U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2010–5227

In cooperation with Greene County, Missouri, the U.S. Army Corps of Engineers, and 

the Missouri Department of Natural Resources

Groundwater-Flow Model and Effects of Projected 

Groundwater Use in the Ozark Plateaus Aquifer System in 

the Vicinity of Greene County, Missouri—1907-2030

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek

Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River

Stockton

Lake

Fellows

Lake McDaniel Lake

Lake Springfield

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Approximate area of unsaturated

Ozark Aquifer induced by 

groundwater withdrawal

1,200

1,100

800

1,400

1,300

1,200

800

1,100

900

900

900

1,000

1,200

1,100

1,300

1,000

1,000

1,100

Base from U.S. Geological Survey digital data, 1:100,000, 1995

and U.S. Census TIGER/line files, 2003

Universal Transverse Mercator projection, zone 15 Potentiometric surface data from

Richards and Mugel, 2008

Geologic data modified from Missouri 

Department of Natural Resources, 2007

93°30' 93°00'

37°30'

37°00'

0 10 20 MILES

0 10 20 KILOMETERS

CHESAPEAKE FAULT

BATTLEFIELD-SAC 

RIVER FAULT

GRAYDON SPRINGS FAULT

Groundwater-Flow Model and Effects of 

Projected Groundwater Use in the Ozark 

Plateaus Aquifer System in the Vicinity of 

Greene County, Missouri—1907-2030

By Joseph M. Richards

In cooperation with Greene County, Missouri, the U.S. Army Corps of Engineers, 

and the Missouri Department of Natural Resources

Scientific Investigations Report 2010–5227

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2010

Suggested citation:

Richards, Joseph M., 2010, Groundwater-flow model and effects of projected groundwater use in the Ozark 

Plateaus Aquifer System in the vicinity of Greene County, Missouri - 1907-2030: U.S. Geological Survey Scientific 

Investigations Report 2010-5227, 106 p.

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

To learn about the USGS and its information products visit http://www.usgs.gov/

1-888-ASK-USGS

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.
iii

Acknowledgments

Measurement of water levels, compilation of well construction data, and creation of the 2006 

Ozark aquifer potentiometric-surface map were facilitated by Doug Mugel (USGS). Compilation of groundwater-use data was facilitated by William Otero (USGS) and Tim Smith (Greene 

County). Jim Vandike (Missouri DNR) provided input on aquifer properties, conceptual groundwater flow, and the general hydrology of the hydrogeologic units in the model area. Many individuals from local municipalities, industries, and private water suppliers provided groundwateruse data and water-level data to support this modeling effort. The cooperation of well owners 

who allowed access to their wells for water-level measurements was greatly appreciated. 
iv

Contents

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

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

Purpose and Scope ..............................................................................................................................5

Previous Investigations........................................................................................................................5

Approach................................................................................................................................................7

Description of Model Area..................................................................................................................7

Hydrogeologic Setting of the Ozark Plateaus Aquifer System...............................................................8

Springfield Plateau Aquifer...............................................................................................................14

Ozark Confining Unit...........................................................................................................................14

Ozark Aquifer.......................................................................................................................................14

St. Francois Confining Unit................................................................................................................20

Conceptual Model of the Groundwater-Flow System ...........................................................................20

Description of the Groundwater-Flow Model .........................................................................................24

Groundwater-Modeling Software....................................................................................................24

Simplifying Assumptions....................................................................................................................24

Model Specifications .........................................................................................................................25

Finite-Difference Grid................................................................................................................25

Initial Hydrogeologic Unit Discretization ......................................................................25

Final Hydrogeologic Unit Discretization........................................................................25

Hydraulic Property Computation....................................................................................27

Stress Period Discretization ....................................................................................................27

Model Boundary Conditions ....................................................................................................27

Areally Distributed Recharge .........................................................................................27

Rivers ................................................................................................................................33

Springs................................................................................................................................40

General-Head Boundaries ..............................................................................................40

Lateral Flow at the Model Boundary ....................................................................40

Vertical Flow Through the Bottom of the Ozark Aquifer....................................40

Lakes .......................................................................................................................45

Groundwater Use.......................................................................................................................45

Model Calibration.........................................................................................................................................47

Hydraulic Property Estimation..........................................................................................................47

Horizontal Hydraulic Conductivity...........................................................................................47

Vertical Hydraulic Conductivity ...............................................................................................53

Specific Storage ........................................................................................................................61

Specific Yield..............................................................................................................................61

Calibrated Hydraulic Properties Compared To Previously Published Values..................61

Springfield Plateau Aquifer Calibrated Hydraulic Properties ...................................61

Ozark Confining Unit Calibrated Hydraulic Properties ...............................................61

Ozark Aquifer Calibrated Hydraulic Properties ...........................................................61

Water-Level Observations.................................................................................................................62

Streamflow Observations..................................................................................................................79

Spring-Flow Observations.................................................................................................................79
v

Water Budget ......................................................................................................................................79

Sensitivity Analysis.............................................................................................................................82

Effects of Projected Groundwater Use ....................................................................................................88

Projected Groundwater Use .............................................................................................................88

Continued Pumpage at the 2006 Rate..............................................................................................92

Drought Effects and Low Population Growth.................................................................................93

Drought Effects and High Population Growth................................................................................93

Low and High Population Growth with New Industrial Wells .....................................................93

Model Limitations.........................................................................................................................................99

Summary and Conclusions.......................................................................................................................103

References Cited........................................................................................................................................105

Figures

1–5 Maps showing—

 1. Location of current and previous model areas.................................................................3

 2. Location of communities in study area, which corresponds

 to the model area for the model described in this report................................................4

 3. Potentiometric surface of the Ozark aquifer 2006-07

 and outcrop areas of the hydrogeologic units in the study area...................................6

 4. Altitude of the land surface in the model area..................................................................9

 5. Distribution of karst features at the land surface in the model area. .........................10

6. Northwest to southeast cross section from A to A’ (on figure 3)

of the hydrogeologic units in the model area with model layers indicated.......................11

7. Southwest to northeast cross-section from B to B’ (on figure 3)

 of the hydrogeologic units in the model area with model layers indicated.......................12

8–14 Maps showing—

 8. Distribution of the hydrogeologic units at the upper surface

 of the cells in layer 1 and water-level observations used for

 calibration in the model. .....................................................................................................15

 9. Thickness of the Springfield Plateau aquifer in the study area. ..................................16

 10. Configuration of the top of the Ozark confining unit in the study area. ......................18

 11. Thickness of the Ozark confining unit in the study area. ..............................................19

 12. Configuration of the top of the Ozark aquifer in the study area. ..................................21

 13. Thickness of the Ozark aquifer in the study area. ..........................................................22

 14. Configuration of the top of the St. Francois confining unit

 in the study area...................................................................................................................23

15. Conceptual cross section of model layers compared with

 the hydrogeologic units..............................................................................................................26

16. Map showing distribution of hydrogeologic units in layer 1 of the model.........................28

17. Map showing distribution of hydrogeologic units in layer 2 of the model.........................29

18. Hydrograph of the Longview monitoring well in McDonald County, Missouri..................31

19–31 Maps showing—

 19. Areally distributed recharge zones...................................................................................32

 20. Land use/land cover distribution in the model area.......................................................36
vi

 21. River and spring observation points specified in the model.........................................37

 22. Streambed conductance values for rivers specified in the

 model and location of lake general-head boundary cells.............................................38

 23. Discharge measurement locations for the seepage run

 in the James River Basin, 2006, discharge measurement

 locations from Imes (1989), and locations of selected

 wastewater-treatment outfalls..........................................................................................39

 24. Vertical general-head boundary conductance values

 for model layer 3 simulating flow through the bottom

 of the Ozark aquifer..............................................................................................................44

 25. Pumping wells specified in the model area.....................................................................46

 26. Groundwater use from wells in the Ozark aquifer

 in 2006 (domestic-supply wells omitted for clarity)........................................................52

 27. Horizontal hydraulic conductivity in the Ozark aquifer

 estimated from specific-capacity data of wells. ............................................................54

 28. Horizontal and vertical hydraulic conductivity,

 specific storage, and specific yield zones for the

 Springfield Plateau aquifer used in the model to calculate

 composite hydraulic properties.........................................................................................58

 29. Horizontal and vertical hydraulic conductivity, specific storage,

 and specific yield zones for the Ozark confining unit used

 in the model to calculate composite hydraulic properties. ..........................................59

 30. Horizontal and vertical hydraulic conductivity, specific storage,

 and specific yield zones for the Ozark aquifer used in the model

 to calculate composite hydraulic properties. .................................................................60

 31. Potentiometric surface of the Springfield Plateau aquifer, 2006. ................................64

32. Graph showing daily water-level altitude of the Ozark aquifer

at the Marshfield monitoring well from January 1, 2006,

to December 31, 2009. .................................................................................................................65

33–36 Maps showing—

 33. Simulated head in layer 3 and the difference between

 simulated head and observed water-level altitudes

 at observation points, 1987.................................................................................................67

 34. Simulated head in layer 3 and the difference between

 simulated head and observed water-level altitudes

 at observation points, 1993.................................................................................................68

 35. Simulated head in layer 3 and the difference between

 simulated head and observed water-level altitudes

 at observation points, 1996.................................................................................................69

 36. Simulated head in layer 3 and the difference between

 simulated head and observed water-level altitudes

 at observation points, 2006.................................................................................................70

37. Graph showing relation between simulated head and observed

water-level altitudes for selected measurements for layer 3

in the model. .................................................................................................................................71

38. Graph showing difference between simulated head and

observed water-level altitudes (observed minus simulated)

for selected measurements for layer 3 in the model.............................................................72
vii

39. Map showing simulated head in layer 1 and the difference between

simulated head and observed water-level altitudes at

observation points, 1989. ............................................................................................................73

40. Map showing simulated head in layer 1 and the difference between

simulated head and observed water-level altitudes at

observation points, 2006. ............................................................................................................74

41. Graph showing relation between simulated head and observed

water-level altitudes for selected measurements for layer 1 in the model. ......................75

42. Graph showing difference between simulated head and observed

water-level altitudes (observed minus simulated) for selected

measurements for layer 1 in the model....................................................................................76

43. Graph showing relation between simulated head and observed

water-level altitudes for all measurements made from 1987 to 2006

for layer 1 and layer 3 in the model...........................................................................................77

44. Graph showing difference between simulated head and observed

water-level altitudes (observed minus simulated) for all measurements

made from 1987 to 2006 for layer 1 and layer 3 in the model................................................78

45. Map showing simulated head change in layer 1 and layer 3

following a 10-percent increase in horizontal hydraulic conductivity

in zone 1 of the Ozark aquifer (OZHK1, table 13; OZA1, fig. 30)

computed at the end of the calibration period in 2006..........................................................86

46. Map showing simulated head change in layer 1 and layer 3

following a 10-percent increase in recharge in areal recharge zone 1

(RCHZ1, table 13; RCH1, fig. 19) computed at the end of the calibration

period in 2006................................................................................................................................87

47. Map showing simulated head change in layer 1 and layer 3

following a 10-percent increase in horizontal hydraulic conductivity

in zone 1 of the Ozark aquifer (OZHK1, table 13; OZA1, fig. 30)

computed at the end of the prediction period in 2030 for scenario 7 .................................89

48. Graph showing estimated high growth population change

from 2006 to 2030 for selected communities in the model area

(Greene County Resource Management Department,

written commun., 2008)...............................................................................................................92

49–56 Maps showing—

 49. Simulated head at the end of 2030 in layer 3 and difference

 in simulated head between 2006 and 2030 (2006 minus 2030)

 for hypothetical scenario 1—groundwater use fixed at 2006 rate..............................94

 50. Simulated head at the end of 2030 in layer 3 and difference

 in simulated head between 2006 and 2030 (2006 minus 2030)

 for hypothetical scenario 2—low groundwater-use growth rate

 and 4-year drought from 2010 to 2013...............................................................................95

 51. Simulated head at the end of 2030 in layer 3 and difference

 in simulated head between 2006 and 2030 (2006 minus 2030)

 for hypothetical scenario 3—low groundwater-use growth rate

 and 4-year drought from 2027 to 2030...............................................................................96

 52. Simulated head at the end of 2030 in layer 3 and difference

 in simulated head between 2006 and 2030 (2006 minus 2030)

 for hypothetical scenario 4—high groundwater-use growth rate

 and 4-year drought from 2010 to 2013...............................................................................97
viii

 53. Simulated head at the end of 2030 in layer 3 and difference

 in simulated head between 2006 and 2030 (2006 minus 2030)

 for hypothetical scenario 5—high groundwater-use growth rate

 and 4-year drought from 2027 to 2030...............................................................................98

 54. Simulated head at the end of 2030 in layer 3 and difference

 in simulated head between 2006 and 2030 (2006 minus 2030)

 for hypothetical scenario 6—low groundwater-use growth rate

 and two new industrial wells. ..........................................................................................100

 55. Simulated head at the end of 2030 in layer 3 and difference

 in simulated head between 2006 and 2030 (2006 minus 2030)

 for hypothetical scenario 7—high groundwater-use growth rate

 and two new industrial wells. ..........................................................................................101

 56. Difference in simulated head in 2030 between

 scenario 3 and scenario 6. ...............................................................................................102

Tables

1. Correlation of hydrogeologic units and stratigraphic units

in the model area (modified from Imes, 1989).........................................................................13

2. Reported hydraulic property values for the model area and vicinity..................................17

3. Estimated recharge values of the Springfield Plateau aquifer

computed from continuous water-level data collected at

the Longview monitoring well in McDonald County, Missouri. ...........................................30

4. Areally distributed recharge zones and values......................................................................33

5. Annual precipitation totals observed and total model recharge

specified in the model area, 1907 - 2008..................................................................................34

6. Estimated 7-day annual low-flow discharge values for

the 2-year recurrence interval at selected sites....................................................................41

7. Base-flow discharge estimates of selected springs.............................................................42

8. Lakes specified in layer 1 of the model....................................................................................45

9. Stress period length, pumping rates, and number of water-level

observations used in the model. ...............................................................................................48

10. Hydraulic property values specified in the calibrated model. .............................................53

11. Hydraulic conductivity estimated from specific-capacity data

for selected wells in the model area........................................................................................55

12. Flow budget for the three layers of the model at the end of

the initial steady-state stress period, the 101st stress period (2006),

and the 125th stress period (2030) for hypothetical scenario 7.............................................80

13. Sensitivity of model to changes in parameter values............................................................83

14. Hypothetical pumping scenarios 2007 to 2030........................................................................90

15. Projected population growth per year (in percent of 2006 population)

and number of wells in 2006 per percentage range

of total operating capacity. ........................................................................................................91
ix

Conversion Factors and Datums

Multiply By To obtain

Length

inch 2.54 centimeter (cm)

inch 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square foot (ft2) 0.09290 square meter (m2)

square mile (mi2) 2.590 square kilometer (km2) 

Volume

cubic foot (ft3) 0.02832 cubic meter (m3) 

Flow rate

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

cubic foot per day (ft3/d) 0.02832 cubic meter per day (m3/d)

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

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

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

Hydraulic conductivity

foot per day (ft/d) 0.3048 meter per day (m/d)

Transmissivity

foot squared per day (ft2/d) 0.09290 meter squared per day (m2/d) 

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 

(NGVD 29).
x
Groundwater-Flow Model and Effects of Projected 

Groundwater Use in the Ozark Plateaus Aquifer System 

in the Vicinity of Greene County, Missouri—1907–2030

By Joseph M. Richards

Abstract

Recent and historical periods of rapid growth have 

increased the stress on the groundwater resources in the 

Ozark aquifer in the Greene County, Missouri area. Historical 

pumpage from the Ozark aquifer has caused a cone of 

depression beneath Springfield, Missouri. In an effort to 

ease its dependence on groundwater for supply, the city 

of Springfield built a pipeline in 1996 to bring water from 

Stockton Lake to the city. Rapid population growth in the 

area coupled with the expanding cone of depression raised 

concern about the sustainability of groundwater as a resource 

for future use. A groundwater-flow model was developed 

by the U.S. Geological Survey in cooperation with Greene 

County, Missouri, the U. S. Army Corps of Engineers, and 

the Missouri Department of Natural Resources to assess 

the effect that increased groundwater demand is having on 

the long-term availability of groundwater in and around 

Greene County, Missouri. 

Three hydrogeologic units were represented in the 

groundwater-flow model: the Springfield Plateau aquifer, the 

Ozark confining unit, and the Ozark aquifer. The Springfield 

Plateau aquifer is less than 350 feet thick in the model 

area and generally is a low yield aquifer suitable only for 

domestic use. The Ozark aquifer is composed of a more than 

900-foot thick sequence of dolomite and sandstone in the 

model area and is the primary aquifer throughout most of 

southern Missouri. Wells open to the entire thickness of the 

Ozark aquifer typically yield 1,000 gallons per minute or 

more. Between the two aquifers is the Ozark confining unit 

composed of as much as 98 feet of shale and limestone. Karst 

features such as sinkholes, springs, caves, and losing streams 

are present in both aquifers, but the majority of these features 

occur in the Springfield Plateau aquifer. The solution-enlarged 

fracture and bedding plane conduits in the karst system, 

particularly in the Springfield Plateau aquifer, are capable of 

moving large quantities of groundwater through the aquifer in 

relatively short periods of time. 

Pumpage rates in the model area increased from 

1,093,268 cubic feet per day in 1962 to 2,693,423 cubic feet 

per day in 1987 to 4,330,177 cubic feet per day in 2006. 

Annual precipitation ranged from 25.21 inches in 1953 to 

62.45 inches in 1927 from 1915 to 2006 in the model area. 

Recharge to the model was calculated as 2.53 percent of the 

annual precipitation and was varied annually. Recharge was 

distributed over the model area based on land slope and was 

adjusted in the city limits of Springfield to account for the 

impervious surface. 

A groundwater model with annual stress periods from 

1907 to 2030 was developed using a transient calibration 

period from 1987 to 2006 and a prediction period from 2007 

to 2030 to simulate flow in the Springfield Plateau aquifer 

and the Ozark aquifer. For the model area of approximately 

2,870 square miles, the model hydrogeologic units and 

hydraulic properties were discretized into 253 rows, 

316 columns, and 3 layers with the layer boundaries crossing 

hydrogeologic unit boundaries in some areas. The horizontal 

cell spacing was 1,000 feet by 1,000 feet. The model was 

calibrated by minimizing the difference between simulated 

head and observed water levels and simulated and observed 

flows in rivers and springs. 

Population and the associated groundwater use were 

estimated for 12 communities and the unincorporated area 

of Greene County based on past growth. Each was analyzed 

individually, and a low and high annual rate of growth relative 

to the 2006 population was computed for each community or 

group. Low growth rates ranged from 0.215 percent per year 

in Springfield to 6.997 percent per year in Rogersville. Total 

growth from 2006 to 2030 at the low growth rate ranged from 

5.2 percent in Springfield to 167.9 percent in Rogersville. 

High growth rates ranged from 0.236 percent per year in 

Springfield to 7.345 percent per year in Rogersville. Total 

growth from 2006 to 2030 at the high growth rate ranged from 

5.7 percent in Springfield to 176.3 percent in Rogersville. 

Response of the flow system to selected hypothetical 

pumping stresses and recharge conditions was simulated 
2 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

using the calibrated model. Seven hypothetical scenarios were 

simulated from 2007 to 2030 to test the effects of various 

stresses on the head in the Ozark aquifer. Hypothetical 

scenario 1 continued the 2006 pumping rates without change 

to the end of 2030. Scenario 2 assumed a low population 

growth rate with a 4-year drought at the beginning of the 

prediction period. Scenario 3 assumed a low population 

growth rate with a 4-year drought at the end of the prediction 

period. Scenario 4 assumed a high population growth rate with 

a 4-year drought at the beginning of the prediction period. 

Scenario 5 assumed a high population growth rate with a 

4-year drought at the end of the prediction period. Scenario 

6 and 7 had one new industrial well installed within the city 

limits of Springfield and one new industrial well installed 

about 3.5 miles east of Rogersville. Scenario 6 assumed a 

low population growth rate and scenario 7 assumed a high 

population growth rate. 

Results were compared by examining differences 

in head at the end of the simulation period. All scenarios 

examined resulted in potentiometric-surface declines from 

2006 levels. Results from scenario 1 indicated that even with 

no increase in pumping, the potentiometric surface in the 

Springfield area continued to decline. The maximum decline 

of approximately 62 feet from the 2006 potentiometric surface 

occurred in Springfield. The maximum decline from the 2006 

potentiometric surface in scenarios 2 and 3 was approximately 

203 feet and in scenarios 4 and 5 was approximately 207 feet. 

The drought occurring at the end of the simulation period 

tended to broaden the drawdown area relative to the drought at 

the beginning. Drought timing did not substantially affect the 

potentiometric surface in the Ozark aquifer except for where 

the Ozark aquifer was exposed. Although not a substantial 

difference, the high population growth rate scenarios tended 

to have larger declines than the low population growth rate 

scenarios. As in the previous scenarios, little difference was 

noted between the low and high growth rate in scenario 

6 and 7. Scenarios 6 and 7 showed declines of more than 

640 feet from the 2006 potentiometric surface at the new 

well located in Springfield. The drawdown at the new wells 

decreased relatively quickly with increased distance from the 

well. Simulated head in the nearby cities of Nixa, Ozark, and 

Republic was nearly the same for scenarios 2 through 7 and 

was lower than the head predicted for scenario 1. Results from 

scenarios 2 through 7 indicate that the potentiometric surface 

in 2030 near these cities could decline 100 feet or more from 

the 2006 levels. Because model layers 2 and 3, representing 

the Ozark confining unit and most of the thickness of the 

Ozark aquifer, were simulated as confined, drawdown in the 

wells in the area of the Ozark aquifer that is unconfined or 

becomes unconfined during the simulation period will likely 

be under predicted.

Introduction

The demand for commercial, industrial, and residential 

water from the Ozark aquifer in Greene County, Missouri 

(fig. 1) and the surrounding area has increased steadily since 

the first deep wells were drilled for drinking water as early as 

1907. Springfield (fig. 2), the third largest city in Missouri, 

was incorporated in 1838 (City Utilities of Springfield, 2009) 

and had an estimated 2007 population of 154,770 (Greene 

County Resource Management Department, written commun., 

2009). Greene County had an estimated 2007 population of 

263,793 (Greene County Resource Management Department, 

written commun., 2009). Historical population growth in 

Springfield and surrounding communities has increased 

local demand on the aquifer. The population of Springfield 

nearly doubled between 1950 and 1980, with the majority 

of growth occurring from 1950 to 1970 (Imes, 1989). The 

population of Springfield increased approximately 11 percent, 

from 1970 to 1980 (Imes, 1989). Population growth from 

1970 to 1980 in some surrounding communities exceeded 

24 percent (Imes, 1989). By the 1970s, groundwater pumpage 

from the Ozark aquifer in the Springfield area caused a cone 

of depression in the potentiometric surface (Emmett and 

others, 1978), which continued to grow during the 1980s 

(Imes, 1989). Projected rapid population growth coupled 

with a growing cone of depression in the Ozark aquifer, and 

the fact that the existing surface-water supply was operating 

near its maximum capacity, led Springfield water managers 

to look for alternative sources to supply their water needs. In 

the late 1980s, the city of Springfield began the process of 

supplementing their water supply with water from Stockton 

Lake (fig. 2). The project, completed in 1996, consisted of 

building a pump station and a 30-mile pipeline from Stockton 

Lake to Fellows Lake located 5 miles north of Springfield 

(Burns and McDonald, 2009). 

The population of Springfield had increased by about 

16 percent from 1980 to 2007, whereas Dintelmann and others 

(2006) reported that from 1990 to 2000, population growth 

in the nearby cities of Nixa, Ozark, and Republic (fig. 2) 

was 158 percent, 128 percent, and 34 percent, respectively. 

Commercial, industrial, and residential water use in these 

cities has continued to increase in proportion to the population 

growth, and between 1990 and 2003, these cities increased 

their groundwater pumpage by an estimated 139 percent over 

that same period (Dintelmann and others, 2006). Even though 

Springfield has reduced its dependence on groundwater after 

building the pipeline to Stockton Lake, all other municipal, 

industrial, and residential use in the area is entirely dependent 

on groundwater (Dintelmann and others, 2006). Groundwater 

level measurements made in 2006 and 2007 indicated that the 
Introduction 3Figure 1. Location of current and previous model areas.

Springfield

Finley Creek

Sac River

James River

Turnback Creek

Beaver Creek

Bull Creek

Little Beaver Creek

Niangua River

Osage Fork Gasconade River

Little Sac River

James River

Pomme de

Terre River

Stockton

Lake

Fellows

Lake McDaniel Lake

Lake

Springfield

Table Rock

Lake

D

O

U

GLAS

BA

R

RY

LA

W

RENCE

D

A

DE

CED

A

R

POLK

GREENE

CH

RISTIA

N

STO

NE

TA

NEY

OZA

R

K

D

ALLAS LACLEDE

WEBSTER

WRIG

HT

MODEL AREA (this report; fig. 2)

IMES (1989) MODEL AREA

07052250

07052345

06918440

07053810

07054080

06918460

06918740

06921070 06923250

06927800

07050700

07052500

MCDONALD

COUNTY

LONGVIEW

MONITORING WELL ST. FRANCOIS 

AQUIFER

MONITORING WELL

OREGON

COUNTY

MAP AREA

OZARK PLATEAUS

AQUIFER SYSTEM

MISSOURI

92°30' 93°00' 93°30'

37°30'37°00'

06927800 Streamgage 

 and station number (table 6)

EXPLANATION

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

0 10 20 MILES0 10 20 KILOMETERS
4 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 2. Location of communities in study area, which corresponds to the model area for the model described in this report.

Springfield

Ozark

Nixa

Willard

Aurora

Republic

Marshfield

Brookline

Highlandville

Fair Grove

Seymour

Strafford

Crane

Conway

Battlefield

Sparta Marionville

Ash Grove

Dadeville

Billings

Rogersville

Diggins

Clever

Fordland

Spokane

Pleasant Hope

Hurley

Niangua

Everton

Fremont Hills

Walnut Grove

Morrisville

Mount Vernon

Halltown

Verona

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River

Fulbright Spring

Marshfield 

monitoring well

Stockton

Lake

Fellows

Lake McDaniel Lake

Lake

Springfield

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

39

60

160

44

13

14

13

65 44

14

65

60
Introduction 5

cone of depression identified in the Ozark aquifer in the 

1970s and 1980s continued to expand and deepen 

(Richards and Mugel, 2008). 

The increasing stress on the Ozark aquifer and its 

continuing potentiometric-surface decline has raised new 

concerns about the future groundwater availability and the 

sustainability of current (2006) groundwater use. To assess the 

effect that increased groundwater demand might have on the 

long-term availability of groundwater in Greene County and 

the surrounding area, the U.S. Geological Survey (USGS), 

in cooperation with Greene County, the U.S. Army Corps of 

Engineers, and the Missouri Department of Natural Resources, 

developed and applied a groundwater-flow model to a model 

area covering a part of the Ozark Plateaus aquifer system 

(figs. 1 and 2).

Purpose and Scope 

The purpose of this report is to document a groundwaterflow model that characterizes groundwater flow within a 

part of the Ozark Plateaus aquifer system in the vicinity of 

Greene County, Missouri. A description is presented of the 

development and calibration of the groundwater-flow model 

used to simulate groundwater flow within the Springfield 

Plateau and Ozark aquifers and followed by a description 

of the simulated effects of hypothetical pumping scenarios 

using the calibrated model. The scope of the model is limited 

to the part of the Springfield Plateau aquifer and Ozark 

aquifer within a 2,870 square mile (mi2) area centered on 

Springfield, Missouri.

Previous Investigations

Numerous investigations have been made of the geology, 

hydrology, and water resources in the model area with 

particular emphasis on the city of Springfield and Greene 

County. Because of rapid growth and water-supply concerns, 

Emmett and others (1978) made a comprehensive assessment 

of the water resources and geology of the Springfield 

area, and identified and mapped a cone of depression in 

the potentiometric surface of the Ozark aquifer. By 1974, 

a potentiometric-surface decline from predevelopment 

conditions of nearly 300 feet (ft) in the center of the cone of 

depression was indicated (Emmett and others, 1978). Mapping 

historical water-level data at 10-year intervals, Steinkamp 

(1987) concluded that the cone of depression was present 

beneath Springfield in the late 1930s and that it continued to 

develop over time. In the late 1980s, the USGS completed 

a hydrologic study for the city of Springfield, Missouri. The 

study included the collection of groundwater-use data, the 

collection of historical and current water-level data, and the 

preparation of a groundwater-flow model (Imes, 1989). Imes 

(1989) reported that by 1987, the potentiometric surface in 

the Ozark aquifer had declined 350 ft from predevelopment 

conditions and that the cone of depression was expanding 

in area. The Imes (1989) groundwater-model area included 

most of Greene and Christian Counties, and parts of eight 

adjacent counties. The model that is described in this report 

covers a larger area than the Imes (1989) model and contains 

nearly all of the Imes (1989) model area (fig. 1). The Imes 

(1989) groundwater model was composed of two layers with 

variably spaced cells having the smallest cells, approximately 

0.5 mile (mi) on a side, concentrated in the Springfield area 

and the largest cells, approximately 2 mi on a side, located 

at the lateral model boundaries. Using projected growth, the 

groundwater model simulated 150 ft of additional decline in 

water levels at large pumping centers by the year 2010. 

Imes and Emmett (1994) discussed the regional 

geohydrology and presented a regional groundwater model 

in their Central Midwest Regional Aquifer-Systems Analysis 

(CMRASA) study. The model cells of the CMRASA 

groundwater model had an area of 195.3 mi2. The CMRASA 

model only simulated predevelopment conditions and did not 

simulate effects of pumping. 

Miller and Vandike (1997) reported that by 1996, 

water levels in the center of the cone of depression had 

dropped approximately 500 ft from predevelopment levels. 

At the lowest measured point in the cone of depression in 

1996, the water level in the Ozark aquifer was approximately 

259 ft below the top of the Ozark aquifer, and approximately 

1,067 ft of the Ozark aquifer remained saturated. Using 

water-level data and geographic information system (GIS) 

software to map the cone of depression in the Springfield 

area, Dintelmann and others (2006) concluded that the cone 

had expanded to the south. During 2006 and 2007, the USGS 

collected water-level measurements in 115 wells located 

within this model area and produced a potentiometric-surface 

map of the Ozark aquifer (fig. 3; Richards and Mugel, 2008). 

