Water Quality in the

Great and Little Miami River Basins

Ohio and Indiana, 1999–2001

U.S. Department of the Interior

U.S. Geological Survey

Circular 1229
Points of Contact and Additional Information

The companion Web site for NAWQA summary reports:

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

Other NAWQA summary reports

River Basin Assessments

Acadian-Pontchartrain Drainages (Circular 1232)

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)

Cook Inlet Basin (Circular 1240)

Delaware River Basin (Circular 1227)

Delmarva Peninsula (Circular 1228)

Eastern Iowa Basins (Circular 1210)

Georgia-Florida Coastal Plain (Circular 1151)

Great Salt Lake Basins (Circular 1236)

Hudson River Basin (Circular 1165)

Island of Oahu (Circular 1239)

Kanawha - New River Basins (Circular 1204)

Lake Erie - Lake Saint Clair Drainages (Circular 1203)

Long Island - New Jersey Coastal Drainages (Circular 1201)

Lower Illinois River Basin (Circular 1209)

Lower Susquehanna River Basin (Circular 1168)

Lower Tennessee River Basin (Circular 1233)

Las Vegas Valley Area and the Carson and Truckee River Basins (Circular 1170)

Mississippi Embayment (Circular 1208)

Mobile River Basin (Circular 1231)

New England Coastal Basins (Circular 1226)

Northern Rockies Intermontane Basins (Circular 1235)

Ozark Plateaus (Circular 1158)

Potomac River Basin (Circular 1166)

Puget Sound Basin (Circular 1216)

Red River of the North Basin (Circular 1169)

Rio Grande Valley (Circular 1162)

Sacramento River Basin (Circular 1215)

San Joaquin-Tulare Basins (Circular 1159)

Santa Ana Basin (Circular 1238)

Santee River Basin and Coastal Drainages (Circular 1206)

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 Illinois River Basin (Circular 1230)

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)

Yakima River Basin (Circular 1237)

Yellowstone River Basin (Circular 1234)

National Assessments

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

Great and Little Miami River Basins contact and 

Web site:

USGS State Representative

U.S. Geological Survey

Water Resources Discipline

6480 Doubletree Ave.

Columbus, Ohio 43229–1111

e-mail: jrmorris@usgs.gov

http://oh.water.usgs.gov/miam/intro.html

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/

Front cover: The Little Miami River near Mason, Ohio (photograph by Eric Hatch Photography, Loveland, Ohio). Back cover: Left, Dayton skyline 

(photograph by Richard Baumer, published with permission); Middle, Little Miami River, near Mason, Ohio, after a summer rainstorm (photograph by Eric Hatch Photography, Loveland, Ohio); Right, municipal supply well near Fairfield, Ohio (photograph by Rhett Moore, U.S. Geological 

Survey).
Water Quality in the 

Great and Little Miami River Basins, 

Ohio and Indiana, 1999–2001

By Gary L. Rowe, Jr., David C. Reutter, Donna L. Runkle, 

Julie A. Hambrook, Stephanie D. Janosy, and Lee H. Hwang

Circular 1229

U.S. Department of the Interior

U.S. Geological Survey
Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Library of Congress Cataloging-in-Publication Data

Water Quality in the Great and Little Miami River Basins, Ohio and Indiana, 1999-2001 / 

 by Gary L. Rowe...[et al.].

 p. cm. -- (Circular ; 1229)

 Includes bibliographic references.

 ISBN 0-607-96403-0 (alk. paper)

 1. Water quality--Ohio--Great Miami River Watershed. 2. Water quality--Ohio--Little Miami 

River Watershed. 3. Water quality--Indiana. 1. Rowe, Gary L., II. Geological Survey

(U.S.) III. U.S. Geological Survey circular ; 1229.

TN224.O3W34 2004

363.739’42’097717--dc22

2004041395

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

U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

Free on application to the U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS

World Wide Web: http://www.usgs.gov/

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement by the U.S. Government
Contents

National Water-Quality Assessment Program ......................................................... iv

What kind of water-quality information does the NAWQA Program provide? ............... v

Introduction to this Report .............................................................................. vi

Summary of Major Findings .............................................................................. 1

Introduction to the Great and Little Miami River Basins ............................................. 3

Major Findings ............................................................................................. 5

Pesticides .......................................................................................... 5

NATIONAL PERSPECTIVE—Pesticide occurrence in streams varied in response 

to ground-water contributions; pesticides in ground water were generally 

comparable to those in the rest of the Nation and Corn Belt region ......... 6

LOCAL PERSPECTIVE—Glyphosate was detected infrequently in streams and not 

found in ground water ............................................................... 9

LOCAL PERSPECTIVE—Atrazine concentrations in treated water from Harsha Lake 

met drinking-water standard ...................................................... 10

Other Organic Compounds ........................................................................ 13

 LOCAL PERSPECTIVE—Hydrogeologic setting, ground-water age, well depth, and 

construction are key to understanding water quality ................................. 14

NATIONAL PERSPECTIVE—Concentrations of PCBs in fish tissue were among the 

highest in the Nation ............................................................... 17

Naturally Occurring Trace Elements ............................................................ 16

NATIONAL PERSPECTIVE—Concentrations of mercury in water and sediment were 

lower than the national median, despite higher atmospheric deposition 

rates ................................................................................. 18

NATIONAL PERSPECTIVE—Proposed drinking-water standard for radon commonly 

was exceeded, but concentrations were similar to those in other glaciated 

areas ................................................................................. 18

Nutrients—Too Much of a Good Thing ......................................................... 19

NATIONAL PERSPECTIVE—Nutrients in mixed-land-use streams and nitrate in 

shallow agricultural wells were among the highest in the Nation. ............ 21

LOCAL PERSPECTIVE—Confined animal feeding operations (CAFOs) contributed 

additional nutrients and trace amounts of antibiotics to streams ............ 23

Influence of Urbanization on Stream Quality ................................................... 25

LOCAL PERSPECTIVE—Changes observed in the Fish Community, 1900–98 ......... 27

REGIONAL PERSPECTIVE—Stream quality degrades as urbanization increases in 

four major metropolitan areas ...................................................... 28

Study-Unit Design ....................................................................................... 29

References Cited .......................................................................................... 31

Glossary ................................................................................................... 33

Appendix—Water Quality Data from the Great and Little Miami River Basins in a 

National Context ................................................................................. 35
National Water-Quality Assessment Program

The quality of the Nation’s water resources is of great interest because it is so integrally linked 

to the long-term availability of water that is clean and safe for drinking and recreation and 

that is suitable for industry, irrigation, and habitat for fish and wildlife. Recognizing the need 

for long-term, nationwide assessments of water resources, the U.S. Congress has appropriated funds since 1991 for the USGS to conduct the National Water-Quality Assessment 

(NAWQA) Program. Scientists in the NAWQA Program work with partners in government, 

research, and public interest groups to assess the spatial extent of water-quality conditions, 

how water quality changes with time, and how human activities and natural factors affect water 

quality. This information is useful for guiding water-management and protection strategies, 

research, and monitoring in different hydrologic and land-use settings across the Nation.

The Great and Little Miami River Basins is one of 51 water-quality assessments initiated since 

1991. Together, the 51 major river basins and aquifer systems, referred to as “Study Units,” 

include water resources used by more than 60 percent of the population in watersheds that 

cover about half of the land area of the conterminous United States. Timing of the assessments 

varies because of the Program’s rotational design, in which one-third of all Study Units are 

intensively investigated for 3 to 4 years, with trends assessed every 10 years. As indicated on 

the map, the Great and Little Miami River Basins is part of the third set of intensive investigations, which began in 1997.

1991–95

1994–98

1997–2001

Not yet scheduled

HighPlains Regional

GroundWaterStudy,

1999–2004

NAWQA Study Units—

Assessment schedule

Great and Little Miami

River Basins

iv
What kind of water-quality information does the NAWQA 

Program provide?

Water-quality assessments by a single program cannot possibly address all of the Nation’s 

water-resources needs and issues. Therefore, it is necessary to define the context within which 

NAWQA information is most useful. 

• Total resource assessment—NAWQA assessments are long-term and interdisciplinary, 

and include information on water chemistry, hydrology, land use, stream habitat, and 

aquatic life. Assessments are not limited to a specific geographic area or water-resource 

problem at a specific time. Therefore, the findings describe the general health of the total 

water resource, as well as emerging water issues, thereby helping managers and decision 

makers to set priorities.

• Source-water characterization—Assessments focus on the quality of the available, 

untreated resource and thereby complement (rather than duplicate) Federal, State, and 

local programs that monitor drinking water. Findings are compared to drinking-water 

standards and health advisories as a way to characterize the resource.

• Compounds studied—Assessments focus on chemical compounds that have well-established methods of investigation. It is not financially or technically feasible to assess all 

the contaminants in our Nation’s waters. In general, the NAWQA Program investigates 

those pesticides, nutrients, volatile organic compounds, and metals that have been or are 

currently used commonly in agricultural and urban areas across the Nation. A complete 

list of compounds studied is on the NAWQA Web site at water.usgs.gov/nawqa.

• Detection versus risk—Compounds are measured at very low concentrations, often 10 

to 100 times lower than Federal or State standards and health advisories. Detection of 

compounds, therefore, does not necessarily translate to risks to human health or aquatic 

life. However, these analyses are useful for identifying and evaluating emerging issues, 

as well as for tracking contaminant levels over time.

• Multiple scales—Assessments are guided by a nationally consistent study design and 

uniform methods of sampling and analysis. Findings thereby pertain not only to water 

quality of a particular stream or aquifer, but also contribute to the larger picture of how 

and why water quality varies regionally and nationally. This consistent, multi-scale 

approach helps to determine if a water-quality issue is isolated or pervasive. It also 

allows direct comparisons of how human activities and natural processes affect water 

quality in the Nation’s diverse environmental settings. 

v
Introduction to this Report

This report contains the major findings of a 1999–2001 assessment of water quality in the Great 

and Little Miami River Basins. It is one of a series of reports by the National Water-Quality 

Assessment (NAWQA) Program that present major findings in 51 major river basins and aquifer systems across the Nation. 

In these reports, water quality is discussed in terms of local, State, and regional issues. Conditions in a particular basin or aquifer system are compared to conditions found elsewhere and 

to selected national benchmarks, such as those for drinking-water quality and the protection of 

aquatic organisms. 

This report is intended for individuals working with water-resource issues in Federal, State, or 

local agencies, universities, public interest groups, or in the private sector. The information will 

be useful in addressing a number of current issues, such as the effects of agricultural and urban 

land use on water quality, human health, drinking water, source-water protection, hypoxia and 

excessive growth of algae and plants, pesticide registration, and monitoring and sampling strategies. This report is also for individuals who wish to know more about the quality of streams 

and ground water in areas near where they live and how that water quality compares to the 

quality of water in other areas across the Nation.

The water-quality conditions in the Great and Little Miami River Basins summarized 

in this report are discussed in detail in other reports that can be accessed from (http://

oh.water.usgs.gov/miam/intro.html). Detailed technical information, data and analyses, collection and analytical methodology, models, graphs, and maps that support the findings presented 

in this report, in addition to reports in this series from other basins, can be accessed from the 

national NAWQA Web site (water.usgs.gov/nawqa). 

“Data from the NAWQA supplied critical information for 

Ohio EPA’s Total Maximum 

Daily Load (TMDL) effort in 

the Stillwater River Basin, and 

will continue to provide valuable data for future TMDLs in 

other subbasins of the Great 

Miami River. Additionally, 

the NAWQA study has helped 

further our understanding of 

linkages between nutrients, 

land use, and impairment of 

aquatic life. The USGS has 

also been particularly generous 

in sharing scientific expertise 

developed by NAWQA with 

Ohio EPA, especially their 

expertise in sampling algal 

communities.”

 Robert J. Miltner

 Aquatic Ecologist

 Ohio Environmental Protection Agency 

“In partnership with the 

NAWQA Program, we collected a significant amount 

of ground-water-quality data 

that neither agency could have 

obtained individually. The data 

provide an important snapshot 

of the overall health of ground 

water—the region’s primary 

source of drinking water. The 

information generated through 

this partnership will help our 

region formulate more effective ground-water management 

strategies in the future.” 

 Michael P. Ekberg

 Groundwater Program Manager

 Miami Conservancy District

“In southwest Ohio, the USGS 

NAWQA Program has tapped an 

extraordinary number of research 

sources to perform a water-quality 

assessment of the Great and Little 

Miami River Basins. NAWQA 

is developing a picture of water 

quality that did not previously 

exist. This is a service for many 

constituents who rely on the 

Basins’ water resources, including 

the dozens of public water 

suppliers who must produce safe 

drinking water and the towns and 

cities whose histories and futures 

are linked to the health of the 

rivers and the aquifer.”

Jane Wittke

Water Quality Program Planner

Ohio-Kentucky-Indiana Regional

 Council of Governments

vi
Summary of Major Findings 1

EXPLANATION

Urban

Agriculture

Forest

Water

DAYTON

SPRINGFIELD

RICHMOND

MIDDLETOWN

CINCINNATI

MILES

KILOMETERS

The Great and Little Miami River Basins drain about 7,354 square 

miles of southwestern Ohio and southeastern Indiana. More than 

2.8 million people reside in the basin, most in and around the 

Cincinnati and Dayton metropolitan areas. Land use outside the 

two metropolitan areas is dominated by production of corn and 

soybeans. Ground-water sources provide most domestic and 

public drinking-water supplies.

Stream and River Highlights

Since the early 1900s, streams in the Great and Little 

Miami River Basins have been affected by various human 

activities, including agriculture, urbanization, discharge of 

industrial and municipal waste, ditching and tiling of farmland, and channel modification for flood control. Cleanup of 

contaminants, especially those discharged directly into streams 

by point sources, began in earnest in the 1970s after passage 

of the Clean Water Act. Although stream quality has improved 

significantly since then, elevated concentrations of nutrients 

and pesticides were frequently detected in streams during 

1999–2001, sometimes at levels that exceeded guidelines set 

for the protection of human health or aquatic organisms. Persistent organic contaminants no longer used, such as polychlorinated biphenyls (PCBs) and organochlorine pesticides, are 

still present in streambed sediment and fish tissue at concentrations that exceed aquatic-life guidelines.

• At least one pesticide was detected in all streams, sometimes at concentrations at or above drinking-water standards or aquatic-life 

guidelines. (p. 5, 9–10)

• Two of the most heavily used herbicides, atrazine and metolachlor, 

were detected in 98 and 94 percent of the samples, respectively, 

whereas glyphosate, whose use on cropland is approaching that 

of atrazine, was detected less frequently. (p. 5, 7, 9)

• Insecticides commonly used by homeowners on lawns and gardens, 

such as diazinon and imidacloprid, were frequently detected in 

samples from a small urban stream, Holes Creek. Concentrations of diazinon exceeded guidelines for protecting aquatic life 

in 33 percent of the samples from Holes Creek. (p. 7, 10)

• Degradates (breakdown products) of acetochlor, alachlor, and metolachlor were detected throughout the year at concentrations 

higher than those of the parent compounds. Some degradates 

may have equal or greater toxicity and may persist longer in the 

environment than the parent compound. (p. 10–11)

• Although atrazine concentrations in untreated Harsha Lake water 

occasionally exceeded the U.S. Environmental Protection 

Agency (USEPA) drinking-water standard, atrazine concentrations in samples of treated drinking water were always within 

the standard, particularly after the water-treatment method was 

changed from powdered activated carbon to granular activated 

carbon. (p. 10)

• Streams draining agricultural land had the highest mean concentration of nitrogen, whereas streams draining a mix of land uses 

had the highest mean concentration of phosphorus. Commercial 

fertilizer and manure applications to agricultural lands are a 

major source of nitrogen to area streams. Numerous wastewater-treatment discharges at and downstream from Dayton 

are a primary source of phosphorus to mixed-land-use streams. 

(p. 20, 22)

• Phosphorus concentrations have decreased by about 50 percent 

in the Great Miami River and 40 percent in the Little Miami 

River since 1974. Mean annual concentrations of phosphorus, 

however, remained above the USEPA recommended guideline 

of 0.1 milligram per liter. (p. 22)

• Sixty-one of the 116 household chemicals and pharmaceuticals for 

which the samples were analyzed were detected at low concentrations in streams draining mixed-land use and urban land. In 

a separate study of 29 small streams that drain areas of various 

land uses, 46 of 58 household chemicals were detected at low 

concentrations. The number of chemicals detected increased 

with increasing amounts of urban land. (p. 13–15, 25–26)

• Polychlorinated biphenyls and organochlorine insecticides whose 

use was canceled or restricted in the 1970s and 1980s continue 

to persist in fish tissue; many such chemicals were detected at 

concentrations at or near the maximum concentrations found 

nationwide by the NAWQA Program. (p. 15, 17)

• Elevated concentrations of polycyclic aromatic hydrocarbons 

(PAHs) and other semivolatile organic compounds (SVOCs) 

are widespread in sediment (p. 15–17). The number of synthetic 

organic compounds (SOCs) detected in streambed sediment 

increased as the percentage of urban land increased. (p. 26)

• Excessive growth of algae was found in some large streams with 

elevated nutrients and relatively open tree canopy. Composition 

and condition of fish communities in nutrient- and algal-rich 

streams was variable. (p. 24)

• Stream-water quality declined as the percentage of urban land 

upstream from the sampling site increased. Increases in the 

number of household chemicals and pharmaceuticals, concentration of chloride, and total concentration of insecticides in 

stream water—plus the number of synthetic organic compounds 

detected in the streambed sediments contributed to the decline. 

