Influence of Locally Derived Recharge on the 

Water Quality and Temperature of Springs in 

Hot Springs National Park, Arkansas

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2007–5004
Cover photographs: Hale Bathhouse, 2002 (top, right, photograph from the U.S. Geological Survey).

Downloading temperature data at collection box, 2002 (bottom, right, photograph from the U.S. Geological Survey).
Influence of Locally Derived Recharge 

on the Water Quality and Temperature 

of Springs in Hot Springs National Park, 

Arkansas

By Richard W. Bell and Phillip D. Hays

Scientific Investigations Report 2007-5004

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2007

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Suggested citation:

Bell, R.W., and Hays, P.D., 2007, Influence of locally derived recharge on the water quality and temperature of springs 

in Hot Springs National Park, Arkansas: U.S. Geological Survey Scientific Investigations Report 2007-5004, 45 p.
iii

Contents

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

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

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

Acknowledgments................................................................................................................................2

Overview of Geologic and Hydrologic Setting..........................................................................................4

Methods...........................................................................................................................................................4

Water-Quality..................................................................................................................................................7

Base Flow...............................................................................................................................................7

Stormflow...............................................................................................................................................8

Water Temperature of the Springs .............................................................................................................9

Influence of Locally Derived Recharge on the Water Quality and Temperature of Springs...........11

Water-Quality Data.............................................................................................................................11

Water-Temperature Data...................................................................................................................12

Isotopic and Radiochemical Data....................................................................................................15

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

Selected References...................................................................................................................................20

Figures

 1. Map showing location of study area..............................................................................................3

 2. Map showing location of sampling sites .......................................................................................5

3-9. Graphs Showing:

 3. Graph showing water temperature at hot springs equipped with continuous recorders....10

 4. Graphs showing relation between silica concentration and water temperature .................11

 5. Graph showing relation between water temperature decreases and precipitation at 

Spring 46.......................................................................................................................................13

 6. Graph showing relation between discharge and water-temperature data at the 

Hot Springs National Park spring reservoir, showing the period of record—water 

years 1991 through 2005 ............................................................................................................13

 7. Graphs showing relation between discharge and water-temperature data at the Hot 

Springs National Park spring reservoir, April 1991 ...............................................................14

 8. Graph showing relation between deuterium/hydrogen and oxygen-18/oxygen-16 

isotopic ratios..............................................................................................................................16

 9. Graphs showing relation between strontium-87/strontium-86 and strontium........................18

Tables

1. Generalized section of sedimentary rocks in the vicinity of the hot springs .........................4

 2. Information for spring and precipitation sites sampled.............................................................6

3. Nutrient, major ion, trace element, isotope, radiochemical, physical property, field 

measurement, and bacteria data for samples collected at hot- and cold-water

springs in 2000 and 2001 ............................................................................................................22
iv

4. Pesticide and semivolatile concentrations for samples collected at hot- and coldwater springs in 2000 and 2001.................................................................................................38

5. Nutrient, major ion, trace element, isotope, radiochemical, physical property, and 

field-measurement data for samples collected at hot- and cold-water springs in 

water years 1972, 2000, and 2001 .............................................................................................42

6. Temperature of selected hot springs............................................................................................9

7. Summary of statistical tests for selected constituents and physical property

differences between base-flow and stormflow samples ....................................................11

8. Cold-water fraction estimates calculated from silica and total dissolved solids data for

base-flow and stormflow conditions.......................................................................................12

Conversion Factors, Vertical Datum, and Abbreviations

Multiply By To obtain

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

square foot (ft2) 0.0929 square meter (m2)

square mile (mi2) 2.590 square kilometer (km2)

cubic foot (ft3) 7.481 gallon (gal)

Temperature in degrees Celsius (  ̊C) may be converted to degrees Fahrenheit ( ̊F) as follows:  ̊F = (1.8 x  ̊C) + 32

In this report, horizontal coordinate information is referenced to the North American Datum of 1927 (NAD 27).

Water year is the 12-month period October 1 through September 30.

Abbreviations and Acronymns Used in this Report

mg/L, milligrams per liter

mBq/L, milli-Becquerels per liter

pCi/L, picocuries per liter

mg/L, microgram per liter

mS/cm, microsiemens per centimeter at 25 degrees Celsius

‰, parts per thousand (per mil)

HNSP, Hot Springs National Park

MRL, method reporting limit

MCL, maximum contaminant level

SVOC, semivolatile organic compounds

TDS, total dissolved solids

VSMOW, Vienna Standard Mean Ocean Water
Influence of Locally Derived Recharge on the Water 

Quality and Temperature of Springs in Hot Springs 

National Park, Arkansas

By Richard W. Bell and Phillip D. Hays

Abstract

The hot springs of Hot Springs National Park consist of 

a mixture of water from two recharge components: a primary 

hot-water component and a secondary cold-water component. 

Widespread distribution of fractures enables mixing of the hotand cold-water components of flow near the discharge area 

for the springs. Urbanization in the area near the hot springs 

of Hot Springs National Park has increased the potential for 

degradation of the quality of surface-water runoff and locally 

derived ground-water recharge to the hot springs. Previous 

studies by the U.S. Geological Survey have indicated that 

water from some cold-water springs and wells in the vicinity 

of Hot Springs, Arkansas, showed evidence of contamination 

and that water from locally derived cold-water recharge might 

contribute 25 percent of the total flow to the hot springs after 

storms.

Water samples were collected during base-flow conditions at nine hot springs and two cold-water springs in 

September 2000. Nine hot springs and one cold-water spring 

were resampled in October 2001 after a storm that resulted 

in a measurable decrease in water temperature in selected 

hot springs. Water samples were analyzed for a variety of 

dissolved chemical constituents (nutrients, major ions, trace 

elements, pesticides, semivolatile compounds, isotopes, and 

radiochemicals), physical properties, field measurements, and 

bacteria. 

Comparison of analyses of samples collected during 

base-flow conditions from the springs in 2000 and during a 

storm event in 2001 with the results from earlier studies dating 

back to the late 1800’s indicates that little change in major, 

minor, and trace constituent chemistry has occurred and that 

the water continues to be of excellent quality. 

Water-quality data show distinguishable differences in 

water chemistry of the springs during base-flow and stormflow 

conditions, indicating changing input of cold-water recharge 

relative to hot-water recharge. Silica, total dissolved solids, 

strontium, barium, and sulfate show statistically significant 

differences between the median values of base-flow and 

stormflow samples. While variations in these constituents do 

not degrade water quality, the differences do provide evidence 

of variability in the factors controlling water quality of the 

hot springs and show that water quality is influenced by the 

locally derived, cold-water component of flow to the springs.

Water temperature was measured continuously (3-minute intervals) between August 2000 and October 2002 at four 

hot springs. Continuous water-temperature data at the springs 

provide no indication of persistent long-term change in water 

temperature through time. 

Short time-scale water-temperature decreases occur in 

response to mixing of hot-springs water with locally derived 

recharge after storm events; the magnitude of these decreases 

varied inversely with the amount of rainfall. Maximum 

decreases in water temperature for specific storms had a nonlinear relation with the amount of precipitation measured for 

the events.

Response time for water temperature to begin decreasing 

from baseline temperature as a result of storm recharge was 

highly variable. Some springs began decreasing from baseline temperature as quickly as 1 hour after the beginning of a 

storm; one spring had an 8-hour minimum response time to 

show a storm-related temperature decrease.

Water-quality, water-temperature, isotopic, and radiochemical data provide multiple lines of evidence supporting 

the importance of the contribution of cold-water recharge to 

hot springs. All the springs sampled indicated some measure of influence from local recharge. Binary mixing models 

using silica and total dissolved solids indicate that coldwater recharge from stormflow contributes an estimated 10 

to 31 percent of the flow of hot springs. Models using water 

temperature indicate that cold-water recharge from stormflow 

contributes an estimated 1 to 35 percent of the flow of the various hot springs. Although these data indicate that cold-water 

recharge from stormflow does contribute to the flow of the hot 

springs, data from additional stormflow events and also from 

additional hot springs are needed to rigorously define the variability and contribution of cold-water recharge.
Introduction

The hot springs of Hot Springs National Park (HSNP), 

located in Hot Springs, Arkansas (fig. 1), have been a natural 

resource of international renown and popular utility for many 

years. The first scientific study of the springs was initiated by President Thomas Jefferson in 1804; a later request 

for efficacious use and proper management of the springs 

resulted in creation of the Hot Springs Reservation in 1832 

and designation as a federally managed national park in 1921. 

The national park designation serves to preserve and protect 

the natural and cultural resources of the area for present and 

future generations.

The hot springs are valued as a source of drinking water 

and for the recreational and therapeutic benefits of the hot 

water baths. In 2002, about 1.4 million people made recreational visits to HSNP, more than 100,000 people bathed in 

the hot waters, and additional tens of thousands of people 

collected water for drinking (D. East, National Park Service, 

oral commun., 2003). 

Urbanization in the area near the hot springs has 

increased the potential for degradation of the quality of surface-water runoff and locally derived ground-water recharge 

to the springs (Hansen and Gryskiewicz, 2003). Potential 

degradation of runoff and recharge may result from contaminants leaking from sewer systems and underground storage 

tanks, contaminants from chemical-intensive commercial 

activities where spills or improper disposal may occur, and 

contaminants from nonpoint source runoff such as lawns, 

parking lots, and roads. Because of the increased vulnerability of the hot springs as the area near the HSNP undergoes 

development, the National Park Service’s (NPS) Resources 

Management Plan includes a section stating that the Park was 

created to provide hot water to the public and that protecting 

the hot-water resource is an important resource-management 

goal (National Park Service, 1998).

Previous studies (Bedinger and others, 1979; C.S. Barks, 

U.S. Geological Survey, written commun., 1995) conducted 

by the NPS and the U.S. Geological Survey (USGS) have 

indicated that much of the water issuing from the hot springs 

is approximately 4,400 years old and for the next four 

millennia this component of flow is unlikely to show any 

deterioration in water quality resulting from development and 

urbanization of the area near the Park. However, these same 

studies have indicated that an unquantified component of flow 

from the springs is of recent origin; this component of flow is 

derived from a recharge area that contributes relatively cold 

water to the hot springs. The recharge area for the cold-water 

component of recharge is (1) probably not contiguous with 

the hot-water recharge area with the cold-water component 

following a very different, shallower, flowpath, (2) likely of 

limited areal extent, and (3) probably located near the discharge area of the springs.

The most comprehensive previous study of the hot 

springs (Bedinger and others, 1979) provided evidence that 

the hot springs consist of a mixture of water from two 

sources: a primary source about 4,400 years old and a secondary source less than 20 years old. In addition, the study 

indicated that a component of flow to some cold-water 

springs and wells in the Hot Springs area showed evidence 

of contamination, such as elevated concentrations of nitrate 

and chloride. Water temperature and flow data collected by 

the USGS in the mid-1990’s at the HSNP spring reservoir 

(C.S. Barks, U.S. Geological Survey, written commun., 

1995) indicated that a storm event strongly affected hot 

springs discharge and temperature. Data from this study 

indicated that water from locally derived recharge areas 

might contribute 25 percent of the total flow to the hot 

springs after such a storm.

The results of these two studies suggest the potential 

for degradation of water quality in the hot springs by locally 

derived recharge, which could have important ramifications 

for public health and for management of the hot springs 

water resource. However, water quality and the presence of 

contaminants in the locally derived component of the hot 

springs have not been adequately characterized for either 

base-flow or stormflow conditions.

Purpose and Scope

The purpose of this report is to identify any influence 

of locally derived recharge on the water quality and temperature of hot springs. Information includes (1) water-quality data from nine hot springs and two cold-water springs 

sampled in 2000 and 2001 for comparison with water-quality and temperature measurements from previous studies of 

the hot springs and (2) characterization of the variability of 

water temperature for the hot springs. For the water-quality component of the study, samples from springs were 

collected in 2000 during base-flow conditions; additional 

samples, from the same springs, were collected in 2001 during stormflow conditions. To describe variability of water 

temperature, data from temperature recorders deployed at 

four hot springs were evaluated. To describe the influence 

of locally derived recharge on the hot springs, differences in 

concentrations of selected chemical constituents, isotopes, 

physical properties, and field measurements were evaluated 

for the base-flow samples and stormflow samples. 

Acknowledgments

The assistance of Steve Rudd of HSNP is gratefully 

acknowledged. His knowledge of the springs and cooperation in providing access to spring boxes and bathhouses 

streamlined sample-collection activities. Marsha Gipson and 

Rene Freret of the USGS installed and maintained temperature recorders. Kenny Knox of the Hot Springs Fire Department provided information about rainfall events. We also 

thank Jerome and Betty Whipple for providing access to the 

ArScenic cold-water spring.

 Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Figure 1. Location of study area (sampling locations are shown on figure 2).

Lake

Hamilton

Bull

Gulpha

Gulpha

Creek

Hot Springs Cr

Springs

Creek

Hot

Creek

Middle

Branch

Whittington Creek

Bayou

ArScenic

Spring

Happy Hollow

Spring

Grand

Avenue

Grand

Avenue

Black Snake Road

Park

Cedar

Glades

Road

City

Square

7

7

270

70

Avenue

Avenue

Whittington

One way

0 1 MILE

0 1 KILOMETER

34 ̊32'30"

93 ̊05' 93 ̊

34 ̊30'

Sugarloaf Mountain

West Mountain

North Mountain

Hot Springs

Mountain

City of

Hot Springs

Arkansas Valley

Ouachita Mountains

Hot Springs

Ozark Plateaus

Mississippi

Alluvial

Plain

West Gulf

Coastal

Plain

36 ̊

35 ̊

34 ̊

93 ̊ 94 ̊ 92 ̊ 91 ̊

90 ̊

MISSOURI

OKLAHOMA

TEXAS

LOUISIANA

MISSISSIPPI

TENNESSEE

Mississippi

River

INTERIOR

COASTAL

PLAIN

HIGHLANDS

Study area

Location

Map

Hot Springs National Park

Hot springs discharge area (fig. 2)

EXPLANATION

Introduction 
Overview of Geologic and Hydrologic 

Setting

This section of the report provides a brief description of 

the geology and hydrology affecting the hot springs at HSNP. 

For a more detailed review of the geology and hydrology, the 

reader is referred to the discussions in Bedinger and others 

(1979). 

The rocks cropping out in the vicinity of the hot springs 

are primarily sedimentary rocks of Paleozoic age (table 1). 

Shale, sandstone, chert, and novaculite predominate in local 

outcrops. Rocks in the Hot Springs area have undergone at 

least three episodes of compressional deformation. These 

deformation episodes resulted in a series of thrust faults and 

overturned complexly folded anticlines trending in a northeast-southwest direction.

Table 1. Generalized section of sedimentary rocks in the vicinity of 

the hot springs.

[o, outcrops in the vicinity of Hot Springs National Park; modified after Bedinger 

and others, 1979]

System Formation

Maximum

 thickness in

Hot Springs area

(feet)

Mississippian

Stanley Shale (o) 8,500

Hot Springs Sandstone (o) 150

Arkansas Novaculite (o) 650

Devonian

Silurian Missouri Mountain Shale, (o)

Blaylock Sandstone, and

Polk Creek Shale, undifferentiated

195

Ordovician

Bigfork Chert (o) 700

Womble Shale 1,500

The hot waters are thought to enter the ground-water 

system, within a few tens of miles of HSNP, as meteoric 

water from a recharge area in the fractured, highly permeable Bigfork Chert and Arkansas Novaculite that outcrop in 

exposed anticline structures to the west, north, and northeast 

of the hot springs discharge area. The waters migrate to estimated minimum depths of 4,400 to 7,500 ft, at which depths 

a geothermal temperature gradient between 0.006  ̊C/ft and 

0.01  ̊C/ft, would allow the water to achieve the high temperatures in the deep section of the flow path before passing 

through fault and fracture conduits in the relatively impermeable shales of the Polk Creek and Missouri Mountain Shale. 

The hot waters reemerge through the Hot Springs Sandstone 

between the traces of two thrust faults, along several northeasttrending lineaments (Bedinger and others, 1979).

The locally derived, cold-water component of flow in the 

hot springs is probably similar in origin to water in cold-water 

wells that tap shallow ground water in the area and to water 

emerging from cold-water springs common in the immediate area of HSNP. Spring resurgence zones are areas where 

hydrogeologic conditions—structural, stratigraphic, petrologic, and hydrologic influences on permeability distribution 

and permeability contrasts—cause convergence of groundwater flow lines and integration of ground-water flow. Rocks 

that carry the cold-water component of flow in the Hot Springs 

area are extensively fractured, allowing water to move rapidly 

through fracture conduits in the rock. The widespread distribution of fractures enables integration and mixing of the hot- and 

cold-water components of flow in the resurgence zone; mixing 

probably occurs where the hot waters emerge from the deep 

portion of the flow path into the shallow ground-water zone 

(Bedinger and others, 1979).

