Prepared in cooperation with the North Carolina Department of Environment and Natural

Resources, Division of Water Resources

Documentation of Data Collection in Currituck

Sound, North Carolina and Virginia, 2006–2007

Open-File Report 2008–1147
Cover. Currituck Sound at sunset, November 18, 2007, looking west across the sound (photograph used with permission by Damien P. Ossi).
Documentation of Data Collection in Currituck Sound, 

North Carolina and Virginia, 2006–2007

By Jason M. Fine

Prepared in cooperation with the North Carolina Department of Environment and 

Natural Resources, Division of Water Resources

Open-File Report 2008–1147

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2008

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Fine, J.M., 2008, Documentation of data collection in Currituck Sound, North Carolina and Virginia, 2006–2007: 

U.S. Geological Survey Open-File Report 2008–1147, 11 p. (available only online at http://pubs.water.usgs.gov/

ofr2008-1147/)
iii

Contents

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

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

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

Study Area..............................................................................................................................................3

Data Collection...............................................................................................................................................4

Water Elevation, Water Velocity, and Discharge ............................................................................4

Continuous Water-Quality Data..........................................................................................................7

Water-Quality Samples ........................................................................................................................8

Quality Assurance and Data Archival ...............................................................................................8

Summary..........................................................................................................................................................9

Acknowledgments.........................................................................................................................................9

References....................................................................................................................................................10

Figures

1. Locations of Currituck Sound and hydrologic and water-quality data-collection 

sites in North Carolina and Virginia, 2006–2007.......................................................................2

2. Summary of continuous data collected at study sites in and around 

Currituck Sound, North Carolina and Virginia, 2006–2007 .....................................................5

Tables

1. Description of data-collection sites in and around Currituck Sound 

in North Carolina and Virginia, 2006–2007 ................................................................................4

2. Description of data collected in and around Currituck Sound in North Carolina 

and Virginia, 2006–2007................................................................................................................7

3. Analytical methods used to analyze the water-quality samples collected in 

and around Currituck Sound in North Carolina and Virginia, 2006–2007.............................8

4. Number of complete days of continuous record data collected in and around 

Currituck Sound in North Carolina and Virginia from January 2006 

through September 2007..............................................................................................................9
iv

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

Area

square foot (ft2

) 0.0929 square meter (m2)

square mile (mi2

) 2.590 square kilometer (km2)

Flow

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)

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

(NAVD 88).

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

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

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

(μS/cm at 25 °C).

Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) 

or micrograms per liter (μg/L).

Abbreviations and Acronyms:

ADVM acoustic Doppler velocity meter

AIWW Atlantic Intracoastal Waterway

DWR Division of Water Resources

ECSU Elizabeth City State University

FNU Formazin Nephelometric Unit

FWS U.S. Fish and Wildlife Service

IMS The University of North Carolina at Chapel Hill Institute 

 of Marine Sciences

NERR North Carolina National Estuarine Research Reserve

NWIS National Water Information System

NWQL National Water Quality Laboratory

RM river mile

SAV submerged aquatic vegetation

USACE U.S. Army Corps of Engineers

USGS U.S. Geological Survey
Abstract

During 2006 and 2007, scientists from Elizabeth City 

State University, North Carolina Estuarine Research Reserve, 

the U.S. Fish and Wildlife Service, and the U.S. Geological 

Survey collected hydrologic and water-quality data at 

nine sites in and around Currituck Sound. Hydrologic and 

water-quality data were collected at five tributary sites—the 

Northwest River near Moyock, Tull Creek near Currituck, 

and Intracoastal Waterway near Coinjock in North Carolina, 

and the Albemarle and Chesapeake Canal near Princess 

Anne, and the North Landing River near Creeds in Virginia. 

In addition, data were collected at one site at the mouth of 

Currituck Sound (Currituck Sound at Point Harbor, North 

Carolina). Only water-quality data were collected at three 

sites in Currituck Sound and Back Bay—Currituck Sound 

near Jarvisburg, and Upper Currituck Sound near Corolla in 

North Carolina, and Back Bay near Back Bay in Virginia. The 

hydrologic data included water elevation and velocity, and 

discharge. The water-quality data included discrete samples 

and continuous measurements of water temperature, specific 

conductance, dissolved oxygen, pH, turbidity, and chlorophyll 

a. The hydrologic and water-quality data collected for this 

study were quality assured by the U.S. Geological Survey and 

stored in the National Water Information System database. 

The data collected for this project are being used 

to develop an unsteady multidimensional hydrodynamic 

and water-quality model of Currituck Sound by the U.S. 

Army Corps of Engineers. The purpose of this model is to 

provide the basis for planning and the development of bestmanagement practices and restoration projects for Currituck 

Sound and its tributaries.

Introduction

Ecological conditions in and around Currituck Sound in 

northeastern North Carolina and southeastern Virginia have 

changed noticeably since at least the 1980s. Fish-population 

surveys have indicated a decrease in freshwater species and an 

increase in estuarine species. These changes are attributed to 

an increase in salinity in the sound (Southwick and Norman, 

1991). It is further hypothesized (U.S. Army Corps of Engineers, 2001) that the change in the salinity regime is associated 

with a substantial decline in submerged aquatic vegetation 

(SAV), although other factors may be responsible for the SAV 

declines. Beds of SAV provide food for migratory waterfowl, 

in addition to spawning and nursery habitats for fish species. 

