Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Fluoride”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources
USGS1989

Inorganic and organic ground-water chemistry in the Canal Creek area of Aberdeen Proving Ground, Maryland

Groundwater chemical data were collected from November 1986 through April 1987 in the first phase of a 5-year study to assess the possibility of groundwater contamination in the Canal Creek area of Aberdeen Proving Ground, Maryland. Water samples were collected from 87 observation wells screened in Coastal Plain sediments; 59 samples were collected from the Canal Creek aquifer, 18 from the overlying surficial aquifer, and 10 from the lower confined aquifer. Dissolved solids, chloride, iron, manganese, fluoride, mercury, and chromium are present in concentrations that exceed the Federal maximum contaminant levels for drinking water. Elevated chloride and dissolved-solids concentrations appear to be related from contaminant plumes but also could result from brackish-water intrusion. Excessive concentrations of iron and manganese were the most extensive water quality problems found among the inorganic constituents and are derived from natural dissolution of minerals and oxide coatings in the aquifer sediments. Volatile organic compounds are present in the Canal Creek and surficial aquifers, but samples from the lower confined aquifer do not show any evidence of contamination by inorganic or organic chemicals. The volatile organic contaminants detected in the groundwater and their maximum concentrations (in micrograms/L) include 1,1,2,2- tetrachloroethane (9,000); carbon tetrachloride (480); chloroform (460); 1,1,2-trichloroethane (80); 1,2-dichloroethane (990); 1,1-dichloroethane (3.1); tetrachloroethylene (100); trichloroethylene (1,800); 1,2-trans- dichloroethylene (1,200); 1,1-dichloroethylene (4.4); vinyl chloride (140); benzene (70); and chlorobenzene (39). On the basis of information on past activities in the study area, some sources of the volatile organic compounds include: (1) decontaminants and degreasers; (2) clothing-impregnating operations; (3) the manufacture of impregnite material; (4) the manufacture of tear gas; and (5) fuels used in garages and at the air-field. The high density of most of the detected organic compounds in free-product form would have aided their movement into the aquifers by vertical sinking. The outcrop area of the upper confining unit and an area cut by a paleochannel are most susceptible to contamination because a near-surface impermeable layer is not present. (USGS)

Water-Resources Investigations Report↗
USGS1991

Hydrogeology and water quality of glacial-drift aquifers in the Bemidji-Bagley area, Beltrami, Clearwater, Cass, and Hubbard Counties, Minnesota

Unconfined and the upper confined aquifers in glacial drift are the primary sources of water in a 1,600 square-mile area including parts of Beltrami, Cass, Clearwater, and Hubbard Counties, Minnesota. The unconfineddrift aquifer consists of coarse sand and gravel in the center of the study area. The total area underlain by the unconfined-drift aquifer is approximately 550 square miles. The unconfined aquifer ranges in thickness from 0 to 130 feet, and is greater than 20 feet thick over an area of 280 square miles. On the basis of scant data, the transmissivity of the unconfined aquifer ranges from less than 70 feet squared per day in the south and west to greater than 8,900 feet squared per day in an area west of Bemidji. Well yields from 10 to 300 gallons per minute are possible in some areas. The unconfined and upper confined-drift aquifers are separated by a fine-grained confining unit of till or lake deposits. The thickness of the upper confined-drift aquifer ranges from 0 to 60 feet in the Bemidji area. On the basis of specific-capacity and aquifer-thickness data, and results of model simulations, the transmissivity of the upper confined-drift aquifer ranges from less than 100 feet squared per day in the south and west parts of the aquifer to about 12,800 feet squared per day in the area around Bemidji. Well yields of 10 to 2,100 gallons per minute are possible in some areas. The direction of ground-water flow in both unconfined and upper confineddrift aquifers is toward the Mississippi and Clearwater Rivers. These rivers are the major discharge points for both aquifers. Ground-water divides, which separate the ground-water flow systems that discharge to these rivers, are approximately coincidental with surface-water divides between the rivers. Water from both aquifers generally is of the calcium bicarbonate type and is very hard, averaging 309 and 267 milligrams per liter as CaCO 3 from confined and unconfined-drift aquifers, respectively. Water from both aquifers generally is suitable for drinking, crop irrigation, and most other uses. Concentrations of ammonia, boron, chromium, iron, manganese, and phenols, however, locally exceed recommended limits for drinking water (Minnesota Pollution Control Agency, 1988). Longer residence time and leakage through glacial till is believed to cause higher concentrations of common inorganic constituents in water from confined-drift aquifers than concentrations in water from the unconfined-drift aquifer. Elevated concentrations of nutrients, chloride, and phenols in the unconfined-drift aquifer may be related to land-use practices. Statistical comparisons of common chemical constituents in water from wells completed in the unconfined-drift aquifer in several land-use areas suggest that concentrations of many constituents and physical properties are generally greater for wells in areas of commercial and residential land-use than for wells in areas of agriculture or forest land-use. These constituents include ammonia plus organic nitrogen, phosphorus, calcium, sodium, potassium, chloride, sulfate, silica, dissolved solids, and specific conductances. The mean values of ammonia nitrogen, magnesium, and fluoride are generally greater for wells in commercial land-use type areas than for wells in forested and agricultural land-use type areas. The mean concentration of nitrogen (N0 2 + NO 3 , dissolved) is generally greater for wells in residential land-use type areas than for wells in forested and agricultural land-use type areas. The Kruskil-Wallis test, a nonparametric that for 12 of the 21 constituents sampled in groups in the unconfined-drift aquifer, a of these constituents and land use was found statistical technique, indicated common in all land-use type relation between the concentration to be statistically significant.

