Water Quality in the Santee River Basin

and Coastal Drainages

North and South Carolina, 1995–98

U.S. Department of the Interior

U.S. Geological Survey

Circular 1206
POINTS OF CONTACT AND ADDITIONAL INFORMATION

Front cover: Edisto River near Givhans, South Carolina.

Back cover: Left—Surface-water sampling, Indian Creek, North Carolina; Middle—Fish identification, Jacob Fork 

River, North Carolina. 

All photographs in this report were taken by members of the Santee River Basin and coastal drainages Study Unit, 

U.S. Geological Survey.

The companion Web site for NAWQA Study Unit summary reports:

http://water.usgs.gov/nawqa/

Santee River Basin and coastal drainages contact and Web site:

USGS State Representative

U.S. Geological Survey

Water Resources Division

Stephenson Center, Suite 129

720 Gracern Road

Columbia, SC 29210-7651

e-mail: msdavenp@usgs.gov

http://sc.water.usgs.gov/nawqa/santhome.html

River Basin Assessments

Albemarle-Pamlico Drainage Basin (Circular 1157)

Allegheny and Monongahela River Basins (Circular 1202)

Apalachicola-Chattahoochee-Flint River Basin (Circular 1164)

Central Arizona Basins (Circular 1213)

Central Columbia Plateau (Circular 1144)

Central Nebraska Basins (Circular 1163)

Connecticut, Housatonic and Thames River Basins (Circular 1155)

Eastern Iowa Basins (Circular 1210)

Georgia-Florida Coastal Plain (Circular 1151)

Hudson River Basin (Circular 1165)

Kanawha-New River Basins (Circular 1204)

Lake Erie-Lake Saint Clair Drainages (Circular 1203)

Las Vegas Valley Area and the Carson and Truckee River Basins

(Circular 1170)

Lower Illinois River Basin (Circular 1209)

Long Island-New Jersey Coastal Drainages (Circular 1201)

Lower Susquehanna River Basin (Circular 1168)

Mississippi Embayment (Circular 1208)

Ozark Plateaus (Circular 1158)

Potomac River Basin (Circular 1166)

Puget Sound Basin (Circular 1216)

Other NAWQA summary reports

Red River of the North Basin (Circular 1169)

Rio Grande Valley (Circular 1162)

Sacramento River Basin (Circular 1215)

San Joaquin-Tulare Basins (Circular 1159)

South-Central Texas (Circular 1212) 

South Platte River Basin (Circular 1167)

Southern Florida (Circular 1207)

Trinity River Basin (Circular 1171)

Upper Colorado River Basin (Circular 1214) 

Upper Mississippi River Basin (Circular 1211)

Upper Snake River Basin (Circular 1160)

Upper Tennessee River Basin (Circular 1205)

Western Lake Michigan Drainages (Circular 1156)

White River Basin (Circular 1150)

Willamette Basin (Circular 1161)

National Assessments

The Quality of Our Nation‘s Waters—Nutrients and Pesticides (Circular 1225)

National NAWQA Program:

Chief, NAWQA Program

U.S. Geological Survey

Water Resources Division

12201 Sunrise Valley Drive, M.S. 413

Reston, VA 20192

http://water.usgs.gov/nawqa/
U.S. GEOLOGICAL SURVEY CIRCULAR

Water Quality in the Santee River Basin and 

Coastal Drainages, North and South Carolina, 

1995–98

1206

By W. Brian Hughes, Thomas A. Abrahamsen, Terry L. Maluk, Eric J. Reuber, and 

Lance J. Wilhelm
Library of Congress Cataloging-in-Publications Data

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

Or call: 1-888-ASK-USGS

U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

2000

Water-quality assessment of the Santee River Basin and coastal drainages, North and South Carolina, 1995–98 

/ by W. Brian Hughes...[et al.].

p. cm. -- (U.S. Geological Survey Circular ; 1206)

Includes bibliographical references.

ISBN 0-607-95422-1 (alk. paper)

1. Water quality--South Carolina--Santee River Watershed. 2. Water quality--North Carolina. I. Hughes, W. 

Brian. II. Geological Survey (U.S.) III. Series.

TD224.S6 W384 2000

363.739’42’097578--dc21

00-049461
CONTENTS

Contents III

NATIONAL WATER-QUALITY ASSESSMENT PROGRAM.................................................................................IV

SUMMARY OF MAJOR FINDINGS ......................................................................................................................1

Stream and River Highlights...........................................................................................................................1

Ground-Water Highlights ................................................................................................................................2

INTRODUCTION TO THE SANTEE RIVER BASIN AND COASTAL DRAINAGES .............................................3

Physiography and Water Quality ....................................................................................................................3

Land Use and Water Quality...........................................................................................................................3

Climate Conditions and Water Quality............................................................................................................4

Water Use.......................................................................................................................................................4

Flow Regulation, Impoundments, and Surface-Water Quality ........................................................................5

Aquifer Characteristics and Ground-Water Quality.........................................................................................5

MAJOR FINDINGS ...............................................................................................................................................6

Pesticides Commonly Were Detected in Santee Basin Streams....................................................................6

Few Pesticides Were Detected in Drinking-Water Supply Aquifers ................................................................7

Pesticides Were Common in Shallow Ground Water in Urban and Agricultural Areas...................................8

Organochlorine Pesticides Were Detected in Bed Sediment and Tissues .....................................................8

NATIONAL PERSPECTIVE—Santee Basin Pesticide Findings Were Similar to National Findings...............9

Phosphorus Concentrations in Streams Frequently Exceeded USEPA Goals .............................................10

Water-Supply Aquifers Rarely Exceeded Drinking-Water Standards for Nitrate...........................................11

NATIONAL PERSPECTIVE—Phosphorus Concentrations in the Santee Basin Were

in the Middle Range of National Results ..................................................................................................13

Bed Sediment Had Low Concentrations of Trace Elements .........................................................................14

NATIONAL PERSPECTIVE—Mercury Contamination Potential in Santee Basin Was Highest in Nation....14

Trace Elements Accumulated in Clam Tissue and Fish Livers .....................................................................15

Radon Exceeded Proposed Standards in Many Wells.................................................................................16

NATIONAL PERSPECTIVE—Radon Concentrations Were High in the Santee Basin ................................16

Volatile Organic Compounds Were Common in Urban Ground Water.........................................................17

Drinking-Water Aquifers Had Low Concentrations of Volatile Organic Compounds.....................................18

Urban and Agricultural Streams Had High Concentrations of Bacteria ........................................................19

Biological Communities Reflected Land-Use Differences ............................................................................20

NATIONAL PERSPECTIVE—Santee Basin Streams were in the Middle of National Biological Rankings..21

STUDY UNIT DESIGN........................................................................................................................................22

GLOSSARY ........................................................................................................................................................24

REFERENCES....................................................................................................................................................25

APPENDIX—WATER-QUALITY DATA FROM THE SANTEE RIVER BASIN AND COASTAL DRAINAGES

IN A NATIONAL CONTEXT ................................................................................................................................26
NATIONAL WATER-QUALITY ASSESSMENT PROGRAM

IV National Water-Quality Assessment Program 

1991–95

1994–98

1997–2001

Not yet scheduled

High Plains Regional

Ground Water Study, 

1999-2004

NAWQA Study Units— 

Assessment schedule

Santee River Basin

and coastal drainages

THIS REPORT summarizes major findings about water quality in the Santee River Basin and coastal drainages 

that emerged from an assessment conducted between 1995 and 1998 by the U.S. Geological Survey (USGS) 

National Water-Quality Assessment (NAWQA) Program. Water quality is discussed in terms of local and regional 

issues and compared to conditions found in all 36 NAWQA study areas, called Study Units, assessed to date. 

Findings are also explained in the context of selected national benchmarks, such as those for drinking-water quality 

and the protection of aquatic organisms. The NAWQA program was not intended to assess the quality of the 

Nation’s drinking water, such as by monitoring water from household taps. Rather, the assessments focus on the 

quality of the resource itself, thereby complementing many ongoing Federal, State, and local drinking-water 

monitoring programs. The comparisons made in this report to drinking-water standards and guidelines are only in 

the context of the available untreated resource. Finally, this report includes information about the status of aquatic 

communities and the condition of in-stream habitats as elements of a complete water-quality assessment.

Many topics covered in this report reflect the concerns of officials of State and Federal agencies, water-resource 

managers, and members of stakeholder groups who provided advice and input during the Santee River Basin and 

coastal drainages assessment. Basin residents who wish to know more about water quality in the areas where they 

live will find this report informative as well. 

THE NAWQA PROGRAM seeks to improve scientific and public understanding of water quality in the Nation’s 

major river basins and ground-water systems. Better understanding facilitates effective resource management, 

accurate identification of water-quality priorities, and successful development of strategies that protect and restore 

water quality. Guided by a nationally consistent study design and shaped by ongoing communication with local, 

State, and Federal agencies, NAWQA assessments support the investigation of local issues and trends while 

providing a firm foundation for understanding water quality at regional and national scales. The ability to integrate 

local and national scales of data collection and analysis is a unique feature of the USGS NAWQA Program.

The Santee River Basin and coastal drainages is one of 51 water-quality assessments initiated since 1991, when 

the U.S. Congress appopriated funds for the USGS to begin the NAWQA Program. As indicated on the map, 36 

assessments have been completed, and 15 more assessments will conclude in 2001. Collectively, these assessments 

cover about one-half of the land area of the United States and include water resources that are available to more 

than 60 percent of the U.S. population.
Summary of Major Findings 1 

SUMMARY OF MAJOR FINDINGS

Stream and River Highlights

Surface water sampled in the Santee River 

Basin and coastal drainages generally meets 

existing Federal and State guidelines for 

drinking-water quality and protection of 

aquatic life. However, urban and agricultural 

land uses have affected water quality, as 

indicated by elevated concentrations of 

bacteria, pesticides, and nutrients in basins 

dominated by these land uses.

• The herbicides atrazine, simazine, and tebuthiuron were detected in almost every stream in the 

Santee Basin, including those in forested areas, at 

levels below aquatic-life and drinking-water 

guidelines. Four insecticides—malathion, diazinon, chlorpyrifos, and parathion—exceeded 

aquatic-life guidelines. No pesticides exceeded 

drinking-water standards, though 7 of the 30 

compounds detected do not have drinking-water 

standards and 13 do not have aquatic guidelines. 

Pesticide concentrations had seasonal patterns, 

The Santee River Basin and coastal drainages (the “Santee 

Basin”) is an approximately 24,000-square-mile area in North and 

South Carolina that encompasses the Blue Ridge Mountains, the 

Piedmont, and the Coastal Plain (Fenneman, 1946). Most of the 

3.5 million people in the Santee Basin live in urban areas. Eightysix percent of the water used in homes and for industry is treated 

surface water withdrawn from rivers or reservoirs. Ground water is 

the main water source for rural households.

Piedmont

Coastal

Plain

0 50 KILOMETERS

0 50 MILES

Edisto R

N. Fork

S. Fork

Saluda R

Enoree R

Tyger R

Catawba R

Wateree R

Santee R

Broad R

Columbia NORTH

CAROLINA

SOUTH

CAROLINA

Santee

Basin

Blue

Ridge

GreenvilleSpartanburg

Charlotte

Charleston

WATER-QUALITY SAMPLING IN

THE SANTEE RIVER BASIN

AND COASTAL DRAINAGES

EXPLANATION

STREAM-WATER SAMPLING SITE

GROUND-WATER SAMPLING AREAS

Piedmont aquifer

Sandhills aquifers

Agricultural study and Floridan aquifer

Columbia urban study

Cow Castle Creek flow-path study

North Carolina

South Carolina

Cooper R 35°

36°

82° 81°

36°

35°

34°

82°

33°

34°

80°

33°

81°

80°

Selected Indicators of Stream-Water Quality

Small Streams Major Rivers

Urban

Agricultural

Undeveloped/

Forest

Mixed

Land Uses

Pesticides

Bacteria

contact recreation; or above a national goal for preventing excess

recreation; or below a national goal for preventing excess algal growth

Nutrients

Trace

elements

Organochlorines

Volatile

organics

Semivolatile

organics

2

3

4

5

7

Total phosphorus and nitrate (as nitrogen), sampled in water.

Arsenic, mercury, and metals, sampled in sediment.

Organochlorine compounds including DDT and PCB's, sampled in sediment.

Solvents, refrigerants, fumigants, and gasoline compounds, sampled in water.

Miscellaneous industrial chemicals and combustion by-products, sampled in sediment.

Percentage of samples with concentrations equal to or greater than a health-related national guideline for drinking water,aquatic life, or

Percentage of samples with concentrations less than a health-related

national guideline for drinking water, aquatic life, or water-contact

Percentage of samples with no detection

Not assessed

~

~

~ Insufficient data

~

~

algal growth

6Fecal coliform bacteria, sampled in water.

1

Insecticides, herbicides, and pesticide metabolites, sampled in water.

1

2

3

4

5

6

7

with the highest concentrations measured in the spring following application.

• Nitrate concentrations did not exceed drinking-water 

standards in any streams sampled. Average total phosphorus 

concentrations in four streams were above the U.S. 

Environmental Protection Agency (USEPA) recommended 

goal to prevent nuisance aquatic growth. The South Fork 

Catawba River had an average total phosphorus concentration 

that was four times higher than the USEPA goal and is a 

significant source of phosphorus to downstream lakes. 

Wastewater discharge and agricultural runoff are major 

sources of nitrogen and phosphorus.

• Trace metals were detected frequently in bed sediment and 

tissue, mostly at concentrations within aquatic-life guidelines. 

Arsenic, chromium, and lead exceeded guidelines in a few 

samples. Although concentrations were not high in sediment 

samples, data suggest that mercury is accumulating in fish 

and clams in concentrations that are harmful to humans or 

animals that eat them. Sampling by State agencies has 
2 Water Quality in the Santee River Basin and Coastal Drainages

Selected Indicators of Ground-Water Quality

Shallow Ground Water Water-Supply Aquifer

Urban Agricultural Piedmont Sandhills Floridan

Pesticides

Percentage of samples with concentrations equal to or

greater than health-related national guidelines for drinking water

Percentage of samples with concentrations less than

health-related national guidelines for drinking water

Percentage of samples with no detection 

Not assessed

Nitrate

Radon

Volatile

organics 4

1

Insecticides, herbicides, and pesticide metabolites, sampled in water.

3

2

1

2

Nitrate (as nitrogen), sampled in water.

3

Radon, sampled in water.

4

Solvents, refrigerants, fumigants, and gasoline compounds, sampled in water.

resulted in fish-consumption advisories for mercury in 49 rivers 

and reservoirs in South Carolina.

• Organochlorine pesticides were detected frequently in bed 

sediment and tissue. Most of these compounds have been 

discontinued for use for many years but continue to be detected 

because they are persistent in the environment. A derivative of 

DDT was detected at concentrations exceeding aquatic-life 

standards in sediment at three agricultural sites.

• Volatile organic compounds (VOCs) known to occur in the aquifer adjacent to Gills Creek, an urban stream in Columbia, S.C., 

were frequently detected in the creek as well. Although no existing Federal or State drinking-water standards or aquatic guidelines were exceeded, this finding is consistent with the 

important influence of ground-water quality on stream-water 

quality.

• Bacteria levels frequently exceeded South Carolina standards for 

contact recreation in streams in forested, urban, and agricultural 

areas. Standards were exceeded more frequently in small 

streams than in large rivers.

• Biological communities in urban and agricultural streams had 

fewer species of fish and invertebrates that can tolerate contamination than forested and mixed land-use streams. This suggests 

that contaminants resulting from these land uses affect the natural communities that live in these areas, although factors such as 

habitat alteration can cause similar changes in biological communities.

Ground-Water Highlights

Ground water in the Santee Basin generally meets existing Federal and State standards for drinking water except 

with respect to nitrate, which failed to meet the drinkingwater standard in almost one-half of the shallow monitoring 

wells sampled in agricultural areas, and radon, which did 

not meet proposed standards in about one-half the drinkingwater wells sampled basinwide. Pesticides were detected 

frequently in urban, agricultural, and drinking-water supply 

wells, but only two samples exceeded drinking-water standards. Many wells contained low concentrations of numerous synthetic chemicals related to industry, household use, 

and motor vehicles, and a few of these chemicals were at 

levels above drinking-water standards.

