U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2009–5085

Prepared in cooperation with East Tennessee Natural Gas and the

U.S. Fish and Wildlife Service

Continuous Turbidity Monitoring in the Indian Creek 

Watershed, Tazewell County, Virginia, 2006–08
Cover photograph. The water-quality monitoring station located on Indian Creek above Route 631 near Cedar Bluff, Virginia; 

view looking upstream.
Continuous Turbidity Monitoring in the 

Indian Creek Watershed, Tazewell County, 

Virginia, 2006–08

By Douglas L. Moyer and Kenneth E. Hyer

Prepared in cooperation with East Tennessee Natural Gas and the 

U.S. Fish and Wildlife Service

Scientific Investigations Report 2009–5085

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2009

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Suggested citation:

Moyer, D.L., and Hyer, K.E., 2009, Continuous turbidity monitoring in the Indian Creek watershed, Tazewell County, 

Virginia, 2006–08: U.S. Geological Survey Scientific Investigations Report 2009–5085, 42 p.

ISBN 978–1–4113–2415–2 
iii

Contents

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

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

Purpose and Scope ..............................................................................................................................4

Description of Study Area ...................................................................................................................4

Jewell Ridge Pipeline Construction..........................................................................................4

Methods of Investigation..............................................................................................................................6

Continuous Water-Quality Monitor Installation...............................................................................6

Indian Creek Network .................................................................................................................7

Unnamed Tributary Network......................................................................................................7

Continuous Water-Quality Monitor Maintenance.........................................................................10

Continuous Stream Gage Operation................................................................................................10

Data Analysis.......................................................................................................................................10

Continuous Water-Quality Data Collection............................................................................10

Assessment of Long-Term Turbidity Patterns .......................................................................10

Turbidity-Input Warning System..............................................................................................12

Water-Quality Patterns in Indian Creek and the Unnamed Tributary .................................................12

Indian Creek Streamflow...................................................................................................................12

Instream Turbidity Conditions ...........................................................................................................15

Long-Term Patterns of Turbidity in Indian Creek and the Unnamed Tributary .........................15

Utility of the Turbidity-Input Warning System................................................................................26

Conceptual Model for Indian Creek Turbidity Patterns................................................................28

Study Limitations.................................................................................................................................31

Summary and Conclusions.........................................................................................................................31

Acknowledgments.......................................................................................................................................32

References Cited..........................................................................................................................................32

Appendixes ...................................................................................................................................................35
iv

Figures

1–3. Maps showing— 

 1. The Jewell Ridge Lateral natural gas pipeline, Virginia .................................................3

 2. The Indian Creek watershed, Tazewell County, Virginia ................................................5

 3. The Indian Creek and unnamed tributary monitoring network, 

Tazewell County, Virginia......................................................................................................6

4–5. Photographs showing—

 4. Indian Creek water-quality monitoring stations located upstream 

(Station number 03520967) and downstream (Station 

number 03520968) from the Jewell Ridge Lateral natural 

gas pipeline crossing, Tazewell County, Virginia .............................................................8

 5. Water-quality monitors located on the unnamed tributary to 

Indian Creek, Tazewell County, Virginia ............................................................................9

6. Exceedance plots for left-bank and right-bank turbidity collected at the 

upstream Indian Creek water-quality monitor (Station number 03520967) 

Tazewell County, Virginia...........................................................................................................11

7–10. Graphs showing—

 7. Computed unit values of streamflow collected from Indian Creek 

near Cedar Bluff, Virginia (Station number 03520967)...................................................14

 8. Turbidity data collected from Indian Creek, Tazewell County, Virginia, 

at the upstream (Station number 03520967) and downstream 

(Station number 03520968) left-bank water-quality monitors.......................................16

 9. Turbidity data collected from Indian Creek, Tazewell County, Virginia, 

at the upstream (Station number 03520967) and downstream 

(Station number 03520968) right-bank water-quality monitors ....................................17

 10. Turbidity data collected from the unnamed tributary at the 

upstream (Station number 03520980) and downstream (Station 

number 03520981) water-quality monitors, Tazewell County, Virginia........................18

11–13. Exceedance plots for—

 11. Left-bank turbidity collected at the upstream Indian Creek water-quality 

monitor (Station number 03520967) and downstream Indian Creek 

water-quality monitor (Station number 03520968) during the 

pre-construction, construction, and post-construction phases, 

Tazewell County, Virginia....................................................................................................19

 12. Right-bank turbidity collected at the upstream Indian Creek water-quality 

monitor (Station number 03520967) and downstream Indian Creek 

water-quality monitor (Station number 03520968) during the 

pre-construction, construction, and post-construction phases, 

Tazewell County, Virginia....................................................................................................20

 13. Turbidity collected at the upstream unnamed tributary water-quality 

monitor (Station number 03520980) and downstream unnamed tributary 

water-quality monitor (Station number 03520981) during the 

pre-construction, construction, and post-construction phases, 

Tazewell County, Virginia....................................................................................................21
v

14–15. Graphs showing—

 14. Turbidity data collected from the unnamed tributary at the upstream 

(Station number 03520980) and downstream (Station number 03520981) 

water-quality monitors during active pipeline construction 

August 4–7, 2006, Tazewell County, Virginia....................................................................22

 15. Turbidity data collected from the unnamed tributary at the upstream 

(Station number 03520980) and downstream (Station number 03520981) 

water-quality monitors during active pipeline construction 

August 4–8, 2006, Tazewell County, Virginia....................................................................23

16–18. Boxplots showing—

 16. Monthly differences for paired turbidity values collected at the left-bank 

and right-bank upstream Indian Creek water-quality monitors 

(Station number 03520967), Tazewell County, Virginia...................................................24

 17. Monthly differences for paired turbidity values collected at the left-bank 

and right-bank monitors located upstream (Station number 03520967) 

and downstream (Station number 03520968) of the pipeline crossing 

under Indian Creek, Tazewell County, Virginia ...............................................................25

 18. Monthly differences for paired turbidity values collected at the upstream 

(Station number 03520980) and downstream (Station number 03520981) 

unnamed tributary water-quality monitors, Tazewell County, Virginia.......................26

19. Monthly bar plot showing the percentage of turbidity paired differences 

that resulted in a warning for exceeding the turbidity threshold along the 

left bank of Indian Creek, Tazewell County, Virginia.............................................................27

20. Map showing the Indian Creek and unnamed tributary monitoring network 

as well as the ephemeral unnamed tributary, Tazewell County, Virginia..........................29

21. Boxplots of turbidity paired differences for turbidity collected at the left-bank 

and right-bank upstream Indian Creek water-quality monitors (Station 

number 03520967), Tazewell County, Virginia.........................................................................30

Appendixes 1–6. Graphs showing—

 1. Continuous water-quality data collected from Indian Creek, Tazewell County, 

Virginia, at the upstream (Station number 03520967) left-bank water-quality 

monitor: pH, specific conductance, and water temperature......................................37

 2. Continuous water-quality data collected from Indian Creek, Tazewell County,

Virginia, at the upstream (Station number 03520967) right-bank water-quality 

monitor: pH, specific conductance, and water temperature.......................................38

 3. Continuous water-quality data collected from Indian Creek, Tazewell County,

Virginia, at the downstream (Station number 03520968) left-bank water-quality

monitor: pH, specific conductance, and water temperature......................................39

 4. Continuous water-quality data collected from Indian Creek, Tazewell County, 

Virginia, at the downstream (Station number 03520968) right-bank 

water-quality monitor: pH, specific conductance, and water temperature..............40

 5. Continuous water-quality data collected from the unnamed tributary, 

Tazewell County, Virginia, at the upstream (Station number 03520980) 

water-quality monitor: specific conductance and water temperature......................41

 6. Continuous water-quality data collected from the unnamed tributary, 

Tazewell County, Virginia, at the downstream (Station number 03520981) 

water-quality monitor: specific conductance and water temperature......................42
vi

Tables

1. Water-quality monitoring stations, Indian Creek and unnamed tributary, 

Tazewell County, Virginia.............................................................................................................7

2. Statistical summaries of water-quality data collected at Indian Creek 

and unnamed tributary water-quality monitoring stations during 

pre-construction, construction, and post-construction of the 

Jewell Ridge Lateral natural gas pipeline, Tazewell County, Virginia ...............................13

3. Statistical summaries of monthly streamflow conditions in Indian Creek 

near Cedar Bluff, Virginia (USGS station 03520967)..............................................................14

4. Signed-rank test results for turbidity differences from paired upstream 

and downstream turbidity values from Indian Creek and unnamed tributary..................23

Conversion Factors and Vertical Datum

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

square mile (mi2

) 2.590 square kilometer (km2) 

Volume

ounce, fluid (fl. oz) 0.02957 liter (L) 

gallon (gal) 3.785 liter (L) 

gallon (gal) 0.003785 cubic meter (m3

) 

cubic foot (ft3

) 0.02832 cubic meter (m3) 

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

cubic foot per second (ft3

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

Mass

ounce, avoirdupois (oz) 28.35 gram (g) 

pound, avoirdupois (lb) 0.4536 kilogram (kg) 

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

°F=(1.8×°C)+32

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

Specific conductance is reported in microsiemens per centimeter at 25 degrees Celsius (μS/cm 

at 25 °C).

Water year is the 12-month period that extends from October 1 through September 30. The 

water year is designated by the calendar year in which it ends and which includes 9 of the 

12 months. Thus, the year ending September 30, 2008, is called the 2008 water year.
Abstract 

Thousands of miles of natural gas pipelines are installed 

annually in the United States. These pipelines commonly cross 

streams, rivers, and other water bodies during pipeline construction. A major concern associated with pipelines crossing 

water bodies is increased sediment loading and the subsequent 

impact to the ecology of the aquatic system. Several studies have investigated the techniques used to install pipelines 

across surface-water bodies and their effect on downstream 

suspended-sediment concentrations. These studies frequently 

employ the evaluation of suspended-sediment or turbidity data 

that were collected using discrete sample-collection methods. 

No studies, however, have evaluated the utility of continuous 

turbidity monitoring for identifying real-time sediment input 

and providing a robust dataset for the evaluation of long-term 

changes in suspended-sediment concentration as it relates to a 

pipeline crossing.

In 2006, the U.S. Geological Survey, in cooperation with 

East Tennessee Natural Gas and the U.S. Fish and Wildlife 

Service, began a study to monitor the effects of construction 

of the Jewell Ridge Lateral natural gas pipeline on turbidity conditions below pipeline crossings of Indian Creek and 

an unnamed tributary to Indian Creek, in Tazewell County, 

Virginia. The potential for increased sediment loading to 

Indian Creek is of major concern for watershed managers 

because Indian Creek is listed as one of Virginia’s Threatened 

and Endangered Species Waters and contains critical habitat for two freshwater mussel species, purple bean (Villosa 

perpurpurea) and rough rabbitsfoot (Quadrula cylindrical 

strigillata). Additionally, Indian Creek contains the last known 

reproducing population of the tan riffleshell (Epioblasma 

florentina walkeri). Therefore, the objectives of the U.S. 

Geological Survey monitoring effort were to (1) develop a 

continuous turbidity monitoring network that attempted to 

measure real-time changes in suspended sediment (using 

turbidity as a surrogate) downstream from the pipeline crossings, and (2) provide continuous turbidity data that enable the 

development of a real-time turbidity-input warning system and 

assessment of long-term changes in turbidity conditions.

Water-quality conditions were assessed using continuous water-quality monitors deployed upstream and downstream from the pipeline crossings in Indian Creek and the 

unnamed tributary. These paired upstream and downstream 

monitors were outfitted with turbidity, pH (for Indian Creek 

only), specific-conductance, and water-temperature sensors. Water-quality data were collected continuously (every 

15 minutes) during three phases of the pipeline construction: 

pre-construction, during construction, and post-construction. 

Continuous turbidity data were evaluated at various time steps 

to determine whether the construction of the pipeline crossings 

had an effect on downstream suspended-sediment conditions 

in Indian Creek and the unnamed tributary. These continuous turbidity data were analyzed in real time with the aid of a 

turbidity-input warning system. A warning occurred when turbidity values downstream from the pipeline were 6 Formazin 

Nephelometric Units or 15 percent (depending on the observed 

range) greater than turbidity upstream from the pipeline crossing. Statistical analyses also were performed on monthly and 

phase-of-construction turbidity data to determine if the pipeline crossing served as a long-term source of sediment. 

