Water-Level Variations and Their Effects 

on Tree Growth and Mortality and on 

the Biogeochemical System at the 

Phytoremediation Demonstration 

Site in Fort Worth, Texas, 1996–2003

By Christopher L. Braun, Sandra M. Eberts, Sonya A. Jones, and 

Gregory J. Harvey

U.S. Department of the Interior

U.S. Geological Survey

In cooperation with the U.S. Air Force, Aeronautical Systems Center,

Environmental Management Directorate, Wright-Patterson Air Force Base, Ohio

Scientific Investigations Report 2004–5107
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2004

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS

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Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report.

Suggested citation:

Braun, C.L., Eberts, S.M., Jones, S.A., and Harvey, G.J., 2004, Water-level variations and their effects on tree growth

and mortality and on the biogeochemical system at the phytoremediation demonstration site in Fort Worth, Texas,

1996–2003: U.S. Geological Survey Scientific Investigations Report 2004–5107, 39 p.
iii

Contents

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

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

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

Description of the Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

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

Water-Level Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Factors Affecting Water-Level Variations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Aquifer Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Precipitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Drawdown Induced by the Trees—Transpiration Effects . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Irrigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Effects of Water-Level Variations on Tree Growth and Mortality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Effects of Water-Level Variations on Ground-Water Biogeochemistry . . . . . . . . . . . . . . . . . . . . . . . . 13

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

References Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Appendix 

Figures—Maps showing (a) lines of equal ground-water depths and (b) water-level 

altitude contours for 

A–1. Aug. 17–22, 1996 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

A–2. Oct. 28, 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

A–3. Feb. 11, 1998 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

A–4. June 22, 1998 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

A–5. Oct. 10, 2000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

A–6. Jan. 8, 2001 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

A–7. July 12–13, 2001 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

A–8. Jan. 15–16, 2002 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

A–9. July 18–19, 2002 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

A–10. Jan. 14–15, 2003 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Tables

A–1. Well-construction data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

A–2. Trichloroethene concentrations from six sampling events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

A–3. cis-Dichloroethene concentrations from six sampling events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

A–4. Molar ratios of trichloroethene to cis-dichloroethene from six sampling events . . . . . . . . . . . . . 37

A–5. Dissolved oxygen concentrations from six sampling events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

A–6. Dissolved organic carbon concentrations from September 2000 sampling event . . . . . . . . . . . 39

A–7. Quality-control results for trichloroethene (TCE), cis-dichloroethene (cis-DCE), and 

molar ratios of TCE to cis-DCE (TCE/cis-DCE) for four of six sampling events . . . . . . . . . . . . . . . . 39
iv

Figures

1–5. Maps showing: 

1. Location of study area, alluvial aquifer ground-water-flow directions, and 

trichloroethene (TCE) plume of October 2002 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2. Land-surface altitudes in study area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3. Location of wells within the study area and location of low hydraulic conductivity 

zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4. Location and relative diameter of existing trees, January 2003, and relations between 

mean tree diameter and ground-water depth (September 2000) and between mortality 

and ground-water depth (September 2000) within the whip plantation . . . . . . . . . . . . . . . . . . . . . . . 7

 5. Location and relative diameter of existing trees and location of trees stunted by 

beaver activity within the caliper plantation, January 2003 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

6. Graphs showing daily mean water-level altitudes for wells 513, 514, and 515, daily mean 

stream stage at Farmers Branch Creek, and monthly precipitation at Naval Air Station-Joint 

Reserve Base Carswell Field, November 1998–August 2002 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

7–11. Maps showing:

7. Estimated drawdown attributed to planted trees, June 22, 1998 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

8. Estimated drawdown attributed to planted trees, September 19–20, 2000 . . . . . . . . . . . . . . . . . . . 12

9. Lines of equal ground-water depths and (a) molar ratio of trichloroethene (TCE) to 

cis-dichloroethene (cis-DCE), and (b) dissolved oxygen concentrations, June 22, 1998 . . . . . . 14

10. Lines of equal ground-water depths and (a) molar ratio of trichloroethene (TCE) to 

cis-dichloroethene (cis-DCE), and (b) dissolved oxygen concentrations, January 8, 

2001 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

11. Lines of equal ground-water depths and (a) molar ratio of trichloroethene (TCE) to 

cis-dichloroethene (cis-DCE), and (b) dissolved oxygen concentrations, July 12–13, 

2001 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

12. Boxplots showing distribution of (a) dissolved oxygen concentrations, September 2000–

July 2002, and (b) molar ratios of trichloroethene (TCE) to cis-dichloroethene (cis-DCE), 

September 2000–July 2002 for selected ground-water depths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

13. Map showing location and relative diameter of remaining trees within the whip 

plantation near well 516, graphs of dissolved oxygen concentration and molar ratio of 

trichloroethene (TCE) to cis-dichloroethene (cis-DCE) from well 516 samples for selected 

sampling events, and graph of monthly precipitation from the nearby Naval Air Station-Joint 

Reserve Base Carswell Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Vertical Datum

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88). 
Water-Level Variations and Their Effects 

on Tree Growth and Mortality and on 

the Biogeochemical System at the 

Phytoremediation Demonstration 

Site in Fort Worth, Texas, 1996–2003

By Christopher L. Braun1, Sandra M. Eberts1, Sonya A. Jones1, and Gregory J. Harvey2

Abstract

In 1996, a field-scale phytoremediation demonstration 

project was initiated and managed by the U.S. Air Force at a site 

in western Fort Worth, Texas, using a plantation of 1-year-old 

stems harvested from branches of eastern cottonwoods during 

the dormant season (whips) and a plantation of 1-year-old 

eastern cottonwood seedlings (calipers). The primary objective 

of the demonstration project was to determine the effectiveness 

of eastern cottonwoods at reducing the mass of dissolved 

trichloroethene transported within an alluvial aquifer. The U.S. 

Geological Survey conducted a study, in cooperation with the 

U.S. Air Force, to determine water-level variations and their 

effects on tree growth and mortality and on the biogeochemical 

system at the phytoremediation site. As part of the study, waterlevel and water-quality data were collected throughout the duration of the project.

This report presents water-level variations at periodic 

sampling events; data from August 1996 to January 2003 are 

presented in this report. Water levels are affected by aquifer 

properties, precipitation, drawdown attributable to the trees in 

the study area, and irrigation. This report also evaluates the 

effects of ground-water depth on tree growth and mortality 

rates and on the biogeochemical system including subsurface 

oxidation-reduction processes.

Overall, both whips and calipers showed a substantial 

increase in height, canopy diameter, and trunk diameter over the 

first 3 years of the study. By the fifth growing season (September 2000), the height of the calipers varied predictably with 

height decreasing with increasing depth to ground water. Percent mortality was relatively constant at about 25 percent in the 

whip plantation in January 2003 where ground-water levels 

were less than 10 feet below land surface during the drought in 

September 2000. The mortality rate increased where the 

ground-water levels were greater than 10 feet below land surface and approached 90 percent where ground-water levels 

were between 12 and 13 feet.

A decrease in molar ratio of trichloroethene to cisdichloroethene was measured in ground water within and 

downgradient from the planted area over time. Decreases in 

these ratios appeared to be related to ground-water depth. The 

molar ratios of trichloroethene to cis-dichloroethene during the 

third growing season were relatively constant, between 3.0 and 

4.0, in samples collected from wells across the site. By the 

end of the fifth growing season the lowest ratio was measured 

in areas where ground-water depth was less than 10 feet below 

land surface; these same areas had the lowest dissolved oxygen 

concentrations (0.93 to 1.7 milligrams per liter) and the highest 

dissolved organic carbon concentrations (1.6 to 1.8 milligrams 

per liter). This indicates that between the third and fifth growing 

seasons, a labile fraction of dissolved organic carbon had been 

introduced into the aquifer by the planted trees that was capable 

of stimulating reductive dechlorination of trichloroethene. 

Introduction

A field-scale phytoremediation demonstration project 

was initiated in 1996 by the U.S. Air Force at a site in western 

Fort Worth, Tex., near Air Force Plant 4 (AFP4) (fig. 1). The 

primary objective of the project was to determine the effectiveness of eastern cottonwoods (Populus deltoides) at reducing 

the mass of dissolved trichloroethene (TCE) that is being transported within an alluvial aquifer. TCE has been used at the 

site in aircraft manufacturing processes for decades; spills and 

leaks from TCE tanks within the manufacturing building have 

resulted in shallow ground-water contamination on-site and 

downgradient from the facility (Eberts and others, 2003). 

Before the development of the phytoremediation demonstration 

site, which is located 0.9 mile downgradient from the suspected 

source, natural attenuation of TCE at the site was limited to 

sorption, dispersion, dilution, and possibly volatilization. Some 

1 U.S. Geological Survey. 

2 Environmental Management Directorate, Wright-Patterson Air Force 

Base, Ohio. 
2 Water-Level Variations and Their Effects on Tree Growth and Mortality and on the Biogeochemical System, 1996–2003

Figure 1. Location of study area, alluvial aquifer ground-water-flow directions, and trichloroethene (TCE) plume of October 2002 

(derived from data obtained from U.S. Air Force, Air Force Center for Environmental Excellence, 1997).

AFP4 and NAS–JRB boundary

EXPLANATION

Concentration of trichloroethene, in micrograms per liter

Generalized direction of gr

Study area boundary

Approximate extent of golf course

5 to 50

50 to 500

500 to 1,000

1,000 to 5,000

5,000 to 15,000

15,000 to 58,000

NAS–JRB precipitation gage

ound-water flow

TEXAS

Fort

Worth

LOCATION MAP

0 0.25 0.5 MILE

32o46'

32o47'

97o26' 97o25' 97o24'

Air Force Plant 4

(AFP4)

Northern lobe

of TCE plume

Central lobe

of TCE plume

Southern lobe

of TCE plume

Trinity

River

Naval Air StationJoint Reserve Base

Carswell Field

(NAS–JRB)

Air Force Plant 4

(AFP4)

Northern lobe

of TCE plume

Central lobe

of TCE plume

Southern lobe

of TCE plume

Trinity

River

Naval Air StationJoint Reserve Base

Carswell Field

(NAS–JRB)

Air Force Plant 4

(AFP4)

Northern lobe

of TCE plume

Central lobe

of TCE plume

Southern lobe

of TCE plume

West

Fork

Trinity

River

Lake Worth

Base from U.S. Air Force, Aeronautical Systems Center
Introduction 3

in-place biodegradation of the plume might have occurred 

upgradient from the demonstration site (RUST Geotech, 1996). 

Background sampling and site characterization during 1996 

indicated a lack of in-place TCE biodegradation at the site. Dissolved oxygen (DO) concentrations typically were greater than 

5 milligrams per liter (mg/L), dissolved organic carbon (DOC) 

concentrations generally were less than 1.5 mg/L, and ratios of 

TCE to its daughter products were relatively stable across the 

site (Jacobs Engineering Group Inc., 1996).

Carbon must be available as an electron donor for biodegradation of chlorinated solvents by means of reductive dechlorination to occur. DO is the first electron acceptor to be used, 

but once DO is depleted, anaerobic microorganisms tend to use 

available electron acceptors in the following order: nitrate, ferric iron, oxyhydroxide (from DO), sulfate, and carbon dioxide 

(Eberts and others, 2003). In the absence of DO or nitrate, chlorinated solvents might act as electron donors in place of ferric 

iron, sulfate, and carbon dioxide. Biodegradation of chlorinated 

solvents, such as TCE, tends to be limited by the availability of 

electron donors because the primary process in the biodegradation of chlorinated solvents under natural conditions is the use 

of chlorinated solvents as electron acceptors (Wiedemeier and 

others, 1996).

Eastern cottonwood trees, which are a type of poplar tree, 

have the potential to add organic carbon to ground water, which 

facilitates in-place microbial reductive dechlorination of TCE. 

According to Hansen (1993), a net addition of soil carbon 

occurs beneath poplar plantations with trees that are older than 

6 to 12 years. Leigh and others (2002) suggest that root turnover 

can provide substrate for degradative bacteria, and Haycock and 

Pinay (1993) report that poplars in a riparian buffer strip in 

southern England contributed enough organic carbon to shallow 

ground water during winter months to cultivate anaerobic conditions and promote complete denitrification of dissolved 

nitrate. In addition to supporting in-place reductive dechlorination, phreatophytes such as eastern cottonwoods might remove 

contaminants from shallow ground water by various processes. 

Tree physiological processes might alter the flow of ground 

water and thereby reduce contaminant mobility by a process 

called phytostabilization. Plants and microbial enzymes can 

bind contaminants into soil by a process called humification. 