• Pesticides were detected in 17 of 90 wells sampled in drinkingwater supply aquifers. Of the 34 detected, only 2 pesticides 

exceeded drinking-water standards, but 11 of the detected 

pesticides do not have standards. Most wells in agricultural and 

urban areas contained at least one pesticide, but only two wells 

in urban areas had concentrations that exceeded drinking-water 

standards.

• Nitrate is the only nutrient that was detected in 

significant concentrations in ground water, and it 

exceeded drinking-water standards in almost one-half 

of the shallow monitoring wells in agricultural areas. 

Although this finding indicates significant 

contamination of shallow ground water, most 

drinking-water wells are located in deeper aquifers. 

Nitrate in the Piedmont and Sandhills aquifers was 

elevated above natural concentrations but exceeded 

standards in only two wells. The Floridan aquifer, 

which is protected for the most part by confining units 

in the study area, had relatively low concentrations of 

nitrate.

• Radon, a naturally occurring radioactive gas, was 

detected in almost all wells sampled in drinking-water 

aquifers. Over one-half of the wells had 

concentrations that exceeded proposed Federal 

drinking-water standards. Most of the wells with 

radon concentrations that exceeded the proposed 

standard are located in the Piedmont aquifer.

• VOCs were detected in 27 of 30 monitoring wells in 

an urban setting. Most compounds were detected at 

extremely low levels; however, the concentrations of 

trichloroethylene, a solvent, and methyl tert-butyl 

ether, a gasoline additive, were above a drinkingwater standard and an advisory level, respectively, in 

one well each. Fifteen of the 35 compounds detected 

do not have drinking-water standards. VOCs in 

drinking-water supply aquifers were detected 

throughout the Santee Basin, but no concentrations 

exceeded drinking-water standards.
Introduction to the Santee River Basin and Coastal Drainages 3

INTRODUCTION TO THE SANTEE RIVER BASIN AND COASTAL 

DRAINAGES

COLUMBIA

CHARLOTTE

GREENVILLE-

 SPARTANBURG

CHARLESTON

North Carolina

South Carolina

0 50 100 KILOMETERS

0 50 100 MILES

EXPLANATION

URBAN OR BUILT-UP

AGRICULTURAL

RANGELAND

FORESTED

WATER

WETLAND

STUDY UNIT BOUNDARY

The Santee River Basin and 

coastal drainages includes about 

24,000 square miles in North and 

South Carolina. The Santee River 

has the second largest drainage 

area in the Eastern United States, 

and its basin makes up 70 percent 

of the study area. The basins of the 

Cooper, Edisto, and numerous 

smaller rivers make up the remainder of the study area.Throughout 

this report, the study area, including these smaller river basins, will 

be collectively referred to as the 

“Santee Basin.”

Physiography and Water 

Quality

The rugged mountains of the 

Blue Ridge physiographic province 

are sparsely populated. Land-use 

effects on water quality are minimal because the area is largely 

undeveloped. Consequently, the 

Blue Ridge has more pristine water 

quality and intact stream ecosystems than other parts of the study 

area.

The rolling hills and abundant 

water resources of the Piedmont 

have attracted industrial development and human population 

growth. Many of the areas experiencing urban growth are in the 

Piedmont, near the headwaters of 

rivers that supply drinking water 

and also receive treated waste 

water. Since flows in these headwater streams are smaller than they 

are farther along the stream 

courses, they have a limited capacity to assimilate large quantities of 

wastewater and nonpoint-source 

inputs from the urban areas.

The flat-lying topography and 

fertile soils of the Coastal Plain are 

ideal for agricultural use. Development for shipping, industry, and 

tourism is mostly limited to land 

within a few miles of the coast. 

Most of the Coastal Plain is characterized by slow-moving, low-gradient streams that commonly are 

bordered by extensive swamps 

(Smock and Gilinsky, 1992). The 

combination of slow-moving water 

and large quantities of organic matter in the swamps results in a characteristically dark-colored water 

called “blackwater.” Under natural 

conditions, blackwater streams 

have low pH and contain low concentrations of dissolved oxygen. 

These conditions can make the 

stream particularly susceptible to 

water-quality degradation by the 

contribution of oxygen-consuming 

chemicals in wastewater discharge 

or nonpoint contamination.

Land Use and Water Quality

The Santee Basin has a rapidly 

growing population of about 3.5 

million people. Most of the people 

live in the urban areas of Charlotte, 

N.C., and Greenville-Spartanburg, 

Columbia, and Charleston, S.C. 

(fig. 1). The most common types of 

urban development are commercial 

and residential.

As urban areas develop, 

increased use of pesticides and fertilizers on lawns and landscaped 

areas can lead to increased concentrations of these chemicals in 

ground and surface waters. Commercial and residential use of solvents and fuel products can result 

in their introduction to ground and 

Figure 1. Land use in the Santee Basin includes about 60 percent forested, 30 

percent agricultural, and 6 percent urban lands.
4 Water Quality in the Santee River Basin and Coastal Drainages

surface water through accidental 

spills or leaking storage tanks. Bacteria and nutrients can enter water 

through leaking sewer lines, malfunctioning septic tanks, and from 

runoff of pet and waterfowl wastes. 

Although thoroughly regulated, 

discharges from wastewater treatment plants increase as population 

grows, increasing the loading of 

nutrients to streams.

Agriculture is an important economic activity throughout the Santee Basin. Row crop agriculture is 

most common in the Coastal Plain, 

where corn, soybeans, and cotton 

are the most common crops (South 

Carolina Agricultural Statistics 

Service, 1999). Pasture for hay and 

for grazing cattle is typical of agricultural land in the Piedmont. 

These agricultural activities can 

result in elevated nutrient and pesticide levels in streams and ground 

water from runoff or infiltration of 

manure, fertilizer, or pesticides.

Most of the land in the Santee 

Basin is forested. Forests range 

from largely unaltered hardwoods 

in the Blue Ridge and mixed pine 

and hardwood stands in the Piedmont to intensively managed pine 

plantations and forested wetlands 

in the Piedmont and Coastal Plain. 

Trees are commercially harvested 

in all of these areas, producing various levels of soil disturbance, erosion, and increased sediment loads 

in the streams.

Climate Conditions and 

Water Quality

The major climatic factors 

affecting water quality are seasonal 

and areal distributions of precipitation. The amount of rainfall affects 

water quality because areas with 

higher rainfall generally have 

greater runoff and more infiltration 

to ground water. However, 

increased flows also can help to 

dilute concentrations of chemicals 

in ground water and surface water. 

The distribution of rainfall in the 

Santee Basin is fairly uniform 

except for very high precipitation 

in the Blue Ridge (South Carolina 

Water Resources Commission, 

1983; fig. 2).

Seasonal variability of rainfall 

also is important. Generally the 

highest concentrations of pesticides 

in streams occur when rainfall 

immediately follows pesticide 

applications. Rainfall is highest in 

spring and summer, typically when 

agricultural and residential lawn 

pesticides are applied.

Rainfall also is important 

because it contains nutrients and 

metals that contribute to concentrations of these compounds in surface water. Atmospheric deposition 

accounts for the majority of ammonia and nitrate nitrogen in streams 

(Maluk and others, 1998). A study 

also has suggested that mercury 

contamination in the Santee Basin 

results from atmospheric deposition (Krabbenhoft and others, 

1999).

Water Use

Most of the 7 billion gallons of 

water used each day in the Santee 

Basin is surface water (fig. 3). 

About 85 percent of this water is 

used in the production of electricity, and the remainder is used for 

public water supplies, commercial 

and industrial uses, irrigation of 

crops, and watering livestock. 

Ground water accounts for only 

about 14 percent of total water use 

but is a very important resource. 

Private domestic wells are the only 

Figure 2. Precipitation affects water 

quality by producing runoff to streams 

and infiltration to aquifers.

SURFACE-WATER USE IN 1995 GROUND-WATER USE IN 1995

PUBLIC SUPPLY

DOMESTIC SUPPLY

COMMERCIAL AND INDUSTRIAL

IRRIGATION AND LIVESTOCK

THERMOELECTRIC

EXPLANATION

(86 percent) (14 percent)

Figure 3. Most water used in the Santee Basin is supplied by surface water. Ground 

water is important because it is the major source of domestic water supply in rural 

areas. Relative size of pie charts represents relative percentage water use.

LINE OF EQUAL

AVERAGE ANNUAL

PRECIPITATION

EXPLANATION 50

60

70

80

50

50
Introduction to the Santee River Basin and Coastal Drainages 5 

viable sources of water in areas not 

served by public water supplies.

Flow Regulation, Impoundments, and Surface-Water 

Quality

The regulation of flow in the 

Santee Basin has altered the historical seasonal flow patterns in the 

rivers. High peak flows and 

extreme low flows downstream 

from major reservoirs generally are 

less common than they were prior 

to construction of the reservoirs. 

The alteration of flow primarily 

affects the physical habitat of the 

rivers and also can affect stream 

temperature. Populations of aquatic 

organisms are altered due to 

changed conditions in the streams 

downstream from reservoirs. For 

example, cold water discharged 

from the bottom of Lake Murray 

makes it possible for trout to survive nearly 100 miles beyond their 

normal range.

Reservoirs are especially 

affected by stream chemistry 

because they trap sediment and the 

phosphorus that attaches to the sediment. This trapping process can 

cause lakes to become eutrophic, or 

nutrient enriched, and cause algal 

blooms. Occasionally, fishkills 

result when the artificially large 

algal population dies and the dissolved oxygen, which is necessary 

for fish survival, is consumed during the decaying process. Of 11 

major lakes in the study area, 9 

contained areas with “excessive 

nutrients, extremely high productivity” and were “susceptible to 

nuisance macrophyte growth and 

algal blooms” (Stecker and 

Crocker, 1991).

Aquifer Characteristics and 

Ground-Water Quality

Shallow ground water (generally 

less than 50 feet below land 

surface) is vulnerable to 

contamination in much of the 

Santee Basin. Fertilizers, 

pesticides, and spills or leaks of 

chemicals at or near the land 

surface can move rapidly to the 

water table. Areas with sandy soils 

are particularly susceptible to 

contamination because these 

coarse-grained soils allow rapid 

transport and provide little 

opportunity for filtration or 

degradation of contaminants. 

Sandy soils typically are present in 

parts of the Coastal Plain and to a 

lesser degree in the Piedmont.

Deep aquifers also can be 

susceptible to contamination, 

depending on their degree of 

connection to the surface. The 

Piedmont, Sandhills, and Floridan 

aquifers supply most of the ground 

water in the Santee Basin (fig. 4). 

Ground water in the Piedmont 

aquifer occurs in fractures or 

cracks in the hard crystalline 

bedrock. In most areas, the bedrock 

is overlain by clay soils of variable 

thickness. Sandhills aquifers are 

unconfined; that is, they have no 

clay layer above them to inhibit the 

downward movement of 

contaminants to the aquifer. The 

Floridan aquifer is confined toward 

the coast but is unconfined farther 

inland. Of the three aquifers, the 

Sandhills aquifer is the most 

susceptible to contamination 

because of its sandy soils and lack 

of confinement. The Floridan 

aquifer, near the coast, is the least 

susceptible because it is confined.

Middendorf aquifer

Cape Fear aquifer

Black Creek aquifer

Floridan aquifer

Sandhills aquifers

Piedmont aquifer

Tertiary sand aquifer

Surficial aquifer

Not to scale

CONFINING UNIT

EXPLANATION

North Carolina

Study

Area

South

Carolina Line of section A

A'

A

A'

Figure 4. Aquifers sampled in the Santee Basin include the surficial, Piedmont, Sandhills, and Floridan aquifers (modified from

Aucott and others, 1987). The Black Creek, Middendorf, and Cape Fear aquifers are not used much in the study area because of 

the cost of drilling deep wells and poor water quality. 
6 Water Quality in the Santee River Basin and Coastal Drainages

MAJOR FINDINGS

DIAZINON

SIMAZINE

PROMETON

ATRAZINE

ALACHLOR

TEBUTHIURON

URBAN AGRICULTURAL

0

20

40

60

80

100

CHLORPYRIFOS

MALATHION

CARBARYL

METOLACHLOR

DIAZINON

SIMAZINE

PROMETON

ATRAZINE

ALACHLOR

TEBUTHIURON

CHLORPYRIFOS

MALATHION

CARBARYL

METOLACHLOR

INSECTICIDES

HERBICIDES

PERCENTAGE OF SAMPLES WITH DETECTION

EXPLANATION

Pesticides Commonly Were 

Detected in Santee Basin 

Streams

Thirty pesticides, including 22 

herbicides and 8 insecticides, were 

detected in streams in the Santee 

Basin (Maluk and Kelley, 1998). 

Of the 161 surface-water samples 

collected, 141 contained at least 

one pesticide. At least one pesticide was detected at all of the sites, 

including forested sites that have 

little influence from humans. 

Although detections were frequent, concentrations tended to be 

low, with no herbicides and only 

four insecticides and one metabolite exceeding aquatic-life criteria. 

None of the pesticide concentrations exceeded drinking-water 

standards. Thirteen of the 30 pesticides detected do not have aquatic 

criteria and 7 do not have drinkingwater standards (U.S. Environmental Protection Agency, 1996).

Herbicides were the most commonly detected pesticides in 

streams. Atrazine, an herbicide 

used on corn as well as turfgrasses 

and golf courses, was detected at 

the most sites, occurring at 11 of 

the 13 sampling sites. Other frequently detected herbicides were 

simazine, metolachlor, and prometon.Tebuthiuron, an herbicide that 

generally is used to control weeds 

on highway and railroad rights-ofway, also was detected frequently.

Insecticides were detected much 

less frequently than herbicides, 

accounting for less than one-third 

of the pesticides detected. Most 

insecticides detected are used on 

agricultural and ornamental crops, 

lawns, livestock, and in homes and 

gardens. Those most commonly 

detected included chlorpyrifos, 

diazinon, malathion, and carbaryl. 

Urban Streams Contain More 

Pesticides than Other Streams

Pesticides were detected more 

frequently in urban streams than in 

agricultural streams (fig. 5). The 

most commonly detected herbicides—simazine, prometon, atrazine, and tebuthiuron—were 

detected nearly twice as frequently 

in water samples collected at urban 

sites than at agricultural sites. Conversely, some herbicides such as 

metolachlor and alachlor were 

detected almost exclusively at agricultural sites.

Insecticides were detected about 

four times more frequently at urban 

stream sites than at agricultural 

stream sites, and aquatic-life criteria were exceeded in nine samples 

collected at urban sites and in three 

samples collected at agricultural 

sites. The insecticide diazinon was 

detected only in urban streams, 

whereas chlorpyrifos was detected 

frequently in both urban and agricultural streams. This agrees with 

national findings in which insecticides were detected more frequently in urban than in 

Figure 5. Pesticides, particularly insecticides, were detected more frequently in

urban streams than in agricultural streams.

Insecticides were detected most frequently in urban streams,

such as Gills Creek in Columbia, S.C.
Major Findings 7 

0

5

10

15

20

25

30

Floridan Piedmont Sandhills

 NONE

DETECTED

AQUIFERS SAMPLED

NUMBER OF PESTICIDES DETECTED

agricultural streams (U.S. Geological Survey, 1999).

These findings indicate that 

while agricultural activities contribute pesticides to surface water, 

concentrations are rarely high 

enough to affect aquatic life. The 

consequences of urban and suburban use of pesticides is much more 

significant, with concentrations of 

insecticides frequently at levels that 

can affect aquatic life. 

