During the spring and summer of 2020, the U.S. Geological Survey, Lower Mississippi – Gulf Water Science Center, conducted single well slug tests on selected wells within the Mississippi Alluvial Plain of Arkansas and Mississippi to estimate hydraulic conductivity (K) and transmissivity (T) values for the aquifers in which the wells are screened. A total of 324 test were conducted on 48 wells. The computer software AQTESOLV for Windows (Duffield, 2007) was used to interpretate the slug test data to estimate K and T values. Mean estimates of K for the 44 wells completed in the Mississippi River Valley alluvial aquifer ranged from 3 to 401 feet per day (ft/day) and mean estimates of T ranged from 285 to 80,559 square feet per day (ft2/day). Mean estimates of K for the 4 wells completed in the Sparta Sand or 500-foot Sand (Memphis Aquifer) that make up part of the middle Claiborne aquifer of the Mississippi embayment aquifer system ranged from 0.14 to 183 ft/day and mean estimates of T ranged from 55 to 67,913 ft2/day. This Data Release contains the following data and supporting metadata: 1. A PDF document with calibration information for the mechanical slugs used for testing. 2. A zipped file of the 48-site files folders containing: 1. The site’s slug test field form (pdf). 2. Digital images of the site (jpg). 3. Water-level pressure transducer log files (csv), 4. Excel files(s) of transducer data with Time vs. Water Depth plots and the selected Time – Displacement data used for analysis. 5. The AQTESOLV solution report files (aqt) for each slug test. 3. A summary data file in two formats (csv & GIS shape file) including the following information for each site: 1. Site information [site name, agency code, USGS National Water Information System (NWIS) site number] 2. Location information (latitude, longitude, state, county). 3. Well construction information [well depth and diameter, casing diameter, top and bottom of opening (screen), and opening (screen) length]. 4. Aquifer information (local and national aquifer codes, and aquifer thickness). 5. Slug test information (test date and static water-level). 6. Estimates information (minimum, mean, median, and maximum K and T values and the solution method). 4. An equipment documentation file (csv) listing the water-level tape, transducer, and slug used at each site. 5. A water-level documentation file (csv) listing the before and after testing water-level measurements for each site. 6. A model input file (csv) listing the values input into the model for each test. 7. A model solutions file (csv) listing both the “Visual” and “Auto” match solution estimates for the slug tests at each site. Additional information, including discussions of the hydrogeologic setting, well descriptions, slug testing and analysis methods, and a summary of the slug test results are available in the Open File Report associated with this Data Release (Pugh, 2021). This dataset was collected and analyzed as part of the U.S. Geological Survey, Mississippi Alluvial Plain Regional Water-Availability Study.

The Mississippi River Valley alluvial aquifer (“alluvial aquifer”) is one of the most extensively developed aquifers in the United States. The alluvial aquifer is present at the land surface in parts of southeastern Missouri, northeastern Louisiana, western Mississippi, western Tennessee and Kentucky near the Mississippi River, and throughout eastern Arkansas. Historical (1940–2006) and recent (2019–20) aquifer-test datasets were compiled to model transmissivity and hydraulic conductivity of the alluvial aquifer from recent (2018–19) airborne electromagnetic (AEM) survey data. This data release contains the aquifer-test and geophysical data along with computer codes written in Matlab version R2014a syntax used to process the data as described in the corresponding journal article (Ikard and others, 2022). The computer codes were designed to use the datasets contained in comma-separated values (.csv) and ASCII text (.txt) files to: (1) calculate the longitudinal conductance, transverse resistance, and mean electric resistivity frameworks of the alluvial aquifer to depths of 125 meters within the Mississippi Alluvial Plain (MAP) physiographic province from the electric resistivity framework mapped by frequency-domain airborne electromagnetic (AEM) induction surveying along 16,816 line-kilometers (km) of flight path covering 95,000 square-kilometers (km2) of the MAP, (2) correlate the mean electric resistivity at discrete points within the MAP to a database of 160 spatially distributed historical values of alluvial-aquifer transmissivity, quantified by aquifer tests performed in the MAP between 1940 and 2006, and (3) apply user-defined log-linear electric–hydraulic (e–h) relations, defined from the correlation data produced in (2), to 2,364 line-kilometers of separate high-resolution AEM resistivity data covering the 1,000 km2 Shellmound, Mississippi study area (“Shellmound grid”) to calculate alluvial-aquifer transmissivity and hydraulic conductivity where aquifer test data are sparse. The datasets contained herein were extracted from larger parent datasets that are published in a series of U.S. Geological Survey data releases and Scientific Investigation Reports to support the Hydrogeologic Framework component of the MAP Regional Water Availability Study, and citations and web-links to each parent dataset are provided in the metadata record.