Methods

Water samples were collected from 11 springs in the 

study area (figs. 1 and 2; table 2) in September 2000 and 10 

of the springs were resampled in October 2001. The springs 

were selected for sampling based on several criteria: sufficient flow, accessibility, and location—springs located 

along Central Avenue and east of the promenade (fig. 2) were 

included to monitor variability related to elevation. Spring 

numbers and names in table 2 have the same nomenclature 

used by Bedinger and others (1979). A precipitation sample 

also was collected in October 2001. Of the 11 samples collected in 2000, 9 hot springs and 2 cold springs were analyzed 

for a broad suite of chemical constituents, physical properties, 

field measurements, and bacteria (tables 3, 4, and 5 (located 

at the end of the report)). All nine hot springs and one cold 

spring were resampled in October 2001. The September 2000 

samples were collected during base-flow conditions; the October 2001 samples were collected after a storm that resulted in 

a measurable decrease in water temperature in four selected 

hot springs equipped with continuous temperature recorders. As part of the stormflow sampling effort, a precipitation 

sample was collected at the NPS meteorological station near 

Hot Springs Mountain Drive; the sample was analyzed for 

sulfate and the following isotopes: sulfur-35 (35S), deuterium 

(

2

H), and oxygen-18 (18O).

Water-quality samples were collected using USGS lowlevel techniques (Koterba and others, 1995). Analyses for 

nutrients, major ions, trace elements, semivolatile compounds, 

and pesticides were performed at the Severn Trent Laboratory 

in Denver, Colorado; analyses for radiochemicals and isotopes 

were performed at USGS Water Resources Discipline Laboratories in Reston, Virginia, and Menlo Park, California.

 Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
CB2

Reserve Avenue

Central Avenue

Promenade

N

Promenade

Hot Springs Creek (underground) Bathhouse Row Fountain Street Hot-water spring—Sampled (number refers to station number in table 2)

Hot-water spring—With temperature probe  (number refers to station number in table 2)Hot-water spring—Not sampledCollection box and numberValve boxPrecipitation collection siteObservation well and numberCollection system pipe to reservoirDrainage to Hot Springs Creek

Modified from Bedinger and others (1979)

Hot Springs Mountain Drive

EXPLANATION

00

500 FEET

150 METERS

250

75

1

47

48

3

5 8

7 10

12

14 16

49 20 22

21C

23 24

31

33

33

32

34

35

26

21

29 27

30

28

50

2

4/4a

6 6c 6a

6b

9a 9 11 13

17 18

36

37

39

40

41

38

43

43a

19

15

25

46

42

W3

W2

W5

W4

W1

CB4

CB3

CB5

CB1

Superior

Arlington Hotel

Hale

Maurice

Fordyce Quapaw

Ozark

Buckstaff

Lamar

Cooling

system

W3

T

T

T

T

Administration Spring

reservoir

46 T

CB2

Toilet

Drain

38

Figure 2. Location of sampling sites.

Methods 
Table 2. Information for spring and precipitation sites sampled.

[N, no; Y, yes]

Station number Spring number or site name

Type of

spring Latitude Longitude

Sampled

in 2000

Sampled

in 2001

Continuous

temperature

recorder

343058093030901 Spring 47 hot 343058 0930309 Y Y N

343056093030901 Spring 8 hot 343056 0930309 Y Y Y

343054093031201 Spring 49 hot 343054 0930312 Y Y N

343057093031301 Spring 17 hot 343057 0930313 Y Y Y

343055093031301 Spring 9 hot 343055 0930313 Y Y N

343052093031301 Spring 25 (Hale Bathhouse) hot 343052 0930313 Y Y Y

343050093031201 Spring 33 (Upper Display Spring) hot 343050 0930312 Y Y N

343049093031301 Spring 46 (Fordyce Bathhouse) hot 343049 0930313 Y Y Y

343048093031301 Spring 42 (Quapaw Bathhouse) hot 343048 0930313 Y Y N

343130093021901 ArScenic Spring cold 343130 0930219 Y N N

343110093025301 Happy Hollow cold 343110 0930253 Y Y Y

343051093030601 Precipitation site -- 343051 0930306 N Y N

Temperature probes and recorders were used to monitor water temperature in four hot springs and one cold-water 

spring (table 2). Temperature probes capable of measuring 

water temperatures between -40 and 100  ̊C were deployed in 

the springs and bathhouses. In spring boxes, the probes were 

anchored with a stainless-steel weight in the mouth of the 

collection pipe approximately 0.4 ft below the water surface. 

In bathhouses, the temperature probes were suspended below 

the water surface from tiles adjacent to the spring channel. 

Monitors that recorded water temperature at 3-minute intervals 

in the spring collection boxes and bathhouses were activated in 

August 2000.

A monitoring station located in the basement of the park 

administration building has been monitoring spring reservoir 

(fig. 2) discharge from October 1988 through June 2005 and 

temperature from October 1990 through June 2005. The monitoring station consists of a weir to measure the inflow from 

the collection system to the collection reservoir; a float device 

to measure the water level in the reservoir; a weir to measure 

the overflow from the reservoir to Hot Springs Creek; and a 

temperature probe located at the inflow weir to measure water 

temperature from the thermal springs. The inflow and overflow weirs were identical in design and construction and were 

installed side by side, but were oriented in opposite directions 

and at different elevations. The weirs were calibrated in a 

flume for discharges from 0.01 to 2.12 cubic feet per second 

(ft3/s), or 4.5 to 952 gallons per minute (gal/min), and rating 

equations were established to convert the water level in the 

weir boxes to discharge of water passing through the weirs. 

The water levels in the weirs and the reservoir were measured 

to one-hundredth of a foot, and the temperature measured to 

one-hundredth of a degree Celsius. All data were recorded at 

15-minute intervals and transmitted every 4 hours. The methods used for measuring discharge followed Rantz and others, 

(1982), and the methods used for measuring temperature followed Wagner and others (2000).

The total discharge of the thermal springs for the period 

from October 1990 through June 2005 was determined by 

adding the total inflow to the collection reservoir and the 

estimated discharge from springs 43 and 43a that emerge from 

the open bottom of the collection reservoir. The discharge 

from springs 43 and 43a was estimated from three reservoir 

recovery tests conducted in 1989 (C.S. Barks, U.S. Geological Survey, written commun., 1989). The tests were conducted 

by diverting collection-system inflow to Hot Springs Creek 

and pumping down the water in the reservoir, allowing only 

springs 43 and 43a to discharge into the reservoir. The total 

discharge of springs 43 and 43a were calculated from the 

recovery of the reservoir water level.

Amounts of precipitation and storm, start-time data were 

obtained from automated precipitation gages located in various parts of Hot Springs, Arkansas, and the precipitation site 

near Hot Springs Mountain Drive. The precipitation gages are 

operated by the Hot Springs Fire Department; the precipitation 

site is operated by the NPS.

Descriptive statistics are used to show the central tendency and variation in the data. The minimum, maximum, 

and median (50th percentile) are presented for the nine hot 

springs. Statistical tests (t-test and rank sum test) were used to 

evaluate statistically significant differences (p-values less than 

0.05) between the median values of base-flow and stormflow 

samples for several constituents and physical properties. 

 Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Binary mixing models are used to estimate the contribution of cold-water recharge to the hot springs. To calculate 

proportions of components involved in a mixture, the binary 

mixing equation (1) was used (Faure, 1977).

X X f X f mix A A B B = + ( ) ( ) (1)

where

 Xmix is the species concentration or isotopic 

composition of the mixture,

	 XA is species concentration or isotopic composition 

of a component A contributing to a 

mixture,

f

A is the fraction of component A present in the mix,

XB is the species concentration or isotopic 

composition of a component B 

contributing to a mixture, and

f

B is the fraction of component B present in the mix 

and is equal to 1-fA.

Many of the water-quality constituents from samples collected had “non-detected” concentrations. The concentrations 

reported for these constituents were variable, depending on the 

method used to perform the analysis for a specific constituent. The lower limits below which constituent concentrations 

cannot be measured within specified accuracy constraints were 

set by the threshold of laboratory analytical techniques and 

equipment. When the measured concentration of a constituent 

was less than this lower limit, the concentration was reported 

as less than or “below” the method-reporting limit (MRL). In 

some cases the laboratory might be confident that a value less 

than the MRL is “real”; these results are indicated as “estimated”.

Water-Quality

As a unique water resource for drinking and primary contact such as bathing, the status of water quality and an understanding of changes in water quality through time for the hot 

springs are of critical importance. This importance and need 

for knowledge are heightened by evolving land use and urbanization in the hot-spring recharge and discharge areas. The 

following sections summarize the results of the water-quality 

analyses for samples collected during base flow and stormflow 

for a variety of constituents (nutrients, major ions, trace elements, field measurements, bacteria, and physical properties 

including water temperature). The results of the base-flow and 

stormflow samples are compared with water-quality data collected from previous investigations.

Water from the hot springs contains a variety of dissolved 

chemical constituents. Knowledge of the chemical types and 

concentrations can be used to interpret ground-water movement, source of the water, and temporal changes in chemical 

concentration (Bedinger and others, 1979). Comparison of 

analyses of samples collected from the springs during 2000 

and 2001 with the results from earlier studies dating back to 

the late 1800’s shows that little change in major, minor, and 

trace constituent chemistry has occurred and that the water 

continues to have excellent quality. Minor differences are 

apparent (silica, zinc, and nutrient concentrations) that may 

be a result of sampling different springs, plumbing modifications (engineered collection and distribution infrastructure), 

different analytical techniques, and the natural geochemical 

differences characteristic of most ground-water systems. 

Base Flow

During base-flow conditions, with sampling being conducted near the end of the summer-fall dry season, concentrations of nutrient, major ion, trace element, pesticide and 

semivolatile compounds, as well as stable isotope, radiochemical, physical property, field measurement, and bacteria data 

were collected at nine hot springs and two cold springs. No 

constituents from the samples collected during the base-flow 

sampling event exceeded their respective drinking-water, maximum contaminant levels (MCL) set by the U.S. Environmental Protection Agency (U.S. Environmental Protection Agency, 

2003) (table 3, located at end of report). The samples collected 

for the base-flow sampling event were collected following 

seasonal hydrologic conditions that were similar to conditions 

preceding the collection of samples reported by Bedinger and 

others (1979) in that no precipitation had occurred in the week 

prior to sampling.

Concentrations of five nutrient compounds (nitrogen 

ammonia; nitrogen nitrate; nitrite plus nitrate; phosphorus; 

orthophosphorus) were measured in hot-spring, base-flow 

samples. The concentrations generally were less than 0.5 mg/L 

and concentrations in many samples were below the MRL for 

the compound. The nutrient concentrations measured for the 

hot springs were comparable to those reported by Bedinger 

and others (1979) for samples collected in January 1972—no 

nitrate, ammonia, or organic nitrogen concentrations for 

samples collected in 1972 from the hot springs exceeded their 

respective 1972 MRL’s. The nutrient concentrations measured 

in samples from the two cold springs also were less than 0.5 

mg/L. These low concentrations were similar to concentrations 

reported by Bedinger and others (1979) for cold-water springs 

and wells in the vicinity of HSNP.

Concentrations of eight major ions were measured in 

hot-spring, base-flow samples (table 3). Concentrations were 

less than MRL’s for samples analyzed for potassium, sodium, 

chloride, and fluoride. The major ions having the highest concentrations in the hot springs were calcium (47.9 mg/L) and 

silica (46.9 mg/L). Most of the major ion concentrations measured for the hot springs were comparable to those reported by 

Bedinger and others (1979) for samples collected in January 

1972. Silica concentrations reported by Bedinger and others 

(1979) for the hot springs were smaller than those determined 

for base-flow samples in this study. Analyses for silica in hot 

Water-Quality Concentrations 
spring samples collected in 1972 (Bedinger and others 1979) 

were very consistent, ranging from 41 to 42 mg/L. A maximum concentration of 42 mg/L and a median concentration 

of 42 mg/L were reported in 1972. Results from the base-flow 

sampling at the hot springs conducted in 2000 markedly were 

different. Silica concentrations were more variable, ranging 

from 40.8 to 46.9 mg/L and exhibited a median value of 44.9 

mg/L. Comparison of calcium and sulfate results shows that 

samples collected during the 2000 base-flow sampling event 

exhibited dissolved calcium concentrations ranging from 38.9 

to 47.9 mg/L and dissolved sulfate concentrations ranging 

from 7.0 to 7.5 mg/L as compared with concentrations ranging 

from 44 to 45 mg/L and from 7.8 to 9.0 mg/L, respectively as 

reported by Bedinger and others (1979). 

Concentrations of 23 trace elements were measured in 

the base-flow samples (table 3). Trace element concentrations 

for 18 of the elements analyzed were less than MRL’s for the 

hot-spring, base-flow samples. The trace elements having the 

highest concentrations in the hot springs were manganese (231 

μg/L), barium (141 μg/L), and strontium (110 μg/L). The concentrations of trace elements in samples collected in 2001 are 

similar to the concentrations reported in Bedinger and others 

(1979). 

Concentrations of 82 pesticides and semivolatile organic 

compounds (SVOC) were measured in base-flow samples 

collected at two hot springs (Springs 9 and 49) and one coldwater spring (ArScenic) (table 4, located at end of report). 

No concentration for any pesticide or SVOC exceeded its 

MRL. No pesticide or SVOC samples were collected for the 

Bedinger and others (1979) study.

Nine physical properties and bacteria concentrations were 

measured in hot-spring, base-flow samples (table 3). Total 

dissolved solids (TDS) concentration ranged from 177 mg/L 

to 207 mg/L. The pH values ranged from 6.5 to 7.8. Specific 

conductance ranged from 267 μS/cm to 296 μS/cm. Water 

temperature ranged from 54.2°C to 63.7°C. Alkalinity (as 

CaCO3) ranged from 118 mg/L to 128 mg/L. Alkalinity (as 

HCO3) ranged from 144 mg/L to 156 mg/L. Escherichia coli

(E. coli) were detected in base-flow samples from Spring 8 

(120 colonies/100 mL of water) and ArScenic spring (12 colonies/100 mL of water). Detections of fecal coliform indicator 

bacteria also were found at Spring 8 (200 colonies/100 mL of 

water) and ArScenic spring (74 colonies/100 mL of water). 

Some physical property values for base-flow samples collected 

in 2000 vary slightly from values of samples collected in 1972 

as reported by Bedinger and others (1979). Bedinger and others (1979, selected springs are shown in table 5, located at end 

of report) reported pH values ranging from 6.9 to 7.7, specific 

conductance ranging from 266 to 276 mS/cm, and TDS concentrations ranging from 184 to 189 mg/L.

The alkalinity (as HCO3) concentrations reported by 

Bedinger and others (1979) for the hot springs differed considerably from those determined for base-flow samples in this 

study. The alkalinity (as HCO3) concentrations for the hot 

springs reported by Bedinger and others (1979) ranged from 

155 to 165 mg/L, whereas alkalinity (as HCO3) concentrations 

measured in the base-flow samples for 2000 and 2001 (table 

3) ranged from 144 to 156 mg/L. The difference might have 

been because of sampling differences, such as filtered water 

compared to whole water or difference in season and hydrologic conditions. 

Stormflow

During stormflow conditions, nutrient, major ion, trace 

element, isotope, radiochemical, physical property, field 

measurement, and bacteria data were collected at nine hot 

springs and one cold spring. No constituents from the samples 

collected during stormflow exceeded their respective drinkingwater MCL’s set by the U.S. Environmental Protection Agency 

(U.S. Environmental Protection Agency, 2003).

Concentrations of five nutrient compounds were measured in hot-spring, stormflow samples (table 3). The concentrations generally were less than 0.5 mg/L and concentrations 

in many samples were below the MRL for the compound. The 

concentrations of two nitrogen and one phosphorus compound 

were low—values for all the analyses were less than 1 mg/L 

and concentrations in most samples were below the MRL for 

the compound.

Concentrations of eight major ions were measured in 

hot-spring stormflow samples (table 3). Concentrations were 

less than MRL’s for samples analyzed for potassium, sodium, 

chloride, and fluoride. The constituents having the highest 

concentrations in the hot springs were calcium (41.9 mg/L) 

and silica (38.7 mg/L). 

Concentrations of 23 trace elements were measured in 

hot-spring, stormflow samples (table 3). Concentrations were 

less than MRL’s for samples analyzed for 16 trace elements. 

