A tremendous amount of rain falls on the state of Florida from north to south year after year. The average yearly rainfall for the entire state is about 51 inches, with greater amounts averaged in north Florida and south Florida. Central Florida receives the state average annual rainfall of about 51 inches. However, Florida’s landscape can absorb much more during tropical storms and hurricanes. The amount of water absorbed into Florida’s landscape is staggering on estimated absorption rates showing over 20 inches on a yearly average (4). In Florida, the ground confines water then holds it within a hydrogeological structured natural phenomenon called “aquifer systems”. Aquifers are crucial to Florida’s freshwater resources because they contain or hold the freshwater for drinking, agriculture, and industry for use as it is needed.
Gravity forces hydrogeological groundwater movement in an aquifer system. Under natural conditions, aquifer water moves “downhill” and sometimes reaches the land surface creating a spring or bubbling through the sand in a riverbed, lake or other wetland areas. The volume of water flowing through the aquifer is also dependent upon the porosity and permeability of the earthen materials in its boundary. In other words, water flows more quickly (2) if the voids or holes in the aquifer boundaries are large versus when these spaces are small.
Florida also boasts almost 8,000 temperate and subtropical bodies of water. This is the most in the Southeastern United States. (1) The state holds thousands of ponds, lakes, rivers, springs, and “ephemeral” or sinking water, the Everglades, and plenty of quicksand as well. In fact, Lake Okeechobee is Florida’s largest lake at about 683 square miles. That is larger than many counties in the state.
Florida Spring Magnitudes
The land surface of Florida does an incredible balancing act. Florida’s land mass is “floating” on a vast aquifer system (underground sea) of fresh water that runs in the (3) sub-surface from the Florida panhandle south to Miami. Aquifer water flows with an ebb and a tide cycle in aquifers following rainy patterns for aquifer recharge. The aquifer systems can be thousands of feet thick and maybe only a couple of feet in diameter while running horizontally for miles. The largest aquifers produce larger “artesian” springs and the way one measures a spring is by its volume flow rate.
Springs are measured in “magnitudes”, where “first” magnitude springs are the largest, “second” magnitude is second largest and so on. The magnitude of the spring relates to the volume of water being discharged from the spring opening every second. A first magnitude spring has a flow rate above 100 cubic feet per second. Florida officials recorded 300 “artesian” springs and 27 first magnitude springs (2). These two natural phenomena cannot be matched anywhere else in the United States. Researchers believe more “first magnitude” springs exist and yet to be recognized due to the nature of Florida’s karst landscape. Examples of Florida’s first magnitude springs are Silver Springs, Weeki Wachee Springs, and Kings Bay, the headwaters of Crystal River.
Crystal River’s headwaters form from first magnitude springs where I learned to scuba dive as a youth. The primary spring opening is forming Kings Bay with crystal clear aquifer water to a depth of about fifty feet. The bay itself is teeming with life including large amounts flora and fauna. Crystal River is also a sanctuary for herds of manatee there to enjoy the warmth offered by the spring in the winter months. The average temperature of the water flowing out of the spring opening is about 72 degrees F every day, winter or not.
Another interesting statistic is that spring’s flow rate is directly related to the recharge rate from Florida’s aquifers systems that are based on average yearly rainfall amounts in the “spring sheds” or watersheds local to the spring in question. When all counts are totaled, Florida springs produce higher water volumes than anywhere else on Earth. The deepest and largest first magnitude spring and aquifer systems discovered thus far are located in north Florida, near Tallahassee.
Florida’s springs and their related ecosystems are unique and cannot be recreated by man, that gives them tremendous ecological value. Many of Florida’s springs are coastal and create streams and rivers to the Gulf of Mexico or the Atlantic Ocean. These ecosystems are unique to the entire world and contain a diverse population of aquatic life and life dependent on marine life. (4) This includes marine species living in fresh, brackish, and saltwater.
Interestingly, springs cannot be owned by individuals or industry if the spring is accessible by adjacent public waterways (4). However, Florida’s phosphate industry strip mines many of these eco-sensitive areas every day. Florida law, in this case, is blurred at best because the state of Florida issues permits to the phosphate industry to strip mine the landscape in these unique ecosystems. Where is the balance between public and industry water use?
1. DEP – (Florida Department of Environmental Protection)
2. Learn about Springs in West Central Florida. (swfwmd.state.fl.us)
3. Sinkhole Information. (lakecountyfl.gov)
4. Water Quantity and Policy in Florida. (srwqis.tamu.edu)