National Water Availability and Use Program and National Water-Quality Assessment Program

Maps and Grids of Hydrogeologic Information 

Created from Standardized Water-Well Drillers’ Records 

of the Glaciated United States

 0 466

120° 110° 100° 90° 80° 70°

40°

30° 180° 160°

60°

50° 0 250 500 MILES

0 250 500 KILOMETERS

0 250 500 MILES

0 250 500 KILOMETERS

Base from U.S. Geological Survey digital data,1998, 

Albers Equal-Area Conic projection

Standard parallels 29°30'N and 45°30'N

Central meridian 96°00'W

EXPLANATION

Areas of insufficient data

Glacial extent boundary

Total thickness of coarse-grained 

sediment within the glacial 

deposits, in feet

91° 89° 87°

42°

40°

38°

0 30 60 90 MILES

0 60 90 KILOMETERS 30

Illinois Driftless Area

(unglaciated)

614.7 square miles 

224

0

EXPLANATION

Thickness of coarse-grained 

sediment within the 

glacial deposits, in feet

Glacial extent boundary 

Base from U.S. Geological Survey digital data, 1998, 

Albers Equal-Area Conic projection 

Standard parallels 29°30' and 45°30' Central meridian 96°00'

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2015–5105
Cover figures. Total thickness of coarse-grained sediment within the glacial deposits of 

the United States (left), and map created during this study showing the total thickness of 

coarse-grained sediment within the glacial deposits in Illinois (right).
Maps and Grids of Hydrogeologic 

Information Created from Standardized 

Water-Well Drillers’ Records of the 

Glaciated United States

By E. Randall Bayless, Leslie D. Arihood, Howard W. Reeves, Benjamin J.S. Sperl, 

Sharon L. Qi, Valerie E. Stipe, and Aubrey R. Bunch

National Water Availability and Use Program 

and the National Water-Quality Assessment Program

Scientific Investigations Report 2015–5105

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Director

U.S. Geological Survey, Reston, Virginia: 2017

For more information on the USGS—the Federal source for science about the Earth, its natural and living 

resources, natural hazards, and the environment—visit http://www.usgs.gov or call 1–888–ASK–USGS.

For an overview of USGS information products, including maps, imagery, and publications, 

visit http://store.usgs.gov.

Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials 

as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:

Bayless, E.R., Arihood, L.D., Reeves, H.W., Sperl, B.J.S., Qi, S.L., Stipe, V.E., and Bunch. A.R., 2017, 

Maps and grids of hydrogeologic information created from standardized water-well drillers’ records of the 

glaciated United States: U.S. Geological Survey Scientific Investigations Report 2015–5105, 34 p., 

https://doi.org/10.3133/sir20155105.

ISSN 2328-0328 (online)
iii

Acknowledgments

The authors acknowledge the employees of the State agencies that compiled and provided the 

digital water-well drillers’ records that were used as the basis for this study. The authors also 

acknowledge the following individuals for manually adding additional records: Myles S. Downhour 

(Indiana University-Purdue University Indianapolis), Jeremy D. Ferguson (Ball State University), 

Alexandria L. Heald (Ball State University), René M. Lawson (Ball State University), Lewis J. Mason 

(Indiana University), Dawn R. McCausland (self-employed contractor), Ben A. Weber (Indiana 

University-Purdue University Indianapolis), and Stacy L. Yager (Ball State University).

v

Contents

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Purpose and Scope ..............................................................................................................................2

Geologic Setting....................................................................................................................................2

Sources of Water-Well Drillers’ Records ..................................................................................................5

Methods for Creating the Standardized Maps and Grids of Hydrogeologic Information..................7

Processing Water-Well Drillers’ Records.........................................................................................7

Standardizing Lithologic Names ........................................................................................................7

Computing Parameter Values from Water-Well Drillers’ Records ...............................................9

Eliminating Errors and Assuring Quality in Data from Water-Well Drillers’ Records..............10

Generating Maps and Grids of Hydrogeologic Information ........................................................11

Comparing Maps of Hydrogeologic Information with Maps from Other Studies .............................27

The Ground Water Atlas of the United States ...............................................................................27

Williston Basin Groundwater Availability Study............................................................................32

Potential Uses of the Maps and Grids of Hydrogeologic Information ................................................32

Limitations of the Maps of Hydrogeologic Information.........................................................................32

References Cited..........................................................................................................................................34 

Figures

1. Map showing areas of the United States overlain by glacial deposits...............................3

2. Map showing areas of North America affected by Cordilleran and Laurentide 

ice sheets.......................................................................................................................................4

3. Flow chart for processing well logs into grids of hydrogeologic information....................8

4. Map showing the spatial density of water-well drillers’ records in the glaciated 

United States ...............................................................................................................................12

5 A–B. Maps showing the hydrogeologic information for Indiana as an example of State 

maps included in the nationwide mosaics. (Maps of hydrogeologic information 

for Indiana created from the standardized database of water-well drillers’ records, 

including: A, wells completed in bedrock, and B, wells completed in glacial 

deposits).......................................................................................................................................13

5 C–D. Maps showing the hydrogeologic information for Indiana as an example of State maps 

included in the nationwide mosaics. (Maps of hydrogeologic information for Indiana 

created from the standardized database of water-well drillers’ records, including: 

C, wells completed in glacial deposits and penetrating at least 50 percent of the total 

glacial thickness, and D, total thickness of glacial deposits) .....................................................14

5 E–F. Maps showing the hydrogeologic information for Indiana as an example of State maps 

included in the nationwide mosaics. (Maps of hydrogeologic information for Indiana 

created from the standardized database of water-well drillers’ records, including: 

E, thickness of coarse-grained sediment within the glacial deposits, and 

F, texture-based estimated equivalent horizontal hydraulic conductivity)...............................15
vi

5 G–H. Maps showing the hydrogeologic information for Indiana as an example of State 

maps included in the nationwide mosaics. (Maps of hydrogeologic information for 

Indiana created from the standardized database of water-well drillers’ records, 

including: G, texture-based estimated equivalent vertical hydraulic conductivity, and 

H, texture-based estimated equivalent transmissivity of the glacial deposits) .......................16

5 I–J. Maps showing the hydrogeologic information for Indiana as an example of State maps 

included in the nationwide mosaics. (Maps of hydrogeologic information for Indiana 

created from the standardized database of water-well drillers’ records, including: 

I, wells completed in bedrock having specific-capacity data, and J, wells completed 

in glacial deposits having specific-capacity data) .......................................................................17

5 K–L. Maps showing the hydrogeologic information for Indiana as an example of State 

maps included in the nationwide mosaics. (Maps of hydrogeologic information for 

Indiana created from the standardized database of water-well drillers’ records, including: K, wells completed in bedrock and glacial deposits withdrawing more than 

100 and 500 gallons per minute, and L, specific-capacity based horizontal hydraulic conductivity of coarse-grained sediment within the glacial deposits) ............................................18

5 M. Maps showing the hydrogeologic information for Indiana as an example of State 

maps included in the nationwide mosaics. (Maps of hydrogeologic information for 

Indiana created from the standardized database of water-well drillers’ records, 

including: M, specific-capacity based transmissivity of coarse-grained sediment 

within the glacial deposits) ...............................................................................................................19

6. Map showing the thickness of glacial deposits in the United States................................20

7. Map showing the total thickness of coarse-grained sediment within the glacial 

deposits of the United States....................................................................................................21

8. Map showing the specific-capacity based transmissivity of coarse-grained 

sediment within the glacial deposits of the United States ..................................................22

9. Map showing the specific-capacity based horizontal hydraulic conductivity of 

coarse-grained sediment within the glacial deposits of the United States......................23

10. Map showing the texture-based estimated horizontal hydraulic conductivity of 

the glacial deposits of the United States................................................................................24

11. Map showing the texture-based estimated vertical hydraulic conductivity of 

the glacial deposits of the United States................................................................................25

12. Map showing the texture-based estimated equivalent transmissivity of the 

glacial deposits of the conterminous United States.............................................................26

13. Map created during this study showing the total thickness of coarse-grained 

sediment within the glacial deposits in Illinois......................................................................28

14. Map from the Ground Water Atlas (Miller, 1999, fig. 4, p. K3) showing surficial 

and buried aquifers in unconsolidated deposits in Illinois ..................................................28

15. Map created during this study showing the thickness of glacial deposits in Illinois .....29

16. Map from the Ground Water Atlas (Miller, 1999, fig. 14, p. K6) showing the 

thickness of glacial deposits in Illinois ...................................................................................29

17. Map created during this study showing the thickness of glacial deposits in Iowa........30

18. Map from the Ground Water Atlas (Olcott, 1992, fig. 30, p. J9) showing the 

thickness of glacial deposits in Iowa ......................................................................................30

19. Map created during this study showing the total thickness of coarse-grained 

sediment within the glacial deposits in Iowa.........................................................................31

20. Map from the Ground Water Atlas (Olcott, 1992, fig. 6, p. J3) showing the 

distribution of coarse-grained sediment within the glacial deposits in Iowa..................31

Figures—Continued
vii

21. Map created during this study showing the thickness of glacial deposits in the 

part of North Dakota modeled by Thamke and others (2014)..............................................33

22. Map showing the thickness of glacial deposits in North Dakota created by 

Thamke and others (2014) .........................................................................................................33

Figures—Continued

Tables

1. Sources of water-well drillers’ records used to evaluate potential sources of 

information to derive hydrogeologic products ........................................................................6

2. List of data elements used to create the standardized maps and grids .............................9

Conversion Factors

U.S. customary units to International System of Units

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

Area

square mile (mi2

) 259.0 hectare (ha)

square mile (mi2

) 2.590 square kilometer (km2) 

Flow rate

foot per day (ft/d) 0.3048 meter per day (m/d)

gallon per minute (gal/min) 0.06309 liter per second (L/s)

million gallons per day (Mgal/d) 0.04381 cubic meter per second (m3

/s)

million gallons per day per square

mile [(Mgal/d)/mi2

]

1,461 cubic meter per day per square

kilometer [(m3/d)/km2]

Transmissivity*

foot squared per day (ft2

/d) 0.09290 meter squared per day (m2/d) 

Application rate

pounds per acre per year 

[(lb/acre)/yr]

1.121 kilograms per hectare per year

[(kg/ha)/yr]

Leakance

foot per day per foot [(ft/d)/ft] 1 meter per day per meter

inch per year per foot [(in/yr)/ft] 83.33 millimeter per year per meter

[(mm/yr)/m]
viii

Datum

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Altitude, as used in this report, refers to distance above the vertical datum.