A decline in SAV beds also contributes to a decline in water 

quality in that a decrease in SAV root systems and underwater 

biomass allows increased resuspension of fine sediments and 

associated nutrients during wind events (U.S. Army Corps of 

Engineers, 2001). 

Changes in salinity in Currituck Sound could be associated with droughts, ocean overwash, previous pumping of 

sea water into Back Bay, reduction of freshwater inflows, 

and transport of high-salinity waters between the sound and 

Chesapeake Bay to the north and the sound and Albemarle 

Sound to the south during wind events and tidal fluctuations 

(fig. 1; U.S. Army Corps of Engineers, 2001). Great Bridge 

Lock at the western end of Albemarle and Chesapeake Canal 

and 21 river miles (RMs) north of the Virginia and North 

Carolina State line prevents continuous inflow of high-salinity 

water from Elizabeth River into the canal and, thus, into 

Currituck Sound (fig. 1). Data collected during 1998–99 

indicate, however, that Elizabeth River may be a source of salt 

to Currituck Sound (Caldwell, 2001). About 14 RMs south of 

the State line, the Atlantic Intracoastal Waterway (AIWW) is 

routed through a land cut near Coinjock to the head of North 

River (fig. 1), where the AIWW continues south through 

North River to Albemarle Sound, another potential source of 

high-salinity water to Currituck Sound. 

No major point-source dischargers are in the Currituck 

Sound basin (North Carolina Department of Environment 

and Natural Resources, 2002). Nonpoint-source drainage to 

Tull Creek was identified in 1992–93 as the primary source 

of phosphorus and nitrogen to Currituck Sound. At that time, 

Back Bay was considered to be the second greatest source 

of nitrogen to Currituck Sound. In addition, Northwest River 

and North Landing River contribute high concentrations of 

phosphorus to the sound (North Carolina Division of Environment, Health, and Natural Resources, 1994). Jean Guite Creek, 

which flows to the north on the southeast side of the sound 

Documentation of Data Collection in Currituck Sound, 

North Carolina and Virginia, 2006–2007

By Jason M. Fine
2 Documentation of Data Collection in Currituck Sound, North Carolina and Virginia, 2006–2007

Figure 1. Locations of Currituck Sound and hydrologic and water-quality data-collection sites in North Carolina and Virginia, 2006–2007.

Base from digital files of:

U.S. Department of Commerce, Bureau of Census,

 1990 Precensus TIGER/Line Files-Political boundaries, 1991

Environmental Protection Agency, River File 3

U.S. Geological Survey, 1:100,000 scale

North American Datum of 1927 

Hell Point

Creek

Muddy

Creek

Beggars

Bridge

Creek

Nawney

Creek

Devil

Creek

Oakum

Creek

Milldam

Creek

Walnut Creek

Blackwater

 Creek

West

Neck

Creek

London

Bridge

Creek

Tull

Creek

Barco Corolla

Atlantic

Intracoastal

Waterway

Study site and site number 6

EXPLANATION

Jean Guite

Creek

24

14/15

6

23

5

4

21

20

7

Figure 1. Locations of Currituck Sound and hydrologic and water-quality data collection sites in

 North Carolina and Virginia, 2006-2007.
Introduction 3

(east of site 24, fig. 1), drains Southern Shores and parts of 

Kitty Hawk, and also may be a source of some nitrogen inputs 

to the sound. 

In 2001, the U.S. Army Corps of Engineers (USACE) 

conducted a reconnaissance study of Currituck Sound under 

Section 905(b) of the Water Resources Development Act of 

1986. The purpose of the study was “to determine whether 

planning for the improvement of water quality, environmental 

restoration and protection, and related purposes for Currituck 

Sound should proceed further” (U.S. Army Corps of Engineers, 2001). Among other things, one of the conclusions from 

the study was that Currituck Sound is a “threatened resource,” 

and that a hydrodynamic model was needed to evaluate the 

water and salt balance in the sound. Federal, State, and local 

government agencies subsequently concluded that a waterquality model, coupled with the hydrodynamic model, was 

needed to “assess the effect of management strategies on the 

sound’s water chemistry, quality, and resource viability.” Data 

collection to support model development and testing also was 

recommended. 

In 2005, a team of scientists was assembled to begin 

an investigation of the hydrologic and water-quality 

characteristics of Currituck Sound and its major tributaries. 

