Geohydrology, Water Levels and Directions of 

Flow, and Occurrence of Light-Nonaqueous-Phase 

Liquids on Ground Water in Northwestern Indiana 

and the Lake Calumet Area of Northeastern Illinois

U.S. ENVIRONMENTAL PROTECTION AGENCY

Water-Resources Investigations Report 95–4253

Prepared in cooperation with the

U.S. GEOLOGICAL SURVEY
Prepared in cooperation with the

U.S ENVIRONMENTAL PROTECTION AGENCY

Geohydrology, Water Levels and Directions of 

Flow, and Occurrence of Light-Nonaqueous-Phase 

Liquids on Ground Water in Northwestern Indiana 

and the Lake Calumet Area of Northeastern Illinois

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 95–4253

By Robert T. Kay, Richard F. Duwelius, Timothy A. Brown, 

Frederick A. Micke, and Carol A. Witt-Smith

De Kalb, Illinois

Indianapolis, Indiana

1996
U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Gordon P. Eaton, Director

For additional information Copies of this report can be

write to: purchased from:

District Chief U.S. Geological Survey

U.S. Geological Survey Information Services

102 E. Main St., 4th Floor Box 25286, Federal Center

Urbana, IL 61801 Denver, CO 80225-0046

District Chief

U.S. Geological Survey

5957 Lakeside Boulevard

Indianapolis, IN 46278-1996
CONTENTS

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

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

Purpose and Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Previous Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Description of Study Area. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Physiography and Climate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Land Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Geohydrology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Geology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Bedrock Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Unconsolidated Deposits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Hydrology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Surface Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Ground Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Calumet Aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Confining Unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Silurian-Devonian Aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Water Levels and Directions of Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Surface Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Ground Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Water Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Silurian-Devonian Aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Surface-Water and Ground-Water Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Horizontal Hydraulic Gradients and Ground-Water Velocities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Vertical Hydraulic Gradients and Ground-Water Velocities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Occurrence of Light-Nonaqueous-Phase Liquids on Ground Water. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

References Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Appendix 1: Summary of Information and Data Collected During the Synoptic Survey of Wells and 

Surface-Water Stations in Northwestern Indiana and the Lake Calumet Area of 

Northeastern Illinois, June 23–25, 1992 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

PLATE In pocket

Plate 1. Water-table configuration, northwestern Indiana and the Lake Calumet area of northeastern Illinois, 

June 23–25, 1992.

Figures

1-9. Maps showing:

1. Location of study area, political boundaries, large sewer lines, and surface-water bodies, 

northwestern Indiana and the Lake Calumet area of northeastern Illinois . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2. Land use in northwestern Indiana and the Lake Calumet area of northeastern Illinois . . . . . . . . . . . . . . . . 4

3. Surficial geology, northwestern Indiana and the Lake Calumet area of northeastern Illinois. . . . . . . . . . . . 8

4. Location of important topographic features and selected monitoring wells, northwestern 

Indiana and the Lake Calumet area of northeastern Illinois . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Contents III
5. Bedrock geology, northwestern Indiana and the Lake Calumet area of northeastern Illinois. . . . . . . . . . . . 16

6. Bedrock surface, northwestern Indiana and the Lake Calumet area of 

northeastern Illinois . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

7. Thickness of fine-grained unconsolidated deposits, northwestern Indiana and the 

Lake Calumet area of northeastern Illinois . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

8. Thickness of sand deposits, northwestern Indiana and the Lake Calumet area of 

northeastern Illinois . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

IV Contents
CONTENTS

9. Typical directions of surface-water flow, northwestern Indiana and the Lake Calumet 

area of northeastern Illinois . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

10. Graph showing water-level change as a function of time during slug testing, well S65, rising-head 

phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

11. Map showing distribution of horizontal-hydraulic-conductivity values at wells within 30 feet of 

the water table, northwestern Indiana and the Lake Calumet area of northeastern Illinois . . . . . . . . . . . . . . . . . 34

12-14. Graphs showing:

12. Water-level trends in well S297, northwestern Indiana and the Lake Calumet area 

of northeastern Illinois, Oct. 1, 1991–Sept. 30, 1992 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

13. Water-level trends in wells S299 and S277, northwestern Indiana and the Lake Calumet area 

of northeastern Illinois, June 18–25, 1992 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

14. Water-level trends in wells S57, S59, and S64, northwestern Indiana and the Lake Calumet 

area of northeastern Illinois, June 22–24, 1992. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

15-20. Maps showing:

15. Direction of surface-water flow, northwestern Indiana and the Lake Calumet area of 

northeastern Illinois, June 23–25, 1992. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

16. Potentiometric surface of the Silurian-Devonian aquifer, northwestern Indiana and the 

Lake Calumet area of northeastern Illinois, June 23–25, 1992 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

17. Location of transects where horizontal hydraulic gradients along the water table were 

calculated, northwestern Indiana and the Lake Calumet area of northeastern Illinois, 

June 23–25, 1992. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

18. Location of transects where horizontal hydraulic gradients in the Silurian-Devonian aquifer 

were calculated, northwestern Indiana and the Lake Calumet area of northeastern Illinois, 

June 23–25, 1992. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

19. Direction of vertical hydraulic gradient within the Calumet aquifer, northwestern Indiana and 

the Lake Calumet area of northeastern Illinois, June 23–25, 1992 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

20. Location of wells where light-nonaqueous-phase liquids were detected, northwestern 

Indiana and the Lake Calumet area of northeastern Illinois, June 23–25, 1992 . . . . . . . . . . . . . . . . . . . . . . 60

TABLES

1. Horizontal hydraulic conductivities calculated from slug-test data, northwestern Indiana and the Lake 

Calumet area of northeastern Illinois. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2. Calculated horizontal hydraulic gradient and ground-water velocity at the water table along 

transects, northwestern Indiana and the Lake Calumet area of northeastern Illinois . . . . . . . . . . . . . . . . . . . . . . . . . 49

3. Calculated horizontal hydraulic gradient and ground-water velocity in the Silurian-Devonian aquifer 

along transects, northwestern Indiana and the Lake Calumet area of northeastern Illinois. . . . . . . . . . . . . . . . . . . . . 54

4. Calculated vertical hydraulic gradient at selected points, northwestern Indiana and the Lake Calumet 

area of northeastern Illinois . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

5. Light-nonaqueous-phase-liquid thickness (LNAPL), northwestern Indiana and the Lake Calumet area 

of northeastern Illinois, June 23–24, 1992. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

CONVERSION FACTORS AND VERTICAL DATUM

Multiply By To obtain

inch (in.) 25.4 millimeter

foot (ft) 0.3048 meter

Contents V

1Foot per day is the mathematically reduced term of cubic foot per day per square foot of aquifer cross-sectional area.
Geohydrology, Water Levels and Directions of Flow, 

and Occurrence of Light-Nonaqueous-Phase Liquids 

on Ground Water in Northwestern Indiana and the 

Lake Calumet Area of Northeastern Illinois

By Robert T. Kay, Richard F. Duwelius, Timothy A. Brown, Frederick A. Micke, 

and Carol A. Witt-Smith

Introduction 1

Abstract

A study was performed by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to describe the geohydrology and distribution of light-nonaqueousphase liquids in an industrialized area of northwestern Indiana and northeastern Illinois. The 

geologic units of concern underlying this area are 

the carbonates of the Niagaran Series, the Detroit 

River and Traverse Formations; the Antrim Shale; 

and sands, silts, and clays of Quaternary age. 

The hydrologic units of concern are surface water, 

the Calumet aquifer, the confining unit, and the 

Silurian-Devonian aquifer.

Water levels collected in June 1992 indicate 

that the water-table configuration generally is a 

subdued reflection of topography. Recharge 

from landfill leachate and ponded water, discharge to sewers, and pumping also affect the 

water-table configuration. A depression in the 

potentiometric surface of the Silurian-Devonian 

aquifer results from pumping. Light-nonaqueous-phase liquids were detected near petroleum 

handling, industrial and waste-disposal facilities.

Horizontal ground-water velocity at the 

water table in the confining unit ranged from 

1

U.S. Environmental Protection Agency, Region 5, 

Chicago, Illinois.

4.4×10−4 to 1.0×10−3 feet per day. Horizontal 

ground-water velocity in the Calumet and 

Silurian-Devonian aquifers ranged from 

1.0×10−2

 to 3.4×10−1 and from 1.4×10−2 to 

2.9×10−2

 feet per day, respectively.

Vertical hydraulic gradients indicate generally downward flow from the Calumet aquifer 

into the confining unit, then into the SilurianDevonian aquifer. Calculated vertical groundwater velocity through the weathered and 

unweathered parts of the confining unit are 

3.8×10−2 and 1.5×10−3 feet per day, respectively.

INTRODUCTION

In June 1992, the U.S. Geological Survey 

(USGS), in cooperation with the U.S. Environmental 

Protection Agency (USEPA), began a study of the geohydrology and distribution of light-nonaqueous-phase 

liquids (LNAPL’s) in an urban and industrial area of 

northwestern Indiana and northeastern Illinois (fig. 

1). Industry in this area includes several steel mills, 

petroleum refineries, petroleum-tank farms, forging 

and foundry plants, and chemical manufacturing facilities (fig. 2). In addition, 2 hazardous-waste incinerators, at least 11 sanitary landfills, numerous 

uncontrolled waste-disposal sites, and about 80 

accidental-spill sites are located within this area. 

Contaminants from these and other sources have 

leached to ground water and surface water 

By Robert T. Kay, Richard F. Duwelius, Timothy A. Brown, Frederick A. Micke1,

and Carol A. Witt-Smith1
2 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 1. Location of study area, political boundaries, large sewer lines, and surface-water bodies, northwestern Indiana and the 

Lake Calumet area of northeastern Illinois. (Sewers shown in Indiana are modified from Fenelon and Watson, 1993. Sewers 

shown in Illinois are modified from Keifer and Associates, 1976.) Crawford Avenue

80th Street

Calumet Sag

Channel

Little

Little

Calumet

Calumet

River

River

Wolf 

Lake

Lake Michigan

Calumet 

Harbor

Indiana

Harbor

Cook CountyLake County

ILLINOISINDIANA

Lake

George

Indiana

Harbor Canal

Grand

Blue

Island

Whiting

Hammond

East Chicago

C h i c a g o

87 ̊ 40’

41 ̊ 40’

41 ̊ 35’

35’ 30’ 25’

Lake

Calumet

80 94

94

90

80

94

57

294

294

EXPLANATION

SEWER LINES

POLITICAL BOUNDARY

Calumet

River

Buffington

Harbor
Introduction 3

Figure 1. Continued.

0 1 2 3 4 5 MILES

0 1 234 5 KILOMETERS

Illinois Indiana

Study

Area

Calumet River

Gary

Harbor

Burns 

Harbor

River

Little

Grand Calumet 

Lagoons

Ogden

Dunes Lake County Porter County

G a r y

Mineral Springs Rd.

Lake Michigan

20’ 15’ 10’ 87 ̊ 05’

90

90

Calumet

65
4 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 2. Land use in northwestern Indiana and the Lake Calumet area of northeastern Illinois.

87 ̊ 40’

41 ̊ 40’

41 ̊ 35’

35’ 30’ 25’

Grand

80

94

80

90

57

294

ILLINOISINDIANA

Cook CountyLake County

Canal Harbor Indiana

Calumet

Little

Channel

Calumet Sag

Little

Calumet

Calumet

Calumet

River

River

River

Lake

George

Wolf 

Lake

Lake

Calumet

Lake Michigan

Thornton

Quarry

Calumet 

Sewage

Treatment 

Plant

Crawford Avenue

80th Street

EXPLANATION

STEEL INDUSTRY

INDUSTRY—Other than steel or petrochemical

PETROCHEMICAL INDUSTRY

RESIDENTIAL OR OPEN WATER

WASTE TREATMENT OR DISPOSAL

NATURAL

94
Introduction 5

Figure 2. Continued.

20’ 15’ 10’ 87 ̊ 05’

River

Calumet

Calumet River

Little

0 1 2 3 4 5 MILES

0 1 234 5 KILOMETERS

Lake Michigan

Lake County

Porter County

Illinois Indiana

Study

Area

90

90

65
6 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

(U.S. Department of Health, Education and Welfare, 

1965; HydroQual, Inc., 1985; Fenelon and Watson, 

1993).

The study was designed to describe the geology 

and hydrology in this area, determine surface-waterflow directions, determine ground-water-flow directions within and between the shallow hydraulic units, 

characterize the interaction between surface water and 

ground water, and to obtain a preliminary estimate of 

the location and extent of LNAPL’s on the water table. 

This information will be used to identify areas needing 

additional study.

The study was divided into two major components: compilation and analysis of the existing 

geologic, hydrologic, and water-quality data; and 

collection of LNAPL and static water-level measurements during a 2-day synoptic period. Geologic, 

hydrologic, and water-quality data were compiled 

and analyzed to assess hydraulic and water-quality 

conditions and to plan the synoptic water-level survey. 

Static water-level measurements were collected to 

determine the directions of flow within and between 

the hydraulic units and to provide a better understanding of the factors that affect surface-water and groundwater flow. Measurements of LNAPL’s in observation wells were collected to obtain a preliminary 

estimate of the location and extent of LNAPL’s.

Purpose and Scope

This report describes the results of an investigation designed to characterize the geohydrology and to 

determine the location and extent of LNAPL’s in an 

industrialized area in northwestern Indiana and northeastern Illinois. In addition to a description of the 

geology and hydrology of the study area, the results 

of an area-wide synoptic water-level survey are presented. The report identifies the direction of surfacewater flow, the direction and velocity of vertical and 

horizontal ground-water flow within the hydraulic 

units of concern, and the nature of the surface-water 

and ground-water interaction in the study area during 

the synoptic water-level survey. The location and 

thickness of LNAPL’s measured on the water table 

during the synoptic water-level survey also are presented.

Previous Work

Concerns about environmental problems have 

resulted in several studies of the hydrology and 

ground-water quality within the study area. These 

investigations have focused on Lake Calumet in 

Illinois and the Grand Calumet River near the Indiana 

Harbor Canal in Indiana (fig. 1). These areas have 

experienced the most severe environmental degradation.

One of the first investigations to provide a 

framework under which the environmental effects 

of industrial and waste-disposal activities could be 

assessed was a compilation of industrial wastedisposal activities in the Lake Calumet area from 

1869 through 1970 (Colten, 1985). It is assumed 

that the history of industrial-waste disposal in Indiana 

is similar. Colten divided industrial activity and 

waste-disposal practices into three phases on the basis 

of the legal and technological framework within which 

disposal took place.

The first phase of waste-disposal activities in 

the Lake Calumet area occurred from 1869 to 1921 

and was characterized by the discharge of untreated 

liquid and particulate wastes to surface-water bodies, 

primarily the Calumet and Little Calumet Rivers 

(fig. 1). The liquid wastes contained hundreds of 

tons of phenols, cyanide, lubricating oils, sulfuric acid, 

and iron sulfate (Colten, 1985, p. 27, 45, 63). Solid 

wastes, especially slag and fly ash, typically were 

dumped onto vacant land and into lakes and wetlands 

as fill.

The second phase of waste-disposal activity 

identified by Colten occurred from 1922 to 1940 and 

was characterized by the opening of the Calumet Sag 

Channel and construction of the Calumet Sewage 

Treatment Plant (fig. 2). Opening of the Calumet 

Sag Channel diverted flow in the Calumet River 

system from Lake Michigan to the Illinois River 

system under most hydraulic conditions. This diversion greatly reduced the amount of contamination in 

Lake Michigan, the principal source of water for 

industrial and municipal supply in northeastern Illinois 

and northwestern Indiana. Construction of the 

Calumet Sewage Treatment Plant resulted in effluent 

from a few of the industrial facilities receiving some 

treatment before being discharged to surface water.

The third phase of waste-disposal activities 

occurred from 1940 to 1970 and was characterized 

by a shift from disposal of industrial wastes in water to 

disposal on land. Municipal and construction refuse, 

as well as industrial waste, was buried in municipal 

landfills. In addition to slag and ash, which had 

always been disposed of in this manner, dredge spoil 
Previous Work 7

and sludges from wastewater-treatment facilities were 

dumped into nearby wetlands during this period. An 

increasing number of industrial facilities also began 

treating wastewater before releasing the effluent to the 

rivers.

The shift from water to land disposal of wastes, 

environmental regulations requiring wastewater treatment, and a decline in industrial activity lessened the 

effect of waste disposal on the Calumet River system 

since 1970 (HydroQual, Inc., 1985, p. S–3). However, significant environmental problems associated 

with surface-water and ground-water degradation still 

remain.

The disposal of large quantities of municipal and 

industrial wastes in lakes, wetlands, and on the land 

surface affects ground-water quality at several industrial and waste-disposal sites, in addition to affecting 

the viability of the lakes and wetlands. The effect of 

land disposal is particularly severe at Lake Calumet, 

where much of the lake area in 1869 had been filled 

with municipal and industrial waste by 1994 (fig. 3). 

Crushed and hot-poured slag also has been used as fill 

to create large areas of “made” land along the shores 

of Lake Michigan, Wolf Lake, and Lake George.

Colten (1985, appendix A) identified sites of 

waste disposal and industrial activities in the Lake 

Calumet area from 1869 to 1970 and evaluated each 

site for the risk it posed to human health and the 

environment. It was concluded that a number of 

these sites had the potential to adversely affect human 

health and the environment but that additional information was needed to accurately characterize that 

effect.

The Illinois Environmental Protection Agency 

(IEPA) drilled several borings in the Lake Calumet 

area and analyzed the soils and ground water from the 

borings for a number of compounds (Illinois Environmental Protection Agency, 1986) to determine the 

effect of industrial and waste-disposal activities on 

shallow ground-water quality in the Lake Calumet 

area. Concentrations of several metals above background levels were detected in some of the soil 

samples. Several volatile and semivolatile organic 

compounds were detected in ground-water samples 

collected at some industrial sites.

Expanding on the work of the IEPA, the Illinois 

State Water Survey (ISWS) performed a preliminary 

assessment of the hydrology and ground-water quality 

in the Lake Calumet area (Cravens and Zahn, 1990). 

Cravens and Zahn noted that shallow ground-water 

flow is intrinsically connected to flow in the surfacewater bodies but that delineation of the shallow 

ground-water-flow system was difficult because of 

the sparse data then available. The report also noted 

that flow in the uppermost bedrock aquifer is generally 

toward Lake Michigan, though it has been disrupted 

by excavations in the bedrock for the Metropolitan 

Water Reclamation District of Greater Chicago’s 

Tunnel and Reservoir Plan (TARP) storm-drainage 

tunnels. These tunnels are about 300 ft below the 

land surface and are used to transport combinedsewer-overflow water to treatment facilities. Analysis of ground-water-quality data collected by the 

ISWS and a number of government agencies and 

private organizations led to the conclusion that, 

although organic compounds and metals were detected 

in the shallow ground water near many of the industrial and waste-disposal facilities, no evidence of 

widespread contamination of the shallow ground 

water in the Lake Calumet area was found. Analysis 

of the ground-water-quality data also led to the conclusion that the small amounts of contamination detected 

in the uppermost bedrock aquifer could be attributed 

to leakage from the surface or shallow ground water to 

the bedrock aquifer around improperly sealed wells or 

borings, not to transport through geologic material.

The ISWS is currently (1994) investigating the 

hydrogeology and ground-water quality in the shallow 

ground-water-flow system near Lake Calumet and 

Wolf Lake. High concentrations of metals and volatile organic compounds were detected in ground-water 

samples collected in several shallow wells during this 

current study (Cravens and Roadcap, 1991, p. 13, 14; 

Roadcap and Kelly, 1994, p. 39, 40). Slag fill was 

assumed to be the source of most of the metals.

A detailed study of the shallow ground-waterflow system in the Indiana part of the study area was 

done by the USGS in 1985–86 (Watson and others, 

1989). The report notes that the water-table configuration in this area mirrors surface topography except 

near large sewers and pumping centers where local 

depressions are present. Analysis of surface-water 

and ground-water levels during this study indicates 

that ground water typically discharges to the major 

surface-water bodies and small ditches, though flow 

reversals are common.

A follow-up study of the hydrology and groundwater quality in the shallow ground-water system in 

northwestern Indiana was done by the USGS in 

1988–89 (Fenelon and Watson, 1993). Ground-water 
8 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 3. Surficial geology, northwestern Indiana and the Lake Calumet area of northeastern Illinois. (From Schneider and 

Keller, 1970.)

Grand

River

MADE AND MODIFIED LAND—Artificial fill and 

land substantially modified by the removal of

unconsolidated deposits. Many small areas 

not mapped

MUCK OR SILT OVER SAND AND GRAVEL— 

Outwash sand and gravel overlain in places 

by thin lacustrine, paludal or alluvial deposits 

of peat, muck, or clay. Martinsville Formation 

over outwash facies of Atherton Formation in 

Indiana, glacial sluiceway in Illinois

SAND AND SOME SILT—Dune deposits. 

Dune facies of Atherton Formation 

in Indiana, Parkland Sand in Illinois

TILL—End moraine deposit. Lagro Formation 

in Indiana, Wadsworth Till in Illinois

TILL—Wave-scoured lake-bottom till. Lagro 

Formation in Indiana, Wadsworth Till in Illinois

DOLOMITE—Marine deposit. Niagaran Series

EXPLANATION

Lake Michigan

87 ̊ 40’

41 ̊ 40’

41 ̊ 35’

35’ 30’ 25’

Blue Island

Stony

Island

Thornton

Quarry River Cook County Lake County ILLINOIS INDIANA

Calumet

Little

Indiana

Canal Harbor

Lake

George

Wolf 

Lake

Lake

Calumet

Calumet

Little

Channel

Calumet Sag

SILURIAN

WISCONSINAN

WISCONSINAN AND RECENT

RECENT

M

GS

D D

P D

P

P

W

LP

S

C

D

LP

D

S

D

M

D

M

GS

P

W

LP

S

M

C

SAND AND GRAVEL—Beach and shoreline 

deposits in bars, spits, and beaches. 

Some dune sand. Atherton Formation

in Indiana, Dolton Member in Illinois

D

CLAY AND SILT—Lacustrine deposits. 

Lacustrine facies of Atherton Formation 

in Indiana, Carmi Member in Illinois

C

Buffington

Harbor
Previous Work 9

Figure 3. Continued.

Calumet River

G a r y

Little

Lake County

Porter County

River

Calumet

Illinois Indiana

Study

Area

20’ 15’ 10’ 87 ̊ 05’

0 1 2 3 4 5 MILES

0 1 234 5 KILOMETERS

Gary

Harbor

Burns 

Harbor

Lake Michigan

P

C

M

D

D

D M

D

P

P

C

GS

M
10 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

quality is described as being poorest at the steel and 

petrochemical facilities, moderate near light industrial 

and commercial areas, and best in residential and park 

areas. It was estimated that ground water may contribute more than 10 percent of the total chemical load 

of ammonia, chromium, and cyanide to the Grand 

Calumet River.

Numerous geotechnical and environmental 

investigations at specific industrial and waste-disposal 

sites also have been done. Results indicate environmental problems at several sites, many of which are 

adjacent. These site-specific investigations generally 

provide a detailed understanding of the geohydrology 

at a specific site, but not of the hydrogeologic relation 

between adjacent sites and between a site and the area 

as a whole.

Acknowledgments

The authors extend their thanks to the numerous 

Federal, State, and municipal agencies and corporations that provided hydrogeologic information and (or) 

access to the data-collection points. In addition, the 

authors would like to thank those persons from the 

USEPA, Indiana Department of Environmental Management, and Metcalf and Eddy, Inc., who helped 

collect the water-level data for this study. Finally, 

Doug Yeskis of the USEPA and Jeff Miller of Metcalf 

and Eddy, Inc., are thanked for their assistance in the 

planning and execution of this study.

DESCRIPTION OF STUDY AREA

The study area is located in the Calumet area 

of northwestern Indiana and northeastern Illinois and 

includes parts of Porter and Lake Counties in Indiana 

and Cook County in Illinois (fig. 1). The study area 

is bounded by the southern limit of the Little Calumet 

River and Interstates 80 and 94 to the south, Crawford 

Avenue to the west, Mineral Springs Road to the east, 

and 80th Street and Lake Michigan to the north.