Supplemental Information

Transmissivity: The standard unit for transmissivity is cubic foot per day per square foot times 

foot of aquifer thickness [(ft3/d)/ft2]ft. In this report, the mathematically reduced form, foot 

squared per day (ft2/d), is used for convenience.

Abbreviations

AML Arc Macro Language

ASCII American Standard Code for Information Interchange

GWSI Ground Water Site Inventory

INFO The database that supports geographic information system manipulations in ARC/INFO

JPEG Joint Photographic Experts Group

PDF Adobe portable document format

TIFF Tagged Image File Format

USGS U.S. Geological Survey
Maps and Grids of Hydrogeologic Information Created 

from Standardized Water-Well Drillers’ Records of the 

Glaciated United States

By E. Randall Bayless, Leslie D. Arihood1, Howard W. Reeves, Benjamin J.S. Sperl, Sharon L. Qi, 

Valerie E. Stipe2, and Aubrey R. Bunch

Abstract

As part of the National Water Availability and Use Program established by the U.S. Geological Survey (USGS) in 

2005, this study took advantage of about 14 million records 

from State-managed collections of water-well drillers’ records 

and created a database of hydrogeologic properties for the 

glaciated United States. The water-well drillers’ records were 

standardized to be relatively complete and error-free and to 

provide consistent variables and naming conventions that span 

all State boundaries.

Maps and geospatial grids were developed for (1) total 

thickness of glacial deposits, (2) total thickness of coarsegrained deposits, (3) specific-capacity based transmissivity 

and hydraulic conductivity, and (4) texture-based estimated 

equivalent horizontal and vertical hydraulic conductivity 

and transmissivity. The information included in these maps 

and grids is required for most assessments of groundwater 

availability, in addition to having applications to studies of 

groundwater flow and transport. The texture-based estimated 

equivalent horizontal and vertical hydraulic conductivity and 

transmissivity were based on an assumed range of hydraulic 

conductivity values for coarse- and fine-grained deposits and 

should only be used with complete awareness of the methods 

used to create them. However, the maps and grids of texturebased estimated equivalent hydraulic conductivity and transmissivity may be useful for application to areas where a range 

of measured values is available for re-scaling. 

Maps of hydrogeologic information for some States 

are presented as examples in this report but maps and 

grids for all States are available electronically at the project Web site (USGS Glacial Aquifer System Groundwater Availability Study, http://mi.water.usgs.gov/projects/

WaterSmart/Map-SIR2015-5105.html) and the Science 

Base Web site, https://www.sciencebase.gov/catalog/

item/58756c7ee4b0a829a3276352 (Bayless and others, 2017).

Introduction

At the request of Congress, the U.S. Geological Survey 

(USGS) is assessing the availability and use of the Nation’s 

water resources. In 2005, the USGS established the National 

Water Availability and Use program (U.S. Geological Survey, 

2002), which was designed to characterize the quantity of 

available surface and groundwater and improve understanding of trends in water use and future availability. This study 

also addresses the goals of the USGS National Water Census 

(U.S. Geological Survey, 2007, http://water.usgs.gov/watercensus/, accessed January 2, 2015) and the SECURE Water 

Act (National Science and Technology Council, 2007, http://

www.usbr.gov/climate/Secure/docs/SECUREWaterReport.pdf, 

accessed January 2, 2015). Those goals include developing 

new tools to facilitate assessments of water availability at the 

regional and national scale. The Great Lakes Basin was chosen 

as a pilot study area, and methods were developed to standardize water-well drillers’ records and create maps and geospatial 

grids of hydrogeologic information for the glaciated parts of 

the basin (Arihood, 2009). Those methods were adapted and 

enhanced for this study. 

Water-well drillers’ records may be the single largest source of data that are available to describe the geologic 

deposits of the subsurface. Drillers’ records are collected by 

one or more agencies in each State on a volunteer or mandated basis, and most are available online (Steve Schneider, 

Schneider Water Services, NGWA Groundwater Forum, written commun., 2014). Water-well drillers’ records generally 

include similar information, including well-location information, depth-specific descriptions of the geologic materials that 

were penetrated during drilling, the depth to groundwater, the 

dimensions and types of materials used to construct the well, 

and well-development data. The digital format of the drillers’ 

records varies among States and includes Microsoft Excel 

1

Scientist Emeritus, U.S. Geological Survey

2

 USGS Volunteer for Science
2 Maps and Grids of Hydrogeologic Information Created from Standardized Water-Well Drillers’ Records of the Glaciated United States

spreadsheets, Microsoft Access databases, geodatabases, text 

files, and scanned images in Joint Photographic Experts Group 

(JPEG) format or Adobe portable document format (PDF). 

The spatial density of water-well drillers’ records also varies 

greatly among States depending on the requirements of State 

laws, the level of driller cooperation, the preferred use of glacial aquifers relative to bedrock aquifers, and the occurrence 

and extent of glacial aquifers.

Regional hydrologic studies, such as the USGS National 

Water Availability and Use program investigations (http://

water.usgs.gov/ogw/gwrp/activities/water-avail-use.html, 

accessed January 4, 2014) and the USGS National WaterQuality Assessment Program (http://water.usgs.gov/nawqa, 

accessed January 4, 2014), can benefit greatly from regional 

maps and geospatial grids of hydrogeologic information. 

Those studies commonly examine areas that include multiple 

States. Standardized water-well drillers’ records include uniform data elements that are similarly populated and use similar 

terminology and physical units. The availability of nationwide 

standardized maps of hydrogeologic information facilitate 

hydrologic studies that cross State boundaries by eliminating 

(1) differences in the digital and layout formats that are present in various State-managed collections of water-well drillers’ 

records, (2) regional naming conventions for geologic deposits, and (3) errors that appear in water-well drillers’ records.

The maps and geospatial grids created as part of this 

study apply to a variety of hydrogeologic studies. As part of 

this study, for example, the geospatial grids were used to create maps of hydrogeologic information that describe the thickness and texture of unconsolidated glacial deposits and their 

related hydrologic characteristics. The distribution of geologic 

deposits form the framework of most groundwater studies, 

and it follows that the standardized maps and grids of hydrogeologic properties could be applied to studies of groundwater 

availability, flow, contaminant transport, aquifer recharge, 

and groundwater/surface-water interaction. Feinstein and 

others (2010), for example, used similarly constructed maps 

of hydrogeologic properties to construct a groundwater-flow 

model of the Lake Michigan drainage basin and examined the 

impacts of groundwater withdrawals on aquifer systems and 

stream discharges.

The methods used to create the geospatial grids and maps 

of hydrogeologic information were largely developed and 

documented for use in assessing water availability and use 

in the Lake Michigan drainage basin (Arihood, 2009). Those 

methods were augmented for this study with additional steps 

to further improve the quality of the records and to address the 

unique situations encountered within the various collections 

of water-well drillers’ records used for this study. This report 

focuses on the new processing steps and refers the reader to 

Arihood (2009) for the details of steps that were previously 

documented. 

This report addresses goals of the USGS National Water 

Census (http://water.usgs.gov/watercensus, accessed January 

2, 2015) and the SECURE Water Act (http://www.usbr/gov/

climate/SECURE/docs/SECUREWaterReport.pdf, accessed 

January 2, 2015) that pertain to developing new tools to 

facilitate assessments of water availability at the regional and 

national scale. This research also provides information that 

improves the decision-support capacity for water-resource 

managers. Information provided by the geospatial grids of 

hydrogeologic information can further facilitate the estimation 

of water availability in the Nation’s glacial aquifer systems.

Purpose and Scope

The purpose of this report is to describe (1) the contents 

of the standardized water-well drillers’ records and the derivative hydrogeologic products, (2) newly implemented methods 

used to standardize water-well drillers’ records for glaciated 

parts of the United States, (3) sources of water-well drillers’ 

records used in this study, (4) quality-assurance steps used to 

eliminate records with inconsistent or insufficient information, 

(5) new maps of hydrogeologic information, and (6) comparisons of maps created by this study with similar maps created 

by other studies. This report describes methods for creating 

geospatial grids and maps from water-well drillers’ records for 

U.S. territory that is overlain by glacial deposits (fig. 1), which 

includes all or part of 25 States and extends from the Atlantic 

Ocean to the Pacific Ocean and from Alaska to the Ohio River. 

About 14 million water-well drillers’ records from State-managed collections were used for this study. 

Geologic Setting

The glacial advances and retreats of the Pleistocene 

epoch (2,000,000 to 10,000 years BC; http://igs.indiana.edu/

Surficial/IceAge.cfm, accessed January 20, 2015) left vast 

deposits of various geologic materials over much of North 

America. The deposits west of the Rocky Mountain continental divide were deposited by the Cordilleran ice sheet, and the 

deposits east of the divide were deposited by the Laurentide 

ice sheet (fig. 2). The southern extent of glacial deposits generally includes areas north of the Missouri and Ohio Rivers. 

States included in this study and influenced by the Cordilleran 

ice sheet include Idaho, Washington, Alaska, and western 

Montana. The Laurentide ice sheet created the glacial deposits 

in the remaining 21 States included in this study.

In this study, water-well drillers’ records indicated that 

glacial deposits range from 0 to about 1,200 feet (ft) thick. 