The Mississippi River Valley alluvial aquifer (“alluvial aquifer”) is one of the most extensively developed aquifers in the United States. The alluvial aquifer is present at the land surface in parts of southeastern Missouri, northeastern Louisiana, western Mississippi, western Tennessee and Kentucky near the Mississippi River, and throughout eastern Arkansas. Historical (1940–2006) and recent (2019–20) aquifer-test datasets were compiled to model transmissivity and hydraulic conductivity of the alluvial aquifer from recent (2018–19) airborne electromagnetic (AEM) survey data. This data release contains the aquifer-test and geophysical data along with computer codes written in Matlab version R2014a syntax used to process the data as described in the corresponding journal article (Ikard and others, 2022). The computer codes were designed to use the datasets contained in comma-separated values (.csv) and ASCII text (.txt) files to: (1) calculate the longitudinal conductance, transverse resistance, and mean electric resistivity frameworks of the alluvial aquifer to depths of 125 meters within the Mississippi Alluvial Plain (MAP) physiographic province from the electric resistivity framework mapped by frequency-domain airborne electromagnetic (AEM) induction surveying along 16,816 line-kilometers (km) of flight path covering 95,000 square-kilometers (km2) of the MAP, (2) correlate the mean electric resistivity at discrete points within the MAP to a database of 160 spatially distributed historical values of alluvial-aquifer transmissivity, quantified by aquifer tests performed in the MAP between 1940 and 2006, and (3) apply user-defined log-linear electric–hydraulic (e–h) relations, defined from the correlation data produced in (2), to 2,364 line-kilometers of separate high-resolution AEM resistivity data covering the 1,000 km2 Shellmound, Mississippi study area (“Shellmound grid”) to calculate alluvial-aquifer transmissivity and hydraulic conductivity where aquifer test data are sparse. The datasets contained herein were extracted from larger parent datasets that are published in a series of U.S. Geological Survey data releases and Scientific Investigation Reports to support the Hydrogeologic Framework component of the MAP Regional Water Availability Study, and citations and web-links to each parent dataset are provided in the metadata record.