(p. 25–28)

Summary of Major Findings
• The structure of biological communities in streams ranging from 

minimally to highly urbanized reflects a complex combination of water and sediment quality and stream habitat. Certain 

chemical characteristics, such as elevated trace metals in sediment and pesticides and other organic compounds in water, are 

associated with decreases in relative abundance and diversity of 

fish, invertebrates, and algae in some urban streams. (p. 25–28)

Ground-Water Highlights 

Most residents and many industries in the Great and 

Little Miami River Basins rely on water pumped from the 

buried-valley aquifer system, and this demand for ground 

water is increasing as people move to suburban and rural 

areas. With few exceptions, ground-water quality is suitable 

for drinking and other domestic uses. Water from shallow 

wells (less than 50 feet deep) is vulnerable to contamination 

by chemicals applied or spilled on the land; hence, shallowwater quality tends to reflect overlying land use and human 

activities. Water from deeper public-supply wells (median 

depth 78 feet), also can be vulnerable to contamination 

because of induced infiltration of stream water, which can 

reach wells within weeks or even days. Water from domestic 

wells (median depth 60 feet) in areas not affected by induced 

infiltration or heavy pumping is, in general, the least vulnerable to contamination.

• One or more pesticides were detected in 63 percent of 96 samples, 

but no concentrations exceeded drinking-water standards or 

guidelines. Herbicide degradates (breakdown products) were 

the most frequently detected class of pesticides. (p. 11–12)

• Pesticides were detected most frequently and at the highest total 

concentrations in water pumped from public-supply wells near 

streams, compared to concentrations in water from domestic 

wells or shallow monitoring wells in agricultural and urban 

areas. (p. 12)

• Nitrate concentrations in 10 of 104 samples exceeded the USEPA 

drinking-water standard of 10 milligrams per liter. Concentrations of nitrate in water from shallow monitoring wells in agricultural areas were the highest among area wells and among 

the highest in the Nation. (p. 19)

• Five of 104 samples exceeded the USEPA drinking-water standard 

of 10 micrograms per liter for arsenic, which was revised in 

2002 (p. 16, 19). Radon concentrations were greater than 300 

picocuries per liter, the proposed USEPA drinking-water standard, in 70 percent of the samples. (p. 18)

• Twenty volatile organic compounds were detected in ground water 

collected from public-supply, domestic, and shallow urban 

monitoring wells installed in urban areas. No USEPA drinkingwater standards or guidelines were exceeded. (p. 13)

• Of the 116 household chemicals and pharmaceuticals for which the 

samples were analyzed, 16 were detected at very low concentrations in shallow ground water from 19 of 25 monitoring 

wells in urban areas developed after 1960. (p. 13–15)

Selected Indicators of Ground-Water Quality

Nitrate

Arsenic

Herbicides

Insecticides

Radon

Volatile

organics1

—

Proportion of samples with detected concentrations

greater than or equal to health-related national

guidelines for drinking water

Proportion of samples with detected concentrations less

than health-related national guidelines for drinking

water

Proportion of samples with no detections

Not assessed

1 Solvents, refrigerants, fumigants, and gasoline compounds.

Shallow Ground Water Supply Wells

Urban Agricultural Domestic Public

—

 

 

Major Influences on Ground Water

 • Geologic and hydrologic factors (type of aquifer material, 

 depth to water, rate of recharge)

 • Agricultural and urban land use around well

 • Induced infiltration of stream water to public-supply wells

Major Influences on Streams and Rivers

 • Runoff from agricultural and urban areas

 • Discharges from wastewater-treatment facilities

 • Contamination of fish tissue and sediment by persistent 

 organic chemicals 

Small Streams Major Rivers

Agricultural Urban

Selected Indicators of Stream-Water Quality

Mixed

Land Uses

Nitrate

Total

phosphorus

Herbicides

Insecticides

Organo- chlorines in tissue1

Organo- chlorines in sediment1

Proportion of samples with detected concentrations

greater than or equal to health-related national

guidelines for drinking water, protection of aquatic life, or

the desired goal for preventing nuisance plant growth

Proportion of samples with detected concentrations less

than health-related national guidelines for drinking

water, protection of aquatic life, or below the desired

goal for preventing nuisance plant growth

Proportion of samples with no detections

1 DDT and PCB's.

2 Water Quality in the Great and Little Miami River Basins
Introduction 3

Introduction to the Great and Little Miami River Basins

Note: Terms in bold are defined in 

the glossary

Since the 1970s, water quality 

in the Great and Little Miami River 

Basins (hereinafter, “Study Unit”) has 

improved significantly, mainly because 

of improvements in the treatment of 

wastewater. As point-source pollution has decreased, particularly in 

larger streams, attention has shifted 

to nonpoint sources and the effects 

of land use on water quality. Today, 

water-resource managers and suppliers 

are interested in the effects of nonpointsource pollution on contaminant loads 

in streams, health of aquatic organisms, 

and degradation of streams and aquifers used for water supply.

Past glacial activity influences quality and quantity of 

water today

Advancing glaciers leveled 

underlying limestone and shale bedrock and covered most of the Study 

Unit with thick deposits of till—a 

mix of clay, silt, sand and gravel 

(fig. 1). The flat to gently rolling 

landscape is ideal for agriculture. 

Soils formed from till tend to be fertile but have a high clay content and 

drain poorly. Clay-rich soils protect 

underlying ground water by inhibiting downward movement, but they 

allow sediment and applied chemicals to run off into streams during 

rainstorms. Near the Ohio River, 

glacial deposits are thin or absent, 

and erosion of less resistant shale 

has produced a more dissected, 

hilly terrain that is less suitable for 

farming. 

Retreating glaciers filled 

bedrock valleys with outwash

deposits of sand and gravel as thick 

as 250 feet. Such deposits form 

the buried-valley aquifer system, 

a major source of drinking water. 

Depth to water is 20 feet or less in 

most locations. Soils derived from 

glacial outwash tend to be well 

drained, making ground water vulnerable to contamination. In areas 

with extensive outwash deposits of 

sand and gravel (fig. 1), discharge 

of ground water to streams can 

make up most of the streamflow, 

particularly during dry summer 

months and droughts. During dry 

periods, ground water discharged 

to streams also can dilute wastewater from point sources. Conversely, 

contaminants may be added to the 

stream at locations where contaminated ground water discharges. 

Land use affects water 

quality and aquatic 

organisms

Despite increased urban 

development, agriculture remains 

the dominant land use, covering 

about 78 percent of the Study Unit 

(fig. 2). Corn and soybeans are 

grown on approximately 2.5 

million acres of cropland that 

surround the heavily urbanized 

Dayton-Cincinnati corridor. 

Fertilizer, manure, and pesticides are applied to cropland 

to increase production but in 

excess can run off from fields 

during storms, resulting in high 

concentrations of nutrients

and pesticides in streams. The 

practice of ditching, tiling, 

and channel straightening to 

improve drainage causes degradation of stream habitat and 

leads to a reduction in the number of sensitive aquatic organisms. Confined animal feeding 

operations (CAFOs), mainly for 

poultry and swine, are concentrated in the northwestern part 

of the Study Unit, mostly in the 

Stillwater River Basin. Over 

the past few decades, animal 

production in this basin has 

paralleled the national trend of 

fewer, larger farms producing 

more animals. 

EXPLANATION

Sand and gravel

Clay and silt

Till

Patchy sediments

with exposed bedrock

Exposed bedrock

MILES

KILOMETERS

40o 40o

39o

84o

84o

85o

85o

0 10 20 30

0 10 20 30

MILES

KILOMETERS

EXPLANATION

LAND USE

Urban land developed

between 1970 and 2000 (3.7%)

Urban land in 1970 (10.7%)

Other land use in 2000 (7.1%)

Agricultural land in 2000 (77.8%)

Water (0.7%)

39o

Figure 1. Sand-and-gravel deposits—an 

important source of drinking water—also 

discharge large volumes of ground water to 

the Mad and Whitewater Rivers. 

Figure 2. Recent urban development is 

concentrated around the margins of large 

cities and towns.
4 Water Quality in the Great and Little Miami River Basins

Drier than normal weather 

affected study findings

Water quality in streams and shallow ground water varies in response 

to hydrologic conditions, so information on precipitation, streamflow, and 

ground-water levels is critical for 

assessing water-quality conditions. 

Streamflow generally fell below the 

30-year average during the first 2 years 

of sampling as a result of moderate to 

severe drought throughout the Study 

Unit (fig. 5). Many small streams 

draining areas underlain by thin glacial 

deposits or shale bedrock in the southern part of the Study Unit stopped 

flowing in 1999. 

During dry periods when streamflow is low, water quality is affected 

primarily by discharge of municipal 

and industrial wastewater, so aquatic 

organisms may be exposed to higher 

concentrations of wastewater compounds (such as nutrients) than during 

periods of normal or high streamflow 

and may also be affected by algal 

blooms that reduce dissolved-oxygen 

concentrations. In wet periods, streamwater quality is affected by urban 

and agricultural runoff, and aquatic 

organisms may be temporarily exposed 

to chemicals spilled, deposited, or 

recently applied to the land surface.

Ground-water levels in the buried-valley aquifer system also were 

affected by the drought, but the effects 

of changing ground-water levels on 

water quality are difficult to predict. 

Below-normal rainfall caused water 

levels in some parts of the buried-valley aquifer to decline before sampling 

began in May 1999. Water levels 

remained below the 30-year average 

for most of 2000 and 2001 (fig. 5). 

Figure 3. Population trends in Dayton and 

Cincinnati indicate migration of city residents 

to less densely populated parts of the Study 

Unit. 

Figure 5. Stream-water samples were collected over a range of flows despite widespread drought in 1999 and 2000. Groundwater samples often were collected when 

rainfall and ground-water levels were below 

average. (Average and percentiles based on 

1971 through 2000 data.)

For a detailed description of the natural and human factors affecting water 

quality in the Great and Little Miami 

River Basins Study Unit, refer to the 

report by Debrewer and others (2000). 

The report can be downloaded at 

http://in.water.usgs.gov/newreports/

miami/miami.pdf 

Additional Information

Figure 4. Public supply accounts for 40 

percent of the water used in the Study Unit.

Land used for residential, commercial, and industrial activities covered 

about 14 percent of the Study Unit 

in 2000. Since 1970, more than 270 

square miles have been converted from 

farmland and forest to low-density residential and commercial areas (fig. 2). 

Census data show declining populations 

in Cincinnati and Dayton, suggesting 

relocation of city dwellers to surrounding suburban and rural areas (fig. 3). 

Conversion of farmland and forest to 

residential and commercial land can 

lead to an increase in the amount of 

runoff, sediment, and wastewater discharged to streams and also can affect 

aquatic organisms, especially sensitive 

species, by degrading water quality and 

physical habitat. 

Public water supplies depend

on ground water

In 2000, approximately 1 billion 

gallons of water per day was used in 

the Study Unit; about 60 percent from 

surface water and about 40 percent from 

ground water (fig. 4). About two-thirds 

of the surface water is used for power 

generation. Although many people in 

Cincinnati obtain drinking water from 

the Ohio River, most residents and 

industries in the Study Unit rely on 

water pumped from the buried-valley 

aquifer system for drinking water. In the 

northern part of the Study Unit, where 

sand- and-gravel deposits are absent, 

minor amounts of drinking water are 

pumped from sand-and-gravel lenses 

in till and from underlying carbonate 

bedrock.

Water managers are concerned 

about water-quantity issues associated with urban development along the 

Miami Valley. Growing towns and cities 

in upland areas are placing increased 

demands on well fields that pump water 

from the buried-valley aquifer in adjacent stream valleys. Many public-supply 

wells are drilled near streams and rely 

on induced infiltration of stream water 

to sustain high pumping rates. Some 

contaminants in stream water that are 

not removed by natural filtration through 

aquifer sediments, however, may be 

transported to wells. 
Major Findings 5

Major Findings

Pesticides

Pesticides (herbicides, insecticides, 

and fungicides) are used extensively 

in agricultural and urban settings in the 

Study Unit for control of weeds, insects, 

and fungi. Pesticide use varies by land 

use. In agricultural areas of the Study 

Unit, herbicides are applied to virtually 

all corn and soybean fields, whereas 

insecticides are used mostly to spot treat 

infestations in corn (fig. 6). 

Trends in agricultural pesticide use 

in the Study Unit changed substantially 

starting in the early 1990s (fig. 7). Such 

changes include the following: 

• Conditional registration by U.S. Envi-

 ronmental Protection Agency (USEPA)

 in 1994 of the herbicide acetochlor to

 replace alachlor use on corn

• Increased use of the herbicide glypho-

 sate (RoundupTM, RodeoTM, AccordTM)

 in response to introduction of glypho-

 sate-resistant soybeans in 1995 (see 

 p. 9)

• Registration of a more effective form

 of the herbicide metolachlor (S-meto-

 lachlor) in 1999 which, along with 

 the increased use of acetochlor, caused

 sharp reductions in metolachlor use in 

 Ohio and Indiana (fig. 7). 

 Atrazine is the most commonly 

applied herbicide on cropland, in applications of more than 1.1 million pounds per 

year (table 1). Estimates of pesticide use 

in urban areas of the Study Unit were not 

available, but national rankings indicate 

that 2,4-D is the most commonly applied

herbicide to urban areas. Pesticides are 

commonly used for weed and insect 

control on lawns, golf courses, road 

rights-of-way, and home and building 

perimeters in urban areas.

Pesticides in Streams

The transport of a pesticide from 

the site of application depends on the 

chemical stability of the pesticide, its 

solubility in water, and its tendency to 

adsorb to soil particles. Transport by 

water is the primary way most pesticides 

get into water supplies—by seeping into 

ground water and running off to streams. 

Spray drift and atmospheric transport by 

volatilization of pesticides are additional 

ways pesticides can get into our water 

supplies.

Pesticides were detected in 

every stream sample

One or more pesticides were 

detected in each of the 184 samples 

collected from five stream sites from 

March 1999 through September 2001. 

Fifty-eight pesticides were detected in 

stream water: 37 herbicides, 10 herbicide 

degradates, 9 insecticides, and 2 fungicides. Most samples contained mixtures 

of 10 to 20 pesticides. Samples collected 

during runoff events from the East Fork 

Little Miami River and the Great Miami 

River contained mixtures of 31 pesticides.

Heavily used herbicides 

in agricultural areas were 

detected in streams

Herbicides applied to cropland were 

frequently detected in streams draining 

all three of the major land-use settings 

(agriculture, Mad River; urban, Holes 

Creek; mixed, Great Miami River). (See 

Box 1.) The frequency of detection and 

the concentrations of herbicides, however, typically were lower in samples 

Study unit ranking of pesticides applied to

agricultural areas

Rank Pesticide

Application, in

1,000 pounds

1 * Atrazine

2 * Metolachlor

3 * Cyanazine

4 * Glyphosate

5 * Acetochlor

6 * 2,4-D

7 * Pendimethalin

8 * Alachlor

9 * Chlorpyrifos

10 * Simazine

National ranking of pesticides applied to urban

areas

Rank

Home and

garden use

Industrial and

commercial use

1 * 2,4-D * 2,4-D

2 * Glyphosate * Glyphosate

3 MCPP Copper sulfate

4 * Dicamba * Pendimethalin

5 * Diazinon * Chlorpyrifos

6 * Chlorpyrifos MSMA

7 * Carbaryl * Chlorothalanil

8 * Benfluralin * Diuron

9 * Malathion * Malathion

10 * Dacthal * Triclopyr

Fungicide Herbicide Insecticide

Pesticides applied to urban areas are based on 199899

proprietary sales data (Donaldson and others, 2002).

Pesticides applied to agricultural areas are based on

1997 estimates (Gail Thelin, U.S. Geological Survey,

written commun., 2001) [2,4-D, 2,4-dichlorophenoxyacetic acid;

MCPP, 2-(2-methyl-4-chlorophenoxy) propionic acid; MSMA,

monosodium methylarsonate]

1,120

944

476

410

337

161

150

109

106

99

* Pesticides analyzed in this study.

These findings are supported by the 

Study Unit Design presented on pages 

29 and 30 of this report. 

Additional Information

Table 1. Atrazine is the most commonly 

used pesticide in agricultural areas of the 

Study Unit. Pesticide use differs with land 

use in urban areas across the Nation.

Figure 7. Recent trends in agricultural 

pesticide use in Ohio and Indiana indicate 

that atrazine and glyphosate were the most 

abundantly applied herbicides in the Study 

Unit during 1999-2001. (Data from U.S. Department of Agriculture, 1991–2002.)

Figure 6. Herbicides are applied to 

cropland before and after spring plant- ing, mainly from mid-April through June.
6 Water Quality in the Great and Little Miami River Basins

Pesticide occurrence in streams varied in response to groundwater contributions; pesticides in ground water were generally 

comparable to those in the rest of the Nation and Corn Belt region 

Streams

The median concentration of summed 

herbicides found in the Great Miami River 

at Hamilton, 0.33 μg/L (microgram per 

liter), was similar to the median concentration for 13 mixed-land-use streams 

sampled in the Corn Belt Region by the 

NAWQA Program from 1991 to 2001 

but higher than the median concentration 

for 47 mixed land-use streams sampled 

nationwide by the NAWQA Program. The 

median concentration of summed herbicides in Holes Creek (0.12 μg/L), which 

drains urban lands, was only slightly higher 

than values for 4 urban streams sampled 

in the Corn Belt and the 33 urban streams 

sampled nationally by NAWQA. The median concentration of summed herbicides was lower for the Mad River (0.08 μg/L), which drains agricultural land and was lower than the median value for 25 agricultural streams sampled in the Corn Belt and 77 streams sampled nationwide by 

the NAWQA Program. The relatively low concentrations in the Mad River probably are a consequence of the large amounts of ground water 

discharged to the stream from sand-and-gravel deposits throughout the Mad River Basin (fig. 1). The lower pesticide concentrations in ground 

water chemically dilutes the stream water.

