U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2005–5271

Prepared in cooperation with the Upper Cape Fear River Basin Association

Suspended Sediment and Nutrients in the 

Upper Cape Fear River Basin, North Carolina, 

2002–04, with an Analysis of Temporal Changes, 

1976–2004
Cover.  Deep River spillway upstream from the U.S. highway 1 bridge in Chatham County, North Carolina (photograph by 

Ryan B. Rasmussen, U.S. Geological Survey).
Suspended Sediment and Nutrients in 

the Upper Cape Fear River Basin, North 

Carolina, 2002–04, with an Analysis of 

Temporal Changes, 1976–2004

By Timothy B. Spruill, Phillip S. Jen, and Ryan B. Rasmussen

Prepared in cooperation with the Upper Cape Fear River Basin Association

Scientific Investigations Report 2005–5271

U.S. Department of the Interior

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

Gale A. Norton, Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

U.S. Geological Survey, Reston, Virginia: 2006

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Suggested citation:

Spruill, T.B., Jen, P.S., and Rasmussen, R.B., 2006, Suspended sediment and nutrients in the upper Cape Fear River 

basin, North Carolina, 2002–04, with an analysis of temporal changes, 1976–2004: U.S. Geological Survey Scientific 

Investigations Report 2005–5271, 40 p.
iii

Contents

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

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

Purpose and Scope ..............................................................................................................................2

Study Area..............................................................................................................................................2

Acknowledgments................................................................................................................................5

Methods...........................................................................................................................................................5

Streamflow.............................................................................................................................................5

Water-Quality Data...............................................................................................................................5

Load-Estimation Techniques for Data Collected during 2002–04..................................................6

Load-Estimation Techniques for Historical Data.............................................................................7

Analysis of Temporal Changes ...........................................................................................................7

Streamflow, Suspended Sediment, and Nutrient Concentrations and Loads in the Upper 

Cape Fear River Basin, 2002–04.....................................................................................................8

Nutrient and Suspended-Sediment Concentrations.......................................................................9

Nutrient and Suspended-Sediment Loads .....................................................................................13

Annual Loads..............................................................................................................................13

Seasonal Loads..........................................................................................................................14

Historical Changes in Streamflow, Suspended-Sediment, and Nutrient Concentrations 

and Loads, 1976–2004 ....................................................................................................................16

Streamflow in the Haw River near Bynum .....................................................................................17 

Suspended Sediment in the Haw River near Bynum....................................................................17

Total Phosphorus in the Haw River near Bynum...........................................................................21

Total Nitrogen in the Haw River near Bynum.................................................................................22

Streamflow in the Deep River at Moncure.....................................................................................24

Suspended Sediment in the Deep River at Moncure ...................................................................24

Total Phosphorus in the Deep River at Moncure...........................................................................26

Total Nitrogen in the Deep River at Moncure ................................................................................26

Summary and Conclusions.........................................................................................................................26

References....................................................................................................................................................27

Appendixes ...................................................................................................................................................31

Figures

1. Locations of sampling sites in the Haw River and Deep River subbasins of the 

upper Cape Fear River basin, North Carolina, 2002–04 ..........................................................3

2. Box plots of streamflow in the (A) Haw River near Bynum and (B) Deep River at 

Moncure, North Carolina, for water years 2002–04................................................................9

3. Water types for the (A) Haw River near Bynum and (B) Deep River at Moncure, 

North Carolina, 2002–04.............................................................................................................10

4. Box plots of (A) total phosphorus, (B) total nitrogen, and (C) suspended-sediment 

concentrations in the Haw River near Bynum and the Deep River at Moncure, 

North Carolina, 2002–04.............................................................................................................11
iv

5. Seasonal concentrations of (A) suspended sediment, (B) orthophosphate, and 

(C) total nitrogen in the Haw River near Bynum and the Deep River at Moncure, 

North Carolina, 2002–04.............................................................................................................12

6. Seasonal loads of suspended sediment, total phosphorus, and total nitrogen 

in the Haw River near Bynum and the Deep River at Moncure, North Carolina , 

for water years 2003 and 2004 ..................................................................................................16

7. Box plots of annual streamflow in the Haw River near Bynum, North Carolina, 

1976–2004 .....................................................................................................................................17

8. Relation of (A) suspended-sediment data collected by the U.S. Geological 

Survey and (B) total suspended-solids data collected by the North Carolina 

Division of Water Quality to streamflow at the Haw River near Bynum, 

North Carolina, 1981–2004.........................................................................................................18

9. Box plots of (A) suspended-sediment concentrations for 1976–85 and 2002–04 

from the U.S. Geological Survey, and (B) total suspended-solids concentrations 

for 1981–91 and 1992–2004 from the North Carolina Division of Water Quality 

at the Haw River near Bynum, North Carolina.......................................................................19

10. Box plots of suspended-sediment concentrations at four different streamflow 

ranges for (A) 1976–85 and (B) 2002–04 in the Haw River near Bynum, 

North Carolina .............................................................................................................................19

11. Total phosphorus data from (A) the North Carolina Division of Water Quality and 

(B) the U.S. Geological Survey for the Haw River near Bynum, North Carolina, 

1980–2004, and trends indicated by LOWESS smooth lines ................................................21

12. Box plots of instantaneous phosphorus loads for 1981–85 and 2002–04 

at the Haw River near Bynum, North Carolina.......................................................................22

13. Total nitrogen concentrations from U.S. Geological Survey and North Carolina 

Division of Water Quality databases for the Haw River near Bynum, 

North Carolina, 1981–2003.........................................................................................................23