Results of this intensive water-quality monitoring effort 

indicate that values of turbidity in Indian Creek increased 

significantly between the upstream and downstream waterquality monitors during the construction of the Jewell Ridge 

pipeline. The magnitude of the significant turbidity increase, 

however, was small (less than 2 Formazin Nephelometric 

Units). Patterns in the continuous turbidity data indicate that 

the actual pipeline crossing of Indian Creek had little influence 

of downstream water quality; conversely, these data indicate 

upland runoff from the construction right-of-way was the 

primary source of turbidity detected in Indian Creek. Results 

from the analysis of continuous turbidity data collected during the three construction phases from the unnamed tributary 

indicate that the pipeline crossing did not adversely alter longterm water-quality conditions. Turbidity data collected during 

the active construction of the pipeline crossing through the 

unnamed tributary indicate that short-term turbidity increases 

did occur downstream; however, these increases were shown 

to be minimal compared to the turbidity values measured 

during natural runoff events. 

Continuous Turbidity Monitoring in the Indian Creek 

Watershed, Tazewell County, Virginia, 2006–08

By Douglas L. Moyer and Kenneth E. Hyer
2 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

Introduction

Elevated suspended-sediment concentrations are of major 

concern for water-resource managers because of the potential 

adverse impact on living resources and streams, rivers, and 

estuaries (Lloyd and others, 1987; Ryan, 1991; Waters, 1995; 

Wood and Armitage, 1997). Suspended sediments are derived 

from natural processes of upland erosion, lateral movement 

of channels into streambanks, and downcutting of streambeds 

(Waters, 1995). Human activities such as agriculture, logging, mining, and urbanization, however, increase the rate of 

sediment loading to these aquatic systems through accelerated soil and stream-channel erosion (Ryan, 1991; Waters, 

1995). Anthropogenically derived sediment often overwhelms 

the natural assimilative capacity and alters the structure and 

function of the aquatic ecosystem (Cairns, 1977). Elevated 

suspended-sediment concentrations may impair the growth of 

aquatic vegetation by reducing light levels, burying filterfeeding organisms, reducing habitat available for macroinvertebrates, and contributing to decreased fish populations 

(Lenat and others, 1981; Dennison and others, 1993; Box and 

Mossa, 1999; Madsen and others, 2001). An ancillary and 

often overlooked impact of these elevated sediment concentrations is the transport of particle-associated contaminants, such 

as bacteria, nutrients, and metals (Griscom and others, 2000; 

Christensen, 2001). 

Thousands of miles of natural gas pipelines are installed 

annually in the United States (True, 1998; Tobin, 2003). 

Streams, rivers, and other water bodies are routinely crossed 

during pipeline construction. Pipeline construction can lead to 

increased sediment loading to aquatic systems through trench 

excavation and backfilling, erosion and runoff from adjacent 

upland worksites, and discharge of water from hydrostatic 

pipe testing or trench dewatering (Reid and others, 2004). 

Three possible pipeline-crossing techniques are typically 

used when installing pipeline beneath streams, rivers, or other 

water bodies: open-cut wet crossing, open-cut dry crossing, 

and horizontal-directional drilling (HDD) (Zwirn, 2002). 

The open-cut wet crossing approach involves trenching, pipe 

installation, and backfilling in the open stream channel while 

streamflow continues; sediment and pollutant runoff can be 

severe (Zwirn, 2002). The open-cut dry crossing approach 

involves trenching, pipe installation, and backfilling in the 

open stream channel while streamflow is diverted using a 

pump or flume; sediment and pollutant runoff is considerably 

reduced because of the lack of streamflow to transport sediment (Zwirn, 2002). HDD involves drilling a small-diameter 

tunnel at least 5 feet beneath the stream channel and subsequently pulling the preassembled pipeline through the tunnel. 

The HDD method is the least disruptive to the ecological 

integrity of the associated aquatic ecosystem (Zwirn, 2002). 

Several studies have evaluated the impact on the aquatic 

ecosystem associated with various pipeline-crossing techniques. Many of these studies found that the open-cut wet 

crossing method had the greatest impact to the aquatic ecosystem through increased sediment loading downstream from 

the pipeline crossing (Phillip and others, 1981; Young and 

Mackie, 1991; Reid and others, 2004). Reid and others (2002) 

found that the open-cut dry crossing method, using either dam 

and pump or flume crossing, had considerably less downstream transport of sediment compared to the wet-crossing 

method; the greatest impact was observed when the dam/

flume was removed and stored sediment was mobilized. The 

HDD-crossing method has become the preferred method when 

crossing ecologically sensitive streams and rivers because 

of the lack of sediment mobilization; however, this crossing 

method is time-consuming and expensive (Reid and others, 

2002; Lévesque and Dubé, 2007).

In 2005, East Tennessee Natural Gas filed an application 

with the Federal Energy Regulatory Commission (FERC) to 

install the Jewell Ridge Lateral natural gas pipeline in Smyth 

and Tazewell Counties in southwest Virginia. This 32-mile, 

20-inch-diameter pipeline would connect the East Tennessee 

Natural Gas mainline to CNX Gas Company LLC’s existing 

Cardinal States Gathering System (fig. 1). As part of the FERC 

permitting process, a Biological Opinion was prepared by the 

U.S. Fish and Wildlife Service (USFWS) to determine the 

effects of the Jewell Ridge pipeline on federally listed species and federally designated critical habitat (U.S. Fish and 

Wildlife Service, 2006). The USFWS determined that 45 water 

bodies would be crossed by the Jewell Ridge pipeline. Of 

these 45 water bodies, 4 are listed as State-designated Threatened and Endangered Species Waters because of documented 

occurrences of federally and State-listed endangered freshwater mussel species and (or) federally designated critical habitat 

for freshwater mussels. Although the Jewell Ridge pipeline 

will cross three other Threatened and Endangered Species 

Waters, Indian Creek was selected by the USFWS for intensive monitoring as a tool to help protect the critically endangered mussels or their required habitat. The USFWS requested 

that intensive turbidity and macroinvertebrate monitoring be 

performed prior to, during, and after pipeline crossing. 

The USFWS was concerned about the Jewell Ridge pipeline construction because Indian Creek is listed as one of the 

Virginia Department of Game and Inland Fisheries’ designated 

Threatened and Endangered Species Waters and contains 

federally designated critical habitat for two endangered freshwater mussel species, purple bean (Villosa perpurpurea) and 

rough rabbitsfoot (Quadrula cylindrical strigillata), and the 

last known reproducing population of the tan riffleshell (Epioblasma florentina walkeri). The purple bean, rough rabbitsfoot, 

and tan riffleshell are filter-feeding mussels that feed on algae 

and other microorganisms suspended in the water column. 

These mussels require relatively silt-free substrate for survival. 

The USFWS in accordance with Section 7 of the Endangered Species Act (ESA) of 1973 (87 Stat. 884, as amended; 

16 U.S.C. 1531 et seq.) requested “sound and reasonable 

monitoring” to document potential water-quality impacts. 

The primary impact of concern is that instream suspendedsediment concentrations, due to pipeline-related construction 

activities, could be detrimental to the quality of the habitat 

required by these threatened and endangered species. 
Introduction 3

Figure 1. The Jewell Ridge Lateral natural gas pipeline, Virginia.

82° 81°30'

37°30'

37°

Jewell Ridge Pipeline

Indian Creek Watershed

WEST VIRGINIA

NORTH CAROLINA

KENTUCKY

Tazewell

Smyth

81

0 10 20 MILES

0 10 20 KILOMETERS
4 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

In 2006, the U.S. Geological Survey (USGS), in cooperation with East Tennessee Natural Gas and the U.S. Fish 

and Wildlife Service, began a study to monitor water-quality 

conditions in Indian Creek and an unnamed tributary to 

Indian Creek. Turbidity, a well-documented surrogate for fine 

suspended sediment (Christensen, 2001), was the primary 

water-quality property to be monitored prior to, during, and 

after construction of the pipeline crossing of Indian Creek and 

the unnamed tributary to Indian Creek. The primary objective 

of the USGS monitoring effort was to identify whether the construction of the Indian Creek pipeline crossing would adversely

impact the suspended-sediment concentrations in Indian Creek. 

The specific study objectives were to (1) develop a continuous turbidity monitoring network that attempted to measure 

real-time changes in suspended-sediment conditions (using 

turbidity as a surrogate) downstream from the pipeline crossing

in Indian Creek and the unnamed tributary to Indian Creek, and 

(2) provide continuous turbidity data that allow for the development of a turbidity-input warning system and assessment of 

long-term changes in turbidity conditions.

Purpose and Scope

This report describes monitored turbidity conditions in 

Indian Creek and an unnamed tributary to Indian Creek prior 

to, during, and after construction of the Jewell Ridge Lateral 

natural gas pipeline crossing. Turbidity values were collected 

every 15 minutes upstream and downstream from the pipeline crossing in Indian Creek and an unnamed tributary to 

Indian Creek from April 2006 to April 2008. This report also 

describes the methods of collection and the results of using 

these continuous turbidity data as a near real-time and longterm indicator of elevated suspended sediment downstream 

from the pipeline crossings. This information will provide 

East Tennessee Natural Gas and USFWS with information on 

the influence of the Jewell Ridge Lateral natural gas pipeline 

crossings on instream turbidity conditions.

Description of Study Area

The Indian Creek watershed is located in Tazewell 

County, in southwest Virginia (fig. 1). The headwaters of 

Indian Creek originate in the primarily forested northernmost 

part of Tazewell County. Indian Creek flows to the southwest, 

where it joins the Clinch River near Cedar Bluff, Virginia 

(fig. 2). The Clinch River, which is known for its biodiversity and large number of imperiled species, flows southwest 

where it joins the Tennessee River and ultimately, the Mississippi River. Indian Creek has a drainage area of 33.9 square 

miles and is composed of forest (78.5 percent), agricultural 

(13.9 percent), and residential (7.6 percent) land use.

Indian Creek lies within the Appalachian Plateaus 

Physiographic Province, which is a narrow chain of westwardfacing folded mountains that extend from southwestern Virginia to central New York (Fenneman, 1938). The Appalachian 

Plateaus consist of the Allegheny Plateau and the Cumberland 

Plateau. The Cumberland Plateau is the dominant physiographic feature in the Indian Creek watershed. The underlying 

geology in the Appalachian Plateaus is dominated by shale, 

sandstone, and coal (Fenneman, 1938). Extensive erosion has 

resulted in topography consisting of steep slopes and narrow 

ridges and valleys (Hayes, 1991; Woods and others, 1999). 

Jewell Ridge Pipeline Construction

The Jewell Ridge pipeline was brought into the Indian 

Creek watershed by employing overland- and stream-channel 

crossing methods in accordance with Federal regulations 

and guidelines. The overland pipeline construction required 

the creation of a 100-foot-wide construction right-of-way 

(ROW). The ROW measured 65 feet on the working side and 

35 feet on the spoil side. The overland-pipeline construction 

method involved installing the pipeline as a moving assembly 

line with activities that proceeded in the following sequence: 

surveying and flagging of the ROW, clearing and grading, trenching, stringing and bending, welding, lowering-in, 

backfilling, hydrostatic testing, cleanup and restoration, and 

post-construction monitoring. Erosion- and sediment-control 

measures were employed along the entire length of the ROW. 

Two stream-channel crossing techniques were utilized in 

the Indian Creek watershed. Indian Creek was crossed using 

HDD. This method allows for the installation of pipelines 

beneath roadways, railroads, and streams to minimize the 

potential impact of elevated sediment loading to the threatened and endangered mussel species and their associated 

habitat. The HDD method allowed for the installation of the 

pipeline more than 5 feet below the channel bottom of Indian 

Creek. The Indian Creek pipeline crossing is approximately 

1.6 miles east-northeast of Cedar Bluff, Virginia, and is 

approximately 1,100 feet upstream from Route 631 (fig. 2). 

The borehole under Indian Creek was continually dewatered 

during the boring process. The water and associated constituents were captured and stored in settling tanks on site. Once 

the particles settled from suspension, the captured water was 

returned to Indian Creek. Impacts to vegetative cover on both 

streambanks were minimized by leaving a 50-foot buffer 

on the south bank and a 35-foot buffer on the north bank of 

undisturbed vegetation.