A small number of samples were collected from streams that drain agricultural land in areas of clayey and silty till (Stillwater and East 

Fork Little Miami Rivers). These streams receive minimal contributions from ground water and are fed by storm runoff and flow from ditches 

and tile drains. The median concentration of herbicides in the samples collected from these streams (0.98 μg/L) was about twice that measured in other agricultural streams sampled for NAWQA studies in the Corn Belt (0.44 μg/L) and about four times that for all agricultural 

streams s 

Unit, Corn Belt, and nationwide. Insecticides were not detected in agricultural streams in these three areas.

Ground water

The median detection frequencies of herbicides and insecticides in ground-water samples collected in the Study Unit were similar 

to those found by NAWQA studies in the Corn Belt Region and slightly lower than those found nationwide. One or more herbicides were 

detected in about 50 percent of samples from NAWQA monitoring wells 

installed in agricultural areas in the 

Study Unit, the Corn Belt, and nationwide, but herbicides were detected in 

25 percent or less of NAWQA samples 

from domestic wells. 

Insecticides were detected most 

frequently (in about 10 percent of 

samples) in NAWQA monitoring 

wells installed in urban areas in the 

Corn Belt and nationwide. None of 

the insecticides ranked in the top 10 

pesticides used in agricultural areas 

or urban areas (table 1), however, were 

detected in any of the 96 ground-water 

samples collected in the Study Unit.

Pesticide concentrations in streams were among the highest nationwide, but 

ground-water contributions lowered pesticide concentrations in the Mad River.

In ground water, herbicides were detected more frequently in samples from agricultural wells than in samples from urban and domestic wells.
Major Findings 7

collected from the Mad River than from 

the urban and mixed-land-use streams. 

Because of low concentrations of pesticides in ground water and extensive 

sand-and-gravel deposits that discharge 

large quantities of ground water to the 

Mad River (fig. 1), the stream water is 

chemically diluted. 

Atrazine and metolachlor, the two 

most commonly used herbicides in the 

Study Unit, were detected in 98 percent 

and 94 percent of samples, respectively. 

Some herbicides used for weed control 

in both agricultural and urban settings—

including 2,4-D, clopyralid, diuron, 

dicamba, MCPA, pendimethalin, siduron, 

and triclopyr—were detected more frequently in the urban and mixed-land-use 

streams than in the agricultural stream. 

Prometon, a nonagricultural herbicide 

used exclusively for vegetation control in 

rights-of-way, was detected in 97 percent 

of samples from the urban and mixedland-use streams. Relative to its use, 

glyphosate was detected less frequently 

than other high-use herbicides. (See p. 9.)

Insecticides and fungicides 

were detected more frequently 

in streams receiving runoff from 

urban areas than from agricultural areas

Diazinon was detected in 90 percent 

or more of the samples from the urban 

and mixed-land-use streams (fig. 8) but 

in less than 30 percent of the samples 

from the agricultural stream (Mad River). 

The maximum concentration of diazinon in the urban stream (Holes Creek) 

was 0.56 μg/L, whereas the maximum 

in the three agricultural streams (Mad 

River, Stillwater River, and East Fork 

Little Miami River) was 0.14, 0.013, and 

0.004 μg/L, respectively. Imidacloprid, an 

insecticide present in turfgrass products 

used to control grubs, was detected in 70 

percent of the samples collected from the 

urban stream, with a maximum concentration of 0.89 μg/L, but was not found 

in any samples from the agricultural or 

mixed-land-use streams. The fungicides 

benomyl and metalaxyl were detected 

 Box 2—Endocrine-disrupting compounds

Endocrine systems in animals release hormones that regulate body functions such as 

growth, embryonic development, and reproduction. Endocrine disruptors are organic 

chemicals that interfere with or mimic natural hormones and have the potential to cause 

reproductive or developmental impairment in animals (Smith, 1998). Chemicals believed to 

be endocrine disruptors include certain pesticides and pesticide degradates, various household chemicals, pharmaceuticals, and wastewater chemicals from industrial and municipal 

sources. Some chemicals known or suspected to be endocrine disruptors were detected in 

water, bed sediment, and fish-tissue samples collected in the Study Unit; these include the 

pesticides atrazine and diazinon and the household chemicals triclosan (found in antibacterial 

products) and benzophenone (a perfume and soap additive) (Environment Canada, 2002; 

Zaugg and others, 2002).

Figure 8. Pesticides found in study-unit streams were related to upstream land 

use. Overall, atrazine, metolachlor, prometon, and 2,4-D were the most frequently 

detected herbicides. Diazinon and metalaxyl were the most frequently detected 

insecticide and fungicide, respectively.

NAWQA reports detection frequencies to 

describe the occurrence of chemicals in 

water. All reported detections are used in 

comparisons of detections for a single chemical between different streams or groundwater networks. Because analytical method 

sensitivities vary widely from one chemical to 

another, however, a common reporting level 

(0.05 μg/L) is sometimes used to establish 

an equal basis for comparing detection 

frequencies for multiple chemicals at a single 

site or network.

 Box 1—Detection frequencies
8 Water Quality in the Great and Little Miami River Basins

in slightly more than one-half the 

samples collected from the urban 

stream, with maximum concentrations of 0.52 μg/L for benomyl and 

1.1 μg/L for metalaxyl.

Herbicide concentrations and loads varied in 

response to rainfall and 

runoff

Seasonal patterns in water 

quality emerged in agricultural 

basins, mainly reflecting the timing and amount of herbicide use 

and the frequency and magnitude 

of runoff from rainstorms and irrigation. 

Concentrations and loads of herbicides 

are highest during runoff following 

chemical applications. For example, 

monthly loads of atrazine computed 

for Mad River (agricultural) and Great 

Miami River at Hamilton (mixed land 

use) show this seasonal pattern during 

the 3-year monitoring period (fig. 9), 

when peak loads in the Great Miami and 

Mad Rivers (about 1,500 pounds and 

150 pounds) occurred in May 2001. 

Lower streamflows in the Study Unit 

during the drought produced the lowest 

atrazine loads in both rivers in autumn 

of 1999 (fig. 9). 

An understanding of seasonal 

variations in streamflow and pattens in 

pesticide use is important because they 

can significantly affect the timing of the 

highest concentration in aquatic habitats 

(possibly affecting, for example, critical 

life stages of aquatic organisms) and 

drinking-water supplies. For example, 

seasonal patterns typically occur in Harsha Lake, an important drinking-watersupply reservoir in the southeastern part 

of the Study Unit that is fed primarily 

by the agriculture-draining East Fork 

Little Miami River. The maximum 

concentration of atrazine in the East Fork 

Little Miami River at Williamsburg in 

1999 (7 μg/L) was about one-third the 

maximum concentration in 2000 (about 

20 μg/L) (fig. 10). Probably because 

of the drought, the increase in atrazine 

concentrations that typically follows the 

“spring flush” of pesticides applied during the planting season did not occur in 

Harsha Lake in 1999 (Funk and others, 

2003). Instead, atrazine concentrations in 

Figure 9. Atrazine loads in streams varied in 

response to runoff events and application periods 

and were lowest during the 1999 drought, but 

seasonally were highest in April and May. Figure 10. Atrazine concentrations in 

Harsha Lake (reservoir intake) were low 

and varied little during the 1999 drought, 

but they increased sharply and remained 

high during summer 2000.

Various Federal, State, and Canadian 

standards, guidelines, criteria, and waterquality goals have been selected for use 

by the NAWQA Program as benchmarks 

to compare chemical concentrations in 

water, sediment, and fish tissue on a 

national basis. Many benchmarks consist 

of nonenforceable guidelines designed to 

protect the health of humans and aquatic 

organisms. Other benchmarks are used 

in the regulation of the quality of drinking 

water and are applicable only to treated 

drinking water, not the untreated water 

samples the USGS collects from streams 

and wells. References in this report to any 

chemical in “exceedance” of a benchmark 

concentration are for comparison only and 

do not imply regulatory violations. 

The USEPA is responsible for setting 

drinking-water standards to protect human 

health. A Maximum Contaminant Level 

(MCL), commonly referred to as a primary 

drinking-water standard, is the maximum 

allowable concentration of a contaminant 

in water delivered to any public-watersystem user. MCLs are legally enforceable standards for treated drinking water. 

A Secondary Maximum Contaminant Level 

(SMCL), commonly referred to as a secondary 

drinking-water standard, is a nonenforceable 

guideline for the concentration of a contaminant that may cause undesirable cosmetic 

effects (such as skin or tooth discoloration) 

or aesthetic effects (such as taste, odor, or 

color) in drinking water. A Health Advisory 

Level (HAL) is also a nonenforceable, riskbased guideline. HALs indicate contaminant 

exposures below which no short- or long-term 

human-health effects are expected, based on 

drinking a specific amount of water for a specific period of time. Risk of illness increases 

with exposure time and concentration. Of 117 

pesticides and degradates for which water 

samples were analyzed for this study, 13 have 

MCLs and 27 have HALs. 

Guidelines to protect aquatic life have been 

set by several agencies, including the USEPA, 

Environment Canada, and the International 

Joint Commission (IJC). The aquatic-life guidelines for water developed by USEPA are based 

on 4-day average concentrations, are intended 

to protect 95 percent of the aquatic species, 

and should not be exceeded more than once 

in 3 years. The Canadian and IJC aquatic-life 

guidelines, which are more stringent than 

those of the USEPA, indicate a single 

maximum concentration that should never 

be exceeded. Aquatic-life guidelines for 

water have been established for only 32 of 

the 117 pesticides included in this study.

Currently, the United States does not 

have sediment-quality criteria to protect 

benthic organisms. Canadian Interim 

Sediment Quality Guidelines were used to 

evaluate freshwater sediment quality for 

semivolatile organic compounds and 

trace elements. These sediment-quality 

guidelines (SQGs) consist of two effect 

values, the Threshold Effect Level (TEL) 

and Probable Effect Level (PEL). The TEL 

defines the contaminant concentration in 

bed sediment below which adverse biological effects rarely occur, whereas PEL is the 

contaminant concentration above which 

adverse biological effects frequently occur. 

PELs have been established for 22 of the 

97 organochlorine insecticides and 

semivolatile organic compounds and 7 of 

45 trace elements analyzed for this study.

Box 3—What benchmarks are used for assessing water quality in this report?
Major Findings 9

Harsha Lake remained relatively constant in 1999 and 

early 2000 until heavier rainfall and runoff in the spring 

of 2000 transported large quantities of the herbicide 

into the reservoir. Four of the five untreated reservoir 

samples collected after June 2000 had atrazine concentrations exceeding the USEPA drinking-water standard 

of 3 μg/L, but atrazine concentrations in samples collected from the treatment plant were well within this 

drinking-water standard. (See page 10.)

Aquatic-life guidelines for pesticides were 

exceeded in 27 percent of stream samples

Concentrations of pesticides in excess of aquaticlife guidelines were not uncommon in study-unit 

streams. Pesticides present at concentrations that 

exceeded aquatic-life guidelines in one or more stream 

samples included the herbicides atrazine, cyanazine, 

metribuzin, and metolachlor and the insecticides carbaryl, chlorpyrifos, diazinon, and malathion.

Overall, pesticide concentrations exceeded 

aquatic-life guidelines in 27 percent of stream samples, 

but land use, streamflow, and pesticide-application 

periods were important in determining when, where, 

and what pesticides exceeded guidelines. Aquaticlife guidelines for herbicides were most frequently 

exceeded in streams draining agricultural land, whereas 

aquatic-life guidelines for insecticides were most 

frequently exceeded in the urban stream, Holes Creek 

(fig. 11). One or more aquatic-life guidelines were exceeded in 17 

percent of samples from streams sampled multiple times over a range of 

streamflow conditions and land use. In contrast, one or more guidelines 

were exceeded in 100 percent of spring-runoff samples from streams 

draining cropland following the application of pesticides. Atrazine 

concentrations in all of these spring-runoff samples exceeded the 

aquatic-life guideline of 1.8 μg/L. Of the samples collected in summer 

2001, no herbicide concentrations exceeded aquatic-life guidelines; the 

percentage of samples that exceeded one or more aquatic-life guidelines 

Figure 11. Aquatic-life guidelines for insecticides were exceeded 

most often in Holes Creek, an urban stream, whereas guidelines for 

herbicides were exceeded most often in agricultural streams during 

spring runoff.

Glyphosate is a broad-spectrum, nonselective, post-emergent herbicide. It 

strongly adsorbs onto soil and degrades 

relatively quickly; moreover, it is believed 

to be relatively nontoxic to most terrestrial and aquatic organisms (Giesy and 

others, 2000). Following introduction of 

genetically modified soybeans in 1995, 

the acreage planted with glyphosate-tolerant soybeans increased rapidly, and by 

2001, accounted for more than 70 percent 

of the total soybean acreage in Ohio and 

Indiana (U.S. Department of Agriculture, 

1991–2002). Farmers have switched to 

glyphosate-tolerant soybeans because 

use of a single herbicide simplifies weed 

control and lowers costs. As a result, the 

amount of glyphosate applied to cropland 

is quickly approaching that of atrazine, the 

most heavily used herbicide in the Study 

Unit (fig. 7) and the rest of the Corn Belt. 

In addition to increased agricultural use, 

glyphosate is commonly used in urban 

areas for weed control on lawns and turf, 

building perimeters, and rights-of-way 

(table 1).

Glyphosate was detected infrequently in 

agricultural and mixed-land-use streams at 

concentrations above 1.0 μg/L and was not 

detected at this level in small urban streams. 

Concentrations of glyphosate greater than 

1.0 μg/L were detected at about the same 

frequency in samples of agricultural runoff 

collected from 30 small subbasins in the rural Stillwater 

River Basin after a large 

spring storm and in samples 

collected from 30 small subbasins (less than 75 square 

miles) in areas with varying 

amounts of urban and 

agricultural land in the Dayton-Cincinnati region during 

a summer low-flow period. 

The maximum concentrations of glyphosate for 

the two groups of samples 

were 3.6 and 9.2 μg/L, 

respectively, well below 

the current drinking-water 

standard of 700 μg/L and 

the aquatic-life guideline of 

65 μg/L.

Glyphosate was not 

detected in shallow ground 

water beneath cropland or 

in four sets of tile drains sampled before, 

during, and after the 2001 growing season. 

Glyphosate is unlikely to be found in 

ground water because of its strong tendency 

to adsorb to soil and biodegrade.

Glyphosate was detected infrequently in streams and not found in ground water 

Glyphosate was detected less frequently than atrazine 

in streams draining agricultural and mixed-land-use 

basins. Although both herbicides are used in large 

quantities, atrazine is more resistant to degradation 

than glyphosate and is less likely to bind to soil. 
10 Water Quality in the Great and Little Miami River Basins

the oxanilic acid (OA) and ethane-sulfonic acid (ESA) 

degradates of these herbicides were typically more than 

10 times the concentrations of the parent chemicals. 

Alachlor and acetochlor were detected in streams during 

the spring application periods but were mostly absent 

from streams during the remainder of the year. Metolachlor, atrazine, and atrazine degradates were detected in 

streams throughout the year; the summed concentration 

for insecticides, however, was similar to that for Holes Creek. There, 

concentrations of the insecticide diazinon exceeded the aquatic-life 

guideline of 0.08 μg/L in 33 percent of the samples collected over a 

2.5-year period. Most samples with high concentrations of diazinon 

were collected from June through September, when many homeowners 

apply insecticides.

Potential toxicity of pesticide mixtures varied by season 

and land use

Aquatic-life guidelines, which are developed for individual pesticides, do not account either for the continuous exposure of fish and 

benthic organisms to mixtures of pesticides or for seasonal variations in 

concentrations. Little is known about the possible concurrent or cumulative effects on aquatic life from multiple pesticides at low concentrations, or effects of lengthy periods of low concentrations punctuated by 

brief seasonal pulses of much higher concentrations. The Pesticide Toxicity Index (PTI) combines pesticide exposure of aquatic organisms with 

toxicity estimates and is used to rank or compare the relative toxicity of 

samples or sites (Munn and Gilliom, 2001). High PTI scores are associated with higher toxicities, and in general, insecticides are more toxic 

than herbicides to benthic invertebrates and fish. Samples from Holes 

Creek (urban), in which numerous insecticides were detected, almost 

always had a higher PTI score for benthic invertebrates than samples 

from Mad River (agricultural) (fig. 12). PTI scores also were shown to 

increase with increasing percentage of urban land in basins. (See p. 28.) 

The Mad River occasionally had PTI scores similar to those for Holes 

Creek, but only when pesticides were applied to agricultural areas in 

the spring and summer. When agricultural streams within the Stillwater 

River Basin were sampled during spring runoff, however, PTI scores for 

those streams were significantly higher than those for Holes Creek

(fig. 12). (See Box 4.)

Pesticide degradates were detected more often than 

many parent chemicals

Degradates of acetochlor, alachlor, and metolachlor were detected 

in stream samples throughout the year. The summed concentrations of 

Figure 12. Pesticide Toxicity Index scores for the 

urban Holes Creek were higher than those for the 

agricultural Mad River, but the scores for Mad River did 

approach scores for Holes Creek in spring and summer.

