Water Quality in the

Albemarle-Pamlico

Drainage Basin

North Carolina and Virginia, 1992–95

U.S. Department of the Interior

U.S. Geological Survey Circular 1157

science for a changing world
FOR ADDITIONAL INFORMATION ON THE

NATIONAL WATER-QUALITY ASSESSMENT (NAWQA) PROGRAM:

A COORDINATED EFFORT

Chief, NAWQA Program

U.S. Geological Survey

Water Resources Division

12201 Sunrise Valley Drive, Mail Stop 4

Reston, VA 20192

Coordination among agencies and organizations is an integral part of the NAWQA Program. We thank the follo

agencies and organizations who contributed data used in this report.

Federal Agencies

 National Marine Fisheries Service

 National Oceanic and Atmospheric Administration

 National Park Service

 National Resources Conservation Service

 U.S. Army Corps of Engineers

 U.S. Department of Agriculture

 U.S. Environmental Protection Agency

 U.S. Fish and Wildlife Service

State Agencies

 North Carolina Department of Agriculture

 North Carolina Center for Geographic Information and Analysis

 North Carolina Department of Environment and Natural Resources

 North Carolina Division of Water Quality

 North Carolina Division of Water Resources

 Virginia Department of Agriculture and Consumer Services

 Virginia Department of Conservation and Recreation

 Virginia Department of Environmental Quality

Local Agencies

 Triangle J Council of Governments

 City of Durham, North Carolina

 City of Kinston, North Carolina

 City of Raleigh, North Carolina

 Franklin County Agricultural Extension

 Town of Aurora, North Carolina

 Town of Franklin, North Carolina

 City of Roanoke, Virginia

 City of Virginia Beach, Virginia

 Hampton Roads Planning Agency

Albemarle-Pamlico Drainage

 Study Unit, contact:

District Chief

U.S. Geological Survey

3916 Sunset Ridge Road

Raleigh, NC 27607

Information on the NAWQA Program is also available on the Internet via the World Wide Web.

Albemarle-Pamlico Drainage Study Unit’s Home Page: http://sgi1dncrlg.er.usgs.gov/albe-html/ALBEpage.html

NAWQA Home Page: http://wwwrvares.er.usgs.gov/nawqa/nawqa_home.html

Universities

 Duke University

 Ferrum College

 North Carolina State University

 University of North Carolina

 Virginia Commonwealth University

 Virginia Polytechnic Institute and State Univers

Private Organizations

 Neuse River Foundation

 North Carolina Environmental Defense Fund

 Research Triangle Institute

 Union Camp Corporation

 Weyerhauser Corporation

Special thanks to:

 All the farmers and landowners who kindly gran

permission to install wells and collect data.

 Dr. Wendell Gilliam, North Carolina State Unive

 Dr. Greg Jennings, North Carolina State Unive

Agricultural Extension

 Mr. Kris Matson, North Carolina State Universit

 Dr. Ted Mew, North Carolina Division of Water 

 Ms. Elizabeth Morey, North Carolina Division o

Quality

 Mr. Hassell Thigpen, Farmer, Edgecombe Cou

North Carolina

 Dr. Henry Wade, North Carolina Department of

Agriculture

The following U.S. Geological Survey employee

contributions added substantively to the proj

Douglas J. Newcomb, Larry J. Puckett,

Stanley C. Skrobialowski, Janie B. Williams,

and Carlton D. Woods

Cover photograph: Neuse River at Cliffs of the Neuse State Park, North Carolina, during floodflow in 1996

Photographs in this report and on the front and back covers were taken by Douglas A. Harned, U.S. Geo

Survey.
U.S. GEOLOGICAL SURVEY CIRCULAR

Water Quality in the Albemarle-Pamlico

Drainage Basin, North Carolina and Virginia

1992–95

1157

By Timothy B. Spruill, Douglas A. Harned, Peter M. Ruhl,

Jo Leslie Eimers, Gerard McMahon, Kelly E. Smith,

David R. Galeone, and Michael D. Woodside

CONTENTS

The NAWQA Program ..................................

Summary of water-quality issues and

major findings..............................................

Environmental setting and hydrologic

conditions .....................................................

Major issues and findings..............................

Water-quality conditions in a

national context ...........................................

Study design and data collection..................

Summary of compound detections and

concentrations .............................................

References ........................................................

Glossary............................................................
The use of firm, trade, and brand names in this report is for identification purposes only and

does not constitute endorsement by the U.S. Government

Free on application to the

U.S. Geological Survey

Information Services

Box 25286 Federal Center

Denver, CO 80225

U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Thomas J. Casadevall, Acting Director

Library of Congress Cataloging-in-Publication Data

Water-quality assessment of the Albemarle-Pamlico drainage basin, North Carolina, and Virginia, 1992–95

/ by Timothy B. Spruill . . . [et al.].

p. cm.—(U.S. Geological Survey circular ; 1157)

Includes bibliographical references.

ISBN 0-607-89234-X

1. Water quality—North Carolina—Albemarle Sound Region. 2. Water quality—North Carolina—

Pamlico Sound Region. I. Spruill, T.B. II. Series.

TD224.N8W34 1998

363.739’42’09756—dc21 98-13016

CIP

1998
U.S. Geological Survey Circular 11

NATIONAL WATER-QUALITY ASSESSMENT PROGRAM

Began in 1991

Began in 1994

Began in 1997

Not scheduled yet

EXPLANATION

Knowledge of the quality of the Nation's streams and aquifers is important because

of the implications to human and aquatic health and because of the significant costs

associated with decisions involving land and water management, conservation, and

regulation. In 1991, the U.S. Congress appropriated funds for the U.S. Geological

Survey (USGS) to begin the National Water-Quality Assessment (NAWQA) Program

to help meet the continuing need for sound, scientific information on the areal extent

of the water-quality problems, how these problems are changing with time, and an

understanding of the effects of human actions and natural factors on water quality

conditions.

The NAWQA Program is assessing the water-quality conditions of more than 50 of

the Nation's largest river basins and aquifers, known as Study Units. Collectively,

these Study Units cover about one-half of the United States and include sources of

drinking water used by about 70 percent of the U.S. population. Comprehensive

assessments of about one-third of the Study Units are ongoing at a given time. Each

Study Unit is scheduled to be revisited every decade to evaluate changes in waterquality conditions. NAWQA assessments rely heavily on existing information

collected by the USGS and many other agencies as well as the use of nationally

consistent study designs and methods of sampling and analysis. Such consistency

simultaneously provides information about the status and trends in water-quality

conditions in a particular stream or aquifer and, more importantly, provides the basis

to make comparisons among watersheds and improve our understanding of the factors

that affect water-quality conditions regionally and nationally.

This report is intended to summarize major findings that emerged between 1992

and 1995 from the water-quality assessment of the Albemarle-Pamlico Drainage

Study Unit and to relate these findings to water-quality issues of regional and national

concern. The information is primarily intended for those who are involved in waterresource management. Indeed, this report addresses many of the concerns raised by

regulators, water-utility managers, industry representatives, and other scientists,

engineers, public officials, and members of stakeholder groups who provided advice

and input to the USGS during this NAWQA Study-Unit investigation. Yet, the

information contained here may also interest those who simply wish to know more

about the quality of water in the rivers and aquifers in the area where they live.

Robert M. Hirsch, Chief Hydrologist
2 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

SUMMARY OF WATER-QUALITY ISSUES AND MAJOR FINDINGS

NUTRIENTS IN STREAMS

• Of four river basins studied in the Albemarle-Pamlico

Drainage Basin—the Chowan, Roanoke, Tar, and

Neuse—highest nitrogen and phosphorus yields

occurred in the highly agricultural and urbanized Neuse

Basin; lowest nutrient yields occurred in streams of the

forested Chowan Basin (p. 7).

• Suspended-sediment, suspended-solids, and dissolvedsolids concentrations have decreased throughout the

Albemarle-Pamlico drainage system from 1980 to

1995. Decreasing concentrations of suspended solids in

the sounds and estuaries may result in clearer water and

deeper light penetration which, in turn, enhance

conditions for algal blooms in nutrient-enriched areas.

As a result, reduction of nutrients will be even more

important in controlling eutrophication (p. 15).

• A 50-percent reduction of summertime nitrogen and

phosphorus concentrations in the Neuse River and a

30-percent reduction of these same constituents in the

Tar River and Contentnea Creek would be required to

attain literature-based guidelines to reduce the

incidence of nuisance algal blooms and fishkills (p. 14).

• Permitted point sources of nitrogen and phosphorus

from municipal wastewater-treatment plants and

industry account for less than 6 percent of the nitrogen

source inputs and 16 percent of the phosphorus source

inputs in all basins. However, nutrients from these point

sources go directly into streams and may constitute

more than 40 percent of the instream nutrient load

(p. 6).

• Based on synoptic data collected in 1995, ground water

contributes significantly to instream phosphorus loads

of the Neuse River, Contentnea Creek, and other

streams. Natural deposits of phosphate occur in

Miocene and Cretaceous sediments of the AlbemarlePamlico Drainage Basin and produce high

concentrations (median = 0.2 milligram per liter

[mg/L]) of phosphorus in ground water. Because of

natural geologic sources, control of phosphorus

concentrations in streams in these basins may be

difficult for water managers (p. 12–14).

• Phosphorus and nitrogen concentrations in streams

generally have declined since 1980 in all four basins.

This decrease is probably the result of improved

agricultural practices, a phosphate detergent ban in

North Carolina and Virginia in 1988, and enhanced

wastewater-treatment practices. However, phosphorus

and nitrogen concentrations are still high enough in the

Tar and Neuse River Basins to cause nuisance algal

growths (p. 15).

NUTRIENTS IN GROUND WATER

• Water in about 4 percent of 49 shallow monito

wells randomly placed in agricultural areas of 

Coastal Plain exceeded the 10 mg/L drinking-w

standard for nitrate (U.S. Environmental Protec

Agency, 1986). Nitrate-nitrogen concentration

shallow ground water of the inner Coastal Plai

significantly higher than nitrate-nitrogen

concentrations in the outer Coastal Plain (p. 8)

• Highest nitrate concentrations in shallow groun

are in well-drained, sandy soils in combination 

intensive agricultural activity, such as crop or l

production. Residents in Coastal Plain areas ha

high nitrate can avoid water with high nitrate

concentrations by using water from deeper aqu

Nitrate concentrations in shallow ground water 

decreased by limiting fertilizer and manure

applications on crops in these areas (p. 14).

PESTICIDES

• Of 47 pesticides analyzed in stream samples, 4

detected. Metolachlor, atrazine, alachlor, and p

were the most commonly detected pesticides in

streams. Highest incidence of pesticide detecti

occurred in the Tar River Basin (p. 16).

• During the 1993–95 pesticide sampling period

concentrations of atrazine, alachlor, metolachlo

prometon in streams increased in late May and 

June and decreased gradually through August u

applications increased the following spring. Dr

water standards for pesticides are most likely t

violated during May through July (p. 16–17).

• Of 47 pesticides analyzed in shallow ground-w

samples, 14 were detected. Atrazine, deethylat

and metalachlor were the most commonly dete

pesticides. Concentrations in ground water gen

were less than 0.1 mg/L and never exceeded dr

water guidelines (U.S. Environmental Protectio

Agency, 1986). Breakdown products from atra

were detected, but no drinking-water standards

currently are established for these chemicals (p

OTHER ORGANIC COMPOUNDS AND TRAC

ELEMENTS

• Despite the 1972 ban against the use of the

organochlorine pesticide DDT in the United St

pesticide and its metabolites DDD and DDE pe

the environment. In an examination of data fro

to 1990, all sites sampled for bed sediment in t

River Basin for DDD, DDE, and DDT had

concentrations greater than the effects range
U.S. Geological Survey Circular 11

SUMMARY OF WATER-QUALITY ISSUES AND MAJOR FI

established by the National Oceanic and Atmospheric

Administration (Long and Morgan, 1991) as being

associated with adverse biological effects on some

benthic invertebrates (p. 18).

• DDD, DDE, DDT, dieldrin, trans-nonalachlor,

polychlorinated biphenyls (PCBs), and toxaphene were

detected in Asiatic clam or redbreast sunfish collected

at 11 of 19 sites during 1992–93. DDE was the most

common and widespread organochlorine compound

detected. Except for one detection of toxaphene,

pesticide concentrations were well below guidelines for

the protection of fish-eating wildlife (p. 18–19).

• All 10 of the U.S. Environmental Protection Agency

trace-element priority pollutants were detected in either

Asiatic clam or redbreast sunfish in relatively low

concentrations. Mercury concentrations were highest in

heavily stained blackwater streams (p. 19).

• Mercury was widely detected, being present in 29 of 30

tissue samples, but concentrations did not exceed the

Federal Food and Drug Administration (FDA) action

limit (Nowell and Resek, 1994) or a risk-based

screening value for the general public (Cunningham

and others, 1992) (p. 19).

FISH COMMUNITIES

• Differences in the numbers and kinds of fish in 

Coastal Plain streams were strongly related to

basinwide habitat characteristics, such as soil d

proportion of adjacent areas of forested wetlan

streams, amount of row-crop agriculture, and

channelization. Differences in fish communitie

more weakly related to site-specific habitat var

such as the amount of instream woody cover. T

results indicate that mitigation and restoration

strategies, which are of local focus but neglect

basinwide conditions, may not be fully success

(p. 21).

• Channelized streams in agricultural areas with 

drained soils tended to have the greater number

species associated with flowing water environm

than with ponded environments (p. 21).

• Agricultural land use, channelization, and dest

of floodplain buffer zones affect fish communi

altering flow regimes, decreasing the amount of 

material entering the stream, increasing nutrien

concentrations, and raising pH. Fish communit

composition responds to these changes by shif

toward species that prefer flowing, well-oxyge

water that is moderately to weakly acidic (p. 2

Albemarle Sound, North Carolina
4 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

ENVIRONMENTAL SETTING AND HYDROLOGIC CONDITIONS

surface and ground wate

mountains. Different roc

and the associated soils 

influence the nature and 

of minerals dissolved in 

waters.

Land use, population

distribution, and manma

reservoirs have significan

on water quality in the s

area. In general, the stud

dominated by a patchwo

forested (50 percent of th

and agricultural (more th

percent) lands, with larg

of wetlands (about 15 pe

the eastern Coastal Plain 

Less than 5 percent of th

basin area contains urba

The principal agriculture 

basin includes corn, soyb

cotton, peanut, tobacco, 

and potato cultivation an

chicken, turkey, hog, and 

production. Agricultural 

The Albemarle-Pamlico Drainage Basin, located in North

Carolina and Virginia, drains an area of about 28,000 square

miles (mi2) (fig. 1). Four physiographic regions—the Valley

and Ridge, Blue Ridge, Piedmont, and Coastal Plain

Provinces—are included within the Albemarle-Pamlico

Drainage area. For this study, the Coastal Plain was further

divided into the inner Coastal Plain and the outer Coastal

Plain (Harned and others, 1995).

Figure 1. Four major rivers—the Chowan, Roanoke, Tar,

and Neuse—drain into the Albemarle and Pamlico Sounds in

North Carolina.

Figure 2. Forested and agricultural lands dominate 

study area with extensive wetlands in the eastern pa

the mountains where slopes are steep, surface water 

shallow ground water move fast and have less oppor

dissolve rock and soil or undergo other geochemical

processes, such as ion exchange or adsorption; conse

the water generally contains very little dissolved min

matter. In the Piedmont and Coastal Plain, slopes are 

and water moves more slowly; consequently, surface 

there generally has two to three times the mineral co

Water quality in the Albemarle-Pamlico Drainage area is

affected by natural and cultural factors. Major factors include

physiography, soils, geology, precipitation, and land use and

are similar within each physiographic province.

The physiography, geology, and soils form the container

over and through which surface and ground water flow. In

River

R.

Blue

Ridge

Blue Ridge/Valley

and Ridge

Piedmont

Inner Coastal

Plain

 Outer Coastal

Plain

Study

area

VIRGINIA

NORTH CAROLINA

LOCATION OF STUDY AREA AND PHYSIOGRAPHIC PROVINCES

IN NORTH CAROLINA AND VIRGINIA

Roanoke

Roanoke River

Otter

Blacksburg River

N. Fork

Roanoke R.

