Prepared in cooperation with the

Arkansas Department of Health

HYDROGEOLOGIC CHARACTERISTICS OF FOUR 

PUBLIC DRINKING-WATER SUPPLY SPRINGS IN 

NORTHERN ARKANSAS

Water-Resources Investigations Report 03-4307

U.S. Department of the Interior

U.S. Geological Survey
Cover: Photograph of the outflow from the spring box of Hughes Spring near Zack, Arkansas. Photograph 

by Joel Galloway, U.S. Geological Survey.
HYDROGEOLOGIC CHARACTERISTICS OF FOUR 

PUBLIC DRINKING-WATER SUPPLY SPRINGS IN 

NORTHERN ARKANSAS

By Joel M. Galloway

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 03-4307

Prepared in cooperation with the

Arkansas Department of Health

Little Rock, Arkansas

2004
U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

For additional information Copies of this report can be

write to: purchased from:

District Chief U.S. Geological Survey

U.S. Geological Survey, WRD Branch of Information Services

401 Hardin Road Box 25286

Little Rock, Arkansas 72211 Denver Federal Center

Denver, Colorado 80225

The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey.
Contents III

CONTENTS

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

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

Purpose and Scope .................................................................................................................................... 3

Acknowledgments..................................................................................................................................... 5

Methods of Investigation.................................................................................................................................... 5

Hydrogeologic Assessment....................................................................................................................... 5

Discharge, Temperature, and Precipitation Monitoring............................................................................ 5

Water-Level Mapping................................................................................................................................ 6

Qualitative Ground-Water Tracing............................................................................................................ 7

Water Quality ............................................................................................................................................ 8

Spring Characterization....................................................................................................................................11

Hughes Spring.........................................................................................................................................11

Study Area Description..................................................................................................................11

Hydrogeology ................................................................................................................................11

Discharge, Temperature, and Precipitation ....................................................................................16

Water-Level Contours ....................................................................................................................17

Recharge Area Characterization ....................................................................................................20

Geochemistry .................................................................................................................................22

Stark Spring.............................................................................................................................................26

Study Area Description..................................................................................................................26

Hydrogeology ................................................................................................................................27

Discharge, Temperature, and Precipitation ....................................................................................27

Recharge Area Characterization ....................................................................................................27

Geochemistry .................................................................................................................................33

Evening Shade.........................................................................................................................................38

Study Area Description..................................................................................................................38

Hydrogeology ................................................................................................................................38

Discharge, Temperature, and Precipitation ....................................................................................41

Water-Level Contours ....................................................................................................................41

Recharge Area Characterization ....................................................................................................41

Geochemistry .................................................................................................................................41

Roaring Spring ........................................................................................................................................53

Study Area Description..................................................................................................................53

Hydrogeology ................................................................................................................................53

Discharge, Temperature, and Precipitation ....................................................................................57

Water-Level Contours ....................................................................................................................60

Recharge Area Characterization ....................................................................................................60

Geochemistry .................................................................................................................................62

Summary ..........................................................................................................................................................65

References........................................................................................................................................................67
IV Contents

ILLUSTRATIONS

Figure 1. Map showing location of springs and study areas............................................................................ 4

2. Photograph showing injection of eosine OJ dye into a swallow hole in the Hughes

Spring area ................................................................................................................................... 7

3. Stratigraphic column with descriptions of lithologic and geohydrologic properties of

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

within Arkansas ......................................................................................................................... 12

4. Map showing geology of the Hughes Spring study area ................................................................ 13

5. Map showing distribution of wells and springs in the Hughes Spring study area.......................... 14

6. Diagram showing conceptual model of ground-water flow to Hughes Spring .............................. 15

7. Graphs showing daily discharge, rainfall, and water temperature recorded at

Hughes Spring............................................................................................................................ 16

8. Graphs showing discharge and water temperature data from Hughes Spring for

four storm events........................................................................................................................ 17

 9. Map showing water-level contours of the Hughes Spring study area ........................................... 20

10. Map showing locations of dye injection and recovery sites with implied flow paths of

dyes and delineated recharge area for Hughes Spring............................................................... 21

11. Graph showing relation of ground-water samples from Hughes Spring and

other wells and springs in northern Arkansas and southern Missouri ....................................... 24

12. Graphs showing fecal indicator bacteria and nutrient concentrations for samples

collected from Hughes Spring ................................................................................................... 25

13. Graph showing relation of deuterium and oxygen-18 isotope ratios in ground-water

samples from Hughes Spring and other wells and springs in northern

Arkansas and southern Missouri................................................................................................ 26

14. Map showing geology of the Stark Spring study area.................................................................. 28

15. Diagram showing conceptual model of ground-water flow to Stark Spring ................................ 29

16. Graphs showing daily discharge, rainfall, and water temperature recorded at

Stark Spring. .............................................................................................................................. 30

17. Graphs showing discharge and water temperature data from Stark Spring for three

storm events ............................................................................................................................... 31

18. Graph showing runoff discharge for selected storms from Stark Spring ..................................... 31

19. Map showing locations of dye injection and recovery sites with implied flow path and

the estimated local recharge area for Stark Spring .................................................................... 32

20. Graph showing the relation of ground-water samples from Stark Spring and other

wells and springs in northern Arkansas and southern Missouri ................................................ 34

21. Graphs showing fecal indicator bacteria and nutrient concentrations for samples collected

at Stark Spring ........................................................................................................................... 37

22. Graph showing relation of deuterium and oxygen-18 isotope ratios in groundwater samples from Stark Spring and other wells and springs in northern Arkansas

and southern Missouri................................................................................................................ 37

23. Map showing geology of the Evening Shade Spring study area .................................................. 39

24. Map showing distribution of wells and springs in the Evening Shade Spring study area............ 40

25. Diagram showing conceptual model of ground-water flow to Evening Shade Spring ................ 42

26. Graphs showing daily discharge, rainfall, and water temperature recorded at

Evening Shade Spring................................................................................................................ 43

27. Map showing water-level contours of the Evening Shade Spring study area............................... 48

28. Graph showing the relation of ground-water samples from Evening Shade Spring

and other wells and springs in northern Arkansas and southern Missouri ................................ 52

29. Graph showing relation of deuterium and oxygen-18 isotope ratios in groundwater samples from Evening Shade Spring and other wells and springs in northern

Arkansas and southern Missouri................................................................................................ 53

30. Map showing geology of the Roaring Spring study area ............................................................. 54

31. Map showing distribution of wells and springs in the Roaring Spring study area ....................... 57

32. Diagram showing conceptual model of ground-water flow to Roaring Spring............................ 58

33. Graphs showing daily discharge, rainfall, and water temperature recorded at

Roaring Spring........................................................................................................................... 59

34. Map showing water-level contours of the Roaring Spring study area.......................................... 60
Contents V

35. Graph showing relation of ground-water samples from Roaring Spring and

other wells and springs in northern Arkansas and southern Missouri ........................................64

36. Graph showing relation of deuterium and oxygen-18 isotope ratios in the groundwater sample from Roaring Spring and other wells and springs in northern Arkansas

and southern Missouri.................................................................................................................65

TABLES

Table 1. List of water-quality properties and constituents collected and analyzed at Hughes, Stark, Evening 

Shade, and Roaring Springs..........................................................................................................9

2. Tritium concentrations with relative ages........................................................................................11

3. Wells and springs inventoried in the Hughes Spring study area......................................................18

4. Results of ground-water tracer tests in the Hughes Spring study area ............................................22

5. Water-quality analyses from samples collected at Hughes Spring, 2001-2002...............................23

6. Storm events and calculated recharge areas for Stark Spring..........................................................33

7. Results of ground-water tracer tests in the Stark Spring study area ................................................35

8. Water-quality analyses from samples collected at Stark Spring, 2001-2002...................................36

9. Wells and springs inventoried in the Evening Shade Spring study area..........................................44

10. Water-quality analyses from samples collected at Evening Shade Spring, 2001-2002...................50

11. Water-quality analyses of samples collected from three wells and one spring in the

Evening Shade Spring study area on October 16 and 17, 2002..................................................51

12. Wells and springs inventoried in the Roaring Spring study area .....................................................55

13. Water-quality analyses from samples collected at Roaring Spring, 2001-2002 ..............................61

14. Water-quality analyses of samples collected from two wells and two springs in the

Roaring Spring study area on October 16 and 17, 2002.............................................................63

In this report, vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD of 

1929). Horizontal coordinate information is referenced to North American Datum of 1983 (NAD 83).

CONVERSION FACTORS, ABBREVIATIONS, AND VERTICAL DATUM

Multiply By To obtain

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

miles per day (mi/d) 1.609 kilometer per day (m/d)

mile (mi) 1.609 kilometer (km)

square mile (mi2) 2.590 square kilometer (km2)

cubic foot per second (ft3/s) 0.01093 cubic meter per second (m3/s)

degree Celsius (° C) 1.8 x ° C + 32 degree Fahrenheit
Abstract 1

HYDROGEOLOGIC CHARACTERISTICS OF FOUR PUBLIC 

DRINKING-WATER SUPPLY SPRINGS IN NORTHERN 

ARKANSAS

By Joel M. Galloway

ABSTRACT

In October 2000, a study was undertaken by 

the U.S. Geological Survey (USGS) in cooperation with the Arkansas Department of Health to 

determine the hydrogeologic characteristics, 

including the extent of the recharge areas, for 

Hughes Spring, Stark Spring, Evening Shade 

Spring, and Roaring Spring, which are used for 

public-water supply in northern Arkansas. Information pertaining to each spring can be used to 

enable development of effective management 

plans to protect these water resources and public 

health. 

An integrated approach to determine the 

ground-water characteristics and the extent of the 

local recharge areas of the four springs incorporated tools and methods of hydrology, structural 

geology, geomorphology, geophysics, and 

geochemistry. Analyses of discharge, temperature, 

and water quality were completed to describe 

ground-water flow characteristics, source-water 

characteristics, and connectivity of the groundwater system with surface runoff. Water-level contour maps were constructed to determine groundwater flow directions and ground-water tracer tests 

were conducted to determine the extent of the 

recharge areas and ground-water flow velocities. 

Hughes Spring supplies water for the city of 

Marshall, Arkansas, and the surrounding area. The 

mean annual discharge for Hughes Spring was 2.9 

and 5.2 cubic feet per second for water years 2001 

and 2002, respectively. Recharge to the spring 

occurs mainly from the Boone Formation (Springfield Plateau aquifer). Ground-water tracer tests 

indicate the recharge area for Hughes Spring generally coincides with the surface drainage area 

(15.8 square miles) and that Hughes Spring is connected directly to the surface flow in Brush Creek.

The geochemistry of Hughes Spring demonstrated variations with flow conditions and the 

influence of surface-runoff in the recharge area. 

Calcite saturation indices, total dissolved solids 

concentrations, and hardness demonstrate noticeable differences with flow conditions reflecting 

the reduced residence time and interaction of 

water with the source rock within the groundwater system at higher discharges for Hughes 

Spring. Concentrations of fecal indicator bacteria 

also demonstrated a substantial increase during 

high-flow conditions, suggesting that a non-point 

source of bacteria possibly from livestock may 

enter the system. Conversely, nutrient concentrations did not vary with flow and were similar to 

concentrations reported for undeveloped sites in 

the Springfield Plateau and Ozark aquifers in 

northern Arkansas and southern Missouri. Deuterium and oxygen-18 data show that the Hughes 

Spring discharge is representative of direct precipitation and not influenced by water enriched in 

oxygen-18 through evaporation. Discharge data 

show that Hughes Spring is dominated by conduit 

type ground-water flow, but a considerable component of diffuse flow also exists in the groundwater system. Carbon-13 data indicate a substantial component of the recharge water interacts with 

the surface material (soil and regolith) in the 

recharge area before entering the ground-water 

system for Hughes Spring. Tritium data for 

Hughes Spring indicate that the discharge water is 

a mixture of recent recharge and sub-modern water 

(recharged prior to 1952).

Stark Spring supplies water for the city of 

Cushman, Arkansas, and the surrounding area. 
2 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

The mean annual discharge for Stark Spring was 

0.5 and 1.5 cubic feet per second for water years 

2001 and 2002, respectively. The discharge and 

water-quality data show the ground-water system 

for Stark Spring is dominated by rapid recharge 

from surface runoff and mainly consists of a conduit-type flow system with little diffuse-type flow. 

Analyses of discharge data show that the estimated 

recharge area (0.79 square mile) is larger than the 

surface drainage area (0.34 square mile). Groundwater tracer tests and the outcrop of the Boone 

Formation indicate that most of the recharge area 

extends outside the surface drainage area.

Similar to Hughes Spring, the geochemistry 

of Stark Spring varied with flow conditions. Calcite saturation indices, total dissolved solids concentrations, and hardness demonstrate noticeable 

differences with flow conditions reflecting the 

reduced residence time and interaction of the 

recharge water with the source rock at higher discharges for Stark Spring. In contrast to Hughes 

Spring, concentrations of fecal indicator bacteria 

demonstrated a decrease during high-flow conditions, and this dilution effect may reflect the lack 

of pastureland or sources of non-point contamination in the recharge area. Nutrient concentrations 

did not vary with flow. Nitrite plus nitrate concentrations were less than concentrations reported for 

undeveloped sites in the Springfield Plateau and 

Ozark aquifers in northern Arkansas and southern 

Missouri, and concentrations of phosphorus and 

orthophosphorus were slightly higher. Tritium 

data show that the discharge water is a mixture of 

recent recharge and sub-modern water (recharged 

prior to 1952). 

Recharge to Evening Shade and Roaring 

Springs originate from water entering geologic 

formations in the Ozark aquifer. The springs provide the water supply for the communities of 

Evening Shade and Cherokee Village, respectively, and the surrounding areas. The mean annual 

discharge for water years 2001 and 2002 for 

Evening Shade Spring was 1.44 and 1.24 cubic 

feet per second, respectively. Roaring Spring had 

an average flow of 5.7 cubic feet per second for the 

period of record (July 2001 to October 2002). Little variation in discharge and temperature was evident during high-flow events and throughout the 

monitoring period for both springs, reflecting the 

contribution of flow from the Ozark aquifer. As a 

result, a local recharge area could not be delineated, as the area could include relatively remote 

locations where geologic formations composing 

the Ozark aquifer are exposed and have sufficient 

porosity and hydraulic conductivity to convey 

water that falls as precipitation to the subsurface. 

Ground-water flow directions also demonstrated 

regional flow patterns in each study area from 

water-level contour maps. 

Analyses of major ion concentrations for 

Evening Shade Spring and Roaring Spring indicated that the source water is a calcium bicarbonate type from a dolomitic mineralogy 

representative of the Ozark aquifer. Nutrient concentrations generally were lower than Hughes and 

Stark Springs. Fecal indicator bacteria were not 

detected at Evening Shade Spring and were 

detected in only one sample from Roaring Spring. 

Tritium data show that the discharge water for 

Evening Shade Spring is a mixture of recent 

recharge and sub-modern water (recharged prior to 

1952) and the discharge water for Roaring Spring 

was of relatively modern age (recharge within less 

than 5 to 10 years).

INTRODUCTION

Hughes Spring, Stark Spring, Evening Shade 

Spring, and Roaring Spring are primary municipal 

water supplies for several communities in north-central 

Arkansas. However, the extent and location of the 

recharge areas that contribute water to these four public 

drinking-water supply springs were unknown. The 

hydrogeologic framework of the area contains karst terrain (Imes and Emmett, 1994). Springs located in karst 

regions are particularly vulnerable to contamination 

(White, 1988; Younos and others, 2001; Taylor and 

McCombs, 1998) and present great challenges concerning resource protection. The karst ground-water 

system can have a close connection with the surface, 

with short travel times and flow paths from recharge 

areas to discharge in springs. Shallow ground-water 

systems predominated by fracture or conduit flow can 

be extremely problematic in areas of urban and agricultural land use, and may be subject to rapid input of sur-
Introduction 3

face contaminants and rapid transport of these 

contaminants to wells and springs with little opportunity for natural attenuation processes to occur. Many 

communities and towns in Arkansas have lost the use 

of springs that discharge shallow ground water because 

of surface-derived contamination. 

The problems of delineating the recharge area 

and determining ground-water characteristics of karstic 

systems are numerous. Unlike surface watersheds, 

which have boundaries defined by topography, groundwater basins in karst terrains are controlled by subsurface permeability distributions that are poorly characterized, difficult to predict, non-homogeneous, and 

anisotropic. In karst terrains, the position of subsurface 

ground-water divides, or recharge area boundaries, 

may depend on the hydraulic gradient and orientation 

of widened joints, fractures, and bedding planes in the 

bedrock, and may not correspond to topographic highs 

or surface-drainage boundaries. Furthermore, karst 

characteristics can develop at various depths and as a 

result, subsurface ground-water divides during high 

flows may not coincide with divides during base-flow 

conditions. Subsurface flow in karst terrain can vary 

between two types of flow regimes including conduit 

and diffuse flow types. Conduit flow refers to rapid 

ground-water flow through solution openings with 

diameters ranging from inches to tens of feet. Flow is 

usually turbulent and velocities are commonly on the 

order of feet per second. Diffuse flow refers to groundwater flow in small fractures and pores with small, 

interconnected openings. Diffuse flow can be described 

by Darcy’s Law and has much lower velocities than 

conduit flow. 

In October 2000, a study was begun by the U.S. 

Geological Survey (USGS) in cooperation with the 

Arkansas Department of Health to characterize the 

hydrogeology and extent of the recharge area for 

Hughes, Stark, Evening Shade, and Roaring Springs. 

Characterization of the recharge areas was important 

because of the karst terrain in northern Arkansas. Also, 

land use near the springs, including areas suspected to 

lie within the spring recharge areas, included activities 

with potentially harmful effects to spring water quality. 

Potential effects could result from urban development 

including leakage from underground fuel storage tanks, 

agricultural development including runoff from animal 

feeding operations, and domestic development including discharges from underground septic systems. 

Resource management needs, including preservation of 

the health and safety of the people who rely on the 

resource, dictate that the extent of the recharge area and 

approximate time of travel for constituents moving 

from the recharge area to the spring be characterized. 

These data will help water managers to develop plans 

to protect the recharge area from contamination related 

to land use and enable planned response to acute effects 

such as spills. 

Hughes Spring, Stark Spring, Evening Shade 

Spring, and Roaring Spring supply the public drinking 

water to the communities of Marshall (population 

1,313) in Searcy County, Cushman (population 461) in 

Independence County, and Evening Shade (population 

465) in Sharp County, and Cherokee Village (population 4,648) in Sharp and Fulton Counties, respectively 

(fig. 1; Arkansas Institute for Economic Advancement, 

2003). Including the surrounding area, the total population served by the four public supply springs is approximately 11,200. Between 2001 and 2012 the population 

is projected to increase 15 percent in Searcy County, 10 

percent in Independence County, 15 percent in Sharp 

County, and 14 percent in Fulton County (Arkansas 

Institute for Economic Advancement, 2003). As 

growth continues, land-use changes may cause the 

threat to shallow ground water to intensify, and the protection of the limited water resources in the area will be 

increasingly critical to the health and safety of the local 

population. 

Purpose and Scope

The purpose of this report is to describe the 

hydrogeologic characteristics, including the extent of 

the recharge areas, of Hughes, Stark, Evening Shade, 

and Roaring Springs. Information pertaining to each 

spring can be used to enable development of effective 

management plans to protect these water resources and 

public health. Continuous discharge, temperature, and 

precipitation data were collected at the four springs for 

a 2-year period (October 2000 to October 2002) to 

determine flow characteristics and recharge area. An 

assessment of the local geology through previous mapping, borehole geophysics, and field investigation was 

completed in each study area to determine controls on 

the ground-water flow. Water-level contour maps were 

constructed from well and spring data in each study 

area to show the configuration of the water table and 

determine ground-water flow directions. Qualitative 

dye tracing also was completed in 2002 to help define 

the recharge area and estimate ground-water flow 

velocities. Water-quality samples were collected dur-
4 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 1. Locations of springs and study areas.

Hughes

Spring

Stark

Spring

Evening Shade

Spring

Roaring

Spring

Marshall

Evening

Shade

Cushman

Batesville

Ash

Flat

Cherokee

Village

Hardy

Salem Plateau

Springfield

Plateau

Boston Mountains

Izard

Stone

Sharp

Searcy

Fulton

Marion

Baxter

Van Buren Cleburne

Independence

Arkansas

Base from U.S. Geological Survey

digital data, 1:100,000

Missouri

Arkansas

0 10 20 Miles

0 10 20 Kilometers

35°30'

36°30'

92°30' 91°30'

EXPLANATION

Spring

Study Area
Methods of Investigation 5

ing September 2001 through October 2002 at each 

spring to determine the geochemistry of the contributing geologic units, and the susceptibility of the springs 

to contamination.