In 1999, USEPA and USGS initiated a 2-year assessment of pesticide concentrations in drinking water. In support of USEPA’s responsibility under the Food Quality Protection Act of 1996, the program was designed as a first step toward a long-term goal of characterizing 

human exposure to pesticide residues in drinking water derived from 

surface-water sources. Harsha Lake, which drains primarily agricultural 

land and supplies drinking water to about 40,000 residents of Clermont 

County, Ohio, was one of 12 reservoirs sampled in the national assessment of 186 pesticides and degradation products. From March 1999 

to September 2000, 21 samples each of untreated and treated water 

were collected. Drinking-water standards or advisory levels have been 

established for 19 of the 37 pesticides detected. Analysis of the samples 

indicate that atrazine concentrations in treated water were always below 

the drinking-water standard and suggest that the practices employed at 

the Harsha Lake Water Treatment Plant (activated carbon, oxidation, 

chlorination) were effective in reducing pesticide concentrations (Funk 

and others, 2003). Atrazine concentrations in samples of treated water 

were well below the atrazine drinking-water standard of 3 μg/L, even 

in samples collected after June 2000 when atrazine concentrations in 

untreated water from Harsha Lake were consistently at or above the 

drinking-water standard. 

Box 4—Use of the term “Significant”

In discussions of statistical analyses, the term “significant” 

means the analysts believe that the apparent relation has 

a specific probability of being real and not due to chance. 

In this report, the selected level of significance is less than 

5 percent (p < 0.05). Nonparametric statistics were used to 

evaluate the water-quality datasets because the datasets 

are small and not normally distributed.

Atrazine concentrations in treated water from Harsha Lake met drinking-water standard

Atrazine concentrations were lowered in treated water when

granular activated carbon was used in water treatment.
Major Findings 11

of atrazine degradates, however, was 

similar to the concentration of the parent chemical (fig. 13). Little is known 

about the possible effects of degradates 

on human health and aquatic life. (See 

Box 5.)

Pesticides in Ground Water

Pesticides and other chemicals that 

dissolve in water can seep into ground 

water. Shallow wells (less than 50 feet 

deep) are most vulnerable to contamination by these chemicals, which can 

move from land surface to the water 

table in a few months to a few years. 

Deeper domestic wells (median depth 

of 60 feet) are generally less vulnerable to contamination, and recharge

water may take several years to decades 

to reach deeper wells or parts of the 

aquifer. In contrast, public-supply wells 

(median depth of 78 feet) that rely on 

induced infiltration of stream water can 

be the most vulnerable to contamination. In fact, studies show that water 

can move from streams into adjacent 

public-supply wells quickly, within days 

to weeks. (See p. 13.)

Pesticides were detected less 

frequently and at lower concentrations in ground water 

than in streams

Thirty-one pesticides were detected 

in 96 water samples collected from 

wells completed in the buried-valley 

aquifer. These include 16 herbicides, 

11 herbicide degradates, 2 fungicides, 1 

insecticide, and 1 insecticide degradate 

(fig. 14). About 63 percent of the groundwater samples contained at least one 

detectable pesticide (or degradate), and 

almost half the samples contained two 

or more pesticides. Seventeen pesticides 

were detected in samples from a publicsupply well receiving induced infiltration 

of water from the Great Miami River and 

from a shallow monitoring well (18 feet 

deep) in an agricultural area overlain by 

cropland. The highest concentration of an 

individual pesticide degradate measured 

was 3.6 μg/L, for the ESA degradate of 

Figure 13. Similar concentrations of atrazine 

and atrazine degradates were measured in 

the Great Miami River at Hamilton. Concentrations of acetochlor degradates, however, were 

much higher than concentrations of the parent 

herbicide.

Box 5—What are degradates and why are they important? 

When released into the environment, synthetic organic compounds—including pesticides, VOCs, and pharmaceuticals—may break down by 

either chemical or biological processes in water, soil, stream sediment, and plant and animal tissue. These processes can result in one or more 

breakdown products (hereinafter termed “degradates”). For example, the herbicide atrazine breaks down to deethylatrazine (DEA), deisopropylatrazine (DIA), deethyldeisopropylatrazine (DEA–DIA), and hydroxyatrazine. Some degradates are produced by the breakdown of more than 

one parent compound. For example, DIA also can form from the breakdown of the herbicides simazine and cyanazine. Degradates, particularly 

those of high-use herbicides such as atrazine and metolachlor, are often detected more frequently and at higher concentrations in streams and 

ground water than are their parent compounds (Clark and others, 1999; Kolpin and others, 2000). 

Although many degradates are believed to be less toxic than their parent compounds, some degradates have equal or greater toxicity than 

the parent compounds (Sinclair and Boxall, 2002). Physical and chemical properties of the degradate may allow it to persist at higher concentrations and for a longer time. Even if a degradate is less toxic than the parent compound, its enhanced stability (or mobility) could lead to 

increased exposure in humans and aquatic organisms. Health concerns about degradates has prompted USEPA to consider selected atrazine 

degradates in the reregistration process for atrazine (U.S. Environmental Protection Agency, 2002), although the implications for the atrazine 

drinking-water standard are uncertain at this time.

alachlor, and the highest parent concentration was 1.3 μg/L, for the fungicide 

benomyl. Concentrations of most of the 

pesticides were low; maximum concentrations for 16 of the 31 pesticides 

detected were less than 0.05 μg/L (fig. 

14). None of the pesticides had concentrations greater than USEPA drinkingwater benchmarks, although only 11 

benchmarks exist for the 31 pesticides 

and degradates detected. (See Box 3.)

Detection frequencies, concentrations, and number of pesticides 

detected in ground water were less than 

those in stream water. For many of 

these pesticides, the chemical stability 

or mobility is not sufficient for them to 

move and persist in the ground-waterflow system long enough to reach a 

well. In addition, relatively impermeable clay (in glacial till) can impede the 

vertical movement of pesticides toward 

the water table. 

Herbicide degradates were 

the dominant form of pesticides found in ground water

Degradates of atrazine, alachlor, 

acetochlor, and metolachlor were the 

most frequently detected contaminants 

in ground water in the Great and Little 

Miami River Basins (fig. 14). Atrazine 

and metolachlor, which were detected 

in nearly all stream samples, were 

detected in less than 15 percent of the 

ground-water samples. The degradates 

of atrazine, acetochlor, alachlor, and 

metolachlor, however, made up more 

than 90 percent of the total pesticide 

concentration in 80 percent of the 

samples collected from domestic and 
12 Water Quality in the Great and Little Miami River Basins

Figure 14. Pesticides frequently detected in streams were 

found much less frequently in ground water. Degradates 

of high-use herbicides were the most frequently detected 

pesticides in ground water.

public-supply wells. Although the human-health implications 

of pesticide degradates are not currently known (see Box 5), 

this finding suggests that monitoring programs that do not 

analyze for degradates will have an incomplete picture of 

pesticide occurrence in the buried-valley aquifer system in 

the Study Unit. 

Pesticides were detected most frequently and at 

highest total concentrations in public-supply wells 

near streams

Pesticides were detected more frequently in water samples 

from public-supply wells near streams (about 60 percent) than in 

domestic wells or in shallow monitoring wells in agricultural and 

urban areas (fig. 15). The median number of pesticides detected 

per public-supply well (9) also was higher than in shallow agricultural wells (3) and domestic wells (1). With some exceptions, 

detection frequencies of pesticide degradates were higher in the 

public-supply wells than in the agricultural and domestic wells 

(fig. 16). Deethylatrazine (DEA) and the ESA degradates of metolachlor and alachlor were detected in more than 80 percent of the 

public-supply wells. Bentazon, atrazine, imazaquin, metolachlor, 

and prometon were detected 2 to 3 times as frequently in publicsupply wells as in agricultural wells. The median concentration of 

pesticides in public-supply wells (1.18 μg/L) was almost 20 times 

the median concentration of the same group of pesticides in shallow agricultural wells (0.06 μg/L) but was similar to the median 

concentration found in samples from the Great Miami River 

(2.11 μg/L). 

 The most likely source of pesticide contamination of the 

high-capacity public-supply wells located near streams is induced 

infiltration of stream water, which can reach the wells in weeks 

or even days. The rate and volume of pumping, along with the 

permeability of streambed sediments and aquifer materials, 

governs the degree of interaction between the stream and shallow 

aquifer and the vulnerability of ground water to contamination. 

Implications of these findings are important because ground-water 

contamination is difficult to reverse. Ground-water flow rates are 

slow compared to streamflow, and a contaminated aquifer can take 

years or even decades to recover.

Figure 15. One or more pesticides were 

detected more frequently in high-capacity 

public-supply wells near streams than in 

either domestic wells or shallow monitoring wells in agricultural or urban areas.
Major Findings 13

Other Organic Compounds 

Volatile organic compounds 

(VOCs)—used in paints, solvents, 

fuels, refrigerants, and fumigants—are 

a water-quality concern because of their 

widespread use, toxicity, and documented 

presence at low concentrations in water 

across the Nation, particularly in urban 

areas. Thirty of the 86 VOCs for which 

samples were analyzed were detected in 

Holes Creek, which drains urban land, and 

in the Great Miami River at Hamilton, 

which drains mixed land uses. Three types 

of VOCs were detected: byproducts of 

drinking-water disinfection called trihalomethanes (THMs), gasoline chemicals, 

and various solvents. All three types were 

detected more frequently in the Great 

Miami River than in Holes Creek, most 

likely because the Great Miami River 

drains a much larger basin, encompasses 

a larger number of industrial and vehicle 

sources, and receives treated wastewater 

from industrial and municipal discharges. 

Chloroform (trichloromethane), 

which is produced during disinfection 

of drinking water and wastewater, was 

detected in 100 percent of the samples 

from the Great Miami River (fig. 17). 

Benzene was the most commonly 

detected gasoline product, in about 70 

percent of the Great Miami River samples. Methyl tert-butyl ether (MTBE), 

a gasoline additive, was detected in 

30 percent of the Great Miami River 

samples but was not detected in Holes 

Creek. Trichloroethylene (TCE) was 

the most commonly detected solvent, in 

more than 60 percent of the samples from 

the Great Miami River. Concentrations of 

VOCs were low, however, and all were 

well below drinking-water standards and 

aquatic-life guidelines.

VOCs were detected less frequently 

in ground water than in streams. A total 

of 20 VOCs were detected in 70 water 

samples from domestic, public-supply, 

and shallow monitoring wells in urban 

areas. Similar to its presence in streams, 

chloroform was the most frequently 

detected VOC in ground water—in 

more than one-half of the samples from 

public-supply wells and almost 30 

percent of the samples from domestic 

wells and shallow monitoring wells in 

urban areas. A commonly used solvent, 

1,1,1-trichloroethane, was detected in 

almost half of the shallow monitoring 

wells in urban areas. MTBE, which is 

prevalent in ground water in many parts 

of the Nation, was detected in 13 percent 

of public-supply wells. MTBE was not 

detected in domestic wells or monitoring 

wells in urban areas. Gasoline chemicals 

were rarely detected in ground water in 

the Study Unit; toluene (methylbenzene) 

and 1,2,4-trimethylbenzene were the only 

gasoline chemicals detected. As in stream 

samples, VOC concentrations in groundwater samples were low and all were 

well below drinking-water standards and 

aquatic-life guidelines. Chloroform, tetrachloroethylene, and bromodichloromethane were the only chemicals detected in 

ground water at concentrations greater 

than 1 μg/L.

Household chemicals and 

pharmaceuticals were 

detected in streams and ground 

water

Human health and safety have 

improved through everyday use of 

household and pharmaceutical chemicals, but these chemicals get into our 

–

Figure 16. Infiltration of stream water containing pesticides is one explanation for 

why pesticides and degradates were found most often and at highest concentrations in water pumped from high-capacity public-supply wells near streams.
14 Water Quality in the Great and Little Miami River Basins

products, detergents, drugs and their degradates, flame retardants, and animal-waste 

products, and nine of the chemicals are 

known or suspected endocrine disruptors.

Seven of the household chemicals 

and pharmaceuticals were detected in 

more than one-half the samples from the 

Great Miami River. Acetyl hexamethyl 

tetrahydronaphthalene (AHTN), a musk 

fragrance used in many personal care 

products, was detected in 100 percent of 

the samples; caffeine and acetaminophen 

were detected in more than 75 percent 

water supplies when they are disposed 

of in wastewater. As a result, many of 

these chemicals have been found at very 

low concentrations in streams across the 

country (Kolpin and others, 2002). The 

effects that many of these chemicals may 

have on humans or aquatic life at low 

concentrations is unknown, but several 

are known or suspected endocrine disruptors. (See Box 2.) 

Samples collected monthly from the 

Great Miami River at Hamilton starting 

in October 2000 and ending in September 2001, and from 25 wells in urban 

areas from October through December 

2001, were analyzed for household 

chemicals and pharmaceuticals. Of a 

total of 116 household chemicals and 

pharmaceuticals for which the samples 

were analyzed, 61 were detected at least 

once in samples collected in study-unit 

streams and ground water. Most of these 

chemicals were detected more frequently 

in streams than in ground water (fig. 

18). Twenty-five of the most frequently 

detected chemicals include personal care 

Glacial outwash deposits, the 

source of drinking water to most residents of the Study Unit, are composed of 

sand and gravel that store and transmit 

large amounts of water. The same properties that make these deposits an excellent aquifer, such as shallow depth and 

permeable material, also make ground 

water vulnerable to contamination. 

Vulnerability to contamination depends 

on how fast the aquifer is recharged 

(ground-water age), which is controlled 

by various factors, including depth to 

the water; land use; presence or absence 

of any overlying, poorly permeable clay 

layers; amount of water pumped; and 

distance from sources of contamination. 

Shallow monitoring wells (less than 50 

feet deep) that tap recently recharged 

ground water are generally considered 

to be most vulnerable to contamination 

by chemicals applied to or spilled on 

the land, so that the quality of shallow ground water tends to reflect over 

lying land use. For example, the highest 

concentrations of nitrate were found in 

shallow ground water beneath agricultural 

areas (see p. 19), and highest concentrations of chloride were found in shallow 

ground water beneath urban areas (Shindel and others, 2001; 2002; 2003). 

Domestic wells are typically deeper 

than monitoring wells and tap older 

ground water (recharged within the past 

few years or decades); they pump small 

amounts of water and, if properly constructed, are less vulnerable to contamination than are public-supply wells adjacent 

to streams. Public-supply wells have long 

well screens, pump large volumes of 

water, and commonly depend on induced 

infiltration of stream water to sustain 

high yields. Because of location and well 

construction, the public-supply wells have 

three potential sources of contamination: 

contaminants introduced at land surface, 

contaminants found deeper within the 

aquifer, and contaminants in stream water. 

Transport of contaminants to shallow, unconfined parts of the aquifer unaffected by heavy pumping may require a 

few months to a few years. Results of age 

dating by means of tritium and helium 

isotopes and sulfur hexafluoride suggest 

that movement of ground water from 

the water table to shallow parts of the 

aquifer (10 to 50 feet deep) takes a year 

or two. (See Plummer and others [1993] 

for description of age-dating techniques.) 

Deeper monitoring wells and domestic 

wells are recharged more slowly, with 

median ground-water ages of a decade or 

more. Age dating of water from highcapacity public-supply wells potentially 

affected by stream-water infiltration 

was not attempted because such mixed 

waters do not yield reliable ages. Studies 

by Rowe and others (1999) and Sheets 

and others (2002), however, suggest that 

water travels from streams to adjacent 

public-supply wells within relatively 

short periods (days to months).

Urban monitoring

well

River

Public-supply

well

Domestic

well

Agricultural

monitoring

well

Glacial outwash (sand and gravel)

Clay-rich glacial deposits

Water table

Not to scale

FEET

0

200

Hydrogeologic setting, ground-water age, well depth, and construction are key to understanding water quality
Major Findings 15

Figure 17. Volatile organic compounds were detected more frequently in 

streams than in ground water in the Study Unit.

of samples. In contrast to pesticides, no 

seasonal pattern was observed in the 

numbers, types, or concentrations of 

chemicals found.

A subset of 58 household chemicals and pharmaceuticals were analyzed 

from samples collected during summer 2001 from 29 small streams with 

varied land uses. Forty-six chemicals 

were detected. Seven chemicals were 

detected in more than one-half of the 

samples: beta-sitosterol and cholesterol 

(animal/plant waste products), caffeine 

(a stimulant), NPEO–2 (a detergent 

degradate), phenol (multiple uses), 

tri(2-chloroethyl)phosphate (a plasticizer 

and flame retardant), and triclosan (a 

disinfectant/antibacterial chemical). The 

summed concentration of all chemicals 

detected in a single sample ranged from 

0.26 to 14.1 μg/L, with a median of 3.7 

μg/L. No particular group of chemicals 

was detected more frequently than any 

other in the small streams, but more 

chemicals were detected in streams draining larger amounts of urban land. (See 

p. 25–28.)

Fewer household chemicals and 

pharmaceuticals (16 out of 116 for which 

samples were analyzed) were detected in 

ground water beneath recently developed (post-1960) urban areas than in 

streams. One or more of the 16 chemicals 

detected, however, were present at very 

low concentrations in 19 of 25 shallow 

monitoring wells in urban areas. The 

most frequently detected chemical in 

ground water was 1,7-dimethylxanthine 

(a caffeine metabolite), present in 28 

percent of the samples. Most of the 

chemicals detected in ground water were 

drugs and their degradates (fig. 18).

Concentrations of some synthetic organic compounds in 

the Study Unit ranked among 

the highest in the Nation

In addition to polychlorinated 

biphenyls (PCBs) (see story on page 

17), five organochlorine insecticides or 

degradates (cis- and trans-chlordane, 

cis- and trans-nonachlor, and aldrin) 

were detected in fish tissue at concentrations that were among the highest in 

the Nation (table 2, p. 17). The most 

common organochlorine insecticides in 

the Study Unit (cis- and trans-chlordane, 

trans-nonachlor, and dieldrin) also were 

among the most frequently detected 

nationally. These insecticides, whose 

registrations were canceled during the 

1970s and 1980s, were used mainly 

for termite control and crop protection. 

