U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2009–5093

Prepared in cooperation with the Kansas Water Office

Quality Characteristics of Ground Water in the Ozark 

Aquifer of Northwestern Arkansas, Southeastern Kansas, 

Southwestern Missouri, and Northeastern Oklahoma, 

2006–07
Cover photograph. Geophysical logging of well near Pittsburg, Kansas, August 2007 (Photograph taken by L.M. Pope, USGS).
Quality Characteristics of Ground Water 

in the Ozark Aquifer of Northwestern 

Arkansas, Southeastern Kansas, 

Southwestern Missouri, and Northeastern 

Oklahoma, 2006–07

By L. M. Pope, H.E. Mehl, and R.L. Coiner

Prepared in cooperation with the Kansas Water Office

Scientific Investigations Report 2009–5093

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2009

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

To order this and other USGS information products, visit http://store.usgs.gov

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

U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Pope, L.M., Mehl, H.E., and Coiner, R.L., 2009, Quality characteristics of ground water in the Ozark aquifer of northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07: U.S. Geological Survey Scientific Investigations Report 2009–5093, 60 p.
iii

Contents

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

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

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

Previous Investigations........................................................................................................................2

Description of Study Area ............................................................................................................................5

Climate....................................................................................................................................................5

Physiography.........................................................................................................................................6

Geology...................................................................................................................................................6

Geohydrology.........................................................................................................................................8

Methods of Investigation............................................................................................................................10

Well Selection and Sample Collection............................................................................................10

Sample Analysis..................................................................................................................................14

Geophysical Logging, Well-Bore Flow, and Depth-Dependent Sampling.................................14

Unstable Isotope Analysis.................................................................................................................15

Quality Assurance...............................................................................................................................15

Quality Characteristics of Ground Water.................................................................................................20

Spatial Distribution .............................................................................................................................20

Physical Properties ...................................................................................................................21

Dissolved Solids and Major Ions.............................................................................................22

Nutrients......................................................................................................................................26

Trace Elements...........................................................................................................................30

Potential Effect of Mining on Water Quality............................................................................................30

Summary of Regulatory Exceedances ............................................................................................34

Flow-Path Evolution............................................................................................................................34

Vertical Variability...............................................................................................................................39

Summary........................................................................................................................................................42

Acknowledgments..............................................................................................................................44

References Cited..........................................................................................................................................44

Supplemental Information..........................................................................................................................49

Figures

1. Map showing location of Ozark Plateaus aquifer system, surficial extent of geohydrologic units, physiographic areas, and water-quality study area of the Ozark aquifer in 

parts of Arkansas, Kansas, Missouri, and Oklahoma.............................................................3

2. Graphs showing average monthly mean temperature and precipitation at Chanute, 

Kansas, and Fayetteville, Arkansas, for 1971–2000.................................................................5

3. Generalized geohydrologic section showing Ozark Plateaus aquifer system and adjacent hydrologic units....................................................................................................................7

4. Map showing location of 40 water-supply wells sampled as part of an assessment of 

ground-water quality in Ozark aquifer, northwestern Arkansas, southeastern Kansas, 

southwestern Missouri, and northeastern Oklahoma, 2006–07..........................................13
iv

5. Graph showing method reporting limits, sample concentrations and median values, 

and drinking-water standards for dissolved solids and major ions detected in ground 

water from 40 water-supply wells completed in Ozark aquifer, northwestern Arkansas, 

southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 

2006–07 .........................................................................................................................................23

6. Map showing distribution of dissolved-solids concentrations in ground water from 

40 water-supply wells completed in Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07 ...................24

7. Graph showing major ion composition of ground water from 40 water-supply wells 

completed in Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07 ............................................................25

8. Graph showing relation between summation of major ions and dissolved solids in 

ground water from 40 water-supply wells completed in Ozark aquifer, northwestern 

Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 

2006–07 .........................................................................................................................................26

9. Map showing distribution of chloride concentrations in ground water from 40 watersupply wells completed in Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07 .................................27

10. Map showing distribution of sulfate concentrations in ground water from 40 watersupply wells completed in Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07 .................................28

11. Graph showing method reporting limits, sample concentrations and median values, 

and drinking-water standards for nutrients detected in ground water from 40 watersupply wells completed in Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07 .................................29

12. Graph showing method reporting limits, sample concentrations and median values, 

and drinking-water standards for trace elements detected in ground water from 

40 water-supply wells completed in Ozark aquifer, northeastern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07 ...................31

13. Map showing potentiometric surface of Ozark aquifer, spring 2006, and water-supply 

wells completed in Ozark aquifer delineating two ground-water flow paths, and stiff 

diagrams showing results of water-quality analyses, fall 2006, and identification of 

watertypes ...................................................................................................................................35

14–19. Graphs showing:

14. Relation between δ18O and δ2H stable isotopes in ground water from 11 flow-path 

wells completed in Ozark aquifer of southeastern Kansas and southwestern Missouri, 

2006 ...............................................................................................................................................36

15. Relation of sampling-site latitudes and δ18O isotope values from 391 river-water 

sampling sites in eastern United States (Kendall and Coplen, 2001) to average latitudes 

and δ18O isotope values in ground water from 11 flow-path wells completed in Ozark 

aquifer of southeastern Kansas and southwestern Missouri, 2006...................................36

16. Carbon-14 (14C) activity in ground water from 11 flow-path wells completed in Ozark 

aquifer of southeastern Kansas and southwestern Missouri, 2006...................................37

17. Strontium (Sr) concentrations and 87Sr/86Sr isotope ratios in ground water from 

11 flow-path wells completed in Ozark aquifer of southeastern Kansas and southwestern Missouri, 2006.......................................................................................................................38

18. Dissolved-solids, sulfate, and chloride concentrations in ground water from 11 flowpath wells completed in Ozark aquifer of southeastern Kansas and southwestern 

Missouri, 2006..............................................................................................................................39
v

19. Selected results of geophysical logging, well-bore flow accretion, and depthdependent water-quality sampling at Pittsburg, Kansas, city well 10, June–August 

2007, showing vertical variability in ground-water flow and water quality ......................41

Tables

1. Geologic and geohydrologic units in Ozark Plateaus aquifer system and adjacent 

areas, in northwestern Arkansas, southeastern Kansas, southwestern Missouri, and 

northeastern Oklahoma ...............................................................................................................9

2. Equipment used for onsite measurements of physical properties of ground water and 

borehole geophysics..................................................................................................................11

3. Selected well information for sampled water-supply wells completed in Ozark aquifer, 

northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07 ..............................................................................................................12

4. Laboratory analysis methods for measured water-quality constituents ..........................14

5. Statistical summary of absolute relative percentage differences (RPDs) between 

selected water-quality constituents in concurrently collected replicate samples of 

ground water from water-supply wells completed in Ozark aquifer, northwestern 

Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 

2006–07 .........................................................................................................................................17

6. Results of analyses of source water used to decontaminate sampling equipment 

between sample collections and equipment-blank samples processed with source 

water, 2006–07.............................................................................................................................19

7. Statistical summary and U.S. Environmental Protection Agency (2006) drinkingwater standards for physical properties measured or analyzed in ground water from 

40 water-supply wells completed in Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07 ...................21

8. Statistical summary and U.S. Environmental Protection Agency (2006) drinking-water 

standards for dissolved solids and major ions in ground water from 40 water-supply 

wells completed in Ozark aquifer, northwestern Arkansas, southeastern Kansas, 

southwestern Missouri, and northeastern Oklahoma, 2006–07..........................................22

9. Statistical summary and U.S. Environmental Protection Agency (2006) drinking-water 

standards for nutrients in ground water from 40 water-supply wells completed in Ozark 

aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, and 

northeastern Oklahoma, 2006–07.............................................................................................29

10. Statistical summary and U.S. Environmental Protection Agency (2006) drinking-water 

standards for trace elements in ground water from 40 water-supply wells completed in 

Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, 

and northeastern Oklahoma, 2006–07 .....................................................................................32

11. Physical property and chemical-constituent determinations that exceed U.S. Environmental Protection Agency (2006) drinking-water standards in ground water from 40 

water-supply wells completed in Ozark aquifer, northwestern Arkansas, southeastern 

Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07 ..........................33

12. Concentrations of dissolved solids and selected major ions and overall percentage 

change along westerly and northwesterly ground-water flow paths in Ozark aquifer of 

southeastern Kansas and southwestern Missouri, 2006 .....................................................40

13. Water-quality properties or constituents analyzed in ground water from 40 water-supply wells completed in Ozark aquifer, northwestern Arkansas, southeastern Kansas, 

southwestern Missouri, and northeastern Oklahoma, 2006–07..........................................50
vi

14. Results of measurements or analysis of physical properties in ground water from 

40 water-supply wells completed in Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07 ...................51

15. Results of dissolved solids and major ion analyses of ground water from 40 water-supply wells completed in Ozark aquifer, northwestern Arkansas, southeastern Kansas, 

southwestern Missouri, and northeastern Oklahoma, 2006–07..........................................52

16. Results of nutrient analyses of ground water from 40 water-supply wells completed in 

Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, 

and northeastern Oklahoma, 2006–07 .....................................................................................54

17. Results of selected trace element and stable isotope analyses of ground water from 

40 water-supply wells completed in Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07 ...................55

18. Results of measurements or analysis of physical properties and chemical analyses 

of depth-dependent ground-water samples collected under pumping conditions from 

Pittsburg, Kansas, city well 10, August 13–14, 2007..............................................................59

Conversion Factors, Abbreviations, and Datum

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

inch (in.) 25,440 micrometer (mm)

Volume

acre-foot (acre-ft) 1,230 cubic meter (m3) 

Flow rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

million gallons per day (Mgal/d) 0.0438 cubic meter per second (m3/s)

gallon per minute (gal/min) 6.31 x 10-5 cubic meter per second (m3/s)

Mass

gram (g) 0.03527 milligrams per day (g/d)

Chemical Constituents

microgram per liter (μg/L) 1.0 part per billion (ppb)

milligram per liter (mg/L) 1.0 part per million (ppm) 

picocuries per liter (pCi/L) 3.7854 picocuries per liter (pCi/L)

microsiemens per inch at 25 degrees 

Celsius (μS/cm)

2.54 microsiemens per centimeter at 25 degrees 

Celsius (μS/cm)

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 referenced to the “North American Vertical Datum of 1929 

(NAVD 29).”

Horizontal coordinate information is referenced to the “North American Datum of 1983 (NAD 

83).”

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

Acronymns and Other Abbreviations Used in This Report

o

/oo per thousand parts (permil)

AL Action Level (U.S. Environmental Protection Agency)

API American Petroleum Institute

bls below land surface

BP before present 14C carbon-14

CaCO3 calcium carbonate

CDT Canon Diablo Triolite

CO3

2- carbonate

DIC dissolved inorganic carbon

DOC dissolved organic carbon

E estimated

Eh redox potential

GMWL Global Meteoric Water Line 3

H hydrogen-3

HAL health advisory level (U.S. Environmental Protection Agency)

HCO3 bicarbonate

ICPMS inductively coupled mass spectrometry

LR lateral resistivity

M presence verified but not quantified

MCL Maximum Contaminant Level (U.S. Environmental Protection Agency)

MCLG Maximum Contaminant Level Goal (U.S. Environmental Protection Agency)

MRL method reporting limit

N/A not applicable

NAD 83 North American Datum of 1983

NAVD 88 North American Vertical Datum of 1988

NAWQA National Water-Quality Assessment (U.S. Geological Survey)

NTU nephelometric turbidity unit

NWQL National Water Quality Laboratory (U.S. Geological Survey)

O oxygen

ORP oxidation-reduction potential

pmC percentage of modern carbon

PVC polyvinyl chloride

RPD relative percentage difference

S sulfur

SDWR Secondary Drinking-Water Regulation (U.S. Environmental Protection 

Agency)

SHE relative to standard hydrogen electrode

Sr strontium 86Sr/88Sr ratio of strontium-86 to strontium-88 (isotopes)

USEPA U.S. Environmental Protection Agency)

USGS U.S. Geological Survey

VPDB Vienna Pee Dee Belemite

VSMOW Vienna Standard Mean Ocean Water

Abstract

Because of water quantity and quality concerns within 

the Ozark aquifer, the State of Kansas in 2004 issued a 

moratorium on most new appropriations from the aquifer until 

results were made available from a cooperative study between 

the U.S. Geological Survey and the Kansas Water Office. The 

purposes of the study were to develop a regional ground-water 

flow model and a water-quality assessment of the Ozark aquifer in northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma (study area). 

In 2006 and 2007, water-quality samples were collected from 

40 water-supply wells completed in the Ozark aquifer and 

spatially distributed throughout the study area. Samples were 

analyzed for physical properties, dissolved solids and major 

ions, nutrients, trace elements, and selected isotopes. This 

report presents the results of the water-quality assessment part 

of the cooperative study.

Water-quality characteristics were evaluated relative 

to U.S. Environmental Protection Agency drinking-water 

standards. Secondary Drinking-Water Regulations were 

exceeded for dissolved solids (11 wells), sulfate and chloride 

(2 wells each), fluoride (3 wells), iron (4 wells), and manganese (2 wells). Maximum Contaminant Levels were exceeded 

for turbidity (3 wells) and fluoride (1 well). The Maximum 

Contaminant Level Goal for lead (0 milligrams per liter) was 

exceeded in water from 12 wells.

Analyses of isotopes in water from wells along two 

60-mile long ground-water flow paths indicated that water in 

the Ozark aquifer was at least 60 years old but the upper age 

limit is uncertain. The source of recharge water for the wells 

along the flow paths appeared to be of meteoric origin because 

of isotopic similarity to the established Global Meteoric Water 

Line and a global precipitation relation. Additionally, analysis 

of hydrogen-3 (3H) and carbon-14 (14C) indicated that there 

was possible leakage of younger ground water into the lower 

part of the Ozark aquifer. This may be caused by cracks or fissures in the confining unit that separates the upper and lower 

parts of the aquifer, poorly constructed or abandoned wells, or 

historic mining activities.

 Analyses of major ions in water from wells along the 

flow paths indicated a transition from freshwater in the east to 

saline water in the west. Generally, ground water along flow 

paths evolved from a calcium magnesium bicarbonate type 

to a sodium calcium bicarbonate or a sodium calcium chloride bicarbonate type as water moved from recharge areas in 

Missouri into Kansas. Much of this evolution occurred within 

the last 20 to 25 miles of the flow paths along a water-quality 

transition zone near the Kansas-Missouri State line and west. 

The water quality of the Kansas part of the Ozark aquifer is 

degraded compared to the Missouri part.

Geophysical and well-bore flow information and depthdependent water-quality samples were collected from a 

large-capacity (1,900–2,300 gallons per minute) municipalsupply well to evaluate vertical ground-water flow accretion 

and variability in water-quality characteristics at different 

levels. Although the 1,050-foot deep supply well had 500 feet 

of borehole open to the Ozark aquifer, 77 percent of groundwater flow entering the borehole came from two 20-foot thick 

rock layers above the 1,000-foot level. For the most part, 

water-quality characteristics changed little from the deepest sample to the well-head sample, and upwelling of saline 

water from deeper geologic formations below the well was not 

evident. However, more saline water may be present below the 

bottom of the well.

Introduction

The Ozark aquifer is part of the Ozark Plateaus aquifer 

system that occurs in parts of Arkansas, Kansas, Missouri, and 

Oklahoma (fig. 1). The Ozark aquifer is a source of freshwater 

for municipal, domestic, industrial, and irrigation uses, and as 

such, an interstate concern exists for the long-term sustainability of the resource and protection of the aquifer from waterquality degradation. Since pumping from the aquifer began in 

the 1880s, substantial ground-water-level declines have been 

Quality Characteristics of Ground Water in the Ozark 

Aquifer of Northwestern Arkansas, Southeastern Kansas, 

Southwestern Missouri, and Northeastern Oklahoma, 

2006–07

By L. M. Pope, H.E. Mehl, and R.L. Coiner
2 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

noted in some areas. Stramel (1957) identified a static waterlevel decline of more than 100 ft between 1882 and 1954 in 

the Pittsburg, Kansas area, and Reed and others (1955) documented a water-level decline of more than 400 ft near Miami, 

Oklahoma, from 1900 to 1950.

Water quality in supply wells completed in the Ozark 

aquifer potentially could be degraded with increased water 

demand from a growing population. Increases in pumping 

rates at major population centers near the Kansas-Missouri 

State line or in northeastern Oklahoma may further lower 

water levels in the Ozark aquifer such that, locally, the natural 

east-to-west flow gradient (Imes and Emmett, 1994) decreases 

and saline water from the western part of the aquifer (Macfarlane and Hathaway, 1987) migrates to the east. Recently, 

cones of depressed ground-water levels were identified around 

major pumping centers (Gillip and others, 2008). Additionally, upwelling of saline water from lower geologic strata may 

be possible especially at the pumping centers. Lower water 

levels in the Ozark aquifer may increase the hydraulic gradient 

between the overlying aquifer system (Springfield Plateau 

aquifer) and the Ozark aquifer (fig. 1). This increased gradient may draw highly mineralized or contaminated water in the 

Springfield Plateau aquifer through areas where the intervening confining unit is more permeable or through older or 

abandoned wells or mining-related exploratory drill holes that 

are open to both the Springfield Plateau and Ozark aquifers. 

Commercial lead-and-zinc mining in the Mississippian-age 

rock formations of the Springfield Plateau aquifer occurred 

from about 1870 to 1970 in the area of southeastern Kansas, 

southwestern Missouri, and northeastern Oklahoma known 

as the Tri-State Mining District (Gibson, 1972). The legacy 

of this long mining history includes trace element (cadmium, 

lead, and zinc) contamination of large areas of the Springfield Plateau aquifer (Barks, 1977; Playton and others, 1980; 

Spruill, 1987) and surface-water sources (Bailey, 1911; Pope, 

2005; Juracek, 2006; Angelo and others, 2007).

Because of water quantity and quality concerns within the 

Ozark aquifer, the State of Kansas in 2004 issued a moratorium on new appropriations from the Ozark aquifer in Kansas 

with the exclusion of domestic supplies, requests for less than 

5 acre-ft of water per year, and temporary and term permits 

(Kansas Administrative Regulation 5–3–29). This moratorium is to remain in force until a regional ground-water flow 

model of the Ozark aquifer in parts of northwestern Arkansas, 

southeastern Kansas, southwestern Missouri, and northeastern 

Oklahoma (hereinafter referred to as the study area; fig. 1) 

is developed to simulate the effects of existing and proposed 

municipal and industrial ground-water withdrawal rates on 

ground-water levels. This model will extend sufficiently 

to include the major pumping centers in Joplin, Missouri, 

Pittsburg, Kansas, and Miami, Oklahoma. The model will be 

useful in determining recharge areas of selected wells and well 

fields and will help water managers better understand how 

surface contamination can potentially affect water quality in 

supply wells.

In 2005, the U.S. Geological Survey (USGS) entered 

into a cooperative agreement with the Kansas Water Office 

to develop a regional ground-water flow model of the study 

area to include the Ozark and Springfield Plateau aquifers, to 

construct potentiometric-surface maps of both aquifers, and 

to conduct an assessment of current water-quality conditions 

within the Ozark aquifer. The ground-water flow model will be 

developed using the USGS MODFLOW-2000 (Hill and others, 2000) ground-water flow simulator. During the spring of 

2006, ground-water levels were measured at 285 wells in the 

Ozark and Springfield Plateau aquifers throughout the study 

area. Results of these measurements were used to construct the 

potentiometric surface maps that are presented in Gillip and 

others (2008). Information generated by the combined groundwater flow model development and water-quality assessment 

will provide water managers the ability to better assess the 

availability of ground water in their area, to better determine 

the effects of pumping on ground-water levels, and to better 

assess the potential for possible future contamination of wells. 

Purpose and Scope

The purpose of this report is to provide an assessment 

of quality characteristics of water in the Ozark aquifer in 

northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma. This assessment 

contains the results of chemical analyses of water from 

40 spatially distributed water-supply wells completed in 

the Ozark aquifer. These results are used to identify spatial 

variability in aquifer water quality throughout the study area 

and water quality evolution along two selected ground-water 

flow paths. Vertical variability in water quality in the Ozark 

aquifer also is assessed on the basis of a series of samples collected in the vertical profile of a municipal-supply well under 

pumping conditions.

 The scope of this report is limited to an assessment of 

selected major ions, nutrients, trace elements, and selected 

isotopes in ground water from wells in the Ozark aquifer in the 

study area. Many of these water-quality constituents are regulated in drinking-water supplies by the U.S. Environmental 

Protection Agency (USEPA). The constituents are discussed 

relative to USEPA drinking-water standards as a frame of 

reference and to other natural geohydrologic factors that may 

affect variability in constituent concentrations.

Previous Investigations

Previous investigations in the Ozark Plateaus aquifer system and surrounding areas have produced many publications 

describing various aspects of all or part of the aquifer system. 

Stratigraphic succession of the area, including the aquifer system, has been presented by Koenig (1961) and Zeller (1968), 

and more locally or regionally specific geologic aspects 

were discussed by Snider (1915), Keroher and Kirby (1948), 

McCracken (1964, 1967, 1971), Bretz (1965), Denison (1981), 
Introduction 3

0

0 25 50 75 100 MILES

25 50 75 100 KILOMETERS

95° 30' 94° 30' 93° 30' 92° 30'

38°30'

30' 91° 30' 90°

35°30'

30'

30'

38°

37°

36°

Base from U.S. Geological Survey digital data, 1999, 1:100,000

Universal Transverse Mercator projection

Zone 15

Horizontal coordinate information is referenced to the North American

 Datum of 1983 (NAD 83)

Physiography modified from Adamski, 1997

EXPLANATION

Geohydrologic unit

Mississippi River Valley

alluvial aquifer

Western Interior Plains

 confining unit and 

 aquifer

Springfield Plateau

aquifer

Ozark confining unit

and aquifer

St. Francois confining

unit and aquifer

Study area

KANSAS

KANSAS

OKLAHOMA

OKLAHOMA

ARKANSAS

ARKANSAS

MISSOURI

MISSOURI

MISSOURI

ILLINOIS

Boston Mountains 

Arkansas Valley

Springfield

Plateau

Osage

Plains

Salem Plateau

St. Francois

Mountains

Mississippi Alluvial Plain

O Z A R K P L A T E A U S

C O A S T A L

P L A I N

C E N T R A L

L O W L A N D

O U A C H I T A

Boundary of Ozark Plateaus

 aquifer system

Boundary of physiographic

 province

Boundary of physiographic

 section

Boundary of study area

Jasper

County

Barry

County

Washington

County

Fayetteville

Joplin

Pittsburg

Chanute

Miami

Springfiled

Ottawa

County

MISSOURI

KANSAS

OKLAHOMA

ARKANSAS

Index map

96°

Tri-State Mining

District

Figure 1. Location of Ozark Plateaus aquifer system, surficial extent of geohydrologic units, physiographic areas, and water-quality 

study area of the Ozark aquifer in parts of Arkansas, Kansas, Missouri, and Oklahoma.
4 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

and Thompson (1991). The geohydrology of the area was 

discussed by Abernathy (1941), Stramel (1957), Emmett and 

others (1979), Macfarlane and others (1981), and Kleeschulte 

and others (1985). Ground-water-quality characteristics have 

been investigated for at least the past 60 years as typified in 

publications by Williams (1948), Feder and others (1969), 

Barks (1978), Feder (1979), Macfarlane and others (1981), 

Christenson and others (1990), and Imes and Davis (1991). 

Because of the occurrence of the historic Tri-State Mining 

District within the Ozark Plateaus aquifer system (specifically 

the Springfield Plateau aquifer, fig. 1), ground-water-quality 

effects of this past mining activity have been investigated by 

Barks (1977), Parkhurst (1987), and Spruill (1987), to name a 

few. More specific, however, to water-quality characteristics in 

the Ozark aquifer and more directly relevant to the investigation described in this report are the investigations conducted 

by Darr (1978), Macfarlane and Hathaway (1987), Jorgensen 

(1989), Imes and Emmett (1994), Adamski and others (1995), 

Jorgensen and others (1996), and Gillip and others (2008). 

Darr (1978) conducted the first detailed investigation into 

the hydrogeochemistry of the Ozark Plateaus aquifer system. 

His work led to better understanding of rock-water interactions, the effect of biota on production of hydrogen sulfide, 

and the hydrogeochemical evolution of ground water. Macfarlane and Hathaway (1987) described the hydrogeology and 

chemical quality of ground water in Cambrian and Ordovician 

strata of the lower Paleozoic aquifers in the Tri-State area 

of southeastern Kansas, southwestern Missouri, and northeastern Oklahoma. Ground water was available throughout 

these layers in varying amounts depending on lithologies and 

secondary permeability. Movement of ground water in the 

aquifers was affected locally by pumping centers, which have 

produced large cones of depression in several areas. Groundwater quality reflected a transition from fresh-to-saline 

conditions starting at about the Kansas-Missouri State line. 

The freshwater part of the aquifer in Missouri generally was 

a calcium bicarbonate type transitioning to a sodium chloride 

type in the saline part in Kansas. Concentrations of dissolved 

solids and chloride were found to increase in a generally 

westerly direction. 

Jorgensen (1989) presented a detailed description of 

the paleohydrology of the central United States that emphasized the geology of ground water and how the properties of 

aquifers can be evaluated or estimated from paleohydrologic 

analysis and concluded that diagenesis resulting from past 

conditions generally has determined the hydraulic characteristics of present-day aquifers. Also presented was a detailed 

examination of the geologic processes affecting the central 

United States from the Precambrian through present day. 

The area was alternately submerged and exposed by marine 

transgressions and regressions that deposited sand, calcareous mud, or clay sediment, depending on the time period, that 

were subsequently lithified over time into distinct layers of 

sandstone, limestone, and shale that compose the modern-day 

aquifers and confining units.

Imes and Emmett (1994) discussed the geohydrology of 

the Ozark Plateaus aquifer system in parts of Kansas, Missouri, and Oklahoma, identified seven geohydrologic units 

composing the aquifer system, and presented details on the 

permeability, rock composition, thickness, water levels, and 

well yields of each unit. Maps presented depicted the areal 

extent, thickness, and upper surface of each aquifer or geohydrologic unit and the predevelopment potentiometric surface 

of the aquifers. Maps also showed water type and concentrations of dissolved solids, sulfate, and chloride in ground water 

from each aquifer on the basis of available chemical analyses. 

Dissolved-solids concentrations in the aquifers ranged from 

about 200 mg/L (milligrams per liter) where the aquifers 

crop out to more than 2,000 mg/ L near the western boundary of the aquifers. The authors used a three-dimensional 

finite-difference model to simulate regional ground-water 

flow in the Ozark Plateaus aquifer system under predevelopment conditions and concluded that, because the present-day 

(1994) pumping rates were small compared to the large rates 

of recharge, the regional predevelopment ground-water budget 

was probably similar to the present-day budget. Although 

there was no apparent regional lowering of water levels in 

the aquifer system, decreased hydraulic heads existed around 

major pumping centers in Pittsburg, Kansas, Springfield, Missouri, and Miami, Oklahoma. 

Adamski and others (1995) described the environmental and hydrologic setting of the Ozark Plateaus study unit 

of the USGS National Water-Quality Assessment Program 

(NAWQA) and how related geologic and land-use characteristics may affect water quality. The authors reviewed rock 

composition, permeability, and well yield of each geohydrologic unit and noted that karst features such as springs, 

sinkholes, and caves are common in the study unit. Population 

in the study unit increased 28 percent between 1970 and 1990, 

to about 2.3 million people (Adamski and others, 1995). Land 

use was predominantly pasture and cropland in the northwest, 

and forest and pasture in the southeast, with poultry farms 

commonly found in the southwestern part of the study unit 

(Adamski and others, 1995). Lead-zinc mining was common 

in the past. Total water use for the area during the NAWQA 

study averaged 1,053 Mgal/d, with ground water accounting 

for about 58 percent and surface water providing 42 percent. 

Ground water was described as mostly a calcium or calcium 

magnesium bicarbonate type with some local wells in confined parts of the aquifers yielding water of calcium sulfate or 

sodium chloride composition. Dissolved-solids concentrations 

in ground water ranged from 200 to 300 mg/L but were as 

much as 10,000 mg/L in the deeper aquifers along the western 

boundary. The geochemical processes of mineral dissolution, ion exchange, and oxidation-reduction reactions were 

the dominant natural factors that affected water quality on a 

regional scale.

Jorgensen and others (1996) provided a summary of the 

geochemistry of regional aquifers in the study area. Ground 

water in the Ozark Plateaus generally flows westward toward 

a broad physiographic low roughly paralleling the Central 
Description of Study Area 5

Lowland Province (fig. 1). The Western Interior Plains aquifer 

system (fig. 1) extends westward into Kansas and Oklahoma 

and ground-water flow is generally toward the east. The 

authors reviewed the hydrogeologic features of the Ozark 

Plateaus aquifer system units in detail, and referred to Imes 

and Emmet’s (1994) simulation of ground-water flow. The 

study by Jorgensen and others (1996) was mainly a review 

and summary of the large quantities of hydrologic, geologic, 

and water-quality data pertaining to this area that have been 

collected over many years. The authors reviewed the data for 

accuracy and generated various computer models of aquifer 

properties and hydrologic information. Of particular interest 

for the study described in this report is their finding that the 

Ozark aquifer and St. Francois aquifer are similar in hydrochemistry due to the relatively large permeability of the St. 

Francois confining unit. Water in these aquifers generally contained less than 500 mg/L dissolved solids and was a calcium 

magnesium bicarbonate type. Jorgensen and others (1996) 

also noted that ground water in the Springfield Plateau aquifer 

contained dissolved-solids concentrations generally less than 

300 mg/L and was a calcium bicarbonate type. 

Gillip and others (2008) used ground-water levels from 

285 wells measured during the spring of 2006 to develop 

potentiometric-surface maps for the Springfield Plateau and 

Ozark aquifers to address the effects of changing water use 

over time. The potentiometric-surface map of the Springfield 

Plateau aquifer showed a maximum measured water-level 

altitude of about 1,450 ft in Barry County, Missouri, and a 

minimum altitude of 579 ft in Ottawa County, Oklahoma. 

