Columbia Island is an island located in the Potomac River in Washington, D.C., in the United States. It formed naturally as an extension of Analostan Island in the latter part of the 1800s, and over time erosion and flooding severed it from Analostan. The U.S. federal government deposited material dredged from the Potomac River on the island between 1911 and 1922, and again from 1925 to 1927. The island was also reshaped by the government at this time. It received the name "Columbia Island" about 1918. In 1968, the island was renamed Lady Bird Johnson Park. Located within the park are the Lyndon Baines Johnson Memorial Grove, Navy – Merchant Marine Memorial, and the Columbia Island Marina. The island, park, memorials, and marina are part of the George Washington Memorial Parkway and administered by the National Park Service.Early formation of Columbia IslandColumbia Island is in part natural, and in part man-made. Columbia Island did not exist in 1818 and at that time, Analostan Island (now known as Theodore Roosevelt Island) was largely rock and quite close to the D.C. shoreline. Due to deforestation and increased agricultural use upstream, the river eroded much of the northern bank and widened the gap between Analostan Island and the shore and simultaneously large deposits of silt built up around Analostan Island. By 1838, Analostan had almost doubled in length toward the south and by 1884, the new southern part of Analostan Island was defined and built up, and supported a well-established wetland. However, the river gradually eroded the center of Analostan Island, severing Columbia Island from its parent body.