They are classified as endocrine disruptors (see Box 2) and are known to cause 

liver and kidney lesions in fish. Similar 

to findings for PCBs (see p. 17), organochlorine insecticides were detected more 

frequently in fish tissue (41 percent) than 

in bed sediment (16 percent) in the Study 

Unit. The New York Fish Flesh Criteria 

(NYFFC) for the protection of fisheating wildlife (200 μg/kg [micrograms 

per kilogram] wet weight [Newell and 

others, 1987]) for total DDT concentration was exceeded in fish tissue (311μg/

kg wet weight) from the Mad River. The 

TEL (see Box 3) for heptachlor epoxide 

(0.6 μg/kg dry weight) was exceeded in 

sediment from Holes Creek (1.1 μg/kg 

dry weight).

Data collected by NAWQA were 

supplemented by extensive bed-sediment 

and fish tissue data collected at more than 

200 sites within the Study Unit by State 

agencies in Ohio and Indiana (Janosy, 

2002). Dieldrin was the most commonly 

detected organochlorine insecticide in 

fish tissue (at 91 percent of the sites) 

and bed sediment (at 39 percent of the 

sites). Concentrations of dieldrin in bed 

sediment exceeded sediment-quality 

guidelines more often (at 12 sites) than 

concentrations of any other organochlorine insecticide.

Elevated concentrations of semivolatile organic compounds (SVOCs), such 

as polycyclic aromatic hydrocarbons 

(PAHs), were prevalent in bed sediment 
16 Water Quality in the Great and Little Miami River Basins

in the Study Unit. Total concentrations 

of PAHs in sediment from Holes Creek, 

Great Miami River at Hamilton, and 

Little Miami River at Milford ranked 

among the highest 25 percent nationwide 

for urban and mixed-land-use streams 

sampled in the NAWQA Program. 

Forty-seven percent of SVOCs detected 

were PAHs. Ten PAHs were detected at 

concentrations exceeding recommended 

sediment-quality guidelines, although 

phenanthrene was the only SVOC to 

exceed a PEL. (See table 2.) Many of 

the most frequently detected SVOCs in 

study-unit sediment are components of 

crude oil and coal tar and are released to 

the environment through vehicle emissions; coal, oil, and wood-burning stoves 

and furnaces; and steel and coke production (Janosy, 2002).

Naturally Occurring 

Trace Elements

From a national perspective, traceelement concentrations in sediment in 

the Study Unit generally were below 

national medians for streams sampled by 

the NAWQA Program. Although all trace 

elements of interest were detected at all 

eight study-unit streams, concentrations 

were generally below national medians. 

No PELs were exceeded, but TELs were 

exceeded for five elements: arsenic, 

chromium, cadmium, lead, and zinc. 

Certain trace elements, such as arsenic, 

occur naturally in the Study Unit and can 

be redistributed in the environment by 

human activities, such as waste disposal 

and fossil-fuel combustion. They also 

may enter aquatic ecosystems through 

point- and nonpoint-source releases and 

atmospheric deposition. 

Arsenic, a naturally occurring element associated with the dissolution of 

arsenic-bearing minerals such as pyrite 

and iron hydroxides (Welch and others, 

2000), is found in ground water in some 

parts of the Study Unit. Arsenic was 

detected in 54 percent of the samples 

from domestic, public-supply, and shallow monitoring wells in agricultural and 

urban areas. Elevated concentrations of 

arsenic were typically found in groundwater environments where dissolution 

of arsenic-bearing minerals is favored, 

as indicated by low concentrations of 

nitrate and dissolved oxygen and high 

concentrations of iron, manganese, and 

ammonia—conditions typically found at 

Figure 18. Commonly used household chemicals and pharmaceuticals are detected more frequently in streams 

than in ground water. [n, number of samples; *, known or suspected endocrine disruptor (see Box 2) (Zaugg, 2002); 

NA, data not available; AHTN, 6-acetyl-1, 1, 2,4, 4,7-hexamethyltetraline; NPEO–2, nonylphenol diethoxylate]
Major Findings 17

Fish tissue1 (percentile)

Fish-tissue

guidelines

Bed sediment

1

(percentile)

Sediment-quality guidelines

(number of exceedances)

Land

use Site cis -Chlordane

trans -Chlordanecis -Nonachlortrans -NonachlorAldrinDieldrinPCBsNumber ofexceedancesPhenanthrenePyreneFluorantheneArsenicChromiumLeadZincProbable EffectLevelThreshold EffectLevel

Mixed

Little Miami River at Milford 95 95 95 x 95 50 1 (PCB) x 75 75 50 25 50 50 0 14

Great Miami River at Hamilton 95 95 90 95 max 90 95 1 (PCB) 75 75 75 50 25 50 50 1 (phenanthrene) 14

Urban

Holes Creek near Kettering 75 75 75 75 x 50 75 1 (PCB) 25 25 25 75 25 x x 0 13

Agriculture

E. F. Little Miami River near Williamsburg x x 75 50 x 50 75 1 (PCB) x 50 50 50 50 50 75 0 4

Whitewater River near Nulltown 90 90 x 90 x 75 90 1 (PCB) x 50 50 50 x 50 25 0 2

Stillwater River near Union 90 95 95 x 95 75 1 (PCB) x 50 50 75 50 50 75 0 3

Great Miami River near Tipp City 75 90 90 x 75 95 1 (PCB) 90 90 90 75 x 75 75 0 12

Mad River near Springfield max

maxmaxmax

x 75 x 1(total DDT) 75 75 90 75 25 50 50 0 8

1

Percentile ranking of concentration with respect to NAWQA studies nationwide; x, less than 25th percentile; max, maximum found nationally

Whole Fish

Wildlife guideline

Bold outline indicates exceedance by total PCBs

Highest 25 percent

Second highest 25 percent

Lowest 50 percent

(all with no detections)

Sum of total PCB concentrations

Bed Sediment

Sum of total PCB concentrations

Total PCBs in Agricultural Streams

Highest 15 percent Lowest 85 percent (all with no detections)

EXPLANATION

EXPLANATION

Great and Little

Miami River

Basins

Great and Little

Miami River

Basins

Table 2. Concentrations of many organic compounds in fish tissue and sediment ranked in the top 25 percent of all 

streams sampled in the NAWQA Program. Trace-element concentrations in sediment, however, were typically at or 

below national medians.

Concentrations of PCBs in fish tissue are among the highest in the Nation

Although production of polychlorinated biphenyls (PCBs) was banned 

in the United States in 1979, PCBs are still present in fish tissue from the 

Great and Little Miami River Basins, frequently at concentrations near or at 

the maximum concentrations found nationwide. PCB concentrations in fish 

tissue at four of five agricultural streams in the Study Unit were among the 

highest in the Nation, ranking in the top 25 percent of 208 streams sampled 

nationwide by the NAWQA Program. Tissue samples from the urban 

and mixed-land-use streams also ranked in the top 25 percent of streams 

sampled nationally. Elevated concentrations of PCBs in fish at seven of the 

eight sampled sites exceeded the New York Fish Flesh Criteria (NYFFC) 

for the protection of fish-eating wildlife (110 μg/kg wet weight) (Newell 

and others, 1987). Common carp, targeted for this study, are potentially 

exposed to PCBs through contact with contaminated sediments or consumption of contaminated plant and animal material. Study-unit results were 

similar to national results; elevated concentrations of PCBs in fish tissue 

were found at many sites where concentrations of PCBs in sediment were 

below detection levels. Frequent detection of PCBs and elevated concentrations in fish tissue is related to the ability of PCBs to bioaccumulate in fish 

and fish-eating wildlife. Possible sources of PCBs in streams and sediment 

include atmospheric deposition, landfills, industrial facilities, incinerators, 

and leakage of PCB-containing materials still in use, such as electrical 

transformers. (Use of PCBs in equipment already in service was not banned 

in 1979.) Because of past widespread use and their environmental persistence—half-lives of individual PCBs in sediment range from months to 

years—PCBs are expected to remain in the environment for the foreseeable 

future (U.S. Environmental Protection Agency, 1999b). 
18 Water Quality in the Great and Little Miami River Basins

Concentrations of radon were greater than 300 pCi/L (picocuries per liter), the proposed USEPA drinking-water standard, in 65 percent of 104 wells sampled in the Great and Little Miami River Basins. Public water systems must comply 

with the new standard beginning January 23, 2006. Concentrations of radon ranged from 100 to 1,390 pCi/L, with a median 

concentration of 395 pCi/L. 

Concentrations of radon did not vary significantly among domestic, public-supply, and shallow monitoring wells and did 

not vary significantly with well depth or ground-water age. Radon concentrations in ground water underlying the Study Unit 

are about average when compared to concentrations in wells tapping glacial aquifers in 13 other NAWQA Study Units across 

the Nation. Because sources of radon are related to the geologic material making up the aquifer, only the data from those 

NAWQA Study Units with glacial aquifers were used in comparisons of radon concentrations. 

Radon is a colorless and odorless radioactive gas that forms during 

the decay of natural uranium in rocks 

and soil. Radon gas is carried in water 

pumped from wells and is released to the 

air as the water is agitated during domestic uses such as cooking or showering 

(Otton, 1992). Breathing radon increases 

the risk of lung cancer (U.S. Environmental Protection Agency, 1999a). 

Great and

Little Miami

River Basins

Mean concentration of radon in

ground-water samples

-

EXPLANATION

Proposed drinking-water standard for radon commonly was exceeded, 

but concentrations were similar to those in other glaciated areas

Concentrations of mercury in water and sediment were lower than 

the national median, despite higher atmospheric deposition rates

Mercury, a highly toxic trace 

element, is one of the most widespread 

contaminants affecting our Nation’s 

streams. Mercury reaches most aquatic 

ecosystems by way of atmospheric 

deposition. Sources of mercury are 

coal combustion, ore mining, metal 

processing, and waste incineration 

(Krabbenhoft and Rickert, 1997; 

Eisler, 1985–99). Bacteria in sediment 

convert inorganic mercury to the more 

toxic methylmercury, an organic form 

that accounts for 90 to 100 percent of 

the total mercury found in fish tissue. 

Methylmercury, along with PCBs, is 

responsible for most of the human 

fish-consumption advisories issued in 

Ohio and Indiana (Ohio Department 

of Health, 2002; Lanetta Alexander, 

Indiana State Department of Health, 

written commun., 2003). 

 Analyses of samples collected 

in the Great and Little Miami River 

Basins in 1998 indicate that concentrations of total mercury and methylmercury in water and sediment were near 

or below the median for 106 streams 

sampled across the Nation, even though 

the atmospheric deposition rate of 

mercury in the Study Unit was the sixth 

highest among the 21 NAWQA Study 

Units examined (Krabbenhoft and others, 1999). The relatively low concentrations, despite higher atmospheric deposition, most likely are a consequence of 

the general absence of environmental 

conditions associated with high rates 

of methylation (such as high wetland 

density, organic-rich sediment, and low 

pH) in the Study Unit.

Concentrations of total mercury 

(most of which is methylmercury) in 

sport-fish fillets also were relatively 

low when compared to those in other 

NAWQA Study Units (ranking below 

Agricultural

Mixed land use

Urban

Study-unit data 

by site type

CONCENTRATION

National data

Range

Median

Fish fillet

(micrograms

per gram)

Sediment

(nanograms

per gram)

Water

(nanograms

per liter)

EXPLANATION

� �

the national median) (Janosy, 2002). 

The highest concentrations of mercury 

in fish fillets sampled from the Study 

Unit (0.52 and 0.36 μg/g (microgram 

per gram), wet weight) were found in 

smallmouth bass collected from the 

East Fork Little Miami River near Williamsburg, Ohio; these concentrations 

exceeded the USEPA human-health 

criterion of 0.3 μg/g (U.S. Environmental Protection Agency, 2001). 

No correlations were found between 

concentrations of mercury in fish tissue 

and methylmercury concentrations in 

water or sediment, despite the finding 

nationally that methylmercury concentrations in water correlated strongly 

with bioaccumulation rates in fish.
Major Findings 19

Figure 19. Manure from animals can 

be an important source of nutrients to 

some streams in the Great and Little 

Miami River Basins, but most nitrogen 

and phosphorus in agricultural streams 

is from fertilizer applied to cropland. 

Discharge of municipal and industrial 

wastewater is a significant source of 

nutrients to large streams in the Study 

Unit, particularly during low streamflow.

Figure 20. Concentrations of nitrate were 

highest in samples collected in agricultural 

streams during a runoff event. 

depths greater than 50 feet in the aquifer. 

High concentrations of arsenic also were 

associated with high concentrations of 

strontium and silica, constituents that 

indicate the relative amount of waterrock reaction (Rowe and others, 1999). 

Concentrations of arsenic generally were 

lower than the USEPA drinking-water 

standard of 10 μg/L (reduced from 50 

μg/L in August 2002, but public-water 

suppliers must comply with the 10-μg/L 

standard beginning January 23, 2006). 

Five of 104 ground-water samples collected in the Study Unit exceeded the 

standard of 10 μg/L. Concentrations in 

two samples, one from a 100-foot-deep 

domestic well and the other from a 45-

foot-deep agricultural monitoring well, 

exceeded the older standard of 50 μg/L. 

The five samples with arsenic 

concentrations above the drinking-water 

standard were from wells deeper than 23 

feet and in ground water recharged before 

1982. No significant correlations between 

arsenic concentration, well depth, and 

ground-water age could be identified, 

however, when data from all wells were 

considered. Although the arsenic drinking-water standard was exceeded in only 

five samples, further investigation is warranted because of arsenic’s toxicity and 

unpredictable occurrence in the aquifer.

Nutrients—Too Much of 

a Good Thing

Human activities in the Study 

Unit—including agricultural and urban 

uses of fertilizer, agricultural use of 

manure from confined animal feeding 

operations, and disposal of domestic and 

municipal wastewater—have contributed 

to increases in nitrogen and phosphorus

in streams and nitrate in shallow ground 

water (fig. 19). Plants need nutrients 

to grow and produce good crop yields; 

however, nutrients applied to the land 

can seep into ground water or run off to 

streams during rainstorms. 

Excessive nitrogen and phosphorus 

in streams can contribute to overgrowth 

of algae and other nuisance plants, whose 

death and subsequent decay can cause 

oxygen levels in streams to decline 

substantially during warm weather and 

at night. Some sensitive aquatic organisms cannot live in low-oxygen environments. High nutrient concentrations in 

streams have also been associated with 

an increase in the number of deformities, 

eroded fins, lesions, and tumors on fish 

(Ohio Environmental Protection Agency, 

1995, 1997).

Ingestion of drinking water with 

high nitrate concentrations can cause low 

oxygen levels in the blood of infants, 

a potentially fatal condition known as 

methemoglobinemia, or “blue baby 

syndrome” (Spaulding and Exner, 1993). 

Because of these health concerns, the 

USEPA set the drinking-water standard 

for nitrate at 10 mg/L (milligrams per 

liter) (U.S. Environmental Protection 

Agency, 1986).

Drinking-water standard for 

nitrate was exceeded more 

frequently in ground water than 

in streams, except during spring 

runoff

Concentrations of nitrate exceeded 

the drinking-water standard more frequently in ground water than in agricultural, urban, and mixed-land-use streams 

(fig. 20). Specifically, nitrate concentrations in 10 percent of the ground-water 

samples (10 of 104 samples) and less 

than 1 percent of the stream samples 

exceeded the drinking-water standard of 

10 mg/L. In streams, this pattern can vary 

seasonally, however, particularly during 

spring runoff following fertilizer application to cropland. Samples collected May 

19–20, 2000, at 30 stream sites in the 

agricultural Stillwater River Basin during a runoff event had a median nitrate 

concentration of 22 mg/L; the maximum 

concentration was 45 mg/L. Most of the 

nitrogen in these stream samples came 

from soil nitrogen and inorganic fertilizer, as indicated by nitrogen isotope 

analysis. (See p. 23.) 

Elevated concentrations of nitrate 

in ground water were strongly related to 

land use, well depth, and age of water 

(fig. 21). For example, the median concentration of nitrate in shallow monitoring wells (median depth 26 feet) in 

agricultural areas was 5.9 mg/L and was 

higher than that for shallow monitoring 

wells (median depth 39 feet) in urban 

areas (median about 2.5 mg/L). 

In addition, concentrations of nitrate 

are greater in wells less than 60 feet deep, 

generally recharged since 1990, than in 

the deeper wells, which were recharged 

before 1990. As water moves deeper 

into the aquifer system, chemicals such 

as nitrate can change. For example, in 

low-oxygen (about 1.0 mg/L) conditions, 

nitrate is broken down to nitrogen gas 

and water (referred to as denitrification), 

such as documented in ground water 

underlying the Dayton area (Rowe and 

others, 1999). The relatively slow movement of ground water, combined with the 

right environmental conditions, allows 

the aquifer to naturally rid itself of nitrate 

with depth. 
20 Water Quality in the Great and Little Miami River Basins

Figure 23. In the spring, nonpoint 

sources (instream loads) were the 

largest contributor of nitrate and 

total phosphorus to the Great Miami 

River at Hamilton. In summer, point 

sources became an important contributor.