Acknowledgments

The author would like to thank the operators of 

the public water systems examined in this report for 

their assistance and cooperation: Kevin Elliot, Marshall 

Water Works; Don Riley, Cushman Water Works; Pat 

Shell, Evening Shade Water Works; and Steve Rose, 

Cherokee Village Water Works. The author would like 

to especially thank the many residents that allowed 

access to their wells and springs used in this study.

METHODS OF INVESTIGATION

An integrated approach to determine the hydrogeologic characteristics and the extent of the local 

recharge areas of the four public water-supply springs 

incorporated methods of hydrology, structural geology, 

geomorphology, geophysics, and geochemistry. These 

independent methods of investigation are tools that can 

provide evidence for effectively describing the behavior of hydrologic systems.

Hydrogeologic Assessment

Several methods were used to determine the 

hydrogeologic characteristics of each study area. 

USGS 1:24,000-scale topographic maps were used to 

determine preliminary ground-water flow boundaries 

and recharge areas based solely on the configuration of 

the land-surface topography. Geologic maps created at 

a 1:24,000-scale (E.E. Glick, U.S. Geological Survey, 

unpub. data, 1973) were used to determine geologic 

units exposed in the study areas. Geomorphic and topographic data from existing maps were gathered and 

assessed to determine surficial controls on infiltration, 

ground-water flow pathways, and boundaries to 

ground-water flow. 

A field inventory of karst features (caves, sinkholes, sinking streams, and enlarged vertical fractures 

and bedding planes), wells, and springs also was conducted in each study area. Karst features provided 

information on the connection of the ground-water system to the land surface. Water levels in wells and spring 

discharge altitudes were used to determine the configuration of the water table, flow characteristics in the 

recharge areas, and ground-water tracer injection and 

monitoring points. 

In addition, several wells were used for borehole 

geophysical surveys. Borehole geophysical surveys 

conducted in 11 wells within the study areas provided 

information about the lithology, distribution of permeability, and nature of vertical flow within the groundwater system. All inventoried wells drilled to depths 

greater than 100 ft below land surface and not currently 

used for water supply were surveyed. A variety of geophysical parameters were measured including caliper 

measurements, fluid resistivity and temperature, natural gamma, long and short normal resistivity, and lateral and single-point resistivity. Heat-pulse flowmeter 

and acoustic televiewer tools also were used on several 

of the wells. Structural geology data from field investigation and geologic maps were inventoried, compiled, 

and reviewed along with the borehole geophysical data 

to characterize the distribution of conduits and configuration of the geologic units within the study areas. 

Discharge, Temperature, and Precipitation 

Monitoring

To determine flow characteristics and aid in the 

estimate of the recharge area, the four springs were 

instrumented to measure discharge, water temperature, 

and precipitation. Each spring had a structure such as a 

springhouse or weir to control the stage-discharge relation. The stage (water-level elevation) was monitored 

and used in conjunction with periodic manual discharge measurements to define the stage-discharge 

relation for October 2001 to October 2002. For Stark 

Spring, discharge measurements were made only when 

the discharge was large enough to top the overflow weir 

that allows water to flow out of the springhouse. For 

most of the monitoring period, the discharge did not 

exceed the capacity of the withdrawal pumps and did 

not flow from the springhouse. During these periods, 

daily discharge was computed based on the volume of 

the springhouse holding tank at various stages and the 

withdrawal rates of the multiple pumps at the spring 

which were measured with a passive flow device. The 

passive flow device also was used at the three other 

springs to quantify the amount of water that was withdrawn at each spring.

The daily discharge was estimated for Hughes 

Spring for the period of November 2001 to September 
6 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

2002. The weir constructed to control the stage-discharge relation was washed out twice by high-flow 

events (November 28, 2001 and January 31, 2002). The 

lack of a stable control structure prevented the development of a good stage-discharge relation. Therefore, the 

daily discharge was estimated using succeeding discharge measurements to develop a series of stage-discharge relations.

An analysis of base flow was conducted on the 

discharge data at each spring. Base flow was separated 

from excess runoff on a daily basis using the base flow 

index (BFI) program described in Wahl and Wahl 

(1995). The BFI program uses the Institute of Hydrology method of base flow separation, which divides the 

water year (October 1 to September 30) into 5-day 

increments and identifies the minimum flow for each 

increment. Minimum flow of each increment is compared to adjacent minimums to determine turning points 

on the base-flow hydrograph. If 90 percent of a given 

minimum is less than both adjacent minimums, then that 

minimum is a turning point. Straight lines are drawn 

between the turning points to define the base-flow 

hydrograph. The area beneath the hydrograph is the estimate of the volume of base flow for the period. The ratio 

of the base flow volume to total flow volume is the base 

flow index.

One method used to estimate the subsurface-flow 

regime (conduit or diffuse flow) in the aquifer system 

contributing to a spring is to calculate the ratio of the 

peak discharge to base-flow discharge. White (1988) 

presented a range of ratio values of 1 to 2 for slowresponse (diffuse flow) springs; 7 to 10 for intermediateresponse (diffuse and conduit flow) springs; and greater 

than 40 for fast-response (conduit flow) springs. The 

highest daily discharge for the year was chosen for the 

peak discharge and the lowest daily discharge was used 

for the base-flow discharge to calculate the ratio at each 

spring.

Because of the runoff characteristics and interactions of ground water and surface water in the Stark 

Spring study area, further analysis of discharge was conducted. The local-recharge area was estimated from the 

discharge record using a water-balance approach for 

individual storms. The water-balance approach accounts 

for the inputs, outputs, and storage of water in the system (White, 1988; Pavlicek, 1996; Vandike, 1994). Several storms were selected for analysis that had short 

intense precipitation events resulting in a substantial 

peak in the spring discharge. The volume of discharge 

attributed to the storm runoff was determined by removing the volume of base-flow discharge determined by 

the BFI program. Precipitation was monitored using a 

single automatic tipping bucket gage located at the 

spring. The volume of precipitation was determined by 

uniformly applying the recorded precipitation to the 

estimated recharge area (inflow) and then equating it to 

the volume of storm runoff discharging from the spring 

(outflow). Losses due to evapotranspiration, soil absorption, and interception were considered, but were not 

extensively quantified. A 10 percent reduction in 

recharge volume was used to estimate the losses. The 10 

percent reduction was used based on field observations 

of little surface runoff during precipitation events, generally thin soil mantle on the bedrock, and the welldeveloped karst features (sinkholes, sinking streams, 

enlarged fractures) in the area. The greatest loss in 

recharge volume is probably because of interception by 

vegetation in the recharge area with minimal losses due 

to evapotranspiration because of the short duration of 

the storms. The calculated recharge area was adjusted 

using equation 1 until the inflow volume minus losses 

was equal to the outflow volume:

(1)

where A is the estimated recharge area, in square miles,

Vr is the total storm runoff volume from the 

spring discharge, in cubic feet,

P is the total storm precipitation, in inches, and

L is the total losses in the storm precipitation 

(0.10 × P), in inches.

Water temperature also was monitored at each 

spring to detect mixing of surface runoff and ground 

water in the spring discharge. While water temperatures 

during base-flow conditions may remain constant, 

inputs to the ground-water system during runoff events 

approximate the surface and air temperatures at the time 

of the event, and changes in water temperature provide 

an indicator of the connection with the surface-water 

system.

Water-Level Mapping

Water-level contour maps were constructed from 

ground-water level measurements and land-surface altitude data obtained from the wells and springs inventoried in each area. Well and spring altitudes were 

obtained from USGS 1:24,000-scale topographic maps. 

Wells inventoried for this study commonly were conA 4.3 10–7 ( ) ×

Vr

( ) P L – = -----------------
Methods of Investigation 7

structed with surface casing installed to a depth of 30 

ft, with open borehole below that depth. Therefore, all 

the hydrogeologic units penetrated by the open borehole potentially contribute to water levels in the wells. 

The water-level contour maps were constructed using 

water-levels measured in the wells and altitudes of the 

spring discharge. The contour interval varied in each 

study area depending on the number of control points 

and range of altitude for each area. A water-level contour map of the Stark Spring study area was not constructed because of few control points.

Qualitative Ground-Water Tracing

The preliminary recharge area delineation was 

tested and improved using ground-water tracing techniques. Qualitative tracer tests were conducted from 

January to June 2002 during high-flow conditions to 

identify ground-water flow paths and velocities and 

confirm the locations of inferred ground-water-basin 

boundaries. Qualitative tests identify positive or negative detection of tracers at measured sites and do not 

quantify the concentrations of the tracers. In each 

ground-water tracer test, a fluorescent dye or optical 

brightener was injected into the aquifer using natural or 

induced flow into open sinkholes, swallow holes, sinking streams, or wells (fig. 2). 

Four separate types of tracers were used including tinopal CBSX optical brightener (color index (C.I.) 

fluorescent brightener 351), eosine OJ (C.I. acid yellow), fluorescein (C.I. acid yellow 73), and rhodamine 

WT (C.I. acid red 388). Different tracers were used in 

the study to allow for multiple simultaneous injections. 

Resurgent tracers were recovered on passive charcoal 

detectors that generally were collected and exchanged 

at 1- to 7-day intervals. Tracers were input at various 

points inside and outside of the preliminary recharge 

areas. Collection sites were monitored until tracers 

were no longer observed at any of the sites. Background fluorescence was monitored at every collection 

site prior to each injection. 

Figure 2. Injection of eosine OJ dye into a swallow hole in the Hughes Spring area (photograph by Jaysson Funkhouser, U.S. 

Geological Survey).
8 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

The passive dye detectors consisted of activated 

charcoal contained in a nylon mesh screen. The detectors were placed in the center of flow at springs or suspended in wells using a nylon line or wire. The dye was 

extracted from the passive detectors by elutriation in a 

5 percent ammonium hydroxide and 70 percent propanol solution as described in Mull and others (1988). 

Positive or negative determination of tracer recovery 

was made using a scanning spectrofluorophotometer as 

described by Duley (1986).

Two tracer tests were conducted in the Hughes 

Spring study area that included a total of seven separate 

injections at different locations. One test also was conducted in the Stark Spring study area that included four 

injections and one test in the Evening Shade Spring 

study area that included three injections. Tracer tests 

were not conducted in the Roaring Spring study area 

because of the lack of injection sites.

Water Quality 

Water-quality samples were collected at each 

spring to determine the geochemistry of the contributing geologic units and the susceptibility of the spring to 

contamination. Samples were collected during baseflow and high-flow conditions because ground-water 

quality in karst systems has been shown to be 

extremely variable, and dissolved constituent loads 

(including contaminants) during storm events can be 

orders of magnitude different than during base-flow 

conditions. Additional samples also were collected 

from several wells and springs in the Evening Shade 

and Roaring Springs areas to identify contributing 

aquifers to the springs through geochemical similarities. 

All samples collected from the four springs were 

analyzed for major ions, selected trace constituents, 

nutrients, fecal indicator bacteria, wastewater constituents, stable isotopes, and radiogenic isotopes (table 1). 

Measurements of water temperature, dissolved oxygen, 

specific conductance, pH, and alkalinity also were 

completed during the collection of each sample. Samples were collected and measurements were made 

using protocols described in Wilde and Radke (1998), 

Wilde and others (1998a, 1998b, 1998c, 1999a, and 

1999b), and Meyers and Wilde (1999).

The major ion and trace constituent data provided useful information in determining the type of 

source rock, and flow characteristics. Cation and anion 

concentrations are plotted as percentages of total milliequivalents per liter on trilinear diagrams to determine water composition type and to examine 

similarities between samples (Hem, 1989). Samples 

collected for this report were compared to other samples collected from previous studies in northern Arkansas and southern Missouri. Water-quality data for wells 

and springs identified as being contributed by water 

from the Springfield Plateau aquifer or Ozark aquifer 

were obtained from the USGS National Water Information System (NWIS) database. The ratio of calcium to 

magnesium, as molar equivalents per liter, was calculated to determine the mineralogy of the rocks that 

influence the ground-water chemistry. For waters in 

contact with dolomite, the molar ratio of calcium to 

magnesium is approximately 1. For water in contact 

with limestone, ratios have been observed to vary from 

3 to greater than 10 (White, 1988). 

Sample data also were analyzed using PHREEQC software, (Parkhurst and Appelo, 1999) to calculate calcite saturation indices (SIcalcite) using the 

following formula:

SIcalcite = log(IAP/KT) (2)

where IAP is the ion activity product of the mineral 

(calcite) and KT is the thermodynamic equilibrium constant at a given temperature. A value of SIcalcite equal 

to 0 indicates that the water sample is saturated with 

calcite. A value for SIcalcite greater than 0 indicates that 

the sample is supersaturated with calcite and a value 

less than 0 would indicate a water sample was undersaturated with respect to calcite. The SIcalcite can be used 

to determine hydrogeologic characteristics of the 

spring water. For example, water flowing diffusely 

through carbonate rocks or water flowing through 

small fractures quickly becomes saturated with respect 

to calcite. Conversely, water moving through large 

fractures and conduits requires longer flow paths and 

residence times to become saturated with respect to calcite (Adamski, 2000).

Samples were analyzed for several species of 

nitrogen and phosphorus (table 1) to determine potential contamination from local source water during different flow conditions. Nutrients in ground water occur 

naturally at low concentrations in northern Arkansas 

(Adamski, 1997). Anthropogenic sources of nutrients 

such as sewage discharge, fertilizers, animal waste, and 

septic tanks can increase concentrations of nitrogen 

and phosphorus above normal ambient levels. Species 

of nitrogen, such as nitrate, are undesirable in domestic 
Methods of Investigation 9

Table 1. List of water-quality properties and constituents collected and analyzed at Hughes, Stark, Evening Shade, and 

Roaring Springs

Field parameters 3-beta-Coprostanol Isoquinoline

Water temperature 3-Methyl-1(H)-indole (Skatole) Menthol

Dissolved oxygen 3-tert-Butyl-4-hydroxy anisole (BHA) Metalaxyl

Specific conductance 4-Cumylphenol Methyl salicylate

pH 4-n-Octylphenol Metolachlor

Alkalinity 4-tert-Octylphenol N,N-diethyl-meta-toluamide (DEET)

Major ions and trace constituents 5-Methyl-1H-benzotriazole Naphthalene

Bicarbonate Acetophenone Nonylphenol, diethoxy- (total)

Calcium Acetyl hexamethyl tetrahydronaphthalene (AHTN) Octylphenol, diethoxyMagnesium Anthracene Octylphenol, monoethoxySodium Anthraquinone para-Nonylphenol (total)

Potassium Benzo[a]pyrene para-Nonylphenol (total)

Chloride Benzophenone Pentachlorophenol

Sulfate beta-Stigmastanol Phenanthrene

Silica beta-Stigmastanol Phenol

Bromide Bisphenol A Prometon

Fluoride Bromacil Pyrene

Iron Bromoform Tetrachloroethylene

Manganese Caffeine Tri(2-butoxyethyl)phosphate

Strontium Camphor Tri(2-chloroethyl)phosphate

Boron Carbaryl Tributyl phosphate

Nutrients Carbazole Triclosan

Ammonia Chlorpyrifos Triethyl citrate (ethyl citrate)

Ammonia plus organic nitrogen Cholesterol Triphenyl phosphate

Nitrite plus nitrate Cotinine Tris(dichlorisopropyl)-phosphate

Nitrite d-Limonene Stable isotopes

Phosphorus Diazinon Deuterium

Orthophosphorus Dichlorvos Oxygen-18

Fecal indicator bacteria Equilenin Carbon-13

Escherichia coli bacteria Estrone Strontium-87

Fecal coliform bacteria Diazinon Radiogenic isotopes

Fecal streptococci bacteria Ethynyl estradiol Tritium

Wastewater constituents Fluoranthene Carbon-14

1,4-Dichlorobenzene Hexadydrohexamethyl-cyclopentabenzopyran (HHCB)

1-Methylnaphthalene Indole

17-beta-Estradiol Isoborneol

2,6-Dimethylnaphthalene Isophorone

2-Methylnaphthalene Isopropylbenzene
10 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

or public-water supply at high concentrations because 

of the potential health hazards, particularly for infants 

(Davis and Bell, 1998). Because of the potential health 

risks associated with nitrate, the U.S. Environmental 

Protection Agency (USEPA) has established a Maximum Contaminant Level (MCL) of 10 milligrams per 

liter of nitrate as nitrogen in public-drinking water supplies (U.S. Environmental Protection Agency, 2002). 

Samples were collected and analyzed for fecal 

indicator bacteria, which are measures of the sanitary 

quality of water. Indicator bacteria typically are not disease causing, but are correlated to the presence of 

water-borne pathogens. Sources of fecal indicator bacteria can include untreated municipal wastewater-treatment effluents; septic tanks; animal wastes from 

feedlots, barnyards, and pastures; and manure application areas. The fecal indicator bacteria used in this 

report are fecal coliform, fecal streptococci, and 

Escherichia coli (E. coli), all of which are restricted to 

the intestinal tracts of warm-blooded animals and can 

provide direct evidence of fecal contamination from 

warm-blooded animals and the possible presence of 

pathogens (Davis and Bell, 1998). The presence of 

fecal indicator bacteria would demonstrate a connection from the spring to local sources of the bacteria. 

Samples also were collected and analyzed at 

each spring for a number of wastewater constituents 

(table 1). The wastewater constituents included a wide 

range of anthropogenic compounds that typically pass 

through conventional septic tanks or sewage- treatment 

systems. These compounds included fumigants, antioxidants, detergent metabolites, disinfectant antimicrobials, hormones, and caffeine. 

Stable isotopes were used in the characterization 

of the geochemical evolution of the spring water. Deuterium and oxygen-18 ratios (δD and δ18O, respectively) were reported in per mil, or parts per thousand, 

relative to Vienna Standard Mean Ocean Water 

(VSMOW). The δD and δ18Ο data can be used to 

determine changes in the source water caused by evaporation between the time the precipitation fell on the 

ground surface and was discharged at each spring. For 

example, waters with δD and δ18Ο values that do not 

follow the δD and δ18Ο relation of the VSMOW can 

indicate that the source water resided at the land surface 

in lakes, ponds, and streams and were subjected to 

evaporation prior to infiltration into the aquifer system. 

Variations because of the isotopic composition of local 

precipitation also may cause the δD and δ18Ο to vary 

from the VSMOW and have a local meteoric water signature. δD and δ18Ο samples collected for this report 

were compared to a local meteoric line approximated 

by other samples collected from 160 wells and springs 

in northern Arkansas and southern Missouri for previous studies. These data were obtained from the USGS 

NWIS database.

Carbon-13 (δ13C) data were used to characterize 

the source water by examining the proportions of inorganically- and organically-derived carbon in the system. The proportions of inorganically- and organicallyderived carbon in the spring discharge can be used to 

infer the path of water from the recharge source to the 

spring discharge. As recharge waters percolate through 

soils and regolith during infiltration into the groundwater system, soil CO2 comprising organically-derived 

carbon from degradation of soil organic matter, is dissolved and increases the acidity of the water. As water 

enters the ground-water system, acidity is buffered as 

calcium carbonate from the source rock (limestone or 

dolomite) is dissolved, increasing the proportion of 

inorganically-derived carbon in the water. Typical 

δ13C values of organically-derived carbon found in 

soils or ground water in northern Arkansas are approximately -24 per mil (Clark and Fritz, 1997; P.D. Hays, 

U.S. Geological Survey, oral commun., 2003). The 

value of organically-derived δ13C for soils can be used 

to estimate the inorganically- and organically-derived 

carbon proportions in the spring discharge, assuming 

an initial value of 0 per mill for inorganic δ13C, using 

the following equations:

(3)

(4)

where is the percentage of inorganically-derived δ13C,

 is the δ13C value from sample analyses, and

 is the percentage of organically-derived 

δ13C.

Samples were analyzed for radiogenic isotopes 

including tritium and carbon-14. These were used to 

determine the relative age of the water discharging 

from each of the springs. The age refers to the period of 

time that has elapsed since the water moved deep 

enough into the ground-water system to be isolated 

from the atmosphere. Tritium values, given in tritium 

units (TU) are used to age date more recent waters (less 

%δCinorganic 1 δCmeasured δCorganic = [ ] – ( ) ⁄ × 100%

%δCorganic = 100% %– δCinorganic

%δCinorganic

%δCmeasured

%δCorganic
Spring Characterization 11

than 40 years) and carbon-14 data, given in percent 

modern carbon (PMC) are used to age date older waters 

(50 to 30,000 years). The tritium values were used to 

qualitatively date the discharge from each spring using 

ranges of age for given tritium values from Clark and 

Fritz (1997) (table 2).