Minnesota↗
USGS1990

Geohydrology and water quality of Kalamazoo County, Michigan, 1986-88

Thick, glacial sand and gravel deposits provide most ground-water supplies in Kalamazoo County. These deposits range in thickness from 50 to about 600 feet in areas that overlie buried bedrock valleys. Most domestic wells completed at depths of less than 75 feet in the sands and gravels yield adequate water supplies. Most industry, public supply, and irrigation wells completed at depths of 100 to 200 feet yield 1,000 gallons per minute or more. The outwash plains include the most productive of the glacial aquifers in the county. The Coldwater Shale of Mississippian age, which underlies the glacial deposits in most of the county, usually yields only small amounts of largely mineralized water. Ground-water levels in Kalamazoo County reflect short- and long-term changes in precipitation and local pumpage. Ground-water levels increase in the spring and decline in the fall. Ground-water recharge rates, for different geologic settings, were estimated from ground-water runoff to the streams. Recharge rates ranged from 10.86 to 5.87 inches per year. A countywide-average ground-water recharge rate is estimated to be 9.32 inches per year. Chemical quality of precipitation and dry fallout at two locations in Kalamazoo County were similar to that of other areas in the State. Total deposition of dissolved sulfate is 30.7 pounds per acre per year, of total nitrogen is 13.2 pounds per acre per year, and of total phosphorus is 0.3 pounds per acre per year. Rainfall and snow data indicated that the pH of precipitation is inversely proportional to its specific conductance. Water of streams and rivers of Kalamazoo County is predominately of the calcium bicarbonate type, although dissolved sulfate concentrations are slightly larger in streams in the southeastern and northwestern parts of the county. The water in most streams is hard to very hard. Concentrations of dissolved chloride in streams draining urban-industrial areas are slightly larger than at other locations. Concentrations of total nitrogen and total phosphorus in streams are directly proportional to streamflow. Except for elevated concentrations of iron, none of the trace elements in streams exceeded maximum contaminant levels for drinking water established by the U.S. Environmental Protection Agency. Pesticides were detected in some streams. Ground water in the surficial aquifers is of the calcium bicarbonate type, although sodium, sulfate, and chloride ions predominate at some locations. Specific conductance and hardness and concentrations of total dissolved-solids slightly exceed statewide averages. Concentrations of dissolved sodium and dissolved chloride in 6 wells were greater than most natural ground waters in the State, indicating possible contamination from road salts. Water samples from 6 of the 46 wells sampled contained concentrations of total nitrate as nitrogen greater than 10.0 milligrams per liter. Elevated concentrations of total nitrate as nitrogen in water from wells in rural-agricultural areas probably are related to fertilizer applications. Results of partial chemical analyses by the Michigan Department of Public Health indicates specific conductance, and concentrations of hardness, dissolved fluoride, and total iron are fairly uniform throughout the county. Concentrations of dissolved sodium, dissolved chloride, and total nitrate as nitrogen differed among townships. Pesticides were detected in water from only one well. Water from five wells contained volatile organics. A map of susceptibility of ground water to contamination in Kalamazoo County was developed using a system created by the U.S. Environmental Protection Agency. Seven geohydrologic factors that affect and control ground-water movement are mapped and composited onto a countywide map. All seven factors have some effect on countywide susceptibility, but the most important factors are depth to water and composition of the materials above the aquifer.

Michigan↗
USGS1994

Ground-water flow and quality, and geochemical processes, in Indian Wells Valley, Kern, Inyo, and San Bernardino counties, California, 1987-88

An existing water-quality data base for the 300- square-mile Indian Wells Valley was updated by means of chemical and isotopic analysis of ground water. The wide range in measured concentrations of major ions and of minor constituents such as fluoride, borate, nitrate, manganese, and iron is attributed to geochemical reactions within lacustrine deposits of the valley floor. These reactions include sulfate reduction accompanied by generation of alkalinity, precipitation of carbonates, exchange of aqueous alkaline-earth ions for sodium on clays, and dissolution of evaporite minerals. Differences in timing and location of recharge, which originates primarily in the Sierra Nevada to the west, and evapotranspiration from a shallow water table on the valley floor result in a wide range in ratios of stable hydrogen and oxygen isotopes. As ground water moves from alluvium into lustrine deposits of the ancestral China Lake, dissolved-solids concen- trations increase from about 200 to more than 1,000 milligrams per liter; further large increases to several thousand milligrams per liter occur beneath the China Lake playa. Historical data show an increase during the past 20 years in dissolved- solids concentration in several wells in the principal pumping areas at Ridgecrest and between Ridgecrest and Inyokern. The increase apparently is caused by induced flow of saline ground water from nearby China, Mirror, and Satellite Lakes. A simplified advective-transport model calculates ground-water travel times between parts of the valley of at least several thousand years, indi- cating the presence of old ground water. A local ground-water line and an evaporation line estimated using isotopic data from the China Lake area inter- sect at a delta-deuterium value of about -125 permil. This indicates that late Pleistocene recharge was 15 to 35 permil more negative than current recharge.