To the west of this study area, Gillip and others (2008) 

presented potentiometric-surface maps of the Springfield 

Plateau and Ozark aquifer constructed from 285 water levels 

measured in 2006. A groundwater model of southwestern 

Missouri, southeastern Kansas, and northeastern Oklahoma 

was developed by the USGS to assess the sustainability of 

the groundwater resources in that area (Czarnecki and others, 

2009). That study incorporated several hypothetical pumpage 

scenarios ranging from a fixed pumping rate equivalent to 

the groundwater use in 2006, and a 1-, 2-, and 4-percent per 

year annual increase until 2057. Groundwater declines for 

the fixed pumping rate resulted in moderate drawdown and 

pumpage could be maintained until 2057. For any of the other 

hypothetical scenarios specifying pumpage increases, the 

model of Czarnecki and others (2009) showed large declines 

in the potentiometric surface within the Ozark aquifer around 

the major pumping centers by the year 2057 or earlier, and that 

pumpage increases of 1-, 2-, and 4-percent per year could not 

be maintained in some parts of the model area.
6 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 3. Potentiometric surface of the Ozark aquifer 2006–07 and outcrop areas of the hydrogeologic units in the study area.

CHESAPEAKE FAULT

BATTLEFIELD-SAC RIVER FAULT

GRAYDON SPRINGS FAULT

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River Stockton Lake

Fellows

Lake McDaniel Lake

Lake

Springfield

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Approximate area of unsaturated

Ozark aquifer induced by 

groundwater withdrawal

1,200

1 1, 00

800

1,400

1 3, 00

1 2, 00

800

1,100

900

900

900

1,000

2, 1 00

1 1, 00

1 3, 00

1 0, 00

1,000

1 1, 00

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15 Potentiometric surface data from

Richards and Mugel, 2008

Geologic data modified from Missouri 

Department of Natural Resources, 2007

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

Western Interior Plains  confining systemSpringfield Plateau aquiferOzark confining unitOzark aquiferPotentiometric contour

—

 Shows altitude at which water  would have stood in tightly cased well. Contour interval 100 feet.  Datum is National Geodetic Vertical Datum 1929.

900

Fault—bar and ball on down- thrown side

A'

A

B

B'

Cross-section trace and identifier (Cross-sections shown on figure 6 and figure 7.) 

A A'
Introduction 7

Approach

Hydrologic data such as the configuration of the 

hydrogeologic units and their hydraulic properties, transient 

water-level measurements in the aquifers, the spatial 

distribution and the observed flows of the rivers and springs, 

the location and level of lakes, transient groundwater use 

from wells, and areal recharge estimates were compiled 

for the study area, which is the same as the model area. 

These data are used in the construction and calibration of a 

groundwater-flow model.

The configuration of the tops and bottoms of the 

hydrogeologic units were constructed from well logs obtained 

from the Missouri Department of Natural Resources 

(DNR; Missouri Department of Natural Resources, 2007) 

logged wells database. Locations of major faults were 

obtained from the digital geologic map (Missouri Department 

of Natural Resources, 2007). Land-surface elevations for top 

of the model were developed by computing the mean elevation 

for each model cell from the 10-meter USGS Digital Elevation 

Model (DEM) data (http://ned.usgs.gov/). 

Hydraulic properties of hydrogeologic units were 

compiled from available sources and computed, in the case 

of hydraulic conductivity, from specific-capacity data where 

available. These values were used as initial estimates in 

the model and were subsequently modified during model 

calibration to improve the agreement between simulated head 

and observed water-level altitudes and river flows. 

Water levels measured in wells in the model area in 

2006–07 were compared to historical water levels to evaluate 

water-level trends, determine groundwater-flow direction, 

and provide water-level observation data used in the model 

calibration. After construction data for the wells were 

evaluated to determine their suitability, additional water-level 

observation points were selected from the USGS National 

Water Information System (http://water.data.usgs.gov/nwis) 

database and the Missouri Department of Natural Resources 

(2007) certified well and well log databases. 

Locations of surface-water bodies were obtained from 

the national hydrography dataset for major rivers and lakes in 

the model area (http://nhd.usgs.gov/). Low-flow seepage-run 

data, collected as a series of stream-discharge measurements 

at intervals along a stream reach, assembled by the USGS 

in 2006 for this study, and 7-day annual low-flow discharge 

values for the 2-year recurrence interval (7Q2) computed at 

USGS gaged sites were used to estimate base-flow rates at 

selected sites. Altitudes of rivers represented in the model 

were obtained from DEM data. Locations, orifice altitudes, 

and base-flow estimates of major springs in the model area 

were obtained from the Missouri Department of Natural 

Resources (2007) spring location database. 

Groundwater-use data prior to 1962 was estimated. 

Groundwater-use data were compiled for the period 1962 to 

2006 from USGS records, the Missouri DNR major water-user 

database (data on file at the Missouri Department of Natural 

Resources Division of Geology and Land Survey in Rolla, 

Missouri), census of Missouri public-supply reports 

(Missouri Department of Natural Resources, 1962–2006), 

and field reconnaissance by Greene County personnel. Water 

suppliers in the model area also were contacted and most 

supplied daily, weekly, monthly, or annual groundwater-use 

records that were assembled for use in the groundwater model.

Areal recharge estimates within the model area were 

compiled from available reported values and estimated using 

the water-table fluctuation method described in Risser and 

others (2005). Recharge estimates were modified in zones 

during model calibration. 

A conceptual model of the flow system was developed 

based on the assembled hydrogeologic data. The conceptual 

model describes the general inflow and outflow mechanisms, 

flow direction, material properties, and boundary conditions 

of the groundwater-flow system within the model area. After 

a conceptual model of the flow system was developed, a 

digital model of groundwater flow was constructed using 

MODFLOW-2005 (Harbaugh, 2005). Hydrogeologic 

data were specified within the model through use of GIS 

software, and hydrologic-boundary conditions were specified 

in accordance with the conceptual model. The model was 

calibrated by minimizing the difference between simulated 

head and observed water levels and simulated and observed 

flows in rivers and springs. Response of the flow system to 

selected hypothetical future pumping and recharge stresses 

was then simulated using the calibrated model. Results from 

the simulations were compared primarily by examining 

differences in head.

Description of Model Area

The model area is located on the eastern edge of the 

Springfield Plateau physiographic section (Fenneman, 

1938) and is roughly centered on the city of Springfield, 

Missouri. The model area encompasses approximately 

2,870 mi2 and contains parts of 11 counties (fig. 2). Greene 

County is represented in its entirety in the model area, and 

nearly all of Webster and Christian Counties are included. 

Additionally, smaller areas of Barry, Dade, Dallas, Douglas, 

Laclede, Lawrence, Polk, and Stone Counties are included in 

the model area.
8 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

The land surface (fig. 4) is characterized by gently 

rolling hills in the central and western part of the model 

area where the Springfield Plateau aquifer is present at the 

surface (fig. 3). The land surface has steeper slopes in the 

northeastern and southeastern part of the model area where the 

Ozark aquifer is present at the surface (fig. 3). Numerous karst 

features such as sinkholes, losing streams, springs, caves, and 

solution-enlarged fractures are present in the model area at the 

land surface (fig. 5). The density of karst features is higher in 

the Springfield Plateau aquifer compared to the Ozark aquifer. 

A consequence of the existence of the karst features is the 

rapid flow of groundwater through the solution-enlarged joints 

and fractures and the emergence of the water as springs where 

the channels intersect the land surface. Historically, springs 

were a valuable source of drinking water, and their cool water 

was used for refrigeration by early settlers of the area (Bullard 

and others, 2001; City Utilities of Springfield, 2009). Even 

today, Fulbright Spring is a source of public-water supply for 

Springfield (fig. 2; Watershed Committee of the Ozarks, 2009).

The maximum land-surface altitude, 1,740 ft, occurs 

in the east-central part of the model area and the minimum 

land-surface altitude, 805 ft, occurs in the northwestern part of 

the model area (fig. 4). A topographic drainage divide crosses 

the model area approximately west to east with surface-water 

drainage to the north of this divide flowing to tributaries of 

the Spring River Basin (Honey Creek), the Sac River Basin, 

the Niangua River Basin, and the Gasconade River Basin. 

Surface-water drainage to the south of the topographic divide 

flows to tributaries of the James River Basin and the White 

River Basin (Bull Creek, Swan Creek, Little Beaver Creek, 

and Beaver Creek). There are four large lakes are in the model 

area. McDaniel Lake and Fellows Lake are impoundments on 

the Little Sac River north of Springfield, Lake Springfield is 

on the James River south of Springfield, and Stockton Lake is 

on the Sac River in the northwestern corner of the model area.

Mean annual precipitation in the region during 1971–2000 

was 44.97 inches (National Climatic Data Center, 2008). 

Annual precipitation ranged from 25.21 inches in 1953 to 

62.45 inches in 1927 from 1915 to 2006 in the model area. 

For the 20-year transient model-calibration period between 

1987 and 2006, annual precipitation ranged from 34.07 inches 

in 1989 to 61.29 inches in 1990 and was less than the mean 

value 12 times.

Hydrogeologic Setting of the Ozark 

Plateaus Aquifer System

Groundwater recharge to the Springfield Plateau and 

Ozark aquifers occurs from precipitation that infiltrates 

directly into the aquifer where the aquifer is exposed at 

the land surface. Groundwater generally flows away from 

groundwater highs that roughly coincide with the topographic 

divides and discharges to rivers, lakes, or springs; is 

captured by pumping wells; or flows out of the model area. 

Groundwater can also flow into the model area from outside 

the model area. 

Imes and Emmett (1994) identified and described the 

hydrogeologic units in the model area as part of a regional 

study of the Ozark Plateaus aquifer system (fig. 1). Each 

hydrogeologic unit consists of rocks with similar hydraulic 

properties, and the boundaries of hydrogeologic units 

coincide with geologic formation boundaries. Seven units 

from stratigraphically youngest to oldest include (1) the 

Western Interior Plains confining system, (2) the Springfield 

Plateau aquifer, (3) the Ozark confining unit, (4) the Ozark 

aquifer, (5) the St. Francois confining unit, (6) the St. Francois 

aquifer, and (7) the Basement confining unit. The sequence 

of hydrogeologic units from the Springfield Plateau aquifer 

through the St. Francois aquifer composes the Ozark Plateaus 

aquifer system. Erosion in the model area has exposed the 

Western Interior Plains confining system, the Springfield 

Plateau aquifer, the Ozark confining unit, and the Ozark 

aquifer hydrogeologic units (figs. 3, 6, 7, and table 1). 

Geologic formations that compose the Ozark Plateaus aquifer 

system dip to the northwest and range from Mississippian to 

Cambrian in age. The less permeable Western Interior Plains 

confining system overlies the Ozark Plateaus aquifer system 

and consists of Pennsylvanian- to Mississippian-age rocks. 

Igneous rocks of Precambrian age underlie the Ozark Plateaus 

aquifer system and make up the Basement confining unit. 

Detailed discussion of the hydrogeologic units can be found 

in Imes and Emmett (1994), Imes (1989), and Czarnecki and 

others (2009). Detailed discussion of the rocks that constitute 

the geologic formations can be found in Thompson (1995). 

The Western Interior Plains confining unit is present only as 

isolated channel-sand deposits (fig. 3) too permeable and too 

thin to form an effective barrier to the percolation of water 

from the land surface to the underlying Springfield Plateau 

aquifer. Because the Western Interior Plains confining unit 

is localized and not hydrologically significant in the model 

area, its thickness was added to the Springfield Plateau aquifer 

in the model. No additional information about the Western 

Interior Plains confining unit will be presented in this report. 

The St. Francois aquifer is hydrologically separated from 

the Ozark aquifer by the St. Francois confining unit. In the 

model area, there is no significant use of groundwater from 

the St. Francois aquifer because it is too deep and has a 

low yield (Imes, 1989). The Basement confining unit is an 

insignificant source of water. The St. Francois confining unit, 

the St. Francois aquifer, and the Basement confining unit are 

not included in the groundwater model. Figure 8 shows a map 

of the distribution of hydrogeologic units that were used in 

the model. A brief discussion of the remaining hydrogeologic 

units in the model area follows.
Hydrogeologic Setting of the Ozark Plateaus Aquifer System 9 Figure 4. Altitude of the land surface in the model area.

EXPLANATION

1,740

805

Land-surface altitude, in feet Datum is National Geodetic  Vertical Datum of 1929

Springfield

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River Stockton Lake

Fellows

Lake McDaniel Lake

Lake

Springfield

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

Data from Missouri Spatial Data Information Service

10-meter digital elevation model, 2003

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS
10 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 5. Distribution of karst features at the land surface in the model area.

Incorporated area

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River

EXPLANATION

Losing StreamSinkholeSpring

Stockton

Lake

Fellows

Lake McDaniel Lake

Lake

Springfield

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

Data from Missouri Department

of Natural Resources, 2007

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS
Hydrogeologic Setting of the Ozark Plateaus Aquifer System 11Figure 6. Northwest to southeast cross section from A to A’ (on fig. 3) of the hydrogeologic units in the model area with model layers indicated.

Model layer 2 bottom

Model layer 3 bottom

Model layer 1 bottom

Note: Small outliers of Western Interior Plains confining systemomitted for clarity

2006 Potentiometric head

in the Ozark aquifer

St. Francois confining unit

and underlying hydrogeologic units

Ozark aquifer

2,0001,5001,000

500

NGVD 29

-500

A A'

Sac River

Finley Creek

Little Beaver Creek

Swan Creek

Beaver Creek

James River

Stockton Lake

SPRINGFIELD

Intersection of 

 B - B’ trace

FEET

0 2 4 6 8 10 KILOMETERS

0 2 4 6 8 10 MILES

VERTICAL SCALE GREATLY EXAGGERATED

Ozark confining unit

Springfield Plateau aquifer
12 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 7. Southwest to northeast cross section from 

B to B’ (on fig. 3) of the hydrogeologic units in the model area with model layers indicated.

Chesapeake Fault

Battlefield-Sac River Fault

Pomme de terre River

Little Sac River

Niangua River

Wilsons Creek

Crane Creek

SPRINGFIELD

Intersection of 

A - A’ trace 

Ozark confining unit

Ozark aquifer

St. Francois confining unit

and underlying hydrogeologic units

Springfield Plateau aquifer

B B'

2,0001,5001,000

500

NGVD 29

-500

Model layer 2 bottom

Model layer 3 bottom

Model layer 1 bottom

Note: Small outliers of Western Interior Plains confining system omittedfor clarity

2006 Potentiometric head

in the Ozark aquifer

0 2 4 6 8 10 KILOMETERS

0 2 4 6 8 10 MILES

VERTICAL SCALE GREATLY EXAGGERATED

FEET

EXPLANATION

Fault showing relative movement. Dashed where inferred
Hydrogeologic Setting of the Ozark Plateaus Aquifer System 13

Table 1. Correlation of hydrogeologic units and stratigraphic units in the model area (modified from Imes, 1989).

System Hydrogeologic system Hydrogeologic unit Stratigraphic unit Lithology Water-bearing properties

Pennsylvanian

Western Interior Plains 

confining system

Western Interior Plains 

confining unit

Pennsylvanian

channel-sand deposits Sandstone and shale

Hydraulic properties are 

unknown. Presumably, most of these localized, thin deposits are unsaturated.

Mississippian

Ozark Plateaus

aquifer system

Springfield Plateau aquifer

St. Louis Limestone

Limestone and chert

Karst aquifer. Yield to wells 

usually is less than 20 gallons per minute. Adequate for domestic and stock use only. Contamination potential large because of extensive network of karst features andsurficial position.

Salem FormationWarsaw FormationKeokuk LimestoneBurlington LimestoneElsey FormationReeds Spring FormationPierson Limestone

Ozark confining unit

Northview Shale

Shale, siltstone,

and limestone

Confining unit with confining 

material primarily in the Northview Shale.

Compton LimestoneBachelor Formation

Devonian Chattanooga ShaleOrdovician

Ozark aquifer

Smithville Dolomite

Dolomite and sandstone

Productive aquifer yielding 

about 1,000 gallons per minute to wells open to the entire sequence of rock units. Upper part of aquifer generally is less productive. Most productive rock units are the Roubidoux Formation, Gasconade Dolomite, and thePotosi Dolomite.

Cotter DolomiteJefferson City DolomiteRoubidoux FormationGasconade Dolomite

Cambrian

Eminence DolomitePotosi Dolomite

St. Francois confining unit

Doe Run Dolomite

Shale, siltstone, dolomite, 

and limestone

Confining unit with confining 

material primarily in the Davis Formation.

Derby DolomiteDavis Formation

St. Francois aquifer

Bonneterre Formation

Sandstone and dolomite

Aquifer not used in model area 

because of aquifer depth and small yield

Reagan SandstoneLamotte Sandstone

Precambrian No system recognized Basement confining unit Igneous and metamorphic rocks Igneous and metamorphic rocks Insignificant as a source of water
14 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Springfield Plateau Aquifer 

The Springfield Plateau aquifer is present in most of 

the model area (figs. 3 and 8) and ranges in thickness from 

0 where it has been removed by erosion to 350 ft (fig. 9). 

It is a sequence of permeable, partially saturated rocks of 

Mississippian age. The stratigraphic units, from youngest 

to oldest, that comprise the Springfield Plateau aquifer 

include the St. Louis Limestone, Salem Formation, Warsaw 

Formation, Keokuk Limestone, Burlington Limestone, Elsey 

Formation, Reeds Spring Formation, and Pierson Limestone 

(table 1). These rock units are dominantly coarse crystalline 

and cherty limestone. The Keokuk Limestone and Burlington 

Limestone are the most permeable rock units and, where 

saturated, probably yield more water to wells than the other 

rock units (Miller and Vandike, 1997). Wells open only to the 

Springfield Plateau aquifer typically yield less than 20 gallons 

per minute (gal/min) and are only suitable for domestic and 

stock use (Imes, 1989). The water table in the Springfield 

aquifer is about 100 ft below the land surface in the recharge 

areas and is at the land surface in the larger stream valleys 

where the groundwater discharges to streams (Imes, 1989).

Because the Springfield Plateau aquifer occurs at the 

surface, the altitude of the top of the Springfield Plateau 

aquifer is the land-surface altitude. The thickness of the 

Springfield Plateau aquifer (fig. 9) was determined by 

subtracting the land-surface altitude from the altitude of the 

top of the Ozark confining unit. Occurrence of the Western 

Interior Plains confining unit in the model area (fig. 3) was 

assumed to be hydrologically unimportant, and its thickness 

was added to the thickness of the underlying Springfield 

Plateau aquifer in those areas.

Karst features such as solution-enlarged fractures, caves, 

sinkholes, losing streams, and springs are present in the 

Springfield Plateau aquifer (fig. 5). These karst features are 

formed by dissolution of the limestone by groundwater, rich 

in carbonic acid, as it percolates through the unsaturated zone 

to the water table. Locally, these features are hydrologically 

important because they can quickly move water and 

contaminants into and through the groundwater system and 

can move groundwater between surface-water drainage basins. 

Sinkhole density in the Springfield Plateau aquifer is greater 

than 10 sinkholes per 100 mi2 throughout much of the model 

area (Harvey, 1980).

Estimates of hydraulic properties of the Springfield 

Plateau aquifer in the model area are sparse. Previously 

published values are presented in table 2 and will be discussed 

in greater detail in the Hydraulic Property Estimation section 

of the report. 

Ozark Confining Unit

The Ozark confining unit is present in most of the model 

area (figs. 3, 8, and 10). It ranges in thickness from 0 ft, 

where it has been removed by erosion, to about 98 ft, and 

is thickest in the northern part of the model area (fig. 11). 

The Ozark confining unit retards groundwater flow between 

the Springfield Plateau aquifer and the Ozark aquifer. It is 

primarily composed of fine-grained limestone, siltstone, 

and shale of the Kinderhookian Series of Mississippian age 

and locally present shale of Devonian age. The stratigraphic 

units, from the youngest to the oldest, that compose the 

Ozark confining unit are the Northview Shale, Compton 

Limestone, Bachelor Formation, and Chattanooga Shale 

(table 1). The Northview Shale is the primary confining bed 

in the Ozark confining unit although the limestone formations 

can act as confining beds where secondary porosity is absent 

(Imes, 1989). The Northview Shale generally thins from 

a maximum thickness of about 80 ft in the northern and 

northeastern part of the model area to less than 10 ft in the 

southwestern part of the model area (Imes, 1989). The Ozark 

confining unit is exposed along streams and rivers where the 

Springfield Plateau aquifer has been eroded away. 

The configuration of the top (fig. 10) and bottom of 

the Ozark confining unit was mapped from 1,042 well 

logs obtained from the Missouri DNR. Only well logs that 

intersected both the top and the bottom of the Ozark confining 

unit were used. The thickness map of the Ozark confining 

unit (fig. 11) was constructed by contouring the thicknesses 

obtained from the 1,042 well logs. In areas of overlap between 

the two model areas, these maps of the Ozark confining unit 

were similar to the maps of Imes (1989). Differences were 

noted in some areas but were largely the result of new data not 

available to Imes (1989).

Estimated values of the hydraulic properties for the 

Ozark confining unit in the model area are scarce. Previously 

published values are presented in table 2 and will be discussed 

in greater detail in the Hydraulic Property Estimation section 

of the report. 

Ozark Aquifer

The Ozark aquifer is the primary bedrock aquifer in 

southern Missouri, providing most of the private and public 

water supplies in the region. It is present across the model 

area and is much thicker than the Springfield Plateau aquifer 

(figs. 6 and 7). It is composed of dolomite and sandstone of 

Cambrian and Ordovician age (table 1). The stratigraphic 
Hydrogeologic Setting of the Ozark Plateaus Aquifer System 15Figure 8. Distribution of the hydrogeologic units at the upper surface of the cells in layer 1 and water-level observations used for calibration in the model.

EXPLANATION

Springfield Plateau aquiferOzark confining unitOzark aquiferLayer 1 water-level  observation pointLayer 3 water-level observation point

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River Stockton Lake

Fellows

Lake McDaniel Lake

Lake

Springfield

CHESAPEAKE FAULT

BATTLEFIELDSAC RIVER FAULT

GRAYDON SPRINGS 

FAULT

Fault—bar and ball on  down-thrown side

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS
16 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 9. Thickness of the Springfield Plateau aquifer in the study area.

CHESAPEAKE  FAULT

BATTLEFIELD-SAC RIVER FAULT

GRAYDON SPRINGS  FAULT

Fault—bar and ball on downthrown side

EXPLANATION

Thickness, in feet

Not presentgreater than 0 to 100greater than 100 to 200greater than 200 to 300greater than 300LakeRiver

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15
Hydrogeologic Setting of the Ozark Plateaus Aquifer System 17

Table 2. Reported hydraulic property values for the model area and vicinity.[ft, foot; ft2/d, square foot per day; 1/ft, per foot; ft/d, foot per day; 1/d, per day; K, hydraulic conductivity; MO, Missouri; KS, Kansas; OK, Oklahoma; >, greater than; <, less than; —, no data]

Location Thickness (ft) Transmissivity (ft2/d)

Storage 

coefficient

(dimensionless)

Specific storage

(1/ft)

Specific yield

(dimensionless)

Horizontal K

(ft/d)

Vertical K

(ft/d)

Leakance

(1/d) Reference

Springfield Plateau aquifer

Springfield, MO 0-300 860-4,320 — — 2.00x10-2 4.3-43 — — Imes, 1989, p. 1, 12Greene

County area 0-400 3,450-8,640 — — — 21.6 — — Imes and Emmett, 1994, p. 107, fig. 68

Ottawa

County, OK 300 390-10,500 — 1.0x10-5 2.00x10-1 1.3-35 2.6x10-2 - 7.0x10-1 — Reed and Czarnecki, 2006, p. 14, fig. 8

Tristate area

(MO, OK, KS) 0-400 — — 5.0x10-6 - 1.0x10-5 1.00x10-2 - 1.00x10-1 0.89-35 2.97x10-4 - 1.00 — Czarnecki and others, 2009, p. 27

Ozark confining unit

Springfield, MO — — — — — — 8.6x10-5 — Emmett and others, 1978Springfield, MO 0-100 — — — — — 7.8x10-6 and 9.5x10-6 — Imes, 1989, p. 1, 52Ottawa

County, OK

— — — — — — — 4.3x10-8 - 7.7x10-8 Christenson and others, 1994, p. 23

Greene

County area

— — — — — — 1.7x10-3 - 4.3x10-3 5.2x10-5 - 1.7x10-4 Imes and Emmett, 1994, p. 111, fig. 69

Tristate area

(MO, OK, KS) 0-100 — 5.0x10-6 1.00x10-1 1.0x10-5 - 4.0x10-5 2.0x10-7 - 2.45x10-5 Czarnecki and others, 2009, p. 27

Ozark aquifer

Springfield, MO — 670-3,974 — — — — — — Emmett and others, 1978, p. 30, 112Springfield, MO <1,000 - >1,450 — 1.0x10-4 — 1.00x10-3 - 2.00x10-2 0.7-2.6 — — Imes, 1989, p. 1, 23, 52 Fig. 14Springfield, MO 1,200 2,146 - 2,821 1.6x10-4 — — 2.11 — — Vandike and Sherman, 1994, p. 53-54Greene

County area

— 8,640 - 14,688 — — — 6.91 - 11.23 — — Imes and Emmett, 1994, p. 49

Tristate area

(MO, OK, KS) 700-1,500 — — 1.00x10-7 - 3.97x10-5 3.56x10-4 - 7.50x10-2 0.10 - 5.00 5.00x10-3 - 1.81 — Czarnecki and others, 2009, p. 27

St. Francois confining unit

Springfield, MO 250 — — — — — 3.8x10-6 — Imes, 1989, p. 52Springfield, MO 250 — — — — — 8.6x10-4 — Imes and Emmett, 1994, p. 114, fig. 71
18 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 10. Configuration of the top of the Ozark confining unit in the study area.

CHESAPEAKE FAULT

BATTLEFIELD-SAC RIVER FAULT

GRAYDON SPRINGS  FAULT

Fault—bar and ball on downthrown side

EXPLANATION

Not presentgreater than 700 to 800greater than 800 to 900greater than 900 to 1,000greater than 1,000 to 1,100greater than 1,100 to 1,200greater than 1,200 to 1,300greater than 1,300 to 1,400greater than 1,400 to 1,500greater than 1,500 to 1,600greater than 1,600Lake

Altitude, in feet

River

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS
Hydrogeologic Setting of the Ozark Plateaus Aquifer System 19Figure 11. Thickness of the Ozark confining unit in the study area. CHESAPEAKE FAULT BATTLEFIELD-SAC RIVER FAULT

GRAYDON  SPRINGS  FAULT

Fault—bar and ball on downthrown side

EXPLANATION

Not presentgreater than 0 to 10greater than 10 to 20greater than 20 to 30greater than 30 to 40

Thickness, in feet

greater than 40 to 50greater than 50 to 60greater than 60 to 70greater than 70 to 80greater than 80 to 90greater than 90 to 100

LakeRiver

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS
20 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

units, from the youngest to the oldest, that comprise the Ozark 

aquifer in the model area are the Smithville Dolomite, Cotter 

Dolomite, Jefferson City Dolomite, Roubidoux Formation, 

Gasconade Dolomite, Eminence Dolomite, and Potosi 

Dolomite (table 1). 

The altitude of the top of the Ozark aquifer (fig. 12) was 

obtained by subtracting the Ozark confining unit thickness 

map from the altitude of the top of the Ozark confining unit 

map. Land-surface altitudes were used where the Ozark 

aquifer is exposed at the surface. The thickness of the Ozark 

aquifer (fig. 13) was obtained by subtracting the altitude of the 

top of the Ozark aquifer map from the altitude of the top of 

the St. Francois confining unit map. In areas of overlap, these 

maps of the Ozark aquifer were similar to the maps of Imes 

(1989). Differences were noted in some areas but were largely 

the result of new data not available to Imes (1989).

The aquifer is about 900 ft thick in the northwestern 

part of the model area and thickens to about 1,780 ft in the 

southeastern part of the model area (fig. 13). In most of the 

model area, it is a confined aquifer with a potentiometric 

surface above the top of the aquifer. The aquifer is exposed 

and is unconfined in the northeastern and southeastern parts 

of the model area and along some streams. The aquifer is also 

unconfined where groundwater pumpage has lowered the 

potentiometric surface below the base of the Ozark confining 

unit (fig. 3). Although some karst features exist in the Ozark 

aquifer in the model area, karst terrane is not nearly as well 

developed in the Ozark aquifer as it is in the Springfield 

Plateau aquifer.

Wells that are open to the entire Ozark aquifer typically 

yield about 1,000 gal/min, which is sufficient to supply 

municipal and industrial needs (Vandike and Sherman, 1994). 

The formations within the Ozark aquifer that yield the greatest 

amount of water are the Roubidoux Formation, Gunter 

Sandstone Member of the Gasconade Dolomite, and the 

Potosi Dolomite (Imes, 1989; Vandike and Sherman, 1994). 

Wells completed in the Jefferson City and Cotter dolomites 

usually yield less than 50 gal/min.

Estimates of the hydraulic properties of the Ozark aquifer 

in the model area are sparse. Previously published values are 

presented in table 2 and will be discussed in greater detail in 

the Hydraulic Property Estimation section of the report. 

St. Francois Confining Unit

Although the St. Francois confining unit is not 

represented as a specific layer in the model, this unit is used 

to define the bottom of the Ozark aquifer, and the hydraulic 

properties of this unit regulate flow through the bottom 

of the Ozark aquifer. The St. Francois confining unit is 

approximately 250 ft thick and retards groundwater flow 

between the overlying Ozark aquifer and the underlying 

St. Francois aquifer (Imes, 1989). It is composed of shale, 

siltstone, dolomite, and limestone of Cambrian age. The 

formations that make up the St. Francois confining unit are 

the Doe Run Dolomite, the Derby Dolomite, and the Davis 

Formation (table 1). 

