U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2015–5182

Prepared in cooperation with the Citizen Potawatomi Nation

Summary of U.S. Geological Survey Studies Conducted in 

Cooperation with the Citizen Potawatomi Nation, Central 

Oklahoma, 2011–14
Cover, Water tower located in the Citizen Potawatomi Nation Tribal Jurisdictional Area, Shawnee, 

Oklahoma. Photograph by Michael Dotson, Citizen Potawatomi Nation.
Summary of U.S. Geological Survey Studies 

Conducted in Cooperation with the Citizen 

Potawatomi Nation, Central Oklahoma, 

2011–14

By William J. Andrews, Carol J. Becker, Derek W. Ryter, and S. Jerrod Smith

Prepared in cooperation with the Citizen Potawatomi Nation

Scientific Investigations Report 2015–5182

U.S. Department of the Interior

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

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Director

U.S. Geological Survey, Reston, Virginia: 2016

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Suggested citation:

Andrews, W.J., Becker, C.J., Ryter, D.W., and Smith, S.J., 2016, Summary of U.S. Geological Survey studies conducted 

in cooperation with the Citizen Potawatomi Nation, central Oklahoma, 2011–14: U.S. Geological Survey Scientific 

Investigations Report 2015–5182, 22 p., http://dx.doi.org/10.3133/sir20155182.

ISSN 2328-031X (print)

ISSN 2328-0328 (online)
iii

Acknowledgments

The authors thank Jim Collard, Kelley Francen, Shawn Howard, Richard Kunze, Kurtis Silas, 

and Karen Fulbright of the Citizen Potawatomi Nation for providing support and advice for 

the retrospective analysis of data, water-quality sample collection and analysis, groundwater 

modeling, and measurement of groundwater and surface-water relations. Thanks are expressed 

to the Administration for Native Americans of the U.S. Department of Health and Human 

Services for providing support for the projects conducted in cooperation with the Citizen 

Potawatomi Nation. We also are grateful to the many landowners who allowed access to their 

properties for collection of water samples.

v

Contents

Acknowledgments .......................................................................................................................................iii

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

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

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

Study Area Setting ...............................................................................................................................2

Climate ...................................................................................................................................................2

Land Cover ............................................................................................................................................2

Hydrogeology .................................................................................................................................................2

Water Quality .................................................................................................................................................4

Groundwater/Surface-Water Simulations ..............................................................................................11

Summary .......................................................................................................................................................19

References Cited .........................................................................................................................................20

Figures

1. Map showing land cover in the Citizen Potawatomi Nation Tribal Jurisdictional 

Area, central Oklahoma, 2006 ....................................................................................................3

2. Graph showing annual mean streamflow at four long-term streamflow-gaging 

stations in central Oklahoma, October 1984 through September 2011 ...............................4

3. Map showing surficial geology and locations of 4 stream sites and 30 wells 

sampled in and near the Citizen Potawatomi Nation Tribal Jurisdictional Area, 

central Oklahoma, 2012–13 ........................................................................................................5

4. Graphs showing nutrient concentrations measured in water samples collected 

at four stream sites in central Oklahoma, 2012–13, in relation to streamflow ...................9

5. Graphs showing number of detections of 69 organic compounds measured in 

water samples collected at 4 stream sites in central Oklahoma, 2012–13, with 

streamflow and of categories that include fecal indicators and plant sterols, 

polycyclic aromatic hydrocarbons, and 5 categories of synthetic organic 

compounds: detergent metabolites, industrial compounds, pesticides, personal 

care products, and fire retardants ..........................................................................................10

6. Map showing location of the Citizen Potawatomi Nation Tribal Jurisdictional 

Area, hydrological features, and the Central Oklahoma and alluvial aquifers in 

central Oklahoma .......................................................................................................................12

7. Map showing Citizen Potawatomi Nation numerical groundwater-flow model 

active area with the 1986–87 potentiometric surface, steady-state head 

residuals, locations of model features, and the inset model domain for the Citizen 

Potawatomi Nation Tribal Jurisdictional Area in central Oklahoma .................................13

8. Graph showing transient measured groundwater heads and simulated 

groundwater heads for the Citizen Potawatomi Nation numerical groundwaterflow model, central Oklahoma .................................................................................................14

9. Graphs showing simulated and estimated streamflows for North Canadian 

River streamflow-gaging stations, 1988–2009 .......................................................................15
vi

10. Map showing inset model active area, top active layer, and boundary condition 

cells and locations of economic development zones simulated for sustainable 

yields, Citizen Potawatomi Nation Tribal Jurisdictional Area, central Oklahoma ..........16

11. Map showing Groundwater Management Process managed wells, optimized 

pumping rates, and resulting effects on induced infiltration by stream reach 

number at the Iron Horse Industrial Park, Citizen Potawatomi Nation Tribal 

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

12. Graph showing normal streamflow and streamflow during a simulated drought 

from 1990 to 2000 at the North Canadian River at Shawnee, Oklahoma, 

streamflow-gaging station, with percent change during and after the simulated 

drought ........................................................................................................................................19

Tables

1. Stream-site information and land use and land cover in the upstream drainage 

basins of four stream sites sampled in and near the Citizen Potawatomi Nation 

Tribal Jurisdictional Area, central Oklahoma, 2012–13 .........................................................7

2. Characteristics of 30 wells sampled in and near the Citizen Potawatomi Nation 

Tribal Jurisdictional Area, central Oklahoma, 2012–13 .........................................................8
vii

Conversion Factors

Inch/Pound to International System of Units

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2)

acre 0.004047 square kilometer (km2)

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

Volume

gallon (gal) 3.785 liter (L) 

cubic foot (ft3) 0.02832 cubic meter (m3) 

acre-foot (acre-ft) 1,233 cubic meter (m3)

Flow rate

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

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

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

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as °F = (1.8 × 

°C) + 32.

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as °C = (°F – 

32) / 1.8.

Datum

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.

Supplemental Information

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 in either milligrams per liter (mg/L) 

or micrograms per liter (μg/L).
viii

Abbreviations

EDZ economic development zone

ET evapotranspiration 

MCL Maximum Contaminant Level

OWRB Oklahoma Water Resources Board

R2 coefficient of determination

SMCL Secondary Maximum Contaminant Level

USGS U.S. Geological Survey
Summary of U.S. Geological Survey Studies Conducted in 

Cooperation with the Citizen Potawatomi Nation, Central 

Oklahoma, 2011–14

By William J. Andrews, Carol J. Becker, Derek W. Ryter, and S. Jerrod Smith

Abstract

The U.S. Geological Survey conducted hydrologic 

studies and published three U.S. Geological Survey scientific 

investigations reports in cooperation with the Citizen 

Potawatomi Nation from 2011 to 2014 to characterize the 

quality and quantity of water resources. The study areas of 

those reports consisted of approximately 960 square miles in 

parts of three counties in central Oklahoma. This study area 

has multiple abundant sources of water, being underlain by 

three principal aquifers (alluvial/terrace, Central Oklahoma, 

and Vamoosa-Ada), being bordered by two major rivers 

(North Canadian and Canadian), and having several smaller 

drainages including the Little River in the central part of 

the study area and Salt Creek in the southeastern part of the 

study area. The Central Oklahoma aquifer (also referred to 

as the “Garber-Wellington aquifer”) underlies approximately 

3,000 square miles in central Oklahoma in parts of Cleveland, 

Logan, Lincoln, Oklahoma, and Pottawatomie Counties and 

much of the study area. Water from these aquifers is used for 

municipal, industrial, commercial, agricultural, and domestic 

supplies.

