KISSIMMEE RIVER & FISHEATING CREEK BASINS. Hydrogeological Setting

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Bertram Elmer Arnold
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1 KISSIMMEE RIVER & FISHEATING CREEK BASINS Hydrogeological Setting The three principal Florida aquifer systems - surficial, intermediate and Floridan - all exist beneath the entire Kissimmee River Fisheating Creek Basin area. These aquifer systems are defined and separated based primarily on variations in lithostratigraphy. The surficial aquifer system comprises the many uppermost unconfined aquifers within these two basins. The surficial is recharged throughout the two-basin area primarily from direct downward percolation of rainfall. The surficial aquifer system is used sparingly for domestic and agricultural supply, primarily in the southern half of the two-basin area. The sediments comprising the surficial aquifer system are from several lithostratigraphic units. In the Kissimmee River Basin area, the surficial occurs in the undifferentiated Pliocene Pleistocene sediments, Cypresshead Formation and shell beds of the Caloosahatachee and Fort Thompson Formations. In the Fisheating Creek Basin area, sediments of the Tamiami, Caloosahatchee/Fort Thompson Formations and undifferentiated sediments comprise the aquifer system (Scott, T.M., in Maddox et al, 1992). The surficial varies in thickness from over 400 feet along the western margin of the Kissimmee River Basin adjacent to and along the Lake Wales Ridge, to as little as 100 feet or less in the southern portion of the Fisheating Creek Basin. The base of the surficial aquifer system occurs at the first impermeable sediments of the Hawthorn Group. Occasionally, upper Hawthorn Group sediments may form the basal portion of the surficial aquifer system. The lithostratigraphic units forming the surficial aquifer system consist of a complex array of facies. The sediments range from quartz sands to limestones with varying admixtures of shell and clay. As a result of this variability, water quality within the surficial aquifer system can change dramatically from place to place. The intermediate confining unit/ aquifer system occurs throughout the Kissimmee Fisheating Creek basins. The intermediate aquifer is primarily recharged from downward movement of surficial aquifer system waters. Interbedded siliciclastic and carbonate sediments of the Hawthorn Group host the intermediate confining unit and aquifer system. In portions of the Kissimmee River Basin, Tamiami-equivalent sediments may form the top of the intermediate confining unit (Scott, T.M., in Maddox et al, 1992). The top of the Hawthorn Group (roughly corresponding to the top of the Intermediate aquifer system / confining unit) ranges from about 50 feet above mean sea level in the northern reaches of the Kissimmee River Basin to about 100 feet below mean sea level along the southeastern margin of the Basin. Thickness of the intermediate aquifer system / confining unit ranges from approximately 500 feet in the northern Kissimmee River Basin area to more than 600 feet in the southernmost portion of the Fisheating Creek Basin (Scott et al, 1991), although this zone is perforated beneath and in the vicinity of sinkhole lakes. Permeable transmissive siliciclastic and carbonate zones within the intermediate confining unit increase in thickness and extent in the southwestern portion of the two-basin area. The base of the intermediate aquifer system / confining unit generally corresponds with the top of the Oligocene Suwannee or Ocala Limestones. The importance of the intermediate aquifer system as a primary source of potable water increases westward within the Fisheating Creek Basin areas of southern Highlands and western Glades counties. Within the Kissimmee River Basin, the intermediate is not very productive, and is seldom used as a water supply source.

