During Hurricane Sandy the seas rose a record 14-feet in lower Manhattan. Water flooded city streets, subways, tunnels and even sewage treatment plants. It is unclear how much sewage may have been released as plants lost power or were forced to divert untreated wastewater into the Hudson River. Four days after Sandy, the environmental group Riverkeeper attempted to measure the storm’s effect on water quality. If the river had been widely contaminated, by then, any evidence had washed out to sea. A week later, Sandy was followed by a more typical nor’easter. Andrew Juhl, a microbiologist at Columbia University’s Lamont-Doherty Earth Observatory, joined Riverkeeper the next morning to test the waters again. He and Riverkeeper captain John Lipscomb were curious to see what mark both storms had left.