Water-Resources Investigations Report↗
USGS1993

Geohydrology and quality of shallow ground water at and near the Old Laurel County and G.C. Singleton landfills, Laurel County, Kentucky

Between 1969 and 1983, solid and hazardous waste was deposited at the Old Laurel County and G.C. Singleton Landfills that were developed on a bench created by strip mining for coal. Water-level data from eight monitoring wells indicate that the general direction of groundwater flow in the shallow aquifer is toward Slate Lick, which is at a lower altitude than the landfills. Analyses of water samples from these wells indicate that the water quality near the landfills is similar to that expected in coal strip-mined areas. The pH of groundwater ranged from 4.6 to 6.2 and indicates acidic conditions. Elevated values of specific conductance in groundwater near the landfills may indicate the effects of landfill leachate or acid-mine drainage. The groundwater samples also contained high concentrations of dissolved constituents commonly associated with acid-mine drainage such as aluminum, iron, manganese, sulfate, and zinc. A relatively high concentration of fluoride, 4.5 mg/L, in water from one well may be related to landfill leachate. Except for 3,4-dichloro-benzoic acid, organic constituents were not detected in the groundwater samples. However, because of the widespread use of chemicals containing 3,4-dichloro-benzoic acid, the source of this constituent in the shallow aquifer system near the landfills cannot be determined.

Kentucky↗
USGS1993

Water resources of Taos County, New Mexico

In Taos County, ground water generally is unconfined and moves toward the Rio Grande or perennial streams. Water quality is good except in some areas where water has high values of specific conductance and hardness and contains high concentrations of dissolved solids and fluoride. Most wells are completed in alluvial sediments of Quaternary and Tertiary age in the Costilla Plains. A few wells are completed in basalt of the Taos Plateau and in alluvium of stream channels in the Sangre de Cristo Mountains. Depths to water in wells range from less than 1 to 1,080 feet below land surface. Well yields range from 1 to 3,000 gallons per minute. Water levels in wells in Sunshine Valley dropped 5 to 50 feet between 1955 and 1970. Ground-water irrigation has since declined and water levels have risen. Surface-water records show the county is a net producer of water. The average discharge gained in the Rio Grande as it flows through the county was 271,700 acre-feet per year for water years 1931-89. The highest mean monthly discharge occurs in May or June due to snowmelt runoff. Water quality ranges from good in upstream reaches to fair in lower reaches. Surface water was the source for 93 percent of water withdrawn in 1990, but ground water was used for all public supply, domestic, and industrial purposes. The largest water use is irrigation. About 28,500 acres were irrigated in 1990; alfalfa, native pasture, and planted pasture accounted for 91 percent of this acreage.

New Mexico↗
USGS1994

Hydrogeologic characterization of a proposed landfill expansion in Pickens County near Easley, South Carolina

This report presents the results of a hydrogeologic study in the Piedmont physiographic province of South Carolina to obtain geologic, hydrologic, and water-quality data from the site of a proposed landfill expansion in Pickens County near Easley, South Carolina. The geology of the study area is typical of the Piedmont region. The unconsolidated regolith on the site is soil and saprolite, which is a product of the weathered parent rock. The soil ranges in thickness from about 5 to 20 feet. The saprolite ranges in thickness from about 5 to 134 feet. The most abundant parent rock type in the area is a biotite gneiss. Ground- and surface-water data were collected at the site. Slug tests on the saprolite indicate a mean hydraulic conductivity of 3 x 0.000003 feet per second. Transmissivity ranges from 12 to 27 cubic feet per day per feet (squared per day). The ground-water velocity for the site ranges from 3 to 6 feet per year. The closest major stream to the site is Golden Creek. Based on low-flow data for Golden Creek, the estimated minimum 7 consecutive day flow that has a recurrence interval of 10 years (7Q10) at station 02186102 is 2.4 cubic feet per second. Water samples were collected from five monitoring wells at the proposed landfill expansion site and from one stream adjacent to the expansion site. Measured pH units ranged from 5.5 to 8.1, and alkalinity concentrations ranged from 5.1 to 73 milligrams per liter as CaCO3. Other water- quality data obtained included temperature and specific conductance, and 5-day BOD (biochemical oxygen demand), bicarbonate, ammonia-nitrogen, nitrite-nitrogen, nitrite plus nitrate, organic carbon, calcium, magnesium, sodium, potassium, chloride, sulfate, fluoride, and selected trace metal concentrations.

South Carolina↗
USGS1994

Quality-assurance results for routine water analysis in US Geological Survey laboratories, water year 1991

The US. Geological Survey operates a quality- assurance program based on the analyses of reference samples for the National Water Quality Laboratory in Arvada, Colorado, and the Quality of Water Service Unit in Ocala, Florida. Reference samples containing selected inorganic, nutrient, and low ionic-strength constituents are prepared and disguised as routine samples. The program goal is to determine precision and bias for as many analytical methods offered by the participating laboratories as possible. The samples typically are submitted at a rate of approximately 5 percent of the annual environmental sample load for each constituent. The samples are distributed to the laboratories throughout the year. Analytical data for these reference samples reflect the quality of environmental sample data produced by the laboratories because the samples are processed in the same manner for all steps from sample login through data release. The results are stored permanently in the National Water Data Storage and Retrieval System. During water year 1991, 86 analytical procedures were evaluated at the National Water Quality Laboratory and 37 analytical procedures were evaluated at the Quality of Water Service Unit. An overall evaluation of the inorganic (major ion and trace metal) constituent data for water year 1991 indicated analytical imprecision in the National Water Quality Laboratory for 5 of 67 analytical procedures: aluminum (whole-water recoverable, atomic emission spectrometric, direct-current plasma); calcium (atomic emission spectrometric, direct); fluoride (ion-exchange chromatographic); iron (whole-water recoverable, atomic absorption spectrometric, direct); and sulfate (ion-exchange chromatographic). The results for 11 of 67 analytical procedures had positive or negative bias during water year 1991. Analytical imprecision was indicated in the determination of two of the five National Water Quality Laboratory nutrient constituents: orthophosphate as phosphorus and phosphorus. A negative or positive bias condition was indicated in three of five nutrient constituents. There was acceptable precision and no indication of bias for the 14 low ionic-strength analytical procedures tested in the National Water Quality Laboratory program and for the 32 inorganic and 5 nutrient analytical procedures tested in the Quality of Water Service Unit during water year 1991.

