Giant Springs is a large first magnitude spring located near Great Falls, Montana and is the central feature of Giant Springs State Park. Its water has a constant temperature of 54°F and originates from snowmelt in the Little Belt Mountains, 60mi away. According to chlorofluorocarbon dating, the water takes 50 years to travel underground before returning to the surface at the springs according to the placard at the state park.Giant Springs is formed by an opening in a part of the Madison aquifer, a vast aquifer underlying 5 U.S. States and 3 Canadian Provinces. The conduit between the mountains and the spring is the geological stratum found in parts of the northwest United States called the Madison Limestone. Although some of the underground water from the Little Belt Mountains escapes to form Giant Springs, some stays underground and continues flowing, joining sources from losing streams in the Black Hills, Big Horn Mountains and other areas. The aquifer eventually surfaces in Canada. Giant Springs has an average discharge of 242cuft of water per second or 150 million gallons per day.