Since the 1940's, hydrologists have used aquifer tests to estimate the hydrogeologic properties near test wells. Results from these tests are recorded in various files, databases, reports and scientific publications. The U.S. Geological Survey (USGS), Lower Mississippi-Gulf Water Science Center (LMG) is aggregating all aquifer test results from Alabama, Arkansas, Louisiana, Mississippi and Tennessee into a single dataset that is publicly available in a machine-readable format. This dataset contains information and results from 2,245 aquifer tests compiled for aquifers located in the LMG-Hydrogeologic Aquifer Test Dataset - December 2020. Descriptive statistics for the December 2020 dataset are presented in Table 1 (below) and in the Summary_Readme.pdf. Additionally, this dataset contains 6 attribute tables (.txt files) with additional information for various fields, a zip file containing the geospatial data, and the companion attribute table as a .txt file. THE LMG-HYDROGEOLOGIC AQUIFER TEST DATASET – DECEMBER 2020 IS AVAILABLE IN TWO FORMATS: 1) a tab delimited text (.txt) UTF-8 file and 2) an ESRI GIS point shapefile. FIELDS INCLUDED IN THE LMG-HYDROGEOLOGIC AQUIFER TEST DATASET – DECEMBER 2020: [a complete list of field names, their definitions and units are listed in the Summary_Readme.pdf file] Location data: USGS site identification number, local identification name, Public Land Survey System number, latitude, longitude, State and county. Well construction data: Construction date, well depth, Diameter of well, diameter of casing, depth to top of opening (screen) interval, depth to bottom of opening interval and length of the open interval. Aquifer data: Local aquifer name and code, national aquifer name and code, top of aquifer (altitude), bottom of aquifer, and thickness of aquifer. Groundwater test data: Test date, yield/discharge, length of time associated with yield, static water-level in feet below land surface, production water-level in feet below land surface associated with yield, drawdown associated with yield. Hydrogeologic data: Specific capacity, transmissivity, horizontal Conductivity, vertical conductivity, permeability and storage coefficient. Ancillary data: Method of test analysis and data source reference. DESCRIPTIONS OF ATTACHED FILES: Summary_Readme.pdf: a Portable Document Format (PDF) file with field names, definitions and units for the aquifer test dataset and the associated attribute tables. This file also contains summary statistics for aquifer test compiled through December 2020. LMG-HydrogeologicAqfrTestDataset_Dec2020.txt: a tab-delimited, UTF-8 text file of the attribute table associated with the LMG-HydrogeologicTestData_Dec2020 geospatial dataset. AtbtTbl_AqfrCd_Readme.txt: an UTF-8 text file containing information from the National Water Information System: Help System web page about USGS groundwater codes. (accessed December 4, 2019 at https://help.waterdata.usgs.gov/codes-and-parameters) AtbtTbl_FipsGeographyCodes.txt: a tab-delimited, UTF-8 text file of FIPS (Federal Information Processing Standards) codes, uniquely identifying States, counties and county equivalents in the United States. Note: to reduce the size of this file, city codes were removed. (accessed January 8, 2020 at https://www.census.gov/geographies/reference-files/2017/demo/popest/2017-fips.html). AtbtTbl_LocalAqfrCodes.txt: a tab-delimited, UTF-8 text file of eight-character string identifying an aquifer. Codes are defined by the "Catalog of Aquifer Names and Geologic Unit Codes used by the USGS. (accessed December 4, 2019 at https://help.waterdata.usgs.gov/aqfr_cd) AtbtTbl_NatAqfrCodes.txt: a tab-delimited, UTF-8 text file of ten-character strings identifying a National aquifer, or principal aquifer of the United States, that are defined as regionally extensive aquifers or aquifer systems that have the potential to be used as a source of potable water. (accessed December 4, 2019 at

Since the 1940's, hydrologists have used aquifer tests to estimate the hydrogeologic properties near test wells. Results from these tests are recorded in various files, databases, reports and scientific publications. The U.S. Geological Survey (USGS), Lower Mississippi-Gulf Water Science Center (LMG) is aggregating all aquifer test results from Alabama, Arkansas, Louisiana, Mississippi and Tennessee into a single dataset that is publicly available in a machine-readable format. This dataset contains information and results from 2,245 aquifer tests compiled for aquifers located in the LMG-Hydrogeologic Aquifer Test Dataset - December 2020. Descriptive statistics for the December 2020 dataset are presented in Table 1 (below) and in the Summary_Readme.pdf. Additionally, this dataset contains 6 attribute tables (.txt files) with additional information for various fields, a zip file containing the geospatial data, and the companion