Chassahowitzka Springs Group
Chassahowitzka Springs are the headwaters for the Chassahowitzka River, one of the most pristine and scenic rivers in Florida, accessible only by boat or canoe. Endangered West Indian manatees frequent the springs and river year-round but are especially common in winter.
This swampy area of the Springs Coast Basin along Florida’s west coast several thousand years ago was home to Native Americans who left behind evidence of their campsites in high, dry locations. A Weeden Island culture burial mound found at Indian Bend dates from AD 300 to 1300. The Seminole Indians who camped in the area during the Second Seminole War (from 1835 to 1842) named the area Chassahowitzka, meaning "pumpkin hanging place" (referring to a small, rare climbing pumpkin that may now be extinct).
In 1528 the Spanish conqueror and explorer Panfilo de Narvarez travelled north from Tampa Bay several miles inland from the coast, possibly along the eastern edge of the Chassahowitzka Swamp. Of the 300 men who accompanied him on his ill-fated expedition across Florida, only 4 survived.
Because of its ecological importance, the river has been designated as an Outstanding Florida Water and receives special protection to maintain its existing water quality.
Chassahowitzka Springs, which are located 5.8 miles (9.3 kilometers) southwest of Homosassa Springs on the Chassahowitzka River, comprise the river’s headwaters. As many as five springs flow into the upper part of the river, and many more springs are known to exist in the lower portion. Tides influence both the springs and river.
Chassahowitzka #1 Spring (Figure 1) issues from a small cavern in bedrock limestone. The spring pool is circular, and the depth over the two closely spaced spring vents is 8.3 feet. The water is clear and light blue. A small tannic stream flows into the northeast side of the spring pool, and a thin layer of algae covers most of the limestone bottom. The surrounding land is low-lying and heavily forested with hardwoods and palms.
The spring run from Chassahowitzka #1 Spring flows about 350 feet into the Chassahowitzka Main Spring pool from the east. There are several other spring vents along the spring run about halfway to the Main Spring. The Main Spring is located in the middle of the spring run at the head of a large circular pool that measures about 150 by 135 feet (Figure 2). The depth over the vent is 13.5 feet. The pool has a sand bottom, with no exposed limestone, and the water is clear and greenish. There is a boat ramp with facilities on the southwest side of the pool. Aquatic vegetation is common, including exotic aquatic vegetation and algae. A boil is visible at low tide. The spring is surrounded by lowland hardwood swamp forest with mixed hardwoods, cypress, and palm.
From its headwaters, the Chassahowitzka River flows approximately six miles west to the Gulf of Mexico through low-lying coastal hardwood hammocks and marshes. Generally, sand or sand/mud mixtures dominate the river bottom, with mud more prevalent near the shoreline. Small patches of exposed limestone occur sporadically along the river.
Submersed aquatic vegetation (SAV) is present throughout most of the river, although its density declines downstream as salinity increases. Filamentous macrolagae were reported to dominate the SAV community between 1998 and 2000, and were particularly abundant in the upper river. Common macrophytes observed during this period included native species such as tape grass, sago pondweed, and southern naiad, as well as two invasive exotic species, Eurasian watermilfoil and hydrilla.
Because of its nearly pristine natural condition, the Chassahowitzka River is one of the most scenic rivers in Florida. It is accessible only by boat or canoe. Both the Chassahowitzka Springs and River are used for activities such as fishing, swimming, snorkeling, and boating.
The Chassahowitzka Springs Group consists of at least 16 named Floridan aquifer system springs, all tidally influenced, which discharge directly into the Chassahowitzka River or its tributaries (Figure 3). Chassahowitzka Main Spring (Figure 2) has been sampled for major ions and nutrients as far back as 1946 by the U.S. Geological Survey (USGS), and the Southwest Florida Water Management District (SWFWMD) collected a large suite of water quality analytes—including nutrients and field and salinity indicators—at five of the major spring vents of this group from 2002 through 2012. Tables 1 through 5 summarize the results for selected analytes for each major spring.
