Potentiometric Surface

The potentiometric-surface map of the Ozark aquifer is a two-dimensional depiction of a 

three-dimensional view of the surface. The groundwater altitudes used in the map construction 

represent altitudes at which the water level would have stood in a tightly cased well; the map 

should not be used to determine the absolute water-level altitude or depth to water at any given 

location because of the variable geology and hydrologic properties of the study area and because 

of the changing nature of water levels through time. The potentiometric surface indicates 

the general direction of groundwater flow; under isotropic conditions, groundwater flow is 

perpendicular to the lines of equal hydraulic head and in the direction of hydrologic gradient. 

The Ozark aquifer is unconfined across more than 50 percent of the potentiometric 

map area, and groundwater flow is predominantly driven by topography. A radial flow 

pattern moving north from the central Ozarks towards the Missouri River, west towards the 

freshwater-saline water transition zone, east towards the Mississippi River and Mississippi 

River Valley alluvial aquifer, and south towards the Arkansas River is a key characteristic of 

the flow system (fig. 3). A well in Lawrence County, Mo., with a maximum groundwater-level 

altitude of 1,366 ft, located in a topographic high, and a well in Randolph County, Ark., with a 

minimum groundwater-level altitude of 178 ft, located in a topographic low, are examples of 

how groundwater flow in the Ozark aquifer is driven by hydraulic head. Topographic control of 

flow and the connection between groundwater and surface water are illustrated where contours 

crossing streams form a “V” pointing towards higher altitudes where water from the aquifer is 

discharging into the streams. Streams, incised in lower altitude valleys, across the study area 

have V-shaped contours that point towards the lower altitudes, indicating reaches where streams 

act as discharge points for the Ozark aquifer. This pattern of V-shaped contours is well illustrated 

in lower water-level altitude areas along streams such as the Big Piney River, Current River, 

Eleven Point River, Gasconade River, Jacks Fork River, and Roubidoux Creek in the northcentral part of the study area, west of the Saint Francois Mountains (fig. 3). 

Within the limitations of the regional-scale dataset, the groundwater-flow directions 

show good agreement with previously constructed, local- and regional-scale Ozark aquifer 

potentiometric maps (Imes and Emmett, 1994; Richards and Mugel, 2008; Schrader, 2015). 

Differences in these potentiometric surfaces may be ascribed to the size of the mapped area 

(regional or local scales), number of wells that were measured (data density), and timing 

(such as the season, year, decade) of measurements. On the regional potentiometric surface in 

the southwestern part of the study area in Jasper and McDonald Counties, Mo., groundwater 

declines are evident when compared to the predevelopment potentiometric-surface map by 

Imes and Emmett (1994). Groundwater-level altitudes in Kansas range from a low of 596 

ft to a high of 805 ft in Cherokee County, Kans., and from a low of 660 ft to a high of 702 

ft in the southeastern corner of Crawford County, Kans. While the southeastern corner of 

Crawford County, Kans., does show a slight decline (42 ft difference between the low and high 

groundwater-level altitudes), smaller scale cones of depression are not evident because of the 

large scale of the regional potentiometric surface. In Oklahoma (Gillip and others, 2008) and 

in Springfield, Greene County, Mo. (Richards and Mugel, 2008), two cones of depression on 

a local scale are displayed to compare with the current regional potentiometric surface and to 

highlight the historical importance of groundwater-level declines in these areas. Past water-level 

measurement data and resulting previously constructed, local-scale potentiometric maps detail 

water-level declines and the formation of cones of depression in southeastern Kansas (Cherokee 

and Crawford Counties), Missouri (Barry, Barton, Cedar, Dade, Greene, Jasper, Lawrence, 

McDonald, and Newton Counties), and northwestern Oklahoma (Craig and Ottawa Counties) 

(Czarnecki and others, 2009; Czarnecki and others, 2014; Gillip and others, 2008; Richards, 

2010; Richards and Mugel, 2008). 

The population increase, growing demand for water, and water-quality issues in 

southwestern Missouri are causing communities such as in Jasper and McDonald Counties, Mo., 

to assess the Ozark aquifer and its ability to sustain long-term population growth (Czarnecki 

and others, 2009; Gillip and others, 2008; Wittman and others, 2003). Low groundwater-level 

altitudes of 574 ft measured in an observation well northeast of Carthage, Jasper County, Mo., 

and 589 ft in a well in Webb City, Jasper County, Mo., indicate local groundwater-level declines 

(Wittman and others, 2003). Conversely, a well in Oronogo, Mo., located north of Webb City, 

had a groundwater-level altitude of 895 ft, and an observation well southwest of Carthage, Mo., 

had a groundwater-level altitude of 953 ft; these communities reported no groundwater declines 

according to Wittman and others (2003). The contrast in relatively high and low groundwater 

levels over short distances emphasizes the local influence of pumping from the Ozark aquifer. 