Physiography and Climate

The study area is in the Eastern Lake Section of 

the Central Lowland physiographic province defined 

by Fenneman (1938). The Indiana part is in the 

Calumet Lacustrine Plain subdivision of the Northern 

Moraine and Lake Region defined by the Indiana 

Geological Survey (IGS) (Malott, 1922, p. 113; 

Schneider, 1966, p. 50). The Calumet Lacustrine 

Plain extends westward into Illinois where it is called 

the Chicago Lake Plain subsection of the Great Lakes 

Section of the Central Lowland physiographic province as defined by the Illinois State Geological Survey 

(ISGS) (Leighton and others, 1948, p. 21).

Glacial, lacustrine, paludal, and aeolian processes have produced the physiographic characteristics 

of this area. Near the end of the last glacial period, 

glacial ice moved southward along the basin currently 

occupied by Lake Michigan. The ice stopped just 

south of the study area, forming the Valparaiso 

Morainic System (Bretz, 1939, p. 45–59, fig. 37). 

The glacier receded and advanced north of the 

Valparaiso Morainic System several times, forming 

several end moraines in Illinois and Indiana. As the 

glacier receded to the north, Lake Chicago formed 

between the glacier and the moraines (Wayne, 1966, 

p. 36). Lake Chicago and its successors rose and fell 

repeatedly, producing physiographic features whose 

locations are controlled, in part, by the location of the 

shoreline during the fluctuating lake stages.

Erosional and depositional processes associated 

with the advance and retreat of the glaciers and the 

fluctuations in lake stage resulted in a generally flat 

land surface that slopes gently toward Lake Michigan. 

The flat surface of the lake plain is broken up by a 

number of low beach ridges, morainal headlands and 

islands, and a large glacial drainway (fig. 4). Most 

of the area is swampy and poorly drained under natural conditions, and the location of surface-water bodies 

is primarily affected by the location of the beach 

ridges. The land-surface altitude on the flat part of 

the lake plain ranges from about 590 ft above sea level 

west of Lake Calumet to about 581 ft above sea level 

along the shore of Lake Michigan.

The largest of the beach ridges is the Toleston 

Beach Ridge, which separates the Grand Calumet and 

Little Calumet Rivers. Rising between 10 and 15 ft 

above the lake plain, the Toleston Beach Ridge is the 

most lakeward of the dune and beach complexes produced by shoreline deposition during a period of 

higher lake stage (Thompson, 1989, p. 711). Numerous smaller sandy ridges, including dunes, spits, and 

bars, also are present. Many of the ridges that were 

once present have been leveled or removed by quarrying in the past century. These ridges roughly parallel 

Lake Michigan.
Geohydrology 11

The most prominent dune deposits in the 

study area are located at the Indiana Dunes National 

Lakeshore (IDNL) (fig. 4). Topographic relief at 

the IDNL varies from near lake level (581 ft above 

sea level) to as high as 750 ft above sea level. The 

dune crests are the highest natural features in the 

study area.

Blue Island is a morainal island near the western 

edge of the study area (fig. 4). Blue Island trends 

north-south with a maximum elevation of about 670 ft 

above sea level.

Stony Island is a bedrock outcrop north of Lake 

Calumet (fig. 4). About 1 mi long and a quarter of 

a mile in width, Stony Island is about 20 ft above the 

lake plain and trends east-west.

The principal outlet for Lake Chicago was 

through a glacial sluiceway, or outwash channel, 

between the Toleston Beach Ridge and Blue Island 

(fig. 4) (Malott, 1922, p. 152; Bretz, 1939, p. 59; 

Willman, 1971, p. 55), although the lake drained to 

the east during periods of low lake stage (Fullerton, 

1980). Erosion along the sluiceway formed a topographic depression which is the current location of 

the Calumet Sag Channel.

The climate in this area is classified as temperate 

continental, with a mean annual temperature of about 

10°C and a mean annual precipitation of 35.7 in. 

(National Oceanic and Atmospheric Administration, 

1991, 1992b). More than half of the average annual 

precipitation falls from April 1 through August 31. 

Although large variations in precipitation and temperature may occur in any year, summers generally are 

hot and humid, whereas winters are cold. Lake 

Michigan has a moderating local effect on temperature.

The National Oceanic and Atmospheric Administration (NOAA) maintained two weather stations in 

the study area—one at the Gary Regional Airport, and 

the other at Ogden Dunes, Ind. (fig. 4). From 1951 to 

1980, the mean monthly temperature at these stations 

varied from about –5°C in January to about 23°C in 

July, and the mean monthly precipitation varied from 

1.5 in. in February to 4.0 in. in June. Precipitation at 

Ogden Dunes was slightly larger than at the Gary 

airport (National Oceanic and Atmospheric Administration, 1982).

From June 1991 to June 1992, the 12-month 

period before the start of the synoptic water-level 

survey, the amount of precipitation measured at a 

NOAA station at the University of Chicago, about 

1 mi north of the northern boundary of the study area, 

was 13 in. below normal (National Oceanic and 

Atmospheric Administration, 1991, 1992b). The 

University of Chicago station was used because the 

Gary airport and Ogden Dunes stations were not in 

operation from June 1991 to June 1992.

An estimated 70 percent of the average annual 

precipitation on this area is returned to the atmosphere 

by evapotranspiration (Mades, 1987, p. 13). Based 

on this percentage, average annual precipitation available for recharge to ground water is no greater than 

10.7 in. More than three-quarters of all evapotranspiration occurs during the growing season (U.S. Geological Survey, 1970, p. 96). During the growing 

season, evapotranspiration normally exceeds precipitation by about 1 to 2 in. and depletes available soil 

moisture. During the nongrowing season, precipitation generally exceeds evapotranspiration by about 

11 in. and replenishes soil moisture and recharges 

ground water. The mean annual lake evaporation 

is 29.5 in. or about 83 percent of the average annual 

precipitation.

Land Use

Land use in the study area is primarily residential and industrial (fig. 2). Large tracts of open water, 

natural land, and land for the treatment and disposal of 

wastes also are present. Much of the land along Lake 

Michigan and the Calumet River is or was used for 

steel production. Land used by the petrochemical 

industry for tank farms and petroleum refining is 

located south and west of the steel mills in Indiana 

and at scattered locations along the Grand Calumet 

River, the Calumet Sag Channel, and Lake Calumet 

in Illinois. A variety of other industrial activities, 

including automobile assembly, scrap processing, 

and chemical manufacturing take place in this area.

Several landfills, wastewater-treatment plants, and 

unregulated waste-disposal facilities are present near 

Lake Calumet.

GEOHYDROLOGY

The geology and hydrology of the study area 

have been described by a number of investigators 

(Bretz, 1939, 1955; Rosenshein and Hunn, 1968; 

Willman, 1971; Hartke and others, 1975; Watson 

and others, 1989; Cravens and Zahn, 1990). Their 
12 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 4. Location of important topographic features and selected monitoring wells, northwestern Indiana and the 

Lake Calumet area of northeastern Illinois.

94

94

90

57

80

80 94

294

80th Street

Calumet Sag

Channel

Little

Little

Calumet

Calumet

River

River

Wolf 

Lake

Lake Michigan

Cook County

Lake County

ILLINOIS

INDIANA

Lake

George

Indiana

Harbor

Grand

Blue

Island

Hammond

30’

41 ̊ 40’

41 ̊ 35’

87 ̊ 40’ 35’ 25’

Lake

Calumet

Glacial

Sluiceway

Stony

Island

S64

S277 S57

S59

S297

Thornton 

Quarry

Canal

Calumet

River

Crawford Avenue

EXPLANATION

MONITORING WELL LOCATION AND NAME—

Site of well in which background 

water-level data were collected

WEATHER STATION

S64

T

o l

e s t o n B e a c h R i d g e

Gary Regional

Airport
Geohydrology 13

Figure 4. Continued.

0 1 2 3 4 5 MILES

0 1 234 5 KILOMETERS

Calumet River

Indiana Dunes 

National Lakeshore Ogden Dunes Lake County County Porter

Little

Calumet

River

S299

Lake Michigan

Toleston Beach Ridge

Illinois Indiana

Study

Area

20’ 15’ 10’ 87 ̊ 05’

65

90

90
14 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

descriptions, in combination with analysis of lithologic 

and hydrologic data compiled during this and previous 

studies, form the basis for the discussion of the geology and hydrology.

Geology

The geologic deposits of concern to this investigation are bedrock deposits of Silurian and Devonian 

age and unconsolidated deposits of Quaternary age. 

The stratigraphic nomenclature used in this report is 

that of the ISGS (Willman and Frye, 1970, p. 70–75; 

Willman and others, 1975, p. 100–104) and the IGS 

(Shaver and others, 1970, 1986). Their usage does 

not necessarily follow the usage of the USGS.

Bedrock Deposits

The bedrock in this area is comprised primarily 

of dolomite, limestone, and shale. The bedrock strata 

are essentially horizontal, except in the northeastern 

part of the study area where the bedrock strata dip 

slightly toward the northeast.

The oldest bedrock deposits of concern to this 

investigation are Silurian dolomites and limestones of 

the Niagaran Series. The Niagaran carbonates are up 

to 300 ft thick in the study area and are present at the 

bedrock surface in Illinois and western Indiana (fig. 5). 

These deposits are known as the Wabash Formation 

in Indiana (Shaver and others, 1986, p. 162) and the 

Racine Dolomite in Illinois (Willman, 1971, p. 29–30).

The Niagaran carbonates are characterized by 

large reefs, two of which are present at the land surface 

at Stony Island and Thornton Quarry (fig. 3). 

The reefs are composed of a vuggy dolomite with 

traces of argillaceous material or sand grains. A solid 

petroleum residue called asphaltum is present in some 

of the vugs in the reefs (Willman, 1971, p. 30). Beds 

on the flanks of the reefs commonly dip radially away 

from the massive to irregularly bedded reef core. 

Away from the reefs, the Niagaran deposits consist 

of dense, cherty, argillaceous dolomite and limestone 

with localized lenses of green shale.

The Niagaran carbonates contain an irregularly 

distributed network of vertical fractures with a major 

trend at N. 47° W. and a minor trend at about N. 57° E. 

(Zeizel and others, 1962; Foote, 1982). Fractures 

are generally more abundant near the bedrock surface, 

where the bedrock is more weathered, and decrease 

in number with depth as the rock becomes more 

competent (Suter and others, 1959, p. 9). The reef 

deposits tend to have fewer fractures than the interreef 

deposits.

In addition to fractures, several vertical faults 

have been identified in the bedrock in Illinois (fig. 5). 

Most of these faults are oriented northwest to southeast and are 2–3 mi long. Faulting has offset the 

bedrock strata as much as 30 ft, but displacement does 

not extend upward into the unconsolidated materials 

(Keifer and Associates, 1976, p. 27–36). The extent 

of faulting in Indiana is unknown.

Lower to middle Devonian deposits of the 

Detroit River and Traverse Formations unconformably 

overlie the Niagaran Series in parts of Indiana (fig. 5). 

The Detroit River Formation varies from a light 

colored, fine-grained, sandy dolomite near the base 

of the formation to a gray to dark brown dolomite and 

limestone with thin to massive beds of gypsum and 

anhydrite in the upper part of the deposit (Shaver and 

others, 1986, p. 35–37). The Traverse Formation 

unconformably overlies the Detroit River Formation. 

The Traverse Formation consists of brown to gray, 

fine-to-coarse grained limestone to dolomitic limestone (Shaver and others, 1986, p. 156). Both 

formations thicken toward the northeast.

The Upper Devonian Antrim Shale is the youngest bedrock unit in the study area and unconformably 

overlies the Traverse Formation in Porter County 

(fig. 5). The Antrim Shale consists of brown to 

black, noncalcareous shale with gray calcareous shale 

or limestone in the lower part of the formation (Shaver 

and others, 1986, p. 5).

The bedrock surface, based on lithologic logs 

compiled from throughout the study area, has more 

than 175 ft of relief (fig. 6). Bedrock highs are 

present at Stony Island and Thornton Quarry. 

Bedrock lows are present near Burns Harbor, Gary 

Harbor, the Indiana Harbor Canal, and immediately 

east of Lake Calumet. Bedrock highs at Stony Island 

and Thornton Quarry are attributed to the greater 

resistance of the reef deposits in these areas to erosion 

(Bretz, 1939, p. 66). The bedrock valleys may mark 

the paths of preglacial drainage that flowed north and 

east from a surface-water divide (Bretz, 1939, p. 92)

Unconsolidated Deposits

Most of the unconsolidated sediments were 

originally deposited by glaciers or were deposited as 

lake-bottom and near-shore deposits of Lake Chicago 
Geology 15

and its successors (Willman, 1971, p. 38–51; Hartke 

and others, 1975, p. 7). Glacial and lacustrine processes resulted in the deposition of three types of 

materials: glacial till, lacustrine silt and clay, and 

fluvial and aeolian sand. Small amounts of muck, 

peat, and fine gravel were deposited in localized areas 

(fig. 3). The total thickness of the unconsolidated 

sediments ranges from less than 1 ft in the vicinity of 

Thornton Quarry to over 225 ft east of Burns Harbor 

(figs. 7 and 8).

In most of the area, the bedrock is overlain by 

dense, lenticular bodies of poorly sorted gravel, sand, 

and silt. These deposits are informally called the 

Lemont Drift in Illinois (Cravens and Zahn, 1990, 

p. 15). The exact age of these deposits is unknown, 

but they appear to have been eroded and weathered 

before being covered by sediments during subsequent 

glacial advances.

The Lemont Drift and similar deposits in 

Indiana are overlain by a gray clayey till. The till 

is very hard and tends to become denser and more 

consolidated with depth, probably because of compression by the ice sheets during the glacial advances. 

This till is known as the Wadsworth Till Member of 

the Wedron Formation in Illinois (Willman, 1971, 

p. 46) and composes part of the Lagro Formation in 

Indiana (Shaver and others, 1970, p. 87–88). The 

Wadsworth Till Member is present at the land surface 

at Blue Island (fig. 3).

The Wadsworth Till Member is overlain by 

sand, silt, and clay deposits known as the Equality 

Formation in Illinois (Willman, 1971, p. 49) and the 

Atherton Formation in Indiana (Shaver and others, 

1970, p. 7). These deposits are the surficial geologic 

unit in most of the study area (fig. 3). The 

Wadsworth-Equality boundary represents a transition 

from deposition dominated by glacial processes to 

deposition dominated by lacustrine processes.

The Equality Formation is subdivided by the 

ISGS into the Carmi and Dolton Members. The 

Carmi Member is equivalent to the lacustrine facies 

of the Atherton Formation (Schneider and Keller, 

1970; Willman, 1971, pl. 1). The Dolton Member is 

equivalent to the beach and shoreline deposits of the 

Atherton Formation (Schneider and Keller, 1970; 

Willman, 1971, pl. 1). These units grade laterally 

into each other and are superimposed in some areas.

The Carmi Member is comprised predominantly 

of silt and clay with localized peat beds. These are 

generally well bedded or laminated lake deposits and 

are at the land surface in much of the area around Lake 

Calumet and parts of the Little Calumet River (fig. 3). 

The Carmi Member underlies the Dolton Member near 

the confluence of the Calumet, Grand Calumet, and 

Little Calumet Rivers (Woodward-Clyde Consultants, 

1984, fig. E–3) and in most of the Indiana part of the 

study area (Watson and others, 1989, p. 18).

The Dolton Member is predominantly sand but 

contains thin, discontinuous beds of muck and peat as 

well as pebbly sand and gravel. These sands consist 

of shore and shallow-water lake deposits, commonly 

found in ridges defining the former locations of spits 

and beaches. The Dolton Member is at the land 

surface in much of the area east of the Calumet River 

and at sporadic locations west of Lake Calumet 

(fig. 3). The Dolton Member underlies the Carmi 

Member in much of the area from the State line to the 

eastern shore of Lake Calumet and along parts of the 

Little Calumet River (compare fig. 3 and fig. 8).

The Parkland Sand is a well sorted, mediumgrained sand that was blown from the glacial outwash 

and beach deposits into dunes and sheet-like deposits 

around the dunes (Willman, 1971, p. 50). The Parkland Sand is found along the Toleston Beach Ridge, 

the western flank of Blue Island, and at the Indiana 

Dunes National Lakeshore (figs. 3, 4). The Parkland 

Sand is equivalent to the dune facies of the Atherton 

Formation in Indiana (Shaver and others, 1970, p. 7).

The glacial sluiceway eroded into, and in some 

areas through, the till along the path of the Calumet 

Sag Channel and was filled with fluvial sand and 

gravel deposits (fig. 3). These sands and gravels 

have a maximum thickness of about 25 ft (fig. 8).

Glacial outwash deposits of sand and gravel also are 

along the path of the Little Calumet River in parts 

of Indiana (fig. 3). Outwash and sluiceway deposits 

are part of the Martinsville Formation described by 

Shaver and others (1970, p. 107).

With the exception of the area mapped as 

Wadsworth Till at Blue Island, which was never 

submerged, the top of the Wadsworth Till Member 

was reworked by wave erosion throughout the study 

area (fig. 3) (Willman, 1971, pl. 1; Watson and 

others, 1989, p. 18). Though deposition from wave 

erosion was minimal, the upper surface of the 

Wadsworth Till Member was modified. Those 

areas where the Wadsworth Till Member was submerged and not covered by subsequent sediment 

deposition are mapped as wave-scoured lake-bottom 

till (fig. 3), hereafter referred to as the Lake-Plain 
16 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 5. Bedrock geology, northwestern Indiana and the Lake Calumet area of northeastern Illinois. (Modified from Schneider 

and Keller, 1970.)

80th Street

Calumet Sag

Channel

Little

Little

Calumet

Calumet

Calumet

Calumet

River

River

River

Wolf 

Lake

Lake Michigan

Cook CountyLake County

ILLINOIS

INDIANA

Lake

George

Indiana

Harbor Canal

Grand

87 ̊ 40’

41 ̊ 40’

41 ̊ 35’

35’ 30’ 25’

Lake

Calumet

80 94

94

80

94

90

90

57

294

294

U

U

U

U

U

U

U

U

U

U

D

D

D

D

D D

D

D

D

D

EXPLANATION

Crawford Avenue

DEVONIAN

SILURIAN

ANTRIM SHALE—Brown to black and gray shale with limestone in lower part

TRAVERSE AND DETROIT RIVER FORMATIONS—Predominately 

limestone and dolomite

NIAGARAN SERIES—Predominately dolomite

FAULT—Approximately located. U indicates upthrown side. D indicates 

downthrown side. No fault data available for Indiana

U

D

S1

S1

D2

D1
Geology 17

Figure 5. Continued.

River

Calumet

Calumet River

Little

Lake Michigan

20’ 15’ 10’ 87 ̊ 05’

0 1 2 3 4 5 MILES

0 1 234 5 KILOMETERS

Illinois Indiana

Study

Area

90

94

90

D 65 1

D1

D2

Lake County

Porter County
18 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 6. Bedrock surface, northwestern Indiana and the Lake Calumet area of northeastern Illinois.

Calumet Sag

Channel

Little

Little

Calumet

Calumet

River

River

Wolf 

Lake

Lake Michigan

Cook CountyLake County

ILLINOISINDIANA

Lake

George

Indiana

Harbor

Grand

87 ̊ 40’

41 ̊ 40’

41 ̊ 35’

35’ 30’ 25’

Lake

Calumet

Canal

525 575

550

525

550

500 425

475

450

450

475

500

500

600

575

550

575

600

550

525

500

500

Thornton 

Quarry

EXPLANATION

BEDROCK-SURFACE CONTOUR—

Shows altitude of bedrock surface. 

Dashed where approximate. 

Contour interval 25 feet. 

Datum is sea level

450

Stony Island

525

475

Buffington

Harbor

Calumet

River

475
Geology 19

Figure 6. Continued.

0 1 2 3 4 5 MILES

0 1 234 5 KILOMETERS

Illinois Indiana

Study

Area

Calumet River

Gary

Harbor

Burns 

Harbor

Calumet

River

Little

Lake County

Porter County

Lake Michigan

20’ 15’ 10’ 87 ̊ 05’

425

450

475

500

525

450

425

450

425

475

425

Map compiled and drawn by T.K. Greeman and 

D.A. Stewart, U.S. Geological Survey

475
20 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 7. Thickness of fine-grained unconsolidated deposits, northwestern Indiana and the Lake Calumet area of northeastern Illinois.

Calumet Sag

Channel

Little

Little

Calumet

Calumet

River

River

Wolf 

Lake

Lake Michigan

Cook CountyLake County

ILLINOISINDIANA

Lake

George

Indiana

Harbor

Grand

20’

41 ̊40’

41 ̊35’

87 ̊ 40’ 35’ 30’

Lake

Calumet

Canal

100

75

50

0

0

0

0

25

50

25

0

75

50

50

50

75

125 75

50

100

75

125

125

50

75

100

Thornton

Quarry

Stony

Island

EXPLANATION

LINE OF EQUAL THICKNESS—

Shows thickness of silt and 

clay deposits. Dashed where 

approximate. Interval 25 feet

SILT AND CLAY ABSENT

50

Buffington

Harbor 25

50

100

Calumet 

Blue Island

River
Geology 21

Figure 7. Continued.

0 1 2 3 4 5 MILES

0 1 234 5 KILOMETERS

Illinois Indiana

Study

Area

Calumet River

Burns 

Harbor

Calumet

River

Little

Grand Calumet 

Lagoons

Lake County

Porter County

Lake Michigan

20’ 15’ 10’ 87 ̊ 05’

100

150

125

125

100

100

125

150

100

175

125

200

175

150

125

150

125

75

75

125

100

125

175

150
22 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 8. Thickness of sand deposits, northwestern Indiana and the Lake Calumet area of northeastern Illinois.

River

Grand Cook County Lake County ILLINOIS INDIANA

Wolf 

Lake

Lake Michigan

Calumet 

Harbor

Indiana

Harbor

Lake

George

87 ̊ 40’

41 ̊ 40’

41 ̊ 35’

35’ 30’ 25’

10

20

30 20

0

10

50

60

40

25

10

25

10

0

25

40

40

25

40

40

40

Stony

Island

0

Lake

Calumet

0

Calumet Sag

Channel

25

10

Little

Little

Calumet

River

Thornton

Quarry

0

10

25

Calumet

0

SAND ABSENT WITHIN 20 FEET OF LAND SURFACE

SAND INTERSPERSED WITH FILL

SAND ORIGINALLY PRESENT BUT REMOVED BY QUARRYING

LINE OF EQUAL THICKNESS—Shows thickness of sand 

deposits where the top is within 20 feet of the land 

surface. Dashed where approximate. Interval, in feet, 

is variable

25

EXPLANATION

40

0

40

0

40

Blue Island
Geology 23

Figure 8. Continued.

Lake County

River

Calumet

Calumet River

Porter County

Little

0 1 2 3 4 5 MILES

0 1 234 5 KILOMETERS

Illinois Indiana

Study

Area

Burns 

Harbor

Grand Calumet 

Lagoons

Ogden

Dunes

Lake Michigan

20’ 15’ 10’ 87 ̊ 05’

100

50

10

40

40

50

40 25

50

50

50

40

50

10

10

25 10

50

25

100

50

50

50

25

10

10

10

0

10

0

50

100

0

40

25 10

10

0

0

0

50

0

0
24 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

deposits. Equality Formation deposits are common 

in the area of the Lake-Plain deposits.

The Lemont Drift, Wadsworth Till Member, 

Carmi Member (where not underlain by sand), and 

Lake-Plain deposits constitute a continuous layer of 

fine-grained unconsolidated material overlying the 

bedrock in almost all of the study area. These finegrained deposits are absent near Stony Island, 

Thornton Quarry, and the Calumet Sag Channel 

and are over 200 ft thick near the eastern edge of 

the study area (fig. 7). The Lemont Drift and the 

Wadsworth Till Member constitute most of the finegrained material. The Carmi Member typically is 

less than 15 ft thick (Land and Lakes Co., 1988, p. 14).

The thickness of the fine-grained unconsolidated 

deposits in Illinois was measured directly from drillers’ logs. Because of the scarcity of data points in 

Indiana, the elevations of the top of the bedrock and 

the top of the fine-grained deposits, obtained from 

drillers’ logs, were digitized into the ARC/INFO2

geographic information system. A set of adjacent 

nonoverlapping triangles, referred to as a triangulated 

irregular network (TIN), was computed from the 

digital contour data. This TIN structure formed a 

digital surface interpolated from the contour lines. 