Once the contaminants have been removed from the aquifer 

through root systems, trees use enzymes to break down contaminants by a process called phytodegradation. Finally trees can 

remove contaminants by transpiration from leaf surfaces by a 

process called phytovolatilization (McCutcheon and Schnoor, 

2003).

The demonstration project was initiated using a plantation 

of 1-year-old stems harvested from branches of eastern cottonwoods during the dormant season (whips) and a plantation of 

1-year-old eastern cottonwood seedlings (calipers). The U.S. 

Geological Survey (USGS), in cooperation with the U.S. Air 

Force, collected water-level and water-quality data throughout 

the duration of the ongoing demonstration project; data from 

August 1996 to January 2003 are presented in this report. This 

study was conducted to determine water-level variations at the 

phytoremediation demonstration site and to determine the 

effects of the water-level variations on tree growth and mortality and on the biogeochemical system.

Purpose and Scope

This report documents water-level variations at the phytoremediation site during 1996–2003 and describes factors 

affecting water-level variations, such as aquifer properties, precipitation, drawdown attributable to trees, and irrigation. The 

effects of spatial changes in water-level altitudes and groundwater depth on tree growth and mortality during August 1996–

January 2003 are described. Changes in water-level altitudes at 

three instrumented wells during October 1998–July 2002 are 

presented, and these data are compared to the stage of a nearby 

creek and precipitation data over the same period of record. 

This report also presents an evaluation of the effects of groundwater depth on the biogeochemical system including subsurface 

oxidation-reduction processes that relate to TCE degradation.

Description of the Study Area

The study area is 25 acres and is located in the northwestern corner of a golf course in the southeastern part of the Naval 

Air Station-Joint Reserve Base Carswell Field (NAS–JRB) 

(fig. 1). The land surface slopes gently southeastward and 

sharply southwestward from Roaring Springs Road toward 

Farmers Branch Creek (fig. 2). The climate in the study area is 

subhumid, with short, mild winters (daily low temperature averaging about 34 degrees Fahrenheit [°F] in January) and generally long, hot summers (daily high temperature averaging about 

96 °F in July) (Kuniansky and others, 1996). Average annual 

temperature is 65 °F, and average annual precipitation is 32 

inches (in.) (Kuniansky and others, 1996).

The phytoremediation demonstration site, which comprises the study area, is located in the central lobe (fig. 1) of a 

larger TCE ground-water plume that occurs in an alluvial aquifer and originates upgradient from the site at AFP4. When the 

demonstration project was initiated during spring 1996, the 

phytoremediation site consisted of a plantation of 1-year-old 

stems harvested from branches of eastern cottonwoods during 

the dormant season (whips) and a plantation of 1-year-old 

eastern cottonwood seedlings (calipers). Each plantation was 

about 235 feet (ft) long and 50 ft wide and contained 7 rows of 

trees. About 60 trees were planted in each row of the whip plantation, and about 30 trees were planted in each row of the caliper 

plantation. 

Thickness of the alluvial aquifer, which is composed of 

clayey sands and gravels, ranged from 6 to 15 ft, and saturated 

thickness ranged from 1.5 to 5 ft. A relatively impermeable, 

massively bedded, shaley limestone underlies the aquifer. The 

aquifer, which contains three permeable units (shallow, intermediate, and deep), is unconfined and very permeable. The 

general direction of ground-water flow in the alluvial aquifer at 

the site (fig. 3) is to the southeast, which is perpendicular to the 

long sides of the plantations, but locally ground water flows 
4 Water-Level Variations and Their Effects on Tree Growth and Mortality and on the Biogeochemical System, 1996–2003

Figure 2. Land-surface altitudes in study area. 

--

--

Roaring Springs Road

Golf cart path

Golf course

605

604

603

602

601

600

599

598

597

596

596

595

594

593

592

591

590

601

600

599

598

597

589

Farmers Branch Creek

602.72

600.85

601.13

601.39

601.27

597.97

598.23

597.96

596.77

597.44

597.81

597.95 597.32

598.01

596.35

597.45

597.13

596.32

602.05

599.45 599.51

599.41

593.66

592.95

592.73

593.00

597.05

596.00 597.02

594.63

592.54

592.54

592.54

591.65 592.54

592.42

590.87

594.04

604.95

595.02

594.54

595.10 596.38

597.32

592.22

597.03

600.23 600.03

602.41

602.08

598.28

600.95

Approximate extent of tree plantations

EXPLANATION

Well—Number is altitude of land surface, in feet above

NAVD 88

Topographic contour—Shows altitude of land surface, 

in feet above NAVD 88. Contour interval 1 foot; dashed

where inferred

Nested wells—Numbers are altitudes of land surface, in

599.45 feet above NAVD 88; --, not available

599.41

600.23

605

--

N

Base from U.S. Air Force, Aeronautical Systems Center 0 50 100 FEET

toward Farmers Branch Creek in the area southwest of the golf 

cart path. Ground-water depths ranged from 8 to 13 ft below 

land surface at the time of site characterization (1996).

Acknowledgments

This study was supported by the Superfund Innovative 

Technology Evaluation Program of the U.S. Environmental 

Protection Agency, the Environmental Security Technology 

Certification Program of the Department of Defense, and the 

Aeronautical Systems Center, Environmental Management 

Directorate, Wright-Patterson Air Force Base.

Methods

Planting techniques used at the site generally followed 

those established for short-rotation woody crops (Perlack and 

others, 1995). Seven rows were trenched in each plantation to a 

depth of 3 ft, with a spacing of 8 ft between rows. Whips, which 
Figure 3. Location of wells within the study area and location of low hydraulic conductivity zone. 

Roaring Springs Road

Golf cart path

Farmers Branch Creek

Golf course

Whip plantation

Caliper plantation

Hackberry

Hackberry

Oak

19-year-old

Cottonwood

Hackberry

513

514 515

012

013

001

023

008

009

518

517

519

526

525

524

520

522

523

528

527

529

516

521

021

011

017

020

010

022

019

P10

P11

P12

P14

P07

P04

P09

P13

P15

P06

P05

P01

P03

P02

P08

501502503

504505506

510511512

507508509

Approximate extent of Extent of study area—figures A–1 — A–10 (a

EXPLANATION

Well—Number indicateNested wells—Numbe

each of three permeaband deep (bottom to to

Streamflow-gaging staWell with continuous windicates well numberMature tree and type

Approximate extent of (from Eberts and other

513

510511512

518

Oak

General direction of ground-water flow

Base from U.S. Air Force, Aeronautical Systems Center 0 50 100 FEET
6 Water-Level Variations and Their Effects on Tree Growth and Mortality and on the Biogeochemical System, 1996–2003

were about 1.5 ft tall, were planted 4 ft apart within rows, 

whereas calipers, which were greater than 6.5 ft tall, were 

planted 8 ft apart within rows. Irrigation lines and compost 

material were placed in the trenches. After trenches were backfilled, the whips extended 2 in. above the land surface.

The plantings, specifically for the whips, were closely 

spaced to allow for a “natural” self-design of the phytoremediation system. In other words, tree growth and survival were 

dependent upon subsurface heterogeneities. Closely spaced cottonwoods have been shown to have smaller diameters and lower 

survival rates than widely spaced cottonwoods (Krinard, 1985). 

This also was observed at the demonstration site. Whips, which 

were planted twice as closely as calipers, had both a higher mortality rate and a smaller relative diameter (fig. 4) than calipers 

(fig. 5). A drip irrigation system was used to supplement precipitation during the first two growing seasons, and trees were 

watered liberally during the first year, before continuous waterlevel measurements, to encourage development of deep roots. 

Trees were watered only once during 1997. During the first 

3 years of the demonstration project, several tree properties 

were measured, including height, canopy diameter, and trunk 

diameter by Science Applications International Corporation 

(SAIC). Tree properties were not measured again until January 

2003, when trunk diameter was measured by the USGS.

The monitoring system for the site was designed to 

measure incremental changes in site conditions because phytoremediation processes require years to develop. Groundwater-level data were collected from 15 piezometers and 

44 wells, stream stage was measured in Farmers Branch Creek, 

and precipitation was measured at the NAS–JRB (National Climatic Data Center, 2002). All piezometers and wells are 

referred to as wells in this report. The wells were installed 

upgradient from, within, downgradient from, and surrounding 

the tree plantations. Several wells were installed adjacent to 

mature trees, including a 19-year-old (in 1996) cottonwood 

tree. Well depths ranged from 6.55 to 15.19 ft below land surface. Twelve of the wells were installed to make four sets of 

nested wells with three wells in each nest. Each well within each 

nest was screened across one of three permeable units (shallow, 

intermediate, and deep) within the alluvial aquifer. All other 

wells were screened across all three units. Well-construction 

data are in the appendix (table A–1). 

Most of the 59 wells were used primarily for measuring 

water levels. Land-surface altitudes at the wells were determined by automatic levels from a known benchmark. The 

horizontal accuracy of this method typically is within 0.03 ft 

(D.S. Brown, U.S. Geological Survey, oral commun., 2004). 

Water levels in all wells were measured from the top of casing 

using an electric tape. In addition, transducers were placed in 

three wells to continuously measure and record water levels—one upgradient from the tree plantations (well 513), one in 

the whip plantation (well 514), and one in the caliper plantation 

(well 515) (fig. 3). Water-level-altitude data from the three 

instrumented wells (513, 514, and 515), stage data from 

Farmers Branch Creek, and monthly precipitation data from the 

NAS–JRB are presented in figure 6 for the longest time interval 

that was common to all three datasets.

To assess geochemical changes within the aquifer that 

can be attributed to the planted trees, unfiltered ground-water 

samples were collected from wells using a peristaltic pump. 

Wells were pumped for at least 30 minutes before sampling. 

Ground-water samples were analyzed for DO and volatile 

organic compounds (VOCs)—TCE, cis-dichloroethene 

(cis-DCE), trans-dichloroethene (trans-DCE), and vinyl 

chloride (VC).

Decontamination procedures consisted of rinsing the sample cell used for collecting the DO sample with ground water 

from the well prior to sample collection. New Tygon tubing 

(having a low oxygen-diffusion coefficient) was used at each 

well.

During the study, methods for geochemical data collection 

and analysis changed, usually as a result of technological 

advancements. This invariably affects comparability of some 

datasets over time. The concentration of DO was measured in 

the field using the indigo carmine method (Gilbert and others, 

1982). Before June 1998, DO was analyzed using a method 

of visual comparison to a standard for a concentration measurement. After June 1998, a photometer was used to provide a 

quantitative method for determining concentration. Before January 2000, VOCs were analyzed in the field using a Photovac 

10S50 gas chromatograph calibrated for TCE, cis-DCE, transDCE, and VC. All subsequent ground-water samples were analyzed in the laboratory by Severn Trent Laboratories (STL) in 

Arvada, Colo. Spatial variations in ratios of TCE to cis-DCE 

measured prior to January 2000 are useful, but the magnitude of 

the values is not directly comparable to data that were analyzed 

in the laboratory after January 2000. Water-quality results are 

listed in the appendix (tables A–2 – A–6).

Duplicate analyses were done on about 10 percent of 

well samples. Replicate samples from about 10 percent of total 

well samples also were sent to STL for analysis along with 

(typically) at least one trip blank. STL also analyzed method 

blanks and spikes to test for quality assurance and quality 

control within the laboratory (table A–7).

Geochemical data from May 1999, January 2000, and July 

2000 are given less weight than other geochemical data in this 

report because water-level data were not collected during these 

sampling events.

Water-Level Data

Ground-water levels were measured in 59 wells upgradient 

from, within, downgradient from, and surrounding the tree 

plantations during August 1996, October 1997, February 1998, 

June 1998, September 2000, January 2001, July 2001, January 

2002, July 2002, and January 2003. These datasets were used to 

generate a series of maps of ground-water depth and water-level 

altitude, one for each of the measurement dates. The same 

datasets were used in conjunction with topographic data (fig. 2) 

to generate a series of water-level-altitude maps for the same 

time periods (appendix, figs. A–1 – A–10). Water levels were 
Figure 4. Location and relative diameter of existing trees, January 2003, and relations between mean tree diameter and ground-water depth (Septem

mortality and ground-water depth (September 2000) within the whip plantation. 