SPRING CHARACTERIZATION

Hughes Spring

Study Area Description

The Hughes Spring study area lies in the Ozark 

Plateau, Salem Plateau, and Boston Mountains physiographic provinces (fig. 1). The area is dominated 

mainly by karstic limestones of Pennsylvanian to 

Ordovician age. The altitude of the study area ranges 

from 531 to 1,785 ft above NGVD of 1929. Land use in 

the area (Vogelmann and others, 2001) consists primarily of deciduous and evergreen forest (60 percent) and 

agricultural land (39 percent). Almost all of the agricultural land is utilized as pasture. Only a small portion of 

the study area is covered by urban land use (1 percent).

A humid, temperate climate is characteristic of 

the study area. The annual mean temperature recorded 

at Marshall (fig. 1) in calendar years 2001 and 2002 

was 12 °C, which was below normal (-2 °C) based on 

a 30-year period from 1961 to 1990 (Hoare, 1996). The 

annual rainfall recorded at Marshall was 36 inches for 

2001 and 58 inches for 2002 (National Oceanic and 

Atmospheric Administration, 2001; 2002). The average annual rainfall is 43 inches (Hoare, 1996). 

Hydrogeology

The study area for Hughes Spring includes the 

Western Interior Plains confining system and the 

Springfield Plateau and Ozark aquifers. Exposures of 

geologic units of the Springfield Plateau aquifer dominate the area, smaller portions of the Ozark aquifer are 

exposed in the northern part of the study area, and portions of the Western Interior Plains confining system 

are exposed in the southern portion of the study area 

(figs. 3 and 4). Measurements of outcrop strike and dip 

(fig. 4) and geophysical logs indicate that units generally dip south-southeast by 3 to 12 degrees in the study 

area. The only large structural feature is a fault, located 

in the southern portion of the study area. 

The Western Interior Plains confining system 

contains the youngest geologic units which are exposed 

in the southern portion of the study area at higher elevations. The units include the Pennsylvanian-age 

Bloyd Shale and Hale Formation, and Mississippianage Pitkin Limestone, Fayetteville Shale, Batesville 

Sandstone, and Moorefield Formation including the 

Ruddell Shale Member (figs. 3 and 4).

The geologic units of the Springfield Plateau 

aquifer are extensively exposed in the study area and 

consist of the Mississippian-age Boone Formation 

including the St. Joe Limestone Member. The Springfield Plateau aquifer typically is separated from the 

underlying Ozark aquifer by the Ozark confining unit 

composed of Devonian-age Chattanooga Shale in areas 

of northern Arkansas (fig. 3). Borehole geophysical 

surveys in several wells (fig. 5) show the Chattanooga 

Shale (Ozark confining unit) was thin or absent in the 

study area.

The Ozark aquifer is exposed at low elevations in 

stream valleys in the northern portion of the study area. 

Geologic formations that compose the Ozark aquifer 

and are exposed in the study area include Devonianand Silurian-age limestone units, and Ordovician-age 

Cason Shale, Fernvale, Kimmswick, and Plattin Limestones, Joachim Dolomite, St. Peter Sandstone, and 

Everton Formation. 

Table 2. Tritium concentrations with relative ages (from 

Clark and Fritz, 1997)

[<, less than; >, greater than]

Tritium

concentration,

in tritium units Relative age

<0.8 Sub-modern ground water recharged prior to 1952 

0.8 - 4 Mixture between sub-modern waters and recent

recharge

5 - 15 Modern water (<5 to 10 years)

15-30 Some “bomb” tritium present or some component

of recharge from the 1960s or 1970s

>30 Considerable component of recharge from the

1960s or 1970s

>50 Dominantly recharged in the 1960s
12 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 3. Stratigraphic column with descriptions of lithologic and geohydrologic properties of the Western Interior Plains 

confining system and the Ozark Plateaus aquifer system within Arkansas (modified from Pugh, 1998 and McFarland, 1998).

Formation Member

Black to dark-gray shale interbedded with

limestone and some sandstones 0 -1,170 ft1,3

Prairie Grove

Cane Hill

Fine- to coarse-grained, oolitic, bioclastic

limestone 0 - 400 ft1,3

Black, fissile, concretionary, clay shale

interbedded with fine-grained limestones 0 - 1,634 ft1,3

Fine- to coarse-grained sandstone with thin

shales 0 - 200 ft3

Boone

Formation

St. Joe

Limestone

Gray, fine- to coarse-grained fossiliferous

limestone interbedded with chert 300 - 370 ft1,3 Springfield Plateau

Aquifer

Black, fissile clay shale that weathers into

thin flakes 0 -85 ft1,3 Ozark Confining

Unit

Thin, very sandy limestone with few fossils 0 - 4 ft 3

Fine-grained, fossiliferous, dolomitic

limestone with some chert 0 - 265 ft1,3

Gray-green to red micrite or sparsely

fossiliferous biomicrite 5 - 20 ft3

Coarse-grained, highly fossiliferous

limestone 0 -100 ft3

Massive, coarsely crystalline, crinoidal

limestone 0 -100 ft1,3

Thin to massive, fine- to coarse-grained,

bioclastic limestone 0 -180 ft1,3

Thin bedded, very fine-grained, micritic

limestone 0 -367 ft1,3

Fine-grained dolostone and dolomitic

limestone with thin beds of shale 0 -100 ft1,3

Massive bedded, medium- to fine-grained,

well-rounded, friable sandstone 0 -175 ft1,3

Highly variable with mixtures of dolostone,

sandstone, and limestone 0 -1,205 ft1,3

Fine-grained, limy argillaceous dolostone

with thin beds of shale and sandstone 0 - 420 ft1,2,3

Two different types of dolostone 0 - 527 ft1,2,3

Fine-grained, crystalline dolostone and

considerable chert 100 - 496 ft1,2

Cherty dolostone, dolomitic sandstone and

scattered sandstone intervals 130 - 455 ft1,2

Gasconade

Dolomite

Gunter

Sandstone

Cherty dolostone, sandstone (Gunter) 300 - 600 ft1,2

Western Interior

Plains Confining

System

Ruddell

Shale

Brassfield

Limestone

Pitkin Limestone

Fayetteville Shale

Batesville Sandstone

Chattanooga Shale

Includes phosphatic sandstone and shale,

oolitic limestone, fossiliferous limestone

(Brassfield) and sandy calcareous shade

Jefferson City Dolomite

Roubidoux Formation

Moorefield

Formation

Black calcareous and siliceous shale to a

dark fissile clay shale

St. Peter Sandstone

Everton Formation

Powell Dolomite

Cotter Dolomite

Fernvale Limestone

Kimmswick Limestone

Period

Bloyd Shale

Dark-gray silty shales interbedded with

siltstones and limy sandstones 0 - 980 ft Hale 1,3

Formation

Geologic Unit Name Description Thickness

Carboniferous

0 - 300 ft3

Hydrogeologic unit

or system

Devonian

Middle

Ordovician

Pennsylvanian Mississippian

Silurian

Cason Shale

Late

Ozark Aquifer

0 - 45 ft1,3

Early

Plattin Limestone

Joachim Dolomite

Clifty Limestone

Penters Chert

Lafferty Limestone

St. Clair Limestone

Ozark Plateaus Aquifer System

Caplan (1957)

Caplan (1960)

McFarland (1998)

1

2

3
Spring Characterization 13Figure 4. Geology of the Hughes Spring study area.

Brush

Creek

Creek

Buffalo

River

Rocky

Creek

Bear

Mbn

Mbn

Mbn

Bear

Mfb

Mfb

Mfb

Phc Phc

Phc

Mfb

Mm

Mm

Mm

Ofp

Ofp

Slsb

Slsb

Ocj

Ocj

Ose

Ose

Mp

Mp

Mp

Slsb

Creek

3

6

10

10

HughesSpring

Marshall

8

6

8

4

12

13

65

27

65

74

27

74

0 1 2 Miles

0 1 2 Kilometers

92°42' 92°36'

36°

35°54'

Geology modified from E.E. GlickU.S. Geological Survey, unpub data., 1973Base from U.S. Geological Surveydigital data, 1:100,000

EXP

Mp

Mfb

Mbn

Ofp

Ocj

Ose

10

LPoCoPFBMBLSBMFPCDSEFdSdiSCS

Pbh

Phc

Mm

Slsb
14 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 5. Distribution of wells and springs in the Hughes Spring study area.

Brush

Creek

Creek

Buffalo

River

Rocky

Creek

Bear

W9

W6

W8

W7

W5

W4

W3

W2

W1

W16

W22

W27

W12

W10

W32

W31

W29

W28

W26 W25

W24

W23

W21 W20

W18 W19

W17

W15

W14

W13

W11

S9

S8 S7

S6

S3

S5

S4

S2

S1

S17

S16

S15

S14

S13

S12 S11

S10

65

27

65

74

Marshall

27

74

0 1 2 Miles

0 1 2 Kilometers

36°

35°54'

92°42' 92°36'

Unknown

Cane Hill Member of

the Hale Formation

Batesville Sandstone

Boone Formation

Fernvale and Plattin

Limestone

St. Peter Sandstone/

Everton Formation

Powell Dolomite

Springs

Wells with geophysical

surveys

Wells and Geologic unit at total depth (Associated site identifier refer to table 3)

EXPLANATION

Base from U.S. Geological Survey

digital data, 1:100,000

Water-level data indicate a hydrologic connection exists between the Springfield Plateau aquifer and 

the Ozark aquifer because of the weak presence of the 

Ozark confining unit. Well-developed karstic features 

that provide vertical connection between the two aquifers also were observed in the study area. Hughes 

Spring discharges from fractures in units of the Ozark 

aquifer, although most of the water probably originates 

from the overlying Springfield Plateau aquifer (fig. 6).

The karst features observed in the Hughes Spring 

study area occur mainly in the Boone Formation. These 

features develop as ground water percolates through the 

limestone resulting in the enlargement of fractures 

through the dissolution of the carbonate rock (solution 

channels). Karst features present in the study area 

include solution channels, sinkholes, springs, sinking 

streams, and caves (fig. 4). Four caves and six sinkholes 

were inventoried and enlarged fracture openings were 

evident at the surface throughout the area. No surface 

streams were observed to have perennial flow throughout the year. Brush Creek was observed to have flow 

along its entire length in the study area only during periods of intense rainfall events. During the rest of the 

year, flow was evident only in the streambed near 

spring discharge points.
Spring Characterization 15Figure 6. Conceptual model of ground-water flow to Hughes Spring.

EVERTON FO

ST. PETER SA

FERNVALE LI

BOONE FORM

RUDDELL SHALE MEMBER

OF THE

MOOREFIELD FORMATION

F

BA

P

Hughes

Spring

NORTH 

Brush Creek

;

CASON SHAL

SINKHOLE

SOLUTION

CHANNELS

; ; ;

; ; ;

; ; ; ; 

;

;

EXPLANATIONGeneralized flow direction

of Brush Creek

Generalized ground-water

flow direction
16 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Discharge, Temperature, and Precipitation

The discharge for Hughes Spring varied seasonally and temporally (fig. 7). The mean annual discharges for water years 2001 and 2002 were 2.0 and 5.2 

cubic feet per second (ft3/s), respectively (Brossett and 

Evans, 2003). Mean daily discharge ranged from 

approximately 0.5 to 14 ft3

/s for water years 2001 and 

2002. The spring discharge generally followed precipitation patterns with the highest mean daily discharges 

in the months of December through May and the lowest 

mean daily discharges generally in the months of July 

through November.

Water temperature for Hughes Spring reflected 

seasonal variations throughout the monitoring period 

(fig. 7) and demonstrated considerable changes during 

summer high-flow events (fig. 8). Recorded water temperature ranged from 10.6 °C to 23.2 °C with a mean 

of 14.6 °C (fig. 7). The highest temperatures were 

recorded in the summer (June through August) and fall 

(September through November) with average temperatures at approximately 17 °C for both seasons. The 

winter (January, February, and December) and spring 

(March through May) had lower average temperatures 

of approximately 12 °C and 13 °C, respectively. Large 

water temperature variations corresponded to highflow events (fig. 8).

Figure 7. Daily discharge, rainfall, and water temperature recorded at Hughes Spring.

Oct Feb Jun Oct Feb Jun Oct 

DISCHARGE, IN CUBIC FEET PER SECOND

0.01

0.1

1

10

100

RAINFALL, IN INCHES

0

1

2

3

4

5

6

DATE

TEMPERATURE, IN DEGREES CELSIUS

8

10

12

14

16

18

20

22

24

WATER YEAR 2001 WATER YEAR 2002

Oct Dec Feb Apr June Aug Oct Dec Feb Apr June e e Aug 

Oct Dec Feb Apr June Aug Oct Dec Feb Apr June Aug 

Oct Dec Feb Apr June Aug Oct Dec Feb Apr June Aug 

Water-quality

sample collected

October 15, 2002

TOTAL CALCULATED

MEASURED

ESTIMATED

WATER-QUALITY SAMPLE

BASEFLOW
Spring Characterization 17

Figure 8. Discharge and water temperature data from Hughes Spring for four storm events.

1/26/01 1/28/01 1/30/01 2/1/01 2/3/01 2/5/01 2/7/01

DISCHARGE, IN CUBIC FEET PER SECOND

0

2

4

6

8

10

12

14

16

TEMPERATURE, IN DEGREES CELSIUS

10.0

10.5

11.0

11.5

12.0

DISCHARGE

TEMPERATURE

9/11/01 9/15/01 9/19/01 9/23/01 9/27/01

DISCHARGE, IN CUBIC FEET PER SECOND

0

1

2

3

4

5

TEMPERATURE, IN DEGREES CELSIUS

16

18

20

22

DISCHARGE

TEMPERATURE

7/16/01 7/18/01 7/20/01 7/22/01 7/24/01 7/26/01

DISCHARGE, IN CUBIC FEET PER SECOND

0

1

2

3

4

TEMPERATURE, IN DEGREES CELSIUS

17

18

19

20

21

22

23

24

DISCHARGE

TEMPERATURE

DATE

9/5/01 9/7/01 9/9/01 9/11/01 9/13/01 9/15/01 9/17/01

DISCHARGE, IN CUBIC FEET PER SECOND

0.0

0.5

1.0

1.5

2.0

2.5

3.0

TEMPERATURE, IN DEGREES CELSIUS

17

18

19

20

21

22

DISCHARGE

TEMPERATURE

DATE

Discharge data and base-flow separation analysis 

indicate that although the Hughes Spring discharge is 

dominated by base flow, it responds quickly to surfacerunoff events. On average, the base flow composed 

approximately 67 percent of the discharge volume for 

the period of October 2000 through November 2001. 

However, discharge exceeded base flow by more than 5 

percent during 75 percent of the monitoring period. 

The ratio of annual peak flow to base flow for Hughes 

Spring was calculated as 28 based on the 2001 water 

year data, indicating a fast-response spring (White, 

1988). Further analysis of the discharge data for 

Hughes Spring using a water-balance calculation was 

not conducted because the runoff in Brush Creek was 

not measured. Because Hughes Spring lies within the 

Brush Creek drainage area, the runoff data would be 

required to determine the proportion of runoff discharging through Brush Creek and Hughes Spring to 

estimate the size of the recharge area contributing flow 

to Hughes Spring.

Water-Level Contours

Water-level contours constructed from static 

water levels measured in 27 wells and estimated at 15 

springs representing units of the Springfield and Ozark 

aquifers in calendar year 2001(table 3) generally followed land-surface topography in the area and indicated ground-water flow is generally to the northwest 

towards the Buffalo River with the highest water-level 

elevations occurring in the southeast corner of the study 

area (fig. 9). There was one area of water-level depression in the north-central portion of the study area. The 

depression could reflect a zone of higher permeability 

in lower units penetrated by well W32 (fig. 5). A contour interval of 100 ft was used to account for the variations in water level because of the high topographic 

relief, extensive karst development, and the few data 

points in the study area (fig. 9).
18 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas Table 3. Wells and springs inventoried in the Hughes Spring study area [Geologic unit name refers to the formation from which the spring discharges or the formation at the total depth of the well; USGS, U.S. Geological Survey; ddmmss, 

not located within study area boundary] Site iden- tifier (fig. 5) Station identification number USGS local number Latitude (ddmmss) Longitude (ddmmss) Altitude of land surface, in feet above NGVD of 1929 Site type Well depth, in feet below land surface Date of water- level measure- ment Water level, in feet below land surface Altitude of wate

level, in feet abov

NGVD of 1929 

S1 07056545 Hughes Spring near Zack 355833 924036 620 Spring -- -- -- 620 S2 355317092411601 14N16W04ACB1SP 355317 924116 860 Spring -- -- -- 860 S3 355729092374601 15N16W12ADC1SP 355729 923746 860 Spring -- -- -- 860 S4 355837092375701 15N16W01ABC1SP 355837 923757 900 Spring -- -- -- 900 S5 355837092382301 15N16W01BBD1SP 355837 923823 718 Spring -- -- -- 718 S6 355813092381001 15N16W01CAC1SP 355813 923810 840 Spring -- -- -- 840 S7 355837092384801 15N16W02AAC1SP 355837 923848 790 Spring -- -- -- 790 S8 355840092402701 15N16W03BBD1SP 355840 924027 630 Spring -- -- -- 630 S9 355828092402601 15N16W03BCA1SP 355828 924026 700 Spring -- -- -- 700 

S10 355824092403901 15N16W03BCD1SP 355824 924039 620 Spring -- -- -- 620 S11 355734092395901 15N16W10ACD1SP 355734 923959 680 Spring -- -- -- 680 S12 355724092381601 15N16W12CAB1SP 355724 923816 840 Spring -- -- -- 840 S13 355657092395901 15N16W15ABD1SP 355657 923959 700 Spring -- -- -- 700 S14 355647092395001 15N16W15ADC1SP 355647 923950 700 Spring -- -- -- 700 S15 355441092403301 15N16W27CBD1SP 355441 924033 800 Spring -- -- -- 800 S16 355504092415401 15N16W29ADA1SP 355504 924154 740 Spring -- -- -- 740 S17 355407092445201 15N17W36BCD1SP 355407 924452 897 Spring -- -- -- 897 

W1 355245092355101 14N15W05DCD1 355245 923551 1,110 Well 18 5/09/01 10 1,100 W2 355256092374001 14N15W06CBC1 355256 923740 1,597 Well 35 5/10/01 7 1,590 W3 355827092335201 15N15W03ACB1 355827 923352 1,180 Well 438 1/25/77 258 922 W4 355247092355201 15N15W05DCA1 355247 923552 1,110 Well 70 5/09/01 25 1,085 W5 355717092372301 15N15W07CAC1 355717 923723 1,062 Well 500 6/07/01 213 849 W6 355706092344901 15N15W09DDB1 355706 923449 960 Well 500 5/08/01 141 819 W7 355654092363901 15N15W17BBB1 355654 923639 1,130 Well 500 5/08/01 210 920 
Spring Characterization 19

W8 355629092370901 15N15W18DBB1 355629 923709 1,130 Well 500 5/09/01 128 1,002 W9 355520092371801 15N15W19CDD1 355520 923718 1,100 Well 550 7/09/01 344 756 

W10 355457092345601 15N15W28ACA1 355457 923456 1,180 Well 39 5/10/01 13 1,167 W11 355509092360301 15N15W29ABA1 355509 923603 1,120 Well 200 6/20/01 47 1,073 W12 355358092365401 15N15W31ADD1 355358 923654 1,565 Well 285 6/05/01 88 1,478 W13 355343092351301 15N15W33DBC1 355343 923513 1,105 Well 19 5/09/01 11 1,094 W14 355337092350501 15N15W33DCB1 355337 923505 1,120 Well 300 5/09/01 103 1,017 W15 355820092383801 15N16W02ADD1 355820 923838 1,030 Well 350 6/06/01 283 747 W16 355804092390201 15N16W02DCB1 355804 923902 1,005 Well 140 5/08/01 58 947 W17 355750092413301 15N16W09BBA1 355750 924133 925 Well 950 5/09/01 137 788 W18 355714092404401 15N16W10CCB1 355714 924044 976 Well 300 6/06/01 219 757 W19 355712092395101 15N16W10DDB1 355712 923951 690 Well 35 5/08/01 23 667 W20 355709092393401 15N16W11CCB1 355709 923934 710 Well unknown 6/28/01 39 671 W21 355652092403201 15N16W15BBD1 355652 924032 985 Well 350 5/09/01 76 909 W22 355616092404601 15N16W15CCC1 355616 924046 1,005 Well 355 6/05/01 247 758 W23 355636092394301 15N16W15DAA1 355636 923943 720 Well 70 5/08/01 30 690 W24 355523092433101 15N16W19CDD1 355523 924331 695 Well 17 5/10/01 5 690 W25 355501092395501 15N16W27ADB1 355501 923955 973 Well 6/05/01 87 886 W26 355515092425901 15N16W30AAA1 355515 924259 676 Well 109 7/10/01 27 649 W27 355416092402501 15N16W34BAD1 355416 924025 1,000 Well 485 5/09/01 187 813 W28 355344092382701 15N16W36CCA1 355344 923827 960 Well 115 5/07/01 27 933 W29 355819092445001

15N17W01CBA1 355819 924450 986 Well 1320 7/10/01 240 746

W30* 355719092450301 15N17W11DDA1 355719 924503 960 Well 825 6/26/01 110 850 

W31 355443092444701 15N17W25CAC1 355443 924447 940 Well 300 6/19/01 93 847 W32 355935092391901 16N16W35BAB1 355935 923919 980 Well 550 7/09/01 397 583 

Table 3. Wells and springs inventoried in the Hughes Spring study area--Continued[Geologic unit name refers to the formation from which the spring discharges or the formation at the total depth of the well; USGS, U.S. Geological Survey; ddmmss, 

not located within study area boundary]

Site

identifier

(fig. 5)

Station

identification

number USGS local number

Latitude

(ddmmss)

Longitude

(ddmmss)

Altitude

of land

surface, in

feet above

NGVD

of 1929

Site

type

Well 

depth,

in feet

below

land

surface

Date of

waterlevel

measurement

Water

level, in

feet

below

land

surface

Altitude

of wate

level, in

feet abov

NGVD

of

1929 
20 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 9. Water-level contours of the Hughes Spring study area.

