Groundwater conditions during 1990 and recent groundwater level and-quality trends in Georgia wer... more Groundwater conditions during 1990 and recent groundwater level and-quality trends in Georgia were evaluated using data from precipitation, groundwater level , and groundwater quality monitoring networks. Data for 1990 include precipitation records from 10 National Weather Service stations, continuous water-level records from 140 wells, periodic water-level measurements from an additional 1,227 wells, and chloride analyses from 176 wells. Annual mean groundwater levels in Qeorgia hi 1990 ranged from about 11.4 feet lower to about 3.2 feet higher than hi 1989. Of the 76 wells summarized hi this report, 24 had annual mean water levels that were higher than hi 1989. Record-high daily mean water levels were recorded in three wells tapping the Claiborne aquifer and two wells tapping crystalline-rock aquifers. These record highs were from about 0.4 to about 5.0 feet higher than previous record highs. The other 52 wells had annual mean water levels that were lower than hi 1989. Record-low daily mean water levels were recorded hi the Coastal Plain physiographic province hi two wells tapping surficial aquifers, one well tapping the upper Brunswick aquifer, 21 wells tapping the Floridan aquifer system, one well tapping the Claiborne aquifer, one well tapping the Clayton aquifer and seven wells tapping the Cretaceous aquifers and aquifer systems. These record lows were from slightly lower to about 7.8 feet lower than the previous record lows. Comparison of chloride-concentration maps for the Floridan aquifer system hi the coastal area indicates that chloride concentrations hi water from the Floridan aquifer system generally have changed little since 1988. In the coastal area, chloride concentrations hi water from the Upper Floridan aquifer that exceed U.S. Environmental Protection Agency and Georgia Department of Natural Resources, Environmental Protection Division, drinking-water standards have been detected only hi the Brunswick area. In the Brunswick area, changes hi chloride concentrations hi water from the Floridan aquifer system have been mixed. In the southern Brunswick area, chloride concentration hi water from the Lower Floridan aquifer has increased gradually since sampling began hi the late 1960's. In the northeastern Brunswick area, water hi two wells tapping the Upper Floridan aquifer showed trends of decreasing chloride concentrations that began in 1980 and 1984. In the northwestern Brunswick area, water hi two wells tapping the Upper Floridan aquifer showed trends of increasing chloride concentrations that have been present since sampling began hi 1970. In the Savannah area, chloride concentrations have shown little change since 1968, except for an increase hi three wells tapping deep zones of the Lower Floridan aquifer at the end of 1990. Monitoring groundwater levels and quality is essential to water-resources management. Groundwater levels and quality have been monitored in Georgia for about 100 years. In the early years, water-level data were used in areal reconnaissance studies to show water-level trends. These data had limited value for resource-management purposes because of the large period of tiflie between collection and publication of the data. As part of the cooperative groundwater investigations undertaken by the U.S. Geological Survey and the state of Georgia, a statewide water-level-measurement program was begun in 1938. Initially, this program consisted of an observation-well network hi the coastal area of Georgia that provided data concerning variations hi groundwater storage and quality. Additional wells were added water quality could forewarn potential water-resources prob in areas where variations in water levels and ems. During 1990, periodic water-level measurements were made in 1,227 wells, and 140 wells were monitored continuously. Continuous water-level records were obtained using analog (pen and chart) recorders, digital punch recorders that record water levels at 30-minute (min) or 60-min intervals, and data loggers that record water levels at 60-min intervals. At sites with missing record, data were estimated, where possible, using data from nearby wells that showed a similar water-level response to variations in precipitation and pumping. Water samples also were periodically collected and analyzed from 176 wells during 1990 to monitor chloride concentrations in the coastal area. Purpose and Scope Groundwater level and-quality data are an important part of groundwater assessment and management. Water-level data are used to indicate directions of groundwater flow and areas of recharge and discharge; indicate the change in aquifer storage as it is affected by distribution and rate of groundwater withdrawal; help define the hydraulic characteristics of aquifers; evaluate stream-aquifer relations; provide information for addressing water-management needs; and provide long-term records that can be used to evaluate the effects of management and conservation programs. This report continues a series of annual publications that present precipitation, groundwater level , and groundwater quality information for Georgia. Formerly titled "Ground-Water Data for Georgia", the title was changed to "Ground-Water Conditions in Georgia" in 1989 to more accurately reflect its content. Precipitation graphs for 10 National Weather Service stations, hydrographs for 76 wells, and water-level maps of the Upper Floridan, Claiborne, and Clayton aquifers are presented to illustrate the effects that variations in recharge and discharge have had on the various aquifers in the State. Chloride-Concentration graphs for 13 wells tapping the Floridan aquifer system in the coastal area, and chloride-concentration maps for the Upper Floridan aquifer in the coastal and Brunswick areas, have been included to show the distribution and variations in chloride concentration since monitoring began. PRECIPITATION Recharge to the groundwater system in Georgia is derived almost entirely from precipitation. Based on records for 1941-70, annual precipitation averaged 50 inches (in.) statewide, and ranged from 44 in. in the east-central part to about 76 in. in the northeastern corner (fig. 1) (Carter and Stiles, 1983). Of the total annual precipitation, about 88 percent is discharged to streams or is lost to evapotranspiration, and about 12 percent enters the groundwater system as recharge (Carter and Stiles, IS Monthly mean precipitation data furnished by the Administration (1990) are shown graphically for 10 precipitation stations (figs. 2-11). For each station, monthly precipitation was compared to the 30-year (yr) (1951-80) average (normal) for the station. Cumulative departure curves are a method often used to illustrate surplus U.S. National Oceanic and Atmospheric or deficit amounts of precipitation over a designated period of time. The curves used in this report were obtained by adding successive monthly values of precipitation departures from normal. For example, if precipitation in January was 2 in. above normal and in February was 1 in. below normal, the cumulative departure would be (+2) + (-l) = +1 in. Thus, the annual cumulative departure through December would represent the sum of all monthly deficits or surpluses during the year. Similarly, the 10-yr cumulative departure at the end of December would represent the sum of all monthly deficits or surpluses for the previous 119 months. For ;ach of the precipitation stations, the lower graph shows the cumulative departure from normal precipitation for the period 1981-90; the upper graph shows the monthly departure and cumulative departure for 1990. At the end of the year, the cumulative departures of precipitation for 1990 were above normal at the Athens (+2.6 in., fig. 2), Atlanta (+9.0 in., fig. 3), and Rome (+8.6 in., fig. 4
Groundwater provides more than 40 percent of California's drinking water. To protect this vital r... more Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State's groundwater quality and increases public access to groundwater-quality information. Owens Valley is one of the study areas being evaluated. The Owens Study Area Overview of Water Quality GAMA's Priority Basin Project evaluates the quality of untreated groundwater. However, for context, benchmarks established for drinking-water quality are used for comparison. Benchmarks and definitions of high, moderate, and low concentrations are discussed in the inset box on page 3. The USGS sampled 40 wells for this assessment; data from the California Department of Public Health database were used to supplement USGS data. Many inorganic constituents occur naturally in groundwater. The concentrations of the inorganic constituents can be affected by natural processes as well as by human activities. In the Owens study area, one or more inorganic constituents were present at high concentrations in 22% of the primary aquifers and at moderate concentrations in 20%. Organic constituents are present in products used in the home, business, industry, and agriculture. Organic constituents can enter the groundwater system through normal usage, spills, or improper disposal. In the Owens study area, no organic constituents were present at high or moderate concentrations.
