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At least 55 records · Page 3Linked to original sources
USGS1987

Relation of water chemistry of the Edwards aquifer to hydrogeology and land use, San Antonio Region, Texas

Water-chemistry data from the Edwards aquifer for 1976-85, consisting of nearly 1,500 chemical analyses from 280 wells and 3 springs, were used to statistically evaluate relations among ground-water chemistry, hydrogeology, and land use. Five land uses associated with sampled wells were classified on the basis of published information and field surveys. Four major subareas of the aquifer were defined to reflect the relative susceptibility of ground water to contamination originating from human activities using hydrogeologic and tritium data. Water from an agricultural area over the unconfined zone of the aquifer had the largest median concentration of nitrite plus nitrate. Large nitrite plus nitrate concentrations were spatially associated with large tritium concentrations and nitrogen isotopic ratios characteristic of streamflow recharge. Detections of fecal-coliform bacteria were associated mainly with water from wells completed in the unconfined zone. Most of the occurrences of tetrachloroethylene, l,2-(trans)-dichloroethylene, trichlorofluoromethane, 1,1,1-trichloroethane, and 2,4-D in ground water were associated with wells completed in the unconfined zone of the aquifer. Fatty acids detected in water from some wells may commonly be present naturally in ground water. The percentage of samples in which arsenic, barium, lead, and zinc were detected was similar among subareas; the samples were from the freshwater parts of the aquifer. Large lead and zinc concentrations were associated with volumes of pumpage less than 1,000 gallons. In general, the quality of ground water in the freshwater parts of the aquifer (north of the "bad-water" line) is suitable for all uses including human consumption. Two areas that are exceptions are: (1) Northeast of Garner Field in Uvalde, Texas, where PCE (tetrachloroethylene) has been detected in groundwater samples, and (2) north-central Bexar County near the former West Avenue landfill where PCE and benzene have been detected in ground-water samples. Concentrations of these organic compounds in water from many wells in the two areas exceed the maximum contaminant level for human consumption set by the U.S. Environmental Protection Agency.

Water-Resources Investigations Report↗
USGS1995

The association of water chemistry variables and fish condition in streams of Shenandoah National Park (USA)

As part of the “Shenandoah National Park: Fish in Sensitive Habitats” (SNP:FISH) project, the blacknose dace ( Rhinichthys atratulus ) was utilized as an indicator species to assess the susceptibility of the ichthyofaunal community of Shenandoah National Park (USA) to acidification. Water chemistry (ANC, conductivity, pH, and concentrations of Ca 2+ , Mg 2+ , Na + , K + , Cl − , NO 3 − , SO 4 2− , and SiO 2 ) was sampled every three months over the course of 3 1/4 years which represents the probable maximum lifetime of R atratulus. Condition factors (K=[g/mm 3 ] * 10 6 ) were calculated for samples of fish (age class 2+ yr; n=370) from nine montane, second/third order streams representing a range of ANCs. A principle components regression was performed on factor scores from a principle components analysis of the water chemistry variables and fish condition factor. Two factors, one associated with stream water ANC and ion concentrations, and another associated with SO 4 2− concentration, collectively explained 84% of the variance in condition factor. The influence of variables other than water chemistry upon R atratulus K is addressed. The results show that environmental chemistry is highly associated with the K of R atratulus.

Shenandoah National Park↗
USGS1997

Geohydrology and water chemistry in the Rialto-Colton Basin, San Bernardino County, California

The 40-square-mile Rialto-Colton ground- water basin is in western San Bernardino County, California, about 60 miles east of Los Angeles.This basin was chosen for storage of imported water because of the good quality of native ground water, the known capacity for additional ground-water storage in the basin, and the availability of imported water. Because the movement and mixing of imported water needed to be determined, the San Bernardino Valley Municipal Water District entered into a cooperative program with the U.S.Geological Survey in 1991 to study the geohydrology and water chemistry in the Rialto- Colton basin. Ground-water flow and chemistry were investigated using existing data, borehole- geophysical and lithologic logs from newly drilled test holes, measurement of water levels, and chemical analyses of water samples. The Rialto-Colton basin is bounded on the northwest and southeast by the San Gabriel Mountains and the Badlands, respectively. The San Jacinto Fault and Barrier E form the northeastern boundary, and the Rialto-Colton Fault forms the southwestern boundary. Except in the southeastern part of the basin, the San Jacinto and Rialto-Colton Faults act as groundwater barriers that impede ground- water flow into and out of the basin.Barrier E generally does not impede ground- water flow into the basin. The ground-water system consists primarily of gravel, sand, silt, and clay. The maximum thickness is greater than 1,000 feet. The ground- water system is divided into four water-bearing units: river-channel deposits, and upper, middle, and lower water-bearing units. Relatively impermeable consolidated deposits underlie the lower water- bearing unit and form the lower boundary of the ground- water system. Ground water moves from east to west in the river-channel deposits and upper water-bearing unit in the southeastern part of the basin, and from northwest to southeast in the middle and lower water-bearing units. Two major internal faults, Barrier J and an unnamed fault, affect ground-water movement. Ground water moves across Barrier J in the unfaulted part of the ground-water system. The unnamed fault is a partial barrier to ground-water movement in the middle water- bearing unit and an effective barrier in the lower water-bearing unit.Imported water flows laterally across the unnamed fault above the saturated zone. Major sources of recharge to the ground- water system are underflow; precipitation that collects in small streams that drain the San Gabriel Mountains and the Badlands or runs off the mountain front as sheet flow, and sub-surface inflow; imported water; seepage loss from the Santa Ana River and Warm Creek; infiltration of rainfall; and irrigation return flow. The main component of discharge is pumpage. Long-term water levels in production wells reflect precipitation cycles. During a 194777 dry period, water levels in three wells declined almost continuously?as much as 100 feet in one well.Water levels in a well north of Barrier J are not affected by stresses on the groundwater system south of the barrier, indicating that these two parts of the ground-water system are not well connected. Water levels in cluster wells east of the unnamed fault north and south of the Linden Ponds artificial-recharge site rose as much as 70 feet during 1992-95. The rise in water levels in wells near the recharge ponds was observed within 2 months after the beginning of recharge. Water levels in most wells west of the unnamed fault changed very little during 1992-95. Water-chemistry data indicate that chemical characteristics vary within the groundwater system, and that dissolvedsolids concentrations are generally higher in the river-channel deposits, upper water- bearing unit, and the consolidated deposits than in the middle and lower water-bearing units. The chemical characteristics in water from the middle water-bearing unit were similar for most wells sampled west of the unnamed fault. In water from well

