U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2019–5016

Prepared in Collaboration with the University of Arkansas Department of Geosciences

Interpretation of Dye Tracing Data Collected 

November 13–December 2, 2017, at the Savoy Experimental 

Watershed as part of the Advanced Groundwater Field 

Techniques in Karst Terrains Course, Savoy, Arkansas
Cover. Fluoroscein dye entering the Illinois River downstream of Wow Spring near Savoy, Arkansas (photograph taken by 

Cassi Crow, U.S. Geological Survey). 

Top Left. Students observing dye 

emerging from Wow Spring near 

Savoy, Arkansas (photograph taken by 

Eve Kuniansky, U.S. Geological Survey).

Top Right. RhodamineWT dye 

emerging from Langle Spring and 

coloring the water behind the weir near 

Savoy, Arkansas (photograph taken by 

Cassi Crow, U.S. Geological Survey).

Bottom Right. RhodamineWT dye

injection at sinking stream upgradient

of Langle Spring, Savoy, Arkansas

(photograph taken by Joshua Blackstock, 

University of Arkansas).
Interpretation of Dye Tracing Data Collected 

November 13–December 2, 2017, at the Savoy 

Experimental Watershed as part of the 

Advanced Groundwater Field Techniques in 

Karst Terrains Course, Savoy, Arkansas

By Eve L. Kuniansky, Joshua M. Blackstock, Daniel M. Wagner, and 

J. Van Brahana

Prepared in Collaboration with the University of Arkansas 

Department of Geosciences

Scientific Investigations Report 2019–5016

U.S. Department of the Interior

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

DAVID BERNHARDT, Secretary

U.S. Geological Survey

James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2019

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as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:

Kuniansky, E.L., Blackstock, J.M., Wagner, D.M., and Brahana, J.V., 2019, Interpretation of dye tracing data collected, 

November 13–December 2, 2017, at the Savoy Experimental Watershed as part of the Advanced Groundwater Field 

Techniques in Karst Terrains Course, Savoy, Arkansas: U.S. Geological Survey Scientific Investigations Report 

2019–5016, 41 p., https://doi.org/10.3133/sir20165016.

ISSN 2328-0328 (online)
iii

Acknowledgments

Field method courses require intensive logistical effort in planning and arranging equipment 

and qualified equipment operators. This first U.S. Geological Survey (USGS) course GW2227 

Advanced Groundwater Field Techniques in Karst Terrains was in planning stages with 

hydrologists from the USGS Water Mission Area offices in Little Rock and Fayetteville, 

Arkansas, and Austin, Texas; faculty at the University of Arkansas; and the USGS Water Mission 

Area Groundwater Specialists at Headquarters beginning in earnest in 2014. The course 

would not have happened if not for the assistance of faculty members from the Department of 

Geosciences, University of Arkansas (UA). Emeritus Professor J. Van Brahana, who set up the 

Savoy Experimental Watershed (SEW) in the pastures of the Department of Animal Science beef 

farm, has conducted numerous UA HydroDays workshops, conducted numerous student research 

projects at the site, and assisted with the dye tracer testing part of the course. Associate 

Professor Matt Covington provided the use of two submersible field fluorometer/data loggers 

and use of his laboratory and laboratory spectra-fluorometer for the quantitative dye tracing part 

of the course. Adjunct Professor Fred Paillet assisted in teaching the borehole dye dilution part 

of the course. Additionally, Matt Covington allowed Joshua Blackstock, a Ph.D. candidate at 

UA, to use his laboratory for developing standards and for conducting work related to the tracer 

tests; Joshua Blackstock also assisted in teaching and conducting the field exercises for both 

the point-to-point and quantitative dye tracing.

Finally, thanks go to the USGS Texas Water Science Center for sending geophysicists, 

equipment, and instructors to help with the surface and borehole geophysics and the USGS 

Branch of Geophysics for supporting the course by providing temperature equipment and an 

instructor for the course.
iv

Contents

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

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

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

Description of the Savoy Experimental Watershed........................................................................2

Fluorescent Dye Tracing.............................................................................................................................10

Past Dye Tracing at Langle and Copperhead Springs ..................................................................11

Dye Tracing Conditions During Course ...........................................................................................13

Safety Notes for the Dye Tracing Tests and Future Courses.......................................................13

Point-to-Point Tracer Test at Wow Spring, November 2017 ........................................................13

Quantitative Test at Langle and Copperhead Springs, November–December 2017................16

References Cited..........................................................................................................................................24

Appendix 1. Instructor Profiles GW2227 Advanced Groundwater Field Techniques in 

Karst Terrains Fayetteville, Arkansas, November 13–17, 2017 ...............................................28

Appendix 2. Savoy Experimental Watershed Theses, Dissertations, and Papers ........................37

Appendix 3. Planned Agenda for Advanced Groundwater Field Techniques in

Karst Terrains, GW2227, November 13–17, 2017 .......................................................................39

Figures

1. Location of Savoy Experimental Watershed and six surface watershed

boundaries .....................................................................................................................................3

2. Aerial image of the Savoy Experimental Watershed..............................................................4

3. Annotated photograph of geologic contacts taken from the flood plain looking

east near the Illinois River at Arkansas Highway 16 at the outcrop along the

West University of Arkansas Beef Farm Road, Savoy, Arkansas.........................................5

4. Photograph of Tree Spring, an epikarst spring flowing on top of a chert layer 

forming the headwater of a small stream that picks up flow from a few other 

springs before sinking underground at the Savoy Experimental Watershed,

Arkansas ........................................................................................................................................6

5. Topographic map of basin 1 at Savoy Experimental Watershed, Arkansas.......................7

6. Aerial image of basin 1 at Savoy Experimental Watershed, Arkansas ...............................7

7. Estimated daily precipitation at Savoy, Arkansas, November 1–December 2, 2017 .......10

8. Photographs of a hydrologist setting a bug at Tree Spring at the

Savoy Experimental Watershed, Arkansas............................................................................11

9. Daily mean discharge at Copperhead and Langle Springs, Savoy, Arkansas .................12

10. Normalized RhodamineWT dye and chloride tracer breakthrough curves for

Copperhead and Langle Springs, Savoy, Arkansas, April 13–17, 2001 ..............................12

11. Photograph of fluorescein dye in sinking stream upstream of Wow Spring, 

Savoy Environmental Watershed, Arkansas..........................................................................14

12. Photographs of visual confirmation of fluorescein dye at Wow Springs..........................15

13. Photograph of fluorescein dye in the Illinois River...............................................................15

14. Low-sensitivity spectra interference from background samples at Langle Spring

and Copperhead Spring, Savoy, Arkansas.............................................................................18
v

15. Photographs of RhodamineWT sinking underground at end of the sinking

stream location latitude 36.116772 longitude −94.341883 North American

Datum 1983 and dye injection field crew................................................................................18

16. Low-sensitivity spectra from calibration standards. Linear calibration

equation for converting intensity to concentration for RhodamineWT.............................19

17. Graphs of spectra-fluorometer analyses for grab samples collected at Langle

Spring, Savoy, Arkansas, November 14–15, 2017..................................................................20

18. Images of Langle Spring and Copperhead Spring, November 15, 2017, 

Savoy, Arkansas..........................................................................................................................22

19. Breakthrough curve for RhodamineWT data at Langle Spring, Savoy, Arkansas...........23

20. Linear regressions for calibration of field-fluorometer RhodamineWT

concentration to laboratory estimated grab sample values ...............................................23

Tables

1. Information on some of the springs, miscellaneous discharge measured, and

rhodamineWT dye injection location collected during the class at the Savoy

Experimental Watershed, Basin 1, Savoy, Arkansas..............................................................8

2. Daily precipitation from nearby climate observation stations..............................................9

3. Estimated mass of dye required for 1 part per million..........................................................18

4. Grab sample laboratory analysis at Copperhead and Langle Springs ..............................20

5. Statistics on background rhodamineWT parts per billion readings from the field

fluorometers installed at Langle and Copperhead springs, Savoy, Arkansas..................21

6. Summary of information from the QTRACER2 program .......................................................24
vi

Conversion Factors

U.S. customary units to International System of Units

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2

) 2.590 square kilometer (km2) 

Volume

gallon (gal) 3.785 liter (L) 

cubic foot (ft3

) 28.32 cubic decimeter (dm3) 

cubic foot (ft3

) 0.02832 cubic meter (m3) 

Flow rate

foot per second (ft/s) 0.3048 meter per second (m/s)

foot per minute (ft/min) 0.3048 meter per minute (m/min)

foot per hour (ft/h) 0.3048 meter per hour (m/h) 

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

foot per year (ft/yr) 0.3048 meter per year (m/yr)

cubic foot per second (ft3

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

cubic foot per second per square mile 

([ft3

/s]/mi2)

0.01093 cubic meter per second per square 

kilometer ([m3/s]/km2)

cubic foot per day (ft3

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

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

Mass

pound, avoirdupois (lb) 0.4536 kilogram (kg) 

Density

pound per cubic foot (lb/ft3

) 16.02 kilogram per cubic meter (kg/m3)

pound per cubic foot (lb/ft3

) 0.01602 gram per cubic centimeter (g/cm3)

Hydraulic conductivity

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

Hydraulic gradient

foot per mile (ft/mi) 0.1894 meter per kilometer (m/km)

Transmissivity

foot squared per day (ft2

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

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

 °C = (°F –32) / 1.8.
vii

Datum

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

(NGVD 29).

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

or World Geodetic System 1984 (WGS 84) as noted and in the conterminous United States, for 

all practical purposes the geographic coordinates for WGS84 are equivalent to NAD83 with 

handheld global positioning system units.

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

Supplemental Information

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius 

(μS/cm at 25 °C).

Use of liter (L) as a special name for cubic decimeter (dm3) is restricted to the measurement of 

liquids and gases. No prefix other than milli should be used with liter.

Abbreviations

CST Central Standard Time

nm nanometer

NWIS National Water Information System

PME Precision Measurement Engineering, Inc., Vista, California

ppm parts per million

ppb parts per billion

r

2

 coefficient of determination

RWT RhodamineWT

SEW Savoy Experimental Watershed, University of Arkansas, Savoy, Arkansas

UA University of Arkansas

USGS U.S. Geological Survey

Interpretation of Dye Tracing Data Collected 

November 13–December 2, 2017, at the Savoy Experimental 

Watershed as part of the Advanced Groundwater Field 

Techniques in Karst Terrains Course, Savoy, Arkansas

By Eve L. Kuniansky,1 Joshua M. Blackstock, 2 Daniel M. Wagner, 1 and J. Van Brahana 2

Abstract

The first course on the use of advanced groundwater 

field techniques for karst aquifers was conducted 

November 13–17, 2017, at the University of Arkansas Savoy 

Experimental Watershed (SEW), which is located on pastures 

for beef livestock research conducted by the Department of 

Animal Sciences at the University of Arkansas at Savoy, 

Arkansas. The SEW is an interdisciplinary, collaborative, 

long-term research site for the study of animal-waste 

management in a mantled karst setting. The course focused 

on advanced field activities appropriate for karst aquifer 

studies: dye tracing, groundwater/surface-water interactions, geophysical methods, and geochemistry. This report 

summarizes the data collected and interpreted from the dye 

tracing part of the November 2017 course, other USGS field 

courses, and past dye tracing investigations conducted by 

University of Arkansas students.

Introduction

The first U.S. Geological Survey (USGS) “Advanced 

Groundwater Field Techniques in Karst Terrains GW2227,” 

course was held November 13–17, 2017, in Fayetteville, 

Arkansas, with field data collection at the University of 

Arkansas (UA) Savoy Experimental Watershed (SEW) at 

Savoy, Arkansas. The SEW is an interdisciplinary, collaborative, long-term research site for the study of animal-waste 

management in a mantled karst setting. Planning for this 

first course began in 2014 with meetings in Fayetteville, 

Ark. The final list of instructors, including biographical 

information, is provided in appendix 1. The USGS has 

used the SEW for the course “Introduction to Groundwater 

Field techniques GW1227” twice—April 13–17, 2015, and 

March 6–10, 2017—with a focus on well and spring inventory. 

These two introductory courses provided an opportunity for 

initial reconnaissance and development for the advanced 

course discussed in this report. Additional planning for the 

course leveraged site experience and knowledge gained while 

conducting research at the SEW by several of the USGS 

instructors who received degrees from UA.

The SEW was conceived and developed by UA Department of Geosciences Professor J. Van Brahana as a premier 

water-quality research collaborative beginning in the 1990s. 

In addition to the UA Department of Geosciences, original 

collaborators included the UA Department of Animal Science, 

the USGS office in Fayetteville, Ark., and other UA departments. The SEW is located about 10 miles west of the main 

UA campus in Fayetteville at Savoy, Arkansas. Numerous 

research studies have been conducted at the SEW. Appendix 

2 lists known graduate student research theses, dissertations, 

and papers updated from the list in Brahana (2011), which 

summarizes some of the lessons learned from field research 

at the SEW. Brahana (2011) was published as part of the 

USGS Karst Interest Group Proceedings (Kuniansky, 2011), 

which includes other research from the SEW and the Ozarks 

Plateau aquifer system; the Karst Interest Group workshop 

was hosted by the University of Arkansas Department of 

Geosciences in April 2011.

The main objective of the advanced groundwater 

field techniques course (GW2227) was to introduce USGS 

hydrologists and hydrographers to field methods that can be 

used to understand groundwater flow in karst and fractured 

rock aquifer systems. The course focuses on advanced field 

activities appropriate for karst aquifer studies: dye tracing, 

groundwater/surface-water interactions, geophysical methods, 

and geochemistry. The planned agenda for the course is 

provided as appendix 3. 

1

U.S. Geological Survey.

2

University of Arkansas.
2 Interpretation of Dye Tracing Data Collected at the Savoy Experimental Watershed, Savoy, Arkansas

Purpose and Scope

The purpose of this report is to document the interpretation of the dye tracing data collected during and after the 

“Advanced Groundwater Field Techniques in Karst Terrains 

GW2227” course and provide links to the companion USGS 

data release (Kuniansky, 2019), such that the data and 

interpretation of the data are preserved for planning future 

courses at the SEW. Additionally, guidance for future dye 

tracing investigations is provided. Most of the data were 

collected during the course; however, some dye trace and 

geophysical data collection both preceded the course and 

continued after the course ended. Personnel from the USGS 

Texas Water Science Center conducted reconnaissance for 

surface and borehole geophysical activities and began data 

collection prior to the course. The point-to-point and quantitative dye tracing activities began November 13–15, 2017, 

with preliminary results discussed on November 16 during 

the course; however, the field fluorometers for RhodamineWT (RWT) dye detection were placed at two springs 

to begin logging on November 13 and were left at the site 

until December 2, 2017. The investigation of groundwater/

surface-water interactions included seepage run analysis, 

dye/salt dilution methods, temperature methods, onedimensional heat flux methods with field activities conducted 

during the course; some preparation was conducted on 

Sunday, November 12, and Monday, November 13. All field 

data were collected at the SEW.