Groundwater provides more than 40 percent of California's drinking water. To protect this vital r... more Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State's groundwater quality and increases public access to groundwater-quality information. Four groundwater basins along the Mojave River make up one of the study areas being evaluated. The Mojave Study Area Overview of Water Quality GAMA's Priority Basin Project evaluates the quality of untreated groundwater. However, for context, benchmarks established for drinking-water quality are used for comparison. Benchmarks and definitions of high, moderate, and low concentrations are discussed in the inset box on page 3. The USGS sampled 52 wells for this assessment; data from the California Department of Public Health database were used to supplement USGS data. Many inorganic constituents occur naturally in groundwater. The concentrations of the inorganic constituents can be affected by natural processes as well as by human activities. In the Mojave study area, one or more inorganic constituents were present at high concentrations in 28% of the primary aquifers and at moderate concentrations in 36%. Organic constituents are present in products used in the home, business, industry, and agriculture. Organic constituents can enter the groundwater system through normal usage, spills, or improper disposal. In the Mojave study area, organic constituents were present at high concentrations in 2% of the primary aquifers and at moderate concentrations in 6%. The Mojave study area is approximately 1,500 square miles (3,885 square kilometers) and includes four contiguous groundwater basins: Upper, Middle, and Lower Mojave River Groundwater Basins, and the El Mirage Valley (California Department of Water Resources, 2003). The Mojave study area has an arid climate, and is part of the Mojave Desert. Average annual rainfall is about 6 inches (15 centimeters). Land use in the study area is approximately 82 percent (%) natural (mostly shrubland), 4% agricultural, and 14% urban. The primary crops are pasture and hay. The largest urban areas are the cities of Victorville, Hesperia, and Apple Valley (2010 populations of 116,000, 90,000 and 69,000, respectively). Groundwater in these basins is used for public and domestic water supply and for irrigation. The main water-bearing units are gravel, sand, silt, and clay derived from surrounding mountains. The primary aquifers in the Mojave study area are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database. Public-supply wells in the Mojave study area are completed to depths between 200 and 600 feet (18 to 61 meters), consist of solid casing from the land surface to a depth of 130 to 420 feet (40 to 128 meters), and are screened or perforated below the solid casing. Recharge to the groundwater system is primarily runoff from the mountains to the south, mostly through the Mojave River channel. The primary sources of discharge are pumping wells and evapotranspiration. High Moderate CONSTITUENT CONCENTRATIONS Low or not detected Pie charts illustrate the proportion of the primary aquifers, on an areal basis with concentrations in three specified categories.
Groundwater provides more than 40 percent of California's drinking water. To protect this vital r... more Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State's groundwater quality and increases public access to groundwater-quality information. Coachella Valley is one of the study areas being evaluated. GAMA's Priority Basin Project evaluates the quality of untreated groundwater. However, for context, benchmarks established for drinking-water quality are used for comparison. Benchmarks and definitions of high, moderate, and low concentrations are discussed in the inset box on page 3. The USGS sampled 19 wells for this assessment; data from the California Department of Public Health database were used to supplement USGS data. Many inorganic constituents occur naturally in groundwater. The concentrations of the inorganic constituents can be affected by natural processes as well as by human activities. In the Coachella study area, one or more inorganic constituents were present at high concentrations in 42% of the primary aquifers and at moderate concentrations in 26%. Organic constituents are found in products used in the home, business, industry, and agriculture. Organic constituents can enter the groundwater system through normal usage, spills, or improper disposal. In the Coachella study area, organic constituents were present at moderate concentrations in 1% of the primary aquifers. The Coachella study area is approximately 820 square miles (2,124 square kilometers) and includes the Coachella Valley groundwater basin (California Department of Water Resources, 2003). Coachella Valley has an arid climate, with average annual rainfall of about 6 inches (15 centimeters). The runoff from the surrounding mountains drains to rivers that flow east and south out of the study area to the Salton Sea. Land use in the study area is approximately 67 percent (%) natural, 21% agricultural, and 12% urban. The primary natural land cover is shrubland. The largest urban areas are the cities of Indio and Palm Springs (2010 populations of 76,000 and 44,000, respectively). Groundwater in this basin is used for public and domestic water supply and for irrigation. The main water-bearing units are gravel, sand, silt, and clay derived from surrounding mountains. The primary aquifers in Coachella Valley are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database. Public-supply wells in Coachella Valley are completed to depths between 490 and 900 feet (149 to 274 meters), consist of solid casing from the land surface to a depth of 260 to 510 feet (79 to 155 meters), and are screened or perforated below the solid casing. Recharge to the groundwater system is primarily runoff from the surrounding mountains, and by direct infiltration of irrigation. The primary sources of discharge are pumping wells, evapotranspiration, and underflow to the Salton Sea and Imperial Valley areas. The Coachella Study Area Overview of Water Quality High Moderate CONSTITUENT CONCENTRATIONS Low or not detected Pie charts illustrate the percentages of the primary aquifers, on an areal basis, with concentrations in the three specified categories.
