U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2012–5253

Revised March 2013

Prepared in cooperation with the Kickapoo Tribe of Oklahoma

Groundwater Quality and the Relation Between

pH Values and Occurrence of Trace Elements and 

Radionuclides in Water Samples Collected from

Private Wells in Part of the Kickapoo Tribe of Oklahoma 

Jurisdictional Area, Central Oklahoma, 2011
Cover:

Background, View of the terrace deposits from the alluvium in the central Oklahoma study area, December 2012.

Right, U.S. Geological Survey personnel measuring water pH at a private well in the central Oklahoma study area, August 2011.
Groundwater Quality and the Relation Between 

pH Values and Occurrence of Trace Elements and 

Radionuclides in Water Samples Collected from Private 

Wells in Part of the Kickapoo Tribe of Oklahoma 

Jurisdictional Area, Central Oklahoma, 2011

By Carol J. Becker

Prepared in cooperation with the Kickapoo Tribe of Oklahoma

Scientific Investigations Report 2012–5253

Revised March 2013

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: 2013

This and other USGS information products are available at http://store.usgs.gov/

U.S. Geological Survey

Box 25286, Denver Federal Center

Denver, CO 80225

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:

Becker, C.J., 2013, Groundwater quality and the relation between pH values and occurrence of trace elements and 

radionuclides in water samples collected from private wells in part of the Kickapoo Tribe of Oklahoma Jurisdictional 

Area, central Oklahoma, 2011: U.S. Geological Survey Scientific Investigations Report 2012–5253, 47 p., 5 apps. 

(Revised March 2013.)
iii

Acknowledgments

The author thanks Darren Shields, Kara Davis, and Richard Ketakeah of the Kickapoo Tribe of 

Oklahoma for their assistance with this project. Gratitude also is expressed to the many well 

owners who graciously allowed the author to access their wells for collection of water samples.

The author would like to thank U.S. Geological Survey (USGS) personnel Zoltan Szabo and Lisa 

Senior for reviewing the report draft and providing constructive comments. Mr. Szabo’s assistance with interpreting the radionuclide quality-control sample analyses was essential. The 

author would also like to thank USGS personnel Ann Mullin at the USGS National Water Quality 

Laboratory for her assistance with analysis and interpretation of the radionuclide samples.
iv

Contents

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

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

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

Health Information on Radionuclides and Radioactivity................................................................2

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

Previous Studies in Oklahoma............................................................................................................6

Methods...........................................................................................................................................................7

Field Methods......................................................................................................................................10

Laboratory Analysis............................................................................................................................11

Reporting Results of Analysis of Radionuclides............................................................................11

Quality-Assurance Procedures........................................................................................................12

Groundwater Quality ...................................................................................................................................12

pH Values .............................................................................................................................................12

Major Ions and Water Types.............................................................................................................20

Trace Elements....................................................................................................................................22

Radionuclides......................................................................................................................................23

Relation Between pH and Occurrence of Trace Elements and Radionuclides.................................27

Summary........................................................................................................................................................27

References....................................................................................................................................................28

Appendix 1. Water-property measurements and concentrations of major ions

measured in water samples collected from 20 private wells in part of the

Kickapoo Tribe of Oklahoma Jurisdictional Area, central Oklahoma, 2011 .................................34

Appendix 2. Trace-element concentrations measured in water samples

collected from 20 private wells in part of the Kickapoo Tribe of Oklahoma

Jurisdictional Area, central Oklahoma, 2011.....................................................................................36

Appendix 3. Radionuclide concentrations measured in water samples

collected from 20 private wells in part of the Kickapoo Tribe of Oklahoma

Jurisdictional Area, central Oklahoma, 2011.....................................................................................38

Appendix 4. Analytical relative percent difference for concentrations

of major ions and trace elements (including uranium) in quality-control samples,

in addition to equipment-blank results, for water samples collected from

20 private wells in part of the Kickapoo Tribe of Oklahoma Jurisdictional Area,

central Oklahoma, 2011.........................................................................................................................44

Appendix 5. Analytical relative percent difference for concentrations of

radionuclides (not including uranium) in quality-control samples for

water samples collected from 20 private wells in part of the Kickapoo Tribe

of Oklahoma Jurisdictional Area, central Oklahoma, 2011 .............................................................46
v

Figures

1. Map showing surficial geology and location of the Central Oklahoma

aquifer and study area in the Kickapoo Tribe of Oklahoma

Jurisdictional Area, central Oklahoma .....................................................................................3

2. Diagram showing uranium-238 and thorium-232 radioactive decay series .......................4

3. Map showing land surface contours, well locations, and

pH measurements of water from private wells in part of the

Kickapoo Tribe of Oklahoma Jurisdictional Area, central Oklahoma, 2011 ........................8

4. Graph showing number of wells and pH values measured in water collected

from 59 private wells in part of the Kickapoo Tribe of

Oklahoma Jurisdictional Area, central Oklahoma, 2011 ......................................................18

5. Maps showing historical water-quality data from wells in the

Kickapoo Tribe of Oklahoma Jurisdictional Area, central Oklahoma.

A, Historical pH values in groundwater (1954–2008). B, Historical pH

and analyses of arsenic in groundwater (1977–2008). C, Historical pH and

analyses of uranium in groundwater (1977–2008).................................................................19

6. Graphs showing relation of land surface altitude of wells

to measurements of A, pH and B, specific conductance of water

collected from 59 private wells in part of the Kickapoo Tribe of

Oklahoma Jurisdictional Area, central Oklahoma, 2011 ......................................................20

7. Piper diagram showing water types and percentages of cations

and anions composing water samples collected from 20 private

wells in part of the Kickapoo Tribe of Oklahoma Jurisdictional Area,

central Oklahoma, 2011..............................................................................................................21

8. Graphs showing concentrations of A, arsenic, B, chromium, and

C, selenium in relation to pH in water samples collected from

20 private wells in part of the the Kickapoo Tribe of Oklahoma

Jurisdictional Area, central Oklahoma, 2011 .........................................................................22

9. Graphs showing concentrations of selected trace elements

in water samples collected from 20 private wells in part of the

Kickapoo Tribe of Oklahoma Jurisdictional Area, central Oklahoma, 2011 ......................24

10. Graphs showing concentrations of A, uranium, B, gross alpha-particle activity,

and C, radon-222 in relation to pH and D, uranium in relation to

bicarbonate in water samples collected from 20 private wells for

this study (2011) and in historical analyses in the Kickapoo Tribe

of Oklahoma Jurisdictional Area, central Oklahoma............................................................25

11. Graph showing concentrations of uranium related to

gross alpha-particle activity at 72 hours after collection in

water samples from 20 private wells for this study (2011) and in

historical analyses in the Kickapoo Tribe of Oklahoma Jurisdictional

Area, central Oklahoma.............................................................................................................26
vi

Tables

1. Maximum Contaminant Levels, method references, and

highest minimum laboratory reporting levels of water properties,

major ions, trace elements, and radionuclides measured in water samples

collected from 20 private wells in part of the Kickapoo Tribe of Oklahoma

Jurisdictional Area, central Oklahoma, 2011 ...........................................................................9

2. Field measurements, well information, and water type of water

collected from private wells in part of the Kickapoo Tribe of

Oklahoma Jurisdictional Area, central Oklahoma, 2011 ......................................................13

3. Statistical summaries of pH, specific conductance, and

concentrations of selected trace elements and radionuclides

in water samples collected from 20 private wells for this study (2011)

and in historical (1954–2008) analyses in the Kickapoo Tribe of

Oklahoma Jurisdictional Area, central Oklahoma ................................................................15

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

Volume

gallon (gal) 3.785 liter (L) 

gallon (gal) 0.003785 cubic meter (m3) 

gallon (gal)

ounce, fluid (fl. oz)

ounce, fluid (fl. oz)

3.785

0.02957

29.574

cubic decimeter (dm3)

liter (L)

milliliter (mL) 

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 1988 

(NAVD 88).

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

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

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

25 °C).

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

or in micrograms per liter (μg/L).

Concentrations of radionuclides in water are given in picocuries per liter (pCi/L).
vii

Laboratory reporting level (LRL): The LRL is generally equal to twice the yearly determined longterm method detection level (LT–MDL). The LRL controls false negative error. The probability 

of falsely reporting a nondetection for a sample that contained an analyte at a concentration 

equal to or greater than the LRL is predicted to be less than or equal to 1 percent. The value of 

the LRL will be reported with a “less than” remark code for samples in which the analyte was 

not detected. The National Water Quality Laboratory collects quality-control data from selected 

analytical methods on a continuing basis to determine LT–MDLs and to establish LRLs. These 

values are reevaluated annually based on the most current quality-control data, and therefore, 

may change (Childress and others, 1999).

Sample-specific critical level (ssLc): The critical level is the lowest measured concentration 

that is statistically different from the instrument background or analytical blank, and it serves as 

the detection threshold for deciding whether the radionuclide is present in a sample (McCurdy 

and others, 2008).
viii
Groundwater Quality and the Relation Between pH Values and 

Occurrence of Trace Elements and Radionuclides in Water Samples 

Collected from Private Wells in Part of the Kickapoo Tribe of Oklahoma 

Jurisdictional Area, Central Oklahoma, 2011

By Carol J. Becker

Abstract 

From 1999 to 2007, the Indian Health Service reported 

that gross alpha-particle activities and concentrations of 

uranium exceeded the Maximum Contaminant Levels 

for public drinking-water supplies in water samples from 

six private wells and two test wells in a rural residential 

neighborhood in the Kickapoo Tribe of Oklahoma 

Jurisdictional Area, in central Oklahoma. Residents in this 

rural area use groundwater from Quaternary-aged terrace 

deposits and the Permian-aged Garber–Wellington aquifer 

for domestic purposes. Uranium and other trace elements, 

specifically arsenic, chromium, and selenium, occur naturally 

in rocks composing the Garber–Wellington aquifer and in 

low concentrations in groundwater throughout its extent. 

Previous studies have shown that pH values above 8.0 from 

cation-exchange processes in the aquifer cause selected metals 

such as arsenic, chromium, selenium, and uranium to desorb 

(if present) from mineral surfaces and become mobile in 

water. On the basis of this information, the U.S. Geological 

Survey, in cooperation with the Kickapoo Tribe of Oklahoma, 

conducted a study in 2011 to describe the occurrence of 

selected trace elements and radionuclides in groundwater and 

to determine if pH could be used as a surrogate for laboratory 

analysis to quickly and inexpensively identify wells that 

might contain high concentrations of uranium and other 

trace elements. 

The pH and specific conductance of groundwater 

from 59 private wells were measured in the field in an 

area of about 18 square miles in Lincoln and Pottawatomie 

Counties. Twenty of the 59 wells also were sampled for 

dissolved concentrations of major ions, trace elements, gross 

alpha-particle and gross beta-particle activities, uranium, 

radium-226, radium-228, and radon-222 gas.

Arsenic concentrations exceeded the Maximum 

Contaminant Level of 10 micrograms per liter in one sample 

having a concentration of 24.7 micrograms per liter. Selenium 

concentrations exceeded the Maximum Contaminant Level of 

50 micrograms per liter in one sample having a concentration 

of 147 micrograms per liter. Both samples had alkaline pH 

values, 8.0 and 8.4, respectively. Uranium concentrations 

ranged from 0.02 to 383 micrograms per liter with 5 of 

20 samples exceeding the Maximum Contaminant Level 

of 30 micrograms per liter; the five wells with uranium 

concentrations exceeding 30 micrograms per liter had pH 

values ranging from 8.0 to 8.5. Concentrations of uranium and 

radon-222 and gross alpha-particle activity showed a positive 

relation to pH, with the highest concentrations and activity in 

samples having pH values of 8.0 or above. The groundwater 

samples contained dissolved oxygen and high concentrations 

of bicarbonate; these characteristics are also factors in 

increasing uranium solubility.

Concentrations of radium-226 and radium-228 

(combined) ranged from 0.03 to 1.7 picocuries per liter, 

with a median concentration of 0.45 picocuries per liter for 

all samples. Radon-222 concentrations ranged from 95 to 

3,600 picocuries per liter with a median concentration of 

261 picocuries per liter. Eight samples having pH values 

ranging from 8.0 to 8.7 exceeded the proposed Maximum 

Contaminant Level of 300 picocuries per liter for radon-222. 

Eight samples exceeded the 15 picocuries per liter Maximum 

Contaminant Level for gross alpha-particle activity at 72 

hours (after sample collection) and at 30 days (after the initial 

count); those samples had pH values ranging from 8.0 to 8.5. 

Gross beta-particle activity increased in 15 of 21 samples 

during the interval from 72 hours to 30 days. The increase in 

gross beta-particle activity over time probably was caused 

by the ingrowth and decay of uranium daughter products that 

emit beta particles.

Water-quality data collected for this study indicate that 

pH values above 8.0 are associated with potentially high 

concentrations of uranium and radon-222 and high gross 

alpha-particle activity in the study area. High pH values also 

are associated with potentially high concentrations of arsenic, 

chromium, and selenium in groundwater when these elements 

occur in the aquifer matrix along groundwater-flow paths.
2 Groundwater Quality in Water Samples Collected in Part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, 2011

Introduction

From 1999 to 2007, the Indian Health Service reported 

that gross alpha-particle activities and concentrations of 

uranium exceeded the Maximum Contaminant Levels (MCL) 

for public drinking-water supplies in water samples from 

six private wells and two test wells in a rural residential 

neighborhood in the Kickapoo Tribe of Oklahoma 

Jurisdictional Area, in central Oklahoma (D. Shields, Director, 

Department of Environmental Programs, Kickapoo Tribe of 

Oklahoma, written commun., 2010). Gross alpha-particle 

activities in water samples from the private wells were 

reported to range from 20 to 789 picocuries per liter (pCi/L), 

exceeding the MCL of 15 pCi/L and two of the six wells 

contained uranium concentrations of 46 and 47 micrograms 

per liter (μg/L), exceeding the MCL of 30 μg/L (U.S. 

Environmental Protection Agency, 2009a). Water samples 

from two test wells drilled in the neighborhood to obtain 

additional water-quality data contained gross alpha-particle 

activities of 41 and 58 pCi/L and uranium concentrations 

of 38 to 51 μg/L. A water sample collected from one of the 

six private wells by the U.S. Geological Survey (USGS) in 

2008 contained a uranium concentration of 1,500 μg/L. The 

pH values of that sample and water from the two test wells 

were alkaline at 8.2, 8.6, and 8.9 standard units, respectively. 

These private wells have been subsequently destroyed but 

because the quality of water from private wells is not routinely 

measured, other well owners in the area may not be aware of 

water-quality problems that can increase risks to their health.

Residents in this rural area use groundwater from 

Quaternary-aged terrace deposits and the Permian-aged 

Garber–Wellington aquifer for domestic purposes. The 

Garber–Wellington aquifer is part of a complex of sandstone, 

siltstone, and mudstone rocks, referred to as the “Central 

Oklahoma aquifer,” that underlies about 2,890 square miles 

of central Oklahoma (fig. 1) and is the primary water supply 

for municipal, domestic, industrial, and agricultural needs 

(Tortorelli, 2009). Uranium, arsenic, chromium, and selenium 

occur naturally in rocks in the Garber Sandstone and the 

Wellington Formation (that compose the Garber–Wellington 

aquifer) and in low concentrations in groundwater throughout 

the extent of those units (Christenson and Havens, 1998; 

Schlottmann and others, 1998). In some areas, concentrations 

of these trace elements exceed the MCLs and have created 

challenges for public water-supply systems that must provide 

water below regulated concentration levels to the public 

(Schlottmann and others, 1998). In central Oklahoma, 

arsenic is the trace element of highest concern because its 

occurrence in concentrations above drinking-water standards 

affects more public-water supply systems than does any other 

inorganic constituent in groundwater (Schlottmann and others, 

1998; Robertson, 1989; Parkhurst and others, 1996; Smith 

and others, 2009). The extent and occurrence of elevated 

concentrations of uranium and other trace elements in private 

well water are relatively unknown in the Kickapoo Tribe of 

Oklahoma Jurisdictional Area because of the relative lack of 

water-quality data from private wells compared to water used 

for public supply.

On the basis of these previously collected data, the 

USGS, in cooperation with the Kickapoo Tribe of Oklahoma, 

sampled groundwater in an area of about 18 square miles in 

Lincoln and Pottawatomie counties in the Kickapoo Tribe of 

Oklahoma Jurisdictional Area, to describe the occurrence of 

selected trace elements and radionuclides in groundwater and 

to determine if pH could be used as a surrogate for more costly 

analyses to quickly and inexpensively identify groundwater 

that might contain high concentrations of selected trace 

elements and radionuclides. Data described in this report 

may be useful for making decisions about future well-drilling 

activities and for prioritizing areas for water-quality testing, 

water treatment, water use, and other planning purposes. 

Purpose and Scope

This report describes the results of a study conducted in 

2011 to describe groundwater quality and the relation between 

pH values and the occurrence of selected trace elements and 

radionuclides in samples collected from private wells in an 

area of about 18 square miles in Lincoln and Pottawatomie 

Counties in the Kickapoo Tribe of Oklahoma Jurisdictional 

Area in central Oklahoma (fig. 1). Field measurements of pH 

and specific conductance of water from 59 private wells are 

summarized, and the results of chemical analyses of water 

from 20 of the 59 wells selected for sampling are presented 

and summarized. Historical pH values and concentrations 

of arsenic and uranium in the Kickapoo Tribe of Oklahoma 

Jurisdictional Area are shown on maps and graphs for 

comparison to collected samples. These data were retrieved 

from the USGS National Water Information System database 

on December 1, 2011 (U.S. Geological Survey, 2012).