Water-Resources Investigations Report↗
USGS1995

Reconnaissance of ground-water quality in the North Platte Natural Resources District, western Nebraska, June-July 1991

One-hundred twenty wells completed in unconfined Quaternary alluvial, Ogallala, Arikaree, Brule fractured, sand and confined Chadron and undifferentiated Cretaceous water-bearing units were sampled in June and July 1991 to characterize the quality of ground water in the study area. More than 75 percent of the water samples had nitrate and nitrite as nitrogen concentrations equal to or less than 6.0 milligrams per liter. Samples from six wells completed in Quaternary alluvial and Brule fractured water-bearing units exceeded the U.S. Environmental Protection Agency Maximum Contaminant Level of 10 milligrams per liter nitrate and nitrite as nitrogen. Water from several wells completed in Quaternary alluvial and the Brule water-bearing units had detectable concentrations of alachlor, atrazine, deethylatrazine, or prometon. Major element concentrations in water from 44 wells indicated that the water-bearing units had distinct chemistry. Water from unconfined water- bearing units generally was a calcium bicarbonate type and water from the confined water-bearing units generally was a sodium bicarbonate type. Measurements of pH and concentrations of dissolved solids, sulfate, chloride, fluoride, arsenic, beryllium, manganese, adjusted gross alpha activities, radon, and uranium in ground water exceeded final or proposed U.S. Environmental Protection Agency Maximum Contaminant Levels or Secondary Maximum Contaminant Levels.

Water-Resources Investigations Report↗
USGS1995

Geohydrology and water quality of stratified-drift aquifers in the Saco and Ossipee River basins, east-central New Hampshire

Stratified-drift aquifers discontinuously underlie 152.5 square miles of the Saco and Ossipee River Basins, which have a total drainage area of 869.4 square miles. Saturated thicknesses of stratified drift in the study area are locally greater than 280 feet, but generally are less. Transmissivity locally exceeds 8,000 feet squared per day but are generally less. About 93.6 square miles, or 10.8 percent of the study area, are identified as having transmissivity greater than 1,000 feet squared per day. The stratified-drift aquifer in Ossipee, Freedom, Effingham, Madison, and Tamworth was analyzed for the availability of ground water by use of transient simulations and a two-dimensional, finite-difference ground-water-flow model. The numerical -model results indicate that potential available water amounts in this aquifer are 7.72 million gallons per day. Sample results of water- quality analyses obtained from 25 test wells and 4 springs indicated that water was generally suitable for drinking and other domestic purposes. Concen- trations of dissolved constituents in ground-water samples are less than or meet U.S. Environmental Protection Agency (USEPA)primary and secondary drinking-water regulations. Concentrations of inorganic constituents that exceeded the USEPA's secondary regulations were chloride and sodium, iron manganese, and fluoride.

Water-Resources Investigations Report↗
USGS1996

Hydrogeology and ground-water quality of glacial-drift aquifers, Leech Lake Indian Reservation, north-central Minnesota