Water-Resources Investigations Report↗
USGS1995

Geology, Streamflow, and Water Chemistry of the Talufofo Stream Basin, Saipan, Northern Mariana Islands

A study of the geology, streamflow, and water chemistry of Talufofo Stream Basin, Saipan, Commonwealth of the Northern Mariana Islands, was undertaken to determine the flow characteristics of Talufofo Stream and the relation to the geology of the drainage basin. The Commonwealth government is exploring the feasibility of using water from Talufofo Stream to supplement Saipan's stressed municipal water supply. Streamflow records from gaging stations on the principal forks of Talufofo Stream indicate that peak streamflows and long-term average flow are higher at the South Fork gaging station than at the Middle Fork gaging station because the drainage area of the South Fork gaging station is larger, but persistent base flow from ground-water discharge during dry weather is greater in the Middle Fork gaging station. The sum of the average flows at the Middle Fork and South Fork gaging stations, plus an estimate of the average flow at a point in the lower reaches of the North Fork, is about 2.96 cubic feet per second or 1.91 million gallons per day. Although this average represents the theoretical maximum long-term draft rate possible from the Talufofo Stream Basin if an adequate reservoir can be built, the actual amount of surface water available will be less because of evaporation, leaks, induced infiltration, and reservoir-design constraints. Base-flow characteristics, such as stream seepage and spring discharge, are related to geology of the basin. Base flow in the Talufofo Stream Basin originates as discharge from springs near the base of limestones located in the headwaters of Talufofo Stream, flows over low-permeability volcanic rocks in the middle reaches, and seeps back into the high-permeability limestones in the lower reaches. Water sampled from Talufofo Stream during base flow had high dissolved-calcium concentrations (between 35 and 98 milligrams per liter), characteristic of water from a limestone aquifer. Concentrations of potassium, sodium, and chloride ions in water samples from Talufofo Stream are characteristic of water draining a heavily vegetated basin near the ocean. The streamflow and water-chemistry data indicate that discharge from springs is in hydraulic connection with the limestone aquifer near the headwaters of the basin. The base flow therefore is subject to stresses placed on the nearby limestone ground-water system. Pumping from wells in the limestones at the headwaters of Talufofo Stream Basin may decrease spring flow in Talufofo Stream.

Water-Resources Investigations Report↗
USGS2001

Vertical gradients in water chemistry in the central High Plains aquifer, southwestern Kansas and Oklahoma panhandle, 1999

The central High Plains aquifer is the primary source of water for domestic, industrial, and irrigation uses in parts of Colorado, Kansas, New Mexico, Oklahoma, and Texas. Water-level declines of more than 100 feet in some areas of the aquifer have increased the demand for water deeper in the aquifer. The maximum saturated thickness of the aquifer ranged from 500 to 600 feet in 1999. As the demand for deeper water increases, it becomes increasingly important for resource managers to understand how the quality of water in the aquifer changes with depth. In 1998?99, 18 monitoring wells at nine sites in southwestern Kansas and the Oklahoma Panhandle were completed at various depths in the central High Plains aquifer, and one monitoring well was completed in sediments of Permian age underlying the aquifer. Water samples were collected once from each well in 1999 to measure vertical gradients in water chemistry in the aquifer. Tritium concentrations measured in ground water indicate that water samples collected in the upper 30 feet of the aquifer were generally recharged within the last 50 years, whereas all of the water samples collected at depths more than 30 feet below the water table were recharged more than 50 years ago. Dissolved oxygen was present throughout the aquifer, with concentrations ranging from 1.7 to 8.4 mg/L. Water in the central High Plains aquifer was predominantly a calcium-bicarbonate type that exhibited little variability in concentrations of dissolved solids with depth (290 to 642 mg/L). Exceptions occurred in some areas where there had been upward movement of mineralized water from underlying sediments of Permian age and areas where there had been downward movement of mineralized Arkansas River water to the aquifer. Calcium-sulfate and sodium-chloride waters dominated and concentrations of dissolved solids were elevated (862 to 4,030 mg/L) near the base of the aquifer in the areas of upward leakage. Dissolution of gypsum or anhydrite and halite in sediments of Permian age by ground water was the likely source of calcium, sulfate, sodium, and chloride in those waters. Calcium-sodium-sulfate waters dominated, and concentrations of dissolved solids were as large as 4,916 mg/L near the water table in the area of downward leakage. Dissolution of minerals in sedimentary deposits of marine origin in upstream areas of the Arkansas River drainage were the likely sources of calcium, sodium, and sulfate in those waters. Nitrate was detected throughout the aquifer and the background concentration was estimated to be 2.45 mg/L as N. The largest nitrate concentrations (8.28, 22, and 54.4 mg/L as N) occurred in recently recharged water collected adjacent to irrigated fields. Three pesticides (atrazine, metolachlor, simazine) and five pesticide degradation products (alachlor ethanesulfonic acid, alachlor oxanilic acid, deethylatrazine, metolachlor ethanesulfonic acid, metolachlor oxanilic acid) were detected in recently recharged water from six water-table wells. Five of the six wells were adjacent to irrigated fields. These data indicate that concentrations of nitrate and pesticides increased over time in some areas of the aquifer as a result of agricultural activities. Results from this study indicate that vertical gradients in water chemistry existed in the central High Plains aquifer. The chemical gradients resulted from chemical inputs to the aquifer from underlying sediments of Permian age, from the Arkansas River, and from agricultural activities. In areas where those chemical inputs occurred, water quality in the aquifer was impaired and may not have been suitable for some intended uses.

