The authors appreciate the extraordinary efforts of the editorial and cartography staff of the Georgia District, 

including Caryl J. Wipperfurth, Carolyn A. Casteel, Willis G. Hester, and Eric A. Steinnagel.

Cover photographs: (1) interior of a chicken house in northern Georgia; (2) application of farm chemicals, 

(3) skyline of Metropolitan Atlanta, Georgia; (4) a wastewater-treatment facility on the Chattahoochee River, 

Atlanta, Georgia; and (5) sediment discharging from the mouth of Suwanee Creek into the

Chattahoochee River near Atlanta, Georgia.
NUTRIENT SOURCES AND ANALYSIS OF NUTRIENT 

WATER-QUALITY DATA, APALACHICOLA–

CHATTAHOOCHEE–FLINT RIVER BASIN, GEORGIA, 

ALABAMA, AND FLORIDA, 1972–90

By Elizabeth A. Frick, Gary R. Buell, and Evelyn E. Hopkins 

__________________________________________________________________

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 96-4101

National Water-Quality Assessment Program

Atlanta, Georgia

1996
U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Gordon P. Eaton, Director

Any use of firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government

_____________________________________________________________________________________________

For further information, write to

District Chief

U.S. Geological Survey

3039 Amwiler Road, Suite 130

Atlanta, GA 30360-2824

Copies of this report can be purchased from

U.S. Geological Survey

Branch of Information Service

Denver Federal Center

Box 25286

Denver, CO 80225-0286
iii

FOREWORD

The mission of the U.S. Geological Survey (USGS) is to assess the quantity and quality of the earth resources 

of the Nation and to provide information that will assist resource managers and policymakers at Federal, State, and 

local levels in making sound decisions. Assessment of water-quality conditions and trends is an important part of 

this overall mission.

One of the greatest challenges faced by water-resources scientists is acquiring reliable information that will 

guide the use and protection of the Nation's water resources. That challenge is being addressed by Federal, State, 

interstate, and local water-resource agencies and by many academic institutions. These organizations are collecting 

water-quality data for a host of purposes that include: compliance with permits and water-supply standards; 

development of remediation plans for a specific contamination problem; operational decisions on industrial, 

wastewater, or water-supply facilities; and research on factors that affect water quality. An additional need for 

water-quality information is to provide a basis on which regional and national-level policy decisions can be based. 

Wise decisions must be based on sound information. As a society, we need to know whether certain types of waterquality problems are isolated or ubiquitous, whether there are significant differences in conditions among regions, 

whether the conditions are changing over time, and why these conditions change from place to place and over time. 

The information can be used to help determine the efficacy of existing water-quality policies and to help analysts 

determine the need for, and likely consequences, of new policies.

To address these needs, the Congress appropriated funds in 1986 for the USGS to begin a pilot program in 

seven project areas to develop and refine the National Water-Quality Assessment (NAWQA) Program. In 1991, the 

USGS began full implementation of the program. The NAWQA Program builds upon an existing base of waterquality studies of the USGS, as well as those of other Federal, State, and local agencies. The objectives of the 

NAWQA Program are to:

 • describe current water-quality conditions for a large part of the Nation's freshwater streams, rivers, 

and aquifers;

 • describe how water quality is changing over time; and

 • improve understanding of primary natural and human factors that affect water-quality conditions.

This information will help support the development and evaluation of management, regulatory, and monitoring 

decisions by other Federal, State, and local agencies to protect, use, and enhance water resources.

The goals of the NAWQA Program are being achieved through ongoing and proposed investigations of 60 of 

the Nation's most important river basins and aquifer systems, which are referred to as study units. These study units 

are distributed throughout the Nation and cover a diversity of hydrogeologic settings. More than two-thirds of the 

Nation's freshwater use occurs within the 60 study units and more than two-thirds of the people served by public 

water-supply systems live within their boundaries.

National synthesis of data analysis, based on aggregation of comparable information obtained from the study 

units, is a major component of the program. This effort focuses on selected water-quality topics using nationally 

consistent information. Comparative studies will explain differences and similarities in observed water-quality 

conditions among study areas and will identify changes and trends and their causes. The first topics addressed by the 

national synthesis are pesticides, nutrients, volatile organic compounds, and aquatic biology. Discussions on these 

and other water-quality topics will be published in periodic summaries of the quality of the Nation's ground and 

surface water as the information becomes available.

This report is an element of the comprehensive body of information developed as part of the NAWQA 

Program. The program depends heavily on the advice, cooperation, and information from many Federal, State, 

interstate, Tribal, and local agencies and the public. The assistance and suggestions of all are greatly appreciated. 

Information regarding the NAWQA Program is available on the Internet via the World Wide Web. You may 

connect to the NAWQA Home Page using the Universal Resources Locator (URL) at:

<URL:http://wwwrvares.er.usgs.gov/nawqa/nawqa_home.html>
iv

CONTENTS

Abstract 1

Introduction 2

Purpose and scope 3

Description of Apalachicola–Chattahoochee–Flint River basin 3

Location and physiography 3

Climate and hydrologic setting 3

Population, land use, and water use 6

Acknowledgments 12

Nutrient sources 12

Point-source loads 12

Municipal-wastewater effluent 15

Nonpoint-source inputs 22

Animal manure 23

Fertilizer 23

Atmospheric deposition 25

Analysis of nutrient water-quality data 27

Nutrient water-quality standards, health advisories, and criteria 27

Sources of nutrient water-quality data 28

Assessment approach 28

Data compilation and screening 29

Distribution of sampling sites 29

Nutrients in surface water 35

Relation of concentration to stream discharge 41

Downstream variations in concentrations 56

Seasonal variations in concentrations 70

Temporal trends in concentrations 78

Annual loads and mean annual yields 90

Nutrients in ground water 96

Nitrate concentrations 98

Nutrient distributions by aquifer and well depth 99

Nutrient distributions by water-use category 101

Summary 104

References 107
v

ILLUSTRATIONS

Figures 1-3. Maps showing:

 1. Location of the Apalachicola-Chattahoochee-Flint River basin including physiographic provinces 4

 2. Location of subbasins and corresponding hydrologic unit codes, Apalachicola–Chattahoochee–Flint 

River basin 5

 3. Generalized outcrop areas for geologic and hydrogeologic units underlying the 

Apalachicola–Chattahoochee–Flint River basin 7

Figure 4. Chart showing generalized geologic and hydrogeologic units in the Coastal Plain of the ApalachicolaChattahoochee–Flint River basin 8

Figures 5-6. Maps showing:

 5. Land use, Apalachicola–Chattahoochee–Flint River basin 11

 6. Location of municipal-wastewater outfalls having discharges greater than one million gallons per day, 

Apalachicola–Chattahoochee–Flint River basin, 1990 20

Figures 7-8. Graphs showing:

 7. Effluent discharge from ten municipal-wastewater-treatment facilities that discharge more than 1 

million gallons per day into the Chattahoochee River and its tributaries and population of the five 

counties where these facilities discharge, Metropolitan Atlanta, 1980–95 21

 8. Effluent discharge and ammonia and phosphorus loads from the six largest municipal-wastewatertreatment facilities, Middle Chattahoochee–Lake Harding subbasin, 1980–93 22

Figures 9-11. Maps showing:

 9. Nitrogen and phosphorus inputs from animal manure, by county, Apalachicola–Chattahoochee–Flint 

River basin, 1990 24

10. Nitrogen and phosphorus inputs from fertilizer, by county, Apalachicola–Chattahoochee–Flint River 

basin, 1990 26

11. Location of National Atmospheric Deposition Program precipitation stations used to estimate 

nitrogen input from atmospheric deposition within the Apalachicola–Chattahoochee–Flint 

River basin 27

Figure 12. Graphs showing number of nutrient water-quality samples analyzed from streams, reservoirs and lakes, 

wells, and springs, Apalachicola–Chattahoochee–Flint River basin, 1972–90 water years 35

Figures 13-14. Maps showing:

13. Distribution of stream, reservoir, and lake water-sampling sites having nutrient data, by collection 

agency, Apalachicola–Chattahoochee–Flint River basin, 1972–90 water years 36

14. Distribution of ground-water sampling sites having nutrient data, by collection agency, Apalachicola–

Chattahoochee–Flint River basin, 1972–90 water years 38

Figure 15. Graphs showing distribution of nutrient concentrations in (A) streams and (B) reservoirs and lakes by 

nutrient-constituent groups, Apalachicola–Chattahoochee–Flint River basin, 1972–90

water years 41

16. Map showing locations of surface-water sites where data were used in nutrient analyses, Apalachicola–

Chattahoochee–Flint River basin, 1990 50

Figures 17-35. Graphs showing:

17. Distribution of nutrient samples within decile-flow classes for nine stream-sampling sites, 

Apalachicola–Chattahoochee–Flint River basin, 1972–90 water years 52

18. Relation between dissolved-ammonia concentration and discharge for two mainstem and four 

tributary sampling sites, Apalachicola–Chattahoochee–Flint River basin, 1972–90 water years 53

19. Relation between dissolved-nitrate concentration and discharge for two mainstem and four tributary 

sampling sites, Apalachicola–Chattahoochee–Flint River basin, 1972–90 water years 54

20. Relation between total-phosphorus concentration and discharge for two mainstem and four tributary 

sampling sites, Apalachicola–Chattahoochee–Flint River basin, 1972–90 water years 55

21. Instantaneous discharge when nutrient samples were collected in (A) Chattahoochee and 

Apalachicola, and (B) Flint and Apalachicola River basins, 1972–90 water years 57

22. Downstream variation in total-nitrogen concentrations in (A) Chattahoochee and Apalachicola, and 

(B) Flint and Apalachicola River basins, 1972–90 water years 58
vi

ILLUSTRATIONS—Continued

Figures 17-35. Graphs showing:—Continued

23. Downstream variation in total-inorganic-nitrogen concentrations in (A) Chattahoochee and 

Apalachicola, and (B) Flint and Apalachicola River basins, 1972–90 water years 59

24. Downstream variation in total-organic-nitrogen concentrations in (A) Chattahoochee and 

Apalachicola, and (B) Flint and Apalachicola River basins, 1972–90 water years 60

25. Downstream variation in dissolved-ammonia concentrations in (A) Chattahoochee and Apalachicola, 

and (B) Flint and Apalachicola River basins, 1972–90 water years 61

26. Downstream variation in dissolved-nitrate concentrations in (A) Chattahoochee and Apalachicola, 

and (B) Flint and Apalachicola River basins, 1972–90 water years 62

27. Downstream variation in dissolved-organic-nitrogen concentrations in (A) Chattahoochee and 

Apalachicola, and (B) Flint and Apalachicola River basins, 1972–90 water years 63

28. Downstream variation in total-phosphorus concentrations in (A) Chattahoochee and Apalachicola, 

and (B) Flint and Apalachicola River basins, 1972–90 water years 64

29. Downstream variation in dissolved-orthophosphate concentrations in (A) Chattahoochee and 

Apalachicola, and (B) Flint and Apalachicola River basins, 1972–90 water years 65

30. Seasonal variation in dissolved-ammonia concentrations for selected streams and reservoirs, 

Chattahoochee River, 1972–90 water years 72

31. Seasonal variation in dissolved-nitrate concentrations for selected streams and reservoirs, 

Chattahoochee River, 1972–90 water years 73

32. Seasonal variation in total-phosphorous concentrations for selected streams and reservoirs, 

Chattahoochee River, 1972–90 water years 74

33. Seasonal variation in dissolved-ammonia concentrations for selected streams and reservoirs, Flint, 

Chipola, and Apalachicola Rivers, 1972–90 water years 75

34. Seasonal variation in dissolved-nitrate concentrations for selected streams and reservoirs, Flint, 

Chipola, and Apalachicola Rivers, 1972–90 water years 76

35. Seasonal variation in total-phosphorous concentrations for selected streams and reservoirs, Flint, 

Chipola, and Apalachicola Rivers, 1972–90 water years 77

Figure 36. Map showing summary of trends for concentration of dissolved ammonia, dissolved nitrate, and total 

phosphorus in surface water, Apalachicola–Chattahoochee–Flint River basin, 1980–90 water 

years 82

Figures 37-47. Graphs showing:

37. Temporal variation in dissolved-ammonia concentrations for selected streams and reservoirs and 

1980–90 trend, Chattahoochee River, 1972–90 water years 84

38. Temporal variation in dissolved-nitrate concentrations for selected streams and reservoirs, and 

1980–90 trend, Chattahoochee River, 1972–90 water years 85

39. Temporal variation in total-phosphorous concentrations for selected streams and reservoirs and 

1980–90 trend, Chattahoochee River, 1972–90 water years 86

40. Temporal variation in dissolved-ammonia concentrations for selected streams and reservoirs and 

1980–90 trend, Flint, Chipola, and Apalachicola Rivers, 1972–90 water years 87

41. Temporal variation in dissolved-nitrate concentrations for selected streams and reservoirs and 

1980–90 trend, Flint, Chipola, and Apalachicola Rivers, 1972–90 water years 88

42. Temporal variation in total-phosphorous concentrations for selected streams and reservoirs and 

1980–90 trend, Flint, Chipola, and Apalachicola Rivers, 1972–90 water years 89

43. Annual loads of dissolved ammonia, dissolved nitrate, and total phosphorus and mean annual 

discharge for eight stream-sampling sites, Apalachicola–Chattahoochee–Flint River basin, 

1972–90 water years 91

44. Nitrogen loads at selected sites along the Apalachicola, Chattahoochee, and Flint Rivers, 

1989 and 1990 water years 93

45. Total-phosphorus loads at selected sites along the Apalachicola, Chattahoochee, and Flint Rivers, 

1989 and 1990 water years 94

46. Nitrogen and total-phosphorous sources to and output from the Apalachicola–Chattahoochee–Flint 

River basin, 1990 95
vii

ILLUSTRATIONS—Continued

Figures 37-47. Graphs showing:—Continued

47. Distribution of nutrient concentrations in (A) wells and (B) springs by nutrient-constituent groups, 

Apalachicola–Chattahoochee–Flint River basin, 1972–90 water years 97

Figure 48. Map showing location of ground-water-sampling sites with nutrient data, by aquifer and well depth, 

Apalachicola–Chattahoochee–Flint River basin, 1972–90 water years 100

Figures 49-50. Graphs showing:

49. Distribution by aquifer of dissolved-ammonia, dissolved-nitrate, and total-phosphorous concentrations 

in wells, Apalachicola–Chattahoochee–Flint River basin, 1972–90 water years 102

50. Distribution by water-use category of dissolved-ammonia, dissolved-nitrate, and total-phosphorous 

concentrations in wells, Apalachicola–Chattahoochee–Flint River basin, 

1972–90 water years 103

TABLES

Table 1. Population distribution, by subbasin, Apalachicola–Chattahoochee–Flint River basin, 1970, 1980,

and 1990 9

2. Land-use and land-cover distributions, by subbasin, Apalachicola-Chattahoochee-Flint River 

basin 10

3. Water withdrawals by principal water-use categories, by subbasin, Apalachicola–Chattahoochee–Flint 

River basin, 1990 13

4. Point-source loads and nonpoint-source inputs of nutrients, by subbasin, Apalachicola–Chattahoochee–

Flint River basin, 1990 14

5. Municipal wastewater discharges, by subbasin, Apalachicola–Chattahoochee–Flint River basin, 

1990 16

6. Nutrient loads from municipal wastewater facilities discharging more than one million gallons per day, by 

subbasin, Apalachicola–Chattahoochee–Flint River basin, 1990 17

7. Summary of algorithms used to transform source data collected in the Apalachicola–Chattahoochee–Flint 

River basin into selected nutrient constituent groups 30

8. Compilation of the number of sites and nutrient analyses from Federal and State sources of digital data, by 

media type, Apalachicola–Chattahoochee–Flint River basin, 1972–90 

water years 33

9. Summary of graphical and statistical analyses of nutrient data, by media type, Apalachicola–

Chattahoochee–Flint River basin, 1972–90 water years 39

10. Streamflow and basin characteristics for surface-water sites where data were used in nutrient analyses, by 

subbasin, Apalachicola–Chattahoochee–Flint River basin, 1990 42

11. Comparison of nutrient concentrations at sampling sites upstream and downstream of major cities, 

Apalachicola–Chattahoochee–Flint River basin, 1972–90 water years 66

12. Comparison of nutrient concentrations at sampling sites in river reaches downstream of major municipal 

point-source inputs, Apalachicola–Chattahoochee–Flint River basin, 1972–90 water years 67

13. Comparison of nutrient concentrations at sampling sites in and downstream of reservoirs, ApalachicolaChattahoochee-Flint River basin, 1972–90 water years 69

14. Land use and land cover, median nutrient concentrations, and mean annual yield for eight tributary 

streams, Apalachicola–Chattahoochee–Flint River basin, 1972–90 water years 71

15. Trend-test results for nutrient concentrations for selected surface-water sampling sites, by subbasin, 

Apalachicola–Chattahoochee–Flint River basin, 1980–90 water years 79

16. Mean annual loads and yields for nutrients for selected surface-water sampling sites, by nutrient 

constituent group, Apalachicola–Chattahoochee–Flint River basin, 1972–90 water years 112
viii

CONVERSION FACTORS AND 

ACRONYMS AND ABBREVIATIONS

CONVERSION FACTORS

Multiply by to obtain

Length

inch (in.) 25.4 millimeter

mile (mi) 1.609 kilometer

Area

square mile (mi2) 2.590 square kilometer

Mass

tons 907.1847 kilograms

tons per square mile (tons/mi2) 350.26 kilograms per square kilometer

Rate

cubic foot per second (ft3/s) 0.2832 cubic meter per second

million gallons per day (Mgal/d) 0.04381 cubic meters per second

tons per year (tons/yr) 907.1847 kilograms per year

Temperature

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

° F = 1.8 (° C) + 32
ix

ACRONYMS

ACF Apalachicola–Chattahoochee–Flint

ADEM Alabama Department of Environmental Management

ARC Atlanta Regional Commission

CSO combined sewer overflow(s)

FGFWFC Florida Game and Fresh Water Fish Commission

FLDER Florida Department of Environmental Regulation

GEPD Georgia Environmental Protection Division

GGS Georgia Geologic Survey

GWIS Ground Water Information System

GWUDS Georgia Water-Use Data System

LOWESS LOcally WEighted Scatterplot Smoothing

MCL maximum contaminant level(s)

NADP/NTN National Atmospheric Deposition Program/National Trends Network

NAWQA National Water-Quality Assessment

NPDES National Pollution Discharge Elimination System

NWIS National Water Information System

PCS Permit Compliance System

SSO sanitary sewer overflow(s)

STORET STOage and PETrieval System

STP Sewage Treatment Plant

USACOE U.S. Army Corps of Engineers

USEPA U.S. Environmental Protection Agency

USFS U.S. Forest Service

USGS U.S. Geological Survey

WPCP Water Pollution Control Plant

WSFPA Water, Sewer, and Fire Protection Association

WWTF wastewater-treatment facility (facilities)

ABBREVIATIONS

mg/L milligram per liter

mg/L/yr milligram per liter per year

μg/L microgram per liter

N nitrogen

NH3 ammonia

NH3 plus NH4

+ total ammonia

NH4

+ ammonium

NO3

- nitrate

NO2

- nitrite

P phosphorus

PO4 phosphate

1

NUTRIENT SOURCES AND ANALYSIS OF NUTRIENT WATER-QUALITY DATA, 

APALACHICOLA–CHATTAHOOCHEE–FLINT RIVER BASIN,

GEORGIA, ALABAMA, AND FLORIDA, 1972–90

By Elizabeth A. Frick, Gary R. Buell, and Evelyn H. Hopkins

ABSTRACT

In 1991, the U.S. Geological Survey began fullscale implementation of the National Water-Quality 

Assessment (NAWQA) program. One of the initial 

tasks of the NAWQA program is to compile and 

evaluate existing data from individual study units. 

Available nutrient data from 1972 through 1990 water 

years were used to estimate nutrient sources to the 

Apalachicola–Chattahoochee–Flint (ACF) River basin 

and describe the presence, distribution, and transport of 

nutrients in surface and ground waters. 

In 1990, about 2,500 tons of nitrogen and 1,100 

tons of phosphorus were discharged as point-source 

loads by 127 municipal wastewater-treatment 

facilities (WWTF). Nonpoint-source inputs, an 

unknown percentage of which entered the hydrologic 

system, included about 120,000 tons of nitrogen and 

28,000 tons of phosphorus from animal manure; 

82,000 tons of nitrogen and 20,000 tons of 

phosphorus applied as fertilizer; and 24,000 tons of 

nitrogen from atmospheric deposition. Estimates of 

nutrient input to the ACF River basin were not made 

for natural sources and for the following anthropogenic sources: industrial-wastewater effluent; storm 

drains; sanitary and combined sewer outflows; and 

runoff from agricultural, urban, and suburban areas. 

Nutrient outflow from the Apalachicola River into 

Apalachicola Bay, Fla., was about 13 percent of 

estimated nitrogen sources and about 3 percent of 

estimated total-phosphorus sources in the ACF River 

basin.

For 1972–90, nutrient concentrations in surface 

water were high enough to warrant concerns about 

accelerated eutrophication based on total-phosphorus 

concentrations and to warrant concerns intermittently 

about toxicity to fish based on dissolved-ammonia 

concentrations downstream of wastewater-treatment 

outfalls from Metropolitan Atlanta and LaGrange, Ga. 

Many improvements to the water quality of the 

Chattahoochee and Flint Rivers in the 1980’s and 

early 1990’s can be directly attributed to improvements in WWTF, legislation directed at decreasing 

point-source loads of phosphorus, and changes in 

locations of wastewater-treatment outfalls. However, 

limited data indicate that nonpoint-source inputs 

increased upstream of Atlanta and in the Chipola 

River watershed.

Significant increases in nutrient concentrations, 

loads, and yields occurred from upstream to downstream of the metropolitan areas of Atlanta, Ga.; 

Columbus, Ga., and Phenix City, Ala.; and Albany, 

Ga. The highest mean-annual yields estimated in the 

ACF River basin for total nitrogen (2.9 tons per 

square mile (tons/mi2

)), total-inorganic nitrogen (2.0 

tons/mi2), dissolved ammonia (1.1 tons/mi2), and 

total phosphorus (0.75 tons/mi2) were downstream of 

Atlanta.

Most significant trends in nutrient-concentration 

data from 1980–90 in the Chattahoochee River and the 

Middle and Lower Flint River basins were increasing, 

except dissolved ammonia which decreased at several 

sampling sites in reaches downstream of Atlanta, 

Columbus and Phenix City, and Albany. At sampling 

sites on the Chattahoochee and Flint Rivers 

downstream of Atlanta and Albany, decreasing trends 

in dissolved-ammonia concentration and increasing 

trends in dissolved-nitrate concentration were the 

result of improved wastewater treatment at WWTF. 

Dissolved-ammonia concentrations decreased and 

dissolved-nitrate concentrations increased along river 

reaches downstream of wastewater-treatment facility 

outfalls for Atlanta and Albany because of 

nitrification of ammonia to nitrate. Increasing trends in 

total-phosphorus concentrations are an accurate 

representation of data for the period 1980–90. 

However, legislated restrictions on the use of 

phosphate detergents and improvements to WWTF in 

the late 1980’s and early 1990’s, resulted in 

substantial reductions of phosphorus concentrations 

in wastewater effluent and in rivers at many locations 

in the 1990’s.
2

Reservoirs affect nutrient transport because of 

uptake by phytoplankton and aquatic plants, denitrification, and accumulation of phosphorus associated 

with sediment in reservoirs. Yields of total-inorganic 

nitrogen, dissolved ammonia, dissolved nitrate, and 

total phosphorus decreased between sampling sites 

upstream and downstream of four reservoirs on the 

Chattahoochee River. The only exception was the 

yield of dissolved ammonia increased slightly from 

upstream to downstream of Lake Sidney Lanier. 

Much of the nutrient load in the Chattahoochee River 

downstream of Atlanta is utilized by algae or settles 

out primarily in West Point Lake, and to a lesser 

extent, in Lake Harding and Walter F. George 

Reservoir. In general, the Flint River arm of Lake 

Seminole had significantly higher concentrations of 

nutrients than the Chattahoochee River arm of Lake 

Seminole, which may be the result of the large 

percentage of the Middle and Lower Chattahoochee 

River in backwater from reservoirs, the absence of 

reservoirs on the Flint River downstream of Albany 

until Lake Seminole, and nonpoint-source inputs of 

nutrients from intensively farmed areas in the Lower 

Flint River basin. Decreases in dissolved-ammonia, 

dissolved-nitrate, and total-phosphorus concentrations in reservoirs and backwater along the 

Chattahoochee River from West Point Lake to Lake 

Seminole during summer months are related to the 

seasonality of phytoplankton production.

The Chipola River had the highest yields of 

dissolved nitrate (1.2 tons/mi2) estimated in the ACF 

River basin. Estimated loads of dissolved nitrate 

increased fairly steadily from 500 to 1,500 tons per 

year from 1972–90. These factors strongly suggest an 

agricultural nonpoint source of elevated dissolvednitrate concentrations from increased irrigated 

agriculture and fertilizer applications in the Chipola 

River watershed. 

Analyses of nutrients in ground water within the 

ACF River basin for 1972–90 water years were 

restricted because of limited available data. The 

distribution of nitrate concentrations in the ACF River 

basin for 1972–90 water years included 10 percent of 

wells and 6 percent of springs with concentrations 

that probably have elevated nitrate concentrations (3.1 

to 10 milligrams per liter (mg/L)), and 1 percent of 

wells with median nitrate concentrations exceeding 

the maximum contaminant level of 10 mg/L. 

Dissolved-nitrate concentrations were significantly 

lower in the Providence aquifer than in the Floridan 

aquifer system and the crystalline-rock aquifers. 

Dissolved-nitrate concentrations in wells used for 

public supply were significantly lower than in wells 

used for domestic use or unused wells.

INTRODUCTION

In 1991, the U.S. Geological Survey (USGS) 

began full-scale implementation of the National 

Water-Quality Assessment (NAWQA) program. The 

three major objectives of the program are to provide a 

nationally consistent description of current waterquality conditions for a large part of the Nation’s 

water resources; define long-term trends (or lack 

thereof); and identify, describe, and explain the major 

factors that affect observed water-quality conditions 

and trends (Hirsch and others, 1988; Leahy and 

others, 1990). The NAWQA program, when fully 

implemented, will include investigations of hydrologic systems in 60 study units that include parts of 

most major river basins and aquifer systems in the 

United States. Study units range in size from 1,200 to 

about 65,000 square miles (mi2

), and incorporate 60 

to 70 percent of the Nation’s water use and population 

served by public water-supply systems. The 

Apalachicola–Chattahoochee–Flint (ACF) River 

basin was among the first 20 NAWQA study units 

selected for study under the full-scale implementation 

plan (Wangsness and Frick, 1991).

One of the initial tasks of the NAWQA program 

is to compile and evaluate existing data from 

individual study units. These data provide an 

historical perspective on the water quality in a study 

unit, strengths and weaknesses of available 

information, and implications for water-quality 

issues, study priorities, and study design. In addition 

to analyzing historical data on a regional scale, 

nutrients (Puckett, 1994; Puckett, 1995; Mueller and 

others, 1995) and pesticides (Barbash and Resek, 

1996; Larson, S.J., Capel, P.D., and Majewski, M.S., 

U.S. Geological Survey, written commun., 1996; 

Majewski and Capel, 1995; Nowell, L.H., Dileanis, 

P.D., and Capel, P.D., U.S. Geological Survey, written 

commun., 1996) are the first two topics being 

investigated on a national scale to evaluate 

differences among various regions of the country. 

Stell and others (1995) describes use and occurrence 

of pesticides in the ACF River basin. This report 

describes and evaluates available nutrient data in the 

ACF River basin.

Nutrients, particularly nitrogen and phosphorus, 

are important because their availability can regulate 

or limit the productivity of organisms in freshwateraquatic systems. High concentrations of nitrogen and 

phosphorus can adversely affect surface-water quality 

through eutrophication (abundant accumulation of 

nutrients causing excessive aquatic-plant growth) and 

toxicity to aquatic life. High concentrations of nitrate, 

found primarily in ground water, can be toxic to 

warm-blooded animals that drink the water.
3

Purpose and Scope

The purposes of this report are to (1) quantify 

nutrient sources to the ACF River basin and (2) 

present graphical and statistical analyses describing 

regional variations in the presence, distribution, and 

transport of nutrients in surface and ground waters of 

the ACF River basin. Where possible, variations in 

nutrient water quality are related to hydrologic, 

environmental, and anthropogenic factors. This evaluation is intended to provide a historical description of 

nutrient water-quality conditions in the ACF River 

basin, help guide the intensive sampling phase of the 

ACF NAWQA study with respect to nutrients, and 

provide regional interpretation of nutrient distribution 

in the ACF for the national synthesis on nutrients. It 

is outside the scope of this report to attempt to explain 

specific chemical processes affecting nutrients within 

the ACF River basin.

This evaluation is based on available and 

accessible nutrient data collected from the ACF River 

basin during 1972–90 water years1/. Nutrient sources 

to the ACF River basin were estimated for 1990. 

Analyzed nutrient water-quality data were from three 

computerized data bases—the USGS National Water 

Information System (NWIS), U.S. Environmental 

Protection Agency (USEPA) STOrage and RETrieval 

System (STORET), and Florida Department of 

Environmental Regulation (FLDER) Ground Water 

Information System (GWIS). Some discharge and 

concentration data from major wastewater-treatment 

facilities (WWTF) were computerized from paper 

files.

Description of the

Apalachicola–Chattahoochee–Flint River basin

The following three sections provide a brief 

description of the environmental setting of the ACF 

River basin. A more thorough description is in Couch 

and others (1996).

Location and Physiography

The ACF River basin NAWQA study area (fig. 1) 

is about 20,400 mi2

. This number includes the 

drainage area at the mouth of the Apalachicola River 

(19,600 mi2

) (U.S. Army Corps of Engineers, 1985); 

the New River watershed (about 510 mi2

) (U.S. 

Geological Survey digital files); and the Apalachicola 

Bay and surrounding coastal areas and barrier islands 

(about 270 mi2

) (U.S. Geological Survey digital files). 

The Chattahoochee and Flint Rivers merge in Lake 

Seminole to form the Apalachicola River, which 

flows through the panhandle of Florida into the 

Apalachicola Bay, and discharges into the Gulf of 

Mexico. The ACF River basin NAWQA study area is 

further subdivided according to 14 cataloging units 

shown on hydrologic unit maps (U.S. Geological 

Survey 1975a,b,c). The cataloging units, referred to as 

subbasins in this report (fig. 2), have differing 

physiography, climate, hydrologic characteristics, 

population densities, and land and water uses 

resulting in differences in surface-water and groundwater quality. Wherever possible, information in this 

report is presented at the subbasin, major river basin, 

and study-unit scales.

The ACF River basin lies in three physiographic 

provinces: the Blue Ridge Province, which includes 

the headwaters of the Chattahoochee River in the 

northwestern part of the study area; the Piedmont 

Province, which includes the Upper and Middle 

Chattahoochee River subbasins and the Upper Flint 

River subbasin; and the Coastal Plain Province, which 

includes approximately the southern half of the basin 

(fig. 1). The Fall Line, a physiographic boundary 

rather than a geologic boundary in most areas, 

approximates the boundary between older crystalline 

rocks of the Piedmont and younger sedimentary rocks 

and unconsolidated sediments of the Coastal Plain.

Climate and Hydrologic Setting

The ACF River basin is in a warm, temperate, 

subtropical climate zone that is moist year round and 

has hot summers. Average annual precipitation ranges 

from 45 to 60 inches (in.), primarily as rainfall 

(Hodler and Schretter, 1986). Average annual runoff 

ranges from approximately 12 to 40 in. (Stokes and 

McFarlane, 1993; U.S. Geological Survey, 1993; 

Pearman and others, 1993). Average annual 

temperatures range from 60 ° F in the northern part to 

70 ° F in the southern part of the basin. Evapotranspiration ranges from about 32 to 42 in., and generally increases from north to south (Hodler and 

Schretter, 1986).

Within the Piedmont (fig. 1), the course of the 

upper Chattahoochee River is strongly controlled by 

geologic structures (primarily faults) and has a 

rectangular drainage pattern; whereas, the Flint River 

has a dendritic drainage pattern. In the Coastal Plain, 

the rivers and their tributaries are incised into the 

underlying aquifers and receive substantial amounts 

of ground water from these aquifers. The Chattahoochee River drains 8,770 mi2

 and flows 430 mi and the 

Flint River drains 8,460 mi2 and flows 350 mi (U.S.

1/ Water year is the 12-month period, October 1 through 

September 30. The water year is designated by the 

calendar year in which it ends and which includes 9 of 

the 12 months. Thus, the year ending September 30, 

1990, is called the “1990 water year.”
30°

31°

33°

34°

84°

85°

32°

0 20 40 60 80 MILES

0 20 40 60 80 KILOMETERS

Alabama

Florida

Alabama

Florida

Georgia

Florida

Georgia

Florida

Alabama

Georgia

Blue Ridge

Coastal Plain oastal Plain

Piedmont Piedmont

★

Columbus

Dothan

Albany

Phenix City Phenix City

Bainbridge ainbridge

Dothan

LaGrange

Atlanta

Newton

Albany

Phenix City

Lake

Seminole Seminole

Walter F Walter F

George

Reservoir Reservoir

Lake

Harding Harding

Lake

Harding

Lake

Sidney

Lanier

Lake

Sidney

Lanier

West

Point

Lake

Chattahoochee RiverChattahoochee River

Flint River Lake

Walter F Blackshear

George

Reservoir

Lake

Seminole

Apalachicola Bay

Gulf of Mexico

Atlantic Ocean

Chipola River

Lake 

Worth

Apalachicola River

Alabama Georgia

ACF

Florida

Base from U.S. Geological Survey digital files 

Figure 1. Location of the Apalachicola-Chattahoochee-Flint River basin including physiographic provinces.

Fall Line

4
EXPLANATION

03130001 SUBBASIN—number indicates

 hydrologic unit code

CHATTAHOOCHEE RIVER BASIN

03130001 Upper Chattahoochee

03130002 Middle Chattahoochee—

 Lake Harding

03130003 Middle Chattahoochee—

 Walter F. George Reservoir

03130004 Lower Chattahoochee

FLINT RIVER BASIN

03130005 Upper Flint

03130006 Middle Flint

03130007 Kinchafoonee-Muckalee

03130008 Lower Flint

03130009 Ichawaynochaway

03130010 Spring

APALACHICOLA RIVER BASIN

03130011 Apalachicola

03130012 Chipola

03130013 New

03130014 Apalachicola Bay

03130001 0130001

0130002

0130003

03130002

0130005

0130007 0130006

03130005

03130007 03130006

03130008 3130008

03130009 0130009

03130010 0130010

03130011 3130011

03130013 3130013

03130014

03130012 0130012

03130003

03130004 0130004

Base from U.S. Geological Survey digital files

Figure 2. Location of subbasins and corresponding hydrologic unit codes, Apalachicola-ChattahoocheeFlint River basin (from U.S. Geological Survey, 1975a,b,c).

0 20 40 60 80 MILES

0 20 40 60 80 KILOMETERS

30°

31°

33°

34°

84°

85°

32°

5
6

Army Corps of Engineers, 1985). The confluence of 

the Chattahoochee and Flint Rivers is the headwaters 

of the Apalachicola River. The Apalachicola River 

flows unimpeded for 108 mi from its headwaters just 

below Jim Woodruff Lock and Dam to the Apalachicola Bay. With a mean annual discharge of 25,960 

cubic feet per second (ft3/s) from 1978–92, the 

Apalachicola River is the largest river in Florida and 

the 21st largest river in the conterminous United States 

(Leitman and others, 1983). Its width ranges from 

several hundred feet when confined to its banks to 

nearly 4-1/2 mi during flood stage in winter months 

(Leitman and others, 1983; Leitman and others, 

1991).

The Middle and Lower Flint subbasins are 

underlain by the highly transmissive Floridan aquifer 

system and these subbasins tend to have higher 

recharge rates and lower runoff than the rest of the 

ACF River basin. Baseflow measurements and 

ground-water modeling results (Torak and others, 

1993, p. 15 and 32) indicate that the Flint River acts 

as a major regional drain for the Upper Floridan 

aquifer from Lake Worth to Newton, Ga.

Sixteen reservoirs have altered the natural 

streamflow and riverine ecosystems within the study 

area. The Chattahoochee River has three major 

reservoirs—Lake Sidney Lanier, West Point Lake, 

and Walter F. George Reservoir—that account for 

approximately 99 percent of the surface-storage 

capacity in the ACF River basin. Nine of 10 other 

reservoirs on the Chattahoochee River are run-of-theriver reservoirs with little or no storage capacity (U.S. 

Army Corps of Engineers, 1984). The Flint River has 

two reservoirs—Lake Blackshear and Lake Worth. Jim 

Woodruff Dam forms Lake Seminole at the 

headwaters of the Apalachicola River. All reservoirs 

in the ACF River basin were built prior to 1972 

except West Point Lake, which began to be filled in 

October 1974 and reached maximum power pool in 

June 1975. Effects of reservoirs on annual flow 

distributions are overshadowed by natural variations 

in the ACF River basin (Leitman and others, 1991, p. 

230). However, the six reservoirs with storage 

capacity affect downstream flows over shorter time 

scales and moderate extreme low and high flows. 

Where historical data were sufficient, changes in 

nutrient chemistry as a result of lacustrine 

environments created by man-made impoundments 

on the mainstem rivers were evaluated by comparing 

nutrient data upstream and downstream of dams.

For this report, the ACF River basin is 

subdivided into six aquifers (fig. 3) within geologic 

units of different ages, lithology, and physical characteristics, all of which can influence chemical 

characteristics of ground water. The crystalline-rock 

aquifers are composed of Pre-Cambrian to Permian 

metamorphic and igneous rocks of the Blue Ridge and 

Piedmont. In general, these rocks supply small 

amounts of ground water, although increasing population is causing renewed interest in developing ground 

water as a source of public supply. From the Fall Line 

to the Gulf of Mexico, progressively younger Coastal 

Plain sediments crop out and overlie older sediments, 

stratigraphic thicknesses of units generally increase, 

and vertical and areal facies changes occur within 

units. The regional direction of ground flow in the 

Coastal Plain physiographic province within the ACF 

River basin is from north to south; however, there are 

local variations in ground-water flow direction, 

especially in the vicinity of major streams and in areas 

of large ground-water withdrawals. Aquifer boundaries are not always coincident with stratigraphic 

boundaries and naming conventions for stratigraphic 

units and aquifers are not uniform across state lines 

within the study area. Aquifer names in this report 

conform primarily to those used in the literature 

discussing geology and hydrogeology in Georgia. 

From youngest to oldest, aquifers within the Coastal 

Plain of the ACF River basin include the: surficial 

aquifer system, Floridan aquifer system, Claiborne 

aquifer, Clayton aquifer, and Providence aquifer (fig. 

4). The surficial aquifer system outcrop includes 

sediments deposited in a variety of fluvial and marine 

environments including river terraces, floodplain, 

delta, and coastal scarps. Coastal Plain aquifers within 

the ACF River basin are composed primarily of 

Upper Cretaceous to Quaternary inter-bedded sand, 

clay, limestone, and marl that are heavily used for 

domestic, industrial, and agricultural water supplies.

Population, Land Use, and Water Use

 In 1990, the population of the ACF River basin 

was about 2.64 million people (table 1). Population 

estimates for the study area were made using a 

geographic information system to total U.S. Bureau of 

the Census population estimates for census tracts by 

subbasin. Population densities were highest in the 

Upper and Middle Chattahoochee subbasins, which 

include much of the Metropolitan Atlanta area. Sixty 

percent of the population of the study area live in the 

Metropolitan Atlanta area. However, southeast 

Atlanta and the eastern and northwestern suburbs of 

the Atlanta area are outside the study area (in the 

Ocmulgee and Etowah subbasins). Other large population centers in the basin include Columbus, Ga.; 

Phenix City, Ala.; Albany, Ga.; and the eastern part of 

Dothan, Ala. (fig. 1). Most other cities and towns in 

the ACF River basin have populations of less than 

50,000 people. Population within the study area grew 

by approximately 16 percent from 1970–80, and by 

13 percent from 1980 – 90, although populations of
85° 84°

34°

33°

32°

31°

30° 0

0 20 40 60 80 KILOMETERS

20 40 60 80 MILES

Figure 3. Generalized outcrop areas for geologic and hydrogeologic units underlying the 

Apalachicola-Chattahoochee-Flint River basin (modified from Georgia Geologic Survey, 1976; 

Miller, 1986; and Geological Survey of Alabama, 1989).

