Progressive Review, 2005 - We have established a swamp squad whose job it will be to reduce the epidemic of press mentions of Washington once having been a swamp-filled town. The first violator apprehended by this squad is Ann Gerhart of the Washington Post who, in the course of a crudely chipper Style article on Bush's war against the civil services, describes its founding in 1883 adding that it "built Washington, helping to transform a swampy, mosquito-infested river town into a colossus of power."
Not only is there no evidence that the 19th century civil service drained any swamps or sprayed DDT within them, the swamps didn't even exist. Those places were marshes, typical of river shorelines, and precisely the sort of setting people who call Washington "swampy" pay large sums of money to put their weekend condo next to or contribute to environmental groups to save elsewhere around the country.
These legends seem to be promulgated mainly by those who believe that Washington didn't amount to much until they got here. We also suspect that those from New York City are heavily to blame, having to find something else derogatory about Washington once it got some bagel shops. Our position has always been that a city that has to brag about its bagels doesn't have much going for it.
For the record, one way you tell a swamp from a marsh is that the former has trees as in Pogo's Okeefenoke Swamp. There was nothing like that in DC.