residents, would lose access to 75% of their Green River water appropriation. The towns would still be allowed to tap the 4,343-acre-feet-per-year appropriation they secured in 1928 and the 2,895-acre-feet-per-year appropriation that predates the 1922 compact. The rest — 75% — was appropriated in 1971 and after.

This type of variable vulnerability applies to many Colorado River Basin water users with appropriated rights that were obtained at different times. The exact order for how a curtailment would be applied is well documented and under continual review, according to the state engineer’s office.

Small straw, big vulnerability

Agriculture accounts for 83.7% of Wyoming’s consumptive use of water in the Colorado River system, according to the SEO. Municipal water use accounts for about 2.8% — or 3.3% if you include rural domestic water use. Industry — trona facilities, coal power plants, oil and natural gas processing — make up most of the remaining 13%.

Approximately 70% of agricultural irrigation water rights in Wyoming were appropriated before 1922. Those pre-1922 appropriations are not subject to the Colorado River Compact and cannot be shut off under a curtailment. The pre-1922 protection applies to all Colorado River Basin water users.

A majority of Colorado River Basin water appropriations held by Wyoming municipal water authorities, however, are post-1922. That means some 125,000 urban Wyoming residents and businesses are vulnerable to a curtailment.

“If we lose 100% of our Colorado River Compact water, we’re upside down. We wouldn’t have enough water to meet our current needs.”

Cheyenne Mayor Patrick Collins

Given the curtailment clause in Cheyenne’s water contract, gold mine developer Gold King Corp. is shopping around to secure alternative water resources, according to Mayor Collins. The city of Cheyenne — as well as Green River, Rock Springs and others — are doing the same.

“There is the possibility that we would not be able to collect any water from the Little Snake System if [a] curtailment call goes below 1954,” Cheyenne Board of Public Utilities Administrator Brad Brooks told WyoFile. “We are looking for additional water to mitigate this possibility and planning for the worst case that our Little Snake water will not be available.”

Green River and Rock Springs are in the same boat. Their joint municipal water system collects 100% of its water from the Green River and its tributaries to serve some 39,000 residents in and around the two cities. Only 10% of their Colorado River Basin water appropriations pre-date the 1922 compact.

Green River. (Google Earth)

Although the cities don’t rely on the full volume of their legal claims to Colorado River Basin water, the time to plan for supplemental water sources is now; 2028, the year Wyoming might first see a curtailment, isn’t far away, Green River/Rock Springs Joint Powers Board General Manager Bryan Seppie said.

“Understand, [a curtailment] probably isn’t a one-year event,” Seppie told WyoFile, adding that much depends on what Mother Nature has in store. “We’ve got to secure other water resources to serve as replacement water if [a curtailment] were to happen. Conservation is a tool, but with these types of curtailments, conservation is not going to get you out of it.”

Backup water

Part of the Gold King deal provides Cheyenne’s Board of Public Utilities approximately $5 million in fees that would help cover the cost to expand Cheyenne’s groundwater capacity. The city’s water board is also seeking up to $10.5 million in grants from the Wyoming Water Development Commission for its Borie wellfield expansion project. The expansion would add approximately 3,300 acre-feet of water per year to the city’s water portfolio, according to the board. 

That would boost Cheyenne’s non-Colorado River Compact water source portfolio to 9,900 acre-feet per year. But the city would still be in trouble in the event of a curtailment because its average annual use is about 14,000 acre-feet.

“We are actively pursuing possibilities” for additional water resources, Brooks of the city’s BOPU said.

Anglers try their luck on the Green River at Seedskadee National Wildlife Refuge on Sept. 27, 2022. (Dustin Bleizeffer/WyoFile)

Expanding groundwater capacity, however, isn’t an affordable option for Rock Springs and Green River, according to Seppie. Instead, the cities are looking to those in the state with pre-1922 appropriations to share some water.

The federal System Conservation Program pays water users to curb consumption. Congress recently re-appropriated funding for the program, while the Inflation Reduction Act includes some $4 billion for efforts to modernize Colorado River Basin infrastructure and water management practices. Another $8.3 billion from the bipartisan Infrastructure law is available to address water and drought challenges throughout the U.S.

The SCP is an attractive option, Seppie said, for both ag irrigators and municipalities. Ag irrigators who volunteer for the program can use payments to upgrade their irrigation systems to waste less water.