The Missouri DNR well-log data for the St. Francois 

confining unit were relatively sparse. The altitude of the top 

of the St. Francois confining unit was contoured from 

51 wells that penetrated into or through the unit in the 

general model area (fig. 14). In areas of overlap, the map was 

similar to the map of Imes (1989). Differences were noted 

in some areas but were largely the result of new data not 

available to Imes (1989).

Conceptual Model of the GroundwaterFlow System

Part of a modeling process is to develop a conceptual 

model of the groundwater-flow system to explain flow 

within the study area by identifying sources and sinks of 

water. The conceptual model is the basis for developing the 

digital model and takes into account annual precipitation, 

topography, properties and distribution of the hydrogeologic 

units, hydrologic boundaries, current and past water-level data, 

pump-test data, water-quality data, and previously published 

interpretations of the flow system. 

The two principal aquifers within the model area are the 

Springfield Plateau aquifer and the Ozark aquifer, with the 

Ozark aquifer being more important in terms of water supply. 

Recharge occurs in the model area through infiltration of 

precipitation that falls on the land surface. Groundwater can 
Conceptual Model of the Groundwater-Flow System 21Figure 12. Configuration of the top of the Ozark aquifer in the study area. CHESAPEAKE FAULT BATTLEFIELD-SAC RIVER FAULT

GRAYDON SPRINGS FAULT

Fault—bar and ball on downthrown side

EXPLANATION

less than 700greater than 700 to 800greater than 800 to 900greater than 900 to 1,000greater than 1,000 to 1,100greater than 1,100 to 1,200greater than 1,200 to 1,300greater than 1,300 to 1,400greater than 1,400 to 1,500greater than 1,500 to 1,600

Altitude, in feet

LakeRiver

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS
22 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 13. Thickness of the Ozark aquifer in the study area.

CHESAPEAKE FAULT

BATTLEFIELD-SAC 

RIVER FAULT

GRAYDON 

SPRINGS FAULT

Fault—bar and ball on downthrown side

EXPLANATION

less than 900greater than 900 to 1,000greater than 1,000 to 1,100greater than 1,100 to 1,200greater than 1,200 to 1,300greater than 1,300 to 1,400greater than 1,400 to 1,500greater than 1,500 to 1,600

Thickness, in feet

greater than 1,600 to 1,700greater than 1,700 to 1,800LakeRiver

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS
Conceptual Model of the Groundwater-Flow System 23Figure 14. Configuration of the top of the St. Francois confining unit in the study area. CHESAPEAKE FAULT

BATTLEFIELD-SAC  RIVER FAULT

GRAYDON  SPRINGS  FAULT

Fault—bar and ball on downthrown side

EXPLANATION

less than -400

greater than -400 to -300greater than -300 to -200greater than -200 to -100greater than -100 to 0greater than 0 to 100greater than 100 to 200greater than 200 

Altitude, in feet

LakeRiver

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS
24 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

flow into the study area by lateral flow. Surface water can 

enter the groundwater system from rivers and lakes that have 

a stage that is higher than the head in the hydrogeologic unit 

underlying those features. Discharge from the groundwater 

system occurs at the land surface to rivers, lakes, and springs 

where the head in the hydrogeologic unit underlying those 

features is higher than the water level in those features. 

Groundwater can flow out of the study area by lateral flow. 

Groundwater also can be removed by pumping wells in the 

study area. Wells producing large amounts of water in the 

study area are typically open to almost the entire thickness of 

the Ozark aquifer (Missouri Department of Natural Resources, 

2007; Jim Vandike, Missouri Department of Natural 

Resources, oral commun., 2008). Head gradients between 

hydrogeologic units induce vertical flow through the Ozark 

confining unit and the St. Francois confining unit. 

Faults within the study area can be barriers or conduits 

to flow, but no information is available to determine which, 

if either, condition exists so the faults were ignored. Karst 

features such as sinkholes, caves, solution enlarged fractures, 

and springs exist in the study area. Groundwater flow in the 

karst area can be conceptualized as two separate but linked 

groundwater-flow systems: the karst quick-flow component 

and the slower porous-media flow component (Imes and 

others, 2007). The quick-flow component recharges rapidly 

from infiltration after precipitation events and discharges 

rapidly by flow from springs. The porous-media flow 

component slowly recharges from infiltration and from 

exchange with the groundwater in the karst system and slowly 

discharges to streams and by exchange with the karst system. 

The porous-media flow component is the part of groundwater 

flow that maintains the base flow to the streams and springs. 

Description of the Groundwater-Flow 

Model

Converting the conceptual model of groundwater flow 

into a digital numerical model requires the use of computer 

software and simplifying assumptions. The following sections 

describes the software used, the assumptions made to develop 

the model, and the specifications of the various components 

applied in the model.

Groundwater-Modeling Software

Groundwater flow was simulated using 

MODFLOW-2005 (Harbaugh, 2005), which is the USGS 

finite-difference, three-dimensional numerical modeling 

software. The approximation for spatial distribution of head 

over time was solved with the Preconditioned-ConjugateGradient (PCG) solver in the MODFLOW-2005 software 

(Harbaugh, 2005). Three-dimensional simulation of 

groundwater flow was used to determine the head distribution 

around major pumping centers in the model area, to describe 

vertical flow between adjacent units, and to represent the 

three-dimensional geometry of the flow system. GIS software 

was used for processing input data to the model and for 

display of model results (Environmental Systems Research 

Institute, 2009).

Simplifying Assumptions

Darcy’s law (Freeze and Cherry, 1979) for flow through 

a porous media was assumed to be applicable to this system. 

It was assumed that the stratigraphic rock units could be 

aggregated into the hydrogeologic units of the Springfield 

Plateau aquifer, Ozark confining unit, and the Ozark aquifer 

and that the groundwater-flow system could be represented 

by a three-layer model. Combining hydrogeologic units by 

computing composite hydraulic properties in some model cells 

was assumed to not adversely affect the distribution of head 

computed by the model. The assumption was made that there 

was flow through the lateral boundaries in the model and that 

there was vertical flow through the base of the Ozark aquifer. 

Reference head values at the lateral boundaries and at the base 

of the Ozark aquifer were assumed to be invariant throughout 

the simulation. Groundwater pumpage and recharge was 

assumed to be constant for each stress period but varied 

between stress periods. This assumption ignored seasonal 

precipitation changes or changes in pumpage within the 

stress period. It was assumed a linear relation exists between 

precipitation and recharge in the study area. Recharge was 

assumed to vary spatially based on land slope and to be less in 

Springfield because of the occurrence of impervious surface 

in the city. Hydraulic properties within a model cell were 

assumed to reflect the mean conditions over the volume of the 

cell, neglecting local variations in those properties. Horizontal 

anisotropy of the hydrogeologic units was unknown and was 

assumed to be negligible at the model scale. Assumptions were 
Description of the Groundwater-Flow Model 25

made that faults in the model area do not alter groundwater 

flow and that the karst development in the Springfield Plateau 

aquifer and the Ozark aquifer was extensive enough that the 

hydrogeologic units could be represented as porous media 

for the model grid spacing. It also was assumed that the 

karst, quick-flow component of the groundwater-flow system 

occurred during a short enough period when compared to the 

stress period length that it would not substantially alter the 

longer-term porous-media flow system. All pumping wells 

were assumed to be open to the full thickness of the model.

 Attempts to simulate all layers in the model as 

unconfined were unsuccessful because the model became 

unstable and the simulation failed to converge. By necessity, 

it was assumed that model layers 2 and 3 were confined and 

that simulating layers 2 and 3 as confined in the model would 

provide reasonable estimates of the head distributions in 

these layers.

Model Specifications

The numerical model has four main components: 

(1) the finite difference grid, (2) stress-period discretization, 

(3) model boundary conditions, and (4) groundwater use. 

Each of these components will be discussed in the 

following sections. 

Finite-Difference Grid

The model was subdivided into a regularly spaced grid of 

253 rows and 316 columns. Each model cell was 1,000 ft by 

1,000 ft in size representing an area of 0.036 mi2. The model 

grid was oriented north and south and all cells were active in 

the model. 

Initial Hydrogeologic Unit Discretization

The initial unsuccessful discretization of the model area 

divided the model into three layers of variable thickness along 

the contacts between the Springfield Plateau aquifer, Ozark 

confining unit, and the Ozark aquifer. Land-surface altitude 

(fig. 4) for each model cell in layer 1 was determined by 

computing the mean of the 10-meter (32.8 ft) DEM values 

within each cell. Using the model grid as a base, altitudes of 

the tops of the hydrogeologic units were discretized for each 

cell from the maps shown in figure 10, 12, and 14. Because 

the rock units dip slightly and the topographic surface is an 

erosional surface, the hydrogeologic units of the Springfield 

Plateau aquifer and Ozark confining unit become thin along 

their contact areas. Natural groundwater fluctuation can allow 

the hydrogeologic units along this contact zone to become 

unsaturated. During the initial unsuccessful attempt of model 

calibration (see Model Calibration section), the model solution 

oscillated at several nodes in layer 1 where the Springfield 

Plateau aquifer was thin and the saturated thickness becomes 

small. This oscillation led to a numerical instability around 

cells that would alternately go wet and dry as the mathematical 

solver attempted to determine a solution, causing the model to 

fail to converge. This problem was also noted in the model of 

Imes (1989). Cells in this area of layer 1 were inactivated in 

an attempt to solve the numerical instability problem. The area 

of inactive cells grew to cover parts of the Springfield Plateau 

aquifer known to be saturated. In addition, recharge to the 

model was affected because nearly 25 percent of the cells in 

the Springfield Plateau aquifer were inactive. The model never 

became stable using this discretization.

Final Hydrogeologic Unit Discretization

To alleviate the numerical instability near the edge 

of the saturated area of the Springfield Plateau aquifer, the 

model was rediscretized so that the cells in layer 1 would 

always remain partially saturated and not go dry. This was 

accomplished by determining the approximate mean head 

for each surficial cell in the model then computing the 

estimated minimum head that could occur because of temporal 

fluctuation. The bottom elevation of the cell was assigned to 

be at or below the estimated minimum head in the cell. 

The final discretization of the model area divided the 

model into three layers. Layers 1 and 3 were of variable 

thickness, and layer 2 was a constant 100-ft thickness. Landsurface altitude (fig. 4) for each model cell in layer 1 was 

determined by computing the mean of the 10-meter (32.8 ft) 

DEM values within each cell. A conceptual cross section 

of model layers is shown in figure 15 and helps illustrate 

in the following discussion how the model layers were 

determined. In areas where the Springfield Plateau aquifer 

is present and is of sufficient thickness, cells in layer 1 of 

the model are composed entirely of Springfield Plateau 

aquifer (fig. 15, cell A). Layer 1 can also be composed of 

a combination of Springfield Plateau aquifer and Ozark 

confining unit (fig. 15, cell B) or composed of a combination 

of Springfield Plateau aquifer, Ozark confining unit, and 

Ozark aquifer (fig. 15, cell C). Adjacent model cells with large 
26 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 15. Conceptual cross section of model layers compared with the hydrogeologic units.

LAYER 1Minimum 200-foot thicknessLAYER 2Constant 100-foot thicknessLAYER 3Variable thickness

A

B

C

E

F

G

H

I

D

Vertical

cell

boundaries

Top of model layer 1

(land surface)

Bottom

of model

layer 1

Bottom 

of model 

layer 2

Bottom of model layer 3

EXPLANATION NOT TO SCALE

St. Francois confining unit

Springfield Plateau aquiferOzark confining unit

Ozark aquifer Approximate average water table

Estimated seasonal minimum  water-table altitude

G Pattern designates the cell area; Letter designates selected cell
Description of the Groundwater-Flow Model 27

differences in thickness can cause numerical instability. A 

minimum thickness of 200 ft was specified for layer 1 so that 

adjacent model cells did not have large thickness differences 

(fig. 15, cell D). In areas where the Springfield Plateau 

aquifer is not present, layer 1 of the model is composed of 

a combination of Ozark confining unit and Ozark aquifer 

where the Ozark confining unit is present at the surface 

(fig. 15, cell E) or entirely Ozark aquifer where the Ozark 

aquifer is present at the surface (fig. 15, cell F). Layer 2 was 

assigned a constant thickness of 100 ft, which restricted the 

occurrence of the Ozark confining unit to layer 1 or layer 2. 

Layer 2 is composed of a combination of Ozark confining 

unit and Ozark aquifer (fig. 15, cell G) or composed entirely 

of Ozark aquifer (fig. 15, cell H). By definition, layer 2 does 

not contain any Springfield Plateau aquifer anywhere in the 

model. Layer 3 of the model is composed entirely of Ozark 

aquifer (fig. 15, cell I). Layer 1 and layer 3 vary in thickness. 

Figure 6 and figure 7 show cross sections (trace shown 

on figs. 3, 16, and 17) from northwest to southeast and 

southwest to northeast across the model area with the bottoms 

of the layers of the model indicated. As can be seen on 

figure 6 and figure 7, model layers 1 and 2 can be composed 

of a combination of several hydrogeologic units. Figure 16 

and figure 17 show the plan view distribution of the 

hydrogeologic units in layer 1 and layer 2 in the model. 

Hydraulic Property Computation

Because model layers can comprise multiple 

hydrogeologic units (figs. 6, 7, 15, 16, and 17), composite 

hydraulic properties for each model layer were computed. 

The horizontal and vertical composite hydraulic conductivity 

for each cell was computed based on the concepts of “branch 

conductances” (McDonald and Harbaugh, 1988). Specific 

yield and specific storage were computed by calculating the 

thickness weighted mean in each cell. For each model run, 

hydraulic properties of the various hydrogeologic units were 

specified and converted into composite hydraulic properties 

for each cell prior to executing the groundwater model. 

Stress Period Discretization

The first stress period simulated in the model was 

specified as steady state to allow the simulated head to 

come into equilibrium with the model boundary conditions. 

There was no pumping from the aquifers specified in stress 

period 1. The steady-state stress period was followed by 

100 annual transient stress periods representing the period 

from 1907 to 2006. Annual stress periods were specified so 

that groundwater-pumping rates and recharge could be varied 

annually as groundwater demand and precipitation changed 

with time. Calibration of the model was focused on the 

predevelopment steady-state stress period and on the period 

from 1987 to 2006. Predevelopment water-level data were 

obtained from the Missouri DNR well-log database (Missouri 

Department of Natural Resources, 2007) and supplemented 

with interpolated values from predevelopment potentiometric 

surface maps developed by Imes (1990a, 1990b). The USGS 

collected four (1987, 1993, 1996, and 2006) sets of synoptic 

water-level measurements from wells between 1987 and 

2006, and numerous random measurements were obtained 

from USGS databases and Missouri DNR databases for 

the calibration period. For the predictive simulation period 

from 2007 to 2030, annual stress periods were specified 

so that groundwater-pumping rates and recharge could be 

varied annually as groundwater demand and precipitation 

changed with time.

Model Boundary Conditions

Model boundary conditions were specified such that 

groundwater flow was consistent with the conceptual model. 

The flux boundary conditions were specified by using the 

RCH package of MODFLOW for areally distributed recharge, 

the RIV package of MODFLOW for flow to and from rivers, 

and the DRN package of MODFLOW for flow to springs 

(Harbaugh, 2005). The GHB package of MODFLOW 

(Harbaugh, 2005) was used for flow to and from lakes, for 

lateral flow through the boundary of the model, and for 

vertical flow through the bottom of the Ozark aquifer. Each of 

these specifications is discussed in the following sections.

Areally Distributed Recharge

Areally distributed recharge occurs at the land surface 

from infiltration resulting from atmospheric precipitation. 

Mean annual precipitation in the region for the period 

1971–2000 was 44.97 inches (National Climatic Data Center, 

2008). Some of this precipitation infiltrates into the Springfield 

Plateau aquifer and the Ozark aquifer where they are present at 

the land surface. It was assumed that there was no recharge to 

the groundwater where the Ozark confining unit is present at 

the land surface, which has a small area (fig. 8). Areal recharge 

can vary substantially and is an important model variable for 

simulating groundwater flow. 

Using a soil-moisture water-balance analysis, 

Dugan and Peckenpaugh (1986) provided estimates of 

potential recharge across the model area that ranged 

from 1.80x10-3 to 2.17x10-3 feet per day (ft/d) or 

7.9 to 9.5 inches per year (in/yr). These estimates of recharge 

were used in this model as a starting point to begin the 

calibration process. Results from these initial attempts resulted 

in head distributions that were too high and flows to the 

rivers that were too large, even with commensurate changes 
28 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 16. Distribution of hydrogeologic units in layer 1 of the model.

EXPLANATION

Composition of model layer 1

Springfield Plateau aquiferCombination of Springfield Plateau aquifer and Ozark confining unit

Combination of Springfield Plateau aquifer, Ozark  confining unit, and Ozark aquifer

Combination of Ozark confining unit and Ozark aquiferOzark aquiferCross-section trace and identifier

A A'

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

A

A'

B

B'
Description of the Groundwater-Flow Model 29Figure 17. Distribution of hydrogeologic units in layer 2 of the model.

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

Composition of model layer 2

Combination of Ozark confining unit and  Ozark aquiferOzark aquiferCross-section trace and identifier

A A'

A

A'

B

B'
30 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

in hydraulic conductivity. These estimates of recharge were 

also found to be too large in previous models completed in the 

Springfield, Missouri, area (Imes, 1989), in the regional model 

of Imes and Emmett (1994), and in the model of Czarnecki 

and others (2009) in southwestern Missouri, southeastern 

Kansas, northeastern Oklahoma, and northwestern Arkansas. 

The water-table fluctuations method (Risser and 

others, 2005) was used to estimate the minimum recharge 

to the groundwater in the Springfield Plateau aquifer at the 

Longview monitoring well in McDonald County, Missouri, 

southwest of this model area. The water-table fluctuations 

method measures the effect of recharge at the water table 

and requires that the value of specific yield for the aquifer be 

known to translate the measured water-level fluctuations into 

estimates of recharge. The method assumes that the waterlevel rise in the well is caused only by recharge arriving at 

the water table and that the specific yield of the aquifer is 

constant. Changes in the water levels were computed from the 

daily observations at the Longview monitoring well (fig. 18). 

Annual cumulative totals were obtained by summing the daily 

rise in the water level. Daily water levels that fell or that had 

no change did not change the cumulative total. The annual 

cumulative total then was multiplied by the specific yield 

value, 0.003, used in the model to determine the recharge 

value for the year. To ensure the greatest accuracy, only years 

with greater than 350 daily observations were used to compute 

the recharge value. Years with fewer data points, although 

useful for some applications, were not used in this analysis. 

Between 1984 and 2008, 8 years had greater than 350 daily 

observations resulting in calculated recharge ranging from 

1.74x10-4 ft/d to 2.09x10-4 ft/d (0.762 and 0.915 in/yr) with a 

mean recharge of 1.94x10-4 ft/d (0.849 in/yr) (table 3). This 

range of recharge is similar to that specified by Imes (1989) 

of 3.01x10-4 to 3.69x10-4 ft/d and to values specified by 

Czarnecki and others (2009) of 2.00x10-5 to 8.00x10-4 ft/d.

In this model, it was assumed that recharge varied 

spatially based on land slope. It was also assumed that 

recharge was less in the city of Springfield because of the 

distribution of impervious surface in the city (fig. 19). 

Recharge was applied to all cells in layer 1 except cells where 

the Ozark confining unit is exposed at the surface. Land slope 

was determined from the DEM and then classified into three 

zones that were used to adjust the amount of recharge being 

applied to the land surface (table 4). Lower slope values 

tend to occur in the upland areas and near streams. It was 

assumed that greater infiltration would occur in areas with 

lower slope values. This assumption is supported by the 

greater number of sinkhole occurrences that are associated 

with the relatively flat uplands in the model area (fig. 5). 

The total recharge rate was computed as approximately 

2.53 percent of the total annual precipitation observed in 

the region (table 5). It was assumed that areas covered by 

impervious surface in the city of Springfield do not contribute 

recharge to the aquifer; the city of Springfield is estimated to 

be covered by approximately 32 percent impervious surface 

(fig. 20). Within the city, the computed recharge based on land 

slope was reduced by 32 percent to account for the reduced 

potential for recharge to the aquifer (table 4). In areas where 

recharge was applied, the percentage of the total precipitation 

that became recharge to the model ranged between 1.44 and 

3.00 percent (table 4). Recharge, in areas where recharge 

was applied, for the mean annual precipitation value of 

44.97 in/yr ranged between 1.47x10-4 and 3.08x10-4 ft/d 

(0.645 in/yr and 1.35 in/yr; table 4). The total annual recharge 

to the model, from 1907 to 2006, ranged between 1.45x10-4

and 3.60x10-4 ft/d (0.637 in/yr and 1.58 in/yr) (table 5), and 

this range in recharge is similar to recharge values used in 

previous models and to the values obtained by the water-table 

fluctuation method.

The area is characterized by well-developed karst (fig. 5), 

which has the ability to move large volumes of water through 

the aquifer quickly by way of a complex network of conduits 

and fractures. The effect of this short residence time in the 

Springfield Plateau aquifer is that a large fraction of the 

recharge from precipitation ends up discharging to springs and 

streams before it can flow through the Ozark confining unit 

into the Ozark aquifer. Whereas the values of recharge used 

in the model are small relative to the Dugan and Peckenpaugh 

(1986) values, the majority of the recharge estimated by 

Dugan and Peckenpaugh (1986) moves through the karst 

system as fracture flow and cannot provide recharge to the 

regional groundwater-flow system. The value of recharge 

used in the model is consistent with the estimated discharge to 

streams and other discharge components of the model.

Table 3. Estimated recharge values of the Springfield Plateau 

aquifer computed from continuous water-level data collected at 

the Longview monitoring well in McDonald County, Missouri.

[ft/d, feet per day; in/yr, inches per year]

Year

Cumulative 

total rise

(inches)

Recharge

(ft/d)

Recharge

(in/yr)

Number of 

observations

1984 23.68 1.95x10-4 0.852 366

1985 25.25 2.08x10-4 .909 365

1989 23.07 1.90x10-4 .831 365

1990 25.43 2.09x10-4 .915 365

1991 21.35 1.75x10-4 .769 365

2001 21.16 1.74x10-4 .762 365

2005 23.71 1.95x10-4 .854 365

2007 24.93 2.05x10-4 .897 351
Description of the Groundwater-Flow Model 31Figure 18. Hydrograph of the Longview monitoring well in McDonald County, Missouri.

150155160165170175180

4 198

5 198

6 198

7 198

8 198

9 198

0 199

1 199

2 199

3 199

4 199

5 199

6 199

7 199

8 199

9 199

0 200

1 200

2 200

3 200

4 200

5 200

6 200

7 200

8 200

ECAF UR S DNAL WOLEBT EEF IN , LEVEL RE AT DEPTH TO W

YEAR

EXPLANATION

Greater than 350 daily observations

MISSOURI

OREGON

COUNTY

MCDONALD

COUNTY

LONGVIEW

MONITORING WELL

MODEL AREA
32 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 19. Areally distributed recharge zones.

EXPLANATION

Recharge zone

Ozark Confining unit (OZCU) - no recharge specifiedRCH1RCH2RCH3

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River Stockton Lake

Fellows

Lake McDaniel Lake

Lake

Springfield

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

Area where recharge was reduced by 32 percent to account for impervious surface
Description of the Groundwater-Flow Model 33

Table 4. Areally distributed recharge zones and values.

[ft/d, feet per day; in/yr, inches per year; OZCU, Ozark confining unit outcrop area (no recharge specified); —, no data; >, greater than]

 Recharge to model with mean annual

precipitation value of 44.97 inches 

Recharge zone 

(fig. 19)

Land-surface slope 

(degrees)

Percentage of total

precipitation (in/yr) (ft/d)

OZCU — 0.00 0.00 0.00

RCH1 0-1 3.00 1.35 3.08x10-4

RCH2 >1-2 2.70 1.21 2.77x10-4

RCH3 >2 2.10 .944 2.16x10-4

RCH1 (reduced by 32 percent to account 

for impervious surface in Springfield) 0-1 2.05 .922 2.11x10-4

RCH2 (reduced by 32 percent to account 

for impervious surface in Springfield) >1-2 1.85 .830 1.89x10-4

RCH3 (reduced by 32 percent to account 

for impervious surface in Springfield) >2 1.44 .645 1.47x10-4

Rivers

Flux to and from river cells is dependent on riverbed 

conductance and the relative altitudes of head in layer 1 

and the river stage. Altitude of the riverbed was obtained 

from DEM data. Nearly all rivers determined to be 

perennial in the low resolution (1:100,000 scale) national 

hydrography dataset (NHD) were included in the model 

(http://nhd.usgs.gov/index.html) (fig. 21). 

Rivers in the area generally flow on gravel, bedrock, or 

both. Both provide little impediment to flow between the river 

and the aquifer. As a result, the streambed conductance was 

calculated based on the vertical hydraulic conductivity of the 

hydrogeologic unit on which the river was flowing. This value 

was adjusted during the calibration process by multiplying 

the streambed conductance by 0.8 for streams flowing on the 

Springfield Plateau aquifer, by 1.3 for streams flowing on the 

Ozark aquifer, and by 10,000 for streams flowing on the Ozark 

confining unit. Streambed conductance ranged from 50 to 

9,750 square feet per day (ft2/d; fig. 22).

To obtain streamflow data for use in calibrating 

the model, on October 10-12, 2006, a seepage run was 

performed by the USGS on the James River Basin upstream 

from the James River at Galena (07052500) streamgage to 

the headwaters of the river (fig. 23, data on file at USGS, 

Rolla, Missouri). It was found that James River and Finley 

Creek generally gain streamflow from the Ozark aquifer 

and generally lose streamflow to the Springfield Plateau 

aquifer. In karst areas, the gain in the river flow is often 

the result of discrete discharge to the river such as spring 

flow into the bottom of the river. Conversely, in karst areas, 

flow can be partly or completely lost in a relatively short 

distance as the river flows on an area of fractured rock or 

flows into a sinkhole. There may also be interbasin transfer 

of groundwater through the karst features. Although several 

flow measurements were made at springs, the 2006 seepage 

run was too coarse to identify discrete recharge/discharge 

points in the river. 

The model simulates flow to or from rivers as diffuse 

flow. The karst nature of the area complicates matching the 

simulated river flows with the observed river flows. Matching 

the difference in observed flow between two observation 

points on the river was problematic. To evaluate discharge to 

rivers in the model, entire basins were chosen rather than a 

specific reach, which assumes that the karst effects would be 

reduced somewhat by using larger contributing flow areas. 

To simplify the karst effects further, it was assumed that the 

statistical 7Q2 values could be used to estimate the base-flow 

discharge to the rivers. 

The 7Q2 was computed at gaged sites with, ideally, 10 

or more years of continuous discharge record. Fourteen river 

basins were chosen as control points to evaluate the simulation 

of the rivers in the model (fig. 21). USGS streamgages exist 

in 10 of the 14 basins. The gages located on the Sac River 

(06918440), Little Sac River (06918740), Turnback Creek 

(06918460), Finley Creek (07052345), and two upstream sites 

on the James River (07050700 and 07052250) were within 

the model boundary (fig. 1, and table 6). The gages located on 
34 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Model recharge Model recharge

Year

Precipitation 

total (in/yr) (in/yr) (ft/d) Year

Precipitation 

total (in/yr) (in/yr) (ft/d)

1907 — 1.136 2.59x10-4 1947 39.62 1.001 2.28x10-4

1908 — 1.136 2.59x10-4 1948 39.45 .996 2.27x10-4

1909 — 1.136 2.59x10-4 1949 50.32 1.271 2.90x10-4

1910 — 1.136 2.59x10-4 1950 37.76 .954 2.18x10-4

1911 — 1.136 2.59x10-4 1951 50.19 1.268 2.89x10-4

1912 — 1.136 2.59x10-4 1952 29.20 .737 1.68x10-4

1913 — 1.136 2.59x10-4 1953 25.21 .637 1.45x10-4

1914 — 1.136 2.59x10-4 1954 37.99 .959 2.19x10-4

1915 46.47 1.174 2.68x10-4 1955 28.61 .723 1.65x10-4

1916 37.80 .955 2.18x10-4 1956 28.72 .725 1.66x10-4

1917 31.71 .801 1.83x10-4 1957 47.90 1.210 2.76x10-4

1918 34.62 .874 2.00x10-4 1957 50.20 1.268 2.89x10-4

1919 38.06 .961 2.19x10-4 1958 44.25 1.118 2.55x10-4

1920 36.89 .932 2.13x10-4 1959 42.99 1.086 2.48x10-4

1921 47.21 1.192 2.72x10-4 1960 33.09 .836 1.91x10-4

1922 36.77 .929 2.12x10-4 1961 46.00 1.162 2.65x10-4

1923 39.53 .998 2.28x10-4 1962 36.85 .931 2.12x10-4

1924 45.13 1.140 2.60x10-4 1963 27.65 .698 1.59x10-4

1925 31.89 .805 1.84x10-4 1964 37.90 .957 2.19x10-4

1926 40.48 1.022 2.33x10-4 1965 44.85 1.133 2.59x10-4

1927 62.45 1.577 3.60x10-4 1966 36.86 .931 2.13x10-4

1928 44.37 1.121 2.56x10-4 1967 43.88 1.108 2.53x10-4

1929 40.15 1.014 2.32x10-4 1968 49.72 1.256 2.87x10-4

1930 30.73 .776 1.77x10-4 1969 30.19 .762 1.74x10-4

1931 38.46 .971 2.22x10-4 1970 43.47 1.098 2.51x10-4

1932 39.35 .994 2.27x10-4 1971 37.53 .948 2.16x10-4

1933 43.82 1.107 2.53x10-4 1972 39.74 1.004 2.29x10-4

1934 36.19 .914 2.09x10-4 1973 58.92 1.488 3.40x10-4

1935 52.79 1.333 3.04x10-4 1974 49.88 1.260 2.88x10-4

1936 30.03 .758 1.73x10-4 1975 45.12 1.139 2.60x10-4

1937 36.16 .913 2.08x10-4 1976 32.74 .827 1.89x10-4

1938 42.36 1.070 2.44x10-4 1977 45.22 1.142 2.61x10-4

1939 35.92 .907 2.07x10-4 1978 43.48 1.098 2.51x10-4

1940 34.22 .864 1.97x10-4 1979 46.08 1.164 2.66x10-4

1941 48.07 1.214 2.77x10-4 1980 27.67 .699 1.60x10-4

1942 47.87 1.209 2.76x10-4 1981 41.97 1.060 2.42x10-4

1943 46.24 1.168 2.67x10-4 1982 47.72 1.205 2.75x10-4

1944 37.17 .939 2.14x10-4 1983 44.13 1.114 2.54x10-4

1945 54.40 1.374 3.14x10-4 1984 48.53 1.226 2.80x10-4

1946 41.51 1.048 2.39x10-4 1985 58.99 1.490 3.40x10-4

Table 5. Annual precipitation totals observed and total model recharge specified in the model area, 1907–2008.

