U.S. Department of the Interior

U.S. Geological Survey

Ground-Water Quality Atlas of Oakland County, 

Michigan

Water-Resources Investigation Report 00-4120

Prepared in cooperation with the

Oakland County Health Division
Ground-Water Quality Atlas of Oakland County, 

Michigan

By Stephen Scranton Aichele

U.S. Geological Survey

Water-Resources Investigation Report 00-4120

Lansing, Michigan

August, 2000

 
U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

Any use of firm, brand, or trade names in this publication is

 for descriptive purposes only and does not constitute 

endorsement by the U.S. Government.

For additional information write: Copies of this report can purchased from:

District Chief U.S.Geological Survey

U.S. Geological Survey Branch of Information Services

6520 Mercantile Way, Ste. 5 Box 25286

Lansing, MI 48911-5991 Denver, CO 80225-0286 
CONTENTS Page

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

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

Purpose and scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Study-area description – Oakland County, Michigan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Population growth and land-use change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Water supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Surface-water resources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Surficial geology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Ground-water resources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Sites of USGS ground-water-quality sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Ground-water quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Sample collection and analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Field-measured characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Inorganic chemical constituents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Nutrients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Potential health effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Major ions and trace metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Chloride . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Occurrence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Potential health effects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Occurrence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Potential health effects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

Results of time-series analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

Results of replicate sample analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

References cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

Appendix 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

Appendix 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49

iii
CONTENTS--Continued Page

Figures 

Figure 1 - 10 Maps showing:

1. Rate of population growth in Oakland County, Michigan, from 1990 through 1998 . . . . . . . . . . . . .5

2. Principal sources of drinking water, by municipality, in Oakland County, Michigan in 1999 . . . . . . .7

3. Surface-water drainage basins of Oakland County, Michigan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

4. Surficial geology of Oakland County, Michigan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

5. Minimum soil permeability in Oakland County, Michigan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

6. Elevation of the water-table surface in Oakland County, Michigan . . . . . . . . . . . . . . . . . . . . . . . . . .15

7. Sites of U.S. Geological Survey ground-water-quality sampling in Oakland County, Michigan . . . .17

8. Nitrate distribution in Oakland County, Michigan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

9. Chloride distribution in Oakland County, Michigan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

10. Arsenic distribution in Oakland County, Michigan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Tables

1. Land use in Oakland County as a percentage of total county area, 1978 and 1995 . . . . . . . . . . . . . . . .4

2. Water-quality characteristics analyzed by the USGS National Water

Quality Laboratory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

3. Inorganic constituents analyzed in this study with USEPA drinking water standards . . . . . . . . . . . . .20

4. Summary statistics for selected inorganic constituents detected in water samples from selected

 wells in Oakland County. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Appendix 1: Water-quality data collected by the U.S. Geological Survey in Oakland 

County, Michigan, 1998 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

Tables

1A. Index of station names with U.S. Geological Survey station identification numbers . . . . . . . . . .36

1B. Field measurements of water-quality characteristics for ground-water samples from selected

wells in Oakland County, Michigan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

1C. Results of analyses for selected inorganic chemical constituents in ground-water samples 

from selected wells in Oakland County, Michigan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

1D. Seasonal comparison of selected water-quality parameters for samples from selected wells

in Oakland County, Michigan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44

1E. Total arsenic concentrations in drinking water at selected ground-water sampling 

sites in Oakland County, Michigan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46

1F. Total manganese concentrations in drinking water at selected ground-water sampling 

sites in Oakland County, Michigan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

1G. Total iron concentrations in drinking water at selected ground-water sampling 

sites in Oakland County, Michigan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48 

iv
CONTENTS--Continued Page

Appendix 2: Results of replicate sample analyses by U.S. Geological Survey National Water 

Quality Laboratory and the Michigan Department of Environmental Quality Drinking Water 

Laboratory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49

Figures

2A. Graph showing nitrate concentrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

2B. Graph showing chloride concentrations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

2C. Graph showing arsenic concentrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

Tables

2A. Analytical results of nitrate and nitrite analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51

2B. Analytical results of chloride analyses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

2C. Analytical results of arsenic analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

 

v
CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATIONS

MULTIPLY BY TO OBTAIN

inches (in) 25.4 millimeters (mm)

foot (ft) 0.3048 meters (m)

mile (mi) 1.609 kilometer (km)

cubic foot (ft3) 0.02832 cubic meter (m3)

gallon 3.785 liter (L)

Temperature is given in degrees Celsius (o

C), which can be converted to degrees Fahrenheit (oF) 

by the following equation: o

F = 32 + (oC * 1.8)

Sea level: In this report, “sea level” refers to the National Geodetic Vertical Datum of 1929 (NGVD of 

1929)- a geodetic datum derived from a general adjustment of the first-order level nets of the United States 

and Canada, formerly called Sea Level Datum of 1929.

milligrams per liter (mg/L) or micrograms per liter (μg/L): Milligrams per liter is a unit expressing the 

concentration of chemical constituents in solution as weight (milligrams) of solute per unit volume (liter) 

of water. One thousand micrograms per liter is equivalent to one milligram per liter. For concentrations 

less than 7,000 mg/L, the numerical value is the same as for concentrations in parts per million.

ABBREVIATIONS (in addition to those above)

DO, concentration of dissolved oxygen

SC, specific conductance

DS, dissolved solids

MRL, minimum reporting level

MCL, maximum contaminant level

SMCL, secondary maximum contaminant level

μS, microsiemens 

cm, centimeter

μg, microgram

mm, millimeter

mg, milligram

L, liter

mV, millivolts

eH, oxidation-reduction potential in mV

pH, negative logarithm of the concentrations of hydrogen ions

vi
1

By Stephen Scranton Aichele

ABSTRACT

The U.S. Geological Survey (USGS), in 

cooperation with Oakland County Health Division (OCHD), collected 140 water samples 

from 38 wells in Oakland County during 1998 

to better understand ground-water quality. 

OCHD had observed temporal variations in 

concentrations of various constituents, so two 

additional sets of samples were collected to 

evaluate potential short-term variability related 

to sample collection procedures and long-term 

seasonal variability. Replicate samples from 

28 wells were analyzed in the Michigan 

Department of Environmental Quality 

(MDEQ) Drinking Water Laboratory to compare MDEQ’s analytical results to those 

obtained from the USGS National Water Quality Laboratory. Several additional databases 

describing population, land use, water supply, 

soils, geology, and flows of ground water and 

surface water are presented in the first part of 

the report to assist in interpreting the waterquality data. Maps created from these databases are provided in the first portion of the 

report as an extension of the study-area 

description.

The U.S. Environmental Protection 

Agency (USEPA) has established Maximum 

Contaminant Levels (MCL) and Secondary 

Maximum Contaminant Levels (SMCL) for 

which samples were analyzed in this study. 

Water from the 38 wells sampled by the USGS 

did not exceed the SMCL or MCL for sulfate, 

fluoride, or nitrite. However, water from 26 

wells exceeded the SMCL for iron, water from 

12 wells exceeded the SMCL for manganese, 

and water from 12 wells exceeded the SMCL 

for dissolved solids. Water from two wells 

exceeded the MCL for nitrate, although nitrate 

concentrations in water from most wells was 

below the detection limit. Water from seven 

wells exceeded the SMCL for chloride, and 

water from all wells contained detectable concentrations of chloride. Water from five wells 

exceeded the MCL for arsenic, and most of the 

wells sampled contained detectable concentrations of arsenic. These five wells were identified from previous MDEQ analyses to have 

elevated arsenic concentrations, and were sampled to obtain additional chemistry information. Replicate samples were collected from 

26 of the 38 wells for analysis at the MDEQ 

Drinking-Water Laboratory to compare the 

results with the USGS National Water Quality 

Laboratory. The results of the replicate analyses indicate close agreement between the laboratories, with mean differences for nitrate, 

chloride, and arsenic of 0.10 milligrams per 

liter (mg/L) as nitrogen, 6.8 mg/L, and 0.0008 

mg/L, respectively between the USGS and 

MDEQ analyses. Potential health effects associated with ingesting nitrate, chloride, and 

arsenic are provided with the water-quality 

data, along with references for further information.

INTRODUCTION

In 1996, the U.S. Geological Survey 

(USGS), in cooperation with the Michigan 

Department of Environmental Quality 

(MDEQ), the University of Michigan, and nine 

counties in southeastern Michigan, began a

Ground-Water Quality Atlas of Oakland County, Michigan
2

study of the occurrence and distribution of 

arsenic in ground water in southeastern Michigan. The early results of this study raised 

broader concerns in Oakland County about the 

quality of ground water used for drinking 

water. In response to these concerns, the 

USGS, in cooperation with the Oakland 

County Health Division (OCHD) initiated a 

study of distributions of arsenic, nitrate, and 

chloride in ground water in Oakland County. 

A series of USGS Fact Sheets were produced 

in December 1998 to present maps and information to residents of Oakland County about 

the distribution and potential health effects of 

these chemicals in ground water.

Understanding the distribution of these 

chemicals required the compilation of several 

supporting data sets describing the geologic 

and hydrologic setting of Oakland County. 

These data sets are presented in the first part of 

this report. Water samples from 38 wells 

across Oakland County were analyzed for 

arsenic, nitrate, chloride, and more than 20 

additional physical and chemical characteristics. Complete analytical results are provided 

in Appendix 1. A comparison of analytical 

results from the USGS National Water-Quality 

Laboratory (NWQL) and the MDEQ Drinking 

Water Laboratory is presented in Appendix 2.

Purpose and Scope

This report provides information on the 

distribution of arsenic, nitrate and chloride in 

ground water in Oakland County and the 

potential health effects of each chemical. Analytical results are presented for water samples 

collected by the USGS in Oakland County in 

1998, as well as several supporting spatial 

databases describing the demographic, geologic, and hydrologic context of Oakland 

County. This report also provides several 

maps, generated by the Center for Applied 

Environmental Research at the University of 

Michigan-Flint (CAER) from information in 

MDEQ databases, to describe the occurrence 

of arsenic, nitrate, and chloride in ground 

water. 

Acknowledgments

The author gratefully acknowledges the 

assistance of Dr. Thomas Gordon, Robert 

Long, and Karen Kubik of Oakland County 

Health and Human Services in obtaining historical data, coordinating access to sample 

sites, and providing background information 

for interpreting the water-quality data. Scott 

Oppmann and Brian Ely of the Oakland 

County GIS Utility provided digital base map 

data with municipal boundaries. Dr. Richard 

Hill-Rowley and Matt Malone of CAER provided assistance with validating and geocoding 

the MDEQ database, as well as with strategies 

for mapping the data at the county scale. Thomas McClain of the CAER mapped the elevation of the water-table surface. 
3

STUDY-AREA DESCRIPTION – 

OAKLAND COUNTY, MICHIGAN

A variety of spatial databases were generated or modified for use in this

study, and are presented in the next several pages to provide a context for

the study. Included are descriptions of the glacial geology, soils, surfaceand ground-water resources, as well as summary information about wateruse, population growth, and land-use change in Oakland County. Oakland

County, with a land area of 900 square miles, contains 25 survey townships

and is the largest county in the Lower Peninsula of Michigan. With more

than 1.2 million residents, Oakland County is the second most populous

county in Michigan.

OAKLAND

COUNTY
4

Population Growth and Land-Use Change 

Oakland County has grown dramatically in the last several decades. The

Southeast Michigan Council of Governments (SEMCOG) provides estimates of

actual population based on information from county and local governments to

supplement Census data. The population has increased from about 700,000 in

1960 to nearly 1.2 million in 1998. The rate of population growth has been relatively consistent, with the population increasing by more than 100,000 people per

decade. Population growth has not been spatially uniform (fig. 1). Population

growth between 1990 and 1998 has exceeded 60 percent in some municipalities,

and has exceeded 20 percent in 18 of 58 minor civil divisions (Southeast Michigan Council of Governments, 1999). 

The expansion of residential areas resulting from the increase in population

has resulted in marked changes in land use. A comparison of land-use data compiled by the Michigan Department of Natural Resources (1978) and SEMCOG

data compiled in 1995 indicates an increase in urban land use, primarily residential, accompanied by decreases in agricultural land, pasture land, and forest land

(table 1). While some of these differences may be because of differences in the

methods of compilation between agencies (specifically identification of wetlands

in the ‘Other’ category), the trend is toward increasing allocation of land for urban

use, with decreasing allocation for agriculture, forest, and pasture.

Table 1. Land use in Oakland County as a 

percentage of total county area, 1978 and 1995

The effects of human activities on water resources, whether ground water or

surface water, are complex (Winter and others, 1998). The increased proportion

of the county devoted to urban and residential land uses is accompanied by more

wells that extract water, more impervious surfaces that block or redirect recharge,

and more storm drains that divert precipitation into streams instead of aquifers.

Over time, this can alter the availability and quality of hydrologic resources, both

ground water and surface water, in Oakland County. Modifications in land use

may also affect the proportions of ground water and surface runoff in rivers and

streams, which can affect the chemistry, temperature, and general quality of the

water for wildlife and for recreation. The need to better understand how the

increased use of water for agriculture, recreation, and residential household uses

affects ground-water and surface-water resources will surely increase as development intensifies (Winter and others, 1998).

