The Tidal Basin is a partially man-made reservoir between the Potomac River and the Washington Channel in Washington, D.C. It is part of West Potomac Park and is a focal point of the National Cherry Blossom Festival held each spring. The Jefferson Memorial, the Martin Luther King, Jr. National Memorial, the Franklin Delano Roosevelt Memorial, and the George Mason Memorial are situated adjacent to the Tidal Basin. The basin covers an area of about and is deep.HistoryThe concept of the Tidal Basin originated in the 1880s to serve both as a visual centerpiece and as a means for flushing the Washington Channel, a harbor separated from the Potomac River by fill lands where East Potomac Park is situated. Peter Conover Hains, an engineering officer in the U.S. Army, oversaw the design and construction. The basin was initially named Twining Lake, in honor of Major William Johnson Twining (U.S. Army Corps of Engineers), Washington DC's first Engineer Commissioner. According to testimony given to a Congressional subcommittee in 1917, it was Major Twining's idea to create a tidal reservoir and use that water to help "flush" the Washington Channel, and the design was carried out by Colonel Hains. A 1917 Army Corps of Engineers map of Washington already shows the basin with the name "Twining Lake". The Tidal Basin which exists today was not laid out until after World War II. It was built in 1949 by the construction firm of Alexander and Repass, which was unusual at that time because Alexander was of African descent and Repass was of European descent.