The upper portion of the Troublesome Aquifer is the sole source of water for domestic use in the Greater Pole Creek Basin, situated in the western portion of the upper Fraser River Valley in Grand County, Colorado. Data from drilling records for wells installed near and within recent home developments, municipal water-suppliers, water-quality records, and published reports are summarized as an initial synthesis of aquifer water quantity and quality. In spite of persistent drought and increased domestic aquifer-water usage, aquifer water storage remains robust with water levels little changed during the past 25 years. Water-quality data indicate substantial variability with depth beneath the top of the aquifer. Data from wells completed in the overlying shallow alluvial aquifer are also presented for comparison. This document constitutes a new baseline for assessment of current and future groundwater resources within this portion of the upper Fraser River valley. Suggested future investigations include water-table monitoring and comprehensive water-quality surveys for water derived from wells completed in the Troublesome Aquifer.

This data set represents the extent of the Wyoming Tertiary aquifers in Wyoming.

This data set represents the extent of the Wyoming Tertiary aquifers in Wyoming.

Dataset contains the groundwater well locations and water-level measurements for 37 wells measured during the water-level survey of the Wilcox aquifer in Arkansas, April 2015 to June 2015. Well-location and water-level data are publicly available from the U.S. Geological Survey's National Water Information System.

Groundwater age distribution and susceptibility to natural and anthropogenic contaminants were assessed for selected principal aquifers of the Western United States: the Central Valley aquifer system (CVAL), the Basin and Range basin-fill aquifers (BNRF), the Rio Grande aquifer system (RIOG), the High Plains aquifer (HPAQ), the Columbia Plateau basaltic-rock aquifers (CLPT), and the Colorado Plateaus aquifers (COPL). Groundwater ages were estimated by calibration of environmental tracers (tritium, tritiogenic helium-3, chlorofluorocarbons, sulfur hexafluoride, carbon-14 and radiogenic helium-4) to lumped parameter models (LPMs) for 1,353 samples from 1,182 sample locations. Groundwater samples were collected from wells (mainly drinking-water) in the CVAL between 2004 and 2018 as part of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment Priority Basin Project (GAMA-PBP) and the National Water-Quality Assessment (NAWQA) Project; and in the BNRF in 2013, the RIOG in 2014 and 2015, the HPAQ between 2014 and 2017, the CPLT in 2016, and the COPL in 2017 as part of NAWQA. Table 1 reports the primary results of this assessment and it contains condensed results from dissolved gas modeling and calculated environmental tracer concentrations; results of the tritium age classification, susceptibility index, and mean groundwater age of each sample in this assessment; and water level and well construction information for some wells. Calibrated lumped parameter models provide the optimal mean age and mixing parameter(s) used to compute the distribution of ages that explain the measured tracer concentrations in a sample. Tables 2 and 3 provide results in support of Table 1. Table 2 reports detailed results for the calibration of dissolved gas models to neon, argon, krypton, xenon, and nitrogen. Calibrated dissolved gas models provide the optimal water temperature, excess air, entrapped air, fractionation of gases, and excess nitrogen gas (mainly from denitrification) that explain the measured dissolved gases in a sample. Table 3 reports measured concentrations and the detailed calculations of environmental tracer concentrations derived from the dissolved gas modeling results in Table 2. Calculated concentrations of environmental tracers that can be used in groundwater age calculations are the dry air mixing ratio of sulfur hexafluoride or chlorofluorocarbons, tritiogenic helium-3, which is the concentration of helium-3 from the decay of tritium, and radiogenic helium-4, which is the amount of helium generated from the decay of uranium and thorium in aquifer sediments. In addition to these three tables, two ancillary tables are included to provide more detailed information about the fields and the abbreviations used in tables 1-3.