Like many Florida springs, nitrate levels in all of the monitored Chassahowitzka River springs have been trending upward during the period of study (2002–12), with an approximate increase of 0.01 milligrams per liter (mg/L) nitrate + nitrite (measured as N) each year. During the same period, the predominant land use in the Chassahowitzka springshed has continued to transition from silviculture and limerock mining to urban and single-family residential, particularly around Brooksville, which lies within the Chassahowitzka Group springshed (Knochenmus et al. 2001).
Figure 4 shows the upward trend in nitrate concentrations for the five Chassahowitzka Spring Group springs studied. Looking back at the few nitrate + nitrite results collected from Chassahowitzka Main Spring prior to the 2000s confirms that this trend has been continuing for at least the past 66 years. In 1946, the nitrate concentration at Chassahowitzka Main Spring was measured at 0.068 mg/L, in 1962 it was 0.203 mg/L, and by the 1970s the mean value of the two samples on record was 0.209 mg/L (no nitrate + nitrite samples were reported at this site for the 1980s or 1990s). Although based on scant early data, the rise in nitrate + nitrite concentrations roughly corresponds to a possible increase of a little over 0.008 mg/L each year from 1946 to 2012.
Monthly rainfall measured at Tarpon Springs indicates a slight increase of 1.5 inches per year from 2002 to 2012 (Florida Climate Center 2012). Precipitation peaks roughly correlate with a lag in increasing quarterly nitrate + nitrite values measured at Chassahowitzka Main Spring and Chassahowitzka #1 Spring, which may indicate a nearby nutrient source.
Four of the sampled springs (Chassahowitzka #1 (Figure 1), Chassahowitzka Main (Figure 2), Crab (Figure 5) and Ruth (Figure 6) have very similar nitrate + nitrite values, hovering around 0.60 mg/L—well above the 0.35 mg/L numeric nutrient level established for Florida freshwater springs. The Florida Department of Environmental Protection 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 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 (DO) in the water. The very similar trends and concentrations for these four springs indicate the likelihood of a common ground water source (springshed) for the vents.
Baird #1 Spring (Figure 7) also shows an increasing nitrate + nitrite trend, although not increasing in concentration as fast as the other measured Chassahowitzka Group vents. Additionally, the nitrate + nitrite concentrations all fall below the 0.35 mg/L numeric nutrient level, indicating a potentially different upland ground water source for Baird #1 versus the other sampled Chassahowitzka springs.
Plotting the ratios of nitrogen isotopes versus oxygen isotopes 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 Chassahowitzka Main, Baird #3, and Baird #4 springs in January 2013. The results show that all values plot between the reduced, mineralized (organic) nitrogen and the organic nitrogen wastewater domains, indicating either a mixed organic nitrate signature or nitrogen derived from soil organic compounds. The relatively high DO value (mean Chassahowitzka Main value = 4.69 mg/L) implies that little denitrification has taken place.
The other macronutrient of concern in Florida surface waters, orthophosphate, is only present in low concentrations in all Chassahowitzka River springs, ranging from 0.013 to 0.018 mg/L (Tables 1 through 5). While elevated orthophosphate levels are problematic where surface runoff carries this nutrient into lakes and rivers from its sources, orthophosphate is generally not an issue 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 that remain within the host rock (Brown, 1981). 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.
Salinity indicators (sodium, chloride, sulfate, and specific conductance) show increasing values during the last decade (Figure 8), continuing an upward trend observable since 1946 at Chassahowitzka Main Spring, when sodium was 140 mg/L, chloride was 53 mg/L, sulfate was 35 mg/L, and specific conductance was 470 micromohs per centimeter. Comparing 1946 data with mean values measured from 2002 to 2012, sodium concentrations have increased threefold, chloride has increased fifteenfold, sulfate has increased more than threefold, and specific conductance has increased sevenfold. It is not known why chloride concentrations at Chassahowitzka Main Spring have increased fivefold over increases in sodium and sulfate concentrations. The salinity indicators were slowly rising until the mid-1990s, when the concentration increases became more pronounced.