14. Box plots of annual streamflow in the Deep River at Moncure, North Carolina, 

1976–2004 .....................................................................................................................................25

Tables

1. Characteristics of (A) land use and (B) population and wastewater discharges 

in the Haw River and Deep River subbasins of North Carolina ............................................4

2. Analytical methods and reporting levels for nutrients and suspended sediment.............5

3. Analytical methods and reporting levels for dissolved major ions and selected 

trace elements ..............................................................................................................................6

4. List of regression models included in LOADEST computations............................................6

5. Selected streamflow statistics from the Haw River near Bynum and the Deep 

River at Moncure, North Carolina..............................................................................................8

6. Statistical summary of nutrient and suspended-sediment concentrations in the 

Haw and Deep Rivers, North Carolina, 2002–04 ....................................................................10

7. Nutrient and sediment loads and yields in the Haw and Deep Rivers, 

North Carolina, for calendar years 2002 and 2003 ................................................................13

8. Seasonal loads of nutrients and suspended sediment in the Haw River 

near Bynum and the Deep River at Moncure, North Carolina, during 

September 2002–August 2004...................................................................................................15
v

9. Annual suspended-sediment loads for calendar year 1976–2003 streamflows 

in the Haw River near Bynum, North Carolina, for two calibration periods, 

1976–89 and 2002–04 ..................................................................................................................20

10. Annual phosphorus loads for calendar year 1976–2003 streamflows in the Haw 

River near Bynum, North Carolina, for two calibration periods, 1976–89 

and 2002–04 .................................................................................................................................22

11. Annual total nitrogen loads for calendar year 1976–2003 streamflows in the 

Haw River near Bynum, North Carolina, for two calibration periods, 1981–85 

and 2002–04 .................................................................................................................................24

12. Annual suspended-sediment loads for calendar year 1976–2003 streamflows 

in the Deep River at Moncure, North Carolina, for two calibration periods, 

1976–83 and 2002–04 ..................................................................................................................26

Appendixes

Appendix 1. Nutrient and suspended-sediment concentrations in water samples 

from the Haw River near Bynum, North Carolina.........................................................33

Appendix 2. Nutrient and suspended-sediment concentrations in water samples 

from the Deep River at Moncure, North Carolina ........................................................35

Appendix 3. Selected major ions and trace element concentrations in water samples 

from (A) the Haw River near Bynum and (B) the Deep River at Moncure, 

North Carolina ....................................................................................................................37

Appendix 4. Equations used in load calculations for suspended sediment, total nitrogen, 

and phosphorus in (A) the Haw River near Bynum and (B) the Deep River 

at Moncure, North Carolina .............................................................................................39

Appendix 5. Planted crop acreage in counties in the upper Cape Fear River basin, 

1980–2004 ............................................................................................................................40
vi

Conversion Factors, Datum, and Acronyms

Multiply By To obtain

Length

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2) 2.590 square kilometer (km2)

Flow rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

million gallons per day (Mgal/d) 0.04381 cubic meter per second (m3/s)

ton per day (ton/d) 0.9072 megagram per day (Mg/d)

ton per year per square mile

[(ton/yr)/mi2]

0.3503 megagram per year per square

kilometer [(Mg/yr)/km2]

Water temperature was recorded in degrees Celsius (°C), which may be converted to degrees 

Fahrenheit (°F) as follows:

°F = (1.8 × °C) + 32

Specific conductance was measured in microsiemens per centimeter at 25 degrees 

Celsius (μS/cm at 25 °C).

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

or micrograms per liter (μg/L).

Horizontal coordinate information (latitude and longitude) is referenced to the North American 

Datum of 1983 (NAD 83). 

Acronyms

AIC	 Akaike information criterion

AMLE	 adjusted maximum likelihood estimator

ASF	 automated segmented-flow spectrophotometry

DCP	 data-collection platform

EROS	 Earth Resources Observation and Science

EWI	 equal-width increment

LAD	 least absolute deviation

LT	 Landsat thematic (map data)

MLE	 maximum likelihood estimator

MRLC	 Multi-Resolution Land Characteristics

N	 nitrogen

NC	 North Carolina

NCDWQ	 North Carolina Division of Water Quality

NO2 + NO3	 nitrite plus nitrate

NPDES	 National Pollutant Discharge Elimination System

NRI	 National Resource Inventory

NWIS	 National Water Information System

NWQL	 National Water Quality Laboratory

P	 phosphorus

UCFRBA	 Upper Cape Fear River Basin Association

USDA	 U.S. Department of Agriculture

USEPA	 U.S. Environmental Protection Agency

USGS	 U.S. Geological Survey
Abstract

An investigation of suspended sediment and nutrients 

was conducted in the Haw River near Bynum and in the Deep 

River at Moncure, North Carolina, to characterize water 

quality based on data collected weekly or biweekly between 

August 2002 and August 2004. Samples were collected five 

times per year for selected major ions and trace elements to 

help in characterizing the water quality at these sampling sites. 

Sediment and nutrient data collected from 1976 to 2004 also 

were analyzed to evaluate whether loads and concentrations 

changed significantly over this period. 

