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 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 https://water.usgs.gov/ogw/NatlAqCode-reflist.html) AtbtTbl_TstMthdCodes.txt: Is a tab delimited, UTF-8 text file of codes identifying the test analysis method when reported in the associated reference. AtbtTbl_DataRefNo.txt: Is a tab delimited, UTF-8 text file of references for the source of the associated aquifer test result. CAVEAT: The hydrogeologic test results reported in this dataset have not been through the USGS data review and approval process to receive the Director’s approval. As such, the Mar2022 version of the LMG-Hydrogeologic Test dataset should be considered provisional. Provisional data are released on the condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its use. This dataset was developed as part of the U.S. Geological Survey, Mississippi Alluvial Plain Regional Water-Availability Study.