But something did go wrong. In addition to the damage to the watershed, where the utility has elsewhere spent billions of dollars to keep out sewage, Maryland’s C&O Canal spent nearly two months functioning as a jury-rigged open-air sewer to bypass the collapse and has been coated in human muck several inches deep. If the collapse had occurred a few miles upstream, it would have contaminated the intake of the Washington Aqueduct, cutting off the water supply for about 1 million people.