Fifty years ago, Congress voted to override President Richard Nixon’s veto of the Clean Water Act. It has proved to be one of the most transformative environmental laws ever enacted.

At the time of the law’s passage, hundreds of millions of gallons of raw sewage was dumped by New York City into the Hudson River every day. This filth was compounded by industrial contaminants emptied into the river along much of its length. The catch basin for all of this was New York Harbor, which resembled an open sewer. At its worst, 10 feet of raw human waste blanketed portions of the harbor bottom, and certain reaches held little or no oxygen to sustain the life of its fishery. Trash floated among oil slicks.

Health advisories against eating fish from the Hudson remain, but its ecology has largely recovered, thanks to the law, which imposed strict regulations on what could be discharged into the water by sewage treatment plants, factories and other sources of pollution. Today people swim in organized events in New York Harbor, which […]