Health Information on Radionuclides

and Radioactivity

Uranium-238 and thorium-232 are the most common 

naturally occurring radioactive elements and are found in 

varying amounts in soils, rocks, and water (Zapecza and 

Szabo, 1988; Focazio and others, 2001). Both of these 

radionuclides are unstable and undergo a decay process 

forming progeny (“daughter”) radionuclides to stabilize the 

atomic configuration; those daughter radionuclides undergo 

further radioactive decay (fig. 2). Some elements have multiple 

isotopes with each isotope having the same number of protons 

and electrons but differing numbers of neutrons. The different 

number of neutrons gives each isotope of an element a 

different mass number, which affects the nucleus stability and 

chemical bond strength. For example, there are 17 isotopes 

of uranium, of which 3 are naturally occurring (uranium-238, 

uranium-235, and uranium-234). All uranium isotopes are 

radioactive, and most decay in fractions of a second.
Introduction 3

No rthCanadi a n River

LINCOLN

COUNTY

LOGAN

COUNTY

OKLAHOMA

COUNTY

MCCLAIN

COUNTY

POTTAWATOMIE

COUNTY

CLEVELAND

COUNTY

-97°40' -97°20' -97° -96°40' -96°20'

36°

35°40'

35°20'

35°

CENTRAL OKLAHOMA AQUIFER

Oklahoma

Study area

Figure 1. Surficial geology and location of the Central Oklahoma aquifer and study area in the Kickapoo Tribe 

of Oklahoma Jurisdictional Areacentral Okla2011

Kickapoo Tribe of Oklahoma 

Jurisdictional Area

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

Albers Equal Area Conic projection, North American Datum 1983

Geology from Lindberg (1987) and Bingham and Moore (1975)

Alluvium

Garber Sandstone

Wellington Formation

Chase, Council Grove, and Admire 

 Groups (undifferentiated)

QUATERNARY PERMIAN

Hennessey Group

Terrace deposits

EXPLANATION 0 10 20 MILES

0 10 20 KILOMETERS

Figure 1. Surficial geology and location of the Central Oklahoma aquifer and study area in the Kickapoo Tribe of Oklahoma 

Jurisdictional Area, central Oklahoma.
4 Groundwater Quality in Water Samples Collected in Part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, 2011

Uranium

Protactinium

Thorium

Radium

Radon

Polonium

Bismuth

Lead

Thorium

Actinium

Radium

Radon

Polonium

Bismuth

Lead

Thallium

Th-234

24.1 d

Pa-234

1.17 m

U-234

2.46x10 5y

Th-230

7.5x10 4y

Ra-226

1,601 y

Rn-222

3.82 d

Po-218

3.1 m

Pb-214

26.8 m

Bi-214

19.9 m

Po-214

1.6x10 -6s

Pb-210

22.3 y

Bi-210

5.0 d

Po-210

138.4 d

Pb-206

stable

Uranium-238 series

Thorium-232 series

U-238

4.47x10 9y

Ra-228

5.75 y

Ac-228

6.13 h

Th-228

1.91 y

Ra-224

3.63 d

Rn-220

55.6 s

Po-216

0.15 s

Pb-212

10.64 h

Bi-212

60.5 m

Po-212

2.99x10 -7s

Pb-208

Stable

Tl-208

3.1 m

Th-232

1.4x10 10y

Figure 2. Uranium-238 and thorium-232 radioactive decay series. (Modified from Hall and others, 1985).

EXPLANATION

Alpha particles

Beta particles

Radionuclides of interest in this study are shaded;

times shown are half lives: y, years; d, days;

h, hours; m, minutes; s, seconds 

Figure 2. Uranium-238 and thorium-232 radioactive decay series.
Introduction 5

The uranium-238 isotope is the most stable (long-lived) 

uranium isotope, having a half-life of about 4.5 billion 

years; as a result it composes 99.4 percent of the uranium 

in the Earth (a half-life is the time required for a radioactive 

element to decay to half of the initial amount). This isotope 

is sufficiently abundant to be detected by relatively common 

chemical analyses. 

The radioactive decay process releases ionizing radiation, 

which is composed of alpha particles, beta particles, or 

gamma rays. Alpha particles do not penetrate the skin and are 

hazardous to internal organs only when inhaled or ingested 

(U.S. Environmental Protection Agency, 1999). Beta particles 

can penetrate the skin, and strong sources can redden or even 

injure tissue; however, the greatest damage occurs through 

inhalation or ingestion (U.S. Environmental Protection 

Agency, 2012a). The greatest risk to human health in general 

comes from a lifetime of exposure to radionuclides (U.S. 

Environmental Protection Agency, 1999); health hazards from 

short-term exposure generally are negligible. Drinking water 

MCLs for exposure to radioactivity are set at a level of about 

a 1 in 10,000 risk of developing a fatal cancer over a lifetime 

of 70 years when consuming 2 liters of water per day (U.S. 

Environmental Protection Agency, 2000).

Uranium as the isotope uranium-238 decays through 

intermediate decay products to radium-226 (half-life of 

1,601 years), which decays to radon-222 gas (half-life of 

3.82 days) (fig. 2). Uranium isotopes, radium-226, and 

radon-222 are primarily alpha-particle emitters but have 

short-lived intermediate progenies created during the decay 

process that emit beta particles (Zapecza and Szabo, 1988). 

The main health effects from long-term ingestion of uranium 

are kidney damage and an increase in the risk of cancer 

(U.S. Environmental Protection Agency, 2011). Uranium 

has an MCL in public drinking-water supplies of 30 μg/L 

(U.S. Environmental Protection Agency, 2000).

Radium-228, a daughter product of the most abundant 

isotope of thorium-232, has a half-life of 5.75 years and 

emits beta particles during the decay process. Health effects 

from long-term exposure to radium isotopes by ingestion are 

an increase in the risk of cancer and diseases that affect the 

formation of blood such as leukemia and aplastic anemia (U.S. 

Environmental Protection Agency, 2010a). Radium-226 and 

radium-228 in public drinking-water supplies have a combined 

MCL of 5 pCi/L.

Radon-222 is the most abundant and longest lived radon 

isotope. Radon occurs as a gas that can be dissolved in water 

and ingested, but inhalation is the primary method of exposing 

the body to radiation (U.S. Environmental Protection Agency, 

2010b). Radon gas dissolved in water can be released indoors 

when one showers or washes, but the main source of radon 

emission to indoor air is the decay of uranium in soils and 

rocks underlying homes and buildings (U.S. Environmental 

Protection Agency, 2010b). Radon is the second leading 

cause of lung cancer in the United States and is considered to 

be a serious potential health problem (Commission on Life 

Sciences, 1999). As of 2012, there was no MCL for radon in 

public drinking-water supplies. The MCL of 4,000 pCi/L for 

radon in public water-supply systems has been proposed by 

the U.S. Environmental Protection Agency (EPA) if statewide 

Multimedia Mitigation programs are established to address 

radon in indoor air. A second option is a MCL of 300 pCi/L 

for systems that choose not to develop Multimedia Mitigation 

programs (U.S. Environmental Protection Agency, 2012b). 

Study Area Description

The Kickapoo Tribe of Oklahoma Jurisdictional Area 

encompasses about 317 square miles in parts of Lincoln, 

Oklahoma, and Pottawatomie Counties (fig. 1). The study 

area was located in the south-central portion of the Kickapoo 

Tribe of Oklahoma Jurisdictional Area over an area of about 

18 square miles. The area is mostly rural with households 

dependent on wells for water supply and septic systems for 

sewage. Land cover is predominately grassland (70 percent) 

with about 10 percent used for hay and pasture and 10 percent 

for cultivated crops, which are located on the alluvium (Fry 

and others, 2011). 

Private wells in the study area range in depth from less 

than 100 feet (ft) to generally not more than 200 ft below 

land surface and obtain water from Quaternary-aged terrace 

deposits and the underlying Permian-aged Garber–Wellington 

aquifer (Oklahoma Water Resources Board, 2011). Wells 

completed in the adjoining alluvium of the North Canadian 

River (fig. 1) generally are used for livestock but not domestic 

purposes because of poor water quality (Bingham and 

Moore, 1975). 

The terrace deposits in this area are unconsolidated, lensshaped beds of sand, silt, clay, and gravel that were deposited 

by the North Canadian River during previous episodes of 

flooding. These deposits are very permeable and are a major 

source of water in the study area where thick enough to sustain 

acceptable yields (Bingham and Moore, 1975). Wells that 

yield water from only the terrace deposits tend to be shallow 

and produce water with low mineral content (Bingham and 

Moore, 1975). 

The Permian-aged geologic units in the Garber–

Wellington aquifer are the Garber Sandstone and the 

Wellington Formation. The Garber Sandstone consists mostly 

of lenticular beds of orange-brown fine-grained sandstone 

interbedded with siltstone and mudstone and small amounts 

of conglomerate (Breit, 1998). The lithology of the underlying 

Wellington Formation is similar to that of the Garber 

Sandstone but is finer-grained, containing a higher percentage 

of siltstone and mudstone. The stratigraphic contact between 

these two rock units is gradational, and discerning where one 

begins and the other ends is difficult (Smith and others, 2009; 

Parkhurst and others, 1996). Both units were deposited in a 

fluvial-deltaic environment at the edge of a shallow sea that 

periodically covered this part of Oklahoma during the Permian 

Period (Christenson and Havens, 1998). In general, the 

lithologies of the Garber Sandstone and Wellington Formation 
6 Groundwater Quality in Water Samples Collected in Part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, 2011

are highly variable over short distances, horizontally and with 

depth. The bedrock units dip in a westerly direction at about 

50 ft per mile (Christenson and Havens, 1998) and become 

shalier (finer-grained) in an easterly direction and with depth 

(Schlottmann and others, 1998). 

Recent surficial geologic mapping of the area by the 

Oklahoma Geological Survey indicates an absence of terrace 

deposits in the study area compared to maps prepared by 

Bingham and Moore (1975) (T. Stanley, Oklahoma Geological 

Survey, written commun., 2011). Where the terrace deposits 

are absent, wells in this area are completed in an upper 

permeable zone, possibly a highly weathered layer or regolith, 

of the Wellington Formation that underlies and is adjacent 

to the North Canadian River valley. Additionally, the contact 

between the Garber Sandstone and Wellington Formation 

has been mapped farther west of the study area than in the 

original mapping by Bingham and Moore (1975) (T. Stanley, 

Oklahoma Geological Survey, written commun., 2011), 

which would preclude the assumption that some of the wells 

sampled for this study were producing water from the Garber 

Sandstone. The figures in this report use the original mapping 

by Bingham and Moore (1975), but there is potential for 

different interpretation. 

The terrace deposits and underlying bedrock contain 

unconfined aquifers (water table) that are hydraulically 

connected but may contain discontinuous strata that are 

relatively impermeable and locally impede the flow of 

groundwater from the surface and through the aquifer 

(Christenson and Havens, 1998). Groundwater in the study 

area flows in a southwesterly direction toward the North 

Canadian River (Mashburn and Magers, 2011).

The lack of completion logs for wells sampled for this 

study hindered the ability to identify depths of rock strata that 

are a source of trace elements or radionuclides in groundwater. 

Shallow wells generally produce relatively “young” water; 

however, the opposite is not always true, as deep wells do 

not always exclusively produce “older” water from deeper 

parts of an aquifer. Well casing may be open to multiple 

zones in an aquifer to maximize production from deep wells. 

As a result, water produced from deep wells can exhibit 

chemical characteristics of water from shallow, intermediate, 

and deep zones in the aquifer or mixtures from two or more 

zones. Drilling contractors installing private wells in the 

Garber–Wellington aquifer (and other aquifers) decide how a 

well should be constructed by examination of drill cuttings, 

depth to water, and other onsite information (Driscoll, 1986). 

After determining depths of the most favorable zones for 

producing water, well casing is inserted into the borehole 

with screened openings intersecting these layers. Loose sand 

is then used to fill the void space between the borehole and 

the well casing from the bottom of the hole to about 10–20 

ft below land surface (Oklahoma Water Resources Board, 

2011). Examination of available well completion logs in the 

surrounding area indicates that most wells have screened 

casing through at least two zones and sometimes as many as 

four (Oklahoma Water Resources Board, 2011). Local wells 

tend to have screened casing through a permeable layer near 

the upper portion of the borehole and a permeable layer at the 

bottom (Oklahoma Water Resources Board, 2011). For some 

wells, the upper portion is screened in the terrace deposits, and 

the bottom is screened in a sandstone layer in the underlying 

Wellington Formation (Oklahoma Water Resources Board, 

2011). As a result of these factors, each well completion 

is unique, depending on the sequence of the aquifer rocks, 

distribution of the water-bearing zones, and judgment of the 

well driller. 

Previous Studies in Oklahoma

For Permian- and Pennsylvanian-aged sandstones 

in Oklahoma, Al-Shaieb and others (1977) reported that 

uranium and radioactivity were associated with sandstones 

that had (1) a higher than average feldspar content, (2) oil 

production or seepage, (3) high concentrations of organic 

material, or (4) associations with evaporitic depositional 

environments. Christy and Pope (2009) reported that in Logan 

County the highest uranium concentrations were measured 

in water samples collected from wells greater than 295 ft in 

depth, concluding that the highest uranium concentrations 

were probably caused by deep groundwater interaction with 

uraniferous micas and clays in the Wellington Formation and 

the underlying Chase, Council Grove, and Admire Groups. 

The most comprehensive study of trace elements and 

radioactivity in the Central Oklahoma aquifer was done 

by the USGS National Water Quality Assessment Program 

(NAWQA) from 1987 to 1992 (Christenson and Havens, 

1998). That study examined rock cores, analyzed waterquality samples, and simulated water movement through the 

aquifer to describe the location, nature, and causes of selected 

water-quality problems (Christenson and Havens, 1998). 

With respect to water quality, the NAWQA study focused 

on arsenic, chromium, selenium, and uranium because these 

trace elements were the most likely to exceed public drinkingwater MCLs in the aquifer and to affect water suppliers 

and consumers. These trace elements, which commonly 

form oxyanions (negatively charged molecules containing 

a metal atom and oxygen atoms), tend to be soluble in oxic 

(oxygenated) and alkaline groundwaters. Groundwaters of 

this type are commonly found in the United States west of the 

Mississippi River (Hodge and others, 1998; DeSimone, 2009; 

Ayotte and others, 2011). 
Methods 7

Hematite, a mineral composed of iron and oxygen, coats 

sand grains, giving the Permian-aged sediments in Oklahoma 

a characteristic red color. The NAWQA study showed that 

the hematite coatings, other iron oxides, and clay minerals 

in mudstone are significant sources of oxidized arsenic, 

chromium, selenium, and uranium in the Central Oklahoma 

aquifer (Schlottmann and others, 1998). Concentrations 

of these trace elements in the aquifer rocks increase as 

rock particle sizes decrease, with the highest trace-element 

concentrations being measured in fine-grained sediment (clayrich mudstone) (Schlottmann and others, 1998; Gromadzki, 

2004). Negatively charged oxyanions tend to be strongly 

adsorbed to positively charged rims of hematite, other iron 

oxides, and clay minerals. 

For the oxygenated groundwater of the Central 

Oklahoma aquifer, Parkhurst and others (1996) reported that 

concentrations of arsenic, chromium, selenium, and uranium 

are controlled by several factors, including concentrations 

of those elements in the aquifer rocks, water pH, water 

movement, and for uranium, the alkalinity of the water. 

The pH of the water in the Garber–Wellington aquifer at 

depth is controlled by the geochemical process of cation 

exchange. Cation exchange occurs primarily between sodium 

ions in fine-grained clay/mudstone layers and calcium and 

magnesium ions in groundwater that originate from the 

dissolution of dolomite in conglomerates in this aquifer. In 

the deeper parts of the aquifer, where the water is older, the 

exchange of sodium for calcium and magnesium in aquifer 

materials increases dissolution of dolomite in water, which 

increases pH, and, in sequence causes oxyanions of arsenic, 

chromium, selenium, and uranium to desorb from mineral 

surfaces (if present) and become mobile in water (Parkhurst 

and others, 1996, p. C64). Arsenic becomes mobile in 

groundwater at a pH of about 8.5 in the Garber–Wellington 

aquifer (Smith and Christenson, 2005; Becker and others, 

2010); high chromium concentrations (50–100 μg/L) were 

measured at pH values equal to 8.3 or above, and selenium 

and uranium were measured at higher concentrations at 

pH values above 8.0 (Schlottmann and others, 1998). In 

addition to having high pH, groundwater that has undergone 

cation exchange characteristically is enriched with sodium. 

Calcium, magnesium, and bicarbonate are the dominant ions 

in groundwater at depths less than 90 ft (Christenson and 

Havens, 1998, fig. 13), but where the cation exchange process 

is occurring, generally in deeper parts of the aquifer, sodiumbicarbonate water type is predominant. 

Methods

The initial phase of the study was designed to provide a 

reconnaissance assessment of groundwater pH and specific 

conductance in the study area. Values of pH and specific 

conductance were measured for water in the field from 

59 private wells throughout the study area (fig. 3). Wells 

in the study area were selected on the basis of well access, 

knowledge of well depth, and the ability to access untreated 

water near the wellhead. Twenty of the 59 wells were 

subsequently selected and sampled (fig. 3) in summer and fall 

2011. An effort was made to sample wells over a range of well 

depths and pH values and to sample wells that yielded water 

solely from each aquifer and from both aquifers concurrently; 

however, the lack of well-completion logs in the area hindered 

selecting wells on the basis of aquifer information. 