Commercial fertilizer applications to agricultural lands are 

greatest nonpoint source of 

nutrients 

Major nonpoint sources of nutrients 

to the Study Unit include atmospheric 

deposition and applications of manure 

and commercial fertilizer to agricultural 

lands. Commercial fertilizer accounted 

for an estimated two-thirds of nitrogen 

and phosphorus applied or deposited 

to the Great Miami River Basin during 

the 2-year monitoring period October 

1998 through September 2000 (Reutter, 

2003). Cropland applications of manure 

generated from a high number of confined animal-feeding operations in the 

Stillwater River Basin accounted for 

about 9 percent of the nitrogen applied 

or deposited on the Great Miami River 

Basin. Commercial fertilizer accounted 

for about 74 percent of nitrogen and 81 

percent of phosphorus applied or deposited on the Little Miami Basin (fig. 22). 

Although the amounts of nutrients 

reaching streams generally increase as 

nonpoint nutrient inputs increase, not all 

nutrients applied or deposited onto the 

basins enter the streams. Only 13 percent 

of total nitrogen from nonpoint sources 

Figure 21. Nitrate concentrations tend 

to be highest in ground water recharged 

after 1990 and in wells less than 60 feet 

deep.

Figure 22. Most nonpoint total nitrogen and total phosphorus applied to or 

deposited on the Great and Little Miami 

River Basins was from commercial 

fertilizer.

was transported to the Great Miami and 

Little Miami Rivers and only 5 percent of 

total phosphorus from nonpoint sources 

was transported to the rivers (Reutter, 

2003). This result is consistent with the 

fact that nitrate, the dominant form of 

nitrogen in study-unit streams, tends to 

dissolve in water and be transported readily with surface and tile-drainage runoff. 

In contrast, most phosphorus occurs as 

solids, or is bound to soil, and is less 

likely to dissolve in water that runs off to 

streams or seeps to ground water; hence, 

most phosphorus from nonpoint sources 

is transported during large storms when 

heavy runoff and high streamflows mobilize soil- and sediment-bound phosphorus. Total nitrogen from nonpoint sources 

accounted for 78 percent of the instream 

load of the Great Miami River at Hamilton and 66 percent of the instream load 

of the Little Miami River at Milford over 

the 2-year monitoring period. Total phosphorus from nonpoint sources accounted 

for 48 percent of the instream load of the 

Great Miami River at Hamilton and 52 

percent of the instream load of the Little 

Miami River at Milford. Point-source 

discharges of phosphorus were primarily from wastewater-treatment plants in 

urban areas. 

Nutrient loads in streams varied 

seasonally

During the 2-year monitoring period, 

nutrient loads in the study-unit streams 

were highest during winter and spring and 

lowest during summer and autumn. For 

example, nitrate loads to the Great Miami 

River at Hamilton decreased from a peak 

of about 3,000 tons in January 1999 to 

less than 50 tons in September 1999 

(fig. 23), mostly in response to drought 

in summer and autumn 1999. Nutrient 

loads from point-source discharges to 

the Great Miami River at Hamilton were 

actually higher than the computed nitrate 

and total phosphorus instream loads during much of summer and autumn 1999. 

Thus, during periods of low streamflow, 

point-source discharges can be the dominant source of nutrients in streams. The 

difference between nutrient inputs and 

actual loads also indicates that uptake of 

nutrients by algae and other aquatic plants 

is an important process during summer 

and autumn months. 
Major Findings 21

Median concentration of nitrate,

in milligrams per liter.

Each circle represents a ground-water study.

Highest (greater than 5)

Medium (0.4 to 5)

Lowest (less than 0.4)

Background concentration

Bold outline indicates median values greater than background concentration (2 milligrams per liter)

Average annual total nitrogen input,

in pounds per acre, by county, for 1995–98.

Inputs are from fertilizer, manure, and the

atmosphere.

Greater than 25

6 to 25

Less than 6

SHALLOW GROUND WATER IN AGRICULTURAL AREAS

NITRATE

No data available

EXPLANATION

Great and Little Miami

River Basins

Total nitrogen input,

in pounds per acre

Greater than 25

6 to 25

Less than 6

Greater than 5

2 to 5

Less than 2

Phosphorus input,

in pounds per acre

Mean annual concentration,

in milligrams per liter

Less than 0.6

0.6 to 3

Greater than 3

Less than 0.05

0.05 to 0.3

Greater than 0.3

Mean annual concentration,

in milligrams per liter

EXPLANATION

EXPLANATION

Great and

Little Miami

River Basins

Great and

Little Miami

River Basins

-

- High nutrient concentrations in streams draining 

mixed-land-use areas are a concern locally and 

nationally

The Ohio Environmental Protection Agency (OEPA) has attributed excessive algal growth to high concentrations of nutrients at 

several locations in the Great Miami River between Dayton and the 

Ohio River. The OEPA also reported that elevated nutrient loads 

were associated with a large number of deformities, eroded fins, 

lesions, and tumors on fish from the Great and Little Miami Rivers 

(Ohio Environmental Protection Agency, 1995, 1997).

Mean annual concentrations of nitrogen and phosphorus 

for the Great and Little Miami Rivers (generally greater than 3 

and 0.3 mg/L, respectively) were among the highest reported for 

large, mixed-land-use streams monitored by the NAWQA Program 

nationwide. Goolsby and others (1999) found that the Great Miami 

River Basin produced high yields of nitrogen (5.7 tons per square 

mile) and phosphorus (700 pounds per square mile) in comparison 

to the rest of the Mississippi River Basin, which yielded 1.4 tons 

per square mile of nitrogen and 240 pounds per square mile of 

phosphorus. The transport of large amounts of nutrients from the 

Mississippi River Basin to the Gulf of Mexico, particularly transport associated with spring runoff, has increased algal growth in the 

Gulf of Mexico and led to seasonal oxygen depletion (hypoxia).

Nutrients in mixed-land-use streams and nitrate in shallow 

agricultural wells were among the highest in the Nation 

High nitrate concentrations in shallow 

ground water common in agricultural 

areas

Agriculture is a major industry in the Study Unit, 

and tons of fertilizer are applied to the land surface 

annually to increase crop yields. The underlying shallow aquifer is composed of highly permeable sand and 

gravel and is capable of transmitting large amounts of 

water. Land use, high permeability, and shallow depth 

increase the vulnerability of the buried-valley aquifer 

to contamination. Because of these conditions, the 

median concentration of nitrate (5.9 mg/L) in shallow 

monitoring wells screened in sand and gravel deposits in agricultural areas was among the highest in the 

Nation, ranking in the upper 25 percent of all values. 
22 Water Quality in the Great and Little Miami River Basins

Phosphorus concentrations 

have decreased since 1974 

in the Great Miami and Little 

Miami Rivers

Concentrations of total phosphorus 

decreased from 1974 through 2000 in 

Little Miami River at Milford and Great 

Miami River at Hamilton, both of which 

receive numerous wastewater and other 

point-source discharges (fig. 24). Specifically, total phosphorus concentrations 

decreased about 40 percent in the Little 

Miami River at Milford and 50 percent 

in the Great Miami River at Hamilton. 

Decreases are likely due to increased use 

of phosphorus-free detergents, increased 

adoption of no-till farming and other 

best-management practices that reduce 

soil transport to streams, and improved 

wastewater treatment. Benefits have been 

reported by the Ohio Environmental Protection Agency (1995, 1997), including 

improved habitat and aquatic community response for many stream sections. 

Despite declining nutrient concentrations, median concentrations of total phosphorus for the Great and Little Miami Rivers 

were still above the USEPA recommended goal of 0.1 mg/L. 

Highest nitrogen concentrations in streams were in 

agricultural areas, but 

highest phosphorus 

concentrations were in 

streams with numerous 

point sources

Concentrations of nitrogen 

and phosphorus in study-unit 

streams varied among land uses 

(fig. 25). For example, Holes 

Creek, which drains urban areas, 

had the lowest flow-weighted 

mean concentration for nitrogen (about 2 mg/L), whereas the 

agricultural Stillwater, Mad, and 

Upper Great Miami Rivers had 

the highest (greater than 5 mg/L). 

The highest flow-weighted mean 

concentrations of total phosphorus 

(about 0.4 mg/L) were detected in 

the Great and Little Miami Rivers, 

which drain a mix of land uses and 

receive discharge from numerous 

wastewater-treatment plants at or downstream from Dayton. Total phosphorus 

was elevated not only in the mixed 

streams; in fact, the flow-weighted mean 

concentration of total phosphorus in 

streams draining all land uses exceeded 

the USEPA goal for total phosphorus 

of 0.1 mg/L. This goal is designed to 

prevent excessive growth of algae and 

other aquatic plants in flowing streams 

that do not discharge directly into lakes 

or impoundments. This goal also was 

exceeded in most samples collected from 

agricultural streams in the Stillwater 

River Basin during spring runoff. The 

median concentration of total phosphorus was 0.34 mg/L, and the maximum 

concentration was 0.73 mg/L. 

Ground water contributed 

nitrate to some streams 

Concentrations of nitrate in stream 

water during periods of low streamflow 

were significantly correlated with the 

amount of base flow (fig. 26). Both the 

Mad River and Whitewater River drain 

basins in which sand-and-gravel outwash deposits discharge large quantities 

of ground water to streams (fig. 1). For 

streams that do not receive large quantities of effluent from wastewater-treatFigure 25. Agricultural streams had the 

highest total nitrogen concentrations, 

whereas mixed-land-use streams had the 

highest total phosphorus concentrations.

Figure 26. The amount of nitrate in study-unit 

streams in July during the 1999 drought increased 

with increased ground-water discharge (base flow) 

to the stream. Streams with a large base flow, such 

as the Mad and Whitewater Rivers, tend to have 

higher ratios of total nitrogen to total phosphorus.

Figure 24. Annual flow-weighted mean 

concentrations of total phosphorus for 

the Great Miami River at Hamilton and the 

Little Miami River at Milford decreased 

from 1974 through 2000 (data from USGS 

National Water Information System).
Major Findings 23

A snapshot of water-quality conditions in the 

Stillwater River Basin was obtained in May 

2000 by collecting high streamflow (runoff) 

samples from 30 subbasins after a single 

rainstorm (Charles Schalk, U.S. Geological 

Survey, written commun., 2003). Although 

nitrate concentrations in the 30 subbasins 

were significantly correlated with animal 

density, nitrate yields were not (although 

the highest yields among the subbasins were 

associated with the two subbasins having 

the highest animal densities). In a separate 

comparison of daily mean nutrient yields 

estimated for the Stillwater River and the 

adjacent upper Great Miami and Mad Rivers, yields of total nitrogen and phosphorus 

from the Stillwater River Basin were 1.2 to 

1.5 times those of the other basins, which 

have similar levels of crop production but 

do not have substantial numbers of CAFOs 

(Reutter, 2003). This finding suggests that, 

on an annual basis, the large number of 

CAFOs in the Stillwater River Basin probably contribute additional nutrients to the 

Stillwater River. 

Antibiotics, which are used in CAFOs to 

promote growth and prevent disease, have 

recently received increased attention because 

little is known about the fate of these drugs 

and their degradates in the environment, the 

potential health effects on humans and animals exposed to low levels of these chemicals, and their potential role in the development of antibiotic-resistant bacteria (Boxall 

and others, 2003). Lincomycin and erythromycin-H2

O, two antibiotics approved for 

use in animals and humans, were detected 

in runoff and were among the antibiotics 

most frequently detected (19.2 and 21.5 

percent, respectively) in a sampling of 104 

streams nationwide in 1999–2000 (Kolpin 

and others, 2002). Lincomycin was found 

in runoff from seven sites in the Stillwater 

River Basin (23.5 percent) at concentrations that ranged from 0.02 to 0.25 μg/L. 

Erythromycin-H2O, a degradate of the 

antibiotic erythromycin, co-occurred with 

lincomycin at one site at a concentration 

of 0.06 μg/L. Traces of 

lincomycin, sulfamethazine, 

and sulfadimethoxine were 

detected in runoff samples 

from the Stillwater River 

index site in early spring 

2000. No antibiotics were 

detected, however, in subsequent samples collected 

during late spring and summer 2000. Most detections 

of lincomycin (6 of 7) were 

in the northern part of the 

Stillwater River Basin, in 

small subbasins where large 

poultry and 

swine CAFOs 

are located. 

The highest 

concentrations 

of lincomycin 

(0.25, 0.10 

μg/L) were 

in runoff 

from the North Fork Stillwater River and Swamp Creek 

Basins, the two subbasins with 

the highest animal-production 

intensities (Charles Schalk, 

written commun., 2003). 

Campylobacter and Salmonella bacteria were not 

detected in any runoff. 

Escherichia coli bacteria were 

detected at 60 percent of sites, 

and Enterococcus sp. bacteria 

were detected at all sites. 

Samples of Escherichia coli

and Enterococcus bacteria isolated from the runoff samples 

were tested for resistance to 

a wide variety of human and veterinary 

antibiotics (Charles Schalk, written commun., 2003). As expected, resistance to 

some antibiotics that have been used for 

decades in humans and animals (tetracycline 

and sulfa-class antibiotics) was noted in 

some samples. But resistance to antibiotics 

considered critical for treatment of humans, 

such as fluoroquinolones, generally was not 

observed. The exception involved three sites 

where samples of Enterococcus bacteria 

demonstrated resistance to the antibiotic 

vancomycin. This antibiotic is used to treat 

multi-drug-resistant enterococci infections 

in humans and is not approved for use in 

animals.

Confined animal feeding operations (CAFOs) contributed additional nutrients and trace amounts 

of antibiotics to streams

Nitrate concentrations in agricultural runoff increased as 

the number of animals in a basin increased. Despite this, 

nitrogen isotope data from only three basins were consistent with a manure or septic-waste source.

Lincomycin, which is used as a growth promoter for 

swine and poultry, was the only antibiotic detected 

at multiple runoff sites and in more than one sample 

from the Stillwater River index site. 

ment plants, inflowing ground water 

can be an important source of nitrogen, 

particularly during summer months and 

drought periods when streamflow is 

reduced. This condition is especially true 

of nitrate, which was detected in shallow 

ground water beneath agricultural and 

urban areas at concentrations comparable 

to those observed in the Mad and Whitewater Rivers (fig. 26). Because shallow 

ground water generally contains little 

phosphorus, ground-water-dominated 
24 Water Quality in the Great and Little Miami River Basins

streams will tend to have higher ratios of 

total nitrogen to total phosphorus than 

streams draining till-rich (high clay) 

basins whose flows are dominated by 

surface runoff; this condition is especially true in rural areas with few point 

sources of nitrogen and phosphorus. 

Streams dominated by sewage effluent 

at low flows, such as the Little Miami 

River (Buchberger and others, 1997), 

also have high nitrate concentrations but 

will have lower ratios of total nitrogen 

to total phosphorus because of higher 

phosphorus concentrations (fig. 26). For 

ground-water-dominated streams such as 

the Mad and Whitewater Rivers, nitrate 

from base flow could be of consequence 

in establishing nutrient criteria or total 

maximum daily loads (TMDLs).

Responses of algae and fish 

communities to high nutrient 

concentrations are variable 

Mean annual concentrations of 

nitrogen and phosphorus in the Great 

and Little Miami Rivers were among the 

highest in the Nation (p. 21), and individual samples over a range of stream sizes 

included concentrations above the suggested eutrophic threshold (Dodds and 

others, 1998) (fig. 27). Algal growth as 

periphyton (algae attached to the stream 

bottom) or phytoplankton (algae floating 

in the water column) can reach nuisance 

levels when nutrient concentrations are 

high and sunlight is plentiful. Although 

nuisance algal growth was visible at 

several study-unit streams (fig. 28), concentrations of chlorophyll a (an indicator 

of algal productivity) were generally less 

than those that indicate stream eutrophication. This was especially true of 

smaller streams, where vegetation on the 

banks (median 92 percent canopy cover) 

limit light and thus limit undesirable 

algal blooms. In contrast, phytoplankton 

chlorophyll a measured in larger streams 

(median shading 57 percent) was commonly above the suggested eutrophic 

threshold for preventing nuisance algal 

conditions. 

Excess algal growth can cause 

declines in dissolved oxygen to concentrations below those necessary to 

support fish and other aquatic life. 

Although concentrations of dissolved 

oxygen fluctuated as much as 9.3 mg/L 

over 48 hours during summer low-flow 

conditions, minimum concentrations 

measured in small and large streams (4.2 

and 6.4 mg/L, respectively) were above 

the minimum water-quality standard for 

dissolved oxygen in Ohio and Indiana 

streams (4.0 mg/L) (Shindel and others, 

2001, 2002; Ohio Environmental Protection Agency, 2003; Indiana Administrative Code, 2003). Therefore, despite high 

concentrations of nutrients and excessive 

algal growth in places, concentrations of 

dissolved oxygen in study-unit streams 

met current water-quality standards. 

Ecologic response to the high 

nutrient concentrations and excess algal 

growth is mixed: fish-community assessments (Index of Biotic Integrity [IBI] 

scores) indicate a range of fair to excellent fish populations in small and large 

streams considered at risk for eutrophication (fig. 29). This finding indicates 

that, for many streams, factors other than 

high nutrient concentrations (habitat, 

suspended sediment, other contaminants 

in water and sediment) affect fish-community response.

Figure 28. Nuisance algal 

growth, such as the Rhizoclonium sp. algae shown here 

from the Mad River, was visible 

in many study-unit streams. 

31

Figure 29. Fish-community responses 

vary with trophic conditions.

Figure 27. Smaller streams generally had less chlorophyll a than larger 

streams during July 2000 and 2001. 

Median values for nitrogen and phosphorus in larger streams exceeded the 

suggested eutrophic thresholds.
Major Findings 25

Influence of Urbanization 

on Stream Quality

 The chemical, biological, and 

physical condition of streams and rivers 

draining basins undergoing suburban 

and urban development is of concern to 

water-resource managers and the public. 

