Giant Springs was founded during the Lewis and Clark expedition of the Louisana Purchase in 1805. Giant Springs is a large first magnitude spring with an average discharge of 242 cubic feet of water per second or 156 million gallons per day. The spring has a constant temperature of 54F° year around. The water originates from snowmelt in the Little Belt Mountains 60 miles away and according to radioisotope dating takes almost 2,900 years to travel underground before returning to the surface at the springs. The spring is the headwaters of the world's shortest river, the Roe River which is 200 feet long and flows into the Missouri river.