Glacial deposits were absent in some areas of prominent 

bedrock highlands such as central Wisconsin and mountainous 

areas of the Rocky Mountains (fig. 1). The textures of glacial 

deposits range from very fine (clay-rich) lacustrine deposits 

to relatively coarse (sand and (or) gravel-rich) kames, eskers, 

outwash, and alluvial deposits. The variability of textures 

range from relatively homogeneous deposits of eolian sands 

with consistent texture through great thicknesses to glacial till 

deposits with heterogeneous mixtures of coarse- and finetextured materials. 
Introduction 3

 

 

 

 Extent of glacial deposits

EXPLANATION

0 250 500 MILES

0 250 500 KILOMETERS

Soller, D.R., Packard, P.H., and Garrity, C.P., 2012, Database for 

USGS Map I–970—Map showing the thickness and character of Quaternary 

sediments in the glaciated United States east of the Rocky Mountains.Flint, R.F., Alden, 

W.C., Apfel, E.T., Bostock, H.S., Capps, S.R., Goldthwait, J.W., Gould, L.M.,Kay, G.F., 

Leighton, M.M., Leverett, Frank, MacClintock, Paul, Nichols, D.A., Norman, H., Thwaites, 

F.T., White, G.W., and Young, G.A., 1945, Glacial map of North America.

Figure 1. Areas of the United States overlain by glacial deposits. 
4 Maps and Grids of Hydrogeologic Information Created from Standardized Water-Well Drillers’ Records of the Glaciated United States

150°

Cordilleran

 Ice Sheet

Laurentide Ice Sheet

140° 130° 120° 110° 100° 90° 80° 70° 60°

40°

50°

60°

NH

MA

RI

CN

NJ

DE

MD

ME

NY

CO

UT

NV

WY

ID

CA

OR

WA

PA

OH

MI

KY

VA WV

IL

WI

IN

MO

MN

IA

SD

NE

KS

MT

AZ

ND

VT

NC

CANADA

Basemap of states from U.S. Geological Survey 1:2,000,000 Digital Data Albers Equal-Area Conic 

projection, standard parallels 29° 30' and 45° 30', central meridian -96°, latitude of origin 23°

Mapped glacial regions are from U.S. Geological Survey DDS–38, Geological Society of America 

Glacial Map of North America (1945), and the Geological Survey of Canada's Late Wisconsinin and 

Holocene Retreat of the Laurentide Ice Sheet (1986)

2500 500 KILOMETERS

0 250 500 MILES

Unglaciated areas

Glaciated areas

EXPLANATION

Figure 2. Areas of North America affected by Cordilleran and Laurentide ice sheets.
Sources of Water-Well Drillers’ Records 5

The unlithified character of glacial deposits provides 

them with porosities that generally exceed the porosities of 

bedrock formations and creates in them the capacity to hold 

large quantities of groundwater (Warner and Arnold, 2006). 

Warner and Arnold (2006) reported that glacial aquifers 

comprise the largest principal aquifer system in the United 

States in areal extent and groundwater use for public supply in 

the United States. The areal extent, near-surface accessibility, 

and water-holding capacity explain the widespread utilization of glacial aquifers for domestic, agricultural, commercial, 

and industrial water supplies throughout much of the United 

States. During 2000, the total withdrawals of groundwater 

from the glacial aquifer system were approximately 3,560 million gallons per day (Mgal/d) and represented about 5 percent 

of total withdrawals from all aquifers in the United States 

(Maupin and Barber, 2005). Glacial sand-and-gravel aquifers 

east of the Rocky Mountains are largely used for public supply 

(1,950 Mgal/d), irrigation (1,020 Mgal/d), and self-supplied 

industrial (583 Mgal/d) uses (Maupin and Barber, 2005).

The vertical and lateral distribution of coarse- and finegrained deposits affects many aquifer characteristics, including the rate of aquifer replenishment (recharge), the interaction 

between groundwater and surface-water, the general chemistry 

of groundwater, and the movement of natural and anthropogenic compounds through the subsurface. These characteristics 

determine the potability and availability of groundwater for 

various uses. Inter-till aquifers, for example, may be overlain 

with significant thicknesses of fine-grained deposits near land 

surface. For this reason, inter-till aquifers may be slow to 

replenish and have limited water availability but also be well 

protected from chemicals applied at land surface. Outwash 

aquifers may include thick and extensive surficial deposits of 

sand and gravel. Those aquifers may be quicker to replenish 

and have greater availability than till aquifers but are more 

vulnerable to contamination from the chemicals applied at 

land surface.

Most U.S. States have maps that depict the surficial 

distribution of unlithified deposits, and many identify the 

morphological nature of the associated landforms. Those maps 

are largely two dimensional in perspective and do not portray 

variability with depth. Maps that display the three-dimensional 

geology of glacial deposits are less common; however, Soller 

and Reheis (2004) produced a large-scale map that shows the 

lateral and vertical distribution of coarse- and fine-grained 

deposits for glaciated terrains east of the Rocky Mountains. 

That map was later refined (Soller and others, 2012) and 

made available as geospatial grids. Other examples of glacial 

maps that provide three-dimensional information include, 

for example, Berg and Kempton (1988). This report contains 

maps and grids that provide extensive and detailed hydrogeologic information relative to the third dimension (depth), or 

that which lies beneath the surface features.

Sources of Water-Well Drillers’ 

Records

Water-well drillers’ records were acquired from the 

State agencies that are responsible for compiling and managing those records (table 1). Oil and gas well records, and 

records for drilling activities focused on mineral deposits in 

the bedrock, were another potential source of information for 

this study but those logs also do not normally contain detailed 

descriptions of the glacial deposits and hydraulic testing that 

were the focus of this study. As a result, only water-well drillers’ records were used for this study.

The collections of water-well drillers’ records that are 

managed by States vary in size, spatial density, completeness, 

digital format, and legal requirements. The number of digital water-well drillers’ records in State-managed collections 

for this study ranged from zero to more than 1 million. This 

number of records does not include those drillers’ records that 

might be available in paper form or as scanned forms. Only 

15 States had digital collections of water-well drillers’ records 

that included well-record information in a format that could 

be easily manipulated. The 10 remaining States had part or 

none of their collection of water-well drillers’ records in a 

digital form that was manipulatable by the programs used in 

this study. Rhode Island, for example, has collected thousands 

of paper records from water-well drillers that are not available in digital format. Other States, such as Washington and 

South Dakota, have well-construction information available in 

a manipulatable digital format but lithologic information was 

available only as scanned images of the original water-well 

drillers’ records.

The data elements sought by this study are unique site 

identifier, geographic location, well depth, water level, landsurface altitude, well screen depth and length, casing length 

and diameter, construction date, well development data (pump 

rate, pump duration, and drawdown), water use, owner, and 

the lithologies encountered at various depths during well 

installation. The data elements contained in State-managed 

collections of water-well drillers’ records were not always 

consistent. In general, data elements in most State collections 

included location, owner, intended water use, well construction, well development, and lithology. The data elements most 

commonly lacking in State collections of water-well drillers’ 

records were complete well-construction and well-development information. For the purposes of this study, missing wellconstruction and well-development data precluded the ability 

to compute aquifer transmissivity and hydraulic conductivity 

values. Water-well drillers’ records were not used to create 

maps and geospatial grids of hydrogeologic information if 

critical well-location and lithology data were missing.
6 Maps and Grids of Hydrogeologic Information Created from Standardized Water-Well Drillers’ Records of the Glaciated United States

Table 1. Sources of water-well drillers’ records used to evaluate potential sources of information to derive hydrogeologic products.

[shapefile, geospatial vector data for use with a geographic information system; PDF, Adobe portable document format; TIFF, tagged image file format; database, electronic database]

State1 Responsible agency

Original well 

construction 

file format

Original lithology 

file format

Alaska Alaska Department of Natural Resources shapefile PDF

Connecticut Connecticut Department of Consumer Protection TIFF TIFF

Idaho Idaho Department of Water Resources shapefile PDF

Illinois Illinois State Geological Survey database database

Indiana Indiana Department of Natural Resources database database

Iowa Iowa Department of Natural Resources database database

Iowa (2) University of Iowa database PDF

Kansas Kansas Geological Survey database PDF

Massachusetts Massachusetts Department of Environmental Protection database database

Maine Maine Geological Survey database database

Michigan Michigan Department of Environmental Quality database database

Minnesota Minnesota Geological Survey database database

Missouri Missouri Department of Natural Resources database database

Montana Montana Bureau of Mines and Geology database database

Nebraska incomplete Nebraska Department of Natural Resources database database

Nebraska (2) University of Nebraska database database

New Hampshire incomplete New Hampshire Department of Environmental Services database 

and PDF

database 

and PDF

New Jersey New Jersey Department of Environmental Protection database database

New York incomplete New York State Department of Environmental Conservation PDF PDF

North Dakota North Dakota State Water Commission database database

Ohio Ohio Department of Natural Resources database database

Pennsylvania insuffient data Pennsylvania Department of Conservation and Natural Resourcesdatabase database

Rhode Island incomplete Rhode Island Department of Health paper paper

South Dakota incomplete South Dakota Department of Environment & Natural Resources database PDF

Vermont Vermont Geological Survey shapefile shapefile

Washington incomplete Washington State Department of Ecology database PDF

Wisconsin Wisconsin Geological and Natural History Survey database database

Wisconsin (2) Wisconsin Department of Natural Resources database database

1

States with multiple agencies maintaining well-record databases are designated with a “(2)”.
Methods for Creating the Standardized Maps and Grids of Hydrogeologic Information 7

The water-well drillers’ records for some States did not 

include detailed descriptions of the glacial deposits. In those 

States, the primary source of potable water was usually bedrock aquifers or surface water and the unconsolidated deposits 

are commonly described as “overburden.” The glacial deposits in those areas may be thin or contain little coarse-grained, 

water-bearing material so that they are not useful aquifers. 

Those records were included in the analysis but may not provide 

the most reliable description of the lithology of the glacial 

deposits.

Methods for Creating the Standardized 

Maps and Grids of Hydrogeologic 

Information

The methods used in this study were largely documented 

in Arihood (2009). In that study, Arihood (2009) created maps 

and geospatial grids of hydrogeologic information for the 

glacial deposits in Michigan and parts of Indiana and Wisconsin. In this study, those methods have been augmented to adapt 

to the varied information encountered in water-well drillers’ 

records from all 25 glaciated States. Programming also was 

added to improve the efficiency of the well-record processing, 

create grids and maps of additional information, and provide 

easy construction of geological sections.

