fig2

fig 4

Prepared in cooperation with the Geauga County Planning Commission and Board of Commissioners

Groundwater Quality in Geauga County, Ohio—

Status, Including Detection Frequency of Methane in 

Water Wells, 2009, and Changes During 1978–2009

Chester Twp. Huntsburg Twp.

1400

690

40

15

45

15

50

380

60

2 30

120

WEST

A

FEET

A ́

EAST

FEET

1,400

1,300

1,200

1,100

1,000

900

800

700

600

500

1,400

1,300

1,200

1,100

1,000

900

800

700

600

500

VERTICAL SCALE GREATLY EXAGGERATED

DATUM IS NGVD 29

0 1 2 3 4 5 6 MILES

0 1 2 3 4 5 6 KILOMETERS

East Branch Chagrin River

Chagrin River

West Branch Cuyahoga River 

East Branch Cuyahoga River

0

5,000

10,000

15,000

20,000

1950s 1960s 1970s 1980s 1990s 2000s

25,000

Number of people added each decade

Base from U.S. Geological Survey

1:24,000 data

0 5 MILES

0 5 KILOMETERS

Land-cover data from U.S Geological Survey

National Land Cover Database 1992–2001

Retrofit Land Cover Change Product

(Fry and others, 2009) 

81°20'

41°30'

41°40'

81°10'

Cleveland

Scientific Investigations Report 2015–5032

U.S. Department of the Interior

U.S. Geological Survey
Front cover: Collection of figures from the report, including map of Geauga County, a cross section of the area, and sample graph of county 

population growth. For more details, see figures 2, 4 and 6.
Groundwater Quality in Geauga County, 

Ohio—Status, Including Detection 

Frequency of Methane in Water Wells, 

2009, and Changes During 1978–2009 

By Martha L. Jagucki, Stephanie P. Kula, and Brian E. Mailot

Prepared in cooperation with the Geauga County Planning Commission and 

Board of Commissioners

Scientific Investigations Report 2015–5032

U.S. Department of the Interior

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

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2015

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

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

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

visit http://www.usgs.gov/pubprod/.

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

U.S. Government.

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

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

Suggested Suggested citation:

Jagucki, M.L., Kula, S.P., and Mailot, B.M., 2015, Groundwater quality in Geauga County, Ohio—Status, including 

detection frequency of methane in water wells, 2009, and changes during 1978–2009: U.S. Geological Survey Scientific Investigations Report 2015–5032, 116 p., 5 app., http://dx.doi.org/10.3133/sir20155032.

ISSN 2328-031X (print)

ISSN 2328-0328 (online)

ISBN 978-1-4113-3914-9
iii

Contents

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

Introduction.....................................................................................................................................................2

Purpose and Scope ..............................................................................................................................3

Description of Study Area ............................................................................................................................3

Aquifers and Directions of Groundwater Flow ................................................................................3

Annual Precipitation.............................................................................................................................5

Land Use and Population ....................................................................................................................5

Water Use ..............................................................................................................................................9

Groundwater Levels ..........................................................................................................................10

Water Levels, 1978–1994...........................................................................................................10

Water Levels, 1996–2012...........................................................................................................10

Septic Systems and Licensed Land Application of Septage and Biosolids .............................12

Oil and Gas Drilling ............................................................................................................................12

Road Deicing........................................................................................................................................15

Water-Quality Issues Identified in Previous Investigations .................................................................15

Groundwater Affected by Localized Chemical and Gas Releases.............................................16

Methods of Study.........................................................................................................................................18

Well Selection, Water-Quality Sampling Procedures, and Laboratory Analysis .....................18

Public-Supply Well Data From the Ohio Environmental Protection Agency.............................21

Evaluation of the Effect of Land Cover and Population Characteristics on Water Quality.....21

Statistical Analysis to Evaluate Changes Over Time ....................................................................25

Evaluation of Oxidation-Reduction Conditions in the Subsurface..............................................26

Groundwater Quality ...................................................................................................................................26

Status in 2009 ......................................................................................................................................26

Comparison to Health-Based Benchmarks...........................................................................26

Arsenic ...............................................................................................................................30

Total and Fecal Coliform Bacteria..................................................................................30

Trace Metals......................................................................................................................30

Sodium ...............................................................................................................................31

Manganese........................................................................................................................31

Pesticides ..........................................................................................................................31

Volatile Organic Compounds...........................................................................................32

Comparison to Aesthetically Based Standards....................................................................32

Comparison of Findings to State and National Studies of Water Quality ........................33

Occurrence of Methane in Groundwater.......................................................................................36

Changes in Water Quality Over Time...............................................................................................38

Changes in Water Quality, 1986 to 2009 and 1999 to 2009, in Resampled Wells..............38

Changes During 1978–2009 in Concentrations of Frequently Detected Constituents ...42

Changes Over Time Of Constituents With Infrequent Detections .....................................45

Factors Affecting Contaminant Occurrence and Constituent Concentrations in 

Groundwater..........................................................................................................................49

Human Activities at Land Surface ..........................................................................................50
iv

Sources of Salinity............................................................................................................50

Other Factors That Can Influence Concentrations of Total Coliform 

Bacteria, Nitrate, and Sulfate ..........................................................................54

Activities Affecting Pesticide and VOC Concentrations ...........................................55

Activities Affecting Bromide and Organic Carbon Concentrations .........................56

Naturally Occurring Geochemical Processes in the Subsurface .....................................57

Evolution of Groundwater Along a Flow Path ..............................................................58

Ion-Exchange Reactions With Aquifer Sediments......................................................58

Oxidation-Reduction Reactions......................................................................................62

Stratigraphic Traps That May Control Areas of Methane Accumulation.........................68

Considerations for Future Work ................................................................................................................69

Summary and Conclusions.........................................................................................................................71

References Cited..........................................................................................................................................75

Appendix 1: Variation in Water Levels in Selected Long-Term Network Wells Relative to 

Variation in Annual Precipitation.................................................................................................82

Appendix 2: Quality Assurance/Quality Control......................................................................................93

Appendix 3. Land Cover and Population Upgradient of Each Well....................................................103

Appendix 4. Water-Quality Data..............................................................................................................104

Appendix 5. Oxidation-Reduction Classification of Samples .............................................................114

Figures

1. Maps showing groundwater levels and direction of flow in Geauga County, Ohio, 

September 6–9, 1994, in the Pottsville Formation and glacial deposits and in the 

Berea Sandstone ..........................................................................................................................4

2. Cross section showing generalized geologic section of Geauga County, Ohio.................5

3. Graph showing variation in annual precipitation in Northeast Ohio relative to timing

of water-quality sampling by the U.S. Geological Survey in Geauga County 

Ohio, 1978–2009.............................................................................................................................6

4. Graph showing number of people added each decade in Geauga County, Ohio, 

1950–2009 .......................................................................................................................................6

5. Map showing population density in Geauga County, Ohio, 2000, based on the 2000 

Census Blocks and the 2001 National Land Cover Database................................................7

6. Map showing land-cover change in Geauga County, Ohio, 1992 to 2001 ...........................8

7. Map and graphs showing long-term groundwater-level network in Geauga County, 

2009, and comparison of water levels in selected wells, 1980-2012, to variations in 

annual precipitation, 1977–2012 ...............................................................................................11

8. Map showing authorized biosolids application sites in Geauga County, 2009, and 

registered septage-spreading sites, 2011 ..............................................................................13

9. Map showing oil and gas wells and active Class II injection wells in Geauga County, 

2008 ...............................................................................................................................................14

10. Graph showing road-salt use in Geauga County, Ohio, 1991–2011 ....................................15

11. Map showing approximate location of sites in Geauga County, Ohio, where human 

effects on groundwater from industrial or commercial point sources have been 

documented.................................................................................................................................17

12. Map showing data source and geologic unit of wells used to evaluate suitability of 

water for drinking, Geauga County, Ohio................................................................................19
v

13. Diagrams showing method used to determine area for categorizing upgradient land 

use and population .....................................................................................................................24

14. Graphs showing comparison of detection frequencies or exceedance frequencies of 

health-based and aesthetically based benchmarks in groundwater at the county, 

state, and national level.............................................................................................................34

15. Graphs showing properties and constituents with a statistically significant change in 

concentration from 1986 to 1999 or 1999 to 2009 in resampled wells, Geauga County, 

Ohio ...............................................................................................................................................40

16. Box plot showing changes in sulfate concentrations, 1978–2009, in samples from the 

Cuyahoga Group, Geauga County, Ohio..................................................................................44

17. Box plots showing changes of selected constituent ratios and concentrations in all 

wells sampled by the U.S. Geological Survey in Geauga County, Ohio, 1978–2009 ........45

18. Graphs showing comparison of total coliform concentrations in 1999 and 2009 in 

samples from wells with at least one detection, Geauga County, Ohio ............................46

19. Graphs showing detection frequency of nitrate in Geauga County, Ohio, 1978–2009, 

when censored to a common reporting level of 0.18 milligram per liter...........................47

20. Graph showing detection frequency of orthophosphate in Geauga County, Ohio, by 

aquifer, 1986–2009, when censored to a common reporting level of 0.01 milligram 

per liter .........................................................................................................................................47

21. Graph showing orthophosphate concentrations, 1986–2009, for wells in Geauga 

County, Ohio, producing water with a concentration greater than or equal to 

0.01 milligram per liter in one or more years..........................................................................48

22. Graph showing detection frequency of total sulfide by year, Geauga County, Ohio, 

1986–2009 .....................................................................................................................................48

23. Graph showing sulfide concentrations in Geauga County, Ohio, 1999 and 2009, for 

wells producing water with a sulfide concentration greater than or equal to 

0.01 milligram per liter in one or both years ...........................................................................49

24. Graphs showing relation of selected constituent concentrations to well depth for 

samples collected by the U.S. Geological Survey, Geauga County, Ohio, 

1978–2009 ....................................................................................................................................51

25. Graph showing relation of chloride concentration to depth to water for samples 

collected by the U.S. Geological Survey in Geauga County, Ohio, 1986–2009 .................52

26. Graph showing concentration of total coliform bacteria as a function of turbidity for 

samples collected by the U.S. Geological Survey from domestic wells, Geauga 

County, Ohio, 2009.......................................................................................................................54

27. Graphs showing relation of nitrate concentration to environmental characteristics for 

samples collected by the U.S. Geological Survey in Geauga County, Ohio, 2009............55

28. Graph showing population and percent developed land use upgradient of publicsupply well fields considered in this report and domestic wells sampled in 2009, 

Geauga County, Ohio..................................................................................................................56

29. Graph showing concentration of bromide as a function of depth to water in wells 

sampled by the U.S. Geological Survey, Geauga County, Ohio, 1986–2009 ......................57

30. Graph showing changes from 1999 to 2009 in bromide concentrations as a function 

of distance of well from road for wells sampled by the U.S. Geological Survey, 

Geauga County, Ohio..................................................................................................................57

31. Graphs showing relation of selected constituent concentrations to elevation of well 

bottom for samples collected by the U.S. Geological Survey, Geauga County, Ohio, 

1978–2009 .....................................................................................................................................59
vi

32. Map showing redox condition of wells tapping the Pottsville Formation, 1978–2009, 

relative to groundwater flow and locations of potential sources of nitrate near 

land surface. ...............................................................................................................................65

33. Box plot showing thickness of clay and shale overlying the Pottsville Formation in 

Geauga County, Ohio, by groundwater redox condition at sampled well locations, 

1978–2009 .....................................................................................................................................66

34. Map showing locations of wells tapping a strongly reducing groundwater 

environment relative to locations of wells with samples that have exceeded the 

health-based benchmarks for arsenic or manganese, for wells sampled by the 

U.S. Geological Survey, Geauga County, Ohio, 1978–2009...................................................67

35 Map showing elevation of top of the Berea Sandstone in Geauga County, Ohio, and 

location of methane detections, June 2009............................................................................70

1–1. Graphs showing relation of water levels in selected long-term network wells, 

1978–2012, to variation in annual precipitation......................................................................84

1–2. Graph showing relation of measured difference in water level between 1986 and 

1994 to departure of water level from annual precipitation trendline, 1986 or earlier....83

2–1. Graphs showing changes in percent recovery over time for selected constituents 

analyzed by the National Water Quality Laboratory.............................................................99

4–1. Map showing locations of wells sampled by the U.S. Geological Survey in Geauga 

County, Ohio, 1978–2009...........................................................................................................105

Tables

1. Percentages of land-cover types and impervious area, by township, Geauga 

County, Ohio, 2001.........................................................................................................................9

 2. Water levels in well GE-147, Middlefield Township, Geauga County, Ohio, 

1975–2009 .....................................................................................................................................10

3. Characteristics of wells sampled by the U.S. Geological Survey in Geauga County, 

Ohio, June 2009, and constituents for which water samples were analyzed ..................20

4. Physical characteristics of public-supply well fields considered in this report and 

analyses available, Geauga County, Ohio, 2000–2010 ..........................................................22

5. Exceedances of health-based benchmarks and aesthetically based standards in 

water quality of 16 domestic wells (2009) and 7 public-supply well fields (2000–2010) 

in Geauga County, Ohio..............................................................................................................28

6. Dissolved gas concentrations in selected groundwater samples from domestic 

wells, Geauga County, Ohio, June 2009 ..................................................................................37

7. Studies of dissolved methane in residential water wells ....................................................37

8. Statistical test results for differences in constituent concentrations between 

years in samples from wells that were able to be resampled by the U.S. Geological 

Survey in Geauga County, Ohio, from 1986 to1999 or 1999 to 2009.....................................39

9. Correlation of chemical properties or constituents of wells sampled by U.S. 

Geological Survey, 1978–2009, to year sampled...................................................................43

10. Possible sources near land surface of selected constituents in groundwater...............52

11. Lines of evidence investigated to distinguish between sources of salinity in 

groundwater of Geauga County, Ohio.....................................................................................53

12. Redox conditions in groundwater samples collected by the U.S. Geological Survey 

during 1978–2009 in Geauga County, Ohio, threshold criteria, and associated 

contaminants...............................................................................................................................63
vii

1–1. Comparison of water-level difference, 1986–1994, to approximate magnitude of 

water-level departure from annual precipitation trendline for wells with historical 

data in Geauga County, Ohio.....................................................................................................82

2–1. Chemical characteristics of selected quality-control samples collected in Geauga 

County, Ohio, June and July 1999 and June 2009..................................................................94

2–2. Expected median constituent concentrations in paired wells in 2009 based on 

laboratory percent recovery ratios 2009:1999......................................................................101

2–3. Comparison of median values of dissolved oxygen, pH, and specific conductance 

in 2009 to expected variation in 1999 median values caused by measurement 

stabilization for 16 paired wells..............................................................................................102

3–1. Land-cover types, population, number of acres permitted for biosolids spreading, 

and number of producing oil and gas wells upgradient of 16 domestic wells 

sampled in 2009, and 7 selected water-supply well fields in Geauga County, Ohio......103

4–1. Selected chemical characteristics of water samples collected by the 

U.S. Geological Survey in Geauga County, Ohio, 1978–2009 .............................................104

4–2. Pesticides analyzed for in groundwater samples from 16 domestic wells in Geauga 

County, June 2009 .....................................................................................................................106

4–3. Volatile organic compounds and semivolatile organic compounds analyzed for in 

groundwater samples in Geauga County, Ohio, 1995–2009...............................................108

5–1. Redox environment classification for domestic wells sampled by U.S. 

Geological Survey in Geauga County, Ohio, 1978–2009......................................................114
viii

Conversion Factors

Multiply By To obtain

Length

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2

)

acre 0.004047 square kilometer (km2

)

square mile (mi2

) 2.590 square kilometer (km2) 

Volume

milliliter (mL) 0.03382 ounce, fluid (fl. oz)

gallon (gal) 3.785 liter (L) 

gallon (gal) 0.003785 cubic meter (m3

) 

million gallons (Mgal) 3,785 cubic meter (m3

)

Flow rate

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

gallon per day (gal/d) 0.003785 cubic meter per day (m3

/d)

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

/s)

inch per year (in/yr) 25.4 millimeter per year (mm/yr)

Mass

milligram (mg) 0.00003527 ounce, avoirdupois (oz)

microgram (μg) 1,000 milligram (mg)

Radioactivity

picocurie per liter (pCi/L) 0.31 tritium units

picocurie per liter (pCi/L) 0.037 becquerel per liter (Bq/L) 

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows: 

°F = (1.8×°C)+32

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows: 

°C = (°F-32)/1.8

Vertical coordinate information is generally referenced to the National Geodetic Vertical Datum 

of 1929 (NGVD 29) for wells first sampled 1978 to 1986 and to the North American Vertical 

Datum of 1988 (NAVD 88) for wells sampled only in 1999 and 2009.

Horizontal coordinate information is generally referenced to the North American Datum of 1927 

(NAD 27) for wells first sampled 1978 to 1986. For wells sampled only in 1999 and 2009, horizontal coordinates are generally referenced to the North American Datum of 1983 (NAD 83).
ix

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

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 25 °C).

Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) or 

micrograms per liter (μg/L).

Other abbreviations used in this report:

DCA Dichloroethane

DWA Drinking Water Advisory

HA-C 10−6 Cancer Risk Concentration

HA-L Lifetime Health Advisory

MCL Maximum Contaminant Level

NTU Nephelometric turbidity unit

OAC Ohio Administrative Code

Ohio EPA Ohio Environmental Protection Agency

ODNR–MRM Ohio Department of Natural Resources, Division of Mineral Resources Management

PCE Perchloroethene

SMCL Secondary Maximum Contaminant Level

TCE Trichloroethene

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

VOC Volatile Organic Compound
x

Acknowledgments

The authors would like to thank the 16 homeowners who have allowed USGS personnel to collect water samples from their wells—some of them for the past three decades. Additionally, the 

authors appreciate the valuable assistance during the data-gathering process of Linda Slattery 

at Ohio Environmental Protection Agency, Division of Drinking and Ground Waters; Rick Simmers 

and Tom Tomastik at Ohio Department of Natural Resources–Mineral Resources Management; 

David Dietrich, Geauga County Planning Director; the Geauga County Engineer’s office; and Bob 

Weisdack, Geauga County Health Commissioner. 
Groundwater Quality in Geauga County, Ohio—

Status, Including Detection Frequency of Methane in 

Water Wells, 2009, and Changes During 1978–2009 

By Martha L. Jagucki, Stephanie P. Kula, and Brian E. Mailot 

Abstract

Domestic wells that are not safeguarded by regular waterquality testing provide drinking water for 79 percent of the 

residents of Geauga County, in northeastern Ohio. Since 1978, 

the U.S. Geological Survey (USGS) has worked cooperatively 

with the Board of Commissioners and Geauga County Planning Commission to monitor the quality of groundwater in 

four commonly used aquifers in county—the glacial deposits, 

the Pottsville Formation, the Cuyahoga Group, and the Berea 

Sandstone. A 33-percent growth in population from 1980 to 

2009 increased the potential for humans to influence groundwater resources by withdrawing more groundwater, disposing of more human waste near the land surface, treating an 

expanded network of township roads with deicing salt, and 

likely using more solvents, pesticides, and other chemicals on 

the land surface than were used in preceding decades. 

To describe the status of groundwater quality in 2009 and 

its suitability for drinking, USGS personnel collected samples 

of water prior to treatment from 16 wells (mostly domestic) 

during June 9–19. The samples were analyzed for 92 properties and constituents, 41 of which had human-health benchmarks to which analytical results could be compared to evaluate suitability for drinking. Four of these benchmarks were 

exceeded at the following frequencies: arsenic (2 of 16 wells, 

12.5 percent), total coliform bacteria (2 of 16 wells, 12.5 

percent), fecal coliform bacteria (1 of 14 wells, 7 percent), 

and sodium (6 of 16 wells, 38 percent). No domestic wells 

sampled in 2009 exceeded the health-based benchmark of 300 

micrograms per liter (μg/L) for manganese, although 5 of 65 

wells (8 percent) sampled since 1978 have. Analyses from 

domestic wells were augmented with water-quality data from 

seven public-supply well fields that were obtained from the 

Ohio Environmental Protection Agency. These public-supply 

data were typically collected between 2000 and 2010 and represent water samples that were collected prior to treatment or 

that were treated by a method that does not effectively remove 

the constituents of interest. Similar to the domestic-well data, 

these data indicated that some samples from public-supply 

wells have also exceeded health-based benchmarks for arsenic 

and sodium, along with occasional exceedances of healthbased benchmarks for cadmium and lead. Concentrations of 

nitrate, pesticides, and volatile organic compounds in groundwater samples from domestic and (or) public-supply wells 

were either considerably less than the human-health benchmarks for these constituents or were not detected. 

Water-quality data collected in 2009 were also compared 

to aesthetically based benchmarks developed by the U.S. 

Environmental Protection Agency, called Secondary 

Maximum Contaminant Levels (SMCLs). Iron and manganese 

most frequently exceeded SMCLs (in samples from 10 of 

16 domestic wells and in untreated water from 3 of 4 publicsupply well fields).

To evaluate the frequency of methane detection in water 

wells in the county, the USGS sampled 16 wells across the 

county and screened the samples for combustible gas within 

the headspace (the air above the water in a closed container). 

Water from three (19 percent) of the wells contained 

detectable combustible gas (0.10 to 0.40 percent by volume). 

All three detections were from wells tapping the Cuyahoga 

Group or the Berea Sandstone, and all detections were less 

than the lower explosive limit of 5 percent by volume—the 

concentration at which methane in air can be flammable 

if an ignition source is present. Analyses of dissolved gas 

composition in water from these three wells showed methane 

concentrations ranging from 0.007 to 1.8 milligrams per liter 

(mg/L). 

The primary effect of human activities on groundwater 

quality found during this study is the input of salinity, or 

chloride, near land surface. On the basis of ratios of chloride 

to bromide, the main sources of chloride are road salt and 

septic leachate rather than oil-field brines (either spilled at land 

surface or sprayed on roads for dust control). The correlation 

of chloride concentration to distance of well from road for 31 

wells in the county sampled by the U.S. Geological Survey in 

1999 suggests that road salt is the dominant source of chloride. 

The majority of constituents exceeding health-based and 

aesthetically based benchmarks in groundwater were those that 

are naturally present in aquifer rocks and sediments rather than 

constituents introduced by human activities. Concentrations 
2 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

of such natural contaminants are controlled by geochemical 

processes in the subsurface, particularly by oxidationreduction (redox) reactions. The categorization of redox 

conditions based on the water quality of 116 samples collected 

from 65 wells in Geauga County during 1978 through 2009 

indicates that most groundwater samples were strongly 

reducing (60 percent) or oxic (18 percent). Oxic waters were 

found only in the Pottsville Formation and Berea Sandstone 

and were generally associated with nitrate at concentrations 

of 0.38 to 6.0 mg/L. Strongly reducing waters occurred in 

all four commonly used aquifers and were associated with 

the following naturally occurring contaminants: (1) arsenic 

and manganese at concentrations exceeding the health-based 

benchmarks (10 μg/L and 300 μg/L, respectively) in some 

samples, (2) iron and manganese at concentrations exceeding 

the aesthetically based standards (300 μg/L and 50 μg/L, 

respectively) in most samples, and (3) total sulfides (consisting 

of hydrogen sulfide gas with its characteristic rotten-egg 

odor and [or] iron sulfide minerals that appear as finely 

disseminated particulates in water). 

Because of the association of redox conditions with 

specific contaminants, attempts were made to further 

document spatially where oxic and strongly reducing 

conditions occur so that contaminant occurrence can be 

better anticipated by planners and well owners. Within 

the Pottsville Formation, wells tapping strongly reducing 

groundwater tended to have a greater thickness of overlying 

low-permeability (recharge-inhibiting) material such as clay 

and shale than other wells tapping oxic or nitrate-reducing 

groundwater. In the Berea Sandstone, oxic conditions were 

found at well locations where either depth to groundwater 

was shallow (less than 45 feet [ft] below land surface) or the 

measured water level was within the open interval (uncased 

portion) of the well, whereas strongly reducing groundwater 

was found at well locations where depths to water were greater 

than 60 ft below land surface and measured water levels were 

15 ft or more above the open interval of the well.

To evaluate whether constituent concentrations 

consistently increased or decreased over time, the strength of 

the association between sampling year (time) and constituent 

concentration was statistically evaluated for 116 water-quality 

samples collected by the USGS in 1978, 1980, 1986, 1999, 

and 2009 from a total of 65 wells across the county (generally 

domestic wells or wells serving small businesses or churches). 

Results indicate that many of the constituents that have been 

analyzed for decades exhibited no consistent temporal trends 

at a statistically significant level (p-value less than 0.05); 

fluctuations in concentrations of these constituents represent 

natural variation in groundwater quality. Dissolved oxygen, 

calcium, and sulfate concentrations and chloride:bromide 

ratios increased over time in one or more aquifers, while pH 

and concentrations of bromide and dissolved organic carbon 

decreased over time. Detections of total coliform bacteria and 

nitrate did not become more frequent from 1986 to 2009, even 

though potential sources of these constituents, such as number 

of septic systems (linked to population) and percent developed 

land in the county, increased during this period. 

Introduction

Groundwater in Geauga County, Ohio, is an important 

resource because it is the primary drinking-water supply 

for over 98 percent of residents in the county (Kenney and 

others, 2009). For the past three decades, the U.S. Geological 

Survey (USGS) has worked in cooperation with the Board 

of Commissioners to evaluate the potential effects of human 

development and changing land use on the quantity and 

quality of groundwater resources in the four primary aquifers 

used in the county—the glacial deposits, the Pottsville 

Formation, the Cuyahoga Group, and the Berea Sandstone. 

The initial investigation of groundwater quantity in the 

county began in 1978, when the USGS measured water levels 

in 77 wells and produced a generalized water-level map of 

the uppermost bedrock aquifers (Nichols, 1980). To better 

understand the groundwater flow system and to predict future 

water-level changes on the basis of forecasted population 

growth and water use, the USGS measured water levels 

in 125 wells in 1986 and developed a numerical computer 

model (Eberts and others, 1990). Because the computer model 

had predicted that an increase in population might cause 

water-level declines in some areas, water levels were again 

measured in 1994—this time in 219 wells. Detailed maps 

showing directions of flow in the four primary aquifers were 

constructed, and changes in water level from 1986 to 1994 

were evaluated in 88 wells that were able to be remeasured 

(Jagucki and Lesney, 1995). Water levels in 70 percent of the 

wells had declined between 1986 and 1994, although it was 

not clear whether this was a temporary fluctuation caused by 

less precipitation in 1994 than in 1986 or was a lasting decline 

caused by greater groundwater withdrawals in 1994 than in 

1986 due to population growth. To distinguish between these 

two factors and to establish a framework for long-term waterlevel monitoring, a network of 31 wells was established in 

1996 in which depth to groundwater is regularly measured 

(ongoing as of the date of writing). Water-level variations 

in each well are routinely compared to variations in annual 

precipitation. 

Groundwater quality in the four primary aquifers used 

in the county has also been assessed as part of past USGS 

studies. Water-quality samples were collected primarily 

from domestic wells or from drinking-water wells at small 

businesses, churches, rest stops, or parks in 1978 (Nichols, 

1980; 14 samples), 1980 (U.S. Geological Survey, 1981; 24 

samples), 1986 (Eberts and others, 1990; 42 samples), and 

1999 (Jagucki and Darner, 2001; 31 samples). Statistical 

differences in water quality between aquifers were described 

by Jagucki and Darner (2001). 
Description of Study Area 3

Purpose and Scope

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

of groundwater quality in 2009 in the four primary aquifers 

used in Geauga County, (2) describe the detection frequency 

of methane in water wells in the county in 2009, and (3) 

determine whether statistically significant changes in water 

quality had occurred since 1978. To determine the status 

of groundwater quality in 2009, USGS personnel collected 

samples from 16 domestic wells during June 9–19, 2009. 

These analyses were augmented with water-quality data from 

seven public-supply well fields collected during 2000–2010 

and on file with the Ohio Environmental Protection Agency 

(Ohio EPA). Water-quality analyses from both sources were 

compared to health-based and aesthetically based drinkingwater benchmarks to identify present-day constituents of 

concern (manmade or naturally occurring groundwater 

contaminants) in Geauga County groundwater. To determine 

the detection frequency of methane in water wells in the 

county, water from each of the 16 domestic wells sampled 

in 2009 was screened for combustible gases, with a positive 

detection prompting laboratory analysis for dissolved methane. 

Changes in water quality over time were evaluated by (1) 

statistically comparing constituent concentrations in samples 

from 1999 to those of 2009 for the 16 domestic wells that were 

able to be sampled by the USGS in both years, (2) assessing 

the statistical relation between constituent concentration and 

sampling year using all USGS water-quality data for the 

county—as many as 116 samples collected in 1978, 1980, 

1986, 1999, and 2009 from 65 wells—and (3) examining 

detection frequencies of selected constituents by year. Finally, 

data from all 116 USGS samples were used to assess whether 

factors such as depth to groundwater, well location, well 

elevation, aquifer tapped by well, or well construction were 

correlated to constituent concentrations in groundwater. Such 

knowledge may help well owners and planners understand 

where specific constituents of concern might occur. 

Description of Study Area

Geauga County is in northeastern Ohio and covers 

approximately 409 square miles (mi2) (fig. 1) The hilly 

topography and location relative to Lake Erie cause moistureladen winds from the lake to release rain and snowfall on the 

Geauga County uplands. Average annual precipitation for the 

period 1971 to 2000 ranged from 40.2 inches per year (in/yr) 

near the south edge of the county to 46.4 in/year in Chardon 

and Hambden Townships, in the northern part of the county 

(PRISM Climate Group, 2006). Characteristics of the study 

area with the potential to influence groundwater quality are 

described in the following paragraphs.

Aquifers and Directions of Groundwater Flow

Aquifers used to supply drinking water in Geauga 

County were mapped and described in detail by Eberts 

and others (1990). Directions of groundwater flow were 

determined by Eberts and others (1990) and Jagucki and 

Lesney (1995). These findings are briefly summarized below. 

Four main aquifers are utilized for drinking water in the 

county, including three layered bedrock units (the Pottsville 

Formation, Cuyahoga Group, and Berea Sandstone) and the 

overlying glacial sediments (fig. 2). Some of the bedrock 

layers have been eroded in stream valleys and along the edges 

of the county. Often the stream valleys are filled with glacial 

sediments, in some places to depths of more than 200 feet 

(ft). Precipitation is the source of virtually all groundwater 

within the county (Eberts and others, 1990). Under typical 

flow conditions, some precipitation will infiltrate from land 

surface to the water table, where it then flows downward and 

laterally over time through the hydraulically connected glacial 

sediments and Pottsville Formation. The Pottsville Formation 

consists of interbedded sandstones that readily transmit 

water. In some places, however, discontinuous patches of 

shale are present between sandstone layers that locally inhibit 

downward groundwater movement. Water flowing through the 

glacial sediments and the Pottsville Formation may discharge 

to nearby streams (figs. 1A and 2), creating isolated flow cells 

on each hilltop. 

Not all groundwater in the Pottsville Formation 

discharges to local streams; some groundwater reaches the 

base of the Pottsville Formation and flows downward into the 

underlying Cuyahoga Group, which is a thick sequence of 

interbedded shales and sandstones that is much less permeable 

than the surrounding bedrock layers. At shallow depths and 

where much overlying rock has been eroded (as is shown at 

the eastern edge of fig. 2), the Cuyahoga Group is fractured 

and groundwater flows horizontally through the fractures, 

joints, and bedding planes; however, through most of the 

formation’s thickness, groundwater flow is almost vertical and 

the formation acts as a leaky confining unit, greatly slowing 

the movement of water into lower layers. Once through the 

Cuyahoga Group, water enters the underlying Berea Sandstone 

and resumes flowing in a primarily lateral direction and at a 

relatively rapid rate compared to that in the Cuyahoga Group. 

The direction of groundwater flow in the Berea Sandstone is 

generally from the center of the county toward the outer edges 

of the county (fig. 1B), where it discharges into major stream 

valleys and to springs. It is primarily near these discharge 

areas along the outer edges of the county—where overlying 

aquifers have been eroded (fig. 2)—that the Berea Sandstone 

is tapped for drinking water. The groundwater residence time, 

or time that it takes for groundwater to travel from the water 

table to various discharge points at streams and springs, is 

shown in figure 2, as estimated by Eberts and others (1990) 
4 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

0

5 10

5

0 KILOMETERS

10 MILES

Base for both maps is from U.S. Geological Survey1:24,000 Digital Data and 1:24,000 mylarAlbers Equal-Area Conic projectionStandard parallels 30°50’ and 41°10’, central meridian -84°

Water-table contours modified from Jagucki and Lesney, 1995

Water-table contours from Jagucki and Lesney, 1995

41°30’

41°37’30”

41°22’30”

41°30’

41°22’30”

81°15’

81°22’30”

81°7’30”

41°37’30”

81°15’

81°22’30”

81°7’30”

Grand

River

River

River

River

River

Chagrin

LaDue

Reservoir

East

Branch

Reservoir

East

Branch

Branch West

Cuyhoga

Cuyahoga

Cuyahoga

Grand

River

River

River

Chagrin

LaDue

Reservoir

East

Branch

Reservoir

East

Branch

Branch West

Cuyahoga

Cuyahoga

Cuyahoga

River

Troy

Thompson

Montville

Huntsburg

Claridon

Munson

Chester

Burton

Thompson

Middlefield

Hambden

Claridon

Auburn

Parkman

Bainbridge

Russell

Chester

Chardon

Munson

Huntsburg

Burton

Montville

Parkman Troy

Middlefield

Bainbridge

Auburn

Newbury

Chardon Hambden

Newbury

Russell

EXPLANATION

1250 Water-table contour

—Shows altitude of water table. 

Dashed where inferred. Contour interval 50 feet.

Generalized direction of groundwater flow

Approximate location of Berea Sandstone outcropor subcrop beneath glacial deposits

—From Eberts 

and others, 1990, pl. 1

A A’ Trace of geologic section

—Generalized section 

from Eberts and others, 1986 (see fig. 2)

Figure 1. Groundwater levels and direction of flow in Geauga County, Ohio, September 6-9, 1994. A, In the Pottsville Formation and glacial deposits. B, In the Berea Sandstone. 

1250

1250

1150

1050

1050

1150

950

1050

1150

1150

1150

1150

1150

1050

1200

1200

1200

1200

1100

1100

1100

1000

1100

1050

1150

1050

1050

1100

1000

1000

1100

1050

950

950

900

1000

1050

950

1100

1200

1100

1100

1000

1100

1150

1200

1200

1200

1250

1150

1150

1000

A. B.

A A’

Cleveland

Figure 1. Groundwater levels and direction of flow in Geauga County, Ohio, September 6–9, 1994. 

A, In the Pottsville Formation and glacial deposits. 

B, In the Berea Sandstone. 
Description of Study Area 5

fig2

Chester Twp. Huntsburg Twp.

1400

690

40

15

45

15

50

380

60

2 30

120

WEST

A

FEET

A ́

EAST

FEET

1,400

1,300

1,200

1,100

1,000

900

800

700

600

500

1,400

1,300

1,200

1,100

1,000

900

800

700

600

500

VERTICAL SCALE GREATLY EXAGGERATED

DATUM IS NGVD 29

EXPLANATION

Simulated groundwater flow path—

Number, where shown, is simulated groundwater 

residence time, in years

Berea Sandstone (Mississippian)

Pre-Berea sedimentary rocks, 

including the Bedford Shale (Mississippian 

and Devonian)

Undifferentiated glacial deposits (Quaternary)

Pottsville Formation (Pennsylvanian)

Cuyahoga Group (Mississippian)

0 1 2 3 4 5 6 MILES

0 1 2 3 4 5 6 KILOMETERS

East Branch Chagrin River

Chagrin River

West Branch Cuyahoga River 

East Branch Cuyahoga River

Figure 2. Generalized geologic section of Geauga County, Ohio (modified from Eberts and others, 1990). Trace of section A–A’ 

is shown on figure 1.

using a computer model to simulate groundwater flow. The 

amount of residence time can affect water quality; the longer 

groundwater is in contact with aquifer materials, the more 

minerals dissolve into groundwater and the more oxygen 

depleted the groundwater becomes.

Annual Precipitation

The amount of precipitation in the year preceding a 

groundwater-sampling event can affect water quality—

particularly in shallow wells that receive direct recharge 

from precipitation infiltration to the water table. Precipitation 

amounts in the calendar year prior to the 1978, 1980, and 1986 

sampling rounds were roughly comparable, at about 5 inches 

(in.) above normal (fig. 3). Only the sampling round in 1999 

was preceded by 1 or more years of below-normal rainfall. 

The 2009 sampling round was unique, in that precipitation was 

4.33 to 10.74 in. above normal for 6 consecutive years prior to 

groundwater-sample collection (fig. 3). Above-normal annual 

rainfall increases recharge and can either dilute constituent 

concentrations in shallow groundwater or add dissolved 

constituents from a source at land surface. 

Land Use and Population 

Increasing population brings with it a greater potential for 

harmful human effects on groundwater resources, including 

larger groundwater withdrawals and potential contamination 

from a greater number of septic systems, roads treated 

with deicing salt, and industrial and retail facilities that use 

solvents, pesticides, and other chemicals. An estimated 26,646 

people lived in Geauga County in 1950 (U.S. Census Bureau, 

2014), compared to 99,060 residents in 2009 (U.S. Census 

Bureau, 2010). Population growth was most rapid during 

the 1950s and 1960s (fig. 4), when population increased by 

36,331 people. It took another 39 years (1970 to 2009) for 

an additional 36,083 people to be added to the county (U.S. 

Census Bureau, 2014), with population growth being slowest 

during the 1980s. The average population density of the 

county increased from 184 persons per square mile in 1980 

to 245 in 2009 (roughly the period for which water-quality 

data are available). Population density varies widely, with the 

townships in the western part of the county being historically 

the most densely populated (fig. 5) and continuing to develop 

(fig. 6) because of their proximity to Cleveland and Cuyahoga 

County. 
6 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

EXPLANATION

Annual precipitation

-10

-5

0

5

10

15

20

25

1975 1980 1985 1990 1995 2000 2005 2010

Year

Annual precipitation departure from normal, in inches

1978 sampling

1980 sampling

1986 sampling

1999 sampling

2009 sampling

. 3

Figure 3. Variation in annual precipitation in Northeast Ohio relative to timing of water-quality sampling by the 

U.S. Geological Survey in Geauga County Ohio, 1978–2009. (Annual precipitation data are departure from normal 

for the climatological Northeast Region of Ohio [Ohio Department of Natural Resources, 1976–2013]. “Normal 

precipitation” and plotting conventions are described in appendix 1.)

0

5,000

10,000

15,000

20,000

1950s 1960s 1970s 1980s 1990s 2000s

25,000

Number of people added each decade

Figure 4. Number of people added 

each decade in Geauga County, 

Ohio, 1950–2009. (Data from 

U.S. Census Bureau, 2010, 2014.)
Description of Study Area 7

#

#

#

#

#

#

##

#

#

#

#

#

#

#

#

!

!

!

! !

!

!4

7

1 2

5

3

6

GE-77

GE-108

GE-109

GE-126

GE-341

GE-332

GE-234

GE-202

GE-165 GE-151

GE-147

GE-141

GE-120

GE-103

GE-85A

GE-185A

Troy

Auburn

Burton

Russell

Munson

Newbury

Chardon

Parkman

Chester Claridon

Montville

Thompson

Bainbridge

Hambden

Huntsburg

Middlefield

Population distribution modified from

U.S. Census Bureau, Geography Division, 2009.

#

!

GE-77

0 5 MILES

0 5 KILOMETERS

Base from U.S. Geological Survey

1:24,000 data

2

81°20'

81°10'

41°30'

41°40'

Water-quality site and well name for wells sampled by the 

U.S. Geological Survey in 2009 (see table 3)

Public-supply well and well identifier for wells evaluated 

in this report (see table 4)

Population per 30-meter pixel

High: 10.4

Low: 0

EXPLANATION

Cleveland

GEAUGA

CUYAHOGA

Figure 5. Population density in Geauga County, Ohio, 2000, based on the 2000 Census Blocks and the 2001 National 

Land Cover Database.
8 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

fig 6

Agriculture or Forest to Urban

Agriculture or Forest to Wetland

Agriculture to Forest or Grass/shrub

Forest to Agriculture

Forest to Grass/shrub or Barren

Other

Changed during 1992−2001

EXPLANATION

Same in 1992 and 2001

Agriculture 

Barren

Forest 

Grass/shrub 

Open water 

Wetland 

Urban 

Base from U.S. Geological Survey

1:24,000 data

0 5 MILES

0 5 KILOMETERS

Land-cover data from U.S Geological Survey

National Land Cover Database 1992–2001

Retrofit Land Cover Change Product

(Fry and others, 2009) 

81°20'

41°30'

41°40'

81°10'

Cleveland

Figure 6. Land-cover change in Geauga County, Ohio, 1992 to 2001.
Description of Study Area 9

Unfortunately, differences in how land use has been 

categorized over the years—particularly large-lot residential 

properties—makes it difficult to compare land use from several decades ago to that of recent years. Total land cover acreage per category changed little between 1992 and 2001 (fig. 

6), years in which comparable data could be obtained. Less 

than 2 percent of land that was in agriculture or forest in 1992 

was converted to developed land cover by 2001, and about 1.4 

percent of land that was in agriculture in 1992 was converted 

to forest, grassland, or shrub by 2001. 

In 2001, about 16 percent of Geauga County’s area was 

developed land, though mainly consisting of open space such 

as the lawns of large-lot single-family houses, golf courses, 

and parks (table 1). Almost half of the area of the county was 

forested, and agriculture accounted for about 25 percent of the 

county’s area. It is estimated that only 2.9 percent of the surface of Geauga County was covered with impervious materials 

such as rooftops, roads, and parking lots in 2001. 

Water Use

County water use was first estimated in 1975 by compiling withdrawal data from water utilities, rural homeowners, 

industrial and commercial facilities, and irrigators. Total 

groundwater withdrawals have increased over time, from an 

estimated 4.9 million gallons per day in 1975 (Hathaway and 

Eberle, 1981) to 7.1 million gallons per day in 2005 (Kenny 

and others, 2009). An increase in groundwater withdrawals 

can cause groundwater levels to decline and can potentially 

affect water quality by drawing water into a well from different aquifers or parts of an aquifer than were accessed when 

smaller volumes of water were pumped. 

In 2005, the majority of groundwater (79 percent) 

used in the county was self-supplied water withdrawn from 

domestic wells for purposes of drinking, food preparation, 

washing, flushing toilets, and watering lawns and gardens 

(Kenny and others, 2009). Unlike drinking water supplied by 

Table 1. Percentages of land-cover types and impervious area, by township, Geauga County, Ohio, 2001.