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Roaring

Springs

Road

501 - 11.55502 - 11.36503 - 10.99

504 - 10.50505 - 10.48

506 - --

514 - 8.70

513 - 13.50

518 - 10.89

517 - 7.75

519 - 8.08

520 - 8.57

523 - 9.24

516 - 12.62

521 - 10.71

P04 - 5.94

P06 - 11.43

P05 - 13.30

P01 - 12.95

P03 - 8.24

P02 - 11.78

522 - no data

8

9

10

11

12

13

7

6

16

55

61

45

37

16

5

2

0256

6-7

MEAN TREE DIAMETER,

IN INCHES

GROUND-WATER DEPTH, 

IN FEET BELOW LAND SURFACE

45 - sample size

341

7-8

8-9

9-10

10-11

11-12

12-13

13-14

0

20406080

100

59

89

72

24

MORTALITY, IN PERCENT24- sample size

6-7

7-8

8-9

9-10

GROUND-WA

IN FEET BELOW 

N

0 25 50 FEET

Base from U.S. Air Force, Aeronautical Systems Center
Figure 5. Location and relative diameter of existing trees and location of trees stunted by beaver activity within the caliper plantation, January 2003. x x x x xx x xx x xx x x xxx Golf cart path 507 - 8.50 508 - -- 509 - 8.42 515 - 8.87 526 - 9.85 525 - 10.34 524 - 8.77 520 - 8.57 519 - 8.08 523 - 9.24 528 - 9.59 527 - 10.74 529 - 10.58 521 - 10.71P14 - 9.09 P07 - 8.80 P13 - 11.32 P15 - 12.43 P06 - 11.43 P08 - 9.38 522- no data Base from U.S. Air Force, Aeronautical Systems Center 13 12 11 11 10 10 9 8 8 9 

N 0 25 50 FEET
Methods 9

Figure 6. Daily mean water-level altitudes for wells 513, 514, and 515, daily mean stream stage at Farmers Branch Creek, and monthly 

precipitation at Naval Air Station-Joint Reserve Base Carswell Field, November 1998–August 2002. WATER-LEVEL ALTITUDE, IN FEET ABOVE NAVD 88

588

590

592

594 Well 515

STREAM STAGE, IN FEET

ABOVE NAVD 88

584.5

585.5

586.5

587.5

588.5

588

590

592

594

WATER-LEVEL ALTITUDE,

IN FEET ABOVE NAVD 88

MONTHLY PRECIPITATION,

IN INCHES

0

2

4

6

8

10

588

590

592

594

WATER-LEVEL ALTITUDE,

IN FEET ABOVE NAVD 88

Jan.

1999

July

1999

Jan.

2000

July

2000

Jan.

2001

July

2001

Jan.

2002

July

2002

Farmers Branch Creek

Well 514

Well 513

Naval Air Station-Joint Reserve 

Base Carswell Field
10 Water-Level Variations and Their Effects on Tree Growth and Mortality and on the Biogeochemical System, 1996–2003

not measured in all wells during the first 2 years. Measurements 

for ground-water depth and water-level altitude at nested wells 

were not used directly in contouring. However, the range of 

measured water levels at nested wells was considered in contouring. For example, if water-level altitudes at a nest ranged 

from 590.73 to 590.96 ft, it was assumed that the actual waterlevel altitude at that point could not be outside that range. This 

same assumption was made with ground-water depths at nested 

wells. Measured ground-water depths and water-level altitudes 

at nested wells are shown in the appendix (figs. A–1 – A–10).

Factors Affecting Water-Level Variations

Water-level data were used to characterize water-level 

variations during 1996–2003. Three primary factors affect 

observed water levels in the study area: aquifer properties, precipitation, and drawdown induced by trees. Irrigation during the 

first two growing seasons also likely affected water levels indirectly by reducing the dependence of trees on water from the 

aquifer; however, technology is not in place to measure those 

effects.

Aquifer Properties

The alluvial aquifer, which is composed of clayey sands 

and gravels, is very thin and ranges from 6 to 15 ft thick; 

saturated thickness ranges from 1.5 to 5 ft. The aquifer is 

unconfined and very permeable. The combination of these 

aquifer properties makes the water levels in the aquifer easily 

influenced by short-term stresses such as large amounts of 

precipitation.

Precipitation

Monthly precipitation data were obtained from a weather 

station at the nearby NAS–JRB (National Climatic Data Center, 

2002). These data were compared to water-level-altitude data 

from the three instrumented wells (513, 514, and 515) and stage 

data from Farmers Branch Creek to evaluate the relative effect 

that precipitation has on water-level variations at the site. There 

is a strong relation between precipitation and ground-water 

altitude at the site (fig. 6). Monthly precipitation totals in excess 

of 6 in. during May 1999, June 2000, and March 2002 appear as 

peaks in the hydrographs for wells 513, 514, and 515 and in the 

stage of Farmers Branch Creek; periods of substantially belownormal precipitation, referred to as droughts in this report, from 

July to September 2000 (0.19 in.) and from July to August 1999 

(0.34 in.) appear as troughs. The highest water levels occurred 

during January–March 2001. Although this peak is coincident 

with moderately heavy precipitation (11.72 in. during that 

period), the magnitude of the peak is greater than peaks from 

May 1999, June 2000, and March 2002, which had comparable 

precipitation totals. Additional precipitation might have fallen 

during January–March 2001 in the contributing area to the site 

that was not observed at the NAS–JRB weather station.

Drawdown Induced by the Trees—Transpiration 

Effects

Drawdown maps were generated to estimate the effects of 

transpiration on ground-water levels. These maps were generated by comparing water levels measured in June 1998 (fig. 7) 

and September 2000 (fig. 8) with water levels measured in February 1998. Water levels measured in February 1998 were used 

in the comparison rather than water levels measured in August 

1996 because 38 additional wells were installed in the area 

between August 1996 and February 1998, and these wells provided more control. Data from the additional wells helped to 

provide a more detailed picture of the drawdown cone. The 

February 1998 data also were used because they provided the 

largest available dormant-season dataset. A ground-water-flow 

model of the site (Eberts and others, 2003) indicated no remnant 

effects of tree transpiration on water-level altitudes during the 

dormant season.

Before drawdowns were computed, water levels in wells at 

the study site were normalized to water levels in wells in the 

surrounding area to account for temporal changes in the water 

table that were unrelated to the planted trees. Specifically, the 

water-level data were adjusted by an amount equal to the difference between water levels at the selected time (June 1998 or 

September 2000) and the water levels during February 1998 in 

wells that were outside the influence of the planted trees. After 

this normalization, the difference between the water levels during the period of interest and February 1998 was computed to 

approximate the drawdown that could be attributed to tree 

transpiration. 

During the peak of the third growing season (June 1998), 

the maximum drawdown that could be attributed to trees, 4.0 to 

4.9 in., was observed between the two plantations. Although a 

drawdown cone could be mapped at this time, the regional 

hydraulic gradient across the demonstration site was to the 

southeast (fig. 7). As a result, most contaminated ground water 

flowed past the downgradient end of the planted area. By the 

end of the fifth growing season (September 2000), both the 

magnitude and extent of the drawdown caused by the trees was 

apparent (fig. 8). Maximum observed drawdown in September 

2000 was about 11.5 in., and the diameter of the drawdown 

cone for areas in which the drawdown exceeded 3.0 in. was 

about 525 ft.

Irrigation

A drip irrigation system was required to supplement precipitation during the first two growing seasons (1996–97). 

Water from the city was used to irrigate the trees during this 

period. Trees were watered liberally during the first year, 

before continuous water-level measurements, to encourage 

development of deep roots. Trees were watered only once 

during 1997. Roots were expected to intercept most or all percolating irrigation water (Licht and Madison, 1994); therefore, 

irrigation was not considered to be an additional source of water 
Effects of Water-Level Variations on Tree Growth and Mortality 11

to the aquifer. However, irrigation might have caused a reduction in the volume of water extracted from the aquifer by the 

trees.

Effects of Water-Level Variations on Tree 

Growth and Mortality

Rates of tree growth at the site were documented to determine the effectiveness of the phytoremediation system. Fiftytwo whips and 51 calipers were measured for tree height, canopy diameter, and trunk diameter several times during the first 

three growing seasons by SAIC. Overall, both whips and calipers showed a substantial increase in all properties measured. 

Only two of the 52 whips and three of the 51 calipers did not 

survive the first 3 years.

Mean trunk diameter increased from less than 1 in. to 

about 2 in. for the whips and from less than 1.5 in. to 3.15 in. for 

the calipers during the first 3 years of the study. Although the 

calipers generally were taller than the whips during the first 

growing season, by the end of the third growing season (1998), 

the whips were about equal to the calipers in height. The whips 

Figure 7. Estimated drawdown attributed to planted trees, June 22, 1998.

587.0

587.5

588.0

589.5

590.0

590.5

589.0

588.5

Farmers Branc Creek

Golf course

Roaring Springs Road

Golf cart path

h

Approximate extent of tree plantations Estimated drawdown, in inches

EXPLANATION

Well

Water-table contour—Shows altitude of water table, 

in feet above NAVD 88. Contour interval 0.5 foot

Nested wells

Less than 0.9

1.0 to 1.9

2.0 to 2.9

3.0 to 3.9

4.0 to 4.9

588.0

0 50 100 FEET

N

Base from U.S. Air Force, Aeronautical Systems Center
12 Water-Level Variations and Their Effects on Tree Growth and Mortality and on the Biogeochemical System, 1996–2003

had a mean height of 18 ft, and the calipers had a mean height 

of 21.7 ft in 1998.

During the fifth growing season (2000) the trees showed 

signs of severe water stress in areas where ground-water depth 

was greater than 11.5 ft below land surface. The fifth growing 

season was characterized by drought conditions (fig. 6) that 

might have amplified the influence of variations in soil structure 

at the site (Hamblin, 1985), differences in root biomass that 

might have resulted from planting strategy variations, and differences in drought tolerance of the different cottonwood varieties that were planted (Tschaplinski and others, 1998; Khurana 

and others, 2000). Because the trees had been irrigated during 

the first 2 years of the study, differences in ability to access 

ground water between whips and calipers might have been 

masked (Persson, 1995).

In January 2003, the diameters of trees in both plantations 

were measured and compared to ground-water depths from 

September 2000, when the site was in the midst of a drought. 

These data are shown in figure 4 (whips) and figure 5 (calipers); 

Figure 8. Estimated drawdown attributed to planted trees, September 19–20, 2000.

588.0

587.5

587.0

586.5

586.0

585.5

585.0

587.0

588.5

588.5

589.0

589.5

590.0

Golf course

Roaring Springs Road

Farmers Branch Creek

Golf cart path

Approximate extent of tree plantations

Estimated drawdown, in inches

EXPLANATION

Well

Water-table contour—Shows altitude of water table, 

in feet above NAVD 88. Contour interval 0.5 foot

Nested wells

Less than 3.0

3.0 to 3.9

4.0 to 4.9

5.0 to 5.9

6.0 to 6.9

7.0 to 7.9

8.0 to 8.9

9.0 to 9.9

10.0 to 10.9

11.0 to 11.5

588.0

0 50 100 FEET Base from U.S. Air Force, Aeronautical Systems Center

N
Effects of Water-Level Variations on Ground-Water Biogeochemistry 13

the figures also indicate which trees were stunted by beaver 

activity and which trees died. 

In the whip plantation, mortality was relatively constant 

between about 25 and 30 percent where ground-water depth 

was less than 10 ft (fig. 4). Mortality increased substantially 

where ground-water depth exceeded 10 ft, and approached 

90 percent for ground-water depths between 12 and 13 ft. This 

is consistent with findings of Stone and Kalisz (1991), who 

reported a maximum rooting depth for eastern cottonwood trees 

of about 11.8 ft. Mean tree diameter also increased as groundwater depth increased; however, this relation did not hold true 

when the sample size within a depth interval was small (less 

than 20 trees), as was the case for depth intervals from 6 to 7 ft, 

12 to 13 ft, and 13 to 14 ft. During periods of drought, larger, 

more deeply rooted trees were more likely to survive than 

smaller neighboring trees. As smaller neighboring trees died, 

this allowed for more growth of the remaining trees because of 

less competition for water, nutrients, and space. 

Almost one-half (49 percent) of the trees in the caliper 

plantation were either stunted by beaver activity (40 percent) or 

altered by human activities (9 percent). These trees could not be 

included in computations related to tree diameter and made 

mortality-based computations problematic. As a result, plots of 

ground-water depth and mean tree diameter and ground-water 

depth and percent mortality were not included in figure 5. In the 

caliper plantation, the mean diameter of trees was about 6.75 in. 

in January 2003 in areas where September 2000 ground-water 

depths were greater than 9 ft, whereas the mean diameter was 

about 8.25 in. in the remainder of the plantation, where groundwater depths were less than 9 ft. These computations do not 

include trees that were stunted by beaver activity.

