This data release provides several data files representing groundwater levels reported through driller's reports for the State of Louisiana Department of Natural Resources (Louisiana Department of Natural Resources, 2023) within or near the Mississippi Alluvial Plain (MAP) and (or) associated with the Mississippi River Valley alluvial aquifer (MRVA). First, a retrieval of data from the State of Louisiana was made and manual preparatory filtering including complete information of location, date, water level (depth below land surface) and water level altitude in feet, and general association with the MAP or MRVA. Further manual and digitally-assisted inspection was made to confirm that the data were not already within the U.S. Geological Survey (USGS) National Water Information System (NWIS) (U.S. Geological Survey, 2023). The agency code for the water levels has been assigned "LA018" (Louisiana Department of Natural Resources) in accordance with the https://help.waterdata.usgs.gov/codes-and-parameters/code/agency_cd_query?fmt=html (accessed February 28, 2023). Use of the LA018 agency code is consistent with historical and current USGS storage practices in NWIS when in collaboration with the State of Louisiana. This first data file is titled "LADNR_drillers_working.csv" (6,374 records). Second, that data file was processed through data structure conversion software (infoGW2visGWDB) (Asquith and Seanor, 2019) and in particular removal of well locations plotting outside the MAP boundary (Painter and Westerman, 2023) was made. The resultant but transient data structure of 4,855 of the original 6,374 records was given over to quality-control and assurance using statistical modeling (visGWDBmrva software) (Asquith and others, 2019, 2020). The statistical analyses result in formation of a regional statistical time series models using generalized additive models (GAMs) and support vector machines (SVMs). Some 18 records by horizontal position having a missing altitude of the bottom of the MRVA and zero records having water-level altitudes below the bottom of the MRVA when digitally working with the Torak and Painter (2019) surface of the MRVA bottom. These 18 records are retained through the workflow described herein to avoid potential scientific interpretation of hydrogeologic framework. In summary, for each of the 4,855 well-water-level records (or rather in detail, each unique well identifier), the visGWDBmrva software isolated all water levels for the MAP/MRVA from USGS (2023) within 16 kilometers radial distance. This means that the driller's dataset is being internally compared to itself and USGS MAP/MRVA data. The visGWDBmrva software computed a "pseudo water level" from a blending of GAM and SVM model predictions for the date of the driller's recorded water level. These computations are all created on-the-fly. A residual was computed from the pseudo water level (as altitude) to that water-level altitude reported for the well-water-level record of the driller's dataset. These statistical results are listed the file titled "LADNR_retained_levels.csv" (4,744 records) for which records were retained LADNR_drillers_working.csv if the absolute value of the residual of the well-water-level record and the pseudo water level was less than or equal to 20 feet. This threshold resulted from exploratory review of the statistical computations and is consistent with Smith and others (2020) and Weber and others (2021) for a similar driller's reported dataset for the Missouri part of the MAP/MRVA. The results listed in file LADNR_retained_levels.csv are deemed especially suitable for greater statistical modeling of groundwater levels in the MRVA (Asquith and Killian, 2022).

This data release provides several data files representing groundwater levels reported through driller's reports for the State of Louisiana Department of Natural Resources (Louisiana Department of Natural Resources, 2023) within or near the Mississippi Alluvial Plain (MAP) and (or) associated with the Mississippi River Valley alluvial aquifer (MRVA). First, a retrieval of data from the State of Louisiana was made and manual preparatory filtering including complete information of location, date, water level (depth below land surface) and water level altitude in feet, and general association with the MAP or MRVA. Further manual and digitally-assisted inspection was made to confirm that the data were not already within the U.S. Geological Survey (USGS) National Water Information System (NWIS) (U.S. Geological Survey, 2023). The agency code for the water levels has been assigned "LA018" (Louisiana Department of Natural Resources) in accordance with the https://help.waterdata.usgs.gov/codes-and-parameters/code/agency_cd_query?fmt=html (accessed February 28, 2023). Use of the LA018 agency code is consistent with historical and current USGS storage practices in NWIS when in collaboration with the State of Louisiana. This first data file is titled "LADNR_drillers_working.csv" (6,374 records). Second, that data file was processed through data structure conversion software (infoGW2visGWDB) (Asquith and Seanor, 2019) and in particular removal of well locations plotting outside the MAP boundary (Painter and Westerman, 2023) was made. The resultant but transient data structure of 4,855 of the original 6,374 records was given over to quality-control and assurance using statistical modeling (visGWDBmrva software) (Asquith and others, 2019, 2020). The statistical analyses result in formation of a regional statistical time series models using generalized additive models (GAMs) and support vector machines (SVMs). Some 18 records by horizontal position having a missing altitude of the bottom of the MRVA and zero records having water-level altitudes below the bottom of the MRVA when digitally working with the Torak and Painter (2019) surface of the MRVA bottom. These 18 records are retained through the workflow described herein to avoid potential scientific interpretation of hydrogeologic framework. In summary, for each of the 4,855 well-water-level records (or rather in detail, each unique well identifier), the visGWDBmrva software isolated all water levels for the MAP/MRVA from USGS (2023) within 16 kilometers radial distance. This means that the driller's dataset is being internally compared to itself and USGS MAP/MRVA data. The visGWDBmrva software computed a "pseudo water level" from a blending of GAM and SVM model predictions for the date of the driller's recorded water level. These computations are all created on-the-fly. A residual was computed from the pseudo water level (as altitude) to that water-level altitude reported for the well-water-level record of the driller's dataset. These statistical results are listed the file titled "LADNR_retained_levels.csv" (4,744 records) for which records were retained LADNR_drillers_working.csv if the absolute value of the residual of the well-water-level record and the pseudo water level was less than or equal to 20 feet. This threshold resulted from exploratory review of the statistical computations and is consistent with Smith and others (2020) and Weber and others (2021) for a similar driller's reported dataset for the Missouri part of the MAP/MRVA. The results listed in file LADNR_retained_levels.csv are deemed especially suitable for greater statistical modeling of groundwater levels in the MRVA (Asquith and Killian, 2022).