[Impervious and land-cover data from National Land Cover Database (Homer and others, 2007)]

Township

Percent 

developed 

impervious1 

(not a 

subset of 

land-cover 

type)

Percent land-cover type2

Developed

AgricultureGrass/

shrub Forest Open water Open Wetland Other

space

Low 

intensity

Medium 

or high 

intensity

Auburn 2.1 8.4 3.3 0.5 25.5 6.8 46.4 8.0 1.2 0.0

Bainbridge 6.7 24.2 9.9 2.3 9.9 7.3 45.0 1.0 0.4 0.1

Burton 2.3 7.7 3.7 0.7 27.7 6.0 42.9 3.2 7.8 0.4

Chardon 4.5 12.2 7.3 1.7 8.9 8.5 60.8 0.5 0.2 0.1

Chester 6.8 32.3 10.5 1.0 5.0 11.3 39.4 0.2 0.2 0.1

Claridon 1.2 5.3 1.6 0.3 31.5 6.7 50.2 1.3 3.0 0.0

Hambden 2.0 7.1 3.2 0.5 21.8 9.4 57.0 0.7 0.3 0.0

Huntsburg 1.1 2.9 2.7 0.0 41.4 4.6 42.9 2.8 2.2 0.5

Middlefield 4.1 5.2 6.2 2.3 48.1 5.6 30.1 0.7 1.6 0.2

Montville 0.9 4.0 1.5 0.1 24.1 5.2 58.9 1.9 3.5 0.6

Munson 3.1 16.8 4.5 0.5 11.1 10.8 51.0 2.5 1.8 1.0

Newbury 3.0 10.8 4.5 1.0 17.1 7.7 54.9 2.9 1.1 0.0

Parkman 1.1 5.8 1.7 0.2 44.9 4.3 41.9 0.6 0.3 0.3

Russell 4.9 27.7 7.2 0.4 5.9 5.8 51.1 0.7 1.2 0.1

Thompson 1.0 2.9 2.3 0.1 34.4 5.6 53.2 0.5 0.5 0.5

Troy 1.0 4.4 1.6 0.1 38.5 3.1 41.9 4.3 5.9 0.2

Total 2.9 11.0 4.5 0.7 24.8 6.8 47.9 2.07 1.9 0.3

1

 Percent impervious and land-cover classes are determined by the spectral signatures of the Landsat satellite sensors. The classes of developed land cover 

are derived from the percent developed impervious as follows: developed open space, less than 20 percent impervious; developed low intensity, 20–49 percent 

impervious; developed medium or high intensity, greater than 50 percent impervious.

2

 Summed land-cover percentages for a township may not total 100 percent because of rounding.
10 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

public-supply wells (wells that serve 25 or more individuals for at least 60 days a year and have regular water-testing 

requirements regulated by Ohio EPA), water from domestic 

wells is not safeguarded by mandatory periodic testing of 

water quality but instead relies on voluntary testing contracted 

by homeowners. 

Groundwater Levels 

The long-term groundwater-level monitoring network in 

Geauga County consists of 31 wells that tap the four primary 

aquifers used in the county (fig. 7). Water levels in network 

wells were measured six times a year during 1996–2012 and 

four times a year thereafter. Continuous (hourly) water levels 

have been recorded in a subset of six wells shown as pink 

circles in figure 7. Hydrographs (plots of water-level changes 

over time) for all network wells are available at http://groundwaterwatch.usgs.gov/countymap.asp?sa=OH&cc=055.

Water Levels, 1978–1994

 Intermittent water-level data from previous studies 

(Nichols, 1980; U.S. Geological Survey, 1981; Eberts and 

others, 1990) are available for 13 of the 31 network wells 

(denoted by squares in fig. 7), beginning in 1978, 1980, 1985, 

or 1986. Hydrographs for these 13 wells are shown relative 

to fluctuations in annual precipitation in appendix figures 

1–1A and B. Visual inspection of these plots indicates that 

intermittent water-level data collected at network wells during previous studies can be classified as either (a) shallower 

than expected on the basis of historic precipitation variations, 

indicating that water levels have declined over time in the 

vicinity of the well (fig. 7, hydrograph A), or (b) within the 

depth range expected on the basis of historic annual precipitation data (denoted by orange squares in fig. 7, and exemplified 

by hydrograph B)—meaning that water levels in the late 1970s 

and 1980s were comparable to water levels in the late 1990s 

and 2000s. In 10 of the 13 wells with intermittent data from 

previous studies, water levels declined in the 1980s (denoted 

by green squares in fig. 7). Water-level declines occurred at 

wells in several townships and in wells tapping each of the 

four primary aquifers (fig. 7). 

Water-level declines in the 1980s were likely much more 

widespread than indicated by just the 10 wells with green 

squares (fig. 7). Quantification of water-level fluctuations in 

network wells due to variations in annual precipitation has 

allowed reinterpretation of water-level comparisons (1986 to 

1994) made by Jagucki and Lesney (1995). The conclusion of 

this reinterpretation (appendix 1) is that water-level declines 

of 1 ft or more measured between 1986 and 1994 in 50 of 

88 wells (57 percent) were not a response to fluctuations in 

annual precipitation amounts. Instead, water levels measured 

in the 1980s in these wells were likely still adjusting to the 

rapid population growth (fig. 4) and the associated increased 

groundwater withdrawals that occurred from 1950 to 1970. 

Declines likely began before water levels were first measured, 

with slowing population growth in the 1980s allowing water 

levels in most wells to stabilize by the mid-1990s. A second contributing factor to the observed water-level declines 

in some wells could be the magnitude 5.0 earthquake that 

occurred on January 31, 1986 (epicenter just north of Hambden Township, fig. 7). This earthquake may have created 

new bedrock fractures that increased aquifer drainage and 

discharge (appendix 1). Jagucki and Lesney (1995) noted that 

water-level declines between 1986 and 1994 occurred in all 

four aquifers but that the greatest water-level declines (more 

than 10 ft) were measured primarily in wells tapping the 

Cuyahoga Group and Berea Sandstone.

Water Levels, 1996–2012

During 1996–2012, water levels in most wells were 

stable, with fluctuations mimicking variations in annual 

precipitation. However, water levels in 4 of the 31 network 

wells—GE-119, GE-136, GE-349, and GE-352—began 

declining sometime after 1996 (appendix fig. 1–1C). In most 

cases a new pumping source, drilled at about the same time 

that the water-level decline began, was identified near the 

network well. The difference in average water level before and 

after a decline ranged from about 0.5 to 5.2 ft. These “recent” 

water-level declines have been noted in three aquifers—the 

glacial deposits, Pottsville Formation, and Cuyahoga Group. 

Three of the four wells where water levels recently declined 

are in Middlefield Township. The water level in an additional 

well in Middlefield Township (GE-147, fig. 5), which is not 

part of the long-term groundwater-level network but has been 

periodically measured prior to water-quality sampling, began 

to decline prior to 1986 and has continued to decline significantly in recent years (table 2).

Table 2. Water levels in well GE-147, Middlefield 

Township, Geauga County, Ohio, 1975–2009.

Date Depth to water, in feet below land 

surface

1/31/1975 Overflowing1

4/30/1986 1.26

6/16/1999 6.72

6/16/2009 18.52

1

This measurement is from the driller’s well log.
Description of Study Area 11

Map EXPLANATION

Well completed in glacial depositsWell completed in Pottsville FormationWell completed in Cuyahoga GroupWell completed in Berea Sandstone

Data show no water-level decline in the 1980s

Data show a water-level decline in the 1980s

Wells with periodic water-level measurements prior 

to 1994 (data plots are in appendix 1):

Hydrograph EXPLANATION

January 31, 1986, earthquake

Annual precipitation

 Water level

Well instrumented to continuously 

record water levels

BAINBRIDGE

NEWBURY

AUBURN

CLARIDON

BURTON

TROY

THOMPSON

MONTVILLE

MIDDLEFIELD

HUNTSBURG

PARKMAN

HAMBDEN

41o22'30"

81o07'30"

CHESTER

RUSSELL

CHARDON

MUNSON

41o30'

81o22'30"

41o37'30"

81o15'

0

0

4 MILES

4 KILOMETERS

2

2

Base from U.S. Geological Survey digital data, 2007

GE-352

GE-343

GE-202

GE-106

GE-103

GE-262

GE-280

GE-112

GE-349

GE-136

GE-119

GE-163

GE-139

GE-22 GE-350

GE-23

GE-170

GE-332

GE-365

GE-366

GE-354

GE-338

GE-351

GE-255

GE-150

GE-303

GE-308

GE-76

GE-185A

GE-357

GE-341

–15

–

–

10

5

0

5

25

20

1510

30323436384042

1975 1980 1985 1990 1995 2000 2005 2010 2015

,l ma r o m n orf er utr aped noi tat i p ci er P

es hcni ni

t fee ni ,r e wat o t ht peD

ecafr su nd al wol eb

GE-139 (Pottsville Fm.)

Year

–20

–10

0

3020

10

4042444648505254

1975 1980 1985 1990 1995 2000 2005 2010 2015

,l ma r o m n orf er utr aped noi tat i p ci er P

sehcni ni

t fee ni ,r e wat o t ht peD

ecafr su nd al wol eb

Year

GE-112 (Pottsville Fm.)

fig. 7

A

B

Figure 7. Long-term groundwater-level network in Geauga County, 2009, and comparison of water levels in selected wells, 1980-2012, to variations in annual precipitation, 1977–2012. (Annual precipitation data are departure from normal for the climatological Northeast Region of Ohio [Ohio Department of Natural Resources, 1977–2012]. “Normal precipitation” and plotting conventions are described in appendix 1.)
12 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Septic Systems and Licensed Land Application 

of Septage and Biosolids 

The observed increase in population in the county has 

been accompanied by increasing amounts of human waste 

requiring treatment. Approximately 70 percent of homes in 

the county have household sewage systems to treat domestic sewage and wastewater (Geauga County Health District, 

2010b). Most of these household systems discharge to on-lot 

leaching trenches, but about 19 percent of household treatment 

systems discharge off-lot (Mix, 2013). Point-of-sale household sewage-system inspections conducted between July 2002 

and December 2012 in Geauga County (prior to transfer of 

property ownership) indicated that 5 percent of on-lot systems 

were malfunctioning and 45.8 percent of off-lot discharging 

systems were malfunctioning (Mix, 2013). Failing off-lot 

systems were generally installed prior to 1991. Failing systems 

can increase the risk of contaminants entering groundwater 

(such as viruses, intestinal bacteria, and nitrates). In addition, 

elevated concentrations of orthophosphate, chloride, sodium, 

calcium, potassium, dissolved organic carbon, boron, and sulfate, and lowered dissolved oxygen content and pH have been 

measured in shallow groundwater beneath septic systems in 

other parts of the United States (Katz and others, 2011).

The application of domestic septage to agricultural fields 

is another potential source of groundwater contamination in 

Geauga County. Domestic septage refers to the solids and 

liquids that must be periodically pumped from septic tanks to 

keep them in proper working condition (Ohio Environmental 

Protection Agency and Ohio Department of Health, 2004). The 

most common way to dispose of septage in Geauga County 

is to transport it to a municipal wastewater treatment plant 

(Bob Weisdack, Geauga County Health Commissioner, 2011, 

written commun.). However, some septage haulers land-apply 

their waste at two registered sites (fig. 8) (Bob Weisdack, 

Geauga County Health Commissioner, 2011, written 

commun.), which are regulated by the Geauga County Health 

District.

 Thirty percent of the households in Geauga County 

receive public wastewater treatment services (Mix, 2013). 

Sewage from all villages and some individual subdivisions 

in the county is piped to wastewater treatment facilities, 

where processes are used to clean the wastewater and remove 

the solids. The treated solids, or sewage sludge, are called 

“biosolids” (U.S. Environmental Protection Agency, 2012). 

Biosolids are considered “Class A” if they are treated to a 

level that contains no detectible pathogens or “Class B” if 

detectible levels of pathogens are still present after treatment 

(U.S. Environmental Protection Agency, 2012). The most 

common way to dispose of biosolids in Ohio is to spread these 

organic-rich materials on agricultural fields, where they act as 

fertilizer to improve soils and stimulate plant growth (Ohio 

Environmental Protection Agency, 2006a). The fields shown 

in figure 8 are authorized by Ohio EPA for land application of 

Class B biosolids, although biosolids may never have actually 

been applied to a specific field. To determine whether a field 

has received Class B biosolids, the treatment plant to which 

the field is authorized must be contacted (see Ohio Environmental Protection Agency, 2010a). Regulations regarding 

application, monitoring, and recordkeeping are summarized by 

Ohio EPA and Ohio Department of Health (2004), U.S. Environmental Protection Agency (2012), and Mancl and others 

(1995). Detailed regulations governing the use and disposal of 

biosolids can be found in Code of Federal Regulations, Title 

40, Part 503 (1993).

Oil and Gas Drilling 

Geauga County has a long history of oil and gas drilling, 

with numerous existing or permitted (approved, but not yet 

completed) oil and gas wells (fig. 9). As of 2008, there were 

1,112 wells producing oil and (or) gas, 357 plugged wells, and 

535 permitted drilling sites (although 78 percent of these permits were expired) (Ohio Department of Natural Resources, 

2008a). About half (48 percent) of the oil and gas wells in 

the county were completed in the 1980s. Drilling activities 

slowed down in subsequent decades, with 13.5 percent of the 

wells in the county completed from 1990 through January 5, 

2008 (based on well completion dates in the Ohio Department 

of Natural Resources Oil and Gas Well Location Database 

(2008a). Twenty-six additional oil and gas wells were completed in the county in 2009, targeting primarily the Clinton 

Sandstone, with average well depths of about 4,000 ft below 

land surface (Ohio Department of Natural Resources, 2010a), 

which is much deeper than the aquifers used for water supply.

Although the environmental risks posed by oil and gas 

drilling are managed through Federal and State regulations, 

occasionally groundwater contamination does occur, and 

brines, crude oil, natural gas, volatile organic compounds 

(VOCs), and (or) drilling fluids to leak into aquifers. The 

Ohio Department of Natural Resources, Division of Mineral 

Resources Management (ODNR–MRM) has documented 185 

incidents of groundwater contamination caused by oil-field 

activities in Ohio from 1983 through 2007, with over half of 

the incidents occurring from 1983 through 1987 (Kell, 2011). 

The primary cause of groundwater contamination (44 percent 

of regulated1 incidents) has been inadequate construction or 

maintenance of earthen-bermed reserve pits, which are excavated adjacent to a drilling rig to hold drilling muds and fluids. 

ODNR–MRM investigations in the 1980s found that some 

pits were either unlined or had thin, easily torn liners (Kell, 

2011). Prior to 1985, earthen pits also were used after drilling 

was completed, to store the large volumes of brine that are 

coproduced with oil and gas (Kell, 2011). New standards for 

construction of reserve pits in contamination-sensitive areas in 

northeastern and north-central Ohio were authorized in 1985 

as part of Amended Substitute House Bill 501; this same bill 

eliminated produced-water earthen pits throughout the state as 

of July 1, 1986 (which, at the time, numbered in the thousands 

1

 Regulated incidents are those not involving an orphaned well, which is an 

inactive well with no responsible party to plug the well.
Description of Study Area 13

GE-77

GE-108

GE-109

GE-126

GE-341

GE-332

GE-234

GE-202

GE-165 GE-151

GE-147

GE-141

GE-120

GE-103

GE-85A

GE-185A

168

700

528

86

166

306

44

608

88

87

44

422

322

6

Chagrin River

Cuyahoga River

Grand River

Troy Auburn

Russell Burton

Munson

Newbury

Chester

Chardon

Parkman

Claridon

Montville

Thompson

Bainbridge

Hambden

Huntsburg

Middlefield

4

7

1 2

5

3

6

81°10'

81°20'

41°40'

41°30'

GE-108

2

Water-quality site and well name 

for wells sampled by the U.S. 

Geological Survey in 2009 (see 

table 3)

Public-supply well and well 

identifier for wells evaluated 

in this report (see table 4) 

Fields approved for septage 

application

Fields approved for biosolids 

application

EXPLANATION Cleveland

0 5 MILES

0 5 KILOMETERS

Digital data variously scaled

Universal Transverse Mercator, zone 17

Biosolids data modified from 

Ohio Environmental Protection Agency, 2010a

Septage data modified from

Geauga County Health District, 2011, written commun.

Figure 8.

Figure 8. Authorized biosolids application sites in Geauga County, 2009, and registered septage-spreading sites, 2011.
14 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

4

7

1 2

5

3

6

GE-77

GE-108

GE-109

GE-126

GE-341

GE-332

GE-234

GE-202

GE-165 GE-151

GE-147

GE-141

GE-120

GE-103

GE-85A

GE-185A

81°10'

81°20'

41°40'

41°30'

Figure 9.

EXPLANATION

Oil and gas data from Ohio Department 

of Natural Resources, 2008a

GE-77

Base modified from U.S. Geological Survey

1:24,000-scale digital data

2

Water-quality site and well name for wells 

sampled by the U.S. Geological Survey in 2009 

(see table 3)

Public-supply well and well identifier for wells 

evaluated in this report (see table 4) 

Active Class II injection wells

Plugged well

Permitted location

Producing well

Cleveland

0 5 MILES

0 5 KILOMETERS

 Figure 9. Oil and gas wells and active Class II injection wells in Geauga County, 2008.
Water-Quality Issues Identified in Previous Investigations 15

in Ohio), and established permitted Class II injection wells as 

the preferred method to dispose of brines. 

In 2010, approximately 98 percent of oil-field fluids in 

Ohio were disposed of in Class II injection wells (and were 

stored in tanks prior to disposal), and 2 percent of oil-field 

fluids were spread on county, township, and village roads for 

dust and ice control (Tomastik, 2010). In Geauga County, only 

one Class II injection well, in Montville Township, was used 

in 2011 for brine injection. A second Class II injection well, in 

Hambden Township, was shut down in 2011 for “housekeeping issues” (Tom Tomastik, ODNR–MRM, written commun., 

2011). Local authorities have authorized spreading of brine 

on roads in Auburn, Huntsburg, Middlefield, Parkman, and 

Thompson Townships in Geauga County (Tom Tomastik, 

ODNR–MRM, oral commun., 2010); this spreading is regulated by ODNR–MRM.

Road Deicing 

Increasing population and development activity led to 

the addition of about 157 miles of roads in Geauga County 

between 1981 and 2008 (Geauga County Engineer’s office, 

written commun., 2011). Most of the added roads were 

township roads, which increased in mileage by more than 

35 percent during this period. Increased road mileage has led 

to greater amounts of road salt being purchased over time 

by the County Engineer2 for application to remove snow and 

ice (fig. 10). The spreading of road salt and oil-field brines 

on roads both have the potential to add salinity (sodium and 

chloride) and dissolved solids to shallow groundwater and to 

increase specific conductance. Calcium chloride has been used 

to a lesser extent than sodium chloride as a deicing chemical 

in Ohio (Kunze and Sroka, 2004), and also could contribute 

calcium to shallow groundwater. 

The Ohio Department of Transportation (ODOT) has 

tracked its road salt use in the county since 1999 (fig. 10). 

These data indicate that application rates fluctuated from 1991 

through 2011 but did not show an overall increase. However, 

ODOT services only State routes through the county, which 

have had consistent mileage since the 1980s—it is the 

township roads that have increased in mileage over time as 

population has increased. ODOT does not spread oil-field 

brines on roads (Ohio Department of Transportation, written 

commun., 2011). 

2

 The County Engineer purchases salt for 9 of the 16 townships in the 

county. Road salt purchased by Chester, Russell, Bainbridge, Auburn, 

Newbury, Munson, and Chardon Townships and the various municipalities 

in the county are not included in totals shown in figure 10.

Water-Quality Issues Identified in 

Previous Investigations 

Jagucki and Darner (2001) summarized previous 

studies of groundwater quality in Geauga County done 

for various purposes and at various scales. These studies 

consistently reported that manganese and iron concentrations 

in groundwater in the county often exceed the aesthetically 

based Secondary Maximum Contaminant Levels (SMCLs) 

of 50 micrograms per liter (μg/L) and 300 μg/L, respectively, 

established by the U.S. Environmental Protection Agency 

(USEPA; 2009) for drinking water. VOCs and indicators 

of road salt and, less commonly, oil-field brines have 

been detected in groundwater at isolated locations. Nitrate 

concentrations in groundwater at some locations have been 

indicative of the effects of fertilizer application or effluent 

from septic systems, but concentrations have not exceeded the 

health-based USEPA Maximum Contaminant Level (MCL) of 

10 milligrams per liter (mg/L) as nitrogen (N).

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

1990 1995 2000 2005 2010

Road salt, in tons

Year

EXPLANATION

County Engineer's road-salt 

purchases (writtten 

commun., 2011)

Ohio Dept. of Transportation 

road-salt use (written 

commun., 2011)

Figure 10. Road-salt use in Geauga County, Ohio, 1991–2011.
16 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Groundwater Affected by Localized Chemical 

and Gas Releases

Multiple entities investigate complaints of groundwater 

affected by commercial and industrial activities, including 

Ohio EPA Division of Environmental Response and 

Revitalization (DERR), Ohio EPA Division of Drinking and 

Ground Waters, the Geauga County Health District (which 

investigates complaints by domestic well owners), and 

ODNR–MRM (which examines complaints of contamination 

related to oil and gas drilling). Sites in Geauga County 

for which the authors obtained agency documentation that 

groundwater has been affected by localized chemical and 

gas releases are shown in figure 11 and summarized below. 

Additional sites may exist. The aquifer or aquifers affected 

at each site are specified in the following summaries, if that 

information was documented by the investigating agency.

Jagucki and Darner (2001) examined the files of Ohio 

EPA DERR and found four principal sites of documented 

groundwater contamination in Geauga County between 1984 

and 1996 (fig. 11, sites 1–4). At sites 1 and 2 in Bainbridge 

Township, the Pottsville Formation and the Berea Sandstone 

were contaminated with VOCs such as trichloroethene 

(TCE), 1,1,1-trichloroethane (TCA), perchloroethene 

(PCE), and benzene. Groundwater at site 3 in Bainbridge 

Township contained TCA and benzene, plus diethyl ether 

and 1,2-dichloroethane (DCA). Water lines were extended 

from Cuyahoga County to provide municipal drinking water 

for residents at these sites in response to the contamination. 

Groundwater in both the Pottsville Formation and the Berea 

Sandstone at site 4 in Chester Township was contaminated 

with gasoline compounds. In addition, high chloride 

concentrations in groundwater at site 4 were attributed to 

road salt. As a result, leaking underground storage tanks 

were removed or replaced, and road-salt storage piles in 

this area were underlain with asphalt and covered with an 

enclosure. Details of the investigations at sites 1 through 4 are 

summarized by Jagucki and Darner (2001). 

 Descriptions of groundwater contamination at sites 5 

through 8 (fig. 11) were obtained from a database of sites 

investigated by Ohio EPA, Division of Drinking and Ground 

Waters (2010b) (referred to as the “Groundwater Impacts 

Database”). The source of VOC contamination at site 5 was a 

chemical spill which occurred in 1980 in Russell Township. 

Groundwater samples collected from wells in the Pottsville 

Formation from 1986 to 2006 contained VOCs including cis1,2-dichloroethene at a concentration 4 times the MCL, and 

TCE and vinyl chloride at concentrations more than 50 times 

MCL. The primary means of remediation has been natural 

attenuation (Ohio Environmental Protection Agency, 2010b).

Investigations that began in 1994 at an industrial site 

near the south edge of the Village of Middlefield (fig. 11, 

site 6) identified two distinct plumes of contamination in 

the Pottsville Formation. Contaminants were primarily 

chlorinated solvents, including TCE, PCE, TCA, DCA, and 

1,2-dichloroethene (DCE). Contamination was also detected in 

two offsite residential wells and one nearby commercial well 

in 2001. Both residences were connected to the Middlefield 

public water supply in 2001 (U.S. Department of Health and 

Human Services, 2004). A pump and treat system consisting of 

two extraction wells was installed in 2002 to reduce the levels 

and extent of contamination.

Groundwater contamination at site 7 (fig. 11) was 

investigated in 2001 in Parkman Township, in the southeastern 

corner of the county. Leaking underground storage tanks 

were determined to be the source of benzene to shallow 

groundwater in glacial deposits overlying the Pottsville 

Formation at this location. Contamination was found to have 

moved offsite, and one public-supply well to the east was 

affected. Monitoring wells were installed, and the maximum 

benzene concentration found was 432 μg/L, greatly exceeding 

the MCL of 5 μg/L. Primary remediation has been fluid and 

vapor extraction (Ohio Environmental Protection Agency, 

2010b).

Ohio EPA sampled groundwater beneath a mixed 

industrial and commercial facility in Newbury Township from 

2005 to 2008 (fig. 11, site 8). Anaylses detected chromium, 

lead, and five VOCs (cis-1,2-dichloroethene, TCE, DCA, 

1,2-dichloroethane, and vinyl chloride) in the glacial deposits 

but not in the underlying Pottsville Formation. Aboveground 

storage tanks, ponds, and a dumping area were determined 

to be the source of contamination. Removal of contaminated 

sediments was the primary means of remediation (Ohio 

Environmental Protection Agency, 2010b).

A completed oil and gas well in Bainbridge Township 

was determined by ODNR–MRM (2008b) to be the source of 

a natural gas invasion to the Pottsville Formation, Cuyahoga 

Formation, and Berea Sandstone aquifers that occurred on 

December 2007 (fig. 11, site 9). Natural gas migrated from 

the aquifers into homes by way of water wells in basements 

(either unvented, in-use wells or abandoned but unplugged 

wells), causing one home to explode and 19 to be evacuated. 

Beginning in February 2008, water samples were collected 

and analyzed from 79 water wells. Natural gas was found 

in 23 water wells (22 private and one public-supply well). 

The highest concentration of dissolved methane found was 

1.04 mg/L. On the basis of a review of water-quality data, 

ODNR–MRM determined that groundwater had not been 

affected by oil-field brine, crude oil, or hydrofracture fluids. 

ODNR–MRM also noted that there was inadequate evidence 

to conclude that natural gas migrating through the aquifers 

had changed inorganic groundwater quality or had resulted in 

contamination of public water supplies (Ohio Department of 

Natural Resources, 2008b). 

An investigation by Ohio EPA of 14 domestic wells near 

the road-salt storage site on Mentor Road northwest from the 

City of Chardon (fig. 11, site 10) indicated that 9 wells in the 

area had been affected by road salt, on the basis of ratios of 

chloride to bromide found in groundwater from these wells. 

The road salt had been stored in a covered area, but cinders 

and salt had been mixed on a pervious surface for several 

years. Three of the homes had chloride concentrations in their 

wells in excess of the SMCL of 250 mg/L (Koziol, 2010).
Water-Quality Issues Identified in Previous Investigations 17

Chagrin River

Cuyahoga River

Grand River

Troy Auburn

Burton Russell

Munson

Newbury

Chester

Chardon

Parkman

Claridon

Montville

Thompson

Bainbridge

Hambden

Huntsburg

Middlefield

Chardon

South Russell

Middlefield

Burton

Aquilla

4

9

8

7

6

5

2

3

1

10

4

7

1 2

5

3

6

GE-77

GE-108

GE-109

GE-126

GE-341

GE-332

GE-234

GE-202

GE-165 GE-151

GE-147

GE-141

GE-120

GE-103

GE-85A

GE-185A

700 168 528

86

166

306

44

608

88

87

44

422

322

6

81°10'

81°20'

41°40'

41°30'

Figure 11.

Contamination location data from Ohio Environmental Protection Agency, 

Division of Drinking and Ground Waters, 2010b,

Ohio Environmental Protection Agency, Division of 

Environmental Response and Revitalization, 2012a.

Base modified from U.S. Geological Survey

1:24,000-scale digital data

EXPLANATION

GE-77

2

2

Site of documented groundwater contamination 

(location approximate) and site number as 

referred to in text

Water-quality site and well name for wells 

sampled by the U.S. Geological Survey in 2009 

(see table 3)

Public-supply well and well identifier for wells 

evaluated in this report (see table 4) 

Cleveland

0 5 MILES

0 5 KILOMETERS

GEAUGA

CUYAHOGA

Figure 11. Approximate location of sites in Geauga County, Ohio, where human effects on groundwater from industrial or commercial 

point sources have been documented.
18 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Methods of Study

Well Selection, Water-Quality Sampling 

Procedures, and Laboratory Analysis

To examine groundwater-quality conditions in 2009, the 

USGS sampled 16 wells from June 9 through June 19, 2009. 

Well locations are shown as green symbols in figure 12, latitudes and longitudes are given in appendix table 4–1, and well 

characteristics and constituents analyzed for are summarized 

in table 3. Fourteen of the sampled wells were domestic wells. 

Two wells were owned by very small public suppliers (defined 

as purveyors serving 25–500 people). These two wells provide 

water for a church (GE-341) and a golf course clubhouse 

(GE-85A). For simplicity, all 16 wells will be referred to as 

“domestic wells” in following text. The following criteria 

were used in selecting wells for USGS sampling:

1. Previous samples.—Efforts were made to resample wells 

from which the USGS collected water-quality data in 

both 1986 (Eberts and others, 1990) and 1999 (Jagucki 

and Darner, 2001) so that temporal changes in water 

quality could be assessed from a consistent set of wells. 

All 16 wells sampled in 2009 also were sampled in 1999, 

and 11 of the 16 wells also were sampled in 1986 (table 

3). Two wells had been consistently sampled since 1980.

2. Spatial distribution.—Wells were selected to provide 

broad spatial distribution within the county.

3. Stratigraphic distribution.—Wells completed in each of 

the primary stratigraphic units (fig. 2) were sampled in 

the quantities indicated: 3 in the glacial deposits, 5 in the 

Pottsville Formation, 5 in the Cuyahoga Group, and 3 in 

the Berea Sandstone. Only wells completed in a single 

stratigraphic unit were selected.

4. Likelihood of being affected by human activities.—

Although the first three criteria were emphasized during 

well selection, most of the wells available for sampling 

in both 1986 and 1999 were relatively deep wells in 

areas of low population density. Thus, efforts were made 

to select some wells that were likely to provide early 

detection of water-quality changes resulting from human 

activities at land surface. Desired characteristics were 

a shallow well depth or top of open interval that was 

within about 25 ft of the water table, young water (water 

in which tritium was detected in 1999, which is indicative of aquifer recharge that occurred since 1953), and a 

location in an area of relatively high population density 

or rapid population growth.

5. Ability to produce representative samples.—Final well 

selection was based upon an inspection of the well 

construction and plumbing system at each well to ensure 

that a representative sample of groundwater could be 

obtained.

Samples were collected by means of methods described 

in the “National Field Manual for the Collection of WaterQuality Data” (U.S. Geological Survey, 1997–present) and 

the “Quality-Assurance Plan for Water-Quality Activities in 

the USGS Ohio Water Science Center” (Francy and Shaffer, 2008). Samples were collected from household spigots; 

existing plumbing fixtures and well pumps were used. Well 

owners identified spigots that provided untreated water. USGS 

personnel were able to inspect the plumbing at 7 of the 16 

sites to verify that water from the spigots was untreated. It was 

possible to bypass the pressure tank for sampling at only two 

of the sites (GE-85A and GE-234, fig. 12, table 3). Ancillary 

data (such as distance of the well from the nearest road, age of 

septic system, frequency of septic tank pumping, use of well 

water, and land use) also were collected.

After arriving at the site, the field crew attached clean 

tubing to the sampling spigot and then connected the tubing to 

a flow manifold. Flow was diverted to a flowthrough chamber 

attached to a multiparameter sonde for measurement of pH, 

specific conductance, temperature, and dissolved oxygen. 

Turbidity was measured by using a separate turbidimeter. Even 

though all wells were in regular use, at least one well volume 

of water was purged before sampling to remove standing water 

from the well bore, pressure tank, and pipes and to ensure that 

samples reflected the chemistry of the water in the aquifer. 

Purging also served to condition the sampling equipment with 

well water. Sampling did not begin until sequential fieldmeasurement values met stabilization criteria described in the 

“National Field Manual for the Collection of Water-Quality 

Data” (U.S. Geological Survey, 1997–present, table 6.0–1). 

Before sampling, flow rate through the sampling line was 

reduced to 0.1 gallon per minute, leaving discharge through 

the other lines at the purge rate. The water was allowed to 

discharge at the purge rate to keep the pump from cycling off 

after the pressure tank was filled and to reduce the chance of 

backflow of water in adjacent plumbing lines. 

All groundwater samples were analyzed for alkalinity, 

specific conductance, pH, temperature, dissolved oxygen, 

turbidity, total sulfide, combustible gas, dissolved major and 

minor ions (including iron, manganese and bromide), dissolved arsenic, total dissolved solids, dissolved nutrients, 

dissolved pesticides, total coliform bacteria, and Escherichia 

coli (E. coli) bacteria. Fecal coliform and fecal streptococci 

bacteria also were analyzed for at wells previously sampled in 

1986 and in other selected wells. The dissolved trace elements 

cadmium, chromium, copper, lead, selenium, and zinc were 

analyzed for at four wells—one well from each of the four 

aquifers (table 3). On the basis of presence of flammable gas 

in sample headspace, water samples from three wells were 

analyzed for dissolved gases (table 3). Finally, two samples 

from wells tapping the Berea Sandstone were analyzed for 

tritium to augment tritium data collected in 1999.

Analyses for alkalinity, specific conductance, pH, temperature, dissolved oxygen, turbidity, sulfide and bacteria were 

done onsite by means of standard techniques described in the 

“National Field Manual for the Collection of Water-Quality 
Methods of Study 19

Figure 12. 

0 5 MILES

0 5 KILOMETERS

Troy Auburn

Russell Burton

Munson

Newbury

Chester

Chardon

Parkman

Claridon

Montville

Thompson

Bainbridge

Hambden

Huntsburg

Middlefield

Chagrin River

Cuyahoga River

Grand River

GE-77

GE-108

GE-109

GE-126

GE-341

GE-332

GE-234

GE-202

GE-165 GE-151

GE-147

GE-141

GE-120

GE-103

GE-85A

GE-185A

700 168 528

86

166

306

44

608

88

87

44

422

322

6

4

7

1

2

5

3

6

81°10'

81°20'

41°40'

41°30'

Base modified from U.S. Geological Survey

1:24,000-scale digital data

EXPLANATION

Data source and well identifier

U.S. Geological Survey, wells sampled in 

2009 (see table 3)

Ohio Environmental Protection Agency 

(2010e), Public Water Supply 

Compliance Database (see table 4)

Ohio Environmental Protection Agency 

(2010d), Ambient Well Network (see 

table 4)

Geologic unit

Glacial deposits

Pottsville Formation

Glacial deposits and Pottsville Formation

Pottsville Formation and possible 

Cuyahoga Group

Cuyahoga Group

Berea Sandstone

Cleveland

Figure 12. Data source and geologic unit of wells used to evaluate suitability of water for drinking, Geauga County, Ohio.
20 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009 Table 3. Characteristics of wells sampled by the U.S. Geological Survey in Geauga County, Ohio, June 2009, and constituents for which water samples were analyzed. [PWS, public water supply; USGS, U.S. Geological Survey; X, analyzed for; —, not analyzed for] Well name Well type Township Land- surface datum (feet) Aquifer Open interval1 (feet below land surface) Opening type Years previously sampled by USGS Constituents analyzed for in 2009 Top Bottom 1980 1986 1999

Standard 

analytes3

Fecal coliform

Fecal 

streptococci

Trace 

elements

Dissolved 

gases

Tritium

GE-77 Domestic Chester 1,140 Cuyahoga 80 155 Open hole

X

X

X

X

X

—

X

—

GE-85A Very small 

PWS

Newbury 1,220 Pottsville 72 140 Open hole

X

X

X

X

—

—

—

GE-103 Domestic Hambden 1,159 Berea 133 136 Screened

X

X

X

X

X

X

—

—

X

GE-108 Domestic Munson 1,120 Glacial 132 132 Open hole

X

X

X

X

X

X

—

—

—

GE-109 Domestic Munson 1,280 Pottsville 87.5 105 Open hole

X

X

X

X

X

X

—

—

GE-120 Domestic Chester 1,115 Berea 91 135 Open hole

X

X

X

X

X

—

—

—

GE-126 Domestic Parkman 1,070 Berea 136 200 Open hole

X

X

X

X

X

X

X

X

GE-141 Domestic Troy 1,118 Glacial 53 53 Open end2 X

X

X

X

X

X

—

—

GE-147 Domestic Middlefield 1,120 Cuyahoga 54 63 Open hole

X

X

X

X

X

X

X

—

GE-151 Domestic Auburn 1,268 Pottsville 62.2 148 Open hole

X

X

X

X

X

—

—

—

GE-165 Domestic Auburn 1,165 Glacial 56 56 Open end

X

X

X

X

X

—

—

—

GE-185A Domestic Chardon 1,269 Cuyahoga 70 90 Open hole

X

X

—

—

—

—

—

GE-202 Domestic Montville 1,259 Pottsville 49.4 74 Open hole

X

X

X

X

X

—

—

—

GE-234 Domestic Burton 1,170 Cuyahoga 40 80 Open hole

X

X

—

—

—

—

—

GE-332 Domestic Russell 1,181 Pottsville 48 104 Open hole

X

X

X

X

—

—

—

GE-341 Very small 

PWS

Thompson 1,267 Cuyahoga 71.7 120 Open hole

X

X

X

X

—

—

—

1 The open interval is the uncased portion of the well, through which water from the aquifer enters the well.2 Open-end wells are cased to the bottom of the well and have an open bottom that admits water. 3 All water samples were analyzed for alkalinity, specific conductance, pH, temperature, dissolved oxygen, turbidity, total sulfide, combustible gas, dissolved major and minor ions 

(including iron, manganese, and bromide), dissolved arsenic, total dissolved solids, dissolved nutrients, dissolved pesticides, total coliform bacteria, and Escherichia coli bacteria.
Methods of Study 21

Data” (U.S. Geological Survey, 1997–present). Water from 

each of the wells was screened for combustible-gas fraction 

at the wellhead and on the headspace of water samples. To 

measure combustible-gas fraction at the wellhead, the well 

cap was loosened and the tip of a combustible-gas indicator 

calibrated to 2 percent methane gas was inserted into the gap 

between the cap and well casing. To measure combustible-gas 

fraction in the headspace of water samples, the gas indicator 

was connected to a headspace chamber according to methods 

described by Chafin and others (1996, p. 9). The minimum 

reporting level (smallest concentration that can be reliably 

measured) of this screening method is 0.1 percent volume 

of combustible gas in the headspace. If combustible gas was 

detected at either the wellhead or in the headspace of a water 

sample, a groundwater sample was collected and sent to the 

USGS Chlorofluorocarbon Laboratory in Reston, Virginia, 

for analysis of dissolved gases (http://water.usgs.gov/lab/

dissolved-gas/). 

Tritium samples were analyzed by the USGS Tritium 

Laboratory in Menlo Park, California. Analyses for all other 

constituents were done by the USGS National Water Quality Laboratory (NWQL) in Denver, Colorado. The NWQL 

generally censored analytical results to the laboratory reporting level (LRL), as defined by Oblinger Childress and others 

(1999). Nondetections were reported as less than the LRL. 

Concentrations measured between the LRL and the long-term 

method detection level (Oblinger Childress and others, 1999) 

were reported as estimated concentrations. In this report, an 

estimated concentration is referred to as a “trace amount” of 

the constituent. 

Sample tubing and equipment were decontaminated after 

sampling at each well site as per standard methods (U.S. Geological Survey, 1997–present). Bacteria equipment was sterilized by autoclaving. Quality-control samples were collected 

at the rate of 10 percent to ensure sample integrity and final 

quality of data, as specified in the “Quality-Assurance Plan 

for Water-Quality Activities in the USGS Ohio Water Science 

Center” (Francy and Shaffer, 2008). Variability introduced 

by sample collection and laboratory analyses (represented by 

replicate samples) was compared to variability in constituent 

concentration between years. Types of quality-control samples 

and the method and frequency of collection are discussed in 

more detail in appendix 2. 

Public-Supply Well Data From the Ohio 

Environmental Protection Agency

Because many of the wells sampled by the USGS in 2009 

are in areas of relatively low population (fig. 5), water-quality 

data from 2000–2010 for selected public-supply well fields 

were obtained from Ohio EPA and used to evaluate recent 

water-quality conditions in more populated and developed 

areas where groundwater is more likely to be affected by 

human activities. Of almost 400 public-supply wells in the 

county, data from seven well-field locations were selected 

(fig. 12). These seven public-supply well fields were chosen 

on the basis of (1) availability of untreated water samples, 

(2) well fields serving the largest incorporated areas, and (3) 

well fields located in the more developed, western townships. 

Analyses of untreated water samples were preferred because 

the goal of this study is to evaluate the quality of the groundwater in the aquifers (source water) rather than exposure at the 

tap. Of the seven well fields chosen for evaluation, analyses 

of untreated water were available for the three well fields that 

are included in Ohio EPA’s Ambient Well Network (2010d): 

ASM International, Middlefield Village, and Tanglewood Lake 

(table 4, fig. 12). For the other four well fields evaluated in this 

report (table 4, fig. 12), water-quality data for treated samples 

and occasionally for untreated samples were obtained from 

Ohio EPA’s Safe Drinking Water Information System database 

(2010e), which contains all water-quality data submitted to 

Ohio EPA Division of Drinking and Ground Waters by Ohio 

public water systems and their certified laboratories to comply 

with legal monitoring requirements under the Safe Drinking 

Water Act (referred to in this report as “compliance data”). 

The only compliance data evaluated were those representing 

(a) water that was untreated or (b) water that was treated by 

a method that does not effectively remove the constituent of 

interest (unpublished data on file at the USGS Ohio Water 

Science Center, Columbus). 

Physical characteristics of public-supply well fields 

considered in this report are listed in table 4, along with the 

Ohio EPA database from which water-quality results were 

obtained, and available chemical analyses. Note that most 

samples from Ohio EPA’s compliance database represent water 

from more than one well blended together prior to analysis 

(with the exception of samples from Christ Presbyterian 

Church, table 4); samples of untreated water from Ohio EPA’s 

Ambient Ground Water Monitoring program represent water 

produced by a single well. All public-supply well samples 

were analyzed for total concentrations of a constituent 

(dissolved plus particulate).

Evaluation of the Effect of Land Cover and 

Population Characteristics on Water Quality

To evaluate the effects of nearby land cover and population on groundwater quality in 2009, a circle with a radius 

of 500 meters (m) (1,640 ft) was created around each of the 

16 domestic wells sampled in 2009 and the 7 public-supply 

wells considered in this report. Because the regional direction 

of groundwater flow was known near each well (Jagucki and 

Lesney, 1995), it was possible to further refine the land area 

most likely to affect the quality of water captured by each well 

by converting each circle into a single quarter-circle segment and rotating it toward the upgradient direction (fig. 13), 

as described by Ator and Denis (1997) and Button (2003). 

Land-cover data within the quarter circle were then extracted 

(appendix table 3–1), along with population data described 

below. Land-cover data were from the 2001 National Land 
22 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Table 4. Physical characteristics of public-supply well fields considered in this report and analyses available, Geauga County, Ohio, 

2000–2010.

[Ohio EPA, Ohio Environmental Protection Agency; Fm., Formation; Na, sodium; Cl, chloride; Fl, fluoride; SO4, sulfate; TDS, total dissolved solids; NH3, 

ammonia; NO3, nitrate; NO2, nitrite; As, arsenic; Cd, cadmium; Cr, chromium; Cu, copper; Fe, iron; Pb, lead; Mn, manganese; Se, selenium; Zn, zinc;VOCs, 

volatile organic compounds; —, not available; U, untreated water analyzed; T, treated water analyzed; U+T, both treated and untreated samples analyzed. 

Data compiled from Ohio Environmental Protection Agency’s (2010c) drinking water source assessment reports for each well, Ohio Environmental Protection Agency’s Ambient Groundwater Monitoring Program database (2010d) and Safe Water Information System database (2010e), and Ohio Department of 

Natural Resources water withdrawal registration program database (2010b). Approximate well locations are shown in fig. 12.]