Base modified from U.S. Geological Survey digital files

Surficial aquifer system

Floridan aquifer system

Claiborne aquifer and

 associated Eocene strata

Clayton aquifer and 

 associated Paleocene strata

Providence aquifer and associated

 Upper Cretaceous strata

Crystalline-rock aquifers

Gulf of Mexico

Fall Line

GENERALIZED OUTCROP AREAS

EXPLANATION

7
System

Quaternary

Tertiary

Cretaceous Upper

Cretaceous

HolocenePleistocene

Pliocene

Miocene

Oligocene

Eocene

Paleocene

Series Hydrogeologic

Units

Surficial aquifer

system

Floridan aquifer

system

Claiborne aquifer

Clayton aquifer

Providence aquifer

Chattahoochee and Flint

River Valley Geologic Units

Terrace and undifferentiated

deposits

Undifferentiated overburden

Hawthorn Formation Hawthorn Formation

Tampa Limestone

Suwanee Limestone Suwanee

Limestone

Ocala

Limestone

Moodys Branch

Formation Moodys Branch Formation

Lisbon

Formation

Tallahatta

Formation

Unnamed

units

Unnamed

units

Unnamed

units

Unnamed

units

Nanafalia and

Baker Hill

Formations

Hatchitigbee

and Bashi

Formations

Tuscahoma

Formation

Porters Creek

Clay

Unnamed

units Providence Sand

Unnamed

units Ripley Formation

Clayton Formation

Mariana Limestone

Ocala Limestone

Lisbon Formation

Tallahatta Formation

Undifferentiated

Paleocene and

Upper Cretaceous

strata

Terrace and undifferentiated

deposits

Florida Panhandle

Geologic Units

Citronelle Formation

North South

Figure 4. Generalized geologic and hydrogeologic units in the Coastal Plain of the Apalachicola–

Chattahoochee–Flint River basin. Gray area represents principle water-bearing strata; blank area 

represents missing strata (modified from Wagner and Allen,1984; Faye and Mayer, 1996; and 

Georgia Geologic Survey, written communication, 1996).

Confining unit

Confining unit

Confining unit

Confining unit

Alum Bluff

Group

Undifferentiated deposits

8

several subbasins in the southern and more rural part 

of the study area have decreased in the last 20 years 

(table 1).

Forest and agriculture were the dominant land 

cover and land use within the ACF River basin, 

accounting for 59 and 29 percent of the study area, 

respectively (table 2). Land-use and land-cover 

estimates listed in table 2 and shown in figure 5 are 

based on 1972–78 high-altitude aerial photography 

(U.S. Geological Survey, 1979a–f, 1980a–c), with 

urban areas updated to include all census tracts with 

population densities greater than 1,000 people per 

square mile in 1990 (U.S. Bureau of Census, 1991a,b, 

c; Hitt, 1994). This method of updating urban land use 

increased estimates of urban land use in the Upper and 

Middle Chattahoochee subbasins (predominantly in 

the Metropolitan Atlanta area) from 440 mi2 for 

1972–78 to 640 mi2

 for 1990. The increase in urban 

land use for the entire basin was from about 820 to 

1,100 mi2 (4.1 to 5.3 percent of the study area). On a 

regional scale, changes in land use from the mid1970’s to the early 1990’s were primarily the result of 

urban growth around Atlanta and conversion of rowcrop agricultural land to pine trees in the Coastal 

Plain. Most agricultural land in the Upper and Middle
Table 1. Population distribution, by subbasin, Apalachicola–Chattahoochee–Flint River basin, 1970, 1980, and 1990

[Numbers may not add to totals because of independent rounding]

Hydrologic

unit code

(figure 2)

Subbasin name

Population

Percent of 1

populatio

1/1970 2/1980 3/1990

03130001 Upper Chattahoochee 683,000 809,000 905,000 34 03130002 Middle Chattahoochee–Lake Harding 469,000 555,000 691,000 26 03130003 Middle Chattahoochee–Walter F. George Reservoir 263,000 267,000 276,000 10 03130004 Lower Chattahoochee 37,300 44,800 51,400 1.9 

 Subtotal—Chattahoochee River basin 1,450,000 1,680,000 1,920,000 73 

03130005 Upper Flint 210,000 273,000 354,000 13 03130006 Middle Flint 57,400 63,900 66,600 2.5 03130007 Kinchafoonee-Muckalee 39,000 44,000 52,300 2.0 03130008 Lower Flint 110,000 124,000 117,000 4.4 03130009 Ichawaynochaway 25,900 26,500 22,500 0.8 03130010 Spring 23,900 26,600 22,300 0.8 

Subtotal—Flint River basin 466,000 558,000 634,000 24 

03130011 Apalachicola 18,300 20,700 25,800 1.0 03130012 Chipola 49,600 60,000 52,800 2.0 03130013 New 4/4,500 4/4,960 3,760 0.1 03130014 Apalachicola Bay 4/ 4/ 2,770 0.1 

 Subtotal—Apalachicola River basin 72,400 85,700 85,200 3.2 

0313 TOTAL—Apalachicola–Chattahoochee–Flint River basin 1,990,000 2,320,000 2,640,000 100 

9

1/Modified from U.S. Bureau of the Census 1970 population estimates by county, U.S. Bureau of the Census, 1981d; and U.S. Geological Survey, 1975a,b,c.3/Modified from U.S. Bureau of the Census, 1981d; and U.S. Geological Survey, 1975a,b,c.3/Modified from U.S. Bureau of the Census, 1991a,b,c; and U.S. Geological Survey, 1975a,b,c.4/Population estimates for 1970 and 1980 in the New and Apalachicola Bay subbasins are both included in New (03130013) subbasin.
Table 2. Land-use and land-cover distributions, by subbasin, Apalachicola–Chattahoochee–Flint River basin

[mi2, square miles; <, less than; numbers may not add to totals because of independent rounding; updates of land-use data in urban areas based on U.S

population estimates; rangeland accounts for less than nine square miles (less than 0.1 percent) in the Apalachicola–Chattahoochee–Flint River basin; 

Survey (1979a–f, 1980a–c) and U.S. Bureau of the Census (1991)]

Hydrologic 

unit code

(figure 2)

Subbasin name

Anderson Level I—Land-Use and Land-Cover Classifications 

Urban or 

built-up land Agricultural land Forest land Water Wetland Ba

(mi2) (percent) (mi2) (percent) (mi2) (percent) (mi2) (percent) (mi2) (percent) (mi2

03130001 Upper Chattahoochee 350 22 220 14 930 59 56 3.6 <1 <0.1 17 03130002 Middle Chattahoochee–Lake Harding 280 9.2 460 15 2,200 72 76 2.5 2 0.1 26 03130003 Middle Chattahoochee–Walter F. George 

Reservoir

130 4.6 420 15 2,200 77 70 2.5 20 0.7 15 

03130004 Lower Chattahoochee 18 1.4 570 46 610 49 32 2.5 20 1.6 3 

Subtotal—Chattahoochee River basin 780 9.0 1,700 19 5,900 68 230 2.7 42 0.5 61 

03130005 Upper Flint 140 5.2 670 25 1,700 65 10 0.4 98 3.7 14 03130006 Middle Flint 28 1.8 790 50 660 42 15 1.0 67 4.3 2 03130007 Kinchafoonee-Muckalee 20 1.8 480 44 540 49 2 0.2 53 4.8 2 03130008 Lower Flint 53 4.1 640 50 530 41 18 1.4 43 3.3 5 03130009 Ichawaynochaway 8 0.8 550 49 400 36 3 0.3 150 14 1 03130010 Spring 9 1.2 470 61 240 32 16 2.1 26 3.3 5 

Subtotal—Flint River basin 250 3.0 3,600 43 4,100 48 65 0.8 440 5.2 28 

03130011 Apalachicola 13 1.2 120 10 650 58 26 2.3 310 28 4 03130012 Chipola 23 1.8 450 35 650 50 9 0.7 160 12 7 03130013 New 4 0.9 <1 <0.1 380 74 9 1.7 120 22 1 03130014 Apalachicola Bay 5 1.8 <1 <0.1 44 16 200 75 15 5.4 3 

Subtotal—Apalachicola River basin 45 1.4 570 18 1,700 54 240 7.6 600 19 15 

0313 TOTAL—Apalachicola–Chattahoochee– Flint River basin 1,100 5.3 5,800 29 11,700 58 540 2.7 1,100 5.3 100 

10

1/Unrounded drainage areas (U.S. Army Corps of Engineers, 1985).
EXPLANATION

URBAN LAND

AGRICULTURAL LAND

FOREST LAND

WETLAND

WATER 

Base from U.S. Geological Survey digital files

Figure 5. Land use, Apalachicola-Chattahoochee-Flint River basin. Barren land (120 square miles) and 

range land (9 square miles) are not visible at this scale (modified from U.S. Geological Survey land use 

and land cover digital data, 1972–78; urban areas expanded based on U.S. Bureau of the Census 1990 

population estimates).

0 20 40 60 80 MILES

0 20 40 60 80 KILOMETERS

30°

31°

33°

34°

84°

85°

32°

11
12

Chattahoochee and Upper Flint River subbasins is 

used for pastures, and to a lesser extent, poultry production, while most agricultural land in the southern 

ACF River basin is used for row crops and, to a lesser 

extent, orchards. Wetland areas accounted for about 

5.4 percent of the entire basin, and as much as 14 

percent of the Ichawaynochaway subbasin and 28 

percent of Apalachicola subbasin. Range land, barren 

land, and water accounted for the remaining area.

Approximately 2,100 million gallons per day 

(Mgal/d) of freshwater were withdrawn from the ACF 

River basin in 1990, of which about 17 percent was 

consumptively used (Marella and others, 1993). 

Surface-water withdrawals were approximately 1,790 

Mgal/d (85 percent of all withdrawals). Of the 

surface-water withdrawals, about 860 (48 percent) 

were for thermoelectric power generation and about 

388 Mgal/d (22 percent) were for public supply in the 

Chattahoochee River basin (table 3). Ground-water 

withdrawals accounted for 303 Mgal/d (14 percent of 

all withdrawals), about 129 Mgal/d (43 percent) of 

which were for agriculture in the Flint River basin. 

The Floridan aquifer system supplied 44 percent of 

the ground water withdrawn in 1990, followed by the 

Claiborne, Clayton, and crystalline-rock aquifers 

(Marella and others, 1993, p. 11). Thermoelectric 

power generation accounted for 51 percent of all 

water withdrawals in the ACF River basin in 1990; 

however, less than one percent was consumed (Fanning and others, 1991, p. 24–25). Public supply 

accounted for 23 percent of all water withdrawals 

which was followed by agriculture (12 percent), selfsupplied commercial and industrial (12 percent), and 

self-supplied domestic (2 percent); (table 3). Total 

water withdrawals increased by 42 percent between 

1970–90; primarily because ground-water withdrawals for irrigation increased by more than 2,000 

percent and surface-water withdrawals for public supply increased by more than 300 percent. Marella and 

others (1993) provide a more detailed description of 

water use in the ACF River basin in 1990 and trends 

in water use from 1970–90.

Acknowledgments

The authors wish to thank various Federal and 

State agencies and private organizations for their 

cooperation in providing information and data that 

were used in preparing this report. Special thanks are 

extended to municipal wastewater-treatment facility 

managers and laboratory supervisors who provided 

data. Joseph C. DeVivo, USGS, helped with 

compilation of municipal-wastewater effluent data 

and point-source load estimates. David J. Wangsness, 

James B. McConnell, and Charles R. Kratzer, USGS, 

provided many excellent technical suggestions.

NUTRIENT SOURCES

Major sources of nutrients to the ACF River 

basin estimated in this report include municipalwastewater effluent, animal manure, fertilizer, and 

atmospheric deposition. Estimates of point-source 

loads and nonpoint-source inputs of nutrients for 1990 

(table 4) are based on data of varying accuracy and 

completeness from Federal, State, and local 

agencies. Estimates of nutrient input to the ACF 

River basin from the following sources were not 

made: ground water flowing into the basin; leeching 

of nutrients from soils to ground water; organic 

compounds used in the basin which contain nitrogen 

and phosphorus; runoff from agricultural, urban, and 

suburban areas; septic systems; decomposition of 

organic matter; industrial-wastewater effluent; storm 

drains; and sanitary and combined sewer overflows.

Point-Source Loads

Point sources discharge directly to surface or 

ground water or are applied to land surface in a 

confined area or point. Point sources of nutrients in 

the ACF River basin include municipal- and 

industrial-storm drains, wastewater effluent, sanitary 

and combined sewer overflows, and untreated wastes 

or runoff from illegal outfall pipes. However, the only 

nutrient point-source loads estimated in this report 

were for municipal-wastewater effluent. Effluent from 

municipal facilities contained about one percent of 

estimated nitrogen sources and about two percent of 

estimated phosphorus sources to the ACF River basin 

in 1990 (table 4). While these are small percentages 

of the estimated nutrient sources to the basin, they are 

very important because unlike nonpoint-source 

inputs, all point-source loads of nutrients directly 

enter the hydrologic system.

Point-source nutrient loads from storm drains, 

sanitary sewer overflows (SSO), and combined sewer 

overflows (CSO) are not included in estimates in table 

4. Storm drains transport storm runoff from streets, 

parking lots, and other impervious surfaces. Sanitary 

sewers primarily transport raw sewage to WWTF and 

have overflow mechanisms where excess sewage 

spills to streams rather than backs up into buildings 

and homes. During dry periods, combined sewers 

primarily transport raw sewage to WWTF. During and 

after rain events, combined sewers transport a 

combination of raw sewage and storm runoff. Storm 

runoff often exceeds the capacity of combined sewers 

causing a mixture of untreated sewage and storm 

runoff to overflow directly into streams at CSO. Data 

were not available to estimate nutrient loads from 

storm drains and SSO.
Table 3. Water withdrawals by principal water-use categories, by subbasin, Apalachicola–Chattahoochee–Flint River basin, 1990

[Withdrawals are in million gallons per day; <, less than; numbers may not add to totals because of independent rounding; modified from Marella and o

Hydrologic 

unit code

(figure 2)

Subbasin name

Public supply Self-supplied domestic Self-supplied commercial and industrial Agricultural Thermoelectric power generation Total fre

Ground 

water

Surface 

water

Ground 

water

Surface 

water

Ground 

water

Surface 

water

Ground 

water

Surface 

water

Ground 

water

Surface 

water

Ground 

water

S

w

03130001 Upper Chattahoochee 2.42 243 6.88 0 1.03 3.96 0.90 5.26 0 0 11.2 203130002 Middle Chattahoochee–Lake Harding 1.66 96.7 6.72 0 1.20 26.9 1.48 4.08 0 761 11.1 803130003 Middle Chattahoochee–Walter F. 

 George Reservoir

1.70 48.3 0.94 0 0.13 37.0 1.75 6.01 0 0 4.52 

03130004 Lower Chattahoochee 6.40 0 1.27 0 0.49 107 18.1 7.01 0 98.8 26.3 2

 Subtotal—Chattahoochee River basin 12.2 388 15.8 0 2.85 175 22.3 22.4 0 860 53.1 1,4

03130005 Upper Flint 4.35 33.5 6.20 0 0.43 2.93 6.48 7.88 0 0 17.5 03130006 Middle Flint 3.88 0 1.70 0 9.50 9.43 14.9 10.4 0 15.0 30.0 03130007 Kinchafoonee-Muckalee 5.39 0 1.42 0 1.01 0 13.0 7.48 0 0 20.8 03130008 Lower Flint 22.5 0 1.30 0 11.0 0 46.5 8.50 0 92.8 81.3 103130009 Ichawaynochaway 2.69 0 0.65 0 0.31 0 18.4 8.80 0 0 22.0 03130010 Spring 2.21 0 0.82 0 0.20 0 29.6 3.99 0 0 32.8 

 Subtotal—Flint River basin 41.0 33.5 12.1 0 22.5 12.4 129 47.0 0 108 204 2

03130011 Apalachicola 1.64 0 2.16 0 2.55 0 11.1 4.78 0.37 108 17.8 103130012 Chipola 8.09 0 2.76 0 0.06 32.9 15.1 3.57 0 0 26.0 03130013 New 0.68 0 0.07 0 0 0 0 0 0 0 0.75 03130014 Apalachicola Bay 0.95 0 0.07 0 0 0 0 0 0 0 1.02 

 Subtotal—Apalachicola River basin 11.4 0 5.06 0 2.61 33.9 26.1 8.35 0.37 108 45.5 1

0313 TOTAL—Apalachicola-Chattahoochee- Flint River basin 64.5 421 33.0 0 27.9 221 177 77.8 0.37 1,080 303 1,7

TOTAL–by principal water-use category 486 33.0 248 255 1,080 2,100PERCENT–by principal water-use category 23 1.6 12 12 51 100

13
14

Table 4. Point-source loads and nonpoint-source inputs of nutrients, by subbasin, Apalachicola–Chattahoochee–Flint River basin, 1990[–, no available data; numbers may not add to totals because of independent rounding]

Hydrologic 

unit code

(figure 2)

Subbasin name

Nitrogen, in tons Phosphorus, in tons

Point-source 

loads Non-point source inputs Point-source loads Non-point source i

Municipal 

wastewater 

effluent

Animal manure

Fertilizer Atmospheric deposition Municipal wastewater effluent Animal manure Fertilizer 

(Ammonia as 

nitrogen)

(Total 

nitrogen)

(Total 

nitrogen)

(Nitrate plus 

ammonium as 

nitrogen)

(Total 

phosphorus)

(Total 

phosphorus)

(Total 

phosphorus)

03130001 Upper Chattahoochee 310 86,000 1,900 1,900 48 19,000 490 03130002 Middle Chattahoochee–Lake Harding 1,500 10,000 4,200 3,600 770 2,500 790 03130003 Middle Chattahoochee–Walter F. George 

Reservoir

390 3,300 5,200 3,400 140 870 890 

03130004 Lower Chattahoochee 78 1,700 8,900 1,500 14 520 2,400 

 Subtotal—Chattahoochee River basin 2,200 100,000 20,000 10,000 970 23,000 4,500 

03130005 Upper Flint 58 7,600 5,500 3,100 32 1,800 910 03130006 Middle Flint 18 4,500 12,000 1,800 18 1,100 3,000 03130007 Kinchafoonee-Muckalee 21 2,300 6,800 1,300 10 590 1,700 03130008 Lower Flint 62 1,800 12,000 1,500 54 510 3,000 03130009 Ichawaynochaway 9 750 7,600 1,300 4 220 1,900 03130010 Spring 14 850 10,000 910 6 260 2,900 

Subtotal—Flint River basin 180 18,000 55,000 10,000 120 4,500 13,000 

03130011 Apalachicola 11 210 1,500 1,300 5 64 680 03130012 Chipola 28 1,700 6,100 1,500 6 480 1,700 03130013 New 2 7 74 650 1 2 19 03130014 Apalachicola Bay 5 0 5 39 2 0 1 

 Subtotal—Apalachicola River basin 46 1,900 7,700 3,500 14 550 2,400 

TOTAL—Apalachicola–

Chattahoochee–Flint River basin

2,500 120,000 82,000 24,000 1,100 28,000 20,000 

0313
15

CSO discharge into the following tributaries of 

the Chattahoochee River in Metropolitan Atlanta—

Peachtree (three), Proctor (two), and Utoy Creeks 

(two) (Atlanta Regional Commission, 1989). 

Available nutrient concentration and discharge data 

for these CSO (Atlanta Regional Commission, 1989; 

Georgia Department of Natural Resource and U.S. 

Environmental Protection Agency, 1987; Black, 

Crow, & Eidness, Inc., and Jordan, Jones, & 

Goulding, Inc., 1975) are too limited to accurately 

estimate annual nutrient loads from CSO.

In 1990, the Georgia Legislature amended the 

Water Quality Control Act to require cities to 

eliminate CSO or treat the overflow to meet State 

water-quality standards. From 1985–97, the city of 

Atlanta has implemented or has plans to implement 

the following three abatement methods to treat 

overflow from or eliminate CSO:

• screen combined sewage to remove trash 

and solids and add chlorine to overflow to 

kill bacteria before discharging 

wastewater;

• off-line storage of combined sewage for 

later treatment at WWTF; and

• separate combined sewers into sanitary 

sewers and storm drains (Peter R. Maye, 

Georgia Department of Natural 

Resources, written commun., 1996).

The city of Columbus has two main CSO with 

vortex separators treating overflow (Peter R. Maye, 

Georgia Department of Natural Resources, oral 

commun., 1996).

Municipal-wastewater effluent

Average monthly discharge and nutrient 

concentrations for treated municipal-wastewater effluent were obtained from monthly Discharge Monitoring Reports filed with Georgia Environmental 

Protection Division (GEPD), Alabama Department of 

Environmental Management (ADEM), and FLDER. 

USEPA Permit Compliance System (PCS) was used 

to a lesser extent. Monthly average discharge data 

from the above sources were augmented by the USGS 

Georgia Water-Use Data System (GWUDS); and 

discharge and nutrient-concentration data were augmented from interviews and paper files at 7 of the 8 

WWTF that discharged more than 10 Mgal/d in 1990.

Nearly complete monthly average discharge 

records exist since 1976 for all municipal WWTF 

operating in the ACF River basin that discharge more 

than 1 Mgal/d (1.547 ft3/s), as a result of monitoring 

and reporting required by the National Pollution 

Discharge Elimination System (NPDES). Ammoniaand phosphorus-concentration data were much less 

complete, partially because of varied NPDES 

monitoring and reporting frequency requirements 

among facilities. In 1976, only one municipal 

wastewater-treatment facility in the ACF River basin 

reported monthly average ammonia and phosphorus 

concentrations. However, by 1980, most major 

municipal facilities with a design capacity larger than 

1 Mgal/d reported monthly average ammonia 

concentrations; and by 1986, all major facilities 

between Buford Dam (Lake Sidney Lanier) and West 

Point Lake reported monthly average phosphorus 

concentrations. Testing for nitrate, nitrite, total 

Kjeldahl nitrogen, total-organic nitrogen, and 

dissolved orthophosphate is infrequently required, 

and rarely performed by WWTF.

In 1990, an estimated 356 Mgal/d of treated 

municipal effluent (table 5) was discharged to streams 

or applied to land surfaces in the ACF River basin by 

approximately 127 municipal facilities (modified 

from Marella and others, 1993). Thirty-one major 

municipal facilities (table 6, fig. 6) accounted for 

about 330 Mgal/d (92 percent) and the six largest 

WWTF located in the Middle Chattahoochee 

subbasin accounted for 218 Mgal/d (61 percent) of all 

treated municipal effluent discharged into the ACF 

River basin in 1990. Effluent discharged from ten 

municipal WWTF that discharge more than 1 Mgal/d 

into the Chattahoochee River and its tributaries within 

Metropolitan Atlanta increased from 1980 to 1995 

(fig. 7). Although not completely comparable because 

of differences in county boundaries and service-area 

boundaries for municipal wastewater, increases in 

discharge approximately paralleled increases in 

population for the five Metropolitan Atlanta counties 

where these WWTF discharge.
Table 5. Municipal wastewater discharges, by subbasin, Apalachicola–Chattahoochee–Flint River basin, 1990

[Mgal/d, million gallons per day; numbers may not add to totals because of independent rounding; modified from Marella and others, 1993

Hydrologic unit 

code

(figure 2)

Subbasin name

Municipal wastewater discharge information, 1990

Land application of effluent Effluent dischar

Permitted 

amount1/

(Mgal/d)

Discharge2/ Permitted 

amount1/ 

(Mgal/d)

Mgal/d Percent M

03130001 Upper Chattahoochee 1.75 1.75 10.8 40.3 2903130002 Middle Chattahoochee–Lake Harding 9.49 9.49 58.7 277 237 03130003 Middle Chattahoochee–Walter F. George Reservoir 0.02 0.02 0.1 45.3 3003130004 Lower Chattahoochee 0 0 0 4.13 4

 Subtotal–Chattahoochee River basin 11.3 11.3 69.6 366 301 

03130005 Upper Flint 3/3.93 3/3.55 3/22.0 11.6 603130006 Middle Flint 0.75 0.75 4.6 8.83 303130007 Kinchafoonee-Muckalee 0 0 0 4.82 303130008 Lower Flint 0 0 0 27.2 1703130009 Ichawaynochaway 0 0 0 1.81 103130010 Spring 0 0 0 2.52 2

Subtotal–Flint River basin 3/4.68 3/4.30 3/26.6 56.7 34

03130011 Apalachicola 0.50 0.31 1.9 2.40 103130012 Chipola 0 0 0 4.37 203130013 New 0.55 0.30 1.9 0 0 03130014 Apalachicola Bay 0 0 0 1.00 0

Subtotal–Apalachicola River basin 1.05 0.61 3.8 7.77 4

0313 TOTAL–Apalachicola–Chattahoochee–Flint River basin

3/17.0 3/16.2 3/100 431 340 

16

1/ Permitted discharges are set by individual States as part of the National Pollution Discharge Elimination System (NPDES) administered by the U.S

Agency. 2/ For land-application systems where discharge data were not available, 1990 permitted amount was used as an estimate of 1990 discharge. 3/ Includes the Shoal Creek water-pollution control plant in Spalding County, which uses land application for six months, May to October, and discharemaining six months of each year.
17

Table 6. Nutrient loads from municipal wastewater facilities discharging more than one million gallons per day, by subbasin, Apalachicola

basin, 1990

[Mgal/d, million gallons per day; mg/L, milligrams per liter; NPDES, National Pollution Discharge Elimination System; STP, Sewage Treatment Plant; WPCP, Water PolluSewer, and Fire Protection Authority; WWTP, Waste Water Treatment Plant; –, no available data;Data sources: Alabama Department of Environmental Management; Florida Department of Environmental Regulation; Georgia Environmental Protection Division; U.S En

Permit Compliance System data base; U.S. Geological Survey, Georgia Water Use Data System; Individual plant Monthly Operating Reports]

Location 

number 

(figure 

6)

City or county State

 NPDES 

permit 

number

Facility name

River mile 

upstream of 

the mouth of 

the 

Apalachicola 

River

Facility discharge informa

Name of receiving water

body or disposal

system method

Permitted 

amount1/

(Mgal/d)

Dis

(M

Upper Chattahoochee (03130001)

1 Cornelia, City of Georgia GA0021504 Cornelia WPCP 3/499.37 South Fork Mud Creek 3.0 2 Gainesville, City of Georgia GA0020168 Gainesville WPCP No 2 (Linwood Drive) 5/477.8 Lake Sidney Lanier 3.0 3 Gainesville, City of Georgia GA0021156 Gainesville WPCP No 1 (Flat Creek) 7/466.77 Flat Creek 7.0 4 Gwinnett County Georgia GA0026433 Crooked Creek WPCP 8/432.92 Chattahoochee River 6.5 5 Fulton County Georgia GA0030686 Johns Creek WPCP 8/431.77 Chattahoochee River 5.0 6 Fulton County Georgia GA0024333 Big Creek WPCP 8/422.88 Chattahoochee River 11.0 

Middle Chattahoochee–Lake Harding (03130002)

7 Cobb County Georgia GA0026140 R.L. Sutton WPCP 8/408.22 Chattahoochee River 28.5 28 Atlanta, City of Georgia GA0021482 R.M. Clayton WPCP 9/408.17 Chattahoochee River 101 89 Cobb County Georgia GA0026158 South Cobb WPCP 8/402.11 Chattahoochee River 28.0 2

10 Atlanta, City of Georgia GA0021458 Utoy Creek WPCP 8/399.31 Chattahoochee River 37.0 211 Atlanta, City of Georgia GA0024040 South River WPCP 10/399.11 Chattahoochee River 41.0 312 Fulton County Georgia GA0025381 Camp Creek WPCP 8/391.30 Chattahoochee River11/ 13.0 113 Douglasville, City of Georgia GA0030341 Douglasville South WPCP 7/389.32 Annewakee Creek 1.7 14 Carroll County Georgia GAU020071 Carroll County Water Authority — Land disposal 9.45 15 Lanett, City of Alabama AL0023159 Lanett WWTP 12/304.8 Chattahoochee River 5.0 16 La Grange, City of Georgia GA0047244 Long Cane Creek WPCP 7/302.65 Long Cane Creek13/ 8.2 17 Chambers County Alabama AL0024724 East Alabama WSFPA l2/298.4 Chattahoochee River 4.0 

Middle Chattahoochee–Walter F. George Reservoir (03130003)

18 Phenix City Alabama AL0022209 Phenix City WWTP l2/264.6 Chattahoochee River 7.60 19 Columbus, City of Georgia GA0020516 Columbus South WPCP 5/262.9 Chattahoochee River 35.0 220 Eufaula, City of Alabama AL0020583 Eufaula WWTP 12/200.4 Chattahoochee River 2.0 
18

Lower Chattahoochee (03130004)

21 Dothan, City of Alabama AL0022764 Dothan Omusee Creek WWTP 7/155.57 Omusee Creek 4.0 4

Upper Flint (03130005)

22 Spalding County Georgia GA0047040 Shoal Creek WPCP14/ 15/413.67 Shoal Creek (January–April, 

November, December)

Land disposal (May–October)

1.5

16/116/0

23 Peachtree City Georgia GA0035777 Line Creek WPCP 7/404.15 Line Creek 2.0 124 Griffin, City of Georgia GA0030791 Potato Creek WPCP 7/358.07 Potato Creek 2.0 125 Thomaston, City of Georgia GA0020079 Bell Creek WPCP 17/358.07 Bell Creek 1.0 1

Middle Flint (03130006)

26 Cordele, City of Georgia GA0024503 Cordele WPCP 7/250.97 Gum Creek 5.0 2

Kinchafoonee-Muckalee (03130007)

27 Americus, City of Georgia GA0047767 Mill Creek WPCP19/ 20/212.10 20/211.62 Muckalee Creek near the confluence with Mill 

Creek

4.4 3

Lower Flint (03130008)

28 Albany, City of Georgia GA0020991 Albany WPCP 21/206.9 Flint River 20.0 1429 Camilla, City of Georgia GA0020362 Camilla WPCP 7/139.57 Big Slough 3.0 23/030 Bainbridge, City of Georgia GA0024678 Bainbridge WPCP 5/135.75 Flint River 2.5 1

Chipola (03130012)

31 Marianna, City of Florida FL0020117 Marianna STP 25/43.60 25/28.20 Chipola River 2.7 1

TOTAL–Effluent discharged by 31-municipal wastewater facilities23/ that discharged more than 1 Mgal/d in 1990 405 328PERCENT OF—Municipal wastewater effluent discharged into the Apalachicola–Chattahoochee–Flint River basin by 31-municipal 

 wastewater facilities23/ discharging more than 1 Mgal/d, 1990

90

(in percent)

92

(in pe

Table 6. Nutrient loads from municipal wastewater facilities discharging more than one million gallons per day, by subbasin, Apalachicola basin, 1990—Continued[Mgal/d, million gallons per day; mg/L, milligrams per liter; NPDES, National Pollution Discharge Elimination System; STP, Sewage Treatment Plant; WPCP, Water PollutSewer, and Fire Protection Authority; WWTP, Waste Water Treatment Plant; –, no available data;Data sources: Alabama Department of Environmental Management; Florida Department of Environmental Regulation; Georgia Environmental Protection Division; U.S Env

Permit Compliance System data base; U.S. Geological Survey, Georgia Water Use Data System; Individual plant Monthly Operating Reports]

Location 

number 

(figure 

6)

City or county State

 NPDES 

permit 

number

Facility name

River mile 

upstream of 

the mouth of 

the 

Apalachicola 

River

Facility discharge informa

Name of receiving water

body or disposal

system method

Permitted 

amount1/

(Mgal/d)

Disc

(Mg
19

 1/ Permitted discharge (average) for individual wastewater-treatment plants. Permits are set by state regulatory agencies as part of the U.S. Environmenta

program. 2/ Nutrient loads are estimated using the following formula:

Sum January to December (average monthly discharge (Mgal/d) x average monthly concentration (mg/L) x number of days in month x conversion fac1990;Load estimates are footnoted when average monthly discharge and(or) average monthly concentration are missing for one or more months in 1990. 3/ South Fork Mud Creek flows into Mud Creek which flows into the Chattahoochee River. River mile listed is for the confluence of Mud Creek and the C

Corps of Engineers, 1985). 4/ For Cornelia WPCP, 10 months of missing ammonia concentration data for 1990 were estimated using the average ammonia concentration for January 

 5/ River mile estimated from Victoria Trent, Georgia Geologic Survey, written commun., 1996; U.S. Army Corps of Engineers, 1985; and 1:24,000 scale  6/ For Gainesville WPCP No 2, nine months of missing ammonia concentration data for 1990 were estimated using the average ammonia concentration f

December 1990.

 7/ River mile listed is for the confluence of the tributary receiving effluent and the main stem river (Chattahoochee, Flint, or Apalachicola Rivers) (U.S. A 8/ Georgia Department of Natural Resources, 1994. 9/ U.S. Army Corps of Engineers, 1985; Georgia Department of Natural Resources, 1994. 10/ The Three Rivers Return outfall pipes effluent from the South River WPCP (east of the Apalachicola–Chattahoochee–Flint River basin) to the Chatta

from Georgia Department of Natural Resources, 1994. 11/ Effluent discharged to Chattahoochee River; from 1988–90 also used land disposal of sludge (Chris Crittenden, Camp Creek WPCP Supervisor, oral c

12/ River mile estimated from Will S. Mooty, U.S. Geological Survey, written commun, 1996; U.S. Army Corps of Engineers, 1985; and 1:24,000 scale to13/ Long Cane Creek WPCP moved its effluent discharge location to the Chattahoochee River approximately one mile below the confluence between the 

Cane Creek in September 1993 (Anne Westmoreland, Long Cane Creek WPCP, oral commun., 1994). 14/ Two Shoal Creeks flow from the east toward the Flint River. Shoal Creek Plant in Clayton County (NPDES Permit Number GAU020236) discharged le

land application of their effluent near a reservoir near the confluence of Shoal Creek and the Flint River. Shoal Creek WPCP in Spalding County (NP

GA0047040) alternates between land application of effluent in the summer and discharge of effluent into Shoal Creek (which flows into Wildcat Cree

in the winter.

15/ Shoal Creek flows into Wildcat Creek, which flows into the Flint River. River mile listed is for the confluence of Wildcat Creek and the Flint River (U

1985). 16/ In 1990, Shoal Creek WPCP in Spalding County discharged an average of 1.26 Mgal/d of effluent to Shoal Creek for the six months January to April, 

Average effluent discharged to the land-application system for the six months from May to October was 0.98 Mgal/d. 17/ Bell Creek flows into Potato Creek which flows into the Flint River. River mile listed is for the confluence of Potato Creek and the Flint River (U.S. A

18/ For Cordele WPCP, January, February, March, and April missing total-phosphorus concentration data were estimated using average total-phosphorus c

eight remaining months of 1990. The July total-phosphorus concentration was 6.9 mg/L (two to three times greater than in the other seven months rep

estimate the four months with missing concentrations because it appears there was a problem with phosphorus removal in July. 19/ In 1990, the city of Americus Mill Creek WPCP (NPDES Permit Number GA0047767) replaced the city of Americus Muckalee Creek WPCP (NPDE

and Willetts Branch WPCP (NPDES Permit Number GA0025090), which both were out of service by February 1990. 20/ Muckalee Creek flows into Muckafoonee Creek, which flows into Lake Worth on the Flint River. The first river mile listed is for the confluence of the 

Creek and Lake Worth and the second river mile listed is for the confluence of Muckafoonee Creek and the Flint River (U.S. Army Corps of Engineer

21/ River mile estimated from Julia L. Fanning, U.S. Geological Survey, written commun, 1996; U.S. Army Corps of Engineers, 1985; and 1:24,000 scale 22/ For Albany WPCP, seven months of missing ammonia concentration data for 1990 were estimated using the average ammonia concentrations for Janu

December 1990.

23/ Although effluent discharged by the Camilla WPCP was less than 1 Mgal/d in 1990, the plant is included in this table because discharges in 1989 and 

(1.32 and 1.25 Mgal/d, respectively) and ammonia concentration data are available. 24/ For Bainbridge WPCP, 12 months of missing ammonia concentration data for 1990 were estimated using the average ammonia concentration for Janu

25/ The first river mile listed is for the confluence of the Chipola Cut off and the Apalachicola River and the second river mile listed is for the confluence 

Apalachicola River (U.S. Army Corps of Engineers, 1985). 26/ For Marianna STP, September 1990, ammonia concentration was estimated using the average ammonia concentration for August and October 1990.
Base from U.S. Geological Survey digital files

Figure 6. Location of municipal-wastewater outfalls having discharges greater than one million gallons 

per day, Apalachicola-Chattahoochee-Flint River basin, 1990.

0 20 40 60 80 MILES

0 20 40 60 80 KILOMETERS

 EXPLANATION

WASTEWATER-DISCHARGE OUTFALL,

IN MILLION GALLONS PER DAY

SURFACE WATER

Greater than 10

1 to 10

LAND DISPOSAL

1 to 10

7

22

WASTEWATER-TREATMENT OUTFALL 

NUMBER AND FACILITY NAME

(Refer to Table 6 for more information)

 1 Cornelia WPCP

 2 Gainesville WPCP No 2

 (Linwood Drive) 

 3 Gainesville WPCP No 1

 (Flat Creek)

 4 Crooked Creek WPCP

 5 Johns Creek WPCP

 6 Big Creek WPCP

 7 R.L. Sutton WPCP

 8 R.M. Clayton WPCP

 9 South Cobb WPCP

 10 Utoy Creek WPCP

 11 South River WPCP

 12 Camp Creek WPCP

 13 Douglasville South WPCP

 14 Carroll County Water Authority

 15 Lanett WWTP

 16 Long Cane Creek WPCP

 17 East Alabama WSFPA

 18 Phenix City WWTP 

 19 Columbus South WPCP

 20 Eufaula WWTP

 21 Dothan Omusee Creek WWTP

 22 Shoal Creek WPCP

 23 Line Creek WPCP

 24 Potato Creek WPCP

 25 Bell Creek WPCP 

 26 Cordele WPCP

 27 Mill Creek WPCP

 28 Albany WPCP

 29 Camilla WPCP

 30 Bainbridge WPCP

 31 Marianna STP

30

31

33

34

84

o

o

o

85o

32o

o

o 6

5 4

3

2

1

1

21

23

25

26

27

30

29

31

14

22

8

9

1110

12

13

18

15

17

28

16

19

24

20

7

20
Figure 7. Effluent discharge from ten municipal-wastewater-treatment facilities that discharge more 

than 1 million gallons per day into the Chattahoochee River and its tributaries and population of the 

five counties where these facilities discharge, Metropolitan Atlanta, 1980–95 (written communications

from Georgia Environmental Protection Division, 1980–95, and Atlanta Regional Commission, 1996). 