Groundwater samples were analyzed for filtered 

concentrations of major ions, trace elements (including 

arsenic, chromium, and selenium), uranium, radium-226 and 

radium-228, and gross alpha- and gross beta-particle activities 

(table 1, apps. 1, 2, and 3). The concentration of radon-222 gas 

was analyzed in unfiltered water. In addition to alkalinity, the 

water properties temperature, dissolved oxygen concentration, 

pH, and specific conductance were measured in the field. 

Well w28 was sampled by the USGS in December 2008 for 

major ions and trace elements including uranium but was not 

sampled for other radionuclides. This well was destroyed prior 

to this study but is shown on figure 3 and the water-quality 

data are provided in appendixes 1, 2, and 3.

Uranium is a trace element that occurs naturally in 

soils, rocks, and water at trace concentrations but also is a 

radionuclide because all uranium isotopes undergo radioactive 

decay. In this report, uranium is grouped and described 

as a radionuclide and is reported in micrograms per liter. 

Concentrations of the other radionuclides analyzed for this 

study—radium-226, radium-228, and radon-222 gas—and 

gross alpha- and gross beta-particle activities are reported 

in picocuries per liter (table 1), with 1 pCi representing 

2.2 radioactive disintegrations per minute. 

Water-quality data were analyzed by determining water 

type from the predominant ions and making graphs to examine 

relations between constituents and common trends in water 

quality. In regards to water type, cations and anions were 

considered predominant when composing 50 percent or more 

of the total ion concentration expressed in milliequivalents per 

liter. Ions were considered to be secondary when composing 

between 25 and 49 percent of the total cation or anion 

concentration (Back, 1966). 
8 Groundwater Quality in Water Samples Collected in Part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, 2011

! ! !

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w1

w2

w6 w5

w4

w15

w3

w16

w7

w25

w9 w8

w11 w10

w12

w14

w17 w13

w19

w18

w32

w31

w30

w29

w28

w27

w21 w23

w22 w24

w39

w38

w34

w37

w36

w35

w33

w46

w47

w45

w40 w41

w42

w43

w44

w51

w20

w26

w48

w49

w50

w52

w53

w54

w55

w56

w57

w60

w58

w59

1,050

1,083

1,115

1,017

1,148

984

1,050

1,115

1,050

1,050

1,115

1,050

1083

1,083

1,050

1,050

1,148

1,115

1,115

1,115

1,050

1,148

1,017

1,050

1,115

1,050

1083

1,050

1,148

1,115

1050

1,148

1148

1,050

1,115

1148

1,148

1,083

1,050

1,148

1,050

1,148

1,148

1050

1,083

1,050

1,017

1,083

1,017

1,083

1,083

1,148

1,050

1,050

1,083

1115

1,148

1,050

1,115

1,050

1,083

1,017

1148

-97°6' -97°4' -97°2'

35°28'

35°26'

35°24'

Figure 3. Land surface contours, well locations, and pH measurements of water from private wells in part of the Kickapoo Tribe of 

Oklahoma Jurisdictional Area, central Okla., 2011.

Kickapoo Tribe of 

Oklahoma Jurisdictional 

Area boundary

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

Digital elevation model from the U.S. Geological Survey, Earth Resources Observation Systems Data Center, 1999

Albers Equal Area Conic projection, North American Datum 1983

Geology from Lindberg (1987) and Bingham and Moore (1975)

LINCOLN COUNTY

POTTAWATOMIE 

COUNTY

North Canadian River

Study area

EXPLANATION

X

! w22 Well—Water-property measurement 

 only with well identifier (table 2)

Measured pH

Well—Sample collected for chemical

 analysis with well identifier (table 2)

!

w24

Terrace 

deposits

Alluvium Garber Sandstone

Wellington Formation

Chase, Council Grove, and Admire 

Groups (undifferentiated)

Quaternary Permian

5.2–5.9

! 6.0–6.9

! 7.0–7.9

! 8.0–8.7

Land surface contour—Shows altitude of land surface. 

 Contour interval is 33 feet. Datum is North American 

 Vertical Datum of 1988

1,050

! w28 Well—Sampled by the U.S. Geological Survey 

 December 2008. Well was subsequently destroyed

 (table 2)

!

Kickapoo Tribe 

of Oklahoma 

Jurisdictional

Area

0 0.5 1 MILE

0 0.5 1 KILOMETER

Figure 3. Land surface contours, well locations, and pH measurements of water from private wells in part of the Kickapoo Tribe of 

Oklahoma Jurisdictional Area, central Oklahoma, 2011.
Methods 9

Table 1. Maximum Contaminant Levels, method references, and highest minimum laboratory reporting levels of water properties, 

major ions, trace elements, and radionuclides measured in water samples collected from 20 private wells in part of the Kickapoo Tribe 

of Oklahoma Jurisdictional Area, central Oklahoma, 2011.

[All concentrations are of filtered water unless otherwise noted; mg/L, milligrams per liter; —, not applicable; μS/cm, microsiemens per centimeter at 25 degrees 

Celsius; °C, degree Celsius; CaCO3, calcium carbonate; μg/L, micrograms per liter; pCi/L, picocuries per liter]

Water properties and chemical 

constituents (units)

Maximum

Contaminant Level1 

Secondary Maximum 

Contaminant Level1 Method references

Highest

minimum laboratory 

reporting level

Water properties

Dissolved oxygen, field (mg/L) — — Wilde and Radtke (1998) 0.1 

pH, field (standard units) — 6.5–8.5 Wilde and Radtke (1998) 0.1

standard units

Specific conductance,

field (μS/cm at 25oC)

— — Wilde and Radtke (1998) 3 

significant digits

Water temperature, field (oC) — — Wilde and Radtke (1998) 0.5 

Major ions

Calcium (mg/L) — — Fishman (1993) 0.02

Magnesium (mg/L) — — Fishman (1993) 0.012

Potassium (mg/L) — — Fishman and Friedman (1989) 0.06

Sodium (mg/L) — — Fishman (1993) 0.12

Alkalinity, field

(mg/L as CaCO3)

— — Rounds and Wilde (2001) 3

significant digits

Bicarbonate, field (mg/L) — — Rounds and Wilde (2001) 3

significant digits

Carbonate, field (mg/L) — — Rounds and Wilde (2001) 3

significant digits

Chloride (mg/L) — 250 Fishman and Friedman (1989) 0.12 

Fluoride (mg/L) 4 2 Fishman and Friedman (1989) 0.08 

Silica (mg/L) — — Fishman (1993) 0.02 

Sulfate (mg/L) — 250 Fishman and Friedman (1989) 0.18 

Dissolved solids, sum (mg/L) — 500 — 3

significant digits

Trace elements

Antimony (μg/L) 6 — Garbarino and others (2006) 0.027

Arsenic (μg/L) 10 — Garbarino and others (2006) 0.022

Barium (μg/L) 2,000 — Garbarino and others (2006) 0.07

Beryllium (μg/L) 4 — Garbarino and others (2006) 0.006 

Boron (μg/L) — — Garbarino and others (2006);

Garbarino (1999)

3

Bromide (μg/L) — — Fishman and Friedman (1989) 0.02 

Cadmium (μg/L) 5 — Garbarino and others (2006) 0.016 

Chromium (μg/L) 100 — Garbarino and others (2006) 0.06 

Cobalt (μg/L) — — Garbarino and others (2006) 0.02 

Copper (μg/L)2 1,300 1,000 Garbarino and others (2006) 0.05 

Iron (μg/L) — 300 Fishman (1993) 3.2

Lead (μg/L)2 15 — Garbarino and others (2006) 0.015 

Lithium (μg/L) — — Garbarino and others (2006);

Garbarino (1999)

0.22
10 Groundwater Quality in Water Samples Collected in Part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, 2011

Field Methods

Values of pH and specific conductance were measured for 

groundwater from 59 private wells (fig. 3) that ranged in depth 

from 60 to 320 ft. Well depth was determined (if possible) by 

lowering a steel tape in the well casing, by locating the well 

completion log, or from discussion with the well owner. Total 

depths of 10 wells were unknown. All wells had a water spigot 

either on or near the wellhead, enabling access to untreated 

water near the pressure tank. Measurements of pH and specific 

conductance were recorded while the well was pumping after 

Water properties and chemical 

constituents (units)

Maximum

Contaminant Level1 

Secondary Maximum 

Contaminant Level1 Method references

Highest

minimum laboratory 

reporting level

Manganese (μg/L) — 50 Garbarino and others (2006) 0.13 

Molybdenum (μg/L) — — Garbarino and others (2006) 0.014 

Nickel (μg/L) — — Garbarino and others (2006) 0.09 

Selenium (μg/L) 50 — Garbarino and others (2006) 0.03 

Silver (μg/L) — 100 Garbarino and others (2006) 0.005 

Strontium (μg/L) — — Garbarino (1999);

Garbarino and others (2006)

0.2

Thallium (μg/L) 0.5 — Garbarino and others (2006) 0.01

Vanadium (μg/L) — — Garbarino and others (2006) 0.08 

Zinc (μg/L) — 5,000 Garbarino and others (2006) 1.4 

Radionuclides

Uranium, natural (μg/L) 30 — Garbarino and others (2006) 0.004 

Gross alpha particles (pCi/L) 15 — National Environmental 

Methods Index (1980)

3

Gross beta particles (pCi/L) 4 millirems

per year3 

— National Environmental

Methods Index (1980)

4

Radium-226 (pCi/L)

5 (combined)

— U.S. Environmental Protection 

Agency (2008a)

0.1

Radium-228 (pCi/L) — U.S. Environmental Protection 

Agency (1980)

1.0

Radon-222 (pCi/L) not filtered Not finalized4 — American Society

of Testing and Materials 

International (2010)

20

1

U.S. Environmental Protection Agency (2009a).

2

Copper and lead are regulated by a treatment technique that requires systems to control the corrosiveness of the water. If more than 10 percent of tap water 

samples exceed the Maximum Contaminant Level, water systems must take corrective steps. For copper, the action level is 1,300 μg/L, and for lead it is 15 μg/L 

(U.S. Environmental Protection Agency, 2009a).

3

The Maximum Contaminant Level is a concentration of beta particle activity from radionuclides in drinking water that produces an annual radiation dose of 4 

millirems per year (U.S. Environmental Protection Agency, 2000).

4

The Maximum Contaminant Level for radon in public water-supply systems will be 4,000 pCi/L if multimedia mitigation programs are established to address 

radon in indoor air. A second option is a Maximum Contaminant Level of 300 pCi/L for systems that choose not to develop multimedia mitigation programs 

(U.S. Environmental Protection Agency, 2012b).

the measurements had stabilized using a YSI (YSI Inc., Yellow 

Springs, Ohio) multi-probe meter with the sonde immersed in 

a 5-gallon bucket. 

Sampling for each of the 20 wells selected for majorion, trace-element, and radionuclide analysis consisted of 

purging, measuring water properties, collecting water-quality 

samples, and preserving samples. Each well was purged of 

at least three standing well-casing volumes of water before 

sampling. The water properties—specific conductance, pH, 

temperature, and dissolved oxygen—were measured every 5–7 

minutes starting halfway through the purging process by using 

Table 1. Maximum Contaminant Levels, method references, and highest minimum laboratory reporting levels of water properties, 

major ions, trace elements, and radionuclides measured in water samples collected from 20 private wells in part of the Kickapoo Tribe 

of Oklahoma Jurisdictional Area, central Oklahoma, 2011.—Continued

[All concentrations are of filtered water unless otherwise noted; mg/L, milligrams per liter; —, not applicable; μS/cm, microsiemens per centimeter at 25 degrees 

Celsius; °C, degree Celsius; CaCO3, calcium carbonate; μg/L, micrograms per liter; pCi/L, picocuries per liter]
Methods 11

a flow-through chamber with a YSI multiprobe meter (Wilde 

and Radtke, 1998). The meter calibrations were performed 

every morning before use. The pH and specific conductance 

calibrations used standard solutions that bracketed the 

expected values. The highest minimum reporting levels for 

water properties measured in the field are listed in table 1. 

Samples were collected after water properties had stabilized 

following the period of time needed to purge the well. Criteria 

for stabilization were less than a 0.2-unit variation in pH, less 

than a 10-percent variation in specific conductance, and less 

than a 0.3-mg/L variation in dissolved oxygen concentration. 

Some well pumps were operating when the sampling team 

arrived. Those wells were sampled after verifying that the 

volume of water purged was sufficient and that the water 

properties had stabilized. 

Equipment used to sample each well consisted of a 

plastic Y-connector with a polypropylene adaptor (connects 

Y-connector to water spigot), a garden hose, and an adaptor 

for plastic tubing from which samples were collected. Water 

was filtered for dissolved constituents, collected in bottles, 

and preserved in an enclosed portable sampling chamber 

to prevent wind-borne contamination. Water collected for 

analysis of major ions, trace elements, gross alpha- and gross 

beta-particle activities, radium-226, and radium-228 was 

filtered through 0.45-micrometer polysulfone capsule filters 

and collected in acid-rinsed polyethylene bottles that had 

been prerinsed with filtered sample water. All water-quality 

samples were collected and processed by using established 

USGS protocols described in U.S. Geological Survey (2006) 

and Wilde and others (2004). Water-quality samples analyzed 

for trace elements were preserved by acidification with nitric 

acid to a pH of 2 or less. Sample bottles for anion analysis 

were not acid rinsed, nor were those samples acidified. 

Alkalinity, bicarbonate, and carbonate concentrations of 

filtered water were measured in the field or within 4 hours of 

sample collection by using an inflection-point titration method 

described by Rounds and Wilde (2001).

Water samples collected for radon-222 analysis were 

collected as described by U.S. Geological Survey (1987). 

Sample bottles for major ions and trace elements and vials 

for radon-222 were delivered to and analyzed by the USGS 

National Water Quality Laboratory in Lakewood, Colorado. 

Sample vials for radon-222 were shipped overnight for 

delivery within 24 hours. Sample bottles for gross alphaand gross beta-particle activities and radium-226 and 

radium-228 were shipped overnight for delivery within 

24 hours to Eberline Services in Richmond, California. 

Laboratory Analysis

Major anion concentrations were measured by ion 

chromatography (IC) and ion-selective electrode (ISE) 

(Fishman and Friedman, 1989). Major cation concentrations 

were measured by using inductively coupled plasma-atomic 

emission spectrometry (ICP-AES) (Fishman, 1993). Trace 

elements were measured by using collision/reaction cell 

inductively coupled plasma-mass spectrometry (cICP-MS) 

(Garbarino and others, 2006; Garbarino, 1999) and inductively 

coupled plasma-mass spectrometry (ICP-MS) (Fishman, 

1993) (table 1). 

Gross alpha- and gross beta-particle activities were 

measured through gas-flow proportional counting at 72 hours 

after collection and again a second time approximately 30 days 

after the initial count by using a modification of EPA method 

number 900.0 (National Environmental Methods Index, 1980). 

Radium-226 was analyzed by using the radon emanation 

technique (EPA method number 903.1; U.S. Environmental 

Protection Agency, 2008a). Radium-228 was analyzed by 

using coprecipitation and beta counting, a modification of EPA 

method number 904.0 (U.S. Environmental Protection Agency, 

1980). Radon was analyzed by using liquid scintillation 

following the American Society of Testing and Materials 

International standard test method for radon in drinking 

water D5072-09 (American Society of Testing and Materials 

International, 2010). 

Reporting Results of Analysis of Radionuclides

The USGS National Water Quality Laboratory reports 

unrounded values for all radionuclide concentrations and 

activities in picocuries per liter (except for uranium, which is 

reported in micrograms per liter) with the 1-sigma combined 

standard uncertainty (CSU) and sample-specific critical level 

(ssLc) needed to analyze the results (app. 3). The CSU is the 

statistical standard deviation of an individual radionuclide 

concentration and is a function of several variables that can 

cause variances in measurement, one of which is the counting 

error associated with the random nature of radioactive 

decay within any given brief instant of time, which imposes 

limitation on the precision of radioactive counting techniques. 

The CSU is provided with the radionuclide concentration 

and defines upper and lower concentrations for a confidence 

interval of the true concentration (McCurdy and others, 

2008). The ssLc is the lowest concentration measured that 

shows a significant statistical difference from the instrument 

background noise or the analytical blank sample (McCurdy 

and others, 2008). The ssLc is used as the detection level for 

determining if the radionuclide is present in a water sample. 

If the radionuclide concentration is greater than the ssLc, 

the radionuclide is considered to be present in a sample. The 

laboratory also reports a calculated sample-specific minimum 

detectable concentration (MDC) before a sample is analyzed 

to select appropriate analytical methods and parameters for 

the radionuclide measurement (McCurdy and others, 2008). 

In two cases, the ssLc for the sample exceeded the MDC 

because of unexpected chemical or instrument interference. 

These occurrences are noted as “C” in the “Remark” column 

in appendix 3.
12 Groundwater Quality in Water Samples Collected in Part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, 2011

Quality-Assurance Procedures

Decontamination of sampling equipment was performed 

by using USGS standard methods (Wilde, 2004). Qualitycontrol samples consisted of an equipment blank and two 

replicates. The equipment blank was collected to determine 

if samples were contaminated by the sampling equipment 

or bottles. The equipment blank was prepared at the USGS 

Oklahoma Water Science Center laboratory with trace-metalfree blank water and analyzed for major cations, anions, and 

trace elements. The equipment blank was not analyzed for 

radionuclides. The equipment blank analysis (app. 4) indicated 

no contamination from the sampling equipment or bottles for 

the analyzed constituents.