Processing Water-Well Drillers’ Records

Water-well drillers’ records were digitized by the USGS 

for States without records in a manipulatable format. Drillers’ 

records were manually entered into a spreadsheet for processing by the programs used in this study. The minimum number 

of well records needed to create reliable maps was estimated 

by examining the density of drillers’ records in States with 

existing digital collections that successfully produced sufficiently detailed maps of hydrologic information. For States 

with paper forms or PDF well records, wells were selected for 

entry using the following criteria: (1) geographic distribution 

across the glaciated region of that State, (2) other information 

that included well depth and (or) percentage of glacial deposits 

that were penetrated, and (3) availability of detailed lithologic 

description of the glacial deposits penetrated during well 

installation. The density of water-well drillers’ records could 

not be equally distributed in States with a predominance of 

valley-fill aquifers.

A system of Arc Macro Language (AML) programs was 

used to standardize water-well drillers’ records and create 

maps and geospatial grids of hydrogeologic information for 

the glaciated States (fig. 2). The data processing, algorithms, 

and underlying equations used to convert (1) water-well drillers’ descriptions into standard lithologic names used in the 

USGS Groundwater Site Inventory (GWSI), (2) standardized 

lithology descriptions into texture-based values of estimated 

equivalent horizontal and vertical hydraulic conductivity, and 

(3) well-development data into values of actual transmissivity 

and horizontal hydraulic conductivity are presented in Arihood 

(2009) and are not described in this report. Only new and (or) 

improved processing steps and related data manipulations are 

described herein. A general description of the work flow followed during well-record processing is shown in figure 3.

The agency responsible for managing water-well drillers’ records was contacted in each State and asked to provide 

their water-well drillers’ records in two data files identified as 

the site file and the lithology file (table 2). Additional information requested from the States was needed to describe the 

geographic projection and datum. Most States also provided 

a text file describing the information contained in each of the 

data fields. 

Data were provided to the USGS by the States in a 

variety of formats including Microsoft Excel spreadsheets; 

Microsoft Access databases; geodatabases; text files; and 

scanned images in JPEG, PDF, or TIFF format. Data were 

converted to tab-delimited text files that could be read by the 

AML programs. Data that were not necessary to processing 

steps, such as casing material, or information that might be 

considered to be personally identifiable information, such as 

street addresses, were deleted from the files.

Standardizing Lithologic Names

As described in Arihood (2009), the file of water-well 

drillers’ descriptions of lithologies that were encountered at 

various depth intervals was converted to an INFO file. The 

water-well drillers’ descriptions were then converted by an 

AML into geologic textural terms that are listed in the USGS 

GWSI lithology codes (Mathey, 1989, p. 2–110) and given an 

“aquifer” or “non-aquifer” material designation. The interpreted lithologies were spot-checked to assure that accurate 

translations of the drillers’ terms were made by the AML. 

Approximately 500 verification checks were made on each file 

of lithologies.

Lithologic terms were encountered during processing of 

water-well drillers’ records for the 25-State study area that had 

not been encountered during the Lake Michigan pilot study. 

About 1,000 lithologic descriptors were required to translate 

the water-well drillers’ descriptions into GWSI lithology 

codes.
8 Maps and Grids of Hydrogeologic Information Created from Standardized Water-Well Drillers’ Records of the Glaciated United States

ASCII file of 

lithologies

ASCII file of well-site 

information

(x-y, depth, water level)

INFO file of

lithologies

INFO file of standardized

lithologies and aquifer

classifications

Point coverage

of well-site 

information

Point coverage 

of all well-log 

information

Lithology

interpretation 

checks

County 

coverage 1

County 

coverage 2

County 

coverage 3

Remaining

county coverages

Calculate equivalent horizontal and vertical hydraulic conductivities for 

the entire glacial deposit using assumed values for the hydraulic 

conductivity of aquifer, nonaquifer, and unknown aquifer type

Combine county covers 

to one statewide cover

Interpolate point cover values 

with Inverse Distance Weighting 

to generate a statewide grid 

of hydrogeologic properties

Generate files for

automatic construction

of geologic sections

Calculate actual

transmissivities and

hydraulic conductivities

Statewide water-well

log database

Figure 3. Flow chart for processing well logs into grids of hydrogeologic information.
Methods for Creating the Standardized Maps and Grids of Hydrogeologic Information 9

Table 2. List of data elements used to create the standardized maps and grids.

Site file

Data element Description of data element

Unique site identifier The unique identifier assigned to each site by the State.

Horizontal coordinates Horizontal location information such as latitude and longitude.

Depth to water The depth to static water level below the measuring point.

Measuring-point elevation The elevation of the measuring point for the depth to water measurement.

Land-surface elevation The land-surface elevation at the well site.

Screen length The length of the well screen.

Casing length The length of the well casing.

Casing diameter The inner diameter of the casing.

Construction date The calendar date of the well construction.

Well-development rate The discharge rate of the pump during well development.

Well-development duration The duration of pumping during well development.

Well-development drawdown The decrease in potentiometric surface elevation during well development.

Lithology File

Data element1 Description of data element

Unique site identifier The unique identifier assigned to each site by the State.

Top of formation The depth below land surface to the top of the geologic formation.

Bottom of formation The depth below land surface to the bottom of the geologic formation.

Lithology The geologic description provided by the driller for the geologic deposits that exist 

between the top of formation and the bottom of formation. 

1

Data elements in the lithology file are repeated for each lithology described during drilling.

Computing Parameter Values from Water-Well 

Drillers’ Records

For each State, the INFO lithology file was joined to the 

well-site information point coverage and an AML program 

was used to calculate the texture-based estimated equivalent 

horizontal and vertical hydraulic conductivity, as in the previous study (Arihood, 2009). Specific-capacity based transmissivity and hydraulic conductivity values were computed for 

wells that included well-development information on the well 

record (Arihood, 2009). In this study, three new parameters 

were calculated: (1) total thickness of glacial deposits, (2) 

thickness of coarse-grained sediment within the glacial deposits, and (3) texture-based estimated equivalent transmissivity 

of the glacial deposits. 

The thickness over which the texture-based estimated 

equivalent transmissivity, horizontal hydraulic conductivity, 

and vertical hydraulic conductivity were applied depended 

on the availability of static water levels in the well-drillers’ 

records. The texture-based estimated equivalent hydraulic 

properties were computed for the saturated part of the glacial 

deposits from the static water-level elevation to the bedrocksurface elevation if a majority of the drillers’ records in the 

dataset contained static water levels. These values are more 

useful to most practicing hydrogeologists because they are 

pertinent to the portion of glacial deposits containing moving groundwater. The maps depicting texture-based estimated 

equivalent hydraulic conductivity and transmissivity indicate 

the upper altitude for the calculation (land surface or potentiometric surface). 

The texture-based estimated equivalent hydraulic 

properties were computed for the entire thickness of glacial 

deposits—from land-surface elevation to bedrock-surface 

elevation—if static water levels were not contained in the 

water-well drillers’ records. Static water-level depths were 

estimated for water-well records without such data in Stateprovided datasets where a majority of records did contain a 

reported static water level. This was done by fitting a polynomial least-squares regression relation to a plot of land-surface 

elevation with water-level elevation, and applying the derived 

relation to water-well records containing land-surface elevation (all wells) but no static water level. Only wells completed 

in the glacial deposits were used to compute this relation 

because wells completed in bedrock could portray confinedaquifer conditions and not indicate the water-table condition. 
10 Maps and Grids of Hydrogeologic Information Created from Standardized Water-Well Drillers’ Records of the Glaciated United States

It is recognized that this decision introduces some nonuniformity into the standardized maps and geospatial grids but 

it maximizes the value of the texture-based estimated equivalent hydraulic properties for States that record static water levels. The proximity of the static water level to land surface in 

most glaciated States, relative to the total thickness of glacial 

deposits, likely reduces the significance of this non-uniformity 

in the standardized products.

The texture-based values of equivalent transmissivity, horizontal hydraulic conductivity, and vertical hydraulic 

conductivity were computed based on a percentage of aquifer 

and non-aquifer material in the glacial deposits by assuming 

a horizontal hydraulic conductivity of 100 feet per day (ft/d) 

for aquifer material and 1 ft/d for non-aquifer material, and a 

vertical hydraulic conductivity of 10 ft/d for aquifer material 

and 0.001 ft/d for non-aquifer material. These values were 

selected because they were believed to represent the majority 

of values for glacial deposits and they would be easily scalable 

to future applications in hydrologic investigations. The point 

values of these parameters (texture-based equivalent estimated 

equivalent transmissivity, horizontal hydraulic conductivity, 

and vertical hydraulic conductivity) were extrapolated across 

the entire State by application of an inverse-distance weighting 

algorithm available within ArcInfo. Details of these methods 

are described in Arihood (2009).

For this study, however, it was determined that some 

States would not have the density of drillers’ records necessary 

to extrapolate a reliable map for the entire State. An AML was 

written to compute spatial density of drillers’ records according to the following equation:

(1)

where

D is the density of drillers’ records, in sites per 

square mile,

n is the number of sites in the glaciated part of 

the State penetrating at least 50 percent of 

the total thickness of glacial deposits,

A is the glaciated area of the State, in square 

miles.

The number and density of drillers’ records varied notably among States (fig. 4). Differences in the spatial density 

of drillers’ records may relate to the use of groundwater as 

a resource and (or) be related to the State’s emphasis on 

populating and maintaining a collection of water-well drillers’ 

records. Maps of hydrogeologic information were created for 

States with sufficient density of drillers’ records. A minimum 

density value of 0.2 wells per square mile (wells/mi2

) was 

determined to be sufficient to create reliable maps of hydrogeologic information. This value was assessed by comparing 

the maps generated by this study with maps of hydrogeologic 

information published by others. For States like Iowa, where 

drillers’ records appeared visually to be spatially well distributed across the glaciated part of the State, a well-record 

D nA = /

density of 0.2 wells/mi2 appeared visually to honor the distribution of glacial deposits shown in the Ground Water Atlas of 

the United States (“the Atlas”; Miller, 1999).