Pigg River

WinstonSalem

Hyco

Lake Hyco 

 R.

Nottoway

River

Meherrin

Roanoke 

Rapids

Virginia Beach

Blackwater

River

Tar

River Falls

Lake

Flat

R.

Neuse

Swift

River

Cr.

MiddleCr.

Little

River

Raleigh

Durham

Neuse River

Contentnea

Cr.

Kinston

Chowan

Albemarle Sound

Pamlico River

Pamlico

Sound

Neuse River

Atlantic

Ocean

Chesapeake Bay

North Carolina

Virginia

Kerr

Lake

Lake

Gaston

Dan

 River

76o 77o 78o 79o 80o

37o

36o

35o

20 40 60 MILES

0 20 40 60 KILOMETERS

0

35o

36o

37o

80o 79o 78o 77o 76o

URBAN LANDS

AGRICULTURAL LANDS

WETLANDS

FORESTED LAND

HYDROLOGIC UNIT 

 BOUNDARY

EXPLANATION

0 50 MILES

0 50 KILOMETERS

A

Pamlico

Sound

Albemarle Sound

NORTH CAROLINA

VIRGINIA

urban land uses have the greatest potential to affec

quality because these land uses are the sources of l

amounts of nutrients, sediments, and pesticides.
4 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

ENVIRONMENTAL SETTING AND HYDROLOGIC CONDITIONS

Average annual precipitation ranges from 36 inches in the

western part of the Albemarle-Pamlico Drainage Basin to 52

inches in the eastern part of the basin (McMahon and Lloyd,

1995). This water leaves the basin by way of streams and

ground water.

In general, more than one-half of the water flowing in

streams discharging to the Albemarle-Pamlico Drainage

Basin comes from ground water. Thus, the quality of ground

water has substantial influence on surface-water quality.

Major aquifers in the Valley and Ridge, Blue Ridge, and

Piedmont Provinces are fractured rocks overlain by unconsolidated regolith; in the Coastal Plain Province, aquifers are

primarily unconsolidated and partly consolidated sands with

some limestone and sandy limestone.

Streamflow in the Roanoke River at Roanoke Rapids,

N.C., was higher during the study period, 1992–95, than

during the long-term period of record (1930–95) (fig. 3).

Higher streamflows tend to exacerbate nonpoint surfacerunoff pollution and dilute point-source pollution. Except

during March, streamflow in the Neuse River at Kinston,

N.C., was slightly lower during the study period than during

the long-term period of record (1930–95) (fig. 3). Lower

streamflows tend to exacerbate point-source pollution and

diminish nonpoint surface-runoff pollution.

Average water use during 1990 in the Albemarle-

Drainage Basin was about 2,800 million gallons per 

(Mgal/d) (McMahon and Lloyd, 1995). Most of this 

from surface water (90 percent) with the remaining 

percent supplied from ground water (fig. 4). About 3 

people live in the basin, and 11 percent of all water u

for public or domestic drinking water. Two-thirds of 

population obtains water from public water-supply s

most of which (75 percent) is from surface water; th

remaining one-third of the population uses ground w

supplied by private domestic wells (fig. 4).

Figure 3. Streamflow was higher in the Roanoke River

during the study period than during the long-term period of

record, and except during March, streamflow was slightly

lower in the Neuse River during the study period than during

the long-term period of record.

Figure 4. Surface water is used most in the study 

and the generation of thermoelectric power uses th

water.

8,000

7,000

6,000

5,000

4,000

3,000

2,000

1,000

0

16,000

14,000

12,000

10,000

8,000

6,000

4,000

2,000

0

STREAMFLOW, IN CUBIC FEET PER SECOND

Roanoke River at

Roanoke Rapids, N.C.

Neuse River at

Kinston, N.C.

ON DJ FMAMJ J AS

1930-95

1992-95

1930-95

1992-95

Top of bar represents median

monthly streamflow

Top of bar represents 

median monthly

streamflow

0

500

1,000

1,500

2,000

2,500

3,000

TOTAL 

PUBLIC

SUPPLY

DOMESTIC

SUPPLY

COMMERCIAL 

INDUSTRIAL AND

MINING 

IRRIGATION AND

LIVESTOCK 

THERMOELECTRIC

GROUND WATER 

SURFACE WATER 

POPULATION SERVED,

 IN THOUSANDS 

(1,956)

(839)

(1,956)

WATER WITHDRAWALS, IN MILLION

 GALLONS PER DAY 

Canoeing in Contentnea Creek, North Carolina
6 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

MAJOR ISSUES AND FINDINGS

Nutrients in Streams and Ground Water

Major sources of nutrients in the AlbemarlePamlico Drainage Basin are fertilizer,

livestock, precipitation, and point sources.

Streams draining a basin can become contaminated from

nonpoint (dispersed, both human and natural sources) and

point (concentrated, such as discharge from a pipe into a

river or stream) sources of nutrients. Nonpoint sources of

nutrients derived from fertilizers, animal wastes, or septic

fields are probably the main sources of ground-water

contamination. Geologic deposits can be important nonpoint

nutrient sources in some areas. Precipitation also can be a

major nonpoint source of nitrogen (fig. 5). Point sources

compose 6 percent or less of all nitrogen inputs and 16

percent of all phosphorus inputs.

NUTRIENTS AND ALGAE—A

POTENTIAL PROBLEM

Nutrients are elements that are necess

for the growth and nutrition of plants and

animals. Nitrogen and phosphorus typica

are the principal elements that limit the gr

of algae. Algal cells have a nitrogen-tophosphorus ratio of about 7 to 1; therefor

when the ratio of nitrogen to phosphorus 

water is 7 to 1 or greater, growth can incr

significantly. When a limiting nutrient beco

abundant, algal populations are stimulate

grow rapidly to extreme numbers until the

off. The organic load then causes fishkills

human health problems, and esthetic

deterioration of the water body. The

Albemarle-Pamlico estuaries are season

nitrogen limited. Unlike most freshwater

riverine systems, the lower portions of the 

Pamlico and the Neuse Rivers were also

nitrogen limited (Harned and Davenport,

1990), implying an unusually high source 

phosphorus in these basins.

In the Neuse River, excess nitrogen is

considered to be such a problem that the

State of North Carolina has considered a

30-percent reduction in nitrogen loads to 

river over the next 5 years, beginning in 1

(North Carolina Division of Water Quality

written commun., 1996).

Nitrate and ammonia are the forms of

nitrogen that are most important in contro

algal growth because they are available f

uptake by plants. Nitrogen in either of the

forms is a potential problem in regard to w

quality in the estuaries because excess

amounts are associated with algal bloom

fishkills, and toxicity to rooted aquatic pla

The Chowan River Basin had the highest

nitrogen input, primarily due to fertilizer; the

Neuse River Basin had the highest

phosphorus input, primarily due to livestock.

The nutrient inputs into each of the major basins can be

an indication of potential stresses on water quality. The

Chowan Basin received the largest inputs of nitrogen in

1990 (McMahon and Lloyd, 1995). The Roanoke Basin

received the smallest inputs of nitrogen.

0

NITROGEN

200

400

600

800

1,000

1,200

1,400

1,600

PHOSPHORUS

0

120

140

80

100

40

20

60

FERTILIZER

EXPLANATION

LIVESTOCK

PRECIPITATION

POINT SOURCE

HUNDREDS OF TONS

Chowan Roanoke

BASIN

Tar Neuse Basin

Total

Figure 5. The major sources of nitrogen inputs to the

Albemarle-Pamlico Drainage Basin, in order of importance,

are fertilizer, precipitation, livestock, and point-source

discharges to streams; and major sources of phosphorus

inputs are livestock, fertilizer, and point sources (McMahon

and Lloyd, 1995).

Wetlands in the Neuse River Basin, North Carolina
U.S. Geological Survey Circular 11

MAJOR ISSUES AND FI

Nutrients in Streams and Groun

Fertilizers provided more than 60 percent of the nitrogen

inputs in the Chowan, Tar-Pamlico, and Neuse Basins. The

main sources of nitrogen in the Roanoke Basin were

precipitation and fertilizer. Precipitation provided about 20

to 30 percent of the total nitrogen inputs in all four basins.

Permitted point-source inputs of nitrogen, however, were

less than 6 percent in all four basins.

Phosphorus input was highest in the Neuse Basin and

lowest in the Chowan Basin. Livestock contributed the

greatest input of phosphorus in the Roanoke and Neuse

Basins. Fertilizer was the major source of phosphorus in the

Chowan and Tar-Pamlico Basins and the second highest

source of phosphorus in the Roanoke and Neuse Basins.

Permitted point sources were significant contributors in the

Roanoke, Tar-Pamlico, and Neuse Basins, but were less than

0.5 percent of the contributors in the Chowan. Other

potential nonpoint sources, such as natural geologic deposits

(discussed in this report for phosphorus, p. 12), can be

significant, although estimates have not been included here.

Forested portions of the Chowan Basin had

the lowest nutrient yields per square mile;

agricultural basins of the Neuse and upper

Roanoke Rivers had the highest nutrient

yields.

Not all of the nutrients that enter a basin actually enter the

streams draining the watershed. The mass of nutrients that

leave a watershed in streamflow over a period of time is

termed “load.” The load per square mile (usually tons per

square mile) is termed “yield.” In the Albemarle-Pamlico

Drainage Basin, McMahon and Woodside (1997) reported

that as much as 50 percent of nutrients are retained in the

watershed. This is because nutrients may be tied up in

nonmobile forms in soils or undergo chemical

transformation. However, in general, urban and agricultural

land uses would be expected to yield more nutrients and

other chemicals to streams compared to other, less chemicalintensive, land uses. In the Albemarle-Pamlico Drainage

area, forested basins in the Chowan Basin had the lowest

nutrient yields, whereas the more urban and agricultural

basins—Contentnea Creek, the Neuse River, and the Tar

River in the Coastal Plain and the Dan River in the

Piedmont—all had the highest yields (fig. 6).

Typical concentrations of nutrients in streams

and ground water of the Albemarle-Pamlico

Drainage Basin generally do not exceed

drinking-water or aquatic-life standards,

although concentrations are among the

highest measured in 20 NAWQA Study Units.

The median concentration of nitrate as nitrogen was about

0.5 mg/L for 76 surface-water sites and 0.05 mg/L for 49

ground-water sites sampled in the Albemarle-Pamlico

Drainage Basin. These median nitrate concentrations in

ground and surface water are well under the U.S

Environmental Protection Agency (USEPA) drinkin

standard of 10 mg/L as nitrogen. Throughout the en

Coastal Plain, only about 4 percent of wells sampled 

nitrate-nitrogen concentrations greater than the 10-m

drinking-water standard. Median ammonia concentr

surface water were 0.06 mg/L, also less than USEPA

aquatic-life standards; median ammonia concentrati

ground water were 0.13 mg/L. The median dissolved

phosphorus concentration in surface water was abou

0.07 mg/L and less than 0.04 mg/L in shallow groun

Based on pre-1980 data, deep ground water in the C

Plain had a median dissolved phosphorus concentrat

about 0.2 mg/L (Harned and others, 1995). No phos

standards exist for human health; however, concentra

dissolved phosphorus above 0.05 mg/L in lakes or in 

flowing into lakes and 0.1 mg/L in streams can caus

nuisance algal growths (National Technical Advisor

Committee, 1968; Mackenthum, 1969).

Compared with results from 19 other NAWQA St

Units, streams in the southern portion of the Albema

Pamlico Drainage Basin have nutrient concentration

among the highest 25 percent of nutrient concentrati

measured (p. 22). Nutrient concentrations in shallow 

water were among the lowest nationally (p. 24).

Concentrations of nutrients are higher i

agricultural and urban streams of the

Albemarle-Pamlico Drainage Basin.

In a review of 1980–90 data, Harned and others (

examined total nitrogen, total ammonia plus organic

nitrogen, total nitrite plus nitrate, and total ammonia

basinwide. Total nitrogen concentrations at most of 

larger stream sites generally are greater than 0.3 mg

level cited by Vollenweider (1971) for potential nuis

algal growth. Contentnea Creek has the highest total 

concentrations, followed by the Neuse, Tar, Dan, an

Blackwater Rivers, the other Chowan tributaries, and 

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Tar Neuse Contentnea Blackwater

BASIN

Nottoway Meherrin Roano

TONS PER SQUARE MILE

PHOS

NITR

Figure 6. Highest yields of nutrients occurred in Con

Creek and in the Neuse, Tar, and Dan Rivers. These 

have less than 50 percent forested land and more tha

percent agricultural land. Lowest yields were in foreste

(greater than 55 percent forest land) of the Roanoke 

Chowan Basins (Blackwater, Nottoway, and Meherrin 

(Data from Harned and others, 1995.)
8 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

MAJOR ISSUES AND FINDINGS

Nutrients in Streams and Ground Water

Roanoke River. This ranking reflects the relative intensity of

both urban and agricultural development in these basins. In

general, the most urban basins and those with the most

intensive agriculture have the highest nitrogen values.

However, the Roanoke River has low total nitrogen

concentrations because of upstream sedimentation and

assimilation of nitrogen in algal biomass in Kerr and Gaston

Lakes (fig. 1).

Total phosphorus concentrations are relatively uniform in

the Dan River, increase downstream in the Tar River, and

peak in the Neuse River near Smithfield in a manner similar

to the pattern observed for nitrogen. A ranking of

phosphorus concentrations in surface water (Harned and

others, 1995) showed that basins with the most urban

development and intensive agriculture had the highest

phosphorus concentrations. Phosphorus concentrations were

frequently above 0.1 mg/L in most streams, providing an

ample supply of the nutrient for algal growth. Concentrations

of phosphorus less than 0.1 mg/L at Roanoke Rapids are

probably a result of settling of phosphorus in the sediments

of Kerr and Gaston Lakes and assimilation of soluble

phosphorus by algae. Concentrations of phosphorus in the

Neuse River Basin are the highest values of any in the

Albemarle-Pamlico Drainage Basin.

Nitrate concentrations in ground water exceed

drinking-water standards in 4 percent of wells.

Nitrogen usually occurs as nitrate in oxygenated surface

water or oxygenated shallow ground water. Excessive nitrate

in drinking water can cause blue-baby syndrome and is

associated with the occurrence of certain cancers (nonHodgkins lymphoma) in humans (Spruill and others, 1996).

About 4 percent of wells sampled throughout the Coastal

Plain produced water with nitrate concentrations that

exceeded the 10-mg/L drinking-water standard. The highest

concentrations of nitrate in shallow ground water are

associated with well-drained soils of the inner Coastal Plain

in the Albemarle-Pamlico Drainage Basin (fig. 7). However,

the highest nitrate-nitrogen concentration measured was

11 mg/L in an outer Coastal Plain sample. Low nitrate

concentrations in shallow ground water of the outer Coastal

Plain are due to denitrification or nitrate-reduction processes

Figure 7. Nitrate concentrations in shallow ground 

the inner Coastal Plain are significantly higher than n

concentrations in shallow ground water of the outer C

Plain.

35o

36o

37o

80o 79o 78o 77o 

20 40 60 MILES

0 20 40 60 KILOMETERS

0

North Carolina

Virginia

EXPLANATION

GREATER THAN OR EQUAL TO 10

GREATER THAN OR EQUAL TO 3 AND LESS THA

GREATER THAN OR EQUAL TO 0.6 AND LESS TH

LESS THAN 0.6

BLUE RIDGE/VALLEY AND RIDGE

PIEDMONT

INNER COASTAL PLAIN

OUTER COASTAL PLAIN

MEDIAN CONCENTRATION OF DISSOLVED 

NITRATE, IN MILLIGRAMS PER LITER

Summary statistics for nitrate-nitrogen concentrations in milligr

per liter. 