Pesticides Showed Seasonal 

Patterns in Streams

Some herbicides showed patterns of occurrence that can be 

related to seasonal applications and 

weather patterns. At Gills Creek, 

an urban stream, concentrations of 

herbicides, such as atrazine, 

simazine, and tebuthiuron, peaked 

in the spring following application 

and gradually decreased over the 

summer (fig. 6). Atrazine and 

simazine followed a similar pattern at Cow Castle Creek, an agricultural stream, with the addition 

of a second peak in early fall. The 

highest concentrations at all sites 

were observed during storms that 

followed applications.

Understanding these patterns of 

occurrence is important because 

sampling programs need to be 

designed so that critical periods of 

high pesticide concentrations are 

monitored. This information also 

can be used by environmental managers to assess risk associated with 

agricultural chemical use.

Few Pesticides Were 

Detected in Drinking-Water 

Supply Aquifers

Of the 90 drinking-water, industrial, and irrigation supply wells 

sampled in the Floridan, Piedmont, 

and Sandhills aquifers, 17 had 

detectable concentrations of pesticides; of those, only two wells had 

pesticide concentrations that 

exceeded USEPA drinking-water 

standards (U.S. Environmental Protection Agency, 1996). Eleven of 

the 34 pesticides detected in drinking-water supply aquifers did not 

have water-quality standards.

The Sandhills aquifers are more 

susceptible to contamination than 

the other aquifers, as is illustrated 

by the larger number of pesticides 

detected and the higher detection 

frequency in the Sandhills aquifers 

than in the Piedmont and Floridan 

aquifers (fig.7). In addition, the two 

wells that had pesticide concentrations exceeding USEPA drinkingwater standards were located in the 

Sandhills aquifers. Drinking water 

obtained from the Piedmont and 

Floridan aquifers is probably 

unlikely to contain pesticides at 

harmful levels; however, the high 

rate of detection and large number 

of pesticides detected in the Sandhills aquifers are a cause for concern. 

Figure 6. Herbicide concentrations 

generally peaked following spring 

applications in Gills Creek, an urban 

stream.

Figure 7. The large number of pesticides detected in the Sandhills aquifers 

illustrates its relatively high susceptibility to contamination.

Ground-water samples are pumped directly into a mobile laboratory for processing samples and conducting field analyses.
8 Water Quality in the Santee River Basin and Coastal Drainages

0

10

20

30

40

50

60

PERCENTAGE OF SAMPLES WITH

 PESTICIDE DETECTIONS

URBAN AGRICULTURAL

The differences in the rate and 

number of detections in the aquifers may be related to differences 

in aquifer properties. The Sandhills 

are largely composed of layers of 

coarse and fine sand with various 

quantities of clay. No continuous 

confining unit or soil layer overlies 

the aquifer to impede the movement of contaminants into ground 

water. At the other extreme, the 

Floridan aquifer has an overlying 

clay confining layer that impedes 

vertical movement of contaminants throughout much of its extent 

(Aucott and others, 1987). The 

Piedmont aquifer has an overlying 

layer of weathered bedrock that 

contains abundant clay. The thickness of this unit is highly variable, 

but generally it impedes rapid vertical movement of contaminants 

from land surface to ground water. 

Pesticides Were Common in 

Shallow Ground Water in 

Urban and Agricultural Areas

Pesticides were detected in 24 of 

30 shallow wells in urban areas and 

in 22 of 30 wells in agricultural 

areas (Reuber, 1999). Dieldrin concentrations exceeded drinkingwater standards in four urban 

wells; however, the wells sampled 

were installed for monitoring purposes only and are not drinkingwater supply wells. Dieldrin also 

exceeded aquatic-life standards in 

these four urban wells, and tebuthiuron concentrations exceeded 

aquatic-life standards in one agricultural well. Generally, groundwater concentrations are not compared to aquatic-life standards; 

however, these concentrations can 

be of concern because shallow 

ground water can discharge to 

streams, elevating the pesticide 

concentrations in surface water.

Pesticides were detected in 

ground water in urban areas about 

twice as frequently as in agricultural areas (fig. 8). Some pesticides 

detected in urban and agricultural 

ground water were the same, 

although insecticides were detected 

more frequently in urban ground 

water. This was similar to national 

NAWQA findings. The insecticide 

most frequently detected at urban 

sites was dieldrin. Although its 

agricultural use was canceled in the 

mid-1970s, dieldrin (and aldrin, 

which breaks down to dieldrin) was 

used for termite control until the 

mid-1980s and is a persistent compound (Barbash and Resek, 1996). 

Dieldrin was also the most commonly detected pesticide in urban 

ground water nationally (U.S. Geological Survey, 1999).

Organochlorine Pesticides 

Were Detected in Bed 

Sediment and Tissues

Fourteen pesticides were 

detected in streambed-sediment 

samples, and 21 of 24 sites sampled had at least one detectable 

pesticide. All of the pesticides 

detected in sediment were 

organochlorine insecticides, such 

as chlordane, dieldrin, mirex, and 

DDT and its derivatives. Many of 

these compounds had their agricultural uses cancelled more than 20 

years ago, yet they still appear in 

sediment samples. The reason for 

this is because the compounds are 

persistent, or are highly resistant to 

chemical breakdown. 

Of the compounds detected, only 

DDE, a breakdown product of 

DDT, exceeded guidelines for the 

protection of aquatic life. The 

guidelines were exceeded at three 

sites, all of which are in basins with 

a high percentage of agricultural 

land. In addition, DDT concentrations were only slightly below the 

aquatic guidelines at several sites. 

Comparisons of land use to concentrations of organochlorine pesticides generally did not show strong 

relations, primarily because these 

insecticides were used in both 

urban and agricultural settings 

(fig. 9). The only prominent relaFigure 8. Pesticides were detected 

more frequently at urban ground-water 

sites than at agricultural sites.

Shallow wells for the urban ground-water 

study were installed by the U.S. Geological Survey with assistance from the 

South Carolina Geological Survey.
Major Findings 9 

0

20

40

60

80

100

0

20

40

60

80

100

0

20

40

60

80

100

NATIONAL

SANTEE BASIN

NATIONAL 

SANTEE BASIN

EXPLANATION

ALACHLOR

ATRAZINE

DEETHYLATRAZINE

CARBARYL

CHLORPYRIFOS

CYANAZINE

DIAZINON

METOLACHLOR

PROMETON

SIMAZINE

TEBUTHIURON

DETECTION FREQUENCY, IN PERCENT

AGRICULTURAL LAND USE

URBAN LAND USE

MIXED LAND USE

INSECTICIDES HERBICIDES

INSECTICIDES HERBICIDES

INSECTICIDES HERBICIDES

STREAMS

GROUND WATER

Urban

0

5

10

15

20

25

30

35

Agricultural Mixed

 TOTAL ORGANOCHLORINE PESTICIDE CONCENTRATION

 IN SEDIMENT, IN MICROGRAMS PER KILOGRAM

LAND-USE SETTING IN STREAM BASINS

Forested

tion is the uniformly low levels of 

these pesticides detected at forested 

sites where these chemicals were 

less likely to be used.

The same pesticides detected in 

sediments were also in clam and 

fish tissues. Concentrations measured were generally much higher 

in tissue than in sediment; however, 

a direct comparison of these concentrations may not be valid 

because of potential differences in 

exposure rates of sediment and 

fish, differences in uptake by sediment organic carbon and tissue, 

and partitioning in fish tissue.

Organochlorine pesticides, such as 

DDT, can be found in streambed 

sediment and can accumulate in 

tissues of fish, such as this carp.

Figure 9. Bed sediment in forested settings has significantly lower total organochlorine pesticide concentrations 

than bed sediment in other land-use 

settings.

The most common pesticides detected in the Santee Basin included atrazine, 

simazine, tebuthiuron, prometon, and metolachlor. These pesticides were among 

the top 11 pesticides detected nationally. Consistent with national findings, 

herbicides were the most common type of pesticide detected in streams and 

aquifers in agricultural areas in the Santee Basin, whereas insecticides were 

more prevalent in urban areas. Overall, streams and aquifers that integrate 

different land uses had lower concentrations of pesticides than those that are 

dominated by either agricultural or urban land uses. Detections of pesticides in 

mixed land-use streams in the Santee Basin overall were much less frequent 

than national detections. The most striking differences between national and 

Santee Basin findings are the more frequent detections of alachlor, diazinon, and 

metolachlor in agricultural streams, simazine in agricultural and urban streams, 

and tebuthiuron in all land-use settings in the Santee Basin. The greater detection 

frequency does not appear to result from higher use of these compounds in the 

Santee Basin. 

WERE SIMILAR TO NATIONAL FINDINGS

SANTEE BASIN PESTICIDE FINDINGS
10 Water Quality in the Santee River Basin and Coastal Drainages

0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

Jacob Fork River, NC

Indian Creek, NC

South Fork Catawba River, NC

Brushy Creek, SC

Indian Creek, SC

Saluda River, SC

Congaree River, SC

Gills Creek, SC

McTier Creek, SC

Cow Castle Creek, SC

Edisto River, SC

Coosawhatchie River, SC

U.S. Environmental Protection Agency

Phosphorus Goal For Waters Not Entering

Reservoirs

U.S. Environmental Protection Agency

Phosphorus Goal For Waters Entering

Reservoirs

FLOW-WEIGHTED MEAN CONCENTRATION OF TOTAL

 PHOSPHORUS, IN MILLIGRAMS PER LITER

Phosphorus Concentrations 

in Streams Frequently 

Exceeded USEPA Goals

Nutrients measured in streams in 

the Santee Basin, such as ammonia, 

nitrite, nitrate, phosphate, and 

orthophosphate, were elevated 

above background concentrations 

in areas affected by agricultural 

and urban runoff. Of these nutrients, the only one governed by a 

drinking-water standard is nitriteplus-nitrate nitrogen (hereinafter 

referred to as nitrate) because it is 

the only nutrient that directly 

affects human health. None of the 

surface-water samples had concentrations of nitrate that were above 

the drinking-water standard of 

10 milligrams per liter (mg/L) 

(U.S. Environmental Protection 

Agency, 1996).

Phosphorus concentrations were 

above the USEPA goal in several 

rivers in the Santee Basin. For 

example, the flow-weighted mean 

annual concentration of total phosphorus in the South Fork Catawba 

River is about four times higher 

than the USEPA goal for streams 

entering a reservoir (U.S. Environmental Protection Agency, 1986) 

(fig. 10). This is important because 

many of the reservoirs in the Santee Basin are eutrophic; that is, 

they have high levels of nutrients 

that can result in excessive growth 

of algae (Stecker and Crocker, 

1991). Much of the phosphorus and 

nitrogen that feeds the algae is carried into the reservoirs by major 

rivers. The South Fork Catawba 

River flows into Lake Wylie 

directly downstream of the sampling site and is the only stream 

sampled that enters directly into a 

reservoir. 

The USEPA also has a goal of 

0.1 mg/L total phosphorus for 

streams that do not directly discharge to reservoirs (U.S. Environmental Protection Agency, 1986). 

The purpose of this goal is to prevent excessive plant growth in 

streams. Indian Creek, N.C., Congaree River, and Brushy Creek do 

not meet this goal based on mean 

annual concentrations (fig. 10). 

Only two of the streams sampled 

did not have at least one sample 

above the goal. These were Jacob 

Fork River and McTier Creek, both 

of which drain forested watersheds. 

The remaining streams had percentages of individual samples that 

exceeded the goal, ranging from 4 

to 96 percent. 

An analysis of nutrient data collected by State monitoring agencies 

during 1973–93 (Maluk and others, 

1998) showed that all but 3 of 90 

stream and lake sites exceeded the 

applicable phosphorus goal at least 

once, and 23 sites had median concentrations that exceeded the goal. 

Although 34 of the 90 sites showed 

decreasing trends in phosphorus 

concentrations, 53 showed no 

trend, and 3 had increasing trends.

Agricultural Runoff and Industrial 

Discharges are Sources of 

Nutrients in Surface Water

For all the streams in the study 

unit, except in the South Fork 

Catawba River, there is a strong 

relation between orthophosphate 

The Congaree River is one of several 

rivers in the Santee Basin that exceeded the U.S. Environmental Protection 

Agency goal for phosphorus.

Figure 10. Three streams in the Santee Basin frequently exceeded the U.S. Environmental Protection Agency goal for phosphorus in surface waters not entering reservoirs, and one exceeded the goal for waters entering reservoirs.
Major Findings 11 

PERCENTAGE OF AGRICULTURAL LAND IN STREAM BASIN

CONCENTRATION OF ORTHOPHOSPHATE,

 IN MILLIGRAMS PER LITER

SOUTH FORK

CATAWBA RIVER

0 10 20 30 40 50 60 70 80 0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0

1

2

3

4

5

6

SANTEE BASIN

NATIONAL

AGRICULTURAL

 LAND USE

URBAN LAND

USE

 MAJOR

AQUIFERS

 MEDIAN NITRATE CONCENTRATION IN

GROUND WATER, IN MILLIGRAMS PER LITER

(the predominant form of dissolved 

phosphorus in streams) 

concentrations and the percentage 

of agricultural land in the basins 

sampled (fig. 12). This relation 

most likely results from the runoff 

of phosphate-containing chemical 

fertilizer and manure from 

agricultural lands. The relation 

generally is not influenced by 

municipal waste-water discharges 

because phosphate-containing 

detergents have been banned for 

domestic use in the Santee Basin 

since the late 1990s (Litke, 1999).

The South Fork Catawba River 

has much higher concentrations of 

orthophosphate than would be predicted from the amount of agricultural land in the basin (fig. 11). 

This may result from a lack of a 

phosphorus ban on industrial users. 

The South Fork Catawba River 

Basin contains a large concentration of industries that use phosphate detergents, which are a 

potential source for the high orthophosphate levels in the South Fork 

Catawba River (Lindsey and 

Lewis, 1994).

Water-Supply Aquifers 

Rarely Exceeded DrinkingWater Standards for Nitrate

With the exceptions of nitrate, 

most nutrient concentrations in 

ground water in the Santee Basin 

were low. This is fairly typical of 

ground water in which most forms 

of nitrogen and phosphorus are 

negligible (Nolan and Stoner, 

2000). 

Nitrate concentrations exceeded 

the USEPA (1996) drinking-water 

standard of 10 mg/L in 14 of the 

150 wells sampled. Drinking water 

containing concentrations of nitrate 

above the standard can result in 

methemoglobinemia, a life-threatening illness. All but two of the 

wells that exceeded the standard 

were located in the shallow aquifer 

beneath agricultural land in the 

Coastal Plain. In fact, wells in the 

agricultural land-use study had the 

highest concentrations of nitrate 

overall, with concentrations up to 

23 mg/L and a median concentration about double the national 

NAWQA median for agricultural 

land use (fig.12). Although the 

shallow aquifer generally is not 

used for drinking-water supplies, 

the potential for movement of 

nitrate-enriched water to deeper 

aquifers used for water supply is a 

cause for concern. Wells beneath 

urban land had lower median concentrations of nitrate than wells in 

agricultural lands and were lower 

than the national NAWQA median 

for urban land use.

Nitrate concentrations measured 

in the three drinking-water supply 

aquifers sampled in the Santee 

Basin were variable. The Piedmont had the highest nitrate concentrations, followed by the 

Sandhills and Floridan aquifers 

(fig. 13). Only two wells exceeded 

the drinking-water standard for 

nitrate, one each in the Piedmont 

and Sandhills aquifers. With the 

exception of these two wells, most 

concentrations measured were well 

within the standard. One of the 

wells with a concentration above 

the standard was an irrigation well 

located in the middle of a corn and 

soybean field; the other was adjacent to a golf course. These results 

suggest that most wells in these 

three aquifers are safe from high 

levels of nitrate, but some concern 

is justified for wells located near 

areas with high fertilizer use.

The higher nitrate concentrations 

in the Piedmont and Sandhills aquifers are related to the lack of conFigure 11. The concentration of orthophosphate in streams is directly related 

to the percentage of agricultural land in 

the stream basin except for the South 

Fork Catawba River.