The objectives of the investigation were to document waterquality trends in the sound and collect the data needed for the 

development of the coupled hydrodynamic and water-quality 

model. The project partners for the study included the Division 

of Water Resources (DWR) of the North Carolina Department 

of Environment and Natural Resources, which funded much 

of the hydrologic and water-quality data collection and 

provided project oversight; Elizabeth City State University 

(ECSU), North Carolina National Estuarine Research Reserve 

(NERR), and the U.S. Fish and Wildlife Service (FWS), all 

of which were responsible for water-quality data collection; 

the USACE, which was charged in the development of an 

unsteady, multidimensional hydrodynamic and water-quality 

model of the sound and provided overall project management; 

The University of North Carolina at Chapel Hill Institute of 

Marine Sciences (IMS), which provided laboratory analyses 

of water-quality samples; and the U.S. Geological Survey 

(USGS), which provided for hydrologic data collection, 

water-quality data-collection oversight and quality assurance, 

data processing and storage, and watershed modeling.

Purpose and Scope

The purpose of this report is to document the datacollection efforts of the USGS and its project partners in and 

around Currituck Sound during 2006 and 2007. Data were 

collected at nine locations in the study area from January 

2006 to September 2007 and include more-or-less continuous 

measurements of water elevation, velocity, discharge, water 

temperature, specific conductance, dissolved oxygen, pH, 

turbidity, and chlorophyll a at a subset of the nine sites. 

Water-quality samples also were collected at selected sites in 

the sound.

This report describes the sites and the methods used for 

data collection, quality assurance, and archiving. The data 

collected for this project are being used by the USACE in the 

development of an unsteady, multidimensional hydrodynamic 

and water-quality model of the sound. 

Study Area

Currituck Sound is a 97,852-acre (153 square mile (mi2)) 

oligohaline estuary in the northeastern part of the Coastal 

Plain Physiographic Province of North Carolina (fig. 1). Back 

Bay, which is north of Currituck Sound, covers an area of 

about 26,000 acres (41 mi2) in the southeastern part of the 

Coastal Plain Physiographic Province of Virginia (fig. 1). The 

drainage area of the entire Currituck Sound is estimated to be 

733 mi2

, of which almost one-third is open water. Most of the 

land that drains to Currituck Sound is in the cities of Virginia 

Beach and Chesapeake, Virginia, and in northwest Currituck 

County in North Carolina. Because the flow in several canals 

that connect Currituck Sound to Chesapeake Bay can move 

northward or southward and because of the low topographic 

relief in the basin, the exact identification of the drainage area 

of Currituck Sound is uncertain. 

The climate of the study area is temperate and oceanic. 

The average annual precipitation is about 45 inches (in.), and 

monthly totals typically are greatest during July and August 

(Norman, 1991). Flood-producing rainfalls and high winds 

associated with hurricanes or tropical storms and(or) convective thunderstorms generally occur during the summer or fall. 

In addition, nor’easters are storms that generate strong winds, 

heavy rainfalls, and high water elevations or flooding and 

generally occur during fall and winter months. 

Three major tributaries supply most of the freshwater 

to Currituck Sound—North Landing River, Northwest River, 

and Tull Creek (fig. 1). Northwest River and Tull Creek drain 

mostly agricultural lands and have drainage areas of 196 mi2 

and 52 mi2, respectively. The drainage area of North Landing 

River at the Virginia-North Carolina State line is about 

117 mi2. The North Landing River is channelized over its 

entire length, as a part of the AIWW, and joins the Albemarle 

and Chesapeake Canal about 12 RMs north of the State line. 

Great Bridge Lock, is at the western end of the Albemarle and 

Chesapeake Canal and about 21 RMs from the Virginia-North 

Carolina State line (fig. 1).

From Great Bridge Lock, the AIWW extends east 

through the Albemarle and Chesapeake Canal and south 

through the North Landing River and into Currituck Sound. 

About 14 RMs south of the Virginia-North Carolina State line, 

the AIWW is routed through a land cut near Coinjock to the 

confluence of North River where the AIWW continues south 

through the North River, parallel to Currituck Sound, to the 

confluence with Albemarle Sound (fig. 1).
4 Documentation of Data Collection in Currituck Sound, North Carolina and Virginia, 2006–2007

Data Collection

Data for this study were collected at nine sites in and 

around Currituck Sound (fig. 1; table 1). Data collection began 

in January 2006 and continued through September 2007. A 

few gaps occurred in the continuous-data record because of 

instrumentation failure or fouling of sensors (fig. 2). Waterquality samples were collected biweekly during typically 

warmer months (April through October) and monthly during 

typically colder months (November through March). This 

section describes the type of data collected, the methods used 

to collect the data, quality-assurance procedures, and data 

archival. 

Water Elevation, Water Velocity, and Discharge

Water elevation and velocity were measured at sites 4, 

5, 6, 7, 20, and 24 using acoustic Doppler velocity meters 

(ADVMs; fig. 1). Data were logged at 15-minute intervals to 

a data-collection platform and transmitted by satellite to the 

USGS National Water Information System (NWIS) database. 

Water-elevation (stage) data were collected by a pressure 

transducer in the ADVM using techniques described in Freeman and others (2004). The data were recorded to an accuracy 

of 0.01 foot (ft) and were referenced to North American 

Vertical Datum of 1988 (NAVD 88) using a differential global 

positioning system or nearby benchmarks. 

