Montana is suing Wyoming in the Supreme Court over water rights in two shared rivers, which Montana says are running dry because of Wyoming’s overuse. The lawsuit is over the Tongue and Powder Rivers, which flow from northeastern Wyoming into southeastern Montana. The lawsuit marks a sharp escalation in the water fight between the states. The lawsuit claims that Wyoming is ignoring Montana’s “senior” water rights by taking more water from the rivers than allowed under the 1950 Yellowstone River Compact. The compact calls for disagreements to go straight to the Supreme Court for resolution.