STATISTIC

Number of

 wells

Minimum

Median

Maximum

Percent >10 

 mg/L

49

0.05

0.05

11

4%

19

0.05

0.38

10

5%

0

0

ENTIRE

STUDY UNIT

INNER

COASTAL PLAIN

OU

COAST

Neuse River at Kinston, North Carolina

resulting from the large amounts of organic carbon i

poorly drained soils and sediments (Spruill and othe

1996).
U.S. Geological Survey Circular 11

MAJOR ISSUES AND FI

Nutrients in Streams and Groun

Nitrate concentrations were higher in small

agricultural streams than in other settings.

Nitrate concentrations in streams were highest (greater

than 1 mg/L) in heavily farmed areas in the AlbemarlePamlico Drainage Basin (fig. 8). Nitrate concentrations

which exceeded 1 mg/L occurred in the Tar and Neuse

Basins in small streams located in areas having at least 40

percent or more agricultural land.

Point-source discharges are a major sou

nitrate to the Tar and Neuse Rivers. Nitra

discharging ground water is probably no

major source of nitrogen to streams.

By correlating flow and nitrate concentrations in 

the sources of nitrate can be determined—a constant 

water source, point source, or from surface runoff. A

significant positive correlation indicates nonpoint so

surface runoff (increase in concentration as flow inc

whereas a significant negative correlation indicates d

at high flow—thus, a constant ground-water or point 

Negative correlations between nitrate and flow in the 

Neuse Rivers indicate that either ground-water base 

point sources are responsible for most of the nitrate.

However, concurrently collected samples of surface 

ground water at 25 sites in the Coastal Plain during 

flow period in September 1995 indicate that discharg

ground water had very low or undetectable nitrate

concentrations (fig. 9). This is probably because in a 

ground-water system, most nitrate undergoes reduct

denitrification in the aquifer before water is discharg

river. Deep ground water from long flow paths that d

to these rivers also typically is low in nitrate. The or

material on stream bottoms and fine-grained organic

sediments of the floodplains of streams cause discha

ground water to denitrify (fig. 10). Low nitrate

concentrations in discharging ground water is not a

significant source of nitrate in the streams. Although

naturally discharging ground water probably contrib

little nitrate to streams, artificial drainage techniques

tile drains and ditches which intercept the water tabl

contribute significantly as a nonpoint source of nitra

stream load. Gilliam and others (1997) reported that 

28 pounds per acre of nitrogen, on average, is releas

subsurface tile drains in agricultural areas of eastern 

Carolina.

Because naturally discharging ground water is no

the source of nitrate, the negative correlation with fl

indicates that point sources are the likely primary so

nitrate in the Neuse River and Tar River. Data presen

McMahon and Woodside (1997) indicate that point 

accounted for about 30 percent of the nitrogen load 

for the Neuse River at Kinston, N.C., and about 10 pe

the Tar River at Tarboro, N.C. Forty percent or more 

phosphorus load can be from point sources in the Ro

and Neuse Rivers. One outer Coastal Plain stream (V

Swamp), one inner Coastal Plain stream (Bear Creek

Piedmont stream (Devil’s Cradle Creek) showed sig

positive correlations of streamflow to nitrate, indicat

nitrate is derived primarily from nonpoint sources in 

runoff. Because both nitrate and ammonia are positi

correlated with streamflow in Devil’s Cradle and Be

Creeks, animal waste or septic systems are indicated 

primary sources. A significant positive correlation b

Figure 8. Small agricultural streams (sites 2 and 10) had

the highest overall nitrate concentrations. Of the large

streams draining more than 100 mi2, Contentnea Creek

(site 5), the Neuse River (site 8), and the Tar River (site 11)

had the highest median concentrations of nitrate, although

none exceeded the 10-mg/L drinking-water standard.

(Numbered sites are regularly sampled sites.)

1 2 3 4 5 6 7 8 9 10 11 12 0

1

2

3

NITRATE CONCENTRATION, IN 

MILLIGRAMS PER LITER

SITE NUMBER (See p. 26)

1

12

9 3

6

2

8

5

4

7

10

11

Top of bar represents median

for period, 1992-95

35o

36o

37o

80o 79o 78o 77o 76o

20 40 60 MILES

0 20 40 60 KILOMETERS

0

North Carolina

Virginia

EXPLANATION

GREATER THAN OR EQUAL TO 5

GREATER THAN OR EQUAL TO 1 AND LESS THAN 5

GREATER THAN OR EQUAL TO 0.1 AND LESS THAN 1

LESS THAN 0.1

BLUE RIDGE/VALLEY AND RIDGE

PIEDMONT

INNER COASTAL PLAIN

OUTER COASTAL PLAIN

MEDIAN CONCENTRATION OF DISSOLVED 

NITRATE, IN MILLIGRAMS PER LITER
10 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

MAJOR ISSUES AND FINDINGS

Nutrients in Streams and Ground Water

Figure 10. As ground water moves along the flow p

sandy aquifer in a small agricultural area of the Tar R

Basin (flow-path study area, p. 26) from the hilltop to 

canal, nitrate concentrations increase where fertilize

applied on the farmed field and remain high until the 

water passes through organic material in the stream

where concentrations are decreased as the ground w

discharges to the canal. Bacterially mediated denitrif

is primarily responsible for decreasing concentration

nitrate from 15 mg/L in ground water before discharg

the stream to 2 mg/L in the canal. Chloride undergoe

change as it discharges to the canal, indicating dilutio

responsible for the decrease in nitrate concentration

9

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

SYNOPTIC SITE NUMBER

CONCENTRATIONS, IN MILLIGRAMS PER LITER

N 1

2

3

4

5

6

7

8

10

11

12

13 14

15 16

17

18

19

20

21 22

23

24

25

 GROUND WATER

 STREAM WATER

DISSOLVED AMMONIA

DISSOLVED PHOSPHORUS

DISSOLVED NITRATE-NITROGEN

 GROUND WATER

 STREAM WATER

 GROUND WATER

 STREAM WATER

SYNOPTIC SITE

NUMBER BASIN SYNOPTIC SITE NAME

Sandy Run near Lizzie

Hominy Swamp at SR 1606

Van Swamp near Hoke

Neuse River at Kinston

Pete Mitchell Swamp near Pe

Middle Swamp near Lizzie

Nahunta Swamp at SR 1058

Little Contentnea Creek US 2

Little Contentnea Creek US 2

Durham Creek at Edward

Devil's Cradle Creek

Contentnea Creek at NC 222

Contentnea Creek at Hooker

Contentnea Creek at Evansd

Chicod Creek at SR 1760

Bloomery Swamp near Wilso

Bear Creek near Mays Store

Albemarle Canal

Scuppernong River at SR 11

Knobs Creek near Elizabeth 

Kendrick Creek at SR 1125 

Tar River at Tarboro

Newland Canal near Lynch's 

Goodwin Mill Creek at SR 11

Perquimans River at SR 120

N

N

T

N

T

N

N

N

N

T

T

N

N

N

T

N

N

T

T

A

A

T

A

A

A

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

Summary of synoptic site numbers, basin locations, and syn

site names. Drainage basins: N, Neuse; T, Tar; A, Albemarle

Piedmont Coasta

VIRGINIA

NORTH CAROLINA

Figure 9. Nitrate concentrations are low or barely detectable in discharging ground water compared to stream wate

sites sampled in the Coastal Plain, whereas ammonia and phosphorus concentrations tend to be higher in ground wa

discharging into the streams.

SAMPLING

SITE

Well 2A

Well 3B

Bed well

Canal

<1 mg/L

15 mg/L

18 mg/L

2 mg/L

15 mg/L

22 mg/L

17 mg/L

20 mg/L

NITRATE-NITROGEN

CONCENTRATION

CHLORIDE

CONCENTRATION

Farmed

field Well 2A

Well 3B Denitrification 

processes in 

streambed

Bed well

Base of aquifer

Ground water

Canal Flow path 
U.S. Geological Survey Circular 11

MAJOR ISSUES AND FI

Nutrients in Streams and Groun

flow and nitrate also indicates a surface nonpoint source of

nitrate at Van Swamp, a small blackwater stream.

High ammonia-nitrogen concentrations in

shallow ground water and surface water are

associated with high organic carbon

concentrations.

Nitrate is the main form of nitrogen in aerated waters with

low organic carbon concentrations. However, nitrogen also

exists in reduced form as ammonia (the ionized form of

ammonia is generally termed ammonium; however, for this

report, the ionized form will be referred to as ammonia) in

low-oxygen waters; thus, when nitrogen occurs in water as

ammonia, nitrate concentrations usually are low. Even

though ammonia is not known to be toxic to humans or fish

under typical concentrations or conditions, it is a

biologically available form of nitrogen which can contribute

to eutrophication. Ammonia can originate from decaying

organic material, animal or human wastes, fertilizer, or from

nitrate or nitrite that has moved into an anaerobic zone

containing large concentrations of carbonaceous material

(Spruill and others, 1996). Organic carbon, present in water

and sediments of the Coastal Plain, allows bacteria to reduce

nitrate to nitrogen gas and reduced nitrogen species.

Ammonia-nitrogen concentrations in ground water ranged

from less than 0.01 to 2.8 mg/L in the Albemarle-Pamlico

Drainage Basin with highest concentrations in the outer

Coastal Plain (fig. 11).

Stream concentrations of ammonia in the AlbemarlePamlico Drainage Basin are relatively high compared to

other parts of the United States (Mueller and others, 1995).

Concentrations of ammonia in ground water discharging into

streams in the Coastal Plain (fig. 9) were much higher

(median = 1.2 mg/L) than concentrations in shallow ground

water from randomly sampled wells throughout the Coastal

Plain (median = 0.135 mg/L; fig. 11). The highest ammonia

concentrations in streams occurred in Contentnea Creek and

in small Coastal Plain streams. Elevated concentrations of

ammonia in these streams may be due partly to discharging

ground water or point-source discharges, although ammonia

largely sorbs to bed material as indicated by much lower

stream concentrations compared to ground water (fig. 9). In

Bear Creek and Chicod Creek (fig. 12, sites 2 and 4), some

ammonia may be due to animal wastes.

Figure 11. Ammonia-nitrogen concentrations in gro

water were higher in the outer Coastal Plain (median 

0.250 mg/L) than in the inner Coastal Plain (median 

0.040 mg/L). The presence of abundant organic carb

sediments of the outer Coastal Plain probably cause

higher concentrations of ammonia.

35o

36o

37o

80o 79o 78o 77o 

MEDIAN CONCENTRATION OF DISSOLVE

AMMONIA, IN MILLIGRAMS PER LITER

EXPLANATION

GREATER THAN OR EQUAL TO 1

GREATER THAN OR EQUAL TO 0.5 AND LESS T

GREATER THAN OR EQUAL TO 0.1 AND LESS T

LESS THAN 0.1

BLUE RIDGE/VALLEY AND RIDGE

PIEDMONT

INNER COASTAL PLAIN

OUTER COASTAL PLAIN

Summary statistics for ammonia-nitrogen concentrations in 

per liter. 

STATISTIC

Number of

 wells

Minimum

Median

Maximum

50

0.010

0.135

2.80

19

0.010

0.040

0.700

ENTIRE

STUDY UNIT

INNER

COASTAL PLAIN

O

COA

20 40 60 MILES

0 20 40 60 KILOMETERS

0

North Carolina

Virginia

“Nitrogen-burned” lawn from too much fertilizer app
12 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

MAJOR ISSUES AND FINDINGS

Nutrients in Streams and Ground Water

Figure 12. Concentrations of ammonia exceeding

0.1 milligram per liter occurred in streams throughout much

of the study area. Much of the ammonia may be associated

with discharging ground water or animal wastes.

High phosphorus concentrations in som

streams are due to high concentrations 

ground water.

Phosphorus does not commonly occur in ground w

concentrations greater than a few hundredths of a m

per liter because it tends to chemically attach, or sor

positively charged particles in soils and clays. In gen

phosphorus concentrations in shallow ground water 

Coastal Plain of the Albemarle-Pamlico Drainage B

reflect this in as much as the overall median phospho

concentration was 0.035 mg/L (fig. 13). However, de

ground water in North Carolina had a median conce

of about 0.25 mg/L (Harned and others, 1995) comp

much lower median concentration in shallow ground 

These relatively high concentrations of phosphorus a

derived from phosphate minerals, such as fluoroapat

the aquifer sediments. The upward discharge of this 

ground water into shallow aquifers of the outer Coas

may account for the slightly higher concentration co

to that of the inner Coastal Plain (fig. 13).

Deep ground water also affects stream-water qual

Where phosphorus-rich, deep ground water discharg

streams, it affects surface-water quality. Results from

sampling 25 sites during August and September 199

throughout the Coastal Plain indicate that phosphoru

concentrations in discharging ground water generall

higher than in surface water (fig. 9).The median pho

concentration in discharging ground water from thes

sites was 0.2 mg/L, about the same concentration rep

Harned and others (1995) for deep ground water fro

inner Coastal Plain. The median concentration of pho

in surface water at these sites was 0.1 mg/L. Ground

phosphorus concentrations affect surface-water phos

concentrations, as indicated by a significant correlat

all 25 sites between discharging ground-water concen

and stream concentrations. Concentrations of phosph

discharging ground water were highest in Contentne

Chicod Creeks and in the Neuse and Tar Rivers. A n

correlation between flow and instream dissolved pho

was found in these basins, indicating that discharging 

water and point sources are the primary sources of

phosphorus.

35o

36o

37o

80o 79o 78o 77o 76o

20 40 60 MILES

0 20 40 60 KILOMETERS

0

North Carolina

Virginia

GREATER THAN OR EQUAL TO 0.15

GREATER THAN OR EQUAL TO 0.1 AND LESS THAN 0.15

GREATER THAN OR EQUAL TO 0.003 AND LESS THAN 0.1

LESS THAN 0.003

BLUE RIDGE/VALLEY AND RIDGE

PIEDMONT

INNER COASTAL PLAIN

OUTER COASTAL PLAIN

MEDIAN CONCENTRATION OF DISSOLVED 

AMMONIA, IN MILLIGRAMS PER LITER

EXPLANATION

1

2

3

4

5

6

7 8

9

10

11

12

1

0

0.1

0.2

0.3

0.4

2 3 4 5 6 7 8 9 10 11 12

AMMONIA CONCENTRATION, IN

MILLIGRAMS PER LITER

SITE NUMBER (See p. 26)

Top of bar represents median

for period, 1992-95

Sampling a well in the Coastal Plain, North Carolina
U.S. Geological Survey Circular 11

MAJOR ISSUES AND FI

Nutrients in Streams and Groun

Figure 13. Shallow ground water from the outer Coastal

Plain has significantly higher total phosphorus

concentrations than does shallow ground water from the

inner Coastal Plain. These higher concentrations, due to

the presence of phosphorus minerals in the underlying

aquifer sediments, may be a result of deep ground-water

discharges into the surficial aquifer from long regional-flow

systems in sands of Cretaceous age in the Coastal Plain.

Figure 14. The high concentrations of phosphorus m

in samples from Chicod Creek (site 4), Contentnea Cr

(site 5), Neuse River (site 8), and Tar River (site 11) a

probably due to ground water and(or) point-source dis

Summary statistics for phosphorus concentrations in milligrams per liter.

STATISTIC

Number of

 wells

Minimum

Median

Maximum

50

0.010

0.035

1.40

19

0.010

0.040

1.30

30

0.010

0.070

1.40

ENTIRE

STUDY UNIT

INNER

COASTAL PLAIN

OUTER

COASTAL PLAIN

35o

36o

37o

80o 79o 78o 77o 76o

EXPLANATION

GREATER THAN OR EQUAL TO 1

GREATER THAN OR EQUAL TO 0.5 AND LESS THAN 1

GREATER THAN OR EQUAL TO 0.1 AND LESS THAN 0.5

LESS THAN 0.1

BLUE RIDGE/VALLEY AND RIDGE

PIEDMONT

INNER COASTAL PLAIN

OUTER COASTAL PLAIN

MEDIAN CONCENTRATION OF DISSOLVED 

PHOSPHORUS, IN MILLIGRAMS PER LITER

20 40 60 MILES

0 20 40 60 KILOMETERS

0

North Carolina

Virginia

Of the 12 stream sites sampled regularly between 

and 1995, the highest median phosphorus concentra

were measured in samples from Chicod and Conten

Creeks and from the Neuse and Tar Rivers (fig. 14)

the summer low-flow period when algal growth pot

highest, each of these four sites had concentrations 

phosphorus greater than 0.1 mg/L, ranging from abo

to 0.51 mg/L (fig. 15).