Much of the water in the study area is of good quality; 

however, in some parts of this area water quality was impaired 

by very hard surface water and groundwater, large chloride 

concentrations in some smaller streams, relatively large 

concentrations of nitrogen and phosphorus nutrients and 

large counts of fecal-indicator bacteria in the North Canadian 

River, and uranium concentrations that exceeded the U.S. 

Environmental Protection Agency Maximum Contaminant 

Level of 30 micrograms per liter for public water supplies in 

water samples collected from a small number of wells. Most 

stream-water samples collected from the Little River by the 

U.S. Geological Survey in 2012–13 had dissolved solids 

concentrations exceeding the U.S. Environmental Protection 

Agency Secondary Maximum Contaminant Level for public 

water supplies of 500 milligrams per liter. Larger numbers of 

organic compounds were measured in water samples collected 

from the North Canadian River than the Little River.

Numerical groundwater-flow models were created to 

characterize flow systems in aquifers underlying this study 

area and areas of particular interest within the study area. 

Those models were used to estimate sustainable groundwater 

yields from parts of the North Canadian River alluvial 

aquifer, characterize groundwater/surface-water interactions, 

and estimate the effects of a 10-year simulated drought on 

streamflows and water levels in alluvial and bedrock aquifers. 

Pumping of wells at the Iron Horse Industrial Park was 

estimated to cause negligible infiltration of water from the 

adjoining North Canadian River. A 10-year simulated drought 

of 50 percent of normal recharge was tested for the period 

1990–2000. For this period, the total amount of groundwater 

in storage was estimated to decrease by 8.6 percent in the 

North Canadian River alluvial aquifer and approximately 

0.2 percent in the Central Oklahoma aquifer, and groundwater 

flow to streams was estimated to decrease by 28–37 percent. 

This volume of groundwater loss showed that the Central 

Oklahoma aquifer is a bedrock aquifer that has relatively low 

rates of recharge from the land surface. The simulated drought 

decreased simulated streamflow, composed of base flow, in 

the North Canadian River at Shawnee, Okla., which did not 

recover to predrought conditions until the relatively wet year 

of 2007 after the simulated drought period.

Introduction

The Citizen Potawatomi Nation (CPN) was interested 

in better characterizing water resources associated with 

tribal-owned lands in central Oklahoma. The U.S. Geological 

Survey (USGS), in cooperation with the CPN, conducted 

studies of the occurrence and distribution of water resources, 

water quality, and simulations of groundwater and surfacewater systems in a 960-square-mile area of central Oklahoma 

from 2011 to 2014.
2 Summary of USGS Studies Conducted in Cooperation with the CPN, Central Oklahoma, 2011–14

Purpose and Scope

This report summarizes highlights of previously 

published USGS scientific investigations reports of historical 

hydrologic data and estimates of water resources and gaps 

in existing data (Andrews and others, 2013), groundwater 

and surface-water quality (Becker, 2014), and simulations 

of groundwater and surface-water flow systems (Ryter and 

others, 2015) in a 960-square-mile area of central Oklahoma. 

The CPN wanted these types of information to better 

understand the hydrologic resources of lands that their Nation 

owns and of surrounding areas.

Study Area Setting

The study area described in this report is in parts of 

Cleveland, Oklahoma, and Pottawatomie Counties in central 

Oklahoma (fig. 1). The study area has abundant water 

resources, being drained by the North Canadian River, which 

defines the northern border, the Canadian River, which defines 

the southern border, the Little River, which flows through the 

central part, and Salt Creek, which flows in the southeastern 

part of the study area (fig. 1). All major streams in the study 

area flow from west to east. The study area is underlain by 

unconsolidated alluvial and terrace aquifers along those rivers 

and by the consolidated Central Oklahoma and Vamoosa-Ada 

aquifers (Andrews and others, 2013).

Climate

The study area has a temperate continental climate, 

receiving an average of approximately 40 inches per year 

(in/yr) of precipitation from 1981 to 2010 and having 

approximately 50 in/yr of free-surface evaporation (Oklahoma 

Climatological Survey, 2011a, b). Precipitation typically 

occurs from March through June and from September through 

November (Oklahoma Climatological Survey, 2011b). 

Monthly average air temperatures from 1981 to 2010 ranged 

from 35.9 degrees Fahrenheit (°F) in January to 81.5 °F in July 

(Oklahoma Climatological Survey, 2011a).

Land Cover

The predominant types of land cover in the study area 

as of 2006 were deciduous forest and shrubs and natural 

grassland, which are most common in the central part 

of the study area (fig. 1; U.S. Geological Survey, 2012). 

Cultivated crops and pasture or hay were predominant landcover types on flatter land along major streams and in the 

southwestern part of the study area (fig. 1; U.S. Geological 

Survey, 2012).

Hydrogeology

Annual mean streamflows at three sites in the study area 

generally decreased from peaks in the late 1980s (fig. 2). 

Streamflows at four sites in the study area recently peaked in 

water year 2007–8 but declined to near long-term low flows by 

water year 2011 (fig. 2). A water year is the 12-month period 

October 1 through September 30 designated by the calendar 

year in which it ends. 

Groundwater also is an important source of water in 

the study area. The principal aquifers in the study area are 

alluvial and terrace aquifers along the North Canadian and 

Canadian Rivers, referred to herein as “alluvial aquifers,” 

and the Central Oklahoma aquifer, composed of the Garber 

Sandstone, Wellington Formation, and Chase, Council Grove, 

and Admire Groups (fig. 3). Alluvial aquifers are the thinnest 

aquifers in the area, generally being less than 100 feet (ft) 

thick, compared to thicknesses of several hundred to more 

than 1,000 ft of bedrock aquifers underlying the study area 

(Andrews and others, 2013). Despite being relatively thin, 

alluvial aquifers in the study area produce some of the highest 

well yields, in some cases exceeding 1,000 gallons per minute 

(gal/min; Andrews and others 2013). The Central Oklahoma 

aquifer (also referred to as the “Garber-Wellington aquifer”) 

underlies approximately 3,000 square miles in central 

Oklahoma in parts of Cleveland, Logan, Lincoln, Oklahoma, 

and Pottawatomie Counties and much of the study area. Wells 

completed in the Central Oklahoma aquifer, which underlies 

most of the area, typically produce 25–50 gal/min (Bingham 

and Moore, 1975). Wells completed in the Vamoosa-Ada 

aquifer, which underlies the Vanoss Formation in the 

easternmost part of the study area and is not a major aquifer 

(fig. 3), generally produce less than 25 gal/min (Bingham and 

Moore, 1975). Groundwater levels in the Central Oklahoma 

aquifer decreased from about 32 ft below land surface in 1987 

to 35.8 ft below land surface in 2009 (Christenson and others, 

1992; Mashburn and Magers, 2011).
Hydrogeology 3

0 2 4 8 MILES

0 2 4 6 8 KILOMETERS

6

EXPLANATION

Land cover

 Open water

 Lawn grasses

 Developed, low intensity

 Developed, medium intensity

 Developed, high intensity

 Barren land

 Deciduous forest

 Evergreen forest

 Shrubs and natural grassland

 Pasture or hay

 Cultivated crops

 Emergent herbaceous wetlands

Citizen Potawatomi Nation Tribal

 Jurisdictional Area boundary

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

Universal Transverse Mercator, zone 14

North American Datum of 1983

Land-cover data from Multi-Resolution Land Characteristics Consortium

National Land Cover Database (U.S. Geological Survey, 2012)

