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R. M. Spechler

Publications and source records attributed to R. M. Spechler.

At least 19 recordsLinked to original sources
USGS2001

Using multiple geochemical tracers to characterize the hydrogeology of the submarine spring off Crescent Beach, Florida

A spectacular submarine spring is located about 4 km east of Crescent Beach, FL, in the Atlantic Ocean. The single vent feature of Crescent Beach Spring provides a unique opportunity to examine onshore–offshore hydrogeologic processes, as well as point source submarine ground water discharge. The Floridan aquifer system in northeastern Florida consists of Tertiary interspersed limestone and dolomite strata. Impermeable beds confine the water-bearing zones under artesian pressure. Miocene and younger confining strata have been eroded away at the vent feature, enabling direct hydrologic communication of Eocene ground water with coastal bottom waters. The spring water had a salinity of 6.02, which was immediately diluted by ambient seawater during advection/mixing. The concentration of major solutes in spring water and onshore well waters confirm a generalized easterly flow direction of artesian ground water. Nutrient concentrations were generally low in the reducing vent samples, and the majority of the total nitrogen species existed as NH 3 . The submarine ground water tracers, Rn-222 (1174 dpm l −1 , dpm), methane (232 nM) and barium (294.5 nM) were all highly enriched in the spring water relative to ambient seawater. The concentrations of the reverse redox elements U, V and Mo were expectedly low in the submarine waters. The strontium isotope ratio of the vent water ( 87 Sr/ 86 Sr=0.70798) suggests that the spring water contain an integrated signature indicative of Floridan aquifer system ground water. Additional Sr isotopic ratios from a series of surficial and Lower Floridan well samples suggest dynamic ground water mixing, and do not provide clear evidence for a single hydrogeologic water source at the spring vent. In this karst-dominated aquifer, such energetic mixing at the vent feature is expected, and would be facilitated by conduit and fractured flow. Radium isotope activities were utilized to estimate flow-path trajectories and to provide information on potential travel times between an onshore well and the spring. Using either 223 Ra and 224 Ra or 228 Ra, and qualifying this approach with several key assumptions, estimates of water mass travel times from an upper Floridan well in Crescent Beach to the submarine vent feature (distance=4050 m) are in the order of ∼0.01–0.1 m min −1 .

Florida↗
USGS1997

The relation between hydrogeology and water quality of the Lower Floridan Aquifer in Duval County, Florida, and implications for monitoring movement of saline water

The hydrogeology of the Upper zone of the Lower Floridan aquifer and its relation to water quality were evaluated during a 3-year (1993-96) study. The Floridan aquifer system, a carbonate aquifer system composed of the Upper Floridan aquifer, a middle semi-confining unit, and the Lower Floridan aquifer, is the major source of water supply in northeastern Florida. The Lower Floridan aquifer is further subdivided into the Upper zone, a semi-confining unit, and the Fernandina permeable zone. As a result of increased withdrawals, heads in the aquifer system have declined and at the same time chloride concentrations have increased in the water from many wells in Duval County. A better understanding of the sources of and pathways for movement of brackish water is needed so that water managers can monitor the movement of brackish water and plan future water development. Most of the wells in Duval County deeper than 900 feet penetrate the Upper Floridan aquifer and the Upper zone of the Lower Floridan aquifer. Transmissivity estimates for these zones range from 2,000 to 194,000 feet squared per day. Permeability in the Upper zone of the Lower Floridan aquifer is primarily related to secondary porosity developed along bedding planes, joints, and fractures as a result of paleokarst processes. The Upper zone is about 300 to 500 feet thick in Duval County, based on the geophysical logs of about 40 wells ranging in depth from about 1,000 to 2,200 feet. In some areas the Upper zone has a single flow zone, but in other areas, two distinct flow zones are apparent. Water samples collected during this study confirm the continued increase in chloride concentrations in both the Upper Floridan aquifer and the Upper zone of the Lower Floridan aquifer. Most of the observed increases are in the eastern part of the county, but a pattern in the locations of wells yielding water with chloride increases is not discernible. In some areas, zones bearing brackish water are underlain by zones of fresher water, but in other areas, fresher water was not found beneath the brackish water. A single fracture or solution feature was the source of brackish water in several wells. The most likely source of brackish water to the Upper zone of the Lower Floridan aquifer is the underlying Fernandina permeable zone, which contains freshwater in the western part of the county but saline water in the eastern part. The pathways for movement of saline water are interconnecting vertical and horizontal fracture or solution zones probably developed along paleokarst features that are not mappable from the land surface; therefore, a conventional monitor-well network probably would not provide early warning of saline-water intrusion. Continued monitoring of water-quality trends in water-supply wells, combined with collection of additional surface and borehole geophysical data, can provide an increased understanding of the movement of brackish water in the Floridan aquifer system.