Figure 12. Nitrate concentrations in shallow ground water in 

agricultural areas were higher than those in urban areas and in 

major aquifers.
12 Water Quality in the Santee River Basin and Coastal Drainages

100

140

130

120

110

150

Cow Castle

Creek

Unsaturated zone

Water table

Sand and clay

surficial aquifer

100

140

130

120

110

150

ALTITUDE, IN FEET

Datum is sea level

Vertical scale is greatly exaggerated

0 1,000 FEET 200 400 600 800

Hay field

Corn field

Pines

Santee Limestone

0.4

4.5

4.7

3.6

2.4

2.2

1.8

28.3

12.1

3.7

3.2

2.3

11.9

0.8

12.7

5.7

5.1

0.6

3.1

2.0

2.0

8.1

14.1

9.6

NITRATE CONCENTRATION LESS

THAN 10 MILLIGRAMS PER LITER

EXPLANATION

WELL; NUMBERS INDICATE

NITRATE CONCENTRATIONS,

IN MILLIGRAMS PER LITER

12.4

0.7

3.8

NITRATE CONCENTRATION GREATER

THAN 10 MILLIGRAMS PER LITER

DIRECTION OF GROUNDWATER FLOW

0 100 200 300 METERS

finement for these aquifers, which 

readily allows the downward 

movement of surficial contaminants. Water in these aquifers often 

has high dissolved oxygen concentrations, which prevents denitrification (the removal of nitrate by 

conversion to nitrogen gas). By 

comparison, the Floridan aquifer 

has the lowest nitrate concentrations because it is confined, meaning little water moves vertically 

into the aquifer, and it has little dissolved oxygen, a condition which 

can promote denitrification. 

Nitrate in Ground Water Can Affect 

Nitrate Concentrations in Streams

Local conditions can strongly 

affect the nitrogen concentrations 

in ground water and how much 

nitrate discharges from ground 

water to surface water. A study of 

the transport of nitrate in ground 

water was conducted at an agricultural site adjacent to Cow Castle 

Creek, S.C. (fig. 14). At this site, 

ground water beneath a corn field 

had concentrations of nitrate more 

than 28 mg/L, nearly three times 

the drinking-water standard. Along 

the ground-water flow path, nitrate 

concentrations decreased to less 

than 5 mg/L. 

Directly below the streambed, 

nitrate concentrations were above 

4 mg/L. However, as ground water 

moves upward to the stream, it 

passes through an organic-rich 

zone containing little dissolved 

oxygen. Denitrification occurring 

in this zone results in water with a 

nitrate concentration of only 

0.4 mg/L. 

Denitrification may not always 

be effective in removing nitrate at 

all locations where ground water 

discharges to Cow Castle Creek. 

This is evidenced by the high concentrations of nitrate measured in 

Cow Castle Creek during low flow 

when most streamflow is attributed 

to ground-water discharge.

Figure 14. Concentrations of nitrate are reduced through denitrification as ground water flows to Cow Castle Creek. Typical wells

used for water supply in this area are greater than 100 feet deep. Nitrate concentrations at that depth generally are not above

drinking-water standards.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

FLORIDAN

 AQUIFER

PIEDMONT

 AQUIFER

SANDHILLS

 AQUIFER

NATIONAL

 MEDIAN

 MEDIAN CONCENTRATION OFNITRATE, IN MILLIGRAMS PER LITER

Figure 13. The Piedmont and Sandhills

aquifers had higher median nitrate concentrations than the Floridan aquifer.

Water levels were measured simultaneously in Cow Castle Creek and at 

multiple depths in the aquifer below 

the creek. Under most streamflow 

conditions, water from the aquifer was 

moving upward into the creek.
Major Findings 13 

AVERAGE ANNUAL CONCENTRATION

OF TOTAL PHOSPHORUS--IN

MILLIGRAMS PER LITER

Mixed Land-Use Areas

Urban Areas

Agricultural Areas

BACKGROUND CONCENTRATIONS

AVERAGE ANNUAL TOTAL PHOSPHORUS INPUT--

IN POUNDS PER ACRE, BY COUNTY, FOR 1995-98. 

INPUTS ARE FROM FERTILIZER AND MANURE

EXPLANATION

SANTEE BASIN

SANTEE BASIN

SANTEE BASIN

prevention of nuisance plant growth in flowing waters

USEPA desired goal of 0.1 milligrams per liter for 

Bold outline indicates median values greater than

not discharging directly to lakes and impoundments

Highest (greater than 0.27)

Medium (0.05 to 0.27)

Lowest (less than 0.05)

Greater than 5 pounds per acre

2 to 5 pounds per acre

Less than 2 pounds per acre

Six of the 12 streams sampled in the Santee Basin 

had average concentrations of total phosphorus that 

were within the medium concentration range of all 

streams sampled in the NAWQA Program. The 

exceptions were an agricultural area drained by 

Indian Creek in North Carolina, which ranked high 

nationally, and two mixed land-use streams, which 

were in the lowest category for phosphorus. 

Nationally, higher concentrations of phosphorus 

corresponded to areas of the Midwest that also had 

high inputs of phosphorus from fertilizer and manure 

that were applied to agricultural lands. Phosphorus 

inputs from agriculture in the Santee Basin were 

typically in the low to middle range. The two mixed 

land-use sites that had the lowest phosphorus 

concentrations compared to national results were 

located on the Saluda and Edisto Rivers. The 

Saluda River site is located downstream from a 

major reservoir that traps much of the phosphorus 

carried into the system. The Edisto River is located 

in the Coastal Plain and mostly drains forested and 

agricultural lands. Extensive wetlands border the 

Edisto River and may act as local traps for 

phosphorus attached to sediment.

PHOSPHORUS CONCENTRATIONS IN THE SANTEE BASIN 

WERE IN THE MIDDLE RANGE OF NATIONAL RESULTS
14 Water Quality in the Santee River Basin and Coastal Drainages

Bed Sediment Had Low 

Concentrations of Trace 

Elements

Trace elements in bed sediment 

were detected frequently but 

mostly at concentrations below 

those expected to affect aquatic life 

(Canadian Council of Ministers of 

the Environment, 1995). Arsenic 

and lead exceeded aquatic standards in one sample each, and 

chromium exceeded standards in 

four samples. The samples with 

elevated chromium concentrations 

were not associated with any particular land use; however, most of 

these samples were collected at 

sites in the Piedmont. This suggests 

that the elevated concentrations 

may be naturally occurring as a 

result of geologic conditions in the 

Piedmont. 

Regional differences in bed sediment trace-metal concentrations 

were observed in the study area. In 

general, a decrease in the bed-sediment concentrations of arsenic, 

chromium, copper, nickel, and zinc 

occurs from the Blue Ridge southeastward across the Piedmont to 

the Coastal Plain. In the same 

direction, an increase in the bedsediment concentrations of lead, 

mercury, and selenium occurs. 

These differences are likely a result 

of geologic differences among the 

areas (Abrahamsen, 1999).

A comparison of land use with 

bed sediment trace-element concentrations indicates that lead is 

significantly higher in sediment 

from urban streams than in sediment from forested streams. 

Neither agricultural nor mixed 

land-use streams had significantly 

higher concentrations of lead than 

forested streams (Abrahamsen, 

1999).

0 0.02 0.04 0.06 0.08 0.10 0.12

AVERAGE METHYLMERCURY TO TOTAL 

MERCURY RATIO FOR WATER AND SEDIMENT

GREAT SALT LAKE BASINS

LOWER TENNESSEE RIVER BASIN

OAHU ISLAND

SACRAMENTO BASIN

TRINITY RIVER BASIN

ALLEGHENY AND MONONGAHELA BASINS

MOBILE RIVER AND TRIBUTARIES

NORTHERN ROCKIES INTERMONTANE BASINS

NEVADA BASIN AND RANGE

COOK INLET BASIN

DELAWARE RIVER BASIN

GREAT AND LITTLE MIAMI RIVER BASINS

UPPER COLORADO BASIN

YELLOWSTONE RIVER BASIN

ACADIA-PONTCHARTRAIN

SANTA ANA RIVER

LONG ISLAND AND NEW JERSEY COASTAL DRAINAGES

UPPER ILLINOIS RIVER BASIN

NEW ENGLAND COASTAL BASINS

SOUTH FLORIDA

SANTEE BASIN

NAWQA STUDY AREAS SAMPLED FOR THE NATIONAL PILOT

STUDY OF MERCURY CONTAMINATION

Mercury is a widespread and extremely toxic contaminant that affects the Nation’s 

aquatic ecosystems. Approximately 80 percent of the fish consumption advisories 

in the Nation were issued as a result of contamination by mercury (U.S. Environmental Protection Agency, 1998). Methylmercury is the form of mercury that is 

easily accumulated in the tissues of organisms. As part of the NAWQA Program, a 

nationwide investigation of methylmercury in water, sediment, and fish tissues was 

conducted (Krabbenhoft and others, 1999). Analysis of samples collected in the 

Santee Basin indicated that they had the greatest methylation efficiency (the ratio 

of methylmercury to total mercury) in the Nation. In other words, conditions at the 

sites sampled in the Santee Basin are such that a relatively small amount of elemental mercury in water can result in high concentrations of methylmercury being 

available for accumulation in fish tissue. The types of sites sampled were primarily 

blackwater streams, which typically have large amounts of dissolved organic carbon and low dissolved oxygen concentrations. The bacteria that convert elemental 

mercury to methylmercury thrive under these conditions. Many of the streams that 

are covered by State fish-consumption advisories are blackwater streams. 

MERCURY CONTAMINATION POTENTIAL IN

SANTEE BASIN WAS HIGHEST IN NATION
Major Findings 15 

because of high levels of mercury 

in 49 rivers and reservoirs in the 

Santee Basin, including the Edisto 

River. 

Selenium

Zinc

CLAM TISSUE

FISH LIVER

BED SEDIMENT

MEDIAN CONCENTRATION OF TRACE ELEMENTS IN BED SEDIMENT AND TISSUE, IN

 MICROGRAMS PER KILOGRAM

0

50

100

150

200

0

2

4

6

8

10

Copper

Cadmium

0

100

200

300

400

500

600

0

1

2

3

4

5

0

1

2

3

4

5

6

0

10

20

30

40

50

60

70

80

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

CLAM TISSUE

FISH LIVER

BED SEDIMENT

Arsenic

Chromium

Lead

Nickel

Figure 15. Cadmium, copper, selenium, and zinc were detected at higher concentrations 

in clam and fish tissue than in sediment, suggesting that they accumulate in the tissues. 

Conversely, arsenic, chromium, lead, and nickel were detected in lower concentrations in 

tissues than in sediment, indicating that these metals do not accumulate in the tissues.

Trace Elements Accumulated 

in Clam Tissue and Fish 

Livers

 Trace metals are naturally 

occurring and were detected in all 

fish liver and clam tissue samples 

collected. Nine trace elements 

(arsenic, cadmium, chromium, 

copper, lead, mercury, nickel, selenium, and zinc) have been classified as priority pollutants because 

they are toxic to aquatic organisms 

in low concentrations (Code of 

Federal Regulations, 1996). Of 

these nine metals, concentrations 

of cadmium, copper, selenium, and 

zinc were higher in clams and fish 

liver tissue than those measured in 

sediment. Carp liver tissue contained significantly higher concentrations of these metals than those 

in clams and bed sediment, indicating that the metals accumulate in 

fish livers. Concentrations of 

arsenic, chromium, lead, and 

nickel were significantly lower in 

tissues than in sediment, suggesting that these metals do not accumulate in tissues (fig. 15). 

Concentrations of mercury were 

higher in clam tissue than in sediment and fish livers. Although data 

suggest that some metals accumulate in tissues, most metals do not 

have criteria for assessing risk to 

human health or aquatic wildlife 

associated with fish consumption.

Concentrations of mercury in 

clams and fish liver tissue from the 

Edisto River were 24 and 8 times 

greater, respectively, than the 

South Carolina action level for 

issuance of a fish-consumption 

advisory. Data collected in the 

NAWQA Program cannot be used 

to assess potential risk to human 

health because fish livers were 

used for analyses, whereas fish fillets are needed to assess humanhealth risk. Consumption advisories generally are not applied to 

clams because few humans consume them. The South Carolina 

Department of Health and Environmental Control (2000) has issued 

fish-consumption advisories 
16 Water Quality in the Santee River Basin and Coastal Drainages

EXPLANATION

AQUIFERS

North Carolina

South Carolina

Blue Ridge

Piedmont

Sandhills

Floridan

Less than 300 picocuries

per liter

Greater than 300 but less

than 4,000 picocuries per liter

Greater than 4,000

picocuries per liter

RADON CONCENTRATION

RADON--222 IN GROUND WATER

1,000 picocuries per liter (pCi/L)

Study Units with radon concentrations

exceeding:

EXPLANATION

No data

300 pCi/L in less than 25 percent of samples

300 pCi/L in at least 25 percent of samples

600 pCi/L in at least 25 percent of samples

Santee

Basin

Radon Exceeded Proposed 

Standards in Many Wells

Ninety-six percent of the 90 

wells sampled in drinking-water 

supply aquifers of the Santee Basin 

contained measurable quantities of 

radon, a colorless, odorless gas that 

can cause cancer in humans. The 

gas results from the radioactive 

decay of uranium in rocks and soil 

and can enter homes directly from 

the soil or in drinking water supplied by wells. Radon is a health 

risk through direct inhalation of the 

gas and from drinking water contaminated with radon. 

Of the 90 wells sampled, radon 

exceeded the USEPA’s (1999) proposed maximum contaminant level 

(MCL) of 300 picocuries per liter 

(pCi/L) in 100, 47, and 17 percent 

of the wells in the Piedmont, 

Sandhills, and Floridan aquifers, 

respectively (fig. 16). For wells not 

meeting the MCL, the USEPA has 

proposed an Alternative Maximum 

Contaminant Level (AMCL) of 

4,000 pCi/L. To comply with the 

AMCL, the State or local water 

utility must develop indoor air 

radon-reduction programs and 

reduce radon levels in drinking 

water to 4,000 pCi/L. Of the wells 

that were sampled in the Piedmont, 

Sandhills, and Floridan aquifers, 20 

percent, zero percent, and less than 

1 percent, respectively, exceeded 

the proposed AMCL.

Wells in the Piedmont had much 

higher concentrations of radon, on 

average, than wells sampled in the 

Sandhills and Floridan aquifers 

(fig. 16). This results from the 

greater relative abundance of minerals containing uranium in the 

metamorphic rocks that compose 

the Piedmont aquifer. The same 

bedrock underlies the Sandhills and 

Floridan aquifers, but generally at 

depths ranging from several hundred to several thousand feet.

Figure 16. Radon concentrations were highest in the Piedmont and 

Sandhills aquifers, resulting from naturally high levels of uranium in 

near-surface rocks and sediment.

Radon concentrations in the Santee Basin were among the highest measured in 

the Nation. These high concentrations result from radioactive decay of naturally 

occurring minerals in the soil and rock that underlie the study area and compose 

the aquifer in the Piedmont part of the study area. The Piedmont metamorphic 

rocks are present in many eastern coastal States and probably account for the 

high radon concentrations observed in Study Units located in those States.

RADON CONCENTRATIONS WERE HIGH

IN THE SANTEE BASIN
Major Findings 17 

Volatile Organic Compounds 

Were Common in Urban 

Ground Water

All but 3 of 30 monitoring wells 

installed in commercial and residential areas of Columbia, S.C., 

contained a variety of volatile 

organic compounds (VOCs), a 

group of chemicals that includes 

gasoline additives, solvents, and 

disinfection by-products (Reuber, 

1999). Thirty-five such compounds were detected. Most wells 

contained three or more VOCs, and 

one well contained 15 different 

VOCs. 

Most of the VOC detections 

were at extremely low levels. The 

five VOCs detected with the highest concentrations were methyl 

tert-butyl ether (MTBE), trichloroethene (TCE), acetone, tert-amyl 

methyl ether (TAME), and trichloromethane. Of the 35 detected 

VOCs, 14 have established drinking-water standards; of these, only 

TCE exceeded the standard. Currently there is no standard for 

MTBE, but the MTBE concentration in one well exceeded a drinking-water advisory.