97°00' 96°40' 97°20'

35°20'

35°00'

SEMINOLE

COUNTY

POTTAWATOMIE

COUNTY

PONTOTOC

COUNTY

CLEVELAND

COUNTY

LINCOLN

COUNTY

OKLAHOMA

COUNTY

OKFUSKEE COUNTY

MCCLAIN

COUNTY

Horseshoe

Lake

Stanley

Draper

Lake

Lake

 Thunderbird

Shawnee

Reservoir

Wes Watkins

Reservoir

Canadian River

North Canadian River

Salt Creek

OKLAHOMA

Map area

Citizen Potawatomi Nation

Tribal Jurisdictional Area

Figure 1. Land cover in the Citizen Potawatomi Nation Tribal Jurisdictional Area, central Oklahoma, 2006 (modified from Andrews and 

others, 2013).
4 Summary of USGS Studies Conducted in Cooperation with the CPN, Central Oklahoma, 2011–14

Water Quality

Retrospective analysis of water-quality data collected by 

the USGS and State and tribal agencies from 1985 to 2011 

(Andrews and others, 2013) indicated the following general 

features about water quality in the study area:

1. Total dissolved solids concentrations in more than 

half of the surface-water samples collected in this 

area exceeded the U.S. Environmental Protection 

Agency (EPA) Secondary Maximum Contaminant 

Level (SMCL) of 500 milligrams per liter (mg/L; U.S. 

Environmental Protection Agency, 2011a). Numerous 

samples in the Salt Creek watershed in the southeastern 

part of the study area (fig. 3) had total dissolved solids 

concentrations greater than 1,000 mg/L. Hardness, which 

commonly is positively correlated to total dissolved 

solids concentration, is an indication of the likelihood 

of water to form carbonate mineral deposits in pipes and 

boilers. More than three-quarters of the surface-water 

samples and most of the groundwater samples collected 

in this study area were very hard.

2. Chloride concentrations exceeded the EPA SMCL of 

250 mg/L (U.S. Environmental Protection Agency, 

2011a) in most surface-water samples collected in 

the Salt Creek watershed. Chloride concentrations in 

those samples also exceeded the Criterion Continuous 

Concentration set to protect aquatic life (230 mg/L; 

U.S. Environmental Protection Agency, 2002). Chloride 

concentrations exceeding that standard can contribute 

salty taste to water, elevate blood pressure, harm plants 

and aquatic biota, and increase corrosiveness of water to 

metal pipes (Wesson, 1969; Fadeeva, 1971; Maas, 1987; 

World Health Organization, 1996).

3. Total phosphorus concentrations in surface-water 

samples collected from the North Canadian River were 

greater than criteria set to minimize eutrophication 

(excessive growth of algae and other aquatic plants) 

in surface water, such as the 0.037 mg/L standard 

set for Scenic Rivers in northeast Oklahoma, and the 

0.075 mg/L standard set by the State of Wisconsin for 

most streams in that state (State of Oklahoma, 2006; 

State of Wisconsin, 2010).

4. Numbers of fecal-coliform bacteria, which are associated 

with animal feces, in water samples collected at nine 

sites on the North Canadian River exceeded the primary 

contact standard of 200 colonies per 100 milliliters 

(geometric mean of 5 samples in 30 days; State of 

Oklahoma, 2006) in 10–70 percent of those samples.

5. Twenty to twenty-five percent of groundwater samples 

collected from alluvial aquifers and the Central 

Oklahoma aquifer were more acidic than the EPA SMCL 

for pH of 6.5 (U.S. Environmental Protection Agency, 

2011a). That SMCL was set to minimize corrosion of 

metals from pipes.

6. Potassium, sodium, fluoride, and bicarbonate 

concentrations were significantly greater in water 

samples collected from the Vamoosa-Ada aquifer in the 

eastern edge of the study area than in samples from the 

other aquifers. Concentrations of these ions increased 

with well depths. 

Water year

1985 1990 1995 2000 2005 2010

Annual mean streamflow, in cubic feet per second

2,500

2,000

1,500

1,000

500

0

EXPLANATION

07241550 North Canadian River near Harrah, Okla.

07241800 North Canadian River at Shawnee, Okla.

07230500 Little River near Tecumseh, Okla.

07229200 Canadian River at Purcell, Okla.

Figure 2. Annual mean streamflow at four long-term streamflow-gaging stations in central Oklahoma, October 1984 through 

September 2011 (modified from Andrews and others, 2013).
Water Quality 5

OKLAHOMA

Map area

Citizen Potawatomi Nation

Tribal Jurisdictional Area

Quaternary-age geologic unit

Permian-age geologic unit

Pennsylvanian-age geologic unit

EXPLANATION

Lake

Thunderbird

Wes Watkins 

Reservoir

Horseshoe 

Lake

POTTAWATOMIE

COUNTY

CLEVELAND

COUNTY

LINCOLN COUNTY

OKLAHOMA

COUNTY

w1

w2

w3

w4 w5

w6

w8 w7

w9

w10

w11

w12 w13

w14

w15

w16

w17 w18

w19

w20

w21

w22

w23

w24

w25 w26

w27

w28 w29

w30

97°20’ 97°

35°20’

35°

96°40’

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

Albers Equal-Area Conic projection,

North American Datum of 1983

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

Alluvium

Terrace deposits

Vanoss Formation

Garber Sandstone

Wellington Formation

Chase, Council Grove, and Admire 

Groups (undivided)

Citizen Potawatami Nation Tribal 

Jurisdictional Area boundary

Well and identifier—Sample collected for 

chemical analysis (table 2)

U.S. Geological Survey streamflow-gaging 

station and stream-water-quality site 

and identifier (table 1)

Stream-water-quality site and identifier 

without gage (table 1)

North Canadian River

near Harrah, Oklahoma

07241550

North Canadian 

River at Shawnee, 

Oklahoma

07241800

Little River 

near Tecumseh, 

Oklahoma

07230500

Deer Creek near

McLoud, Oklahoma

07241590

Stanley

 Draper

 Lake 

Little River

Canadian River

North Canadian River

0 2.5 5 7.5 10 MILES

0 2.5 5 7.5 10 KILOMETERS

w29

07230500

07241590

Salt Creek

Harrah

McLoud

Shawnee

Tecumseh

SEMINOLE

COUNTY

MCCLAIN COUNTY PONTOTOC

COUNTY

Figure 3. Surficial geology and locations of 4 stream sites and 30 wells sampled in and near the Citizen Potawatomi Nation Tribal 

Jurisdictional Area, central Oklahoma, 2012–13 (from Becker, 2014).
6 Summary of USGS Studies Conducted in Cooperation with the CPN, Central Oklahoma, 2011–14

Becker (2014) provided an updated assessment of 

surface-water and groundwater quality; sampling described 

in that report was conducted for constituents that had not 

been analyzed in previous studies and in areas not previously 

sampled. A total of 4 stream sites were sampled repeatedly, 

and 30 wells were sampled once in the study area from 2012 

to 2013 (Becker, 2014; tables 1 and 2). Water-quality data 

collected from those sites can be downloaded from the USGS 

National Water Information System (U.S. Geological Survey, 

2015). Notable results from that report related to surface-water 

quality include the following:

1. The largest concentrations of total dissolved solids 

and chlorides were measured in stream-water samples 

collected at the Little River near Tecumseh, Okla., 

streamflow-gaging station. The EPA SMCL for total 

dissolved solids in drinking water of 500 mg/L was 

exceeded in 7 of 8 stream-water samples collected at 

that station. The 250-mg/L EPA SMCL for chloride was 

exceeded in 5 of the 8 stream-water samples collected at 

that station.