Groundwater provides more than 40 percent of California's drinking water. To protect this vital r... more Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State's groundwater quality and increases public access to groundwater-quality information. Antelope Valley is one of the study areas being evaluated. The Antelope Study Area Overview of Water Quality GAMA's Priority Basin Project evaluates the quality of untreated groundwater. However, for context, benchmarks established for drinkingwater quality are used for comparison. Benchmarks and definitions of high, moderate, and low concentrations are discussed in the inset box on page 3. The USGS sampled 56 wells for this assessment; data from the California Department of Public Health database were used to supplement USGS data. Many inorganic constituents occur naturally in groundwater. The concentrations of the inorganic constituents can be affected by natural processes as well as by human activities. In the Antelope Valley study area, one or more inorganic constituents were present at high concentrations in 30% of the primary aquifers and at moderate concentrations in 30%. Organic constituents are found in products used in the home, business, industry, and agriculture. Organic constituents can enter the groundwater system through normal usage, spills, or improper disposal. In the Antelope Valley study area, organic constituents were present at moderate concentrations in 2% of the primary aquifers. The Antelope study area is approximately 1,600 square miles (4,144 square kilometers) and includes the Antelope Valley groundwater basin (California Department of Water Resources, 2003). Antelope Valley has an arid climate and is part of the Mojave Desert. Average annual rainfall is about 6 inches (15 centimeters). The study area has internal drainage, with runoff from the surrounding mountains draining towards dry lakebeds in the lower parts of the valley. Land use in the study area is approximately 68 percent (%) natural (mostly shrubland and grassland), 24% agricultural, and 8% urban. The primary crops are pasture and hay. The largest urban areas are the cities of Palmdale and Lancaster (2010 populations of 152,000 and 156,000, respectively). Groundwater in this basin is used for public and domestic water supply and for irrigation. The main water-bearing units are gravel, sand, silt, and clay derived from surrounding mountains. The primary aquifers in Antelope Valley are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database. Public-supply wells in Antelope Valley are completed to depths between 360 and 700 feet (110 to 213 meters), consist of solid casing from the land surface to a depth of 180 to 350 feet (55 to 107 meters), and are screened or perforated below the solid casing. Recharge to the groundwater system is primarily runoff from the surrounding mountains, and by direct infiltration of irrigation and sewer and septic systems. The primary sources of discharge are pumping wells and evapotranspiration near the dry lakebeds. High Moderate CONSTITUENT CONCENTRATIONS Low or not detected Pie charts illustrate the proportion of the primary aquifers, on an areal basis, with concentrations in the three specified categories.
Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD ... more Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88).
Groundwater provides more than 40 percent of California's drinking water. To protect this vital r... more Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State's groundwater quality and increases public access to groundwater-quality information. Four groundwater basins along the Colorado River make up one of the study areas being evaluated. The Colorado River Study Area Overview of Water Quality GAMA's Priority Basin Project evaluates the quality of untreated groundwater. However, for context, benchmarks established for drinkingwater quality are used for comparison. Benchmarks and definitions of high, moderate, and low concentrations are discussed in the inset box on page 3. The USGS sampled 20 wells for this assessment; data from the California Department of Public Health database were used to supplement USGS data. Many inorganic constituents occur naturally in groundwater. The concentrations of the inorganic constituents can be affected by natural processes as well as by human activities. In the Colorado River study area, one or more inorganic constituents were present at high concentrations in 45% of the primary aquifers and at moderate concentrations in 35%. Organic constituents are present in products used in the home, business, industry, and agriculture. Organic constituents can enter the groundwater system through normal usage, spills, or improper disposal. In the Colorado River study area, organic constituents were present at moderate concentrations in 10% of the primary aquifers.
The NAWQA Program recognizes that a national assessment by a single program cannot address all wa... more The NAWQA Program recognizes that a national assessment by a single program cannot address all waterresource issues of interest. External coordination at all levels is critical for a fully integrated understanding of watersheds and for cost-effective management, regulation, and conservation of our Nation's water resources. The Program, therefore, depends extensively on the advice, cooperation, and information from other Federal, State, interstate, Tribal, and local agencies, non-government organizations, industry, academia, and other stakeholder groups. The assistance and suggestions of all are greatly appreciated.
Map showing northern San Joaquin Basin GroundWater Ambient Monitoring and Assessment (GAMA) study... more Map showing northern San Joaquin Basin GroundWater Ambient Monitoring and Assessment (GAMA) study unit showing study areas, distribution of study area grid cells, and location of sampled grid cell wells ..
Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows: °F=(1... more Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows: °F=(1.8×°C)+32 Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88). Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (µS/cm at 25°C). Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) or micrograms per liter (µg/L). Milligrams per liter is equivalent to parts per million (ppm) and micrograms per liter is equivalent to parts per billion (ppb). x This page intentionally left blank.
One dredge haul from a young East Pacific Rise sqrmount, located approximately 15 km off-axis, re... more One dredge haul from a young East Pacific Rise sqrmount, located approximately 15 km off-axis, recovered exclusively hydrothermal material that included massive sulfide, crusts consisting of euhedral drusy atacamite, and reddish brown iron oxide crusts and mud. The massive sulfide is primarily quartz, pyrite, and sphalerite, with accessory chalcopyrite, covellite, digenite, and galena; the sulfide fraction contains up to 2 ppm Au and 150 ppm Ag. Conditions of formation were estimated from fluid inclusions in quartz. Inclusion trapping temperatures were 240 + 35oC at the ambient seafloor pressure of 26 MPa, and the fluid had 4.0 wt.9o equivalent NaCl. The massive sulfide is atypical because it contains silica as quartz rather than an amorphous variety, suggesting that the usual kinetic barrier to quartz precipitation was overcome. Some of the quartz apparently replaced earlier amorphous silica, but much of it precipitated as primary quartz, entrapping fluid inclusions. Active hot springs on the seafloor that precipitate quartz have not been directly observed; however, these massive sulfides and other quartz-bearing samples from seafloor deposits suggest that subsurface diffuse flow and conductive heatloss may overcome the unfavorable kinetics of quartz precipitation.
