Golden Gate University Environmental Law Journal


In 2007, Montana filed an original action with the United States Supreme Court asserting that certain water uses in Wyoming violated the Yellowstone River Compact (“Compact”). The litigation was triggered by severe drought in the basin between 2000 and 2006, during which period there was inadequate water available for Montana appropriators in the Tongue River and Powder River sub-basins. Montana raised four primary issues: irrigation of new acreage in Wyoming; new and expanded storage facilities; new groundwater pumping, especially associated with coalbed methane development; and increased consumption of water due to improved irrigation efficiency on existing irrigated acreage. In 2011, the U.S. Supreme Court decided the first substantive issue in this litigation: “Is a switch to more efficient irrigation with less return flow within the extent of Wyoming’s pre-1950 users’ existing appropriative rights, or is it an improper enlargement of that right to the detriment of Montana’s pre-1950 water users?” The Court held that such improvements are permitted under the Compact.

This Article takes a careful look at this decision. It begins with an introduction to the physical setting, focusing on the Tongue and Powder sub-basins within the Yellowstone basin. It discusses Montana’s arguments why the Compact precludes improved irrigation efficiency that increases consumption and the Special Master’s rejection of those arguments. Next, the Article looks at the U.S. Supreme Court’s opinion. Finally, it offers some observations triggered by this litigation, critiques the doctrine of recapture in western water law, and supports the Court’s embrace of water use efficiency over protection of the status quo. We begin with a look at the Yellowstone River basin.