The water chemistry in the Haw and Deep Rivers is of 

mixed ionic composition, although the water chemistry in the 

Haw River is more variable. Water types in both rivers generally shifted from calcium and bicarbonate in the winter and 

spring months and during high flows to sodium and chloride 

during low flows in the summer. Sediment and nutrient loads 

were estimated for calendar years 2002 and 2003 using the 

nutrient and suspended-sediment concentration data collected between 2002 and 2004 for calibration of regression 

load models. Sediment and nutrient loads generally were 

greater in 2003, an unusually wet year, than in 2002. Annual 

constituent yields generally were higher in the Deep River 

with the exception of dissolved nitrate and nitrite. Phosphorus 

loads and concentrations were significantly higher in the 

Deep River as a result of substantial continuous-discharge 

sources of phosphorus, particularly near High Point, North 

Carolina. More stringent wastewater-treatment requirements 

in the Haw River primarily are responsible for much lower 

phosphorus concentrations and loads compared with those in 

the Deep River. Seasonal loads were evaluated at both sites 

for the period September 2002 through August 2004. Primary 

transport of nutrients and sediment occurred during spring 

2003 and winter 2004.

Historical flow and water-quality data previously 

collected at both sites by the U.S. Geological Survey and 

the North Carolina Division of Water Quality were used to 

evaluate historical changes through time and to compare 

information from the two datasets. Historical water-quality 

changes between 1976 and 2004 were greatest in the Haw 

River near Bynum, which had a statistically significant (p is 

less than 0.05) decrease in sediment, total nitrogen, and total 

phosphorus concentrations and loads. Decreases in cultivated 

land, improved land-management practices, and improved 

wastewater-treatment processes since the 1980s are primary 

reasons for the observed improvement in water quality in the 

Haw River. 

Because sampling was limited for nutrients (16 samples) 

and sediment (25 samples) in the Deep River, changes in 

concentrations between the early 1980s and 2002–04 were not 

statistically detectable (p is greater than 0.05) for suspended 

sediment, total nitrogen, or total phosphorus. Data from the 

North Carolina Division of Water Quality also indicated 

no change between 1992 and 2004. Calculated sediment 

loads, however, using the load-streamflow regression models 

calibrated for two separate periods, 1976–83 and 2002–04, 

indicate that sediment loads may be lower for 2002–04 compared with those in the early 1980s. Nutrient concentrations 

have remained relatively unchanged since the 1980s.

Introduction

The Upper Cape Fear River Basin Association 

(UCFRBA) in North Carolina established a 44-station waterquality sampling network in 2000 to support analyses of 

water quality in the Haw and Deep River basins and to serve 

as a basis for providing recommendations to local, State, and 

Federal authorities regarding maintenance and improvement 

of water quality and water resources in the upper Cape Fear 

River basin. The monitoring network was established under an 

agreement with the North Carolina Division of Water Quality 

(NCDWQ) and supersedes the NCDWQ in-stream monitoring 

requirements for point-source discharge facilities that participate in the UCFRBA monitoring program. 

Suspended Sediment and Nutrients in the Upper Cape Fear 

River Basin, North Carolina, 2002–04, with an Analysis of 

Temporal Changes, 1976–2004

By Timothy B. Spruill, Phillip S. Jen, and Ryan B. Rasmussen
To supplement these data, current information was 

needed on stream discharge and water quality at selected sites 

in the basin that are not directly influenced by point sources. 

Of particular importance were water-quality data for the 

Haw River above Jordan Lake and the Deep River before its 

confluence with the Haw River to form the Cape Fear River 

to document water-quality conditions in the upper part of the 

basin with respect to nutrients and sediment and excluding 

the effects of Jordan Lake. Such data, combined with data 

collected by the Lower Cape Fear River Program and Middle 

Cape Fear River Basin Association, will provide waterresource managers with a regional perspective on water quality 

in the Cape Fear River basin. In addition, data collected during 

the past 30 years from the upper Cape Fear River basin by the 

U.S. Geological Survey (USGS) and the NCDWQ are valuable 

in assessing changes in water quality in response to land use 

and other environmental and climatic factors.

The USGS, in cooperation with the UCFRBA, began a 

study in 2002 to collect and evaluate current water-quality 

data over a range of flows in the Deep and Haw Rivers in 

order to quantitatively assess loads of nutrients and sediment 

transported from these two major tributaries of the upper Cape 

Fear River basin. In addition, historical data collected by the 

USGS and NCDWQ were compiled and analyzed to evaluate 

whether loads and concentrations of nutrients and sediment 

have changed over the past approximately 30 years.

Purpose and Scope

This report presents (1) water-quality and streamflow 

data collected from August 2002 through August 2004 from 

the Haw River near Bynum and the Deep River at Moncure 

in North Carolina (fig. 1), and (2) an evaluation of historical 

data defining general water quality and suspended sediment, 

total suspended solids, and nutrient loads transported at these 

two sites between 1976 and 2004 to determine if loads and 

concentrations have changed. Because the two sampling sites 

are located at the most downstream part of each river subbasin (fig. 1), the data can be used to evaluate current (2004) 

water-quality characteristics in both rivers resulting from land 

use in the upstream areas. In addition, evaluation of historical 

data enables the UCFRBA to determine whether water-quality 

changes have occurred in the basins. 

Study Area

The upper Cape Fear River basin is located in the 

Piedmont Physiographic Province of North Carolina (fig. 1). 

The entire 3,100-square-mile (mi2) upper Cape Fear River 

basin (Upper Cape Fear River Basin Association, 2005) 

consists of the drainage area above the confluence of the Haw 

and Deep Rivers where they form the Cape Fear River (fig. 1). 