1

0

0.1

0.2

0.3

2 3 4 5 6 7 8 9 10 11 12

PHOSPHORUS CONCENTRATION, IN

MILLIGRAMS PER LITER

SITE NUMBER (See p. 26)

35o

36o

37o

80o 79o 78o 77o 

EXPLANATION

GREATER THAN 0.1

GREATER THAN OR EQUAL TO 0.05 AND LESS THA

GREATER THAN OR EQUAL TO 0.01 AND LESS THA

LESS THAN 0.01

BLUE RIDGE/VALLEY AND RIDGE

PIEDMONT

OUTER COASTAL PLAIN

INNER COASTAL PLAIN

MEDIAN CONCENTRATION OF DISSOLVED 

PHOSPHORUS, IN MILLIGRAMS PER LITER

Top of bar represents 

median for period, 

1992-95

North Carolina

Virginia

1

2

3

9

6

7

4

8

10

11

12

5

20 40 60 MILES

0 20 40 60 KILOMETERS

0

Sampling ground water discharging to

a stream
14 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

MAJOR ISSUES AND FINDINGS

Nutrients in Streams and Ground Water

1234567

EXPLANATION

SITE NUMBER (See p. 26)

8 9 10 1112

MAXIMUM FOR FLOWING WATER

MAXIMUM FOR PONDED WATER

 OR STREAM FLOWING INTO

 PONDED WATER

TOTAL PHOSPHORUS, IN

MILLIGRAMS PER LITER

Top of bar represents 

median summertime 

concentrations

for period 1992-95

0.55

0.50

0.45

0.40

0.35

0.30

0.25

0.20

0.15

0.10

0.05

0

Figure 15. The highest summertime (June–August) concentrations of phosphorus were detected in Chicod Creek (site 4),

probably due to animal waste, and in Contentnea Creek

(site 5), the Neuse River (site 8), and the Tar River (site 11),

probably due to ground-water inputs and(or) point sources.

To meet literature-based guidelines, a 30-

to 50-percent reduction in nutrient

concentrations is needed to reduce

nuisance algal production in streams of

the Tar and Neuse River Basins.

 In general, summer is the time when algal growths are at

their maximum and also when nutrients are most important in

limiting algal growths. Summer concentrations of phosphorus

(fig. 15) and nitrogen (fig. 16) are particularly high in Chicod

Creek, the Neuse River, the Tar River, and Contentnea Creek.

For Contentnea Creek, a 30- to 50-percent reduction in

phosphorus concentration would be necessary to attain the

0.1-mg/L phosphorus guideline (Mackenthum, 1969); for the

Neuse River, a 50-percent reduction in phosphorus

concentration would be required to approximate the

0.05-mg/L guideline for streams flowing into lakes or

quiescent water (as in the Neuse estuary). Additional sources

of phosphorus from sediments, however, could reduce the

effectiveness of nutrient source controls in the estuary.

Median summertime concentrations of total nitrogen are

higher than 1 mg/L in several streams, including the Tar River,

Contentnea Creek, and the Neuse River (fig. 16). After

phosphorus reductions and assuming a 7:1 cellular growth

ratio of nitrogen to phosphorus, median summer nitrogen

concentrations would need to be less than 0.7 mg/L for the Tar

River and Contentnea Creek and 0.3 to 0.5 mg/L for the Neuse

River to reduce algal growth. The Neuse River would require

about a 50-percent nitrogen reduction, and the Tar River and

Contentnea Creek each would require about a 30-percent

reduction in total nitrogen to reduce the incidence of nuisance

algal growth, fishkills, and undesirable odors. Natural geologic

sources of phosphorus in these basins may make concentration

reductions difficult for water managers.

Figure 16. H

summertime (

August) total 

concentration

detected in A

Canal (site 1)

Creek (site 2)

Creek (site 4)

Contentnea C

(site 5), Neus

(site 8), Pete 

Swamp (site 1

River (site 11)

Swamp (site 1

Nutrients in ground water are a problem 

some areas.

Although only 4 percent of wells sampled by NA

across the Coastal Plain exceeded the 10 mg/L drink

standard, highly vulnerable areas in the inner Coasta

having well-drained soils and agricultural land uses 

more susceptible to nitrate concentrations. Almost 4

of the ground-water samples collected by the North 

Division of Water Quality in these areas exceeded th

10-mg/L drinking-water standard (Spruill and other

Limiting fertilizer or manure applications in such ar

developing deeper ground-water supplies that are pr

from land-surface activities should minimize exposu

excessive nitrate concentrations. Although the amm

concentration in the outer Coastal Plain is high in gr

water discharged to freshwater streams, it does not a

greatly affect concentrations of ammonia in freshwa

streams (fig. 9); however, it may elevate stream amm

concentrations. Such discharges could affect estuari

the salt content of the estuary allows the ammonia to 

solution. Elevated ammonia concentrations in groun

may be related to bacterial nitrate reduction or relea

decay of organic material, particularly in aquifer dep

the outer Coastal Plain, or from animal or human w

Phosphorus concentrations in shallow wells gener

very low (less than 0.04 mg/L), although deeper form

Miocene and Cretaceous age contain concentrations 

phosphorus that are as high as 2 mg/L with a media

0.2 mg/L. Discharge of this deeper ground water to 

where these formations are present increases phosph

concentrations in streams of the Coastal Plain, parti

the Tar and Neuse drainage basins. It is also possible 

ground water accounts for the higher dissolved phos

concentrations in shallow ground water in the outer 

Plain. Elevated phosphorus concentrations contribut

eutrophication of streams and can stimulate growth 

organisms associated with fishkills, such as Pfiester

piscicida (Burkholder, 1997).

0

1

2

3

4

5

TOTAL NITROGEN, IN

MILLIGRAMS PER LITER

SITE NUMBER (See p. 26)

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

Top of bar represents 

median summertime 

concentrations for 

period 1992-95

Abundant nitrogen in these streams promotes exces

growth.
U.S. Geological Survey Circular 11

MAJOR ISSUES AND FI

Trends in Nutrients and Suspended S

Nutrient concentrations are decreasing in

streams in North Carolina, but some increases

were indicated in Virginia.

Total nitrogen trends for 1980–90 (Harned and others,

1995) indicate increases in the tributaries at the upper end of

Kerr Lake and decreases in the Neuse River Basin. The

increases in nitrogen concentrations upstream from Kerr

Lake reflect changes in atmospheric inputs of nitrogen,

possibly caused by construction of powerplants near the

lake. Decreases in nitrogen concentrations in the Neuse

River Basin are dissimilar, suggesting differing causes for

the decreases. Trends observed for total ammonia and

organic nitrogen were similar to those observed for total

nitrogen and nitrate nitrogen. Upward trends in nitrate also

were detected for two sites in the Tar River Basin and

probably are due to changes in agricultural practices. A

gradual increase in nitrate concentrations in the Chowan

River near Riddicksville was detected.

Total phosphorus concentrations generally showed

upward trends for streams in Virginia and downward trends

for streams in North Carolina. The effect of the 1988

phosphate-detergent ban in both States is evident at several

streams, including the Nottoway River, Neuse River, and

Contentnea Creek. Total phosphorus is strongly associated

with suspended sediment; therefore, locations having high

suspended-sediment concentrations, such as those in the

upper Roanoke and Dan River Basins, generally have high

phosphorus concentrations. Although decreases in nitrogen

and phosphorus have been observed, concentrations are still

high enough in the Tar and Neuse River Basins to cause

nuisance algal growth.

Suspended-sediment concentrations are

higher in the Piedmont than in the Coastal

Plain.

Suspended-sediment concentrations for the major rivers in

the Albemarle-Pamlico Drainage Basin from 1980 to 1990

generally were less than 50 mg/L with greater concentrations

occurring in Piedmont streams than in Coastal Plain streams

because of steeper slopes and more readily erodible soils in

the Piedmont (Harned and others, 1995). Kerr and Gaston

Lakes are effective traps for sediment in the upper Roanoke

River Basin, as is Falls Lake in the Neuse River Basin.

Substantial decreases in suspended-sediment concentrations

are evident in the Neuse River as it flows from the Piedmont

to the Coastal Plain. Agricultural activities, particularly

highly erosive corn and tobacco farming, combined with the

steep slopes of the Piedmont produce high sediment yields.

Median sediment concentrations for data collected from

1993 to 1995 during the NAWQA study were highest in the

Neuse River (25 mg/L), Devil’s Cradle Creek (15.5 mg/L),

and the Tar River (16.5 mg/L), probably due to the greater

slopes and higher degree of erosion of the Piedmont drainage

areas compared to those of the Coastal Plain. However, high

median concentrations in Coastal Plain streams—Al

Canal (15 mg/L) and Chicod Creek (14 mg/L)—indi

agricultural sources can have a substantial effect on s

concentrations in streams even in areas of low slope

Coastal Plain.

Suspended- and dissolved-solids concentrations h

decreased throughout the Albemarle-Pamlico Draina

Basin over the past 15 years (1980–95). The decreas

probably a result of (1) construction of new lakes an

which trap solids, (2) improved agricultural soil

management, and (3) improved wastewater treatmen

Decreasing concentrations of suspended solids in the 

and estuaries may result in clearer water and deeper 

penetration which, in turn, enhance conditions for al

blooms in nutrient-enriched areas.

Livestock in a stream in the Contentnea Creek Basin, North 
16 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

MAJOR ISSUES AND FINDINGS

Pesticides in Streams and Ground Water

35o

36o

37o

80o 79o 78o 77o 

1 TO 5

6 TO 20

GREATER THAN 20

BLUE RIDGE/VALLEY AND RIDGE

PIEDMONT

OUTER COASTAL PLAIN

INNER COASTAL PLAIN

NUMBER OF PESTICIDES DETECTED 

EXPLANATION

20 40 60 MILES

0 20 40 60 KILOMETERS

0

North Carolina

Virginia

The main pesticides used in the Albemarle-Pamlico

Drainage Basin include alachlor, atrazine, metolachlor,

carbaryl, carbofuran, and ethoprop. Recommended

application rates for most pesticides range from about

0.5 pound per acre (lb/acre) to 3 lb/acre. Alachlor, the

pesticide most used in the Albemarle-Pamlico Drainage

Basin, is applied at rates up to 3 lb/acre, primarily in peanut

cultivation. An application rate of about 1 lb/acre of many

other pesticides is used for other crops grown in the study

area. Some organochlorine pesticides that have long been

banned from use (such as DDT) are still present in streambed

sediments (see p. 18) in the basin and provide a source of

these pesticides for uptake by aquatic organisms.

Pesticides applied to crops in the study area

are measured at concentrations in shallow

ground water just above detection levels.

Of 47 pesticides and metabolites analyzed in groundwater samples from 49 wells less than 50 feet deep located

across the Coastal Plain, 14 were detected. Atrazine and its

metabolite, deethylatrazine, were the most commonly

detected pesticides (each in 16 percent of wells sampled).

Metolachlor and 2,6–diethylaniline (a formulation

component of alachlor) were each detected in 10 percent of

wells sampled. The remaining pesticides detected include

the insecticides carbofuran, carbaryl, chlorpyrifos, diazinon,

and dieldrin and the herbicides alachlor, prometon, simazine,

terbacil, and tebuthiuron. Most pesticide concentrations were

less than 0.1 microgram per liter ( g/L), and no pesticide

concentrations detected in water from any of the 49 wells in

the study area exceeded drinking-water standards or health

advisory levels (although many pesticides do not have

established standards). Pesticide detection rates in ground

water in the agricultural areas of the Coastal Plain were

among the highest nationally (p. 25). Occurrence of specific

pesticides in surface and ground water is presented in the

table on pages 28–33 of this report.

Low concentrations of pesticides were

commonly detected in the streams of the

Albemarle-Pamlico Drainage Basin.

Of 47 pesticides analyzed in surface-water samples, 45

pesticides were detected. Four streams in the Tar River Basin

had 20 or more pesticides detected, 30 streams had between

6 and 20 compounds detected, and samples from 21 streams

had detectable concentrations of 1 to 5 pesticides (fig. 17).

Sixteen pesticides, including four insecticides (carbaryl,

carbofuran, ethoprop, and diazinon) occurred at

concentrations greater than 0.1 g/L. Generally, herbicides

were detected in streams during the spring and summer

months. Concentrations of several pesticides (atrazine,

metolachlor) became elevated immediately after application

in March and April, peaked in June and July, and finally

dissipated to the detection limit or low concentrations for

most of the year (fig. 18). Based on these data, drinkingwater standards for pesticides are most likely to be v

during May through July.

Metolachlor was detected in 80 percent, atrazine 

percent, prometon in 60 percent, and alachlor in 63 p

of 233 stream samples from 65 sites in the Albemar

Pamlico Drainage Basin. Only alachlor exceeded the

drinking-water standard of 2 mg/L. Standards for dr

water or aquatic life exist for about 50 percent of the

compounds detected.

Figure 17. Twenty or more pesticides were detecte

stream sites. Streams with the greatest number of de

pesticide concentrations greater than 0.1 microgram 

were in agricultural areas in the Tar River Basin.

Pesticide application in the Contentnea Creek Basin, Nort
U.S. Geological Survey Circular 11

MAJOR ISSUES AND FI

Pesticides in Streams and Groun

Figure 18. Atrazine, alachlor, metolachlor, and prometon concentrations in selected streams usually peaked during

the principal period of herbicide application (May to June). Peaks in prometon concentration occurred in Devil’s Cradl

Creek from July to December.

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

MA MJ J

1993 1994

EXPLANATION

1993 1994

ASONDJ FM

CONCENTRATION OF METOLACHLOR,

IN MICROGRAMS PER LITER

DEVIL'S CRADLE CREEK

TAR RIVER AT TARBORO

PETE MITCHELL SWAMP

CHICOD CREEK NEAR SIMPS

ALBEMARLE CANAL

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

CONCENTRATION OF ATRAZINE,

IN MICROGRAMS PER LITER

3.6

3.2

2.8

2.4

2.0

1.6

1.2

0.8

0.4

0

1.0

0.8

0.6

0.4

0.2

0

CONCENTRATION OF ALACHLOR,

IN MICROGRAMS PER LITER

ATRAZINE ALACHLOR

METOLACHLOR PROMETON

M A MJ J A SOND J FM

CONCENTRATION OF PROMETON,

IN MICROGRAMS PER LITER

The Albemarle-Pamlico NAWQA Study Unit team collecting and processing ground- and surface-water samples
18 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

MAJOR ISSUES AND FINDINGS

Other Organic Compounds and Trace Elements in Bed Sediment, Tissues, and Ground Water

In addition to the 47 agricultural pesticides applied to

crops during the period 1992–95 and discussed in the

previous section, there are many other organic compounds

that can pose potential health and environmental hazards.

These organic compounds (chemical compounds containing

the element carbon) include organochlorine compounds

(compounds with both carbon and chlorine); semivolatile

organic compounds (SVOCs), which usually are the result of

combustion (polyaromatic hydrocarbons [PAHs]), either

natural or anthropogenic, or the product of industrial

manufacturing (phenols, phthalate esters, amines, and a

variety of other compounds); and volatile organic

compounds (VOCs) associated with refined gasoline

(benzene, toluene, xylene, methyl tert-butyl ether [MTBE])

or solvents, such as trichloroethene and carbon

tetrachloride). Many of the organochlorine compounds were

used extensively as pesticides (for example, DDT) during the

1950’s, 60’s and 70’s, but were largely banned during the

late 1970’s and early 1980’s because of their carcinogenicity,

toxicity, and ability to persist in the environment for many

years. They are generally not very water soluble. SVOCs

also do not easily evaporate into the atmosphere and are not

very water soluble. VOCs, on the other hand, evaporate

easily and are very water soluble. With the exception of

VOCs, only results of bed-sediment sampling are discussed.

Because VOCs are very soluble, they are discussed as a

contaminant in ground water.