2. Median concentrations of total dissolved nitrogen were 

about an order of magnitude higher in stream-water 

samples collected at the two streamflow-gaging stations 

on the North Canadian River than concentrations in 

stream-water samples collected at the Little River near 

Tecumseh, Okla., streamflow-gaging station and the 

Deer Creek site (fig. 4). Median concentrations of total 

dissolved phosphorus were higher by about two orders of 

magnitude in stream-water samples collected at the two 

streamflow-gaging stations on the North Canadian River 

than concentrations in stream-water samples collected 

at the Little River near Tecumseh, Okla., streamflowgaging station and the Deer Creek site and typically 

exceeded previously described water-quality standards 

for total dissolved phosphorus in streams. Dissolved 

concentrations of total nitrogen, orthophosphorus, and 

total phosphorus were largest in stream-water samples 

collected at the two North Canadian River streamflowgaging stations at low streamflows, indicating that 

wastewater effluent discharged upstream may have been 

a notable source of these nutrients.

3. Concentrations of most trace elements increased 

with increasing streamflow in stream-water samples 

collected at the two North Canadian River streamflowgaging stations, indicating that most trace elements are 

washed into the river by runoff from the land surface 

or resuspended from streambed sediments. Most 

trace-element concentrations were less than Maximum 

Contaminant Levels (MCLs) set for public drinkingwater supplies (U.S. Environmental Protection Agency, 

2011b).

4. A greater number of organic compounds were detected 

in stream-water samples collected at the two streamflowgaging stations on the North Canadian River than in 

stream-water samples collected at the streamflow-gaging 

station on the Little River near Tecumseh, Okla., and the 

Deer Creek site (fig. 5).

Notable results from Becker (2014) related to 

groundwater quality include the following:

1. Groundwater in the study area was very hard, with a 

median concentration of 180 mg/L as calcium carbonate 

in water samples collected from the 30 wells. Dissolved 

solids concentrations exceeded the 500-mg/L SMCL 

in 9 of the 30 groundwater samples. Trace-element 

concentrations, except for uranium, did not exceed 

MCLs in the groundwater samples.

2. Two of the 30 groundwater samples had uranium 

concentrations exceeding the MCL of 30 micrograms per 

liter (μg/L) with concentrations of 79.5 and 31.1 μg/L. 

Uranium concentrations were highest in water samples 

collected from wells completed in the Wellington 

Formation and the Chase, Council Grove, and Admire 

Groups in the southern and eastern parts of the study 

area.
Table 1. Stream-site information and land use and land cover in the upstream drainage basins of four stream sites sampled in and near the Citizen PJurisdictional Area, central Oklahoma, 2012–13 (from Becker, 2014).[USGS, U.S. Geological Survey; ft3/s, cubic feet per second; –, not applicable; streamflow is by calendar year; annual mean streamflow calculated for years with complete data ocontinuous streamflow measured by real-time monitor]

USGS 

streamflowgaging station 

and number

Upstream drainage 

area/contributing 

drainage area 

(square miles)

Annual mean 

streamflow (ft3/s) 

(years of record)a

Mean daily 

streamflow 

Jan. 1–Dec. 31, 2012 

(ft3/s)a

Lowest streamflow/highest 

streamflow Jan. 1–Dec. 31, 2012 

(ft3/s)a

Information collected 

during study

Little River near 

Tecumseh, Oklahoma(07230500)

463/463 143

 (1966 to 2013)

12.7 0 (July 21 through August 18)/1,260 

(March 19)

8 water-quality samples; 

8 water-property measurements; 8 streamflow measurements

44 

North Canadian 

River near Harrah, Oklahoma (07241550)

13,775/10,278 488 

(1969 to 2011)

180 39 (November 11)/4,270 (March 20) 8 water-quality samples; 

8 water-property measurements; 8 streamflow measurements; realtime measurements of water properties and streamflow

62 

Deer Creek near 

McLoud, Oklahoma (07241590)

40 Not gaged – – 3 water-quality samples; 

3 water-property measurements; 2 streamflow measurements

39 

North Canadian 

River at Shawnee, Oklahoma (07241800)

14,005/10,508 524 

(2002 to 2011)

246 30 (August 5)/4,860 (April 18) 8 water-quality samples; 

8 water-property measurements; 8 streamflow measurements

62 

aU.S. Geological Survey (2013).bFry and others (2011).
8 Summary of USGS Studies Conducted in Cooperation with the CPN, Central Oklahoma, 2011–14

Table 2. Characteristics of 30 wells sampled in and near the Citizen Potawatomi Nation Tribal Jurisdictional Area, central Oklahoma, 

2012–13 (modified from Becker, 2014).

[ID, identifier; USGS, U.S. Geological Survey; NAVD 88, North American Vertical Datum of 1988; GBWG, Garber-Wellington aquifer; ALVM, alluvial 

aquifer; TTRC, terrace aquifer; CCGA, Chase, Council Grove, and Admire Groups; VNSS, Vanoss Formation]

Well ID USGS 

station ID

Land surface altitude 

(feet above NAVD 88)

Well depth 

(depth in feet 

below land surface)

Water 

use Aquifer

w1 352755097141801 1,210 240 Domestic GBWG

w2 352527097144201 1,244 120 Domestic GBWG

w3 352449097054601 1,099 110 Domestic GBWG

w4 352412097040301 1,093 170 Domestic GBWG

w5 352407096462701 907 42 Unused ALVM

w6 352303097033401 1,031 220 Commercial GBWG

w7 352232097035501 1,073 60 Domestic TTRC

w8 352226097073901 1,161 160 Domestic GBWG

w9 352104097044701 1,101 200 Domestic GBWG

w10 352002097000301 1,079 160 Domestic CCGA

w11 351937096512201 993 100 Domestic VNSS

w12 351819097071201 1,178 160 Domestic GBWG

w13 351807096545801 991 80 Industrial ALVM

w14 351751096563301 1,002 195 Domestic CCGA

w15 351649096584801 1,077 90 Domestic CCGA

w16 351634097025601 1,152 170 Domestic GBWG

w17 351536096545501 1,072 165 Domestic CCGA

w18 351518096511501 1,080 200 Domestic VNSS

w19 351448097024501 1,092 160 Domestic GBWG

w20 351422097072801 1,038 140 Domestic GBWG

w21 351251097000801 1,013 220 Domestic GBWG

w22 351103096534601 914 70 Stock ALVM

w23 350624097005601 1,101 80 Domestic GBWG

w24 350603097065901 1,117 176 Domestic GBWG

w25 350236097191501 1,088 360 Domestic GBWG

w26 350234097040401 1,032 80 Domestic GBWG

w27 350117096591001 1,044 260 Domestic GBWG

w28 350034097031201 1,103 141 Domestic GBWG

w29 350017096595501 1,012 80 Domestic GBWG

w30 345816097095101 1,102 200 Domestic GBWG
Water Quality 9

EXPLANATION

Little River near Tecumseh, Oklahoma (07230500) 