Brush

Creek

Creek

Buffalo

River

Rocky

Creek

Bear

700

947

756

758

813

740

800

700

700

840

680

620

630 790

840

860

718

900

620

819

583

847

746

933

649

886

690

690

909

671

667

757

788

747

920

849

922

1017

1073

1002

900

1000

700

800

600

1100

900

900

800

900

900

800

800

800

700

700

800

800

800

800

1000

900

800

0 1 2 Miles

0 1 2 Kilometers

92°42' 92°36'

36°

35°54'

EXPLANATION

WATER-LEVEL CONTOUR -- Shows altitude at which

water level would have stood in tightly cased wells (2001).

Dashed where approximately located. Hachures indicate

depression. Contour interval 100 feet. Datum is NGVD

OF 1929

GENERALIZED GROUND-WATER FLOW DIRECTION

410 WELL -- Number is water-level altitude,

in feet above NGVD of 1929

435 SPRING -- Number is water-level altitude,

in feet above NGVD of 1929

800

Base from U.S. Geological Survey

digital data, 1:100,000

;

;

;

;

;

;

;

;

;

Hughes

Spring

Recharge Area Characterization

Based on the ground-water tracer test data and 

the spring discharge, it appears that the recharge area 

for Hughes Spring generally coincides with the surface 

drainage area, which is approximately 15.8 mi2. Tracers injected outside the surface drainage area (sites 5-7) 

were not detected at Hughes Spring or other recovery 

sites within the surface drainage area (fig. 10). Tracers 

injected at two sites inside the surface drainage area 

(sites 2 and 3) were detected at Hughes Spring and at 

springs along Brush Creek and in Brush Creek itself, 

indicating a connection between the surface flow in the 

stream and Hughes Spring. The tracer-test data and 

spring-discharge data show that Hughes Spring may act 

like a distributary from Brush Creek during high-flow 

events, discharging a portion of runoff waters resulting 

from precipitation that occurs in the surface drainage 

area. More extensive ground-water tracer tests would 

be needed to further confirm whether the Hughes 

Spring recharge area is coincidental with the surface 

drainage area boundary.

Tracers injected at sites 1 and 4, located inside 

the surface drainage area, and at site 7 outside the surface drainage area, were not recovered at any of the 

monitored springs and wells located in the study area 

(fig. 10; table 4). Because multiple flow paths can exist 

that are not connected in karst areas, the tracers may 

have followed paths that did not coincide with any of 

the monitoring sites. The optical brightener injected at 

site 1 was not successfully recovered during any of the 
Spring Characterization 21Figure 10. Locations of dye injection and recovery sites with implied flow paths of dyes and delineated recharge area for Hughes Spr

Brush

Creek

Creek

Buffalo

River Rocky

Creek

Bear

Sinkhole

7

6

5

3

2

1

4

S1

S9

S8

S6

S5

S4

S3

S2

S15

S16

S14

S13

S11

S10

W28

65

27

65

74

27

74

0 1 2 

0 1 2 Kilometer

Marshall

EXPLANATION

Site types (numberis site identifier)

Recovery sites S1

Recharge area for 1 Injection sites

Hughes Spring

Implied flowpaths

92°42' 92°36'

36°

35°54'

Base from U.S. Geological Surveydigital data, 1:100,000
22 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

tracer tests completed for this entire study and may not 

have been suitable for these hydrologic systems 

because of absorption properties of the tracer or 

because of flow characteristics of the ground-water 

systems.

Tracer tests demonstrated rapid ground-water 

flow velocities in the study area, which are characteristic of conduit-type flow often found in karst systems 

(White, 1988). Using distances measured along 

implied flow paths from injection sites to recovery sites 

(fig. 10), estimated minimum velocities ranged from 

0.04 to 1.30 mi/d (table 4). The highest velocities were 

estimated for tracer tests conducted in January during 

high-flow conditions and for sites with the greatest elevation change. The estimated minimum flow velocities 

ranged from 0.42 to 1.30 mi/d for the January tracer test 

and from 0.04 to 0.27 mi/d for the tracer test conducted 

in May.

Geochemistry

The major ion analyses for five samples collected between September 2001 to October 2002 for 

Hughes Spring (table 5) show a chemistry that is a calcium bicarbonate type (Hem, 1989) and is indicative of 

waters from the Springfield Plateau aquifer (fig. 11). 

The calcium to magnesium ratio ranged from 26 to 38, 

indicating contribution from limestone mineralogy 

(White, 1988). Ratios of calcium to magnesium calculated for other samples collected from wells and 

springs representing the Springfield Plateau aquifer 

indicate ratios ranging from 3 to 70, with a median ratio 

value of 18, also indicating limestone mineralogy. 

Wells and springs representing units in the Ozark aquifer had values for calcium to magnesium ratios ranging 

from 1 to 3 with a median value of 1, indicating a dolomitic mineralogy.

Table 4. Results of ground-water tracer tests in the Hughes Spring study area

[*, Hughes Spring; --, no data]

Injection

site

identifier

(fig. 10)

Injection site

type Tracer injected

Injection

date

Sites where

tracer was

detected

(fig. 10)

Date

tracer was

detected

Number of

days from

injection to

detection

Distance

from

injection

site to

detection

site

(miles)

Apparent

minimum

velocity

(miles per

 day)

1 Sinkhole Optical brightener 1/10/02 None -- -- -- --

2 Swallow hole Eosine OJ 1/10/02 S1* 1/16/02 6 3.7 0.62

S10 1/14/02 4 3.5 0.88

S11 1/14/02 4 2.3 0.58

3 Well Fluorescein 1/11/02 S1* 1/18/02 7 5.4 1.30

S11 1/18/02 7 4.0 0.57

S13 1/18/02 7 3.3 0.47

S14 1/18/02 7 3.1 0.44

Sinkhole 1/16/02 5 2.1 0.42

4 Swallow hole Rhodamine WT 1/11/02 None -- -- -- --

5 Swallow hole Rhodamine WT 5/24/02 S5 5/31/02 7 0.4 0.06

6 Swallow hole Eosine OJ 5/24/02 S1* 8/15/02 83 5.0 0.06

S5 5/31/02 7 1.9 0.27

S11 8/15/02 83 3.6 0.04

7 Swallow hole Fluorescein 5/28/02 None -- -- -- --
Spring Characterization 23

Table 5. Water-quality analyses from samples collected at Hughes Spring, 2001-2002

[ft3/s, cubic foot per second; °C, degrees Celsius; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; e, estimated; μg/L, 

micrograms per liter; <, less than; --, no data]

Constituent Base-flow samples High-flow event samples

Sept. 5, 2001 July 23, 2002 Oct. 15, 2002 Dec. 13, 2001 Mar. 9, 2002

Discharge, ft3/s 1.0 2.1 1.2 12.4 12.6

Water temperature, °C 20 16 16 13 11

Dissolved oxygen, mg/L -- 8.46 7.41 -- 13

Specific conductance, μS/cm 362 397 372 324 180

pH 7.8 7.7 7.8 7.8 7.8

Bicarbonate, dissolved, mg/L 210 224 205 179 106

Calcium, dissolved, mg/L 68.5 82 71.6 63.7 35.8

Magnesium, dissolved, mg/L 1.14 1.45 1.14 1.43 0.82

Sodium, dissolved, mg/L 3.29 3 3.15 2.64 1.37

Potassium, dissolved, mg/L 0.87 0.91 0.80 1.28 0.87

Chloride, dissolved, mg/L 6.3 5.8 5.8 4.6 2.5

Sulfate, dissolved, mg/L 3.85 5.87 3.67 8.98 5.21

Silica, dissolved, mg/L 9.63 9.83 9.46 8.22 6.59

Bromide, dissolved, mg/L 0.056 0.037 0.045 e0.019 <0.030

Fluoride, dissolved, mg/L <0.1 <0.1 <0.1 e0.08 <0.1

Iron, dissolved, μg/L <10 <10 <10 <10 <10

Manganese, dissolved, μg/L <2 <2 e2.93 <2 <2

Total dissolved solids,

calculated, mg/L

197 223 201 184 109

Calcite saturation index 0.47 0.40 0.40 0.29 -0.15

Hardness, mg/L as CaCO3 176 211 180 165 92.8

Ammonia plus organic nitrogen,

 dissolved, mg/L as nitrogen

<0.1 <0.1 <0.1 e0.08 0.11

Nitrite, dissolved, mg/L

as nitrogen

<0.008 <0.008 <0.008 <0.008 <0.008

Nitrite plus nitrate, dissolved,

 mg/L as nitrogen

e0.91 0.97 1.1 1.2 0.79

Phosphorus, dissolved, mg/L e0.02 0.02 0.02 0.02 0.02

Orthophosphorus, dissolved,

 mg/L as phosphorus

e0.01 0.02 e0.01 0.02 0.02

Escherichia coli bacteria,

colonies per 100 milliliters

150 e15 e34 150 680

Fecal coliform bacteria,

colonies per 100 milliliters

e7 e5 68 110 e660

Fecal streptococci bacteria,

colonies per 100 milliliters

e20 70 e58 360 e1,000

Deuterium, ratio per mil -36.5 -- -- -- -36.8

Oxygen-18, ratio per mil -6.18 -- -- -- -6.34

Carbon-13, ratio per mil -13.27 -- -- -- -17.61

Tritium, tritium units 4.1 -- -- -- 2.7

Carbon-14, percent modern

carbon

88.3 -- -- -- 93.66
24 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 11. Relation of ground-water samples from Hughes Spring and other wells and springs in northern Arkansas and 

southern Missouri.

SODIUM PLUS POTASSIUM

CARBONATE PLUS BICARBONATE

SULFATE PLUS CHLORIDE

CALCIUM PLUS MAGNESIUM

CaSO

(gypsum,

anhydrite)

4

CaCO

CaMg(CO )

(calcite,

dolomite)

3

3 2 NaCI

(halite)

NaHCO3

EXPLANATION
Spring Characterization 25

The geochemistry of Hughes Spring is characteristic of a conduit-dominated ground-water flow system. 

Samples were collected at Hughes Spring during baseflow and high-flow conditions and had calcite saturation indices (SIcalcite) values that were noticeably different with different flow conditions. Generally, the 

higher the spring discharge, the less saturated the water 

sample is with respect to calcite, which shows the effect 

of the residence time of the water with the aquifer 

material. Samples collected during base-flow conditions had SIcalcite values near or greater than 0.4 (supersaturated with respect to calcite) while the high-flow 

samples had values of 0.3 and -0.15 (supersaturated to 

undersaturated with respect to calcite). Total dissolved 

solids (TDS) concentrations and hardness also changed 

with flow conditions. Both values decrease as discharge increases, reflecting the effects of reduced residence time of the water with the source rock at higher 

discharge, allowing for less dissolution (table 5). 

Nutrient concentrations at Hughes Spring were 

similar to concentrations in samples collected from 

undeveloped (forest cover greater than or equal to 90 

percent of land use) sites in the Springfield Plateau and 

Ozark aquifers in northern Arkansas and southern Missouri (Adamski, 1997). Nitrite and ammonia concentrations were below detection levels in all of the 

samples. Dissolved phosphorus concentrations were 

approximately 0.02 mg/L, which was mostly in the 

form of orthophosphorus. Nitrite plus nitrate concentrations ranged from 0.79 to 1.2 mg/L as nitrogen, and 

ammonia plus organic nitrogen concentrations were 

approximately 0.1 mg/L as nitrogen (table 5; fig. 12). 

Although the nutrient data did not indicate elevated concentrations caused by surface influences, the 

fecal indicator bacteria demonstrated substantial 

increase in concentration during high-flow conditions. 

During base-flow conditions, concentrations for all of 

the indicator bacteria were below 200 colonies per 100 

milliliters. During high-flow conditions, concentrations for E. coli and fecal coliform ranged from 110 to 

680 colonies per 100 milliliters and fecal streptococci 

ranged from 360 to 1,000 colonies per 100 milliliters. 

The higher concentration during high-flow events indicates that a non-point source of bacteria such as from 

livestock may enter the system from surface-water runoff. One base-flow sample was analyzed for wastewater 

constituents to identify point source contamination; 

however, none of the constituents were above detection 

limits.

Figure 12. Fecal indicator bacteria and nutrient 

concentrations for samples collected from Hughes Spring.

δD and δ18O values were -36.5 and -6.18 per 

mil, respectively, for the base-flow sample and -36.8 

and -6.34 per mil, respectively, for the high-flow sample (table 5). The relation between δD and δ18O of the 

samples are similar to that of the global meteoric line or 

VSMOW standard and generally followed the trend of 

the local meteoric line indicating the samples are representative of direct precipitation entering the aquifer 

system and not influenced by sources of water enriched 

in δ18O through evaporation (fig. 13). 

Stable isotopes of carbon (δ13C; table 5) in 

Hughes Spring indicate that although the ground-water 

system is dominated by conduit flow, a substantial 

component of the source water interacts with surface 

material, such as soils and regolith, before entering the 

ground-water system during high-flow events. Using a 

value of -24 per mil for organically-derived δ13C in the 

ground-water (Clark and Fritz, 1997; P.D. Hays. U.S. 

Geological Survey, oral commun., 2003) and the mea- CONCENTRATION, IN COLONIES PER 100 MILLILITERS

0

200

400

600

800

1000

1200

E. coli

Fecal coliform

Fecal streptococci

Sept. 5, 2001

Dec. 13, 2001

Mar. 9, 2002

July 23, 2002

Oct. 15, 2002

CONCENTRATION, IN MILLIGRAMS PER LITER

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Dissolved ammonia plus organic nitrogen, as nitrogen

Dissolved nitrite plus nitrate, as nitrogen

Dissolved phosphorus, as phosphorus

Concentration less than stated reporting limit

Sept. 5, 2001

Dec. 13, 2001

Mar. 9, 2002

July 23, 2002

Oct. 15, 2002

(Base flow)

(Base flow) (Base flow)

(High flow)

(High flow)

(Base flow)

(Base flow)

(Base flow)

(High flow)

(High flow)

,

,

EXPLANATION

<0.1 <0.1 <0.1 <0.1

<0.1
26 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 13. Relation of deuterium and oxygen-18 isotope ratios in ground-water samples from Hughes Spring and other wells 

and springs in northern Arkansas and southern Missouri.

δ OXYGEN-18, IN PER MIL

-7.5 -7.0 -6.5 -6.0 -5.5 -5.0

δDEUTERIUM, IN PER MIL

-50

-45

-40

-35

-30

-25

Samples of wells and springs

from the U.S. Geological Survey

National Water Information

System database

Hughes Spring samples

δ deuterium = 7.4(δ oxygen-18)+9.4

(LOCAL METEORIC LINE)

METEORIC WATER LINE (VIENNA STANDARD MEAN OCEAN WATER)

Mar. 9, 2002

(High flow)

Sept. 5, 2001

(Base flow)

sured value of -13.27 per mil for the base-flow sample 

collected from Hughes Spring, the proportion of inorganically-derived δ13C was calculated as 45 percent 

and the organically-derived δ13C was calculated as 55 

percent. For the high-flow sample, a measured value of 

-17.61 per mil was used to calculate the proportion of 

inorganically-derived δ13C as 27 percent and the proportion of organically-derived δ13C as 73 percent. An 

enrichment of organically-derived carbon occurs in the 

Hughes Spring discharge during high-flow events from 

water infiltrating into soils in the recharge area before 

entering the aquifer system. The connection of Hughes 

Spring with Brush Creek, shown by the ground-water 

tracer tests, would provide pathways for water enriched 

in organically-derived carbon to reach the spring discharge. During base-flow conditions, water in the 

ground-water system that feeds the Hughes Spring discharge has a longer residence time in the system that 

allows it to approach equilibrium and maintains an even 

distribution of inorganically- and organically-derived 

carbon, caused by buffering (lowering the acidity) from 

carbonate dissolution. Most of the inorganicallyderived carbon in the spring discharge is probably in the 

form of bicarbonate (HCO3) in the ground-water system at the measured pH values, which also shows a substantially lower concentration during high-flow events 

(table 5). 

Radiogenic isotopes (tritium and carbon-14) 

from Hughes Spring indicate that the discharge water is 

a mixture of recent recharge and sub-modern water 

(recharged prior to 1952; tables 2 and 5). The tritium 

values were 4.1 TU for the base-flow sample and 2.7 

TU for the high-flow sample. The lower value for tritium collected at high-flow conditions may reflect the 

higher percentage of recently recharged water in the 

spring discharge. Because carbon-14 is used to date 

older water (50 to 30,000 years), further analysis of the 

data was not conducted.

Stark Spring

Study Area Description

The Stark Spring study area lies in the Springfield Plateau and Salem Plateau physiographic provinces (fig. 1) and is dominated by karstic limestones 

and dolomites of Mississippian to Ordovician age. The 

altitude of the study area ranges from 268 to 726 ft 
Spring Characterization 27

above NGVD of 1929. Land use in the area consists 

primarily of deciduous and evergreen forest (91 percent) and some pasture (9 percent). No urban areas are 

located in the study area (Vogelmann and others, 2001).

Annual mean temperatures recorded at Batesville (fig. 1) in calendar years 2001 and 2002 were

18 °C and 17 °C, respectively, which were near normal 

based on a 54-year period from 1932 to 1995 (Hoare, 

1996). The annual rainfall recorded at Batesville was 

36 inches for 2001and 55 inches for 2002 (National 

Oceanic and Atmospheric Administration, 2001; 

2002). The average annual rainfall for Batesville is 52 

inches (Hoare, 1996). 

Hydrogeology

The Mississippian-age Boone Formation (fig. 3) 

is exposed throughout most of the study area at high 

altitudes with some small occurrences of the Moorefield Formation (fig. 14). Silurian- and Devonian-age 

units are present in the northern and western portions of 

the study area, but are absent in the area near Stark 

Spring, resulting in an unconformable contact of the 

Boone Formation and the Ordovician-age Cason Shale 

and Joachim Dolomite units (fig. 3).

Field observations in the area indicate that where 

the Boone Formation is exposed, surface runoff only 

occurs during periods of intense rainfall. Stark Spring 

occurs at the contact of the Boone Formation and the 

underlying less permeable and less karstic Cason Shale 

(fig. 15). Mill Spring (fig. 14) also appears to be a contact spring that discharges water from the Boone Formation in the study area.

Discharge, Temperature, and Precipitation

The discharge for Stark Spring varied seasonally 

and temporally with precipitation (fig. 16). The mean 

annual discharge for water years 2001 and 2002 were 

0.5 and 1.5 ft3/s, respectively (Brossett and Evans, 

2003). Mean daily discharge ranged from approximately 0.1 to 23 ft3

/s for water year 2001 and from 0.1 

to 49 ft3/s for water year 2002. The spring discharge 

generally followed precipitation patterns with the highest mean daily discharges in the months of January 

through May and the lowest daily discharges generally 

in the months of July through November.