[in/yr, inches per year; ft/d, feet per day; —, no data]
Description of the Groundwater-Flow Model 35

Model recharge

Year

Precipitation 

total (in/yr) (in/yr) (ft/d)

1986 42.19 1.065 2.43x10-4

1987 48.48 1.224 2.80x10-4

1988 44.24 1.117 2.55x10-4

1989 34.07 .860 1.96x10-4

1990 61.29 1.548 3.53x10-4

1991 39.64 1.001 2.29x10-4

1992 48.26 1.219 2.78x10-4

1993 58.05 1.466 3.35x10-4

1994 47.40 1.197 2.73x10-4

1995 42.43 1.072 2.45x10-4

1996 45.96 1.161 2.65x10-4

1997 41.63 1.051 2.40x10-4

1998 48.24 1.218 2.78x10-4

1999 42.87 1.083 2.47x10-4

2000 37.47 .946 2.16x10-4

2001 45.29 1.144 2.61x10-4

2002 37.82 .955 2.18x10-4

2003 42.61 1.076 2.46x10-4

2004 43.23 1.092 2.49x10-4

2005 35.32 .892 2.04x10-4

2006 38.87 .982 2.24x10-4

2007 44.27 1.118 2.55x10-4

2008 60.12 1.518 3.47x10-4

Mean 1971–2000 44.97 1.136 2.59x10-4

Drought (1953) 25.21 .637 1.45x10-4

Table 5. Annual precipitation totals observed and total model 

recharge specified in the model area, 1907–2008.—Continued

[in/yr, inches per year; ft/d, feet per day; —, no data]
36 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 20. Land use/land cover distribution in the model area.

EXPLANATION

ImperviousUrban

Springfield

Cropland and GrasslandForestWetlands and open water

Land use/land cover class

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

Data modified from Missouri Resource

Assessment Partnership, 2005

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS
Description of the Groundwater-Flow Model 37Figure 21. River and spring observation points specified in the model.

Incorporated area

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River Stockton Lake

Fellows

Lake McDaniel Lake

Lake

Springfield

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

3 6

1

7

4

2

9

5

8

35

36

12

11

34

33

30

26 15 22

14 25

16

19

31

17 28

32

29 24 21

23

13 27

10

18

20

1

2 3 4

5

6 7 8 9 10

11

12

13

14

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

River specified in the modelRiver designated perennial in low resolution National Hydrography Dataset

River observation point and identifier (table 6)Spring observation point and identifier (table 7)

5

16
38 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 22. Streambed conductance values for rivers specified in the model and location of lake general-head boundary cells.

LakeIncorporated area

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

50 to less than 2,0002,000 to less than 4,0004,000 to less than 6,0006,000 to less than 8,000greater than 8,000 to 9,750

Streambed conductance,  square foot per day
Description of the Groundwater-Flow Model 39 Figure 23. Discharge measurement locations for the seepage run in the James River Basin, 2006, discharge measurement locations from Imes (1989), and locations of selected wastewater-treatment outfalls.

Incorporated area

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

4

1

0

0

0

0

0.2

0.4

0.4

1.6

0.8

5.3

2.2

5.5

9.3

1.5 2.6 0.2 2.1 0.9

0.5

0.1

2.2

0.1

0.4

0.7 1.1

0.5

0.5

0.2

35.1

37.7

48.3

10.8

53.6

45.7

56.7

41.8

31.2

Springfield

Springfield

Marshfield

Ozark

Nixa

3

12

24

13

12

16

1.9

2.1

6.4

1.1

0.4

1.1

1.1

1.1

1.4

0.2

0.2

0.2

0.2

1.5

2.5

7.6

0.3

0.1

0.1

0.1

0.1

0.7

3.8

4.9

2.5

3.9

0.9 4.8

14.7

0

0

100

Discharge measuredat United States Geological Survey streamgage 07052500

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

7.6

Measurement location (2006)Measurement location from  Imes (1989)Wastewater-treatment outfall

Discharge measurement location  and value, in cubic foot per second

5.5
40 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Bull Creek (07053810), Beaver Creek (07054080), Niangua 

River (06923250), Osage Fork Gasconade River (06927800), 

Pomme de Terre River (06921070), and the downstream 

site on the James River (07052500) were outside the model 

boundary (fig. 1 and table 6). Flow estimates for these gages 

were adjusted by the proportion of basin area within the model 

area. Flow estimates for Swan Creek at the model boundary 

were based on the 7Q2 flow at the gage on Bull Creek 

(07053810) and adjusted to the basin area within the model 

area. Flow estimates for Little Beaver Creek at the model 

boundary were based on the 7Q2 flow at the gage on Beaver 

Creek (07054080) adjusted to the basin area within the model 

area. The 7Q2 flow estimates were reduced by the estimated 

flow of the wastewater outfall in basins that had wastewater 

outfalls with flows greater than 0.8 cubic feet per second, or 

66,000 ft3/d (cubic feet per day; table 6). Wastewater outfall 

flow data were obtained from the Missouri Department of 

Natural Resources (2007). 

Springs

Within the model area, 189 springs have been 

identified by the Missouri Department of Natural Resources 

(2007; fig. 5). Most of the springs have a relatively small 

discharge under base-flow conditions and were not simulated 

in the model. Thirty-six springs were classified by Missouri 

DNR as having a mean discharge of 1 cubic foot per 

second (ft3/s) or greater and were included in the model 

(fig. 21, table 7). Long-term base-flow data for the springs 

in the model area are scarce. Base-flow discharge estimates 

and spring orifice elevation were obtained or inferred 

from data available in Missouri Department of Natural 

Resources (2007), Vineyard and Feder, (1982), and Bullard 

and others (2001). 

Groundwater discharge to springs was simulated 

using the DRN package in MODFLOW (Harbaugh, 2005). 

Groundwater is discharged from the model at a spring if the 

potentiometric head in the aquifer is greater than the spring 

orifice elevation and is discharged at a rate controlled by 

the drain conductance value. Springs in the area generally 

discharge directly from fissures in bedrock or through gravel 

in the spring orifice. This material provides little impediment 

to flow from the aquifer. The drain conductance value was 

specified at 10,000 ft2/d.

General-Head Boundaries

Groundwater flow laterally through the model 

boundaries, vertically through the bottom of the Ozark aquifer, 

and into and out of lakes was simulated using general-head 

boundaries in the model. For general-head boundaries, the 

direction of flow through the boundary is dependent on the 

difference between the potentiometric head in the aquifer and 

the specified reference head, and the flux is regulated by the 

conductance value. General-head boundaries were not varied 

with time in this model because temporal fluctuation in these 

boundaries was unknown.

Lateral Flow at the Model Boundary

A general-head boundary was specified in all three 

model layers around the entire model perimeter to allow 

flow laterally into and out of the model. Specified reference 

head values were derived from measured and inferred water 

levels (Richards and Mugel, 2008; U.S. Geological Survey, 

2007; Gillip and others, 2008, data on file at USGS, Rolla, 

Missouri). The specified conductance value for each cell along 

the boundary is a function of the surface area of the cell face 

in the direction of flow, the horizontal hydraulic conductivity 

in the cell, and the distance between the cell and the referencehead location. Conductance values ranged from 11.5 to 

530.6 ft2/d in layer 1, from 4.56 to 105.0 ft2/d in layer 2, 

and from 59.9 to 1,288 ft2/d in layer 3.

Vertical Flow Through the Bottom of the Ozark Aquifer

Although the flux of water through the bottom of the 

Ozark aquifer was anticipated to be relatively small, the 

direction and magnitude of flow could change as a result 

of additional pumping stress in the future. A general-head 

boundary was specified in layer 3 of the model to simulate 

flow through the bottom of the Ozark aquifer. Reference 

head values in the St. Francois aquifer were specified as a 

constant value of 600 ft. Because there are no wells using 

the St. Francois aquifer in the model area, water levels in 

a monitoring well in the northern part of Oregon County, 

Missouri (fig. 1) were investigated (data on file at USGS, 

Rolla, Missouri). Although this well is located approximately 

100 miles east of Springfield, it is open to the St. Francois 

aquifer and is in a similar structural position relative to the 

center of the Ozark Dome as the study area. The water-level 

altitude tended to fluctuate around 600 ft because of recharge 

to the aquifer. It is assumed that the head in the St. Francois 

aquifer in the model area is similar to the water levels in 

the monitoring well, so 600 ft was chosen as an estimated 

value. The specified conductance value for each cell along 

the boundary is a function of the surface area of the cell face 

in the direction of flow, the vertical hydraulic conductivity of 

the St. Francois confining unit, and the thickness of the St. 

Francois confining unit. The St. Francois confining unit was 

estimated to be 250 ft thick in the model area (Imes, 1989), 

and the vertical hydraulic conductivity was divided into two 

zones with values of 8.75x10-6 and 5.00x10-5 ft/d. These 

values of vertical hydraulic conductivity compare favorably 

with the values of Imes and Emmett (1994) of about 

8.6x10-4 ft/d and Imes (1989) of about 3.8x10-6 ft/d (table 2). 

The calculated conductance values for this model in the two 

zones were 0.035 and 0.200 ft2/d (fig. 24). 
Description of the Groundwater-Flow Model 41

Table 6. Estimated 7-day annual low-flow discharge values for the 2-year recurrence interval at selected sites.[mi2, square miles; ft3/s, cubic feet per second; ft3/d, cubic foot per day; 7Q2, 7-day annual low-flow discharge for the 2-year recurrence interval; —, no data]

Identifier 

(fig. 21)

 Area of 

basin 

contained 

in study 

area

(mi2)

Basin 

area at 

observation point

(mi2)

Station 

number of

streamgage 

used to 

estimate 7Q2

(fig. 1)

River name of 

streamgage 

used to 

estimate 

7Q2

7Q2 at 

streamgage

(ft3/s)

Streamgage 

drainage 

area

(mi2)

Observed 

discharge, 

corrected 

for basin 

area within 

model area

(ft3/s)

Observed 

discharge 

of outfalls 

in basin

(ft3/s)

Observed 

discharge 

outfall

corrected

(ft3/s)

Observed 

discharge 

outfall

corrected

(ft3/d)

A

Simulated 

discharge

(ft3/d)

B

Relative 

percent 

difference

(100|A-B|/

((A+B)/2))

Percent 

error

(100((AB/A))

1 259 259 06918440 Sac River 17.0 257 17.1 1.20 15.9 1,370,824 1,525,195 11 -112 237 237 06918740 Little Sac River 8.10 237 8.10 5.42 2.68 231,552 1,333,779 141 -4763 176 176 06921070 Pomme de Terre River 6.80 276 5.43 — 5.43 469,169 1,104,528 81 -1354 137 142 06923250 Niangua River 20.01 377 11.8 1.08 10.7 927,070 674,453 32 275 111 157 06927800

Osage Fork

Gasconade River

24.0 404 10.6 — 10.6 913,228 637,684 36 30

6 87 163 07054080 Beaver Creek 18.9 298 7.45 — 7.45 643,489 531,189 19 177 55 55 07054080 Beaver Creek 6.08 298 2.61 — 2.61 225,228 278,572 21 -248 107 107 07053810 Bull Creek 3.30 191 2.47 — 2.47 213,738 541,964 87 -1549 99 99 07053810 Bull Creek 3.30 191 2.38 — 2.38 205,297 217,236 6 -6

10 965 973 07052500 James River 111 987 109 49 60.7 5,243,055 3,126,645 51 40

11 181 251 06918460 Turnback Creek 25.0 251 18.0 — 18.0 1,555,899 1,184,626 27 24

12 249 261 07052345 Finley Creek 13.01 261 12.4 1.85 10.6 911,5202 830,3682 9 913 462 462 07052250 James River 58.0 462 58.0 47 11.3 973,7282 1,159,3772 17 -1914 246 246 07050700 James River 8.90 246 8.90 — 8.90 768,9602 646,3632 17 16

Totals 11,998,548 11,155,870 7 7

1Denotes 7Q2 based on 4 years of record2Not included in total because these totals are included in the 07052500 gage
42 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030 Table 7. Base-flow discharge estimates of selected springs. [ft, foot; ft3/s, cubic foot per second; ft3/d, cubic foot per day; SPA, Springfield Plateau aquifer; OZA, Ozark aquifer; —, no data] Identifier (fig. 21) Name Hydrogeologic unit1 Spring altitude1 (ft) Observed discharge (ft3/s) Observed discharge (ft3/d)

A

Simulated

discharge (ft3/d)

B

Relative percent 

difference

(100|A-B|/((A+B)/2))

Percent error 

(100((A-B/A))

1 Broad Creek Spring SPA 1,310 18.70 1,615,680 4,380 199 1002 Rader Spring SPA 1,115 10.50 907,200 117,203 154 873 Dickerson Park Spring SPA 1,170 14.30 1,235,520 34,723 189 974 Sequiota Spring SPA 1,200 .93 80,179 10,823 152 875 Brown Spring (2)

— 1,140 5.12 442,368 20,352 182 95

6 Cavin Cave Spring SPA 1,340 8.03 693,792 3,325 198 1007 Cove Spring

— 1,150 3.20 276,480 0 200 100

8 Spring River Spring #1

— 1,290 2.80 241,920 9,356 185 96

9 Unnamed Spring

— 1,180 5.00 432,000 0 200 100

10 Polk Spring

— 1,280 1.87 161,568 9,836 177 94

11 Ritter Spring (East) SPA 1,125 3.44 297,216 13,329 183 96

12 Fulbright Spring SPA 1,120 3.35 289,440 10,485 186 9613 Todd Spring

— 1,350 3.14 271,296 1,944 197 99

14 Treasure Spring OZA 1,240 3.06 264,384 0 200 10015 Lumlee Spring

— 904 1.63 140,832 71,508 65 49

16 Mountaindale Spring

— 1,473 .82 70,848 10,968 146 85

17 Hart (J.) Spring SPA 1,130 1.94 167,616 13,694 170 9218 Montague

— 1,120 2.71 234,144 0 200 100

19 Jones Spring SPA 1,208 1.20 103,680 11,686 159 8920 Jackson Mill Spring

— 1,000 2.24 193,536 10,382 180 95

21 Chesapeake Spring

— 1,060 .28 24,192 68,751 96 -184

22 Chiles Spring SPA 1,055 2.23 192,499 10,760 179 9423 Blue Spring

— 1,076 1.57 135,648 28,044 131 79

24 Winoka Spring SPA 1,116 .23 19,872 49,374 85 -14825 Hayes Spring SPA 1,110 1.52 131,328 14,313 161 8926 Clear Creek Spring SPA 1,155 1.84 159,391 19,872 156 8827 Otto Lasley Spring

— 1,260 1.80 155,520 1,923 195 99

28 Sthrom Spring

— 1,200 .03 2,592 0 200 100

29 Ward Spring SPA 1,175 1.02 88,128 11,778 153 87
Description of the Groundwater-Flow Model 43

Identifier 

(fig. 21) Name

Hydrogeologic 

unit1

Spring altitude1

(ft)

Observed discharge (ft3/s)

Observed

discharge (ft3/d)

A

Simulated

discharge (ft3/d)

B

Relative percent 

difference

(100|A-B|/((A+B)/2))

Percent error 

(100((A-B/A))

30 Clear Creek Park Spring SPA 1,160 1.53 132,192 16,636 155 8731 Rumfelt Spring — 1,500 1.67 144,288 7,425 180 9532 Trogden Spring SPA 1,175 1.32 114,048 16,242 150 8633 Valley Water Mill Spring — 1,210 1.34 115,776 16,337 151 8634 Ritter Spring (West) SPA 1,125 .56 48,384 16,402 99 6635 Campbell Spring — 1,250 1.29 111,456 0 200 10036 Williams Spring SPA 1,041 1.13 97,632 35,124 94 64

Total 113.34 9,792,645 666,976 174 93

1 Data from Missouri Department of Natural Resources, 2007
44 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 24. Vertical general-head boundary conductance values for model layer 3 simulating flow through the bottom of the Ozark aquifer.

SFCU1

SFCU1

SFCU2

SFCU2

SFCU1

SFCU1

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

0.2000.035

Vertical general-head boundary conductance values in layer 3,  square feet per day
Description of the Groundwater-Flow Model 45

Lakes

Four lakes were included in the model. McDaniel Lake 

and Fellows Lake are impoundments on the Little Sac River 

north of Springfield, Lake Springfield is on the James River 

south of Springfield, and Stockton Lake is on the Sac River in 

the northwestern corner of the model area (fig. 1; table 8). 

Flow into and out of the lakes included in the model were 

simulated with a general-head boundary specified in layer 1 in 

lake cells (fig. 22). Groundwater is discharged from the model 

to the lake if the potentiometric head in the aquifer is greater 

than the reference head in the lake (lake-surface altitude). 

Groundwater is recharged to the model from the lake if the 

potentiometric head in the aquifer is less than the reference 

head in the lake (lake-surface altitude). The rate of flow into 

or out of the boundary is controlled by the conductance value. 

The lakebed conductance value was specified at 100 ft2/d for 

all lakes. The lake-surface altitude was not varied throughout 

the simulation. 

Groundwater Use

All major groundwater users, defined by the Missouri 

DNR as users that are capable of producing 13,369 cubic feet 

[100,000 gallons] or more per day, utilize the Ozark aquifer 

in the model area. Groundwater-use estimates from the Ozark 

aquifer were compiled for 285 wells within the model area 

from Missouri DNR census of Missouri public-supply reports 

(Missouri Department of Natural Resources, 1962–2006), 

Missouri DNR public water-supply database (data on file at 

Missouri Department of Natural Resources, Rolla, Missouri), 

data on file at USGS, Rolla, Missouri, Missouri DNR major 

water-users database (data on file at Missouri Department of 

Natural Resources, Rolla, Missouri), and data directly reported 

by water-supply managers (fig. 25). Data were available from 

multiple sources for the same time period for many wells, and 

often the sources would not agree. All data were aggregated 

for each well to include only the most reliable data to provide 

the most complete groundwater-use record possible. Prior 

to 1962, little groundwater-use data was available for wells 

in the model area. Groundwater-use in a well prior to 1962 

was estimated based on the earliest reported value and was 

computed by reducing this value by 3 percent per year until 

the year the well became operational. Rural groundwater 

use in the model area from the Ozark aquifer was estimated 

using 4,574 domestic Ozark aquifer wells found in the 

Missouri DNR certified well database (Missouri Department 

of Natural Resources, 2007; fig. 25). This database contains 

all certified wells drilled in Missouri after 1986. These wells 

were included in the model to provide a way of estimating 

the effect of domestic groundwater use on the Ozark aquifer. 

However, because it does not include wells drilled prior to 

1986, total distributed domestic use was underestimated. 

Domestic use was not included in the pumpage used in the 

model prior to 1987.

Groundwater use is listed by stress period for the Ozark 

aquifer in table 9 and increases from 529 ft3/d in 1907 to 

1,093,268 ft3/d in 1962 to 2,693,423 ft3/d in 1987 to 

4,330,177 ft3/d in 2006. Groundwater users (rural domestic 

use wells omitted) and their pumpage rates in 2006 are shown 

in figure 26. Groundwater use in 2006 from the 4,574 rural 

domestic wells in the Ozark aquifer was estimated at 

53.5 ft3/d (400 gallons per day [gal/d]) per well for a total rural 

use of 245,833 ft3/d (1,838,000 gal/d). Rural domestic use 

represents 5.7 percent of the total 4,330,177 ft3/d 

(32,389,721 gal/d) groundwater use for 2006. Total rural 

domestic use in the 4,574 wells was estimated at 123,519 ft3/d 

(923,986 gal/d) in 1987. The 1987 estimated value of rural 

Table 8. Lakes specified in layer 1 of the model.

[mi2, square miles; ft, foot; NGVD, National Geodetic Vertical Datum]

Name Year constructed1

Area contained

in model

(mi2)

River impounded

Lake-surface

altitude2

(ft above NGVD 1929)

Water use

McDaniel Lake 1929 0.65 Little Sac River 1,123 drinking water

Fellows Lake 1955 1.43 Little Sac River 1,261 drinking water

Lake Springfield 1956 1.04 James River 1,142 cooling water

Stockton Lake 1969 6.28 Sac River 867 drinking water

1

 Missouri Department of Natural Resources, 2008

2

 Data from: U.S. Geological Survey 1:24,000 scale topographic maps
46 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 25. Pumping wells specified in the model area.

Incorporated area

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

Data modified from MissouriDepartment of Natural Resources, 2007

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

Domestic wellMajor water-user /  Public-supply wellProposed future water-supply well included in all model  predictive simulationsProposed future well included in model predictive scenarios 6 and 7
Model Calibration 47

domestic use represents 4.6 percent of the total groundwater 

use of 2,693,423 ft3/d (20,148,203 gal/d) in 1987 (table 9). To 

simulate rural growth during the period from 1987 to 2006 

the water use was increased linearly from the 1987 value to 

the 2006 value. 

Groundwater use from the Springfield Plateau aquifer 

was not included in the model. The productivity of the 

Springfield Plateau aquifer is only sufficient for domestic 

wells. The spatial distribution and number of wells completed 

in the Springfield Plateau aquifer is unknown in the model 

area. In addition, wells drilled prior to 1987 that are open to 

the Springfield Plateau aquifer often are also open to the Ozark 

aquifer. After 1987, wells completed in the general model area 

were required to be cased through the Ozark confining unit 

(Jim Vandike, Missouri Department of Natural Resources, oral 

commun., 2007). 

Model Calibration

The groundwater model was calibrated by adjusting 

model parameters to make simulated head and discharge 

results match water-level altitude observations and 

groundwater flow to rivers and springs within an acceptable 

level of accuracy (Konikow, 1978). Parameters adjusted 

during the calibration process include horizontal and 

vertical hydraulic conductivity, specific storage, specific 

yield, riverbed conductance, lakebed conductance, spring 

conductance, and recharge rates. After each change in these 

parameters, the simulation was run and simulated head 

was compared to observed groundwater levels. Layers 

were divided into zones to allow hydraulic properties to 

vary spatially. When groups of simulated values were too 

large or too small relative to the observed values, a zone 

would be created encompassing those groups of observed 

values based on geologic criteria or professional judgment. 

Because changes to the hydraulic properties of a zone have 

the largest effect on simulated values closest to the zone, 

adjustment of hydraulic properties of the zone would allow 

for better agreement between the simulated and observed 

values in the zone.

Hydraulic Property Estimation

The hydraulic properties in this model were initially 

estimated based on the properties of rocks with similar 

hydraulic characteristics, previously published model values, 

measured values, and values calculated from other hydrologic 

data (table 2). Hydraulic properties used in calibration include 

the horizontal and vertical hydraulic conductivity, specific 

storage, and specific yield (table 10). Hydraulic property zones 

were created within the model, and values within the zones 

were adjusted to minimize the difference between simulated 

and observed values. 

Horizontal Hydraulic Conductivity

Hydraulic conductivity is a property that describes the 

ease with which groundwater can move through the aquifer 

material (Freeze and Cherry, 1979). Measured horizontal 

hydraulic conductivity data are scarce in the model area. 

Vandike and Sherman (1994) calculated a mean horizontal 

hydraulic conductivity of 2.11 ft/d for the Ozark aquifer from 

an aquifer test conducted in Greene County. Transmissivity, 

which was converted to horizontal hydraulic conductivity by 

dividing by aquifer thickness, can be estimated from specificcapacity well test data using the techniques of Thomasson and 

others (1960) and Todd (1959). To estimate transmissivity 

using specific capacity data it was assumed that the aquifer 

was confined and isotropic, that Darcy’s law for flow was 

applicable, that permeable zones were uniformly distributed 

vertically through the aquifer, and that the well was 

100 percent efficient and fully penetrated the aquifer. Most 

of the wells in the model area that have specific capacity data 

do not fully penetrate the aquifer so a correction described in 

Todd (1959) was applied. 

Estimates of Ozark aquifer transmissivity were computed 

from specific-capacity data for 70 wells in the model area. 

Hydraulic conductivity ranged from 0.20 to 8.73 ft/d, and 

was computed by dividing the transmissivity by the aquifer 

thickness (fig. 27; table 11). Horizontal hydraulic conductivity 

for the Springfield Plateau aquifer and the Ozark confining 

unit were estimated from published typical ranges for similar 
48 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030 Table 9. Stress period length, pumping rates, and number of water-level observations used in the model. [variable, pumping rate varies according to the future scenario tested; ft3/d, cubic foot per day; ft3/s, cubic foot per second; USGS, U. S. Geological Survey; DNR, Missouri Department of Natural Resources; layer 1, Springfield Plateau aquifer and shallow Ozark aquifer observations; layer 3, deep Ozark aquifer observations] Number of water-level altitude observations Stress period Year Length of stress period (days) Groundwater-pumping rate USGS1 DNR2 Total (ft3/d) (ft3/s) Layer 1 Layer 3 Layer 1 Layer 3

1 Steady State 0 0.00 42 6 0 34 822 1907 365 529 .01 0 0 0 0 03 1908 366 545 .01 0 0 0 0 04 1909 365 562 .01 0 0 0 0 05 1910 365 579 .01 0 0 0 0 06 1911 365 2,967 .03 0 0 0 0 07 1912 366 3,057 .04 0 0 0 0 08 1913 365 3,150 .04 0 0 0 0 09 1914 365 3,246 .04 0 0 0 0 0

10 1915 365 9,443 .1 0 0 0 0 0

11 1916 366 9,730 .1 0 0 0 0 0

12 1917 365 10,026 .1 0 0 0 0 013 1918 365 10,332 .1 0 0 0 0 014 1919 365 10,646 .1 0 0 0 0 015 1920 366 10,971 .1 0 0 0 0 016 1921 365 11,305 .1 0 0 0 0 017 1922 365 11,649 .1 0 0 0 0 018 1923 365 12,004 .1 0 0 0 0 019 1924 366 12,369 .1 0 0 0 0 020 1925 365 14,107 .2 0 0 0 0 021 1926 365 16,058 .2 0 0 0 0 022 1927 365 19,922 .2 0 0 0 0 023 1928 366 20,528 .2 0 0 0 0 024 1929 365 21,153 .2 0 0 0 0 025 1930 365 35,022 .4 0 0 0 0 026 1931 365 36,028 .4 0 0 0 0 027 1932 366 38,743 .4 0 0 0 0 028 1933 365 39,862 .5 0 0 0 0 029 1934 365 41,015 .5 0 0 0 0 0
Model Calibration 49

Number of water-level altitude observations

Stress period Year

Length of 

stress period 

(days)

Groundwater-pumping rate USGS1 DNR2

Total (ft3/d) (ft3/s) Layer 1 Layer 3 Layer 1 Layer 3

30 1935 365 42,204 .5 0 0 0 0 031 1936 366 43,428 .5 0 0 0 0 032 1937 365 48,255 .6 0 0 0 0 033 1938 365 52,763 .6 0 0 0 0 034 1939 365 54,309 .6 0 0 0 0 035 1940 366 55,902 .6 0 0 0 0 036 1941 365 98,519 1.1 0 0 0 0 037 1942 365 109,870 1.3 0 0 0 0 038 1943 365 113,156 1.3 0 0 0 0 039 1944 366 116,541 1.3 0 0 0 0 040 1945 365 120,029 1.4 0 0 0 0 041 1946 365 124,508 1.4 0 0 0 0 042 1947 365 135,617 1.6 0 0 0 0 043 1948 366 141,494 1.6 0 0 0 0 044 1949 365 148,223 1.7 0 0 0 0 045 1950 365 167,162 1.9 0 0 0 0 046 1951 365 187,116 2.2 0 0 0 0 047 1952 366 206,598 2.4 0 0 0 0 048 1953 365 237,859 2.8 0 0 0 0 049 1954 365 376,952 4.4 0 0 0 0 050 1955 365 363,322 4.2 0 0 0 0 051 1956 366 380,455 4.4 0 0 0 0 052 1957 365 394,114 4.6 0 0 0 0 053 1958 365 544,878 6.3 0 0 0 0 054 1959 365 583,448 6.8 0 0 0 0 055 1960 366 600,257 6.9 0 0 0 0 056 1961 365 1,076,156 12.5 0 0 0 0 057 1962 365 1,093,268 12.7 0 0 0 0 058 1963 365 1,191,196 13.8 0 0 0 0 059 1964 366 1,234,046 14.3 0 0 0 0 060 1965 365 1,203,546 13.9 0 0 0 0 061 1966 365 1,270,353 14.7 0 0 0 0 0
50 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030 Number of water-level altitude observations Stress period Year Length of stress period (days) Groundwater-pumping rate USGS1 DNR2 Total (ft3/d) (ft3/s) Layer 1 Layer 3 Layer 1 Layer 3 62 1967 365 1,256,259 14.5 0 0 0 0 0 63 1968 366 1,383,728 16.0 0 0 0 0 0 64 1969 365 1,433,336 16.6 0 0 0 0 0 65 1970 365 1,527,494 17.7 0 0 0 0 0 66 1971 365 1,625,549 18.8 0 0 0 0 0 67 1972 366 1,797,899 20.8 0 0 0 0 0 68 1973 365 1,840,615 21.3 0 0 0 0 0 69 1974 365 2,021,967 23.4 0 0 0 0 0 70 1975 365 1,883,362 21.8 0 0 0 0 0 71 1976 366 2,329,281 27.0 0 0 0 0 0 72 1977 365 1,969,073 22.8 0 0 0 0 0 73 1978 365 2,022,072 23.4 0 0 0 0 0 74 1979 365 2,340,508 27.1 0 0 0 0 0 75 1980 366 2,720,889 31.5 0 0 0 0 0 76 1981 365 2,314,257 26.8 0 0 0 0 0 77 1982 365 2,308,995 26.7 0 0 0 0 0 78 1983 365 2,330,251 27.0 0 0 0 0 0 79 1984 366 2,233,418 25.8 0 0 0 0 0 80 1985 365 2,114,842 24.5 0 0 0 0 0 81 1986 365 2,125,795 24.6 0 0 0 0 0 82 1987 365 2,693,423 31.2 9 48 1 10 68 83 1988 366 2,897,164 33.5 0 0 2 55 57 84 1989 365 2,941,884 34.0 81 2 3 61 147 85 1990 365 3,230,375 37.4 11 1 1 57 70 86 1991 365 3,296,308 38.2 16 0 14 55 85

87 1992 366 3,178,253 36.8 21 2 20 86 12988 1993 365 2,692,654 31.2 13 24 5 70 11289 1994 365 2,942,806 34.1 0 1 47 66 11490 1995 365 3,050,711 35.3 1 2 27 68 9891 1996 366 3,539,861 41.0 9 35 23 43 110

Table 9. Stress period length, pumping rates, and number of water-level observations used in the model.—Continued[variable, pumping rate varies according to the future scenario tested; ft3/d, cubic foot per day; ft3/s, cubic foot per second; USGS, U. S. Geological Survey; DNR, Missouri Department of Natural Resources; layer 1, Springfield Plateau aquifer and shallow Ozark aquifer observations; layer 3, deep Ozark aquifer observations]
Model Calibration 51

Number of water-level altitude observations

Stress period Year

Length of 

stress period 

(days)

Groundwater-pumping rate USGS1 DNR2

Total (ft3/d) (ft3/s) Layer 1 Layer 3 Layer 1 Layer 3

92 1997 365 3,351,881 38.8 1 1 27 41 7093 1998 365 3,681,955 42.6 15 8 16 55 9494 1999 365 3,751,821 43.4 0 1 39 63 10395 2000 366 3,968,491 45.9 1 2 35 73 11196 2001 365 3,716,189 43.0 1 2 41 63 10797 2002 365 3,866,498 44.8 0 19 48 62 12998 2003 365 3,966,025 45.9 0 10 51 52 11399 2004 366 3,906,372 45.2 0 7 62 46 115

100 2005 365 4,176,776 48.3 0 16 35 46 97101 2006 365 4,330,177 50.1 15 132 0 0 147

102-125 2007-2030 365 (366 leap years) variable variable 0 0 0 0 0

1 Data from USGS national water information system database (U.S. Geological Survey, 2007)2 Data from Missouri Department of Natural Resources, 2007
52 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 26. Groundwater use from wells in the Ozark aquifer in 2006 (domestic-supply wells omitted for clarity).

