On June 13, 2013, the U.S. Supreme Court unanimously upheld lower court rulings in Tarrant Regional Water District v. Hermann, holding that Oklahoma water laws validly barred the export of state water. The petitioner in the case is the Tarrant Regional Water District; the appellees are officers of the Oklahoma Water Resources Board and the Oklahoma Water Conservation Storage Commission. 

The litigation centered on the conflict between Oklahoma statutes regarding water use which, among other things, prevents Oklahoma state entities from selling water for out-of-state use, and the Red River Compact among Oklahoma, Texas, Arkansas and Louisiana, which allocates the water in the Red River Basin among those states and was ratified by the U.S. Congress in 1980.

The petitioners sought a judgment declaring that the certain Oklahoma statutes violated the Commerce and Supremacy Clauses of the U.S. Constitution, and an injunction to prevent application of the Oklahoma statutes. Both the trial court and the 10th Circuit dismissed petitioner’s claims. In the opinion, the Supreme Court upheld the lower courts, finding that the Oklahoma statutes are not preempted by the Red River Compact.