"If the Potomac River has gotten more attention than the Anacostia in the past 50 years, it’s partly because the Potomac supplies 90 percent of the region’s drinking water. That amounts to an average of 486 million gallons a day, according to the Potomac Conservancy. The Potomac watershed, which includes 14,670 miles of land that drains to the river, covers parts of West Virginia, Pennsylvania, the District, Maryland and Virginia. In the 1950s, reports of stench and dangerous levels of pollution clouded the Potomac’s reputation. But the 383-mile river wasn’t always in such bad shape."
"In 1608, Capt. John Smith described the Potomac and Anacostia rivers as being full of wildlife. More than 300 years later, a 1914 Public Health Service study found the Potomac in 'generally good condition' with 'ample oxygen.'
But things soon went downhill. The Interstate Commission on the Potomac River Basin reported that the District’s raw and partially treated sewage doubled between 1932 and 1956. And in 1965, President Lyndon B. Johnson declared the river a 'national disgrace.'"
Megan Buerger reports for the Washington Post May 2, 2012.