North Canadian River near Harrah, Oklahoma (07241550)

North Canadian River at Shawnee, Oklahoma (07241800) 

Deer Creek near McLoud, Oklahoma (07241590)

Nationwide median concentration reported by

Dubrovsky and Hamilton (2010)

Oklahoma standard for scenic rivers (0.037)

(Oklahoma Water Resources Board, 2013)

0.001

0.01

0.1

1

10

Streamflow, in cubic feet per second

D

0.1

1

10

Total nitrogen (dissolved), calculated,

in milligrams per liter

Background

Agricultural streams

Urban streams

A

0.001

0.01

0.1

1

10

Total phosphorus (dissolved), in milligrams per liter

Background

Agricultural and urban streams

C

Orthophosphorus (dissolved),

in milligrams per liter as phosphorus 0.01

0.1

1

0.1 1 10 100 1,000 10,000

A

m

monia nitrogen (dissolved),

in milligrams per liter as nitrogen

B

0.1 1 10 100 1,000 10,000

Streamflow, in cubic feet per second

Figure 4. Nutrient concentrations measured in water samples collected at four stream sites in central Oklahoma, 2012–13, in 

relation to streamflow (from Becker, 2014). A, Total dissolved nitrogen. B, Dissolved ammonia nitrogen. C, Total dissolved phosphorus. 

D, Dissolved orthophosphorus.
10 Summary of USGS Studies Conducted in Cooperation with the CPN, Central Oklahoma, 2011–14

0

5

10

15

20

25

30

35

40

1 10 100 1,000

A

Number of detections

0

10

15

20

25

30

35

40

45

50

B

5

10,000

Number of detections

0.1

Little River near Tecumseh, 

Oklahoma (07230500)

North Canadian River near Harrah, 

Oklahoma (07241550)

Deer Creek near McLoud, 

Oklahoma (07241590)

North Canadian River at Shawnee, 

Oklahoma (07241800)

EXPLANATION

Little River near Tecumseh, Oklahoma (07230500)

8 samples collected, 59 detections

North Canadian River near Harrah, Oklahoma 

(07241550)

8 samples collected, 213 detections

North Canadian River at Shawnee, Oklahoma 

(07241800)

8 samples collected, 203 detections

Deer Creek near McLoud, Oklahoma (07241590)

3 samples collected, 25 detections

Quality-assurance equipment-blank sample

2 samples collected, 8 detections

Number of compounds analyzed in category

EXPLANATION

(5)

Compound

Streamflow, in cubic feet per second

Fecal indicators and 

Detergent metabolites (8)

plant sterols (8)

Polycyclic aromatic 

hydrocarbons (11)

Industrial compounds (14)

Pesticides (11)

Personal care products (12)

Fire retardants (5)

Figure 5. Number of detections of 69 organic compounds measured in water samples collected at 4 stream sites in central Oklahoma, 

2012–13, A, with streamflow and B, of categories that include fecal indicators and plant sterols, polycyclic aromatic hydrocarbons, and 

5 categories of synthetic organic compounds: detergent metabolites, industrial compounds, pesticides, personal care products, and fire 

retardants (from Becker, 2014).
Groundwater/Surface-Water Simulations 11

Groundwater/Surface-Water 

Simulations

The USGS, in cooperation with the CPN, evaluated 

groundwater resources and connections between groundwater 

and surface water by using the MODFLOW-NWT program 

(Niswonger and others, 2011) for steady-state and transient 

simulations. By using hydrogeologic information from the 

numerical groundwater-flow model of the Central Oklahoma 

aquifer described in Mashburn and others (2013), referred 

to in this report as the “Central Oklahoma aquifer model,” 

a numerical groundwater-flow model was constructed that 

covered the CPN Tribal Jurisdictional Area. To accomplish 

this task, the part of the Central Oklahoma aquifer model 

that covered the CPN Tribal Jurisdictional Area was refined 

to produce a subregional-scale numerical groundwater-flow 

model capable of simulating flow through alluvial aquifers, 

referred to in this report as the “CPN model.”

The CPN model was used to estimate available 

groundwater resources and the effects of groundwater 

development and prolonged drought (fig. 6). The CPN model 

had a finer grid size than the Central Oklahoma aquifer model 

and included a layer for alluvial deposits. The CPN model 

had drain cells to allow groundwater to discharge to the east 

and had fewer layers representing bedrock aquifers than 

the Central Oklahoma aquifer model, with two layers in the 

Central Oklahoma aquifer and an additional layer representing 

the part of the Wellington Formation that contains saline 

groundwater. The CPN model was calibrated using trial-anderror and automated parameter-estimation techniques.

A higher-resolution numerical groundwater-flow model, 

the inset model (fig. 7), was constructed in the CPN model 

active area for local-scale analysis. The inset model was used 

to determine sustainable use of groundwater resources in two 

economic development zones (EDZs) by using state-of-the-art 

applications, including the Groundwater Management Process 

(Banta and Ahlfeld, 2013). Additional details about estimation 

of hydrogeologic properties, model features, the simulations, 

and model calibration can be found in Ryter and others (2015).

Model calibration was done by comparing the differences 

(residuals) between measurements made in the field and 

simulated measurements made with a model. Figure 7 

shows the distribution of steady-state head residuals for all 

observation wells and the associated model layer for the 

steady-state simulation; figure 8 depicts head residuals for 

the transient simulation. The mean residual for groundwater 

heads in the steady-state model was -1.1 ft, indicating that 

on average, simulated groundwater heads were 1.1 ft higher 

than measured groundwater heads. For transient groundwater 

heads in the Central Oklahoma aquifer, the mean residual was 

-1.7 ft, indicating that on average, simulated groundwater 

heads were 1.7 ft higher than measured groundwater heads. 

The mean residual was -4.1 ft for transient groundwater heads 

in the North Canadian River alluvial aquifer. The maximum 

value of the root-mean-squared groundwater head residuals for 

steady-state and transient simulations of the Central Oklahoma 

aquifer and transient simulation of the North Canadian River 

alluvial aquifer was about 3 percent of the total groundwaterlevel relief (450 ft), indicating that errors or inaccuracies were 

only a minimal part of the total model response (Anderson 

and Woessner, 1992). Figure 8 shows the correlation between 

measured and simulated groundwater-level (head) transient 

simulation observations. Scatter about the regression line was 

caused by local variations in the Central Oklahoma aquifer 

not included in the model, but there was a reasonable general 

correlation with a coefficient of determination (R2) value of 

0.98.

The CPN model provided reasonable matches between 

the simulated base flow composing streamflow and estimated 

base flow composing streamflow at the Harrah streamflowgaging station (fig. 9A) and the Shawnee streamflow-gaging 

station (fig. 9B), shown as streamflow on those figures. The 

mean estimated base flow used in the transient model was 

604 cubic feet per second (ft3/s), and the mean residual for 

transient base flow was 74 ft3/s, indicating that, on average, 

simulated base flow was about 12 percent less than the mean 

estimated base flow. This difference was caused, at least in 

part, by runoff peaks coming into the model from upstream 

and no simulated routing of runoff within the model area. 