Description of the Savoy Experimental 

Watershed

The SEW is located at Savoy, Ark., approximately 

10 miles west-northwest of the main UA campus in the 

city of Fayetteville in northwest Arkansas. The SEW is 

bounded on the north and west by the Ozark National Forest 

and on the south and east by small private farms involved 

in cattle and poultry operations. Six delineated watershed 

basins intersect the 4.82 square-mile (mi2) property of 

the SEW (fig. 1). The basin numbering is from Brahana 

(2011). Only small parts of basins 4, 5, and 6 intersect SEW 

property and basin 3 touches a corner of the SEW. The data 

collection occurred within basin 1. The datasets for the 

quantitative dye trace are available as a USGS data release 

(Kuniansky, 2019).

The SEW is in the southern Ozarks on the Springfield 

Plateau and is underlain by several carbonate-rich strata—

considered a mantled karst terrain. “The karst of the SEW 

is not immediately apparent to most people. The setting is a 

dissected plateau with steep, dry valleys and few sinkholes. 

In most of the area, regolith covers the bedrock, leaving a 

thin, rocky soil that masks the carbonate bedrock beneath. 

The SEW is typical of the Springfield Plateau province of 

the Ozark highlands. Most of the site (>70 %) is covered in 

second- and third-growth forests, and the remaining land 

is in pasture” (Brahana, 2011) as can be seen in the aerial 

image in figure 2. 

The SEW has pastures for beef livestock of the UA 

Department of Animal Science (approximately 30 percent 

of the area, mostly in surface watershed basins 1 and 6, 

see figures 1 and 2). The terrain is somewhat hilly. The 

upland altitude is about 1,220 feet (ft) at ridges, and the 

Illinois River flood-plain altitude is about 1,020 ft (National 

Geodetic Vertical Datum of 1929 [NGVD 29]). Thus, there 

is an approximate 200-ft range in altitude from ridges to 

the Illinois River. Weathered-in-place regolith overlies the 

original carbonate rocks and the regolith varies in thickness 

from 0 to approximately 10 ft. Regolith is a region of 

loose unconsolidated rock and dust that sits atop a layer of 

bedrock. The soil and regolith layers at land surface help 

store infiltrated rainwater, which is slowly released to the 

epikarst and base-level springs.

The karst groundwater system at the SEW is composed 

of a chert-rich carbonate-rock sequence that has been 

selectively dissolved to form an open network of caves, 

enlarged fractures, bedding planes, conduits, sinking streams, 

and springs. Groundwater flow within wider aperture 

conduits typically is rapid with flow directions difficult 

to predict, interaction between surface and groundwater 

typically extensive, and contaminant attenuation processes 

inherent within porous media groundwater systems absent 

(White, 1988; Ford and Williams, 2007; Palmer, 2007; 

Brahana, 2011). 

The relatively flat-lying formations of the Springfield 

Plateau have been affected by reactivated basement faulting 

associated with the Ouachita orogeny during early Mississippian time (Brahana, 2011). The stratigraphy at the SEW from 

top to bottom is as follows: soil and weathered carbonates 

that form a mantle of regolith or epikarst, Boone Limestone, 

St. Joe Limestone (the Boone Limestone and St. Joe 

Limestone are considered members of the Boone Formation 

by the Arkansas Geological Survey), and Chattanooga Shale, 

which is incised by quaternary alluvium along the Illinois 

River flood plain. The Boone Formation (Boone and St. Joe 

limestones) are Mississippian in age and the Chattanooga 

Shale is Devonian in age. A photograph taken from the flood 

plain 0.5 miles south of SEW facing east from the flood 

plain east of the Illinois River north of Highway 16 with 

farm road 845 (also called West University of Arkansas Beef 

Farm Road) at the base of the bluff shows formation or rock 

contacts delineated by J. Van Brahana (fig. 3, location of 

where photo taken shown on fig. 1). Over time, weathering 

has created fractures within these formations, creating the 

mantle-karst properties at the site. The St. Joe Limestone 

member of the Boone Formation is a fine-grained, crinoidal 

limestone that contains chert beds (Chandler, 2001). At the 

SEW, the upper Boone Limestone ranges in thickness from 

0 (where eroded) to 30+ ft thick, and the St. Joe Limestone 

ranges from 0 where eroded and missing in the flood plain 

to 20± ft thick, with the Chattanooga Shale being more 

than 50 ft thick.
Introduction 3

res19_hwca00_0012_fig01

Savoy

Springdale

climate station

Farmington

climate station

Viney Grove

climate station

Wow

Spring

Langle

Spring

Copperhead

Spring

5

2

6

3

4

1

OZARK

NATIONAL

FOREST

Illinois Rive r

WC 845

16

68 68

6

BENTON

WASHINGTON

Base from U.S. Geological Survey metric topographic map Fayetteville, Arkansas/ 0

Oklahoma, and Missouri 1979, 1:100,000-scale

Projection and 10,000-meter grid, zone 15, Universal Transverse Mercator

2 MILES

0 3 KILOMETERS

1

1.5

EXPLANATION

Savoy Experimental

Watershed boundary

Approximate area for

figures 5 and 6

Surface watershed boundary

and basin number

Climate station

Spring

Location photo taken for

figure 3

Latitude/Longitude tic for

U.S. Geological Survey

Wheeler Quadrangle

Arkansas 7.5 minute

topographic map series

N

Figure 1. Location of Savoy Experimental Watershed and six surface watershed boundaries (modified from Brahana, 2011).

Chert within the Boone Formation is insoluble; 

however, limestone when exposed to rainwater over time 

dissolves, and miniature caves (that is, solution channels) 

form within the limestone. In turn, water flows laterally 

across chert until it moves downward through a vertical 

fracture or reaches an outlet at an exposure of the formation 

at land surface. There is some speculation that linear stream 

segments formed along joint or graben structures where 

rainwater more easily moved into the rocks and dissolved 

the limestone (Brahana, 2011). Mechanical and chemical 

dissolution processes facilitate chert gravel formation within 

the epikarst and within streams that incise the Boone and St. 

Joe Limestones with many of the epikarst springs issuing from 

the top of slightly dipping chert planes (fig. 4).
4 Interpretation of Dye Tracing Data Collected at the Savoy Experimental Watershed, Savoy, Arkansas

res19_hwca00_0012_fig02

Savoy Experimental Watershed boundary

Pasture

Forest

0 1

0 1

2 MILES

2 KILOMETERS

Base from base-map projection

Universal Transverse Mercator Zone 15S

N

Figure 2. Aerial image of the Savoy Experimental Watershed (SEW) (modified from J. Van Brahana, 

November 2017 class presentation).

The Illinois River graben forms the western boundary of 

watershed basin 1 along the Illinois River at the SEW (fig. 1). 

A fault along the graben was identified by displacement of the 

St. Joe-Chattanooga contact, an escarpment, and the appearance of springs along the escarpment base during wetter than 

average rainfall, and a zone of low permeability. Geophysical 

studies, field reconnaissance, and surveying helped map the 

top of the Chattanooga Shale and other structures at the SEW 

(Stanton, 1993; Unger, 2004). Observations indicate that the 

fault along the Illinois River graben serves as a groundwater 

dam, which focuses groundwater discharging to Langle and 

Copperhead Springs (fig. 1). 

Several springs at the SEW have permanent weirs in 

place that have been gaged at varying times in the past. 

Langle and Copperhead Springs formed at the contact between 

the Boone Limestone and the underlying St. Joe Limestone 

and are the base-level springs in the surface watershed basin 

1 boundary (fig. 1). Discharge from Langle and Copperhead 

Springs flows to the Illinois River. The Illinois River flood 

plain overlies the Chattanooga Shale, which prevents 

immediate infiltration of surface water to the underlying 

aquifers (Hamilton, 2001). 

Numerous small epikarst springs issue from the top of 

slightly dipping chert planes within the upland areas at the 

SEW (fig. 4). The topographic map of part of basin 1 at the 

SEW (fig. 5) reflects the inferred dip of chert beds. In addition 

to the almost north-south Illinois River graben, the incised 

stream valley approximately perpendicular to the Illinois River 

graben may have been formed along another graben because 

there is a slight difference in the dip direction of the chert beds 

north of this intermittent and sinking stream from beds to the 

south of the stream.

 During the field methods course held at the SEW during 

March 2017, the incised stream valley (labeled “Graben 

along incised valley???” in figs. 5 and 6) was mostly dry and 

was completely dry at the dirt road just north of Tree Spring. 

In fact, any flow in the valley segment north of Tree Spring 

and the road had sunk underground. According to course 
Introduction 5

Figure 3. Annotated photograph of geologic contacts taken from the flood plain looking east near the Illinois River

at Arkansas Highway 16 at the outcrop along the West University of Arkansas Beef Farm Road (labeled WC Rd 845, 

fig. 1), Savoy, Arkansas (photograph by J. Van Brahana, February 25, 2012).

instructors that have done research at the site over many years, 

the intermittent stream shown on the topographic map flows 

as one stream only during flood events. Tree Spring, as well 

as the other epikarst springs upslope from the incised valley, 

generates a small stream that flows to the west, downslope in 

watershed basin 1. (See the aerial image in fig. 6 from early 

2018 of approximately the same area as the topographic map 

in fig. 5.) This small stream from the epikarst springs near Tree 

Spring completely sank into the ground at the location where 

the RWT dye was injected for the quantitative dye tracing part 

of the course (figs. 5 and 6).

Perched groundwater that moves laterally and discharges 

to small springs and then sinks underground is typical of 

epikarst springs in northwest Arkansas. Several course 

activities took place near these epikarst springs: discharge 

measurements using salt dilution were made, temperature 

methods for calculating discharge were demonstrated, and 

volumetric discharge measurements were made (Kurylyk and 

others, 2017; Rantz, S.E., 1982). Table 1 provides information 

about these named springs from signs posted at the SEW; 

latitude and longitude data, in North American Datum of 

1983, and altitude data, in feet NGVD 29, were retrieved 

from the USGS National Water Information System (NWIS; 

https:waterdata.usgs.gov/nwis, accessed, October 29, 2014, 

to retrieve site information for wells and springs within SEW 

for earlier training classes) or were gathered by handheld 

Global Positioning System and are included if available. The 

altitudes of the springs, in meters above mean sea level, as 

posted on signs at the site were assumed to be accurate but 

were not an exact match when converted to feet and compared 

to the altitudes in NWIS; it is not known which altitude is more 

accurate.

The climate in the area is considered humid continental. 

Average annual precipitation in Fayetteville, Arkansas, is 

45 inches. Winters are short and mild with brief periods of 

snow cover and frost with a mean January low of 26 degrees 

Fahrenheit (°F) and average snowfall of 2 inches. Summers 

are long, warm, and humid with a mean July and August high 

temperature of 89 °F. Rainfall occurs throughout the year 

with monthly average rainfall ranging from 2 to 5 inches and 

monthly rainfall greater than or equal to 4.5 inches in May 

and June and less than 3 inches in January and February 

(U.S. climate data, 2018a).

Daily precipitation at SEW from November 1 through 

December 2, 2017, was estimated by averaging daily rainfall 

data, when available, from one to three nearby weather stations 

(table 2, locations shown on fig. 1). As shown in table 2, it was 

dry during the 12 days preceding, during, and immediately after 

the field methods course. Total precipitation was estimated to 

be 1.42 inches for the month of November with the majority 

falling during the last 2 days of November and no precipitation 

the first 2 days of December (fig. 7). Daily temperatures in 

Fayetteville were mild with lows ranging from 34 to 51 o

F and 

highs from 54 to 70 oF during the course (U.S. climate data, 

2018b). Daylight hours were short; thus, evapotranspiration was 

assumed to be zero during the course. 
6 Interpretation of Dye Tracing Data Collected at the Savoy Experimental Watershed, Savoy, Arkansas

Figure 4. Photograph of Tree Spring (see figs. 5 and 6 for location), an epikarst spring flowing on top 

of a chert layer forming the headwater of a small stream that picks up flow from a few other springs 

before sinking underground at the Savoy Experimental Watershed, Arkansas (photograph provided by 

Cassi Crow, November 2017, taken looking to the southeast).
Introduction 7

res19_hwca00_0012_fig05

Base from U.S. Geological Survey topographic map

Polyconic projection

1927 North American Datum

Contour interval 20 feet

National Geodetic Vertical Datum of 1929 

0 1,000 2,000 FEET

0 250 500 METERS

Figure 5. Topographic map of basin 1 at Savoy Experimental Watershed, Arkansas (modified from 

J. Van Brahana training materials, November 13, 2017).

res19_hwca00_0012_fig06

Illinois River

Wow Spring

Langle Spring

Copperhead Spring

Tree Spring

Woodpecker

Spring

RhodamineWT

injection

Fluorescein

injection

Dip of

Basal Chert

Dip of

Basal Chert

Graben along incised valley?? Red

Dog 

Spring

Unnamed

Springs

Illinois River Graben

0 200 FEET

0 60 METERS

N

Figure 6. Aerial image of basin 1 at Savoy Experimental Watershed, Arkansas (modified from Google 

maps, April 21, 2018).
8 Interpretation of Dye Tracing Data Collected at the Savoy Experimental Watershed, Savoy, Arkansas Table 1. Information on some of the springs, miscellaneous discharge measured, and rhodamineWT dye injection location collected during the class at the Savoy Experimental Watershed, Basin 1, Savoy, Arkansas. [GPS, Global Positioning System; latitude in decimal degrees; n.d. (no data), indicates that a data observation was not reported; NAD83; longitude in decimal degrees NAD83; L/s, liters per second; NGVD29, National Geodetic Vertical Datum of 1929; NWIS, National Water Information System; USGS, U.S. Geological Survey] Name USGS Site ID 1latitude 1longitude Description Altitude (m) NGVD29 Typical discharge low (L/s) Typical discharge high (L/s) Discharge during class November 13–15, 2018 (L/s) Comment Base springs in Basin 1 n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. Langle Spring 71948218 36.118969 −94.345489 Underflow spring, St. Joe Formation 314.32 0.85 89.5 2.9 From rating curve Copperhead Spring 71948215 36.114802 −94.345211 Overflow spring, St.Joe Formation 314.39 0.293 379 0.4 Volumetric measurement Epikarst Springs in Basin 1 and locations of discharge from salt dilution and temperature parts of class Tree Spring n.d. 36.116915 −94.339859 Epikarst of the Lower Boone Formation 328.22 0.09 0.62 0.23 Volumetric measurement Discharge measured in stream downstream of Tree, but upstream of Woodpecker n.d. n.d. n.d. n.d. n.d. n.d. n.d. 0.32 From salt dilution Woodpecker Spring n.d. 36.116983 −94.340355 Epikarst of the Lower Boone Formation 325.63 0.05 0.38 0.062 From salt dilution No sign on fence spring more to the east between Woodpecker and Red Dog n.d. 36.116836 −94.340628 Epikarst of the Lower Boone Formation n.d. n.d. n.d. Very small trickle Visual observation No sign on fence spring more to the west between Woodpecker and Red Dog n.d. 36.116822 −94.340762 Epikarst of the Lower Boone Formation n.d. n.d. n.d. Very small trickle Visual observation Red Dog Spring n.d. 36.116784 −94.340854 Epikarst of the Lower Boone Formation 324.29 0.06 0.48 0.096 From salt dilution Discharge measured in stream downstream of Red Dog but before stream begins to lose flow to karst n.d. n.d. n.d. n.d. n.d. n.d. n.d. 0.64 From salt dilution Discharge measured in stream right before all goes into sink 

where dye was injected

n.d. n.d. n.d. n.d. n.d. n.d. n.d. 0.35 From salt 

dilution

Location of RhodamineWT dye 

injection

n.d. 36.116813 −94.341281 n.d. n.d. n.d. n.d. n.d. n.d.

