 The Corps of Engineers largely blocked the flow of the Anacostia River to the west of Kingman Island, creating the lake (although some water is permitted to enter the lake to prevent it from completely evaporating and to refresh its waters).Kingman Lake is currently managed by the National Park Service.Prior to the arrival of European settlers in the 18th century, the Anacostia River was a fast-flowing and relatively silt-free river with very few mudflats or marshes.