Some of the most frequently 

detected compounds included 

trichloromethane, chloromethane, 

and bromodichloromethane. These 

compounds can result from the 

chlorination of drinking water and 

can enter ground water by infiltration from irrigation systems or 

from leaky water-supply lines. 

Other VOCs that were detected 

were solvents, such as TCE, tetrachloroethene, and acetone. These 

compounds have commercial and 

industrial uses as degreasers and 

dry-cleaning solvents, but they are 

often used in households for similar purposes. The gasoline additives MTBE and TAME and the 

gasoline component benzene also 

were detected in Columbia’s 

ground water. These compounds 

can enter ground water from leaking gasoline storage tanks, spills, 

and potentially through atmospheric deposition (Lopes, 1998). 

The diffuse, nonpoint nature of 

sources of VOCs in ground water 

makes it difficult to attribute 

detected compounds to particular 

homes or businesses, posing a 

problem for scientists who seek to 

establish the relative importance of 

these sources and for regulators 

who seek to educate the public or 

control the release of toxic substances. 

Volatile Organic Compounds in 

Streams Can Result from GroundWater Discharge and Urban Runoff

Ten VOCs were detected in 

seven monthly stream-water samples that were collected from Gills 

Creek, an urban stream in the 

Columbia metropolitan area. 

MTBE, chloromethane, methylbenzene, chlorobenzene, and acetone were detected most frequently. 

None of the VOCs detected in Gills 

Creek were at concentrations 

exceeding drinking-water or 

aquatic-life standards. Six of the 

VOCs detected do not have standards.

VOCs have many sources, 

including contaminated precipitation, surface-water runoff, and 

ground-water discharge. Though 

the sources are diffuse and hard to 

measure directly, inferences can be 

made about the likely sources. For 

example, samples collected in Gills 

Creek while the water level was rising during a rainstorm indicate that 

as streamflow increased, the concentration of acetone increased. 

This suggests that the source of 

acetone in the samples was from 

contaminated precipitation or 

stormwater runoff (Lopes and 

others, 2000). If the acetone 

resulted from continuously discharging ground water, the concentration would be expected to 

decrease as dilution by rainfall and 

runoff increased. Shallow ground water in the Columbia, S.C., metropolitan area contains a

variety of volatile organic compounds, but mostly at low concentrations.
18 Water Quality in the Santee River Basin and Coastal Drainages

 During the summer of 1996, 20 

different VOCs were detected at 

low concentrations in individual 

samples collected at 16 surfacewater sites scattered throughout the 

Gills Creek Basin. The compounds 

detected in the highest concentrations included MTBE, 1,1-dichloroethene, trichloroethene, 

methylbenzene, and 1,2-dibromo3-chloropropane—all solvents 

except for MTBE, which is a gasoline additive. Fifteen of the compounds detected in surface water 

also were present in the Columbia 

ground-water samples. This result 

is not surprising because the samples were collected during low 

streamflow conditions when the 

ground-water contribution to Gills 

Creek is greatest; consequently, 

VOCs from contaminated ground 

water most likely would be 

detected in stream samples.

Drinking-Water Aquifers Had 

Low Concentrations of 

Volatile Organic Compounds

Of the 90 wells sampled in the 

Piedmont, Sandhills, and Floridan 

aquifers, 62 contained detectable 

concentrations of VOCs. All of the 

28 compounds detected met 

USEPA drinking-water standards; 

however, 19 of the compounds did 

not have standards. The VOCs 

measured had widely ranging 

detection limits, making comparisons among compounds and aquifers difficult. A subset of the 

compounds having detection limits 

of 0.05 microgram per liter (μg/L) 

or lower was used to make comparisons. This comparison shows that 

about twice as many wells in the 

Sandhills aquifers contain VOCs as 

those in the Floridan and Piedmont 

aquifers. The more frequent occurrence of VOCs in the Sandhills 

aquifers probably relates to their 

greater susceptibility to contamination.

Data on VOCs in drinking-water 

aquifers indicate that although 

these compounds are widespread, 

concentrations are sufficiently low 

that human health is not immediately at risk. However, the fact that 

detections were so frequent suggests that aquifers are susceptible 

to contamination and should be 

carefully monitored.

Stormwater samples for volatile organic compounds were collected by using

special samplers developed for the

NAWQA Program. Ground water affects the quality of surface water 

Presently, surface water is used for most public water supplies in the 

Columbia metropolitan area. However, the quality of these supplies is largely 

controlled by ground-water quality, especially during summer months. In 

areas of the basin with sandy soils, such as the Sandhills, flow in streams is 

contributed mostly by discharge from ground water. Discharging ground 

water transports contaminants, including VOCs, that can result in waterquality problems in streams and lakes. Consequently, the health of aquatic 

organisms and surface-water drinking supplies can be affected by the 

chemical quality of shallow ground water discharged to streams and 

reservoirs. Several streams in the metropolitan area, including Penn Branch 

and Jackson Creek, have high concentrations of nutrients and pesticides that 

evidence suggests result from ground-water discharge (Maluk, 1999). 
Major Findings 19 

0

10

20

30

40

50

Forested Urban Agricultural Mixed

PERCENTAGE OF SAMPLES EXCEEDING SOUTH

 CAROLINA BACTERIA STANDARDS

LAND USE IN BASIN

Urban and Agricultural 

Streams Had High 

Concentrations of Bacteria 

Thirteen of 17 streams sampled 

for fecal coliform bacteria had at 

least one sample that exceeded the 

South Carolina single-sample 

standard of 400 colonies per 100 

milliliters (cols/100 mL; South 

Carolina Department of Health and 

Environmental Control, 1992). 

This standard was implemented to 

reduce the risk of gastrointestinal 

disorders that are associated with 

recreational contact with water 

containing elevated levels of 

bacteria. All concentrations 

measured in this report were 

compared to South Carolina 

standards for consistency; North 

Carolina does not recognize a 

single-sample standard.

Urban and agricultural streams 

had more concentrations of bacteria that exceeded standards than 

forested and mixed land-use 

streams (fig. 17). Several creeks 

repeatedly had high concentrations 

of bacteria. For example, one of the 

urban streams sampled, Brushy 

Creek, exceeded the standard in 60 

percent of the samples collected. 

The highest bacterial concentrations measured were at agricultural 

sites, such as Cow Castle Creek 

and Indian Creek, N.C., which had 

concentrations of 21,600 and 

12,000 col/100 mL, respectively. 

The highest concentrations 

observed in urban streams were 

much lower—around 2,000 col/100 

mL. Forested streams generally had 

the lowest peak concentrations, 

ranging from about 500 to 1,000 

col/100 mL. Samples were collected under all flow conditions, 

and higher concentrations as well 

as standard exceedances tended to 

occur at higher streamflows.

Stream Size is Important

All of the regularly monitored 

small streams exceeded the South 

Carolina single-sample standard 

for bacteria. Most large rivers did 

not exceed the standard during the 

period sampled, including the 

Wateree, Saluda, Congaree, and 

Edisto Rivers. The median bacterial concentrations in streams with 

drainage areas larger than 100 

square miles (mi2

) were significantly lower than those in streams 

with drainage areas less than 100 

mi2. Because major rivers and 

small streams have similar sources 

of bacteria, the most likely reason 

for the differences in bacterial levels is dilution by the larger flows in 

the major rivers.

Sources of Bacteria

A comparison of bacterial concentrations to the physical and 

chemical parameters of the water 

indicate that surface-water runoff 

accounts for much of the elevated 

fecal coliform concentrations 

(Wilhelm and Maluk, 1998). Bacterial concentrations increased as 

streamflow, organic nitrogen, 

organic carbon, phosphorus, and 

suspended-sediment concentrations 

increased. Because increases in 

these parameters usually result 

from surface-water runoff, the 

implication is that the increase in 

bacteria also resulted from runoff.

In agricultural areas, bacteria in 

runoff may result from applications 

of manure to fields and from animal holding and feeding areas. 

Urban sources include runoff from 

lawns containing pet wastes, leaking or failed septic tanks and sewer 

lines, and municipal or industrial 

discharges. Bacterial contamination in forested areas most likely 

results from fecal contamination by 

wildlife.

Figure 17. Urban and agricultural streams had more concentrations

of bacteria that exceeded South Carolina State standards than

forested and mixed land-use streams.

Bacterial cultures were prepared and 

counted in a mobile field laboratory 

and in the USGS South Carolina District laboratory.
20 Water Quality in the Santee River Basin and Coastal Drainages

0

0.01

0.02

0.03

0.04

0.05

0

5

10

15

20

25

30

35

Forested Agricultural Urban Mixed

Forested Agricultural Urban Mixed

ATRAZINE

AMMONIA

EPT TAXA

CONTAMINANT-INTOLERANT 

FISH SPECIES

MEDIAN CONCENTRATION OF AMMONIA AND ATRAZINE, IN MICROGRAMS PER LITER

NUMBER OF EPHEMEROPTERA, PLECOPTERA, AND TRICHOPTERA TAXA AND PERCENTAGEOF CONTAMINANT-INTOLERANT FISH SPECIES

Biological Communities 

Reflected Land-Use 

Differences

Biological communities that 

inhabit streams in Santee Basin 

agricultural and urban areas were 

indicative of degraded water quality compared to those that inhabit 

streams that drain forested areas. 

Fish that have a low tolerance for 

contamination make up a smaller 

percentage of the fish community 

at agricultural and urban sites than 

at forested sites (fig. 18). This can 

result because fish such as darters 

and shiners that are sensitive to 

contaminants do not thrive at 

degraded sites. Other species such 

as catfish, redbreast sunfish, and 

some minnows that are relatively 

unaffected by contaminants will 

take the place of the more sensitive 

fish.

Urban and agricultural streams 

also had lower numbers of invertebrate species that are intolerant of 

contaminants than forested and 

mixed land-use streams. This is 

evidenced by the lower numbers of 

Ephemeroptera, Plecoptera, and 

Trichoptera (EPT) taxa, a group of 

aquatic insects that are relatively 

intolerant of contamination, at 

urban and agricultural sites. The 

USEPA (Plafkin and others, 1989) 

uses the presence or absence of 

EPT taxa as an indicator of aquatic 

community health. 

Water-quality constituents and 

contaminant-intolerant species are 

related (fig.18). Median concentrations of ammonia, a nutrient associated with wastewater discharges, 

and atrazine, an agricultural and 

turfgrass herbicide, are highest at 

urban and agricultural sites, corresponding to low numbers of contaminant-intolerant fish and 

invertebrate species. This suggests 

that these water-quality constituents have an effect on the aquatic 

community; however, other factors, 

primarily those associated with 

aquatic habitats, can affect aquatic 

community health in ways that are 

similar to those that result from 

changes in water quality. In addition, sample sites were located in 

several different physiographic 

provinces, including the Blue 

Ridge, Piedmont, and Coastal 

Plain. Differences in species distributions and habitat in these different settings can make comparisons 

difficult to interpret. Most likely, a 

combination of water quality and 

habitat disturbance associated with 

agricultural and urban land uses 

results in the observed differences 

in biological communities. 

Over 85 fish species were identified

during ecological sampling in the

Santee Basin.

Figure 18. Compared to forested sites, urban and agricultural sites

have higher concentrations of atrazine and ammonia as well as lower

numbers of fish and invertebrates that are intolerant of contamination.
Major Findings 21 

Santee

 Basin

*Higher values suggest a more degraded stream site

Santee

 Basin

*Higher values suggest a more degraded stream site

Invertebrate Status Index

A multimetric index was developed to 

compare invertebrate populations 

nationally. The index is an average of 

11 metrics that summarize changes in 

richness, tolerance, trophic condition, 

and dominance associated with waterquality degradation. Only one site in the 

Santee Basin, an urban stream, was 

placed in the highest 25-percent 

category. The remaining Santee Basin 

sites were in the middle category, 

except for Jacob Fork River and McTier 

Creek, which were in the lowest 

category. Both of these sites represent 

the least degraded water quality in the 

study area and were located in areas 

with the least effects of human activity. 

Nationally, urban and agricultural sites 

tended to have the most degraded 

invertebrate communities according to 

this index.

Algal Siltation Index

Algal data collected in each of the 

NAWQA Study Units were combined 

and compared to show differences in 

the percentage of species that are able 

to avoid burial by sediment (Bahls and 

others, 1992). High percentages of 

these mobile algae are indicative of 

siltation of benthic habitats. Two sites in 

the Santee Basin were in the highest 

25-percent category. One of these sites 

is the Edisto River, a blackwater river 

that has low light penetration.The high 

ranking at this site may result from lowlight conditions that favor mobile algal 

species. Other variables that can lower 

light levels in streams can affect this 

index, including turbidity and forest 

canopy closure.

SANTEE BASIN STREAMS WERE IN THE MIDDLE OF NATIONAL

BIOLOGICAL RANKINGS
22 Water Quality in the Santee River Basin and Coastal Drainages

STUDY UNIT DESIGN

EXPLANATION

0 50 KILOMETERS

0 50 MILES

FIXED SITE

INTENSIVE FIXED

SITE

BED SEDIMENT AND

TISSUE SITES

0 50 KILOMETERS

0 50 MILES

EXPLANATION

SUBUNIT SURVEY

WELLS

URBAN LAND-USE

WELLS

AGRICULTURAL LANDUSE WELLS

FLOW-PATH STUDY

SITE

Blue Ridge

Piedmont

AQUIFERS

Sandhills

Floridan

EXPLANATION

0 50 KILOMETERS

0 50 MILES

FORESTED WETLAND

INITIATIVE

CONGAREE SWAMP

NATIONAL MONUMENT

EDISTO RIVER

MERCURY STUDY

STREAM CHEMISTRY AND BIOLOGY

Fixed sites were sampled to examine differences in streamwater 

quality due to the environmental setting, a combination of land use, 

geology, physiography, and climate. Intensive fixed sites were a 

subset of fixed sites that were sampled more frequently to determine the occurrence and seasonal variability of pesticides. Aquatic 

community structure, including algae, fish, and macroinvertebrates, 

was studied at each fixed site to quantify the effects of water quality 

on stream biota. Synoptic studies focused on low streamflow conditions in an urban setting in Gills Creek, S.C., and a mixed land-use 

setting in the South Fork Catawba River Basin, N.C. Streambed 

sediments and fish and clam tissues were sampled to determine the 

occurrence and distribution of trace elements and organic compounds. 

SPECIAL STUDIES

The effects of a forested wetland on nutrient concentrations in 

stream water were studied as part of the Forested Wetland Initiative, 

a joint research project with the U.S. Forest Service. Baseline data 

on water quality and aquatic communities were collected in cooperation with the National Park Service at Congaree Swamp National 

Monument (Maluk and Abrahamsen, 1999). A study to determine 

the accumulation of mercury in fish tissues was conducted in the 

Edisto River Basin. 

GROUND-WATER CHEMISTRY

Subunit surveys were conducted in three drinking-water 

supply aquifers to assess overall water quality. Land-use 

studies in urban and agricultural settings evaluated the 

effects of these land uses on shallow ground water. An 

agricultural flow-path study examined the transport and 

fate of nutrients and pesticides in shallow ground water.
Study Unit Design 23 

SUMMARY OF DATA COLLECTION IN THE SANTEE RIVER BASIN AND COASTAL DRAINAGES, 1995–98

Study

component What data were collected and why Types of sites sampled Number of 

sites

Sampling frequency 

and period

Stream Chemistry and Biology

Fixed sites Streamflow was measured continuously and samples were 

collected monthly for major ions, nutrients, organic carbon, suspended sediment, bacteria, pesticides, and physical properties to describe concentration, seasonal 

variability, and loads.

Streams draining basins ranging in size 

from 14 to 7,850 square miles and representing forested, agricultural, urban, and 

mixed land uses.

13

Monthly, plus 3–6 storms 

(October 1995–September 1997)

Pesticides (February, May, 

August 1996)

Intensive fixed 

sites

In addition to the above constituents, samples were analyzed for dissolved pesticides to describe concentration 

and seasonal variability. 