Well 

identifier 

(for 

report 

purposes)

Name of 

public-supply 

well field

Township

Ohio 

EPA 

data 

source

Number 

of wells 

in 

wellfield

Number 

of 

wells 

sampled 

for this 

report 

unless 

noted 

otherwise 

Aquifer

Total 

pumping 

rate, in 

gallons 

per day

Open interval of 

sampled wells, 

in feet below 

land surface1

Top Bottom 

1 ASM 

International

Russell Ambient 

network

2 1 Pottsville 

Fm.

2,040 88 138 

2 Burton Village Burton Compliance 

data2

2 2 Pottsville 

Fm., glacial 

deposits

165,000 50–90 65–120 

3 Chardon City Munson Compliance 

data

6 6 Glacial 

deposits

646,080 105–144 — 

4 Christ Presbyterian 

Church

Chester Compliance 

data

1 1 Pottsville 

Fm. and 

Cuyahoga 

Group

620 — 130 

5 Lake Lucerne Bainbridge Compliance 

data

14 14 Berea 

Sandstone

145,280 25–55 80–305 

6 Middlefield 

Village

Middlefield Ambient 

network3

2 1 Glacial 

deposits

385,000 90 104 

7 Tanglewood 

Lake

Bainbridge Ambient 

network3

8 1 Cuyahoga 

Group

295,000 43 159 

1

The open interval is the uncased portion of the well, through which water from the aquifer(s) enters the well. A range of depths is shown for the top and 

bottom of the open interval if sampled water was a blend of water from more than one well.

2

Compliance data are analytical results submitted to Ohio EPA Division of Drinking and Ground Waters by Ohio public water systems and their certified 

laboratories to comply with legal monitoring requirements under the Safe Drinking Water Act. These data are stored in the Ohio EPA’s Safe Water Information 

System database. Samples may be either untreated or treated, and, with the exception of samples from Christ Presbyterian Church, represent a blend of water 

from multiple wells in the well field.

3

 Most chemical analyses considered for this well field are from Ohio EPA’s Ambient Groundwater Monitoring Network and are samples of untreated water 

from a single well. Compliance data were also obtained for this well field, but were only used when the samples from the Ambient Network well were not 

analyzed for a constituent of interest. When compliance data were used, the sample may be treated or untreated water and represents a blend of water from all 

wells in the well field. 
Methods of Study 23

Table 4. Physical characteristics of public-supply well fields considered in this report and analyses available, Geauga County, Ohio, 

2000–2010.—Continued

[Ohio EPA, Ohio Environmental Protection Agency; Fm., Formation; Na, sodium; Cl, chloride; Fl, fluoride; SO4, sulfate; TDS, total dissolved solids; NH3, 

ammonia; NO3, nitrate; NO2, nitrite; As, arsenic; Cd, cadmium; Cr, chromium; Cu, copper; Fe, iron; Pb, lead; Mn, manganese; Se, selenium; Zn, zinc;VOCs, 

volatile organic compounds; —, not available; U, untreated water analyzed; T, treated water analyzed; U+T, both treated and untreated samples analyzed. 

Data compiled from Ohio Environmental Protection Agency’s (2010c) drinking water source assessment reports for each well, Ohio Environmental Protection 

Agency’s Ambient Groundwater Monitoring Program database (2010d) and Safe Water Information System database (2010e), and Ohio Department of Natural 

Resources water withdrawal registration program database (2010b). Approximate well locations are shown in fig. 12.]

Well 

identifier 

(for 

report 

purposes)

Chemical analyses available, 2000–2010

pH Na Cl Fl SO4 TDS NH3 NO3 NO2 As Cd Cr Cu Fe Pb Mn Se Zn Pesticides VOCs

1 U U U U U U U U — U U U U U U U U U — U

2 — — — — — — — T4 T4 T4 — — — — — — — — T4 T4

3 — — — — — — — T4 T4 T4 — — — — — — — — T4 T4

4 — — — — — — — T T — — — — — — — — — — T

5 — U4 — U4 U4 U4 — T4 U4+T4 U4+T4 U4 U4 U4 U4 U4 U4 U4 — U4+T4 U4+T4

6 U U U U U4 U4 — T4 U4+T4 U+T4 U U U U U U U U U4+T4 U4+T4

7 U U U U U4 — — T4 U4+T4 U U U U U U U U U T4 U4+T4

4

The sample represents a blend of water from more than one well.
24 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Cover Database (Homer and others, 2007). The number of 

acres permitted for biosolids application (Ohio Environmental 

Protection Agency, 2010a) within each quarter circle also was 

documented, along with the number of producing oil and gas 

wells (Ohio Department of Natural Resources, 2008a).

To characterize the number of people within the upgradient quarter circle, a map of population distribution (fig. 5) was 

created as described below by using the 2001 National Land 

Cover Database and population from the 2000 census blocks 

(U.S. Census Bureau, 2009; Tele Atlas North America, Inc., 

2008). A weighting scheme was applied with the areas that 

corresponded to some land-cover classes, such as developed, 

being assigned a higher relative density than other areas, such 

as those characterized as water. The total count of people 

within a census block remained the same as the census-published data, but the estimated distribution of people within the 

census block was no longer arbitrary. This dasymetric mapping technique more accurately portrays the actual distribution 

of population within a census block than a mapping method 

that uses one population value for the entire area of the census 

block. 

The strength of the association between land use (2001) 

or population (2000) upgradient of a well and a constituent 

concentration in water from the well (in 2009 for domestic 

wells or 2000–2010 for public-supply wells) was measured 

by the nonparametric Spearman’s rho correlation coefficient. 

Correlation analysis of activities at land surface to quality of 

water from wells sampled for this study has some limitations: 

1. Not all sampled wells are likely to be affected by recent 

activities at land surface, because constituents applied 

at land surface will take longer to reach wells with 

open intervals at greater depths than those with shallower open intervals. Although tritium analyses from 

a previous study indicate that water from most wells 

tapping glacial deposits, the Pottsville Formation, and 

the Cuyahoga Group entered the groundwater system 

after 1953 (Jagucki and Darner, 2001)—and thus may be 

affected by land use after this time—tritium analyses of 

a limited number of samples from the Berea Sandstone 

indicate that water in this aquifer recharged prior to 

1953 (when population and percent developed land were 

much less than they were in the years 2000 and 2001). 

Furthermore, simulations of groundwater flow by Eberts 

and others (1990) estimated that water in the Berea 

Sandstone recharged the water table hundreds of years 

ago (fig. 2); thus, land-surface activities in 2001 will be 

unlikely to have influenced current (2009) water quality 

in wells tapping the Berea Sandstone. 

2. A large component of water reaching the deeper wells 

likely originated from farther away than 500 m and may 

be influenced by land use characteristics outside of the 

500-m quarter circle.

3. Groundwater withdrawn from a well likely is a mixture 

of water that recharged during a range of years rather 

than during a single year. For an ideal comparison of 

land cover to water quality, computer simulations of 

groundwater flow would be used to track groundwater 

movement in reverse and estimate when and where water 

that is currently in the open interval of a well recharged 

the groundwater system. Next, land cover in the recharge 

area during the applicable year(s) would be compared to 

current water quality. However, such detailed tracking 

of groundwater flow and land cover were beyond the 

scope of this project. Because a comparison of landcover changes from 1992 to 2001 (fig. 6, this report) and 

from 1975 to 1996 (table 2, Jagucki and Darner, 2001) 

indicates that percentages of major land-cover categories 

have not changed dramatically since 1975, a simplified 

comparison of land cover during a single year to recent 

water quality is useful for this study area.

EXPLANATION

Potentiometric contour

1150

1100

1150

Quarter 1050

circle

rotated

Well 

location 500 meters

Well 

location

A B C

Quarter circle

oriented 

upgradient

Well 

location

Figure 13. Method used to determine area for categorizing upgradient land use and population. A 500-meter radius was generated 

around each well (A), converted into a quarter circle, and rotated (B) to orient it to an upgradient groundwater-flow as determined by 

Jagucki and Lesney (1995). Land use and population density data within the quarter circle were then extracted (C). Figure modified from 

Button (2003).
Methods of Study 25

Thus, analyses of correlation of land cover and population to groundwater quality must be interpreted with caution. 

Although a lack of a correlation between 2001 land cover 

and 2009 constituent concentrations does not mean that such 

activities will never affect the quality of water in downgradient wells in the future, a positive correlation can provide 

useful insights.

Statistical Analysis to Evaluate Changes Over 

Time

Changes in water quality since 1978 were evaluated by 

using data collected by the USGS for 16 wells sampled across 

the county in 2009 (table 3) and using another 100 samples 

collected during previous studies from these 16 wells plus 49 

additional wells (appendix table 4–1). Only data collected by 

the USGS were considered in this analysis to so that sources 

of variability introduced by sample collection, handling, and 

laboratory analysis would be minimized. USGS personnel 

used similar sample collection methods during each year, and 

all samples were analyzed at one lab—the USGS National 

Water Quality Laboratory—with the exception of nutrients, 

which were analyzed by Heidelberg University (Tiffin, Ohio) 

in 1999. Even so, analytical procedures, instruments, and laboratory reporting levels within the USGS National Water Quality Laboratory sometimes changed between 1978 and 2009.

All groundwater-quality data were retrieved from the 

USGS National Water Information System (NWIS) database. 

Data were available on a countywide basis for the years 1978, 

1980, 1986, 1999, and 2009 (appendix table 4–1). Rarely, the 

same well had been sampled twice in one year; in these cases, 

a single sample for each year (one collected in spring or summer) was used in the statistical analysis. All samples represent 

water from the aquifer prior to any type of treatment. 

For all statistical analyses of changes over time, concentrations of a given constituent were censored to a common 

reporting level equal to the highest laboratory reporting level 

used for that constituent during 1978–2009. (The laboratory 

reporting level for a given analyte and laboratory can change 

as often as annually.) All values reported as less than the common reporting level were assigned the same value that was 

less than all reported concentrations, so that ranks of values 

below the highest reporting level would be tied, yet lower than 

the rank for the lowest detected measurement (Helsel, 2005). 

For all statistical tests, a p-value of less than 0.05 was deemed 

to be statistically significant. 

Changes over time were evaluated one of three ways, 

depending on whether or not the data were from a variable set 

of wells or a single well network that was able to be resampled 

in subsequent years, and on the number of nondetections 

(“nondetects”) for a given constituent: 

1. For constituents that were analyzed for in samples 

collected from the same well during successive years 

(1986 and 1999, and [or] 1999 and 2009), pairs of data 

from repeated analyses in a given well were compared 

by using a Wilcoxon signed-rank test. These “paired” 

data provide snapshots of water quality at the same well 

several years apart. The well-selection process in 1999 

and 2009 focused on maximizing the number of wells 

that were resampled so that this statistical test could be 

used. The Wilcoxon signed-rank test looks at the magnitude of differences between the pair of concentration 

measurements at each resampled well and determines 

whether the median difference of all paired measurements is significantly different from zero (Helsel, 2005). 

The advantage of considering only resampled wells is 

that the variation or “background noise” in the dataset is 

minimized. (For example, when a different set of wells 

is sampled each year, variation caused by sampling 

wells of different depths in different years can obfuscate 

the effect being studied (changes with time) (Helsel, 

2005; Helsel and Hirsch, 2002). A disadvantage of this 

test method is that data from all aquifers were grouped 

together for the statistical test; because of the small 

sample size (a total of 16 paired samples for 1999 and 

2009), data could not be separated out by aquifer. Grouping data from multiple aquifers can hinder detection 

of differences in concentration between years if such 

differences occur only in a single aquifer. The Wilcoxon 

signed-rank test was used for constituents for which at 

least 50 percent of the samples had detectable concentrations. A two-sided test was done to test for either an 

increase or decrease in concentration between years.

2. For constituents that were analyzed for during three or 

more years between 1978 and 2009, changes over time 

were evaluated by using a nonparametric Spearman’s 

rho correlation test. In general, a variable set of wells 

was sampled each year (because resampling of the same 

wells often was not possible). Spearman’s rho measures 

the strength of the association between sampling year 

and constituent concentration (or how likely it is that 

concentration consistently increases or decreases as time 

increases). This method was used for constituents that 

had detectable concentrations in at least 50 percent of 

the samples (and thus are considered to be frequently 

detected constituents). The advantages of this test are 

that temporal trends in each individual aquifer can be 

evaluated and that data from the entire period of record 

can be utilized. The disadvantage is that variation or 

“background noise “ can be introduced by sampling a 

different set of wells each year that may obfuscate the 

effect being studied (changes with time) (Helsel, 2005).
26 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

3. For constituents that were analyzed during two or more 

years but had a fewer than 50 percent detections (total 

coliform bacteria, nitrate, orthophosphate, and sulfide), 

graphical rather than statistical methods of evaluating 

temporal changes in water quality were used because of 

confounding factors that could interfere with an accurate 

calculation of statistical significance for these constituents. Confounding factors include median concentrations 

that are below the reporting limit in most years; constituents that are present only in certain aquifers, geochemical environments, elevations, and (or) depths so that 

well selection can greatly affect results; or the chlorination of wells between sampling rounds, which may 

affect bacteria concentrations. For the four constituents, 

detection frequency was graphically compared during 

successive years. (Detection frequency is the percentage 

of data above the common censored level for a constituent during a given year; that is, the number of detections 

divided by the total number of samples for a year.) In 

addition, concentrations of these four constituents were 

compared by use of bar charts for samples collected in 

successive years from the same well. 

The use of quality-assurance/quality-control data to 

assess the effect of sample reproducibility and temporal 

laboratory variability on the statistical evaluation of changes 

in constituent concentrations over time is described in 

appendix 2. 

Evaluation of Oxidation-Reduction Conditions in 

the Subsurface

Microbial-induced chemical reactions in the subsurface 

can control the concentration of several naturally occurring 

constituents in groundwater as well as how persistent some 

manmade contaminants will be in the subsurface. Based on the 

measured concentration of dissolved oxygen, nitrate, manganese, iron, and sulfate in 116 samples collected by the USGS 

during 1978–2009, the oxidation-reduction—or redox—condition of each sample was categorized according to criteria 

defined by Jurgens and others (2009). Redox categories 

used in this report are oxic, suboxic, and the following types 

of reducing conditions: manganese reducing, iron and (or) 

sulfate reducing (also referred to as “strongly reducing”), or 

methanogenic. 

Groundwater Quality

Groundwater-quality data were evaluated to answer the 

following questions: (1) Are there any constituents in Geauga 

County groundwater in 2009 that may adversely affect human 

health or aesthetics of drinking water? (2) How do constituent concentrations compare to those found elsewhere in Ohio 

and in the Nation, as reported in recent studies (DeSimone and 

others, 2009; Francy and others, 2004; Gilliom and others, 

2006; Ohio Environmental Protection Agency, 2012b; Zogorski and others, 2006)? (3) How frequently is methane detected 

in water wells? (4) Have concentrations of water-quality constituents changed over time, since samples were first collected 

by the USGS in 1978? (5) What factors affect constituent 

concentrations and occurrence, including human activities at 

land surface, aquifer tapped by a well, and well construction? 

Status in 2009 

The status of groundwater in the county, and its potential 

effect on human health as a source water for drinking, was 

assessed on the basis of analyses of water from 16 domestic 

wells and wells serving very small public-supplies (table 3) 

sampled by USGS personnel in 2009 (hereafter collectively 

referred to as “domestic wells”), as well as Ohio EPA water 

quality-data for 7 public-supply well fields (table 4), compiled 

for the period 2000–2010 unless otherwise noted. Publicsupply-well data were included to provide additional information about groundwater quality in the more populated areas of 

the county, particularly regarding concentrations of manmade 

contaminants such as pesticides and VOCs. By focusing 

as much as possible on untreated groundwater (samples of 

“source water”), the assessment of groundwater described 

below complements monitoring done by water utilities that 

typically focus on the chemistry of drinking water delivered 

to the public. Safety of drinking water at the tap is reported by 

water utilities annually in consumer confidence reports that are 

issued to customers. 

Comparison to Health-Based Benchmarks

Concentrations of water-quality constituents measured 

in 2009 were compared to benchmarks for human health, if 

established (appendix tables 4–1and 4–2), and to aesthetic 

standards to determine the suitability of groundwater for 

drinking. Most health-based benchmarks were derived from 

drinking-water standards and guidelines established by the 

USEPA (2006 and 2009) (see sidebar). For public-supply wells 

or well fields serving 25 or more people, benchmarks based 

on MCLs are legally enforceable by the USEPA. However, 

domestic wells in Geauga County are only required to meet 

the health-based benchmarks for total coliform, Escherichia 

coli (E. coli) bacteria, and other fecal indicator microorganisms (Ohio Department of Health, 2011a). The total coliform 

benchmark is established by the Ohio Administrative Code 

and enforced by the Geauga County Health District (2010a). 

Testing for nitrate, total coliform, and E. coli bacteria is 

required on untreated water from a newly drilled or altered 

domestic well, or for a well located on a property that is being 

sold or refinanced (Ohio Department of Health, 2011a; Geauga 

County Health District, 2010a). 
Groundwater Quality 27

Forty-one of the 92 properties and constituents analyzed for in water samples from domestic wells in 2009 had 

human-health benchmarks to which analytical results could 

be compared, as listed in appendix tables 4–1 and 4–2. Four 

of these benchmarks—for arsenic, total coliform bacteria, 

fecal coliform bacteria, and sodium—were exceeded in some 

Human-Health Benchmarks for Contaminants in Groundwater

Most of the benchmarks for assessing the potential for chemical constituents in water to affect human health were 

derived from five types of drinking-water standards and guidelines developed by USEPA’s Office of Water (U.S. 

Environmental Protection Agency, 2006, 2009):

Maximum Contaminant Level (MCL)—The maximum permissible concentration of a contaminant in water that 

is delivered to any user of a public water system. This is a legally enforceable standard issued by USEPA under the 

Safe Drinking Water Act and established on the basis of health effects and factors such as the availability of affordable analytical and treatment technologies.

Lifetime Health Advisory (HA-L)—The concentration of a chemical in drinking water at or below which there 

is not expected to be any adverse, noncarcinogenic effects over a lifetime of exposure. A health advisory is not 

a legally enforceable Federal standard but serves as technical guidance to assist Federal, State, Tribal, and local 

officials. The HA-L is based on toxicity (dose-response) information for the chemical. It assumes lifetime consumption of 2 liters (L) of water per day by a 70-kilogram (154-pound) adult and that 20 percent of total exposure to the 

contaminant comes from drinking water whereas 80 percent comes from other sources.

10−6 Cancer Risk Concentration (HA-C)—The concentration of a chemical in drinking water corresponding to an 

excess estimated lifetime cancer risk of 1 in 1 million (10−6). (The excess cancer risk means that it is in addition to 

any cancer risk borne by a person not exposed to the chemical of interest.) HA-C values are calculated from the estimated cancer potency, which is derived using a conservative (protective) model of carcinogenesis, so that the cancer 

risk is an upper-limit estimate. USEPA’s policy is to accept measures adopted by States to limit cancer risk to the 

range of 10−6 to 10−4, meaning that 1 in 1 million to 1 in 10,000 people will get cancer by consuming a chemical in 

drinking water at the specified level (U.S. Environmental Protection Agency, 1992). The concentration corresponding to a cancer risk of 10−6 was used as the benchmark for the purposes of this report.

Action Level—The level of copper or lead in water at or above which additional steps are required to reduce the 

contaminant concentration (such as reducing the corrosiveness of the water). For regulatory purposes, the action 

level is applied only to tapwater samples of public-supply wells and only if more than 10 percent of the samples 

exceed the action level.

Drinking Water Advisory (DWA)—The concentration of a contaminant in water at or below which there are likely 

to be no adverse effects on health and aesthetics. A greater concentration may have adverse effects, with the likelihood increasing as the concentration increases. DWAs are not legally enforceable. The DWA for sodium applies 

only to people on a 500 milligram per day restricted sodium diet. 

If available, the MCL was used as the human-health benchmark for a given water-quality constituent. For constituents with no MCL, the lower of the HA-L and the HA-C was used. The Action Level was used for the constituents 

lead and copper. The DWA was used if no MCL, HA-L, or HA-C exists and is of lesser concern. 

(Sidebar modified from Gilliom and others, 2006, p. 91.)

domestic well samples (table 5). Some samples from publicsupply wells exceeded human-health benchmarks for arsenic, 

cadmium, lead, and sodium. Notable results are described 

below. Factors that affect where these constituents of concern 

are likely to occur are discussed in a subsequent section of the 

report.
28 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Table 5. Exceedances of health-based benchmarks and aesthetically based standards in water quality of 16 domestic wells (2009) 

and 7 public-supply well fields (2000–2010) in Geauga County, Ohio.—Continued

[μg/L, micrograms per liter; mg/L, milligrams per liter; mL, milliliter; MCL, Maximum Contaminant Level; OAC, Ohio Administrative Code; DWA, 

Drinking Water Advisory; SMCL, Secondary Maximum Contaminant Level; NA, not available; >, greater than. Red text denotes samples that exceeded the 

water-quality benchmark. Human-health benchmarks and health effects are derived from standards and guidelines established by the U.S. Environmental 

Protection Agency (2003, 2006, and 2009) for concentrations of contaminants in drinking water, unless otherwise noted. Common sources of constituents 

are from Hem (1989) and the U.S. Environmental Protection Agency (2009)]

Benchmark 

type

Constituent Water quality

benchmark1

Number of wells 

exceeding drinking 

water benchmark 

out of total number 

of wells or well 

fields sampled

Common sources

of constituent

Potential effect of exceedance 

on water use or health 

(with long-term exposure)

Domestic PublicSupply 

Health-based 

Arsenic MCL = 

10 μg/L

2 of 16 2 of 6 Aquifer sediments and 

rocks

Skin damage or problems with 

circulatory systems, and may increase 

risk of cancer.

Total 

coliform 

bacteria

OAC = 

4 total 

coliform 

colonies/

100 mL2

2 of 16 NA Soil or intestines of 

warmblooded animals

Indicates the possibility, but not the 

certainty, that the water is contaminated with human or animal fecal 

wastes. Pathogens in wastes may 

cause diarrhea, cramps, nausea, headaches, or other symptoms.

Fecal 

coliform 

bacteria

MCL = 

no fecal 

coliforms

1 of 14 NA Soil or intestines of 

warmblooded animals

Indicates the possibility, but not the certainty, that the water is contaminated 

with human or animal fecal wastes. 

Pathogens in wastes may cause diarrhea, cramps, nausea, headaches, or 

other symptoms.

Cadmium MCL = 

5 μg/L

0 of 4 1 of 4 Corrosion of galvanized 

pipes; aquifer rocks and 

sediments; industrial 

sources

Kidney damage.

Lead Action 

Level = 

15μg/L 

0 of 4 1 of 4 Corrosion of household 

plumbing; aquifer rocks 

and sediments

May cause delays in physical and 

mental development of infants and 

children. May cause kidney problems 

or high blood pressure in adults.

Sodium DWA = 

20 mg/L

6 of 16 4 of 4 Aquifer rocks; road salt; 

septic leachate; water 

softener regeneration

May increase blood pressure 

(hypertension) in at-risk individuals.

1

 For definitions of health-based water quality benchmarks, see sidebar, p. 27.

2

 OhioAdministrative Code (OAC) standard for a 100-mL water sample from a private water system in Ohio with 25 or more feet of casing (Ohio Department of Health, 2012). The Geauga County Health District requires that this standard be met during compulsory testing of 

untreated water from a newly constructed well, a well that has had a major change to the construction or water system configuration, or a well on 

a property that has been sold or refinanced (Geauga County Health District, 2010). 
Groundwater Quality 29

Table 5. Exceedances of health-based benchmarks and aesthetically based standards in water quality of 16 domestic wells (2009) 

and 7 public-supply well fields (2000–2010) in Geauga County, Ohio.—Continued

[μg/L, micrograms per liter; mg/L, milligrams per liter; mL, milliliter; MCL, Maximum Contaminant Level; OAC, Ohio Administrative Code; DWA, 

Drinking Water Advisory; SMCL, Secondary Maximum Contaminant Level; NA, not available; >, greater than. Red text denotes samples that exceeded the 

water-quality benchmark. Human-health benchmarks and health effects are derived from standards and guidelines established by the U.S. Environmental 

Protection Agency (2003, 2006, and 2009) for concentrations of contaminants in drinking water, unless otherwise noted. Common sources of constituents 

are from Hem (1989) and the U.S. Environmental Protection Agency (2009)]

Benchmark 

type

Constituent Water quality

benchmark1

Number of wells 

exceeding drinking 

water benchmark 

out of total number 

of wells or well 

fields sampled

Common sources

of constituent

Potential effect of exceedance 

on water use or health 

(with long-term exposure)

Domestic PublicSupply 

Aesthetically based

Iron SMCL3= 

300 μg/L

10 of 16 3 of 4 Aquifer sediments and 

rocks

Staining of fixtures, utensils, and 

laundry. Higher concentrations form 

reddish-brown sediment and waterline deposits and may give the water 

a metallic taste.

Manganese SMCL= 

50 μg/L

10 of 16 3 of 4 Aquifer sediments and 

rocks

Dark-brown or black staining of 

fixtures, utensils, and laundry.

Total 

dissolved 

solids

SMCL= 

500 mg/L

2 of 16 2 of 3 Dissolution of aquifer 

minerals; road salt; 

brines; septic leachate

Concentrations > 1,000 mg/L may cause 

objectionable tastes and laxative 

effects. Also my cause foaming or 

may corrode some metals.

Chloride SMCL= 

250 mg/L

0 of 16 1 of 3 Dissolution of aquifer 

minerals; road salt; 

brines; septic leachate

At concentrations > 250 to 400 mg/L, 

imparts a salty taste to water depending on individual tolerance. High 

concentrations are corrosive to most 

metals.

pH SMCL = 

6.5-8.5

1 of 16 1 of 3 Controlled by chemical 

reactions that produce 

or consume hydrogen 

ions in water, such as 

the reaction of dissolved carbon dioxide 

gas with water, mineral 

dissolution reactions, 

and oxidation reactions

Values outside the recommended range 

of 6.5 to 8.5 may be corrosive to 

metal well casings and pipes. A pH 

below 6.5 can generate health-related 

problems by dissolving small quantities of trace metals such as lead, 

especially in a house built before lead 

solder was banned in 1987.

3

 Secondary Maximum Contaminant Limit (SMCL) is the concentration of a contaminant in drinking water above which cosmetic effects 

(such as skin or tooth discoloration) or aesthetic effects (such as taste, odor, or color) may occur. The Environmental Protection Agency recommends SMCLs to water systems but does not require them to comply.
30 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Arsenic 

Prior to 2009, arsenic concentrations in groundwater 

samples from domestic wells had not been widely measured 

in Geauga County. (Seven domestic and three public-supply 

wells had been analyzed for arsenic by the USGS in 1978 

and 1980.) The impetus to include arsenic in the most recent 

USGS sampling round was the lowering of the MCL from 50 

mg/L to 10 mg/L on January 1, 2006, for all community and 

non-transient water systems (Ohio Environmental Protection 

Agency, 2006b). The MCL was lowered because a review by 

the National Academy of Sciences of worldwide studies of 

arsenic health effects concluded that the risk level at 50 μg/L 

was higher than previously thought (Ohio Environmental 

Protection Agency, 2006b). 

Arsenic occurs naturally (but is distributed unevenly) in 

some sediments and rocks, and it can dissolve into groundwater under certain geochemical conditions. Regular ingestion 

of arsenic in water at concentrations exceeding the MCL of 

10 mg/L can increase the risk of long-term or chronic health 

problems such as lung, bladder, skin, kidney, nasal, liver, and 

prostate cancer. Low levels of arsenic can also cause skin 

damage or problems with circulatory, pulmonary, immune, 

nervous, and endocrine systems (Ohio Environmental Protection Agency, 2006b; http://arsenicinohiogroundwater.info/). 

Arsenic in water has no smell or taste, so water must be tested 

to determine whether the arsenic concentration exceeds the 

MCL.

Domestic wells.—Concentrations of arsenic in the two 

wells exceeding the MCL (table 5) were 12.9 mg/L (GE-202) 

and 13.2 mg/L (GE-108) (locations shown in fig. 12). Wells 

GE-202 and GE-108 draw water from the Pottsville Formation 

and the glacial deposits, respectively. The median concentration of arsenic in all sampled domestic wells was 1.1 mg/L. 

Descriptions and comparisons of household water treatment 

options to remove arsenic are available at http://arsenicinohiogroundwater.info/. Arsenic-specific treatment is needed 

because boiling water will not remove arsenic; neither will 

chlorine (bleach) disinfection (New Hampshire Department 

of Environmental Services, 2006), common household water 

softeners, sediment filters, or activated carbon filters (http://

arsenicinohiogroundwater.info/).

Public-supply well fields.—Arsenic data were available 

for six of the seven public-supply well fields examined for 

this study. Both untreated and treated water concentrations 

were considered. Arsenic concentrations exceeding the MCL 

were recorded in two of these well fields (table 5) over the last 

decade, with maximum concentrations of 17 μg/L in Chardon 

City (well 3, fig. 12) and 20 μg/L in Middlefield Village (well 

6, fig. 12). However, arsenic concentrations were reduced 

to levels below the MCL when these two community water 

systems began using macrolite filtration to treat their water for 

arsenic in mid-2008 (Dan Sellito, 2011, City of Chardon Water 

and Wastewater, written commun., 2011; Michael Cipolla, 

Village of Middlefield Water Treatment Department, oral 

commun., 2011). 

Total and Fecal Coliform Bacteria

Total coliform bacteria, fecal coliform bacteria, and a 

species of fecal coliform bacteria called E. coli are considered 

to be indicator organisms; their presence does not constitute 

a health hazard in itself but indicates a possibility (but not a 

certainty) that disease-causing organisms also may be present 

in the water because of contamination from human or other 

animal waste. The human-health benchmark for total coliform 

(table 5, 4 colonies per 100 milliliters [mL] of water) applies 

to domestic wells with 25 ft or more of casing. Wells with less 

than 25 ft of casing that use continuous disinfection should 

contain no total coliforms (Ohio Department of Health, 2012). 

Domestic wells.—Total coliform bacteria were detected 

in 5 of 16 domestic wells sampled in 2009 (over 31 percent) 

but were present at concentrations exceeding the health 

benchmark of 4 colonies per 100 mL of water in only 2 of 

these wells (12.5 percent ) (table 5 and appendix table 4–1). 

Because total coliform bacteria can also occur naturally in the 

soil and in plants, their presence does not necessarily indicate 

a sewage-contamination problem or imminent health risk. 

However, the Ohio Department of Health suggests that wells 

containing more than 4 total coliform bacteria per 100 mL be 

professionally cleaned, chlorinated, and retested, because this 

can indicate poor well construction, a buildup of bacterial and 

mineral slimes in the well, or the presence of holes in the well 

casing due to aging of the well (Ohio Department of Health, 

2011b, 2012). Water from well GE-141, in which the highest total coliform concentration was detected (49 colonies per 

100 mL of water), also contained detectable fecal coliform 

(estimated at 1 colony per 100 mL of water), suggesting a 

possible health risk to people consuming this water. No E. coli

bacteria, which originate only in the intestines of humans or 

other warmblooded animals, were found in any of the 16 wells 

tested in the county.

Public-supply well fields.—The only available bacteria 

samples from public-supply well fields were collected after 

treatment (and treatment includes chlorination in six of the 

seven well fields). Thus, bacteria concentrations from publicsupply well fields were not evaluated because they would not 

be representative of water in the aquifer.

Trace Metals

Domestic wells.—Groundwater samples from four 

domestic wells (one in each aquifer) were analyzed for the 

trace metals cadmium, chromium, copper, lead, selenium, 

and zinc. Only lead and zinc were detected, but not at concentrations that exceeded health-based standards specified in 

appendix table 4–1. 

Public-supply well fields.—Only untreated water from 

public-supply well fields was evaluated in comparison to 

health-based standards for the trace metals listed above. 

Untreated samples were available from four of the seven well 

fields (table 4). Cadmium exceeded the MCL (5 μg/L) in 

one of 13 samples from the Tanglewood Lake public-supply 
Groundwater Quality 31

(well 7, fig. 12, maximum concentration of 18.8 μg/L). The 

most likely cadmium source is corrosion of galvanized pipes. 

Two of 21 samples from ASM International public-supply 

(well 1, fig. 12) exceeded the lead action level of 15 μg/L 

(maximum concentration of 29.5 μg/L), which represents an 

exceedance frequency of 9.5 percent for samples collected 

from a single well during 2000–2010. Although this comparison of untreated water to the lead action level provides some 

context for evaluating the healthfullness of aquifer water 

withdrawn by the public-supply wells, in reality the legal 

enforcement of the lead drinking-water standard evaluates 

treated water collected not from a single supply well but from 

customers’ taps. Because most lead gets into drinking water 

after the water leaves the local well or treatment plant and 

comes into contact with plumbing materials containing lead 

(which were commonly used until 1986), water suppliers must 

employ a treatment technique to reduce the corrosiveness of 

their water if more than 10 percent of samples of treated water 

from customers’ taps collected during a 6-month, annual, or 

triennial sampling exceed the lead action level (U.S. Code of 

Federal Regulations, 1987). 

Sodium 

Domestic wells.—Sodium concentrations exceeded the 

human-health benchmark of 20 mg/L (for persons with medical reasons for moderating dietary intakes of sodium) in 6 of 

16 domestic wells sampled (38 percent). The maximum concentration measured was 86.9 mg/L at well GE-147 (appendix 

table 4–1). Note that all water samples were collected prior to 

passing through the home water treatment system. Homeowners who soften their water using ion exchange methods may be 

adding even more sodium content to their tapwater, because 

calcium, magnesium, iron, and manganese ions in groundwater replace sodium ions on the adsorption media, causing 

sodium to be released into the tapwater during the softening 

process (Driscoll, 1986). 

Public-supply well fields.—Sodium concentrations 

exceeding, at least periodically, the human-health benchmark 

for people on a low-sodium diet (20 mg/L) were measured 

in untreated water from the four public-supply well fields for 

which untreated sodium data were available. The maximum 

measured concentration was 320 mg/L in a sample from Lake 

Lucerne public supply (well 5, fig. 12).

Manganese

Manganese occurs naturally in aquifer sediments and 

rocks and is dissolved into groundwater under certain geochemical conditions. Manganese at concentrations greater than 

300 mg/L can cause undesirable neurological effects (Agency 

for Toxic Substances and Disease Registry, 2008). 

Domestic wells.—No groundwater samples collected in 

2009 exceeded the health-based benchmark (HA-L) of 300 

mg/L for manganese, so manganese is not listed as a constituent of concern in table 5. Historical data for 65 domestic wells 

sampled by the USGS since 1978, however, includes 5 wells 

(about 8 percent) that have exceeded 300 mg/L of manganese, 

with a maximum concentration of 1,200 μg/L. 

Public-supply well fields.—Manganese analyses of 

untreated water (2000–2010) were available for four of the 

seven public supply well fields. No samples exceeded the 

health-based benchmark for manganese.

Pesticides 

Agricultural pesticides were a focus of this study because 

the nationwide use of pesticides on agricultural lands in 2001 

was about three times that of nonagricultural use (Gilliom and 

others, 2006). The 52 pesticides3 analyzed for in water from 

domestic wells (appendix table 4–2) include many of the herbicides (used to kill or control weeds) and insecticides (used 

to eradicate insects) that are most heavily used for agricultural 

applications in the Nation. Additionally, the pesticides analyzed for include four of the five pesticides (dieldrin, donoseb, 

atrazine, lindane, and diazinon) found to exceed human-health 

benchmarks in groundwater nationwide (Gilliom and others, 

2006). Forty-six of the analyzed pesticides have a humanhealth benchmark (appendix table 4–2).

Domestic wells.—Of the 52 pesticides analyzed for, 

only the herbicide atrazine was detected at a concentration 

above the laboratory reporting level (appendix table 4–2), 

and it was found in only one well (GE-341, which taps the 

Cuyahoga Group aquifer, table 3). Atrazine was detected 

at a concentration of 0.0073 μg/L, which is far below 

the MCL of 3 μg/L. Water from GE-341 also contained 

a trace amount of the atrazine degradation product CIAT 

(2-chloro-4-isopropylamino-6-amino-s-triazine). 

Public-supply well fields.—Very few analyses of pesticides in untreated water from the seven public-supply well 

fields were available for the period 2000–2010. However, 

the authors considered compliance analyses of pesticides in 

treated water from the supply wells during this period to be 

representative of water in the aquifers because conventional 

treatment methods (such as are used at these wells) do little 

to remove mobile pesticides (U.S. Environmental Protection Agency, 2001). Water samples from Lake Lucerne and 

Tanglewood Lake public-supply were analyzed for several 

pesticides for which health-based benchmarks are established: 2,4-D, alachlor, atrazine, carbofuran, diquat, endothall, 

glyphosate, metolachlor, metribuzin, oxamyl, picloram, and 

simazine. None of these pesticides were detected. Similarly, 

samples from the Burton Village, Middlefield Village, and 

City of Chardon public supply well fields were analyzed for 

the pesticides alachlor, atrazine, and simazine, which were not 

detected. Reporting levels for these analyses were at least an 

order of magnitude less than the health-based benchmark for 

each pesticide.

3

 The pesticide names used in this report refer to the active ingredient, 

rather than the product name, because multiple products can have the same 

active ingredient (Milne, 1995).
32 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Volatile Organic Compounds

VOCs are manmade organic compounds used in products 

such as fuels, refrigerants, and industrial and dry-cleaning 

solvents. VOCs that were analyzed for in samples collected 

from domestic wells in 1999 (Jagucki and Darner, 2001) and 

in samples from the seven public-supply wells (1995–2009) 

are listed in appendix table 4–3. This list includes most of the 

VOCs that were detected during investigations of localized 

contamination of groundwater in Geauga County (fig. 11). 

Domestic wells.—USGS personnel did not sample any 

domestic wells for VOCs in 2009. However, 31 groundwater 

samples collected in 1999 were analyzed for benzene, TCE, 

toluene, PCE, and xylene (Jagucki and Darner, 2001, p. 58), 

with no detections (appendix table 4–3). 

Public-supply well fields.—VOCs were analyzed for in 

samples from the public-supply well fields on at least three 

separate dates from 1995 through 2009 (appendix table 4–3). 

Not all wells were analyzed at the same frequency. VOCs were 

analyzed for most often (9 times) at ASM International publicsupply (well 1, fig. 12). Analyses of both untreated and treated 

water are reported in table 4–3 and discussed below, because 

none of the seven public-supply wells examined for this study 

employ activated carbon, reverse osmosis, or air stripping 

treatment that would remove VOCs (New Jersey Department 

of Health and Senior Services, 1997; New Mexico Environment Department, 2008; Vermont Department of Health, 

2011). The Burton Village public-supply well does, however, 

treat for iron by aeration, which could volatilize VOCs that are 

present in groundwater. VOCs may also be partially volatilized by high-capacity pumps used in public-supply wells; as a 

result, analyzed concentrations should be considered minimum 

values. 

Of the almost 100 VOCs analyzed for in samples from 

the 7 public-supply well fields (appendix table 4–3), only 

chlorination byproducts (denoted by orange-highlighted text) 

were detected, with a single exception. Chlorination byproducts—various trihalomethanes and haloacetic acids—are not 

naturally present in groundwater. These compounds form 

when chlorine added to disinfect water combines with organic 

matter naturally present in the groundwater. This is exemplified by the water from Middlefield Village public supply—

untreated water samples contained no chlorination byproducts, but treated water did. Although it is not surprising that 

chlorination byproducts were found in treated water produced 

by most public-supply well fields, the presence of chlorination 

byproducts in untreated water from the Lake Lucerne publicsupply (the only well field besides Middlefield for which both 

untreated and treated water analyses were available) suggests 

that these VOCs are present in the aquifer at this location. 

Likely sources include the infiltration of chlorinated water 

to the subsurface through leakage from distribution pipes or 

watering of lawns. Maximum concentrations of total haloacetic acids and total trihalomethanes in both untreated and 

treated water from the studied public-supply wells did not 

exceed the human-health benchmarks (MCLs) for these compounds (60 μg/L and 80 μg/L, respectively). 

Total xylenes (a solvent that is a component of gasoline) 

was the only VOC detected in any of the studied publicsupply wells that was not a chlorination byproduct. Two of 

34 samples of treated water from the Lake Lucerne well field 

contained total xylenes at a concentration of 1.5 μg/L. This 

concentration is considerably less than the human-health 

benchmark of 10 mg/L. Both samples with detections were 

collected on the same day in 2008 from different locations in 

the system. No further detections occurred at this well field 

through 2010.

Comparison to Aesthetically Based Standards

In addition to drinking-water standards based on humanhealth benchmarks, standards called Secondary Maximum 

Contaminant Levels (SMCLs) were developed on the basis 

of constituent concentrations that affect taste, odor, staining of fixtures and laundry and sometimes skin and tooth 

color (U.S. Environmental Protection Agency, 2009). USEPA 

recommends that public water systems meet SMCLs but does 

not legally enforce these guidelines. Analytical results from 

domestic wells sampled in 2009 and from the seven publicsupply wells (untreated water only, 2000–2010) were compared to SMCLs (table 5). 

Iron and manganese were the constituents that most 

affected the aesthetics of groundwater used for drinking and 

household purposes in Geauga County. Among the wells with 

available data, 62 percent of the domestic well samples and 

75 percent of the public-supply well samples exceeded the 

SMCL for both iron (300 μg/L) and manganese (50 μg/L) 

(table 5). SMCLs for fluoride, sulfate, copper, and zinc were 

not exceeded in water from any sampled domestic well or 

public-supply well field.

Although hydrogen sulfide has no established healthbased or aesthetically based standards for drinking water, 

elevated concentrations of this constituent can adversely affect 

the odor of groundwater. Additionally, hydrogen sulfide gas 

can cause corrosion to metals commonly used in well casing 

and pump components, and it can cause yellow or black stains 

on bathroom fixtures (National Ground Water Association, 

2013). Water samples from 16 domestic wells were analyzed 

for total sulfide, which can be in the form of hydrogen sulfide 

gas or can precipitate out of groundwater as a finely disseminated, black iron sulfide mineral. Total sulfide was detected 

at concentrations greater than 0.005 mg/L in water from 8 (50 

percent) of the domestic wells. The maximum concentration 

measured was 0.124 mg/L. A hydrogen sulfide odor was noted 

by USGS personnel in seven of the eight samples containing 

total sulfide, indicating that some of the sulfide is in the form 

of hydrogen sulfide gas. Total sulfide data were not available 

for the public-supply well fields considered in this study.
Groundwater Quality 33

Comparison of Findings to State and National 

Studies of Water Quality 

To determine how the quality of groundwater from 

16 domestic wells in Geauga County in 2009 compares to 

groundwater quality elsewhere, exceedance frequencies of 

health-based benchmarks or detection frequencies of selected 

constituents in Geauga County were compared to those found 

statewide and nationally (fig. 14). Ideally, all datasets compared would consist of samples from domestic wells (because 

public-supply wells capture water originating over a larger 

area than domestic wells); however, domestic well data were 

not available on a statewide basis. Instead, statewide data 

consist of water-quality analyses from Ohio EPA’s Ambient 

Groundwater Quality Monitoring Program (Ohio Environmental Protection Agency, 2012b). This State program monitors 

untreated water from public-supply wells tapping the major 

aquifer systems of Ohio, with the goal of measuring long-term 

changes in water quality. Unless otherwise noted, the State 

exceedance frequencies described below are the percentages of wells sampled for which the mean concentration of 

all samples analyzed during 2001–2010 exceeded the MCL. 