Groundwater age distribution and susceptibility to natural and anthropogenic contaminants were assessed for selected principal aquifers of the Western United States: the Central Valley aquifer system (CVAL), the Basin and Range basin-fill aquifers (BNRF), the Rio Grande aquifer system (RIOG), the High Plains aquifer (HPAQ), the Columbia Plateau basaltic-rock aquifers (CLPT), and the Colorado Plateaus aquifers (COPL). Groundwater ages were estimated by calibration of environmental tracers (tritium, tritiogenic helium-3, chlorofluorocarbons, sulfur hexafluoride, carbon-14 and radiogenic helium-4) to lumped parameter models (LPMs) for 1,353 samples from 1,182 sample locations. Groundwater samples were collected from wells (mainly drinking-water) in the CVAL between 2004 and 2018 as part of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment Priority Basin Project (GAMA-PBP) and the National Water-Quality Assessment (NAWQA) Project; and in the BNRF in 2013, the RIOG in 2014 and 2015, the HPAQ between 2014 and 2017, the CPLT in 2016, and the COPL in 2017 as part of NAWQA. Table 1 reports the primary results of this assessment and it contains condensed results from dissolved gas modeling and calculated environmental tracer concentrations; results of the tritium age classification, susceptibility index, and mean groundwater age of each sample in this assessment; and water level and well construction information for some wells. Calibrated lumped parameter models provide the optimal mean age and mixing parameter(s) used to compute the distribution of ages that explain the measured tracer concentrations in a sample. Tables 2 and 3 provide results in support of Table 1. Table 2 reports detailed results for the calibration of dissolved gas models to neon, argon, krypton, xenon, and nitrogen. Calibrated dissolved gas models provide the optimal water temperature, excess air, entrapped air, fractionation of gases, and excess nitrogen gas (mainly from denitrification) that explain the measured dissolved gases in a sample. Table 3 reports measured concentrations and the detailed calculations of environmental tracer concentrations derived from the dissolved gas modeling results in Table 2. Calculated concentrations of environmental tracers that can be used in groundwater age calculations are the dry air mixing ratio of sulfur hexafluoride or chlorofluorocarbons, tritiogenic helium-3, which is the concentration of helium-3 from the decay of tritium, and radiogenic helium-4, which is the amount of helium generated from the decay of uranium and thorium in aquifer sediments. In addition to these three tables, two ancillary tables are included to provide more detailed information about the fields and the abbreviations used in tables 1-3.

This data set consists of digital water-level-change contour for the High Plains aquifer in the Central United States, 1980 to 1994. The High Plains aquifer extends from south of 32 degrees to almost 44 degrees north latitude and from 96 degrees 30 minutes to 104 degrees west longitude. The aquifer underlies about 174,000 square miles in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. This digital data set was created from 6,143 wells measured in both 1980 and 1994. The water-level-change contours were drawn manually on mylar. The contours were converted into a digital map at a scale of 1:1,250,000. The data should not be used at scales larger than 1:1,250,000.

This data set consists of digital water-level-change contour for the High Plains aquifer in the Central United States, 1980 to 1994. The High Plains aquifer extends from south of 32 degrees to almost 44 degrees north latitude and from 96 degrees 30 minutes to 104 degrees west longitude. The aquifer underlies about 174,000 square miles in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. This digital data set was created from 6,143 wells measured in both 1980 and 1994. The water-level-change contours were drawn manually on mylar. The contours were converted into a digital map at a scale of 1:1,250,000. The data should not be used at scales larger than 1:1,250,000.