The TIN was then converted into a lattice coverage 

representing 30 by 30 meter pixels. Applying map 

algebra, the bedrock-surface lattice was subtracted 

from the surface of the fine-grained deposit lattice to 

determine the thickness of the fine-grained unconsolidated deposits. A coverage containing the contour 

lines was created directly from the resultant lattice 

coverage. This coverage was joined in ARCEDIT 

(a module of ARC/INFO) to the digitized contour 

coverage created for Illinois. Additional smoothing 

of the contours was done interactively in ARCEDIT. 

This method does not account for the thin sand deposits directly overlying the bedrock and within the finegrained deposits, resulting in a slight overestimation of 

the thickness of the fine-grained deposits in Indiana.

In those parts of the study area where the 

fine-grained deposits are within a few feet of the 

land surface, the upper part of this unit typically is 

weathered. The weathered zone is characterized by 

an extensive network of open vertical fractures, 

macropores, soil joints, and root channels (Ecology 

2Use of the brand names ARC/INFO and ARCEDIT in 

this report is for identification purposes only and does not 

constitute endorsement by the U.S. Geological Survey.

and Environment, Inc., 1990, p. 4–17). The size 

and number of the weathering features decrease 

with depth. These features are virtually absent below 

about 30 ft (Ecology and Environment, Inc., 1990, 

p. 4–17).

In most of the area east of Lake Calumet, 

the fine-grained deposits are overlain by sands of 

the Equality Formation, the Parkland Sand, or the 

glacial sluiceway. Fill deposits consisting of sand 

are present locally along the western shore of Lake 

Calumet but are too discontinuous to be mapped at 

the scale shown in figure 8. Continuous fill deposits 

consisting primarily of sand and slag are present along 

the shore of Lake Michigan in much of the study area 

(fig. 3). These continuous fill deposits are mapped 

in figure 8 as if they were composed entirely of sand. 

The thickness of the sand deposits generally increases 

from west to east, ranging from 0 ft in most of Illinois 

west of Lake Calumet to about 100 ft along Lake 

Michigan east of the Grand Calumet Lagoons (fig. 8). 

In the extreme eastern part of the study area, two sand 

lenses are separated by a silty-clay layer.

The map of sand thickness (fig. 8) was prepared 

in the same way as the map of the thickness of finegrained unconsolidated deposits. The thickness of 

the sand deposits in Illinois was measured directly 

from drillers’ logs. Because of the scarcity of data 

points and the large changes in surface topography at 

the dunes in Indiana, digital line graph hypsography 

data were used to create a TIN representing land 

surface. The TIN surface was then converted into a 

lattice coverage. The procedure for determining 

the sand thickness was the same as that used to determine the thickness of the fine-grained unconsolidated 

deposits. The lattice representing the surface of the 

fine-grained unconsolidated deposits was subtracted 

from the land-surface lattice. The contour coverage 

was created directly from the resultant lattice coverage 

and joined to the digitized contour coverage of the 

sand thickness for Illinois. Additional smoothing 

of the contours was done interactively in ARCEDIT.

Values of sand thickness presented in figure 8 do 

not account for the presence of fill interspersed 

with the sand along Lake Michigan, resulting in an 

overestimation of the actual thickness of the sand 

in these areas.

The surficial and bedrock deposits have been 

extensively altered by human activities in this area. 

Substantial volumes of material have been removed 

during quarrying, tunneling, and excavating for 
Hydrology 25

buildings and landfills (fig. 7). The surficial geology 

also has been modified by the deposition of large 

amounts of fill including sand, silt, slag, dredging 

spoil, and municipal wastes (fig. 3). These activities 

have combined to disrupt the spatial continuity and 

homogeneity of the deposits and to modify the surface 

topography.

Hydrology

The four hydrologic units of concern to this 

study are surface-water bodies, the unconsolidated 

sand aquifer, the unconsolidated silt and clay confining unit, and the carbonate aquifer. These are the 

units most affected by industrial and waste-disposal 

activities.

Surface Water

Lake Michigan, the second largest of the 

Great Lakes, is the dominant influence on surfacewater and ground-water hydrology in the study area. 

From 1903 to 1991, the stage of Lake Michigan at 

Calumet Harbor ranged from 576.9 to 582.3 ft above 

sea level (National Oceanic and Atmospheric Administration, written commun., 1992). Water in Lake 

Michigan usually flows from east to west (Fitzpatrick 

and Bhowmik, 1990, p. 15).

Lake Calumet, at approximately 780 acres, is the 

second largest surface-water body in the study area. 

The lake occupies a depression in the postglacial topographic surface. Lake Calumet is currently divided 

into a number of basins by slag deposits (fig. 9). The 

northernmost basin is hydraulically isolated from the 

southern basins. The southern basins are interconnected by openings in the causeways separating the 

basins. Slag and other materials have been used to 

fill in wetlands surrounding Lake Calumet and to build 

several piers out into the lake.

Water is delivered to Lake Calumet by manmade drainage channels and storm sewers; no natural 

drainage is currently known to exist (Ross and others, 

1988, p. 47). The major inflow to the lake from 

surface drainage is through Pullman Creek, a drainage 

channel on the west side of the lake (fig. 9). A drainage channel at the northeastern corner of the lake and 

two storm-sewer outfalls also have been identified by 

Ross and others (1988).

Wolf Lake and Lake George, approximately 

770 and 130 acres in size, respectively, occupy 

shallow depressions between a series of sandy 

ridges. Wolf Lake is currently divided by slag 

deposits into an eastern, a central, and a western 

basin (fig. 9). Each of these basins has a different 

water level and is divided by slag deposits into a 

number of smaller, interconnected basins. Slag 

and other materials have been used to fill in parts 

of Wolf Lake, Lake George, and some of the 

surrounding wetlands.

Wolf Lake was once connected to Lake Michigan by a channel, now blocked, extending from the 

northern part of Wolf Lake. Water is currently 

delivered to Wolf Lake through manmade drainage 

channels and industrial discharge. Most of the 

discharge is from industries along the northern arm of 

the lake. The discharged water is originally pumped 

from Lake Michigan. A shallow drainage ditch on 

the western shore of Wolf Lake connects the lake to 

the Calumet River.

Lake George does not receive surface-water 

flow under most conditions. During periods of 

high water, however, Lake George may connect to 

the Indiana Harbor Canal through a series of ditches 

extending south from the lake.

In addition to the large lakes, numerous small 

lakes, ponds, and wetlands are present in this area. 

The smaller lakes generally occupy depressions on 

the lake plain or pits created by mining of sand and 

clay. Many of the smaller lakes and wetlands also 

have been modified by dredging and disposal of fill 

materials.

The Grand Calumet, Little Calumet, and 

Calumet Rivers and the Calumet Sag Channel are 

the principal rivers in the study area (fig. 9). The 

natural gradient and direction of flow in these rivers 

has been substantially altered by human activities. 

Prior to about 1810, the Little Calumet and Grand 

Calumet Rivers were two reaches of the same river, 

referred to as the Grand Konomick River (Moore, 

1959, p. 10). At that time, the Grand Konomick 

River, fed by a number of smaller streams that drained 

from the moraines to the south, meandered along the 

southern edge of the nearly flat lake plain between the 

dunes and beach ridges along the path of the Little 

Calumet River. Flowing westward from Indiana into 

Illinois, the river reversed course in a topographic 

depression between the Toleston Beach Ridge and the 

moraine at Blue Island, which was presumably formed 
26 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 9. Typical directions of surface-water flow, northwestern Indiana and the Lake Calumet area of northeastern Illinois. 

(Modified from U.S. Department of Health, Education, and Welfare, 1965, fig. V-1.)

Calumet Sag

Channel

Little

Little

Calumet

Calumet

River

River

Wolf 

Lake

Lake Michigan

Calumet 

Harbor

Indiana

Harbor

Cook CountyLake County

ILLINOISINDIANA

Lake

George

Indiana

Harbor

Grand

87 ̊ 40’

41 ̊ 40’

41 ̊ 35’

35’ 30’ 25’

Lake

Calumet

Canal

Basin 3

Basin 2

Basin 1

Western

basin

O’Brien Lock

and Dam

Storm

sewer

outfalls

Central

basin

Hart Ditch

Drainage

channel

EXPLANATION

SURFACE-WATER DIVIDE

DIRECTION OF SURFACE-WATER FLOW UNDER

TYPICAL HYDROLOGIC CONDITIONS

East

Chicago

Pullman Creek

Calumet

River

Eastern

basin

Hammond
Hydrology 27

Figure 9. Continued.

0 1 2 3 4 5 MILES

0 1 234 5 KILOMETERS

Calumet River

Grand Calumet 

Lagoons

Lake County

County Porter

Little

Calumet

River

Lake Michigan

Illinois Indiana

Study

Area

20’ 15’ 10’ 87 ̊ 05’

Burns

Harbor

Gary
28 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

by erosion along the path of the glacial sluiceway. 

Flowing eastward into Indiana, the river followed the 

approximate path of the Grand Calumet River and 

discharged into Lake Michigan near what are now the 

Grand Calumet Lagoons (Cook and Jackson, 1978, 

p. 24) (fig. 9). Sometime between about 1809 and 

1820, a small channel opened between the elbow in the 

Calumet River south of Lake Calumet and the Grand 

Konomick River. This created two rivers: 

the Little Calumet River, which flowed west from 

Indiana and discharged to Lake Michigan through the 

Calumet River; and the Grand Calumet River, which 

continued to flow to the east and discharge to Lake 

Michigan near the Grand Calumet Lagoons (Moore, 

1959, p. 10). The diversion of water from the Grand 

Calumet River reduced its current enough that at some 

time between 1840 and 1845, beach and dune deposits 

had blocked the mouth of this channel, preventing 

flow into Lake Michigan (Moore, 1959, p. 11). 

Under these conditions, the Grand Calumet and Little 

Calumet Rivers both originated in Indiana and flowed 

westward into Illinois meeting the newly extended 

Calumet River and discharging into Lake Michigan.

The Indiana Harbor Canal was constructed 

from 1901 to 1906 to connect the Grand Calumet 

River to Lake Michigan at East Chicago. This 

canal provided an additional outlet for flow to Lake 

Michigan and created a surface-water divide on the 

Grand Calumet River at the Hammond Treatment 

Plant near the East Chicago–Hammond boundary 

(U.S. Department of Health, Education and Welfare, 

1965, p. 57; G.S. Roadcap, Illinois State Water Survey, 

oral commun., 1994) (fig. 9). Under typical flow 

conditions, water in the Grand Calumet River between 

the divide and the Indiana Harbor Canal flows east 

to the canal. At the canal, this water mixes with 

water from the eastern part of the study area and 

discharges into Lake Michigan. West of the divide, 

flow is toward the Calumet River.

The Calumet Sag Channel was opened in 1922 

to connect the Calumet River system with the Illinois 

River system (Moore, 1959, p. 13). This diverted 

flow in the Calumet River from Lake Michigan to the 

Calumet Sag Channel under most flow conditions.

The reversal of flow of the Calumet River also resulted 

in a diversion of flow in the Little Calumet River and 

the western part of the Grand Calumet River to the 

Calumet Sag Channel (fig. 9).

Burns Harbor was constructed from 1924 to 

1926 (Cook and Jackson, 1978, p. 63). This project 

included dredging a portion of the Little Calumet 

River to connect the eastern part of the river to Lake 

Michigan. This construction created a surface-water 

divide on the Little Calumet River caused by high 

points in the riverbed west of Gary and east of Hart 

Ditch (U.S. Department of Health, Education and 

Welfare, 1965, p. 57) (fig. 9). Under normal flow 

conditions, flow in the Little Calumet River east of 

this divide is toward Burns Harbor and Lake Michigan, whereas flow west of this divide is toward the 

Calumet Sag Channel.

The O’Brien Lock and Dam was constructed in 

1968 to control flow between Lake Michigan and the 

Calumet Sag Channel. The O’Brien Lock and Dam 

is kept closed except during floods or to transmit barge 

traffic. Under typical conditions, the Calumet River 

flows from Lake Michigan toward the Calumet Sag 

Channel when the lock is open (fig. 9). Flow in the 

Calumet River north of the lock and dam is usually 

toward Lake Michigan when the lock is closed. 

Flow in the Calumet River south of the lock and dam 

is usually toward the Calumet Sag Channel when the 

lock is closed.

The previous discussion describes drainage 

patterns and flow directions during typical conditions. 

The locations of the flow divides on the Calumet River 

system can vary over several miles, and the directions 

of surface-water flow can be reversed depending on 

the stage of Lake Michigan—whether the O’Brien 

Lock and Dam is open or closed; the intensity, duration, and location of rainfall; and the location and 

volume of discharges to the streams (Fitzpatrick and 

Bhowmik, 1990, p. 13).

A decline in the stage of Lake Michigan by as 

little as 0.5 ft can produce a hydraulic gradient capable 

of shifting the location of the surface-water divides 

on the Little Calumet and Grand Calumet Rivers to 

the west and reversing flow in the Calumet River 

(U.S. Department of Health, Education and Welfare, 

1965, p. 60). Conversely, a rise in lake level could 

increase the amount of flow from Lake Michigan into 

the Calumet River and shift the surface-water divides 

on the Grand Calumet and Little Calumet Rivers to the 

east. Local variations in the level of Lake Michigan 

of 0.5 to 1.0 ft can be caused by wind or barometricpressure effects.

Because the Calumet Sag Channel is unable 

to transmit high volumes of flow, relatively large 

hydraulic heads can form in that part of the Calumet 

River system flowing toward the Illinois River during 
Hydrology 29

heavy rains. This may result in a westward shift 

in the surface-water divides on the Little Calumet 

and Grand Calumet Rivers. In extreme cases, the 

O’Brien Lock and Dam will be opened and water west 

of the divides will flow toward the Calumet River and 

Lake Michigan. Flow reversals on the Calumet 

River caused by opening of the O’Brien Lock and 

Dam are infrequent events that take place for short 

periods of time (U.S. Department of Health, Education 

and Welfare, 1965, p. 60–63; Fitzpatrick and 

Bhowmik, 1990, p. 14).

Ground Water

The aquifers of interest in this study are the 

surficial sand aquifer, hereafter referred to as the 

Calumet aquifer, and the carbonate aquifer, hereafter 

referred to as the Silurian-Devonian aquifer. The 

aquifers are separated by a confining unit composed 

primarily of till.

Calumet Aquifer

The surficial sands of the Dolton Member of 

the Equality Formation, the Parkland Sand, and the 

glacial sluiceway, as well as the permeable fill 

deposits constitute the Calumet aquifer (Hartke and 

others, 1975, p. 25). Thin layers of peat, muck, 

and organic-rich clay may be present in the Calumet 

aquifer, functioning as localized semiconfining units. 

These semiconfining units have minimal effect on 

overall flow in the aquifer.

The Calumet aquifer is under unconfined 

conditions and is continuous through most of the 

area east of Lake Calumet but is present only in 

scattered locations west of Lake Calumet (fig. 8). 

The saturated thickness of the Calumet aquifer 

ranges from 0 to about 70 ft and generally thickens 

to the east. Though not extensively pumped, records 

indicate that several wells drilled for commercial, 

industrial, irrigation, and drinking-water uses are 

open to the Calumet aquifer. It is unknown how 

many of these wells are currently in use.

The Calumet aquifer is recharged by direct 

infiltration from precipitation and is the primary 

pathway for lateral ground-water flow in the 

unconsolidated deposits (Watson and others, 1989, 

p. 30–31; Cravens and Zahn, 1990, p. 29–30). 

Ground water in the Calumet aquifer generally 

flows from topographic highs toward topographic 

lows. Localized changes in this pattern are a result of 

vertical barriers to ground-water flow; ground-water 

recharge from landfill leachate and ponded water; and 

ground-water discharge to sewer lines, small ditches, 

and pumping centers at quarries, underpasses, and 

sites of ground-water remediation.

Discharge from the Calumet aquifer is primarily 

to area rivers, lakes, and wetlands. Evapotranspiration also constitutes a major portion of the total 

discharge during spring and summer months 

(Rosenshein and Hunn, 1968, p. 30). Some water 

flows from the Calumet aquifer into the underlying 

confining unit.

The position of the water table in the Calumet 

aquifer ranges from near land surface along the Lake 

Michigan shoreline to more than 100 ft beneath the 

highest dunes. The depth to water in most of the 

study area is less than 15 ft (appendix 1). Lowering 

of the water table in parts of the Calumet aquifer as 

a result of ditching and draining the wetlands may 

have decreased the rate of recharge by dewatering 

the upper part of the aquifer (Rosenshein and Hunn, 

1968, p. 30). Urbanization also alters recharge by 

covering large areas with buildings and pavement, and 

by construction of storm sewers to drain excess water.

The Calumet aquifer is in good hydraulic 

connection with the surface-water bodies, except 

in the areas where sheet piles have been installed for 

bank stability. Water levels in most of the Calumet 

aquifer near the surface-water bodies rise and fall 

within moments of changes in river or lake stage 

(Lee Watson, U.S. Geological Survey, oral commun., 

1992).

Slug tests were performed in 26 wells open to 

the Calumet aquifer during this study to determine 

the horizontal hydraulic conductivity of the aquifer, 

which is necessary to estimate ground-water velocity 

(table 1). Slug testing also was used to determine 

the spatial trends in horizontal hydraulic conductivity. 

Slug tests consisted of inserting a solid cylinder below 

the water surface in the well, then measuring the 

water-level decline over time using a pressure transducer (falling-head test), followed by removing the 

cylinder from the well and measuring the water-level 

rise over time (rising-head test). Results of the 

rising-head tests and the falling-head tests were 

similar.

Slug-test data were analyzed using the technique of Bouwer and Rice (1976). This technique 

was developed for use in aquifers under unconfined 
30 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

conditions with wells that fully or partially penetrate 

the aquifer and assumes the following conditions:

1. The water-level change in the vicinity of 

the well is negligible.

2. Flow above the water table can be ignored; flow 

is only through the saturated zones.

3. Head losses as the water enters the well are 

negligible.

4. The hydraulic unit is homogeneous and 

isotropic.

These conditions are met or approximated in each of 

the hydraulic units tested.

When analyzing the slug-test data, it was 

assumed that

1. the radius of the casing is equal to the radius of the 

inner casing if the water-level altitude measured 

before the start of the test was above the top of the 

screened interval of the well. If this was not the 

case, the radius of the casing was computed 

applying the technique described by Bouwer and 

Rice (1976, p. 424);

2. the value of the length of the well through which 

water enters the aquifer is equal to the length of 

the screened interval of the well if the water-level 

altitude measured before the start of the test was 

above the top of the well screen. If this was not 

the case, the value is equal to the distance from 

the bottom of the well screen to the water level 

measured before the start of the test; and

3. the borehole radius is equal to the nominal outside 

diameter of the auger or drill bit used to drill the 

well.

These assumptions greatly simplify the analysis of 

the slug-test data and should not result in a significant 

error in the calculated horizontal hydraulic conductivities.

Although most of the slug tests resulted in 

clearly defined trends in water level with time that 

were easily analyzed (fig. 10), slug-test data from 

some of the wells did not show a linear decline in 

water level with time, complicating the data analysis. 

Where possible, these anomalous data were analyzed 

in accordance with the recommendations of Bouwer 

(1989) to obtain the value most representative of the 

horizontal hydraulic conductivity of the hydraulic unit 

tested.

The horizontal hydraulic conductivity calculated 

from slug tests in the Calumet aquifer for this study 

(table 1) and studies done by other investigators 

ranged from 6.5×10−1

 to 3.6×102 ft/d. Most values 

Table 1. Horizontal hydraulic conductivities 

calculated from slug-test data, northwestern Indiana 

and the Lake Calumet area of northeastern Illinois

[WTCA, water table in the Calumet aquifer; BCA, base of the Calumet 

aquifer; WTCU, water table in the confining unit; MCU, middle of the 

confining unit; SD, Silurian-Devonian aquifer. Well locations noted in 

appendix 1]

Horizontal

hydraulic

Well conductivity Hydrologic

number (feet per day) unit

S52 8.3Š×101 WTCA

S54 4.2Š×100 WTCA

S57 3.4Š×100 WTCA

S60 4.3Š×100 WTCA

S61 2.1Š×100 WTCA

S63 1.3Š×101 WTCA

S66 3.6Š×102 WTCA

S69 1.0Š×101 WTCA

S70 2.8Š×101 WTCA

S71 1.1Š×101 WTCA

S72 1.2Š×101 WTCA

S73 9.8Š×101 WTCA

S74 4.5Š×101 WTCA

S75 5.9Š×100 WTCA

S76 8.9Š×100 WTCA

S77 8.6Š×100 WTCA

S260 3.0Š×101 WTCA

S264 1.2Š×101 WTCA

S272 2.4Š×101 WTCA

S273 2.1Š×101 WTCA

S284 2.0Š×101 WTCA

S290 2.2Š×101 WTCA

S293 1.7Š×101 WTCA

S259 6.2Š×100 BCA

S285 2.2Š×101 BCA

S292 4.8Š×100 BCA

S49 5.4Š×10−2 WTCU

S64 1.5Š×10−2 WTCU

S50 1.4Š×10−3 MCU

S55 4.2Š×10−3 MCU

S58 5.6Š×10−3 MCU

S67 8.7Š×10−4 MCU

S53 2.0Š×10−1 SD

S59 1.5Š×10−1 SD

S62 3.3Š×10−2 SD

S65 4.4Š×10−1 SD

S68 6.2Š×10−2 SD
Figure 10. Water-level change as a function of time during slug testing, well S65, rising-head phase.

Ground Water 31

WATER-LEVEL CHANGE (y), IN FEET

0.01

10

0.1

1

0 7 23 5 1 4 6

Field data

Straight-line

fit to field data

TIME (t), IN MINUTES

r = 0.083 ftr = 0.17 ftL = 10.0 ftt = 6.94 x 10 daysy = 2.10 fty = 1.60 ftH = 59.0 ftD = 232 ftA = 3.5B = 0.30 

cw

o

t

-4

EXPLANATION

EXPLANATION OF SYMBOLS

c

w

KrrLtyyRHDAB

o

t

e

= Horizontal hydraulic conductivity, in feet per day (ft/d)= Effective radius of the well casing, in feet (ft)= Effective radius of the borehole, in feet (ft)= Length of the portion of the well through which water enters, in feet (ft)= Time since beginning of test, in days (d)= Water level at start of test, in feet (ft)= Water level some time during the test, in feet (ft) = Effective radius of the aquifer, in feet (ft)= Height of the water table above the bottom of the well, in feet (ft)= Saturated thickness of the aquifer, in feet (ft)= Aquifer coefficient related to L/r (dimensionless) w= Aquifer coefficient related to L/r (dimensionless) w

K =

ln r2

c

2L

rw ln 1

t

y

o

yt

= 0.44 ft/d

Re

=

1.1

ln r

H

w

+ ln rw

r w

A

ln B D - H

r

L

w

- 1

Re

+
32 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

were between 2.1×100 and 3.0×101 ft/d (Baker/TSA, 

1984; Geosciences Research Associates, Inc., 1987 

and 1988; Warzyn Engineering, Inc., 1987; Cravens 

and Roadcap, 1991, p. 10; Kenneth Gelting, Waste 

Management of Illinois, written commun., 1993; 

G.S. Roadcap, Illinois State Water Survey, oral 

commun; 1993: Richard Leonard, U.S. Army Corps 

of Engineers, written commun., 1993).

Horizontal-hydraulic-conductivity values 

obtained during this and other studies from slug-test 

analysis are in only fair agreement with the values 

obtained by Rosenshein and Hunn (1968, p. 29) 

from specific-capacity tests throughout Lake County. 

Rosenshein and Hunn reported a range of horizontal 

hydraulic conductivity of about 8.0×100 to 

1.3×102 ft/d, and an average value of 6.0×101 ft/d. 

This value is about double the most common values 

calculated from the slug-test data collected in this 

and other studies. Differences in the values can 

be attributed to differences in the method of analysis, 

the volume of aquifer tested, and the locations where 

testing was done.

The slug-test data indicate that the horizontal 

hydraulic conductivity of the Calumet aquifer, where 

it is composed of fill deposits, is highly variable.

