Geology topics

Research about Lee County, Florida

Source-linked reports with geographic coverage including Lee County, Florida.

9 recordsLinked to original sources

USGS1999

Reconnaissance of chemical and physical characteristics of selected bottom sediments of the Caloosahatchee River and estuary, tributaries, and contiguous bays, Lee County, Florida, July 20-30, 1998

This report summarizes a reconnaissance study, conducted July 20-30, 1998, of chemical and physical characteristics of recently deposited bottom sediments in the Caloosahatchee River and Estuary. Recently deposited sediments were identified using an isotopic chronometer, Beryllium-7 (7Be), a short-lived radioisotope. Fifty-nine sites were sampled in an area that encompasses the Caloosahatchee River (River) about three miles upstream from the Franklin Lock (S-79), the entire tidally affected length of the river (estuary), and the contiguous water bodies of Matlacha Pass, San Carlos Bay, Estero Bay, Tarpon Bay, and Pine Island Sound in Lee County, Florida. Bottom sediments were sampled for 7Be at 59 sites. From the results of the 7Be analysis, 30 sites were selected for physical and chemical analysis. Sediments were analyzed for particle size, total organic carbon (TOC), trace elements, and toxic organic compounds, using semiquantitative methods for trace elements and organic compounds. The semiquantitative scans of trace elements indicated that cadmium, copper, lead, and zinc concentrations, when normalized to aluminum, were above the natural background range at 24 of 30 sites. Particle size and TOC were used to characterize sediment deposition patterns and organic content. Pesticides, polychlorinated biphenyls (PCBs), and carcinogenic polycyclic aromatic hydrocarbons (CaPAHs) were determined at 30 sites using immunoassay analysis. The semiquantitative immunoassay analyses of toxic organic compounds indicated that all of the samples contained DDT, cyclodienes as chlordane (pesticides), and CaPAHs. PCBs were not detected. Based on analyses of the 30 sites, sediments at 10 of these sites were analyzed for selected trace elements and toxic organic compounds, including pesticides, PCBs, and PAHs, using quantitative laboratory procedures. No arsenic or cadmium was detected. Zinc was detected at two sites with concentrations greater than the lower limit of the range of sediment contaminant concentrations that are usually or always associated with adverse effects (Florida Department of Environmental Protection's Sediment Quality Assessment Guidelines). Organochlorine pesticides were detected at four sites at concentrations below the reporting limits; there were no organophosphorus pesticides or PCBs detected. PAHs were detected at eight sites; however, only four sites had concentrations above the reporting limit.

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USGS1986

Surficial aquifer system in eastern Lee County, Florida

The surficial aquifer system in eastern Lee County consists of an upper water bearing unit, which is generally unconfined, and a lower water bearing unit, which is confined and is the major source tapped by most wells. The top of the lower unit, which is of primary interest in this report, ranges in depth from 40 to 60 ft below land surface in the east-central part of the county to more than 120 ft in the southern part. In the extreme southern part of the county, a middle water bearing unit also contains water under artesian pressure. Recharge to the lower unit occurs primarily by leakage from the overlying saturated section through the confining beds. Water levels in the lower unit fluctuate similarly to those in the upper (unconfined) unit. Groundwater in the lower unit moves from areas of highest water level in the south part of Lehigh acres, northward toward the Caloosahatchee River, and toward the coast. The lower unit contains freshwater throughout much of its extent and is the source of public water supply at Lehigh Acres and Green Meadows where an average of about 3 mil gal/day was withdrawn in 1980. In several areas, the concentrations of chlorides and dissolved solids exceed drinking water standards. Yields of wells that tap the lower unit range from 10 to 1,100 gal/min. Transmissivities ranging from about 17,700 to 7,750 sq ft/day were determined for different areas of the unit. Storage coefficients range from 0.0001 to 0.0003. (Author 's abstract)

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USGS1986

Tests for injecting, storing, and recovering freshwater in a saline artesian aquifer, Lee County, Florida

An investigation was made of the suitability of a saline, artesian limestone aquifer for the injection, storage, and recovery of freshwater from the Caloosahatchee River. The tests were conducted on a well tapping a leaky artesian system that has a transmissivity of 800 square feet per day, a storage of 1 x 10-4, and a leakance of 0.01 per day. The specific capacity of the injection well was increased through acidizing and was decreased as a result of well clogging during injection. Three injection tests were made wherein the amounts of freshwater injected, the storage duration, and the quality of water injected varied. Analysis of the test data showed that freshwater recoverability ranged from 9.7 to 38.7 percent of the total injected. Differences were attributed principally to differences in the quality of water injected and storage duration. Repeated injection-recovery cycles probably would result in greater recoverability. Head buildup, nearly 200 feet in one test, was a prime problem related chiefly to clogging from suspended material in the injected water and to bacterial growth at the wellbore-limestone interface. Regular backflushing was required. Total head buildup decreased as a result of acidizing the injection well. No coliforms or fecal streptococcus were noted in the recovered water. Growth of anaerobic bacteria occurred. Changes in the quality of the recovered water included decreases in concentration of dissolved organic carbon by as much as 15 mg/L (milligrams per liter), organic nitrogen by as much as 0.80 mg/L, and nitrate by as much as 0.50 mg/L. Increases were noted in ammonia by 0.40 mg/L, and iron by as much as 0.60 mg/L. These changes are consistent with the presence of an anaerobic bacterial ecosystem.