The pipeline route also crossed an unnamed tributary 

(fig. 2), which flows into Indian Creek downstream from the 

Route 631 bridge, but still upstream from several of the critical mussel populations residing on the main stem of Indian 

Creek. The open-cut dam and flume dry-crossing method 

was used to install the pipeline across the unnamed tributary 

because no critical mussel habitat exists at or immediately 

downstream from the unnamed tributary crossing. This technique isolates flow from the construction area while the pipeline is installed in the dry channel. The dry channel is trenched 

so that the pipeline is installed at a minimum of 5 feet beneath 

the active channel.
Introduction 5

Figure 2. The Indian Creek watershed, Tazewell County, Virginia.

0

0

1 2 3 4 MILES

1 2 3 4 KILOMETERS











Bandy

Harman

Busthead

Van Dyke

Cedar Bluff

Clinch River

Unnamed

Tributary

Indian Creek

81°46' 81°44' 81°42' 81°40' 81°38'

37°14'

37°12'

37°10'

37°8'

37°6'

WEST VIRGINIA

631

Jewell Ridge Pipeline
6 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

Methods of Investigation

In most streams, suspended sediments are generally transported during stormflow periods (Wolman and Miller, 1960), 

while rainfall-induced surface-runoff processes are active; 

however, during these runoff periods, the fewest suspendedsediment data are generally collected. One promising new 

technology for improved suspended-sediment determination 

involves the continuous monitoring of turbidity, using an 

in-situ sensor, as a surrogate for suspended-sediment concentrations. Turbidity measurements are usually well correlated 

to suspended-sediment concentrations; because turbidity 

represents an optical measure of water clarity, the presence 

of suspended sediment directly influences this measurement 

of clarity. Using turbidity values as a surrogate for suspendedsediment concentration is not new, but until recently, technological limitations have made this approach largely unusable. Walling (1977) described this surrogate approach using turbidity. 

The development of continuous turbidity records has gradually 

become more feasible because of technical improvements to 

in-situ water-quality sensors and improved telecommunications equipment. Continuous turbidity measurement has now 

become a more common field approach because it provides 

substantially more detailed and more accurate information on 

suspended-sediment concentrations than previously possible.

Continuous Water-Quality Monitor Installation

The continuous water-quality monitoring network was 

designed to detect sediment inputs, as indicated by turbidity, 

directly associated with the construction and pipeline crossing activities on Indian Creek and the unnamed tributary 

while also minimizing the chance of detecting sediment inputs 

unrelated to the pipeline construction. Therefore, a paired 

upstream-downstream design was implemented around the 

Indian Creek and unnamed tributary pipeline crossings (fig. 3). 

Figure 3. The Indian Creek and unnamed tributary monitoring network, Tazewell County, Virginia.

Busthead

Van Dyke

Cedar Bluff

03520968

03520981

03520967

03520980

Unnamed Tributary

Indian Creek

81°45'40" 81°44'40" 81°43'40" 81°42'40" 81°41'39"

37°7'57"

37°6'57"

37°5'56"

37°4'56"

EXPLANATION

MONITORING STATION

Jewell Ridge Pipeline

631

0

0

1 2 MILES

1 2 KILOMETERS
Methods of Investigation 7

An additional water-quality-monitoring concern in Indian 

Creek was incomplete water-column mixing in the monitoring 

reach. To address this concern, two additional monitors were 

added so that the paired upstream and downstream monitors 

consisted of a near left-bank and near right-bank design. The 

use of dual upstream monitors located off each bank of the 

stream is appropriate for two reasons. First, the use of monitors located only a short distance off the streambank provided 

a dataset that was directly comparable to the dataset from the 

downstream monitors and used to determine how conditions 

change within the monitoring reach. Secondly, an ephemeral 

unnamed tributary to Indian Creek is located approximately 

350 feet above the pipeline crossing; the potential sediment 

contributions from this unnamed tributary needed to be 

documented to ensure that the potential sediment contributions were not erroneously interpreted as sediment inputs from 

the pipeline crossing. The monitoring stations on both Indian 

Creek and the unnamed tributary were instrumented and 

activated 1 month prior to the initiation of the Jewell Ridge 

pipeline construction within the Indian Creek watershed. The 

monitoring allowed for the establishment of a brief baseline 

understanding of the differences in turbidity levels upstream 

and downstream from the pipeline crossings. 

Indian Creek Network

The effect of the Indian Creek pipeline crossing on 

water-quality conditions was monitored by four continuous water-quality monitors installed pair-wise upstream and 

downstream from the pipeline crossing. Two monitors were 

installed 120 feet upstream (USGS station 03520967) from 

the pipeline crossing (fig. 3). These two upstream monitors 

were suspended from a boom so that one monitor was submersed 10 feet from the left bank and the second monitor was 

submersed 10 feet from the right bank (fig. 4A, table 1). The 

remaining two monitors were suspended from a boom 200 feet 

downstream (USGS station 03520968) from the pipeline 

crossing so that one monitor was submersed 10 feet from the 

left bank and the second monitor was submersed 10 feet from 

the right bank (fig. 4B, table 1). Each Indian Creek monitoring station was instrumented with a YSI Inc. Model 6920 

multi-parameter sonde, which was outfitted with turbidity, 

pH, specific-conductance, and water-temperature sensors, and 

values for each of these water-quality properties were collected every 15 minutes. The water-quality values were stored 

and subsequently transmitted hourly using a Sutron SatLink2 

GOES Satellite Transmitter and Logger. The hourly transmitted data were stored in and subsequently made publicly 

available via the USGS National Water Information System 

(NWIS) at http://waterdata.usgs.gov/va/nwis. 

Unnamed Tributary Network

The effect of the unnamed tributary pipeline crossing 

on water-quality conditions was monitored by two continuous water-quality monitors installed upstream (USGS station 03520980) and downstream (USGS station 03520981) 

from the crossing (fig. 3). The upstream monitor was located 

approximately 100 feet above the pipeline crossing whereas the 

downstream monitor was located approximately 65 feet below 

the pipeline crossing (fig. 5, table 1). Each monitoring station 

was instrumented with a YSI Inc. Model 600 multi-parameter 

sonde. The YSI Inc. Model 600 multi-parameter sonde, which 

has a smaller diameter than the Model 6920 multi-parameter 

sonde, was selected for the unnamed tributary because of 

the shallow surface-water depths encountered. Each sonde 

was outfitted with turbidity, specific-conductance, watertemperature, and water-level sensors. Values for each of these 

constituents were collected every 15 minutes and then stored 

and subsequently transmitted hourly using a Sutron SatLink2 

GOES Satellite Transmitter and Logger. These hourly transmitted data were stored in and subsequently made publicly 

available via NWIS at http://waterdata.usgs.gov/va/nwis.

Table 1. Water-quality monitoring stations, Indian Creek and unnamed tributary, Tazewell County, Virginia.

Station 

number Station name LatitudeLongitude

Left- and right-bank 

water-quality 

monitors deployed

03520967 Indian Creek near Cedar Bluff, Va. 37°05'47"

81°44'27"

Yes

03520968 Indian Creek above Rt. 631 near Cedar Bluff, Va. 37°05'42"

81°44'28"

Yes

03520980 Indian Creek Tributary along Rt. 631 near Cedar Bluff, Va. 37°05'35"

81°44'13"

No

03520981 Indian Creek Tributary above mouth nr Cedar Bluff, Va. 37°05'32"

81°44'19"

No
8 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

Figure 4. Indian Creek water-quality monitoring stations located (A) upstream (Station number 03520967) 

and (B) downstream (Station number 03520968) from the Jewell Ridge Lateral natural gas pipeline 

crossing, Tazewell County, Virginia.

(A)

(B)
Methods of Investigation 9

Figure 5. Water-quality monitors located on the unnamed tributary to Indian Creek, Tazewell 

County, Virginia. The monitoring station located in the foreground is the downstream monitor 

(Station number 03520980). The monitoring station in the background is the upstream monitor 

(Station number 03520981). 
10 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

Continuous Water-Quality Monitor Maintenance

Approximately every 4 weeks, the water-quality monitors 

were serviced in the field to clean the equipment, evaluate the 

quality of the data being collected, and recalibrate the instrument (if necessary). This monitor servicing was performed 

using the methods described in the USGS guidelines for the 

operation and maintenance of continuous monitors (Wagner 

and others, 2000). A summary of the maintenance steps is 

presented here. In all cases, water-quality properties were 

measured before and after the instrument was cleaned of any 

algae or biofilm that may have developed. The differences 

before and after cleaning were used to evaluate whether the 

data needed to be corrected for instrument fouling. Following 

the fouling check, the calibration for pH, specific conductance, 

and turbidity were all checked using known standards. Discrepancies between the known values of the standards and the 

readings from the individual sondes were used to determine 

whether the data needed to be corrected for a drift in instrument calibration. Following the fouling and calibration checks, 

the instrument was re-calibrated if any of the measured waterquality properties were out of instrument tolerance (Wagner 

and others, 2000). Upon returning to the office from the 

field-maintenance visit, any necessary data corrections were 

applied to the data record and the data on the NWIS Web site 

were updated.

In addition to the monthly monitor maintenance, the 

entire water-quality record for each measured water-quality 

property was reviewed and finalized at the end of each water 

year. This annual review evaluated all the fouling and calibration drift checks, and screened the data for anomalous values, 

before the quality of the record was rated (either as excellent, 

good, fair, or poor). These ratings were determined on the 

basis of the corrections that had been applied to the record, 

and the criteria used for the ratings were those provided by 

Wagner and others (2000). 

Continuous Stream Gage Operation

A standard USGS stream gage was installed, following 

established USGS procedures (Buchanan and Somers, 1968), 

at the upstream Indian Creek monitoring site (USGS station 

03520967) (fig. 3) in October 2006 and maintained through 

April 2008 (table 1). Indian Creek water levels were measured 

at 15-minute intervals using a Keller-Pressure Systems, Incorporated (KPSI) pressure transducer. These water-level (stage) 

data were stored and subsequently transmitted hourly using a 

Sutron SatLink2 GOES Satellite Transmitter and Logger. The 

hourly transmitted data were stored in and subsequently made 

publicly available via NWIS at http://waterdata.usgs.gov/

va/nwis. Stream discharge was measured routinely, during a 

variety of streamflow conditions, to establish a stage-discharge 

rating for Indian Creek. This stage-discharge rating was used 

to calculate stream discharge for each 15-minute interval of 

measured stage.

Data Analysis

The primary objective of the USGS monitoring effort 

was to identify whether the construction of the pipeline crossings would adversely impact the sediment-water quality in 

Indian Creek and the unnamed tributary. The specific study 

objectives were to (1) develop a continuous turbidity monitoring network that attempted to measure real-time changes in 

suspended-sediment conditions (using turbidity as a surrogate) downstream from the pipeline crossing in Indian Creek 

and the unnamed tributary to Indian Creek, and (2) provide 

continuous turbidity data that allow for the development of 

a turbidity-input warning system and assessment of longterm changes in turbidity conditions. The following sections 

document the approach that was used to monitor and evaluate 

water-quality conditions.

Continuous Water-Quality Data Collection

Turbidity, water temperature, specific conductance, and 

pH measurements were collected at the four water-quality 

monitoring stations on Indian Creek, and turbidity, water 

temperature, specific conductance, and water levels were 

collected at the two water-quality monitoring stations on 

the unnamed tributary. The primary objective for collecting 

these water-quality data was to enable East Tennessee Natural 

Gas, the USFWS, and the USGS to detect changes in waterquality conditions, more specifically sediment-water quality, 

immediately downstream from the pipeline crossings. These 

water-quality properties were collected during three phases of 

the pipeline construction: pre-construction, during construction, and post-construction. The time periods for these three 

phases were:

1. Pre-construction—April 28, 2006, through May 31, 2006;

2. Construction—June 1, 2006, through August 31, 2006; and

3. Post-construction—September 1, 2006, through 

April 9, 2008.

These data were essential for determining whether the construction of the Jewell Ridge pipeline crossing altered the 

short-term and long-term water quality in Indian Creek and the 

unnamed tributary. 