Ground water in this aquifer generally flows to the west, and 

discharges to regional lakes, rivers, and springs. The potentiometric-surface map of the Ozark aquifer showed a maximum water-level altitude of 1,303 ft in Washington County, 

Arkansas, and a minimum water-level altitude of 390 ft in 

Ottawa County, Oklahoma. The ground-water flow in the 

Ozark aquifer was generally to the west or northwest. Cones 

of depression around public water-supply wells were present in several counties of Kansas, Missouri, and Oklahoma. 

The potentiometric-surface map showed the largest cones of 

depression in Ottawa County, Oklahoma (from about 700 to 

390 ft), Jasper County, Missouri (from about 800 to 577 ft), 

and Barry County, Missouri (from about 1,100 to 800 ft). 

Description of Study Area

Climate

The study area (fig. 1) has a continental climate marked 

by strong seasonality. Temperature and precipitation are 

affected by strong dry-cold air masses from the Northern 

Plains in the winter and by moist warm-air masses from the 

Gulf of Mexico during the summer months. These air masses 

travel relatively unimpeded by topographic features and may 

bring abundant amounts of precipitation particularly during 

the spring and summer months (National Climatic Data Center, 2008).

Mean air temperature for 1971–2000 varied seasonally, 

with the lowest mean monthly temperatures occurring in 

January and the highest in July. Mean monthly temperatures 

were lower in the northwestern part of the study area than 

in the southeastern part during the winter and spring months 

(November to April). For example, January mean temperatures 

ranged from 30.8oF in Chanute, Kansas, to 34.3oF in Fayetteville, Arkansas (fig. 2A). During the warmer months (May 

through October), there was less variation in mean monthly 

temperatures across the study area (generally 2oF or less), with 

warmer temperatures occurring toward the northwestern part 

of the study area. July temperatures ranged from 79.5oF in 

Chanute, Kansas, to 78.9oF in Fayetteville, Arkansas (National 

Climatic Data Center, 2008).

Mean monthly precipitation followed a seasonal pattern across the study area and was largest during the spring 

months (April to June) and smallest during the winter months 

(December to February). Generally, mean annual precipitation 

increased from northwest to southeast across the study area. 

For instance, mean annual precipitation for 1971–2000 ranged 

from 41.95 in. at Chanute, Kansas, to 46.02 in. at Fayetteville, 

Arkansas (fig. 2B). On a seasonal basis, Fayetteville tends to 

be wetter than Chanute, with the exception of the mid-summer 

months (July and August), during which Chanute received 

about 1 in. more rain on average than Fayetteville.

20

30

40

50

60

70

80

TEMPERATURE, IN DEGREES FAHRENHEIT

Chanute, Kansas

Fayetteville, Arkansas

0

1.00

2.00

3.00

4.00

5.00

6.00

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

PRECIPITATION IN INCHES

A. Mean monthly temperature

B. Mean monthly precipitation

Fayetteville, Arkansas

Chanute, Kansas

Figure 2. Mean monthly temperature and precipitation at 

Chanute, Kansas, and Fayetteville, Arkansas, for 1971–2000 (data 

from National Climatic Data Center, 2008).
6 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

Physiography

Most of the study area is contained within the Osage 

Plains physiographic section of the Central Lowland Province, 

and the Springfield Plateau physiographic section of the Ozark 

Plateaus Province (fig. 1) (Fenneman, 1938). Small parts of 

the Salem Plateau and Boston Mountains also are included in 

the study area. The Boston Mountains, Salem Plateau, Springfield Plateau, and St. Francois Mountains compose the four 

physiographic sections of the Ozark Plateaus Province. The 

province is underlain by a structural dome of igneous rock that 

forms the St. Francois Mountains and Paleozoic sedimentary 

rocks that underlie the other physiographic sections (fig. 3). 

The topography of these physiographic sections affects the 

hydrology of the study area.

The northwest segment of the study area falls within the 

Osage Plains physiographic section of the Central Lowland 

Province (fig. 1). The Central Lowland Province extends 

across most of the central United States, from North Dakota 

to Texas and from Missouri to Colorado. The Osage Plains 

covers the southeastern one-third of Kansas, west-central 

Missouri, most of central Oklahoma, and extends into northcentral Texas. The region is characterized by soft shale with 

interbedded sandstone and limestone of Late Mississippian to 

Pennsylvanian age. Topography in the Osage Plains is gently 

rolling, with some rare, east-facing escarpments. Land-surface 

altitudes range from 800 to 1,000 ft (Fenneman, 1938).

The southeast segment of the study area encompasses a 

large part of the Springfield Plateau physiographic section of 

the Ozark Plateaus Province (fig. 1). The Springfield Plateau 

extends from northeast to southwest across southwestern 

Missouri, southeastern Kansas, northwestern Arkansas, and 

northeastern Oklahoma. This section is underlain by limestone and cherty limestone of Mississippian age. Topography in this part of the study area is gently rolling hills, with 

some sinkholes and springs. Land-surface altitudes range 

from 1,000 to 1,700 ft; however, local topographic relief 

seldom exceeds 200 to 300 ft and decreases from east to west 

(Fenneman, 1938). 

The southern edge of the study area in Arkansas borders 

the Boston Mountains. Land-surface altitudes range from 

1,200 to more than 2,300 ft. Topography in the Boston Mountains is rugged, with local topographic relief exceeding several 

hundred feet in some places (Fenneman, 1938).

Geology

The geologic characteristics of the Ozark aquifer study 

area have been described in detail in several previous investigations (Macfarlane and Hathaway, 1987; Jorgensen, 1989; 

Imes and Emmett, 1994; Adamski and others, 1995; Jorgensen 

and others, 1996). A summary of these characteristics is presented in this report. 

The Ozark Plateaus aquifer system consists of six subdivisions. These units, from oldest to youngest, are the basement 

confining unit, St. Francois aquifer, St. Francois confining 

unit, Ozark aquifer, Ozark confining unit, and Springfield 

Plateau aquifer (fig. 3). These subdivisions are based on relative rock permeabilities and well yields, and coincide with 

the physiographic sections of the study area (fig. 1; Imes and 

Emmett, 1994). The Western Interior Plains aquifer system 

is adjacent to and west of the Ozark Plateaus aquifer system. 

The Western Interior Plains confining system overlies the 

Western Interior Plains aquifer system and the extreme western part of the Ozark Plateaus aquifer system.

The Ozark Plateaus aquifer system formed largely as a 

result of processes that favored marine carbonate sediment 

deposition modified by karstification during periods of subaerial exposure. It consists mainly of a Paleozoic sequence of 

sedimentary rocks of Cambrian to Mississippian age (table 1). 

The system is confined below by a basement confining unit 

of Precambrian age and above by the Western Interior Plains 

confining system of Pennsylvanian age (Macfarlane and 

Hathaway, 1987).

A basement complex of igneous and metamorphic rocks 

dating to Precambrian time underlies much of the central 

United States, including the study area. During the Precambrian, uplift diagenesis, referred to in the study area as the 

Ozark Uplift, formed a large land mass nearly 2,000 ft thick 

that became deeply eroded and faulted by Cambrian time (Jorgensen, 1989). Faulting and fracturing of the layer has resulted 

in anisotropic permeability that can facilitate ground-water 

flow (Jorgensen and others, 1996). 

During Early and Middle Cambrian time, the study 

area was above sea level. The climate was most likely warm 

and wet, with geological processes eroding and faulting 

the exposed Precambrian rock layer. Much of this area was 

engulfed by a marine sea during the Late Cambrian, which 

deposited permeable nearshore sand along with calcareous 

mud in some areas (Jorgensen and others, 1996). During this 

time, uplift diagenesis occurred during periods of marine 

recession that resulted in lithification of the sand and mud 

layers. These layers formed the sandstone and dolomite that 

are characteristic of the St. Francois aquifer and St. Francois 

confining unit (table 1). Connate marine water most likely 

was purged from the sediment during periods of recession. 

Secondary permeability resulted from erosion, which removed 

overburden load and caused extensional fracturing. This created paths along which dissolution occurred, especially that of 

calcareous material (Jorgensen, 1989). 

Since Cambrian time, the central United States has 

undergone relatively gentle deformation, resulting in upwarp 

and downwarp of the Earth’s crust over large areas. Ordovician time was likely warm and humid, and calcareous mud 

was the predominant sediment in shallow seas. Calcareous 

mud was lithified to limestone, especially during periods of 

recession. The limestone was dolomitized near coastlines, and 

erosion continued to cause extensional fracturing. Processes 

during this time tended to increase porosity and permeability 

(Jorgensen, 1989). 
Description of Study Area 7

WEST EAST CENTRAL LOWLAND OZARK PLATEAUS OZARK PLATEAUS Mississippi Alluvial Plain

ST. FRANCOIS

MOUNTAINS

APPROXIMATE

STUDY AREA

A

B

B1

B2

C D

E

F

G

H

H

G

F

E

I

WESTERN INTERIOR PLAINS CONFINING AND

 AQUIFER SYSTEM

 Western Interior Plains confining system

 Western Interior Plains aquifer system

 Stratigraphically equivalent to Ozark

 confining unit

 Stratigraphically equivalent to St. Francois

 confining unit

OZARK PLATEAUS AQUIFER SYSTEM

 Springfield Plateau aquifer

Ozark Plateaus confining unit and aquifer

 Ozark confining unit

 Ozark aquifer

A

B

C

D

E

B1

B2

St. Francois confining unit and aquifer

 St. Francois confining unit

 St. Francois aquifer

 Basement confining unit

MISSISSIPPI RIVER VALLEY ALLUVIAL AQUIFER

 Post-paleozoic sediment

 

F

G

H

I

NOT TO SCALE

EXPLANATION

Hydrogeologic unit

?

?

Indefinite boundary of transition zone between

fresh and saline ground water

?

Figure 3. Generalized geohydrologic section showing Ozark Plateaus aquifer system and adjacent hydrologic 

units (from Imes and Emmett, 1994).
8 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

During the Silurian and Devonian periods, the sea again 

receded and almost the entire study area underwent uplift 

diagenesis, resulting in extensional fracturing and the development of regional-flow systems of ground water (Adamski 

and others, 1995). These flow systems flushed out much of 

the existing formational water from previous layers, and the 

permeability of the exposed rocks was increased by erosional 

processes (Jorgensen, 1989). The result of these processes was 

the Ozark aquifer geohydrologic unit (table 1). 

Toward the end of the Devonian and the beginning 

of Mississippian time, the area was again inundated by a 

warm sea. Layers of sand were deposited near the shoreline, 

whereas clay was predominantly deposited offshore (Jorgensen and others, 1996). These extensive deposits of clay 

were characterized by very slight permeability that restricted 

the flow of water from the underlying carbonate rock layers to 

overlying sediment. 

The clay layers were covered by calcareous sediment by 

the cyclic, recessive sea of the Late Mississippian. Burial diagenesis further decreased porosity of the clay layer, ultimately 

creating the characteristic shale of the Ozark confining unit 

(table 1). The overlying calcareous sediment became lithified 

to the limestone of the Springfield Plateau aquifer as the Late 

Mississippian sea receded (table 1). 

The transgressions and regressions of the inland sea continued to advance and recede throughout the Pennsylvanian 

and Permian Periods and the Mesozoic and Cenozoic Eras. 

The study area continued to experience diagenetic processes 

that further formed the aquifer system and overlying topography. Gradual uplift continued to increase the altitude of the 

study area above sea level, and by the Mesozoic Era it was no 

longer being inundated. No significant deposition occurred in 

the Ozark Plateaus after the Pennsylvanian Period. By the end 

of the Permian, Pennsylvanian rocks that had been deposited 

around the St. Francois Mountains were being eroded, further 

developing and extending the regional ground-water flow 

system in the underlying permeable Cambrian and Ordovician 

rocks (Jorgensen, 1989; Adamski and others, 1995; Jorgensen 

and others, 1996). 

Geohydrology

Ground water in the Ozark Plateaus aquifer system 

flows from the Ozark Plateaus in the east towards the Western 

Interior Plains aquifer system in the west (fig. 3). The Ozark 

Plateaus aquifer system and the Western Interior Plains aquifer 

system are similar in that they both consist of dolostone, limestone, and sandstone. However, the water present in the Western Interior Plains aquifer system is briny, whereas the Ozark 

Plateaus aquifer system consists of fresh, nonsaline water. The 

freshwater mixes with the nearly stagnant saline water at a 

transition zone along the western edge of the Ozark Plateaus 

aquifer system (Macfarlane and Hathaway, 1987). 

Because soil and subsoil in the Ozark region is relatively 

thin and near-surface faults and fracture systems are common, 

precipitation may quickly infiltrate into the aquifer system. 

Rapid infiltration may allow surface contaminants to enter the 

ground-water system. Ground-water levels rise quickly after 

rainfall. This rapid infiltration causes widespread dissolution 

of the overlying carbonate rocks and helps flush out saline 

connate water to create a more freshwater system. Groundwater flow is almost entirely topographically controlled (Jorgensen, 1989). Ground water moving through the shallow part 

of the aquifer system follows short (usually less than 10 mi) 

local flow paths that terminate at nearby streams (Imes and 

Emmett, 1994). 

Igneous and metamorphic rocks of the basement confining unit underlie the study unit. The Precambrian batholith is 

exposed at the St. Francois Mountains (fig. 3). This highest 

point of the batholith remained exposed during some periods 

of deposition by advancing seas. Erosion has left the Precambrian rocks exposed. Precambrian rocks have some secondary 

permeability that is generated from fractures in the rocks (Jorgensen, 1989). They are used locally as a ground-water source 

where they crop out, although well yields are usually less than 

10 gal/min (Imes and Emmett, 1994).

The St. Francois aquifer lies beneath the Salem Plateau 

and St. Francois Mountains, and is separated from the Ozark 

aquifer by the St. Francois confining unit (figs. 1 and 3). The 

St. Francois aquifer is as much as 900 ft thick in Missouri 

and as much as 500 ft thick in northern Arkansas (Adamski 

and others, 1995). The St. Francois aquifer is rarely used as 

a drinking-water supply where overlain by the thicker Ozark 

aquifer. Because of this, its present-day potentiometric surface 

probably varies little from the predevelopment potentiometric 

surface. Wells penetrating this aquifer rarely yield more than 

50 gal/min, except those penetrating a significant thickness of 

the Lamotte Sandstone which may yield 100 to 500 gal/min 

(table 1, Imes and Emmett, 1994). The St. Francois confining 

unit hydraulically separates the Ozark aquifer from the underlying St. Francois aquifer and crops out around the St. Francois Mountains (fig. 3; Macfarlane and Hathaway, 1987). The 

thickness of the slightly permeable rocks of the confining unit 

averages between 200 and 400 ft (Imes and Emmett, 1994). 

The unconfined part of the Ozark aquifer extent coincides 

with the Salem Plateau physiographic section (fig. 1) and 

consists of a thick sequence of dolomite, sandstone, limestone, 

and shale (table 1). The Ordovician rocks range in thickness 

from about 300 ft in northeastern Oklahoma to nearly 4,000 ft 

in northern Arkansas, and the aquifer averages between 

1,500 and 2,000 ft thick throughout much of the study area 

(Imes, 1990). The aquifer is confined in the west by the Ozark 

confining unit but unconfined beneath much of the Salem 

Plateau (fig. 3; Imes and Emmett, 1994).

The potentiometric surface of the unconfined Ozark aquifer generally mimics the overlying topography. Exceptions 

to this are known to occur in karst areas where ground water 

can move through conduit flow systems across surface-water 

divides separating adjacent river basins. Ground-water levels 

in wells completed in this aquifer average from 700 to 1,000 ft 

above NAVD 88 over much of the Salem Plateau. Within the 
Description of Study Area 9

Table 1. Geologic and geohydrologic units in Ozark Plateaus aquifer system and adjacent areas, northwestern Arkansas, 

southeastern Kansas, southwestern Missouri, and northeastern Oklahoma (modified from Imes and Emmett, 1994).

Erathem System Southwestern 

Missouri

Southeastern 

Kansas

Northeastern 

Oklahoma

Northwestern 

Arkansas

Geohydrologic 

unit

PALEOZOIC

MISSISSIPPIAN

St. Louis Limestone

Salem Limestone

Warsaw Limestone

Keokuk Limestone

Burlington Limestone

Elsey Formation

Reeds Spring Limestone

Pierson Limestone

St. Louis Limestone

Salem Limestone

Warsaw Limestone

Keokuk Limestone

Burlington Limestone

Fern Glen Limestone

Moorefield Formation

Keokuk Limestone

Boone Formation

Reeds Spring Member

St. Joe Limestone 

Member

Boone Formation

Reeds Spring Member

St. Joe Limestone 

Member

SPRINGFIELD 

PLATEAU 

AQUIFER

Northview Shale

Sedalia Limestone

Compton Limestone

Chouteau Limestone Northview equivalent

Compton equivalent

OZARK 

CONFINING 

UNIT

DEVONIAN

Chattanooga Shale Chattanooga Shale

Woodford Chert

Chattanooga Shale Chattanooga Shale

Callaway Limestone

Fortune Formation

Absent Sallisaw Formation

Frisco Limestone

Clifty Limestone

Penters Chert

OZARK AQUIFER

SILURIAN

Absent Absent St. Clair Limestone

Lafferty Limestone

St. Clair Limestone

Brassfield Limestone

ORDOVICIAN

Kimmswick Limestone

Plattin Limestone

Joachim Dolomite

St. Peter Sandstone

Everton Formation

Smithville Formation

Powell Dolomite

Cotter Dolomite

Jefferson City Dolomite

Roubidoux Formation

Gasconade Dolomite

Van Buren Formation

Gunter Sandstone 

Member

Cotter Dolomite

Jefferson City Dolomite

Roubidoux Formation

Gasconade Dolomite

Van Buren Formation

Gunter Sandstone 

Member

Sylvan Shale

Fernvale Limestone

Viola Limestone

Fite Limestone

Tyner Formation

Burgen Sandstone

Smithville Formation

Powell Dolomite

Cotter Dolomite

Jefferson City Dolomite

Roubidoux Formation

Gasconade Dolomite

Van Buren Formation

Gunter Sandstone 

Member

Cason Shale

Fernvale Limestone

Kimmswick Limestone

Plattin Limestone

Joachim Dolomite

St. Peter Sandstone

Everton Formation

Smithville Formation

Powell Dolomite

Cotter Dolomite

Jefferson City Dolomite

Roubidoux Formation

Gasconade Dolomite

Van Buren Formation

Gunter Sandstone 

Member

CAMBRIAN

Eminence Dolomite

Potosi Dolomite

Eminence Dolomite

Potosi Dolomite

Eminence Dolomite

Potosi Dolomite

Eminence Dolomite

Potosi Dolomite

Doe Run Dolomite

Derby Dolomite

Davis Formation

Doe Run Dolomite

Derby Dolomite

Davis Formation

Doe Run Dolomite

Derby Dolomite

Davis Formation

Doe Run Dolomite

Derby Dolomite

Davis Formation

ST. FRANCOIS 

CONFINING 

UNIT

Bonneterre Dolomite

Reagan Sandstone

Lamotte Sandstone

Bonneterre equivalent

Reagan Sandstone

Lamotte Sandstone

Bonneterre equivalent

Reagan Sandstone

Lamotte Sandstone

Bonneterre Dolomite

Reagan Sandstone

Lamotte Sandstone

ST. FRANCOIS 

AQUIFER

PRECAMBRIAN IGNEOUS AND METAMORPHIC ROCKS

BASEMENT 

CONFINING 

UNIT
10 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

study area, the potentiometric surface generally increases from 

600 to 700 ft in the northwest to 1,200–1,300 ft in the southeast. Major pumping centers are marked by sharp decreases 

in ground-water levels, particularly in northeastern Oklahoma 

and southwestern Missouri (Gillip and others, 2008). Precipitation recharges the Ozark aquifer where it is unconfined. 

Ground water flows mostly laterally from the higher altitudes 

to points of discharge in springs and seeps along streams and 

downgradient to Kansas and Oklahoma. The confined part of 

the Ozark aquifer is recharged by lateral ground-water flow 

from the unconfined area and, in places, by leakage through 

the overlying confining unit. Deep wells in the Salem Plateau 

may yield more than 1,000 gal/min. Shallow domestic wells 

typically yield only 25 gal/min or less (Imes and Emmett, 

1994). 

The Ozark confining unit overlies the Ozark aquifer, 

averages about 60 to 80 ft in thickness, but can reach a thickness of 120 ft in southeastern Kansas (Adamski and others, 

1995). The shale and dense limestone in the Ozark confining 

unit hydraulically separate the overlying Springfield Plateau 

aquifer from the underlying Ozark aquifer. The confining unit 

is not present in the Salem Plateau where the Ozark aquifer is 

unconfined (fig. 3; Imes and Emmett, 1994). 

The Springfield Plateau aquifer coincides with the 

Springfield Plateau (fig. 1) and consists of limestone and 

cherty limestone of Mississippian age. The aquifer is confined by the Western Interior Plains confining system where 

it underlies the Boston Mountains and Osage Plains and 

unconfined where it underlies the Springfield Plateau (fig. 3; 

Imes and Emmett, 1994). The thickness of the aquifer ranges 

from about 100 ft in south-central Missouri to about 400 ft 

in southeastern Kansas (Adamski and others, 1995). The 

potentiometric surface of the unconfined Springfield Plateau 

aquifer generally reflects the overlying topography. Groundwater levels range from 700 ft above NAVD 88 in west-central 

Missouri, eastern Kansas, and northeastern Oklahoma, to 

more than 1,400 ft above NAVD 88 in southwestern Missouri 

and northwestern Arkansas (Gillip and others, 2008). The 

unconfined part of the Springfield Plateau aquifer is recharged 

nearly everywhere by precipitation. Wells penetrating this 

aquifer commonly yield less than 20 gal/min. Because of this, 

the aquifer is rarely used for public supply. However, springs 

from the aquifer have been used as a water source for towns in 

Arkansas, Missouri, and Oklahoma, (Imes and Emmett, 1994). 

The Western Interior Plains confining system coincides 

with the Boston Mountains physiographic section in the 

south and the Osage Plains physiographic section in the west 

(fig. 1). Rocks of Late Mississippian to Pennsylvanian age 

form the near-surface confining system (table 1). Lithologies 

include relatively permeable sandstone and limestone beds 

separated by thick layers of impermeable shale that result in 

an overall small permeability. The system is from 40 to 800 

ft thick in the Osage Plains but averages between 1,500 and 

2,000 ft in thickness in the Boston Mountains (Adamski and 

others, 1995). Regionally, the unit impedes the vertical and lateral flow of water. Wells in the area typically have small yields 

and are used only for domestic and stock supplies (Imes and 

Emmett, 1994). 

Methods of Investigation

Methods for the water-quality investigation of the Ozark 

aquifer described in this report included components of well 

selection, sample collection, sample analyses, and qualityassurance procedures for verification of analytical results. 

Additional procedures were conducted at a large-capacity 

municipal-supply well to determine aquifer geophysical characteristics and well-bore flow quantity and quality characteristics. Equipment used for onsite measurements of physical 

properties of ground water and borehole geophysics are listed 

in table 2.

Well Selection and Sample Collection

Within the study area, 40 water-supply wells were 

selected for collection of water-quality samples (table 3; 

fig. 4). Most of the wells (35) were water-supply wells, but 

three were for domestic use and two were for industrial use 

(table 3). The wells were selected on the basis of completion 

in and isolation of the Ozark aquifer. The wells were distributed spatially to provide as broad an assessment as possible of 

water-quality characteristics within the study area. Additional 

selection criteria included wells that were frequently pumped, 

accessible, and provided access to water at the wellhead prior 

to treatment practices such as chlorination or filtration.

The 40 wells were sampled once between September 19, 

2006 and June 1, 2007, for this reconnaissance assessment of 

the Ozark aquifer. Samples were collected and processed in 

a mobile water-quality laboratory. Teflon-lined polyethylene 

tubing was used to connect the well to the mobile laboratory. 

Generally, the tubing was connected to a sillcock or petcock 

valve or some other access point on the wellhead, and water 

was routed to the laboratory vehicle as the well was pumped. 

Because the sampled wells provide public or domestic water 

supplies, most, if not all, are pumped one to several times 

daily during periods of high demand.

Sampling and preservation protocols followed during 

this investigation are described in detail in Wilde and others 

(1999). To minimize the risk of sample contamination, all 

sample collection and preservation took place in dedicated 

environmental chambers consisting of clear polyethylene 

bags supported by tubular polyvinyl chloride (PVC) frames. 

Sampling equipment that extended from the sampling point 

near the wellhead to the sampling chamber inside the mobile 

laboratory was decontaminated thoroughly between each 

sample collection using a sequence of nonphosphate detergent 

wash and deionized water rinse.

If sampled wells were not pumping upon arrival, the 

operator/owner was asked to turn on the well pump. During the initial pumping period, measurements of specific 
Methods of Investigation 11

Table 2. Equipment used for onsite measurements of physical properties of ground water and borehole geophysics.[μS/cm, microsiemens per centimeter at 25 degrees Celsius; oC, degrees Celsius, mg/L, milligrams per liter; mV, millivolts; NTU, nephelometric turbidity units; ohm/meters, ohms per meter; mmho/m, microohms per meter; in., inch; cm, centimeter; cps, counts per second]

Physical property Instrument1 Range of possible measurement Resolution Accuracy

Specific conductance YSI 600XL multiparameter water-quality 

monitor, 6560 Sensor

0 to 100 μS/cm 0.001 to 0.1 μS/cm 

(range dependent)

±0.5 percent of reading + 0.001 

μS/cm

pH YSI 600XL multiparameter water-quality 

monitor, 6561 Sensor

0 to 14 standard units 0.01 standard unit ±0.2 standard unit

Temperature YSI 600XL multiparameter water-quality 

monitor, 6560 Sensor

-5 to +50°C 0.01°C ±0.15°C

Dissolved oxygen YSI 600XL multiparameter water-quality 

monitor, 6562 Rapid PulseTM Sensor

0 to 50 mg/L 0.01 mg/L 0 to 20 mg/L: ±0.2 mg/L or 2 

percent of reading, whichever 

is greater; 20 to 50 mg/L: ±6 

percent of reading

Oxidation-reduction potential YSI 600XL multiparameter water-quality 

monitor

-999 to +999 mV 0.1 mV ±20 mV

Physical property Instrument1 Range of possible measurement Estimated detection limit

Turbidity Hach 2100P Turbidimeter 0 to 1,000 NTU 0.01 NTU on lowest 

range

Borehole geophysics Instrument1 Range of possible measurement Accuracy

Natural gamma Century Geophysical 9144 Series E-Logging 

Tool

0-400,000 cps ±5 percent

Natural gamma Century Geophysical 9512 Logging Tool 0 to 10,000 cps ±5 percent16-in. (16N) & 64-in. Normal (64N) & 

lateral resistivity (LR)

Century Geophysical 9144 Series E-Logging 

Tool

0-2,000 ohm/meters ±5 percent

Fluid resistivity Century Geophysical 9144 Series E-Logging 

Tool

0-100 ohm meters ±5 percent

Specific conductance Century Geophysical 9512 Logging Tool 5 to 3,000 mmho/m ±5 percent @ 

30 mmho/m

Borehole caliper Century Geophysical 9074 Series Three Arm 

Caliper, model 7074 short-arm caliper

5.1 to 76.2 cm 

(2 to 30 in.) 

+/-0.38 cm (0.15 in.)

1YSI (YSI Incorporated, Yellow Springs, Maryland).

Hach (Hach Company, Loveland, Colorado).Century Geophysical (Century Geophysical Corporation, Tulsa, Oklahoma).
12 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

Table 3. Selected well information for sampled water-supply wells completed in Ozark aquifer, northwestern Arkansas, southeastern 

Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07.