1980 1982 1984 1986 1988 1990 1992 1994 1996

300

200

100

0

3

2

1

0

AVERAGE MONTHLY DISCHARGE,

IN MILLION GALLONS PER DAY

POPULATION FOR COBB, DEKALB, DOUGLAS, FULTON,

AND GWINNETT COUNTIES, IN MILLIONS

Population

Discharge

 4 Crooked Creek WPCP

 5 Johns Creek WPCP

 6 Big Creek WPCP

 7 R.L. Sutton WPCP

 8 R.M. Clayton WPCP

 9 South Cobb WPCP

 10 Utoy Creek WPCP

 11 South River WPCP (discharge location 

 moved from South River to

 Chattahoochee River in 1985)

 12 Camp Creek WPCP

 13 Douglasville South WPCP

Municipal-wastewater-treatment facilities—

 see figure 6 for discharge locations

21

Many changes in wastewater treatment and 

discharge within the ACF River basin occurred from 

1972–90. These changes affect water quality within 

the basin and include, but are not limited to:

• upgrades in treatment technology;

• increased treatment capacity; 

• consolidation of treatment facilities; 

• opening new and closing old WWTF;

• diversion of effluent disposal from 

tributaries to larger streams having more 

assimilative capacity;

• diversion of effluent disposal from the 

headwaters of the Flint River, 

Intrenchment Creek (tributary to the 

South River), and the South River (part of 

the Ocmulgee River basin) to the 

Chattahoochee River; and 

• increased use of land disposal of treated 

effluent. 

The Three Rivers Water-Quality Program was 

implemented between 1981–85 to improve water 

quality in the Flint and South Rivers by diverting 

discharges of municipal effluent from small 

headwater streams to the Chattahoochee River which 

has more assimilative capacity. Three Rivers WaterQuality Program involved three major components: 

(1) abandoning the Atlanta Flint River Water 

Pollution Control Plant (WPCP) and piping effluent 

from it to the South River WPCP, (2) linking the 

Intrenchment Creek WPCP to the South River WPCP 

to treat effluent during wet weather conditions, and 

(3) upgrading the South River WPCP and piping its 

effluent to the Chattahoochee River beginning May 

1985 (Atlanta Regional Commission, 1984, p. 40–

44).

In 1990, municipal WWTF discharged an 

estimated 2,500 tons of ammonia as nitrogen and 

1,100 tons of phosphorus into the ACF River basin 

(table 4; modified from Frick and others, 1993, p. 38). 

Nutrient load estimates for 1990 were calculated for 

25 and 14 major municipal WWTF that reported 

monthly average ammonia and phosphorus 

concentrations, respectively (table 6). The frequency 

of NPDES required nutrient testing for municipal 

facilities within the ACF River generally ranges from 

five times per week for the largest WWTF to two 

times per year for smaller WWTFs with no drinkingwater intakes downstream (James Summerville, 

Georgia Environmental Protection Division, oral 

commun., 1994). NPDES permitting at many 

facilities within the ACF River basin allows discharge 

of higher ammonia concentrations within treated 

effluent during the high-flow season (approximately 

December through May). For municipal WWTF that 

did not report nutrient concentrations in their effluent, 
22

average concentrations (based on ammoniaconcentration data for 86 percent and phosphorusconcentration data for 76 percent of effluent 

discharged within the basin in 1990; modified from 

Frick and others, 1993, p. 38) were multiplied by the 

quantity of effluent discharged by these plants in 1990 

to calculate loads. Although included in load 

estimates from WWTFs, land application of 

wastewater is a nonpoint-source input because much 

of the nutrients applied to the land surface do not 

reach the hydrologic system.

The combined annual phosphorus and ammonia 

loads from the six largest Metropolitan Atlanta area 

municipal WWTF that discharge into the Middle 

Chattahoochee subbasin declined from 1988 to 1992, 

even though the effluent discharge increased 

(Wangsness and others, 1994) (fig. 8). Phosphorus 

loads decreased from about 1,500 tons in 1988 to 

about 270 tons in 1993 because of restricted use of 

phosphate detergents and upgraded treatment of 

municipal wastewater. Amendments to the Georgia 

Water Quality Control Act in 1990, set standards 

limiting the amount of phosphorus in various 

household and commercial detergents and the average 

monthly concentration of phosphorus discharged into 

the Chattahoochee River between Buford Dam and 

West Point Lake was restricted to less than or equal to 

0.75 milligrams per liter (mg/L) beginning January 1, 

1992. This restriction applies to discharges permitted 

for 1 Mgal/d or more by the National Pollutant 

Discharge Elimination System. Ammonia loads from 

the same six Metropolitan Atlanta plants also 

decreased from about 2,690 tons in 1988 to about 720 

tons in 1992 (fig. 8), but increased to about 970 tons 

in 1993, possibly a result of continually increasing 

volumes of treated effluent from WWTF.

Nonpoint-Source Inputs

Nonpoint-source inputs have broad source areas, 

ranging in areal extent from less than a square mile to 

thousands of square miles. A small, but often 

unknown, percentage of nonpoint-source inputs of 

nutrients enters the hydrologic system by leaching, 

runoff, or deposition on water surfaces. Examples of 

nonpoint-source inputs of nutrients from natural 

sources include loss of sediment-bound phosphorus 

from forested areas, detritus from riparian vegetation, 

dissolution from nitrogen-bearing minerals in aquifer 

materials, and leaching of nitrogen from natural soil. 

No attempt was made in this report to estimate 

nutrient input to the hydrologic system from natural

NUTRIENT LOAD, IN TONS PER YEAR

Ammonia load

in effluent

3,000

2,500

2,000

1,500

1,000

500

0

1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 Voluntary restriction on use of phosphate detergents Mandatory restriction on use of phosphate detergents

Incomplete data 

set for 1985

Phosphorus load

in effluent

Effluent discharge

300

250

200

150

100

50

0

AVERAGE DISCHARGE, IN MILLIONS OF GALLONS PER DAY

Figure 8. Effluent discharge and ammonia and phosphorus loads from the six largest municipalwastewater-treatment facilities, Middle Chattahoochee-Lake Harding subbasin, 1980–93 (modified 

from Wangsness and others, 1994).
23

nonpoint sources. Nonpoint-source inputs of nutrients 

estimated in this report, which all have primarily 

anthropogenic sources, are animal manure, fertilizer, 

and atmospheric deposition. Nutrient inputs estimated 

in this report do not reflect volatilization, uptake by 

plants, nitrification, or other potential losses. 

Therefore, the reader should evaluate estimates of 

nonpoint-source inputs of nutrients as the estimated 

input to land and water surfaces, and realize that only 

some portion of that input enters surface- and groundwater resources. No attempt was made in this report 

to estimate runoff from agriculture, urban, suburban, 

and other land-use areas.

 Animal manure

Animal manure, for the purpose of this report, is 

the aggregate of manure from poultry, cows and 

calves, and hogs and pigs. Agricultural statistics 

available for much of the period from 1974–90 

indicate a substantial increase in poultry production in 

the ACF River basin—from about 92 million birds in 

1974 to about 250 million birds in 1990. During the 

same time period, there was a slight decrease in the 

numbers of cows and calves, and hogs and pigs in the 

basin (U.S. Bureau of Census, 1981a,b,c, and 

1989a,b,c; Alabama Agricultural Statistics Service, 

1991; Florida Agricultural Statistics Service, 1991a, 

b; Georgia Agricultural Statistics Service, 1990 and 

1991; Strong, 1990; Strong and others, 1990). 

Because of the large increase in poultry production, 

animal manure has become an increasingly important 

source of nutrients to the ACF River basin.

Estimates of the number of animals per county 

for 1990 were reported by the Alabama (1991), 

Florida (1991a,b), and Georgia Agricultural Statistical 

Services (1991). To facilitate the computation of 

nutrient nonpoint-source inputs from each of the three 

animal groups, a simplifying assumption was made 

that animals were distributed uniformly within each 

county. Estimates of the average weight of animals, 

the amount of manure generated per 1,000 pounds 

live weight of animals, and the average nitrogen and 

phosphorus content of manure were made using 

information reported by the Georgia Agricultural 

Statistical Service (1990, 1991) and Strong (1990). 

Estimates of tons of nutrients in manure generated per 

1,000 pounds of live weight animals do not account 

for losses from volatilization that ranges from 25 to 

80 percent for nitrogen, and from 5 to 15 percent for 

phosphorus (Kay and Hammond, 1985; McIntosh and 

others, 1992, p. 2–25). These estimates also do not 

account for variations in nutrient content when 

manure is applied to fields as a result of storage time 

and storage method. Nitrogen and phosphorus inputs 

from animal manure generated annually within each 

county were calculated by summing the results of the 

following equation for poultry, cows and calves, and 

hogs and pigs:

nitrogen or phosphorus input in tons from 

manure generated by the specified animal 

group = (number of animals in the county) 

x (percent of the county within the ACF 

River basin) x (average animal weight) x 

(tons of nitrogen or phosphorus in manure 

generated per 1,000 pounds live weight)/ 

(1,000 pounds). (1)

In 1990, the manure generated by about 250 

million chickens, 500,000 cows and calves, and 

225,000 hogs and pigs in the ACF River basin 

contained about 120,000 tons of nitrogen and 28,000 

tons of phosphorus (table 4) (Frick and others, 1993, 

p. 37). Inputs from poultry and livestock manure 

primarily are nonpoint-source inputs to the land 

surface. Poultry accounts for 89 percent of the 

nutrient input from manure in the ACF River basin. 

Poultry production in 1990 was concentrated in a fivecounty area in the headwaters of the Chattahoochee 

River (fig. 9). Agricultural land use in this five-county 

area (Upper Chattahoochee subbasin) was 

predominantly pasture land used for grazing cattle 

and for disposing poultry manure. Estimated application rates in tons per square mile (tons/mi2

) of 

nitrogen and phosphorus (fig. 9) were higher than 

application rates for other categories of nonpointsource inputs of nutrients, partly because of the large 

concentration of poultry production in a relatively 

small part of the basin.

Fertilizer

 Nitrogen and phosphorus inputs from fertilizers 

were estimated for 1990 using commercial fertilizer 

sales figures by county (Janice T. Berry, National 

Fertilizer and Environmental Research Center, 

Tennessee Valley Authority, written commun., 1993). 

An average of 1989 and 1991 fertilizer sales estimates 

were used for Georgia, because 1990 estimates are not 

available. These fertilizer sales estimates were 

generated by a combination of sales tonnages reported 

by fertilizer dealers and farm expenditures for 

fertilizer. The following uncertainties in fertilizersales data increase the uncertainty of input estimates 

for commercial fertilizer: (1) fertilizer was not 

necessarily used in the same year and county where it 

was purchased, (2) fertilized land was not evenly 

distributed within counties, and (3) Georgia, 

Alabama, and Florida used different methods to report 

non-farm sales and total sales of fertilizer.
30°

31°

33°

34°

84°

85°

32°

TOWNS UNION

 Nitrogen Phosphorus

Less than 5 Less than 1

6 to 32 1 to 8

53 to 111 12 to 25

NUTRIENT INPUTS FROM ANIMAL MANURE,

IN TONS PER SQUARE MILE

EXPLANATION

0 20 40 60 80 MILES

0 20 40 60 80 KILOMETERS

Figure 9. Nitrogen and phosphorus inputs from animal manure, by county, Apalachicola-ChattahoocheeFlint River basin, 1990 (data from Agricultural Statistics Service of Alabama, 1991, Florida, 1991a,b, and 

Georgia, 1990,1991; and Strong, 1990).

Base from U.S. Geological Survey digital files

Alabama

Florida

Alabama

Florida

Georgia

Florida

Georgia

Florida

 Alabama

Georgia

HABERSHAM

WHITE LUMPKIN

FORSYTH HALL

GWINNETT

DEKALB FULTON

COBB PAULDING

CARROLL

DOUGLAS

CLAYTON

HENRY FAYETTE

COWETA

HEARD

MONROE

PEACH

HOUSTON

PIKE LAMAR MERIWETHER

TROUP

HARRIS

MUSCOGEE

CHATTAHOCHEE

MARION

SCHLEY

MACON

DOOLY

CRISP

SUMTER WEBSTER

STEWART

QUITMAN

RANDOLPH TERRELL LEE

WORTH

MITCHELL

BAKER

DOUGHERTY CALHOUN CLAY

EARLY

MILLER

SEMINOLE

DECATUR

GADSDEN

GRADY

TALBOT

UPSON

CRAWFORD

TAYLOR

SPALDING

COLQUITT

TURNER

BAY CALHOUN

GULF FRANKLIN

JACKSON

LIBERTY

WASHINGTON

BARBOUR

BULLOCK

CHAMBERS

GENEVA

HENRY

HOUSTON

LEE

MACON

RANDOLPH

RUSSELL

DAWSON

24
25

In 1990, about 82,000 tons of nitrogen and 

20,000 tons of phosphorus were applied as fertilizer to 

lands in the ACF River basin (table 4) (Frick and 

others, 1993, p. 37). The lower part of the basin, 

predominantly the row-crop agricultural areas of the 

Middle and Lower Flint subbasins, received the 

greatest input of nitrogen and phosphorus from 

commercial fertilizer (fig. 10).

Although not apparent from figure 10, fertilizer 

applications can be substantial in urban and suburban 

areas; however, few data are available from which to 

estimate nitrogen and phosphorus inputs. Fertilizersales data above reflect total sales without regard to 

farm and non-farm use. Inclusion of fertilizer sales 

from nurseries and retail stores in urban areas varies 

from state to state. Georgia did not differentiate 

between non-farm and farm sales of fertilizer, 

Alabama reported less than one percent of fertilizer 

sales were non-farm related, and Florida reported 

more than 20 percent of fertilizer sales were non-farm 

related (Janice T. Berry, Tennessee Valley Authority, 

oral commun., 1994).

A conservative estimate of nitrogen and 

phosphorus input from fertilizer applied to urban and 

suburban lands in the ACF River basin is about 8,600 

tons/yr and 2,500 tons/yr, respectively. Fertilizer 

application rates were based on recommended 

application rates for Cobb County (Tetra Tech, 1992), 

partially within the ACF River basin in the 

northwestern part of Metropolitan Atlanta. The 

minimum estimates reported by Tetra Tech (1992) 

were converted to tons of nitrogen and phosphorus 

per square mile of urban and suburban land and 

multiplied by urban-land area listed in table 2. 

Because several assumptions were made to derive 

these estimates and data were not provided at the 

county level for all counties, the values are not 

included as part of the nutrient input listed in table 4 

and density estimates were not shown on figure 10. 

The conservative estimate of nitrogen and phosphorus 

inputs from fertilizer in urban and suburban areas 

would increase the estimate of total nutrient inputs 

from fertilizer by about 10 percent.

Atmospheric deposition

Nutrients from atmospheric deposition, unlike 

other estimated nutrient inputs, were distributed 

throughout the entire study area. The primary source 

of nitrogen in atmospheric deposition is nitrogen 

oxide emissions from combustion of fossil fuels. The 

rate of atmospheric deposition is a function of 

topography, nutrient sources, and spatial and temporal 

variations in climatic conditions.

Wet deposition of nitrogen was calculated from 

precipitation-chemistry data for ammonium (NH4

+) 

and nitrate (NO3

-

) ion concentrations collected 

weekly (Colorado State University, written commun., 

1993) at six National Atmospheric Deposition 

Program/National Trends Network (NADP/NTN) 

stations (fig. 11) in or near the ACF River basin. The 

estimate of NO3

-

 wet deposition was adjusted for 

urban effects and droplet deposition at high altitudes 

(Sisterson, 1990; L.J. Puckett, U.S. Geological 

Survey, written commun., 1993). Dry deposition of 

NO3

-

 (which was estimated to be nearly half of wet 

deposition of NO3

-

) was calculated based on wetdeposition estimates for NO3

-

, and ratios of wet and 

dry deposition for Alabama, Florida, and Georgia 

(Sisterson, 1990). Only wet-deposition estimates were 

made for NH4

+ because of lack of dry-deposition 

estimates on a national basis; therefore, input 

estimates may underestimate total nitrogen 

deposition. No attempt was made in this report to 

estimate atmospheric deposition of organic nitrogen. 

Data are not available nationally to estimate 

phosphorous input from the atmosphere; however, 

atmospheric deposition of phosphorus probably is 

minor, especially compared to nitrogen (R.P. Hooper, 

U.S. Geological Survey, oral commun., 1993).

Atmospheric deposition of nitrogen was about 

24,000 tons in 1990 calendar year (table 4) (wateryear estimate used in Frick and others, 1993, p. 38), 

which accounts for 10 percent of nitrogen inputs 

estimated in this report (table 4). For 1990, estimated 

nitrogen deposition rates were 1.2 tons/mi2

throughout the ACF River basin. This deposition rate 

was the same regardless if deposition rates were 

spatially averaged using an inverse-weighted average 

of the distance from each NADP/NTN station to a 

central point within four regions defined primarily by 

physiographic provinces or to a central point within 

the ACF River basin. Estimated annual atmospheric 

input of nitrogen to the ACF River basin from 1985 to 

1991 ranged from a low of about 22,000 tons in 1988 

to a high of about 36,000 tons in 1991. These are 

equivalent to deposition rates of 1.1 to 1.8 tons/mi2

.
30

31

33

34

84

o

o

o

85 o

32 o

o

o

 Nitrogen Phosphorus

Less than 7 Less than 1.6

7 to 15 1.6 to 3.3

15 to 24 4.2 to 6.3

NUTRIENT INPUTS FROM FERTILIZER,

IN TONS PER SQUARE MILE

EXPLANATION

0 20 40 60 80 MILES

0 20 40 60 80 KILOMETERS

Figure 10. Nitrogen and phosphorus inputs from fertilizer, by county, Apalachicola-Chattahoochee-Flint 

River basin, 1990 (data from National Fertilizer and Environmental Research Center, Tennessee 

Valley Authority). 

Base from U.S. Geological Survey digital files 

Alabama

Florida

Georgia

Florida

Georgia

Florida

Alabama

Georgia

26
NORTH

CAROLINA

SOUTH

CAROLINA

ALABAMA GEORGIA

TENNESSEE

Apalachicola–

Chattahoochee–

Flint River basin

Base from U.S. Geological Survey digital files

86° 84° 82° 80°

34°

32°

30° FLORIDA

0

0 40 80 120 160 KILOMETERS

40 80 120 160 MILES

Sand Mountain

Experiment Station

Georgia

Experiment

Station

Black Belt

Substation

Tifton Agricultural

Research Service

Quincy

Coweeta

Figure 11. Location of National Atmospheric Deposition Program precipitation stations used to estimate

nitrogen input from atmospheric deposition within the Apalachicola–Chattahoochee–Flint River basin.

27

ANALYSIS OF NUTRIENT

WATER-QUALITY DATA

The emphasis of the analysis of nutrient waterquality data section of this report is to present 

graphical and statistical analyses describing regional 

variations in the presence, distribution, and transport 

of nutrients in surface and ground water of the ACF 

River basin. Nutrient water-quality standards, health 

advisories, and criteria are presented to help put 

nutrient concentrations in context. Brief descriptions 

of sources of nutrient water-quality data and the 

assessment approached used are also included.

Nutrient Water-Quality Standards,

Health Advisories, and Criteria

Nitrate and nitrate plus nitrite have maximum 

contaminant levels (MCL) in drinking water of 10 

mg/L as nitrogen (U.S. Environmental Protection 

Agency, 1990, 1995). Drinking water with more than 

10 mg/L nitrate poses the most threat to infants 

because the reduction of nitrate to nitrite in their 

intestinal systems may prevent the transport of 

sufficient oxygen in their bloodstream (“blue baby 

syndrome” or methemoglobinemia). The draft lifetime health advisory for ammonia in adults is 30 mg/L 

as N (U.S. Environmental Protection Agency, 1995). 
28

Criteria for maximum ammonia concentrations in 

surface water are based on chronic and acute exposure 

of aquatic organisms to un-ionized ammonia (NH3). 

These criteria vary with pH and temperature and 

currently are only available for surface waters with 

pH between 6.5 and 9.0 and temperature between 0 

and 30 o C. In general, the criteria for ammonia are 

exceeded at lower concentrations as pH and 

temperature increase. At temperatures warmer than 20 o C, criteria are slightly more restrictive for surface 

waters where cold water species such as trout are 

present (Upper Chattahoochee River basin) than 

where cold water species are absent (Lower 

Chattahoochee, Flint, and Apalachicola River basins). 

Chronic criteria for total-ammonia (NH3 plus NH4

+) 

concentrations range from a maximum of 2.1 mg/L as 

N for surface waters with a pH of 6.5 and temperature 

of 0 o C, to 0.07 mg/L as N for surface waters with 

cold water species of fish present and a pH of 9.0 and 

temperature of 30 o C (U.S. Environmental Protection 

Agency, 1986).

National criteria have not been established for 

concentrations of phosphorus compounds in water; 

however, the USEPA makes the following 

recommendations to control eutrophication:

• total phosphorus should not exceed 

0.05 mg/L (as P) where a stream enters a 

lake or reservoir, and

• total phosphorus should not exceed 

0.1 mg/L in flowing waters that do not 

discharge directly into lakes or 

impoundments (U.S. Environmental 

Protection Agency, 1986).

Sources of Nutrient Water-Quality Data

A large amount of nutrient water-quality data 

have been collected within the ACF River basin by 

Federal, State, and local governments, colleges and 

universities, and other organizations. These waterquality data were collected to meet diverse objectives 

over varying temporal and spatial scales. Data 

reviewed and analyzed for this report were from 

readily available computerized data bases, except for 

discharge and concentration data from major WWTF, 

which in some cases, were computerized from paper 

files. No attempt was made to computerize data from 

other paper files or reports.

Computerized data bases used were USGS 

NWIS, USEPA STORET, and FLDER GWIS. Waterquality data collected or analyzed by the USGS were 

obtained from NWIS. STORET contains some, but 

not all, data collected by USEPA; USEPA contractors; 

other Federal agencies; and many State agencies that 

deal with natural resources and environmental 

regulation. Almost all water-quality data from GEPD 

and ADEM were stored in STORET. FLDER 

surface-water-quality data were obtained from 

STORET and ground-water-quality data were 

obtained from GWIS.

Assessment Approach

Although available nutrient water-quality data for 

the ACF River basin are not ideally suited to a 

comprehensive water-quality assessment, the data can 

be used to make preliminary assessments of presence, 

distribution, and transport of nutrients within the 

study area. Common limitations of existing nutrient 

water-quality data that can bias water-quality 

assessments include:

• unknown or limited information on 

quality-control procedures related to 

sample collection, laboratory analysis, 

and data storage;

• varying or unknown sampling, 

preservation, and analytical techniques 

used among and, in some cases, within 

agencies;

• varying accuracy of reported sampling 

locations; 

• uneven areal, vertical, and temporal 

distribution; 

• clustering of samples around known or 

suspected contamination or event 

sampling;

• missing information on flow conditions 

and sample type (grab, composite, depth 

integrated) for surface-water samples; and

• lack of data on well construction, 

sampling depth, water level, and aquifer 

characteristics for ground-water samples.

Grab samples may provide biased results if 

concentrations of dissolved and suspended 

constituents are not homogeneous in the cross section 

at the sampling sites. Limitations that primarily affect 

load and trend calculations, and subsequent 

comparisons among surface-water sites include: 

(1) varying sampling frequencies, (2) different 

periods of record, and (3) insufficient sampling of 

high flow events, the hydrologic condition during 

which a major percentage of transport occurs for 

many nutrient species.

Graphical and nonparametric statistical methods 

were used to analyze the nutrient data in this report. 

Nonparametric statistical methods use ranks of the 
29

data rather than the data themselves, involve robust 

techniques that are less sensitive to extreme values 

than standard parametric statistics, do not require 

artificial substitutions for censored data, and do not 

require assumptions about the distribution or variance 

of the data. Analyses of water-quality data are better 

suited to nonparametric than parametric statistical 

methods because distributions of water-quality data 

are rarely known, but are often log-normally 

distributed and may vary among constituents, time 

periods, and locations (Helsel, 1990, p. 1769).

Data compilation and screening

The three computerized data bases used in this 

report store water-quality data by parameter codes. 

Data stored by many of these parameter codes are 

similar enough that, for the purposes of this report, 

data were reformatted and combined to reduce the 

number of nutrient constituent groups analyzed and to 

increase spatial and temporal distribution of available 

data for each nutrient constituent group analyzed. Six 

constituent groups for nitrogen (total nitrogen, totalinorganic nitrogen, total-organic nitrogen, dissolved 

ammonia, dissolved nitrate, and dissolved-organic 

nitrogen) and two constituent groups for phosphorus 

(total phosphorus and dissolved orthophosphate) were 

created by using algorithms to reformat and combine 

data stored by similar parameter codes within and 

among the three computerized data bases (table 7). 

Algorithms used to transform source data into 

selected nutrient constituent groups included (1) 

converting concentrations reported in radical form to 

elemental form (such as PO4 to as P), (2) converting 

to consistent units of measure (such as from μg/L to 

mg/L), (3) assuming the predominant form of a 

nutrient species for some constituent groups (such as 

assuming most ammonia is dissolved so that total 

ammonia is a reasonable approximation of dissolved 

ammonia), and (4) adding or subtracting data stored in 

two or more parameter codes to estimate the 

concentration of a nutrient species that was not 

directly measured (such as total nitrogen equals 

ammonia plus organic nitrogen plus nitrate plus 

nitrite).

For each of the eight constituent groups, a single 

censoring limit had to be selected so data could be 

ranked. This censoring limit, listed in table 7, was 

either the highest analytical reporting limit or the 

most common analytical reporting limit. All nutrient 

analyses with reported values smaller than the 

censoring limit were changed to “less than” the 

censoring limit, and the few analyses with “less-than” 

values larger than the censoring limit were changed to 

missing values.

Nutrient analyses stored in more than one data 

base were combined to eliminate duplicates. 

Unusually high or low concentrations (outliers) were 

checked against published reports and original data 

bases. If typographical errors were obvious, values 

were corrected; otherwise, all outliers were included 

in graphical and statistical analyses. Because of the 

lack of information on sample collection purpose, 

attempts were not made to omit data collected as part 

of local contamination assessment studies. Data 

known to be from intensive sampling over a short 

period of time and not representative of the 1972–90 

period of interest were not used for some graphical 

and statistical analyses.

Nutrient data from 1972–90 for any individual 

well or spring in the study area were insufficient for 

trend analyses. To eliminate spatial bias of data from 

wells and springs having multiple-nutrient samples, 

the median concentration for each well and spring 

was used for each nutrient constituent group.

Nutrient data from 1972–90 water years for the 

ACF River basin are summarized in table 8 by 

nutrient constituent group, by agency, and by source 

of water (streams, reservoirs and lakes, wells, and 

springs). In surface water, total phosphorus, dissolved ammonia, dissolved nitrate, and totalinorganic nitrogen have the most available nutrient 

data. Ground-water-nutrient data are much more 

limited, in terms of collecting agencies, spatial and 

temporal distribution, and nutrient constituents. Most 

available ground-water-nutrient data were dissolvednitrate concentrations.

Distribution of sampling sites

Temporal distribution of nutrient water-quality 

samples from surface water (streams, and reservoirs 

and lakes) and ground water (wells and springs) for 

1972–90 water years are shown in figure 12. The 

increase in the number of nutrient samples collected 

from streams in 1976–77 was primarily the result of 

the USGS Upper Chattahoochee River Quality 

Assessment (Cherry and others, 1980). The increase 

in the number of nutrient samples collected in 

reservoirs and lakes in 1978–79 primarily was the 

result of several Water Quality Management Studies 

funded by the U.S. Army Corps of Engineers (Diane 

Findley, U.S. Army Corps of Engineers, oral 

commun., 1994). The increase in the number of 

nutrient samples collected in wells from 1985 to 1990 

was the result of statewide ground-water-monitoring 

programs in Georgia and Florida.
30

Table 7. Summary of algorithms used to transform source data collected in the Apalachicola–Chattahoochee–Flint River basin into selected constituent groups[mg/L, milligrams per liter; μg/L, microgram per liter; mg/kg, milligram per kilogram; N, nitrogen; NO2, nitrite; NO3, nitrate; NH3, ammonia; P, phosphoru

Selected nutrient constituent 

groups

(censoring limit, mg/L)

Constituents from source data bases1/

Algorithm used to transform data 

Parameter name Parameter code

Dissolved ammonia Nitrogen, ammonia, dissolved (mg/L as N) 00608 Use if available.

(0.02) Nitrogen, ammonia, dissolved (mg/L as NH3) 71846 If p00608 is null, then use p71846 x 0.77648

Nitrogen, ammonia, total (mg/L as N) 00610 If p00608 and p71846 are null, then use p006Nitrogen, ammonia, total (mg/L as NH3) 71845 If p00608, p71846, and p00610 are null, then 

p71845 x 0.776486.

Ammonia, un-ionized (mg/L as N) 00619 If p00608, p71846, p00610, and p71845 are n

p00619 x 0.822443.

Ammonia, un-ionized, total (mg/L as N) 00612 If p00608, p71846, p00610, p71845, and p00

Total-organic nitrogen Nitrogen, organic, total (mg/L as N) 00605 Use if available.

(0.1) Nitrogen, ammonia plus organic, total (mg/L as N) -

dissolved ammonia

 00625 -

 dissolved ammonia

If p00605 is null, then use p00625 - dissolved 

Total nitrogen Nitrogen, total (mg/L as N) 00600 Use if available.

(0.12) Nitrogen, ammonia plus organic, total (mg/L as N) +

Nitrogen, nitrite plus nitrate, total (mg/L as N)

 00625 + 00630 If p00600 is null, then use p00625 + p00630.

(Nitrogen, nitrite, total (mg/L as N) or Nitrogen, nitrite, total (mg/L as NO2) orNitrogen, nitrite, dissolved (mg/L as N) orNitrogen, nitrite, dissolved (mg/L as NO2)) +(Nitrogen, nitrate, total (mg/L as N) orNitrogen, nitrate, total (mg/L as NO3) orNitrogen, nitrate, dissolved (mg/L as N) orNitrogen, nitrate, dissolved (mg/L as NO3))

 (00615 or 71855 or  00613 or 71856) +  (00620 or 71850 or 00618 or 71851)

If p00630 is null, then substitute one of the fo

p00630:

(p00615 or (p71855 x 0.304457) or p00613 (p00620 or (p71850 x 0.225897) or p00618 

Nitrogen, inorganic (NO2 + NO3 + NH3), total (mg/L as N) - 

dissolved ammonia

 00640 - 

 dissolved ammonia

p00640 - dissolved ammonia or

Nitrogen, nitrite plus nitrate, dissolved (mg/L as N) 00631 p00631 orNitrogen, nitrate, total (mg/L as N) or Nitrogen, nitrate, total (mg/L as NO3) orNitrogen, nitrate, dissolved (mg/L as N) orNitrogen, nitrate, dissolved (mg/L as NO3)

 00620 or 71850 or

 00618 or 71851

p00620 or (p71850 x 0.225897) or p00618 or 

Nitrogen, nitrite, total (mg/L as N) or Nitrogen, nitrite, total (mg/L as NO2) orNitrogen, nitrite, dissolved (mg/L as N) orNitrogen, nitrite, dissolved (mg/L as NO2)

 00615 or 71855 or

 00613 or 71856

p00615 or (p71855 x 0.304457) or p00613 or 
31

Nitrogen, inorganic (NO2 + NO3 + NH3), total (mg/L as N) + total-organic nitrogen

00640 + 

 total-organic nitrogen

If total nitrogen is null, then substitute p006total-organic nitrogen.

Total-inorganic nitrogen Nitrogen, inorganic, total (mg/L as N) 00640 Use if available.

(0.04) Nitrogen, nitrite plus nitrate, total (mg/L as N) + 

dissolved ammonia

 00630 +

dissolved ammonia

If p00640 is null, then use p00630 (or its subtotal nitrogen) + dissolved ammonia.

Dissolved-organic

 nitrogen 

(0.1)

Nitrogen, ammonia plus organic, dissolved (mg/L as N) - dissolved ammonia

 00623 - 

dissolved ammonia

Use if available.

Dissolved nitrate Nitrogen, nitrate, dissolved (mg/L as N) 00618 Use if available.

(0.01) Nitrogen, nitrite plus nitrate, dissolved (mg/L as N) -

Nitrogen, nitrite, dissolved (mg/L as N)

 00631 - 00613

If p00618 is null, then use p00631 - p00613.

Nitrogen, nitrite plus nitrate, dissolved (mg/L as N) 00631 If dissolved nitrate is null, then use p00631.Nitrogen, nitrite plus nitrate, total (mg/L as N) -Nitrogen, nitrite, total (mg/L as N)

 00630 - 00615

If dissolved nitrate is null, then use p00630 

Nitrogen, nitrate, total (mg/L as N) 00620 If dissolved nitrate is null, then use p00620.Nitrogen, nitrite plus nitrate, total (mg/L as N) 00630 If dissolved nitrate is null, then use p00630.Nitrogen, inorganic, total (mg/L as N) - dissolved ammonia 00640 -

dissolved ammonia

If dissolved nitrate is null, then use p00640 

Total phosphorus Phosphorus, total (mg/L as P) 00665 Use if available.

(0.02) Phosphorus total (mg/L as PO4) 71886 If p00665 is null, then use p71886 x 0.32613

Phosphate, total (mg/L as PO4) 00650 If p00665 and p71886 are null, then use p006Phosphate, poly, total (mg/L as PO4) 00655 If p00665, p71886, and p00650 are null, then Phosphorus (P), water, total recoverable μg/L 00662 If p00665, p71886, p00650, and p00655 are nPhosphate, total, colorimetric method (mg/L as P); water, total 70505 If p00665, p71886, p00650, p00655, and p00Phosphorus orthophosphate, total (mg/L as P) 70507 If p00665, p71886, p00650, p00655, p00662

p70507.

Dissolved orthophosphate Phosphorus, orthophosphate, dissolved (mg/L as P) 00671 Use if available.

(0.02) Phosphate, ortho, soluble, (mg/L as PO4); water, total 71889 If p00671 is null, then use p71889 x 0.32613

Phosphate, dissolved (mg/L as PO4) 00653 If p00671 and p71889 are null, then use p006Phosphate, ortho, dissolved (mg/L as PO4) 00660 If p00671, p71889, and p00653 are null, then Phosphorus, dissolved (mg/L as P) 00666 If p00671, p71889, p00653, and p00660 are n

Table 7. Summary of algorithms used to transform source data collected in the Apalachicola –Chattahoochee – Flint River basin into selected 

constituent groups—Continued 

[mg/L, milligrams per liter; μg/L, microgram per liter; mg/kg, milligram per kilogram; N, nitrogen; NO2, nitrite; NO3, nitrate; NH3, ammonia; P, phosphoru

Selected nutrient constituent 

groups

(censoring limit, mg/L)

Constituents from source data bases1/

Algorithm used to transform data 

Parameter name Parameter code
32

Data available for the 

ApalachicolaChattahoochee-Flint River basin, but not 

used is this report

Nitrogen, dissolved (mg/L as N) 00602 Not used.Nitrogen, organic, dissolved (mg/L as N) 00607 Not used.Nitrogen, ammonia plus organic, suspended, total (mg/L as N) 00624 Not used.Nitrogen, ammonia plus organic, dissolved, one determination 

(mg/L as N)

00636 Not used.

Total ammonia nitrogen, 30 day, total (mg/L as N) 00609 Not used—30-day statistic.Total Kjeldahl nitrogen, 30 day, total (mg/L as N) 00622 Not used—30-day statistic.Phosphorous, total, 30 day, (mg/L as P) 00664 Not used—30-day statistic.Nitrogen, ammonia total in bottom material, dry weight (mg/kg as N) 00611 Not used—bottom material.Nitrogen, ammonia plus organic total in bottom material, dry weight 

(mg/kg as N)

00626 Not used—bottom material.

Nitrogen, nitrite plus nitrate total in bottom material, dry weight 

(mg/kg as N)

00633 Not used—bottom material.

Nitrogen, Kjeldahl in total bottom material dry weight mg/kg 00627 Not used—bottom material.Phosphorus, total in bottom material, dry weight (mg/kg as P)) 00668 Not used—bottom material.

1/U.S. Geological Survey, National Water Information System (NWIS); U.S. Environmental Protection Agency, Storage and Retrieval data base (STORET); Florida Depar

Ground Water Information System (GWIS)

Table 7. Summary of algorithms used to transform source data collected in the Apalachicola –Chattahoochee – Flint River basin into selec

constituent groups—Continued 

[mg/L, milligrams per liter; μg/L, microgram per liter; mg/kg, milligram per kilogram; N, nitrogen; NO2, nitrite; NO3, nitrate; NH3, ammonia; P, phosph

Selected nutrient constituent 

groups

(censoring limit, mg/L)

Constituents from source data bases1/

Algorithm used to transform d

Parameter name Parameter code
33

Table 8. Compilation of the number of sites and nutrient analyses from Federal and State sources of digital data, by media type, Apalachico

River basin, 1972–90 water years

[–, no available data; USGS, U.S. Geological Survey; USACOE, U.S. Army Corps of Engineers; USEPA, U.S. Environmental Protection Agency; USFS, U

Georgia Environmental Protection Division; FLDER, Florida Department of Environmental Regulation; FGFWFC, Florida Game and Fresh Water Fish Co

Department of Environmental Management]

Nutrient constituent

USEPA USACOE USFS USGS FLDER FGFWFC GEPD A

Number 

of

sites

Number 

of 

analyses

Number 

of

sites

Number 

of 

analyses

Number 

of

sites

Number 

of 

analyses

Number 

of

sites

Number 

of 

analyses

Number 

of

sites

Number 

of 

analyses

Number 

of

sites

Number 

of 

analyses

Number 

of

sites

Number 

of 

analyses

Numbe

of

sites

Streams

TOTAL–sites and 

analyses

104 893 4 83 15 198 192 2,308 81 502 38 309 134 7,672 2

Total nitrogen 66 814 4 76 6 48 171 1,956 34 217 – – 17 530 2Total-inorganic 

nitrogen

67 837 4 58 1 1 180 2,161 78 460 38 299 124 5,940 1

Total-organic nitrogen 66 805 4 59 4 18 171 2,005 35 210 – – 16 516 1Dissolved ammonia 67 838 4 58 5 6 183 2,240 79 470 38 304 132 6,481 1Dissolved nitrate 104 875 4 83 6 13 185 2,223 75 483 38 304 124 6,586 2Dissolved-organic 

nitrogen

– – – – – – 61 809 – – – – – – 

Total phosphorus 71 851 4 82 15 197 189 2,181 81 495 38 302 127 7,550 2Dissolved 

orthophosphate

99 833 4 82 – – 73 1,268 11 62 38 301 7 67 

Reservoirs and Lakes

TOTAL–sites and 

analyses 28 365 51 659 8 33 36 666 11 164 10 88 49 2,420 2

Total nitrogen 19 281 51 389 2 10 11 312 6 55 – – 20 497 2Total-inorganic 

nitrogen

20 353 49 572 6 13 35 475 10 131 10 84 45 2,261 2

Total-organic nitrogen 19 280 51 324 1 5 11 465 6 50 – – 18 431 2Dissolved ammonia 20 352 49 572 6 13 35 659 10 132 10 85 45 2,265 2Dissolved nitrate 28 319 51 613 8 23 35 468 10 136 10 87 49 2,308 2Dissolved-organic 

nitrogen

– – – – – – 22 122 – – – – – – 

Total phosphorus 28 360 51 651 8 33 16 487 11 163 10 85 49 2,399 2Dissolved 

orthophosphate

18 219 51 655 – – 30 630 5 17 10 86 16 287 1
34

Wells

TOTAL–sites and 

analyses

– – – – – – 127 161 30 49 – – 43 152 4 

Total nitrogen – – – – – – 37 38 – – – – – – 2 Total-inorganic 

nitrogen

– – – – – – 52 54 – – – – – – 3 

Total-organic nitrogen – – – – – – 22 22 – – – – – – 2 Dissolved ammonia – – – – – – 62 64 – – – – – – 3 Dissolved nitrate – – – – – – 121 151 30 49 – – 43 152 4 Dissolved-organic 

nitrogen

– – – – – – 32 33 – – – – – – – 

Total phosphorus – – – – – – 24 24 27 33 – – – – 4 Dissolved 

orthophosphate

– – – – – – 54 57 4 13 – – – – – 

Springs

TOTAL–sites and 

analyses

– – – – – – 14 16 – – – – – – 2 

Total nitrogen – – – – – – 2 2 – – – – – – 1 Total-inorganic 

nitrogen

– – – – – – 2 3 – – – – – – 1 

Total-organic nitrogen – – – – – – 1 1 – – – – – – 2 Dissolved ammonia – – – – – – 2 3 – – – – – – 2 Dissolved nitrate – – – – – – 14 16 – – – – – – 1 Dissolved-organic 

nitrogen

– – – – – – 1 1 – – – – – – – 

Total phosphorus – – – – – – 1 2 – – – – – – 1 Dissolved 

orthophosphate

– – – – – – 1 1 – – – – – – – 

1/Less than the sum of the number of sites from each agency because of duplicate sites.