Effects of Water-Level Variations on 

Ground-Water Biogeochemistry

Results from water-quality sampling provide insight into 

the oxidation-reduction processes occurring in the aquifer and 

effects of water-level variations. The molar ratio of TCE to cisDCE (TCE/cis-DCE) can be used to evaluate degradation of 

TCE to cis-DCE. Decreases in the molar ratio of TCE/cis-DCE 

were observed in samples collected from most wells within and 

downgradient from the planted area over time. Observed 

decreases in TCE/cis-DCE appear to be related to ground-water 

depth. Eberts and others (2003) observed the lowest TCE/cisDCE at the end of the fifth growing season (September 2000) in 

samples collected from wells where ground-water depth was 

less than 10 ft. They also observed that September 2000 samples from wells with the lowest TCE/cis-DCE (wells 511, 514, 

and 515) had the lowest DO concentrations, 0.93 to 1.7 mg/L, 

and the highest DOC concentrations, 1.6 to 1.8 mg/L. Mean DO 

and DOC concentrations for the rest of the September 2000 

samples were 3.9 and 1.1 mg/L, respectively. In contrast, 

TCE/cis-DCE values during the third growing season (June 

1998) were relatively constant, between 3.0 and 4.0, across the 

site except near well 514 and at the wells adjacent to the 19-year 

old cottonwood (fig. 9; fig. 3 for location of cottonwood). This 

indicates that between the third and fifth growing seasons, DOC 

had been introduced into the aquifer by the planted trees, which 

had stimulated reductive dechlorination of TCE. This conclusion is consistent with observations made by Schiff and others 

(1997) who reported that DOC in ground water, which came 

largely from roots and leaching of leaf litter, generally is not 

active in the geochemical system except where ground water is 

shallow enough to interact with recently generated DOC before 

it is consumed by microbes. TCE/cis-DCE, DO, and DOC 

results are in appendix tables A–4 – A–6. 

The relation between ground-water depth and TCE/cisDCE also can be used to explain the increase in mean TCE/cisDCE beneath and downgradient from the planted area between 

January and July 2001. The water table was almost 2 ft higher 

in January than it was in July 2001; therefore, the ground-water 

depth was almost 2 ft greater in July 2001 (figs. 10 and 11). This 

was the greatest measured decline in the water table between 

two sampling events during the study. As a result, shallow 

ground water had greater contact with the microbially active 

root zone in January than in July, and less degradation of 

TCE occurred in July than in January. Microbial communities 

also might have been stressed during July because of changes 

in water levels. Because the labile component of DOC is 

partially derived from leaching of leaf litter, it is also possible 

that TCE/cis-DCE values in January were influenced by 

an increased availability of DOC introduced by infiltrating 

precipitation.

DO data collected during September 2000, January 2001, 

July 2001, January 2002, and July 2002 were grouped into different ground-water-depth intervals and graphed (fig. 12a). The 

boxplots generally show a gradual increase in median DO concentrations as ground-water depth increases. This general trend 

also can be seen in figure 12b, which shows TCE/cis-DCE for 

ground-water-depth intervals for the same dates. In the molar 

ratio graph, there is a pronounced increase in median TCE/

cis-DCE at a ground-water depth of about 6.5 ft, which indicates less degradation of TCE occurs. The dates that were used 

to generate the boxplots were selected because they were the 

only dates that had a consistent method of chemical analysis in 

addition to corresponding ground-water-depth data. 

Data collected from well 516 demonstrates the relation 

between the trees, ground-water depth, and ground-water 

biogeochemistry (fig. 13). In July 2000, the DO concentration 

was less than 1.0 mg/L, and the TCE/cis-DCE also was less 

than 1.0 in samples from well 516. Both of these low values 

indicate that in-place biodegradation was occurring. After July 

2000, a drought occurred in the area that greatly stressed trees 

around well 516. As trees around well 516 began to die, both the 

DO concentration and the TCE/cis-DCE gradually increased to 

values greater than those previously observed. 
14 Water-Level Variations and Their Effects on Tree Growth and Mortality and on the Biogeochemical System, 1996–2003

Figure 9. Lines of equal ground-water depths and (a) molar ratio of trichloroethene (TCE) to cis-dichloroethene (cis-DCE), and 

(b) dissolved oxygen concentrations, June 22, 1998.

--

8

1

2

3

4

6

7

5

9

13

14

15

16

12

11

10

8

1

2

3

4

6

7

9

13

14

15

16

12

11

10

5

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

(b)

(a)

Approximate extent of tree

plantations

EXPLANATION

Line of equal ground-water

depth, in feet below land 

surface—Interval 1 foot; 

dashed where inferred

3.01 to 4.00

2.01 to 3.00

1.01 to 2.00

Less than 1.01

Molar ratio of TCE to

cis-DCE 

Well—Number is molar

ratio of TCE to cis-DCE

Nested wells—Number is

molar ratio of TCE to cis-DCE;

--, not sampled

Approximate extent of tree

plantations

Line of equal ground-water

depth, in feet below land 

surface—Interval 1 foot; 

dashed where inferred

Well—Number is dissolved

oxygen concentration, in

milligrams per liter

EXPLANATION

Greater than 4.0

3.01 to 4.00

2.01 to 3.00

1.01 to 2.00

Less than 1.01

Dissolved oxygen concentration, in milligrams per

liter

3.09

2.90

3.01

3.32

4.7

3.7

4.3

4.3

5

5

Nested wells—Number is

dissolved oxygen concentration, in milligrams per

liter; --, not sampled

--

3.10

3.09

2.90

3.01

3.15 2.08

3.16

3.65

3.57

3.41

3.61

3.69

3.74

3.13

3.32

3.80

3.32

3.57 3.44

3.29

0.25

0.28

1.90

3.57

3.50

3.69

4.1

4.3

4.7

3.7

4.3

1.38 1.68

4.4

3.3

3.6

4.0

3.8 5.0

4.5

1.59

2.9

3.9

2.7

4.3

3.8 4.3

4.8

1.36

0.69

0.75

0.69

4.5

3.8

4.4

2.9

2.23 3.3

0.73

2.5

Base from U.S. Air Force, Aeronautical Systems Center

Base from U.S. Air Force, Aeronautical Systems Center

Well—No data for sampling

event; interpretation (shade

pattern) based on pre- and

post-June 22, 1998 sampling

Well—No data for sampling

event; interpretation (shade

pattern) based on pre- and

post-June 22, 1998 sampling
Effects of Water-Level Variations on Ground-Water Biogeochemistry 15

Figure 10. Lines of equal ground-water depths and (a) molar ratio of trichloroethene (TCE) to cis-dichloroethene (cis-DCE), and 

(b) dissolved oxygen concentrations, January 8, 2001. 

15

14

13

12

11

10

9

8

7

6

6

7

5

4

3

2

1

15

8

7

6

7

6

5

4

3

2

1

9

14

13

12

11

10

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

(b)

(a)

Approximate extent of tree

plantations

EXPLANATION

Line of equal ground-water

depth, in feet below land 

surface—Interval 1 foot; 

dashed where inferred

3.01 to 4.00

Greater than 4.0

2.01 to 3.00

1.01 to 2.00

Less than 1.01

Molar ratio of TCE to

cis-DCE 

Well—Number is molar

ratio of TCE to cis-DCE

Approximate extent of tree

plantations

Line of equal ground-water

depth, in feet below land 

surface—Interval 1 foot; 

dashed where inferred

Well—Number is dissolved

oxygen concentration, in

milligrams per liter

EXPLANATION

Greater than 4.0

3.01 to 4.00

2.01 to 3.00

1.01 to 2.00

Less than 1.01

Dissolved oxygen concentration, in milligrams per

liter

4.28

4.34

4.34

2.27

5.5

5.5

5.8

3.4

5

5

Well—No data for sampling

event; interpretation (shade

pattern) based on pre- and

post-January 8, 2001 sampling

Nested wells—Number is

molar ratio of TCE to cis-DCE;

--, not sampled

Nested wells—Number is

dissolved oxygen concentration, in milligrams per

liter; --, not sampled

Well—No data for sampling

event; interpretation (shade

pattern) based on pre- and

post-January 8, 2001 sampling

Base from U.S. Air Force, Aeronautical Systems Center

Base from U.S. Air Force, Aeronautical Systems Center

4.35

3.82

4.28

4.34

4.34

3.59 0.74

2.51

2.21

2.46

3.02

2.01

3.99

2.79

0.52

0.81

0.30

1.91

2.27

2.21 3.24

3.03

2.68

0.31

0.64

2.01

1.60

1.16

1.14

2.87

2.92

3.14

2.92

Cottonwood tree

Cottonwood tree

4.5

4.8

5.5

5.5

5.8

3.4 0.18

1.60

1.00

3.3

2.9

2.0 4.7

2.3

0.45

0.15

1.56

3.2

3.4 1.20

2.6

2.3

0.89

0.18

1.17

1.30

0.87

0.47

2.6

2.7

2.0

--

--
16 Water-Level Variations and Their Effects on Tree Growth and Mortality and on the Biogeochemical System, 1996–2003

Figure 11. Lines of equal ground-water depths and (a) molar ratio of trichloroethene (TCE) to cis-dichloroethene (cis-DCE), and 

(b) dissolved oxygen concentrations, July 12–13, 2001.

15

16

17

14

13

12

11

10

9

8

7

8

6

5

4

3

2

1

16

17

15

8

7

6

5

4

3

2

1

9

8

9

14

13

12

11

10

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

(b)

(a)

Approximate extent of tree

plantations

EXPLANATION

Line of equal ground-water

depth, in feet below land 

surface—Interval 1 foot; 

dashed where inferred

3.01 to 4.00

Greater than 4.0

2.01 to 3.00

1.01 to 2.00

Less than 1.01

Molar ratio of TCE to

cis-DCE 

Well—Number is molar

ratio of TCE to cis-DCE

Approximate extent of tree

plantations

Line of equal ground-water

depth, in feet below land 

surface—Interval 1 foot; 

dashed where inferred

Well—Number is dissolved

oxygen concentration, in

milligrams per liter

EXPLANATION

3.01 to 4.00

2.01 to 3.00

1.01 to 2.00

Less than 1.01

Dissolved oxygen concentration, in milligrams per

liter

3.99

4.43

4.02

4.02

3.1

3.3

3.3

3.3

5

5

Well—No data for sampling

event; interpretation (shade

pattern) based on pre- and

post-July 12–13, 2001 sampling

Nested wells—Number is

molar ratio of TCE to cis-DCE;

--, not sampled

Nested wells—Number is

dissolved oxygen concentration, in milligrams per

liter; --, not sampled

Well—No data for sampling

event; interpretation (shade

pattern) based on pre- and

post-July 12–13, 2001 sampling

--

--

3.95

4.16

3.99

4.43

4.02

4.01 0.99

2.50

3.61

3.16

3.86

3.60 4.08

3.89

1.32

2.62

1.69

3.53

4.33

4.02 3.41

3.88

2.46 0.53

1.23

3.44

3.50

3.32

3.62

3.78

3.58

3.69

2.8

2.8

3.1

3.3

3.3

1.10 0.53

1.20

1.72

2.0

1.60

1.80 3.1

3.1

0.29

1.28

0.10

1.92

3.3

2.8 1.50

1.80

0.20 N/A

0.85

1.04

1.44

2.13

1.99 0.40

1.20

Base from U.S. Air Force, Aeronautical Systems Center

Base from U.S. Air Force, Aeronautical Systems Center
Figure 12. Boxplots showing distribution of (a) dissolved oxygen concentrations, September 2000–July 2002, and (b) molar ratios of trichloroethene ((cis-DCE), September 2000–July 2002 for selected ground-water depths.

54321

Less 

than 6.50

6.50–7.49 7.50–8.49 8.50–9.49 Greater 

than 9.49

GROUND-WATER DEPTH, 

IN FEET BELOW LAND SURFACE

DISSOLVED OXYGEN CONCENTRATION,

IN MILLIGRAMS PER LITER

0

54321

GROUND-WATER DEPTH, 

IN FEET BELOW LAND SURFACE

MOLAR RATIO OF TCE TO cis-DCE

0

(20)

(18)

(21)

(20)

(18)

(21) (21) (20)

(14)

(1

Less 

than 6.50

6.50–7.49 7.50–8.49 8.50–9.49 Gre

than 

(a) 

EXPLANATION

Number of samplesData value 1.5 to 3.0 times the IQR outside the boxLargest data value within 1.5 times the IQR above the b75th percentileMedian (50th percentile)25th percentileSmallest data value within 1.5 times the IQR below the 

NOTE: Only data from wells shown on map were used for boxplots.

