The map graphic image at https://www.sciencebase.gov/catalog/file/get/63140561d34e36012efa2b7f?name=arsenic_map.png illustrates arsenic values, in micrograms per liter, for groundwater samples from about 31,000 wells and springs in 49 states compiled by the United States Geological Survey (USGS). The map graphic illustrates an updated version of figure 1 from Ryker (2001). Cited Reference: Ryker, S.J., Nov. 2001, Mapping arsenic in groundwater-- A real need, but a hard problem: Geotimes Newsmagazine of the Earth Sciences, v. 46 no. 11, p. 34-36 at http://www.agiweb.org/geotimes/nov01/feature_Asmap.html. An excel tabular data file, a txt file, along with a GIS shape file of arsenic concentrations (20,043 samples collected by the USGS) for a subset of the sites shown on the map. Samples were collected between 1973 and 2001 and are provided for download.

Maps of Great Basin groundwater geochemistry show distinctive regional spatial patterns. Factors affecting the concentrations of dissolved constituents include bedrock lithology, location within structural zones, geothermal systems, and surficial playa deposits and salt lakes. In this study, a large geochemical database of 51,577 Great Basin groundwater samples from springs and wells was compiled from multiple sources. These data were uploaded into a geographic information system (GIS) and used to produce concentration maps for As, B, Ba, Ca, Cl, F, Fe, HCO3, K, Li, Mn, Mg, Na, SiO2, and SO4. These maps were then examined to identify geologic factors that might have influenced their concentration, including the presence of geothermal systems.

The aquifer risk map is being developed to fulfill requirements of SB-200 and is intended to help prioritize areas where domestic wells and state small water systems may be accessing groundwater that does not meet primary drinking water standards (maximum contaminant level or MCL). In accordance with SB-200, the risk map is to be made available to the public and is to be updated annually starting January 1, 2021. The Fund Expenditure Plan states the risk map will be used by Water Boards staff to help prioritize areas for available SAFER funding..Methodology for the draft aquifer risk map available for download.This layer shows declustered water quality data for arsenic, nitrate, 1,2,3-trichloropropane, per square mile section that was used to create the aquifer risk map required by SB-200. The intent of the aquifer risk map is to help prioritize areas where domestic well users and state small water systems may be accessing groundwater that does not meet primary drinking water standards (maximum contaminant level or MCL) and will be updated annually starting January 1, 2021.

The section water quality data is based on depth-filtered water quality results from public and domestic supply wells, collected following a similar methodology as the Domestic Well Needs Assessment White Paper. This layer contains the long-term average (20 years) as well as the count of recent results (within 2 years) above the MCL, between 80% - 100% of the MCL, and below 80% of the MCL for each square mile section.

[From Arsenic in ground water of the United States, "http://water.usgs.gov/nawqa/trace/arsenic/"

Arsenic is a naturally occurring element in the environment. Arsenic in ground water is largely the result of minerals dissolving naturally from weathered rocks and soils. Several types of cancer have been linked to arsenic in water. The US Environmental Protection Agency is currently reviewing the maximum contaminant level of arsenic permitted in drinking water, and will likely lower it, as recommended last year by the National Research Council.

The USGS has developed a map that shows where and to what extent arsenic occurs in ground water across the country. Highest concentrations were found throughout the West and in parts of the Midwest and Northeast.

Supporting data for "Surface Flooding as a Key Driver of Groundwater Arsenic Contamination in Southeast Asia" (ES&T, 10.1021/acs.est.1c05955)User Information:Read me file (read_me.txt)RMarkdown html file (r_markdown.html)RMarkdown Rmd file (r_markdown.Rmd)Datasets:Data to generate results and analysis (input_dataset.csv)Model output data table (output_dataset.csv)30 m-resolution groundwater arsenic prediction maps:Concentrations (output_data_concentration_30m.tif)Probability > 10 ug/L (output_data_probability_10_30m.tif)Probability > 50 ug/L (output_data_probability_50_30m.tif)Probability > 100 ug/L (output_data_probability_100_30m.tif)1 km-resolution groundwater arsenic prediction maps:Concentrations (output_data_concentration_1km.tif)Probability > 10 ug/L (output_data_probability_10_1km.tif)Probability > 50 ug/L (output_data_probability_50_1km.tif)Probability > 100 ug/L (output_data_probability_100_1km.tif)