2 The Floridan aquifer system resides within the thick, highly productive sequence of Tertiary carbonate sediments and siliciclastic-rich carbonates which mostly lie beneath the Hawthorn Group. It can be subdivided into an upper Floridan and lower Floridan aquifer beneath most of the two-basin area. Siliciclastic-bearing carbonates and a few siliciclastic beds from the basal Hawthorn Group may form the upper beds of the Floridan aquifer system in some portions of the two basins. In general, the Suwannee Limestone forms the upper unit of the aquifer system with the Ocala Limestone and the Avon Park, Oldsmar and upper Cedar Keys Formations comprising the balance of the system. The base of the Floridan aquifer system, corresponding to the top of the sub- Floridan confining unit, occurs within the upper portion of the Cedar Keys Formation (Miller, 1986). The altitude of the top of the Floridan aquifer system ranges from sea level in the northernmost part of the Kissimmee River Basin to over 650 feet below mean sea level in the southeastern portion of the Fisheating Creek Basin adjacent to Lake Okeechobee (Scott et al, 1991). The thickness of the Floridan ranges from less than 2300 feet in the northern fringes of the Kissimmee River Basin near Orlando to more than 3400 feet under the southwestern portion of the Fisheating Creek Basin (Miller, 1986). Primary recharge to the Floridan aquifer system occurs along the northern and western boundaries of the Kissimmee River valley. The Floridan aquifer system ground water basin does not correspond to the Kissimmee River Basin, particularly in the far northern reaches where Floridan waters recharge aquifer areas to the north. Within all but the southernmost portion of the Kissimmee River Basin, Floridan aquifer system wells are the primary suppliers of potable water. South of a line running southwest to northeast approximately following the Highlands Glades County border, and extending northeast to just north of the town of Okeechobee, the Floridan is too saline to be used as a potable water supply. Basin Ground Water Issues Ground-Water Contamination Heavy urban development occurs primarily at the northern edge of the Kissimmee River Basin, which comprises the fast-growing southern half of the metropolitan Orlando area. Within this area are a number of limited-extent ground-water contamination sites, mostly associated with small-scale industries and leaking underground fuel storage tanks. However, also within this area are a number of drainage wells and galleries which divert stormwater into the Upper Floridan aquifer. This is done to compensate for aquifer withdrawals in the urban area, to increase recharge, control lake levels and to suppress upward migration of sub-floridan mineralized waters. The City of Orlando s water supply wells tap the same aquifer zone in the same geographic areas, without significant degradation of water quality (Schiner and German, 1983). Cattle dip vats are ubiquitous to most of Florida, and hundreds of these have been identified in the Kissimmee River Fisheating Creek basins. Approximately 3400 cattledipping vats were constructed throughout Florida from 1906 through These vats were used to eradicate ticks from cattle and other livestock. The vats were constructed of concrete and were typically 30 feet long, 3 feet wide and 7 feet deep. The vats were generally filled with an arsenic solution that killed the ticks. It is now known that the solutions used in these cattle-dipping vats are harmful to humans and areas with the vats may have contaminated ground water in their vicinity. Other possible contaminants

3 are BHC, DT, DDE and toxaphene (FDOH, 2003). Most of the potential aquifer contamination resulting from cattle-dipping vats is extremely localized, and these facilities are not considered to be hazardous on a regional scale. Karst Features The development of karst features within the sediments of the Floridan aquifer system is primarily expressed at the surface as large sinkhole lakes. These mainly occur within the northern portion of the Kissimmee River Basin, and to some degree along the western boundary of the Basin on the eastern flanks of the Lake Wales Ridge. Surface water ground-water exchange can occur through the bottom sediments of these lakes, depending on the thickness, composition and resultant transmissivity of these lake bottom/sinkhole collapse sediments. As a result, contaminated lake waters can in some instances move downward into the Upper Floridan aquifer, and vice versa. Superfund Sites According to the U.S. Environmental Protection Agency (U.S. EPA, 2003), there are no National Priority List (Superfund) contaminated sites within the Kissimmee River Fisheating Creek basins. Delineated Areas Concentrations of ethylene dibromide (EDB) in exceedance of the Primary Drinking Water Standard of 0.02 µg/l (Baker, 1994) have been detected in numerous wells along the Lake Wales Ridge at the western edge of the Kissimmee River Basin. EDB was used primarily to control nematodes in citrus groves. It is no longer used, but relict high concentrations persist in portions of aquifers along the Lake Wales Ridge area of Polk and Highlands counties. Most of the areas where these wells occur have been designated as ground-water delineated areas for EDB. Activities such as new well construction are forbidden or tightly regulated within these areas. Concentrations of dibromochloropropane (DBCP) in exceedance of the Primary Drinking Water Standard of 0.2 µg/l (Baker, 1994) have been detected in several wells within the same general areas as EDB. Water Use Caution Areas Water Use Caution Areas (WUCAs), designated by Florida s water management districts, are regions where water resources are or will become critical in the next 20 years (SWFWMD, 2003). In these areas, coordinated regional efforts include incentives and projects that investigate, correct and prevent harm to the water resource; regulatory initiatives; development of alternative sources; and widespread education efforts. WUCAs are usually designated in areas of salt water intrusion into aquifers, or where ground-water pumping has negatively affected lakes, wetlands and other natural ecosystems. Southwest Florida Water Management District s (SWFWMD) Southern Water Use Caution Area includes portions of the Kissimmee River - Fisheating Creek basins which lie within the SWFWMD boundaries in Polk and Highlands counties. This particular WUCA was developed to address declining lake levels on the Lake Wales Ridge area of Polk and Highl;ands counties, which is a major recharge area for the Floridan aquifer system. Salt Water Intrusion Due to their inland locations, the Kissimmee River Fisheating Creek basins are not directly threatened by coastal intrusion of saline waters from oceanic sources.