In areas where the Ozark aquifer is confined, groundwater levels respond differently to water 

withdrawals compared to groundwater levels in unconfined areas of the aquifer. Water-level 

declines induced by a given amount of pumping are greater in confined areas as compared 

to unconfined areas because water is yielded primarily by the compressibility of the rock 

matrix rather than by dewatering of the saturated porosity. Additionally, for wells where water 

withdrawals are high and the aquifer has low transmissivity and storage, longer recovery periods 

and more expansive cones of depression may be expected. 

South of Jasper County, Mo., groundwater declines can be seen in the town of Noel, 

McDonald County, Mo., in an observation well with a groundwater-level altitude of 349 ft that 

lies in a distinct cone of depression. When the well for the town of Noel was drilled in 1936, it 

was a flowing artesian well, but by 1962, water levels had declined to 48 ft below land surface 

(Missouri Department of Natural Resources, 2015). The groundwater-level measurement made 

for this study in late 2014 to early 2015 indicates that water levels in Noel, Mo., have declined 

116 ft since 2006. The MODNR reported that the potentiometric surface has declined more than 

400 ft since 1936 when the well was drilled. In contrast, the water-level altitude measured in 

a well in Benton County, Ark., approximately 20 miles southwest of Noel, Mo., is 1,011 ft, a 

difference in the water-level altitude of 662 ft. While the potentiometric surface does indicate 

considerable groundwater declines in northwestern Arkansas as a result of the cone of depression 

or in comparison with the Imes and Emmet (1994) map, declines have been noted over time 

in areas of development and population growth for individual wells in Benton, Carroll, and 

Washington Counties, Ark. (Czarnecki and others, 2014; Kresse and others, 2014); however, 

groundwater use from the Ozark aquifer in northwestern Arkansas has decreased, and surface 

water for public-supply use has increased as more communities convert to surface-water use 

because of issues arising over groundwater quantity and quality (Kresse and others, 2014). 

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Figure 3 Regional potentiometric surface for the Ozark aquifer from November 2014 through January 2015.

Acknowledgments

The author would like to thank the USGS 

Groundwater Resources Program for providing funding to 

conduct this study. The author would like to also thank all 

public and private landowners who provided information 

and access to their water wells for groundwater-level 

measurements. Thanks also are extended to Joseph 

Richards with the USGS for providing expertise, 

suggestions, and information and to David “Charlie” 

Smith, Jarrett Ellis, Gregory Johnson, and Joshua 

Blackstock with the USGS for measuring groundwater 

levels in Missouri and Arkansas. Cristi Hansen with the 

USGS and Caleb Fabrycky with the Kansas Department 

of Agriculture–Division of Water Resources provided 

groundwater levels at real-time observation wells in 

Kansas. 

The regional Ozark aquifer potentiometric-surface map shows the altitude at which the water level 

would have risen in tightly cased wells and represents conditions during the period from November 

2014 through January 2015 (fig. 3). Water levels were measured during this period to ensure that wells 

had adequate time to recover from previous summer pumping and prior to the start of the 2015 summer 

pumping season. Groundwater-level data from 178 wells cased completely in and open to the Ozark 

aquifer are available from the USGS National Water Information System (NWIS; data available at http://

waterdata.usgs.gov/nwis). Groundwater wells were determined to be completed within Ozark aquifer 

geologic units (fig. 2) by evaluating lithology from geophysical logs, groundwater driller logs, total depth, 

casing depth, publications, and available historical groundwater-level data. Groundwater-level data were 

collected for Arkansas, Kansas, and Missouri; however, groundwater-level data were not collected for 

Oklahoma because of the local practice of completing wells in both the Springfield Plateau and Ozark 

aquifers and a lack of completion data to indicate wells that were completed solely in the Ozark aquifer. 

Streams and springs in the study area represent the intersection of the groundwater table with land 

surface; these features were used in the construction of the potentiometric-surface map. In Arkansas and 

Missouri, where the Ozark aquifer crops out, altitudes of select gaining stream reaches, compiled from 

previous reports on gaining and losing streams (data available at http://dx.doi.org/10.5066/F7W9577Q) 

and select springs (data available at ftp://msdis.missouri.edu/pub/Inland_Water_Resources/MO_2010_

Springs_shp.zip), were calculated from 10-meter digital elevation data (Knierim and others, 2015; 

Missouri Department of Natural Resources and others, 2010). 

Representative and uniform data distribution is important when developing a potentiometric-surface 

map; therefore, a spatial analysis of sites in a geographic information system by using data from the 

USGS NWIS, Missouri Spatial Data Information Service, and Missouri Department of Natural Resources 

(MODNR) was conducted to identify areas with sparse data. Kansas groundwater-level measurements 

were collected from observation wells by the Kansas Department of Agriculture–Division of Water 

Resources personnel. 