The CPN numerical groundwater-flow model only affects the 

streamflow routed through the model by changes in base flow, 

which is a relatively small fraction of streamflow during peakflow periods.
12 Summary of USGS Studies Conducted in Cooperation with the CPN, Central Oklahoma, 2011–14

Lake

Tecumseh

Shawnee

Reservoir 2

North

Fork

Salt

Quapaw

Walnut

Canadian River

Little River

Creek

Creek

Creek

Stanley

Draper

Lake

Horseshoe

Lake

Lake

Thunderbird

Wes Watkins

Reservoir

Shawnee

Reservoir 1

North Canadian River

Shawnee

Norman

Moore

Midwest City

Del City

Oklahoma City

The Village 07241520

07241550

07241800

07230000

07230500

COUNTY

COUNTY

CLEVELAND

COUNTY

SEMINOLE

COUNTY

LINCOLN

COUNTY

POTTAWATOMIE

COUNTY

PONTOTOC

COUNTY

MCCLAIN

OKLAHOMA

97°30' 97°15' 97°00' 96°45'

35°30'

35°15'

35°00'

Base modified from U.S. Geological Survey digital data

Universal Transverse Mercator, zone 14

North American Datum of 1983

EXPLANATION

Alluvial aquifer 

 North Canadian alluvial aquifer (modified from Heran and others, 2003)

 Other alluvial deposits

Central Oklahoma aquifer (Mashburn and others, 2013)

Numerical groundwater-flow model active area boundary

Citizen Potawatomi Nation Tribal Jurisdictional Area boundary

Streamflow-gaging station and number 07230000

0 5 10 15 20 MILES

0 5 10 15 20 KILOMETERS

Area enlarged

OKLAHOMA

Figure 6. Location of the Citizen Potawatomi Nation Tribal Jurisdictional Area, hydrological features, and the Central Oklahoma and 

alluvial aquifers in central Oklahoma (from Ryter and others, 2015).
Groundwater/Surface-Water Simulations 13

COUNTY

COUNTY

CLEVELAND

COUNTY

SEMINOLE

COUNTY

LINCOLN

COUNTY

POTTAWATOMIE

COUNTY

PONTOTOC

COUNTY

MCCLAIN

OKLAHOMA

97°30' 97°15' 97°00' 96°45'

35°30'

35°15'

35°00'

Base modified from U.S. Geological Survey digital data

Universal Transverse Mercator, zone 14

North American Datum of 1983

Inset model

active area,

as shown on

figure 10

Numerical groundwater-flow

 model (CPN model)

 Boundary condition, by cell type

 Drain

 General head boundary

 SFR2 stream cell

 Lake cell

 Top active layer

 Alluvial aquifer

 Central Oklahoma aquifer

Economic development zone

Citizen Potawatomi Nation Tribal 

 Jurisdictional Area boundary

Potentiometric contour—Shows altitude

 at which water level would have stood

 in tightly cased wells, 1986–87. Contour 

 interval 50 feet. Datum is NAVD 88 

 (Mashburn and others, 2013)

2

1

2

2

3

EXPLANATION

SFR2, Streamflow-routing package version 2

900

Pumping well

Observation well with layer number, 

 by steady-state head residual, in feet

 –39.0 to –24.3

 –24.2 to –10.1

 –10.0 to –0.2

 –0.1 to 12.2

 12.3 to 44.7

0 5 10 15 20 MILES

0 5 10 15 20 KILOMETERS

Lake

Thunderbird

2

2

2

2

2

1

1

2

1

1

1

2

2

2

2

3

2

2

2

2

2

2

2

2

4

3 2

3

2

2

2

2

2

2

2

2

2

2

2

2

3

2

2

2

2

2

2

3

1

3

2

2

3 3

2

2 2

2

2

2 3

2

2 3

2

2

2

2

2

2

2

2

2

2

2

2

2

2 2

2

2

2

2

2

2

2

2

2

2

2 2

2

2

2

2

2

2

2

1

2

2

3

2 2

2

2 3

2

2

3

2

2

2

2

2

2

2

3

2

2 2 3

2

3

2 2

2

2

3

2

2 2 2

2 2

2

2

2

2

3 1 2

2

2 2

2

1

2

2

1,050

1,000

1,100

1,100

1,050

1,100

1,050

950

1,000

900

950

1,100

1,100

1,050

1,000

950

1,200

1,150

1,100

1,150

1,050

950

900

1,100

1,000

950

1,000

1,050

Figure 7. Citizen Potawatomi Nation numerical groundwater-flow model active area with the 1986–87 potentiometric surface, steadystate head residuals, locations of model features, and the inset model domain for the Citizen Potawatomi Nation Tribal Jurisdictional 

Area in central Oklahoma (from Ryter and others, 2015).
14 Summary of USGS Studies Conducted in Cooperation with the CPN, Central Oklahoma, 2011–14

Two EDZs along the North Canadian River were 

examined for sustainable groundwater development: the 

geothermal supply area and Iron Horse Industrial Park 

(fig. 10). Both areas are underlain by the North Canadian 

River alluvial aquifer, and the groundwater resources in 

those areas are pumped from that aquifer. The geothermal 

supply area required a continuous flow of 500 gal/min from 

one or more wells located in that area. There was no specific 

pumping rate desired for the Iron Horse Industrial Park—the 

objective of the simulation for that EDZ was to determine the 

amount of groundwater that could be sustainably withdrawn 

at that site. Water quality also was of interest at the Iron Horse 

Industrial Park because stream water in this area contains 

more total dissolved solids and chlorides, nitrogen, and 

organic compounds than the groundwater in these alluvial 

deposits (Becker, 2014); therefore, the volume of stream 

water entering the Iron Horse Industrial Park well field was 

estimated. Groundwater drawdown around the pumping 

wells and effects on streamflow in the North Canadian River 

were evaluated over the entire transient model period of 21 

years; thus, the pumping rates were conservative and were 

less than short-term pumping rates that could be achieved 

by cycling pumping rates from several wells. The principal 

concern at these two EDZs was that head drawdown would 

deplete groundwater in the alluvial aquifer at an unsustainable 

rate. Head constraints were placed on all wells to limit the 

simulated head drawdown. The maximum simulated head 

drawdown at each of the geothermal supply managed wells 

was set at 16.4 ft, which was estimated to be the maximum 

drawdown that would not cause loss of well yield. Head 

constraints for the simulation at the Iron Horse Industrial Park 

well field allowed the head to drop as much as one-half of the 

predevelopment saturated thickness in the North Canadian 

River alluvial aquifer at each well, which was determined to 

be the threshold beyond which well yields would decrease at 

that EDZ.

Optimized pumping rates for the five wells at the 

geothermal supply area ranged from 98 to 201 gal/min, with 

the combined optimized pumping rate being about 638 gal/

min, which exceeded the goal of 500 gal/min pumping for 

those wells. The total pumping rate might be increased by 

increasing well spacing or adding wells outside of the well 

field, or both.