An objective review (Asquith and others, 2018 and 2020) of the distribution of the first two significant figures of a water-level measurement (depth below land surface) was done on the 10,295 measurements (one per well) that met the threshold criteria. The purpose of this review was to ascertain the degree to which substantial rounding of values might exist in the dataset. It was evident that the dataset has a large number of values rounded to the nearest integer foot with a tendency for more rounding towards even integers. For values between 10 and 99 feet, there is a large number of values rounded to the even 10 feet and for values less than about 35 feet, there are an excessive number of values rounded the nearest. There are also numerous values of 12 and 14. This suggests that considerable estimation or rounding of water levels have been made probably by use of apparatus other than graduate tapes. Systematic review of original data sources is not possible and insufficient metadata exist for a manual of each value in the data set. However, the database is large and offers an opportunity for data mining and machine learning to foster further review. A large, objective, technically-demanding, and rigorous spatial-temporal review of the water-level data, expressed in altitude, was made for the 10,295 water level records comprising this data release.

An objective review (Asquith and others, 2018 and 2020) of the distribution of the first two significant figures of a water-level measurement (depth below land surface) was done on the 10,295 measurements (one per well) that met the threshold criteria. The purpose of this review was to ascertain the degree to which substantial rounding of values might exist in the dataset. It was evident that the dataset has a large number of values rounded to the nearest integer foot with a tendency for more rounding towards even integers. For values between 10 and 99 feet, there is a large number of values rounded to the even 10 feet and for values less than about 35 feet, there are an excessive number of values rounded the nearest. There are also numerous values of 12 and 14. This suggests that considerable estimation or rounding of water levels have been made probably by use of apparatus other than graduate tapes. Systematic review of original data sources is not possible and insufficient metadata exist for a manual of each value in the data set. However, the database is large and offers an opportunity for data mining and machine learning to foster further review. A large, objective, technically-demanding, and rigorous spatial-temporal review of the water-level data, expressed in altitude, was made for the 10,295 water level records comprising this data release.

The Missouri Department of Natural Resources’ (MoDNR) Well Information Management System (WIMS) is a repository for well information that includes date of completion, well construction, geology, and water level. Well information is provided by the water well drillers during the permitting process and is updated periodically by MoDNR. Well information is available in WIMS as early as 1983 to the present. This data set consists of 16,639 well records extracted from WIMS that were likely drilled into the Mississippi River Valley alluvial aquifer in Missouri. Records that may not reflect the true groundwater conditions in the aquifer were identified using a series of criteria described in detail below. The threshold criteria are described in detail in the “entity and attribute” section.

A potentiometric-surface map represents the altitude at which water would stand in tightly cased wells completed at any location within the study area aquifer. Using the altitude of water levels measured in the study area, the potentiometric-surface map depicts points of equal altitude with contours denoting a given water-level altitude calculated by subtracting the water level measured from the land-surface elevation (National Geodetic Vertical Datum of 1929). The contour lines were created using computer-based program ArcGIS with an interval of 10 feet. The direction of water flow from areas of high elevation to low elevation can be interpreted using potentiometric-surface maps and areas of decreased groundwater levels can be identified. The 2014 potentiometric-surface map shows ten total cones of depressions: two large depressions, five small depressions, and three areas of decreased water levels. As with the 2010 potentiometric-surface map, one large depression begins in southeastern Arkansas County, near the Arkansas and Desha County line, and extends north into Prairie County, west into Lonoke County, and east into the western-most part of Monroe County. Even though the center of the depression had deepened in 2010, the area of the cone in Arkansas County within the southeastern half of the depression had not expanded horizontally. The analysis of the 2014 potentiometric-surface map suggests no horizontal expansion in this area. The additional GIS shapefiles were used to depicts the western extent of the Mississippi River alluvial aquifer in eastern Arkansas on plates 1, 2, and 3 in Rodgers and Whaling (2020).