The headwaters of the Haw River originate near Greensboro, 

North Carolina (NC). From there, the river flows eastward 

through northern Guilford County and then southeast though 

Burlington in Alamance County and empties into Jordan Lake 

near Pittsboro in Chatham County (fig. 1). The headwaters of 

the Deep River also begin in Guilford County but near High 

Point, and the river flows southeast through Randolph County 

into Moore County where it turns and flows northeast along 

the border of Chatham and Lee Counties before joining the 

Haw River southeast of Moncure to form the Cape Fear River 

(fig. 1).

The study area includes the entire Deep River subbasin 

and only part of the Haw River subbasin—Jordan Lake and 

the creeks that drain into it are excluded (fig. 1). The approximately 2,700-mi2

 area (table 1A) of these two subbasins in 

2001a consisted primarily of forested areas (49.5 percent of 

the land use). Developed land and urban areas composed 

14.2 percent of the land use in the basin, and cultivated and 

planted lands composed 25.1 percent. The remaining area was 

composed of 1.9 percent water and wetlands and 0.3 percent 

barren land. Although these data are not directly comparable 

with 1992 dataa, forested areas generally decreased, developed 

(or urban) areas increased, and cultivated and planted lands 

remained about the same (table 1A). Human population in the 

more urban Haw River subbasin is almost twice the population of the Deep River subbasin and increased approximately 

30 percent and 18 percent in the Haw and Deep River 

subbasins, respectively, between 1990 and 2000 (table 1B). 

With respect to animal populations, the Deep River subbasin 

had about 7 times as many swine, 5 times as many poultry, 

and slightly fewer dairy cattle compared with the Haw River 

subbasin (table 1B). About 50 National Pollutant Discharge 

Elimination System (NPDES) wastewater dischargers are in 

each subbasin in the study area (fig. 1), and almost twice as 

much waste discharge is permitted in the Haw River subbasin 

compared with the Deep River subbasin (97 and 53 million 

gallons per day (Mgal/d), respectively; table 1B). 

Two stations were selected for streamflow measurement 

and water-quality sampling near the confluence of the two 

rivers—USGS streamgaging station 02096960 on the Haw 

a

At least three sources of land-use data were available for the study 

area—(1) National Multi-Resolution Land Characteristics (MRLC; 

Bara, 1994) based on Landsat Thematic Mapper (LT) data from 1992 

using nationally consistent land-use classes; (2) North Carolina 1996 

land-use/land-cover data based on 1993–95 LT land-cover classifications in Earth Satellite Corporation (1997) and used by the North 

Carolina Division of Water Quality (2005a); and (3) MRLC data 

based on 2001 Landsat 7 LT data using nationally consistent land-use 

classes. None of these datasets are directly comparable between years 

because land-use classifications may differ even though the category 

names may be identical. The 1992 and 2001 MRLC data were used 

to characterize general land-use characteristics in the Haw and Deep 

River subbasins for this report because they are based on consistently 

pre-processed Landsat 7 LT data that are nationally comparable and 

readily available, and consistently segregate unmanaged and managed 

land uses. 

   Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
Figure 1. Locations of sampling sites in the Haw River and Deep River subbasins of the upper Cape Fear 

River basin, North Carolina, 2002–04.

Introduction 
2004). Water-quality samples have been collected periodically 

at this site by the USGS since September 1976. The NCDWQ 

has collected quarterly to monthly samples for selected chemical constituents, including total suspended solids and nutrients, 

since July 1968 (North Carolina Division of Water Quality, 

2005b). 

The sampling site and streamgage on the Deep River 

at Moncure are located about 4.5 mi upstream from the 

confluence of the Haw and Deep Rivers (fig. 1). This site was 

established in July 1930, and streamflow data are still (2004) 

being collected at this site. Water-quality samples have been 

collected at this site by the USGS since June 1955; however, 

like the Haw River, samples were not collected with sufficient 

frequency for reliable load analysis until 1976 for sediment 

and 1981 for nutrients. Samples for total suspended solids 

and nutrients have been collected at this site by the NCDWQ 

since April 1992 (Andrea Thomas, North Carolina Division of 

Water Quality, written commun., July 2005). 

Table 1. Characteristics of (A) land use and (B) population and wastewater discharges in the Haw River and Deep River subbasins of 

North Carolina. 

[—, no category; land-use data are from 1992 and 2001 Multi-Resolution Land Characteristics (MRLC) land use/land cover coverages available from the U.S. 

Geological Survey’s Earth Resources Observation and Science (EROS) Data Center in Sioux Falls, South Dakota, and accessed in 2005 at http://edc.usgs.

gov/products/landcover.html]

A. Land use

Land-use class

Haw River subbasin Deep River subbasin Total 

Square miles Percentage Square miles Percentage percentages

1992 2001 1992 2001 1992 2001 1992 2001 1992 2001

Water 17 19.1 1.2 1.5 8.4 9.2 0.6 0.6 0.9 1

Developed 127.8 222.3 10.1 17.5 73.4 163.2 5.1 11.3 7.4 14.2

Barren 5.9 2 0.5 0.2 19.4 4.8 1.3 0.3 0.9 0.3

Forested 747.6 556.6 58.8 43.8 1,052.4 786.2 73 54.5 66.3 49.5

Planted/cultivated 358.4 358.9 28.2 28.2 272.1 321.6 18.9 22.4 23.3 25.1

Shrub/scrub — 47 — 3.7 — 78.1 — 5.4 — 4.6

Grassland/herbaceous — 53.1 — 4.2 — 66.2 — 4.6 — 4.4

Wetlands 15 13.2 1.2 1 16.6 13.1 1.1 0.9 1.2 0.9

Total 1,272 1,272 100 100 1,442 1,442 100 100 100 100

B. Population data and wastewater discharges permitted by the National Pollutant Discharge Elimination System (NPDES) [Data from 