Measured head, in feet

850 900 950 1,000 1,050 1,100 1,150 1,200 1,250

Simulated head, in feet

850

900

950

1,000

1,050

1,100

1,150

1,200

1,250

Simulated head = 0.9833 (measured head) + 19.575

Coefficient of determination (R2

) = 0.98

Linear regression (transient 

 groundwater head)

Transient groundwater head

EXPLANATION

Figure 8. Transient measured groundwater heads and simulated groundwater heads for the Citizen Potawatomi Nation numerical 

groundwater-flow model, central Oklahoma (from Ryter and others, 2015).
Groundwater/Surface-Water Simulations 15

1988198919901991199219931994199519961997199819992000200120022003200420052006200720082009

198819891990

1991

1992199319941995

199619971998

19992000

200120022003

20042005200620072008

2009

Date

10

100

1,000

10,000

10

100

1,000

10,000

100,000

Streamflow, in cubic feet per second

B. North Canadian River at Shawnee, Oklahoma

A. North Canadian River near Harrah, Oklahoma

EXPLANATION

Simulated

Estimated

Figure 9. Simulated and estimated streamflows for North Canadian River streamflow-gaging stations, 1988–2009 (from Ryter and 

others, 2015). A, Near Harrah, Oklahoma. B, At Shawnee, Okla.
16 Summary of USGS Studies Conducted in Cooperation with the CPN, Central Oklahoma, 2011–14

EXPLANATION

Economic development zone

 boundary

Pumping well

Observation well

Numerical groundwater-flow

 model (CPN model)

 Top active layer

 Alluvial aquifer

 Central Oklahoma aquifer

 Boundary condition, by cell type

 General head boundary cell

 SFR2 stream cell

SFR2, Streamflow-routing package version 2

Base modified from U.S. Geological Survey digital data

Universal Transverse Mercator, zone 14

North American Datum of 1983

270

HARDESTY ROAD

E WALNUT STREET

0 0.5 1.0 1.5 2.0 MILES

0 0.5 1.0 1.5 2.0 KILOMETERS

North Canadian River

Iron Horse

Industrial

Park 

Geothermal Geothermal supply area

96°58' 96°57' 96°56' 96°55' 96°54' 96°53' 96°52'

35°21'

35°20'

35°19'

35°18'

35°17'

35°16'

Shawnee

Figure 10. Inset model active area, top active layer, and boundary condition cells and locations of economic development zones 

simulated for sustainable yields, Citizen Potawatomi Nation Tribal Jurisdictional Area, central Oklahoma (from Ryter and others, 2015).
Groundwater/Surface-Water Simulations 17

Optimized pumping rates for the 16 managed wells at 

the Iron Horse Industrial Park ranged from 62 to 141 gal/

min, with the combined estimated optimized pumping rate at 

that EDZ being 1,472 gal/min. Under pumping conditions, 

the base flow to the North Canadian River adjacent to the 

Iron Horse Industrial Park well field was decreased, and the 

groundwater head declined to the point where stream water 

began to infiltrate the alluvial aquifer. Flow into and out of 

each stream reach defined in the inset model was calculated 

by the Streamflow-Routing SFR2 package (Niswonger and 

Prudic, 2005). Rates of induced infiltration of stream water 

to the aquifer at the optimal groundwater-pumping rate at the 

Iron Horse Industrial Park are shown for each stream reach 

numbered upstream to downstream on figure 11. The total rate 

of induced infiltration from the North Canadian River for the 

optimal pumping scheme was 4.3 gal/min, which was about 

0.3 percent of the total pumping rate of 1,472 gal/min.

To estimate the effects of drought on streamflow and 

groundwater storage, the CPN model was altered to simulate 

estimated drought conditions. There have been several severe 

hydrologic droughts in the study area since recordkeeping 

began in 1925, including the Dust Bowl drought (1929–41) 

and the droughts of 1952–56, 1961–72, and 1976–81 

(Shivers and Andrews, 2013). The duration of these drought 

periods ranged from 4 years in the 1950s to the 13-year-long 

Dust Bowl. The period of this study does not include any 

of these historical droughts, so the effects of hypothetical 

drought conditions were estimated on the basis of hydrologic 

characteristics of recorded droughts. The years 1953 and 

2011 had the largest negative departures from long-term 

median precipitation, with nearly 50-percent decreases from 

the median annual precipitation being recorded (Shivers and 

Andrews, 2013). Ryter and others (2015) approximated the 

effects of a sustained, severe drought by decreasing recharge 

over the entire CPN model for each stress period by 50 percent 

from 1990 to 2000. Changes to the volume of groundwater in 

storage in the CPN Tribal Jurisdictional Area were estimated 

by comparing the model run under calibrated recharge 

conditions to the model run with hypothetical drought 

recharge conditions by using the “ZONEBUDGET” program 

(Harbaugh, 1990).

During the hypothetical drought, model recharge to 

the North Canadian River alluvial aquifer decreased by 

441,000 acre-feet (acre-ft) and to the Central Oklahoma 

aquifer by 696,000 acre-ft. This decrease in recharge caused 

a decrease of 361,500 acre-ft of groundwater in storage 

(14,100 acre-ft or 8.6 percent in the North Canadian River 

alluvial aquifer and 347,400 acre-ft or 0.2 percent in the 

Central Oklahoma aquifer) by the end of the simulated 

drought. The total change in groundwater storage was 

approximately 0.2 percent of all groundwater in storage 

beneath the study area by the end of the drought period. 

This volume of groundwater loss showed that the Central 

Oklahoma aquifer is a bedrock aquifer that has relatively 

low rates of recharge from the land surface. Simulated base 

flow to streams in the model during the simulated drought 

decreased by 678,500 acre-ft (33 percent); base flow to 

the North Canadian River decreased by 386,500 acre-ft 

(37 percent); and base flow for all other parts of the CPN 

Tribal Jurisdictional Area decreased by 292,000 acre-ft 

(28 percent). Approximately 11 percent of the decrease 

in recharge to the North Canadian River alluvial aquifer 

and 66 percent of the decrease in recharge to the Central 

Oklahoma aquifer were offset by changes in storage and base 

flow to streams.

The CPN model also was used to simulate changes 

to streamflow in the North Canadian River during and 

after the drought period. Immediately after the start of the 

hypothetical drought, the percent change of the simulated 

base-flow component composing streamflow in the North 

Canadian River at the Shawnee streamflow-gaging station 

decreased because of decreased base flow and later started to 

rise following the relatively wet years of 1993 and 1995 until 

the end of the simulated drought in 2000 (fig. 12). After the 

simulated drought period, the percent change of base-flow 

composing streamflow slowly recovered through 2008 as 

recharge restored the amount of groundwater in storage. The 

largest estimated decrease in mean streamflow was 28 percent 

during September of 1994. Streamflow did not recover to nearnormal streamflow conditions until the wet year of 2007–7 

years after the end of the hypothetical drought. The delay in 

streamflow recovery was caused by gradual aquifer recharge 

replenishing groundwater storage that had been depleted 

during the drought.
18 Summary of USGS Studies Conducted in Cooperation with the CPN, Central Oklahoma, 2011–14

Iron Horse Industrial Park

96°53'45" 96°53'30" 96°53'15" 96°53'00" 96°52'45"

35°19'15"

35°19'00"

35°18'45"

35°18'30"

IHW06

IHW05

IHW10

IHW04

IHW02

IHW03

IHW01

IHW09

IHW16

IHW07 IHW08

IHW11 IHW13 IHW14

IHW12

IHW15

110

99

79

73

109

136

62

73

71 81

103 100 82

141

78

75

17

33

27

49

43

29

24

35

19 20

23

48

44

18

40

46

41

31

34

8

21

32

39 38

30

37

28

10

13

45

11

47

14

25 26

16 15

12

22

9

42

36

Note: Total estimated rate of optimized pumping was 1,472 gallons per minute.