Horizontal-hydraulic-conductivity values calculated 

from slug tests in 30 wells open to typical fill deposits 

(including clay, sand, silt, slag, and construction 

debris) at one of the piers in Lake Calumet varied 

from 3.7×10−4 to 8.2×101 ft/d with a median value of 

5.3×10−1

 ft/d (Lisa Grassel, Waste Management of 

North America, Inc., written commun., 1992). These 

values vary over five orders of magnitude, indicating 

that the fill deposits are highly heterogeneous. This 

indicates that ground-water flow through the fill will 

not be uniform. Flow will be primarily through the 

permeable parts of the fill, which are typically coarse 

grained, fractured, and (or) poorly consolidated.

In addition to variations in the hydraulic properties of the fill, variations in the hydraulic properties of 

the entire Calumet aquifer also exist. These variations 

can be related to differences between the hydraulic 

properties of the sand and the fill and differences in the 

thickness and composition of the sand deposits. The 

largest horizontal-hydraulic-conductivity value calculated from the slug tests in the Calumet aquifer was 

3.6×102 ft/d (table 1). This value was calculated at a 

well (S66) open to the fill deposits and is about an 

order of magnitude greater than the typical value for 

the Calumet aquifer where flow is through the sand. 

Results from the pier in Lake Calumet and station 

S66 indicate that the median horizontal hydraulic 

conductivity of the fill deposits can be substantially 

less than the typical value of the sand deposits, but the 

largest conductivity values in the fill deposits exceed 

the largest values in the sand deposits.

The horizontal hydraulic conductivity of the 

Calumet aquifer generally decreases to the west 

(fig. 11). Near Lake Michigan in Illinois, conductivity values calculated at three wells open to the 

Calumet aquifer exceeded 8.0×101

 ft/d. Horizontalhydraulic-conductivity values in much of the area 

east of Lake George are greater than or equal to 

2.0×101 ft/d, whereas values north and south of this 

area are usually from 1.0×100

 to 1.4×101 ft/d. Except 

for the highly conductive area along Lake Michigan 

and small areas along the southwestern part of Wolf 

Lake and the northeastern corner of Lake Calumet, 

the horizontal hydraulic conductivity of the Calumet 

aquifer west of Lake George is less than 2.0×101

 ft/d 

and is typically less than 1.0×101 ft/d. Hydraulicconductivity values near the eastern shore, and south 

of, Lake Calumet are usually less than 1.0×100 ft/d. 

This decrease in hydraulic conductivity coincides with 

a decrease in the thickness of the Calumet aquifer 

(fig. 8). It also coincides with a decrease in the 

size of the sand grains composing the aquifer and 

an increase in the percentage of silt and clay in the 

aquifer, which was observed during drilling operations 

(Jeff Miller, Metcalf and Eddy, Inc., oral commun., 

1992).

The horizontal hydraulic conductivity of the 

Calumet aquifer decreases with depth at a site in 

northwest Gary, Ind. (Geosciences Research 

Associates, Inc., 1988, p. 4–25), and shows no 

significant change with depth at a second site in 

southwest Gary (Geosciences Research Associates, 

Inc., 1987, p. 4–26). Where the horizontal hydraulic 

conductivity decreased with depth, the percentage 

of silt and clay in the aquifer increased with depth 

(Geosciences Research Associates, Inc., 1988, 

p. 4–25), suggesting that they are related.

Confining Unit

The confining unit is composed of the Antrim 

Shale, the silt and clay tills of the Lemont Drift 

and the Wadsworth Till, the silt and clay lacustrine 

deposits of the Carmi Member of the Equality 

Formation, and the fine-grained fill deposits. The 
Hydrology 33

confining unit separates the Calumet and the SilurianDevonian aquifers in most of the study area. In the 

eastern part of the study area, a sand aquifer is present 

within the confining unit (Shedlock and others, 1994, 

p. 16).

The water table is located in the confining unit 

in most of the area west of Lake Calumet, where the 

surficial deposits are predominately fine grained.

The confining unit is more than 200 ft thick in Porter 

County and is thin or absent near Stony Island, Thornton Quarry, and in isolated areas south of Blue Island 

(fig. 7). Except for small areas northeast of Stony 

Island and south of Blue Island, the confining unit 

underlies the Calumet aquifer restricting flow between 

the Calumet aquifer and the underlying SilurianDevonian aquifer.

The confining unit is recharged by the Calumet 

aquifer and by infiltration from precipitation where 

the Calumet aquifer is absent. Discharge from the 

confining unit is primarily to the Silurian-Devonian 

aquifer and to rivers, lakes, and wetlands. Where 

the Calumet aquifer is absent, evapotranspiration 

constitutes a major part of the discharge during spring 

and summer months (Rosenshein and Hunn, 1968, 

p. 30). The depth of the water table in the confining 

unit ranges from near land surface around Lake 

Calumet to about 27 ft below land surface near some 

of the landfills (appendix 1).

Vertical and horizontal flow in the confining 

unit is increased by a network of fractures, root 

channels, macropores, and soil joints in the weathered 

part of the unit. This weathered zone is typically 

about 30 ft thick (Ecology and Environment, Inc., 

1990, p. 4–15) and appears to be restricted to areas 

where the Calumet aquifer is less than about 5 ft 

thick (Woodward-Clyde Consultants, 1984, p. V–13). 

Though fractures are present in the deeper, unweathered parts of the confining unit, their size and number 

are greatly reduced and other forms of secondary 

permeability are absent. Vertical flow through both 

the weathered and unweathered parts of the confining 

unit is considerably greater than lateral flow (Cravens 

and Zahn, 1990, p. 37–38).

Laboratory tests of soil-moisture content of the 

confining unit were performed on saturated samples 

collected from more than 50 boreholes at 10 facilities 

in Illinois. The reported soil-moisture content 

ranged from 8 to 37 percent and decreased with depth 

at almost every borehole. The moisture content of 

the upper part of the confining unit is typically about 

20 percent. The moisture content of the lower part 

of the confining unit is typically about 15 percent. 

The soil-moisture content of a saturated deposit is 

equivalent to its porosity (Freeze and Cherry, 1979, 

p. 39).

Horizontal-hydraulic-conductivity values 

were calculated from slug tests done in 42 wells 

open to the confining unit during this and previous 

investigations. These values ranged from 1.7×10−5

to 5.5×10−1 ft/d (Geosciences Research Associates, 

Inc., 1987 and 1988; Ecology and Environment, Inc., 

1990, p. 4–37; Eldridge Engineering Assoc., 1990; 

Cravens and Roadcap, 1991, p. 10; G.S. Roadcap, 

Illinois State Water Survey, oral commun., 1993; 

Richard Leonard, U.S. Army Corps of Engineers, 

written commun., 1993; Lisa Grassel, Waste 

Management of North America, Inc., written 

commun., 1993; Luci Alteiri, Land and Lakes Co., 

written commun., 1993). Slug tests were done in 

24 wells open to the weathered zone and 18 wells 

open to the unweathered zone. The median 

horizontal hydraulic conductivity of the weathered 

part of the confining unit was calculated to be 

5.8×10−2 ft/d, whereas the median value for the 

unweathered part of the confining unit was calculated to be 2.8×10−3 ft/d.

The horizontal hydraulic conductivity within 

30 ft of the water table is substantially less where 

the water table is in the confining unit than where 

the water table is in the Calumet aquifer (fig. 11). 

East of Lake Calumet, where the water table is 

primarily in the Calumet aquifer, horizontalhydraulic-conductivity values almost always 

exceed 1.0×100 ft/d. West of Lake Calumet, 

where the water table is primarily in the confining 

unit, values are usually between 1.0×10−2 and 

7.5×10−1 ft/d.

Rosenshein (1963, p. 22) estimated an average 

vertical hydraulic conductivity of 4.0×10−4 ft/d for the 

confining unit in Lake County. Permeameter tests at 

three sites near Lake Calumet and two sites in Gary 

indicate a range of vertical hydraulic conductivity 

from 3.7×10−6 to 1.6×10−3 ft/d (Geosciences Research 

Associates, Inc., 1987 and 1988; Roy F. Weston 

Consultants, 1989, p. 5–15; Kenneth Gelting, Waste 

Management of Illinois, written commun., 1993).

The confining unit does not appear to be weathered 

at these sites. Permeameter tests from these sites do 

not indicate a correlation between vertical hydraulic 

conductivity and depth or stratigraphy within the 
34 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 11. Distribution of horizontal-hydraulic-conductivity values at wells within 30 feet of the water table, northwestern Indiana and the Lake Calumet area of northeastern Illinois.

Calumet Sag

Channel

Little

Little

Calumet

River

Lake Michigan

Cook CountyLake County

ILLINOISINDIANA

Grand

87 ̊ 40’

41 ̊ 40’

41 ̊ 35’

35’ 30’ 25’

Canal

Confining

Unit

Calumet

Aquifer

Calumet

Aquifer

Approximate boundary

between Calumet Aquifer

and Confining Unit

Confining

Unit

EXPLANATION

Greater than 100.0

No values

RANGE OF HORIZONTAL-HYDRAULICCONDUCTIVITY VALUES, IN FEET PER DAY

50.0 to 99.9

0.01 to 0.09

0.1 to 0.9

1.0 to 9.9

10.0 to 19.9

20.0 to 29.9

30.0 to 49.9

Indiana

Lake

George

Wolf 

Lake

Lake

Calumet

Calumet

River

Calumet

River

Harbor
Hydrology 35

Figure 11. Continued.

0 1 2 3 4 5 MILES

0 1 234 5 KILOMETERS

Calumet River

Gary

Harbor Grand Calumet 

Lagoons

Lake County

County Porter

Little

Calumet

River

Lake Michigan

Illinois Indiana

Study

Area

20’ 15’ 10’ 87 ̊ 05’

Gary
36 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

confining unit. It is probable, however, that the 

vertical hydraulic conductivity is greatest where the 

confining unit is weathered.

Silurian-Devonian Aquifer

The dolomite and limestone of the Racine, 

Detroit River, and Traverse Formations compose 

the Silurian-Devonian aquifer. This aquifer is 

unconfined at Stony Island and Thornton Quarry. 

Northeast of Stony Island and south of Blue Island 

the confining unit is absent and the Silurian-Devonian 

aquifer is in direct hydraulic connection with the 

Calumet aquifer (fig. 7). In the rest of the study area, 

the aquifer is semiconfined. The Silurian-Devonian 

aquifer is pumped for commercial and industrial 

supply and serves as a source of drinking water in the 

study area. The aquifer is pumped more extensively 

in Illinois than in Indiana.

The Silurian-Devonian aquifer in the study 

area is recharged primarily by vertical flow through 

the confining unit. However, recharge to the 

Silurian-Devonian aquifer through the till in any 

area is less than 1 percent of the total flow through 

the aquifer beneath that area (Land and Lakes Co., 

1988, p. 27). Where the confining unit is absent, 

recharge is from the Calumet aquifer or direct 

infiltration from precipitation.

Lateral ground-water flow in the SilurianDevonian aquifer is generally toward Lake Michigan, 

though there is localized flow toward excavations in 

the bedrock and pumping centers (Cravens and Zahn, 

1990, p. 30, 34). Movement of ground water within 

the Silurian-Devonian aquifer is primarily through an 

interconnected network of joints, fissures, faults, 

bedding plane openings, and solution cavities in the 

bedrock. Very little ground water flows through the 

rock matrix. With the exception of the extensive 

network of vertical faults in Illinois, most of the 

openings in the bedrock are irregularly distributed 

both vertically and horizontally but tend to be more 

abundant near the top of the bedrock (Suter and others, 

1959, p. 9).

Discharge from the Silurian-Devonian aquifer 

is primarily to pumping, including dewatering centers 

for the Tunnel and Reservoir Plan (TARP) (Cravens 

and Zahn, 1990, p. 30–35). Some ground water may 

discharge from the Silurian-Devonian aquifer to Lake 

Michigan through the confining unit and the Calumet 

aquifer in the eastern quarter of the study area (Watson 

and others, 1989, p. 18). Rosenshein (1963) showed 

that local recharge to the Silurian-Devonian aquifer 

through the confining unit would increase as water 

levels in the aquifer were lowered by pumping.

Horizontal-hydraulic-conductivity values 

calculated from 25 slug tests in wells open to the 

upper few feet of Silurian-Devonian aquifer ranged 

from 2.0×10−2

 to 1.1×100 ft/d (Woodward-Clyde 

Consultants, 1984, p. V-18; Geosciences Research 

Associates, Inc., 1987; Ecology and Environment, 

Inc., 1990, p. 4–37; Eldridge Engineering Assoc., 

1990; Luci Alteiri, Land and Lakes Co., written 

commun., 1993). The median value was calculated 

to be 1.6×10−1

 ft/d. No trends were identified in the 

areal distribution of horizontal hydraulic conductivity 

in the Silurian-Devonian aquifer.

Median horizontal-hydraulic-conductivity 

values calculated from the slug tests are somewhat 

larger than the median value of 6.2×10−2 ft/d calculated from water-pressure tests in deep boreholes 

drilled for the TARP (Harza Engineering Co., 1972). 

This is consistent with the analysis of Hartke and 

others (1975, p. 30), who noted that horizontalhydraulic-conductivity values are generally larger in 

the upper 200 ft of the aquifer because of weathering, 

fracturing, and development of limited karst solution 

features. Differences in the method of testing and the 

volume of aquifer tested by each method also may 

account for the differences in the values.

WATER LEVELS AND DIRECTIONS OF 

FLOW

Water levels were measured in 523 wells and at 

34 surface-water stations during a synoptic water-level 

survey on June 23–25, 1992 (appendix 1). Water 

levels were not measured during this period in seven 

of the wells listed in the appendix because of equipment problems or lack of accessibility during the 

survey. All but two water levels were measured 

between 0700 hours on June 23 and 1530 hours on 

June 24. Ground-water levels were measured at 

wells open to the Calumet aquifer, the confining unit, 

and the Silurian-Devonian aquifer. Surface-water 

levels were measured from established reference 

marks on bridges and culverts and at six USGS 

streamflow-gaging stations.

Most water levels were measured with steel 

tapes. Successive measurements were made until 

at least two measurements agreed within 0.01 ft. 
Surface Water 37

Measurements were made with electric tapes if 

obstructions in the well prevented a steel-tape 

measurement or if LNAPL’s were detected in the 

well. Measurements of LNAPL thickness were 

made with an oil-water interface tape. Corrections 

were made to account for the effects of LNAPL’s on 

ground-water levels (Farr and others, 1990, p. 50).

All steel tapes and electric tapes were calibrated 

at one well open to the water table and a second well 

open to the Silurian-Devonian aquifer. All measurements agreed to within 0.03 ft. These differences are 

minor compared to the differences in the water-level 

altitudes in the wells at different sites and no corrections for tape measurements were necessary.

Inspection of ground-water levels in well S297 

(USGS observation well 413559087270301) from July 

1986 to September 1992 shows that the water-level 

altitude in well S297 ranged from 586.8 to 591.9 ft 

above sea level (Stewart and others, 1993, p. 316) and 

averaged 589.6 ft above sea level. Well S297 is open 

to the Calumet aquifer in Indiana (fig. 4). Water 

levels in well S297 averaged 588.4 ft above sea level 

during the synoptic survey, indicating that water levels 

in the Calumet aquifer at this time may be slightly 

lower than normal (fig. 12). The lower ground-water 

levels probably resulted from below normal amounts 

of recharge from precipitation in the months prior to 

the synoptic survey.

Water levels in well S297 from June 15–29, 

1992, indicate that the synoptic survey began on the 

fifth day of a period of slowly declining ground-water 

levels in the Calumet aquifer. The water level in well 

S297 declined 0.30 ft during the synoptic period.

Water levels were monitored continuously during the synoptic survey at two other wells in Indiana 

(wells S299 and S277) (figs. 4, 13) and three wells 

in Illinois (wells S64, S57, and S59) (figs. 4, 14) to 

determine the timing and magnitude of background 

water-level changes. Wells S299, S277, and S57 

are open to the Calumet aquifer. Wells S59 and S64 

are open to the Silurian-Devonian aquifer and the confining unit, respectively. Total changes in water 

levels in these wells ranged from 0.04 to 0.30 ft. 

These changes are minor compared to the differences 

in water levels in the wells at different sites, and it is 

assumed that no corrections for background fluctuations in water level were necessary.

In addition to ground-water levels, the stage 

of Lake Michigan at Calumet Harbor (fig. 15) was 

monitored by NOAA, who provided daily mean 

water-level altitudes. The total change in the stage of 

Lake Michigan at Calumet Harbor during the synoptic 

survey was 0.19 ft. This change in stage is probably 

too small to produce significant changes in surfacewater elevation or ground-water altitudes, and no 

corrections for changes in lake stage were made.

The results of the synoptic water-level survey 

depict hydrologic conditions during June 23–25, 

1992. Seasonal variations in water levels cannot 

be accounted for and the conditions during this 

survey may not be completely representative of 

conditions during periods of heavy precipitation, 

large fluctuations in the stage of Lake Michigan, or 

changes in the amount and location of pumping from 

the aquifers.

Surface Water

Surface-water-flow directions during the synoptic survey were consistent with the typical hydrologic 

conditions described during previous investigations 

(compare fig. 9 and fig. 15). The O’Brien Lock and 

Dam was closed during the synoptic period except to 

transmit barge traffic. Though 2.02 in. of rainfall 

was measured at the University of Chicago on June 18, 

1992 (National Oceanic and Atmospheric Administration, 1992b, p. 8), the effects of the rainfall on water 

levels appear to have dissipated by the start of the 

survey. The stage of Lake Michigan did not change 

significantly during the survey.

The surface-water elevation of Lake Michigan 

was measured at Gary Harbor (SW-21) and at Calumet 

Harbor (SW-1). The surface-water elevation at both 

stations was 580.1 ft above sea level (fig. 15). The 

data are inadequate to identify the flow direction in 

Lake Michigan.

Water levels were measured at two sites in the 

eastern and western basins of Wolf Lake (fig. 15).

The water-level altitude at the western shore of Wolf 

Lake was 582.1 ft above sea level; the water-level 

altitude at the eastern shore was 583.0 ft above sea 

level. This suggests the potential for flow from east 

to west between the basins of Wolf Lake.
38 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 12. Water-level trends in well S297, northwestern Indiana and the Lake Calumet area of northeastern Illinois, Oct. 1, 1991–Sept. 30, 1992.

1991 1992

OCT NOV DEC JAN FEB MAR APR MAY JUNE JULY AUG SEPT

WATER LEVEL, IN FEET ABOVE SEA LEVEL

592.0

591.5591.0

590.5590.0589.5589.0588.5588.0587.5587.0
Surface Water 39

Figure 13. Water-level trends in wells S299 and S277, northwestern 

Indiana and the Lake Calumet area of northeastern Illinois, June 18–25, 

1992.

602.0

602.5

602.1

602.2

602.3

602.4

18 19 20 21 22 23 24 25

JUNE

580.40

580.58

580.42

580.44

580.46

580.48

580.50

580.52

580.54

580.56

22 23 24 25

W A T E R L E V E L , I N F E E T A B O V E S E A L E V E L

S299

S277
40 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 14. Water-level trends in wells S57, S59, and S64, northwestern Indiana 

and the Lake Calumet area of northeastern Illinois, June 22–24, 1992.

22 23 24

W A T E R L E V E L , I N F E E T A B O V E S E A L E V E L

JUNE

581.50

581.00

581.25

560.50

560.00

560.25

588.4

588.6

588.5

S57

S59

S64
Ground Water 41

The surface-water elevation (591.8 ft above 

sea level) measured on the Little Calumet River near 

Hart Ditch at station SW-30 is substantially higher 

than at any of the nearby stations, indicating a flow 

divide near this site (fig. 15). East of the divide, the 

Little Calumet River flows toward Burns Harbor and 

Lake Michigan. West of the divide, the Little Calumet River flows toward the Calumet Sag Channel.

The Grand Calumet River flows westward 

from its source near the Grand Calumet Lagoons into 

the Indiana Harbor Canal and Lake Michigan (fig. 15). 

Though it is likely that there is some eastward flow 

between station SW-14 and the inlet to the Indiana 

Harbor Canal, the water levels indicate that westward 

flow of the Grand Calumet River continues to its 

confluence with the Little Calumet River. Flow in 

the Little Calumet River south of the O’Brien Lock 

and Dam and west of the confluence with the Grand 

Calumet River is westward to the Calumet Sag 

Channel.

Surface-water levels at the Calumet River 

indicate a high in the vicinity of station SW-3 (fig. 15). 

This high water level appears to be caused by surfacewater discharge from Wolf Lake to the Calumet River 

at the drainage ditch near station SW-3. North of 

station SW-3, flow of the Calumet River is toward 

Lake Michigan. South of station SW-3, flow is 

toward Lake Calumet.

Several surface-water-level measurements 

(stations SW-7 and SW-8 on the Little Calumet River, 

station SW-6 on the Calumet Sag Channel) indicate 

different flow directions than those shown by the 

arrows in figure 15. The apparent discrepancies are 

probably the result of measurement errors caused by 

wind blowing the steel tape during measurement or by 

water-level changes associated with wind effects, 

stream turbulence, or obstructions in the channel 

(Sauer and Meyer, 1992, p. 14 and 16).

Surface-water gradients were determined by 

dividing the change in water level between two stations by the measured distance along the stream 

between the stations. Gradients for the Grand 

Calumet and Calumet Rivers averaged 0.4 ft/mi.

Gradients for the Little Calumet River were generally 

the largest and averaged 0.7 ft/mi. Gradients for the 

Indiana Harbor Canal were small, with an average 

value of about 0.2 ft/mi. No gradient could be calculated for the Calumet Sag Channel because only one 

data point was available.

Discharge readings were made at stations 

SW-24 and SW-31 on the Little Calumet River and 

at station SW-12 on the Grand Calumet River.

During June 23–25, 1992, daily mean discharge 

of the Little Calumet River was 37 ft3/s at station 

SW-24 and 10 ft3

/s at station SW-31 (Stewart and 

others, 1993, p. 203 and 243). Daily mean discharge 

of the Grand Calumet River averaged 18 ft3/s at station 

SW-12 (Stewart and others, 1993, p. 244).

Ground Water

The configuration of the water table and the 

potentiometric surface of the top of the SilurianDevonian aquifer were plotted to define the horizontal 

direction of ground-water flow in these units and to 

identify the factors that control ground-water levels.

Water Table

The water-table configuration generally 

follows surface topography where topographic relief 

is significant (compare fig. 4 and pl. 1). In those 

parts of the study area where the surface topography is 

relatively flat (particularly between the Calumet River, 

the Grand Calumet River, Lake Michigan, and the 

Indiana Harbor Canal), the water-table configuration 

is more complex. This is consistent with the results 

of the water-table mapping done in Indiana during 

previous studies (Watson and others, 1989, p. 32–33).

Plotting the water-table configuration is complicated by the lack of ground-water-level data in some 

parts of the study area. The well coverage between 

the western shore of Lake Calumet and the eastern 

edge of the study area is sufficient to provide a 

detailed depiction of the water-table configuration at 

the scale presented on plate 1. Data points are scarce 

or absent, however, in most of the area south of the 

Little Calumet River and west of Lake Calumet. It 

is possible that the water-table configuration in these 

areas is more complex than is shown on plate 1.

A long (approximately 5 mi) north-south 

trending ground-water divide, defined as a ridge in 

the water table from which ground water moves away 

in both directions normal to the ridge line, is present 

along the topographic ridge at Blue Island (pl. 1). 

Ground-water flow west of the divide is directed south 

and west toward the Calumet Sag Channel. Flow 

east of the divide is directed south and east toward 

the Little Calumet River and Lake Calumet.
42 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 15. Direction of surface-water flow, northwestern Indiana and the Lake Calumet area of northeastern Illinois, 

June 23–25, 1992.