This dataset contains groundwater (GW)-altitude (ALT) data from wells that was used or considered to create a potentiometric-surface map for the Mississippi River Valley alluvial (MRVA) aquifer for spring 2018. The groundwater-altitude data was referenced to the North American Vertical Datum of 1988 (NAVD 88). Most of the wells were measured annually, but some wells were measured more than one time in a year and a small number of wells were measured continuously. Groundwater-altitude data were from wells measured in spring 2018. Spring-time measurements were preferred because water levels had generally recovered from pumping during the previous irrigation season and it was before pumping began for the current irrigation season. To best reflect hydrologic conditions in the MRVA aquifer, the groundwater altitudes used to create the 2018 potentiometric surface would be measured in a short-time frame of days or a week and there would be available data (for example from sets of wells with short-screen (about 5 to 10 feet or 1.5 to 3 meters) installed near the top, in the middle, and near the bottom of the aquifer) to indicate vertical flow components. However, most wells screened in the MRVA aquifer were measured before the potentiometric-surface map of the MRVA aquifer was planned and therefore the timing of each well’s measurement(s) was determined by the needs and schedules of the entities doing the measurements. Also, many of the measured wells had longer screens (from greater than 10 feet or 3 meters and covering a substantial part of the aquifer thickness), therefore their water-level measurements represent an average head in the aquifer for that location. The resultant potentiometric-surface contours and raster represents the generalized central tendency for spring 2018, but it would not be useful for some purposes, such as for calibration of a groundwater-flow model for early April 2018 or for some local scale assessments.

This dataset contains groundwater (GW)-altitude (ALT) data from wells that was used or considered to create a potentiometric-surface map for the Mississippi River Valley alluvial (MRVA) aquifer for spring 2018. The groundwater-altitude data was referenced to the North American Vertical Datum of 1988 (NAVD 88). Most of the wells were measured annually, but some wells were measured more than one time in a year and a small number of wells were measured continuously. Groundwater-altitude data were from wells measured in spring 2018. Spring-time measurements were preferred because water levels had generally recovered from pumping during the previous irrigation season and it was before pumping began for the current irrigation season. To best reflect hydrologic conditions in the MRVA aquifer, the groundwater altitudes used to create the 2018 potentiometric surface would be measured in a short-time frame of days or a week and there would be available data (for example from sets of wells with short-screen (about 5 to 10 feet or 1.5 to 3 meters) installed near the top, in the middle, and near the bottom of the aquifer) to indicate vertical flow components. However, most wells screened in the MRVA aquifer were measured before the potentiometric-surface map of the MRVA aquifer was planned and therefore the timing of each well’s measurement(s) was determined by the needs and schedules of the entities doing the measurements. Also, many of the measured wells had longer screens (from greater than 10 feet or 3 meters and covering a substantial part of the aquifer thickness), therefore their water-level measurements represent an average head in the aquifer for that location. The resultant potentiometric-surface contours and raster represents the generalized central tendency for spring 2018, but it would not be useful for some purposes, such as for calibration of a groundwater-flow model for early April 2018 or for some local scale assessments.

A potentiometric surface map for spring 2016 was created for the Mississippi River Valley alluvial (MRVA) aquifer, which was referenced to the North American Vertical Datum of 1988 (NAVD 88), using most of the available groundwater-altitude data from wells and surface-water-altitude data from streamgages. Most of the wells were measured annually or one time, after installation, but some wells were measured more than one time in a year and a small number of wells were measured continually. Streamgages were typically operated continuously. The potentiometric surface map for 2016 was created as part of the U.S. Geological Survey (USGS) Water Availability and Use Science Program to support investigations that characterize the MRVA aquifer. The potentiometric contours ranged from 10 feet to 340 feet above NAVD 88. The regional direction of groundwater flow was generally towards the south-southwest, except in areas of groundwater-altitude depressions, where groundwater flows into the depressions, and near rivers, where groundwater flow generally parallels the flow in the rivers. There are large depressions in the potentiometric surface in the lower half of the Cache region and in most of the Grand Prairie and Delta regions.

The Ogallala aquifer is contained in the Tertiary-age Ogallala Formation in the Texas Panhandle and is the primary water-bearing hydrogeologic unit of the High Plains aquifer system. The Ogallala aquifer is the primary source of water used for agricultural and municipal purposes in the Texas Panhandle. The Dockum aquifer is contained in the formations that compose the Triassic-age Dockum Group and serves as an additional source of water in the Texas Panhandle. Depth to groundwater measurements and water-quality samples were collected from 32 monitoring wells in the North Plains Groundwater Conservation District management area within the northern part of the Texas Panhandle as part of two synoptic sampling efforts, one during 2012–13 and the other during 2019–20. Groundwater-quality samples were collected for analysis of dissolved solids, major ions, nutrients, and trace elements. Selected organic compounds were analyzed in samples collected from a subset of 6 wells. Sample results for selected constituents were compared to drinking-water standards and between the two synoptic sampling times in an interpretative report. A previously published report by Baldys and others (2014) discusses the results from the 2012–13 sampling event.