Point to Point Tracer Test Spring n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d.Wow Spring n.d. 36.121810 −94.343023 n.d. n.d. n.d. n.d. Very small trickle Visual 

observation

1Latitude and longitude data for Langle and Coppperhead Springs from NWIS (North American Datum 1983 [NAD83]) all the other spring locations from Joshua Blackstock GPS unit reporting 

maximum location error 16 feet (World Geodetic System 1984, which for practical purposes is the same as NAD83 in the conterminous United States). 
Introduction 9

Table 2. Daily precipitation from nearby climate observation stations near the Savoy Experimental Watershed, Arkansas, 

November−December 2, 2017.1

[in., inches; T, values in the precipitation or snow category indicate a “trace” value was recorded; n.d. (no data), indicates that a data 

observation was not reported; pink shade is quantitative tracer test period of data collection]

DATE

Station: Farmington 0.6 WSW, 

AR US US1ARWS0025 

current location: elev: 1205 ft. 

lat: 36.0378° N

long: −94.2507° W (in.)

Station: Springdale 6.4 WSW, 

AR US US1ARWS0032 current 

location: elev: 1270 ft.

lat: 36.1584° N

long: −94.2571° W (in.)

Station: Viney Grove 2.4 NW, 

AR US US1ARWS0022 current

location: elev: 1193 ft. 

lat: 36.0449° N

long: −94.3576° W (in.)

Average 

precipitation 

(in.)

11/1/2017 0.05 T 0.02 0.04

11/2/2017 0.01 0 0 0.01

11/3/2017 n.d. 0 0 0.00

11/4/2017 n.d. 0 0 0.00

11/5/2017 n.d. 0 0 0.00

11/6/2017 n.d. 0 0 0.00

11/7/2017 0.1 0.17 0.11 0.13

11/8/2017 0.06 0.02 0.02 0.03

11/9/2017 n.d. 0 0 0.00

11/10/2017 n.d. 0 0 0.00

11/11/2017 n.d. 0 0 0.00

11/12/2017 n.d. 0 0 0.00

11/13/2017 n.d. 0 0 0.00

11/14/2017 0.04 T 0.02 0.03

11/15/2017 0.25 0.3 0.12 0.22

11/16/2017 0.03 n.d. 0 0.02

11/17/2017 n.d. n.d. 0 0.00

11/18/2017 n.d. n.d. 0 0.00

11/19/2017 n.d. n.d. 0 0.00

11/20/2017 n.d. n.d. 0 0.00

11/21/2017 n.d. n.d. 0 0.00

11/22/2017 n.d. n.d. 0 0.00

11/23/2017 n.d. n.d. 0 0.00

11/24/2017 n.d. n.d. 0 0.00

11/25/2017 n.d. n.d. 0 0.00

11/26/2017 n.d. n.d. 0 0.00

11/27/2017 n.d. n.d. 0 0.00

11/28/2017 n.d. n.d. 0 0.00

11/29/2017 0.25 0.59 0.98 0.61

11/30/2017 0.22 1.3 0.1 0.54

12/1/2017 n.d. 0 0 0.00

12/2/2017 n.d. 0 0 0.00

Total during period 1.42

1

Data are from the U.S. Department of Commerce, National Centers for Environmental Information, obtained April 11, 2018.
10 Interpretation of Dye Tracing Data Collected at the Savoy Experimental Watershed, Savoy, Arkansas

res19_hwca00_0012_fig07

0

0.10

0.20

0.30

0.40

0.50

0.60

0.70

Daily precipitation, in inches

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

November

2017

December

16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 1 2

Figure 7. Estimated daily precipitation at Savoy, Arkansas, November 1–December 2, 2017.

Fluorescent Dye Tracing

Two types of dye trace field experiments were conducted 

as part of the groundwater field methods course: point-to-point 

and quantitative dye traces. Numerous dye traces have been 

conducted at the SEW (Brahana, 2011); however, previous 

dye traces were not conducted under the dry conditions and 

low flows observed at both Langle and Copperhead Springs 

during this course. To prevent dye interference between the 

point-to-point and quantitative dye, the quantitative test was 

conducted using RWT (red dye fluorescence peak around 

575 nanometers) in basin 1 that was known to flow toward 

Langle and Copperhead Springs, and the point-to-point test 

was conducted using fluorescein (green dye fluorescence peak 

around 510 nanometers) in a different spring subbasin of basin 

1 that flows toward Wow Spring (altitude is slightly higher 

than Copperhead Spring and Langle Spring based on estimation from the topographic map; fig 5). In this way, if both dyes 

show up at any of the springs, the injection location will be 

confirmed. If only one dye is used or two dyes with a similar 

fluorescence peaks at two injection locations, it would be 

uncertain of the source of the dye emerging from any spring.

For many epikarst dye traces, it is necessary to use a tanker 

of water to flush the dye into the unsaturated zone, particularly 

if rainfall during the study period is minimal. If a sinking 

stream is present, however, there may be no need to supply 

additional flushing water. Moreover, the introduction of large 

flushing volumes of water may induce groundwater flow paths 

that are uncharacteristic of the groundwater system even during 

high-flow events. Although the SEW is in an epikarst area, there 

were sinking streams upgradient from known discharge springs 

and thus no tanker or flushing water was required. In general, if 

flushing water is required, deionized water should be used.

Point-to-point tracer tests at the SEW were generally 

conducted to determine if a sink was connected to a specific 

outlet location (such as a well, spring, or cave). Hydraulic 

connections can be verified with visual confirmation or 

through the deployment of “bugs,” which are dye-absorbent 

material, typically activated carbon, in a flow-through mesh 

bag that is anchored in the well, stream, or spring (fig. 8). If 

used, the bugs absorb the dye and can be deployed for days or 

months before retrieval and analysis. These qualitative tests 

are commonly used and are almost always performed before a 

quantitative tracer test is conducted. In practice, point-to-point 

tests determine which sinks are connected to which outlets but 

are often conducted over long periods whereby the exact time 

it takes for the dye to move through a system cannot be the 

primary objective. If bugs are retrieved and replaced with new 

bugs sub-daily, daily, or at weekly intervals, the approximate 

number of days or weeks for the dye to reach the outlet can 

be estimated. If activated carbon bugs are used in a qualitative 

point-to-point test, a laboratory spectra-fluorometer can be 

used with the elutant from the bugs (an elutant liquid is used 

to remove dye from the activated carbon bugs). Although 

the instructors brought bugs for the dye trace and had these 

anchored at several springs, the bugs were for demonstration 

purposes and were not analyzed. 

Quantitative tests can provide detailed information 

regarding hydraulic properties (hydraulic conductivity, 

contaminant travel time) for a karst aquifer, but are far 

less commonly conducted than point-to-point tracer tests. 

Quantitative tests require information on the amount of dye 

injected and the time series of concentration and groundwater 

discharge (spring flow or well discharge rates and concentration). With fluorescent dye tracers, a field fluorometer and 

data logger typically are calibrated with standards in the 
Fluorescent Dye Tracing 11

field according to the manufacturer’s instructions, and the 

equipment is installed at the discharge location. Grab samples, 

however, are collected frequently, and a laboratory spectrafluorometer is calibrated with standards and the grab samples 

are analyzed in the laboratory. It is always advisable to collect 

and analyze grab samples even when a field fluorometer/data 

logger is deployed. 

References for conducting dye tracing in karst include 

Mull and others (1988a), Aley (2002), Field (2002, 2003), 

Worthington and Smart (2003), and Goldscheider and others 

(2008). Some USGS reports that include tracer testing are 

Mull and others (1988b), Mull (1993a, 1993b), Robinson 

(1995), Bayless and others (1994), Taylor (1997), Kidd and 

others (2001), Spangler and Susong (2006), Kozar and others 

(2007), Long and others (2012), and Spangler (2012).

Past Dye Tracing at Langle and 

Copperhead Springs

Past dye tracing and flow monitoring at Langle and 

Copperhead Springs under various hydrologic conditions 

have shown that the spring-basin size is related to groundwater levels in basin 1 (Brahana, 2011). Both Langle and 

Copperhead Springs are base-level underflow springs in 

basin 1; however, Langle is the lowermost underflow spring 

with the spring outlet being approximately an inch lower 

than Copperhead. During storm events, Copperhead Spring 

typically flows at a greater discharge rate than Langle Spring, 

indicating that the dissolution openings feeding Copperhead 

are larger than those feeding Langle. In addition, more 

water can be transmitted to Copperhead Spring at higher 

groundwater-level conditions; however, Langle Spring 

maintains greater flow during dry conditions (fig. 9). During 

the course, both springs flowed at almost a constant rate. 

Figure 8. Photographs of a hydrologist setting a bug (dye-absorbent material in a flow-through mesh bag) at 

Tree Spring at the Savoy Experimental Watershed, Arkansas (photograph by Eve Kuniansky, November 12, 2018).

Volumetric measurements were made at both springs, using 

a stopwatch and a 2-liter (L) graduated cylinder. Flow at 

Copperhead Spring remained constant at 0.4 liter per second 

(L/s; 0.01 cubic foot per second [ft3/s]). The standard deviation 

from multiple teams conducting volumetric measurements 

during the course was 0.01 L/s (0.0004 ft3/s). During the 

course, the instructor demonstrated how to use the acoustic 

flow instrumentation and monitored the stage behind the weir 

at Langle Spring. This monitoring indicated a constant flow 

of 2.9 L/s (0.1 ft3/s) or 10 times the low flow of Copperhead 

Spring. Langle Spring has not been observed to go dry 

historically, but Copperhead Spring was observed to be dry 

for a few days in the late summer of 1998 (fig. 9). Although 

there are only 2 years of flow data available in NWIS for 

these two springs, the flow during the course was similar to 

the lowest observed flow for 1997–98 at both springs (NWIS; 

https://waterdata.usgs.gov/nwis accessed April 17, 2018, to 

retrieve this flow data).

A previous dye tracing study at the SEW in April of 

2001 was conducted at high discharges and groundwater 

levels using RWT dye and salt (chloride measured). RWT 

was poured into the sinking stream at approximately the same 

injection site as used in the November 2017 course (fig. 5). 

In the 2001 study, the first appearance of dye after injection 

occurred in 16.5 hours for Langle Spring and 11.5 hours for 

Copperhead Spring; the peaks occurred at 24.5 hours for 

Langle Spring and 16.5 for Copperhead Spring (fig. 10). As 

shown in figure 10, the chloride peaks occurred sooner than 

the RWT peaks (3 hours sooner at Langle Spring and 1 hour 

sooner at Copperhead Spring). The much longer tail on the 

dye-normalized curve compared to the chloride-normalized 

curve indicates some adsorption and desorption of dye 

in the system. (Each curve is normalized by dividing the 

concentration for each curve by the peak concentration of that 

constituent, allowing all curves to plot on a zero to 1 y-axis.)
12 Interpretation of Dye Tracing Data Collected at the Savoy Experimental Watershed, Savoy, Arkansas

res19hwca000012fig09

0.01

0.1

1

10

Daily mean discharge, incubic feet per second

Copperhead Spring

Langle Spring

Aug. 19 Nov. 19 Dec. 19 Jan. 19

1997 1998

Sept. 19 Oct. 19 Feb. 19 Mar. 19 Apr. 19 May 19 June 19 July 19 Aug. 19 Sept. 19 Oct. 19 Nov. 19 Dec. 19

EXPLANATION

Missing daily

discharge data

Figure 9. Daily mean discharge at Copperhead and Langle Springs, Savoy, Arkansas (data are from the 

U.S. Geological Survey National Water Information System).

Copperhead Spring dye

Copperhead Spring chloride

Langle Spring dye

Langle Spring chloride

EXPLANATION

Results

Copperhead Spring

 First appearence after injection:

 11.5 hours

 Peak: Chloride at 15.5 hours,

 Rhodamine 16.5 hours

 (48.3 micrograms per liter; a

 dilution of 3.2 × 10 –7)

Langle Springs

 First appearence after injection:

 16.5 hours

 Peak: Chloride at 21.5 hours,

 Rhodamine 24.5 hours

 (76.7 micrograms per liter; a

 dilution of 5.07 × 10 –7)

1.0

0.8

0.9

0.7

0.5

0.6

0.4

0.2

0.3

0.1

0

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Normalized tracer value, dimensionless

Elapsed time in days from noon, April 13, 2001

Figure 10. Normalized RhodamineWT dye and chloride tracer breakthrough curves for Copperhead and Langle Springs, 

Savoy, Arkansas, April 13–17, 2001 (modified from image provided by J.V. Brahana, November 13, 2017).
Fluorescent Dye Tracing 13

Dye Tracing Conditions During Course

Discharge from the small epikarst springs at the SEW that 

included Tree Spring and springs west of Tree Spring forms 

a small stream that sinks underground updip/upgradient from 

both the Copperhead and Langle Springs discharge points 

(fig. 6). For the class quantitative test, RWT dye tracer was 

poured at the sink point at the end of this small stream the night 

before grab samples were collected. Before and during the 

course,volumetric measurements were made at Tree Spring, 

and salt-dilution methods (Rantz and others, 1982) were used 

to measure discharge during the course at Woodpecker Spring, 

Red Dog Spring, and unnamed springs (table 1). The sum of 

the flows from these epikarst springs, as well as the estimated 

flow rate at the sink point, was about 0.4 L/s. The natural 

spring discharge stream that sinks upgradient from Langle and 

Copperhead Springs was deemed adequate to flush the dye into 

the system as opposed to using a tank of deionized water. 