Groundwater quality in the approximately 2,100 squaremile Southern Sacramento Valley study unit (... more Groundwater quality in the approximately 2,100 squaremile Southern Sacramento Valley study unit (SSACV) was investigated from March to June 2005 as part of the Statewide Basin Assessment Project of GroundWater Ambient Monitoring and Assessment (GAMA) Program. This study was designed to provide a spatially unbiased assessment of raw groundwater quality within SSACV, as well as a statistically consistent basis for comparing water quality throughout California. Samples were collected from 83 wells in Placer, Sacramento, Solano, Sutter, and Yolo Counties. Sixty-seven of the wells were selected using a randomized grid-based method to provide statistical representation of the study area. Sixteen of the wells were sampled to evaluate changes in water chemistry along groundwater flow paths. Four additional samples were collected at one of the wells to evaluate water-quality changes with depth. The GAMA Statewide Basin Assessment project was developed in response to the GroundWater Quality Monitoring Act of 2001 and is being conducted by the California State Water Resources Control Board (SWRCB) in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory (LLNL). The groundwater samples were analyzed for a large number of man-made organic constituents (volatile organic compounds [VOCs], pesticides and pesticide degradates, pharmaceutical compounds, and wastewater-indicator constituents), constituents of special interest (perchlorate, N-nitrosodimethylamine [NDMA], and 1,2,3-trichloropropane [1,2,3-TCP]), naturally occurring inorganic constituents (nutrients, major and minor ions, and trace elements), radioactive constituents, and microbial indicators. Naturally occurring isotopes (tritium, and carbon-14, and stable isotopes of hydrogen, oxygen, and carbon), and dissolved noble gases also were measured to help identify the source and age of the sampled ground water. Quality-control samples (blanks, replicates, matrix spikes) were collected at ten percent of the wells, and the results for these samples were used to evaluate the quality of the data for the groundwater samples. Assessment of the quality-control data resulted in censoring of less than 0.03 percent of the analyses of groundwater samples. This study did not evaluate the quality of water delivered to consumers; after withdrawal from the ground, water typically is treated, disinfected, and (or) blended with other waters to maintain acceptable water quality. Regulatory thresholds apply to treated water that is served to the consumer, not to raw ground water. However, to provide some context for the results, concentrations of constituents measured in the raw ground water were compared with health-based thresholds established by the U.S. Environmental Protection Agency (USEPA) and California Department of Health Services (CADHS) (Maximum Contaminant Levels [MCLs], notification levels [NLs], or lifetime health advisories [HA-Ls]) and thresholds established for aesthetic concerns (Secondary Maximum Contaminant Levels [SMCLs]). All wells were sampled for organic constituents and selected general water quality parameters; subsets of wells were sampled for inorganic constituents, nutrients, and radioactive constituents. Volatile organic compounds were detected in 49 out of 83 wells sampled and pesticides were detected in 35 out of 82 wells; all detections were below health-based thresholds, with the exception of 1 detection of 1,2,3-trichloropropane above a NL. Of the 43 wells sampled for trace elements, 27 had no detections of a trace element above a health-based threshold and 16 had at least one detection above. Of the 18 trace elements with health-based thresholds, 3 (arsenic, barium, and boron) were detected at concentrations higher an MCL. Of the 43 wells sampled for nitrate, only 1 well had a detection above the MCL. Twenty wells were sampled for radioactive constituents; only 1 (radon-222) was measured at activities higher than the proposed MCL. Radon-222 was detected below the threshold in 7 wells and above the threshold in 13 wells. SMCLs have been established for nine constituents or parameters analyzed in SSACV. Six were measured at levels higher than an SMCL: chloride, iron, manganese, pH, specific conductance, and total dissolved solids. Chloride, iron, manganese, pH, and total dissolved solids were measured in 43 wells: 27 wells had no measurements above a threshold and 16 wells had a measurement above a threshold. Specific conductance was measured in 83 wells. In 68 wells, specific conductance was measured lower than the threshold and in 15 wells it was measured above the threshold Study areas North American (NAM) Solano (SOL) South American (SAM) EXPLANATION Suisun-Fairfield (SUI) Uplands (QPC) Yolo (YOL) Hydrogeologic Setting of the Southern Sacramento Valley Study Unit The Southern Sacramento Valley GAMA study unit lies within the Central Valley and partly within the North Coast Ranges hydrogeologic provinces described by Belitz and others (2003) (fig. 1). The Southern Sacramento Valley GAMA study unit covers an area of approximately 2,100 mi 2 and includes parts of Placer,
Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows: °F=(1... more Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows: °F=(1.8×°C)+32. Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (µS/cm at 25°C). Turbidity is given in nephelometric turbidity units (NTRU). Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) or micrograms per liter (µg/L). Milligrams per liter is equivalent to parts per million (ppm) and micrograms per liter is equivalent to parts per billion (ppb). Concentrations of radioactive constituents in water are given in picocuries per liter (pCi/L). vii Conversion Factors, Datums, and Abbreviations and Acronyms-Continued Datums Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88). Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83). Land-surface altitude, as used in this report, refers to distance above the vertical datum and is reported as feet above mean sea level (ft above msl).
The NAWQA Program recognizes that a national assessment by a single program cannot address all wa... more The NAWQA Program recognizes that a national assessment by a single program cannot address all waterresource issues of interest. External coordination at all levels is critical for a fully integrated understanding of watersheds and for cost-effective management, regulation, and conservation of our Nation's water resources. The Program, therefore, depends extensively on the advice, cooperation, and information from other Federal, State, interstate, Tribal, and local agencies, non-government organizations, industry, academia, and other stakeholder groups. The assistance and suggestions of all are greatly appreciated.