Table 8. Compilation of the number of sites and nutrient analyses from Federal and State sources of digital data, by media type, Apalachico

River basin, 1972 – 90 water years—Continued

[–, no available data; USGS, U.S. Geological Survey; USACOE, U.S. Army Corps of Engineers; USEPA, U.S. Environmental Protection Agency; USFS, U

Georgia Environmental Protection Division; FLDER, Florida Department of Environmental Regulation; FGFWFC, Florida Game and Fresh Water Fish CoDepartment of Environmental Management]

Nutrient constituent

USEPA USACOE USFS USGS FLDER FGFWFC GEPD A

Number 

of

sites

Number 

of 

analyses

Number 

of

sites

Number 

of 

analyses

Number 

of

sites

Number 

of 

analyses

Number 

of

sites

Number 

of 

analyses

Number 

of

sites

Number 

of 

analyses

Number 

of

sites

Number 

of 

analyses

Number 

of

sites

Number 

of 

analyses

Numbe

of

sites
Figure 12. Number of nutrient water-quality samples analyzed from streams, reservoirs and lakes, 

wells, and springs, Apalachicola-Chattahoochee-Flint River basin, 1972-90 water years.

72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90

NUMBER OF NUTRIENT WATER-QUALITY SAMPLES

WATER YEAR

1,500

1,000

500

0

60

50

40

30

20

10

0

Streams Reservoirs and lakes

Wells Springs

35

Spatial distribution of nutrient sampling sites by 

collection agency for 1972–90 water years are shown 

in figure 13 for streams, and reservoirs and lakes, and 

figure 14 for wells and springs. The number of 

nutrient analyses at each surface-water site, the 

temporal distribution and frequency of those analyses, 

and the availability of ancillary data, such as 

instantaneous and mean daily streamflow, determined 

the types of graphical and statistical analyses that 

were done with data from each site. Graphical and 

statistical analyses, number of nutrient analyses, and 

number of sites used for each are listed in table 9.

Nutrients in Surface Water

Nutrients in surface waters of the ACF River 

basin are of concern because high concentrations 

and(or) loads can be toxic to aquatic organisms and 

cause eutrophication of streams, lakes, and reservoirs 

within the basin. Nutrient outflow from the basin 

affects the biological productivity in Apalachicola 

Bay, Fla., through changes in the amount and seasonal 

patterns of nutrient loading to the Bay. The distribution and transport of nutrients in surface water within 

the ACF River basin are influenced by many factors 

including watershed characteristics and nutrient 

sources described in earlier sections of this report.

Reservoirs modify streamflow characteristics by 

converting riverine environments to lacustrine 

environments, particularly along the mainstem of the 

Chattahoochee River. Although ranges of nutrient 

concentrations for eight nutrient constituent groups 

measured from 1972–90 in streams (fig. 15a) are 

similar to ranges measured in reservoirs and lakes 

(fig. 15b), reservoirs potentially have a large influence 

on the distribution and transport of nutrients in 

surface water within the study area.
30

31

33

34

84

o

o

o

85 o

32o

o

o

U.S. Geological

 Survey

30

31

33

34

84

o

o

o

85 o

32o

o

o

U.S. Forest 

Service

30

31

33

34

84

o

o

o

85 o

32o

o

o

U.S. Environmental 

Protection Agency

30

31

33

34

84

o

o

o

85 o

32o

o

o

U.S. Army Corps 

of Engineers

EXPLANATION

STREAM WATER-SAMPLING SITE

 HAVING NUTRIENT DATA

RESERVOIR OR LAKE WATER-

 SAMPLING SITE HAVING

 NUTRIENT DATA

Base from U.S. Geological Survey digital files

Figure 13. Distribution of stream, reservoir, and lake water-sampling sites having nutrient data, by

collection agency, Apalachicola-Chattahoochee-Flint River basin, 1972-90 water years.

36
30

31

33

34

84

o

o

o

85 o

32o

o

o

Florida Game and Freshwater

Fish Commission

30

31

33

34

84

o

o

o

85 o

32o

o

o

Florida Department of

Environmental Regulation

30

31

33

34

84

o

o

o

85 o

32o

o

o

Georgia 

Environmental

Protection

Division

30

31

33

34

84

o

o

o

85 o

32o

o

o

Alabama 

Department of 

Environmental

Management

Base from U.S. Geological Survey digital files

Figure 13. Distribution of stream, reservoir, and lake water-sampling sites having nutrient data, by

collection agency, Apalachicola-Chattahoochee-Flint River basin, 1972-90 water years—Continued.

EXPLANATION

STREAM WATER-SAMPLING SITE 

 HAVING NUTRIENT DATA

RESERVOIR OR LAKE WATER-

 SAMPLING SITE HAVING

 NUTRIENT DATA

37
U.S. Geological

 Survey

Georgia Geologic

 Survey

Florida Department of 

Environmental Regulation

Alabama Department of 

Environmental Management

EXPLANATION

WELL

SPRING

Base from U.S. Geological Survey digital files

Figure 14. Distribution of ground-water sampling sites having nutrient data, by collection agency, 

Apalachicola-Chattahoochee-Flint River basin, 1972-90 water years.

30

31

33

34

84

o

o

o

85o

32o

o

o

30

31

33

34

84

o

o

o

85o

32o

o

o

30

31

33

34

84

o

o

o

85o

32o

o

o

30

31

33

34

84

o

o

o

85o

32o

o

o

38
39

Table 9. Summary of graphical and statistical analyses of nutrient data, by media type, Apalachicola–Chattahoochee–Flint River basin, [–, no available data; >, greater than; Sources of data: USEPA, U.S. Environmental Protection Agency; USACOE, U.S. Army Corps of Engineers; USFS, U.S. Forest Service; USGS, U.S. Geological Survey; FLDER, Florida Department of Environmental Regulation; FGFWFC, Florida Game and Fresh Water Fish Commission GEPD, Georgia Environmental Protection Division; ADEM, Alabama Department of Environmental Management; GGS, Georgia Geologic Survey]

Type of graphical or 

statistical analysis Sources of data

Period of 

record(water 

years)

Minimum 

number of 

samples per 

site

Number of nutrient analyses and sites (number of sites in 

Total 

nitrogen

Totalinorganic 

nitrogen

Totalorganic 

nitrogen

Dissolved 

ammonia

Dissolved 

nitrate

Dissolvedorganic 

nitrogen

pho

Streams

Spatial distribution and graphical 

summary (boxplots) of 

concentrations by constituent groups (figure 15a)

USEPA, USACOE, 

USFS, USGS, 

FLDER, FGFWFC, 

GEPD, ADEM

1972–90 1 3,675

(326)

9,817

(510)

3,671

(314)

10,457

(526)

10,948

(565)

809

(61)

Relation of concentration to stream 

discharge (figures 17–20)

USGS, GEPD 1972–90 25 — — — 2,401

1/(13)

2,470

1/(13)

— 

Graphical summary (boxplots) of 

concentrations by river mile 

(figures 22–29)

USGS, GEPD, 

ADEM, FLDER

1972–90 15 1,067

(15)

5,253

(33)

1,057

(15)

5,314

(33)

5,499

(34)

197

(5)

Seasonal variation (figures 30–35) USGS, GEPD 1972–90 25 — — — 2,034

(11)

2,084

(11)

— 

Temporal trends (figures 36–42; 

table 15)

USGS, GEPD2/, 

FLDER

1980–90 3/32 664

(11)

3,667

(34)

640

(10)

3,947

(34)

4,073

(34)

— 

Annual loads (figures 43–45; 

table 16)

USGS, GEPD, 

FLDER

1972–90 4/40 906

(13)

4,358

(26)

893

(13)

4,411

(26)

4,493

 (26)

— 

Reservoirs and Lakes

Spatial distribution and graphical 

summary (boxplots) of 

concentrations by constituent groups (figure 15b)

USEPA, USACOE, 

USFS, USGS, 

FLDER, FGFWFC, 

GEPD, ADEM

1972–90 1 1,717

(131)

4,061

(213)

1,726

(128)

4,249

(197)

4,136

(197)

122

(22)

Graphical summary (boxplots) of 

concentrations by river mile 

(figures 22–29)

USGS, GEPD 1972–90 15 1,610

5/(5)

3,787

5/(6)

1,626

5/(5)

3,974

5/(6)

3,842

5/(7)

122

5/(2)

Seasonal variation (figures 30–35) USGS, GEPD 1972–90 25 — — — 1,163

(6)

1,191

(6)

— 

Temporal trends (figures 36–42; 

table 15)

USGS, GEPD 1980–90 3/32 241

(5)

762

(6)

219

(5)

764

(6)

800

(6)

— 
40

Wells6/

Spatial distribution and graphical 

summary (boxplots) of 

concentrations by constituent groups (figure 47a)

USGS, ADEM, 

FLDER, GGS

1972–90 1 38

(38)

53

(53)

23

(23)

63

(63)

185

(185)

32

(32)

Graphical summary (boxplots) of 

concentrations by aquifer 

(figure 49)

USGS, ADEM, 

FLDER, GGS

1972–90 1 — — — 62

(62)

182

(182)

— 

Graphical summary (boxplots) of 

concentrations by water use 

(figure 50)

USGS, ADEM, 

FLDER, GGS

1972–90 1 — — — 56

(56)

176

(176)

— 

Springs6/

Spatial distribution and graphical 

summary (boxplots) of 

concentrations by constituent groups (figure 47b)

USGS, ADEM 1972–74, 

1982–83, 1985–87

1 3

(3)

3

(3)

3

(3)

4

(4)

15

(15)

1

(1)

1/ Data were analyzed from 13 sites; however, only 11 are present among figures 17 to 20.2/ Includes data collected by DeKalb County, Georgia, and obtained from Georgia Environmental Protection Division.3/ Minimum of eight years of quarterly data.5/ Samples collected from all sampling sites within a given reservoir are shown in a single boxplot for that reservoir in figures 22 to 29; sampling sites in 

between the Chattahoochee River arm and the Flint River arm of the reservoir. 

6/ If more than one nutrient analysis was available for a well or spring, then to reduce spatial bias, the median nutrient concentration was used.

Table 9. Summary of graphical and statistical analyses of nutrient data, by media type, Apalachicola – Chattahoochee – Flint River basin, 

Continued

[–, no available data; >, greater than; Sources of data: USEPA, U.S. Environmental Protection Agency; USACOE, U.S. Army Corps of Engineers; USFS, U.S. Forest Service; 

USGS, U.S. Geological Survey; FLDER, Florida Department of Environmental Regulation; FGFWFC, Florida Game and Fresh Water Fish Commission

Type of graphical or 

statistical analysis Sources of data

Period of 

record(water 

years)

Minimum 

number of 

samples per 

site

Number of nutrient analyses and sites (number of sites in p

Total 

nitrogen

Totalinorganic 

nitrogen

Totalorganic 

nitrogen

Dissolved 

ammonia

Dissolved 

nitrate

Dissolvedorganic 

nitrogen

T

pho
41

10

1

0.10

0.01

Streams Reservoirs and lakes

Total nitrogen

Total inorganic nitrogen

Total organic

nitrogen

Dissolved ammonia

Dissolved nitrate

Dissolved

organic nitrogen

Total phosphorus

Dissolved

orthophosphate

Total nitrogen

Total inorganic nitrogen

Total organic

nitrogen

Dissolved ammonia

Dissolved nitrate

Dissolved

organic nitrogen

Total phosphorus

Dissolved

orthophosphate

3,765

9,817

3,671

10,457 10,948 809 12,007

2,619

3,671

1,717

4,061

1,726

4,249

4,136

122

4,361

1,990

Number of analyses 

90

75

50

25

10

Censoring limit

Percentile

EXPLANATION

Figure 15. Distribution of nutrient concentrations in streams and reservoirs and lakes by nutrientconstituent groups, Apalachicola-Chattahoochee-Flint River basin, 1972–90 water years. CONCENTRATION, IN MILLIGRAMS PER LITER

From 1972–90, nitrate concentrations in surfacewater samples from the ACF River basin did not 

exceed the USEPA MCL of 10 mg/L nitrate as N in 

drinking water. However, total-phosphorus concentrations in more than 40 percent of the surface-water 

samples exceeded the USEPA recommendation of 

0.1 mg/L total phosphorus, a concentration threshold 

established to control eutrophication in flowing 

waters. About 70 percent of surface-water samples 

exceeded the USEPA more restrictive recommendation of 0.05 mg/L total phosphorus, a concentration 

threshold recommended to control eutrophication 

where streams enter a lake or reservoir. About one 

percent of dissolved-ammonia concentrations in 

surface-water samples exceeded 2.1 mg/L as N, a 

concentration USEPA based on chronic exposure of 

aquatic organisms to un-ionized ammonia for most 

natural surface waters.

Graphical and statistical analyses of nutrients in 

surface water in the rest of this report are limited to 

sampling sites where 15 or more nutrient samples 

were collected during 8 or more years from 1972–90 

(table 10, fig. 16). In addition to nutrient sampling 

sites, many gaging stations that are close enough to 

reasonably approximate streamflow at sampling sites 

are included in table 10 and figure 16. Streamflow 

data collected at these sites are used in trend and(or) 

load estimations. Characteristics such as river miles, 

drainage area, mean annual flow and runoff, provide 

information to help put nutrient data in context to the 

hydrologic flow system at each sampling site. Lowflow statistics, such as the 7-day, 10-year low flow of 

a stream, also are listed because they are often used as 

measures of dependable flow during periods of 

moderate drought and in permitting waste discharges. 

Location numbers in table 10 and figure 16 are used 

throughout the remaining surface-water tables and 

figures.

Relation of concentration to stream discharge

In general, as stream discharge increases at a 

specific location, concentration of constituents 

associated with point-source loads decreases in the 

stream because of dilution resulting in a negative 

relation between concentration and discharge. In 

contrast, concentration of constituents associated with 

nonpoint-source inputs generally increase as 

discharge increases because of runoff and stormwaterdrain flow resulting in a positive relation between 

concentration and discharge. These very simplified 

relations between concentration and discharge are 

effected by many factors including antecedent
42

Table 10. Streamflow and basin characteristics for surface-water sites where data were used in nutrient analyses, by subbasin, Apalachicola–

basin, 1990

[—, no available data; ft3/s, cubic feet per second; >, greater than; exceedence frequency, percentage of time that indicated discharge was equaled or exceed

dimensionless, is the 10th- minus the 90th-percent exceedence frequency discharge divided by the median discharge; 

Analyses of data in this report: S, instantaneous or mean daily discharge used to estimate loads at this station or a nearby station; (S), instantaneous and(or) m

only prior to 1972 (prior to period of record of interest for this report); C, concentration data plotted in boxplots; (C), concentration data were combined witcollected from other locations in the same reservoir and were plotted in one boxplot per reservoir; L, annual loads reported for years with variances in load e

T, 1980–90 trends;

Surface-water station number and name sources: A, Alabama Department of Environmental Management; D, DeKalb County, Ga., monitoring network; F, 

Environmental Regulation; G, Georgia Environmental Protection Division trend-monitoring network; U, U.S. Geological Survey; UN, U.S. Geological Surv

Accounting Network]

Location 

number1/

(figure 16)

Analyse

s of data 

in this 

report

Surface-water station

River mile 

upstream of 

the mouth of 

the 

Apalachicola 

River2/

Drainage 

area

(in 

square 

miles)

Period of record Mean annual3/ 7-day, 

10-year 

low 

flow4/

(ft3/s)

Stream

exceed

Number Name (Reservoir name, if applicable) Streamflow Nutrient measurements Flow (ft3/s) Runoff (in/yr) 90 

Upper Chattahoochee (03130001)

1 S,C,L,T 02331600U

12030001G

Chattahoochee River near Cornelia, Ga.UChattahoochee River - FAS 1759 downstream from Soque RiverG

509.2 315 1957–90 1968–90 821 35.40 196 324 

2 (C),T 12038001G Chattahoochee River - Georgia Highway 

369, Browns BridgeG (Lake Sidney 

Lanier)

467.7 — — 1977–90 — — — — 

3a S 02334430U Chattahoochee River at Buford Dam near 

Buford, Ga.U

455.9 5/1,040 6/1942–55,

 1956–90

1976 6/2,173

 1,982

6/28.39

25.89

—

 7/

6/850

526

3 C,L,T 12050001G Chattahoochee River - Gwinnett County 

Water IntakeG

445.9 1,101 — 1974–90 — — — — 

4a S 02335000U Chattahoochee River near Norcross, Ga.U 438.5 5/1,170 6/1902–46,

 1956–90

1976 6/2,265

2,259

6/.26.31

26.24

—

 7/

6/860

733

4 C,L,T 12055001G Chattahoochee River - DeKalb County 

Water IntakeG

433.2 1,201 — 1974–90 — — — — 

5a S 02335700U Big Creek near Alpharetta, Ga.U 425.1

(9.3)

5/72 1960–90 1974–76 112 21.14 5.9 26 

5 C,L,T 12060001G Big Creek - Roswell Water IntakeG 425.1

(2)

103 — 1975–90 — — 8.4 — 

6 C,L,T 12070001G Chattahoochee River - Cobb County 

Water IntakeG

418.3 1,373 — 1974–90 — — — — 
43

6a, 7a S 02336000U Chattahoochee River at Atlanta, Ga.U 410.7 5/1,450 6/1928–31,

6/1936–55,

 1956–90

1974–89

6/2,567

2,524

6/24.05

23.65

—

7/

6/

1,

7 C,L,T 12080001G Chattahoochee River - Atlanta Water 

IntakeG

408.3 1,587 — 1972–90 — — — — 

8 T 12081001G North Fork Peachtree Creek - Pleasantdale Road near DoravilleD 408.3 (—) — — 1975–90 — — — — 9 T 12083001G Arrow Creek - Plaster Road near Peachtree-DeKalb AirportD 408.3 (—) — — 1975–90 — — — — 

10 T 12085001G North Fork Peachtree Creek - U.S. Highway 23D 408.3 (—) — — 1975–90 — — — — 11 T 12087001G South Fork Peachtree Creek - Johnson 

Road in AtlantaD

408.3

(—)

28.7 — 1975–90 — — 1.1 — 

12 S,C,L,T 02336300U

12090001G

Peachtree Creek at Atlanta, Ga.UPeachtree Creek - Northside Drive in 

AtlantaG

408.3

(4)

86.8 1958–90 1969–72

1975–90

137 21.37 9.5 

13 T 12090201G Nancy Creek - bridge 0.2 miles downstream from Chamblee-Dunwoody 

Road D

408.3

(—)

9.42 — 1975–90 — — — — 

14 T 12090401G Nancy Creek - at Johnsons Ferry Road 

near ChambleeD

408.3

(—)

17.8 — 1975–90 — — — — 

Table 10. Streamflow and basin characteristics for surface-water sites where data were used in nutrient analyses, by subbasin, Apalachicol

basin, 1990—Continued

[—, no available data; ft3/s, cubic feet per second; >, greater than; exceedence frequency, percentage of time that indicated discharge was equaled or exc

dimensionless, is the 10th- minus the 90th-percent exceedence frequency discharge divided by the median discharge; 

Analyses of data in this report: S, instantaneous or mean daily discharge used to estimate loads at this station or a nearby station; (S), instantaneous and(o

only prior to 1972 (prior to period of record of interest for this report); C, concentration data plotted in boxplots; (C), concentration data were combined collected from other locations in the same reservoir and were plotted in one boxplot per reservoir; L, annual loads reported for years with variances in loa

T, 1980–90 trends;Surface-water station number and name sources: A, Alabama Department of Environmental Management; D, DeKalb County, Ga., monitoring networkEnvironmental Regulation; G, Georgia Environmental Protection Division trend-monitoring network; U, U.S. Geological Survey; UN, U.S. Geological S

Accounting Network]

Location 

number1/

(figure 16)

Analyse

s of data 

in this 

report

Surface-water station

River mile 

upstream of 

the mouth of 

the 

Apalachicola 

River2/

Drainage 

area

(in 

square 

miles)

Period of record Mean annual3/ 7-day, 

10-year 

low 

flow4/

(ft3/s)

Stre

exc

Number Name (Reservoir name, if applicable) Streamflow Nutrient measurements Flow (ft3/s) Runoff (in/yr) 90 
44

Middle Chattahoochee—Lake Harding (03130002)

15a S 02336490U Chattahoochee River at State Highway 

280, near Atlanta, Ga.U

406.5 1,591 1981–90 1976–77 2,544 21.60 — 1,130 

15 C, L, T 02336502U

12105001G

Chattahoochee River at I-285, at Atlanta, 

Ga.U

Chattahoochee River - I-285 upstream 

from Proctor CreekG

405.5 1,592 — 1975–90 — — — — 

16 S, C, L, 

T

02337000U12120001G

Sweetwater Creek near Austell, Ga.USweetwater Creek - Interstate Highway 

20G

396.3

(5.5)

246 1904-05, 

1913,1937-90

1968–90 335 18.49 15 61 

17 S, C, L, 

T

02337170U12140001G

Chattahoochee River near Fairburn, Ga.UChattahoochee River-Georgia Highway 

92G

389.6 2,056 1965–90 1968–72,

1974–90

3,565 23.51 — 1,520 

18 S, C 02337500U Snake Creek near Whitesburg, Ga.U 369.5

(7)

35.5 1954–90 1968–79,

1990

56.0 21.45 9.2 17 

19 S, C, L, 

T

02338000U12150001G

Chattahoochee River near Whitesburg, 

Ga.U

Chattahoochee River-Georgia Highway 

16G

367.6 5/2,430 6/1938–54,

1965–90

1968–72,1975–90

6/3,7404,082

6/20.91

22.83

—

7/

6/1,200

1,750

20 (C), T 02338500U

12170001G

Chattahoochee River at Franklin, Ga.UChattahoochee River - U.S. Highway 27G

(inflow to West Point Lake)

343.2 5/2,680 — 1975–90 — — — — 

Table 10. Streamflow and basin characteristics for surface-water sites where data were used in nutrient analyses, by subbasin, Apalachicola – C

basin, 1990—Continued

[—, no available data; ft3/s, cubic feet per second; >, greater than; exceedence frequency, percentage of time that indicated discharge was equaled or exceed

dimensionless, is the 10th- minus the 90th-percent exceedence frequency discharge divided by the median discharge; 

Analyses of data in this report: S, instantaneous or mean daily discharge used to estimate loads at this station or a nearby station; (S), instantaneous and(or) m

only prior to 1972 (prior to period of record of interest for this report); C, concentration data plotted in boxplots; (C), concentration data were combined witcollected from other locations in the same reservoir and were plotted in one boxplot per reservoir; L, annual loads reported for years with variances in load e

T, 1980–90 trends;Surface-water station number and name sources: A, Alabama Department of Environmental Management; D, DeKalb County, Ga., monitoring network; F, 

Environmental Regulation; G, Georgia Environmental Protection Division trend-monitoring network; U, U.S. Geological Survey; UN, U.S. Geological Surv

Accounting Network]

Location 

number1/

(figure 16)

Analyse

s of data 

in this 

report

Surface-water station

River mile 

upstream of 

the mouth of 

the 

Apalachicola 

River2/

Drainage 

area

(in 

square 

miles)

Period of record Mean annual3/ 7-day, 

10-year 

low 

flow4/

(ft3/s)

Stream

exceed

Number Name (Reservoir name, if applicable) Streamflow Nutrient measurements Flow (ft3/s) Runoff (in/yr) 90 
45

21 (C),T 12180001G Chattahoochee River - LaGrange Water 

IntakeG (West Point Lake)

323.2 — — 1973–90 — — — — 

22 S,C,L,T 02339500U

12200001G

Chattahoochee River at West Point, Ga.UChattahoochee River - 1.0 mile upstream 

from U.S. Highway 29G

306.7 5/3,550 6/1896–55,

1955–90

1968–90 6/5,625

5,469

6/21.53

20.93

—

7/

6/1,660

1,050

23 C,T 02339720U

12190001G Long Cane Creek near West Point, Ga.U Long Cane Creek - FAS 1765 North of 

West PointG

302.7

(5.6)

5/74.8 — 1974–90 — — 8.5 — 

24 (C),T 12210001G Chattahoochee River - Upstream from 

Bartletts Ferry DamG (Lake Harding)

>285 — — 1972–90 — — — — 

Middle Chattahoochee—Walter F. George Reservoir (03130003)

25 C,L,T 12212001G Chattahoochee River - Columbus Water 

IntakeG

5/271 — — 1972–90 — — — — 

25a S 02341500U Chattahoochee River at Columbus, Ga.U 267.7 5/4,670 1929–90 1972 6,742 19.62 7/ 1,830 

26 C,T 12216001G Chattahoochee River - Downstream from 

Columbus WTFG (affected by 

backwater from Walter F. George Reservoir)

5/262 — — 1974–90 — — — — 

27 C, T 12218001G Chattahoochee River - Downstream 

Oswichee CreekG (affected by 

backwater from Walter F. George Reservoir)

5/248 — — 1974–90 — — — — 

Table 10. Streamflow and basin characteristics for surface-water sites where data were used in nutrient analyses, by subbasin, Apalachicola – C

basin, 1990—Continued

[—, no available data; ft3/s, cubic feet per second; >, greater than; exceedence frequency, percentage of time that indicated discharge was equaled or exceed

dimensionless, is the 10th- minus the 90th-percent exceedence frequency discharge divided by the median discharge; 

Analyses of data in this report: S, instantaneous or mean daily discharge used to estimate loads at this station or a nearby station; (S), instantaneous and(or) m

only prior to 1972 (prior to period of record of interest for this report); C, concentration data plotted in boxplots; (C), concentration data were combined witcollected from other locations in the same reservoir and were plotted in one boxplot per reservoir; L, annual loads reported for years with variances in load e

T, 1980–90 trends;Surface-water station number and name sources: A, Alabama Department of Environmental Management; D, DeKalb County, Ga., monitoring network; F, 

Environmental Regulation; G, Georgia Environmental Protection Division trend-monitoring network; U, U.S. Geological Survey; UN, U.S. Geological Surv

Accounting Network]

Location 

number1/

(figure 16)

Analyse

s of data 

in this 

report

Surface-water station

River mile 

upstream of 

the mouth of 

the 

Apalachicola 

River2/

Drainage 

area

(in 

square 

miles)

Period of record Mean annual3/ 7-day, 

10-year 

low 

flow4/

(ft3/s)

Stream

exceed

Number Name (Reservoir name, if applicable) Streamflow Nutrient measurements Flow (ft3/s) Runoff (in/yr) 90 
46

28 C, T 12219001G Chattahoochee River - Seaboard Coast 

Line Railway, OmahaG (affected by 

backwater from Walter F. George Reservoir)

227.9 — — 1972-90 — — — — 

Lower Chattahoochee (03130004)

29 (S), C 02343500G

CHA1A

Chattahoochee River at Columbia, Ala.GChattahoochee River at Highway 52 

bridge at the Georgia-Alabama state lineA

156.7 — 1928–60 1975-83 — — — — 

30 S, C, L 02343801UN Chattahoochee River near Columbia, 

Ala.UN

154.3 5/8,210 1975–90 1982–90 10,630 17.59 — 1,400 

31 (C), T 02344040U

12230001G

Chattahoochee River near Steam Mill, 

Ga.U

Chattahoochee River - Georgia Highway 

91G (inflow to Lake Seminole, Chattahoochee Arm)

131.5 — — 1974–90 — — — — 

Upper Flint (03130005)

32 C,L,T 02344180U

11011001G

Flint River near Jonesboro, Ga.UFlint River - Georgia Highway 138G

445.9 39.1 — 1975–90 — — — — 

33 C,L,T 02344190U

11013001G Flint River near Fayetteville, Ga.U Flint River - Georgia Highway 54G 441.5 49 — 1975–90 — — — — 

Table 10. Streamflow and basin characteristics for surface-water sites where data were used in nutrient analyses, by subbasin, Apalachicola – C

basin, 1990—Continued

[—, no available data; ft3/s, cubic feet per second; >, greater than; exceedence frequency, percentage of time that indicated discharge was equaled or exceed

dimensionless, is the 10th- minus the 90th-percent exceedence frequency discharge divided by the median discharge; 

Analyses of data in this report: S, instantaneous or mean daily discharge used to estimate loads at this station or a nearby station; (S), instantaneous and(or) m

only prior to 1972 (prior to period of record of interest for this report); C, concentration data plotted in boxplots; (C), concentration data were combined witcollected from other locations in the same reservoir and were plotted in one boxplot per reservoir; L, annual loads reported for years with variances in load e

T, 1980–90 trends;Surface-water station number and name sources: A, Alabama Department of Environmental Management; D, DeKalb County, Ga., monitoring network; F, 

Environmental Regulation; G, Georgia Environmental Protection Division trend-monitoring network; U, U.S. Geological Survey; UN, U.S. Geological Surv

Accounting Network]

Location 

number1/

(figure 16)

Analyse

s of data 

in this 

report

Surface-water station

River mile 

upstream of 

the mouth of 

the 

Apalachicola 

River2/

Drainage 

area

(in 

square 

miles)

Period of record Mean annual3/ 7-day, 

10-year 

low 

flow4/

(ft3/s)

Stream

exceed

Number Name (Reservoir name, if applicable) Streamflow Nutrient measurements Flow (ft3/s) Runoff (in/yr) 90 
47

 32a, 

33a, 34a

S 02344350U Flint River near Lovejoy, Ga.U 433.5 130 1985–90 1988 167 17.42 — 29 

34 C,L,T 02344380U

11015001G

Flint River near Inman, Ga.UFlint River - Ackert Road near InmanG

430.1 158 — 1975–90 — — — — 

35 C,L,T 02344400U

11018001G

Flint River above Griffin, Ga.UFlint River - Georgia Highway 92G

421.0 194 — 1975–90 — — — — 

35a S 02344500U Flint River near Griffin, Ga.U 412.2 272 1937–90 1972 344 17.21 15 60 

36 S,C,L 02347500U

11050001G

Flint River near Culloden, Ga.UFlint River - U.S. Highway 19 near 

CullodenG

346.2 5/1,850 1911–23,

1928–31,1937–90

1968–79,1990

2,325 17.08 180 450 

Middle Flint (03130006)

37 S,C,L,T 02349500U

11060001G

Flint River at Montezuma, Ga.UFlint River - Georgia Highways 26 and 

49G

288.4 5/2,900 1904–12,

1930–90

1968–74,1976–90

3,534 16.56 680 1,070 

38 (C), T 02350001U

11061301G

Flint River near Vienna, Ga.UFlint River - Georgia Highway 27 near 

ViennaG (inflow to Lake Blackshear)

261.9 3,390 — 1979–90 — — — — 

Kinchafoonee-Muckalee (03130007)

39 C 02350600U

11065001G

Kinchafoonee Creek at Preston, Ga.UKinchafoonee Creek- Georgia Highway 

41G

211.6

(—)

197 — 1969–70,

1971–90

— — — — 

Table 10. Streamflow and basin characteristics for surface-water sites where data were used in nutrient analyses, by subbasin, Apalachicola – C

basin, 1990—Continued

[—, no available data; ft3/s, cubic feet per second; >, greater than; exceedence frequency, percentage of time that indicated discharge was equaled or exceed

dimensionless, is the 10th- minus the 90th-percent exceedence frequency discharge divided by the median discharge; 

Analyses of data in this report: S, instantaneous or mean daily discharge used to estimate loads at this station or a nearby station; (S), instantaneous and(or) m

only prior to 1972 (prior to period of record of interest for this report); C, concentration data plotted in boxplots; (C), concentration data were combined witcollected from other locations in the same reservoir and were plotted in one boxplot per reservoir; L, annual loads reported for years with variances in load e

T, 1980–90 trends;Surface-water station number and name sources: A, Alabama Department of Environmental Management; D, DeKalb County, Ga., monitoring network; F, 

Environmental Regulation; G, Georgia Environmental Protection Division trend-monitoring network; U, U.S. Geological Survey; UN, U.S. Geological Surv

Accounting Network]

Location 

number1/

(figure 16)

Analyse

s of data 

in this 

report

Surface-water station

River mile 

upstream of 

the mouth of 

the 

Apalachicola 

River2/

Drainage 

area

(in 

square 

miles)

Period of record Mean annual3/ 7-day, 

10-year 

low 

flow4/

(ft3/s)

Stream

exceed

Number Name (Reservoir name, if applicable) Streamflow Nutrient measurements Flow (ft3/s) Runoff (in/yr) 90 
48

Lower Flint (03130008)

40, 41a S,C,L,T 02352500U

11090001G Flint River at Albany, Ga.U Flint River - Georgia Northern Railway, 

AlbanyG

211.2 5/5,310 1901–21,

1929–90

1968–90 6,158 15.76 7/ 1,780 

41 C,L,T 02352790U

11100001G Flint River near Putney, Ga.U Flint River - Plant Mitchell IntakeG 198.6 5/5,340 — 1974–90 — — — — 

42 S,C,L 02353000UN Flint River at Newton, Ga.UN 177.3 5/5,740 1938–50,

1956–90

1968–79,1983–90

6,538 15.48 — 2,190 

43 (C),T 02356015U

11110001G Flint River below Bainbridge, Ga.U Flint River - 0.8 miles downstream from 

State DocksG (inflow to Lake Seminole, Flint Arm)

134.3 5/7,570 — 1974–90 — — — — 

Ichawaynochaway (03130009)

44 S,C 02353500U

11106001G

Ichawaynochaway Creek at Milford, 

Ga.U

Ichawaynochaway Creek - Georgia Highway 216 near MilfordG

160.6

(—)

5/640 1905–07,

1939–90

1970–90 773 16.94 — 242 

Table 10. Streamflow and basin characteristics for surface-water sites where data were used in nutrient analyses, by subbasin, Apalachicola – C

basin, 1990—Continued

[—, no available data; ft3/s, cubic feet per second; >, greater than; exceedence frequency, percentage of time that indicated discharge was equaled or exceed

dimensionless, is the 10th- minus the 90th-percent exceedence frequency discharge divided by the median discharge; 

Analyses of data in this report: S, instantaneous or mean daily discharge used to estimate loads at this station or a nearby station; (S), instantaneous and(or) m

only prior to 1972 (prior to period of record of interest for this report); C, concentration data plotted in boxplots; (C), concentration data were combined witcollected from other locations in the same reservoir and were plotted in one boxplot per reservoir; L, annual loads reported for years with variances in load e

T, 1980–90 trends;Surface-water station number and name sources: A, Alabama Department of Environmental Management; D, DeKalb County, Ga., monitoring network; F, 

Environmental Regulation; G, Georgia Environmental Protection Division trend-monitoring network; U, U.S. Geological Survey; UN, U.S. Geological Surv

Accounting Network]

Location 

number1/

(figure 16)

Analyse

s of data 

in this 

report

Surface-water station

River mile 

upstream of 

the mouth of 

the 

Apalachicola 

River2/

Drainage 

area

(in 

square 

miles)

Period of record Mean annual3/ 7-day, 

10-year 

low 

flow4/

(ft3/s)

Stream

exceed

Number Name (Reservoir name, if applicable) Streamflow Nutrient measurements Flow (ft3/s) Runoff (in/yr) 90 
49

Apalachicola (03130011)

45 S,C,L,T 02358000UN Apalachicola River at Chattahoochee, 

Fla.UN

106 5/17,200 1928–90 1962–72,

1974–90

22,080 17.44 5,250 8,920 

46a S 02359170U Apalachicola River near Sumatra, Fla.U 20.6 5/19,200 1977–90 1979–80 25,960 18.37 6,890 9,840 

46 C,L,T 31010022F Apalachicola River, Buoy 40, mile 11AF 11.0 — — 1974–90 — — — — 

Chipola (03130012)

47 S,C,L,T 02359000UN Chipola River near Altha, Fla.UN 28.2

 (54)

781 1912–13, 

1921–27, 1929–31, 1943–90

1962–72, 

1974–90

1,492 25.95 425 619 

1/ Surface water-quality sampling sites are numbered consecutively; surface-water gaging stations that are paired with water-quality sampling sites either upstream or down

gage location are designated with a letter “a.”

2/ For tributary streams, the river mile of the confluence between the tributary and the Chattahoochee, Flint, or Apalachicola Rivers is listed first and the distance upstream 

confluence is listed in parentheses.

3/ Statistics calculated for the period of record through 1992 water year.4/ Data sources for 7-day, 10-year low flow: Upper Chattahoochee River (Carter and others, 1989); Upper Flint River (Carter and others, 1986, and Carter and Putnam, 1978

(Marvin Franklin, U.S. Geological Survey, Florida District, oral commun., 1994).

5/ Approximate.6/ Prior to regulation.7/ Flow is regulated by upstream reservoir(s). Low-flow estimates prior to 1974 are available in Carter and Putnam (1978).

Table 10. Streamflow and basin characteristics for surface-water sites where data were used in nutrient analyses, by subbasin, Apalachicola 

basin, 1990—Continued

[—, no available data; ft3/s, cubic feet per second; >, greater than; exceedence frequency, percentage of time that indicated discharge was equaled or excee

dimensionless, is the 10th- minus the 90th-percent exceedence frequency discharge divided by the median discharge; 

Analyses of data in this report: S, instantaneous or mean daily discharge used to estimate loads at this station or a nearby station; (S), instantaneous and(or) 

only prior to 1972 (prior to period of record of interest for this report); C, concentration data plotted in boxplots; (C), concentration data were combined wcollected from other locations in the same reservoir and were plotted in one boxplot per reservoir; L, annual loads reported for years with variances in load 

T, 1980–90 trends;Surface-water station number and name sources: A, Alabama Department of Environmental Management; D, DeKalb County, Ga., monitoring network; F

Environmental Regulation; G, Georgia Environmental Protection Division trend-monitoring network; U, U.S. Geological Survey; UN, U.S. Geological Su

Accounting Network]

Location 

number1/

(figure 16)

Analyse

s of data 

in this 

report

Surface-water station

River mile 

upstream of 

the mouth of 

the 

Apalachicola 

River2/

Drainage 

area

(in 

square 

miles)

Period of record Mean annual3/ 7-day, 

10-year 

low 

flow4/

(ft3/s)

Strea

exce

Number Name (Reservoir name, if applicable) Streamflow Nutrient measurements Flow (ft3/s) Runoff (in/yr) 90 
30

31

33

34

84

85

32

o

o

o

o

o

o

o

Apalachicola Bay

Ch pi ola River

Apalachicola River

Chattahoochee River

Fl ni t River

Chattahoochee River

Lake

Seminole Seminole

Walter F Walter F

George

Reservoir Reservoir

Lake

Harding Harding

Lake

Harding

Lake

Sidney

Lanier

Lake

Sidney

Lanier

West

Point

Lake

West

Point

Lake

Lake

Blackshear

Walter F

George

Reservoir

Lake

Seminole

0 20 40 60 80 MILES

0 20 40 60 80 KILOMETERS

3

19 33

34

20

21

18

17

6

15

13

2

23

24

26

30

43

46

45

31

44

25

39

35

4

32

22

29

47

27

28

7

16

8

9

11

5

36

37

38

41

42

1

32a,33a,34a

15a

3a

46a

35a

4a

6a,7a

5a

12

25a

40,41a

14

10

36

DATA AVAILABILITY AND LOCATION NUMBERS 

 FOR TABLE 10

Nutrient concentrations and

 continuous streamflow data

Nutrient concentrations only

Continuous streamflow only

EXPLANATION

4a

3

Urban areas mentioned in analyses

 of nutrients in surface water

Figure 16. Locations of surface-water sites where data were used in nutrient analyses, ApalachicolaChattahoochee-Flint River basin, 1990.