Nationwide data used in this study, with the exception of pesticide and VOC data, are from a USGS study of untreated water 

from domestic wells in 48 states from 1991 through 2004 

(DeSimone and others, 2009). 

Arsenic.—Arsenic occurred at concentrations exceeding the MCL at about the same frequency in Geauga County 

groundwater as it did elsewhere in Ohio but more frequently 

than across the Nation as a whole (fig. 14A). Over half of the 

arsenic exceedances in Ohio occurred in water from wells 

completed in sand and gravel aquifers (Ohio Environmental 

Protection Agency, 2012b, table M-4B). (The glacial deposits 

of Geauga County fall within this category.) Exceedances 

were associated with reducing geochemical conditions in the 

aquifers and local areas of naturally occurring arsenic (Ohio 

Environmental Protection Agency, 2012b, p. M-22). 

Bacteria.—Bacteria data were not available for public-supply wells in Ohio’s Ambient Groundwater Quality 

Monitoring Program, so detection frequencies for bacteria in 

Geauga County were compared to data for sand and gravel 

aquifers in the neighboring state of Michigan from a study of 

38 small public-supply wells (serving less than 3,300 people) 

(Francy and others, 2004). The detection frequency4 of total 

coliform bacteria in Geauga County in 2009 was similar to the 

detection frequency found in Michigan and the United States 

as a whole (fig. 14B). In contrast, E. coli detections in Geauga 

County (0 percent) were fewer than found in Michigan and 

across the rest of the Nation (fig. 14C). 

4

 Detection frequency is discussed here rather than the exceedance 

frequency of the Ohio Department of Health human-health benchmark, 

because detection frequency was what was discussed in the National study by 

DeSimone and others (2009). 

Nitrate.—Nitrate concentrations did not exceed the MCL 

of 10 mg/L in any of the 16 domestic wells sampled in Geauga 

County in 2009 (fig 14D). (The maximum measured concentration was 1.73 mg/L.) Other data corroborate that nitrate 

concentrations in county groundwater tend to be low: (1) 

historical data for Geauga County domestic wells (93 samples 

collected by the USGS during 1978–2009) indicate that no 

domestic well samples had exceeded the nitrate MCL and (2) 

the maximum nitrate concentration measured in the seven 

public-supply well fields considered for this report was 3.85 

mg/L. Nationwide, the exceedance frequency of the nitrate 

MCL was much greater (fig. 14D) than that in Geauga County 

or the rest of Ohio. Nitrate concentrations were highest in 

agricultural areas of the Nation and in older wells (DeSimone 

and others, 2009). 

Pesticides.—Pesticides were detected in only 1 of the 16 

domestic wells sampled in Geauga County—a much lower 

detection frequency (6 percent) than was found nationwide 

(Gilliom and others, 2006) (fig. 14E). These data are not 

directly comparable, however, because the threshold concentration for pesticide detection in the current study was about 

twice that of the nationwide study,5 and fewer detections can 

be expected when a higher threshold concentration is used. 

It is also likely, however, that hydrogeology and agricultural 

management practices contribute to the relatively low detection frequency of pesticides in Geauga County. Gilliom and 

others (2006) found that, in parts of the Nation where atrazine is heavily used on corn crops, atrazine was detected less 

frequently in groundwater beneath areas covered by relatively 

impermeable soils and glacial till (such as occurs in much 

of Geauga County) than in areas with permeable soils and 

geologic formations (such as parts of Iowa, Minnesota, Pennsylvania, and Wisconsin). Gilliom and others also credited 

subsurface tile-drain systems (commonly used in Ohio to drain 

waterlogged soils) with reducing pesticide levels in groundwater by diverting shallow groundwater to streams. 

VOCs.—The detection frequencies of VOCs in Geauga 

County were not compared to nationwide detection frequencies reported by Zogorski and others (2006) because reporting levels used in the different studies were too dissimilar. 

Nonetheless, a general comparison indicates that chloroform, 

a chlorination byproduct that was detected in untreated water 

from one of four public-supply wells in Geauga County, is 

the most commonly detected VOC in Ohio’s ambient well 

network (Slattery and others, 2006) and in domestic and 

public-supply wells nationwide (Zogorski and others, 2006). 

The frequency of chloroform detection is attributed, in part, to 

the infiltration of chlorinated waters to aquifers (Zogorski and 

others, 2006). Both statewide and nationally, VOC detections 

in wells used to supply drinking water typically occurred at 

5

 The current Geauga County study uses the laboratory reporting level as 

its threshold for pesticide detection. The nationwide study by Gilliom and 

others (2006) used the long-term method detection level as its threshold. Both 

types of thresholds are defined by Oblinger Childress and others (1999). The 

laboratory reporting level is equal to the long-term method detection level 

multiplied by 2.
34 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

C D

0

2

4

6

8

10

12

14

16

18

Exceedance frequency of arsenic

MCL, 

in percent

Ohio

(242)

Geauga Co.

(16) (1,774)

U.S.

Geauga County domestic wells, 2009

Ohio public-supply wells 

(ambient network), 2001 through 2010

U.S. domestic wells, 1991 through 2004

 Number of wells sampled 

EXPLANATION

(242)

A

EXPLANATION

Geauga Co. Michigan U.S.

B

Detection frequency of E. coli bacteria, 

in percent

Michigan

(38)

Geauga Co.

(16) (397)

U.S.

Geauga County domestic wells, 2009

Michigan public-supply wells, 

1991 through 2001

U.S. domestic wells, 1991 through 2004

 Number of wells sampled 

EXPLANATION

(397)

No detections

fig. 14 A-D

0

5

10

15

20

25

30

35

40

Geauga County domestic wells, 2009

Michigan public-supply wells, 

1991 through 2001

U.S. domestic wells, 1991 through 2004

 Number of wells sampled 

(16) (38) (378)

Detection frequency of total coliform, 

in percent

(378)

Geauga County domestic wells, 2009

Ohio public-supply wells 

(ambient network), 2001 through 2010

U.S. domestic wells, 1991 through 2004

 Number of wells sampled 

EXPLANATION

Ohio

(220)

Geauga Co.

(16) (2,132)

U.S.

Exceedance frequency of nitrate MCL, 

in percent

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

No exceedances

(220)

0

5

10

15

20

25

30

35

40

Figure 14. Comparison of detection frequencies or exceedance frequencies of health-based and aesthetically based benchmarks in 

groundwater at the county, state, and national level. (Data from Desimone and others [2009], Francy and others [2004], Gilliom and others 

[2006], and Ohio Environmental Protection Agency [2012b]; MCL, Maximum Contaminant Level; SMCL, Secondary Maximum Contaminant 

Level.)
Groundwater Quality 35

G

0

10

20

30

40

50

60

Detection frequency of pesticides, 

in percent

Geauga Co. Ohio

(16) (5,047)

U.S.

Geauga County domestic wells, 2009

U.S.— shallow observation and domestic 

wells (<20 ft below the water table)

U.S.— deeper domestic and publicsupply wells tapping major aquifers

 Number of wells sampled 

EXPLANATION

(16)

E

EXPLANATION

F

U.S. Data, 1992 through 2001:

fig. 14 E-F

State data not available

Exceedance frequency of manganese SMCL,

in percent

Ohio

(235)

Geauga Co.

(16) (2,160)

U.S.

Geauga County domestic wells, 2009

Ohio public-supply wells 

(ambient network), 2001 through 2010

U.S. domestic wells, 1991 through 2004

 Number of wells sampled 

EXPLANATION

(235)

0

10

20

30

40

50

60

70

Exceedance frequency of iron SMCL, 

in percent

(16) (242) (2,160)

Geauga Co. Ohio U.S.

Geauga County domestic wells, 2009

Ohio public-supply wells 

(ambient network), 2001 through 2010

U.S. domestic wells, 1991 through 2004

Number of wells sampled 

0

10

20

30

40

50

60

70

(242)

Figure 14. Comparison of detection frequencies or exceedance frequencies of health-based and aesthetically based benchmarks in 

groundwater at the county, state, and national level. (Data from Desimone and others [2009], Francy and others [2004], Gilliom and others 

[2006], and Ohio Environmental Protection Agency [2012b]; MCL, Maximum Contaminant Level; SMCL, Secondary Maximum Contaminant 

Level.)—Continued
36 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

low concentrations that did not exceed health-based benchmarks. The only VOCs at concentrations above human-health 

benchmarks in Geauga County that were documented as part 

of this study were those found at areas of localized chemical 

releases investigated by Ohio EPA and described in the earlier 

section Water-Quality Issues Identified in Previous Investigations (fig. 11). 

Iron and manganese.—The SMCL exceedance frequencies for iron and manganese were much greater in Geauga 

County than in Ohio as a whole (Ohio Environmental Protection Agency, 2012b, table M-4B) or elsewhere in the United 

States (fig. 14 F and G). This is likely due to the naturally 

occurring reducing geochemical conditions in the county aquifers that will be discussed in a later section of the report titled 

Factors Affecting Contaminant Occurrence and Constituent 

Concentrations in Groundwater.

Occurrence of Methane in Groundwater

The occurrence of dissolved natural gas in Geauga 

County aquifers has neither been previously evaluated by the 

USGS nor examined by any of the previous water-quality 

studies summarized by Jagucki and Darner (2001). The main 

component of natural gas typically is methane, which is flammable and can cause an explosion hazard when the gas is 

released to air as water is pumped from depth to the low-pressure environment at land surface. The possibility that methane 

is present in groundwater produced by some water wells in 

the county became a concern following the investigation by 

ODNR–MRM (2008b) of a methane release related to oil and 

gas drilling in Bainbridge Township that caused an explosion 

in one house (fig. 11, site 9). During the course of their investigation, ODNR–MRM interviewed local residents and water 

well drillers, examined records for the nearby Bainbridge 

Police Department well, and collected dissolved gas samples 

from several wells in the neighborhood affected by the explosion. ODNR–MRM personnel concluded that “the occurrence 

of natural gas in groundwater for wells developed in the 

Berea-Bedford6 sequence is common in Geauga County.” 

Methane gas is colorless, tasteless, and odorless. Signs 

that methane may be present in well water include popping 

or spurting of water at the tap or milky-looking water. No 

6

 The Bedford Shale underlies the Berea Sandstone. Water well drillers 

frequently drill through the Berea Sandstone into the underlying Bedford 

Shale “to add storage capacity to domestic water wells” (Ohio Department of 

Natural Resources, 2008b, p. 24). 

adverse health effects have been linked to the drinking of or 

bathing in well water that contains methane, although extensive research on this topic has not been done (Minnesota 

Department of Health, 2011). The primary hazard posed by 

methane is that it is highly flammable. Running tapwater in a 

home can allow methane dissolved in groundwater to come 

out of solution as gas bubbles and accumulate in the air within 

the home. Methane can explode if it reaches a concentration 

of 5 percent by volume and an ignition source (such as a spark 

from an electrical outlet, well pump, pilot light, or match) 

is present. Accumulation of gas is most likely to occur in a 

basement, utility room, or bathroom where large quantities of 

water are used (Eltschlager and others, 2001). 

To evaluate the frequency of water wells that produce 

natural gas in the county in 2009, the USGS (1) screened 

16 wells across the county for combustible gas fraction at 

the wellhead and in the headspace of water samples and (2) 

analyzed samples for dissolved gases in which combustible 

gas was detected or in which exsolving gases were observed 

during sampling. Combustible gas was not detected immediately below the well cap at any of the 16 wellheads screened 

by USGS personnel in 2009. Yet when water was pumped 

from each well and the air above the water (headspace) in a 

closed container was analyzed, the headspace of three samples 

(19 percent) was found to contain detectable combustible gas 

(0.10 to 0.40 percent by volume) (table 6). All three detections were in wells tapping the Cuyahoga Group or the Berea 

Sandstone, and these detections were all less than the lower 

explosive limit of 5 percent by volume. Laboratory analyses 

of methane concentrations for these three wells ranged from 

0.0065 to 1.88 mg/L (table 6). The owner of well GE-126 

reported that the well had produced gas since it was drilled in 

the 1970s and that the quantity of gas in the well water had 

declined over time. The other two well owners did not indicate 

that they were aware of methane in their wells. The maximum 

methane concentration of 1.88 mg/L was slightly greater than 

the maximum methane concentration measured in residential 

wells following the Bainbridge Township gas release in 2007 

(measurements did not begin until after the house explosion) but was substantially less than methane concentrations 

that have been measured in residential wells in other study 

areas, including large regions of New York and West Virginia 

(table 7).
Groundwater Quality 37

Table 6. Dissolved gas concentrations in selected groundwater samples from domestic wells, Geauga County, Ohio, June 2009.

[mg/L, milligrams per liter; CH4, methane; CO2, carbon dioxide; N2, nitrogen gas; O2 , oxygen; Ar, argon. Replicate analyses are shown for each well]

 Well 

name

Date 

collected

Time 

collected Township Aquifer

Combustible 

gas in 

headspace, 

percent by 

volume

Dissolved gas concentration (mg/L)

CH4 CO2 N2 O2 Ar

GE-77 6/16/2009 1800

Chester Cuyahoga 

Group 0.15a

0.0071 33.8 24.56 0.3 0.8365

GE-77 6/16/2009 1801 0.0065 33.8 24.89 0.3 0.8429

GE-126 6/17/2009 1100

Parkman Berea 

Sandstone 0.40

0.9351 19.0 21.13 0.3 0.7755

GE-126 6/17/2009 1101 0.9918 19.1 21.29 0.3 0.7749

GE-147 6/16/2009 1400

Middlefield Cuyahoga 

Group 0.10

1.85 15.4 25.38 0.3 0.8685

GE-147 6/16/2009 1401 1.88 15.4 25.57 0.3 0.8697

a

Combustible gas was detected, but percent combustible gas by volume at this well should be considered an estimate because the instrument was not 

holding calibration well at the time of this reading.

Table 7. Studies of dissolved methane in residential water wells (modified from Bair and others, 2010, p. 3–133).

[mg/L, milligrams per liter]

Likely origin of methane (reference) Location

Number 

of wells 

sampled

Maximum 

methane 

concentration

(mg/L)

Overpressurized gas well (Bair and others, 2010) Bainbridge Township, 

Geauga County, Ohio

73 1.04a

Leakage from oil and gas production well plus 

a shallow microbial source

(Van Stempvoort and others, 2005)

Lloydminster, 

Alberta, Canada

14 26

Oil and gas production along fault zone 

(Agency for Toxic Substances and Disease 

Registry, 2003)

North Royalton, 

Cuyahoga County, Ohio

9 11

Underground natural gas storage field

(Breen and others, 2007)

Tioga Junction, Tioga 

County, Pennsylvania

39 44.8

Thermogenic methane in underlying saline groundwater and brines and some microbial methane 

from reducing (methanogenic) groundwater 

environments (Heisig and Scott, 2013)

South-central 

New York State

66 55

Coal beds, coal mining (Mathes and White, 2006) 43 counties, West Virginia 170 68.5

a

 Measurement of dissolved methane concentrations in water wells began 2 months after a house explosion indicated there was a problem 

and after additional cementing of the gas well was done to cut off the methane source.
38 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

To prevent the accumulation of gas in a well, the U.S. 

Department of the Interior, Office of Surface Mining advises 

that a vented cap be used. If methane is suspected in a well, 

a water well professional can provide advice on methods to 

vent the pressure tank associated with the well. Wells like 

those sampled in Geauga County, with dissolved methane 

concentrations less than 10 mg/L, present no immediate 

danger but do require periodic monitoring to see whether 

methane concentrations are changing over time (Eltschlager 

and others, 2001). If methane is suspected in a well, the 

local fire department can test the levels of methane inside 

the home when water is running. The level of risk can vary 

with the amount of ventilation, amount of water running, 

and air pressure on the day the test is done. As an additional 

precaution, a methane detector can be purchased that mounts 

on a wall and triggers an alarm if dangerous levels of gas have 

accumulated. Finally, the sealing of all unused wells located 

in home basements (or unused wells located outside but still 

connected by plumbing to the house) may protect a home 

from migration of methane into the house (Eltschlager and 

others, 2001). Well sealing generally involves removing the 

well casing and screen (if present) and filling the open hole 

with grout. ODNR recommends that the work be done by 

an experienced registered drilling contractor. A well sealing 

report must be submitted to ODNR, Division of Water, and to 

the Geauga County Health District.

Changes in Water Quality Over Time

Groundwater-quality data collected by the USGS in 1978, 

1980, 1986, 1999, and 2009 from the four primary aquifers 

in Geauga County (appendix table 4–1) were compared to 

evaluate changes in water quality over time. Ohio EPA’s 

public-supply data were not considered in this analysis. 

Although the same USGS laboratory was used over time and 

collection methods employed by USGS field personnel were 

largely consistent, some factors have changed over time, 

introducing variability that affects statistical analysis and 

interpretation: the list of constituents analyzed has not been 

consistent through the years, the filtering (or not filtering) 

of samples prior to analysis has not been consistent, and 

instrumentation, analytical methods, and reporting levels 

have changed over the years for some constituents. After 

consideration of these factors, the properties and constituents 

listed in tables 8 and 9 were considered comparable for 

comparison of temporal data and are the ones used in 

statistical and graphical analyses summarized below. 

Two different statistical tests were employed to compare 

constituent concentrations because a change in well-selection 

strategy in recent years resulted in two types of water-quality 

datasets: (1) a subset of USGS data consisting of samples 

from wells that were able to be resampled, 1986 to 1999 and 

1999 to 2009, and (2) the entire dataset of samples from a 

generally variable set of wells, 1978–2009 (appendix table 

4–1). Graphical techniques were used to compare detection 

frequencies and (or) concentrations of constituents with more 

than 50 percent nondetects because confounding factors 

may bias computations of statistical significance. A brief 

description of the two statistical tests used and the advantages 

and disadvantages of each test are discussed in the Methods 

section of the report.

Changes in Water Quality, 1986 to 2009 and 1999 

to 2009, in Resampled Wells

The 16 groundwater samples collected by the USGS in 

2009 were drawn from wells that had been previously sampled 

in 1999. Eleven of the16 wells had also been sampled in 

1986 (table 3, appendix table 4–1). Data from resampled or 

“paired” wells were compared, two years at a time, using the 

nonparametric Wilcoxon signed-rank test. Data from multiple 

aquifers were grouped together for this statistical test.

Results of the paired-well tests are listed in table 8 for 

frequently detected constituents (constituents detected in 

more than 50 percent of samples). Because the Wilcoxon 

signed-rank test only determines whether concentration 

values measured in two years are statistically different 

(p-value < 0.05), data for constituents deemed different 

were then evaluated graphically (fig. 15) to determine 

whether concentrations had increased or decreased with 

time. (Constituent concentrations that were the same in both 

years would plot on the red line [1:1 slope] in figure 15. The 

further a data point plots away from the red line, the greater 

the change in concentration between years.) Few constituents 

had significant changes in concentration between 1986 and 

1999 (table 8A); only chloride concentrations and the ratios 

of chloride to bromide significantly increased. Between 1999 

and 2009, however, concentrations of several constituents 

(dissolved oxygen, specific conductance, magnesium, 

alkalinity, silica, pH, bromide, organic carbon, and ammonia) 

changed significantly (table 8B). Evaluation of measurement 

variability using quality-control data (appendix 2) suggests 

that apparent changes over time in specific conductance and 

silica concentrations may actually be caused by laboratory bias 

rather than by actual changes in constituent concentrations in 

groundwater.

What do the observed changes in concentration indicate 

with regard to drinking-water quality? Health-based or 

aesthetically based benchmarks have been established for 

three of the constituents that had a statistically significant 

change in concentration between either 1986 and 1999 or 1999 

and 2009: chloride, ammonia, and pH (denoted by bolded 

text in table 8; benchmarks for each constituent are listed in 

appendix table 4–1). Chloride concentrations increased from 

1986 to 1999 (table 8A), moving toward the aesthetically 

based benchmark of 250 mg/L of chloride in drinking water, 

although the maximum concentration in the resampled wells 

was 28.8 mg/L (fig. 15A)—still quite removed from the 

concentration at which chloride will impart a salty taste to 

water. Furthermore, chloride concentrations did not continue 
Groundwater Quality 39

Table 8. Statistical test results for differences in constituent concentrations between years in samples from wells that were able to 

be resampled by the U.S. Geological Survey in Geauga County, Ohio, from 1986 to1999 or 1999 to 2009.

[n, number of samples (n is equal to the number shown in the column heading unless otherwise indicated). Properties and constituents included in table are 

those that have been consistently analyzed for over time and that have had detectable concentrations at least 50 percent of the time. Bolded constituents are 

those for which a health-based or aesthetically based benchmark has been established (U.S. Environmental Protection Agency, 2006, 2009). The Wilcoxon 

signed-rank test was used to evaluate differences in concentration distributions between years. Highlighted values (orange or blue) are statistically different at 

the 95-percent confidence level (p-value <0.05). Direction of change (increase or decrease in concentration over time) was determined by visually evaluating 

scatterplots of the data shown in fig. 15]

A 1986 to 1999 B 1999 to 2009

Properties or constituents p-value 

(n=11)

Direction of change 

in concentration Properties or constituents p-value (n=16)

Direction of change 

in concentration

Dissolved oxygen1 0.1878

No significant 

change

Dissolved oxygen 0.0005

Increased

Specific conductance1 0.7211 Specific conductance3 0.0063

Magnesium 0.6247 Magnesium 0.0385

Alkalinity 0.1190 Alkalinity 0.0213

Silica 0.1076 Silica3 0.0060

pH 0.0726 pH 0.0020

Decreased

Bromide 0.9287 Bromide 0.0196

Ammonia 0.6875 Dissolved organic carbon 0.0014

Hardness 0.5312 Ammonia 0.0005

Calcium 0.5333 Hardness 0.1044

No significant 

change

Sodium 0.7002 Calcium 0.1439

Potassium 0.4648 Sodium 0.1591

Sulfate 0.7969 Potassium 0.1268

Chloride2 0.0010

Increased

Sulfate 0.0739

Chloride to bromide ratio 0.0020 Chloride 0.5694

Dissolved solids 0.9645

No significant 

change

Chloride to bromide ratio 0.0739

Iron 0.1230 Dissolved solids 0.0979

Manganese 0.5771 Iron 0.7560

1

 For dissolved oxygen, n=8; for specific conductance, n=10. Manganese 0.4372

2

 The statistical test used for this analysis is more sensitive to changes 

in individual wells than the one used by Jagucki and Darner (2001), who 

found no significant change in chloride concentration from 1986 to 1999.

3

 Quality-control data suggest that apparent changes in specific conductance from 1999 to 2009 may be within the range of expected sensor and 

sampling accuracy and may not represent an actual change in groundwater 

chemistry. Likewise, apparent changes in concentrations of silica from 

1999 to 2009 may be the result of laboratory bias (change in recovery) and 

may not be caused by an actual change in groundwater chemistry. 

See appendix 2.

What is a p-value?

The p-value describes the statistical significance of the test result for a constituent, which in this 

report means the percent chance that the statistical test result occurred by chance if there really are no 

changes in constituent concentration with time. The smaller the p-value, the stronger the scientific evidence that constituent concentrations measured in different years are really different, or that constituent 

concentrations are really correlated to time (sampling year). For example, a p-value of 0.01 indicates 

that there is a 1 percent chance that the statistical test result occurred by chance alone (Helsel, 2005). 

For all statistical tests in this report, the result was deemed to be statistically significant if the p-value 

was less than 0.05. 
40 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

300

400

500

600

700

800

900

300 500 700 900

1999 specific conductance, 

in microsiemens per centimeter

 

Apparent change may 

be within the range of 

sensor and sampling 

accuracy and may not 

represent an actual 

chemical change 

E

0

10

20

30

40

0 10 20 30 40

2009 magnesium concentration, 

in milligrams per liter

F

2009 specific conductance, 

in microsiemens per centimeter

1999 magnesium concentration, 

in milligrams per liter

Higher in 2009

Higher in 1999

No change

Higher in 2009

Higher in 1999

No change

Higher in 1999

Higher in 2009

0

1

2

3

4

5

6

7

0 1 2 3 4 5 6 7

2009 dissolved oxygen concentration, 

in milligrams per liter

1999 dissolved oxygen concentration, 

in milligrams per liter

No change

0

200

400

600

800

0 200 400 600 800

1999 ratio of chloride to bromide

1986 ratio of chloride to bromide

Higher in 1999

Higher in 1986

B

No change

Higher in 1999

Higher in 1986

No change

0

5

10

15

20

25

30

0 5 10 15 20 25 30

1986 chloride concentrations,

in milligrams per liter 

A

1999 chloride concentrations,

in milligrams per liter 

C D

No change

Higher in 1999

Higher in 2009

4

5

6

7

8

4 5 6 7 8

1999 pH, in standard units

2009 pH, in standard units

fig.15 A-F

Figure 15. Properties and constituents with a statistically significant change in concentration from 1986 to 1999 or 1999 to 2009 in 

resampled wells, Geauga County, Ohio.
Groundwater Quality 41

fig. 15 G-K

K

2009 organic carbon concentration, 

in milligrams per liter 

0

0.2

0.4

0.6

0.8

1.0

1.2

0 0.2 0.4 0.6 0.8 1 1.2

1999 organic carbon concentration, 

in milligrams per liter 

No change

Higher in 2009

Higher in 1999

J

100

150

200

250

300

350

400

100 150 200 250 300 350 400

1999 alkalinity, in milligrams 

per liter as calcium carbonate

2009 alkalinity, in milligrams 

per liter as calcium carbonate

Higher in 1999

Higher in 2009

No change

I

1999 ammonia concentration, 

in milligrams per liter

2009 ammonia concentration, 

in milligrams per liter

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

No change

Higher in 2009

Higher in 1999

0

0.05

0.10

0.15

0.20

0.25

0 0.05 0.1 0.15 0.2 0.25

Higher in 1999

Higher in 2009

H

No change

1999 bromide concentration, 

in milligrams per liter

2009 bromide concentration, 

in milligrams per liter

5

10

15

20

5 10 15 20

1999 silica concentration, 

in milligrams per liter

Apparent change may 

be the result of 

laboratory bias and 

may not represent an 

actual chemical change

G

2009 silica concentration, 

in milligrams per liter

No change

Higher in 2009

Higher in 1999

Figure 15. Properties and constituents with a statistically significant change in concentration from 1986 to 1999 or 1999 to 2009 in 

resampled wells, Geauga County, Ohio.—Continued
42 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

to increase from 1999 to 2009. Ammonia concentrations 

decreased from 1999 to 2009 (table 8B, fig. 15I) and are thus 

moving farther away from the health-based benchmark of 30 

mg/L as N (the ammonia concentration at or below which 

there are not expected to be any adverse health effects over 

a lifetime of exposure). Lastly, the observed decrease in pH 

from 1999 to 2009 (table 8B) is a move in direction toward 

the lower aesthetically based limit (SMCL) of 6.5 pH units, 

with one of the resampled wells already having a pH below 

this limit (fig. 15C). For the majority of wells, however, the 

decrease in pH is only of concern if changes in the same 

direction continue in subsequent years. 

The observation of statistically significant changes in 

concentrations of some constituents between two sampling 

years does not necessarily indicate that these changes are 

human induced. Annual variations in precipitation cause 

variations in the amount of recharge to the groundwater 

system from year to year. For example, the increase in the 

amount of dissolved oxygen in samples from 1999 to 2009 

is consistent with several years of above-normal annual 

precipitation preceding the 2009 sampling round (fig. 3), 

because atmospheric oxygen dissolved in precipitation is the 

source of dissolved oxygen to groundwater. As a result of 

fluctuations in annual precipitation amounts, concentrations 

of many groundwater constituents can fluctuate in response 

to influx of constituents from land surface, dilution of 

constituents in groundwater by infiltrating rainwater, or 

changes in groundwater flow rates that affect contact time 

between groundwater and aquifer minerals, thereby affecting 

mineral dissolution rates. In contrast, a consistent trend in 

constituent concentrations over several years is of greater 

concern because it implies that some type of long-term 

environmental change (either natural or human induced) has 

affected water quality.

Changes During 1978–2009 in Concentrations of 

Frequently Detected Constituents 

Water-quality data in Geauga County have been collected 

over a long period of time (1978–2009) relative to most other 

counties in Ohio. To utilize data from the entire period of 

record (rather than merely examine temporal changes between 

the most recent sampling rounds), a different statistical test 

had to be employed because a substantial amount of the 

water-quality data (appendix table 4–1) are not from resampled wells. It was not possible to sample the same group of 

wells during each sampling round because of (a) wells being 

destroyed or replaced over time, (b) changes in access permission from homeowners, or (c) changes in monetary resources, 

limiting the number of samples that could be analyzed during 

some years. Changes in constituent concentrations analyzed 

during three or more years between 1978 and 2009 were statistically evaluated by using the nonparametric Spearman’s rho 

correlation test. The correlation coefficient produced by this 

test measures the strength of the association between sampling 

year (time) and constituent concentration (or how likely it is 

that concentration consistently increases or decreases as time 

increases). A benefit of the test is that temporal trends within 

each aquifer can be evaluated. 

Statistical results (table 9) indicate that, at a 95-percent 

confidence level (p-value less than 0.05), the majority of 

constituents showed no consistent temporal trend in concentration. Dissolved oxygen, calcium, and sulfate concentrations and chloride:bromide ratios increased over time in one 

or more aquifers, while pH and concentrations of bromide 

and dissolved organic carbon decreased over time. Many of 

these results are similar to those observed between 1986 and 

1999 or between 1999 and 2009 in resampled wells (table 8). 

What do correlation coefficients mean?

A correlation coefficient (rho) measures the strength of the monotonic relation between two constituents 

or parameters. The closer the value of rho to 1 or −1, the stronger the correlation. A positive correlation 

coefficient means that as the concentration of one constituent increases, so does the concentration of the 

other. A negative correlation coefficient means that as the concentration of one constituent increases, the 

concentration of the other constituent decreases. All correlations presented were statistically significant 

at a 95-percent confidence interval (p-value <0.05). For the purposes of this report, the strength of the 

correlation between two properties or constituents is defined as follows, based on rho: strong, rho is 

greater than 0.75; good, rho is 0.50 to 0.75; fair, rho is 0.20 to 0.50; poor, rho is less than 0.20).
Groundwater Quality 43

Table 9. Correlation of chemical properties or constituents of wells sampled by U.S. Geological Survey, 1978–2009, to year sampled. [ft, feet; n, number of samples in dataset; —, no statistically significant correlation (p <0.05) was found between year and constituent concentration. Bolded properties and constituents are ones for which a health-based or aesthetically based drinking-water benchmark has been established (U.S. Environmental Protection Agency, 2006, 2009). Correlations were evaluated by using the Spearman’s rho correlation test. Constituent concentrations are listed by sampling year in appendix table 4–1]

Characteristic, 

property, or 

constituent

Years property or constituent 

was analyzed for

Correlation coefficient and number of samples in dataset

Direction of 

change 

with time All wells

Aquifer

1978

1980

1986

1999

2009Glacial deposits Pottsville Formation Cuyahoga Group Berea Sandstone

Dissolved oxygen X X X 0.65 (n=76) 0.68 (n=18) 0.73 (n=24) 0.73 (n=20) —

Increased 

Calcium X X X X X — — — 0.40 (n=27) —Sulfate X X X X X — — — 0.55 (n=27) —Ratio chloride:bromide X X X 0.27 (n=83) 0.51 (n=18) — 0.44 (n=20) —pH X X X X X — — — –0.59 (n=27) —

Decreased Bromide X X X –0.34 (n=83) — — –0.53 (n=20) —

Dissolved organic carbon X X X –0.70 (n=57) — –0.74 (n=17) –0.79 (n=16) –0.89 (n=11)Specific conductance X X X X X — — — — —

Not correlated 

to time

Dissolved solids X X X X X — — — — —Magnesium X X X X X — — — — —Potassium X X X X X — — — — —Sodium X X X X X — — — — —Alkalinity1 X X X X X — — — — —Chloride X X X X X — — — — —Fluoride X X X X — — — — —Silica X X X X X — — — — —Ammonia X X X X X — — — — —Iron X X X X X — — — — —Manganese X X X X X — — — — —Arsenic X2 X2 X — — — — —

1For statistical testing, acid-neutralizing capacity data (1978–1986) were combined with alkalinity data (1999–2009). These two parameters are equivalent in samples without titratable particulate matter. 2Only selected samples were analyzed for arsenic during this year. See appendix table 4–1.
44 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Constituent concentrations in samples from the Berea Sandstone were largely unchanged over time (table 9). This is not 

surprising because the Berea Sandstone is the aquifer containing the oldest water (fig. 2) and thus is the aquifer least likely 

to be affected by human-induced (or natural) changes near 

land surface. In contrast, samples from the Cuyahoga Group 

had the greatest number of constituents with concentrations 

exhibiting temporal trends. Test results for temporal trends in 

the Cuyahoga Group do not appear to be biased by differences 

in construction characteristics of the wells sampled in different 

years because none of the following construction characteristics of Cuyahoga wells were correlated to sampling year at 

a statistically significant level (p <0.05): depth or elevation 

of well bottom, depth or elevation of top of open interval, or 

depth to water. 

Of the constituents found to be statistically correlated 

to time, 1978–2009, only sulfate and pH have an drinkingwater benchmark (shown as bolded parameter names in 

table 9) against which to gage direction of change. As 

previously stated, the decrease in the pH is a move in 

direction toward the lower SMCL of 6.5 pH units. Temporal 

changes in concentrations of sulfate in the Cuyahoga Group 

were illustrated graphically by using boxplots (fig. 16). 

Boxplots allow visual comparison among years of median 

concentration, interquartile range (the distribution of the data 

that lie between the 75th percentile and the 25th percentile), 

and the total range of measured values. The boxplots show that 

median sulfate concentrations increased during 1986–2009. 

Despite this trend, the maximum sulfate concentration in 2009 

(140 mg/L) was still considerably below the aesthetically 

based benchmark of 250 mg/L. 

Temporal changes in concentrations of bromide and 

dissolved organic carbon and in chloride:bromide ratios 

(constituents or ratios that do not have health-based or 

aesthetically based benchmarks but that were prevalent 

enough to be detected in a dataset of all wells [table 9]) 

are also graphically shown by means of boxplots (fig. 17). 

Possible reasons for these trends are discussed in the Factors 

Affecting Contaminant Occurrence section of the report. 

x

(4) (3) (8) (7) (5)

Year

(30) Number of samples

EXPLANATION

x

Upper adjacent value

75th percentile

Median

25th percentile

Lower adjacent value

Upper outside value

200

150

100

50

0

1978 1980 1986 1999 2009

Sulfate concentration, in milligrams per liter

Figure 16. Changes in sulfate concentrations, 1978–2009, in samples from the Cuyahoga Group, Geauga County, Ohio.
Groundwater Quality 45

(0) (0) (37) (30) (16)

1978 1980 1986 1999 2009

Chloride:bromide ratio 

10,000

1,000

100

10

Year

(0) (0) (37) (30) (16)

Bromide concentration, in milligrams per liter

1.00

0.50

0.10

0.05

0.01

1978 1980 1986 1999 2009

Common reporting level=0.02

x

x

1978 1980 1986 1999 2009

Year

(11) (0) (0) (30) (16)

Dissolved organic carbon, 

in milligrams per liter

x

6

5

4

3

2

1

0

Year

x

x

x

Not analyzed for

Not analyzed for

Not analyzed for

Not analyzed for

Not analyzed for

Not analyzed for

(30) Number of samples

EXPLANATION

Upper adjacent value

75th percentile

Median

25th percentile

Lower adjacent value

Upper outside value

FIG 17

A B

C

Figure 17. Changes of selected constituent ratios and concentrations in all wells sampled by the U.S. Geological Survey in Geauga 

County, Ohio, 1978–2009: A, Chloride:bromide ratios. B, Concentrations of bromide. C, Concentrations of dissolved organic carbon.

Changes Over Time Of Constituents With 

Infrequent Detections

Total coliform bacteria, nitrate, orthophosphate, and 

sulfide were analyzed for during three or more years from 

1978 through 2009 from an inconsistent set of wells but had 

more than 50 percent nondetects when censored to a common 

reporting level. For these constituents, changes over time were 

evaluated by comparing the detection frequency each year and 

(or) by comparing concentrations in resampled wells. 

The detection frequency of total coliform bacteria was 

higher in 1999 (53 percent) than in 2009 (33 percent) for all 

wells sampled in the county (appendix table 4–1). After the 

relatively high detection frequencies for bacteria measured 

in 1999, owners of wells in which bacteria were detected 

were advised to treat their wells with shock-chlorination 

to kill the bacteria; this might have contributed to the 

difference in detections of total coliforms from 1999 to 

2009. Concentrations of total coliforms at individual wells 

were compared for the 16 wells sampled in 1999 that were 

resampled in 2009. Total coliform bacteria were detected at a 

concentration greater than or equal to 1 colony-forming unit 

per 100 mL of water in 11 of the 16 wells in either 1999 or 

2009, but in both years in only 2 wells (fig. 18). Of the two 

wells with detections both years, total coliforms increased 

from 1999 to 2009 in only one well (GE-141). 
46 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

GE-108GE-141GE-165

GE-85A

GE-151

GE-202

GE-332GE-147

GE-185A

GE-234

GE-120

Wells with samples containing total coliforms 

Total coliform bacteria,

in colony-forming units per 100 milliliters

0

20

40

60

80

100

120

1999

2009

Years sampled

EXPLANATION

Glacial deposits Pottsville Formation Cuyahoga Group Berea

 Ss.

Figure 18. Comparison of total coliform 

concentrations in 1999 and 2009 in samples 

from wells with at least one detection, 

Geauga County, Ohio. (Ss., sandstone.)

Because nitrate is detected much more frequently in 

wells producing water from the Pottsville Formation than 

in wells that tap other aquifers (fig. 19A), change over time 

was evaluated by comparing the nitrate detection frequency 

only in samples from the Pottsville Formation (fig. 19B). 

(This eliminates variability in detection frequency between 

years caused by sampling a different percentage of Pottsville 

wells each year.) Nitrate in groundwater is of interest because 

a health-based standard has been established for nitrate 

in drinking water and because human influences (such 

as application of fertilizer and biosolids, or failing septic 

systems) can be a source of nitrates to groundwater, along with 

natural sources. Although population has increased during 

each decade in Geauga County (fig. 4) (and presumably, so 

have human sources of nitrates), detections of nitrate (fig. 19B) 

have not consistently become more frequent over time.

The well assemblage sampled each year may also 

influence the detection frequency of orthophosphate in a 

given year, because orthophosphate was detected more 

frequently in wells tapping the Cuyahoga Group and 

the Berea Sandstone than in wells open to the Pottsville 

Formation and glacial deposits (fig. 20). To eliminate this 

potential bias, concentrations from wells that had detectable 

orthophosphate (greater than or equal to 0.01 mg/L) in 

one or more years (1986, 1999, or 2009) were examined 

by well (fig. 21). For these eight wells, detections of 

orthophosphate were more frequent in 2009 than in preceding 

years. Increases in orthophosphate detections are of interest 

because orthophosphate can indicate pollution from laundry 

wastewater, commercial cleaning wastes, sewage, or fertilizer 

(Hem, 1989). 

Total sulfide was measured in only about one-third of the 

wells sampled by the USGS in 1986 and in all wells sampled 

in 1999 and 2009 (appendix table 4–1, fig. 22). Detection 

frequency of sulfide has increased in each subsequent year 

from 1986 through 2009 (fig. 22). To evaluate changes in 

concentration of sulfide over time, concentrations from wells 

that had detectable sulfide (greater than or equal to 0.01 

mg/L) in 1999 and (or) 2009 were examined by well (fig. 

23). Only data for 1999 and 2009 were compared because 

laboratory reporting levels were an order of magnitude higher 

in 1986 (0.1 mg/L) than in subsequent years (0.01 mg/L). 

Of the 16 wells that were sampled in both 1999 and 2009, 

10 had detectable sulfide (≥0.01 mg/L) in one or both years 

(fig. 23). Of these 10 wells, 60 percent showed an increase 

in sulfide concentration between 1999 and 2009. All wells 

tapping the Cuyahoga Group showed increases, while total 

sulfide concentrations in water from both of the Pottsville 

wells decreased. Sulfide concentrations are of interest because 

sulfide can combine with iron to form black iron sulfide 

particulates in water or pressure tanks or can form hydrogen 

sulfide that causes the undesirable rotten-egg smell.

In summary, detections of total coliform and nitrate have 

not become more frequent countywide from 1986 to 2009, 

even though the county population has increased during this 

period; however, a few individual wells have shown increases 

in concentrations of these constituents. Orthophosphate and 

sulfide detections were more frequent in 2009 than in previous 

years. 
Groundwater Quality 47

B

0

10

20

30

40

50

60

70

80

90

100

1978 1980 1986 1999 2009

Detection frequency in Pottsville wells, 

in percent

Year

(3) (10) (14) (9) (5)

0

10

20

30

40

50

60

70

80

90

(26) (41) (27) (22)

A 100

Glacial Pottsville Cuyahoga Berea

Detection frequency, in percent

Aquifer

Figure 19. Detection frequency 

of nitrate in Geauga County, Ohio, 

1978–2009, when censored to a 

common reporting level of 0.18 

milligram per liter (number in 

parentheses denotes number of 

samples in each category). 

A, By aquifer. B, In samples from 

the Pottsville Formation.

0

10

20

30

40

50

Glacial Pottsville Cuyahoga Berea

Detection frequency, in percent

Aquifer

(18) (28) (20) (17)

Figure 20. Detection frequency of orthophosphate 

in Geauga County, Ohio, by aquifer, 1986–2009, when 

censored to a common reporting level of 0.01 milligram 

per liter (number in parentheses denotes number of 

samples in each category).
48 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

0

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0.016

0.018

0.020

Wells with samples containing orthophosphate

Common reporting level 

GE-109 GE-202 GE-77 GE-147 GE-185A GE-103 GE-120 GE-126

1986

1999

2009

Orthophosphate concentration, in milligrams per liter

Years sampled Values less than the common reporting 

level (nondetects) are shown as = 

0.005 milligram per liter (mg/L). Values 

at the common reporting level (0.01 

mg/L) were actual detections.

Pottsville Formation Cuyahoga Group Berea Sandstone

Figure 21. Orthophosphate concentrations, 1986–2009, for wells in Geauga County, Ohio, producing water with a concentration 

greater than or equal to 0.01 milligram per liter in one or more years. (Samples in 1999 were analyzed by Heidelberg University, 

Tiffin, Ohio. Samples in 1986 and 2009 were analyzed by the U.S. Geological Survey National Water Quality Laboratory.)