A replicate sample is an extra sample set collected after 

the environmental sample to measure the variability of field 

and laboratory procedures. A replicate was collected from 

wells producing water with a high pH (w33, 8.2) and a low pH 

(w41, 5.5). The analytical accuracy between the environmental 

and replicate samples was computed as the relative percent 

difference (RPD) of constituent concentrations by using the 

following equation: 

 RPD = [(C1 – C2) / ((C1 + C2)/2)] × 100], (1)

where

C1 is the higher of the two concentrations, and 

C2 is the lower of the two concentrations. 

Large RPD values can result from low concentrations 

reported with few significant figures. For example, 

concentrations of 2 and 3 would give an RPD of 40 

percent, whereas if the concentrations were reported with 

more significant figures, such as 2.4 and 2.6, the RPD 

would be 8 percent.

RPD values for the eight major ions (app. 4) ranged 

from 0 to 3.3 percent in the environmental and replicate 

samples from both wells (w33 and w41), except for fluoride, 

which was 40 percent in samples from w41. RPD values for 

the 22 trace elements and uranium (app. 4) ranged from 0 to 

40 percent. For trace-element concentrations, RPD values 

were highest for bromide, iron, manganese, selenium, and 

uranium, ranging from 16.2 to 40 percent. 

Replicate information for radionuclides is shown in 

appendix 5. For both sets (w33 and w41) of replicate-sample 

analyses, concentrations of radium-226, radium-228, and 

radon-222 were within the boundaries of the confidence 

interval of the respective CSUs. Results were similar for 

both sets of replicate sample analyses for gross beta- and 

gross alpha-particle activities except for the gross alphaparticle activity determined 72 hours after sample collection 

for w33; those results were outside the boundaries of the 

confidence interval of the respective CSUs by 0.1 pCi/L, a 

relatively minor amount compared to the measured magnitude 

of the gross alpha-particle activity. There was notable 

background (laboratory blank) activity for w33 (app. 5). Mean 

RPDs for both replicate sets were 12.5 percent for radium-226 

and was slightly higher for gross alpha-particle activity 

(about 19.5 percent for the three samples with detectable 

results). The magnitude of RPD for the concentrations of both 

replicate samples was lower than the relative magnitude of 

the associated CSUs. Measurements were repeatable within 

the bounds imposed by the moderate analytical precision 

obtainable for radioactive counting techniques.

Groundwater Quality

The chemical characteristics of groundwater in the 

Garber–Wellington aquifer change with time and with depth; 

older water generally is found in deeper parts of the aquifer 

(Parkhurst and others, 1996). Minerals in rocks dissolve 

and react with water along groundwater flow paths through 

an aquifer in a process referred to as chemical evolution 

(Plummer and Back, 1980; Hem, 1985). With residence 

time in an aquifer, the chemical quality of water generally 

changes by increases in dissolved solids, with constituent 

concentrations being a product of the chemical composition 

of the aquifer rocks, groundwater, and biogeochemical 

processes in the aquifer (Plummer and Back, 1980; Ayotte 

and others, 2011).

In the Garber–Wellington aquifer, in addition to 

an increase in dissolved solids, chemical evolution of 

groundwater is indicated by a change in water type and an 

increase of pH resulting from cation-exchange processes in 

the aquifer (Schlottmann and others, 1998). The resulting 

increase in pH mobilizes oxyanions of arsenic, chromium, 

selenium, uranium, and other trace elements in groundwater 

(Schlottmann and others, 1998). Studies of other aquifers 

across the United States indicate that groundwater having high 

pH and oxidizing conditions commonly is associated with 

elevated concentrations of trace elements (Ayotte and others, 

2007), especially oxyanions, including arsenic (Robertson, 

1989; Welch and others, 2000) and uranium (Ayotte and 

others, 2011; Jurgens and others, 2009). 

pH Values

Field measurements of groundwater pH from the 59 wells 

measured during the initial reconnaissance ranged from an 

acidic 5.2 to an alkaline 8.7, with a median value of 6.9 (figs. 3 

and 4, tables 2 and 3). The Secondary Maximum Contaminant 

Level (SMCL) for pH in drinking water ranges from 6.5 

to 8.5 for effects not related to health (U.S. Environmental 

Protection Agency, 2012c). Twenty-three wells (39 percent) 

had pH values below 6.5, and two wells (3 percent) had pH 

values above 8.5 (fig. 4). Seventy historical pH measurements 

in the Kickapoo Tribe of Oklahoma Jurisdictional Area ranged 

from 6.3 to 8.9 with a median and average pH of 7.5 (fig. 5A 
Groundwater Quality 13

Table 2. Field measurements, well information, and water type of water collected from private wells in part of the Kickapoo Tribe of 

Oklahoma Jurisdictional Area, central Oklahoma, 2011.

[ID, identifier; USGS, U.S. Geological Survey; μS/cm, microsiemens per centimeter at 25 degrees Celsius; —, not available. Vertical datum is North American 

Vertical Datum of 1988; blue shading indicates samples of mixed cation water types; red shading indicates samples of sodium-bicarbonate water type]

Well and 

sample ID USGS station ID pH

Specific

conductance 

(μS/cm)

Land surface

altitude (feet 

above vertical 

datum)

Well depth (feet 

below land 

surface)

Water type Sampled for 

analysis

w1 352839097053401 7.4 443 1,099 160 No.

w2 352844097034401 5.9 132 1,126 120 Mixed cation Yes.

w3 352812097052101 7.4 346 1,070 143 Mixed cation Yes.

w4 352805097041301 6 230 1,127 95 — No.

w5 352813097033401 5.6 639 1,133 60 — No.

w6 352813097032401 5.7 277 1,112 61 Mixed cation Yes.

w7 352800097032201 6.5 252 1,107 120 — No.

w8 352748097032601 7.5 316 1,112 — — No.

w9 352751097034501 5.2 247 1,115 100 — No.

w10 352756097035501 5.2 125 1,135 125 — No.

w11 352753097040301 5.3 213 1,161 110 — No.

w12 352751097041401 6.2 152 1,132 132 — No.

w13 352745097041501 6.2 224 1,131 — — No.

w14 352743097044101 6 218 1,085 110 — No.

w15 352751097045401 8.2 1,020 1,102 255 — No.

w16 352751097050801 7.2 366 1,100 103 — No.

w17 352747097051401 6.6 285 1,100 180 Mixed cation Yes.

w18 352717097043801 8.3 522 1,077 140 Sodium-bicarbonate Yes.

w19 352733097042101 7.5 327 1,107 110 No.

w20 352732097041501 5.9 184 1,100 102 Mixed cation Yes.

w21 352726097041401 6 223 1,084 — — No.

w22 352728097035001 5.6 143 1,109 110 — No.

w23 352726097035001 5.7 153 1,101 — — No.

w24 352726097031601 6.5 373 1,092 125 Mixed cation Yes.

w25 352734097020001 6.6 275 1,106 222 — No.

w26 352712097032101 6.2 306 1,076 125 — No.

w27 352714097034101 8.5 690 1,087 135 Sodium-bicarbonate Yes.

w281 352710097034601 8.2 443 1,072 220 Sodium-bicarbonate Yes.

w29 352657097042401 6.8 563 1,051 80 — No.

w30 352655097043201 8.7 870 1,052 82 Sodium-bicarbonate Yes.

w31 352652097050501 6.9 810 1,060 120 — No.

w32 352657097054401 7.5 506 1,061 80 — No.

w33 352642097034801 8.2 632 1,150 108 Sodium-bicarbonate Yes.

w34 352704097031401 6.2 261 1,110 150 — No.

w35 352701097031901 6 424 1,090 — — No.

w36 352700097032201 7.4 500 1,076 — — No.

w37 352656097031601 8.4 687 1,082 320 Sodium-bicarbonate Yes.

w38 352651097023201 5.6 181 1,090 120 — No.

w39 352654097022301 8 443 1,101 160 Sodium-bicarbonate Yes.

w40 352635097025201 5.7 251 1,082 150 — No.
14 Groundwater Quality in Water Samples Collected in Part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, 2011

Well and 

sample ID USGS station ID pH

Specific

conductance 

(μS/cm)

Land surface

altitude (feet 

above vertical 

datum)

Well depth (feet 

below land 

surface)

Water type Sampled for 

analysis

w41 352632097024401 5.5 156 1,091 155 Mixed cation Yes.

w42 352625097022401 5.6 146 1,138 172 Mixed cation Yes.

w43 352622097020701 5.4 239 1,119 — — No.

w44 352612097020701 7.8 792 1,085 114 — No.

w45 352620097024201 7.6 513 1,095 150 — No.

w46 352617097031801 7.7 504 1,053 180 — No.

w47 352609097033801 8 559 1,057 180 Sodium-bicarbonate Yes.

w48 352603097024901 8.4 673 1,051 163 Sodium-bicarbonate Yes.

w49 352603097022901 5.7 336 1,085 125 — No.

w50 352557097024101 8.5 809 1,052 180 Sodium-bicarbonate Yes.

w51 352553097021101 8.4 783 1,081 167 Sodium-bicarbonate Yes.

w52 352543097021601 8.1 809 1,092 160 — No.

w53 352536097021101 7.8 709 1,052 — — No.

w54 352533097015901 7.7 626 1,084 240 — No.

w55 352529097021801 8.6 733 1,042 103 — No.

w56 352510097011201 7.3 693 1,103 142 Sodium-bicarbonate Yes.

w57 352458097020801 6.9 744 1,041 — — No.

w58 352417097015301 8.3 415 1,043 110 Sodium-bicarbonate Yes.

w59 352415097013901 7.9 407 1,042 — — No.

w60 352422097012101 7.8 402 1,055 90 — No.

1

Well was sampled and water properties measured by the USGS in December 2008. This well was subsequently destroyed.

Table 2. Field measurements, well information, and water type of water collected from private wells in part of the Kickapoo Tribe of 

Oklahoma Jurisdictional Area, central Oklahoma, 2011.—Continued

[ID, identifier; USGS, U.S. Geological Survey; μS/cm, microsiemens per centimeter at 25 degrees Celsius; —, not available. Vertical datum is North American 

Vertical Datum of 1988; blue shading indicates samples of mixed cation water types; red shading indicates samples of sodium-bicarbonate water type]

and table 3). The range of pH values measured for this study 

was substantially lower than historical pH values; groundwater 

from 23 wells sampled for this study had pH values below the 

historical low pH of 6.3. Acidic groundwater can be a problem 

for well owners because it can corrode metal plumbing and 

fixtures (National Environmental Education Foundation, 

2011). To reduce the intake of shallow acidic water into wells, 

well drillers may extend and cement the outside well casing 

to a depth greater than the minimum required (Oklahoma 

Water Resources Board, 2011). For example, well w15, which 

produced water having a pH of 8.2, was constructed (as 

reported by the well owner) to exclude water from the terrace 

deposits by cementing the upper 40 ft of the borehole. The 

depths of zones with screened casing were unknown, but this 

well was probably completed in the Wellington Formation. 

The driller’s log for well w17 shows it was also probably 

completed in the Wellington Formation and constructed to 

exclude shallow water by cementing the upper 80 ft of the 

borehole (Oklahoma Water Resources Board, 2011). This well 

was screened at 120–130 ft and 165–180 ft and yielded water 

with a pH of 6.6.

Field measurements of specific conductance, used as 

a surrogate for dissolved solids, ranged from 125 to 1,020 

microsiemens per centimeter (μS/cm) with a median of 402 μS/

cm in water from the 59 wells (table 3). Field measurements 

of pH and specific conductance show that values of both 

water properties tended to decrease in wells located at higher 

altitudes. Wells located at higher altitudes, on the terrace 

deposits and above the North Canadian River Valley, tended 

to produce water having lower pH and specific conductance 

values than wells at lower altitudes (figs. 6A and 6B, table 2). 

Wells at higher altitudes tend to be shallower and probably 

yield a greater contribution of water from the terrace deposits 

or shallow permeable zones in the Wellington Formation. 

An exception is well w30, which is relatively shallow, 82 ft, 

and has anomalously high pH (8.7) and specific conductance 

(870 μS/cm) values (fig. 3 and table 2). This well had been 

placed adjacent to (less than 10 ft from) a deeper well (300 

ft deep) that had been previously rendered unusable. The 

high pH and specific conductance values probably reflect the 

contribution of deeper water from the adjacent borehole.
Table 3. Statistical summaries of pH, specific conductance, and concentrations of selected trace elements and radionuclides in water samples collfor this study (2011) and in historical analyses in the Kickapoo Tribe of Oklahoma Jurisdictional Area, central Oklahoma.[MCL, Maximum Contaminant Level; SMCL, Secondary Maximum Contaminant Level; mg/L, milligrams per liter; μg/L, micrograms per liter; pCi/L, picocuries per liter; μS/cft, foot; na, not applicable; —, not calculated because of censored values; ND, not detected]

Constituent Number of wells SMCL–MCL1 Number of wells exceeding SMCL–MCL1 Minimum Percentiles 

25 50 median 75

Historical samples (1954–2008)2, 3

pH 70 6.5–8.5 2 6.3 7.0 7.5 7.9 Specific conductance (μS/cm) 72 na na 100 558 755 945 Well depth (ft) 72 na na 20 57 100 140 Arsenic (μg/L) 46 10 2 0.25 0.25 0.37 1 Uranium (μg/L) 43 30 6 0.01 0.2 1.8 15 Gross alpha-particle activity (pCi/L) 8 15 3 1.4 2.1 2.8 31 Radon-222 10 4300–4,000 2/1 <80 135 210 292 

Sampled wells

pH 20 6.5–8.5 6 5.5 6.3 8 8.4 Specific conductance (μS/cm) 20 na na 132 283 482 688 Dissolved oxygen (mg/L) 19 na na 0.8 3 3.9 5.9 Total dissolved solids (mg/L) 20 500 8 81 160 283 400 Arsenic (μg/L) 20 10 1 0.07 0.20 0.59 1.4 Chromium (μg/L) 20 100 0 <0.06 — 1.2 — Selenium (μg/L) 20 50 1 <0.03 — 0.93 — Uranium (μg/L) 20 30 5 0.02 0.20 1.54 33 Gross alpha-particle activity (72 

hours) (pCi/L)

20 15 8 ND 1.9 5.3 54 

Gross alpha-particle activity (30 days) 

(pCi/L)

20 15 8 ND 0.6 7.3 51 

Gross beta-particle activity (72 hours) 

(pCi/L)

20 50 0 ND 0.6 1.3 2 

Gross beta-particle activity (30 days) 

(pCi/L)

20 50 0 0.8 1.5 2.1 9.6 

Radium (226 and 228 combined) 

(pCi/L)

20 5 0 0.03 0.12 0.45 0.70 

Radon-222 (pCi/L) 20 4300–4,000 8/0 95 168 261 467 
Constituent Number of wells SMCL–MCL1 Number of wells exceeding SMCL–MCL1 Minimum Percentiles 

25 50 median 75 Field measurements pH 59 6.5–8.5 25 5.2 6.0 6.9 7.9 

Specific conductance (μS/cm) 59 na na 125 243 402 636 

Samples having sodium-bicarbonate water type pH 12 6.5–8.5 1 7.3 8.1 8.4 8.4 

Specific conductance (μS/cm) 12 na na 415 550 680 715 Dissolved oxygen (mg/L) 11 na na 0.8 1.6 3.2 3.7 Total dissolved solids (mg/L) 12 500 1 248 326 394 423 Arsenic (μg/L) 12 10 1 0.15 0.56 0.82 5.25 Chromium (μg/L) 12 100 0 <0.06 — 4.6 — Selenium (μg/L) 12 50 1 <0.03 — 8.6 — Uranium (μg/L) 12 30 5 1.1 3.9 27 61 Gross alpha-particle activity (72 hours) (pCi/L) 12 15 8 5 10 42 97 Gross alpha-particle activity (30 days) (pCi/L) 12 15 8 4 11 41 89 Gross beta-particle activity (72 hours) (pCi/L) 12 50 0 ND 0.98 1.8 2.5 Gross beta-particle activity (30 days) (pCi/L) 12 50 0 1.8 3.2 8.1 18 Radium (226 and 228 combined) (pCi/L) 12 5 0 0.03 0.27 0.49 0.85 Radon-222 (pCi/L) 12 4300–4,000 8/0 143 242 395 1,085 

Samples having mixed cation water type pH 8 6.5–8.5 5 5.5 5.7 5.9 6.5 

Specific conductance (μS/cm) 8 na na 132 153 230 300 Dissolved oxygen (mg/L) 8 na na 2.9 5.9 5.9 6.5 Total dissolved solids (mg/L) 8 500 0 81 90 134 169 Arsenic (μg/L) 8 10 0 0.07 0.14 0.19 0.33 Chromium (μg/L) 8 100 0 0.12 0.45 0.75 1.0 

Table 3. Statistical summaries of pH, specific conductance, and concentrations of selected trace elements and radionuclides in water samples collfor this study (2011) and in historical analyses in the Kickapoo Tribe of Oklahoma Jurisdictional Area, central Oklahoma.—Continued[MCL, Maximum Contaminant Level; SMCL, Secondary Maximum Contaminant Level; mg/L, milligrams per liter; μg/L, micrograms per liter; pCi/L, picocuries per liter; μS/cft, foot; na, not applicable; —, not calculated because of censored values; ND, not detected]
Constituent Number of wells SMCL–MCL1 Number of wells exceeding SMCL–MCL1 Minimum Percentiles 

25 50 median 75

Samples having mixed cation water type—Continued

Selenium (μg/L) 8 50 0 0.15 0.21 0.26 0.54 Uranium (μg/L) 8 30 0 0.02 0.07 0.14 0.22 Gross alpha-particle activity (72 hours) 

(pCi/L)

8 15 0 ND 0.87 1.2 2.5 

Gross alpha-particle activity (30 days) 

(pCi/L)

8 15 0 ND ND ND 0.82 

Gross beta-particle activity (72 hours) 

(pCi/L)

8 50 0 ND 0.6 1.2 1.4 

Gross beta-particle activity (30 days) 

(pCi/L)

8 50 0 0.8 0.9 1.2 1.7 

Radium (226 and 228 combined) 

(pCi/L)

8 5 0 0.04 0.12 0.29 0.52 

Radon-222 (pCi/L) 8 4300–4,000 0/0 95 141 168 256 

1U.S. Environmental Protection Agency, 2009a.2Includes well w28 sampled in December 2008 by the U.S. Geological Survey. This well was subsequently destroyed.3Historical water-quality data were retrieved from the U.S. Geological Survey National Water Information System database on December 1, 2011 (U.S. Geological Survey, 204The Maximum Contaminant Level for radon in public water-supply systems will be 4,000 pCi/L if multimedia mitigation programs are established to address radon in indoo

mum Contaminant Level of 300 pCi/L for systems that choose not to develop multimedia mitigation programs (U.S. Environmental Protection Agency, 2012b).