4 Overpumping of the Floridan aquifer system within these basins could potentially cause upwelling of sub-floridan brines; this has not yet happened in this region. Aquifer Storage and Recovery As a part of the Comprehensive Everglades Restoration Plan (CERP), up to 200 aquifer storage and recovery (ASR) wells with a capacity of up to one billion gallons per day will be installed in the Lake Okeechobee region to capture and store excess surface water runoff. A number of these wells will be installed in the Kissimmee River Fisheating Creek basins. The purpose of this project is to 1) provide additional regional storage while reducing both evaporation losses and the amount of land needed for construction and operation of traditional above-ground reservoirs; 2) increase the storage capacity of Lake Okeechobee to better meet regional water supply demands; 3) manage a portion of regulatory releases from the Lake to improve Everglades hydrologic flow patterns and to meet supplemental water supply demands of the Lower East Coast; 4) reduce harmful regulatory discharges to the St. Lucie and Caloosahatchee estuaries and 5) maintain and enhance the existing level of flood protection (CERP 2003). After treatment, water from Lake Okeechobee will be injected into and stored in the Upper Floridan aquifer during high water periods, to be pumped back out, aerated, and returned to the Lake during the dry season. The returned water would purportedly have no adverse water quality effects on Lake Okeechobee surface waters, and may even promote some level of nutrient-load reduction, depending on the level of pre- and post-treatment of ASR waters. One of the CERP Pilot ASR Projects has been permitted and built in the Kissimmee River Basin, near the Kissimmee River outfall into Lake Okeechobee. It consists of one ASR well, with a five million gallon per day permitted capacity. How this, and other ASR projects affect aquifer water quality will likely depend on the volume, underground residence time and level of pre-treatment of injected waters.

5 REFERENCES CITED Baker, Bryan, 1994, Ground Water Guidance Concentrations: Florida Department of Environmental Protection, 53 p. Comprehensive Everglades Restoration Plan (CERP), 2003, Website information on aquifer storage and recovery (ASR) projects: Florida Department of Health (FDOH), 2003, Bureau of Water Programs website: Maddox, G.L., J.M. Lloyd, T.M. Scott, S.B. Upchurch and R.E. Copeland, 1992, Florida s Ground Water Quality Monitoring Program Background Hydrogeochemistry: Florida Geological Survey Special Publication 34, 364 p. Miller, J. A., 1986, Hydrogeologic framework of the Floridan aquifer system in Florida and parts of Georgia, Alabama and South Carolina: United States Geological Survey Professional Paper B, 91 p. plus maps. Schiner, G. H. and E. R. German, 1983, Effects of Recharge from Drainage Wells on Quality of Water in the Floridan Aquifer in the Orlando Area, Central Florida: U.S. Geological Survey Water Resource Investigations Report , Tallahassee, Florida. Scott, T.M., J.M. Lloyd, G.L. Maddox and R.E. Copeland, 1991, Florida s Ground Water Quality Monitoring Program Hydrogeological Framework: Florida Geological Survey Special Publication 32, 97 p. Scott, T.M., 1992, Hydrostratigraphy, in Maddox, G.L., J.M. Lloyd, T.M. Scott, S.B. Upchurch and R.E. Copeland, 1992, Florida s Ground Water Quality Monitoring Program Background Hydrogeochemistry: Florida Geological Survey Special Publication 34, p Southwest Florida Water Management District (SWFWMD), 2001, Southern Water Use Caution Area Issue Paper; from website: U.S. Environmental Protection Agency, November 17, 2003, Superfund website:

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