Groundwater conditions during 1990 and recent groundwater level and-quality trends in Georgia wer... more Groundwater conditions during 1990 and recent groundwater level and-quality trends in Georgia were evaluated using data from precipitation, groundwater level , and groundwater quality monitoring networks. Data for 1990 include precipitation records from 10 National Weather Service stations, continuous water-level records from 140 wells, periodic water-level measurements from an additional 1,227 wells, and chloride analyses from 176 wells. Annual mean groundwater levels in Qeorgia hi 1990 ranged from about 11.4 feet lower to about 3.2 feet higher than hi 1989. Of the 76 wells summarized hi this report, 24 had annual mean water levels that were higher than hi 1989. Record-high daily mean water levels were recorded in three wells tapping the Claiborne aquifer and two wells tapping crystalline-rock aquifers. These record highs were from about 0.4 to about 5.0 feet higher than previous record highs. The other 52 wells had annual mean water levels that were lower than hi 1989. Record-low daily mean water levels were recorded hi the Coastal Plain physiographic province hi two wells tapping surficial aquifers, one well tapping the upper Brunswick aquifer, 21 wells tapping the Floridan aquifer system, one well tapping the Claiborne aquifer, one well tapping the Clayton aquifer and seven wells tapping the Cretaceous aquifers and aquifer systems. These record lows were from slightly lower to about 7.8 feet lower than the previous record lows. Comparison of chloride-concentration maps for the Floridan aquifer system hi the coastal area indicates that chloride concentrations hi water from the Floridan aquifer system generally have changed little since 1988. In the coastal area, chloride concentrations hi water from the Upper Floridan aquifer that exceed U.S. Environmental Protection Agency and Georgia Department of Natural Resources, Environmental Protection Division, drinking-water standards have been detected only hi the Brunswick area. In the Brunswick area, changes hi chloride concentrations hi water from the Floridan aquifer system have been mixed. In the southern Brunswick area, chloride concentration hi water from the Lower Floridan aquifer has increased gradually since sampling began hi the late 1960's. In the northeastern Brunswick area, water hi two wells tapping the Upper Floridan aquifer showed trends of decreasing chloride concentrations that began in 1980 and 1984. In the northwestern Brunswick area, water hi two wells tapping the Upper Floridan aquifer showed trends of increasing chloride concentrations that have been present since sampling began hi 1970. In the Savannah area, chloride concentrations have shown little change since 1968, except for an increase hi three wells tapping deep zones of the Lower Floridan aquifer at the end of 1990. Monitoring groundwater levels and quality is essential to water-resources management. Groundwater levels and quality have been monitored in Georgia for about 100 years. In the early years, water-level data were used in areal reconnaissance studies to show water-level trends. These data had limited value for resource-management purposes because of the large period of tiflie between collection and publication of the data. As part of the cooperative groundwater investigations undertaken by the U.S. Geological Survey and the state of Georgia, a statewide water-level-measurement program was begun in 1938. Initially, this program consisted of an observation-well network hi the coastal area of Georgia that provided data concerning variations hi groundwater storage and quality. Additional wells were added water quality could forewarn potential water-resources prob in areas where variations in water levels and ems. During 1990, periodic water-level measurements were made in 1,227 wells, and 140 wells were monitored continuously. Continuous water-level records were obtained using analog (pen and chart) recorders, digital punch recorders that record water levels at 30-minute (min) or 60-min intervals, and data loggers that record water levels at 60-min intervals. At sites with missing record, data were estimated, where possible, using data from nearby wells that showed a similar water-level response to variations in precipitation and pumping. Water samples also were periodically collected and analyzed from 176 wells during 1990 to monitor chloride concentrations in the coastal area. Purpose and Scope Groundwater level and-quality data are an important part of groundwater assessment and management. Water-level data are used to indicate directions of groundwater flow and areas of recharge and discharge; indicate the change in aquifer storage as it is affected by distribution and rate of groundwater withdrawal; help define the hydraulic characteristics of aquifers; evaluate stream-aquifer relations; provide information for addressing water-management needs; and provide long-term records that can be used to evaluate the effects of management and conservation programs. This report continues a series of annual publications that present precipitation, groundwater level , and groundwater quality information for Georgia. Formerly titled "Ground-Water Data for Georgia", the title was changed to "Ground-Water Conditions in Georgia" in 1989 to more accurately reflect its content. Precipitation graphs for 10 National Weather Service stations, hydrographs for 76 wells, and water-level maps of the Upper Floridan, Claiborne, and Clayton aquifers are presented to illustrate the effects that variations in recharge and discharge have had on the various aquifers in the State. Chloride-Concentration graphs for 13 wells tapping the Floridan aquifer system in the coastal area, and chloride-concentration maps for the Upper Floridan aquifer in the coastal and Brunswick areas, have been included to show the distribution and variations in chloride concentration since monitoring began. PRECIPITATION Recharge to the groundwater system in Georgia is derived almost entirely from precipitation. Based on records for 1941-70, annual precipitation averaged 50 inches (in.) statewide, and ranged from 44 in. in the east-central part to about 76 in. in the northeastern corner (fig. 1) (Carter and Stiles, 1983). Of the total annual precipitation, about 88 percent is discharged to streams or is lost to evapotranspiration, and about 12 percent enters the groundwater system as recharge (Carter and Stiles, IS Monthly mean precipitation data furnished by the Administration (1990) are shown graphically for 10 precipitation stations (figs. 2-11). For each station, monthly precipitation was compared to the 30-year (yr) (1951-80) average (normal) for the station. Cumulative departure curves are a method often used to illustrate surplus U.S. National Oceanic and Atmospheric or deficit amounts of precipitation over a designated period of time. The curves used in this report were obtained by adding successive monthly values of precipitation departures from normal. For example, if precipitation in January was 2 in. above normal and in February was 1 in. below normal, the cumulative departure would be (+2) + (-l) = +1 in. Thus, the annual cumulative departure through December would represent the sum of all monthly deficits or surpluses during the year. Similarly, the 10-yr cumulative departure at the end of December would represent the sum of all monthly deficits or surpluses for the previous 119 months. For ;ach of the precipitation stations, the lower graph shows the cumulative departure from normal precipitation for the period 1981-90; the upper graph shows the monthly departure and cumulative departure for 1990. At the end of the year, the cumulative departures of precipitation for 1990 were above normal at the Athens (+2.6 in., fig. 2), Atlanta (+9.0 in., fig. 3), and Rome (+8.6 in., fig. 4
Groundwater provides more than 40 percent of California's drinking water. To protect this vital r... more Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State's groundwater quality and increases public access to groundwater-quality information. Owens Valley is one of the study areas being evaluated. The Owens Study Area Overview of Water Quality GAMA's Priority Basin Project evaluates the quality of untreated groundwater. However, for context, benchmarks established for drinking-water quality are used for comparison. Benchmarks and definitions of high, moderate, and low concentrations are discussed in the inset box on page 3. The USGS sampled 40 wells for this assessment; data from the California Department of Public Health database were used to supplement USGS data. Many inorganic constituents occur naturally in groundwater. The concentrations of the inorganic constituents can be affected by natural processes as well as by human activities. In the Owens study area, one or more inorganic constituents were present at high concentrations in 22% of the primary aquifers and at moderate concentrations in 20%. Organic constituents are present in products used in the home, business, industry, and agriculture. Organic constituents can enter the groundwater system through normal usage, spills, or improper disposal. In the Owens study area, no organic constituents were present at high or moderate concentrations.