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

less than 10,000greater than 10,000 to 100,000greater than 100,000 to 500,000greater than 500,000 to 1,000,000greater than 1,000,000 

Water use, in gallons per day

Incorporated area
Model Calibration 53

rocks (Freeze and Cherry, 1979) and previously published 

model values. These horizontal hydraulic conductivity 

estimates were used as initial values and were zoned and 

adjusted manually during the calibration process to minimize 

the difference between simulated and observed values 

(figs. 28, 29, and 30). Specific-capacity data, aquifer-test data, 

and other geologic evidence indicate that areas of markedly 

differing horizontal hydraulic conductivity exists throughout 

the Ozark aquifer. It is speculated that these differences are 

a result of karst features such as solution-enlarged fractures 

or solution-enlarged bedding planes (Jim Vandike, Missouri 

Department of Natural Resources, oral commun., 2010) in 

the Ozark aquifer. Small zones were initially placed around 

some wells in layer 3 of the model where specific capacity 

data indicated large changes in hydraulic conductivity might 

exist. However, they were subsequently removed because their 

presence had little effect on the simulated head distribution 

in the model and the location, extent, and orientation of those 

zones was uncertain. Final horizontal hydraulic conductivity 

values used in this model can be found in table 10.

Vertical Hydraulic Conductivity

The ability of a hydrogeologic unit to conduct 

groundwater flow horizontally can differ considerably from its 

ability to conduct flow vertically. Horizontal flow is likely to be 

the predominant component of flow in the hydrogeologic units 

in the model area (Czarnecki and others, 2009). In the model, 

the ratio of vertical to horizontal hydraulic conductivity is used 

to account for vertical anisotropy. No measurements of vertical 

anisotropy for any of the hydrogeologic units have been made 

in the model area. Initial estimates of the vertical to horizontal 

hydraulic conductivity ratio were obtained from Czarnecki and 

others (2009), and these estimates ranged from 1:1 to 1:50 for 

the hydrogeologic units that were nearest to this model area. 

Final vertical hydraulic conductivity values after adjustment 

through model calibration are presented in table 10.

Table 10. Hydraulic property values specified in the calibrated model.

[ft/d, feet per day; 1/ft, per foot]

Hydraulic conductivity

Zone name

Horizontal

(ft/d)

Vertical

(ft/d)

Specific storage

(1/ft)

Specific yield

(dimensionless) Figure number

Springfield Plateau aquifer

SPA1 2.50 0.050 1.00x10-5 0.003 28

SPA2 2.20 .073 1.00x10-5 .003 28

SPA3 5.00 .167 1.00x10-5 .003 28

Ozark confining unit

OZCU1 1.00x10-6 2.00x10-7 5.00x10-6 .100 29

OZCU2 2.80x10-5 5.60x10-6 5.00x10-6 .100 29

OZCU3 7.50x10-5 1.50x10-5 5.00x10-6 .100 29

Ozark aquifer

OZA1 1.30 .130 1.00x10-6 .003 30

OZA2 .35 .070 5.00x10-4 .003 30

OZA3 .35 .035 5.00x10-6 .003 30

OZA4 1.50 .150 1.00x10-4 .003 30

OZA5 .25 .050 5.00x10-5 .003 30

OZA6 .30 .030 1.00x10-7 .003 30

OZA7 .80 .080 1.00x10-8 .003 30

OZA8 3.00 .300 1.00x10-5 .003 30
54 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 27. Horizontal hydraulic conductivity in the Ozark aquifer estimated from specific-capacity data of wells.

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River

7

2

8

6

9

3

5

1

4

14

40 17

27 55

26 44 50 18 39 32

31

34

30

38 60

70

36

61 52

41 54

64 66

51 49

65 25 10 69 53

23 68 28 21 12

13

46

56 11 58

59

37 29 24

22 15

16 67 63 47 48

57

42

45

19

35

20

62

43 GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

0.2 - 1.0greater than 1.0 - 3.0greater than 3.0

Hydraulic conductivity (in feet  per day) and well number (table 11)

571733

Incorporated area
Model Calibration 55

Table 11. Hydraulic conductivity estimated from specific-capacity data for selected wells in the model area.[Qp is the discharge of the well that partially penetrates the aquifer; sw is drawdown in the pumping well; bp is the depth of well penetration into the aquifer; b is the aquifer thickness; Rw is the radius of the well; R is the radius of influence of the pumping well; Qc is the discharge of the well if the well had completely penetrated the aquifer; T is transmissivity; K is hydraulic conductivity; ft3/d, cubic foot per day; ft, foot; ft2/d, square foot per day; ft/d, foot per day]

Well number 

from figure 

27

Q

p

(ft3/d)

s

w

(ft) 

b

p

(ft)

b 

(ft)

R

w

(ft)

R 

(ft)

Q

p/sw

(ft2/d)

Q

p/Qc

(dimensionless) Qc/sw (ft2/d) T (ft2/d) K (ft/d)

1 17,326 110 896 1,619 0.25 250 158 0.53 300 330 0.202 69,305 470 815 1,299 .42 417 147 .62 236 260 .203 105,882 550 1,035 1,243 .42 417 193 .84 230 253 .204 105,882 460 1,215 1,326 .50 500 230 .93 248 272 .215 28,877 157 935 1,643 .33 333 184 .55 334 368 .226 192,513 1,200 750 1,237 .50 500 160 .61 263 289 .237 48,128 169 1,287 1,345 .33 333 285 .97 293 323 .248 48,128 145 1,310 1,549 .33 333 332 .84 394 433 .289 4,813 50 360 1,350 .25 250 96 .26 372 409 .30

10 65,455 242 839 1,238 .33 333 270 .67 404 444 .36

11 7,701 75 290 1,220 .25 250 103 .23 437 481 .39

12 72,193 120 1,600 1,696 .25 250 602 .95 632 696 .4113 202,139 462 1,108 1,339 .58 583 438 .84 522 575 .4314 30,802 143 519 1,500 .25 250 215 .33 655 720 .4815 84,128 170 1,088 1,195 .67 667 495 .93 533 587 .4916 121,091 240 1,061 1,198 .67 667 505 .90 559 615 .5117 32,727 100 695 1,501 .25 250 327 .44 745 819 .5518 13,476 55 463 1,294 .42 417 245 .36 679 747 .5819 11,551 70 300 1,061 .25 250 165 .28 588 647 .6120 130,139 230 1,023 1,197 .67 667 566 .87 650 715 .6021 71,230 167 765 1,328 .33 333 427 .56 756 831 .6322 145,733 205 1,099 1,197 .67 667 711 .94 760 836 .7023 244,492 320 1,178 1,264 .50 500 764 .95 807 887 .7024 192,513 260 1,074 1,390 .50 500 740 .78 954 1,049 .7525 1,925 10 271 1,266 .25 250 193 .21 907 998 .7926 77,005 110 899 1,299 .33 333 700 .68 1,025 1,127 .8727 17,326 55 388 1,376 .25 250 315 .27 1,157 1,272 .9228 115,508 180 760 1,328 .42 417 642 .57 1,129 1,242 .9429 404,278 333 1,256 1,256 .75 750 1,214 1.00 1,214 1,335 1.06
56 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030 Table 11. Hydraulic conductivity estimated from specific capacity data for selected wells in the model area.—Continued [Qp is the discharge of the well that partially penetrates the aquifer; sw is drawdown in the pumping well; bp is the depth of well penetration into the aquifer; b is the aquifer thickness; Rw is the radius of the well; R is the radius of influence of the pumping well; Qc is the discharge of the well if the well had completely penetrated the aquifer; T is transmissivity; K is hydraulic conductivity; ft3/d, cubic foot per day; ft, foot; ft2/d, square foot per day; ft/d, foot per day] Well number from figure 27

Qp

(ft3/d)

sw

(ft) 

bp

(ft)

b 

(ft)

Rw

(ft)

R 

(ft)

Qp/sw

(ft2/d)

Qp/Qc

(dimensionless)

Qc/sw

(ft2/d)

T 

(ft2/d)

K 

(ft/d)

30 38,503 48 776 1,285 0.42 417 802 0.60 1,335 1,468 1.1431 67,380 60 1,043 1,553 .33 333 1,123 .66 1,711 1,883 1.2132 38,503 40 821 1,549 .33 333 963 .51 1,875 2,063 1.3333 218,888 160 1,113 1,197 .67 667 1,368 .95 1,443 1,588 1.3334 103,957 85 925 1,342 .42 417 1,223 .69 1,783 1,961 1.4635 53,904 50 798 1,206 .33 333 1,078 .65 1,649 1,813 1.5036 48,128 40 879 1,327 .33 333 1,203 .65 1,847 2,031 1.5337 231,016 180 891 1,399 .33 333 1,283 .62 2,057 2,263 1.6238 44,663 74 364 1,244 .33 333 604 .29 2,057 2,263 1.8239 105,882 76 800 1,232 .50 500 1,393 .65 2,129 2,342 1.9040 32,920 21 887 1,600 .33 333 1,568 .54 2,923 3,215 2.0141 80,856 55 815 1,300 .42 417 1,470 .62 2,358 2,594 1.9942 28,877 23 675 1,242 .33 333 1,256 .53 2,350 2,585 2.0843 113,583 59 976 1,303 .50 500 1,925 .75 2,554 2,809 2.1644 76,043 37 913 1,306 .33 333 2,055 .69 2,978 3,276 2.5145 61,604 33 790 1,237 .33 333 1,867 .63 2,966 3,262 2.6446 205,219 71 1,217 1,347 .50 500 2,890 .92 3,156 3,472 2.5847 192,513 84 950 1,091 .42 417 2,292 .88 2,603 2,863 2.6248 225,241 127 740 1,328 .50 500 1,774 .56 3,168 3,485 2.6249 154,011 50 1,236 1,319 .67 667 3,080 .95 3,228 3,551 2.6950 100,107 50 775 1,362 .42 417 2,002 .56 3,549 3,904 2.8751 178,075 55 1,233 1,301 .67 667 3,238 .97 3,352 3,687 2.8352 102,032 35 1,072 1,283 .42 417 2,915 .84 3,470 3,818 2.9753 57,754 25 765 1,249 .33 333 2,310 .60 3,833 4,217 3.3754 80,856 28 915 1,301 .42 417 2,888 .70 4,118 4,530 3.4855 50,053 20 787 1,495 .33 333 2,503 .51 4,898 5,388 3.6056 29,840 10 873 1,334 .25 250 2,984 .63 4,705 5,175 3.8857 115,508 30 995 1,306 .42 417 3,850 .76 5,053 5,559 4.2658 86,631 26 855 1,319 .83 833 3,332 .67 4,987 5,486 4.1659 173,262 37 1,069 1,214 .50 500 4,683 .89 5,247 5,772 4.75
Model Calibration 57

Well number 

from figure 

27

Q

p

(ft3/d)

s

w

(ft) 

b

p

(ft)

b 

(ft)

R

w

(ft)

R 

(ft)

Q

p/sw

(ft2/d)

Q

p/Qc

(dimensionless) Qc/sw (ft2/d) T (ft2/d) K (ft/d)

60 103,957 25 876 1,327 .42 417 4,158 .66 6,333 6,966 5.2561 57,754 9 1,220 1,298 .33 333 6,417 .95 6,743 7,417 5.7162 115,508 24 850 1,283 .42 417 4,813 .66 7,292 8,021 6.2563 28,877 10 470 1,116 .33 333 2,888 .42 6,892 7,581 6.7964 117,433 21 920 1,298 .42 417 5,592 .71 7,913 8,704 6.7065 4,813 2 400 1,620 .25 250 2,406 .24 10,187 11,205 6.9266 52,941 10 815 1,252 .33 333 5,294 .64 8,246 9,070 7.2567 11,551 20 85 1,183 .25 250 578 .08 7,126 7,838 6.6368 63,529 10 935 1,571 .33 333 6,353 .58 10,994 12,094 7.7069 154,011 25 779 1,233 .42 417 6,160 .63 9,777 10,755 8.7270 231,016 35 830 1,359 .50 500 6,600 .61 10,781 11,859 8.73
58 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 28. Horizontal and vertical hydraulic conductivity, specific storage, and specific yield zones for the Springfield Plateau aquifer used in the model to calculate composite hydraulic properties.

SPA3

SPA1

SPA2

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS
Model Calibration 59 Figure 29. Horizontal and vertical hydraulic conductivity, specific storage, and specific yield zones for the Ozark confining unit used in the model to calculate composite hydraulic properties.

OZCU1

OZCU2

OZCU3

OZCU3

OZCU1

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS
60 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 30. Horizontal and vertical hydraulic conductivity, specific storage, and specific yield zones for the Ozark aquifer used in the model to calculate composite hydraulic properties.

OZA4

OZA5

OZA2

OZA3

OZA7

OZA1

OZA8

OZA6

OZA4

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS
Model Calibration 61

Specific Storage

Specific storage for a saturated confined aquifer is 

the volume of water released from storage per unit decline 

in head (Freeze and Cherry, 1979). It describes the water 

released from storage because of expansion of the water or 

compaction of the aquifer material and not actual drainage of 

the aquifer. Vandike and Sherman (1994) computed a storage 

coefficient in the Ozark aquifer of 1.6x10-4 from an aquifer 

test in the Fulbright Spring area of Greene County (fig. 2). 

This storage coefficient is equivalent to a specific storage of 

1.33x10-7 per ft for an average aquifer thickness of 1,200 ft. 

This value for the Ozark aquifer and values from Imes (1989) 

and Czarnecki and others (2009) were used as initial estimates 

in this model. Final values of specific storage obtained after 

adjustment during the calibration process are presented in 

table 10.

Specific Yield

Specific yield is the measure of the volume fraction of the 

aquifer of water that will drain by gravity from an unconfined 

aquifer (Freeze and Cherry, 1979). Values of specific yield 

in this model were estimated based on values used in Imes 

(1989) and Czarnecki and others (2009) and adjusted during 

the calibration process. Final specific yield values used in this 

model are presented in table 10.

Calibrated Hydraulic Properties Compared To 

Previously Published Values

Hydraulic properties specified for the hydrogeologic units 

in the calibrated model (table 10) are compared to previously 

published estimates (table 2) in the following sections. In 

general, most of the hydraulic properties specified in the 

calibrated model fit into the range of previously published 

values for the hydrogeologic units in the model area. 

Springfield Plateau Aquifer Calibrated Hydraulic 

Properties

In this model, the horizontal hydraulic conductivity of 

the Springfield Plateau aquifer ranged between 2.20 and 

5.00 ft/d (table 10), and fit within the range of values used 

in other groundwater models in the region (table 2). Freeze 

and Cherry (1979) provide estimates of horizontal hydraulic 

conductivity for limestone and dolomite that range from about 

0.0005 to 0.60 ft/d, and for karst limestone that range from 

about 0.1 to 2,000 ft/d. For the Springfield Plateau aquifer, 

Imes (1989) used values of horizontal hydraulic conductivity 

of 4.3 to 43 ft/d in the Springfield, Missouri area, and Imes and 

Emmett (1994) specified 21.6 ft/d for the part of their model 

that overlaps this model area. Reed and Czarnecki (2006) used 

values of horizontal hydraulic conductivity ranging between 

1.3 to 35 ft/d in northeastern Oklahoma, and Czarnecki and 

others (2009) used 0.89 to 35 ft/d in their model. In this model, 

the ratio of the vertical to horizontal hydraulic conductivity 

of the Springfield Plateau aquifer ranged from 1:30 to 1:50 

and the vertical hydraulic conductivity ranged from 0.050 to 

0.167 ft/d. Reed and Czarnecki (2006) used values of vertical 

hydraulic conductivity between 2.6x10-2 and 7.0x10-1 ft/d, 

and Czarnecki and others (2009) specified vertical hydraulic 

conductivity to be between 2.97x10-4 and 1.00 ft/d in their 

groundwater model (table 2). 

Specific yield was specified as 0.003 for the Springfield 

Plateau aquifer in this model (table 10). The usual range of 

specific yield for unconfined aquifers is from 0.01 to 0.30 

(Freeze and Cherry, 1979). Imes (1989) specified a specific 

yield value of 2.00x10-2 in the Springfield Plateau aquifer. 

Czarnecki and others (2009) report mean values of specific 

yield from hydraulic tests in carbonate aquifers in Poland and 

Spain that range between 6.00x10-5 and 5.79x10-3. Specific 

yield in Czarnecki and others (2009) ranged from 1.00x10-2 to 

1.00x10-1. Specific yield was specified as 2.00x10-1 in Reed 

and Czarnecki (2006) (table 2).

Ozark Confining Unit Calibrated Hydraulic Properties

The horizontal hydraulic conductivity of the Ozark 

confining unit in this model ranged between 1.00x10-6 to 

7.50x10-5 ft/d (table 10). Horizontal hydraulic conductivity 

ranged between 1.0x10-5 to 4.0x10-5 in Czarnecki and others 

(2009). In this model, the vertical to horizontal hydraulic 

conductivity ratio was 1:5 in the Ozark confining unit, and the 

vertical hydraulic conductivity ranged between 2.00x10-7 to 

1.50x10-5 ft/d (table 10). Emmett and others (1978) estimated 

the vertical hydraulic conductivity for the Ozark confining 

unit to be about 8.6x10-5 ft/d. Imes (1989) specified values of 

vertical hydraulic conductivity of 7.8x10-6 and 9.5x10-6 ft/d 

for the Ozark confining unit near Springfield, Missouri. 

Christenson and others (1994) used a leakance value between 

4.3x10-8 and 7.7x10-8 per day (d-1) for the Ozark confining 

unit in Ottawa County, Oklahoma. Imes and Emmett (1994) 

used vertical hydraulic conductivity values between 1.7x10-3

and 4.3x10-3 ft/d and a leakance value between 5.2x10-5 and 

1.7x10-4 d-1 to simulate flow through the Ozark confining unit. 

Czarnecki and others (2009) used values of vertical hydraulic 

conductivity between 2.0x10-7 and 2.45x10-5 ft/d for the Ozark 

confining unit in their groundwater model (table 2). 

Specific storage was specified as 5.00x10-6 per foot 

and specific yield was specified as 0.100 in this model for 

the Ozark confining unit (table 10). Specific storage in 

Czarnecki and others (2009) was specified as 5.0x10-6 per 

foot and specific yield was specified as 1.00x10-1 in their 

model (table 2). 

Ozark Aquifer Calibrated Hydraulic Properties

The horizontal hydraulic conductivity of the Ozark 

aquifer in this model ranged from 0.25 to 3.00 ft/d (table 10), 

and was within the range of values specified in other area 

groundwater flow models and aquifer test results in the region 

(table 2). Emmett and others (1978) estimated a transmissivity 

value of 3,974 square feet per day (ft2/d) from two short-term 
62 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

pump tests, which the authors state was an anomalously large 

local value. However, the authors subsequently used a flownet analysis of Lohman (1972) and determined a value of 

670 ft2/d. Vandike and Sherman (1994) performed a 

64-day aquifer test in the Fulbright Spring area (fig. 2) of 

Greene County using a fully penetrating Ozark aquifer well 

pumping at a mean rate of 2,382 gal/min and calculated 

a mean horizontal hydraulic conductivity of 2.11 ft/d for 

the Ozark aquifer in that area. Imes (1989) specified the 

horizontal hydraulic conductivity of the Ozark aquifer to be 

between about 0.7 and 2.6 ft/d in the Springfield, Missouri 

area. Imes and Emmett (1994) estimated the horizontal 

hydraulic conductivity in their model to be between about 

6.91 ft/d and 11.23 ft/d for the area of the model covered 

by this report. Czarnecki and others (2009) used horizontal 

hydraulic conductivity values between about 0.10 and 

5.00 ft/d for their groundwater model (table 2). The vertical 

to horizontal hydraulic conductivity ratio for the Ozark 

aquifer in this model ranged from 1:5 to 1:10, and the vertical 

hydraulic conductivity ranged from 0.030 and 0.300 ft/d 

(table 10). Czarnecki and others (2009) used vertical hydraulic 

conductivity values between about 5.00x10-3 and 1.81 ft/d for 

their groundwater model (table 2).

The specific storage values of the Ozark aquifer in this 

model ranged from 1.00x10-8 to 5.00x10-4 per ft (table 10), 

and was similar to values specified in previous groundwaterflow models and aquifer test results in the region (table 2). 

Imes (1989) specified the storage coefficient in the Ozark 

aquifer to be 1.0x10-4, which is equivalent to a specific storage 

value of 8.3x10-8 per ft for a mean aquifer thickness of 

1,200 ft. Specific storage of 1.33x10-7 per ft, using an aquifer 

thickness of 1,200 ft, was computed from data collected 

by Vandike and Sherman (1994). Czarnecki and others 

(2009) specified specific storage ranging from 1.00x10-7 to 

3.97x10-5 per ft in the Ozark aquifer (table 2). Specific yield 

in this model was specified as 0.003 for the Ozark aquifer 

(table 10). This value is similar to values specified in other 

groundwater-flow models in the region (table 2). Imes (1989) 

specified a range of specific yield values from 1.00x10-3 to 

2.00x10-2 in the Ozark aquifer. Czarnecki and others (2009) 

specified specific yield values ranging from about 3.56x10-4 to 

7.50x10-2 for the Ozark aquifer.

Water-Level Observations

Water-level data from wells were collected during 

2006–07 to provide a groundwater model calibration data set. 

These data were collected from field measurements by USGS 

personnel, from the Missouri DNR groundwater-monitoring 

network, and from reported values from water-supply 

managers. A potentiometric-surface map of the Springfield 

Plateau aquifer (fig. 31) was constructed using 15 water-level 

observations collected in 2006 as well as several spring orifice 

altitudes and streambed elevation values. A potentiometricsurface map of the Ozark aquifer (fig. 3) was constructed 

by Richards and Mugel (2008) from 119 water-level 

measurements collected from 115 wells. 

The model was calibrated to water-level observations 

compiled from multiple sources with differing levels of data 

quality (fig. 8). The steady-state stress period of the model 

was calibrated to 48 interpolated points from maps of the 

predevelopment surface of the Springfield Plateau and Ozark 

aquifers (Imes, 1990a and 1990b) and 34 measured values 

in the Ozark aquifer obtained from the Missouri Department 

of Natural Resources (2007) database of geologically 

logged wells. For the transient stress periods, the data came 

from measured water levels collected by the USGS during 

2006–07 and previously measured data contained in the 

USGS National Water Information System (http://water.

data.usgs.gov/nwis) database. Well construction data for 

these wells were evaluated, and 507 wells were selected for 

use as observation points in the model calibration. A second 

source of data was from the Missouri Department of Natural 

Resources (2007) database of geologically logged wells. 

Nine wells were found to be suitable for use as observation 

points in the model calibration based on construction data. 

The last source was from the Missouri Department of Natural 

Resources (2007) database of certified wells that were drilled 

in Missouri after 1987. These data are less reliable because 

the location information, date, construction information, and 

water level, were often not sufficiently documented. However, 

the value of having a large number of data points outweighed 

the suspected quality issues. To minimize the error associated 

with incorrectly located wells from the certified well database 

or well log database, wells with differences greater than 30 ft 

between the well land-surface altitude stated in the database 

and the altitude of the land surface at that point obtained from 

the USGS DEM were not included as observation points. 

Evaluation of construction data for these wells led to the 

selection of 1,569 wells suitable for use as an observation 

point in the model calibration. A total of 2,076 water-level 

measurements were used as observation points for the 

transient model calibration (fig. 8).

Although the difference between simulated head and 

observed water levels was tested at all of the 2,076 observation 

points, the primary focus of the transient calibration were 

water-level measurements completed within the model area 

during 1987, 1993, 1996, and 2006 in the Ozark aquifer 

and in 1989 and 2006 in the Springfield Plateau aquifer 

(table 9). The 2006 data set collected in the Ozark aquifer was 

the most geographically widespread and was considered the 

most important of the mass water-level measurement events. 

The primary focus of calibration was to match the simulated 
Model Calibration 63

head with the observed water levels in the Ozark aquifer 

through time; matching simulated head in the Springfield 

Plateau aquifer, streamflow and spring flow were secondary. 

Because of this, the relatively few (15) 2006 data points in the 

Springfield Plateau aquifer (most of layer 1), and the fact that 

the streamflow and spring flow values were estimated, made 

these observations less important during model calibration. 

Most adjustments to the model variables were made to 

improve the fit between the simulated head and observed 2006 

water levels in the Ozark aquifer (layer 3).

Model fit was evaluated by computing the root mean 

square error (RMSE), which is a measure of the variation 

between the simulated and observed values. Model fit is 

improved by minimizing the RMSE. The equation to calculate 

the RMSE is:

 

 

 (1)

where,

O is the observed water-level altitude in feet,

S is the simulated head in feet, and

n is the number of observations tested.

The accuracy of water-level measurements was the 

basis for choosing the RMSE used to determine if the model 

simulation was acceptable. Most water levels collected by 

USGS were measured with an electric tape, sonic meter, air 

line reading, or transducer. Practical experience indicates that 

air line readings are the least accurate and can typically be 

in error plus or minus (+/-) 20 to 25 ft of the true water-level 

altitude. Techniques used to measure or estimate historical 

water levels in wells, water levels collected from the certified 

well database, and water levels collected from the well log 

database were not documented. 

A second component of accuracy of the water-level 

measurements is the measuring-point altitude. For the 2006 

data, most of the measuring points were located with handheld global positioning system (GPS) devices; however, most 

of the measuring-point altitudes were interpolated from USGS 

1:24,000 scale topographic maps. Vertical accuracy of altitude 

data obtained from topographic maps is one-half of the 

contour interval on the map. Topographic maps of the model 

area have a contour interval of 10 or 20 ft, so the accuracy of 

the measuring point altitudes for these wells is +/- 5 or 10 ft. 

Water levels naturally fluctuate throughout the year 

in response to pumping stresses, flux to springs and rivers, 

and recharge from precipitation. Neither precipitation nor 

pumping is evenly distributed throughout the year, however, 

in the model, annual recharge and annual pumpage are applied 

uniformly throughout the year. The natural fluctuation in the 

monitoring well at Marshfield (fig. 2) completed in the Ozark 

aquifer for the period January 1, 2006, to December 31, 2009 

is shown in figure 32 (http://waterdata.usgs.gov/mo/nwis/

uv/?site_no=372022092542201&PARAmeter_cd=72019). 

Water-level measurements are an instantaneous measure 

of a dynamic system. Because of the way stresses are applied 

in the groundwater model, the natural fluctuation observed 

in the groundwater system was converted into a mean annual 

fluctuation. Precisely matching instantaneous water-level 

measurements with these mean simulated values is unlikely. 

The accuracy of the model fit thus depends on the timing of 

the water-level measurements and the relation of that timing to 

the groundwater natural fluctuation cycle. This is complicated 

by the fact that the magnitude of groundwater fluctuation is 

not uniform spatially in the aquifer, which in turn is related 

to the stresses and the hydraulic properties of the aquifer. A 

third component of accuracy of the water-level measurement 

relative to the model simulated head is the annual fluctuation 

of the potentiometric surface in the aquifer. For the Ozark 

aquifer at the Marshfield monitoring well (fig. 2), the mean 

daily water-level altitude for the period of record from 

January 1, 2006 to December 31, 2009 was 1,233 ft and the 

standard deviation was 12.6 ft (fig. 32). Ninety-five percent 

of the water levels measured in that well would be within 

+/- 24.7 ft of the mean. If it is assumed that this variability 

applies to all measurements in the Ozark aquifer, then for 

any given water-level measurement, there is a 95-percent 

confidence that the measurement is within +/- 24.7 ft of the 

mean value. 

The maximum assumed error for water-level 

measurements (+/- 35 ft) is the sum of the maximum errors 

caused by the water-level measurement errors and measuringpoint altitude errors. When combining this error with the 

assumed water-level fluctuation error (+/- 24.7 ft), the largest 

possible error in water-level altitude becomes approximately 

+/- 60 ft. The chance that the maximum error would occur is 

small; however, knowledge of the maximum error is necessary 

to assess the RMSE model fit to observed data.

