DOI: 10.5066/p94640em
title: Data for depth of groundwater used for drinking-water supplies in the United States (ver. 2.0, January 2026)

description: This data release includes grids representing the depth and thickness of drinking-water withdrawal zones, polygons of hydrogeologic settings, an inventory of sources of well construction data, and summaries of data comparisons used to assess the depth of groundwater used for drinking-water supplies in the United States. Well construction data sources are documented in Table1_DataSources.xlsx. Data comparisons using the Mann-Whitney test to assess similarity between hydrogeologic settings were used to justify combining data where they were sparse (compare_neighbors_all_domestic.txt and compare_neighbors_all_public.txt). Water-supply-well depth varies geographically by water use and the type of well, which illustrates the need to identify the depth of domestic drinking water withdrawal and depth of public supply drinking water withdrawal zones. Water-supply-well depth also varies by aquifer; therefore median values were calculated for each Principal Aquifer (PA), Secondary Hydrogeologic Region (SHR) between PAs and PA or SHR associated with overlying sediment polygons, where present, including glacial (G), coarse glacial (GC), and stream-valley alluvium (AV) polygons (all termed hydrogeologic settings here). A polygon shape file of hydrogeologic settings is included in this data release (HG_Settings.zip) and includes well counts and median thicknesses and depths for each area. This data release documents an inventory of well construction data sources and thickness and median top and bottom of drinking water depth zones by aquifer for domestic and public supplies. This data release includes equations used for estimating information for wells missing information on the depth to the top/length of the open interval.

This data release contains:

HG_Settings.zip --Shape file with well counts and median depth and thickness for hydrogeologic setting areas

compare_neighbors_all_domestic.txt --results of Mann-Whitney tests to assess domestic-supply well construction data
        similarity between hydrogeologic settings

compare_neighbors_all_public.txt --results of Mann-Whitney tests to assess public-supply well construction data
        similarity between hydrogeologic settings

Depth_of_Drinking_Water_Supplies_Metadata07232021.xml --Metadata

NonReferencedDomestic.txt --An inventory of domestic-supply well data that are not published elsewhere

NonReferencedPublic.txt --An inventory of public-supply well data that are not published elsewhere

Table1_DataSources.xlsx --An inventory of databases, references, state web sites, and individual state contacts for
        data sources. The logic behind data extraction algorithms is also defined for each data source. A tab delimited
        text version with the same name is also available.

Lithology_OpenIntervalLengthFit.txt --Parameters for equations used for estimating open intervals by lithology,
        overlying sediment, and well type

HydrogeologicSetting_OpenIntervalLengthFit.txt --Parameters for equations used for estimating open intervals by
       hydrogeologic setting and well type

domestic_grids.zip contains:

    domestic_bottom_dist_to_5.asc --Grid of domestic-supply well open interval bottom depth data density, distance
        to reach 5 wells with information on the bottom of the open interval

    domestic_open_dist_to_5.asc --Grid of domestic-supply well  open interval length data density, distance to reach
        5 wells with information on open interval length

    domestic_bottom_open.asc --Grid of domestic-supply well  depth to the bottom of the open interval

    domestic_len_open.asc --Grid of domestic-supply well open-interval length

    domestic_top_open.asc --Grid of domestic-supply well  depth to the top of the open interval

public_grids.zip contains:

    public_bottom_dist_to_5.asc --Grid of the public-supply well open interval bottom depth data density, distance
         to reach 5 wells with information on the bottom of the open interval

    public_open_dist_to_5.asc --Grid of the public-supply well open interval length data density, distance to reach 5
         wells with information on open interval length

    public_bottom_open.asc --Grid of the public-supply well depth to the bottom of the open interval

    public_len_open.asc --Grid of the public-supply well open-interval length

    public_top_open.asc --Grid of the public-supply well depth to the top of the open interval

pubdom_difference_grids.zip contains:

    pubdom_bottom_open_diff.asc --Grid of the differences between the public-supply and domestic-supply well moving
        median surfaces representing the bottom of the open interval

    pubdom_len_open_diff.asc --Grid of the differences between the public-supply and domestic-supply well moving
        median surfaces representing the length of the open interval

    pubdom_top_open_diff.asc --Grid of the differences between the public-supply and domestic-supply well moving
        median surfaces representing the top of the open interval