The ADVM measures water velocity by the way of 

transducers that send and receive acoustic pulses. An acoustic 

pulse of a known frequency is sent into the water column 

along an acoustic beam. A portion of the acoustic pulse is 

reflected back to the transducer at a frequency that has been 

shifted because of the Doppler effect. An index velocity is 

determined by the change in the acoustic frequency and the 

geometric configuration of the transducers (SonTek Corporation, 2000). Details on the theory and operation of the ADVM 

system were documented by Morlock and others (2002) and 

Ruhl and Simpson (2005). 

River discharge can be computed as

(1)

where,

 Q is discharge, in cubic feet per second;

 V is mean velocity at a specified channel cross 

section, in feet per second; and

 A is channel area for a specified cross section, 

in square feet.

Channel area for a river can be determined by surveying 

a cross section. To account for the change in cross sectional 

area over a range of stages, a stage-area rating is developed 

by computing the channel area for a range of river stages. 

To compute cross-sectional mean velocities from ADVMmeasured velocities, the relation between mean channel 

velocity and ADVM-measured velocities must be established. 

The method used to relate mean velocity and ADVMmeasured velocity is referred to as the index-velocity method. 

The ADVM measures velocity in a part of the stream, and 

the measured velocity is used to estimate, or index, the mean 

channel velocity. 

To establish the relations between mean channel velocity 

and ADVM velocity, discharge measurements were made near 

the gaging stations with an acoustic Doppler current profiler 

while the ADVM’s were measuring velocity. Mean velocities 

were derived for each individual discharge measurement by 

dividing the measured discharge by the channel area computed 

from the stage-area ratings. Each discharge measurement 

Q VA = ,

Table 1. Description of data-collection sites in and around Currituck Sound in North Carolina and Virginia, 2006–2007.

[USGS, U.S. Geological Survey; ~, approximately]

Site 

number 

(fig. 1)

USGS 

station 

number

Site name Latitude Longitude

Mean 

channel 

width 

(feet)

Mean 

water 

depth 

(feet)

4 02043410 Northwest River above mouth near Moyock, NC 36°30'44" 76°05'12" 477 8.2 

5 02043415 Tull Creek at SR 1222 near Currituck, NC 36°29'47" 76°05'03" 219 7.6 

6 0204343500 Intracoastal Waterway at Coinjock, NC 36°20'34" 75°57'15" 181 19.1 

7 02043120 Albemarle and Chesapeake Canal near Princess Anne, VA 36°43'04" 76°06'02" 226 10.1 

14/15 02043460 Currituck Sound off Dews Island near Jarvisburg, NC 36°12'39" 75°48'20" ~21,000 4.9a

20 02043270 North Landing River near Creeds, VA 36°36'58" 76°02'57" 422 10.6 

21 02043016 Back Bay below Ragged Island near Back Bay, VA 36°37'03" 75°56'31" ~23,000 6.9a

23 02043430 Upper Currituck Sound near Corolla, NC 36°23'43" 75°50'33" ~23,500 3.0a

24 0204347500 Currituck Sound at US 158 nr Point Harbor, NC 36°05'12" 75°46'06" ~14,000 9.0a

a

Water depth at the water-quality monitoring site.
Data Collection 5

Figure 2. Summary of continuous data collected at study sites in and around Currituck Sound, North Carolina and Virginia, 2006–2007.

JAN. FEB. DEC.NOV.OCT.SEPT.AUG.JULYJUNEMAYAPR.MAR.

Water Elevation

Water Elevation

Water Elevation

Water Elevation

Discharge

Velocity

Temperature

Salinity

Dissolved Oxygen

pH

Turbidity

Chlorophyll

Discharge

Velocity

Temperature

Salinity

Dissolved Oxygen

pH

Turbidity

Chlorophyll

Discharge

Velocity

Temperature

Salinity

Dissolved Oxygen

pH

Turbidity

Chlorophyll

2006

JAN. FEB. DEC.NOV.OCT.SEPT.AUG.JULYJUNEMAYAPR.MAR.

2007

Discharge

Velocity

SITES 14/15

Temperature

Salinity

Dissolved Oxygen

pH

Turbidity

Chlorophyll

No Data

Partial Data

Complete Record

SITE 6 SITE 7 SITE 5 SITE 4

Figure 2. Summary of continuous data collected at study sites in and around Currituck Sound,

 North Carolina and Virginia, 2006-2007.
6 Documentation of Data Collection in Currituck Sound, North Carolina and Virginia, 2006–2007

Figure 2 (Continued). Summary of continuous data collected at study sites in and around Currituck Sound, North Carolina and Virginia, 

2006–2007.

JAN. FEB. DEC.NOV.OCT.SEPT.AUG.JULYJUNEMAYAPR.MAR.

2006

JAN. FEB. DEC.NOV.OCT.SEPT.AUG.JULYJUNEMAYAPR.MAR.