Water-Resources Investigations Report↗
USGS1978

Correction of ground-water chemistry and carbon isotopic composition for effects of CO2 outgassing

Direct P co 2 "> P co2 measurements on water samples from several CO 2 -charged warm springs are significantly higher than P co 2 "> P co2 values calculated from field pH and alkalinity (and other constituents). In addition, calcite saturation indices calculated from field pH and solution composition indicated supersaturation in samples which, on the basis of hydrogeologic concepts, should be near saturation or undersaturated. We attribute these discrepancies to uncertainties in field pH, resulting from CO 2 outgassing during pH measurement. Because samples for direct P co 2 "> P co2 measurement can be taken with minimal disturbance to the water chemistry, we have used the measured P co 2 "> P co2 to back calculate an estimate of the field pH and the carbon isotopic composition of the water before outgassing. By reconstructing water chemistry in this way, we find generally consistent grouping of δ 13 C "> δ 13 C , pH, and degree of calcite saturation in samples taken from the same source at different times, an observation which we expect based on our understanding of the hydrogeology and geochemistry of the ground-water systems. This suggests that for very careful geochemical work, particularly on ground-waters much above ambient temperature, P co 2 "> P co2 measurements may provide more information on the system and a better estimate of its state of saturation with respect to carbonate minerals than can field measurements of pH.

Geochimica et Cosmochimica Acta↗
USGS2002

Ground-water, surface-water, and water-chemistry data, Black Mesa Area, northeastern Arizona — 2000–2001, and performance and sensitivity of the 1988 USGS numerical model of the N aquifer

The N aquifer is the major source of water in the 5,400-square-mile area of Black Mesa in northeastern Arizona. Availability of water is an important issue in this area because of continued industrial and municipal use, a growing population, and precipitation of about 6 to 14 inches per year. The monitoring program in Black Mesa has been operating since 1971 and is designed to determine the long-term effects of ground-water withdrawals from the N aquifer for industrial and municipal uses. The monitoring program includes measurements of (1) ground-water pumping, (2) ground-water levels, (3) spring discharge, (4) surface-water discharge, and (5) ground-water chemistry. In 2000, total ground-water withdrawals were 7,740 acre-feet, industrial use was 4,490 acre-feet, and municipal use was 3,250 acre-feet. From 1999 to 2000, total withdrawals increased by 9 percent, industrial use increased by 7 percent, and municipal use increased by 12 percent. From 1999 to 2001, water levels declined in 10 of 15 wells in the unconfined part of the aquifer, and the median change was -0.4 foot. Water levels declined in 8 of 16 wells in the confined part of the aquifer, and the median change was -0.2 foot. From the prestress period (prior to 1965) to 2001, the median water-level change for 33 wells was -17.2 feet. Median water-level changes were -1.2 feet for 15 wells in the unconfined part of the aquifer and -31.0 feet for 18 wells in the confined part. Discharges were measured once in 1999 and once in 2001 at four springs. Discharges decreased by 5 percent and 33 percent at two springs and increased by 3 percent and 81 percent at two springs. For about the past 10 years, discharges did not significantly change in Burro Spring, the unnamed spring near Dennehotso, and Moenkopi School Spring. The record of discharge from a consistent measuring point for Pasture Canyon Spring is too short for statistical analysis of trends. Continuous records of surface-water discharge have been collected from July 1976 to 2000 at Moenkopi Wash, July 1996 to 2000 at Laguna Creek, June 1993 to 2000 at Dinnebito Wash, and April 1994 to 2000 at Polacca Wash. Median flows for November, December, January, and February of each water year were used as an index of ground-water discharge to those streams. There is no significant trend in the median winter flows for Moenkopi Wash from 1977 to 2000. The records for the other three streams are too short for a statistical analysis of trends. The median winter flows for Dinnebito Wash and Polacca Wash, however, appear to have decreased during the last 6 years. There is no apparent trend in the median winter flows for Laguna Creek since 1997. In 2001, water samples were collected from 12 wells and 4 springs and analyzed for selected chemical constituents. Dissolved-solids concentrations ranged from 102 to 628 milligrams per liter. Water samples from 9 of the wells and from the 4 springs had less than 350 milligrams per liter of dissolved solids. Water-chemistry data with sufficient years of record for a statistical analysis of trends over time are available from 7 wells and 4 springs. From about the mid-1980s or early 1990s to 2001 there are no significant trends in the concentrations of dissolved solids, chloride, and sulfate in water samples from 6 of the 7 wells. The concentration of one tested constituent (dissolved solids) in samples from Rocky Ridge PM3 significantly increased from 1990 to 2001. From the late 1980s to 2001, there are no significant trends in the concentrations of dissolved solids, chloride, and sulfate in water samples from Burro Spring, the unnamed spring near Dennehotso, and Pasture Canyon Spring. From 1987 to 2001, concentrations of chloride and sulfate significantly increased in water samples from Moenkopi School Spring and concentrations of dissolved solids did not significantly change. The performance and sensitivity of the 1988 USGS numerical model of the N aquifer were analyzed. The overall performance of the model in steady-state conditions is reasonable for residuals of heads (difference between observed and simulated steady-state heads); 80 percent of the absolute values of residuals are less than 38 feet. Simulated flows are about 40 percent different than estimated flows at two of three discharge areas; however, this comparison is only a rough approximation of performance because the accuracy of the estimated steady-state flows is uncertain. The overall performance of the model for transient conditions is fair for residuals of changes in head (difference between observed and simulated changes in head from steady state to 1999); 80 percent of the absolute values of residuals are less than 31 feet. The model is biased in two areas. In the Tuba City area, simulated changes in head are more negative than observed changes in head; all six residuals are positive, and three residuals are between 75 and 155 feet. In the confined area of the aquifer, observed changes in head are more negative than simulated changes in head; 12 of the 17 residuals are negative, and 8 residuals are between -57 and -20 feet. Analysis of model sensitivity indicates that recharge, transmissivity, and storage coefficient are the most important parameters for estimating heads, changes in heads, and flows. A strong correlation between recharge and transmissivity and a lack of independent and reliable estimates of recharge, transmissivity, and discharge create a uniqueness problem in model calibration. Several models could be constructed and calibrated with different values of recharge or transmissivity and still have similar fits to the observed data. Information from recent data and studies and more advanced modeling techniques could be used to develop a more representative and less uncertain model. Future data collection and studies should focus on obtaining a better definition of recharge, discharge, transmissivity, and storage coefficient.