Assessment of Long-Term Turbidity Patterns

The objective of the long-term water-quality assessment 

was to determine the influence of the pipeline crossing on 

downstream suspended-sediment conditions (using turbidity 

as a surrogate for suspended sediment) in Indian Creek and the 

unnamed tributary. Statistical analysis of the paired differences of the continuously collected upstream and downstream 

turbidity data is the most direct approach to determine whether 

turbidity conditions are changing downstream from the pipeline crossing. A signed-rank test (Helsel and Hirsch, 1992) 

was selected to test the null hypothesis for Indian Creek and 
Methods of Investigation 11

the unnamed tributary. The signed-rank test was performed 

on the paired differences obtained from the following Indian 

Creek paired monitors: upstream minus downstream left bank 

(USLB and DSLB, respectively); upstream minus downstream 

right bank (USRB and DSRB, respectively); and upstream 

minus downstream monitors in the unnamed tributary (USTR 

and DSTR, respectively). The null hypothesis associated with 

an analysis of paired differences is that the median paired 

difference is equal to zero. This null hypothesis is true when 

the number of positive paired differences (upstream turbidity 

is greater than downstream turbidity) is approximately equal 

to the negative paired differences (upstream turbidity is less 

than downstream turbidity). The alternative hypothesis is that 

the median paired difference value is not equal to zero. A test 

was considered statistically different if the p-value was less 

than 0.05. These paired differences were calculated for each 

of the three time periods (pre-construction, construction, and 

post-construction). 

In addition to the statistical analysis of paired differences, 

graphical presentations of turbidity data were used to visually determine differences between upstream and downstream 

values of turbidity. Monthly boxplots of paired differences, 

obtained from the upstream, right-bank, and left-bank monitors 

on Indian Creek and the upstream and downstream monitors on 

the unnamed tributary, were used to determine if the variability 

within the monthly paired differences was associated with the 

phase of pipeline construction. Each boxplot shows the distribution of the monthly paired differences by identifying the 10th, 

25th, 50th, 75th, and 90th percentiles, where each percentile 

represents the percentage of samples that reside below that 

designated value. If the median (50th percentile) turbidity 

paired difference is 1.0 Formazin Nephelometric Units (FNU), 

for example, then 50 percent of monthly paired differences 

are greater than 1.0 FNU and 50 percent of the monthly paired 

differences are less than 1.0 FNU. Exceedance plots also were 

used to identify differences in turbidity conditions upstream 

and downstream from the pipeline crossing. Exceedance plots 

are similar to boxplots because they are used to relate a given 

turbidity value to the frequency of occurrence. The shape of 

the exceedance plot, however, can assist in identifying processes that may be controlling turbidity in Indian Creek and 

the unnamed tributary. For example, exceedance plots for the 

pre-construction turbidity values collected at the USLB (red 

line) and the USRB (blue line) monitor are shown in figure 6. 

These plots show that the USLB and USRB turbidity values 

have similar distributions with similar medians (50th percentile) 

of 3.0 and 3.2 FNU, respectively. The black line represents a 

hypothetical condition obtained by doubling all turbidity values 

collected at the USRB monitor, which shows that increases in 

turbidity cause the exceedance plot to shift to the right. 

Figure 6. Exceedance plots for left-bank and right-bank turbidity collected at the upstream Indian Creek 

water-quality monitor (Station number 03520967) Tazewell County, Virginia. The black line represents the rightbank turbidity values multiplied by 2.

PERCENT OF TIME TURBIDITY IS EQUALED OR EXCEEDED

100

90

80

70

60

50

40

30

20

10

0

0.1 1 10 100 1,000

TURBIDITY, IN FORMAZIN NEPHELOMETRIC UNITS

Right-bank turbidity

2 × (Right-bank turbidity)

Left-bank turbidity
12 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

Turbidity-Input Warning System

The ability to detect real-time sediment input (using turbidity as a surrogate) downstream from the Indian Creek and 

unnamed tributary pipeline crossings was a primary requirement of the USFWS Biological Opinion (U.S. Fish and Wildlife Service, 2006). East Tennessee Natural Gas developed a 

real-time turbidity-input warning system in order to ensure 

that the water-quality requirement established by the USFWS 

was met. The thresholds for detecting changes in turbidity 

downstream from the pipeline crossing were:

1. For turbidity values less than 40 FNU, a 6-FNU increase in 

turbidity detected downstream from the pipeline crossing, 

relative to the associated turbidity value upstream from the 

pipeline crossing, sustained for no less than 1 hour, or

2. For turbidity values greater than or equal to 40 FNU, a 

15-percent increase in turbidity detected downstream from 

the pipeline crossing, relative to the associated turbidity 

value upstream from the pipeline crossing, sustained for no 

less than 1 hour.

The real-time turbidity-input warning system used continuous 

turbidity data collected by the USGS at the paired upstream 

and downstream monitors on Indian Creek and the unnamed 

tributary. Turbidity data were collected every 15 minutes 

and transmitted hourly to the USGS NWIS Web site. East 

Tennessee Natural Gas automatically retrieved these turbidity data and compared them to the established thresholds. 

If a threshold was violated for four consecutive turbidity 

observations (1 hour), then the on-site manager, overseeing 

the pipeline construction, received a warning that a potential 

sediment input was detected downstream from the pipeline 

crossing. The on-site manager was required to (1) investigate the cause of the threshold exceedence, (2) document 

whether instream turbidity (sediment derived from the 

pipeline crossing construction) was the cause of the threshold 

exceedence, and (3) cease construction activities until the 

sediment input was corrected. This warning system also was 

subject to false-positive warnings. A false-positive warning 

is one that is not caused by sediment input from the pipeline 

crossing but is caused by a variety of sources that include: 

instream debris such as leaves and trash that get caught on the 

downstream turbidity probe; bio-fouling on the downstream 

turbidity probe; or mechanical malfunction of the downstream 

turbidity probe. 

Water-Quality Patterns in Indian Creek 

and the Unnamed Tributary 

Water-quality data collected during pre-construction, 

construction, and post-construction phases of the pipeline 

crossings beneath Indian Creek and through an unnamed tributary are summarized in table 2. Water-quality data include the 

median and the range (minimum and maximum) for turbidity, 

pH, specific conductance, and water temperature collected 

during the three phases of construction. Median values of 

pH ranged from 8.0 to 9.4 during the duration of the study. 

The highest median pH values occurred during the construction phase at both the Indian Creek left-bank and right-bank 

downstream monitors 9.4 and 8.4, respectively. Median values 

of specific conductance observed in Indian Creek ranged from 

198 to 244 microsiemens per centimeter (μS/cm) whereas 

median values of specific conductance observed in the 

unnamed tributary ranged from 394 to 499 μS/cm. Specificconductance values in the unnamed tributary were typically 

double the values observed in Indian Creek. Water temperature 

was similar in Indian Creek and the unnamed tributary and 

reflected the phase of construction during which temperature 

was measured. The highest water-temperature values were 

observed during the construction period, for example, which 

took place during the summer months. Time-series plots for 

pH, specific conductance, and water temperature collected 

from Indian Creek and specific conductance and water temperature collected from the unnamed tributary are provided for 

each monitoring station in Appendixes 1 through 6.

Indian Creek Streamflow

Continuous streamflow data were collected from Indian 

Creek at the upstream monitoring station (USGS station 

03520967) from October 2006 through April 2008 (fig. 7). 

Given the October 2006 start date, streamflow data were only 

available during the post-construction phase of the study. 

Monthly summary statistics for streamflow conditions in 

Indian Creek, which include the minimum, 25th percentile, 

median, 75th percentile, and maximum, are presented in 

table 3. Monthly median values of streamflow in Indian Creek 

ranged from 0.39 to 61.66 cubic feet per second (ft3/s) in October 2007 and April 2008, respectively. The extensive drought 

that affected much of southeastern and mid-Atlantic United 

States is evident in the Indian Creek streamflow data, with 

diminished values of streamflow measured from July 2007 

through January 2008. 
Methods of Investigation 13

Table 2. Statistical summaries of water-quality data collected at Indian Creek and unnamed tributary water-quality monitoring stations 

during pre-construction, construction, and post-construction of the Jewell Ridge Lateral natural gas pipeline, Tazewell County, Virginia.

[Values presented are the median and range (minimum and maximum) for each construction period; FNU, Formazin Nephelometric Units; μS/cm at 25 oC, 

microsiemens per centimeter at 25 degrees Celsius; oC, degrees Celsius; US, upstream; DS, downstream; —, no data] 

Turbidity,

FNU

pH,

standard units

Specific conductance,

μS/cm at 25 oC

Water temperature,

oC

Indian Creek, Pre-Construction

US left bank 3.2

(1.6– 94)

8.1

(7.8 –9.1)

198

(146 –231)

13.9

(9.8 – 24.1)

US right bank 3.0

(1.4– 89)

8.1

(7.8 –9.0)

202

(146 –236)

13.0

(9.9 – 23.0)

DS left bank 3.4

(0.9 – 94)

8.2

(7.9 – 9.2)

199

(144 – 240)

13.9

(9.8 – 24.0)

DS right bank 3.6

(1.8–86)

8.1

(7.7–9.0)

200

(146 – 233)

13.0

(9.8 – 23.0)

Unnamed Tributary, Pre-Construction Period

US 13.0

(0.1 – 1,060)

— 394

(229 – 475)

13.1

(9.0 – 24.1)

DS 14.0

(3.4 – 1,130)

— 401

(250 –467)

13.2

(9.0 –25.0)

Indian Creek, Construction Period

US left bank 4.0

(1.8 – 540)

8.1

(7.7 –8.8)

228

(93 –335)

20.0

(13.8 –26.2)

US right bank 3.9

(1.4 – 440)

8.1

(7.6 –8.7)

231

(77 –331)

20.8

(13.0 –25.0)

DS left bank 5.5

(1.8 – 300)

9.4

(7.9 –10.2)

228

(83 –333)

20.7

(13.8 –26.0)

DS right bank 4.5

(1.3–290)

8.4

(7.8 – 9.1)

231

(80 –336)

20.0

(13.0 –26.2)

Unnamed Tributary, Construction Period

US 11.0

(4.0–1,250)

— 499

(161 –556)

19.2

(12.2 –26.2)

DS 8.3

(1.5–1,290)

— 487

(178 – 537)

19.4

(12.3 –26.6)

Indian Creek, Post-Construction Period

US left bank 2.7

(0.0–970)

8.0

(6.8 –9.3)

240

(26 –441)

10.5

(0.1 –26.3)

US right bank 2.6

(0.1 – 1030)

8.1

(6.6 –9.5)

239

(84 –437)

10.5

(0.2 –26.1)

DS left bank 2.5

(0.0 –740)

8.1

(6.2 –10.6)

239

(83 –445)

10.5

(0.1 –27.2)

DS right bank 2.7

(0.1 –720)

8.1

(7.3 –9.4)

244

(54 –439)

10.4

(0.1 –27.2)

Unnamed Tributary, Post-Construction Period

US 10.0

(0.4 – 2,340)

— 472

(188 –905)

10.5

(0.1 –25.6)

DS 9.9

(0.4 – 1,780)

— 471

(188 –862)

10.5

(0.1 –26.4)
14 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

Figure 7. Computed unit values (15-minute) of streamflow collected from Indian Creek near Cedar Bluff, 

Virginia (Station number 03520967).

0

100

200

300

400

500

600

700

800

900

 Apr

2006

 Aug

2006

 Dec

2006

 Apr

2007

 Aug

2007

 Dec

2007

 Apr

2008

STREAMFLOW, IN CUBIC FEET PER SECOND

Table 3. Statistical summaries of monthly streamflow conditions in Indian Creek near Cedar Bluff, Virginia (Station number 03520967). 

