 However, according to the National Park Service, although there were significant Dakota settlements in the area surrounding the Mississippi-Minnesota confluence, there is little evidence that the spring area itself was used as a sacred site.The camp was explored by early European settlers who were in the process of building Fort Snelling.On May 5, 1820, Lieutenant Colonel Henry Leavenworth moved his troops to the area because their former encampment, on the Minnesota River, was causing unhealthy conditions.