Water temperature recorded at Stark Spring had 

little seasonal variation for water years 2001 and 2002, 

although noticeable temperature fluctuations occurred 

during high-flow events. Recorded water temperature 

ranged from 13.5 °C to 14.7 °C with a mean of 14.5 °C 

(fig. 16). Unlike Hughes Spring, noticeable temperature fluctuations caused by high-flow events occurred 

mostly in the fall and winter months (figs. 16 and 17).

On average, the base flow accounted for approximately 40 percent of the discharge volume for the 

period of October 2000 through September 2002. Discharge exceeded the base condition by more than 5 percent during 55 percent of the monitoring period. The 

ratio of peak-flow to base-flow discharge (491) for 

Stark Spring (based on the entire period of record), 

indicates a fast-response spring (White, 1988).

Recharge Area Characterization

The recharge area computed from the recorded 

discharge indicated that the area approximated by the 

surface drainage was not large enough to produce the 

discharge observed at Stark Spring. The computed 

recharge area ranged from 0.39 to 0.86 mi2

 using a 

water-balance calculation of the discharge during five 

storms and assuming 100 percent of the rainfall entered 

the ground-water system (fig. 18; table 6). The surface 

drainage area was approximately 0.34 mi2

. Assuming a 

10 percent reduction in the recharge volume from 

evapotranspiration, soil absorption, and vegetation 

interception, the computed recharge area ranged from 

0.43 to 0.96 mi2 (fig. 18; table 6). The January 22, 

2002, storm resulted in the smallest computed recharge 

area (table 6) and may be attributed to how the rainfall 

was distributed across the recharge area during the 

event. An average computed recharge area of 0.79 mi2 

from the five storms, assuming a 10 percent reduction 

in recharge volume was used with ground-water tracer 

test data to delineate the recharge area for Stark Spring.

The configuration of the recharge area for Stark 

Spring was found to be considerably different than the 

surface drainage from tracer-test data and geologic 

characteristics of the area. The recharge area is controlled predominantly by the occurrence of the Boone 

Formation outcrop. No major structural features were 

observed from geologic mapping or field observations 

near the spring, and tracer-test results show that the 

recharge area extends outside the surface drainage area 

to the west of the spring surface drainage area (fig. 19). 
28 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 14. Geology of the Stark Spring study area.

Poke

Bayou

Cave 

Spring Creek

Mbn

Mbn

Ose

Ose

Ocj

Ocj

Ocj

Mm

Slsb

Slsb

MDcp

MDcp

Stark

Spring

69

0 0.5 

0 0.5 

Cave

Spring

Mill

Spring

EXPLANATION

35°49'12"

91°42'36" 91°39'

35°51'

Mm

Mbn

MDcp

Moorefield FormationBoone FormationChattanooga Shale, Clifty Limestone, and Penters ChertLafferty Limestone, St. Claire Limestone,and Brassfield Limestone MemberCason Shale, Joachim DolomiteSt. Peter Sandstone and Everton Formation

Slsb

Ocj

Ose

SinkholeCave

Fault - Bar and ball on downthrown sideSpring

Geology modified from E.E. GlickU.S. Geological Survey, unpub data., 1973Base from U.S. Geological Surveydigital data, 1:100,000
Spring Characterization 29Figure 15. Conceptual model of ground-water flow to Stark Spring.

Stark

Spring

LARGE

CONDUITS

BOONE FORMATION

JOACHIM DOLOMITE

ST. PETER SANDSTONE

EVERTON FORMATION

WEST 

SINKHOLE

ENLARGEDFRACTURES ;

;

; ;

; ;

; ;

; ;

;

;

;

; ;

;

EXPLANATIONGeneralized ground-wa

flow direction
30 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 16. Daily discharge, rainfall, and water temperature recorded at Stark Spring. DISCHARGE, IN CUBIC FEET PER SECOND

0.01

0.1

1

10

100

RAINFALL, IN INCHES

0

1

2

3

4

5

6

DATE

TEMPERATURE, IN 

DEGREES CELSIUS

8

10

12

14

16

18

20

22

24

WATER YEAR 2001 WATER YEAR 2002

Nov Jan Mar May July Sept Nov Jan Mar May July Sept 

Nov Jan Mar May July Sept Nov Jan Mar May July Sept 

Nov Jan Mar May July Sept Nov Jan Mar May July Sept 

Water-quality

sample collected

October 17, 2002

TOTAL

MEASURED

WATER-QUALITY SAMPLE

BASEFLOW
Spring Characterization 31

Figure 17. Discharge and water temperature data from Stark Spring for three storms.

Figure 18. Runoff discharge for selected storms from Stark Spring.

2/12/01 2/16/01 2/20/01 2/24/01 2/28/01 3/4/01 3/8/01

DISCHARGE, IN CUBIC FEET PER SECOND

0

5

10

15

20

25

30

TEMPERATURE, IN DEGREES CELSIUS

14.0

14.2

14.4

14.6

14.8

15.0

DISCHARGE

TEMPERATURE

1/25/02 1/29/02 2/2/02 2/6/02

DISCHARGE, IN CUBIC FEET PER SECOND

0

5

10

15

20

25

30

TEMPERATURE, IN DEGREES CELSIUS

14.2

14.3

14.4

14.5

14.6

14.7

14.8

DISCHARGE

TEMPERATURE

DATE

3/5/02 3/9/02 3/13/02 3/17/02 3/21/02 3/25/02 3/29/02

DISCHARGE, IN CUBIC FEET PER SECOND

0

5

10

15

20

25

30

TEMPERATURE, IN DEGREES CELSIUS

13.0

13.5

14.0

14.5

15.0

DISCHARGE

TEMPERATURE
32 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 19. Locations of dye injection and recovery sites with implied flow path and the estimated local recharge area for Stark Spring

Spring

Creek

Poke

Bayou

Cave

StarkSpring

CaveSpring

MillSpring

3

2

4

1

0 

0 

91°42' 91°39

35°51'35°49'

69

EXPLANATION

Site types (with site identifier)

Injection sites

Recovery sites

1

StarkSpring Implied flowpath

Surface drainage area

Estimated recharge area

Base from U.S. Geological Surveydigital data, 1:100,000
Spring Characterization 33

Table 6. Storm events and calculated recharge areas for Stark Spring

Storm

Total

storm runoff

volume

(cubic feet)

Total

storm

precipitation

(inches)

Storm

intensity

(inches

per day)

Calculated

recharge

area

assuming

all rainfall

is recharge

(square

 miles)

Calculated

recharge area

assuming

10 percent

loss of 

recharge

(square

 miles)

Feb. 13, 2001 5,241,000 3.5 1.3 0.65 0.72

Jan. 22, 2002 1,713,000 1.9 1.1 0.39 0.43

Jan. 30, 2002 4,001,000 2.0 1.5 0.86 0.96

Mar. 18, 2002 5,472,000 2.8 2.2 0.84 0.93

Mar. 24, 2002 3,402,000 1.8 1.8 0.81 0.90

Average 0.71 0.79

Only one tracer was recovered in the study area. The 

tracer was injected into a sinkhole (site 1) in the Boone 

Formation located outside the surface drainage area 

and detected at Stark Spring (fig. 19; table 7). Although 

the tracer at site 2 was not detected at Stark Spring, it 

was considered to have originated within the recharge 

area based on the recharge area size estimated from the 

discharge data and extent of the Boone Formation. The 

negative detection of the tracer was probably caused by 

a large amount of organic debris in the sinkhole that 

may have absorbed enough of the tracer to prevent a 

detectable amount to enter the ground-water system. 

The recharge area boundary is very approximate, as the 

area may have a different configuration depending on 

the flow conditions. More extensive ground-water 

tracer tests would be needed to further confirm the 

location of the Stark recharge area boundary at different flow conditions.

Tracer tests demonstrated rapid ground-water 

flow velocities in the study area, which are characteristic of conduit-type flow often found in karst systems 

(White, 1988). A velocity of 0.06 mi/d was estimated 

from the tracer test using a distance measured along an 

implied flow path from injection site 1 to Stark Spring 

(fig. 19; table 7). Velocities are likely to be affected by 

the flow conditions and slope as was observed at 

Hughes Spring (table 4).

Geochemistry

The major ion analyses for six water samples 

collected between September 2001 and November 

2002 from Stark Spring reflect a chemistry similar to 

Hughes Spring, and typical of waters from the Springfield Plateau aquifer (Boone Formation) (table 8; fig. 

20). All samples collected from Stark Spring regardless 

of the flow condition had calculated calcium to magnesium ratio values of 9 or 10, indicating contribution 

from a limestone mineralogy (White, 1988) similar to 

other sample data representative of the Springfield Plateau aquifer found in the USGS NWIS database.

Samples collected at Stark Spring had SIcalcite

values that were considerably different with different 

flow conditions. Generally, the higher the discharge, 

the less saturated the water sample was with respect to 

calcite, which shows the effect of the residence time 

with the aquifer material. Samples taken during baseflow conditions had SIcalcite values ranging from -0.12 

to 0.16 while high-flow samples had values ranging 

from -1.05 to 0.34. The two samples collected on February 20 and March 19, 2002, had discharges of 5.5 and 

25 ft3/s, respectively, and SIcalcite values of -0.4 and

-1.05 ft3/s, respectively. The other samples were collected at discharges less than or equal to 0.5 ft3

/s and 

had SIcalcite values ranging from -0.12 to 0.34. The discharge for the high-flow event sampled on November 

29, 2001, although about twice as large as for base-flow 

samples, was substantially less than that for the other 

two high-flow event samples.
34 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 20. Relation of ground-water samples from Stark Spring and other wells and springs in northern Arkansas and southern 

Missouri.

SODIUM PLUS POTASSIUM

CARBONATE PLUS BICARBONATE

SULFATE PLUS CHLORIDE

CALCIUM PLUS MAGNESIUM

CaSO

(gypsum,

anhydrite)

4

CaCO

CaMg(CO )

(calcite,

dolomite)

3

3 2 NaCI

(halite)

NaHCO3

EXPLANATION
Spring Characterization 35

Table 7. Results of ground-water tracer tests in the Stark Spring study area

[--, no data]

Injection

site

identifier

Injection

site type Tracer injected

Injection

date

Sites where

tracer was

detected

Dates

tracer was

first

detected

Number of

days from

injection to

detection

Distance

from

injection

site to

detection

site

(miles)

Apparent

minimum

velocity

(miles

per day)

1 Sinkhole Eosine OJ 4/23/02 Stark 5/11/02 19 1.1 0.06

2 Sinkhole Fluorescein 4/23/02 None -- -- -- --

3 Sinkhole Optical brightener 4/24/02 None -- -- -- --

4 Well Rhodamine WT 4/24/02 None -- -- -- --

Total dissolved solids (TDS) and hardness also 

demonstrated noticeable differences depending on the 

discharge. Both values decreased as discharge 

increased, reflecting the effects of reduced residence 

time of the water with the source rock at higher discharge, allowing for less dissolution (table 8).

Unlike major ion concentrations, nutrient concentrations for Stark Spring did not vary with different 

flow conditions (fig. 21). Dissolved nitrite plus nitrate 

concentrations ranged from 0.29 mg/L to 0.74 mg/L as 

nitrogen. Adamski (1997) presented nitrite plus nitrate 

concentrations of 0.98 mg/L as nitrogen for the 90th 

percentile of samples collected from 25 undeveloped 

sites (forest cover greater than 90 percent) in areas 

overlying the Springfield Plateau and Ozark aquifers. 

Dissolved phosphorus and orthophosphorus concentrations for Stark Spring ranged from 0.03 to 0.06

mg/L. These concentrations were higher than the 90th 

percentile concentrations for undeveloped sites (0.02 

mg/L for phosphorus and 0.01mg/L for orthophosphorus; Adamski, 1997).

Concentrations of fecal indicator bacteria in 

samples collected at Stark Spring generally were 

higher in samples collected during base-flow conditions than in samples collected during high-flow conditions (fig. 21). Lower concentrations during high-flow 

conditions may be caused by dilution effects from the 

large inflow of runoff water and attributed to the land 

use in the recharge area. Petersen and others (1999) 

noted higher concentrations of bacteria in areas with 

predominately agricultural land use. The land use of 

the Stark Spring area is only 9 percent pasture, while 

the area near Hughes Spring, which had higher concentrations of bacteria at high flows, is composed of 38 

percent pasture, a possible source of bacteria. 

Stable isotopes (δD and δ18O) for Stark Spring 

generally followed the trend of the local meteoric line 

and were similar to that of the global meteoric line 

(VSMOW) indicating that they are representative of 

direct precipitation entering the aquifer system and not 

influenced by sources of water enriched in δ18O 

through evaporation (fig. 22). Values for δD and δ18O 

were -36.7 and -6.22 per mil, respectively, for the baseflow sample and -37.9 and -6.29 per mil, respectively, 

for the high-flow sample. 

δ13C data show that the recharge water for Stark 

Spring has less interaction with the soil and regolith 

before entering the ground-water system than observed 

at Hughes Spring. The high-flow sample collected 

from Stark Spring had a δ13C value of -12.13 per mil, 

yielding an estimated 39 percent inorganically-derived 

δ13C and 61 percent organically-derived δ13C. The 

base-flow sample collected from Stark Spring had a 

δ13C of -14.62 per mil indicating an even distribution 

of 50 percent organically- and inorganically-derived 

δ13C. Unlike Hughes Spring, where the percentages of 

organically-derived carbon increased during high flow, 

Stark Spring displayed a decrease in the calculated percentage of organically-derived carbon during high-flow 

conditions. These data indicate that runoff enters the 

ground-water system at a more rapid rate near Stark 

Spring than near Hughes Spring, and does not allow 

sufficient interaction with surface material in the 

recharge area for the transport of organically-derived 

carbon into the ground-water system. 
36 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Table 8. Water-quality analyses from samples collected at Stark Spring, 2001-2002

[ft3/s, cubic foot per second; °C, degrees Celsius; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; μg/L, micrograms 

per liter; <, less than; e, estimated; --, no data]

Constituent Base-flow samples High-flow event samples

Sept. 5, 2001 July 23, 2002 Oct. 15, 2002 Nov. 29, 2001 Feb. 20, 2002 Mar. 19, 2002

Discharge, ft3/s 0.21 0.27 0.23 0.5 5.5 25

Water temperature, °C 17 15 15 14 14 14

Dissolved oxygen, mg/L -- 10.1 7.6 10 11.4 12.6

Specific conductance, μS/cm 256 261 269 255 161 109

pH 7.8 7.9 7.6 8.1 7.8 7.5

Bicarbonate, dissolved, mg/L 149 135 144 144 80.5 48.8

Calcium, dissolved, mg/L 43.3 47.4 48.0 44.9 27.1 17.8

Magnesium, dissolved, mg/L 2.86 2.91 2.99 2.95 1.72 1.12

Sodium, dissolved, mg/L 2.52 2.43 2.52 2.39 1.65 1.32

Potassium, dissolved, mg/L 0.98 0.89 0.89 0.84 0.97 0.90

Chloride, dissolved, mg/L 5.80 6.01 5.54 5.80 4.12 1.91

Sulfate, dissolved, mg/L 4.34 4.51 4.69 3.94 6.25 5.81

Silica, dissolved, mg/L 9.30 9.91 9.83 9.33 9.23 9.25

Bromide, dissolved, mg/L 0.061 0.040 0.045 0.047 0.019 <0.030

Fluoride, dissolved, mg/L <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

Iron, dissolved, μg/L <10 <10 <10 <10 <10 <10

Manganese, dissolved, μg/L <2 <2 e2.17 <2 <2 e0.95

Total dissolved solids,

calculated, mg/L

142 143 149 144 93 62

Calcite saturation index 0.08 0.16 -0.12 0.34 -0.4 -1.05

Hardness, mg/L as CaCO3 120 130 130 124 75 49

Ammonia plus organic nitrogen

 dissolved, mg/L as nitrogen

<0.1 <0.1 <0.1 <0.1 <0.1 e0.07

Nitrite, dissolved, mg/L as

nitrogen

<0.008 <0.008 <0.008 <0.008 <0.008 <0.008

Nitrite plus nitrate, dissolved,

 mg/L as nitrogen

e0.56 0.59 0.74 0.59 0.53 0.29

Phosphorus, dissolved, mg/L e0.05 0.05 0.05 0.06 0.04 0.03

Orthophosphorus, dissolved,

 mg/L as phosphorus

e0.04 0.06 0.04 0.05 0.03 0.03

Escherichia coli bacteria,

colonies per 100 milliliters

15 <3 e20 <3 e20 e20

Fecal coliform bacteria,

colonies per 100 milliliters

230 <3 e28 <3 e7 <3

Fecal streptococci bacteria,

colonies per 100 milliliters

57 e18 e18 <3 <3 e15

Deuterium, ratio per mil -36.7 -- -- -- -37.9 --

Oxygen-18, ratio per mil -6.22 -- -- -- -6.29 --

Carbon-13, ratio per mil -14.62 -- -- -- -12.13 --

Tritium, tritium units 3.5 -- -- -- 3.2 --

Carbon-14, percent modern

carbon

103.6 -- -- -- 87.8 --
Spring Characterization 37

Figure 21. Fecal indicator bacteria and nutrient concentrations for samples collected at Stark Spring.

Figure 22. Relation of deuterium and oxygen-18 isotope ratios in ground-water samples from Stark Spring and other wells and 

springs in northern Arkansas and southern Missouri. CONCENTRATION, IN COLONIES PER 100 MILLILITERS

0

50

100

150

200

250

300

E. coli

Fecal coliform

Fecal streptococci

CONCENTRATION, IN MILLIGRAMS PER LITER

0.0

0.2

0.4

0.6

0.8

1.0

Nitrite plus nitrate as nitrogen

Ammonia plus organic nitrogen, as nitrogen

Sept. 5, 2001 Nov. 29, 2001

Mar. 19, 2002

July 23, 2002

Oct. 15, 2002

Feb. 20, 2002

Sept. 5, 2001

Nov. 29, 2001 Mar. 19, 2002 July 23, 2002

Feb. 20, 2002 Oct. 15, 2002

(Base flow)

(Base flow)

(Base flow)

(High flow) (High flow)

(High flow)

(Base flow) (Base flow)

(Base flow)

(High flow) (High flow)

(High flow)

<0.1 <0.1 <0.1 <0.1 <0.1

<0.1 Concentration less than stated reporting limit

<0.1

<3

<3

<3

<3 Concentration less than

stated reporting limit

-7.5 -7.0 -6.5 -6.0 -5.5 -5.0

-50

-45

-40

-35

-30

-25

Samples of wells and spring

from USGS NWIS database

Stark Spring samples

δ deuterium = 7.4(δ oxygen-18)+9.4

METEORIC WATER LINE (VIENNA STANDARD MEAN OCEAN WATER)

Feb. 2, 2002

Sept. 5, 2001

(Base flow)

(High flow)

δ OXYGEN-18, IN PER MIL

δ DEUTERIUM, IN PER MIL

(LOCAL METEORIC LINE)
38 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Radiogenic isotopes (tritium and carbon-14) 

from Stark Spring indicated that the discharge water is 

a mixture of recent recharge and sub-modern water 

(recharged prior to 1952; tables 2 and 8). The tritium 

values were 3.5 TU for the base-flow sample and 3.2 

TU for the high-flow sample. Because carbon-14 is 

used to date older water (50 to 30,000 years), further 

analysis of the data was not conducted.

Evening Shade

Study Area Description

The Evening Shade Spring study area lies in the 

Salem Plateau physiographic province (fig. 1). The altitude of the study area ranges from 303 to 805 ft above 

NGVD of 1929. Land use in the area consists primarily 

of deciduous and evergreen forest land (74 percent) and 

agricultural land (25 percent). Urban land use consists 

of less than 1 percent of the study area (Vogelmann and 

others, 2001).

Annual mean temperatures recorded at Evening 

Shade (fig. 23) for calendar years 2001 and 2002 were 

16 °C and 15 °C, respectively, which were near normal 

based on a 34-year period from 1939 to 1995 (Hoare, 

1996). The annual rainfall recorded at Evening Shade 

was 48 inches for 2001 and 61 inches for 2002 

(National Oceanic and Atmospheric Administration, 

2001; 2002). The average annual rainfall for Evening 

Shade is 44 inches (Hoare, 1996).