Calumet Sag

Channel

Little

Little

Calumet

Calumet

River

River

Wolf 

Lake

Lake Michigan

Calumet 

Harbor

Indiana

Harbor

Cook CountyLake County

ILLINOISINDIANA

Lake

George

Indiana

Harbor

Grand

87 ̊ 40’

41 ̊ 40’

41 ̊ 35’

35’ 30’ 25’

Lake

Calumet

Canal

Hart Ditch

SW-6

578.6

SW-7

578.3

SW-34

579.2

SW-33

580.0

SW-8

578.3

SW-5

579.9

SW-4

580.5

SW-3

581.3

SW-9

582.1

SW-10

583.0

SW-11

581.3

SW-15

581.2

SW-16

580.5

SW-17

585.2

SW-18

582.1

SW-30

591.8

SW-1

580.1 SW-2

581.1

SW-12

579.1

SW-13

579.7

SW-14

580.9

SW-32

583.9

EXPLANATION

DIRECTION OF SURFACE-WATER FLOW

SURFACE-WATER-LEVEL MEASUREMENT SITE 

AND DESIGNATION—Number is water-level

elevation, in feet above sea level

CONTINUOUS MONITORING SITE AND DESIGNATION—

Number is water-level altitude, in feet above sea level

SW-15

581.2

SW-31

585.5

SW-31

585.5

SW-29

589.3

O’Brien Lock

and Dam

Calumet

River
Ground Water 43

Figure 15. Continued.

SW-19

583.4

0 1 2 3 4 5 MILES

0 1 234 5 KILOMETERS

Calumet River

Grand Calumet

Lagoons

Gary

Harbor

Lake County

County Porter

Little

Calumet

River

Lake Michigan

Illinois Indiana

Study

Area

20’ 15’ 10’ 87 ̊ 05’

SW-20

583.7 SW-21

580.1

SW-22

586.2

SW-23

587.7 SW-25

579.8

SW-26

580.0

SW-24

606.4

SW-27

587.8

SW-28

587.7

Burns

Harbor
44 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

An east-west trending ground-water divide is 

present beneath the topographic high associated with 

the Toleston Beach Ridge (pl. 1). The western extent 

of the divide is at the bend in the Little Calumet River 

near the Calumet Sag Channel. The divide extends 

eastward beyond Gary Harbor and the Grand Calumet 

Lagoons to the vicinity of Burns Harbor. North of 

the divide, ground water flows northward to the Little 

Calumet River, the Grand Calumet River, or Lake 

Michigan. South of the divide, ground water flows 

toward the Little Calumet River.

A small east-west trending ground-water divide 

is present between the Grand Calumet River and Lake 

Michigan east of the Indiana Harbor Canal. North 

of the divide, ground water flows northward to Lake 

Michigan. South of the divide, ground water flows 

southward toward the Grand Calumet River.

An elongated, east-west trending ground-water 

divide was identified between Gary Harbor and the 

Grand Calumet Lagoons. Ground water flows 

radially away from this high toward Lake Michigan, 

the Grand Calumet River, Gary Harbor, and the 

western lagoon. Near the eastern lagoon, ground 

water flows northward toward Lake Michigan.

A fourth east-west trending ground-water divide 

is present in the northern edge of the study area. 

This divide is associated with the topographic high 

at Stony Island. Flow from Stony Island is toward 

Lake Calumet and Lake Michigan.

In addition to the ground-water divides, several 

ground-water mounds, defined as a raised area in the 

water table resulting from ground-water recharge, 

have been identified in the study area. The largest 

water-table mound is the north-south trending mound 

along the western shore of Lake Calumet. Groundwater flow east of the mound is toward Lake Calumet. 

Along the northwestern part of the mound, flow is 

toward the west, changing toward the east away from 

the mound. Southwest of the mound, ground water 

flows toward the Little Calumet River. The mound is 

a local feature partially caused by enhanced recharge 

to ground water from ponded water at some of the 

industrial facilities in this area. The current well 

network is inadequate to fully define the extent of 

water-table mounding in this area, but results from 

a previous investigation do not indicate enhanced 

recharge to ground water from ponds at the Calumet 

Sewage Treatment Plant (Ecology and Environment, 

Inc., 1990, p. 4–29).

A second north-south trending ground-water 

mound is present between Lake Calumet and the 

Calumet River. This mound appears to be the result 

of additional recharge to ground water from one or 

more of the landfills in this area. Flow in the vicinity 

of this mound is toward Lake Calumet or the Calumet 

River.

Several small ground-water mounds are associated with the piers in Lake Calumet. The height and 

location of the mounds at these piers is controlled by 

enhanced recharge of ponded water to ground water.

Several depressions in the water-table surface 

were identified throughout the study area. Most 

of these are between the Calumet River, the Grand 

Calumet River, Lake Michigan, and the Indiana 

Harbor Canal. Most of the depressions in this and 

other areas appear to result from ground-water drainage into sewer lines (Watson and others, 1989, p. 30) 

(compare pl. 1 and fig. 1).

Three areas display depressions in the water 

table that cannot be attributed to ground-water drainage to sewer lines. Two of these are in the bend 

of the Little Calumet River immediately west of the 

confluence with the Grand Calumet River (pl. 1).

The eastern depression is caused by drainage to, and 

pumping from, an excavation at the southern edge of 

the landfill at this site. The western depression may 

be caused by water-level measurements in monitoring 

wells where water levels had not returned to equilibrium after dedicated sampling pumps were removed. 

Water levels in these wells are not entirely representative of actual conditions. The actual water-table 

altitude at this depression is likely to be higher than 

shown on plate 1. The third area where the water 

table is depressed is northwest of the Indiana Harbor 

Canal and east of Lake George. The water-table 

configuration in this area is affected primarily by 

pumping associated with ground-water remediation 

efforts and dewatering at highway underpasses. 

Drainage to sewer lines also has some affect on the 

water-table configuration. In this area, ground water 

flows toward Lake Michigan, the Indiana Harbor 

Canal, pumping centers, and sewers.

Silurian-Devonian Aquifer

Identifying the direction of ground-water flow 

in the Silurian-Devonian aquifer is complicated by the 

lack of ground-water-level data. Most of the wells 

open to this aquifer for environmental investigations 

are in the Lake Calumet area. Only four wells open 
Surface-Water and Ground-Water Interactions 45

to the Silurian-Devonian aquifer, none of which were 

located in the eastern third of the study area, could be 

measured in Indiana. The wells drilled for environmental investigations are open only to the top few feet 

of the aquifer. The wells drilled for the TARP are 

located over a large area of Illinois but are open to the 

aquifer over tens or hundreds of feet (S135 to S152 in 

appendix 1). Because of the long open intervals, 

water levels from the TARP wells are considerably 

lower than water levels in the shallower monitoring 

wells in the same area, indicating downward flow 

within the aquifer. Only the water levels from the 

wells open to the top 20 ft of the Silurian-Devonian 

aquifer are discussed because water-level altitudes 

from the shallow and deep wells represent different 

parts of the flow system and should not be compared.

The potentiometric surface of the top of the 

Silurian-Devonian aquifer is highest at the bedrock 

high near Stony Island (fig. 16). A second waterlevel high associated with the bedrock high northnortheast of Thornton Quarry is inferred. These 

areas are separated by a depression near the confluence of the Little Calumet and Grand Calumet Rivers. 

This depression appears to be centered at a drop shaft 

open to the aquifer that was being dewatered by 

pumping. Pumping at the drop shaft ceased shortly 

after the synoptic survey. It is unclear if the potentiometric surface shown in figure 16 is representative of 

current conditions. Ground-water pumping from the 

Silurian-Devonian and underlying aquifers at industrial facilities along the Calumet River and Lake 

Calumet also may have some effect on the potentiometric surface. The depression in the potentiometric 

surface around Thornton Quarry is attributed to 

excavation and pumping at the quarry.

Surface-Water and Ground-Water Interactions

Comparison of surface-water and ground-water 

levels indicates complex interactions between surface 

water and ground water. Ground-water contours 

indicate that the general direction of ground-water 

flow, which is perpendicular to the potentiometric 

contours, is toward the major surface-water bodies 

(pl. 1). However, ground-water levels in wells 

nearest surface-water stations indicate the potential 

for surface-water recharge to ground water in parts 

of the study area.

Interpretation of the interaction between 

surface water and ground water is further complicated 

by sheet piles driven through the Calumet aquifer. 

Gary Harbor is lined with sheet piles that extend 

east from the mouth of the harbor approximately 

1.5 mi into Lake Michigan and then south to the 

shoreline. Sheet piles also are present along long 

reaches of the Calumet River, Lake Calumet, the 

Indiana Harbor Canal, and Lake Michigan. The 

sheet piles form a barrier to the flow of surface water 

and ground water, forcing water to move under the 

wall or through cracks, holes, and joints in the sheet 

piles. As a consequence of the lack of area through 

which discharge can occur, large gradients can be built 

up between ground water and surface water. Such 

gradients are evident around Gary Harbor (pl. 1). 

Although the large hydraulic gradient indicates the 

potential for substantial flow from ground water to 

surface water, the lack of a flow pathway may (or 

may not) prevent this flow.

The surface-water elevation of Lake Michigan 

measured at station SW-1 in Calumet Harbor and 

station SW-21 in Gary Harbor was 580.1 ft above sea 

level. It is assumed, therefore, that the lake level 

throughout the study area is about 580.1 ft above sea 

level. Ground-water levels in wells nearest Lake 

Michigan exceeded the lake levels except in one well 

near the State line in Indiana. This indicates the 

potential for ground-water discharge to Lake Michigan 

in virtually all of the study area. Sheet pilings along 

Lake Michigan at several of the steel-manufacturing 

facilities restrict ground-water flow to the lake.

The surface-water elevation measured at station 

SW-4 is assumed to approximate the level of Lake 

Calumet (fig. 15). This is lower than the groundwater altitude in the wells around the lake, indicating 

the potential for ground-water discharge to Lake 

Calumet. Sheet piling along the southwestern 

corner of Lake Calumet near station SW-5 indicates 

that the higher ground-water levels in this area are 

caused by a restriction of flow behind the sheet piles.

It is unclear how much ground water is discharging 

to the lake in this area.

Surface-water/ground-water interaction at 

Wolf Lake is affected by lake level, which is affected 

by industrial discharge to the lake, and ground-water 

levels, which are affected by drainage to sewer lines. 

The surface-water elevation at station SW-10 is from 

0.2 to 0.8 ft higher than the ground-water altitude in 

nearby wells (fig. 15). This indicates the potential 
46 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 16. Potentiometric surface of the Silurian-Devonian aquifer, northwestern Indiana and the Lake Calumet area of 

northeastern Illinois, June 23–25, 1992.

Calumet Sag

Channel

Little

Little

Calumet

Calumet

River

River

Wolf 

Lake

Lake Michigan

Cook CountyLake County

ILLINOISINDIANA

Lake

George

Indiana

Harbor

Grand

87 ̊ 40’

41 ̊ 40’

41 ̊ 35’

35’ 30’ 25’

Lake

Calumet

Canal

Stony

Island

Thornton 

Quarry

570

590 580

570

560

560

570

560

570

580

580

580

550530

590

550

Calumet

River

Dewatering

Center

EXPLANATION

POTENTIOMETRIC CONTOUR—Shows altitude at which 

water level would have stood in tightly cased wells. 

Dashed where approximate. Contour interval 10 feet. 

Datum is sea level

550

WELL LOCATION
Surface-Water and Ground-Water Interactions 47

Figure 16. Continued.

0 1 2 3 4 5 MILES

0 1 234 5 KILOMETERS

Calumet River

Gary

Harbor

Lake County

County Porter

Little

Calumet

River

Lake Michigan

Illinois Indiana

Study

Area

20’ 15’ 10’ 87 ̊ 05’

590

Burns

Harbor
48 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

for surface-water discharge to ground water in most 

of the eastern basin. The eastern basin is the site of 

industrial discharge, and several large sewers are near 

this area (fig. 1). The surface-water elevation in the 

western basin at station SW-9 is about 0.9 ft lower 

than the ground-water altitude in a well about 300 ft 

west of the station, about 0.5 ft higher than the groundwater altitude in a well next to the lake about 1,400 ft 

south of the station, and about 0.3 ft lower than the 

ground-water altitude in a well next to the lake along 

the southern tip of the western basin. This indicates 

the potential for ground-water discharge to surface 

water in the west-central and southeastern parts of 

Wolf Lake and surface-water recharge to ground water 

along the southwestern part of the lake. Groundwater levels exceed surface-water levels in the northwestern part of the basin (G.S. Roadcap, Illinois 

State Water Survey, written commun., 1994). No 

industrial discharge or large sewers are present near 

the western basin, but small sewers are present in the 

residential areas southwest of the lake (fig. 2).

The measured surface-water elevations on 

the Calumet River at station SW-4 were from 0.11 to 

1.0 ft higher than ground-water levels in nearby 

wells. This indicates the potential for the river to 

recharge the Calumet aquifer in this area. The 

surface-water elevation of the Calumet River at 

station SW-2 was about 0.50 ft lower than groundwater levels in nearby wells. This indicates the 

potential for discharge from ground water to surface 

water in this area. Sheet piling is present near station 

SW-2, indicating that the higher ground-water levels 

are caused by a restriction of flow behind the sheet 

piles. It is unclear how much ground water is discharging to the river near station SW-2.

Wells are present near stations SW-12, SW-13, 

SW-19, and SW-20 on the Grand Calumet River 

(fig. 15). Ground-water levels exceeded surfacewater levels at each of these stations, indicating the 

potential for ground-water discharge to the Grand 

Calumet River over its entire reach.

Ground-water levels near the Calumet Sag 

Channel at station SW-6 are lower than surfacewater levels, indicating the potential of water from 

the Calumet Sag Channel to discharge to ground 

water in this area. The low ground-water levels 

in this area appear to be caused by drainage to 

sewer lines (compare pl. 1 and fig. 1).

The surface-water elevation of the Little 

Calumet River east of station SW-8 (fig. 15) 

exceeds ground-water altitudes in the area of the 

depression in the water table near the confluence 

of the Little Calumet and the Grand Calumet Rivers 

(pl. 1). Water from the Little Calumet River has 

the potential to discharge to ground water in this 

area. No wells are located near stations SW-24 

through SW-34 on the Little Calumet River. The 

available data indicate that ground water will 

discharge to the Little Calumet River along this 

reach.

Horizontal Hydraulic Gradients and GroundWater Velocities

Horizontal hydraulic gradients at the water 

table and at the top of the Silurian-Devonian aquifer 

were calculated with water levels measured during 

the synoptic survey. Horizontal hydraulic gradients 

were calculated by dividing the change in the altitude 

of the water table or the potentiometric surface of the 

Silurian-Devonian aquifer along two points parallel 

to the direction of ground-water flow by the horizontal 

distance between those points.

The calculated horizontal hydraulic gradient 

of the water table along nine transects along lines of 

flow in Illinois ranged from 1.2×10−3

 to 4.4×10−3 ft/ft 

(fig. 17, table 2). These values do not vary substantially with location or changes in lithology.

The calculated horizontal hydraulic gradient 

along five lines of flow at the water table in Indiana 

ranged from 7.8×10−4 to 5.1×10−3 ft/ft (fig. 17, 

table 2). The transects cross the ground-water 

divides so two values were calculated for each 

transect.

The calculated horizontal hydraulic gradient of 

the potentiometric surface of the Silurian-Devonian 

aquifer along five transects in Illinois and Indiana 

ranged from 8.8×10−4 to 1.8×10−3

 ft/ft (fig. 18, 

table 3). Gradients increase toward the pumping 

center in the dolomite aquifer north of the confluence 

of the Grand Calumet and Little Calumet Rivers.

Horizontal hydraulic gradients calculated from 

water levels collected during the synoptic survey 

generally are less than those calculated during the 

site-specific investigations. This is probably because 

of the unusually small amount of precipitation in the 

months prior to the synoptic survey and the larger 
Horizontal Hydraulic Gradients and Ground-Water Velocities 49

distances over which the horizontal hydraulic gradients were calculated.

Average linear ground-water velocity (V) at the 

water table along the lines of transect was calculated 

by solving the equation

, (1)

where

K is the horizontal hydraulic conductivity, in feet 

per day; 

I is the horizontal hydraulic gradient, in foot per 

foot; and 

n is the effective porosity, in percent.

Ground-water velocities near the water table 

in the confining unit were calculated using the 

median horizontal-hydraulic-conductivity values 

obtained from the slug tests, the horizontal hydraulic 

gradient along a transect, and a representative value 

for effective porosity (table 2). Use of a mean 

horizontal hydraulic conductivity for the calculation 

V KI = ( ) × ⁄ n

of ground-water velocity will result in an estimate 

of the velocity through a typical section of the 

confining unit. Larger or smaller ground-water 

velocities are likely locally.

The effective porosity of the Calumet aquifer 

is assumed to be 30 percent (Freeze and Cherry, 1979, 

p. 37). The horizontal hydraulic conductivity of 

the aquifer is variable along the lines of transect 

(figs. 11, 17) so approximate values were used 

(table 2). Where no data were available in Indiana, 

the horizontal hydraulic conductivity was assumed 

to be 2.0×101 ft/d. Where no data were available 

in Illinois, a value of 5.0×100

 ft/d was assumed. 

Applying these values, the calculated ground-water 

velocity through the Calumet aquifer along the lines of 

transect ranges from about 1.0×10−2

 to 3.4×10−1 ft/d.

The effective porosity of the confining unit at 

the water table is about 20 percent, whereas the 

median horizontal hydraulic conductivity in the 

confining unit at the water table was calculated to be 

5.8×10−2 ft/d. Applying these values, the groundTable 2. Calculated horizontal hydraulic gradient and ground-water velocity at the water table along 

transects, northwestern Indiana and the Lake Calumet area of northeastern Illinois

Horizontal Horizontal Horizontal

Transect hydraulic hydraulic ground-water

(see gradient Porosity conductivity velocity

fig. 17) (foot per foot) (percent) (feet per day) (feet per day)

Flow line primarily through confining unit

A-A’ 3.1×10−3 20 5.8×10−2 9.0×10−4

B-B’ 3.1×10−3 20 5.8×10−2 9.0×10−4

C-C’ 3.6×10−3 20 5.8×10−2 1.0×10−3

H-H’ 1.5×10−3 20 5.8×10−2 4.4×10−4

Flow line primarily through Calumet aquifer

X-D’ 4.4×10−3 30 1.5×100 2.2×10−2

X-E’ 2.0×10−3 30 1.5×100 1.0×10−2

X-F’ 2.6×10−3 30 1.5×100 1.3×10−2

G-G’ 3.9×10−3 30 5.0×100 6.5×10−2

G-G" 3.2×10−3 30 5.0×100 5.3×10−2

I-I’ 1.2×10−3 30 5.0×100 2.0×10−2

J-J’ 1.6×10−3 30 2.0×101 1.1×10−1

J-J" 1.8×10−3 30 2.0×101 1.2×10−1

K-K’ 9.4×10−4 30 1.0×101 3.1×10−2

K-K" 1.6×10−3 30 5.0×100 2.7×10−2

L-L’ 2.7×10−3 30 2.0×101 1.8×10−1

L-L" 1.6×10−3 30 2.0×101 1.1×10−1

M-M’ 5.1×10−3 30 2.0×101 3.4×10−1

M-M" 3.0×10−3 30 2.0×101 2.0×10−1

N-N’ 7.8×10−4 30 2.0×101 5.2×10−2

N-N" 3.6×10−3 30 2.0×101 2.4×10−1
50 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 17. Location of transects where horizontal hydraulic gradients along the water table were calculated, northwestern 

Indiana and the Lake Calumet area of northeastern Illinois, June 23–25, 1992.

Calumet Sag

Channel

Little

Little

Calumet

Calumet

River

River

Wolf 

Lake

Lake Michigan

Cook CountyLake County

ILLINOISINDIANA

Lake

George

Indiana

Harbor

Grand

87 ̊ 40’

41 ̊ 40’

41 ̊ 35’

35’ 30’ 25’

Lake

Calumet

Canal

A

B

B

C

H

X

G J

J

K

I

I

EXPLANATION

TRANSECTS—

Ground-water flow is toward the prime letter 

designation. For example, flow is from

J to J’, from J to J", and from X to F’

′

K′ G′

J′

′

J J ′

X F′

Calumet

River

D′ C′

A′

H′

G′′

′′

J J ′′

K′′

F′

E′
Horizontal Hydraulic Gradients and Ground-Water Velocities 51

Figure 17. Continued.

0 1 2 3 4 5 MILES

0 1 234 5 KILOMETERS

Calumet River

Lake County

County Porter

Little

Calumet

River

Lake Michigan

N

L′′

M′′

N′′

L

L′

M

M ′

N′

Illinois Indiana

Study

Area

20’ 15’ 10’ 87 ̊ 05’
52 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 18. Location of transects where horizontal hydraulic gradients in the Silurian-Devonian aquifer were calculated, northwestern Indiana and the Lake Calumet area of northeastern Illinois, June 23–25, 1992.

Calumet Sag Calumet

Channel

Little

Little

Calumet

River

River

Wolf 

Lake

Lake Michigan

Cook CountyLake County

ILLINOIS

INDIANA

Lake

George

Indiana

Harbor

Grand

87 ̊ 40’

41 ̊ 40’

41 ̊ 35’

35’ 30’ 25’

Lake

Calumet

Thornton 

Quarry

Canal

570

590 580

570

560

560

570

560

570

580

580

580

550

530

590

550

B

C

A

A

′

Calumet

River

EXPLANATION

POTENTIOMETRIC CONTOUR—Shows altitude at which 

water level would have stood in tightly cased wells. 

Dashed where approximate. Contour interval 10 feet. 

Datum is sea level

TRANSECTS—

Ground-water flow is toward the prime letter designation

and toward "X". For example, flow is from A to A’ and

from A to X 

550

A X

A A′

X
Horizontal Hydraulic Gradients and Ground-Water Velocities 53

Figure 18. Continued.

0 1 2 3 4 5 MILES

0 1 234 5 KILOMETERS

Calumet River

Lake County

County Porter

Little

Calumet

River

Lake Michigan

Illinois Indiana

Study

Area

20’ 15’ 10’ 87 ̊ 05’

590

D
54 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

water velocity at the water table in the confining unit 

along the lines of transect ranged from 4.4×10−4 to 

1.0×10−3 ft/d (table 2).

The effective porosity of the Silurian-Devonian 

aquifer is estimated to be about 1 percent based on 

typical porosity values of dolomite deposits (Freeze 

and Cherry, 1979, p. 375). The median horizontal 

hydraulic conductivity, as determined from the 24 slug 

tests performed by the USGS and other investigators, 

is 1.6×10−1

 ft/d. Using these values, the average 

linear ground-water velocity through the upper part 

of the Silurian-Devonian aquifer along the lines of 

transect is calculated to range from 1.4×10−2

 to 

2.9×10−2

 ft/d (table 3).

Vertical Hydraulic Gradients and GroundWater Velocities

The vertical hydraulic gradient is the difference 

in the altitude of the water levels in wells in the same 

location but open to different depths divided by the 

vertical distance separating the midpoints of the saturated open interval of the wells. If the water-level 

altitude in the shallow well is higher than that in an 

adjacent deeper well, the vertical hydraulic gradient 

is downward and water has the potential for downward 

flow. If the water-level altitude in the shallow well 

is lower than in the deep well, the vertical hydraulic 

gradient is upward and water has the potential for 

upward flow. As a convention, upward gradients are 

positive and downward gradients are negative.

Vertical hydraulic gradients between four 

hydraulic horizons—the water table and the base 

of the Calumet aquifer, the water table and the 

confining unit, the confining unit and the top of the 

Silurian-Devonian aquifer, and the water table and 

the top of the Silurian-Devonian aquifer—were 

calculated to determine the vertical direction of 

ground-water flow (table 4). Because the water 

level in well S67 had not recovered from well development during the synoptic survey, the vertical 

hydraulic gradient at the S66/S67/S68 well cluster was 

calculated using water-level measurements collected 

on October 27, 1992. It is assumed that measured 

water levels in all well clusters at which vertical 

hydraulic gradients were calculated are representative 

of hydrostatic conditions.

Forty-three sites have wells open to different 

depths in the Calumet aquifer. Differences between 

water levels within well clusters ranged from 0 to 

3.9 ft (appendix 1). Vertical hydraulic gradients were 

calculated for the 30 well clusters with differences 

in water-level altitude greater than 0.02 ft. Assuming 

an uncertainty of 0.01 ft for each measurement, waterlevel differences of 0.02 ft or less are considered indicative of horizontal flow.

Of the 30 well clusters in the Calumet aquifer 

where vertical flow was identified, downward gradients were measured at 14 well clusters and upward 

gradients were measured at 16 well clusters (table 4). 