attribute table as a .txt file. THE LMG-HYDROGEOLOGIC AQUIFER TEST DATASET – DECEMBER 2020 IS AVAILABLE IN TWO FORMATS: 1) a tab delimited text (.txt) UTF-8 file and 2) an ESRI GIS point shapefile. FIELDS INCLUDED IN THE LMG-HYDROGEOLOGIC AQUIFER TEST DATASET – DECEMBER 2020: [a complete list of field names, their definitions and units are listed in the Summary_Readme.pdf file] Location data: USGS site identification number, local identification name, Public Land Survey System number, latitude, longitude, State and county. Well construction data: Construction date, well depth, Diameter of well, diameter of casing, depth to top of opening (screen) interval, depth to bottom of opening interval and length of the open interval. Aquifer data: Local aquifer name and code, national aquifer name and code, top of aquifer (altitude), bottom of aquifer, and thickness of aquifer. Groundwater test data: Test date, yield/discharge, length of time associated with yield, static water-level in feet below land surface, production water-level in feet below land surface associated with yield, drawdown associated with yield. Hydrogeologic data: Specific capacity, transmissivity, horizontal Conductivity, vertical conductivity, permeability and storage coefficient. Ancillary data: Method of test analysis and data source reference. DESCRIPTIONS OF ATTACHED FILES: Summary_Readme.pdf: a Portable Document Format (PDF) file with field names, definitions and units for the aquifer test dataset and the associated attribute tables. This file also contains summary statistics for aquifer test compiled through December 2020. LMG-HydrogeologicAqfrTestDataset_Dec2020.txt: a tab-delimited, UTF-8 text file of the attribute table associated with the LMG-HydrogeologicTestData_Dec2020 geospatial dataset. AtbtTbl_AqfrCd_Readme.txt: an UTF-8 text file containing information from the National Water Information System: Help System web page about USGS groundwater codes. (accessed December 4, 2019 at https://help.waterdata.usgs.gov/codes-and-parameters) AtbtTbl_FipsGeographyCodes.txt: a tab-delimited, UTF-8 text file of FIPS (Federal Information Processing Standards) codes, uniquely identifying States, counties and county equivalents in the United States. Note: to reduce the size of this file, city codes were removed. (accessed January 8, 2020 at https://www.census.gov/geographies/reference-files/2017/demo/popest/2017-fips.html). AtbtTbl_LocalAqfrCodes.txt: a tab-delimited, UTF-8 text file of eight-character string identifying an aquifer. Codes are defined by the "Catalog of Aquifer Names and Geologic Unit Codes used by the USGS. (accessed December 4, 2019 at https://help.waterdata.usgs.gov/aqfr_cd) AtbtTbl_NatAqfrCodes.txt: a tab-delimited, UTF-8 text file of ten-character strings identifying a National aquifer, or principal aquifer of the United States, that are defined as regionally extensive aquifers or aquifer systems that have the potential to be used as a source of potable water. (accessed December 4, 2019 at

A water-supply plan is being developed for Wake County, North Carolina, in accordance with the 50-year planning window used by the North Carolina Division of Water Resources for residents in unincorporated areas of the county. To develop this supply plan, Wake County seeks to better understand the sustainability of groundwater resources of the regolith/fractured-rock aquifer system. Slug tests were performed in 17 wells in the Wake County area, during 2020 and 2021, to provide values of horizontal hydraulic conductivity and transmissivity to support the development of Wake County’s water-supply plan. Wake County is in the Piedmont physiographic province. The two principal aquifers are nonconsolidated regolith overlying fractured-crystalline rock. The regolith is weathered remains of crystalline rock. Most of the groundwater storage is within the regolith. The fracture-crystalline rock is mostly metamorphic rock with igneous intrusions and some Triassic sedimentary rock. This data release is made up of 17 directories, one for each well, plus general support files. Within the 17 well directories are files specific to the wells. Files in each directory include water-level data files as recorded by In-Situ Level Troll 700 self-logging pressure transducer during the time that one or two slug tests were being performed in the well, culled-data files containing small, manageable time-series of water levels that represent the slug test, and a copy of the field form. The culled data were analyzed in an analysis_BR spreadsheet that uses concepts from the Bouwer and Rice (1976) and is described in Halford and Kuniansky (2002). This data release also contains support files that summarize information about the data files and culled-data files, well characteristics, analyses, results, manual water-level measurements, and metadata (*.xml and README.txt).