Eliminating Errors and Assuring Quality in Data 

from Water-Well Drillers’ Records

Many steps in the well-record processing were focused 

on eliminating well-log data that did not meet the standards 

established for this project, and those steps included frequently 

reviewing the results of the data manipulations to assure the 

quality of the finished product. Application of these steps 

reduced the available number of drillers’ records for each 

State. In some cases, the number of drillers’ records was 

reduced to the extent that it was not possible to construct maps 

of hydrogeologic information.

The following list describes the steps taken to eliminate errors and assure quality in the standardized water-well 

drillers’ records. Many of these steps were used in Arihood’s 

(2009) pilot study but were not documented. Some steps have 

been refined, and other steps have been added for this study 

including the following:

• Drillers’ records were eliminated that did not include 

the minimum set of required data, such as well-site 

location information.

• Drillers’ records with locations outside of the glaciated 

part of the State were eliminated.

• Thickness grids with negative values of total glacial 

thickness, calculated by subtracting bedrock elevation 

from land-surface elevation, were set to 1 ft. These 

instances may have occurred for various reasons 

including inaccuracies in the elevation data provided 

for the site. In this study, it was assumed that all sites 

have at least a 1 ft thickness of glacial deposits. If 

there were many locations with negative values of total 

thickness, or if the negative values were large, they 

were investigated. In some cases, a new land-surface 

or bedrock grid was acquired.

• Land-surface elevations from the water-well drillers’ 

records were compared with published maximum 

and minimum elevations for each State. Land-surface 

altitudes with elevations more than 20 ft beyond those 

extremes were deleted from the collection of records.

• Drillers’ records for a site where the upper elevation of 

a formation was higher than the base of the overlying 

formation resulted in deletion of all records for that 

site from the dataset. Also, all records for a site were 

deleted if any value for depth to the top of a formation 

was greater than the depth to the bottom of that formation.
Methods for Creating the Standardized Maps and Grids of Hydrogeologic Information 11

• All records of lithology for a well site were deleted if 

the AML program interpreted a lithologic record to be 

a glacial deposit located below bedrock. 

• The lithologies interpreted by the AML were spotchecked against the original driller’s description to 

help ensure accurate and consistent interpretations. 

• If the well log showed that the bedrock surface indicated on the water-well drillers’ record was lower than 

the Soller and others (2012) bedrock surface, then 

the well record was used and the depth to bedrock 

was modified to match the information in the drillers’ 

record.

• Maps of the thickness of coarse-grained deposits and 

the total thickness of glacial deposits were compared 

with published maps of the same, discrepancies were 

investigated, and errors were eliminated. 

• Each grid of hydrogeologic information was displayed 

and visually inspected for anomalous values. Anomalous data points were visually identified and corrected 

or eliminated.

• Any value of hydraulic conductivity calculated from 

specific-capacity data greater than 1,000 ft/d were 

assigned 1,000 ft/d.

• The State’s spatial density of water-well drillers’ 

records was evaluated for the adequacy to create reasonable maps of hydrogeological information.

• As a quality-assurance check, the total glacial-thickness values were examined. Well sites with glacialthickness values were deleted if they were clearly 

dissimilar to other nearby values.

Generating Maps and Grids of Hydrogeologic 

Information

The number and content of maps of hydrogeologic 

information generated for each State varied according to the 

density of water-well drillers’ records and the number of data 

elements contained in the State’s records. Only the waterwell drillers’ records that penetrated at least 50 percent of the 

total glacial thickness were used to construct the grids and 

maps of total thickness of glacial deposits; total thickness of 

coarse-grained deposits; and texture-based estimated equivalent transmissivity, horizontal hydraulic conductivity, and 

vertical hydraulic conductivity. The total glacial thickness at 

well sites was computed by (1) subtracting the value of the 

bedrock-surface elevation grid (Soller and others, 2012) from 

the land-surface elevation grid (http://agdc.usgs.gov/data/

usgs/erosafo/300m/300m.html, accessed February 20, 2015) if 

the well was completed above bedrock, or (2) subtracting the 

bedrock-surface elevation indicated in the water-well driller’s 

record from the land-surface elevation grid if the well was 

completed above or below the bedrock-surface elevation.

The following maps were created for States with drillers’ 

record densities exceeding 0.2 wells/mi2.

• Wells completed in bedrock.

• Wells completed in glacial deposits.

• Wells completed in glacial deposits and penetrating 

at least 50 percent of the total thickness of glacial 

deposits.

• Total thickness of glacial deposits in the United States.

• Thickness of coarse-grained sediment within the glacial 

deposits of the United States.

• Texture-based estimated equivalent horizontal hydraulic 

conductivity of the glacial deposits in the United States.

• Texture-based estimated equivalent vertical hydraulic 

conductivity of the glacial deposits in the United States.

• Texture-based estimated equivalent transmissivity of the 

glacial deposits in the United States.

The following additional maps were created for States with 

water-well drillers’ records that included well-development data.

• Wells completed in bedrock and having specific-capacity data.

• Wells completed in glacial deposits and having specificcapacity data.

• Wells completed in bedrock and glacial deposits withdrawing more than 100 and 500 gal/min, respectively.

• Specific capacity based horizontal hydraulic conductivity of coarse-grained sediment within the glacial deposits of the United States.

• Specific-capacity based transmissivity of coarse-grained 

sediment within the glacial deposits of the United 

States.

The density of water-well drillers’ records was satisfactory to create some maps and grids for most States (fig. 4). 

Water-well drillers’ records were lacking in density or detailed 

description of the unconsolidated geology in Alaska, Connecticut, Maine, Missouri, and New Jersey; glaciated parts of those 

states are identified in the maps of hydrogeologic information as areas of insufficient data. Parts of Idaho, Michigan, 

Minnesota, Montana, Vermont, Washington, and Wisconsin 

also contained areas of insufficient data. In those States, the 

water-well drillers’ record density was less than 0.2 wells/mi2

because the areas are sparsely populated or the hydrogeology 

is characterized by valley-fill aquifers. In States with valley-fill 

aquifers (where wells are concentrated in small areas), maps of 
12 Maps and Grids of Hydrogeologic Information Created from Standardized Water-Well Drillers’ Records of the Glaciated United States

120° 110° 100° 90° 80° 70°

40°

30° 180° 160°

60°

50° 0 250 500 MILES

0 250 500 KILOMETERS

0 250 500 MILES

0 250 500 KILOMETERS

Base from U.S. Geological Survey digital data,1998, 

Albers Equal-Area Conic projection

Standard parallels 29°30'N and 45°30'N

Central meridian 96°W

0 1,053

EXPLANATION

Areas of insufficient data

Glacial extent boundary

Number of water-well 

drillers’ records within 

one mile radius

Figure 4. Spatial density of water-well drillers’ records in the glaciated United States.

hydrogeologic information were only compiled for the valleyfill aquifers. Areas separating the valleys were not mapped 

because the inverse-distance weighting process could not 

generate reliable results.

Twelve States had the data required to create eight maps 

and grids and eight States had the data required to create 

13 maps and grids. The State of Indiana had a processed wellrecord density of 2.70 well/mi2

 and contained all of the data 

elements required to create a full suite of maps. The maps of 

hydrogeologic information created for the State of Indiana are 

provided as an example in figure 5. 

The maps and grids of hydrogeologic properties for the 

individual States were combined into nationwide grids to 

show regional trends and facilitate large-scale studies that 

cross State boundaries (figs. 6–12). The figures show where 

the hydrogeologic properties are mapped and areas with insufficient data. 
Figure 5 A–B. Hydrogeologic information for Indiana as an example of State maps included in the nationwide mosaics. (Maps of hydrogeologic infofrom the standardized database of water-well drillers’ records, including: A, wells completed in bedrock, and B, wells completed in glacial deposits.) A B 38° 39° 40C 41° 42° 87° 86° 85° 84° EXPLANATION Wells completed in bedrock Glacial extent boundary Base from U.S. Geological Survey 1:2,000,000 digital data Albers Equal-Area conic projection, Standard parallels 29C 30' N and 45° 30' N, Central meridian 96° W, latitude of origin 23° 20 40 60 MILES 0 20 40 60 KILOMETERS 0 38° 39° 40C 41° 42° 87° 86° 85° 

Base from U.S. Geological Survey, 1:2,000,000 digital data Albers Equal-Area conic projection, Standard parallels 29° 30' N and 45° 30' N, Central meridian 96° W, latitude of origin 23° 20 40 

0 20 40 60 KILOM0
Figure 5 C–D. Hydrogeologic information for Indiana as an example of State maps included in the nationwide mosaics. (Maps of hydrogeologic inforfrom the standardized database of water-well drillers’ records, including: C, wells completed in glacial deposits and penetrating at least 50 percent of and D, total thickness of glacial deposits.) C38° 39° 40C 41° 42° 87° 86° 85° 84° EXPLANATION Wells completed in glacial deposits and penetrating at least 50% of the total glacial thickness Glacial extent boundary Base from U.S. Geological Survey, 1:2,000,000 digital data Albers Equal-Area conic projection, Standard parallels 29° 30' N and 45° 30' N, Central meridian 96° W, latitude of origin 23° 20 40 60 MILES 0 20 40 60 KILOMETERS 0 D38° 39° 40C 41° 42° 87° 86° 85° 

Base from U.S. Geological Survey, digital data, 1998, 1:2,000,000 Albers Equal-Area conic projection, Standard parallels 29° 30' N and 45° 30' N, Central meridian 96° W 20 40 