AS2021-09-08

The map accompanies the SOLAW report 8 “Agriculture and water quality interactions†. Arsenic contamination in groundwater has been reported in more than 20 countries around the world and, in many, shallow groundwater is used for both drinking and irrigation purposes. Natural arsenic in groundwater at concentrations above the drinking water standard of 10 µg/litre is not uncommon, and the realization that water resources can contain insidious toxic concentrations of naturally-occurring chemical constituents, such as arsenic, is fairly recent and increasingly urgent. First estimates of arsenic toxicity (arsenosis) from drinking water, causing skin lesions and various types of cancers, indicate about 130 million people are impacted. Although the main geochemical mechanisms of arsenic mobilization are well understood, and there are important cases reported around the world, the real worldwide scale of affected regions is still unknown. Amini. et al 2008 conducted a study using a large database of measured arsenic concentration in groundwater (around 20,000 data points) from around the world as well as digital maps of physical characteristics such as soil, geology, climate, and elevation to model probability maps of global arsenic contamination. This map therefore shows, at global scale, probability of geogenic arsenic contamination in groundwater for oxidizing groundwater conditions, based on modelling the above information.

Documented in this data release are data used to model and map the probability of arsenic being greater than 10 micrograms per liter in private domestic wells throughout the conterminous United States during drought conditions (Lombard and others, 2020). The model used to predict the probability of arsenic exceeding 10 micrograms per liter in private domestic wells was previously developed and documented by Ayotte and others (2017). Independent variables in the model include groundwater recharge and annual precipitation. In order to assess the impact of drought these variables were altered to simulate drought by reducing the 30-year average annual values by 25 and 50 percent. The impact of drought was also assessed by using groundwater recharge and precipitation values from the year 2012 when approximately 66 percent of the contiguous United States experienced drought. Data sources for groundwater recharge and precipitation for the year 2012 differ from those used in the original model and the drought simulations, therefore a 30-year average climate model was also produced using these new data sources (Thornton and others, 2018; Hay, 2019). Data are documented from the original model, the drought simulations with reduced values of groundwater recharge and precipitation, the year 2012 and the average annual precipitation and groundwater recharge from 1981 - 2010 from the new data sources.
The model input data that were used to make the prediction maps are within a zipped folder (Prediction_Input_Data.zip) that contains 50 files, one for each model predictor variable. These include the predictor variables from the original model as well as the updated precipitation and groundwater recharge variables for the year 2012 and the average annual values based on the years1981 - 2010, and groundwater recharge and precipitation variables that were systematically decreased for drought simulations. The model prediction outputs are within a zipped folder (Prediction_Output_Data.zip) that contains 10 tif-format raster files, one for each of the eight drought simulations, one for the year 2012, and one for the updated average annual precipitation and groundwater recharge variables for 1981 - 2010. A third zipped folder (Change_Prob_Maps.zip) contains 10 tif-raster files that show the change in probability of arsenic exceeding 10 micrograms per liter in private domestic wells based on the drought simulations and the data used for the year 2012.

Three hundred million people worldwide are at risk of irreversible crippling disorders, internal cancers, and early mortality due to consumption of groundwater containing naturally occurring ("geogenic") arsenic and fluoride. In recent years, there has been increasing public interest to appropriately manage and protect high-quality groundwater aquifers for drinking water and irrigation in drought-stricken regions (e.g., Western U.S., India, etc.). Our project aims to map the co-occurrence of multiple contaminants since most maps currently focus on an individual contaminant.