Groundwater provides more than 40 percent of California's drinking water. To protect this vital r... more Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State's groundwater quality and increases public access to groundwater-quality information. Four groundwater basins along the Mojave River make up one of the study areas being evaluated. The Mojave Study Area Overview of Water Quality GAMA's Priority Basin Project evaluates the quality of untreated groundwater. However, for context, benchmarks established for drinking-water quality are used for comparison. Benchmarks and definitions of high, moderate, and low concentrations are discussed in the inset box on page 3. The USGS sampled 52 wells for this assessment; data from the California Department of Public Health database were used to supplement USGS data. Many inorganic constituents occur naturally in groundwater. The concentrations of the inorganic constituents can be affected by natural processes as well as by human activities. In the Mojave study area, one or more inorganic constituents were present at high concentrations in 28% of the primary aquifers and at moderate concentrations in 36%. Organic constituents are present in products used in the home, business, industry, and agriculture. Organic constituents can enter the groundwater system through normal usage, spills, or improper disposal. In the Mojave study area, organic constituents were present at high concentrations in 2% of the primary aquifers and at moderate concentrations in 6%. The Mojave study area is approximately 1,500 square miles (3,885 square kilometers) and includes four contiguous groundwater basins: Upper, Middle, and Lower Mojave River Groundwater Basins, and the El Mirage Valley (California Department of Water Resources, 2003). The Mojave study area has an arid climate, and is part of the Mojave Desert. Average annual rainfall is about 6 inches (15 centimeters). Land use in the study area is approximately 82 percent (%) natural (mostly shrubland), 4% agricultural, and 14% urban. The primary crops are pasture and hay. The largest urban areas are the cities of Victorville, Hesperia, and Apple Valley (2010 populations of 116,000, 90,000 and 69,000, respectively). Groundwater in these basins is used for public and domestic water supply and for irrigation. The main water-bearing units are gravel, sand, silt, and clay derived from surrounding mountains. The primary aquifers in the Mojave study area are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database. Public-supply wells in the Mojave study area are completed to depths between 200 and 600 feet (18 to 61 meters), consist of solid casing from the land surface to a depth of 130 to 420 feet (40 to 128 meters), and are screened or perforated below the solid casing. Recharge to the groundwater system is primarily runoff from the mountains to the south, mostly through the Mojave River channel. The primary sources of discharge are pumping wells and evapotranspiration. High Moderate CONSTITUENT CONCENTRATIONS Low or not detected Pie charts illustrate the proportion of the primary aquifers, on an areal basis with concentrations in three specified categories.
Groundwater provides more than 40 percent of California's drinking water. To protect this vital r... more Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State's groundwater quality and increases public access to groundwater-quality information. Coachella Valley is one of the study areas being evaluated. GAMA's Priority Basin Project evaluates the quality of untreated groundwater. However, for context, benchmarks established for drinking-water quality are used for comparison. Benchmarks and definitions of high, moderate, and low concentrations are discussed in the inset box on page 3. The USGS sampled 19 wells for this assessment; data from the California Department of Public Health database were used to supplement USGS data. Many inorganic constituents occur naturally in groundwater. The concentrations of the inorganic constituents can be affected by natural processes as well as by human activities. In the Coachella study area, one or more inorganic constituents were present at high concentrations in 42% of the primary aquifers and at moderate concentrations in 26%. Organic constituents are found in products used in the home, business, industry, and agriculture. Organic constituents can enter the groundwater system through normal usage, spills, or improper disposal. In the Coachella study area, organic constituents were present at moderate concentrations in 1% of the primary aquifers. The Coachella study area is approximately 820 square miles (2,124 square kilometers) and includes the Coachella Valley groundwater basin (California Department of Water Resources, 2003). Coachella Valley has an arid climate, with average annual rainfall of about 6 inches (15 centimeters). The runoff from the surrounding mountains drains to rivers that flow east and south out of the study area to the Salton Sea. Land use in the study area is approximately 67 percent (%) natural, 21% agricultural, and 12% urban. The primary natural land cover is shrubland. The largest urban areas are the cities of Indio and Palm Springs (2010 populations of 76,000 and 44,000, respectively). Groundwater in this basin is used for public and domestic water supply and for irrigation. The main water-bearing units are gravel, sand, silt, and clay derived from surrounding mountains. The primary aquifers in Coachella Valley are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database. Public-supply wells in Coachella Valley are completed to depths between 490 and 900 feet (149 to 274 meters), consist of solid casing from the land surface to a depth of 260 to 510 feet (79 to 155 meters), and are screened or perforated below the solid casing. Recharge to the groundwater system is primarily runoff from the surrounding mountains, and by direct infiltration of irrigation. The primary sources of discharge are pumping wells, evapotranspiration, and underflow to the Salton Sea and Imperial Valley areas. The Coachella Study Area Overview of Water Quality High Moderate CONSTITUENT CONCENTRATIONS Low or not detected Pie charts illustrate the percentages of the primary aquifers, on an areal basis, with concentrations in the three specified categories.
