State Engineer: Montana could call its senior Tongue River water rights again this spring

(Sheridan, Wyo.) — Last spring, Montana cited superior water rights on the Tongue River, and for six weeks lasting from April to June, called upon Wyoming to curtail any unauthorized use, free river use and post-1950s water rights on the Tongue. The legal dispute is both historical and ongoing—in 2007, the State of Montana filed for leave with the U.S. Supreme Court to sue the State of Wyoming over alleged violations of the Yellowstone River Compact, according to the Rocky Mountain Mineral Law Foundation . The Compact was entered into by Montana, Wyoming, and North Dakota in 1950 to equitably divide and apportion the waters of the Yellowstone River system. The Compact allows each state to use the appropriative rights existing as of January 1, 1950, and then allocates unappropriated water between the states. It was last spring that Montana placed a "call" on Wyoming's usage of water from the Tongue River. According to a University of Colorado Water Rights Dictionary , a call is set to communicate the level of demand on the available supply of natural stream flow. A call is often required when a water right holder feels they are not receiving all of the water they are entitled to, and when asking other users shut down (curtail) upstream water rights junior to them, until their senior right is satisfied. "Clearly this was a result of deteriorating hydrology, or what wasn't very good snowpack. As we all remember, late April, May and June became very rainy, at least on the Wyoming side of the border ... We got enough eventually to fill the reservoir," Pat Tyrrell, Wyoming State Engineer told a crowd at the Sheridan County Fulmer Library at a Wyoming Water Update meeting Wednesday. "We are going to go back and revisit what went on last year, and what we are setting up for this year," Tyrrell said. "Many of you know, in the Tongue River Basin, and the Powder River Basin, we are not that shiny in terms of snowpack." On May 21, 2015, Tongue River Reservoir filled and the call ended. But this year, there is even less snowpack—meaning less springtime water—in the region. "Our snowpack is, instead of 10 inches, you are looking at six inches right about now. So 40% less snow than we had last year, for the whole basin," Tyrrell said. "Do we expect a call from Montana this year? ... I would not be surprised." *The State Engineer Pat Tyrrell speaks at the Sheridan Fulmer Library /