A similar sinking stream situation was needed for a 

successful point-to-point test with visual confirmation. Fortunately, the instructors knew of another spring (Wow Spring, 

fig. 6) with an upgradient sinking epikarst stream in the 

sub-watershed just north of Langle Spring. Fluorescein dye 

(green) was selected for the point to point test at Wow Spring, 

such that RWT dye (red) could be used for the quantitative test 

at a different injection location. From experience, Dr. Brahana 

suggested that we pour the dye for both dye tracing tests 

on Monday night, November 13, 2017, between 10 and 

11:00 p.m., which was the night before the field day, hoping the 

dye would be visible some time the next day (Tuesday). 

Because the dye trace experiment was part of a training 

course and the dye needed to be poured at night, we discouraged course attendees from being present to observe the dye 

injection. By limiting student exposure during the dye injection, 

contamination was essentially eliminated during subsequent 

grab sampling by student attendees. Only one course attendee 

accompanied four instructors to assist in the dye pouring and 

aided in locating the sinking stream section for Wow Spring. 

Safety Notes for the Dye Tracing Tests and 

Future Courses

Locating the sinking stream that emerges at Wow Spring 

involved patience with the resident cows as well as walking 

through the woods in the dark along a steep hillside to find the 

stream section, all while hauling two large containers of mixed 

fluorescein dye. The assistance of Jason, Dan, and Joshua was 

greatly appreciated by the older members of the team (Van 

and Eve) who feared falling on the sharp chert nodules in the 

dark. We recommend keeping this safety issue in mind for 

future courses because the chert nodules are very sharp and 

can easily cut through clothing or cause injury if one falls on 

them. Additionally, if anyone stays to collect grab samples 

the following day and night, be aware that a camp fire on 

top of chert, or within a chert rock enclosure, could also be 

dangerous because entrapped air within the chert can cause 

these rocks to explode when heated. Another safety concern 

is poison ivy, which is abundant at the site. Individuals 

involved in walking through the woods to locate the sinking 

stream upgradient from Wow Spring should be careful not 

to grab vines if they are allergic to poison ivy. This course 

was conducted in relatively cold weather, so no snakes were 

observed; however, during the spring and summer, poisonous 

snakes may be on the property. If preclass time permits, the 

sinking epikarst stream upgradient from Wow Spring could be 

located during the day and a path cleared to the pasture area. 

Wow Spring itself is easily accessible for visual confirmation 

of dye. The sinking epikarst stream upgradient from Copperhead Spring and Langle Spring is easily accessible as are other 

springs described in table 1.

 Additionally, arrangements were made preclass with the 

UA cattle breeding farm to remove the cattle from the area 

near Copperhead and Langle Springs as a safety precaution; 

however, cattle were in the fields at the entrance to the SEW 

and in the subbasin with Wow Springs. It is critical to remind 

students to close all fence gates during the class so that cattle 

do not move out of fenced areas because livestock breeding 

research is ongoing at the SEW.

Point-to-Point Tracer Test at Wow Spring, 

November 2017

Two large containers of mixed fluorescein dye (2 pounds 

[lbs] in each 2-gallon jug) were obtained by Dr. Brahana for 

use in previously planned tracer tests at the SEW, but the dye 

was not used and needed to be discarded. This large amount 

of dye was not necessary for the short point-to-point tracer 

distance between the sink and Wow Spring (approximately 

1,100 ft or 0.2 mile). In retrospect, about a half pound of dye 

would have been enough; however, Dr. Brahana wanted to 

dispose of the dye that he had on hand and he was certain that 

no harm would be done in using that amount of dye because 

no drinking-water intakes are within miles downstream of the 

SEW on the Illinois River, which is where all the dye would 

eventually discharge. After finding the sinking stream, Joshua 

and Dan poured a total of 4 lbs of fluorescein dye into the 

sinking stream upgradient from Wow Spring at the injection 

location recorded in field notes (latitude 36.1211222, longitude 

−94.33930555, World Geodetic System 1984 datum with 

an accuracy of plus or minus 20 ft; the fluorescein injection 

and sink in figs. 5 and 6) on Monday, November 13, 2017, at 

2211 CST (fig. 11).

Dye was observed coming out of Wow Spring some 

time prior to 1400 on Tuesday, November 14, 2017, less than 

16 hours after injection of the dye, and had made it half way 

to the Illinois River by that time (fig. 12). Because more than 

enough dye was injected, the concentration was too high for 

a field fluorometer to detect; however, the high concentration 

was ideal for visual confirmation because there would be 

no doubt if dye was present (fig. 12). By November 15, 

fluorescein dye was in the Illinois River (fig. 13).
14 Interpretation of Dye Tracing Data Collected at the Savoy Experimental Watershed, Savoy, Arkansas

Figure 11. Photograph of fluorescein dye in sinking stream upstream of Wow Spring, Savoy Environmental 

Watershed, Arkansas (photograph by Eve Kuniansky, Monday, November 13, 2017, at 2215 Central Standard Time).
Fluorescent Dye Tracing 15

res19_hwca00_0012_fig12

Wow Spring

Downstream view

Figure 12. Photographs of visual confirmation of fluorescein dye at Wow Springs (photograph by 

Eve Kuniansky, Tuesday, November 14, 2017, at 1430 Central Standard Time).

Figure 13. Photograph of fluorescein dye in the Illinois River (photograph by Cassie Crow, Wednesday, November 15, 2017, at 

1346 Central Standard Time).
16 Interpretation of Dye Tracing Data Collected at the Savoy Experimental Watershed, Savoy, Arkansas

Quantitative Test at Langle and Copperhead 

Springs, November–December 2017

For successful quantitative tests it is critical to (1) consult 

local geology experts in selecting injection and discharge 

location(s), (2) collect background samples of water to 

determine if there is any background fluorescence that may 

interfere with the test, (3) select the dye that is appropriate 

for the hydrogeologic setting, (4) use regression equations, 

once the appropriate dye is selected, to estimate the amount 

of dye required (Field, 2003; Worthington and Smart, 2003), 

(5) run point-to-point tests to confirm the link(s) from the 

sink(s) to the discharge location(s), (6) determine which method 

of collecting the time series of discharge and concentration (or 

fluorescence) data will be used, (7) determine the thickness of 

the unsaturated zone and whether or not a tanker of deionized 

water is required to flush dye into the karst system, (8) determine if a pulse of dye will be used or if a continuously injected 

concentration will be used, and (9) use dark sample bottles, 

or have a dark place to store the grab samples, because many 

organic dyes will lose fluorescence if exposed to sunlight. 

As stated previously, numerous point-to-point and 

quantitative dye tracer studies have been conducted at higher 

groundwater levels and springflow discharge rates at the 

SEW site. The location of the quantitative test at Langle and 

Copperhead Springs was chosen based on these past tracer 

tests. RhodamineWT (RWT) was the organic dye used for 

the quantitative test. Two continuous RWT fluorometer/data 

loggers were borrowed from UA for this test. The two field 

fluorometers/loggers were Precision Measurement Engineering, 

Inc. (PME) data loggers, using a Turner Design Submersible 

Cyclops-7 RWT fluorometer (PME, Inc., Vista, California, and 

Turner Design, San Jose, California). RWT has a fluorescence 

wavelength peak at 575 nanometers (nm) and is one of the 

most common harmless organic dyes used for tracer tests. 

Because RWT is an organic chemical, however, it adsorbs to 

organic material and thus is not totally conservative in terms 

of its transport properties. Although the point-to-point test at 

Wow Spring was conducted in a different subbasin of basin 1, 

fluorescein was used for that test. Fluorescein is an organic dye 

that has a wavelength peak at 510 nm and therefore, even if 

this dye made it to Langle or Copperhead Springs, it should not 

interfere with the RWT peak.

Field fluorometers do not measure a spectrum of 

wavelength as does a laboratory spectra-fluorometer. Most 

field fluorometers are used to detect a range of voltage/concentration for a specified range of wavelength. Therefore, it is 

important to try to estimate the amount of dye to use, such that 

the range of detection of the field fluorometer is not exceeded. 

The Cyclops-7 fluorometer is designed to detect fluorescence 

from chlorophyll a, cyanobacteria, and RWT tracer dye. The 

device has two light-emitting diode (LED) sources that act 

as the excitation light source and can measure fluorescence 

of RWT from 0.01 to 1,000 parts per billion (ppb) (http://

www.turnerdesigns.com/products/submersible-fluorometer/

cyclops-7f-submersible-fluorescence-and-turbidity-sensors). 

The laboratory spectra-fluorometer at UA was a Shimadzu 

RF-5301PC and was set up by Joshua Blackstock to record 

spectra from 540 to 680 nm (the full range for RWT). The 

Shimadzu fluorometer was used to analyze a small volume of 

liquid sample in a proprietary vial. The device allowed for two 

different sensitivity settings—high and low—for recording a 

full visible spectra intensity of fluorescence. These instruments 

were calibrated using a set of standards for the RWT dye 

created in the UA laboratory from the purchased RWT dye. 

Background samples analyzed using the Shimadzu 

fluorometer indicated some interference with RWT in the range 

of 554 to 566 nm. The SEW is in an agricultural area and, 

according to Aley (2002), agricultural chemicals can interfere 

with RWT. Additionally, many dye traces have been conducted 

at this same location, thus degraded organic dye may be present. 

Most of the other common sources of interference mentioned 

by Aley (2002) are unlikely for the SEW because it is not in 

an urban or industrial area. Funding was not available for full 

water-quality analysis of the background spring discharge. Thus, 

the background interference source is unknown. The background low-sensitivity spectra at Langle Spring and Copperhead 

Spring is shown in figure 14. Note that these background grab 

samples were collected post-dye injection, but well before any 

dye was present because previous sample spectra were not 

kept. It should be noted that the recorded intensity is a relative 

reading. A slightly higher background interference intensity 

value was recorded at Langle Spring than at Copperhead Spring 

(fig. 14). The peak background intensity was 559 nm at Langle 

Spring and 560 nm at Copperhead Spring, below the 575 nm 

peak for RWT (fig. 14).

For the quantitative tracer test, we wanted visual confirmation without too much exceedance of the range of the 

field fluorometers. In general, visual confirmation of RWT 

is obvious at a concentration of 500 ppb and is possible at a 

concentration of 100 ppb. However, sample water in a clear 

vial would need to be viewed in front of a white background 

for concentrations less than 100 ppb because the solution 

would be tinted and not obvious otherwise. Certainly, at a 

concentration of 500 to 1,000 ppb, the dye in the discharge is 

visible to the human eye. 

The Martel (1913) and Dole (1906) empirical regression 

equations are commonly used to estimate the appropriate 

mass of tracer to use in a quantitative tracer test. Although 

numerous empirical equations have been developed to 

estimate tracer mass, only four had coefficient of determination (R2

) values greater than 0.6 and only the two mentioned 

above had R2 values greater than 0.9 (Worthington and 

Smart, 2003, table 1). Worthington and Smart (2003) 

compiled results from 185 tracer tests to obtain new regression coefficients for the Martel (1913) equation and the Dole 

(1906) equation (r2 > 0.9):

Martel (1913): Mass (grams) = 19*(LQC)0.95

Dole (1906): Mass (grams) = 0.73(TQC)0.97

where

L is straight line length from sink to spring in 

meters, 

Q is spring discharge in cubic meters per second, 
Fluorescent Dye Tracing 17

C is concentration in parts per million, and 

T is travel time (consistent unit in seconds). 

The travel time typically is not known. Based on our targeted 

peak dye concentration of 1 part per million (1,000 ppb) at 

the springs, table 3 gives the amount of dye estimated for the 

planned injection. Spring discharges were small during the 

training course, however, and may have been below the range 

of data used to create the regression equations for estimation of the mass of dye required for injection (Field, 2003; 

Worthington and Smart, 2003).

In preparing for the course, J. Van Brahana suggested that 

2 lbs of dye be ordered in case substantial rainfall preceded the 

experiment, which would cause flows at Langle Spring and 

Copperhead Spring to be closer to peak discharge and more 

dye would be necessary for visual confirmation. Two lbs of dye 

is more than the estimated amounts needed for visual confirmation at the small springflow rates during the class. RWT comes 

in liquid form, whereas fluorescein comes in a powder form 

and must be mixed. A rule of thumb in the oral tradition (no 

regression equation developed) for dye mass amounts is to use 

1 lb per mile distance between sink and spring; for example, 

the approximately 400 meters between the sink and Langle 

Spring or Copperhead Spring is approximately 0.2 mile, thus 

0.2 lbs would be required for the injection mass. Two lbs is 

10 times more than the rule of thumb, 50 to 100 times greater 

than the estimates provided in table 3 using the Martel (1913) 

regression, and 3 to 10 times greater than the estimates using 

the Dole (1906) equation. We were assuming, however, that 

because the dye mass would go to both Langle Spring and 

Copperhead Spring, the peak concentration would be half the 

1 ppm—or 500 ppb—at each spring. 

Although the amount of dye injected at the sink on 

Monday November 13, 2017, at 2250 Central Standard Time 

(CST), should have been carefully measured, a graduated 

cylinder was not available, so we put half of the mixed volume 

of dye (approximately 1 lb) into the sinking stream to ensure a 

strong visual signal. Photographs of the sinking dye and field 

team are shown in figure 15. If there is concern about dye 

entering a downstream user intake, the lower estimate of dye 

should be used; however, there is no such issue at the SEW.

