(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
"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
"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
*The State Engineer Pat Tyrrell speaks at the Sheridan Fulmer Library /