A water-supply plan is being developed for Wake County, North Carolina, in accordance with the 50-year planning window used by the North Carolina Division of Water Resources for residents in unincorporated areas of the county. To develop this supply plan, Wake County seeks to better understand the sustainability of groundwater resources of the regolith/fractured-rock aquifer system. Slug tests were performed in 17 wells in the Wake County area, during 2020 and 2021, to provide values of horizontal hydraulic conductivity and transmissivity to support the development of Wake County’s water-supply plan. Wake County is in the Piedmont physiographic province. The two principal aquifers are nonconsolidated regolith overlying fractured-crystalline rock. The regolith is weathered remains of crystalline rock. Most of the groundwater storage is within the regolith. The fracture-crystalline rock is mostly metamorphic rock with igneous intrusions and some Triassic sedimentary rock. This data release is made up of 17 directories, one for each well, plus general support files. Within the 17 well directories are files specific to the wells. Files in each directory include water-level data files as recorded by In-Situ Level Troll 700 self-logging pressure transducer during the time that one or two slug tests were being performed in the well, culled-data files containing small, manageable time-series of water levels that represent the slug test, and a copy of the field form. The culled data were analyzed in an analysis_BR spreadsheet that uses concepts from the Bouwer and Rice (1976) and is described in Halford and Kuniansky (2002). This data release also contains support files that summarize information about the data files and culled-data files, well characteristics, analyses, results, manual water-level measurements, and metadata (*.xml and README.txt).

This data release has three components for each of the eight surveys that were conducted in 2018: 1) a geospatial dataset of the processed data; 2) tabular data of the processed waterborne resistivity profiling data and associated water-quality data; 3) tabular data of the raw waterborne resistivity data and associated water-quality data. In addition to the newly collected data from 2018, the waterborne resistivity data from 2016 (Miller and others, 2016) is included and has been re-processed to be consistent with the processing steps currently utilized and described herein. In fresh water aquifers, the geoelectric resistivity of earth materials commonly has a positive correlation with hydraulic conductivity (Faye and Smith, 1994). Throughout 2018, continuous resistivity profiling data were collected, as a proxy for streambed hydraulic conductivity, along reaches of eight streams in the Mississippi Alluvial Plain of Mississippi, Arkansas, and Missouri. A total of 906 kilometers (km) of continuous resistivity profiles were collected on 4 major streams and 4 reservoirs/lakes during several field excursions in 2018. Individual lengths of surveyed profiles per river include; 445 km on the White River, 225 km on the Black River, 76 km on the Cache, and 23 km on the Quiver River. Additionally, length of surveyed profiles on the reservoirs and lakes include; 64 km on Eutah Bend, 41 km on Roebuck Lake, 19 km on a United States Department of Agriculture On-Farm Storage Reservoir (USDA_OFS), and 13 km on Sky Lake. These river reaches and lakes were selected to aid in calibration of a regional groundwater model, specifically with regards to surface water-groundwater interaction. Stream reaches surveyed in 2016, which are included as part of this data release include; 50 km on the Quiver River, 70 km on the Sunflower River, and 61 km on the Tallahatchie River. The electrical resistance is calculated by dividing the measured voltage by the applied current. The apparent resistivity is determined by multiplying the electrical resistance by a geometric factor. Apparent resistivity is not the true resistivity because a homogeneous subsurface is assumed. To estimate the true resistivity or the resistivity structure where the subsurface is heterogeneous and/or anisotropic, the apparent resistivity data were processed using an inverse modeling software program. Since these data have not been modeled they should only be used qualitatively. Methodology relating to field data collection and data processing can be found in Miller and others (2018). Data collected during each survey include: Latitude, longitude, elevation of the water surface, water depth, water resistivity, injected current, voltage, measured apparent resistivity, and electrode location (referenced to the position of the GPS receiver). References: Faye, R.E., and Smith, W.G., 1994, Relations of borehole resistivity to the horizontal hydraulic conductivity and dissolved-solids concentration in water of clastic coastal plain aquifers in the southeastern United States., U.S. Geological Survey Water Supply Paper 2414, 33 p, https://doi.org/10.3133/wsp2414. Miller, B.V., Wallace, D.S., and Kress, W.H., 2016, Water-borne continuous resistivity profiling data from select streams of the Mississippi Alluvial Plain in northwestern Mississippi: U.S. Geological Survey data release, https://doi.org/10.5066/F7FT8J68. Miller, B.V., Adams, R.F., Stocks, S.J., Wilson, J.L., Smith, D.C., and Kress, W.H., 2018, Waterborne resistivity surveys for streams in the Mississippi Alluvial Plain, 2017: U.S. Geological Survey data release, https://doi.org/10.5066/F71J98ZQ.