On Monday, November 13, 2017, Joshua Blackstock and 

Dan Wagner installed new batteries and powered on the PME 

Cyclops-7 field fluorometer and data logger (serial number 

473746) at Langle Spring at 1632 CST. At 1743 CST, they 

powered on the PME Cyclops-7 field fluorometer and data 

logger (serial number 196807) at Copperhead Spring and 

submerged the equipment at 1758 CST). Note that the time and 

dates stored within the two data loggers were not reset to match 

exactly or match the watch time recorded in the instructor’s 

field notes (image of field notes available in Kuniansky, 2019). 

Thus, the date and time should be adjusted according to the 

times from the field notes as to when the fluorometer and data 

logger were powered up, knowing that the measurements were 

recorded every 5 minutes starting 5 minutes after the unit was 

powered up. A good practice for all future projects and data 

collection would be to set the date and time within the data 

loggers with an atomic clock, using the same laptop computer, 

such that both data loggers have the same date and time setting. 

Additionally, all time keepers should synchronize their watches 

to the atomic clock time. (Note that class attendees were 

instructed to set their watches to the same time on Monday, 

but the instructors did not check all the students’ watches.) The 

field fluorometers were calibrated to standards prepared in the 

laboratory by Joshua Blackstock prior to the course and set to 

read out in parts per billion. The field fluorometers could be 

set to raw uncalibrated voltage and grab samples could be used 

with the spectra-fluorometer to calibrate the raw uncalibrated 

field fluorometer voltage data based on standards and the field 

grab samples.

Owing to background interference from the native 

groundwater, native spring water was used for dilution to 

create standards in the laboratory (one at 1,000 ppb and the 

other at 500 ppb RWT). The spectra were measured with the 

low-sensitivity mode on the Shimadzu spectra-fluorometer 

because the high-sensitivity setting caused the spectra output 

to peak and plateau. This peaking is due to optical oversaturation of the light sensor used in the high-sensitivity mode. It 

would also have been good to have 100 and 10 ppb standards; 

however, by assuming that the 0,0 intercept represents no 

RWT, a calibration equation (Predicted RWT concentration 

in ppb = 16.644 × intensity at 575 nanometers − 2.1113) was 

developed for the RWT concentration at a wavelength peak of 

575 nanometers (fig. 16). 

We expected the RWT dye to appear at Copperhead 

Spring in about 11 to 12 hours (by 1000 to 1100 CST 

Tuesday, November 14) and at Langle Spring in about 16 to 

17 hours (by 1600 CST Tuesday). However, dye never made 

it to Copperhead Spring throughout the week or through 

December 2, 2017, when the field fluorometers were removed. 

Dye was not visible before sunset at about 1700 CST on 

Tuesday, November 14, 2017, at Langle Spring. Grab samples 

were collected at approximately hourly intervals starting 

around noon on Tuesday, November 14 at both springs, 

and sample collection continued until just after midnight 

on Wednesday, November 15. Bottles were labeled by the 

student collecting the sample with spring name, date, and time; 

resulting concentrations from laboratory analyses conducted 

Wednesday, November 15, by Joshua Blackstock are provided 

in table 4. 

On the basis of the grab samples, the leading edge of the 

dye appeared at Langle Spring between 2012 and 2238 CST 

almost 23 hours after the dye was placed into the sinking 

stream. There was no sign of dye visible at Langle Spring until 

late in the evening at about 2000 CST on November 14, 2017, 

when Eve Kuniansky thought there was a tinting of pink in 

the discharge at Langle Spring. By 2200 CST, more people 

agreed they saw the pink tint in the discharge at Langle Spring. 

By 0015 CST, on November 15, all those still in attendance 

concluded pink water was observed by the time the last grab 

sample was collected. The spectra for all the grab samples at 

Langle Spring reflected some background interference and only 

the last three samples had discernible RWT detection peaks at a 

wavelength of 575 nm above the background interference peak 

at 559 nm (fig. 17).
18 Interpretation of Dye Tracing Data Collected at the Savoy Experimental Watershed, Savoy, Arkansas

Table 3. Estimated mass of dye required for 1 part per million at Langle Spring and Copperhead Spring, Savoy Experimental 

Watershed, Arkansas.

[L, length; C, concentration; M, mass; m, meter; Q, discharge; T, time; m3/s, cubic meter per second; g, gram; Kg, kilogram]

Spring Length (m) Q (m3/s) T (s)

Martel (1913)

M = 19*(LQC)0.95 

Dole (1906)

M = 0.73*(TQC)0.97

Mass (g) Mass (Kg) Mass (g) Mass (Kg)

Langle 433 0.002 59400 16.557 0.017 75.144 0.075

Copperhead 374 0.001 41400 7.456 0.007 27.028 0.027

Figure 15. Photographs of RhodamineWT sinking underground at end of the sinking 

stream location latitude 36.116772 longitude -94.341883 North American Datum 1983 

(photograph by Eve Kuniansky, November 13, 2017 2250 Central Standard Time) and 

dye injection field crew (photograph by Joshua Blackstock, November 13, 2017, at 

2305 Central Standard Time).

res19_hwca00_0012_fig14

0.5

1.5

2.5

3.5

4.5

0

1.0

–0.5

–1.0

2.0

3.0

4.0

540 550 560 570 580

Low-intensity readings from Shimadzu RF-5301

Wavelength, in nanometers

Background contaminant

peak is at 560 for

Copperhead Spring 

Background contaminant peak

is at 559 for Langle Spring

Copperhead Spring

11/14/2017 at 1200

Langle Spring 11/14/2017

at 1030

EXPLANATION

Figure 14. Low-sensitivity spectra interference from background samples at Langle Spring and 

Copperhead Spring, Savoy, Arkansas.
Fluorescent Dye Tracing 19

0

200

400

600

800

1,000

1,200

0 10 20 30 40 50 60 70

Predicted RWT concentration in

parts per billion = 16.644 x intensity

at 575 nanometers – 2.1113

Coefficient of determination (R2

) = 0.9999

Intensity of 575 nanometer peak (relative units)

RhodamineWT concentration, in parts per billion

10

0

20

30

40

50

60

70

540 550 560 570 580 590 600 610 620 630 640 650 660 670 680

Intensity from Shimadzu

Wavelength, in nanometers

Intensity, in parts per billion

RD3.ASC 1,000

RD4.ASC 500

EXPLANATION

A

B

Figure 16. A, Low-sensitivity spectra from calibration standards. B, Linear calibration equation for 

converting intensity to concentration for RhodamineWT (RWT).
20 Interpretation of Dye Tracing Data Collected at the Savoy Experimental Watershed, Savoy, Arkansas

Table 4. Grab sample laboratory analysis at Copperhead and Langle Springs.

[intensity, dimensionless; ppb, parts per billion; PME, Precision Management Engineering, Inc.]

Date Time Sample 

name

Peak intensity at 

575 nanometers

Laboratory concentration 

(ppb)

Field fluorometer

(ppb)

Visible by

eye

Copperhead Spring (using field fluorometer)

11/14/2017 12:00 C1 none nondetect 1.16 No

11/14/2017 13:00 C2 none nondetect 0.64 No

11/14/2017 13:00 C3 none nondetect 0.64 No

11/14/2017 14:00 C4 none nondetect 0.70 No

11/14/2017 15:00 C5 none nondetect 0.37 No

11/14/2017 16:00 C6 none nondetect 0.45 No

11/14/2017 17:00 C7 none nondetect 0.95 No

11/14/2017 18:00 C8 none nondetect 0.67 No

11/14/2017 19:23 C9 none nondetect 0.40 No

11/14/2017 20:27 C10 none nondetect 0.30 No

11/14/2017 21:00 C11 none nondetect 0.35 No

11/14/2017 22:49 C12 none nondetect 0.30 No

Langle Spring (using PME field fluorometer)

11/14/2017 10:30 L1 none nondetect 0.44 No

11/14/2017 12:00 L2 none nondetect 0.41 No

11/14/2017 13:00 L3 none nondetect 0.54 No

11/14/2017 14:15 L4 none nondetect 0.37 No

11/14/2017 15:00 L5 none nondetect 0.45 No

11/14/2017 17:00 L6 none nondetect 0.67 No

11/14/2017 18:04 L7 none nondetect 1.22 No

11/14/2017 19:03 L8 none nondetect 5.41 No

11/14/2017 20:12 L9 none nondetect 29.42 Tinted??

11/14/2017 22:38 L10 8.84 145 216.35 Tinted yes

11/14/2017 23:00 L11 11.372 187 313.80 Yes?

11/15/2017 0:15 L12 23.1 382 572.79 Obvious

Figure 17. Graphs of spectra-fluorometer analyses for 

grab samples collected at Langle Spring (low-sensitivity 

setting), Savoy, Arkansas, November 14–15, 2017.

540 550 560 570 580 590 600 610 620 630 640 650 660 670 680

11/14/2017 at 1030 CST

11/14/2017 at 1200

11/14/2017 at 1300

11/14/2017 at 1415

11/14/2017 at 1500

11/14/2017 at 1700

11/14/2017 at 1804

11/14/2017 at 1903

11/14/2017 at 2012

11/14/2017 at 2238

11/14/2017 at 2300

11/15/2017 at 0015

–5

0

5

10

15

20

25

Wavelength, in nanometers

Intensity low setting on model RF-5301

EXPLANATION
Fluorescent Dye Tracing 21

Unfortunately, the grab sample concentration from the 

spectra-fluorometer analyses did not match the readings on the 

PME field fluorometer from approximately the same time, and 

the background concentrations on the PME field fluorometers 

were non-zero. Additionally, the average background concentration for the two PME field fluorometers, calculated on the basis 

of readings made prior to dye injection, did not match exactly 

(table 5). However, from the laboratory spectra-fluorometer, 

the background fluorescence (29.42 ppb) is a large part of the 

signal for sample L9 collected at 2012 CST. Thus, the spectrafluorometer is less sensitive than the PME field fluorometer 

for quantification of RWT at lower concentrations owing to 

this background interference peak. In reviewing the higher 

sensitivity sensor setting file for Langle Spring grab sample L9 

(not shown), a second peak at 575 could not be identified. As 

shown in table 5, there is a higher background concentration 

at Copperhead Spring, as well as a greater range and standard 

deviation, than in the data from Langle Spring even though 

both devices were calibrated using the same standards. It is 

possible that this difference is due to background interference 

results from the different groundwater source areas. Pink RWT 

coloration was not observed at Copperhead Spring throughout 

the rest of the week, whereas Langle Spring remained pink for 

the duration of the course (fig. 18).

Using a background RWT concentration of 1 ppb at 

Langle Spring necessitated setting all values less than 1 ppb 

to zero and subtracting 1 ppb from the rest of the PME 

field-fluorometer values to set up the data for use with the 

QTRACER2 software (Field, 2002). The QTRACER software 

analyzes the input data for tracer-breakthrough analysis. The 

adjusted RWT concentration at the time of removal of the 

equipment was 5 ppb, indicating that the concentration had 

almost returned to background levels (fig. 19). By collecting 

data every 5 minutes, the graph of the data is smooth (fig. 19). 

The elapsed transport time for the RWT from the time of injection to when the leading edge reached Langle Spring at about 

1900 CST was 1,135 minutes (18 hours and 55 minutes). The 

peak concentration was 1,313 ppb, which is slightly above 

the maximum concentration range of the field fluorometer of 

1,000 ppb. The peak occurred after 1,860 minutes (31 hours). 

Using these background-adjusted data, RWT dye recovery was 

96 percent for this experiment. This percentage of recovery is 

unusually good and indicates that the PME field fluorometer 

may be inaccurately calibrated because recovering almost 

100 percent of dye is almost unheard of in the field, especially 

when the shape of the curve indicates some sorption of dye 

(note the long tail on the breakthrough concentration curve 

[fig. 19]). A conservative tracer such as chloride (fig. 10) would 

be expected to have a more symmetric shape with no long tail as 

it returns to its background value. 

The grab sample results were used to calibrate the PME 

field-fluorometer data and set up a second QTRACER2 dataset. 

On the basis of a line fit through the three grab sample values 

(slope of 0.6821, intercept of −12.768, and a coefficient of 

determination (R2

) of 0.9896 (fig. 20A, equation A: Predicted 

laboratory RWT concentration = 0.6821 × field concentration 

− 12.768), concentrations less than 22 ppb for RWT cannot be 

determined. However, if the y-intercept is forced to be 0 ppb, 

we get a linear function that still fits the PME field-fluorometer 

data and still has a very good R2 of 0.9874 with a slope of 

0.6523 (fig. 20B, equation B: Predicted laboratory RWT 

concentration = 0.6523 × field concentration). Nevertheless, it 

would have been better to have had additional standards at the 

100, 10, and 1 ppb for RWT and not have exceeded the range 

of detection for the PME field-fluorometer RWT concentration. 

For this test, however, if half of the RWT had gone to Copperhead Spring and half to Langle Spring as planned, then perhaps 

the peak concentrations would have been ideal at both springs. 

Additionally, it would have been better to exactly measure the 

mass of dye injected. Nevertheless, by using about half of the 

volume based on the height of the liquid in the bottle yielded 

a close approximation (probably within 10 percent as that 

would be plus or minus a half inch of the height of liquid in the 

cylindrical bottle). On the basis of the PME field-fluorometer 

data, equation B, and assuming a constant discharge 0.1 ft3/s 

and 1 lb of dye injected as a slug, 63 percent of the mass was 

recovered. The leading edge and peak travel times are the same 

for the original PME data. (Note: We would have had to set all 

values below 22 ppb to a nondetect, which would have resulted 

in negative RWT values using equation A, which is why that 

equation was rejected.). Therefore, with equation B, the peak 

concentration based on laboratory adjustment of the field peak 

concentration of 1,313 ppb (fig. 19) is calculated as 856 ppb 

from the linear regression equation (see fig. 20B).

The QTRACER2 program provides other useful 

information that has been compiled into table 6. Most of the 

calculated values in table 6 are the same for the original PME 

field-fluorometer data and for the PME field-fluorometer data 

that is adjusted to the laboratory concentration; the adjustment 

only modifies the concentration and does not change the shape 

of the breakthrough curve. However, the big difference in mass 

recovered has a large effect on the accuracy index computed 

by QTRACER2. The Reynolds number is calculated assuming 

a pipe diameter of 1.4 meters (estimated subsurface conduit 

diameter to the spring). Reynolds numbers are dimensionless 

numbers used in fluid mechanics to indicate whether flow is 

laminar or turbulent. The Reynolds number represents the 

ratio of fluid inertial to viscous forces. The upper and lower 

Table 5. Statistics on background rhodamineWT parts per 

billion readings from the field fluorometers installed at Langle 

and Copperhead Springs, Savoy, Arkansas.