2007

No Data

Partial Data

Complete Record

SITE 23 SITE 24 SITE 21 SITE 20

Temperature

Salinity

Dissolved Oxygen

pH

Turbidity

Water Elevation

Water Elevation

Discharge

Velocity

Temperature

Salinity

Dissolved Oxygen

pH

Turbidity

Chlorophyll

Temperature

Salinity

Dissolved Oxygen

pH

Turbidity

Chlorophyll

Velocity

Temperature

Salinity

Dissolved Oxygen

pH

Turbidity

Figure 2 continued. Summary of continuous data collected at study sites in and around 

 Currituck Sound, North Carolina and Virginia, 2006-2007.
Data Collection 7

provided a computed mean channel velocity and an average 

ADVM velocity. These data then were used to develop an 

index-velocity rating at each site to compute mean channel 

velocities from ADVM velocities. Instantaneous discharge was 

computed using index velocity ratings at sites 4, 5, 6, 7, and 

20. 

Because of the channel width of Currituck Sound at 

site 24, the index-velocity method was not used to calculate 

discharge data. However, water velocity was measured at 

this site at 0.5-meter intervals through the water column to 

document velocities at the mouth of the sound.

Continuous Water-Quality Data

Continuous water-quality data were collected and 

logged at sites 4, 5, 6, 14/15, 20, 21, 23, and 24 using YSI 

multi-parameter water-quality sondes (table 2; YSI Inc., 

2006). Water temperature, specific conductance, dissolved 

oxygen, ph, and turbidity was measured at a single depth in 

the water column at each site. Additionally, chlorophyll a

was measured at sites 4, 5, 6, 14/15, and 20. Each site was 

visited periodically by the project partners (biweekly from 

April through October and monthly from November through 

March) to exchange the dirty sonde with a newly cleaned and 

calibrated sonde and to retrieve the data. During these site 

visits, the two sondes (the one being replaced and the replacement sonde) were placed side by side in a bucket of in-situ 

water to get comparison readings between the dirty sonde and 

the clean, calibrated sonde. The clean, calibrated sonde then 

was used to measure a vertical profile of the water column 

to ensure that the sensor measurements were representative 

of the local waterbody before deploying the sonde at the site 

to begin recording data. The dirty sonde was returned to the 

laboratory for post-calibration processing and downloading the 

data. The post-calibration processing entailed immersing the 

dirty sensors in known standards and recording the readings. 

These readings in conjunction with the values obtained in the 

side-by-side comparison in the field were used to determine 

corrections to apply to the data. All data then were sent to the 

USGS for processing and storage in the NWIS database, and 

the sondes were cleaned, calibrated, and prepared for the next 

deployment. These methods, which were used when servicing 

the water-quality monitors and processing the data, were 

modified from methods documented by Wagner and others 

(2006).

All calibrations were done in a stable laboratory environment or similar condition. For water temperature, no calibrations are necessary, but the temperature sensor was compared 

during each calibration to another thermometer to ensure the 

accuracy of the sensor. The temperature probes have a range 

of -5 degrees Celsius (oC) to 45 oC and an accuracy of plus or 

minus (+/-) 0.15 oC. The specific conductance probes were 

calibrated to two known standards and checked against a 

third standard, which bracketed the expected environmental 

conditions at the deployment site. Specific conductance is 

the electrical conductivity of water, expressed in units of 

microsiemens per centimeter at 25 oC (μS/cm at 25 oC). The 

specific conductance probes have a range of 0 to 100,000 

μS/cm at 25 oC and an accuracy of +/- 0.5 percent of the 

reading. Specific conductance was converted to salinity in the 

database by using the algorithm given in Miller and others 

(1988). Dissolved-oxygen sensors were calibrated by using the 

Table 2. Description of data collected in and around Currituck Sound in North Carolina and Virginia, 2006–2007.

[NAVD 88, North American Vertical Datum of 1988; IMS, The University of North Carolina at Chapel Hill Institute of Marine Sciences; NWQL, USGS 

National Water Quality Laboratory; USGS, U.S. Geological Survey; ECSU, Elizabeth City State University; —, no data collected; na, not applicable; 

FWS, U.S. Fish and Wildlife Service; NEER, North Carolina National Estuarine Research Reserve]

Site number 

(fig. 1)

Project partner responsible for data collection Continuous 

water-quality 

monitoring 

probe location 

(feet above 

channel bottom)

Number of 

water-quality 

samples 

analyzed 

by IMS

Number of 

water-quality 

samples 

analyzed 

by NWQL

Continuous 

discharge

Continuous water 

elevation referenced 

to NAVD 88

Discrete 

water-quality 

samples

Continuous 

water-quality 

monitoring 

4 USGS USGS ECSU ECSU 3.0 16 2

5 USGS USGS ECSU ECSU 3.0 16 2

6 USGS USGS ECSU ECSU 5.5 16 1

7 USGS USGS USGS — na 7 3

14/15 — — ECSU ECSU 1.0 16 2

20 USGS USGS ECSU ECSU 3.0 16 2

21 — — USGS FWS 3.0 8 3

23 — — NEER NEER 1.0 18 3

24 — USGS NEER NEER 3.0 19 3
8 Documentation of Data Collection in Currituck Sound, North Carolina and Virginia, 2006–2007

100 percent air-saturation method and checked for range by 

using a zero dissolved-oxygen standard. The dissolved-oxygen 

probes have a range of 0 to 20 milligrams per liter (mg/L) 

with an accuracy of +/- 2 percent of the reading or 0.2 mg/L, 

whichever is greater. The pH probes were calibrated by using 

two known standards that bracketed the expected environmental conditions at the deployment site. The pH probes have a 

range of 0 to 14 units and an accuracy of 0.01 unit. The turbidity probes were calibrated to two standards—a zero standard 

(de-ionized water) and a known standard. The turbidity probe 

has a range of 0 to 1,000 Formazin Nephelometric Units 

(FNU) and an accuracy of 0.1 FNU. The chlorophyll sensors 

were calibrated by using two standards—a zero standard 

(de-ionized water) and a known rhodamine-B dye solution. 