(19)

Interquartile range (IQR)

Farmers Branch Creek

Roaring Springs Road

Golf course

0 50 100 FEET

517

514

519

526

525

524

520 522

523

528

515

527

529

516

521

504505

510511512

507509
Figure 13. Location and relative diameter of remaining trees within the whip plantation near well 516, graphs of dissolved oxygen concentration and 

trichloroethene (TCE) to cis-dichloroethene (cis-DCE) from well 516 samples for selected sampling events, and graph of monthly precipitation from the 

Joint Reserve Base Carswell Field.

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

x

516 - 12.62

P05 - 13.30

02468

10

PRECIPITATION,

IN INCHES

Jan.

1999

July

1999

Jan.

2000

July

2000

Jan

200

012345

MOLAR RATIO OF

TCE TO cis-DCE

012345

DISSOLVED OXYGEN

CONCENTRATION,

IN MILLIGRAMS PER LITER

12

11

13

EXPLANATION

Approximate extent of tree plan

Line of equal ground-water deptland surface—Measured Sept. 11 foot; dashed where inferred 

Represents location and relative Represents location of dead tree

Well—Numbers indicate well nwater depth, in feet below land 2000)

11

x

516 -12.62

Roaring 

Springs 

 Road

Base from U.S. Air Force, Aeronautical Systems Center

0 25 50 FEET
Summary 19

Summary

In 1996, a field-scale phytoremediation demonstration 

project was initiated by the U.S. Air Force at a site in western 

Fort Worth, Tex., near Air Force Plant 4. The primary objective 

of this project was to determine the effectiveness of eastern cottonwoods at reducing the mass of dissolved trichloroethene 

(TCE) that is being transported within an alluvial aquifer. Eastern cottonwoods have the potential to add organic carbon to 

ground water, which facilitates in-place microbial degradation 

of TCE and also might remove contaminants from ground 

water.

The demonstration project was initiated using a plantation 

of 1-year-old stems harvested from branches of eastern cottonwoods during the dormant season (whips) and a plantation of 

1-year-old eastern cottonwood seedlings (calipers). The U.S. 

Geological Survey, in cooperation with the U.S. Air Force, collected water-level and water-quality data throughout the duration of the demonstration project. This study was conducted to 

determine water-level variations at the phytoremediation demonstration site and to determine the effects of the water-level 

variations on tree growth and mortality and on the biogeochemical system.

This report presents spatial changes in water-level altitudes and ground-water depths at periodic sampling events; 

data from August 1996 to January 2003 are presented in this 

report. This report also describes factors affecting water-level 

variations, such as aquifer properties, precipitation, irrigation, 

and drawdown attributable to the trees. This report also evaluates the effects of ground-water depth on tree growth, mortality 

rates, and subsurface oxidation-reduction processes.

Water levels in the study area can be influenced by shortterm stresses such as precipitation because the alluvial aquifer 

is thin, unconfined, and very permeable. A strong relation 

between precipitation and ground-water levels exists. Transpiration effects of the trees also influence water levels through 

induced drawdown. During the peak of the third growing season 

(June 1998), the maximum drawdown that could be attributed 

to trees was 4.0 to 4.9 in. However, by the end of the fifth growing season (September 2000), the maximum observed drawdown was about 11.5 in. A drip irrigation system was required 

to supplement precipitation during the first two growing seasons (1996–97). Roots were expected to intercept most or all 

percolating irrigation water; therefore, irrigation was not considered to be an additional source of water to the aquifer.

Rates of tree growth were documented to gage the effectiveness of the phytoremediation system over time. Overall, 

whips and calipers showed a substantial increase in height, canopy diameter, and trunk diameter during the first 3 years of the 

study. By the fifth growing season (September 2000), the 

heights of calipers varied predictably with ground-water depth; 

the trees showed signs of severe stress in areas where groundwater depth was more than 11.5 ft below land surface. In January 2003, the diameter of each tree was measured and compared 

to ground-water depths from September 2000, when the site 

was in the midst of a drought. Mortality was relatively constant 

between about 25 and 30 percent in the whip plantation where 

ground-water depth was less than 10 ft. Mortality increased 

substantially as ground-water depth exceeded 10 ft and 

approached 90 percent for ground-water depths between 12 and 

13 ft.

TCE/cis-dichloroethene (cis-DCE) decreased during the 

study period in samples from most of the wells within and 

downgradient from the planted area over time. Observed 

decreases in TCE/cis-DCE appear to be related to ground-water 

depth. TCE/cis-DCE during the third growing season (June 

1998) was relatively constant, between 3.0 and 4.0, across the 

site with a few exceptions. By the end of the fifth growing 

season (September 2000), the lowest TCE/cis-DCE values were 

observed in samples from wells where ground-water depths 

were less than 10 ft; these samples contained the lowest 

dissolved oxygen concentrations, 0.93 to 1.7 mg/L, and the 

highest dissolved organic carbon concentrations, 1.6 to 

1.8 mg/L. Between the third and fifth growing seasons, a labile 

fraction of dissolved organic carbon was introduced into the 

aquifer by the planted trees that was capable of stimulating 

reductive dechlorination of TCE. 

References Cited

Eberts, S.M., Harvey, G.J., Jones, S.A., and Beckman, S.W., 

2003, Multiple process assessment for a chlorinated-solvent 

plume, in McCucheon, S.C., and Schnoor, J.L., eds., Phytoremediation—Transformation and control of contaminants: 

Hoboken, N.J., Wiley, p. 589–633.

Gilbert, T.W., Behymer, T.D., and Castaneda, H.B., 1982, 

Determination of dissolved oxygen in natural and waste 

waters: American Laboratory, American Society for Testing 

and Materials ASTM D 888-87, p. 119–134.

Hamblin, A.P., 1985, The influence of soil structure on water 

movement, crop root growth, and water uptake: Advances in 

Agronomy, v. 38, p. 95–157.

Hansen, E.A., 1993, Soil carbon sequestration beneath hybrid 

poplar plantations in the north central United States: Biomass 

and Bioenergy, v. 5, no. 6, p. 431–436.

Haycock, N.E., and Pinay, G., 1993, Groundwater nitrate 

dynamics in grass and poplar vegetated riparian buffer strips 

during winter: Journal of Environmental Quality, v. 22, 

p. 273–278.

Jacobs Engineering Group Inc., 1996, Technology demonstration plan treatability study for plant-enhanced bioremediation of contaminated soil and groundwater—Draft final: Fort 

Worth, Tex., U.S. Air Force Aeronautical Systems Center, 

Air Force Plant 4 [variously paged].

Khurana, D.K., Narljede, S., and Chandrashekhar, M.B., 2000, 

Rooting behavior—An indicator of plantation success 

and growth in poplars in Populus production systems, in

Isebrands, J.G., and Richardson, J., eds., 21st Session of 

the International Poplar Commission, Poplar and willow 

culture—Meeting the needs of society and the environment, 
20 Water-Level Variations and Their Effects on Tree Growth and Mortality and on the Biogeochemical System, 1996–2003

Vancouver, Wash., September 24–28, 2000: St. Paul, Minn., 

U.S. Department of Agriculture, Forest Service, North 

Central Research Station, General Technical Report 

NC–125, p. 93.

Krinard, R.M., 1985, Cottonwood development through 19 

years in a Nelder’s Design: U.S. Department of Agriculture, 

Forest Service, Southern Forest Experiment Station, 

Research Note SO–322, 4 p.

Kuniansky, E.L., Jones, S.A., Brock, R.D., and Williams, M.D., 

1996, Hydrogeology at Air Force Plant 4 and vicinity and 

water quality of the Paluxy aquifer: U.S. Geological Survey 

Water-Resources Investigation Report 96–4091, 41 p. 

Leigh, M.B., Fletcher, J.S., Xiong, Fu, and Schmitz, F.J., 2002, 

Root turnover—An important source of microbial substrates 

in rhizosphere remediation recalcitrant contaminants: Environmental Science and Technology, v. 36, p. 1,579–1,583.

Licht, L.A., and Madison, Mark, 1994, Phytoremediation of 

groundwater at Air Force Plant 4, Carswell. Texas—Innovative technology evaluation report: Proceedings of the 87th 

meeting of the Air and Waste Management Association, June 

19–24, 1994, Cincinnati, Ohio.

McCutcheon, S.C., and Schnoor, J.L., 2003, Overview of 

phytotransformation and control of wastes, in McCucheon, 

S.C., and Schnoor, J.L., eds., Phytoremediation—Transformation and control of contaminants: Hoboken, N.J., Wiley, 

p. 3–58.

National Climatic Data Center, 2002, Daily climatic data: 

U.S. Department of Commerce, National Oceanic and 

Atmospheric Administration, accessed December 16, 2002, 

at URL 

http://www4.ncdc.noaa.gov/cgi-win/

wwcgi.dll?wwDI~StnSrch~StnID~10011153

Perlack, R.D., Wright, L.L., Huston, M.A., and Schramm, 

W.E., 1995, Biomass fuel from woody crops for electric 

power generation: Oak Ridge, Tenn., Oak Ridge National 

Laboratory.

Persson, G., 1995, Willow stand evapotranspiration simulated 

for Swedish soils: Agricultural Water Management, v. 28, 

p. 271–293.

RUST Geotech, 1996, Interim Air Force Plant 4 assessment of 

intrinsic bioremediation: Prepared for U.S. Air Force, Headquarters Aeronautical Systems Center, Wright Patterson 

Air Force Base, Ohio, contract no. DE–AC04–94AL96907 

[variously paged].

Schiff, S.L., Aravena, R., Trumbore, S.E., Hinton, M.J., 

Elgood, R., and Dillon, P.J., 1997, Export of DOC from 

forested catchments on the Precambrian Shield of central 

Ontario—Clues from 13C and 14C: Biogeochemistry, v. 36, 

p. 43–65.

Stone, E.L., and Kalisz, P.J., 1991, The maximum extent of tree 

roots: Forest Ecology and Management, v. 46, p. 77.

Tschaplinski, T.J., Tuskan, G.A., Gebre, G.M., and Todd, D.E., 

1998, Drought resistance of two hybrid Populus clones 

grown in a large-scale plantation: Tree Physiology, v. 18, 

p. 653–658.

U.S. Air Force, Air Force Center for Environmental Excellence, 

1997, Technical report for the ERPIMS 2.0 database model 

of the Environmental Resources Program Information 

Management System: San Antonio, Tex., U.S. Air Force, 

Brooks Air Force Base, 112 p.

Wiedemeier, T.H., Swanson, M.A., Moutox, D.E., Gordon, 

E.K., Wilson, J.T., Wilson, B.H., Kampbell, D.H., Haas, 

P.E., Miller, R.N., Hansen, J.E., and Chapelle, F.H., 1996, 

Technical protocol for evaluating natural attenuation of chlorinated solvents in ground water—Draft revision 1: San 

Antonio, Tex., Air Force Center for Environmental Excellence Technology Transfer Division, Brooks Air Force Base 

[variously paged].
Appendix
Appendix—Figures 23

Figures

Figure A–1. (a) Lines of equal ground-water depths and (b) water-level altitude contours for Aug. 17–22, 1996. 

586.5

587.0

587.5

588.0

588.5

589.0

589.5

590.0

8

8

7

9

9

13

12

11

10

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

(b)

(a)

Approximate extent of tree

plantations

EXPLANATION

Well—Number is ground-water

depth, in feet below land surface

Nested wells—Numbers are

ground-water depths, in feet

below land surface; --, not

available

Approximate extent of tree

plantations

Water-table contour—Shows

altitude of water table, in

feet above NAVD 88. Contour

interval 0.5 foot

Well—Number is altitude of

water level, in feet above

NAVD 88

Nested wells—Numbers are

altitudes of water levels, in

feet above NAVD 88; --, not

available

EXPLANATION

3.09

2.90

3.01

3.32

585.19

586.83

587.06

590.17

7

590.0

13.50

10.68

9.89

11.13

11.02

7.77

8.21

8.06

9.34

9.63

8.34

8.56

8.15

8.01

9.44

8.61

10.14

10.02

12.82

10.28

10.05

10.03

 --

7.76

5.90

5.94

7.97

--

7.96

589.22

590.17

591.24

590.26

590.25

590.20

590.02

589.90

587.43

587.81

589.47

589.39

589.17

590.00

586.91

588.84

586.99

586.30

589.23

589.23 589.40

589.38

589.08

--

589.06

585.19

586.83

587.06

--

Base from U.S. Air Force, Aeronautical Systems Center

Base from U.S. Air Force, Aeronautical Systems Center

Line of equal ground-water

depth, in feet below land 

surface—Interval 1 foot

Well—No data for sampling

event

Well—No data for sampling

event
24 Water-Level Variations and Their Effects on Tree Growth and Mortality and on the Biogeochemical System, 1996–2003

Figure A–2. (a) Lines of equal ground-water depths and (b) water-level altitude contours for Oct. 28, 1997. 

