In the early nineteen-sixties, a young lawyer named William Ruckelshaus was assigned to Indiana’s state board of health to prosecute cases of toxic dumping. At the time, it was commonplace for manufacturers to discard untreated industrial swill—ammonia, cyanide, pesticides, petroleum waste, slag from steel plants, “pickle liquor” (sulfuric acid)—into the nearest sewer, river, or lake. Sometimes, it formed piles of noxious froth nearly as tall as a house. “Those rivers were cesspools,” Ruckelshaus told me recently. He and his colleague Gerald Hansler, an environmental engineer, began touring the state in a white panel truck. They collected water samples and snapped photographs of fish corpses—bluegills, sunfish, and perch, poisoned by the effluent that gushed from industrial outfalls. Then they wrote up the evidence and brought charges against those responsible. Yet, however diligently they worked, their efforts were often regarded with suspicion by Indiana’s governor, who wanted to keep businesses from moving to states with even laxer environmental standards. “I just saw how powerless the states were to act,” Ruckelshaus recalled.