Land use 1995 

(percent)

1978 

(percent)

Urban 48.7 39.3

Agriculture 11.7 15.0

Pasture 16.2 21.3

Forest 8.4 13.7

Other 15.0 10.7
R. 7 E. R. 8 E. R. 9 E. R. 10 E. R. 11 E.

T. 1 N.

T. 2 N.

T. 3 N.

T. 4 N.

T. 5 N.

FARMINGTON

PONTIAC AVON

HOLLY

GROVELAND

BRANDON

Ortonville

Oxford

OXFORD

ADDISON

Leonard

ROSE

SPRINGFIELD

INDEPENDENCE

Clarkston ORION

Lake Orion

OAKLAND

Rochester Hills

Pontiac

Auburn Hills

HIGHLAND WHITE LAKE WATERFORD

Holly

MILFORD

Milford COMMERCE

Wixom

Wolverine Lake

Orchard Lake Village

WEST BLOOMFIELD

TROY

NOVI

Farmington Hills

SOUTHFIELD

LYON

Rochester

Lake Angelus

South Lyon

Northville 

Farmington

Franklin Beverly Hills

Walled Lake

Bloomfield 

Hills

BLOOMFIELD

Royal Oak

Ferndale

Clawson

Lathrup Village

Bingham Farms

Birmingham

Madison Heights

Huntington Woods

Berkley

Hazel Park

ROYAL OAK

Oak Park

Pleasant Ridge

Source:

Population data provided by Southeast Michigan Council of Governments (1999).

Figure 1. Rate of population growth in Oakland County, Michigan, from 1990 through 1998. 

0 5 10 Miles

0 5 10 15 Kilometers

EXPLANATION

Growth Rate (1990-1998)

0 - 20 percent

20.1 - 40 percent

40.1 - 65 percent
6

Water Supply 

Most of Oakland County is served by public water supplies. These supplies

are subject to regulation by Federal, State, and other authorities to ensure the

water produced meets public health standards. The Detroit Water and Sewerage

Department (DWSD) provides 137 million gallons per day (MGD) of water to the

southeastern townships of Avon (Rochester Hills), Pontiac, Troy, Bloomfield,

West Bloomfield, Royal Oak, Southfield, Farmington, Novi and Commerce (fig.

2). Several additional mains have been constructed to provide water to adjoining

areas. Water provided by DWSD is drawn from Lake Huron and Lake St. Clair, as

well as the St. Clair River and Detroit River.

More than 140 smaller community supplies use ground-water resources to

provide 21.4 MGD to more than 160,000 residents (C. Luukkonen, USGS, written

commun., 1999). The communities served by these supplies range in size from

Waterford Township, with a population of more than 70,000 (Southeast Michigan

Council of Governments, 1999), to individual subdivisions, with only a few

homes. More than 233,000 Oakland County residents are not connected to public

water supplies, but obtain water from domestic wells. These withdrawals amount

to approximately 16.7 MGD (C. Luukkonen, USGS, written commun., 1999).

Domestic wells are not currently monitored by any governmental agency, and are

the responsibility of the owner. 

Interior of a community water supply pump house in 

Oakland County, Michigan. Community water supplies

like this one provide water to over 160,000 residents.
ROYAL OAK

BLOOMFIELD

LYON

NOVI

TROY

WEST BLOOMFIELD

COMMERCE

MILFORD

WATERFORD WHITE LAKE HIGHLAND

OAKLAND

Lake Orion

ORION

INDEPENDENCE

SPRINGFIELD

ROSE

ADDISON

OXFORD

BRANDON

GROVELAND

HOLLY T. 5 N.

T. 4 N.

T. 3 N.

T. 2 N.

T. 1 N.

R. 7 E. R. 8 E. R. 9 E. R. 10 E. R. 11 E.

AVON PONTIAC

FARMINGTON

SOUTHFIELD

ROYAL OAK

Source: Water supply information obtained in consultation with Oakland County Health Division and local suppliers.

Surface-water supplies

Ground-water supplies

EXPLANATION

Figure 2. Principal sources of drinking water, by municipality, in Oakland County, Michigan in 1999. Sources 

of drinking water for individual structures or uses may vary.

0 5 10 Miles

0 5 10 15 Kilometers
8

Surface-Water Resources 

Surface-water resources abound in Oakland County. More than 1,600 lakes

of varying sizes were recorded in a 1958 inventory (Humphrys, 1962). A substantial number of these lakes are large enough for recreational use, such as boating,

swimming, and fishing. Most of these lakes receive water from ground water

most of the year (Mozola, 1954). 

Oakland County spans the headwaters of six major rivers (fig. 3). The Shiawassee and Flint Rivers drain the northwestern part of the County, eventually

joining the Saginaw River to flow into Lake Huron. The Huron River drains the

southwestern part of the county, delivering the water to Lake Erie. The Clinton

River in the north and the River Rouge in the south drain the central and southeastern parts of the county into Lake St. Clair and the Detroit River. The Belle

River drains a very small area (less than 1 sq. mi.) of Addison Township. More

than half of the water flowing in these rivers over the course of a year is groundwater discharge to the river through the streambed (Holtschlag and Nicholas,

1998). 

The 1,600 lakes in Oakland County are important hydrologic and recreational 

resources.
R. 7 E. R. 8 E. R. 9 E. R. 10 E. R. 11 E.

T. 1 N.

T. 2 N.

T. 3 N.

T. 4 N.

T. 5 N.

ROYAL 

OAK

SOUTHFIELD

FARMINGTON NOVI

LYON

BLOOMFIELD TROY

WEST 

BLOOMFIELD

COMMERCE MILFORD

AVON PONTIAC

WATERFORD WHITE

LAKE HIGHLAND

OAKLAND ORION

INDEPENDENCE

SPRINGFIELD

ROSE

ADDISON OXFORD BRANDON HOLLY GROVELAND

Source: Municipal boundaries provided by Oakland County GIS Utility. Hydrologic divides from MDEQ Land and Water Management.

Hydrologic features from MiRIS.

Figure 3. Surface-water drainage basins of Oakland County, Michigan. Drainage to Belle River 

not shown due to scale constraints.

Drainage basins

Drainage to Clinton River

Drainage to Huron River

Drainage to River Rouge

Drainage to Flint River

Drainage to Shiawassee River

Municipal boundaries

Rivers and streams

Sub-watershed divides

EXPLANATION

0 5 10 Miles

0 5 10 15 Kilometers
10

Surficial Geology 

Nearly all of the hills and lakes in Oakland County were formed during the

retreat of the last continental glacier, approximately 14,000 years ago (Winters

and others, 1985). For the preceding 60,000 years, the area that is now Oakland

County was intermittently covered by as much as a mile of ice. During the retreat

of the ice, an ice-free area formed between the Saginaw Lobe in the northern part

of the county and the Huron-Erie Lobe to the south (fig. 4), the axis of which

tracks through Commerce, Waterford, and Oxford (Leverett and Taylor, 1915;

Winters and others, 1985). This area formed a conduit for large quantities of

water and sediment flowing off the melting glacier, known as outwash. Outwash

environments deposit sorted sediments, so that materials of a certain size and

composition are layered vertically and are exposed together on the landscape. A

broad outwash plain (shown in yellow in figure 4) stretches across central Oakland County from northeast to southwest.

On either edge of the outwash plain region are areas of moraine and other

types of till (shown in green hues in figure 4), deposited directly by the ice at the

margins of the glacial lobes. The materials in these features are unsorted, and

include clays, sands, pebbles, and boulders. These areas usually have much

higher clay fractions than the outwash plain region, which results in lower permeability. 

Following the retreat of the ice back to the Great Lakes basins, large lakes

formed from meltwater occurred at much higher elevations than the current elevations of the Great Lakes (Eschman and Karrow, 1985). The beds of these lakes

collected clays and other sediments in broad blankets. The highest of these lakes

in the Huron-Erie basin was Lake Maumee, which maintained an elevation

between 775 and 810 ft above sea level (covering much of southeastern Oakland

County) for a period of approximately 300 years starting 14,000 years ago

(Eschman and Karrow, 1985). The beds of these proglacial lakes are evident in

the flat-lying, clay-rich sediments of southeastern Oakland County (shown in gray

tones in figure 4). These clay-rich sediments have dramatically lower permeability than the outwash sediments.

The thickness of these glacial materials vary greatly across the county. The

thickness of the surficial sediments exceeds 400 feet across the central part of the

county, but can be less than 100 feet in the southeast and northwest corners

(Twenter and Knutilla, 1972). Throughout most of the county, the surficial

deposits are the primary aquifer. Fewer than 3 percent of the wells in the county’s

WELLKEY database are completed in bedrock. 

The underlying bedrock units throughout most of the county are not considered good sources of potable water, and water drawn from these units is frequently high in sulfate, iron, chloride, and dissolved solids. The Marshall

Sandstone is a productive bedrock aquifer for the northwestern townships of

Holly, Groveland, Brandon, and Rose. Even in this area, the vast majority of

wells are completed in the glacial sediments.
R. 7 E. R. 8 E. R. 9 E. R. 10 E. R. 11 E.

T. 1 N.

T. 2 N.

T. 3 N.

T. 4 N.

T. 5 N.

SAGINAW LOBE

HURON-ERIE LOBE

ROYAL 

OAK

SOUTHFIELD

FARMINGTON NOVI

LYON

TROY

BLOOMFIELD WEST 

BLOOMFIELD

COMMERCE

MILFORD

AVON PONTIAC

WATERFORD WHITE

LAKE HIGHLAND

OAKLAND ORION

INDEPENDENCE SPRINGFIELD

ROSE

OXFORD ADDISON BRANDON HOLLY GROVELAND

Glacial till

End moraines of glacial till

Glacial outwash sand and gravel

Lacustrine clay and silt

Lacustrine sand and gravel

Lakes

Municipal boundaries

EXPLANATION

Interlobate divide

Source: Geologic information modified from Ferrand and Bell(1982).

Interlobate divide modified from Winters and others (1985).

Figure 4: Surficial geology of Oakland County, Michigan.

0 5 10 Miles

0 5 10 15 Kilometers
12

Soils 

The soils of Oakland County are the direct result of the surficial geologic processes previously described. Physical and chemical characteristics reported by

the Soil Conservation Service (1982) show patterns similar to the surficial geology map shown previously.

Minimum soil permeability, for example, ranges over two orders of magnitude, from 0.06 inches/hour (in/hr) to 20 in/hr. The region with minimum infiltration rates of 6 in/hr or greater closely resembles the region mapped as outwash

(fig. 5). Infiltration rates directly affect the amount of recharge, and thus the

potential for transport of contaminants into an aquifer. The lowest permeability

soils correspond spatially to till and lake-bed sediments. High permeability,

sandy soils have been widely identified as being susceptible to contamination by

anthropogenic pollutants, such as nitrate (Kittleson, 1987; Fetter, 1994).

The chemical properties of the soils also reflect the surficial geologic processes. The highest concentrations of calcium carbonate in the soil are generally

clustered in regions formed of till. Calcium carbonate concentrations are generally lower in the outwash plain region located in the central part of the county.

Bicarbonate (HCO3

-

), an ion formed when calcium carbonate is dissolved by

infiltrating water, has been shown to encourage the dissolution of arsenic (Kim,

1999). 

The top several feet of soil contain different layers called horizons. 

The permeability of these horizons controls how quickly water and 

potential contaminants are transported into aquifers. (Photo courtesy of R.J. Schaetzl.)
R. 7 E. R. 8 E. R. 9 E. R. 10 E. R. 11 E.

T. 1 N.

T. 2 N.

T. 3 N.

T. 4 N.

T. 5 N. HOLLY GROVELAND BRANDON OXFORD ADDISON

ROSE

SPRINGFIELD

INDEPENDENCE

ORION OAKLAND

HIGHLAND

WHITE

LAKE WATERFORD PONTIAC AVON

MILFORD COMMERCE

WEST 

BLOOMFIELD

BLOOMFIELD TROY

LYON

NOVI FARMINGTON

SOUTHFIELD

ROYAL 

OAK

Minimum infiltration rate of soil pedon

(inches per hour)

6.0 in/hr or greater

Greater than 2.0 but less than 6.0 in/hr

Municipal boundaries

EXPLANATION

Figure 5. Minimum soil permeability rates in Oakland County, Michigan.

0 5 10 Miles

0 5 10 15 Kilometers

0.06 through 2.0 in/hr

Sources:

Soils information provided by Soil Conservation Service (1982).
14

Ground-Water Resources 

The CAER developed a map of ground-water levels in Oakland County (fig.

6), derived from the elevations of rivers and lakes and the elevations of ground

water in the glacial aquifer. Ground-water elevations were obtained from drillers’

logs and Oakland County’s WELLKEY database. Because the drillers’ logs were

collected over a period of several decades, the derived surface represents an

approximation over time, rather than a specific time. 

In general, the configuration of the water table is a subdued version of the

landscape topography. Accordingly, the water-level map developed by the CAER

shows a region of higher water levels along the northern edge of the outwash plain

region, corresponding to the part of Oakland County where the land surface is

highest. The high region in the water table surface forms a ground-water-flow

divide. Northwest of this divide, ground water generally flows towards Saginaw

Bay. Southeast of this divide, ground water generally flows toward Lake Erie and

Lake St. Clair.

