The Aripeka Springs Group is located along Florida’s west coast within the Springs Coast Basin. This spring group is part of the Hammock Creek system, a coastal system formed by a number of lesser-magnitude springs and swamp discharge. The springs are clustered in a one-square-mile area in southwestern Hernando County, near the town of Aripeka. The water discharging from the springs has probably not been in the aquifer for more than a few decades at most.
Aripeka Spring #1
Aripeka Spring #1 (Figure 2) is located on the bottom of upper Hammock Creek, about half a mile northeast
of the town of Aripeka. The spring occupies a 15-foot-diameter depression on the bottom of the creek. The depth over the spring vent is 6.2 feet at high tide. A small boil is present on the spring surface over the vent. The spring water is murky and greenish, and the spring bottom is soft sand and mud. The discharge is estimated at less than five cubic feet per second (cfs).
Hammock Creek in the vicinity of Aripeka Spring #1 is a brackish marsh habitat. Beyond the spring, northward up the run, several small tidal creeks branch off. A palm-hardwood hammock is located at the
head of Hammock Creek 250 feet north of the spring.
Aripeka Spring # 2
Aripeka Spring #2 (Figure 3) is located 300 feet upstream from the mouth of the southernmost tributary of upper Hammock Creek, just northeast of the town of Aripeka. The spring occupies a small circular cove along the north side of Hammock Creek. The spring is 6 feet deep at high tide, and discharges slightly murky water. A small boil is present over the vent. The spring bottom is soft mud and sand. Aripeka Spring #2 is next to a 5-foot-tall fern thicket surrounding the northern half of the spring cove. The fern thicket is an island of larger vegetation within a wide-open expanse of brackish marsh. The discharge is estimated at less than five cfs.
As in other areas of the Springs Coast Basin, the Aripeka Springs Group comprises Floridan aquifer system springs. These either discharge directly into Hammock Creek or into the lesser creeks flowing into Hammock Creek. Hammock Creek is approximately one mile long and is joined by several lesser tidal creeks before reaching the Gulf of Mexico. The creek’s water is brackish nearly to the headsprings.
Boat Spring (Figure 4) is located at the head of the middle tributary to Hammock Creek, half a mile
northeast of the north of the town of Aripeka. The spring occupies an elongated spring pool near the head of a tidal tributary creek to Hammock Creek. The pool is 40 feet long by 20 feet wide and has five vents. The spring measures 3.7 feet deep over the vent at high tide, and the water is murky and greenish. Limestone is exposed along the pool edges and bottom, along with dark mud. No spring boil was visible during a 2003 visit, most likely because of high tide conditions.
Channel modification or canal digging appears to have altered the tidal creek approximately 200 feet downstream from the spring. Boat Spring discharges through a 0.2-mile-long tidal creek that feeds into the east side of Hammock Creek, approximately 700 feet downstream from Aripeka Spring # 1. Boat Spring is surrounded by privately owned, dense palm-hardwood-cedar hammock lands. In 1998–99, the discharge averaged 1.25 cfs.
Bob Hill Spring
Bob Hill Spring (Figure 5) is situated in a hammock about 600 feet north of the Pasco-Hernando County line. The spring is 15 feet deep, and the discharge flows west to the Gulf via Bayou Creek and Bayou Lake.
Once a 200-acre homestead owned by the Hill family, the property was subdivided in 1953, becoming part of the Gulf Coast Highway Estates subdivision. In the 1970s, it was turned into a privately owned recreational and camping facility. The spring was converted to a 100- by 200-foot oval swimming pool with concrete walls and a paved walkway surrounding the entire spring. The spring has been renamed Holiday Springs, which is the name of the RV Park, and a major road now divides the land once owned by the Hills. While the spring boil was once prominent and continuous, in 1972 the discharge was significantly reduced after a nearby area was excavated for a lake.
Gator Spring (Figure 6) is located 0.8 miles west of Aripeka near the head of the south fork of Hammock Creek. It is on private property and is inaccessible to the public. The elongated spring pool measures 114 feet by 195 feet, with a sand bottom, and ranges from 3 feet to 7 feet deep. The pool has been altered to form a swimming pond; however, there is no evidence of recent use. No boil was observed over the spring vent in the west side of the pool during a 2003 visit. The water is clear with a greenish hue.
Algae are both suspended in the water and attached to substrates. There is aquatic and emergent vegetation in and around the spring pool. A small culvert on the northwest side of the pool drains the meager flow from the spring and channels the water through an earthen dam into the spring run. Some limestone boulders are present near the culvert and the vent.
Gator Spring Run is a small, narrow, sand-bottomed stream that flows southwest for approximately 350 feet and enters upper Magnolia Spring Run, just below Magnolia Spring. There is a private residence approximately 350 feet west of Gator Spring. The formerly cleared land surrounding the spring is now overgrown with dense brush.