[USGS, U.S. Geological Survey; bls, below land surface; --, not available]

Map index number 

(fig. 4)

USGS site identification 

number

Sampling date

(month/day/year)

Depth of well, bls 

(feet) Water use

Kansas

1 373821094372401 9/19/2006 -- Water supply

2 372512094464201 9/19/2006 -- Water supply

3 372725094443101 9/19/2006 1,113 Water supply

4 372440094384201 9/20/2006 1,045 Water supply

5 372111094464101 9/19/2006 970 Water supply

6 372418094400801 9/20/2006 1,050 Water supply

7 371847094461601 9/20/2006 -- Water supply

8 371413094484701 10/11/2006 1,100 Water supply

9 371037094503501 9/21/2006 -- Water supply

10 371012094421801 9/29/2006 900 Water supply

11 370701094403001 9/21/2006 -- Water supply

12 370430094481401 9/21/2006 1,050 Water supply

13 370430094375201 9/22/2006 1,177 Water supply

14 370426094413501 9/29/2006 1,204 Water supply

15 370246094441301 9/22/2006 1,175 Water supply

Missouri

16 373633094000301 5/29/2007 1,215 Water supply

17 372551094254101 12/13/2006 900 Water supply

18 372028093421501 5/29/2007 892 Water supply

19 371937094180801 12/13/2006 1,505 Water supply

20 371219094302401 5/30/2007 1,265 Water supply

21 371251093564101 12/11/2006 1,250 Industrial

22 371116094333901 5/30/2007 920 Water supply

23 370313094214601 12/12/2006 1,518 Industrial

24 370249093470001 12/11/2006 410 Water supply

25 365620094000701 12/12/2006 1,309 Water supply

26 365539093475101 12/12/2006 715 Domestic

27 365006094361601 5/30/2007 1,456 Water supply

28 364541094113101 5/31/2007 950 Water supply

29 364010093555901 5/31/2007 1,002 Water supply

30 363312094291001 5/30/2007 800 Water supply

Oklahoma

31 365905094470701 5/22/2007 1,110 Water supply

32 365447094502401 5/22/2007 1,108 Water supply

33 365242095051701 5/21/2007 1,200 Water supply

34 364807094434201 5/23/2007 1,150 Water supply

35 364759095041401 5/23/2007 1,418 Water supply

36 363741094553201 5/24/2007 1,500 Water supply

37 362532094375501 5/24/2007 1,160 Domestic

38 362427094493001 5/24/2007 1,442 Water supply

Arkansas

39 361025094253501 6/1/2007 700 Domestic

40 360509094224101 6/1/2007 1,815 Water supply
Methods of Investigation 13

Galena Joplin

Carthage Mt Vernon

 Monett

 Cassville

 Aurora

Neosho

Bentonville

Eureka

Springs

Fayetteville Huntsville

Gravette

Baxter Springs

Oswego Columbus

Vinita

Nowata

Claremore

Pryor Jay

Independence

Miami

Lamar

Greenfield

Nevada

Stockton

Osceola

Pittsburg

Arcadia

Parsons

Erie

Chanute

Yates Center

Iola

Fort Scott

MISSOURI

KANSAS

North Fork Spring River

Sac River

Sac River

Marmaton River

Neosho River

Pineville

KANSAS

OKLAHOMA

OKLAHOMA

ARKANSAS

ARKANSAS

MISSOURI

Illinois

River

Beaver

Reservoir

Lake Hudson

Grand Lake O' the Cherokees

Oologah Lake

Table Rock Lake

Kings River

River

Spring River

Fall River

River

Verdigris River

Neosho River

Roaring

Spring River

Stockton Lake

Elk

Empire Lake

Little Osage River

Osage River

Study area

9

8

7

6 5

3

2

1

40

39

38 37

36

35 34

33

32

31

30

29

28

27

26

25

23 24

22

21 20

19

18

17

16

15

14 13 12

11

10

4

PCW-10

0 5 10 15 20 MILES

0 5 10 15 20 KILOMETERS

EXPLANATION

40

Boundary of study area

Water-supply well and 

 map index number

Pittsburg city well 10

 

Base from U.S. Geological Survey digital data, 1999, 1:100,000

Universal Transverse Mercator projection

Zone 15

Horizontal coordinate information is referenced to the North American

 Datum of 1983 (NAD 83)

95°45'

45'

37°

38°

30' 15' 95° 45' 30' 15' 94°

36°

45'

30'

30'

15'

15'

PCW-10

Fort Gibson

Lake

MISSOURI

KANSAS

OKLAHOMA

ARKANSAS

Index map

Study

area

93°30'

45'

Figure 4. Map showing location of 40 water-supply wells sampled as part of an assessment of ground-water quality in Ozark aquifer, 

northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07.
14 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

conductance, pH, water temperature, dissolved oxygen, and 

oxidation-reduction potential (ORP) were monitored every 5 

minutes in a closed-cell, flow-through chamber until stable 

readings were obtained. Turbidity also was measured every 5 

minutes using a portable turbidity meter. Once stable readings 

of these physical properties were obtained, water flow inside 

the mobile laboratory was redirected to the clean sampling 

chamber where sample water was collected for processing and 

preservation. Constituents analyzed in water samples are listed 

in table 13 in the “Supplemental Information” section at the 

back of this report.

Samples analyzed for major ions, nutrients, and trace 

elements were filtered through a 0.45-μm pore-size disposable-capsule filter and collected in precleaned plastic bottles 

that were rinsed onsite with filtered ground water. Samples 

analyzed for concentrations of major cations and trace elements were preserved to a pH of less than 2.0 standard units 

using ultrapure nitric acid. A filtered, unpreserved sample was 

collected for major anion analysis. Additionally, an unfiltered 

sample was collected for onsite titration of carbonate alkalinity (acid neutralizing capacity). Nutrient samples were filtered 

(0.45-μm pore size) into onsite-rinsed brown plastic bottles 

and were chilled on ice, with no preservation, and delivered to 

the analyzing laboratory within 24 hours.

Sample Analysis

Analysis of all water-quality samples, except the determination of strontium isotope ratio, was performed by the USGS 

National Water-Quality Laboratory (NWQL) in Lakewood, 

Colorado, or its contract laboratory according to methods 

listed in table 4. Determination of strontium isotope ratio was 

performed at the University of Colorado, Department of Geological Sciences, Boulder, Colorado. Strontium was separated 

from the water samples using an ion-specific resin (SrSpec 

from Eichrom Industries, Lisle, IL) in a Class 100 clean room. 

Strontium isotope measurements were performed on a Finnigan-MAT 261 thermal ionization mass spectrometer (Finnigan 

MAT, San Jose, CA). All data were obtained in four-collector 

static mode and normalized to strontium-86/strontium-88 

(86Sr/88Sr=0.1194). Results of all physical measurements and 

chemical analyses of water samples from the 40 selected wells 

are listed in tables 13–16 in the “Supplemental Information” 

section at the back of this report.

Geophysical Logging, Well-Bore Flow, and 

Depth-Dependent Sampling

The combination of borehole geophysical information 

and well-bore flow and depth-dependent water-quality data 

can be effective in assessing differences in aquifer properties 

and water quality with depth (Izbicki and others, 1999). These 

data may help to identify different water-bearing units with 

depth, changes in natural ground-water chemistry with depth, 

and human-related or natural contaminants with depth. The 

underlying utility of this combined hydrogeologic information 

is the potential identification of contaminant origin and the 

flow path through which the contamination may have entered 

the well. Sources of contamination may be from lateral flow 

or possibly through vertical migration from deeper or overlying geologic formations. Sampling in a large-capacity well 

while pumping would maximize the chance of observing the 

Table 4. Laboratory analysis methods for measured water-quality constituents. 

[USGS, U.S. Geological Survey; NWQL, National Water-Quality Laboratory; ICPMS, inductively coupled plasma mass spectrometry; C, Carbon; O, oxygen; 

S, sulfur; Sr, strontium]

Constituent group Analysis method Method reference

Major ions (USGS schedule 2750) Atomic absorption spectrometry, ICPMS Fishman (1993)

Trace elements (USGS schedule 2710, 

laboratory code 2707)

Atomic absorption spectrometry, ICPMS Faires (1993)

Nutrients (USGS schedule 2752) Various methods Fishman (1993); Patton and Kryskalla 

(2003)

Isotopes

Deuterium/Protium ratio (USGS laboratory 

code 1574)

Gaseous hydrogen equilibration Coplen and others (1991)

Tritium (USGS laboratory code 2770) Electrolytic enrichment, beta counting Thatcher and Janzer (1977)

14C (USGS laboratory code 2010) Accelerator mass spectrometry Beukens (1992)

13C/12C ratio (USGS 440) Mass spectrometry Gleason and others (1969)

18O/16O ratio (USGS laboratory code 489) Mass spectrometry Epstein and Mayeda (1953)

34S/32S ratio (USGS laboratory code 1951) Isotope ratio mass spectrometry Révész and Qi (2006)

87Sr/86Sr ratio Mass spectrometry See description in “Sample Analysis” section 

of text
Methods of Investigation 15

migration of contaminants to the well. Knowledge of potential 

contaminant flow paths may provide ground-water managers with the information needed to implement operational or 

conservation measures to mitigate contaminant flux, thereby 

increasing utility and useful life of the resource and reducing 

potential treatment costs.

A water-supply well in the Pittsburg, Kansas, well field 

was selected as a representative location in a major pumping center from which to evaluate geophysical and well-bore 

and water-quality (vertical variability) characteristics in the 

Ozark aquifer. This well (Pittsburg city well 10, PCW-10) is 

located about 0.25 mi south of Pittsburg city well 8, PCW-8, 

which is well 6 in figure 4 that was sampled as part of the 

spatial-distribution, water-quality assessment described in this 

report. Geophysical logging was conducted in well PCW-10 

on June 8, 2007, during a period of well maintenance when 

the pump was removed. Logging included measurements of 

borehole caliper, natural gamma, specific conductance, normal 

and lateral resistivity, fluid resistivity, and water temperature 

(table 2). These measurements were made using equipment 

supplied by and personnel from the USGS Texas Water Science Center, Austin, Texas.

Vertical variability in well-bore flow (velocity-log 

data) and water quality was determined in well PCW-10 

using a well-bore flow and depth-dependent water sampler 

(Izbicki and others, 1999). This device is a high-pressure 

hose equipped with valves for dye injection and sample 

collection under pumping conditions. The hose is mounted 

on a power-driven reel and can be used to collect velocitylog data and, after appropriate cleaning, depth-dependent 

water-quality samples.

Velocity-log data were collected using a water/Rhodamine dye mixture (tracer) and a “tracer-pulse method” of 

injecting the dye mixture into the borehole flow. When using 

this method, the hose is filled with the dye mixture, lowered 

to a specific depth, and a pulse of the mixture is injected. The 

travel time of the dye to a fluorimeter at the surface is measured. The process was repeated at about 10-ft intervals from 

the bottom of the well casing at 550 ft bls (below land surface) 

to the bottom of the borehole at 1,050 ft bls. The velocity was 

calculated as the difference in traveltimes between successive 

intervals. Using diameter of the borehole and interval velocities, flow volume for each interval was calculated along with 

the volume of water entering each interval from the geologic 

formations. Velocity-log data were collected from well PCW10 on August 6–7, 2007, at a pumping rate of 2,300 gal/min 

using equipment provided by and personnel from the USGS 

Oklahoma Water Science Center, Oklahoma City, Oklahoma.

Depth-dependent water-quality samples were collected 

from well PCW-10 on August 13–14, 2007, while the well 

was pumping at a rate of 1,900 gal/min. The well had been 

pumping continuously at about this rate since velocity-log 

data were collected on August 6–7, 2007. The same equipment used by the same personnel that collected the velocitylog data were used to collect water-quality samples after 

thorough cleaning and decontamination of the collection 

hose with a nonphosphate soap and deionized-water rinse to 

remove residual traces of the dye mixture and other potential 

contaminants. To collect a water-quality sample at a specific 

depth, the hose was pressurized with nitrogen gas to greater 

than the hydrostatic pressure at the specific depth and lowered into the well. At the desired sample depth, the hose was 

vented at the surface allowing water to enter the hose through 

a one-way valve. The hose was retrieved, and the collected 

sample drained from the hose and subsequently processed into 

subsamples for analyses of selected water-quality constituents. 

Samples were collected at 487, 687, 787, 877, 937, and 1,030 

ft bls and at the well head. The sample at 487 ft bls was collected from between the well casing and the pump discharge 

pipe. Each sample represents the average cumulative constituent concentration of all the water in the vertical profile below 

it. Samples were processed and analyzed using the same methods and procedures as previously outlined in previous sections 

of this report.

Unstable Isotope Analysis

The radionuclide carbon-14 14C has been used since the 

1950s to age date materials or compounds containing carbon. 

14C is produced continuously in the atmosphere by the reaction of cosmic ray neutrons on 14C and has a decay half-life 

of 5,730 years. Concentrations of 14C usually are reported 

as activity referenced to an international standard known as 

“modern carbon” and is defined as 95 percent of the 14C activity in 1950 according to the National Bureau of Standards 

oxalic acid standard (Clark and Fritz, 1997). Measured 14C 

activity is expressed as a percentage of modern carbon (pmC) 

(Clark and Fritz, 1997). The radiocarbon age of dissolved inorganic carbon (DIC) in ground water is obtained by measurement of residual radioactivity and compared with the activity 

in a modern carbon standard. The method is useful for dating 

carbon-containing material in the range of 1,000 to 40,000 

years (Kendall and others, 1995). Carbon-dead water has no 

14C activity. Dilution of younger water with carbon-dead water 

results in errors.

Tritium is produced naturally in small amounts of cosmic 

radiation but was distributed in much greater quantities by 

atmospheric testing of thermonuclear weapons between 1951 

and 1980 (Clark and Fritz, 1997). Tritium has a decay halflife of 12.32 years. The occurrence of tritium in ground water, 

therefore, can be used as an indicator of modern (after 1952) 

recharge. If the level of tritium in water is less than 2.6 pCi/L, 

it is considered “dead” water and indicates that the ground 

water came from water recharged before 1952.

Quality Assurance

Quality-assurance samples collected included concurrentreplicate environmental samples, source-water blanks, and 

equipment blanks. Replicate environmental samples were 

used to assess the combined effects of onsite and laboratory 
16 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

procedures on measurement variability. Blank samples were 

used to verify that decontamination procedures were adequate 

and that onsite and laboratory protocols and sample shipment 

did not contaminate the samples.

A concurrent-replicate sample for the study described 

in this report is defined as one where subsamples (individual 

sample bottles or containers) within a sample set (group of 

bottles or containers) were filled immediately after the equivalent bottle for the primary environmental sample. For instance, 

the concurrent-replicate bottle for nutrient analyses was filled 

immediately after the same bottle for the primary sample, and 

so forth. This alternating sequence was continued until both 

the primary and replicate sample sets were collected.

A target goal for variability among analyses of concurrent-replicate samples was a relative percentage difference 

(RPD) of ±20 percent except when constituent concentrations were at or near the method reporting limit (MRL) for 

that constituent (table 13 in the “Supplemental Information” 

section at the back of this report). RPD was calculated as 

the difference in replicate analyses divided by the mean and 

expressed as a percentage. RPDs between paired constituent 

concentrations were calculated and summarized (table 5) if a 

constituent was detected at greater than the MRL, or if it was 

detected at less than the MRL and reported as an estimated 

value. An RPD was not calculated for a replicate pair if one or 

both analyses were reported as less than the MRL. Concurrentreplicate samples consisted of subsamples collected (from 

same sampling site) during the same sampling procedure. 

Four pairs of concurrent-replicate ground-water samples were 

collected during the study described in this report. No RPDs 

were available for nitrite, phosphorus, aluminum, antimony, 

beryllium, cadmium, cobalt, silver, thallium. Most RPDs 

were less than the ±20-percent target except for bromide, total 

nitrogen, orthophosphate, chromium, mercury, nickel, selenium, uranium, and zinc where replicate values were at or near 

the MRLs. In addition RPD exceeded the target goal for 14C, 

where no MRL is specified, and for copper and tritium where 

replicate values were not less than the MRL. The maximum 

RPDs were 24 percent for copper; 29 percent for 14C; and an 

anomalously large 640 percent for tritium. For wells with replicate analyses, analytical results of these paired samples were 

averaged prior to assessment, presentation, and discussion in 

this report. Cation/anion balance had to be within 5 percent to 

be acceptable.

Five blank samples were analyzed for specific conductance and concentrations of major ions, nutrients, and trace 

elements (table 6). One source-water blank and four equipment blank samples were produced. The source-water blank 

sample (blank 1) was prepared by collecting deionized water 

at a USGS office and subjecting it to bottling, preservation, 

and shipping protocols only. Two constituents were found in 

blank 1, but in small, estimated concentrations—ammonia 

(0.01 mg/L) and mercury (0.007 μg/L), both less than the 

MRL. Equipment-blank solutions (blank samples 2–5) passed 

through all sampling equipment and were collected using the 

same protocols as for environmental samples. Blank samples 

2, 4, and 5 were prepared with the equipment used to sample 

wells in Arkansas, Kansas, and Missouri. Blank samples 2 and 

5 were prepared at a USGS office, but blank sample 4 was 

produced onsite during sample collection. Blank sample 3 was 

produced at the USGS Oklahoma Water Science Center (Oklahoma City) with the equipment used to sample the Oklahoma 

water-supply wells.

Several constituents were found in the equipment 

blank samples, although in relatively small concentrations. 

Blank sample 2 had a specific conductance of 3.0 μS/cm 

and contained ammonia (estimated 0.01 mg/L), total nitrogen (0.08 mg/L), barium (1.4 μg/L), chromium (estimated 

0.05 μg/L), copper (0.6 μg/L), lead (estimated 0.06 μg/L), 

mercury (estimated 0.006 μg/L), nickel (0.15 μg/L), and 

zinc (1.2 μg/L). Blank sample 3 had a specific conductance 

of 22 μS/cm and contained calcium (0.05 mg/L), chloride 

(0.5 mg/L), silica (0.1 mg/L), total nitrogen (estimated 

0.04 mg/L), barium (0.3 μg/L), lead (estimated 0.11 μg/L), 

mercury (estimated 0.007 μg/L), and zinc (0.7 μg/L). Water 

from blank sample 4 had a specific conductance of 4 μS/cm, 

and only one chemical constituent was present in a measurable 

quantity, total nitrogen, estimated at 0.05 mg/L (less than the 

MRL of 0.06 mg/L). Blank sample 5 contained dissolved solids (13 mg/L), barium (presence verified but not quantified), 

copper (0.73 μg/L), and zinc (1.4 μg/L). 

In general, the results of equipment-blank analyses are 

comparable with the exception of calcium, chloride, and silica, 

which were detected only in blank sample 3. Source water 

may provide trace amounts of contamination in the form of 

ammonia and mercury. The constituents that were detected 

in the equipment blanks and not found in the source-water 

blank were dissolved solids, total nitrogen, barium, chromium, 

copper, lead, nickel, and zinc. Thus, sampling equipment and 

protocols may provide trace contamination from these constituents. The most significant contamination came in the form 

of copper and zinc, which were detected in equipment blanks 

at concentrations greater than the minimum found in the 

40 water-supply wells sampled in the study. Small concentrations (especially near the MRLs) of these constituents in environmental samples may be the result of contamination from 

equipment. However, because of a 20- to 30-minute purge of 

sampling equipment with well water prior to sample collection 

at each site, contamination from cleaning procedures or “carry 

over” between wells is believed to be insignificant.

Qualitative data remark codes may be associated with 

water-quality data presented in this report (tables 13–18 in the 

“Supplemental Information” section at the back of this report). 

For instance, many trace-element concentrations (table 17) 

were reported as “less than” (<) an analytical method reporting limit. Also, many concentrations that were quantifiable but 

less than established method reporting limits were reported 

as estimated (E). All of these data were used in statisticalanalysis applications presented in this report. For percentile 

and median concentration determinations, “less than” qualified data were ranked according to their numeric value before 

the corresponding nonqualified numeric values (assuming a 
Methods of Investigation 17

Table 5. Statistical summary of absolute relative percentage differences (RPDs) between selected water-quality constituents 

in concurrently collected replicate samples of ground water from water-supply wells completed in Ozark aquifer, northwestern 

Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07.

[N, number of replicate pairs; --, not determined; δ, del; C, carbon; H, hydrogen; O, oxygen; S, sulfur; Sr, strontium]

Constituent Absolute relative percentage difference

N Minimum Median Mean Maximum

Major ions

Dissolved solids 4 0 1.0 2.0 6.1

Calcium 4 0 .9 1.3 3.3

Magnesium 4 0 0 1.9 7.4

Potassium 4 0 0 .5 1.9

Sodium 4 0 0 .3 1.2

Alkalinity 3 0 0 0 0

Bicarbonate 3 0 0 0 0

Bromide 3 0 3.4 23 67

Chloride 4 0 0 0 0

Fluoride 4 0 2.7 3.4 8.0

Silica 4 0 .5 .5 1.1

Sulfate 4 0 0 .5 2.2

Nutrients

Nitrogen, ammonia, as nitrogen 3 0 0 1.6 4.7

Nitrogen, nitrite plus nitrate, as 

nitrogen

1 -- -- -- 8.7

Nitrogen, nitrite, as nitrogen 0 -- -- -- --

Total nitrogen 3 0 4.4 18 50

Orthophosphate, as phosphorus 4 0 0 7.1 29

Phosphorus 0 -- -- -- --

Trace elements

Aluminum 0 -- -- -- --

Antimony 0 -- -- -- --

Arsenic 2 6.1 6.3 6.3 6.5

Barium 4 0 0 0 0

Beryllium 0 -- -- -- --

Boron 4 0 4.9 4.4 7.6

Cadmium 0 -- -- -- --

Chromium 1 -- -- -- 140

Cobalt 0 -- -- -- --

Copper 1 -- -- -- 24

Iron 3 0 2.6 3.3 7.4

Lead 2 8 12 12 15

Lithium 4 1.1 4.2 4.3 7.6
18 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

Table 5. Statistical summary of absolute relative percentage differences (RPDs) between selected water-quality constituents 

in concurrently collected replicate samples of ground water from water-supply wells completed in Ozark aquifer, northwestern 

Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07.—Continued

[N, number of replicate pairs; --, not determined; δ, del; C, carbon; H, hydrogen; O, oxygen; S, sulfur; Sr, strontium]

Constituent Absolute relative percentage difference

N Minimum Median Mean Maximum

Trace elements

Manganese 4 0 2.7 2.9 6.2

Mercury 1 -- -- -- 25

Molybdenum 3 0 8.0 6.2 11

Nickel 4 0 23 34 91

Selenium 2 40 45 45 50

Silver 0 -- -- -- --

Strontium 4 0 1.2 1.0 1.4

Thallium 0 -- -- -- --

Uranium 4 0 6.9 9.0 22

Vanadium 1 -- -- -- 0

Zinc 2 11 61 61 110

Isotopes

δ13C 2 1.2 1.8 1.8 2.5

14C 2 22 25 25 29

δ2H 2 .2 .4 .4 .5

Tritium 2 42 340 340 640

δ180 2 .6 .8 .8 .9

δ34S 2 .5 .8 .8 1.2

87Sr/86Sr 2 0 0 0 0
Methods of Investigation 19

Table 6. Results of analyses of source water used to decontaminate sampling equipment between sample collections and 

equipment-blank samples processed with source water, 2006–07. 

[μS/cm, microsiemens per centimeter at 25 degrees Celsius; <, less than; N, nitrogen; E, estimated quantity; P, phosphorus; M, presence verified but not 

quantified]

Blank type, date, physical 

property, or constituent

Blank sample 

1 2 3 4 5

Blank type Source water Equipment Equipment Equipment Equipment

Date (month/day/year) 9/13/2006 9/13/2006 5/21/2007 6/1/2007 8/7/2007

Physical properties

Specific conductance (μS/cm) <2.6 3.0 22 4.0 <2.6

Dissolved solids and major ions, in milligrams per liter

Dissolved solids <10 <10 <10 <10 13

Calcium <.02 <.02 .05 <.02 <.02

Magnesium <.008 <.008 <.014 <.014 <.014

Sodium <.20 <.20 <.20 <.20 <.20

Potassium <.16 <.16 <.04 <.04 <.04

Sulfate <.18 <.18 <.18 <.18 <.18

Chloride <.20 <.20 .50 <.12 <.12

Fluoride <.10 <.10 <.10 <.10 <.10

Bromide <.02 <.02 <.02 <.02 <.02

Silica <.04 <.04 .10 <.018 <.02

Nutrients, in milligrams per liter

Ammonia, as N E.01 E.01 <.010 <.02 <.020

Nitrite plus nitrate, as N <.060 <.060 <.060 <.060 <.06

Nitrite, as N <.002 <.002 <.002 <.002 <.002

Total nitrogen, as N <.06 .08 E.04 E.05 <.06

Orthophosphate, as P <.006 <.006 <.006 <.006 <.006

Phosphorus <.004 <.004 <.004 <.006 <.006

Trace elements, in micrograms per liter

Aluminum <1.6 <1.6 <1.6 <1.6 <1.6

Antimony <.20 <.20 <.06 <.06 <.06

Arsenic <.12 <.12 <.12 <.12 <.12

Barium <.20 1.4 .30 <.08 M

Beryllium <.06 <.06 <.06 <.06 <.06

Boron <8.0 <8.0 <8.0 <8.0 <8.0

Cadmium <.04 <.04 <.04 <.04 <.04

Chromium <.04 E.05 <.12 <.12 <.12

Cobalt <.04 <.04 <.04 <.04 <.04

Copper <.40 .60 <.40 <.40 .73

Iron <6.0 <6.0 <6.0 <6.0 <6.0

Lead <.08 E.06 E.11 <.12 <.12

Lithium <.60 <.60 <.60 <.60 <.60
20 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

ranking order from smallest to largest), and estimated values 

were ranked as nonqualified values in numerical sequence (for 

example, E1, <2, 2, E3, <5, 5, 8, 12, and so forth).

Quality Characteristics of Ground 

Water

Ground water in the Ozark aquifer is used to a limited 

extent for domestic supply but is used more extensively for 

public and industrial supplies and for irrigation. The USEPA 

has established drinking-water standards for physical properties and chemical constituents that may have adverse effects 

on human health or that may affect the odor, appearance, or 

desirability of water (U.S. Environmental Protection Agency, 

2006). These water-quality standards include Maximum Contaminant Levels (MCLs), Secondary Drinking-Water Regulations (SDWRs), and Maximum Contaminant Level Goals 

(MCLGs). An MCL is a regulatory, enforceable maximumpermissible concentration for a contaminant in drinking water 

that is delivered to any user of a public-water system. MCLs 

are set at levels to protect human health from all expected 

deleterious effects. An SDWR is a nonenforceable guideline 

regarding cosmetic (tooth or skin discoloration) or aesthetic 

(taste, odor, or color) effects of drinking water. An MCLG is a 

nonenforceable health goal that is set at a level with no known 

adverse human-health effects.

Results of physical measurements and chemical analyses 

of ground-water samples collected from 40 water-supply wells 

in the Ozark aquifer study area (fig. 4) are presented in tables 

14–17 in the “Supplemental Information” section at the back 

of this report. These data were assessed or evaluated in the 

context of spatial distribution and evolution along selected 

flow paths. Data were also assessed relative to USEPA 

drinking-water standards and to natural hydrologic factors or 

human-related activities. 

Spatial Distribution

The spatial distribution of water-quality characteristics 

throughout the study area was summarized statistically and 

assessed with the use of analysis of water samples from 40 

water-supply wells completed in the Ozark aquifer. Fifteen 

wells were located in each of Kansas and Missouri, eight in 

Oklahoma, and two in Arkansas (fig. 4). Well-selection criteria 

were discussed previously in the “Methods of Investigation” 

section of this report. Water-quality measurements or constituent groups assessed included physical properties, dissolved 

solids and major ions, nutrients, and trace elements, and 

selected isotopes.

Table 6. Results of analyses of source water used to decontaminate sampling equipment between sample collections and 

equipment-blank samples processed with source water, 2006–07.—Continued

[μS/cm, microsiemens per centimeter at 25 degrees Celsius; <, less than; N, nitrogen; E, estimated quantity; P, phosphorus; M, presence verified but not 

quantified]

Blank type, date, physical 

property, or constituent

Blank sample 

1 2 3 4 5

Blank type Source water Equipment Equipment Equipment Equipment

Date (month/day/year) 9/13/2006 9/13/2006 5/21/2007 6/1/2007 8/7/2007

Trace elements, in micrograms per liter—Continued

Managnese <0.20 <0.20 <0.20 <0.20 <0.20

Mercury E.007 E.006 E.007 <.010 <.010

Molybdenum <.40 <.40 <.12 <.12 <.10

Nickel <.06 .15 <.06 <.06 <.06

Selenium <.08 <.08 <.08 <.08 <.08

Silver <.20 <.20 <.10 <.10 <.10

Strontium <.80 <.80 <.80 <.80 <.80

Thallium <.04 <.04 <.04 <.04 <.04

Uranium <.04 <.04 <.04 <.04 <.04

Vanadium <.10 <.10 <.04 <.04 <.04

Zinc <.60 1.2 .70 <.60 1.4
Quality Characteristics of Ground Water 21

Physical Properties

 Physical properties were measured or analyzed in water 

from each of the 40 water-supply wells (fig. 4) sampled during this study (table 14 at the back of this report). Measurements made at the time of sample collection included specific 

conductance, pH, water temperature, dissolved oxygen, and 

turbidity, and oxidation-reduction (redox) potential. A statistical summary and USEPA standards for physical properties in 

water from the 40 wells sampled during this study are presented in table 7. 

Specific conductance describes the ability of water to 

conduct an electrical current and provides an indication of 

dissolved ions in solution. Specific conductance generally has 

a direct relation with major ion concentrations (Hem, 1992). 

Specific conductance of water from the sampled wells was 

less than 500 μS/cm for about one-half (21 of 40) of the wells, 

as indicated by the median value of 470 μS/cm (table 7). The 

other 19 wells had specific conductance values in the range of 

about 500 to 1,890 μS/cm (table 14). Generally, water from 

wells located in Missouri had the smallest specific conductance values, and overall, Kansas had the largest. However, the 

largest specific conductance (1,890 μS/cm) was determined in 

water from well 33 in Oklahoma (table 14, fig. 4).

The pH of water is a measure of the activity of the hydrogen ion and indicates the degree of acidity or alkalinity of a 

solution. A pH of less than 7.0 standard units is considered 

acidic, and a pH greater than 7.0 standard units is considered 

alkaline. The pH of water from sampled wells in the study area 

had a median value of 7.56 standard units (table 7). USEPA 

has established an SDWR range of 6.5 to 8.5 standard units 

(U.S. Environmental Protection Agency, 2006) in drinking 

water, and water from all sampled wells was within this 

guideline.

Oxygen enters ground water through recharge of 

oxygen-enriched surface or meteoric water that percolates 

down through the unsaturated zone where it may react with 

oxidizable material encountered along the flow path of the 

water. The main reacting compounds are organic material and 

reduced inorganic minerals such as pyrite and siderite (Hem, 

1992). Water from most of the 37 wells for which dissolved 

oxygen content was determined was relatively oxygen poor 

as indicated by a median dissolved oxygen concentration of 

0.16 mg/L (table 7). Six wells had no measurable dissolved 

oxygen content (less than 0.01 mg/L), 24 wells had dissolved 

oxygen concentrations that ranged from 0.01 to 0.28 mg/L, 

and the remaining 7 wells had dissolved oxygen concentrations that ranged from 1.4 to 2.0 mg/L (table 14). Because of 

the large depths of the wells sampled in this study (table 3), 

confined conditions, and potential for flow paths of tens of 

miles or more, the small concentrations of dissolved oxygen in 

ground water were not unexpected.