The High Plains aquifer extends from about 32 degrees to almost 44 degrees north latitude and from about 96 degrees 30 minutes to 106 degrees west longitude. The aquifer underlies about 175,000 square miles in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. This digital dataset consists of three sets of water-level measurements. The first set are the supplemental water-level measurements for 547 wells screened in the High Plains aquifer, not located in New Mexico, measured in predevelopment and at least once for 2015 through 2018, but not for 2019. These supplemental measurements were used to calculate historical water-level change values for predevelopment to 2015 to 2018 and approximate water-level change values from predevelopment to 2019 to substantiate the map of water-level changes, predevelopment (about 1950) to 2019 (figure 1 in https://doi.org/10.3133/sir20235143). The water-level measurements used to calculate historical water-level changes from predevelopment are (1) 218 wells measured in predevelopment and in 2018, but not measured in 2019, which are used to calculate water-level change, predevelopment to 2018, (2) 152 wells measured in predevelopment and in 2017, but not measured in 2018 or 2019, which are used to calculate water-level change, predevelopment to 2017, (3) 117 wells measured in predevelopment and in 2016, but not measured in 2017, 2018, or 2019, which are used to calculate water-level change, predevelopment to 2016, and (4) 60 wells measured in predevelopment and in 2015, but not measured in 2016, 2017, 2018, or 2019, which are used to calculate water-level change, predevelopment to 2015. The second and third sets of water-level measurements were used to approximate water-level change, predevelopment to 2019, but did not have predevelopment water-level measurements. The second set included 292 wells, which were located in areas where water level declines from predevelopment to 1980 were 50 feet or more (Luckey and others, 1981; Cederstrand and Becker, 1999) and were measured in 1980 and in 2019, but not measured in the predevelopment period. For these wells, approximate water-level changes, predevelopment to 2019, were calculated as the starting value of the polygon range (for example 50 ft for the polygon of declines from 50 to 75 ft) from the map of water-level change, predevelopment to 1980, plus measured water-level change from 1980 to 2019. The third set of water-level measurements used to calculate approximate water-level changes were from 1,213 wells that were measured on or before 6/15/1978 (termed post-development) and in 2019, but not in the predevelopment period. For these wells, approximate water-level changes, predevelopment to 2019, were calculated as the water level, 2019, minus water level, post-development.

The High Plains aquifer extends from about 32 degrees to almost 44 degrees north latitude and from about 96 degrees 30 minutes to 106 degrees west longitude. The aquifer underlies about 175,000 square miles in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. This digital dataset consists of three sets of water-level measurements. The first set are the supplemental water-level measurements for 547 wells screened in the High Plains aquifer, not located in New Mexico, measured in predevelopment and at least once for 2015 through 2018, but not for 2019. These supplemental measurements were used to calculate historical water-level change values for predevelopment to 2015 to 2018 and approximate water-level change values from predevelopment to 2019 to substantiate the map of water-level changes, predevelopment (about 1950) to 2019 (figure 1 in https://doi.org/10.3133/sir20235143). The water-level measurements used to calculate historical water-level changes from predevelopment are (1) 218 wells measured in predevelopment and in 2018, but not measured in 2019, which are used to calculate water-level change, predevelopment to 2018, (2) 152 wells measured in predevelopment and in 2017, but not measured in 2018 or 2019, which are used to calculate water-level change, predevelopment to 2017, (3) 117 wells measured in predevelopment and in 2016, but not measured in 2017, 2018, or 2019, which are used to calculate water-level change, predevelopment to 2016, and (4) 60 wells measured in predevelopment and in 2015, but not measured in 2016, 2017, 2018, or 2019, which are used to calculate water-level change, predevelopment to 2015. The second and third sets of water-level measurements were used to approximate water-level change, predevelopment to 2019, but did not have predevelopment water-level measurements. The second set included 292 wells, which were located in areas where water level declines from predevelopment to 1980 were 50 feet or more (Luckey and others, 1981; Cederstrand and Becker, 1999) and were measured in 1980 and in 2019, but not measured in the predevelopment period. For these wells, approximate water-level changes, predevelopment to 2019, were calculated as the starting value of the polygon range (for example 50 ft for the polygon of declines from 50 to 75 ft) from the map of water-level change, predevelopment to 1980, plus measured water-level change from 1980 to 2019. The third set of water-level measurements used to calculate approximate water-level changes were from 1,213 wells that were measured on or before 6/15/1978 (termed post-development) and in 2019, but not in the predevelopment period. For these wells, approximate water-level changes, predevelopment to 2019, were calculated as the water level, 2019, minus water level, post-development.