North Carolina Division of Water Quality (2000, 2005a)] 

Population for year(s) shown

Humans 

1990 / 2000

Haw River subbasin Deep River subbasin

Swine 

1998

Dairy cattle 

1998

Poultry 

1998

Humans 

1990 / 2000

Swine 

1998

Dairy cattle 

1998

Poultry 

1998

391,737 / 506,453 10,250 10,160 5,737,248 216,528 / 256,143 71,129 7,059 31,461,122

NPDES-permitted wastewater discharges

Haw River subbasin Deep River subbasin

Number 53 50

Amount, in million gallons per day 97.3 52.9

   Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004

River near Bynum, which has a drainage areab of 1,275 mi2, 

and USGS streamgaging station 02102000 on the Deep River 

at Moncure, which has a drainage areab of 1,434 mi2 (fig. 1). 

These two stations drain about 2,700 mi2, or about 90 percent 

of the upper Cape Fear drainage basin. Because the Haw River 

above Jordan Lake (fig. 1) is the primary focus of this study, 

the 10 percent of the Haw River subbasin that includes Jordan 

Lake and streams draining Chapel Hill and Durham was 

excluded. 

The sampling site and streamgage on the Haw River near 

Bynum are located about 10 miles (mi) upstream from Jordan 

Lake (fig. 1). Streamflow data have been collected continuously at this site since October 1973 (Ragland and others, 

b

Drainage areas stored in the U.S. Geological Survey’s National Water 

Information System (NWIS) generally are determined from 1:24,000 topographic maps published by the U.S. Geological Survey. These drainage areas 

may vary from areas determined from other sources. Detailed site information 

for these stations are presented in Ragland and others (2004).
Acknowledgments

This study was conducted by the USGS in cooperation 

with the UCFRBA. The authors thank Carol Patrick, Mike 

Hite, and Sydney Miller of the UCFRBA for their cooperation 

in this study; Susan Gale and Andrea Thomas of the Environmental Sciences Section of the NCDWQ; and Tami Idol of the 

North Carolina Division of Land Resources. Further thanks 

go to the USGS field office staff in Raleigh, NC; to Mary 

Giorgino and Carolyn Oblinger of the USGS North Carolina 

Water Science Center for their support and guidance throughout this project; and to the reviewers of this report.

Methods

Methods that were used in the collection and interpretation of water-quality data are described here. Methods used for 

surface-water data collection and analysis and the statistical 

procedures to analyze the data also are included. 

Streamflow 

Streamflow, also referred to as stream discharge, was 

measured and recorded during this investigation according to 

standard USGS methods (Rantz and others, 1982). Both sites 

were equipped with data-collection platforms (DCPs) that 

record river stage at 15-minute intervals. Instantaneous streamflow was calculated at the time that stream-stage records 

were transmitted to the USGS National Water Information 

System (NWIS). Streamflow data have been collected at the 

Haw River near Bynum since 1973 and at the Deep River at 

Moncure since 1930 (Ragland and others, 2004).

Water-Quality Data

All water-quality data collected by the USGS in the 

study area during 2002–04 were collected in accordance with 

USGS protocols (U.S. Geological Survey, variously dated). 

Alkalinity, pH, specific conductance, dissolved oxygen, and 

temperature were measured in the field. Field properties and 

nutrient and suspended-sediment samples were collected 

approximately weekly from August 2002 to January 2004 and 

biweekly from January 2004 to August 2004. At each site, 

10 samples were collected for major ions and trace elements, 

7 of which were collected during periods of runoff. 

The equal-width-increment (EWI) method of sampling 

was used, because it ensures a depth- and width-integrated 

sample representative of the entire stream cross section. 

Isokinetic samplers were used to collect multiple vertical 

subsamples while wading the cross section or by deploying a 

sampler from the bridge during high flows. When conditions 

did not meet the criteria for EWI sampling (usually when 

water depths were too shallow), a weighted bottle sampler was 

used to collect multiple subsamples at equal widths in the river 

cross section. This approach yields samples that are representative of the cross section but are not depth integrated.

Water-quality samples were processed by compositing 

the subsamples, filtering appropriate samples through a 

0.45-micron filter, filling sample bottles, and preserving the 

samples. All sample processing was completed onsite and in 

accordance with USGS protocols and requirements outlined 

by the USGS National Water Quality Laboratory (NWQL) 

specific to the analysis being requested. Total suspendedsediment analyses were performed at the USGS Kentucky 

Water Science Center sediment laboratory in Louisville, Kentucky. Samples were analyzed for nutrients, major ions, and 

trace elements at the NWQL in Denver, Colorado (tables 2, 3). 

Analytical procedures used for data collected during this 

investigation are presented in Fishman (1993), and in Fishman 

and Friedman (1989) for data collected before 1989. Waterquality data collected for this investigation are presented in 

Appendixes 1–3. 

Table 2. Analytical methods and reporting levels for nutrients and suspended sediment. 

