Alley Spring State Park, Mo. 2004

Alley Spring has an average daily flow of 81 million gallons and holds the record for the largest credible measured flow of any Ozark spring (2750 cfs or 1.776 billion gallons of water, on April 22, 1974). In 1893, George McCaskill built the present mill with a steel turbine as power source.
See 2005 pictures here.
It was a state park from until in 1969 when the people of Missouri donated it, along with Round and Big Spring State Parks to the National Park Service to become a part of the Ozark National Scenic Riverways. A gift from Missouri to America.