Research has shown that the quality of 

streams commonly declines as development increases in basins that previously 

were forested or sparsely populated (Paul 

and Meyer, 2001). The overall quality of 

urban streams can be affected adversely 

by degradation of water quality or stream 

habitat, contamination of streambed sediments, or alteration of natural streamflow 

patterns. Combinations of those factors 

often result in loss of sensitive species 

and overall declines in the well-being of 

biological communities.

The influence of suburban and urban 

development in and around the Dayton and Cincinnati metropolitan areas 

was examined at 30 stream sites during summer 2001; land cover upstream 

from these sites ranged from 0 to about 

50 percent urban (fig. 30). This is in 

contrast to other metropolitan areas 

studied by NAWQA, where the proportion of urban land in the most developed 

Figure 31. Total insecticide concentrations and the number of household 

chemicals and pharmaceuticals detected 

in stream water increased with the percentage of urban land in the stream basin. 

Smoothed lines in these and subsequent 

figures are shown where the correlation 

(Spearman rank) between the plotted variables is significant at a probability value 

less than 0.05.)

Figure 30. Basins used to examine the effects of urbanization on water quality 

and aquatic communities in the Dayton/Cincinnati area reflect the recent (post1970) trend of converting agricultural and forested land around large metropolitan areas to residential and commercial uses.

basins exceeded 80 or 90 percent (p. 

28). Streams in the Great and Little 

Miami River Basins with minimal urban 

development were influenced by drainage from intensive row-crop agriculture, 

whereas streams in developed basins 

generally drained residential and commercial lands that formerly were farms 

or undisturbed (forested) lands.

Urban-land percentage affects 

water and streambed-sediment 

chemistry 

 Results from this study showed that 

stream-water quality in the Great and 

Little Miami River Basins declined as 

the percentage of urban land upstream 

of the sampling site increased. For 

example, concentrations of chloride in 

water samples were significantly higher 

with higher percentage of urban land 

use (p. 28), possibly in response to use of 

road salt during winter and the influence 

of urban wastewater and septic-tank 

discharges. Higher concentrations 

of insecticides, particularly those 

commonly used on lawns and 

commercial areas (such as diazinon), 

were detected in streams draining 

basins with higher percentages of urban 

land (fig. 31). As a result, the potential 

toxicity of pesticide mixtures to aquatic 

organisms increased rapidly at relatively 

low percentages of urban land cover (less 

than 10 percent) and then remained high, 

especially compared to the potential 

toxicity of herbicide-dominated mixtures 

found in agricultural streams. (See p. 9–

10, 28.) The number of pharmaceutical 

and household chemicals detected in 

streams—an indicator of the influence 

of urban wastewater discharges on water 

quality (p. 15–17)—was larger at higher 

percentages of urban land in the basin 

(fig. 31). In addition, the number of 

synthetic organic compounds detected in 

streambed sediment, such as polycyclic 

aromatic hydrocarbons (PAHs), increased 

as the percentage of urban land increased 

(fig. 32). 

Some wastewater discharges contribute excessive nutrient loads to stream 

systems; but concentrations of nitrate as 

nitrogen in the streams examined for this 

study actually decreased with increases 

in the percentage of urban land (p. 28). 

Although nitrogen-based fertilizers commonly are used on residential lawns and 

commercial areas, fertilizer applications 
26 Water Quality in the Great and Little Miami River Basins

on urban land appear to be less than those 

on farmland in basins with low urbanland percentages, at least on the basis of 

annual nutrient yields estimated for the 

urban stream Holes Creek (fig. 24, Reutter, 

2003). In cities where forested land is

developed for urban uses, however (for 

example, Boston; p. 28), nitrate concentrations in streams increased with the 

percentage of urban land. 

Aquatic-community reflects 

urban influences

Biological indicators of stream 

quality, such as the presence or absence 

of invertebrates, fish, and algae sensitive 

to contamination, commonly are used 

to assess the effects of urbanization on 

a stream. For example, data collected 

in four major metropolitan areas (p. 28) 

indicated that the numbers of pollutionsensitive aquatic insects—specifically, 

the numbers of mayfly, stonefly, and 

caddisfly taxa (orders Ephemeroptera, 

Plecoptera, and Trichoptera, or “EPT

richness”)—generally decreased as the 

percentage of urban land increased. Analyses of samples of aquatic organisms 

collected from the Dayton/Cincinnati 

area, however, indicated an initial decline 

of EPT richness in streams in basins with 

less than 15 percent urban land cover, an 

increase in EPT richness in streams in 

basins with urban land cover greater than 

15 percent, and considerable variability 

in EPT richness among streams draining 

predominantly agricultural land (that is, 

urban land cover less than 10 percent). 

The high degree of variability in EPT 

Figure 34. Increases in indicators 

of the effects of urban wastewater 

and runoff on water quality (number of 

household chemicals and pharmaceuticals) and sediment quality (number 

of metals with concentrations above a 

Threshold Effect Level) were associated 

with higher percentages of tolerant fish 

species and fewer diatom species. 

richness observed in the Dayton/Cincinnati streams may be partially attributable 

to variations in stream velocity: EPT 

richness increased significantly with 

stream velocity. Variations in stream 

velocity are related to minor differences 

in land-surface topography, channel 

slope, and other stream-habitat features 

in those basins. Of the streams examined 

in this study, higher stream velocities 

and associated favorable habitat features, 

such as riffles, were generally associated 

with streams draining more urbanized 

basins, hence greater EPT richness at 

some of the more urbanized sites.

Results from this and other 

NAWQA urban studies indicate that 

application of insecticides to lawns, 

homes, and commercial buildings in 

urban areas may also adversely affect 

aquatic-community structure, particularly 

benthic invertebrates (p. 28). EPT richness in Dayton/Cincinnati-area streams 

decreased significantly with increased 

Pesticide Toxicity Index (PTI) values 

(fig. 33). PTI values increased sharply 

in the 0- to 15-percent range of urban 

land cover and then remain relatively 

unchanged at moderate to high percentages of urban land (p. 28). Higher PTI 

values reflect the increased occurrence 

and higher concentrations of more toxic 

organophosphate insecticides, such as 

diazinon and chlorpyrifos, in urbanized 

stream basins. Improved aquatic-community structure in streams affected by 

urban development may be seen in the 

future as a result of the USEPA decision 

in 2000 to eliminate residential use of 

some of the more toxic organophosphate 

pesticides.

The relative abundance of pollutiontolerant fish in Dayton/Cincinnati area 

streams increased in concert with the 

number of household and pharmaceutical 

chemicals detected in water samples—an 

indicator of the influence of point-source 

discharges (fig. 34). Increases in pollutiontolerant organisms associated with 

wastewater discharges to streams have 

been well documented (Kemp and others, 

1967).

The number of diatom species 

declined with increases in the number of 

potentially toxic metals that were detected 

in streambed sediments at concentrations 

above a Threshold Effect Level (fig. 34; 

Box 3, p. 8). The metals of concern were 

arsenic, cadmium, chromium, copper, 

lead, and zinc. Diatoms are known to be 

sensitive to metal contamination (Austin 

and Deniseger, 1985), and these metals, 

individually or in combination, may be 

important in reducing diatom community 

richness. In urban environments, common sources of metals are treated wood 

products (arsenic, chromium, and copFigure 33. The number of sensitive 

invertebrate species (EPT; Ephemeroptera, Plecoptera, and Trichoptera) 

declined significantly as the Pesticide 

Toxicity Index (PTI) increased. 

Figure 32. The number of synthetic 

organic compounds detected in streambed sediments increased with urbanland percentage in the stream basin. 

NUMBER OF SYNTHETIC ORGANIC

COMPOUNDS IN STREAMBED SEDIMENT
Major Findings 27

Historically, 133 fish species representing 25 families have been 

documented in the Great and Little Miami River Basins. That number 

has declined over the last century, with 132 species reported since 

1901, 123 since 1955, 117 since 1980, and 113 post-1990 (Harrington, 

1999). Natural processes and human activities, especially channel 

modifications, wastewater discharges, and increased use of chemicals, 

have altered fish communities.

Fish communities may respond to environmental disturbances by 

changes in the population, including abundance, richness, and 

composition (Ohio Environmental Protection Agency, 1987). Index 

of Biotic Integrity components were divided into three groups (fish 

community composition, trophic composition, and fish condition), 

and representative components were calculated using available data 

in the Study Unit from 1900 through 1998. Although historically 

a decline in the total number of species has been documented, an 

increase in the number of native species from the 1955 to 1980 period 

to the 1980 to 1989 period indicates improvement in water quality. In 

the Little Miami River Basin, however, fish-community composition 

indicates continued stress as the percentages of carnivores, intolerant 

species, and lithophilic species, all indicators of good water quality, 

continued to decline through 1998. In the Great Miami River Basin, no 

consistent trend in composition was observed.

Changes observed in the Fish Community, 1900-98

Figure 35. Stream-habitat characteristics 

in urban areas (top) were generally better 

than those in more highly agricultural 

basins (bottom).

per), rubber tires (zinc), wheel weights 

(lead), brake pads (copper), and oil and 

grease additives (lead, nickel, and zinc). 

Although the presence of these metals at 

elevated levels in streambed sediments 

is usually attributed to urban sources, 

some metals may also be derived from 

natural sources, such as soils or eroded 

bedrock. For example, erosion of marineshale outcrops in the banks and bottom 

of streams draining the Kentucky River 

Basin yields sediment that commonly 

contains elevated concentrations of cadmium, lead, and zinc (Porter and others, 

1995). 

High-quality physical features—

forested ravines and steep channel 

slopes—in urban streams in the Great 

and Little Miami River Basin may help 

to explain somewhat anomalous trends 

in aquatic-community structure compared to NAWQA findings elsewhere. 

For example, sensitive EPT taxa did not 

continue to decline with increasing urban 

land as reported in other urban areas 

(p. 28) but rather began to increase in 

basins with greater than 15 percent 

urban land. Similarly, no significant 

trends with increasing urban land were 

found for Ohio’s fish-community-based 

IBI (Index of Biotic Integrity, p. 24) or 

benthic algal biomass (chlorophyll-a). In 

contrast to other urban areas studied by 

NAWQA, physical habitat along streams 

in the Dayton/Cincinnati areas is substantially more degraded in the least urbanized agricultural basins than in the more 

developed basins examined by this study. 

For example, physical features associated with the predominantly agricultural 

basins (little or no urban land) reflect 

poorly drained, flat land and streams with 

few riffles and relatively high percentages of fine clay substrate; together, these 

features make for unfavorable stream 

habitat (fig. 35).

In summary, results from NAWQA 

studies in urban areas across the Nation 

indicate that the condition of biological 

communities reflects a complex combination of factors associated with 

greater urban development, including 

degradation of water and sediment quality, stream habitat, and modification of 

streamflow and temperature (Couch and 

Hamilton, 2002). The relative association 

of these factors can also vary spatially 

and with seasonal and year-to-year differences in rainfall and runoff. Hence, 

results of these studies—which reflect 

summer low-flow conditions—may not 

be representative of seasonal or longterm variations. Nevertheless, improved 

understanding of how these factors vary 

in the Great and Little Miami River 

Basins along a gradient of urban land 

use will help to define the progression of 

stream degradation with respect to basin 

development. Furthermore, studies here 

and elsewhere in the Nation will identify 

settings where stream restoration and 

protection resources need to be focused 

and where water-quality management 

actions are likely to have the greatest 

benefits.
28 Water Quality in the Great and Little Miami River Basins

Urbanization can degrade water quality and affect 

sensitive aquatic life, according to a comparison of NAWQA 

findings among studies in the major metropolitan areas of 

Boston (New England Coastal Basins), Philadelphia (Delaware 

River Basin), Dayton and Cincinnati (Great and Little Miami 

River Basins), and Chicago (upper Illinois River Basin). These 

studies, which compared conditions among streams in basins 

ranging from minimally to highly urbanized, showed declines 

in indicators of biological-community health—and increases 

in chemical indicators of human activity—with increases in 

percentage of urban land. For example, the number of benthic 

invertebrate species sensitive to pollution, such as the “EPT 

insects” (mayflies [Ephemeroptera], stoneflies [Plecoptera], and 

caddisflies [Trichoptera]), generally decreased with increasing urban-land percentage in all four metropolitan areas. The 

declines in EPT insects were steepest from 0 to about 20 percent urban land, and with the exception of Dayton/Cincinnati, 

the decline continues with increased urbanization. The anomalous pattern in the Dayton/Cincinnati area may be associated, 

in part, with effects of high percentages of agricultural land 

in some of its less urbanized basins, as well as the absence of 

study sites with much more than 50 percent urban land.

Over space and time, invertebrate communities integrate 

the effects of many factors, including chemical changes, physical habitat alterations, and changes in types of food available 

to invertebrate consumers. Among the chemical changes noted 

with increasing urban land in the metropolitan areas studied 

were increased chloride concentrations and increased potential 

pesticide toxicity to benthic invertebrates. Chloride sources 

include municipal and industrial discharges, septic systems, 

and road-salt runoff. Other organic and inorganic chemicals 

may be associated with chloride from these sources. The potential toxicity of the mixture of pesticides detected in stream 

water increased with increasing urban land percentage, according to the Pesticide Toxicity Index (a measure for ranking sites 

based on summed concentrations of detected pesticides and 

the toxicity of each pesticide to benthic invertebrates [Munn 

and Gilliom, 2001]). The increase was especially pronounced 

at relatively low percentages of urban land. Contributing factors may include the amount, relative toxicity, and timing of 

pesticides—particularly insecticides—that are applied in urban 

settings.

Patterns of nitrate concentration with increasing urban 

land were not consistent among the four metropolitan areas. 

In fact, the only clear increase in nitrate concentrations with 

urbanization was in the Boston area. This is, in part, because 

nutrients in Boston-area streams are associated primarily with 

urban sources and are not affected by additional sources, such 

as fertilizers applied on agricultural land. Moreover, basins 

with minimal urban land in the Boston area are mainly forested, and nitrate concentrations in those streams are low (less 

than 0.1 mg/L). In contrast, nitrate concentrations in streams 

decreased with increasing urbanization in the Dayton/Cincinnati area and in minimally to moderately urban settings of the 

Chicago area, whereas in the Philadelphia area they neither 

increased nor decreased; fertilizers applied to crops contribute 

to the higher nitrate concentrations in some less urbanized 

basins in these settings. Sewage may be a factor contributing to 

the high nutrient concentrations in some highly urban Chicago 

streams.

In summary, biological and chemical characteristics in 

streams respond to increases in urban land in their respective 

basins. However, the responses may differ in pattern and in 

rate, so approaches for monitoring the effects of urbanization 

on streams may need to be tailored to specific metropolitan 

areas. Findings of these NAWQA studies may help in developing and prioritizing optimal management strategies for a 

particular setting.

NUMBER OF EPT

INVERTEBRATE TAXA,

IN PERCENTAGE OF

MAXIMUM BY

STUDY AREA

PERCENTAGE OF URBAN LAND

(LOWESS)

Selected examples of biological and chemical indicators in 

relation to urbanization. Smoothed lines are shown where 

the correlation (Spearman rank) between the biological or 

chemical factor and percentage of urban land is statistically 

significant at a probability value of less than 0.05.

Stream quality degrades as urbanization increases in 

four major metropolitan areas
Study Unit Design 29

Study Unit Design

Stream-chemistry studies were designed to measure how 

natural factors and human activities affect water quality (see 

p. 30):

• Eight drainage basins representing the dominant hydrologic

 and land-use settings in the Study Unit were selected for 

 the stream-chemistry network (four basic and four 

intensive sites). Seasonal variations in stream chemistry 

 were measured for a range of streamflows.

• Samples were collected at 30 sites in the Stillwater River 

 Basin after heavy spring rains to determine concentrations

 of chemicals in agricultural runoff. 

• During summer low-flow conditions, streamwater quality

 was assessed in 30 small stream basins with varying 

 amounts of agricultural and urban land in areas surrounding 

 Cincinnati and Dayton (“varied land-use” sites).

• Treated and untreated drinking-water samples were col-

 lected to assess pesticide concentrations in a water-supply

 reservoir (Harsha Lake).

Fish tissue and bed sediment were 

analyzed for environmental contaminants 

at each of the basic and intensive streamchemistry sites (eight sites total). Surveys 

of fish, benthic invertebrates, algae, and 

stream habitat were done one to four times 

to assess aquatic-community status. Multiple-reach surveys were done at two sites; 

reaches ranged from 655 to 1,640 feet in 

length. Periphyton, phytoplankton, chlorophyll, and streambed-sediment samples were collected 

to compare concentrations of nutrients, algae, and selected 

organic contaminants in 30 small stream basins with varying amounts of agricultural and urban land. Water, streambed sediment, and sport fish fillet samples were analyzed for 

mercury and methylmercury at eight stream-chemistry sites.

Ground-water studies focused exclusively on sand-andgravel deposits, known as the buried-valley aquifer system, 

a major source of drinking water aquifer in the Study Unit. 

(See p. 30.) Ground-water studies were designed to measure 

water quality in the following:

• Domestic wells screened at various depths in the aquifer 

• High-capacity public-supply wells next to large streams 

• Shallow ground water in areas overlain by agricultural or

 urban land use (monitoring wells)

• Tile drains beneath croplands to assess the quality of infil-

 trating soil water.