0

5

10

15

20

25

30

35

1978 1980 1986 1999 2009

Detection frequency, in percent

Year

(0) (0) (12) (30) (16) Not analyzed for Not analyzed for

Figure 22. Detection frequency of total 

sulfide by year, Geauga County, Ohio, 

1986–2009. (Detection frequency calculated 

by using a common reporting level of 0.1 

milligram per liter. Number in parentheses 

denotes number of samples in category.)
Glacial deposits Pottsville 

Formation

Cuyahoga Group Berea Sandstone

0

0.1

0.2

0.3

0.4

0.5

GE-108 GE-141 GE-165 GE-202 GE-332 GE-77 GE-147 GE-234 GE-120 GE-126

Total sulfide concentration, in milligrams per liter

Wells with samples containing sulfide

1999

2009

Years sampled 

Common reporting level = 0.01mg/L 

Values less than the 

common reporting level 

(nondetects) are shown 

as = 0.005 milligram per 

liter (mg/L). Values at the 

common reporting level 

(0.01 mg/L) were actual 

detections.

Groundwater Quality 49

Figure 23. Sulfide concentrations in Geauga County, Ohio, 1999 and 2009, for wells producing water with 

a sulfide concentration greater than or equal to 0.01 milligram per liter in one or both years.

Factors Affecting Contaminant Occurrence and 

Constituent Concentrations in Groundwater

Eberts and others (1990) and Jagucki and Darner (2001) 

discussed some of the factors that influence water quality 

in Geauga County on the basis of groundwater analyses 

from a single year (1986 and 1999, respectively). To build 

upon this knowledge and gain new insights, the relations 

of water-quality constituent concentrations to factors such 

as well construction, well position relative to groundwater 

flow paths, and depth to groundwater were reexamined by 

using all available USGS data collected in the county from 

1978 through 2009—as many as 116 samples from 65 wells 

(appendix table 4–17

 and appendix fig. 4–1). Additionally, 

7

 Exceptions—The following constituents in appendix table 4–1 were 

not used in the correlation tests: water temperature and (because of very 

infrequent detections) phosphorus, E. coli, fecal coliform, fecal streptococcus, 

and dissolved methane.

the relations of constituent concentrations to upgradient land 

cover were evaluated by using data from the 16 domestic 

wells sampled in 2009 (appendix table 3–1). The strength 

of the associations between constituent concentrations and 

explanatory factors was evaluated by using the Spearman’s 

rho correlation coefficient and graphing techniques. Factors 

found to be related to elevated constituent concentrations 

in groundwater are described in the following sections. 

These results may aid planning officials and homeowners in 

determining where various manmade and naturally occuring 

groundwater contaminants may be expected. 
50 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Human Activities at Land Surface

Greater concentrations of a constituent in groundwater 

near the land surface than at depth may indicate a near-landsurface source. The correlation between well depth (either 

depth to top of open interval or depth of well bottom) and 

the properties and constituents listed in appendix table 4–1 

were assessed for all samples collected by USGS, 1978–2009. 

Concentrations of four constituents—chloride, total coliform 

bacteria, nitrate, and sulfate—and the chloride:bromide ratio 

decreased significantly with depth (fig. 24). These constituents, and others that are manmade or thought to be affected by 

human activities at land surface, are discussed below. 

Sources of Salinity

Septic-system leachate is a potential source for the four 

constituents that had higher concentrations in groundwater 

near land surface than at depth (fig. 24). These constituents 

also have other sources (table 10). Of these four constituents, 

chloride is the most stable in groundwater, meaning that it 

does not tend to transform, dissipate, or interact with aquifer 

materials. Thus, chloride was considered, for the purposes of 

this report, to be the most reliable indicator of human influence on groundwater quality near land surface. Most samples 

with chloride concentrations greater than 12 mg/L—the 

approximate upper limit of concentrations in water from unaffected, or “background,” wells in Ohio and the Midwest, as 

determined by Jones and Sroka (1997) and Panno and others 

(2005)—are from areas with shallow groundwater (less than 

about 50 ft below land surface) (fig. 25). The highest concentrations (greater than 130 mg/L) are in areas with depth 

to water of less than 30 ft below land surface. To distinguish 

which chloride sources might be influencing shallow groundwater in Geauga County, various lines of evidence were 

investigated (table 11). Brines (either from spills of water 

produced during oil and gas drilling or from spraying of 

drilling brines on roads to reduce dust) were eliminated as a 

significant source of chloride to shallow groundwater, because 

chloride:bromide ratios in shallow waters that have elevated 

chloride concentrations (greater than 12 mg/L) were usually 

greater than the ratio of 95 that is characteristic of local drilling brine (Eberts and others, 1990). Rather, chloride:bromide 

ratios in shallow groundwater samples with chloride concentrations exceeding background levels were generally greater 

than 400 (fig. 25), which is a range that Panno and others 

(2006) associated with Midwestern groundwater affected by 

septic effluent or road salt. Differentiating between the effects 

of septic leachate and road salt, however, is difficult. The lines 

of evidence examined in table 11 indicate that both septic 

leachate and road salt may contribute chloride to shallow 

groundwater in Geauga County. The correlation of chloride 

concentration to distance from road for 31 wells sampled in 

1999 (Jagucki and Darner, 2001)—with greater concentrations 

found in wells nearer a road—suggests that road salt is the 

dominant source. Wells GE-23 and GE-341 (fig. 25) both are 

within 50 ft of a road and have water levels that are less than 

20 ft below land surface. Additionally, well GE-69 (fig. 25) 

is within a few hundred feet of a storage area for road salt 

(Eberts and others, 1990, p. 57) and has a water level that is 

less than 30 ft below land surface. 

More densely populated areas of Geauga County likely 

have a greater number of septic systems (except for sewered 

areas) and a greater amount of road salt applied (associated 

with a denser road network) than areas of lower population 

density. Whereas chloride concentration was not significantly 

correlated to population density for the 16 domestic well 

samples from 2009, chloride concentrations did increase as 

percent developed plus agricultural land cover increased 

(rho = 0.56, p-value = 0.0235). 

Septic leachate (or possibly the spreading of biosolids) is 

a likely source of salinity to well GE-141 (table 11; fig. 25). 

The chloride:bromide ratio increased in samples from GE-141 

from 420 to 1,340 between 1986 and 2009, indicating ongoing 

inputs of salinity not originating from brine. Specific conductance and sodium concentrations also increased between 

1986 and 2009 in samples from this well (appendix table 4–1). 

Well GE-141 is more likely than many of the other wells to be 

vulnerable to contamination sources near land surface because 

of its shallow total depth (53 ft below land surface) and the 

shallow water table (only 8.14 ft below land surface in 2009) 

at this location. Samples from well GE-141 had an increase in 

total coliform concentration from 1999 (19 colonies/100 mL) 

to 2009 (49 colonies/100 mL) and a fecal coliform detection 

in 2009, which strengthens the evidence that a fecal source has 

affected groundwater near this well. GE-141 is the only one 

of the 16 domestic wells sampled in 2009 to have permitted 

biosolids spreading within 500 m upgradient from the well. 

Yet, it is unclear whether the 9.9-acre field, which is authorized for land application of biosolids from the McFarland 

Creek Wastewater Treatment Plant (WWTP), has ever actually 

been used for biosolids spreading. Jerry Morgan of the Geauga 

County Department of Water Resources reports that during 

his tenure (2006 to present) the McFarland Creek WWTP has 

not applied biosolids to this (or any) field but has instead sent 

them to a permitted landfill (oral commun., Feb. 11, 2014). On 

the basis of fecal coliform survival rates in Florida groundwater (John and others, 2004), it seems unlikely that bacteria 

originating from biosolids spreading prior to 2006 would 

survive in groundwater through 2009. John and others (2004) 

showed a 99 percent die-off of fecal coliforms over a period of 

2–6 weeks.
Groundwater Quality 51

0

50

100

150

200

250

0 50 100 150 200 250 300

Depth to top of open interval, 

in feet below land surface

Chloride concentration, in milligrams per liter

0

50

100

150

200

250

300

350

0 50 100 150

Depth of well bottom, 

in feet below land surface

Total coliform concentration, 

in colonies per 100 milliliters

Glacial deposits

EXPLANATION

Pottsville Formation

Cuyahoga Group

Berea Sandstone

0

50

100

150

200

250

0 1 2 3 4 5 6

Depth to top of open interval, in feet below land surface 

Nitrate concentration, in milligrams per liter

C

A

D

B

0

50

100

150

200

250 0 200 400 600

Depth to top of open interval, 

in feet below land surface

Sulfate concentration, in milligrams per liter

Spearman's rho = -0.29

p-value = 0.0093

Number of samples = 77 

Spearman's rho = -0.30

p-value = 0.0082

Number of samples = 77 

Spearman's rho = -0.38

p-value= 0.0095

Number of samples = 46 

(1999 and 2009 only)

Spearman's rho = -0.24

p-value= 0.0339

Number of samples = 77

GE-122

Figure 24. Relation of selected constituent concentrations to well depth for samples collected by the U.S. Geological Survey, Geauga 

County, Ohio, 1978–2009. A, Chloride. B, Total coliform bacteria. C, Nitrate. D, Sulfate. (Open interval is the uncased part of the well, 

through which groundwater enters the well.)
52 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Table 10. Possible sources near land surface of selected constituents in groundwater.

Constituent Possible sources near land surface Stability in groundwater

Chloride Septic leachate, road salt, spills of brines produced during oil and gas 

drilling or spraying of drilling brines on roads for dust control

Stable.

Total coliform 

bacteria

Septic leachate, livestock manure, application of biosolids or septage to 

agricultural fields, soils

Dies off under typical 

groundwater conditions.

Nitrate Septic leachate, fertilizer, livestock manure, application of biosolids or 

septage to agricultural fields, nitrogen-fixing plants and decomposing plants 

Transforms to ammonia 

and (or) nitrogen gas in 

a reducing geochemical 

environment.

Sulfate Septic leachate, combustion of fossil fuels, fertilizer, livestock manure, 

field application of biosolids or septage

Transforms to sulfide in a 

reducing geochemical 

environment.

140

50 100 150 200 250 300

Chloride concentration, in milligrams per liter

Background

concentration

700 750 800

0

20

40

60

80

100

120

0

Depth to water, in feet below land surface

GE-69

EXPLANATION

Aesthetically baseddrinking-water standard

Cl:Br < 150

Cl:Br 150 to 400

Cl:Br 401 to 1100

Cl:Br > 1100

Spearman’s rho=−0.34; p-value=0.0017

Number of samples=83

GE-23

GE-341

GE-141

Figure 25. Relation of chloride concentration to depth to water for samples collected by the U.S. Geological Survey in Geauga 

County, Ohio, 1986–2009. (Cl:Br, ratio of chloride to bromide.)
Groundwater Quality 53

Table 11. Lines of evidence investigated to distinguish between sources of salinity in groundwater of Geauga County, Ohio.

[>, greater than; Cl:Br, ratio of chloride to bromide; , the evidence presented supports this source; X, the evidence presented rules out this source; x, the 

absence of the presented correlation or detection does not rule this source out, but its presence would have confirmed this source; —, not applicable to this 

source.]

Applicability Evidence investigated

Salinity source

Road 

salt

Septic 

leachate1 Brine

Countywide

(1) Chloride concentration decreases with depth (indicates surface source).   

(2) Chloride concentration is > 12 mg/L (background concentration) in shallow 

groundwater.

  

(3) Cl: Br is > 400 in most groundwater samples with chloride 

concentration > background.

  X

(4) Chloride concentrations and Cl:Br are positively correlated to concentrations 

of nitrate (which can have a septic source).

—  —

(5) Total coliform bacteria concentrations (which can have a septic source) are 

not correlated to concentrations of chloride or nitrate, or to Cl:Br.

— x —

(6) Concentrations of other indicators of septic leachate (boron [present in some 

laundry detergents], potassium, sulfate, organic carbon) are not significantly 

correlated to concentrations of chloride, total coliform, or to each other.

— x —

(7) E. coli bacteria, which only have a fecal source, were not detected in any 

wells.

— x —

(8) Chloride concentration was positively correlated to distance from road for 31 

wells sampled in 1999 (Jagucki and Darner, 2001).

 — 

(9) Chloride concentration is positively correlated to percent developed plus 

agricultural land cover.

  —

Single well

(10) Concentration of total coliform bacteria increased in well GE-141 from 1999 

to 2009.

—  —

(11) Fecal coliform bacteria were detected in well GE-141 in 2009 (strengthens 

evidence that bacteria in well have a fecal source).

—  —

1

 Evidence indicating that septic leachate is influencing shallow groundwater could also be used to suggest that biosolids or septage are affecting water 

quality. However, septic leachate was determined to be a more likely source to wells sampled in the county, because only one well (GE-141) had a permitted 

biosolids-spreading field within 500 meters upgradient of the well, and biosolids had not been spread on this field since prior to 2006 (if ever).
54 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Other Factors That Can Influence Concentrations of Total 

Coliform Bacteria, Nitrate, and Sulfate 

Bacteria.—Concentrations of total coliform bacteria 

in water from wells in Geauga County were determined in a 

total of 46 samples collected by the USGS in 1999 and 2009 

(appendix table 4–1). With a couple of exceptions, the most 

elevated concentrations of total coliforms were found in 

wells with bottom depths of 70 ft or less below land surface 

(fig. 24B). No concentrations exceeding the health-based 

standard of 4 colonies per 100 mL occurred in wells with 

bottom depths greater than 140 ft below land surface. Total 

coliforms were also negatively correlated to depth to top of 

open interval (rho = −0.35, p-value = 0.018), meaning that 

greater concentrations occurred in wells with shallow cased 

intervals. Total coliform concentrations in water samples from 

the 16 wells sampled in 2009 were not correlated to any land 

use factors or population density. In fact, the only factor other 

than well construction that was significantly correlated to total 

coliform concentration was turbidity (rho = 0.66, p-value = 

0.0056) (fig. 26). This result is expected, because bacteria 

tend to cling to particulates rather that float freely in water. 

During the 2009 sampling round, four of the six samples 

with turbidity above 5 nephelometric turbidity units (NTU) 

contained detectable total coliform bacteria (fig. 26); 5 NTU is 

the threshold for visible turbidity (Strausberg, 1983). Turbidity 

values greater than about 25 NTU might indicate failure of the 

well casing or improper well construction (U.S. Geological 

Survey, 1997–present, chapter 4.2.2.A, p. 91) that allows 

surface runoff (and any associated total coliform bacteria) to 

directly enter the well. Elevated turbidity may also be caused 

by precipitating sulfide minerals, which would appear as finely 

disseminated black particulates in groundwater. (Samples from 

a geochemical environment conducive to the precipitation of 

sulfide minerals are indicated by red circles in fig. 26).

Nitrate.—Nitrate concentrations greater than 1 mg/L 

occurred primarily in domestic wells tapping the Pottsville 

Formation with casing that extends less than 75 ft below 

land surface (fig. 24C). In addition, the highest nitrate 

concentrations in water from domestic wells were found in 

areas with the greatest percentage of agricultural land use 

(fig. 27A) or developed land use (fig. 27B) (although the 

association was not statistically significant). Developed and 

agricultural land uses are more likely to contain nitrogen 

sources such as septic systems, fertilizer, and manure than 

forested, grassland, and wetland land uses. The type of 

subsurface geochemical environment tapped by the wells 

is perhaps the dominant control on nitrate concentrations 

in groundwater (fig. 27C). Many wells in the county tap 

“strongly reducing” subsurface environments that are not 

favorable to the persistence of nitrate, regardless of the type 

of upgradient land use. This will be discussed in more detail 

in the Naturally Occurring Geochemical Processes in the 

Subsurface section of this report. 

Sulfate.—A single Berea well in Bainbridge Township 

(GE-122, appendix fig. 4–1) produced water with sulfate 

concentrations greater than 500 mg/L during two consecutive 

sampling rounds (fig. 24D). Although greater concentrations 

of sulfate occur in the southwestern part of the county, based 

on poor to fair but significant correlations of sulfate to 

latitude (rho = −0.28, p-value = 0.0002) and longitude 

(rho = 0.19, p-value = 0.0371) for 116 samples collected by 

the USGS during 1978–2009, concentrations above 500 mg/L 

are atypical. Concentrations of sulfate tend to decrease with 

depth below land surface (fig. 24D). This does not appear to 

be caused by changes in geochemical conditions with depth, 

because many of the samples throughout the entire depth 

interval shown in fig. 24D—even samples with elevated 

sulfate concentrations (greater than 70 mg/L)—are from an 

environment conducive to the transformation of sulfate to 

sulfide.

0

10

20

30

40

50

60

0 10 20 30 40 50 60

Turbidity, in nephelometric turbidity units

Total coliform bacteria, in colonies per 100 milliliters

Total coliform

Iron-sulfate-reducing water

Spearman’s rho = 0.66

p-value - 0.0056

Number of samples = 16

Visible turbidity

GE-141

Figure 26. Concentration of total coliform 

bacteria as a function of turbidity for samples 

collected by the U.S. Geological Survey from 

domestic wells, Geauga County, Ohio, 2009.
Groundwater Quality 55

0

0.4

0.8

1.2

1.6

2.0

0 20 40 60 80 100

Nitrate concentration, in milligrams per liter

Percent developed plus agricultural land use upgradient from well

Oxic

Manganese reducing

Strongly reducing

GE-341 Type of subsurface 

 geochemical environment 

0

0.4

0.8

1.2

1.6

2.0

A

B

C

0 20 40 60 80 100

Nitrate concentration, in milligrams per liter

Percent agricultural land use upgradient from well

GE

GE-85A

GE-85A

GE-332

GE-332

GE-85A

GE-332

-341

0

0.4

0.8

1.2

1.6

2.0

0 20 40 60 80 100

Nitrate concentration, in milligrams per liter

Percent developed land use upgradient from well

GE-341

Figure 27. Relation of nitrate concentration to environmental 

characteristics for samples collected by the U.S. Geological Survey 

in Geauga County, Ohio, 2009. A, Percent agricultural land use. B, 

Percent developed upgradient land use. C, Subsurface geochemical 

environment. 

Sulfate concentrations in the 16 domestic wells 

sampled by USGS in 2009 were not significantly correlated 

with population or developed land use. Absence of 

correlation of sulfate to constituents indicative of septic 

leachate (table 11, item 6) or percent agricultural land 

use suggests that these sources (along with biosolidsand septage-spreading on agricultural fields) may not be 

important sources of sulfate to groundwater in Geauga 

County. A more likely source of sulfate is combustion 

of fossil fuels. Combustion of fossil fuels releases sulfur 

dioxide to the atmosphere that combines with water to 

produce sulfate ions and acidity in rainfall, “especially 

in air masses that have encountered metropolitan areas” 

(Edwards and others, 2011). Northeastern Ohio is an area 

of acidic rainfall (U.S. Geological Survey, 2014) and a high 

rate of atmospheric sulfate deposition relative to much of 

the United States (Burns and others, 2011). Atmospheric 

deposition may account for the trend of increasing sulfate 

concentration and decreasing pH during 1978–2009 in 

groundwater samples from the Cuyahoga Group (table 9). 

Activities Affecting Pesticide and VOC Concentrations 

The paucity of pesticide and VOC detections in 

Geauga County means that either (a) human activities have 

generally not added these constituents to the groundwater, 

(b) drain tiles in agricultural areas have diverted infiltrating 

pesticides from groundwater to streams, or (c) pesticides 

and VOCs reaching the groundwater system have not 

persisted. As in the national study (Gilliom and others, 

2006) that found pesticides in groundwater primarily in 

agricultural and urban areas, the only pesticides detected in 

Geauga County were in water from domestic well GE-341, 

which has an upgradient land use of approximately 92 

percent agricultural—the highest of any well sampled (fig. 

27A and appendix table 3–1). Depth to groundwater in 

well GE-341 is very shallow (less than 10 ft below land 

surface), adding to its vulnerability. 

Results of VOC sampling in Geauga County were 

consistent with a national study of VOC occurrence in 

groundwater (Zogorski and others, 2006) that found urban 

land use to be one of the factors most commonly associated 

with VOCs in groundwater and also found more frequent 

VOC detections in samples from public-supply wells 

than from domestic wells. VOC detections were tabulated 

for samples from 31 domestic wells and 7 public-supply 

well fields in Geauga County (appendix table 4–3). Only 

one VOC—total xylenes—that was not a chlorination 

byproduct was detected at a very low concentration in 1 out 

of 31 samples collected at the Lake Lucerne public-supply 

well field. This well field has the most densely populated 

and developed upgradient land use of any well analyzed for 

the current study (fig. 28). 
56 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Activities Affecting Bromide and Organic Carbon 

Concentrations

Processes affecting the decrease in concentration of 

bromide in groundwater from 1986 to 2009 (table 9) are not 

readily apparent. Like chloride, bromide concentrations are 

greatest in wells with depth to groundwater less than about 

50 ft below land surface (fig. 29), suggesting a surface source 

for much of the bromide. Because bromide is associated with 

sources of salinity (and particularly with brines produced 

during oil and gas drilling), it is perplexing that bromide has 

decreased during a period in which chloride concentrations 

were stable (table 9). One possibility for this relation is that 

a decrease in the amount of oil-field brine at land surface 

(caused by either [a] the shift from storing brine in earthenbermed reserve pits to disposing of it in Class II injection 

wells in 1986, or [b] an undocumented reduction in the 

amount of brine spread on roads) has caused a decrease in 

brine infiltration to shallow groundwater that was concurrent 

with the increase in road-salt use documented in figure 10. 

This would have resulted in unchanging or increasing chloride 

concentrations while chloride:bromide ratios increased and 

bromide concentrations decreased. This process would be 

consistent with changes in groundwater quality from 1986 

to 2009 (tables 8 and 9) and with the observation that well 

GE-165, site of both the highest bromide concentration 

and the greatest decrease in concentration from 1999 to 

2009 (from 0.21 mg/L to 0.11 mg/L, fig. 30), is in Auburn 

Township (fig. 5) where brines are spread on roads. However, 

widespread inputs of oil-field brines to wells in the county 

have not been identified by use of chloride:bromide ratios 

(table 11 and fig. 25). 

Another possible explanation for the decrease in bromide 

concentrations in groundwater over time is the phaseout of 

leaded gasoline, beginning in the mid-1970s, which contained 

the additive ethylene dibromide (U.S. Environmental 

Protection Agency, 2013). Ethylene dibromide was also used 

in the past as a fumigant in vegetable and grain crops and on 

turf. The USEPA banned its use as a soil and grain fumigant in 

1984. Ethylene dibromide was analyzed for in samples from 

the ASM International public-supply well on nine different 

dates during 1995–2009, but it was never detected (appendix 

table 4–3); data predating the leaded gasoline phaseout were 

not examined for this report and so cannot be used to test this 

theory. However, distance of well from road is not uniformly 

related to the magnitude of bromide concentration decrease 

that was observed from 1999 to 2009 in domestic wells 

(fig. 30). 

The reason for the decline in dissolved organic carbon 

concentrations during 1978–2009 (tables 8B and 9) is 

unknown. Declines were seen in all aquifers except the 

glacial deposits. The relatively short timeframe for the decline 

(decades) suggests it may be caused by some change in human 

activities rather than by a geologic process.

0

20

40

60

80

100

120

140

160

180

200

0 20 40 60 80 100

Population updragient of well in year 2000

Percent developed land use upgradient of well in 2001

Domestic wells 

Public-supply 

 well fields Christ Presbyterian

GE-332

Burton

Middlefield

Chardon

Lake Lucerne

Tanglewood Lake

ASM International

Figure 28.

EXPLANATION

Figure 28. Population and percent developed land use upgradient of public-supply well 

fields considered in this report and domestic wells sampled in 2009, Geauga County, Ohio. 

(Public-supply well data source is listed in table 4, domestic wells are listed in table 3, and 

land-use and population data are in appendix 3.)
Groundwater Quality 57

0

20

40

60

80

100

120

140

0 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40

Depth to water, in feet below land surface

Bromide concentration, in milligrams per liter

Spearman's rho = -0.22

p-value = 0.0408

Number of samples = 83

Figure 29. Concentration of 

bromide as a function of depth to 

water in wells sampled by the U.S. 

Geological Survey, Geauga County, 

Ohio, 1986–2009.

0

0.05

0.10

0.15

0.20

0.25

0 0.05 0.10 0.15 0.20 0.25

2009 bromide concentration, 

in milligrams per liter

1999 bromide concentration, in milligrams per liter

No change

No data

<100

101 to 200

>200

Located in a township 

 where brines are 

 spread on roads

GE

Higher in 2009

Higher in 1999

-165

Distance of well from road, 

 in feet 

EXPLANATION

Figure 30. Changes from 1999 to 2009 in bromide concentrations as a function of distance of well from 

road for wells sampled by the U.S. Geological Survey, Geauga County, Ohio.

Naturally Occurring Geochemical Processes in 

the Subsurface

Naturally occurring processes occurring in the subsurface that influence the quality of groundwater in Geauga 

County include evolution of groundwater along a flow path, 

ion-exchange reactions with aquifer sediments, and oxidationreduction (redox) reactions. These processes can cause some 

of the observed differences in water chemistry between 

aquifers described by Jagucki and Darner (2001). Jagucki 

and Darner found that, of the four aquifers, the majority of 

statistically significant differences in constituent concentrations occurred between the Pottsville Formation and the Berea 

Sandstone.
58 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Evolution of Groundwater Along a Flow Path

Many of the observed differences in chemistry between 

aquifers are related to the amount of time that groundwater 

in the aquifer has been in contact with subsurface rocks and 

sediments (also known as “groundwater residence time”). In 

general, the longer the distance that the groundwater has traveled from the water table (depicted by length of flow lines on 

figures 1 and 2), the longer the residence time of groundwater 

in the aquifer and the greater the amount of minerals that will 

have been dissolved from aquifer rocks into groundwater. In 

the hilly topography of Geauga County, groundwater flows 

along short, isolated flow paths that originate at the hilltops 

(which are capped by the Pottsville Formation and a thin cover 

of glacial deposits) and travel downward and laterally (figs. 1A

and 2). Water in the Pottsville Formation entered the aquifer 

relatively recently and thus has had limited contact time with 

aquifer materials. As a result, samples from the Pottsville 

Formation generally have lower concentrations of many dissolved constituents than samples from the Berea Sandstone 

(fig. 31A–K). Much of the groundwater that reaches the Berea 

Sandstone has traveled downward from the Pottsville Formation and through the Cuyahoga Group. Water in the Berea 

Sandstone and lower Cuyahoga Group has generally been in 

contact with aquifer rocks for decades or centuries, according 

to simulations by Eberts and others (1990) (fig. 2), dissolving 

and sometimes precipitating aquifer minerals. 

In Geauga County, the residence time of groundwater 

withdrawn from a particular well relative to that withdrawn 

from other wells is best approximated by the elevation of the 

well bottom (rather than to depth of well measured as feet 

below land surface), because of the hilly topography and 

strong downward component of groundwater flow in the area. 

(Elevation of well bottom becomes a less reliable approximation for groundwater residence time at lower elevations once 

water reaches the Berea Sandstone, where flow is largely 

lateral, and on the eastern edge of the county, where flow in 

the Cuyahoga Group is predominantly lateral [fig. 2]). The 

relation of tritium concentration to well-bottom elevation 

(fig. 31L) provides evidence that groundwater age (and thus 

groundwater residence time) generally increases at lower 

elevations. Tritium, a radioactive isotope of hydrogen, is an 

age tracer that was analyzed for in several of the groundwater 

samples collected in 1999 (Jagucki and Darner, 2001) and 

in two additional samples from the Berea Sandstone in 2009 

(appendix table 4–1). Concentrations of tritium in precipitation of northeastern Ohio, 1953–1983, were estimated by 

Michel (1989). Michel found that tritium concentrations in 

precipitation increased substantially after 1953 as a result of 

nuclear weapons testing. Concentrations peaked in 1963 and 

then declined to about 22–48 picocuries per liter8 (pCi/L) by 

2009 (R.L. Michel, U.S. Geological Survey, written commun., 

2008). Jagucki and Darner (2001) adjusted Michel’s precipitation data to account for radioactive decay of tritium that would 

have happened between the time the preciptation occurred 

8

 22–48 pCi/L = 7–15 tritium units (TU).

and 1999. This allowed them to determine when samples 

of groundwater collected in 1999 had originally entered, or 

recharged, the aquifer system based on tritium analyses. These 

calculations showed that “old” groundwater in northeastern 

Ohio that recharged prior to 1953 would have a low tritium 

concentration (less that 5.7 pCi/L9) in 1999; “young” water 

that recharged after 1953 would have a tritium concentration greater than 5.7 pCi/L in 1999 as long as there had not 

been substantial mixing of young and old water within the 

aquifer (Jagucki and Darner, 2001). A plot of all tritium data 

collected in Geauga County as a function of well elevation 

(fig. 31L) shows that, in general, samples from wells with a 

bottom elevation above about 1,050 ft and completed in either 

the Pottsville Formation or the Cuyahoga Group contained 

tritium at concentrations greater than 5.7 pCi/L in 1999 and 

are indicative of young water. Conversely, most samples from 

wells with a bottom elevation lower than 1,050 ft and completed in the Berea Sandstone had low tritium concentrations 

in 1999 that are indicative of old water. Some wells completed 

in the glacial deposits and located in buried valleys at low 

elevations likely receive a mix of young and old water that has 

discharged from all bedrock units and thus contain intermediate concentrations of tritium. 

 Several constituents and properties had a statistically 

significant (p <0.05) and good to fair negative correlation 

to elevation of well bottom (meaning that concentrations 

increase at lower elevations). In order of decreasing correlation strength, these are ammonia, pH, boron, sodium, fluoride, 

alkalinity, sulfide, specific conductance, dissolved solids, 

potassium, and silica (fig. 31). Silica and potassium are common in sedimentary rocks, as are lesser amounts of fluoride 

and boron. The concentration of dissolved solids represents 

the concentration of ions dissolved in groundwater; specific 

conductance is another measure of dissolved ion concentration. Logically, all of the listed chemical constituents would 

increase in concentration along a groundwater flow path as 

mineral dissolution increases. Because pH and alkalinity 

increase as a result of dissolution reactions, values of these 

properties also tend to increase with increased groundwater 

residence time. Ammonia and sulfide concentrations are likely 

related to redox reactions (see later section) that can also be a 

function of flow-path length. 

Ion-Exchange Reactions With Aquifer Sediments

Ion exchange is a natural process in the subsurface that 

has a substantial effect on sodium concentrations in water 

produced by wells in Geauga County. Sodium concentrations 

of groundwater samples in the county are related primarily 

to the geologic formation in which the well is completed. Six 

of the 16 samples collected in 2009 from domestic wells had 

sodium concentrations that exceeded health-based benchmarks 

(appendix table 4–1 and table 5); these six samples were 

from wells completed in either the Cuyahoga Group or the 

underlying Berea Sandstone, both of which were deposited 

9

 5.7 pCi/L = 1.8 TU.
Groundwater Quality 59

Glacial deposits

Pottsville Formation

Cuyahoga Group

Aquifer

Berea Sandstone

EXPLANATION

A

800

850

900

950

1,000

1,050

1,100

1,150

1,200

1,250

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

Elevation of well bottom, in feet

Ammonia concentration, in milligrams per liter

B

rho = -0.62

p-value = <0.0001 

n = 107

rho = -0.55

p-value = <0.0001 

n = 106

800

850

900

950

1,000

1,050

1,100

1,150

1,200

1,250

4 5 6 7 8 9 10

Elevation of well bottom, in feet

pH, in standard units

C

SMCL upper limit

SMCL lower limit

rho = -0.51

p-value = 0.0041 

n = 30

800

850

900

950

1,000

1,050

1,100

1,150

1,200

1,250

0 200 400 600 800 1,000 1,200 1,400

Elevation of well bottom, in feet

Boron concentration, in milligrams per liter

D

800

850

900

950

1,000

1,050

1,100

1,150

1,200

1,250

0 50 100 150 200 250 300 350

Elevation of well bottom, in feet

Sodium concentration, in milligrams per liter

Drinking water 

advisory level

rho = -0.49

p-value = <0.0001 

n = 107

Figure 31. Relation of selected constituent concentrations to elevation of well bottom for samples collected by the U.S. Geological 

Survey, Geauga County, Ohio, 1978–2009. (Rho is Spearman’s rho correlation coefficient; p-value is statistical significance of correlation; 

n is number of samples; SMCL is Secondary Maximum Contaminant Level.)
60 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Glacial deposits

Pottsville Formation

Cuyahoga Group

Aquifer

Berea Sandstone

EXPLANATIONElevation of well bottom, in feet

800

850

900

950

1,000

1,050

1,100

1,150

1,200

1,250

0 50 100 150 200 250 300 350 400

Alkalinity, in milligrams per liter

rho = -0.45

p-value = <0.0001 

n = 107

F

800

850

900

950

1,000

1,050

1,100

1,150

1,200

1,250

0 500 1,000 1,500 2,000 2,500 3,000

Elevation of well bottom, in feet

Specific conductance, in microsiemens per centimeter

H

rho = -0.25

p-value = 0.0092

n = 105

800

850

900

950

1,000

1,050

1,100

1,150

1,200

1,250

0 0.2 0.4 0.6 0.8 1.0 1.2

Elevation of well bottom, in feet

Sulfide concentration, in milligrams per liter

rho = -0.31

p-value = 0.0170 

n = 57

G

E

800

850

900

950

1,000

1,050

1,100

1,150

1,200

1,250

0 0.2 0.4 0.6 0.8 1.0 1.2

Elevation of well bottom, in feet

Fluoride concentration, in milligrams per liter

rho = -0.47

p-value = <0.0001 

n = 77

Figure 31. Relation of selected constituent concentrations to elevation of well bottom for samples collected by the U.S. Geological 

Survey, Geauga County, Ohio, 1978–2009. (Rho is Spearman’s rho correlation coefficient; p-value is statistical significance of correlation; 

n is number of samples; SMCL is Secondary Maximum Contaminant Level.)—Continued
Groundwater Quality 61

Figure 31. Relation of selected constituent concentrations to elevation of well bottom for samples collected by the U.S. Geological 

Survey, Geauga County, Ohio, 1978–2009. (Rho is Spearman’s rho correlation coefficient; p-value is statistical significance of correlation; 

n is number of samples; SMCL is Secondary Maximum Contaminant Level.)—Continued

Glacial deposits

Pottsville Formation

Cuyahoga Group

Aquifer

Berea Sandstone

EXPLANATION

I

800

850

900

950

1,000

1,050

1,100

1,150

1,200

1,250

0 200 400 600 800 1,000 1,200 1,400 1,600 1,800

Elevation of well bottom, in feet

Dissolved solids concentration, in milligrams per liter SMCL

rho = -0.25

p-value = 0.0132

n = 96

J

rho = -0.25

p-value = 0.0092

n = 107

800

850

900

950

1,000

1,050

1,100

1,150

1,200

1,250

0 1 2 3 4 5 6 7

Elevation of well bottom, in feet

Potassium concentration, in milligrams per liter

800

850

900

950

1,000

1,050

1,100

1,150

1,200

1,250

0 5 10 15 20 25

Elevation of well bottom, in feet

Silica concentration, in milligrams per liter

rho = -0.24

p-value = 0.0121

n = 107

K

800

850

900

950

1,000

1,050

1,100

1,150

1,200

1,250

0 20 40 60 80 100

Elevation of well bottom, in feet

Tritium concentration in 1999, in picocuries per liter

(Tritium concentrations for samples collected in 2009 have been 

corrected for radioactive decay so that they reflect 

concentrations in 1999, when the majority of samples were collected.)

Old water

(Pre-1953

recharge) 

Young water

(Post-1953

recharge) 

GE-202

GE-108

rho = 0.48

p-value = 0.0617

n = 16

L
62 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

in a marine (saltwater) environment. In these two formations, 

sodium that adsorbed to clays at the time of aquifer deposition 

migrates into groundwater as calcium and magnesium 

cations move from groundwater to adsorption sites on clays 

in a process known as cation exchange. One result of cation 

exchange is the enrichment of sodium concentrations in 

samples from many wells completed in the Cuyahoga Group 

and the Berea Sandstone. The median sodium concentration 

for all samples from Cuyahoga Group and Berea Sandstone 

wells during 1978–2009 was 56.9 mg/L, compared to a 

median of 7.74 mg/L for samples from wells completed in the 

glacial deposits and Pottsville Formation, which were at least 

partially deposited in a nonmarine (terrestrial) environment. 

Sodium concentrations exceeding health-based 

benchmarks (for people limiting sodium intake) were 

measured in some samples from public-supply wells (tables 4 

and 5) that were completed in all four aquifers, likely because 

public-supply wells pump at higher rates than domestic wells 

(2,040–385,000 gallons per day [gal/d] for public-supply wells 

with untreated sodium data [table 4]) compared to estimated 

pumping rates of about 600 gal/d for domestic wells serving a 

four-person household). Public-supply wells therefore draw in 

water from larger areas than domestic wells, potentially from 

surrounding formations, and more readily mobilize sodiumrich water to move along preferential flow paths that may be 

present (such as fractures, abandoned wells, and well bores) 

(Landon and others, 2009).

Oxidation-Reduction Reactions

Microbial respiration causes many chemical reactions to 

occur that can greatly affect the concentration in groundwater 

of some constituents that are present naturally in aquifer 

rocks and sediments. These reactions—called oxidationreduction, or redox, reactions—also influence the fate of some 

manmade contaminants that enter the groundwater system. 

Redox reactions readily occur when organic carbon is present 

in the aquifer. During these reactions, microbes will transfer 

electrons from organic carbon sequentially to the following 

“electron acceptors” (listed in order of preference): dissolved 

oxygen, nitrate, manganese (IV), iron (III), sulfate, and carbon 

dioxide. After one electron acceptor is consumed, microbes 

will then use the next most favorable electron acceptor 

and the redox condition of the groundwater will become 

more “reducing.” On the basis of measured concentrations 

of dissolved oxygen, nitrate, manganese, iron, sulfate in a 

groundwater sample, the redox process(es) occurring in the 

part of the aquifer from which the sample is derived can be 

categorized according to the criteria listed in table 12. Redox 

conditions were characterized for 116 samples from 65 wells 

sampled by USGS in Geauga County during 1978–2009. 

These conditions are summarized in table 12 and listed by 

individual well in appendix table 5–1. Ideally, iron-reducing 

conditions would be distinguished from sulfate-reducing 

conditions, because some constituents behave differently 

in the two environments. However, for this study, iron- and 

sulfate-reducing waters are combined for the purposes of 

discussion and referred to as “strongly reducing” because 

the majority of samples either lacked sulfide data, which is 

required to distinguish between these two conditions, or did 

not have dissolved iron:sulfide ratios of sufficient magnitude 

to distinguish between the two processes. 

Most groundwater samples were either strongly reducing 

(60 percent) or oxic (18 percent) (table 12). No samples were 

methanogenic, which is the most reducing redox process 

whereby transfer of electrons converts carbon dioxide gas 

and hydrogen ions in groundwater into methane. Each redox 

condition is associated with specific contaminants in Geauga 

County groundwater (table 12). Strongly reducing (iron- and 

[or] sulfate-reducing) waters contained many of the naturally 

occurring contaminants—arsenic, manganese, and iron—

found to exceed health-based and aesthetically based drinkingwater standards. Strongly reducing conditions are a common 

geochemical trigger that releases arsenic from aquifer 

sediments into groundwater (Smedley and Kinniburg, 2002).

This seems to be the process controlling arsenic concentrations 

in Geauga County groundwater, where the six oxic, suboxic, 

nitrate-reducing, and manganese-reducing groundwater 

samples for which arsenic analyses were available were 

associated with low concentrations of arsenic (less than or 

equal to 1 μg/L), whereas arsenic concentrations in the 12 

strongly reducing samples ranged from less than 1 to 15 μg/L, 

with a median concentration of 4 μg/L. 

Nitrate was detected primarily in oxic and nitratereducing waters—redox conditions that occur only in the 

Pottsville Formation and Berea Sandstone. Infiltrating 

precipitation may encounter nitrate sources near land surface. 

Nitrate in water that recharges the aquifer system will 

persist in groundwater in oxic areas but will eventually be 

converted to ammonia and harmless nitrogen gas in nitratereducing environments or in waters that have more reducing 

conditions (see arrow, table 12). Nitrate concentrations greater 

than 1 mg/L are found almost exclusively in water from the 

Pottsville Formation10 (appendix table 4–1); wells tapping the 

Pottsville Formation have bottom elevations higher than 1,075 

ft (fig. 31). Ammonia concentrations greater than 0.2 mg/L 

generally occur at elevations below 1,075 ft (fig. 31A).

VOCs found to be associated with specific redox 

conditions in a nationwide study (Zogorski and others, 2006) 

are listed in table 12. Only VOCs that have also been found 

in groundwater during Ohio EPA investigations of chemical 

releases in Geauga County (fig. 11) are included. VOCs are 

likely to persist and thus be detected more frequently in redox 

conditions in which they degrade slowly (Zogorski and others, 

2006). In the absence of remediation, the persistence of VOCs 

released at some of the known groundwater contamination 

sites in the county (fig. 11) will be affected by the redox 

10 The exception to this statement is well GE-341 in Thompson Township, 

which is completed in the Cuyahoga Group. Samples from well GE-341 have 

a mixed oxic-manganese-reducing redox condition and contain 1.38–1.73 

mg/L of nitrate as N. The well bottom elevation is 1,147 ft.
Groundwater Quality 63

Table 12. Redox conditions in groundwater samples collected by the U.S. Geological Survey during 1978–2009 in Geauga County, Ohio, threshold criteria, and associated contaminants.[Criteria for inferring redox condition are from Jurgens and others, 2009. VOCs likely to persist in each redox condition are based on nationwide findings by Zogorski and others (2006). Abbreviations: n, total number of samples; mg/L, milligram per liter; μg/L, microgram per liter; Fm, Formation; —, criteria do not apply because the species concentration is not affected by the redox process; ≤, less than or equal to; ≥, greater than or equal to; <, less than; >, greater than; ND, no data; TCA, 1,1,1-trichloroethane; TCE, trichloroethene; PCE, perchloroethene]

Redox 

condition

Percent of 

groundwater 

samples1

(n=116)

Occurrence 

Criteria for inferring redox environment from 

water-quality data Contaminants associated with each 

redox condition in Geauga County 

groundwater

VOCs likely 

to persist 

in each 

redox 

condition 

Dissolved 

oxygen 

(mg/L)

Nitrate, 

as 

nitrogen 

(mg/L)

Manganese 

(μg/L)

Iron 

(μg/L)

Sulfate 

(mg/L)

More reducing

Oxic2 18 Pottsville Fm, 

Berea Sandstone (near buried valleys)

≥0.5

— <50 <100

— Nitrate (detected in all oxic waters in the Pottsville 

Fm at concentrations of 0.38 to 6.0 mg/L; detected in one of the three oxic groundwater samples from the Berea Sandstone at an estimated concentration of 0.03 mg/L)

TCA, TCE, PCE, 

bromodichloromethane, and chloroform

Suboxic 6 Glacial deposits, 

Cuyahoga Group, Berea Sandstone

<0.5 <0.5 <50 <100

— Nitrate (detected in water from one 

Berea Sandstone well at a concentration of 0.47 mg/L)

Gasoline 

hydrocarbons including benzene and toluene

Nitrate 

reducing

5 Pottsville Fm <0.5 ≥0.5 <50 <100

— Nitrate (detected at concentrations of 

0.54 to 2.9 mg/L)

Manganese 

reducing3

3 Cuyahoga 

Group, glacial deposits

<0.5 <0.5 ≥50 <100

— Manganese at concentrations exceeding 

the aesthetically based drinking-water standard

Strongly 

reducing (iron and [or] sulfate reducing)4

60 All four 

aquifers at all elevations

<0.5 <0.5

— ≥100 ≥0.5 Arsenic at concentrations exceeding the 

health-based standard in some samples

Iron at concentrations exceeding the aesthetically 

based standard in 83% of samples

Manganese at concentrations exceeding the healthbased standard in 7% of samples and the 

aesthetically based standard in 73% of samples

Hydrogen sulfide gas and (or) precipitation of iron 

sulfide minerals in sulfate-reducing zones

Methanogenic

0 Did not occur <0.5 <0.5

— ≥100 <0.5 ND

1 Sample percentages do not add up to 100 because 8 % of samples were mixed oxic/strongly reducing. These samples had constituent concentrations characteristic of both redox conditions and 

occurred in all four aquifers.