587.5

588.0

588.5

589.0

589.5 590.0

591.0

590.5

590.5

591.5

8

1

2

3

4

6

7

7

5

9

13

14

15

16

12

11

10

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

(b)

(a)

Approximate extent of tree

plantations

EXPLANATION

Approximate extent of tree

plantations

Water-table contour—Shows

altitude of water table, in

feet above NAVD 88. Contour

interval 0.5 foot

Well—Number is altitude of

water level, in feet above

NAVD 88

Nested wells—Numbers are

altitudes of water levels, in

feet above NAVD 88; --, not

available

EXPLANATION

6.74

5.60

5.00

9.58

591.47

591.49

591.50

590.38

7

590.0

Well—Number is ground-water

depth, in feet below land surface

Nested wells—Numbers are

ground-water depths, in feet

below land surface; --, not

available

Line of equal ground-water

depth, in feet below land 

surface—Interval 1 foot

Well—No data for sampling

event

Well—No data for sampling

event

Base from U.S. Air Force, Aeronautical Systems Center

Base from U.S. Air Force, Aeronautical Systems Center

12.34

9.37

9.66

9.90

9.77

6.57 6.82

6.68

8.23

8.48

7.01

7.10

6.70

7.44

8.10

7.23

8.95

8.84

11.38

8.98 8.70

8.68

--

5.44

6.74

5.60

5.00

6.62

6.58 4.35

7.03

7.05

7.50 7.65

5.39

3.41

9.58

10.77 9.80

11.91

11.32

6.80

9.90

590.38

591.48

591.47

591.49

591.50

591.40 591.41

591.28

588.54

588.96

590.80

590.85

590.62

590.57

588.25

590.22

588.18

587.48

590.67

590.53

590.75

590.73

--

588.22

586.21

587.13

588.00

590.43

--

590.44

591.65

587.99

587.49

587.60 588.73

591.93

587.45

589.46

590.23

590.50

590.76

591.48

588.81

--
Appendix—Figures 25

Figure A–3. (a) Lines of equal ground-water depths and (b) water-level altitude contours for Feb. 11, 1998. 

587.5

588.0

588.5

589.0

589.5

590.0

591.0

590.5

591.5

592.0

8

1

2

3

4

6

7

5

9

13

14

15

12

11

10

Roaring Springs R

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

(b)

(a)

oad

Approximate extent of tree

plantations

EXPLANATION

Approximate extent of tree

plantations

Water-table contour—Shows

altitude of water table, in

feet above NAVD 88. Contour

interval 0.5 foot

Well—Number is altitude of

water level, in feet above

NAVD 88

Nested wells—Numbers are

altitudes of water levels, in

feet above NAVD 88; --, not

available

EXPLANATION

9.07

9.31

9.19

8.79

592.06

592.08

592.08

592.06

7

590.0

Well—Number is ground-water

depth, in feet below land surface

Nested wells—Numbers are

ground-water depths, in feet

below land surface; --, not

available

Line of equal ground-water

depth, in feet below land 

surface—Interval 1 foot

--

Base from U.S. Air Force, Aeronautical Systems Center

Base from U.S. Air Force, Aeronautical Systems Center

11.39

8.79

9.07

9.31

9.19

5.99

6.21

6.07

7.82

8.01

6.39

6.45

5.82

6.73

7.51

6.54

8.24

8.19

10.70

8.27 8.01

8.01

5.14

4.98

5.14

3.40

5.94

--

5.90 3.63

6.07

4.35 4.46

6.45

1.89

1.83

5.00

15.24

6.60

6.44

6.82

7.28

6.04

2.99

8.89

9.94

9.80

11.20

10.62

6.11

9.20

591.33

592.06

592.06

592.08

592.08

591.98

592.02

591.89

588.95

589.43

591.42

591.50 591.50

591.28

588.84

590.91

588.89

588.13

591.35

591.24

591.43

591.40

588.52

587.97

587.59

589.60

591.11 -- 591.12

592.37

588.56

588.19 588.08

585.20

590.53

589.04

589.04

589.71

588.42

588.10

588.28 589.10

591.28

589.23

588.14

590.29 590.22

591.21 591.46

592.17

591.75

--
26 Water-Level Variations and Their Effects on Tree Growth and Mortality and on the Biogeochemical System, 1996–2003

Figure A–4. (a) Lines of equal ground-water depths and (b) water-level altitude contours for June 22, 1998. 

588.0

587.5

587.0

589.0

588.5

589.5

590.0

590.5

8

1

2

3

4

6

7

5

9

13

14

15

16

12

11

10

Roaring Springs R

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

(b)

(a)

oad

Approximate extent of tree

plantations

EXPLANATION

Approximate extent of tree

plantations

Water-table contour—Shows

altitude of water table, in

feet above NAVD 88. Contour

interval 0.5 foot

Well—Number is altitude of

water level, in feet above

NAVD 88

Nested wells—Numbers are

altitudes of water levels, in

EXPLANATION

5.43

5.02

5.49

5.25

590.67

590.67

590.70

590.72

7

590.0

Well—Number is ground-water

depth, in feet below land surface

Line of equal ground-water

depth, in feet below land 

surface—Interval 1 foot

Nested wells—Numbers are

ground-water depths, in feet

below land surface; --, not

available

feet above NAVD 88; --, not

available

Base from U.S. Air Force, Aeronautical Systems Center

Base from U.S. Air Force, Aeronautical Systems Center

10.46 12.93

10.72

10.57

7.48

9.61

9.42

12.20

9.78

5.25

6.05

3.28

2.86

6.04

16.71

8.07 8.34

7.35

4.09

10.15

11.44

10.52

12.66 12.14

7.56

10.72

7.36 7.70

8.86

9.16

7.84

7.97

7.57

8.27

8.74

8.07

9.54

9.53

 --

5.99

5.43

5.02

5.49

7.49

 --

7.46

7.00

5.15

7.56

7.24

589.79 590.67

590.67

590.70

590.61

590.53

590.48

587.91

588.28

589.97

589.98

589.74

589.74

587.61

589.38

587.52

586.90

589.85

589.73 589.91

589.88

587.67

587.52

587.71

587.51

589.56

 --

589.56

590.75

587.63

587.39

585.60

589.14

588.01

588.00

588.24

587.46

587.30

588.04 587.03

589.97

588.13

586.88

588.79 589.51

589.75

589.94

590.72

590.23

--

Well—No data for sampling

event

Well—No data for sampling

event
Appendix—Figures 27

Figure A–5. (a) Lines of equal ground-water depths and (b) water-level altitude contours for Oct. 10, 2000. 

588.0

587.5

587.0

586.5

586.0

585.5

585.0

587.0

588.5

588.5

589.0

589.5

590.0

8

1

2

3

4

6

7

5

9

13

14

15

16

17

18

12

11

10

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

(b)

(a)

Approximate extent of tree

plantations

EXPLANATION

Approximate extent of tree

plantations

Water-table contour—Shows

altitude of water table, in

feet above NAVD 88. Contour

interval 0.5 foot

Well—Number is altitude of

water level, in feet above

NAVD 88

Nested wells—Numbers are

altitudes of water levels, in

EXPLANATION

8.14

6.78

6.51

8.24

589.58

590.03

590.28

590.04

590.0

7

Well—Number is ground-water

depth, in feet below land surface

Line of equal ground-water

depth, in feet below land 

surface—Interval 1 foot

Well—No data for sampling

event

Well—No data for sampling

event

Nested wells—Numbers are

ground-water depths, in feet

below land surface; --, not

available

feet above NAVD 88; --, not

available

Base from U.S. Air Force, Aeronautical Systems Center

Base from U.S. Air Force, Aeronautical Systems Center

13.50

10.89

11.55

11.36

10.99

7.75 8.70

8.08

9.85

10.34

8.77

8.57

9.24

9.59

8.87

10.74

10.58

12.62

10.71

10.50

10.48

 --

7.03

8.14

6.78

6.51

8.50

 --

8.42 5.94

8.42

6.15

6.85

3.69

4.02

7.14

18.01

8.59

7.45

9.09 9.38

8.80

5.23

11.32

12.43

11.43

13.30

12.95

8.24

11.78

589.22

589.96

589.58

590.03

590.28

590.22 589.53

589.88

586.92

587.10

589.04

589.38

588.77

586.76

588.58

586.39

585.74

589.43

588.80

588.95

588.93

 --

586.63 584.81

585.95

586.49

588.55

 --

588.60

590.06

586.21

586.39

586.57 584.80

588.73

586.85

586.90

586.94

586.43

587.09

586.01

587.00

588.52

586.99

585.71

587.80 588.60

589.11

589.13

590.04

589.17

5.97
28 Water-Level Variations and Their Effects on Tree Growth and Mortality and on the Biogeochemical System, 1996–2003

Figure A–6. (a) Lines of equal ground-water depths and (b) water-level altitude contours for Jan. 8, 2001. 

588.5

588.0

587.5

587.0

586.5

589.0

589.5

590.0

590.5

591.0

592.0 591.5

8

1

2

3

4

6

6

7

7

5

9

13

14

15

12

11

10

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

(b)

(a)

Approximate extent of tree

plantations

EXPLANATION

Approximate extent of tree

plantations

Water-table contour—Shows

altitude of water table, in

feet above NAVD 88. Contour

interval 0.5 foot

Well—Number is altitude of

water level, in feet above

NAVD 88

Nested wells—Numbers are

altitudes of water levels, in

EXPLANATION

8.82

9.08

8.95

8.54

592.31

592.31

592.32

592.31

590.0

7

Well—Number is ground-water

depth, in feet below land surface

Line of equal ground-water

depth, in feet below land 

surface—Interval 1 foot

Base from U.S. Air Force, Aeronautical Systems Center

Base from U.S. Air Force, Aeronautical Systems Center

Cottonwood tree

11.06

8.54

8.82

9.08

8.95

5.72

5.96

5.79

8.12

8.17

6.03

6.21

5.73

6.23

7.86

5.91

8.85

8.61

10.49

7.92 7.68

7.66

 --

5.34

5.57

5.45

5.29

5.58

 --

5.48 3.70

6.66

4.64

4.70

6.53

1.98

2.10

5.18

15.71

6.86

6.71

7.26 7.43

7.23

3.12

9.32

10.00 8.73

11.06

10.35

5.97

8.92

591.66

592.31

592.31

592.31

592.32

592.25 592.27

592.17

588.65

589.27

591.78

591.74 591.59

591.78

588.49

591.53

588.28

587.71

591.56

591.59

591.77

591.75

 --

588.32

587.38

587.28

587.71

591.47

 --

591.54

592.30

587.97

587.90

587.84 585.12

590.44

588.77

588.86

589.24

588.16

587.83

587.84

588.95

590.09

589.10

587.71

590.23 591.30

591.35 591.73

592.31

592.03

Nested wells—Numbers are

ground-water depths, in feet

below land surface; --, not

available

feet above NAVD 88; --, not

available
Appendix—Figures 29

Figure A–7. (a) Lines of equal ground-water depths and (b) water-level altitude contours for July 12–13, 2001. 

588.5

588.0

587.5

587.0

586.5

586.0

585.5

589.0

589.5

590.0

590.5

8

8

1

2

3

4

6

7

5

9

13

14

15

16

17

12

11

10

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

(b)

(a)

Approximate extent of tree

plantations

EXPLANATION

Approximate extent of tree

plantations

Water-table contour—Shows

altitude of water table, in

feet above NAVD 88. Contour

interval 0.5 foot

Well—Number is altitude of

water level, in feet above

NAVD 88

Nested wells—Numbers are

altitudes of water levels, in

EXPLANATION

6.94

6.57

5.92

7.54

590.70

590.72

590.71

590.67

7

590.0

Nested wells—Numbers are

ground-water depths, in feet

below land surface; --, not

available

feet above NAVD 88; --, not

available

Well—Number is ground-water

depth, in feet below land surface

Line of equal ground-water

depth, in feet below land 

surface—Interval 1 foot

Base from U.S. Air Force, Aeronautical Systems Center

Base from U.S. Air Force, Aeronautical Systems Center

12.83

10.18

10.43

10.67

10.56

7.23 7.72

7.37

9.26

9.55

7.75

7.88 7.41

8.14

9.10

7.76

10.40

9.84

12.18

9.66

9.44

9.44

 --

6.32 6.94

6.57

5.92

7.54

 --

7.43 5.28

7.70

5.52

5.36 6.22

3.40

3.11

6.33

17.03

7.86

7.85

8.34 8.52

8.56

4.34

10.58

11.49

10.41

12.63 12.03

7.54

10.67

589.89

590.67

590.70

590.72

590.71

590.74

590.51

590.59

587.51

587.89

590.06

590.07 589.91

589.87

587.25

589.69

586.73

586.48

589.87

589.85

590.01

589.97

587.34

586.01

586.16

587.08

589.51

 --

589.59

590.72

586.93

587.02

587.18

585.43

589.02

587.76

587.71

587.92

587.16

586.69

586.76 587.86

588.76

587.88

586.45

588.74 589.62

589.78

590.05

590.74

590.28

 --
30 Water-Level Variations and Their Effects on Tree Growth and Mortality and on the Biogeochemical System, 1996–2003

Figure A–8. (a) Lines of equal ground-water depths and (b) water-level altitude contours for Jan. 15–16, 2002. 