The trace elements having the highest concentrations in the 

hot springs were manganese (261 μg/L), iron (208 μg/L), and 

barium (156 μg/L). 

Concentrations of 82 pesticides and SVOC’s were 

measured in stormflow samples collected at two hot springs 

(Springs 9 and 49) and one cold spring (Happy Hollow) (table 

4). No concentration for any pesticide or SVOC exceeded its 

MRL.

Nine physical properties and field measurements and bacteria concentrations were measured in hot-spring stormflow 

samples. Values and summary statistics of these measurements 

are shown in table 3. Most values are similar to their baseflow counterparts. Detections of E. coli bacteria were found 

in the sample from Spring 33 (25 colonies/100 mL of water). 

Additional samples would be required for comparison with 

the MCL for total coliform bacteria (including fecal coliform 

and E. coli) set at more than 5 percent samples total coliformpositive in a month (U.S. Environmental Protection Agency, 

2003). A possible source of the bacteria was runoff from the 

hillside above spring 33. No detections of fecal coliform indicator bacteria were found in the stormflow samples. 

 Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Water Temperature of the Springs 9

Water Temperature of the Springs

As one of the fundamental water-quality characteristics 

and the characteristic of primary interest for this resource, a 

long history of temperature data exists for the hot springs. The 

first recorded measurement of water temperature for the hot 

springs at HSNP was made by William Dunbar and George 

Hunter for a scientific investigation requested by President 

Thomas Jefferson in 1804; a maximum spring temperature of 

67.8°C was measured during this study (Weed, 1902). Owen 

(1860) reported a maximum temperature of 64.4°C. The same 

year, Glascow (1860) reported a maximum temperature of 

65.6°C. Bedinger and others (1979) measured a maximum 

temperature of 61.8°C (Spring 49) in 1972. The maximum 

temperature for the current study, measured in conjunction 

with the collection of the water-quality samples during base 

flow, was 63.7°C (Springs 9 and 25). Temperatures for springs 

that have water-temperature measurements from several previous studies are listed in table 6. 

Water-temperature data at the hot springs do not indicate long-term change in temperature through time, perhaps 

with the exception of Spring 42. Bedinger and others (1979) 

calculated a slight decrease in maximum water temperature 

(0.6°C per 10 years) in 12 hot springs measured between 1890 

and 1952 in comparison with water temperatures measured in 

1952 (table 6; Kuroda, 1953), but noted that the data did not 

necessarily support the existence of a trend “because of differences in sampling points, variations in temperature with flow 

rates, and variations in temperatures owing to air temperature.” 

The factors controlling final temperature of the hot waters at 

the discharge points, for example air temperature, engineered 

spring collection and routing infrastructure, and short flow 

path cold-water recharge contribution, are variable and make 

direct comparison of temperature measurements difficult. 

Water temperature was measured continuously (3-minute 

intervals) during the current study between August 2000 and 

October 2002 at four hot springs (Springs 8, 17, 25, and 46) 

and one cold spring (Happy Hollow); a single-point measurement was taken at all sampled springs as part of the base-flow 

and stormflow sampling events. The continuous water-temperature data collected for the current study are the first and only 

data of this type available for the Hot Springs system. 

Base flow (excludes “storm events”) water temperatures 

(fig. 3) between August 2000 and June 2005 for the continuously measured springs typically ranged from about 63.0°C 

to 63.5°C (Spring 25), 60.0°C to 62.0°C (Spring 8), 54.5°C 

to 57.0°C (Spring 46), and 54.0°C to 54.5°C (Spring 17). The 

higher temperatures for these four springs generally occurred 

during the summer months and the lower temperatures (for 

base-flow conditions) occurred during the winter months; 

Spring 25 exhibits an offset delay of approximately 3 months 

potentially because of a deeper, more insulated flow path and 

minimal local, cold-water contribution. These data, similar 

to data presented in previous investigations, indicate that seasonal temperature fluctuations of the springs are influenced by 

air temperature.

 As hot waters move from depth to the surface discharge 

points at the springs, some decrease in the maximum temperatures attained by these waters at depth may be expected. A 

technique for estimating water temperature at depth is to use 

silica concentration as a chemical thermometer (Fournier and 

Rowe, 1966). The silica concentration of water discharging at 

Table 6. Temperature of selected hot springs.

[modified after Bedinger and others (1979); units in degrees Celsius]

Year of measurement

Site name 18901 19002 19012 19313 19524 19725 2000

Spring 1 62.6 61.9 61.7 -- 62.0 54.6 --

Spring 17 -- 55.4 56.4 55.6 56.9 56.0 54.2

Spring 23 -- 62.0 62.4 50.0 59.6 56.2 --

Spring 42 (Quapaw bathhouse) 51.6 -- 58.3 60.6 60.8 61.3 61.9

Spring 46 (Fordyce bathhouse) -- 51.5 -- 57.2 -- 58.3 55.7

1

Branner, 1892.

2

Haywood, 1902.

3

Hamilton, 1932.

4

Kuroda, 1953.

5

Bedinger and others, 1979.
1/1/01 1/1/02 1/1/03 1/1/04 1/1/05

HOURLY MEAN WATER TEMPERATURE, IN DEGREES CELSIUS

48

50

52

54

56

58

60

62

64

66

Spring 8

Spring 17

Spring 25

Spring 46

Figure 3. Water temperature at hot springs equipped with continuous recorders.

the surface can be used to determine the subsurface temperature 

of the water when it was last at equilibrium with solid siliceous 

phases. Silica minerals exhibit increased solubility at higher 

temperatures. While dissolution of silica occurs at a relatively 

rapid rate, precipitation induced by any decrease in temperature 

is kinetically inhibited and often occurs more slowly from a 

resultant supersaturated solution. As the hot waters at HSNP 

move towards the surface and begin cooling, original silica 

concentrations are maintained, and the waters become supersaturated at the new, lower temperature. The degree of supersaturation can be used to calculate the maximum temperature that the 

water has attained on its flow path. The assumptions used for 

this method of estimating maximum water temperature are 

(1) that the water reached thermal dynamic equilibrium with 

respect to dissolved silica and the parent mineral phases, (2) the 

parent mineral phase for hot springs flow system was chalcedony (a cryptocrystalline quartz mineral composing the primary 

mineralogy of the Bigfork Chert and Arkansas Novaculite), and 

(3) no substantial amount of silicate precipitation occurred in the 

water before sampling at the hot spring sources.

Samples collected in 1972 (Bedinger and others, 1979) for 

the most part have silica concentrations that are between the values for base-flow and stormflow samples collected in September 

2000 and October 2001; the concentrations for the samples 

collected in 1972 are closer to the 2000 base-flow values than 

to the 2001 stormflow values (table 5). The samples collected in 

January 1972 were collected following precipitation conditions 

that were similar to the precipitation conditions preceding the 

collection of base-flow samples collected in September 2000.

The higher average silica concentrations for the samples 

collected during base flow in 2000 indicate that the maximum 

temperature of the water traveling on the deep flow path may 

be higher than previously calculated. Bedinger and others 

(1979) used the approach of Fournier and Rowe (1966) to 

calculate the maximum temperature reached by the water. 

The same calculation and assumption of aquifer composition 

predominated by chalcedony were used with silica data from 

the base-flow samples collected in 2000. These estimated 

temperatures are the result of mixtures of waters from different depths and flow paths and of different temperatures. Based 

on the maximum silica concentration from base-flow data 

collected in 2000 (seen at spring 47, table 3), the maximum 

temperature is approximately 66.6°C. This temperature is

3.4°C higher than the source temperature of 63.2°C (based on 

a silica concentration of 41.5 mg/L) calculated by Bedinger. 

This difference is potentially explained by the timing of the 

sampling in 1972 (Bedinger and others, 1979): hot-spring 

samples were collected during January, when shallow groundwater levels usually are highest and short-flow path recharge 

having low-silica concentrations should be expected to be a 

more important component of total flow than during summer, 

when shallow ground-water levels are lowest, and therefore 

the high-silica thermal water has a larger impact. This conclusion is supported by stormflow silica concentration data 

collected in 2001. During the stormflow sampling (a time 

10 Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Influence of Locally Derived Recharge on the Water Quality and Temperature of Springs 11

when short-flow path recharge is greatest), the median silica 

concentration was 8.6 mg/L less than during the base-flow 

sampling (table 3, fig. 4).

to the springs. This younger, locally derived component of 

flow is possibly susceptible to surface influences associated 

with urbanization and changing land use that might introduce 

contaminants into the thermal springs and thereby degrade 

the quality of the resource.

Table 7. Summary of statistical tests for selected constituents

and physical property differences between base-flow and

stormflow samples.

[Tests are based on data from tables 3 and 5]

Constituent/physical

property p-value Type of test

Silica, total 0.001 t-test

Total dissolved solids 0.006 t-test

Strontium, total 0.001 rank sum

Sulfate, dissolved 0.024 rank sum

Barium, total 0.038 rank sum

Silica concentrations can be used to estimate contribution of cold-water recharge to the springs during base-flow 

and stormflow conditions. As previously discussed, silica is 

at saturated conditions along the hot-water flow path; because 

of this silica should behave as a relatively conservative species. This combined with the considerable difference in silica 

concentration for hot water and cold water makes silica an 

excellent tracer for mixing calculations. Estimated cold-water 

contributions to springs during stormflow were calculated 

using a binary mixing model and assumed values for coldand hot-water end-member silica concentrations. The mean 

silica concentration value for the cold-water springs and 

wells measured during this study and the study of Bedinger 

and others (1979) was about 8 mg/L. Silica concentrations of 

the deep flow-path hot waters are markedly different, exhibiting a maximum of about 47 mg/L. These values were used 

in the mixing model. Error inherent in the estimate calculations derives from these estimated cold-water and hot-water 

end-member silica concentrations; however, the values are 

relatively well constrained. An empirical understanding of 

the sensitivity of the calculation to error in the end-member 

values is illustrated by the fact that a 1 mg/L variance in the 

end-member results in an approximate change of 2 percent 

in the estimated cold-water contribution. Thus, the estimate 

is sensitive to this constituent, but, within the constraints of 

silica variation at individual springs, the result is still useful 

and informative—providing strong evidence of considerable contribution of shallow flow-path cold water to the hot 

springs. Estimated contribution of cold-water recharge to 

the hot springs during base-flow conditions varies from 0 to 

16 percent (table 8). Estimated contribution of cold-water 

recharge to the hot springs during stormflow conditions varies from 21 to 31 percent.

Figure 4. Relation between silica concentration and water 

temperature.

Influence of Locally Derived Recharge 

on the Water Quality and Temperature 

of Springs

Water-quality, water-temperature, isotopic, and radiochemical data can help assess the influence of locally derived 

recharge on water quality of the hot springs by providing 

information on the degree of mixing between deep flow-path, 

hot-water recharge and shallow flow-path, cold-water recharge 

in the discharge area. 

Water-Quality Data

Water-quality data show substantial differences in water 

chemistry of the springs during base-flow and stormflow 

conditions; that is, all the springs sampled indicated some 

measure of influence from local recharge. Of particular note 

are the results of statistical tests (t-test and rank sum test) that 

indicate statistically significant differences (p-values less than 

0.05) between the median values of base-flow and stormflow 

samples for several constituents and physical properties: 

silica, TDS, strontium, sulfate, and barium (table 7). While 

variations in these constituents and physical properties do 

not adversely affect water quality, the differences do provide 

evidence of variability in the factors controlling water quality 

of the hot springs and show that water quality is influenced 

by the locally derived, cold-water component of flow path 

WATER TEMPERATURE, IN DEGREES CELSIUS

0 10 20 30 40 50 60 70

SILICA CONCENTRATION, IN MILLIGRAMS PER LITER

0

10

20

30

40

50

Base flow

Stormflow
Table 8. Cold-water fraction estimates calculated from silica and total dissolved solids data for base-flow and stormflow 

conditions.

Spring Type of

spring

Silica-based coldwater fractionTotal dissolved solids based

 cold-water fraction

Base flow Stormflow Base flow Stormflow

Happy Hollow Cold 0.98 1.00 0.99 1.00

Spring 17 Hot 0.03 0.31 0.16 0.18

Spring 46 Hot 0.04 0.26 0.05 0.15

Spring 33 Hot 0.05 0.22 0.07 0.10

Spring 49 Hot 0.08 0.28 0.07 0.11

Spring 8 Hot 0.04 0.23 0.12 0.14

Spring 42 Hot 0.16 0.27 0.07 0.13

Spring 47 Hot 0.00 0.21 0.12 0.17

Spring 9 Hot 0.05 0.30 0.08 0.13

Spring 25 Hot 0.15 0.29 0.00 0.13

Total dissolved solids (TDS) is determined by weighing 

the residue left from a water sample upon evaporation and provides a quantitative measurement of all non-volatile dissolved 

species in solution. TDS is not a conservative measurement 

as it changes with any precipitation or dissolution reactions 

as rock-water interaction occurs; however, TDS is a robust 

measurement that changes considerably only upon precipitation or dissolution of solids or with mixing of different water 

sources with markedly differing TDS values. As such, when 

other geochemical factors influencing precipitation/dissolution 

reactions are expected to remain relatively constant, TDS can 

serve as a valuable indicator of mixing. A comparison of geochemical conditions during base-flow and stormflow sampling 

events shows no indication of varying effects on precipitation 

or dissolution, so the main controlling factor may be expected 

to be the varying input of cold-water recharge.

TDS concentrations also can be used to estimate contribution of cold-water recharge to the springs during base-flow and 

stormflow conditions. TDS concentrations for shallow flowpath waters in HSNP typically are about 20 mg/L as observed 

for cold water springs and wells. TDS concentrations for deep 

flow-path waters are different markedly, about 207 mg/L (the 

maximum hot spring TDS concentration measured). Assuming 

these as representative of the hot and cold TDS end members, and applying a simple, binary mixing model, estimated 

contribution of cold-water recharge to the hot springs during 

base-flow conditions varies from 0 percent (Spring 25) to 16 

percent (Spring 17) for individual springs (table 8). Estimated 

contribution of cold-water recharge to the hot springs during storm conditions varies from 10 (Spring 33) to 18 percent 

(Spring 17).

Water-Temperature Data

The continuous (3-minute interval) water-temperature 

data collected at Springs 8, 17, 25, and 46 are useful for showing relations between water temperature, local recharge, and 

storm events. Water temperature of springs varies seasonally, 

although water temperature also fluctuates rapidly in response 

to mixing of hot-springs water with locally derived recharge 

after storms. The decrease in water temperature resulting from 

specific storms has a non-linear relation with the amounts of 

precipitation associated with the storm events; response time 

for onset of water temperature decrease after a storm event is 

highly variable.

In addition to seasonal fluctuations, short-term fluctuations in water temperature occur (fig. 3) as a result of mixing of hot-springs water with locally derived recharge after a 

storm (note the downward “troughs” especially prominent for 

Spring 8, in figure 3). The relation between water temperature decreases and amount of precipitation associated with a 

specific storm event is non-linear. For example, storms with 

less than about 1.5 inches of precipitation resulted in temperature decreases of 0.5 °C or less at Spring 46 (fig. 5). Storms 

with greater than about 1.5 inches of precipitation resulted in 

highly variable decreases in water temperature at Spring 46: a 

storm with 1.8 inches of precipitation caused a 2.7 °C decrease 

in water temperature, but a storm with 2.4 inches of precipitation caused only a 0.26 °C decrease in water temperature. Data 

for Springs 8, 17, and 25 exhibited similar behavior. The variability of the water-temperature fluctuation is probably related 

to a combination of antecedent soil saturation conditions and 

the intensity, duration, and areal distribution of precipitation 

during the event.

12  Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Influence of Locally Derived Recharge on the Water Quality and Temperature of Springs 13

The response time for the water temperature at Springs 8, 

17, 25, and 46 to begin decreasing from the baseline temperature as a result of recharge from storms in 2000 and 2001 was 

highly variable. Storm-event, start-time data from automated 

rain gages indicated that water temperature at Spring 25 and 

Spring 46 began decreasing from their baseline temperature 

as quickly as 1 hour after the beginning of a storm event. The 

minimum response time for water temperature at Spring 8 was 

4 hours and at Spring 17 the minimum response time was 8 

hours.

The water temperature of the springs shows a relation 

to discharge. Figure 6 presents composited discharge and 

temperature data for the period of record at the spring reservoir. Water from springs 8, 9, 17, 25, 42, 46, 47, 49 and 25 

other springs flows into the spring reservoir (Yeatts, 2006). 