This map represents the water levels in the glacial aquifer only. Evaluation of

Oakland County’s WELLKEY database indicates more than 97 percent (8,458 of

8,654) of the wells in the database are completed in the glacial aquifer. Several

examples of confined aquifers and artesian wells have been noted by authors in

the past (Mozola, 1954; Leverett and others, 1906). In these regions, water within

these confined systems may be under pressure, and would rise to a different level

than the level portrayed in figure 6.

Domestic wells like this one provide drinking water to more than

233,000 Oakland County residents.
R. 7 E. R. 8 E. R. 9 E. R. 10 E. R. 11 E.

T. 1 N.

T. 2 N.

T. 3 N.

T. 4 N.

T. 5 N.

1000

ROYAL 

OAK

SOUTHFIELD

FARMINGTON

NOVI

LYON

BLOOMFIELD TROY

WEST 

BLOOMFIELD

COMMERCE

MILFORD

AVON PONTIAC WATERFORD WHITE

LAKE HIGHLAND

OAKLAND ORION

INDEPENDENCE

SPRINGFIELD

ROSE

ADDISON OXFORD BRANDON GROVELAND HOLLY

850

900

900

1050

1000 1050

950

700

750

890

800

890

1050

850

Source: Elevation contours and flow divide produced by the Center for Applied Environmental 

Research at the University of Michigan - Flint.

800

Municipal boundary

Water-table contour. Elevation 

in feet above sea level. Contour 

interval 50 feet.

Ground-water flow divide

EXPLANATION

Figure 6. Elevation of the water-table surface in Oakland County, Michigan.

0 5 10 Miles

0 5 10 15 Kilometers
16

Sites of USGS Ground-Water-Quality Sampling 

The USGS collected water samples from 68 wells in Oakland County in 1997

and 1998 (fig 7). Thirty of these wells were sampled as part of ongoing USGS

activities. The results of these analyses are presented in Blumer and others

(1998).

Thirty-eight wells were sampled specifically for this project between June and

December 1998. These wells were selected for several reasons. All selected

wells had a previous water quality analysis in the Michigan Department of Environmental Quality (MDEQ) database. The water from approximately half of

these wells had exceeded at least one U.S. Environmental Protection Agency

(USEPA) Maximum Contaminant Level (MCL) or Secondary MCL (SMCL) on

at least one occasion. Additional wells with previous water chemistry information

and lower concentrations of the chemical constituents of concern were selected in

the vicinity of the wells with exceedances of the regulatory contaminant levels.

All but six of the wells selected for sampling were privately owned domestic

water wells supplying a single-family dwelling. Two of the selected wells supplied water to institutions, one to a restaurant, one to a car wash, one to a community water supply, and one to a government building. Well depths, obtained from

well construction logs when available, are included in appendix table 1C.

Two additional sets of samples were collected in December 1998. Each set

included samples from five wells, which were selected on the basis of results of

previous USGS and MDEQ water-quality analyses. These samples were collected to evaluate possible short- and long-term variation in water quality.

Sampling equipment in use outside a community water supply well in

Oakland County, Michigan.
$

$

$

$

$

$

$

$$

$

$ $ $

$

$

$

$$ $

$

$$

$$

$

$ $

$

$

$

$

$

$

$

$

$

$$

$

$ $ $ $ $ $

$ $

$ $ $

$ $

$

$

#

OAK 11 #

OAK 17 # OAK 10

#

OAK 12 #

OAK 9

#

OAK 43

#

OAK 42 #

OAK 3

#

OAK 4

#

OAK 2

# OAK 1 #

OAK 19 #

OAK 25 #

OAK 26

#

OAK 24A

#

OAK 35

#

OAK 21

#

OAK 15 #

OAK 8

#

OAK 31

#

OAK 14

#

OAK 16

#

OAK 39

#

OAK 40

#

OAK 7

#

OAK 33 #

OAK 41

#

OAK 32

#

OAK 38

#

OAK 34

# OAK 37

#

OAK 30

#

OAK 29

#

OAK 20

# OAK 36

#

OAK 24

#

OAK 23 #

OAK 22

R. 7 E. R. 8 E. R. 9 E. R. 10 E. R. 11 E.

T. 1 N.

T. 2 N.

T. 3 N.

T. 4 N.

T. 5 N. HOLLY GROVELAND BRANDON

OXFORD

ADDISON

ROSE

SPRINGFIELD INDEPENDENCE ORION

HIGHLAND WHITE

LAKE

WATERFORD PONTIAC AVON

MILFORD COMMERCE

WEST 

BLOOMFIELD BLOOMFIELD

TROY

LYON

NOVI

FARMINGTON

SOUTHFIELD

ROYAL 

OAK

OAKLAND

Municipal boundaries

$ USGS ground-water sampling sites

used for this study

EXPLANATION

$ Ongoing USGS ground-water sampling sites

Figure 7. Sites of U.S. Geological Survey ground-water-quality sampling in Oakland County, Michigan.

0 5 10 Miles

0 5 10 15 Kilometers
18

GROUND-WATER QUALITY

The ground-water quality investigation in Oakland County included field analysis of physical 

characteristics, as well as laboratory analysis for 

nutrients, major inorganic ions, and selected trace 

metals. A brief discussion of the methods and 

results of each type of analysis will be presented, 

along with a table of summary statistics. The complete results are provided in table 1C of Appendix 

1. More detailed discussions of the geochemistry 

and the potential health effects of nitrate and 

arsenic are included to assist Oakland County and 

local governments in water-resource management 

issues specific to these chemicals. 

Sample collection and analysis 

All samples were collected using the clean 

sampling procedures specified by the USGS 

National Water-Quality Assessment (NAWQA) 

program (Shelton, 1994). Unsoftened water samples were collected from domestic wells by connecting to external, garden hose taps. All tubing 

used in sample collection was Teflon-lined, with 

high-density poly-ethylene (HDPE) or Teflon fittings and connectors. Physical characteristics 

(temperature, specific conductance, dissolved oxygen, pH, eH) were measured at the well-site with a 

Hydrolab H20 connected in-line through a flowthrough cell. Before a ground-water sample was 

collected for laboratory analysis, wells were 

purged for a period of at least 20 minutes until the 

above field characteristics had stabilized. Stability 

was determined on the basis of the following criteria; specific conductance variation less than 

2 μS/cm, pH variation less than 0.05 pH units, dissolved oxygen variation less than 0.05 mg/L, and a 

temperature variation of less than 1oC. Alkalinity 

titrations were performed on filtered samples in the 

field.

All wells were sampled for analysis of major 

cations, major anions, nutrients, and arsenic. A 

complete list of laboratory analyses is included in 

table 2. The USGS National Water Quality Laboratory (NWQL) in Arvada, Colorado performed all 

analyses listed in table 2. 

At 26 sites, replicate samples were collected 

for analysis by the MDEQ. These samples were 

collected to examine the comparability of MDEQ 

analytical results for arsenic, nitrate, and chloride 

to results from the USGS NWQL. The MDEQ laboratory uses an inductively coupled plasma mass 

spectrometry (ICPMS) method for arsenic analyses 

(MRL = 0.0001 mg/L), and colorimetric methods 

for nitrate (MRL = 0.4 mg/L) and chloride

(MRL = 4 mg/L) analyses.

Five wells were selected to provide information on long-term seasonal variations in groundwater quality. These wells were sampled using 

methods identical to those described previously for 

the collection of ground-water-quality samples.

Five wells were sampled to evaluate short-term 

(0 - 25 minutes) variations in chemical composition of drinking water. Operationally, drinking 

water is distinguished from ground water by the 

fact that the well and plumbing system are not 

purged before sample collection. The sample is 

thus reflective of what a resident might consume if 

simply getting a glass of water. Sampling procedures were designed to evaluate potential changes 

in concentrations of arsenic, manganese, and iron 

within a domestic plumbing system. Four wells 

were selected on the basis of detection of arsenic, 

manganese, and iron in samples analyzed at the 

NWQL. One well, OAK 41, was added to this 

sample group because of extensive prior data on 

record at MDEQ. At wells selected for the shortinterval, time-series sample collection, unfiltered 

samples were collected at intervals ranging from 

30 seconds to 2 minutes for the first 20 to 25 minutes of well pumping. Wells were not purged prior 

to collecting the first sample. These samples were 

analyzed for total arsenic using a flame atomic 

absorption method (Brown, 1998). Manganese and 

iron were analyzed using an ICPMS method (Garbarino and Struzeski, 1998).

Field-Measured Characteristics

Temperature, specific conductance, oxidationreduction potential (eH), dissolved oxygen (DO), 

pH, and alkalinity were measured in the field. 

Results of these analyses are shown in appendix 

table 1B. No health standards exist for any of these 

constituents, but the USEPA has issued a Secondary Maximum Contaminant Level for pH based on 

aesthetic considerations. 
19

Table 2: Water quality characteristics analyzed by the USGS National Water Quality Laboratory 

[μS/cm, microsiemens per centimeter at 25 degrees Celsius; oC, degrees Celsius; mg/L, milligrams per liter]

Parameter name Units MRL Parameter 

code

Method Reference

Specific Conductance μS/cm 1 90095 I278185 Fishman and Friedman, 1989

pH, Laboratory Standard Units 0.1 403 I258785 Fishman and Friedman, 1989

Total Residue @ 180 oC mg/L 1 530 I376585 Fishman and Friedman, 1989

Calcium, dissolved mg/L as Ca 0.02 915 I147287 Fishman and Friedman, 1989

Magnesium, dissolved mg/L as Mg 0.004 925 I147287 Fishman, 1993

Sodium, dissolved mg/L as Na 0.06 930 I147287 Fishman, 1993

Potassium, dissolved mg/L as K 0.1 935 I163085 Fishman and Friedman, 1989

Acid Neutralizing Capacity mg/L as CaCO3 1.0 90410 I203085 Fishman and Friedman, 1989

Sulfate, dissolved mg/L as SO4 0.1 945 I205785 Fishman and Friedman, 1989

Chloride, dissolved mg/L as Cl 0.1 940 I205785 Fishman and Friedman, 1989

Flouride , dissolved mg/L as F 0.1 950 I232785 Fishman and Friedman, 1989

Bromide, dissolved mg/L as Br 0.01 71870 I212985 Fishman and Friedman, 1989

Silica , dissolved mg/L as SiO2 0.1 955 I270085 Fishman and Friedman, 1989

Residue, dissolved 180oC mg/L 10 70300 I175085 Fishman and Friedman, 1989

Nitrogen, Ammonia, dissolved mg/L as N 0.02 608 I252290 Fishman, 1993

Nitrogen, Nitrite, dissolved mg/L as N 0.01 613 I254090 Fishman, 1993

Nitrogen, Ammonia + Organic mg/L as N 0.1 623 I261091 Patton and Truitt, 1992

Nitrogen, Nitrite + Nitrate, 

dissolved

mg/L as N 0.05 631 I254590 Fishman, 1993

Phosphorus, total mg/L as P 0.05 665 I461091 Patton and Truitt, 1992

Phosphorus, dissolved mg/L as P 0.004 666 EPA 365.1 U.S.EPA, 1993

Phosphorus, Orthophosphate mg/L as P 0.01 671 I260190 Fishman, 1993

Arsenic, total* mg/L as As .001 1002 I406398 Brown, 1998

Arsenic, total, EPA mg/L as As .001 1002D EPA 200.9 U.S.EPA, 1993

Iron, total* mg/L as Fe .014 1045 I447197 Garberino and Struzeski, 1998

Iron, dissolved mg/L as Fe .01 1046 I147287 Fishman, 1993

Manganese, total* mg/L as Mn .003 1055 I447197 Garberino and Struzeski, 1998

Manganese, dissolved mg/L as Mn .003 1056 I147287 Fishman, 1993

* denotes method used for short-interval, time-series sample analysis.
20

The temperature of water pumped from wells 

during sampling ranged from 10.4oC to 15.5oC, with 

a mean of 12oC (approximately 54oF). The annual 

average daily air temperature for the Pontiac area is 

between 9 and 10oC (Soil Conservation Service, 

1982). Ground-water temperatures are usually 1 to 

2

oC higher than the mean annual air temperature 

(Todd, 1980). 

The concentration of dissolved solids in water 

can be approximated in the field by measuring the 

specific conductance of a sample (Hem, 1985). Fresh 

water is usually considered to be water containing 

less than 1,000 mg/L total dissolved solids (Drever, 

1988). The USEPA SMCL for dissolved solids is 500 

mg/L. On the basis of data collected in this study, the 

total dissolved solids concentration in ground water 

in Oakland County [in milligrams per liter (mg/L)] is 

typically about 58 percent of the specific conductance 

[measured in microsiemens/centimeter (μS/cm)]. 

Thus, the threshold between fresh and brackish water 

in Oakland County would be represented by a specific conductance of approximately 1,800 μS/cm, and 

the USEPA’s SMCL would be represented by a specific conductance of approximately 900 μS/cm. The 

specific conductance of ground water used for drinking in Oakland County ranged from 395 to 2,950 μS/

cm, with a mean value of 925 μS/cm.

Dissolved oxygen concentrations ranged between 

<0.1 and 7.8 mg/L, with a mean of 0.8 mg/L. In 

Michigan, the presence of DO in concentrations 

higher than 1.0 mg/L is typically associated with 

recently recharged, and usually shallow, ground 

water. The concentration of dissolved oxygen in the 

water, along with the oxidation-reduction potential 

(redox), controls the chemical and microbial reactions 

that can occur in ground water.