Downward gradients range from −9.7×10−4 to 

−1.3×10−1

 ft/ft and average −2.1×10−2 ft/ft. Upward 

gradients range from 1.2×10−3

 to 3.3×10−1 ft/ft and 

average 3.6×10−2 ft/ft.

No clear pattern to the direction of vertical 

hydraulic gradients in the Calumet aquifer is evident. 

Downward gradients are present along ground-water 

divides south of Burns Harbor, on the peninsula east 

of Indiana Harbor, and between the Grand Calumet 

River, the Indiana Harbor Canal, Gary Harbor, and 

Lake Michigan (compare pl. 1 and fig. 19). Upward 

gradients are present at several well clusters along the 

ground-water divide at the Toleston Beach Ridge. 

Table 3. Calculated horizontal hydraulic gradient and ground-water 

velocity in the Silurian-Devonian aquifer along transects, northwestern 

Indiana and the Lake Calumet area of northeastern Illinois

Horizontal Horizontal Horizontal

hydraulic hydraulic ground-water

Transect gradient Porosity conductivity velocity

(see fig. 18) (foot per foot) (percent) (feet per day) (feet per day)

A-A’ 1.5×10−3 1 1.6×10−1 2.4×10−2

A-X 1.8×10−3 1 1.6×10−1 2.9×10−2

B-X 1.3×10−3 1 1.6×10−1 2.1×10−2

C-X 1.3×10−3 1 1.6×10−1 2.1×10−2

D-X 8.8×10−4 1 1.6×10−1 1.4×10−2
Table 4. Calculated vertical hydraulic gradient at selected points, northwestern Indiana and the Lake Calumet 

area of northeastern Illinois

[−, Denotes that the altitude of the water level in the deep well in the well cluster is lower than in the shallow well, indicating the potential 

for downward movement; Well locations noted in appendix 1]

Vertical Hydraulic Gradients and Ground-Water Velocities 55

Calculated vertical

Well hydraulic gradient

number (foot per foot)

Water Table in Calumet Aquifer/Base of Calumet Aquifer

S259/S260 3.3×10−1

S269/S270 4.0×10−2

S275/S276 −3.0×10−3

S338/S339 −2.3×10−2

S343/S344 −4.2×10−3

S347/S348 1.9×10−3

S350/S351 1.2×10−3

S353/S354 −2.6×10−3

S356/S357 4.7×10−2

S358/S359 8.1×10−3

S361/S362 4.8×10−3

S363/S364 −4.7×10−3

S367/S368 5.0×10−3

S372/S373 −3.2×10−2

S374/S375 5.2×10−3

S376/S377 3.7×10−3

S401/S402 2.3×10−3

S431/S432 1.0×10−1

S435/S436 −6.4×10−3

S439/S440 −9.7×10−4

S447/S448 1.8×10−3

S451/S452 2.4×10−2

S454/S455 −1.9×10−2

S456/S457 −3.3×10−3

S458/S459 −6.7×10−3

S460/S461 −1.3×10−2

S463/S464 −4.0×10−2

S466/S467 −1.3×10−1

S472/S473 3.3×10−3

S490/S491 3.8×10−3

Water Table/Middle of Confining Unit

S09/S10 −1.8×10−1

S27/S28 −6.0×10−2

S49/S50 −8.0×10−2

S54/S55 −1.0×10−1

S57/S58 −1.4×10−1

1S66/S67 −4.0×10−2

S198/S199 −3.4×10−1

S201/S202 −1.2×10−1

S201/S203 5.0×10−2

S205/S206 4.9×10−1

S207/S208 −1.1×10−1

S209/S210 −9.0×10−2

S211/S212 −1.9×10−1

S213/S214 −2.4×10−1

Base of Calumet Aquifer/Middle of Confining Unit

S339/S340 −2.0×10−1

S351/S352 −1.3×10−2

S432/S433 −3.9×10−2

S436/S437 −1.5×10−1

S440/S441 1.8×10−2

Middle of Confining Unit/Top of Silurian Aquifer

S10/S11 −2.6×10−1

S28/S29 −1.4×100

S33/S34 −5.9×10−1

S36/S37 −9.0×10−1

S58/S59 −4.0×10−1

1

S67/S68 −5.6×10−1

S199/S200 1.3×10−1

S202/S204 −2.0×10−1

S203/S204 −2.8×10−1

Water Table/Silurian Aquifer

S01/S02 −1.7×10−1

S03/S04 −5.0×10−1

S06/S07 −5.7×10−1

S09/S11 −2.2×10−1

S12/S13 −3.9×10−1

S21/S22 −6.1×10−1

S23/S24 −6.6×10−1

S25/S26 −6.1×10−1

S27/S29 −6.2×10−1

S30/S31 −5.5×10−1

S52/S53 2.2×10−2

S57/S59 −3.7×10−1

S61/S62 −1.7×10−1

S64/S65 −3.6×10−1

S66/S68 −2.9×10−1

S96/S97 −4.7×10−1

S98/S99 −2.5×10−1

S100/S101 −3.6×10−1

S103/S104 −2.6×10−1

S106/S107 −2.8×10−1

S108/S109 −2.0×10−1

S116/S117 −3.0×10−1

S118/S119 −3.5×10−1

S121/S122 −3.5×10−1

S184/S185 −2.0×10−1

S186/S187 −4.3×10−1

S188/S189 −2.0×10−1

S190/S191 −3.7×10−1

S192/S193 −3.3×10−1

S198/S200 −7.7×10−2

S201/S204 −2.2×10−1

S239/S240 −3.2×10−1

S380/S381 −1.1×10−1

S383/S385 −1.8×10−1

S447/S449 −2.6×10−2

S451/S453 −1.5×10−1

1Measurement made 10/27/92.

Calculated vertical

Well hydraulic gradient

number (foot per foot)
56 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 19. Direction of vertical hydraulic gradient within the Calumet aquifer, northwestern Indiana and the Lake Calumet 

area of northeastern Illinois, June 23–25, 1992.

Calumet Sag

Channel

Little

Little

Calumet

Calumet

River

River

Wolf 

Lake

Lake Michigan

Calumet 

Harbor

Indiana

Harbor

Cook County

Lake County

ILLINOISINDIANA

Lake

George

Indiana

Harbor

Grand

87 ̊ 40’

41 ̊ 40’

41 ̊ 35’

35’ 30’ 25’

Lake

Calumet

D

U H

D D H

U U U

H

D

H H U

D H U U

H

U H

U D

U

D

D D

H

H

U

U

U

Canal

Calumet

River

U

D

D

EXPLANATION

VERTICAL HYDRAULIC GRADIENTS 

IN CALUMET AQUIFER—

U, denotes upward gradient; 

D, denotes downward gradient; 

H, denotes vertical gradient absent

U

T o l e s t o n B e a c h R i d g e
Vertical Hydraulic Gradients and Ground-Water Velocities 57

Figure 19. Continued.

0 1 2 3 4 5 MILES

0 1 234 5 KILOMETERS

Illinois Indiana

Study

Area

Calumet River

Gary

Harbor

Burns 

Harbor

Calumet

River

Little

Lake County

Porter County

Lake Michigan

20’ 15’ 10’ 87 ̊ 05’

U H D D

H D

H

U

T o l e s t o n B e a c h R i d g e
58 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Vertical gradients are absent, indicating horizontal 

flow, at several well clusters near the Grand Calumet 

River, Burns Harbor, Wolf Lake, and parts of Lake 

Michigan. Flow in the area between Lake George, 

Lake Michigan, and the Indiana Harbor Canal is 

primarily upward or horizontal. Vertical flow in the 

Calumet aquifer appears to be affected primarily by 

pumping and drainage to sewers.

Vertical hydraulic gradients were directed 

downward at 16 of the 19 well clusters where one 

well is open to either the water table or the base of 

the Calumet aquifer and a second well is open to the 

middle of the confining unit (table 4). This indicates 

the potential for flow from the water table or the base 

of the Calumet aquifer down into the confining unit in 

most of the study area. Differences in water levels 

within wells open to the water table or the base of the 

Calumet aquifer and the middle of the confining unit 

at a cluster range from 0.23 to 11.86 ft (appendix 1). 

Downward vertical hydraulic gradients average 

−1.3×10−1 ft/ft, whereas upward gradients average 

1.9×10−1 ft/ft.

Vertical hydraulic gradients between the 

confining unit and the Silurian-Devonian aquifer 

were directed downward at eight of the nine well 

clusters measured (table 4). This indicates the 

potential for ground water to flow from the confining 

unit down to the Silurian-Devonian aquifer in most 

of the area where data are present. Differences in 

water levels within well clusters open to the confining 

unit and the Silurian-Devonian aquifer ranged from 

5.98 to 29.39 ft. Downward gradients average 

−5.7×10−1

 ft/ft. The value of the one upward 

gradient was 1.3×10−1

 ft/ft.

Vertical hydraulic gradients between the water 

table and the top of the Silurian-Devonian aquifer 

were directed downward at 35 of the 36 well clusters 

measured (table 4). This indicates the potential 

for ground-water flow from the water table down to 

the Silurian-Devonian aquifer except in the area east 

of Stony Island where flow is from the SilurianDevonian aquifer to the water table. Differences 

in water levels within well clusters open to these 

units ranged from 1.52 to 37.44 ft (appendix 1).

The average of the downward gradients was 

−3.3×10−1

 ft/ft. The value of the one upward 

gradient was 2.2×10−2

 ft/ft.

The average downward vertical hydraulic 

gradient between the water table or the base of the 

Calumet aquifer and the middle of the confining unit 

is −1.3×10−1 ft/ft. This value is substantially lower 

than the average gradient between the water table 

and the Silurian-Devonian aquifer (−3.3×10−1

 ft/ft).

Both of these gradients are less than the average 

gradient between the middle of the confining unit 

and the top of the Silurian-Devonian aquifer 

(−5.7×10−1 ft/ft). These trends are independent 

of the presence or absence of the Calumet aquifer.

These trends indicate that the vertical hydraulic conductivity of the Calumet aquifer and the weathered 

part of the confining unit are both greater than that 

of the unweathered part of the confining unit.

The vertical ground-water velocity can be 

calculated by solving equation 1 if vertical hydraulic 

conductivity is substituted for horizontal hydraulic 

conductivity and vertical hydraulic gradient is substituted for horizontal hydraulic gradient. The vertical 

and horizontal hydraulic conductivity of the unweathered part of the confining unit are approximately equal 

(Keros Cartwright, Illinois State Geological Survey, 

oral commun., 1994). Where vertical fractures are 

present, as in the weathered part of the confining unit, 

vertical hydraulic conductivity typically exceeds horizontal hydraulic conductivity. It is assumed that 

the median vertical hydraulic conductivity of the 

weathered part of the confining unit is equal to the 

median horizontal-hydraulic-conductivity value of 

5.8×10−2 ft/d. The actual value is likely to be larger. 

Laboratory tests of soil-moisture content show that 

the porosity of the weathered part of the confining 

unit typically is about 20 percent. Applying the 

average of the vertical hydraulic gradients between 

the water table and the middle of the confining unit 

(−1.3×10−1 ft/ft), the vertical ground-water velocity 

through the weathered part of the confining unit is 

conservatively estimated to be 3.8×10−2 ft/d. This is 

more than 30 times greater than the horizontal groundwater velocity in the weathered part of the confining 

unit, indicating that vertical flow will greatly exceed 

horizontal flow.

In the unweathered parts of the confining unit, 

the mean vertical hydraulic conductivity is assumed 

to be 4.0×10−4

 ft/d (Rosenshein, 1963, p. 22). The 

porosity of the confining unit at depth is about 

15 percent. If the average of the downward vertical 

hydraulic gradients between the middle of the confining unit and the top of the Silurian-Devonian aquifer 

(−5.7×10−1 ft/ft) is used, the vertical ground-water 

velocity through the unweathered part of the confining 

unit is calculated to be 1.5×10−3 ft/d. Vertical flow 
Occurrence of Light-Nonaqueous-Phase Liquids on Ground Water 59

through the unweathered part of the confining unit is 

likely to exceed horizontal flow.

OCCURRENCE OF LIGHT-NONAQUEOUSPHASE LIQUIDS ON GROUND WATER

LNAPL’s were detected in several wells near the 

petrochemical facilities in Indiana, particularly north 

and east of Lake George (table 5; figs. 2 and 20).

The measured thickness of LNAPL’s in the vicinity 

of the petrochemical facilities ranged from a thin film 

to more than 10 ft. Measurements indicate that, 

although not ubiquitous, LNAPL’s are present in a 

large part of the petrochemical land-use area.

LNAPL’s were detected in wells at several gas 

stations and at a few industrial or waste-disposal facilities in Illinois and Indiana (table 5). The measured 

thickness of LNAPL’s in these wells ranged from a 

thin film to greater than 10.0 ft. No LNAPL’s were 

detected in any well that was not near a refinery, gas 

station, industrial facility, or waste-disposal facility, 

which indicates that LNAPL’s are not likely to be 

present on ground water beneath residential areas that 

are not near such facilities.

The measured thickness of LNAPL’s in a well is 

affected by the location of the oil-water interface in 

relation to the well screen. The LNAPL’s may have 

been present at some shallow wells but were not 

detected because the water level in the well was above 

the screened interval. This could result in an underestimation of the location and thickness of LNAPL’s 

in the study area. If the oil-water interface at a well 

is located within the well screen and a capillary fringe 

is present above the water table, LNAPL’s may move 

laterally into the monitoring well. The weight of the 

LNAPL’s will depress the surface of the water in the 

well below that of the actual water table (Fetter, 1993, 

p. 225). This results in an increase in the LNAPL 

thickness and a decrease in the water-level altitude in 

the well that is not representative of conditions outside 

of the well bore. It is possible that the measured 

thickness of LNAPL’s in some of the wells is greater 

than is actually present in the aquifer. It is also possiTable 5. Light-nonaqueous-phase-liquid (LNAPL) thickness, northwestern 

Indiana and the Lake Calumet area of northeastern Illinois, June 23–24, 1992

[--, measurement not taken; >, greater than; well locations noted in appendix 1]

Measured depth Measured depth LNAPL

Well Latitude/ to LNAPL to water thickness

number Longitude (feet) (feet) (feet)

S162 414138/873326 10.02 10.52 0.50

S233 413602/873330 -- 5.71 film

S234 413601/873330 -- 4.00 film

S235 413721/873452 -- 9.42 film

S236 413720/873451 -- 9.40 film

S237 414016/873640 4.39 5.36 .97

S269 414044/872908 7.48 7.75 .27

S270 414043/872908 8.97 9.06 .09

S338 414017/872918 9.65 >20.34 >10.69

S343 414015/872858 9.14 9.19 .05

S349 413953/872919 15.44 17.69 2.25

S350 413940/872818 13.07 14.75 1.68

S416 413606/872338 -- 7.95 film

S428 413816/872822 -- -- film

S478 413831/872938 -- 7.54 film

S481 413832/872937 7.57 7.58 .01

S482 413832/872936 -- 7.18 film

S486 413832/872935 7.47 7.48 .01
60 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

Figure 20. Location of wells where light-nonaqueous-phase liquids were detected, northwestern Indiana and the 

Lake Calumet area of northeastern Illinois, June 23–25, 1992.

Calumet Sag

Channel

Little

Little

Calumet

Calumet

River

River

Wolf 

Lake

Lake Michigan

Calumet 

Harbor

Indiana

Harbor

Cook CountyLake County

ILLINOIS

INDIANA

Lake

George

Indiana

Harbor

Grand

87 ̊ 40’

41 ̊ 40’

41 ̊ 35’

35’ 30’ 25’

Lake

Calumet

Canal

Calumet

River

EXPLANATION

WELL LOCATION

1

2

3

4

5

6

8 7

9

10

14 13

15 16

17 18

19

20
Occurrence of Light-Nonaqueous-Phase Liquids on Ground Water 61

Figure 20. Continued.

0 1 2 3 4 5 MILES

0 1 234 5 KILOMETERS

Calumet River

Gary

Harbor

Lake County

County Porter

Little

Calumet

River

Lake Michigan

Illinois Indiana

Study

Area

20’ 15’ 10’ 87 ̊ 05’

Burns

Harbor

1211
62 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois

ble that the actual water-table altitude near some of 

these wells is higher than was determined from the 

water-level measurement.

The extent of the LNAPL’s at the refineries 

and industrial and waste-disposal facilities has not 

been completely defined in this study, in part because 

permission to measure LNAPL’s could not be obtained 

at a number of facilities and in a number of wells 

where LNAPL’s were known or suspected to be 

present. Furthermore, no monitoring wells were 

available at a number of industrial facilities where 

LNAPL’s may be present. The extent of LNAPL’s 

in the study area determined during this survey should 

be considered as a minimum.

SUMMARY AND CONCLUSIONS

In June 1992, the U.S. Geological Survey, in 

cooperation with the U.S. Environmental Protection 

Agency, began a study of the hydrogeology and distribution of light-nonaqueous-phase liquids (LNAPL’s) 

in a heavily industrialized area of northwestern 

Indiana and northeastern Illinois. The study was 

designed to describe the geology and hydrology in 

the area, determine the direction of surface-water 

and ground-water flow, characterize the interaction 

between surface water and ground water, and to obtain 

a preliminary estimate of the location and extent of 

LNAPL’s on the water table.

The bedrock geologic deposits of concern are 

Silurian dolomites of the Niagaran Series, lower to 

middle Devonian limestones and dolomites of the 

Detroit River and Traverse Formations, and the upper 

Devonian Antrim Shale. The Silurian deposits are 

at the bedrock surface in the western half of the study 

area. The Detroit River and Traverse Formations are 

at the bedrock surface in the central part of the study 

area. The Antrim Shale is at the bedrock surface in 

the eastern edge of the study area.

The bedrock deposits are overlain by unconsolidated silt and clay tills. The tills are at the land 

surface in most of the area west of Lake Calumet. 

Sand deposits overlie the tills and are at the land 

surface in most of the area east of the Calumet River. 

Thin silt and clay lacustrine deposits overlie the tills 

or the sands and are at the land surface around Lake 

Calumet and parts of the Little Calumet River.

The four hydrologic units of concern are 

surface-water bodies, the Calumet aquifer, the 

confining unit, and the Silurian-Devonian aquifer. 

The most important surface-water bodies are Lake 

Michigan, Lake Calumet, Wolf Lake, Lake George, 

the Calumet River, the Grand Calumet River, the Little 

Calumet River, and the Calumet Sag Channel. The 

Calumet aquifer is composed primarily of sand 

deposits. The confining unit is composed primarily 

of silt and clay tills and lacustrine deposits. The 

Silurian-Devonian aquifer is composed of Silurian 

and Devonian carbonate deposits.

The Calumet aquifer is unconfined and continuous through most of the area east of Lake Calumet 

but is only present in scattered locations west of Lake 

Calumet. The horizontal hydraulic conductivity of 

the Calumet aquifer ranges from 6.5×10−1 to 

3.6×102 ft/d and generally decreases to the west.

The water table is located in the confining unit 

in much of the area west of Lake Calumet where the 

Calumet aquifer is absent. The upper part of the 

confining unit is typically weathered where the 

Calumet aquifer is thin or absent. The confining unit 

underlies the Calumet aquifer in most of the remainder 

of the study area. The horizontal hydraulic conductivity of the confining unit ranges from 1.7×10−5

 to 

5.5×10−1 ft/d. The horizontal hydraulic conductivity 

of the weathered part of the confining unit is larger 

than that of the unweathered part of the confining unit.

The Silurian-Devonian aquifer is confined 

except at Stony Island and Thornton Quarry, where the 

water table is in the dolomite, and northeast of Stony 

Island and south of Blue Island, where the confining 

unit is absent and the aquifer is in direct hydraulic 

connection with the Calumet aquifer. The horizontal 

hydraulic conductivity of the Silurian-Devonian 

aquifer ranges from 2.0×10−2 to 1.1×100

 ft/d.

Water levels were measured in 523 wells and at 

34 surface-water stations during a synoptic water-level 

survey on June 23–25, 1992. The water-table configuration on June 23–25, 1992, generally followed 

topography. Ground-water divides were along 

topographic highs at Blue Island, Stony Island, and the 

Toleston Beach Ridge. Ground-water mounds were 

present southwest of Lake Calumet, between Lake 

Calumet and the Calumet River, and between the 

Indiana Harbor Canal, the Grand Calumet River, 

Lake Michigan, and Gary Harbor. Recharge to 

ground water from landfill leachate and ponded water 

affected the location of the ground-water mounds.

Several depressions in the water-table surface 

were also identified. The depressions in most of 

these areas appear to be caused by ground-water 
References Cited 63

drainage into sewer lines and excavations and pumping from shallow wells.

The potentiometric surface of the top of the 

Silurian-Devonian aquifer shows two highs separated 

by a depression. The northern high point is associated with the bedrock high at Stony Island. The 

southern high point is associated with the bedrock 

high at Thornton Quarry. The deepest part of the 

depression in the potentiometric surface of the 

Silurian-Devonian aquifer coincides with the location 

of a drop shaft open to the aquifer, which was being 

dewatered by pumping.

Comparison of surface-water and ground-water 

levels indicates a complex interaction between surface 

water and ground water. The general direction of 

ground-water flow inferred from plots of ground-water 

contours is toward the major surface-water bodies, but 

surface water may be discharging to ground water in 

several areas.

The horizontal hydraulic gradient at the water 

table along several transects range from 7.8×10−4 to 

5.1×10−3 ft/ft. These values do not vary substantially 

with changes in location or lithology.

The horizontal hydraulic gradient of the potentiometric surface of the Silurian-Devonian aquifer along 

several transects range from 8.8×10−4 to 1.8×10−3 ft/ft. 

These values show no significant variation with 

changes in lithology but tend to increase near the 

pumping center located near the confluence of the 

Grand Calumet and Little Calumet Rivers.

The average linear horizontal ground-water 

velocity in the Calumet aquifer ranged from 1.0×10−2

to 3.4×10−1

 ft/d. The horizontal linear ground-water 

velocity through the silt and clay deposits at the water 

table ranged from 4.4×10−4 to 1.0×10−3 ft/d. The 

ground-water velocity through the upper part of 

the Silurian-Devonian aquifer ranged from 1.4×10−2

to 2.9×10−2

 ft/d.

Vertical hydraulic gradients within the Calumet 

aquifer indicate complex vertical flow. Vertical 

hydraulic gradients indicate the potential for downward flow from the Calumet aquifer to the confining 

unit and from the confining unit to the SilurianDevonian aquifer over most of the study area.

The vertical ground-water velocity through the 

weathered part of the confining unit is calculated to 

be 3.8×10−2

 ft/d. The vertical ground-water velocity 

through the unweathered part of the confining unit is 

calculated to be 1.5×10−3 ft/d.

Light-nonaqueous-phase liquids were detected 

in several wells near the petrochemical facilities in 

Indiana and at several gas stations and a few industrial 

or waste-disposal facilities in Illinois and Indiana.

No LNAPL’s were detected in any well that was not 

near a refinery, gas station, industrial facility, or 

waste-disposal facility.