Among the duties of the water managers of the Leech Lake Indian Reservation in north-central Minnesota are the development and protection of the water resources of the Reservation. The U.S. Geological Survey, in cooperation with the Leech Lake Indian Reservation Business Committee, conducted a three and one half-year study (1988-91) of the ground-water resources of the Leech Lake Indian Reservation. The objectives of this study were to describe the availability and quality of ground water contained in glacial-drift aquifers underlying the Reservation. Aquifers and confining units are present throughout the entire thickness of the glacial drift in the study area, which includes the Leech Lake Indian Reservation and adjacent parts of Beltrami, Hubbard, Itasca, and Cass Counties in north-central Minnesota, an area of approximately 2,145 square miles. An unconfined aquifer underlies most of the central and north-central parts of the study area. The saturated thickness of the aquifer ranges from 0 to about 105 feet. Horizontal hydraulic conductivity, estimated from 19 slug tests, ranges from 0.6 to 31 feet per day. The transmissivity of the aquifer ranges from 19 to more than 20,000 feet squared per day and is greatest in an area from west of Cass Lake to Lake Winnibigoshish. Theoretical maximum well yields range from less than 10 to about 2,000 gallons per minute. The unconfined and uppermost confined aquifers are physically and hydraulically separated by a fine-grained confining unit, consisting of till or lake deposits, that ranges in thickness from 3 to 254 feet. The thickness of the uppermost confined aquifer ranges from 5 to about 53 feet. On the basis of specific-capacity data, the transmissivity of the aquifer ranges from less than 100 feet squared per day in the northeastern and southeastern parts of the study area to about 21,000 feet squared per day near Cass Lake. Theoretical maximum well yields range from less than 10 to about 2,600 gallons per minute. Recharge to the ground-water system is predominantly from precipitation that infiltrates to the saturated zone. An analysis of four hydrographs for observation wells screened in the unconfined aquifer indicated spring recharge amounts during 1989 of 1-4 inches. Discharge from the ground-water system occurs by leakage to streams, lakes, and wetlands, evapotranspiration, withdrawals by wells, and underflow to the southeast within the Mississippi River Valley. Streamflow measurements indicate that ground-water discharge to the Mississippi River is greater in the western part of the study area between Cass Lake and Lake Winnibigoshish than in the eastern part downstream from Lake Winnibigoshish. The general regional direction of ground-water flow in the unconfined and uppermost confined aquifers is to the east and southeast. Ground-water flow is also toward the Mississippi River and the three large lakes in the study area, Lake Winnibigoshish and Cass and Leech Lakes. Water moves through the ground-water system predominantly horizontally in the aquifers, whereas vertical components of flow are significant in confining units. Downward leakage of water occurs in highland areas where ground water flows downward from overlying till to the uppermost confined aquifer. Water moves vertically upward from deep to shallow aquifers in areas of regional discharge, the Mississippi River, Cass Lake, Lake Winnibigoshish. and Leech Lake. Waters from both the unconfined and uppermost confined aquifers generally are suitable for domestic consumption, crop irrigation, and most other uses. Concentrations of iron and manganese in water from both aquifers frequently exceed levels that may impart an undesirable taste or odor to water. Calcium and bicarbonate are the predominant ions in water from both the unconfined and uppermost confined aquifers. Water from both the unconfined and uppermost confined aquifers is hard to very hard, averaging 187 and 247 milligrams per liter as calcium carbonate, respectively. Differences in the mean concentrations of constituents in waters from the unconfined and uppermost confined aquifers vary. The mean concentrations of chloride, manganese, dissolved organic carbon, sulfate, and dissolved iron were greater for water from the unconfined aquifer than for water from the uppermost confined aquifer. Conversely, the mean concentrations of calcium, potassium, silica, sodium, fluoride, and boron were greater for water from the uppermost confined aquifer than for water from the unconfined aquifer. These higher concentrations of naturally occurring constituents in waters from the uppermost confined aquifer may occur because of the longer flow paths and longer residence times of water in the uppermost confined aquifer as compared to the unconfined aquifer. Nutrients include nitrogen and phosphorus species. The mean concentrations of dissolved nitrogen (NO 2 + NO 3 , dissolved) and total phosphorus were about 5 and 1.5 times greater for water from the unconfined aquifer than for water from the uppermost confined aquifer, respectively. None of the water samples had concentrations of dissolved nitrogen greater than the maximum contaminant level established by the U.S. Environmental Protection Agency (10 milligrams per liter) and only one water sample had a concentration greater than 3 milligrams per liter. Water collected from wells completed in the unconfined aquifer in residential and recreational land-use areas had concentrations of arsenic, cadmium, chromium, copper, lead, mercury, and cyanide equal to or less than 6 micrograms per liter. Concentrations of organic-acid herbicides in water from three wells screened in the unconfined aquifer in managed-forest land-use areas were all below detection levels. Concentrations of U.S. Environmental Protection Agency priority pollutants in water from three wells screened in the unconfined aquifer and from one well screened in the uppermost confined aquifer were also all below detection levels.

Minnesota↗
USGS1995

Contamination of wells completed in the Roubidoux aquifer by abandoned zinc and lead mines, Ottawa County, Oklahoma

The Roubidoux aquifer in Ottawa County Oklahoma is used extensively as a source of water for public supplies, commerce, industry, and rural water districts. Water in the Roubidoux aquifer in eastern Ottawa County has relatively low dissolved-solids concentrations (less than 200 mg/L) with calcium, magnesium, and bicarbonate as the major ions. The Boone Formation is stratigraphically above the Roubidoux aquifer and is the host rock for zinc and lead sulfide ores, with the richest deposits located in the vicinity of the City of Picher. Mining in what became known as the Picher mining district began in the early 1900's and continued until about 1970. The water in the abandoned zinc and lead mines contains high concentrations of calcium, magnesium, bicarbonate, sulfate, fluoride, cadmium, copper, iron, lead, manganese, nickel, and zinc. Water from the abandoned mines is a potential source of contamination to the Roubidoux aquifer and to wells completed in the Roubidoux aquifer. Water samples were collected from wells completed in the Roubidoux aquifer in the Picher mining district and from wells outside the mining district to determine if 10 public supply wells in the mining district are contaminated. The chemical analyses indicate that at least 7 of the 10 public supply wells in the Picher mining district are contaminated by mine water. Application of the Mann-Whitney test indicated that the concentrations of some chemical constituents that are indicators of mine-water contamination are different in water samples from wells in the mining area as compared to wells outside the mining area. Application of the Wilcoxon signed-rank test showed that the concentrations of some chemical constituents that are indicators of mine-water contamination were higher in current (1992-93) data than in historic (1981-83) data, except for pH, which was lower in current than in historic data. pH and sulfate, alkalinity, bicarbonate, magnesium, iron, and tritium concentrations consistently indicate that the Cardin, Commerce 1, Commerce 3, Picher 2, Picher 3, Picher 4, and Quapaw 2 wells are contaminated.