[Units are parts per billion]

Statistic Langle Copperhead

Average 0.42 1.63

Maximum 0.80 4.25

Minimum 0.03 0.27

Median 0.43 1.39

Standard deviation 0.14 0.98
22 Interpretation of Dye Tracing Data Collected at the Savoy Experimental Watershed, Savoy, Arkansas

critical Reynolds numbers are the values above which 

flow becomes turbulent and below which flow becomes 

laminar and is a function of flow velocity, fluid density, and 

viscosity. In pipe-flow experiments when flow goes from 

laminar to turbulent this occurs at the upper critical Reynolds 

number, and when flow goes from turbulent to laminar this 

occurs at the lower critical Reynolds number. Thus, flow 

would most likely be laminar if the Reynolds number is 

computed to be near the lower critical Reynolds number for 

pipe flow. The lower critical Reynolds number for pipes is 

2,000, and the upper critical Reynolds number for pipes is 

10,000. Therefore, it is unclear whether there was turbulent 

flow during this test. The Peclet number is the ratio of the 

rate of advection versus the rate of diffusion and indicates 

that advection was more dominant than diffusion for this 

tracer test. Diffusion is dominant for Peclet numbers below 

0.4, and the transition between diffusion-dominated and 

advection-dominated transport occurs for Peclet numbers 

from 0.4 to 6 (Field, 2002).

This quantitative test was somewhat anomalous 

compared to previous tracer tests conducted at the site 

because discharge at Copperhead Spring and Langle 

Spring was very small. This test conclusively proved that 

Copperhead Spring is not the base spring in the flow system. 

The test proved that Copperhead Spring receives water from 

the sinking stream only after the spring basin water levels 

are higher than at the dry conditions that were present during 

this test when Copperhead Spring was at extremely low 

flow. Greg Stanton and J. Van Brahana stated that they have 

never conducted a tracer test at a low flow such as during 

this test and never one where dye injected into this sinking 

stream did not show up at Copperhead Spring first and then 

at Langle Spring. 

Figure 18. Images of Langle Spring and Copperhead Spring, Savoy, Arkansas, on November 15, 2017. From left to right: Looking 

down into Langle Spring orifice at 0008 Central Standard Time (photograph by Eve Kuniansky); Langle Spring outflow behind the weir 

1109 Central Standard Time (photograph by Cassie Crow); and Copperhead Spring at 1424 Central Standard Time (photograph by 

Eve Kuniansky).
Fluorescent Dye Tracing 23

res19_hwca00_0012_fig19

0

200

400

600

800

1,000

1,200

1,400

0 2 4 6 8 10 12 14 16 18 20

Concentration, in parts per billion

Elapsed time, in days, from November 13, 2017, at 2250

Figure 19. Breakthrough curve for RhodamineWT data 

at Langle Spring, Savoy, Arkansas.

Figure 20. Linear regressions for calibration of fieldfluorometer RhodamineWT (RWT) concentration to 

laboratory estimated grab sample values. A, No set 

intercept. B, Intercept set to zero.

100

150

0

50

200

250

300

350

400

450

A

Predicted laboratory RWT concentration =

0.6821 x field concentration – 12.768

Coefficient of determination (R2) = 0.9896

Predicted laboratory RWT concentration =

0.6523 x field concentration

Coefficient of determination (R2

) = 0.9874

100

150

0

50

200

250

300

350

400

450

0 100 200 300 400 500 600 700

Field fluorometer concentration, in parts per billion

Laboratory spectra-fluorometer concentration, in parts per billion

B
24 Interpretation of Dye Tracing Data Collected at the Savoy Experimental Watershed, Savoy, Arkansas

Table 6. Summary of information from the QTRACER2 program.

[m3, cubic meter; m2, square meter; m, meter; mm, millimeter; m/d, meter per day; m/s, meter per second; m2/s, square meter per second; ppb, parts per billion]

Description of QTRACER2 computed result Field fluorometer data Field fluorometer data adjusted 

to lab concentration

Quantity of tracer recovered 0.96111 pounds 0.62693 pounds

Percent recovery of tracer injected 96.112 62.693

Accuracy index (0.0 = Perfect Recov.) 0.0389 0.3731

Total aquifer volume estimate 751.37 m3 same

Total aquifer surface area estimate 81,504 m2 same

Final tracer sorption coefficient (coef.) 0.37296E-03 m .54857E-02 m

Time to first arrival 1,135 minutes same

Time to peak concentration 1,860 minutes same

Concentration at peak 1,313.3 ppb 856.65 ppb

The mean tracer transit time 4,421.9 minutes same

Standard deviation for tracer time 4,255.4 minutes same

The mean tracer velocity 166.75 m/d same

Standard deviation for tracer velocity 157.54 m/d same

Dispersion coefficient 0.12497 m2

/s 0.12498 m2/s

Longitudinal dispersivity 64.750 m 64.754 m

Peclet number 7.9083 7.9076

The maximum tracer velocity 649.67 m/d same

Hydraulic head loss along channel 0.36693E-04 m 0.36694E-04 m

Estimated Reynolds number (based on estimated tube diameter of 1.3669 m)2,314 same

Estimated Froude number (based on estimated hydraulic depth 1.0735 m)5.95E-04 same

Molecular mass transport parameters

Shear velocity 0.86857E-03 m/s same

Estimated Schmidt number 1,140.00 same

Estimated Sherwood number 148.98 same

Mass transfer coef. from wall to flow 0.10899E-06 m/s same

Molecular diffusion layer thickness 9.1748 mm same

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implications for wellhead-protection strategies in westcentral Florida: U.S. Geological Survey Water-Resources 

Investigations Report 93–4171, 63 p. [Also available at 

https://doi.org/10.3133/wri934171.]

Rantz, S.E., and others, 1982, Measursement and computation of streamflow—Volume 1, Measurement of stage and 

discharge: U.S. Geological Survey Water Supply Paper 

2175, 313 p. [Also available at https://pubs.usgs.gov/wsp/

wsp2175/.]
26 Interpretation of Dye Tracing Data Collected at the Savoy Experimental Watershed, Savoy, Arkansas

Spangler, L.E., 2012, Hydrogeology of the Mammoth Spring 

groundwater basin and vicinity, Markagunt Plateau, Garfield, 

Iron, and Kane Counties, Utah: U.S. Geological Survey 

Scientific Investigations Report 2012–5199, 56 p., accessed, 

October 4, 2017, at https://doi.org/10.3133/sir20125199.

Spangler, L.E. and Susong, D.D., 2006, Use of dye tracing

to determine ground-water movement to Mammoth 

Crystal Springs, Sylvan Pass area, Yellowstone National 

Park, Wyoming: U.S. Geological Survey Scientific Investigations Report 2006–5126, 12 p., accessed August 5, 2015, at 

https://doi.org/10.3133/sir20065126.

Stanton, Gregory P., 1993, Processes and controls affecting 

anisotropic flow in the Boone-St. Joe aquifer in northwestern Arkansas: Fayetteville, Ark., University of Arkansas, 

unpublished M.S. thesis, 212 p. [Available from University 

of Arkansas Geosciences Department, Gearhart Hall, 340 N 

Campus Dr, Fayetteville, AR 72701.]

Taylor, C.J., 1997, Delineation of ground-water basins and 

recharge areas for municipal water-supply springs in a karst 

aquifer system in the Elizabethtown area, northern Kentucky: 

U.S. Geological Survey Water-Resources Investigations 

Report 96–4254, 22 p., accessed August 5, 2015, at

https://doi.org/10.3133/wri964254.

Unger, Timothy, 2004, Structural controls influencing groundwater flow within the mantled karst of the Savoy Experimental Watershed, northwest Arkansas: Fayetteville, Ark., 

University of Arkansas, unpublished M.S. thesis, 128 p. 

[Available from University of Arkansas Geosciences

Department, Gearhart Hall, 340 N Campus Dr, 

Fayetteville, AR 72701.]

U.S. climate data, 2018a, Fayetteville, Arkansas, climate 

and weather averages: U.S. climate data website, accessed 

April 13, 2018, at https://www.usclimatedata.com/climate/

fayetteville/arkansas/united-states/usar0189.

U.S. climate data, 2018b, Fayetteville, Arkansas, climate 

and weather averages: U.S. climate data website, accessed 

April 20, 2018, at https://www.usclimatedata.com/climate/

fayetteville/arkansas/united-states/usar0189/2017/11.

White, W.B., 1988, Geomorphology and hydrology of karst 

terrains: Oxford, U.K., and New York, Oxford University 

Press, 464 p. [Also available at https://doi.org/10.1002/

esp.3290150110.]

Worthington, S.R.H., and Smart, C.C., 2003, Empirical determination of tracer mass for sink to spring tests 

in karst, in Beck, B.F., ed., Sinkholes and the engineering and environmental impacts on karst: American Society of Civil Engineers, Geotechnical Special 

Publication No. 122, p. 287–295. [Also available at 

https://doi.org/10.1061/40698(2003)26 .
Appendixes 1–3
28 Interpretation of Dye Tracing Data Collected, at the Savoy Experimental Watershed, Savoy, Arkansas

Appendix 1. Instructor Profiles GW2227 Advanced 

Groundwater Field Techniques in Karst Terrains 

Fayetteville, Arkansas, November 13–17, 2017

Eve Kuniansky, Course Coordinator/Instructor 

U.S. Geological Survey—Water Mission Area

Integrated Modeling and Prediction Division

Earth Systems Modeling Branch

1770 Corporate Drive, Suite 500, 

Norcross, Georgia 30093

elkunian@usgs.gov

Office: 678–924–9211 Cell 404–548–9211

https://www.usgs.gov/staff-profiles/eve-l-kuniansky

Eve moved to the new Integrated Modeling and Prediction Division, Earth Systems Modeling Branch, October 1, 2017, and had been the Water Science Field Team 

Southeastern Region Groundwater Specialist, providing 

technical assistance for groundwater projects throughout the Southeastern U.S.A., Puerto Rico, 

and the Virgin Islands, since 1998. She has always liked science and nature and earned a degree 

in physics from Franklin and Marshall College in 1978 and Bachelor of Civil Engineering in 

1981, with highest honor, and Master of Science in Civil Engineering (hydrology/hydraulics) 

in 1982 (both from Georgia Institute of Technology). In January 1983, she began a career with 

the U.S. Geological Survey (USGS) and gained experience in surface-water modeling, project 

management, borehole geophysics, geologic mapping, field data collection, groundwater flow 

and transport simulation, geographic information system (GIS), karst hydrology, and aquifer 

hydraulics. Because of her expertise, Eve is frequently asked to provide training within the 

USGS and has been selected for short-term international assignments by the USGS International Water Resources Branch (China, Israel, Cyprus, Ethiopia, Kenya, and South Africa) 

where she has either conducted groundwater training or worked on groundwater projects. Eve 

has been interested in karst aquifers since 1986 when she encountered the Edwards-Trinity 

aquifer and has coordinated the USGS Karst Interest Group since 2000. 

Eve is coordinating this first course, but it is a team effort involving several of the former 

“Regional Groundwater Specialists” (Geoff Delin, Devin Galloway, Eve Kuniansky, and Rod 

Sheets), some noted USGS retirees that teach at the University of Arkansas (Van Brahana and 

Fred Paillet), the Fayetteville Office (Dan Wagner and Phil Hays, who also is on the faculty 

at the University of Arkansas), staff from the current Branch of Geophysics (Martin Briggs 

assisted by Marian Domanski from the Urbana, Illinois, office) and staff from the Texas Water 

Science Center that are involved in geophysical studies of the Edwards-Trinity aquifer (Greg 

Stanton, Jason Payne, Sam Wallace, and Jon Thomas). Additionally, Joshua Blackstock, a Ph.D. 

candidate at the University of Arkansas and a former USGS employee, is voluntarily assisting 

in the dye tracing part of this course.

 The intent of the course is to introduce attendees to field techniques used in the study of 

groundwater flow in karst and fractured rock aquifer systems, but not provide details on any 

topic because a full week could be spent on any of the methods presented. Another byproduct 

of these courses is the networking with others in the USGS. So enjoy!
Appendix 1 29

Joshua M. Blackstock, Instructor

Ph.D. Candidate

Department of Geosciences

University of Arkansas

216 Gearhart Hall,

Fayetteville, Arkansas 72701

jmblack@uark.edu

Joshua is a student at the University of Arkansas, 

working toward a Ph.D. in Geosciences. He received his 

B.S. in Geology from the University of Arkansas, Little 

Rock, in 2008 and his M.S. in Geology with First Class 

Honors from the University of Canterbury, New Zealand, 

in 2012. He was employed with the USGS at the Arkansas 

Water Science Center and Lower Mississippi Gulf Water Science Center as a Hydrologic Technician from 2006 to 2015 where he participated in data collection and analysis and coauthored 

publications for numerous groundwater and surface-water studies and monitoring programs. A 

portion of this work included tracing fluid flow in karst aquifer systems and implementation of 

geochemical tracing methods. His research is primarily focused on sources, movement, and geochemical evolution of crustal fluids encompassing deep- and shallow groundwater systems and, 

importantly, their interactions. Research methods include geochemical analysis, with emphasis 

on stable and radiogenic isotope geochemistry, numerical modeling, and the burgeoning field 

of low-cost environmental sensor platform fabrication and deployment. Experience and lessons 

learned from USGS experience in standardized protocols and “field checks” have been integral 

in development, management, and quality assurance and quality control for these platforms. 

For this course, Joshua assisted in the field component and lecturing on the collection, 

analysis, and interpretation of dye trace samples.

