On every spring node, you might have noticed a designation for "magnitude" of that spring. It's one of the factors I take into consideration for designating a spring major, minor, or limited access. I have to admit though, even years into making this site I had no idea what it meant! I keep looking it up for reference, so I figured, why not post it here!
The magnitude of a spring isn't arbitrary or subjective in any way; it's actually a measurement of the output of water in cubic feet per second (ft3/s). Here are the official measurement ranges for each corresponding magnitude:
- 1st Magnitude: 100+ ft³/s
- 2nd Magnitude: 10 - 100 ft³/s
- 3rd Magnitude: 1 - 10 ft³/s
- 4th Magnitude: 100 gal/min - 1 ft³/s
- 5th Magnitude: 10 gal/min - 100 gal/min
- 6th Magnitude: 1 gal/min - 10 gal/min
- 7th Magnitude: 1 pint/min - 1 gal/min
- 8th Magnitude: <1 pint/min
These measurements were first used by Oscar Edward Meinzer in 1927 in Large Springs in the United States and has been used for every update of the Springs of Florida publication (which has been an invaluable resource to this site), including the 1947 edition (Ferguson et al.) and the 1977 edition (Rosenau et al.).
I use this primarily to tell if the spring is worth seeing in-person. Magnitudes 3-8 are generally the viewing springs, while 1-2 are generally going to be the swimming springs. It's not a hard rule by any means; in fact, many 3rd magnitude springs are very nice swimming holes. It's just one piece of the puzzle. The more you know!