Oklahoma↗
USGS1996

Geohydrology and water quality of the unconsolidated deposits in Erie County, Pennsylvania

Water in unconsolidated deposits is used for the water supplies of homes, farms, municipalities, and industries in Erie County. The unconsolidated deposits cover most of the bedrock of Erie County. Thickness of the unconsolidated deposits ranged from 60 to 400 feet at 30 sites surveyed by seismic refraction and reflection methods. Water wells, mostly in the unconsolidated deposits, provide adequate domestic supplies. Wells in fractured bedrock can generally provide small domestic supplies; however, droughts can affect some of the domestic water wells. Ground-water withdrawals accounted for 10 million gallons per day of the water used in Erie County in 1984. Mean annual precipitation ranged from 42 to 47 inches per year in Erie County from 1961 through 1990; the southeastern region of the county generally receives more precipitation than the lake shore region to the north. Overland runoff to three segments of the French Creek watershed in the upland area ranged from about 13 to 19 in. per year and base flow ranged from 14 to about 18 in. per year from 1975 to 1992. Evapotranspiration ranged from about 13 to 16 in. per year for those segments. Beach and outwash deposits generally provide the largest supplies of water to wells in Erie County. A median specific capacity of 17 (gal/min)/ft (gallons per minute per foot) of drawdown was determined from records of nondomestic wells in beach deposits and 9 (gal/min)/ft of drawdown in outwash. Mean specific capacity for wells in till deposits was 1.5 (gal/min)/ft. The range in yield and specific capacity, however, was great for the unconsolidated deposits and high yielding outwash deposits are sometimes difficult to locate beneath till and valley-fill deposits. Hydraulic conductivities from three aquifer tests of outwash deposits (sand and gravel) at separate sites ranged from 110 to 2,030 ft/d (feet per day). Hydraulic conductivities from another aquifer test of sand and silt in the water table at Presque Isle ranged from 120 to 215 ft/d. Transmissivities from a third aquifer test of beach sand and gravel ranged from 235 to 262 feet squared per day. Laboratory analyses of stream samples collected during base flows in 1987 and 1988 indicate that concentrations of arsenic, barium, cadmium, chromium, fluoride, lead, mercury, and selenium did not exceed the maximum contaminant levels (MCL's) established for drinking water by the U.S. Environmental Protection Agency (USEPA). Concentrations of two nontoxic elements, iron and manganese, exceeded USEPA secondary maximum contaminant levels (SMCL's) in samples from selected stream sites. Manganese concentrations exceeded the SMCL of 0.05 milligrams per liter at 19 of 30 stream sites sampled in the Upland Plateau Section of Erie County. Twenty-one wells were sampled for inorganic constituents and selected pesticides. Some samples from three of the wells exceeded the MCL for nitrate. Total arsenic concentrations above the MCL of 50 micrograms per liter were documented intermittently in three water wells in North East Township. Water from six of seven tile drains sampled in agricultural fields contained detectable concentrations of herbicides. These samples document the transport of the herbicides from the shallow ground-water system to local streams. Herbicide concentrations were at or more than minimum reporting levels for atrazine, cyanazine, prometone, and simazine. Atrazine concentrations in all seven samples from tile drains did not exceed the USEPA MCL of 3.0 micrograms per liter.

Water-Resources Investigations Report↗
USGS1996

Soil, water, and streambed quality at a demolished asphalt plant, Fort Bragg, North Carolina, 1992-94

A number of potentially hazardous chemicals were used at an asphalt plant on the Fort Bragg U.S. Army Reservation near Fayetteville, North Carolina. This plant was demolished in the late 1960's. Samples collected from soil, ground water, surface water, and streambed sediment were tested for the presence of contaminants. The sediment immediately underlying the demolished asphalt plant site consists mainly of sands, silts, and clayey sands with interbedded clay occurring at various depths. About 12 inches of rainfall per year infiltrate the unconfined surficial aquifer. The water table in this area is about 233 to 243 feet above sea level. Local ground water moves laterally, mainly towards the north- to-northwest at a rate of about 35 feet per year. where it discharges to Tank Creek, Little River, or one of their tributaries. A series of confining clays separate the surficial aquifer from the underlying upper Cape Fear aquifer. These clays help retard vertical migration of constituents dissolved in ground water. The saprolite-bedrock aquifer lies below the upper Cape Fear aquifer. In general ground water in the seven monitoring wells screened in the upper and lower part of the surficial aquifer did not contain detectable concentrations of chemicals related to past asphalt-plant activities. A small number of chemicals that were assumed to be unrelated to the asphalt plant were present in some of the study area monitoring wells. Ground water in four wells contained concentrations of organochlorine pesticides. Of these pesticides, concentrations of gamma-benzene hexachloride (lindane) (maximum of 0.76 micrograms per liter) exceeded the U.S. Environmental Protection Agency maximum contaminant level of 0.2 micrograms per liter in two wells. In addition, one well contained a trichloroethane concentration (7.7 micrograms per liter) that is assumed to be unrelated to demolished asphalt-plant operations, but exceeded the U.S. Environmental Protection Agency maximum contaminant level of 5.0 micrograms per liter. One well contained a fluoride concentration of 5.2 milligrams per liter that exceeded the U.S. Environmental Protection Agency maximum contaminant level of 4.0 milligrams per liter. Total and dissolved metals concentrations were generally typical of background levels. Some of the wells contained elevated levels of chloride (maximum of 749 milligrams per liter), specific conductance (maximum of 2,780 microsiemens per centimeter at 25 degrees Celsius), and dissolved solids (maximum of 1,520 milligrams per liter). Twelve of twenty-two soil samples that were collected at various depths at monitoring-well locations did not contain volatile organic compounds or polynuclear aromatic hydrocarbons. The remaining ten soil samples contained very low concentrations of polynuclear aromatic hydrocarbons and (or) analytical laboratory-related volatile organic compounds. The maximum concentrations were for fluoranthene and pyrene, at 780 and 750 micrograms per kilogram, respectively. In general, the polynuclear aromatic hydrocarbon concentrations were in sediment near the land surface. Streambed sediment from an unnamed, eastern tributary to Tank Creek in the eastern part of the site contained a small number of organochlorine pesticide compounds (a maximum of 1,400 milligrams per kilogram of 4,4'-DDD) and total petroleum hydrocarbons (113 milligrams per kilogram). Concentrations of metals and other inorganic constituents were generally typical of background concentrations. Surface water in this tributary did not contain elevated concentrations of anthropogenic chemicals.