This is the 2022 version of the Aquifer Risk Map. The 2021 version of the Aquifer Risk Map is available here.This aquifer risk map is developed to fulfill requirements of SB-200 and is intended to help prioritize areas where domestic wells and state small water systems may be accessing raw source groundwater that does not meet primary drinking water standards (maximum contaminant level or MCL). In accordance with SB-200, the risk map is to be made available to the public and is to be updated annually starting January 1, 2021. The Fund Expenditure Plan states the risk map will be used by Water Boards staff to help prioritize areas for available SAFER funding. This is the final 2022 map based upon feedback received from the 2021 map. A summary of methodology updates to the 2022 map can be found here.This map displays raw source groundwater quality risk per square mile section. The water quality data is based on depth-filtered, declustered water quality results from public and domestic supply wells. The process used to create this map is described in the 2022 Aquifer Risk Map Methodology document. Data processing scripts are available on GitHub. Download/export links are provided in this app under the Data Download widget.This draft version was last updated December 1, 2021. Water quality risk: This layer contains summarized water quality risk per square mile section and well point. The section water quality risk is determined by analyzing the long-tern (20-year) section average and the maximum recent (within 5 years) result for all sampled contaminants. These values are compared to the MCL and sections with values above the MCL are “high risk”, sections with values within 80%-100% of the MCL are “medium risk” and sections with values below 80% of the MCL are “low risk”. The specific contaminants above or close to the MCL are listed as well. The water quality data is based on depth-filtered, de-clustered water quality results from public and domestic supply wells.Individual contaminants: This layer shows de-clustered water quality data for arsenic, nitrate, 1,2,3-trichloropropane, uranium, and hexavalent chromium per square mile section. Domestic Well Density: This layer shows the count of domestic well records per square mile. The domestic well density per square mile is based on well completion report data from the Department of Water Resources Online System for Well Completion Reports, with records drilled prior to 1970 removed and records of “destruction” removed.State Small Water Systems: This layer displays point locations for state small water systems based on location data from the Division of Drinking Water.Public Water System Boundaries: This layer displays the approximate service boundaries for public water systems based on location data from the Division of Drinking Water.Reference layers: This layer contains several reference boundaries, including boundaries of CV-SALTS basins with their priority status, Groundwater Sustainability Agency boundaries, census block group boundaries, county boundaries, and groundwater unit boundaries. ArcGIS Web Application

This is the map image layer. The feature layer is available here.The aquifer risk map is being developed to fulfill requirements of SB-200 and is intended to help prioritize areas where domestic wells and state small water systems may be accessing groundwater that does not meet primary drinking water standards (maximum contaminant level or MCL). In accordance with SB-200, the risk map is to be made available to the public and is to be updated annually starting January 1, 2021. This layer is part of the 2022 Aquifer Risk Map. The Fund Expenditure Plan states the risk map will be used by Water Boards staff to help prioritize areas for available SAFER funding.This layer shows water quality risk per square mile section for five individual contaminants: arsenic, nitrate, 1,2,3-trichloropropane, uranium, and hexavalent chromium. The section water quality data is based on de-clustered, depth-filtered water quality results from public and domestic supply wells. This layer contains the long-term average (20 years) as well as the count of recent results (within 5 years) above the MCL, between 80% - 100% of the MCL, and below 80% of the MCL for each square mile section.Detailed methodology can be found [here].

The aquifer risk map is being developed to fulfill requirements of SB-200 and is intended to help prioritize areas where domestic wells and state small water systems may be accessing groundwater that does not meet primary drinking water standards (maximum contaminant level or MCL). In accordance with SB-200, the risk map is to be made available to the public and is to be updated annually starting January 1, 2021. The Fund Expenditure Plan states the risk map will be used by Water Boards staff to help prioritize areas for available SAFER funding.Methodology for the draft aquifer risk map available for download.Water quality risk: This layer contains summarized water quality risk per census block group, square mile section, and well point. The overall census block group water quality risk is based on four risk factors (the count of chemicals with a long-term average (20 year) or recent result (within 2 years) above the MCL, the count of chemicals with a long-term average (20 year) or recent result (within 2 years) within 80% of the MCL, the average magnitude or results above the MCL, and the percent area with chemicals above the MCL or within 80% of the MCL). The specific chemicals that contribute to these risk factors are listed as well. Higher values for each individual risk factor contribute to a higher overall score. The scores are converted to percentiles to normalize the results. The water quality data is based on depth-filtered, declustered water quality results from public and domestic supply wells, collected following a similar methodology as the Domestic Well Needs Assessment White Paper. This layer also displays the total estimated count of domestic wells per census block group, based on the Department of Water Resources Online System for Well Completion Reports, and the total estimated count of domestic well user population, based on the United States Geological Survey Road-Enhanced Methodology (Johnson and Belitz, 2019). To provide comments or feedback on this map, please email SAFER@waterboards.ca.gov or Emily.Houlihan@Waterboards.ca.gov. Individual chemicals: This layer shows declustered water quality data for arsenic, nitrate, 1,2,3-trichloropropane, uranium, and hexavalent chromium per square mile section. The intent of the aquifer risk map is to help prioritize areas where domestic well users and state small water systems may be accessing groundwater that does not meet primary drinking water standards (maximum contaminant level or MCL) and will be updated annually starting January 1, 2021. The section water quality data is based on depth-filtered water quality results from public and domestic supply wells, collected following a similar methodology as the Domestic Well Needs Assessment White Paper. This layer contains the long-term average (20 years) as well as the count of recent results (within 2 years) above the MCL, between 80% - 100% of the MCL, and below 80% of the MCL for each square mile section. Drinking water users: This layer shows the locations of state small water systems and domestic well density. The state small water system locations were collected by the Rural Community Assistance Corporation. The locations are approximate and may not exactly represent well locations or service boundaries. The domestic well density per square mile is based on well completion report data from the Department of Water Resources Online System for Well Completion Reports. This layer also contains the public water system boundaries (available on the State Water Board REST endpoint) for reference.Reference layers: This layer contains several reference boundaries, including boundaries of CV-SALTS basins with their priority status, Groundwater Sustainability Agency boundaries, census block group boundaries, county boundaries, and groundwater unit boundaries.

