The mud flats and marshland to the west of the
Washington Monument (on the left side of this image) were called the Potomac Flats for most of the 1800s. In 1870, the Army Corps of Engineers began
dredging the Potomac to remove silt and to deepen the ship channel to improve access to Washington by water. Dredged material was dumped onto the tidal flats along the Washington waterfront. The work continued until August 30, 1911, when contractors had moved over 12 million cubic yards of material from the
river to create East and West Potomac Parks and the
Tidal Basin.