The chlorophyll sensors have a range of 0 to 400 micrograms 

per liter (μg/L) with no specified accuracy. 

Water-Quality Samples

Water samples were collected by the project partners at 

all sites (table 2) beginning in July 2006 and ending when 

the continuous monitors were removed. Samples were depth 

integrated to a depth that was twice the secchi depth by using 

a single-bottle weighted sampler. Barometric pressure and 

secchi depth were measured and recorded during sample 

collection. Water temperature, specific conductance, dissolved 

oxygen, pH, and turbidity were measured and recorded at 

the secchi depth using a calibrated water-quality monitor at 

the time of the sample collection. The samples were chilled, 

filtered when necessary, processed, and shipped to The 

University of North Carolina at Chapel Hill Institute of Marine 

Sciences analytical laboratory for analysis. The samples were 

collected and processed using techniques described in the 

USGS national field manual for the collection of water-quality 

samples (U.S. Geological Survey, continually updated).

Water-quality samples were analyzed for total suspended 

solids, total carbon, dissolved organic carbon, dissolved 

silica, chlorophyll a, total particulate nitrogen, total dissolved 

nitrogen, dissolved nitrite plus nitrate, dissolved ammonia, and 

dissolved orthophosphate. The IMS laboratory methods used 

for each analysis are listed in table 3. All sample results were 

reported to the USGS and stored in the NWIS database.

Quality Assurance and Data Archival

Water elevation, velocity, and discharge data were 

collected and quality assured by the USGS using methods 

described in Rantz and others (1982), Rantz (1982), and 

Ruhl and Simpson (2005). To ensure a uniform water-quality 

dataset, the USGS trained the ECSU, NERR, and FWS project 

partners in data collection and documentation techniques for 

the collection of continuous water-quality data and waterquality sampling in accordance with methods described in 

Wagner and others (2006), as modified for this study, and the 

U.S. Geological Survey (continually updated). The USGS 

project personnel periodically accompanied project partners 

to the data-collection sites to provide additional training and 

assistance and to collect quality-assurance samples.

The USGS collected one to three duplicate water-quality 

samples at each site for analysis at the USGS National Water 

Quality Laboratory (NWQL) for comparison with results of 

the water-quality analyses conducted at the IMS laboratory. In 

Table 3. Analytical methods used to analyze the water-quality samples collected in and around Currituck Sound in North Carolina 

and Virginia, 2006–2007.

[IMS, The University of North Carolina at Chapel Hill Institute of Marine Sciences; NWQL, U.S. Geological Survey National Water Quality Laboratory; 

SM, standard methods; USGS, U.S. Geological Survey; EPA, U.S Environmental Protection Agency]

Analyte IMS analytical method and citation NWQL analytical method and citation

total suspended solids SM 2540 D, Eaton and others (2005) USGS I-3765-89, Fishman and Friedman (1989)

total carbon EPA 440.0, U.S. Environmental Protection 

Agency (1997)

EPA 440.0, U.S. Environmental Protection Agency (1997)

dissolved organic carbon EPA 415.3, U.S. Environmental Protection 

Agency (2005)

USGS O-1120-92, Brenton and Arnett (1993)

dissolved silica SM 4500-SiO2 F, Eaton and others (2005) USGS I-2700-89, Fishman and Friedman (1989)

chlorophyll a EPA 445.0, Arar and Collins (1997) EPA 445.0, Arar and Collins (1997)

total particulate nitrogen EPA 440.0, U.S. Environmental Protection 

Agency (1997)

EPA 440.0, U.S. Environmental Protection Agency (1997)

total dissolved nitrogen calculated (no citation) calculated (no citation)

dissolved nitrite + nitrate SM 4500-NO3 I, Eaton and others (2005) USGS I-2546-91, Fishman (1993)

dissolved ammonia SM 4500-NH3 H, Eaton and others (2005) USGS I-2525-89, USGS I-2522-90, Fishman (1993)

dissolved orthophosphate SM 4500-P G, Eaton and others (2005) USGS I-2601-90 , USGS I-2606-89, Fishman (1993)
Summary 9

addition, equipment blanks were collected by the USGS and 

project partners and analyzed at the IMS laboratory and the 

NWQL for quality assurance.