Hydrogeology

The predominant surficial bedrock units exposed 

in the Evening Shade study area include Ordovicianaged limestone, dolomite, and sandstone formations 

that compose the Ozark aquifer. These formations 

include (from youngest to oldest) the St. Peter Sandstone, Everton Formation, Powell Dolomite, and Cotter 

Dolomite (figs. 3 and 23). Other important formations 

that are not exposed but occur in the subsurface include 

the Jefferson City Dolomite, Roubidoux Formation, 

and Gasconade Dolomite. The units generally have a 

slight dip to the south-southeast with an angle of less 

than 1 degree estimated from geophysical logs. No 

major structural features were evident in the study area 

from field observations and geophysical logs. Few vertical fractures were observed in geophysical logs, but 

horizontal bedding planes were observed and likely 

provide the preferred pathways for dissolution.

The St. Peter Sandstone unconformably overlies 

the Everton Formation. These units are not differentiated from each other in the study area. Thickness of the 

two units ranged from 0 to 488 ft from geophysical logs 

of wells in the study area (fig. 24), although thicknesses 

of as much as 1,380 ft have been reported in other areas 

of northern Arkansas (Caplan, 1957) (fig. 3). The outcrop of the St. Peter Sandstone/Everton Formation covers most of the study area south of the Strawberry River 

(fig. 23). Several karst features such as sinkholes and a 

cave were observed on the outcrop of the St. Peter 

Sandstone/Everton Formation. 

The Powell Dolomite is exposed across the 

northern portion of the study area (fig. 23). The range 

of thickness has been reported from 0 to 420 ft in northern Arkansas (Caplan, 1960) and was observed to be at 

least 107 ft thick in the study area from geophysical 

logs. The Cotter and Jefferson City Dolomites generally are undifferentiated in the subsurface. The range of 

thickness of the Cotter Dolomite has been reported 

from 0 to 527 ft and the Jefferson City dolomite had a 

reported thickness ranging from 100 to 496 ft (Caplan, 

1957; 1960; McFarland, 1998) (fig. 3).

The Roubidoux Formation unconformably overlies the Gasconade Dolomite and ranges in thickness 

from 130 to 455 ft and is exposed across a large area in 

southeastern Missouri (Caplan, 1957; 1960) (fig. 3). 

The Gasconade Dolomite is mainly composed of 

cherty dolostone, but contains a sandstone unit in its 

lowermost part designated as the Gunter Sandstone 

Member. The thickness of the Gasconade ranges from 

300 to 600 ft (fig. 3). 

Evening Shade Spring discharges through two 

main discharge points in the Everton Formation outcrop. One has been enclosed by a springhouse for utilization as a public- water supply for the city of Evening 

Shade and the surrounding area. The other resurgent 

point is in the stream channel of Mill Creek near the 

springhouse. The location of Evening Shade Spring 

may be caused by a set of enlarged vertical fractures or 

conduits not readily visible at the surface that may concentrate and convey flow to the surface from fractures 

and conduits in multiple formations composing the 

Ozark aquifer (fig. 25).
Spring Characterization 39

Figure 23. Geology of the Evening Shade Spring study area.

Piney

Fork

Strawberry

River

Mill

Whaley

Creek

Bird

Creek

Dry

Branch

Cr eek

Ose

Ose

Ose

Opw

Opw

Oc

Oc

Ose

Mbn

K

Tg

Evening

Shade

Spring

58

56

Evening Shade

Sidney

0 1 2 Miles

0 1 2 Kilometers

167

167

Izard Co.

Sharp Co.

36°

91°40' 91°30'

36°05'

Tg

K

Mbn

Ose

Opw

Oc

EXPLANATION

Tertiary units

Cretaceous units

Boone Formation

St. Peter Sandstone

and Everton Formation

Powell Dolomite

Cotter Dolomite

Cave

Sinkhole

Spring

Geology modified from E.E. Glick

U.S. Geological Survey, unpub data., 1973

Base from U.S. Geological Survey

digital data, 1:100,000
40 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 24. Distribution of wells and springs in the Evening Shade Spring study area.

Strawberry

River

Piney

Whaley

Creek

Bird Creek

Mill Creek

Dry

Branch

167

167

56

58

Izard Co.

Sharp Co.

Sidney

Evening Shade Fork

S11

W8

W7

W9

W6

W5

W4

W3

W2 W1

W51

W50

W49

W48

W46 W47

W45

W44

W43

W42

W41

W40

W39

W38

W36 W37

W35

W34

W32 W33

W31

W30

W29

W28

W27 W26

W25

W22 W23 W24

W21

W20

W19

W18

W17

W16

W15

W14

W13

W12

W11 W10

S9

S8

S7

S6

S5

S4

S3

S2

S1

S18

S17

S16

S15

S14

S13

S12

S10

0 1 2 Miles

0 1 2 Kilometers

36°

36°05'

91°40' 91°30'

Evening

Shade

Spring

Base from U.S. Geological Survey

digital data, 1:100,000

EXPLANATION

Wells by contributing

geologic unit

(Identifier refers to

table 9)

Unknown

Everton Formation

Powell Dolomite

Cotter Dolomite

Roubidoux Formation

Gunter Sandstone Member

of the Gasconade Dolomite

Wells used for geophysical

survey

Wells sampled for water

quality

Springs

Spring sampled for water

quality
Spring Characterization 41

Discharge, Temperature, and Precipitation

The discharge for Evening Shade Spring 

remained fairly constant with time. The mean daily discharge computed from the springhouse ranged from 

0.88 to 2.29 ft3/s for water year 2001 and from 0.76 to 

2.25 ft3

/s for water year 2002. The mean annual discharge for water years 2001 and 2002 was 1.44 and 

1.24 ft3/s, respectively (Brossett and Evans, 2003) (fig. 

26). The mean annual discharge for 2001 may be 

underestimated because of missing data during the 

period of December 2000 and January 2001. The 

spring discharge periodically measured in the channel 

of Mill Creek ranged from 3.6 to 9.0 ft3/s during water 

years 2001 and 2002 (fig. 26). 

On average, the base-flow discharge for Evening 

Shade Spring accounted for approximately 95 percent 

of the total discharge volume for the monitoring period. 

The largest base-flow component occurred during the 

period of June through September for both water years 

2001 and 2002 (fig. 26). Small peaks were evident during periods of intense rainfall that indicated a small 

component of local recharge. The local recharge may 

occur immediately adjacent to the spring as infiltration 

through the shallow subsurface, but not at substantial 

volumes (<5 percent of flow on average). Discharge 

exceeded base flow by more than 5 percent during less 

than 40 percent of the monitoring period. The ratio of 

base flow to peak flow for Evening Shade Spring 

ranged from 2.6 to 3.0 indicating a slow-response 

spring (White, 1988). The discharge for Evening Shade 

Spring contrasts with the fast response, storm input 

type of discharge that was observed at Hughes and 

Stark Springs. 

Water temperature recorded at Evening Shade 

Spring remained fairly constant with time. The 

recorded temperature ranged from 16.7 to 16.8 °C 

from February 2001 to July 2002 (fig. 26). The relatively stable discharge and temperature suggest that the 

Evening Shade Spring discharge probably is representative of a regional ground-water system.

Water-Level Contours

Water-level contours constructed from static 

water levels measured in 51 wells and 18 springs in calendar year 2001 (table 9) generally follow land surface 

topography in the area and indicate that ground water 

flows toward the Strawberry River and the Piney Fork 

in the northern portion of the study area (fig. 27). The 

contours follow a similar pattern to the regional flow of 

the Ozark aquifer constructed by Pugh (1998) and 

Schrader (2001). An area of higher water-level altitude 

was evident in the central portion of the study area 

between the Piney Fork and Strawberry River in an area 

referred to as “The Backbone.” This mounding of the 

water level may be caused by a restriction or isolation 

of the water table from the surrounding system by a 

layer of low permeability limestone or shale observed 

in geophysical logs (figs. 25 and 27).

Recharge Area Characterization

The discharge, geochemical, and hydrogeologic 

data indicate that the discharge for Evening Shade 

Spring is mostly representative of a regional groundwater flow system (Ozark aquifer) and does not allow 

for a distinct boundary to be delineated for the recharge 

area contributing to the spring. Ground-water tracer 

tests conducted in the study area to identify a connection between Evening Shade Spring and local groundwater flow systems resulted in the negative recovery of 

the three tracers injected into two wells and a sinkhole 

(fig. 24). Although the tracer tests did not establish that 

a local recharge area does not exist conclusively, they 

lend support that the Evening Shade Spring is mainly 

recharged from the Ozark aquifer. The recharge area 

could include relatively remote locations where hydrogeologic units composing the Ozark aquifer are 

exposed and have sufficient porosity and hydraulic 

conductivity to convey water that falls as precipitation 

to the subsurface. 

Geochemistry

The major ion analyses from Evening Shade 

Spring (table 10) and from wells and springs in the 

study area (table 11) demonstrate a calcium bicarbonate type water typical of the Ozark aquifer (fig. 28). All 

samples collected from Evening Shade Spring had calcium to magnesium ratio values of 1.3, indicating contribution from a dolomitic mineralogy (White, 1988) 

that also is representative of formations of the Ozark 

aquifer. The ratios of the other wells and spring had 

similar values ranging from 0.8 to 1.2. 
42 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 25. Conceptual model of ground-water flow to Evening Shade Spring.

Strawberry

River

Piney

Fork

Mill

Creek

Evening Shade

Spring

NORTH 

ST. PETER SANDSTONE

EVERTON FORMATION

POWELL DOLOMITE

COTTER DOLOMITE

JEFFERSON CITY DOLOMITE

ROUBIDOUX FORMATION

ZONE OF LOW

PERMEABILITY ENLARGED

BEDDING

PLANE

;

;

;

;

;

;

;

;

;

;

;

;

;

;

;

;

;

;

;

;

;

;

EXPLANATIONGeneralized flow

; direction
Spring Characterization 43

Figure 26. Daily discharge, rainfall, and water temperature recorded at Evening Shade Spring. DISCHARGE, IN CUBIC FEET PER SECOND

0.01

0.1

1

10

100

RAINFALL, IN INCHES

0

1

2

3

4

DATE

TEMPERATURE, IN 

DEGREES CELSIUS

8

10

12

14

16

18

20

22

24

WATER YEAR 2001 WATER YEAR 2002

Oct Dec Feb Apr June Aug Oct Dec Feb Apr June Aug 

Oct Dec Feb Apr June Aug Oct Dec Feb Apr June Aug 

Oct Dec Feb Apr June Aug Oct Dec Feb Apr June Aug 

Water-quality

sample collected

October 16, 2002

Discharge Recorded from Springhouse

Spring Discharge Measured in Mill Creek

Spring Discharge Measured From Springhouse

Water-Quality Sample From Springhouse

Baseflow Springhouse Discharge
44 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas Table 9. Wells and springs inventoried in the Evening Shade Spring study area [Geologic formation refers to the formation from which the spring discharges or the formation at the total depth of the well; USGS, U.S. Geological Survey; ddmmss

Site identi-fier (fig. 24) Station identification number USGS local number Latitude (ddmmss) Longitude (ddmmss) Altitude of land surface, in feet above NGVD of 1929 Site type Well depth, in feet below land surface Date of water- level measure- ment Water level, in feet below land surface Altitud

of wate

level, 

feet abo

NGVD of 1929 

S1 07073595 Evening Shade Spring near Evening Shade 360325 913631 435 Spring -- -- -- 435 S2 360228091321101 16N05W17AAB1SP 360228 913211 495 Spring -- -- -- 495 S3 360215091321501 16N05W17ADB1SP 360215 913215 550 Spring -- -- -- 550 S4 360103091310801 16N05W21DAA1SP 360103 913108 485 Spring -- -- -- 485 S5 360353091352801 16N06W02ADC1SP 360353 913528 455 Spring -- -- -- 455 S6 360419091370801 16N06W03BAB1SP 360419 913708 460 Spring -- -- -- 460 S7 360355091373501 16N06W04ADC1SP 360355 913735 500 Spring -- -- -- 500 S8 360241091383501 16N06W09CCC1SP 360241 913835 545 Spring -- -- -- 545 S9 360325091364801 16N06W10ABB1SP 360325 913648 455 Spring -- -- -- 455 

S10 355959091361401 16N06W26CBA1SP 355959 913614 660 Spring -- -- -- 660 S11 360821091382801 17N06W08DAA1SP 360821 913828 680 Spring -- -- -- 680 S12 360804091375101 17N06W09CDC1SP 360804 913751 538 Spring -- -- -- 538 S13 360815091374801 17N06W09DBC1SP 360815 913748 557 Spring -- -- -- 557 S14 360624091384601 17N06W20DCA1SP 360624 913846 457 Spring -- -- -- 457 S15 360523091344801 17N06W25CDA1SP 360523 913448 460 Spring -- -- -- 460 S16 360602091371901 17N06W27BBC1SP 360602 913719 460 Spring -- -- -- 460 S17 360633091343401 17N06W24DBB1SP 360633 913434 405 Spring -- -- -- 405 
Spring Characterization 45

S18 360456091353301 17N06W35ACA1SP 360456 913533 490 Spring -- -- -- 490 

W1 360349091322401 16N05W05DBA1 360349 913224 440 Well unknown 6/5/01 83 357 W2 360350091332401 16N05W06ACD1 360350 913324 400 Well 110 6/7/01 32 368 W3 360233091333801 16N05W06DCC1 360233 913338 450 Well 1110 3/30/01 42 408 W4 360312091331101 16N05W07AAD1 360312 913311 435 Well 300 3/29/01 34 401 W5 360148091345201 16N05W13CDD1 360148 913452 660 Well 225 3/20/01 158 502 W6 360135091310401 16N05W16DDD1 360135 913104 625 Well 240 3/29/01 170 455 W7 360228091322301 16N05W17ABA1 360228 913223 535 Well 400 1/1/01 60 475 W8 360056091340801 16N05W19CCB1 360056 913408 610 Well 514 3/29/01 142 468 W9 360056091340802 16N05W19CCB2 360056 913408 610 Well 540 3/29/01 131 479 

W10 360112091324201 16N05W20BDD1 360112 913242 555 Well 32 3/28/01 12 543 W11 360110091324401 16N05W20BDD2 360110 913244 565 Well 119 3/28/01 72 493 W12 360054091310101 16N05W21DAD1 360054 913101 482 Well 140 3/29/01 16 466 W13 360029091313401 16N05W28ABC1 360029 913134 590 Well 150 3/29/01 98 492 W14 355910091340201 16N05W31CCA1 355910 913402 615 Well 173 6/6/01 100 515 W15 355923091333101 16N05W31DBA1 355923 913331 607 Well 600 6/9/75 111 496 W16 360413091341901 16N06W01AAD1 360413 913419 430 Well 112 1998 18 412 W17 360351091364101 16N06W03DBA1 360351 913641 460 Well 55 3/30/01 19 441 

Table 9. Wells and springs inventoried in the Evening Shade Spring study area--Continued[Geologic formation refers to the formation from which the spring discharges or the formation at the total depth of the well; USGS, U.S. Geological Survey; ddmmss

Site

identi-fier

(fig. 24)

Station

identification

number USGS local number

Latitude

(ddmmss)

Longitude

(ddmmss)

Altitude

of land

surface, in

feet above

NGVD

of 1929

Site

type

Well 

depth,

in feet

below

land

surface

Date of

waterlevel

measurement

Water

level, in

feet

below

land

surface

Altitud

of wate

level, 

feet abo

NGVD

of

1929 
46 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas W18 360402091382501 16N06W04BCC1 360402 913825 527 Well 78 6/7/01 19 508 

W19 360348091390901 16N06W05CAD1 360348 913909 603 Well 263 6/12/97 80 523 W20 360358091385201 16N06W05DBA1 360358 913852 605 Well 125 3/30/01 95 510 W21 360308091393001 16N06W08BCD1 360308 913930 638 Well 413 5/16/01 87 551 W22 360309091392701 16N06W08BCD2 360309 913927 642 Well 400 5/16/01 73 569 W23 360309091392702 16N06W08BCD3 360309 913927 642 Well 610 7/1/94 78 564 W24 360308091381501 16N06W09BDB1 360308 913815 630 Well 165 5/14/01 159 471 W25 360300091380001 16N06W09DBB1 360301 913756 630 Well 236 5/14/01 137 494 W26 360211091355101 16N06W14ACD1 360211 913551 570 Well 428 1/15/75 70 500 W27 360205091353401 16N06W14ADC1 360205 913534 570 Well 165 3/28/01 91 479 W28 360222091355501 16N06W14BAD1 360222 913555 560 Well 300 6/6/01 88 472 W29 360238091402301 16N06W18BAA1 360238 914023 582 Well 985 6/7/01 95 487 W30 360137091352201 16N06W23AAA1 360137 913522 600 Well 302 3/28/01 75 525 W31 360047091361201 16N06W23CCD1 360047 913612 590 Well 50 5/15/01 19 571 W32 360054091351402 16N06W24CCB2 360054 913514 640 Well unknown 5/15/01 18 623 W33 360105091343001 16N06W24DAC1 360105 913430 615 Well 157 3/28/01 138 477 W34 360059091343701 16N06W24DCA1 360059 913437 645 Well 360 3/28/01 156 489 

Table 9. Wells and springs inventoried in the Evening Shade Spring study area--Continued[Geologic formation refers to the formation from which the spring discharges or the formation at the total depth of the well; USGS, U.S. Geological Survey; ddmmss

Site

identi-fier

(fig. 24)

Station

identification

number USGS local number

Latitude

(ddmmss)

Longitude

(ddmmss)

Altitude

of land

surface, in

feet above

NGVD

of 1929

Site

type

Well 

depth,

in feet

below

land

surface

Date of

waterlevel

measurement

Water

level, in

feet

below

land

surface

Altitud

of wate

level, 

feet abo

NGVD

of

1929 
Spring Characterization 47

W35 360022091352601 16N06W25BCD1 360022 913512 600 Well 303 6/6/01 38 562 W36 355955091350201 16N06W25CDC1 355955 913502 635 Well 525 6/6/01 101 534 W37 355954091345701 16N06W25CDC2 355954 913457 620 Well unknown 6/6/01 42 578 W38 360011091362001 16N06W26CBC1 360011 913620 650 Well 800 5/14/01 105 545 W39 355945091391501 16N06W34BAB1 355955 913715 740 Well 2700 5/16/01 230 510 W40 360023091365401 16N06W27ACC1 360023 913654 650 Well 1000 5/15/01 93 557 W41 355959091390901 16N06W29DCC1 355959 913909 650 Well 252 5/16/01 64 586 W42 355922091342901 16N06W36DAC1 355922 913429 660 Well 190 6/6/01 37 623 W43 360031091411901 16N07W25ACD1 360031 914119 670 Well unknown 6/6/01 133 537 W44 360812091374101 17N06W09DBD1 360812 913741 700 Well 375 6/5/01 161 539 W45 360707091390501 17N06W17CDD1 360707 913905 540 Well unknown 6/5/01 79 461 W46 360551091353901 17N06W26ACB1 360551 913539 440 Well 1200 5/17/01 30 410 W47 360551091353902 17N06W26ACB2 360551 913539 440 Well 107 5/17/01 32 408 W48 360557091382201 17N06W28BBC1 360557 913822 620 Well 375 5/17/01 153 467 W49 360604091385401 17N06W29ABC1 360604 913854 525 Well 900 5/16/01 80 445 W50 360428091401101 17N06W31DCC1 360428 914011 520 Well 700 4/18/01 96 424 W51 360506091354401 17N06W35ABC1 360506 913544 570 Well 170 4/18/01 25 545 

Table 9. Wells and springs inventoried in the Evening Shade Spring study area--Continued[Geologic formation refers to the formation from which the spring discharges or the formation at the total depth of the well; USGS, U.S. Geological Survey; ddmmss

Site

identi-fier

(fig. 24)

Station

identification

number USGS local number

Latitude

(ddmmss)

Longitude

(ddmmss)

Altitude

of land

surface, in

feet above

NGVD

of 1929

Site

type

Well 

depth,

in feet

below

land

surface

Date of

waterlevel

measurement

Water

level, in

feet

below

land

surface

Altitud

of wate

level, 

feet abo

NGVD

of

1929 
48 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 27. Water-level contours of the Evening Shade Spring study area.

Piney

Fork

Strawberry

Rive r

Mill

Whaley

Creek

Bird

Creek

Dry

Branch

Cr eek

480

467

457

410408

477

405

460

460

557

538

660

455

545

500

460

455

485

550

495

435

520

480

440

560

400

600

640

360

680

560

560

440

480

520

520

560

480

520

480

480

520

600

600

600

560

640

640

520

480

600

560

440

545

461

539

537

623

586

557

578

534

562

489

623

571

525

487

472

479 500

494

564 471

569 551

510

523

508

441

412

492

466

543 468

475

479

455

502

401

408

368 357

0 1 2 Miles

0 1 2 Kilometers

36°

91°40' 91°30'

36°05'

Izard Co.