Arizona↗
USGS2004

Vertical gradients in water chemistry and age in the southern High Plains Aquifer, Texas, 2002

The southern High Plains aquifer is the primary source of water used for domestic, industrial, and irrigation purposes in parts of New Mexico and Texas. Despite the aquifer's importance to the overall economy of the southern High Plains, fundamental ground-water characteristics, such as vertical gradients in water chemistry and age, remain poorly defined. As part of the U.S. Geological Survey's National Water-Quality Assessment Program, water samples from nested, short-screen monitoring wells installed in the southern High Plains aquifer at two locations (Castro and Hale Counties, Texas) were analyzed for field parameters, major ions, nutrients, trace elements, dissolved organic carbon, pesticides, stable and radioactive isotopes, and dissolved gases to evaluate vertical gradients in water chemistry and age in the aquifer. Tritium measurements indicate that recent (post-1953) recharge was present near the water table and that deeper water was recharged before 1953. Concentrations of dissolved oxygen were largest (2.6 to 5.6 milligrams per liter) at the water table and decreased with depth below the water table. The smallest concentrations were less than 0.5 milligram per liter. The largest major-ion concentrations generally were detected at the water table because of the effects of overlying agricultural activities, as indicated by postbomb tritium concentrations and elevated nitrate and pesticide concentrations at the water table. Below the zone of agricultural influence, major-ion concentrations exhibited small increases with depth and distance along flow paths because of rock/water interactions and mixing with water from the underlying aquifer in rocks of Cretaceous age. The concentration increases primarily were accounted for by dissolved sodium, bicarbonate, chloride, and sulfate. Nitrite plus nitrate concentrations at the water table were 2.0 to 6.1 milligrams per liter as nitrogen, and concentrations substantially decreased with depth in the aquifer to a maximum concentration of 0.55 milligram per liter as nitrogen. Dissolved-gas and nitrogen-isotope data from the deep wells in Castro County indicate that denitrification occurred in the aquifer, removing 74 to more than 97 percent of the nitrate originally present in recharge. There was no evidence of denitrification in the deep part of the aquifer in Hale County. After correcting for denitrification effects, the background concentration of nitrate in water recharged before 1953 ranged from 0.4 to 3.2 milligrams per liter as nitrogen, with an average of 1.6 milligrams per liter as nitrogen. The d15N composition of background nitrate at the time of recharge was estimated to range from 9.6 to 12.3 per mil. Mass-balance models indicate that the decreases in dissolved oxygen and nitrate concentrations and small increases in major-ion concentrations along flow paths can be accounted for by small amounts of silicate-mineral and calcite dissolution; SiO2, goethite, and clay-mineral precipitation; organic-carbon and pyrite oxidation; denitrification; and cation exchange. Mass-balance models for some wells also required mixing with water from the underlying aquifer in rocks of Cretaceous age to achieve mole and isotope balances. Carbon mass transfers identified in the models were used to adjust radiocarbon ages of water samples recharged before 1953. Adjusted radiocarbon ages ranged from less than 1,000 to 9,000 carbon-14 years before present. Radiocarbon ages were more sensitive to uncertainties in the carbon-14 content of recharge than uncertainties in carbon mass transfers, leading to 1-sigma uncertainties of about ?2,000 years in the adjusted ages. Despite these relatively large uncertainties in adjusted radiocarbon ages, it appears that deep water in the aquifer was considerably older (at least 1,000 years) than water near the water table. There was essentially no change in ground-water age with depth in deeper parts of the aquifer, indicating that water in that

Texas↗
USGS2002

Ground-water, surface-water and water-chemistry data, Black Mesa area, northeastern Arizona: 2001-02

The N aquifer is the major source of water in the 5,400-square-mile area of Black Mesa in northeastern Arizona. Availability of water is an important issue in this area because of continued industrial and municipal use, a growing population, and precipitation of about 6 to 14 inches per year. The monitoring program in the Black Mesa area has been operating since 1971 and is designed to determine the long-term effects of ground-water withdrawals from the N aquifer for industrial and municipal uses. The monitoring program includes measurements of (1) ground-water pumping, (2) ground-water levels, (3) spring discharge, (4) surface-water discharge, and (5) ground-water chemistry. In 2001, total ground-water withdrawals were 7,680 acre-feet, industrial use was 4,530 acre-feet, and municipal use was 3,150 acre-feet. From 2000 to 2001, total withdrawals decreased by 1 percent, industrial use increased by 1 percent, and municipal use decreased by 3 percent. From 2001 to 2002, water levels declined in 5 of 14 wells in the unconfined part of the aquifer, and the median change was +0.2 foot. Water levels declined in 12 of 17 wells in the confined part of the aquifer, and the median change was -1.4 feet. From the prestress period (prior to 1965) to 2002, the median water-level change for 32 wells was -15.8 feet. Median water-level changes were -1.3 feet for 15 wells in the unconfined part of the aquifer and -31.7 feet for 17 wells in the confined part. Discharges were measured once in 2001 and once in 2002 at four springs. Discharges decreased by 26 percent and 66 percent at two springs, increased by 100 percent at one spring, and did not change at one spring. For the past 10 years, discharges from the four springs have fluctuated; however, an increasing or decreasing trend is not apparent. Continuous records of surface-water discharge have been collected from 1976 to 2001 at Moenkopi Wash, 1996 to 2001 at Laguna Creek, 1993 to 2001 at Dinnebito Wash, and 1994 to 2001 at Polacca Wash. Median flows for November, December, January, and February of each water year were used as an index of ground-water discharge to those streams. Since 1995, the median winter flows have decreased for Moenkopi Wash, Dinnebito Wash, and Polacca Wash. Since 1997, there is no consistent trend in the median winter flow for Laguna Creek. In 2002, water samples were collected from 12 wells and 4 springs and analyzed for selected chemical constituents. Dissolved-solids concentrations ranged from 96 to 636 milligrams per liter. Water samples from 8 of the wells and from 3 of the springs had less than 300 milligrams per liter of dissolved solids. There are no appreciable time trends in the chemistry of water samples from 9 wells and 4 springs; the 9 wells had more than 7 years of data, and the 4 springs had more than 9 years of data.