Turbidity refers to the cloudiness of water and is caused 

by suspended matter and other factors (Anderson, 2005). Turbidity is measured by quantifying the amount of light scattered 

by particles in the water and can be measured in nephelometric turbidity units (NTUs). Turbidity has no health effects, but 

it can interfere with disinfection and provide a medium for 

microbial growth. The USEPA established an MCL of 5 NTU 

(U.S. Environmental Protection Agency, 2006). The turbidity 

of water in the wells sampled generally was small as indicated 

by a median value of 0.20 NTU (table 7). However, three 

wells (1, 5, and 9; fig. 4) exceeded the water-quality standard 

Table 7. Statistical summary and U.S. Environmental Protection Agency (2006) drinking-water standards for physical properties 

measured or analyzed in ground water from 40 water-supply wells completed in Ozark aquifer, northwestern Arkansas, southeastern 

Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07. 

[μS/cm, microsiemens per centimeter at 25°C; °C, degrees Celsius; mg/L, milligrams per liter; NTU, nephelometric turbidity units; SHE, relative to standard 

hydrogen electrode; mV, millivolts; CaCO3, calcium carbonate; --, not applicable; MCL, Maximum Contaminant Level; SDWR, Secondary Drinking-Water 

Regulation]

Physical property 

(unit of measurement)

Number of 

samples Minimum

Percentile

Maximum Drinking-water 

25 standard 50

(median) 75

Specific conductance (μS/cm) 40 236 334 470 913 1,890 --

pH (standard units) 40 6.84 7.35 7.56 7.75 8.15 6.5–8.5 (SDWR)

Water temperature (°C) 40 15.3 18.2 19.5 21.1 23.9 --

Dissolved oxygen (mg/L) 37 <.01 .05 .16 .56 2.0 --

Turbidity (NTU) 31 0.08 0.13 0.20 0.46 25 5 (MCL)

Oxidation-reduction (redox) 

potential, SHE (mV)

32 -110 -80 40 80 380 --

Alkalinity as CaCO3 (mg/L) 40 110 140 160 240 290 --
22 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

of 5 NTU with turbidities of 15, 5.8, and 25 NTU, respectively 

(table 14).

Redox (oxidation-reduction) potential is a measure of the 

intensity of oxidizing or reducing conditions within a system such as water. Positive potentials indicate that the water 

is relatively oxidizing, and negative potentials indicate that 

the water is relatively reducing (Hem, 1992). Redox potential (also called Eh) was measured for water from 32 of the 

40 wells sampled for this study. Redox potential relative to 

a standard hydrogen electrode ranged from -110 (well 7) to 

380 (well 18) mV (millivolts), with a median value of 40 mV 

(tables 7 and 14). Some water-quality constituents such as 

arsenic, iron, and selenium are sensitive to the redox environment, and any change to the redox potential in an environment 

potentially could cause these constituents to dissolve into solution from surrounding aquifer material or to precipitate out of 

solution. Both situations eventually could affect the permeability of the aquifer in addition to releasing potentially harmful 

constituents such as arsenic to the formation water.

Dissolved Solids and Major Ions

Dissolved solids are an important indicator of water 

quality and, in uncontaminated ground water, are the result 

of natural dissolution of rocks and minerals. Dissolved solids 

also are an important indicator of the suitability of water for 

drinking, irrigation, and industrial use. The major constituents 

of dissolved solids in ground-water samples from the study 

area are the cations (positively charged ions) calcium, magnesium, sodium, and potassium, and and the anions (negatively 

charged ions) bicarbonate, sulfate, chloride, fluoride, bromide, 

and silica.

Large concentrations of dissolved solids are undesirable 

in water supplies because of objectionable taste in drinking 

water and limitations for industrial uses (American Public 

Health Association and others, 1998). The USEPA has established a 500-mg/L SDWR for dissolved solids in drinking 

water (U.S. Environmental Protection Agency, 2006). Concentrations of dissolved solids from the 40 sampled water-supply 

wells ranged from 130 (wells 24 and 25) to 1,100 mg/L (well 

31), with a median value of 270 mg/L (tables 8 and 15, fig. 5). 

Water from about one-fourth of the wells (1, 2, 3, 5, 9, 12, 

20, 31, 33, 36, and 40) exceeded the 500-mg/L SDWR for 

dissolved solids. The majority of these wells were located in 

Kansas (fig. 6).

The largest dissolved-solids concentrations determined 

during this investigation probably are related to a general 

transition from freshwater to saline water in the Ozark aquifer 

in an east-to-west trend across the study area (Macfarlane and 

Hathaway, 1987; Imes and Davis, 1991; Imes and Emmett, 

1994). This increase in dissolved solids is a vestige of the 

original connate “formation” water (Jorgensen and others, 

1996) and may reach concentrations as large as 10,000 mg/L 

along the western boundary of the study area (Imes and 

Emmett, 1994). This artifact of ancient seawater also is 

evident in a general shift in water type along an east-to-west 

Table 8. Statistical summary and U.S. Environmental Protection Agency (2006) drinking-water standards for dissolved solids and 

major ions in ground water from 40 water-supply wells completed in Ozark aquifer, northwestern Arkansas, southeastern Kansas, 

southwestern Missouri, and northeastern Oklahoma, 2006–07. 

[mg/L, milligrams per liter; --, not applicable; E, estimated; SDWR, Secondary Drinking-Water Regulation; MCL, Maximum Contaminant Level]

Dissolved solids 

or major ion 

(mg/L)

Number of 

samples Minimum

Percentile

Maximum Drinking-water 

25 standard 50 

(median) 75

Dissolved solids 40 130 190 270 510 1,100 500 (SDWR)

Calcium 40 4.5 30 42 53 250 --

Magnesium 40 1.6 14 18 22 78 --

Sodium 40 1.4 9.8 38 100 403 --

Potassium 40 .3 1.6 2.9 5.3 8.6 --

Bicarbonate 40 130 170 200 290 350 --

Sulfate 40 .4 11 16 45 470 250 (SDWR)

Chloride 40 .8 5.0 38 95 490 250 (SDWR)

Fluoride 40 E.07 .26 .48 .94 4.4 4 (MCL),

2 (SDWR)

Bromide 40 E.01 .04 .12 .28 1.3 --

Silica 40 8.6 9.5 9.8 10 12 --
Quality Characteristics of Ground Water 23

trend (fig. 6). Water from most sampled wells in Missouri is a 

calcium bicarbonate or calcium magnesium bicarbonate type 

(fig. 7), whereas water from wells in Kansas transitions to a 

sodium bicarbonate, sodium bicarbonate chloride, or sodium 

chloride type. The approximate dissolved-solids scale included 

in figure 7 was developed from a relation between the summation of major ions in milliequivalents per liter and dissolvedsolids concentrations (fig. 8). Milliequivalents per liter is the 

measure of the concentration of a solute in solution calculated 

by dividing the concentration in milligrams per liter by the 

equivalent weight of the ion.

Chloride is present in natural water, but large concentrations can impart a salty taste to drinking water and may accelerate the corrosion of metals used in water-supply systems. 

The USEPA has established an SDWR of 250 mg/L for chloride in drinking water (U.S. Environmental Protection Agency, 

2006). Chloride concentrations ranged among the sampled 

wells from 0.8 (well 24) to 490 mg/L (well 33), with a median 

concentration of 38 mg/L (tables 8 and 15, fig. 5). Water 

samples from wells 33 and 36 had chloride concentrations 

greater than the 250-mg/L SDWR (fig. 9, table 15). Because 

the chloride ion can comprise a large part of dissolved-solids 

concentrations, particularly in marine connate water, the chloride concentrations in water from sampled wells had a distributional pattern similar to that of dissolved solids (figs. 6 and 

9). The smallest chloride concentrations were found in water 

from wells in the eastern part of the study area, and concentrations progressively increased in a westerly direction.

Sodium and chloride represents a large fraction of the 

dissolved minerals in marine connate water. Because of this, 

sodium concentrations tended to be large in ground-water 

samples with large chloride concentrations (table 15). Sodium 

concentrations ranged from 1.4 (well 24) to 403 mg/L (well 6), 

with a median concentration of 38 mg/L (table 8). USEPA 

has not established an SDWR or MCL for sodium in drinking 

water but has listed a health-based advisory level (HAL) of 

20 mg/L for individuals on a 500 milligrams per day (mg/d) 

restricted sodium diet (U.S. Environmental Protection Agency, 

2006). Water samples from 23 wells had concentrations that 

exceeded this advisory level (table 15). All but 2 (wells 10 and 

11) of the 15 wells sampled in Kansas yielded samples with 

sodium concentrations exceeding 20 mg/L, whereas only three 

wells (wells 16, 17, and 30) located in the upgradient part of 

the study area (Missouri) had sodium concentrations exceeding 20 mg/L (table 15).

Macfarlane and Hathaway (1987) defined the upgradient 

boundary of the transition zone from freshwater to saline as 

the western edge of the Mississippian outcrop belt west of the 

Missouri and Kansas State line. Natural sources of sulfate in 

water include the weathering or dissolution of sulfur-bearing 

Sulfate

Potassium

0.02 2.9

Bromide

0.02 0.12

(5)

Bicarbonate

1.0 200

Sodium

0.12 38

Silica

9.8 0.018

Magnesium 0.02 18

16 0.18 250

Chloride 0.12 38 250

Dissolved solids

10 270 500

Median value

Secondary DrinkingWater Regulation Calcium

0.04 42

Method reporting limit (MRL) 

Fluoride

0.48

(1) 0.12 2.0 4.0

Maximum Contaminant Level

Number of values

less than MRL 

Estimated or reported

value less than MRL

0.01 0.1 1.0 10 100 1,000 10,000

CONCENTRATION, IN MILLIGRAMS PER LITER

Cations Anions

Figure 5. Method reporting limits, sample concentrations and median values, and drinking-water standards for dissolved solids and 

major ions detected in ground water from 40 water-supply wells completed in Ozark aquifer, northwestern Arkansas, southeastern 

Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07. Drinking-water standards established by U.S. Environmental 

Protection Agency (2006).
24 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

Galena Joplin

Carthage Mt Vernon

 Monett

 Cassville

 Aurora

Neosho

Bentonville

Eureka

Springs

Fayetteville Huntsville

Gravette

Baxter Springs

Oswego Columbus

Vinita

Nowata

Claremore

Pryor Jay

Independence

Miami

Lamar

Greenfield

Nevada

Stockton

Osceola

Pittsburg

Arcadia

Parsons

Erie

Chanute

Yates Center

Iola

Fort Scott

MISSOURI

KANSAS

North Fork Spring River

Sac River

Sac River

Osage River

Marmaton River

Neosho River

Pineville

KANSAS

OKLAHOMA

OKLAHOMA

ARKANSAS

ARKANSAS

MISSOURI

Illinois

River

Beaver

Reservoir

Lake Hudson

Grand Lake O' the Cherokees

Oologah Lake

Table Rock Lake

Kings River

River

Spring River

Fall River

River

Verdigris River

Neosho River

Verdigris River

Roaring

Spring River

Stockton Lake

Elk

Empire Lake

Little Osage River

Study area

Study area

9

8

7

6 5

4

3

2

1

40

39

38 37

36

35 34

33

32

31

30

29

28

27

26

25

23 24

22

21 20

19

18

17

16

15

14 13 12

11

10

0 5 10 15 20 MILES

0 5 10 15 20 KILOMETERS

Base from U.S. Geological Survey digital data, 1999, 1:100,000

Universal Transverse Mercator projection

Zone 15

Horizontal coordinate information is referenced to the North American

 Datum of 1983 (NAD 83)

95°45'

45'

37°

38°

30' 15' 95° 45' 30' 15' 94° 45' 93°30'

36°

45'

30'

30'

15'

15'

EXPLANATION

Boundary of study area

Dissolved-solids concentration,

 in milligrams per liter—Numbers

 are map index numbers for water-

 supply wells sampled during 2006−07

0−250

251−500

40 501 or larger

38

35

Figure 6. Distribution of dissolved-solids concentrations in ground water from 40 water-supply wells completed in Ozark aquifer, 

northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07.
Quality Characteristics of Ground Water 25

0 5 10 15 20

600 300 0 300 600

20 15 10 5

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

MILLIEQUIVALENTS PER LITER

APPROXIMATE DISSOLVED-SOLIDS CONCENTRATION,

IN MILLIGRAMS PER LITER

MAP INDEX NUMBER (FIG. 4)

Cations Anions

Kansas wells

Arkansas wells

Oklahoma wells

Missouri wells

EXPLANATION

Chloride

Sulfate

Bicarbonate

Magnesium

Sodium plus

 potassium

Calcium

Figure 7. Major ion composition of ground water from 40 water-supply wells completed in Ozark aquifer, northwestern Arkansas, 

southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–2007.
26 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

minerals, such as pyrite and gypsum, volcanic discharges 

to the atmosphere, and biologic and biochemical processes 

(Hem, 1992). Large concentrations of sulfate in drinking 

water may cause laxative effects. USEPA has established 

an SDWR of 250 mg/L for sulfate in drinking water (U.S. 

Environmental Protection Agency, 2006). Sulfate concentrations ranged from 0.4 (well 39) to 470 mg/L (well 20), with 

a median concentration of 16 mg/L (tables 8 and 15). Water 

samples from wells 20 and 31 had sulfate concentrations 

larger than the 250-mg/L SDWR (fig. 10, table 15). Sulfate 

concentrations generally were largest in samples from wells 

located in the western part of the study area (fig. 10). The 

sulfate measured in well 20 is essentially the same sulfate 

concentration that it exhibited when that well was drilled. No 

other nearby water-supply wells have this problem, but several 

nearby wells do have somewhat elevated sulfate concentrations (Jim Vandike, U.S. Geological Survey, written commun., 

2009). The elevated sulfate concentrations may be caused by 

a deposit a couple of miles to the southeast where there is a 

major mineralized breccia zone that has considerable vertical 

extent and may have breached the confining unit (Jim Vandike, 

U.S. Geological Survey, written commun., 2009). A noticeable 

hydrogen-sulfide odor was evident in well water at the time of 

sampling increased in intensity in the downgradient direction 

(away from recharge areas in Missouri). The most noticeable 

hydrogen-sulfide odor occurred in wells along and west of the 

Kansas State line. 

Fluoride is present in natural water at a concentration 

usually smaller than 1.0 mg/L and is the result of weathering of fluorine-containing minerals such as fluorite or apatite. More advanced animals incorporate fluoride into bone 

and teeth tissues (Hem, 1992). However, excessive fluoride 

concentrations in drinking water can cause dental or skeletal fluorosis, and in response, the USEPA established two 

regulatory levels for fluoride in drinking water—an SDWR 

of 2.0 mg/L and an MCL of 4.0 mg/L (U.S. Environmental 

Protection Agency, 2006). Fluoride concentrations in groundwater samples collected during this investigation generally 

were less than 1.0 mg/L, with a median concentration of 0.48 

mg/L (table 8, fig. 5). However, samples from seven wells had 

fluoride concentrations of 1.0 mg/L or larger, and concentrations ranged from 1.0 (wells 8 and 36) to 4.4 mg/L (well 39) 

(table 15). Fluoride concentrations in samples from wells 33, 

35, 39, and 40 exceeded the 2.0-mg/L SDWR, whereas the 

concentration in the sample from well 39 was the only sample 

concentration to exceed the 4.0-mg/L MCL (fig. 5).

Concentrations of magnesium, potassium, bromide, and 

silica generally were small in water from sampled wells relative to other major ions (fig. 5, table 8). The USEPA has not 

established drinking-water standards for these four ions.

Nutrients

Nutrients, which contain the elements nitrogen and phosphorus, are essential for the growth and reproduction of plants. 

Compounds of nitrogen and phosphorus contained in synthetic 

fertilizers and manure, commonly are applied to cropland 

and some pastures to stimulate plant growth and increase 

crop yields and hay production. Synthetic fertilizers include 

anhydrous ammonia, ammonium nitrate, urea and mono- and 

diammonium phosphates. Other sources of nutrients include 

human waste, nitrogen-containing organic compounds, and 

industrial waste. Recharge water in areas where nutrients are 

applied or disposed on the land surface can leach nutrients and 

infiltrate into the ground-water system and potentially contaminate drinking-water sources. Large concentrations of nutrients 

(particularly nitrates) in drinking water may be physiologically 

damaging to humans. 

Concentrations of nitrite, nitrite plus nitrate, ammonia, total nitrogen, phosphorus, and orthophosphate, were 

determined in ground water from the 40 water-supply wells 

sampled during the investigation described in this report. Generally, nutrient concentrations in water from the 40 wells were 

small (table 16 in the “Supplemental Information” section at 

the back of this report) and always less than drinking-water 

standards.

Nitrite and nitrate are inorganic ions produced during 

various stages of the nitrogen cycle. In oxygenated natural 

water, nitrite typically is oxidized to nitrate (U.S. Environmental Protection Agency, 1986); thus, nitrate will tend to predominate. Nitrite and nitrate usually occur in relatively small 

concentrations in uncontaminated water. Mueller and Helsel 

(1996) estimated a national average background concentration of nitrate in ground water of 2.0 mg/L as nitrogen, which 

indicates that concentrations larger than 2.0 mg/L may result 

from contamination from human activities.

Human health-based regulations have been established 

for nitrate concentrations in drinking water because of the 

potential adverse health effects on infants. Consumption 

of drinking water with nitrate concentrations larger than 

0

200

400

600

800

1,000

1,200

0 10 20 30 40

DISSOLVEDSOLIDS,IN MILLIGRAMSPERLITER

SUMMATIONOF MAJORIONS,IN MILLIEQUIVALENTSPERLITER

Y = 29.5X

R2

= 99.6

Figure 8. Relation between summation of major ions and 

dissolved solids in ground water from 40 water-supply wells 

completed in Ozark aquifer, northwestern Arkansas, southeastern 

Kansas, southwestern Missouri, and northeastern Oklahoma, 

2006–07.
Quality Characteristics of Ground Water 27

Galena Joplin

Carthage Mt Vernon

 Monett

 Cassville

 Aurora

Neosho

Bentonville

Eureka

Springs

Fayetteville Huntsville

Gravette

Baxter Springs

Oswego Columbus

Vinita

Nowata

Claremore

Pryor Jay

Independence

Miami

Lamar

Greenfield

Nevada

Stockton

Osceola

Pittsburg

Arcadia

Parsons

Erie

Chanute

Yates Center

Iola

Fort Scott

MISSOURI

KANSAS

North Fork Spring River

Sac River

Sac River

Osage River

Marmaton River

Neosho River

Pineville

KANSAS

OKLAHOMA

OKLAHOMA

ARKANSAS

ARKANSAS

MISSOURI

Illinois

River

Beaver

Reservoir

Lake Hudson

Grand Lake O' the Cherokees

Oologah Lake

Table Rock Lake

Kings River

River

Spring River

Fall River

River

Verdigris River

Neosho River

Verdigris River

Roaring

Spring River

Stockton Lake

Elk

Empire Lake

Little Osage River

Study area

9

8

7

6 5

4

3

2

1

40

39

38 37

36

35 34

33

32

31

30

29

28

27

26

25

23 24

22

21 20

19

18

17

16

15

14 13 12

11

10

0 5 10 15 20 MILES

0 5 10 15 20 KILOMETERS

95°45'

45'

37°

38°

30' 15' 95° 45' 30' 15' 94° 45' 93°30'

45'

30'

30'

15'

15'

Base from U.S. Geological Survey digital data, 1999, 1:100,000

Universal Transverse Mercator projection

Zone 15

Horizontal coordinate information is referenced to the North American

 Datum of 1983 (NAD 83)

36°

EXPLANATION

Boundary of study area

Chloride concentration, in milligrams

 per liter—Numbers are map index

 numbers for water-supply wells sampled

 during 2006−07

0−50

51−250

36 251 or larger

30

35

Figure 9. Distribution of chloride concentrations in ground water from 40 water-supply wells completed in Ozark aquifer, 

northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07.
28 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

Galena Joplin

Carthage Mt Vernon

 Monett

 Cassville

 Aurora

Neosho

Bentonville

Eureka

Springs

Fayetteville Huntsville

Gravette

Baxter Springs

Oswego Columbus

Vinita

Nowata

Claremore

Pryor Jay

Independence

Miami

Lamar

Greenfield

Nevada

Stockton

Osceola

Pittsburg

Arcadia

Parsons

Erie

Chanute

Yates Center

Iola

Fort Scott

MISSOURI

KANSAS

North Fork Spring River

Sac River

Sac River

Osage River

Marmaton River

Neosho River

Pineville

KANSAS

OKLAHOMA

OKLAHOMA

ARKANSAS

ARKANSAS

MISSOURI

Illinois

River

Beaver

Reservoir

Lake Hudson

Grand Lake O' the Cherokees

Oologah Lake

Table Rock Lake

Kings River

River

Spring River

Fall River

River

Verdigris River

Neosho River

Verdigris River

Roaring

Spring River

Stockton Lake

Elk

Empire Lake

Little Osage River

9

8

7

6 5

4

3

2

1

40

39

38 37

36

35 34

33

32

31

30

29

28

27

26

25

23 24

22

21 20

19

18

17

16

15

14 13 12

11

10

0 5 10 15 20 MILES

0 5 10 15 20 KILOMETERS

95°45'

45'

37°

38°

30' 15' 95° 45' 30' 15' 94° 45' 93°30'

36°

45'

30'

30'

15'

15'

Study area

Base from U.S. Geological Survey digital data, 1999, 1:100,000

Universal Transverse Mercator projection

Zone 15

Horizontal coordinate information is referenced to the North American

 Datum of 1983 (NAD 83)

36°

EXPLANATION

Boundary of study area

Sulfate concentration, in milligrams

 per liter—Numbers are map index

 numbers for water-supply wells sampled

 during 2006−07

0−25

26−250

20 251 or larger

4

6

Figure 10. Distribution of sulfate concentrations in ground water from 40 water-supply wells completed in Ozark aquifer, 

northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07.
Quality Characteristics of Ground Water 29

10 mg/L can cause methemoglobinemia (blue-baby syndrome) 

in infants, a sometimes fatal illness related to the impairment 

of the oxygen-carrying ability of the blood (U.S. Environmental Protection Agency, 1986). Accordingly, an MCL of 10 

mg/L of nitrate as nitrogen has been established by the USEPA 

(U.S. Environmental Protection Agency, 2006).

Nitrite and nitrite plus nitrate (hereinafter referred to as 

nitrate) concentrations generally were less than method reporting limits but were detected in water samples from 9 wells 

(table 16, fig. 11). Nitrate concentrations in water from the 

40 sampled wells ranged from an estimated 0.03 (wells 1, 2, 5, 

and 25) to 2.0 mg/L (well 37), with a median concentration of 

less than 0.06 mg/L (table 9). All nitrate concentrations were 

substantially less than the established MCL of 10 mg/L. Additionally, all determined nitrate concentrations were equal to or 

substantially less than the 2.0-mg/ L national average background concentration reported in Mueller and Helsel (1996).

Total phosphorus and orthophosphate as phosphorus 

typically were present only in small concentrations in water 

from the 40 sampled wells (table 16, fig. 11). Total phosphorus 

was detected only in water from eight wells. Total phosphorus concentrations in water from the 40 wells ranged from an 

estimated 0.002 (wells 3 and 7) to 0.033 mg/L (well 25), with 

a median concentration of less than 0.006 mg/L (table 9). Concentrations of orthophosphate as phosphorus ranged from an 

estimated 0.003 (wells 5, 16, 18, and 34) to 0.015 mg/L (well 

37), with a median concentration of an estimated 0.004 mg/L 

(table 9). Most of the phosphorus in water from the 40 sampled wells was in the form of orthophosphate-phosphorus on 

the basis of similarities in concentrations (table 16).

Water from 90 percent of sampled wells had small 

reportable concentrations of ammonia with a range from an 

estimated 0.01 (well 25) to 0.43 mg/L (well 33) and a median 

concentration of 0.07 mg/L (table 9, fig. 11). Ammonia is the 

dominant nitrogen-containing nutrient in sampled wells in the 

Ozark aquifer and represents most of the total nitrogen as indicated in the similarities between ammonia and total nitrogen 

concentrations (table 16, fig. 11). The dominance of ammonia 

Table 9. Statistical summary and U.S. Environmental Protection Agency (2006) drinking-water standards for nutrients in ground 

water from 40 water-supply wells completed in Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, 

and northeastern Oklahoma, 2006–2007. 

[mg/L, milligrams per liter; E, estimated; --, not applicable; <, less than; MCL, Maximum Contaminant Level]

Nutrient 

(mg/L)

Number of 

samples Minimum

Percentile

Maximum Drinking-water 

standard 25 50 

(median) 75

Nitrite, as nitrogen 40 E.001 <.002 <.002 <.002 .002 1 (MCL)

Nitrite plus nitrate, as nitrogen 40 E.03 <.06 <.06 <.06 2.0 10 (MCL)

Ammonia, as nitrogen 40 E0.01 0.028 0.070 0.19 0.43 --

Total nitrogen 40 E.04 <.06 .09 .23 2.0 --

Phosphorus 40 E.002 <.004 <.006 <.006 .033 --

Orthophosphate, as phosphorus 40 E.003 .004 .004 .005 .015 --

Median value

Method reporting limit (MRL) 

0.004 0.006

(3)

Estimated or reported 0.02 0.07

(5) value less than MRL

0.06 0.09

(7)

Number of values

less than MRL 

0.06

10

Maximum

Contaminant

Level

Median value

less than MRL (35)

0.004 0.006

(36)

Range of reporting limits

0.001 0.01 0.1 1.0 10

CONCENTRATION, IN MILLIGRAMS PER LITER

Orthophosphate,

as phosphorus

Ammonia, as

nitrogen

Phosphorus

Total nitrogen

Nitrite plus nitrate

Figure 11. Method reporting limits, sample concentrations and median values, and drinking-water standards for nutrients detected 

in ground water from 40 water-supply wells completed in Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern 

Missouri, and northeastern Oklahoma, 2006–07. Drinking-water standards established by U.S. Environmental Protection Agency (2006).
30 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

among nitrogen nutrient species is a result of anaerobic conditions within the aquifer. Dissolved oxygen concentrations 

in water from most wells were small (0.56 mg/L at the 75th 

percentile; table 7). Under anaerobic conditions, ammonianitrogen accumulation occurs because of the suppression of 

nitrification (formation of nitrate ion) (Canter, 1996).

The similarity between ammonia and total nitrogen concentrations (fig. 11) indicates that concentrations of organic 

nitrogen in water from Ozark wells are small and that contamination of the Ozark aquifer from surface nitrogen is not 

evident. 

Trace Elements

Trace elements normally occur in natural water in small 

concentrations even though some are naturally abundant. For 

example, aluminum is the one of the most abundant elements 

in the rock of the Earth’s crust; however, it rarely occurs in 

solution in natural water in concentrations greater than a few 

hundred micrograms per liter (Hem, 1992). The occurrence 

in ground water of most of the trace elements listed in table 

13 (in the “Supplemental Information” at the back of this 

report) typically results from natural physical and chemical 

processes. Physical processes include those associated with 

origin and mineral composition, ground-water flow paths, and 

depositional characteristics of sediment in the aquifer. Chemical processes include the interaction of water, oxygen, carbon 

dioxide, and other acidic components that cause the chemical 

breakdown or dissolution of minerals containing trace elements (Brickler and Jones, 1995). Generally, the occurrence 

and chemical speciation of trace elements in ground water are 

determined by (1) hydrogen ion availability (defined by pH); 

(2) the presence and concentrations of inorganic ligands such 

as carbonate, sulfate, sulfide, and chloride; (3) the presence 

and concentrations of organic complexing agents (primarily 

humic and fulvic acids); (4) free electron availability (redox 

potential); and (5) the ionic strength (specific conductance) 

and cation distribution of the water (Allard, 1995).

Concentrations of 24 trace elements (table 13) were 

determined in water from wells sampled during this investigation. Trace elements were of particular concern because the 

historic use of the Tri-State Mining District for production of 

lead and zinc ores provided the opportunity for water to be 

contaminated by trace elements associated with these ores. 

Lead and zinc were the most economically important trace 

elements associated with the minerals mined in the Tri-State 

District (Pope, 2005).

Most trace elements in ground water analyzed during this 

investigation were present in concentrations less than waterquality standards. In fact, many trace constituents frequently 

were not detected or were detected in small concentrations 

(table 17, fig. 12). Seventeen trace elements (antimony, 

arsenic, beryllium, cadmium, chromium, cobalt, copper, lead, 

mercury, molybdenum, nickel, selenium, silver, thallium, 

uranium, vanadium, and zinc) had median concentrations less 

than 1.0 μg/L and were not detected in about 70 percent of the 

samples (tables 10 and 17, fig. 12). Silver was not detected 

in any of the wells. Six constituents had median concentrations greater than 1.0 μg/L—barium, boron, iron, lithium, 

manganese, and strontium. Additionally, nine trace elements 

had a maximum concentration greater than 5.0 μg/L—barium, 

boron, iron, lithium, manganese, molybdenum, strontium, 

and zinc. Iron, lead, and manganese were the only trace 

elements found in concentrations that exceeded USEPA 

drinking-water criteria. 

Iron concentrations in water from sampled wells ranged 

from an estimated 3.0 to 3,200 μg/L, with a median value of 

32 μg/L (table 10). Iron is essential to the growth of plants and 

animals, but when present in large concentrations, precipitates 

of red oxyhydroxide can form and cause staining of laundry or plumbing fixtures (Hem, 1992). Therefore, iron is an 

undesirable impurity in water used for domestic or industrial 

purposes. The USEPA established an SDWR of 300 μg/L 

for iron in drinking water (U.S. Environmental Protection 

Agency, 2006). Water from wells 5, 20, 21, and 31 exceeded 

the SDWR with iron concentrations of 560, 3,200, 1,800, and 

3,000 μg/L, respectively (table 17).

Lead was not detected in water from most wells. Where 

it was detected, it was present at concentrations less than 

1.0 μg/L (table 17). The USEPA established two standards 

for lead in drinking water—an Action Level (AL) of 15 μg/L 

and a Maximum Contaminant Level Goal (MCLG) of 0 μg/L. 

An Action Level is defined as, “...the concentration of a 

contaminant which, if exceeded, triggers treatment or other 

requirements which a water system must follow...” (U.S. 