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66 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois
APPENDIX
APPENDIX 1. SUMMARY OF INFORMATION AND DATA COLLECTED DURING THE SYNOPT

OF WELLS AND SURFACE-WATER STATIONS IN NORTHWESTERN INDIANA AND THE LAKE AREA OF NORTHEASTERN ILLINOIS, JUNE 23–25, 1992[USGS, U.S. Geological Survey; ID, identification; e, estimated; *, denotes water-level altitude corrected for light-nonaqueous-phase liquid displacGeologic unit: D, Dolomite; M, Manmade land; UC, Unconsolidated deposit, coarse grained; UF, Unconsolidated deposit, fine grainedHydrologic unit: BCA, Base of Calumet aquifer; BCU, Bottom of confining unit; CA, Calumet aquifer; CSA, Confined sand aquifer; CU, Confin

Calumet aquifer; MCU, Middle of confining unit; SD, Silurian-Devonian aquifer; TCU, Top of confining unit; WTCA, Water taWRCU, Water table, confining unit; WTSD, Water table, Silurian-Devonian aquifer

Water-level altitude: NT, Measurement not takenOrganic vapor reading: B, Background value; NT, Measurement not taken

68 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois Land- Measuring 

surface point Screen altitude altitude interval 

(feet (feet (feet 

above above below 

Well Well Latitude/ USGS Site sea sea land Geologic Hydr

number name Longitude ID number level) level) surface) unit u

S01 G14S 413727/873424 413927087342401 588 590.20 18- 19 UC WTS02 A14D 413927/873424 413927087342402 588 591.09 94-104 D SS03 G204 413832/873430 413832087343001 593 594.08 13- 17 UC WTS04 A03D 413832/873429 413832087342901 592 596.51 80- 90 D SS05 G10S 413451/872934 413451087293401 587 589.94 3- 8 UC WTS06 G12S 413928/873511 413928087351101 585 586.03 9- 10 UC WTS07 G12DR 413928/873510 413928087351001 586 586.13 42- 52 D SS08 G13SR 413928/873434 413928087343401 588 591.53 3- 8 UC WTS09 G15S 413918/873418 413918087341801 586 587.77 18- 19 UC WTS10 G233 413918/873418 413918087341803 586 589.27 50- 60 UF MS11 G15DR 413918/873418 413918087341802 586 588.55 93- 98 D SS12 G16D 413907/873409 413907087340902 585 588.44 72- 82 D SS13 G16S 413907/873409 413907087340901 586 588.06 15- 16 UC WTS14 G32D 413845/873439 413845087343901 591 593.49 65- 75 D SS15 G39D 413856/873444 413856087344401 590 592.56 73- 83 D SS16 G44D 413825/873357 413824087335702 586 589.32 70- 80 D SS17 G44T 413825/873357 413824087335701 586 589.57 40- 45 UF MS18 G104 413838/873345 413838087334501 589 590.14 37- 40 UF MS19 G105 413838/873354 413838087335401 591 593.91 37- 40 UF MS20 G106 413838/873438 413838087343801 593 596.00 62- 72 UF B
Appendix 1 69

S21 MW201 413835/873438 413835087343801 588 589.62 7- 11 UC WTS22 MW202 413835/873438 413835087343802 588 590.14 59- 68 D SS23 G205 413822/873405 413822087340501 592 593.50 10- 14 UC WTS24 G206 413822/873405 413822087340502 591 593.21 65- 75 D SS25 G209 413829/873439 413829087343901 587 589.40 10- 14 UC WTS26 G210 413829/873439 413829087343902 587 589.58 63- 73 D SS27 G217 413822/873421 413822087342101 584 587.45 3- 8 UC WTS28 R252 413822/873422 413822087342203 588 590.65 33- 43 UF MS29 G216 413822/873421 413822087342102 584 586.43 56- 62 D SS30 G221 413827/873418 413827087341801 586 588.53 5- 10 UC WTS31 G220 413827/873418 413827087341802 588 588.14 69- 78 D SS32 G231 413908/873453 413908087345301 589 591.69 46- 56 UF MS33 G232 413928/873435 413928087343501 591 593.75 50- 60 UF MS34 R13D 413928/873434 413928087343401 589 590.94 74- 84 D SS35 G234 413907/873435 413907087343501 588 590.10 50- 60 UF MS36 G235 413912/873456 413912087345601 590 592.64 43- 53 UF MS37 R23D 413913/873457 413913087345701 587 590.10 68- 78 D SS38 G251 413824/873411 413824087341101 587 588.80 35- 45 UF MS39 P4E 413856/873425 413856087342501 595 598.13 17- 22 UC WTS40 P6W 413909/873435 413909087343501 588 591.35 10- 15 UC WTS41 P7W 413900/873443 413900087344301 590 592.45 5- 10 UC WTS42 R251 413824/873411 413824087341101 584 588.80 35- 45 UF MS43 1 413915/874151 413915087415101 596 597.55 14- 24 UC WTS44 2 413918/874237 413918087423701 596 597.30 8- 18 UC WTS45 3 413922/874322 413922087432201 593 595.01 19- 29 UC WTS46 SE 413841/873555 413841087355501 591 594.46 30- 40 UF WTS47 NE 413852/873554 413852087355401 593 594.25 30- 40 UF WTS48 NW 413434/873032 413434087303201 596 599.43 30- 40 UF WTS49 BH1S 414238/874011 414238087401101 667 667.25 5- 15 UF WTS50 BH1D 414238/874011 414238087401102 665 665.47 75- 90 UF MS51 BH2 414140/874219 414140087421901 626 626.13 10- 20 UF WTS52 BH4S 414442/873257 414442087325701 585 586.26 8- 13 UC WTS53 BH4D 414442/873257 414442087325702 587 586.97 23- 33 D SS54 BH5S 413919/873230 413919087323001 584 583.98 10- 15 UC WTS55 BH5D 413919/873230 413919087323002 584 583.54 45- 55 UF M

Land- Measuring 

surface point Screen altitude altitude interval 

(feet (feet (feet 

above above below 

Well Well Latitude/ USGS Site sea sea land Geologic Hydr

number name Longitude ID number level) level) surface) unit u
70 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois S56 BH6 414340/873432 414340087343201 602 603.15 11- 21 D WT

S57 BH7S 413910/873358 413910087335801 588 586.90 7- 17 UC WTS58 BH7I 413910/873358 413910087335802 588 587.05 19- 29 UF MS59 BH7D 413910/873358 413910087335803 588 587.06 69- 79 D SS60 BH8 413932/873131 413932087313101 584 586.85 15- 30 UC WTS61 BH9S 413929/873158 413929087315801 584 587.84 13- 23 UC WTS62 BH9D 413929/873158 413929087315802 585 587.63 83- 93 D SS63 BH11 413952/873259 413952087325901 585 585.16 18- 28 UC WTS64 BH16S 414250/873624 414250087362401 596 599.11 28- 38 UF WTS65 BH16D 414250/873624 414250087362402 596 599.72 68- 78 D SS66 BH18S 414315/873131 414315087313101 591 594.13 8- 18 M WTS67 BH18I 414316/873131 414316087313102 592 594.35 35- 45 UF MS68 BH18D 414316/873131 414316087313103 592 595.35 58- 68 D SS69 BH21 413832/873236 413832087323601 586 588.20 3- 13 UC WTS70 BH22 413948/873218 413948087321801 586 588.82 13- 23 UC WTS71 BH23 414038/873805 414038087380501 624 624.37 8- 18 UC WTS72 BH24 414113/873222 414113087322201 587 589.33 6- 16 UC WTS73 BH25 414151/873202 414151087320201 586 590.10 6- 16 UC WTS74 BH28 414156/873317 414156087331701 585 Unknown 7- 17 UC WTS75 BH31 413947/873025 413947087302501 600 Unknown 18- 28 UC WTS76 BH32 414141/873437 414141087343701 586 Unknown 8- 18 UC WTS77 BH33 414034/873147 414034087314701 587 Unknown 13- 23 UC WTS78 IC 413511/873003 413511087300302 590 590.00 53- 58 D SS79 IT 414217/873350 414217087335001 585 585.00 79- 84 D SS80 IP 414132/873659 414132087365901 591 591.00 72- 77 D SS81 I1 413938/873507 413938087350701 586 585.90 7- 11 UF WTS82 I2 413944/873525 413944087352501 587 587.63 5- 15 UF WTS83 I3 413958/873536 413958087353601 584 584.49 3- 13 UF WTS84 I6 414016/873542 414016087354201 584 584.68 3- 8 UF WTS85 I8 414037/873604 414037087360401 583 583.67 9- 14 UF WTS86 I9 414104/873604 414104087360401 585 585.60 6- 11 UF WTS87 I10 414037/873607 414037087360701 585 585.41 5- 10 UF WTS88 I12 414138/873548 414138087354801 585 585.13 5- 10 UF WTS89 I13 414210/873525 414210087352501 587 587.21 4- 14 UF WTS90 I14 413950/873430 413950087343001 589 589.14 10- 15 UC WT

Land- Measuring 

surface point Screen altitude altitude interval 

(feet (feet (feet 

above above below 

Well Well Latitude/ USGS Site sea sea land Geologic Hydr

number name Longitude ID number level) level) surface) unit u
Appendix 1 71

S91 I15 414011/873430 414011087343001 589 589.38 10- 15 UC WTS92 I16 414023/873430 414023087343001 587 587.46 9- 14 UC WTS93 I20 414025/873323 414025087334301 591 590.09 10- 15 UC WTS94 I21 413932/873338 413932087333801 590 589.89 7- 12 UC WTS95 11S 413855/873536 413855087353601 597 599.52 20- 25 UF WTS96 12S 413848/873520 413848087352001 585 587.06 21- 26 UC WTS97 12D 413848/873520 413848087352002 585 587.01 50- 55 D SS98 17S 413852/873550 413852087355001 597 600.60 21- 26 UF WTS99 17D 413852/873550 413852087355002 597 599.82 50- 55 D SS100 18S 413853/873526 413853087352601 601 603.69 23- 28 UF WTS101 18D 413853/873526 413853087352602 601 604.09 57- 62 D SS102 14S 413839/873528 413839087352801 588 590.90 25- 30 UF WTS103 15S 413828/873551 413828087355101 592 594.10 25- 30 UF WTS104 15D 413828/873551 413828087355102 590 594.30 47- 57 D SS105 16S 414050/873430 414050087343001 591 593.10 14- 19 UF WTS106 19S 413840/873539 413840087353901 588 591.30 13- 18 UF WTS107 19D 413840/873539 413840087353902 588 591.20 53- 58 D SS108 101S 413839/873551 413839087355101 588 593.40 14- 19 UF WTS109 105S 413828/873529 413828087352901 585 588.70 8- 15 UF WTS110 105D 413828/873529 413828087352902 585 589.60 53- 58 D SS111 W4 414103/873608 414103087360801 586 588.79 1- 10 UF WTS112 W5 414058/873608 414058087360801 588 589.71 2- 12 UF WTS113 W6 414050/873608 414050087360801 587 589.48 4- 15 UF WTS114 1A 414057/873634 414057087363401 592 594.38 5- 15 UF WTS115 7 414044/873608 414044087360801 589 591.38 5- 15 UF WTS116 G11S 413510/873259 413510087325001 598 601.38 8- 16 UF WTS117 G11D 413510/873259 413510087325002 600 602.94 94- 96 D SS118 G13S 413511/873321 413511087332101 598 601.10 9- 19 UF WTS119 G13D 413511/873321 413511087332102 598 601.10 84- 87 D SS120 G15S 413510/873309 413510087330901 600 603.98 18- 23 UF WTS121 G16S 413458/873300 413458087330001 600 603.35 17- 22 UF WTS122 G16D 413458/873300 413458087330002 600 603.23 86- 91 D SS123 G17S 413505/873258 413505087325801 601 604.40 17- 22 UF WTS124 G18S 413501/873313 413501087331301 599 602.00 13- 18 UF WTS125 R15S 413510/873309 413501087330901 601 603.00 14- 19 UF WT

Land- Measuring 

surface point Screen altitude altitude interval 

(feet (feet (feet 

above above below 

Well Well Latitude/ USGS Site sea sea land Geologic Hydr

number name Longitude ID number level) level) surface) unit u
72 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois S126 MW1 414301/873138 414301087313801 595 597.04 11- 21 M WT

S127 MW3 414302/873136 414302087313601 596 597.98 13- 23 M WTS128 MW4 414302/873136 414302087313601 594 596.06 11- 21 M WTS129 MW5 414303/873135 414303087313501 594 595.85 10- 20 M WTS130 MW6 414301/873138 414301087313801 592 594.00 9- 19 M WTS131 L1 414018/873413 414018087341302 595 599.00 16- 21 UC WTS132 L2 413955/873425 413955087342502 591 595.00 11- 17 UC WTS133 L3 413950/873408 413950087340802 592 596.00 13- 18 UC WTS134 L4 414010/873353 414010087335302 592 596.00 14- 19 UC WTS135 W1 414216/873459 414216087345902 596 596.10 85-119 D SS136 W2 414144/873438 414144087343802 590 590.30 107-167 D SS137 W3 414143/873516 414143087351602 588 588.70 91-149 D SS138 W4 414208/873525 414208087352502 591 591.30 91-126 D SS139 OC1 413907/874251 413907087425102 599 599.48 57-251 D SS140 OC2 413907/874210 413907087421002 604 604.68 68-267 D SS141 OC3 413909/874046 413909087404602 594 593.98 47-266 D SS142 QC5 413633/873704 413633087370402 596 595.98 275-329 D SS143 QC7 413721/873706 413721087370602 597 600.80 283-335 D SS144 QC10 413807/873228 413807087322802 588 589.23 250-303 D SS145 QC11 413838/873259 413838087325902 584 586.68 255-308 D SS146 QC12 413839/873331 413839087333102 581 583.68 258-326 D SS147 QC13 413829/873439 413829087343902 572 574.98 267-335 D SS148 QC14 413929/873552 413929087355202 580 583.28 275-343 D SS149 QC15 413830/873635 413830087363502 605 607.70 284-352 D SS150 QC16 414253/872711 414253087271102 594 596.36 261-300 D SS151 QC17 413551/873842 413551087384202 600 603.35 262-310 D SS152 QC18 413548/873749 413548087374902 594 597.38 269-318 D SS153 WP1 413937/873219 413937087321901 584 586.95 15- 20 UC BS154 WP2 413937/873219 413937087321902 584 586.88 9- 12 UC MS155 WP3 413937/873219 413937087321903 584 587.33 2- 7 UC WTS156 WP4 413937/873221 413937087322101 584 588.04 3- 18 UC WTS157 WP5 413938/873220 413938087322001 584 587.16 15- 18 UC WTS158 MW1 414209/873322 414209087332201 587 590.03 3- 13 UC WTS159 MW2 414157/873316 414157087331601 593 595.23 10- 20 UC WTS160 MW3 414150/873330 414150087333001 590 590.78 6- 16 UC WT

Land- Measuring 

surface point Screen altitude altitude interval 

(feet (feet (feet 

above above below 

Well Well Latitude/ USGS Site sea sea land Geologic Hydr

number name Longitude ID number level) level) surface) unit u
Appendix 1 73

S161 MW4 414145/873328 414145087332801 590 592.56 9- 19 UC WTS162 MW5 414138/873326 414138087332601 591 592.95 7- 17 UC WTS163 G101A 414048/873506 414048087350601 589 591.08 10- 15 M WTS164 G110 414054/873451 414054087345101 592 593.67 10- 15 M WTS165 G120S 414054/873451 414054087345101 591 593.84 13- 18 M WTS166 G121S 414056/873450 414056087345001 592 593.89 13- 18 M WTS167 G123S 414055/873445 414055087344501 591 594.13 13- 18 M WTS168 G124S 414053/873446 414053087344601 591 593.28 13- 18 M WTS169 G305 414058/873442 414058087344201 589 591.36 4- 14 M WTS170 G307 414100/873435 414100087343501 588 590.64 4- 14 M WTS171 P322 414056/873442 414056087344201 589 591.51 3- 8 M WTS172 P323 414058/873437 414058087343701 589 591.37 8- 12 M WTS173 P329 414054/873443 414054087344301 590 592.28 15- 20 M WTS174 P334 414051/873435 414051087345501 589 592.44 6- 11 M WTS175 G342 414048/873441 414048087344101 590 592.36 10- 15 M WTS176 G343 414050/873435 414050087343501 589 591.85 5- 15 M WTS177 G348 414047/873440 414057087344001 590 592.91 6- 11 M WTS178 G349 414048/873441 414048087344101 591 593.39 6- 11 M WTS179 B17S 414105/873411 414105087341101 590 590.55 4- 14 UC WTS180 G122 414113/873403 414113087340301 586 588.99 6- 16 UC WTS181 SS1D 414121/873353 414121087335302 586 588.54 95-111 D SS182 SS2D 414117/873433 414117087343302 582 582.96 70-100 D SS183 ST3S 414142/873433 414142087343301 586 587.45 2- 12 UF WTS184 ST1S 414106/873355 414106087335501 584 586.77 2- 11 UC WTS185 ST1D 414106/873355 414106087335502 588 588.75 98-115 D SS186 ST2S 414139/873352 414139087335201 586 586.60 5- 15 UC WTS187 ST2D 414139/873352 414139087335202 583 586.54 39- 61 D SS188 ST4S 414104/873431 414104087343101 588 591.39 10- 15 UC WTS189 ST4D 414104/873431 414104087343102 590 590.91 80-103 D SS190 GA1S 414050/873413 414050087341301 596 598.75 14- 24 UC WTS191 GA1D 414050/873413 414050087341302 596 598.95 90-100 D SS192 GA4S 414025/873412 414025087341201 597 599.37 9- 19 UC WTS193 GA4D 414025/873412 414025087341202 596 599.28 85- 95 D SS194 G13D 414025/873430 414025087343002 589 594.54 78- 84 D SS195 G14S 414026/873430 414026087343001 589 594.45 5- 15 UC WT

Land- Measuring 

surface point Screen altitude altitude interval 

(feet (feet (feet 

above above below 

Well Well Latitude/ USGS Site sea sea land Geologic Hydr

number name Longitude ID number level) level) surface) unit u
74 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois S196 G15D 413531/873051 413531087305102 588 590.49 76- 81 D S

S197 G16S 413531/873051 413531087305101 588 590.94 6- 16 UC WTS198 G11S 414103/873431 414103087343101 589 589.80 12- 17 UC WTS199 G11D 414103/873431 414103087343101 589 590.52 50- 53 UF MS200 G11B 414103/873431 414103087343102 588 591.02 94- 99 D SS201 G13S 414103/873408 414103087340801 593 594.76 14- 20 UC WTS202 G13D 414103/873408 414103087340801 593 594.44 20- 25 UF TS203 G23D 414104/873409 414104087340401 591 592.87 39- 44 UF MS204 G13B 414103/873408 414103087340802 591 593.13 107-113 D SS205 G15S 414104/873418 414104087341801 592 593.91 15- 20 UC WTS206 G15D 414104/873418 414104087341801 593 594.86 38- 43 UC MS207 G19S 414103/873355 414103087335501 592 593.79 14- 19 UC WTS208 G19D 414103/873355 414103087335501 591 593.54 38- 48 UF MS209 G20S 414050/873351 414050087335101 589 590.53 11- 16 UC WTS210 G20D 414050/873351 414050087335101 588 590.13 35- 40 UF MS211 G21S 414044/873351 414044087335101 590 592.49 11- 16 UC WTS212 G21D 414044/873351 414044087335101 592 592.73 45- 50 UF MS213 G22S 414044/873408 414044087340801 594 595.66 16- 21 UC WTS214 G22D 414044/873408 414044087340801 595 595.70 38- 43 UF MS215 R105 414054/873431 414054087343101 592 593.15 15- 19 UF WTS216 G105B 414050/873430 414050087343002 591 593.31 92- 97 D SS217 G108 414044/873359 414044087335901 588 589.27 18- 23 UC WTS218 G130B 414049/873410 414049087341002 597 599.62 111-117 D SS219 MW1 414109/874051 414109087405101 644 644.10 2- 12 UF WTS220 MW2 414105/874050 414105087405001 644 644.27 2- 12 UF WTS221 MW5 414101/874313 414101087431301 598 598.06 2- 12 UF WTS222 MW2 414101/874313 414101087431301 599 599.68 3- 13 UF WTS223 MW8 414332/874316 414332087431601 621 620.90 5- 25 UF WTS224 MW9 414432/874316 414432087431601 621 620.91 5- 15 UF WTS225 MW103 414410/873653 414410087355301 588 588.39 Unknown Unknown UnkS226 MW101 414410/873653 414410087355301 588 587.50 Unknown Unknown UnkS227 TB 414439/873307 414439087330701 588 588.14 Unknown Unknown UnkS228 TA 414440/873306 414440087330601 589 588.64 Unknown Unknown UnkS229 MW6 414208/873133 414208087313301 589 589.13 4- 8 UC WTS230 MW10 414209/873134 414209087313401 589 588.98 4- 8 UC WT

Land- Measuring 

surface point Screen altitude altitude interval 

(feet (feet (feet 

above above below 

Well Well Latitude/ USGS Site sea sea land Geologic Hydr

number name Longitude ID number level) level) surface) unit u
Appendix 1 75

S231 MW04 413748/873330 413748087333001 585 585.41 3- 13 UC WTS232 MW13 413748/873332 413748087333201 586 585.73 2- 23 UC WTS233 MW01A 413602/873330 413602087333001 602 602.38 3- 13 UC WTS234 MW03 413601/873330 413601087333001 601 601.77 2- 12 UF WTS235 TA 413721/873452 413721087345201 606 606.10 7- 17 UC WTS236 TB 413720/873451 413720087345101 605 605.54 7- 17 UC WTS237 G102 414016/873640 414016087364001 596 597.96 3- 8 UF WTS238 G104 414015/873645 414015087364501 595 596.21 7- 12 UF WTS239 FILO9 414018/873647 414018087364701 584 587.21 15- 30 UF WTS240 FILO10 414018/873647 414018087364702 586 587.44 71- 81 D SS241 FILO12 414028/873644 414028087364401 593 595.90 5- 19 UF WTS242 A-1 413647/871919 413647087191901 604 605.46 18- 21 M WTS243 A-2 413706/871818 413706087181800 603 604.71 34- 39 UC MS244 A-3 413631/871820 413631087182000 590 590.90 3- 6 M WTS245 A-4 413630/871821 413630087182100 603 605.70 18- 23 UC MS246 A-5 413629/871921 413629087192102 601 603.34 18- 21 UC WTS247 A-6 413706/871701 413706087170101 589 589.66 4- 7 UC WTS248 A-10 413626/871919 413626087191901 590 591.39 12- 15 UC WTS249 A-15 413617/871912 413617087191201 591 592.11 2- 5 UC WTS250 A-20 413503/871935 413503087193501 614 616.15 21- 24 UC WTS251 B-1 413637/872343 413637087234301 585 585.76 9- 12 UC WTS252 B-2 413752/872235 413752087223500 608 610.61 43- 48 UC MS253 B-3 413633/872220 413633087222000 594 595.97 18- 23 UC MS254 B-5 413632/872340 413632087234001 589 590.43 7- 10 UC WTS255 B-7 413617/872252 413617087225202 596 596.71 8- 11 UC WTS256 B-8 413617/872252 413617087225201 596 598.82 32- 37 UC BS257 B-10 413544/872337 413544087233700 607 608.80 17- 20 UC WTS258 C-1 413830/872600 413830087260000 587 588.85 4- 7 UC WTS259 C-4 413828/872513 413828087251302 589 591.76 8- 13 UC WTS260 C-3 413828/872513 413828087251301 589 591.81 25- 28 UC MS261 C-5 413655/872752 413655087275202 585 586.43 2- 5 UC WTS262 C-12 413650/872620 413650087262000 584 587.36 13- 18 UC MS263 C-15 413650/872748 413650087274802 583 585.58 1- 9 UC WTS264 C-18 413607/872522 413607087252200 595 594.96 17- 22 UC BS265 C-19 413617/872620 413617087262001 592 593.29 2- 5 UC WT

Land- Measuring 

surface point Screen altitude altitude interval 

(feet (feet (feet 

above above below 

Well Well Latitude/ USGS Site sea sea land Geologic Hydr

number name Longitude ID number level) level) surface) unit u
76 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois S266 C-20 413557/872839 413557087283901 593 595.41 3- 6 UC WT