The pH of ground water in Oakland County varies between 6.5 and 7.6, with a mean of 7.1. Most 

ground water in the United States falls in the range of 

6.0 to 8.5 (Hem, 1985). The USEPA SMCL for pH 

specifies pH should fall between 6.5 and 8.0. 

The redox potential of Oakland County ground 

water ranged from -25mV to 876mV. The redox 

potential is not directly related to any health effects; 

rather, it is monitored as an indication of whether the 

subsurface environment is conducive to removing 

electrons from materials (high eH) or adding electrons to material (low eH). Higher eH values are 

often found in recently recharged waters, while lower 

eH values are found in older waters that have been 

exposed to more organic matter, carbonates, or bacteria (Drever, 1988). The redox potential of water is an 

important control on geochemical processes, and the 

determination of eH can indicate which ions are 

likely to be mobile in the system. The measurements 

included in appendix table 1B and elsewhere are 

approximate, based on results from an electrode measurement, rather than direct measurement of different 

species of the same ion.

The alkalinity of ground water in Oakland 

County ranged from 214 to 462 mg/L as CaCO3

-

. 

Alkalinity is a measure of the acid neutralizing ability 

of a sample, which can be the result of several ions in 

solution. In the pH ranges described above, the principal ion responsible for alkalinity is bicarbonate, 

HCO3

-

 (Hem, 1985). Like the redox potential, alkalinity is an indicator of the state of the geochemical 

system, and aids in the interpretation of other chemical constituents.

Inorganic Chemical Constituents

The USEPA has set drinking-water MCLs and 

SMCLs for several inorganic constituents analyzed in 

this study. These constituents, the USEPA threshold, 

and the type of threshold are shown in table 3 (U.S. 

Environmental Protection Agency, 1996). A complete list of inorganic chemistry analyses can be 

found in appendix table 1C. A summary of results for 

each inorganic constituent are shown in table 4.

Table 3. Inorganic constituents analyzed in this 

study with USEPA Drinking Water Standards

[mg/L, milligrams per liter; MCL, Maximum Contaminant Level; SMCL, Secondary Maximum Contaminant Level]

Constituent Limit Units Standard 

type

Nitrite 1 mg/L as N MCL

Nitrate 10 mg/L as N MCL

Chloride 250 mg/L as Cl SMCL

Sulfate 250 mg/L as SO4

-

SMCL

Flouride 4 mg/L as F SMCL

Arsenic .05 mg/L as As MCL

Iron .3 mg/L as Fe SMCL

Manganese .05 mg/L as Mn SMCL

Total Dissolved 

Solids

500 mg/L SMCL
21

None of the samples contained concentrations of sulfate 

or fluoride in excess of the SMCL. Samples from two wells 

exceeded the MCL for nitrate. Samples from more than half 

of the wells contained concentrations of iron in excess of the 

SMCL, and samples from nearly half of the wells contained 

concentrations of manganese in excess of the SMCL. Concentrations of arsenic in samples from five wells exceeded 

the MCL; although all of those wells were previously identified by MDEQ as having concentrations above the MCL. 

Samples from seven wells exceeded the SMCL for chloride. 

Samples from twelve wells exceeded the SMCL for total dissolved solids.

Elevated concentrations of iron, manganese, and arsenic 

are associated with ground water with lower redox potential 

at near-neutral pH (Hem, 1985; Kim, 1999; Korte and 

Fernando, 1991). This association can be observed in wells in 

Oakland County. However, nitrate and nitrite are readily 

reduced to nitrogen in low-redox environments. Appropriately, nitrate and nitrite were not present in any well with a 

concentration of arsenic, manganese, or iron in excess of the 

USEPA standard. Consumption of water with iron or manganese concentrations above the SMCL is not considered dangerous from a health perspective; however, both materials 

leave deposits in pipes and on fixtures, impart taste to beverages, and can discolor laundry (Shelton, 1997).

Sulfur is a common element in the Earth’s crust, and 

occurs as sulfate (SO4

2-) in waters with near-neutral pH and 

redox potential above –100 mV (Hem, 1985). Sulfate can be 

reduced under certain conditions to hydrogen sulfide, a compound with the smell of rotten eggs. In addition to leaving 

greenish deposits on plumbing fixtures, sulfate in concentrations above the SMCL can result in diarrhea (Shelton, 1997).

Fluoride is present in many natural waters in concentrations less than 1.0 mg/L. The MCL of 4.0 mg/L has been set 

to protect public health. Fluoride in excess of 4.0 mg/L can 

cause skeletal fluorosis, a serious bone disorder (Shelton, 

1997). Concentrations in excess of 2.0 mg/L can cause dental 

fluorosis, a staining and pitting of the teeth (Shelton, 1997)

The SMCL for dissolved solids is based on aesthetic concerns, and is primarily related to the life expectancy of 

domestic plumbing and appliances. The service life for a hot 

water heater is reduced by one year for every 200 mg/L of 

dissolved solids in water above the average 220 mg/L (Shelton, 1997).

Table 4: Summary statistics for selected inorganic constituents detected in water samples from selected 

wells in Oakland County, Michigan

[mg/L, milligrams per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; oC, degree Celsius]

Constituent Maximum Minimum Mean Median

Laboratory pH (Standa rd Units) 7.9 7.1 7.42 7.43

Nitrogen, Ammonia (mg/L as N) 1.4 <.02 .19 .14

Nitrogen, Nitrite (mg/L as N) .1 <.01 .01 <.01

Nitrogen, Ammonia + Organic (mg/L as N) 1.52 <.01 .22 .15

Nitrogen, Nitrate + Nitrite, dissolved (mg/L as N) 23.9 <.05 .90 <.05

Phosphorus, dissolved (mg/L as P) .5 <.004 .02 <.004

Phosphorus, ortho (mg/L as P) .5 <.01 .02 <.01

Calcium, dissolved (mg/L as Ca) 175 0.15 79.3 76.2

Magnesium, dissolved (mg/L as Mg) 57.7 0.02 29.0 27.5

Sodium, dissolved (mg/L as Na) 431 3.73 66.0 22.8

Potassium, dissolved (mg/L as K) 13 0.1 2.1 1.7

Chloride, dissolved (mg/L as Cl) 661 0.48 103. 23.3

Sulfate, dissolved (mg/L as SO 4

-

) 80.7 1.26 29.8 18.5

Flouride, dissolved (mg/L as F) 1.1 <.1 0.4 0.2

Silica, dissolved (mg/L as SiO 2) 23.0 9.25 14.7 14.3

Arsenic, total (mg/L as As) .176 <.001 .021 .003

Iron, dissolved (mg/L as Fe) 3.58 <.014 1.09 .927

Manganese, dissolved (mg/L as Mn) .330 <.003 .055 .032

Dissolved Residue of Evaporation, 180 oC (mg/L) 1620 228 529 387

Bromide, dissolv ed (mg/L as Br) 5.5 .01 .24 .06

Specific Conductance, (μS/cm at 25oC) 2950 408 913 640
22

Nutrients

Species of nitrogen and phosphorus are frequently referred to as nutrients, because they are essential to

plant life and are common in fertilizers, including manure, and in human waste. There are no health restrictions on consumption of phosphorus in drinking water, but the USEPA has set restrictions on nitrate 

(NO3

-

) and nitrite (NO2

-

). 

Sources

Nitrogen and phosphorus are essential to all known forms of life. Consequently, they can be found

throughout the environment in varying concentrations, even in rainwater. Typical nitrate concentrations in

the precipitation of southwestern Michigan are approximately 0.6 mg/L as N, and typical phosphorus concentrations are 0.05 mg/L (Cummings, 1978)

Human activities have done much to alter the distribution of nutrients in the environment. Application

of manure and chemical fertilizers to crops and lawns results in local abundance of nutrients, which is the

desired outcome. But over-application can result in local excesses of nutrients, which can reach ground

water. Septic tanks are designed to provide a means of containing and treating sewage, which typically contains elevated concentrations of nitrogen and phosphorus. But when environmental conditions, such as a

high water table, alter the operation of a septic tank, nitrogen and phosphorus can be released into the ground

water. The USEPA considers nitrate concentrations of 3 mg/L as N or higher to be the result of anthropogenic contamination (U.S. Environmental Protection Agency, 1996b). 

Occurrence

Concentrations of nitrate and nitrite in Oakland County drinking water ranged from below the reporting

limit (0.1 mg/L) to 23.9 mg/L as N, more than twice the MCL. Samples collected from two wells exceeded

the MCL, although samples from three more wells contained concentrations greater than 2 mg/L as N. While

not above the USEPA threshold for anthropogenic contamination, these concentrations are more than twice

the median, and more than three times the atmospheric loading. Nitrite concentrations were consistently less

than the MCL of 1.0 mg/L as N, ranging from 0.08 to less than the reporting limit of 0.01 mg/L as N. 

The CAER used 6,198 of the 12,942 nitrate analyses performed by MDEQ to generate the map of nitrate

occurrence in Oakland County (fig. 8). The majority of the discarded records were removed because of obvious errors in recording the address in the database. In the case of duplicate entries for a well, the highest concentration was retained. Each of the 900 survey sections in Oakland County was then assigned to one of four

groups; nitrate present above the MCL, nitrate present below the MCL, nitrate present below 3 mg/L-N, or

no observations. Approximately one percent (96) of the 7,814 unique wells identified by the CAER contained concentrations of nitrate greater than the MCL. A more detailed discussion of the mapping methods

employed and the comparison between USGS analytical results and MDEQ analytical results is included in

Appendix 2.

The map provides a summary of the nitrate data in the MDEQ database. Nitrate concentrations above 3

mg/L-N generally occur along a northeast-southwest axis, coincident with the region previously identified as

both the interlobate outwash plains and the region of with the most permeable soils (see figure 5). This pattern of nitrate contamination of ground water through high permeability surface sediments has been widely

documented in Michigan (Kittleson, 1987) and elsewhere (Madison and Brunett, 1985).

Nitrate concentrations in ground water change at spatial scales smaller than the square-mile mapping

unit used in these maps. The classification applied to any square-mile mapping unit does not necessarily

reflect the current status of all wells in that mapping unit. The data archived in the MDEQ database reflect

analyses of samples collected between 1983 and 1997, with varying sample collection, handling, and analysis techniques. For example, replicate samples collected in this study, and some samples collected by state

and county personnel, employed clean sampling techniques to minimize contamination. Samples in this

study (excluding the short-interval samples, discussed later), as well as samples collected by state and county

workers, were collected only after the well and plumbing system had been purged. Samples were returned to

the state laboratory the same day for analysis within the next two days. The majority of the samples in the

MDEQ database, however, were collected by homeowners and shipped by mail to the State laboratory for

analysis. Thus there is no standard control on sampling procedures, handling techniques, or the time elapsed

between sample collection and analysis. 
T. 5 N.

T. 4 N.

T. 3 N.

T. 2 N.

T. 1 N.

R. 7 E. R. 8 E. R. 9 E. R. 10 E. R. 11 E.

ROYAL 

OAK

SOUTHFIELD

FARMINGTON NOVI

LYON

BLOOMFIELD TROY

WEST 

BLOOMFIELD

COMMERCE MILFORD

AVON PONTIAC

WATERFORD WHITE

HIGHLAND LAKE

OAKLAND ORION

INDEPENDENCE SPRINGFIELD

ROSE

ADDISON OXFORD BRANDON HOLLY GROVELAND

Highest measured nitrate concentrations

(milligrams per liter as nitrogen)

No data

Less than 3 mg/L

Greater than or equal to 3 but less than 10 mg/L

Greater than or equal to 10 mg/L

Municipal boundaries

EXPLANATION

Figure 8. Nitrate distribution in Oakland County, Michigan. Map based on analyses performed at 

Michigan Department of Environmental Quality Drinking Water Laboratory.

0 5 10 Miles

0 5 10 15 Kilometers

Source: Section boundaries provided by Michigan 

Resource Information System.
24

Potential Health Effects

Nitrate has long been linked to methemoglobinemia in infants (Comly, 1945), commonly known as

“blue baby syndrome.” Methemoglobinemia occurs

when nitrite (NO2

-

), a reduced form of nitrate, interacts with red blood cells and impairs their ability to

carry oxygen (Mirvish, 1991). This impairment

results in anoxia (deficiency of oxygen in the blood)

and cyanosis (blue blood). In severe cases, blue-baby

syndrome can be fatal (U.S. Environmental Protection

Agency, 1996b). Susceptibility varies depending on

age, body mass, and diet, but fetuses and infants under

6 months are most at risk. This is because 1) infantile

hemoglobin is more susceptible to oxidation by nitrite

than adult hemoglobin, 2) infants consume more water 

per unit body weight than do adults, and 3) the activity

of the enzyme system that removes methemoglobin in

infants is lower in infants than in adults (Keeney and

Follett, 1991). For this reason, the USEPA has set

restrictions on nitrate (NO3

-

) and nitrite (NO2

-

) concentrations of 10.0 and 1.0 mg/L as nitrogen, respectively (U.S. Environmental Protection Agency,

1996a). Most laboratories report nitrate and nitrite

concentrations in terms of the weight of nitrogen (as

above). In terms of the mass of the whole molecule,

the MCLs are approximately 45 mg/L as NO3

-

 and 3.3

mg/L as NO2

-

.