This data release has three components for each of the eight surveys that were conducted in 2018: 1) a geospatial dataset of the processed data; 2) tabular data of the processed waterborne resistivity profiling data and associated water-quality data; 3) tabular data of the raw waterborne resistivity data and associated water-quality data. In addition to the newly collected data from 2018, the waterborne resistivity data from 2016 (Miller and others, 2016) is included and has been re-processed to be consistent with the processing steps currently utilized and described herein. In fresh water aquifers, the geoelectric resistivity of earth materials commonly has a positive correlation with hydraulic conductivity (Faye and Smith, 1994). Throughout 2018, continuous resistivity profiling data were collected, as a proxy for streambed hydraulic conductivity, along reaches of eight streams in the Mississippi Alluvial Plain of Mississippi, Arkansas, and Missouri. A total of 906 kilometers (km) of continuous resistivity profiles were collected on 4 major streams and 4 reservoirs/lakes during several field excursions in 2018. Individual lengths of surveyed profiles per river include; 445 km on the White River, 225 km on the Black River, 76 km on the Cache, and 23 km on the Quiver River. Additionally, length of surveyed profiles on the reservoirs and lakes include; 64 km on Eutah Bend, 41 km on Roebuck Lake, 19 km on a United States Department of Agriculture On-Farm Storage Reservoir (USDA_OFS), and 13 km on Sky Lake. These river reaches and lakes were selected to aid in calibration of a regional groundwater model, specifically with regards to surface water-groundwater interaction. Stream reaches surveyed in 2016, which are included as part of this data release include; 50 km on the Quiver River, 70 km on the Sunflower River, and 61 km on the Tallahatchie River. The electrical resistance is calculated by dividing the measured voltage by the applied current. The apparent resistivity is determined by multiplying the electrical resistance by a geometric factor. Apparent resistivity is not the true resistivity because a homogeneous subsurface is assumed. To estimate the true resistivity or the resistivity structure where the subsurface is heterogeneous and/or anisotropic, the apparent resistivity data were processed using an inverse modeling software program. Since these data have not been modeled they should only be used qualitatively. Methodology relating to field data collection and data processing can be found in Miller and others (2018). Data collected during each survey include: Latitude, longitude, elevation of the water surface, water depth, water resistivity, injected current, voltage, measured apparent resistivity, and electrode location (referenced to the position of the GPS receiver). References: Faye, R.E., and Smith, W.G., 1994, Relations of borehole resistivity to the horizontal hydraulic conductivity and dissolved-solids concentration in water of clastic coastal plain aquifers in the southeastern United States., U.S. Geological Survey Water Supply Paper 2414, 33 p, https://doi.org/10.3133/wsp2414. Miller, B.V., Wallace, D.S., and Kress, W.H., 2016, Water-borne continuous resistivity profiling data from select streams of the Mississippi Alluvial Plain in northwestern Mississippi: U.S. Geological Survey data release, https://doi.org/10.5066/F7FT8J68. Miller, B.V., Adams, R.F., Stocks, S.J., Wilson, J.L., Smith, D.C., and Kress, W.H., 2018, Waterborne resistivity surveys for streams in the Mississippi Alluvial Plain, 2017: U.S. Geological Survey data release, https://doi.org/10.5066/F71J98ZQ.

