On April 28, the U.S. Court of Appeals for the First Circuit, sitting en banc, overturned its own 30-year-old precedent on the Clean Water Act (CWA), North & South Rivers Watershed Ass’n v. Town of Scituate, 949 F.2d 552 (1st Cir. 1991). Under Town of Scituate, “diligent prosecution” of a federal administrative enforcement…