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USGS1982

Hydrologic data from monitoring of saline-water intrusion in the Cape Coral area, Lee County, Florida

As a result of declining water levels and saline-water intrusion in the Cape Coral area, the U.S. Geological Survey in cooperation with the City of Cape Coral established a monitoring well network in Cape Coral and adjacent areas in 1978-79. The network was designed to provide indication of lateral movement of saline water in the upper part of the Hawthorn Formation; to provide trends in water levels; and to provide background data from: (1) the aquifer in the upper part of the Hawthorn Formation; (2) the aquifer in the lower part of the Hawthorn Formation and upper part of the Tampa Limestone; and (3) the surficial aquifer. The monitoring well network consists of 77 wells. Data collected in this network since 1978, as well as data collected from selected wells in the network prior to 1978, are compiled in this report. These data include water-quality data from 69 wells, water-level data from 29 wells, and lithologic logs from 18 wells. Other data compiled in this report include municipal pumpage and rainfall data supplied by the City of Cape Coral.

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USGS1977

Municipal water supplies in Lee County, Florida, 1974

In response to population growth, demands for water in Lee County have increased markedly in the past 5 years. In 1974, the 10 largest municipal water-supply systems in the county supplied the water needs of about 170,000 people. Ongoing water-resources investigations are aimed at providing responsible and interested parties with the necessary information to effectively manage and utilize the water resources of Lee County. Raw freshwater is supplied to the municipal water plants from the Caloosahatchee River and from three ground-water sources: the watertable aquifer, the uppermost part of the Tamiami Formation and the upper part of the Hawthorn Formation. Saline water, which is used after desalting, is supplied from two permeable zones, one in the lower part of the Hawthorn Formation and the other in the Suwannee Limestone. The total quantity of raw water pumped during 1974 was 5,700 million gallons, an increase of 54 percent from 1970 pumpage. The largest source of supply in use is the water-table aquifer and the smallest are the lower part of the Hawthorn Formation and the Suwannee Limestone. Increased pumping from the upper part of the Hawthorn for public supply and irrigation has resulted in progressively declining water levels, an indication that the supply of water from this source is limited. After expansion of the Sanibel Island and Cape Coral water-supply systems, increasing demands will be placed on the water-bearing stratum in the lower part of the Hawthorn Formation and the Suwannee Limestone. At the present time (1976), there is limited information on the quantity and quality of water available in these saline-water-bearing strata beneath Lee County. The quality of fresh ground water in areas unaffected by intrusion of saline water, generally meets all the recommended limits of the Environmental Protection Agency. The chemical treatment processes utilized by water water plants in the county are generally effective in producing finished water that meets EPA preliminary drinking water standards. The rapid increase in water demands over the last 5 years, together with an anticipated accelerated demand in the future, indicates a necessity for expanding the knowledge of the water resources of the county. Specifically, additional efforts will be required to determine the yield characteristics of and quality of water in each of the groundwater sources in Lee County.