[Streamflow is in cubic feet per second]

Date

(month/year) Minimum 25th Percentile Median 75th Percentile Maximum

10/2006 7.25 10.00 18.38 32.53 213.10

11/2006 4.73 22.33 39.90 53.81 116.82

12/2006 3.70 10.00 11.81 14.34 22.33

1/2007 13.29 23.75 29.97 42.69 96.23

2/2007 5.01 11.34 14.34 29.97 137.86

3/2007 16.57 22.33 29.97 53.81 595.51

4/2007 14.88 25.23 37.08 66.42 711.91

5/2007 5.60 9.57 17.16 39.00 158.90

6/2007 2.80 3.95 4.73 7.25 22.33

7/2007 2.80 3.01 3.70 5.91 34.31

8/2007 2.80 3.01 3.23 3.46 6.23

9/2007 2.80 3.46 3.95 4.46 11.81

10/2007 0.23 0.33 0.39 0.64 4.96

11/2007 0.53 0.97 1.32 1.90 6.84

12/2007 1.20 1.90 4.96 7.55 25.17

1/2008 3.00 6.17 7.92 11.27 720.34

2/2008 7.55 12.71 14.26 28.29 66.42

3/2008 17.69 28.29 39.00 59.36 867.04

4/2008 14.26 17.69 61.66 102.32 561.61
Water-Quality Patterns in Indian Creek and the Unnamed Tributary 15

Instream Turbidity Conditions

Turbidity was the primary water-quality property used to 

determine if instream water-quality conditions were altered as 

a result of the Jewell Ridge pipeline crossing beneath Indian 

Creek and through the unnamed tributary. Turbidity data were 

collected from each of the six water-quality monitors deployed 

in Indian Creek and the unnamed tributary and were used to 

evaluate instream water-quality conditions at various time 

spans that included: (1) full period of record; (2) the three 

phases of construction; (3) monthly; and (4) hourly. Results 

from all time spans were used to formulate a conceptual model 

for turbidity patterns observed in Indian Creek. 

Turbidity values collected during the nearly 24-month 

period from Indian Creek showed four periods of elevated turbidity: June 2006 through July 2006; September 2006 through 

November 2006; April 2007 through July 2007; and February 2008 through March 2008 (figs. 8 and 9). These elevated 

turbidity periods were primarily related to periods of wet 

weather and increased streamflow, and are fairly consistent 

between the paired upstream and downstream monitors as well 

as the left-bank and right-bank monitors. The elevated turbidity observed during March and April 2007, for example, corresponded with the increased streamflow that was measured in 

Indian Creek during this same period (fig. 7). 

Patterns of turbidity measured in the unnamed tributary 

were much more variable during the 24-month monitoring period (fig. 10), compared with the patterns of turbidity 

measured in Indian Creek. Turbidity values, measured in 

the unnamed tributary, were routinely at 1,000 FNU at both 

the upstream and downstream monitors (fig. 10). Turbidity 

values measured in the unnamed tributary were two to four 

times greater than turbidity values measured in Indian Creek 

(table 2). Turbidity in the unnamed tributary seems to be influenced by other watershed factors, in addition to streamflow, 

which may potentially include unregulated discharges from 

local residential and commercial properties as well as the local 

community working in and around this tributary.

Long-Term Patterns of Turbidity in Indian Creek 

and the Unnamed Tributary

Exeedance plots were used to graphically compare 

the turbidity values measured during the pre-construction, 

construction, and post-construction phases of the pipeline 

crossing beneath Indian Creek and through the unnamed 

tributary. Exceedance plots show integrated turbidity data, 

collected during each phase of construction, as a function of 

the frequency of occurrence. Indian Creek turbidity values, 

collected during the three phases of construction, are shown 

in figures 11 and 12. The initial turbidity patterns from both 

the left- and right-bank monitors that can be identified from 

these exceedance plots show that turbidity measured during 

the construction phase was greater (shifted to the right on the 

exceedance plot), than turbidity measured during the pre- and 

post-construction phases. This pattern of elevated turbidity 

during the construction phase was consistent at the upstream 

and downstream monitors; however, the range of turbidity 

values between the three construction phases was greatest 

at the downstream monitors (figs. 11 and 12, table 2). These 

patterns indicate that there was likely a suspended-sediment 

input (using turbidity as a surrogate) to Indian Creek between 

the upstream and downstream monitors during the construction period, however, the magnitude of the sediment input 

between these monitors is relatively small. The observed range 

in median values, for example, for the three pipeline construction phases at the upstream monitors was 1.3 FNU for each. 

The range in median values for the construction phases at 

the downstream monitors increased to 3.0 and 1.8 FNU for 

the left- and right-bank monitors, respectively. The range in 

median turbidity values, between the three phases of construction, would be identical for the upstream and downstream 

monitors if a source of turbidity was not present between the 

two locations. The input of turbidity, during the active construction phase, is more pronounced at the downstream leftbank monitor compared to the downstream right-bank monitor. 

The source of the turbidity input between the upstream and 

downstream monitoring sites during the construction period 

may be related to the pipeline crossing activities, but other 

potential turbidity sources between the two monitors such as 

bank erosion, upstream sediment sources, algal growth, and 

point inputs from adjoining residential properties cannot be 

excluded. The discrepancy between the downstream left- and 

right-bank monitors is discussed further in the “Conceptual Model for Indian Creek Turbidity Patterns” section of 

this report. 

The exceedance plots for turbidity values collected 

upstream and downstream from the pipeline crossing in the 

unnamed tributary (fig. 13) exhibit a considerably different pattern than the one observed in Indian Creek (figs. 11 

and 12). The major difference is that turbidity values measured 

during the construction period were generally less than those 

measured during the pre- and post-construction phases. This 

pattern also was consistent at both the upstream and downstream monitors. The decrease in turbidity during the construction phase may be related to the diversion of streamflow 

away from the trenching activity within the active channel. 

As with Indian Creek, the range of turbidity values between 

the three construction phases was greatest at the downstream 

monitors; however, this increased range was directly related 

to discrepancies between turbidity values at the upstream and 

downstream monitors collected during the pre-construction 

phase, not the construction phase. The observed range in 

median values for the construction phases at the upstream 

monitor was 3.0 FNU; the range in median values for the 

construction phases at the downstream monitor was 5.7 FNU 

(fig. 13, table 2). 

The exceedance plots of turbidity data from the unnamed 

tributary, overall, show that the pipeline crossing was not a 

substantial source of suspended sediment (using turbidity as a 

surrogate). A closer look at the turbidity data collected during 
16 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08 TURBIDITY, IN FORMAZIN NEPHELOMETRIC UNITS

0

100

200

300

400

500

600

700

800

900

1,000

0

100

200

300

400

500

600

700

800

900

1,000

TURBIDITY, IN FORMAZIN NEPHELOMETRIC UNITS

 Apr

2006

 Aug

2006

 Dec

2006

 Apr

2007

 Aug

2007

 Dec

2007

 Apr

2008

(B)

(A)

Figure 8. Turbidity data (15-minute interval) collected from Indian Creek, Tazewell County, Virginia, at the 

(A) upstream (Station number 03520967) and (B) downstream (Station number 03520968) left-bank 

water-quality monitors.
Water-Quality Patterns in Indian Creek and the Unnamed Tributary 17

Figure 9. Turbidity data (15-minute interval) collected from Indian Creek, Tazewell County, Virginia, at the 

(A) upstream (Station number 03520967) and (B) downstream (Station number 03520968) right-bank 

water-quality monitors.

(A)

 Apr

2006

 Aug

2006

 Dec

2006

 Apr

2007

 Aug

2007

 Dec

2007

 Apr

2008

0

100

200

300

400

500

600

700

800

900

1,000

TURBIDITY, IN FORMAZIN NEPHELOMETRIC UNITS

0

100

200

300

400

500

600

700

800

900

1,000

TURBIDITY, IN FORMAZIN NEPHELOMETRIC UNITS

(A)

(B)
18 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

Figure 10. Turbidity data (15-minute interval) collected from the unnamed tributary at the (A) upstream 

(Station number 03520980) and (B) downstream (Station number 03520981) water-quality monitors, 

Tazewell County, Virginia.

 Apr

2006

 Aug

2006

 Dec

2006

 Apr

2007

 Aug

2007

 Dec

2007

 Apr

2008

0

200

400

600

800

1,000

1,200

1,400

1,600

TURBIDITY, IN FORMAZIN NEPHELOMETRIC UNITS TURBIDITY, IN FORMAZIN NEPHELOMETRIC UNITS

(A)

(B)

0

200

400

600

800

1,000

1,200

1,400

1,600
Water-Quality Patterns in Indian Creek and the Unnamed Tributary 19

Figure 11. Exceedance 

plots for left-bank 

turbidity collected at the 

(A) upstream Indian Creek 

water-quality monitor 

(Station number 03520967) 

and (B) downstream 

Indian Creek water-quality 

monitor (Station number 

03520968) during the preconstruction, construction, 

and post-construction 

phases, Tazewell County, 

Virginia. 

PERCENT OF TIME TURBIDITY IS EQUALED OR EXCEEDED

100

90

80

70

60

50

40

30

20

10

0

PERCENT OF TIME TURBIDITY IS EQUALED OR EXCEEDED

100

90

80

70

60

50

40

30

20

10

0

(A)

(B)

Construction

Post-construction

Pre-construction

Construction

Post-construction

Pre-construction

0.1 1 10 100 1,000

TURBIDITY, IN FORMAZIN NEPHELOMETRIC UNITS

Range of median turbidity values: 1.3 FNU 

Range of median turbidity values: 3.0 FNU 
20 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

Figure 12. Exceedance 

plots for right-bank 

turbidity collected 

at the (A) upstream 

Indian Creek waterquality monitor (Station 

number 03520967) and 

(B) downstream Indian 

Creek water-quality 

monitor (Station number 

03520968) during the 

pre-construction, 

construction, and postconstruction phases, 

Tazewell County, 

Virginia. 

PERCENT OF TIME TURBIDITY IS EQUALED OR EXCEEDED

100

90

80

70

60

50

40

30

20

10

0

PERCENT OF TIME TURBIDITY IS EQUALED OR EXCEEDED

100

90

80

70

60

50

40

30

20

10

0

0.1 1 10 100 1,000

TURBIDITY, IN FORMAZIN NEPHELOMETRIC UNITS

(A)

(B)

Construction

Post-construction

Pre-construction

Construction

Post-construction

Pre-construction

Range of median turbidity values: 1.3 FNU 

Range of median turbidity values: 1.8 FNU 
Water-Quality Patterns in Indian Creek and the Unnamed Tributary 21

Figure 13. Exceedance 

plots for turbidity 

collected at the (A) upstream unnamed 

tributary water-quality 

monitor (Station 

number 03520980) 

and (B) downstream 

unnamed tributary 

water-quality monitor 

(Station number 

03520981) during the 

pre-construction, 

construction, and postconstruction phases, 

Tazewell County, 

Virginia. 

PERCENT OF TIME TURBIDITY IS EQUALED OR EXCEEDED

100

90

80

70

60

50

40

30

20

100

PERCENT OF TIME TURBIDITY IS EQUALED OR EXCEEDED

100

90

80

70

60

50

40

30

20

100

0.1

1 10 100 1,000

TURBIDITY, IN FORMAZIN NEPHELOMETRIC UNITS

(A)

(B)

Construction

Post-construction

Pre-construction

Construction

Post-construction

Pre-construction

Range of median turbidity values: 3.0 FNU 

Range of median turbidity values: 5.7 FNU 
22 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

the pipeline crossing activities, (August 4, 2006, through 

August 7, 2006), however, reveals that turbidity conditions 

did increase for a short time (fig. 14). On August 4, 2006, the 

pipeline crossing activities included the installation of flowcontrol measures and blasting of the pipeline crossing. The 

installation of the flow-control measures and subsequent channel blasting resulted in one elevated turbidity measurement of 

460 FNU and several slightly elevated turbidity values relative to upstream conditions (fig. 14). The channel trenching, 

pipeline installation, backfilling of the trench, and removal of 

flow-control measures resulted in the turbidity measurements 

collected on August 5, 2006 (fig. 14). The elevated turbidity 

conditions observed following the removal of the flow-control 

measures were consistent with the literature accounts of the 

dry-cut pipeline crossing technique (Reid and others, 2002). 

Although turbidity (suspended sediment) was generated during 

the construction of the unnamed tributary pipeline crossing, 

the turbidity values were significantly lower than the turbidity 

values generated during natural rainfall-runoff events within 

this tributary (fig. 15). The turbidity values associated with 

the rainfall-runoff event that occurred on August 7, 2006 are 

(1) consistent both upstream and downstream, indicating that 

the freshly constructed crossing was not a substantial source 

of sediment during this runoff event, and (2) representative of 

turbidity values routinely generated during runoff-events. 

A signed-rank test was used to directly compare upstream 

and downstream turbidity values measured during the three 

phases of pipeline construction. The signed-rank test determines whether the median value of the paired differences of 

upstream and downstream turbidity values is equal to zero. 

The results of the signed-rank test are presented in table 4. 

