Many coastal springs in the Southwest Florida Water Management District lie in or near the fresh-water /salt-water transition zone, which is a brackish zone in the Floridan aquifer where seaward-moving fresh water meets landward-moving salt water. As a result of their proximity to the coastal transition zone, some springs discharge brackish water. Homosassa and Chassahowitzka Springs are good examples of brackish-water springs. Brackish ground-water discharge indicates that sea water from the Gulf of Mexico is present in the aquifer gulfward of and below the springs.
Homosassa Springs Park headquarters
It is estimated that springs in the Southwest Florida Water Management District (SWFWMD) discharge more than 1,600,000,000 gallons per day of ground water from the Floridan aquifer. Prior to development, spring flow in the region accounted for 80% of the ground-water discharge from the Floridan aquifer. However, as development has occurred this percentage has decreased.
Ground-water discharge from the Floridan aquifer is important to springs in the region for several reasons: 1) it provides the springs with adequate ground-water supplies to maintain flow; 2) it is an important component of many aquatic and terrestrial ecosystems throughout the region; and 3) it is an ideal barometer by which to gauge the water quality of the Floridan aquifer over large areas (tens to hundreds of square miles). Springs throughout the SWFWMD exhibit seasonality in discharge as rainfall recharges the Floridan aquifer inland of the springs. This recharge causes water levels in the aquifer to rise and spring discharge to increase. Studies by the US Geological Survey have shown that spring flow along the coast of Citrus and Hernando Counties can vary considerably during the year. A number of other springs throughout the SWFWMD exhibit similar variations in discharge as well, with lowest flows occurring late in the dry season (May/June) and highest flows occurring late in the wet season (Sept./Oct.)
The Homosassa Springs group lies in western Citrus County approximately three miles south of King’s Bay and one mile southwest of the intersection of S.R. 490A and U.S. Hwy 19. The spring group is composed of the main spring, which includes three large vents contained within a collapsed-cavern feature, and many smaller secondary vents spread over an area of nearly four square miles. The Homosassa River originates at the main springs and receives additional flow from the spring-fed Southeast Fork of the Homosassa River and the spring-fed Hall’s River. Springs in the Homosassa Springs group include Homosassa Main Spring #1, #2, and #3, Trotter Main, Pumphouse, Hidden River Head, and Hall’s River Head Spring.
Homosassa Springs group aerial view
The average annual discharge of the springs in the Homosassa Springs group is approximately 229,000,000 gallons per day. Ground water discharging the Homosassa Springs group may be fresh or brackish, depending on tides and water levels in the Floridan aquifer. At low tide, water quality varies across the spring group with total dissolved solids (TDS) concentrations increasing from less than 250 mg/l along the southeastern fork of the Homosassa River to greater than 1,500 mg/l in springs at the head of Hall’s River. Chloride concentrations across the group may range from less than 50 mg/l to greater than 500 mg/l, indicating that water quality at the spring group is strongly influenced by the coastal transition zone even at low tide. Nitrate concentrations at the Homosassa Springs group are typically below 0.7 mg/l. The concentrations vary among the individual springs of the group, possibly in response to mixing in the coastal transition zone and variations in nitrate in Floridan aquifer ground water. Research conducted by the water quality management plan indicates that the nitrate discharging from the springs is most likely derived from an inorganic source of nitrate - inorganic fertilizers applied to residential and golf course turf grass near the springs.
The Homosassa Main Spring was studied in 1992 by Karst Environmental Services (KES), a ground-water consulting firm. A portion of the study involved the mapping of the main-spring cave system by a team of divers. Their investigation revealed that the accessible portion of the system is not extensive. Most of the spring’s cavern system has developed in the Ocala Limestone. However, the contact between the Ocala Limestone and Avon Park Formation was observed to occur at a depth of 48 feet below sea level. The maximum depth reached by the divers in the cave was 70 feet. Although extremely narrow passages continued deeper into the system, they were judged to be beyond the safe reach of the divers. The divers also determined that most of the flow in the main spring emanates from three vents, each of which discharges water that is chemically distinct from the others. Subsequent samplings of the main spring were greatly improved by the installation of sampling tubes into the individual vents. Homosassa Springs is located within the Homosassa Springs State Wildlife Park. The main spring lies in a collapsed-cavern feature, and is comprised of three chemically distinct vents with vent #3 having the least salinity.
view from the boat dock
In order to log this cache, please submit answers to the following questions to the cache owner:
1. Homosassa Springs has brackish water. Explain why.
2. What springs comprise the Homosassa Springs group?
3. There is an underwater viewing platform at the main spring. Either take a photo or describe what you see here. Find out if the fish are fresh or saltwater species in this brackish water.
4. At the main spring's viewing platform, estimate the depth of the spring.
Send your answers BEFORE you log the cache or your log will be deleted without warning. If you have the time to log the cache, you have the time to comply with its requirements.
There is a charge for entering this park, currently $13.