Groundwater levels were measured by using a calibrated, graduated steel tape and an electric 

water-level indicator or by making an air-pressure gage measurement. Calibrated tapes are accurate to 

within 0.01 foot (ft), but the accuracy of air-pressure gage measurements ranges from 1 to 10 ft (Garber 

and Koopman, 1968; Gillip and others, 2008). Field-collected groundwater levels are subject to potential 

measurement errors including nonrepresentative water-level measurements possibly caused by recent or 

nearby pumping, inaccurate airline measurement or inaccurate airline length reported, and nonavailability 

and inaccuracy of well-construction information. Well-construction information was collected from well 

owners or from posted information at well sites. To reduce possible errors or data inconsistencies, all field 

sheets and water-level collection software data files were reviewed for accurate well location, altitudes, 

and construction information. Well driller logs, State and Federal agency well databases, and aerial 

photographs were used to check for accuracy and consistency. To verify field measurements, historical 

water-level data and recent well driller logs from each State, which include static groundwater-level 

measurements obtained during well installation, were reviewed and compared to groundwater levels 

measured for this study. Groundwater-level measurements were converted from depth below land surface, 

in feet, to groundwater-level altitude, in feet. Well altitudes, used to calculate groundwater-level altitudes, 

originally reported with respect to the National Geodetic Vertical Datum of 1929 (NGVD 29), were 

converted to the North American Vertical Datum of 1988 (NAVD 88), for consistency. 

After collecting and processing the data, a potentiometric surface was generated by using the 

interpolation method TopotoRaster in ArcMap. This tool is specifically designed for the creation of 

hydrologically correct digital elevation models while imposing constraints that ensure a connected 

drainage structure and a correct representation of the surface from the provided contour data (Esri, 2011). 

Once the raster surface was created, 100-ft contours were generated by using Contour (Spatial Analyst), 

which is a spatial analyst tool (available through ArcGIS Spatial Analyst Toolbox) that creates a linefeature class of contours (isolines) from the raster surface (Esri, 2008). Contours were manually adjusted 

based on topographical influence, a comparison with the regional map of Imes and Emmett (1994), and 

data point water-level altitudes to more accurately represent the potentiometric surface.

Methods

Introduction

The Ozark aquifer, within the Ozark Plateaus aquifer system (herein referred to as the “Ozark system”), is the 

primary groundwater source in the Ozark Plateaus physiographic province (herein referred to as the “Ozark Plateaus”) 

of Arkansas, Kansas, Missouri, and Oklahoma (fig. 1) (Fenneman, 1938; Fenneman and Johnson, 1946). Groundwater 

from the Ozark system has historically been an important part of the water resource base, and groundwater availability 

is a concern in some areas; dependency on the Ozark aquifer as a water supply has caused evolving, localized issues. 

The construction of a regional potentiometric-surface map of the Ozark aquifer is needed to aid assessment of 

current and future groundwater use and availability. The regional potentiometric-surface mapping is part of the U.S. 

Geological Survey (USGS) Groundwater Resources Program initiative (http://water.usgs.gov/ogw/gwrp/activities/

regional.html) and the Ozark system groundwater availability project (http://ar.water.usgs.gov/ozarks), which seeks to 

quantify current groundwater resources, evaluate changes in these resources over time, and provide the information 

needed to simulate system response to future human-related and environmental stresses. 

The Ozark groundwater availability project objectives include assessing (1) growing demands for groundwater 

and associated declines in groundwater levels as agricultural, industrial, and public supply pumping increases to 

address needs (Dintelmann and others, 2006; Emmett and others, 1978a; Richards, 2010; Richards and Mugel, 

2008); (2) regional climate variability and pumping effects on groundwater and surface-water flow paths (Imes 

and Emmett, 1994; Macfarlane and Hathaway, 1987); (3) effects of a gradual shift to a greater surface-water 

dependence in some areas (Kresse and others, 2014); and (4) shale-gas production requiring groundwater and 

surface water for hydraulic fracturing (Kresse and others, 2012; U.S. Environmental Protection Agency, 2010). Data 

compiled and used to construct the regional Ozark aquifer potentiometric surface will aid in the assessment of those 

objectives. 