The signed-rank test on the pre-construction paired differences 

revealed that the median paired differences for Indian Creek 

(left bank and right bank) and the unnamed tributary were all 

significantly different from zero (p < 0.001). The median preconstruction paired differences were –0.3, –0.5, and –1.0 FNU 

for the Indian Creek left bank and right bank and the unnamed 

tributary, respectively. The results from the pre-construction 

paired differences indicate that there is typically a slight 

increase (1 FNU or less) in turbidity as water passes from the 

upstream monitors to the downstream monitors. The signedrank test on the construction paired differences revealed that 

Figure 14. Turbidity data (15-minute interval) collected from the unnamed tributary at the 

upstream (Station number 03520980) and downstream (Station number 03520981) water-quality 

monitors during active pipeline construction August 4–7, 2006, Tazewell County, Virginia.

TURBIDITY, IN FORMAZIN NEPHELOMETRIC UNITS

 0

50

100

150

200

250

300

350

400

450

08/04/2006 08/05/2006 08/06/2006 08/07/2006

flow diversion 

begins

blasting across

trench

active 

trenching

pipeline 

installed

flow diversion 

removed

settling tank 

emptied

Downstream turbidity

Upstream turbidity
Water-Quality Patterns in Indian Creek and the Unnamed Tributary 23

the median percent differences for Indian Creek (left bank and 

right bank) and the unnamed tributary were all significantly 

different from zero (p < 0.001). The median construction paired 

differences values were –1.3, –0.7, and 1.7 FNU for the Indian 

Creek left bank and right bank and the unnamed tributary, 

respectively. The result from the construction period paired 

Figure 15. Turbidity data (15-minute interval) collected from the unnamed tributary at the 

upstream (Station number 03520980) and downstream (Station number 03520981) water-quality 

monitors during active pipeline construction August 4–8, 2006, Tazewell County, Virginia.

TURBIDITY, IN FORMAZIN NEPHELOMETRIC UNITS

 0

200

400

600

800

1,000

1,200

08/04/2006 08/05/2006 08/06/2006 08/07/2006 08/08/2006

Downstream turbidity

Upstream turbidity

Table 4. Signed-rank test results for turbidity differences from 

paired upstream and downstream turbidity values from Indian 

Creek and unnamed tributary. 

[Values presented are the median paired difference in upstream and downstream turbidity, in Formazin Nephelometric Units, and the associated signedrank test p-value in parentheses] 

Indian Creek 

left bank

Indian Creek 

right bank

Unnamed 

tributary

Pre-Construction –0.3

(< 0.001)

–0.5

(< 0.001)

–1.0

(< 0.001)

Construction –1.3

(< 0.001)

–0.7

(< 0.001)

1.7

(< 0.001)

Post-Construction 0.2

(< 0.001)

0.1

(< 0.001)

0

(0.055)

differences from the Indian Creek left-bank monitors indicates 

that turbidity values increased 1 FNU as water moved below 

the pipeline construction. This same pattern in construction 

paired differences from the right-bank monitors was observed; 

however, the difference relative to the pre-construction median 

paired difference was only 0.2 FNU. Conversely, the signedrank test results for the unnamed tributary indicate that turbidity values decreased 1.7 FNU downstream from the upstream 

monitor, which is a shift of 2.7 FNU relative to pre-construction conditions. The signed-rank test on the post-construction 

paired differences revealed that the median of the paired 

differences for Indian Creek (left bank and right bank) were all 

significantly different from zero. The median post-construction 

paired differences were 0.2 and 0.1 FNU for the Indian Creek 

left bank and right bank, respectively. The signed-rank test 

on the unnamed tributary post-construction paired differences 

revealed that the median of the paired differences was not 

significantly different from zero. The median post-construction 

paired difference was 0.0 FNU for the unnamed tributary. 

These post-construction turbidity conditions were similar to the 

observed pre-construction conditions. 
24 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

The results from the signed-rank test analysis help to 

determine whether the pipeline crossing affected downstream 

sediment conditions in Indian Creek and the unnamed tributary. In Indian Creek, the paired differences of upstream and 

downstream turbidity values and the associated signed-rank 

test all indicate that more sediment entered the study reach 

during the construction phase than during the pre-construction 

and post-construction phases. The signed-rank test results 

also indicate that a more pronounced sediment source exists 

between the upstream and downstream left-bank monitors. 

Although this result is significant, the magnitude of the difference is small. The discrepancy between the downstream leftand right-bank monitors is discussed further in the “Conceptual Model for Indian Creek Turbidity Patterns” section of this 

report. In the unnamed tributary, the pipeline crossing did not 

increase turbidity conditions downstream from the pipeline 

crossing on the basis of the signed-rank test analysis of the 

three construction periods. 

Boxplots of the paired differences for each month of 

the study were generated for the Indian Creek and unnamed 

tributary monitors. These boxplots show the distribution of 

the monthly paired differences (represented by the 10th, 25th, 

50th, 75th, and 90th percentiles). For comparison, the monthly 

differences for the paired turbidity values collected at the 

two upstream Indian Creek monitors (left and right bank) are 

presented in figure 16. The black horizontal line that passes 

through all of the monthly boxplots is the locally weighted 

scatterplot smoothing (LOWESS) (Helsel and Hirsch, 1992) 

best fit of the monthly medians. The LOWESS best-fit line 

was used to identify temporal patterns between the monthly 

medians. This boxplot of the upstream paired differences 

indicates that the majority of the monthly paired differences, for the entire study period, occurred between 2.0 and 

–2.0 FNU. This result strongly indicates that the combination 

of variability between the instruments and the natural variability in the channel accounts for ± 2 FNU. Paired differences 

within the ± 2 FNU range should be considered environmental 

and instrument noise, whereas values outside of this range 

may indicate a measurable change in turbidity. The boxplot of monthly paired differences for the Indian Creek left 

bank (upstream minus downstream) shows that most of the 

paired differences occur within the ± 2 FNU range; however, 

June 2006 through August 2006 had paired differences that 

exceeded this –2.0 FNU, indicating a sustained sediment 

input downstream from the upstream Indian Creek monitors 

(fig. 17A). This pattern of sediment input from June 2006 

through August 2006 was observed in the paired differences 

from the upstream and downstream right-bank monitors 

(fig. 17B). The vast majority of the right-bank turbidity paired 

differences are within the ± 2 FNU range. The boxplot of 

Figure 16. Monthly differences for paired turbidity values collected at the leftbank and right-bank upstream Indian Creek water-quality monitors (Station number 

03520967, fig. 3), Tazewell County, Virginia. Turbidity paired difference equals left-bank 

turbidity minus right-bank turbidity. The black line represents the LOWESS smoothed 

fit line through the monthly medians. 

4/06 6/06 8/06 10/06 12/06 2/07 4/07 6/07 8/07 10/07 12/07 2/08 4/08

-5

-4

-3

-2

-1

0

1

2

3

EXPLANATION

75th

25th

50th

90th

10th

Percentile—Percentage of

values equal to or less than

indicated values

TURBIDITY PAIRED DIFFERENCE, IN FORMAZIN NEPHELOMETRIC UNITS

MONTH

(median)
Water-Quality Patterns in Indian Creek and the Unnamed Tributary 25

Figure 17. Monthly differences for paired turbidity values collected at the (A) leftbank and (B) right-bank monitors located upstream (Station number 03520967, fig. 3) 

and downstream (Station number 03520968) of the pipeline crossing under Indian 

Creek, Tazewell County, Virginia. Turbidity paried difference equals left-bank upstream 

turbidity minus left-bank downstream turbidity. The black line represents the LOWESS 

smoothed fit line through the monthly medians. 

4/06 6/06 8/06 10/06 12/06 2/07 4/07 6/07 8/07 10/07 12/07 2/08 4/08

-5

-4

-3

-2

-1

0

1

2

3

4

TURBIDITY PAIRED DIFFERENCE, IN FORMAZIN NEPHELOMETRIC UNITS

EXPLANATION

75th

25th

50th

90th

10th

Percentile—Percentage of

values equal to or less than

indicated values

4/06 6/06 8/06 10/06 12/06 2/07 4/07 6/07 8/07 10/07 12/07 2/08 4/08

-5

-4

-3

-2

-1

0

1

2

3

TURBIDITY PAIRED DIFFERENCE, IN FORMAZIN NEPHELOMETRIC UNITS

(A)

(B)

MONTH

(median)
26 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

monthly paired differences for the unnamed tributary show 

that turbidity in the tributary is highly variable compared to 

turbidity paired differences for Indian Creek, with a range 

that typically extends ± 10 FNU (fig. 18). The monthly paired 

differences indicate that turbidity conditions improved (that 

is, turbidity decreased at the downstream monitor) during the 

pipeline construction and that the construction paired differences are indistinguishable from the remaining monthly 

paired differences.

As part of the assessment of long-term turbidity patterns, 

exceedance plots of measured turbidity values, signed-rank 

test of turbidity paired differences, and monthly boxplots of 

turbidity paired differences were used to determine whether 

the Indian Creek and unnamed tributary pipeline crossings 

resulted in increased turbidity levels downstream from the 

crossings. These three analytical evaluations of the measured 

turbidity patterns provided consistent results for turbidity 

conditions for both Indian Creek and the unnamed tributary. 

In Indian Creek, turbidity significantly increased downstream 

from the pipeline crossing. The greatest increase in downstream turbidity occurred during the construction phase. 

Although the results for left- and right-bank turbidity patterns 

were consistent, the turbidity patterns were most pronounced 

along the left bank. This discrepancy between the left- and 

right-bank turbidity patterns is discussed further in the “Conceptual Model for Indian Creek Turbidity Patterns” section of 

this report. In the unnamed tributary, turbidity values downstream from the pipeline crossing were measurably elevated 

for short durations during active pipeline-crossing construction, August 4–6, 2006; however, the sediment generated during this period, as indicated by the increase in turbidity, was 

substantially lower than the turbidity levels that are generated 

during typical runoff events. On the unnamed tributary, the 

long-term patterns in turbidity, collected during the construction phase, indicate that turbidity significantly decreased 

downstream from the pipeline crossing. 

Utility of the Turbidity-Input Warning System

The turbidity-input warning system required by the 

USFWS and subsequently established by East Tennessee 

Natural Gas and the USGS was instrumental in ensuring the 

integrity of the ecology of Indian Creek and the unnamed 

tributary. A turbidity warning occurred when downstream 

turbidity was either 6 FNU, or 15 percent (see “TurbidityInput Warning System” section for additional details) greater 

than the corresponding upstream turbidity value, sustained for 

Figure 18. Monthly differences for paired turbidity values collected at the upstream 

(Station number 03520980) and downstream (Station number 03520981, fig. 3) 

unnamed tributary water-quality monitors, Tazewell County, Virginia. Turbidity paired 

difference equals upstream turbidity minus downstream turbidity. The black line 

represents the LOWESS smoothed fit line through the monthly medians. 

4/06 6/06 8/06 10/06 12/06 2/07 4/07 6/07 8/07 10/07 12/07 2/08 4/08

-50

-40

-30

-20

-10

0

10

20

30

MONTH

EXPLANATION

75th

25th

50th

90th

10th

Percentile—Percentage of

values equal to or less than

indicated values

TURBIDITY PAIRED DIFFERENCE, IN FORMAZIN NEPHELOMETRIC UNITS

(median)
Water-Quality Patterns in Indian Creek and the Unnamed Tributary 27

a period of 1 hour. Once a threshold was exceeded, the on-site 

manager for East Tennessee Natural Gas would investigate 

Indian Creek below the upstream monitors for incoming 

sediment. If incoming sediment was not present, then East 

Tennessee Natural Gas would contact the USGS to check for 

turbidity-equipment problems such as fouling from the accumulation of debris on the water-quality monitoring sonde. An 

example of the warnings received each month for exceeding 

the downstream-turbidity thresholds is provided in figure 19. 

This figure shows that during each month, between 0 and 

38 warnings (0 to 1.45 percent of the collected turbidity unit 

values) occurred throughout the period of study. During the 

construction phase, 16 to 38 alarms occurred each month, and 

were subsequently investigated. Most of the warnings were 

determined to be caused by fouling of the turbidity probe. 