Base from U.S. Geological Survey digital files

Atlanta

Albany

Gainesville

LaGrange aGrange

Columbus and

Phenix City

50
51

conditions; location, duration, and intensity of 

precipitation; modification or regulation of discharge 

by reservoirs; mixture of point and nonpoint sources; 

land use and land cover in the upstream watershed; 

topography; and streamflow conditions (rising limb, 

peak, falling limb, baseflow) when samples were 

collected. The result of these and other factors is 

often an unclear relation between concentration and 

stream discharge.

It is difficult to separate the effects of point and 

nonpoint sources of nutrients on a regional scale 

based on historic data collected for various purposes. 

However, as part of the Upper Chattahoochee River 

Quality Assessment, Stamer and others (1979) 

sampled a 4-day storm period in 1976 and 2-day lowflow period in 1977 to separate point and nonpoint 

sources for nutrients and several other constituents. 

During the storm period, in the Atlanta-to-Fairburn 

reach, urban nonpoint-source inputs to Peachtree 

Creek (location 12) were about an order-of-magnitude 

greater than rural nonpoint-source inputs to Big Creek 

(location 5a) or forested nonpoint-source inputs to 

Snake Creek (location 18) (Stamer and others, 1979, 

p. 31). During the low-flow period, five municipal 

point sources contributed 97 percent of ammonia, 78 

percent of total nitrogen, and 90 percent of totalphosphorus loads at Chattahoochee River at Franklin 

(location 20) (Stamer and others, 1979, p. 62). 

Ideally, water-quality samples are collected at 

times that represent the range of flow conditions for 

each sampling site. It is particularly important to have 

water-quality samples that are representative of highflow conditions because, for many constituents, much 

of the transport (load) occurs during high-flow 

conditions, and there is generally more variance in 

concentrations during high-flow conditions than 

during low-flow conditions. A good sampling design 

includes collecting more samples during conditions 

likely to have the most variance in concentrations of 

the constituents of interest. Distributions of nutrient 

samples by decile of flow for nine surface-water 

sampling sites indicate that most flow conditions were 

well represented by sampling from 1972–90 (fig. 17). 

Minor under-sampling of low flows at the Gwinnett 

County Water Intake (location 3) and the Columbus 

Water Intake (location 25) on the Chattahoochee 

River occurred because these sites are downstream of 

reservoirs that are operated for peaking hydropower 

generation. Lowest power demand and, therefore, 

lowest releases are generally on weekends; whereas, 

routine monitoring samples are generally collected 

Monday through Friday. The distribution of fewer 

samples collected in the highest decile of flow at 

Peachtree Creek at Atlanta (location 12) is fairly 

typical of tributary streams because high-flow events 

are generally shorter in duration and, therefore, more 

difficult to sample in small watersheds.

Using concentration data for 1972–90 water 

years, most surface-water sampling sites in the ACF 

River basin have weak, indeterminate, or no relations 

between concentrations of dissolved ammonia, 

dissolved nitrate, and total phosphorus and the 

logarithm of discharge. Nutrient concentration and 

logarithm of discharge are plotted along with a 

LOWESS line (LOcally WEighted Scatterplot 

Smoothing) for two mainstem and four tributary sites 

(figs. 18–20). LOWESS lines emphasize the shape of 

the relation between concentration and discharge and 

are computed by fitting 2n weighted least-square 

equations, which is a robust method to compute a 

moving average (Helsel and Hirsch, 1992, p. 288–

291). Kendall’s tau is a rank correlation coefficient 

that indicates monotonically increasing or decreasing 

relations between two variables. Statistically significant correlations (at the 95-percent confidence level) 

between ranked concentrations of dissolved ammonia, 

dissolved nitrate, and total phosphorus and ranked 

discharge are listed in figures 18–20. The higher the 

absolute value of tau, the stronger the positive or 

negative correlation.

Decreasing relations among dissolved-ammonia, 

dissolved-nitrate, and total-phosphorus concentrations 

and discharge at Chattahoochee River near Fairburn 

(downstream of Atlanta) are indicative that point 

sources account for much of the load. Relatively 

small decreases in dissolved-nitrate concentrations as 

stream discharge increases at Flint River near Putney 

(downstream from Albany; location 41) could be 

from dilution of baseflow or dilution of point-source 

loads. At Chipola River near Altha (location 47), 

decreases in dissolved-nitrate concentration as stream 

discharge increases may be the result of diluting 

nitrate concentrations in baseflow, which is predominantly from ground water. The Chipola River 

drains largely agricultural areas in karst environments 

that have relatively high transmissivities in the 

aquifer, which increases the likelihood of elevated 

nitrate concentrations in ground water. Strong 

negative relations between dissolved-ammonia (fig. 

18) and total-phosphorus (fig. 20) concentrations and 

discharge in Long Cane Creek are indications that the 

primary source for these nutrient constituent groups 

during 1972–90 was point-source loads. For this time 

period, the city of LaGrange discharged effluent into 

Long Cane Creek. As of September 1993, the 

discharge location was moved to the Chattahoochee
Figure 17. Distribution of nutrient samples within decile-flow classes for nine stream-sampling sites, Apalachicola-Chattaho

1972–90 water years.

DECILES OF FLOW

Chattahoochee River,Gwinnett County Water Intake, Ga.(location 3, Figure 16) 

Chattahoochee River,Columbus Water Intake, Ga.(location 25)

Flint River above Griffin, Ga.(location 35)

Flint River at Montezuma, Ga.(location 37)

5040302010

0

5040302010

0

5040302010

0

NUMBER OF NUTRIENT WATER-QUALITY SAMPLES

Chattahoochee River near Fairburn, Ga.(location 17)

Flint River near Putney, Ga.(location 41)

Chipola River near Altha, Fla.(location 47)

Apalachicola River,Bouy 40, mile 11A, Fla.(location 46)

Peachtree Creek at Atlanta(location 12)

0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 

0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 

0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 

0 10 20 30 40 50 60 70 80 90 100

52
100

10

1

0.100.01

100

10

1

0.100.01

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

DISSOLVED-AMMONIA CONCENTRATION AS N, IN MILLIGRAMS PER LITER

INSTANTANEOUS DISCHARGE, IN CUBIC FEET PER SECOND

EXPLANATION

Figure 18. Relation between dissolved-ammonia concentration and discharge for two mainstem and four tributary sampling 

Chattahoochee-Flint River basin, 1972–90 water years.

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

Chattahoochee River near Fairburn, Ga.(location 17, Figure 16)Kendall's tau: –0.57

Flint River near Putney, Ga.(location 41)Kendall's tau: –0.27

Peachtree Creek at Atlanta, Ga.(location 12)Kendall's tau: not significant

Sweetwater Creek near Austell, Ga.(location 16)Kendall's tau: not significant

Chipola River near Alth(location 47)Kendall's tau: not signifLong Cane Creek near (location 23)Kendall's tau: –0.38

LOWESS LINE CENSORING LIMIT

53
Kendall's tau: –0.38

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

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

INSTANTANEOUS DISCHARGE, IN CUBIC FEET PER SECOND

Chattahoochee River near Fairburn, Ga.(location 17, Figure 16)Kendall's tau: –0.41

Flint River near Putney, Ga.(location 41)Kendall's tau: –0.28

Chipola River near Alth(location 47)

Peachtree Creek at Atlanta, Ga.(location 12)Kendall's tau: 0.23

Sweetwater Creek near Austell, Ga.(location 16)Kendall's tau: not significant

Long Cane Creek near (location 23)Kendall's tau: –0.19

100

10

1

0.100.01

100

10

1

0.100.01

DISSOLVED-NITRATE CONCENTRATION AS N, IN MILLIGRAMS PER LITER

Figure 19. Relation between dissolved-nitrate concentration and discharge for two mainstem and four tributary sampling s

Chattahoochee-Flint River basin, 1972-90 water years.

EXPLANATION

LOWESS LINE

54
100

10

1

0.100.01

100

10

1

0.100.01

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

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

INSTANTANEOUS DISCHARGE, IN CUBIC FEET PER SECOND

TOTAL-PHOSPHORUS CONCENTRATION AS P, IN MILLIGRAMS PER LITER Kendall's tau: 0.29 Chattahoochee River near Fairburn, Ga. (location 17, Figure 16) Kendall's tau: –0.48 Flint River near Putney, Ga. (location 41) Kendall's tau: –0.25 Chipola River near Alth

(location 47) Peachtree Creek at Atlanta, Ga. (location 12) Kendall's tau: 0.25 Sweetwater Creek near Austell, Ga. (location 16) Kendall's tau: 0.29 Long Cane Creek near (location 23) Kendall's tau: –0.62

Figure 20. Relation between total-phosphorus concentration and discharge for two mainstem and four tributary sampling Chattahoochee-Flint River basin, 1972–90 water years.

EXPLANATION

LOWESS LINE CENSORING LIMIT

55
56

River about one mile below the confluence of Long 

Cane Creek and the Chattahoochee River (Anne 

Westmoreland, Long Cane Creek WPCP, oral 

commun., 1994). By contrast, Peachtree and 

Sweetwater Creeks have relatively weak positive 

relations between total phosphorus and discharge (fig. 

20). Transport of phosphorus is often closely related 

to transport of suspended sediment, which is usually a 

nonpoint-source dominated phenomena. In addition 

to typical urban nonpoint sources, Peachtree Creek 

has three combined sewer overflows, which are point 

sources that have significantly larger discharge during 

high-flow events.

Downstream variations in concentrations

Possible causes for increases in nutrient 

concentrations from an upstream sampling site to a 

downstream sampling site in the ACF River basin 

include: 

• point sources of nutrients, 

• land use and land cover that has a higher 

nonpoint-source yield of nutrients, 

• inflow of ground water with higher 

concentrations of a nutrient species than 

the surface water (most commonly 

nitrate), 

• suspension of sediments and nutrients 

from stream or reservoir bottoms, 

• rupture of phytoplankton cells as they are 

transported from lacustrine to riverine 

environments, 

• die off of phytoplankton in the fall and 

winter because of cooler water 

temperatures, and 

• aquatic weed or detritus input. 

The most common causes for decreases in 

nutrient concentrations as surface water flows 

downstream within the ACF River basin include 

settling of sediments and associated phosphorus, 

settling of detritus (mostly organic nitrogen), inflow 

from tributaries with lower nutrient concentrations 

(dilution), and uptake by phytoplankton in reservoirs 

(particularly in the spring and summer). In addition to 

net increases or decreases in nutrients, it is common 

for ammonia to be converted to nitrate in surface 

waters downstream of WWTF outfalls. Therefore, in 

reaches downstream of large cities, ammonia 

concentrations often decrease while nitrate 

concentrations increase.

This section focuses on differences in nutrient 

concentrations in surface water within the study area 

based on 19 years of concentration data (1972–90 

water years). Instantaneous discharge when nutrient 

samples were collected (fig. 21) and nutrient 

concentrations (figs. 22 to 29) are summarized in 

boxplots by river mile upstream of the mouth of the 

Apalachicola River. Each boxplot represents the 10th, 

25th, 50th (median), 75th, and 90th percentile 

distribution of the data. Nutrient data from different 

sampling sites and depths within individual reservoirs 

were compiled and plotted as single boxplots at the 

downstream end of each reservoir. Lake Seminole 

data are plotted either on the Chattahoochee or Flint 

River basin figures depending on the arm of the 

reservoir in which they were collected. The mouths 

of the Chattahoochee and Flint Rivers join at Lake 

Seminole to form the headwaters of the Apalachicola 

River. Data from the Apalachicola River are shown 

downstream of the Chattahoochee River data and are 

repeated downstream of the Flint River data. MannWhitney tests, a nonparametric t-test involving ranktransformed data (Inman and Conover, 1983, p. 280–

281), were used to determine if nutrient concentrations at paired upstream and downstream sites were 

statistically different. Boxplots were used to show if 

statistically different concentrations distributions 

increase or decrease in the downstream direction.

In general, the Chattahoochee, Flint, and Apalachicola Rivers are gaining rivers throughout their 

extent (fig. 21). The ACF River basin does not have 

major changes in nutrient concentrations that are primarily the result of large inflows or diversions of 

water.

Concentrations of nutrients significantly increased from upstream to downstream of the three 

major cities (Atlanta, locations 6–17; Columbus and 

Phenix City, locations 25 and 26; and Albany, 

locations 40 and 41) in the ACF River basin (table 

11). These increases were expected because of urban 

and suburban point and nonpoint sources of nutrients. 

Atlanta, Columbus and Phenix City, and Albany were 

the only metropolitan areas with municipal discharges 

larger than 10 Mgal/d in 1990 in the ACF River basin 

(fig. 6). Significant increases in concentrations of 

total nitrogen (fig. 22; Atlanta only), total-inorganic 

nitrogen (fig. 23), total-organic nitrogen (fig. 24; 

Atlanta only), dissolved ammonia (fig. 25), dissolved 

nitrate (fig. 26), and total phosphorus (fig. 28) are 

common below WWTF discharge locations; however, 

it is not known how much of the increases are the 

result of point versus nonpoint sources. There were
Figure 21. Instantaneous discharge when nutrient samples were collected in (A) Chattahoochee and 

Apalachicola, and (B) Flint and Apalachicola River basins, 1972–90 water years. 

DISTANCE, IN RIVER MILES UPSTREAM OF MOUTH OF APALACHICOLA RIVER

550 500 450 400 350 300 250 200 150 100 50 0

550 500 450 400 350 300 250 200 150 100 50 0

INSTANTANEOUS DISCHARGE, IN CUBIC FEET PER SECOND

100,000

10,000

1,000

10

1

100,000

10,000

1,000

10

1

30 45 47 46

22

3 4 5 6 7 23 25

12

15

16

17 18

19

1

32

33

34

35

36 37 39

40

41 42 44 45 47 46

101

176

217

192

192

176

265 330

55 203

189

223

204

171

221

48

153

134

101

Apalachicola River basin Apalachicola River basin

Chattahoochee River basin

Flint River basin

A

B

Atlanta

Albany

Atlanta

Columbus

183

185

180

244

59 168

73

78

213 55

40

153

134

101

LOCATION (Figure 16) 

Number of samples

 with discharge

 measurements 

90

75

50

25

10

Percentile

Main stem 20

Tributary

57
104

72

152

37

880 72

351

41

121

114

63

136

Figure 22. Downstream variation in total-nitrogen concentrations in (A) Chattahoochee and Apalachicola, 

and (B) Flint and Apalachicola River basins, 1972–90 water years.

DISTANCE, IN RIVER MILES UPSTREAM OF MOUTH OF APALACHICOLA RIVER

550 500 450 400 350 300 250 200 150 100 50 0 

550 500 450 400 350 300 250 200 150 100 50 0 

TOTAL-NITROGEN CONCENTRATION AS N, IN MILLIGRAMS PER LITER

10

1

0.10

0.01

10

1

0.10

0.01

6 17 18 27

Walter F GeorgeReservoir

30 45 47 46

35

148

47

24

68 30

86

136

141

63

47

37 39 41 42 44 45 47 46 Apalachicola River basin Apalachicola River basin

Chattahoochee River basin

Flint River basin

A

B

Lake SidneyLanier

West PointLake

Lake SeminoleChattahoochee arm

Lake SeminoleFlint arm

Atlanta

Columbus

Atlanta

Albany

LOCATION (Figure 16) 

Number of samples 

90

75

50

25

10

Percentile

Main stem 20

Tributary

Reservoir—

 Multiple

 sampling sites

Censoring limit

Censoring limit

58
222

214

219

228

57 154

125

66

71

198 52 39

297

153

134

83

Figure 23. Downstream variation in total-inorganic-nitrogen concentrations in (A) Chattahoochee and 

Apalachicola, and (B) Flint and Apalachicola River basins, 1972–90 water years.

Censoring limit

Censoring limit

DISTANCE, IN RIVER MILES UPSTREAM OF MOUTH OF APALACHICOLA RIVER

550 500 450 400 350 300 250 200 150 100 50 0 

550 500 450 400 350 300 250 200 150 100 50 0 

TOTAL-INORGANIC-NITROGEN CONCENTRATION AS N, IN MILLIGRAMS PER LITER

10

1

0.10

0.01

10

1

0.10

0.01

Walter F GeorgeReservoir

30 45 47 46

22

3 4 5 6 7 23 25 26 27 28

12

15

16

17 18

19

1

LOCATION (Figure 16) 

32

33

34

35

36 37 39

40

41 42 44 45 47 46

94 220

155165

164

184

258 327

51

188

191

204 185

195

1,571

204

224

212

177174 193 956

42 394

153

134

83

Apalachicola River basin Apalachicola River basin

Chattahoochee River basin

Flint River basin

A

B

Lake SidneyLanier

West PointLake

Lake Harding

Lake SeminoleChattahoochee arm

Lake SeminoleFlint arm

LakeBlackshear

Atlanta

Columbus

Atlanta

Albany

Number of samples 

90

75

50

25

10

Percentile

Main stem 20

Tributary

Reservoir—

 Multiple

 sampling sites

59
104

72

151

39 980 68

344

47

114 114

55 136

Figure 24. Downstream variation in total-organic-nitrogen concentrations in (A) Chattahoochee and 

Apalachicola, and (B) Flint and Apalachicola River basins, 1972–90 water years.

DISTANCE, IN RIVER MILES UPSTREAM OF MOUTH OF APALACHICOLA RIVER

550 500 450 400 350 300 250 200 150 100 50 0

550 500 450 400 350 300 250 200 150 100 50 0

TOTAL-ORGANIC-NITROGEN CONCENTRATION AS N, IN MILLIGRAMS PER LITER

10

1

0.10

0.01

10

1

0.10

0.01

6 17 18 27

Walter F GeorgeReservoir

30 45 47 46

35

142

43

29

66

30

84136 114 55 49

37 39 41 42 44 45 47 46 Apalachicola River basin Apalachicola River basin

Chattahoochee River basin

Flint River basin

A

B

Lake SidneyLanier

West PointLake

Lake SeminoleChattahoochee arm

Lake SeminoleFlint arm

Atlanta

Columbus

Atlanta

Albany

LOCATION (Figure 16) 

Number of samples 

90

75

50

25

10

Percentile

Main stem 20

Tributary

Reservoir—

 Multiple

 sampling sites

Censoring limit

Censoring limit

60
222

214

219

228

57

154 126

71

72 202

54

39

297

153

134

84

Figure 25. Downstream variation in dissolved-ammonia concentrations in (A) Chattahoochee and 

Apalachicola, and (B) Flint and Apalachicola River basins, 1972–90 water years.

DISTANCE, IN RIVER MILES UPSTREAM OF MOUTH OF APALACHICOLA RIVER

550 500 450 400 350 300 250 200 150 100 50 0

550 500 450 400 350 300 250 200 150 100 50 0

DISSOLVED-AMMONIA CONCENTRATION AS N, IN MILLIGRAMS PER LITER

Censoring limit

Censoring limit

10

1

0.10

0.01

10

1

0.10

0.01

Walter F GeorgeReservoir

30 45 47 46

22

3 4 5 6 7 23 25 26 27 28

12

15

16

17 18

19

1

32

33

34

35

36 37 39

40

41 42 44 45 47 46

94

220

162

169

191

184 257

329

54

197

191

206

174

195

1,754

204

225 212

180

171

193

955

48 397

153

134

84

Apalachicola River basin Apalachicola River basin

Chattahoochee River basin

Flint River basin

A

B

Lake SidneyLanier

West PointLake

Lake Harding

Lake SeminoleChattahoochee arm

Lake SeminoleFlint arm

LakeBlackshear

Atlanta

Albany

Atlanta

Columbus

LOCATION (Figure 16) 

Number of samples 

90

75

50

25

10

Percentile

Main stem 20

Tributary

Reservoir—

 Multiple

 sampling sites

61
226

217

225

236

59 168 136

67

76 205

53 40

293

153

134

98

Figure 26. Downstream variation in dissolved-nitrate concentrations in (A) Chattahoochee and 

Apalachicola, and (B) Flint and Apalachicola River basins, 1972–90 water years. (U.S. Environmental

Protection Agency's maximum contaminant level for nitrate is 10 milligrams per liter.)

DISTANCE, IN RIVER MILES UPSTREAM OF MOUTH OF APALACHICOLA RIVER

550 500 450 400 350 300 250 200 150 100 50 0

550 500 450 400 350 300 250 200 150 100 50 0 

DISSOLVED-NITRATE CONCENTRATION AS N, IN MILLIGRAMS PER LITER

10

1

0.10

0.01

10

1

0.10

0.01

30

29

Walter F GeorgeReservoir

45 47 46

22

3 4 5 6 7 23 25 26 27 28

12

15

16

17 18

19

1

32

33

34

35

36 37 39

40

41 42 44 45 47 46

100

272

165

196

213

192185

258 326

52

195

184

176

1,530

192

199

222

217

178 175 197 976 105

37

413

153

134

98

Apalachicola River basin Apalachicola River basin

Chattahoochee River basin

Flint River basin

A

B

Albany

Number of samples 

90

75

50

25

10

Percentile

Main stem 20

Tributary

Reservoir—

 Multiple

 sampling sites

Lake SidneyLanier

West PointLake

Lake Harding

Lake SeminoleChattahoochee arm

Lake SeminoleFlint arm

LakeBlackshear

Atlanta

Columbus

Atlanta

LOCATION (Figure 16) 

62
38

60

62

66

44

Figure 27. Downstream variation in dissolved-organic-nitrogen concentrations in (A) Chattahoochee and 

Apalachicola, and (B) Flint and Apalachicola River basins, 1972–90 water years.

DISTANCE, IN RIVER MILES UPSTREAM OF MOUTH OF APALACHICOLA RIVER

550 500 450 400 350 300 250 200 150 100 50 0 

550 500 450 400 350 300 250 200 150 100 50 0 

DISSOLVED-ORGANIC-NITROGEN CONCENTRATION AS N, IN MILLIGRAMS PER LITER

10

1

0.10

0.01

10

1

0.10

0.01

18 45 47

21 28

66 44

39 44 45 47 Apalachicola River basin Apalachicola River basin

Chattahoochee River basin

Flint River basin

A

B

Lake SidneyLanier

West PointLake

Atlanta

Albany

Atlanta

Columbus

LOCATION (Figure 16) 

Censoring limit

Censoring limit

Number of samples 

90

75

50

25

10

Percentile

Main stem 20

Tributary

Reservoir—

 Multiple

 sampling sites

63
229

216

227

239

59

168 138

74

77 209

54

40

300

153

132

101

Figure 28. Downstream variation in total-phosphorus concentrations in (A) Chattahoochee and Apalachicola, 

and (B) Flint and Apalachicola River basins, 1972–90 water years. 

DISTANCE, IN RIVER MILES UPSTREAM OF MOUTH OF APALACHICOLA RIVER

550 500 450 400 350 300 250 200 150 100 50 0

550 500 450 400 350 300 250 200 150 100 50 0 

TOTAL-PHOSPHORUS CONCENTRATION AS P, IN MILLIGRAMS PER LITER

10

1

0.10

0.01

10

1

0.10

0.01

30

29

Walter F George

Reservoir

45 47 46

22

3 4 5 6 7 23 25 26 27 28

12

15

16

17 18

19

1

32

33

34

35

36 37 39

40

41 42 44 45 47 46

100

249

173

216

217

192

185

260

328

45

203 189

186

1,705

199

203

237

220

175

174

198

991

93

48

422

153

132

101

Apalachicola River basin Apalachicola River basin

Chattahoochee River basin

Flint River basin

A

B

Albany

Lake Sidney

Lanier

West Point

Lake

Lake Harding

Lake Seminole

Chattahoochee arm

Lake SeminoleFlint arm

Lake

Blackshear

Atlanta

Columbus

Atlanta

LOCATION (Figure 16) 

Number of samples 

90

75

50

25

10

Percentile

Main stem 20

Tributary

Reservoir—

 Multiple

 sampling sites

Censoring limit

Censoring limit

64
284

15

17

48

981

300 48

84 105 85

Figure 29. Downstream variation in dissolved-orthophosphate concentrations in (A) Chattahoochee and 

Apalachicola, and (B) Flint and Apalachicola River basins, 1972–90 water years.

DISTANCE, IN RIVER MILES UPSTREAM OF MOUTH OF APALACHICOLA RIVER

550 500 450 400 350 300 250 200 150 100 50 0

550 500 450 400 350 300 250 200 150 100 50 0 

DISSOLVED-ORTHOPHOSPHATE CONCENTRATION AS P, IN MILLIGRAMS PER LITER

10

1

0.10

0.01

10

1

0.10

0.01

17 18

Walter F GeorgeReservoir

30 45 47

19

29 30

91

105 85

49

39 42 44 45 47 Apalachicola River basin Apalachicola River basin

Chattahoochee River basin

Flint River basin

A

B

Lake SidneyLanier

West PointLake

Lake SeminoleChattahoochee arm

Lake SeminoleFlint arm

Atlanta

Albany

Atlanta

Columbus

LOCATION (Figure 16) 

Number of samples 

90

75

50

25

10

Percentile

Main stem 20

Tributary

Reservoir—

 Multiple

 sampling sites

Censoring limit

Censoring limit

65
66

Table 11. Comparison1/ of nutrient concentrations at sampling sites upstream and downstream of major cities, 

Apalachicola–Chattahoochee–Flint River basin, 1972–90 water years

[–, no available data; ↑ , concentration significantly increased from upstream to downstream of city]

Location 

number 

(figure 

16)

Comparison sites

in downstream order

Nutrient constituents

Total 

nitrogen 

(figure 22)

Totalinorganic 

nitrogen 

(figure 23)

Totalorganic 

nitrogen 

(figure 24)

Dissolved 

ammonia 

(figure 25)

Dissolved 

nitrate 

figure 26)

Total 

phosphorus 

(figure 28)

Atlanta

6 Chattahoochee River - Cobb County Water 

Intake ↑ ↑ ↑ ↑ ↑ ↑

17 Chattahoochee River near Fairburn, Ga.

Columbus and Phenix City

25 Chattahoochee River - Columbus Water 

Intake – ↑ – ↑ ↑ ↑

26 Chattahoochee River - Downstream from 

Columbus WTF

Albany

40 Flint River at Albany, Ga. – ↑ – ↑ ↑ ↑

41 Flint River near Putney, Ga.

1/ An increase between two sampling sites was based on results from Mann-Whitney rank-sum tests (Inman and Conover, 

1983). The confidence level for significant differences was the 95th percentile.

insufficient data to determine changes in dissolvedorganic-nitrogen and dissolved-orthophosphate concentrations for all three metropolitan areas, and for 

total-nitrogen and total-organic-nitrogen concentrations for Columbus and Phenix City and Albany.

Concentrations upstream and downstream of 

point sources could not be compared for the 

headwaters of the Flint River (downstream of Atlanta, 

locations 32 to 35) and Long Cane Creek 

(downstream of LaGrange, location 23) because there 

were no nutrient-sampling sites upstream of the pointsource discharge. However, total-inorganic-nitrogen, 

dissolved-ammonia, dissolved-nitrate, and totalphosphorus (figs. 23, 25, 26, and 28) concentrations 

during 1972–90 water years at these sites were 

elevated to levels similar to those downstream of 

major point sources in Atlanta, Columbus and Phenix 

City, and Albany. For the headwaters of the Flint 

River, Long Cane Creek, and for Flat Creek 

(Gainesville WPCP No 1) and South Fork Little Mud 

Creek (Cornelia WPCP) in the Upper Chattahoochee 

subbasin (fig. 6), concentrations for the same four 

nutrients probably were elevated because of municipal effluent being discharged into relatively small 

streams with low waste-assimilation capacity. Recent 

(late 1980’s to 1994) concentrations of total-inorganic 

nitrogen, dissolved ammonia, dissolved nitrate, and 

total phosphorus in Long Cane Creek (location 23), 

and in four sites in the headwaters of the Flint River 

(locations 32–35) are about an order-of-magnitude 

less than concentrations shown for 1972–90 water 

years as a result of removing discharges of municipal 

effluent from those stream reaches.

From 1972–90, chronic exposure of aquatic 

organisms to un-ionized ammonia potentially was a 

problem in the Chattahoochee and Flint Rivers 

downstream of wastewater-treatment outfalls for 

Metropolitan Atlanta, and in Long Cane Creek 

downstream of the wastewater-treatment outfall for 

LaGrange. Although chronic exposure criteria for 

ammonia concentrations in surface water were not 

available prior to 1986 (U.S. Environmental 

Protection Agency, 1986), comparison of dissolvedammonia concentration, pH, and water temperature 

data from 1972–90 provides an indication of where 

ammonia concentrations possibly were detrimental to 

aquatic organisms such as fish and invertebrates. At 

least 17 percent of samples at Long Cane Creek near 

West Point (location 23), 7 percent of samples at 

Chattahoochee River at I-285 (location 15), and 3 

percent of samples at Chattahoochee River near 

Fairburn (location 17) exceeded the chronic criteria 

for ammonia toxicity (fig. 25a). In the Upper Flint 

River, at least 23 percent of samples at Flint River 

near Fayetteville (location 33), 9 percent of samples 

at Flint River near Jonesboro (location 32), 2 percent 

of samples at Flint River near Inman (location 34), 

and 0.4 percent of samples at Flint River above 
67

Griffin (location 35) exceeded the chronic criteria for 

ammonia toxicity (fig. 25b). These percentages of 

exceedence are minimums because 1) pH and(or) 

water temperature are not available for all ammonia 

measurements, 2) about 2 percent of available pH 

values are less than 6.5 (the lower limit for which 

criteria apply), and 3) one water temperature is greater 

than 30 ° C (the upper limit for which criteria apply). 

There also are some uncertainties in converting 

criteria for un-ionized ammonia concentrations, the 

principal toxic form of ammonia, to criteria for totalammonia concentrations because the equilibrium of 

un-ionized ammonia and the toxicity of un-ionized 

ammonia changes as pH and temperature change.

From 1972 – 90, total-phosphorus concentrations 

frequently were above recommended concentrations 

to control eutrophication in the Chattahoochee and 

Flint Rivers downstream of wastewater-treatment outfalls for Metropolitan Atlanta and in Long Cane 

Creek downstream of the wastewater-treatment 

outfall for LaGrange. Only two surface-water 

sampling locations (locations 39 and 44) had no total 

phosphorus samples that exceeded the USEPA 

recommendation of 0.1 mg/L as P to control eutrophication in flowing water. Surface-water sampling locations downstream of wastewater-treatment outfalls for 

Metropolitan Atlanta on the Chattahoochee River 

(locations 15, 17, and 19) and the Flint River 

(locations 33, 34, and 35), for LaGrange on Long 

Cane Creek (location 23) exceeded 0.1 mg/L total 

phosphorus more than 95 percent of the time (fig 28).

Increases in dissolved-ammonia and totalphosphorus concentrations that occurred from 

upstream to downstream of major cities and their 

WWTF, significantly decreased in most river reaches 

downstream of major municipal outfall locations from 

Atlanta (locations 15, 17 and 19), Columbus and 

Phenix City (locations 26 – 28), and Albany (locations 

41 and 42) (table 12). Conversion of dissolved 

ammonia to dissolved nitrite and then to dissolved 

nitrate occurs in well-oxygenated surface water 

(nitrification) and is the most likely explanation for 

significant decreases in dissolved-ammonia (fig. 25) 

and significant increases in dissolved-nitrate concentrations (fig. 26). Significant decreases in totalTable 12. Comparison1/ of nutrient concentrations at sampling sites in river reaches downstream of major municipal 

point-source inputs, Apalachicola–Chattahoochee–Flint River basin, 1972–90 water years

[ns, concentrations not significantly different; ↑ , concentration significantly increased between two sites represented by bracket; 

↓, concentration significantly decreased between two sites represented by bracket]

Location 

number

(figure 

16)

Comparison sites

in downstream order

Nutrient constituents

Dissolved 

ammonia

(figure 25)

Dissolved nitrate

(figure 26)

Total 

phosphorus

(figure 28)

Atlanta

15 Chattahoochee River at I-285, at Atlanta, Ga.2/

] ns

] ↓

⎤

⎥ ↓

⎦

] ↑

] ↑

⎤

⎥ ↑

⎦

] ↑

] ↓

⎤

⎥ ns

⎦

17 Chattahoochee River near Fairburn, Ga.

19 Chattahoochee River near Whitesburg, Ga.

Columbus and Phenix City

26 Chattahoochee River - Downstream from Columbus WTF

] ↓

] ↓

⎤

⎥ ↓

⎦

] ns

] ns

⎤

⎥ ↓

⎦

] ns

] ↓

⎤

⎥ ↓

⎦

27 Chattahoochee River - Downstream Oswichee Creek

28 Chattahoochee River - Seaboard Coast Line Railway, Omaha

Albany

41 Flint River near Putney, Ga.

42 Flint River at Newton, Ga. ] ↓ ] ↑ ] ↓

1/ Increases or decreases among three sampling sites were based on results from Kruskal-Wallis tests followed by Mann-Whitney rank-sum tests 

(Inman and Conover, 1983). An increase or decrease between two sampling sites was based on results from Mann-Whitney rank-sum tests. 

The confidence level for significant differences was the 95th percentile. 2/ Chattahoochee River at I-285, at Atlanta, Ga. is downstream of much of the Metropolitan Atlanta area. However, in addition to some of 

Metropolitan Atlanta being downstream, there also are several major wastewater treatment plant discharges to the Chattahoochee River 

downstream of this sampling site.
68

phosphorus concentrations (fig. 28) are probably the 

result of biological uptake of orthophosphate, slow 

hydrolysis of polyphosphates to orthophosphate 

forms, decomposition of organic phosphorus and 

conversion to orthophosphate (Lynard and Field, 

1980), and settling out of phosphorus associated with 

suspended sediment. The pattern of decreasing

dissolved-ammonia and total-phosphorus concentrations continues downstream of Atlanta to upstream of 

Columbus (locations 17 to 19 to 22 to 25), 

downstream of Columbus to the headwaters of the 

Apalachicola River (locations 26 to 27 to 28 to 30 to 

45) and downstream of Albany to the headwaters of 

the Apalachicola River (locations 41 to 42 to 45) 

(figs. 25 and 28).

Exceptions to the above patterns of increases in 

dissolved-nitrate concentrations, and decreases in

dissolved-ammonia and total-phosphorus concentrations in the Atlanta area river reach (table 12) were 

primarily the result of several major WWTF outfalls 

between Chattahoochee River at I-285 (location 15) 

and Chattahoochee River near Fairburn (location 17). 

Although dissolved-nitrate concentrations significantly increased as expected between locations 15 

and 17, dissolved-ammonia concentrations did not 

significantly decrease because additional dissolved 

ammonia was discharged into this reach. Total 

phosphorus was also discharged to the Chattahoochee 

River between locations 15 and 17, which caused the 

significant increase in concentration from location 15 

to 17 and prevented a significant decrease in 

concentration from location 15 to 19. Exceptions to 

the above patterns also occurred in the river reach 

downstream of Columbus and Phenix City (locations 

26 to 28), where concentrations of dissolved nitrate 

significantly decreased (fig. 26a; table 12) rather than 

increased. Although, these sampling sites were 

affected by backwater from Walter F. George 

Reservoir, it is not known why dissolved-nitrate 

concentrations appeared to decrease slightly in this 

river reach. As WWTF in the ACF River basin 

continue to upgrade their facilities, more nitrification 

is likely to occur at WWTF rather than in stream 

reaches downstream from the plants. This could help 

the overall health of stream reaches below effluentdischarge locations by reducing biochemical oxygen 

demand to these reaches, although it would not 

change the nitrogen load to receiving waters.

 Comparisons of nutrient concentrations at 

sampling sites in and downstream of reservoirs in the 

ACF River basin indicate that concentrations were not 

significantly different for over half of the 

comparisons, significantly decreased in 15 comparisons, and significantly increased only downstream of 

Lake Sidney Lanier for total-inorganic nitrogen and 

dissolved nitrate (table 13). It is common for nutrient 

concentrations to be lower in rivers downstream from 

reservoirs than in the reservoirs because of uptake by 

phytoplankton and aquatic plants, denitrification, and 

accumulation of phosphorus associated with sediment 

in reservoirs. Total-phosphorus concentrations significantly decreased downstream in four out of six pairs 

of reservoir data and downstream data (Lake Sidney 

Lanier, West Point Lake, Lake Harding, and the Flint 

River arm of Lake Seminole) (fig. 28; table 13). Four 

nutrient species significantly decreased downstream 

of Walter F. George Reservoir and six nutrient species 

significantly decreased downstream of the Flint River 

arm of Lake Seminole. Lake Blackshear, a fairly 

shallow run-of-the-river reservoir, and the Chattahoochee River arm of Lake Seminole had no 

significant changes between concentrations measured 

in the reservoirs and concentrations measured downstream of the reservoirs.

Total-nitrogen, dissolved-nitrate, total-inorganicnitrogen, dissolved-ammonia, total-phosphorus, and 

dissolved-orthophosphate concentrations significantly 

decreased from the Flint River arm of Lake Seminole 

to the Apalachicola River at Chattahoochee (location 

45); however, nutrient concentrations were very 

similar in the Chattahoochee River arm of Lake 

Seminole to the same location on the Apalachicola 

River (figs. 22, 23, 25, 26, 28, and 29; table 13). 

Total-organic-nitrogen concentrations were similar in 

both arms of Lake Seminole and the Apalachicola 

River at Chattahoochee (fig. 24). Higher nutrient 

concentrations in the Flint River arm of Lake 

Seminole than in the Chattahoochee River arm of 

Lake Seminole may be the result of the large 

percentage of the Middle and Lower Chattahoochee 

River in backwater from reservoirs, the absence of 

reservoirs downstream of Albany until Lake 

Seminole, and nonpoint sources of nutrients from 

intensively farmed areas in the Lower Flint River 

basin. Based on available data, it is not possible to 

determine how much of the decrease in nutrient 

concentrations from the Flint River arm of Lake 

Seminole to the Apalachicola River at Chattahoochee 

resulted from (1) mixing of waters from the 

Chattahoochee and Flint Rivers, (2) changes in 

nutrient concentrations in upstream reservoirs on the 

Chattahoochee River, (3) loss from sedimentation in 

the Flint River arm of Lake Seminole, and (4) 

utilization by aquatic plants. Aquatic weeds are a 

widespread problem throughout Lake Seminole 

(Gholson, 1984a, b).
Table 13. Comparison1/ of nutrient concentrations at sampling sites in and downstream of reservoirs, ApalachicolaChattahoochee-Flint River basin, 1972–90 water years

[–, no available data; ns, concentrations not significantly different; ↓, concentration significantly decreased from the reservoir to 

downstream of the reservoir: ↑ , concentration significantly increased from the reservoir to downstream of the reservoir

Location 

number2/

(figure 16)

Comparison sites 

in downstream order

Nutrient constituents

Total 

nitrogen 

(figure 22)

Totalinorganic 

nitrogen 

(figure 23)

Totalorganic 

nitrogen 

(figure 24)

Dissolved 

ammonia 

(figure 25)

Dissolved 

nitrate 

(figure 26)

Total 

phosphorus 

(figure 28)

Dissovled 

orthophosphate 

(figure 29)

3 Lake Sidney Lanier

Chattahoochee River - 

Gwinnett County Water

Intake

– ↑ – ns ↑ ↓ –

22

West Point Lake

Chattahoochee River at West

Point, Ga.

– – ns ↓ ↓ –

25

Lake Harding

Chattahoochee River -

Columbus Water Intake

– ns – ns ns ↓ –

29 

and 30

Walter F. George 

Reservoir

Chattahoochee River at (and

near) Columbia, Ala.

↓ ↓ ns ↓ ↓ 3/ ns

40

Lake Blackshear

Flint River at Albany, Ga. – ns – ns ns ns –

45

Lake Seminole, 

Chattahoochee arm

Apalachicola River at 

Chattahoochee, Fla.

ns ns ns ns ns ns ns

45

Lake Seminole, Flint arm

Apalachicola River at 

Chattahoochee, Fla.