Florida↗
USGS1996

Detection and quality of previously undetermined Floridan aquifer system discharge to the St. Johns River, Jacksonville, to Green Cove Springs, northeastern Florida

Potentiometric surface maps of the Upper Floridan aquifer show two depressions around the St. Johns River frm the city of Jacksonville south toward Green Cove Springs. These depressions, depending on their locations, are the result of withdrawals from agricultural, industrial, domestic and public-supply wells, diffuse upward leakage, and discharge from springs. Submerged springs that discharge into the St. Johns River between Jacksonville and Green Cove Springs have been thought to exist, but locating and evaluating these springs had not been attempted before this investigation. Thermal infrared imagery, seismic reflection, and numerous interviews with local residents were used to locate springs. An airborne thermal infrared survey was conducted along a section of the St. Johns River in northeastern Florida during February 1992 to detect possible sources of ground-water discharge to the river. An infrared image displayed one thermal anomaly in the St. Johns River which is associated with a previously unknown spring discharge from the Floridan aquifer system. Thermal anomalies also were observed at six locations where municipal facilities discharge treated wastewater to the river. Results of seismic reflection surveys indicate the presence of collapse and other karst features underlying the St. Johns River. These features indicate that the surficial deposits and the Hawthorn Formation that underlie the river probably do not consist of continuous beds. The collapse or deformation of the Hawthorn Formation or the presence of permeable sediment of localized extent could create zones of relatively high vertical leakance. This could provide a more direct hydraulic connection between the Upper Floridan aquifer and the river. Water samples collected from the only submerged spring in the St. Johns River within the Jacksonville-Green Cove Springs reach indicate that the source of the water is the Floridan aquifer system. Chloride and sulfate concentrations were 12 and 340 milligrams per liter, respectively. Specific conductance was 826 microsiemens per centimeter and the temperature of the water discharging from the spring was 25.1 degrees Celsius. The ratio of 87 Strontium/86 Strontium also indicates that the springwater has been in contact with rock materials of Eocene age, providing additional evidence that the springwater is derived from the Floridan aquifer system.

Water-Resources Investigations Report↗
USGS1995

Estimated discharge and chemical-constituent loading from the upper Floridan aquifer to the lower St. Johns River, northeastern Florida, 1990-91

The lower St. Johns River, a 101-mile long segment of the St. Johns River, begins at the confluence of the Ocklawaha River and ends where the river discharges into the Atlantic Ocean at Mayport. The St. Johns River is affected by tides as far upstream as Lake George, 106 miles from the mouth. Saltwater from the ocean advances inland during each incoming tide and recedes during each outgoing tide. The chemical quality of the lower St. Johns River is highly variable primarily because of the inflow of saltwater from the ocean, and in some areas, from the discharge of mineralized ground water. Three hydrogeologic units are present in the study area: the surficial aquifer system, the intermediate confining unit, and the Floridan aquifer system. The surficial aquifer system overlies the intermediate confining unit and consists of deposits containing sand, clay, shell, and some limestone and dolomite. The intermediate confining unit underlies all of the study area and retards the vertical movement of water between the surficial aquifer system and the Floridan aquifer system. The intermediate confining unit consists of beds of relatively low permeability sediments that vary in thickness and areal extent and can be breached by sinkholes, fractures, and other openings. The Floridan aquifer system primarily consists of limestone and dolomite. The quality of water in the Upper Floridan aquifer varies throughout the study area. Dissolved solids in water range from about 100 to more than 5,000 milligrams per liter. Chloride and sulfate concentrations in water from the Upper Floridan aquifer range from about 4 to 3,700 milligrams per liter and from 1 to 1,300 milligrams per liter, respectively. The rate of leakage through the intermediate confining unit is controlled by the leakance coefficient of the intermediate confining unit and by the head difference between the Upper Floridan aquifer and the surficial aquifer system. The total ground-water discharge from the Upper Floridan aquifer to the St. Johns River within the lower St. Johns River drainage basin, based on the potentiometric surface of the Upper Floridan aquifer in September 1990, was estimated to be 86 cubic feet per second. Total estimated ground-water discharge to the lower St. Johns River in September 1991, when heads in the Upper Floridan aquifer averaged about 4 feet higher than in 1990, was 133 cubic feet per second. The load of dissolved-solids that discharged from the Upper Floridan aquifer into the lower St. Johns River on the basis of September 1990 heads is estimated to be 47,000 tons per year. Estimated chloride and sulfate loads are 18,000 and 9,500 tons per year, respectively. Dissolved-solids, chloride, and sulfate loads discharging into the lower St. Johns River are estimated to be 81,000, 39,000, and 15,000 tons per year, respectively, on the basis of September 1991 heads.

