 With the re-opening of Fort Snelling during the Civil War, Coldwater Spring was once again used to supply water to the fort.In the 1880s, the Army built a formal waterworks at the site, including the extant spring house and reservoir.Following the closing of Fort Snelling after World War II, the site was turned over to the United States Bureau of Mines as their Twin Cities Research Center, where mining research was carried out for over 40 years.