Unfortunately, due to the water quality, it is still not recommended to swim in the Anacostia or Potomac Rivers in Washington but the water quality of both rivers has been steadily improving and there is a study to examine creating a public swimming area along the Anacostia by 2025.
With global warming, giving residents a place to cool off during periods of excessive heat is going to become an important public health issue. There was one recent study that found the hottest parts of DC to be 17 degrees warmer than the coolest location in DC on certain days.
Could We Be Swimming In D.C.’s Rivers Soon?
https://dcist.com/story/19/07/23/cou...s-rivers-soon/
https://static1.squarespace.com/stat...inal+LoRes.pdf