EXPLANATION

Basic site (4)

Intensive site (4)

Agricultural runoff site (30)

Varied land-use site (30)

Pesticide reservoir site (4)

Single reach-single year (5)

Single reach-multiyear (1)

Multi-reach-multiyear (2)

Mercury study site (8)

Urban

Agriculture

Forest

Water

MILES

KILOMETERS

Public-supply well (15)

Domestic well (30)

Agricultural land-use well (34)

Urban land-use well (25)

Tile drain site (4)

(Sand and gravel)

MILES

KILOMETERS

EXPLANATION

Urban land use

Till plains

Between glacial lobes

Drift plains/unglaciated

Outwash deposits

Site

number Site name Setting Basin area(squaremiles)

Site

number Site name Setting Basin area(square miles)

1 East Fork Little Miami River

near Williamsburg, Ohio

Cropland/

Drift Plains

234 5 Holes Creek near

Kettering, Ohio

Urban/

Till Plains

20.0

Little Miami River

near Milford, Ohio

Mixed land use/

Till-Drift Plains

1,203 6 Stillwater River near

Union, Ohio

Cropland/

Till Plains

646

3 Great Miami River

at Hamilton, Ohio

Mixed land use/

Till Plains

3,630 7 Great Miami River

near Vandalia, Ohio

Cropland/

Till Plains

1,142

4 Whitewater River near

Alpine, Indiana

Cropland/

Interlobate

529 8 Mad River near

Eagle City, Ohio

Cropland/

Interlobate

310

2
30 Water Quality in the Great and Little Miami River Basins

1

SUMMARY OF DATA COLLECTION IN THE GREAT AND LITTLE MIAMI RIVER BASINS, 1998-2001

Study

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

Sampling frequency and

period

Stream and Lake Chemistry

Basic

sites

Streamflow, nutrients, major ions, bacteria, organic carbon,

suspended sediment, and physical parameters. To determine

how often and how much of a constituent is present, over

time, in response to different seasonal or land-use patterns.

Sites were selected to represent the range

of hydrologic and land-use settings in

the Study Unit, including basin outflow

sites.

4

Monthly; storm and lowflow events, for two

years (October 1998-

September 2000)

Intensive

sites

Same as above plus VOCs, pesticides, and pesticide degradates.

VOCs sampled at urban and large-river sites only. To determine

how often and how much of a chemical is present, over time,

in response to different seasonal or land-use patterns.

Includes small urban basin (Holes Creek),

two larger row-crop agricultural basins

(Mad River, East Fork Little Miami

River), and large river, mixed-land-use

site (Great Miami River at Hamilton).

4

Weekly to monthly; storm

and low-flow events for

2 years, three sites sampled monthly for third

year

Special Studies

Agriculturalrunoff

sites

Streamflow, physical properties, nutrients, major ions, bacteria,

organic carbon, suspended sediment, pesticides, nitrogen isotopes, and antibiotics. To evaluate concentrations and sources

of agrichemicals in streams during a rainfall and runoff

event.

30 streams draining agricultural basins

ranging in size from 1.5 to 609 square

miles with varying amounts of animal

production intensity in the Stillwater

River Basin.

30

Once following heavy

rains May 19-20, 2000.

Biweekly samples at

basin outlet MarchSeptember 2000

Variedland-use

streams

Streamflow, physical properties, major ions, nutrients, organic

carbon, bacteria, suspended sediment, pesticides, and household

chemicals and pharmaceuticals. To evaluate stream quality

with varying amounts of agricultural and urban land.

30 streams draining basins ranging in size

from 2.8 to 65 square miles with varying amounts of agricultural and urban

land.

30 Once in July 2001

Reservoir

pesticide

study

Physical properties, pesticides, and pesticide degradates. To

provide information on pesticide concentrations in treated

and untreated drinking water withdrawn from supply reservoirs across the Nation.

2 stream sites representing major inflow

and reservoir outflow sites; 1 treated

and 1 untreated drinking-water site at

East Fork Lake reservoir (Harsha Lake).

4

Quarterly throughout year

except biweekly during

spring-summer months,

1999-2000

Stream Ecology, Fish Tissue, and Streambed Sediment

Stream ecology

Algal, benthic-invertebrate, and fish communities and the condition

of stream habitat. To determine the effects of water quality and

habitat on aquatic biota.

Sites collocated at or near basic and intensive stream sites. 8One to four times September 1998-August 2001

Streambed

sediment and

fish tissue

Organochlorine pesticides and semivolatile organic compounds in

sieved sediment and whole fish (common carp). Trace elements

in sieved sediment and carp livers. To measure how much the

occurence of a chemical changes because of different land- or

chemical-use patterns.

Sites collocated at or near basic and intensive stream sites.

8 Once in September 1998

Varied land- use streams

Aquatic

biota

Algal (periphyton and phytoplankton) communities and the condition of stream habitat. To evaluate response of aquatic biota

with varying amounts of agricultural and urban land.

Sites collocated with varied-land-use

stream sites. 30

One to four times in September 1998-August

2001

Streambed

sediment

Organochlorine pesticides, semivolatile organic compounds, and

trace elements in sieved sediment. To evaluate streambed sediment chemistry with varying amounts of agricultural and

urban land.

Sites collocated with varied-land-use

stream sites. 30 Once in July 2001

Special study:

mercury in water,

sediment, and fish

tissue

Mercury and methylmercury in water column, streambed sediment,

and sport fish (smallmouth bass) fillets. To evaluate factors for

mercury occurrence and the potential for mercury methylation across the Nation.

Sites collocated at or near basic and intensive stream sites; part of larger national

mercury study. 8 Once in September 1998

Ground-Water Chemisty

Existing wells

Domesticwell

study

Water-level, physical properties, nutrients, major ions, bacteria,

organic carbon, trace elements, pesticides, pesticide degradates,

VOCs, tritium and helium isotopes. To evaluate quality of

ground water withdrawn for domestic use from the buriedvalley aquifer system.

29 domestic and 1 supply well screened at

varying depths in the buried-valley

aquifer system throughout the Study

Unit.

30 Once in May-July 1999

Publicsupplywell

study

Same as domestic-well study above except tritium and helium

isotopes were not collected. To evaluate quality of ground

water pumped from high-capacity public-supply wells

located adjacent to large streams.

Public-supply wells adjacent to streams in

the buried-valley aquifer system

throughout the Great Miami River

drainage basin.

15 Once in May-June 1999

Monitoring wells

Agriculturalland-use

study

Same as domestic-well study except bacteria and VOCs were not

collected. To evaluate effects of row-crop agriculture on

shallow ground-water quality.

Installed 26 shallow monitoring wells in

areas where the buried-valley aquifer

system is overlain by row-crop agriculture. At 8 sites, intermediate depth

monitoring wells were also installed.

34 total

26 shallow

Once in July-August 2000

Urban

land-use

study

Same as domestic-well study except bacteria, pesticide degradates,

tritium and helium isotopes were not sampled. Selected household chemicals and pharmaceuticals, and sulfur hexafluoride also

were collected. To evaluate effects of residential-commercial

development on shallow ground-water quality.

Installed 25 shallow monitoring wells in

areas where the buried-valley aquifer

system is overlain by residentialcommercial areas developed in the last

30-40 years.

25 Once in OctoberDecember 2001

Tiledrain

study

Physical properties, discharge, nutrients, seleced pesticides, and

pesticide degradates. To assess occurrence of nutrients,

pesticides, and pesticide degradates in tile drainage.

4 tile drains beneath corn and soybean

fields in Darke County, Ohio. Part of

regional assessment of tile-drain water

quality across the Midwest.

4

Three times (pre-plant,

post-plant, post-harvest)

spring-fall 2001.
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Glossary 33

Glossary

Abundance Number of individuals in a community, habitat, or 

sample.

Animal Unit (AU) The number of animals of various sizes and 

species which are equivalent to one slaughter or feeder beef 

with regard to daily waste production; thus, 1 AU is equivalent 

to 1 slaughter or beef cattle, 0.7 mature dairy cow, 0.5 horse, 

2.5 swine weighing more than 25 kilograms, and 100 laying 

hens.

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

will yield usable quantities of water to a well. 

Base flow Sustained, low flow in a stream; ground-water discharge is the source of base flow in most places. 

Basic Fixed Sites Sites on streams at which streamflow is 

measured and samples are collected for temperature, salinity, suspended sediment, major ions and metals, nutrients, and 

organic carbon to assess the broad-scale spatial and temporal 

character and transport of inorganic constituents of streamwater 

in relation to hydrologic conditions and environmental settings.

Benthic Refers to plants or animals that live on the bottom of 

lakes, streams, or oceans. 

Bioaccumulation The net accumulation of a substance by an 

organism as a result of uptake from all environmental sources, 

including gills, epithelial tissues, and dietary sources.

Breakdown products See Degradate. 

Carnivore Flesh-eating organism.

Community In ecology, the species that interact in a common 

area. 

Composition General makeup of the species present in a community, along with a measure of their relative abundance.

Concentration The amount or mass of a substance present in a 

given volume or mass of sample. Usually expressed as micrograms per liter (μg/L) or milligrams per liter (mg/L) for water 

samples or micrograms per kilogram (μg/kg) or micrograms per 

gram (μg/g) for sediment or tissue samples. Radon is reported 

in picocuries per liter (pCi/L). Periphyton organisms, which 

attach to rocks and other structures, are measured in mass per 

area, such as milligrams per square meter (mg/m2).

Degradate A compound derived by chemical, biological, or 

physical action upon a organic substance. The breakdown is a 

natural process that may result in a more toxic or a less toxic 

compound and a more persistent or less persistent compound. 

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. 

Diatoms Single-celled, colonial, or filamentous algae with 

siliceous cell walls constructed of two overlapping parts.

Domestic well A private home well, or a well that serves fewer 

than 15 households or 25 individuals. 

EPT Organisms in three insect orders —mayflies (Ephemeroptera), stoneflies (Plecoptera), and caddisflies (Trichoptera)— that are composed primarily of species considered to 

be relatively intolerant to environmental alterations. 

Endocrine system The collection of glands in animals that 

secrete hormones, which influence growth, gender, and sexual 

maturity. 

Eutrophication The process by which water becomes enriched 

with plant nutrients, most commonly phosphorus and nitrogen.

Fertilizer Any of a large number of natural or synthetic materials, including manure, and nitrogen, phosphorus, and potassium compounds, spread or worked into soil to increase its 

fertility. 

Flow-weighted mean A concentration calculated by first multiplying each sample concentration by its associated streamflow 

value, then dividing the sum of these products by the sum of 

the streamflows. The resultant mean value accounts for the 

effects of variable streamflow on concentrations.

Fungicide A chemical or other agent applied for the purpose of 

killing undesirable fungi. See also Pesticide.

Herbicide A chemical or other agent applied for the purpose of 

killing undesirable plants. See also Pesticide.

Index of Biotic Integrity (IBI) An aggregated number, or 

index, based on several attributes or metrics of a fish community that provides an assessment of biological conditions. 

Insecticide A substance or mixture of substances intended to 

kill or repel insects. See also Pesticide.

Intensive Fixed Sites Basic Fixed Sites with increased sampling frequency during selected seasonal periods and analysis 

of dissolved pesticides for 1 year. Most NAWQA Study Units 

have one to two integrator Intensive Fixed Sites and one to 

four indicator Intensive Fixed Sites.

Intolerant species Organisms that are not adaptable to human 

alterations to the environment and thus decline in numbers 

where human alterations occur. See also Tolerant species. 

Invertebrate An animal having no backbone or spinal column.

Lithophilic Refers to fish that exhibit simple spawning 

behavior and require clean gravel and (or) cobble substrates 

for successful reproduction.
34 Water Quality in the Great and Little Miami River Basins

Load General term that refers to a material or constituent in 

solution, in suspension, or in transport; usually expressed in 

terms of mass or volume.

LOWESS smooth LOcally WEighted Scatterplot Smoothing, 

a statistical method of defining a smooth curve through the 

middle of a scatterplot to highlight trends or patterns in the 

data. 

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. 

Metabolite See Degradate. 

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. In this 

report, the term “nitrate” is used as shorthand for “nitrate plus 

nitrite, reported as nitrogen.”

Nonpoint source A pollution source that cannot be defined as 

originating from a discrete point such as a pipe discharge. 

Nutrient Element or compound essential for animal and plant 

growth. Common nutrients in fertilizer include nitrogen, phosphorus, and potassium. 

Organochlorine insecticide A class of organic insecticides 

containing a high percentage of chlorine. Includes dichlorodiphenylethanes (such as DDT), chlorinated cyclodienes (such 

as chlordane), and chlorinated benzenes (such as lindane). 

Most organochlorine insecticides were banned because of their 

carcinogenicity, tendency to bioaccumulate, and toxicity to 

wildlife. 

Outwash Sediment deposited by streams fed by glacial meltwater.

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. 

Point source A pollution source at a discrete location such 

as discharge pipe, drainage ditch, tunnel, well, concentrated 

livestock operation, or floating craft.

Polychlorinated biphenyls (PCBs) A mixture of chlorinated 

derivatives of biphenyl, marketed under the trade name Aroclor with a number designating the chlorine content (such as 

Aroclor 1260). PCBs were used in transformers and capacitors 

for insulating purposes and in gas pipeline systems as a lubricant. Further sale for new use was banned by law in 1979. 

Polycyclic aromatic hydrocarbon (PAHs) A class of organic 

compounds with a fused-ring aromatic structure. PAHs result 

from incomplete combustion of organic carbon (including 

wood), municipal solid waste, and fossil fuels. PAHs include 

benzo[a]pyrene, fluoranthene, and pyrene. 

Recharge Water that infiltrates the ground and reaches the 

saturated zone. 

Richness Number of species in a community, habitat, or 

sample.

Runoff Rainwater or snowmelt that is transported to streams 

by overland flow, tile drains, or ground water. 

Semivolatile organic compound (SVOC) Operationally 

defined as a group of synthetic organic compounds that 

are solvent extractable and can be determined by gas 

chromatography/mass spectrometry. SVOCs include phenols, 

phthalates, and polycyclic aromatic hydrocarbons (PAHs). 

Streambed sediment The material that temporarily is stationary on the bottom of a stream or other watercourse. 

Taxon (plural taxa) Any identifiable group of taxonomically 

related organisms. 

Tile drain A buried perforated pipe designed to remove excess 

water from soils. 

Till Unconsolidated sediment that contains a mixture of clay to 

boulder-sized particles, deposited by advancing and retreating 

glaciers.

Tolerant species Those species that are adaptable to (tolerant 

of) human alterations to the environment and often increase in 

number when human alterations occur.

Trophic A level in the food pyramid.

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 by-products of chlorine 

disinfection. 

Water table The point below the land surface at which 

ground water is first encountered and below which the earth 

is saturated. Depth to the water table varies widely across the 

country. 

Yield With reference to water quality, the mass of material or 

constituent transported by river in a specified period of time 

divided by the drainage area of the river basin.
Appendix—Water-Quality Data from the Great and Little Miami 

River Basins in a National Context

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36 Water Quality in the Great and Little Miami River Basins

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Coordination with agencies and organizations in the Great and Little Miami River Basins was integral 

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

liaison committee. 

Federal Agencies

U.S. Army Corps of Engineers 

U.S. Department of Agriculture

U.S. Environmental Protection Agency

State Agencies

Ohio Department of Natural Resources

Ohio Environmental Protection Agency

Indiana Department of Environmental 

 Management

Indiana Department of Natural

 Resources

Local Agencies

Butler County Department of 

 Environmental Services

City of Cincinnati

City of Dayton

City of Fairfield

City of Hamilton

Clermont County Office of Environmental 

 Quality

Ohio State University Extension South 

 west District

Hamilton County Health District

Hamilton to New Baltimore Ground 

 Water Consortium

Miami Conservancy District

Miami Valley Regional Planning 

 Commission

Ohio-Kentucky-Indiana Regional Council 

 of Governments

Universities

Earlham College

Heidelburg College

Miami University

University of Cincinnati

University of Dayton

Wright State University

Other public and private organizations

Dayton Power and Light

Little Miami Incorporated

Mill Creek Watershed Project

Ohio Farm Bureau Federation

Procter and Gamble Corporation

Stillwater Watershed Council

Terran Corporation

We thank the following individuals for contributing to this effort. 

Michael Ekberg, Miami Conservancy District

Robert Miltner and Jeffrey DeShon, Ohio Environmental Protection Agency

Eric Heiser, Clermont County Water and Sewer Service

Special thanks to U.S. Geological Survey employees for their contributions:

Dennis Finnegan, lead technician, Rhett Moore, Linda Debrewer, Lori Mattern, Kevin Metzker, Jason Funk, Dustin Reed, 

Laura Simonson, Robert Darner, Steven Fuller, Brian Mailot, Jonathan Lageman, Thomas Schumann, Alan Dillenburg, Karen 

Bossenbroek, James Rauman, Drew McGowan, Brent Means, Jeffrey Frey, Shawn Alexander Covert, Amie Brady, Emma 

Granger, Jocelyn Hach; and C. Michael Eberle for editing this report.

Appreciation is also extended to those individuals and agencies that reviewed this report: 

Donna Myers, Mark Ayers, Michael Yurewicz, Martin Gurtz, Pixie Hamilton, Martha Erwin, Chester Zenone, and others at the 

U.S. Geological Survey; Anne Baird, Ohio State University Extension, Southwest District; Richard Bendula, Robert Miltner, James 

Simpson, Diana Zimmerman, Ohio Environmental Protection Agency; Michael Ekberg and Dusty Hall, Miami Conservancy District; 

Larry Antosch, Ohio Farm Bureau Federation; and Jane Wittke, Ohio-Kentucky-Indiana Regional Council of Governments.
Rowe and others— Water Quality in the Great and Little Miami River Basins

U.S. Geological Survey Circular 1229

National Water-Quality Assessment (NAWQA) Program

Great and Little Miami River Basins

NAWQA

Springfield

Cincinnati

Dayton

Hamilton

Richmond