 Total rate of induced infiltration from the North Canadian River for optimal 

 pumping scheme was 4.3 gallons per minute (0.3 percent of pumping).

Base modified from U.S. Geological Survey digital data

Universal Transverse Mercator, zone 14

North American Datum of 1983

0 400 FEET

0 100 200

200

300 400 METERS

EXPLANATION

Economic development zone—Iron Horse Industrial Park

 (location shown on fig. 10)

Numerical groundwater-flow model cell for managed well

 at the Iron Horse Industrial Park, by optimized pumping 

 rate, in gallons per minute—Well number and pumping 

 rate are shown next to cell

 62

 63 to 75

 76 to 82

 83 to 110

 111 to 141

Stream reach and stream reach number, by induced infiltration from North

 Canadian River for optimal pumping scheme, in cubic feet per second 

0 to 0.006

0.007 to 0.014

0.015 to 0.021

0.022 to 0.032

0.033 to 0.048

40

22

15

8

25

Figure 11. Groundwater Management Process managed wells, optimized pumping rates, and resulting effects on induced infiltration 

by stream reach number at the Iron Horse Industrial Park, Citizen Potawatomi Nation Tribal Jurisdictional Area, central Oklahoma (from 

Ryter and others, 2015).
Summary 19

Summary

The U.S. Geological Survey conducted hydrologic 

studies and published three U.S. Geological Survey scientific 

investigations reports in cooperation with the Citizen 

Potawatomi Nation (CPN) from 2011 to 2014 to characterize 

the quality and quantity of water resources. The study 

area consists of approximately 960 square miles in parts 

of three counties in central Oklahoma. This study area has 

an abundance of water resources, being underlain by three 

principal aquifers (alluvial/terrace, Central Oklahoma, and 

Vamoosa-Ada), bordered by two major rivers (North Canadian 

and Canadian), and having several smaller drainages. The 

Central Oklahoma aquifer (also referred to as the “GarberWellington aquifer”) underlies approximately 3,000 square 

miles in central Oklahoma in parts of Cleveland, Logan, 

Lincoln, Oklahoma, and Pottawatomie Counties and much 

of the study area. Water from these aquifers is used for 

municipal, industrial, commercial, agricultural, and domestic 

supplies.

Much of the water in the area was of good quality, 

though some parts of this study area had water quality 

impaired by very hard surface water and groundwater, 

large chloride concentrations in some smaller streams, 

relatively large concentrations of nutrients and counts of 

fecal-indicator bacteria in the North Canadian River, and 

uranium concentrations that exceeded the U.S. Environmental 

Protection Agency (EPA) Maximum Contaminant Level 

standard in water samples collected from a small number 

of wells. Most stream-water samples collected from the 

Little River by the U.S. Geological Survey in 2012–13 had 

dissolved solids concentrations exceeding the EPA Secondary 

Maximum Contaminant Level for public water supplies of 

500 milligrams per liter. Concentrations of nitrogen and 

phosphorus compounds were substantially larger in the North 

Canadian River than in the Little River or Deer Creek. Most 

trace-element concentrations in streams were less than EPA 

Maximum Contaminant Levels set for public water supplies. 

Larger numbers of organic compounds were measured in 

water samples collected from the North Canadian River than 

from the Little River or Deer Creek. 

Date

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Streamflow, in cubic feet per second

0

500

4,000

3,500

2,500

3,000

2,000

1,500

1,000

Percent change in streamflow

–60

–50

–40

–30

–20

–10

0

Drought begins

Drought ends

EXPLANATION

Streamflow during drought

Percent change

Normal streamflow

Percent change 50-month moving average

North Canadian River at Shawnee, Oklahoma

Figure 12. Normal streamflow and streamflow during a simulated drought from 1990 to 2000 at the North Canadian River at Shawnee, 

Oklahoma, streamflow-gaging station, with percent change during and after the simulated drought (from Ryter and others, 2015).
20 Summary of USGS Studies Conducted in Cooperation with the CPN, Central Oklahoma, 2011–14

A numerical groundwater-flow model was constructed 

by using hydrogeologic information from the part of the 

Central Oklahoma aquifer model that covered the CPN Tribal 

Jurisdictional Area. The new model, termed the CPN model, 

estimated available groundwater resources and the effects of 

groundwater development and prolonged drought. The CPN 

model had a finer grid size than the Central Oklahoma aquifer 

model and included a layer to represent alluvial deposits. The 

CPN model had drain cells to allow groundwater to discharge 

to the east and had fewer layers representing bedrock aquifers 

than the Central Oklahoma aquifer model, with two layers 

in the Central Oklahoma aquifer and an additional layer 

representing the part of the Wellington Formation that contains 

saline groundwater. The CPN model was calibrated using trialand-error and automated parameter-estimation techniques. 

To optimize the use of water resources at two economic 

development zones (EDZs) just south of the city of Shawnee, 

Okla., the U.S. Geological Survey Groundwater Management 

Process for MODFLOW was used with an inset model 

constructed from a part of the CPN model. Groundwater 

withdrawal amounts were optimized by using the Groundwater 

Management Process at the geothermal supply area and the 

Iron Horse Industrial Park. The target combined pumping rate 

for all wells at the geothermal supply area was 500 gallons 

per minute (gal/min). The Iron Horse Industrial Park required 

an estimate of the maximum groundwater development and 

the amount of North Canadian River water that may enter the 

wells. There were 5 managed wells used at the geothermal 

supply area and 16 managed wells used at the Iron Horse 

Industrial Park. The five managed wells at the geothermal 

supply area produced a maximum combined simulated flow of 

638 gal/min of continuous pumping, which exceeded the 500-

gal/min goal. At the Iron Horse Industrial Park, 16 wells had a 

combined sustainable pumping rate of 1,472 gal/min, and only 

4.3 gal/min (0.3 percent) of the pumped water was estimated 

to come from induced infiltration from the North Canadian 

River.

The effects of a hypothetical 10-year drought on 

groundwater in the CPN Tribal Jurisdictional Area and 

streamflow at the Shawnee, Okla., streamflow-gaging station 

were estimated by using the CPN model. The drought was 

assumed to reduce precipitation and, in turn, recharge by 50 

percent for the period 1990–2000. The decrease in recharge 

during the hypothetical drought caused groundwater in 

storage over the entire model to decrease by 361,500 acre-feet 

(acre-ft) (14,100 acre-ft or 8.6 percent in the North Canadian 

River alluvial aquifer and 347,400 acre-ft or 0.2 percent in 

the Central Oklahoma aquifer), or approximately 0.2 percent 

of all groundwater in storage at the end of the drought period. 

This volume of groundwater loss showed that the Central 

Oklahoma aquifer is a bedrock aquifer that has relatively low 

rates of recharge from the land surface. The budget for base 

flow to the North Canadian River estimated that the change 

in groundwater flow to the North Canadian River decreased 

during the 10-year drought by 386,500 acre-ft (37 percent). 

In all other parts of the CPN Tribal Jurisdictional Area, base 

flow composing streamflow decreased by 292,000 acre-ft 

(28 percent). The total change in base flow composing 

streamflow in the model was a decrease of 678,500 acre-ft 

(33 percent). Simulated streamflow returned to normal rates 

approximately 7 years after the end of the hypothetical 

drought.

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