On August 19, 2006, the turbidity-input warning system captured a substantial sediment-input event. An intensive rainfall event in the Indian Creek watershed caused 

upland surface-water runoff and associated sediment transport from the Jewell Ridge pipeline right-of-way. Although 

sediment- and erosion-control measures were in place, this 

runoff and sediment transport overwhelmed the existing 

controls and entered an ephemeral unnamed tributary approximately 350 feet upstream from the right-bank monitor on 

Indian Creek. This runoff event delivered substantial amounts 

of suspended sediment into Indian Creek. Turbidity values 

measured at the upstream left- and right-bank monitors peaked 

at 930 and 750 FNU, respectively, whereas turbidity reached 

1,220 FNU at the downstream right-bank monitor. The 

downstream left-bank monitor was not functioning during this 

sediment-input event.

 The turbidity-warning system allowed real-time detection of sediment/turbidity input within the study reach. The 

ability for watershed managers to detect sediment input as it 

happened allowed for rapid-response corrective actions. The 

turbidity-input warning system successfully detected episodic 

exceedences of the established turbidity threshold, and helped 

to prevent occurrences of chronic long-term input of turbidity. 

One limitation of the turbidity-input warning system is that 

the conservative nature of the turbidity thresholds make the 

system highly susceptible to false-positive warnings. 

Figure 19. Monthly bar plot showing the percentage of turbidity paired differences that resulted 

in a warning for exceeding the turbidity threshold along the left bank of Indian Creek, Tazewell 

County, Virginia. The number above each bar plot represents the actual number of warnings. 

0

0.5

1.0

1.5

 1

16

23

38

 7

 5

 8

 7

13

24

PERCENT OF OBSERVATIONS

5/06 7/06 9/06 11/06 1/07 3/07 5/07 7/07 9/07 11/07 1/08 3/08

MONTH
28 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

Conceptual Model for Indian Creek 

Turbidity Patterns

This study was designed to evaluate whether the Jewell 

Ridge pipeline crossing and associated pipeline construction resulted in increased turbidity levels, thus increasing 

suspended-sediment concentrations during the construction 

phase, and to detect both real-time and long-term changes in 

turbidity conditions within the pipeline-crossing easement. 

Results obtained from all statistical and graphical analyses 

indicate that turbidity levels increased within the Indian Creek 

pipeline-crossing easement, and that these increases in turbidity were small in magnitude but occurred over a prolonged 

time period. Although these results were consistent for all 

upstream to downstream analyses, the pattern of increased 

turbidity was always more pronounced along the left side 

of the channel compared to the right side of the channel. An 

investigation into these left- and right-channel inconsistencies, 

coupled with the occurrence of the August 19, 2006, right-ofway slope failure and subsequent sediment transport, led to the 

development of an alternative conceptual model for turbidity 

patterns measured during the construction phase. The initial 

conceptual model, which was tested during this study, was that 

the pipeline crossing and nearby adjacent trenching activities would transport sediment directly into the Indian Creek 

monitoring reach. The alternative conceptual model was that 

transport of sediment from the pipeline construction right-ofway into an ephemeral unnamed tributary and subsequently 

into Indian Creek served as the primary source of turbidity/

sediment detected during the construction phase. For the 

remainder of this section, data are presented that support the 

development of this alternative conceptual model.

The ephemeral unnamed tributary (which should not be 

confused with the unnamed tributary monitored as part of 

this study) discharges into Indian Creek along the right bank, 

approximately 350 feet above the upstream water-quality monitors (fig. 20). The path of the Jewell Ridge pipeline crosses 

the headwaters of the ephemeral unnamed tributary (fig. 20). 

The effects of this ephemeral unnamed tributary on sediment 

delivery to Indian Creek were considered during the development phase of this study; however, the study was designed to 

focus on the Indian Creek pipeline crossing and it was anticipated that this ephemeral unnamed tributary would not be a 

source of construction sediment. The design of the monitoring 

network (paired upstream, downstream, left-bank, and rightbank monitors) was chosen to isolate the Indian Creek pipeline 

crossing and to account for incoming sediment from this 

ephemeral unnamed tributary; however, the August 19, 2006, 

sediment transport event showed that the pipeline construction 

activity was a substantial source of sediment in the ephemeral 

unnamed tributary. The design of the water-quality network 

that was implemented and associated data analyses allowed 

for the determination that sediment derived from this ephemeral unnamed tributary may in fact be the primary source of 

sediment that was detected within the Indian Creek pipelinecrossing easement. 

Analysis of turbidity data collected at the upstream Indian 

Creek monitors revealed that variability between turbidity data 

collected at the left- and right-bank monitors increased during 

pipeline construction. Results from a paired differences analysis (left-bank minus right-bank turbidity value) of the 50th, 

75th, 80th, 90th, 95th, and 99th percentiles for turbidity data 

collected at both upstream Indian Creek turbidity monitors are 

presented in figure 21. The 50th though the 99th percentiles 

represent turbidity values that ranged from 3 to 100 FNU during the entire period of study. During pre-construction, paired 

differences from these specified percentiles ranged from 

0.2 to 1.4 FNU, which indicates that turbidity values were 

slightly greater at the left-bank monitor. This pre-construction 

result shifted during the construction phase to a range of 1.0 

to –3.0 FNU. The paired differences for the 75th, 80th, 90th, 

and 95th percentiles were all negative, indicating that turbidity values were greater at the right-bank monitor. This result 

indicates that during elevated turbidity conditions within the 

construction period, which were typically associated with 

runoff events, the right side of the Indian Creek channel was 

more turbid than the left side of the channel. Also, this shift 

from positive paired differences during the pre-construction 

phase to negative paired differences during the construction 

phase indicates that a new sediment source was contributing 

to Indian Creek turbidity. The ephemeral unnamed tributary 

discharges to the right bank of Indian Creek 350 feet above 

the upstream monitors thereby allowing very little distance for 

mixing, which would generate the negative paired differences 

that were observed. Additionally, Indian Creek is considered 

completely mixed upstream from the confluence with the 

ephemeral unnamed tributary. The paired differences returned 

to all positive values during the post-construction phase. The 

post-construction paired differences ranged from 0 to 4 FNU, 

and the observed range for the 50th to 95th percentiles was 0.0 

to 0.1 FNU. The consistent and small observed ranges in preand post-construction paired differences indicate that Indian 

Creek is well mixed as it flows by the upstream monitors. 

Conversely, the negative paired differences observed during 

the construction phase indicate that sediment delivered from 

the ephemeral unnamed tributary primarily was detected by 

the right-bank monitor, and that the contributions from this 

tributary dissipated during the post-construction phase. 

The results of the paired differences analysis performed 

on the paired upstream left- and right-bank turbidity percentiles explain the discrepancy observed in the long-term 

analysis of left- and right-bank paired upstream and downstream data. The long-term analysis of these paired differences indicates that turbidity increased within the pipelinecrossing easement during construction; however, these results 

were more pronounced along the left channel compared to the 

results for the right side of the channel. This discrepancy is 

explained by the turbidity patterns observed at the upstream 

monitors during the construction phase. Most of the longterm analyses relied on paired differences of upstream and 

downstream turbidity data to detect change. Because turbidity 
Water-Quality Patterns in Indian Creek and the Unnamed Tributary 29

at the upstream right-bank monitor was elevated during the 

construction phase, the difference between the upstream and 

downstream right-bank monitors was minimized. Essentially, 

the turbidity that was detected by the upstream right-bank 

monitor was detected by the downstream right-bank monitor. 

Additionally, the turbidity that passed the upstream rightbank monitor was transported and subsequently mixed across 

the channel so that the downstream left-bank monitor also 

detected this turbidity. As the upstream left-bank monitor did 

not fully detect this incoming turbidity from the ephemeral 

unnamed tributary, a pronounced and statistically significant 

result was obtained, which indicated that a sediment input 

occurred along the left bank. 

The following conclusions can be drawn from the alternative conceptual model:

1. Turbidity values significantly increased within the 

pipeline-crossing easement during the construction phase;

2. The primary source of this turbidity increase can be linked 

to sediment delivered from the ephemeral unnamed tributary; and

3. The bored pipeline crossing had little to no effect on sediment conditions in Indian Creek, and sediment transport 

from the upland pipeline right-of-way into the ephemeral 

unnamed tributary was the primary source for the turbidity 

increases observed in the pipeline-crossing easement.

Figure 20. The Indian Creek and unnamed tributary monitoring network as well as the ephemeral unnamed 

tributary, Tazewell County, Virginia.

Ephemeral Unnamed

Tributary

EXPLANATION

MONITORING STATION

0

0

1 2 MILES

1 2 KILOMETERS

03520968

03520981

03520967

03520980

Unnamed Tributary

Jewell Ridge Pipeline

631

Busthead

Van Dyke

Cedar Bluff

Indian Creek

81°45'40" 81°44'40" 81°43'40" 81°42'40" 81°41'39"

37°7'57"

37°6'57"

37°5'56"

37°4'56"
30 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

Figure 21. Boxplots of turbidity paired differences for turbidity collected at the left-bank 

and right-bank upstream Indian Creek water-quality monitors (Station number 03520967), 

Tazewell County, Virginia. Turbidity paired difference equals left-bank turbidity minus 

right-bank turbidity for values at the 50th, 75th, 80th, 90th, 95th, and 99th percentiles. 

Pre-construction Construction Post-construction

-3

-2

-1

0

1

2

3

4

EXPLANATION

75th Percentile

25th Percentile

50th Percentile

Largest paired difference value less

than or equal to the upper quartile 

plus 1.5 times the interquartile range

Smallest paired difference value 

greater than or equal to the lower 

quartile minus 1.5 times the 

interquartile range

Paired difference exceeding upper or 

lower quartile by more than 

1.5 times the interquartile range

TURBIDITY PAIRED DIFFERENCE, IN FORMAZIN NEPHELOMETRIC UNITS

(median)
Summary and Conclusions 31

These conclusions are consistent with those in the literature 

regarding the effect of the HDD technique on downstream 

suspended-sediment conditions. The HDD technique has been 

shown to have little to no impact on downstream suspendedsediment conditions (Reid and others, 2002; Lévesque and 

Dubé, 2007). The HDD technique bores a pipeline crossing 

at least 5 feet beneath the bottom of the stream. The area of 

the boring is bordered by extensive silt fencing and hay bails, 

which also reduce the likelihood that sediment will be transported into the crossing. No sediments were ever observed to 

directly wash off the Indian Creek pipeline crossing construction site. Conversely, it has been shown that the greatest risk 

associated with sediment transport during the application of 

HDD is the runoff and associated sediment transport from the 

upland pipeline right-of-way into nearby drainages (Reid and 

others, 2002; Lévesque and Dubé, 2007). 

Study Limitations

Although the establishment of the turbidity-monitoring 

network enabled short-term and long-term evaluation of 

the pipeline crossing beneath Indian Creek and through the 

unnamed tributary, several confounding factors affected the 

statistical analysis to identify changes in turbidity conditions. 

These factors include (1) an abbreviated pre-construction 

monitoring period, (2) loss of turbidity data through fouling, 

(3) uncontrolled sediment sources upstream from the monitoring reach, and (4) routing of extracted bore water downstream 

from the monitoring reach. 

Pre-construction monitoring was a critical component 

in determining the overall influence of the pipeline crossing 

on downstream water-quality conditions. The objective of the 

pre-construction monitoring period was to quantify the extent 

of environmental and instrument variability in instream waterquality properties. Ideally, the pre-construction monitoring 

period would have been long enough to capture a wide range 

of hydrologic conditions. The pre-construction monitoring 

period was limited to 34 days, however, during which no substantial runoff event occurred within the Indian Creek Basin. 

As a result, the natural and instrument variability associated 

with turbidity in Indian Creek is representative of the 34-day 

pre-construction monitoring period but underrepresents the 

complete range of conditions.

The use of continuously collected turbidity data was 

essential to the real-time monitoring of water-quality conditions in Indian Creek and the unnamed tributary. During the 

study period, turbidity conditions were intensively monitored 

at an average rate of 2,600 and 2,400 turbidity observations 

per month from Indian Creek and the unnamed tributary, 

respectively. The turbidity monitoring instrument, however, 

was prone to fouling caused by several factors including 

instream debris (leaves and sediment), biofouling (algal 

growth and presence of macro-invertebrates), and electronic 

drift. Fouling of the Indian Creek and the unnamed tributary 

monitors resulted in an average monthly loss of turbidity data 

of 10 and 20 percent, respectively. The USGS, in response to 

the elevated rate of fouling on the unnamed tributary monitors, 

increased the maintenance to once every 2 weeks instead of 

once every 4 weeks. Additionally, the occurrence of turbidityinstrumentation fouling typically resulted in an exceedence of 

the established turbidity threshold, which had to be investigated to ensure the warning was not a result of sediment input. 