Arizona↗
USGS2007

Ground-water, surface-water, and water-chemistry data, Black Mesa area, northeastern Arizona— 2005-06

The N aquifer is the major source of water in the 5,400 square-mile Black Mesa area in northeastern Arizona. Availability of water is an important issue in northeastern Arizona because of continued water requirements for industrial and municipal use and the needs of a growing population. Precipitation in the Black Mesa area averages about 6 to 14 inches per year. The water monitoring program in the Black Mesa area began in 1971 and is designed to provide information about the long-term effects of ground-water withdrawals from the N aquifer for industrial and municipal uses. This report presents results of data collected for the monitoring program in the Black Mesa area from January 2005 to September 2006. The monitoring program includes measurements of (1) ground-water pumping, (2) ground-water levels, (3) spring discharge, (4) surface-water discharge, (5) ground-water chemistry, and (6) periodic testing of ground-water withdrawal meters. In 2005, ground-water withdrawals in the Black Mesa area totaled 7,330 acre-feet, including ground-water withdrawals for industrial (4,480 acre-feet) and municipal (2,850 acre-feet) uses. From 2004 to 2005, total withdrawals increased by less than 2 percent, industrial withdrawals increased by approximately 3 percent, and total municipal withdrawals increased by 0.35 percent. From 2005 to 2006, annually measured water levels in the Black Mesa area declined in 10 of 13 wells in the unconfined areas of the N aquifer, and the median change was -0.5 foot. Measurements indicated that water levels declined in 12 of 15 wells in the confined area of the aquifer, and the median change was -1.4 feet. From the prestress period (prior to 1965) to 2006, the median water-level change for 29 wells was -8.5 feet. Median water-level changes were -0.2 foot for 13 wells in the unconfined areas and -46.6 feet for 16 wells in the confined area. Ground-water discharges were measured once in 2005 and once in 2006 at Moenkopi School Spring and Burro Spring. Discharge decreased by 3.5 percent at Moenkopi School Spring and by 15 percent at Burro Spring. During the period of record at each spring, discharges fluctuated; a decreasing trend was apparent. Continuous records of surface-water discharge in the Black Mesa area have been collected from streamflow gages at the following sites: Moenkopi Wash (1976 to 2005), Dinnebito Wash (1993 to 2005), Polacca Wash (1994 to 2005), Pasture Canyon Spring (August 2004 to December 2005), and Laguna Creek (1996 to 2005). Median flows during November, December, January, and February of each water year were used as an index of the amount of ground-water discharge to the above named sites. For the period of record at each streamflow-gaging station, the median winter flows have decreased for Moenkopi Wash, Dinnebito Wash, and Polacca Wash. There is not a long enough period of record for Pasture Canyon Spring and Laguna Creek was discontinued at the end of December 2005. In 2006, water samples were collected from 6 wells and 2 springs in the Black Mesa area and analyzed for selected chemical constituents. Dissolved-solids concentrations ranged from 111 to 588 milligrams per liter. Water samples from 5 of the wells and both of the springs had less than 500 milligrams per liter of dissolved solids. Trends in the chemistry of water samples from the 6 wells show the Pi?on NTUA 1 and Peabody 9 wells increasing in dissolved solids, Forest Lake NTUA 1 and Peabody 2 wells decreasing in dissolved solids, and Kykotsmovi PM2 and Keams Canyon PM2 wells show a steady trend. Increasing trends in dissolved-solids, chloride, and sulfate concentrations were evident from the more than 11 years of data for the 2 springs.

Arizona↗
USGS2005

Ground-water, surface-water, and water-chemistry data, Black Mesa area, northeastern Arizona — 2003–04

