On May 2, 2011, the US Supreme Court ruled in the case of Montana v. Wyoming, finding for the state of Wyoming with a vote of 7-1 in a case that involved the states' relative water rights over the Tongue and Powder rivers. Montana claimed Wyoming violated the Yellowstone River Compact, which allowed water storage facilities to be constructed. In October 2008, the Court appointed a special master to oversee the lawsuit because the Supreme Court has original and exclusive jurisdiction over all disputes between US states. The investigator initially reported that Montana had failed to state a valid claim in its lawsuit because the activities of Wyoming were permissible under the Compact. Justice Thomas wrote the majority opinion for the Court and Justice Kagan took no part in the decision.
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