Trace elements are another class of contaminants in water

and sediment that can pose environmental hazards. Trace

elements, as discussed in this report, include metals and

nonmetals; some elements, such as aluminum and iron,

actually are very common in the environment. However,

most of the elements analyzed as part of the NAWQA study

typically occur at low concentrations in the environment and,

thus, are termed “trace” elements. Trace elements can occur

locally at elevated concentrations as a result of enrichment

due to geologic processes, such as evaporite deposits, or to

anthropogenic processes, such as industrial, mining, or

agricultural activities. Only the occurrence of trace elements

in bed sediment of streams will be discussed in this report.

DDT, SVOCs, and trace elements were

detected in streambed sediment.

Many pesticides have very low solubility in water and

tend to adsorb (attach) to streambed sediment. Although

these compounds, mostly organochlorine pesticides, are

usually not detected in the water, they persist in bed

sediment and provide a source for bioaccumulation by

aquatic organisms. In addition, trace elements accumulate in

bed sediments and occur near urban areas as a result of

runoff or waste discharges from industrial, municipal, and

residential activities. Bioaccumulation of metals, such as

mercury, is a concern because trace levels in bed sediment

may be concentrated to harmful levels in organisms at the

top of the food chain.

Streambed sediments were collected in 1992 at 22 

and analyzed for 35 organochlorine pesticides, 63

semivolatile compounds, and 44 major, minor, and t

elements (Woodside and Simerl, 1996). DDT was de

in 27 percent, DDD in 40 percent, and DDE in 63 pe

the samples. DDD and DDE are degradation produc

DDT. DDT was banned from use in the United State

1972 yet persists in the environment. In addition, die

was detected in 18 percent and chlordane was detect

percent of the samples. DDT and its degradation pro

were detected in stations downstream from both urb

rural areas; chlordane was detected at two urban site

During a review of historical pesticide and trace-e

data for streambed sediment in the Albemarle-Pamli

Drainage Basin for 1969–90 (Skrobialowski, 1996), 

were examined from 1,049 samples collected at 301 

Chlordane concentrations greater than the effects ran

established by the National Oceanic and Atmospher

Administration (Long and Morgan, 1991) were dete

the upper Neuse River Basin, and elevated concentra

DDT, DDD, and DDE were detected at Tar River sit

several sites in the Roanoke River Basin. DDT was 

in 18 percent, DDD in 25 percent, and DDE in 28 pe

the approximately 160 samples analyzed.

Lead concentrations during the 1992 NAWQA sa

were highest in streambed sediments from Ellerbe C

Crabtree Creek, both of which are urban basins in th

River Basin. Mercury and cadmium concentrations i

streambed sediment were highest in the Trent River—

Coastal Plain stream in the Neuse River Basin. Zinc

concentrations were highest in Ellerbe Creek and th

River. Concentrations of chromium, lead, nickel, and 

were higher in streams draining urban areas and nea

wastewater-treatment plants than in other settings.

SVOCs were most commonly detected in bed sed

streams draining urban basins. Of 22 streams sample

throughout the Albemarle-Pamlico Basin (Woodside 

Simerl, 1996), the Roanoke River downstream from

Roanoke, Va., had the greatest number of SVOCs de

(36 of 63 compounds), most of which were PAHs. O

basic sites, Devil’s Cradle Creek (site 6, p. 26) had t

occurrences of phthalate esters, with one (bis 2-ethy

phthalate being the highest concentration (870 micro

per kilogram [ g/kg]) of any SVOC detected. Howev

phthalate esters are pervasive in the environment bec

compounds are used in the manufacturing of commo

plastics. In general, SVOC concentrations from all o

stream sites in the Albemarle-Pamlico Drainage Bas

relatively low and were few in number.

Pesticides were detected in Asiatic clam 

redbreast sunfish tissue samples.

Of the 28 organochlorine compounds analyzed, s

were detected in Asiatic clam soft tissues and whole

redbreast sunfish—DDD, DDE, DDT, dieldrin, tran

nonalachlor, PCBs, and toxaphene. Of these, DDE w
U.S. Geological Survey Circular 11

MAJOR ISSUES AND FI

Other Organic Compounds and Trace Elements in Bed Sediment, Tissues, and Groun

most common and widespread, being present at 11 of the 19

sites sampled. DDE is a chemically stable and persistent

metabolic breakdown product of DDT and is among the

most commonly detected organochlorine compounds

nationwide (U.S. Environmental Protection Agency, 1992).

More than one organochlorine compound was detected at 6

of the 19 sites. The only detection of toxaphene exceeded the

National Academy of Sciences and National Academy of

Engineering (NAS/NAE) guidelines for the protection of

fish-eating wildlife (Nowell and Resek, 1994). The

toxaphene exceedance occurred at Pete Mitchell Swamp—a

small, intensively farmed basin in the Coastal Plain. All of

the other detected compounds were present in concentrations

well below the NAS/NAE guidelines (Smith and Ruhl,

1996).

Redbreast sunfish appear to be better

bioindicators of organochlorine compound

contamination. Asiatic clams are better

bioindicators of PCB contamination.

Compared to the Asiatic clam, redbreast sunfish appear to

be better bioindicators of organochlorine compound

contamination in aquatic systems. Of the seven compounds

detected, all but PCBs were detected in whole redbreast

sunfish samples; only three compounds—DDE, transnonalachlor, and PCBs—were detected in Asiatic clam

samples. Pesticides were detected at all eight sites sampled

for redbreast sunfish, whereas only 3 of the 15 sites sampled

for Asiatic clams had detections above the minimum

reporting level. On the other hand, PCBs were only detected

in Asiatic clams, lending support to other studies which have

shown that Asiatic clams are good bioindicators of PCB

contamination (Peterson and others, 1994).

Trace elements were detected in biological

tissue samples.

Although all 10 of the USEPA trace-element priority

pollutants were detected in Asiatic clam soft tissues or

redbreast sunfish livers, they were present in relatively low

concentrations. The sampling methods used do not permit a

direct assessment of risks to human health; however, it is

unlikely that widespread trace-element contamination poses

a significant risk in the streams and rivers of the AlbemarlePamlico Drainage Basin. Mercury concentrations were

highest in blackwater streams and should continue to be

monitored on a regular basis (Ruhl and Smith, 1996).

Trace-element concentrations detected in Asiatic clams in

the study area were similar to those measured in other

NAWQA Study Units in the southeastern United States

(Ruhl and Smith, 1996). Mercury was widely detected, being

present in 29 of 30 tissue samples, but concentrations did not

exceed the FDA action limit of 1 microgram per gram ( g/g)

wet weight or a risk-based screening value for the general

public (3.2 g/gwet weight) (Cunningham and others, 1992).

Mercury concentrations in the study area ranged fro

to 0.33 g/g wet weight.

The highest concentrations of mercury were detec

redbreast sunfish from the Blackwater River (0.19 to

0.33 g/g wet weight), and Contentnea Creek (0.18 

wet weight). Both are Coastal Plain streams where h

concentrations of dissolved organic carbon also wer

measured. Higher mercury concentrations in fish are 

associated with high concentrations of dissolved org

carbon. Studies have indicated that waters with low 

high dissolved organic carbon concentrations, such a

Blackwater River, promote mercury uptake by aquat

organisms (Gilmore, 1995). Many Coastal Plain stre

lakes in North Carolina and Virginia have naturally 

and high dissolved organic carbon concentrations an

may be particularly susceptible to mercury bioaccum

Few VOCs were detected in shallow gro

water.

Volatile organic compounds (VOCs) were not com

detected in shallow ground water. VOCs can occur i

concentrations in ground water, usually in urban

environments. The most common sources of VOCs 

vehicle fuel and industrial discharges of solvents. M

VOCs are known to cause cancer or are toxic; theref

drinking-water standards have been established for t

compounds.

Only three VOCs (chlorobenzene,

trichlorofluoromethane, and MTBE) were detected in 

water in four separate wells in the Coastal Plain. All 

detected concentrations were below drinking-water

standards. In general, VOCs do not appear to occur 

throughout the Coastal Plain and probably do not po

concern except in local urban areas. The two highes

concentrations detected occurred in industrial/comm

land-use areas. A comparison of concentrations from 

in the Albemarle-Pamlico Drainage Basin with natio

NAWQA results indicates that VOC detections in gr

water were among the lowest in the Nation.

Collecting benthic invertebrates in the Neuse River Bas

North Carolina
20 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

MAJOR ISSUES AND FINDINGS

Fish Communities

A fish community is a group of fish species that live in the

same area and interact with one another (Meador and others,

1993). Community composition refers to the kinds of species

present and their absolute and relative abundances. Fish

community composition is significantly influenced by

factors affecting water-quality conditions, including land

use, land cover, point- and nonpoint-source pollution,

channelization, and wetland destruction. In order to assess

and describe these relations within the Coastal Plain of North

Carolina, fish, habitat, and water-chemistry data were

collected and analyzed for sites on 16 small (14- to 59-mi2

basins) and 5 large (602- to 2,700-mi2) Coastal Plain

streams. Only results for the 16 small streams are discussed

here.

The small Coastal Plain streams that were sampled had

relatively diverse fish communities. Forty-five fish species

from 15 different families were captured at the 16 sites. The

number of species (richness) captured at each site ranged

from 6 to 25 and was comparable to the number of species

found in streams in other areas of the southeastern Coastal

Plain (Paller, 1994).

Several species were present in nearly every stream and,

thus, compose the nucleus of what might be called a typical

Coastal Plain small-stream fish community. These species

include pirate perch, redfin pickerel, American eel, creek

chubsucker, yellow bullhead, and bluespotted sunfish. Other

species that were slightly less widespread and abundant

included golden shiner, eastern mosquitofish, tessellated

darter, and redbreast sunfish. Nearly half of the captured

species were members of either the sunfish (Centrarchidae)

or minnow (Cyprinidae) families (11 species each), which

together included about one-third of all the fish that were

captured.

Differences in fish communities among small

streams in the Coastal Plain are related to

basinwide soil drainage characteristics and

land use.

Although nearly every small stream site had many of the

typical Coastal Plain species, there were several important

characteristics of fish community composition that differed

among sites. These characteristics included species richness,

the relative abundances of typical Coastal Plain species, and

the presence and abundances of species that are associated

with particular kinds of stream habitats. In addition, the

differences were strongly related to basinwide environmental

characteristics, such as soil drainage, the amount of wetland

buffer, and land use.

Numbers of species were significantly correlated

(Spearman's rho; p <0.05) with (1) the percentage of the

basin having poorly drained soils (negative correlation), (2)

the percentage of a 100-meter buffer zone along the entire

stream classified as forested wetland (negative), and (3) the

percentage of the basin used for row-crop agriculture

(positive) (figs. 19, 20). Numbers of species also we

correlated with several water-chemistry variables tha

associated with these basinwide conditions, includin

(1) dissolved organic carbon (negative), (2) minimum

dissolved oxygen (positive), (3) pH (negative), and (

dissolved nitrate (positive). North Carolina Index of 

Integrity (NCIBI) scores, which are commonly used 

indicate the ecological status of the fish community 

Carolina Department of Environment, Health, and N

Resources, 1997), were related similarly to many of t

environmental variables (figs. 19, 20).

30

25

20

15

10

5

0

56

54

52

50

48

46

44

42

40

38 0 10

Number

of species

NCIBI

Score

20 30

PERCENTAGE OF BASIN AREA CLASSIFIED

AS ROW-CROP AGRICULTURE

40 50 60

NUMBER OF SPECIES 

Figure 19. Numbers of species increased in bas

having more row-crop agriculture.

30

25

20

15

10

5

0

56

54

52

50

48

46

44

42

40

38 0 20

Number 

of species

NCIBI

Score

40 60

PERCENTAGE OF 100-METER BUFFER ZONE

CLASSIFIED AS FORESTED WETLAND

80 100

NUMBER OF SPECIES

Figure 20. Areas having more forested wetlands h

lower numbers of species.
U.S. Geological Survey Circular 11

MAJOR ISSUES AND FI

Fish Comm

Although numbers of species and NCIBI scores were

correlated significantly with basinwide environmental

variables, they were not correlated significantly with reachlevel variables, such as the amount of instream cover and

substrate particle size. This result indicates that fish

community composition may be broadly determined by

basinwide environmental conditions and only secondarily by

local conditions. One implication of this is that mitigation

and restoration strategies that focus on the local scale, while

neglecting basinwide conditions, may not be fully

successful.

The relations between numbers of species, NCIBI scores,

and environmental characteristics indicated that, in general,

more species of fish and higher NCIBI scores were found in

agricultural areas with minimal wetland buffers. In fact,

richer fish communities and higher NCIBI scores tended to

occur in areas where human impacts have been

substantial—opposite of the expectation that numbers of

species, and especially NCIBI scores, should decline when

streams are affected by human activities.

This unexpected pattern may reflect natural differences in

fish community composition that are a consequence of soil

type rather than human activities. Streams located in basins

dominated by poorly drained soils generally tended to have

lower numbers of species and NCIBI scores than streams in

areas dominated by medium- or well-drained soils (fig. 21).

Yet several of the streams in areas with poorly drained soils

were among the least affected in the study area—those with

natural channels, the greatest percentage of wetland buffer,

and the smallest percentage of row-crop agriculture.

Many of the streams in areas where poorly drained,

organic-rich soils prevail cease flowing during the summer,

partly because the soil does not yield enough ground 

maintain streamflow. The most pristine streams have

extensive floodplain forests that contribute to this co

by lowering the water table through transpiration. Flo

swamps and organic-rich soils contribute large amou

particulate and dissolved organic material to these st

and when the water stops flowing, the decaying orga

material reduces the concentration of dissolved oxyg

High concentrations of dissolved organic acids also 

pH. The natural combination of quiescent water, low

dissolved oxygen concentration, and, in some cases,

extremely low pH may limit fish communities in the

to a relatively small number of species that can survi

difficult summer conditions. These include banded s

swampfish, and mud sunfish. The harsh summer con

may, in fact, act as a natural barrier to other species, 

resulting in a refugium for a distinct natural fish com

characteristic of Coastal Plain streams in areas with 

drained soils.

In contrast, streams in basins with well-drained, s

soils receive more ground-water input during summ

are, therefore, less dependent on rainfall to maintain

streamflow. They also tend to maintain higher concen

of dissolved oxygen and have a pH that is neutral or 

moderately acidic. As a result, these streams appear 

able to support a more diverse fish community that i

more minnow species and species that are associated 

flowing water, such as satinfin shiner, dusky shiner, 

shiner, and shield darter. Fish communities of uncha

streams in these areas also included many of the spe

found in the areas with poorly drained soils. Fish

communities in channelized streams in well-drained 

tended to have an even greater proportion of flowing

minnow species and often lacked the species found 

streams in areas with poorly drained soils.

The current version of the NCIBI is not calibrated 

account for natural differences in species richness an

aspects of fish community composition that are asso

with soil drainage characteristics. One way to accom

this might be to calibrate the NCIBI independently f

inner and outer Coastal Plain. The inner Coastal Pla

typically has sandy soils that drain relatively rapidly

whereas the outer Coastal Plain has many areas with

organic-rich soils that drain much more slowly (McM

and Lloyd, 1995). Calibrating NCIBI metrics separa

within each of these physiographic provinces would 

water-quality assessments account for a major comp

the natural variability in fish community structure.

Unfortunately, the data collected for this study are n

sufficient for developing and testing candidate metri

recalibrated biotic index. Data for additional stream

outer Coastal Plain are needed particularly.

Figure 21. Streams in poorly drained basins had lower

numbers of species and NCIBI scores than those basins

having well- and medium-drained soils.

WELL- AND MEDIUMDRAINED SOILSPOORLY DRAINED

SOILS

50

40

30

20

10

0

NORTH CAROLINA INDEX OF BIOTIC INTEGRITY (NCIBI) SCORE

20

18

16

14

12

10

8

6

4

2

0

NUMBER OF SPECIES

NUMBER OF SPECIES 

NCIBI SCORE
22 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

PCBs and ORGANOCHLORINE COMPOUNDS in

streambed sediments and fish tissue 

Nutrient concentrations in the southern Coastal Plain of the

basin are high compared to concentrations at other

NAWQA sites nationwide. Intensive agriculture in the

Coastal Plain, combined with wastewater-treatment

discharges and runoff from urban areas in the Piedmont,

provide major sources of nutrient concentrations in the

Neuse and Tar River Basins. Phosphorus concentrations

are particularly high in parts of the Tar and Neuse River

Basins, partly because of a geologic source.