588.5

588.0

587.5

587.0

586.0

586.5

589.0

589.5 590.0

590.5

8

8

1

2

3

4

6

7

5

9

13

14

15

16

17

12

11

10

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

(b)

(a)

Approximate extent of tree

plantations

EXPLANATION

Approximate extent of tree

plantations

Water-table contour—Shows

altitude of water table, in

feet above NAVD 88. Contour

interval 0.5 foot

Well—Number is altitude of

water level, in feet above

NAVD 88

Nested wells—Numbers are

altitudes of water levels, in

EXPLANATION

6.24

6.05

5.78

7.63

590.60

590.68

590.63

590.62

590.0

7

Well—Number is ground-water

depth, in feet below land surface

Line of equal ground-water

depth, in feet below land 

surface—Interval 1 foot

Nested wells—Numbers are

ground-water depths, in feet

below land surface; --, not

available

feet above NAVD 88; --, not

available

Base from U.S. Air Force, Aeronautical Systems Center

Base from U.S. Air Force, Aeronautical Systems Center

12.90

10.23

10.53

10.71

10.64

7.26 7.60

7.48

9.09

9.34

7.71

7.77 7.11

8.10

9.01

7.53

10.13

9.71

12.21

9.69 9.44

9.42

6.20 6.24

6.05

5.78

7.32

 --

7.22 5.33

7.62

5.43

5.25

2.50

3.02

6.22

17.21

7.79

7.27

8.26 8.46

8.27

4.20

10.51

11.50

10.54

12.73

12.14

7.63

10.72

589.82

590.62

590.60

590.68

590.63

590.71

590.63

590.48

587.68

588.10

590.10

590.18

590.21

589.91

587.34

589.92

587.00

586.61

589.84

589.82 590.01

589.99

587.46

586.71

586.68

587.22

589.73

589.80

590.67

587.01

587.11

587.29

589.92

587.85

587.82

587.74

587.23

587.27

586.84 587.92

589.05

588.02

586.52

588.73 589.49

589.68 589.94

590.65

590.23

 --

 --

 --

Well—No data for sampling

event

Well—No data for sampling

event
Appendix—Figures 31

Figure A–9. (a) Lines of equal ground-water depths and (b) water-level altitude contours for July 18–19, 2002. 

588.5

588.0

587.5

587.0

586.0

586.5

589.0

589.5

590.0 590.5

8

8

1

2

3

4

6

7

5

9

13

14

15

16

12

11

10

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

(b)

(a)

Approximate extent of tree

plantations

EXPLANATION

Approximate extent of tree

plantations

Water-table contour—Shows

altitude of water table, in

feet above NAVD 88. Contour

interval 0.5 foot

Well—Number is altitude of

water level, in feet above

NAVD 88

Nested wells—Numbers are

altitudes of water levels, in

EXPLANATION

6.07

5.88

5.56

7.49

590.80

590.80

590.83

590.81

590.0

7

Nested wells—Numbers are

ground-water depths, in feet

below land surface; --, not

available

feet above NAVD 88; --, not

available

12.68

10.04

10.33

10.59

10.44

7.22 7.46

7.36

8.79

9.13

7.55

7.52

7.03

7.93

8.75

7.37

9.94

9.41

11.98

9.49 9.27

9.26

5.99

6.07

5.88

5.56

7.18

--

5.17 7.05

7.34

5.20

5.03

2.85

2.75

5.94

16.70

7.56

7.12

8.26

8.32

3.96

10.20

11.29

10.18

12.47

11.90

7.49

10.56

8.09

590.37

590.81

590.80

590.80

590.83

590.75 590.58

590.60

587.98

588.31

590.26

590.43

590.29

590.08

587.60

590.08

587.19

586.91

590.07

590.02 590.18

590.15

587.67 586.88

586.85

587.44

589.87

589.97

590.83

587.29

587.34

587.51

589.57

588.12

588.10

588.25

587.46

587.42

587.01

588.12

589.00

588.26

586.83

588.94 589.85

589.94

590.18

590.79

590.39

--

--

--

Well—Number is ground-water

depth, in feet below land surface

Line of equal ground-water

depth, in feet below land 

surface—Interval 1 foot

Base from U.S. Air Force, Aeronautical Systems Center

Base from U.S. Air Force, Aeronautical Systems Center

Well—No data for sampling

event

Well—No data for sampling

event
32 Water-Level Variations and Their Effects on Tree Growth and Mortality and on the Biogeochemical System, 1996–2003

Figure A–10. (a) Lines of equal ground-water depths and (b) water-level altitude contours for Jan. 14–15, 2003. 

588.5

588.0

587.5

587.0

586.5

589.0

589.5

590.0

590.5

591.0

591.5

8

1

2

3

4

6

7

7

5

9

13

14

15

12

11

10

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

Roaring Springs Road

Golf cart path

Golf course

Farmers Branch Creek

N

0 50 100 FEET

(b)

(a)

7

590.0

Approximate extent of tree

plantations

EXPLANATION

Approximate extent of tree

plantations

Water-table contour—Shows

altitude of water table, in

feet above NAVD 88. Contour

interval 0.5 foot

Well—Number is altitude of

water level, in feet above

NAVD 88

Nested wells—Numbers are

altitudes of water levels, in

EXPLANATION

5.46

5.21

5.18

9.43

591.41

591.38

591.43

591.42

Nested wells—Numbers are

ground-water depths, in feet

below land surface; --, not

available

feet above NAVD 88; --, not

available

Well—Number is ground-water

depth, in feet below land surface

Line of equal ground-water

depth, in feet below land 

surface—Interval 1 foot

Base from U.S. Air Force, Aeronautical Systems Center

Base from U.S. Air Force, Aeronautical Systems Center

15.95

11.92

11.31 11.37

12.06 9.72

10.01

9.84

9.43

9.92

6.85

6.64 6.52

6.67

6.28

8.63

8.61

6.99

7.24

8.82

9.60

10.43

9.50

6.49

6.51

 --

6.41

6.90

8.66

7.72

7.80

4.54

2.35

3.53 5.53

2.39

7.21

6.97 7.18

8.48

7.79

8.41

9.90

9.09

5.46

5.21

5.18

5.62

4.90 4.85

6.79

589.00

587.23

587.13

587.63

589.80 590.43

590.49

590.76 590.68

590.66 591.41

591.38

591.43

591.42

590.69

590.97

590.96

591.04

590.82

590.80

591.03

591.43

590.96

590.54

590.61

590.91

588.78

589.60

591.33 591.71

591.29

591.46

590.07

588.69 588.51

588.48 588.04

587.49

587.52

587.82

587.64 587.69

584.86

587.94

588.58 588.29 587.31

587.36

587.81

587.66

16

 --

 --

 --
Appendix—Tables 33

Tables Table A–1. Well-construction data—Continued.

Well ID Abbreviated

well ID

Measured well depth

below top of casing

(feet)

Land-surface altitude

(feet above NAVD 88)

Top of screened interval

(feet below land surface)

Bottom of screened interval

(feet below and surface)

WCOETA001 P01 -- 602.07 -- --

WCOETA002 P02 4.10 600.95 -- --

WCOETA003 P03 -- 598.28 -- --

WCOETA004 P04 8.90 595.66 -- --

WCOETA005 P05 -- 602.41 -- --

WCOETA006 P06 -- 600.03 -- --

WCOETA007 P07 -- 597.32 -- --

WCOETA008 P08 -- 596.38 -- --

WCOETA009 P09 -- 592.22 -- --

WCOETA010 P010 7.35 593.66 -- --

WCOETA011 P011 -- 595.02 -- --

WCOETA012 P012 -- 594.54 -- --

WCOETA013 P013 -- 597.03 -- --

WCOETA014 P014 -- 595.1 -- --

WCOETA015 P015 -- 600.23 -- --

WJEGTA501 501 14.30 601.08 14.18 14.51

WJEGTA502 502 13.54 601.39 12.28 12.61

WJEGTA503 503 12.28 601.27 13.28 13.61

WJEGTA504 504 15.18 599.45 12.04 12.37

WJEGTA505 505 14.17 599.41 11.38 11.71

WJEGTA506 506 10.20 -- 10.72 11.05

WJEGTA507 507 14.65 597.05 9.58 9.91

WJEGTA508 508 13.65 -- 10.88 11.21

WJEGTA509 509 12.69 597.02 10.51 10.84

WJEGTA510 510 7.90 592.95 8.92 9.25

WJEGTA511 511 7.43 597.73 7.68 8.01

WJEGTA512 512 6.55 592.73 6.88 7.21

WJEGTA513 513 17.69 602.72 6.28 6.61

WJEGTA514 514 12.50 598.23 10.64 14.64

WJEGTA515 515 14.69 597.45 5.35 9.35

WJEGTA516 516 18.70 602.05 7.5 11.5

WJEGTA517 517 13.55 597.97 11.53 15.53

WJEGTA518 518 12.76 600.85 6.81 11.21

WJEGTA519 519 9.47 597.62 8.97 12.97

WJEGTA520 520 9.32 597.95 5.44 9.44

WJEGTA521 521 13.59 599.51 7.44 9.44

WJEGTA522 522 9.60 597.32 11.35 13.35

WJEGTA523 523 13.50 598.01 7.44 9.44

WJEGTA524 524 13.57 597.81 7.45 9.45

WJEGTA525 525 14.87 597.44 8.83 10.83

Table A–1. Well-construction data. 

[--, not available] 
34 Water-Level Variations and Their Effects on Tree Growth and Mortality and on the Biogeochemical System, 1996–2003

WJEGTA526 P26 12.84 596.77 7.59 11.59

WJEGTA527 P27 11.26 597.13 11.19 13.19

WJEGTA528 P28 12.09 596.35 7.28 11.28

WJEGTA529 P29 11.00 596.32 7.83 12.23

WUSGSTA001 001 10.00 594.79 9.06 11.06

WUSGSTA002 002 8.58 592.31 6.00 8.00

WUSGSTA003 003 6.66 584.27 4.33 6.66

WUSGSTA004 004 9.17 588.01 7.90 9.17

WUSGSTA005 005 11.33 586.27 9.00 11.00

WUSGSTA006 006 9.25 578.79 7.00 9.00

WUSGSTA007 007 14.00 593.3 6.80 11.80

WUSGSTA008 008 14.50 590.74 11.50 13.50

WUSGSTA009 009 5.50 592.42 3.00 5.50

WUSGSTA010 010 5.50 590.87 2.50 5.50

WUSGSTA011 011 7.00 592.54 4.20 6.20

WUSGSTA012 012 13.00 597.22 9.30 11.30

WUSGSTA013 013 17.00 600.61 13.50 15.50

WUSGSTA014 014 17.50 599.53 14.50 16.50

WUSGSTA015 015 15.50 603.3 12.50 14.50

WUSGSTA016 016 10.00 600.42 7.50 9.50

WUSGSTA017 017 7.92 592.54 5.42 7.42

WUSGSTA018 018 16.00 598.23 12.95 14.95

WUSGSTA019 019 19.80 604.95 17.30 19.30

WUSGSTA020 020 10.70 594.63 8.20 102.00

WUSGSTA021 021 7.50 590.43 4.50 6.50

WUSGSTA022 022 8.75 594.04 6.25 8.25

WUSGSTA023 023 7.30 590.23 4.80 6.80

Table A–1. Well-construction data—Continued.

Well ID Abbreviated

well ID

Measured well depth

below top of casing

(feet)

Land-surface altitude

(feet above NAVD 88)

Top of screened interval

(feet below land surface)

Bottom of screened interval

(feet below and surface)
Appendix—Tables 35

Table A–2. Trichloroethene concentrations from six sampling events.