Table 3. Statistical summaries of pH, specific conductance, and concentrations of selected trace elements and radionuclides in water samples collfor this study (2011) and in historical analyses in the Kickapoo Tribe of Oklahoma Jurisdictional Area, central Oklahoma.—Continued[MCL, Maximum Contaminant Level; SMCL, Secondary Maximum Contaminant Level; mg/L, milligrams per liter; μg/L, micrograms per liter; pCi/L, picocuries per liter; μS/cft, foot; na, not applicable; —, not calculated because of censored values; ND, not detected]
The Secondary Maximum Contaminant Level for pH is 6.5 to 8.5 (U.S. Environmental Protection Agency, 2009a) 01234 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 6 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 7 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9 8 8.1 

Number of wells pH, in standard units pH of precipitation in the area was about 5.4 in 2010 (National Atmospheric Deposition Program, 2012) Figure 4. Number of wells and pH values measured in water collected from 59 private wells in part of the Kickapoo Tribe o

Jurisdictional Area, central Okla., 2011. Figure 4. Number of wells and pH values measured in water collected from 59 private wells in part of the Kickapoo Tribe of Oklahoma Juris

central Oklahoma, 2011.
Groundwater Quality 19

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7.1

7.2

7.1

8.2

8.2 8.2

8.2

8.2

8.1

7.9

7.7

7.7

7.6

7.5

7.8

7.2 7.2

6.9

7.7

6.8

7.7

6.6

7.8

8.4

6.7 6.9

8.4

7.4

7.5

6.9

6.6

6.3

7.5

7.1

7.1

7.5

6.5

6.6

7.8

7.5

7.2

8.3

7.4

7.1 7.3

7.6

7.8

7.2

7.4

7.9

6.5

7.5

8.2

8.9

7.1

7.3

7.2

6.7

-97°10' -97°

35°40'

35°30'

35°20'

Historical pH values in groundwater.

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<0.2

2.6

0.5

1.2

7.9 0.3

<0.2 1.1

1.3

1.8

0.4

5.1 0.4 0.9

0.7

<0.2

2.4

<0.2

8.7

0.4

13.7

14.1

16.8

10.1

15.8

10.1

17.7

19.9

<0.02

<0.02

<0.02

<0.02

<0.019

<0.02

-97°10' -97°

35°40'

35°30'

35°20'

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<1

<2

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<1

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<2

<1

1

1

2

1.2

<0.5

<0.5

0.5

<0.5

<0.5

<0.5

<0.5

0.8

0.7

<0.5 <0.5

<0.5

<0.5

 <0.5

0.6 <0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5

<0.5 <0.5

0.9

1.3

9.8

<0.5

3.6

2.3

-97°10' -97°

35°40'

35°30'

35°20'

Historical analyses of arsenic in groundwater.

Concentrations are in micrograms per liter.

pH of sample indicated by color.

Figures 5. Historical water-quality data from wells in the Kickapoo Tribe of Oklahoma Jurisdictional Area, central Oklahoma (A) 

historical pH values in groundwater, (1954 to 2008), (B) historical pH and analyses of arsenic in groundwater (concentrations in 

micrograms per liter), (1977 to 2008), C) historical pH and analyses of uranium in groundwater (concentrations in 

micrograms per liter), (1977 to 2008).

EXPLANATION

A B

C

Historical analyses of uranium in groundwater.

Concentrations are in micrograms per liter.

pH of sample indicated by color.

Albers Equal Area Conic projection, 

North American Datum 1983,

Geology from Lindberg (1987) and Bingham and Moore (1975)

0 5 10 MILES

0 5 10 KILOMETERS

Terrace deposits

Alluvium

Garber Sandstone

Wellington Formation

Chase, Council Grove, and Admire 

Groups (undifferentiated)

Permian

Quaternary

Kickapoo Tribe of Oklahoma 

 Jurisdictional Area boundary

pH

6.0–6.9

7.0–7.9

8.0 and above

Historical sample with constituent

 concentration and color indicating

 pH—Retrieved from the U.S. Geological 

 Survey National Water Information 

 System database December 1, 2011

 (U.S. Geological Survey, 2012)

!

!

!

16.8

!

North 

Canadian 

River

North 

Canadian 

River

North 

Canadian 

River

Figure 5. Historical water-quality data from wells in the Kickapoo Tribe of Oklahoma Jurisdictional Area, central Oklahoma.

A, Historical pH values in groundwater (1954–2008). B, Historical pH and analyses of arsenic in groundwater (concentrations in micrograms 

per liter) (1977–2008). C, Historical pH and analyses of uranium in groundwater (concentrations in micrograms per liter) (1977–2008).
20 Groundwater Quality in Water Samples Collected in Part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, 2011

 The primary source of recharge to the terrace deposits (and 

Garber–Wellington aquifer) is precipitation (Parkhurst and 

others, 1996), which has a relatively low pH and low mineral 

content. The average pH of precipitation in this area of the 

State in 2010 was 5.4 (National Atmospheric Deposition 

Program, 2012). 

Major Ions and Water Types

Groundwater samples from the 20 wells sampled for 

chemical analyses for the study varied from a sodiumbicarbonate water type, characteristic of older water having 

high pH values, to water having multiple ions characteristic 

of younger water having lower pH values. As shown on 

the Piper diagram (Piper, 1944) in figure 7, sodium and 

bicarbonate were the dominant ions in samples from 12 

of the 20 wells (table 2 and fig. 7). These 12 samples had 

high pH values ranging from 7.3 to 8.7 with a median pH 

of 8.4 and concentrations of dissolved solids ranging from 

248 to 501 mg/L with a median value of 394 mg/L (specific 

conductance ranged from 415 to 870 μS/cm with median of 

680 μS/cm) (table 3). One sample, w30, was the only sample 

of 20 collected that exceeded the SMCL for dissolved solids, 

having a concentration of 501 mg/L (app. 1). Both pH and 

specific conductance of the water from these 12 wells were 

higher than for water from the other 8 wells, which were 

characterized as a mixed cation water type (table 3). Those 12 

wells were located mostly in the river valley at lower altitudes 

and probably yield water from deeper zones of the Garber–

Wellington aquifer. The high pH and sodium-bicarbonate 

water type of these samples are indications of the cationexchange process occurring in the aquifer.

Samples from 5 of the 20 wells (w2, w3, w17, w20, and 

w24) were a mixed cation-bicarbonate water type having a 

mixture of calcium, sodium, and magnesium cations in various 

ratios and bicarbonate as the dominant anion (table 2 and fig. 

7). Samples from 3 of the 20 wells, w6, w41, and w42, also 

were a mixed cation water type having a mixture of calcium, 

sodium, and magnesium cations in different ratios but with 

chloride dominant or a mixture of chloride, bicarbonate, and 

sulfate anions (table 2 and fig. 7). These three samples had the 

lowest dissolved solids concentrations (157, 89, and 81 mg/L) 

and the lowest pH values (5.7, 5.5, and 5.6) and show the 

least evidence of cation exchange. Water from these wells is 

probably relatively young water, as indicated by the low pH 

values and dissolved solids concentrations. Values of pH of 

the eight samples having mixed cation water types ranged 

from 5.5 to 7.4, with a median of 5.9, and dissolved solids 

concentrations ranging from 81 to 198 mg/L, with a median 

134 mg/L (table 3). 

Figure 6. Relation of land surface altitude to measurements of A, pH and B, specific conductance of water collected from 59 private wells in

part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, central Okla., 2011.

A w30 B w30

1,020

1,040

1,060

1,080

1,100

1,120

1,140

1,160

1,180

100 300 500 700 900 1,100

Land surface altitude, in feet above sea level

Specific conductance, in microsiemens per centimeter

1,020

1,040

1,060

1,080

1,100

1,120

1,140

1,160

1,180

4 5 6 7 8 9

Land surface altitude, in feet above sea level

pH, in standard units

Well sample—Water-property measurements only

Well sample—Sodium-bicarbonate water type

Well sample—Mixed cation water type

EXPLANATION

Figure 6. Relation of land surface altitude of wells to measurements of A, pH and B, specific conductance of water collected from

59 private wells in part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, central Oklahoma, 2011.
Groundwater Quality 21

Percent of total milliequivalents per liter

Calcium

100

8 0

60

40

20

0

 0 

 20 

 40 

 60 

 80 

 100 

Magnesium

0

20

40

60

80

100

Sodium

plus

potassium

Chloride plus fluoride

0

20

40

60

80

100

100

80

60

40

20

0

Carbonate plus

bicarbonate

Sulfate

20

40

60

80

 100 

Sulfate plus

chloride

0

20

40

60

80

Calcium

plus

magnesium

80

60

40

20

0

80

60

40

20

20

40

60

80

100

A

B

w41 w41

w41 w6

w6 w6 w42

w42

w42

w2

w2

w24 w20

w20

w56

w56

w3 w20

w3

w3

w2

w17

w17

w17 w24

B

Figure 7. Water types and percentages of cations and anions composing water samples collected from 20 private wells in 

part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, central Okla., 2011. 

CATIONS ANIONS

w24

A

sodium 

bicarbonate

calcium 

magnesiumbicarbonate

calcium

magnesiumsulfate chloride

sodiumchloride

w30

0

A Mixed cation water types—

 Younger water least affected

 by cation exchange 

B Sodium-bicarbonate water type—

 Older water altered 

 by cation exchange 

Sampled well with well identifier w51

EXPLANATION

The letter A on the cation triangle of the Piper diagram labels the groups of samples composed of mixed cations. The letter B labels the samples 

of older water classified as sodium-bicarbonate water type. The line connecting the end members, w3 and w30, symbolizes all possible mixtures 

of water represented by the two end members. Water from a well producing from multiple zones in the aquifer will fall somewhere near this line, 

depending on the percentage of contribution from each zone. This line also represents the process of cation exchange and shows the evolution of 

cation replacement of calcium and magnesium by sodium.

100

Figure 7. Water types and percentages of cations and anions composing water samples collected from 20 private wells in part of the 

Kickapoo Tribe of Oklahoma Jurisdictional Area, central Oklahoma, 2011.
22 Groundwater Quality in Water Samples Collected in Part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, 2011

The letter “A” on the cation triangle of the Piper diagram 

labels the groups of samples composed of mixed cations 

(fig. 7). Sample w3 is shown as the least altered sample from 

cation exchange and represents the end member of this group. 

The letter “B” labels the samples of older water classified as 

sodium-bicarbonate water type. Sample w30 is shown to be 

the most altered from cation exchange and represents the end 

member of this water type group. The line connecting the 

end members, w3 and w30, symbolizes all possible mixtures 

of water represented by the two end members. Water from 

a well producing from multiple zones in the aquifer will fall 

somewhere near this line, depending on the percentage of 

contribution from each zone. This line also represents the 

process of cation exchange and shows the evolution of cation 

replacement of calcium and magnesium by sodium. 

Anion concentrations are not directly affected by cation 

exchange and do not plot in distinctive groups on the anion 

triangle similar to the way in which cations do; however, when 

the percentages of anions are plotted with cations on the central 

diamond, samples plot in quadrants of the diamond, revealing 

the general composition of water and the water types (fig. 7). 

Samples dominated by sodium and bicarbonate ions plot in 

the lower quadrant, whereas the two sample groups composed 

of mixed cations plot in two quadrants classified as calcium 

magnesium-bicarbonate and calcium magnesium-sulfate 

chloride water types. 

Trace Elements

Water samples collected from the 20 wells for chemical 

analyses were analyzed for 22 trace elements, of which 10 

have MCLs and 5 have SMCLs (table 1) (U.S. Environmental 

Protection Agency, 2009a). Samples from two wells had 

concentrations exceeding an MCL: the sample from well w39 

had an arsenic concentration of 24.7 μg/L (exceeding the MCL 

of 10 μg/L), and the sample from well w37 had a selenium 

concentration of 147 μg/L (exceeding the MCL of 50 μg/L) 

(figs. 8A and 8C, app. 2). Both of these samples were a sodiumbicarbonate water type and had high pH values, 8.0 and 8.4, 

0.01

0.1

1

10

100

1,000

Selenium, in micrograms per liter

pH, in standard units

Arsenic, in micrograms per liter

pH, in standard units

4 5 6 7 8 9 10

Chromium, in micrograms per liter

pH, in standard units

4 5 6 7 8 9 10

w33 w27 w30

w37 C

0.01

0.1

1

10

100

4 5 6 7 8 9 10

w39 A

0.01

0.1

1

10

100

w33 w27 w30

B

EXPLANATION

Well sample—Sodium-bicarbonate water type

Well sample—Mixed cation water type

Maximum contaminant level for public

 drinking-water supplies (U.S. Environmental

 Protection Agency, 2009a) 

Figure 8. Concentrations of A, arsenic, B, chromium, and 

C, selenium in relation to pH in water samples collected from 

20 private wells in part of the Kickapoo Tribe of Oklahoma 

Jurisdictional Area, central Oklahoma, 2011.
Groundwater Quality 23

respectively. All other trace-element concentrations were below 

MCLs and SMCLs for public drinking-water supplies (app. 2).

A review of historical analyses indicated there were few 

trace-element concentrations in water samples that exceeded 

MCLs. Only 2 of 46 historical analyses for arsenic (16 and 

18 μg/L) exceeded the MCL; the pH of those two samples 

is unknown. There were no historical samples exceeding 

the MCLs for chromium concentration in 42 samples or 

selenium concentration in 30 samples. Because of relatively 

high laboratory reporting levels, most historical traceelement concentrations were censored and were not useful for 

determining relations between trace-element concentrations 

and pH values.

Concentrations of many trace elements in the collected 

water samples show a relation to pH. Arsenic, chromium, 

and selenium concentrations had a positive relation to pH, 

with the highest concentrations occurring in samples having 

pH values above 8.0 (figs. 8A, 8B, and 8C). Three samples, 

however—w27, w30, and w33, with pH values above 8.0—had 

no detectable concentrations of chromium and selenium (figs. 

8B and 8C). This absence of detection may indicate the lack of 

these trace elements in the aquifer matrix along groundwaterflow paths to these wells or that geochemical controls other 

than pH are affecting trace-element mobility in groundwater. 

In water samples collected for this study, other trace 

elements having increasing concentrations with increasing 

pH were boron, molybdenum, and vanadium (fig. 9). In the 

form of oxyanions, these trace elements can compete for 

sorption sites on mineral surfaces and can be released into 

groundwater during the competitive sorption and cationexchange process (Hem, 1985; Robertson, 1989; Ayotte and 

others, 2011). Similar to selenium, vanadium had no detectable 

concentrations in samples from w33, w27, and w30 (fig. 9). 

Concentrations of barium, lithium, and strontium substantially 

decreased at pH values near and above 8.0. Barium and 

strontium are chemically similar to divalent calcium and 

magnesium and may be preferentially removed from the 

groundwater during cation exchange. Lithium is chemically 

similar to monovalent sodium and may be incorporated into 

clay minerals during cation exchange. Beryllium (not shown) 

and nickel had negative relations to pH, with concentrations 

of those trace elements being highest at pH values less than 

6.0 (fig. 9); these constituents tend to undergo hydrolysis but 

in acidic water are commonly present as free cations that are 

sparingly soluble (Ayotte and others, 2011).

Radionuclides

Each radionuclide analyzed for this study has unique 

chemical properties and behaves differently in groundwater 

depending on the geochemical conditions in an aquifer 

(Zapecza and Szabo, 1988). Elevated concentrations of 

uranium and radon in groundwater have been reported to be 

associated with oxygen-rich groundwater having relatively 

high alkalinities and pH values (Zapecza and Szabo, 1988; 

Ayotte and others, 2007; Jurgens and others, 2009) similar to 

conditions in the Garber–Wellington aquifer. Radium-226, a 

decay product of uranium, and radium-228, a decay product 

of thorium, however, are most commonly associated with 

oxygen-depleted (anoxic) groundwater, low pH values, and 

high concentrations of dissolved solids and chlorides (Szabo 

and others, 2012). Radon-222 may be present in elevated 

concentrations under a wide range of chemical conditions in 

groundwater, but concentrations of that isotope are dependent 

in part on the presence of the immediate parent isotope, 

radium-226, in aquifer materials or in groundwater.