Figure 7 more closely illustrates the relation of temperature 

and discharge. Rapid increases or “spikes” in amount of 

discharge measured at the HSNP spring reservoir were related 

to decreases in temperature of the water flowing into the 

reservoir. This would indicate that thermal-water input to total 

spring discharge is relatively constant, but that increased coldwater input occurs during storm events. Bedinger and others 

(1979) offered an alternative hypothesis and stated that there 

should be an increase in hot-spring temperature with increasing spring discharge (apparently assuming increased discharge 

is from hot-water recharge). However, the more recent data 

indicate that, in terms of total discharge from the springs, the 

opposite relation is observed. Any time that the hot-water 

component of discharge to the springs increases, an increase 

in temperature may be expected because of the increased 

convection/conduction ratio (that is a greater mass of water 

carrying a proportionally greater heat load passes through an 

unchanging volume of rock with an unchanged conduction and 

heat capacity) and the resultant smaller proportional loss of 

thermal energy to the environment of the discharge area. Flow 

and temperature data collected at the spring reservoir indicate that temperature decreases as discharge increases. This 

relation is evidence that discharge increases are attributable to 

increases in the short-flow path, cold-water flow component. 

Data indicate that the hot-water component of discharge is 

PRECIPITATION, IN INCHES

0 1 2 3 4

MAXIMUM DECREASE IN TEMPERATURE, 

IN DEGREES CELSIUS 

0

1

2

3

Spring 46

Figure 5. Relation between water temperature decreases and 

precipitation at Spring 46.

1/1/91 1/1/92 1/1/93 1/1/94 1/1/95 1/1/96 1/1/97 1/1/98 1/1/99 1/1/00 1/1/01 1/1/02 1/1/03 1/1/04 1/1/05 59

60

61

62

63

64

300

400

500

600

700

800

Annual average temperature and discharge

Discharge

Period

not

monitored

Temperature DAILY TEMPERATURE, IN DEGREES CELSIUS

DAILY DISCHARGE, IN GALLONS PER DAY

(times 1,000)

Figure 6. Relation between discharge and water-temperature data at the Hot Springs National Park spring reservoir, showing the period 

of record—water years 1991 through 2005.
60.20

60.24

60.36

60.48

60.60

60.72

60.84

60.96

61.08

61.20

61.32

61.40

0.850

0.875

0.900

0.925

0.950

0.975

1.000

1.025

1.050

1.075

1.100

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

APRIL 1991

WATER TEMPERATURE, IN DEGREES CELSIUS DAILY MEAN DISCHARGE, IN CUBIC FEET PER SECOND

Water temperature

Discharge

Figure 7. Relation between discharge and water-temperature data at the Hot Springs National Park spring reservoir, April 1991.

14  Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Influence of Locally Derived Recharge on the Water Quality and Temperature of Springs 15

relatively stable; no changes in spring temperature that might 

be ascribed to changing hot water input have been observed.

Temperatures for shallow flow-path cold water are markedly different than long-flow-path hot water. Temperatures 

for shallow flow-path cold water (for example, Happy Hollow 

spring) typically are about 17 °C (near mean annual temperature). Temperatures for deep flow-path hot water (springs 8, 

17, 25, and 46) range from 54.2 °C to 63.7 °C, depending 

on the spring and whether the temperature was a base-flow 

or stormflow measurement. The effects of storms on water 

temperature appear to be greatest at Spring 8, although some 

effects are apparent in the other three hot springs instrumented 

for continuous temperature monitoring (fig. 3).

Estimated cold-water contribution to springs during stormflow 

were calculated using a binary mixing model and assumed 

values for cold- and hot-water temperatures. To ensure a 

conservative estimate of cold-water contribution from these 

calculations, the (likely erroneously conservative) assumption was made that there was zero cold-water input during 

the maximum temperature base-flow period observed during 

monitoring at the spring. Hence, the calculated estimates for 

cold-water contribution would actually be additive—applied 

to any cold-water input at base flow. Error inherent in the estimate calculation derives from these estimated temperatures— 

the cold-water temperature estimate is well constrained, and 

the hot-water estimate is reasonably well constrained but 

probably includes more error. An empirical understanding of 

the sensitivity of the calculation to error in the hot-water temperature is illustrated by the fact that a 2 degree variance in the 

temperature results in a 3 to 4 percent change in the estimated 

cold-water contribution. Thus, the estimate is sensitive to temperature, but, within the constraints of temperature variation at 

individual springs, the result is still useful and informative. For 

the continuously monitored springs, the maximum calculated 

estimate for cold-water inputs using these criteria were: 35 

percent for Spring 8, 30 percent for Spring 17, 5 percent for 

Spring 46, and 1 percent for Spring 25. It is interesting to 

note the temperature measurements taken in conjunction with 

stormflow sampling ranged from 0 to 7 percent and yielded 

a median result of 0.1 percent. This illustrates the variability 

from storm to storm and from spring to spring in cold-water 

input and suggests that while geochemical data derived from 

the sampling event for this study do provide evidence of coldwater influence, the particular time chosen for sampling was 

certainly not a time of maximum cold-water contribution for 

most of the springs. 

Water temperature and discharge at the spring reservoir were measured continually for most of the period from 

October 1990 through September 2001 (figs. 6 and 7). These 

data represent a composited value for temperature from all of 

the collected springs (springs 8, 9, 17, 25, 42, 46, 47, 49 and 

25 other springs); the temperature data are skewed to slightly 

lower temperature because of loss of thermal energy during 

transit from the spring discharge points through the collection 

system to the reservoir. The average temperature at the reservoir is about 61.2 °C; strong seasonal and diurnal variations 

are apparent. No cold-water springs are routed to the reservoir.

These composited reservoir data also indicate changes 

in discharge and temperature in response to storms. Analysis of these data can provide information about gross spring 

response to storms and about the total cold-water component 

of recharge to the springs associated with storms. Inspection 

of reservoir temperature data shows six or more storms each 

year during the period of record that result in a discernible 

decrease in temperature indicating a considerable cold-water 

recharge component to total thermal spring flow. Using the 

same mixing model approach for the reservoir as was used for 

individual springs temperature data (equation 1) an estimate 

of the quantity of cold water contributed can be derived. For 

example, a mid-April 1991 storm resulted in increased total 

flow from the springs and a decrease in composite spring 

temperature in the spring reservoir (fig. 7). A temperature 

decrease of about 0.8 °C was recorded; assuming an average 

cold-water temperature of 17 °C, this would indicate an estimated additional 2 percent cold-water contribution to the hot 

springs. Numerous such decreases in temperature are noted 

during the period of record, ranging up to a 25 percent coldwater contribution.

Isotopic and Radiochemical Data

Isotopic concentrations frequently can be used to determine sources of water for a spring because of the unique 

isotopic concentrations in the recharge sources. Most elements 

(including hydrogen, oxygen, carbon, sulfur, and strontium 

discussed below) occur naturally as mixtures of two or more 

isotopes. All the isotopes of an element exhibit the same 

chemical properties; however, different chemical, physical, 

or biological processes can influence the abundance of each 

isotope that is present in a particular sample (Hem, 1985). 

Stable isotopes are measured as the ratio of the two most 

abundant isotopes of a given element. For oxygen, the ratio is 

18O/16O. The relative abundance of the oxygen isotopes can be 

expressed as a deviation from a standard quantity using delta 

(d) notation and symbolized as d18O; values are expressed in 

per mil (‰):

d18Ox = (Rx - Rstd)/Rstd x 1000 (2)

where

d18Ox is the d value of a sample x,

Rx is the 18O/

16O ratio of that sample, and

Rstd is the 18O/

16O ratio of the standard.

A positive value of d18O represents water with more 18O 

relative to 16O than the standard water, Vienna Standard Mean 

Ocean Water (VSMOW) described by Gonfiantini (1978). A 

zero value of d18O represents water that has the same ratio of 18O to 16O as VSMOW. A negative value of d18O represents 

water with less 18O relative to 16O than VSMOW. Similar
notation is used to express the concentrations of the stable 

isotopes of hydrogen (deuterium/protium, dD) also referenced 

to VSMOW, carbon (13C/12C) referenced to the Pee Dee Belemnite (PDB), and sulfur isotopes (34S/32S) referenced to the 

Canyon Diablo Troilite (Hoefs, 1987).

Concentrations of d18O and dD do not indicate substantial 

differences in water chemistry of the springs during base-flow 

and stormflow conditions. Stormflow d18O and dD values are 

statistically indistinguishable from base-flow values; however, 

stormflow dD values exhibit a slightly lower mean (-30.0‰ 

compared to -29.0‰ for base flow) tending to plot below the 

base-flow values (fig. 8). Cold-water sample (dD) values also 

are low at -31.9‰ (Happy Hollow) and -28.1‰ (ArScenic). 

Oxygen and hydrogen isotopic data do not enable characterization of cold-water recharge to the hot springs. Hot-spring 

dD and d18O values are similar to local precipitation and 

shallow ground water; the data corroborate the conclusion of 

Bedinger and others (1979) that the hot springs are recharged 

locally with no evidence of meteoric water from outside the 

region being contributed to the hot springs.

about -27‰. C3 plants dominate in tropical, subtropical, and 

temperate forests. The C4 pathway is a geologically recent 

development that occurred as a plant response to dropping 

atmospheric CO2 concentrations in the early Tertiary. The C4 

pathway is a more efficient photosynthetic process and enables 

plants to thrive in hot and arid conditions. C4 plants have a 

mean d13C of about -12.5‰. C4 plant species represent only 

about 5 percent of terrestrial species; however, they dominate 

hot and arid ecosystems, including tropical, subtropical, and 

temperate grasslands. Degradation of vegetation in soils contributes soil gas CO2

 to soil pore space, and the light carbon 

isotopic composition of the parent organic matter is conveyed 

to the CO2 daughter product as soil carbon is oxidized. As 

ground water infiltrates, soil CO2 is brought into solution 

forming four main species of dissolved inorganic carbon: CO2

(aqueous), carbonic acid, bicarbonate, and carbonate. Bicarbonate is the predominant species at typical ground-water 

pH values (pH 6 through 10). These carbon species retain 

the carbon isotopic signature of the parent material. Ground 

water also dissolves mineral carbonate material to contribute 

to dissolved inorganic carbon. Mineral carbonate typically 

has a relatively heavy d13C value around 0‰ (Hoefs, 1987). 

Ground-water d13C values will reflect the input of these two 

sources, usually having an intermediate value indicative of the 

relative contribution of the carbon types. Assuming an original 

soil CO2 d13C value of -26‰ as Bedinger and others (1979) 

used (based on a mean C3 photosynthetic plant d13C value 

(Hoefs, 1987)) and a mineral carbonate value of 0‰, organic 

carbon contributed 52 to 55 percent of the total dissolved 

carbon present in base-flow and stormflow samples from the 

hot springs. Organic carbon contributed 87 percent of the total 

dissolved carbon present in Happy Hollow spring (cold water), 

which has water with very low bicarbonate content.

All stormflow samples from the hot springs were 

depleted in 34S, whereas, the cold spring sample was enriched. 

The d34S of the stormflow samples for the hot springs ranged 

from -5.65‰ at Spring 17 to -4.96‰ at Spring 25. The stormflow d34S for the cold-water Happy Hollow spring was 0.46‰. 

The differences in d34S may be attributable to two possible 

mechanisms: (1) differing sulfur sources for deep flow-path 

hot waters as compared with sources for the shallower flowpath cold waters. For example, weathering and dissolution of 

isotopically light sulfide minerals may be more prevalent for 

the hot-water flow path whereas dissolution of isotopically 

heavy sulfate minerals may be more prevalent for cold water, 

or (2) fractionation of dissolved sulfur species by sulfatereducing bacteria. Sulfate reduction typically results in preferential use of 32S for generation of sulfide species, resulting 

in enrichment of 34S residual dissolved sulfate (Krothe, 1983); 

this is the opposite of what is observed for hot-spring samples, 

all of which are in the negative d34S range, thereby making the 

first mechanism the more likely for hot springs water. 

Sulfur isotopic composition of the two cold-water spring 

samples are markedly different from the hot springs. d34S 

values for Happy Hollow spring and ArScenic spring were 

0.46‰ (stormflow) and 6.25‰ (base flow), respectively; these

-5.9 -5.8 -5.7 -5.6 -5.5 -5.4 -5.3 -5.2 -5.1

-33

-32

-31

-30

-29

-28

-27

Hot springs

 Base flow

 Stormflow

Cold springs

 Base flow

 Stormflow

δD, PER MIL

δ18O, PER MIL

Figure 8. Relation between deuterium/hydrogen and oxygen-18/

oxygen-16 isotopic ratios.

Concentrations of d13C do not indicate substantial differences in water chemistry of the springs during base-flow and 

stormflow conditions. Stormflow d13C values statistically are 

indistinguishable from base-flow values. Carbon isotope data 

indicate that a large component of dissolved inorganic carbon 

was ultimately derived from mineralization of organic carbon 

in recharge-zone soils. Fractionation that occurs during photosynthesis causes incorporation of isotopically light carbon in 

plant tissue with d13C values typically ranging from -10‰ to 

-30‰, depending on the vegetation type (Boutton and others, 1980; Deines, 1980). The degree of fractionation depends 

upon the photosynthetic pathway used by given groups of 

plants. The predominant photosynthetic pathways are the C3 

and C4 pathways, so called because of the length of certain 

carbon chains employed in photosynthesis. The C3 pathway 

is the most ancient and most common, operating in 85 percent 

of plant species. Most C3 plants have d13C values averaging 

16  Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Influence of Locally Derived Recharge on the Water Quality and Temperature of Springs 17

values are heavy relative to the thermal springs and are light 

relative to typical Ordovician to Mississippian-age rock sulfate 

d34S values (12‰ to 29‰) (Holser, 1977; Claypool and others, 

1980 ). This could indicate that dissolution of isotopically 

heavy sulfate and/or microbially mediated isotopic fractionation are more important for the cold-water flow paths.

At HSNP, strontium concentrations of the stormflow 

samples were slightly, but significantly higher (P = 0.001) 

than strontium of the base-flow samples (table 7; fig. 9). Plots 

of 87Sr/86Sr ratios and strontium concentration show that the 

stormflow samples for the hot springs plot primarily in the 

upper right area (high concentration-high ratio) of figure 9; 

base-flow samples are seen in the lower concentration area of 

the figure. Thus, strontium concentration data show a slight 

difference in base-flow and stormflow water chemistry for 

the springs. Interpretation of the cause of this phenomenon 

in view of cold-water recharge contribution is confounded 

by the existence of multiple strontium concentration populations in cold-water samples: (1) an end-member possibility 

with relatively high strontium concentrations and relatively 

low 87Sr/86Sr isotopic ratios, for example ArScenic spring 

with a concentration value of 135 mg/L and ratio of 0.7086 

(fig. 9); and the Whittington Park well with a concentration of 

260 μg/L and an unknown ratio (Bedinger and others, 1979), 

(2) an end-member possibility with relatively low strontium 

concentrations and 87Sr/86Sr ratios that are slightly higher 

than those seen in the hot springs, for example Happy Hollow 

Spring with a strontium concentration of 2.5 μg/L and 87Sr/86Sr 

ratio of 0.7129 (fig. 9) and the Sleepy Valley Spring with a 

strontium concentration of 10 μg/L and unknown isotopic 

value (Bedinger and others, 1979), and (3) an unsampled and 

therefore uncharacterized third end member possibility with 

relatively higher strontium concentrations and similar 87Sr/86Sr 

isotopic ratios. If mixing of the hot water component with one 

of these possible cold-water end-members is responsible for 

strontium chemistry in the hot springs, then for cold-water 

end-member possibility 1, which has high concentration-low 

ratio, an increase in concentration and decrease in ratio for 

the resultant mix would be expected. In the case of mixing 

with cold-water end-member possibility 2, which has low 

concentration-high ratio, a decrease in concentration and a 

slight increase in 87Sr/86Sr ratio would be expected. The third 

possible cold-water end member was not caught in the sampling regimen; this end member has a relatively high strontium 

concentration and a 87Sr/86Sr ratio that is comparable to that of 

the thermal waters. Applying a hyperbolic mixing model that 

incorporates terms for both concentration and isotopic composition (Faure and Mensing, 2005; Phillips and Koch, 2002) 

shows that end-member possibilities 1 and 2 are not feasible—

mixing with these with the thermal waters will result in end 

compositions not observed for the stormflow samples (fig. 9). 