[ASF, automated segmented-flow spectrophotometry; mg/L, milligrams per liter; oC, degrees Celsius; pre-1989 reporting levels are 

in parentheses]

Constituent Method Reporting level

Ammonia plus organic nitrogen, total Colorimetry, ASF, microkjeldahl digestion 0.10 (0.20) mg/L

Ammonia, filtered Colorimetry, ASF, salicylate-hypochlorite 0.010 (0.01) mg/L

Nitrite plus nitrate, filtered Colorimetry, ASF, cadmium reduction-diazotization 0.060 (0.10) mg/L

Nitrite, filtered Colorimetry, ASF, low ionic-strength 0.002 (0.01) mg/L

Orthophosphate, filtered Colorimetry, ASF, phosphomolybdate 0.006 (0.01) mg/L

Phosphorus, total Colorimetry, ASF, microkjeldahl digestion 0.040 (0.01) mg/L

Total suspended sediment Filtration, evaporation at 105 oC; Gravimetric 1 (1 mg/L) mg/L

Methods   
Load-Estimation Techniques for Data Collected 

during 2002–04

Loads were calculated using LOADEST, a software 

program developed by the USGS (Runkel and others, 2004). 

The version of LOADEST used for this study fits the natural 

logarithm of load (concentration multiplied by streamflow) to 

a loglinear regression model using streamflow (Q), linear or 

decimal time (dtime), and various functions of these two variables automatically up to nine parameters (table 4). 

Additional user-defined variables can be 

included. The user can select the model 

based on his or her knowledge of the 

river system or use the model automatically selected by the LOADEST 

program. The model is calibrated using 

ordinary least-squares regression, and 

final load estimates are derived from 

retransforming the logarithm of the load 

back to actual loads according to one 

of three methods—(1) the maximum 

likelihood estimator (MLE), (2) the 

adjusted maximum likelihood estimator (AMLE), or (3) the least absolute 

deviation (LAD; Runkel and others, 

2004). LOADEST computes loads for 

each model by using the AMLE method and all observations 

in the dataset, and compares the models by using the Akaike 

information criterion (AIC). The model having the lowest 

value of the AIC statistic (representing the lowest model error) 

is selected for use in load estimation. Data collected during 

2002–04 from the Haw and Deep Rivers were analyzed using 

the AMLE method, which was selected for each of the load 

calculations because of the ability to use censored data with 

Table 3. Analytical methods and reporting levels for dissolved major ions and 

selected trace elements. 

[mg/L, milligrams per liter; μg/L, micrograms per liter]

Constituent Method Reporting level

Major ions 

Calcium Inductively coupled plasma/mass spectroscopy 0.02 mg/L

Magnesium Inductively coupled plasma/mass spectroscopy 0.008 mg/L

Sodium Inductively coupled plasma/mass spectroscopy 0.20 mg/L

Chloride Ion chromatography 0.20 mg/L

Sulfate Ion chromatography 0.18 mg/L

Trace elements

Aluminum Inductively coupled plasma/mass spectroscopy 1.6 μg/L

Arsenic Inductively coupled plasma/mass spectroscopy 0.2 μg/L

Cadmium Inductively coupled plasma/mass spectroscopy 0.04 μg/L

Chromium Graphite furnace atomic absorption 0.8 μg/L

Copper Inductively coupled plasma/mass spectroscopy 0.4 μg/L

Iron Inductively coupled plasma 6 μg/L

Lead Inductively coupled plasma/mass spectroscopy 0.08 μg/L

Manganese Inductively coupled plasma/mass spectroscopy 0.6 μg/L

Mercury Cold vapor atomic fluorescence 0.010 μg/L

Nickel Inductively coupled plasma/mass spectroscopy 0.06 μg/L

Table 4. List of regression models included in LOADEST computations.

[The natural logarithm (ln) of the load (Q * C) equals the following equations where a0 – a6 equals 

regression coefficients, lnQ equals natural logarithm of daily discharge, and dtime equals decimal time]

Model 

number Regression model

1 a0

 + a1lnQ

2 a0

 + a1lnQ + a2lnQ2

3 a0

 + a1lnQ + a2dtime

4 a0

 + a1lnQ + a2sin(2�dtime) + a3cos(2�dtime)

5 a0

 + a1lnQ + a2lnQ2 + a3dtime

6 a0

 + a1lnQ + a2lnQ2 + a3sin(2�dtime) + a4cos(2�dtime)

7 a0

 + a1lnQ + a2sin(2�dtime) + a3cos(2�dtime) + a4dtime

8 a0

 + a1lnQ + a2lnQ2 + a3sin(2�dtime) + a4cos(2�dtime) +a5dtime

9 a0

 + a1lnQ + a2lnQ2 + a3sin(2�dtime) + a4cos(2�dtime) +a5dtime + a6dtime2

   Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
negligible bias (Cohn, 1988). For the study dataset, where 

at least monthly samples were available for the entire period 

(1976–2004), the best model selected by LOADEST was 

used for load calculations for both stations on the Haw and 

Deep Rivers. Calendar year loads for 2002 and 2003 were 

estimated based on the calibration period September 2002 

through August 2004. The equations used to estimate loads are 

presented in Appendix 4.

Load-Estimation Techniques for Historical 

Data

Reconstruction of loads over time often is problematic 

because of large gaps in chemical or sediment data. Residuals 

(the difference between predicted and observed loads) cannot 

be computed for years when no data are available to calibrate 

the model or test the performance of the model. The question 

addressed in this report is whether suspended-sediment, nitrogen, and phosphorus loads changed between 1976 and 2004. 

