BILLINGS, Mont. — The U.S. Supreme Court ruled Monday that Wyoming farmers are not taking too much water from a river system they share with neighboring Montana.
The high court turned away Montana’s complaint that Wyoming was violating a 1950 agreement between the states by depleting water from the Tongue and Powder rivers. Montana had claimed in 2007 that more efficient irrigation techniques in Wyoming prevented runoff from rejoining the rivers and flowing downstream.
The ruling is not expected to resolve some of the non-agriculture aspects of the case, including a sharp increase in the amount of water used during oil and gas exploration in Wyoming. As a result, the broader question of Wyoming’s overall water use remains in dispute.
Justice Clarence Thomas wrote Monday’s 7-1 decision. It said more efficient irrigation is permissible even if it comes at the detriment of downstream users.
Modern irrigation systems that use sprinklers allow farmers to increase crop yields by applying water directly to crops, rather than flooding entire fields. In the case of the Tongue and Powder rivers, that means less water is left over for Montana.
But justices determined Montana’s loss does not mean Wyoming is doing anything wrong. Thomas compared improved irrigation methods with the recapture of water so it can be used more than once — a practice that has been upheld by the Montana Supreme Court.
“By using sprinklers rather than flood irrigation, those water users effectively recapture water,” Thomas wrote. “They are simply different mechanisms for increasing the volume of water available to the crops, without changing the amount of diversion.”
Justice Antonin Scalia was the only dissenting vote. Justice Elena Kagan did not participate in the case because she worked on it while in the solicitor general’s office.
The case is Montana v. Wyoming and North Dakota, 137 Orig.
Scalia wrote in his dissent that Montana was merely trying to protect its rights under the 1950 agreement — not seeking a precise volume of water every year. The question is not how much water is diverted from the rivers but how much is depleted from the overall water supply, Scalia wrote.
He added that his colleagues disregarded the text of 1950 agreement and instead substituted their own “none-too-confident reading” of common law.
A court-appointed special master had rejected part of Montana’s claim last year. Stanford University law professor Barton Thompson Jr. agreed with Wyoming attorneys who argued that the case came down to how much water was being taken out of the Tongue and Powder rivers, not what happens to the water after that.
In October, the court ruled that Montana has raised a valid issue with its lawsuit and rejected Wyoming’s attempt to dismiss the case.
Remaining aspects of the lawsuit could have consequences for Wyoming’s natural gas industry. Over the last decade, companies seeking a type of gas known as coal-bed methane have pumped billions of gallons of water from underground aquifers shared by the two states.
Montana contends the companies are draining water that would otherwise feed the Tongue and Powder rivers. A Texas-based energy company, Anadarko Petroleum Corp., attempted to intervene in the case but was denied.
North Dakota is also listed as a defendant because it is a party to the Yellowstone Compact. However, no claims have been made against it and the outcome of the lawsuit is likely to have little bearing on the state.