0 20 40 60 0 
Figure 5 E–F. Hydrogeologic information for Indiana as an example of State maps included in the nationwide mosaics. (Maps of hydrogeologic inforfrom the standardized database of water-well drillers’ records, including: E, thickness of coarse-grained sediment within the glacial deposits, and F, tequivalent horizontal hydraulic conductivity.) E 88 ° 87 ° 86 ° 85 ° 84 ° 42° 41° 40° 39° 38° 0 10 20 30 40 MILES 0 10 20 30 40 KILOMETERS EXPLANATION 280.625 050 100 150 200 250 Base from U.S. Geological Survey digital data, 1998, 1:2,000,000 Albers Equal-Area Conic projection Standard parallels 29°30'N and 45°30'N Central meridian 96° W Thickness of coarse-grained sediment within the glacial deposits, in feet Glacial extent boundary F 87 ° 86 ° 85 ° 42° 41° 40° 39° 38° 0 10 20 

0 10 20 30 

Base from U.S. Geological Survey digital data, 1998, 1:2,000,000 Albers Equal-Area Conic projection Standard parallels 29°30'N and 45°30'N Central meridian 96°W 
Figure 5 G–H. Hydrogeologic information for Indiana as an example of State maps included in the nationwide mosaics. (Maps of hydrogeologic infofrom the standardized database of water-well drillers’ records, including: G, texture-based estimated equivalent vertical hydraulic conductivity, and H

equivalent transmissivity of the glacial deposits.) G 88 ° 87 ° 86 ° 85 ° 84 ° 42° 41° 40° 39° 38° Base from U.S. Geological Survey digital data, 1998, 1:2,000,000 Albers Equal-Area Conic projection Standard parallels 29°30'N and 45°30'N Central meridian 96°W 0 10 20 30 40 KILOMETERS 0 10 20 30 40 MILES 10 0.001 EXPLANATION Texture-based estimated equivalent vertical hydraulic conductivity of the glacial deposits, in feet per day Glacial extent boundary H 88 ° 87 ° 86 ° 85 ° 

42° 41° 40° 39° 38° Base from U.S. Geological Survey digital data, 1998, 1:2,000,000 Albers Equal-Area Conic projection Standard parallels 29°30'N and 45°30'N Central meridian 96°W 0 10 20 30 

0 10 20 
Figure 5 I–J. Hydrogeologic information for Indiana as an example of State maps included in the nationwide mosaics. (Maps of hydrogeologic inforfrom the standardized database of water-well drillers’ records, including: I, wells completed in bedrock having specific-capacity data, and J, wells co

having specific-capacity data.) I EXPLANATION Wells completed in bedrock having specific-capacity data 38° 39° 40° 41° 42° 87° 86° 85° 84° 20 40 60 MILES 0 20 40 60 KILOMETERS 0 Glacial extent boundary Base from U.S. Geological Survey, 1:2,000,000, digital data Albers Equal-Area conic projection Standard parallels 29°30'N and 45° 30'N Central meridian 96°W, latitude of origin 23° J EXPLANATION 20 

0 20 0 Glacial extent boundary Wells completed in glacial deposits having specific-capacity data Base from U.S. Geological Survey, 1:2,000,000, digital data Albers Equal-Area conic projection Standard parallels 29°30' and 45°30' Central meridian 96°, latitude of origin 23° 87° 86° 85° 

38° 39° 40° 41° 42°
Figure 5 K–L. Hydrogeologic information for Indiana as an example of State maps included in the nationwide mosaics. (Maps of hydrogeologic inforfrom the standardized database of water-well drillers’ records, including: K, wells completed in bedrock and glacial deposits withdrawing more than minute, and L, specific-capacity based horizontal hydraulic conductivity of coarse-grained sediment within the glacial deposits.) K EXPLANATION 20 40 60 MILES 0 20 40 60 KILOMETERS 0 Bedrock well site tested at greater than or equal to 100 gallons per minute Bedrock well site tested at greater than or equal to 500 gallons per minute Glacial well site tested at greater than or equal to 100 gallons per minute Glacial well site tested at greater than or equal to 500 gallons per minute Base from U.S. Geological Survey digital data, 1998, 1:2,000,000 Albers Equal-Area Conic projection Standard parallels 29°30'N and 45°30'N Central meridian 96°W 87° 86° 85° 84° 38° 39° 40° 41° 42° Glacial extent boundary L 0 10 20 30 

0 10 20 30 40 KIL

Base from U.S. Geological Survey digital data, 1998, 1:2,000,000. Albers Equal-Area Conic projection Standard parallels 29°30'N and 45°30'N Central meridian 96°W 87° 86° 85° 42° 41° 40° 39° 38°
Methods for Creating the Standardized Maps and Grids of Hydrogeologic Information 19

Figure 5 M. Hydrogeologic information for Indiana as an example of State maps 

included in the nationwide mosaics. (Maps of hydrogeologic information for Indiana 

created from the standardized database of water-well drillers’ records, including: 

M, specific-capacity based transmissivity of coarse-grained sediment within the 

glacial deposits.)

M

Base from U.S. Geological Survey digital data, 1998,1:2,000,000. 

Albers Equal-Area Conic projection

Standard parallels 29° 

Central meridian 96°

87° 86° 85°

42°

41°

40°

39°

38°

Glacial extent boundary

EXPLANATION

107675

0.192287

50000

75000

25000

0 10 20 30 40 MILES

0 10 20 30 40 KILOMETERS

Specific-capacity based transmissivity of 

coarse-grained sediment within the 

glacial deposits, in square feet per day
20 Maps and Grids of Hydrogeologic Information Created from Standardized Water-Well Drillers’ Records of the Glaciated United States

120° 110° 100° 90° 80° 70°

40°

30° 180° 160°

60°

50° 0 250 500 MILES

0 250 500 KILOMETERS

Base from U.S. Geological Survey digital data,1998, 

Albers Equal-Area Conic projection

Standard parallels 29°30'N and 45°30'N

Central meridian 96°00'W

0 250 500 MILES

0 250 500 KILOMETERS

1.59 855

EXPLANATION

Areas of insufficient data

Glacial extent boundary

Thickness of glacial 

deposits, in feet

Figure 6. Thickness of glacial deposits in the United States.
Methods for Creating the Standardized Maps and Grids of Hydrogeologic Information 21

 0 466

120° 110° 100° 90° 80° 70°

40°

30° 180° 160°

60°

50° 0 250 500 MILES

0 250 500 KILOMETERS

0 250 500 MILES

0 250 500 KILOMETERS

Base from U.S. Geological Survey digital data,1998, 

Albers Equal-Area Conic projection

Standard parallels 29°30'N and 45°30'N

Central meridian 96°00'W

EXPLANATION

Areas of insufficient data

Glacial extent boundary

Total thickness of coarse-grained 

sediment within the glacial 

deposits, in feet

Figure 7. Total thickness of coarse-grained sediment within the glacial deposits of the United States.
22 Maps and Grids of Hydrogeologic Information Created from Standardized Water-Well Drillers’ Records of the Glaciated United States

120° 110° 100° 90° 80° 70°

40°

30° 180° 160°

60°

50° 0 250 500 MILES

0 250 500 KILOMETERS

0 250 500 MILES

0 250 500 KILOMETERS

Base from U.S. Geological Survey digital data,1998, 

Albers Equal-Area Conic projection

Standard parallels 29°30'N and 45°30'N

Central meridian 96°00'W

0 175,264

EXPLANATION

Areas of insufficient data

Glacial extent boundary

Specific-capacity based transmissivity 

of coarse-grained sediment 

within the glacial deposits, 

in square feet per day

Figure 8. Specific-capacity based transmissivity of coarse-grained sediment within the glacial deposits of the United States.
Methods for Creating the Standardized Maps and Grids of Hydrogeologic Information 23

0 250 500 MILES

0 250 500 KILOMETERS

40°

30° 180° 170° 160° 150°

60°

50° 0 250 500 MILES

0 250 500 KILOMETERS

0.17 999

EXPLANATION

Areas of insufficient data

Glacial extent boundary

Specific-capacity based horizontal 

hydraulic conductivity of 

coarse-grained sediment within 

the glacial deposits, in feet per day

Base from U.S. Geological Survey digital data, 1998, 

Albers Equal-Area Conic projection

Standard parallels 29°30'N and 45°30'N

Central meridian 96°W

120° 110° 100° 90° 80° 70°

Figure 9. Specific-capacity based horizontal hydraulic conductivity of coarse-grained sediment within the glacial deposits of the United 

States.
24 Maps and Grids of Hydrogeologic Information Created from Standardized Water-Well Drillers’ Records of the Glaciated United States

120° 110° 100° 90° 80° 70°

40°

30° 180° 170° 160° 150°

60°

50° 0 250 500 MILES

0 250 500 KILOMETERS

0 250 500 MILES

0 250 500 KILOMETERS

0.5 100

EXPLANATION

Areas of insufficient data

Glacial extent boundary

Base from U.S. Geological Survey digital data,1998 

Albers Equal-Area Conic projection

Standard parallels 29°30'N and 45°30'N

Central meridian 96°W Texture-based estimated equivalent 

horizontal hydraulic conductivity 

of the glacial deposits, 

in feet per day

Figure 10. Texture-based estimated horizontal hydraulic conductivity of the glacial deposits of the United States.
Methods for Creating the Standardized Maps and Grids of Hydrogeologic Information 25

120° 110° 100° 90° 80° 70°

40°N

30° 180° 170° 160° 150°

60°

50°

0 250 500 MILES

0 250 500 KILOMETERS

0 10

EXPLANATION

Areas of insufficient data

Glacial extent boundary

Base from U.S. Geological Survey digital data, 1998, 

Albers Equal-Area Conic projection

Standard parallels 29°30'N and 45°30'N

Central meridian 96°W Texture-based estimated equivalent 

vertical hydraulic conductivity 

of the glacial deposits, 

in feet per day

0 250 500 MILES

0 250 500 KILOMETERS

Figure 11. Texture-based estimated vertical hydraulic conductivity of the glacial deposits of the United States.
26 Maps and Grids of Hydrogeologic Information Created from Standardized Water-Well Drillers’ Records of the Glaciated United States

0 250 500 MILES

0 250 500 KILOMETERS

Base from U.S. Geological Survey digital data, 1998, 

Albers Equal-Area Conic projection

Standard parallels 29°30'N and 45°30'N

Central meridian 96°W Texture-based estimated

equivalent transmissivity 

of the glacial deposits, 

in square feet per day 

1.74 46,596

Areas of insufficient data

Glacial extent boundary

EXPLANATION

120° 110° 100° 90° 80° 70°

40°

30° 180° 170° 160° 150°

60°

50° 0 250 500 MILES

0 250 500 KILOMETERS

Figure 12. Texture-based estimated equivalent transmissivity of the glacial deposits of the conterminous United States.
Comparing Maps of Hydrogeologic Information with Maps from Other Studies 27

Comparing Maps of Hydrogeologic 

Information with Maps from Other 

Studies

The maps of hydrogeologic information that were created 

during this study by processing water-well drillers’ records 

were compared with existing maps of the same or similar 

information to (1) qualitatively evaluate the accuracy of this 

study’s results, (2) discover areas where the addition of the 

third dimension (well logs) uncovers geologic detail not 

discernable from surface features, (3) discover inaccuracies in 

the well-log data, and (4) discover inaccuracies in the well-log 

interpretation process. Whenever inaccuracies were discovered, records were deleted or AML programs and processing 

steps were improved.