Groundwater provides more than 40 percent of California's drinking water. To protect this vital r... more Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State's groundwater quality and increases public access to groundwater-quality information. Antelope Valley is one of the study areas being evaluated. The Antelope Study Area Overview of Water Quality GAMA's Priority Basin Project evaluates the quality of untreated groundwater. However, for context, benchmarks established for drinkingwater quality are used for comparison. Benchmarks and definitions of high, moderate, and low concentrations are discussed in the inset box on page 3. The USGS sampled 56 wells for this assessment; data from the California Department of Public Health database were used to supplement USGS data. Many inorganic constituents occur naturally in groundwater. The concentrations of the inorganic constituents can be affected by natural processes as well as by human activities. In the Antelope Valley study area, one or more inorganic constituents were present at high concentrations in 30% of the primary aquifers and at moderate concentrations in 30%. Organic constituents are found in products used in the home, business, industry, and agriculture. Organic constituents can enter the groundwater system through normal usage, spills, or improper disposal. In the Antelope Valley study area, organic constituents were present at moderate concentrations in 2% of the primary aquifers. The Antelope study area is approximately 1,600 square miles (4,144 square kilometers) and includes the Antelope Valley groundwater basin (California Department of Water Resources, 2003). Antelope Valley has an arid climate and is part of the Mojave Desert. Average annual rainfall is about 6 inches (15 centimeters). The study area has internal drainage, with runoff from the surrounding mountains draining towards dry lakebeds in the lower parts of the valley. Land use in the study area is approximately 68 percent (%) natural (mostly shrubland and grassland), 24% agricultural, and 8% urban. The primary crops are pasture and hay. The largest urban areas are the cities of Palmdale and Lancaster (2010 populations of 152,000 and 156,000, respectively). Groundwater in this basin is used for public and domestic water supply and for irrigation. The main water-bearing units are gravel, sand, silt, and clay derived from surrounding mountains. The primary aquifers in Antelope Valley are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database. Public-supply wells in Antelope Valley are completed to depths between 360 and 700 feet (110 to 213 meters), consist of solid casing from the land surface to a depth of 180 to 350 feet (55 to 107 meters), and are screened or perforated below the solid casing. Recharge to the groundwater system is primarily runoff from the surrounding mountains, and by direct infiltration of irrigation and sewer and septic systems. The primary sources of discharge are pumping wells and evapotranspiration near the dry lakebeds. High Moderate CONSTITUENT CONCENTRATIONS Low or not detected Pie charts illustrate the proportion of the primary aquifers, on an areal basis, with concentrations in the three specified categories.
Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD ... more Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88).
Groundwater provides more than 40 percent of California's drinking water. To protect this vital r... more Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State's groundwater quality and increases public access to groundwater-quality information. Four groundwater basins along the Colorado River make up one of the study areas being evaluated. The Colorado River Study Area Overview of Water Quality GAMA's Priority Basin Project evaluates the quality of untreated groundwater. However, for context, benchmarks established for drinkingwater quality are used for comparison. Benchmarks and definitions of high, moderate, and low concentrations are discussed in the inset box on page 3. The USGS sampled 20 wells for this assessment; data from the California Department of Public Health database were used to supplement USGS data. Many inorganic constituents occur naturally in groundwater. The concentrations of the inorganic constituents can be affected by natural processes as well as by human activities. In the Colorado River study area, one or more inorganic constituents were present at high concentrations in 45% of the primary aquifers and at moderate concentrations in 35%. Organic constituents are present in products used in the home, business, industry, and agriculture. Organic constituents can enter the groundwater system through normal usage, spills, or improper disposal. In the Colorado River study area, organic constituents were present at moderate concentrations in 10% of the primary aquifers.
The NAWQA Program recognizes that a national assessment by a single program cannot address all wa... more The NAWQA Program recognizes that a national assessment by a single program cannot address all waterresource issues of interest. External coordination at all levels is critical for a fully integrated understanding of watersheds and for cost-effective management, regulation, and conservation of our Nation's water resources. The Program, therefore, depends extensively on the advice, cooperation, and information from other Federal, State, interstate, Tribal, and local agencies, non-government organizations, industry, academia, and other stakeholder groups. The assistance and suggestions of all are greatly appreciated.
Map showing northern San Joaquin Basin GroundWater Ambient Monitoring and Assessment (GAMA) study... more Map showing northern San Joaquin Basin GroundWater Ambient Monitoring and Assessment (GAMA) study unit showing study areas, distribution of study area grid cells, and location of sampled grid cell wells ..
Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows: °F=(1... more Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows: °F=(1.8×°C)+32 Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88). Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (µS/cm at 25°C). Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) or micrograms per liter (µg/L). Milligrams per liter is equivalent to parts per million (ppm) and micrograms per liter is equivalent to parts per billion (ppb). x This page intentionally left blank.
One dredge haul from a young East Pacific Rise sqrmount, located approximately 15 km off-axis, re... more One dredge haul from a young East Pacific Rise sqrmount, located approximately 15 km off-axis, recovered exclusively hydrothermal material that included massive sulfide, crusts consisting of euhedral drusy atacamite, and reddish brown iron oxide crusts and mud. The massive sulfide is primarily quartz, pyrite, and sphalerite, with accessory chalcopyrite, covellite, digenite, and galena; the sulfide fraction contains up to 2 ppm Au and 150 ppm Ag. Conditions of formation were estimated from fluid inclusions in quartz. Inclusion trapping temperatures were 240 + 35oC at the ambient seafloor pressure of 26 MPa, and the fluid had 4.0 wt.9o equivalent NaCl. The massive sulfide is atypical because it contains silica as quartz rather than an amorphous variety, suggesting that the usual kinetic barrier to quartz precipitation was overcome. Some of the quartz apparently replaced earlier amorphous silica, but much of it precipitated as primary quartz, entrapping fluid inclusions. Active hot springs on the seafloor that precipitate quartz have not been directly observed; however, these massive sulfides and other quartz-bearing samples from seafloor deposits suggest that subsurface diffuse flow and conductive heatloss may overcome the unfavorable kinetics of quartz precipitation.