2Includes waters that are likely oxic—samples in which dissolved oxygen was not measured (this was not done consistently prior to 1999) but that have other constituent concentrations consistent with 

an oxic environment.

3Includes waters that are mixed oxic/manganese reducing. In these mixed samples, manganese and iron concentrations are consistent with manganese-reducing waters, but dissolved oxygen is present at 

concentrations greater than 0.5 mg/L.

4Includes waters that were not analyzed for dissolved oxygen but that have other constituent concentrations consistent with a strongly reducing environment.
64 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

condition of groundwater beneath these sites. (However, redox 

conditions at these sites have not been categorized by USGS 

personnel.)

Knowing that redox conditions control the occurrence of 

many contaminants, attempts were made to further document 

spatially where oxic and strongly reducing redox conditions 

were found so that contaminant occurrence can be better 

anticipated by planners and well owners. Also, because 

some, but not all, strongly reducing groundwater samples 

contained (a) arsenic and manganese at concentrations that can 

adversely affect human health or (b) sulfide at concentrations 

that could adversely affect drinking-water aesthetics, factors 

were investigated that could be used to predict where these 

exceedances are likely to occur. To that end, the following 

questions were considered:

Can areas where oxic conditions and strongly 

reducing conditions occur be better delineated? Because 

two of the aquifers—the Pottsville Formation and the Berea 

Sandstone—are oxic in some areas and strongly reducing in 

others, an effort was made to further define spatially where 

different redox conditions occur. First, redox conditions in 

the Pottsville Formation were examined. Because oxygen 

in groundwater is derived from infiltrating precipitation, 

various measures of well construction that might approximate 

nearness of the sampling interval to recently recharged 

groundwater were plotted, using color codes to indicate redox 

conditions. Surprisingly, a visual inspection of plots (data 

not shown in report) showed no relation of redox condition 

of samples from the Pottsville Formation to well-bottom 

elevation, depth of well, depth to water, or feet of water above 

open interval; strongly reducing samples originated from all 

elevations and depths. Similarly, a map showing the spatial 

distribution of redox conditions in the Pottsville Formation 

(fig. 32) showed no relation of redox condition to well position 

along a groundwater flow path (recharge area, mid flow path, 

or discharge area). Instead, it seems that redox conditions at 

a well location were affected by the permeability of rock and 

sediments overlying the Pottsville Formation in the vicinity of 

the well. Wells tapping strongly reducing groundwater tended 

to have a greater thickness of overlying low-permeability 

material (such as clay or shale) than wells tapping oxic or 

nitrate-reducing groundwater (fig. 33). In general, wells with 

more than about 30 ft of overlying clay or shale produced 

strongly reducing water. The presence of shale overlying the 

Pottsville Formation was particularly diagnostic—about 30 

percent of the strongly reducing samples were from areas 

overlain by shale, but none of the oxic or nitrate-reducing 

samples were. Low-permeability clay and shale inhibit 

recharge, leading to lower oxygen content and, consequently, 

more reduced waters. Clay and shale may also have higher 

organic carbon content than the sandstones of the Pottsville 

Formation, which would stimulate oxygen consumption and 

drive the redox environment toward reducing conditions. 

Available water-quality data indicate that strongly 

reducing conditions are more prevalent in the Pottsville 

Formation in the southeastern corner of the county (fig. 

32), and oxic and nitrate-reducing conditions (along with 

detectable nitrates in groundwater) are more prevalent in 

the western townships. The distribution of shale layers 

in and overlying the Pottsville Formation may cause this 

spatial pattern. Preliminary mapping data suggest that such 

shales are thicker than average near the center of Burton 

Township, are discontinuous beneath Middlefield Township, 

and are relatively commonplace beneath Troy and Parkman 

Townships, where they cause yields of wells tapping the 

Pottsville Formation to be lower than elsewhere in the 

county (Baker, 1964). In other townships, shale layers in and 

overlying the Pottsville Formation are thin and discontinuous 

because of erosion. 

Next, redox conditions in the Berea Sandstone were 

examined. Finding oxic groundwater in the Berea Sandstone 

was unexpected because the Berea Sandstone is the deepest aquifer in the county and contains water that has been in 

the aquifer system for the longest period of time (fig. 2). The 

redox state of water from Berea wells was examined relative 

to locations of the wells. Three of the four Berea Sandstone 

wells that have produced oxic or suboxic samples are very 

near areas where the Berea Sandstone crops out (that is, where 

it occurs at land surface) or is covered by glacial sediments 

filling an ancestral stream valley, as mapped by Eberts and 

others (1990, plate 1). Strongly reducing wells are farther from 

these outcrop areas, but not so far as to be in areas overlain 

by shales of the Cuyahoga Group. In wells producing oxic to 

suboxic water, either depth to groundwater was shallow (less 

than 45 ft below land surface) or the measured water level was 

within the open interval (uncased portion) of the well. Wells 

tapping strongly reducing groundwater had depths to water 

greater than 60 ft and measured water levels of 15 ft or more 

above the open interval of the well. 

In summary, it may be of interest to planning officials 

and (or) homeowners to know whether groundwater in areas 

underlain by sandstone is likely to be oxic (a geochemical environment where nitrate and chlorinated VOCs such 

as TCE and PCE are likely to persist) or strongly reducing 

(an environment where dissolved arsenic may be present at 

concentrations above the health-based benchmark and where 

gasoline hydrocarbons, such as benzene and toluene, are likely 

to persist). Clues to the groundwater redox condition may be 

provided by drillers’ well logs (available online at https://apps.

ohiodnr.gov/water/maptechs/wellogs/appNEW/Default.aspx) 

used in conjunction with land-surface elevation data from a 

topographic map. Well-bottom elevation can be determined 

by subtracting total well depth from land-surface elevation. If 

the well is open to (uncased through) a sandstone aquifer and 

the well-bottom elevation is greater than about 1,075 ft, the 

well is likely completed in the Pottsville Formation (fig. 31). 

If the log for such a well shows 30 ft or more of clay or shale 

overlying the sandstone aquifer, groundwater is likely to be 

strongly reducing (fig. 33)—particularly if shale is present. If 

the well-bottom elevation is between about 850 and 1,025 ft 

(fig. 31) and the well is open to a sandstone aquifer, it is the 

Berea Sandstone. For Berea wells, if the static water level 
Groundwater Quality 65

Chagrin River

Cuyahoga River

Grand River

GE-23

GE-95

GE-92

GE-89

GE-73

GE-69

GE-68

GE-61

GE-60

GE-39

GE-34

GE-355

GE-332

GE-202

GE-119 GE-85A

GE-81Q

GE-204

GE-18Q

GE-180

GE-151

GE-115

GE-112

GE-111

GE-109

GE-349A

1150

1150

1100

1200

1000

950

1250

1250

950

1100

1250

1100

1000

1050

1100

1200

1050

1150

1200

1150

1050

1200

1200

1150

1000

1050

1200

1100

1200

1200

1050

1250

1200

Troy

Auburn

Burton Russell

Munson

Newbury

Chardon

Parkman

Chester Claridon

Montville

Thompson

Bainbridge

Hambden

Huntsburg

Middlefield

81°10'

81°20'

41°30'

41°40'

Cleveland

Figure 32.

Base from U.S. Geological Survey

1:24,000 digital data

Universal Transverse Mercator, zone 17

Water-table contours modifiedfrom Jagucki and Lesney, 1995

Land cover from Homer and others, 2007

Biosolids data modified from Ohio 

0 5 MILES Environmental Protection Agency, 2010a

0 5 KILOMETERS

EXPLANATION

Potentiometric surface—Glacial deposits and 

 Pottsville Formation

Water-table contour—Shows elevation of water table. 

Dashed where inferred. Contour interval 50 feet.

Generalized direction of groundwater flow

Fields approved for biosolids application

Developed land cover, 2001

Agricultural land cover, 2001

Nitrate concentration for wells in Pottsville Formation 

 (milligrams per liter)

Oxic and nitrate-reducing wells

0.18–0.99

1.0–2.99

3.0–6.0

Iron and (or) sulfate-reducing wells

< 0.18

0.18–0.99

1.0–2.99

of potential sources of nitrate near land surface. 

Figure 32. Redox condition of wells tapping the Pottsville Formation, 1978–2009, relative to groundwater flow and locations 
66 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Figure 33. 

20

40

60

80

0

100

Groundwater redox condition

(5) (7) (7)

Thickness of clay and shale overlying the Pottsville Formation, in feet

x

Oxic Nitrate reducing Strongly reducing

EXPLANATION

(7) Number of samples 

x

Upper adjacent value

75th percentile

Median

25th percentile

Upper outside value

Lower adjacent value

sampled well locations, 1978–2009.

Figure 33. Thickness of clay and shale overlying the Pottsville Formation in Geauga County, Ohio, by groundwater redox condition at 

listed on the well log is less than 45 ft below land surface or 

is within the uncased portion of the well, the redox condition 

of groundwater is likely to be oxic. If the static water level 

is greater than about 60 ft below land surface and is 15 ft or 

more above the bottom of the well casing, the groundwater is 

likely to be strongly reducing.

What factor(s) cause concentrations of arsenic in 

strongly reducing groundwater to exceed health-based 

benchmarks in some areas and not in others? To answer 

this question, strongly reducing waters in all aquifers were 

examined. Wells producing strongly reducing water that 

exceeds the health-based benchmark for arsenic (prior to 

treatment) included two domestic wells (GE-108 and GE-202) 

and public-supply wells in Middlefield Village and Chardon11

11 Public-supply wells in Middlefield and Chardon were sampled by the 

USGS in 1980 (wells GE-42 and GE-53Q, appendix table 4–1). USGS 

water-quality data for these wells were used to create figure 34; however, 

arsenic concentrations exceeding the human-health benchmark have also been 

documented by Ohio EPA water-quality monitoring programs at these wells 

(tables 4 and 5).

(fig. 34). Three of these wells tap the glacial deposits, and 

one well, GE-202, draws water from the Pottsville Formation. 

There is no evident spatial pattern to the wells with elevated 

arsenic that suggests that glacial sediments or bedrock in a 

particular area are arsenic enriched (fig. 34). Stratigraphic data 

from these four wells and statewide data (p. 33) indicate that 

arsenic occurs at concentrations exceeding the health-based 

benchmark more often in sand and gravel aquifers (which 

includes glacial deposits) than in sandstone aquifers (such as 

the Pottsville Formation or the Berea Sandstone). However, a 

literature review of arsenic concentrations in 32 compliance 

samples from public-supply wells in Bainbridge Township 

(Ohio Department of Natural Resources, 2008b) found that 

aquifer type was not a reliable risk factor. Although most 

groundwater samples considered by ODNR were below the 

health-based benchmark of 10 μg/L, at least one sample from 

each of the following formations exceeded health-based standards: the Pottsville Formation, the Cuyahoga Group (maximum concentration of 20 μg/L in both formations), and the 

Berea Sandstone (maximum concentration of 24 μg/L). 
Groundwater Quality 67

Troy

Russell Burton

Munson

Newbury

Parkman

Chester Claridon

Thompson

Bainbridge

Hambden

Huntsburg

Middlefield

Chagrin River

Cuyahoga River

Grand River

Middlefield

well field

GE-202

Chardon 

well field

GE-108

Auburn

Chardon

Montville

81°10'

81°20'

41°40'

41°30'

Figure 34.

Base from U.S. Geological Survey

1:24,000 digital data

Universal Transverse Mercator, zone 17

0 5 MILES

0 5 KILOMETERS

EXPLANATION

Redox process (see appendix table 5-1)—If the 

redox process has changed over time at a well, 

the top symbol represents the most recent 

sample.

Oxic, suboxic, or nitrate or manganese reducing

Mixed oxic-anoxic

Strongly reducing

Manganese concentration greater than 

300 micrograms per liter (μg/L)

Arsenic concentration greater than 10 μg/L

Cleveland

Figure 34. Locations of wells tapping a strongly reducing groundwater environment relative to locations of wells with 

samples that have exceeded the health-based benchmarks for arsenic or manganese, for wells sampled by the U.S. 

Geological Survey, Geauga County, Ohio, 1978–2009.
68 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Groundwater age (or time since water recharged the 

groundwater system) is a factor that has been found to influence arsenic concentrations in other study areas (Smedley and 

Kinniburg, 2002; Thomas, 2007). Thomas (2007) noted that 

for wells tapping the glacial aquifer system in the northern 

United States (which includes the glacial deposits in Geauga 

County), the likelihood of arsenic exceeding the health-based 

standard in strongly reducing water was increased if the water 

samples were old (pre-1953 recharge as indicated by lack of 

measureable tritium). Old groundwater can indicate sluggish 

groundwater flow. Smedley and Kinniburg (2002) suggested 

that slow-moving flow does not flush away arsenic after it is 

released from aquifer sediments, allowing it to accumulate in 

groundwater. Findings in Geauga County were consistent with 

those of Smedley and Kinniburg (2002) and Thomas (2007). 

Wells GE-108 and GE-202 are the only two wells completed 

in a formation other than the Berea Sandstone for which both 

arsenic and tritium data are available and for which tritium 

concentrations are indicative of pre-1953 recharge (fig. 31L). 

Well logs provide clues as to why these two wells would 

produce older water than other wells in the same aquifers. 

GE-202 is the only Pottsville well sampled in 2009 (the year 

all samples were analyzed for arsenic) at a location where the 

aquifer is overlain by shale, which likely inhibits recharge. 

GE-108 is one of the deepest glacial wells sampled (132 ft 

below land surface), and is overlain by 83 ft of clay, which 

would also limit recharge relative to other wells. Permeability 

of overlying materials seems to affect arsenic concentrations 

more than well construction, as there was no statistically significant relation of arsenic concentration to well depth or wellbottom elevation when considering the 22 arsenic samples 

collected by USGS personnel in the county (1978–2009) for 

which well-depth information was available (appendix table 

4–1). 

What factor(s) cause concentrations of manganese 

in strongly reducing groundwater to exceed health-based 

benchmarks in some areas and not in others? Only 5 out of 

70 strongly reducing samples collected by the USGS (appendix table 5–1) have historically (1978–1999) exceeded the 

health-based benchmark for manganese (300 μg/L) (appendix 

table 4–1). The small number of exceedances indicates that 

redox condition is not the sole process causing elevated manganese in groundwater. Four of the five samples with manganese concentrations above 300 μg/L are from wells clustered in Burton, Middlefield, and Parkman Townships in the 

southeastern part of the county (fig. 34); most of these wells 

produce water from the Pottsville Formation. In the past, Ohio 

EPA personnel investigated groundwater in southwestern Middlefield Township (Ohio Environmental Protection Agency, 

1995; Bolas and Mohr, 1995)—mostly in the Pottsville Formation—and concluded that elevated manganese in groundwater 

in this area is naturally occurring rather than caused by human 

contamination, with concentrations in samples from a total of 

28 wells ranging from less than 10 μg/L to as high as 4,060 

μg/L. Bolas and Mohr concluded that this “elevated pocket” of 

manganese in groundwater was due to reducing groundwater 

conditions plus one or all of the following: (1) the manganese 

content of the Pottsville Formation being higher here than in 

other areas of the county, (2) the manganese content of the glacial till overlying the Pottsville Formation being higher here 

than in other areas, and (3) the pH of groundwater in this area 

favoring the dissolution of manganese from aquifer sediments. 

The observation that manganese dissolves in acidic water and 

precipitates as water acidity is neutralized has been documented by other researchers (Hem, 1989). Of all 51 manganese-reducing or strongly reducing wells (or mixed oxic/

anoxic wells) sampled by the USGS in Geauga County having 

manganese concentrations less than 300 μg/L, the median pH 

was 7.2 (range 4.7–7.7). The median pH for the five wells with 

manganese concentrations greater than 300 μg/L was more 

acidic, at 6.6 (range 6.0–6.9). 

Can zones where hydrogen sulfide gas and iron sulfide 

precipitates are present be further delineated? Hydrogen 

sulfide gas and (or) iron sulfide precipitates occur in sulfatereducing conditions (a subset of strongly reducing groundwater). During sulfate reduction, dissolved sulfate is converted to 

hydrogen sulfide gas or to iron sulfide minerals that precipitate 

from groundwater and appear as finely disseminated black 

particulates that can accumulate in well bottoms and pressure 

tanks. Eighteen percent of the 116 water samples collected 

by the USGS during 1978–2009 (appendix table 4–1) were 

determined to have some sulfate reduction occurring. (Note 

that this percentage is a minimum value, because total sulfide—which is necessary to distinguish between sulfate- and 

iron-reducing redox environments—was not measured during 

the 1978 and 1980 sampling rounds and was not consistently 

measured in 1986). Although sulfate-reducing conditions were 

found in all four aquifers in the county, sulfide occurred at 

only low concentrations (less than 0.1 mg/L) in the Pottsville 

Formation. Concentrations greater than 0.1 mg/L were found 

at elevations below 1,060 ft in some, but not all, wells that 

tap the glacial deposits, Cuyahoga Group, or Berea Sandstone 

(fig. 31G).

Total sulfide concentrations were correlated to turbidity for the 16 domestic well samples collected in 2009 

(rho = 0.48, p-value = 0.0582). This could be because (1) precipitating iron sulfide minerals added turbidity (particulates) 

to groundwater or (2) hydrogen sulfide gas (a component 

of total sulfide) corroded the casings of wells, allowing soil 

or sediment to enter the wells and resulting in turbid water. 

However, independent indicators that soil and sediment have 

entered wells with elevated sulfide content, such as correlation 

of silica or organic carbon to turbidity, are not present.

Stratigraphic Traps That May Control Areas of 

Methane Accumulation

Methane in groundwater can be introduced from either 

microbial or thermogenic sources (Baldassare and Laughrey, 

1997). Microbial sources include methane generated under 

very reducing (methanogenic) redox conditions or from 
Considerations for Future Work 69

decomposition of landfill wastes. Thermogenic sources consist of organic matter deeply buried under sediments where 

elevated temperatures facilitate decomposition of the organic 

matter to petroleum and methane. Thermogenic gas can escape 

naturally from deep oil and gas reservoirs through fractures, or 

it can be released by humans during oil- and gas-drilling accidents, from pipelines, or from abandoned production wells. 

The Ohio Shale, which lies below the Berea Sandstone and 

the Bedford Shale, is a known natural gas source rock that has 

been evaluated by the U.S. Department of Energy (Hoover, 

1960; Janssens and de Witt, 1976; Schwietering, 1979) and 

could be a source of naturally occurring gas to water wells in 

Geauga County. However, no stable-isotope analyses were 

done as part of the current study that can be used to determine 

which of these sources of methane is reaching water wells in 

Geauga County.

Regardless of the source, free-phase (exsolved) gas will 

move from areas of higher pressure to areas of lower pressure. 

This can result in upward movement of gas through permeable rocks, joints, and fractures until it reaches a relatively 

impermeable layer of rock. In the Bainbridge Township area 

(fig. 11), gas released by drilling in 2007 initially migrated 

rapidly upwards until it reached the top of the Berea Sandstone, where it was temporarily trapped beneath the less 

permeable Cuyahoga Group. Once at the top of the Berea 

Sandstone, the buoyant gas migrated upslope, toward a high 

point at the top of the Berea Sandstone (a dome-shape structure north of the house that exploded). Over time, gas slowly 

worked its way upward through fractures in the Cuyahoga 

Group and concentrations in the Berea Sandstone diminished 

(Bair and others, 2010). 

It is possible that occurrences of methane in water wells 

elsewhere in the county could be related to the position of 

the wells relative to structural highs on the top of the Berea 

Sandstone. Figure 35 shows the elevation of the top of the 

Berea Sandstone in Geauga County based on data obtained 

from drilling logs. This map was created by ODNR in 1981 

using a limited number of data points. Where data points were 

more dense, a structural high was discerned that underlies 

GE-147, one of the USGS-sampled wells found to contain 

dissolved methane. Few data points exist near the location of 

the other two wells in which methane was detected by USGS 

personnel, or in Bainbridge Township where a structural high 

was mapped by ODNR–MRM personnel using additional data 

(Bair and others, 2010). If this hypothesis is correct, structural 

highs on the top of the Berea Sandstone could temporarily trap 

both gas that is naturally occurring (for instance, gas migrating upwards from the Ohio Shale) and gas released by drilling 

activities targeting deeper reservoirs. 

Pumping of groundwater also can create areas of low 

pressure within the aquifer. The two wells found to contain the 

higher concentrations of methane in the current study, wells 

GE-126 and GE-147, had experienced significant declines in 

water level from 1986 to 2009 (28.85 and 17.26 ft, respectively) (http://nwis.waterdata.usgs.gov/oh/nwis/gwlevels). 

These were the two largest changes in water level observed 

out of the 16 wells sampled. Lowering of water level reduces 

the pressure from overlying water in an area and can cause gas 

in an aquifer to preferentially migrate to these areas of low 

pressure.

Considerations for Future Work

During this study, some observations were made and 

factors were identified that are thought to affect water quality 

but that could be clarified by further geologic mapping in the 

county:

• The use of geographic information systems (GIS) 

software to analyze existing maps of groundwater 

levels (Jagucki and Lesney, 1995, plates 2–4) and 

land-surface elevations to produce a map of depth to 

groundwater along roads in the county could identify the areas where the sparing use of road-deicing 

chemicals would provide the improved protection of 

groundwater quality.

• Preliminary evidence suggests that shale units within 

and overlying the Pottsville Formation are associated 

with areas of elevated concentrations of iron, manganese, and arsenic in groundwater relative to areas in 

Pottsville Formation where the shale is not present. 

Mapping of these shale units may provide insight into 

(a) areas of the Pottsville Formation that are vulnerable 

to elevated concentrations of these constituents and 

(b) areas that likely receive lower recharge and may 

require more sparing water use.

• Mapping of structurally high areas on top of the Berea 

Sandstone may help identify areas in the county that 

are vulnerable to methane accumulation in water wells.
70 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009 Cuyahoga 

 River

Grand River

Chagrin River

GE-77

GE-108

GE-109

GE-126

GE-341

GE-332

GE-234

GE-202

GE-165 GE-151

GE-147

GE-141

GE-120

GE-103

GE-85A

GE-185A

Troy

Auburn

Burton Russell

Munson

Newbury

Chardon

Parkman

Chester Claridon

Montville

Thompson

Bainbridge

Hambden

Huntsburg

Middlefield

940

980

920

1000

1020

900

880

960

860

1040

1060

920

960

900

880

920

900

1060

1060

940

1040

81°10'

81°20'

41°40'

41°30'

Base from U.S. Geological Survey

1:24,000 digital data

Universal Transverse Mercator, zone 17

Berea Sandstone contours from Ohio Department of 

Natural Resources OF Map 132 (Gray, 1981).

Contour interval 20 feet, Datum NGVD 1929.

0 5 MILES

0 5 KILOMETERS

EXPLANATION

GE-108

Elevation of top of Berea Sandstone

Approximate location of Berea Sandstone 

outcrop or subcrop beneath glacial deposits 

—From Eberts and others, 1990, pl.1

Streams

Lakes

Water-quality site and well name for wells 

sampled by the U.S. Geological Survey in 

2009 (see table 3)

Wells in which methane was detected in 

June 2009

Cleveland

Figure 35.

Figure 35 Elevation of top of the Berea Sandstone in Geauga County, Ohio, and location of methane detections, 

June 2009.
Summary and Conclusions 71

Summary and Conclusions

Groundwater in Geauga County, Ohio, is an important 

resource because it is the main drinking-water supply for 

over 98 percent of residents in the county. For the past three 

decades, the U.S. Geological Survey (USGS) has worked 

together with Board of Commissioners and the Geauga 

County Planning Commission to evaluate the potential effects 

of human development and changing land use on the quantity and quality of the county’s groundwater resources. The 

purpose this most recent study was to (1) describe the status of 

groundwater quality in 2009 in the four primary aquifers used 

in the county—the glacial deposits, the Pottsville Formation, 

the Cuyahoga Group, and the Berea Sandstone, (2) describe 

the detection frequency of methane in water wells in the 

county in 2009, and (3) determine whether statistically significant changes in water quality had occurred since 1978. 

Increasing population brings with it a greater potential 

for harmful human effects on groundwater resources. Population in Geauga County increased by more than 72,000 people 

between 1950 and 2009, with almost half of the growth occurring in the 1950s and 1960s. Likely because of this rapid population growth and associated increased water use, ongoing 

water-level declines were noted in several long-term waterlevel network wells in the late 1970s and 1980s that stabilized 

by the mid-1990s. Declines occurred at wells in several townships and in wells tapping each of the four primary aquifers. 

Such water-level declines can potentially affect water quality 

by causing a well to withdraw water from different parts of an 

aquifer than were accessed previously. Other prevalent human 

activities in the county with the potential to adversely affect 

groundwater quality include (1) septic systems used by 70 

percent of homes to treat domestic sewage and wastewater, (2) 

spreading of septage (solids and liquids pumped from septic 

tanks) and biosolids (treated sludge from wastewater treatment 

plants) on agricultural fields in the eastern part of the county, 

(3) oil-field drilling that resulted in 1,112 producing oil and 

(or) gas wells as of 2008, and (4) the addition of 157 miles 

of township roads between 1981 and 2008 that led to greater 

amounts of road salt being purchased over time by the County 

Engineer for application to remove snow and ice. 

As of 2010, ten known areas of localized groundwater 

contamination in the county—most associated with commercial and industrial activities—had been documented by 

either the Ohio Environmental Protection Agency (Ohio EPA) 

Division of Drinking and Ground Water or Division of Environmental Response and Restoration or the Ohio Department 

of Natural Resources, Division of Mineral Resources Management (ODNR–MRM). Contaminants in these areas are typically chlorinated VOCs, gasoline compounds, and (or) road 

salt, and, in one case, methane. Remediation has occurred or 

is underway at most of these sites to remove harmful constituents from groundwater. 

To determine the status of groundwater quality in 

2009, the USGS collected samples from 16 domestic wells 

during June 9–19. All samples were analyzed for specific 

conductance, pH, turbidity, dissolved oxygen, major ions, 

alkalinity, total sulfide, nutrients, iron, manganese, arsenic, 

dissolved organic carbon, pesticides, total coliform, and 

Escherichia coli (E. coli) bacteria. Selected samples were also 

analyzed for fecal streptococci, fecal coliform bacteria, trace 

metals, and tritium. 

Forty-one of the 92 parameters analyzed had humanhealth benchmarks against which analytical results could be 

compared to evaluate suitability for drinking. Four of these 

benchmarks were exceeded at the following frequencies: 

arsenic (2 of 16 wells, 12.5 percent), total coliform bacteria 

(2 of 16 wells, 12.5 percent), fecal coliform bacteria (1 of 14 

wells, 7 percent), and sodium (6 of 16 wells, 38 percent). No 

domestic wells sampled in 2009 exceeded the health-based 

benchmark for manganese, although 5 of 65 wells (8 percent) 

sampled since 1978 have. Analyses from domestic wells were 

augmented with water-quality data from seven public-supply 

wells or well fields that were obtained from Ohio EPA. These 

public-supply data were typically collected between 2000 and 

2010. Similar to the domestic well data, these data indicated that some samples from public-supply wells have also 

exceeded health-based benchmarks for arsenic and sodium, 

along with occasional exceedances of health-based benchmarks for cadmium and lead. 

Concentrations of nitrate, pesticides, and VOCs were 

either low or not detected in groundwater samples from 

domestic and (or) public-supply wells. The maximum measured nitrate concentration of 1.73 milligrams per liter (mg/L) 

in water from 16 domestic wells sampled in 2009 was considerably less than the human-health benchmark of 10 mg/L. 

None of the pesticides with an established human-health 

benchmark that were included in analyses of groundwater 

samples from five of the seven public-supply well fields 

(2,4-D, alachlor, atrazine, carbofuran, diquat, endothall, 

glyphosate, metolachlor, metribuzin, oxamyl, picloram, or 

simazine) were detected between 2000 and 2010. Similarly, of 

the 52 pesticides included in the USGS analyses of water from 

domestic wells, only the herbicide atrazine was detected at a 

concentration above the laboratory reporting level. Atrazine 

was detected in one well at a concentration of 0.0073 microgram per liter (μg/L), which is below the health-based drinking water standard of 3 μg/L. This well had the largest area 

of upgradient agricultural land use of any well sampled. Also, 

depth to groundwater at this well was very shallow (less than 

10 feet [ft] below land surface), adding to its vulnerability.

Although no samples from domestic wells were analyzed 

for VOCs during the current study, water from the seven 

public-supply wells—both untreated and treated samples—

were analyzed for almost 100 VOCs between 1995 and 

2009. With one exception, only chlorination byproducts were 

detected in water produced by these wells, but they were at 

concentrations below health-based benchmarks. Chlorination 

byproducts do not occur naturally in groundwater but form 

when chlorine added to disinfect water combines with organic 

matter inherently present in the groundwater. The one VOC 

detected in any of the studied public-supply wells that was not 
72 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

a chlorination byproduct was total xylenes (a solvent that is a 

component of gasoline). Total xylenes were detected in 2 of 

34 samples from a public-supply well field in a developed and 

densely populated area of Bainbridge Township. Concentrations did not exceed the human-health benchmark (10 mg/L) 

for this constituent. 

Water-quality data collected in 2009 were also compared 

to Secondary Maximum Contaminant Levels (SMCLs) developed by the U.S. Environmental Protection Agency for constituent concentrations that affect drinking-water aesthetics. 

Iron and manganese were the constituents that most frequently 

exceeded SMCLs in groundwater of Geauga County (in 

samples from 10 of 16 domestic wells and in untreated water 

from 3 of 4 public-supply wells). Concentrations of iron and 

manganese above the SMCL may cause staining of fixtures 

and laundry. Although no SMCL is established for total sulfide 

(which includes hydrogen sulfide gas with its characteristic 

rotten-egg odor and iron sulfide minerals that appear as finely 

disseminated particulates in water), this undesirable constituent was detected in half of the 16 domestic wells sampled.

To evaluate the frequency of water wells that produce 

natural gas in the county, the USGS (1) screened 16 wells 

across the county for combustible gas fraction at the wellhead and in the headspace of water samples and (2) analyzed 

samples for dissolved gases in which combustible gas was 

detected or in which exsolving gases were observed during 

sampling. Combustible gas was not detected immediately 

below the well cap at any of the 16 wellheads screened by 

USGS personnel. Yet when water was pumped from each well 

and the air above the water (headspace) in a closed container 

was analyzed, water from three of the wells (19 percent) was 

found to contain detectable combustible gas (0.10 to 0.40 

percent by volume). All three detections were in wells tapping the Cuyahoga Group or the Berea Sandstone, and these 

detections were all less than the lower explosive limit of 5 

percent by volume—the concentration at which methane in 

air can be flammable if an ignition source is present. Analyses of dissolved gas composition in water from these three 

wells showed methane concentrations ranging from 0.0065 to 

1.88 mg/L. 

To evaluate whether concentrations of frequently detected 

constituents consistently increased or decreased over time, 

the strength of the association between sampling year (time) 

and constituent concentration was statistically evaluated for 

116 water-quality samples collected by the USGS in 1978, 

1980, 1986, 1999, and 2009 from a total of 65 wells (generally 

domestic wells or ones serving small businesses or churches) 

across the county. Results indicate that many of the constituents that were analyzed for decades exhibited no consistent 

temporal trends at a statistically significant level (p-value 

less than 0.05); fluctuations in concentrations of these constituents represent natural variation in groundwater quality. 

Dissolved oxygen, calcium, and sulfate concentrations and 

chloride:bromide ratios increased over time in one or more 

aquifer, while pH and concentrations of bromide and dissolved 

organic carbon decreased over time. None of these constituents have a health-based benchmark against which to assess 

water-quality changes, but aesthetically based standards have 

been established for sulfate and pH. Whereas sulfate concentrations are still well below the SMCL, a continued downward 

trend in pH in future years, if it occurs, could cause a greater 

number of samples fall below the recommended pH range of 

6.5–8.5. Detections of total coliform bacteria and nitrate did 

not become more frequent from 1986 to 2009, even though 

potential sources of these constituents, such as number of 

septic systems (linked to population) and percent developed 

land in the county, increased during this period. The evaluation 

of temporal trends by aquifer found that constituent concentrations in samples from the Berea Sandstone were largely 

unchanged over time, which is consistent with tritium agetracer data and simulations of groundwater flow from previous 

studies indicating that water in the Berea Sandstone generally 

entered the groundwater system prior to 1953, before most of 

the county’s population growth and development occurred. 

In contrast, samples from Cuyahoga Group had the greatest 

number of constituents with concentrations exhibiting temporal trends. 

The primary effect of human activities on groundwater 

quality found during this study is the input of salinity (chloride) at land surface. The main sources of chloride near land 

surface are road salt and septic leachate rather than surface 

spills of brine produced during oil-field drilling or spraying of 

roads with oil-field brine for dust control, based on ratios of 

chloride to bromide. The correlation of chloride concentration 

to distance of well from road for 31 wells sampled in 1999 

suggests that road salt is the dominant source of chloride. 

Inputs of sulfate at land surface were also identified on 

the basis of decreases in concentrations of sulfate with depth 

that did not appear to be a function of the redox condition of 

groundwater. A likely source of sulfate is the combustion of 

fossil fuels, which produces sulfate ions and acidity in rainfall 

of northeastern Ohio.

Only one well sampled in 2009 (GE-141) was within 500 

meters downgradient of a field authorized for biosolids spreading (9.9 acres permitted to the McFarland Creek Wastewater 

Treatment Plant). This was also the only well where total coliform concentrations increased from 1999 to 2009, and where 

total coliforms co-occurred with a fecal coliform detection, 

a finding that strengthens the likelihood that water from this 

well has been affected by human or animal waste. However, 

further investigation determined that, if land application of 

biosolids from the wastewater treatment plant ever happened, 

it occurred prior to 2006. Documented die-off rates of fecal 

coliform bacteria are on the order of weeks, not years, so it is 

much more likely that this well is influenced by leachate from 

on-lot septic systems used in this area than by past spreading 

of biosolids. 
Summary and Conclusions 73

Most of the constituents exceeding human-health benchmarks and aesthetic standards are ones that are naturally present in aquifer sediments and rocks in Geauga County. Concentrations of these constituents in groundwater are controlled by 

the following natural geochemical processes in the subsurface:

• Evolution of groundwater along a flow path—As 

water moves from higher to lower elevations along 

a groundwater flow path, it dissolves minerals from 

aquifer rocks and sediments, causing concentrations 

of pH, alkalinity, potassium, sodium, silica, fluoride, 

boron, specific conductance, and total dissolved solids 

to increase in groundwater at lower elevations.

• Cation exchange—In the Cuyahoga Group and 

the underlying Berea Sandstone, sodium ions that 

adsorbed to clays at the time of aquifer deposition 

migrate into groundwater as they are replaced by other 

cations moving from groundwater to adsorption sites 

on clays. The result is enriched sodium concentrations in groundwater produced by wells tapping the 

Cuyahoga Group and the Berea Sandstone (median 

concentration of 56.9 mg/L for the period 1978–2009) 

compared to water from wells tapping the glacial 

deposits and Pottsville Formation (median concentration of 7.74 mg/L).

• Oxidation-reduction (redox) geochemical reactions—These microbially induced reactions control 

concentrations of dissolved oxygen, nitrate, ammonia, 

manganese, iron, arsenic, sulfate, and sulfide. On the 

basis of measured concentrations of 5 constituents in 

116 groundwater samples collected during 1978–2009, 

the dominant redox reaction occurring in the part of 

the aquifer from which the samples were withdrawn 

was categorized. Results indicate that most groundwater samples (60 percent) were strongly reducing. 

Elevated concentrations of arsenic, iron, manganese, 

and sulfide (present either as hydrogen sulfide gas or 

as precipitating iron sulfide minerals) are associated 

with this type of redox environment, which occurred 

in all four aquifers. Eighteen percent of samples—only 

ones from the Pottsville Formation or the Berea Sandstone—were oxic. Nitrate (maximum concentration of 

6.0 mg/L) was detected in this type of environment. No 

samples were categorized as methanogenic (methane 

producing).

Because some samples from the Pottsville Formation 

and the Berea Sandstone are strongly reducing and others are 

oxic, attempts were made to further document spatially where 

these two redox conditions occur so that contaminant occurrence can be better anticipated by planners and well owners. 

Wells tapping strongly reducing groundwater in the Pottsville 

Formation tended to have a greater thickness of overlying 

low-permeability material such as clay and shale than wells 

tapping oxic or nitrate-reducing groundwater in the same aquifer. Spatial analysis of water-quality data indicate that strongly 

reducing conditions may be more prevalent in the Pottsville 

Formation in the southeastern corner of the county, and oxic 

and nitrate-reducing conditions may be more prevalent in 

the westernmost townships. In the Berea Sandstone, oxic or 

suboxic water is more prevalent in locations very near areas 

where the Berea Sandstone crops out (where it is exposed 

and visible at land surface) or is covered by glacial sediments 

filling an ancestral stream valley. Strongly reducing wells are 

located farther from these outcrops. Examination of relation 

of redox conditions to well characteristics indicates that oxic 

conditions in the Berea Sandstone were found at well locations 

where either depth to groundwater was shallow (less than 45 

ft below land surface) or the measured water level was within 

the open interval (uncased portion) of the well. Wells tapping 

strongly reducing groundwater had depths to water greater 

than 60 ft and measured water levels of 15 ft or more above 

the open interval of the well. 

In summary, factors associated with the occurrence of 

both naturally occurring and human-induced contaminants 

are listed in the table on the next page. Because most 

homeowners know if their well water has a high iron content, 

iron concentration is used in this table as a signal that other 

contaminants may be present in the water. The aquifer tapped 

by a well can be discerned by comparing the well location, 

land-surface elevation, and information on the driller’s well 

log to elevations of the different aquifers in the county as 

shown in figure 31.
74 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Source Constituent Factors associated with contaminant occurrence Naturally occurring

Arsenic at concentrations 

exceeding the humanhealth benchmark 

(10 μg/L)

Wells producing strongly reducing water (signaled by iron concentrations greater than 

100 μg/L—especially if the concentration is high enough to affect taste and stain 

fixtures or laundry). At particular risk are wells having more than about 30 ft of clay 

above the uncased portion of the well, or wells tapping the Pottsville Formation in areas where sandstone is overlain by shale. Berea Sandstone wells with depth to water 

of more than 60 ft may also be at risk.

Manganese at concentrations 

exceeding the humanhealth benchmark 

(300 μg/L)

Wells tapping the Pottsville Formation in Burton, Middlefield, and Parkman Townships 

(where manganese content of aquifer materials and [or] overlying sediments appears 

to be higher than elsewhere in the county) and that produce strongly reducing water. 

(Strongly reducing water is signaled by iron concentrations greater than 100 μg/L—

especially if the concentration is high enough to affect taste and stain fixtures or 

laundry). Wells producing water with a pH less than 7 may be particularly at risk.

Sodium at concentrations exceeding the human-health 

benchmark (20 mg/L)

Wells tapping the Berea Sandstone or Cuyahoga Group.

Total sulfide 

(Hydrogen sulfide gas 

and [or] precipitating iron 

sulfide minerals)

Wells producing strongly reducing water (signaled by iron concentrations greater than 

100 μg/L—especially if the concentration is high enough to affect taste and stain fixtures or laundry). Sulfide concentrations increase at lower elevations, with concentrations greater than 0.1 mg/L occurring in some wells that have a well bottom elevation 

below 1,060 ft and tap the glacial deposits, Cuyahoga Group, or Berea Sandstone. 

Uncertain

Methane Wells tapping the Berea Sandstone or Cuyahoga Group. Signs of methane include 

spurting faucets, cloudy water, and bubbles in water. Limited evidence suggests that 

a well that has experienced a significant decrease in water level since it was drilled 

and (or) a well that intersects a structurally high area at the top of the Berea Sandstone (shown as an area of closed contours and high elevation in figure 35) may be 

more likely to contain methane than a well that does not have these characteristics.

Human activities

Total coliform bacteria

at concentrations exceeding the human-health 

benchmark of 4 colonies 

per 100 milliliters of water

Wells with a total depth of less than 140 ft below land surface. Wells with a total depth 

of less than 70 ft below land surface and (or) with a shallow cased interval are particularly at risk. Also at risk are wells that produce water with visible turbidity. 

Chloride

(although concentrations 

exceeding the SMCL of 

250 mg/L are unlikely)

Wells with shallow depth to groundwater (less than 50 ft below land surface, with 

greater risk at depths of less than 30 ft below land surface), particularly if the well is 

near a road and (or) in an area with upgradient agricultural and developed land cover. 

Nitrate

(although concentrations 

exceeding the humanhealth benchmark of 10 

mg/L are unlikely)

The main criterion for the presence of nitrate is that the well taps oxic or nitrate-reducing water in the Pottsville Formation or Berea Sandstone (characterized by low iron 

concentrations [less than 100 μg/L]). Nitrate concentrations greater than 1 mg/L occur almost exclusively in water from wells with bottom elevations higher than 1,075 

ft that tap the Pottsville Formation. (These wells also have casing that extends less 

than 75 ft below land surface.) Limited evidence suggests that wells with upgradient 

agricultural or developed land are likely to contain somewhat higher concentrations 

of nitrate than wells with upgradient forested land. 
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Appendixes

Appendix 1. Variation in Water Levels in Selected Long-Term Network Wells Relative to 

Variation in Annual Precipitation

Appendix 2. Quality Assurance/Quality Control

Appendix 3. Land Cover and Population Upgradient of Each Well

Appendix 4. Water-Quality Data

Appendix 5. Oxidation-Reduction Classification of Samples
82 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Appendix 1. Variation in Water Levels 

in Selected Long-Term Network 

Wells Relative to Variation in Annual 

Precipitation

To determine the amount of groundwater-level fluctuation 

in each network well that is caused by variation in annual 

precipitation, we used a visual curve-matching procedure 

whereby the y-scale of the hydrograph for each well was 

adjusted so that annual fluctuations in water level from1996 

through 2012 (plotted on the primary y-axis) coincided, as 

closely as possible, with annual fluctuations in precipitation, 

plotted on a secondary y-axis (fig. 1–1, at end of appendix). 

Annual precipitation data are from Ohio Department of 

Natural Resources (1977–2012). Yearly departure from 

normal1 is taken from the December issue, departure from 

normal for the past 12 months in Northeast Ohio. Thus, when 

graphed, the departure from normal for a given year is plotted 

on December 31 of that year.

1

 “Normal” precipitation from 1995 through 2001 is based on average 

annual precipitation for the years 1941–1990. “Normal” precipitation for 

2002 through 2011 is based on average annual precipitation for 1951–2000. 