Concentrations of uranium, gross alpha-particle activity, 

and radon-222 were highest in the 12 samples having a 

sodium-bicarbonate water type with pH values of 8.0 or more 

(figs. 10A, 10B, and 10C). Uranium concentrations ranged from 

0.02 to 383 μg/L with a median of 1.54 μg/L in the 20 samples 

(table 3), with 5 samples exceeding the MCL of 30 μg/L. 

Samples from these wells (w18, w27, w37, w39, and w51) had 

uranium concentrations ranging from 48.3 to 383 μg/L, with 

pH values ranging from 8.0 to 8.5 (fig. 10A). Samples from 

three wells (w30, w33, and w58), also having high pH and a 

sodium-bicarbonate water type, had uranium concentrations 

less than 2 μg/L and were the only samples of this water type 

that did not exceed the MCL for gross alpha-particle activity 

(fig. 10B). Uranium concentrations in the eight samples having 

mixed cation water types were considerably lower, ranging 

from 0.02 to 0.47 μg/L (fig. 10A). These waters had lower pH 

and bicarbonate concentrations than the sodium-bicarbonate 

water type. Seven of 43 historical analyses (including 

well w28) in the tribal jurisdictional area had uranium 

concentrations exceeding the MCL of 30 μg/L, ranging from 

30.4 to 1,500 μg/L, and had pH values ranging from 7.1 to 8.4 

(figs. 5C and 10A). Both uranium concentrations and gross 

alpha-particle activity had positive relations to pH, with the 

highest concentrations and activities being associated with pH 

values of 8.0 and higher (figs. 10A and 10B). 

In oxidizing groundwater such as that in the Garber–

Wellington aquifer, bicarbonate enhances desorption of 

uranium from mineral surfaces in aquifer rocks (Hsi and 

Langmuir, 1985; Curtis and others, 2004), forming uraniumcarbonate complexes in groundwater (Langmuir, 1978; Hem, 

1985). The effect of this desorption and complexation process 

is evident by the relation between the two constituents, 

with the highest uranium concentrations occurring in 

water samples with bicarbonate concentrations more than 

200 mg/L (fig. 10D). 

Concentrations of radon-222 ranged from 95 to 

3,600 pCi/L in the 20 samples, with a median of 261 pCi/L 

(fig. 10C and table 3). In samples having a sodium-bicarbonate 

water type, radon-222 concentrations ranged from 143 

to 3,600 pCi/L, with a median of 395 pCi/L. Eight of the 

12 samples having this water type, in addition to having pH 

values ranging from 8.0 to 8.7, exceeded the proposed MCL 

for radon-222 of 300 pCi/L (U.S. Environmental Protection 

Agency, 2012b). Because of the short half-life of 3.82 days for 

radon-222, high concentrations of this isotope in a groundwater 

sample indicate that a source of the immediate parent 
110 100 1,000 4 6 8 10 Barium, in micrograms per liter pH, in standard units 110 100 1,000 10,0004 6 8 10 Boron, in micrograms per liter pH, in standard units 110 100 4 6 8 10 Lithium, in micrograms per liter pH, in standard units 0.01 0.1110 4 6 8 10 Molybdenum, in micrograms per liter pH, in standard units 0.01 0.11104 6 8 10 Nickel, in micrograms per liter pH, in standard units 110 100 1,000 4 6 8 10 Strontium, in micrograms per liter pH, in standard units Figure 9. Concentrations of selected trace elements in water samples collected from 20 private wells in part of the Kickapoo Tribe of Okla

Jurisdictional Area, central Okla., 2011. 0.01 0.1110 100 1,0004 

Vanadium, in micrograms per liter pH, 

EXPL

Well sample— water type Well sample—

Figure 9. Concentrations of selected trace elements in water samples collected from 20 private wells in part of the Kickapoo Tribe of Oklahomcentral Oklahoma, 2011.
10

100

1,000

10,000

4 5 6 7 8 9 10

Radon-222,inpicocuriesper liter

pH, in standard units

Figure 10. Concentrations of (A) uranium, (B) gross alpha -particle activity, and (C) radon -222 in relation to pH and (D) uranium in relatio

in water samples collected from 20 private wells for this study (2011) and in historical analyses in the Kickapoo Tribe of Ok lahoma Jurisd

central Okla.

0.01

0.1

1

10

100

1,000

10,000

4 5 6 7 8 9 10

Uranium,inmicrograms per liter

pH, in standard units

A w28

w33

w30

w58

w51

w37

w27

w39 w18

0.1

1

10

100

1,000

4 5 6 7 8 9 10

Grossalphaparticle activity(72hours),

inpicocuriesper liter

pH, in standard units

C

w33 w58 w30

0.01

0.1

1

10

100

1,000

10 100 1,000

Uranium,inmicrogramsper liter

Bicarbonate, in milligrams per liter

BD

EX

Well 

bi

Histo

ReU.NaSyDe

Maxi

LePr

Well 

ca

Propo

Co(UPr

w28

Figure 10. Concentrations of A, uranium, B, gross alpha-particle activity, and C, radon-222 in relation to pH and D, uranium relation to bicarbonate in from 20 private wells for this study (2011) and in historical analyses (1977–2008) in the Kickapoo Tribe of Oklahoma Jurisdictional Area, central Oklaho
26 Groundwater Quality in Water Samples Collected in Part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, 2011

0.01

0.1

1

10

100

1,000

0.1 1 10 100 1,000

Uranium, in micrograms per liter

Gross alpha-particle activity (72 hours),

in picocuries per liter 

Maximum Contaminant Level

 (U.S. Environmental Protection Agency, 2009a)

Well sample—Mixed cation water type

Well sample—Sodium-bicarbonate water type

Historical analyses—Retrieved from the U.S.

 Geological Survey National Water Information 

 System database December 1, 2011 

EXPLANATION

radionuclide radium-226, a product of the uranium-238 decay 

series, is present in aquifer materials near the well. Radon-222 

concentrations in the eight samples having a mixed cation 

water type were lower ranging from 95 to 278 pCi/L, with a 

median of 168 pCi/L. Of 10 historical analyses for radon-222 

in the tribal jurisdictional area, three groundwater samples had 

concentrations exceeding or equaling 300 pCi/L. One sample 

having a radon-222 concentration of 4,900 pCi/L also had 

an elevated uranium concentration of 217 μg/L and a nearly 

neutral pH of 7.2 (fig. 5C). Sodium was the dominant cation of 

this sample, but the lack of a bicarbonate concentration does 

not allow for the determination of water type. 

In the study area, as in the rest of the Garber–Wellington 

aquifer, groundwater is predominately oxygenated (Parkhurst 

and others, 1996), and most pH values were above 6.0 

(75 percent of 20 samples) (table 3 and app. 1), a geochemical 

condition which is not favorable for mobilizing radium from 

aquifer materials (Szabo and others, 2012). Concentrations 

of radium-226 and radium-228 (combined) in the 20 samples 

ranged from 0.03 to 1.7 pCi/L, with a median of 0.45 pCi/L, 

considerably less than the MCL of 5 pCi/L for combined 

radium. No historical samples for radium-226 in the tribal 

jurisdictional area were available, and of two samples 

analyzed for radium-228, each contained a concentration of 

2 pCi/L or lower.

Both uranium-238 and radon-222 are alpha-particle 

emitters during the decay process; however, only uranium 

shows a clearly positive relation to gross alpha-particle 

activity (fig. 11) (radon is not shown, and it is important 

to note that, unlike uranium, radon is lost from samples by 

degassing before the gross alpha-particle activity measurement 

can be made). The relation between uranium concentration 

and gross alpha-particle activity indicates that a predominant 

source of the gross alpha-particle activity is uranium. Gross 

alpha-particle activities in samples with a sodium-bicarbonate 

water type ranged from 5 to 370 pCi/L (median 42 pCi/L) 

at 72 hours and from 4 to 350 pCi/L (median 41 pCi/L) 

at 30 days. Eight of the 12 samples that were a sodiumbicarbonate water type exceeded the 15 pCi/L MCL for gross 

alpha-particle activity in drinking water at 72 hours and at 

30 days (w39, w18, w37, w47, w48, w51, w27, and w50) 

(app. 3 and fig. 11). These samples with a sodium-bicarbonate 

water type had pH values ranging from 8.0 to 8.5. Uranium 

concentrations in five of these samples exceeded the MCL of 

30 μg/L, and the remaining three had uranium concentrations 

exceeding 10 μg/L (fig. 10A). Gross alpha-particle activity 

was substantially lower in samples of mixed cation water 

types with low uranium concentrations. Gross alpha-particle 

activities in mixed cation water type ranged from not detected 

(in one sample) to 5.2 pCi/L (median 1.2 pCi/L) at 72 hours 

and from not detected (in five samples) to 1 pCi/L at 30 days.

Figure 11. Concentrations of uranium related to gross alpha-particle activity at 72 hours after collection in water samples from 

20 private wells for this study (2011) and in historical analyses (1988–1990) in part of the Kickapoo Tribe of Oklahoma Jurisdictional 

Area, central Oklahoma.
Summary 27

Gross beta-particle activity also was higher in samples 

of sodium-bicarbonate water type than in samples of mixed 

cation water types and increased in both water types (15 

of 20 samples) from 72 hours to 30 days. An increase in 

gross beta-particle activity over time probably results from 

ingrowth and decay of uranium daughter products that emit 

beta particles (Welch and others, 1995; Szabo and others, 

2007). In sodium-bicarbonate water type, gross beta-particle 

activities ranged from not detected in three samples to 

8.6 pCi/L at 72 hours (median 1.8 pCi/L) and from 1.8 to 

102 pCi/L (median 8.1 pCi/L) at 30 days (app. 3 and table 3). 

Gross beta-particle activities in mixed cation water types were 

substantially less, ranging from not detected in two samples 

to 1.7 pCi/L at 72 hours and from 0.8 to 1.7 pCi/L at 30 days 

(median 1.2 pCi/L). The absence of an increase in betaparticle activity with time after sample collection is consistent 

with the low concentrations of uranium measured in the mixed 

cation water types.

Relation Between pH and Occurrence 

of Trace Elements and Radionuclides

Water-quality data collected during this study show that 

pH values above 8.0 are useful indicators for potentially high 

concentrations of uranium, radon-222, and gross alpha-particle 

activity in groundwater in the study area. This relation can 

be expected to be valid as long as the waters are also oxic. 

High pH values also are a useful indicator for potentially 

high concentrations of arsenic, chromium, and selenium in 

groundwater when these elements occur in the aquifer matrix 

along groundwater-flow paths. Values of pH were higher in 

wells completed in the Wellington Formation (of the Garber–

Wellington aquifer), and deeper water had a higher potential 

for greater concentrations of uranium and the other oxyanions. 

In general, concentrations of uranium and several other 

trace elements in groundwater in the study area are related 

to pH, oxic conditions, concentrations of the elements in the 

aquifer matrix, and groundwater-flow paths. The aquifer 

geochemistry tends to be strongly oxic, which supports 

these geochemical conditions even at substantial depths. The 

highest concentrations of uranium and other trace elements 

in the study area tended to occur in sodium-bicarbonate 

water type having pH values above 8.0. Concentrations of 

uranium and other trace elements in the aquifer rocks tended 

to increase with depth as the sediments become finer-grained 

in the Garber–Wellington aquifer (Gromadzki, 2004). It is 

likely that groundwater moves more slowly through these 

sediments, and with increased residence time, concentrations 

of dissolved solids (and specific conductance) increase. 

Shallow wells that produce young water of mixed cation 

water types having low pH values and low concentrations 

of dissolved solids appear to be less likely to contain high 

concentrations of radionuclides and trace elements and gross 

alpha- and beta-particle activities. 

Summary

An assessment of groundwater quality was conducted 

by the U.S. Geological Survey during 2011, in cooperation 

with the Kickapoo Tribe of Oklahoma, to describe the 

occurrence of radionuclides and selected trace elements 

in groundwater and to determine if pH could be used 

as a surrogate for laboratory analyses to quickly and 

inexpensively identify wells that may contain relatively high 

concentrations of radionuclides. Residents of this rural area 

use groundwater from Quaternary-aged terrace deposits and 

the Permian-aged Garber–Wellington aquifer for domestic 

purposes. Measurements of pH and specific conductance 

from 59 private wells had a positive relation to land-surface 

altitude; water samples from shallow wells completed in the 

terrace deposits (at higher altitudes) tended to have lower 

pH values and lower dissolved solids concentrations than 

water samples from deeper wells completed in the Wellington 

Formation. Water samples from 20 wells, selected for 

chemical analyses, varied from a sodium-bicarbonate water 

type, characteristic of water with longer residence times in the 

aquifer having high pH values from cation exchange, to mixed 

cation water types, characteristic of more recently recharged 

water having lower pH values. Sodium and bicarbonate were 

the dominant cation and anion in samples from 12 of 20 wells 

sampled. Those 12 samples had high pH values ranging from 

7.3 to 8.7 (median of 8.4) and concentrations of dissolved 

solids ranging from 248 to 501 milligrams per liter (mg/L) 

(median of 394 mg/L). In general, those 12 samples had the 

highest concentrations of selected trace elements and the 

radionuclides uranium and radon-222 and the highest gross 

alpha-particle activity. 

Other trace elements that had a positive relation to pH 

were boron, molybdenum, and vanadium. Concentrations 

of barium, lithium, and strontium increased with pH but 

substantially decreased at pH values near and above 8.0, 

similar to calcium and magnesium. Elements that showed 

a negative relation to pH were nickel and beryllium, with 

concentrations of those trace elements being highest at pH 

values lower than 6.

Uranium concentrations ranged from 0.02 to 

383 micrograms per liter (μg/L) (median of 1.54 μg/L) with 

the samples from 5 of the 20 wells exceeding the Maximum 

Contaminant Level (MCL) for public drinking-water supplies 

of 30 μg/L. The five wells with uranium concentrations 

exceeding 30 μg/L had pH values ranging from 8.0 to 8.5. 

Concentrations of radium-226 and radium-228 (combined) 

ranged from 0.03 to 1.7 picocuries per liter (pCi/L), well 

below the MCL of 5 pCi/L. Radon-222 concentrations ranged 

from 95 to 3,600 pCi/L (median of 261 pCi/L), with eight 

samples exceeding the proposed MCL of 300 pCi/L. Those 

eight samples had a sodium-bicarbonate water type and pH 

values ranging from 8.0 to 8.7. Eight samples exceeded the 

15 pCi/L MCL for gross alpha-particle activity at 72 hours 

after collection and at 30 days after the initial count. Those 

samples were a sodium-bicarbonate water type and had 
28 Groundwater Quality in Water Samples Collected in Part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, 2011

pH values ranging from 8.0 to 8.5. All eight samples had 

uranium concentrations exceeding 10 μg/L and included the 

five samples exceeding the MCL of 30 μg/L indicating that 

uranium is the dominant source of the gross alpha-particle 

activity. Gross beta-particle activity in 15 of the 20 samples 

showed an increase from 72 hours to 30 days. An increase 

in gross beta-particle activity over time probably was caused 

by the ingrowth and decay of uranium daughter products that 

emit beta particles. 

