[1] Between 1911 and 1922, the Potomac River was repeatedly dredged by the United States Army Corps of Engineers to deepen the channel and alleviate flooding.

Dredged material was piled high on Columbia Island, helping to build it higher, lengthen and broaden it, and give it its current shape.

[2] An anonymous Corps of Engineers officer named the waterway between Columbia Island and Virginia the "Boundary Channel".

Boundary Channel was dredged and slightly widened in order to help provide this fill material.

[10] Due to silting and other issues, Boundary Channel is approximately 100 feet (30 m) wide as of 2013 (although the width varies).

On what was to be the new shoreline, the Army and its contractors built cement plants and marshalling areas for the deposit of sand and gravel.

The dike was then breached (and removed by dredge), allowing barges and other ships to deliver construction materials quickly and cheaply to the building site.

More than 1,000,000 cubic yards (760,000 m3) of earth and riverbottom were excavated, and Boundary Channel's lagoon enlarged by 30 acres (120,000 m2).

Virginia police found the nude body of 53-year-old Mrs. Margaret Fitzwater floating in the lagoon on the evening of September 24, 1944.

Within days, 60-year-old Gardner Tyler "Pop" Holmes, an eccentric who lived on a houseboat anchored in the lagoon, was charged with her murder.