In order to evaluate the effects of change, the loading models 

generated by using suspended-sediment data for 1976–85 

and total phosphorus and total nitrogen data for 1981–85 for 

the Haw River near Bynum, and suspended-sediment data 

for 1976–83 and total phosphorus and total nitrogen data for 

1981–83 for the Deep River at Moncure, and all nutrient and 

suspended-sediment data from both stations for 2002–04 were 

applied to the actual streamflow record for the entire period 

(1976–2004); the resulting load estimates were compared. For 

consistency with the statistical analysis of temporal change, 

described in the next section, the periods of comparison for 

suspended sediment are 1976–85 and 2002–04 for both stations. For hypothetical reconstruction of loads using historical 

streamflow data, automatic model selection by LOADEST was 

used for the Haw River near Bynum. In addition, loads calculated using the LOADEST program for years in which USGS 

data were available and reported were compared with loads 

calculated by previous researchers for sediment (Simmons, 

1993) and for sediment, total nitrogen, and total phosphorus 

(Childress and Treece, 1996). All of the basic load models 

used for hypothetical reconstruction of annual sediment, total 

nitrogen, and total phosphorus loads are given in Appendix 4. 

The AMLE method was used as the estimation method for all 

models. 

Historical sediment data for the Deep River at Moncure 

are available beginning in 1969, although the longest period 

of regularly collected monthly data occurred between 1981 

and 1983. Some summer and fall data are available for 

1976–78 and were included in the development of the model 

so that the total number of sediment samples was 25 for the 

period 1976–83. Data collected before 1976 were infrequent 

and appear to be event related; therefore, these data were 

not included. Historical data for nutrients in the Deep River 

at Moncure after 1980 are sparse (16 samples), and no 

USGS suspended-sediment or nutrient data were collected 

between 1984 and 2002. As a result, nutrient loads could 

not be computed for this site for the period 1976–83 because 

of insufficient data to run the LOADEST model. Because 

concentration and instantaneous load data for sediment were 

not available for almost 20 years, only flow was selected as the 

predictor variable (model 1, table 4) for estimating sediment 

loads. Sufficient sediment data were available (25 samples) 

to estimate loads generated from a model calibrated for the 

period 1976–83 for comparison with loads estimated from the 

model for the recent period (2002–04). 

Analysis of Temporal Changes

Typical approaches to sediment and water-quality 

sampling for estimating loads may not allow a reliable 

evaluation of changes in water quality (concentration) over 

time using trend tests, such as simple correlation analysis 

or two-sample tests used to test differences between two or 

more time periods. Most statistical techniques for hypothesis 

testing require random sampling through time so that all 

conditions have an equal probability of being represented. 

The assumption of randomness usually is not entirely true for 

water-quality sampling where load estimation is the intended 

goal because either extreme low or high flows are targeted for 

sampling to allow the development of regression equations 

for predicting loads or concentrations for load-calculation 

purposes, thus negating the assumption of randomness for 

statistical hypothesis testing. A preponderance of high- or 

low-flow samples will bias statistics generated from such data 

and may not be representative of the average conditions in the 

environment. It was assumed for the analysis conducted for 

this investigation that monthly sampling with some limited, 

targeted samples of very high and low flows, which probably 

is typical of most ambient-monitoring networks, was basically 

suitable for statistical hypothesis testing. Because chemical 

water-quality data were collected by the USGS from the Haw 

River near Bynum primarily during the 1987–94 high flows, 

these data were excluded from the statistical analysis using the 

Mann-Whitney test (Conover, 1980). 

Because loads are calculated by multiplying streamflow 

by nutrient concentration, loads are always correlated to flow 

and, thus, must be used carefully when assessing changes in 

magnitude through time. Decreases or increases in load may 

be a result of either corresponding decreases or increases in 

streamflow or nutrient concentrations. For this reason, trends 

in streamflow, loads, and nutrient concentrations were evaluated separately. 

For this report, trends in flow and concentration were 

considered suitable for evaluation (1) if regularly collected 

data (for example, monthly) were available for the period of 

record without a large number of targeted high or low flows, 

and (2) by applying a nonparametric Spearman’s rho correlation test (Conover, 1980) to daily flow or monthly concentrations of total nitrogen, total phosphorus, and suspended 

sediment with time. The hypotheses being tested for positive 

or negative trend with a correlation analysis are as follows:

Methods   
(1) H0

—The paired time and nutrient concentrations 

through the period of record are mutually independent and not 

correlated (null hypothesis).

(2) H1—(a) Larger values of concentration (or load) tend 

to be paired with larger values of time (increasing trend or 

positive correlation), or (b) smaller values of concentration (or 

load) tend to be paired with larger values of time (decreasing 

trend or inverse correlation; alternative hypothesis).

The Spearman’s rho correlation coefficient is calculated 

by using ranks of the raw data. A correlation of 1 or -1 indicates a perfect correlation or inverse correlation between two 

variables, and a zero indicates no correlation. For this report, 

a trend was considered significant if the p-value generated by 

the test was less than (<) 0.05 (that is, the significance level, 

or α, was 0.05).

If data are not available over time to test for monotonic 

trend with a Spearman’s rho or some other test, it may be 

possible to test differences in concentrations or loads for the 

two time periods being compared. If regularly collected data 

can be assumed to be basically random throughout the period 

(or periods) of record, a two-sample nonparametric MannWhitney test (Conover, 1980) can be applied to the datasets to 

test the following:

(3) H0—There is no difference in concentrations (or 

loads) between the two periods.

(4) H1—The concentrations (or loads) between the two 

periods are not identical.