Florida↗
USGS1994

Potentiometric surface of the upper Floridan Aquifer in the St. Johns River Water Management District and vicinity, Florida, May 1994

This map depicts the potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity for May 1994. The map is based on water-level measurements made at approximately 1,000 wells and several springs. Data on the map were contoured using 5-foot contour intervals in most areas. The potentiometric surface of this karstic aquifer generally reflects land surface topography. Potentiometric surface highs often correspond to topographic highs, which are areas of surficial recharge to the Upper Floridan aquifer. Springs within topographic lows along with areas of more diffuse upward leakage are natural zones of discharge. Municipal, agricultural, and industrial withdrawals have lowered the potentiometric surface in some areas. The potentiometric surface ranged from 125 feet above sea level in Polk County to 32 feet below sea level in Nassau County. Water levels in May 1994 generally were 0 to 3 feet lower than those measured in May 1993. Water levels in May 1994 in northeast Florida generally were 0 to 3 feet higher than in September 1993, except in the lower St. Johns River basin, where water levels were 0 to 4 feet lower than in September 1993. In the rest of the mapped area, water levels in May 1994 generally were 0 to 4 feet lower than those measured in September 1993.

Open-File Report↗
USGS1994

Saltwater intrusion and quality of water in the Floridan aquifer system, northeastern Florida

Saltwater intrusion is a potential threat to ground- water quality in the Floridan aquifer in Duval, Nassau, and St. Johns Counties. Five possible mechanisms of saltwater movement that could explain the increases in chloride concentrations in water in the freshwater zones of the Floridan aquifer system are: (1) unflushed pockets of relic seawater, (2) upward leakage of saltwater through failed, uncased, or improperly plugged or constructed wells, (3) lateral movement of saltwater from the north- eastern Florida coast, (4) upconing of saltwater from below pumped wells, and (5) saltwater movement into freshwater zones due to thinning, or breaching by joints, fractures, collapse features, or possibly by faults, of the overlying semiconfining beds. Total ground-water use in the study area increased more than 40 percent between 1965 and 1988, with approximately 90 percent of the water being with- drawn from the Floridan aquifer system. Pumping to satisfy this increase in water use resulted in a decline of the potentiometric surface, thus in- creasing the potential for saltwater movement upward into freshwater zones. The potential for saltwater intrusion is expected to increase as population growth continues and greater demands are placed on ground-water resources. Possible water-management strategies that could reduce this potential threat include: minimizing well depths, installation of new well fields in areas where the thickness of the freshwater lens is greatest, reducing drawdowns in wells fields and other areas where saltwater in- trusion could be occurring, and plugging the lower parts of some of the deeper wells.