Groundwater quality in the approximately 2,100 squaremile Southern Sacramento Valley study unit (... more Groundwater quality in the approximately 2,100 squaremile Southern Sacramento Valley study unit (SSACV) was investigated from March to June 2005 as part of the Statewide Basin Assessment Project of GroundWater Ambient Monitoring and Assessment (GAMA) Program. This study was designed to provide a spatially unbiased assessment of raw groundwater quality within SSACV, as well as a statistically consistent basis for comparing water quality throughout California. Samples were collected from 83 wells in Placer, Sacramento, Solano, Sutter, and Yolo Counties. Sixty-seven of the wells were selected using a randomized grid-based method to provide statistical representation of the study area. Sixteen of the wells were sampled to evaluate changes in water chemistry along groundwater flow paths. Four additional samples were collected at one of the wells to evaluate water-quality changes with depth. The GAMA Statewide Basin Assessment project was developed in response to the GroundWater Quality Monitoring Act of 2001 and is being conducted by the California State Water Resources Control Board (SWRCB) in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory (LLNL). The groundwater samples were analyzed for a large number of man-made organic constituents (volatile organic compounds [VOCs], pesticides and pesticide degradates, pharmaceutical compounds, and wastewater-indicator constituents), constituents of special interest (perchlorate, N-nitrosodimethylamine [NDMA], and 1,2,3-trichloropropane [1,2,3-TCP]), naturally occurring inorganic constituents (nutrients, major and minor ions, and trace elements), radioactive constituents, and microbial indicators. Naturally occurring isotopes (tritium, and carbon-14, and stable isotopes of hydrogen, oxygen, and carbon), and dissolved noble gases also were measured to help identify the source and age of the sampled ground water. Quality-control samples (blanks, replicates, matrix spikes) were collected at ten percent of the wells, and the results for these samples were used to evaluate the quality of the data for the groundwater samples. Assessment of the quality-control data resulted in censoring of less than 0.03 percent of the analyses of groundwater samples. This study did not evaluate the quality of water delivered to consumers; after withdrawal from the ground, water typically is treated, disinfected, and (or) blended with other waters to maintain acceptable water quality. Regulatory thresholds apply to treated water that is served to the consumer, not to raw ground water. However, to provide some context for the results, concentrations of constituents measured in the raw ground water were compared with health-based thresholds established by the U.S. Environmental Protection Agency (USEPA) and California Department of Health Services (CADHS) (Maximum Contaminant Levels [MCLs], notification levels [NLs], or lifetime health advisories [HA-Ls]) and thresholds established for aesthetic concerns (Secondary Maximum Contaminant Levels [SMCLs]). All wells were sampled for organic constituents and selected general water quality parameters; subsets of wells were sampled for inorganic constituents, nutrients, and radioactive constituents. Volatile organic compounds were detected in 49 out of 83 wells sampled and pesticides were detected in 35 out of 82 wells; all detections were below health-based thresholds, with the exception of 1 detection of 1,2,3-trichloropropane above a NL. Of the 43 wells sampled for trace elements, 27 had no detections of a trace element above a health-based threshold and 16 had at least one detection above. Of the 18 trace elements with health-based thresholds, 3 (arsenic, barium, and boron) were detected at concentrations higher an MCL. Of the 43 wells sampled for nitrate, only 1 well had a detection above the MCL. Twenty wells were sampled for radioactive constituents; only 1 (radon-222) was measured at activities higher than the proposed MCL. Radon-222 was detected below the threshold in 7 wells and above the threshold in 13 wells. SMCLs have been established for nine constituents or parameters analyzed in SSACV. Six were measured at levels higher than an SMCL: chloride, iron, manganese, pH, specific conductance, and total dissolved solids. Chloride, iron, manganese, pH, and total dissolved solids were measured in 43 wells: 27 wells had no measurements above a threshold and 16 wells had a measurement above a threshold. Specific conductance was measured in 83 wells. In 68 wells, specific conductance was measured lower than the threshold and in 15 wells it was measured above the threshold Study areas North American (NAM) Solano (SOL) South American (SAM) EXPLANATION Suisun-Fairfield (SUI) Uplands (QPC) Yolo (YOL) Hydrogeologic Setting of the Southern Sacramento Valley Study Unit The Southern Sacramento Valley GAMA study unit lies within the Central Valley and partly within the North Coast Ranges hydrogeologic provinces described by Belitz and others (2003) (fig. 1). The Southern Sacramento Valley GAMA study unit covers an area of approximately 2,100 mi 2 and includes parts of Placer,
Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows: °F=(1... more Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows: °F=(1.8×°C)+32. Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (µS/cm at 25°C). Turbidity is given in nephelometric turbidity units (NTRU). Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) or micrograms per liter (µg/L). Milligrams per liter is equivalent to parts per million (ppm) and micrograms per liter is equivalent to parts per billion (ppb). Concentrations of radioactive constituents in water are given in picocuries per liter (pCi/L). vii Conversion Factors, Datums, and Abbreviations and Acronyms-Continued Datums Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88). Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83). Land-surface altitude, as used in this report, refers to distance above the vertical datum and is reported as feet above mean sea level (ft above msl).
The NAWQA Program recognizes that a national assessment by a single program cannot address all wa... more The NAWQA Program recognizes that a national assessment by a single program cannot address all waterresource issues of interest. External coordination at all levels is critical for a fully integrated understanding of watersheds and for cost-effective management, regulation, and conservation of our Nation's water resources. The Program, therefore, depends extensively on the advice, cooperation, and information from other Federal, State, interstate, Tribal, and local agencies, non-government organizations, industry, academia, and other stakeholder groups. The assistance and suggestions of all are greatly appreciated.
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