For end-member possibility 1, consideration of concentration 

only (applying a binary mixing model and assuming thermal 

water strontium concentrations of 100 mg/L and cold-water 

concentrations of 200 mg/L—based on data from this study and 

from Bedinger (1979)—yields a range of possible mixtures 

with estimated cold-water contribution to hot spring discharge 

during storm events ranging from 8 to 17 percent; however, 

when the added dimension of isotope ratio is considered 

(applying a hyperbolic mixing model), the solution is shown 

as unfeasible (fig. 9); isotopic ratios measured are higher than 

would be predicted. For end-member possibility 2, neither 

concentration nor isotope ratio offers any feasible solution. 

The cold-water end-members possibilities 1 and 2 represented 

by Happy Hollow and ArScenic springs represent relatively 

old, deep flow-path cold waters. A possible cold-water contribution source not sampled during this study is the infiltration 

of precipitation and surface water through soils, regolith, and 

engineered and disturbed soils and other earth materials over 

and immediately surrounding the springs. The relatively rapid 

(but variable) temperature and geochemical response (seen in 

properties and constituents such as silica, TDS, and sulfate) of 

the hot springs to storm events indicates close connection with 

the surface and a short flow path. These data and the existence 

of this third end member may indicate that precipitation and 

stormflow water may be recharging within a few to several 

hundred feet of the spring discharge area, rapidly moving 

through the unsaturated zone to mix with deep flow-path hot 

waters, thereby impacting hot spring chemistry. Such a finding 

is of critical importance to the NPS because of the susceptibility of hot-spring water quality to activities occurring near the 

discharge area, including lawn, grounds, and facility maintenance; recreation and visitation; vehicle and machinery operation; occupation of and activities occurring within proximal 

buildings including the bath houses, the maintenance building, 

and the cooling facility. 

Isotopic tracer data provide evidence of the influence 

of cold-water recharge on the hot springs. Tritium and 35S 

indicate the input of a small component of shallow flow-path, 

cold-water recharge to the hot springs; however, the small 

amounts of 35S present are within the analytical precision and 

do not allow a statistical comparison between base-flow and 

stormflow results or mixing calculations.

The 87-day half life of 35S makes it an effective tracer 

for studying processes that occur on a timescale of 1 year or 

less (Michel, 2000). Standard atmospheric precipitation has an 

approximate 35S concentration of 10 mBq/L (or greater). The 

low median values of 35S (less than 0.1 mBq/L, eight of nine 

hot springs measured had 35S concentration below detection 

limits for base-flow samples) for the base-flow samples indicate recent recharge does not contribute substantially to base 

flow of the hot springs. Six out of eight stormflow samples 

exhibited detectable levels of 35S indicating that there is a 

small component of relatively young water in the hot springs; 

probably less than 1 year old. 35S concentrations in storm 

samples indicate that storm recharge is a component of hotspring discharge. 

These water-temperature, water-quality, isotopic and 

radiochemical data do indicate the important influence of 

shallow flow-path, cold-water recharge on the chemistry of the 

hot springs. Water-quality, water-temperature, isotopic, and 

radiochemical data provide multiple lines of evidence
90 95 100 105 110 115 120

0.71190

0.71192

0.71194

0.71196

0.71198

0.71200

0.71202

STRONTIUM CONCENTRATION, 

IN MICROGRAMS PER LITER

Hot Springs

 Base flow

 Stormflow

0 20 40 60 80 100 120 140 160

0.708

0.709

0.710

0.711

0.712

0.713

0.714

Hot- and cold-water springs

Hot-water springs only

STRONTIUM -87/STRONTIUM -86 ISOTOPIC RATIO

Cold-water

end-member

possibility 2

Cold-water

end-member

possibility 1

Cold-water

end-member

possibility 3

?

Range of 

modeled

values

Hot Springs

 Base flow

 Stormflow

Cold Springs

 Base flow

 Stormflow

Figure 9. Relation between strontium-87/strontium-86 and strontium.

18  Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
supporting the importance of the contribution of cold-water 

recharge to hot springs. Binary mixing models using silica and 

TDS give relatively consistent results and indicate that coldwater recharge from stormflow contributes an estimated 10 

to 31 percent of the flow of hot springs. Models using water 

temperature also give comparable results and indicate that 

cold-water recharge from stormflow contributes an estimated 

1 to 35 percent of the flow of hot springs. Although these data 

indicate that cold-water recharge from stormflow does contribute to the flow of the hot springs, data from additional stormflow events and also from additional hot springs are needed to 

refine the contribution of cold-water recharge.

Summary

The hot springs of HSNP consist of a mixture of water 

from two sources: a primary source about 4,400 years old (hot 

water) and a secondary source less than 20 years old (cold 

water). Hydrologic conditions in the zone of discharge—

including widespread distribution of fractures—enables integration of ground-water flow paths and mixing of the hot- and 

cold-water components of flow. Urbanization in the area near 

the hot springs has increased the potential for degradation of 

the quality of surface-water runoff and locally derived groundwater recharge to the springs. A previous study (Bedinger 

and others, 1979) indicated that a component of flow to some 

cold-water springs and wells in the vicinity of Hot Springs, 

Arkansas, showed evidence of contamination, such as elevated 

concentrations of nitrate and chloride, from localized recharge 

zones. Another work (C.S. Barks, U.S. Geological Survey, 

written commun., 1995) indicated that water from cold-water 

recharge areas might contribute 25 percent of the total flow to 

the hot springs during storms based on water temperature and 

flow data. This study verifies the existence and importance of 

the locally derived, cold-water component of water discharged 

by the hot springs. 

Water samples were collected from springs in the study 

area in September 2000 and October 2001. Water samples 

were collected at nine hot springs and two cold-water springs 

in September 2000 during base-flow conditions. Nine hot 

springs and one cold-water spring were resampled in October 

2001 after a storm event. Continuous temperature recorders 

were used to monitor the water temperature in four hot springs 

and one cold-water spring. The temperature monitors were 

activated in August 2000 and recorded water temperature continuously (at 3-minute intervals) through October 2002. Water 

samples were analyzed for a variety of dissolved chemical 

constituents (nutrients, major ions, trace elements, pesticides, 

semivolatile compounds, isotopes, and radiochemicals), physical properties, field measurements and bacteria. Knowledge of 

water chemistry can be used to interpret ground-water movement, source of the water, and temporal changes in chemical 

concentration. Comparison of sample analyses with the results 

from earlier studies dating back to the late 1800’s shows that 

little change in major, minor, and trace constituent chemistry 

has occurred for base-flow conditions and the water continues to have excellent quality. Minor differences are apparent 

(silica, zinc, and nutrient concentrations) that may be a result 

of sampling different springs, plumbing modifications (engineered collection and distribution infrastructure), different 

analytical techniques, and the natural geochemical differences 

characteristic of most ground-water systems. 

Water-temperature data (continuous and the temperatures 

collected at the time of water-quality sampling) do not indicate 

any long-term change in temperature through time. Similar 

to data presented in previous investigations, the water temperatures varied between springs and also varied at individual 

springs because of a variety of factors, including seasonal 

temperature, shallow-flow path recharge contribution, changes 

in the amount of spring discharge supplied to the spring reservoir, and construction on the network of supply pipes. 

The water temperature fluctuations in response to mixing 

of hot-spring water with locally derived recharge after a storm 

event varied with the amount of rainfall. For example, at 

Spring 46 storm events smaller than about 1.5 inches resulted 

in a temperature decrease of 0.5°C or less. However, storm 

events greater than about 1.5 inches resulted in highly variable 

decreases in water temperature: a 1.8-inch event caused a

2.7°C decrease in water temperature, but a 2.4-inch event 

caused only a 0.26°C decrease in water temperature. 

The response time for the water temperature to begin 

decreasing from the baseline temperature as a result of 

recharge from a storm event was highly variable. Storm-event, 

start-time data from automated rain gages indicated that water 

temperature at Spring 46 and Spring 25 began decreasing from 

the baseline temperature as quickly as 1 hour after the beginning of a storm. The minimum response time for water temperature at Spring 8 was 4 hours and at Spring 17 was 8 hours.

Water-quality, water-temperature, isotopic, and radiochemical data can help assess the influence of locally derived 

recharge on water quality of the hot springs by providing 

information on the degree of mixing between deep flow-path, 

hot-water recharge and shallow flow-path, cold-water recharge 

in the discharge area. 

Temperatures for shallow-flow-path waters in the area 

of HSNP typically are about 17°C (near mean annual temperature). Temperatures for deep flow-path waters range from 

54.2°C to 63.7°C, depending on the spring and whether the 

temperature was a base-flow or stormflow measurement. An 

estimate of the contribution of cold-water recharge above base 

flow during storms, using a binary mixing model, indicated 

the cold-water contribution during storms ranged from 1 to 35 

percent.

Water-quality data show distinguishable differences in 

chemistry of the springs during base-flow and stormflow conditions, that is, all the springs sampled indicated some measure 

of influence from local recharge. Silica, total dissolved solids, 

strontium, sulfate, and barium show statistically significant 

differences between the median values of base-flow and 

stormflow samples. While natural variations in these properSummary 19
ties do not degrade water quality, the differences do provide 

evidence of variability in the factors controlling water quality 

of the hot springs and show that water quality is influenced 

by the locally derived, cold-water component of flow to the 

springs. This younger, locally derived component of flow 

possibly is susceptible to surface influences associated with 

urbanization and changing land use that might introduce contaminants into the hot springs and thereby degrade the quality 

of the resource.

Water temperature and discharge at the spring reservoir 

have been measured continually for most of the time period 

from October 1990 through the present. These data provide 

information about gross spring response to storms and about 

the total cold-water component of recharge to the springs 

associated with storms. These data indicate changes in discharge and temperature in response to storms. Temperature 

data applied to a simple, binary mixing model indicate a 2 to 

25 percent cold-water recharge component input to total hotspring flow. 

Silica concentrations for shallow flow-path, cold-water 

recharge typically are about 8 mg/L (an average of local 

cold-water well and spring silica concentration values). Silica 

concentrations for deep-flow path waters are about 47 mg/L. 

Silica data applied to a binary mixing model indicate a 21 

to 31 percent contribution of cold-water recharge to the hot 

springs during stormflow conditions.

TDS concentrations for shallow flow-path waters typically are about 20 mg/L. TDS concentrations for deep-flowpath waters are about 207 mg/L (the maximum hot-spring 

silica concentration measured). TDS data applied to a binary 

mixing model indicate 10 to 18 percent contribution of coldwater recharge to the hot springs during stormflow conditions.

Low median values for 35S (less than 0.1 mBq/L) and low 

median tritium values (less than 5.7 pCi/L) were measured 

for the base-flow samples. These values indicate that recent 

recharge does not contribute significantly to base flow of the 

hot springs.

Water-quality, water-temperature, isotopic, and radiochemical data provide multiple lines of evidence supporting 

the importance of the contribution of shallow flow components 

to hot springs. Binary mixing models using silica and total dissolved solids indicate that cold-water recharge from stormflow 

contributes an estimated 10 to 31 percent of the flow of hot 

springs. Models using water temperature indicate that coldwater recharge from stormflow contributes an estimated 1 to 

35 percent of the flow of hot springs. Models using 87Sr/86Sr 

ratios indicate that cold-water recharge from stormflow 

contributes an estimated 8 to 17 percent of the flow of the hot 

springs. Although these data indicate that shallow recharge 

from stormflow does contribute to the flow of the hot springs, 

data from additional stormflow events and also from additional 

hot springs are needed to refine the contribution of cold-water 

recharge.

Selected References

Bedinger, M.S., Pearson, F.J., Jr., Reed, J.E., Sniegocki, R.T., 

and Stone, C.G., 1979, The waters of Hot Springs National 

Park, Arkansas-Their nature and origin: U.S. Geological 

Survey Professional Paper 1044-C, 33 p.

Boutton, T.W., Harrison, A.T., and Smith, B.B., 1980, Distribution of biomass of species differing in photosynthetic 

pathway along an altitudinal transect: Oecologia 45, p. 

287-298.

Branner, J.C., 1892, The mineral waters of Arkansas: Arkansas Geological Survey Annual Report for 1891, v. 1, 144 p.

Clark, I.D., and Fritz, P., 1997, Environmental isotopes in 

hydrogeology: Boca Raton, CRC Press, 328 p.

Claypool, G.E., Holser, W.T., Kaplan, I.R., Sakai, H., and Zak, 

I., 1980, The age curves of sulfur and oxygen isotopes in 

marine sulfate and their mutual interpretation: Chemical 

Geology, v. 28, p. 199-260.

Deines, P., 1980, The isotopic composition of reduced organic 

carbon in Fritz, P., and Fontes, J.C., eds., Handbook of 

Environmental Isotope Geochemistry: Amsterdam, Elsevier, 

1, p. 329-406.

Faure, Gunter, 1977, Principles of Isotope Geology: New 

York, New York, John Wiley and Sons, 464 p.

Faure, Gunter, and Mensing, Teresa, 2005, Isotopes—Principles and applications, 3rd ed: New York, New York: John 

Wiley and Sons, 897 p.

Fournier, R.O., and Rowe, J.J., 1966, Estimation of underground temperature from the silica content of water from 

hot springs and wetsteam wells: American Journal of Science, v. 264, p. 685-697.

Glascow, W, Jr., 1860, Hot Springs of Arkansas, with their 

Travertine Formation: St. Louis, Missouri, L. Gast Bro. and 

Co. 

Gonfiantini, R., 1978, Standards for stable isotope measurements in natural compounds: Nature, v. 271, p. 534-536.

Hamilton, J.B., and Blood, R.S., 1932, Report of construction 

of hot water collecting and distributing system, Hot Springs 

National Park, Hot Springs, Arkansas: National Park Service unpublished report.

20 Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Selected References 21

Hansen, A.H., and Gryskiewicz, D., 2003, Interactions 

between Heartland National Parks and surrounding land use 

change: Development of a conceptual models and indicators 

for monitoring accessed December 13, 2006 at URL http://

www.forestry.umt.edu/research/cesu/NEWCESU/Assets/

Individual%20Project%20Reports/NPS%20Projects/MSU/

2001Hansen%20HTLN%20final%20report%20%20Aug% 

202003.pdf.

Haywood, J.K., 1902, Report of analysis of the waters of the 

Hot Springs on the Hot Springs Reservation: U.S. 57th Congress, 1st session, Senate Document 282, 78 p.

Hem, J.D., 1985, Study and interpretation of the chemical 

characteristics of natural water (3rd ed.): U.S. Geological 

Survey Water-Supply Paper 2254, 263 p.

Hoefs, Jochen, 1987, Stable isotope geochemistry, 3rd ed., 

Berlin, Springer-Verlag, 241 p.

Holser, W.T., 1977, Catastrophic chemical events in the history of the ocean: Nature, v. 267, p. 403-408.

Kendall, C., and McDonnell, J.J., eds., 1998, Isotope tracers in 

catchment hydrology: Amsterdam, Elsevier, 839 p.

Koterba, M.T., Wilde, F.D., and Lapham, W.W., 1995, 

Ground-water data-collection protocols and procedures for 

the National Water-Quality Assessment Program: Collection 

and documentation of water-quality samples and related 

data: U.S. Geological Survey Open-File Report 95-399, 123 

p.

Krothe, N.C., and Libra, R.D., 1983, Sulfur isotopes and 

hydrochemical variations of spring waters in southern Indiana: Journal of Hydrology, v. 81, p. 267-283.

Kuroda, P.K., 1953, Radioactivity tables of some natural 

waters: Arkansas University Institute Science and Technology, 58 p.

Michel, R.L., Campbell, D.H., Clow, D., and Turk, J.T., 

2000, Timescales for migration of atmospherically-derived 

sulphate through an alpine/subalpine watershed: Water 

Resources Research, v. 36, p. 27-36.

National Park Service, 1997, Resources Management Plan: 

Hot Springs National Park: National Park Service, 48 p.

National Park Service, 1998, Baseline water quality data 

inventory and analysis: Hot Springs National Park: National 

Park Service, Water Resources Division, Technical Report 

NPS/NRWRD/NRTR-98/150, 426 p.

Owen, D.D., 1860, Second report of a geological reconnaissance of the middle southern counties of Arkansas: Philadelphia, Pa., C. Sherman and Sons, p. 18-27.

Phillips, Donald, and Koch, Paul, 2002, Incorporating concentration dependence in stable isotope mixing models: 

Oecologia, v. 130, p. 114-125.

Rantz, S.E., and others, 1982, Measurement and computation 

of streamflow: Volume 1. Measurement of stage and discharge: U.S. Geological Survey Water Supply Paper 2175, 

284 p.

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http://www.epa.gov/safewater/mcl.html.

Wagner, R.J., Mattraw, H.C., Ritz, G.F., and Smith, B. A., 

2000, Guidelines and standard procedures for continuous 

water-quality monitors: Site selection, field operation, calibration, record computation, and reporting: U.S. Geological 

Survey Water-Resources Investigations Report 00-4252, 14 

p.