Environmental Protection Agency, 2006). An MCLG is a nonenforceable goal for a contaminant set at a level at which no 

known or anticipated adverse health effects are expected and 

which allows a margin of safety (U.S. Environmental Protection Agency, 2006). Concentrations of lead were substantially 

smaller than the AL. Twelve wells (2, 3, 4, 6, 7, 10, 13, 14, 18, 

22, 37, and 39) had measurable lead concentrations and, thus, 

exceeded the MCLG (table 17).

Manganese concentrations ranged from 0.32 to 95 μg/L 

and had a median value of 1.8 μg/L (table 10). Manganese is 

an objectionable impurity in water supplies because of staining from black manganese oxide deposits (Hem, 1992). The 

USEPA established an SDWR of 50 μg/L for manganese in 

drinking water (U.S. Environmental Protection Agency, 2006). 

Water from wells 20 and 21 exceeded the SDWR with manganese concentrations of 95 and 68 μg/L (table 17), respectively.

Potential Effect of Mining on Water 

Quality

One ground-water-quality concern in the study area is 

that past lead and zinc mining in the Tri-State Mining District may be a source of trace-element contamination for the 

Ozark aquifer. As previously discussed in the “Geology” and 

“Geohydrology” sections of this report, mining was conducted 
Potential Effect of Mining on Water Quality 31

in some of the Mississippian-age rock formations that compose the Springfield Plateau aquifer (figs. 1 and 3; table 1). 

The Springfield Plateau aquifer is mostly unconfined in the 

study area and receives direct precipitation recharge. Therefore, water in the Springfield Plateau aquifer might well be 

a younger age (time since recharge) relative to water in the 

underlying, confined Ozark aquifer in the study area, which 

primarily occurs as a result of recharge and lateral migration 

from unconfined areas in the Ozark Plateaus east of the study 

area (fig. 1). The presence of younger water and elevated 

concentrations of trace elements such as iron and lead in the 

Ozark aquifer may be indicative of movement of Springfield 

Plateau aquifer water into the Ozark aquifer and the possibility of surface contamination or may be from poor quality 

mine water.

Water from a water-supply well in Galena, Kansas 

(well 13, fig. 4), does show younger water characteristics 

relative to other sampled Ozark aquifer wells as evidenced by 

isotope analysis. Tritium radioactivity (in picocuries per liter, 

pCi/L) was largest in water from well 13 among the 11 wells 

sampled for tritium (table 17). The 4.7 pCi/L tritium concentration in water from well 13 was about five times larger than 

the second largest concentration (well 6, 1.0 pCiL).

The 4.7 pCi/L tritium concentration determined in water 

from well 13 falls within the range (2.6 to 12.8 pCi/L) indicating ground water containing a mixture of submodern and 

recent (since 1952) recharge (Clark and Fritz, 1997, p. 185). 

Because tritium concentrations in water from the other 10 

wells sampled in the Ozark aquifer were relatively small and 

within the range (less than 2.6 pCi/L) indicating recharge prior 

to 1952, it is probable that the mixed recharge water from 

well 13 is the result of a downward movement of younger 

water from the Springfield Plateau aquifer. This downward 

movement could occur through cracks or fissures in the Ozark 

confining unit that separates the Springfield Plateau and 

Ozark aquifers (fig. 3), water-supply wells open to both the 

Springfield Plateau and Ozark aquifers, poorly constructed or 

abandoned wells, or as a result of historic lead-and-zinc mining activities (exploratory drill holes or water-supply wells). 

Further evidence of mixed recharge water is indicated in the 

14C results for well 13 (table 17). Water from well 13 had the 

largest percentage of modern 14C (0.13 percent) of any of the 

Ozark aquifer wells sampled.

0.001 0.01 0.1 1.0 10 100 1,000 10,000

CONCENTRATION, IN MICROGRAMS PER LITER

Aluminum

Boron

Beryllium

Barium

Arsenic

Antimony

Molybdenum

Mercury

Manganese

Lithium

Lead 

 Iron

Copper

Cobalt

Chromium

Cadmium

Zinc

Vanadium

Uranium, natural

Thallium

Strontium

Silver

Selenium

Nickel

1.6

0.06 0.20

0.12

0.40

0.06 8.0

0.04 0.12

0.04 1.2

0.40 6.0

0.08 0.12

1.0

0.20

0.01 0.40

0.12 0.06

0.08

0.08 1.0

0.80

0.04

0.04

0.04 0.10 0.60

32

1.8

0.44

0.06

0.13

0.63

(23)

(1)

(37)

(0)

(25)

(34)

(33)

(17)

(31)

(0)

(28)

(3)

(33)

(39)

(23)

(36)

(0)

(1)

(11)

(33)

(2)

(37)

(0)

(40)

6.0

50

10

2,000

4.0

5.0

100

1,000

300

0

50

2.0

50

100

2.0

30

5,000

Method Reporting Limit (MRL)

Range of reporting limits

Maximum Contaminant Level

Secondary Drinking-Water Regulation

Number of values less than MRL

Median value

Median value less than MRL

87

57

51

320

Estimated or reported value less than MRL

Figure 12. Method reporting limits, sample concentrations and median values, and drinking-water standards for trace elements 

detected in ground water from 40 water-supply wells completed in Ozark aquifer, northeastern Arkansas, southeastern Kansas, 

southwestern Missouri, and northeastern Oklahoma, 2006–07. Drinking-water standards established by U.S. Environmental Protection 

Agency (2006).
32 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

Table 10. Statistical summary and U.S. Environmental Protection Agency (2006) drinking-water standards for trace elements in 

ground water from 40 water-supply wells completed in Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern 

Missouri, and northeastern Oklahoma, 2006–07. 

[μg/L, micrograms per liter; E, estimated; --, not applicable; <, less than; SDWR, Secondary Drinking-Water Regulation; MCL, Maximum Contaminant 

Level; AL, Action Level; MCLG, Maximum Contaminant Level Goal]

Trace element 

(μg/L)

Number of 

samples Minimum

Percentile

Maximum Drinking-water 

25 50 (median) 75 standard

Aluminum 40 E0.8 1.0 <1.6 <1.6 8.9 50 to 200 (SDWR)

Antimony 40 E.03 <.06 <.06 <.20 <.10 6 (MCL)

Arsenic 40 E.10 <.12 <.12 .38 4.9 10 (MCL)

Barium 40 4.2 21 57 102 280 2,000 (MCL)

Beryllium 40 E.03 <.06 <.06 <.06 <.06 4 (MCL)

Boron 40 E6.0 27 87 220 1,400 --

Cadmium 40 E.03 <.04 <.04 <.04 <.40 5 (MCL)

Chromium 40 E.02 .07 <.12 <.12 .45 100 (MCL)

Cobalt 40 E.02 <.04 <.04 <.04 .75 --

Copper 40 E.21 <.40 <.40 <.40 1.6 1,000 (SDWR)

Iron 40 E3.0 13 32 78 3,200 300 (SDWR)

15 (AL)

Lead 40 E.04 .09 <.12 <.12 <1.2 0 (MCLG)

Lithium 40 E.86 16 51 94 240 --

Manganese 40 .31 1.2 1.8 2.7 95 50 (SDWR)

Mercury 40 E.006 <.01 <.01 <.01 .01 2 (MCL)

Molybdenum 40 E.09 .38 .44 1.8 13 --

Nickel 40 E.03 .04 .06 .11 2.4 --

Selenium 40 E.04 <.08 <.08 <.08 .90 50 (MCL)

Silver 39 <.1 <.1 <.1 <.2 <1.0 100 (SDWR)

Strontium 40 47 150 320 950 1,700 --

Thallium 40 E.02 <.04 <.04 <.04 <.40 2 (MCL)

Uranium 40 E.03 .05 .13 .34 4.5 30 (MCL)

Vanadium 40 E.02 <.04 .04 <.10 .23 --

Zinc 40 E.30 .50 .63 1.3 130 5,000 (SDWR)
Potential Effect of Mining on Water Quality 33

Macfarlane and Hathaway (1987) noted larger concentrations of sulfate in water from the Ozark aquifer in the Tri-State 

mining areas and speculated that the additional sulfate could 

have come from oxidized sulfides in the overlying Springfield 

Plateau aquifer. Well numbers 20 and 31 had elevated concentrations of sulfate (table 15).

Galena, Kansas, was the center of lead-and-zinc mining in southeastern Kansas beginning about 1876 and lasting 

until about 1925 when major production activities shifted to 

the Baxter Springs (fig. 4) area (Gibson, 1972). Nearly all 

mining in the Tri-State District used room-and-pillar methods in geologic formations of the Springfield Plateau aquifer, 

and once the mines were abandoned, these rooms filled with 

ground water. Previous investigations have determined that 

mine-associated water had large specific conductance and 

sulfate concentrations and is contaminated with sulfate and 

trace elements and such as cadmium, lead, zinc, and others 

(Haworth and others, 1904; Bailey, 1911; Barks, 1977; Playton 

and others, 1980; Spruill, 1987; Parkhurst, 1988; and DeHay, 

2003). Therefore, the occurrence of these trace elements and 

sulfate in water from the Ozark aquifer may be an indication 

of the movement of contaminated water through one or a combination of the previously mentioned flow paths.

Water from well 13 also had large concentrations of copper (0.74 μg/L), lead (0.20 μg/L), and zinc (54 μg/L) relative 

to water from most of the other sampled Ozark aquifer wells. 

In fact, the concentrations of lead and zinc in water from 

well 13 were the second largest concentrations of lead and 

zinc among the 40 wells sampled (table 17). These results, 

in conjunction with the mixed-age recharge characteristics 

for well 13, indicate the possibility that contaminated water 

in the Springfield Plateau aquifer has migrated downward to 

the Ozark aquifer and potentially compromised the use of the 

aquifer for public supply, at least on a local scale in the mined 

areas. The water chemistry from well 20 (table 15) also may 

be affected by mining activities as indicated by large calcium 

and sulfate concentrations. 

Table 11. Physical property and chemical-constituent determinations that exceed U.S. Environmental Protection Agency 

(2006) drinking-water standards in ground water from 40 water-supply wells completed in Ozark aquifer, northwestern Arkansas, 

southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07. 

[NTU, nephelometric turbidity units; MCL, Maximum Contaminant Level; mg/L, milligrams per liter; SDWR, Secondary Drinking-Water Regulation; μg/L, 

micrograms per liter; MCLG, Maximum Contaminant Level Goal]

Property or constituent

Total number of wells that exceed drinkingwater standards

(map index number, fig. 4)

Drinking-water standard

Physical property

Turbidity 3 5.0 NTU (MCL)

(1, 5, 9)

Dissolved solids and major ions

Dissolved solids 11 500 mg/L (SDWR)

(1, 2, 3, 5, 9, 12, 20, 31, 33, 36, 40)

Sulfate 2 250 mg/L (SDWR)

(20, 31)

Chloride 2 250 mg/L (SDWR)

(33, 36)

Fluoride 1 4 mg/L (MCL)

(39)

3 2 mg/L (SDWR)

(33, 35, 40)

Trace elements

Iron 4 300 μg/L (SDWR)

(5, 20, 21, 31)

Lead 12 0 μg/L (MCLG)

(2, 3, 4, 6, 7, 10, 13, 14, 18, 22, 37, 39)

Manganese 2 50 μg/L (SDWR)

(20, 21)
34 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

Summary of Regulatory Exceedances

The water from wells sampled during this investigation 

exceeded enforceable MCL standards in only four measurements or determinations (table 11). USEPA set an MCL of 5 

NTU (nephelometric turbidity units) for turbidity in drinking 

water. Water from wells 1, 5, and 9 exceeded this standard 

with turbidities of 15, 5.8, and 25 NTU, respectively (table 

14 in the “Supplemental Information” section at the back of 

this report). Additionally, water from well 39 exceeded the 

4.0-mg/L MCL for fluoride with a concentration of 4.4 mg/L 

(table 15).

Nonenforceable SDWR and MCLG drinking-water 

standards were exceeded in water from sampled wells in a 

total of 36 water-quality constituent determinations (table 11). 

Concentrations of dissolved solids in water from wells 1, 2, 3, 

5, 9, 12, 20, 31, 33, 36, and 40 exceeded the 500-mg/L SDWR 

with concentrations that ranged from 510 to 1,100 mg/L 

(table 15). Concentrations of sulfate in water from wells 20 

and 31 exceeded the 250-mg/L SDWR with concentrations 

of 470 and 440 mg/L, respectively, and concentrations of 

chloride in water from well 33 and 36 exceeded the 250-mg/L 

SDWR with concentrations of 490 and 350 mg/L, respectively 

(table 15). An SDWR of 2.0 mg/L for fluoride was exceeded 

in water from wells 33, 35, and 40 with concentrations of 2.4, 

3.9, and 2.4 mg/L, respectively (table 15).

Three trace elements (iron, lead, and manganese) 

exceeded nonenforceable drinking-water-quality standards 

in water from some wells (tables 11 and 17). Concentrations 

of iron were larger than the SDWR of 300 μg/L in wells 5, 

20, 21, and 31 with concentrations that ranged from 560 to 

3,200 μg/L. Lead usually was not detected in the water from 

sampled wells but was detected in concentrations that ranged 

from 0.04 (estimate) to 0.32 μg/L in 12 wells (2, 3, 4, 6, 7, 

10, 13, 14, 18, 22, 37, and 39), which exceeded the MCLG of 

0 μg/L. Concentrations of manganese exceeded the 50-μg/L 

SDWR in water from wells 20 and 21 with concentrations of 

95 and 68 μg/L, respectively.

Flow-Path Evolution

The previous discussion of spatial distribution of waterquality characteristics in this report indicates a general evolution in water quality for some major ions in an east-to-west 

direction across the study area. In an attempt to examine this 

evolution in more detail, 11 of the 40 selected water-supply 

wells were evaluated on the basis of their location along two 

generalized ground-water flow paths. Five wells (26, 25, 23, 

13, and 12; fig. 13) were selected to define `water-quality evolution along a westerly trending ground-water flow path originating from a potentiometric high in Missouri, and six wells 

(24, 21, 19, 17, 6, and 2; fig. 13) were selected to represent a 

northwesterly trending flow path originating from the same 

general potentiometric high in Missouri as the westerly trending flow path. The westerly trending flow path tracks past the 

major pumping center at Joplin, Missouri, and subsequently 

through Galena, Kansas (well 13; fig. 4). The northwesterly 

flow path tracks through the major pumping center at Pittsburg, Kansas (well 6; fig. 4).

Analyses of stable isotopes in water have been used to 

identify source, age, and mixing characteristics of ground 

water (Clark and Fritz, 1997). Stable isotopes are isotopes 

that do not radioactively decay. In nature, isotopic variations 

occur because substances (such as water, minerals, and gases) 

preferentially concentrate one isotope over another or because 

organisms can metabolize one isotope more efficiently than 

another. Natural isotope variations, therefore, can arise from 

numerous common chemical and physical processes, such 

as cooling of hydrothermal fluids during mineral deposition, 

the evaporation or condensation of water, mixing of two or 

more sources of water, or the metabolic activity of organisms 

(Seal, 2008).

The stable isotopes with relatively low atomic mass, such 

as carbon, hydrogen, oxygen, and sulfur, are the most biogeochemically active elements and display wide ranges in isotopic 

abundance. However, other elements with relatively large 

atomic masses, such as strontium, also have isotopic ratios 

that may be useful indicators of water-rock interactions and as 

tracers for ground-water movement (Clark and Fritz, 1997).

Water from all 11 flow-path wells was collected and 

analyzed for selected stable isotopes (table 13 in the “Supplemental Information” section at the back of this report). Results 

of analyses of stable isotopes are presented in table 17 at the 

back of this report. Analytical results are presented as a ratio 

of the two most abundant isotopes of individual elements relative to the isotopic ratio of a known standard and expressed in 

delta (δ) notation in per thousand parts or permil (‰) of the 

heavier isotope (for example, δ18O). Isotope reference standards are the Vienna Standard Mean Ocean Water (VSMOW) 

for hydrogen (2H/1H) and oxygen (18O/16O) isotope ratios, the 

Vienna Pee Dee Belemnite (VPDB) for carbon (13C/12C), and 

the Cañon Diablo Troilite (CDT) for sulfur isotopes (34S/32S). 

The isotopic ratio of strontium-87 (87Sr) to strontium-86 (86Sr) 

is an absolute ratio in sampled water. A positive δ value means 

that the sample contains more of the heavy isotope than the 

standard; a negative δ value means that the sample contains 

less of the heavy isotope than the standard. For example, a 

δ 18O value of -7.0 permil means that there are 7 parts per 

thousand or 0.7 percent less 18O in the sample relative to the 

standard (Kendall and Caldwell, 1998).

The origin of most fresh ground water is atmospheric 

precipitation that infiltrated where it fell or accumulated in 

streams and lakes and then seeped into the ground (Bouwer, 

1978). It has been estimated that for the contiguous United 

States about 25 percent of the precipitation that falls becomes 

ground water (Nace, 1960). Ground water that was recently of 

atmospheric origin is referred to as meteoric water, whereas 

water that has been in the subsurface since sediment deposition is called connate water (Bouwer, 1978). Meteoric and 

connate water may have substantially different isotopic sig-
Potential Effect of Mining on Water Quality 35

1200

850

800

600

700

650

950

1050 1100

1150

1200

1100

1200

1300

850 900

800

950 1000

900

650

750

600

500 450

850

900

900

650

700

600 550

500

450

400

750

700

1250

1000

800

800750

700 650600

900

800

750

700650

650

700

650

650

700

700

1000

1050

1150

1100

1050

1250

1050

1000

900

850

850

2

12

13

13

23

25

26

6

17

19

21

24

1100

1050

1000

950

900

850

1150

1100

850

650

750

0 5 10 15 20 MILES

0 5 10 15 20 KILOMETERS EXPLANATION

Potentiometric contour–Shows altitude at which water

 level would stand in tightly cased wells. Contour

 interval is 50 feet. Dashed where approximately

 located. Datum is North American Vertical Datum

 of 1929 (NAVD 29)

Potentiometric depression contour–Shows altitude

 at which water level would stand in tightly cased wells. 

 Contour interval is 50 feet. Datum is North American

 Vertical Datum of 1929 (NAVD 29)

Base from U.S. Geological Survey digital data, 1999, 1:100,000

Universial Transverse Mercator projection

Zone 15

Horizontal coordinate information is referenced to the North American

 Datum of 1983 (NAD 83)

Potentiometric contours modified from Gillip and others, 2008

95°45'

45'

37°

38°

30' 15' 95° 45' 30' 15' 94° 45' 93°30'

36°

45'

30'

30'

15'

15'

Study area

MISSOURI

Beaver

Reservoir

Kings River

Illinois

Lake Hudson

Oologah Lake

Table Rock Lake

River

Verdigris River

Neosho River

Roaring

Spring River

Stockton Lake

Elk

KANSAS

Osage River

Marmaton River

KANSAS

River

Study area

OKLAHOMA

MISSOURI

ARKANSAS

River

Ground-water flow path and water-supply well 

 with map index number

Calcium

Sodium and potassium

Magnesium

Bicarbonate

Chloride

Sulfate

Neosho River

Grand Lake O' the Cherokees

Sac River

Little Osage River

MILLIEQUIVALENTS PER LITER

MAP NUMBER 2

6

17

19

21

24

Mg Na+K Ca HCO3 Cl SO4

Northwesterly flow-path wells − Stiff diagrams

6 5 4 3 2 1 0 1 2 3 4 5 6

MAP NUMBER

Westerly flow-path wells − Stiff diagrams

MILLIEQUIVALENTS PER LITER

6 5 4 3 2 1 0 1 2 3 4 5 6

12

13

23

25

26

Mg

Mg

Na+K

Na+K

Ca

Ca

HCO3

HCO3

Cl

Cl

SO4

SO4

Northwesterly flow path

Westerly flow path

Figure 13. Potentiometric surface of Ozark aquifer, spring 2006, and water-supply wells completed in Ozark aquifer 

delineating two ground-water flow paths, and stiff diagrams showing results of water-quality analyses, fall 2006, and 

identification of water types.
36 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

natures owning to the climate, temperature, and geography in 

which the water was precipitated (Kendall and Coplen, 2001).

Results of stable isotope analyses of ground water from 

11 flow-path wells seem to indicate that water in the Ozark 

aquifer is of post-Pleistocene meteoric origin. The relation 

between δ18O and δ2H isotopes in water from the flow-path 

wells is similar to the Global Meteoric Water Line (GMWL) 

developed by Craig (1961) from worldwide fresh surface 

water (fig. 14A). A waterline is an equation for a relation 

between hydrogen and oxygen isotope ratios in natural terrestrial water that is expressed as a worldwide average. Craig’s 

line, in reality, is an average of many local and regional 

meteoric waterlines, which differ from the global line due to 

varying climatic and geographic characteristics (Clark and 

Fritz, 1997). The relation between δ18O and δ2H among the 

flow-path wells also is similar to the global precipitation relation developed by Rozanski and others (1993) using weighted 

mean annual precipitation values from monitoring stations in 

the International Atomic Energy Agency’s global network for 

isotopes in precipitation (fig. 14B). The global precipitation 

waterline of Rozanski and others (1993) consisted of a later 

refinement of the GMWL originally presented by Craig 

(1961). If ground-water δ18O and δ2H values plot near the 

global precipitation waterline, the water is likely of meteoric 

origin (that is, derived from precipitation without subsequent 

modification). If the values do not plot along a waterline, the 

water has been affected by some physical or chemical process 

prior to recharge or during the movement of the ground water 

through the aquifer (Harvey, 2001).

Further evidence of a meteoric source for water in the 

Ozark aquifer comes from a comparison of δ18O results from 

the 11 flow-path wells to a relation presented by Kendall 

and Coplen (2001). Kendall and Coplen (2001) developed 

a relation between the latitude (in degrees North) of 391 

sampling sites and δ18O-isotope values in river water of the 

United States. Kendall and Coplen (2001) used river water as 

a surrogate for isotopic characteristics of local and regional 

precipitation. They further segregated the sampling sites into 

eastern and western sites with the 97th meridian as the dividing line and developed separate latitude/ δ18O relations for 

each half of the United States. All Ozark aquifer flow-path 

wells are located east of the 97th meridian. Average latitudes 

were calculated for wells located along both the westerly and 

northwesterly flow paths, plotted in relation to the average 

δ18O values for each flow path, and displayed on a graph of the 

Kendall and Coplen (2001) relation (fig. 15). Ozark aquifer results are similar to Kendall and Coplen (2001) results, 

which indicate that water from the flow-path wells is of meteoric origin. 

The chemistry and isotopes of carbon in ground water 

provide insight in understanding ground-water quality, fate of 

contaminants, and interpretation of ground-water age (Clark 

-12 -10 -8 -6 -4 -2 0

Westerly flow-path well

Westerly flow-path well

Northwesterly

flow-path well

Northwesterly

flow-path well

 δ2H=8.13δ18O+10.8

 δ2H=8.0δ18O+10

 δ18O, IN PERMIL

δ2H, IN PERMIL -50

-48

-46

-44

-42

-40

-38

-36

-34

-32

-30

-50

-48

-46

-44

-42

-40

-38

-36

-34

-32

-30

A.

B.

Global Meteoric Water

Line, Craig (1961)

Global precipitation waterline,

Rozanski and others (1993)

Figure 14. Relation between δ18O and δ2H stable isotopes in 

ground water from 11 flow-path wells completed in Ozark aquifer 

of southeastern Kansas and southwestern Missouri, 2006.

-10

-8

-9

-7

-6

-5

-3

-4

-2

-1

0

25 30 35 40 45 50

LATITUDE, IN DEGREES NORTH

Y=-0.42x+9.39

Kendall and Coplen (2001) relation

 δ18O, IN PERMIL

Westerly flow-path wells

Northwesterly

flow-path wells

Location of wells shown in figure 13

Figure 15. Relation of sampling-site latitudes and δ18O isotope 

values from 391 river-water sampling sites in eastern United 

States (Kendall and Coplen, 2001) to average latitudes and δ18O 

isotope values in ground water from 11 flow-path wells completed 

in Ozark aquifer of southeastern Kansas and southwestern 

Missouri, 2006.
Potential Effect of Mining on Water Quality 37

and Fritz, 1997). Carbon may enter the ground-water system 

as carbon dioxide (CO2) dissolved in precipitation or picked 

up in the soil profile as dissolved inorganic carbon (DIC) 

through infiltration. CO2 can be converted to organic carbon 

through the process of plant photosynthesis and subsequently 

transported from the unsaturated zone in recharge areas to the 

water table and confined aquifer systems in the form of dissolved organic carbon (DOC). The stable carbon-isotope ratio 

13C/12C (δ13C) and the radionuclide 14C were determined on the 

DIC component of ground water collected from the 11 flowpath wells sampled during the investigation described in this 

report.

The δ 13C values for the westerly flow-path wells ranged 

from -6.95 (well 23) to -8.85 permil (well 26) and from -7.14 

(well 19) to -9.71 permil (well 21) for the northwesterly flowpath wells (fig. 13, table 17). All of these values are within the 

expected range for ground-water DIC (Clark and Fritz, 1997). 

These values probably are affected by the dolomite (calcium 

magnesium carbonate) makeup of the Ozark aquifer system. Soil CO2 for the ecosystem overlying the Ozark aquifer 

generally would have δ 13C values of about -23 permil (Clark 

and Fritz, 1997), but as infiltrating water dissolves CO2 and 

some of it hydrates and dissociates into bicarbonate (HCO3

-

) 

and carbonate (CO3

2-), different isotope-fractionation factors 

develop. As recharge water moves through the soil profile and 

into the aquifer system, it encounters carbonate minerals (calcite and dolomite) enriched with 13C (larger, less negative δ 13C 

values) close to the reference VPDB value of about 0 permil. 

Recharge water subsequently dissolves carbonate minerals, 

which provides a diluting (enriching) effect on δ 13C values. 

The generally -7 to -9 permil δ 13C values determined in water 

DIC from the flow-path wells indicate that the Ozark aquifer 

is reacting as a “closed” system. Within this system, δ13C 

evolution is the result of dilution from the more 13C-enriched 

carbonate minerals common in the aquifer formations (table 1) 

and not as an “open” system receiving continual inputs, relative to the flow path, from the large reservoir of DIC in the 

unsaturated zone with reduced 13C composition.

Analytical results of DIC 14C in water from the 11 flowpath wells generally showed an east-to-west downward trend 

in 14C activity (fig. 16) along the two flow paths. Along the 

westerly flow path, the downward trend was interrupted by 

a spike in 14C in water from well 13. This particular activity 

value was discussed previously in the “Spatial Distribution” 

section of this report and probably is the result of downward 

leakage of newer water through the confining unit in the mined 

areas in and around Galena, Kansas. With the exception of the 

small 14C activity at well 24 (the first well in the northwesterly 

flow path sequence), a downward trend is evident in water 

from wells along the northwesterly flow path. The reason for 

the small 14C activity in water from well 24 is not known.

Downward trends in 14C activity and, therefore, increasing age in ground water along the two flow paths would 

indicate the occurrence of one or more of three processes: 

(1) ground water is aging as a result of residence time along 

the flow path, (2) 14C is being lost through exchange with the 

mineral matrix of the aquifer formations, or (3) 14C activity is 

being diluted by dissolution of DIC “dead” carbon (carbon so 

old that it has lost all 14C activity) from the carbonate formations through which it flows. The possibility that 14C results 

determined during this investigation provide reliable age 

estimates for recharged water probably is not a viable conclusion. The 14C pmC values determined from the sampled wells 

indicate age estimates of at least 25,000 years BP (before present) (Stuiver and Polach, 1977). These estimates probably are 

erroneously old on the basis of previously presented information. The δ 2H/ δ 18O relation developed for the flow-path wells 

indicated an isotopic signature similar to the modern GMWL 

(Craig, 1961) and the global precipitation relation developed 

by Rozanski and others (1993) (fig. 14). Water with an age in 

excess of 25,000 years BP would place it at the maximum of 

the last major glacial period in North America (the Wisconsin), 

and the δ 2H/ δ 18O-relational signature of precipitation (and 

ultimately recharge water) during this much colder climate 

would be substantially different from the current GMWL 

because isotopic fractionation is, in part, thermally driven. 

Additionally, δ 13C values for DIC in water from the flow-path 

wells indicated a mixture of DIC from recharge water and DIC 

containing “dead” carbon from carbonate minerals. The downward trend in 14C activity indicated in figure 16 probably is 

the result of a loss of 14C through a matrix exchange between 

the DIC in recharged water and the carbonate minerals in the 

aquifer matrix and matrix diffusion of 14C into dead-end pores 

of the aquifer material (Maloszewski and Zuber, 1991), and a 

simple dilution by non-14C-containing DIC from dissolution 

0

2

4

6

8

10

12

14

16

18

-20 -10 0 10 20 30 40 50 60

CARBON-14 (14c), IN PERCENT MODERN

DISTANCE FROM KANSAS-MISSOURI STATE LINE, IN MILES

EXPLANATION

Kansas Missouri State line

Westerly flow path

Northwesterly flow path

12 2

13

13

17

17

6

19

23

25

21

24

26

Northwesterly flow-path well

 and map index number

Westerly flow-path well and

 map index number

Location of wells shown in figure 13

Figure 16. Carbon-14 (14C) activity in ground water from 11 flowpath wells completed in Ozark aquifer of southeastern Kansas and 

southwestern Missouri, 2006.
38 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

of the carbonate minerals deposited hundreds of millions of 

years ago.

The result of 14C data is ambiguous at best, at least within 

the scope of the reconnaissance investigation described in this 

report. The small detections of tritium in water from the flowpath wells (table 17) coupled with other stable-isotope data 

indicate that ground water along the two selected flow paths 

is more than about 60 years old but substantially less than the 

25,000 years BP as indicated by the 14C data. The spikes in 14C 

and 3H in well 13 indicated that there was possible leakage 

of younger ground water into the lower Ozark aquifer. This 

may be caused by cracks and fissures in the confining unit that 

separates the upper and lower parts of the aquifer.