USGS scientists use clean sampling techniques to collect water for analysis

from a residential well, Oakland County, Michigan.
25

Several authors (Keeney, 1986; Keeney and Follett, 1991; Moller and Forman, 1991; Crespi and Ramazotti, 1991) have accepted the correlation between

nitrate consumption and various forms of cancer. Nitrosamines, formed from ingested nitrite and amines,

which occur naturally in the digestive tract, also have

been identified as carcinogens in laboratory experiments (Crespi and Ramazotti, 1991). Because nitrate

and nitrite can be ingested from other sources, such as

food and wine, no evidence currently exists for evaluating potential carcinogenic effects of nitrate on

human populations (Crespi and Ramazotti, 1991).

Major Ions and Trace Metals

In addition to nutrients, water samples from the

wells in Oakland County were analyzed for more than

a dozen other characteristics. Summary statistics are

provided in table 4. The complete listing of these

results is included in appendix tables 1A to 1G. A

more detailed description of the sources, occurrence,

and health effects of chloride and arsenic has been

developed to assist county employees and citizens in

making decisions about drinking-water resources.

Collection of water samples for analysis, Oakland

County, Michigan.
26

Chloride

Chloride is found in virtually all ground water. Chloride can occur in ground water

naturally, but is also found throughout southeastern Michigan as the result of human

activities (Thomas, in press). The principal natural source of chloride in ground water

is seawater trapped within the rock matrix (Long and others, 1986). Several anthropogenic sources exist as well, including the salts used on roads for deicing and dust control, and water softeners. Chloride is a conservative ion in solution, and seldom

interacts in organic or inorganic reactions in the subsurface (Hem, 1985). As a result,

the evidence of anthropogenic additions of chloride may be present for many years.

Occurrence

Samples collected from 7 of the 37 wells exceeded the SMCL for chloride. Samples from every well contained a detectable concentration of chloride, ranging from

0.48 mg/L to 661 mg/L. The mean concentration was 104 mg/L and the median concentration was 23 mg/L. 

The CAER used 6,228 of the 12,960 chloride analyses performed by MDEQ to

generate the map of chloride occurrence in Oakland County (fig. 9). The majority of

the discarded records were removed because of obvious errors in the database. In the

case of duplicate entries for a well, the highest concentration was retained. Each of the

900 survey sections in Oakland County was then assigned to one of four groups; chloride present above the SMCL, chloride present below the SMCL, chloride present

below the MRL, or no observations. Approximately 5 percent (383) of the 7,809

unique wells identified by the CAER contained chloride in concentrations greater than

the SMCL of 250 mg/L. Of the unique wells identified from the database, 1,581 did

not have sufficient address location data to place them accurately on the map. A more

detailed discussion of the mapping methods employed and the comparison between

USGS analytical results and MDEQ analytical results is included in Appendix 2. 

This map provides a summary of the chloride data in the MDEQ database.

Because elevated chloride concentrations in ground water can come from both anthropogenic and natural sources, elevated chloride concentrations can be found throughout

the county. Chloride concentrations in ground water can change at spatial scales

smaller than the square-mile mapping unit used in these maps. The classification

applied to any square-mile mapping unit does not necessarily reflect the current status

of all wells in that mapping unit. 

The data archived in the MDEQ database reflect analyses on samples collected

between 1983 and 1997, with varying sample collection, handling, and analysis techniques. For example, replicate samples collected in this study, and some samples collected by state and county personnel, employed clean sampling techniques to minimize

contamination. Samples in this study (excluding the short-interval samples, discussed

later), as well as samples collected by state and county workers, were collected only

after the well and plumbing system had been purged. The majority of the samples in

the MDEQ database, however, were collected by homeowners and shipped by mail to

the State laboratory for analysis. Thus there is no standard control on sampling procedures, handling techniques, or the time elapsed between sample collection and analysis.

Potential Health Effects 

Hutchinson (1970) suggested that elevated chloride concentrations could have an

effect on persons with pre-existing cardiac (heart) or renal (kidney) problems. The

chloride SMCL of 250 mg/L is based on the aesthetic consideration of taste; water with

higher concentrations of chloride tastes ‘salty’ to most people. A greater concern

might be the presence of cations with chloride, such as sodium and potassium. Sodium

in drinking water can be a concern for those on low sodium diets because of cardiac,

circulatory, renal or other problems (Shelton, 1997).
R. 7 E. R. 8 E. R. 9 E. R. 10 E. R. 11 E.

T. 1 N.

T. 2 N.

T. 3 N.

T. 4 N.

T. 5 N.

ROYAL 

OAK

SOUTHFIELD

FARMINGTON NOVI

LYON

BLOOMFIELD TROY

WEST 

BLOOMFIELD

COMMERCE MILFORD

AVON PONTIAC WATERFORD WHITE

LAKE

HIGHLAND

OAKLAND ORION

INDEPENDENCE

SPRINGFIELD

ROSE

ADDISON OXFORD BRANDON HOLLY GROVELAND

Highest measured chloride concentrations 

(milligrams per liter)

No data

Less than 250 mg/L

Greater than or equal to 250 mg/L

Municipal boundary

EXPLANATION

Figure 9. Chloride distribution in Oakland County, Michigan. Map based on analyses performed by the Michigan 

Department of Environmental Quality Drinking Water Laboratory.

0 5 10 Miles

0 5 10 15 Kilometers

Source: Section boundaries provided by Michigan 

Resource Information System.
28

Arsenic

Arsenic is a common element in the Earth’s crust, and occurs naturally

throughout southeastern Michigan in several forms. In ground water, arsenic has

been observed to occur in two forms; the oxidized form, arsenate (As+5), or the

reduced form, arsenite (As+3). Kim (1999), working with the USGS Drinking

Water Initiative (DWI) project, has shown that most (65-94 percent) of the arsenic

in ground water in Oakland County is arsenite. Kim (1999) has also observed that

the presence of the bicarbonate ion (HCO3

-

) in solution can enhance the rate of

arsenic dissolution into ground water, although the species of arsenic released by

this process is arsenate. Arsenate is readily sorbed to metal oxides, such as iron

oxide, and rendered immobile (Korte and Fernando, 1996). For arsenic to be

released into solution from the mineral form, arsenian pyrite (Kolker and others,

1998), aquifer sediments must first be oxidized, then reduced. The hydrologic

mechanism facilitating this process has not yet been determined.

Occurrence

Low concentrations of arsenic are found throughout southeastern Michigan.

The largest concentration detected in Oakland County by this study was 0.175 

mg/L. Samples from five of the 38 wells exceeded the MCL, 0.05 mg/L, although

all had previously been noted to exceed the MCL based on results from the

MDEQ laboratory and were sampled to obtain additional supporting chemistry.

Of the other wells sampled, 9 contained arsenic in concentrations below the minimum reporting level of 0.001 mg/L. The remaining 24 wells all contained some

detectable concentration between 0.001 and 0.050 mg/L.

The CAER used 1,988 of the 3,509 arsenic analyses performed by MDEQ to

generate the map of arsenic occurrence (fig. 10) using procedures similar to those

described for nitrate and chloride. These maps are similar to those released previously in USGS Fact Sheet 135-98 (Aichele and others, 1998). Approximately one

percent (24) of the 2,373 unique wells identified by the CAER contained arsenic

at concentrations greater than the MCL of 0.05 mg/L. Of the unique wells identified from the database, 385 did not have sufficient address location data to place

them accurately on the map. A more detailed discussion of the mapping methods

employed and the comparison between USGS analytical results and MDEQ analytical results is included in Appendix 2.

The map provides a summary of the arsenic data in the MDEQ database.

Arsenic concentrations in ground water can change at spatial scales smaller than

the square-mile mapping unit used in these maps. The classification applied to any

square-mile mapping unit does not necessarily reflect the current status of all

wells in that mapping unit. 

The data archived in the MDEQ database reflect analyses on samples collected between 1983 and 1997, with varying sample collection, handling, and

analysis techniques. For example, replicate samples collected in this study, and

some samples collected by state and county personnel, employed clean sampling

techniques to minimize contamination. Samples in this study (excluding the

short-interval samples, discussed later), as well as samples collected by state and

county workers, were collected only after the well and plumbing system had been

purged. The majority of the samples in the MDEQ database, however, were collected by homeowners and shipped by mail to the State laboratory for analysis.

Thus there is no standard control on sampling procedures, handling techniques, or

the time elapsed between sample collection and analysis. 
R. 7 E. R. 8 E. R. 9 E. R. 10 E. R. 11 E.

T. 1 N.

T. 2 N.

T. 3 N.

T. 4 N.

T. 5 N.

ROYAL 

OAK

SOUTHFIELD

FARMINGTON NOVI

LYON

BLOOMFIELD TROY

WEST 

BLOOMFIELD

COMMERCE MILFORD

AVON PONTIAC WATERFORD WHITE

LAKE

HIGHLAND

OAKLAND ORION

INDEPENDENCE

SPRINGFIELD

ROSE

ADDISON OXFORD BRANDON HOLLY GROVELAND

EXPLANATION

Highest measured arsenic concentrations

(milligrams per liter)

No data

Greater than or equal to 0.05 mg/L

Municipal boundaries

Less than 0.05 mg/L

Figure 10. Arsenic distribution in Oakland County, Michigan. Map based on analyses performed by the Michigan 

Department of Environmental Quality Drinking Water Laboratory. The Maximum Contaminant Level (MCL) 

for arsenic, currently 0.05 mg/L, is being reviewed by the U.S. Environmental Protection Agency. 

0 5 10 Miles

0 5 10 15 Kilometers

Source: Section boundaries provided by Michigan 

Resource Information System.
30

Potential health effects 

The USEPA has set an MCL of 0.05 mg/L for 

arsenic in drinking water, although no distinction is 

made between the two arsenic species. In May, 

2000 the USEPA proposed revising the MCL to 

0.005 mg/L, and is accepting public comment on 

MCLs of 0.003 mg/L, 0.005 mg/L, 0.010 mg/L, and 

0.020 mg/L. A final decision is expected early in 

2001. 

Several authors have suggested that arsenite 

may be a more serious health concern than arsenate 

(Pontius and others,1994; Kosnett, 1997). The 

effects of chronic arsenic ingestion are based on the 

total daily dose and length of exposure, not the concentration specifically. The daily dosage from 

drinking water can be estimated based on the concentration in the water and the quantity of water 

consumed. For example: 

[As concentration] * Quantity of = Dose 

of water

0.050 mg/L * 2 L = 0.100 mg

0.025 mg/L * 2 L = 0.050 mg

This calculation is only an estimate of total 

daily arsenic ingestion, because there are other environmental sources of arsenic. Some of these 

sources include shellfish, meats, dust, soil, and 

some pigments. The U.S. Food and Drug Administration has estimated that US adults ingest about 

0.053 mg As/day from the diet, not including drinking water (Guo and others, 1998). Nearly half of 

this amount comes from fish and shellfish. Marine 

shellfish and cod typically contain arsenic concentrations between 10 and 40 mg/kg based on fresh 

weight (National Academy of Science, 1977). 

Freshwater fish, other marine fish, pork and beef 

typically contain less than 1 mg As/kg (National 

Academy of Science, 1977). 

Kosnett (1997) defines three classes of arsenic 

exposure, and outlines the symptoms and risks associated with each class. For an average adult, low 

exposure includes inorganic arsenic doses up to 0.5 

mg/day. Moderate exposure includes dose of 0.5 to 

1.5 mg/day, and high exposures are doses in excess 

of 1.5 mg/day. These exposure classes are based on 

the total mass of arsenic ingested from water 

(described above) and from food. Low doses seldom result in any noticeable symptoms of illness. 

Moderate exposures for prolonged periods (5 to 15 

years) may result in skin discoloration and lesions, 

anemia, peripheral neuropathy and peripheral vascular disease. In addition to the symptoms of moderate exposure, high doses may result in edema, 

more pronounced peripheral neuropathy including 

motor weakness, diminished reflexes, and muscle 

atrophy. High doses also may result in gastrointestinal disturbances such as nausea and diarrhea, as 

well as general fatigue and weight loss.

Arsenic has been listed as a Group A human 

carcinogen by the USEPA on the basis of inhalation 

and ingestion exposure. The carcinogenic effects of 

low-level arsenic ingestion in drinking water are 

widely disputed in the medical literature and are 

currently under review by the USEPA. Several case 

studies of groups exposed to arsenic occupationally 

or medicinally, such as Moselle wine growers 

(Luchtrath, 1983) and users of the Victorian health 

tonic ‘Fowler’s solution,’ an alkaline solution of 

potassium arsenate marketed in the US until 1980, 

have indicated increased risks of bladder cancers 

(Cuzick and others, 1992). Several studies in Taiwan (Tsuda and others, 1995; Pontius and others, 

1994) have observed increased risk of urinary tract 

cancers as a result of consuming water containing 

arsenic. No statistically significant relation was 

observed between arsenic concentration in drinking 

water and the occurrence of liver, kidney, bladder, 

or urinary tract cancer for persons consuming water 

containing less than 0.33 mg/L in Taiwan (Guo and 

others, 1998). 

