Brenda and I rode the trike 130 miles today, going to Mammoth Spring, Arkansas, near the Missouri border. It was 104 degrees F, but the water from the spring was a cool 58 degrees! The spring generates over 9 million gallons of water EVERY HOUR! Mammoth Spring State Park, where Mammoth Spring produces over 9,000,000 gallons of water each hour, creating the Spring River. The spring at its origin creates a large pool. This dam was built in 1887 to generate electricity, but the power company is no longer active here. Water flows over the dam at the same rate of 9,000,000 gallons per hour.