All data were processed by USGS personnel and 

published in the USGS annual water-resources data report for 

North Carolina (U.S. Geological Survey, 2007, 2008). Water 

elevation, velocity, discharge, and water-quality data collected 

by the USGS and the project partners during this study are 

stored in the USGS NWIS database. The continuous data 

available for each site and the number of complete days in the 

continuous record are presented in figure 2 and table 4. All 

project data can be obtained through the NWIS web interface 

at http://waterdata.usgs.gov/nc/nwis or in the USGS annual 

water-resources data report (U.S. Geological Survey, 2007, 

2008).

Summary

Because of changes in ecological conditions in and 

around Currituck Sound in northeastern North Carolina and 

southeastern Virginia, a team of scientists from multiple 

project partners was assembled to conduct an investigation 

of the hydrologic and water-quality characteristics of the 

sound and its major tributaries. As part of this investigation, 

a comprehensive set of hydrologic and water-quality data 

were collected in and around Currituck Sound during January 

2006–September 2007. The data-collection network was 

designed to provide information needed to develop and apply 

a hydrodynamic and water-quality model to Currituck Sound 

to evaluate the effects of various management scenarios. 

The data were collected at nine sites and include continuous 

discharge, water elevation and velocity, and physical measures 

of water-quality conditions; discrete water samples were 

collected for analysis. The project partners who participated 

in the data collection included Elizabeth City State University, 

North Carolina National Estuarine Research Reserve, and 

U.S. Fish and Wildlife Service, which were responsible 

for water-quality data collection; The University of North 

Carolina at Chapel Hill Institute of Marine Sciences (IMS), 

which provided laboratory analyses of water-quality samples; 

and the U.S. Geological Survey, which was responsible for 

hydrologic data collection, water-quality data-collection 

oversight and quality assurance, and data processing. The U.S. 

Geological Survey provided training and quality assurance for 

the data-collection activities, processed the data, and archived 

all data in the USGS NWIS database.

Acknowledgments

The USGS would like to thank John Morris, John 

Sutherland, and Darren England of the North Carolina 

Division of Water Resources; Mitch Hall and John Hazelton 

of the U.S. Army Corps of Engineers; Amber Eure, Elizabeth 

Noble, and Kathleen Fisher of Elizabeth City State University; 

John Fear, Ann Wunderly, and Susan Dworsky of the North 

Carolina National Estuarine Research Reserve; John Gallegos, 

Sterling Valentine, and Sharon Tatem of the U.S. Fish and 

Wildlife Service; and Hans Paerl, Ben Perlis, and Karen 

Rossingol of the University of North Carolina at Chapel Hill 

Institute of Marine Sciences for the unique cooperation that 

occurred during this project. Also, appreciation is extended 

to the private property owners and the U.S. Army Corps of 

Engineers for allowing access to their property during this 

data-collection effort. 

Table 4. Number of complete days of continuous record data collected in and around Currituck Sound in North Carolina and Virginia 

from January 2006 through September 2007.

[—, data not collected ]

Site 

number 

(fig. 1) 

Water 

elevation 

Water 

velocity 

Stream 

discharge 

Water 

temperature 

Specific 

conductance Salinitya Dissolved 

oxygen pH Turbidity Chlorophyll a

4 553 557 558 428 428 428 425 428 413 405

5 558 558 558 482 482 482 445 419 373 410

6 617 615 616 487 487 487 385 487 425 429

7 560 560 560 — — — — — — —

14/15 — — — 401 401 401 365 368 377 342

20 608 610 611 443 443 443 431 426 307 443

21 — — — 414 414 414 385 410 323 —

23 — — — 450 450 450 431 450 411 —

24 559 559 — 505 504 504 479 496 468 —

a

Calculated from specific conductance data (Miller and others, 1988).
10 Documentation of Data Collection in Currituck Sound, North Carolina and Virginia, 2006–2007

References

Arar, E J., and Collins G.B., 1997, U.S. Environmental 

Protection Agency Method 445.0, In vitro determination of 

chlorophyll a and pheophytin a in marine and freshwater 

algae by fluorescence, Revision 1.2: Cincinnati, OH, U.S. 

Environmental Protection Agency, National Exposure 

Research Laboratory, Office of Research and Development.

Brenton, R.W., and Arnett, T.L., 1993, Methods of analysis 

by the U.S. Geological Survey National Water Quality 

Laboratory—Determination of dissolved organic carbon by 

UV-promoted persulfate oxidation and infrared spectrometry: U.S. Geological Survey Open-File Report 92–480, 

12 p.

Caldwell, W.S., 2001, Hydrologic and salinity characteristics 

of Currituck Sound and selected tributaries in North 

Carolina and Virginia, 1998–99: U.S. Geological Survey 

Water-Resources Investigations Report 01–4097, 36 p.

Eaton, A.D., Clesceri, L.S., Rice, E.W., and Greenburg, A.E., 

eds., 2005, Standard methods for the examination of water 

and wastewater (21st ed.): Washington, DC, American 

Public Health Association, variously paged.

Fishman, M.J., ed., 1993, Methods of analysis by the U.S. 

Geological Survey National Water Quality Laboratory—

Determination of inorganic and organic constituents in 

water and fluvial sediments: U.S. Geological Survey 

Open-File Report 93–125, 217 p.

