Montana v. Wyoming and North Dakota

RESPONDENT:Wyoming and North Dakota
LOCATION: 81st U.S. Congress

DECIDED BY: Roberts Court (2010-2016)

CITATION: 563 US 368 (2011)
ARGUED: Jan 10, 2011
DECIDED: May 02, 2011

Peter Kenneth Michael – Senior Assistant Attorney General of Wyoming, for the defendant
Steve Bullock – Attorney General of Montana, for the plaintiff
William M. Jay – Assistant to the Solicitor General, Department of Justice, for the United States as amicus curiae, supporting the defendants

Facts of the case

1950, Montana, Wyoming and North Dakota signed the Yellowstone River Compact, which spelled out how the states would share water. In 2007, Montana sued Wyoming, alleging farmers and other water users along the Powder and Tongue rivers were being harmed by Wyoming’s excessive water use. Attorneys for Wyoming argued that much of the water used by the state’s residents and businesses was not covered by the 1950 agreement.

Special Master Barton Thompson issued an interim report, finding that Montana had grounds to sue over Wyoming’s expanded use of water since 1950. However, Thompson rejected Montana’s claim that Wyoming should be held liable for increased water use due to irrigation improvements. Meanwhile, North Dakota, also a member of the Yellowstone compact, was named as a second defendant in the original lawsuit. But Montana officials have said its inclusion was a formality and that they have no disagreement with their eastern neighbor.


Has Wyoming violated the Yellowstone River Compact by leaving less water in the river for Montana’s uses?

Media for Montana v. Wyoming and North Dakota

Audio Transcription for Oral Argument – January 10, 2011 in Montana v. Wyoming and North Dakota

Audio Transcription for Opinion Announcement – May 02, 2011 in Montana v. Wyoming and North Dakota

Clarence Thomas:

This case comes to us under our original jurisdiction.

With Congress’s consent, Montana and Wyoming agreed to the Yellowstone River Pact in 1951.

Under this Pact, the States agreed that water rights existing in each State as of 1950 would continue to be enjoyed in accordance with the doctrine of appropriation.

In 2008, Montana sued Wyoming alleging that it had breached the Compact in several ways by using more than its agreed upon share of the water.

Only one of Montana’s allegations is before us today.

The claim that by installing more efficient sprinkler irrigation systems, Wyoming water users have reduced their runoff.

As a result, less water returns to the river and less water reaches Montana than it did in 1950.

Montana claims that Wyoming has therefore violated the Compact.

The Special Master reappointed found that Montana’s allegations failed to state a claim.

Montana filed an exception.

In an opinion filed with the clerk today, we overrule Montana’s exception to the Special Master’s Report.

The Yellowstone River Compact preserves water rights “in accordance with the laws governing the acquisition and use of water under the doctrine of appropriation”.

Under that doctrine, efficient sprinkler, irrigation systems are permissible even if they cause a net increase in water consumption.

This is true so long as the sprinkler users do not increase the amount of water they divert from the river or use the conserved water to irrigate new acreage.

Accordingly, Montana’s allegations that Wyoming has violated the Compact by merely allowing the installation of more efficient sprinkler systems fails to state a claim.

Justice Scalia has filed a dissenting opinion.

Justice Kagan took no part in the consideration or decision of this case.