Water-quality data collected for this study indicate that 

pH values above 8.0 are a useful indicator for potentially 

high concentrations of uranium, gross alpha-particle activity, 

and radon-222, in the study area. The waters are oxic and 

contain abundant bicarbonate, both of which promote 

uranium solubility. Values of pH also are a useful indicator 

for potentially high concentrations of arsenic, chromium, and 

selenium in groundwater when these elements occur in the 

aquifer matrix along groundwater-flow paths

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32 Groundwater Quality in Water Samples Collected in Part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, 2011
Appendixes 1–5 33

Appendixes 1–5
Appendix 1. Water-property measurements and concentrations of major ions measured in water samples collected from 20 private wells in part of tOklahoma Jurisdictional Area, central Oklahoma, 2011. [ID, identifier; USGS, U.S. Geological Survey; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; —, not measured or calculated; CaCO3, caSiO2, silicon dioxide; E, estimated, mean titrant volume error indicates that substances in addition to bicarbonate were neutralized during titration; <, less than] Well ID USGS station ID Sample date YYYYMMDD Dissolved oxygen, in mg/L pH, in standard units Specific con- ductance, in μS/cm Dissolved solids, sum, in mg/L Calcium, in mg/L Magnesium, in mg/L P

w2 352844097034401 20110926 2.9 5.9 132 90 9.47 3.54 w3 352812097052101 20110822 6.7 7.4 346 194 33.8 14.2 w6 352813097032401 20110823 5.9 5.7 277 157 15.9 6.24 w17 352747097051401 20110913 5.9 6.6 285 161 19.7 9.11 w18 352717097043801 20111004 3.5 8.3 522 315 11.1 5.3 w20 352732097041501 20111012 6.4 5.9 184 110 15.3 6.43 w24 352726097031601 20111012 8.9 6.5 373 198 28.1 11.8 w27 352714097034101 20110822 0.8 8.5 690 401 2.58 1.39 w281 352710097034601 20081203 1.6 8.2 443 2251 17.4 8.68 w30 352655097043201 20110830 2.2 8.7 870 501 1.94 0.838 w33 352642097034801 20110912 3.2 8.2 632 367 5.34 2.35 w37 352656097031601 20110928 0.8 8.4 687 409 4.42 2.13 w39 352654097022301 20110830 3.9 8 443 251 19.4 10.9 w41 352632097024401 20110831 5.9 5.5 156 89 11.1 4.42 w42 352625097022401 20110926 5.9 5.6 146 81 11.6 4.23 w47 352609097033801 20110830 3.2 8 559 330 8.95 5.61 w48 352603097024901 20110823 — 8.4 673 400 2.84 1.68 w50 352557097024101 20111005 1 8.5 809 485 3.13 1.83 w51 352553097021101 20110906 3.3 8.4 783 464 4.93 2.35 w56 352510097011201 20110831 4.3 7.3 693 389 28.5 14.5 w58 352417097015301 20110823 5.5 8.3 415 248 5.07 2.9 
Well ID USGS station ID Date of sample Alkalinity, in mg/L as CaCO3 Bicarbonate, in mg/L Bromide, in mg/L Carbon dioxide, in mg/L Carbonate, in mg/L Chloride, in mg/L Fluoride, in mg/L 

w2 352844097034401 20110926 38 46 0.09 100 0 7.32 0.14 w3 352812097052101 20110822 170 207 0.05 13 0 6.89 0.16 w6 352813097032401 20110823 21 E26 0.31 93 0 49.1 <0.04 w17 352747097051401 20110913 121 147 0.1 58 0 8.73 0.16 w18 352717097043801 20111004 222 265 0.1 2.1 3 26 0.7 w20 352732097041501 20111012 59 72 0.11 150 0 9.63 0.27 w24 352726097031601 20111012 104 126 0.31 69 0 23.8 0.28 w27 352714097034101 20110822 263 312 0.12 1.6 5 30.9 1 w281 352710097034601 20081203 227 275 0.06 2.9 1 4.67 0.24 w30 352655097043201 20110830 273 315 0.23 1.1 8 76.5 1.23 w33 352642097034801 20110912 238 284 0.12 2.8 3 29.7 0.82 w37 352656097031601 20110928 281 334 0.1 2.2 4 27.1 0.85 w39 352654097022301 20110830 173 209 0.11 3.6 0 16.1 0.36 w41 352632097024401 20110831 22 27 0.13 133 0 15.8 0.04 w42 352625097022401 20110926 22 27 0.09 118 0 11.7 0.04 w47 352609097033801 20110830 258 311 0.05 5.5 2 12.6 0.49 w48 352603097024901 20110823 308 365 0.07 2.1 5 16.1 0.57 w50 352557097024101 20111005 328 388 0.15 2.1 6 41.4 0.72 w51 352553097021101 20110906 291 347 0.11 2 4 28.8 0.89 w56 352510097011201 20110831 252 306 0.23 23 0 40.6 0.47 w58 352417097015301 20110823 173 207 0.07 1.7 2 17.9 0.25 

1Well was sampled and water properties measured by the USGS in December 2008. Well was subsequently destroyed.2Dissolved solids of filtered water dried at 180 degrees Celsius.
Appendix 2. Trace-element concentrations measured in water samples collected from 20 private wells in part of the Kickapoo Tribe of Oklahoma JuOklahoma, 2011. [ID, identifier; USGS, U.S. Geological Survey; μg/L, micrograms per liter; <, less than ; E, estimated, result is below the laboratory reporting level and above the long-term met

Well ID USGS station ID Sample date Antimony, in μg/L Arsenic, in μg/L Barium, in μg/L Beryllium, in μg/L Boron, in μg/L Bromide, in mg/L Cadmium, in μg/L Chromium, in μg/L Cob

in μ

w2 352844097034401 20110926 <0.03 0.15 60 0.04 28 0.09 <0.02 0.52 <w3 352812097052101 20110822 <0.03 0.62 159 <0.01 56 0.05 <0.02 2.7 <w6 352813097032401 20110823 <0.03 0.16 83 0.25 23 0.31 <0.02 0.61 w17 352747097051401 20110913 <0.03 0.63 88 0.01 85 0.1 <0.02 0.9 w18 352717097043801 20111004 0.05 6.6 108 0.01 1,050 0.1 <0.02 3.2 <w20 352732097041501 20111012 <0.03 0.22 75 0.04 37 0.11 <0.02 1.2 <w24 352726097031601 20111012 <0.03 0.23 95 0.02 54 0.31 <0.02 1 w27 352714097034101 20110822 <0.03 6.8 57 0.02 1,630 0.12 <0.02 <0.06 <w281 352710097034601 20081203 E.04 3.6 239 <0.02 647 0.06 <0.02 0.24 Ew30 352655097043201 20110830 <0.03 0.15 45 0.04 2,460 0.23 <0.02 <0.06 w33 352642097034801 20110912 <0.03 0.54 68 0.04 2,050 0.12 <0.02 <0.06 w37 352656097031601 20110928 <0.03 4.8 51 0.02 1,670 0.1 <0.02 4.5 <w39 352654097022301 20110830 0.05 24.7 97 0.01 802 0.11 <0.02 1.3 w41 352632097024401 20110831 <0.03 0.07 61 0.18 29 0.13 <0.02 0.26 w42 352625097022401 20110926 <0.03 0.1 64 0.08 26 0.09 <0.02 0.12 w47 352609097033801 20110830 <0.03 0.33 115 0.01 624 0.05 <0.02 24.4 <w48 352603097024901 20110823 <0.03 0.57 40 0.01 651 0.07 <0.02 31.4 <w50 352557097024101 20111005 <0.03 0.72 43 0.01 979 0.15 <0.02 15.6 <w51 352553097021101 20110906 <0.03 3.1 39 0.02 1,760 0.11 <0.02 4.7 <w56 352510097011201 20110831 <0.03 0.73 130 <0.01 262 0.23 <0.02 11.2 <w58 352417097015301 20110823 <0.03 0.9 110 <0.01 192 0.07 <0.02 8.6 <
Well

ID

USGS

station ID

Sample 

date

Lead,

in μg/L

Lithium,

in μg/L

Manganese,

in μg/L

Molybdenum,

in μg/L

Nickel,

in μg/L 

Selenium, 

in μg/L

Silver,

in μg/L

Strontium, 

in μg/L

Thallium

in μg/L

w2 352844097034401 20110926 0.39 7.1 <0.1 <0.01 1.6 1.1 <0.01 58.5 <0.01 w3 352812097052101 20110822 0.03 14.4 <0.1 0.03 <0.09 0.23 <0.01 115 <0.01 w6 352813097032401 20110823 0.06 13.4 5.3 0.02 5.9 0.15 <0.01 78.9 <0.01 w17 352747097051401 20110913 0.03 16 0.7 0.03 0.29 0.36 <0.01 110 <0.01 w18 352717097043801 20111004 <0.03 9.3 <0.1 1.49 <0.09 0.76 <0.01 98.1 <0.01 w20 352732097041501 20111012 0.03 6.4 0.4 0.03 0.68 0.3 <0.01 95.4 <0.01 w24 352726097031601 20111012 0.06 7.5 <0.1 0.09 0.82 1.2 <0.01 149 <0.01 w27 352714097034101 20110822 0.05 7.5 1.5 2 <0.09 <0.03 0.01 53.1 <0.01 w281 352710097034601 20081203 <0.06 13.6 0.7 0.47 E0.11 5.1 <0.01 262 <0.04 w30 352655097043201 20110830 0.16 7.8 3.1 3.16 <0.09 <0.03 <0.01 36.2 <0.01 w33 352642097034801 20110912 <0.01 6.6 4.3 1.57 <0.09 <0.03 0.01 87.8 <0.01 w37 352656097031601 20110928 <0.01 7.3 <0.1 1.51 <0.09 147 <0.01 64.2 <0.01 w39 352654097022301 20110830 0.07 9.7 <0.1 0.65 0.1 36.8 <0.01 288 <0.01 w41 352632097024401 20110831 0.14 7.4 0.4 <0.01 4.2 0.2 <0.01 82.8 <0.01 w42 352625097022401 20110926 0.06 5.4 0.6 <0.01 3.2 0.22 <0.01 94.3 <0.01 w47 352609097033801 20110830 <0.01 16.5 <0.1 0.55 <0.09 24 <0.01 178 <0.01 w48 352603097024901 20110823 0.18 13.7 <0.1 0.62 <0.09 12.8 <0.01 48 <0.01 w50 352557097024101 20111005 <0.03 9.2 <0.1 1.29 <0.09 29.3 <0.01 50.1 <0.01 w51 352553097021101 20110906 <0.01 10 0.3 1.93 <0.09 23.1 <0.01 80.7 <0.01 w56 352510097011201 20110831 0.03 20.8 <0.1 0.18 <0.09 4.4 <0.01 144 <0.01 w58 352417097015301 20110823 0.03 10.2 <0.1 0.14 <0.09 2.8 <0.01 45.2 <0.01 

1Well was sampled and water properties measured by the USGS in December 2008. Well was subsequently destroyed.
Appendix 3. Radionuclide concentrations measured in water samples collected from 20 private wells in part of the Kickapoo Tribe of Oklahoma Juricentral Oklahoma, 2011. [ID, identifier; USGS, U.S. Geological Survey; Result, radiological concentrations plus or minus the 1-sigma combined standard uncertainty; GA (30d), sample used for the 72-his counted a second time approximately 30 days after the initial count as referenced to a detector calibrated by using 230Thorium; ND, analyte not detected (concentration is less level); pCi/L, picocurie per liter; GA (72h), sample analyzed for gross alpha-particle activity at approximately 72 hours after sample collection as referenced to a detector calibra(30d), sample used for the 72-hour gross beta-particle analysis is counted a second time approximately 30 days after the initial count as referenced to a detector calibrated by usiple analyzed for gross beta-particle activity at approximately 72 hours after sample collection as referenced to a detector calibrated by using 137Cesium; μg/L, micrograms per lhigh range exceeded; B, laboratory background blank greater than the sample-specific critical level; C, sample-specific critical level exceeded the minimum detectable concentracontrol sample recovery is outside acceptable range; ±, plus or minus] Well ID USGS station ID Sample date YYYYMMDD Sample time Radiological constituent Result Sample-specific critical level Remark U

w2 352844097034401 20110926 1430 GA (30d) -0.3 ± 0.26 0.48 ND pCw2 352844097034401 20110926 1430 GA (72h) 1.5 ± 0.51 0.51 pCw2 352844097034401 20110926 1430 GB (30d) 0.9 ± 0.4 0.6 pCw2 352844097034401 20110926 1430 GB (72h) 0.8 ± 0.4 0.61 pCw2 352844097034401 20110926 1430 Radium-226 0.076 ± 0.015 0.018 pCw2 352844097034401 20110926 1430 Radium-228 0.25 ± 0.081 0.19 pCw2 352844097034401 20110926 1430 Radon-222 170 ± 15 13.8 pCw2 352844097034401 20110926 1430 Uranium 0.02 0.004 μw3 352812097052101 20110822 1345 GA (30d) 0.9 ± 0.66 0.85 pCw3 352812097052101 20110822 1345 GA (72h) 4 ± 0.73 0.51 pCw3 352812097052101 20110822 1345 GB (30d) 1.7 ± 0.43 0.61 pCw3 352812097052101 20110822 1345 GB (72h) 1.6 ± 0.31 0.42 pCw3 352812097052101 20110822 1345 Radium-226 0.21 ± 0.027 0.015 pCw3 352812097052101 20110822 1345 Radium-228 0.49 ± 0.094 0.2 pCw3 352812097052101 20110907 1030 Radon-222 117 ± 11 10.7 pCw3 352812097052101 20110822 1345 Uranium 0.23 0.004 μw6 352813097032401 20110823 0915 GA (30d) 0.3 ± 0.42 0.59 ND pCw6 352813097032401 20110823 0915 GA (72h) 0.3 ± 0.31 0.45 ND pCw6 352813097032401 20110823 0915 GB (30d) 1.4 ± 0.43 0.62 pCw6 352813097032401 20110823 0915 GB (72h) 0.3 ± 0.28 0.44 ND pCw6 352813097032401 20110823 0915 Radium-226 0.042 ± 0.012 0.015 pCw6 352813097032401 20110823 0915 Radium-228 -0.01 ± 0.095 0.23 ND pCw6 352813097032401 20110906 1130 Radon-222 251 ± 18 12.1 pCw6 352813097032401 20110823 0915 Uranium 0.03 0.004 μw17 352747097051401 20110913 1100 GA (30d) 0.8 ± 0.5 0.59 pCw17 352747097051401 20110913 1100 GA (72h) 1 ± 0.42 0.53 B pC
Well ID USGS station ID Sample date YYYYMMDD Sample time Radiological constituent Result Sample-specific critical level Remark U

w17 352747097051401 20110913 1100 GB (30d) 1.7 ± 0.44 0.62 pw17 352747097051401 20110913 1100 GB (72h) 1.2 ± 0.29 0.42 pw17 352747097051401 20110913 1100 Radium-226 0.15 ± 0.021 0.018 pw17 352747097051401 20110913 1100 Radium-228 0.4 ± 0.1 0.23 pw17 352747097051401 20110913 1100 Radon-222 167 ± 14 10.9 pw17 352747097051401 20110913 1100 Uranium 0.15 0.004 μw18 352717097043801 20111004 1400 GA (30d) 350 ± 36 0.85 pw18 352717097043801 20111004 1400 GA (72h) 370 ± 38 0.47 pw18 352717097043801 20111004 1400 GB (30d) 102 ± 5.8 0.67 pw18 352717097043801 20111004 1400 GB (72h) 6.9 ± 0.71 0.48 pw18 352717097043801 20111004 1400 Radium-226 0.77 ± 0.069 0.021 pw18 352717097043801 20111004 1400 Radium-228 0.68 ± 0.13 0.26 pw18 352717097043801 20111004 1400 Radon-222 1,680 ± 93 12.2 pw18 352717097043801 20111004 1400 Uranium 383 0.004 D μw20 352732097041501 20111012 1000 GA (30d) 0.2 ± 0.28 0.42 ND pw20 352732097041501 20111012 1000 GA (72h) 0.8 ± 0.43 0.51 pw20 352732097041501 20111012 1000 GB (30d) 0.8 ± 0.3 0.45 pw20 352732097041501 20111012 1000 GB (72h) 0.3 ± 0.39 0.61 ND pw20 352732097041501 20111012 1000 Radium-226 0.07 ± 0.013 0.018 pw20 352732097041501 20111012 1000 Radium-228 0.17 ± 0.09 0.2 ND pw20 352732097041501 20111012 1000 Radon-222 278 ± 19 11.6 pw20 352732097041501 20111012 1000 Uranium 0.21 0.004 μw24 352726097031601 20111012 1330 GA (30d) 1 ± 0.49 0.63 pw24 352726097031601 20111012 1330 GA (72h) 5.2 ± 1.1 0.9 pw24 352726097031601 20111012 1330 GB (30d) 1.7 ± 0.41 0.6 pw24 352726097031601 20111012 1330 GB (72h) 1.7 ± 0.56 0.85 pw24 352726097031601 20111012 1330 Radium-226 0.095 ± 0.014 0.016 pw24 352726097031601 20111012 1330 Radium-228 0.42 ± 0.088 0.19 pw24 352726097031601 20111012 1330 Radon-222 149 ± 13 11.6 pw24 352726097031601 20111012 1330 Uranium 0.47 0.004 μw27 352714097034101 20110822 1030 GA (30d) 116 ± 13 1.4 C pw27 352714097034101 20110822 1030 GA (72h) 114 ± 12 1.1 pw27 352714097034101 20110822 1030 GB (30d) 22 ± 1.7 1 pw27 352714097034101 20110822 1030 GB (72h) 1.6 ± 0.56 0.75 p
Well ID USGS station ID Sample date YYYYMMDD Sample time Radiological constituent Result Sample-specific critical level Remark U

w27 352714097034101 20110822 1030 Radium-226 0.43 ± 0.042 0.016 pw27 352714097034101 20110822 1030 Radium-228 0.29 ± 0.15 0.24 pw27 352714097034101 20110906 1100 Radon-222 3,600 ± 200 12 pw27 352714097034101 20110822 1030 Uranium 77.9 0.004 μw28 352710097034601 20081203 1030 Uranium 1,500 0.006 D μw30 352655097043201 20110830 1430 GA (30d) 4 ± 1.1 1 pw30 352655097043201 20110830 1430 GA (72h) 5.3 ± 1.3 1.2 B pw30 352655097043201 20110830 1430 GB (30d) 1.5 ± 0.61 0.91 pw30 352655097043201 20110830 1430 GB (72h) 0.8 ± 0.65 1 ND pw30 352655097043201 20110830 1430 Radium-226 0.18 ± 0.023 0.017 pw30 352655097043201 20110830 1430 Radium-228 0.33 ± 0.12 0.24 L pw30 352655097043201 20110906 1000 Radon-222 350 ± 23 12 pw30 352655097043201 20110830 1430 Uranium 1.46 0.004 μw33 352642097034801 20110912 1230 GA (30d) 11.1 ± 1.7 0.82 pw33 352642097034801 20110912 1230 GA (72h) 5 ± 1.1 0.93 B pw33 352642097034801 20110912 1230 GB (30d) 3.5 ± 0.54 0.71 pw33 352642097034801 20110912 1230 GB (72h) 2.8 ± 0.52 0.73 pw33 352642097034801 20110912 1230 Radium-226 1.2 ± 0.1 0.016 pw33 352642097034801 20110912 1230 Radium-228 0.53 ± 0.11 0.23 pw33 352642097034801 20110912 1230 Radon-222 1,220 ± 69 11.9 pw33 352642097034801 20110912 1230 Uranium 1.09 0.004 μw37 352656097031601 20110928 1430 GA (30d) 80 ± 8.9 1 pw37 352656097031601 20110928 1430 GA (72h) 77 ± 8.6 1.1 pw37 352656097031601 20110928 1430 GB (30d) 16.4 ± 1.3 1.2 pw37 352656097031601 20110928 1430 GB (72h) 1.9 ± 0.66 0.92 pw37 352656097031601 20110928 1430 Radium-226 -0.01 ± 0.01 0.021 ND p