Fishman, M.J., and Friedman, L.C., 1989, Methods for 

determination of inorganic substances in water and fluvial 

sediments: U.S. Geological Survey Techniques of WaterResources Investigations, book 5, chap. A1, 545 p.

Freeman, L.A., Carpenter, M.C., Rosenberry, D.O., Rousseau, 

J.P., Unger, R., and McLean, J.S., 2004, Use of submersible 

pressure transducers in water-resources investigations: 

U.S. Geological Survey Techniques of Water-Resources 

Investigations, book 8, chap. A3, 65 p.; accessed February 7, 2008, at http://pubs.usgs.gov/twri/twri8a3/pdf/

twri8-a3.pdf.

Miller, R.L., Bradford, W.L., and Peters, N.E., 1988, Specific 

conductance—theoretical considerations and applications to 

analytical quality control: U.S. Geological Supply WaterSupply Paper 2311, 16 p.

 Morlock, S.E., Nguyen, H.T., and Ross, J.H., 2002, Feasibility of acoustic Doppler velocity meters for production of 

discharge records from U.S. Geological Survey streamflowgaging stations: U.S. Geological Survey Water-Resources 

Investigations Report 01–4157, 56 p.

Norman, M.D., 1991, Description of study area, in Marshall, 

H.G. and Norman, M.D., eds., 1991, Proceedings of the 

Back Bay Ecological Symposium, Norfolk, VA, Old 

Dominion University, p. 4–7.

North Carolina Department of Environment and Natural 

Resources, 2002, Basinwide assessment report—Chowan 

and Pasquotank River basins: Raleigh, Division of Water 

Quality, Water Quality Section, 131 p.

North Carolina Division of Environment, Health, and Natural 

Resources, 1994, Currituck Sound outstanding resource 

waters evaluation: Raleigh, Division of Environmental 

Management, Water Quality Section, 33 p.

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

streamflow—Volume 2, Computation of stage and discharge: U.S. Geological Survey Water-Supply Paper 2175, 

p. 285–631.

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

of streamflow—Volume 1, Measurement of stage and 

discharge: U.S. Geological Survey Water-Supply Paper 

2175, 284 p.

Ruhl, C.A., and Simpson, M.R., 2005, Computation of 

discharge using the index-velocity method in tidally affected 

areas: U.S. Geological Survey Scientific Investigations 

Report 2005–5004, 31 p.

SonTek Corporation, 2000, SonTek ADVM-series instruments 

technical documentation: San Diego, CA, 77 p.

Southwick, Ronald, and Norman, M.D., 1991, Impact of 

salinity changes on fish populations in Back Bay, Virginia, 

1950–1989, in Marshall, H.G., and Norman, M.D., eds., 

1991, Proceedings of the Back Bay Ecological Symposium: 

Norfolk, VA, Old Dominion University, p. 138–147.

U.S. Army Corps of Engineers, 2001, Reconnaissance 

report—Currituck Sound, North Carolina: Wilmington, NC, 

U.S. Army Corps of Engineers, Wilmington District, 15 p.

U.S. Environmental Protection Agency, 1997, Determination 

of carbon and nitrogen in sediments and particulates of 

estuarine/coastal waters using elemental analysis, Revision 

1.4, September 1997: U.S. Environmental Protection 

Agency, National Exposure Research Laboratory, Office of 

Research and Development, 10 p.

U.S. Environmental Protection Agency 2005, Determination 

of total organic carbon and specific UV absorbance at 

254 nm in source water and drinking water, Revision 1.1, 

February 2005: U.S. Environmental Protection Agency, 

National Exposure Research Laboratory, Office of Research 

and Development, 56 p.
References 11

U.S. Geological Survey, Continually updated, National 

field manual for the collection of water-quality data: 

U.S. Geological Survey Techniques of Water-Resources 

Investigations, book 9, chaps A1–A9; accessed January 23, 

2008, at http://water.usgs.gov/owq/FieldManual/.

U.S. Geological Survey, 2007, Water-resources data for the 

United States, water year 2006, U.S. Geological Survey 

Water-Data Report WDR–US–2006, accessed January 23, 

2008, at http://wdr.water.usgs.gov/.

U.S. Geological Survey, 2008, Water-resources data for the 

United States, water year 2007, U.S. Geological Survey 

Water-Data Report WDR–US–2007, accessed January 23, 

2008, at http://wdr.water.usgs.gov/.

Wagner, R.J., Boulger, R.W., Jr., Oblinger, C.J., and Smith, 

B.A., 2006, Guidelines and standard procedures for 

continuous water-quality monitors—Station operation, 

record computation, and data reporting: U.S. Geological 

Survey Techniques and Methods 1–3, 51 p. + 8 attachments; 

accessed January 23, 2008, at http://pubs.usgs.gov/tm/2006/

tm1D3.

YSI Inc., 2006, 6–series environment monitoring systems 

manual, Revision D: Yellow Springs, OH, YSI Inc., 372 p.
Fine—Documentation of Data Collection in Currituck Sound, North Carolina and Virginia, 2006–2007—Open-File Report 2008–1147