Strontium (Sr) is a fairly common element in natural 

water as a divalent cation with reaction chemistry similar 

to that of calcium and can replace calcium or potassium in 

some minerals. The minerals strontianite (strontium carbonate) and celesite (strontium sulfate) are common in sediment. 

The strontium-to-calcium ratio in most limestone is less than 

1:1,000, although fossils in the limestone tend to be enriched 

in strontium. The strontium concentration in most natural 

water does not approach the solubility limit of either strontianite or celesite (Hem, 1992). In ground-water systems, the 

concentration of strontium is dependent upon the initial concentration in recharge water but, more importantly, the contact 

time (flow-path residence time) with the mineral matrix and 

composition of the formations through which the water flows. 

Therefore, along a ground-water flow path in a carbonatedominated system, increasing concentrations of strontium 

would be expected as Sr+2 trends toward geochemical equilibration with strontium minerals. Strontium concentrations in 

water from wells along the westerly and northwesterly flow 

paths in the Ozark aquifer generally increase with distance 

from recharge areas in the east (fig. 17).

Strontium has four stable, naturally occurring isotopes— 84Sr (0.56 percent), 86Sr (9.86 percent), 87Sr (7.00 percent), and 88Sr (82.58 percent) (Kendall and others, 1995). The isotope 

ratio 87Sr/86Sr can be a useful indicator of water-rock interaction, as a tracer for ground-water movement, and in determining the origin of salinity (Clark and Fritz, 1997). The isotopic 

composition of strontium in ground water depends on the 

chemistry of recharge, host rock geochemistry and water-rock 

interactions in ground-water systems, the residence time of 

ground water in the aquifer, and the mixing of different ground 

water (Ma and Liu, 1999). The 87Sr/86Sr ratio in minerals and 

rock ranges from about 0.7 to greater than 4.0 (Faure and 

Powell, 1972). In water from wells of the two selected flow 

paths in the Ozark aquifer, 87Sr/86Sr ratios ranged from 0.71061 

(well 25) to 0.71532 (well 12) for the westerly flow path and 

0.71002 (well 21) to 0.71424 (well 2) for the northwesterly 

flow path (table 17). Generally, however, strontium-isotopic 

ratios increased in a downgradient (increasing ground-water 

age) direction along both flow paths (fig. 17).

The generally upward trend in 87Sr/86Sr ratios along 

ground-water flow paths is the result of subtle mineralogical 

controls such as the integration of more 87Sr from the dissolution of strontium-bearing minerals such as K-feldspar, biotite, 

and muscovite. Also, the longer ground water is in contact 

with the mineral matrix of the aquifer, the larger the 87Sr/86Sr 

ratio as the water approaches equilibrium with the isotope 

ratio of the aquifer mineral matrix. 

Although an east-to-west upward trend in 87Sr/86Sr ratios 

along Ozark aquifer flow paths might be expected, a sudden 

or abrupt change in the trend might be an indication of ground 

water with different geochemical characteristics mixing with 

flow-path water. Such an abrupt change in 87Sr/86Sr ratio 

between two successive wells is evident in ratios from the 

westerly flow path between wells 13 and 12 (fig. 17). The 

increase in 87Sr/86Sr ratios between wells 13 and 12 represents 60 percent of the increase for the entire flow path from 

well 25 (the flow-path point where increase starts) to well 

12. The increase in 87Sr/86Sr ratios between wells 13 and 12 

is supported by a 650-percent increase in Sr+2 concentration 

from well 13 to well 12, far greater than any other segment 

along either flow path. It is believed that the abrupt change in 

87Sr/86Sr ratios and increase in Sr+2 concentrations is the result 

of the proximity of the formation water being pushed from 

the system by westerly flowing freshwater. Well 12 is located 

within the transition zone between fresh and saline water 

identified by Macfarlane and others (1981) and Macfarlane 

and Hathaway (1987). Although water from wells along the 

northwesterly flow path do not display similar abrupt changes 

in 87Sr/86Sr ratios and Sr concentrations, end-member values 

are similar for both flow paths, which probably indicates a 

transitional shift toward salinity along both flow paths.

The east-to-west transition from fresh-to-saline water 

along both flow paths also is evident in a shift in water type 

0.709

0.710

0.711

0.712

0.713

0.714

0.715

0.716

0

200

400

600

800

1,000

1,200

1,400

1,600

-20 -10 0 10 20 30 40 50 60

87SR/86SR RATIO

STRONTIUM CONCENTRATION,

IN MICROGRAMS PER LITER 

DISTANCE FROM KANSAS-MISSOURI STATE LINE, IN MILES

Kansas Missouri State line

Westerly

flow path

Sr ratio

Northwesterly flow path

2

2

12

12

13

13

17

6 17

6

19

19

23

23

25

25

21

21

24

24

26

26

Sr

concentration

EXPLANATION

26

19 Northwesterly flow-path well

 and map index number

Westerly flow-path well and

 map index number

Location of wells shown in figure 13

Figure 17. Strontium (Sr) concentrations and 87Sr/86Sr isotope 

ratios in ground water from 11 flow-path wells completed in Ozark 

aquifer of southeastern Kansas and southwestern Missouri, 2006.
Potential Effect of Mining on Water Quality 39

and composition along the flow paths. Ground water at the 

start of both flow paths is a calcium magnesium bicarbonate 

type and transitions to a sodium calcium bicarbonate type 

along the northwesterly flow path and to a sodium calcium 

chloride bicarbonate type along the westerly flow path (fig. 13) 

although the transition is much more abrupt (between wells 13 

and 12) for the westerly flow path than for the more gradually evolving northwesterly flow path. These results mirror 

the Sr concentrations and 87Sr/86Sr ratios previously presented 

as demonstrated by flow-path evolution in concentrations of 

dissolved solids, sulfate, and chloride along the two flow paths 

(fig. 18).

A summary of selected major ions indicates substantial evolution in ion concentrations over the entire flow-path 

lengths, first well to last well (table 12). Increases in ionic 

concentrations ranged from 10 percent for bicarbonate along 

the westerly flow path to approximately 20,000 percent for 

chloride along the northwesterly flow path. Although substantial increases in major-ion concentrations occurred over the 

approximately 60-mi lengths of both flow paths, the largest 

part of the increase occurred within about the last 20 to 25 mi 

(from about 10 to 15 mi east of the Kansas-Missouri State 

line). For example, all of the effective increase in concentrations for dissolved solids, sulfate, and chloride, along the westerly flow path (shown in figure 18) occurred starting at about 

13 mi east of the State line (well 23). Similarly, the increase in 

concentrations for dissolved solids, sulfate, and chloride, from 

well 17 (about 10 mi east of the State line) to well 2 along 

the northwesterly flow path represent 65, 94, and 57 percent, 

respectively, of the total increase for the entire length of the 

flow path. The general water-quality analysis is that the water 

quality in the Kansas part of the Ozark aquifer is degraded 

compared to the Missouri part.

Vertical Variability

Geophysical and well-bore flow information and depthdependent water samples were collected at Pittsburg, Kansas, 

city well 10 (PCW-10) during June through August 2007 using 

methods and procedures previously described in the “Methods 

of Investigations” section of this report. Total depth of this 

Ozark aquifer well was 1,050 ft bls with the pump at 350 ft bls 

and casing to 550 ft bls. This information is used to evaluate 

vertical ground-water flow accretion and variability in waterquality characteristics. Flow accretion and water-quality sampling were conducted under pumping conditions of 1,900 to 

2,300 gal/min. Prior to the collection of water-quality samples, 

this well had been pumped continuously for about 7 days at 

0

100

200

300

400

500

600

700

800

Northwesterly 

Westerly flow path

flow path

A. Dissolved solids

Kansas Missouri

0

20

40

60

80

100

120

140

160

180

200

0

10

20

30

40

50

60

70

80

90

100

CONCENTRATION, IN MILLIGRAMS PER LITER

C. Chloride

Northwesterly 

flow path

Westerly 

flow path

B. Sulfate

20 10 0 10 20 30 40 50 60

Northwesterly 

flow path

Westerly 

flow path

DISTANCE FROM KANSAS-MISSOURI STATE LINE, IN MILES State line

Kansas Missouri State line

Kansas Missouri State line

12

13

23

26

25

12

13

23 25 26

12

13

23

25 26

2

6

19

21 24

17

2

6

19 21 24

17

6

2

19

21

17 24

EXPLANATION

26

24 Northwesterly flow-path well

 and map index number

Westerly flow-path well and

 map index number

Location of wells shown in figure 13

Figure 18. Dissolved-solids, sulfate, and chloride concentrations 

in ground water from 11 flow-path wells completed in Ozark 

aquifer of southeastern Kansas and southwestern Missouri, 2006.
40 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

Table 12. Concentrations of dissolved solids and selected major ions and overall percentage change along westerly and 

northwesterly ground-water flow paths in Ozark aquifer of southeastern Kansas and southwestern Missouri, 2006.

[mg/L, milligrams per liter]

Constituent Starting concentration, first well 

(mg/L)

Ending concentration, last well 

(mg/L)

Overall change 

(percent)

Westerly flow path

Dissolved solids 190 560 190

Calcium 39 46 18

Magnesium 19 21 11

Sodium 4.1 120 2,800

Bicarbonate 200 220 10

Sulfate 13 40 210

Chloride 1.8 190 10,000

Northwesterly flow path

Dissolved solids 130 680 420

Calcium 27 76 180

Magnesium 14 33 140

Sodium 1.4 110 7,800

Bicarbonate 140 320 130

Sulfate 13 94 620

Chloride .8 160 20,000
Potential Effect of Mining on Water Quality 41

the lesser flow rate. Analytical results of water-quality samples 

are presented in table 18 in the “Supplemental Information” 

section at the back of this report.

Nearly all ground-water flow into the borehole of city 

well PCW-10 occurred below the 750-ft bls level in the well 

with the majority of flow (77 percent) entering from two 

relatively thin layers (837–857 and 977–997 ft bls; fig. 19C). 

These water-contributing zones generally corresponded to 

smaller but undulating resistivity (relative to upper formations, 

fig. 19B) and fairly consistent natural gamma counts (fig. 

19A), which generally indicate undifferentiated formations. 

The exception to the gamma data was a thin layer around 860 

ft bls that may represent a shale formation (fig. 19A). 

Water quality in city well PCW-10 was determined within 

the flow-accretion zone previously discussed (fig. 19C). For 

the most part, water quality changed only minimally from the 

deepest sample to the well-head sample with the exception 

of chloride that doubled in concentration from about 50 to 

100 mg/L between 1,050 bls and second and third samples 

(just below and just above 900 ft bls) (fig. 19E). Subsequent 

inflow to the well above 800 ft bls reduced chloride concentration to about 80 mg/L and, thereafter, remained fairly consistent up to and including the 350 ft bls well-head sample. There 

does not seem to be much evidence of substantially qualitydegraded water upwelling from geologic formations below the 

well. The chloride concentrations in the two relataively thin 

200 700 1,200 Dissolved solids Specific conductance

Well-head 

concentration

50 80 110 Sulfate Chloride

0 50 100

Depth of

pump

Bottom of

steel casing

Water

level

CONSTITUENT CONCENTRATION,

IN MILLIGRAMS PER LITER

DISSOLVED SOLIDS, IN MILLIGRAMS

PER LITER, OR SPECIFIC CONDUCTANCE,

IN MICROSIEMENS PER CENTIMETER

CUMULATIVE FLOW AT WELL

HEAD (2,300 GALLONS PER

MINUTE), IN PERCENT

Land surface DEPTH, IN FEET BELOW LAND SURFACE

NATURAL GAMMA COUNTS

PER SECOND

0 40 80 120 160

200

100

300

400

500

600

700

800

900

1,000

1,100

2 10 100 2,000

NORMAL 16-INCH RESISTIVITY,

IN OHM - METERS

A. B. C. D. E.

JUNE 8, 2007 AUGUST 6-7, 2007 AUGUST 13-14, 2007

Figure 19. Selected results of geophysical logging, well-bore flow accretion, and depth-dependent water-quality sampling at Pittsburg, 

Kansas, city well 10, June–August 2007, showing vertical variability in ground-water flow and water quality.
42 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

layers near 900 ft bls were higher compared to the shallower 

samples above 800 ft bls, which may indicate that water below 

800 ft bls is more saline.

Summary

The Ozark aquifer is part of the regionally important 

Ozark Plateaus aquifer system that occurs in parts of Arkansas, Kansas, Missouri, and Oklahoma. The Ozark aquifer is a 

source of freshwater for municipal, domestic, industrial, and 

irrigation uses, and as such, an interstate concern exists for 

the long-term sustainability of the resource and protection 

of the aquifer from water-quality degradation. Water quality 

in supply wells completed in the Ozark aquifer potentially 

could be degraded with increased water demand from a 

growing population. Increases in pumping capacity at major 

population centers along the Kansas-Missouri State line or in 

northeastern Oklahoma may lower water levels in the Ozark 

aquifer such that, locally, the natural east-to-west flow gradient 

reverses and saline water from the western part of the aquifer 

migrates toward the pumping centers. Additionally, upwelling 

of saline water from lower geologic strata may be possible at 

the pumping centers. Lower water levels in the Ozark aquifer 

will increase the hydraulic gradient between an overlying 

aquifer system (Springfield Plateau aquifer) and the Ozark 

aquifer. This increased gradient may draw highly mineralized or contaminated water in the Springfield Plateau aquifer 

through areas where the intervening confining unit is thinner 

or more permeable or through older or abandoned wells or 

mining-related exploratory drill holes that are open to both the 

Springfield Plateau and Ozark aquifers. 

Because of quantity and quality concerns with the Ozark 

aquifer, the State of Kansas in 2004 issued a moratorium on 

new appropriations from the Ozark aquifer in Kansas with 

the exclusion of domestic supplies, requests for less than 

5 acre-ft of water per year, or temporary and term permits. 

In 2005, the U.S. Geological Survey entered into a cooperative agreement with the Kansas Water Office to develop a 

regional ground-water flow model of the Ozark and Springfield Plateau aquifers in northwestern Arkansas, southeastern 

Kansas, southwestern Missouri, and northeastern Oklahoma 

(the study area) and to conduct an assessment of current waterquality conditions within the Ozark aquifer. In 2006 and 2007, 

water-quality samples were collected from 40 water-supply 

wells completed in the Ozark aquifer and spatially distributed 

throughout the study area. The purpose of this report is to 

present the results of the water-quality assessment as part of 

this combined effort.

Water samples from the 40 water-supply wells were analyzed for physical properties, dissolved solids and major ions, 

nutrients, trace elements, and selected isotopes of selected 

elements. Many of the constituents in these water-quality 

samples are regulated in drinking-water supplies by the U.S. 

Environmental Protection Agency (USEPA) and, as such, were 

evaluated on the basis of these regulatory criteria.

Physical properties measured at the time of sample collection included specific conductance, pH, water temperature, 

turbidity, dissolved oxygen, and reduction-oxidation (redox) 

potential. Specific conductance of water from the sampled 

wells was less than 500 μS/cm (microsiemens per centimeter 

at 25°C) for about one-half (21 of 40) of the wells, as indicated by the median value of 470 μS/cm. The other 19 wells 

had specific conductance values in the range of about 500 to 

1,890 μS/cm. Generally, water from wells located in Missouri 

had the smallest specific conductance values, and overall, 

Kansas had the largest. The pH of water from sampled wells 

in the study area had a median value of 7.56 standard units. 

USEPA has established a Secondary Drinking-Water Standard (SDWR) range of 6.5 to 8.5 standard units, and water 

from all sampled wells was within this guideline. Dissolvedoxygen concentrations in water from most wells were small 

as indicated by a median dissolved-oxygen concentration of 

0.16 mg/L (milligrams per liter). Six wells had no measurable dissolved oxygen (less than 0.01 mg/L), 24 wells had 

dissolved-oxygen concentrations between 0.01 and 0.28 mg/L, 

and the remaining seven wells had dissolved-oxygen concentrations between 1.4 and 2.0 mg/L. The turbidity of water from 

the wells generally was small as indicated by a median value 

of 0.20 NTU (nephelometric turbidity units). However, water 

from three wells exceeded the USEPA Maximum Contaminant Level (MCL) of 5 NTU with turbidity values of 5.8 to 

25 NTU. Redox (oxidation-reduction) potential was measured 

for water from 32 of the 40 wells sampled for this study. 

Redox potential relative to a standard hydrogen electrode 

ranged from -110 to 380 mV (millivolts), with a median value 

of 40 mV.

Concentrations of dissolved solids from the 40 sampled 

water-supply wells ranged from 130 to 1,100 mg/L, with a 

median value of 270 mg/L. Water from about one-fourth of 

the wells exceeded the USEPA 500-mg/L SDWR for dissolved 

solids. The majority of these wells were located in Kansas. 

The largest dissolved-solids concentrations determined during 

this investigation probably are related to a general transition from freshwater to saline water in the Ozark aquifer in 

an east-to-west trend across the study area. Water from most 

sampled wells in Missouri is a calcium bicarbonate or calcium 

magnesium bicarbonate type, whereas water from wells in 

Kansas transitions to a sodium bicarbonate, sodium bicarbonate chloride, or sodium chloride type. 

Chloride concentrations ranged among the sampled 

wells from 0.8 to 490 mg/L, with a median concentration 

of 38 mg/L. Water from two wells exceeded the 250-mg/L 

SDWR for chloride. The smallest chloride concentrations 

were found in water from wells in the eastern part of the study 

area, and concentrations progressively increased in a westerly 

direction. 

Sodium concentrations ranged from 1.4 to 403 mg/L, 

with a median concentration of 38 mg/L. USEPA has not 

established an SDWR or MCL for sodium in drinking water 
Summary 43

but has listed a health-based advisory level (HAL) of 20 mg/L 

for individuals on a 500 mg/d restricted sodium diet. Water 

samples from 23 wells had concentrations that exceeded this 

advisory level. All but 2 of the 15 wells sampled in Kansas 

yielded samples with sodium concentrations greater than 

20 mg/L, whereas only three wells located in the upgradient 

part of the study area (Missouri) had sodium concentrations 

greater than 20 mg/L. 

Sulfate concentrations ranged from 0.4 to 470 mg/L, with 

a median concentration of 16 mg/L. Water from two wells 

had sulfate concentrations larger than the 250-mg/L USEPA 

SDWR. Sulfate concentrations generally were largest in samples from wells located in the western part of the study area. 

Fluoride concentrations in ground-water samples collected during this investigation generally were less than 

1.0 mg/L, with a median concentration of 0.48 mg/L. However, samples from seven wells had fluoride concentrations 

of 1.0 mg/L or larger, and concentrations ranged from 1.0 to 

4.4 mg/L. Fluoride concentrations in samples from four wells 

exceeded the 2.0-mg/L USEPA SDWR, whereas the concentration in water from one well exceeded the 4.0-mg/L MCL. 

Concentrations of magnesium, potassium, bromide, 

and silica generally were small in water from sampled wells 

relative to other major ions. The USEPA has not established 

drinking-water standards for these four ions.

Generally, nutrient concentrations in water from the 

40 wells were small. Nitrite and nitrite plus nitrate concentrations generally were less than method reporting limits but 

were detected in water from nine wells. Nitrite plus nitrate 

concentrations in water from the 40 sampled wells ranged 

from an estimated 0.03 to 2.0 mg/L, with a median concentration of less than 0.06 mg/L. Additionally, all determined 

nitrate concentrations were equal to or substantially less than 

the 2.0-mg/L national average background concentration for 

ground water. 

Total phosphorus and orthophosphate as phosphorus 

typically were present only in small concentrations in water 

from the 40 sampled wells. Total phosphorus was detected 

only in water from eight wells. Total phosphorus concentrations in water from the 40 wells ranged from an estimated 

0.002 to 0.033 mg/L, with a median concentration of less than 

0.006 mg/L. Concentrations of orthophosphate as phosphorus 

ranged from an estimated 0.003 to 0.015 mg/L, with a median 

concentration of an estimated 0.004 mg/L. Most of the phosphorus in water from the 40 sampled wells was in the form 

of orthophosphate as phosphorus. Water from 90 percent of 

sampled wells had small reportable concentrations of ammonia with a range from an estimated 0.01 to 0.43 mg/L and a 

median concentration of 0.07 mg/L. Ammonia is the dominant 

nitrogen-containing nutrient in sampled wells in the Ozark 

aquifer and represents most of the total nitrogen.

Most trace elements in ground water analyzed during this 

investigation were present in concentrations less than waterquality standards. In fact, many trace constituents frequently 

were not detected or detected in small concentrations. Seventeen elements (antimony, arsenic, beryllium, cadmium, 

chromium, cobalt, copper, lead, mercury, molybdenum, 

nickel, selenium, silver, thallium, uranium, vanadium, and 

zinc) had median concentrations less than 1.0 μg/L (micrograms per liter) and were not detected in about 70 percent 

of the samples. Silver was not detected in any of the wells. 

Seven constituents had median concentrations greater than 1.0 

μg/L—aluminum, barium, boron, iron, lithium, manganese, 

and strontium. Additionally, nine trace elements had a maximum concentration greater than 5.0 μg/L—aluminum, barium, 

boron, iron, lithium, manganese, molybdenum, strontium, and 

zinc. Iron, lead, and manganese were the only trace elements 

found in concentrations that exceeded USEPA drinking-water 

criteria. Iron concentrations ranged from an estimated 3.0 to 

3,200 μg/L, with a median value of 32 μg/L. Water from four 

wells exceeded the 300-μg/L USEPA SDWR for iron. Lead 

was not detected in water from most wells. Where it was 

detected, lead was present at concentrations less than 1.0 μg/L, 

substantially less than the USEPA Action Level of 15 μg/L; 

however, 12 wells had measurable lead concentrations that 

exceeded the USEPA MCLG of 0 μg/L. Manganese concentrations ranged from 0.32 to 95 μg/L, with a median value 

of 1.8 μg/L, and water from two wells exceeded the USEPA 

SDWR of 50 μg/L. 

Analyses of relations between the stable-isotopes δ18O 

and δ2H in water from 11 wells along two selected groundwater flow paths indicate that Ozark aquifer water is of a 

“recent” meteoric source because of similarity to the established Global Meteoric Water Line and a global precipitation 

relation. Results of tritium analyses indicate that ground water 

probably was recharged more than 60 years ago; however, 14C 

results are ambiguous at best and an upper age limit could not 

be determined. Results of 87Sr/86Sr-isotope ratios indicate that, 

along at least one of the flow paths, mixing of saline water 

from the western part of the study area may be occurring in a 

transitional area near the Kansas-Missouri State line. Analyses 

of major-ion results also indicate a transition from freshwater 

to saline water along both flow paths. Generally, ground water 

along flow paths evolves from a calcium magnesium bicarbonate type to a sodium calcium bicarbonate or a sodium calcium 

chloride bicarbonate type. However, much of this evolution 

occurs within the last 20 to 25 mi of the 60-mi flow paths as it 

approaches the transition zone near the Kansas-Missouri State 

line. The general water-quality analysis is that the water in the 

Kansas part of the Ozark aquifer is degraded compared to the 

Missouri part.

Additionally, analysis of 3H and 14C indicated that there 

was possible leakage of younger ground water into the lower 

Ozark aquifer. This may be caused by cracks or fissures in the 

intervening confining unity, poorly constructed or abandoned 

wells, or a result of historic mining activities.

Geophysical and well-bore flow information and depthdependent water samples were collected at Pittsburg, Kansas, 

city well 10 (PCW-10) during June through August 2007 to 

evaluate vertical ground-water flow accretion and variability 

in water-quality characteristics. Flow accretion and waterquality sampling were conducted under pumping conditions 
44 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

of 1,900 to 2,300 gal/min. Nearly all ground-water flow into 

the borehole of city well PCW-10 occurred below the 750-ft 

depth with the majority of flow (77 percent) entering from two 

relatively thin layers (837–857 and 977–997 ft bls). For the 

most part, water quality changed little from the deepest sample 

to the well-head sample. There is not much evidence of 

substantially quality-degraded water upwelling from geologic 

formations below the well. However, more saline water may 

exist below the bottom of the well.

Acknowledgments

An interstate reconnaissance of ground-water quality requires the participation of many people to collect the 

samples and conduct the tests necessary for a viable assessment. Appreciation is expressed to well owners in the study 

area for granting access to their wells for collection of waterquality samples. Particular appreciation is extended to Stephen 

Gillis and William Beasley of the city of Pittsburg, Kansas, for 

allowing geophysical logging and vertical-flow measurements 

in a city municipal-supply well and for providing supporting 

equipment for these activities. Many USGS personnel were 

involved in well selection, permission acquisition, and sample 

collection. These included John Czarnecki and Jonathan Gillip 

(Arkansas); Pat Finnegan and Mark Lysaught (Kansas); John 

Schumacher, Doug Mugel, and Paul Brenden (Missouri); and 

Mark Becker, Carol Becker, and Marvin Abbott (Oklahoma). 

Appreciation also is extended to Allen Macfarlane (Kansas 

Geological Survey) for providing support and permission 

acquisition for wells sampled in Kansas, Greg Stanton (USGS, 

Texas) for conducting geophysical logging, Jerrod Smith and 

James Greer (USGS, Oklahoma) for measurement of borehole 

flow and collection of depth-dependent samples in a Pittsburg, 

Kansas, municipal-supply well, and for members of the Technical Advisory Committee for this study who provided review 

comments for this report.

References Cited

Abernathy, G.E., 1941, Ground-water resources of Mississippian and older rocks in Bourbon, Crawford, Cherokee, and 

Labette Counties, southeastern Kansas: Kansas Geological 

Survey Bulletin 38, part 8, p. 221–236.

Adamski, J.C., 1997, Nutrients and pesticides in ground water 

of the Ozark Plateaus in Arkansas, Kansas, Missouri, and 

Oklahoma: U.S. Geological Survey Water-Resources Investigations 96–4313, 28 p.

Adamski, J.C., Petersen, J.C., Freiwald, D.A., and Davis, J.V., 

1995, Environmental and hydrologic setting of the Ozark 

Plateaus study unit, Arkansas, Kansas, Missouri, and Oklahoma: U.S. Geological Survey Water-Resources Investigations Report 94–4022, 69 p.

Allard, Bert, 1995, Groundwater, in Salbu, Brit, and Steinnes, 

Eilive, eds., Trace elements in natural waters: Boca Raton, 

Florida, CRC Press, p. 151–176.

American Public Health Association, American Water Works 

Association, and Water Environment Federation, 1998, 

Standard methods for the examination of water and wastewater (20th ed.): Washington, D.C., American Public Health 

Association, part 2000, p. 54

Anderson, C.W., 2005, Turbidity (version 2.1): U.S. Geological Survey Techniques of Water-Resources Investigations, 

book 9, chap. A6, section 6.7, information available on 

Web, accessed March 6, 2008, at http://pubs.water.usgs.gov/

twri9A6/

Angelo, R.T., Cringan, M.S., Chamberlain, D.L., Stahl, A.J., 

Haslouer, S.G., and Goodrich, C.A., 2007, Residual effects 

of lead and zinc mining on freshwater mussels in the Spring 

River Basin (Kansas, Missouri, and Oklahoma, USA): The 

Science of the Total Environment, v. 384, p. 467–496.

Bailey, E.H.S., 1911, Preliminary report on stream pollution 

by mine water supplies of Kansas: U.S. Geological Survey 

Water-Supply Paper 273, p. 349–361.

Barks, J.H., 1977, Effects of abandoned lead and zinc mines 

and tailings piles on water quality in the Joplin area, Missouri: U.S. Geological Survey Water-Resources Investigations Report 77–75, 49 p.

Barks, J.H., 1978, Water quality in the Ozark National Scenic 

Riverways, Missouri: U.S. Geological Survey Water-Supply 

Paper 2048, 57 p.

Beukens, R.P., 1992, Radiocarbon accelerator mass spectrometry—background, precision, and accuracy, in Taylor, 

R.E., Long, A., and Kra, R.S., eds., Radiocarbon after four 

decades: New York, Springer-Verlag, p. 230–239.

Bouwer, Herman, 1978, Groundwater hydrology: New York, 

McGraw-Hill, 480 p.

Bretz, J.H., 1965, Geomorphic history of the Ozarks of 

Missouri: Rolla, Missouri Division of Geology and Land 

Survey, 2nd ser. v. 41, 147 p.

Brickler, O.P., and Jones, B.F., 1995, Main facts affecting the 

compositions of natural waters, in Salbu, Brit, and Steinnes, 

Eiliv, eds., Trace elements in natural waters: Boca Raton, 

Florida, CRC Press, Inc., p. 1–20.

Canter, L.W., 1996, Nitrates in groundwater: New York, Lewis 

Publishers, 263 p.

Christenson, S.C., Parkhurst, D.L., and Fairchild, R.W., 1990, 

Geohydrology and water quality of the Roubidoux aquifer, 

northeastern Oklahoma: U.S. Geological Survey Open-File 

Report 90–570, 110 p.
References Cited 45

Clark. I.D., and Fritz, Peter, 1997, Environmental isotopes in 

hydrology: New York, Lewis Publishers, 328 p.

Coplen, T.B., Wildman, J.D., and Chen, J., 1991, Improvements in the gaseous hydrogen-water equilibration technique for hydrogen isotope ratio analysis: Analytical 

Chemistry, v. 63, p. 910–912.

Craig, Harmon, 1961, Isotopic variations in meteoric waters: 

Science, v. 133, p. 1,702–1,703.

Darr, J.M., 1978, Geochemistry of ground water, southwestern Missouri: Columbia, University of Missouri, Master’s 

thesis, 113 p.

DeHay, K.L., 2003, Assessment and comparison of 1976–77 

and 2002 water quality in mineshafts in the Picher Mining 

District, northeastern Oklahoma and southeastern Kansas: 

U.S. Geological Survey Water-Resources Investigations 

Report 03–4248, 65 p.

Denison, R.E., 1981, Basement rocks in northeastern Oklahoma: Oklahoma Geological Survey Circular 84, 83 p.