The purpose of this report is to document a regional potentiometric surface of the Ozark aquifer representing 

synoptic conditions from November 2014 through January 2015. The potentiometric surface can be used to evaluate 

groundwater-level changes, provide calibration and simulation targets for the Ozark system regional groundwater 

flow model, and provide complementary data to the Ozark system groundwater availability project. A regional 

potentiometric map of the Ozark aquifer has not been completed since the detailed hydrogeologic studies of the 

Ozark Plateaus aquifer system investigated by Imes (1990) and Imes and Emmett (1994, figs. 28 and 40), as part of 

the 1981 Central Midwest Regional Aquifer-System Analysis (Jorgensen and Signor, 1981) of the 1978–96 USGS 

Regional Aquifer-System Analysis Program, approximated a predevelopment surface (Gillip and others, 2008). The 

regional potentiometric surface for this report shows large-scale groundwater-level characteristics, but the regional 

potentiometric surface does not show smaller, local-scale detail, such as localized cones of depression that may 

be indicative of evolving local issues. The regional map does not invalidate previous local-scale observations and 

efforts, as the scope of this regional study did not include the extensive measurements required to delineate localscale depressions. The potentiometric surface, however, shows regionally important details such as water-level 

patterns highlighting the intimate connection between surface water and groundwater across large areas and regional 

groundwater-flow directions. For information on local-scale conditions, the reader is referred to studies that include 

finer scale water-level measurement data for the study area (Aley, 1988; Czarnecki and others, 2009, 2014; Dintelmann 

and others, 2006; Emmett and others, 1978b; Gillip and others, 2008; Imes, 1989a, 1989b, 1990, 1991; Imes and 

Emmett, 1994; Imes and Kleeschulte, 1995; Imes and others, 2007; Juracek and Hansen, 1996; Kleeschulte, 2001, 

2006; Macfarlane and Hathaway, 1987; Mugel and Imes, 2003; Mugel and others, 2009; Pugh, 1998, 2008; Richards, 

2010; Richards and Mugel, 2008; Schrader, 2001, 2005, 2015; Steinkamp, 1987; Vandike, 1992).

Hydrogeologic units and geology of the study area have been studied extensively (Adamski and 

others, 1995; Banner and others, 1989; Ethington and others, 2012; Harrison and McDowell, 2003; 

Harrison and others, 2002; Hudson, 2000; Hudson and others, 2006; Hudson and Turner, 2007, 2009, 

2014; Imes, 1989b, 1989c, 1990; Imes and Emmett, 1994; Jorgenson and others, 1993; Kleeschulte and 

Seeger, 2003; Kresse and others, 2014; McDowell and others, 2000; Miller and Appel, 1997; Mugel and 

Imes, 2003; Orndorff, 2003; Orndorff and Harrison, 2001; Smith and Imes, 1991; Turner and Hudson, 

2010; Weary, 2015; Weary and McDowell, 2006; Weary and others, 2013, 2015; Weary and Schindler, 

2004; Weems, 2002; Whitfield and others, 1994). In this report, hydrogeologic characteristics are 

briefly discussed, and geologic units of the Ozark aquifer follow naming conventions used in Missouri. 

Figure 2 lists the stratigraphically equivalent geologic units names for Arkansas, Kansas, and Oklahoma, 

and the units are divided into the upper, middle, and lower Ozark aquifer (Imes and Emmett, 1994). 

Figure 1 shows aquifers and confining units, which compose the physiographic province and sections 

in the study area. The reader should note that aquifer systems in figure 1 refer to a “heterogeneous body 

of intercalated permeable and poorly permeable material that functions regionally as a water-yielding 

hydraulic unit; it comprises two or more permeable beds (aquifers) separated at least locally by confining 

units that impede groundwater movement but do not greatly affect the regional hydraulic continuity 

of the system” (Poland and others, 1972). Aquifers and confining units are named for province and its 

subdivisions; nomenclature associated with the correlation of hydrogeologic formations will have the 

designation of aquifer or aquifer system implied for any formation or group of formations for this report. 

The study area is bounded to the north by the Missouri River, to the south by the Arkansas River 

and Boston Mountains of the Ozark Plateaus, to the west by a freshwater-saline water transition zone 

along the Central Lowland-Ozark Plateaus province boundaries, and to the east by the Mississippi River 

and Mississippi River Valley alluvial aquifer of the Coastal Plain province (fig. 1). The Ozark system is 

primarily located in the physiographic province, Ozark Plateaus, which comprises three physiographic 

sections: Salem Plateau, Springfield Plateau, and the Boston Mountains (fig. 1). The Ozark system is 

divided into five hydrogeologic units (youngest to oldest) (fig. 2): Springfield Plateau aquifer, Ozark 

confining unit, Ozark aquifer, St. Francois confining unit, and St. Francois aquifer (Imes and Emmett, 

1994). The Ozark system is geologically complex and includes Cambrian- to Mississippian-age strata. 

The Ozark system aquifers, comprising carbonate karst and granular-media strata, are bound by confining 

layers of variable extent and competency. The Ozark system aquifers have experienced fracturing, 

faulting, and extensive dissolution of soluble rocks that have modified primary rock properties and 

the ability to convey and store water. For the carbonate units, fracturing and faulting provided initial 

pathways for dissolution and karst development, resulting in intimate connection of groundwater with 

surface water across large areas. 