The N aquifer is the major source of water in the 5,400-square-mile area of Black Mesa in northeastern Arizona. Availability of water is an important issue in this area because of continued industrial and municipal use, a growing population, and precipitation of about 6 to 14 inches per year. The monitoring program in the Black Mesa area has been operating since 1971 and is designed to determine the long-term effects of ground-water withdrawals from the N aquifer for industrial and municipal uses. The monitoring program includes measurements of (1) ground-water pumping, (2) ground-water levels, (3) spring discharge, (4) surface-water discharge, (5) ground-water chemistry, and (6) periodic testing of ground-water withdrawal meters. In 2003, total ground-water withdrawals were 7,240 acre-feet, industrial withdrawals were 4,450 acre-feet, and municipal withdrawals were 2,790 acre-feet. From 2002 to 2003, total withdrawals decreased by 10 percent, industrial withdrawals decreased by 4 percent, and municipal withdrawals decreased by 20 percent. Flowmeter testing was completed for 24 municipal wells in 2004. The median difference between pumping rates for the permanent meter and a test meter for all the sites tested was -2.9 percent. Values ranged from -10.9 percent at Forest Lake NTUA 1 to +7.8 percent at Rough Rock NTUA 2. From 2003 to 2004, water levels declined in 6 of 12 wells in the unconfined part of the aquifer, and the median change was -0.1 foot. Water levels declined in 7 of 11 wells in the confined part of the aquifer, and the median change was -2.7 feet. From the prestress period (prior to 1965) to 2003, the median water-level change for 26 wells was -23.2 feet. Median water-level change were -6.1 feet for 14 wells in the unconfined parts of the aquifer and and -72.1 feet for 12 wells in the confined part. Discharges were measured once in 2003 and once in 2004 at four springs. Discharge stayed the same at Pasture Canyon Spring, increased 9 percent at Moenkopi Spring, decreased 26 percent at an unnamed spring near Dennehotso, and decreased 50 percent at Burro Spring. For the past 12 years, discharges from the four springs have fluctuated; however, an increasing or decreasing trend is not apparent. Continuous records of surface-water discharge have been collected from 1976 to 2003 at Moenkopi Wash, 1996 to 2003 at Laguna Creek, 1993 to 2003 at Dinnebito Wash, and 1994 to 2003 at Polacca Wash. Median flows for November, December, January, and February of each water year were used as an index of ground-water discharge to those streams. Since 1995, the median winter flows have decreased for Moenkopi Wash, Dinnebito Wash, and Polacca Wash. Since the first continuous record of surface-water discharge in 1997, there is no consistent trend in the median winter flow for Laguna Creek. In 2004, water samples were collected from 12 wells and 4 springs and analyzed for selected chemical constituents. Dissolved-solids concentrations ranged from 100 to 649 milligrams per liter. Water samples from 11 of the wells and from all the springs had less than 500 milligrams per liter of dissolved solids. There are no appreciable time trends in the chemistry of water samples from 7 wells and 2 springs; increasing trends in dissolved-solids and chloride concentrations were evident from the more than 10 years of data for 2 springs.

Arizona↗
USGS2004

Ground-water, surface-water, and water-chemistry data, Black Mesa area, northeastern Arizona — 2002-03

The N aquifer is the major source of water in the 5,400-square-mile area of Black Mesa in northeastern Arizona. Availability of water is an important issue in this area because of continued industrial and municipal use, a growing population, and precipitation of about 6 to 14 inches per year. The monitoring program in the Black Mesa area has been operating since 1971 and is designed to determine the long-term effects of ground-water withdrawals from the N aquifer for industrial and municipal uses. The monitoring program includes measurements of (1) ground-water pumping, (2) ground-water levels, (3) spring discharge, (4) surface-water discharge, (5) ground-water chemistry, and (6) periodic testing of ground-water withdrawal meters. In 2002, total ground-water withdrawals were 8,000 acre-feet, industrial use was 4,640 acre-feet, and municipal use was 3,360 acre-feet. From 2001 to 2002, total withdrawals increased by 4 percent, industrial use increased by 2 percent, and municipal use increased by 7 percent. Flowmeter testing was completed for 32 municipal wells in 2003. The median difference between pumping rates for the permanent meter and a test meter for all the sites tested was -2.0 percent. Values ranged from -13.7 percent at Hopi High School no. 2 to +12.9 percent at Shonto PM3. From 2002 to 2003, water levels declined in 5 of 13 wells in the unconfined part of the aquifer, and the median change was 0.0 foot. Water levels declined in 8 of 13 wells in the confined part of the aquifer, and the median change was -1.1 feet. From the prestress period (prior to 1965) to 2003, the median water-level change for 26 wells was -8.3 feet. Median water-level changes were -0.4 foot for 13 wells in the unconfirned part of the aquifer and -60.3 feet for 13 wells in the confined part. Discharges were measured once in 2002 and once in 2003 at four springs. Discharge decreased by 16 percent at Pasture Canyon Spring, increased 10 percent at Moenkopi Spring and 90 percent at an unnamed spring near Dennehotso, and did not change at Burro Spring. For the past 11 years, discharges from the four springs have fluctuated; however, an increasing or decreasing trend is not apparent. Continuous records of surface-water discharge have been collected from 1976 to 2002 at Moenkopi Wash, 1996 to 2002 at Laguna Creek, 1993 to 2002 at Dinnebito Wash, and 1994 to 2002 at Polacca Wash. Median flows for November, December, January, and February of each water year were used as an index of ground-water discharge to those streams. Since 1995, the median winter flows have decreased for Moenkopi Wash, Dinnebito Wash, and Polacca Wash. Since the first continuous record of surface-water discharge in 1997, there is no consistent trend in the median winter flow for Laguna Creek. In 2003, water samples were collected from 12 wells and 4 springs and analyzed for selected chemical constituents. Dissolved-solids concentrations ranged from 118 to 642 milligrams per liter. Water samples from 10 of the wells and from all of the springs had less than 500 milligrams per liter of dissolved solids. There are no appreciable time trends in the chemistry of water samples from 7 wells and 4 springs; 7 wells had more than 8 years of data, and the 4 springs had more than 10 years of data.