Emmett, L.F., Skelton, John, Luckey, R.R., Miller, D.E., 

Thompson, T.L., and Whitfield, J.W., 1979, Water-resources 

and geology of the Springfield area, Missouri: Rolla, 

Missouri Division of Geology and Land Survey WaterResources Report 34, 150 p.

Epstein, S., and Mayeda, T., 1953, Variation of O-18 content 

of water from natural sources: Geochimica Cosmochimica 

Acta, v. 4, p. 213–224.

Faires, L.M., 1993, Methods of analysis by the U.S. Geological Survey National Water-Quality Laboratory—determination of metals in water by inductively coupled plasmamass spectrometry: U.S. Geological Survey Open-File 

Report 92–634, 28 p.

Faure, G., and Powell, J.L., 1972, Strontium isotope geology: 

New York, Springer-Verlag, 188 p.

Feder, G.L., 1979, Geological survey of waters in Missouri: 

U.S. Geological Survey Professional Paper 954–E, 78 p.

Feder, G.L., Skelton, John, Jeffery, H.G., and Harvey, E.J., 

1969, Water resources of the Joplin area, Missouri: Rolla, 

Missouri Division of Geology and Land Survey WaterResources Report 24, 97 p.

Fenneman, N.M., 1938, Physiography of eastern United 

States: New York, McGraw-Hill Book Co., Inc., 714 p.

Fishman, M.J., 1993, Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory—determination of inorganic and organic constituents in water 

and fluvial sediments: U.S. Geological Survey Open-File 

Report 93–126, 217 p.

Gibson, A.M., 1972, Wilderness bonanza—the Tri-State District of Missouri, Kansas, and Oklahoma: Norman, Oklahoma, University of Oklahoma Press, 362 p.

Gillip, J.A., Czarnecki, J.B., and Mugel, D.N., 2008, Potentiometric surfaces in the Springfield Plateau and Ozark 

aquifers of northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 

2006: U.S. Geological Survey Scientific Investigations 

Report 2007–5253, 25 p.

Gleason, J.D., Friedman, I., and Hanshaw, B.B., 1969, Extraction of dissolved carbonate species from natural water for 

carbon-isotope analysis: U.S. Geological Survey Professional Paper 650–D, p. D248–D250.

Harvey, F.E., 2001, Use of NADP archive samples to determine the isotope composition of precipitation—characterizing the meteoric input function for use in ground water 

studies: Ground Water, v. 39, no. 3, p. 380–390.

Haworth, Erasmus, Crane, W.R., and Rogers, A.F., 1904, 

Special report on lead and zinc: Lawrence, The University 

Geological Survey of Kansas, v. 8, 509 p.

Hem, J.D. 1992, Study and interpretation of the chemical 

characteristics of natural water (3rd ed.): U.S. Geological 

Survey Water-Supply Paper 2254, 263 p.

Hill, M.C., Banta, E.R., Harbaugh, A.W., and Anderman, 

E.R., 2000, MODFLOW-2000, The U.S. Geological Survey 

modular ground-water model user guide to the observation, 

sensitivity, and parameter-estimation processes and three 

post-processing programs: U.S. Geological Survey OpenFile Report 00–184, 209 p.

Imes, J.L., 1990, Major geohydrologic units in and adjacent to 

the Ozark Plateaus Province, Missouri, Arkansas, Kansas, 

and Oklahoma—Ozark aquifer: U.S. Geological Survey 

Hydrologic Atlas HA–711–E, 3 sheets, scale 1:750,000.

Imes, J.L., and Davis, J.V., 1991, Water type and concentration 

of dissolved solids, chloride, and sulfate in ground water 

from the Ozark aquifer: U.S. Geological Survey Hydrologic 

Investigations Atlas HA–711–K, 4 sheets, scale 1:750,000.

Imes, J.L., and Emmett, L.F., 1994, Geohydrology of the 

Ozark Plateaus aquifer system in parts of Missouri, Arkansas, Oklahoma, and Kansas: U.S. Geological Survey Professional Paper 1414–D, 127 p.

Izbicki, J.A., Christensen, A.H., and Hanson, R.T., 1999, U.S. 

Geological Survey combined well-bore flow and depthdependent water sampler: U.S. Geological Survey Fact 

Sheet FS–196–99, 2 p.

Jorgensen, D.G., 1989, Paleohydrology of the central United 

States: U.S. Geological Survey Bulletin 1989–D, 32 p.
46 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

Jorgensen, D.G., Helgesen, J.O., and Imes, J.L., 1993, 

Regional aquifers in Kansas, Nebraska, and parts of Arkansas, Colorado, Missouri, New Mexico, Oklahoma, South 

Dakota, Texas, and Wyoming—geohydrologic framework: 

U.S. Geological Survey Professional Paper 1414–B, 83 p.

Jorgensen, D.G., Helgesen, J.O., Signor, D.C., Leonard, R.B., 

Imes, J.L., and Christenson, S.C., 1996, Analysis of regional 

aquifers in the central Midwest of the United States in 

Kansas, Nebraska, and parts of Arkansas, Colorado, Missouri, New Mexico, Oklahoma, South Dakota, Texas, and 

Wyoming—summary: U.S. Geological Survey Professional 

Paper 1414–A, 67 p.

Juracek, K.E., 2006, Sedimentation and occurrence and trends 

of selected chemical constituents in bottom sediment, 

Empire Lake, Cherokee County, Kansas, 1905–2005: U.S. 

Geological Survey Scientific Investigations Report 2006–

5307, 79 p.

Kendall, Carol, and Caldwell, E.A., 1998, Fundamentals of 

isotope geochemistry, in Kendall, Carol, and McDonnell, 

J.J., eds, Isotope tracers in catchment hydrology: Amsterdam, Elsevier Science, p. 51–86.

Kendall, Carol, and Coplen, T.B., 2001, Distribution of 

oxygen-18 and deuterium in river waters across the United 

States: Hydrological Processes, v. 15, p. 1,363–1,393.

Kendall, Carol, Sklash, M.G., and Bullen, T.D., 1995, Isotope 

tracers of water and solute sources in catchments, in Trudgill, S.T., ed., Solute modeling in catchment systems: New 

York, John Wiley & Sons, p. 261–303.

Keroher, R.P., and Kirby, J., 1948, Upper Cambrian and Lower 

Ordovician rocks in Kansas: Kansas Geological Survey 

Bulletin 72, 140 p.

Kleeschulte, M.J., Mesko, T.O., and Vandike, J.E., 1985, 

Appraisal of the ground-water resources of Barton, Vernon, 

and Bates Counties, Missouri: Rolla, Missouri Division 

of Geology and Land Survey Water-Resources Report 36, 

74 p.

Koenig, J.W., 1961, The stratigraphic succession in Missouri: 

Missouri Division of Geology and Land Survey, v. 40, 2nd 

ser., 185 p.

Ma, Y., and Liu, C., 1999, Using strontium isotopes to trace 

nutrient element circulation and hydrochemical evolution 

within an ecosystem: Advance Earth Sciences, v. 4, no. 4, 

p. 377–382.

Macfarlane, P.A., and Hathaway, L.R., 1987, The hydrogeology and chemical quality of ground waters from the lower 

Paleozoic aquifers in the Tri-State region of Kansas, Missouri, and Oklahoma: Kansas Geological Survey Ground 

Water Series 9, 37 p.

Macfarlane, P.A., Whittemore, D.O., and Hathaway, L.R., 

1981, A report to the Kansas Department of Health and 

Environment on the hydrology and chemical quality in the 

Lower Paleozoic aquifers in southeast Kansas and adjoining 

areas of Missouri and Oklahoma: Kansas Geological Survey 

Open-File Report 81–16, 48 p.

Maloszewski, P., and Zuber, A., 1991, Influence of matrix 

diffusion and exchange reactions on radiocarbon ages in fissured carbonate aquifers: Water Resources Research, v. 27, 

p. 1,937–1,945.

McCracken, M.H., 1964, The Cambo-Ordovician rocks of 

northeastern Oklahoma and adjacent areas: Tulsa Geological Society Digest, v. 32, p. 49–75.

McCracken, M.H., 1967, Structure, in Mineral and water 

resources of Missouri: Rolla, Missouri Division of Geology 

and Land Survey, v. 43, p. 20–21.

McCracken, M.H., 1971, Structural features of Missouri: 

Rolla, Missouri Division of Geology and Land Survey 

Report of Investigations 49, 99 p.

Mueller, D.K., and Helsel, D.R., 1996, Nutrients in the 

Nation’s waters—too much of a good thing?: U.S. Geological Survey Circular 1136, 24 p.

Nace, R.L., 1960, Water management, agriculture, and groundwater supplies: U.S. Geological Survey Circular 415, 12 p.

National Climatic Data Center, 2008, Climate normals: U.S. 

Department of Commerce, information available on Web, 

accessed April 5, 2008, at http://www5.ncdc.noaa.gov/

cgi-bin/climatenormals/climatenormals.pl

Parkhurst, D.C., 1987, Chemical analyses of water samples 

from the Picher mining area, northeast Oklahoma and 

southeast Kansas: U.S. Geological Survey Open-File Report 

87–453, 43 p.

Parkhurst, D.L., 1988, Mine-water discharge, metal loading, 

and chemical reactions, in Ragone, S.E., ed., U.S. Geological Survey program on toxic waste ground-water contamination, Proceedings of the second technical meeting, Cape 

Cod, Massachusetts, October 21–25, 1985: U.S. Geological 

Survey Open-File Report 86–0481, p. D11–D15.

Patton, C.J., and Kryskalla, J.R., 2003, Methods of analysis 

by the U.S. Geological Survey National Water Quality 

Laboratory—evaluation of alkaline persulfate digestion as 

an alternative to Kjeldahl digestion for determination of 

total and dissolved nitrogen and phosphorus in water: U.S. 

Geological Survey Water-Resources Investigations Report 

03–4174, 33 p.

Playton, S.J., Davis, R.E., and McClaflin, R.G., 1980, Chemical quality of water in abandoned zinc mines in northeastern Oklahoma and southeastern Kansas: U.S. Geological 

Survey Open-File Report 78–294, 67 p.
References Cited 47

Pope, L.M., 2005, Assessment of contaminated streambed 

sediment in the Kansas part of the historic Tri-State Lead 

and Zinc Mining District, Cherokee County, 2004: U.S. 

Geological Survey Scientific Investigations Report 2005–

5251, 61 p.

Reed, E.W., Schoff, S.L., and Branson, C.C., 1955, Groundwater resources of Ottawa County, Oklahoma: Oklahoma 

Geological Survey Bulletin 72, 203 p.

Révész, Kinga, and Qi, Haiping, 2006, Determination of the 

δ(34S/32S) of sulfate in water—RSIL Lab Code 1951, chap. 

C10, in Révész, Kinga, and Coplen, T.B., eds., Methods 

of the Reston Stable Isotope Laboratory: Reston, Virginia, 

U.S. Geological Survey, Techniques and Methods, book 10, 

sec. C, chap. 10, 33 p.

Rozanski, K., Araguas-Araguas, L., and Gonfiantini, R., 1993, 

Isotopic patterns in modern global precipitation, in Continental isotope indicators of climate: American Geophysical 

Union Monograph, no. 78, p. 1–36.

Seal, R.R., II, 2008, Stable isotopes and mineral resource 

investigations in the United States: Reston, Virginia, 

information available on Web, accessed June 2008, at 

http://pubs.usgs.gov/info/seal2/

Snider, L.C., 1915, Geology of a portion of northeastern Oklahoma: Oklahoma Geological Survey Bulletin 24, part 1, 

130 p.

Spruill, T.B., 1987, Assessment of water resources in leadzinc mined areas in Cherokee County, Kansas, and adjacent 

areas: U.S. Geological Survey Water-Supply Paper 2268, 

68 p.

Stramel, G.J., 1957, The hydraulic properties of the Ordovician rocks at Pittsburg, Kansas: Geological Survey of 

Kansas Bulletin 127, part 5, 178 p.

Stuiver, M., and Polach, H.A., 1977, Discussion—reporting of 14C data: Radiocarbon, v. 19, no. 3, p. 355–363.

Thatcher, L.L., and Janzer, V.J., 1977, Methods for determination of radioactive substances in water and fluvial 

sediments: U.S. Geological Survey Techniques of WaterResources Investigations, book 5, chap. A5, 95 p.

Thompson, T.L., 1991, Paleozoic succession in Missouri—

part 2, Ordovician System: Rolla, Missouri Division of 

Geology and Land Survey Report of Investigations 70, 

282 p.

U.S. Environmental Protection Agency, 1986, Quality criteria 

for water, 1986: U.S. Environmental Protection Agency 

Report 440/5–86–001, unnumbered pages.

U.S. Environmental Protection Agency, 2006, 2006 Edition of 

the drinking water standards and health advisories: Washington, D.C., EPA 822–R–06–013, summer 2006, information available on Web, accessed March 6, 2008, at 

http://www.epa.gov/waterscience/criteria/drinking/

dwstandards.pdf

Wilde, F.D., Radtke, D.B., Gibs, Jacob, and Iwatsubo, R.T., 

eds., 1999, Collection of water samples: U.S. Geological Survey Techniques of Water-Resources Investigations, 

book 9, chap. A4, information available on Web, accessed 

September 5, 2006, at http://pubs.water.usg.gov/twri9A4/

Williams, L.L., 1948, Contamination of deep-water wells in 

southeastern Kansas: Kansas Geological Survey Bulletin 

70, part 2, p. 13–28.

Zeller, D.E., ed., 1968, The stratigraphic succession in Kansas: 

Kansas Geological Survey Bulletin 189, 81 p. 

Supplemental Information
50 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

Table 13. Water-quality properties or constituents analyzed in ground water from 40 water-supply wells completed in Ozark aquifer, 

northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07. 

[μS/cm, microsiemens per centimeter; oC, degrees Celsius; NTU, nephelometric turbidity units; mg/L, milligrams per liter; mV, millivolts, relative to standard 

hydrogen electrode; --, not applicable; CaCO3, calcium carbonate; USGS, U.S. Geological Survey; SC, schedule code; C, carbon; δ, del; H, hydrogen; permil, 

ratio per thousand parts; pCi/L, picocuries per liter; O, oxygen; pct, percent; Sr, strontium; S, sulfur]

Constituent

(unit of measurement) Analytical method reporting limit Constituent Analytical method reporting limit

Physical properties 

Specific conductance (μS/cm) 2.6 pH (standard units) .01

Water temperature (°C) .1 Turbidity (NTU) 0.05

Dissolved oxygen (mg/L) 0.01 Oxidation-reduction (redox) 

potential (mV)

--

Alkalinity (as CaCO3) 1.0 

Dissolved solids and major ions, USGS SC2750, in milligrams per liter

Dissolved solids 10 Calcium .04

Magnesium .02 Sodium .12

Potassium .02 Bicarbonate 1.0 

Carbonate .10 Sulfate .18

Chloride .12 Fluoride .12

Bromide .02 Silica .018 

Nutrients, USGS SC2752, filtered, in milligrams per liter

Nitrite, as nitrogen .002 Nitrite plus nitrate, as nitrogen .06

Ammonia, as nitrogen .02 Total nitrogen .06

Phosphorus 0.004–0.006 Orthophosphate, as phosphorus .006

Trace elements, USGS SC2710, USGS SC2750, and mercury, USGS LC2707, filtered, in micrograms per liter

Aluminum 1.6 Antimony 0.06–0.20

Arsenic .12 Barium .40

Beryllium .06 Boron 8.0

Cadmium .04 Chromium .12

Cobalt .04 Copper 0.40–1.2

Iron 6.0 Lead 0.08–0.12

Lithium 1.0 Manganese .20

Mercury .01 Molybdenum 0.12–0.40

Nickel .06 Selenium .08

Silver 0.08–1.0 Strontium .80

Thallium .04 Uranium, natural .04

Vanadium 0.04–0.10 Zinc .60

Isotopes (units or reporting limits)

δ13C permil 14C count pct modern

δ2H permil Tritium .04 pCi/L

δ18O permil δ34S permil

87Sr/86Sr ratio
Supplemental Information 51

Table 14. Results of measurements or analysis of physical properties in ground water from 40 water-supply wells completed in 

Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07. 

[μS/cm, microsiemens per centimeter at 25 oC; oC, degrees Celsius; mg/L, milligrams per liter; NTU, nephelometric turbidity units; mV, millivolts; CaCO3, 

milligrams per liter as calcium carbonate; P, primary; CR, concurrent replicate; <, less than; --, not determined]

Map 

index 

number 

(fig. 4)

Date of sample 

collection 

(month/day/

year)

Time 

(24-

hour)

Sample 

type

Specific 

conductance 

(μS/cm)

pH, field 

(standard 

units)

Water 

temperature (o

C)

Dissolved 

oxygen 

(mg/L)

Turbidity 

(NTU)

Oxidation-reduction 

(redox) potential (mV 

relative to a standard 

hydrogen electrode)

Alkalinity 

as CaCO3 

(mg/L)

Kansas

1 09/19/2006 0910 P 1,340 7.39 19.7 <0.01 15 -100 250

2 09/19/2006 1220 P 1,170 7.17 23.9 .15 .29 -100 270

3 09/19/2006 1050 P 1,220 7.19 22.7 .05 .16 -100 280

4 09/20/2006 0830 P 678 7.40 20.3 <.01 .18 -100 240

5 09/19/2006 1420 P 909 7.20 22.5 1.6 5.8 0 280

6 09/20/2006 0950 P 888 7.28 20.4 .05 .09 -100 260

6 09/20/2006 0955 CR 888 7.28 20.4 .05 .09 -100 260

7 09/20/2006 1215 P 723 7.23 22.2 .16 .51 -110 280

8 10/11/2006 1125 P 715 7.21 23.2 .21 .17 -70 230

9 09/21/2006 1110 P 872 7.35 21.6 1.4 25 -100 290

10 09/29/2006 1140 P 483 7.45 18.2 .16 .08 120 210

11 09/21/2006 1320 P 336 7.76 18.6 .19 .14 60 120

12 09/21/2006 0925 P 1,020 7.53 20.4 .16 .12 -100 180

13 09/22/2006 0915 P 445 7.56 19.5 .28 .22 130 150

14 09/29/2006 1330 P 456 7.75 19.5 .15 .28 60 150

15 09/22/2006 1110 P 926 7.68 19.7 .18 .21 80 140

Missouri

16 05/29/2007 1550 P 437 7.59 19.7 .05 .10 50 150

17 12/13/2006 1130 P 571 7.49 21.3 .01 .44 -40 180

18 05/29/2007 1330 P 308 7.53 17.4 .26 .11 380 150

18 05/29/2007 1335 CR 308 7.53 17.4 .26 .11 -- --

19 12/13/2006 0920 P 338 7.55 19.1 <.01 .13 40 160

20 05/30/2007 1000 P 1,260 6.85 19.4 .23 .52 90 290

21 12/11/2006 1320 P 273 7.98 16.1 <.01 .73 -70 150

22 05/30/2007 0800 P 446 7.35 20.0 .11 .36 180 200

23 12/12/2006 1510 P 250 7.66 18.2 .02 .41 60 130

23 12/12/2006 1515 CR 250 7.66 18.2 .02 .41 60 130

24 12/11/2006 1610 P 236 7.76 15.3 <.01 3.7 60 110

25 12/12/2006 1120 P 253 7.72 17.7 .03 .15 180 130

26 12/12/2006 0820 P 328 7.49 15.7 <.01 .35 120 160

27 05/30/2007 1220 P 283 7.39 19.6 .07 .13 70 140

28 05/31/2007 0820 P 252 7.96 18.1 .06 .12 60 120

29 05/31/2007 1000 P 369 7.58 18.7 .10 .10 140 190

30 05/30/2007 1400 P 415 7.59 19.3 .10 .10 0 140

Oklahoma

31 05/22/2007 1130 P 1,500 6.84 19.3 -- -- -- 280

32 05/22/2007 1430 P 323 7.89 19.1 1.4 -- -- 110

33 05/21/2007 1600 P 1,890 7.70 23.2 -- -- -- 150

34 05/23/2007 1300 P 286 7.76 19.4 1.6 -- -- 110

34 05/23/2007 1305 CR 286 7.76 19.4 1.6 -- -- 110

35 05/23/2007 0930 P 809 7.99 22.9 1.8 -- -- 170

36 05/24/2007 0900 P 1,390 7.70 21.5 2.0 -- -- 150

37 05/24/2007 1500 P 377 7.15 16.9 -- -- -- 170

38 05/24/2007 1300 P 412 7.94 21.0 2.0 -- -- 130

Arkansas

39 06/01/2007 1010 P 620 8.15 18.0 .16 .75 10 270

40 06/01/2007 1140 P 963 7.76 18.2 .16 .20 -60 220
52 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

Table 15. Results of dissolved solids and major ion analyses of ground water from 40 water-supply wells completed in Ozark 

aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07.

[mg/L, milligrams per liter; primary; CR, concurrent replicate; <, less than; E, estimated; --, not determined]

Map index 

number 

(fig. 6)

Date of sample 

collection 

(month/day/year)

Time 

(24-hour)

Sample 

type

Dissolved 

solids 

(mg/L)

Calcium 

(mg/L)

Magnesium 

(mg/L)

Sodium 

(mg/L)

Potassium 

(mg/L)

Bicarbonate (mg/L)

Kansas

1 09/19/2006 0910 P 740 59 25 160 7.3 300

2 09/19/2006 1220 P 680 76 33 110 7.7 320

3 09/19/2006 1050 P 710 75 33 120 7.2 340

4 09/20/2006 0830 P 380 47 20 62 4.0 290

5 09/19/2006 1420 P 530 68 30 76 6.6 340

6 09/20/2006 0950 P 490 38 25 403 5.2 320

6 09/20/2006 0955 CR 500 56 25 81 5.1 320

7 09/20/2006 1215 P 420 61 28 52 5.6 340

8 10/11/2006 1125 P 410 54 24 58 5.0 280

9 09/21/2006 1110 P 510 53 25 99 6.6 350

10 09/29/2006 1140 P 280 51 22 17 3.6 250

11 09/21/2006 1320 P 180 31 14 16 2.2 140

12 09/21/2006 0925 P 560 46 21 120 5.8 220

13 09/22/2006 0915 P 260 49 16 21 2.0 180

14 09/29/2006 1330 P 230 36 16 23 2.3 180

15 09/22/2006 1110 P 490 41 18 110 3.8 170

Missouri

16 05/29/2007 1550 P 230 32 15 32 2.8 190

17 12/13/2006 1130 P 320 42 20 49 3.6 220

18 05/29/2007 1330 P 170 37 15 2.5 1.2 180

18 05/29/2007 1335 CR 160 37 15 2.5 1.2 --

19 12/13/2006 0920 P 190 37 17 12 2.2 190

20 05/30/2007 1000 P 1,000 250 24 18 2.5 350

21 12/11/2006 1320 P 160 34 15 1.5 .9 190

22 05/30/2007 0800 P 240 47 21 13 3.0 250

23 12/12/2006 1510 P 140 30 13 3.5 1.5 160

23 12/12/2006 1515 CR 140 31 14 3.5 1.5 160

24 12/11/2006 1610 P 130 27 14 1.4 1.3 140

25 12/12/2006 1120 P 130 30 15 1.8 1.2 160

26 12/12/2006 0820 P 190 39 19 4.1 2.2 200

27 05/30/2007 1220 P 210 32 15 4.0 1.5 170

28 05/31/2007 0820 P 140 28 13 3.0 1.3 140

29 05/31/2007 1000 P 200 43 22 2.4 1.0 230

30 05/30/2007 1400 P 240 26 11 43 1.8 170

Oklahoma

31 05/22/2007 1130 P 1,100 170 78 56 8.2 340

32 05/22/2007 1430 P 170 26 13 18 1.5 130

33 05/21/2007 1600 P 1,000 48 22 280 8.6 190

34 05/23/2007 1300 P 150 27 12 11 1.7 140

34 05/23/2007 1305 CR 150 27 12 11 1.7 140

35 05/23/2007 0930 P 420 17 7.5 140 4.5 210

36 05/24/2007 0900 P 790 45 20 200 6.4 180

37 05/24/2007 1500 P 250 69 1.6 6.1 .3 200

38 05/24/2007 1300 P 220 24 9.1 47 1.7 160

Arkansas

39 06/01/2007 1010 P 370 4.5 2.0 140 3.1 330

40 06/01/2007 1140 P 520 23 9.5 160 4.4 270
Supplemental Information 53

Table 15. Results of dissolved solids and major ion analyses of ground water from 40 water-supply wells completed in Ozark aquifer, 

northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07.—Continued

[mg/L, milligrams per liter; primary; CR, concurrent replicate; <, less than; E, estimated; --, not determined]

Map index 

number 

(fig. 6)

Date of 

sample 

collection 

(month/day/

year)

Time 

(24-hour)

Sample 

type

Carbonate 

(mg/L)

Sulfate 

(mg/L)

Chloride 

(mg/L)

Fluoride 

(mg/L)

Bromide 

(mg/L)

Silica 

(mg/L)

Kansas

1 09/19/2006 0910 P <0.1 44 250 0.97 0.64 9.8

2 09/19/2006 1220 P <.1 94 160 .83 .43 11

3 09/19/2006 1050 P <.1 94 170 .79 .48 10

4 09/20/2006 0830 P <.1 22 64 .64 .18 9.9

5 09/19/2006 1420 P <.1 78 81 .93 .23 10

6 09/20/2006 0950 P <.1 46 42 .69 .29 9.7

6 09/20/2006 0955 CR <.1 47 110 .67 .30 9.7

7 09/20/2006 1215 P <.1 58 37 .86 .12 10

8 10/11/2006 1125 P <.1 53 54 1.0 .17 10

9 09/21/2006 1110 P <.1 50 90 1.4 .27 10

10 09/29/2006 1140 P <.1 56 3.3 .74 .10 8.7

11 09/21/2006 1320 P <.1 24 18 .52 .06 9.1

12 09/21/2006 0925 P <.1 40 190 .98 .55 9.8

13 09/22/2006 0915 P <.1 45 22 .27 .09 9.0

14 09/29/2006 1330 P <.1 17 42 .36 .12 9.5

15 09/22/2006 1110 P <.1 28 180 .45 .51 8.9

Missouri

16 05/29/2007 1550 P .1 15 38 .43 .11 9.5

17 12/13/2006 1130 P <.1 18 69 .56 .22 10

18 05/29/2007 1330 P .2 11 2.4 .13 E.01 9.7

18 05/29/2007 1335 CR -- 11 2.4 .12 E.02 9.7

19 12/13/2006 0920 P <.1 17 7.4 .38 .04 9.7

20 05/30/2007 1000 P .2 470 5.5 .28 .05 11

21 12/11/2006 1320 P <.1 4.2 1.1 E.07 <.02 9.8

22 05/30/2007 0800 P .1 22 6.6 .43 .04 9.5

23 12/12/2006 1510 P <.1 13 1.0 .14 E.01 9.2

23 12/12/2006 1515 CR <.1 13 1.0 .14 <.02 9.1

24 12/11/2006 1610 P <.1 13 .8 .13 <.02 8.9

25 12/12/2006 1120 P <.1 11 1.3 E.08 <.02 9.9

26 12/12/2006 0820 P <.1 13 1.8 .34 <.20 9.4

27 05/30/2007 1220 P .2 11 2.1 .15 <.02 9.9

28 05/31/2007 0820 P .2 13 2.3 .26 E.02 9.5

29 05/31/2007 1000 P .2 11 2.1 <.10 E.02 9.3

30 05/30/2007 1400 P .7 12 42 .80 .13 9.9

Oklahoma

31 05/22/2007 1130 P .2 440 90 .13 .28 10

32 05/22/2007 1430 P .5 12 25 .25 .08 9.5

33 05/21/2007 1600 P .8 13 490 2.4 1.3 11

34 05/23/2007 1300 P .3 14 6.5 .40 .03 9.7

34 05/23/2007 1305 CR .3 14 6.5 .41 .03 9.6

35 05/23/2007 0930 P 1.2 5.8 150 3.9 .43 11

36 05/24/2007 0900 P 1.0 5.2 350 1.0 .99 10

37 05/24/2007 1500 P .2 7.3 7.4 E.08 .05 8.7

38 05/24/2007 1300 P .3 11 40 .99 .13 12

Arkansas

39 06/01/2007 1010 P .8 .4 34 4.4 .11 8.6

40 06/01/2007 1140 P .5 4.1 170 2.4 .51 10
54 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

Table 16. Results of nutrient analyses of ground water from 40 water-supply wells completed in Ozark aquifer, northwestern 

Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07.