North Carolina↗
USGS1996

Hydrogeology and ground-water quality of the chromic acid pit site, U.S. Army Air Defense Artillery Center and Fort Bliss, El Paso, Texas

The Chromic Acid Pit site is an inactive waste disposal site that is regulated by the Resource Conservation and Recovery Act of 1976. The 2.2-cubic-yard cement-lined pit was operated from 1980 to 1983 by a contractor to the U.S. Army Air Defense Artillery Center and Fort Bliss. The pit, located on the Fort Bliss military reservation, in El Paso, Texas, was used for disposal and evaporation of chromic acid waste generated from chrome plating operations. The site was certified closed in 1989 and the Texas Natural Resources Conservation Commission issued Permit Number HW-50296 (U.S. Environmental Protection Agency Permit Number TX4213720101), which approved and implemented post-closure care for the Chromic Acid Pit site. In accordance with an approved post-closure plan, the U.S. Geological Survey is cooperating with the U.S. Army in evaluating hydrogeologic conditions and ground- water quality at the site. One upgradient and two downgradient ground-water monitoring wells were installed adjacent to the chromic acid pit by a private contractor. Quarterly ground-water sampling of these wells by the U.S. Geological Survey began in December 1993. The Chromic Acid Pit site is situated in the Hueco Bolson intermontane valley. The Hueco Bolson is a primary source of ground water in the El Paso area. City of El Paso and U.S. Army water-supply wells are located on all sides of the study area and are completed 600 to more than 1,200 feet below land surface. The ground-water level in the area of the Chromic Acid Pit site has declined about 25 feet from 1982 to 1993. Depth to water at the Chromic Acid Pit site in September 1994 was about 284 feet below land surface; ground-water flow is to the southeast. Ground-water samples collected from monitoring wells at the Chromic Acid Pit site contained dissolved-solids concentrations of 442 to 564 milligrams per liter. Nitrate as nitrogen concentrations ranged from 2.1 to 2.7 milligrams per liter; nitrite plus nitrate as nitrogen concentrations ranged from 2.3 to 3.0 milligrams per liter. Nitrate concentrations are abnormally high in the Old Mesa well field located about 5,000 feet southwest of the Chromic Acid Pit site. Volatile and semivolatile organic compounds in water samples were analyzed for the first sampling round; no confirmed volatile or semivolatile organic compounds were detected above the laboratory reporting limits. Total chromium concentrations ranged from 0.0099 to 0.092 milligram per liter; dissolved chromium concentrations ranged from 0.0068 to 0.0094 milligram per liter. Overall, water-quality characteristics in water from the chromic acid pit ground-water monitoring wells are similar to those in the surrounding area. Detected chemical concentrations in water from the chromic acid pit monitoring wells during the four sampling periods were below U.S. Environmental Protection Agency-established maximum contaminant levels for public drinking water supplies. Statistical analyses were performed on 39 of the chemical constituents analyzed for in ground water from the chromic acid pit monitoring wells. Concentrations of chloride and fluoride were significantly less in water from the downgradient wells than in water from the upgradient well, whereas concentrations of nitrate as nitrogen, nitrite plus nitrate as nitrogen, and dissolved solids were significantly greater in water from the downgradient wells than in water from the upgradient well. Concentrations of nitrate as nitrogen were significantly different in water from the two downgradient wells. Differences detected through statistical analysis of chemical constituents of water in the chromic acid pit monitoring wells did not appear to indicate a release of hazardous chemicals from the chromic acid pit. There was no indication of ground-water contamination in either downgradient well.

Texas↗
USGS1996

Ground-water quality, water year 1995, and statistical analysis of ground-water-quality data, water years 1994-95, at the chromic acid pit site, U.S. Army Air Defense Artillery Center and Fort Bliss, El Paso, Texas