Different populations may also have different 

processes to remove arsenic from the body. Most 

mammals remove arsenic from their bodies by 

incorporating the arsenic into organic compounds, a 

process known as methylation. These organic compounds are easier for the body to remove. Dr. 

Vasken Aposhian of the University of Arizona has 

determined that several South American mammals 

have developed a means of removing arsenic from 

the body other than methylation (Kaiser, 1998). 

Several native human populations in the Andes 

Mountains exhibit a similar trait (Kaiser, 1998). 

Despite drinking water with levels of arsenic more 

than twice the USEPA MCL, these populations do 

not exhibit any increased occurrence of cancer (Kaiser, 1998).

At this point, no comprehensive epidemiological study has been performed on a US population 

consuming arsenic in drinking water over an 
31

extended period of time. The best information 

available comes from studies in Taiwan and Bangladesh, whose populations differ sharply from 

United States populations in lifestyle, diet, and 

genetic inheritance.

Results of Time-Series Analyses

Analyses of well water samples collected by the 

Oakland County Health Division and homeowners 

as part of routine sampling have indicated changes 

in arsenic concentration of as much as 0.05 mg/L or 

more over periods of time ranging from days to 

years. This variation has raised concerns that 1) 

concentrations of arsenic and other dissolved constituents may be changing in the aquifer, or that 2) 

some samples may have been collected without an 

adequate well purge. An inadequate well purge 

would mean that drinking water (water drawn from 

a tap immediately) was being compared to ground 

water (water drawn after the plumbing system and 

well bore have been purged). As part of this study, 

ground-water samples were collected from selected 

wells to attempt to observe long-term variability in 

the aquifer, while drinking-water samples were collected to evaluate the potential to obtain varying 

results based on an inadequate purging of the well.

Very little change was observed in any characteristic between ground-water samples collected in 

June/July 1998 and those collected in December 

1998. 

All sites exhibited some chemical changes in 

the short-term drinking-water sampling (Appendix 

table 1E-1G). Total iron concentrations fluctuated 

with time in all wells, although the magnitude of the 

fluctuation was usually less than 10 percent of the 

concentration. OAK 35 exhibited a marked 

increase in iron and arsenic concentration over 

time. Iron concentrations increased from 216 to 

1500 μg/L over a span of 10 minutes. Arsenic concentrations increased from 0.001 mg/L to 0.01 

mg/L over a time span of four minutes. This sample was collected from a tap at an outbuilding that 

had not been used for more than two days. This 

point was sampled because, based on the chemistry 

data collected earlier, this well was expected to 

exhibit a short-term change. Improper purging of a 

well prior to sampling may result in lower concentrations of both arsenic and iron, particularly when 

the water has been standing in the pipes for a prolonged period. 

Results of Replicate Sample Analysis

The analytical results from the USGS NWQL 

and the MDEQ Drinking Water Laboratory for 

nitrate, chloride, and arsenic agree closely. Mean 

differences in concentration measurements for 

nitrate, chloride, and arsenic were 0.1, 6.8, and 

0.0008 mg/L, respectively. The standard deviation 

of the differences was 0.3, 9.6, and 0.003 mg/L for 

nitrate, chloride, and arsenic, respectively. Graphs 

showing the comparative analytical results over a 

range of concentrations are provided in 

Appendix 2. 

SUMMARY 

The quality of ground water in Oakland County 

is the result of a combination of natural and anthropogenic processes. Many wells produce highly 

reduced water with high concentrations of iron and 

manganese. All of the wells sampled during 1998 

contained chloride, although most contained concentrations below the U.S. Environmental Protection Agency (USEPA) Secondary Maximum 

Contaminant Level (SMCL). Twenty-nine of 

thirty-eight wells contained detectable concentrations of arsenic, although only five contained 

arsenic concentrations above the USEPA Maximum 

Contaminant Level (MCL). These five wells are 

best considered separately, because they were 

known from previous samplings to contain arsenic, 

and were sampled to provide additional chemical 

information. Only two wells contained nitrate in 

concentrations above the MCL, although three 

additional wells contained concentrations several 

times higher than would be expected to be found in 

precipitation. 

Seasonal variations in water-quality were not 

observed in any of the five wells resampled in 

December 1998. Some short-term variations during 

the purging of the wells were observed in all wells. 

All wells exhibited variation in iron concentration; 

three of five exhibited fluctuations of approximately 10 percent, while 2 of the five exhibited 

increasing trends. One well exhibited an increasing 

trend in arsenic concentration, coincident with an 

increasing trend in iron concentration. Thus, while 

in many cases analytical results may not be affected 

by the length of time a well is purged, in at least one 

of the five subject wells purge time would have 

influenced the resulting arsenic concentration. 
32

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34

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Michigan, 98 p.
APPENDIX 1: Water-quality data collected by the USGS in Oakland County, Michigan 

The following several pages contain the results of water-quality sample collection activities conducted by the USGS in cooperation with the Oakland County Health Division. Included is a key 

for cross-referencing station names (e.g. OAK 1) to USGS site identification numbers, a table of 

field-analyzed characteristics for each sample site, a table with the results of analyses for selected 

inorganic constituents, a table containing the results of seasonal analyses for selected inorganic 

constituents, and a series of tables containing the results of short-interval time-series sampling for 

arsenic, manganese and iron. 

35 
Table 1A. Index of station names with U.S. 

Geological Survey (USGS) station 

identification numbers 

Station name USGS Station ID 

OAK 1 425032083230101 

OAK 2 424835083250601 

OAK 3 425050083310901 

OAK 4 425219083264301 

OAK 7 424351083365501 

OAK 8 424303083142101 

OAK 9 425055083374901 

OAK 10 425154083370001 

OAK 11 425221083374101 

OAK 12 425131083363001 

OAK 14 424308083245701 

OAK 15 424315083182801 

OAK 16 424323083250501 

OAK 17 425218083375001 

OAK 19 425033083165701 

OAK 20 423307083290201 

OAK 21 424315083183901 

OAK 22 423105083173201 

OAK 23 423108083173801 

OAK 24 423036083182701 

OAK 24A 425157083083001 

OAK 25 425042083083101 

OAK 26 425046083083601 

OAK 29 423334083293601 

OAK 30 423343083292101 

OAK 31 424505083205901 

OAK 32 423847083265601 

OAK 33 423817083365501 

OAK 34 424144083074701 

OAK 35 424519083081101 

OAK 36 422850083230101 

OAK 37 423600083262301 

OAK 38 424048083243201 

OAK 39 424504083324901 

OAK 40 424319083315701 

OAK 41 423855083292201 

OAK 42 425051083310701 

OAK 43 425056083310101 

 

36 
Table 1B. Field measurements of water-quality characteristics for ground water samples from selected wells in 

Michigan [μS/cm, microsiemens per centimeter at 25 degrees Celsius; mV, millivolts; mg/L, milligrams per liter; oC, degrees CelsiusStation name 

Sample 

date 

Sample 

 time 

Depth, 

(feet) 

Field Specific Conductance (μS/cm) 

Oxidationreduction Potential  (mV) 

Oxygen, Dissolved (mg/L) 

pH, Field (Standard Units) 

Temperature (oC) 

OAK 1 6/3/98 930 474 35 0.1 7.3 11.3 OAK 2 6/3/98 1225 711 35 <.1 7.2 11.5 OAK 4 6/4/98 905 482 40 <.1 7.4 11.5 OAK 3 6/4/98 1225 86 503 81 .1 7.4 12.3 OAK 7 6/4/98 1430 695 180 <.1 7.1 11.4 OAK 8 6/9/98 930 1560 65 .1 6.9 11.1 OAK 9 6/9/98 1130 520 55 .1 7.3 11.6 OAK 10 6/9/98 1300 300 581 88 .1 7.2 13.1 OAK 11 6/25/98 1630 -- -- -- -- -- OAK 12 6/26/98 1146 300 600 100 .1 7.0 11.4 OAK 14 6/25/98 1350 142 570 40 <.1 7.1 12.2 OAK 15 6/25/98 1000 753 26 <.1 7.0 13.5 OAK 16 6/25/98 1220 161 556 175 <.1 7.3 13.5 OAK 17 6/25/98 1520 634 44 <.1 7.0 12.7 OAK 19 6/26/98 920 2950 288 7.8 6.5 12.3 OAK 21 6/25/98 915 1344 244 3.1 6.6 12.1 OAK 22 6/30/98 900 60 1910 66 .1 6.6 13.0 OAK 23 6/30/98 1000 1325 92 .1 6.7 12.0 OAK 24 6/30/98 1100 75 1439 51 <.1 -- 11.8 OAK 24A 7/1/98 900 2420 94 .1 7.0 11.4 OAK 25 7/1/98 1030 681 70 .1 7.4 12.2 OAK 26 7/1/98 1130 54 680 321 4.9 7.2 11.3 OAK 29 7/7/98 900 1540 65 1.5 7.1 12.0 OAK 30 7/7/98 1010 1209 43 <.1 7.3 13.0 OAK 31 7/7/98 1215 73 1174 233 5.4 6.9 10.4 OAK 32 7/7/98 1400 1307 46 .1 7.3 12.1 OAK 33 7/7/98 1530 1155 169 .1 7.1 12.2 OAK 34 7/8/98 930 395 -25 .1 7.6 11.6 

37 
Table 1B. Field measurements of water-quality characteristics for ground water samples from selected wells in 

Michigan – Continued [μS/cm, microsiemens per centimeter at 25 degrees Celsius; mV, millivolts; mg/L, milligrams per liter; oC, degrees CelsiusStation  name 

Sample 

date 

Sample 

time 

Depth Field Specific 

Conductance (μS/cm) 

Oxidation – Reduction Potential (mV) 

Oxygen, Dissolved (mg/L) 

pH, Field (Standard Units) 

Temperature (oC) 

OAK 35 7/8/98 1055 601 19 <0.1 7.2 10.9 OAK 36 7/8/98 1310 605 33 .1 7.1 11.3 OAK 20 7/8/98 1430 491 35 .1 7.0 12.3 OAK 37 7/20/98 930 967 208 <.1 6.9 11.7 OAK 38 7/20/98 1120 795 876 7.0 7.2 15.5 OAK 39 7/20/98 1330 636 61 <.1 7.0 11.5 OAK 40 7/20/98 1445 519 64 .1 7.0 11.1 OAK 41 11/23/98 2000 577 33 .1 7.5 11.3 OAK 42 12/16/98 1115 492 195 .2 7.2 10.8 

38 OAK 43 12/16/98 1230 462 230 .1 7.4 11.1 
Table 1C. Results of analyses for selected inorganic chemical constituents in groundwater samples from selected wells in Oakland County, Michigan 

[mg/L, milligrams per liter; μg/L, micrograms per liter; E, estimate; --, No data] 

Station 

name 

Station ID Sample 

date 

Sample 

time 

Depth, 

feet 

 Nitrogen, 

Ammonia 

mg/L as N 

Nitrogen, Nitrite 

mg/L as N 

OAK 1 425032083230101 06/03/98 930 0.25 <0.01 

OAK 2 424835083250601 06/03/98 1225 .34 .02 

OAK 4 425219083264301 06/04/98 905 .30 .02 

OAK 3 425050083310901 06/04/98 1225 86 .11 .02 

OAK 7 424351083365501 06/04/98 1430 .02 .08 

OAK 8 424303083142101 06/09/98 930 .11 .01 

OAK 9 425055083374901 06/09/98 1130 .20 .01 

OAK 10 425154083370001 06/09/98 1300 300 .21 .01 

OAK 11 425221083374101 06/25/98 1630 -- -- 

OAK 12 425131083363001 06/26/98 1146 300 .16 <.01 

OAK 14 424308083245701 06/25/98 1350 142 .12 <.01 

OAK 15 424315083182801 06/25/98 1000 .20 <.01 

OAK 16 424323083250501 06/25/98 1220 161 <.02 <.01 

OAK 17 425218083375001 06/25/98 1520 .21 <.01 

OAK 19 425033083165701 06/26/98 920 .02 .01 

OAK 21 424315083183901 06/25/98 900 .02 .01 

OAK 22 423105083173201 06/30/98 900 60 .16 <.01 

OAK 23 423108083173801 06/30/98 1000 .07 <.01 

OAK 24 423036083182701 06/30/98 1100 75 .07 <.01 

OAK 24A 425157083083001 07/01/98 900 .05 <.01 

OAK 25 425042083083101 07/01/98 1030 .11 <.01 

OAK 26 425046083083601 07/01/98 1130 54 .04 <.01 

OAK 29 423334083293601 07/07/98 900 .24 <.01 

OAK 30 423343083292101 07/07/98 1010 .24 <.01 

OAK 31 424505083205901 07/07/98 1215 73 .04 <.01 

OAK 32 423847083265601 07/07/98 1400 .04 <.01 

OAK 33 423817083365501 07/07/98 1530 .05 .03 

OAK 34 424144083074701 07/08/98 930 .31 <.01 

OAK 35 424519083081101 07/08/98 1055 .29 <.01 

OAK 36 422850083230101 07/08/98 1310 .32 <.01 

OAK 20 423307083290201 07/08/98 1430 .56 <.01 

OAK 37 423600083262301 07/20/98 930 .40 <.01 

OAK 38 424048083243201 07/20/98 1120 <.02 <.01 

OAK 39 424504083324901 07/20/98 1330 .05 <.01 

OAK 40 424319083315701 07/20/98 1445 .02 <.01 

OAK 41 423855083292201 11/23/98 2000 1.40 <.01 

OAK 42 425051083310701 12/16/98 1115 .26 .03 

OAK 43 425056083310101 12/16/98 1230 .05 .02 

39 
Table 1C. Results of analyses for selected inorganic chemical constituents in groundwater samples from selected wells in Oakland County, Michigan – Continued 

[mg/L, milligrams per liter; μg/L, micrograms per liter; E, estimate; --, No data] 

Station 

name 

Nitrogen, Ammonia + 

Organic mg/L as N 

Nitrite + Nitrate, 

Dissolved 

mg/L as N 

Phosphorus, 

Dissolved 

mg/L as P 

Phosphorus, Ortho 

mg/L as P 

Calcium, 

Dissolved 

mg/L as Ca 

OAK 1 .24 <.05 <.01 <.01 49.1 

OAK 2 .27 .06 <.01 .02 67.7 

OAK 4 .27 .06 <.01 .01 48.5 

OAK 3 .12 .05 <.01 .01 63.9 

OAK 7 <.1 .92 <.01 .02 81.7 

OAK 8 <.1 <.05 <.01 <.01 149. 