Appendix 3. Radionuclide concentrations measured in water samples collected from 20 private wells in part of the Kickapoo Tribe of Oklahoma Juricentral Oklahoma, 2011.—Continued [ID, identifier; USGS, U.S. Geological Survey; Result, radiological concentrations plus or minus the 1-sigma combined standard uncertainty; GA (30d), sample used for the 72-is counted a second time approximately 30 days after the initial count as referenced to a detector calibrated by using 230Thorium; ND, analyte not detected (concentration is lescal level); pCi/L, picocurie per liter; GA (72h), sample analyzed for gross alpha-particle activity at approximately 72 hours after sample collection as referenced to a detector calGB (30d), sample used for the 72-hour gross beta-particle analysis is counted a second time approximately 30 days after the initial count as referenced to a detector calibrated by sample analyzed for gross beta-particle activity at approximately 72 hours after sample collection as referenced to a detector calibrated by using 137Cesium; μg/L, micrograms method high range exceeded; B, laboratory background blank greater than the sample-specific critical level; C, sample-specific critical level exceeded the minimum detectable claboratory control sample recovery is outside acceptable range; ±, plus or minus]
Well ID USGS station ID Sample date YYYYMMDD Sample time Radiological constituent Result Sample-specific critical level Remark U

w37 352656097031601 20110928 1430 Radium-228 0.48 ± 0.089 0.2 pCw37 352656097031601 20110928 1430 Radon-222 640 ± 38 11 pCw37 352656097031601 20110928 1430 Uranium 55.1 0.004 μw39 352654097022301 20110830 0900 GA (30d) 260 ± 27 0.66 pCw39 352654097022301 20110830 0900 GA (72h) 270 ± 29 0.71 B pCw39 352654097022301 20110830 0900 GB (30d) 89 ± 5 0.57 pCw39 352654097022301 20110830 0900 GB (72h) 8.6 ± 0.8 0.57 pCw39 352654097022301 20110830 0900 Radium-226 0.69 ± 0.065 0.019 pCw39 352654097022301 20110830 0900 Radium-228 0.47 ± 0.11 0.25 L pCw39 352654097022301 20110907 1130 Radon-222 1,040 ± 59 10.9 pCw39 352654097022301 20110830 0900 Uranium 306 0.004 D μw41 352632097024401 20110831 1200 GA (30d) 0.4 ± 0.36 0.47 ND pCw41 352632097024401 20110831 1200 GA (72h) 2 ± 0.42 0.36 pCw41 352632097024401 20110831 1200 GB (30d) 1 ± 0.4 0.6 pCw41 352632097024401 20110831 1200 GB (72h) 1.3 ± 0.29 0.43 pCw41 352632097024401 20110831 1200 Radium-226 0.133 ± 0.019 0.018 pCw41 352632097024401 20110831 1200 Radium-228 0.14 ± 0.11 0.2 ND pCw41 352632097024401 20110831 1200 Radon-222 95 ± 11 13.1 pCw41 352632097024401 20110831 1200 Uranium 0.12 0.004 μw42 352625097022401 20110926 1145 GA (30d) -0.2 ± 0.29 0.49 ND pCw42 352625097022401 20110926 1145 GA (72h) 0.9 ± 0.36 0.33 pCw42 352625097022401 20110926 1145 GB (30d) 0.9 ± 0.38 0.58 pCw42 352625097022401 20110926 1145 GB (72h) 1.2 ± 0.4 0.59 pCw42 352625097022401 20110926 1145 Radium-226 0.04 ± 0.01 0.013 pCw42 352625097022401 20110926 1145 Radium-228 0.22 ± 0.086 0.2 pCw42 352625097022401 20110926 1145 Radon-222 270 ± 20 13.9 pCw42 352625097022401 20110926 1145 Uranium 0.08 0.004 μw47 352609097033801 20110830 1230 GA (30d) 43 ± 5 0.97 pCw47 352609097033801 20110830 1230 GA (72h) 47 ± 5.4 0.81 B pCw47 352609097033801 20110830 1230 GB (30d) 8.8 ± 0.73 0.65 pCw47 352609097033801 20110830 1230 GB (72h) 2.4 ± 0.49 0.64 pCw47 352609097033801 20110830 1230 Radium-226 0.23 ± 0.028 0.018 pCw47 352609097033801 20110830 1230 Radium-228 0.2 ± 0.1 0.23 L pCw47 352609097033801 20110906 0900 Radon-222 380 ± 25 11.9 pC
Well ID USGS station ID Sample date YYYYMMDD Sample time Radiological constituent Result Sample-specific critical level Remark U

w47 352609097033801 20110830 1230 Uranium 26.3 0.004 μw48 352603097024901 20110823 1130 GA (30d) 24 ± 3.7 1.6 pCw48 352603097024901 20110823 1130 GA (72h) 23 ± 3 0.77 pCw48 352603097024901 20110823 1130 GB (30d) 6 ± 1 1.4 pCw48 352603097024901 20110823 1130 GB (72h) 1 ± 0.65 1 ND pCw48 352603097024901 20110823 1130 Radium-226 0.031 ± 0.0089 0.013 pCw48 352603097024901 20110823 1130 Radium-228 0.04 ± 0.11 0.26 ND pCw48 352603097024901 20110906 0900 Radon-222 169 ± 14 11.8 pCw48 352603097024901 20110823 1130 Uranium 19.7 0.004 μw50 352557097024101 20111005 1030 GA (30d) 39 ± 4.7 1.4 pCw50 352557097024101 20111005 1030 GA (72h) 37 ± 4.5 1.3 pCw50 352557097024101 20111005 1030 GB (30d) 7.4 ± 0.85 1 pCw50 352557097024101 20111005 1030 GB (72h) 1.3 ± 0.65 1 pCw50 352557097024101 20111005 1030 Radium-226 0.03 ± 0.01 0.011 pCw50 352557097024101 20111005 1030 Radium-228 0.3 ± 0.12 0.26 pCw50 352557097024101 20111005 1030 Radon-222 244 ± 19 13.8 pCw50 352557097024101 20111005 1030 Uranium 28.2 0.004 μw51 352553097021101 20110906 1430 GA (30d) 74 ± 8.3 1.3 pCw51 352553097021101 20110906 1430 GA (72h) 92 ± 10 0.85 pCw51 352553097021101 20110906 1430 GB (30d) 12 ± 1 0.94 pCw51 352553097021101 20110906 1430 GB (72h) 0.3 ± 0.6 0.87 ND pCw51 352553097021101 20110906 1430 Radium-226 0.086 ± 0.015 0.015 pCw51 352553097021101 20110906 1430 Radium-228 0.15 ± 0.11 0.22 ND pCw51 352553097021101 20110906 1430 Radon-222 237 ± 18 12 pCw51 352553097021101 20110906 1430 Uranium 48.3 0.004 μw56 352510097011201 20110831 1400 GA (30d) 9 ± 2 1.6 C pC

Appendix 3. Radionuclide concentrations measured in water samples collected from 20 private wells in part of the Kickapoo Tribe of Oklahoma Juricentral Oklahoma, 2011.—Continued[ID, identifier; USGS, U.S. Geological Survey; Result, radiological concentrations plus or minus the 1-sigma combined standard uncertainty; GA (30d), sample used for the 72-is counted a second time approximately 30 days after the initial count as referenced to a detector calibrated by using 230Thorium; ND, analyte not detected (concentration is lescal level); pCi/L, picocurie per liter; GA (72h), sample analyzed for gross alpha-particle activity at approximately 72 hours after sample collection as referenced to a detector calGB (30d), sample used for the 72-hour gross beta-particle analysis is counted a second time approximately 30 days after the initial count as referenced to a detector calibrated by sample analyzed for gross beta-particle activity at approximately 72 hours after sample collection as referenced to a detector calibrated by using 137Cesium; μg/L, micrograms method high range exceeded; B, laboratory background blank greater than the sample-specific critical level; C, sample-specific critical level exceeded the minimum detectable claboratory control sample recovery is outside acceptable range; ±, plus or minus]
Well ID USGS station ID Sample date YYYYMMDD Sample time Radiological constituent Result Sample-specific critical level Remark U

w56 352510097011201 20110831 1400 GA (72h) 12 ± 1.8 0.98 pCw56 352510097011201 20110831 1400 GB (30d) 2.4 ± 0.81 1.2 pCw56 352510097011201 20110831 1400 GB (72h) 1.4 ± 0.56 0.84 pCw56 352510097011201 20110831 1400 Radium-226 0.094 ± 0.017 0.014 pCw56 352510097011201 20110831 1400 Radium-228 0.2 ± 0.1 0.2 ND pCw56 352510097011201 20110913 1230 Radon-222 143 ± 12 11 pCw56 352510097011201 20110831 1400 Uranium 4.61 0.004 μw58 352417097015301 20110823 1400 GA (30d) 5.7 ± 1.2 0.91 pCw58 352417097015301 20110823 1400 GA (72h) 5.4 ± 0.94 0.64 pCw58 352417097015301 20110823 1400 GB (30d) 1.8 ± 0.49 0.71 pCw58 352417097015301 20110823 1400 GB (72h) 2.3 ± 0.34 0.46 pCw58 352417097015301 20110823 1400 Radium-226 0.4 ± 0.043 0.017 pCw58 352417097015301 20110823 1400 Radium-228 0.35 ± 0.13 0.25 pCw58 352417097015301 20111012 1100 Radon-222 410 ± 26 11.6 pCw58 352417097015301 20110823 1400 Uranium 1.62 0.004 μ
Appendix 4. Analytical relative percent difference for concentrations of major ions and trace elements (including uranium) in quality-control sampleblank results, for water samples collected from 20 private wells in part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, central Oklahoma, 2011[ID, identifier; mg/L, milligrams per liter; SiO2, silicon dioxide; RPD, relative percent difference; <, less than; μg/L, micrograms per liter; —, not calculated; RPD was not calcuestimated concentration or a concentration less than the minimum reporting level] Well ID Sample date YYYYMMDD Sample type Calcium, in mg/L Magnesium, in mg/L Potassium, in mg/L Sodium, in mg/L Chloride, in mg/L Fluoride, in mg/L Silic

i

w41 20110831 Environmental 11.1 4.42 0.93 9.37 15.8 0.04 15w41 20110831 Replicate 11.3 4.5 0.9 9.27 15.8 0.06 15RPD 1.79 percent 1.79 percent 3.3 percent 1.1 percent 0 40 percent 0w33 20110912 Environmental 5.34 2.35 1.31 140 29.7 0.82 9w33 20110912 Replicate 5.37 2.35 1.27 141 29.7 0.81 9RPD 0.6 percent 0 3.1 percent 0.7 percent 0 1.2 percent 0

Equipment blank <0.022 <0.011 <0.03 <0.06 <0.06 <0.04 <0

Well ID Sample date YYYYMMDD Sample type Antimony, in μg/L Arsenic, in μg/L Barium, in μg/L Beryllium, in μg/L Boron, in μg/L Bromide, in μg/L Cadmium, in μg/L 

w41 20110831 Environmental <0.03 0.07 61 0.18 29 0.13 <0.02 w41 20110831 Replicate <0.03 0.08 62 0.18 29 0.13 <0.02 RPD — 13.3 percent 1.6 percent — — 0 — w33 20110912 Environmental <0.03 0.54 68 0.04 2,050 0.12 <0.02 w33 20110912 Replicate <0.03 0.56 69 0.04 2,020 0.09 <0.02 RPD — 3.64 percent 1.46 percent 0 1.47 percent 28.6 percent — 

Equipment blank <0.027 <0.03 <0.07 <0.006 <3 <0.01 <0.016 
Well ID Sample date YYYYMMDD Sample type Copper, in μg/L Iron, in μg/L Lead, in μg/L Lithium, in μg/L Manganese, in μg/L Molybdenum, in μg/L Nickel, in μg/L 

w41 20110831 Environmental 21.6 3 0.14 7.4 0.4 <0.01 4.2 w41 20110831 Replicate 21.6 4 0.14 7.4 0.5 <0.01 4.2 

RPD 0 28.6 percent 0 0 22.2 percent — 0 

w33 20110912 Environmental <0.5 <3 <0.01 6.6 4.3 1.57 <0.09 w33 20110912 Replicate <0.5 5 <0.01 6.8 4.3 1.57 <0.09 

RPD — — — 3 percent 0 0 — 

Equipment 

blank <0.8 <3.2 <0.025 <0.22 <0.13 <0.014 <0.09 

Well ID Sample date YYYYMMDD Sample type Strontium, in μg/L Thallium, in μg/L Uranium, in μg/L Vanadium, in μg/L Zinc, in μg

w41 20110831 Environmental 82.8 <0.01 0.08 0.26 2.3w41 20110831 Replicate 83.2 <0.01 0.12 0.27 2.3RPD 0.5 percent — 40 percent 3.8 percent 0w33 20110912 Environmental 87.8 <0.01 1.09 <0.08 <1.4w33 20110912 Replicate 87.8 <0.01 1.11 <0.08 <1.4RPD 0 — 1.8 percent — —

Equipment 

blank <0.2 <0.01 <0.004 <0.08 <1.4
Appendix 5. Analytical relative percent difference for concentrations of radionuclides (not including uranium) in quality-control samples for water sprivate wells in part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, central Oklahoma, 2011. [ID, identifier; Result, radiological concentrations plus or minus the 1-sigma combined standard uncertainty; RPD, relative percent difference; RPD was not calculated if one connot calculated; pCi/L, picocurie per liter; GA (72h), sample analyzed for gross alpha-particle activities at approximately 72 hours after sample collection as referenced to a detecrium; B, laboratory background blank greater than the sample-specific critical level; GA (30d), sample used for the 72-hour gross alpha-particle analysis is counted a second timthe initial count as referenced to a detector calibrated by using 230Thorium; ND, not detected; GB (72h), sample analyzed for gross beta-particle activities at approximately 72 hreferenced to a detector calibrated by using 137Cesium; GB (30d), sample used for the 72-hour gross beta-particle analysis is counted a second time approximately 30 days after a detector calibrated by using 137Cesium; ±, plus or minus] Well ID Quality control sample type Sample date YYYYMMDD Radiological constituent Result Sample-specific critical level Remark RPD 

w41 Environmental 20110831 Radium-226 0.133±0.019 0.018 13.6 perw41 Replicate 20110831 Radium-226 0.116±0.018 0.016 w33 Environmental 20110912 Radium-226 1.2±0.1 0.016 11.4 perw33 Replicate 20110912 Radium-226 1.07±0.097 0.016 w41 Environmental 20110831 GA (72h) 2±0.42 0.36 16.2 perw41 Replicate 20110831 GA (72h) 1.7±0.35 0.24 w33 Environmental 20110912 GA (72h) 5±1.1 0.93 B 41.3 perw33 Replicate 20110912 GA (72h) 7.6±1.4 0.95 B w41 Environmental 20110831 GA (30d) 0.4±0.36 0.47 — w41 Replicate 20110831 GA (30d) 0±0.31 0.49 ND w33 Environmental 20110912 GA (30d) 11.1±1.7 0.82 0.9 perw33 Replicate 20110912 GA (30d) 11±1.7 0.82 w41 Environmental 20110831 GB (72h) 1.3±0.29 0.43 16.7 perw41 Replicate 20110831 GB (72h) 1.1±0.33 0.5 w33 Environmental 20110912 GB (72h) 2.8±0.52 0.73 11.3 perw33 Replicate 20110912 GB (72h) 2.5±0.57 0.81 w41 Environmental 20110831 GB (30d) 1±0.4 0.6 — w41 Replicate 20110831 GB (30d) 0.6±0.44 0.7 ND 
Well ID Quality control sample type Sample date YYYYMMDD Radiological constituent Result Sample-specific critical level Remark RPD w33 Environmental 20110912 GB (30d) 3.5±0.54 0.71 2.9 perw33 Replicate 20110912 GB (30d) 3.4±0.52 0.68 w41 Environmental 20110831 Radium-228 0.14±0.11 0.2 60 percw41 Replicate 20110831 Radium-228 0.26±0.096 0.19 w33 Environmental 20110912 Radium-228 0.53±0.11 0.23 18.6 perw33 Replicate 20110912 Radium-228 0.44±0.11 0.23 w41 Environmental 20110831 Radon-222 95±11 13.117 8.1 perw41 Replicate 20110831 Radon-222 103±12 13.2773 w33 Environmental 20110912 Radon-222 1,220±69 11.9307 3.2 perw33 Replicate 20110912 Radon-222 1,260±71 12.0823 
48 Groundwater Quality in Water Samples Collected in Part of the Kickapoo Tribe of Oklahoma Jurisdictional Area, 2011

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