Relatively few organochlorine compounds were detected. Of

those, DDE was the most common. Concentrations of the

detected compounds are near or above the median at several

sites when compared nationally. The highest values are

associated with small basins in areas of intensive agriculture.

Seven major water-quality characteristics were evaluated for stream si

in each NAWQA Study Unit. Summary scores for each characteristic w

computed for all sites that had adequate data. Scores for each site in th

Albemarle-Pamlico Drainage Basin were compared to scores for all si

sampled in the 20 NAWQA Study Units during 1992–95. Results are

summarized by percentiles; higher percentile values generally indicate

poorer quality compared to that of other NAWQA sites. Water-quality

conditions at each site also are compared to established criteria for

protection of aquatic life. Applicable criteria are limited to nutrients an

pesticides in water and semivolatile organic compounds, organochlori

pesticides, and PCBs in sediment. (Methods used to compute rankings 

evaluate aquatic-life criteria are described by Gilliom and others, in pr

Pesticides were present in low concentrations in m

of the surface-water samples collected; the Tar R

Basin had the highest concentrations. The herbici

metolachlor, atrazine, prometon, and alachlor we

detected in over 60 percent of the stream samples

Pesticides in surface water are indicative of exten

agriculture in the Albemarle-Pamlico Drainage B

EXPLANATION

Greater than the 75th percentile

(Among the highest 25 percent nationally)

Between the median and the 75th percentile

Between the 25th percentile and median

Less than the 25th percentile

(Among the lowest 25 percent nationally)

Ranking relative to national conditions—

Darker colored circles generally indicate

poorer quality. Bold outline of circle indicates

one or more aquatic-life criteria were

exceeded.

WATER-QUALITY CONDITIONS IN A NATIONAL CONTEXT

Comparison of Stream Quality with Nationwide NAWQA Findings

NUTRIENTS in water

PESTICIDES in water
U.S. Geological Survey Circular 11

Trace element concentrations in bed sediment at 6 of the 10

sites were above the national median. Based on 1992 sampling

of 22 sites, highest concentrations of trace elements in bed

sediment were usually associated with urban basins.

Based on stream modification, bank ero

bank stability, and riparian vegetation

density, sites in the Study Unit were

moderately to highly degraded when

compared to other sites in the Nation. T

degradation reflects the presence of

extensive and widespread channel

modifications made in past decades to

improve drainage and the presence of m

areas susceptible to bank erosion.

Fish communities in the Albemarle-Pamlico Drainage Basin were

ranked as low to moderately degraded compared to other sites

across the Nation; however, the metrics used to calculate the

national rankings may not be appropriate for assessing fish

community degradation in the Coastal Plain of North Carolina.

The four national metrics are the percentage of individual fish

belonging to species classified as (1) omnivorous, (2) non-native,

(3) tolerant to human-caused stream degradation, and (4) having

external physical anomalies.

SVOCs were generally low compared to those at other

NAWQA sites nationwide. The sites with elevated

concentrations are generally associated with urban areas.

CONCLUSIONS

Nutrient concentrations, orga

chlorine compounds, and trace

elements in sediment at many o

sites in the Albemarle-Pamlico

Drainage Basin were high comp

to those at other NAWQA sites

nationwide. The causes for the

elevated concentrations are a

combination of agricultural, urba

and natural sources.

Although stream habitats ten

to be more degraded than the

national norm, fish communities

tended to be less degraded than 

national norm. This inconsistenc

may occur because the fish

community metrics used to calcu

the national index are insensitiv

changes in fish community

composition that occur as a resu

habitat degradation in the Coast

Plain.

TRACE ELEMENTS in streambed sediments

SEMIVOLATILE ORGANIC COMPOUNDS (SVOCs) 

in streambed sediments

FISH COMMUNITIES

STREAM HABITAT

WATER-QUALITY CONDITIONS IN A NATIONAL CO

Comparison of Stream Quality with Nationwide NAWQA F
24 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

Five major water-quality characteristics were evaluated for ground-water s

in each NAWQA Study Unit. Ground-water resources were divided into 

categories: (1) drinking-water aquifers, and (2) shallow ground water unde

agricultural or urban areas. Summary scores were computed for each

characteristic for all aquifers and shallow ground-water areas that had ade

data. Scores for each aquifer and shallow ground-water area in the Albem

Pamlico Drainage Basin were compared to scores for all aquifers and sha

ground-water areas sampled in the 20 NAWQA Study Units during 1992

Results are summarized by percentiles; higher percentile values generally

indicate poorer quality compared to that of other NAWQA ground-water st

Water-quality conditions for each drinking-water aquifer also are compar

established drinking-water standards and criteria for protection of human h

(Methods used to compute rankings and evaluate standards and criteria ar

described by Gilliom and others, in press.)

Nitrate concentrations in ground water were low relative to

national conditions. However, certain areas of the AlbemarlePamlico Drainage Basin have higher concentrations than

others. The highest concentrations are associated with welldrained soils of the inner Coastal Plain. About 5 percent of

the wells in shallow aquifers of the inner Coastal Plain and

3 percent in the outer Coastal Plain exceeded the 10-mg/L

drinking-water standard (U.S. Environmental Protection

Agency, 1986).

y

yyy yy

y

y

y

@@@@ÀÀÀÀ







@

@

@







À

À

À

@

@@ÀÀ   

@@@@ @@@@ @@@@  ÀÀÀÀ ÀÀÀÀ ÀÀÀÀ

NITRATE

@À

EXPLANATION

Inner Coastal Plain

Outer Coastal Plain

Agricultural land use

Urban area

Greater than the 75th percentile

(Among the highest 25 percent nationally)

Between the median and the 75th percentile

Between the 25th percentile and median

Less than the 25th percentile

(Among the lowest 25 percent nationally)

Drinking-water aquifers

Shallow ground-water areas

Ranking relative to national conditions—

Darker colored circles generally indicate

poorer quality. Bold outline of circle indicates

one or more drinking-water standards were

exceeded.

WATER-QUALITY CONDITIONS IN A NATIONAL CONTEXT

Comparison of Ground-Water Quality with Nationwide NAWQA Findings
U.S. Geological Survey Circular 11

Pesticide detections in the agricultural areas o

Plain were among the highest nationally. Thr

or their metabolites were detected at concent

greater than 0.1 g/Lin shallow ground water. 

general, pesticides applied to crops appeared 

ground water at concentrations less than drin

standards.

Volatile organic compound detections in ground

water were among the lowest in the Nation. Only

four compounds were detected in ground water in

three wells in the Coastal Plain, and these

concentrations were below drinking-water

standards. However, these compounds may be more

common in urban areas not sampled in this study.

CONCLUSIONS

Nitrate concentrations in sha

ground water in the Coastal Pla

the Albemarle-Pamlico Drainag

Basin were among the lowest

nationally. The highest concen

trations were detected in shallo

aquifers of the inner Coastal P

Dissolved-solids concentrat

and volatile organic compound

detection rates were low comp

to those for the rest of the Nati

Frequency of detections of

herbicides and their metabolite

were among the highest nation

in agricultural areas of the oute

Coastal Plain. However, the co

centrations detected were less 

drinking-water standards for

selected herbicides.

Dissolved-solids concentrations in ground water

were among the lowest relative to national

conditions. The ground-water samples tested were

from shallow, unconsolidated sedimentary units

in the Coastal Plain, which contain relatively few

easily dissolved minerals.

y

yyy yy

y

y

y

@@@@ÀÀÀÀ







@

@

@







À

À

À

@

@@ÀÀ   

@@@@ @@@@ @@@@  ÀÀÀÀ ÀÀÀÀ ÀÀÀÀ

VOLATILE ORGANIC COMPOUNDS (VOCs)

WATER-QUALITY CONDITIONS IN A NATIONAL CO

Comparison of Ground-Water Quality with Nationwide NAWQA F

y

y

y

y

y





@

@





À

À







@@@

@@@

@@@







ÀÀÀ

ÀÀÀ

ÀÀÀ

PESTICIDES

y

yyy yy

y

y

y

@@@@ÀÀÀÀ







@

@

@







À

À

À

@

@@ÀÀ   

@@@@ @@@@ @@@@  ÀÀÀÀ ÀÀÀÀ ÀÀÀÀ

DISSOLVED SOLIDS
26 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

STUDY DESIGN AND DATA COLLECTION

35o

36o

37o

80o 79o 78o 77o 76o

20 40 60 MILES

0 20 40 60 KILOMETERS

0

North Carolina

Virginia

35o

36o

37o

80o 79o 78o 77o 76o

20 40 60 MILES

0 20 40 60 KILOMETERS

0

North Carolina

Virginia

35o

36o

37o

80o 79o 78o 77o 76o

20 40 60 MILES

0 20 40 60 KILOMETERS

0

North Carolina

Virginia

EXPLANAT

BOTTOM SEDIMEN

WATER CHEMISTR

 Fixed Sites

WATER CHEMISTR

 Fixed Sites

WATER CHEMISTR

EXPLANATIO

CONTAMINANTS IN 

INTENSIVE ECOLO

 ASSESSMENTS

ECOLOGICAL SYN

 STUDIES

EXPLANAT

AQUIFER SURVEY

LAND-USE EFFEC

MUNICIPAL WELLS

FLOW-PATH STUDY 

URBAN LAND-USE 

 AREA

1

7

8

2

4

5

6

9 3

11

10 12

STREAM ECOLOGY

STREAM CHEMISTRY

GROUND-WATER

CHEMISTRY

SITE SITE

NUMBER NAME

1 Albemarle Canal at Swindell, N.C.

2 Bear Creek near Mays Store,

N.C.

3 Blackwater River at Franklin, Va.

4 Chicod Creek near Simpson, N.C.

5 Contentnea Creek at Hookerton,

N.C.

6 Devil’s Cradle Creek near Alert,

N.C.

7 Durham Creek at Edward, N.C.

8 Neuse River at Kinston, N.C.

9 Nottoway River near Sebrell, Va.

10 Pete Mitchell Swamp near Penny

Hill, N.C.

11 Tar River at Tarboro, N.C.

12 Van Swamp at Hoke, N.C.
U.S. Geological Survey Circular 11

STUDY DESIGN AND DATA COLL

SUMMARY OF DATA COLLECTION IN THE ALBEMARLE-PAMLICO STUDY UNIT, 1992–95

Study

component

What data were collected

and why Types of sites sampled Numberof sites

 Sam

frequ

and p

Stream Chemistry

Bottom-sediment survey Determine presence of potentially toxic

compounds attached to sediments in

major streams.

Sample depositional zones at selected sites basinwide for trace elements and hydrophobic

organic compounds.

22 

(in 1

Water chemistry—

Basic Fixed Sites

Describe concentrations and loads of

chemicals, suspended sediment, and

nutrients at selected sites basinwide.

Sample at or near sites where streamflow is

measured continuously for major ions, organic

carbon, suspended sediment, and nutrients.

12 ~12 pe

3 y

Water chemistry—

Intensive Fixed Sites

Determine concentration and timing of

agriculture-related compounds that run

off to streams.

Subset of basinwide chemistry stations where 80

pesticides are sampled at least monthly and

during selected runoff events.

4 ~25 in 

~ 7 in 

Water chemistry—

Synoptic sites

Describe seasonal occurrence and spatial

distribution of contamination over broad

areas and how well the chemistry

stations represent the entire basin.

Sample streams for pesticides and(or) nutrients,

major ions, suspended sediment, organic

carbon, and streamflow.

66 1–6 in 

per

Stream Ecology

Contaminants in tissues Determine occurrence and distribution of

contaminants that can accumulate in

tissues of aquatic organisms.

Collect and analyze Asiatic clams (Corbicula

fluminea) and redbreast sunfish (Lepomis

auritus) for trace elements and organochlorine

compounds.

19 

(in 1

Intensive ecological

assessments

Assess in detail biological communities

and habitat representing selected

environmental settings.

Sample and quantify fish, macroinvertebrates, and

algae at a subset of the water chemistry basic

sites; quantitatively describe stream habitat for

these organisms; replicate sampling over three

stream reaches at four sites.

7 1–2 in 

per

Ecological synoptic

studies

Determine presence and community

structure of aquatic species and habitat

in representative streams across the

basin.

Sample and quantify fish and(or)

macroinvertebrates and(or) algae, and describe

habitat at selected water-chemistry sites in the

Coastal Plain.

46 1–2 in 

per

Ground-Water Chemistry

Aquifer survey Describe the overall water quality and

natural chemical patterns in aquifers.

Sample wells within the shallow aquifers of the

Coastal Plain for major ions, nutrients,

pesticides, volatile organic compounds, trace

elements, and radionuclides; six deep

municipal wells sampled in areas of significant

drawdown.

35 

Land-use effects Determine the effects of specific land use

on the quality of shallow ground water.

Sample shallow wells in corn and soybean areas

for major ions, nutrients, pesticides, and

volatile organic compounds, (some wells

sampled only for nitrate, atrazine, and related

compounds). Sample wells in urban area,

Virginia Beach, Va., for major ions, nutrients,

pesticides, and volatile organic compounds.

52 

Flow-path study Describe land-use effects on surficial

aquifers along ground-water flow from

areas of recharge beneath the land use to

discharge to a stream.

Sample clusters of wells installed along an

approximate line of ground-water flow and at

various depths within the surficial aquifers for

land-use effects of corn and soybean

cultivation; analyze for major ions, nutrients,

and pesticides; volatile organic compounds and

age-dating constituents analyzed once at some

wells.

27 ~4 pe
28 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

Herbicide

(Trade or common

name)

Rate

of

detection b

Concentration, in μg/L

0.001 0.01 0.1 1 10 100 1,000

The following tables summarize data dollected for NAWQA studies from 1992 to 1995 by showing results for the Albemarle-Pam

Study Unit compared to the NAWQA national range for each compound detected. The data were collected at a wide variety of places an

order to represent the wide concentration ranges observed among Study Units, logarithmic scales are used to emphasize the general mag

centrations (such as 10, 100, or 1,000), rather than the precise number. The complete dataset used to construct these tables is available u

The rate of detection for ground water in this table may differ from the rate reported in text because all wells sampled are included here 

wells throughout the Coastal Plain are referred to in text discussion.