OAK 9 .16 <.05 <.01 .01 57.0 

OAK 10 .15 <.05 <.01 <.01 63.4 

OAK 11 -- -- -- -- -- 

OAK 12 .18 <.05 <.01 <.01 66.1 

OAK 14 <.1 <.05 <.01 <.01 69.3 

OAK 15 .33 <.05 <.01 <.01 93.5 

OAK 16 <.1 <.05 .03 .05 0.2 

OAK 17 .31 <.05 <.01 <.01 79.1 

OAK 19 .15 23.86 <.01 <.01 84.0 

OAK 21 .11 13.97 <.01 <.01 145. 

OAK 22 .23 <.05 <.01 <.01 131. 

OAK 23 <.1 <.05 <.01 <.01 115. 

OAK 24 .13 <.05 <.01 <.01 65.2 

OAK 24A <.1 <.05 <.01 <.01 175. 

OAK 25 .14 <.05 <.01 <.01 79.8 

OAK 26 <.1 2.34 <.01 <.01 89.4 

OAK 29 .31 <.05 <.01 <.01 114. 

OAK 30 .40 <.05 <.01 <.01 87.2 

OAK 31 .12 2.56 <.01 <.01 130. 

OAK 32 .11 <.05 .01 <.01 101. 

OAK 33 <.10 2.12 <.01 <.01 100. 

OAK 34 .36 <.05 .03 .04 30.8 

OAK 35 .31 <.05 <.01 .02 59.9 

OAK 36 .37 <.05 <.01 <.01 69.7 

OAK 20 .68 <.05 <.01 <.01 69.8 

OAK 37 .49 .20 <.01 .02 88.5 

OAK 38 <.10 .16 .54 .52 83.6 

OAK 39 <.10 <.05 <.01 .01 86.7 

OAK 40 <.10 <.05 <.01 .01 73.3 

OAK 41 1.52 .05 .02 .10 67.3 

OAK 42 .41 <.05 <.01 .01 65.0 

OAK 43 <.10 <.05 .02 .04 0.1 

40 
Table 1C. Results of analyses for selected inorganic chemical constituents in groundwater samples from selected wells in Oakland County, Michigan – Continued 

[mg/L, milligrams per liter; μg/L, micrograms per liter; E, estimate; --, No data] 

Station 

name 

Magnesium, 

Dissolved 

mg/L as Mg 

Sodium, 

Dissolved 

mg/L as Na 

Potassium, 

Dissolved 

mg/L as K 

Chloride, 

Dissolved 

mg/L as Cl 

Sulfate, Dissolved 

mg/L as SO4

OAK 1 24.9 14.8 1.3 3.6 12.0 

OAK 2 32.8 26.6 1.6 53.5 18.9 

OAK 4 24.2 17.7 1.8 6.8 2.0 

OAK 3 23.7 6.2 1.1 1.2 14.1 

OAK 7 27.9 19.1 1.5 26.2 42.0 

OAK 8 48.1 85.2 3.9 253. 80.7 

OAK 9 26.7 16.5 1.4 0.5 11.3 

OAK 10 32.6 14.0 1.9 0.5 9.8 

OAK 11 -- -- -- -- -- 

OAK 12 36.6 13.0 1.6 .58 11.3 

OAK 14 26.8 14.4 1.0 13.0 15.2 

OAK 15 27.5 18.7 1.8 68.2 48.1 

OAK 16 .02 139. .1 6.1 13.7 

OAK 17 33.1 7.2 1.8 6.9 10.4 

OAK 19 57.7 431. 13.0 661. 58.8 

OAK 21 51.8 64.5 1.9 110. 68.7 

OAK 22 37.6 198. 2.5 367. 60.2 

OAK 23 37.8 90.8 2.7 194. 65.2 

OAK 24 45.8 145. 4.2 249. 68.6 

OAK 24A 51.5 204. 1.9 444. 57.7 

OAK 25 30.7 9.2 1.3 10.4 34.4 

OAK 26 28.5 3.7 .8 4.1 31.0 

OAK 29 29.3 156. 2.9 289. 62.5 

OAK 30 22.6 124. 4.1 226. 14.9 

OAK 31 40.2 54.2 1.9 140. 17.3 

OAK 32 26.9 116. 2.4 253 53.3 

OAK 33 27.4 101. 2.4 156. 51.9 

OAK 34 18.6 26.8 1.3 3.5 1.3 

OAK 35 25.6 26.6 1.3 30.5 10.7 

OAK 36 26.1 18.2 1.5 29.2 1.7 

OAK 20 18.3 3.8 .8 .9 6.4 

OAK 37 20.1 86.7 1.9 132. 33.6 

OAK 38 30.0 37.3 1.8 66.0 34.3 

OAK 39 29.8 6.8 1.0 3.5 46.2 

OAK 40 22.9 4.0 1.1 7.7 30.7 

OAK 41 -- 11.4 1.4 20.3 18.2 

OAK 42 23.1 10.0 1.8 2.6 8.2 

OAK 43 0.1 120. .4 1.2 15.2 

41 
Table 1C. Results of analyses for selected inorganic chemical constituents in groundwater samples from selected wells in Oakland County, Michigan – Continued 

[mg/L, milligrams per liter; μg/L, micrograms per liter; E, estimate; --, No data] 

Station 

name 

Silica, Dissolved 

mg/L as SiO2

Arsenic, Total 

μg/L as As 

Iron, Dissolved 

μg/L as Fe 

Manganese, 

Dissolved 

μg/L as Mn 

Residue, Dissolved, 

180oC mg/L 

OAK 1 16.1 40 742 9 278 

OAK 2 14.5 26 2116 38 411 

OAK 4 13.5 46 581 38 278 

OAK 3 16.7 27 459 23 294 

OAK 7 9.25 <1 89 330 410 

OAK 8 14.6 8 2815 65 862 

OAK 9 17.6 39 746 17 307 

OAK 10 19.3 53 577 13 343 

OAK 11 -- 68 -- -- -- 

OAK 12 19.4 56 499 18 350 

OAK 14 18.3 24 1100 26 330 

OAK 15 14.5 2 2299 51 428 

OAK 16 17.8 11 <10 < 4 350 

OAK 17 19.6 39 1853 15 367 

OAK 19 13.8 <1 <30 < 12 1620 

OAK 21 15.0 <1 13 < 4 794 

OAK 22 13.1 -- 2123 93 1050 

OAK 23 11.5 1 1206 37 752 

OAK 24 11.7 2 2228 76 794 

OAK 24A 12.9 2 1506 158 1282 

OAK 25 17.2 19 1152 31 375 

OAK 26 14.6 <1 <10 < 4 387 

OAK 29 13.1 <1 1978 49 894 

OAK 30 12.2 <1 1317 95 688 

OAK 31 11.5 <1 27 <4 686 

OAK 32 11.0 1 2028 94 750 

OAK 33 9.85 <1 24 77 684 

OAK 34 14.2 <1 549 9 228 

OAK 35 16.7 12 1246 21 331 

OAK 36 17.2 4 1329 14 348 

OAK 20 16.9 3 2361 51 301 

OAK 37 10.3 <1 68 285 561 

OAK 38 16.6 3 <10 <4 482 

OAK 39 14.0 3 1534 32 388 

OAK 40 11.0 <1 755 36 316 

OAK 41 23.0 176 3575 -- -- 

OAK 42 10.4 34 206 114 299 

OAK 43 13.9 57 E 6 <3 304 

42 
Table 1C. Results of analyses for selected inorganic chemical constituents in groundwater samples from selected wells in Oakland County, Michigan – Continued 

[mg/L, milligrams per liter; μg/L, micrograms per liter; E, estimate; --, No data] 

Station 

name 

Bromide, 

Dissolved 

mg/L as Br 

 Acid Neutralizing Capacity, 

pH 4.5 mg/L as CaCO3

OAK 1 0.07 252 

OAK 2 .08 286 

OAK 4 .03 263 

OAK 3 .03 268 

OAK 7 .05 296 

OAK 8 .09 344 

OAK 9 .03 280 

OAK 10 .02 319 

OAK 11 -- -- 

OAK 12 .05 332 

OAK 14 .06 281 

OAK 15 .17 247 

OAK 16 .04 284 

OAK 17 .05 336 

OAK 19 5.51 325 

OAK 21 .19 445 

OAK 22 .24 353 

OAK 23 .28 308 

OAK 24 .24 275 

OAK 24A .64 367 

OAK 25 .03 295 

OAK 26 .03 290 

OAK 29 .12 294 

OAK 30 .07 263 

OAK 31 .06 413 

OAK 32 .06 226 

OAK 33 .13 325 

OAK 34 .03 215 

OAK 35 .07 276 

OAK 36 .09 287 

OAK 20 .03 267 

OAK 37 .09 279 

OAK 38 .04 288 

OAK 39 .06 308 

OAK 40 .05 246 

OAK 41 .08 -- 

OAK 42 .04 272 

OAK 43 .01 247 

43 
Table 1D. Seasonal comparison of selected water-quality parameters for samples from selected wells in Oakland 

Michigan [mg/L, milligrams per liter; μg/L, micrograms per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; 0C, degStation name OAK 3 OAK 4 OAK 9 OAK 12 Station number 425050083310901 425219083264301 425055083374901 425131083363001 Sample date 6/4/98 12/16/98 6/4/98 12/15/98 6/9/98 12/3/98 6/26/98 12/3/98 7Sample time 1225 950 905 1545 1130 1500 1146 1700 1pH, Laboratory (Standard Units) 

7.3 7.6 7.5 7.7 7.6 7.6 7.4 7.4 

Nitrogen, Ammonia (mg/L as N) 

.11 .11 .30 .25 .20 .18 .16 .18 

Nitrogen, Nitrite (mg/L as N) 

.02 .02 .02 .02 .01 <.01 <.01 <.01 

Nitrogen, Ammonia + Organic (mg/L as N) 

.12 <.1 .27 .31 .16 .28 .18 .24 

Nitrite + Nitrate, Dissolved (mg/L as N) 

.05 <.05 .06 <.05 <.05 <.05 <.05 <.05 

Phosphorus, Dissolved (mg/L as P) 

<.01 <.05 <.01 <.05 <.01 <.05 <.01 <.05 

Phosphorus, Ortho (mg/L as P) 

.01 .01 .01 .01 .01 .01 <.01 <.01 

Calcium, Dissolved (mg/L as Ca) 

63.9 63.1 48.5 50.5 57.0 57.4 66.1 66.4 

Magnesium, Dissolved (mg/L as Mg) 

23.7 22.6 24.2 24.3 26.7 24.6 36.6 33.6 

Sodium, Dissolved (mg/L as Na) 

6.2 5.9 17.7 15.9 16.5 15.0 13.0 12.0 

44 
Table 1D. Seasonal comparison of selected water-quality parameters for samples from selected well in Oakland C

Michigan--Continued 

[mg/L, milligrams per liter; μg/L, micrograms per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; 0C, degreStation name OAK 3 OAK 4 OAK 9 OAK 12 Station number 425050083310901 425219083264301 425055083374901 425131083363001 Sample date 6/4/98 12/16/98 6/4/98 12/15/98 6/9/98 12/3/98 6/26/98 12/3/98 Sample time 1225 950 905 1545 1130 1500 1146 1700 Flouride, Dissolved  (mg/L as F) 

.3 .3 .8 .8 .7 .6 .9 .9 

Silica, Dissolved (mg/L as SiO2) 

16.7 16.2 13.5 14.0 17.6 17.7 19.4 20.1 

Arsenic, Total  (μg/L as As) 

27 27 46 48 39 38 56 58 

Iron, Dissolved (μg/L as Fe) 

459 577 581 974 746 745 499 504 

Manganese Dissolved  (μg/L as Fe) 

23 20 38 42 17 17 18 15 

Residue, Dissolved, 180oC 

 (mg/L) 

294 294 278 270 307 305 350 290 

Bromide, Dissolved  (mg/L as Br) 

.03 .12 .03 .15 .03 .05 .05 .04 

Specific Conductance  (μS/cm) 