There is a strong correlation at each spring between all of the salinity indicators. Chassahowitzka Main, Crab, and Ruth Springs have similar salinity indicator concentrations; Chassahowitzka #1 Spring has the lowest, and Baird #1 Spring has the highest.
The longer-term measured increases in salinity indicators reflect the potential upconing of deeper, more saline ground water due to increasing fresh ground water withdrawals from the Floridan aquifer system, decreasing precipitation patterns, steadily rising sea level, or a combination of these causes.
DO levels are important for fish and other biota, and are generally measured at levels below 5 mg/L in fresh ground water issuing from spring vents. The levels measured in the Chassahowitzka Springs Group are within this normal ground water range, with DO values in Baird #1 and Ruth Springs in the 1.5 to 2.6 mg/L range, and Chassahowitzka Main, Chassahowitzka #1, and Crab Spring ranging from 4.5 to 5.5 mg/L. Some fish species can tolerate lower DO levels and thrive in spring vent environments. DO levels generally rise rapidly in surface waters downstream from spring vents, due to plant respiration; however, the Chassahowitzka River is largely devoid of submersed aquatic vegetation (SAV) other than some species of filamentous algae.
Boron, not known to occur naturally in high concentrations in fresh Floridan aquifer system ground water, has recently been sampled as a possible wastewater tracer in wells and springs, due to its widespread use in laundry detergents. Historic (2002-2012) mean boron concentrations from Chassahowitzka Main and Chassahowitzka #1 springs were compared to historic chloride concentrations (from Tables 1-2), and boron/chloride ratios were calculated:
Chassahowitzka Main Spring: Boron/Chloride ratio = 0.000111
Chassahowitzka #1 Spring: Boron/Chloride ratio = 0.000166
All of these values are below the mean boron/chloride ratio measured in Atlantic Ocean seawater sampled along the U.S. coastline from south of Cape Cod to Bermuda, which is 0.000240 (Rakestraw et al, 1935). If one assumes that boron/chloride ratios in the Atlantic Ocean are similar to boron/chloride ratios of the small percentage of seawater entrained in Floridan aquifer system ground water, these numbers do not indicate a human boron wastewater component present in spring discharge from the Chassahowitzka Main and #1 spring vents. Boron results were not available for Crab, Ruth, or Baird #1 springs.
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. Only one sample of sucralose has been collected to date from Chassahowitzka Main Spring (on January 8, 2013); the measured concentration was 0.022 mg/L. This very low value lies between the laboratory detection limit and the laboratory practical quantitation limit. If confirmed by additional positive sampling results, this detection could indicate possible wastewater influences within the springshed.
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Endangered West Indian manatees frequent the springs and river year-round but are especially common in winter when they seek warmer water during cold spells. These huge, gentle animals, averaging 1,000 pounds, eat only aquatic plants. They cannot survive for extended periods in water colder than about 63°F.
The Chassahowitzka National Wildlife Refuge serves as a winter preserve for migratory and wintering waterbirds. About a fifth of this area is designated as habitat for the Florida black bear, the only native bear species found in Florida and the state’s largest land mammal.
The Southwest Florida Water Management District’s (SWFWMD) Chassahowitzka Riverine Swamp Sanctuary contains both uplands and wetlands. The trees and other plants found there include sand live oaks, fetterbushes, saw palmettos, longleaf pines, and turkey oaks. Wetland plants and trees include cypress, cabbage palms, sawgrass, sweetgum, and red maple. The sanctuary provides habitat for numerous animals such as Florida black bears, white-tailed deer, bald eagles, river otters, bobcats, ospreys, great blue herons, anhingas, cormorants, wood storks, and manatees.
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Historically, logging was the main land use in the area. In the early 1900s, virgin bald cypress was harvested in the Chassahowitzka Swamp. After the marketable cypress was removed, southern red cedar was logged to make pencils and cigar boxes. An enormous tram system was constructed for mules to haul timber from the swamp to a railroad in Homosassa. Many of the trams remain in operation and are now used by hunters, bikers, hikers, birders, and nature photographers.