Concentrations of herbicides, insecticides, volatile organic compounds, and nutrients detected in ground and surface water

Albemarle-Pamlico Drainage Study Unit. [mg/L, milligrams per liter; μg/L, micrograms per liter; pCi/L, picocuries per liter; %

<, less than; - -, not measured; trade names may vary]

EXPLANATION

Range of surface-water detections in all 20 Study Units

Detection in the Albemarle-Pamlico Drainage Study Unit

Range of ground-water detections in all 20 Study Units

Drinking water standard or guideline a

Freshwater-chronic criterion for the protection of aquatic life a

Herbicide

(Trade or common

name)

Rate

of

detection b

Concentration, in μg/L

0.001 0.01 0.1 1 

Metribuzin (Lexone,

Sencor)

20%

1%

Molinate (Ordram) <1%

0%

Napropamide

(Devrinol)

16%

0%

Pebulate (Tillam) <1%

0%

Pendimethalin

(Prowl, Stomp)

5%

0%

Prometon (Gesagram, prometone)

59%

4%

Pronamide (Kerb,

propyzamid)

<1%

0%

Propachlor (Ramrod,

propachlore)

<1%

0%

Propanil (Stampede,

Surcopur)

<1%

0%

Simazine (Aquazine,

Princep, GEsatop)

32%

<1%

Tebuthiuron (Spike,

Perflan)

22%

1%

Terbacilc (Sinbar) <1%

<1%

Thiobencarb (Bolero,

Saturn, benthiocarb)

<1%

0%

Triallate (Far-Go) <1%

0%

Trifluralin (Treflan,

Trinin, Elancolan)

4%

0%

SUMMARY OF COMPOUND DETECTIONS AND CONCENTRATIONS

Acifluorfen (Blazer,

Tackle 2S)

1%

0%

Alachlor (Lasso) 63%

<1%

2,6-Diethylaniline

(Alachlor metabolite)

1%

4%

Atrazine (AAtrex,

Gesaprim)

70%

6%

Deethylatrazinec

(Atrazine metabolite)

9%

4%

Benfluralin (Balan,

Benefin, Bonalan)

<1%

0%

Butylate (Sutan,

Genate Plus, butilate)

1%

0%

Cyanazine (Bladex,

Fortrol)

10%

0%

2,4-D (2,4-PA) 0%

1%

DCPA (Dacthal,

chlorthal-dimethyl)

1%

0%

EPTC (Eptam) 1%

0%

Ethalfluralin (Sonalan,Sonalen)

<1%

0%

Fluometuron (FloMet, Cotoran)

8%

3%

Linuron (Lorox,

Linex)

4%

0%

Metolachlor (Dual,

Pennant)

80%

7%
U.S. Geological Survey Circular 1157 

Aldicarbc (Temik) 1%

0%

Aldicarb sulfonec

(Standak)

0%

2%

Aldicarb sulfoxidec

(Aldicarb metabolite)

0%

3%

Azinphos-methylc

(Guthion, Gusathion)

<1%

0%

Carbarylc (Sevin,

Savit)

19%

<1%

Carbofuranc

(Furadan, Curaterr)

7%

2%

Chlorpyrifos (Dursban, Lorsban)

5%

<1%

p,p’-DDE (p,p’-DDT

metabolite)

<1%

<1%

Diazinon 8%

7%

Dieldrin (Panoram D31, Octalox)

1%

1%

Ethoprop (Mocap,

Prophos)

2%

0%

Fonofos (Dyfonate) 2%

0%

gamma-HCH 2%

0%

Malathion (maldison,

malathon, Cythion)

2%

0%

cis-Permethrinc

(Ambush, Pounce)

<1%

0%

Phorate (Thimet,

Rampart)

2%

0%

Propargite (Comite,

Omite, BPPS)

1%

0%

Terbufos (Counter) <1%

0%

Volatile organic

compound

(Trade or common

name)

Rate

of

detection b

Concentration, in μg/L

1,2,4-Trimethylbenzene (Pseudocumene)

--

1%

1,3,5-Trimethylbenzene (Mesitylene)

--

1%

Chlorobenzene

(Monochlorobenzene)

--

2%

0.01 0.1 1 10 100 1,000

Chloroethene (Vinyl

Chloride)

--

1%

Dimethylbenzenes

(Xylenes (total))

--

1%

Ethylbenzene (Phenylethane)

--

1%

Isopropylbenzene

(Cumene)

--

1%

Methylbenzene (Toluene)

--

1%

Naphthalene --

1%

total Trihalomethanes --

1%

Trichlorofluoromethane (CFC 11)

--

1%

n-Propylbenzene

(Isocumene)

--

1%

Volatile organic

compound

(Trade or common

name)

Rate

of

detection b

Concentration, in μg/L

Methyl tert-butyld

ether (MTBE)

--

1%

Nutrient

(Trade or common

name)

Rate

of

detection b

Concentration, in mg/L

Dissolved ammonia 95%

96%

Dissolved ammonia

plus organic nitrogen

as nitrogen

96%

67%

Dissolved phosphorus as phosphorus

81%

53%

Dissolved nitrite plus

nitrate

83%

52%

Other Rate

of

detection b

Concentration, in pCi/L

Radon 222 --

80%

0.01 0.1 1 10 100 

0.01 0.1 1 10 100 

1 10 100 1,000 

Volatile organic

compound

(Trade or common

name)

Rate

of

detection b

Concentration, in μg/L

0.01 0.1 1 10 

Insecticide

(Trade or common

name)

Rate

of

detection b

Concentration, in μg/L

0.001 0.01 0.1 1 10 100 1,000

SUMMARY OF COMPOUND DETECTIONS AND CONCE
30 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

Herbicides, insecticides, volatile organic compounds, and nutrients not detected in ground and surface waters of the Albem

Drainage Study Unit.

Herbicides

2,4,5-T

2,4,5-TP (Silvex, Fenoprop)

2,4-DB (Butyrac, Butoxone, Embutox Plus, Embutone)

Acetochlor (Harness Plus,

Surpass)

Bentazon (Basagran, Bentazone, Bendioxide)

Bromacil (Hyvar X, Urox

B, Bromax)

Bromoxynil (Buctril, Brominal)

Chloramben (Amiben,

Amilon-WP, Vegiben)

Clopyralid (Stinger, Lontrel, Reclaim, Transline)

Dacthal mono-acid (Dacthal

metabolite)

Dicamba (Banvel, Dianat,

Scotts Proturf)

Dichlorprop (2,4-DP, Seritox 50, Kildip, Lentemul)

Dinoseb (Dinosebe)

Diuron (Crisuron, Karmex,

Direx, Diurex)

Fenuron (Fenulon, Fenidim)

MCPA (Rhomene, Rhonox,

Chiptox)

MCPB (Thistrol)

Neburon (Neburea, Neburyl, Noruben)

Norflurazon (Evital, Predict, Solicam, Zorial)

Oryzalin (Surflan, Dirimal)

Picloram (Grazon, Tordon)

Propham (Tuberite)

Triclopyr (Garlon, Grandstand, Redeem, Remedy)

Insecticides

3-Hydroxycarbofuran (Carbofuran metabolite)

Disulfoton (Disyston, DiSyston, Frumin AL,

Solvirex, Ethylthiodemeton)

Methiocarb (Slug-Geta,

Grandslam, Mesurol)

Methomyl (Lanox, Lannate, Acinate)

Methyl parathion (PenncapM, Folidol-M, Metacide,

Bladan M)

Oxamyl (Vydate L, Pratt)

Parathion (Roethyl-P, Alkron, Panthion, Phoskil)

Propoxur (Baygon, Blattanex, Unden, Proprotox)

alpha-HCH (alpha-BHC,

alpha-lindane, alphahexachlorocyclohexane,

alpha-benzene hexachloride)

Volatile organic

compounds

1,1,1,2-Tetrachloroethane

(1,1,1,2-TeCA)

1,1,1-Trichloroethane

(Methylchloroform)

1,1,2,2-Tetrachloroethane

1,1,2-Trichloro-1,2,2-trifluoroethane (Freon 113,

CFC 113)

1,1,2-Trichloroethane

(Vinyl trichloride)

1,1-Dichloroethane (Ethylidene dichloride)

1,1-Dichloroethene

(Vinylidene chloride)

1,1-Dichloropropene

1,2,3-Trichlorobenzene

(1,2,3-TCB)

1,2,3-Trichloropropane

(Allyl trichloride)

1,2,4-Trichlorobenzene

1,2-Dibromo-3-chloropropane (DBCP, Nemagon)

1,2-Dibromoethane (EDB,

Ethylene dibromide)

1,2-Dichlorobenzene (oDichlorobenzene, 1,2-

DCB)

1,2-Dichloroethane (Ethylene dichloride)

1,2-Dichloropropane (Propylene dichloride)

1,3-Dichlorobenzene (mDichlorobenzene)

1,3-Dichloropropane (Trimethylene dichloride)

1,4-Dichlorobenzene (pDichlorobenzene, 1,4-

DCB)

1-Chloro-2-methylbenzene (o-Chlorotoluene)

1-Chloro-4-methylbenzene (p-Chlorotoluene)

2,2-Dichloropropane

Benzene

Bromobenzene (Phenyl

bromide)

Bromochloromethane

(Methylene chlorobromide)

Bromomethane (Methyl

bromide)

Chloroethane (Ethyl chloride)

Chloromethane (Methyl

chloride)

Dibromomethane (Methylene dibromide)

Dichlorodifluoromethane

(CFC 12, Freon 12)

Dichloromethane (Methylene chloride)

Ethenylbenzene (Styrene)

Hexachlorobutadiene

Tetrachloroethene (Perchloroethene)

Tetrachloromethane (Carbon tetrachloride)

Trichloroethene (TCE)

cis-1,2-Dichloroethene

((Z)-1,2-Dichloroethene)

cis-1,3-Dichloropropene

((Z)-1,3-Dichloropropene)

n-Butylbenzene (1-Phenylbutane)

p-Isopropyltoluene (pCymene)

sec-Butylbenzene

tert-Butylbenzene

trans-1,2-Dichloroethene

((E)-1,2-Dichlorothene)

trans-1,3-Dichloropropene

((E)-1,3-Dichloropropene)

Nutrients

No non-dete

SUMMARY OF COMPOUND DETECTIONS AND CONCENTRATIONS
U.S. Geological Survey Circular 1157 

1,6-Dimethylnaphthalene

--

5%

1-Methyl-9H-fluorene --

5%

1-Methylphenanthrene

--

9%

1-Methylpyrene --

14%

2,2-Biquinoline --

9%

2,3,6-Trimethylnaphthalene

--

5%

2,6-Dimethylnaphthalene

--

27%

2-Ethylnaphthalene --

5%

2-Methylanthracene --

9%

4,5-Methylenephenanthrene

--

14%

9H-Carbazole --

18%

9H-Fluorene --

5%

Acenaphthylene --

18%

Acridine --

23%

Anthracene --

18%

Anthraquinone --

32%

Benz[ a ]anthracene --

27%

Concentrations of semivolatile organic compounds, organochlorine compounds, and trace elements detected in fish and cla

bed sediment of the Albemarle-Pamlico Drainage Study Unit. [μg/g, micrograms per gram; μg/kg, micrograms per kilogram

<, less than; - -, not measured; trade names may vary]

EXPLANATION

Range of detections in fish and clam tissue in all 20 Study Units

Detection in bed sediment or fish tissue in the Albemarle-Pamlico Drainage Study Unit

Range of detections in bed sediment in all 20 Study Units

Guideline for the protection of aquatic life e

Detection in clam tissue in the Albemarle-Pamlico Drainage Study Unit

Semivolatile organic

compound

Rate of

detection b

Concentration, in μg/kg

0.1 10 100 1,000 10,000 100,000 1

Semivolatile organic

compound

Rate of

detection b

Concentration, in μg/kg

0.1 10 100 1,1

Benzo[ a ]pyrene --

32%

Benzo[ b ]fluoranthene

--

36%

Benzo[ c ]cinnoline --

5%

Benzo[ ghi ]perylene --

23%

Benzo[ k ]fluoranthene

--

36%

Butylbenzylphthalate --

55%

Chrysene --

36%

Di- n -butylphthalate --

100%

Di- n -octylphthalate --

5%

Dibenz[ a,h ]

anthracene

--

14%

Dibenzothiophene --

5%

Diethylphthalate --

50%

Dimethylphthalate --

18%

Fluoranthene --

45%

Indeno[1,2,3- cd ]

pyrene

--

27%

Isoquinoline --

9%

Naphthalene --

5%

SUMMARY OF COMPOUND DETECTIONS AND CONCE
32 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

Phenanthrene --

32%

Phenol --

68%

Pyrene --

36%

bis(2-Ethylhexyl)phthalate

--

100%

p-Cresol --

9%

Organochlorine

compound

(Trade name)

Rate

of

detection b

Concentration, in μg/kg

total-Chlordane 20%

9%

p,p’-DDE 52%

50%

total-DDT 52%

50%

Dieldrin (Panoram D31, Octalox)

12%

14%

Endosulfan I (alphaendosulfan, Thiodan)

--

5%

PCB, total 8%

0%

Toxaphene (camphechlor, Hercules)

4%

0%

0.01 0.1 1 10 100 1,000 10,000 100,000

Arsenic 70%

100%

Cadmium 93%

100%

Chromium 100%

100%

Copper 100%

100%

Lead 13%

100%

Mercury 97%

100%

Nickel 90%

100%

Selenium 90%

100%

Zinc 100%

100%

Semivolatile organic

compound

Rate of

detection b

Concentration, in μg/kg

0.1 10 100 1,000 10,000 100,000 1

Trace element Rate

of

detection b

Concentration, in μg/g

0.01 0.1 1 10 1

SUMMARY OF COMPOUND DETECTIONS AND CONCENTRATIONS
U.S. Geological Survey Circular 1157 

Semivolatile organic compounds, organochlorine compounds, and trace elements not detected in fish and clam tissue and b

of the Albemarle-Pamlico Drainage Study Unit.

Semivolatile organic

compounds

1,2,4-Trichlorobenzene

1,2-Dichlorobenzene

(o-Dichlorobenzene,

1,2-DCB)

1,2-Dimethylnaphthalene

1,3-Dichlorobenzene

(m-Dichlorobenzene)

1,4-Dichlorobenzene

(p-Dichlorobenzene,

1,4-DCB)

2,4-Dinitrotoluene

2,6-Dinitrotoluene

2-Chloronaphthalene

2-Chlorophenol

3,5-Dimethylphenol

4-Bromophenyl-phenylether

4-Chloro-3-methylphenol

4-Chlorophenyl-phenylether

Acenaphthene

Azobenzene

C8-Alkylphenol

Isophorone

N-Nitrosodi-n-propylamine

N-Nitrosodiphenylamine

Nitrobenzene

Pentachloronitrobenzene

Phenanthridine

Quinoline

bis (2-Chloroethoxy)methane

Organochlorine

compounds

Aldrin (HHDN, Octalene)

Chloroneb (chloronebe,

Demosan, Soil Fungicide

1823)

DCPA (Dacthal, chlorthaldimethyl)

Endrin (Endrine)

Heptachlor epoxide (Heptachlor metabolite)

Heptachlor (Heptachlore,

Velsicol 104)

Hexachlorobenzene (HCB)

Isodrin (Isodrine, Compound 711)

Mirex (Dechlorane)

Pentachloroanisole (PCA,

pentachlorophenol metabolite)

alpha-HCH (alpha-BHC,

alpha-lindane, alphahexachlorocyclohexane,

alpha-benzene hexachloride)

beta-HCH (beta-BHC,

beta-hexachlorocyclohexane, alpha-benzene

hexachloride)

cis-Permethrin (Ambush,

Astro, Pounce, Pramex,

Pertox, Ambushfog, Kafil,

Perthrine, Picket, Picket G,

Dragnet, Talcord, Outflank,

Stockade, Eksmin, Coopex,

Peregin, Stomoxin, Stomoxin P, Qamlin, Corsair,

Tornade)

delta-HCH (delta-BHC,

delta-hexachlorocyclohexane, delta-benzene

hexachloride)

gamma-HCH (Lindane,

gamma-BHC, Gammexane, Gexane, Soprocide,

gamma-hexachlorocyclohexane, gamma-benzene

hexachloride)

o,p’-Methoxychlor

p,p’-Methoxychlor (Marlate, methoxychlore)

trans-Permethrin (Ambush,

Astro, Pounce, Pramex,

Pertox, Ambushfog, Kafil,

Perthrine, Picket, Picket G,

Dragnet, Talcord, Outflank,

Stockade, Eksmin, Coopex,

Peregin, Stomoxin, Stomoxin P, Qamlin, Corsair,

Tornade)

Trace elem

No non-detec

a

 Selected water-quality standards and guidelines (Gilliom, Mueller, and Nowell, in press).

b Rates of detection are based on the number of analyses and detections in the Study Unit, not on national data. Rates of detection for h

insecticides were computed by only counting detections equal to or greater than 0.01 μg/L in order to facilitate equal comparisons 

pounds, which had widely varying detection limits. For herbicides and inseticides, a detection rate of “<1%” means that all detecti

0.01 μg/L, or the detection rate rounds to less than one percent. For other compound groups, all detections were counted and minim

its for most compounds were similar to the lower end of the national ranges shown. Method detection limits for all compounds in t

summarized in Gilliom, Mueller, and Nowell (in press).

c

 Detections of these compounds are reliable, but concentrations are determined with greater uncertainty than for the other compounds 

as estimated values (Zaugg and others, 1995).

d The guideline for methyl tert-butyl ether is between 20 and 40 μg/L; if the tentative cancer classification C is accepted, the lifetime he

be 20 μg/L (Gilliom, Mueller, and Nowell, in press).

e

 Selected sediment-quality guidelines (Gilliom, Mueller, and Nowell, in press).

