Springs occur when water pressure causes a natural flow of groundwater onto the earth's surface. As rain filters down into the Floridan aquifer system, natural acids in the rainwater slowly dissolve the aquifer's limestone. This can cause large cracks, cavities and tunnels through which groundwater flows.
As rainwater enters or "recharges" the aquifer, pressure is placed on the water already present. This pressure moves water through the cracks and tunnels within the aquifer, and sometimes this water flows out naturally to the surface at places called springs.
When the openings are large, spring flow may become the source of rivers such as the Ichetucknee and the Wacissa. During droughts, flow from springs make up a large portion of the lower Suwannee and Santa Fe river flows.
When rivers flood, the pressure created by rising floodwaters causes many springs to reverse flow. Falmouth Spring in Suwannee County is one spring which does this regularly.
Not really. The water source for a spring can vary. Some springs are fed by shallow groundwater seepage out of the soil, others are fed by deep aquifer water discharged under artesian pressure. These differences influence the hydrology and the water chemistry of springs.
Springs can be categorized in a number of ways, with the two main ones being discharge (the amount of water flow out of the spring) and spring water chemistry.
The German hydrologist O. Meinzer developed a spring classification based on the average annual discharge of a spring. Called the spring magnitude, this remains one of the most common ways of describing the "size" of a spring. The categories are:
Note: "cfs" = cubic feet per second
100 cfs = 64.6 million gallons per day
Different springs exhibit different water chemistry, based mainly on the geologic setting of the spring.
Most springs in the Suwannee River Basin are of the calcium bicarbonate type. A few springs (Suwannee Springs, Steinhatchee Springs, Hampton Springs) are of the mixed water quality type.
The District has conducted water chemistry sampling in many springs throughout the region. The reports "Springs of the Suwannee River Basin in Florida" (PDF, 16.4MB) and "Springs of the Aucilla, Coastal, and Waccasassa Basins in Florida" (PDF, 1.7MB) provide a wealth of data on spring water quality.