Overlooked for many years as an enforcement tool, the doctrine of federal common law of water pollution rocketed to national prominence following the Supreme Court's historic decision in Illinois v. City of Milwaukee.¹ Although the Court declined to exercise its original jurisdiction over the allegation by Illinois that Milwaukee caused a public nuisance by its discharge of raw sewage into Lake Michigan, it did hold that the word "laws" in the federal question statute, §1331(a),² embraces federal court-created common law. It also found that federal district courts have jurisdiction to entertain claims by states (and perhaps others) that a defendant's discharges into "interstate or navigable waters" create a public nuisance.