Magnolia Spring (Figure 7) is located 0.7 miles west of Aripeka at the head of the south fork of Hammock Creek. The spring is on private property and is inaccessible to the public. It sits in an oval depression measuring 45 feet by 54 feet. The spring pool is shallow, averaging 4 feet deep. The water is clear and light blue, with little aquatic vegetation covering a sand bottom. There is a private residence approximately 300 feet to the north. At least a dozen small sand boils are visible on the spring bottom.
Gator Spring Run enters Magnolia Springs Run from the northeast approximately 75 feet downstream from the headspring. Magnolia Springs Run is clear and sand-bottomed. It averages 20 feet wide and 3 feet deep, with frequent constrictions and shallow areas. There is a small private boat/canoe shack on the northwest side of the spring pool. The spring and its run are situated in a heavily wooded, lowland swamp. Magnolia and Gator Springs form the headwaters of the south fork of Hammock Creek.
The Aripeka Springs Group consists of at least nine Floridan aquifer system springs, most tidally-influenced, which discharge directly or indirectly into Hammock Creek or nearby tributaries which flow directly into the Gulf of Mexico (Figure 1). All are third-magnitude or smaller dischargers; some only appear to flow intermittently, only on slack tides or during wetter periods of the year.
The springshed for the Aripeka Group springs extends from Aripeka southeastward from the Hernando – Pasco County line into central Pasco County along the Brooksville Ridge (Knochenmus et al, 2001). Land use within the springshed consists of a nearly equal mix of low to medium density residential and upland forest,
with some land dedicated to pasture or row crops (Jones et al, 1997). Three small springs located 2.4 – 9.5 km (1.5 – 6 miles) southwest of the Town of Aripeka (Double Keyhole, Horseshoe (Figure 8) and Isabella springs) all discharge into coastal wetlands, and are included in the Aripeka Springs Group. Horseshoe and Isabella springs have no water quality data available for the 2002-2012 period of study. The spring pool for Double Keyhole can be clearly seen in aerial photos and online services such as Google Earth. It is located just west of an area of extensive dragline limerock mining.
Some Aripeka Group springs been sampled for major ions and nutrients as far back as the early 1960’s by the U.S. Geological Survey (USGS), and SWFWMD has collected a large suite of water quality analytes, including nutrients and field indicators, at four of the major spring vents of this Group during the period from 2002 through 2012. Tables 1-7 summarize the results for selected analytes for each major spring.
Nitrate levels in most of the monitored Aripeka Group spring vents (Aripeka Springs #1 and #2, Boat, Bob Hill, Gator and Magnolia springs) exceed the 0.35 mg/L numeric nutrient criteria used to determine potential nutrient impairment (Figure 9).
The Department has determined that nitrate concentrations above 0.35 mg/L indicate potential waterbody impairment; this number is based on recent research conducted in Florida spring waters, which found that some of the most prevalent species of algae proliferate when nitrate levels exceed that concentration. Excessive amounts of algae can smother essential habitat for fish and other wildlife, displace native plants, and deplete the amount of dissolved oxygen in the water. Bob Hill Spring, located farther inland than any of the other Aripeka Group springs, has the highest measured nitrate + nitrite concentrations. Of the springs with nutrient data available, Double Keyhole Spring is the only one which has nitrate + nitrite values below the numeric nutrient criteria level; however, the balance of data from these springs has only been collected since 2010. Nitrate trends are either flat or increasing; lack of past data from these springs hampers more thorough study.
Plotting the ratios of nitrogen isotopes (15NNO3/14NNO3) versus oxygen isotopes (18ONO3/16ONO3) in nitrate measured from ground water can reveal likely nitrate sources: inorganic (chemical fertilizers) or organic (wastewater, septic discharge, animal waste) (Roadcap et al, 2002). Nitrogen and oxygen isotopes were analyzed from single samples collected from Aripeka Springs #1 and #2 and Magnolia Spring in January, 2013. The results show that all values plot within the domain indicative of an organic nitrate source: soil organic matter, septic/manure or a combination of these sources. The data also indicate little or no denitrification, possibly indicating nearby nutrient sources or recent groundwater recharge. Elevated salinities measured in Aripeka Springs #1 and #2 might affect these results.
The other macronutrient of concern in Florida surface waters, orthophosphate, is only present in low concentrations in Aripeka Group springs, with mean values ranging from 0.006 – 0.017 mg/L (Tables 3-7) during the period of study. While elevated orthophosphate levels are problematic in many of Florida’s lakes and rivers where surface runoff carries this nutrient into these waterbodies from its sources, measured orthophosphate levels are low in springs. This is due to its attenuation within limestone aquifers where, given enough time, orthophosphate reacts with calcium carbonate to produce low-solubility calcium phosphate minerals which remain within the host rock (Brown, 1981). Given enough time, this effectively removes orthophosphate from the waters within the aquifer, and is the probable geochemical mechanism by which “hard rock” phosphate deposits have developed in the state.