The Ozark aquifer lies between the Springfield Plateau and St. Francois aquifers (fig. 2) in the 

Ozark system and is the largest and most important aquifer of the region; many public and private 

supplies depend entirely upon the Ozark aquifer because of the productivity and widespread availability 

of the aquifer (Vandike, 1992). The Ozark aquifer has been separated into upper, middle, and lower Ozark 

aquifer hydrogeologic units (fig. 2) as part of the USGS Groundwater Resources Program initiative, based 

upon previously compiled data on the geologic characteristics and hydrologic properties of the rocks and 

modified from Imes and Emmett (1994); however, groundwater-level measurements collected for this 

map did not distinguish between upper, middle, and lower units because of completion practices typical 

of the region and lack of sufficiently detailed completion information for many wells. The upper Ozark 

aquifer is carbonate dominated, comprising Devonian-, Silurian-, and Ordovician-age rocks. The middle 

Ozark aquifer comprises the Cotter Dolomite and Jefferson City Dolomite of Ordovician age. The lower 

Ozark aquifer includes Ordovician-age (Roubidoux Formation, Gasconade Dolomite, and Van Buren 

Formation-Gunter Sandstone Member) and Cambrian-age (Eminence Dolomite and Potosi Dolomite) 

hydrogeologic units. 

The Ozark aquifer is generally under unconfined conditions where it crops out across the Salem 

Plateau section (Miller and Appel, 1997); in the Saint Francois Mountains (fig. 1), the aquifer has been 

removed by erosion. The Ozark aquifer is generally under confined conditions across the Springfield 

Plateau (fig. 1), where the aquifer is overlain by the Ozark confining unit, which in turn is overlain by the 

Springfield Plateau aquifer. The middle Ozark aquifer does have limited exposures along river valleys 

in McDonald, Lawrence, Dade, and St. Clair Counties in Missouri, as well as in Madison and Benton 

Counties in Arkansas. Recharge to the Ozark aquifer, where unconfined, is primarily by infiltration of 

rainfall, and where confined, recharge originates from downgradient flow from outcrop areas of the Ozark 

aquifer and leakage from the Springfield Plateau aquifer (Kresse and others, 2014). 

To the west of the Salem-Springfield Plateaus and south of the Boston Mountains lies the Western 

Interior Plains confining system within the Central Lowland-Ozark Plateaus provinces. The Western 

Interior Plains confining system overlies the Ozark system and the Western Interior Plains aquifer system 

and consists of a thick sequence of Pennsylvanian sedimentary rocks of low permeability. Groundwater 

discharged from the Western Interior Plains aquifer system is slightly saline (around 1,000 milligrams 

per liter or more dissolved solids) because of leakage from saline formations, particularly from the 

Permian strata of the Western Interior Plains confining unit (Banner and others, 1989; Imes, 1985; Imes 

and Emmett, 1994). The Western Interior Plains aquifer system merges into the freshwater-saline water 

transition zone where flow gradients induce a vertical component of flow resulting in discharge into 

streams as base flow and into alluvial deposits in stream valleys (Miller and Appel, 1997). 

Recharge in the higher altitude water-level areas (indicated by blue shading on the potentiometricsurface map, fig. 3), where the Ozark aquifer is exposed is generally by direct recharge from precipitation. 

Short, shallow flow paths are important in outcrop areas of the Ozark aquifer where precipitation 

quickly infiltrates into the subsurface and groundwater moves quickly to deeply incised streams in these 

high-relief, upland areas (Adamski and others, 1995; Kresse and others, 2014). Because of the rapid 

recharge and drainage occurring in these unconfined, upland areas of the Ozark aquifer, highly variable 

groundwater-gradient reversals are common (Aley, 1988; Kresse and others, 2014); hence, regional flow 

is controlled by regional topographic highs, and shallower, shorter local flow systems controlled by local 

topography are superimposed on this larger framework. Water discharged from the Ozark aquifer moves 

into the streams, springs, and karst features, such as dissolution-enlarged fractures, bedding planes, and 

caves, located along flow paths. 

Hydrogeologic Setting

Figure 2. Stratigraphic units and regional geohydrologic units (modified from Imes and Emmett, 1994). 