Van Brahana, Instructor

Research Scientist Emeritus (1999) 

U.S. Geological Survey, Water Resources Division 

Professor Emeritus (2013)

University of Arkansas

Department of Geosciences

Fayetteville, Arkansas 72701

brahana@uark.edu

Van Brahana received his formal education from the 

University of Illinois (B.A.) and the University of Missouri 

(M.A., Ph.D.). He has more than 50 years of hydrogeologic 

and karst teaching and research experience with the Illinois 

Geological Survey, the USGS, Vanderbilt University, the 

University of Arkansas (UA), consulting and participating in local, regional, and national technical review boards and consortia. Van initiated his USGS 

career as a Hydrologist in 1971 as part of the intense, 6-month training program at the Denver 

Training Center. He served in Mississippi, Tennessee, and Arkansas, the last assignment as a split 

USGS/UA assignment. His research has focused on tectonic control of groundwater flow boundaries, karst hydrogeology, and interdisciplinary involvement to address challenging environmental 

problems. Tom Sauer (U.S. Department of Agriculture—Agricultural Research Service) and Van 

initiated and instrumented the Savoy Experimental Watershed, a site that allows study of the longterm effects of sustainable animal production on karst lands. At the UA, Van has mentored and 

supervised scores of students and received multiple teaching awards and the Geological Society 

of America Distinguished Service Award; he has published more than 75 peer-reviewed technical 

papers, reports, and book chapters. He currently conducts pro bono water-quality sampling and 

dye tracing on Big Creek, site of a 6,500-pig concentrated animal feeding operation on a major 

tributary to Buffalo National River.
30 Interpretation of Dye Tracing Data Collected, at the Savoy Experimental Watershed, Savoy, Arkansas

Martin Briggs, Instructor

U.S. Geological Survey—Water Mission Area

Earth Systems Processes Division

Hydrogeophysics Branch

11 Sherman Place,

Storrs, Connecticut 06238

mbriggs@usgs.gov

Office: 860–487–7402 x19

https://www.usgs.gov/staff-profiles/martin-a-briggs

Martin earned a B.S. in Geology from the University 

of Massachusetts, Amherst, in 2002; his M.S. from the 

Hydrologic Sciences and Engineering Program at the 

Colorado School of Mines in 2009; and was awarded his 

Ph.D. in 2012 from Syracuse University. Although his 

specialty is in understanding and quantifying surfacewater/groundwater exchange processes, Martin works on 

a wide range of hydrological issues in his position as research hydrologist with the Hydrogeophysics Branch at the USGS. The Branch supports State Water Science Centers when hydrogeophysical tools and training are required, and the staff collaborates with academic institutions 

on pioneering water research. One of the Branch’s central missions is training and method 

development, so Martin travels around the country instructing at workshops and field testing 

new methodology. Martin has specifically contributed to advancements in the application of 

heat tracing methodology and integrating fine-scale electrical geophysics at the groundwater/

surface-water interface. Much of his current research involves defining the physical hydrogeological template that controls niche aquatic habitat and beneficial biogeochemical processes in a 

time of baseline change. 

For this course Martin led the demonstration of heat tracing methodology to locate and 

quantify exchanges of surface and groundwater in karst regions. For example, the infrared 

image below, taken at the Fayetteville, Ark., site, shows how relatively warm groundwater 

discharge from karst springs (hot colors) can be pinpointed for geochemical sampling and 

discharge measurements.
Appendix 1 31

Geoff Delin, Instructor

Retired from the Water Science Field Team, 

Groundwater Specialist, Central U.S.A.

U.S. Geological Survey

Denver Federal Center

Box 25046, Mail Stop 406

Denver, Colorado 80225

delin@usgs.gov

Office: 303–236–1471

https://www.usgs.gov/staff-profiles/geoffrey-delin

Geoff retired from the USGS (April 2017) as the Water Science Field Team Groundwater Specialist for the Central part of the United States, including the Southwest Region and the 

western half of the Midwest Region of the USGS. He currently has USGS emeritus status. Prior 

to Geoff’s retirement, he provided technical assistance to groundwater projects in the Arizona, 

Colorado, Iowa, Kansas, Minnesota, Missouri, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, and Utah Water Science Centers. Geoff received his undergraduate 

and graduate education in Geology and Hydrogeology from the University of Minnesota. Prior 

to joining the USGS, Geoff worked for 2 years as a geologist at a consulting firm. He began his 

USGS career as a Hydrologic Technician in 1979 in the Minnesota District. As a Technician, his 

duties included running the District auger drilling rig. As a Hydrologist, Geoff conducted numerous investigations on groundwater quality and quantity, including simulation of groundwater flow 

and solute transport. Geoff was the site coordinator and Research Grade Evaluation researcher 

for the Management Systems Evaluation Area and Bemidji Crude-Oil Spill Toxics Substances 

Hydrology research studies from 1992 to 2008. His research activities involved evaluating the 

fate and transport of agricultural chemicals and petroleum hydrocarbons, as well as estimation of 

groundwater recharge using multiple methods, including conducting several tracer tests. Geoff 

served as the Minnesota Water Science Center Groundwater Specialist for about 12 years. Geoff 

is the author or coauthor of more than 65 hydrogeologic publications and has given more than 75 

technical conference presentations. Geoff has been the instructor for the USGS Groundwater Field 

Methods course, the Groundwater/Surface-Water Interaction course, as well as for webinars relating to aquifer testing, well integrity testing, and model archiving.

Marian Domanski, Instructor

U.S. Geological Survey

Illinois-Iowa Water Science Center

405 N Goodwin Avenue,

Urbana, Illinois 61801

mdomanski@usgs.gov

Office: 217–328–9758

Marian Domanski has been with the USGS IllinoisIowa Water Science Center in Urbana, Illinois, since 2011. 

Marian received his B.S. and M.S. in Civil Engineering 

from the University of Illinois at Urbana-Champaign. 

Since beginning with the USGS, Marian has worked 

with developing software tools for scientific applications, 

including emerging technologies for real-time estimates 

of suspended-sediment characteristics. He has also been 

involved with the development of USGS policy for realtime estimates of suspended-sediment concentration using 

acoustic backscatter. Marian has recently co-instructed the 

USGS Sediment Acoustic Index Methods course.
32 Interpretation of Dye Tracing Data Collected, at the Savoy Experimental Watershed, Savoy, Arkansas

Phillip D. Hays, Instructor

U.S. Geological Survey-LMG, University of 

Arkansas

University of Arkansas

340 N Campus Drive

Geosciences Department, 216 Gearhart Hall

Fayetteville, Arkansas 72701

pdhays@usgs.gov

Office: 479–575–7343

https://www.usgs.gov/staff-profiles/phillip-d-hays

Phil Hays is a hydrogeologist with a background in stable isotope geochemistry and groundwater geochemistry. He completed an M.S. at Texas A&M University in 1986 and a Ph.D. at 

Texas A&M in 1992. He worked as an exploration geologist with Sun Oil Company from 1985 

to 1988 before joining the USGS in 1992. During his USGS career he has worked in groundwater 

modeling, aquifer characterization, karst hydrology, and contaminant hydrology. Dr. Hays joined 

the Geoscience faculty with the University of Arkansas in 2000 in a USGS cooperative study 

and works half time as a research professor. Dr. Hays pursues research in application of stable 

isotopes and other geochemical indicators in delineating movement and behavior of contaminants 

in groundwater systems and in characterizing paleoclimate and paleoenvironment. He has worked 

across the United States and abroad with the goals of advancing science in management and 

sustainable use of natural resources and protection of the human environment; this work involves 

such diverse research areas as delineating the relation between karst development and water quality in the Ozark Mountains, mercury contamination in the Guianas Ecoregion, the thermal springs 

of Hot Springs National Park, sustainable resource use curricula development in central Africa, 

salt-marsh restoration in coastal New England, and characterization of groundwater impacts in 

shale-gas fracking production areas in central Arkansas..

Fred Paillet, Instructor

Retired U.S. Geological Survey Geophysicist

Adjunct Professor, University of Arkansas

340 N Campus Drive

Geosciences Department, 216 Gearhart Hall

Fayetteville, Arkansas 72701

fredp@cox.net

Office phone: 479–575–3355

Fred Paillet is an Adjunct Professor of Geosciences at 

the University of Arkansas. He served as the Chief of the 

USGS Borehole Geophysics Research Project in Denver 

from 1983 until his retirement in 2002. Since then he has 

had temporary appointments at the University of Maine, 

The University of Rennes (France), and the University of 

Queensland (Australia). His work in karst aquifer characterization included studies in Minnesota, Wisconsin, 

Illinois, Texas, Tennessee, and Arizona.
Appendix 1 33

Jason D. Payne, Instructor

U.S. Geological Survey

Texas Water Science Center

3745 S. Jackson Street

San Angelo, Texas 76903

jdpayne@usgs.gov

Office: 325–944–4600 x28

Jason Payne is a geophysicist with the USGS in San 

Angelo, Tex., with more than 10 years of experience in 

many near-surface geophysical methods and environments. 

Jason graduated from Angelo State University in Applied 

Physics in 2006. Since graduation, Jason has been with 

the USGS as part of the Texas Water Science Center’s 

geophysics team. He has worked on multiple large- and 

small-scale projects involving a wide range of geophysical 

capabilities.

Greg Stanton, Instructor

U.S. Geological Survey

Texas Water Science Center

1505 Ferguson Lane

Austin, Texas 78754

gstanton@usgs.gov

Office: 512–927–3558

Greg Stanton is an Associate Director for Science in 

the USGS Texas Water Science Center in Austin, Texas, 

coordinating groundwater and geophysics activities in 

the Center. Greg began his USGS career 25 years ago as 

a volunteer in the Fayetteville Project Office and subsequently spent 10 years as a Hydrologist in the Arkansas 

Water Science Center and 14 years in Texas as Groundwater Specialist and Associate Director. During that time Greg 

has worked on many groundwater and geophysics projects ranging from contaminant studies at Department of 

Defense sites, to karst studies in the Ozarks and the Edwards aquifers, to groundwater modeling 

in the Mississippi River Alluvium. Prior to his USGS career, Greg worked 7 years in the petroleum industry collecting and analyzing borehole geophysical data in west Texas, the Southeastern 

United States, and the Gulf Coast and offshore. Greg holds B.S. and M.S. degrees in Geology 

from the University of Arkansas.
34 Interpretation of Dye Tracing Data Collected, at the Savoy Experimental Watershed, Savoy, Arkansas

Jonathan Thomas, Instructor

U.S. Geological Survey

Geophysicist—North Texas

Texas Water Science Center

501 W. Felix Street, Building 24

Fort Worth, Texas 76115

jvthomas@usgs.gov

Office: 682–316–5036

Jon is a geophysicist with the Texas Water Science 

Center North Texas Program Office in Fort Worth, Tex. 

Jon earned a B.S in Applied Physics with a minor in 

Mathematics from Angelo State University in 2008. Jon 

started in the San Angelo Field Office as a Student Career 

Experience Program Intern with the Texas Water Science 

Center in February 2008 and joined the USGS full time after his graduation in December 2008. 

His experience with the Texas Water Science Center geophysical team consists primarily of borehole geophysics and conceptual model development. Jon is licensed on the USGS Radiation User 

Permit as Radiation Logging Supervisor. Additional experience includes geodatabase development, geophysical data collection, GIS analyses, data processing, and groundwater/surface-water 

interaction studies.

Dan Wagner, Instructor

U.S. Geological Survey

Lower Mississippi-Gulf Water Science Center

700 W. Research Center Boulevard, Suite 2411

Mail Stop 36

Fayetteville, Arkansas 72701

Dan is a Hydrologist in the Fayetteville, Arkansas, 

office of the USGS Lower Mississippi-Gulf Water Science Center. He received his B.S. in Geology from the 

University of Arkansas in Fayetteville in 2005 and M.S. in 

Geology from the University of Arkansas in Fayetteville in 

2008. Dan started as a Student Career Experience Program 

Hydrologic Technician in the Arkansas Water Science Center in 2006 and accepted a Hydrologist position in 2008. 

His work has focused on topics related to surface-water hydrology, including 2D flow modeling, 

surface-water dye tracing/dilution, seepage runs, bathymetric surveys, and terrestrial light detection and ranging surveys, and statistical work related to trends in streamflow data, regional regression modeling of annual peak flows, and work on the National Skew project.
Appendix 1 35

Sam Wallace, Instructor

U.S. Geological Survey

Texas Water Science Center

501 W. Felix Street, Building 24

Fort Worth, Texas 76115

dswallace@usgs.gov

Office: 682–316–5037

Sam is a Hydrologist with the Texas Water Science Center North Texas Program Office in 

Fort Worth, Tex. Sam earned a B.S in Environmental Science from Oklahoma State University in 

2013 and an M.S. in Environmental Geology from Rutgers University, Newark, New Jersey, in 

2015. For his M.S., he studied the benefits of combining geophysical surveys, specifically nuclear 

magnetic resonance and spectral induced polarization (SIP). As a student, Sam was an Environmental Protection Agency Greater Research Opportunities Undergraduate Fellow and interned 

with the EPA Region 2 Division of Environmental Science and Assessment in Edison, N.J. Sam 

became a Pathways Intern with the Texas Water Science Center in 2014 and joined the USGS full 

time after his graduation in 2015. His experience with the Texas Water Science Center geophysical team consists primarily of borehole geophysical logging and land and waterborne resistivity 

surveys. Additional experience includes python programming, GIS analyses, peak streamflow 

frequency analyses, and surface-water modeling.