Sharp Co.

435

410

EXPLANAWATER-LEV

altitude at whave stood Dashed whContour inteNational Ge1929

GENERALIZ

FLOW DIRE

WELL--Num

in feet abovVertical Dat

SPRING--Nu

in feet abovDatum of 19

440

BACKBONE

Base from U.S. Geological Surveydigital data, 1:100,000

;

;

;

;

;

;

;

;

;

;

;
Spring Characterization 49

Samples collected at Evening Shade Spring had 

SIcalcite values ranging from 0.48 to 0.12, showing the 

waters are supersaturated with calcite. Values for

SIcalcite appeared to have an inverse relation with the 

quantity of discharge at the time the sample was collected. At higher discharges, the SIcalcite decreased and 

at lower discharges the value increased (table 10). 

Although it has been shown that there is not a large 

variation in spring discharge during precipitation 

events, flow velocities in the ground-water system during periods of high precipitation (late winter, early 

spring) may increase enough to decrease the contact 

time of the water with the rock because of a steepening 

of the ground-water gradient.

Nutrient concentrations at Evening Shade Spring 

generally were less than concentrations at Hughes 

Spring and Stark Spring and concentrations reported 

for undeveloped sites in the Springfield Plateau and 

Ozark aquifers (Adamski, 1997). Ammonia, ammonia 

plus organic nitrogen, nitrite, and orthophosphorus 

concentrations were below detection limits in all of the 

samples from Evening Shade Spring. Dissolved nitrite 

plus nitrate concentrations ranged from 0.44 to 0.52 

mg/L as nitrogen and dissolved phosphorus concentrations were 0.01 mg/L (table 10). 

The relation between δD and δ18O for Evening 

Shade Spring is similar to that of the global meteoric 

line (VSMOW) and followed the trend of the local 

meteoric line indicating that samples are representative 

of direct precipitation entering the aquifer system and 

not influenced by sources of water enriched in δ18O 

through evaporation (fig. 29). Samples from wells W11 

and W48 had similar isotopic chemistries as Evening 

Shade Spring. Values for δD in W11 and W48 were

-35.08 and -36.32 per mil, respectively, and for δ18O 

were -6.06 and -6.11 per mil, respectively. Spring S6 

and well W25 demonstrated an enrichment of δ18O 

and δD because of the effects of evaporation. Spring S6 

is an extreme example of the effects of evaporation 

with values of 2.84 and 3.92 per mil for δD and δ18O, 

respectively. Other constituents such as sodium, chloride, sulfate, and bromide had high concentrations in 

Spring S6 compared to other samples in the area (table 

11), indicating the chemistry may be influenced by a 

contamination source.

The δ13C data show the water discharging from 

Evening Shade Spring reflects near-equilibrium conditions between the ground water and the aquifer material. The estimated proportions of organically- and 

inorganically-derived carbon from δ13C data for 

Evening Shade Spring were calculated to be 58 percent 

and 42 percent, respectively (table 10). Similar values 

were found for the base-flow sample collected from 

Hughes Spring. 

Radiogenic isotopes (tritium and carbon-14) 

from Evening Shade Spring indicated that the discharge water is a mixture of recent recharge and submodern water (recharged prior to 1952; table 2 and 10). 

Tritium measured at Evening Shade Spring was 2.3 TU 

and the carbon-14 was 46.9 percent modern carbon. 

Although the tritium value is similar to values measured at Hughes and Stark Spring (influenced by local 

recharge), the carbon-14 value is approximately half. 

This would indicate that the water that discharges from 

Evening Shade Spring has less influx of modern carbon 

and is more indicative of a regional ground-water 

source.
50 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Table 10. Water-quality analyses from samples collected at Evening Shade Spring, 2001-2002

[ft3/s, cubic foot per second; °C, degrees Celsius; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius;

e, estimated; <, less than; μg/L, micrograms per liter; --, no data]

Constituent Sept. 4, 2001 Dec. 17, 2001 July 22, 2002 Oct. 16, 2002

Discharge, ft3/s 1.3 1.6 1.5 0.9

Water temperature, °C 17 17 17 16

Dissolved oxygen, mg/L 7.8 6.4 8.6 2.6

Specific conductance, μS/cm 352 348 355 348

pH 8.0 7.7 7.9 8.1

Bicarbonate, dissolved, mg/L 221 213 207 211

Calcium, dissolved, mg/L 40.0 41.7 42.9 43.1

Magnesium, dissolved, mg/L 19.8 19.9 20.1 19.8

Sodium, dissolved, mg/L 1.23 1.38 1.22 1.22

Potassium, dissolved, mg/L 0.66 0.68 0.60 0.61

Chloride, dissolved, mg/L 1.87 1.62 2.28 1.82

Sulfate, dissolved, mg/L 2.50 2.57 2.69 2.85

Silica, dissolved, mg/L 8.56 8.64 9.01 8.95

Bromide, dissolved, mg/L 0.037 e0.027 e0.021 0.021

Fluoride, dissolved, mg/L <0.1 e0.082 <0.1 <0.1

Iron, dissolved, μg/L <10 <10 <10 <10

Manganese, dissolved, μg/L <2 e1.61 <2 e0.89

Total dissolved solids, 

calculated, mg/L

183 184 183 184

Calcite saturation index 0.43 0.12 0.27 0.48

Hardness, mg/L as CaCO3 181 186 190 190

Ammonia plus organic nitrogen

 dissolved, mg/L as nitrogen

<0.1 <0.1 <0.1 <0.1

Nitrite, dissolved, mg/L as nitrogen <0.008 <0.008 <0.008 <0.008

Nitrite plus nitrate, dissolved, 

mg/L as nitrogen

e0.49 0.44 0.48 0.52

Phosphorus, dissolved, mg/L e0.01 0.01 0.01 0.01

Orthophosphorus, dissolved,

mg/L as phosphorus

<0.02 <0.02 <0.02 <0.02

Escherichia coli bacteria,

colonies per 100 milliliters

<1 <1 <3 <3

Fecal coliform bacteria,

colonies per 100 milliliters

<1 <1 <3 <3

Fecal streptococci bacteria,

colonies per 100 milliliters

<1 <1 <3 <3

Deuterium, ratio per mil -36.1 -- -- --

Oxygen-18, ratio per mil -6.08 -- -- --

Carbon-13, ratio per mil -14.05 -- -- --

Tritium, tritium units 2.3 -- -- --

Carbon-14, percent modern carbon 46.9 -- -- --
Spring Characterization 51

Table 11. Water-quality analyses of samples collected from three wells and one spring in the Evening Shade Spring study 

area on October 16 and 17, 2002

[°C, degrees Celsius; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; <, less than; μg/L, micrograms per liter]

Site identifier (fig. 24)

Constituent S6 W11 W25 W48

Site type Spring Well Well Well

Contributing geologic unit Everton Formation Everton Formation Everton Formation Cotter Dolomite

Water temperature, °C 18 18 15 16

Dissolved oxygen, mg/L 5.6 4.5 3.4 3.6

Specific conductance, μS/cm 574 89 365 555

pH 8.8 6.4 7.4 7.8

Bicarbonate, dissolved, mg/L 250 43 228 339

Calcium, dissolved, mg/L 46.8 7.26 42.1 62.9

Magnesium, dissolved, mg/L 34.2 3.91 20.5 33.5

Sodium, dissolved, mg/L 15.7 1.80 1.26 1.98

Potassium, dissolved, mg/L 11.0 0.43 0.62 0.98

Chloride, dissolved, mg/L 20.6 2.62 2.33 15.0

Sulfate, dissolved, mg/L 33.2 0.53 1.13 4.30

Silica, dissolved, mg/L 0.13 12.35 11.36 9.89

Bromide, dissolved, mg/L 15.7 e0.015 0.030 0.018

Fluoride, dissolved, mg/L <0.1 <0.1 <0.1 <0.1

Iron, dissolved, μg/L <10 24.08 e7.12 <10

Manganese, dissolved, μg/L <2 4.42 <2 e1.19

Total dissolved solids,

calculated, mg/L

285 50.1 192 295

Calcite saturation index 0.88 -2.37 -0.17 0.55

Hardness, mg/L as CaCO3 258 34.3 190 295

Deuterium, ratio per mil 2.84 -36.32 -26.41 -35.08

Oxygen-18, ratio per mil 3.92 -6.11 -4.04 -6.06
52 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 28. Relation of ground-water samples from Evening Shade Spring and other wells and springs in northern Arkansas 

and southern Missouri.

SODIUM PLUS POTASSIUM

CARBONATE PLUS BICARBONATE

SULFATE PLUS CHLORIDE

CALCIUM PLUS MAGNESIUM

CaSO

(gypsum,

anhydrite)

4

CaCO

CaMg(CO )

(calcite,

dolomite)

3

3 2 NaCI

(halite)

NaHCO3

EXPLANATION
Spring Characterization 53

Figure 29. Relation of deuterium and oxygen-18 isotope ratios in ground-water samples from Evening Shade Spring and other 

wells and springs in northern Arkansas and southern Missouri.

δ OXYGEN-18, IN PER MIL

-7.5 -7.0 -6.5 -6.0 -5.5 -5.0 -4.5 -4.0 -3.5

δDEUTERIUM, IN PER MIL

-50

-45

-40

-35

-30

-25

Samples of wells and springs

from U.S. Geological Survey

National Water Inventory

System database

Sample from Evening Shade Spring

Samples from wells and

springs in the study area

δ deuterium = 7.4(δ oxygen-18)+9.4

(LOCAL METEORIC LINE)

METEORIC WATER LINE (VIENNA STANDARD MEAN OCEAN WATER)

W25

W11

W48

Roaring Spring

Study Area Description

The Roaring Spring study area lies in the Salem 

Plateau physiographic province (fig. 1) and occurs 

largely within dolomites of Ordovician age. The altitude of the study area ranges from 325 to 928 ft above 

NGVD of 1929. Land use in the area consists primarily 

of deciduous and evergreen forest land (82 percent) and 

agricultural land (14 percent). Urban land use consists 

of less than 2 percent of the study area. Water and transitional land uses consists of 2 percent of the study area 

(Vogelmann and others, 2001).

Annual mean temperatures recorded at Hardy 

(fig.1) for calendar years 2001 and 2002 were 17 °C 

and 16 °C, respectively, which were above normal (+4 

°C and +3 °C, respectively) based on a 54-year period 

from 1948 to 2002 (National Oceanic and Atmospheric 

Administration, 2002). The annual rainfall recorded at 

Hardy was 42 inches for 2001 and 62 inches for 2002 

(National Oceanic Atmospheric Administration, 2001; 

2002). The average annual rainfall for Hardy is 45 

inches (Hoare, 1996).

Hydrogeology

The Cotter Dolomite and the Jefferson City 

Dolomite are the major geologic formations exposed in 

the Roaring Spring study area. There also are some 

small areas of the Powell Dolomite and Everton Formation in the southwestern corner of the study area (fig. 

30). At depth, the geology is similar to the Evening 

Shade Spring study area, with the Roubidoux Formation and Gasconade Dolomite present as formations 

that are commonly used for higher yield water-supply 

wells. Many of the residential wells in the study area 

are completed in the Cotter Dolomite and the Jefferson 

City Dolomite (table 12; fig. 31). All of the formations 

in the study area are considered part of the Ozark aquifer.

Roaring Spring discharges near the contact 

between the Cotter Dolomite and the Jefferson City 

Dolomite. Similar to Evening Shade Spring, the location of the Roaring Spring discharge may be from the 

concentration of regional flow in formations composing the Ozark aquifer through enlarged conduits or 

fractures (fig. 32). Raccoon Spring (S2) near Roaring 

Spring has similar characteristics (fig. 31).
54 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 30. Geology of the Roaring Spring study area.

South

River

Creek

Spring

Wild

Horse Fork

Spring

River

Oc

Oc

Oc

Oc

Ojc

Ojc

Ojc

Ojc

Opw

Oe

Roaring

Spring

67

412

289

175

0 1 2 

0 1 2 Kilomete

36°21'36°18'

91°40'48" 91°31'12"

Fulton Co.

Sharp Co.

Cherokee

Village

Oe

Oc

Opw

Ojc

EXPLANATION

Everton DolomitePowell FormationCotter Dolomite

Jefferson City DolomiteSinkholeSpring

Geology modified from E.E. GlickU.S. Geological Survey, unpub data., 1973Base from U.S. Geological Surveydigital data, 1:100,000
Spring Characterization 55

Table 12. Wells and springs inventoried in the Roaring Spring study area[Geologic formation refers to the formation from which the spring discharges or the formation at the total depth of the well; USGS, U.S. Geological Survey; ddmmss

Site

identifier

(fig. 31)

Station

identification

number USGS local number

Latitude

(ddmmss)

Longitude

(ddmmss)

Altitude

of land

surface, in

feet above

NGVD

of 1929

Site

type

Well 

depth,

in feet

below

land

surface

Date of

waterlevel

measurement

Water

level, in

feet

below

land

surface

Altitude

of waterlevel, in

feet above

NGVD

of

1929 

S1 07069297 19N06W12BDA1SP 361908 913431 400 Spring -- -- -- 400 S2 361857091325701 19N05W08BCD1SP 361857 913237 400 Spring -- -- -- 400 S3 361617091344201 19N06W25CAB1SP 361617 913442 697 Spring -- -- -- 697 S4 361545091342101 19N06W36ABD1SP 361545 913421 635 Spring -- -- -- 635 S5 362122091352201 20N06W26DCD1SP 362122 913522 500 Spring -- -- -- 500 W1 361945091312401 19N05W04BCD1 361945 913124 700 Well Unknown 7/26/01 167 533 W2 361944091312101 19N05W04CAB1 361944 913121 690 Well 1,420 10/2/01 183 507 W3 361855091333101 19N05W07BDC1 361855 913331 490 Well Unknown 3/22/01 74 416 W4 361854091333201 19N05W07BDC2 361854 913332 505 Well 77 3/22/01 71 434 W5 361826091301701 19N05W10CDC1 361826 913017 500 Well 1,100 8/24/01 96 404 W6 361644091304001 19N05W21DDD1 361644 913040 700 Well Unknown 7/25/01 128 572 W7 361926091345901 19N06W01CCC1 361926 913459 560 Well 360 6/20/01 103 457 W8 362009091354301 19N06W02BDB1 362009 913543 440 Well 42 3/22/01 11 429 W9 361844091334701 19N06W07CBC1 361844 913347 440 Well 100 6/21/01 35 405 W10 361917091354701 19N06W11BAC1 361917 913547 608 Well 269 7/26/01 157 451 W11 361832091345101 19N06W12CCD1 361832 913451 602 Well Unknown 7/25/01 179 423 W12 361853091341601 19N06W12DBA1 361853 913416 520 Well 160 3/22/01 113 407 W13 361809091384201 19N06W17DBB1 361809 913842 560 Well 65 6/19/01 31 529 W14 361803091383601 19N06W17DBD1 361803 913836 607 Well 180 6/19/01 63 544 W15 361707091383101 19N06W20DCA1 361707 913831 825 Well 158 1/4/01 89 736 W16 361629091352001 19N06W26ACA1 361629 913520 780 Well 261 6/20/01 90 690 
56 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas W17 361621091353801 19N06W26CAA1 361621 913538 750 Well 400 7/25/01 124 626 

W18 361644091360701 19N06W27AAA1 361644 913607 750 Well 150 6/20/01 73 677 W19 361639091363101 19N06W27ABC1 361639 913631 700 Well 173 6/20/01 42 658 W20 361646091364001 19N06W27BAA1 361646 913640 720 Well 323 6/20/01 60 660 W21 361628091364001 19N06W27BDD1 361628 913640 690 Well 280 6/20/01 56 634 W22 361616091365401 19N06W27CBD1 361616 913654 670 Well 280 6/20/01 43 627 W23 361647091381601 19N06W29AAD1 361647 913816 770 Well 128 7/5/01 39 731 W24 361548091351801 19N06W35ABD1 361548 913518 682 Well 520 6/21/01 60 622 W25 361549091344401 19N06W36BAB1 361549 913444 665 Well 70 6/20/01 28 637 W26 362107091311701 20N05W28CDC1 362107 913117 540 Well Unknown 7/26/01 36 504 W27 362151091320001 20N05W29AAC1 362151 913200 600 Well Unknown 7/26/01 149 451 W28 362046091331501 20N05W31ACD1 362046 913315 680 Well Unknown 7/26/01 165 515 W29 362128091363101 20N06W27DBC1 362128 913631 550 Well 165 3/21/01 65 485 W30 362045091352801 20N06W35DBB1 362045 913528 505 Well 180 3/21/01 67 438 W31 362118091381201 20N06W33BBB1 362118 913812 498 Well 42 8/24/01 7 491 W32 361849091300301 19N05W10CAA1 361849 913003 395 Well 150 10/12/01 8 387 

Table 12. Wells and springs inventoried in the Roaring Spring study area [Geologic formation refers to the formation from which the spring discharges or the formation at the total depth of the well; USGS, U.S. Geological Survey; ddmmss

Site identi- fier (fig. 31) Station identification number USGS local number Latitude (ddmmss) Longitude (ddmmss) Altitude of land surface, in feet above NGVD of 1929 Site type Well depth, in feet below land surface Date of water- level measure- ment Water level, in feet below land surface Altitude of water- level, in feet above NGVD of 1929 
Spring Characterization 57

Roaring Spring discharges near the contact 

between the Cotter Dolomite and the Jefferson City 

Dolomite. Similar to Evening Shade Spring, the location of the Roaring Spring discharge may be from the 

concentration of regional flow in formations of the 

Ozark aquifer through enlarged conduits or fractures 

(fig. 32). Raccoon Spring (S2) near Roaring Spring has 

similar characteristics (fig. 31).

Discharge, Temperature, and Precipitation

The discharge for Roaring Spring did not vary in 

response to precipitation events but did increase 

through time for the period of record (June 29, 2001 to 

October 1, 2002) (fig. 33) The mean daily discharge 

computed from the springhouse ranged from 4.8 to 7.2 

ft3

/s and the mean discharge was 5.7 ft3/s for the period 

of record (Brossett and Evans, 2003). 

On average, the base-flow discharge for Roaring 

Spring accounted for approximately 99 percent of the 

total discharge volume for the period. The lowest baseflow discharge occurred during the period of September through December of 2001 and steadily increased 

and remained high for the remainder of the monitoring 

period (fig. 33). The increase in discharge appears to be 

a reflection of the increase in precipitation during the 

period of December 2001 to June 2002. Discharge 

exceeded base flow by more than 5 percent during only 

2 percent of the monitoring period (June 29, 2001 to 

October 1, 2002). The small peaks that were evident 

during periods of intense rainfall indicated a small 

component of local recharge. The local recharge may 

occur immediately adjacent to the spring as infiltration 

through the shallow subsurface, but not at substantial 

volumes. The ratio of peak flow to base flow for Roaring Spring was calculated as 1.5 based on the entire 

period of record, indicating a slow-response spring 

(White, 1988). The discharge characteristics were similar to Evening Shade Spring and contrasted with the 

fast response, storm input type of discharge that was 

observed at Hughes and Stark Springs. 

Figure 31. Distribution of wells and springs in the Roaring Spring study area. 

Fulton Co.

Sharp Co.

South

River

Creek

Spring

Wild

Horse

Fork

Spring

River

W16 W19

W9

W8

W7

W5

W4

W3

W2 W1

W6

W31

W32

W30

W29

W28

W27

W26

W25 W24

W23

W22

W21

W20 W18

W17

W15

W14

W13

W12

W11

W10

S5

S4

S3

S1 S2

Cherokee

Village

67

412

289

175

0 1 2 Miles

0 1 2 Kilometers

36°18'

36°21'

91°40'48" 91°31'12"

EXPLANATION

Well used for geophysical

survey

Well sampled for water

quality

Spring

Spring sampled for water

quality

Well by contributing

hydrogeologic unit

(Identifier refers to

table 12)

Unknown

Cotter Dolomite

Jefferson City Dolomite

Gunter Sandstone Member

of the Gasconade Dolomite

Roaring

Spring

Base from U.S. Geological Survey

digital data, 1:100,000
58 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 32. Conceptual model of ground-water flow to Roaring Spring.