Mean error is a measure of systematic error. It 

approaches zero when the sum of the measured differences 

between simulated head and observed water-level altitudes 

that are greater than zero equals the sum of the differences 

that are less than zero. A negative mean error indicates that 

the simulated head is on average greater than the observed 

water-level altitudes.

In both layers 1 and 3, fit between the simulated head 

and observed water-level altitudes was good in the steadystate and transient parts of the calibrated model. For the 

steady-state stress period that simulated the predevelopment 

conditions, the RMSE was 37.8 ft for layer 1 and 44.5 ft 
64 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 31. Potentiometric surface of the Springfield Plateau aquifer, 2006.

CHESAPEAKE 

FAULT

BATTLEFIELD-SAC RIVER FAULT

GRAYDON  SPRINGS  FAULT

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

900

1,200

900

1,400

1,200

1,200

1,500

1,400

1,200

09 0

1,100

1,000

1,400

1 3, 00

1,100

1 1, 00

1 3, 00

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

Western Interior Plains  confining systemSpringfield Plateau aquiferOzark confining unitOzark aquifer

Potentiometric contour

—

 Shows altitude at which water  would have stood in tightly cased well. Contour interval 100 feet.  Datum is National Geodetic Vertical Datum 1929.

900

Fault—bar and ball on down- thrown side
Model Calibration 65Figure 32. Daily water-level altitude of the Ozark aquifer at the Marshfield monitoring well from January 1, 2006, to December 31, 2009.

1,2501,2401,2301,2201,2101,2001,190

2006 / 1/ 1

2006 / 1/ 4

2006 / 1/ 7

2006 / 1/ 10

2007 / 1/ 1

2007 / 1/ 4

2007 / 1/ 7

2007 / 1/ 10

2008 / 1/ 1

2008 / 1/ 4

2008 / 1/ 7

2008 / 1/ 10

2009 / 1/ 1

2009 / 1/ 4

2009 / 1/ 7

2009 / 1/ 10

2010 / 1/ 1

THE NATIONAL GEODETIC VERTICAL DATUM OF 1929 T ABOVE EEF IN, EDUTI LT ALEVEL- RETA W

DATE

MEAN WATER LEVEL = 1,233 FEET

STANDARD DEVIATION 12.6 FEET

STANDARD DEVIATION 12.6 FEET
66 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

for layer 3 and the mean error was -0.93 ft for layer 1 and 

-0.63 ft for layer 3. The errors between the simulated head 

and observed water-level altitudes in layer 1 and layer 3 were 

evenly distributed with the majority of the difference values 

concentrated around zero. The calibration for the transient 

part of the simulation was focused on the period from 1987 to 

2006. Water-level measurements made by the USGS in 1987, 

1993, 1996, and 2006 in the Ozark aquifer and in 1989 and 

2006 in the Springfield Plateau aquifer are more numerous and 

are more reliable than other time periods (table 9). These data 

were useful for evaluating the model fit, and the following 

discussion is restricted to those time periods. Maps showing 

the difference between simulated head and observed waterlevel altitudes in layer 3 of the model for 1987, 1993, 1996, 

and 2006 time periods are shown in fig. 33, 34, 35, and 36. 

Blue symbol colors represent areas where the simulated 

surface is higher in altitude than the observed water levels, 

whereas the red symbol colors represent areas where the 

simulated surface is lower in altitude than the observed water 

levels. Simulated values within 25 ft of the observation 

value are shown by a triangle, between 25 ft and 50 ft are 

shown by a circle, and greater than 50 ft are shown by a 

square. Simulated values with differences greater than 50 ft 

from the observed values were labeled with the difference 

on the figures. The magnitude of the difference between the 

simulated head and observed water levels for the 2006 data 

generally was small (< 25 ft) and most of the differences near 

the largest pumping centers in Nixa, Ozark, and Republic were 

less than 50 ft (fig. 36). Only two wells east of Springfield had 

differences greater than 100 ft.

Model fit can also be examined graphically by plotting 

the simulated head with the observed water-level altitudes 

and determining the correlation coefficient (R2) of the linear 

regression line (Helsel and Hirsch, 1992). The correlation 

coefficient measures the fit between simulated and observed 

values; an R2 = 1 indicates a perfect fit. Plots of the relation 

between the simulated head and observed water-level altitudes 

in layer 3 for the 1987, 1993, 1996, and 2006 time periods are 

shown in figure 37. The correlation coefficient ranged from 

approximately 0.84 in 1996 to 0.94 in 2006 indicating a good 

correlation between the simulated head and observed waterlevel altitudes in layer 3. In layer 3, the RMSE was greatest for 

the 1996 data (65.7 ft), and smallest for the 2006 data (34.9 ft). 

In layer 3, the mean error for the 2006 data was -8.40 ft.

Histograms of the difference between the simulated head 

and observed water-level altitudes (observed minus simulated) 

can be used to graphically evaluate the distribution of the 

errors. Ideally, the histogram would be symmetric about the 

mean of the data with the largest number of errors near the 

mean value, and it would have a relatively narrow range with 

few extremely large or small values. Histogram plots of the 

difference between simulated head and observed water-level 

altitudes in layer 3 for the 1987, 1993, 1996, and 2006 time 

periods are shown in figure 38. The 1987, 1996, and 2006 data 

sets in layer 3 were evenly distributed with the majority of the 

difference values concentrated around zero. The 1993 data 

set in layer 3 had a good distribution but had a positive skew, 

indicating that the simulated head was lower than the observed 

water-level altitudes for many of the observations for that year. 

Maps showing the difference between simulated head and 

observed water-level altitudes in model layer 1 for the 1989 

and 2006 time periods are shown in figure 39 and 40. Plots of 

the relation between the simulated head and observed waterlevel altitudes in layer 1 for the 1989 and 2006 time periods 

are shown in figure 41. Histogram plots of the difference 

between simulated head and observed water-level altitudes 

in layer 1 for the 1989 and 2006 time periods are shown in 

figure 42. The majority of the water-level observations were in 

the northwestern quarter of the model area for the layer 1 data 

sets in 1989 and 2006. The majority of the difference values 

were within +/- 50 ft from the observed water-level altitudes 

for both data sets in layer 1. The RMSE in layer 1 was 47.4 ft 

with a mean error of 0.15 ft for the 1989 data, and the RMSE 

was 32.4 ft with a mean error of 7.60 ft for the 2006 data. 

Correlation of the simulated head and observed water levels 

in layer 1 was better in 2006 than in 1989. The center of the 

error distribution for both the 1989 and 2006 data in layer 1 

was near zero with the majority of values concentrated near 

the center.

All of the water-level observation data from 1987 

to 2006 (fig. 8) also can be used to evaluate model fit as 

shown in figure 43. These data are more extensive than the 

previously discussed observation data sets, which allows for 

an evaluation of the model fit over more of the model temporal 

and spatial domain. The following discussion is based on 

all of the observation data from 1987 to 2006. It should be 

noted that including water-level data from the Missouri DNR 

certified well database and the well log database, in addition to 

combining all years together, will cause the error to increase, 

primarily because of the inherent accuracy of the water-level 

measurements and well locations. However, the RMSE of the 

data by model layer is very close to the previously computed 

maximum data error of approximately 60 ft. It should also 

be noted that layer 1 observation data includes water levels 

measured in the Springfield Plateau aquifer and the Ozark 

aquifer. Layer 1 Ozark aquifer wells generally were shallow 

wells measured where the Ozark aquifer crops out. Plots of 

the relation between the simulated head and observed waterlevel altitudes in layer 1 and layer 3 are shown in figure 43. 

Histogram plots of the difference between simulated head and 

observed water-level altitudes (observed minus simulated) 

in layer 1 and layer 3 are shown in figure 44. Using all of the 

data in layer 1 from 1987 to 2006, the RMSE was 47.4 ft and 

the mean error was 7.12 ft. The simulated head compared to 

observed water-level altitudes for layer 1 had a correlation 

coefficient of approximately 0.81. The histogram plot of 

the error data for layer 1 was evenly distributed and had the 

majority of the errors near the center of the distribution. Using 

all of the data in layer 3 from 1987 to 2006, the RMSE was 

65.9 ft and the mean error was 26.0 ft. The simulated head 

compared to observed water-level altitudes for layer 3 had a 

correlation coefficient of approximately 0.81. The histogram 
Model Calibration 67Figure 33. Simulated head in layer 3 and the difference between simulated head and observed water-level altitudes at observation points, 1987.

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Springfield

Ozark

Nixa

Republic

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River Stockton Lake

Fellows

Lake McDaniel Lake

Lake

Springfield

-53

56

54

135

-53

-70

62

-134

-152

54 62

-65

800

1,000

1 2, 00

1,150

1,450

850

900

900

900

1,250

950

950

1 2, 00

950

1,400

1 1, 50

1 0, 00

1 3, 50

1,100

1 3, 00

1,050

1,250

1 0, 00

1,050

1 2, 00

1,150

1,100

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

Line of equal simulated head,  in feet. Contour interval 50 feet.  Datum is National Geodetic Vertical Datum 1929.

900

< -50> -50 to -25> -25 to 0> 0 to 25> 25 to 50> 50

Difference between simulated head and observed water-level altitudes (observed minus simulated), in feet (values indicate difference if less than (<) -50 or greater than (>)  50 feet)

Simulated greater

than observed

Simulated less

than observed

-58

67

Incorporated area

1,600

800600400200

Simulated head, in feet

1,4001,2001,000
68 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 34. Simulated head in layer 3 and the difference between simulated head and observed water-level altitudes at observation points, 1993.

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Springfield

Ozark

Nixa

Republic

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River

Finley Creek

Stockton

Lake

Fellows

Lake

McDaniel

Lake

Lake

Springfield

59

54

50

145

81

800

1,000

1,150

1 2, 00

1,450

850

900

900

900

1,250

950

950

950

1,400

1 2, 00

1 1, 50

1 0, 00

1 3, 50

1,100

1 3, 00

1,050

1,250

1,000

0, 1 05

1 2, 00

1,150

1,100

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

Line of equal simulated head,  in feet. Contour interval 50 feet.  Datum is National Geodetic Vertical Datum 1929.

900

< -50> -50 to -25> -25 to 0> 0 to 25> 25 to 50> 50

Difference between simulated head and observed water-level altitudes (observed minus simulated), in feet (values indicate difference if less than (<) -50 or greater than (>)  50 feet)

Simulated greater

than observed

Simulated less

than observed

-58

67

Incorporated area

1,600

800600400200

Simulated head, in feet

1,4001,2001,000
Model Calibration 69Figure 35. Simulated head in layer 3 and the difference between simulated head and observed water-level altitudes at observation points, 1996.

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Springfield

Ozark

Nixa

Republic

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River Stockton Lake

Fellows

Lake McDaniel Lake

Lake

Springfield

71

87

76

-111

112

52

-186

72

-53

-72

119

-145

65

57

62

800

1,000

1 2, 00

1,150

1 4, 50

850

900

900

900

1,250

950

950

1,400

1 2, 00

950

1 1, 50

1 0, 00

1,350

1,100

1 3, 00

1,050

1,250

1,000

1,050

1 2, 00

1,150

1,100

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

Line of equal simulated head,  in feet. Contour interval 50 feet.  Datum is National Geodetic Vertical Datum 1929.

900

< -50> -50 to -25> -25 to 0> 0 to 25> 25 to 50> 50

Difference between simulated head and observed water-level altitudes (observed minus simulated), in feet (values indicate difference if less than (<) -50 or greater than (>)  50 feet)

Simulated greater

than observed

Simulated less

than observed

-58

67

Incorporated area

1,600

800600400200

Simulated head, in feet

1,4001,2001,000
70 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 36. Simulated head in layer 3 and the difference between simulated head and observed water-level altitudes at observation points, 2006.

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Springfield

Ozark

Nixa

Republic

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River Stockton Lake

Fellows

Lake McDaniel Lake

Lake

Springfield

-53

-62

-112

-62

63

-56

50

66

-69

-74

77

-61

-91 -77

-117

-94

-82 -59

800

850

1,000

850

1 2, 00

1,450

850

1,150

900

900

1,250

950

900

1 4, 00

950

1 2, 00

1,150 1 0, 00

1,350

1,100

1,050

950

1 3, 00

1 2, 50

2, 1 00

1,100

1,000

0, 1 05

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

Line of equal simulated head,  in feet. Contour interval 50 feet.  Datum is National Geodetic Vertical Datum 1929.

900

< -50> -50 to -25> -25 to 0> 0 to 25> 25 to 50> 50

Difference between simulated head and observed water-level altitudes (observed minus simulated), in feet (values indicate difference if less than (<) -50 or greater than (>)  50 feet)

Simulated greater

than observed

Simulated less

than observed

-58

67

Incorporated area

1,600

800600400200

Simulated head, in feet

1,4001,2001,000
Model Calibration 71

900800700

1,6001,5001,4001,3001,2001,1001,000

700 800 900 1,000 1,100 1,200 1,300 1,400 1,500 1,600

OBSERVED WATER-LEVEL ALTITUDE, IN FEET ABOVE NGVD 29

Ozark aquifer water-level observations for 2006Correlation coefficient (R2) = 0.9420Range in observed values = 704.1 feet Mean error = -8.40 feetRoot Mean Square Error = 34.9 feet

900800700

1,6001,5001,4001,3001,2001,1001,000

700 800 900 1,000 1,100 1,200 1,300 1,400 1,500 1,600

SIMULATED HEAD, IN FEET SIMULATED HEAD, IN FEET

OBSERVED WATER-LEVEL ALTITUDE, IN FEET ABOVE NGVD 29

Ozark aquifer water-level observations for 1996

Correlation coefficient (R2) = 0.8382Range in observed values = 723 feetMean error = -8.40Root Mean Square Error = 65.7 feet

900800700

1,6001,5001,4001,3001,2001,1001,000

700 800 900 1,000 1,100 1,200 1,300 1,400 1,500 1,600

Ozark aquifer water-level observations for 1993Correlation coefficient (R2) = 0.9147Range in observed values = 509 feetMean error = 33.3 feetRoot Mean Square Error = 48.1 feet

900800700

1,6001,5001,4001,3001,2001,1001,000

700 800 900 1,000 1,100 1,200 1,300 1,400 1,500 1,600

Ozark aquifer water-level observations for 1987

Correlation coefficient (R2) = 0.8515Range in observed values = 508 feet Mean error = 0.90 feetRoot Mean Square Error = 48.1 feet

Figure 37. Relation between simulated head and observed water-level altitudes for selected measurements for layer 3 in the model.
72 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

50

3025201510

2006

0

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

DIFFERENCE BETWEEN SIMULATED HEAD AND OBSERVED WATER-LEVEL ALTITUDES, IN FEET

6543210

1996

0

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

SECNER OCCUR OF REB MUN SECNER OCCUR OF REB MUN

DIFFERENCE BETWEEN SIMULATED HEAD AND OBSERVED WATER-LEVEL ALTITUDES, IN FEET

76543210

1993

0

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

1987

87654320 0

-150

-140

-130

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

1

Figure 38. Difference between simulated head and observed water-level altitudes (observed minus simulated) for selected measurements for layer 3 in the model.
Model Calibration 73Figure 39. Simulated head in layer 1 and the difference between simulated head and observed water-level altitudes at observation points, 1989.

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Springfield

Ozark

Nixa

Republic

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River Stockton Lake

Fellows

Lake McDaniel Lake

Lake

Springfield

-108

106

-62

-63

-75

62

117

97

-64

106

59

60

114

-68 -65

97

-115

900

900

950

1,000

1,100

1,350

900

900

1,150

1,100

1,050

1 5, 50

3, 1 05

1,300

0, 1 05

950

1 5, 00

1,300

1 0, 00

1,050 1 1, 00

1,200

1 4, 50

1,100

1 2, 50

1,400

1,350

1,300

950

1,100

1,050

1 1, 50

1,000

1,150

1 2, 50

1 2, 00

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

Line of equal simulated head,  in feet. Contour interval 50 feet.  Datum is National Geodetic Vertical Datum 1929.

900

< -50> -50 to -25> -25 to 0> 0 to 25> 25 to 50> 50

Difference between simulated head and observed water-level altitudes (observed minus simulated), in feet (values indicate difference if less than (<) -50 or greater than (>)  50 feet)

Simulated greater

than observed

Simulated less

than observed

-58

67

Incorporated area

1,600

800600400200

Simulated head, in feet

1,4001,2001,000
74 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 40. Simulated head in layer 1 and the difference between simulated head and observed water-level altitudes at observation points, 2006.

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

Springfield

Ozark

Nixa

Republic

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River Stockton Lake

Fellows

Lake McDaniel Lake

Lake

64

Springfield

50

900

900

950

1,000

1,100

1,350

900

900

1,150

1,100

1,050

1 3, 50

1 5, 50

1,300

950

, 1 0 05

1 5, 00

1,300

1 0, 00

1,050

1,200

1 1, 00

1,450

1,100

1 2, 50

1,400

1,350

1,300

950

1,100

1 1, 50

1,050

1,000

1,150

1 2, 50

, 1 02 0

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

Line of equal simulated head,  in feet. Contour interval 50 feet.  Datum is National Geodetic Vertical Datum 1929.

900

< -50> -50 to -25> -25 to 0> 0 to 25> 25 to 50> 50

Difference between simulated head and observed water-level altitudes (observed minus simulated), in feet (values indicate difference if less than (<) -50 or greater than (>)  50 feet)

Simulated greater

than observed

Simulated less

than observed

-58

67

Incorporated area

1,600

800600400200

Simulated head, in feet

1,4001,2001,000
Model Calibration 75

Figure 41. Relation between simulated head and observed water-level altitudes for selected measurements for layer 1 in the model.

700

800

900

1,000

1,100

1,200

1,300

1,400

1,500

1,600

700 800 900 1,000 1,100 1,200 1,300 1,400 1,500 1,600

SIMULATED HEAD, IN FEET SIMULATED HEAD, IN FEET

OBSERVED WATER-LEVEL ALTITUDE, IN FEET ABOVE NGVD 29

Layer 1 water-level observations for 2006

Correlation coefficient (R2) = 0.9198

Range in observed values = 372.5 feet 

Mean error = 7.60 feet

Root Mean Square Error = 32.4 feet

700

800

900

1,000

1,100

1,200

1,300

1,400

1,500

1,600

700 800 900 1,000 1,100 1,200 1,300 1,400 1,500 1,600

Layer 1 water-level observations for 1989

Correlation coefficient (R2) = 0.6368

Range in observed values = 427 feet 

Mean error = 0.15 feet

Root Mean Square Error = 47.4 feet
76 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 42. Difference between simulated head and observed water-level altitudes (observed minus simulated) for selected 

measurements for layer 1 in the model.

0

1

2

3

4

5

2006

0

-150-140-130-120-110-100

-90-80-70-60-50-40-30-20-10

102030405060708090

100110120130140150

NUMBER OF OCCURRENCES NUMBER OF OCCURRENCES

DIFFERENCE BETWEEN SIMULATED HEAD AND OBSERVED WATER-LEVEL ALTITUDES, IN FEET

0

1

2

3

4

5

6

7

8

9

10

11

1989

0

-150-140-130-120-110-100

-90-80-70-60-50-40-30-20-10

102030405060708090

100110120130140150
Model Calibration 77

Figure 43. Relation between simulated head and observed water-level altitudes for all measurements made from 1987 to 2006 for 

layer 1 and layer 3 in the model.

700

800

900

1,000

1,100

1,200

1,300

1,400

1,500

1,600

700 800 900 1,000 1,100 1,200 1,300 1,400 1,500 1,600

SIMULATED HEAD, IN FEET SIMULATED HEAD, IN FEET

OBSERVED WATER-LEVEL ALTITUDE, IN FEET ABOVE NGVD 29

Layer 3 water-level observations for 1987-2006

Correlation coefficient (R2) = 0.8068

Range in observed values = 851.5 feet 

Mean error = 26.0 feet

Root Mean Square Error = 65.9 feet

700

800

900

1,000

1,100

1,200

1,300

1,400

1,500

1,600

700 800 900 1,000 1,100 1,200 1,300 1,400 1,500 1,600

Layer 1 water-level observations for 1987-2006

Correlation coefficient (R2) = 0.8134

Range in observed values = 541 feet 

Mean error = 7.12 feet

Root Mean Square Error = 47.4 feet
78 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 44. Difference between simulated head and observed water-level altitudes (observed minus simulated) for all measurements 

made from 1987 to 2006 for layer 1 and layer 3 in the model.

0

20

40

60

80

100

120

140

Layer 1

-250-225-200-175-150-125-100

-75-50-25

0

255075

100125150175200225250

0

50

100

150

200

250

300

Layer 3

-250-225-200-175-150-125-100

-75-50-25

0

255075

100125150175200225250

NUMBER OF OCCURRENCES NUMBER OF OCCURRENCES

DIFFERENCE BETWEEN SIMULATED HEAD AND OBSERVED WATER-LEVEL ALTITUDES, IN FEET
Model Calibration 79

plot of the error data for layer 3 was evenly distributed and 

had the largest concentration of errors near the center of the 

distribution. 

Streamflow Observations

Low-flow seepage-run data collected by Emmett and 

others (1978) and USGS in 2006 (fig. 23) were used to help 

estimate base-flow rates for selected sites. Base-flow rates 

for selected sites were also estimated from computed USGS 

7Q2 low-flow frequency data at gaged sites and estimated 

at ungaged sites (table 6). Streamflow in the area is largely 

influenced by the karst groundwater system with discrete 

discharge in the river channel and long losing stream reaches. 

The model simulates diffuse discharge to, or recharge from 

the groundwater to the streams. Matching flows to streams 

and springs in this hydrogeologic setting with a groundwater 

model is challenging. In addition to the karst system, several 

lakes that provide drinking water or cooling water are located 

on the rivers. The process of removing drinking water from 

a lake in one basin (McDaniel Lake and Fellows Lake in 

the Little Sac River Basin) and discharging the water as 

wastewater effluent into another basin (Wilsons Creek in the 

James River Basin) complicates the base-flow estimates to the 

rivers. Base-flow estimates had to be corrected using discharge 

estimates from the wastewater-treatment facilities in the basin. 

To help reduce the effects of karst flow and other complicating 

factors at individual stream reaches, river basins at selected 

gaged sites and some ungaged sites were used to evaluate the 

groundwater flow to the rivers in the model (table 6).

Because the mean rainfall for the period 1987 to 2006 

was 44.16 inches and was close to the 44.97 in/yr mean 

annual rainfall for the period 1971–2000 (National Climatic 

Data Center, 2008), the 7Q2 values were compared to the 

simulated discharge at the observation points near the end 

of the simulation in 2006. The relative percent difference 

between simulated and observed streamflow ranged from 6 to 

141 percent (table 6) with a median relative percent difference 

of 40 percent. Taken as a whole, total observed 7Q2 discharge 

in rivers was 11,998,548 ft3/d, compared to total simulated 

discharge from the model to rivers of 11,155,870 ft3/d, or a 

relative percent difference of 7 percent. 

Spring-Flow Observations

Spring-flow observation data were obtained or inferred 

from data available in Missouri Department of Natural 

Resources (2007), Vineyard and Feder, (1982), and Bullard 

and others (2001) for springs with a mean discharge of 

86,400 ft3/d (1 ft3/s) or greater. Not all springs occurring in 

the model area were included in the model. The difference 

between simulated and observed spring discharge is listed 

in table 7. The relative percent error between simulated and 

observed spring discharge ranged from 65 to 200 percent. 

Taken as a whole, total observed discharge from springs in the 

model was 9,792,645 ft3/d, compared to the total simulated 

discharge of 666,976 ft3/d, or a relative percent difference of 

174 percent (table 7). Error between simulated and observed 

spring discharge may be caused by uncertainty in the observed 

spring discharge and uncertainty in the simulated spring 

discharge related to the model grid spacing, horizontal and 

vertical hydraulic conductivity errors, proximity to other 

boundary conditions, and karst conduit flow. The grid spacing 

might affect the simulated discharge because the land-surface 

altitude of the cells was averaged over a 1,000-ft by 1,000-ft 

area. This has the effect of lowering the overall land-surface 

altitude in steep terrain where many springs discharge from 

hillsides adjacent to rivers. As a result, the spring altitude may 

be too high relative to the land-surface altitude. Hydraulic 

conductivity errors can cause flow to be restricted at the 

spring. Springs in close proximity to another model boundary, 

such as a river cell, may receive less flow when water that 

would have discharged to the spring is redirected toward the 

river. Because the model is simulating groundwater flow as 

porous-media flow, the karst flow to springs by conduit flow is 

not adequately represented. 

The majority of spring flow in the model area ultimately 

flows to a river by overland flow and is removed from the 

model area as streamflow. Even though spring flow is under 

simulated in the model, the total volume of water leaving 

the model area, estimated by 7Q2 low-flow discharge, 

includes spring flow. When water discharges to a spring, the 

groundwater model removes that discharge and it cannot 

reenter the system. If the simulated stream discharge matched 

the estimated stream discharge and the simulated spring 

discharge matched the estimated spring discharge, then, in 

effect, spring flow would be counted twice. The springs in the 

model represent maximum water-level altitudes in those cells 

and help locally constrain the head distribution in layer 1 of 

the model.

Water Budget

The water budget was computed using ZONEBUDGET 

(Harbaugh, 1990) to determine the volumetric flow rate of 

water through the model. The flow budget is identical from 

stress period 1 (initial steady-state stress period) through stress 

period 101 (year 2006) and is similar for stress periods 102 

(year 2007) through 125 (year 2030) in all model scenarios. 

The computed flow budget for the three layers in the model at 

the end of the initial steady-state stress period, the 101st stress 

period (year 2006), and the 125th stress period (year 2030) for 

hypothetical scenario 7 is shown in table 12. Total input into 

the model for hypothetical scenario 7 computed as the sum of 

the storage, rivers, general heads, and recharge inputs for the 

three layers of the model (table 12) was 23,660,140 ft3/d for 

the initial steady-state stress period, 24,354,810 ft3/d for 2006, 
80 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030 Table 12. Flow budget for the three layers of the model at the end of the initial steady-state stress period, the 101st stress period (2006), and the 125th stress period (2030) for hypothetical scenario 7. [ft3/d, cubic foot per day; LAYER 1, model layer 1; LAYER 2, model layer 2; LAYER 3, model layer 3; —, no data; <, less than; zero flow-budget terms not included in table; values have been rounded] Flow compo- nent Initial steady-state stress period 2006 2030 scenario 7 LAYER 1 LAYER 2 LAYER 3 LAYER 1 LAYER 2 LAYER 3 LAYER 1 LAYER 2 LAYER 3 ft3/d per- cent ft3/d per- cent ft3/d per- cent ft3/d per- cent ft3/d per- cent ft3/d per- cent ft3/d per- cent ft3/d per- cent ft3/d per- cent In Storage 

—

—

—

—

—

— 941,920 4 150,150 1 1,987,300 16 314,860 1 176,470 1 2,806,300 18

Rivers 1,173,100 4 0 0 0 0 1,496,100 6 0 0 0 0 1,672,200 6 0 0 0 0General 

Heads 775,990 3 868,550 6 112,500 1 813,170 3 887,640 6 160,530 1 783,450 3 890,250 5 175,380 1

Recharge 20,730,000 74 0 0 0 0 17,918,000 70 0 0 0 0 20,713,000 75 17,088 < 1 0 0From 

Layer 1

—

— 9,699,600 65

—

—

—

— 10,492,000 70

—

—

—

— 12,643,000 74

—

—

From 

Layer 2 5,226,200 19

—

— 9,513,300 99 4,260,300 17

—

— 10,632,000 83 4,121,300 15

—

— 12,828,000 81

From 

Layer 3

—

— 4,304,000 29

—

—

—

— 3,483,500 23

—

—

—

— 3,350,700 20

—

—

Total In 27,905,000 14,872,000 9,625,800 25,429,000 15,013,000 12,780,000 27,605,000 17,078,000 15,810,000

 Out

Storage 

—

—

—

—

—

— 6,175 < 1 320 < 1 19,586 < 1 5,762 < 1 436 < 1 2,702 < 1

Wells 0 0 0 0 0 0 0 0 0 0 4,330,200 34 0 0 0 0 7,582,600 48Springs 785,240 3 0 0 0 0 666,260 3 0 0 0 0 663,360 2 0 0 0 0Rivers 16,260,000 58 0 0 0 0 13,217,000 52 0 0 0 0 13,167,000 48 0 0 0 0General 

Heads 1,160,700 4 132,330 1 5,319,000 55 1,047,300 4 121,070 1 4,944,800 39 1,124,900 4 127,760 1 4,872,700 31

To 

Layer 1

—

— 5,226,200 35

—

—

—

— 4,260,300 28

—

—

—

— 4,121,300 24

—

—

To 

Layer 2 9,699,600 35

—

— 4,304,000 45 10,492,000 41

—

— 3,483,500 27 12,643,000 46

—

— 3,350,700 21

To 

Layer 3

—

— 9,513,300 64

—

—

—

— 10,632,000 71

—

—

—

— 12,828,000 75

—

—

Total Out 27,905,000 14,872,000 9,623,000 25,429,000 15,013,000 12,778,000 27,605,000 17,078,000 15,809,000
Model Calibration 81

and 27,548,998 ft3/d for 2030. Additional ZONEBUDGET 

analyses were performed to determine only the flow 

component through the lateral model boundary from each 

model layer and flow through the bottom of layer 3 in the 

model, which are included in general heads in table 12. Flow 

through general-head boundaries representing lakes in layer 1 

are not included in the ZONEBUDGET following analysis. At 

the end of the initial steady-state stress period in scenario 7, 

there was a net flow of 2,240 ft3/d into layer 1, a net flow of 

736,220 ft3/d into layer 2, and a net flow of 3,305,900 ft3/d 

out of layer 3 through the lateral model boundary. Net flow 

through the bottom of layer 3 was 1,900,700 ft3/d out of the 

model, which represents about 8.0 percent of the total input to 

the model in the initial steady-state stress period. At the end 

of stress period 101 (year 2006) in scenario 7, there was a net 

flow of 114,010 ft3/d into layer 1, a net flow of 766,570 ft3/d 

into layer 2, and a net flow of 3,001,670 ft3/d out of layer 3 

through the lateral model boundary. Net flow through the 

bottom of layer 3 was 1,782,500 ft3/d out of the model, which 

represents about 7.3 percent of the total input to the model in 

2006. At the end of stress period 125 (year 2030) in scenario 7, 

there was a net flow of 28,570 ft3/d into layer 1, a net flow of 

762,490 ft3/d into layer 2, and a net flow of 3,004,850 ft3/d 

out of layer 3 through the lateral model boundary. Net flow 

through the bottom of layer 3 was 1,692,800 ft3/d out of the 

model, which represents about 6.1 percent of the total input to 

the model in 2030 for hypothetical scenario 7. 