The Ground Water Atlas of the United States 

The Ground Water Atlas of the United States summarized 

available hydrogeologic information for the entire Nation 

using a common presentation format that included many maps 

(Miller, 1999). The maps and information in the Atlas were 

based on existing reports and files of the USGS and other 

agencies and often required combining multiple sources of 

information to cover the entire extent of the mapped regions. 

Those maps likely relied heavily on water-well drillers’ 

records but also may have used some combination of geophysical information and well logs used for oil, gas, and mineral 

exploration. The application of common methods to waterwell drillers’ records from the glaciated part of the Nation was 

a goal of this study, which made intercomparison with the 

Atlas a logical choice.

The maps of hydrogeologic information created during this study were routinely compared to maps of similar 

information shown in the Atlas. If discrepancies existed, they 

were investigated and adjustments were made if warranted. All 

things considered, the maps created during this study depicted 

the same spatial trends shown in the Atlas figures. 

The comparisons indicated that the trends in major and 

minor geologic features were generally honored by the maps 

created during this study; however, the density of drillers’ 

records was an important consideration in the resolution of 

minor geologic features in these maps. As examples, some 

maps for Illinois and Iowa are compared (herein) with maps 

of the same hydrogeologic information from the Atlas. 

About 197,000 water-well drillers’ records were available, 

after the processing steps described in this study, to create 

the standardized maps and grids for Illinois. The density of 

drillers’ records for the set of wells that penetrated more than 

50 percent of the glacial deposit thickness was 2.37 wells/mi2

. 

The map from this study showing the thickness of coarsegrained deposits was compared with the Atlas map showing 

surficial and buried aquifers in unconsolidated deposits in Illinois (Miller, 1999, fig. 4, p. K3) (figs. 13 and 14, respectively). 

The comparison shows significant deposits of sand and gravel 

representing buried aquifers and river alluvium in central 

and northcentral Illinois.The map of total thickness of glacial 

deposits generated during this study also compared favorably 

with the thickness map for Illinois in the Atlas (Miller, 1999, 

fig. 14, p. K6) (figs. 15 and 16, respectively). The maximum 

thickness shown in the Atlas is 400 to 600 ft, and the maximum thickness appearing on the map generated during this 

study is approximately 447 ft.

About 13,800 water-well drillers’ records in Iowa were 

available for map construction after the processing steps 

described in this study. The map of total thickness of glacial 

deposits that was produced during this study was compared 

with the map of total thickness of unconsolidated deposits in 

Iowa depicted in the Atlas (Olcott, 1992, fig. 30, p. J9) (figs. 

16 and 17, respectively). The comparison showed a similar distribution of the thickness of glacial deposits. In both 

maps, spatially extensive and thicker deposits occurred in the 

western part of the State and thinner deposits occurred along 

the eastern edge of the State. More spatially limited deposits, 

such as the thicker deposits in east-central Iowa, also appeared 

on both maps. The thickest deposits in the Atlas map were 400 

to 600 ft and compare favorably with a maximum thickness 

of 532 ft in the map created during this study. The density of 

drillers’ records in the maps shown for Iowa was about 0.25 

records per square mile after standardization, error removal, 

and eliminating logs that penetrated less than 50 percent of the 

total thickness of glacial deposit. This relatively low density of 

drillers’ records was counterbalanced by the even distribution 

of the logs and deposits across the State. 

The map of coarse-grained deposits generated during this 

study was compared with the distribution of surficial glacial 

sediments that appears in the Atlas for Iowa (Olcott, 1992, 

fig. 6, p. J3) (figs. 19 and 20, respectively). As discussed in 

Arihood (2009), some surficial deposits are good indicators of 

the nature of sediments at greater depth, such as those along 

the Missouri and Cedar Rivers. Most surficial sand and gravel 

deposits shown in the Atlas, however, are not indicative of the 

total thickness of sand and gravel that appears in the map created during this study; examples of this are the relatively thick 

sand and gravel deposits in eastern Iowa.
Figure 13. Map created during this study showing the total thickness of coarse-grained sediment within the glacial deposits in Illinois. Figure 14. Map from the Ground Water Atlas (M

p. K3) showing surficial and buried aquifers in uncdeposits in Illinois. 91° 89° 

42° 40° 38° EXPLANATION Base modified from U.S. Geological Survey digital data, 1:2000,000, 1972 Albers Equal-Area Conic projection, Standard parallels 29° 30’ and 45° 30’, Central meridian -96° 00’ Driftless Area 0 25 75 0 25 50 50 75 100 MILES 100 KILOMETERS Sand and gravel aquifers at or near land surface, and alluvium along streams and rivers—Patterned area shows Mississippi River Valley alluvium aquifer Sand and gravel aquifers buried beneath finer grained material Surfici

thaoccgraloc

Southe

91° 89° 87° 42° 40° 38° 224 0 Illinois Driftless Area (unglaciated) 614.7 square miles EXPLANATION Thickness of coarse-grained sediment within the glacial deposits, in feet Glacial extent boundary 0 30 60 120 MILES 0 60 120 KILOMETERS 30 Base from U.S. Geological Survey digital data, 1998, Albers Equal-Area Conic projection Standard parallels 29°30' and 45°30' Central meridian -96°00'
Figure 15. Map created during this study showing the thickness of glacial deposits in Illinois. Figure 16. Map from the Ground Water A

fig. 14, p. K6) showing the thickness of glaIllinois. 00 25 25 50 MILES 50 KILOMETERS Base modified from U.S. Geological Survey digital data, 1:2000,000, 197

Albers Equal-Area Conic projection Standard parallels 29° 30’ and 45° 30’, Central meridian -96° 00’ EXPLANATION Thickness of Quaternary deposi

Less than 100 100 to 200 200 to 400 400 to 600 Southern limit of glaciation 91° 89° 87° 91° 89° 

42° 40° 38° 42° 40° 38° 0 30 60 90 MILES 0 60 90 KILOMETERS 30 Illinois Driftless Area (unglaciated) 614.7 square miles 224 0 EXPLANATION Thickness of coarse-grained sediment within the glacial deposits, in feet Glacial extent boundary Illinois Driftless Area Base from U.S. Geological Survey digital data, 1998, Albers Equal-Area Conic projection Standard parallels 29°30' and 45°30' Central meridian -96°00'
Figure 17. Map created during this study showing the thickness of glacial deposits in Iowa. Figure 18. Map from the Ground Water Atlas (Olco

p. J9) showing the thickness of glacial deposits in Io

Iowa Driftless Area (unglaciated) 12.2 square miles 532.8 11.25 EXPLANATION Total thickness of glacial deposits, in feet 

Base modified from U.S. Geological Survey National Atlas, 1:2,000,000, 1970 Modified from unpubl

in the files of the U.S. 

Thickness of glacial deposits, in feet Less than 50 50 to 200 200 to 400 400 to 600 600 to 800 800 to 1,000 Limit of Driftless Area—Dashed wher

approximately located EXPLANATION 44° 96° 94° 92° 90° 96° 94° 92° 

42° 40° 44° 42° 40° 0 50 100 MILES 0 50 100 KILOMETERS 0 50 100 MILES 0 50 100 KILOMETERS Base from U.S. Geological Survey digital data, 1998, Albers Equal-Area Conic projection Standard parallels 29°30'N and 45°30'N Central meridian 96°W
Figure 19. Map created during this study showing the total thickness of coarse-grained sediment within the glacial deposits in Iowa. Figure 20. Map from the Ground Water Atlas (O

showing the distribution of coarse-grained sedimdeposits in Iowa. Base modified from U.S. Geological Survey National Atlas, 1:2,000,000, 1970 291 0 EXPLANATION Glacial extent boundary Thickness of coarse-grained deposits, in feet 96° 94° 92° 90° 44° 42° 40° 0 50 100 MILES 0 50 100 KILOMETERS 

EXPLANATION 96° 94° 9

44° 42° 40° C

Missouri River Glacial outwash, coarse-grained gla

sediment, and coarse- and fine-g

Areas where glacial deposits are thi

consist of unsorted, unstratified d

Base from U.S. Geological Survey digital data, 1998, Albers Equal-Area Conic projection Standard parallels 29°30'N and 45°30'N Central meridian 96°W Iowa Driftless Area (unglaciated) 12.2 square miles 
32 Maps and Grids of Hydrogeologic Information Created from Standardized Water-Well Drillers’ Records of the Glaciated United States

Williston Basin Groundwater Availability Study

The USGS Groundwater Resources Program examined 

groundwater use and availability in the Williston and Powder 

River Basins (Reilly and others, 2008). The hydrogeologic 

framework and related maps produced for the Williston and 

Powder River structural basins provided an opportunity to 

compare maps of hydrogeologic information created during 

that study (Thamke and others, 2014) with maps of similar information created during this study. The maps for the 

groundwater availability study in the Williston and Powder 

River Basins were created by synthesizing available information that included many publications, water-well drillers’ 

records, and geophysical information. These maps were used 

to improve understanding of the regional hydrogeologic 

framework and to support the construction of groundwaterflow models. The study area included parts of North Dakota, 

Montana, Saskatchewan, and Manitoba.