[Blue lines mark boundaries between hydrogeologic units. Shading represents divisions between the upper (green), middle (red), and lower (blue), Ozark aquifer. Modified from Imes and Emmett, 1994 (table 1)]

Era System Southeastern Missouri Southwestern Missouri Southeastern Kansas Northeastern Oklahoma Northern Arkansas

Aquifers and confining units

described in the report

Hydrogeologic

unit

Hydrogeologic

system

PENNSY

LVANIAN

Kansas City Group Kansas City Group

W

ESTERN INTE

RIO

R PL

AINS C

O

NFININ

G SYSTE

M2

Pleasanton Formation1 Pleasanton Formation Pleasanton Group

Marmaton Group1 Marmaton Group Marmaton Group Marmaton Group

Cherokee Shale1 Cherokee Shale Cherokee Group Cabiniss Group McAlester Formation

Krebs Group Hartshorne Sandstone

Atoka Formation Atoka Formation

Bloyd Shale Bloyd Shale

Hale Formation Hale Formation

PALE

O

ZOI

C

MISSISSIPPIAN

Vienna Limestone1 Pitkin Limestone Pitkin Limestone

Tar Springs Sandstone1

Glen Dean Limestone1

Hardinsburg Sandstone1

Golconda Formation1

Cypress Formation1

Paint Creek Formation1 Fayetteville Shale Fayetteville Shale Fayetteville Shale

Yankeetown Sandstone1 Batesville Sandstone Batesville Sandstone Batesville Sandstone

Renault Formation1 Hindsville Limestone Hindsville Limestone

Aux Vases Sandstone1 Carterville Formation

Ste. Genevieve

Limestone3

St. Louis Limestone3 St. Louis Limestone St. Louis Limestone Moorefield Formation Moorefield Formation

Salem Limestone3 Salem Limestone Salem Limestone

SPRIN

GFIEL

D PL

ATE

A

U

A

Q

UIFE

R

O

ZAR

K PL

ATE

AUS 

A

Q

UIFE

R SYSTE

M5

Warsaw Limestone3 Warsaw Limestone Warsaw Limestone

Keokuk Limestone3 Keokuk Limestone Keokuk Limestone Keokuk Limestone

Burlington Limestone3 Burlington Limestone Burlington Limestone

Elsey Formation

Reeds Spring Formation

Fern Glen Limestone3 Pierson Formation Fern Glen Limestone Boone Formation Boone Formation

Reeds Spring Member Reeds Spring Member

St. Joe Limestone

Member

St. Joe Limestone 

Member

Chouteau Limestone

Hannibal Shale

Bachelor Formation4

Northview Shale

Sedalia Limestone

Compton Limestone

Chouteau Limestone Northview Equivalent

Compton Equivalent

O

ZAR

K

C

O

NFININ

G

UNIT

D

E

V

O

NIAN

Bushberg Sandstone

Glen Park Limestone Woodford Chert

Chattanooga Shale Chattanooga Shale Chattanooga Shale Chattanooga Shale Chattanooga Shale

St. Laurent Limestone

Grand Tower Limestone

Clear Creek Chert

Little Saline Limestone

Bailey Limestone

Callaway Formation

Fortune Formation4

Salisaw Formation

Frisco Limestone

Clifty Limestone

Penters Chert

UPP

E

R

O

ZAR

K

A

Q

UIFE

R

SILURIAN

Bainbridge Limestone

Sexton Creek Limestone4 St. Clair Limestone

Lafferty Limestone

St. Clair Limestone

Brassfield Limestone

ORD

O

VICIAN

Girardeau Limestone

Orchard Creek Shale

Thebes Sandstone

Maquoketa Shale

Kimmswick Limestone

Plattin Limestone

Joachim Dolomite

St. Peter Sandstone

Everton Formation

Smithville Formation

Powell Dolomite

Sylvan Shale

Fernvale Limestone

Viola Limestone

Fite Limestone

Tyner Formation

Burgen Sandstone

Smithville Equivalent

Powell Dolomite

Cason Shale

Fernvale Limestone

Kimmswick Limestone

Plattin Limestone

Joachim Dolomite

St. Peter Sandstone

Everton Formation

Smithville Formation

Powell Dolomite

Cape Limestone4

Kimmswick Limestone

Decorah Formation

Plattin Limestone

Rock Levee Formation4

Joachim Dolomite

Dutchtown Formation4

St. Peter Sandstone

Everton Formation

Smithville Formation

Powell Dolomite

Cotter Dolomite

Jefferson City Dolomite

Cotter Dolomite

Jefferson City Dolomite

Cotter Dolomite

Jefferson City Dolomite

Cotter Dolomite

Jefferson City Dolomite

Cotter Dolomite

Jefferson City Dolomite MIDDLE

Roubidoux Formation

Gasconade Dolomite

Van Buren Formation

Gunter Sandstone

Member

Roubidoux Formation

Gasconade Dolomite

Gunter Sandstone

Member

Roubidoux Formation

Gasconade Dolomite

Van Buren Formation

Gunter Sandstone

Member

Roubidoux Formation

Gasconade Dolomite

Van Buren Formation

Gunter Sandstone

Member

Roubidoux Formation

Gasconade Dolomite

Van Buren Formation

Gunter Sandstone

Member L

O

W

E

R

CA

M

B

RIAN

Eminence Dolomite

Potosi Dolomite

Eminence Dolomite

Potosi Dolomite

Eminence Dolomite

Potosi Dolomite

Eminence Dolomite

Potosi Dolomite

Eminence Dolomite

Potosi Dolomite

Doe Run Dolomite

Derby Dolomite

Davis Formation

Doe Run Dolomite

Derby Dolomite

Davis Formation

Doe Run Dolomite

Derby Dolomite

Davis Formation

Doe Run Dolomite

Derby Dolomite

Davis Formation

Doe Run Dolomite

Derby Dolomite

Davis Formation

ST. FRANCOIS

CONFINING

UNIT

Bonneterre Formation6 Bonneterre Dolomite Bonneterre Dolomite6 Bonneterre Equivalent Bonneterre Dolomite ST. FRANCOIS