The submerged aquatic vegetation currently present in Aripeka Group springs discharging into brackish waters is difficult to observe due to murky water (Aripeka #1, Boat, and Horseshoe springs). In springs with clear water discharge (Aripeka #2, Gator and Magnolia springs), green filamentous algae and green algae coating limerock surfaces predominate.
Salinity indicator analytes (sodium, chloride, sulfate and specific conductance) delineate two populations of spring water types within the Aripeka Springs Group: fresh (Bob Hill, Magnolia and Gator springs) and moderate to highly saline (Aripeka #1 and #2 and Double Keyhole springs). Sodium, chloride and sulfate analyses are lacking for most of these springs; thus, specific conductance values were primarily used to indicate salinity levels. Specific conductance values show a steady increase over the study period for springs with enough data to detect trends. These increasing trends are evident in specific conductance values plotted for Boat Spring (Figure 10) and Bob Hill Spring (Figure 11). Looking at specific conductance values for Boat Spring from 1964 – 2012 shows a steadily-increasing trend, with mean 1964 values around 300 µmhos/cm. These values increase in a roughly linear fashion over time, with mean specific conductance values of 1672 µmhos/cm for the study period from 2002 – 2012. The longer-term measured increases in salinity indicators reflect potential upconing of deeper, more saline ground water or landward movement of the fresh water / salt water interface possibly due to decreasing precipitation, increasing fresh ground water withdrawals from the Floridan aquifer system, steadily rising sea level or a combination of these causes.
Dissolved oxygen (DO) levels are important for fish and other aquatic biota, and are generally measured at levels below 5 mg/L in fresh ground water issuing from spring vents. The levels measured in the Aripeka Springs Group are within this normal ground water range, with mean DO values in the 1.20 – 4.69 mg/L range (Tables 1-7). Some fish species can tolerate lower dissolved oxygen levels, and thrive in spring vent environments. Dissolved oxygen levels generally rise rapidly in surface waters downstream from spring vents, due to plant respiration.
Boron has recently been sampled as a possible wastewater tracer in wells and springs, due to its widespread use in laundry detergents. Single boron values were available for only Magnolia and Gator springs for the study period – not yet enough data to draw conclusions from.
Sucralose is used as an artificial sweetener. Because it passes through water treatment systems largely intact, it has recently been used as a potential human wastewater tracer. No sucralose samples were collected during the period of study.
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The Springs Coast, including the Aripeka area, contains one of the largest and most spectacular mixtures of salt marshes and brackish marshes in Florida. The low-energy coastline gives rise to an intricate mosaic of marshes and coastal hammocks, where small changes in elevation, tidal inundation, soil characteristics, and freshwater flow control the various zones of vegetation. The brackish vegetation is perennial but dies back in the fall, providing organic detritus that feeds species at the base of the food chain. Both salt marshes and brackish marshes are highly productive. The large quantities of nutrients and organic particulates from tides and river flows support abundant phytoplankton, algae, and vascular plants.
The denser marsh vegetation in shallower waters provides a nursery area and a habitat that supports an important part of the food chain. Some animals are specifically adapted to this habitat. Species that use marshes include the hispid cotton rat, red-winged blackbird, sandhill crane, American bittern, king rail, Florida green water snake, roundtailed muskrat, peninsula newt, several kinds of frogs, and a number of small fish species. Insects, crayfish, snails, and other invertebrates are also abundant, providing a good food source for wading birds, raptors, and other predators. Marshes that go dry periodically are particularly important feeding habitat for wood storks. Plant species include maidencane, pickerelweed, bladderwort, and bluestem. Cordgrass and swamp hibiscus are found in mildly brackish areas near the coast. Cattail marsh grows in areas of high fertility.
Saltmarsh species are frequently exposed to harsh and variable conditions. Conditions in the marsh change with tidal ebbs and flows, resulting in salinity, temperature, oxygen, and pH fluctuations. Conditions can also vary from one area to another. Some animal species live permanently in the marshes; others use them only during certain seasons or stages in their life cycles. Fish are seasonally very abundant and diverse.
Over 60 species of birds, including wading birds and shorebirds, use the area’s salt marshes for food, nesting areas, and refuges.
