Where the Yellowstone goes in this case is likely through the Supreme Court.
Montana and Wyoming have been in a legal battle since 2007 over the 1950 Yellowstone River Compact, an agreement that divided available flow from the river and its tributaries among Montana, Wyoming and North Dakota.
Montana is claiming that new irrigation methods in Wyoming result in less water in the river for downstram users. Wyoming argues the compact only controls how much water can be diverted, not how much water can be consumed. The dispute is likely headed to the Supreme Court.
LINK (via: New West)