Sensitivity Analysis

Sensitivity analysis of the model was performed to 

assess the response of the model to changes in the various 

input parameters used in the model. Every change to a model 

parameter in this model will cause changes to the distribution 

of head in the aquifers and subsequently, discharge to 

rivers and springs. The model is considered sensitive to the 

parameter when a small change in the parameter causes a large 

change in the distribution of simulated head. When the model 

is sensitive to a parameter, the parameter is more accurately 

determined during model calibration. When a model is 

insensitive to a parameter, the parameter is less accurately 

determined during model calibration.

Horizontal hydraulic conductivity, vertical hydraulic 

conductivity, specific storage, and specific yield were tested 

for all zones in the Springfield Plateau aquifer, the Ozark 

confining unit, and the Ozark aquifer. In addition, spring drain 

conductance, lake general-head boundary conductance, river 

conductance, perimeter general-head boundary conductance in 

all layers, and recharge zone boundary conditions were tested. 

The calibration-period sensitivity test consisted of 

increasing each model parameter by 10 percent while 

holding the other parameters constant and running the 

model. Simulated head was compared between the calibrated 

model and the model results with the 10-percent parameter 

adjustments. The differences were computed by subtracting 

the head of the adjusted parameter model results from 

the head of the calibrated model at the 2,076 water-level 

observation points. The RMSE of these differences was 

computed and tabled by rank (table 13). The 10 most 

sensitive model parameters included the horizontal hydraulic 

conductivity in the Ozark aquifer in zones 1, 3, and 6 (fig. 30); 

recharge in zones 1 and 2 (fig. 19); the specific storage of 

the Ozark aquifer in zone 4 (fig. 30); and the vertical and 

horizontal hydraulic conductivity of the Ozark confining 

unit in zones 2 and 3 (fig. 29). The 10 least sensitive 

parameters were the specific yield in the Ozark aquifer in 

zones 8, 5, 6, 7, 2, and 4 (fig. 30); the specific storage in the 

Ozark aquifer in zone 7 (fig. 30); and the specific storage in 

the Springfield Plateau aquifer in zones 1, 2, and 3 (fig. 28). 

Sensitivity analysis was not performed on values of 

groundwater use because it was assumed that these values 

were better known than the parameters specified in the 

sensitivity analysis. 

Maps of the simulated head change between the 

calibrated model and the model with an adjusted hydraulic 

parameter can be examined to help understand how changes 

in hydraulic properties affect the simulated head distribution. 

Of the top five most sensitive parameters in the model, two 

were for horizontal hydraulic conductivity in the Ozark 

aquifer and two were for recharge. Maps of the simulated head 

change in layer 1 and layer 3 for the sensitivity parameters 

horizontal hydraulic conductivity in zone 1 of the Ozark 

aquifer (OZHK1, table 13; OZA1, fig. 30) and the recharge 

in zone 1 (RCHZ1, table 13; RCH1, fig. 19) are shown in 

figure 45 and 46. When the horizontal hydraulic conductivity 

of a particular zone is increased, the head gradient will 

decrease and the potentiometric surface will become flatter. 

The greatest changes will occur in the zone where the 

parameter was adjusted, however, some change will occur 

outside the zone. After the adjustment of the horizontal 

hydraulic conductivity in the Ozark aquifer zone 1, the 

simulated head in layer 3 (fig. 45; LAYER 3) increased in 

the vicinity of pumping wells in zone 1 of the Ozark aquifer 

in central Greene County and decreased in the northeastern, 

southwestern, and south-central part of the model area. 

Simulated head in layer 1 also decreased in approximately 

the same area as in layer 3 because the lower potentiometric 

surface in layer 3 allowed more water to pass through layer 2, 

which resulted in lower head in layer 1 (fig. 45; LAYER 1). 

When recharge is increased in a particular zone, the head 

tends to increase in all layers throughout the model. The 

magnitude of the simulated head increase in layer 1, the layer 

where recharge is applied, is greater than the magnitude in 

layer 3 (fig. 46). 
82 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030 Table 13. Sensitivity of model to changes in parameter values. [SPA, Springfield Plateau aquifer; OZCU, Ozark confining unit; OZA, Ozark aquifer; SFCU1, general-head boundary conductance simulating flow through the bottom of the Ozark aquifer in zone 1; SFCU2, general-head boundary conductance simulating flow through the bottom of the Ozark aquifer in zone 2; HK, horizontal hydraulic conductivity; KZ, vertical hydraulic conductivity; SS, specific storage; SY, specific yield; RCH, recharge; RIV, river conductance; SPRG, drain conductance; GHB, general-head boundary conductance; RBSP, river conductance for rivers flowing on the Springfield Plateau aquifer; RBCU, river conductance for rivers flowing on the Ozark confining unit; RBOZ, river conductance for rivers flowing on the Ozark aquifer; LAKE, general-head boundary conductance simulating lakes; GHB1, general-head boundary conductance simulating flow through model boundary in layer 1; GHB2, general-head boundary conductance simulating flow through model boundary in layer 2; GHB3, general-head boundary conductance simulating flow through model boundary in layer 3; RMSE, root mean square error; —, no data] Parameter name Calibration period Prediction period Hydrogeologic unit Parameter type Zone name Calibrated parameter value (variable units) RMSE Rank RMSE RMSE Rank RMSE OZHK1 2.048 1 3.850 1 OZA HK OZA1 1.30 RCHZ1 1.684 2 1.781 4 — RCH RCH1 Precipitation*3.0 percent OZSS4 1.425 3 2.983 2 OZA SS OZA4 1.00x10-4 OZHK3 1.373 4 1.352 10 OZA HK OZA3 .35 RCHZ2 1.354 5 1.410 9 — RCH RCH2 Precipitation*2.7 percent OZHK6 1.222 6 2.449 3 OZA HK OZA6 .30 CUKZ3 1.167 7 1.652 5 OZCU KZ OZCU3 1.50x10-5 CUHK3 1.157 8 1.616 6 OZCU HK OZCU3 7.50x10-5 CUHK2 .995 9 1.535 7 OZCU HK OZCU2 2.80x10-5 CUKZ2 .944 10 1.451 8 OZCU KZ OZCU2 5.60x10-6 SFCU1 .898 11 .816 13 SFCU GHB SFCU1 .035 SPHK2 .882 12 .880 12 SPA HK SPA2 2.20 RCHZ3 .707 13 .718 14

— RCH RCH3 Precipitation*2.1 percent

SFCU2 .656 14 .579 16 SFCU GHB SFCU2 .200SPHK3 .638 15 .579 15 SPA HK SPA3 5.00OZHK2 .384 16 .409 18 OZA HK OZA2 .35OZHK7 .360 17 .902 11 OZA HK OZA7 .80OZHK4 .352 18 .548 17 OZA HK OZA4 1.50SPHK1 .311 19 .313 23 SPA HK SPA1 2.50OZKZ3 .307 20 .321 22 OZA KZ OZA3 .035OZKZ1 .234 21 .342 20 OZA KZ OZA1 .130OZHK8 .234 22 .257 26 OZA HK OZA8 3.00RBOZ .230 23 .334 21 OZA RIV

— 975 to 9,750

OZHK5 .208 24 .301 24 OZA HK OZA5 .25GHB3 .200 25 .200 28

— GHB

— 59.9 to 1,288

OZSS1 .168 26 .237 27 OZA SS OZA1 1.00x10-6
Model Calibration 83

Parameter

name Calibration period Prediction period

Hydrogeologic

unit Parameter type Zone name

Calibrated

parameter value

(variable units)

RMSE Rank RMSE RMSE Rank RMSE

OZSS3 .103 27 .352 19 OZA SS OZA3 5.00x10-6OZSS5 .083 28 .261 25 OZA SS OZA5 5.00x10-5RBSP .075 29 .084 31 SPA RIV — 1,000 to 3,333OZSS2 .073 30 .181 30 OZA SS OZA2 5.00x10-4SPKZ2 .067 31 .066 34 SPA KZ SPA2 .073GHB1 .064 32 .064 35 — GHB — 11.5 to 530.6OZKZ6 .063 33 .182 29 OZA KZ OZA6 .030GHB2 .059 34 .060 38 — GHB — 4.56 to 105.0LAKE .039 35 .067 33 — GHB — 100SPKZ3 .032 36 .048 44 SPA KZ SPA3 .167OZSY1 .031 37 .046 46 OZA SY OZA1 .003CUHK1 .031 38 .042 47 OZCU HK OZCU1 1.00x10-6CUKZ1 .029 39 .061 36 OZCU KZ OZCU1 2.00x10-7SPSY2 .028 40 .004 62 SPA SY SPA2 .003OZKZ5 .027 41 .056 40 OZA KZ OZA5 .050CUSY1 .027 42 .035 48 OZCU SY OZCU1 .100OZKZ8 .026 43 .075 32 OZA KZ OZA8 .300RBCU .026 44 .055 41 OZCU RIV — 50 to 3,750SPKZ1 .025 45 .026 50 SPA KZ SPA1 .050SPSY3 .021 46 .008 57 SPA SY SPA3 .003CUSY2 .019 47 .047 45 OZCU SY OZCU2 .100OZSS8 .018 48 .030 49 OZA SS OZA8 1.00x10-5SPRG .018 49 .055 42 — SPRG — 10,000OZKZ7 .014 50 .058 39 OZA KZ OZA7 .080OZSS6 .012 51 .013 53 OZA SS OZA6 1.00x10-7OZKZ2 .012 52 .012 54 OZA KZ OZA2 .070OZSY3 .012 53 .010 56 OZA SY OZA3 .003
84 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030 Parameter name Calibration period Prediction period Hydrogeologic unit Parameter type Zone name Calibrated parameter value (variable units) RMSE Rank RMSE RMSE Rank RMSE CUSY3 .011 54 .060 37 OZCU SY OZCU3 .100 CUSS2 .006 55 .019 51 OZCU SS OZCU2 5.00x10-6 OZKZ4 .004 56 .006 58 OZA KZ OZA4 .150 CUSS1 .004 57 .011 55 OZCU SS OZCU1 5.00x10-6 SPSY1 .002 58 .001 66 SPA SY SPA1 .003 CUSS3 .002 59 .006 59 OZCU SS OZCU3 5.00x10-6 SPSS2 .002 60 .002 63 SPA SS SPA2 1.00x10-5 OZSS7 .002 61 .001 67 OZA SS OZA7 1.00x10-8 OZSY8 .001 62 .049 43 OZA SY OZA8 .003 OZSY5 .001 63 .002 65 OZA SY OZA5 .003 SPSS3 .001 64 .005 61 SPA SS SPA3 1.00x10-5 OZSY6 .001 65 .000 69 OZA SY OZA6 .003 OZSY7 .001 66 .019 52 OZA SY OZA7 .003 OZSY2 .001 67 .002 64 OZA SY OZA2 .003 SPSS1 .001 68 .000 68 SPA SS SPA1 1.00x10-5 OZSY4 .001 69 .005 60 OZA SY OZA4 .003 Table 13. Sensitivity of model to changes in parameter values.—Continued [SPA, Springfield Plateau aquifer; OZCU, Ozark confining unit; OZA, Ozark aquifer; SFCU1, general-head boundary conductance simulating flow through the bottom of the Ozark aquifer in zone 1; SFCU2, general-head boundary conductance simulating flow through the bottom of the Ozark aquifer in zone 2; HK, horizontal hydraulic conductivity; KZ, vertical hydraulic conductivity; SS, specific storage; SY, specific yield; RCH, recharge; RIV, river conductance; SPRG, drain conductance; GHB, general-head boundary conductance; RBSP, river conductance for rivers flowing on the Springfield Plateau aquifer; RBCU, river conductance for rivers flowing on the Ozark confining unit; RBOZ, river conductance for rivers flowing on the Ozark aquifer; LAKE, general-head boundary conductance simulating lakes; GHB1, general-head boundary conductance simulating flow through model boundary in layer 1; GHB2, general-head boundary conductance simulating flow through model boundary in layer 2; GHB3, general-head boundary conductance simulating flow through model boundary in layer 3; RMSE, root mean square error; —, no data]
Model Calibration 85

Figure 45. Simulated head change in layer 1 and layer 3 following a 10-percent increase in horizontal hydraulic conductivity in zone 1 

of the Ozark aquifer (OZHK1, table 13; OZA1, fig. 30) computed at the end of the calibration period in 2006.

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

93°30' 93°00'

37°30'

37°00'

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

93°30' 93°00'

37°30'

37°00'

0 10 20 MILES

0 10 20 KILOMETERS

LAYER 1

LAYER 3

EXPLANATION

River

Simulated head change in layer 1

 and layer 3 following a 10-

 percent increase in horizontal

 hydraulic conductivity in zone 1

 of the Ozark aquifer, in feet.

 Head change computed by 

 subtracting the 2006 simulated 

 head in the calibrated model

 from the 2006 simulated head in the 

 model with a 10-percent increase

 in horizontal hydraulic conductivity

 in zone 1 of the Ozark aquifer.

greater than 8

greater than 6 to 8

greater than 4 to 6

greater than 2 to 4

 0 to 2

greater than 0 to 2

greater than 2 to 4

greater than 4 to 6

greater than 6 to 8

INCREASE DECREASE

Observation point
86 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 46. Simulated head change in layer 1 and layer 3 following a 10-percent increase in recharge in areal recharge zone 1 

(RCHZ1, table 13; RCH1, fig. 19) computed at the end of the calibration period in 2006.

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

93°30' 93°00'

37°30'

37°00'

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

93°30' 93°00'

37°30'

37°00'

0 10 20 MILES

0 10 20 KILOMETERS

LAYER 1

LAYER 3

EXPLANATION

River

Simulated head change in layer 1

 and layer 3 following a 10-

 percent increase in recharge in

 areal recharge zone 1, in feet.

 Head change computed by 

 subtracting the 2006 simulated 

 head in the calibrated model

 from the 2006 simulated head in the 

 model with a 10-percent increase

 in recharge in areal recharge

 zone 1.

Observation point

greater than 8

greater than 6 to 8

greater than 4 to 6

greater than 2 to 4

 0 to 2

greater than 0 to 2

greater than 2 to 4

greater than 4 to 6

greater than 6 to 8

INCREASE DECREASE
Effects of Projected Groundwater Use 87

The prediction-period sensitivity test consisted of 

increasing each model parameter by 10 percent while holding 

the other parameters constant and evaluating the simulated 

head change at the end of the prediction period. Predictive 

simulation scenario 7, discussed in more detail in the Low 

and High Population Growth with New Industrial Wells 

section of the report, was used to evaluate the sensitivity of 

the hydraulic parameters on the model predicted results. At 

the end of the simulation period on day 365 in the year 2030, 

the head distribution was compared between the calibrated 

model results and the model results with adjusted parameters. 

The differences were computed at the 2,076 observation 

points by subtracting the head obtained from the adjusted 

parameter value model from the head obtained from the 

calibrated model. The RMSE of these differences was 

computed and tabled by rank (table 13). Although the ranks 

of the hydraulic parameters are not identical, the top 10 most 

sensitive parameters for model calibration are also the top 10 

parameters for model prediction. Relative to the predictive 

simulation results, the model is most sensitive to the horizontal 

hydraulic conductivity of the Ozark aquifer in zones 1 and 6 

(fig. 30), to the specific storage of the Ozark aquifer in zone 4 

(fig. 30), to the recharge in zone 1 (fig. 19), and to the vertical 

hydraulic conductivity of zone 3 in the Ozark confining unit 

(fig. 29). The horizontal hydraulic conductivity of zone 6 in 

the Ozark aquifer (fig. 30) substantially moved up in rank 

relative to the calibration period sensitivity rank. This is an 

indication that it takes greater simulation time and more stress 

on the system to reveal the importance of this parameter. A 

possible implication of this could be that inaccuracy in these 

parameters could cause larger uncertainty in the simulated 

head distribution as the length of the predictive simulation 

is increased. Distribution of the simulated head change after 

increasing the horizontal hydraulic conductivity in the Ozark 

aquifer zone 1 (OZHK1, table 13; OZA1, fig. 30) computed 

at the end of the prediction period in 2030 is presented in 

figure 47. After the adjustment of the horizontal hydraulic 

conductivity in the Ozark aquifer zone 1, the head in layer 3 

(fig. 47; LAYER 3) increased in the vicinity of pumping wells 

in zone 1 of the Ozark aquifer in central Greene County and 

decreased in the northeastern, southwestern, and south-central 

part of the model area. Distribution of the simulated head 

change computed at the end of 2030 (fig. 47) is similar to the 

distribution computed at the end of the calibration period in 

2006 (fig. 45), however, the magnitude of the change is larger 

at the end of 2030. 

Effects of Projected Groundwater Use

The increase in groundwater demand from future 

population growth and the construction and pumping of new 

high-capacity wells in the model area will increase the stress 

on the Ozark aquifer. Seven hypothetical scenarios, provided 

to the USGS by the Greene County Resource Management 

Department in consultation with area communities, were 

investigated using the calibrated model to assess changes in 

the potentiometric surface in the Ozark aquifer because of 

future stress increases (table 14). Each hypothetical scenario 

was simulated from the year 2007 to 2030.

Comparison of the low and high population growth 

rate in scenarios 2 with 4, 3 with 5, and 6 with 7 (table 14) 

indicates that there is not a large enough difference in the 

growth rates to cause substantial head change between the 

two. The largest changes occur to the potentiometric surface 

when new high capacity wells are added to the model 

(scenarios 6 and 7). The changes are large at the model cells 

with the new wells, but diminish relatively quickly as the 

distance from the well increases. Little change in drawdown 

was predicted in Nixa, Ozark, and Republic because of the 

installation of the new industrial wells (relative to scenarios 2 

through 5). 

Projected Groundwater Use

Projected groundwater use was estimated using a low rate 

and a high rate of projected population growth (Greene County 

Resource Management Department, written commun., 2008) 

for 12 communities, the unincorporated part of Greene County, 

and the rural domestic users (table 15). The percentages shown 

in table 15 were applied directly to the 2006 pumpage rates 

reported for each community or group for the appropriate 

scenario in table 14. For both low and high growth scenarios, 

each of the 12 communities and the unincorporated part of 

Greene County had a different rate of growth. The same rate 

of growth was used for the unincorporated part of Greene 

County and the rural domestic users. Future population growth 

for all communities and the unincorporated part of Greene 

County, except Battlefield, was based on linear growth rates 

established between the years 2000 and 2007 (Greene County 

Resource Management Department, written commun., 2008). 

Future population growth for the community of Battlefield 

was based on linear growth rates of population between 1980 
88 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 47. Simulated head change in layer 1 and layer 3 following a 10-percent increase in horizontal hydraulic conductivity in zone 1 

of the Ozark aquifer (OZHK1, table 13; OZA1, fig. 30) computed at the end of the prediction period in 2030 for scenario 7.

0 10 20 MILES 0 10 20 KILOMETERS

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

93°30' 93°00'

37°30'

37°00'

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

93°30' 93°00'

37°30'

37°00'

0 10 20 MILES

0 10 20 KILOMETERS

LAYER 1

LAYER 3

EXPLANATION

River

Simulated head change in layer 1

 and layer 3 following a 10-

 percent increase in horizontal

 hydraulic conductivity in zone 1

 of the Ozark aquifer, in feet.

 Head change computed by 

 subtracting the 2030 simulated 

 head in the calibrated model

 from the 2030 simulated head in the 

 model with a 10-percent increase

 in horizontal hydraulic conductivity

 in zone 1 of the Ozark aquifer.

Observation point

greater than 20

greater than 16 to 20

greater than 12 to 16

greater than 8 to 12

greater than 4 to 8

greater than 0 to 4

0 to 4

greater than 4 to 8

INCREASE DECREASE
Model Calibration 89

Table 14. Hypothetical pumping scenarios 2007 to 2030.[ft/d, foot per day; ft3/d, cubic foot per day; ft, foot]

Predictive simulation period 

2007 to 2030

Hypothetical 

scenario number

Future scenario

conditions

Recharge rate

(ft/d)

Pumping Rate

in 2030 

(ft3/d)

Maximum head 

decline at 

Springfield 

(ft)

Head decline in 

Nixa, Ozark, and 

Republic, area 

(ft) Summary of results

1 Water use fixed

at 2006 rate

2.59x10-4 4,330,177 61.5 15 to 45 Continued decline in the Springfield, 

Nixa, Ozark, and Republic area

2 Low growth rate;

Drought 2010 to 2013

2.59x10-4 (1.45x10-4 

drought conditions)

 7,109,711 203.4 greater than 100 Continued decline in the Springfield, 

Nixa, Ozark, and Republic area

3 Low growth rate;

Drought 2027 to 2030

2.59x10-4 (1.45x10-4

drought conditions)

 7,109,711 203.9 greater than 100 Simulated head lower than scenario 2 

where Ozark aquifer is exposed; similar to scenario 2 elsewhere

4 High growth rate; 

Drought 2010 to 2013

2.59x10-4 (1.45x10-4

drought conditions)

 7,220,436 206.9 greater than 100 Simulated head lower than scenario 2 in 

the vicinity of the cities of Springfield, Nixa, Ozark, and Republic; similar to scenario 2 elsewhere

5 High growth rate; 

Drought 2027 to 2030

2.59x10-4 (1.45x10-4

drought conditions)

 7,220,436 207.3 greater than 100 Simulated head lower than scenario 4 

where Ozark aquifer is exposed; similar to scenario 4 elsewhere

6 Low growth rate; New 

industrial wells

2.59x10-4 7,500,601 641.0 greater than 100 Simulated head similar to scenarios 

2 through 5 in the vicinity of the cities of Republic, Ozark, and Nixa; simulated head lower near the new industrial wells; potentiometric surface 10 to 40 ft lower in Rogersville and Fordland than scenarios 2 through 5; simulated head higher where Ozark aquifer is exposed relative to simulated head in scenario 3 and scenario 5

7 High growth rate; New 

industrial wells

2.59x10-4 7,582,583 648.2 greater than 100 Similar results to scenario 6, but greater 

decline at the new industrial wells
90 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

and 2007 (Greene County Resource Management Department, 

written commun., 2008). A graph showing the population 

projections using the high population growth rate for 11 

communities is shown in figure 48. Population for Springfield 

and the unincorporated part of Greene County were omitted 

for clarity from figure 48. The slope of the lines on figure 48 

indicates the rate of population growth per year for each 

community. Future pumpage rates data were computed 

annually from 2007 to 2030 based on the growth rate and 

the 2006 reported pumpage rates for each well. Low growth 

rates ranged from 0.215 percent per year in Springfield to 

6.997 percent per year in Rogersville, and total growth from 

2006 to 2030 at the low growth rate ranged from 5.2 percent 

in Springfield to 167.9 percent in Rogersville (table 15). High 

growth rates ranged from 0.236 percent per year in Springfield 

to 7.345 percent per year in Rogersville, and total growth from 

2006 to 2030 at the high growth rate ranged from 5.7 percent 

in Springfield to 176.3 percent in Rogersville (table 15). 

Because pumpage rates for wells can increase 

dramatically in future projections, future pumpage rates for 

wells may exceed the actual capacity of an individual well. 

This is not a realistic situation because water managers could 

install new wells or redistribute pumping within their water 

system. The problem of future pumpage rates exceeding 

the capacity of the well becomes more likely the further 

into the future the estimates are made. In an effort to make 

the pumpage rates more realistic for individual wells and 

water systems, major groundwater users in the model area 

were asked to provide an estimate of what percent of the 

total capacity of each well in their system was being used 

in 2006. The communities of Marshfield, Nixa, Ozark, 

Republic, Springfield, Strafford, and Willard, reported this 

information for the wells in their water systems (table 15). The 

groundwater use in these communities’ 41 wells represents 

approximately 40 percent of the groundwater use in the 

model area in 2006. In addition, major groundwater users 

in the model area were asked to provide information about 

when existing wells were likely to be removed from service 

and when and where new wells were planned to be drilled 

and operated (fig. 25). The communities of Nixa, Ozark, 

Republic, and Springfield reported plans to decommission old 

wells, install new wells, or both. When building the future 

groundwater-use data set, the computed future pumpage rate, 

for wells that had current (2006) capacity data reported, was 

compared to the reported capacity. If the computed future 

pumpage rate exceeded the reported capacity of the well, the 

excess was redistributed to other wells in the community’s 

system including new wells when they became available. 

Table 15. Projected population growth per year (in percent of 2006 population) and number of wells in 2006 per percentage range of 

total operating capacity.

[—, no data]

Community or group Growth rate (in percent of 

2006 population)1

Total percent growth from 

2006 to 2030 

Number of wells in 2006 per percentage range

of total operating capacity

Low High Low High 0-25 25-50 50-75 75-100

Ash Grove 1.089 1.124 26.1 27.0 — — — —

Battlefield 2.300 2.919 55.2 70.1 — — — —

Fair Grove 2.776 2.875 66.6 69.0 — — — —

Greene County

(Unincorporated)

2.531 2.578 60.7 61.9 — — — —

Marshfield 2.752 2.782 66.1 66.8 0 3 0 0

Nixa 4.995 5.140 119.9 123.3 7 0 0 0

Ozark 6.251 6.317 150.0 151.6 12 1 0 0

Republic 4.891 5.017 117.4 120.4 1 2 0 1

Rogersville 6.997 7.345 167.9 176.3 — — — —

Springfield .215 .236 5.2 5.7 2 4 1 0

Strafford 1.823 1.945 43.8 46.7 1 2 0 0

Walnut Grove .765 .848 18.4 20.4 — — — —

Willard .804 .862 19.3 20.7 0 0 2 2

Rural domestic use 2.531 2.578 60.7 61.9 — — — —

1

 Source: Greene County Resource Management Department, written commun., 2008
Effects of Projected Groundwater Use 91

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

2005 2010 2015 2020 2025 2030

POPULATION

YEAR

Ozark

Nixa 

Republic

Marshfield

Rogersville

Battlefield

Willard

Strafford

Fair Grove

Ash Grove

Walnut Grove

EXPLANATION

For each well in a community’s water system, Ozark for 

example, groundwater use in excess of the reported capacity 

of an individual well was added to the well in the system with 

the lowest pumpage rate. The wells in the system were then 

reevaluated to determine if any wells exceeded the reported 

capacity, and the process was repeated. If it was determined 

that all wells in the system were at or exceeded their reported 

capacity, then no further redistribution was performed and 

future pumpage rate in the wells was allowed to increase 

at the specified rate beyond the reported capacity. Future 

groundwater use in wells that had no reported capacity was 

allowed to increase at the specified rate. In the future pumpage 

rate computations, wells that were specified by major 

groundwater users to be decommissioned were turned off, and 

those specified to be installed were turned on in the specified 

year. For the seven communities that reported well capacity 

information, future groundwater use in 2030 did not exceed 

the system capacity in any of the communities; however, 10 of 

the 41 wells belonging to those communities were computed 

to be at their reported capacity in 2030.

Continued Pumpage at the 2006 Rate

To provide a frame of reference for change because 

of drought, population growth, and installation of new 

industrial wells, hypothetical scenario 1 was developed 

to show the effects of continued pumpage at the 2006 

rate. Beginning in 2009, precipitation was assumed to 

be constant at a rate equal to the 1971–2000 mean of 

44.97 in/yr (recharge = 2.59x10-4 ft/d), and pumping was 

Figure 48. Estimated high growth population change from 2006 to 2030 for selected communities in the model area (Greene County 

Resource Management Department, written commun., 2008).
92 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

held at a constant equal to the 2006 rate. Figure 49 shows the 

resulting head distribution at the end of the simulation in 2030 

for hypothetical scenario 1. The simulation indicates that the 

potentiometric surface in the Springfield area continues to 

decline (fig. 49) with a maximum drawdown obtained from the 

model of 61.5 ft relative to the 2006 level occurring at major 

pumping centers. Drawdown in the Nixa, Ozark, and Republic 

areas could range from 15 to 45 ft if pumping were continued 

at 2006 rates. 

Drought Effects and Low Population Growth

To simulate the effects that low population growth 

and drought conditions could have on the future 

head distribution in the Ozark aquifer, hypothetical 

scenario 2 was developed. The mean value of recharge 

(table 5; precipitation = 44.97 in/yr; recharge = 2.59x10-4 ft/d) 

was used for 2009. The drought conditions (table 5; 

precipitation = 25.21 in/yr; recharge = 1.45x10-4 ft/d) were 

simulated at the beginning of the future simulation period for 

a 4-year period beginning in 2010 and continuing through 

2013. Beginning in 2014 and continuing through the end 

of the simulation, the mean value of recharge was used. 

Groundwater-use increases during the drought period do 

not account for extra increases in groundwater use, such as 

lawn watering, as a result of the drought. Figure 50 shows 

the resulting head distribution at the end of the simulation in 

2030 for hypothetical scenario 2. Population growth increases 

groundwater demand and causes larger potentiometric-surface 

declines around the major pumping centers in the model 

area. Maximum declines continue to be in the Springfield 

area (203.4 ft obtained from the model); however, maximum 

groundwater declines in Nixa, Ozark, and Republic, relative to 

the 2006 levels, are greater than 100 ft (fig. 50). 

Hypothetical scenario 3 investigates the effects of a 

4-year drought at the end of the simulation in combination 

with a low population growth rate. The drought conditions 

(table 5; precipitation = 25.21 in/yr; recharge = 1.45x10-4 ft/d) 

were simulated at the end of the future simulation period for 

a 4-year period beginning in 2027 and continuing through 

2030. Groundwater-use increases during the drought period 

do not account for extra increases in groundwater use, such as 

lawn watering, as a result of the drought. Beginning in 2009 

and continuing through 2026, the mean value of recharge 

was used. Figure 51 shows the resulting head distribution at 

the end of the simulation in 2030 for hypothetical scenario 3. 