AQUIFER

Reagan Sandstone Reagan Sandstone Reagan Sandstone Reagan Sandstone Reagan Sandstone

Lamotte Sandstone Lamotte Sandstone Lamotte Sandstone Lamotte Sandstone Lamotte Sandstone

PRECAMBRIAN IGNEOUS AND METAMORPHIC ROCKS

BASEMENT

CONFINING

UNIT

1Geologic unit in southeastern Missouri that is stratigraphically equivalent to geologic units in the Western Interior Plains confining system but not part of the confining system. 

2The Western Interior Plains confining system also includes younger sediments west of the study area. 3Geologic unit in southeastern Missouri that is stratigraphically equivalent to geologic units in the Springfield Plateau aquifer but not part of the aquifer. 4Unit follows usage of the Missouri Division of Geology and Land Survey. 5The Western Interior Plains aquifer system deeply buried in the western part of the study area included, where permeable carbonate rocks in the subsurface are equivalents of the aquifers of the Ozark Plateaus aquifer

system (Miller and Appel, 1997). 

,

6Unit follows usage of the National Geologic Map Database.

Figure 1. Study area map showing surficial extent of aquifers and confining units of the Ozark Plateaus aquifer system, which compose the physiographic 

province and regions.

Base from U.S. Geological Survey digital data, 1:24,000

Alber Equal-Area Conic USGS projection

Standard parallels 29.5 and 45.5

Central meridian -96.0 

Hydrogeologic data modified from Haley and others, 1993;

Stoeser and others, 2007

Physiographic areas modified from Fenneman, 1938;

Adamski and others, 1995

Saint Francois

Mountains

Springfield

Plateau

Boston Mountains

Salem Plateau

CENTRAL LOWLAND

PROVINCE

COASTAL PLAIN

PROVINCE

OZARK PLATEAUS

PROVINCE

KANSAS

OKLAHOMA

 ARKANSAS

 MISSOURI

Study area boundary

PHYSIOGRAPHIC AREAS IN THE STUDY AREA

Arkansas River

Missouri Rive r

Mississippi River

Freshwater-saline water

transition zone

EXPLANATION

Coastal Plain aquifer system

 Mississippi River Valley alluvial aquifer

Central Lowland aquifer system

 Western Interior Plains confining system

Ozark Plateaus aquifer system

 Springfield Plateau aquifer

 Ozark confining unit

 Ozark aquifer

 St. Francois aquifer and confining unit

 Basement confining unit

Water bodies

Study area boundary—Boundary of extent

 of the Ozark Plateaus aquifer system,

 including subsurface

Note: Aquifer system names are derived from

 physiographic provinces

0 50 100 KILOMETERS

0 50 100 MILES

MISSOURI

ARKANSAS

KANSAS

OKLAHOMA

ILLINOIS

KENTUCKY

TENNESSEE

MISSISSIPPI

39°00'

37°00'

35°00'

39°00'

37°00'

35°00' 95°30' 93°30' 91°30' 89°30' 87°30'

85°30'

95°30' 93°30' 91°30' 89°30' 87°30' 85°30'