[In micrograms per liter (μg/L); to convert to micromoles per liter, divide by atomic mass of trichloroethene, 131.38 μg/L; --, not sampled; Q, elevated reporting 

limit] 

Sampling event

Well ID June 1998 Sept. 2000 Jan. 2001 July 2001 Jan.–Feb. 2002 July 2002

WCOETA002 -- -- -- -- 170 170

WCOETA004 -- -- 210 270 200 170

WCOETA006 -- -- -- -- -- 170

WCOETA010 -- -- 160 110 120 130

WJEGTA501 460 -- 180 200 170 160

WJEGTA502 510 160 200 240 140 170

WJEGTA503 530 -- 200 180 150 180

WJEGTA504 560 -- 150 180 140 130

WJEGTA505 490 -- 160 200 170 120

WJEGTA507 440 -- 150 210 190 150

WJEGTA508 450 -- 130 190 160 180

WJEGTA509 500 -- 110 180 150 150

WJEGTA510 48 -- 32 -- 7.8 2

WJEGTA511 64 45 64 41 43 11

WJEGTA512 360 -- 150 100 77 110

WJEGTA513 -- -- 230 230 150 180

WJEGTA514 423 120 72 110 130 150

WJEGTA515 390 60 34 160 51 130

WJEGTA516 540 240 160 270 230 170

WJEGTA517 470 -- 190 250 190 Q200

WJEGTA518 420 200 150 220 190 170

WJEGTA519 600 190 180 230 140 130

WJEGTA520 450 -- 150 200 170 190

WJEGTA521 580 -- 180 240 170 180

WJEGTA522 -- -- 200 210 190 180

WJEGTA523 500 -- 170 190 190 160

WJEGTA524 600 220 180 230 180 180

WJEGTA525 460 -- 140 210 130 150

WJEGTA526 490 240 150 220 180 160

WJEGTA527 540 -- 40 110 12 Q51

WJEGTA528 380 -- 24 75 1.2 47

WJEGTA529 500 -- 150 220 170 160

WUSGSTA011 -- -- 170 140 150 150

WUSGSTA017 -- -- 170 160 150 130

WUSGSTA020 -- -- 170 200 150 160

WUSGSTA021 -- -- -- -- 75 --
36 Water-Level Variations and Their Effects on Tree Growth and Mortality and on the Biogeochemical System, 1996–2003

Table A–3. cis-Dichloroethene concentrations from six sampling events. 

[In micrograms per liter (μg/L); to convert to micromoles per liter, divide by atomic mass of cis-dichloroethene, 96.94 μg/L; --, not sampled] 

Sampling event

Well ID Jun. 1998 Sept. 2000 Jan. 2001 July 2001 Jan.–Feb. 2002 July 2002

WCOETA002 -- -- -- -- 28 29

WCOETA004 -- -- 54 55 53 38

WCOETA006 -- -- -- -- -- 31

WCOETA010 -- -- 44 33 57 46

WJEGTA501 110 -- 31 37 30 26

WJEGTA502 130 33 34 40 27 28

WJEGTA503 130 -- 34 33 30 29

WJEGTA504 120 -- 50 39 45 26

WJEGTA505 110 -- 39 38 35 21

WJEGTA507 91 -- 69 45 36 28

WJEGTA508 95 -- 83 40 33 33

WJEGTA509 100 -- 71 40 33 30

WJEGTA510 140 -- 77 -- 83 49

WJEGTA511 170 120 74 57 59 53

WJEGTA512 140 -- 55 60 43 44

WJEGTA513 -- -- 39 43 33 30

WJEGTA514 150 47 72 82 51 47

WJEGTA515 92 24 31 45 25 32

WJEGTA516 120 47 52 46 42 30

WJEGTA517 110 -- 39 46 44 30

WJEGTA518 100 39 29 39 30 26

WJEGTA519 140 53 53 68 37 45

WJEGTA520 92 -- 55 41 32 31

WJEGTA521 120 -- 41 44 30 29

WJEGTA522 -- -- 37 38 33 30

WJEGTA523 100 -- 45 36 38 28

WJEGTA524 130 48 44 44 37 35

WJEGTA525 95 -- 42 49 32 33

WJEGTA526 99 47 50 45 40 33

WJEGTA527 120 -- 100 48 41 16

WJEGTA528 75 -- 34 42 1.9 15

WJEGTA529 97 -- 58 46 44 33

WUSGSTA011 -- -- 43 28 44 32

WUSGSTA017 -- -- 40 33 50 43

WUSGSTA020 -- -- 43 39 42 35

WUSGSTA021 -- -- -- -- 55 --
Appendix—Tables 37

Table A–4. Molar ratios of trichloroethene to cis-dichloroethene from six sampling events. 

[--, not sampled] 

Sampling event

Well ID June 1998 Sept. 2000 Jan. 2001 July 2001 Jan.–Feb. 2002 July 2002

WCOETA002 -- -- -- -- 4.48 4.33

WCOETA004 -- -- 2.87 3.62 2.78 3.30

WCOETA006 -- -- -- -- -- 4.05

WCOETA010 -- -- 2.68 2.46 1.55 2.09

WJEGTA501 3.09 -- 4.28 3.99 4.18 4.54

WJEGTA502 2.89 3.58 4.34 4.43 3.83 4.48

WJEGTA503 3.01 -- 4.34 4.02 3.69 4.58

WJEGTA504 3.44 -- 2.21 3.41 2.30 3.69

WJEGTA505 3.29 -- 3.03 3.88 3.58 4.22

WJEGTA507 3.57 -- 1.60 3.44 3.89 3.95

WJEGTA508 3.50 -- 1.16 3.50 3.58 4.02

WJEGTA509 3.69 -- 1.14 3.32 3.35 3.69

WJEGTA510 .25 -- .31 -- .07 .03

WJEGTA511 .28 .28 .64 .53 .54 .15

WJEGTA512 1.90 -- 2.01 1.23 1.32 1.84

WJEGTA513 -- -- 4.35 3.95 3.35 4.43

WJEGTA514 2.08 1.88 .74 .99 1.88 2.35

WJEGTA515 3.13 1.84 .81 2.62 1.51 3.00

WJEGTA516 3.32 3.77 2.27 4.33 4.04 4.18

WJEGTA517 3.15 -- 3.59 4.01 3.19 4.92

WJEGTA518 3.10 3.78 3.82 4.16 4.67 4.82

WJEGTA519 3.16 2.65 2.51 2.50 2.79 2.13

WJEGTA520 3.61 -- 2.01 3.60 3.92 4.52

WJEGTA521 3.57 -- 3.24 4.02 4.18 4.58

WJEGTA522 -- -- 3.99 4.08 4.25 4.43

WJEGTA523 3.69 -- 2.79 3.89 3.69 4.22

WJEGTA524 3.41 3.38 3.02 3.86 3.59 3.79

WJEGTA525 3.57 -- 2.46 3.16 3.00 3.35

WJEGTA526 3.65 3.77 2.21 3.61 3.32 3.58

WJEGTA527 3.32 -- .30 1.69 .22 2.35

WJEGTA528 3.74 -- .52 1.32 .47 2.31

WJEGTA529 3.80 -- 1.91 3.53 2.85 3.58

WUSGSTA011 -- -- 2.92 3.69 2.52 3.46

WUSGSTA017 -- -- 3.14 3.58 2.21 2.23

WUSGSTA020 -- -- 2.92 3.78 2.64 3.37

WUSGSTA021 -- -- -- -- 1.01 --
38 Water-Level Variations and Their Effects on Tree Growth and Mortality and on the Biogeochemical System, 1996–2003

Table A–5. Dissolved oxygen concentrations from six sampling events. 

[In milligrams per liter; --, not sampled] 

Sampling event

Well ID June 1998 Sept. 2000 Jan. 2001 July 2001 Jan.–Feb. 2002 July 2002

WCOETA002 -- -- -- -- 3.8 2.6

WCOETA004 -- -- 3.2 0.40 1.11 .49

WCOETA006 -- -- -- -- -- 1.80

WCOETA010 1.36 -- 2.3 .20 1.01 .20

WJEGTA501 4.7 -- 5.5 3.1 3.5 2.6

WJEGTA502 3.7 4.3 5.5 3.3 3.4 2.8

WJEGTA503 4.3 -- 5.8 3.3 4.3 2.8

WJEGTA504 4.3 -- 1.2 1.50 2.08 2.6

WJEGTA505 4.8 -- 2.6 1.80 1.90 2.1

WJEGTA507 4.5 -- 1.3 1.44 1.30 2.24

WJEGTA508 3.8 -- .87 2.13 2.06 1.90

WJEGTA509 4.4 -- .47 1.99 1.02 1.24

WJEGTA510 .69 -- .89 -- 1.60 .44

WJEGTA511 .75 .93 .18 .85 1.11 .80

WJEGTA512 .69 -- 1.17 1.04 1.03 .37

WJEGTA513 4.1 -- 4.5 2.8 4.1 3.1

WJEGTA514 1.68 1.7 .18 .53 .34 .59

WJEGTA515 2.9 1.6 .15 1.28 1.07 1.10

WJEGTA516 4.3 3.8 3.2 3.3 2.0 3.01

WJEGTA517 1.38 -- 3.4 1.10 3.1 1.52

WJEGTA518 4.3 4.8 4.8 2.8 3.2 1.50

WJEGTA519 4.4 3.2 1.6 1.20 .63 1.80

WJEGTA520 3.8 -- 2.0 1.80 1.70 1.14

WJEGTA521 3.8 -- 3.4 2.8 1.90 2.6

WJEGTA522 5.0 -- 4.7 3.1 -- 1.41

WJEGTA523 4.5 -- 2.3 3.1 -- 2.1

WJEGTA524 4.0 4.2 2.9 1.60 -- .30

WJEGTA525 3.6 -- 3.3 2.0 -- 1.30

WJEGTA526 3.3 3.2 1.00 1.72 -- .83

WJEGTA527 3.9 -- 2.8 .10 -- .80

WJEGTA528 1.59 -- .45 .29 -- 1.30

WJEGTA529 2.7 -- 1.56 1.92 -- 1.14

WUSGSTA011 3.3 -- 2.0 1.53 -- .60

WUSGSTA017 2.23 -- 2.7 .76 -- .33

WUSGSTA020 2.9 -- 2.6 1.20 -- .90

WUSGSTA021 .73 -- -- -- -- --

WUSGSTA022 2.5 -- -- -- -- --
Appendix—Tables 39

Table A–6. Dissolved organic carbon concentrations from September 2000 sampling event. 

[In milligrams per liter] 

Table A–7. Quality-control results for trichloroethene (TCE), cis-dichloroethene (cis-DCE), and molar ratios of TCE to cis-DCE 

(TCE/cis-DCE) for four of six sampling events. 

[dup, duplicate sample; μg/L, micrograms per liter] 

Well ID Concentration

WJEGTA502 1.1

WJEGTA511 1.7

WJEGTA514 1.8

WJEGTA515 1.6

WJEGTA516 0.9

WJEGTA518 1.1

WJEGTA519 1.3

WJEGTA524 1.0

WJEGTA526 1.2

January 2001 

Well WJEGTA509 dup TCE - 130 μg/L; cis-DCE - 72 μg/L; TCE/cis-DCE - 1.33

Field blank neither cis-DCE nor TCE were detected

Method blank (3) neither cis-DCE nor TCE were detected

July 2001

Well WJEGTA502 dup TCE - 250 μg/L; cis-DCE - 40 μg/L; TCE/cis-DCE - 4.61

Well WJEGTA511 dup TCE - 41 μg/L; cis-DCE - 64 μg/L; TCE/cis-DCE - 0.47

Well WJEGTA525 dup TCE - 200 μg/L; cis-DCE - 49 μg/L; TCE/cis-DCE - 3.01

Field blank neither cis-DCE nor TCE were detected

Method blank (3) neither cis-DCE nor TCE were detected

January–February 2002

Well WJEGTA515 dup TCE - 51 μg/L; cis-DCE - 25 μg/L; TCE/cis-DCE - 1.51

Well WJEGTA527 dup TCE - 11 μg/L; cis-DCE - 40 μg/L; TCE/cis-DCE - 0.20

Field blank neither cis-DCE nor TCE were detected

Method blank (3) neither cis-DCE nor TCE were detected

July 2002

Well WJEGTA511 dup TCE - 8.9 μg/L; cis-DCE - 48 μg/L; TCE/cis-DCE - 0.14

Well WJEGTA518 dup TCE - 160 μg/L; cis-DCE - 25 μg/L; TCE/cis-DCE - 4.72

Field blank neither cis-DCE nor TCE were detected

Method blank (3) neither cis-DCE nor TCE were detected
Prepared by the Texas District Office:

U.S. Geological Survey

8027 Exchange Drive

Austin, TX 78754–4733

Information regarding water resources in Texas is available at URL

http: //tx.usgs.gov/