Nature of natural, ubiquitously over-embossed groundwater. Achieving good quality groundwater status is one of the objectives of the EU Water Framework Directive (WFD). In this context, among other things, the State Geological Services of Germany (SGD) commissioned the group of persons background values groundwater (PK HGW) with the determination and statistical interpretation of the background values in groundwater in 2005. As a result, a comprehensive overview of aquifer-related background levels in groundwaters in Germany was compiled for hydrochemically similar units (HGCs). The results and method documentation are available on the website of the Federal Institute for Geosciences and Natural Resources (BGR) . Preceding the nationwide processing partly, but also as a result, descriptions of the natural groundwater condition in the sense of geogenous background values were made by some geological state services. The country-specific processing made it possible to examine the hydrogeochemical units in more detail by means of a greater differentiation of the hydrogeochemical units. The nature of natural, ubiquitously over-embossed groundwater in Rhineland-Palatinate was investigated on a cartographic basis of the HÜK200 and the results report was published in 2012. The online map on the nature of natural, ubiquitously over-embossed groundwater shows the substance-specific concentrations for the hydrochemical units differentiated in Rhineland-Palatinate. For each hydrochemical unit, the median value (50% percentile) of the corresponding parameter is given. The given median values represent orientation variables in the assessment of the natural, ubiquitously overstamped groundwater properties and replace non-site-based on-site investigations.

The geologic map of the Stitzer and western part of the Montfort quadrangles includes 1:24,000-scale mapping of both surficial and bedrock geology. This area occurs at the northern margin of the historic Upper Mississippi Valley lead and zinc mining district. Paleozoic strata are folded into a regionally-significant anticline, and mapping was initiated to investigate the possible release of groundwater contaminants such as arsenic into the groundwater. Dataset 1 provides the geologic map data in the geologic map schema (GeMS) format.

The aquifer risk map is being developed to fulfill requirements of SB-200 and is intended to help prioritize areas where domestic wells and state small water systems may be accessing groundwater that does not meet primary drinking water standards (maximum contaminant level or MCL). In accordance with SB-200, the risk map is to be made available to the public and is to be updated annually starting January 1, 2021. The Fund Expenditure Plan states the risk map will be used by Water Boards staff to help prioritize areas for available SAFER funding..Methodology for the draft aquifer risk map available for download.This layer shows declustered water quality data for arsenic, nitrate, 1,2,3-trichloropropane, per square mile section that was used to create the aquifer risk map required by SB-200. The intent of the aquifer risk map is to help prioritize areas where domestic well users and state small water systems may be accessing groundwater that does not meet primary drinking water standards (maximum contaminant level or MCL) and will be updated annually starting January 1, 2021.

The section water quality data is based on depth-filtered water quality results from public and domestic supply wells, collected following a similar methodology as the Domestic Well Needs Assessment White Paper. This layer contains the long-term average (20 years) as well as the count of recent results (within 2 years) above the MCL, between 80% - 100% of the MCL, and below 80% of the MCL for each square mile section.