“It’s a voluntary thing. It’s preemptive, and it’s benefiting the entire system,” Seppie said. “We haven’t gotten to a point where we’re having those discussions [with city officials]. But we have somewhat of a timeframe; 2028 is not all that far off.”

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 25 years as a statewide reporter and editor primarily...

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  1. Now is the time, before a crisis leads to price-gouging, for municipalities to start entering into fallowing and conservation agreements with Wyoming agricultural districts. It’s possible to go out and start tapping other water sources, but establishing a framework that allows cities to pay farmers for water when curtailments come is typically cheaper and better for all involved. California has been paying for conservation and rotational fallowing with its Colorado River water agricultural districts since the 1980s to ensure that its cities (and junior rights holders) continue to have water despite cutbacks.

    1. california also has easy access to the pacific ocean.
      easily able to build desalination plants,
      which have been part of the united states
      navy for the last 50 years.
      but doesn’t seem good enough for the over-industrialized
      dilettantes that populate california.

  2. Good article, Dustin. In many ways, you identified the critical issues for Wyoming. I appreciate both Mayor Collins’ and Director Brooks’ description of where Cheyenne stands on this important issue. And no, the “blue” states cannot confiscate all water from Wyoming. Can’t happen. Do we have obligations to other states under our Compacts and Court Decrees? Yes, in every corner of the state – these are equitable agreements. Can they take away all our water? Absolutely not. Don’t get dragged down that rabbit hole.

  3. Good news that our pre 1922 water right holders are grandfathered in – thats the way it should be. Cheyenne will almost be forced to target the Ogallala aquifer in Laramie County which will meet resistance from senior ground water right holders as we saw in the recent high capacity irrigation well case. And, the Ogallala is a finite aquifer – it recharges at an extremely low rate and is regarded by some as a fossil aquifer going back to the Miocene era. Incredible amount of water compounded behind the large dams in South Dakota – this is Missouri river water – its used primarily for hydro-electric purposes with very little municipal or irrigation use. However, the Mississippi River desperately needs this water right now as barge traffic is severely restricted due to decreased flows. The National Geographic magazine ran a feature article on the Ogallala aquifer sometime back which is an excellent source of information for Laramie County and Cheyenne.

    1. Continued: Hundreds of 40 acre parcels of land were created by subdividing larger tracts of ag land in Laramie County. Most of these housing development parcels sourced there water from the Ogallala – the withdrawal rate from stock water and housing use is low compared to high capacity wells – the SEO defines these wells as 25 gpm or less. Should Cheyenne seek high capacity municipal water from the Ogallala it would threaten these wells and all of the ag wells irrigating from the Ogallala – and the fight would be on – again.

  4. Seems like fighting words! The Green River’s waters which originate in Wyoming could possibly be restricted to the cities and industries of Sweetwater County? The entire population, agriculture and industry are not even a speck of water use compared to anything downstream. Industry and growth will be halted in Wyoming but not in Arizona, Nevada and California? Water rights are meaningless and we should continue to take the necessary allotment regardless of what the federal government tries to mandate. They are already going to empty Flaming Gorge and Fontenelle Reservoirs. We are upstream just take it.

  5. It’s been said that water doesn’t run downhill, it runs toward money.
    That may have been tongue-in-cheek but there is some truth in it.
    The eastern slopes of Wyoming need to pay attention to what is happening as well.
    This is especially true of communities that use surface water as their main supply and don’t have territorial dated water rights.

  6. wyoming is about to have it pocket picked by blue states.

    as only 1 of 2 states left that are red,utah being the other state
    the blue sates with their allies in the congress are about to confiscate all water from

    these blues states will tell wyoming to reclaim yellowstone lake for their water use.
    off course treating the water for potability will be the responsibility of wyoming

    1. This is not a “blue vs red” situation. This is an over population problem with no solution! Except a die off of millions of humans

      1. Guess John missed that 3.3% of the water goes to munis and other domestic use. Big over population problem in Wyoming. Riiight. Seriously, are there not legal grounds for temporary assignments and transfers among licensed users? Calls on junior muni license holders could be mitigated by setting up contracts ahead of time with senior or pre-1922 appropriations for use in case of cutoffs. Depends on infrastructure to accommodate such transfers, but there are likely innovative ways to exchange molecules of water where cost/price differentials warrant.

      2. You are right as to the issue. But the people won’t “die off.” They will move away to places that do have water, however unwillingly. Humans are not trapped in any ecosystem in Wyoming.