S267 C-25 413527/872543 413527087254301 599 600.33 2- 5 UC WTS268 D-1 414052/872912 414052087291201 590 591.72 8- 11 UC WTS269 D-5 414044/872908 414044087290801 588 589.99 2- 7 UC WTS270 D-10 414043/872908 414043087290802 588 591.43 7- 10 UC WTS271 D-11 414043/872908 414043087290801 588 590.79 17- 22 UC MS272 D-20 413941/872900 413941087290000 588 590.31 6- 9 UC WTS273 D-21 413941/872926 413941087292600 584 587.21 13- 18 UC MS274 D-25 413909/872803 413804087291102 588 590.56 5- 8 UC WTS275 D-30 413907/872758 413758087290702 586 587.53 6- 9 UC WTS276 D-31 413907/872758 413907087275901 586 588.72 12- 17 UC MS277 D-35 413906/872757 413757087290601 586 589.86 4- 7 UC WTS278 D-40 413835/872851 413835087245101 584 586.17 4- 7 UC WTS279 D-45 413812/872702 413812087270201 586 587.67 6- 9 UC WTS280 D-50 413800/872854 413800087285401 585 587.74 9- 12 UC WTS281 D-55 413758/872814 413758087281401 585 588.94 5- 8 UC WTS282 D-60 413758/872810 413758087281001 587 589.97 5- 8 UC WTS283 D-66 413654/872740 413654087274000 587 590.41 17- 22 UC MS284 D-67 413647/872825 413647087282502 589 589.16 4- 7 UC WTS285 D-68 413647/872825 413647087282501 589 590.82 18- 23 UC MS286 D-70 413515/872914 413515087291401 603 604.66 6- 9 UC WTS287 D-75 413435/872919 413435087291901 601 603.09 5- 8 UC WTS288 E-1 413844/873104 413844087310401 582 583.53 5- 8 UC WTS289 E-2 414105/872939 414105087293900 585 586.23 3- 6 UC WTS290 E-3 414013/873033 414013087303300 585 587.98 8- 13 UC MS291 E-5 413810/873052 413810087305201 587 588.16 9- 12 UC WTS293 E-6 413938/873043 413938087304301 586 589.40 17- 22 UC BS292 E-7 413938/873043 413938087304302 586 588.11 2- 5 UC WTS294 E-10 413722/873041 413722087304101 586 587.42 6- 9 UC WTS295 E-15 413720/873042 413720087304201 584 587.05 6- 9 UC WTS296 E-20 413627/873105 413627087310500 592 594.03 5- 8 UC WTS297 LK-13 4135590872703 413559087270301 592 595.41 18- 23 UC BS298 24 413817/870513 413817087051301 609 610.63 7- 10 UC WTS299 25 413842/870512 413842087051201 605 608.30 11- 14 UC WTS300 26 413831/870713 413831087071301 611 614.47 20- 23 UC WT

Land- Measuring 

surface point Screen altitude altitude interval 

(feet (feet (feet 

above above below 

Well Well Latitude/ USGS Site sea sea land Geologic Hydr

number name Longitude ID number level) level) surface) unit u
Appendix 1 77

S301 27 413840/870711 413840087071101 606 608.94 22- 25 UC WTS302 102 413821/870625 413821087062502 620 621.66 81- 84 UC CS303 105 413744/870635 413744087063702 609 610.37 71- 76 UC CS304 106 413744/870635 413744087063701 610 610.87 20- 25 UC MS305 225 413645/870518 413645087051500 638 637.63 47- 52 UC BS306 228 413643/870736 413637087073100 635 634.30 43- 48 UC BS307 230-24 413701/871109 413651087110503 611 611.09 24- 27 UC MS308 230-58 413701/871109 413651087110502 611 610.56 50- 55 UC BS309 230-128 413701/871109 413651087110501 611 610.72 114-119 UC CS310 232 413730/871230 413726087123600 597 596.42 38- 43 UC BS311 234-142 413547/871458 413545087145501 613 612.47 130-135 UC CS312 235-45 413628/871449 413629087142600 606 605.51 37- 42 UC BS313 237-45 413549/871638 413550087163800 608 607.88 34- 39 UC BS314 238 413705/871655 413705087165500 604 607.08 58- 63 UC BS315 242 413708/870923 413656087091500 600 603.20 75- 80 UC CS316 244-65 413738/871059 413732087105702 629 631.52 57- 62 UC BS317 244-125 413738/871059 413732087105701 629 631.38 115-120 UC CS318 D-2A 413838/870645 413838087064502 608 609.67 13- 16 UC WTS319 D-4A 413843/870628 413843087062802 605 607.92 10- 13 UC WTS320 D-5A 413836/870610 413836087061002 607 610.15 10- 13 UC WTS321 D-6A 413847/870556 413847087055602 605 606.65 10- 13 UC WTS322 G-1 413821/870709 413821087070901 626 627.41 40- 45 UC BS323 G-4 413821/870650 413821087065001 621 624.17 21- 26 UC MS324 G-4A 413821/870650 413821087065003 622 624.71 32- 35 UC MS325 MW-1 413603/871645 413603087164501 603 604.83 6- 9 UC WTS326 MW-2 413618/871646 413618087164601 601 603.25 3- 6 UC WTS327 MW-5 413632/871613 413622087161301 603 604.22 4- 7 UC WTS328 MW-10 413702/871622 413702087162201 594 594.63 6- 9 UC WTS329 W-1A 413625/871318 413625087132001 606 607.98 6- 9 UC WTS330 W-2 413602/871427 413602087142701 608 611.30 11- 14 UC WTS331 W-3Dune 413609/871427 413609087142802 606 607.70 7- 10 UC WTS332 W-3West 413609/871427 413609087142801 604 607.30 6- 9 UC WTS333 W-4 413554/871427 413554087142701 609 611.00 6- 9 UC WTS334 W-5 413605/871403 413605087140301 606 607.10 6- 9 UC WTS335 W-6 413601/871503 413601087150301 604 604.91 2- 5 UC WT

Land- Measuring 

surface point Screen altitude altitude interval 

(feet (feet (feet 

above above below 

Well Well Latitude/ USGS Site sea sea land Geologic Hydr

number name Longitude ID number level) level) surface) unit u
78 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois S336 W-7 413622/871427 413622087142701 604 607.01 6- 9 UC WT

S337 W-9 413702/871320 413702087132001 597 597.98 3- 6 UC WTS338 122A 414017/872918 NA 588 590.81 2- 17 UC WTS339 122B 414017/872918 NA 588 590.48 23- 33 UC BS340 122C 414017/872918 NA 588 590.15 43- 48 UF CS341 127A 414022/872846 NA 589 591.51 3- 19 UC WTS342 127B 414022/872846 NA 590 591.78 27- 37 UC BS343 128A 414015/872858 NA 594 595.27 3- 18 UC WTS344 128B 414015/872858 NA 594 596.22 30- 40 UC BS345 130A 414009/872827 NA 589 591.67 2- 18 UC WTS346 130B 414009/872825 NA 589 591.70 28- 38 UC BS347 131A 413957/872837 NA 592 594.23 3- 18 UC WTS348 131B 413957/872838 NA 592 594.31 28- 38 UC MS349 132A 413953/872919 NA 586 588.14 3- 18 UC WTS350 133A 413940/872818 NA 592 593.80 3- 18 UC WTS351 133B 413940/872818 NA 592 594.13 30- 40 UC BS352 133C 413940/872818 NA 592 594.10 50- 55 UF CS353 136A 413906/872829 NA 586 587.95 1- 17 UC WTS354 136B 413906/872829 NA 586 588.26 26- 36 UC BS355 S41 413930/872956 NA 588 590.47 6- 22 UC WTS356 S53A 413940/872925 NA 586 588.82 4- 19 UC WTS357 S53B 413940/872925 NA 586 588.81 29- 34 UC BS358 S54A 413918/873024 NA 588 590.35 3- 18 UC WTS359 S54B 413918/873024 NA 588 590.37 26- 31 UC BS360 S56B 413854/873024 NA 590 593.14 26- 31 UC BS361 S57A 413851/872935 NA 585 587.04 2- 17 UC WTS362 S57B 413851/872935 NA 585 586.75 25- 30 UC BS363 S59A 413938/873030 NA 585 587.73 1- 16 UC WTS364 S59B 413938/873030 NA 585 587.60 24- 29 UC BS365 S63A 413924/872926 NA 587 589.27 1- 16 UC WTS366 S63B 413924/872926 NA 587 589.04 27- 32 UC BS367 S67A 413902/872926 NA 588 590.57 Unknown UCe WTS368 S67B 413902/872926 NA 588 590.04 Unknown UCe BCS369 S76B 413911/872959 NA 593 595.78 31- 37 UC BS370 S92A 413846/872928 NA 585 586.82 2- 18 UC WT

Land- Measuring 

surface point Screen altitude altitude interval 

(feet (feet (feet 

above above below 

Well Well Latitude/ USGS Site sea sea land Geologic Hydr

number name Longitude ID number level) level) surface) unit u
Appendix 1 79

S371 S92B 413846/872928 NA 585 586.57 26- 31 UC BS372 S93A 413842/872926 NA 586 588.81 2- 18 UC WTS373 S93B 413842/872926 NA 587 588.76 26- 31 UC BS374 S96A 413846/873009 NA 584 586.52 2- 18 UC WTS375 S96B 413846/873009 NA 584 586.45 22- 27 UC BS376 S97A 413839/873011 NA 584 586.36 2- 18 UC WTS377 S97B 413839/873011 NA 584 586.34 21- 26 UC BS378 1 413859/872840 NA 587 588.41 10-20e UCe WTS379 2 413854/872841 NA 589 589.22 10-20e UCe WTS380 MW-2 413859/873129 NA 587 587.51 4- 15 UC WTS381 MW-1 413859/873129 NA 587 587.26 69- 80 D SS382 MW-3 413859/873129 NA 585 587.42 13- 24 UC MS383 MW-8 413850/873130 NA 587 590.33 4- 15 UC WTS384 MW-9 413850/873130 NA 587 590.02 15- 26 UC BS385 MW-22 413850/873130 NA 587 591.74 39- 50 D SS386 1 413743/872611 NA 587 588.95 Unknown UCe CS387 2 413705/872603 NA 587 587.43 Unknown UCe CS388 3 413740/872705 NA 587 589.22 Unknown UCe CS389 MW-5 413650/872703 NA 588 590.13 16- 31 UC MS390 MW-10 413720/872701 NA 588 590.47 18- 33 UC MS391 MW-18 413850/872913 NA 586 586.21 Unknown UCe CS392 MW-30 413915/872918 NA 586 586.05 Unknown UCe CS393 MW-33 413915/872852 NA 588 588.63 Unknown UCe CS394 MW-34 413833/872922 NA 586 585.83 Unknown UCe CS395 MW-35 413841/872905 NA 586 586.26 Unknown UCe CS396 P-24 413846/872905 NA 585 584.86 Unknown UCe CS397 MW-1 414026/872955 NA 584 586.37 5- 29 UC WTS398 MW-2A 414021/872951 NA 584 585.71 Unknown UCe CS399 MW-3 414021/872942 NA 583 583.76 4- 28 UC WTS400 MW-5 414018/872951 NA 581 582.26 9- 24 UC WTS401 GM-4A 413451/872413 NA 611 612.97 4- 14 UC WTS402 GM-4B 413451/872413 NA 610 612.93 30- 35 UC BS403 MW-1 413510/872421 NA 604 606.50 8- 18 UC WTS404 MW-4 413451/872421 NA 609 611.91 6- 16 UC WTS405 2M 413629/872420 NA 586 588.60 Unknown UCe C

Land- Measuring 

surface point Screen altitude altitude interval 

(feet (feet (feet 

above above below 

Well Well Latitude/ USGS Site sea sea land Geologic Hydr

number name Longitude ID number level) level) surface) unit u
80 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois S406 3E 413630/872427 NA 586 586.26 Unknown UCe C

S407 3M 413630/872428 NA 586 586.80 Unknown UCe CS408 3W 413630/872428 NA 586 586.42 Unknown UCe CS409 5E 413634/872428 NA 586 585.56 Unknown UCe CS410 5W 413634/872428 NA 586 585.72 Unknown UCe CS411 6M 413632/872408 NA 586 586.46 Unknown UCe CS412 7E 413633/872412 NA 586 586.60 Unknown UCe CS413 7M 413633/872412 NA 586 586.48 Unknown UCe CS414 100 413822/872645 NA 588 587.62 Unknown UCe WTS415 105 413822/872646 NA 588 587.73 Unknown UCe WTS416 2 413606/872338 NA 595 594.98 Unknown UCe WTS417 3 413606/872339 NA 595 594.04 Unknown UCe WTS418 MW-8 413553/871026 NA 637 636.29 Unknown UCe WTS419 MW-12 413553/871024 NA 637 635.81 Unknown UCe CS420 OW-3 413434/871047 NA 638 637.84 Unknown UCe WTS421 OW-6 413433/871046 NA 638 637.24 Unknown UCe WTS422 W-1 413807/872820 NA 587 589.30 Unknown UCe CS423 W-2 413817/872818 NA 585 587.04 Unknown UCe CS424 W-3 413816/872820 NA 585 586.34 Unknown UCe CS425 W-4 413820/872824 NA 586 588.09 Unknown UCe CS426 W-5 413819/872819 NA 585 587.36 Unknown UCe CS427 W-6 413817/872831 NA 586 588.28 Unknown UCe CS428 W-7 1413816/872822 NA 588 589.54 Unknown UCe C

S429 CGA3 413722/872513 NA 590 591.87 Unknown UCe CS430 CGA4 413719/872519 NA 591 592.83 Unknown UCe CS431 MW-1A 413918/872713 NA 592 594.10 2- 13 UC WTS432 MW-1B 413918/872713 NA 592 593.24 22- 42 UC-UF BS433 MW-1C 413918/872713 NA 592 594.31 53- 63 UF MS434 MW-1D 413918/872713 NA 592 593.81 95-105 UF BS435 MW-6C 413950/872630 NA 597 598.60 10- 20 UC WTS436 MW-6D 413950/872630 NA 597 598.67 44- 54 UC-UF BS437 MW-6E 413950/872630 NA 595 596.41 73- 83 UF MS438 MW-6F 413950/872630 NA 595 596.66 124-134 UF BS439 MW-22A 414052/872526 NA 597 597.96 5- 20 UC WTS440 MW-22B 414052/872526 NA 597 598.07 40- 55 UC-UF B

Land- Measuring 

surface point Screen altitude altitude interval 

(feet (feet (feet 

above above below 

Well Well Latitude/ USGS Site sea sea land Geologic Hydr

number name Longitude ID number level) level) surface) unit u
Appendix 1 81

S441 MW-22C 414052/872526 NA 597 598.11 70- 80 UF MS442 MW-22D 414052/872526 NA 597 597.82 118-128 UF BS443 P-5B 413919/872620 NA 590 589.25 ?- 15 UC WTS444 P-13 414020/872554 NA 596 596.72 ?- 20 UC WTS445 P-14A 413947/872508 NA 594 595.63 9- 19 UC WTS446 P-24 414104/872527 NA 597 598.94 ?- 17 UC WTS447 MW-1 413423/872255 NA 607 610.39 6- 16 UC WTS448 MW-2 413423/872254 NA 607 610.25 24- 34 UC BS449 MW-16 413423/872255 NA 606 609.67 133-138 D SS450 MW-25 413405/872236 NA 594 595.06 Unknown UCe CS451 E-10 413511/872540 NA 609 611.21 5- 10 UC WTS452 E-30 413511/872540 NA 609 610.83 23- 28 UC BS453 E-200 413511/872540 NA 609 610.63 147-152 D SS454 F-10 413720/872426 NA 595 597.60 6- 11 UC WTS455 F-30 413720/872426 NA 595 597.64 41- 46 UC BS456 J-10 413724/872422 NA 601 603.37 17- 22 UC WTS457 J-30 413724/872422 NA 601 602.22 47- 52 UC BS458 K-10 413714/872440 NA 589 592.61 3- 8 UC WTS459 K-30 413714/872440 NA 589 592.07 36- 42 UC BS460 MW-G6A 413722/871006 NA 606 607.30 12- 22 UC WTS461 MW-G6C 413722/871006 NA 606 607.23 40- 50 UC BS462 MW-G6I 413722/871006 NA 606 607.07 76- 86 UC CS463 MW-G8A 413722/870948 NA 607 608.89 10- 20 UC WTS464 MW-G8C 413722/870948 NA 608 609.38 39- 49 UC CS465 MW-G8I 413722/870948 NA 608 609.02 68- 78 UC CS466 MW-G12A 413712/870935 NA 606 607.49 9- 19 UC WTS467 MW-G12C 413712/870935 NA 607 608.33 39- 49 UC CS468 MW-G12I 413712/870935 NA 607 607.89 81- 91 UC CS469 MW-L2A 413732/871038 NA 609 610.39 36- 46 UC MS470 MW-L2B 413732/871038 NA 609 610.26 62- 72 UC CS471 MW-L2C 413732/871038 NA 609 610.51 96-106 UC CS472 MW-L4A 413747/871041 NA 620 621.13 37- 47 UC MS473 MW-L4B 413747/871041 NA 621 621.55 49- 59 UC CS474 MW-L4C 413747/871041 NA 620 621.14 85- 95 UC CS475 MW-L5A 413721/871055 NA 605 605.83 15- 25 UC WT

Land- Measuring 

surface point Screen altitude altitude interval 

(feet (feet (feet 

above above below 

Well Well Latitude/ USGS Site sea sea land Geologic Hydr

number name Longitude ID number level) level) surface) unit u
82 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois S476 MW-L5B 413721/871055 NA 605 605.84 23- 33 UC M

S477 MW-L5C 413721/871055 NA 605 605.90 69- 79 UC CS478 MW-1 413831/872938 NA 585 590.36 Unknown UCe CS479 MW-2 413834/872938 NA 585 589.54 Unknown UCe CS480 MW-3 413834/872934 NA 585 589.64 Unknown UCe CS481 MW-4 413832/872937 NA 585 590.42 Unknown UCe CS482 MW-5 413832/872936 NA 585 589.98 Unknown UCe CS483 MW-6 413832/872938 NA 586 590.94 Unknown UCe CS484 MW-7 413833/872936 NA 585 590.35 Unknown UCe CS485 MW-8 413830/872938 NA 585 590.64 Unknown UCe CS486 MW-9 413832/872935 NA 585 590.42 Unknown UCe CS487 MW-10 413831/872936 NA 585 589.90 Unknown UCe CS488 W-11S 413541/872543 NA 601 603.27 3- 13 UC WTS489 W-12D 413541/872543 NA 601 602.66 16- 26 UC MS490 W-51S 413530/872543 NA 601 602.83 2- 12 UC WTS491 W-52D 413530/872543 NA 601 602.73 18- 28 UC MS492 MW-2 413809/870619 NA 610 609.86 5- 10 UC WTS493 MW-4 413809/871621 NA 610 609.62 5- 15 UC WTS494 MW-4D 413809/871621 NA 610 609.29 30- 35 UC MS495 OW-1 413809/870624 NA 610 610.31 5- 15 UC WTS496 BH-12 413620/872044 413620087204401 601 600.62 10- 20 UC WTS497 BH-13 413548/872040 413548087204001 603 602.92 9- 19 UC WTS498 BH-14 413445/872047 413445087204701 610 609.45 9- 19 UC WTS499 BH-15 414120/873047 414120087304701 585 584.56 10- 15 UC WTS500 BH-17 413706/871507 413706087150701 599 599.00 10- 20 UC WTS501 BH-19 413516/872223 413516087222301 602 601.56 10- 20 UC WTS502 BH-20 413615/872013 413615087201301 600 599.48 14- 24 UC WTS503 MW-1 414146/873043 NA 591 590.41 Unknown UCe WTS504 HWD2-5 413707/871726 NA 623 623.81 70- 90 UC BS505 HWD2-6 413706/871813 NA 607 609.22 50- 70 UC BS506 HWD2-7 413636/871751 NA 599 600.76 30- 50 UC BS507 HWD5-4 413810/872405 NA 592 594.08 11- 47 UC CS508 HWD5-5R 413813/872355 NA 592 594.62 ?- 47 UC CS509 HWT2-2 413750/872300 NA 602 603.81 16- 61 UC CS510 HWT2-4 413747/872251 NA 605 606.80 20- 65 UC C

Land- Measuring 

surface point Screen altitude altitude interval 

(feet (feet (feet 

above above below 

Well Well Latitude/ USGS Site sea sea land Geologic Hydr

number name Longitude ID number level) level) surface) unit u
Appendix 1 83

S511 HWT2-8 413758/872257 NA 588 589.68 30- 50 UC CS512 HWT2-9 413752/872234 NA 608 609.36 50- 70 UC CS513 HWT2-12S 413739/872251 NA 600 602.20 14- 29 UC CS514 HWT2-10 413730/872316 NA 589 591.25 24- 44 UC CS515 HWT2-11S 413743/872302 NA 604 605.64 15- 30 UC CS516 HWT13-1 413736/872233 NA 601 602.57 24- 60 UC CS517 HWT13-4 413741/872228 NA 602 603.75 26- 62 UC CS518 HWT14-1 413725/872250 NA 591 592.74 13- 49 UC CS519 HWT14-4 413729/872244 NA 591 592.07 ?- 48 UC CS520 HWT14-5 413721/872254 NA 589 590.79 27- 47 UC BS521 P-1 413649/871722 NA 601 603.10 19- 29 UC MS522 P-2 413658/871731 NA 615 616.36 30- 40 UC MS523 P-3 413650/871744 NA 615 616.98 29- 39 UC MS524 P-4 413743/872238 NA 602 603.85 25- 35 UC MS525 P-6 413744/872250 NA 605 606.92 20- 30 UC MS526 P-11 413736/871722 NA 596 596.94 15- 25 UC WTS527 P-12 413725/872241 NA 593 594.80 10- 20 UC WTS528 P-14 413751/872404 NA 590 592.23 10- 20 UC WTS529 P-16 413801/872353 NA 595 597.09 15- 25 UC WTS530 G-6 413821/870625 413821087062501 619 620.87 5.4- 10.4 UC WT

Land- Measuring 

surface point Screen altitude altitude interval 

(feet (feet (feet 

above above below 

Well Well Latitude/ USGS Site sea sea land Geologic Hydr

number name Longitude ID number level) level) surface) unit u
1Latitude/longitude determined by TRC Environmental Corporation by use of global positioning.

2Viscous oil found in well, did not allow measurement of water level.

Measuring p

altitude 

Station USGS site (feet abov

number Location Latitude/Longitude ID number sea leve

SW-1 Calumet Harbor 414302/873133 NA 580.45 SW-2 Calumet River at 106th Street 414210/873247 NA 607.66 SW-3 Calumet River at Torrence Avenue 414010/873338 NA 607.66 SW-4 Lake Calumet at Stony Island Avenue 413950/873432 NA 584.66 SW-5 Lake Calumet west 413957/873521 NA 584.41 SW-6 Calumet Sag Channel at Crawford Avenue 413904/874301 NA 613.59 SW-7 Little Calumet River at Halsted Avenue, Calumet Park 413921/873825 05536366 614.60 SW-8 Little Calumet River at Indiana Avenue 413900/873700 NA 601.16 SW-9 West side Wolf Lake 413953/873222 D4D9250 580.45 SW-10 Wolf Lake at Hammond 414016/873038 NA 584.55 SW-11 Lake George at Hammond 414022/873019 NA 584.27 SW-12 Grand Calumet River at Hohman Avenue 413728/872310 05536350 575.00 SW-13 Grand Calumet River at Calumet Avenue 413714/873032 NA 584.69 SW-14 Grand Calumet River at Indianapolis Boulevard 413651/872850 NA 595.39 SW-15 Lake Mary at Hammond 413841/872937 NA 582.46 SW-16 Indiana Harbor Canal at East Chicago 413904/872757 NA 581.22 SW-17 Unnamed Lake near Buffington Harbor 413809/872532 NA 586.30 SW-18 Grand Calumet River at Gary Regional Airport 413640/872513 NA 585.04 SW-19 Grand Calumet River at US 12 413629/872339 04092677 580.00 SW-20 Grand Calumet River at Bridge Street 413632/872219 NA 600.02 SW-21 Gary Harbor 413632/871925 NA 589.23 SW-22 Grand Calumet River near Broadway Street 413627/871920 NA 589.99 SW-23 Calumet Lagoons at Gary 413645/871733 NA 588.15 SW-24 Little Calumet River at Porter 413718/870513 04094000 603.48 SW-25 Little Calumet River at State Road 249 413644/871025 NA 604.45 SW-26 Little Calumet River at State Road 51 413513/871425 NA 603.09 SW-27 Little Calumet River at Gary 413419/871613 04093200 580.00 SW-28 Little Calumet River at Broadway Street 413339/872012 NA 603.27 SW-29 Little Calumet River at Colfax Street 413350/872447 NA 601.91 SW-30 Hart Ditch near Munster 413340/872850 05536190 591.27 SW-31 Little Calumet River at Munster 413407/873118 05536195 580.72 SW-32 Little Calumet River at Torrence Avenue 413538/873318 NA 605.64 SW-33 Little Calumet River at Cottage Grove Avenue 413625/873552 05536290 575.00 SW-34 Little Calumet River at Halsted Avenue, Harvey 413745/873825 NA 601.18 

84 Geohydrology in Northwestern Indiana and the Lake Calumet Area of Northeastern Illinois