SUMMARY OF COMPOUND DETECTIONS AND CONCE
34 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

REFERENCES

Burkholder, J.M., 1997, Stimulation of the toxic dinoflagellate,

Pfiesteria piscicida, by nutrient enrichment, in Forum on

proceedings of the Albemarle-Pamlico Estuarine Study

Comprehensive Conservation and Management Plan

Implementation, New Bern, N.C., June 5–6, 1997: Raleigh,

N.C., Department of Environment and Natural Resources.

Cunningham, P.A., Williams, R.E., Chessin, R.L., McCarthy, J.M.,

Curry, R.J., Gold, K.W., Pratt, R.W., and Stichter, S.J., 1992,

Watershed planning in the Albemarle-Pamlico estuarine

system, Report 3—Toxics analysis: Research Triangle Park,

N.C, Research Triangle Institute Report No. 92–04, 171 p.

Gilliam, J.W., Osmond, D.L., and Evans, R.O., 1997, Selected

agricultural best management practices to control nitrogen in

the Neuse River Basin: Raleigh, North Carolina State

University, North Carolina Agricultural Research Service

Technical Bulletin 311, 53 p.

Gilliom, R.J., Mueller, D.K., and Nowell, L.H., in press, Methods

for comparing water-quality conditions among National

Water-Quality Assessment Study Units, 1992–95: U.S.

Geological Survey Open-File Report 97–589.

Gilmore, C.C., 1995, Mercury methylation in fresh waters, in

Proceedings of the National Forum on Mercury in Fish, New

Orleans, La., Sept. 27–29, 1994: U.S. Environmental

Protection Agency, EPA 823–R–95–002, p. 23–29.

Harned, D.A., and Davenport, M.S., 1990, Water-quality trends and

basin activities and characteristics for the Albemarle-Pamlico

estuarine system, North Carolina and Virginia: U.S.

Geological Survey Open-File Report 90–398, 164 p.

Harned, D.A., McMahon, Gerard, Spruill, T.B., and Woodside,

M.D., 1995, Water-quality assessment of the AlbemarlePamlico Drainage Basin, North Carolina and

Virginia—Characterization of suspended sediment, nutrients,

and pesticides: U.S. Geological Survey Open-File Report 95–

191, 131 p.

Long, E.R., and Morgan, L.G., 1991, The potential for biological

effects of sediment-sorbed contaminants tested in the national

status and trends program: Seattle, Wash., National Oceanic

and Atmospheric Administration, NOAA Technical

Memorandum NOS OMA 52, 175 p.

Mackenthum, K.M., 1969, The practice of water pollution biology:

Washington, D.C., Federal Water Pollution Control

Administration, 281 p.

McMahon, Gerard, and Lloyd, O.B., Jr., 1995, Water-quality

assessment of the Albemarle-Pamlico Drainage Basin, North

Carolina and Virginia—Environmental setting and waterquality issues: U.S. Geological Survey Open-File Report 95–

136, 72 p.

McMahon, Gerard, and Woodside, M.D., 1997, Nutrient mass

balance for the Albemarle-Pamlico Drainage Basin, North

Carolina and Virginia, 1990: Journal of the American Water

Resources Association, v. 33, no. 3, p. 573–589.

Meador, M.R., Cuffney, T.F., and Gurtz, M.E., 1993, Methods for

sampling fish communities as part of the National WaterQuality Assessment Program: U.S. Geological Survey OpenFile Report 93–104, 40 p.

Mueller, D.K., Hamilton, P.A., Helsel, D.R., Hitt, K.J., and Ruddy,

B.C., 1995, Nutrients in ground water and surface water of the

United States—An analysis of data through 1992: U.S.

Geological Survey Water-Resources Investigations Report 95–

4031, 74 p.

National Technical Advisory Committee, 1968, Water qual

Federal Water Pollution Control Administration, 234 

North Carolina Department of Environment, Health, and N

Resources, 1997, Fish community structure, in Standa

operating procedures—Biological monitoring: Divisio

Quality, Water Quality Section Ecosystems Analysis 

18–27.

Nowell, L.H., and Resek, E.A., 1994, Summary of nationa

and guidelines for pesticides in water, bed sediment, a

organisms and their application to water-quality asses

U.S. Geological Survey Open-File Report 94–44, 115 

Paller, M.H., 1994, Relationships between fish assemblage 

and stream order in South Carolina Coastal Plain stre

Transactions of the American Fisheries Society, v. 12

161.

Peterson, M.J., Southworth, G.R., and Ham, K.D., 1994, E

sublethal chlorinated discharges on PCB accumulatio

transplanted Asiatic clams (Corbicula fluminea): Wate

Soil Pollution, no. 73, p. 169–178.

Ruhl, P.M., and Smith, K.E., 1996, Water-quality assessme

Albemarle-Pamlico Drainage Basin, North Carolina a

Virginia—Trace elements in Asiatic clam (Corbicula 

soft tissue and redbreast sunfish (Lepomis auritus) liv

93: U.S. Geological Survey Open-File Report 96–334

Skrobialowski, S.C., 1996, Water-quality assessment of the

Albemarle-Pamlico Drainage Basin, North Carolina a

Virginia—A summary of selected trace element, nutri

pesticide data for bed sediments, 1969-90: U.S. Geolo

Survey Water-Resources Investigations Report 96–41

Smith, K.E., and Ruhl, P.M.,1996, Water-quality assessme

Albemarle-Pamlico Drainage Basin, North Carolina a

Virginia—Organochlorine compounds in Asiatic clam

(Corbicula fluminea) soft tissue and whole redbreast 

(Lepomis auritus), 1992–93: U.S. Geological Survey 

Report 96–201, 6 p.

Spruill, T.B., Eimers, J.L., and Morey, A.E. , 1996, Nitrate

concentrations in shallow ground water of the Coasta

the Albemarle-Pamlico Drainage Study Unit, North C

and Virginia: U.S. Geological Survey Fact Sheet FS–2

4 p.

U.S. Environmental Protection Agency, 1986, Quality crite

water: Washington D.C., U.S. Government Printing O

440/5–86–001.

———1992, National study of chemical residues in fish:

Washington, D.C., U.S. Environmental Protection Ag

v. 1, 828–R–92–008a.

Vollenweider, R.A., 1971, Scientific fundamentals of the

eutrophication of lakes and flowing waters, with parti

reference to nitrogen and phosphorus as factors in

eutrophication: Paris, France, Organization for Econo

Cooperation and Development, 193 p.

Woodside M.D., and Simerl, B.R., 1996, Water-quality ass

the Albemarle-Pamlico Basin, North Carolina and

Virginia—Chemical analyses of organic compounds a

inorganic constituents in streambed sediment, 1992–9

Geological Survey Open-File Report 96–103, 25 p.

Zaugg, S.D., Sandstrom, M.W., Smith, S.G., and Fehlberg

1995, Methods of analysis by the U.S. Geological Sur

National Water Quality Laboratory—Determination o

pesticides in water by C-18 solid-phase extraction and 

column gas chromatography/mass spectrometry with 

ion monitoring: U.S. Geological Survey Open-File Re

95-181, 49 p.
U.S. Geological Survey Circular 11

GLO

Algae—Chlorophyll-bearing nonvascular, primarily aquatic

species that have no true roots, stems, or leaves; most algae

are microscopic, but some species can be as large as

vascular plants.

Aquatic-life criteria—Water-quality guidelines for protection

of aquatic life. Often refers to U.S. Environmental

Protection Agency water-quality criteria for protection of

aquatic organisms. See also Water-quality guidelines,

Water-quality criteria, and Freshwater chronic criteria.

Aquifer—A water-bearing layer of soil, sand, gravel, or rock

that will yield usable quantities of water to a well.

Base flow—Sustained, low flow in a stream; ground-water

discharge is the source of base flow in most places.

Basic Fixed Sites—Sites on streams at which streamflow is

measured and samples are collected for temperature,

salinity, suspended sediment, major ions and metals,

nutrients, and organic carbon to assess the broad-scale

spatial and temporal character and transport of inorganic

constituents of streamwater in relation to hydrologic

conditions and environmental settings.

Basin—See Drainage basin.

Bed sediment—The material that temporarily is stationary in

the bottom of a stream or other watercourse.

Bioaccumulation—The biological sequestering of a substance

at a higher concentration than that at which it occurs in the

surrounding environment or medium. Also, the process

whereby a substance enters organisms through the gills,

epithelial tissues, dietary, or other sources.

Breakdown product—A compound derived by chemical,

biological, or physical action upon a pesticide. The

breakdown is a natural process which may result in a more

toxic or a less toxic compound and a more persistent or

less persistent compound.

Channelization—Modification of a stream, typically by

straightening the channel, to provide more uniform flow;

often done for flood control or for improved agricultural

drainage or irrigation.

Community—In ecology, the species that interact in a common

area.

Concentration—The amount or mass of a substance present in

a given volume or mass of sample. Usually expressed as

microgram per liter (water sample) or micrograms per

kilogram (sediment or tissue sample).

Degradation products—Compounds resulting from

transformation of an organic substance through chemical,

photochemical, and(or) biochemical reactions.

Denitrification—A process by which oxidized forms of

nitrogen such as nitrate (NO3

–

) are reduced to form

nitrites, nitrogen oxides, ammonia, or free nitrogen:

commonly brought about by the action of denitrifying

bacteria and usually resulting in the escape of nitrogen to

the air.

Discharge—Rate of fluid flow passing a given point at 

moment in time, expressed as volume per unit of 

Dissolved solids—Amount of minerals, such as salt, th

dissolved in water; amount of dissolved solids is a

indicator of salinity or hardness.

Drainage basin—The portion of the surface of the Ear

contributes water to a stream through overland ru

including tributaries and impoundments.

Fertilizer—Any of a large number of natural or synthe

materials, including manure and nitrogen, phospho

potassium compounds, spread on or worked into 

increase its fertility.

Fixed Sites—NAWQA's most comprehensive monitor

See also Basic Fixed Sites and Intensive Fixed Sit

Flow path—An underground route for ground-water

movement, extending from a recharge (intake) zo

discharge (output) zone such as a shallow stream.

Freshwater chronic criteria—The highest concentrat

contaminant that freshwater aquatic organisms ca

exposed to for an extended period of time (4 days) 

adverse effects. See also Water-quality criteria.

Ground water—In general, any water that exists bene

land surface, but more commonly applied to wate

saturated soils and geologic formations.

Habitat—The part of the physical environment where 

and animals live.

Herbicide—A chemical or other agent applied for the 

of killing undesirable plants. See also Pesticide.

Index of Biotic Integrity (IBI)—An aggregated numb

index, based on several attributes or metrics of a fi

community that provides an assessment of biolog

conditions.

Indicator sites—Stream sampling sites located at outl

drainage basins with relatively homogeneous land 

physiographic conditions; most indicator-site basi

drainage areas ranging from 20 to 200 square mil

Integrator or Mixed-use site—Stream sampling site l

an outlet of a drainage basin that contains multipl

environmental settings. Most integrator sites are o

streams with relatively large drainage areas.

Intensive Fixed Sites—Basic Fixed Sites with increas

sampling frequency during selected seasonal peri

analysis of dissolved pesticides for 1 year. Most N

Study Units have one to two integrator Intensive F

Sites and one to four indicator Intensive Fixed Sit

Load—General term that refers to a material or constit

solution, in suspension, or in transport; usually ex

in terms of mass or volume.

Median—The middle or central value in a distribution 

ranked in order of magnitude. The median is also k

the 50th percentile.

Metabolite—A substance produced in or by biologica

processes.

The terms in this glossary were compiled from numerous sources. Some definitions have been modified and ma

the only valid ones for these terms.
36 Water Quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992–95

GLOSSARY

Micrograms per liter ( g/L)—A unit expressing the

concentration of constituents in solution as weight

(micrograms) of solute per unit volume (liter) of water;

equivalent to one part per billion in most streamwater and

ground water. One thousand micrograms per liter equals

1 mg/L.

Milligrams per liter (mg/L)—A unit expressing the

concentration of chemical constituents in solution as

weight (milligrams) of solute per unit volume (liter) of

water; equivalent to one part per million in most

streamwater and ground water. One thousand micrograms

per liter equals 1 mg/L.

Nonpoint source—A pollution source that cannot be defined as

originating from discrete points such as pipe discharge.

Areas of fertilizer and pesticide applications, atmospheric

deposition, manure, and natural inputs from plants and

trees are types of nonpoint-source pollution.

Pesticide—A chemical applied to crops, rights of way, lawns,

or residences to control weeds, insects, fungi, nematodes,

rodents, or other "pests."

Point source—A source at a discrete location such as a

discharge pipe, drainage ditch, tunnel, well, concentrated

livestock operation, or floating craft.

Point-source contaminant—Any substance that degrades

water quality and originates from discrete locations such

as discharge pipes, drainage ditches, wells, concentrated

livestock operations, or floating craft.

Refugium—An area that has escaped ecological changes

occurring elsewhere and so provides a suitable habitat for

relict species.

Sediment—Particles, derived from rocks or biological

materials, that have been transported by a fluid or other

natural process, and are suspended or settled in water.

Sorption—General term for the interaction (binding or

association) of a solute ion or molecule with a solid.

Species diversity—An ecological concept that incorporates

both the number of species in a particular sampling area

and the evenness with which individuals are distributed

among the various species.

Species (taxa) richness—The number of species (taxa) present

in a defined area or sampling unit.

Specific conductance—A measure of the ability of a liquid to

conduct an electrical current.

Study Unit—A major hydrologic system of the United States in

which NAWQA studies are focused. Study Units are

geographically defined by a combination of ground- and

surface-water features and generally encompass more than

4,000 square miles of land area.

Study-Unit Survey—Broad assessment of the water-q

conditions of the major aquifer systems of each S

Unit. The Study-Unit Survey relies primarily on s

existing wells and, wherever possible, on existing 

collected by other agencies and programs. Typica

30 wells are sampled in each of three to five aquif

subunits.

Synoptic sites—Sites sampled during a short-term inve

of specific water-quality conditions during selecte

seasonal or hydrologic conditions to provide impr

spatial resolution for critical water-quality conditi

Tolerant species—Those species that are adaptable to 

of) human alterations to the environment and ofte

increase in number when human alterations occur

Trace element—An element found in only minor amo

(concentrations less than 1.0 milligram per liter) i

or sediment; includes arsenic, cadmium, chromiu

copper, lead, mercury, nickel, and zinc.

Triazine herbicide—A class of herbicides containing 

symmetrical triazine ring (a nitrogen-heterocyclic 

composed of three nitrogens and three carbons in 

alternating sequence). Examples include atrazine,

propazine, and simazine.

Volatile organic compounds (VOCs)—Organic chem

have a high vapor pressure relative to their water s

VOCs include components of gasoline, fuel oils, 

lubricants, as well as organic solvents, fumigants, 

inert ingredients in pesticides, and some by-produ

chlorine disinfection.

Water-quality criteria—Specific levels of water qualit

if reached, are expected to render a body of water

unsuitable for its designated use. Commonly refer

water-quality criteria established by the U.S.

Environmental Protection Agency. Water-quality 

are based on specific levels of pollutants that wou

the water harmful if used for drinking, swimming

farming, fish production, or industrial processes.

Water-quality guidelines—Specific levels of water qu

which, if reached, may adversely affect human he

aquatic life. These are nonenforceable guidelines i

a governmental agency or other institution.

Water-quality standards—State-adopted and U.S.

Environmental Protection Agency-approved ambi

standards for water bodies. Standards include the 

the water body and the water-quality criteria that 

met to protect the designated use or uses.
Spruill and others • Water Quality in the Albemarle-Pamlico Drainage

USGS Circular 1157 • 1998

National Water-Quality Assessment (NAWQA) Program

Albemarle-Pamlico Drainage Basin

NAWQA

Raleigh

NORTH CAROLINA

VIRGINIA

Roanoke Rive

Ta

r

r Rive

N

r

euse River