Water-Resources Investigations Report↗
USGS1987

Potentiometric surface of the upper Floridan aquifer in the St. Johns River Water Management District and vicinity, Florida, September 1986

This map shows the potentiometric surface of the Upper Floridan aquifer in the St. Johns River Water Management District and vicinity for September 1986. The Upper Floridan aquifer is the principal source of potable water in the area. Water level measurements were made on approximately 1,000 wells and on several springs. The potentiometric surface is shown mostly by 5-ft contour intervals. The potentiometric surface ranged from 129 ft above sea level in Polk County to 88 ft below sea level in Nassau County. The steep cone of depression of the potentiometric surface in the Fernandina Beach area of Nassau County is caused by large withdrawal of groundwater for industrial use. Many water levels in the district were equal to or lower than water levels of September 1985. Declines of as much as 2 ft from September 1985 levels were common throughout the district in response to a decline in rainfall and an increase in pumpage. The largest decline from September 1985 potentiometric surface level was 8 ft, occurring in Indian River County. Levels in many wells approached, and in a few wells exceeded, record lows. (USGS)

Open-File Report↗
USGS1983

Appraisal of the interconnection between the St Johns River and the surficial aquifer, east-central Duval County, Florida

The proposed deepening of the navigation channel in the St. Johns River to about 46-48 feet below sea level (45 feet below mean low water) may breach up to 11 feet of limestone unit of the lower part of the surficial aquifer along a 25-mile channel. The limestone supplies water to numerous domestic wells along the river in the Jacksonville area. Recent channel improvements to about 39 feet below sea level have already breached the limestone at many locations. Where breaching has not yet occurred, less than 1 to 6 feet of undifferentiated sediments overlie the limestone. These sediments, consisting predominantly of sand, are generally too permeable to form an effective confining layer. Chloride concentrations determined from water in wells tapping the limestone unit range from 8 to 6,600 milligrams per liter. However, chloride concentrations in water from wells located more than 500 feet from the river, were generally less than 30 milligrams per liter. The proposed dredging operation is not expected to alter significantly the present hydrologic system. The current position of the interface most likely represents conditions that will be present after future channel improvements. (USGS)

Florida↗
USGS1980

Configuration of the top of the highly permeable dolomite zone of the Floridan Aquifer, Southwest Florida Water Management District

This map report presents the configuration of the top of the highly permeable dolomite zone of the Floridan aquifer in the Southwest Florida Water Management District. The top of the highly permeable dolomite generally corresponds to the top of a thick bed of massive, hard, dark brown dolomite occurring in the Avon Park Limestone of Eocene age. The altitude of the top of the permeable dolomite varies from about 100 feet below the National Geodetic Vertical Datum of 1929 in the north to about 1 ,600 feet below the datum in the south. (Kosco-USGS)

Open-File Report↗
USGS1979

Generalized thickness of the surficial deposits above the confining bed overlying the Floridan Aquifer, Southwest Florida Water Management District

This map report presents the thickness of the surficial deposits overlying the upper confining bed of the Floridan aquifer in the Southwest Florida Water Management District. The surficial deposits range in thickness from less than 25 feet in the western part of the district to greater than 250 feet in the eastern part. The surficial deposits include sand, clayey sand, shell, and shelly marl that occur in the Holocene sand, Pleistocene marine terrace sand, and unconsolidated parts of the Fort Thompson Formation, Caloosahatchee Marl, Alachua Formation, and Bone Valley Formation. Lithologic logs and information from quarries were used in conjunction with an unpublished map prepared during an earlier investigation to compile this map at 1:250,000 scale. (Kosco-USGS)

Florida↗
USGS1979

Generalized thickness of the confining bed overlying the Floridan Aquifer, Southwest Florida Water Management District

This map presents the thickness of the confining bed overlying the Floridan aquifer in the Southwest Florida Water Management District and adjacent areas. The bed separates the surficial aquifer from the underlying Floridan aquifer. Lithologic logs and information from quarries were used in conjunction with an unpublished map to compile this map at 1:250,000 scale. Units included in the confining bed are: clay, sandy clay and marl, undifferentiated with respect to age, the Hawthorn Formation, and the unconsolidated sections of the Tampa Limestone. (Kosco-USGS)

Open-File Report↗
USGS1979

Generalized configuration of the bottom of the Floridan aquifer, Southwest Florida Water Management District

This map presents the configuration of the bottom of the Floridan aquifer in the Southwest Florida Water Management District. The bottom of the aquifer generally corresponds to the beginning of consistent intergranular evaporites occurring in either the Avon Park, Lake City, or Oldsmar Limestones of Eocene age. The altitude of the bottom of the aquifer varies from about 600 feet below the National Geodetic Vertical Datum of 1929 in the north to about 3,000 feet below the datum in the South. (Kosco-USGS)

Florida↗