From 1910 to 1922, Tidewater Cypress operated a lumber mill at Centralia, a boom town with a population of about 1,500, consisting of laborers and their families. These individuals came from diverse ethnic groups, including Greeks, Irish, and Germans. The town had a commissary, school, restaurant, theater, doctor, and dentist. The mill, one of the largest in the state, could produce as many as 100,000 board feet of lumber each day during peak periods. By 1922, however, there were no more logs to mill. Soon afterwards the railroad ceased operation, and Centralia became a ghost town. Today it lies in ruins. Only broken bricks, old train tracks, and the foundations of houses, the old train depot, and the lumber mill remain.
The community of Chassahowitzka is comprised of several hundred people; most live along a series of canals which discharge directly into the Chassahowitzka River just east of Chassahowitzka #1 Spring. Currently, there is a fish camp and boat ramp located on the south bank of Chassahowitzka Main Spring. Downstream development is mostly limited to a few isolated homes and fishing shacks located near the mouth of the river.
Although the area is not heavily populated, and water quality in the river and springs is generally good, recent studies have found increased nitrate levels and elevated bacteria levels in the canal system above the river's headwaters. Leaky septic tanks and excessive fertilizing of landscapes are two ways in which nitrates can enter the ground water supply and eventually appear in spring discharge.
Land acquisition has been the principal means of protecting the springshed and river. The U.S. Fish and Wildlife Service’s Chassahowitzka National Wildlife Refuge, which borders the Chassahowitzka River and includes the Chasshowitzka and Homosassa River Estuaries, was established in 1943 as a winter preserve for migratory waterbirds. Today, about 35,000 acres of this region, which includes the Chassahowitzka and Homosassa River estuaries, many islands, 12 miles of river, salt marshes, and coastal swamps, are protected and managed by several federal, state, and local governmental agencies. The area includes 7,500 acres designated as habitat for the Florida black bear.
Iin 1985, the state’s Conservation and Recreation Lands (CARL) Program purchased land from the Lykes Brothers and the Turner Corporation. In 1988, another 150 acres were added to compensate for the loss of red-cockaded woodpecker habitat in Marion County. In 1996, the first portion of the Weeki Wachee tract was purchased. The Seville and Annutteliga Hammock tracts east of Highway 19, purchased in 1998, provide an upland buffer for coastal lands and a geographic link to the Withlacoochee State Forest. In 2000, the Florida Fish and Wildlife Conservation Commission approved the purchase of an additional 720 acres.
In 1990, the SWFWMD began acquiring land for the Chassahowitzka Riverine Swamp Sanctuary. Today, the sanctuary comprises about 5,676 acres of land.
The Chassahowitzka Springs Restoration Project, begun in 2013 by SWFWMD, is designed to restore water quality, water clarity and bottom habitat (SWFWMD, 2013). The initial phase of this project involved the removal of accumulated sediment in the basin of Chassahowitzka Main Spring, and was completed in October, 2013. Suction pumps were used to remove excess sediment in the spring basin, and a number of archaeological artifacts, dating back from 12,000 years to present, were discovered in the process. Additional work on this project is ongoing.
When state land purchases are combined with federally and locally purchased land in the Chassahowitzka area, a total of 60,348 acres of land along the Chassahowitzka River have been preserved.
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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/)
- Citrus County (https://www.bocc.citrus.fl.us/)
- Hernando County (http://www.hernandocounty.us/)
- 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)
- Save the Manatee Club (http://www.savethemanatee.org/)
- Hernando County Groundwater Guardian (http://www.hernandocounty.us/utils/groundwater/)
- Hernando Environmental Land Protectors (http://flhelp.nccsfl.com/)
Parks and Conservation Areas
- Chassahowitzka National Wildlife Refuge (http://www.fws.gov/chassahowitzka/)
- Chassahowitzka Wildlife Management Area (http://myfwc.com/viewing/recreation/wmas/lead/chassahowitzka/)
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