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Yeatts, D.S., 2006, Characteristics of thermal springs and the 

shallow ground-water system at Hot Springs National Park, 

Arkansas: U.S. Geological Survey Scientific Investigations 

Report 2006-5001, 35 p.
Table 3. Nutrients, major ion, trace element, isotope, radiochemical, physical property, field measurement, and bacteria

[Base-flow sample collected September 2000; Stormflow sample collected October 2001; mg/L, milligrams per liter; mg/L, micrograms

mBeq/L, milli-Becquerels per liter; μS/cm at 25 deg. C, microsiemens per centimeter at 25 degrees Celsius; <, less than; E, estimated;

Hot springs

Base flow Stormflow

Constituent name

Maximum

contaminant

level

Method

reporting

level

Minimum Median Maximum Minimum Median Maximum

Nutrients (mg/L) 

Nitrogen ammonia, as 

nitrogen, total -- 0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10

Nitrogen nitrate, as nitrogen, dissolved -- 0.5 <0.5 <0.5 <.0.5 -- -- --

Nitrite plus nitrate, as 

nitrogen, total 10 0.10 <0.10 <0.10 0.10 <0.10 <0.10 <0.10

Phosphorus ortho, as 

phosphorus, dissolved -- 0.5 <0.5 <0.5 <0.5 -- -- --

Phosphorus, total -- 0.05 <.05 0.29 0.51 E.028 E.042 0.11

Major ions (mg/L) 

Calcium, total -- 0.2 38.9 42.6 47.9 38.0 41.2 41.9

Magnesium, total -- 0.20 4.22 4.70 4.97 4.20 4.30 4.37

Potassium, total -- 3 <3 <3 <3 <3 <3 <3

Sodium, total recoverable -- 5 <5 <5 <5 <5 <5 <5

Chloride, dissolved -- 3.0 <3.0 <3.0 <3.0 <3.0 <3.0 <3.0

Fluoride, dissolved 4 1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0

Silica, total -- 0.5 40.8 44.9 46.9 35.1 36.3 38.7

Sulfate, dissolved -- 5.0 7.0 7.3 7.5 6.8 7.0 7.3

Trace elements (μg/L) 

Aluminum, total -- 100 <100 <100 <100 <100 <100 106

Antimony, total 6 10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

Arsenic, total 10 10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

Barium, total 2,000 10.0 75.5 133 141 87.7 146 156

Beryllium, total 40 5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0

Boron, total -- 100 <100 <100 <100 <100 <100 <100

Cadmium, total 5 5.0 <5.0 <5.0 0.5 <5.0 <5.0 <5.0

Chromium, total 100 10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

Cobalt, total -- 10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

Copper, total -- 10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

22  Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Tables 23

data for samples collected at hot- and cold-water springs in 2000 and 2001.

per liter; pCi/L, picocuries per liter; VSMOW, Vienna standard mean ocean water;

--, data unavailable; n/a, not applicable]

Spring 42 Spring 46 Spring 33 Spring 25

Base flow Stormflow Base flow Stormflow Base flow Stormflow Base flow Stormflow

 

<0.1 E0.056 E0.053 E0.042 <0.1 E0.060 E0.032 E0.041

<0.5 -- E.17 -- <0.5 -- <0.5 --

E0.064 <0.10 <0.1 E0.053 E0.036 E0.090 E0.054 <0.10

<0.5 -- <0.5 -- <0.5 -- <0.5 --

0.49 E0.041 0.065 E0.048 0.46 0.087 0.51 E0.036

 

39.3 41.2 43.5 41.7 42.6 41.6 38.9 41.9

4.29 4.32 4.69 4.34 4.72 4.36 4.22 4.37

E1.31 E1.13 E1.39 E1.13 E1.44 E1.13 E1.24 E1.22

E3.3 E2.6 E4.1 E2.8 E3.9 E2.3 E2.9 E2.5

E2.3 E2.8 E2.4 E2.7 E2.4 E2.7 E2.3 E2.7

E0.18 E0.22 E0.19 E0.22 E0.19 E0.22 E0.19 E0.22

40.8 36.3 45.6 36.8 44.9 38.3 41 35.8

7.1 7.3 7.3 7.1 7.5 7.2 7.4 7.0

 

<100 <100 <100 106 <100 E95.0 <100 <100

<10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

<10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

136 147 136 142 141 156 129 152

<5.0 <5.0 E1.2 <5.0 E1.4 <5.0 <5.0 <5.0

E11.4 E19.2 E10.4 E19.5 E9.6 E17.4 E14.1 E16.7

<5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0

<10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

<10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

<10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0
Table 3. Nutrient, major ion, trace element, isotope, radiochemical, physical property, field measurement, and bacteria

[Base-flow sample collected September 2000; Stormflow sample collected October 2001; mg/L, milligrams per liter; mg/L, micrograms

mBeq/L, milli-Becquerels per liter; mS/cm at 25 deg. C, microsiemens per centimeter at 25 degrees Celsius; <, less than; E, estimated;

Hot springs

Base flow Stormflow

Constituent name

Maximum

contaminant

level

Method

reporting

level

Minimum Median Maximum Minimum Median Maximum

Iron, total -- 100 <100 <100 <100 <100 <100 208

Lead, total -- 3.0 <3.0 <3.0 <3.0 <3.0 <3.0 3.5

Manganese, total -- 10.0 E1.6 215 231 <10.0 234 261

Mercury, total rec. 2 0.2 <0.2 <0.2 <0.2 <0.20 <0.20 0.22

Molybdenum, total -- 20.0 <20.0 <20.0 <20.0 <20.0 <20.0 <20.0

Nickel, total -- 40.0 <40.0 <40.0 <40.0 <40.0 <40.0 <40.0

Selenium, total 5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0

Silver, total 50 10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

Strontium, total -- 10.0 93.8 102 110 108 114 117

Thallium, total 2 10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

Tin, total -- 100 <100 <100 <100 <100 <100 <100

Vanadium, total -- 10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

Zinc, total -- 20.0 <20.0 <20.0 20.4 <20.0 <20.0 <20.0

Isotopes and radiochemicals 

Carbon d13C ratio per million -- n/a -14.09 -13.83 -13.55 -14.19 -13.93 -13.49

Carbon-14, counting error, water, filtered, 

percent -- n/a 0.34 -- 0.34 -- -- --

Carbon-14, water, filtered, percent -- n/a 37.72 -- 37.72 -- -- --

Radium 226 dissolved, planchet count (pCi/L) -- 0.1 <0.1 2.44 3.17 -0.0203 2.47 2.96

24  Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Tables 25

data for samples collected at hot- and cold-water springs in 2000 and 2001.—Continued

 per liter; pCi/L, picocuries per liter; VSMOW, Vienna standard mean ocean water;

--, data unavailable; n/a, not applicable]

Spring 42 Spring 46 Spring 33 Spring 25

Base flow Stormflow Base flow Stormflow Base flow Stormflow Base flow Stormflow

E36.9 E19.3 E24.5 E44.3 E60.3 E36.9 E20.0 E39.1

<3.0 <3.0 <3.0 <3.0 <3.0 3.5 <3.0 <3.0

231 239 196 198 230 261 215 246

<0.2 E0.047 <0.2 <0.20 <0.2 <0.20 <0.2 <0.20

<20.0 <20.0 <20.0 <20.0 <20.0 <20.0 <20.0 <20.0

<40.0 <40.0 <40.0 <40.0 <40.0 <40.0 <40.0 <40.0

<5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0

<10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

104 114 110 117 110 114 99.4 117

<10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

<100.0 <100 <100.0 <100 <100.0 <100 <100.0 <100

<10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

20.4 E4.4 <20.0 <20.0 E10.0 E13.3 <20.0 <20.0

 

-14.0 -14.16 -13.65 -13.83 -13.89 -13.88 -14.08 -14.19

-- -- 0.34 -- -- -- -- --

--

 -- 37.72 -- -- -- -- --

2.44 2.47 2.26 2.04 3.05 2.64 3.17 2.96
Table 3. Nutrient, major ion, trace element, isotope, radiochemical, physical property, field measurement, and bacteria

[Base-flow sample collected September 2000; Stormflow sample collected October 2001; mg/L, milligrams per liter; mg/L, micrograms

mBeq/L, milli-Becquerels per liter; mS/cm at 25 deg. C, microsiemens per centimeter at 25 degrees Celsius; <, less than; E, estimated;

Hot springs

Base flow Stormflow

Constituent name

Maximum

contaminant

level

Method

reporting

level

Minimum Median Maximum Minimum Median Maximum

Radium 228, dissolved 

(pCi/L) -- 1.0 <1.0 <1.0 1.4 0.329 0.538 1.08

Radium-226, dissolved 

(pCi/L)

5 

 

(combinedwith

Radium228)

 n/a 0.0348 0.571 0.713 0.029 0.578 0.677

Radium-228, dissolved 

(pCi/L) n/a 0.335 0.419 0.568 0.332 0.428 0.501

Tritium, total (pCi/L) -- 5.7 <5.7 <5.7 9.6 <5.7 1.6 3.5

Tritium, total, 2 sigma 

PE (pCi/L) -- n/a 3.8 3.8 4.5 1.9 2.6 2.6

Tritium units -- 1.78 1.19 1.19 1.41 0.59 0.81 0.81

Uranium-234, 2 sigma 

precision estimate 

(pCi/L)

-- 0.00123 0.0171 0.0273 0.00484 0.00908 0.0111

Uranium-234, dissolved. 

(pCi/L) -- 0.1 <0.1 <0.1 <0.1 0.00262 0.0105 0.0184

Uranium-235, 2 sigma 

precision estimate 

(pCi/L)

-- n/a 0.00237 0.00873 0.0273 0.00122 0.00367 0.00812

Uranium-235, dissolved 

(pCi/L) -- 0.1 <0.1 <0.1 <0.1 -0.00061 0.000319 0.0045

Uranium-238, 2 sigma 

precision estimate 

(pCi/L)

-- n/a 0.00892 0.0159 0.0273 0.00507 0.00661 0.00825

Uranium-238, dissolved 

(pCi/L) -- 0.1 <0.1 <0.1 <0.1 0.00262 0.00472 0.00766

Deuterium, VSMOW, ‰ -- n/a -30.05 -29.04 -28.26 -30.95 -30.035 -27.61

Oxygen 18, VSMOW, ‰ -- n/a -5.56 -5.5 -5.16 -5.57 -5.51 -5.46

Strontium 87/86 -- n/a 0.71193 0.71195 0.71197 0.71192 0.71197 0.71200

Sulfur 35 (mBeq/L) -- 0.1 <0.1 <0.1 7 -0.4 0.1 1.8

Sulfur d34S, parts per 

thousand -- n/a -5.65 -5.28 -4.97 -5.7 -5.15 -4.96

26  Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Tables 27

data for samples collected at hot- and cold-water springs in 2000 and 2001.—Continued

 per liter; pCi/L, picocuries per liter; VSMOW, Vienna standard mean ocean water;

--, data unavailable; n/a, not applicable]

Spring 42 Spring 46 Spring 33 Spring 25

Base flow Stormflow Base flow Stormflow Base flow Stormflow Base flow Stormflow

1.19 0.476 <1.0 0.706 <1.0 0.538 <1.0 0.395

0.571 0.576 0.539 0.495 0.693 0.608 0.713 0.677

0.497 0.437 0.449 0.467 0.419 0.428 0.414 0.397

<5.7 -1 <5.7 0.6 6.7 3.5 <5.7 0

3.8 2.6 3.8 1.9 4.5 2.6 3.8 2.6

1.19 0.81 1.19 0.59 1.41 0.81 1.19 0.81

0.0171 0.00484 0.0273 0.00908 0.0203 0.00978 0.0235 0.00825

<0.1 0.0034 <0.1 0.0097 <0.1 0.0155 <0.1 0.00766

0.00237 0.00341 0.0273 0.00122 0.00655 0.00344 0.0125 0.00367

<0.1 0.0017 <0.1 -0.00061 <0.1 -0.00028 <0.1 0.000319

0.0124 0.0069 0.0273 0.00544 0.0177 0.00507 0.0197 0.00825

<0.1 0.00679 <0.1 0.00394 <0.1 0.00367 <0.1 0.00766

-29.19 -27.61 -28.26 -30.04 -29.04 -30.95 -30.05 -29.11

-5.49 -5.51 -5.41 -5.48 -5.16 -5.48 -5.5 -5.54

0.71193 0.71195 0.71196 0.71197 0.71193 0.71196 0.71194 0.71196

<1 0.9 <1 -0.1 <1 0.8 <1 1.8

-5.5 -5.19 -- -5.14 -- -5.7 -4.97 -4.96
Table 3. Nutrient, major ion, trace element, isotope, radiochemical, physical property, field measurement, and bacteria

[Base-flow sample collected September 2000; Stormflow sample collected October 2001; mg/L, milligrams per liter; mg/L, micrograms

mBeq/L, milli-Becquerels per liter; μS/cm at 25 deg. C, microsiemens per centimeter at 25 degrees Celsius; <, less than; E, estimated;

Hot springs

Base flow Stormflow

Constituent name

Maximum

contaminant

level

Method

reporting

level

Minimum Median Maximum Minimum Median Maximum

Physical properties, 

field parameters, and 

bacteria

 

Total dissolved solids 

(residue on evaporation 

at 180 degrees Celsius)

-- 10 177 194 207 174 182 188

pH, field (standard units)

-- 0.1 6.5 7.4 7.8 6.9 7.6 7.6

Specific conductance

(μS/cm at 25 deg. C)

-- 2.6 267 287 296 238 293 293

Water temperature 

(degrees Celsius)

-- 0 54.2 62.7 63.7 54.2 63.6 63.6

Alkalinity, dissolved

(mg/L as HCO3)

-- 2 118 125 128 122 136 136

Acid neutralizing Capacity, field (mg/L as 

CaCO3)

-- 2 113 123 130 9 129 129

Alkalinity, dissolved

(mg/L as HCO3)

-- 2 144 152 156 149 160 166

E. coli (colonies/100 mL)

-- 1 <1 <1 K120 <1 <1 25

Coliform, fecal 0.7 (colonies/100 mL)

-- 1 <1 <1 K200 <1 <1 <1

28  Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Tables 29

data for samples collected at hot- and cold-water springs in 2000 and 2001.—Continued

 per liter; pCi/L, picocuries per liter; VSMOW, Vienna standard mean ocean water;

--, data unavailable; n/a, not applicable]

Spring 42 Spring 46 Spring 33 Spring 25

Base flow Stormflow Base flow Stormflow Base flow Stormflow Base flow Stormflow

194 182 198 179 194 188 207 183

6.8 6.9 7.4 7.1 6.8 6.9 6.7 7.4

275 273 287 254 291 256 278 258

61.9 62.1 55.7 55.8 58.2 58.6 63.7 63.6

128 133 127 131 124 131 125 136

113 126 123 124 115 128 114 10

156 162 155 160 151 160 152 166

<1 <1 <1 <1 <1 25 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1
Table 3. Nutrient, major ion, trace element, isotope, radiochemical, physical property, field measurement, and bacteria 

[Base-flow sample collected September 2000; Stormflow sample collected October 2001; mg/L, milligrams per liter; mg/L, micrograms

mBeq/L, milli-Becquerels per liter; mS/cm at 25 deg. C, microsiemens per centimeter at 25 degrees Celsius; <, less than; E, estimated;

Spring 49 Spring 9 Spring 8

Constituent name Base flow Stormflow Base flow Stormflow Base flow Stormflow

Nutrients (mg/L)

Nitrogen ammonia, total 0.029 <0.10 E0.046 E0.039 -- E0.033

Nitrogen nitrate, dissolved E.17 -- E0.18 -- E0.17 --

Nitrite plus nitrate, as nitrogen, 

total <0.1 E0.071 <0.1 <0.10 -- E0.031

Phosphorus ortho, dissolved <0.5 -- <0.5 -- <0.5 --

Phosphorus, total E0.022 E0.042 <0.05 E0.040 -- 0.11

Major ions (mg/L) 

Calcium, total 41.4 39.8 43.2 41.1 47.2 41

Magnesium, total 4.54 4.23 4.7 4.3 4.9 4.24

Potassium, total E1.42 E1.17 E1.16 E1.01 E1.36 E.913

Sodium, total recoverable E3.95 E2.70 E3.66 E2.83 E4.55 E2.07

Chloride, dissolved E2.4 E2.7 E2.3 E2.7 E2.3 E2.7

Fluoride, dissolved E.19 E.22 E.18 E.22 E.19 E.22

Silica, total 44.0 36.2 44.9 35.2 45.6 38.2

Sulfate, dissolved 7.1 6.9 7.0 6.9 7.1 6.9

Trace elements (μg/L) 