[sample type: P, primary; CR, concurrent replicate. mg/L, milligrams per liter; N, nitrogen; P, phosphorus; <, less than; E, estimated]

Map index 

number 

(fig. 4)

Date of 

sample 

collection 

(month/day/

year)

Time 

(24-hour)

Sample 

type

Nitrite 

(mg/L as N)

Nitrite plus 

nitrate 

(mg/L as N)

Ammonia 

(mg/L as N)

Total nitrogen (nitrate 

+ nitrite + 

ammonia + 

organic-N) 

(mg/L)

Total 

phosphorus 

(mg/L)

Orthophosphate 

(mg/L as P)

1 09/19/2006 0910 P <0.002 E0.03 0.27 0.32 <0.004 E0.005

2 09/19/2006 1220 P <.002 E.03 .26 .26 <.004 E.006

3 09/19/2006 1050 P <.002 <.06 .24 .35 E.002 E.005

4 09/20/2006 0830 P <.002 <.06 .17 .14 <.004 E.005

5 09/19/2006 1420 P <.002 E.03 .20 .32 <.004 E.003

6 09/20/2006 0950 P <.002 <.06 .21 .18 <.004 E.005

6 09/20/2006 0955 CR <.002 <.06 .22 .18 <.004 E.005

7 09/20/2006 1215 P <.002 <.06 .19 .22 E.002 E.006

8 10/11/2006 1125 P <.002 <.06 .19 .42 <.006 E.005

9 09/21/2006 1110 P <.002 <.06 .29 .32 <.004 E.005

10 09/29/2006 1140 P <.002 <.06 .16 .17 <.004 <.006

11 09/21/2006 1320 P <.002 <.06 .05 .07 .027 E.004

12 09/21/2006 0925 P <.002 <.06 .25 .28 <.004 E.004

13 09/22/2006 0915 P .002 E.04 .03 E.04 <.004 E.005

14 09/29/2006 1330 P <.002 <.06 .06 .06 <.004 <.006

15 09/22/2006 1110 P <.002 <.06 .11 .09 <.004 E.005

16 05/29/2007 1550 P <.002 <.06 .08 .09 <.006 E.003

17 12/13/2006 1130 P <.002 <.06 .11 .12 <.006 E.005

18 05/29/2007 1330 P <.002 .24 <.02 .23 <.006 E.004

18 05/29/2007 1335 CR <.002 .22 <.02 .22 <.006 E.003

19 12/13/2006 0920 P <.002 <.06 .04 .07 <.006 E.004

20 05/30/2007 1000 P E.001 <.06 E.02 <.06 .009 .009

21 12/11/2006 1320 P <.002 <.06 .04 E.05 .012 .011

22 05/30/2007 0800 P <.002 <.06 .04 <.06 <.006 E.004

23 12/12/2006 1510 P <.002 <.06 E.02 E.05 <.006 E.004

23 12/12/2006 1515 CR <.002 <.06 E.02 E.03 <.006 E.004

24 12/11/2006 1610 P <.002 <.06 E.02 E.05 <.006 E.004

25 12/12/2006 1120 P <.002 E.03 E.01 E.05 .033 E.004

26 12/12/2006 0820 P <.002 <.06 .03 E.05 <.006 E.005

27 05/30/2007 1220 P <.002 <.06 <.02 <.06 <.006 E.004

28 05/31/2007 0820 P <.002 <.06 .03 <.06 <.006 E.004

29 05/31/2007 1000 P <.002 <.06 <.02 <.06 <.006 E.005

30 05/30/2007 1400 P <.002 <.06 .03 <.06 <.006 E.004

31 05/22/2007 1130 P <.002 <.06 .08 .07 <.006 <.006

32 05/22/2007 1430 P <.002 <.06 .02 E.04 <.006 E.004

33 05/21/2007 1600 P <.002 <.06 .43 .44 <.006 E.004

34 05/23/2007 1300 P <.002 <.06 E.02 <.06 <.006 E.003

34 05/23/2007 1305 CR <.002 <.06 E.02 <.06 <.006 E.003

35 05/23/2007 0930 P <.002 <.06 .24 .24 <.006 E.004

36 05/24/2007 0900 P <.002 <.30 .16 .16 <.006 E.004

37 05/24/2007 1500 P <.002 2.0 <.02 2.0 .014 .015

38 05/24/2007 1300 P <.002 <.06 .05 .08 E.006 .007

39 06/01/2007 1010 P <.002 <.06 .11 .19 <.006 E.004

40 06/01/2007 1140 P <.002 <.06 .15 .16 <.006 E.004
Supplemental Information 55

Table 17. Results of selected trace element and stable isotope analyses of ground water from 40 water-supply wells completed in 

Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07.

[μg/L, micrograms per liter; P, primary; CR, concurrent replicate; <, less than; E, estimated; d, del; permil, per thousand parts; C, carbon; H, hydrogen; O, 

oxygen; S, sulfur; Sr, strontium]

Map 

index 

number 

(fig. 4)

Date of 

sample 

collection 

(month/day/

year)

Time 

(24-hour)

Sample 

type

Aluminum 

(μg/L)

Antimony 

(μg/L)

Arsenic 

(μg/L)

Barium 

(μg/L)

Beryllium 

(μg/L)

Boron 

(μg/L)

Cadmium 

(μg/L)

Chromium 

(μg/L)

1 09/19/2006 0910 P <1.6 <0.20 <0.12 70 <0.06 360 <0.04 E0.07

2 09/19/2006 1220 P <1.6 <.20 <.12 53 <.06 160 .17 E.02

3 09/19/2006 1050 P E1.1 <.20 <.12 58 <.06 260 <.04 E.10

4 09/20/2006 0830 P <1.6 <.20 <.12 250 <.06 76 <.04 E.05

5 09/19/2006 1420 P E1.2 <.20 <.12 47 <.06 260 <.04 .15

6 09/20/2006 0950 P <1.6 <.20 <.12 280 <.06 95 <.04 .45

6 09/20/2006 0955 CR <1.6 <.20 <.12 280 <.06 99 <.04 E.08

7 09/20/2006 1215 P <1.6 <.20 <.12 61 <.06 95 <.04 E.06

8 10/11/2006 1125 P 3.4 E.10 <.12 82 <.06 240 <.40 <.12

9 09/21/2006 1110 P E1.2 <.20 .12 120 E.03 400 <.04 E.09

10 09/29/2006 1140 P <1.6 <.20 <.12 65 <.06 110 <.04 E.07

11 09/21/2006 1320 P E1.0 <.20 .46 140 <.06 67 <.04 E.06

12 09/21/2006 0925 P <1.6 <.20 <.12 130 <.06 320 <.04 E.05

13 09/22/2006 0915 P E.9 <.20 .79 98 <.06 73 <.04 E.06

14 09/29/2006 1330 P <1.6 <.20 .40 56 <.06 64 <.04 E.02

15 09/22/2006 1110 P <1.6 <.20 .17 52 <.06 150 <.04 E.04

16 05/29/2007 1550 P E1.0 <.06 <.12 110 <.06 79 <.04 <.12

17 12/13/2006 1130 P <1.6 <.06 <.12 40 <.06 150 <.04 <.12

18 05/29/2007 1330 P <1.6 <.06 .15 100 <.06 9.5 <.04 <.12

18 05/29/2007 1335 CR <1.6 <.06 .16 100 <.06 8.8 <.04 <.12

19 12/13/2006 0920 P E.8 <.06 <.12 100 <.06 57 <.04 <.12

20 05/30/2007 1000 P <1.6 <.06 .56 18 E.03 21 <.04 <.12

21 12/11/2006 1320 P <1.6 <.06 1.3 120 <.06 E7.1 <.04 <.12

22 05/30/2007 0800 P <1.6 <.06 .41 120 <.06 56 <.04 <.12

23 12/12/2006 1510 P <1.6 <.06 .48 130 <.06 12 <.04 <.12

23 12/12/2006 1515 CR <1.6 <.06 .51 130 <.06 12 <.04 <.12

24 12/11/2006 1610 P <1.6 <.06 <.12 48 <.06 9.5 <.04 <.12

25 12/12/2006 1120 P E1.0 E.03 .45 10 <.06 E7.9 <.04 E.07

26 12/12/2006 0820 P <1.6 <.06 .14 50 <.06 29 <.04 <.12

27 05/30/2007 1220 P E.9 E.03 .31 6.4 <.06 20 <.04 <.12

28 05/31/2007 0820 P E.9 E.04 <.12 8.9 <.06 21 .18 <.12

29 05/31/2007 1000 P E.9 E.04 .45 9.7 <.06 <8.0 .19 <.12

30 05/30/2007 1400 P E1.2 <.06 <.12 7.2 <.06 110 <.04 <.12

31 05/22/2007 1130 P <1.6 <.06 4.9 45 E.04 100 <.04 <.12

32 05/22/2007 1430 P E1.0 <.06 <.12 13 <.06 53 <.04 <.12

33 05/21/2007 1600 P E.8 <.06 <.12 180 <.06 960 <.04 E.06

34 05/23/2007 1300 P <1.6 <.06 <.12 14 <.06 54 <.04 <.12

34 05/23/2007 1305 CR E1.2 <.06 <.12 14 <.06 51 <.04 <.12

35 05/23/2007 0930 P <1.6 <.06 <.12 81 <.06 850 <.04 <.12

36 05/24/2007 0900 P 2.6 <.06 E.10 88 <.06 210 <.04 <.12

37 05/24/2007 1500 P E1.0 E.03 .37 50 <.06 E6.0 E.03 .45

38 05/24/2007 1300 P 8.9 <.06 <.12 22 <.06 160 <.04 <.12

39 06/01/2007 1010 P E1.6 <.06 <.12 4.2 <.06 1,400 <.04 <.12

40 06/01/2007 1140 P E1.1 <.06 <.12 11 <.06 610 <.04 <.12
56 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

Table 17. Results of selected trace element and stable isotope analyses of ground water from 40 water-supply wells completed 

in Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07.—

Continued

[μg/L, micrograms per liter; P, primary; CR, concurrent replicate; <, less than; E, estimated; d, del; permil, per thousand parts; C, carbon; H, hydrogen; O, 

oxygen; S, sulfur; Sr, strontium]

Map 

index 

number 

(fig. 4)

Date of 

sample 

collection 

(month/

day/year)

Time 

(24-hour)

Sample 

type

Cobalt 

(μg/L)

Copper 

(μg/L)

Iron 

(μg/L)

Lead 

(μg/L)

Lithium 

(μg/L)

Manganese 

(μg/L)

Mercury 

(μg/L)

Molybdenum 

(μg/L)

1 09/19/2006 0910 P <0.04 <1.6 130 <0.08 140 29 <0.01 <0.40

2 09/19/2006 1220 P <.04 <.40 15 .20 91 1.2 .01 <.40

3 09/19/2006 1050 P E.02 <1.2 18 E.04 140 2.7 <.01 <.40

4 09/20/2006 0830 P <.04 <.40 6.0 .18 64 1.2 <.01 <.40

5 09/19/2006 1420 P <.04 <1.2 560 <.08 120 14 <.01 <.40

6 09/20/2006 0950 P <.04 <.40 9.6 .13 91 4.8 <.01 <.40

6 09/20/2006 0955 CR <.04 <.40 6.0 .12 92 1.6 E.006 <.40

7 09/20/2006 1215 P <.04 <.40 76 .16 88 2.5 <.01 <.40

8 10/11/2006 1125 P <.04 <.40 52 <1.2 83 4.4 <.01 .59

9 09/21/2006 1110 P <.04 <.40 E3.0 <.08 110 1.9 <.01 <.40

10 09/29/2006 1140 P <.04 <.40 42 .09 47 1.7 <.01 <.40

11 09/21/2006 1320 P <.04 <.40 86 <.08 23 2.7 E.007 .84

12 09/21/2006 0925 P <.04 <.40 16 <.08 100 2.8 <.01 <.40

13 09/22/2006 0915 P .21 .74 49 .20 19 8.5 <.01 1.6

14 09/29/2006 1330 P <.04 <.40 100 .32 22 3.2 <.01 1.8

15 09/22/2006 1110 P <.04 <.40 84 <.08 69 3.7 <.01 1.0

16 05/29/2007 1550 P <.04 <.40 120 <.12 32 1.4 <.01 1.9

17 12/13/2006 1130 P <.04 <.40 120 <.12 46 2.4 .01 <.12

18 05/29/2007 1330 P <.04 1.1 <6.0 E.07 6.8 .33 <.01 4.7

18 05/29/2007 1335 CR <.04 .86 <6.0 E.06 6.3 .31 <.01 4.7

19 12/13/2006 0920 P <.04 <.40 60 <.12 17 1.2 .01 .52

20 05/30/2007 1000 P .75 E.21 3,200 <.12 81 95 <.01 .23

21 12/11/2006 1320 P <.04 <.40 1,800 <.12 1.6 68 .01 1.1

22 05/30/2007 0800 P <.04 E.34 14 E.11 30 1.8 <.01 1.8

23 12/12/2006 1510 P <.04 <.40 52 <.12 7.9 1.8 E.009 1.2

23 12/12/2006 1515 CR <.04 <.40 56 <.12 8.2 1.9 <.01 1.3

24 12/11/2006 1610 P <.04 <.40 32 <.12 5.0 .65 <.01 2.1

25 12/12/2006 1120 P <.04 <.40 E3.0 <.12 3.6 1.1 E.006 3.2

26 12/12/2006 0820 P <.04 <.40 9.0 <.12 15 1.8 E.006 2.5

27 05/30/2007 1220 P <.04 <.40 58 <.12 9.0 1.6 <.01 2.5

28 05/31/2007 0820 P <.04 <.40 7.0 <.12 11 .90 <.01 3.7

29 05/31/2007 1000 P <.04 E.31 33 <.12 E.86 .84 <.01 13

30 05/30/2007 1400 P <.04 <.40 14 <.12 55 .91 <.01 <.12

31 05/22/2007 1130 P .13 E.25 3,000 <.12 75 43 <.01 4.4

32 05/22/2007 1430 P <.04 <.40 31 <.12 16 1.4 <.01 3.6

33 05/21/2007 1600 P <.04 <.40 30 <.12 240 2.0 <.01 <.12

34 05/23/2007 1300 P <.04 <.40 38 <.12 22 1.5 E.007 E.09

34 05/23/2007 1305 CR <.04 <.40 39 <.12 21 1.5 E.009 E.10

35 05/23/2007 0930 P <.04 <.40 6.0 <.12 160 .69 <.01 <.12

36 05/24/2007 0900 P <.04 <.40 34 <.12 120 1.6 <.01 <.12

37 05/24/2007 1500 P .28 1.6 <6.0 E.06 1.0 .49 E.006 .44

38 05/24/2007 1300 P <.04 <.40 19 <.12 58 2.6 E.006 <.12

39 06/01/2007 1010 P <.04 E.30 20 E.07 170 2.7 <.01 .38

40 06/01/2007 1140 P <.04 E.37 E5.0 <.12 150 1.1 <.01 E.09
Supplemental Information 57

Table 17. Results of selected trace element and stable isotope analyses of ground water from 40 water-supply wells completed 

in Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07.—

Continued

[μg/L, micrograms per liter; P, primary; CR, concurrent replicate; <, less than; E, estimated; d, del; permil, per thousand parts; C, carbon; H, hydrogen; O, 

oxygen; S, sulfur; Sr, strontium]

Map 

index 

number 

(fig. 4)

Date of 

sample 

collection 

(month/day/

year)

Time 

(24-hour)

Sample 

type

Nickel 

(μg/L)

Selenium 

(μg/L)

Silver 

(μg/L)

Strontium 

(μg/L)

Thallium 

(μg/L)

Uranium 

(natural) 

(μg/L)

Vanadium 

(μg/L)

Zinc 

(μg/L)

1 09/19/2006 0910 P E0.04 <0.08 <0.8 1,400 <0.04 E0.03 <0.10 <0.60

2 09/19/2006 1220 P .10 <.08 <.2 1,400 <.04 E.03 <.10 <.60

3 09/19/2006 1050 P .15 <.08 <.2 1,500 <.04 .05 <.10 E.49

4 09/20/2006 0830 P E.05 <.08 <.2 620 <.04 E.03 <.10 .66

5 09/19/2006 1420 P .11 <.08 <.6 1,200 <.04 .06 <.10 <.60

6 09/20/2006 0950 P E.04 E.06 <.2 940 <.04 .04 <.10 <.60

6 09/20/2006 0955 CR E.03 .10 <.2 930 <.04 .05 <.10 <.60

7 09/20/2006 1215 P E.05 <.08 <.2 1,000 E.02 .11 <.10 <.60

8 10/11/2006 1125 P E.05 <.08 -- 1,100 <.40 .12 <.04 <.60

9 09/21/2006 1110 P E.04 <.08 <1.0 1,400 <.04 .17 <.10 .63

10 09/29/2006 1140 P .23 <.08 <.2 690 <.04 .53 <.10 9.3

11 09/21/2006 1320 P E.04 <.08 <.2 340 <.04 .32 <.10 .65

12 09/21/2006 0925 P E.03 <.08 <.6 1,200 <.04 .07 <.10 E.37

13 09/22/2006 0915 P .83 .38 <.2 160 <.04 .93 <.10 54

14 09/29/2006 1330 P .11 <.08 <.2 180 <.04 .49 <.10 4.0

15 09/22/2006 1110 P .06 <.08 <.2 650 <.04 .30 <.10 E.50

16 05/29/2007 1550 P E.03 <.08 <.1 290 <.04 .18 <.04 <.60

17 12/13/2006 1130 P .07 <.08 <.2 530 <.04 .14 <.04 <.60

18 05/29/2007 1330 P .06 E.04 <.1 70 <.04 .37 E.02 <.60

18 05/29/2007 1335 CR E.05 E.06 <.1 69 <.04 .40 E.02 <.60

19 12/13/2006 0920 P E.04 <.08 <.1 180 <.04 .17 <.04 E.31

20 05/30/2007 1000 P 2.4 E.07 <.1 190 <.04 .62 <.04 14

21 12/11/2006 1320 P E.04 <.08 <.1 56 <.04 .12 <.04 1.0

22 05/30/2007 0800 P .07 <.08 <.1 160 <.04 .61 <.04 6.7

23 12/12/2006 1510 P .08 <.08 <.1 71 <.04 .16 <.04 .74

23 12/12/2006 1515 CR .08 <.08 <.1 70 <.04 .17 <.04 .83

24 12/11/2006 1610 P E.04 <.08 <.1 52 <.04 .20 <.04 1.4

25 12/12/2006 1120 P .06 .90 <.1 52 E.02 .46 .07 E.47

26 12/12/2006 0820 P .06 <.08 <.1 160 <.04 .33 <.04 E.30

27 05/30/2007 1220 P .06 <.08 <.1 71 <.04 .22 <.04 .81

28 05/31/2007 0820 P .13 <.08 <.1 120 <.04 .10 <.04 1.3

29 05/31/2007 1000 P E.04 <.08 <.1 47 <.04 4.5 <.04 .87

30 05/30/2007 1400 P E.04 <.08 <.1 250 <.04 .07 E.03 E.35

31 05/22/2007 1130 P 1.5 <.08 <.1 410 <.04 .48 <.04 130

32 05/22/2007 1430 P .11 <.08 <.1 170 <.04 .12 E.02 3.4

33 05/21/2007 1600 P .11 E.05 <.1 1,700 <.04 <.04 .04 E.38

34 05/23/2007 1300 P E.03 <.08 <.1 180 <.04 .04 <.04 E.32

34 05/23/2007 1305 CR .08 <.08 <.1 180 <.04 .04 <.04 1.1

35 05/23/2007 0930 P <.06 <.08 <.1 600 <.04 E.03 .08 1.9

36 05/24/2007 0900 P .09 .14 <.1 1,400 <.04 E.03 .20 <.60

37 05/24/2007 1500 P 1.6 .85 <.1 83 <.04 1.4 .23 24

38 05/24/2007 1300 P E.03 <.08 <.1 570 <.04 .06 E.02 E.30

39 06/01/2007 1010 P .08 <.08 <.1 120 <.04 .05 <.04 .64

40 06/01/2007 1140 P .06 .64 <.1 650 <.04 <.04 .04 E.37
58 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

Table 17. Results of selected trace element and stable isotope analyses of ground water from 40 water-supply wells completed 

in Ozark aquifer, northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma, 2006–07.—

Continued

[μg/L, micrograms per liter; P, primary; CR, concurrent replicate; <, less than; E, estimated; d, del; permil, per thousand parts; C, carbon; H, hydrogen; O, 

oxygen; S, sulfur; Sr, strontium]

Map 

index 

number 

(fig. X)

Date of 

sample 

collection 

(month/day/

year)

Time 

(24-hour)

Sample 

type

d13C

(permil)

14C counting error 

(percent 

modern 

carbon)

14C, 

filtered 

(percent 

modern)

d2H 

(permil)

Tritium 

(picocuries per 

liter)

d18O 

(permil)

d34S, in 

sulfate 

(permil)

87Sr/86Sr 

ratio

1 09/19/2006 0910 P -- -- -- -- -- -- -- --

2 09/19/2006 1220 P -9.41 0.05 0 -39.1 0.37 -6.52 13.3 0.71424

3 09/19/2006 1050 P -- -- -- -- -- -- -- --

4 09/20/2006 0830 P -- -- -- -- -- -- -- --

5 09/19/2006 1420 P -- -- -- -- -- -- -- --

6 09/20/2006 0950 P -9.10 .05 .12 -40.3 1.0 -6.73 20.1 .71378

6 09/20/2006 0955 CR -9.21 .05 .09 -40.4 .65 -6.67 20.2 .71379

7 09/20/2006 1215 P -- -- -- -- -- -- -- --

8 10/11/2006 1125 P -- -- -- -- -- -- -- --

9 09/21/2006 1110 P -- -- -- -- -- -- -- --

10 09/29/2006 1140 P -- -- -- -- -- -- -- --

11 09/21/2006 1320 P -- -- -- -- -- -- -- --

12 09/21/2006 0925 P -8.66 .05 .05 -39.0 .03 -6.55 16.7 .71532

13 09/22/2006 0915 P -8.37 .13 16 -37.4 4.7 -6.34 -.09 .71248

14 09/29/2006 1330 P -- -- -- -- -- -- -- --

15 09/22/2006 1110 P -- -- -- -- -- -- -- --

16 05/29/2007 1550 P -- -- -- -- -- -- -- --

17 12/13/2006 1130 P -7.45 .05 .06 -40.7 .06 -6.69 21.0 .71375

18 05/29/2007 1330 P -- -- -- -- -- -- -- --

18 05/29/2007 1335 CR -- -- -- -- -- -- -- --

19 12/13/2006 0920 P -7.14 .07 5.3 -39.9 .69 -6.76 4.85 .71177

20 05/30/2007 1000 P -- -- -- -- -- -- -- --

21 12/11/2006 1320 P -9.71 .08 5.7 -36.1 .31 -6.21 9.68 .71002

22 05/30/2007 0800 P -- -- -- -- -- -- -- --

23 12/12/2006 1510 P -6.95 .05 .36 -39.1 .42 -6.52 -8.37 .71095

23 12/12/2006 1515 CR -6.78 .05 .45 -39.3 .22 -6.56 -8.27 .71095

24 12/11/2006 1610 P -7.74 .05 .18 -40.5 .26 -6.90 -14.9 .71090

25 12/12/2006 1120 P -7.41 .07 4.3 -40.6 .23 -6.52 -4.33 .71061

26 12/12/2006 0820 P -8.85 .09 10 -38.4 .32 -6.49 -2.01 .71079

27 05/30/2007 1220 P -- -- -- -- -- -- -- --

28 05/31/2007 0820 P -- -- -- -- -- -- -- --

29 05/31/2007 1000 P -- -- -- -- -- -- -- --

30 05/30/2007 1400 P -- -- -- -- -- -- -- --

31 05/22/2007 1130 P -- -- -- -- -- -- -- --

32 05/22/2007 1430 P -- -- -- -- -- -- -- --

33 05/21/2007 1600 P -- -- -- -- -- -- -- --

34 05/23/2007 1300 P -- -- -- -- -- -- -- --

34 05/23/2007 1305 CR -- -- -- -- -- -- -- --

35 05/23/2007 0930 P -- -- -- -- -- -- -- --

36 05/24/2007 0900 P -- -- -- -- -- -- -- --

37 05/24/2007 1500 P -- -- -- -- -- -- -- --

38 05/24/2007 1300 P -- -- -- -- -- -- -- --

39 06/01/2007 1010 P -- -- -- -- -- -- -- --

40 06/01/2007 1140 P -- -- -- -- -- -- -- --
Supplemental Information 59

Table 18. Results of measurements or analysis of physical properties and chemical analyses of depth-dependent groundwater samples collected under pumping conditions from Pittsburg, Kansas, city well 10, August 13–14, 2007. 

[μS/cm, microsiemens per centimeter; oC, degrees Celsius; mg/L, milligrams per liter; NTU, nephelometric turbidity units; mV, millivolts; SHE, 

standard hydrogen electrode; CaCO3, calcium carbonate; E, estimated; <, less than; permil, per thousand parts; pCi/L, picocuries per liter; C, carbon; 

pct, percent; δ, del; H, hydrogen; Sr, strontium; S, sulfur]

Constituent

(unit of measurement)

Sampling depth, in feet below land surface

Well head 487 687 787 877 937 1030

Physical properties

Specific conductance (μS/cm) 898 913 914 926 996 981 848

pH (standard units) 7.22 7.41 7.25 7.37 7.37 7.28 7.65

Water temperature (°C) 21.1 --- --- --- --- --- ---

Dissolved oxygen (mg/L) 5.4 --- --- --- --- --- ---

Turbidity (NTU) 0.39 0.67 0.46 0.74 0.59 1.2 0.64

Oxidation-reduction (redox)

potential, raw (mV)

-233 -220 -182 -208 -211 --- -162

Oxidation-reduction (redox)

potential, SHE (mV)

-30 -30 10 -20 -20 --- 30

Alkalinity, as CaCO3 260 260 260 260 250 250 240

Dissolved solids and major ions, in milligrams per liter

Dissolved solids 510 500 500 510 540 550 430

Calcium 67 68 69 71 71 74 69

Magnesium 29 29 29 30 30 31 31

Sodium 77 77 76 77 84 84 60

Potassium 5.6 5.8 5.9 5.9 5.6 5.9 4.5

Bicarbonate 310 320 320 320 300 310 290

Carbonate .2 .2 .2 .1 .8 .3 0

Sulfate 78 72 73 78 73 74 79

Chloride 84 83 82 83 110 110 54

Fluoride .65 .64 .65 .63 .62 .64 .56

Bromide .24 .24 .24 .25 .29 .30 .17

Silica 10 10 11 10 11 11 10

Nutrients, in milligrams per liter

Nitrite, as nitrogen <.002 <.002 <.006 <.002 <.002 <.002 <.002

Nitrite plus nitrate, as nitrogen <.06 <.06 <.06 <.06 <.06 <.06 <.06

Ammonia, as nitrogen .21 .20 .20 .20 .18 .18 .14

Total nitrogen .18 .20 .22 .20 .22 .21 .20

Phosphorus <.006 <.006 <.006 <.006 <.006 <.006 <.006

Orthophosphate, as phosphorus E.004 E.005 E.003 E.004 E.005 E.004 E.005

Trace elements, in micrograms per liter

Aluminum E1.4 5.0 E1.2 1.8 3.7 3.1 15

Antimony <.06 <.06 <.06 <.06 <.06 <.06 <.06

Arsenic <.12 <.12 <.12 <.12 <.12 <.12 <.12

Barium 130 130 130 120 96 94 44
60 Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

Table 18. Results of measurements or analysis of physical properties and chemical analyses of depth-dependent groundwater samples collected under pumping conditions from Pittsburg, Kansas, city well 10, August 13–14, 2007.—Continued

[μS/cm, microsiemens per centimeter; oC, degrees Celsius; mg/L, milligrams per liter; NTU, nephelometric turbidity units; mV, millivolts; SHE, 

standard hydrogen electrode; CaCO3, calcium carbonate; E, estimated; <, less than; permil, per thousand parts; pCi/L, picocuries per liter; C, carbon; 

pct, percent; δ, del; H, hydrogen; Sr, strontium; S, sulfur]

Constituent

(unit of measurement)

Sampling depth, in feet below land surface

Well head 487 687 787 877 937 1030

Trace elements, in micrograms per liter—Continued

Beryllium <0.06 <0.06 <0.06 <0.06 <0.06 <0.06 <0.06

Boron 170 160 170 160 150 150 130

Cadmium <.04 <.04 <.04 <.04 <.04 <.04 <.04

Chromium <.12 E.06 E.06 <.12 E.08 E.10 E.08

Cobalt E.03 E.03 E.03 E.03 E.03 E.03 E.03

Copper <.40 <.40 E.23 <.40 E.20 .59 E.26

Iron E6.0 6.0 E4.0 E5.0 E6.0 E3.0 100

Lead <.12 <.12 E.06 E.10 E.06 0.12 E.07

Lithium 94 88 86 95 90 93 81

Manganese 1.5 1.7 1.5 1.3 1.8 1.8 2.7

Mercury E.01 <.01 <.01 <.01 E.007 <.01 E.007

Molybenum <.12 <.12 <.12 <.12 <.12 <.12 <.12

Nickel .32 .50 .47 .48 .54 .67 .59

Selenium <.08 <.08 <.08 <.08 <.08 <.08 <.08

Silver <.1 <.1 <.1 <.1 <.1 <.1 <.1

Strontium 940 890 900 940 880 670 860

Thallium <.04 <.04 <.04 <.04 <.04 <.04 <.04

Uranium .04 .04 .04 .04 .04 .04 .43

Vanadium .09 .11 .10 .10 .14 .12 .08

Zinc <.60 E.30 .77 1.2 .70 3.5 .62

Isotopes

δ13C (permil) -9.08 --- --- --- --- -8.54 ---

14C counting error (pct modern) .05 --- --- --- --- .05 ---

14C (pct modern) 0 --- --- --- --- .6 ---

δ2H (permil) -42.0 --- --- --- --- -41.4 ---

Tritium (pCi/L) --- --- --- --- --- --- ---

δ180 (permil) -6.76 --- --- --- --- -6.74 ---

δ34S (permil) 14.0 --- --- --- --- 13.3 ---

87Sr/86Sr (ratio) .71363 --- --- --- --- .71374 ---
Publishing support provided by:

Rolla Publishing Service Center

For more information concerning this publication, contact:

Director, USGS Kansas Water Science Center

4821 Quail Crest Place

Lawrence, KS 66049

(785) 842–9909

Or visit the Kansas Water Science Center Web site at:

http://ks.water.usgs.gov
Pope

—Quality Characteristics of Ground Water in the Ozark Aquifer of Arkansas, Kansas, Missouri, and Oklahoma, 2006–07

—Scientific Investigations Report 2009–5093

KANSAS

KANSAS

OKLAHOMA

OKLAHOMA

ARKANSAS

ARKANSAS

MISSOURI

MISSOURI

MISSOURI

ILLINOIS

Boston Mountains 

Arkansas Valley

Springfield

Plateau

Osage

Plains

Salem Plateau

St. Francois

Mountains

Mississippi Alluvial Plain

O Z A R K P L A T E A U S

C O A S T A L

P L A I N

C E N T R A L

L O W L A N D

O U A C H I T A

Jasper

County

Barry

County

Washington

County

Fayetteville

Joplin

Pittsburg

Chanute

Miami

Springfiled

Ottawa

County

MISSOURI

KANSAS

OKLAHOMA

ARKANSAS

Index map

Tri-State Mining

District