Arizona↗
USGS2006

Ground-water, surface-water, and water-chemistry data, Black Mesa area, northeastern Arizona — 2004–05

The N aquifer is the major source of water in the 5,400-square-mile area of Black Mesa in northeastern Arizona. Availability of water is an important issue in this area because of continued industrial and municipal use, a growing population, and precipitation of about 6 to 14 inches per year. The monitoring program in the Black Mesa area has been operating since 1971 and is designed to determine the long-term effects of ground-water withdrawals from the N aquifer for industrial and municipal uses. The monitoring program includes measurements of (1) ground-water pumping, (2) ground-water levels, (3) spring discharge, (4) surface-water discharge, (5) ground-water chemistry, and (6) periodic testing of ground-water withdrawal meters. In 2004, total ground-water withdrawals were 7,210 acre-feet, industrial withdrawals were 4,370 acre-feet, and municipal withdrawals were 2,840 acre-feet. From 2003 to 2004, total withdrawals decreased by less than 1 percent, industrial withdrawals decreased by 2 percent, and municipal withdrawals increased by 2 percent. From 2004 to 2005, annually measured water levels declined in 6 of 13 wells in the unconfined areas of the aquifer, and the median change was -0.1 foot. Water levels declined in 8 of 12 wells in the confined area of the aquifer, and the median change was -1.2 feet. From the prestress period (prior to 1965) to 2005, the median water-level change for 33 wells was -9.0 feet. Median water-level changes were -0.6 foot for 16 wells in the unconfined areas and -32.0 feet for 17 wells in the confined area. Discharges were measured once in 2004 and once in 2005 at four springs. Discharge increased by 8 percent at Pasture Canyon Spring, decreased by 5 percent at Moenkopi School Spring, increased by 71 percent at an unnamed spring near Dennehotso, and stayed the same at Burro Spring. For the period of record at each spring, discharges from the four springs have fluctuated; however, an increasing or decreasing trend is not apparent. Continuous records of surface-water discharge have been collected from 1976 to 2004 at Moenkopi Wash, 1996 to 2004 at Laguna Creek, 1993 to 2004 at Dinnebito Wash, 1994 to 2004 at Polacca Wash, and August 2004 to December 2004 at Pasture Canyon Spring. Median flows for November, December, January, and February of each water year were used as an index of ground-water discharge to those streams. Since 1995, the median winter flows have decreased for Moenkopi Wash, Dinnebito Wash, and Polacca Wash. Since the first continuous record of surface-water discharge in 1997, there is no consistent trend in the median winter flow for Laguna Creek. In 2005, water samples were collected from 11 wells and 4 springs and analyzed for selected chemical constituents. Dissolved-solids concentrations ranged from 122 to 639 milligrams per liter. Water samples from 9 of the wells and from all the springs had less than 500 milligrams per liter of dissolved solids. There are some long-term trends in the chemistry of water samples from 7 wells having more than 10 years of data and from 2 springs. Rough Rock PM5, Keams Canyon PM2, Second Mesa PM2, and Kayenta PM2 show an increasing trend in dissolved solids; Forest Lake NTUA1 and PWCC 2 show a decreasing trend in dissolved solids; and Kykostmovi PM2 shows a steady trend. Increasing trends in dissolved-solids and chloride concentrations were evident from the more than 11 years of data for 2 springs.

Arizona↗
USGS2021

A reactive transport approach to modeling cave seepage water chemistry II: Elemental signatures

Karst systems are useful for examining spatial and temporal variability in Critical Zone processes because they provide a window into the subsurface where waters have interacted with vegetation, soils, regolith, and bedrock across a range of length and timescales. These hydrologic pathways frequently include the precipitation of speleothems, which provide long-term archives of climate and environmental change. Trace element ratios in speleothems (Mg/Ca, Sr/Ca, Ba/Ca) have the potential to provide information about past changes in rainfall and infiltration, but controls on them can be complex and their interpretation must be based on an understanding of the modern cave system. Here we integrate observations of surface conditions, bedrock, soil, and drip water chemistry of Blue Spring Cave in Tennessee, USA with the reactive transport model CrunchTope, which we have calibrated for karst systems to investigate the primary controls on trace element variations in cave seepage waters. We find that measured drip water Mg/Ca and Sr/Ca are captured within the model through variable amounts of limestone dissolution followed by precipitation of secondary calcite that happens within the cave rather than the host limestone. However, strong spatial controls on drip water Mg/Ca and Sr/Ca likely reflect seepage water interactions with variable amounts of diagenetic phases in the host rock. In contrast, Ba/Ca values are consistent across the cave and vary with effective rainfall, suggesting that this parameter may be the most consistent metric for limestone dissolution and prior calcite precipitation and can act as a proxy for rainfall and infiltration in this cave system. Our findings emphasize the importance of evaluating spatial heterogeneity in cave drip waters and outline a novel modeling approach for determining the dominant controls on drip water chemistry in support of the interpretations of paleoclimate records.

Geochimica et Cosmochimica Acta↗
USGS2008

Environmental Monitoring and Assessment Program Western Pilot Project— Conditions of North Dakota perennial streams for water chemistry and mercury in fish tissue, 2000–2003

Sixty-five sampling sites, selected by a statistical design to represent lengths of perennial streams in North Dakota, were chosen to be sampled for water chemistry and mercury in fish tissue to establish unbiased baseline data. From the assessment of all water chemistry constituents, the percentage of stream length considered to be in poor condition was greater in the Rangeland Plains than in the Cultivated Plains. About 30 percent of perennial stream length in North Dakota was considered to be in good condition on the basis of mercury concentrations in fish tissue.

North Dakota↗
USGS2021

Groundwater, surface-water, and water-chemistry data, Black Mesa area, northeastern Arizona—2016–2018