Aluminum, total <10.0 <100 <100 E95.8 <100 <100

Antimony, total <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

30 Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Tables 31

 data for samples collected at hot- and cold-water springs in 2000 and 2001.—Continued

per liter; pCi/L, picocuries per liter; VSMOW, Vienna standard mean ocean water;

--, data unavailable; n/a, not applicable]

Spring 17 Spring 47 Happy Hollow ArScenic Precipitation site

Base flow Stormflow Base flow Stormflow Base flow Stormflow Base flow Stormflow Base flow Stormflow

<0.1 E0.038 -- E0.042 0.13 <0.10 <0.1 -- -- --

E0.2 -- E0.17 -- E0.18 -- <0.5 -- -- --

0.1 E0.050 -- E0.043 <0.1 <0.10 <0.1 -- -- --

<0.5 -- <0.5 -- <0.5 -- <0.5 -- -- --

0.29 0.072 -- E0.028 0.087 0.065 E0.027 -- -- --

 

40.7 38 47.9 41.6 E.172 0.469 38.6 -- -- --

4.71 4.20 4.97 4.30 0.263 0.262 1.51 -- -- --

E1.41 E0.914 E1.16 E1.28 <0.3 <3.00 E0.611 -- -- --

E4.04 <5.00 E3.87 E2.78 E1.52 <5.00 E1.48 -- -- --

E2.3 E2.7 E2.4 E2.7 E2.6 3.5 E2.8 -- -- --

E0.19 E0.22 E0.19 E0.22 E0.11 E0.18 E0.19 -- -- --

45.8 35.1 46.9 38.7 8.92 8.17 11.7 -- -- --

7.4 7.1 7.3 6.8 E1.4 E1.8 5.6 -- -- <1.2

 

<100 E98.5 <100 106 E34.9 E91.5 <100 -- -- --

<10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0 -- -- --
Table 3. Nutrient, major ion, trace element, isotope, radiochemical, physical property, field measurement, and

[Base-flow sample collected September 2000; Stormflow sample collected October 2001; mg/L, milligrams per liter; mg/L, micrograms

mBeq/L, milli-Becquerels per liter; mS/cm at 25 deg. C, microsiemens per centimeter at 25 degrees Celsius; <, less than; E, estimated:

Spring 49 Spring 9 Spring 8

Constituent name Base flow Stormflow Base flow Stormflow Base flow Stormflow

Arsenic, total <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

Barium, total 101 94.2 75.5 136 136 146

Beryllium, total E1.6 <5.0 E1.5 <5.0 <5.0 <5.0

Boron, total E131 E17.3 E11.7 E17.1 E11.1 E15.9

Cadmium, total <5.0 <5.0 <5.0 <5.0 <5.0 <5.0

Chromium, total <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

Cobalt, total <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

Copper, total <10.0 <10.0 <10.0 <10.0 E4.9 <10.0

Iron, total <100 208 E18.4 E21.1 E13.1 E6.2

Lead, total 

<3.0

 

<3.0

 

<3.0

 

<3.0

 

<3.0

 

<3.0

Manganese, total 

110

 

85.5

 

E1.6

 

203

 

229

 

234

Mercury, total rec. 

<0.20

 

0.22

 

<0.20

 

<0.20

 

<0.20

 

<0.20

Molybdenum, total 

<20.0

 

<20.0

 

<20.0

 

<20.0

 

<20.0

 

<20.0

Nickel, total 

<40.0

 

<40.0

 

<40.0

 

<40.0

 

<40.0

 

<40.0

Selenium, total 

<5.0

 

<5.0

 

<5.0

 

<5.0

 

<5.0

 

<5.0

Silver, total 

<10.0

 

<10.0

 

<10.0

 

<10.0

 

<10.0

 

<10.0

Strontium, total 

102

 

113

 

109

 

115

 

94.9

 

113

Thallium, total 

<10.0

 

<10.0

 

<10.0

 

<10.0

 

<10.0

 

<10.0

Tin, total 

<100

 

<100

 

<100

 

<100

 

<100

 

<100

32  Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Tables 33

bacteria data for samples collected at hot- and cold-water springs in 2000 and 2001.—Continued

per liter; pCi/L, picocuries per liter; VSMOW, Vienna standard mean ocean water;

--, data unavailable; n/a, not applicable]

Spring 17 Spring 47 Happy Hollow ArScenic Precipitation site

Base flow Stormflow Base flow Stormflow Base flow Stormflow Base flow Stormflow Base flow Stormflow

<10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0 -- -- --

82.5 87.7 133 147 E7.2 18.7 E8.1 -- -- --

E1.6 <5.0 <5.0 <5.0 E1.1 <5.0 <5.0 -- -- --

E11.2 E16.1 E8.1 E16.7 <100 E12.4 <100 -- -- --

<5.0 <5.0 0.5 <5.0 <5.0 <5.0 <5.0 -- -- --

<10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0 -- -- --

<10.0 <10.0 <10.0 <10.0 <10.0 E.42 <10.0 -- -- --

<10.0 <10.0 E6.1 <10.0 11.1 <10.0 19.8 -- -- --

E17.0 <100 E15.8 E6.8 E72.7 E56.5 119 -- -- --

<3.0 <3.0 <3.0 <3.0 4.6 <3.0 <3.0 -- -- --

<10.0 <10.0 227 236 10.4 E6.6 41.5 -- -- --

<0.20 <0.20 <0.20 <0.20 <0.20 <.20 <0.2 -- -- --

<20.0 <20.0 <20.0 <20.0 <20.0 <20.0 <20.0 -- -- --

<40.0 <40.0 <40.0 <40.0 <40.0 <40.0 <40.0 -- -- --

<5.0 <5.0 <5.0 <5.0 <5.0 <5.0 <5.0 -- -- --

<10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0 -- -- --

102 108 93.8 115 E2.5 E5.2 135 -- -- --

<10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0 -- -- --

<100 <100 <100 <100 <100 <100 <100 -- -- --
Table 3. Nutrient, major ion, trace element, isotope, radiochemical, physical property, field measurement, and

[Base-flow sample collected September 2000; Stormflow sample collected October 2001; mg/L, milligrams per liter; mg/L, micrograms

mBeq/L, milli-Becquerels per liter; mS/cm at 25 deg. C, microsiemens per centimeter at 25 degrees Celsius; <, less than; E, estimated:

Spring 49 Spring 9 Spring 8

Constituent name Base flow Stormflow Base flow Stormflow Base flow Stormflow

Vanadium, total <10.0 <10.0 <10.0 <10.0 <10.0 <10.0

Zinc, total <20.0 <20.0 <20.0 <20.0 <20.0 <20.0

Isotopes and radiochemicals 

Carbon 13/12 ratio per million -14.08 -14.1 -13.83 -13.93 -13.55 -13.75

Carbon-14, counting error, 

water, filtered, percent -- -- -- -- -- --

Carbon-14, water, filtered, 

percent -- -- -- -- -- --

Radium 226 dissolved, planchet count (pCi/L) 1.82 0.153 0.196 2.45 2.76 2.48

Radium 228, dissolved 

(pCi/L) <1.0 0.49 <1.0 0.885 1.31 0.953

Radium-226, dissolved 

(pCi/L) 0.445 0.0859 0.103 0.581 0.644 0.578

Radium-228, dissolved 

(pCi/L) 0.403

 

0.332 0.393 0.501 0.519 0.411

Tritium, total (pCi/L) 9.6 1.9 <5.7 1.9 <5.7 1.6

Tritium, total, 2 sigma PE 

(pCi/L) 3.8 2.6 3.8 2.6 3.8 2.6

Tritium units 1.19 0.81 1.19 0.81 1.19 0.81

Uranium-234 2 sigma PE 

(pCi/L) 0.0159 0.00819 0.0182 0.0089 0.00123 0.00983

Uranium-234,DIS. (pCi/L) <0.1 0.0105 <0.1 0.0129 <0.1 0.0135

Uranium-235, 2 sigma PE 

(pCi/L) 0.0134 0.0046 0.00892 0.00451 0.00615 0.00385

34  Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Tables 35

bacteria data for samples collected at hot- and cold-water springs in 2000 and 2001.—Continued

per liter; pCi/L, picocuries per liter; VSMOW, Vienna standard mean ocean water;

--, data unavailable; n/a, not applicable]

Spring 17 Spring 47 Happy Hollow ArScenic Precipitation site

Base flow Stormflow Base flow Stormflow Base flow Stormflow Base flow Stormflow Base flow Stormflow

<10.0 <10.0 <10.0 <10.0 <10.0 <10.0 <10.0 -- -- --

<20.0 <20.0 <20.0 <20.0 E4.7 <20.0 E11.0 -- -- --

 

-13.76 -13.97 -13.58 -13.49 -22.72 -22.93 -14.22 -- -- --

-- -- -- -- -- -- 0.43 -- -- --

-- -- -- -- -- -- 47.83 -- -- --

<0.10 -0.0203 3.02 2.64 0.718 0.859 0.816 -- -- --

<1.0 0.329 1.4 1.08 <1.0 0.508 <1.0 -- -- --

0.0348 0.029 0.684 0.613 0.223 0.254 0.246 -- -- --

0.335

 

0.377 0.568 0.464 0.461 0.424 0.435 --

-- --

<5.7 0.6 <5.7 1.9 <5.7 6.1 7.7 -- -- --

3.8 2.6 3.8 2.6 3.8 2.6 3.8 -- -- --

1.19 0.81 1.19 0.81 1.19 0.81 1.19 -- -- --

0.0145 0.00953 0.0142 0.0111 0.0377 0.0328 0.146 -- -- --

<0.10 0.00262 <0.10 0.0184 <0.10 0.106 0.612 -- -- --

0.00873 0.00812 0.00799 0.00321 0.00861 0.00889 0.0132 -- -- --
Table 3. Nutrient, major ion, trace element, isotope, radiochemical, physical property, field measurement, and

[Base-flow sample collected September 2000; Stormflow sample collected October 2001; mg/L, milligrams per liter; mg/L, micrograms

mBeq/L, milli-Becquerels per liter; mS/cm at 25 deg. C, microsiemens per centimeter at 25 degrees Celsius; <, less than; E, estimated:

Spring 49 Spring 9 Spring 8

Constituent name Base flow Stormflow Base flow Stormflow Base flow Stormflow

Uranium-235, dissolved 

(pCi/L) <0.1 0.00181 <0.1 0.00114 <0.1 0.0

Uranium-238 2 sigma PE 

(pCi/L) 0.0159 0.00695 0.00892 0.00661 0.0107 0.00552

Uranium-238, dissolved 

(pCi/L) <0.1 0.00692 <0.1 0.00658 <0.1 0.00472

Deuterium, VSMOW, ‰ -28.38 -29.23 -28.63 -30.03 -28.82 -30.23

Oxygen 18, VSMOW, ‰ -5.56 -5.47 -5.52 -5.56 -5.56 -5.57

Strontium 87/86 0.71197 0.71198 0.71195 0.71200 0.71196 0.71198

Sulfur 35 (mBeq/L) <1 0.1 <1 -0.4 <1 -0.1

Sulfur 34/32 (‰) -5.42 -5.03 -5.11 -5.15 -5.28 -5.16

Physical properties, field 

parameters, and bacteria 

Total dissolved solids 194 186 192 182 184 181

pH, field (standard units) 7.5 6.9 7.6 7.1 7.8 7.6

Specific conductance

(uS/cm at 25 deg. C) 285 263 296 293 290 252

Water temperature (degrees 

Celsius 63.5 60.4 63.7 62.8 63 61.9

Alkalinity, dissolved

(mg/L) 124 131 126 131 125 128

Acid neutralizing capacity, 

field (mg/L as CaCO3) 125 121 127 129 129 10

Alkalinity, dissolved (mg/L 

as HCO3) 151 160 154 160 152 156

E. coli, mtec mf,w (col./100 

mL) <1 <1 <1 <1 K120 <1

Coliform fecal 0.7 (col./100 

mL) <1 <1 <1 <1 K200 <1

36  Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Tables 37

bacteria data for samples collected at hot- and cold-water springs in 2000 and 2001.—Continued

per liter; pCi/L, picocuries per liter; VSMOW, Vienna standard mean ocean water; 

--, data unavailable; n/a, not applicable]

Spring 17 Spring 47 Happy Hollow ArScenic Precipitation site

Base flow Stormflow Base flow Stormflow Base flow Stormflow Base flow Stormflow Base flow Stormflow

<0.100 0.0045 <0.10 0.000279 <0.10 0.0107 <0.10 -- -- --

0.0247 0.00717 0.014 0.00595 0.0153 0.0143 0.0189 -- -- --

<0.10 0.00262 <0.10 0.00391 <0.10 0.0263 <0.10 -- -- --

-29.25 -30.12 -29.5 -29.01 -31.85 -32.71 -28.11 -- -- -66.04

-5.46 -5.46 -5.51 -5.56 -5.77 -5.65 -5.46 -- -- -9.66

0.71193 0.71192 0.71196 0.71197 0.71292 0.71202 0.70860 -- -- --

<1 0.1 7 0.2 2.1 0.3 <1 -- -- --

-5.65 -5.23 -5.14 -5.1 -- 0.46 6.25 -- -- 1.2

 

177 174 185 176 22 20 119 -- -- --

6.5 7.4 7.6 7.3 4.7 5.1 6.9 -- -- --

267 238 296 256 22 23 250 -- -- --

54.2 54.2 62.7 62.8 18 17.6 19.4 -- -- --

118 122 125 132 E1.3 E1.2 92.1 -- -- --

115 9 130 10 3 0.4 93 -- -- --

144 149 152 161 E1.6 E1.5 112 -- -- --

<1 <1 <1 <1 <1 <1 K12 -- -- --

<1 <1 <1 <1 <1 <1 K74 -- -- --
Table 4. Pesticide and semivolatile concentrations for samples collected at hot- and cold-water springs in 2000 and 2001.—Continued

[Base-flow sample collected September 2000; Stormflow sample collected October 2001; All concentrations for samples collected are in micrograms per liter;

 <, less than; --, data unavailable]

Constituent name

Spring 49 Spring 9 Happy Hollow ArScenic

Maximum

contaminant

level1

Base

 flow

StormflowBase 

flow

StormflowBase 

flow

StormflowBase

flow

Stormflow

1,2,5,6-dibenzanthracene total -- <10 <10 <10 <10 -- <10 <10 --

2,4,5-trichlorophenol, whole

water, total

-- <10 <10 <10 <10 -- <10 <10 --

2,4,6-trichlorophenol, total -- <10 <10 <10 <10 -- <10 <10 --

2,4,dimethylphenol, total -- <10 <10 <10 <10 -- <10 <10 --

2,4-dichlorophenol, total -- <10 <10 <10 <10 -- <10 <10 --

2,4-dinitrophenol, total -- <50 <50 <50 <50 -- <50 <50 --

2,4-dinitrotoluene, total -- <10 <10 <10 <10 -- <10 <10 --

2,6-dinitrotoluene, total -- <10 <10 <10 <10 -- <10 <10 --

2-chloronaphthalene, total -- <10 <10 <10 <10 -- <10 <10 --

2-chlorophenol, total -- <10 <10 <10 <10 -- <10 <10 --

2-nitroaniline, whole water,

recoverable

-- <50 <50 <50 <50 -- <50 <50 --

2-nitrophenol, total -- <10 <10 <10 <10 -- <10 <10 --

3,3’-dichlorobenzidine, total -- <50 <50 <50 <50 -- <50 <50 --

3-nitroaniline, water, whole, 

total

-- <50 <50 <50 <50 -- <50 <50 --

4,6-dinitroorthocresol, total -- <50 <50 <50 <50 -- <50 <50 --

4-bromophenyl phenyl ether,

water, unfiltered, recoverable

-- <10 <10 <10 <10 -- <10 <10 --

4-chloroaniline, water, filtered,

recoverable

-- <10 <10 <10 <10 -- <10 <10 --

4-chlorophenyl phenyl ether,

water, unfiltered, recoverable

-- <10 <10 <10 <10 -- <10 <10 --

4-nitroaniline, water, whole,

recoverable

-- <50 <50 <50 <50 -- <50 <50 --

4-nitrophenol, total -- <50 <50 <50 <50 -- <50 <50 --

Acenaphthene, total -- <10 <10 <10 <10 -- <10 <10 --

Acenaphthylene, total -- <10 <10 <10 <10 -- <10 <10 --

Aldrin, total (water) -- <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --

Alpha BHC, total -- <0.05 <0.050 <0.05 <0.050 -- <0.050

<0.005

--

Anthracene, total -- <10 <10 <10 <10 -- <10 <10 --

38  Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Tables 39

Table 4. Pesticide and semivolatile concentrations for samples collected at hot- and cold-water springs in 2000 and 2001.—Continued

[Base-flow sample collected September 2000; Stormflow sample collected October 2001; All concentrations for samples collected are in micrograms per liter;

 <, less than; --, data unavailable]

Constituent name

Spring 49 Spring 9 Happy Hollow ArScenic

Maximum

contaminant

level1

Base

 flow

StormflowBase 

flow

StormflowBase 

flow

StormflowBase

flow

Stormflow

Benzene, nitro-, water, unfiltered, recoverable-- <10 <10 <10 <10 -- <10 <10 --

Benzo (a) pyrene, total -- <10 <10 <10 <10 -- <10 <10 --

Benzo (b) fluoranthene, total -- <10 <10 <10 <10 -- <10 <10 --

Benzo (k) fluoranthene, total -- <10 <10 <10 <10 -- <10 <10 --

Benzo(a)anthracene, water,

unfiltered,recoverable

-- <10 <10 <10 <10 -- <10 <10 --

Benzo[ghi]perylene, water,

unfiltered, recoverable

-- <10 <10 <10 <10 -- <10 <10 --

Beta benzene hexachloride,

total 

-- <0.05 <0.050 <0.05 <0.050 -- <0.050

<0.05

--

Bis(2-chloroethoxy) methane,

total 

-- <10 <10 <10 <10 -- <10 <10 --

Bis(2-chloroethyl) ether, water, unfiltered, recoverable-- <10 <10 <10 <10 -- <10 <10 --

Bis(2-chloroisopropyl) ether,

total 

-- <10 <10 <10 <10 -- <10 <10 --

Bis(2-ethylhexyl)phthalate,

whole, water

-- <10 <10 <10 <10 -- <10 <10 --

Carbazole, water, unfiltered, 

recoverable

-- <10 <10 <10 <10 -- <10 <10 --

Chlordane, cis isomer,

water, whole, total

-- <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --

Chlordane, trans isomer,

water, whole, total 

-- <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --

Chrysene, total -- <10 <10 <10 <10 -- <10 <10 --

Cyclopentadiene, hexachloro-,

water, unfiltered, recoverable

-- <50 <50 <50 <50 -- <50 <50 --

Delta benzene hexachloride,

total 

-- <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --

Dibenzofuran, water, whole,

total

-- <10 <10 <10 <10 -- <10 <10 --

Dieldrin, total -- <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --

Diethyl phtlate, total -- <10 <10 <10 <10 -- <10 <10 --

Dimethyl phthalate, total -- <10 <10 <10 <10 -- <10 <10 --

Di-n-butylphthalate, total -- <10 <10 <10 <10 -- <10 <10 --

Dinoctyl phthalate, total -- <10 <10 <10 <10 -- <10 <10 --

Endosulfan I, water, whole,

recoverable

-- <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --
Table 4. Pesticide and semivolatile concentrations for samples collected at hot- and cold-water springs in 2000 and 2001.—Continued

[Base-flow sample collected September 2000; Stormflow sample collected October 2001; All concentrations for samples collected are in micrograms per liter;

 <, less than; --, data unavailable]

Constituent name

Spring 49 Spring 9 Happy Hollow ArScenic

Maximum

contaminant

level1

Base

 flow

StormflowBase 

flow

StormflowBase 

flow

StormflowBase

flow

Stormflow

Endosulfan II, water, unfiltered, recoverable-- <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --

Endosulfan sulfate, total -- <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --

Endrin aldehyde, total -- <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --

Endrin, ketone, water,

whole, total 

-- <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --

Endrin, water, unfiltered,

recoverable

2 <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --

Fluoranthene, total -- <10 <10 <10 <10 -- <10 <10 --

Fluorene, total -- <10 <10 <10 <10 -- <10 <10 --

Heptachlor epoxide, total 0.2 <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --

Heptachlor, total 0.4 <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --

Hexachlorobenzene, total 1 <10 <10 <10 <10 -- <10 <10 --

Indeno (1,2,3-cd) pyrene,

total 

-- <10 <10 <10 <10 -- <10 <10 --

Isophorone, total -- <10 <10 <10 <10 -- <10 <10 --

Lindane, total 0.2 <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --

Methoxychlor, total 4.0 <0.10 <0.10 <0.10 <0.10 -- <0.10 <0.10 --

N-butylbenzyl phthalate,

total 

-- <10 <10 <10 <10 -- <10 <10 --

N-nitrosodi-n-propylamine,

total 

-- <10 <10 <10 <10 -- <10 <10 --

N-nitrosodiphenylamine,

total 

-- <10 <10 <10 <10 -- <10 <10 --

P,P’ DDD, total -- <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --

P,P’ DDE total -- <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --

P,P’ DDT, total -- <0.05 <0.050 <0.05 <0.050 -- <0.050 <0.05 --

Parachlorometa cresol, total -- <10 <10 <10 <10 -- <10 <10 --

Pentachlorophenol, total 1 <50 <50 <50 <50 -- <50 <50 --

Phenanthrene, total -- <10 <10 <10 <10 -- <10 <10 --

Phenol, water, unfiltered -- <10 <10 <10 <10 -- <10 <10 --

Pyrene, total -- <10 <10 <10 <10 -- <10 <10 --

Toxaphene, total 3 <5 <5 <5 <5 -- <5 <5 --

Benzene, 1,2,4-trichloro-, 

water, unfiltered, recoverable

-- <10 <10 <10 <10 -- <10 <10 --

40 Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Tables 41

Table 4. Pesticide and semivolatile concentrations for samples collected at hot- and cold-water springs in 2000 and 2001.—Continued

[Base-flow sample collected September 2000; Stormflow sample collected October 2001; All concentrations for samples collected are in micrograms per liter;

 <, less than; --, data unavailable]

Constituent name

Spring 49 Spring 9 Happy Hollow ArScenic

Maximum

contaminant

level1

Base

 flow

StormflowBase 

flow

StormflowBase 

flow

StormflowBase

flow

Stormflow

Benzene, 1,3-dichloro-, water,

unfiltered, recoverable

-- <10 <10 <10 <10 -- <10 <10 --

Benzene, 1,4-dichloro-, water,

unfiltered, recoverable

-- <10 <10 <10 <10 -- <10 <10 --

Benzene, o-dichloro-, water,

unfiltered, recoverable

-- <10 <10 <10 <10 -- <10 <10 --

Ethane, hexachloro-, water,

unfiltered, recoverable

-- <10 <10 <10 <10 -- <10 <10 --

Hexachlorobutadiene, total -- <10 <10 <10 <10 -- <10 <10 --

Naphthalene, total -- <10 <10 <10 <10 -- <10 <10 --

1

U.S. Environmental Protection Agency, 2003.
Table 5. Nutrient, major ion, trace element, isotope, radiochemical, physical property, and field-measurement data for samples 

collected at hot- and cold-water springs in water years, 1972, 2000, and 2001.—Continued

[BF, base-flow sample collected September 2000; SF, stormflow sample collected October 2001; BR, Bedinger and others, 1979; 

<, less than; E, estimated; --, data unavailable; mg/L, milligrams per liters; μg/L, micrograms per liter; pCi/L, picocuries per liter; 

VSMOW, Vienna Standard Mean Ocean Water; μS/cm at 25 deg. C, microsiemens per centimeter at 25 degrees Celsius]

Constituent name

Spring 42 Spring 46 Spring 33

BF SF BR BF SF BR BF SF BR

Nutrients, mg/L

Nitrogen nitrate, dissolved <0.5 -- 0.0 E.17 -- 0.0 <0.5 -- 0.0

Phosphorus ortho, dissolved <0.5 -- 0.04 <0.5 -- 0.04 <0.5 -- 0.02

Major ions, mg/L

Calcium, total 39.3 41.2 45 43.5 41.7 45 42.6 41.6 45

Magnesium, total 4.29 4.32 4.8 4.69 4.34 4.8 4.72 4.36 4.8

Potassium, total E1.31 E1.13 1.5 E1.39 E1.13 1.5 E1.44 E1.13 1.5

Sodium, total rec. E3.32 E2.56 4.0 E4.13 E2.82 4.0 E3.93 E2.33 4.0

Chloride, dissolved E2.3 E2.8 1.9 E2.4 E2.7 1.9 E2.4 E2.7 1.9

Fluoride, total E.18 E.22 0.2 E.19 E.22 0.2 E.19 E.22 0.2

Silica, total 40.8 36.3 42 45.6 36.8 42 44.9 38.3 42

Sulfate, dissolved 7.1 7.3 8.6 7.3 7.1 7.8 7.5 7.2 8.2

Trace elements, μg/L

Aluminum, total <100 <100 0.0 <100 106 0.0 <100 E95.0 0.0

Iron, total E36.9 E19.3 10 E24.5 E44.3 330 E60.3 E36.9 40

Manganese, total 231 239 230 196 198 250 230 261 270

Strontium, total 104 114 110 110 117 110 110 114 110

Zinc, total 20.4 E4.4 0.02 <20.0 <20.0 0.07 E10.0 E13.3 0.08

Isotopes and radiochemicals

δ13C, ‰ -14.09 -- -- -13.65 -14.8 -13.89 -- -14.6

Carbon-14, counting error, 

water, filtered, percent

-- -- -- 0.34 -- -- -- -- --

Carbon-14, water, filtered, 

percent

-- -- -- 37.72 -- -- -- -- --

Tritium, total (pCi/L) <5.7 <5.7 2.7 5.7 0.6 3.1 6.7 3.5 0.9

Tritium, total, 2 sigma precision estimate (pCi/L)3.8 2.6 0.3 3.8 1.9 0.6 4.5 2.6 0.6

δD, VSMOW, ‰ -29.19 -27.61 -28 -28.26 -30.04 -29 -29.04 -30.95 -28

δ18O, VSMOW, ‰ -5.49 -5.51 -5.4 -5.41 -5.48 -5.5 -5.16 -5.48 -5.4

Physical properties and field 

measurements

Total dissolved solids (residue on evaporation at 180 

degrees Celsius

194 182 188 198 179 187 194 188 188

pH, field (standard units) 6.80 6.90 6.93 7.41 7.1 7.01 6.80 6.89 7.13

Specific conductance (μS/cm at 

25 deg. C)

275 273 272 287 254 269 291 256 269

Water temperature (deg. C.) 61.9 62.1 61.3 55.7 55.8 58.3 58.2 58.6 57.6

42  Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Table 5. Nutrient, major ion, trace element, isotope, radiochemical, physical property, and field-measurement data for samples 

collected at hot- and cold-water springs in water years, 1972, 2000, and 2001.—Continued

[BF, base-flow sample collected September 2000; SF, stormflow sample collected October 2001; BR, Bedinger and others, 1979; 

<, less than; E, estimated; --, data unavailable; mg/L, milligrams per liters; μg/L, micrograms per liter; pCi/L, picocuries per liter; 

VSMOW, Vienna Standard Mean Ocean Water; μS/cm at 25 deg. C, microsiemens per centimeter at 25 degrees Celsius]

Constituent name

Spring 42 Spring 46 Spring 33

BF SF BR BF SF BR BF SF BR

Alkalinity, dissolved (mg/L as 

CaCO3)

128 133 159 127 131 164 124 131 164

Alkalinity, dissolved (mg/L as 

HCO3)

156 162 194 155 160 200 151 160 200

Summary 43
Table 5. Nutrient, major ion, trace element, isotope, radiochemical, physical property, and field-measurement data for samples collected at hot- and cold-water springs in water years, 1972, 2000, and 2001.—Continued

[BF, base-flow sample collected September 2000; SF, stormflow sample collected October 2001; BR, Bedinger and others, 1979; <, less than; 

E, estimated; --, data unavailable; mg/L, milligrams per liters; μg/L, micrograms per liter; pCi/L, picocuries per liter; VSMOW, Vienna Standard Mean Ocean Water; μS/cm at 25 deg. C, microsiemens per centimeter at 25 degrees Celsius]

Constituent name Spring 49 Spring 17 Happy Hollow

BF SF BR BF SF BR BF SF BR

Nutrients, mg/L

Nitrogen nitrate, dissolved E.17 -- 0.00 E.2 -- 0.00 E.18 -- 0.00

Phosphorus ortho, dissolved <0.5 -- 0.06 <0.5 -- 0.00 <0.5 -- 0.03

Major ions, mg/L

Calcium, total 41.4 39.8 44 40.7 38 44 E.172 0.469 0.2

Magnesium, total 4.54 4.23 4.8 4.71 4.2 4.6 0.263 0.262 0.3

Potassium, total E1.42 E1.17 1.5 E1.41 E.914 1.5 <0.3 <3.00 0.2

Sodium, total rec. E3.95 E2.70 3.8 E4.04 <5.00 3.9 E1.52 <5.00 1.3

Chloride, dissolved E2.4 E2.7 1.9 E2.3 E2.7 1.8 E2.6 3.5 2.3

Fluoride, total E0.19 E0.22 0.2 E0.19 E0.22 0.2 E0.11 E0.18 0.1

Silica, total 44 36.2 41 45.8 35.1 41 8.92 8.17 8.4

Sulfate, dissolved 7.1 6.9 8.2 7.4 7.1 7.8 E1.4 E1.8 1.4

Trace elements, μg/L

Aluminum, total <100 <100 0.0 <100 E98.5 0.0 E34.9 E91.5 0.00

Iron, total <100 208 60 E17.0 <100 0.00 E72.7 E56.5 0.00

Manganese, total 110 85.5 250 <10.0 <10.0 0.00 10.4 E6.6 0.00

Strontium, total 102 113 110 102 108 110 E2.5 E5.2 0.00

Zinc, total <20.0 <20.0 0.06 <20.0 <20.0 0.05 E4.7 <20.0 0.03

Isotopes and radiochemicals

δ13C, ‰ -14.08 -- -16.1 -13.76 -- -14.1 -22.72 -- --

Carbon-14, counting error, 

water, filtered, percent

-- -- -- -- -- -- -- -- --

Carbon-14, water, filtered, 

percent

-- -- -- -- -- -- -- -- --

Tritium, total (pCi/L) 9.6 1.9 9 <5.7 0.6 3.0 <5.7 6.1 1.1

Tritium, total, 2 sigma precision estimate (pCi/L)3.8 2.6 0.4 3.8 2.6 0.5 3.8 2.6 0.6

δD, VSMOW, ‰ -28.38 -29.23 -28 -29.25 -30.12 -30 -31.85 -32.71 -30

δ18O, VSMOW, ‰ -5.56 -5.47 -5.6 -5.46 -5.46 -5.4 -5.77 -5.65 -5.8

Physical properties and field 

measurements

Total dissolved solids (residue 

on evaporation at 180 

degrees Celsius

194 186 184 177 174 184 22 20 1.4

pH, field (standard units) 7.49 6.87 6.95 6.5 7.42 7.7 4.66 5.07 4.58

Specific conductance (μS/cm 

at 25 deg. C)

285 263 268 267 238 266 22 23 22

Water temperature (deg. C.) 63.5 60.4 61.8 54.2 54.2 55.4 18 17.6 17.5

44  Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Table 5. Nutrient, major ion, trace element, isotope, radiochemical, physical property, and field-measurement data for samples collected at hot- and cold-water springs in water years, 1972, 2000, and 2001.—Continued

[BF, base-flow sample collected September 2000; SF, stormflow sample collected October 2001; BR, Bedinger and others, 1979; <, less than; 

E, estimated; --, data unavailable; mg/L, milligrams per liters; μg/L, micrograms per liter; pCi/L, picocuries per liter; VSMOW, Vienna Standard Mean Ocean Water; μS/cm at 25 deg. C, microsiemens per centimeter at 25 degrees Celsius]

Constituent name Spring 49 Spring 17 Happy Hollow

BF SF BR BF SF BR BF SF BR

Alkalinity, dissolved (mg/L as 

CaCO3)

124 131 155 118 122 160 E1.3 E1.2 1.0

Alkalinity, dissolved (mg/L as 

HCO3)

151 160 189 144 149 195 E1.6 E1.5 1.2

Summary 45
For more information concerning the research described 

 in this report, contact:

U.S. Geological Survey

Arkansas Water Science Center

401 Hardin Road

Little Rock, AR 72211-3528

(501) 228-3600

http://ar.water.usgs.gov

46  Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas
Bell and Hays—Water Quality and Temperature of Springs in Hot Springs National Park, Arkansas—Scientific Investigations Report 2007–5004

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