Since the 1940's, commercial, academic and government hydrologists have used aquifer tests to estimate the hydrogeologic properties of an aquifer near test wells. Results from these tests are recorded in various files, databases, reports, and scientific publications. The Lower Mississippi-Gulf (LMG)-Hydrogeologic Test dataset is an attempt to aggregate these dispersed hydrogeologic test results into a single dataset that is publicly available in a machine-readable format. The hydrogeologic values presented in the Mar2022 version of the LMG-Hydrogeologic Test Dataset were estimated by Douglas Carlson, PhD, with the Louisiana Geological Survey and Associate Professor-Research at Louisiana State University. Hydraulic conductivity estimates were made from specific capacity data using a technique developed by Bradbury and Rothschild (1985). Specific capacity values, from well pumping tests, were obtained from the Louisiana Water Well Registration Database. This Child Item contains the Mar2022 version of the LMG-Hydrogeologic Test dataset with information and results from 7527 aquifer tests. Additionally, this dataset contains 6 attribute tables (.txt files) with additional information for various fields, a zip file containing the geospatial data, a companion attribute table as a .txt file and a readme text file with definitions and descriptions of the attributes and attribute tables. The LMG-Hydrogeologic Aquifer Test dataset - Mar2022 is available in 2 formats: 1) a tab delimited text (.txt) UTF-8 file and 2) an ESRI GIS point shapefile. FIELDS INCLUDED IN THE LMG-HYDROGEOLOGIC TEST DATASET – Mar2022: [a complete list of field names, their definitions and units are listed in the Readme.txt file] Location Data: USGS site identification number, Local identification name, Public Land Survey System Number, Latitude, Longitude, State and County. Well Construction Data: Construction date, well depth, Diameter of well, Diameter of casing, Depth to top of opening (screen) interval, Depth to bottom of opening interval and Length of opening interval. Aquifer Data: Local aquifer name and code, National aquifer name and code, Top of aquifer, Bottom of aquifer, and Thickness of aquifer. Groundwater Test Data: Test date, Yield/discharge, Length of time associated with yield, Static water-level, Production water-level associated with yield, Drawdown associated with yield. Hydrogeologic Data: Specific Capacity, Transmissivity, Horizontal Conductivity, Vertical Conductivity, Permeability and Storage Coefficient. Ancillary Data: Method of Test Analysis and Data Source Reference. DESCRIPTIONS OF ATTACHED FILES: LMG_HydrogeologicTestDataset_Mar2022.txt: is a tab delimited, UTF-8 text file of the LMG-Hydrogeologic Test Dataset Mar2022. Readme.txt: is a text (.txt) file with field names, definitions and units for the LMG-Hydrogeologic Test Dataset Mar2022 and associated attribute tables. AtbtTbl_AqfrCd_Readme.txt: Is an UTF-8 text file containing information from the National Water Information System: Help System web page about USGS groundwater Codes. (accessed December 4, 2019 at https://help.waterdata.usgs.gov/codes-and-parameters) AtbtTbl_FipsGeographyCodes.txt: Is a tab delimited, UTF-8 text file of FIPS (Federal Information Processing Standards) codes, uniquely identifying states, counties and county equivalents in the United States. Note: to reduce the size of this file, City Codes were Removed. (accessed January 8, 2020 at https://www.census.gov/geographies/reference-files/2017/demo/popest/2017-fips.html). AtbtTbl_LocalAqfrCodes.txt: Is a tab delimited, UTF-8 text file of eight-character string identifying an aquifer. Codes are defined by the "Catalog of Aquifer Names and Geologic Unit Codes used by the USGS. (accessed December 4, 2019 at https://help.waterdata.usgs.gov/aqfr_cd) AtbtTbl_NatAqfrCodes.txt: Is a tab delimited, UTF-8 text file of ten-character strings identifying a National aquifer, or principal aquifer of the United States, that