Photo by AlbinoFlea

As part of a recently released 20-year sustainability plan, Mayor Vince Gray said he was optimistic that by 2032 D.C. residents won’t only be able to swim in the Potomac River, but that they’ll also be able fish safely from it. But a new report finds that the Potomac—which winds 383 miles from West Virginia into D.C, Virginia and Maryland—is the nation’s most endangered waterway.

According to the report published today by American Rivers, the Potomac “is threatened by agricultural and urban pollution,” so much so that it beats out the Green River, Chattahoochee River, Missouri River, and Hoback River for the dubious distinction.

The Potomac—which provides roughly 90 percent of the region’s drinking water, some 486 million gallons per day—is especially vulnerable because of storm-water runoff and combined sewer overflows and pollutants like pharmaceuticals and personal-care products. It is additionally threatened by rollbacks of the Clean Water Act, says the report:

For thirty years, the Clean Water Act was interpreted to protect all waters from headwater streams to mighty rivers. However, protections for these waters have been called into question by two Supreme Court decisions, leaving more than 5,000 public drinking water sources across the country vulnerable. If small stream and wetland protections are reversed, an estimated 10,000 miles of the Potomac River watershed will be in danger.

In addition, efforts in Congress to roll back safeguards under the Clean Water Act have been consistent and relentless. Without these fundamental protections, pollution in the Potomac will endanger drinking water, the health of fishermen and boaters, and fish and wildlife.

In 2010, the Potomac Conservancy published a report in which it argued that the region needs more forests and grasslands to soak up the rainwater that flushes pollution into the river. Pollution has gotten so bad that intersex fish have been found in the river—bass that have both male and female reproductive organs.

This isn’t the first time that the Potomac has been cited for pollution problems—in 1965 President Lyndon B. Johnson called it a “national disgrace.”