South Fork Spring River

Roaring Spring CO

JEFFERSON CIT

NORTH 

South Fork Spring River

;

;

;

;

;

;

;

;

EXPLANATIONGeneralized flow

; direction
Spring Characterization 59

Figure 33. Daily discharge, rainfall, and water temperature recorded at Roaring Spring. DISCHARGE, IN CUBIC FEET PER SECOND

0.01

0.1

1

10

100

RAINFALL, IN INCHES

0

1

2

3

4

DATE

TEMPERATURE, IN

DEGREES CELSIUS

8

10

12

14

16

18

20

22

24

2001 2002

July Sept Nov Jan Mar May July Sept 

July Sept Nov Jan Mar May July Sept 

July Sept Nov Jan Mar May July Sept 

Water-quality

sample collected

October 16, 2002

TOTAL

MEASURED

WATER-QUALITY SAMPLE

BASEFLOW
60 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 34. Water-level contours of the Roaring Spring study area.

Fulton Co.

Sharp Co.

South

River

Creek

Spring

Wild

Horse

Fork

Spring

River

690 658

387

491

438

485

515

451

504

637

622

731

627

634

660 677

626

736

544

529

407

423

451

405

429

457

404

434416

507

533

500

635

697

400

400

572

520

560

600

480

440

640

400

680

720

680

520

480

Roaring

Spring

Cherokee

Village

0 1 2 Miles

0 1 2 Kilometers

91°40'48" 91°31'12"

36°18'

36°21'

;

;

;

410

435

440 WATER-LEVEL CONTOUR--Shows altitude at

which water level would stood in tightly cased

wells (2001). Dashed where approximately

located. Contour interval 20 feet. Datum is

National Vertical Datum of 1929

GENERALIZED GROUND-WATER FLOW

DIRECTION

WELL--Number is hydraulic head in feet above

the National Geodetic Vertical Datum of 1929

SPRING--Number is hydraulic head in feet above

the National Geodetic Vertical Datum of 1929

EXPLANATION

;

;

;

;

;

;

;

Base from U.S. Geological Survey

digital data, 1:100,000

The water temperature recorded at Roaring 

Spring ranged from 17.1 to 17.2 °C for the period of 

record (fig. 33). The relatively stable discharge and 

temperature recorded for Roaring Spring indicates a 

large, steady, regional source of water. 

Water-Level Contours

Water-level contours constructed from static 

water levels measured in 32 wells and 5 springs in 2001 

(table 13) generally followed land-surface topography 

in the area and indicate that ground water flows towards 

the South Fork Spring River in the central portion of the 

study area and the Spring River in the northeast (fig. 

34). The highest water levels were found in the southwestern portion of the study area. The linear depression 

in the water-level altitude that occurs in the central and 

eastern parts of the study area indicates an area of 

ground-water discharge and corresponds with the location of Roaring (S1) and Raccoon (S2) Springs. The 

contours in the study area follow a similar pattern to the 

regional flow of the Ozark aquifer constructed by Pugh 

(1998) and Schrader (2001). 

Recharge Area Characterization

The discharge, geochemical, and hydrogeologic 

data indicate that the discharge for Roaring Spring 

mostly is representative of a regional ground-water 

flow system (Ozark aquifer) and does not allow for a 

distinct boundary to be delineated for the recharge area 

contributing to the spring. The recharge area could 

include relatively remote locations where hydrogeologic units composing the Ozark aquifer are exposed 
Spring Characterization 61

Table 13. Water-quality analyses from samples collected at Roaring Spring, 2001-2002

[ft3/s, cubic foot per second; °C, degrees Celsius; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius;

e, estimated; <, less than; μg/L, micrograms per liter; --, no data]

Constituent Sept. 4, 2001 Dec. 17, 2001 July 22, 2002 Oct. 16, 2002

Discharge, ft3/s 4.8 5.9 6.0 6.2

Water temperature, °C 17 16 17 17

Dissolved oxygen, mg/L 5.4 5.2 5.2 3.4

Specific conductance, μS/cm 491 483 491 493

pH 7.7 7.7 7.6 7.7

Bicarbonate, dissolved, mg/L 315 317 305 335

Calcium, dissolved, mg/L 53.1 54.2 55.9 56.2

Magnesium, dissolved, mg/L 31.7 31.0 31.3 31.0

Sodium, dissolved, mg/L 1.42 1.38 1.40 1.39

Potassium, dissolved, mg/L 1.02 1.04 0.97 0.94

Chloride, dissolved, mg/L 2.02 1.48 2.54 1.22

Sulfate, dissolved, mg/L 3.43 3.26 2.95 2.93

Silica, dissolved, mg/L 9.16 9.02 9.58 9.50

Bromide, dissolved, mg/L 0.040 e0.024 e0.022 e0.022

Fluoride, dissolved, mg/L <0.1 <0.1 <0.1 <0.1

Iron, dissolved, μg/L <10 <10 <10 <10

Manganese, dissolved, μg/L <2 <2 e1.19 4.42

Total dissolved solids,

calculated, mg/L

257 258 255 269

Calcite saturation index 0.33 0.31 0.21 0.35

Hardness, mg/L as CaCO3 263 163 269 270

Ammonia plus organic nitrogen

 dissolved, mg/L as nitrogen

<0.1 <0.1 0.38 <0.1

Nitrite, dissolved, mg/L as nitrogen <0.008 <0.008 <0.008 <0.008

Nitrite plus nitrate, dissolved,

mg/L as nitrogen

e0.17 0.15 0.16 0.18

Phosphorus, dissolved, mg/L e0.005 e0.004 e0.004 0.006

Orthophosphorus, dissolved,

mg/L as phosphorus

<0.02 <0.02 <0.02 <0.02

Escherichia coli bacteria,

colonies per 100 milliliters

-- <1 76 <1

Fecal coliform bacteria,

colonies per 100 milliliters

-- <1 61 <1

Fecal streptococci bacteria,

colonies per 100 milliliters

-- <1 258 <1

Deuterium, ratio per mil -38.1 -- -- --

Oxygen-18, ratio per mil -6.21 -- -- --

Carbon-13, ratio per mil -13.17 -- -- --

Tritium, tritium units 5.1 -- -- --

Carbon-14, percent modern carbon 53.1 -- -- --
62 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

and have sufficient porosity and hydraulic conductivity 

to convey water that falls as precipitation to the subsurface. However, the discharge data and fecal indicator 

bacteria samples did show that some local influences 

may affect the spring discharge, but probably reflect 

conditions immediately adjacent to the location of 

Roaring Spring. 

Geochemistry

The major ion analyses from Roaring Spring 

(table 13) and from wells and springs in the study area 

(table 14) demonstrate calcium bicarbonate type water 

typical of the Ozark aquifer (fig. 35). All samples collected from Roaring Spring and from the other wells 

and springs in the study area had calcium to magnesium ratio values of 1.1, indicating contribution from a 

dolomitic mineralogy (White, 1988) that is representative of units of the Ozark aquifer and similar to Evening 

Shade Spring. The chemistry of Raccoon Spring (S2) 

was similar to Roaring Spring with respect to the field 

parameter values (pH, specific conductance, and temperature) and major ion concentrations (tables 13 and 

14). The samples collected from other springs and 

wells in the study area also were similar, but generally 

had higher total dissolved solid concentrations and 

hardness values. 

Samples collected at Roaring Spring had SIcalcite

values ranging from 0.21 to 0.35, indicating the waters 

are supersaturated with calcite, regardless of the flow 

conditions. The other wells and springs, except for 

Raccoon Spring (S2), had waters more saturated with 

respect to calcite, ranging in value from 0.60 to 0.71 

(table 14).

Nutrient concentrations at Roaring Spring were 

lower than concentrations for all of the other springs 

sampled for this study. Concentrations of ammonia, 

nitrite, and orthophosphorus were below detection limits (table 13). Concentrations of ammonia plus organic 

nitrogen were below detection levels except for one 

sample that had a concentration of 0.38 mg/L as nitrogen. Concentrations of dissolved nitrate plus nitrite 

ranged from 0.15 to 0.18 mg/L as nitrogen and dissolved phosphorus concentrations were all equal to or 

less than 0.006 mg/L. 

Wastewater constituents analyzed for Roaring 

Spring did not indicate any influence from contamination sources. However, fecal indicator bacteria indicated some local influence on the spring. Wastewater 

constituents analyzed from one sample did not have 

any constituents with concentrations greater than the 

detection levels. Fecal indicator bacteria were found 

only in one sample collected during a period of no precipitation from Roaring Spring (table 13). 

The relation between δD and δ18O of the Roaring Spring is similar to that of the global meteoric line 

(VSMOW) and generally followed the trend of the 

local meteoric line indicating that samples are representative of direct precipitation entering the aquifer 

system and not influenced by sources of water enriched 

in δ18O through evaporation. The δD and δ18O values 

for Roaring Spring were -38.10 and -6.21 per mil, 

respectively (table 13). Some variation was evident 

between other sites sampled in the study area (fig. 36 

and table 14). Well W30 had the most similar isotopic 

signature as Roaring Spring with δD and δ18O values 

of -38.64 and -6.26 per mil, respectively. Samples from 

spring S5 and well W7 demonstrated source waters that 

were more enriched in δD and δ18O. Raccoon Spring 

(S2) was more enriched in δ18O, although the isotopic 

signature was similar to the local meteoric line. 

The δ13C data show the water discharging from 

Roaring Spring reflect near-equilibrium conditions 

between the ground water and the aquifer material. 

Inorganically-derived δ13C was estimated at 45 percent of the total δ13C content and organically-derived 

δ13C constituted 55 percent. Proportions of inorganically- and organically-derived carbon at Roaring 

Spring were similar to Evening Shade Spring sample 

and the base-flow sample collected from Hughes 

Spring.

Radiogenic isotopes (tritium and carbon-14) 

from Roaring Spring indicated that the discharge water 

is of relatively modern age (recharged within less than 

5 to 10 years; tables 2 and 13). Tritium measured at 

Roaring Spring was 5.1 TU and the carbon-14 was 53.1 

percent modern carbon. The tritium value was greater 

than values measured at Hughes and Stark Spring 

(influenced by local recharge), and the carbon-14 value 

was approximately half. This would indicate that the 

water that discharges from Roaring Spring has less 

influx of modern carbon and is more indicative of a 

regional ground-water source.
Spring Characterization 63

Table 14. Water-quality analyses of samples collected from two wells and two springs in the Roaring Spring study area on 

October 16 and 17, 2002

[°C, degrees Celsius; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; μg/L, microgram per liter;

<, less than; --, no data; e, estimated]

Site identifier (fig. 31)

Constituent S2 S5 W7 W30

Site type Spring Spring Well Well

Contributing geologic unit Roubidoux Formation Cotter Dolomite Jefferson City Dolomite Jefferson City Dolomite

Water temperature, °C 18 15 16 15

Dissolved oxygen, mg/L 2.1 4.76 -- --

Specific conductance, μS/cm 497 630 720 749

pH 7.6 7.7 7.8 7.8

Bicarbonate, dissolved, mg/L 334 433 482 438

Calcium, dissolved, mg/L 56.6 73.6 84.7 75.1

Magnesium, dissolved, mg/L 31.2 41.2 45.0 40.0

Sodium, dissolved, mg/L 1.47 1.32 0.87 1.51

Potassium, dissolved, mg/L 0.9 0.96 0.93 1.06

Chloride, dissolved, mg/L 1.79 1.08 1.68 2.30

Sulfate, dissolved, mg/L 3.00 2.81 6.11 1.30

Silica, dissolved, mg/L 9.36 11.02 10.83 13.77

Bromide, dissolved, mg/L 0.025 0.022 0.020 0.021

Fluoride, dissolved, mg/L <0.1 <0.1 <0.1 <0.1

Iron, dissolved, μg/L <10 <10 <10 <10

Manganese, dissolved, μg/L 3.62 3.30 e1.29 e2.42

Total dissolved solids,

calculated, mg/L

269 345 387 350

Calcite saturation index 0.31 0.60 0.71 0.63

Hardness, mg/L as CaCO3 270 353 397 352

Deuterium, ratio per mil -32.60 -35.79 -33.83 -38.64

Oxygen-18, ratio per mil -5.67 -6.39 -6.26 -6.26
64 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

Figure 35. Relation of ground-water samples from Roaring Spring and other wells and springs in northern Arkansas and 

southern Missouri.

SODIUM PLUS POTASSIUM

CARBONATE PLUS BICARBONATE

SULFATE PLUS CHLORIDE

CALCIUM PLUS MAGNESIUM

CaSO

(gypsum,

anhydrite)

4

CaCO

CaMg(CO )

(calcite,

dolomite)

3

3 2 NaCI

(halite)

NaHCO3

EXPLANATION
Summary 65

Figure 36. Relation of deuterium and oxygen-18 isotope ratios in the ground-water sample from Roaring Spring and other 

wells and springs in northern Arkansas and southern Missouri.

δ OXYGEN-18, IN PER MIL

-7.5 -7.0 -6.5 -6.0 -5.5 -5.0

δDEUTERIUM, IN PER MIL

-50

-45

-40

-35

-30

-25

Samples of wells and springs

from U.S. Geological Survey

National Water Inventory

System database

Sample from Roaring Spring

Samples from wells and

springs in study area

δ deuterium = 7.4(δ oxygen-18)+ 9.4

(LOCAL METEORIC LINE)

METEORIC WATER LINE (VIENNA STANDARD MEAN OCEAN WATER)

W30

S5

S2

W7

SUMMARY

In October 2000, a study was undertaken by the 

U.S. Geological Survey (USGS) in cooperation with 

the Arkansas Department of Health to determine the 

hydrogeologic characteristics, including the extent of 

the local recharge area, for four springs used for publicwater supply in northern Arkansas. The four springs 

included in the study are Hughes Spring, Stark Spring, 

Evening Shade Spring, and Roaring Spring. Characterization of the recharge areas is important because of the 

karst terrain common in northern Arkansas and 

because land use proximal to the springs included 

activities with potentially harmful impacts to springwater quality. 

An integrated approach to determine the hydrogeologic characteristics, including the extent of the 

local recharge area, of the four springs incorporated 

tools and methods of hydrology, structural geology, 

geomorphology, geophysics, and geochemistry. An 

assessment of the local geology through previous mapping, borehole geophysics, and field investigation was 

completed in each study area to develop a conceptual 

model of the local ground-water flow system. An analysis of continuous discharge, water temperature, and 

precipitation was completed to determine the local 

recharge area size and characteristics of the flow system. Discharge and precipitation data for selected 

storms were used to determine the local recharge area 

through a water-balance approach for Stark Spring. 

Water-level contour maps were constructed from well 

and spring data to show the configuration of the water 

table and determine ground-water flow directions. 

Qualitative ground-water tracer tests also were completed to determine recharge area boundary locations 

and to estimate ground-water flow velocities for 

Hughes and Stark Springs. Water-quality samples were 

collected at each spring to determine the geochemistry 

of the contributing geologic units and the susceptibility 

of the springs to contamination. Samples were analyzed for major ions, nutrients, fecal indicator bacteria, 

wastewater constituents, and stable and radiogenic isotopes.

Hughes Spring supplies water for the city of 

Marshall, Arkansas, and the surrounding area. 

Recharge to the spring occurs mainly from the Boone 

Formation that comprises the Springfield Plateau aquifer. The mean annual discharge for Hughes Spring was 

2.9 ft3

/s for water year 2001 and 5.2 ft3/s for water year 
66 Hydrogeologic Characteristics of Four Public Drinking-Water Supply Springs in Northern Arkansas

2002. Water-level contours show that ground-water 

generally follows the land-surface topography and 

flows generally to the northwest in the study area. 

Ground-water tracer tests indicate that the recharge 

area for Hughes Spring generally coincides with the 

surface drainage area (15.8 mi2

) and that Hughes 

Spring is directly connected to the surface flow in 

Brush Creek.

The geochemistry of Hughes Spring demonstrated variations with flow conditions and the influence of surface-runoff in the recharge area. Calcite 

saturation indices, total dissolved solids concentrations, and hardness demonstrate noticeable differences 

with flow conditions reflecting the reduced residence 

time and interaction of water with the source rock at 

high-flow conditions for Hughes Spring. Concentrations of fecal indicator bacteria also demonstrated a 

substantial increase during high-flow conditions, indicating that a non-point source of bacteria possibly from 

livestock may enter the system. Conversely, nutrient 

concentrations did not vary with flow and were similar 

to concentrations reported for undeveloped sites in the 

Springfield Plateau and Ozark aquifers (Adamski, 

1997). δD and δ18O data show that the Hughes Spring 

discharge is representative of direct precipitation and 

not influenced by water enriched in δ18O through 

evaporation. δ13C data show an enrichment of organically-derived carbon during high-flow conditions, indicating a substantial component of the recharge water 

interacts with the surface material (soil and regolith) in 

the recharge area before entering the ground-water system for Hughes Spring. Tritium data for Hughes Spring 

indicate that the water discharging from the spring is a 

mixture of recent recharge and sub-modern water 

(recharged prior to 1952).

Stark Spring discharges at land surface from the 

Boone Formation and supplies water for the city of 

Cushman, Arkansas, and the surrounding area. The 

mean annual discharge for Stark Spring was 0.5 ft3

/s 

for water year 2001 and 1.5 ft3/s for water year 2002. 

Analyses of discharge data show that Stark Spring has 

a fast response to surface runoff and the estimated 

recharge area (0.79 mi2

) is larger than the surface drainage area (0.34 mi2

). Ground-water tracer tests and the 

outcrop of the Boone Formation indicate that most of 

the recharge area extends outside the surface drainage 

area.

Similar to Hughes Spring, the geochemistry of 

Stark Spring varied with flow conditions. Calcite saturation indices, total dissolved solids concentrations, 

and hardness demonstrate noticeable differences with 

flow conditions reflecting the reduced residence time 

and interaction of water with the source rock at high 

discharges for Stark Spring. In contrast to Hughes 

Spring, concentrations of fecal indicator bacteria demonstrated a decrease during high-flow conditions, and 

may reflect dilution and the lack of pastureland or other 

sources of non-point contamination in the Stark Spring 

recharge area. Nitrite plus nitrate concentrations did 

not vary with flow and were less than concentrations 

reported for undeveloped sites in the Springfield Plateau and Ozark aquifers (Adamski, 1997). Concentrations of phosphorus and orthophosphorus were slightly 

higher than concentrations reported for undeveloped 

sites in the Springfield Plateau and Ozark aquifers 

(Adamski, 1997). δD and δ18O data show that the Stark 

Spring discharge is representative of direct precipitation and not influenced by water enriched in δ18O 

through evaporation. δ13C data indicate that the 

recharge has little interaction with the soils and regolith 

in the recharge area before entering the ground-water 

system for Stark Spring. Tritium data for Stark Spring 

indicate that the water discharging from the spring is a 

mixture of recent recharge and sub-modern water 

(recharged prior to 1952).

Evening Shade and Roaring Springs originate 

from geologic formations composing the Ozark aquifer. The springs provide the water supply for the communities of Evening Shade and Cherokee Village, 

respectively, and the surrounding areas. The mean 

annual discharge for Evening Shade Spring was 1.44 

ft3

/s for water year 2001 and 1.24 ft3/s for water year 

2002. Roaring Spring had a mean discharge of 5.7 ft3

/s 

for the period of record (July 2001 to October 2002). 

Little variation in discharge and temperature was evident during high-flow events and throughout the monitoring period indicating that spring discharge is 

dominated by regional ground-water flow with small 

portions of local recharge. As a result, a local recharge 

area could not be delineated, as the area could include 

relatively remote locations where geologic formations 

composing the Ozark aquifer are exposed and have sufficient porosity and hydraulic conductivity to convey 

water that falls as precipitation to the subsurface. 

Water-level contours showed ground-water flow predominately towards the major rivers in each study area, 

similar to regional flow patterns.

Analyses of major ion concentrations for 

Evening Shade Spring and Roaring Spring indicated 

that the source water is a calcium bicarbonate type from 
References 67

a dolomitic mineralogy representative of the Ozark 

aquifer. Nutrient concentrations generally were lower 

than at Hughes and Stark Springs. Fecal indicator bacteria were not detected at Evening Shade Spring and 

were detected in only one sample from Roaring Spring. 

δD and δ18O data show that the discharge from 

Evening Shade Spring and Roaring Spring is representative of direct precipitation and not influenced by 

water enriched in δ18O through evaporation. Tritium 

data for Evening Shade Spring indicate that the discharge water is a mixture of recent recharge and submodern water (recharged prior to 1952). Discharge 

water for Roaring Spring was determined to be of relatively modern age (recharged less than 5 to 10 years).

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