497 509 493 484 513 525 611 609 

Acid Neutralizing Capacity, pH 4.5 (mg/L as CaCO3) 

268 234 263 255 280 278 332 330 

45 
Table 1E. Total arsenic concentrations in drinking water at selected 

ground-water sampling sites in Oakland County, Michigan 

[All concentrations are in micrograms per liter; --, No data. Time is measured 

in seconds from the time water began to flow] 

 

Station name Oak 41 Oak 9 Oak 12 Oak 35 Oak 4 

Sample date 11/23/98 12/3/98 12/3/98 12/15/98 12/15/98 

Seconds 0 177 17 50 1 47 

30 -- 40 -- -- -- 

60 180 38 52 2 47 

90 180 -- -- -- -- 

120 177 36 50 3 48 

150 181 36 -- -- -- 

180 173 37 51 2 47 

210 -- 37 -- -- -- 

240 194 37 48 10 49 

270 188 -- -- -- -- 

300 180 36 58 10 51 

360 172 37 56 11 51 

420 177 37 55 11 53 

480 174 39 53 12 50 

540 -- 38 52 11 50 

600 173 38 63 11 49 

660 -- -- -- 12 49 

720 179 41 59 11 48 

780 -- -- -- 11 51 

840 171 39 56 11 48 

900 -- 38 -- 12 48 

960 181 40 60 12 49 

1020 -- -- 58 12 50 

1080 176 40 58 12 51 

1140 -- -- -- 12 50 

1200 176 -- 58 11 -- 

1260 -- -- -- -- -- 

1320 -- -- -- 12 -- 

1380 -- -- -- 12 -- 

1440 -- -- -- 12 -- 

46 
Table 1F. Total manganese concentrations in drinking water at selected ground water 

sampling sites in Oakland County, Michigan 

[All concentrations are in micrograms per liter; -- No data. Time is measured in seconds 

from the time water began to flow]

 

Station name Oak 41 Oak 9 Oak 12 Oak 35 Oak 4 

Sample date 11/23/98 12/3/98 12/3/98 12/15/98 12/15/98 

Seconds 0 59 <10. 15 22 42 

30 -- 15 -- -- -- 

60 56 17 15 23 45 

90 56 -- -- -- -- 

120 57 17 15 23 44 

150 56 16 -- -- -- 

180 60 16 14 23 44 

210 -- 17 -- -- -- 

240 58 16 14 23 44 

270 59 -- -- -- -- 

300 59 17 14 24 42 

360 60 16 14 23 43 

420 60 17 14 24 43 

480 61 16 14 24 44 

540 -- 16 14 24 43 

600 62 16 13 24 44 

660 -- -- -- 24 43 

720 65 16 13 25 44 

780 -- -- -- 25 44 

840 62 16 14 23 44 

900 -- -- -- 23 44 

960 62 16 12 23 44 

1020 -- -- -- 24 44 

1080 63 16 13 24 45 

1140 -- -- -- 25 44 

1200 65 -- 13 24 -- 

1260 -- -- -- -- -- 

1320 -- -- -- 24 -- 

1380 -- -- -- 24 -- 

1440 -- -- -- 23 -- 

 

47 
Table 1G. Total iron concentrations in drinking water at selected ground water 

sampling sites in Oakland County, Michigan 

[All concentrations are in micrograms per liter; -- No data. Time is measured in seconds 

from the time water began to flow]

 

Station name Oak 41 Oak 9 Oak 12 Oak 35 Oak 4 

Sample date 11/23/98 12/3/98 12/3/98 12/15/98 12/15/98 

Seconds 0 4040 38 398 216 1013 

30 -- 854 -- -- -- 

60 3790 685 413 171 1280 

90 3710 -- -- -- -- 

120 3740 668 388 374 1191 

150 3880 676 -- -- -- 

180 4095 674 392 432 1260 

210 -- 668 -- -- -- 

240 4050 674 416 1345 1193 

270 4130 -- -- -- -- 

300 4190 671 525 1325 906 

360 4090 670 501 1525 930 

420 4110 676 465 1455 949 

480 3995 696 432 1455 1083 

540 -- 687 440 1415 1097 

600 4155 686 553 1500 1114 

660 -- -- -- 1440 973 

720 4290 758 491 1370 1005 

780 -- -- -- 1390 985 

840 4350 698 462 1365 1001 

900 -- -- -- 1325 1138 

960 4235 692 507 1355 1122 

1020 -- -- -- 1520 1116 

1080 4115 724 502 1550 1137 

1140 -- -- -- 1500 1132 

1200 4265 -- 489 1480 -- 

1260 -- -- -- -- -- 

1320 -- -- -- 1570 -- 

1380 -- -- -- 1470 -- 

1440 -- -- -- 1480 -- 

 

48 
APPENDIX 2 – Results of replicate sample analyses by U.S. Geological Survey National 

Water Quality Laboratory and the Michigan Department of Environmental Quality Drinking 

Water Laboratory

Mapping Methods 

The The maps showing the distribution of nitrate, chloride, and arsenic in Oakland County 

(figs. 8, 9, and 10, this report) were produced in collaboration with the Center for Applied 

Environmental Research at the University of Michigan – Flint (CAER). Results of water-quality 

analyses by the MDEQ Drinking Water Laboratory were checked by manual and automated 

methods for accuracy and completeness by CAER. Results were then sorted to identify unique 

wells. If two or more samples were analyzed from any one well, the highest value was retained. 

These unique wells were then assigned a geographic coordinate location using the Geocoding 

process in ArcView 3.1 (Environmental Systems Research Institute, 1998). In each case, some 

fraction of the unique wells identified did not contain sufficient address information to obtain a 

unique position. 

These point files were then spatially joined to an Oakland County section map provided by 

Michigan Department of Natural Resources. Once each point had been assigned to a section, the 

highest concentration value for the section was determined from the database, and the section 

classified. For points exceeding the Maximum Contaminant Level (MCL) or the Secondary 

Maximum Contaminant Level (SMCL), a buffer of one-quarter mile was placed around the well 

head. Any section that entered the buffer was reclassified into the MCL or SMCL exceedance 

class. This classification superceded any previous classification. 

Geocoding, development of mapping methods, and production of maps for USGS Fact 

Sheet 135-98 (Aichele and others, 1998) was performed by the CAER. Production of the maps 

seen in this report used the same data bases and methods, but maps were modified to meet USGS 

publication guidelines.

Replicate Sample Analysis 

Twenty-six replicate samples were collected for analysis by the MDEQ Drinking Water 

Laboratory. Samples were collected from sites with a wide variety of concentration levels for 

each constituent, based on the results of previous water-quality analyses. The purpose of this 

activity was to provide a basis for comparison between USGS analytical results for arsenic, 

nitrate and chloride and the results obtained by the MDEQ. Neither laboratory was informed that 

a replicate sample was being analyzed elsewhere. Collection procedures were identical, and 

samples were handled in accordance with each laboratory’s specified procedures, including 

limitations on holding times in the case arsenic and nitrate. Graphs of the results of these 

analyses are presented in the figures A2.1, A2.2, and A2.3. 

The mean difference between the USGS results and the MDEQ results was 0.1, 6.8 and 

0.0008 mg/ L for nitrate, chloride, and arsenic, respectively. The standard deviation of the 

differences was 0.3, 9.6, and 0.003 for nitrate, chloride, and arsenic, respectively. 

49 
 

0 5 10 15 20 25

USGS

0

5

10

15

20

25

MDEQ

0 100 200 300 400 500 600 700

USGS

0

200

400

600

MDEQ

0 10 20 30 40 50 60 70

USGS

0

20

40

60

MDEQ

Figure 2A. Nitrate 

concentrations as determined 

by the Michigan Department 

of Environmental Quality 

Drinking Water Laboratory 

(MDEQ) and the U.S. 

Geological Survey National 

Water Quality Laboratory 

(USGS). Concentrations in 

milligrams per liter as 

nitrogen.

Figure 2B. Chloride 

concentrations as determined 

by the Michigan Department 

of Environmental Quality 

Drinking Water Laboratory 

(MDEQ) and the U.S. 

Geological Survey National 

Water Quality Laboratory 

(USGS). Concentrations in 

milligrams per liter.

Figure 2C. Arsenic 

concentrations as 

determined by the 

Michigan Department of 

environmental Quality 

Drinking Water Laboratory 

(MDEQ) and the U.S. 

Geological Survey 

National Water Quality 

Laboratory (USGS). 

Concentrations in 

micrograms per liter.

50 
Table 2A. Analytical results of nitrate and nitrite analyses from the U.S. Geological 

Survey National Water Quality Laboratory and the Michigan Department of 

Environmental Quality Drinking Water Laboratory 

[USGS, U.S.Geological Survey National Water Quality Laboratory; MDEQ, Michigan 

Department of Environmental Quality Drinking Water Laboratory; mg/L, milligrams 

per liter; --, no data] 

Station ID USGS 

Nitrite 

(mg/L as N) 

USGS 

Nitrite + 

Nitrate 

(mg/L as N) 

MDEQ 

Nitrite 

(mg/L as N) 

MDEQ 

Nitrate 

(mg/L as N) 

423307083290201 <0.01 0.0 <0.05 <0.4 

424144083074701 < .01 .0 <.05 <.4 

425221083374101 -- -- <.05 <.4 

425131083363001 < .01 .0 <.05 <.4 

425033083165701 .01 23.9 <.05 23 

425157083083001 < .01 .0 <.05 <.4 

423105083173201 < .01 .0 <.05 <.4 

423334083293601 < .01 .0 <.05 <.4 

423847083265601 < .01 .0 <.05 <.4 

423036083182701 < .01 .0 <.05 <.4 

423343083292101 < .01 .0 <.05 <.4 

423108083173801 < .01 .0 <.05 <.4 

423817083365501 .03 2.12 <.05 2 

424505083205901 < .01 2.56 <.05 2.4 

423600083262301 < .01 .20 <.05 <.4 

424315083183901 .01 14.00 <.05 13 

424048083243201 < .01 .16 <.05 <.4 

424519083081101 < .01 .0 <.05 <.4 

422850083230101 < .01 .0 <.05 <.4 

424308083245701 < .01 .0 <.05 <.4 

425042083083101 < .01 .0 <.05 <.4 

424319083315701 < .01 .0 <.05 <.4 

425218083375001 < .01 .0 <.05 <.4 

424323083250501 < .01 .0 <.05 <.4 

424504083324901 < .01 .0 <.05 <.4 

425046083083601 < .01 2.34 <.05 2.2 

51 
Table 2B. Analytical results of chloride analyses from the U.S. Geological Survey 

National Water Quality Laboratory and the Michigan Department of Environmental 

Quality Drinking Water Laboratory 

[USGS, U.S. Geological Survey National Water Quality Laboratory; MDEQ, Michigan 

Department of Environmental Quality Drinking Water Laboratory; mg/L, milligrams per liter; 

--, no data] 

Station ID MDEQ Chloride 

(mg/L) 

USGS Chloride 

(mg/L) 

422850083230101 30 29.2 

423036083182701 256 248.5 

423108083173801 199 194.4 

423307083290201 <4 0.9 

423334083293601 314 289.2 

423343083292101 252 225.6 

423600083262301 132 131.6 

423817083365501 171 156.2 

423847083265601 284 252.5 

424048083243201 68 66.0 

424144083074701 0 3.5 

424308083245701 14 13.0 

424315083182801 -- 68.2 

424315083183901 118 109.8 

424319083315701 9 7.7 

424323083250501 7 6.1 

424504083324901 4 3.5 

424505083205901 151 139.5 

424519083081101 30 30.5 

425033083165701 670 661.4 

425042083083101 10 10.4 

425046083083601 4 4.1 

425131083363001 <4 0.6 

425157083083001 469 444.2 

425218083375001 8 6.9 

425221083374101 <4 -- 

52 
Table 2C. Analytical results of arsenic analyses from the U.S. Geological Survey 

National Water Quality Laboratory and the Michigan Department of Environmental 

Quality Drinking Water Laboratory 

[USGS, U.S.Geological Survey National Water Quality Laboratory; MDEQ, Michigan 

Department of Environmental Quality Drinking Water Laboratory; mg/L, milligrams 

per liter] 

Station ID USGS Total Arsenic 

 (mg/L as As) 

MDEQ Total Arsenic 

 (mg/L as As) 

423307083290201 0.003 0.0014 

424144083074701 <.001 <.0001 

425221083374101 .068 .0698 

425131083363001 .056 .0612 

425033083165701 <.001 .0075 

425157083083001 .002 .0025 

423334083293601 <.001 <.0001 

423847083265601 .001 .0016 

423036083182701 .002 .0023 

423343083292101 <.001 .0012 

423108083173801 .001 .0014 

423817083365501 <.001 <.0001 

424505083205901 <.001 <.0001 

423600083262301 <.001 <.0001 

424315083183901 <.001 <.0001 

424048083243201 .003 .0051 

424519083081101 .012 .0018 

422850083230101 .004 .0050 

424308083245701 .024 .0261 

425042083083101 .019 .0214 

424319083315701 .000 .0015 

425218083375001 .039 .0443 

424323083250501 .011 .0110 

424504083324901 .003 .0044 

425046083083601 <.001 <.0001 

424315083182801 .002 .0017 

53