↓ ↓ ns ↓ ↓ ↓ ↓

69

1/ An increase or decrease between two sampling sites was based on results from Mann-Whiteny rank-sum tests (Inman and 

Conover, 1983). The confidence level for significant differences was the 95th percentile. 2/ Nutrient data for multiple sampling sites within each reservoir were used in statistical comparisons rather than data from a 

single reservoir sampling site. 3/ Comparison between total-phosphorus concentrations in Walter F. George Reservoir and downstream sites were not made 

because total-phosphorus concentrations measured at Chattahoochee River at Columbia from 1975 to 1983 (river mile 

156.7, location 29) were significantly higher than at Chattahoochee River near Columbia from 1982 to 1990 (river mile 

154.3, location 30) (figure 28a). It is not know if total-phosphorus concentrations in the river were different for the two 

periods of record, or if the differeences were due to different sample colleciton techniques and(or) laboratory analyses 

methods used by Alabama Department of Environmental Management (location 29) and the U.S. Geological Survey 

(location 30).

Concentrations of total phosphorus at 

Chattahoochee River at West Point (just below West 

Point Lake; location 22) prior to the beginning of 

storage in West Point Lake (October 16, 1974) and 

after the reservoir reached maximum power pool 

(June 10, 1975) provides a good example of 

reservoirs reducing total-phosphorus concentrations. 

Median and minimum total-phosphorus concentrations decreased from 0.19 and 0.04 mg/L, 

respectively, prior to the beginning of storage in West 

Point Lake (1968–74) to 0.05 and 0.02 mg/L, 

respectively, after the reservoir was in full operation 

(1975–90). Similar changes in concentrations did not 

occur for dissolved ammonia or dissolved nitrate.
70

Discharges from eight tributary streams with 

available nutrient-concentration data have undetectable effects on the nutrient concentrations of the 

receiving mainstem rivers (figs. 22–29). Unlike mainstem sampling sites which have mixed land use within 

their watersheds, Peachtree Creek was almost 99 

percent urban and Snake Creek was about 83 percent 

forested (table 14). The other six tributaries have 

mixed land use including urban components in Big 

Creek, Sweetwater Creek, and Long Cane Creek; a 

dominant agriculture component in Ichawaynochaway Creek and Chipola River; and a dominant forest 

component in Kinchafoonee Creek. Total-inorganicnitrogen and dissolved-nitrate concentrations were 

very low in forest dominated tributaries (Snake and 

Kinchafoonee Creeks) (figs. 23, 26; table 14). The 

four tributaries with an urban component of land use 

(Big, Peachtree, Sweetwater, and Long Cane Creeks) 

had moderate to high concentrations of dissolved 

ammonia, dissolved nitrate (except Sweetwater 

Creek), and total phosphorus (figs. 25, 26, 28). Long 

Cane Creek had very elevated concentrations of these 

three constituents for the period 1972–90; however, 

improvements to the Long Cane Creek WPCP 

including advanced treatment in 1986, phosphorus 

removal in 1994, and relocation of the effluent 

discharge to the Chattahoochee River in 1993 (Anne 

Westmoreland, Long Cane Creek WPCP, oral 

commun., 1994) have resulted in much smaller 

nutrient concentrations in Long Cane Creek. By 

contrast, concentrations of these three nutrient species 

and dissolved orthophosphate (fig. 29) were very low 

in four tributaries with little or no urban land use—

Snake, Kinchafoonee, Ichawaynochaway Creeks, and 

Chipola River—with the exception of moderate to 

high dissolved-nitrate concentrations relative to other 

concentrations in Ichawaynochaway Creek and 

Chipola River in the ACF River basin. Agriculture 

was the predominant land use in Ichawaynochaway 

Creek and Chipola River and elevated dissolvednitrate concentrations in these two tributaries may be 

from inflow of ground water with elevated dissolvednitrate concentrations.

Organic-nitrogen-concentration data were 

available for only a limited number of sites, so it is 

not clear if downstream changes in concentrations of 

total-organic nitrogen (fig. 24) or dissolved-organic 

nitrogen (fig. 27) occurred within the study area. 

Dissolved-orthophosphate concentrations (fig. 29) 

were about an order-of-magnitude higher at 

Chattahoochee River near Fairburn and near 

Whitesburg (locations 17 and 19), downstream from 

Atlanta, than at other locations in the ACF River 

basin. More than half of the dissolved-orthophosphate 

concentrations were below the reporting limit of 0.02 

mg/L at 11 of 14 surface-water sampling sites where it 

was measured routinely. Dissolved-orthophosphate 

concentrations were less than the reporting limit for 

all data from the Chattahoochee River arm of Lake 

Seminole and for about 75 percent of data from the 

Flint River arm of Lake Seminole.

Two sampling sites on the Chattahoochee River 

are located within 2.4 river miles of each other and 

have non-overlapping periods of record. Distribution 

of dissolved-nitrate concentrations (fig. 26a) were 

very similar, but total-phosphorus concentrations (fig. 

28a) measured at Chattahoochee River at Highway 52 

from 1975 to 1983 (river mile 156.7, location 29) 

were significantly higher than at Chattahoochee River 

near Columbia from 1982 to 1990 (river mile 154.3, 

location 30). It is not known if total-phosphorus 

concentrations in the river were different for the two 

periods of record, or if the differences were because 

of different sample collection techniques and(or) 

laboratory analyses methods used by ADEM (location 

29) and the USGS (location 30).

Seasonal variations in concentrations

Nutrient concentrations in streams and reservoirs within the ACF River basin can vary seasonally 

because of seasonal changes in growth and decay of 

vegetation (particularly in the Apalachicola floodplain; Mattraw and Elder, 1984), changes in temperature which in turn effects phytoplankton growth in 

reservoirs (Cherry and others, 1978), nitrification of 

ammonia to nitrate (Ehlke, 1978); seasonal 

applications of fertilizers; and other environmental 

factors. Dissolved-ammonia, dissolved-nitrate, and 

total-phosphorus concentrations were plotted by time 

of year for surface-water samples collected during 

1972–90 water years. Seasonal variations or lack of 

seasonal variations are highlighted by LOWESS lines 

for nine stream- and reservoir-sampling sites along 

the Chattahoochee River (figs. 30–32) and for six 

stream- and reservoir-sampling sites along the Flint 

River, one site on the Chipola River, and one site near 

the mouth of the Apalachicola River (figs. 33 to 35).

In the ACF River basin, summer decreases in 

concentrations of nutrients in reservoirs, and stream 

sites directly affected by reservoirs, were related to 

seasonality of phytoplankton production in reservoirs. 

In late spring, water temperatures, and therefore, 

phytoplankton growth rates, begin to increase. 

Phytoplankton utilize dissolved nitrogen for cell 

growth; and thus, convert dissolved nitrogen to 

particulate form until cells die and break apart. As
71

Table 14. Land use and land cover, median nutrient concentrations, and mean annual yield for eight tributary streams, 

Apalachicola–Chattahoochee–Flint River basin, 1972–90 water years

[–, no available data; <, less than]

Location 

number 

(figure 

16)

Tributary stream

Land use and land 

cover1/, in percent

Median nutrient concentration2/, in milligrams per liter

(mean annual yield, in tons per square mile of drainage area)

Urban Agricultural Forest

Total 

nitrogen 

(figure 

22)

Totalinorganic 

nitrogen

(figure 23)

Totalorganic 

nitrogen 

(figure 24)

Dissolved 

ammonia 

(figure 25)

Dissolved 

nitrate 

(figure 26)

Dissolvedorganic 

nitrogen 

(figure 27)

Total 

phosphorus 

(figure 28)

Dissolved 

orthophosphate 

(figure 29)

Urban

12 Peachtree Creek 99 0 1 –

(–)

0.67

(1.0)

–

(–)

0.13

(0.23)

0.52

(0.78)

–

(–)

0.08

(0.30)

–

(–)

Mixed, Urban

16 Sweetwater Creek 24 23 51 –

(–)

0.31

(0.55)

–

(–)

0.06

(0.16)

0.25

(0.34)

–

(–)

0.05

(0.17)

–

(–)

5 Big Creek 18 24 57 –

(–)

0.67

(1.0)

–

(–)

0.07

(0.11)

0.55

(0.72)

–

(–)

0.07

(0.15)

–

(–)

23 Long Cane Creek 12 19 68 –

(–)

1.06

(–)

–

(–)

0.31

(–)

0.48

(–)

–

(–)

0.74

(–)

–

(–)

Mixed, Agricultural

44 Ichawaynochaway 

Creek

1 52 36 1.0

(–)

0.46

(–)

0.41

(–)

0.02

(–)

0.44

(–)

0.35

(–)

0.03

(–)

<0.02

(–)

47 Chipola River 2 50 39 0.93

(1.9) 

0.67

(1.3)

0.26

(0.74)

0.02

(0.06)

0.62

(1.2)

0.17

 (–)

0.03

(0.07)

<0.02

(0.03)

Mixed, Forest

39 Kinchafoonee 

Creek

<1 32 62 0.57

(–)

0.16

(–)

0.41

(–)

0.04

(–)

0.13

(–)

0.28

(–)

0.03

(–)

<0.02

 (–)

Forest

18 Snake Creek 1 16 83 0.40

(–)

0.20

 (–)

0.28

 (–)

0.02

 (–)

0.15

 (–)

0.16

 (–)

0.02

(–)

<0.02

 (–)

1/ 1972–78; percentages do not add up to 100 because rangeland, wetland, water, and barren land are not listed. 2/ Subset of 1972–90 water years, see tables 10 and 16 for exact years.

part of the Upper Chattahoochee River Quality 

Assessment, it was observed that concentrations of 

phytoplankton (diatoms, green algae, and blue-green 

algae) increased as water temperatures increased at all 

four sites sampled in West Point Lake; and 

biologically available nutrients, as measured by algal 

growth potential assays, decreased in response to 

increased phytoplankton concentrations (Cherry and 

others, 1978, p. 5, 19).

Seasonal variations in nutrient concentrations in 

the Chattahoochee River are strongly influenced by 

the 13 reservoirs on the river, particularly in the reach 

of the river from West Point Lake to Lake Seminole. 

Dissolved-nitrogen concentrations were generally 

lower in warm, summer months from the inflow of 

West Point Lake (location 20) to Lake Seminole 

(location 31) for ammonia (fig. 30) and from the 

center of West Point Lake (location 21) to Lake

Seminole for nitrate (fig. 31). Total-phosphorus 

concentrations also seems to be lower in summer and 

early fall in the Middle and Lower Chattahoochee 

River (fig. 32), although the pattern is not as 

pronounced as for dissolved ammonia and dissolved 

nitrate. However, in the Upper Chattahoochee River, 

it is difficult to identify seasonal variations in nutrient 

concentrations in Lake Sidney Lanier (location 2) 

because the frequency of nutrient-data collection was 

quarterly. It is not known if the late-summer early-fall 

peak in dissolved-nitrate concentrations at Chattahoochee River at the Gwinnett County Water Intake 

(location 3) (fig. 31) mirrored seasonal variation in 

Lake Sidney Lanier or was the result of changes in 

dissolved-nitrate concentrations in the 23 mi reach 

between the Lake Sidney Lanier and the Gwinnett 

County sampling sites.
10

1

0.100.01

10

1

0.100.01

10

1

0.100.01

DISSOLVED-AMMONIA CONCENTRATION AS N, IN MILLIGRAMS PER LITER

Chattahoochee RiverSR 369, Brown's Bridge, Ga.(location 2, Figure 16)Lake Sidney Lanier 

Chattahoochee River,Gwinnett County Water Intake, Ga.(location 3)

Chattahoochee River at Franklin, Ga.(location 20)inflow to West Point Lake

Chattahoochee River,LaGrange Water Intake, Ga.(location 21)West Point Lake 

Chattahoochee River,Columbus Water Intake, Ga.(location 25)

Chattahoochee River,Seaboard Coastline Railroad, Omaha, Ga.(location 28)Walter F. George Reservoir

Chattahoochee River near (location 17)Chattahoochee River,upstream from Bartletts Fe(location 24)Lake Harding

Chattahoochee River near (location 31)inflow to Lake Seminole

J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J 

Figure 30. Seasonal variation in dissolved-ammonia concentrations for selected streams and reservoirs, Chattahooch1972–90 water years.

STREAM RESERV

Data collected at quarterly intervals werenot adequate for seasonal smoothing.

EXPLANATION

LOWESS LINE CENSORING LIMIT

72
10

1

0.100.01

10

1

0.100.01

10

1

0.100.01

DISSOLVED-NITRATE CONCENTRATION AS N, IN MILLIGRAMS PER LITER

Chattahoochee RiverSR 369, Brown's Bridge, Ga.(location 2, Figure 16)Lake Sidney Lanier 

Chattahoochee River,Gwinnett County Water Intake, Ga.(location 3)

Chattahoochee River at Franklin, Ga.(location 20)inflow to West Point Lake

Chattahoochee River,LaGrange Water Intake, Ga.(location 21)West Point Lake

Chattahoochee River,Columbus Water Intake, Ga.(location 25)

Chattahoochee River,Seaboard Coastline Railroad, Omaha, Ga.(location 28)Walter F. George Reservoir

Chattahoochee River near (location 17)Chattahoochee River,upstream from Bartletts Fe(location 24)Lake Harding

Chattahoochee River near (location 31)inflow to Lake Seminole

J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J 

Figure 31. Seasonal variation in dissolved-nitrate concentrations for selected streams and reservoirs, Chattahoochee 1972–90 water years.

Data collected at quarterly intervals werenot adequate for seasonal smoothing.

STREAM RESERVOIR

EXPLANATION

LOWESS LINE

73
10

1

0.100.01

10

1

0.100.01

10

1

0.100.01

TOTAL-PHOSPHORUS CONCENTRATION AS P, IN MILLIGRAMS PER LITER

Chattahoochee RiverSR 369, Brown's Bridge, Ga.(location 2, Figure 16)Lake Sidney Lanier 

Chattahoochee River,Gwinnett County Water Intake, Ga.(location 3)

Chattahoochee River at Franklin, Ga.(location 20)inflow to West Point Lake

Chattahoochee River,LaGrange Water Intake, Ga.(location 21)West Point Lake 

Chattahoochee River,Columbus Water Intake, Ga.(location 25)

Chattahoochee River,Seaboard Coastline Railroad, Omaha, Ga.(location 28)Walter F. George Reservoir

Chattahoochee River near (location 17)Chattahoochee River,upstream from Bartletts Fe(location 24)Lake Harding

Chattahoochee River near (location 31)inflow to Lake Seminole

J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J 

Figure 32. Seasonal variation in total-phosphorus concentrations for selected streams and reservoirs, Chattahoochee 1972–90 water years.

Data collected at quarterly intervals werenot adequate for seasonal smoothing.

STREAM RESERVO

EXPLANATION

LOWESS LINE CENSORING LIMIT

74
Figure 33. Seasonal variation in dissolved-ammonia concentrations for selected streams and reservoirs, Flint, Chipola, a

Rivers, 1972–90 water years. (Locations 33, 35, and 37 are plotted with 4-log cycle scales.)

J F M A M J J A S O N D J F M A M J J A S O N D

LOWESS LINE

CENSORING 

STREAM

RESERVOIR

DISSOLVED-AMMONIA CONCENTRATION AS N, IN MILLIGRAMS PER LITER 10

1

0.100.01

10

1

0.100.01

Flint River near Fayetteville, Ga.(location 33, Figure 16)) Flint River above Griffin, Ga. (location 35) Flint River at Montezuma, Ga. (location 37)Flint River near Vienna, Ga.(location 38)inflow to Lake Blachshear

Flint River near Putney, Ga.(location 41)

Flint River below Bainbridge, Ginflow to Lake Seminole

Chipola River near Altha, Fla.(location 47)

Apalachicola RiverBuoy 40, Mile 11A, Fla.(location 46)

100

10

1.00.1

0.01

J F M A M J J 

EXPLANATION

75
Figure 34. Seasonal variation in dissolved-nitrate concentrations for selected streams and reservoirs, Flint, Chipola, an

Apalachicola Rivers, 1972–90 water years.

J F M A M J J A S O N D J F M A M J J A S O N D

DISSOLVED-NITRATE CONCENTRATION AS N, IN MILLIGRAMS PER LITER 10

1

0.100.01

10

1

0.100.01

10

1

0.100.01

J F M A M J 

Flint River near Fayetteville, Ga.(location 33, Figure 16) Flint River above Griffin, Ga. (location 35) Flint River at Montezum

(location 37)

Flint River near Vienna, Ga.(location 38)inflow to Lake Blackshear 

Flint River near Putney, Ga.(location 41)

Flint River below Bainbinflow to Lake Seminol

Chipola River near Altha, Fla.(location 47)

Apalachicola RiverBuoy 40, Mile 11A, Fla.(location 46)

LOWES

STREAM

RESER

EXPLANATIO

76
Figure 35. Seasonal variation in total-phosphorus concentrations for selected streams and reservoirs, Flint, Chipola, and 

1972–90 water years.

J F M A M J J A S O N D J F M A M J J A S O N D

TOTAL-PHOSPHORUS CONCENTRATION AS P, IN MILLIGRAMS PER LITER 10

1

0.100.01

10

1

0.100.01

10

1

0.100.01

J F M A M J J 

Flint River near Fayetteville, Ga.(location 33, Figure 16)

Flint River above Griffin, Ga.(location 35)

Flint River at Montezuma, Ga(location 37)

Flint River near Vienna, Ga.(location 38) inflow to Lake Blackshear Flint River near Putney, Ga. (location 41) Flint River below Bainbridge, 

inflow to Lake Seminole

Chipola River near Altha, Fla.(location 47)

Apalachicola River,Buoy 40, Mile 11A, Fla.(location 46)

LOWESS LI

CENSORING 

STREAM

RESERVOIR

EXPLANATION

77
78

In contrast to the Chattahoochee River, seasonal 

patterns in nutrient concentrations in the Flint, 

Chipola, and Apalachicola Rivers either were not 

present or were less apparent (figs. 33–35). In the 

Chattahoochee River, reservoirs seem to control 

seasonal variations; however, in the Flint, Chipola, 

and Apalachicola Rivers, which have few reservoirs, 

there may be several factors influencing seasonal 

variation of nutrient concentrations offsetting one 

another.

Temporal trends in concentrations

Nutrient data from 47 sampling sites were 

analyzed for trends (table 15, fig. 36). Three sites on 

the Chattahoochee River were affected by backwater 

(locations 26, 27, and 28) and seven sites were located 

in reservoirs (locations 2, 20, 21, 24, 31, 38, and 43). 

The period of record for trend tests were 1980–90 

water years at all sites so that comparisons among 

trends at different sites would be valid. The period 

1980–90 was chosen because more sites within the 

ACF River basin had available nutrient data for that 

time period than longer periods, and the 1980–90 time 

period is of interest for comparison of results across 

the nation (Dennis Helsel, U.S. Geological Survey, 

written commun., 1993). From the late 1980’s to 

1993, improvements to several WWTF and phosphate 

detergent bans resulted in decreased nutrient 

concentrations (especially in the Upper and Middle 

Chattahoochee River subbasins) which were not 

reflected in the results of 1980–90 trend tests 

(Wangsness and others, 1994; DeVivo and others, 

1995).

Seasonal Kendall test (Hirsch and others, 1982), 

a nonparametric or distribution free test, was used to 

determine if changes in concentrations of seven 

nutrient constituent groups were generally increasing 

or decreasing at each surface-water site. The test 

compares concentrations in each month with concentrations in that same month in other years or by 

seasons when data are collected less frequently than 

monthly. The 12 monthly tests (or fewer seasonal 

tests) are combined to form an overall test for trend 

(Helsel, 1993, p. 98). This enables trends over several 

years to be more easily separated from seasonal 

variations in nutrient water quality. Trends in flowadjusted concentrations also were calculated to test 

for trends caused by factors other than streamflow 

(such as from point-source loads and nonpoint-source 

inputs). Flow-adjusted concentrations were determined by first constructing a LOWESS line to 

represent the relation between nutrient concentration 

and streamflow, and then by calculating a residual, 

which is the difference between concentrations from 

the LOWESS line and the measured concentration 

(Hirsch and others, 1991). As long as the relation 

between concentration and streamflow has not 

changed during the period of the trend test, a trend in 

residuals implies a trend in concentration independent 

of streamflow conditions (Helsel, 1993, p. 98). A 90-

percent confidence level was used for all trend results.

Sites where trends were calculated have a 

minimum of eight years of quarterly nutrient data, and 

at least one-half of nutrient analyses were from 

samples collected in the first and last third of the 

1980–90 period (Lanfear and Alexander, 1990). Data 

were insufficient to calculate trends for dissolvedorganic nitrogen at all sites. Flow-adjusted trends are 

not reported for reservoir sites, three sites in the 

Chattahoochee River affected by backwater, and 

tributary sites in the Metropolitan Atlanta area 

sampled as a part of the DeKalb County monitoring 

network because streamflow data were not available. 

Table 15 lists all surface-water sites where trends 

were calculated; positive or negative trends, where 

significant; and rate of change in concentration, in 

milligrams per liter per year (mg/L/yr). Figure 36 

shows the locations where trends in concentrations (as 

opposed to trends in flow-adjusted concentrations) 

were calculated for dissolved ammonia, dissolved 

nitrate, and total phosphorus; and the direction of 

trends, if significant.

All significant trends in nutrient concentrations in 

the Chattahoochee River were increasing, except 

dissolved ammonia (fig. 36) and total-inorganicnitrogen trends (table 15), which decreased at several 

sites in the reach downstream of Atlanta and downstream of Columbus and Phenix City. All significant 

trends in nutrient concentrations at sites on the Upper 

Flint River were decreasing, and at a larger rate of 

change than in other reaches in the ACF River basin. 

Most changes in nutrient concentrations in the Upper 

Flint River basin were the result of diverting 

discharges of municipal-wastewater effluent to the 

Chattahoochee River, the South River (outside the 

ACF River basin), and to land application areas. All 

significant trends in the Middle and Lower Flint River 

basins were increasing, except the trend in dissolvedammonia concentration, which decreased at Flint 

River near Putney (location 41). All significant trends 

in the Apalachicola River were decreasing, except the 

trend in dissolved-nitrate concentration at Apalachicola River, Buoy 40, mile 11A (location 46). At 

sites on the Chattahoochee and Flint Rivers 

downstream of Atlanta and Albany, decreasing trends 

in dissolved-ammonia concentration and increasing 

trends in dissolved-nitrate concentration were the 

result of improved wastewater treatment at WWTF in 

these urban areas.
79

Table 15. Trend-test results for nutrient concentrations for selected surface-water sampling sites, by subbasin, Apalachicola–Chattahoochee

90 water years

[All trends are results of seasonal Kendall tests for time trends from 1980–90 water years. Data were insufficient to calculate trends for dissolved-organic n

Apalachicola–Chattahoochee–Flint River basin. C, concentration; FAC, flow-adjusted concentration; —, trend test could not be performed 

Surface-water station name sources: D, DeKalb County, Georgia; F, Florida Department of Environmental Regulation; G, Georgia Environmental Protection Geological Survey]

Location 

number 

(figure 16)

Surface-water station name

(Reservoir name, if applicable)

Average rate of change, 1980–90 water years, in milligrams per liter p

Total nitrogen Total-inorganic nitrogen Total-organic nitrogen Dissolved ammonia Dissolved nitrate 

p

C FAC C FAC C FAC C FAC C FAC 

Upper Chattahoochee (03130001)

1 Chattahoochee River near Cornelia, Ga.U — — +.020 +.021 — — +.008 +.002 +.013 +.013 +.2 Chattahoochee River - Georgia Highway 369, Browns 

 BridgeG (Lake Sidney Lanier)

— —

1/ 2/

— — +.007 2/ 1/ 2/ 

3 Chattahoochee River - Gwinnett County Water IntakeG — — +.003 +.005 — — +.003 +.002 +.003 +.006 4 Chattahoochee River - DeKalb County Water IntakeG — — +.008 +.009 — — +.003 +.002 +.005 +.007 5 Big Creek - Roswell Water IntakeG — — +.089 +.088 — — +.003 +.003 +.080 +.077 +.6 Chattahoochee River - Cobb County Water IntakeG — — +.026 +.021 — — 1/ 1/ +.023 +.019 +.7 Chattahoochee River - Atlanta Water IntakeG — — +.026 +.021 — — +.003 +.002 +.025 +.019 +.8 North Fork Peachtree Creek - Pleasantdale Road near DoravilleD — — 1/ 2/ — — 1/ 2/ 1/ 2/ +.9 Arrow Creek - Plaster Road near Peachtree-DeKalb AirportD — — 1/ 2/ — — +.015 2/ 1/ 2/ +.

10 North Fork Peachtree Creek - U.S. Highway 23D — — — — — — 1/ 2/ 1/ 2/ +.11 South Fork Peachtree Creek - Johnson Road in AtlantaD — — — — — — — — 1/ 2/ +.12 Peachtree Creek at Atlanta, Ga.U — — 1/ +.011 — — 1/ 1/ 1/ +.009 +.13 Nancy Creek - bridge 0.2 miles downstream from 

 Chamblee-Dunwoody Road D

— — — — — — +.009 2/ — — +.

14 Nancy Creek - at Johnsons Ferry Road near ChambleeD — — — — — — 1/ 2/ — — 

Middle Chattahoochee—Lake Harding (03130002)

15 Chattahoochee River at I-285, at Atlanta, Ga.U — — 1/ 1/ — — 1/ –.014 +.035 +.022 +.16 Sweetwater Creek near Austell, Ga.U — — 1/ 1/ — — +.004 +.002 1/ 1/ 17 Chattahoochee River near Fairburn, Ga.U 1/ 1/ +.040 +.037 1/ 1/ 1/ –.012 +.043 +.046 +.
80

19 Chattahoochee River near Whitesburg, Ga.U — — +.080 +.035 — — 1/ –.010 +.090 +.045 +20 Chattahoochee River at Franklin, Ga.U (inflow to West Point Lake) — — +.048 2/ — — –.005 2/ +.045 2/ +21 Chattahoochee River - LaGrange Water IntakeG (West Point Lake) — — +.042 2/ — — 1/ 2/ +.030 2/ +22 Chattahoochee River at West Point, Ga.U — — 1/ 1/ — — 1/ 1/ 1/ 1/ +23 Long Cane Creek near West Point, Ga.U — — +.042 1/ — — –.023 1/ +.078 +.078 24 Chattahoochee River - Upstream from Bartletts Ferry 

 DamG (Lake Harding)

— — +.010 2/ — — +.003 2/ +.008 2/ +

Middle Chattahoochee—Walter F. George Reservoir (03130003)

25 Chattahoochee River - Columbus Water IntakeG — — 1/ 1/ — — 1/ 1/ 1/ 1/ +26 Chattahoochee River - Downstream from Columbus WTFG

 (affected by backwater from Walter F. George Reservoir)

— — –.013 2/ — — –.015 2/ 1/ 2/ 

27 Chattahoochee River - Downstream Oswichee CreekG

 (affected by backwater from Walter F. George Reservoir)

— — –.007 2/ — — –.008 2/ 1/ 2/ 

28 Chattahoochee River - Seaboard Coast Line Railway, OmahaG

 (affected by backwater from Walter F. George Reservoir)

— —

1/ 2/

— —

1/ 2/ 1/ 2/ +

Lower Chattahoochee (03130004)

31 Chattahoochee River near Steam Mill, Ga.U (inflow to 

 Lake Seminole, Chattahoochee Arm)

— — +.010 2/ — — +.004 2/ 1/ 2/ +

Upper Flint (03130005)

32 Flint River near Jonesboro, Ga.U — — –.272 –.279 — — –.058 –.061 –.139 –.145 –33 Flint River near Fayetteville, Ga.U — — –.349 –.332 — — –.068 –.096 –.116 –.114 –34 Flint River near Inman, Ga.U — — –.130 –.134 — — –.010 –.011 –.097 –.092 –

Table 15. Trend-test results for nutrient concentrations for selected surface-water sampling sites, by subbasin, Apalachicola – Chattahooche 90 water years—Continued[All trends are results of seasonal Kendall tests for time trends from 1980 – 90 water years. Data were insufficient to calculate trends for dissolved-organic Apalachicola – Chattahoochee – Flint River basin. C, concentration; FAC, flow-adjusted concentration; —, trend test could not be performed Surface-water station name sources: D, DeKalb County, Georgia; F, Florida Department of Environmental Regulation; G, Georgia Environmental Protectio

Geological Survey]

Location 

number 

(figure 16)

Surface-water station name

(Reservoir name, if applicable)

Average rate of change, 1980 – 90 water years, in milligrams per liter 

Total nitrogen Total-inorganic nitrogen Total-organic nitrogen Dissolved ammonia Dissolved nitrate 

C FAC C FAC C FAC C FAC C FAC 
81

35 Flint River above Griffin, Ga.U –.113 –.111 –.082 –.090 –.016 –.016 –.003 –.003 –.077 –.080 –

Middle Flint (03130006)

37 Flint River at Montezuma, Ga.U — — +.008 +.010 — — +.003 +.002 +.007 +.008 +38 Flint River near Vienna, Ga.U (inflow to Lake Blackshear) — — +.015 2/ — — +.001 2/ +.010 2/ +

Lower Flint (03130008)

40 Flint River at Albany, Ga.U — — 1/ 1/ — — 1/ 1/ 1/ 1/ 41 Flint River near Putney, Ga.U — — 1/ 1/ — — –.011 –.011 +.016 +.013 43 Flint River below Bainbridge, Ga.U (inflow to Lake Seminole, 

 Flint Arm)

— — +.016 2/ — — 1/ 2/ +.017 2/ 

Apalachicola (03130011)

45 Apalachicola River at Chattahoochee, Fla.U 1/ 1/ 1/ 1/ 1/ 1/ 1/ 1/ 1/ 1/ –46 Apalachicola River, Buoy 40, mile 11AF 1/ 1/ 1/ 1/ 1/ 1/ –.002 1/ +.010 1/ –

Chipola (03130012)

47 Chipola River near Altha, Fla.U 1/ 1/ 1/ 1/ 1/ 1/ –.003 2/ 1/ 1/ 

1/ Trends were calculated, but were not significant at the 90-percent confidence level. 2/ Data could not be flow adjusted. 3/ Trends were significantly increasing at the 90-percent confidence level; however, average rates of change could not be calculated because of high perce4/ Trends were significantly decreasing at the 90-percent confidence level; however, average rates of change could not be calculated because of high perc

Table 15. Trend-test results for nutrient concentrations for selected surface-water sampling sites, by subbasin, Apalachicola – Chattahooche 90 water years—Continued[All trends are results of seasonal Kendall tests for time trends from 1980 – 90 water years. Data were insufficient to calculate trends for dissolved-organic nApalachicola – Chattahoochee – Flint River basin. C, concentration; FAC, flow-adjusted concentration; —, trend test could not be performed 

Surface-water station name sources: D, DeKalb County, Georgia; F, Florida Department of Environmental Regulation; G, Georgia Environmental Protectio

Geological Survey]

Location 

number 

(figure 16)

Surface-water station name

(Reservoir name, if applicable)

Average rate of change, 1980 – 90 water years, in milligrams per liter 

Total nitrogen Total-inorganic nitrogen Total-organic nitrogen Dissolved ammonia Dissolved nitrate 

C FAC C FAC C FAC C FAC C FAC 
30

31

33

34

84

o

o

o

85o

32o

o

o

30

31

33

34

84

o

o

o

85o

32o

o

o

30

33

34

84

o

o

o

85o

o

o

o

3

19 33

34

20

21

17

6

15

13

2

23

24

26

43

46

45

31

25

35

32

22

47

27

28

16

5

37

38

41

1

14

4

8

1110

9

40

7 12

3

19 33

34

20

21

17

6

15

2

23

24

26

43

46

45

31

25

35

32

22

47

27

28

7 16

9

11

5

37

38

41

1

12

40

4

8 10

3

19 33

34

20

21

17

6

2

23

24

26

43

46

45

31

25

35

32

22

47

27

28

16

5

37

38

41

1

40

4

8

109 15

14

7 12

13

Dissoved ammonia Dissoved nitrate Total phosphorus

 EXPLANATION

CONCENTRATION TREND (TABLE 15)

 AND LOCATION NUMBER

 Upward

 None

 Downward

Base from U.S. Geological Survey digital files

Figure 36. Summary of trends for concentration of dissolved ammonia, dissolved nitrate, and total 

phosphorus in surface water, Apalachicola-Chattahoochee-Flint River basin, 1980-90 water years.

35

3

40

82
83

Increasing trends in total-phosphorus 

concentrations are an accurate representation of 

temporal changes in this constituent for the period 

1980–90. However, in February 1989, the Georgia 

Environmental Protection Division issued an 

Administrative Order requiring all major WWTF 

(larger than 1 Mgal/d) between Lake Sidney Lanier 

(upstream of Atlanta) and West Point Lake 

(downstream of Atlanta) to reduce average 

concentration of phosphorus in effluent to 0.75 mg/L 

or less. By 1993, nine municipal and one industrial 

WWTF were in compliance of the Order (David 

Kamps, Georgia Environmental Protection Division, 

oral commun., 1994). The three remaining WWTF in 

this reach of the Chattahoochee River are owned by 

the city of Atlanta, which negotiated an extension 

until July 4, 1996, in exchange for agreeing to meet a 

more restrictive limit of 0.64 mg/L average 

phosphorus concentration. Point-source loads of 

phosphorus from the 13 major WWTF that discharge 

into the Chattahoochee River between Buford Dam 

and West Point Lake decreased from a high of 1,670 

tons in 1988 to 298 tons in 1993 (David Kamps, 

Georgia Environmental Protection Division, written 

commun., 1994). This large decrease in point-source 

loads was primarily the result of legislated restrictions 

on use of phosphate detergents and improvements to 

WWTF. Restrictions of the use of phosphate 

detergents decreased phosphate concentrations of 

influent to WWTF and helped improve efficiency of 

phosphorus removal within the WWTF (DeVivo and 

others, 1995). Total-phosphorus loads upstream of 

Metropolitan Atlanta (Chattahoochee River–Gwinnett 

County Water Intake; location 3) continued to 

increase from 47 tons in 1988 to 200 tons in 1993, 

because of increases in nonpoint-source inputs. 

Although volume of effluent discharged continued to 

increase, total-phosphorus loads downstream from 

Metropolitan Atlanta (Chattahoochee River near 

Whitesburg; location 19) peaked at 1,760 tons in 

1984, and decreased from 1,190 tons in 1988 to 550 

tons in 1993, primarily because of the large decrease 

in point-source loads (Wangsness and others, 1994).

In addition to statistical trend tests, time-series 

plots of nutrient concentrations can provide additional 

information on temporal variability at individual 

water-quality sites and among sites. Time-series plots 

of dissolved-ammonia, dissolved-nitrate, and totalphosphorus concentrations, LOWESS lines, and 

results of trend tests are shown in figures 37–39 for 

eight river and reservoir sites in the Chattahoochee 

River basin. Concentration data were used in these 

figures rather than residuals of flow-adjusted 

concentrations so direct comparisons could be made 

between river and reservoir sites (flow-adjusted trend 

results cannot be calculated for reservoirs). Trends 

were calculated using data for the period 1980–90 to 

be consistent nationally; however, LOWESS lines 

were calculated using data for the period 1972–90 to 

be consistent with data presented in this report. 

Chattahoochee River near Steam Mill (location 31) is 

an example of a site having an increasing trend in

dissolved-ammonia concentrations and Chattahoochee River at Franklin (location 20) is an example 

of a decreasing trend site (fig. 37). All trends in

dissolved-nitrate concentration on the Chattahoochee 

River either were increasing or not significant at the 

90-percent confidence level (table 15, fig. 38). Trend 

rates in dissolved-nitrate concentrations increased 

moderately (+ 0.045 to + 0.090 mg/L/yr) during 

1980–90 at sites in the stream reach downstream of 

Atlanta, including sites at Fairburn (location 17), near 

Whitesburg (location 19), and at Franklin (location 

20; fig. 38). Although, trends in total-phosphorus 

concentration for the period 1980–90 in the 

Chattahoochee River either were increasing or 

insignificant, the beginning of the decrease in totalphosphorus concentrations in the late 1980’s was 

apparent on the Chattahoochee River downstream of 

Atlanta near Fairburn (location 17), at Franklin 

(location 20), and at the LaGrange Water Intake 

(location 21; fig. 39).

Time-series plots of dissolved-ammonia, 

dissolved-nitrate, and total-phosphorus concentrations, LOWESS lines, and results of trend tests are 

shown in figures 40–42 for eight river and reservoir 

sites in the Flint and Apalachicola River basins. The 

largest rates of change in 1980–90 concentrations for 

all nutrient constituent groups occurred in the Upper 

Flint River subbasin, because of the removal of 

municipal-wastewater outfalls from the Upper Flint 

River basin in the early- to mid-1980’s. For example, 

at Flint River near Fayetteville (location 33)

dissolved-ammonia concentrations decreased an 

average of –0.068 (concentration) and –0.096 (flow 

adjusted) mg/L/yr (fig. 40), and total-phosphorus 

concentrations decreased an average of –0.094 (concentration) and –0.089 (flow adjusted) mg/L/yr (fig. 

42). Upstream at Flint River near Jonesboro (location 

32), dissolved-nitrate concentrations decreased an 

average of –0.139 (concentration) and –0.145 (flow 

adjusted) mg/L/yr (table 15). Trends in dissolvedammonia, dissolved-nitrate, and total-phosphorus 

concentrations were slightly increasing at Flint River 

at Montezuma (location 37) and Lake Blackshear 

(location 38, table 15, figs. 40–42). The patterns of 
Chattahoochee River, 

SR 369, Brown's Bridge, Ga. (location 2, Figure 16) Lake Sidney Lanier

10

1

0.1

0.01

10

1

0.1

0.01

10

1

0.1

0.01

C

Chattahoochee River near Fair(location 17)

Chattahoochee River,Gwinnett County Water Intake, Ga.(location 3)

Chattahoochee River,LaGrange Water Intake, Ga.(location 21)West Point Lake 

Chattahoochee River at Franklin, Ga.(location 20)inflow to West Point Lake

Chattahoochee River,Columbus Water Intake, Ga.(location 25)

Chattahoochee River,Seaboard Coastline Railroad, Omaha, Ga.(location 28)Walter F. George Reservoir

Chattahoochee River near Ste(location 31)inflow to Lake Seminole

Chattahoochee River,upstream from Bartletts Ferry (location 24)Lake Harding .

.

. C

EXPLANATION

1980-90 TREND IN CONCENTRATION (C) OR FLOW-ADJUSTED CONCENTRATION (FAC) LOWESS LINE

CENSORING LIM

DISSOLVED-AMMONIA CONCENTRATION AS N, IN MILLIGRAMS PER LITER

Increasing Decreasing None

Figure 37. Temporal variation in dissolved-ammonia concentrations for selected streams and reservoirs and 1980-90 tRiver,1972–90 water years. (See table 15 for more information on trends.)

1970 1975 1980 1985 1990 1970 1975 1980 1985 1990 1970 1975 1980 

C 

C C,

. C, . FAC

FAC

84
Chattahoochee River, 

SR 369, Brown's Bridge, Ga. (location 2, Figure 16) Lake Sidney Lanier

10

1

0.1

0.01

10

1

0.1

0.01

10

1

0.1

0.01

Chattahoochee River near (location 17)

Chattahoochee River,Gwinnett County Water Intake, Ga.(location 3)

Chattahoochee River,LaGrange Water Intake, Ga.(location 21)West Point Lake

Chattahoochee River at Franklin, Ga(location 20)inflow to West Point Lake

Chattahoochee River,Columbus Water Intake, Ga.(location 25)

Chattahoochee River,Seaboard Coastline Railroad, Omaha, Ga.(location 28)Walter F. George Reservoir

Chattahoochee River near S(location 31)inflow to Lake Seminole

Chattahoochee River,upstream from Bartletts Fe(location 24)Lake Harding

. C, . FAC

. C

DISSOLVED-NITRATE CONCENTRATION AS N, IN MILLIGRAMS PER LITER

Figure 38. Temporal variation in dissolved-nitrate concentrations for selected streams and reservoirs and 1980-90 treRiver, 1972–90 water years. (See table 15 for more information on trends.)

