This is the March 1999 edition of National Geographic that contains an article on the springs of north (and central) Florida.
Florida is home to one of the largest concentrations of natural freshwater springs in the world. Many of its springs are some of the most massive in volume of water produced.
Spring flow is measured in cubic feet per second (cfs) in the US and the largest springs are “first magnatude springs” with flows of 100 cfs (2600 liters per second) or more. Currently, Florida has about 27 first magnatude springs, several producing much more than the 100 cfs.