 On August 19, 2006, excessive runoff and associated 

sediment transport from the upland Jewell Ridge pipeline 

construction right-of-way overwhelmed the upland slope 

and entered an ephemeral unnamed tributary, which brought 

substantial amounts of suspended sediment into Indian Creek 

350 feet upstream from the monitoring site. The primary 

concern regarding the influence of this sediment input on the 

success of the monitoring effort is that it occurred upstream 

from the upstream turbidity monitors. The Indian Creek 

monitoring network was designed to evaluate the effects of 

the pipeline crossing on downstream values of turbidity; the 

upstream monitors were intended to represent non-pipelinederived turbidity. There is no way to determine how long this 

sediment-input event influenced the analysis of the differences 

of paired-turbidity values. 

During the construction of the Indian Creek pipeline 

crossing, HDD was used to drill under Indian Creek. As part 

of the drilling, water and associated sediment were pumped 

from the drill site and stored in a series of two on-site settling tanks. Most of the suspended material settled out within 

the first settling tank. This water was then passed to a second settling tank where additional deposition of particulate 

constituents occurred. The stored water was then released 

through a filter bag onto a grassy field that drained into Indian 

Creek. The discharge location selected for the release in the 

grassy field caused the release water to flow into Indian Creek 

downstream from the downstream monitor. Thus, it cannot be 

determined whether this activity affected water-quality conditions in Indian Creek. 

Summary and Conclusions

In 2006, the USGS, in cooperation with East Tennessee 

Natural Gas and USFWS, began a study to monitor the effects 

of construction of the Jewell Ridge Lateral natural gas pipeline 

on suspended-sediment concentrations below the pipeline 

crossing beneath Indian Creek and through an unnamed 

tributary to Indian Creek in Tazewell County, Virginia. The 

Biological Opinion, prepared by the USFWS, required that 

turbidity conditions be intensively monitored below the 

pipeline crossings because of the presence of threatened and 

endangered mussel species. Indian Creek is listed as one of the 

Virginia Department of Game and Inland Fisheries’ designated Threatened and Endangered Species Waters and contains federally designated critical habitat for two endangered 

freshwater mussel species, purple bean (Villosa perpurpurea) 

and rough rabbitsfoot (Quadrula cylindrical strigillata). 
32 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

Additionally, Indian Creek contains the last known reproducing population of the tan riffleshell (Epioblasma florentina 

walkeri). The primary objective of the USGS monitoring effort 

was to identify whether the construction of the Indian Creek 

pipeline crossing would adversely impact the suspendedsediment concentrations, using turbidity as a surrogate. The 

specific study objectives were to (1) develop a continuous turbidity monitoring network that attempted to measure real-time 

changes in suspended-sediment conditions (using turbidity as 

a surrogate) downstream from the pipeline crossing in Indian 

Creek and the unnamed tributary to Indian Creek, and (2) provide continuous turbidity data that allow for the development 

of a turbidity-input warning system and assessment of longterm changes in turbidity conditions.

Water-quality conditions were assessed using continuous 

water-quality monitors deployed upstream and downstream 

from the pipeline crossings in Indian Creek and the unnamed 

tributary. In Indian Creek, two water-quality monitoring 

sondes were suspended from a boom upstream from the 

pipeline crossing so that one monitor was submersed near the 

left bank and the second monitor was submersed near the right 

bank. Two additional water-quality monitoring sondes were 

suspended from a boom downstream from the pipeline crossing so that one monitor was submersed near the left bank and 

the second monitor was submersed near the right bank. These 

paired upstream and downstream monitors were outfitted with 

turbidity, pH, specific conductance, and water-temperature 

sensors. In the unnamed tributary, two water-quality monitoring sondes were deployed upstream and downstream from 

the pipeline crossing. The paired upstream and downstream 

monitors were outfitted with turbidity, specific-conductance, 

water-temperature, and water-level sensors. Water-quality 

data were collected continuously (every 15 minutes) during 

three phases of the pipeline construction: pre-construction 

(April 28, 2006, through May 31, 2006), during construction 

(June 1, 2006, through August 31, 2006), and post-construction (September 1, 2006, through April 9, 2008), transmitted 

hourly via satellite transmission, and made publicly available 

on the USGS NWIS Web page (http://waterdata.usgs.gov/va/

nwis/nwis).

Continuous turbidity data were evaluated at various time 

steps to determine if the construction of the pipeline crossings 

had an effect on downstream suspended-sediment conditions 

in Indian Creek and the unnamed tributary. Hourly evaluations of paired upstream- and downstream-turbidity data 

were performed by the on-site managers from East Tennessee 

Natural Gas to ensure that the difference in the paired turbidity values was within the established threshold. This threshold 

required that downstream turbidity values could not be 6 FNU, 

or 15 percent greater than the paired upstream turbidity value. 

If the established threshold was exceeded for a sustained 

period of 1 hour, then an on-site inspection was required to 

ensure sediment was not actively being transported from the 

construction site. At the monthly and phase-of-construction 

time step, a signed-rank test was performed on the paired differences of the upstream and downstream turbidity values to 

test the null hypothesis that the median paired difference value 

was equal to zero. If the null hypothesis was accepted, then the 

construction of pipeline crossing had no effect on downstream 

sediment conditions; conversely, if the null hypothesis was 

rejected, then it would be concluded that pipeline construction 

did affect downstream sediment conditions. 

The results of this intensive water-quality monitoring effort indicate that values of turbidity in Indian Creek 

increased significantly between the upstream and downstream 

water-quality monitors during the construction of the Jewell 

Ridge pipeline. The magnitude of the turbidity increase, however, is small (less than 2 FNU). The results from this study 

indicate that the source of the increased turbidity, detected 

within the pipeline-crossing easement during construction, 

primarily can be linked to sediment delivered to Indian Creek 

from an ephemeral unnamed tributary. The primary source 

of the sediment in the ephemeral unnamed tributary is from 

runoff from the upland pipeline construction right-of-way. 

Conversely, turbidity conditions in the unnamed tributary were 

not adversely altered during the construction of the pipeline 

crossing. Turbidity data collected during the active construction of the dry-cut pipeline crossing through the unnamed 

tributary indicated that turbidity increased downstream; however, the increase in turbidity values was shown to be minimal compared to the turbidity values obtained during natural 

runoff events. 

Acknowledgments

Sincere thanks are extended to the following USGS 

employees who maintained the Indian Creek water-quality 

monitoring network during this study: Michael R. Eckenwiler, 

Donna S. Justus, Harold G. Henderlite, Dennis W. Adams, and 

Brian A. Hasty. In addition, the authors wish to thank Karen R. 

Ryberg and Paul D. Ankcorn of the USGS for providing technical reviews of this report. 

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Appendixes 1–6 

The following appendixes provide graphs showing continuous water-quality data collected from 

Indian Creek and an unnamed tributary, Tazewell County, Virginia.

Appendix 1 37

Appendix 1. Continuous water-quality data (15-minute 

interval) collected from Indian Creek, Tazewell County, 

Virginia, at the upstream (Station number 03520967) 

left-bank water-quality monitor: (A) pH, (B) specific 

conductance, and (C) water temperature.

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

pH, STANDARD UNITS

50

100

150

200

250

300

350

400

450

500

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

-5

0

5

10

15

20

25

30

WATER TEMPERATURE, IN DEGREES CELSIUS

4/06 8/06 12/06 4/07 8/07 12/07 4/08

DATE

(A)

(B)

(C)

Figure A1. pH (A), specific conductance (B), and water temperature (C) data (15-minute interval) collected from 

Indian Creek, Tazewell County, Virginia, at the upstream (Station number 03520967) left-bank water-quality monitor. 
38 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

pH, STANDARD UNITS

50

100

150

200

250

300

350

400

450

500

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

-5

0

5

10

15

20

25

30

WATER TEMPERATURE, IN DEGREES CELSIUS

4/06 8/06 12/06 4/07 8/07 12/07 4/08

DATE

(A)

(B)

(C)

Figure A2. pH (A), specific conductance (B), and water temperature (C) data (15-minute interval) collect

Indian Creek, Tazewell County, Virginia, at the upstream (Station number 03520967) right-bank water-qua

Appendix 2. Continuous water-quality data (15-minute 

interval) collected from Indian Creek, Tazewell County, 

Virginia, at the upstream (Station number 03520967) 

right-bank water-quality monitor: (A) pH, (B) specific 

conductance, and (C) water temperature.
Appendix 3 39

Appendix 3. Continuous water-quality data (15-minute 

interval) collected from Indian Creek, Tazewell County, 

Virginia, at the downstream (Station number 03520968) 

left-bank water-quality monitor: (A) pH, (B) specific 

conductance, and (C) water temperature.

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

pH, STANDARD UNITS

50

100

150

200

250

300

350

400

450

500

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

-5

0

5

10

15

20

25

30

WATER TEMPERATURE, IN DEGREES CELSIUS

4/06 8/06 12/06 4/07 8/07 12/07 4/08

DATE

(A)

(B)

(C)

Figure A3. pH (A), specific conductance (B), and water temperature data (C) (15-minute interval) collected from 

Indian Creek, Tazewell County, Virginia, at the downstream (Station number 03520968) left-bank water-quality monitor. 
40 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

Appendix 4. Continuous water-quality data (15-minute 

interval) collected from Indian Creek, Tazewell County, 

Virginia, at the downstream (Station number 03520968) 

right-bank water-quality monitor: (A) pH, (B) specific 

conductance, and (C) water temperature.

6.0

6.5

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0

pH, STANDARD UNITS

50

100

150

200

250

300

350

400

450

500

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

-5

0

5

10

15

20

25

30

WATER TEMPERATURE, IN DEGREES CELSIUS

4/06 8/06 12/06 4/07 8/07 12/07 4/08

DATE

(A)

(B)

(C)

Figure A4. pH (A), specific conductance (B), and water temperature (C) data (15-minute interval) colle

Indian Creek, Tazewell County, Virginia, at the downstream (Station number 03520968) right-bank wate
Appendix 5 41

Appendix 5. Continuous 

water-quality data 

(15-minute interval) 

collected from the 

unnamed tributary, 

Tazewell County, Virginia, 

at the upstream (Station 

number 03520980) 

water-quality monitor: 

(A) specific conductance 

and (B) water temperature.

200

300

400

500

600

700

800

900

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

4/06 8/06 12/06 4/07 8/07 12/07 4/08

-5

0

5

10

15

20

25

30

WATER TEMPERATURE, IN DEGREES CELSIUS

(A)

(B)

Figure A5. Specific conductance (A), and water temperature (B) data (15-minute interval) collected from 

the unnamed tributary at the upstream (Station number 03520980) water-quality monitor, Tazewell County, 

Virginia. 

DATE
42 Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08

Appendix 6. Continuous 

water-quality data 

(15-minute interval) 

collected from the 

unnamed tributary, 

Tazewell County, Virginia, 

at the downstream 

(Station number 03520981) 

water-quality monitor: 

(A) specific conductance 

and (B) water temperature.

200

300

400

500

600

700

800

900

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

4/06 8/06 12/06 4/07 8/07 12/07 4/08

0

5

10

15

20

25

30

WATER TEMPERATURE, IN DEGREES CELSIUS

DATE

Figure A6. Specific conductance (A), and water temperature (B) data (15-minute interval) collected from 

the unnamed tributary at the downstream (Station number 03520981) water-quality monitor, Tazewell County,

Virginia. 

(A)

(B)
Prepared by:

USGS Publishing Network

Raleigh Publishing Service Center

3916 Sunset Ridge Road

Raleigh, NC 27607

For additional information about this publication, contact:

Douglas L. Moyer, Supervisory Hydrologist

USGS Virginia Water Science Center

1730 East Parham Road

Richmond, VA 23228

email: dlmoyer@usgs.gov

Or visit the USGS Virginia Water Science Center Web site at:

http://va.water.usgs.gov/
Moyer and Hyer—Continuous Turbidity Monitoring in the Indian Creek Watershed, Tazewell County, Virginia, 2006–08—Scientific Investigations Report 2009–5085

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