The United States Supreme Court recently issued a unanimous opinion on a procedural matter that will have a significant impact on future Clean Water Act litigation. In National Association of Manufacturers v. Department of Defense, issued on January 22, 2018, the Court determined that challenges to the Waters of the United States Rule must be filed in federal district court rather than filed directly with the federal courts of appeal. When the Waters of the United States Rule was issued, approximately thirteen separate challenges were filed in district courts around the country. As a precaution, a number of challenges were also filed directly with the federal courts of appeal. When the Sixth Circuit Court of Appeals determined that it had original jurisdiction over challenges to the Rule, the individual district court cases were stayed or dismissed. Before the Supreme Court, the government relied on two provisions in the Clean Water Act to support the Court of Appeal’s determination. While noting that such an outcome would promote efficiency, the unanimous Court rejected the government’s interpretation of the statute based on the language of the statute. In rejecting the government’s position, the Court cleared the way for the separate district court challenges to resume and raised the likelihood of conflicting rulings in jurisdictions across the nation. The Court’s ruling will also complicate efforts by the current Administration to replace the Waters of the United States Rule, as opponents will now be able to file multiple challenges to any replacement rule in multiple favorable jurisdictions.