Springfield

Carthage

Webb

City

Noel

Oronogo

Joplin

90°

90°

92°

92°

94°

94°

38°

38°

36°

36°

Lake

of the

Ozarks

0 75 150 KILOMETERS

0 75 150 MILES

Missouri River

Arkansas River

MISSISSIPPI

RIVER

Big Piney River

Roubidoux

Creek

Gasconade River

Gasconade

R iver

Current River

Jacks Fork River

Eleven Point River

POLK

HICKORY

CAMDEN

LACLEDE

DALLAS

WEBSTER WRIGHT

TEXAS

SHANNON

CARTER

WAYNE

MADISON

IRON

REYNOLDS

DENT

PHELPS

PULASKI

MARIES

OSAGE

COLE

MILLER

MORGAN

BENTON

HENRY

JOHNSON

PETTIS COOPER

MONITEAU

DOUGLAS

TANEY

OZARK

HOWELL

OREGON

RIPLEY

CAPE

GIRARDEAU

PERRY

SAINTE GENEVIEVE SAINT FRANCOIS

BOLLINGER

CHRISTIAN

BOONE

MARION

DELAWARE

LE FLORE

VERNON

RANDOLPH

SHARP

IZARD

BAXTER

FULTON

INDEPENDENCE

STONE

FRANKLIN

CRAWFORD

JEFFERSON

WASHINGTON

SAINT LOUIS

GASCONADE

LABETTE

LAWRENCE

SEARCY STONE JACKSON

CHEROKEE

ADAIR

BUTLER

STODDARD

SCOTT

MCDONALD BARRY

NEWTON

LAWRENCE

GREENE

JASPER

BENTON

CARROLL

MADISON

WASHINGTON

IG

OTTAWA

AR

C

BARTON

CEDAR

DADE

ST. CLAIR

CRAWFORD

CHEROKEE

NEWTON

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1,026

1,049

1,106

1,062

1,279 1,366

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1,168

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500

600

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1,100

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1,200

1,300

1,400

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800

900

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1,000

600

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1,300

700

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1,200

1,000

1,000

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1,200

300

1,100

700

700

900

1,000

700

1,000

1,400

600

400

600

800

500

600

1,000

600

900

700

1,100

1,000

1,200

500

900

500

900

800

500

1,400

700

1,300

1,200

800

400

900

900

600

800

1,000

800

600

400

700

700

600

1,100

1,000

800

800

1,000

1,000

1,100

900

800

800

1,100

600

1,300

1,000

1,100

600

400

700

1,100

700

1,100

1,100

900

600

900

1,000

900

800

700

1,000

900

700

500

400

1,200

1,200

1,000

1,100

600 700

600

700

500

700

600

800

1,100

1,400

1,300

1,200

1,300

1,000

1,100

800

1,200

1,200

500

900

1,300

600

500

400

Base from U.S. Geological Survey (USGS) digital data, 1:900,000

Albers Equal Area Conic USGS projection

Standard parallels 29.5 and 45.5

Central meridian -96.0

OKLAHOMA

KANSAS

ARKANSAS

MISSOURI

ILLINOIS

Boundary of surficial extent of Ozark Plateaus 

 aquifer system

Boundary of extent of the Ozark Plateaus aquifer

 system, including subsurface

Potentiometric contour—Shows altitude

 at which water level would have stood

 in tightly cased well. Dashed where

 approximately located. Hachures

 indicate depression. Contour interval

 100 feet. Datum is NAVD 88

Approximate direction of groundwater flow

Gaining stream—Intersection of land-surface

 contour and stream within area where the

 Ozark aquifer is unconfined. Altitude 

 determined from a 10-meter digital elevation

 model (DEM) (modified from Knierim and 

 others, 2015)

Stream

City boundary 

Groundwater well completed in Ozark

 aquifer—Measurement made November

 2014 to January 2015. Value is water-level

 altitude above NAVD 88

Spring in the Ozark aquifer—Intersection of

 land-surface contour and spring within 

 area where the Ozark aquifer is unconfined. 

 Altitude determined from a 10-meter DEM 

 (modified from Missouri Department of 

 Natural Resources, 2010)

Freshwater-saline water transition zone

Groundwater-level altitude, in feet above 

 North American Vertical Datum of 1988

 (NAVD 88)—Areas of shaded relief for 

 each altitude interval indicate areas

 where the Ozark aquifer crops out

 No available data

 100 to 200

 200.1 to 300

 300.1 to 400

 400.1 to 500

 500.1 to 600

 600.1 to 700

 700.1 to 800

 800.1 to 900

 900.1 to 1,000

 1,000.1 to 1,100

 1,100.1 to 1,200

 1,200.1 to 1,300

 1,300.1 to 1,400

 1,400.1 to 1,500

Oklahoma cone of depression (2006)

 (modified from Gillip and others,

 2008)

500

"

1,100

EXPLANATION

U.S. Department of the Interior

U.S. Geological Survey

Groundwater Resources Program Scientific Investigations Map 3348

Regional Potentiometric Surface of the Ozark Aquifer in Arkansas, 

Kansas, Missouri, and Oklahoma, November 2014–January 2015

By

Anna M. Nottmeier

2015

Any use of trade, product, or firm names in this publication is for descriptive purposes only

and does not imply endorsement by the U.S. Government

For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, 

Denver, CO 80225, 1–888–ASK–USGS

Digital files available at http://dx.doi.org/10.3133/sim3348

Suggested citation: Nottmeier, A.M., 2015, Regional potentiometric surface of the Ozark aquifer 

in Arkansas, Kansas, Missouri, and Oklahoma, November 2014–January 2015: U.S. Geological 

Survey Scientific Investigations Map 3348, 1 sheet, http://dx.doi.org/10.3133/sim3348.

ISSN 2329-132X (online)

http://dx.doi.org/10.3133/sim3348