Devin Galloway, Planner

U.S. Geological Survey—Water Mission Area

Earth System Processes Division 

Water Cycle Branch

Indiana Water Science Center

5957 Lakeside Boulevard

Indianapolis, Indiana 46278

dlgallow@usgs.gov

Office: 916–801–2040

https://www.usgs.gov/staff-profiles/

devin-lynn-galloway

As of October 1, 2017, Devin is a Hydrologist in the 

USGS Water Cycle Branch of the Earth System Processes 

Division but was the Water Science Field Team Groundwater Specialist for the Western Territory, 

providing technical assistance to groundwater projects in Alaska, California, Hawaii (and other 

Pacific Islands), Idaho, Montana, Nevada, Oregon, Washington, and Wyoming. He has worked 

with the USGS since 1978 in the Illinois Water Science Center, the Nuclear Hydrology Program 

in Colorado and Nevada, the California Water Science Center, the National Research Program, 

and the Western Region Hydrologist’s office. Devin has a B.A. in Biology (Indiana University), 

M.S. in Environmental Science (Indiana University), and an M.S. in Civil and Environmental 

Engineering (University of Illinois). He is the author or coauthor of more than 75 hydrogeology 

publications and currently serves as a member and past chair (2010–15) of the United Nations 

Educational, Scientific and Cultural Organization Working Group on Land Subsidence, is on the 

Board of Directors of the U.S. Chapter of the International Association of Hydrogeologists, and 

is an Associate Editor for the Hydrogeology Journal. Devin has taught the USGS Groundwater 

Principles and Groundwater Concepts and Modeling courses, as well as USGS-sponsored TimeSeries Analysis, Aquifer Hydraulic Testing and Field Methods, and Land Subsidence Monitoring, 

Analysis, and Modeling courses in several national and international workshops. Devin was helpful in formulation of this course but was in Spain during the week of the course..
36 Interpretation of Dye Tracing Data Collected, at the Savoy Experimental Watershed, Savoy, Arkansas

Rodney (Rod) Sheets, Planner

U.S. Geological Survey—Water Mission Area

Office of Quality Assurance, Groundwater Specialist

6480 Doubletree Avenue

Columbus, Ohio 43229

rasheets@usgs.gov

Office: 614–430–7710

https://www.usgs.gov/staff-profiles/rodney-a-sheets

Rod currently (October 1, 2017) serves as the USGS 

National Groundwater Specialist in the Office of Quality 

Assurance but was a Water Science Field Team Groundwater Specialist for the Northeast/Midwest part of the United 

States including the Northeast Region and the eastern half 

of the Midwest Region of the USGS. Rod received his 

undergraduate and graduate education in Geology/Geophysics and Hydrogeology from The Ohio 

State University. Prior to and during college, he drilled water and shallow oil/gas wells in eastern 

Ohio. He began his USGS career as a Geologic Technician/Geologist in 1984 in the Office of 

Earthquakes, Menlo Park, California, then as a Hydrologic Technician in 1987 at the USGS Ohio 

District, running field trips, sitting on drilling rigs, and helping the Studies section. After becoming a Hydrologist in 1988, Rod conducted numerous investigations on groundwater quality and 

quantity, including geophysical studies, simulation of groundwater flow, and surface/groundwater 

interactions. Rod served as the Ohio Water Science Center Groundwater Specialist for about 10 

years and has been in his current position for 10 years. Rod is the author or coauthor of nearly 

30 hydrology publications and has given more than 30 technical conference presentations. Rod 

has been the instructor for several USGS courses, including USGS Groundwater Field Methods, 

Groundwater Concepts, Surface Geophysics, and Use of Heat as a Tracer, as well as for webinars 

relating to aquifer testing, well integrity testing, model and geophysical data archiving, and tape 

calibration. Unfortunately, he had to cancel from participation in the field part of the course.
Appendix 2 37

Appendix 2. Savoy Experimental Watershed Theses, 

Dissertations, and Papers

[All unpublished theses and dissertations 

can be obtained from University of 

Arkansas. Some are available online at 

https://libraries.uark.edu/.]

Al-Qinna, Mohammed, 2004, Measuring and modeling soil water and solute 

transport with emphasis on physical 

mechanisms in karst, Savoy Experimental Watershed, Arkansas: Fayetteville, 

University of Arkansas, unpublished M.S. 

thesis.

Al-Rashidy, Said, 1999, Hydrogeologic 

controls of groundwater in the shallow 

mantled karst aquifer, Copperhead Spring, 

Savoy Experimental Watershed, northwest Arkansas: unpublished M.S. thesis, 

University of Arkansas, 124 p.

Brahana, J.V., Hays, P.D., Kresse, T.M., 

Sauer, T.J., and Stanton, G.P., 1999, The 

Savoy Experimental Watershed—Early 

lessons for hydrogeologic modeling 

from a well-characterized karst research 

site, in Palmer, A.N., Palmer, M.V., and 

Sasowsky, I.D., eds., Proceedings, Karst 

Modeling, February 24–24, 1999: Charlottesville, Virginia, Karst Waters Institute 

Special Publication 5, p. 247–254.

Curtis, D.L., 2000, An integrated rapid 

hydrogeologic approach to delineate areas 

affected by advective transport in mantled 

karst, with an application to Clear Creek 

Basin, Washington County, Arkansas: 

Fayetteville, University of Arkansas, 

unpublished Ph.D. dissertation, 121 p.

Dixon, B., 2001, Application of neuro-fuzzy 

techniques to predict ground-water vulnerability in northwest Arkansas: Fayetteville, University of Arkansas, unpublished 

Ph.D. dissertation, 262 p.

Hamilton, S., 2001, Survival of E. coli in 

stream and spring sediments: Fayetteville, 

University of Arkansas, unpublished M.S. 

thesis, 48 p.

Hobza, C., 2005, Ground-water quality 

near a swine waste lagoon in a mantled 

karst terrane in northwestern Arkansas: 

Fayetteville, University of Arkansas, 

unpublished M.S. thesis, 76 p.

Laincz, J., 2011, Investigation of nitrate 

processing in the interflow zone of 

mantled karst, northwestern Arkansas, in 

Kuniansky, E.L., ed., 2011, U.S. Geological Survey Karst Interest Group Proceedings, Fayetteville, Arkansas, April 26–29, 

2011: U.S. Geological Survey Scientific 

Investigations Report 2011–5031, 212 p., 

https://doi.org/10.3133/sir20115031.

Laincz, J., 2014, Investigation of the flow 

and fate of nitrate in epikarst at the 

Savoy Experimental Watershed, northwest Arkansas: University of Arkansas 

Theses and Dissertations 2248, 149 p., 

https://scholarworks.uark.edu/etd/2248/.

Leh, M., 2006, Quantification of rainfallrunoff mechanisms in a pasture-dominated 

watershed: Fayetteville, University of 

Arkansas, unpublished M.S. thesis, 98 p.

Little, P.R., 2007, Dominant processes 

affecting groundwater quality and flow in 

Basin 2, Savoy Experimental Watershed 

(SEW): Fayetteville, University of Arkansas, unpublished M.S. thesis, 93 p.

Parse, M., 1995, Geomorphic analysis of 

the role of regolith in karst landscape 

development Benton County, Arkansas: 

Fayetteville, University of Arkansas, 

unpublished M.A. thesis, 177 p.

Pennington, D., 2010, Karst drainage-basin 

analysis using hydrograph decomposition 

techniques at the Savoy Experimental 

Watershed, Savoy, Arkansas: Fayetteville, 

University of Arkansas, unpublished M.S. 

thesis, 121 p.

Phelan, T.L., 1999, GIS and 3-D visualization 

for geologic subsurface static modeling in 

a mantled karst environment near Savoy, 

Arkansas: Fayetteville, University of 

Arkansas, unpublished M.A. thesis, 158 p.
38 Interpretation of Dye Tracing Data Collected, at the Savoy Experimental Watershed, Savoy, Arkansas

Stanton, G.P., 1993, Processes and controls 

affecting anisotropic flow in the BooneSt. Joe aquifer in northwestern Arkansas: 

Fayetteville, University of Arkansas, 

unpublished M.S. thesis, 212 p.

Ting, T.E., 2002, Development of a bacterial 

tracer for water quality studies in mantled 

karst basin using indigenous Escherichia 

coli labeled with europium: Fayetteville, 

University of Arkansas, unpublished M.S. 

thesis, 106 p.

Ting, T.E., 2005, Assessing bacterial transport, storage and viability in mantled karst 

of northwest Arkansas using clay and 

Escherichia coli labeled with lanthanideseries metals: Fayetteville, University of 

Arkansas, unpublished Ph.D. dissertation, 

279 p.

Unger, T., 2004, Structural controls influencing ground-water flow within the mantled 

karst of the Savoy Experimental Watershed, northwest Arkansas: Fayetteville, 

University of Arkansas, unpublished M.S. 

thesis, 128 p.

Vaughn, K.A., 2015, Controls on dissolution rate variation at a pair of underflowoverflow springs at the Savoy Experimental Watershed: University of Arkansas 

Theses and Dissertations 1152, 53 p., 

https://scholarworks.uark.edu/etd/1152/.

Wagner, D., 2007, In-situ assessment of 

waste storage effectiveness in karst using 

stable isotope biogeochemistry: Fayetteville, University of Arkansas, unpublished 

M.S. thesis, 58 p.

Whitsett, K.S., 2002, Sediment and bacterial tracing in mantled karst at the Savoy 

Experimental Watershed, northwest 

Arkansas: Fayetteville, University of 

Arkansas, unpublished M.S. thesis, 66 p.

Winston, B., 2006, Land use trends in areas 

underlain by karst and consequences for N 

source and processing in aquatic ecosystems: Fayetteville, University of Arkansas, unpublished M.S. thesis, 88 p.

Woodstrom, F.A., 1999, The effects of 

landuse on the spatial and temporal 

variations in the water quality of selected 

springs in Washington County, Arkansas: 

Fayetteville, University of Arkansas, 

unpublished M.A. thesis, 120 p.
Appendix 3 39

Appendix 3. Planned Agenda for Advanced Groundwater 

Field Techniques in Karst Terrains, GW2227,

November 13–17, 2017

Day 1 – Monday, Nov. 13 Classroom

Introductions 8:00–9:00 a.m. - Eve Kuniansky

Course objectives

Facilities

Savoy field site orientation

Students talk about their aquifer (Scott Prinos Biscayne 10 min.)

Karst Hydrogeology/Ozarks (30 min.) Phil Hays

Hydrogeology of Savoy site (30 min.) Van Brahana

Break 10:00–10:15 a.m.

Differential gaging (seepage runs Dan Wagner) for identifying gains and losses: use of standard gaging techniques, 

flow tracker, weirs, flumes (Dan Wagner) 

(1 hr.) 

Lunch on your own 12:00–1:00 p.m.

Borehole dye dilution techniques / flow metering in karst (30 min.) Fred Paillet

NMR borehole logging (30 min.) Sam Wallace

Surface geophysics (30 min.) Greg Stanton

Break 2:30–3:00 p.m.

Dye tracer testing in karst aquifers (30 min.) Eve Kuniansky

Geochemical tools used in karst terrain (1 hr.) Phil Hays

Introduction to temperature tracing, fiber-optic distributed 

temperature sensing (FO-DTS), vertical FO-DTS (HRTS), 

and thermal infrared (TIR) imaging

(1 hr.) Marty Briggs

Plans for Tuesday: Group assignments, overview of field 

stations, and objectives for the day

(30 min.)

Icebreaker dinner (TBD) – Dinner at restaurant next to hotel

Tracer test starts on Monday evening (10 p.m. to 2 a.m. dumping 2 or 3 different tracers (Rhodamine WT, 

Fluorescein, eosin) at three wells/sinks known to go to springs (Langle and Copperhead)—Those that 

want to participate can go with Van, Joshua, Eve, and Dan. Participation is not required.
40 Interpretation of Dye Tracing Data Collected, at the Savoy Experimental Watershed, Savoy, Arkansas

Day 2 – Tuesday, Nov. 14 Savoy Field Site

Students depart hotel; pick up lunch on the way 8:00 a.m.

Class meets at Tree Spring site for initial discussion 9:00 a.m.

Teams rotate among field stations 9:45 a.m.–Noon

Station 1: Tree Spring injection point –salt for dilution, 

measure specific conductance after each downstream 

spring

(Marty Briggs and Geoff Delin)

Station 2: Sink point on stream Phil Hays

Station 3: Langle Spring discharge point Dan Wagner – grab samples 

hourly

Station 4: Copperhead Spring discharge point Eve Kuniansky (Fluor) – grab 

samples

Station 5: Fluorometer analyses in the field Eve Kuniansky at Copperhead

Lunch near Tree Spring 12:00–1:00 p.m.

Teams continue rotating among field stations (it will be 

determined later who is where in the field)

1:00–4:00 p.m. 

Point-to-point tracer test and qualitative sampling of 

monitoring points:

Station 1: Tree Spring injection point (?)

Station 2: Sink point on stream

Station 3: Langle Spring discharge point

Station 4: Copperhead Spring discharge point

Station 5: Flurometer analyses in the field

Class meets at Tree Spring site for recap of the day's work 4:00 p.m.

Day 3 – Wednesday, Nov. 15 Savoy Field Site

Students depart hotel; pick up lunch on the way 8:00 a.m.

Class meets at Tree Spring site for initial discussion 9:00 a.m.

Teams rotate among field stations 9:30 a.m–Noon

Station 1: FLIR camera demonstration and usage Geoff Delin

Station 2: FO-DTS includes field demonstration of data 

collection, calibration, fiber choices, and splicing

Marty Briggs and Marian 

Domanski

Station 3: Sink point on stream; HRTS setup Dan Wagner – grab samples 

hourly

Lunch near Tree Spring 12:00–1:00 p.m. 

Teams continue rotating among field stations (it will be 

determined later who is where in the field)

1:00–4:00 p.m. 

Station 1: Borehole geophysical logging demonstration – 

dye dilution at one well

Fred Paillet and Greg Stanton

Station 2: Borehole geophysical logging demonstration – 

NMR tool

Sam Wallace and Jon Thomas

Station 3: Surface geophysical demonstrations (resistivity, 

GEM2, GPR)

Jason Payne

Return to hotel 4:00 p.m.
Appendix 3 41

Day 4 – Thursday, Nov. 16 Classroom

Classroom: 8:00 a.m.–Noon

Seepage-run analysis (30 min.) Dan Wagner

Dye/Salt-dilution results interpretation- interactive with 

class. 

(2 hrs.) Marty Briggs

Break 10:30–10:45 a.m.

Results of point-to-point tracer and quantitative testing (1 hr.) Joshua Blackstock and 

Eve Kuniansky

Lunch on your own 11:45 a.m.–1:00 p.m.

Classroom: Temperature analyses 1:00–5:00 p.m. 

FLIR Camera results and longitudinal DTS

1-D heat/flux model theory; 1-D TempPro (version 2) 

graphical user interface (GUI) for VS2DH numerical 

modeling approach. Upload of 1-D thermal profiles from 

Savoy site into 1-D TempPro to determine seepage direction and rates- interactive with class.

(1 hr.)

Introduction to Matlab-based VFLUX analytical modeling 

programs; analysis of similar 1-D thermal profiles from 

the Savoy stream as (a) to determine seepage rates – 

interactive with class

(1 hr.)

Group dinner TBD

Day 5 – Friday, Nov. 17 Classroom

Classroom: 8:00 a.m.–Noon

Borehole geophysical logging in karst terrain (1 hr.) Wellcad or Flash

Surface geophysical usage in karst terrain field examples/

results 

(1 hr.)

Break 10:00–10:30 a.m.

Open format discussion (1.5 hours): Synthesis of hydraulic, 

chemical, and geophysical methods for data collection in 

karst terrain. What are the relative costs and advantages 

and disadvantages of each method? Which methods are 

highly complementary? Are any methods duplicative?

(1 hr.) All instructors available

Class ends Noon

Kuniansky and others—Interpretation of Dye Tracing Data Collected November 13–December 2, 2017, at the Savoy Experimental Watershed, Savoy, Arkansas—Scientific Investigations Report 2019–5016

ISSN 2328-0328 (online)

https://doi.org/10.3133/sir20165016