The head distribution in the Ozark aquifer of hypothetical 

scenario 3 is similar to the head distribution for hypothetical 

scenario 2 in the vicinity of the cities of Nixa, Ozark, 

Republic, and Springfield, and the maximum drawdown 

of 203.9 ft obtained from the model, which occurred in 

Springfield was nearly identical. Simulated head is higher in 

the northeastern and southeastern part of the model area in 

scenario 2 than in scenario 3 where the Ozark aquifer 

is exposed. 

Drought Effects and High Population Growth

Hypothetical scenarios 4 and 5 were developed to 

examine the effects of high population growth rates combined 

with drought conditions at the beginning (scenario 4) 

and end (scenario 5) of the simulation period. Scenario 4 

(fig. 52) was similar to scenario 2 with the mean value of 

recharge (2.59x10-4 ft/d) used for 2009, drought conditions 

(1.45x10-4 ft/d) between 2010 and 2013, and mean recharge 

from 2014 to 2030. Groundwater-use increases during 

the drought period do not account for extra increases in 

groundwater use, such as lawn watering, as a result of the 

drought. Scenario 5 (fig. 53) was similar to scenario 3 with 

the mean value of recharge used between 2009 and 2026 

and drought conditions from 2027 to 2030. Maximum 

declines obtained from the model in scenario 4 (206.9 ft) and 

5 (207.3 ft) occur in the Springfield area; however, maximum 

groundwater declines in Nixa, Ozark, and Republic, relative 

to the 2006 levels, are greater than 100 ft (figs. 52 and 53). 

Similar to scenarios 2 and 3, the drought conditions at 

the end of the simulation period for scenario 5 caused the 

potentiometric surface to be lower than the potentiometric 

surface in scenario 4 where the Ozark aquifer is exposed 

(figs. 52 and 53).

Simulated head is lower and drawdown areas are 

expanded somewhat under the high population growth rate 

scenarios (4 and 5) when compared to the low population 

growth rate scenarios (2 and 3) under both drought simulation 

conditions. Both high growth rate scenarios (4 and 5) have 

lower potentiometric surfaces than either low growth rate 

scenario (2 and 3) in the vicinity of the cities of Nixa, Ozark, 

Republic, and Springfield.

Low and High Population Growth with New 

Industrial Wells

Scenarios 6 and 7 were developed to investigate 

the effect that proposed new industrial wells could have 

on the potentiometric surface in the Ozark aquifer. Two 

industrial wells pumping continuously from 2010 through 

2030 were added to the simulation. The pumping rate 

from the two wells began at approximately 173,262 ft3/d 

(approximately 900 gal/min) and was increased at the 

same rate as the Greene County unincorporated wells 

for the low and high population growth-rate scenarios. 

In 2030 the two wells were pumping 252,460 ft3/d 

(approximately 1,311 gal/min) under the low growth rate 

conditions (scenario 6) and 254,820 ft3/d (approximately 

1,324 gal/min) under the high growth rate conditions 

(scenario 7). The locations of these wells (fig. 25) were 

provided to the USGS by Greene County Resource 

Management Department (written commun., 2008). One 

well was located in the downtown area of Springfield and 

the second was located approximately 3.5 miles east of 
Effects of Projected Groundwater Use 93

Figure 49. Simulated head at the end of 2030 in layer 3 and difference in simulated head between 2006 and 2030 (2006 minus 2030) for 

hypothetical scenario 1—groundwater use fixed at 2006 rate.

0

50

0

50

0

30

0

20

0

10

40

0

Springfield

Ozark

Nixa

Republic

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

93°30' 93°00'

37°30'

37°00'

1,350

1,100

1,050

1,250

1,200

1,000

800

1,150

1,100

950

1,050

1,300

950

850

900

850

900

1,250

950

1,400

1,200

1,150

900

1,000

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS

LACLEDE

WEBSTER

DOUGLAS

93°30' 93°00'

37°30'

37°00'

0 10 20 MILES

0 10 20 KILOMETERS

Line of equal simulated head, in feet—

 Contour interval 50 feet. 

 Datum is National Geodetic Vertical

 Datum 1929.

900

Difference contour—

 Shows the difference between

 simulated head in 2006 and 

 simulated head in 2030

 (2006 minus 2030). Contour

 interval 50 feet.

River

20

Incorporated area

EXPLANATION

1,600

200

400

600

800

1,000

1,200

1,400

Simulated head in 2030, in feet
94 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 50. Simulated head at the end of 2030 in layer 3 and difference in simulated head between 2006 and 2030 (2006 minus 2030) for 

hypothetical scenario 2—low groundwater-use growth rate and 4-year drought from 2010 to 2013.

Springfield

Ozark

Nixa

Republic

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

80

140

0

100

0

0

80

60

40

20

120

0

40

100

93°30' 93°00'

37°30'

37°00'

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

850

1,300

1,250

900

1,200

1,150

1,100

1,000

950

1,050

1,050

800

850

900

750

900

1,250

950

800

1,400

1,200

1,150

1,000

1,350

1,100

93°30' 93°00'

37°30'

37°00'

0 10 20 MILES

0 10 20 KILOMETERS

Line of equal simulated head, in feet—

 Contour interval 50 feet. 

 Datum is National Geodetic Vertical

 Datum 1929.

900

Difference contour—

 Shows the difference between

 simulated head in 2006 and 

 simulated head in 2030

 (2006 minus 2030). Contour

 interval 50 feet.

River

20

Incorporated area

EXPLANATION

1,600

200

400

600

800

1,000

1,200

1,400

Simulated head in 2030, in feet
Effects of Projected Groundwater Use 95

Figure 51. Simulated head at the end of 2030 in layer 3 and difference in simulated head between 2006 and 2030 (2006 minus 2030) for 

hypothetical scenario 3—low groundwater-use growth rate and 4-year drought from 2027 to 2030.

Springfield

Ozark

Nixa

Republic

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

80

100

140

120

100

0

80

60

40

20

20

40

93°30' 93°00'

37°30'

37°00'

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

850

1,300

1,250

900

1,200

1,100

1,150

1,000

950

1,050

1,050

800

850

900

750

900

1,250

950

800

1,400

1,200

1,150

1,000

1,350

1,100

93°30' 93°00'

37°30'

37°00'

0 10 20 MILES

0 10 20 KILOMETERS

Line of equal simulated head, in feet—

 Contour interval 50 feet. 

 Datum is National Geodetic Vertical

 Datum 1929.

900

Difference contour—

 Shows the difference between

 simulated head in 2006 and 

 simulated head in 2030

 (2006 minus 2030). Contour

 interval 50 feet.

River

20

Incorporated area

EXPLANATION

1,600

200

400

600

800

1,000

1,200

1,400

Simulated head in 2030, in feet
96 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 52. Simulated head at the end of 2030 in layer 3 and difference in simulated head between 2006 and 2030 (2006 minus 2030) for 

hypothetical scenario 4—high groundwater-use growth rate and 4-year drought from 2010 to 2013.

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

Springfield

Ozark

Nixa

Republic

100

140

0

100

0

0

80

60

40

20

120

0

40

80

93°30' 93°00'

37°30'

37°00'

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

850

1,300

1,250

900

1,200

1,150

1,100

1,000

950

1,050

1,050

800

850

700

900

750

900

1,250

950

800

1,400

1,200

1,150

1,000

1,350

1,100

93°30' 93°00'

37°30'

37°00'

0 10 20 MILES

0 10 20 KILOMETERS

Line of equal simulated head, in feet—

 Contour interval 50 feet. 

 Datum is National Geodetic Vertical

 Datum 1929.

900

Difference contour—

 Shows the difference between

 simulated head in 2006 and 

 simulated head in 2030

 (2006 minus 2030). Contour

 interval 50 feet.

River

20

Incorporated area

EXPLANATION

1,600

200

400

600

800

1,000

1,200

1,400

Simulated head in 2030, in feet
Effects of Projected Groundwater Use 97

Figure 53. Simulated head at the end of 2030 in layer 3 and difference in simulated head between 2006 and 2030 (2006 minus 2030) for 

hypothetical scenario 5—high groundwater-use growth rate and 4-year drought from 2027 to 2030.

Springfield

Ozark

Nixa

Republic

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

80

100

20

120

100

0

80

60

40

20

140

4

100

0

93°30' 93°00'

37°30'

37°00'

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

850

1,300

1,250

900

1,200

1,100

1,150

1,000

950

1,050

1,050

800

850

700

900

750

900

1,250

950

800

1,400

1,200

1,150

1,000

1,350

1,100

93°30' 93°00'

37°30'

37°00'

0 10 20 MILES

0 10 20 KILOMETERS

Line of equal simulated head, in feet—

 Contour interval 50 feet. 

 Datum is National Geodetic Vertical

 Datum 1929.

900

Difference contour—

 Shows the difference between

 simulated head in 2006 and 

 simulated head in 2030

 (2006 minus 2030). Contour

 interval 50 feet.

River

20

Incorporated area

EXPLANATION

1,600

200

400

600

800

1,000

1,200

1,400

Simulated head in 2030, in feet
98 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Rogersville (fig. 2). Mean recharge (2.59x10-4 ft/d) was used 

for scenarios 6 and 7 between 2009 and 2030.

The lowest simulated head in scenario 6 (fig. 54) 

occurred at the new industrial well located in Springfield and 

the head was less than 200 ft (examination of the model cell 

containing the well determined the head to be approximately 

189 ft). The approximate altitude of the bottom of the Ozark 

aquifer at that location is at -280 ft below NGVD 29 and 

the total thickness of the aquifer is approximately 1,300 ft. 

There is approximately 469 ft of saturated Ozark aquifer at 

the location of the new industrial well located in Springfield 

at the end of 2030. Both new industrial wells produce a 

relatively steep cone of depression. The maximum drawdown 

in scenario 6 relative to the 2006 levels also occurred at the 

new industrial well located in Springfield and was 641.0 ft 

lower than the 2006 level. There is a small, 5 ft, potentiometric 

surface increase, relative to 2006 levels in the northeastern 

and southeastern part of the model area. This is most likely 

because the aquifer is recovering from the relatively low 

precipitation that occurred in 2005 and 2006. 

Simulated head for scenario 7 (fig. 55) was very 

similar to scenario 6 with a minimum altitude below 250 ft 

occurring at the new industrial well located in Springfield. 

Examination of the model output at the cell containing the 

well revealed the head to be approximately 182 ft. The 

maximum drawdown in scenario 7, relative to 2006 levels, 

also occurred at the new industrial well located in Springfield 

and was 648.2 ft lower than the 2006 level. The potentiometric 

surface in scenario 7 increases similarly in both magnitude and 

location as scenario 6.

Scenarios 6 and 7 with new industrial wells produce 

a relatively steep cone of depression around the new wells. 

The difference between scenario 3 and scenario 6 is shown in 

figure 56. The potentiometric surface is higher in scenario 6 

when compared to scenario 3 where the Ozark aquifer is 

exposed, most likely because of the drought conditions 

simulated in scenario 3. It is also evident that the majority 

of the change between the two scenarios occurs at the 

new industrial wells. Simulated head differences between 

scenario 3 and scenario 6 that are greater than 50 ft are 

confined to the areas within approximately 2.5 miles of the 

new wells. The potentiometric surface is from 10 to 40 ft 

lower in Rogersville and Fordland in scenario 6 relative 

to scenario 3 because of drawdown associated with one 

of the new industrial wells. Under scenario 6 the cities of 

Nixa, Ozark, and Republic will experience little additional 

drawdown when compared to scenario 3 drawdown. 

Model Limitations

By definition, a model is a simplification of reality, 

and therefore, a groundwater model approximates actual 

conditions. The flow system is greatly simplified, and the 

accuracy of the model results depends on the accuracy and 

completeness of the input data. The following limitations 

need to be considered when interpreting the model results 

presented in this report. The MODFLOW software simulates 

groundwater flow as porous media flow; however, karst 

features present in the model area as well as the lithology 

of the aquifer material indicate flow to be, at least partially, 

conduit flow along bedding planes, joints, and fractures. Lack 

of data on base flow to rivers and springs and few hydraulic 

property tests of the hydrogeologic units in the model area 

result in poorly constrained values of hydraulic conductivity, 

specific storage, and specific yield. Well pumping rates used 

in the model were annual total values and were applied 

uniformly throughout the stress period (year), however, 

pumping rates are not uniform and this could add uncertainty 

to the results. Recharge was applied uniformly throughout 

a stress period (year) and distributed over the model area 

based on land slope; however, recharge is not uniform either 

temporally or spatially. The relation between precipitation 

and recharge is not likely to be linear as it was assumed in 

this model. Model cells were 1,000 ft by 1,000 ft so landsurface altitudes and altitudes of rivers had to be averaged 

over a model cell, which is less exact in areas with larger 

relief. When water discharges to a spring, the groundwater 

model removes that discharge and it cannot reenter the system. 

Position of springs and pumping wells could not be precisely 

located because of the cell size. Because of the cell size, the 

model is of limited use for detailed groundwater-flow analysis 

near a single well. Discretization of the hydrogeologic units 

in the model combined several units into layers 1 and 2. 

This caused difficulty interpreting the head in layers 1 and 2, 

particularly in model cells that combined hydrogeologic units. 

General-head boundaries, rivers, and drains (springs) require 

the assumption that the specified head does not vary during the 

entire simulation, and that the conductance value governing 

the interaction of the groundwater with the boundary is 

known. Neither assumption is likely to be true. Little is known 

about the hydraulic properties of the St. Francois confining 

unit and the head distribution in the underlying St. Francois 

aquifer, and as a result, assumptions of these values are likely 

to be in error.

Many faults are evident at the land surface in the model 

area and likely continue through the confining unit, but it is 

unknown whether the faults are flow conduits or barriers. 

The assumption of homogeneity of hydraulic properties 

in cells and zones can cause inaccuracies. Pumpage from 

the Springfield Plateau aquifer (although likely small) was 

ignored in the model. Drawdown in the Ozark aquifer near 

Springfield has caused the aquifer to be unconfined in that 

area. Numerical instability in the model necessitated modeling 

layer 2 and layer 3 as confined, which could cause future 

potentiometric-surface predictions to be in error in this area. 

The potentiometric-surface predictions are likely too high 

where the Ozark aquifer is unconfined or becomes unconfined 

as the simulation progresses. Predictive simulations are based 

on a predefined set of conditions that are merely estimates 

of what is expected to happen in the future. There is great 
Model Limitations 99

Figure 54. Simulated head at the end of 2030 in layer 3 and difference in simulated head between 2006 and 2030 (2006 minus 2030) for 

hypothetical scenario 6—low groundwater-use growth rate and two new industrial wells.

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

Springfield

Ozark

Nixa

Republic Rogersville

100

0

150

50 100

0

0

50

200

0

93°30' 93°00'

37°30'

37°00'

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

850

1,050

1,300

900

1,250

1,150

1,200

1,100

1,000

950

1,050

800

850

650

900

700

900

750

1,250

950

1,400

1,200

800

1,150

1,000

1,350

1,100

93°30' 93°00'

37°30'

37°00'

0 10 20 MILES

0 10 20 KILOMETERS

Line of equal simulated head, in feet—

 Contour interval 50 feet. 

 Datum is National Geodetic Vertical

 Datum 1929.

900

Difference contour—

 Shows the difference between

 simulated head in 2006 and 

 simulated head in 2030

 (2006 minus 2030). Contour

 interval 50 feet.

River

20

Incorporated area

EXPLANATION

1,600

200

400

600

800

1,000

1,200

1,400

Simulated head in 2030, in feet
100 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

Figure 55. Simulated head at the end of 2030 in layer 3 and difference in simulated head between 2006 and 2030 (2006 minus 2030) for 

hypothetical scenario 7—high groundwater-use growth rate and two new industrial wells.

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS LACLEDE

WEBSTER

DOUGLAS

Springfield

Ozark

Nixa

Republic

Rogersville 100

250

0

100

200

50

100

0

0

50

150

0

100

93°30' 93°00'

37°30'

37°00'

BARRY

LAWRENCE

DADE

POLK

GREENE

CHRISTIAN

STONE

DALLAS

LACLEDE

WEBSTER

DOUGLAS

1,050

1,300

1,250

900

1,150

1,200

1,100

1,000

950

1,050

850

800

850

650

900

700

900

750

1,250

950

1,400

1,200

800

1,150

1,000

1,350

1,100

93°30' 93°00'

37°30'

37°00'

0 10 20 MILES

0 10 20 KILOMETERS

Line of equal simulated head, in feet—

 Contour interval 50 feet. 

 Datum is National Geodetic Vertical

 Datum 1929.

Difference contour—

 Shows the difference between

 simulated head in 2006 and 

 simulated head in 2030

 (2006 minus 2030). Contour

 interval 50 feet.

River

20

Incorporated area

EXPLANATION

1,600

200

400

600

800

1,000

1,200

1,400

Simulated head in 2030, in feet

900
Model Limitations 101Figure 56. Difference in simulated head in 2030 between scenario 3 and scenario 6.

Springfield

Ozark

Nixa

Willard

Aurora

Republic

Marshfield

Brookline

Highlandville

Fair Grove

Seymour

Strafford

Crane

Conway

Battlefield

Sparta Marionville

Ash Grove

Dadeville

Billings

Rogersville

Diggins

Clever

Fordland

Spokane

Pleasant Hope

Hurley

Niangua

Everton

Fremont Hills

Walnut Grove

Morrisville

Mount Vernon

Halltown

Verona

Finley Creek

Sac River

James River

Turnback Creek

Swan Creek

Beaver Creek

Bull Creek Crane Creek

Wilsons Creek

Little Beaver Creek

Turkey Creek

Pierson Creek

Niangua River

Honey Creek

Osage Fork

Gasconade River

Little Sac River

James River

Pomme de

Terre River Stockton Lake

Fellows

Lake McDaniel Lake

Lake

Springfield

GREENE

WEBSTER

CHRISTIAN

POLK

DADE

STONE

LAWRENCE

DOUGLAS

DALLAS

BARRY

LACLEDE

100

01 0

0

75

75

05

50

0

25

25

Base from U.S. Geological Survey digital data, 1:100,000, 1995and U.S. Census TIGER/line files, 2003Universal Transverse Mercator projection, zone 15

93°00' 93°30'

37°30'37°00'

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

Difference contour

—

 Shows the difference between the simulated head in scenario 3  and the simulated head in  scenario 6 (scenario 3 minus  scenario 6). Contour interval  25 feet

20

Incorporated area
102 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

uncertainty in these estimates, and as a result, the predictions 

from the model also have great uncertainty. The best use of the 

predictions is for comparison between future conditions. 

Summary and Conclusions

Groundwater use from the Ozark aquifer in and around 

Greene County, Missouri, has increased since it was first 

used as a drinking-water source as early as 1907. Historical 

groundwater pumping from the Ozark aquifer caused a cone 

of depression to form beneath Springfield. Periods of rapid 

growth in the 1970s and 1980s coupled with a growing 

cone of depression led water managers in Springfield to 

seek an alternate source of water to meet their future needs. 

The demand for groundwater in the area was reduced when 

Springfield completed a pipeline in 1996 to bring water from 

Stockton Lake to the city. Even though Springfield reduced its 

dependence on groundwater, all other residential, commercial, 

industrial, and municipal users in the region rely exclusively 

on groundwater to meet their water needs. Groundwater-level 

measurements made in 2006–07 indicated that the cone of 

depression beneath Springfield has continued to expand and 

deepen. A groundwater-flow model was developed by the 

U.S. Geological survey (USGS) in cooperation with Greene 

County, Missouri, the U.S. Army Corps of Engineers, and the 

Missouri Department of Natural Resources to assess the effect 

that increased groundwater demand is having on the long-term 

availability of groundwater in Greene County, Missouri, and 

the surrounding area. The purpose of this report is to document 

the groundwater-flow model that characterizes groundwater 

flow within a part of the Ozark Plateaus aquifer system in the 

vicinity of Greene County, Missouri.

The three hydrogeologic units that were represented in 

the model were, from top to bottom, the Springfield Plateau 

aquifer, the Ozark confining unit, and the Ozark aquifer. The 

Springfield Plateau aquifer is composed of coarse crystalline, 

cherty limestone, and wells in the aquifer yield only sufficient 

amounts of water for domestic and stock use. The Ozark 

confining unit is composed of fine-grained limestone, siltstone, 

and shale and confines the underlying Ozark aquifer. The 

Ozark aquifer is composed of dolomite and sandstone, and is 

the primary aquifer for most of southern Missouri. Wells open 

to the entire Ozark aquifer typically yield 1,000 gallons per 

minute, which makes this aquifer suitable for industrial and 

municipal needs. The Springfield Plateau aquifer is exposed 

at the surface over much of the model area. The Ozark 

confining unit is exposed in narrow bands between outcrops 

of the Springfield Plateau aquifer and the Ozark aquifer. The 

Ozark aquifer is exposed at the surface in the northeastern 

and southeastern parts of the model area and along some river 

valleys. Karst features such as sinkholes, springs, caves, and 

losing streams are present in both aquifers, but the majority of 

these features occur in the Springfield Plateau aquifer.

A part of the precipitation that falls on the exposed 

aquifers in the study area recharges the groundwater by 

infiltration. Groundwater generally flows from the recharge 

areas of the aquifers in the uplands where they are exposed 

to the discharge areas along rivers and springs. Groundwater 

may be captured along its flow path by pumping wells, and 

groundwater flow occurs laterally both into and out of the 

study area. The gradient is generally downward from the 

Springfield Plateau aquifer through the confining unit and into 

the Ozark aquifer. Groundwater can flow vertically through 

the bottom of the Ozark aquifer. Karst flow, particularly in the 

Springfield Plateau aquifer, can move large quantities of water 

through the system in a relatively short time. Rivers in the area 

include gaining and losing reaches. 

Tops and bottoms of the hydrogeologic units were 

mapped and discretized into the model grid. The model was 

divided into three layers with the layer boundaries crossing 

hydrogeologic unit boundaries in some areas. The area 

was divided into a regularly spaced grid of 253 rows and 

316 columns with 1,000 feet by 1,000 feet cells. Composite 

hydraulic properties for the model were computed from the 

hydraulic properties of the individual hydrogeologic units 

for each cell containing multiple hydrogeologic units. A 

groundwater model with annual stress periods was developed 

using a transient calibration period from 1987 to 2006 and a 

prediction period from 2007 to 2030. 

Recharge in the model was estimated independently 

using water-level data from a long-term monitoring well 

using the water-table fluctuations method. Rivers and springs 

were used as boundary conditions in the model. Rivers acted 

as both recharge and discharge points for the groundwater, 

whereas the springs served to locally constrain head in layer 1 

of the model. Groundwater flow laterally through the model 

boundaries, leakage through the bottom of the Ozark aquifer, 

and flow into and out of lakes was simulated with generalhead boundaries in the model.

Annual precipitation data were compiled for the model 

area for use in estimating the model recharge and ranged 

from 25.21 inches in 1953 to 62.45 inches in 1927. Areal 

recharge was calculated as approximately 2.53 percent of the 

annual precipitation and distributed based on land slope and 

adjusted in the Springfield area based on impervious surface. 

The mean annual precipitation for the period 1971–2000 

was 44.97 inches in the model area, which calculates to 

2.59x10-4 feet per day of recharge in the model. Annual 

pumpage data were estimated prior to 1962 and from 1962 to 

2006, were collected from multiple sources including: USGS, 

Missouri Department of Natural Resources major water user 

database, Missouri Department of Natural Resources public 

water-supply database, Greene County, and reported use from 

groundwater users. Pumpage rates in the model area increased 

from 1,093,268 cubic feet per day in 1962 to 2,693,423 cubic 

feet per day in 1987 to 4,330,177 cubic feet per day in 2006. 

There were relatively few measured hydraulic property 

values available in the model area. One aquifer test north of 

Springfield in the Ozark aquifer calculated the mean horizontal 
Summary and Conclusions 103

hydraulic conductivity to be 2.11 feet per day and the storage 

coefficient to be 1.6x10-4. Horizontal hydraulic conductivity 

values at selected wells were computed from specific capacity 

data and ranged from 0.20 to 8.73 feet per day in the Ozark 

aquifer. Hydraulic properties were estimated from these 

data, from values used in other groundwater models, and 

published values for aquifer materials. Estimated values 

were adjusted throughout the calibration process to minimize 

the difference between simulated head and observed 

water levels. In the calibrated model, horizontal hydraulic 

conductivity for the Springfield Plateau aquifer ranged from 

2.20 to 5.00 feet per day, vertical hydraulic conductivity 

ranged from 0.050 to 0.167 feet per day, specific storage was 

1.00x10-5 per foot, and specific yield was 0.003. The Ozark 

confining unit horizontal hydraulic conductivity ranged 

from 1.00x10-6 to 7.50x10-5 feet per day, vertical hydraulic 

conductivity ranged from 2.00x10-7 to 1.50x10-5 feet per day, 

specific storage was 5.00x10-6 per foot, specific yield was 

0.100. The Ozark aquifer horizontal hydraulic conductivity 

ranged from 0.25 to 3.00 feet per day, vertical hydraulic 

conductivity ranged from 0.030 to 0.300 feet per day, specific 

storage ranged from 1.00x10-8 to 5.00x10-4 per foot, and 

specific yield was 0.003.

Water-level observation data for the Springfield 

Plateau aquifer and the Ozark aquifer were compiled 

from multiple sources. The steady-state part of the model 

was calibrated to water levels obtained from the Missouri 

Department of Natural Resources well log database 

supplemented with observation points interpolated from 

published predevelopment potentiometric surface maps of the 

Springfield Plateau and Ozark aquifers. The transient part of 

the model was primarily calibrated to water levels collected in 

2006–07 by the USGS. Additional water-level measurements 

collected by the USGS in 1987, 1989, 1993, and 1996 also 

were used. Water-level data obtained from the Missouri 

Department of Natural Resources certified well database 

and the Missouri Department of Natural Resources well-log 

database also were used as water-level observations. A total 

of 2,076 water-level observations were used for calibration 

of the transient part of the model. Base-flow observations 

were estimated using the 7-day annual low-flow discharge 

values for the 2-year recurrence interval computed at USGS 

gage locations and estimated at ungaged sites. Spring-flow 

observations were obtained from various sources, including 

the Missouri Department of Natural Resources database, the 

USGS database, and published values.

The model was most sensitive to recharge and to 

horizontal hydraulic conductivity and specific storage in 

specific zones in the Ozark aquifer. The model was least 

sensitive to the specific yield in specific zones in the Ozark 

aquifer and specific storage in specific zones in the Springfield 

Plateau aquifer. The model was most sensitive to the same 

10 model parameters during both the calibration period, 

1987 to 2006, and the prediction period, 2007 to 2030, 

although the order was somewhat different.

Population and the associated groundwater use were 

estimated for 12 communities and the unincorporated area 

of Greene County based on past growth. Each was analyzed 

individually, and a low and high rate of growth, relative to 

the 2006 population, was computed for each community or 

group. Low growth rates ranged from 0.215 percent per year 

in Springfield to 6.997 percent per year in Rogersville. Total 

growth from 2006 to 2030 at the low growth rate ranged from 

5.2 percent in Springfield to 167.9 percent in Rogersville. 

High growth rates ranged from 0.236 percent per year in 

Springfield to 7.345 percent per year in Rogersville. Total 

growth from 2006 to 2030 at the high growth rate ranged from 

5.7 percent in Springfield to 176.3 percent in Rogersville. 

Seven hypothetical scenarios provided to the USGS by 

the Greene County Resource Management Department were 

simulated from 2007 to 2030. The first hypothetical scenario 

was to run the simulation using the 2006 pumping rates. The 

potentiometric surface from 2006 to 2030 showed continuous 

decline in the Springfield area, with a maximum decrease 

of approximately 62 feet. Decline in the Nixa, Ozark, and 

Republic area ranged from about 15 to 45 feet. Two population 

growth rates were used to estimate groundwater demand in the 

future scenarios. Hypothetical scenarios 2 and 3 examined the 

effects that the low population growth rate combined with a 

4-year drought (precipitation = 25.21 inches per year) either at 

the beginning or the end of the simulation could have on the 

head distribution in the Ozark aquifer. For both scenarios, the 

lowest 2030 simulated head occurred in Springfield and had 

a maximum change from the 2006 levels of approximately 

203 feet. There was little difference in the potentiometric 

surface relative to the timing of the drought period except for 

where the Ozark aquifer is exposed. For scenarios 2 and 3, 

maximum groundwater declines at Nixa, Ozark, and Republic, 

relative to the 2006 levels, were greater than 100 feet. 

Hypothetical scenarios 4 and 5 examined the effects that the 

high population growth rate combined with a 4-year drought 

at the beginning or the end of the simulation could have on 

the potentiometric surface in the Ozark aquifer. Results of 

scenarios 4 and 5 were similar to the scenario 2 and 3 results. 

The maximum change occurred in the same vicinity and 

was approximately 207 ft lower than the 2006 levels. 

Potentiometric-surface declines for the high population growth 

scenarios 4 and 5 were similar to the low population growth 

scenarios 2 and 3 in the communities of Nixa, Ozark, and 

Republic. Hypothetical scenarios 6 and 7 examined the effects 

of the low and high growth rates in combination with the 

installation and operation of two new 900 gallon per minute 

(2010 rate) industrial wells in the model area. Little difference 

was noted in the potentiometric surface between the low and 

high growth scenarios 6 and 7. Both had substantial drawdown 

at the new wells (greater than 640 ft compared to the 

2006 levels), but the difference between the two was less than 

7 feet. The difference between all the low and high population 

growth scenarios was small. The drawdown at the new wells 

diminished relatively quickly with increased distance from the 
104 Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030

well. Simulated head in Nixa, Ozark, and Republic was nearly 

the same for scenarios 2 through 7; the potentiometric surface 

in 2030 near these towns could decline 100 feet or more from 

the 2006 levels. Because model layers 2 and 3 were simulated 

as confined, drawdown in the wells in the area of the Ozark 

aquifer that is unconfined or becomes unconfined during the 

simulation period will likely be under predicted. 

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Richards, J.M.,—Groundwater-Flow Model and Effects of Projected Groundwater Use, Greene County, Missouri—1907-2030—SIR 2010-5227