“Normal” precipitation for 2012 is based on average annual precipitation for 

1961–2010.

Since 1994, water-level fluctuations in most network 

wells have generally mimicked variations in annual 

precipitation (although there may be a lag time between 

precipitation and aquifer response). This similarity indicates 

that inflow to and outflow from the groundwater system are in 

equilibrium at these well locations. In Geauga County, inflow 

consists almost exclusively of infiltrating precipitation (Eberts 

and others, 1990), whereas outflow consists of discharge to 

springs, streams, lakes, wetlands, pumping wells, and water 

loss due to evaporation and transpiration by plants. Because 

the curve-matching procedure is unique to each well, it 

incorporates differences in the water-level response to annual 

precipitation that is influenced by depth to groundwater, the 

aquifer tapped by the well, and permeability of rocks and 

sediments overlying the aquifer in the vicinity of the well. 

Once the curve-matching procedure has been done for a well 

by using data covering a period of a few years, both future 

groundwater levels and past groundwater levels in that well 

can be expected to plot near the annual precipitation trendline, 

as long as the hydrograph scales remain the same and as long 

as in the inflow and outflow equilibrium conditions that were 

used for curve-matching remain essentially unchanged.

The curve-matched plots (1996–2012) were used to 

evaluate historical, intermittent water levels for the 13 

wells for which data are available from previous studies 

(periods of record ranging from 1978, 1980, or 1985 to 1994) 

Table 1-1. Comparison of water-level difference, 1986–1994, to approximate magnitude of water-level departure 

from annual precipitation trendline for wells with historical data (1978–1994) in Geauga County, Ohio.

Year began 

measuring 

water levels 

at this well

Well 

name Aquifer

Water-level 

difference, in feet, 

1986–1994 

(from Jagucki and 

Lesney, 1995)

Pre-1994 water 

level departs 

from annual 

precipitation 

trendline?1

Approximate 

magnitude of 

departure,2

in feet

1978 GE-22 Pottsville Formation (

3

) No 0.0

GE-23 Pottsville Formation –6.64 Yes –6.0

GE-76 Glacial deposits 0.58 Yes –2.5

1980 GE-103 Berea Sandstone –8.29 Yes –12.0

GE-106 Cuyahoga Group –0.63 Yes –5.0

GE-112 Pottsville Formation –1.50 Yes –4.0

GE-119 Pottsville Formation –3.18 Yes –6.0

1985 GE-136 Cuyahoga Group –4.73 Yes –2.0

GE-139 Pottsville Formation –0.79 No 0.0

1986 GE-150 Pottsville Formation –0.47 Yes –2.0

GE-163 Pottsville Formation –7.19 Yes –6.5

GE-170 Cuyahoga Group –0.29 No 0.0

GE-202 Pottsville Formation –2.70 Yes –2.0

1

 Based on fig. 1–1A and B.

2

 Calculated as difference between earliest water-level measurement at a given well and its expected plotting locaton on that date 

along the annual precipitation trendline (see fig. 1–1A, red arrow labeled as “water-level decline”).

3

No water-level measurements were made at this well in 1986.
Appendix 1 83

(fig. 1–1A and B). In 10 of the 13 wells, intermittent water 

levels prior to 1994 plotted above the current equilibrium 

levels denoted by the precipitation trendline (fig. 1–1A), 

indicating that groundwater system inflows were greater in the 

past than they have been since 1994 and (or) outflow volumes 

were smaller in the past than they have been since 1994. 

Because it is clear that annual precipitation (inflow) prior to 

1994 was not greater than precipitation after 1994 (fig. 1–1A), 

the water-level declines that occurred prior to 1994 must have 

been caused by an increase in groundwater outflow. Possible 

reasons for increased outflow will be discussed in subsequent 

paragraphs. The magnitude of the water-level decline in each 

of the 10 wells was approximated as distance, in feet, between 

the earliest water-level measurement at a well and its expected 

plotting location on that date along the annual precipitation 

trendline (denoted by a red arrow in fig. 1–1A). Water-level 

declines (departures from annual precipitation trendline) 

ranged from approximately 2 to 12 feet (ft) (table 1–1), and 

were noted in wells tapping each of the four primary aquifers.

Water-level declines in the county were likely much more 

widespread than indicated by just the 10 wells documented 

in figure 1–1A. Table 1–1 and figure 1–2 show the relation of 

differences in measured water levels between 1986 and 1994 

as reported by Jagucki and Lesney (1995) to magnitude of 

water-level departures from the annual precipitation trendline 

for the 10 wells in the long-term network with documented 

declines (denoted by red arrows in fig. 1–1A). These data 

suggest that measured water-level differences of 1 ft or 

more between 1986 and 1994 correspond to historic water 

levels that departed from the annual precipitation trendline 

or, in other words, showed a water-level decline that was 

greater than would be expected due to fluctuations in annual 

precipitation. Thus, of the 88 wells measured by Jagucki 

and Lesney (1995) in both 1986 and 1994, the 50 wells 

(57 percent) with water levels that declined by 1 ft or more 

likely were influenced by factors other than differences in 

annual precipitation between the two years. (At the time that 

Jagucki and Lesney reported their findings [1995], there were 

insufficient data to distinguish a water-level decline caused 

by a year of low precipitation from a water-level decline 

caused by increased water withdrawals.) Jagucki and Lesney 

(1995) noted that water-level declines between 1986 and 1994 

occurred in all four aquifers and that water-level declines of 

greater than 10 ft were measured primarily in wells tapping the 

Cuyahoga Group and Berea Sandstone.

The cause for the water-level decline in many wells 

during the late 1970s and 1980s is not clear. The most likely 

explanation is that water levels in these wells reflected an 

ongoing response to the rapid population growth (and the 

associated increased groundwater withdrawals) that occurred 

from 1950 to 1970 (fig. 4). In this scenario, water-level 

declines would have begun before water levels were first 

measured in 1978. Slowing population growth in the 1980s 

might have allowed water levels in most wells to stabilize 

by the 1990s and to reach a new equilibrium between inflow 

and outflow. A second contributing factor to the observed 

water-level declines could be the magnitude 5.0 earthquake on 

January 31, 1986 (epicenter just north of Hambden Township) 

(fig. 7). This earthquake might have created new bedrock 

fractures that increased aquifer drainage and discharge, as 

occurred in nearby Pymatuning, Pennsylvania following a 

magnitude 5.2 earthquake in 1998 (Fleeger and others, 1999). 

Evidence for this hypothesis is the fact that the greatest 

decline was observed in the well closest to the epicenter (well 

GE-103) and that steep declines occurred in other wells 

(GE-106, GE-163, GE-202) in the months after the earthquake 

in 1986 (fig. 1–1A) but before the decrease in precipitation that 

occurred in 1987 and 1988.

-14.0

-12.0

-10.0

-8.0

-6.0

-4.0

-2.0

0

-9.00 -8.00 -7.00 -6.00 -5.00 -4.00 -3.00 -2.00 -1.00 0 1.00 2.00

Difference between 1986 and 1994 water level, in feet

Linear regression

Departure of earliest water-level measurement 

from annual precipitation trendline, in feet

Ambiguous area—water-level differences of less 

than1 ft may or may not correspond to a departure 

from the annual precipitation trendline.

Figure 1–2. Relation of 

measured difference in water 

level between 1986 and 1994 

to departure of water level 

from annual precipitation 

trendline, 1986 or earlier. 

(Difference between 1986 and 

1994 water level is from Jagucki 

and Lesney [1995, table 5]; 

departure of earliest waterlevel measurement from annual 

precipitation trendline is denoted 

by red arrow, fig 1–1A.)
84 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

-10

-5

0

5

10

15

20

20 25

21

22

23

24

25

26

1975 1980 1985 1990 1995 2000 2005 2010 2015

Depth to water, in feet below land surface

Year

GE-76 (glacial deposits)

January 31, 1986, earthquake

Annual precipitation

Water-level decline = 2.5 ft

Precipitation departure from normal, in inches

-10

-5

0

5

10

15

20

9 25

A. Wells with water level that departs from precipitation trend line prior to 1994

11

13

15

17

19

21

23

1975 1980 1985 1990 1995 2000 2005 2010 2015

Precipitation departure from normal, in inches

Depth to water, in feet below land surface

Year

Water-level decline = 6 ft

GE-23 (Pottsville Fm.)

January 31, 1986, earthquake

Annual precipitation

Figure 1–1. Relation of water levels in selected long-term network wells, 1978–2012, to variation in annual precipitation. 

(ft, feet; Fm., formation. Annual precipitation data are departure from normal for the climatological Northeast Region of 

Ohio [Ohio Department of Natural Resources, 1977–2012]. “Normal precipitation” and plotting conventions are described 

in appendix 1 text.)
Appendix 1 85

-20

-15

-10

-5

0

5

10

15

20

25

30

35

30 40

31

32

33

34

35

36

37

38

39

40

1975 1980 1985 1990 1995 2000 2005 2010 2015

Precipitation departure from normal, in inches

Depth to water, in feet below land surface

Year

Water-level decline = 5 ft

GE-23 106 (Cuyahoga Group)

January 31, 1986, earthquake

Annual precipitation

A. Wells with water level that departs from precipitation trend line prior to 1994—Continued

-30

-20

-10

0

10

20

30

40

50

60

70

78

80

82

84

86

88

90

92

94

96

98

1975 1980 1985 1990 1995 2000 2005 2010 2015

Precipitation departure from normal, in inches

Depth to water, in feet below land surface

Year

Water-level decline = 12 ft

GE-103 (Berea Sandstone)

January 31, 1986, earthquake

Annual precipitation

Figure 1–1. Relation of water levels in selected long-term network wells, 1978–2012, to variation in annual 

precipitation. (ft, feet; Fm., formation. Annual precipitation data are departure from normal for the climatological 

Northeast Region of Ohio [Ohio Department of Natural Resources, 1977–2012]. “Normal precipitation” and 

plotting conventions are described in appendix 1 text.)—Continued
86 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

-25

-15

-5

5

15

25

35

6 45

8

10

12

14

16

18

20

1975 1980 1985 1990 1995 2000 2005 2010 2015

Precipitation departure from normal, in inches

Depth to water, in feet below land surface

Year

Water-level decline = 6 ft

GE-119 (Pottsville Fm.)

January 31, 1986, earthquake

Annual precipitation

-20

-10

0

10

20

30

40

42

44

46

48

50

52

54

1975 1980 1985 1990 1995 2000 2005 2010 2015

Precipitation departure from normal, in inches

Depth to water, in feet below land surface

Year

Water-level decline = 4 ft

A. Wells with water level that departs from precipitation trend line prior to 1994—Continued

GE-112 (Pottsville Fm.)

January 31, 1986, earthquake

Annual precipitation

Figure 1–1. Relation of water levels in selected long-term network wells, 1978–2012, to variation in annual 

precipitation. (ft, feet; Fm., formation. Annual precipitation data are departure from normal for the climatological 

Northeast Region of Ohio [Ohio Department of Natural Resources, 1977–2012]. “Normal precipitation” and plotting 

conventions are described in appendix 1 text.)—Continued
Appendix 1 87

-10

-5

0

5

10

15

20

20 25

22

24

26

28

30

32

34

1975 1980 1985 1990 1995 2000 2005 2010 2015

Precipitation departure from normal, in inches

Depth to water, in feet below land surface

Year

Water-level decline = 2 ft

GE-150 (Pottsville Fm.)

January 31, 1986, earthquake

Annual precipitation

A. Wells with water level that departs from precipitation trend line prior to 1994—Continued

-20

-10

0

10

20

30

10

12

14

16

18

20

22

24

26

28

1975 1980 1985 1990 1995 2000 2005 2010 2015

Precipitation departure from normal, in inches

Year

Depth to water, in feet below land surface

Water-level decline = 2 ft

GE-136 (Cuyahoga Group)

January 31, 1986, earthquake

Annual precipitation

Figure 1–1. Relation of water levels in selected long-term network wells, 1978–2012, to variation in annual precipitation. 

(ft, feet; Fm., formation. Annual precipitation data are departure from normal for the climatological Northeast Region of 

Ohio [Ohio Department of Natural Resources, 1977–2012]. “Normal precipitation” and plotting conventions are described in 

appendix 1 text.)—Continued
88 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

-15

-10

-5

0

5

10

15

20

25

27.0 30

27.5

28.0

28.5

29.0

29.5

30.0

30.5

31.0

31.5

32.0

1975 1980 1985 1990 1995 2000 2005 2010 2015

Precipitation departure from normal, in inches

Depth to water, in feet below land surface

Year

Water-level decline = 2 ft

GE-202 (Pottsville Fm.)

January 31, 1986, earthquake

Annual precipitation

-20

-10

0

10

20

30

40

6 50

8

10

12

14

16

18

20

1975 1980 1985 1990 1995 2000 2005 2010 2015

Precipitation departure from normal, in inches

Depth to water, in feet below land surface

Year

Water-level decline = 6.5 ft

A. Wells with water level that departs from precipitation trend line prior to 1994—Continued

GE-163 (Pottsville Fm.)

January 31, 1986, earthquake

Annual precipitation

Figure 1–1. Relation of water levels in selected long-term network wells, 1978–2012, to variation in annual 

precipitation. (ft, feet; Fm., formation. Annual precipitation data are departure from normal for the climatological 

Northeast Region of Ohio [Ohio Department of Natural Resources, 1977–2012]. “Normal precipitation” and plotting 

conventions are described in appendix 1 text.)—Continued
Appendix 1 89

-15

-10

-5

0

5

10

15

20

30 25

32

34

36

38

40

42

1975 1980 1985 1990 1995 2000 2005 2010 2015

Precipitation departure from normal, in inches

Depth to water, in feet below land surface

Year

GE-139 (Pottsville Fm.)

January 31, 1986, earthquake

Annual precipitation

B. Wells showing no departure from precipitation trend line prior to 1994

-10

-5

0

5

10

15

20

10.0 25

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

14.5

15.0

1975 1980 1985 1990 1995 2000 2005 2010 2015

Precipitation departure from normal, in inches

Depth to water, in feet below land surface

Year

GE-22 (Pottsville Fm.)

January 31, 1986, earthquake

Annual precipitation

Figure 1–1. Relation of water levels in selected long-term network wells, 1978–2012, to variation in annual 

precipitation. (ft, feet; Fm., formation. Annual precipitation data are departure from normal for the climatological 

Northeast Region of Ohio [Ohio Department of Natural Resources, 1977–2012]. “Normal precipitation” and plotting 

conventions are described in appendix 1 text.)—Continued
90 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

-25

-15

-5

5

15

25

35

6 45

8

10

12

14

16

18

20

1975 1980 1985 1990 1995 2000 2005 2010 2015

Precipitation departure from normal, in inches

Depth to water, in feet below land surface

Year

GE-119 (Pottsville Fm.)

Annual precipitation

C. Wells showing departure from precipitation trend line some time after 1994

B. Wells showing no departure from precipitation trend line prior to 1994—Continued

-10

-5

0

5

10

15

20

39 25

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

1975 1980 1985 1990 1995 2000 2005 2010 2015

Precipitation departure from normal, in inches

Depth to water, in feet below land surface

Year

GE-170 (glacial deposits)

January 31, 1986, earthquake

Annual precipitation

Figure 1–1. Relation of water levels in selected long-term network wells, 1978–2012, to variation in annual 

precipitation. (ft, feet; Fm., formation. Annual precipitation data are departure from normal for the climatological 

Northeast Region of Ohio [Ohio Department of Natural Resources, 1977–2012]. “Normal precipitation” and plotting 

conventions are described in appendix 1 text.)—Continued
Appendix 1 91

-20

-15

-10

-5

0

5

10

15

20

25

23.5 30

24.0

24.5

25.0

25.5

26.0

26.5

27.0

27.5

1975 1980 1985 1990 1995 2000 2005 2010 2015

Departure from normal precipitation, in inches

Depth to water, in feet below land surface

Year

GE-349 (Pottsville Fm.)

 Annual precipitation

Approximate start of water-level 

decline (January 2007)

Period of record for this well is 1996 to present

-20

-10

0

10

20

30

10

12

14

16

18

20

22

24

26

28

1975 1980 1985 1990 1995 2000 2005 2010 2015

Precipitation departure from normal, in inches

Year

Depth to water, in feet below land surface

GE-136 (Cuyahoga Group)

Annual precipitation

Approximate start of water-level 

decline (2007)

C. Wells showing departure from precipitation trend line some time after 1994—Continued

Figure 1–1. Relation of water levels in selected long-term network wells, 1978–2012, to variation in annual 

precipitation. (ft, feet; Fm., formation. Annual precipitation data are departure from normal for the climatological 

Northeast Region of Ohio [Ohio Department of Natural Resources, 1977–2012]. “Normal precipitation” and plotting 

conventions are described in appendix 1 text.)—Continued
92 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

-25

-20

-15

-10

-5

0

5

10

15

20

25

60 30

65

70

75

80

85

1975 1980 1985 1990 1995 2000 2005 2010 2015

Precipitation departure from normal, in inches

Depth to water, in feet below land surface

Year

GE-352 (glacial deposits)

Approximate start of water-level 

decline (April 2010)

Period of record for this well is 1996 to present

Annual precipitation

C. Wells showing departure from precipitation trend line some time after 1994—Continued

Figure 1–1. Relation of water levels in selected long-term network wells, 1978–2012, to variation in annual 

precipitation. (ft, feet; Fm., formation. Annual precipitation data are departure from normal for the climatological 

Northeast Region of Ohio [Ohio Department of Natural Resources, 1977–2012]. “Normal precipitation” and plotting 

conventions are described in appendix 1 text.)—Continued
Appendix 2 93

Appendix 2. Quality Assurance/Quality 

Control

To ensure sample integrity and final quality of data, 

quality-control (QC) samples—including sequential replicate 

samples, field blanks, and source solution blanks—were 

collected in 1999 and 2009 at a rate of 10 percent for most 

analytes (table 2–1). QC samples collected in 1999 are 

described by Jagucki and Darner (2001, appendix A). QC 

samples collected in 2009 are described below. QC data 

from years prior to 1999 were not available. To ensure that 

procedures were correctly and consistently followed, written 

protocols were distributed to field personnel, data entries were 

checked by a second person, and field personnel adhered to 

maximum sample holding times.

Assessing sampling and laboratory variability (within 

a sampling round).—Sequential replicates were collected in 

1999 and 2009 for most constituents to assess sampling and 

analytical variability (Francy and Shaffer, 2008). Sequential 

replicates were collected from the same well immediately 

after the environmental sample by use of the same equipment 

and field methods, and they were analyzed for the same 

constituents as the environmental samples. (The exceptions 

were trace metals and tritium, for which no replicate 

samples were analyzed.) In 2009, replicate samples for 

alkalinity, major ions, iron, manganese, arsenic, sulfide, and 

organic carbon were collected at wells GE-165 and GE-341 

(table 2–1). An additional replicate for alkalinity was collected 

at well GE-332. Replicate samples for pesticides and nutrients 

were collected from wells GE-332 and GE-341 because 

measurable concentrations of nitrate had been found in water 

from these wells during previous sampling rounds. Bacteria 

quality-assurance/quality-control (QA/QC) requirements 

were more stringent than requirements for other analytes. At 

all sites in 2009, duplicate platings were done from the same 

sample bottle but were counted by different analysts, and 

results were averaged. Additional platings were done from a 

second, replicate sample collected at well GE-341 (table 2–1) 

in 2009. Replicate samples for dissolved methane gas were 

collected at all three sites where the headspace screen detected 

combustible gas—GE-77, GE-126, and GE-147. 

Results of replicate analyses are listed in table 2–1, 

with the exception of results for replicate analyses of 52 

pesticides that were not detected in any environmental or 

quality-control sample. Out of a total of 164 comparisons of 

replicate constituent analyses in 2009, 155 (94 percent) had a 

relative percent difference that was less than 5 percent. Only 

nine comparisons in 2009 and five in 1999 had relative percent 

differences that were greater than 5 percent; these are shown 

in bold type in table 2–1 and generally occurred at very low 

concentrations. When concentrations are low, a small amount 

of change in concentration in the replicate sample represents 

a large percent difference. Even for the nine problem values 

in 2009, the differences in concentration were not enough 

to change the determination of whether or not a constituent 

exceeded health-based or aesthetically based water-quality 

standards or changed the hazard level indicated by the 

measured methane concentrations. 

Assessing sample contamination.—To identify bias 

caused by contamination from equipment, supplies, and 

ambient environmental conditions, one field blank was 

collected (Francy and Schaffer, 2008) in 2009 at a sampling 

location after the equipment had been cleaned. Cleaning, 

or decontamination, procedures are described in the 

Methods section of this report. The field blank for unfiltered 

constituents was collected by gravity-feeding deionized 

water through the sample tubing. For filtered constituents, 

a peristaltic pump was used to provide enough pressure to 

push the water through the filter. A portion of the water was 

collected and preserved for chemical analysis of major ions, 

iron, manganese, arsenic, and nutrients. The field blank for 

pesticides and dissolved organic carbon (DOC) used organicfree water rather than deionized water. For the DOC blank, the 

first 200 milliliters (mL) of organic-free water was gravity-fed 

through the silicon sample tubing and then discarded. The 

subsequent water was forced through the DOC stainless steel 

filter cartridge by use of nitrogen gas. 

One bottle of organic-free water was used in the process 

of preparing the pesticide and DOC field blank. When the 

bottle was opened, some of the unfiltered water was poured 

immediately into two sample containers and was sent to 

the NWQL for DOC and pesticide analysis to verify that 

the source water used to prepare the equipment blanks was 

organic free. This sample is referred to as the source-solution 

blank (Francy and Shaffer, 2008) (table 2–1).

It is expected that the blank sample collected in 2009 

would have a measurable pH (because even deionized water 

has a pH). However, concentrations of all other constituents 

in the blank were below the laboratory reporting level, 

except for the pesticide lindane, which had an estimated 

concentration of 0.006 μg/L (table 2–1). The low-level 

detection of lindane in the blank is not of concern, because 

lindane was not detected in the source-solution blank or in any 

environmental sample. In 1999, Jagucki and Darner (2001) 

found detectable levels of calcium, magnesium, sodium, 

silica, ammonia, orthophosphorous, iron, and boron in blank 

samples. In most cases, concentrations detected in the blanks 

were much less than concentrations in the environmental 

samples, often by two or more orders of magnitude. In no case 

was the concentration in the blank sample large enough to 

substantially affect the concentration of the constituent in the 

environmental samples. 

Stringent equipment-blank procedures were applied to 

bacteria in 1999 and 2009. The sterility of the buffer water 

and the sterilization techniques for the membrane-filtration 

equipment were tested by processing an equipment blank 

before each water sample was filtered. No bacteria were 

detected in any of the equipment blanks in 1999 or 2009. This 

indicates that equipment, supplies, and ambient environmental 

conditions did not bias the bacteria analyses in any way. 
94 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Table 2–1. Chemical characteristics of selected quality-control samples collected in Geauga County, Ohio, June and July 1999 and 

June 2009.

[Abbreviations: <, less than; col/100 mL, colonies per 100 milliliters; E. coli, Escherichia coli; mg/L, milligrams per liter; μg/L, micrograms per liter; REP, 

replicate; BLANK, field blank; SOURCE, source-solution blank; —, not analyzed for; E, estimated value, meaning that the value is lower than the laboratory reporting level but higher than the long-term method detection level for that analyte, as defined by Oblinger Childress and others (1999). An estimated 

(E) concentration has greater uncertainty than that of data reported without the “E” qualifier, but the chance that the analyte is really not present is 1 percent 

or less; boldface type indicates relative differences of 5 percent or greater. Gray shading indicates quality control (QC) samples collected in 2009. Pesticides 

listed in this table are those that were detected in one or more environmental samples. Other analyzed pesticides (listed in appendix table 4–2) were not 

detected in environmental or QC samples.]

Well name Date

Coliform, 

total, water, 

unfiltered 

(col/100 mL)

E. coli,

water, 

unfiltered 

(col/100 mL)

Calcium, 

dissolved 

(mg/L as Ca)

Magnesium, 

dissolved 

(mg/L as Mg)

Potassium, 

dissolved 

(mg/L as K)

Sodium, 

dissolved 

(mg/L as Na)

GE-119 6-17-1999 <1 <1 0.06 0.03 0.2 99

GE-119 REP 6-17-1999 <1 <1 .06 .03 .2 100

GE-165 6-8-1999 <1 <1 63 13 .9 9.0

GE-165 REP 6-8-1999 <1 <1 62 13 .9 8.9

GE-165 6-18-2009 1E <1 65.0 14.6 1.01 10.2

GE-165 REP 6-18-2009 — — 64.6 14.6 1.06 10.3

GE-332 6-18-2009 <1 <1 61.8 17.2 1.58 6.63

GE-332 REP 6-18-2009 — — — — — —

GE-341 6-12-2009 <1 <1 12.8 2.25 1.68 79.2

GE-341 REP 6-12-2009 <1 <1 13.0 2.24 1.73 79.8

GE-349A 7-1-1999 1 <1 26 5.8 1.8 24

GE-349A REP 7-1-1999 1 <1 27 6.0 1.8 25

GE-119 BLANK 6-17-1999 <1 <1 .01E <.004 <.1 .05E

GE-165 BLANK 6-8-1999 <1 <1 .09 .004 <.1 .03E

GE-349A BLANK 7-1-1999 <1 <1 .02 .002E <.1 <.06

GE-349A BLANK 6-8-2009 — — <.02 <.012 <.06 <.12

—

GE-165 SOURCE 6-8-1999 — — — — — —

GE-349A 

SOURCE

7-1-1999 — — — — — —

GE-349A 

SOURCE

6-8-2009 — — — — — —
Appendix 2 95

Table 2–1. Chemical characteristics of selected quality-control samples collected in Geauga County, Ohio, June and July 1999 and 

June 2009.—Continued

[Abbreviations: <, less than; mg/L, milligrams per liter; REP, replicate; BLANK, field blank; SOURCE, source-solution blank; —, not analyzed for; boldface 

type indicates relative differences of 5 percent or greater. Gray shading indicates quality control (QC) samples collected in 2009.]

Well name Date

Bicarbonate, 

water, field 

(mg/L as 

HCO3)

Carbonate, 

water, field 

(mg/L as 

CO3)

Alkalinity, 

water, field 

(mg/L as 

CaCO3)

Sulfide, 

total 

(mg/L as S)

Sulfate, 

dissolved 

(mg/L as SO4)

Chloride, 

dissolved 

(mg/L as 

Cl)

Bromide, 

dissolved 

(mg/L as Br)

Silica, 

dissolved 

(mg/L as 

SiO2)

GE-119 6-17-1999 130 0 110 0.02 70 21 0.02 11

GE-119 REP 6-17-1999 130 0 110 — 70 23 .03 10

GE-165 6-8-1999 200 0 170 .01 37 20 .21 10

GE-165 REP 6-8-1999 200 0 170 .01 37 20 .21 10

GE-165 6-18-2009 215 .3 177 .020 34.7 28.9 .11 11.2

GE-165 REP 6-18-2009 203 .3 167 .024 35.0 29.3 .12 11.2

GE-332 6-18-2009 175 .1 144 <.005 53.2 13.7 .02 9.99

GE-332 REP 6-18-2009 182 .1 150 — — — — —

GE-341 6-12-2009 6.4 0 4.7 <.005 31.6 134 .04 6.50

GE-341 REP 6-12-2009 5.4 0 3.8 <.005 31.9 132 .03 6.57

GE-349A 7-1-1999 42 0 34 <.01 35 43 .05 8.0

GE-349A REP 7-1-1999 40 0 30 <.01 35 43 .06 8.2

GE-119 BLANK 6-17-1999 — — — — <.1 <.1 <.01 <.05

GE-165 BLANK 6-8-1999 — — — — <.1 <.1 <.01 <.05

GE-349A 

BLANK

7-1-1999 — — — — <.1 <.1 <.01 .05

GE-349A 

BLANK

6-8-2009 — — — — <.18 <.12 <.02 <.02

GE-165 

SOURCE 

6-8-1999 — — — — — — — —

GE-349A 

SOURCE 

7-1-1999 — — — — — — — —

GE-349A 

SOURCE

6-28-2009 — — — — — — — —
96 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Table 2–1. Chemical characteristics of selected quality-control samples collected in Geauga County, Ohio, June and July 1999 and 

June 2009.—Continued

[Abbreviations: <, less than; mg/L, milligrams per liter; REP, replicate; BLANK, field blank; SOURCE, source-solution blank; —, not analyzed for; E, estimated 

value, meaning that the value is lower than the laboratory reporting level but higher than the long-term method detection level for that analyte, as defined by 

Childress and others (1999). An estimated (E) concentration has greater uncertainty than that of data reported without the “E” qualifier, but the chance that the 

analyte is really not present is 1 percent or less; boldface type indicates relative differences of 5 percent or greater. Gray shading indicates quality control (QC) 

samples collected in 2009.]

Well name Date

Solids, residue at 180 

degrees 

Celsius, 

dissolved 

(mg/L)

Nitrogen, 

nitrate, 

dissolved 

(mg/L as N)

Nitrate 

+ nitrite, 

dissolved 

(mg/L as N)

Nitrogen, 

nitrite, 

dissolved 

(mg/L as N)

Nitrogen, 

ammonia, 

dissolved 

(mg/L as N)

Nitrogen, 

ammonia + 

organic, 

dissolved 

(mg/L as N)

Phosphorus, 

dissolved 

(mg/L as P)

Orthophosphate, 

dissolved 

(mg/L as P)

GE-119 6-17-1999 283 <0.18 — <0.02 <0.03 <0.005 <0.02 <0.01

GE-119 6-17-1999 287 <.18 — <.02 <.03 <.005 <.02 <.01

GE-165 6-8-1999 272 <.18 — <.02 .04 <.005 <.02 <.01

GE-165 6-8-1999 282 <.18 — <.02 .04 <.005 <.02 <.01

GE-165 6-18-2009 282 — <.04 <.002 .023 <0.10 <.04 <.008

GE-165 6-18-2009 284 — — — — — — —

GE-332 6-18-2009 265 — 1.09 <.002 <.02 <.10 <.04 .008

GE-332 6-18-2009 — — 1.10 <.002 <.02 <.10 <.04 .009

GE-341 6-12-2009 298 — 1.73 <.002 <.02 .07E <.04 .004E

GE-341 6-12-2009 298 — 1.76 <.002 <.02 .05E <.04 .004E

GE-349A 7-1-1999 231 2.2 — <.02 <.03 <.005 <.02 <.01

GE-349A REP 7-1-1999 223 2.4 — <.02 <.03 <.005 <.02 <.01

GE-119 

BLANK 

6-17-1999 <10 <.18 — <.02 <.03 <.005 <.02 .01

GE-165 

BLANK

6-8-1999 <10 <.18 — <.02 .03 <.005 <.02 <.01

GE-349A 

BLANK

7-1-1999 <10 <.18 — <.02 .03 .03 <.02 <.01

GE-349A 

BLANK

6-8-2009 <10 — <.04 <.002 <.10 <.02 <.04 <.008

GE-165 

SOURCE

6-8-1999 — — — — — — — —

GE-349A 

SOURCE 

7-1-1999 — — — — — — — —

GE-349A 

SOURCE

6-8-2009 — — — — — — — —
Appendix 2 97

Table 2–1. Chemical characteristics of selected quality-control samples collected in Geauga County, Ohio, June and July, 1999 and 

June 2009.— Continued

[Abbreviations: <, less than; mg/L, milligrams per liter; μg/L, micrograms per liter; REP, replicate; BLANK, field blank; SOURCE, source-solution blank; 

—, not analyzed for; E, estimated value, meaning that the value is lower than the laboratory reporting level but higher than the long-term method detection 

level for that analyte, as defined by Oblinger Childress and others (1999). An estimated (E) concentration value has greater uncertainty than that of data 

reported without the “E” qualifier, but the chance that the analyte is really not present is 1 percent or less; boldface type indicates relative differences of 5 

percent or greater. Gray shading indicates quality control (QC) samples collected in 2009. Pesticides listed in this table are those that were detected in one or 

more environmental samples. Other pesticides analyzed (listed in appendix table 4–2) were not detected in environmental or QC samples.]

Well name Date

Arsenic, 

dissolved 

(μg/L as 

As)

Iron, 

dissolved 

(μg/L

as Fe)

Manganese, 

dissolved 

(μg/L as Mn)

Carbon, 

organic, 

dissolved 

(mg/L as C)

Atrazine, 

dissolved

(μg/L)

CIAT,

dissolved

(μg/L)

Lindane, 

dissolved

(μg/L)

Methane, 

dissolved 

gas

(mg/L)

GE-77 6-16-2009 — — — — — — — 0.0071

GE-77 REP 6-16-2009 — — — — — — — .0065

GE-119 6-17-1999 — 18 6 0.9 — — — —

GE-119 REP 6-17-1999 — 21 6 .8 — — — —

GE-126 6-17-2009 — — — — — — — .9351

GE-126 REP 6-17-2009 — — — — — — — .9918

GE-147 6-16-2009 — — — — — — — 1.85

GE-147 REP 6-16-2009 — — — — — — — 1.88

GE-165 6-8-1999 — 1,900 180 .3 — — — —

GE-165 REP 6-8-1999 — 1,800 180 .3 — — — —

GE-165 6-18-2009 2.3 1,980 188 .4E <.007 <.014 <.014 —

GE-165 REP 6-18-2009 2.2 1,960 187 .4E — — — —

GE-332 6-18-2009 .10 4E .2 .6 <.007 <.014 <.014 —

GE-332 REP 6-18-2009 — — — — <.007 <.014 <.014 —

GE-341 6-12-2009 .06E 7 87.4 .6 .007 .006E <.014 —

GE-341 REP 6-12-2009 .06E 6 88.9 .6 .008 .006E <.014 —

GE-349A 7-1-1999 — 15 <3 .8 — — — —

GE-349A REP 7-1-1999 — 19 2E .8 — — — —

GE-119 

BLANK 

6-17-1999 — <10 <3 <.1 — — — —

GE-165 

BLANK

6-8-1999 — <10 <3 <.1 — — — —

GE-349A 

BLANK

7-1-1999 — 6E <3 <.1 — — — —

GE-349A 

BLANK

6-8-2009 <.06 <4 <.2 <.4 <.007 <.014 .0061 —

GE-165 

SOURCE

6-8-1999 — — — <.1 — — — —

GE-349A 

SOURCE 

7-1-1999 — — — .2 — — — —

GE-349A 

SOURCE

6-8-2009 — — — <.4 <.007 <.014 <.014 —

1

The detected concentration was below the National Water Quality Laboratory’s long-term method detection level as defined by Oblinger Childress and others 

(1999) for lindane in 2009 and thus has a level of uncertainty greater than that for estimated values. 
98 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Assessing holding time violations and identifying analytes 

that may be subject to degradation.—To ensure minimal 

degradation of sensitive constituents between the times of 

sample collection and analysis, pH, dissolved oxygen, sulfide, 

alkalinity, and bacteria concentrations were analyzed in the 

field. Samples for other degradation-prone constituents—

nutrients, DOC, and pesticides—were chilled and shipped to 

the laboratory as soon as possible, and holding times (time 

between sample collection and sample extraction or analysis) 

were monitored. In 2009, all samples for nutrients and DOC 

were analyzed within the maximum holding times of 30 days 

and 28 days, respectively. However, three pesticide samples 

(GE-77, GE-141, and GE-147), exceeded the maximum 

holding time of 7 days (from sampling to extraction). 

Holding times for these samples were 8 days, based on 

sample preparation records at the National Water Quality 

Laboratory. According to Duane Wydoski, Supervisory 

Chemist at the laboratory (2010, written commun. on file at 

the USGS Ohio Water Science Center in Columbus, Ohio), a 

review of available holding-time studies (Zaugg and others, 

1995; Sandstrom and others, 2001; and one unpublished 

2004 study) indicates that two of the pesticides analyzed for 

would have degraded somewhat after 6 or 7 days. These two 

compounds are alpha-endosulfan and malathion; most of the 

other pesticides would not be affected by the holding-time 

exceedance.

Assessing laboratory bias and variability over time 

(between sampling rounds).—To determine and track the 

degree of uncertainty associated with the measured values 

of chemical concentration over time, the Branch of Quality 

Systems operates independent, external, blind sample projects 

for both inorganic (Inorganic Blind Sample Project) and 

organic (Organic Blind Sample Project) constituents (U.S. 

Geological Survey, 2010). Through these projects, “blind” QA 

samples are submitted for analysis, meaning that concentration 

levels in the samples are unknown to the analyst. For the 

inorganic blind samples, the identity of the samples is 

unknown as well (“double blind”). Blind QA samples contain 

selected inorganic, organic, and nutrient constituents at various 

concentrations and are disguised as routine environmental 

samples. Staff of the blind sample projects take the constituent 

concentration measured by the NWQL in the blind QA sample, 

divide by the expected concentration, and multiply by 100 to 

get a percent recovery. Percent recovery is then plotted over 

time (fig. 2–1) to determine laboratory bias and variability. 

A long-term positive bias in percent recovery as viewed on 

a time-series chart means that if the laboratory analyzed the 

same sample each year (and the sample did not degrade), that 

each year the laboratory would report a higher than actual 

concentration of the analyte in that sample. Blind-sample data 

for many inorganic constituents are available from 1984 to 

present. Blind-sample data for organic constituents may go 

back as far as the mid- to late 1990s.

To determine whether the changes in constituent 

concentrations observed between 1986 and 1999 (table 8A) 

or 1999 and 2009 in samples from Geauga County (table 8B) 

were greater than changes expected due to laboratory recovery, 

blind-sample project data were used to calculate the median 

percent recovery for each constituent of interest for a 3-month 

period (shown as gray shading in fig. 2–1) centered on the date 

of sampling for the 1999 and 2009 sampling rounds (or, in the 

case of chloride, for a 3-month period centered on the date 

of sampling for the 1986 and 1999 sampling rounds1). The 

median constituent concentration measured in 1999 (in paired 

wells only) was then multiplied by the ratio of the median 

2009 recovery to the median 1999 recovery to calculate the 

expected median concentration in 2009 if concentration 

differences were due solely to changes in laboratory recovery 

over time (table 2–2)2. For chloride, magnesium, and 

organic carbon, the actual median concentration in 2009 (or 

for chloride, in 1999) in paired wells, taking into account 

sampling and laboratory variability as indicated by replicate 

samples (last column, table 2–2) was appreciably different 

than the expected median concentration based on laboratory 

recovery alone (table 2–2). Thus, the observed changes 

over time in concentrations of these constituents likely are 

not caused solely by changes in recovery and sampling 

and laboratory variability. In contrast, the expected median 

concentration for silica in 2009 was 13.0 mg/L (based solely 

on laboratory recovery); this fell within the range of the actual 

(measured) median concentration plus or minus maximum 

difference in replicate samples (12.2–14.2 milligrams per 

liter, table 2–2). Thus, the difference in silica concentrations 

between 1999 and 2009, although statistically significant 

(table 8B), may not result from a change in the groundwater 

chemistry over time but instead may be caused by laboratory 

bias.

Because the Inorganic Blind Sample Project did not 

begin collecting blind-sample results for bromide until 

2010, expected variations in measured concentration caused 

by changes in laboratory recovery could not be calculated. 

However, to obtain the bromide concentrations observed 

in 2009 given 1999 concentrations (and calculated as if 

the change from 1999 to 2009 were a result of changes in 

laboratory recovery alone) would require a recovery ratio 

of 0.50, which is much smaller than recovery ratios for 

other constituents in table 2–2 and would be outside of the 

typical range of recovery ratios (0.90 to 1.10) expected for 

concentrations well above the long-term method detection 

level (Tedmund Struzeski, 2011, written commun. on file at 

the USGS Ohio Water Science Center in Columbus). Thus, 

observed changes in bromide concentration over time likely 

result from actual changes in groundwater chemistry. Because 

1

The calculation of median percent recovery for each date range was 

limited to laboratory spike concentrations equal to the range of concentrations 

measured in environmental samples plus or minus 4 milligrams per liter.

2

This comparison of environmental sample concentrations to blind-sample 

recoveries assumes that the effect of the sample matrix on analytical results 

is similar for both environmental and blind samples. (The inorganic blind 

samples are derived from natural surface-water sources.)
Appendix 2 99

60

70

80

90

100

110

120

130

140

1983 1987 1991 1995 1999 2003 2007 2011

Percent recovery

Date logged in

Magnesium, water, filtered (P00925)

1999

2009

0

50

100

150

200

1983 1987 1991 1995 1999 2003 2007 2011

Percent recovery

Date logged in

Chloride, water, filtered (P00940)

1986

1999

2009

Fig 2-1 rst two parts of four

Figure 2–1. Changes in percent recovery over time for selected constituents analyzed by the National Water Quality Laboratory. 

(Shaded gray bands indicate a 3-month period centered on the date of each groundwater-sampling round. Number in parentheses 

is the laboratory parameter code.)
100 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

40

60

80

100

120

140

160

180

200

1983 1987 1991 1995 1999 2003 2007 2011

Percent recovery

Date logged in

Organic carbon, water, filtered (P00681)

1999

2009

Fig 2-1 second part

0

50

100

150

200

1983 1987 1991 1995 1999 2003 2007 2011

Percent recovery

Date logged in

Silica, water, filtered (P00955)

1999

1986

2009

Figure 2–1. Changes in percent recovery over time for selected constituents analyzed by the National Water Quality Laboratory. 

(Shaded gray bands indicate a 3-month period centered on the date of each groundwater-sampling round. Number in parentheses is the 

laboratory parameter code.)—Continued
Appendix 2 101

Table 2–2. Expected median constituent concentrations in paired wells in 2009 based on laboratory percent recovery ratios 2009:1999. [NA, not available; mg/L, milligrams per liter. Constituents listed are those analyzed by the National Water Quality Laboratory in both 1999 and 2009 and for which a statistically significant (p-value <0.05) difference in concentration was observed between 1999 and 2009 (table 8). For each sampling round, median percent recovery was determined for the 4 weeks before sampling, the 2–4 weeks during sampling, and for 6 weeks after sampling. Thus, median percent recovery for the 1999 sampling round was determined for sample log-in dates of May 10 through August 17, 1999; median percent recovery for 2009 was determined for sample log-in dates of May 11 through August 1, 2009. The calculation of median percent recovery for each date range was also limited to spike concentrations equal to the range of concentrations measured in environmental samples plus or minus 4 milligrams per liter. The recovery ratio listed in red is a theoretical value (because actual recovery data for these years were not available) calculated as if the difference in measured concentrations between 1999 and 2009 was due solely to changes in laboratory recovery over time. Values in [brackets] represent 1986 data rather than 1999 data. Values in {braces} represent 1999 data rather than 2009 data. All actual median concentrations are calculated only for paired wells that were resampled in 1986 and 1999 or in 1999 and 2009.]