1970 1975 1980 1985 1990 1970 1975 1980 1985 1990 1970 1975 198

C

C

FAC

C, FAC

. C 

.

EXPLANATION

1980-90 TREND IN CONCENTRATION (C) OR FLOW-ADJUSTED CONCENTRATION (FAC) LOWESS LINE

CENSORING 

Increasing None 

85
Chattahoochee River, 

SR 369, Brown's Bridge, Ga. (location 2, Figure 16) Lake Sidney Lanier

10

1

0.1

0.01

10

1

0.1

0.01

10

1

0.1

0.01

Chattahoochee Riv(location 17)

Chattahoochee River,Gwinnett County Water Intake, Ga.(location 3)

Chattahoochee River,LaGrange Water Intake, Ga.(location 21)West Point Lake 

Chattahoochee River at Franklin, Ga.(location 20)inflow to West Point Lake

Chattahoochee River,Columbus Water Intake, Ga.(location 25)

Chattahoochee River,Seaboard Coastline Railroad, Omaha, Ga.(location 28)Walter F. George Reservoir

Chattahoochee River near (location 31)inflow to Lake Seminole

Chattahoochee River,upstream from Bartletts Fe(location 24)Lake Harding

TOTAL-PHOSPHORUS CONCENTRATION AS P, IN MILLIGRAMS PER LITER

Figure 39. Temporal variation in total-phosphorus concentrations for selected streams and reservoirs and 1980-90 tRiver, 1972–90 water years. (See table 15 for more information on trends.)

1970 1975 1980 1985 1990 1970 1975 198

1970 1975 1980 1985 1990 

C 

C

C

C

C

C, FAC

EXPLANATION

1980-90 TREND IN CONCENTRATION (C) OR FLOW-ADJUSTED CONCENTRATION (FAC) LOWESS LINE

CENSORING 

Increasing 

86
10

1

0.1

0.01

10

1

0.1

0.01

10

1

0.1

0.01

.

EXPLANAT

LOWESS LINE

CENSORING LIMIT

DISSOLVED-AMMONIA CONCENTRATION AS N, IN MILLIGRAMS PER LITER Increasing

None

Decreasing

Figure 40. Temporal variation in dissolved-ammonia concentrations for selected streams and reservoirs and 1980-90 tand Apalachicola Rivers, 1972–90 water years. (Locations 33, 35, and 37 are plotted with 4-log cycle scales. See table information on trends.)

1970 1975 1980 1985 1990

C,

C

FAC

C, FAC

C, FAC

1970 1975 1980 1985 1990

1970 1975 1980 

Flint River near Fayetteville, Ga.(location 33, Figure 16) Flint River above Griffin, Ga. (location 35) Flint River at Montezuma, Ga

(location 37)

Flint River near Vienna, Ga.(location 38)Inflow to Lake Blackshear

Flint River near Putney, Ga.(location 41)

Flint River below Bainbridge, (location 43)Inflow to Lake Seminole

Chipola River near Altha, Fla.(location 47)

Apalachicola River,Buoy 40, Mile 11A, Fla.(location 46)

100

C, . C FAC

1980-90 TREND IN C OR FLOW-ADJU (FAC)

87
10

1

0.1

0.01

10

1

0.1

0.01

10

1

0.1

0.01

DISSOLVED-NITRATE CONCENTRATION AS N, IN MILLIGRAMS PER LITER

Figure 41. Temporal variation in dissolved-nitrate concentrations for selected streams and reservoirs and 1980-90 trendand Apalachicola Rivers, 1972–90 water years. (See table 15 for more information on trends.)

1970 1975 1980 1985 1990 1970 1975 1980 1985 1990

1970 1975 1980 

C, FAC C, FAC

Flint River above Griffin, Ga.(location 35) Flint River at Montezuma, Ga. (location 37)

Flint River near Vienna, Ga.(location 38)Inflow to Lake Blackshear

Flint River near Putney, Ga.(location 41)

Flint River below Bainbridge, Ga(location 43)Inflow to Lake Seminole

Chipola River near Altha, Fla.(location 47)

Apalachicola River,Buoy 40, Mile 11A, Fla.(location 46)

Flint River near Fayetteville, Ga.(location 33, Figure 16)

. C, .

C

C, FAC

. C, . FAC

C, . FAC

.

EXPLANAT

LOWESS LINE

CENSORING LIMIT

Increasing

None

Decreasing

1980-90 TREND IN C OR FLOW-ADJUS (FAC)

88
1970 1975 1980 1985 1990 1970 1975 1980 1985 1990

10

1

0.1

0.01

10

1

0.1

0.01

10

1

0.1

0.01

TOTAL-PHOSPHORUS CONCENTRATION AS P, IN MILLIGRAMS PER LITER

C C, FAC .

. C, . FAC

Figure 42. Temporal variation in total-phosphorus concentrations for selected streams and reservoirs and 1980-90 trenand Apalachicola Rivers, 1972–90 water years. (See table 15 for more information on trends.)

1970 1975 1980 

C, FAC

C, FAC

Flint River above Griffin, Ga.(location 35) Flint River at Montezuma, Ga. (location 37)

Flint River near Vienna, Ga.(location 38)Inflow to Lake Blackshear

Flint River near Putney, Ga.(location 41)

Flint River below Bainbridge, G(location 43) Inflow to Lake Seminole

Chipola River near Altha, Fla.(location 47)

Apalachicola River,Buoy 40, Mile 11A, Fla.(location 46)

Flint River near Fayetteville, Ga.(location 33, Figure 16)

C 

.

EXPLANAT

LOWESS LINE

CENSORING LIMIT

Increasing

None

Decreasing

1980-90 TREND IN C OR FLOW-ADJUS (FAC)

89
90

decreasing trend in dissolved-ammonia concentrations and increasing trend in dissolved-nitrate 

concentrations downstream of Albany (Flint River at 

Putney, location 41; figs. 40, 41) are similar to 

patterns downstream of Atlanta (Chattahoochee River 

near Fairburn and at Franklin, locations 17 and 20; 

figs. 37, 38). Trends in nutrient concentrations in the 

Apalachicola and Chipola Rivers either were slight or 

not significant at the 90-percent confidence level 

(table 15, figs. 40–42).

Annual loads and mean annual yields

Annual loads were estimated for 1972–90 water 

years for total nitrogen, total-inorganic nitrogen, totalorganic nitrogen, dissolved ammonia, dissolved 

nitrate, total phosphorus, and dissolved 

orthophosphate at sites on the Apalachicola, 

Chattahoochee, and Flint Rivers, and at a few 

tributary sites where sufficient data were available 

(table 16, at end of report). Loads generally increase 

with increasing drainage area because of a positive 

relation between drainage area and discharge. Load 

estimates are not used when the standard error of the 

load estimate is greater than 30 percent of the load 

estimate for a given year. The period of record for 

load estimates is longer than the period of record for 

nutrient-concentration data when discharge data for 

one to three years are similar to discharge data for 

years with water-quality data and the standard error of 

the load estimates based on simulated nutrientconcentration data are less than 30 percent of the load 

estimates. Loads for Apalachicola River, Buoy 40 

(location 46), for 1972–76 are based on synthesizedflow data from a time lag of flow data collected at 

Apalachicola River near Blountstown (78 mi 

upstream from the mouth of the Apalachicola River) 

and at Chipola River near Altha (Marvin Franklin, 

U.S. Geological Survey, written commun., 1994). 

Loads determined at sites downstream of West Point 

Lake on the Chattahoochee River since 1975 show the 

effects of the reservoir, which began filling in October 

1974.

Annual load estimates were calculated using 

various relations among time (to compensate for longterm trends), logarithm of discharge, and sine and 

cosine of time (to compensate for seasonal 

variations). Instantaneous nutrient loads are calculated by multiplying the nutrient concentration by the 

stream discharge at the time of sample collection. 

Annual loads are more difficult to accurately estimate 

because concentration data are limited (often monthly 

or quarterly), and because nutrient concentrations are 

highly variable as a result of a wide variety of 

physical, chemical, and biological factors. For data 

sets without censored observations, the Minimum 

Variance Unbiased Estimator (Cohn and others, 1989; 

Gilroy and others, 1990) method was used to estimate 

annual loads, and for data sets with censored 

observations, the Adjusted Maximum Likelihood 

Estimator (Cohn, 1988) method was used. Accuracy 

of the constituent transport models and estimated 

loads depend on how much of the variance in nutrient 

concentrations can be explained by discharge and 

time, and how representative samples are of the range 

of hydrologic conditions at each site. Many factors 

that influence or control nutrient cycling (particularly 

for nitrogen) and transport were not accounted for in 

models used to estimate nutrient loads in this report. 

Concentration data collected during high-flow 

conditions are particularly important because the 

timing, amount, and distance of transport of many 

constituents is strongly influenced by high-flow 

conditions. Errors in individual estimates of nutrient 

load generally are less than differences: (1) among 

nutrient loads at each site among years with different 

hydrologic conditions (wet, normal, dry years); (2) 

among nutrient loads among sites along a flow system 

for a given period of time or hydrologic condition; 

and (3) between the amount of nutrients exported 

from a basin compared to estimated sources of 

nutrients. Load estimates are also useful in 

determining the proportion of nitrogen load in organic 

and inorganic form.

Estimated annual loads of dissolved ammonia, 

dissolved nitrate, and total phosphorus and mean 

annual discharge for eight surface-water sites are 

shown in figure 43 for 1972–90 water years. 

Estimated annual loads of dissolved nitrate tend to 

parallel year-to-year fluctuations in mean annual 

discharge more closely than dissolved ammonia or 

total phosphorus. An exception to this included a 

large increase in annual load of dissolved nitrate at the 

Chipola River (location 47). This increase may be the 

result of increases in irrigated agricultural land and 

fertilizer applications in the Chipola River watershed. 

The Floridan aquifer system underlies the Chipola 

River watershed, is karstic, and has relatively fast 

recharge rates and high transmissivities. These 

hydraulic characteristics may allow nutrients from 

land-surface sources to rapidly leach to the aquifer 

and discharge to the Chipola River. Another exception 

is Flint River above Griffin (location 35), which had 

significant decreases in concentrations and loads in 

dissolved nitrate and total phosphorus as a result of 

removal of several municipal wastewater-treatment 

discharges from the Upper Flint River in the early- to
0

600

200

400

0

300

100

200

1972 1990 1975 1980 1985

0

12,000

2,000

4,000

6,000

8,000

10,000

0

6,000

1,000

2,000

3,000

4,000

5,000

1972 1990 1975 1980 1985

0

12,000

2,000

4,000

6,000

8,000

10,000

0

6,000

1,000

2,000

3,000

4,000

5,000

1972 1990 1975 1980 1985

0

40,000

10,000

20,000

30,000

0

20,000

5,000

10,000

15,000

1972 1990 1975 1980 1985

0

3,000

1,000

2,000

0

1,500

500

1,000

1972 1990 1975 1980 1985

0

12,000

2,000

4,000

6,000

8,000

10,000

0

6,000

1,000

2,000

3,000

4,000

5,000

1972 1990 1975 1980 1985

0

12,000

2,000

4,000

6,000

8,000

10,000

0

6,000

1,000

2,000

3,000

4,000

5,000

1972 1990 1975 1980 1985

0

3,000

1,000

2,000

0

1,500

500

1,000

1972 1990 1975 1980 1985

Chattahoochee River, 

Gwinnett County Water 

Intake, Ga.

(location 3, Figure 16)

ANNUAL LOAD, IN TONS

MEAN ANNUAL DISCHARGE, IN CUBIC FEET PER SECOND

WATER YEAR WATER YEAR

EXPLANATION

Flint River above Griffin, Ga.

(location 35)

Flint River at

Montezuma, Ga.

(location 37)

Flint River near Putney, Ga.

(location 41)

Chattahoochee River near Fairburn, Ga.

(location 17)

Chattahoochee River,

Columbus Water Intake, Ga.

(location 25)

Apalachicola River,

Buoy 40, mile 11A

(location 46)

Figure 43. Annual loads of dissolved ammonia, dissolved nitrate, and total phosphorus and mean 

annual discharge for eight stream-sampling sites, Apalachicola-Chattahoochee-Flint River basin,

1972-90 water years.

Chipola River near Altha, Fla.

(location 47)

DISSOLVED AMMONIA DISSOLVED NITRATE TOTAL PHOSPHOROUS DISCHARGE

91
92

mid-1980’s. During the period 1972–80, Chattahoochee River near Fairburn (location 17; fig. 43) and 

Chattahoochee River at I-285 and near Whitesburg 

(locations 15 and 19, not shown in fig. 43) had larger 

estimated annual dissolved-ammonia loads than

dissolved-nitrate loads. Estimated dissolved-ammonia 

loads declined steadily in the river reach downstream 

of Atlanta from 1972–90 (location 17, fig. 43), in spite 

of population growth and increases in the volume of 

treated effluent discharged from WWTF during this 

same time period. Estimated ammonia loads, that 

were larger than nitrate loads in the 1970’s, are an 

indication of the relatively low level of treatment that 

municipal-wastewater effluent in the Metropolitan 

Atlanta area received during the 1970’s. The 

conversion from larger ammonia loads to larger 

nitrate loads in the 1980’s indicates the effectiveness 

of major improvements to WWTF in reducing 

ammonia loads, and subsequently reducing the threat 

of toxicity to fish by decreasing oxygen demand and 

ammonia toxicity of the effluent. The conversion also 

helps decrease the potential for eutrophication 

downstream of WWTF because dissolved nitrate in 

rivers is more readily denitrified (nitrogen gas 

released to the atmosphere) than dissolved ammonia.

Annual loads of total inorganic and organic 

nitrogen at mainstem sites are shown in figure 44 for 

1989–a year of moderate flow; and for 1990–a year 

that included a several-week period of extremely high 

flows on the Chattahoochee River. The mouths of the 

Chattahoochee and Flint Rivers join in Lake Seminole 

to form the headwaters of the Apalachicola River. To 

help visually compare values in a downstream 

direction, data from the Apalachicola River are shown 

with data from the Chattahoochee River and the Flint 

River. At 10 sites where organic-nitrogen load could 

be estimated, organic nitrogen ranged from 27 to 77 

percent of the total-nitrogen load in the ACF River 

basin. Because a large percent of total nitrogen is 

organic in form, future monitoring programs that 

intend to estimate total-nitrogen load should include 

organic nitrogen. Nitrogen loads in the Chattahoochee 

and Flint Rivers increased at a moderate rate 

downstream as drainage areas increased. Large 

increases in nitrogen loads occurred at sites in the 

Chattahoochee River downstream of Atlanta. In 1990, 

higher flows in the Chattahoochee and Apalachicola 

Rivers resulted in proportionately higher loads 

compared to loads in 1989.

Annual loads of total phosphorus at mainstem 

sites in 1989 and 1990 are shown on figure 45. 

Increases in phosphorus loads at sites downstream of 

Atlanta and Albany were proportionately larger than 

increases in nitrogen loads because municipal wastewater was the primary source of phosphorus in the 

rivers. A large decrease in phosphorus load occurred 

downstream of West Point Lake because much of the 

phosphorus was adsorbed onto sediments that were 

deposited in the reservoir. Proportionately more of the 

phosphorus load was deposited in West Point Lake in 

1989 than 1990 because higher flows in 1990 reduced 

residence time in the reservoir. Extreme high flows 

such as occurred in the Chattahoochee River in 1990 

cause greater turbulence in reservoirs which keeps 

more sediment in suspension and reduces the time 

available for settling of sediment and phosphorous 

uptake by aquatic organisms. Annual phosphorus 

loads were similar near the headwaters and the mouth 

of the Apalachicola River in 1989. In 1990, loads in 

the Apalachicola River were nearly three times 

greater than in 1989 and, similar to nitrogen loads, 

estimated phosphorus loads decreased downstream. 

However, because of the variance in the estimates, it 

can only be stated that the Apalachicola River system 

and its floodplain were probably a sink for 

phosphorus in 1990.

The floodplain ecosystem of the Apalachicola 

River either is a source or a sink for nutrients 

depending on the season, flow conditions, and 

location (Mattraw and Elder, 1984, p. C33–C37). 

Comparisons of ranges of annual load estimates 

(mean-annual load estimate for each year plus or 

minus the standard error of the estimate for that year) 

between sites can provide some indication if the 

stream reach between sites was a source or a sink for a 

constituent. Comparisons of ranges of annual load 

estimates for Apalachicola River at Chattahoochee 

(location 45) and Apalachicola River, Buoy 40, mile 

11a (location 46) indicate that the Apalachicola River 

and its floodplain were a source for total phosphorus 

for 17 years (1972–88) and could have been either a 

source or a sink (estimates of loads plus or minus the 

standard error of the estimate overlap) in 1989–90. 

Based on ranges of annual load estimates for 

dissolved nitrate, the Apalachicola River and its 

floodplain were a source for 7 years, a sink for 2 

years, and had an unknown role for 10 years. Ranges 

of estimated annual dissolved-ammonia loads at these 

two sites overlapped for all 19 years.

Estimated nitrogen and phosphorus loads flowing 

from the Apalachicola River into Apalachicola Bay 

were relatively small compared to nutrient sources 

estimated in this report to the ACF River basin from 

animal manure, fertilizer, atmospheric deposition, and 

municipal-wastewater effluent (fig. 46). Load 

estimates for 1990 water year for Apalachicola River,
550 500 400 300 200 

550 500 400 300 200 100 0 550 500 400 300 200 

550 500 400 300 200 100 0

DISTANCE, IN RIVER MILES ABOVE THE MOUTH OF THE APALACHICOLA RIVER

EXPLANATION

1989 CHATTAHOOCHEE RIVER

1989

CHATTAHOOCHEE RIV

1990

1990

APALACHICOLA RIVER APALACHICOLA RIVER

FLINT RIVER FLINT RIVER

Inorganic nitrogen Organic nitrogen Total nitrogen No organic nitrogen data 

NITROGEN LOAD, IN TONS

Figure 44. Nitrogen loads at selected sites along the Apalachicola, Chattahoochee, and Flint Rivers, 1989 and 1990 wat

30,00025,00020,00015,00010,000

5,000

0

32,000

30,00025,00020,00015,00010,000

5,000

0

32,000

30,00025,00020,00015,00010,000

5,000

0

32,000

30,00025,00020,00015,00010,000

5,000

0

32,000

1 3 4 6

7 1 3 4 6

7

15

17

15 19 22 25 

17 19 22 25 30 45 46 

32

33

34

35 

36 37 40 41 42 45 46 32

33

34

35 

36 37 40 41 

LOCATION (Figure 16)

Columbus

Lake Sidney Lanier

Lake Seminole

Walter F. George Reservoir

West Point Lake

Lake Sidney Lanier

Columbus

WltFGRi

West Point Lake

Atlanta

Atlanta

Lake Blackshear

Lake Worth

Albany

Lake Seminole

Atlanta

Lake Blackshear

Lake Worth

Albany

Atlanta

93
CHATTAHOOCHEE RIV

1989

Atlanta

550 500 400 300 200 100 0 0

2,500

500

1,0001,5002,000

Lake Blackshear

Lake Worth

Albany

Lake Seminole

Atlanta

Lake Blackshear

Lake Worth

Albany

FLINT RIVER FLINT RIVER

CHATTAHOOCHEE RIVER

550550

0

2,500

500

1,0001,5002,000

0

2,500

500

1,0001,5002,000

500 400 300 200 

0

2,500

500

1,0001,5002,000

550 500 400 300 200 100 0 500 400 300 200 

1990

1990

1989

APALACHICOLA RIVERAPALACHICOLA RIVER

Figure 45. Total-phosphorus loads at selected sites along the Apalachicola, Chattahoochee, and Flint Rivers, 1989 and 1

19 22 25 30 45 46

7

3 4 6 15

17

Columbus

Lake Sidney Lanier

Walter F. George Reservoir

West Point Lake

Atlanta

Lake Seminole

1

32

33

34

35 

36 37 40 41 42 45 46 32

33

34

35 

37 40 41 

Columbus

Lake Sidney Lanier

Walter FGeorge Reservoir

Atlanta

West Point Lake

1 3 6 15 19 22 25 

7 17

DISTANCE, IN RIVER MILES ABOVE THE MOUTH OF THE APALACHICOLA RIVER

PHOSPHORUS LOAD, IN TONS

LOCATION (Figure 16)

94
120,000

100,000

80,000

60,000

40,000

20,000

0

30,000 

25,000 

20,000 

15,000 

10,000 

5,000 

0

Poultry and livestock

Fertilizer

Atmospheric deposition

Apalachicola River, River Mile 11

Municipal wastewater

treatment facilities

Poultry and livestock

Fertilizer

Atmospheric deposition

Apalachicola River, River Mile 11

Municipal wastewater treatment facilities

Total

N

Total

N

Total

N

NO3

NO3

NH4

NH3

NH3

NH4

NH4

Organic

N

Organic

N

NO3

 

 NUTRIENT SOURCES

 

Nonpoint-source inputs

 Point-source loads

 NUTRIENT OUTPUT

 TOTAL NITROGEN

 DISSOLVED NITRATE

 AMMONIUM

 AMMONIA

 ORGANIC NITROGEN

NITROGEN, IN TONS TOTAL PHOSPHORUS, IN TONS

Figure 46. Nitrogen and total-phosphorus sources to and output from the ApalachicolaChattahoochee-Flint River basin, 1990. NO DATA 

EXPLANATION

95
96

Buoy 40, mile 11A (location 46) were 13 percent 

(30,400 tons) of estimated nitrogen sources and three 

percent (1,320 tons) of estimated phosphorus sources 

to the ACF River basin. Mean discharge for 1990 

water year near the mouth of the Apalachicola River 

was 15 percent higher than average discharge from 

1977–1990 (Meadows and others, 1991, p. 92). Much

of the year-to-year variation in estimates of nutrient 

loads flowing into Apalachicola Bay is controlled by 

year-to-year variation in quantity of water flowing 

into the bay. Load estimates (accounting for standard 

errors) for Apalachicola River, Buoy 40, mile 11A 

ranged from 9,180 to 33,900 tons/yr of nitrogen and 

from 660 to 3,500 tons/yr of total phosphorus for 

1974–90 water years. These estimates were calculated

with nutrient-concentration data from 1974–90 water 

years (river mile 11) and synthesized-flow data from 

1974–77 and actual-flow data for 1978–90 water years 

(river mile 20.6). By comparison, Mattraw and Elder 

(1984, p. C1 and C55) estimated loads of 24,000 tons 

of nitrogen and 1,900 tons of total phosphorus for the 

one-year period from June 3, 1979, to June 2, 1980, 

and Frick and others (1993, p. 39) estimated 18,900 

tons of nitrogen and 860 tons of total phosphorus for 

1990 calendar year.

Yields (load divided by drainage area) are a way 

to normalize load estimates and facilitate comparisons 

among watersheds of different sizes. Estimated 

mean-annual yields ranged from 0.72 to 2.9 tons/mi2

for total nitrogen, 0.27 to 2.0 tons/mi2 for totalinorganic nitrogen, 0.27 to 0.74 tons/mi2

 for totalorganic nitrogen, 0.02 to 1.1 tons/mi2 for dissolved 

ammonia, 0.22 to 1.2 tons/mi2

 for dissolved nitrate, 

0.05 to 0.75 tons/mi2

 for total phosphorus, and 0.02 to 

0.03 tons/mi2

 (range based on only three sites) for 

dissolved orthophosphate (table 16). Yields could not 

be calculated for dissolved-organic nitrogen. 

In unmodified watersheds, yields generally 

remain relatively constant as drainage area increases. 

Mean-annual yields of most nutrients increased in the 

Chattahoochee and Flint Rivers in and downstream of 

Atlanta. The Chattahoochee River downstream of 

Atlanta (locations 15, 17, or 19) had the highest 

mean-annual yields estimated in the ACF River basin 

for total nitrogen, total-inorganic nitrogen, dissolved 

ammonia, and total phosphorus, and the second 

highest mean-annual yield estimates in the basin for 

dissolved nitrate. Yields of total-inorganic nitrogen, 

dissolved ammonia, dissolved nitrate, and total phosphorus decreased substantially in the Chattahoochee 

River at the site downstream of West Point Lake 

(location 22) and continued to decrease downstream. 

This indicates that West Point Lake probably acts as a 

sink for these nutrient species. Yields of totalinorganic nitrogen, dissolved ammonia, dissolved 

nitrate, and total phosphorus decreased between sites 

upstream and downstream of all four reservoirs (Lake 

Sidney Lanier, locations 1 to 3; West Point Lake, 

locations 19 to 22; Lake Harding, locations 22 to 25; 

and Walter F. George Reservoir, locations 25 to 30) on 

the Chattahoochee River with available nutrient data. 

The only exception was that the yield of dissolved 

ammonia increased slightly downstream of Lake 

Sidney Lanier. For the time period 1972–90, nutrient 

yields in the Flint River were relatively high upstream 

of Griffin because of WWTF effluent discharged to 

the headwaters of the Flint River. Chipola River near 

Altha (location 47) had the highest estimated meanannual yields for total-organic nitrogen and dissolved 

nitrate. Relatively high yields of dissolved nitrate 

(1.2 tons/mi2) and low yields of dissolved ammonia 

(0.06 tons/mi2) and total phosphorus (0.07 tons/mi2) 

in the Chipola River suggests an agricultural nonpoint 

source of nutrient, rather than a point source, that 

probably enters the Chipola River as ground-water 

discharge rather than overland flow.

Nutrients in Ground Water

Nitrate is the nutrient of primary concern in 

ground water in most areas because elevated 

concentrations of nitrate in drinking-water supplies 

pose a possible health risk, and nitrate is the only 

major nutrient for which a MCL (10 mg/L as 

nitrogen) has been established by USEPA for drinking 

water. Data are more abundant for nitrate 

concentrations in ground water than for other nitrogen 

and phosphorus compounds. Natural sources of 

nitrate in ground water primarily include dissolution 

from nitrogen-bearing minerals in aquifer materials 

and leaching of nitrogen from natural soils. A partial 

list of anthropogenic sources of nitrate in ground 

water includes leaching of fertilizer and animal 

manure, infiltration of sewage from septic tanks, land 

application of treated effluent, and atmospheric 

deposition.
97

Dissolved ammonia has not been considered 

important in ground water because it is readily 

adsorbed and rapidly oxidized in aerobic 

environments. Dissolved ammonia can be produced in 

an aquifer by anoxic decomposition of organic 

material or by reduction of nitrate or can be derived 

directly from the surface application of nitrogen 

fertilizer in the form of anhydrous ammonia (Burkart 

and Kolpin, 1993, p. 651).

Within the ACF River basin, concentrations of 

dissolved nitrate in ground water (fig. 47) were higher 

and much more varied than in surface water (fig. 15). 

Concentrations of organic nitrogen, dissolved 

ammonia, and dissolved orthophosphate in ground 

water were very low. Nutrient data for springs are 

limited to 16 springs (fig. 47b).

10

1

0.10

0.01

Total nitrogen

Total inorganic nitrogen

Total organic

nitrogen

Dissolved ammonia

Dissolved nitrate

Dissolved

organic nitrogen

Total phosphorus

Dissolved

orthophosphate

Total nitrogen

Total inorganic nitrogen

Total organic

nitrogen

Dissolved ammonia

Dissolved nitrate

Dissolved

organic nitrogen

Total phosphorus

Dissolved

orthophosphate

Number of wells or springs 

 with nutrient analyses 

90

75

50

25

10

Censoring limit

Percentile

EXPLANATION

Figure 47. Distribution of nutrient concentrations in (A) wells and (B) springs by nutrient-constituent groups, 

Apalachicola-Chattahoochee-Flint River basin, 1972–90 water years.

53

38 53

23 63

185

32

53

58

3 3

3

4

15

1

CONCENTRATION, IN

MILLIGRAMS PER LITER

2 1

A B

MEDIAN NUTRIENT CONCENTRATION 

 OF INDIVIDUAL SPRINGS— All data are 

 plotted when the total number of springs

 sampled is less than or equal to 10. 

 Median concentrations may be the same 

 at two or more springs.
98

Nitrate concentrations

In a nationwide evaluation of the occurrence of 

nitrate in ground water based on more than 87,000 

wells, Madison and Brunett (1985, p. 95) defined the 

following four ranges of nitrate concentrations:

• less than 0.2 mg/L—assumed to represent 

natural background concentrations;

• 0.21 to 3.0 mg/L—transitional concentrations that may or may not represent 

human influence;

• 3.1 to 10 mg/L—probably indicates 

elevated concentrations resulting from 

human activities; and

• more than 10 mg/L—exceeds MCL for 

drinking-water supplies set by the 

USEPA.

Using the same ranges as Madison and Brunett 

(1985), the distribution of nitrate concentrations based 

on analyses from 185 wells and 15 springs in the ACF 

River basin for 1972–90 water years was:

• 70 wells (38 percent) and 9 springs 

(60 percent) with concentrations representative of natural background; 

• 94 wells (51 percent) and 5 springs

(33 percent) with concentrations that may 

or may not be influenced by humans; 

• 19 wells (10 percent) and 1 spring 

(6 percent) with concentrations that 

probably have elevated nitrate 

concentrations, and 

• 2 wells (1 percent) with median nitrate 

concentrations exceeding the MCL of 

10 mg/L.

The maximum concentration of dissolved nitrate 

measured within the ACF River basin was 36.9 mg/L 

in USGS test well 13, Albany, Ga., 178-ft deep in the 

Floridan aquifer system.

In a national review of over 200,000 nitrate 

analyses, Spalding and Exner (1993) stated that 

“aquifers in highly agricultural areas of the 

southeastern USA reportedly are not contaminated.” 

Some reasons for the lack of widespread nitrate contamination in Southeast, in spite of extensive fertilizer 

use on row crops (Kellogg and others, 1992), include 

vegetative uptake and denitrification in a warm, wet 

carbon-rich environment (Spalding and Exner, 1993). 

Forested riparian buffer strips, which are common in 

the Coastal Plain of the ACF River basin, are effective 

in reducing nutrients in streamflow (Lowrance and 

Pionke, 1989; Hubbard and Sheridan, 1989). 

Hubbard and others (1984) reported that nitrate concentrations beneath forested areas ranged from less 

than 0.1 to 1.1 mg/L in shallow ground water, 

compared with concentrations from less than 1 to 113 

mg/L beneath a center pivot site using sprinklerapplied fertilizer and intense multiple cropping systems. 

Buffer strips between fields and within agricultural fields are becoming more common in the 

study area, and may act as filters for nutrients and 

sediment and may be another reason for relatively low 

nitrate concentrations in ground water near agricultural areas of the ACF River basin. This is in contrast 

to regions of the United States such as the midwest 

where large areas of well-drained soils are in irrigated 

cropland areas and as many as 29 percent of samples 

exceed 3 mg/L of nitrate and 6 percent exceed 

10 mg/L of nitrate (Burkart and Kolpin, 1993; 

Spalding and Exner, 1993; Hamilton and Helsel, 

1995).

There were too few nitrate analyses in ground 

water from 1972–90 in the northern part of the ACF 

River basin, where poultry production was highest, to 

determine if nitrate concentrations were elevated near 

intensive poultry production and litter application 

areas. In a recent study in the White and Mossy Creek 

watersheds (north of Lake Sidney Lanier) by Peck 

and Garrett (1994), six out of 24 wells sampled in 

1992–93 had nitrate concentrations higher than 

3 mg/L and two wells exceeded the USEPA drinkingwater standard of 10 mg/L nitrate.

Three studies to determine the distribution and 

occurrence of nitrate concentrations in shallow 

ground water in Georgia were conducted between 

1989 and 1994. Although the nutrient data are not 

included in this report; the studies deserve to be 

mentioned because of the large number and thorough 

spatial distribution of samples collected. From 1990 

through 1994, the Georgia Geologic Survey (GGS) 

sampled about 4,800 domestic drinking-water wells 

that were less than 250 feet deep to evaluate nonpoint 

sources of nitrate in the State’s ground water. Nitrate 

concentrations exceeded the MCL of 10 mg/L in less 

than 2 percent of 2,588 domestic wells sampled in 

south Georgia (Stuart and others, 1995; Georgia 

Department of Natural Resources, 1992). In another 

study, the University of Georgia Cooperative Extension Service determined nitrate concentrations in 
99

water samples collected from 1989 through 1993 

from 3,419 domestic wells. The MCL for nitrate was 

exceeded in 3.8 percent of wells having depths less 

than 100 feet and 0.9 percent of wells having depths 

more than 100 feet (Tyson and others, 1995). In 1994, 

the University of Georgia Cooperative Extension Service reported that the MCL for nitrate was exceeded 

in samples from 5.1 percent of 823 wells located on 

farms in counties with large livestock and poultry 

production. The MCL for nitrate was exceeded in 7.5 

percent of the subset of those wells used specifically 

for livestock and poultry (Tyson and others, 1995).

Nutrient distributions by aquifer and well depth

Ground-water sampling sites for nutrients within 

the ACF River basin appear to be reasonably well 

distributed areally and among aquifers (fig. 48); 

however, several gaps in available data are apparent 

in figure 49. For example, measurements are not 

available from 1972–90 for dissolved ammonia or 

total phosphorus in the crystalline-rock aquifers, 

which means the occurrence and distribution of these 

nutrients are unknown for the northern one-third of 

the study area. Sample sizes smaller than 10 are too 

small to compare statistically. Sample sizes larger 

than 30 are preferred, because larger sample sizes are 

more likely to be representative of the population of 

interest. The Floridan aquifer system was the only 

aquifer having more than 10-sampling sites with 

dissolved-ammonia or total-phosphorus concentration 

data within the ACF River basin. Kruskal-Wallis test 

(followed by Mann-Whiney tests) for dissolved 

nitrate, indicate that dissolved-nitrate concentrations 

were significantly higher in the Floridan aquifer 

system and the crystalline-rock aquifers than in the 

Providence aquifer (fig. 49; Inman and Conover, 

1983, p. 418–19). Probable reasons for higher nitrate 

concentrations in water from the Floridan aquifer 

system include: 

• a prevalence of row-crop agricultural 

land-use overlying the Floridan aquifer 

system, 

• samples collected from a high percentage 

of shallow wells in the Upper Floridan 

aquifer, and 

• relatively high aquifer transmissivities 

within the Upper Floridan aquifer. 

Probable reasons for higher nitrate concentrations 

in water from the crystalline-rock aquifers include: 

• a prevalence of poultry agricultural landuse overlying the crystalline-rock 

aquifers, and 

• wells often are large-diameter shallowbored wells in the regolith which may be 

more susceptible to contamination than 

drilled wells. 

There are no statistically significant differences 

among nitrate concentrations among other aquifers 

(fig. 49). The lack of significant differences may be 

the result of relatively small sample sizes rather than 

actual lack of differences.

Some studies have reported inverse relations 

between well depths in shallow aquifers (generally for 

well depths less than 50 to 100 ft) and nitrate 

concentrations (Madison and Brunett, 1985, p. 95; 

Burkart and Kolpin, 1993, p. 654; Hamilton and 

others, 1989, p. 47). Because most nitrate sources 

either are at land surface or in the soil column, 

shallow aquifers probably are more susceptible to 

nitrate contamination than deeper aquifers (Madison 

and Brunett, 1985, p. 97). Older water, deep in an 

aquifer, is less likely to be affected by human 

activities. Nitrate concentrations in shallow ground 

water (less than 100 feet deep) could not be compared 

with deeper ground water in the ACF because, with 

the exception of the Floridan aquifer system, very few 

shallow wells had nitrate-concentration data available 

for 1972–90 water years (fig. 48). The relation 

between depth of water below land surface and nitrate 

concentration could not be tested, because many 

water-quality data analyses from 1972–90 in the ACF 

River basin (particularly analyses stored in STORET) 

do not include ground-water-level data.
30

31

33

34

84

o

o

o

85o

32o

o

o Crystalline-rock aquifer

EXPLANATION

SPRING

WELLS

Depth 100 feet or less

Depth greater than 100 feet

Depth unknown

AQUIFER OUTCROP AREA

30

31

33

34

84

o

o

o

85o

32o

o

o Providence aquifer

30

31

33

34

84

o

o

o

85o

32o

o

o

Clayton aquifer

30

31

33

34

84

o

o

o

85o

32o

o

o

Claiborne

aquifer

Figure 48. Location of ground-water-sampling sites with nutrient data, by aquifer and well depth, 

Apalachicola-Chattahoochee-Flint River basin, 1972-90 water years.

Base from U.S. Geological Survey digital files

100
30

31

33

34

84

o

o

o

85o

32o

o

o

30

31

33

34

84

o

o

o

85 o

32o

o

o

Figure 48. Location of ground-water-sampling sites with nutrient data, by aquifer and well depth, 

Apalachicola-Chattahoochee-Flint River basin, 1972-90 water years—Continued.

Base from U.S. Geological Survey digital files

Floridan aquifer system Surficial aquifer system

EXPLANATION

SPRING

WELLS

Depth 100 feet or less

Depth greater than 

 100 feet

Depth unknown

AQUIFER OUTCROP AREA

101

Nutrient distributions by water-use category

Distributions of dissolved ammonia, dissolved 

nitrate, and total phosphorus by water-use category are 

shown in figure 50. Dissolved-nitrate concentrations in 

public-supply wells were significantly lower than in 

domestic and unused wells. Public-supply wells tend to 

be deeper and are initially drilled in locations expected 

to have low nitrate concentrations. Most public-supply 

wells that have high nitrate concentrations either are 

abandoned or their water is mixed with water from 

another source to reduce nitrate concentrations to meet 

USEPA drinking-water standards. Domestic wells tend 

to be shallower, may have less stringent well 

construction and sanitary seal requirements, and are 

often drilled in close proximity to sources of nitrate 

contamination such as septic fields, agricultural fields, 

or animal-feeding areas. The water-use category 

“unused” was assigned to water-quality-monitoring 

wells, test-wells (often drilled to test hydraulic 

properties of an aquifer), and abandoned wells. Wells 

used for other water-use categories (irrigation, 

commercial, industrial, or recreation) were not 

compared because of sample sizes less than 10.
10

1

0.1

0.01

10

1

0.1

0.01

100

10

1

0.1

0.01

Crystalline-rock aquifer

Providence aquifer

Clayton aquifer

Claiborne

aquifer

Floridan aquifer system

Surficial aquifer

system

Dissolved nitrate

Total phosphorus

Dissolved ammonia

 CONCENTRATION, IN MILLIGRAMS PER LITER

Maximum contaminant level

Figure 49. Distribution by aquifer of dissolved-ammonia, dissolved-nitrate, and total-phosphorus

concentrations in wells, Apalachicola-Chattahoochee-Flint River basin, 1972–90 water years. 

Number of wells with 

 nutrient analyses

Censoring limit

90

75

50

25

10

Percentile

EXPLANATION

96

32

29

8

11 96

6

2

2

42

5

10

2

2

48

MEDIAN NUTRIENT CONCEN-

 TRATION OF INDIVIDUAL 

 WELLS— All data are plotted 

 when the total number of wells 

 sampled is less than or equal 

 to 10. Median concentrations 

 may be the same at two or 

 more wells

102
10

1

0.1

0.01

10

1

0.1

0.01

100

10

1

0.1

0.01

Dissolved nitrate

Total phosphorus

Dissolved ammonia

 CONCENTRATION, IN MILLIGRAMS PER LITER

Figure 50. Distribution by water-use category of dissolved-ammonia, dissolved-nitrate, and total-phosphorus

concentrations in wells, Apalachicola-Chattahoochee-Flint River basin, 1972–90 water years. 