The tricolored heron is the most abundant species. The marshes in this area are also an important wintering area for the largest concentration of redhead ducks in the southeastern United States and also provide feeding sites for bald eagles. Reptiles and mammals found in the basin’s salt marshes include the Gulf salt marsh snake, diamondback terrapin, American alligator, marsh rabbit, marsh rice rat, hispid cotton rat, and Duke’s saltmarsh vole.
The significance of the estuaries along the Gulf coast far exceeds their size. These areas provide essential habitat for numerous fish and wildlife species, including nursery and juvenile habitats for many recreational and commercial fish species. The economic value of commercial seafood harvests on Florida's west coast consists of at least 95% estuary-dependent species. Collectively, in 1999 the counties of the Springs Coast Basin generated almost 20,000 fishing trips and landed over 5.1 million pounds of seafood. Recreationally and commercially important species in the estuaries of the Springs Coast Basin include striped mullet, red drum, spotted sea trout, Gulf menhaden, Atlantic croaker, sea catfish, gafftopsail catfish, bay anchovy, and striped anchovy. Two species of sea turtles are occasionally found here: the Atlantic loggerhead and Atlantic leatherback.
Soft-bottom areas such as mud and sand contain many different species, most of which are buried in the bottom sediments, or live and feed on the bottom. Recreationally and commercially important species found in these areas include southern flounder, northern quahog, sunray venus, and blue crab.
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The population of Hernando County in 1990 was about 100,000; by 2020 it is projected to reach almost 200,000. There is also a large influx of seasonal residents during the winter months. Nonetheless, Hernando County and neighboring coastal counties—which are mostly covered by coastal swamps, dense woodlands, lakes, and pastures—have retained their rural character. A significant portion of Hernando County’s economy is still based on industry (including mining), cattle, and agriculture.
However, several factors, including residential growth, the decreasing profitability of farming, and freezes affecting the citrus industry, have dramatically altered land uses in the area. Residential and commercial development has rapidly expanded along the narrow U.S. Highway 19 corridor that runs between the coastal swamps and the upland forest of the Brooksville Ridge. Today, local economies predominantly comprise retail trade, services, government, and construction. Fertilizers used on golf courses, residential turf, and landscapes are the dominant sources of increased nitrate concentrations in the Hammock Creek system. Septic tanks are also a significant source.
While the Aripeka Springs Group discharges less fresh water than neighboring first-magnitude spring systems, which have flows of more than 100 million gallons per day, these springs remain an important part of the marine/estuarine ecosystem along the Gulf Coast. Their discharge is rapidly delivered to estuarine and marine areas via coastal creeks. As nitrate concentrations continue to rise, it is likely that estuarine algal blooms will increase in frequency and duration, and the vegetative composition of the estuarine aquatic systems will be altered.
The Southwest Florida Water Management District (SWFWMD) Springs Coast Comprehensive Watershed Management team has initiated the Nitrate Remediation Workgroup to address impacts to the region’s springs and drinking water sources caused by increasing nitrate levels in ground water and surface water. To achieve this goal, the workgroup engages in public education and the exchange and dissemination of information on research, education, and regulatory remediation and prevention measures with other organizations addressing similar problems throughout the state. The workgroup is composed of citizens, industry, and government representatives, including the SWFWMD.
The Florida Department of Environmental Protection (FDEP, or Department) has determined that the Aripeka Springs Group is impaired for nutrients—meaning that increased nutrient concentrations are causing an imbalance in natural populations of aquatic plants and animals. The Department is currently in the process of developing a Total Maximum Daily Load (TMDL) for the spring, which will ultimately result in the reduction in nutrients. A TMDL is the maximum amount of a given pollutant that a waterbody can assimilate and still meet water quality standards. The restoration of ecological health in the spring and spring run depends heavily on the active participation of stakeholders in the springshed, who are required to develop projects to reduce nutrient concentrations.
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Florida Department of Environmental Protection
Water Quality Evaluation & TMDL Section
Rick Hicks, PG Administrator
Contact for: General springs information
Springs Coast Water Quality Restoration Program
Terry Hansen, Basin Coordinator
Phone: (850) 245-8561
Contact for: Information on basin management action plan (BMAP)
Local Government and Water Resource Agencies
- Southwest Florida Water Management District (http://www.swfwmd.state.fl.us/)
- Hernando County (http://www.hernandocounty.us/)
- Pasco County (http://www.pascocountyfl.net/)
- Florida Geological Survey
- U.S. Geological Survey – Florida Water Science Center (http://fl.water.usgs.gov/infodata/)
- Florida's water: ours to protect
Citizen Stakeholder and Watershed Organizations
- Gulf Coast Conservancy (http://www.gulfcoastconservancy.org/index.htm)
- Hernando County Groundwater Guardian (http://www.hernandocounty.us/utils/groundwater/)
- Hernando Environmental Land Protectors (http://flhelp.nccsfl.com/)
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