A subset of fixed sites draining agricultural, urban, and mixed land uses. 3Weekly during growing 

season (February 1996–

October 1997)

Urban synoptic 

study 

Streamflow, major ions, nutrients, organic carbon, suspended sediment, bacteria, pesticides, volatile organic 

compounds, and physical properties were determined 

under low-flow conditions to describe concentrations and 

spatial distributions.

Urban streams draining basins ranging in 

size from 0.5 to 59.4 square miles. 16 September 1996

South Fork 

Catawba River 

synoptic study 

Streamflow, major ions, nutrients, organic carbon, suspended sediment, bacteria, and physical properties were 

determined under low-flow conditions to describe concentrations and spatial distributions. 

Mixed land use streams draining basins 

ranging in size from 5 to 350 square 

miles.

20 October 1997

Streambed sedimentsStreambed sediments were analyzed for trace elements and 

hydrophobic pesticides and other organic compounds to 

determine occurrence and spatial distribution.

Sediment depositional zones at all fixed 

sites and other selected sites. 20

Summer 1995

Aquatic biota Clams and fish livers were analyzed for trace metals, and 

clams and whole fish were analyzed for organic compounds to determine occurrence and spatial distribution.

All fixed sites and other selected sites.

20

Summers 1995, 1996

Fixed site reach 

assessment

Fish, benthic invertebrates, algae, and aquatic and riparian 

habitats were sampled and described to assess aquatic 

biological community structure in different land uses and 

associated habitats.

Stream reaches located at or near fixed 

sites. Sites represent the variety of land 

uses, geology, and physiography within 

the Santee Basin

13

Once in 1996 or 1997; 

Multiyear sites, once during 1996–98

Ground-Water Chemistry

Study unit surveyMajor ions, nutrients, pesticides, volatile organic compounds, dissolved organic carbon, trace metals, radon 

and physical parameters analyzed in three major drinking-water aquifers to determine ground-water quality. 

Randomly chosen existing pubic supply, 

private domestic, irrigation, and industrial supply wells in the Piedmont, 

Sandhills, and Floridan aquifers.

90 (30 per 

aquifer)

Sandhills—Summer 1996

Floridan—Spring 1999

Piedmont—Fall 2000

Urban land-use 

study

Major ions, nutrients, pesticides, volatile organic compounds, dissolved organic carbon, and physical parameters analyzed in shallow ground water in the Columbia, 

South Carolina, metropolitan area.

Wells installed at randomly chosen commercial/residential land-use areas. 30Summer 1996

Agricultural 

land-use study

Major ions, nutrients, pesticides, dissolved organic carbon, 

and physical parameters analyzed in shallow ground 

water in row-crop agricultural lands of the lower Coastal 

Plain

Wells installed at randomly chosen rowcrop land-use areas. 30Summer 1997

Flow-path 

study

Major ions, nutrients, pesticides, dissolved organic carbon, 

and physical parameters analyzed to determine fate and 

transport of pesticides and nutrients in an agricultural setting.

Multidepth wells installed along a groundwater flow path in the lower Coastal 

Plain.

34

November 1997, April and 

August 1997

Special Studies

Forested Wetland InitiativeMajor ions, nutrients, and organic carbon analyzed 

upstream and downstream from a forested wetland to 

compare changes in concentrations.

Coosawhatchie River in the lower Coastal 

Plain. 2

Approximately quarterly, 

1996–97 

Congaree 

Swamp 

National Monument

Streamflow, major ions, nutrients, organic carbon, suspended sediment, bacteria, pesticides, and physical properties to describe concentrations and seasonal variability. 

Fish, benthic invertebrates, algae, and aquatic habitat 

described to assess aquatic biological community structure.

Streams draining basins ranging in size 

from 32 to 70 square miles with agricultural, urban, and forested land uses that 

drain into Congaree Swamp. 

4 Quarterly 1996–98

Edisto mercury 

study

Sediment, stream water, aquatic insects, and vegetation, and 

whole fish analyzed for elemental and methyl mercury to 

examine bioaccumulation of mercury.

Blackwater streams in the Edisto River 

Basin and a reference site in the Piedmont

5 Once in 1998
24 Water Quality in the Santee River Basin and Coastal Drainages

GLOSSARY 

Ammonia—A compound of nitrogen and hydrogen (NH3) that is a common by-product of animal waste. Ammonia readily converts to nitrate 

in soils and streams. 

Aquatic-life criteria—Water-quality guidelines for protection of aquatic 

life. Often refers to U.S. Environmental Protection Agency waterquality criteria for protection of aquatic organisms. 

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

usable quantities of water to a well. 

Atmospheric deposition—The transfer of substances from the air to the 

surface of the Earth, either in wet form (rain, fog, snow, dew, frost, 

hail) or in dry form (gases, aerosols, particles). 

Bedrock—General term for consolidated (solid) rock that underlies soils or 

other unconsolidated material. 

Bed sediment—The material that temporarily is stationary in the bottom of 

a stream or other watercourse. 

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). 

Confined aquifer (artesian aquifer)—An aquifer that is completely filled 

with water under pressure and that is overlain by material that 

restricts the movement of water. 

Confining layer—A layer of sediment or lithologic unit of low permeability that bounds an aquifer, 

Contamination—Degradation of water quality compared to original or natural conditions due to human activity. 

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. 

Detect—To determine the presence of a compound. 

DDT—Dichloro-diphenyl-trichloroethane. An organochlorine insecticide 

no longer registered for use in the United States. 

Drainage area—The drainage area of a stream at a specified location is that 

area, measured in a horizontal plane, which is enclosed by a drainage 

divide. 

Drinking-water standard or guideline—A threshold concentration in a 

public drinking-water supply, designed to protect human health. As 

defined here, standards are U.S. Environmental Protection Agency 

regulations that specify the maximum contamination levels for public 

water systems required to protect the public welfare; guidelines have 

no regulatory status and are issued in an advisory capacity. 

Eutrophication—The process by which water becomes enriched with plant 

nutrients, most commonly phosphorus and nitrogen. 

Fecal bacteria—Microscopic single-celled organisms (primarily fecal 

coliforms and fecal streptococci) found in the wastes of warmblooded animals. Their presence in water is used to assess the sanitary 

quality of water for body-contact recreation or for consumption. Their 

presence indicates contamination by the wastes of warm-blooded animals and the possible presence of pathogenic (disease producing) 

organisms. 

Flow path—An underground route for ground-water movement, extending 

from a recharge (intake) zone to a discharge (output) zone such as a 

shallow stream. 

Ground water—In general, any water that exists beneath the land surface, 

but more commonly applied to water in fully saturated soils and geologic formations. 

Herbicide—A chemical or other agent applied for the purpose of killing 

undesirable plants. See also Pesticide. 

Insecticide—A substance or mixture of substances intended to destroy or 

repel insects. 

Intolerant organisms—Organisms that are not adaptable to human alterations to the environment and thus decline in numbers where human 

alterations occur. 

Invertebrate—An animal having no backbone or spinal column. 

Major ions—Constituents commonly present in concentrations exceeding 

1.0 milligram per liter. Dissolved cations generally are calcium, magnesium, sodium, and potassium; the major anions are sulfate, chloride, fluoride, nitrate, and those contributing to alkalinity, most 

generally assumed to be bicarbonate and carbonate. 

Maximum contaminant level (MCL)—Maximum permissible level of a 

contaminant in water that is delivered to any user of a public water 

system. MCLs are enforceable standards established by the U.S. 

Environmental Protection Agency. 

Median—The middle or central value in a distribution of data ranked in 

order of magnitude. The median is also known as the 50th percentile. 

Metamorphic rock—Rock that has formed in the solid state in response to 

pronounced changes of temperature, pressure, and chemical environment. 

Method detection limit—The minimum concentration of a substance that 

can be accurately identified and measured with present laboratory 

technologies.

Micrograms per liter (μg/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. 

Minimum reporting level (MRL)—The smallest measured concentration 

of a constituent that may be reliably reported using a given analytical 

method. In many cases, the MRL is used when documentation for the 

method detection limit is not available. 

Monitoring well—A well designed for measuring water levels and testing 

ground-water quality. 

Nitrate—An ion consisting of nitrogen and oxygen (NO3

–

). Nitrate is a 

plant nutrient and is very mobile in soils. 

Nutrient—Element or compound essential for animal and plant growth. 

Common nutrients in fertilizer include nitrogen, phosphorus, and 

potassium. 

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

to control weeds, insects, fungi, nematodes, rodents or other "pests." 

Phosphorus—A nutrient essential for growth that can play a key role in 

stimulating aquatic growth in lakes and streams. 

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. 

Trace element—An element found in only minor amounts (concentrations 

less than 1.0 milligram per liter) in water or sediment; includes 

arsenic, cadmium, chromium, copper, lead, mercury, nickel, and zinc. 

Unconfined aquifer—An aquifer whose upper surface is a water table; an 

aquifer containing unconfined ground water. 

Volatile organic compounds (VOCs)—Organic chemicals that have a high 

vapor pressure relative to their water solubility. VOCs include components of gasoline, fuel oils, and lubricants, as well as organic solvents, fumigants, some inert ingredients in pesticides, and some byproducts of chlorine disinfection. 

Water table—The point below the land surface where ground water is first 

encountered and below which the earth is saturated. Depth to the 

water table varies widely across the country. 
Major Findings 25 

REFERENCES 

Abrahamsen, T.A., 1999, Trace elements in bed sediments and 

biota from streams in the Santee River Basin and coastal 

drainages, North and South Carolina, 1995–97: U.S. Geological Survey Water-Resources Investigations Report 99–4179, 

26 p.

Aucott,W.R., Davis, M.E., and Speiran, G.K., 1987, Geohydrologic 

framework of the Coastal Plain aquifers of South Carolina: 

U.S. Geological Survey Water-Resources Investigations 

Report 85-4271, 7 sheets.

Bahls, L.R., Burkantis, R., and Tralles, S., 1992, Benchmark biology of Montana reference streams: Department of Health and 

Environmental Science, Water Quality Bureau, Helena, 

Mont., 47 p.

Barbash, J.E., and Resek, E.A., 1996, Pesticides in ground water: 

Distribution, trends, and governing factors, v. 2—Pesticides in 

the hydrologic system: Chelsea, Mich., Ann Arbor Press, 

590 p. 

Canadian Council of Ministers of the Environment, 1995, Protocol 

for the derivation of Canadian sediment quality guidelines for 

the protection of aquatic life: Report CCME EPC–98E, 38 p.

Code of Federal Regulations, 1996, Title 40 Protection of the environment, chapter 1: Environmental Protection Agency, Part 

401, Section 401.15, Toxic Pollutants.

Fenneman, N.M., 1946, Physical divisions of the United States: 

Washington, D.C., U.S. Geological Survey special map, scale 

1:7,000,000.

Krabbenhoft, D.P., Wiener, J.G., Brumbaugh, W.G., Olson, M.L., 

DeWild, J.F., and Sabin, T.J., 1999, A national pilot study of 

mercury contamination of aquatic ecosystems along multiple 

gradients, in Morganwalp, D.W., and Buxton, H.T., eds., 

1999, U.S. Geological Survey Toxic Substances Hydrology 

Program—Proceedings of the Technical Meeting, Charleston, 

S.C., March 8–12, 1999, v. 2—Contamination of hydrologic 

systems and related ecosystems: U.S. Geological Survey 

Water-Resources Investigations Report 99–4018-B, p. 147–

160. 

Lindsey, Ginny, and Lewis, Ann, 1994, The rainbow river—Stain 

on the Piedmont: Asheville, N.C., Clean Water Fund of North 

Carolina, 52 p.

Litke, D.W., 1999, Review of phosphorus control measures in the 

United States and their effects on water quality: U.S. Geological Survey Water-Resources Investigations Report 99–4007, 

38 p. 

Lopes, T.J., 1998, Nonpoint sources of volatile organic compounds 

in urban areas—Relative importance of urban land surfaces 

and air: Environmental Pollution, v. 101, p. 221–230.

Lopes, T.J., Fallon, J.D, and Maluk, T.L., 2000, Compositing water 

samples for analysis of volatile organic compounds: Journal 

of Environmental Engineering, v. 126, no. 8, p. 769–773.

Maluk, T.L., 1999, Pesticides and bacteria in an urban 

stream—Gills Creek, Columbia, South Carolina: U.S. Geological Survey Fact Sheet FS–131–98, 4 p.

Maluk, T.L. and Abrahamsen, 1999, Results of water-quality sampling and ecological characterization of streams of Congaree 

Swamp, South Carolina 1995-98: U.S. Geological Survey 

Water-Resources Investigation Report 99-4121, 76 p.

Maluk, T.L., and Kelley, R.E, II, 1998, Pesticides in surface waters 

of the Santee River Basin and coastal drainages, North and 

South Carolina: U.S. Geological Survey Fact Sheet FS–007–

98, 6 p.

Maluk, T.L., Reuber, E.J., and Hughes, W.B., 1998, Nutrients in 

waters of the Santee River Basin and coastal drainages, North 

and South Carolina, 1973–93: U.S. Geological Survey WaterResources Investigations Report 97–4172, 60 p.

Nolan, B.T., and Stoner, J.D., 2000, Nutrients in ground waters of 

the conterminous United States 1992–1995: Environmental 

Science and Technology, v. 34, no. 7, p. 1156–1165.

Plafkin, J.L., Barbour, M.T., Porter, K.D., Gross, S.K., and Hughes, 

R.M., 1989, Rapid bioassessment protocols for use in streams 

and rivers: USEPA/440/4–89–001, variously paged.

Reuber, E.J., 1999, Shallow ground-water quality in the Coastal 

Plain of Columbia, South Carolina, 1996: U.S. Geological 

Survey Fact Sheet FS–130–98, 6 p.

Smock, L.A., and Gilinsky, Ellen, 1992, Coastal Plain blackwater 

streams, in Hackney, C.T., Adams, S.M., and Marshall, W.H., 

eds., Biodiversity of the southeastern United States aquatic 

communities: New York, John Wiley, p. 271–313.

South Carolina Agricultural Statistics Service, 1999, South Carolina Agricultural Statistics—Crops, livestock, poultry 1997–

1999: Columbia, South Carolina Agricultural Statistics Service, 84 p.

South Carolina Department of Health and Environmental Control, 

1992, Water classifications and standards (Regulation 61–68): 

South Carolina Department of Health and Environmental 

Control, 35 p.

_____ 2000, Fish consumption advisory tables: accessed May 25, 

2000, at http://www.state.sc.us/dhec/eqc/

South Carolina Water Resources Commission, 1983, South Carolina State Water Assessment: South Carolina Water Resources 

Commission Report No. 140, 367 p.

Stecker, K.K., and Crocker, Michael, 1991, South Carolina lake 

classification survey: South Carolina Department of Health 

and Environmental Control Technical Report No. 006–91, 

509 p.

U.S. Environmental Protection Agency, 1996, Drinking water regulation and health advisories: U.S. Environmental Protection 

Agency report EPA–822B–96/002, 11 p.

_____ 1999, Proposed radon in drinking water rule: U.S. Environmental Protection Agency Fact Sheet EPA 815–F—99–006,

7 p.

_____ 1986, Quality criteria for water—1986: U.S. Environmental 

Protection Agency report EPA 440/5–86–002 (variously 

paged).

_____ 1998, Update—Listing of fish and wildlife advisories: U.S. 

Environmental Protection Agency, LFWA Fact Sheet EPA–

823—98–009, 4 p.

U.S. Geological Survey, 1999, The quality of our Nation’s 

waters—Nutrients and pesticides: U.S. Geological Survey 

Circular 1225, 82 p.