Constituent

Median percent 

recovery, 

1999

Median percent 

recovery, 

2009

Recovery 

ratio, 

2009:1999

Median 

measured 

concentration, 

1999 (mg/L)

Expected median 

concentration, 

2009 (mg/L)

(if change is solely 

due to lab recovery)

Actual median 

(measured) 

concentration, 

2009 (mg/L)

Maximum 

difference 

in replicate 

samples 

(1999 and 2009)

Actual median 

concentration, 2009 

(mg/L) ± maximum 

difference in 

replicate samples

Chloride1 [99.45] {100.56} {[1.011]} [2.9] {2.9} {8.13} 2 {6.13−10.13}Magnesium 98.32 97.45 .9912 16.2 16.0 17.4 .2 17.2−17.6Silica 99.45 100.78 1.013 12.8 13.0 13.2 1 12.2−14.2Bromide NA NA .502 .04 NA .02 .01 .01−.03Organic 

carbon 109.473 102.16 .9332 .7 .7 .4 .1 .3−.5

1Chloride data are for 1986 and 1999 rather than 1999 and 2009.2 Calculated theoretical value—a recovery ratio of 0.50 would be required to account for the difference in the 1999 median measured bromide concentration (0.04 mg/L) and the 2009 

median measured concentration (0.02 mg/L) if difference was due to laboratory recovery alone.

3The blind sample project had no percent recovery data for organic carbon in 1999. Instead, the median of the last four percent-recovery values for 1998 (July 1 through September 24, 

1998) and the first four values for 2001 (June 16 through August 9, 2001) was calculated after further limiting the dataset to spike values that were equal to the range of values observed in the environmental samples plus or minus 4 mg/L.
102 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

ammonia analyses were done by Heidelberg University 

laboratory (rather than the NWQL) in 1999, it was not 

appropriate to assess laboratory bias and variability over time 

for ammonia using typical NWQL recovery ratios.

Percent recovery data do not exist for other properties 

and constituents with statistically significant changes in 

concentration over time—dissolved oxygen, pH, specific 

conductance, and alkalinity—because these concentrations 

were measured in the field rather than in the laboratory. 

However, field instruments were calibrated daily during the 

sample collection period and were not prone to excessive drift. 

Additionally, the dissolved oxygen meter was tested at the 

end of the sampling round and accurately measured a lowdissolved oxygen calibrant that was not available in the field. 

Lastly, the field analysts and instruments had passed annual 

tests of proficiency as part of the Branch of Quality Systems 

National Field Quality Assurance Project. For three of the field 

parameters, the changes in sample measurements from 1999 

to 2009 were compared relative to stabilization criteria for 

recording field measurements, as specified in the USGS Field 

Manual (U.S. Geological Survey, 1997–present) and as shown 

in table 2–3. (Stabilization criteria have not been established 

for alkalinity.) These stabilization criteria reflect “the accuracy 

that should be obtainable with a calibrated instrument” 

that has equilibrated to the temperature of the water being 

sampled, given “the natural variability inherent in...

groundwater” pumped through a flowthrough chamber at the 

time of sampling. Median concentrations of dissolved oxygen 

and pH for environmental samples in 2009 were outside 

of the range of 1999 median concentrations plus or minus 

the stabilization criteria (table 2–3). Thus, the statistically 

significant differences in concentrations of these constituents 

from 1999 to 2009 (table 8B) likely represent actual changes 

in groundwater chemistry. However, median specific 

conductance for environmental samples in 2009 is within the 

range of the 1999 median value plus or minus the stabilization 

criteria (table 2–3), suggesting that the differences listed in 

table 8B may represent instrument variability rather than a 

change in groundwater chemistry.

Table 2–3. Comparison of median values of dissolved oxygen, pH, and specific conductance in 2009 to expected variation 

in 1999 median values caused by measurement stabilization for 16 paired wells.

[mg/L, milligrams per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius. Stabilization criteria are from U.S. Geological Survey, 

1997–present]

Constituent Stabilization

criterion

Median value

1999

Median value 1999 +

stabilization criterion

Median value 

2009

Dissolved oxygen (mg/L) ± 0.3 mg/L 0.1 0–0.4 1.05

pH ± 0.1 7.4 7.3–7.5 7.2

Specific conductance (μS/cm) ± 3 percent 500 485–515 509
Appendix 3 103

Appendix 3. Land Cover and Population Upgradient of Each Well

Table 3–1. Land-cover types, population, number of acres permitted for biosolids spreading, and number of producing oil and gas 

wells upgradient of 16 domestic wells sampled in 2009, and 7 selected water-supply well fields in Geauga County, Ohio.

[—, no permitted biosolids spreading or producing oil and gas wells located upgradient of well. Characteristics shown in table are within a 500 meter-radius 

quarter circle oriented hydraulically upgradient of the well. Data sources are as follows: Percent land cover types, 2001 National Land Cover Database (Homer 

and others, 2007); number of people, U.S. Census Bureau (2010); number of acres permitted for biosolids application, Ohio Environmental Protection Agency 

(2010a); number of producing oil and gas wells, Ohio Department of Natural Resources (2008a)]

Well 

name

Percent land-cover types 

Number 

of people 

(year 2000)

Number 

of acres 

permitted 

for 

biosolids 

spreading

Number of 

producing 

oil and 

gas wells Developed Water Forest Shrub/

Scrub

GrasslandAgriculture Wetland

Domestic wells

GE-77 45.83 0 43.98 0 10.19 0 0 34 — —

GE-85A 58.37 0 14.48 0 11.31 15.84 0 7 — —

GE-103 13.55 0 7.01 0 1.87 77.10 0.47 12 — 1

GE-108 20.18 0 79.82 0 0 0 0 12 — —

GE-109 4.07 0 50.23 0 1.36 44.34 0 20 — —

GE-120 24.66 0 33.79 0 41.55 0 0 31 — —

GE-126 37.90 0 29.22 0 4.57 28.31 0 17 — —

GE-141 9.09 0 21.36 0 0 69.55 0 20 9.91 —

GE-147 51.60 0 1.83 0 0 46.58 0 15 — —

GE-151 7.34 0 60.55 0 21.10 11.01 0 14 — —

GE-165 16.97 0 0.46 0 0 82.57 0 22 — —

GE-185A 33.93 0 34.82 0 8.04 23.21 0 26 — —

GE-202 4.11 2.74 59.36 0 0 33.79 0 7 — —

GE-234 29.30 0 38.60 0 0 31.16 0.93 10 — —

GE-332 66.67 0 26.48 0 0.91 5.94 0 69 — —

GE-341 0.46 0 2.28 0 5.48 91.78 0 3 — —

Public-supply wells

ASM 

International

43.38 0 56.62 0 0 0 0 23 — —

Burton 

Village

1.37 16.89 42.47 2.28 0.91 0 36.07 1 — —

Chardon 

City

39.81 0 52.31 3.70 0 0 4.17 14 — —

Christ 

Presbyterian

90.41 0 9.13 0 0.46 0 0 58 — 1

Lake 

Lucerne

86.76 0 10.05 0 3.20 0 0 177 — —

Middlefield 

Village

12.27 0 0 0 5.91 81.82 0 8 — —

Tanglewood 

Lake

26.36 0 31.36 0 0 42.27 0 47 — 1
104 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Appendix 4. Water-Quality Data

Well-selection notes: Samples that were determined to have passed through household water softeners were removed from 

the dataset of all water samples collected by the U.S. Gelolgical survey in Geauga County, Ohio, 1978–2009 (fig. 4-1 and table 

4-1). Samples from 1986 that specifically targeted brines and wells suspected by homeowners to be brine contaminated were 

also removed. Additionally, wells completed solely in the Bedford Shale underlying the Berea Sandstone were removed from the 

dataset because this is not one of the four primary aquifers used in the county. 

Figures

4–1. Locations of wells sampled by the U.S. Geological Survey in Geauga County, Ohio, 1978–2009..................................105 

Tables

4–1. Selected chemical characteristics of water samples collected by the U.S. Geological Survey in Geauga County, 

Ohio, 1978–2009. (Table, in Excel format, is available at http://dx.doi.org/10.3133/sir20155032)

4–2. Pesticides analyzed for in groundwater samples from 16 domestic wells in Geauga County, June 2009...................106

4–3. Volatile organic compounds and semivolatile organic compounds analyzed for in groundwater samples in 

Geauga County, Ohio, 1995–2009 ..........................................................................................................................................................108 
Appendix 4 105

Chagrin River

Cuyahoga River

Grand River

GE-101

GE-102

GE-103

GE-104 GE-105

GE-108

GE-109

GE-111

GE-112

GE-115

GE-116

GE-120

GE-122

GE-141 GE-126

GE-147

GE-151

GE-157

GE-159

GE-165

GE-169

GE-174

GE-174A

GE-175

GE-180

GE-185A

GE-186

GE-18Q

GE-204

GE-20Q

GE-234

GE-235

GE-321

GE-34

GE-341

GE-37

GE-39

GE-42

GE-44

GE-48

GE-49

GE-53Q

GE-55

GE-60

GE-61

GE-67

GE-68

GE-69

GE-73

GE-77

GE-81Q

GE-85

GE-85A

GE-86

GE-89

GE-92

GE-95

GE-119

GE-202

GE-23

GE-280

GE-332

GE-349A

GE-355

GE-228

81°10'

81°20'

41°40'

41°30'

Figure 4-1.

Base from U.S. Geological Survey

1:24,000 digital data

Universal Transverse Mercator, zone 17

EXPLANATION

GE-77 Water-quality site and well 

name

Cleveland

0 5 MILES

0 5 KILOMETERS

Figure 4–1. Locations of wells sampled by the U.S. Geological Survey in Geauga County, Ohio, 1978–2009.
106 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Table 4–2. Pesticides analyzed for in groundwater samples from 16 domestic wells in Geauga County, June 2009.—Continued

[MCL, Maximum Contaminant Level; HA-L, lifetime health advisory; HA-C, 10−6 cancer risk concentration; μg/L, micrograms per liter; —, no benchmark 

available. Human-health benchmarks are defined in sidebar, p.27, and are from http://water.usgs.gov/nawqa/pnsp/benchmarks/ (searchable online database for 

Health-Based Screening Levels, updated Feb. 28, 2012). This table is modified from DeSimone and others, 2009, table 4–1.]

Pesticide compound

(dissolved)

Type of pesticide 

compound (parent 

pesticide, if degradate)

Human-health benchmarks Laboratory 

reporting level, 

in micrograms 

per liter (μg/L)

Number of 

detections Source Value (μg/L)

2,6-Diethylaniline Degradate (Alachlor) — — 0.006 0

2-Chloro-4-isopropylamino-6-

amino-s-trianzine (CIAT)

Degradate (Atrazine) — — .014 11

Acetochlor Herbicide HA-C 10 .01 0

Alachlor Herbicide MCL 2 .008 0

alpha-HCH Degradate (Lindane) HA-C .006 .008 0

Atrazine Herbicide MCL 3 .007 1

Azinphos-methyl (Guthion) Insecticide HA-L 10 .12 0

Benfluralin Herbicide HA-L 4 .014 0

Butylate Herbicide HA-L 400 .002 0

Carbaryl Insecticide HA-C 40 .2 0

Carbofuran Insecticide MCL 40 .06 0

Chlorpyrifos Insecticide HA-L 2 .012 0

cis-Permethrin Insecticide HA-C 4 .014 0

Cyanazine Herbicide HA-L 1 .04 0

Dacthal (DCPA) Herbicide HA-L 70 .006 0

Desulfinyl-fipronil Degradate (Fipronil) — — .012 0

Diazinon Insecticide HA-L 1 .005 0

Dieldrin Insecticide, Degradate 

(Aldrin)

HA-C .002 .009 0

Disulfoton Insecticide HA-L .9 .04 0

EPTC Herbicide HA-L 200 .002 0

Ethalfluralin Herbicide HA-L 30 .009 0

Ethoprop (Ethoprophos) Herbicide HA-C 1 .016 0

Desulfinylfipronil amide Degradate (Fipronil) — — .029 0

Fipronil sulfide Degradate (Fipronil) — — .013 0

Fipronil sulfone Degradate (Fipronil) — — .024 0

Fipronil Insecticide HA-L .1 .04 0

Fonofos Insecticide HA-L 10 .01 0

Lindane (gamma-HCH) Insecticide MCL .2 .014 0
Appendix 4 107

Table 4–2. Pesticides analyzed for in groundwater samples from 16 domestic wells in Geauga County, June 2009.—Continued

[MCL, Maximum Contaminant Level; HA-L, lifetime health advisory; HA-C, 10−6 cancer risk concentration; μg/L, micrograms per liter; —, no benchmark 

available. Human-health benchmarks are defined in sidebar, p.27, and are from http://water.usgs.gov/nawqa/pnsp/benchmarks/ (searchable online database for 

Health-Based Screening Levels, updated Feb. 28, 2012). This table is modified from DeSimone and others, 2009, table 4–1.]

Pesticide compound

(dissolved)

Type of pesticide 

compound (parent 

pesticide, if degradate)

Human-health benchmarks Laboratory 

reporting level, 

in micrograms 

per liter (μg/L)

Number of 

detections Source Value (μg/L)

Linuron Herbicide HA-L 5 0.06 0

Malathion Insecticide HA-L 500 .02 0

Methyl parathion Insecticide HA-L 1 .008 0

Metolachlor Herbicide HA-L 700 .014 0

Metribuzin Herbicide HA-L 90 .016 0

Molinate Herbicide HA-L .7 .002 0

Napropamide Herbicide HA-L 800 .018 0

p,p′-DDE Degradate (p,p′-DDT) HA-C .1 .003 0

Parathion (Ethyl parathion) Insecticide HA-L .02 .02 0

Pebulate Herbicide HA-L 50 .016 0

Pendimethalin Herbicide HA-L 20 .012 0

Phorate Insecticide HA-L 4 .02 0

Prometon Herbicide HA-L 400 .012 0

Propyzamide (Pronamide) Herbicide HA-C 1 .004 0

Propachlor Herbicide HA-C 1 .012 0

Propanil Herbicide HA-L 6 .014 0

Propargite Acaricide HA-C 1 .02 0

Simazine Herbicide MCL 4 .01 0

Tebuthiuron Herbicide HA-L 1,000 .02 0

Terbacil Herbicide HA-L 100 .04 0

Terbufos Insecticide HA-L .4 .018 0

Thiobencarb Herbicide HA-L 70 .016 0

Triallate Herbicide HA-L 20 .006 0

Trifluralin Herbicide HA-L 20 .012 0

1

 This detection was an estimated concentration that was below the long-term method detection level (LT-MDL). Unlike other reported concentrations, there is 

less than 99 percent confidence that this analyte concentration is greater than zero.

2

 An interim reporting level was used for chlorpyrifos, because the analytical method did not have at least one year’s worth of supporting data to determine 

a LT-MDL and corresponding laboratory reporting level (calculated as the LT-MDL multiplied by two). The interim reporting level is at least two times the 

estimated detection limit.
108 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Table 4–3. Volatile organic compounds and semivolatile organic compounds analyzed for in groundwater samples in Geauga County, 

Ohio, 1995–2009.

[USGS, water samples from 31 domestic wells analyzed by U.S. Geological Survey personnel in 1999 (Jaguck and Darner, 2001); Public-supply well data 

were compiled from Ohio Environmental Protection Agency’s Ambient Ground Water Monitoring Well Network program (untreated water samples from ASM 

International, Middlefield Village, and Tanglewood Lake) and compliance data from public-supply wells submitted to Ohio Environmental Protection Agency’s 

Safe Drinking Water Information System database (untreated and treated water samples from Burton Village, Chardon City; Christ Presbyterian Church, Lake 

Lucerne Club Co., Middlefield Village; and Tanglewood Lake Water Co.). Locations of public-supply wells are shown in fig. 12; well identifiers and corresponding public-supply well names are listed in table 4. Orange shading indicates the compound is produced as a byproduct of drinking-water chlorination; ●, 

analyzed for but not detected1; ▲, detected in some samples.]

Volatile organic compounds

Domestic 

wells 

(untreated 

water)

Public-supply wells

Untreated water Treated water

USGS

ASM International 

Lake Lucerne

Middlefield Village

Tanglewood Lake

Burton Village

Chardon

Christ Presbyterian

Lake Lucerne

Middlefield Village

Tanglewood Lake

1,1,1,2-Tetrachloroethane ● ● ● ● ● ● ● ● ●

1,1,1-Trichloroethane ● ● ● ● ● ● ● ● ●

1,1,2,2-Tetrachloroethane ● ● ● ● ● ● ● ● ●

1,1,2-Trichloroethane ● ● ● ● ● ● ● ● ●

1,1-Dichloroethane (DCA) ● ● ● ● ● ● ● ● ●

1,1-Dichloroethylene ● ● ● ● ● ● ● ● ●

1,1-Dichloropropene ● ● ● ● ● ● ● ● ●

1,2,3-Trichlorobenzene ● ● ● ● ● ● ● ● ●

1,2,3-Trichloropropane ● ● ● ● ● ● ● ● ●

1,2,4-Trichlorobenzene ● ● ● ● ● ● ● ● ●

1,2,4-Trimethylbenzene ● ● ● ● ● ● ● ● ●

1,2-Dibromo-3-chloropropane ●

1,2-Dichlorobenzene ●

1,2-Dichloroethane ● ● ● ● ● ● ● ● ●

1,2-Dichloropropane ● ● ● ● ● ● ● ● ●

1,3,5-Trimethylbenzene ● ● ● ● ● ● ● ● ●

1,3-Dichlorobenzene ●

1,3-Dichloropropane ● ● ● ● ● ● ● ● ●

1,3-Dichloropropene ● ● ● ● ● ● ● ●

2,2-Dichloropropane ● ● ● ● ● ● ● ● ●

2-Chlorotoluene ●

4-Chlorotoluene ●

4-Isopropylmethylbenzene ●

Acetone ● ●

Benzene ● ● ● ● ● ● ● ● ● ● ●

Bromobenzene ● ● ● ● ● ● ● ● ●

Bromochloromethane 

(Chlorobromomethane)

● ● ● ● ● ● ● ● ●
Appendix 4 109

Table 4–3. Volatile organic compounds and semivolatile organic compounds analyzed for in groundwater samples in Geauga County, 

Ohio, 1995–2009.—Continued

[USGS, water samples from 31 domestic wells analyzed by U.S. Geological Survey personnel in 1999 (Jaguck and Darner, 2001); Public-supply well data 

were compiled from Ohio Environmental Protection Agency’s Ambient Ground Water Monitoring Well Network program (untreated water samples from ASM 

International, Middlefield Village, and Tanglewood Lake) and compliance data from public-supply wells submitted to Ohio Environmental Protection Agency’s 

Safe Drinking Water Information System database (untreated and treated water samples from Burton Village, Chardon City; Christ Presbyterian Church, Lake 

Lucerne Club Co., Middlefield Village; and Tanglewood Lake Water Co.). Locations of public-supply wells are shown in fig. 12; well identifiers and corresponding public-supply well names are listed in table 4. Orange shading indicates the compound is produced as a byproduct of drinking-water chlorination; ●, 

analyzed for but not detected1; ▲, detected in some samples.]

Volatile organic compounds

Domestic 

wells 

(untreated 

water)

Public-supply wells

Untreated water Treated water

USGS

ASM International 

Lake Lucerne

Middlefield Village

Tanglewood Lake

Burton Village

Chardon

Christ Presbyterian

Lake Lucerne

Middlefield Village

Tanglewood Lake

Bromodichloromethane ● ▲ ● ▲ ▲ ● ▲ ▲ ▲

Bromomethane 

(Methyl bromide)

● ● ● ● ● ● ● ● ●

Chlorobenzene ● ● ● ● ● ● ● ● ●

Chloroethane ● ● ● ● ● ● ● ● ●

Chloromethane (Methyl chloride)

● ● ● ● ● ● ● ● ●

cis-1,2-Dichloroethylene 

(cis-1,2-Dichloroethene)

● ● ● ● ● ● ● ● ●

cis-1,3-Dichloropropene ●

Dibromoacetic acid ▲ ▲ ▲ ▲ ▲ ▲

Dibromochloromethane 

(Chlorodibromomethane)

● ▲ ● ▲ ▲ ● ▲ ▲ ▲

Dibromomethane ● ● ● ● ● ● ● ● ●

Dichloroacetic acid ● ● ● ● ▲ ▲ ▲

Dichlorodifluoromethane 

(CFC-12, Freon-12)

● ● ● ● ● ● ● ● ●

Dichloromethane (Methylene 

chloride)

● ● ● ● ● ● ● ● ●

Ethylbenzene ● ● ● ● ● ● ● ● ●

Ethylene dibromide (EDB, 

dibromomethane)

●

Hexachlorobutadiene ● ● ● ● ● ● ● ● ●

Hexachloroethane ●

Isopropylbenzene (Cumene) ● ● ● ● ● ● ● ●

m-Dichlorobenzene ● ● ● ● ● ● ● ●

Methyl tert-butyl ether (MTBE) ● ● ● ● ● ● ● ● ●

Monobromoacetic acid ● ● ● ● ●
110 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Table 4–3. Volatile organic compounds and semivolatile organic compounds analyzed for in groundwater samples in Geauga County, 

Ohio, 1995–2009.—Continued

[USGS, water samples from 31 domestic wells analyzed by U.S. Geological Survey personnel in 1999 (Jaguck and Darner, 2001); Public-supply well data 

were compiled from Ohio Environmental Protection Agency’s Ambient Ground Water Monitoring Well Network program (untreated water samples from ASM 

International, Middlefield Village, and Tanglewood Lake) and compliance data from public-supply wells submitted to Ohio Environmental Protection Agency’s 

Safe Drinking Water Information System database (untreated and treated water samples from Burton Village, Chardon City; Christ Presbyterian Church, Lake 

Lucerne Club Co., Middlefield Village; and Tanglewood Lake Water Co.). Locations of public-supply wells are shown in fig. 12; well identifiers and corresponding public-supply well names are listed in table 4. Orange shading indicates the compound is produced as a byproduct of drinking-water chlorination; ●, 

analyzed for but not detected1; ▲, detected in some samples.]

Volatile organic compounds

Domestic 

wells 

(untreated 

water)

Public-supply wells

Untreated water Treated water

USGS

ASM International 

Lake Lucerne

Middlefield Village

Tanglewood Lake

Burton Village

Chardon

Christ Presbyterian

Lake Lucerne

Middlefield Village

Tanglewood Lake

Monochloroacetic acid ● ● ● ▲ ● ▲

n-Butylbenzene (Butylbenzene) ● ● ● ● ● ● ● ● ●

n-Propylbenzene ● ● ● ● ● ● ● ● ●

Naphthalene ● ● ● ● ● ● ● ● ●

o-Chlorotoluene ● ● ● ● ● ● ● ●

o-Dichlorobenzene ● ● ● ● ● ● ● ●

p-Chlorotoluene ● ● ● ● ● ● ● ●

p-Dichlorobenzene ● ● ● ● ● ● ● ●

p-Isopropyltoluene ● ● ● ● ● ● ● ●

sec-Butylbenzene ● ● ● ● ● ● ● ● ●

Styrene ● ● ● ● ● ● ● ● ●

tert-Butylbenzene ● ● ● ● ● ● ● ● ●

Tetrachloroethylene (Tetrachloroethene, Perchloroethylene, 

PCE)

● ● ● ● ● ● ● ● ● ● ●

Tetrachloromethane (Carbon 

tetrachloride, Freon 10)

● ● ● ● ● ● ● ● ●

Toluene ● ● ● ● ● ● ● ● ● ● ●

Total haloacetic acids ▲ ▲ ▲ ▲ ▲ ▲

trans-1,2-Dichloroethene 

(trans-1,2-Dichlroethylene)

● ● ● ● ● ● ● ● ●

trans-1,3-Dichloropropene ● ●

Tribromomethane (bromoform) ● ▲ ● ▲ ▲ ● ▲ ▲ ▲

Trichloroacetic acid ● ● ● ▲ ▲ ▲

Trichloroethene 

(Trichlorethylene, TCE)

● ● ● ● ● ● ● ● ● ● ●
Appendix 4 111

Table 4–3. Volatile organic compounds and semivolatile organic compounds analyzed for in groundwater samples in Geauga County, 

Ohio, 1995–2009.—Continued

[USGS, water samples from 31 domestic wells analyzed by U.S. Geological Survey personnel in 1999 (Jaguck and Darner, 2001); Public-supply well data 

were compiled from Ohio Environmental Protection Agency’s Ambient Ground Water Monitoring Well Network program (untreated water samples from ASM 

International, Middlefield Village, and Tanglewood Lake) and compliance data from public-supply wells submitted to Ohio Environmental Protection Agency’s 

Safe Drinking Water Information System database (untreated and treated water samples from Burton Village, Chardon City; Christ Presbyterian Church, Lake 

Lucerne Club Co., Middlefield Village; and Tanglewood Lake Water Co.). Locations of public-supply wells are shown in fig. 12; well identifiers and corresponding public-supply well names are listed in table 4. Orange shading indicates the compound is produced as a byproduct of drinking-water chlorination; ●, 

analyzed for but not detected1; ▲, detected in some samples.]

Volatile organic compounds

Domestic 

wells 

(untreated 

water)

Public-supply wells

Untreated water Treated water

USGS

ASM International 

Lake Lucerne

Middlefield Village

Tanglewood Lake

Burton Village

Chardon

Christ Presbyterian

Lake Lucerne

Middlefield Village

Tanglewood Lake

Trichlorofluoromethane 

(CFC-11)

● ● ● ● ● ● ● ● ●

Trichloromethane (chloroform) ● ▲ ● ● ▲ ● ▲ ▲ ▲

Trihalomethanes 

(unspecified mix)

● ▲

Total trihalomethanes (TTHM) ▲ ▲ ▲ ▲ ▲

Vinyl chloride ● ● ● ● ● ● ● ● ●

Xylene ●

o-Xylene ● ● ●

m-& p-Xylenes ● ● ● ●

Total xylenes ● ● ● ● ● ▲ ● ●

Semivolatile organic 

compounds 

2-Chloronaphthalene ●

2-Chlorophenol ●

2-Nitrophenol ●

2,4-Dichlorophenol ●

2,4-Dimethylphenol ●

2,4-Dinitrophenol ●

2,4-Dinitrotoluene ●

2,6-Dinitrotoluene ●

2,4,6-Trichlorophenol (TCPh) ●

4-Bromophenyl-phenylether ●

4-Chloro-3-methylphenol ●

4-Chlorophenyl-phenylether ●

Acenaphthene ●

Acenaphthylene ●
112 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Table 4–3. Volatile organic compounds and semivolatile organic compounds analyzed for in groundwater samples in Geauga County, 

Ohio, 1995–2009.—Continued

[USGS, water samples from 31 domestic wells analyzed by U.S. Geological Survey personnel in 1999 (Jaguck and Darner, 2001); Public-supply well data 

were compiled from Ohio Environmental Protection Agency’s Ambient Ground Water Monitoring Well Network program (untreated water samples from ASM 

International, Middlefield Village, and Tanglewood Lake) and compliance data from public-supply wells submitted to Ohio Environmental Protection Agency’s 

Safe Drinking Water Information System database (untreated and treated water samples from Burton Village, Chardon City; Christ Presbyterian Church, Lake 

Lucerne Club Co., Middlefield Village; and Tanglewood Lake Water Co.). Locations of public-supply wells are shown in fig. 12; well identifiers and corresponding public-supply well names are listed in table 4. Orange shading indicates the compound is produced as a byproduct of drinking-water chlorination; ●, 

analyzed for but not detected1; ▲, detected in some samples.]

Volatile organic compounds

Domestic 

wells 

(untreated 

water)

Public-supply wells

Untreated water Treated water

USGS

ASM International 

Lake Lucerne

Middlefield Village

Tanglewood Lake

Burton Village

Chardon

Christ Presbyterian

Lake Lucerne

Middlefield Village

Tanglewood Lake

Anthracene ●

Benzo[a]anthracene ●

Benzo[a]pyrene ● ● ●

Benzo[b]fluoranthene ●

Benzo[g,h,i]perylene ●

Benzo[k]fluoranthene ●

bis(2-Chloroethoxy)methane ●

bis(2-Chloroethyl)ether ●

bis(2-Chloroisopropyl)ether ●

bis(2-Ethylhexyl)phthalate 

(DEHP)

●

bis(n-octyl)phthalate ●

Butyl benzyl phthalate ●

Chrysenes, C1-C4 ●

Cymene ●

Di(2-ethylhexyl) adipate ● ●

Di(2-ethylhexyl) pthalate ● ●

Dibenzo[a,h]anthracene ●

Dibutyl phthalate ●

Diethylphthalate ●

Dimethylphthalate ●

Dinitro-o-cresol ●

Flouranthenes, C1-C4 ●

Fluorenes, C1-C3 ●

Hexachlorobenzene ●

Hexachlorocyclopentadiene ●

Ideno[1,2,3-cd]pyrene ●

Isophorone ●
Appendix 4 113

Table 4–3. Volatile organic compounds and semivolatile organic compounds analyzed for in groundwater samples in Geauga County, 

Ohio, 1995–2009.—Continued

[USGS, water samples from 31 domestic wells analyzed by U.S. Geological Survey personnel in 1999 (Jaguck and Darner, 2001); Public-supply well data 

were compiled from Ohio Environmental Protection Agency’s Ambient Ground Water Monitoring Well Network program (untreated water samples from ASM 

International, Middlefield Village, and Tanglewood Lake) and compliance data from public-supply wells submitted to Ohio Environmental Protection Agency’s 

Safe Drinking Water Information System database (untreated and treated water samples from Burton Village, Chardon City; Christ Presbyterian Church, Lake 

Lucerne Club Co., Middlefield Village; and Tanglewood Lake Water Co.). Locations of public-supply wells are shown in fig. 12; well identifiers and corresponding public-supply well names are listed in table 4. Orange shading indicates the compound is produced as a byproduct of drinking-water chlorination; ●, 

analyzed for but not detected1; ▲, detected in some samples.]

Volatile organic compounds

Domestic 

wells 

(untreated 

water)

Public-supply wells

Untreated water Treated water

USGS

ASM International 

Lake Lucerne

Middlefield Village

Tanglewood Lake

Burton Village

Chardon

Christ Presbyterian

Lake Lucerne

Middlefield Village

Tanglewood Lake

4-Nitrophenol ●

n-Nitrosodiphenylamine ●

n-Nitrosodipropylamine ●

nitro-Benzene (Nitrobenzol) ● ● ● ● ● ● ● ●

Pentachlorophenol (PCP) ● ● ●

Phenanthrenes, C1-C4 ●

Phenol (Carbolic acid) ●

Pyrene ●

Polychlorinated biphenyls 

(PCBs)

Arochlor 1016, 1221,1232, 

1242, 1248,1254, & 1260 

●

Total PCBs ● ●

1

 Reporting levels, where known, are as follows (reporting levels for public-supply data changed over time in some cases):

(a) USGS-analyzed domestic wells (1999): benzene, 3 μg/L; trichloroethylene, 5 μg/L, toluene, 3 μg/L, PCE, 5 μg/L, xylene, 13 μg/L (Jagucki and 

Darner, 2001).

(b) Public-supply well data: lab reporting level was generally 0.5 μg/L, with the following exceptions: Dibromoacetic acid, dichloracetic acid, monobromoacetic acid, and trichloroacetic acid, 1 μg/L; Methyl tert-butyl ether (MTBE) , 0.5 μg/L or 2 μg/L (rarely 5 μg/L); Total halocetic acid, maximum reporting level of 6 μg/L; p-xylene, 1.5 μg/L; Total xylenes, 0.05 or 1.5 μg/L; Di(2-ethylhexyl) adipate, 40 μg/L; Di(2-ethylhexyl) pthalate, 0.6 μg/L or 

2 μg/L; Total trihalomethanes (TTHM), 2 μg/L; Benzo[a]pyrene, 0.02 μg/L; Nitro-Benzene, 0.5 μg/L, 5 μg/L, or 10 μg/L; Pentachlorophenol (PCP), 

0.1 μg/L; Total PCBs, 0.1 μg/L.
114 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Appendix 5. Oxidation-Reduction Classification of Samples

Table 5–1. Redox environment classification for domestic wells sampled by U.S. Geological Survey in Geauga County, Ohio, 

1978–2009.—Continued 

[Fe, iron; SO4, sulfate; O2, oxygen; NO3, nitrate; Mn, manganese; O2?, dissolved oxygen was not measured, so the presence of dissolved oxygen in groundwater 

and the process of oxygen reduction cannot be ruled out; Fe(III)-SO4, iron:sulfide ratio indicates that neither iron nor sulfate reduction dominates; Fe(III)/SO4, 

sulfide was not analyzed for, so cannot distinguish between iron and sulfate reduction; Fm., Formation. If more than one redox process is listed, data were insufficient to distinguish between the two processes. The most likely process is listed first. The redox environment classification system is from Jurgens and others, 

2009.]

Well name Year sampled General redox category Redox process Aquifer

GE-18Q1 1980 Oxic or Anoxic O2

? or NO3 Pottsville Fm.

GE-20Q 1980 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4

-O2? Glacial deposits

GE-23 1999 Oxic O2 Pottsville Fm.

GE-34 1978 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4

-O2? Pottsville Fm.

GE-37 1978 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4

-O2? Berea Sandstone

GE-37 1980 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4

-O2? Berea Sandstone

GE-39 1978 Oxic or Anoxic O2

? or NO3 Pottsville Fm.

GE-39 1980 Oxic or Anoxic O2

? or NO3 Pottsville Fm.

GE-39 1986 Oxic or Anoxic O2

? or NO3 Pottsville Fm.

GE-422 1980 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4

-O2? Glacial deposits

GE-44 1978 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4

-O2? Berea Sandstone

GE-44 1980 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4

-O2? Berea Sandstone

GE-44 1986 Suboxic Suboxic Berea Sandstone

GE-48 1978 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4

-O2? Cuyahoga Group

GE-48 1986 Anoxic Fe(III) Cuyahoga Group

GE-49 1978 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4

-O2? Cuyahoga Group

GE-53Q3 1980 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4

-O2? Glacial deposits

GE-55 1978 Oxic or Suboxic O2

? or Suboxic Cuyahoga Group

GE-55 1980 Oxic or Suboxic O2

? or Suboxic Cuyahoga Group

GE-55 1986 Suboxic Suboxic Cuyahoga Group

GE-60 1986 Oxic or Anoxic O2

? or NO3 Pottsville Fm.

GE-61 1980 Oxic or Anoxic O2

? or NO3 Pottsville Fm.

GE-67 1978 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4

-O2? Cuyahoga Group

GE-67 1980 Oxic or Suboxic O2

? or Suboxic Cuyahoga Group

GE-67 1986 Anoxic Fe(III)/SO4 Cuyahoga Group

GE-68 1980 Oxic or Anoxic O2

? or NO3 Pottsville Fm.

GE-68 1986 Anoxic NO3 Pottsville Fm.

GE-69 1986 Anoxic NO3 Pottsville Fm.

GE-73 1978 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4

-O2? Pottsville Fm.

GE-73 1980 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4

-O2? Pottsville Fm.

GE-73 1986 Mixed (anoxic) Fe(III)/SO4

-O2? Pottsville Fm.

GE-77 1986 Anoxic Fe(III)/SO4 Cuyahoga Group

GE-77 1999 Anoxic Fe(III) Cuyahoga Group

GE-77 2009 Mixed (oxic-anoxic) O2

-Fe(III)-SO4 Cuyahoga Group

GE-81Q 1980 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4

-O2? Pottsville Fm.

GE-85 1978 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4

-O2? Glacial deposits

GE-85A 1999 Oxic O2 Pottsville Fm.

GE-85A 2009 Oxic O2 Pottsville Fm.
Appendix 5 115

Table 5–1. Redox environment classification for domestic wells sampled by U.S. Geological Survey in Geauga County, Ohio, 

1978–2009.—Continued 

[Fe, iron; SO4, sulfate; O2, oxygen; NO3, nitrate; Mn, manganese; O2?, dissolved oxygen was not measured, so the presence of dissolved oxygen in groundwater 

and the process of oxygen reduction cannot be ruled out; Fe(III)-SO4, iron:sulfide ratio indicates that neither iron nor sulfate reduction dominates; Fe(III)/SO4, 

sulfide was not analyzed for, so cannot distinguish between iron and sulfate reduction; Fm., Formation. If more than one redox process is listed, data were insufficient to distinguish between the two processes. The most likely process is listed first. The redox environment classification system is from Jurgens and others, 

2009.]

Well name Year sampled General redox category Redox process Aquifer

GE-86 1978 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4-O2? Glacial deposits

GE-86 1980 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4-O2? Glacial deposits

GE-89 1986 Anoxic NO3 Pottsville Fm.

GE-92 1980 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4-O2? Pottsville Fm.

GE-92 1986 Anoxic Fe(III)/SO4 Pottsville Fm.

GE-95 1980 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4-O2? Pottsville Fm.

GE-101 1986 Mixed (anoxic) Fe(III)-SO4 Glacial deposits

GE-101 1999 Mixed (anoxic) Fe(III)-SO4 Glacial deposits

GE-102 1986 Oxic O2 Berea Sandstone

GE-103 1980 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4-O2? Berea Sandstone

GE-103 1986 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4-O2? Berea Sandstone

GE-103 1999 Anoxic Fe(III) Berea Sandstone

GE-103 2009 Anoxic Fe(III) Berea Sandstone

GE-104 1986 Anoxic Fe(III)/SO4 Berea Sandstone

GE-104 1999 Mixed (anoxic) Fe(III)-SO4 Berea Sandstone

GE-105 1980 Oxic or Suboxic O2? or Suboxic Cuyahoga Group

GE-105 1986 Mixed (anoxic) Fe(III)-SO4 Cuyahoga Group

GE-108 1980 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4-O2? Glacial deposits

GE-108 1986 Suboxic Suboxic Glacial deposits

GE-108 1999 Mixed (anoxic) Fe(III)-SO4 Glacial deposits

GE-108 2009 Mixed (anoxic) Fe(III)-SO4 Glacial deposits

GE-109 1986 Anoxic Fe(III)/SO4 Pottsville Fm.

GE-109 1999 Mixed (anoxic) Fe(III)-SO4 Pottsville Fm.

GE-109 2009 Mixed (oxic-anoxic) O2-Fe(III)-SO4 Pottsville Fm.

GE-111 1986 Anoxic NO3 Pottsville Fm.

GE-112 1980 Mixed (anoxic) or (oxic-anoxic) Fe(III)/SO4-O2? or NO3 Pottsville Fm.

GE-112 1986 Anoxic NO3 Pottsville Fm.

GE-115 1986 Anoxic Fe(III)/SO4 Pottsville Fm.

GE-116 1980 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4-O2? Glacial deposits

GE-116 1986 Anoxic Fe(III)/SO4 Glacial deposits

GE-119 1980 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4-O2? Pottsville Fm.

GE-120 1986 Suboxic Suboxic Berea Sandstone

GE-120 1999 Suboxic Suboxic Berea Sandstone

GE-120 2009 Oxic O2 Berea Sandstone

GE-122 1986 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4-O2? Berea Sandstone

GE-122 1999 Anoxic Fe(III) Berea Sandstone

GE-126 1986 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4-O2? Berea Sandstone

GE-126 1999 Mixed (anoxic) Fe(III)-SO4 Berea Sandstone

GE-126 2009 Mixed (oxic-anoxic) O2-Fe(III)-SO4 Berea Sandstone
116 Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009

Table 5–1. Redox environment classification for domestic wells sampled by U.S. Geological Survey in Geauga County, Ohio, 

1978–2009.—Continued 

[Fe, iron; SO4, sulfate; O2, oxygen; NO3, nitrate; Mn, manganese; O2?, dissolved oxygen was not measured, so the presence of dissolved oxygen in groundwater 

and the process of oxygen reduction cannot be ruled out; Fe(III)-SO4, iron:sulfide ratio indicates that neither iron nor sulfate reduction dominates; Fe(III)/SO4, 

sulfide was not analyzed for, so cannot distinguish between iron and sulfate reduction; Fm., Formation. If more than one redox process is listed, data were insufficient to distinguish between the two processes. The most likely process is listed first. The redox environment classification system is from Jurgens and others, 

2009.]

Well name Year sampled General redox category Redox process Aquifer

GE-141 1986 Anoxic Fe(III)/SO4 Glacial deposits

GE-141 1999 Anoxic Fe(III) Glacial deposits

GE-141 2009 Mixed (oxic-anoxic) O2-Fe(III) Glacial deposits

GE-147 1986 Anoxic Fe(III)/SO4 Cuyahoga Group

GE-147 1999 Mixed (anoxic) Fe(III)-SO4 Cuyahoga Group

GE-147 2009 Mixed (oxic-anoxic) O2-Fe(III)-SO4 Cuyahoga Group

GE-151 1986 Anoxic or Mixed (oxic-anoxic) Fe(III)/SO4-O2? Pottsville Fm.

GE-151 1999 Mixed (anoxic) Fe(III)-SO4 Pottsville Fm.

GE-151 2009 Mixed (oxic-anoxic) O2-Fe(III)-SO4 Pottsville Fm.

GE-157 1999 Mixed (anoxic) Fe(III)-SO4 Glacial deposits

GE-159 1986 Suboxic Suboxic Berea Sandstone

GE-159 1999 Oxic O2 Berea Sandstone

GE-165 1986 Anoxic Fe(III)/SO4 Glacial deposits

GE-165 1999 Anoxic Fe(III) Glacial deposits

GE-165 2009 Mixed (oxic-anoxic) O2-Fe(III) Glacial deposits

GE-169 1986 Anoxic Fe(III)/SO4 Cuyahoga Group

GE-174 1986 Anoxic Fe(III)/SO4 Glacial deposits

GE-174A 1999 Anoxic Mn(IV) Glacial deposits

GE-175 1986 Anoxic Fe(III)/SO4 Glacial deposits

GE-180 1986 Anoxic NO3 Pottsville Fm.

GE-185A 1999 Anoxic Fe(III) Cuyahoga Group

GE-185A 2009 Anoxic Fe(III) Cuyahoga Group

GE-186 1986 Suboxic Suboxic Cuyahoga Group

GE-202 1986 Anoxic Fe(III) Pottsville Fm.

GE-202 1999 Anoxic Fe(III) Pottsville Fm.

GE-202 2009 Anoxic Fe(III) Pottsville Fm.

GE-204 1999 Mixed (anoxic) Fe(III)-SO4 Pottsville Fm.

GE-228 1999 Mixed (anoxic) Fe(III)-SO4 Cuyahoga Group

GE-234 1999 Anoxic Fe(III) Cuyahoga Group

GE-234 2009 Mixed (oxic-anoxic) O2-Fe(III)-SO4 Cuyahoga Group

GE-235 1999 Anoxic Fe(III) Glacial deposits

GE-280 1999 Mixed (oxic-anoxic) O2-Fe(III) Cuyahoga Group

GE-321 1999 Mixed (anoxic) Fe(III)-SO4 Glacial deposits

GE-332 1999 Oxic O2 Pottsville Fm.

GE-332 2009 Oxic O2 Pottsville Fm.

GE-341 1999 Mixed (oxic-anoxic) O2-Mn(IV) Cuyahoga Group

GE-341 2009 Mixed (oxic-anoxic) O2-Mn(IV) Cuyahoga Group

GE-349A 1999 Oxic O2 Pottsville Fm.

GE-355 1999 Oxic O2 Pottsville Fm.

1

GE-18Q was a Chagrin Falls public-supply well. 

2

GE-42 was a Middlefield Village public-supply well.

3

GE-53Q was a City of Chardon public-supply well.

Jagucki and others—Groundwater Quality in Geauga County, Ohio—Status, 2009, and Changes During 1978–2009—Scientific Investigations Report 2015–5032

ISSN 2328-031X (print)

ISSN 2328-0328 (online)

http://dx.doi.org/10.3133/sir20155032