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USGS1977

Saline-water intrusion related to well construction in Lee County, Florida

Ground water is the principle source of water supply in Lee County, Florida where an estimated 30,000 wells have been drilled since 1990. These wells ranges in depth from about 10 to 1,240 feet and tap the water table aquifer or one or more of the artesian water-bearing units or zones in the Tamiami Formation, the upper part of the Hawthorn Formation, the lower part of the Hawthorn Formation and the Tampa Limestone and the Suwannee Limestone. Before 1968, nearly all wells were constructed with galvanized or black iron pipe. Many of these wells are sources of saline-water intrusion into freshwater-bearing zones. The water-bearing zones in the lower part of the Hawthorn Formation, Tampa Limestone, and Suwannee Limestone are artesian-they have higher water levels and usually contain water with a higher concentration of dissolved solids than do the aquifers occurring at shallower depths. The water from these deeper aquifers generally range in dissolved solids concentration from about 1,500 to 2,400 mg/L, and in chloride from about 500 to 1,00 mg/L. A maximum chloride concentration of 15,200 mg/L has been determined. Few of the 3,00 wells estimated to have been drilled to these zones contain sufficient casing to prevent upward flow into overlaying water-bearing zones. Because of water-level differentials, upward movement and lateral intrusion of saline water occurs principally into the upper part of the Hawthorn Formation where the chloride concentrations in water unaffected by saline-water intrusion ranges from about 80 to 150 mg/L. Where intrusion from deep artesian zones has occurred, the chloride concentration in water from the upper part of the Hawthorn Formation ranges from about 300 to more than 2,100 mg/L. Surface discharges of the saline water from wells tapping the lower part of the Hawthorn Formation and the Suwannee Limestone also had affected the water-table aquifer which normally contains water with 10 to 50 mg/L of chloride. In one area, the chloride concentration in water from the water table aquifer ranged from 200 to 590 mg/L as a result of intrusion. In areas adjacent to tidal-water bodies, the water table aquifer contains water that is very saline, Where the wells in such areas have been constructed with metal casings, the metal corrodes when exposed to the saline water, and many ultimately develop holes. This permits saline water to leak into the well where the water level in the well is lower than the water table. The intrusion of saline water from the water-table aquifer into the upper part of the Hawthorn Formation is a major problem in parts of Cape Coral. Withdrawal of water from the upper part of the Hawthorn Formation has caused water levels to decline below the lowest annual position of the water table, so that downward leakage is perennial. In some coastal areas, wells that tap the upper part of the Hawthorn Formation contain water whose chloride concentration is as much as 9,500 mg/L. Upward leakage of saline water from the deep artesian aquifers and downward leakage of saline water from the water-table aquifer can be prevented by proper well construction.

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USGS1976

High-resolution seismic reflection profiling for mapping shallow aquifers in Lee County, Florida

High-resolution continuous seismic reflection profiling equipment was utilized to define the configuration of sedimentary layers underlying part of Lee County, Florida. About 45 miles (72 kilometers) of profile were made on the Caloosahatchee River Estuary and San Carlos Bay. Two different acoustic energy sources, a high resolution boomer and a 45-electrode high resolution sparker, both having a power input of 300 joules, were used to obtain both adequate penetration and good resolution. The seismic profiles show that much of the strata of middle Miocene to Holocene age apparently are extensively folded but not faulted. Initial interpretations indicate that: (1) the top of the Hawthorn Formation (which contains the upper Hawthorn aquifer) has much relief due chiefly to apparent folding; (2) the limestone, sandstone, and unconsolidated sand and phosphorite, which together compose the sandstone aquifer, appear to be discontinuous; (3) the green clay unit of the Tamiami Formation contains large scale angular beds dipping eastward; and (4) numerous deeply cut alluvium-filled paleochannels underlie the Caloosahatchee River. (Woodard-USGS)

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USGS1975

A reconnaissance of hydrogeologic conditions in Lehigh Acres and adjacent areas of Lee County, Florida

Lehigh Acres, a residential community with a population of about 13,500 and comprising an area of about 94 square miles (243 square kilometres) in the eastern part of Lee County, has been under development since 1954. Prior to development the area was poorly drained. By 1974, more than 150 miles (241 kilometres) of drainageways had been constructed to drain the area. The water-bearing formations underlying Lehigh Acres include the water-table, sandstone, lower Hawthorn, and Suwannee aquifers. The water-table aquifer is usually not more than 30 feet (9 metres) thick; it contains water of relatively good quality, except for iron and color. Water levels in this aquifer probably have been affected by construction of drainage canals. The sandstone aquifer, used extensively throughout the area as a source of water supply usually contains water of good quality although the water is hard and in places may contain concentrations of dissolved solids and iron which exceed the recommended limits of the U.S. Public Health Service and the State of Florida for drinking water. The lower Hawthorn and Suwannee aquifers, usually encountered at depths between 440 and 850 feet (135 and 262 metres), contains water with relatively high concentrations of sodium, sulfate, chloride, and dissolved solids. Three streams, the Orange River, Hickey Creek, and Bedman Creek and the canals connected to them, provide drainage of the area. Except for the Orange River, where the water is of good chemical quality, little is known of the water quality. Similarly, little information is available on stream discharge except for the Orange River where the average annual discharge was 41.1 cubic feet per second (11.6 cubic metres per second) between 1935-46. Most lakes and ponds in Lehigh Acres are hydraulically connected to the water-table aquifer such that factors which affect one also affect the other. Theoretical drawdown curves indicate that the drainage canals may affect ground-water levels to a distance of 6,000 feet (1,800 metres) under certain conditions. Leeland Lake, the only known sinkhole lake in Lee County, is about 208 feet (64 metres) deep and contains water more nearly similar to the sandstone aquifer, although the lake may by hydraulically connected to both the water-table and sandstone aquifers.

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USGS1956

Interim report on surface water resources and quality of waters in Lee County, Florida

The purpose of this report is to provide such information on the surface-water resources of the county as inay be useful in planning for their more intensive use. This report is not intended to provide final answers to all questions concerning the occurrence of surface water in the c:ounty; because of the paucity of information on the various streams in the area. However, as an initial step it should prove valuable in the formulation of plans for the future.

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