Wilhelm, L.J., and Maluk, T.L., 1998, Fecal-indicator bacteria in 

surface waters of the Santee River Basin and coastal drainages, North and South Carolina, 1995–98: U.S. Geological 

Survey Fact Sheet FS–085–98, 6 p.
26 Water Quality in the Santee River Basin and Coastal Drainages

Streams in agricultural areas 

Streams in urban areas

Streams and rivers draining mixed land uses 

Shallow ground water in agricultural areas

Shallow ground water in urban areas 

Major aquifers 

Detected concentration in Study Unit

Frequencies of detection, in percent. Detection frequencies 

were not censored at any common reporting limit. The lefthand column is the study-unit frequency and the right-hand 

column is the national frequency 

Not measured or sample size less than two

Study-unit sample size. For ground water, the number of 

samples is equal to the number of wells sampled

National ranges of detected concentrations, by land use, in 36 

NAWQA Study Units, 1991–98—Ranges include only samples

in which a chemical was detected

Drinking-water quality (applies to ground water and surface water)

Protection of aquatic life (applies to surface water only)

Prevention of eutrophication in streams not flowing directly into 

lakes or impoundments

No benchmark for drinking-water quality

No benchmark for protection of aquatic life

*

**

66 38

Other herbicides detected

Acifluorfen (Blazer, Tackle 2S) **

Benfluralin (Balan, Benefin, Bonalan) * **

Bentazon (Basagran, Bentazone) **

Bromacil (Hyvar X, Urox B, Bromax) 

Butylate (Sutan +, Genate Plus, Butilate) **

CHEMICALS IN WATER

Concentrations and detection frequencies, Santee River Basin 

and coastal drainages, 1995–98—Detection sensitivity varies 

among chemicals and, thus, frequencies are not directly comparable 

Lowest

25 percent

Middle

50 percent

Highest

25 percent

National water-quality benchmarks

National benchmarks include standards and guidelines related to 

drinking-water quality, criteria for protecting the health of aquatic life, and 

a goal for preventing stream eutrophication due to phosphorus. Sources 

include the U.S. Environmental Protection Agency and the Canadian 

Council of Ministers of the Environment

|

|

|

--

This appendix is a summary of chemical concentrations 

and biological indicators assessed in the Santee River 

Basin and coastal drainages. Selected results for this 

Study Unit are graphically compared to results from as 

many as 36 NAWQA Study Units investigated from 1991 to 

1998 and to national water-quality benchmarks for human 

health, aquatic life, or fish-eating wildlife. The chemical and 

biological indicators shown were selected on the basis of 

frequent detection, detection at concentrations above a 

national benchmark, or regulatory or scientific importance. 

The graphs illustrate how conditions associated with each 

land use sampled in the Santee River Basin and coastal 

drainages compare to results from across the Nation, and 

how conditions compare among the several land uses. 

Graphs for chemicals show only detected concentrations 

and, thus, care must be taken to evaluate detection 

frequencies in addition to concentrations when comparing 

study-unit and national results. For example, tebuthiuron 

concentrations in Santee River Basin and coastal 

drainages agricultural streams were similar to the national 

distribution, but the detection frequency was much higher 

(66 percent compared to 22 percent). 

CONCENTRATION, IN MICROGRAMS PER LITER

 0.0001 0.001 0.01 0.1 1 10 100 1,000 

Study-unit frequency of detection, in percent

National frequency of detection, in percent

Pesticides in water—Herbicides

Study-unit sample size

12

Alachlor (Lasso, Bronco, Lariat, Bullet) **

55 44 | 53 14 20 | 43 17 45 | 18

3 3 | 30 0 <1 | 28 2 1 | 88

Atrazine (AAtrex, Atrex, Atred, Gesaprim) 

96 88 | | 53 98 86 | | 43 72 87 | | 18

50 40 | 30 57 30 | 28 10 18 | 88

2,4-D (Aqua-Kleen, Lawn-Keep, Weed-B-Gone) 4 15 | | 28 9 18 | | 33 0 11 | | 15

0 <1 | 30 0 1 | 28 0 <1 | 87

Deethylatrazine (Atrazine breakdown product) * ** 77 75 53 93 62 43 44 75 18

60 39 30 43 28 28 10 19 88

Dinoseb (Dinosebe) 

0 <1 | | 28

0 1 | 30

2 <1 | 87

Metolachlor (Dual, Pennant) 

96 81 | | 53 28 64 | | 43 67 83 | | 18

17 18 | 30 0 9 | 28 2 5 | 88

Prometon (Pramitol, Princep) **

57 44 | 53 95 86 | 43 33 60 | 18

3 12 | 30 7 21 | 28 1 5 | 88

Simazine (Princep, Caliber 90) 81 61 | | 53 98 77 | | 43 61 74 | | 18

7 21 | 30 39 18 | 28 3 5 | 88

Tebuthiuron (Spike, Tebusan) 

66 22 | | 53 98 39 | | 43 94 32 | | 18

7 3 | 30 11 7 | 28 5 3 | 88

APPENDIX—WATER-QUALITY DATA FROM THE SANTEE RIVER 

BASIN AND COASTAL DRAINAGES IN A NATIONAL CONTEXT

For a complete view of Santee River Basin and coastal drainages data and for additional information about specific benchmarks used, visit our Web site at 

http://water.usgs.gov/nawqa/. Also visit the NAWQA Data Warehouse for access to NAWQA data sets at http://water.usgs.gov/nawqa/data. 
Water-Quality Data in a National Context 27 

CONCENTRATION, IN MICROGRAMS PER LITER

 0.0001 0.001 0.01 0.1 1 10 100 1,000 

Cyanazine (Bladex, Fortrol) 

DCPA (Dacthal, chlorthal-dimethyl) * **

2,6-Diethylaniline (Alachlor breakdown product) * **

Diuron (Crisuron, Karmex, Diurex) **

EPTC (Eptam, Farmarox, Alirox) * **

Ethalfluralin (Sonalan, Curbit) * **

Fenuron (Fenulon, Fenidim) * **

Fluometuron (Flo-Met, Cotoran) **

Linuron (Lorox, Linex, Sarclex, Linurex, Afalon) * 

Metribuzin (Lexone, Sencor) 

Molinate (Ordram) * **

Neburon (Neburea, Neburyl, Noruben) * **

Norflurazon (Evital, Predict, Solicam, Zorial) * **

Oryzalin (Surflan, Dirimal) * **

Pendimethalin (Pre-M, Prowl, Stomp) * **

Pronamide (Kerb, Propyzamid) **

Propham (Tuberite) **

Terbacil (Sinbar) **

Trifluralin (Treflan, Gowan, Tri-4, Trific)

Herbicides not detected

Acetochlor (Harness Plus, Surpass) * **

Bromoxynil (Buctril, Brominal) * 

Chloramben (Amiben, Amilon-WP, Vegiben) **

Clopyralid (Stinger, Lontrel, Transline) * **

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

Dacthal mono-acid (Dacthal breakdown product) * **

Dicamba (Banvel, Dianat, Scotts Proturf) 

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

MCPA (Rhomene, Rhonox, Chiptox) 

MCPB (Thistrol) * **

Napropamide (Devrinol) * **

Pebulate (Tillam, PEBC) * **

Picloram (Grazon, Tordon) 

Propachlor (Ramrod, Satecid) **

Propanil (Stam, Stampede, Wham) * **

2,4,5-T **

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

Thiobencarb (Bolero, Saturn, Benthiocarb) * **

Triallate (Far-Go, Avadex BW, Tri-allate) * 

Triclopyr (Garlon, Grandstand, Redeem, Remedy) * **

Study-unit frequency of detection, in percent

National frequency of detection, in percent

Pesticides in water—Insecticides

Study-unit sample size

Volatile organic compounds (VOCs) in ground water

These graphs represent data from 16 Study Units, sampled from 1996 to 1998

Study-unit frequency of detection, in percent

National frequency of detection in percent Study-unit sample size

CONCENTRATION, IN MICROGRAMS PER LITER

 0.001 0.01 0.1 1 10 100 1,000 10,000 

Other insecticides detected 

Aldicarb (Temik, Ambush, Pounce) 

Aldicarb sulfone (Standak, aldoxycarb) 

Carbofuran (Furadan, Curaterr, Yaltox) 

Fonofos (Dyfonate, Capfos, Cudgel, Tycap) **

3-Hydroxycarbofuran (Carbofuran breakdown product) * **

Methiocarb (Slug-Geta, Grandslam, Mesurol) * **

Methomyl (Lanox, Lannate, Acinate) **

Oxamyl (Vydate L, Pratt) **

cis-Permethrin (Ambush, Astro, Pounce) * **

Propoxur (Baygon, Blattanex, Unden, Proprotox) * **

Insecticides not detected

Azinphos-methyl (Guthion, Gusathion M) * 

Disulfoton (Disyston, Di-Syston) **

Ethoprop (Mocap, Ethoprophos) * **

alpha-HCH (alpha-BHC, alpha-lindane) **

gamma-HCH (Lindane, gamma-BHC) 

Methyl parathion (Penncap-M, Folidol-M) **

Phorate (Thimet, Granutox, Geomet, Rampart) * **

Propargite (Comite, Omite, Ornamite) * **

Terbufos (Contraven, Counter, Pilarfox) **

Aldicarb sulfoxide (Aldicarb breakdown product) 

3 <1 | | 29

0 <1 | 30

1 <1 | 85

Carbaryl (Carbamine, Denapon, Sevin) 

9 9 | | 53 51 46 | | 43 0 16 | | 18

0 <1 | 30 11 2 | 28 0 1 | 88

Chlorpyrifos (Brodan, Dursban, Lorsban) 60 18 | | 53 72 37 | | 43 0 20 | | 18

0 1 | 30 7 1 | 28 0 <1 | 88

p,p'-DDE 

2 8 | | 53 0 2 | | 43 6 4 | | 18

0 4 | 30 0 2 | 28 2 2 | 88

Diazinon (Basudin, Diazatol, Neocidol, Knox Out) 

6 16 | | 53 81 70 | | 43 0 39 | | 18

3 <1 | 30 11 2 | 28 1 2 | 88

Dieldrin (Panoram D-31, Octalox, Compound 497) 

2 6 | | 53 0 2 | | 43 0 2 | | 18

3 1 | 30 25 6 | 28 1 1 | 88

Malathion (Malathion) 9 5 | | 53 56 21 | | 43 11 6 | | 18

0 <1 | 30 0 <1 | 28 0 <1 | 88

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

4 <1 | 53 5 1 | 43 0 <1 | 18

CONCENTRATION, IN MICROGRAMS PER LITER

 0.0001 0.001 0.01 0.1 1 10 100 1,000 

Study-unit frequency of detection, in percent

National frequency of detection, in percent Study-unit sample size

1 Carbon disulfide *

-- 30 0 83 42 30 24 24 90
28 Water Quality in the Santee River Basin and Coastal Drainages

CONCENTRATION, IN MILLIGRAMS PER LITER

 0.001 0.01 0.1 1 10 100 1,000 10,000 100,000 

Nutrients in water

Study-unit frequency of detection, in percent

National frequency of detection, in percent Study-unit sample size

Chloromethane (Methyl chloride) 1 

-- 20 | 0 63 22 | 30 2 15 | 90

Methyl tert-butyl ether (MTBE) 

-- 4 | 0 23 16 | 30 3 6 | 90

Trichloroethene (TCE) 

-- 3 | 0 27 8 | 30 2 5 | 90

Trichloromethane (Chloroform) 1 

-- 35 | 0 73 51 | 30 46 30 | 90

Study-unit frequency of detection, in percent

National frequency of detection in percent Study-unit sample size

CONCENTRATION, IN MICROGRAMS PER LITER

 0.001 0.01 0.1 1 10 100 1,000 10,000 

Other VOCs detected

tert-Amylmethylether (tert-amyl methyl ether (TAME)) * 

Benzene 

Bromodichloromethane (Dichlorobromomethane) 

Bromomethane (Methyl bromide) 

2-Butanone (Methyl ethyl ketone (MEK)) * 

sec-Butylbenzene * 

tert-Butylbenzene * 

Chlorobenzene (Monochlorobenzene) 

Chlorodibromomethane (Dibromochloromethane) 

Chloroethane (Ethyl chloride) * 

Chloroethene (Vinyl chloride) 

1,2-Dichlorobenzene (o-Dichlorobenzene) 

1,3-Dichlorobenzene (m-Dichlorobenzene) 

1,4-Dichlorobenzene (p-Dichlorobenzene) 

Dichlorodifluoromethane (CFC 12, Freon 12) 

1,2-Dichloroethane (Ethylene dichloride) 

1,1-Dichloroethane (Ethylidene dichloride) * 

1,1-Dichloroethene (Vinylidene chloride) 

trans-1,2-Dichloroethene ((E)-1,2-Dichlorothene) 

cis-1,2-Dichloroethene ((Z)-1,2-Dichloroethene) 

Dichloromethane (Methylene chloride) 

1,2-Dichloropropane (Propylene dichloride) 

Diethyl ether (Ethyl ether) * 

1,2-Dimethylbenzene (o-Xylene) 

1,3 & 1,4-Dimethylbenzene (m-&p-Xylene) 

1-4-Epoxy butane (Tetrahydrofuran, Diethylene oxide) * 

Ethylbenzene (Phenylethane) 

Iodomethane (Methyl iodide) * 

Isopropylbenzene (Cumene) * 

p-Isopropyltoluene (p-Cymene) * 

Methylbenzene (Toluene) 

2-Propanone (Acetone) * 

1,1,2,2-Tetrachloroethane * 

Tetrachloroethene (Perchloroethene) 

Tetrachloromethane (Carbon tetrachloride) 

1,2,3,5-Tetramethylbenzene (Isodurene) * 

Tribromomethane (Bromoform) 

1,1,1-Trichloroethane (Methylchloroform) 

Trichlorofluoromethane (CFC 11, Freon 11) 

VOCs not detected

Bromobenzene (Phenyl bromide) * 

Bromochloromethane (Methylene chlorobromide) 

Bromoethene (Vinyl bromide) * 

n-Butylbenzene (1-Phenylbutane) * 

3-Chloro-1-propene (3-Chloropropene) * 

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

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

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

1,2-Dibromoethane (Ethylene dibromide, EDB) 

Dibromomethane (Methylene dibromide) * 

trans-1,4-Dichloro-2-butene ((Z)-1,4-Dichloro-2-butene) * 

2,2-Dichloropropane * 

1,3-Dichloropropane (Trimethylene dichloride) * 

trans-1,3-Dichloropropene ((E)-1,3-Dichloropropene) 

cis-1,3-Dichloropropene ((Z)-1,3-Dichloropropene) 

1,1-Dichloropropene * 

Diisopropyl ether (Diisopropylether (DIPE)) * 

Ethenylbenzene (Styrene) 

Ethyl methacrylate * 

Ethyl tert-butyl ether (Ethyl-t-butyl ether (ETBE)) * 

1-Ethyl-2-methylbenzene (2-Ethyltoluene) * 

Hexachlorobutadiene 

1,1,1,2,2,2-Hexachloroethane (Hexachloroethane) 

2-Hexanone (Methyl butyl ketone (MBK)) * 

Methyl acrylonitrile * 

Methyl-2-methacrylate (Methyl methacrylate) * 

4-Methyl-2-pentanone (Methyl isobutyl ketone (MIBK)) * 

Methyl-2-propenoate (Methyl acrylate) * 

Naphthalene 

2-Propenenitrile (Acrylonitrile) 

n-Propylbenzene (Isocumene) * 

1,1,1,2-Tetrachloroethane 

1,2,3,4-Tetramethylbenzene (Prehnitene) * 

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

1,2,4-Trichlorobenzene 

1,2,3-Trichlorobenzene * 

1,1,2-Trichloroethane (Vinyl trichloride) 

1,2,3-Trichloropropane (Allyl trichloride) 

1,2,3-Trimethylbenzene (Hemimellitene) * 

1,2,4-Trimethylbenzene (Pseudocumene) * 

1,3,5-Trimethylbenzene (Mesitylene) * 

1 Many of the samples in this study were diluted prior to laboratory analysis and therefore the 

actual detection frequency may be larger than the value listed.