The Chromic Acid Pit site is an inactive waste disposal site that is regulated by the Resource Conservation and Recovery Act of 1976. The 2.2-cubic-yard cement-lined pit was operated from 1980 to 1983 by a contractor to the U.S. Army Air Defense Artillery Center and Fort Bliss. The pit, located on the Fort Bliss military reservation in El Paso, Texas, was used for disposal and evaporation of chromic acid waste generated from chrome plating operations. The site was closed in 1989, and the Texas Natural Resources Conservation Commission issued permit number HW-50296 (U.S. Environmental Protection Agency number TX4213720101), which approved and implemented post-closure care for the Chromic Acid Pit site. In accordance with an approved post-closure plan, the U.S. Geological Survey is cooperating with the U.S. Army in monitoring and evaluating ground-water quality at the site. One upgradient ground-water monitoring well (MW1) and two downgradient ground-water monitoring wells (MW2 and MW3), installed adjacent to the chromic acid pit, are monitored on a quarterly basis. Ground-water sampling of these wells by the U.S. Geological Survey began in December 1993. The ground-water level, measured in a production well located approximately 1,700 feet southeast of the Chromic Acid Pit site, has declined about 29.43 feet from 1982 to 1995. Depth to water at the Chromic Acid Pit site in September 1995 was 284.2 to 286.5 feet below land surface; ground-water flow at the water table is assumed to be toward the southeast. Ground-water samples collected from monitoring wells at the Chromic Acid Pit site during water year 1995 contained dissolved- solids concentrations of 481 to 516 milligrams per liter. Total chromium concentrations detected above the laboratory reporting limit ranged from 0.0061 to 0.030 milligram per liter; dissolved chromium concentrations ranged from 0.0040 to 0.010 milligram per liter. Nitrate as nitrogen concentrations ranged from 2.1 to 2.8 milligrams per liter; nitrite plus nitrate as nitrogen concentrations ranged from 2.4 to 3.2 milligrams per liter. Water samples from wells MW1 and MW2 were analyzed for volatile organic compounds for the first quarter; no confirmed volatile organic compounds were detected above laboratory reporting limits. Detected chemical concentrations in water from the chromic acid pit monitoring wells during the four sampling periods were below U.S. Environmental Protection Agency-established maximum contaminant levels for public drinking-water supplies. Overall, water-quality characteristics of water from the chromic acid pit ground-water monitoring wells are similar to those of other wells in the surrounding area. Statistical analyses were performed on 56 of the chemical constituents analyzed for in ground water from the chromic acid pit monitoring wells. Concentrations of chloride, fluoride, sulfate, and potassium were significantly less in water from one or both downgradient wells than in water from the upgradient well. Concentrations of nitrate as nitrogen, nitrite plus nitrate as nitrogen, and dissolved solids were significantly greater in water from the downgradient wells than in water from the upgradient well. Concentrations of nitrate as nitrogen, chloride, and potassium were significantly different in water from the two downgradient wells. Statistical analysis of chemical constituents in water from the chromic acid pit monitoring wells did not appear to indicate a release of hazardous chemicals from the chromic acid pit. There was no indication of ground-water contamination in either downgradient well.

Texas↗
USGS1997

Chlorofluorocarbon and tritium age determination of ground-water recharge in the Ryan Flat subbasin, Trans-Pecos Texas

A study was conducted to determine the relative influence of mountain-front infiltration in the Ryan Flat subbasin and to determine whether recent recharge (post-1940), which is of importance to water-use planning, has reached the Salt Basin aquifer, Trans-Pecos Texas. The alluvial and volcanic Salt Basin aquifer lies within a bolson, and the average depth to water in most of the subbasin is approximately 250 feet. Concentrations of the chlorofluorocarbons CFC-11, CFC-12, and CFC-113, as well as tritium, were measured in water from 10 wells in the study area. CFC-model recharge dates ranged from pre-1940 to the early 1970's. Ground water in five wells had CFC-model dates of pre-1940 or pre-1945. Ground water in two wells had dates of the mid- to late 1940's. Ground water from one well had a CFC-model recharge age of the early 1950's. Samples from the remaining two wells were most probably contaminated in some manner and are probably unreliable. CFC-model ages were calculated independently for the three chlorofluorocarbons, though the presence of volatile organic compounds affected agreement among them. Tritium activities in the nine wells for which tritium was analyzed indicated pre-1953 recharge and thus agreed approximately with the CFC-model dates. Ground water was analyzed for selected water-quality constituents. Water from all wells met U.S. Environmental Protection Agency national primary and secondary drinking water standards for all tested constituents except fluoride in samples from three wells. Silica concentrations in water from six wells exceeded a range considered typical in natural waters.

Water-Resources Investigations Report↗
USGS1998

Chemistry and isotopic composition of ground water along a section near the Newmark area, San Bernardino County, California

Chemical and isotopic analyses and flow-meter measurements in pumped wells were used to determine the source, movement, and age of ground water along a section of the valley-fill aquifer from the San Jacinto Fault to the base of the San Bernardino Mountains near the Newmark area in the Bunker Hill Basin of southern California. Water samples were collected from four multiple-depth well sites, from different depths within three production wells, and from two nearby streams; these samples were analyzed for major ions, selected trace elements, stable isotopes of oxygen and hydrogen (delta oxygen-18 and delta deuterium), tritium, and carbon-14. Within the production wells, variations in vertical flowrate with depth were recorded during pumped conditions using a standard spinner tool. Where saturated, the upper 200 feet of unconsolidated deposits contributed as much as 60 percent of the well discharge; deposits at depths greater than 700 feet contributed less than 10 percent. Chemical analyses indicate that three general zones of ground-water quality are present along a north-south section--an oxygenated zone near the base of the San Bernardino Mountains, an oxygen-depleted zone near the San Jacinto Fault, and a deeper zone characterized by concentrations of fluoride greater than 1 mg/L and by a general water-quality composition similar to that of base flow in East Twin Creek. The presence of tritium in water from wells along the section indicates that post-1952 recharge has moved rapidly through the valley-fill aquifer to depths as great as 800 feet. Carbon-14 data indicate that the maximum age of ground water, sampled at depths ranging from 600 to 1,000 feet, is less than 5,000 years before present. Ground water along the study section is much younger than ground water from similar depths in other nearby basins. Delta oxygen-18 and delta deuterium data indicate that as much as 25 percent of the discharge from some wells near the base of the San Bernardino Mountains is water that was imported from northern California. Improved knowledge of depth-dependent ground-water flow along this section can aid in the design of an effective strategy for basin management, including remediation of the Newmark area, which is designated by the U.S. Environmental Protection Agency as a Superfund cleanup site.

Water-Resources Investigations Report↗