Formerly owned by the Federal government, the August A. Busch Conservation Area was purchased in his memory by his widow Alice Busch in 1947. I had always thought it was much older, and the government had requisitioned it during the war. There are still bunkers left over from the war (and in other parts of the region) where TNT was stored. Weldon Spring, where nuclear weaponry was processed, is nearby.
While there are lakes carved out of the terrain, there are also lakes formed by earthen dams, such as the one below.