The groundwater resources in different areas of Pakistan are heading towards depletion along with the deterioration of quality due to over-abstraction and urbanization. The main focus of this study is to map the current hydrostratigraphical and hydraulic conditions of the late Quaternary aquifers in the central part of Thal Doab of Punjab Plains. To achieve the target, a comprehensive approach was employed combining geophysical investigations using electrical resistivity surveys (ERS) and physiochemical analysis of groundwater specimens collected from the study area. Careful calibration of resistivity models was performed by comparing them with lithologs to ensure their accuracy. The current groundwater conditions were assessed through thirty vertical electrical soundings (VES) using the Schlumberger electrode configuration up to 300m of AB/2. The interpreted results revealed the presence of four to six geo-electric sublayers comprising the intermixing layers of clay, silt, sand, gravel, and kankar inclusions. These layers exhibited very low (230 Ω-m) resistivity zones at various depth intervals. The developed 2D/3D models of aquifer systems identify the promising areas of good/fresh quality groundwater in the regions characterized by medium to very high resistivity mainly within the sand with gravel layers. However, lower resistivity values indicate the presence of marginally suitable/fair and saline/brackish groundwater showing the existence of fine sediments such as clays/silts. Additionally, twenty groundwater samples were collected to assess various parameters including pH, TDS, arsenic, fluoride, iron, nitrate, and nitrite. The spatial distribution of these parameters was visualized using 2D maps. The suitability of the groundwater for drinking consumption was evaluated in accordance with WHO guidelines.

The aquifer risk map is being developed to fulfill requirements of SB-200 and is intended to help prioritize areas where domestic wells and state small water systems may be accessing groundwater that does not meet primary drinking water standards (maximum contaminant level or MCL). In accordance with SB-200, the risk map is to be made available to the public and is to be updated annually starting January 1, 2021. The Fund Expenditure Plan states the risk map will be used by Water Boards staff to help prioritize areas for available SAFER funding..Methodology for the draft aquifer risk map available for download.This layer shows declustered water quality data for arsenic, nitrate, 1,2,3-trichloropropane, per square mile section that was used to create the aquifer risk map required by SB-200. The intent of the aquifer risk map is to help prioritize areas where domestic well users and state small water systems may be accessing groundwater that does not meet primary drinking water standards (maximum contaminant level or MCL) and will be updated annually starting January 1, 2021.

The section water quality data is based on depth-filtered water quality results from public and domestic supply wells, collected following a similar methodology as the Domestic Well Needs Assessment White Paper. This layer contains the long-term average (20 years) as well as the count of recent results (within 2 years) above the MCL, between 80% - 100% of the MCL, and below 80% of the MCL for each square mile section.

Garber-Wellington - Groundwater Wells with Maximum Trace Metal Concentrations Assessment of Distribution of Arsenic, Chromium, Selenium and Uranium in Groundwater in the Garber-Wellington Aquifer - Central Oklahoma.

The Garber Wellington Aquifer (GWA) in central Oklahoma is a major bedrock aquifer comprised of interbedded sandstone, shale and mudstone that yields significant quantities of water for municipal, industrial, agriculture and domestic beneficial uses. This aquifer also is characterized by locally elevated naturally occurring levels of arsenic, chromium, selenium and uranium. The aquifer underlies parts or all of Cleveland, Lincoln, Logan, Oklahoma and Pottawatomie counties, and these major cities: Oklahoma City, Edmond, Del City, Guthrie, Midwest City, Moore, Nichols Hills, and Norman. These communities, and industries (such as Tinker Air Force Base) and businesses within their confines rely wholly or partly on the aquifer for water supply. In addition, domestic wells supply drinking water to thousands of individuals where public water supply distribution systems do not exist. Unlike public water supply entities that regularly have their municipal water tested and are required to provide water to their customers that meets the Environmental Protection Agency's mandated maximum contaminant levels (MCLs) for these constituents, domestic supply wells are not required to be regularly tested and many homeowners or prospective homeowners relying on water from domestic wells may be completely in the dark to the potential of drinking water with elevated levels of these constituents. The purpose of this project is to provide public access to increase awareness of water quality indicator information of these trace metals. The project indicator information to be disseminated to the public constitutes historical laboratory analytical records "data mined" from water agency data bases matched with their sampled water well locations. It is not the purpose or intent of this report to describe or interpret the results of these analytical results per se.