Ammonia, as N * **

76 84 111 86 86 102 64 75 181

27 78 30 73 71 30 64 70 89

Dissolved ammonia plus organic nitrogen, as N * ** 52 78 111 69 74 102 77 62 181

7 28 30 17 30 30 25 24 89

Dissolved nitrite plus nitrate, as N ** 100 95 | 111 94 97 | 102 83 91 | 181

87 81 | 30 87 74 | 30 60 71 | 89
Water-Quality Data in a National Context 29 

Fish tissue from streams in agricultural areas

Fish tissue from streams in urban areas

Fish tissue from streams draining mixed land uses

Sediment from streams in agricultural areas 

Sediment from streams in urban areas 

Sediment from streams draining mixed land uses

Protection of fish-eating wildlife (applies to fish tissue)

Protection of aquatic life (applies to bed sediment)

No benchmark for protection of fish-eating wildlife

No benchmark for protection of aquatic life

|

|

**

CHEMICALS IN FISH TISSUE

AND BED SEDIMENT

Concentrations and detection frequencies, Santee River Basin 

and coastal drainages, 1995–98—Detection sensitivity varies among 

chemicals and, thus, frequencies are not directly comparable among 

chemicals. Study-unit frequencies of detection are based on small 

sample sizes; the applicable sample size is specified in each graph

Lowest

25 percent

Middle

50 percent

Highest

25 percent

National benchmarks for fish tissue and bed sediment

National benchmarks include standards and guidelines related to 

criteria for protection of the health of fish-eating wildlife and aquatic 

organisms. Sources include the U.S. Environmental Protection Agency, 

other Federal and State agencies, and the Canadian Council of 

Ministers of the Environment

*

CONCENTRATION, IN MICROGRAMS PER KILOGRAM

(Fish tissue is wet weight; bed sediment is dry weight)

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

National ranges of concentrations detected, by land use, in 36 

NAWQA Study Units, 1991–98—Ranges include only samples

in which a chemical was detected

Detected concentration in Study Unit

Frequencies of detection, in percent. Detection frequencies 

were not censored at any common reporting limit. The lefthand column is the study-unit frequency and the right-hand 

column is the national frequency

Not measured or sample size less than two

Study-unit sample size

66 38

--

12

Organochlorines in fish tissue (whole body)

and bed sediment

Study-unit frequency of detection, in percent

National frequency of detection, in percent Study-unit sample size

Other trace elements detected

Selenium 

Uranium 

Trace elements not detected

Cadmium 

CONCENTRATION, IN MILLIGRAMS PER LITER

 0.001 0.01 0.1 1 10 100 1,000 10,000 100,000 

Dissolved solids in water

Study-unit frequency of detection, in percent

National frequency of detection, in percent Study-unit sample size

CONCENTRATION, IN PICOCURIES PER LITER

Trace elements in ground water

Study-unit frequency of detection, in percent

National frequency of detection, in percent Study-unit sample size

CONCENTRATION, IN MILLIGRAMS PER LITER

 0.001 0.01 0.1 1 10 100 1,000 10,000 100,000 

Study-unit frequency of detection, in percent

National frequency of detection, in percent Study-unit sample size

Arsenic 

-- 58 | 0 -- 36 | 0 4 37 | 90

Chromium 

-- 85 | 0 -- 79 | 0 57 73 | 90

Lead 

-- 9 | 0 -- 5 | 0 37 16 | 90

Radon-222 

-- 99 | 0 -- 100 | 0 93 97 | 90

Zinc 

-- 28 | 0 -- 29 | 0 62 66 | 90

CONCENTRATION, IN MICROGRAMS PER LITER

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

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

Orthophosphate, as P * **

86 79 111 26 72 103 88 74 181

40 59 30 10 52 30 69 61 89

Total phosphorus, as P * ** 95 92 | 111 91 90 | 102 97 88 | 181

Dissolved solids * ** 100 100 111 100 100 103 100 100 179

100 100 30 100 100 30 100 100 90

Total Chlordane (sum of 5 chlordanes) 

-- 38 | 1 -- 75 | 1 100 56 | 2

0 9 | 7 67 57 | 3 0 11 | 8

o,p'+p,p'-DDD (sum of o,p'-DDD and p,p'-DDD) * 

-- 49 1 -- 69 1 50 50 2

29 27 | 7 33 50 | 3 12 20 | 8
30 Water Quality in the Santee River Basin and Coastal Drainages

CONCENTRATION, IN MICROGRAMS PER KILOGRAM, DRY WEIGHT

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

Study-unit frequency of detection, in percent

National frequency of detection, in percent

Semivolatile organic compounds (SVOCs)

in bed sediment

Study-unit sample size

Other organochlorines detected

DCPA (Dacthal, chlorthal-dimethyl) * **

o,p'+p,p'-DDT (sum of o,p'-DDT and p,p'-DDT) * 

Heptachlor epoxide (Heptachlor breakdown product) * 

Hexachlorobenzene (HCB) **

Mirex (Dechlorane) **

Organochlorines not detected

Chloroneb (Chloronebe, Demosan) * **

Endosulfan I (alpha-Endosulfan, Thiodan) * **

Endrin (Endrine) 

gamma-HCH (Lindane, gamma-BHC, Gammexane) * 

Total-HCH (sum of alpha-HCH, beta-HCH, gamma-HCH, and 

delta-HCH) **

Isodrin (Isodrine, Compound 711) * **

p,p'-Methoxychlor (Marlate, methoxychlore) * **

o,p'-Methoxychlor * **

cis-Permethrin (Ambush, Astro, Pounce) * **

trans-Permethrin (Ambush, Astro, Pounce) * **

Toxaphene (Camphechlor, Hercules 3956) * **

CONCENTRATION, IN MICROGRAMS PER KILOGRAM

(Fish tissue is wet weight; bed sediment is dry weight)

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

Study-unit frequency of detection, in percent

National frequency of detection, in percent Study-unit sample size

2 The national detection frequencies for total PCB in sediment are biased low because about 

30 percent of samples nationally had elevated detection levels compared to this Study Unit. 

See http://water.usgs.gov/nawqa/ for additional information.

p,p'-DDE * ** -- 90 1 -- 94 1 100 92 3

71 48 7 33 62 3 62 39 8

o,p'+p,p'-DDE (sum of o,p'-DDE and p,p'-DDE) * -- 90 1 -- 94 1 100 92 2

71 48 | 7 33 62 | 3 62 39 | 8

Total DDT (sum of 6 DDTs) **

-- 90 | 1 -- 94 | 1 100 93 | 2

71 49 7 33 66 3 62 41 8

Dieldrin (Panoram D-31, Octalox) * 

-- 53 1 -- 42 1 67 38 3

0 13 | 7 33 30 | 3 0 9 | 8

Dieldrin+aldrin (sum of dieldrin and aldrin) **

-- 52 | 1 -- 42 | 1 50 38 | 2

0 13 7 33 29 3 0 9 8

Heptachlor+heptachlor epoxide ** -- 9 | 1 -- 9 | 1 50 14 | 2

0 1 7 0 2 3 0 <1 8

Total PCB 2

-- 38 | 1 -- 81 | 1 100 66 | 2

0 2 | 7 0 21 | 3 0 9 | 8

Acenaphthene 

14 10 | 7 33 54 | 3 50 27 | 8

Anthracene 

43 37 | 7 100 89 | 3 88 56 | 8

Anthraquinone **

14 21 7 100 83 3 62 39 8

9H-Carbazole **

14 19 7 100 76 3 50 33 8

Dibenzothiophene **

29 12 7 67 64 3 62 30 8

1,4-Dichlorobenzene (p-Dichlorobenzene) **

0 6 3 12 7 8

2,6-Dimethylnaphthalene **

57 65 7 67 74 3 62 77 8

bis(2-Ethylhexyl)phthalate **

100 91 7 100 99 3 100 95 8

Fluoranthene 

100 66 | 7 100 97 | 3 88 78 | 8

9H-Fluorene (Fluorene) 

14 22 | 7 67 76 | 3 75 41 | 8
Water-Quality Data in a National Context 31 

CONCENTRATION, IN MICROGRAMS PER GRAM

(Fish tissue is wet weight, bed sediment is dry weight)

 0.01 0.1 1 10 100 10,000 1,000 

Study-unit frequency of detection, in percent

National frequency of detection, in percent

Trace elements in fish tissue (livers) and 

bed sediment

Study-unit sample size

CONCENTRATION, IN MICROGRAMS PER KILOGRAM, DRY WEIGHT

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

Study-unit frequency of detection, in percent

National frequency of detection, in percent Study-unit sample size

Other SVOCs detected

Acenaphthylene 

Acridine **

Benz[a]anthracene 

Benzo[a]pyrene 

Benzo[b]fluoranthene **

Benzo[ghi]perylene **

Benzo[k]fluoranthene **

Butylbenzylphthalate **

Chrysene 

p-Cresol **

Di-n-butylphthalate **

Di-n-octylphthalate **

Dibenz[a,h]anthracene 

Diethylphthalate **

1,2-Dimethylnaphthalene **

1,6-Dimethylnaphthalene **

Dimethylphthalate **

2-Ethylnaphthalene **

Indeno[1,2,3-cd]pyrene **

Isoquinoline **

1-Methyl-9H-fluorene **

2-Methylanthracene **

4,5-Methylenephenanthrene **

1-Methylphenanthrene **

1-Methylpyrene **

Naphthalene 

Phenanthridine **

Quinoline **

2,3,6-Trimethylnaphthalene **

SVOCs not detected

C8-Alkylphenol **

Azobenzene **

Benzo[c]cinnoline **

2,2-Biquinoline **

4-Bromophenyl-phenylether **

4-Chloro-3-methylphenol **

bis(2-Chloroethoxy)methane **

2-Chloronaphthalene **

2-Chlorophenol **

4-Chlorophenyl-phenylether **

1,2-Dichlorobenzene (o-Dichlorobenzene) **

1,3-Dichlorobenzene (m-Dichlorobenzene) **

3,5-Dimethylphenol **

2,4-Dinitrotoluene **

Isophorone **

Nitrobenzene **

N-Nitrosodi-n-propylamine **

Pentachloronitrobenzene **

1,2,4-Trichlorobenzene **

N-Nitrosodiphenylamine **

0 2 7 33 10 3 0 4 8

Phenanthrene 

71 50 | 7 100 93 | 3 75 66 | 8

Phenol **

100 81 7 100 82 3 88 80 8

Pyrene 

86 64 | 7 100 95 | 3 88 76 | 8

Arsenic * 

-- 56 1 -- 38 1 100 76 4

100 99 | 7 100 98 | 3 100 97 | 7

Cadmium * 

-- 77 1 -- 72 1 100 95 4

100 98 | 7 100 100 | 3 100 98 | 7

Chromium * -- 62 1 -- 72 1 50 54 4

100 100 | 7 100 99 | 3 100 100 | 7

Copper * -- 100 1 -- 100 1 100 100 4

100 100 | 7 100 99 | 3 100 100 | 7

Lead * 

-- 11 1 -- 41 1 50 41 4

100 100 | 7 100 100 | 3 100 99 | 7

Mercury * 

-- 71 1 -- 59 1 75 80 4

100 82 | 7 100 97 | 3 100 93 | 7

Nickel * **

-- 42 1 -- 44 1 0 50 4

100 100 7 100 100 3 100 100 7

Selenium * -- 99 1 -- 100 1 100 99 4

100 100 | 7 100 100 | 3 100 100 | 7
32 Water Quality in the Santee River Basin and Coastal Drainages

Study-unit frequency of detection, in percent

National frequency of detection, in percent

Biological indicator value, Santee River Basin and coastal 

drainages, by land use, 1995–98

Biological status assessed at a site

National ranges of biological indicators, in 16 NAWQA Study 

Units, 1994–98

Streams in undeveloped areas

Streams in agricultural areas

Streams in urban areas

Streams in mixed-land-use areas

75th percentile

25th percentile

BIOLOGICAL INDICATORS

Higher national scores suggest habitat disturbance, water-quality 

degradation, or naturally harsh conditions. The status of algae, 

invertebrates (insects, worms, and clams), and fish provide a 

record of water-quality and stream conditions that waterchemistry indicators may not reveal. Algal status focuses on the 

changes in the percentage of certain algae in response to 

increasing siltation, and it often correlates with higher nutrient 

concentrations in some regions. Invertebrate status averages 11 

metrics that summarize changes in richness, tolerance, trophic 

conditions, and dominance associated with water-quality 

degradation. Fish status sums the scores of four fish metrics 

(percent tolerant, omnivorous, non-native individuals, and percent 

individuals with external anomalies) that increase in association 

with water-quality degradation

 0 10 20 30 40 50 60 70 80 90 100

CONCENTRATION, IN MICROGRAMS PER GRAM

(Fish tissue is wet weight, bed sediment is dry weight)

 0.01 0.1 1 10 100 10,000 1,000 

Study-unit sample size

 0 5 10 15 20

 Algal status indicator

Undeveloped

Agricultural

Urban

Mixed

 Invertebrate status indicator

Undeveloped

Agricultural

Urban

Mixed

 Fish status indicator

Undeveloped

Agricultural

Urban

Mixed

Zinc * 

-- 100 1 -- 100 1 100 100 4

100 100 | 7 100 99 | 3 100 100 | 7
A COORDINATED EFFORT

Coordination with agencies and organizations in the Santee River Basin and coastal drainages was integral to the 

success of this water-quality assessment. We thank those who served as members of our liaison committee. 

Federal Agencies

National Park Service, Congaree Swamp National 

Monument

Natural Resources Conservation Service

U.S. Army Corps of Engineers

U.S. Fish and Wildlife Service

U.S. Forest Service

State Agencies

North Carolina Department of Environment and 

Natural Resources

Ocean and Coastal Resource Management

South Carolina Department of Health and Environmental Control

South Carolina Department of Natural Resources

South Carolina Forestry Commission

South Carolina Geological Survey

South Carolina Sea Grant Consortium

South Carolina Water Resources Research Institute

Local Agencies

Catawba Regional Planning Council

Charlotte-Mecklenburg Utility Department

Gaston County Cooperative Extension Service

Greenville County Soil and Water Conservation 

District

Western Piedmont Council of Governments

Universities

Columbia College

South Carolina State University

University of North Carolina at Charlotte

University of South Carolina

Other public and private organizations

Catawba Nation

Clean Water Fund of North Carolina

Duke Energy

National Audubon Society

South Carolina Electric and Gas Company

South Carolina Rural Water Association

We thank the following individuals for contributing to this effort. 

Barbara Kleiss, Ted Campbell, and Sandra Cooper (USGS); Barry Beasley (South Carolina Department of Natural 

Resources); and Oscar Penegar (Environmental Advocate) for reviewing the report.

Jeannie Eidson (South Carolina Department of Environmental Control) for providing support and data for geographic information systems.

Larry Bradham (South Carolina Well Drillers Association) for assisting in locating wells for sampling.

Gary Taylor and Ralph Willoughby (South Carolina Geological Survey) for assisting in drilling wells.

The numerous property owners who allowed the USGS to install monitoring wells or sample existing wells on their 

property.

Ben Abercrombie, Boyce Blanks, Wade Bryant, Kristen Hein, Cliff Hupp, Robert Kelley, Donald Leary, Krystal Lynn, 

Brent Means, Larry Puckett, Whitney Stringfield, Robert Thorn, and Carlton Wood for providing invaluable technical and field support for the study.

Dick Christie (South Carolina Department of Natural Resources), Ginny Lindsey (North Carolina Clean Water 

Fund), and Charlie Zemp (South Carolina Department of Natural Resources) for providing guided tours of parts of 

the Santee Basin.

This report is dedicated to the memory of Don Leary; his quiet strength, hard work, and good humor helped make 

this study a success.
Hughes and others— W

U.S. Geological Survey Circular 1206

ater Quality in the Santee River Basin and Coastal Drainages

National Water-Quality Assessment (NAWQA) Program

Santee River Basin and Coastal Drainages

NAWQA

NORTH

CAROLINA

SOUTH

CAROLINA

Catawba R

Columbia

Charleston

Charlotte

Spartanburg

Greenville

Santee R

Edisto River

Broad River

Wateree R

Congaree R

Saluda R Atlantic

Ocean