2

2

27

1

24

76

20

3

2 10

4

61

24 8

2

1

2

15

Maximum contaminant level

Public supply

Domestic

Irrigation

Commercial

Industrial

Recreational

Unused

Number of wells with 

 nutrient analyses

Censoring limit

90

75

50

25

10

Percentile

EXPLANATION

61

MEDIAN NUTRIENT CONCEN-

 TRATION OF INDIVIDUAL 

 WELLS— All data are plotted 

 when the total number of wells 

 sampled is less than or equal 

 to 10. Median concentrations 

 may be the same at two or 

 more wells

103
104

SUMMARY

In 1991, the U.S. Geological Survey (USGS) began 

full-scale implementation of the National Water-Quality 

Assessment (NAWQA) program. One of the initial 

tasks of the NAWQA program is to compile and 

evaluate existing data from individual study units. This 

report estimates nutrient sources to the ACF River basin 

and describes the presence, distribution, and transport 

of nutrients in surface and ground waters based on 

available and accessible nutrient data collected during 

the period 1972–90 water years. Where possible, 

variations in nutrient water quality are related to 

hydrologic, environmental, and anthropogenic factors.

Nutrient sources to the ACF River basin from 

municipal wastewater-treatment facilities (WWTF), 

animal manure, fertilizer, and atmospheric deposition 

for 1990 were estimated and compared with nutrient 

outputs. Estimates of nutrient input to the ACF River 

basin were not made for natural sources and for the 

following anthropogenic sources: industrialwastewater effluent; storm drains; sanitary and 

combined sewer overflows; and runoff from 

agricultural, urban, and suburban areas. Point-source 

loads from WWTF effluent were about 2,500 tons of 

nitrogen and 1,100 tons of phosphorus. Unlike pointsource loads, an unknown percentage of nonpointsource inputs (manure, fertilizer, and atmospheric 

deposition) enter the hydrologic system. Manure 

generated by chickens, cows, and pigs in the ACF River 

basin contained about 120,000 tons of nitrogen and 

28,000 tons of phosphorus. Poultry production was 

concentrated in a 5-county area in the headwaters of the 

Chattahoochee River and accounted for 89 percent of 

the nutrient input from manure. About 82,000 tons of 

nitrogen and 20,000 tons of phosphorus were applied as 

fertilizer to lands in the ACF River basin. The lower 

part of the basin, predominantly the row-crop 

agricultural areas of the Middle and Lower Flint River 

subbasins, received the greatest input of nitrogen and 

phosphorus from commercial fertilizer. Information on 

nitrogen and phosphorus inputs from fertilizer applied 

to urban and suburban areas are unavailable for most of 

the ACF River basin; however, conservative estimates 

would increase the estimates of total nutrient inputs 

from fertilizer to the ACF River basin by about 10 

percent. Atmospheric deposition of nitrogen was about 

24,000 tons in 1990 calendar year. Nutrient outflow 

into Apalachicola Bay from Apalachicola River was 

about 13 percent of estimated nitrogen sources and 

about three percent of estimated total phosphorus 

sources for 1990 in the ACF River basin.

Changes in nutrient concentrations, loads, and 

yields in river reaches from upstream to downstream of 

metropolitan areas provide indications of the combined 

affects of large point sources and urban nonpoint 

sources. The metropolitan areas of Atlanta, Ga.; 

Columbus, Ga. and Phenix City, Ala.; and Albany, Ga.; 

contained all municipal discharges larger than 10 

Mgal/d in 1990 within the ACF River basin. These 

large municipal discharges contributed to significant 

increases in concentrations of total-inorganic nitrogen, 

dissolved ammonia, dissolved nitrate, and total 

phosphorus from upstream to downstream of the 

metropolitan areas of Atlanta, Columbus and Phenix 

City, and Albany. There were also significant increases 

in concentrations of total nitrogen, total-organic 

nitrogen, and dissolved orthophosphate from upstream 

to downstream of Atlanta and of total nitrogen and 

dissolved orthophosphate from upstream to 

downstream of Albany. Concentrations of dissolved 

ammonia, dissolved nitrate, and total phosphorus at 

Chattahoochee River near Fairburn (downstream of 

Atlanta) decrease as flow increases indicating that point 

sources account for much of the load. The same 

relation occurs between dissolved nitrate and discharge 

at Flint River near Putney (downstream from Albany); 

however, the cause could be from the dilution of 

baseflow and(or) the dilution of point-source loads. In 

addition to increases in concentrations, large increases 

in nitrogen and phosphorus loads and yields occurred 

from upstream to downstream of Atlanta, Columbus 

and Phenix City, and Albany. Increases in phosphorus 

loads from upstream to downstream of urban centers 

were proportionately larger than increases in nitrogen 

loads because municipal wastewater was the primary 

source of phosphorus in the rivers from 1972–90. The 

Chattahoochee River downstream of Atlanta had the 

highest mean-annual yields estimated in the ACF River 

basin for total nitrogen, total-inorganic nitrogen, 

dissolved ammonia, and total phosphorus, and the 

second highest mean-annual yield estimates in the basin 

for dissolved nitrate.
105

Many improvements to the water quality of the 

Chattahoochee and Flint Rivers in the 1980’s and early 

1990’s can be directly attributed to improvements in 

wastewater-treatment facilities, legislation directed at 

decreasing point-source loads of phosphorus, and 

changes in wastewater-treatment outfall locations. 

Three examples are:

• From 1972–80, the Chattahoochee River 

downstream of Atlanta had annual 

dissolved-ammonia loads larger than 

dissolved-nitrate loads because of the 

relatively low level of treatment of 

municipal-wastewater effluent in the 

Metropolitan Atlanta area during the 

1970’s. The reversal to larger nitrate loads 

than ammonia loads in the 1980’s is an 

indication of positive effects from major 

improvements made to WWTFs in the 

1980’s. Decreasing trends in dissolvedammonia concentration and increasing 

trends in dissolved-nitrate concentration 

in the Chattahoochee and Flint Rivers at 

sites downstream of Atlanta and Albany 

were the result of improved wastewater 

treatment at WWTF in these urban areas. 

The conversion from larger ammonia 

loads to larger nitrate loads in the 1980’s 

indicates the effectiveness of major 

improvements to WWTF in reducing 

ammonia loads, and subsequently 

reducing the threat of toxicity to fish by 

decreasing oxygen demand and ammonia 

toxicity of the effluent. The conversion 

also helps decrease the potential for eutrophication downstream of WWTF because 

dissolved nitrate in rivers is more readily 

denitrified than dissolved ammonia.

• Increasing trends in total-phosphorus 

concentrations throughout most of the 

Chattahoochee River are an accurate 

representation of data for the period 1980–

90. However, legislated restrictions on the 

use of phosphate detergents and 

improvements of WWTF beginning in the 

late 1980’s resulted in substantial 

reductions in concentrations of 

phosphorus in wastewater influent and 

effluent in the 1990’s. Point-source loads 

of phosphorus from the 13 major WWTF 

that discharge into the Chattahoochee 

River between Buford Dam and West 

Point Lake decreased from a high of 1,670 

tons in 1988 to 298 tons in 1993. Totalphosphorus loads in the Chattahoochee 

River upstream of Metropolitan Atlanta 

continued to increase from 47 tons in 

1988 to 200 tons in 1993, because of 

increases in nonpoint-source inputs. 

Although volume of effluent discharged 

increased, total-phosphorus loads in the 

Chattahoochee River downstream from 

Atlanta decreased from 1,190 tons in 1988 

to 550 tons in 1993, primarily because of 

large decreases in point-source loads.

• The Upper Flint River (downstream of 

Atlanta) and Long Cane Creek 

(downstream of effluent discharged from 

LaGrange, Ga.) had high concentrations 

and yields of total-inorganic nitrogen, 

dissolved ammonia, dissolved nitrate, and 

total phosphorus during the period 1972–

90, because of municipal effluent 

discharged into relatively small streams 

with low waste-assimilation capacities. 

Long Cane Creek also had strong negative 

relations between dissolved-ammonia and 

total-phosphorus concentrations and

discharge during 1972–90. As a result of 

removal of municipal-wastewater outfalls 

from the Upper Flint River basin in the 

early- to mid-1980’s, all significant trends 

in nutrient concentrations in the Upper 

Flint decreased for 1980–90 and the rates 

of decreases were larger in the Upper Flint 

than rates of change for any other surfacewater-quality site within the study area for 

the 1980–90 period. The discharge 

location of effluent from the city of 

LaGrange was moved from Long Cane 

Creek to the Chattahoochee River in 

1993. Concentrations of nutrients most 

commonly in effluent were about an 

order-of-magnitude less in 1994 in the 

Upper Flint River and in Long Cane 

Creek than concentrations shown for 

1972–90 water years.

Reservoirs affect transport of nutrients because of 

uptake by phytoplankton and aquatic plants, 

denitrification, and accumulation of phosphorus 

associated with sediment in reservoirs. Totalphosphorus concentrations significantly decreased from 

sampling sites in and downstream of Lake Sidney 

Lanier, West Point Lake, Lake Harding, and the Flint 

River arm of Lake Seminole. Four nutrient species 

significantly decreased downstream of Walter F. George 

Reservoir and six nutrient species significantly 

decreased downstream of the Flint River arm of Lake 

Seminole. Total-inorganic nitrogen and dissolved nitrate 

in Lake Sidney Lanier were the only constituents in any 

reservoir in the study area that had a significant increase 
106

in nutrient concentrations from a reservoir sampling site 

to a downstream sampling site during 1972–90. Yields 

of total-inorganic nitrogen, dissolved ammonia, 

dissolved nitrate, and total phosphorus decreased 

between sampling sites upstream and downstream of all 

four reservoirs on the Chattahoochee River with 

available nutrient data. The only exception was the 

yield of dissolved ammonia increased slightly from 

upstream to downstream of Lake Sidney Lanier. In 

general, nitrogen loads and yields decreased 

downstream of West Point Lake. Large decreases in 

phosphorus loads occurred downstream of West Point 

Lake, because much of the phosphorus is associated 

with sediments that are deposited in the reservoir. 

Much of the nutrient load in the Chattahoochee River 

downstream of Atlanta is utilized by algae or settles out 

primarily in West Point Lake, and to a lesser extent, in 

Lake Harding and Walter F. George Reservoir. In 

general, the Flint River arm of Lake Seminole had 

significantly higher concentrations of nutrients than the 

Chattahoochee River arm of Lake Seminole, which may 

be the result of the large percentage of the Middle and 

Lower Chattahoochee River in backwater from 

reservoirs, the absence of reservoirs on the Flint River 

downstream of Albany until Lake Seminole, and 

nonpoint-source inputs of nutrients from intensively 

farmed areas in the Lower Flint River basin. 

 Seasonal variations in nutrient concentrations in 

the Chattahoochee River are strongly influenced by the 

13 reservoirs on the river, particularly from West Point 

Lake to Lake Seminole. Dissolved-nitrogen concentrations are generally lower in the warm, summer months 

near the inflow of West Point Lake to Lake Seminole 

for ammonia and near the center of West Point Lake to 

Lake Seminole for nitrate. Total-phosphorus concentrations also seem to be lower in the summer and early fall 

in the Middle and Lower Chattahoochee River, 

although the pattern is not as pronounced as for dissolved ammonia and dissolved nitrate. Summer 

decreases in concentrations of nutrients in reservoirs, 

and stream sites directly affected by reservoirs, are 

related to the seasonality of phytoplankton production 

in reservoirs. In contrast to the Chattahoochee 

River, seasonal patterns in nutrient concentrations in 

the Flint, Chipola, and Apalachicola Rivers either are 

not present or are less apparent.

In addition to changes in nutrients in surface-water 

as a result of urban point and nonpoint sources, 

municipal-wastewater effluent, reservoirs, and seasonal 

variations, several miscellaneous observations about 

nutrients in surface waters of the ACF include:

• No noticeable changes in nutrient 

concentrations occurred in mainstem 

rivers in the ACF River basin downstream of confluences of eight tributary 

streams with sufficient available nutrientconcentration data. In general, tributaries 

in the ACF River basin have small 

discharges relative to the discharge of the 

mainstem rivers they flow into.

• Concerns about accelerated eutrophication were warranted throughout much 

of the ACF River basin based on totalphosphorus concentrations from 1972–90.

Concerns about toxicity to fish were 

intermittently warranted based on 

dissolved-ammonia concentrations downstream of wastewater-treatment outfalls 

for the Metropolitan Atlanta area in the 

Chattahoochee and Flint Rivers and 

downstream of the wastewater-treatment 

outfall for LaGrange in Long Cane Creek.

• In river reaches downstream of all major 

point-source loads from Atlanta, 

Columbus, and Phenix City, and Albany 

metropolitan areas, total-phosphorus and 

dissolved-ammonia concentrations significantly decreased from sampling sites 

near WWTFs to sampling sites further 

downstream. Significant decreases in 

total-phosphorus concentrations were 

probably the result of biological uptake, 

decomposition, and settling out of 

phosphorus associated with suspended 

sediment. Significant decreases in 

dissolved-ammonia and increases in 

dissolved-nitrate concentrations in these 

river reaches downstream of Atlanta and 

Albany occurred because of nitrification 

of ammonia to nitrate.

• Compared to other surface-water sampling 

sites within the ACF River basin, Chipola 

River near Altha, Fla. had moderate-tohigh dissolved-nitrate concentrations and 

the highest yields estimated in the basin 

for dissolved nitrate. Chipola River near 

Altha had decreasing relations between 

dissolved nitrate and discharge, which 

often are indicative of a nonpoint source 

of nitrate. Estimated loads of dissolved 

nitrate in the Chipola River increased 

fairly steadily from about 500 tons/yr in 
107

1972 to about 1,500 tons/yr in 1990, 

unlike most other load estimates which 

more closely paralleled changes in flow 

conditions from year to year. Large 

increases in estimates of mean-annual 

load of dissolved nitrate to the Chipola 

River are probably the result of elevated 

dissolved-nitrate concentrations in 

ground-water discharge (baseflow) from 

increased irrigated agriculture and 

fertilizer applications in the Chipola River 

watershed.

Analyses of nutrients in ground water within the 

ACF River basin for 1972–90 water years were 

restricted because of limited available data. A cursory 

description of distribution of nutrient concentrations in 

wells and springs; and for wells, differences in 

dissolved-nitrate concentrations by aquifer, by well 

depth, and by water-use category are presented. The 

distribution of nitrate concentrations for 1972–90 water 

years include 38 percent of wells and 60 percent of 

springs with concentrations representative of natural 

background (less than 0.2 mg/L); 51 percent of wells 

and 33 percent of springs with concentrations that may 

or may not be influenced by humans (0.21 to 3.0 mg/L); 

10 percent of wells and 6 percent of springs with 

concentrations that probably have elevated nitrate 

concentrations (3.1 to 10 mg/L), and 1 percent of wells 

with median nitrate concentrations exceeding the 

USEPA maximum contaminant level of 10 mg/L. 

Dissolved-nitrate concentrations in wells used for public 

supply were significantly lower than in wells used for 

domestic use and unused wells. Dissolved-nitrate 

concentrations were significantly lower in the 

Providence aquifer than in the Floridan aquifer system 

and the crystalline-rock aquifers. Statistically significant 

differences in nitrate concentrations were not identified 

among other aquifers possibly because of relatively 

small sample sizes rather than actual lack of differences. 

Nitrate concentrations in ground water less than 100 feet 

deep could not be compared with deeper ground water 

because, with the exception of the Floridan aquifer 

system, very few shallow wells had nitrateconcentration data available for 1972–90 water years.

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112

Table 16. Mean annual loads1/ and yields for nutrients for selected surface-water sampling sites, by nutrient constituent group2/, Apalachi

River basin, 1972–90 water years

[mg/L, milligrams per liter; Stream station name sources: F, Florida Department of Environmental Regulation; G, Georgia Environmental Protection Division; U, U.S. Geological Survey

Location 

number 

(figure 16)

Hydrologic 

unit code Stream station name

Period of 

record for 

nutrient load 

estimates

Number of nutrient observations

Mean annual 

load

 (tons)

Range of annual loa

 (tons) 

Less than 

censoring limit

Greater than or 

equal to censoring 

limit

(water years in 

parentheses)

Total nitrogen (0.12 mg/L = censoring limit)

6 03130001 Chattahoochee River - Cobb County Water Intake, Ga.G 5/1972–90 0 72 1,290 880–2,800

(1981; 1990)

17 03130002 Chattahoochee River near Fairburn, Ga.U 5/1972–90 0 152 6,010 4,950–9,060

(1981; 1990)

30 03130003 Chattahoochee River near Columbia, Ala.U 1983–90 0 41 8,960 5,610–12,400

(1988; 1984)

35 03130005 Flint River above Griffin, Ga.U 5/1974–90 0 148 335 75.3–889

(1988; 1975)

37 03130006 Flint River at Montezuma, Ga.U 5/1972–90 0 47 2,080 772–4,170

(1988; 1975)

41 03130008 Flint River near Putney, Ga.U 5/1972–90 0 68 4,430 2,740–6,580

(1988; 1975)

42 03130008 Flint River at Newton, Ga.U 5/1981–90 0 47 5,750 1,980–8,920

(1981; 1984)

45 03130011 Apalachicola River at Chattahoochee, Fla.U 5/1972–90 0 136 17,200 9,150–28,900

(1981; 1990)

47 03130012 Chipola River near Altha, Fla.U 5/1972–90 0 114 1,510 903–2,020

(1981; 1983, 84)

46 03130011 Apalachicola River, Buoy 40, mile 11A, Fla.F 6/1974–90 0 63 20,400 9,820–30,400

(1981; 1990)

Total-inorganic nitrogen (0.04 mg/L = censoring limit)

1 03130001 Chattahoochee River near Cornelia, Ga.U 1972–90 1 93 212 102–500

(1981; 1990)

3 03130001 Chattahoochee River - Gwinnett County Water Intake, 

Ga.G

5/1972–90 1 154 612 402–1,040

(1982; 1990)

4 03130001 Chattahoochee River - DeKalb County Water Intake, Ga.G 5/1972–90 0 165 661 407–1,120

(1981; 1990)

5 03130001 Big Creek - Roswell Water Intake, Ga.G 5,8/1972–89 0 117 106 37.2–404

(1981; 1984)

6 03130001 Chattahoochee River - Cobb County Water Intake, Ga.G 5/1972–90 0 185 827 621–1,530

(1981; 1990)

7 03130001 Chattahoochee River - Atlanta Water Intake, Ga.G 1972–90 0 204 1,040 669–2,060

(1981; 1990)
113

12 03130001 Peachtree Creek at Atlanta, Ga.U 5/1972–90 0 191 87.6 44.0–13

(1981; 19

15 03130002 Chattahoochee River at I-285, at Atlanta, Ga.U 1981–90 0 124 2,920 1,780–3,5

(1981; 19

16 03130002 Sweetwater Creek near Austell, Ga.U 8/1972–89 1 170 135 44.7–22

(1988; 19

17 03130002 Chattahoochee River near Fairburn, Ga.U 5/1972–90 0 258 4,140 3,530–6,2

(1972; 19

19 03130002 Chattahoochee River near Whitesburg, Ga.U 5/1972–90 0 327 4,090 3,320–6,6

(1981; 19

22 03130002 Chattahoochee River at West Point, Ga.U 9/1972–90 0 204 2,810 1,490–5,2

(1988; 19

25 03130002 Chattahoochee River - Columbus Water Intake, Ga.G 9/1972–90 1 211 3,340 1,860–6,5

(1986; 19

30 03130003 Chattahoochee River near Columbia, Ala.U 5/1979–89 1 35 4,610 1,710–8,7

(1988; 19

32 03130004 Flint River near Jonesboro, Ga.U 1985–90 0 71 38.4 12.4–69

(1985; 19

33 03130005 Flint River near Fayetteville, Ga.U 1985–90 0 69 45.1 16.5–77

(1985; 19

34 03130005 Flint River near Inman, Ga.U 1985–90 0 69 82.2 50.6–12

(1985; 19

35 03130005 Flint River above Griffin, Ga.U 5/1972–90 0 228 148 42.1–25

(1988; 19

36 03130005 Flint River near Culloden, Ga.U 1972–79, 

1990

0 57 492 329–88

(1972; 19

37 03130006 Flint River at Montezuma, Ga.U 5/1972–90 0 154 772 526–1,0

(1981; 19

40 03130008 Flint River at Albany, Ga.U 1972–90 0 71 2,320 1,420–3,3

(1981; 19

41 03130008 Flint River near Putney, Ga.U 5/1972–90 0 198 2,960 1,850–4,8

(1988; 19

Table 16. Mean annual loads1/ and yields for nutrients for selected surface-water sampling sites, by nutrient constituent group2/, Apa

River basin, 1972 – 90 water years—Continued

[mg/L, milligrams per liter; Stream station name sources: F, Florida Department of Environmental Regulation; G, Georgia Environmental Protection Division; U, U.S. Geological S

Location 

number 

(figure 16)

Hydrologic 

unit code Stream station name

Period of 

record for 

nutrient load 

estimates

Number of nutrient observations

Mean annual 

load

 (tons)

Range of annu

 (tons) 

Less than 

censoring limit

Greater than or 

equal to censoring 

limit

(water yea

parenthes
114

42 03130008 Flint River at Newton, Ga.U 5/1972–90 0 52 3,420 2,070–4,

(1981; 19

45 03130011 Apalachicola River at Chattahoochee, Fla.U 5/1972–90 0 153 8,730 3,880–15

(1981; 19

47 03130012 Chipola River near Altha, Fla.U 5/1972–90 0 134 1,000 539–1,5

(1972; 19

46 03130011 Apalachicola River, Buoy 40, mile 11A, Fla.F 6/1974–90 0 83 8,830 4,440–12

(1981; 19

Total-organic nitrogen (0.1 mg/L = censoring limit)

6 03130001 Chattahoochee River - Cobb County Water Intake, Ga.G 1979–89 25 43 559 259–75

(1981; 19

17 03130002 Chattahoochee River near Fairburn, Ga.U 5/1973–90 15 136 1,400 1,400–2,

(1981; 19

30 03130003 Chattahoochee River near Columbia, Ala.U 1985–89 0 30 4,690 3,890–6,

(1988; 19

35 03130005 Flint River above Griffin, Ga.U 1976–90 8 134 142 31.0–36

(1986; 19

37 03130006 Flint River at Montezuma, Ga.U 1972–88 10 37 1,360 243–3,2

(1988; 19

41 03130008 Flint River near Putney, Ga.U 8/1974–89 8 64 1,440 829–2,0

(1981; 19

42 03130008 Flint River at Newton, Ga.U 1983–89 0 43 3,010 1,740–4,

(1989; 19

45 03130011 Apalachicola River at Chattahoochee, Fla.U 5/1972–90 1 135 8,430 4,760–14

(1986; 19

47 03130012 Chipola River near Altha, Fla.U 5,8/1972–86 14 84 577 248–93

(1981; 19

46 03130011 Apalachicola River, Buoy 40, mile 11A, Fla.F 6/1974–90 4 55 11,600 5,380–19

(1981; 19

Table 16. Mean annual loads1/ and yields for nutrients for selected surface-water sampling sites, by nutrient constituent group2/, Apa

River basin, 1972 – 90 water years—Continued

[mg/L, milligrams per liter; Stream station name sources: F, Florida Department of Environmental Regulation; G, Georgia Environmental Protection Division; U, U.S. Geological S

Location 

number 

(figure 16)

Hydrologic 

unit code Stream station name

Period of 

record for 

nutrient load 

estimates

Number of nutrient observations

Mean annual 

load

 (tons)

Range of ann

 (tons) 

Less than 

censoring limit

Greater than or 

equal to censoring 

limit

(water yea

parenthes
115

Dissolved ammonia (0.02 mg/L = censoring limit)

1 03130001 Chattahoochee River near Cornelia, Ga.U 1972–90 26 68 39.3 13.2–125

(1972; 1990)

3 03130001 Chattahoochee River - Gwinnett County Water Intake, 

Ga.G

5/1972–90 24 138 142 110–230

(1981,82; 1990)

4 03130001 Chattahoochee River - DeKalb County Water Intake, Ga.G 5/1972–90 27 147 151 106–250

(1981; 1990)

5 03130001 Big Creek - Roswell Water Intake, Ga.G 5,8/1973–89 1 57 11.2 4.7–22.3

(1986; 1973)

6 03130001 Chattahoochee River - Cobb County Water Intake, Ga.G 5/1972–90 18 179 205 162–363

(1981; 1990)

7 03130001 Chattahoochee River - Atlanta Water Intake, Ga.G 1972v90 32 174 180 103–416

(1981; 1990)

12 03130001 Peachtree Creek at Atlanta, Ga.U 5/1972–90 3 188 20.3 10.5–35.1

(1981; 1990)

15 03130002 Chattahoochee River at I-285, at Atlanta, Ga.U 1981–90 0 124 1,740 1,280–2,140

(1981; 1982)

16 03130002 Sweetwater Creek near Austell, Ga.U 8/1973–89 14 121 38.6 11.6–79.5

(1986; 1976)

17 03130002 Chattahoochee River near Fairburn, Ga.U 5/1972–90 1 256 2,070 1,830–2,320

(1989; 1973)

19 03130002 Chattahoochee River near Whitesburg, Ga.U 5/1972–90 0 329 1,320 960–1,750

(1989; 1973)

22 03130002 Chattahoochee River at West Point, Ga.U 9/1972–90 7 197 608 365–1,260

(1988; 1990)

25 03130002 Chattahoochee River - Columbus Water Intake, Ga.G 9/1972–90 25 187 647 313–1,700

(1986; 1990)

30 03130003 Chattahoochee River near Columbia, Ala.U 5/1981–89 3 39 822 312–1,590

(1988; 1983)

32 03130004 Flint River near Jonesboro, Ga.U 1985–90 0 71 15.1 5.2–26.1

(1985; 1990)

33 03130005 Flint River near Fayetteville, Ga.U 1985–90 1 68 13.8 7.5–21.0

(1985; 1987)

Table 16. Mean annual loads1/ and yields for nutrients for selected surface-water sampling sites, by nutrient constituent group2/, Apalach

River basin, 1972 – 90 water years—Continued

[mg/L, milligrams per liter; Stream station name sources: F, Florida Department of Environmental Regulation; G, Georgia Environmental Protection Division; U, U.S. Geological Surve

Location 

number 

(figure 16)

Hydrologic 

unit code Stream station name

Period of 

record for 

nutrient load 

estimates

Number of nutrient observations

Mean annual 

load

 (tons)

Range of annual lo

 (tons) 

Less than 

censoring limit

Greater than or 

equal to censoring 

limit

(water years in 

parentheses)
116

34 03130005 Flint River near Inman, Ga.U 8/1985–89 0 47 18.5 10.0–27.5

(1985; 1989)

35 03130005 Flint River above Griffin, Ga.U 5/1972–90 19 209 21.6 12.7–29.5

(1988; 1975)

36 03130005 Flint River near Culloden, Ga.U 1972–79 38 17 37.9 23.9–47.0

(1972; 1975)

37 03130006 Flint River at Montezuma, Ga.U 5/1974–90 38 108 143 46.5–270

(1974; 1990)

40 03130008 Flint River at Albany, Ga.U 8/1972–89 14 52 581 284–1,050

(1981; 1984)

41 03130008 Flint River near Putney, Ga.U 5/1972–90 4 198 737 333–1,410

(1988; 1973)

42 03130008 Flint River at Newton, Ga.U 5/1974–90 5 45 497 247–923

(1988; 1975)

45 03130011 Apalachicola River at Chattahoochee, Fla.U 5/1972–90 22 131 1,110 538–2,020

(1988; 1975)

47 03130012 Chipola River near Altha, Fla.U 5/1972–90 33 101 48.5 23.4–66.1

(1985; 1983)

46 03130011 Apalachicola River, Buoy 40, mile 11A, Fla.F 6/1974–90 28 56 1,070 534–1,760

(1988; 1975)

Dissolved nitrate (0.01 mg/L = censoring limit)

1 03130001 Chattahoochee River near Cornelia, Ga.U 1972–90 0 100 172 83.3–375

(1981; 1990)

3 03130001 Chattahoochee River - Gwinnett County Water Intake, 

Ga.G

5/1972–90 0 165 470 285–812

(1988; 1990)

4 03130001 Chattahoochee River - DeKalb County Water Intake, Ga.G 5/1972–90 0 176 510 292–869

(1988; 1990)

5 03130001 Big Creek - Roswell Water Intake, Ga.G 5,8/1972–89 0 121 74.0 30.8–248

(1972; 1984)

6 03130001 Chattahoochee River - Cobb County Water Intake, Ga.G 5/1972–90 0 196 622 459–1,160

(1981; 1990)

7 03130001 Chattahoochee River - Atlanta Water Intake, Ga.G 1972–90 0 213 860 566–1,650

(1981; 1990)

Table 16. Mean annual loads1/ and yields for nutrients for selected surface-water sampling sites, by nutrient constituent group2/, Apalac

River basin, 1972 – 90 water years—Continued

[mg/L, milligrams per liter; Stream station name sources: F, Florida Department of Environmental Regulation; G, Georgia Environmental Protection Division; U, U.S. Geological Surv

Location 

number 

(figure 16)

Hydrologic 

unit code Stream station name

Period of 

record for 

nutrient load 

estimates

Number of nutrient observations

Mean annual 

load

 (tons)

Range of annual 

 (tons) 

Less than 

censoring limit

Greater than or 

equal to censoring 

limit

(water years i

parentheses)
117

12 03130001 Peachtree Creek at Atlanta, Ga.U 5/1972–90 0 192 67.3 33.5–100

(1981; 198

15 03130002 Chattahoochee River at I-285, at Atlanta, Ga.U 1981–90 0 125 1,180 498–2,00

(1981; 199

16 03130002 Sweetwater Creek near Austell, Ga.U 1972–90 0 184 84.8 32.0–130

(1988; 198

17 03130002 Chattahoochee River near Fairburn, Ga.U 5/1972–90 0 258 2,080 1,240–4,27

(1972; 199

19 03130002 Chattahoochee River near Whitesburg, Ga.U 5/1972–90 0 326 2,770 1,600–5,57

(1972; 199

22 03130002 Chattahoochee River at West Point, Ga.U 9/1972–90 0 199 2,200 1,120–3,95

(1988; 199

25 03130002 Chattahoochee River - Columbus Water Intake, Ga.G 9/1972–90 0 217 2,690 1,540–4,82

(1986; 199

30 03130003 Chattahoochee River near Columbia, Ala.U 5/1980–90 0 37 3,460 1,400–6,3

(1988; 198

32 03130004 Flint River near Jonesboro, Ga.U 1985–90 0 74 23.3 7.2–43.3

(1985; 199

33 03130005 Flint River near Fayetteville, Ga.U 1985–90 0 75 31.3 9.0–60.6

(1985; 199

34 03130005 Flint River near Inman, Ga.U 1985–90 0 73 57.2 40.7–93

(1985; 198

35 03130005 Flint River above Griffin, Ga.U 5/1972–90 0 236 126 29.3–230

(1988; 197

36 03130005 Flint River near Culloden, Ga.U 1972–79,

1990

0 59 445 305–761

(1972; 199

37 03130006 Flint River at Montezuma, Ga.U 5/1972–90 0 168 640 405–869

(1988; 197

40 03130008 Flint River at Albany, Ga.U 1972–90 0 76 1,700 1,140–2,26

(1981; 197

41 03130008 Flint River near Putney, Ga.U 5/1972–90 0 205 2,220 1,440–3,46

(1981; 197

Table 16. Mean annual loads1/ and yields for nutrients for selected surface-water sampling sites, by nutrient constituent group2/, Apala

River basin, 1972 – 90 water years—Continued

[mg/L, milligrams per liter; Stream station name sources: F, Florida Department of Environmental Regulation; G, Georgia Environmental Protection Division; U, U.S. Geological Su

Location 

number 

(figure 16)

Hydrologic 

unit code Stream station name

Period of 

record for 

nutrient load 

estimates

Number of nutrient observations

Mean annual 

load

 (tons)

Range of annua

 (tons) 

Less than 

censoring limit

Greater than or 

equal to censoring 

limit

(water years 

parenthese
118

42 03130008 Flint River at Newton, Ga.U 5/1972–90 0 53 2,900 1,820–3,8

(1981; 198

45 03130011 Apalachicola River at Chattahoochee, Fla.U 5/1972–90 0 153 7,620 3,280–14,4

(1981; 199

47 03130012 Chipola River near Altha, Fla.U 5/1972–90 0 134 953 500–1,48

(1972; 199

46 03130011 Apalachicola River, Buoy 40, mile 11A, Fla.F 6/1974–90 0 98 7,760 3,900–10,

(1981; 198

Total phosphorous (0.02 mg/L = censoring limit)

1 03130001 Chattahoochee River near Cornelia, Ga.U 1972–90 24 76 39.7 13.3–99

(1981; 199

3 03130001 Chattahoochee River - Gwinnett County Water Intake, 

Ga.G

1975–90 104 64 62.2 21.2–23

(1982; 199

4 03130001 Chattahoochee River - DeKalb County Water Intake, Ga.G 5/1972–89 104 72 69.5 38.6–11

(1981; 198

5 03130001 Big Creek - Roswell Water Intake, Ga.G 5,8/1973–89 3 77 15.9 4.6–28.

(1986; 197

6 03130001 Chattahoochee River - Cobb County Water Intake, Ga.G 5/1972–90 32 185 169 131–314

(1981; 199

7 03130001 Chattahoochee River - Atlanta Water Intake, Ga.G 1972–90 12 204 202 96.6–58

(1981; 199

12 03130001 Peachtree Creek at Atlanta, Ga.U 5/1972–90 1 191 25.9 9.9–46.4

(1981; 199

15 03130002 Chattahoochee River at I-285, at Atlanta, Ga.U 1981–90 0 125 809 513–97

(1981; 199

16 03130002 Sweetwater Creek near Austell, Ga.U 1972–90 20 169 41.9 7.4–111

(1986; 197

17 03130002 Chattahoochee River near Fairburn, Ga.U 5/1972–90 0 260 1,540 1,260–1,9

(1986; 199

19 03130002 Chattahoochee River near Whitesburg, Ga.U 5/1972–90 0 328 1,380 1,090–1,9

(1981; 199

22 03130002 Chattahoochee River at West Point, Ga.U 9/1972–90 15 188 477 146–1,24

(1981; 197

Table 16. Mean annual loads1/ and yields for nutrients for selected surface-water sampling sites, by nutrient constituent group2/, Apal

River basin, 1972 – 90 water years—Continued

[mg/L, milligrams per liter; Stream station name sources: F, Florida Department of Environmental Regulation; G, Georgia Environmental Protection Division; U, U.S. Geological S

Location 

number 

(figure 16)

Hydrologic 

unit code Stream station name

Period of 

record for 

nutrient load 

estimates

Number of nutrient observations

Mean annual 

load

 (tons)

Range of annu

 (tons) 

Less than 

censoring limit

Greater than or 

equal to censoring 

limit

(water year

parenthes
119

25 03130002 Chattahoochee River - Columbus Water Intake, Ga.G 9/1972–90 14 206 474 161–1,29

(1986; 19

30 03130003 Chattahoochee River near Columbia, Ala.U 5/1978–90 7 41 440 203–75

(1988; 19

32 03130004 Flint River near Jonesboro, Ga.U 1985–90 1 73 8.2 3.1–13.

(1985; 19

33 03130005 Flint River near Fayetteville, Ga.U 1985–90 0 75 12.8 6.0–18.

(1985; 19

34 03130005 Flint River near Inman, Ga.U 1985–90 0 75 45.6 27.4–74

(1985; 19

35 03130005 Flint River above Griffin, Ga.U 5/1972–90 0 239 61.1 18.6–11

(1988; 19

36 03130005 Flint River near Culloden, Ga.U 1972–79 1 56 176 107–27

(1972; 19

37 03130006 Flint River at Montezuma, Ga.U 5/1972–90 8 160 267 149–49

(1988; 19

40 03130008 Flint River at Albany, Ga.U 1972–90 6 71 541 201–1,07

(1988; 19

41 03130008 Flint River near Putney, Ga.U 5/1972–90 1 208 540 331–92

(1988; 19

42 03130008 Flint River at Newton, Ga.U 5/1972–90 2 52 473 291–66

(1981; 19

45 03130011 Apalachicola River at Chattahoochee, Fla.U 5/1972–90 4 149 1,140 456–2,1

(1988; 19

47 03130012 Chipola River near Altha, Fla.U 5/1972–90 12 120 52.6 22.2–75

(1985; 19

46 03130011 Apalachicola River, Buoy 40, mile 11A, Fla.F 6/1974–90 18 83 1,590 634–3,07

(1988; 19

Dissolved orthophosphate (0.02 mg/L = censoring limit)

30 03130003 Chattahoochee River near Columbia, Ala.U 1983–90 42 6 11/ 11/ 42 03130008 Flint River at Newton, Ga.U 5/1981–90 13 36 191 149–24

(1988; 1983

Table 16. Mean annual loads1/ and yields for nutrients for selected surface-water sampling sites, by nutrient constituent group2/, Apal

River basin, 1972 – 90 water years—Continued

[mg/L, milligrams per liter; Stream station name sources: F, Florida Department of Environmental Regulation; G, Georgia Environmental Protection Division; U, U.S. Geological S

Location 

number 

(figure 16)

Hydrologic 

unit code Stream station name

Period of 

record for 

nutrient load 

estimates

Number of nutrient observations

Mean annual 

load

 (tons)

Range of annu

 (tons) 

Less than 

censoring limit

Greater than or 

equal to censoring 

limit

(water year

parenthes
120

45 03130011 Apalachicola River at Chattahoochee, Fla.U 5/1972–90 85 20 358 126–733

(1988; 1973)

47 03130012 Chipola River near Altha, Fla.U 1975–90 52 31 25.9 12.9–37.6

(1985; 1983)

1/ Annual loads were only included for years where the variance in the estimate was less than or equal to 30 percent.2/ Data were not available to calculate loads for dissolved-organic nitrogen at any sites within the Apalachicola–Chattahoochee–Flint River basin.3/ S dard error S dard deviation tan

Sample size

tan = -----------------------------------------------------

σ

n

= ------

4/ Mean annual yield = mean annual load ÷ drainage area. 5/ The period of record for load estimates is longer than the period of record for nutrient-concentration data when discharge data for one to three years 

years with water-quality data and the standard error of the load estimates based on simulated nutrient-concentration data are less than 30 percent o

6/ Load estimates for the Apalachicola River, Buoy 40, mile 11A (31010022) for 1974 to 1977 water years are based on synthesized flow data from a t

the Apalachicola River near Blountstown (02358700) and the Chipola River near Altha (02359000) (Marvin Franklin, U.S. Geological Survey, or

7/

S dard error tan dissolved ammonia ( )2 S dard error tan dissolved nitrate ( )2 + S dard error total inorganic nitrogen tan = ·

8/ Load estimates are not used for one or more years with nutrient-concentration data, because the standard error of the load estimates are greater than 9/ Storage in West Point Lake began October 16, 1974, and the reservoir reached maximum power pool June 10, 1975. Load estimates for 1972–74 at 

Point and the Chattahoochee River - Columbus Water Intake are representative of pre-reservoir conditions.

10/

S dard error tan total nitrogen ( )2 S dard errortotal inorganic nitrogen ( ) tan 2 + S dard error total organic nitrogen tan = ·

11/ Annual loads could not be estimated, because less than 20 percent of concentration data were greater than or equal to the censoring limit (Baier, G.

Geological Survey, written commun., 1993).

Table 16. Mean annual loads1/ and yields for nutrients for selected surface-water sampling sites, by nutrient constituent group2/, Apalach

River basin, 1972 – 90 water years—Continued

[mg/L, milligrams per liter; Stream station name sources: F, Florida Department of Environmental Regulation; G, Georgia Environmental Protection Division; U, U.S. Geological Surv

Location 

number 

(figure 16)

Hydrologic 

unit code Stream station name

Period of 

record for 

nutrient load 

estimates

Number of nutrient observations

Mean annual 

load

 (tons)

Range of annual l

 (tons) 

Less than 

censoring limit

Greater than or 

equal to censoring 

limit

(water years in 

parentheses)

Frick, E.A., Buell, G.R., and Hopkins, E.H.—NUTRIENT SOURCES AND ANALYSIS OF NUTRIENT WATER-QUALITY DATA, 


APALACHICOLA-CHATTAHOOCHEE-FLINT RIVER BASIN, GEORGIA, ALABAMA, AND FLORIDA, 1972-90—


U.S. Geological Survey WRIR 96-4101