A significant amount of scientific research of this aquifer has been conducted by the United States Geological Survey (USGS), et al. Many scientific publications available online and in print describe in great detail the causative factors for the presence of these naturally occurring trace elements in the aquifer, locally, at elevated levels that exceed EPA’s MCLs for public water supplies. The primary objective of this dataset is to disseminate information about groundwater quality trace metal occurrence (arsenic, chromium, selenium and uranium) in the Garber-Wellington to enhance public access and increase awareness to the potential of exposure to these naturally occurring elements in water wells. Historical, laboratory analytical data for samples collected from water wells across the Garber-Wellington Aquifer were obtained from the Oklahoma Department of Environmental Quality (ODEQ), United States Geological Survey (USGS) and the Association of Central Oklahoma Governments (ACOG). Water well metals data that could be associated with a unique earth coordinate (latitude/longitude) were used to create the dataset. Through data review and reduction of the original data sets received, it was determined that 1,835 project wells could be associated with a unique earth coordinate and contained an analytical report for at least one of the 4 primary project metals. For these 1,835 project wells, there are over 4,300 associated laboratory analytical results. *It is important to note that many of the well locations were derived from address locations and legal descriptions, not actual GPS locations. Therefore, this dataset is not intended to be used for site specific applications or matching wells to properties. Due to the variation of well depths, screened zones of wells, and formation variations in the Garber-Wellington aquifer, this dataset should not be used for interpolating values between wells.

The attribute table contains information regarding the source collection agency and the historical maximum concentration level sampled for each metal. Additional fields contain the following three categories for laboratory analytical levels of reporting: (3) Metals data with a concentration that exceeds the maximum contaminant level (MCL); (2) Metals data with a concentration that is less than the MCL (1); Metals data with a concentration that was reported as less than the laboratory detection limit (0) A fourth classification was created to indicate that the well was not sampled for a particular metal. Note: The MCLs of Arsenic, Chromium, Selenium and Uranium are 10, 100, 50, and 30 micrograms/liter respectively.

This project was funded through the 2009 604(b) Water Quality Management Program and the American Recovery and Reinvestment Act of 2009 (ARRA). The OWRB would like to thank the Oklahoma Department of Environmental Quality (ODEQ), the Association of Central Oklahoma Governments (ACOG), and the United States Geological Survey (USGS) for contributing data for this project.For more advanced functionality, open this map with the ArcGIS.com Web Map Viewer.Click here for a map showing the products of a 2013 USGS hydrology study of the Garber-Wellington.

This update (2024) includes the trace elements (metals and metalloids) data from the 6th sampling cycle (2020-2022) of the New Jersey Ambient Groundwater Quality Monitoring Network (AGWQMN). Trace elements are inorganic chemicals that generally occur at concentrations less than 1 mg/L in water. Metals and metalloids are classified as trace elements. They occur naturally in ground water but can also be introduced or mobilized by human activity. The trace elements analyzed for in the Ambient Ground Water Quality Monitoring Network include: Arsenic dissolved as As, Barium dissolved as Ba, Beryllium dissolved as Be, Boron dissolved as B, Cadmium dissolved as Cd, Chromium dissolved as Cr, Copper dissolved as Cu, Iron dissolved as Fe, Lead dissolved as Pb, Manganese dissolved as Mn, Nickel dissolved as Ni, Zinc dissolved as Zn, Antimony dissolved as Sb, and Aluminum dissolved as Al, Selenium dissolved as Se, Mercury dissolved as Hg. Samples were analyzed using United States Geological Survey (USGS) National Water Quality Laboratory (NWQL) Schedule 1622, Trace Elements. Concentrations are reported in micrograms per liter, ug/l. New Jersey's AGWQMN is a cooperative program between the New Jersey Department of Environmental Protection (NJDEP) and United States Geological Survey (USGS). The goals of the current network are to determine the status and trends of shallow groundwater quality as a function of land use related to non-point source pollution in New Jersey. This network consists of 150 monitoring wells screened at the water table. Thirty of these wells were sampled per year on a 5 year cycle from 1999-2013. Beginning with the 4th sampling cycle in 2014, the sampling frequency was changed to once every 3 years (3-year cycle). This layer includes data from sampling cycle 6; samples were collected between 2020 and 2022. The New Jersey Geological and Water Survey (NJGWS) manages the network design, well installation, well maintenance, data interpretation, reporting, and a portion of the well sampling. The NJDEP Bureau of Fresh Water and Biological Monitoring and the United States Geological Survey (USGS) collect the remaining ground-water samples and the USGS National Water Quality Laboratory in Denver, Colorado or their contracted laboratories analyzes them. Chemical and physical parameters analyzed at each well include field parameters such as pH, specific conductance, dissolved oxygen, water temperature and alkalinity, major ions, trace elements (metals), gross-alpha particle activity (radionuclides), volatile organic compounds, nutrients, and pesticides.