The map of total thickness of glacial deposits produced 

during this study was compared with the same information 

generated by the groundwater availability study for the Willison and Powder River Basins (figs. 21 and 22, respectively). 

In general, the absolute difference between the thickness of 

glacial deposits in both maps was less than 25 ft. The densities 

of post-processing drillers’ records in North Dakota was 0.22 

wells/mi2

. 

Potential Uses of the Maps and Grids 

of Hydrogeologic Information

There are many potential uses for the standardized maps 

and grids of hydrogeologic information. The gridded datasets 

of hydrogeologic information, particularly horizontal and 

vertical hydraulic conductivity, might be used in examining 

aquifer vulnerability, surface-water low-flow characteristics, 

groundwater/surface-water interaction, and groundwater 

recharge. Maps showing the thickness of coarse-grained 

deposits and total thickness of glacial deposits might be used 

for estimating groundwater storage. 

Limitations of the Maps of 

Hydrogeologic Information

The application of maps and grids of hydrogeologic 

information produced during this study to future hydrologic 

investigations should consider (1) the accuracy of the waterwell drillers’ records used to construct the standardized 

maps and grids, (2) the methods used to process the drillers’ 

records into the maps and grids, and (3) the density and spatial 

distribution of the water-well drillers’ records. The Ground 

Water Atlas of the United States (Miller, 1999) recommended 

that the small-scale maps shown in that report not be used for 

“local information or site-specific interpretations” (p. A3). In 

this study, the maps of hydrogeologic information are interpolated between the well-record locations using numerical 

methods. The applicability of these maps to large-scale studies 

should be evaluated based on the density of drillers’ records in 

the vicinity of the target area and the users’ confidence in the 

interpolation method relative to the geologic setting.

The interpretation of the drillers’ descriptions into GWSIcompatible names were spot-checked. Time constraints did not 

allow an inspection of all interpretations; therefore, a limited 

number of errors probably exist in the information used to 

construct maps and grids. Those errors are likely a small 

proportion of the entire lithologic record and do not substantially influence the outcomes expressed in the maps and grids. 

In areas of low local drillers’ record density, however, a few 

wells with incorrect lithologic interpretation could locally 

dominate the values represented in the maps and grids.

The user of values appearing in maps and grids of the 

texture-based estimated equivalent of hydraulic conductivity 

and transmissivity should be aware that those are not absolute 

values, nor is the relative difference between the coarse and 

fine end-members, because no aquifer-test evaluations were 

done to derive the estimated values. The range of hydraulic conductivity values used to compute the texture-based 

estimated equivalent of hydraulic conductivity for the entire 

thickness of glacial deposits was selected to be generally representative of values that could be expected for those geologic 

deposits. The values in the maps and grids of texture-based 

estimated equivalent hydraulic conductivity and transmissivity, however, may be re-scaled for applications to areas where 

measured values of aquifer properties are available for scaling 

purposes.
Limitations of the Maps of Hydrogeologic Information 33

Figure 21. Map created during 

this study showing the thickness 

of glacial deposits in the part of 

North Dakota modeled by Thamke 

and others (2014).

Figure 22. Map showing the 

thickness of glacial deposits in 

North Dakota created by Thamke 

and others (2014).

EXPLANATION

Base from U.S. Geological Survey digital data, 1983, 1:100,000 

Albers Equal-Area Conic projection

Standard parallels 20°N and 60°N, central meridian 96°W

160 MILES

160 KILOMETERS

106° 104° 102° 100° 98° 96°

106° 104° 102° 100° 98°

 48°

 46°

 48°

 46°

Thickness of glacial 

deposits, in feet

745

1

0

0 40 80

40 80
34 Maps and Grids of Hydrogeologic Information Created from Standardized Water-Well Drillers’ Records of the Glaciated United States

References Cited

Arihood, L.D., 2009, Processing, analysis, and general evaluation of well-driller records for estimating hydrogeologic 

parameters of the glacial sediments in a ground-water flow 

model of the Lake Michigan Basin: U.S. Geological Survey 

Scientific Investigations Report 2008–5184, 26 p. [Also 

available at http://pubs.usgs.gov/sir/2008/5184/.]

Bayless, E.R., Arihood, L.D., and Sperl, B.J., 2017, Maps and 

grids of hydrogeologic information created from standardized 

water-well drillers’ records of the glaciated United States: 

U.S. Geological Survey data release, https://doi.org/10.5066/

F7BR8QCZ.

Berg, R.C., and Kempton, J.P., 1988, Stack-unit mapping of 

geologic materials in Illinois to a depth of 15 meters: Illinois 

State Geological Survey Circular 542, 4 pl., accessed January 

20, 2015, at http://www.isgs.illinois.edu/publications/c542.

Feinstein, D.T., Hunt, R.J., and Reeves, H.W., 2010, Regional 

groundwater-flow model of the Lake Michigan Basin in support of Great Lakes Basin water availability and use studies: 

U.S. Geological Survey Scientific Investigations Report 

2010–5109, 379 p., accessed March 17, 2015, at http://pubs.

usgs.gov/sir/2010/5109/.

Flint, R.F., Alden, W.C., Apfel, E.T., Bostock, H.S., Capps, 

S.R., Goldthwait, J.W., Gould, L.M., Kay, G.F., Leighton, 

M.M., Leverett, Frank, MacClintock, Paul, Nichols, D.A., 

Norman, H., Thwaites, F.T., White, G.W., and Young, G.A., 

1945, Glacial map of North America: Geological Society of 

America, Special Paper no. 60, scale 1:4,555,000.

Mathey, S.B., ed., 1989, National water information system 

user’s manual, v. 2, chap. 4., Ground-Water Site Inventory 

System: U.S. Geological Survey Open-File Report 89–587, 

281 p.

Maupin, M.A., and Barber, N.L., 2005, Estimated withdrawals from principal aquifers in the United States, 

2000: U.S. Geological Survey Circular 1279, 46 p. 

[Also available at http://pubs.usgs.gov/circ/2005/1279/.]

Miller, J.A., 1999, Ground Water Atlas of the United States—

Introduction and National Summary, chap. A: U.S. Geological Survey Hydrologic Atlas 730, 15 p., accessed January 11, 

2015, at http://pubs.usgs.gov/ha/ha730/ch_a/fullpgPDF.html. 

National Science and Technology Council, 2007, A strategy for 

Federal science and technology to support water availability 

and quality in the United States, 35 p., accessed December 

29, 2014, at https://www.acs.org/content/dam/acsorg/policy/

acsonthehill/briefings/energywaternexus/nstc-09-07-fed-stfor-water-quality.pdf.

Olcott, P.G., 1992, Ground Water Atlas of the United States, Iowa, 

Michigan, Minnesota, Wisconsin: U.S. Geological Survey 

Hydrologic Atlas 730–J, accessed March 17, 2015, at http://

mi.water.usgs.gov/pubs/HA/HA730-J/.

Reilly, T.E., Dennehy, K.F., Alley, W.M., and Cunningham, 

W.L., 2008, Ground-water availability in the United States: 

U.S. Geological Survey Circular 1323, 70 p. [Also available at 

http://pubs.usgs.gov/circ/1323/.]

Soller, D.R., 1986, Preliminary map showing the thickness of 

glacial deposits in Ohio: U.S. Geological Survey Miscellaneous 

Field Studies Map MF–1862, 1 sheet, scale 1:500,000.

Soller, D.R. and P.H. Packard, 1998, Digital representation of a 

map showing the thickness and character of Quaternary sediments in the glaciated United States east of the Rocky Mountains: U.S. Geological Survey Digital Data Series DDS–38, 

superseded by Soller and others, 2012. 

Soller, D.R., Packard, P.H., and Garrity, C.P., 2012, Database for 

USGS map I–1970—Map showing the thickness and character 

of Quaternary sediments in the glaciated United States east of 

the Rocky Mountains: U.S. Geological Survey Data Series 656, 

accessed March 17, 2015, at http://pubs.usgs.gov/ds/656/.

Soller, D.R., and Reheis, M.C., compilers, 2004, Surficial materials in the conterminous United States: U.S. Geological Survey 

Open-File Report 03–275, scale 1:5,000,000, accessed March 

17, 2015, at http://pubs.usgs.gov/of/2003/of03-275/.

Thamke, J.N., LeCain, G.D., Ryter, D.W., Sando, Roy, and Long, 

A.J., 2014, Hydrogeologic framework of the uppermost principal aquifer systems in the Williston and Powder River structural basins, United States and Canada: U.S. Geological Survey 

Scientific Investigations Report 2014–5047, 38 p., accessed 

March 17, 2015, at http://dx.doi.org/10.3133/sir20145047.

U.S. Geological Survey, 1985, National water summary 1984—

Hydrologic events, selected water-quality trends, and groundwater resources: U.S. Geological Survey Water-Supply Paper 

2275, 467 p.

U.S. Geological Survey, 2002, Report to Congress—Concepts 

for national assessment of water availability and use: 

U.S. Geological Survey Circular 1223, 34 p. 

[Also available at http://pubs.usgs.gov/circ/circ1223/.]

U.S. Geological Survey, 2007, Facing tomorrow’s challenges—

U.S. Geological Survey science in the decade 2007–2017: U.S. 

Geological Survey Circular 1309, x + 70 p. [Also available at 

http://pubs.usgs.gov/circ/2007/1309/.]

Warner, K.L., and Arnold, T.L., 2006, Framework for regional 

synthesis of water-quality data for the glacial aquifer system 

in the United States: U.S. Geological Survey Scientific 

Investigations Report 2005–5223, 6 p. [Also available at 

http://pubs.usgs.gov/sir/2005/5223/.]

Bayless and others—Maps and Grids of Hydrogeologic Information Created from Standardized Water-Well Drillers’ Records of the Glaciated United States—Scientific Investigations Report 2015–5105 

ISSN 2328-0328 (online)

https://doi.org/10.3133/sir20155105