WST–Scotus-Yellowsto

The U.S. Supreme Court on Tuesday said Montana can pursue its lawsuit that charges Wyoming with using too much water from a pair of rivers that flow between the states.

Montana argues Wyoming’s agricultural and energy industries are depleting the Tongue and Powder rivers at the expense of downstream residents in Montana. In a complaint filed last year, Montana asked the court to order Wyoming to leave more water in the rivers and award damages and other relief. It did not specify amounts.

Wyoming officials dispute the charge, saying both states are suffering due to a prolonged drought.

Reed Benson, a water law specialist at the University of Wyoming, said the Supreme Court’s acceptance of the case marks a victory for Montana – but only a small one.

“This is an important step in favor of Montana, but it is really very preliminary,” Benson said. “Montana still has a pretty high hill to climb as the complaining state.”

Tuesday’s order also allowed Wyoming 45 days to file a motion to dismiss the lawsuit.

That means the case could be decided more quickly than previously expected, possibly avoiding the need for a court-appointed “special master” – essentially a hearing officer – to oversee proceedings.

Both sides have welcomed the chance to make their case directly to the court. That could avoid the substantial expense of a drawn-out legal battle.

“The court will decide whose interpretation is right before we go into a factual dispute,” said Montana Attorney General Mike McGrath. “It will allow a more rapid and potentially less expensive resolution.”

At the heart of the disagreement are the states’ different interpretations of the Yellowstone River Compact. The 1950 agreement spelled out how states were to share water from the Tongue, Powder and other rivers within the Yellowstone River basin.

Wyoming officials say they are adhering to the compact and that the drought has meant less water for both states.

But Montana says Wyoming is storing more water in reservoirs than the compact permits and is allowing excessive pumping of underground water reserves that feed into the two rivers.

Those “groundwater” reserves are tapped by some Wyoming farmers to irrigate their fields. Energy companies use large volumes of groundwater during production of coal-bed methane, a type of natural gas.

In 2004 and again in 2006, Montana called on Wyoming to increase flows in the two rivers but was denied.

Wyoming said in response that Montana had failed to show it was harmed by Wyoming’s water use.