The Navajo (N) aquifer is the primary source of groundwater in the 5,400-square-mile Black Mesa area in northeastern Arizona. Availability of water is an important issue in the Black Mesa area because of continued water requirements for industrial and municipal use by a growing population and because of its arid climate. Precipitation in the area typically ranges from less than 6 to more than 16 inches per year depending on location. The U.S. Geological Survey water-monitoring program in the Black Mesa area began in 1971 and provides information about the long-term effects of groundwater withdrawals from the N aquifer for industrial and municipal uses. This report presents results of data collected as part of the monitoring program in the Black Mesa area from November 2016 to December 2018. The monitoring program includes measurements of (1) groundwater withdrawals (pumping), (2) groundwater levels, (3) spring discharge, (4) surface-water discharge, and (5) groundwater and surface-water chemistry. In calendar year 2017, total groundwater withdrawals were 3,710 acre-feet (acre-ft), industrial withdrawals were 1,110 acre-ft, and municipal withdrawals were 2,600 acre-ft. In calendar year 2018, total groundwater withdrawals were 3,670 acre-ft, industrial withdrawals were 1,170 acre-ft, and municipal withdrawals were 2,500 acre-ft. Total withdrawals during 2017 and 2018 were about 49 percent less than total withdrawals in 2005 because of Peabody Western Coal Company’s discontinued use of water to transport coal in a coal slurry pipeline. From the prestress period (prior to 1965) to 2018, measured water levels available for comparison in wells completed in the unconfined areas of the N aquifer within the Black Mesa area declined in 8 of 14 wells, the changes ranged from +12.1 feet to −39.4 feet, and the median change was -0.6 feet. Water levels also declined in 15 of 18 wells measured in the confined area of the aquifer. The median change for the confined area of the aquifer was −40.2 feet (ft), with changes ranging from +14.2 ft to −189.0 ft. From the prestress period to 2018, the median water-level change for all 32 wells in both the confined and unconfined areas was −9.4 ft. Spring flow was measured at four springs in 2017 and 2018. Flow fluctuated during the period of record for Burro Spring and Pasture Canyon Spring, but a decreasing trend was statistically significant (p<0.05) at Moenkopi School Spring and Unnamed Spring near Dennehotso. Discharge at Burro Spring has remained relatively constant since it was first measured in the 1980s and discharge at Pasture Canyon Spring has fluctuated for the period of record. Continuous records of surface-water discharge in the Black Mesa area were collected from streamflow-gaging stations at the following sites: Moenkopi Wash at Moenkopi 09401260 (1976 to 2018), Dinnebito Wash near Sand Springs 09401110 (1993 to 2018), Polacca Wash near Second Mesa 09400568 (1994 to 2018), and Pasture Canyon Springs 09401265 (2004 to 2018). Median winter flows (November through February) of each water year were used as an index of the amount of groundwater discharge at the above-named sites. For the period of record, the median winter flows have generally remained constant at Dinnebito Wash and Polacca Wash, whereas a decreasing trend was indicated at Moenkopi Wash and Pasture Canyon Springs. In 2017 and 2018, water samples collected from two wells, four springs, and three streams in the Black Mesa area were analyzed for selected chemical constituents. The results from wells and springs were compared with previous analyses from the same wells and springs. At the Peabody 2 well, a significant (p<0.05) decreasing trend in dissolved solids over time was found, while concentrations of dissolved solids have not varied significantly (p>0.05) at the Kykotsmovi PM2 well. Dissolved solids, chloride, and sulfate concentrations increased at Moenkopi School Spring during the more than 30 years of record at that site. Concentrations of dissolved solids, chloride, and sulfate at Pasture Canyon Spring have not varied significantly (p>0.05) since the early 1980s, and there is no increasing or decreasing trend in those data. Concentrations of dissolved solids, chloride, and sulfate at Burro Spring and Unnamed Spring near Dennehotso have varied for the period of record, but there is no statistical trend in the data. Baseflow water chemistry samples were collected from Moenkopi, Dinnebito, and Polacca washes in 2017. Samples from all three washes had total-dissolved solids concentrations higher than is typically found in the N aquifer water.

Arizona↗
USGS1997

Effects of carbon dioxide variations in the unsaturated zone on water chemistry in a glacial-outwash aquifer

The research site at Otis Air Base, Cape Cod, Massachusetts, has been developed for hydrogeological and geochemical studies of sewage-effluent contaminated groundwater since 1982. Research of hydrologic properties, transport, and chemical and biological processes is ongoing, but the origin of background water chemistry has not been determined. The principal geochemical process giving rise to the observed background water chemistry is CO2-controlled hydrolysis of Na feldspar. Geochemical modeling demonstrated that CO2 sources could vary over the project area. Analyses of unsaturated zone gases showed variations in CO2 which were dependent on land use and vegetative cover in the area of groundwater recharge. Measurements of CO2 in unsaturated-zone gases showed that concentrations of total inorganic C in recharge water should range from about 0.035 to 1.0 mmoles/L in the vicinity of Otis Air Base. Flux of CO2 from the unsaturated zone varied for a principal land uses, ranging from 86 gC/m2/yr for low vegetated areas to 1630 gC/m2/yr for a golf course. Carbon dioxide flux from woodlands was 220 gC/m2/yr, lower than reported fluxes of 500 to 600 gC/m2/yr for woodlands in a similar climate. Carbon dioxide flux from grassy areas was 540 gC/m2/yr, higher than reported fluxes of 230 to 490 gC/m2/yr for grasslands in a similar climate.

Applied Geochemistry↗
USGS2011

Water chemistry and its effects on the physiology and survival of Atlantic salmon Salmo salar smolts

The physiological effects of episodic pH fluctuations on Atlantic salmon Salmo salar smolts in eastern Maine, U.S.A., were investigated. During this study, S. salar smolts were exposed to ambient stream‐water chemistry conditions at nine sites in four catchments for 3 and 6 day intervals during the spring S. salar smolt migration period. Plasma chloride, plasma glucose, gill aluminium and gill Na + ‐ and K + ‐ATPase levels in S. salar smolts were assessed in relation to ambient stream‐water chemistry during this migration period. Changes in both plasma chloride and plasma glucose levels of S. salar smolts were strongly correlated with stream pH, and S. salar smolt mortality occurred in one study site with ambient stream pH between 5·6 and 5·8 during the study period. The findings from this study suggest that physiological effects on S. salar smolts are strongly correlated with stream pH and that in rivers and streams with low dissolved organic carbon (DOC) concentrations the threshold for physiological effects and mortality probably occurs at a higher pH and shorter exposure period than in rivers with higher DOC. Additionally, whenever an acidification event in which pH drops below 5·9 coincides with S. salar smolt migration in eastern Maine rivers, there is potential for a significant reduction in plasma ions of S. salar smolts.

Maine↗