It may be possible to divide the data into a before and 

after period, in which the approximate midpoint of a continuous period of record (for example, for the 

period 1990–2000, the midpoint is 1995), 

can be used to split the data for statistical 

comparison. Alternatively, when data are 

available for two separate periods, with 

no or inadequate data available for the 

period between (for example, 1980–85 

and 2000–03), the Mann-Whitney test can 

be applied to determine if water-quality 

conditions are different. For this report, the 

significance level of 5 percent (α = 0.05) 

was adopted so that values of p < 0.05 

were considered statistically significant 

and the null hypothesis (3) was rejected. 

In addition to the data collected by the 

USGS at the sites, total suspended solids, 

total nitrogen, and total phosphorus data 

collected by the NCDWQ also were compared in selected cases to verify conclusions about trends indicated by the USGS 

data or to evaluate possible differences in 

information conveyed about concentrations 

or trends by the two datasets.

Streamflow, Suspended Sediment, and 

Nutrient Concentrations and Loads 

in the Upper Cape Fear River Basin, 

2002–04

Sample collection began in August 2002 and ended in 

August 2004. Sampling occurred during unusually dry and 

wet years compared to the long-term record at both sites. The 

median streamflows for the Haw River near Bynum for water 

yearsc 2002, 2003, and 2004 were 169, 1,700, and 636 cubic 

feet per second (ft3/s), respectively (table 5; fig. 2). The 

median streamflow for this site from 1976 through 2002 was 

570 ft3/s (table 5). Based on available streamflow information 

(Ragland and others, 2003, 2004; Walters and others, 2005) 

water years 2002, 2003, and 2004 were very dry, very wet, 

and about average, respectively. The streamflow patterns at the 

Deep River at Moncure were similar to those of the Haw River 

(fig. 2). The median streamflows for the Deep River for water 

years 2002, 2003, and 2004 were 101, 1,430, and 542 ft3/s, 

respectively. The 1976–2004 median flow for the Deep River 

was 512 ft3/s (table 5; fig. 2). 

Annual streamflow variation can have several effects on 

water quality. For nutrients that are derived from continuous 

c

Water year is the period from October 1 through September 30 and is 

identified by the year in which the period ends. For example, the 2002 water 

year began October 1, 2001, and ended September 30, 2002.

Table 5. Selected streamflow statistics for the Haw River near Bynum and the 

Deep River at Moncure, North Carolina. 

[Mean daily streamflows were used to compute statistics for each water year shown]

Streamflow, 

in cubic feet 

per second

Water years 

1976–2004

Water year 

2002

Water year 

2003

Water year 

2004

Haw River near Bynum

Minimum 0.18 60 106 174

Mean 1,259 370 2,950 938

Median 570 169 1,700 636

Maximum 58,000 6,900 33,300 10,700

Number of values 10,593 365 365 366

Deep River at Moncure

Minimum 18 22 37 105

Mean 1,426 391 3000 1,020

Median 512 101 1,430 542

Maximum 36,800 11,500 29,000 13,000

Number of values 10593 365 365 366

   Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
discharge sources (point-source discharges or contaminated 

ground water), the concentrations generally will be higher 

(having potential short-term biological effects), and the 

loads will be lower during dry years. Conversely, nutrient 

concentrations generally will be lower and the loads will be 

higher during wet years. For nutrients and sediment derived 

from diffuse or nonpoint sources associated with runoff, both 

concentrations and loads generally will be lowest during dry 

years and highest during wet years. 

Five water-quality samples per year were collected at 

both sites for 2 years and analyzed for selected major ions 

and trace elements to characterize general water quality in the 

Haw and Deep Rivers. The analytical results for these samples 

are given in Appendix 3A (Haw River) and 3B (Deep River). 

Because of the small number (10) of samples collected during 

this investigation, reliable load estimates for these constituents 

could not be made. In general, the water types of the Haw and 

Deep Rivers are similar and have the same overall characteristics—a mixed ionic water type (calcium-magnesium-sodiumpotassium-bicarbonate-sulfate-chloride). Calcium was the 

dominant cation during high flows, which typically occurred 

during the winter and spring months, and sodium was the 

dominant cation during low flows, which typically occurred 

during the summer and fall months (fig. 3). As noted in Childress and Treece (1996), the dominant water types for streams 

affected by point sources in the study area are sodium plus 

potassium and sulfate, whereas streams minimally affected 

by point sources have a calcium and bicarbonate-dominated 

water type. From the trace element data (Appendix 3A, B), 

no dissolved constituent concentrations were measured that 

exceeded current (2004) water-quality standards for drinking 

water or aquatic life established by either the NCDWQ or the 

U.S. Environmental Protection Agency (USEPA).

Nutrient and Suspended-Sediment 

Concentrations

Nutrient and suspended-sediment samples were collected 

from the Haw and Deep Rivers over a 2-year period, beginning 

in August 2002 and ending in August 2004 (table 6). Median 

concentrations of total nitrogen and ionic forms of nitrogen 

and suspended sediment appear to be similar at both sites and 

are not significantly different (p greater than (>) 0.05). On the 

other hand, orthophosphate and total phosphorus concentrations in water samples from the Deep River were significantly 

(p < 0.05) higher. This difference can be seen more clearly 

in the box plots shown in figure 4, where the difference in 

total phosphorus concentrations between the two sites is more 

apparent than the differences in total nitrogen and suspendedsediment concentrations. 

Seasonal concentrations of suspended sediment, orthophosphate, and total nitrogen varied (fig. 5). (Orthophosphate 

was the only form of phosphorus available during the period 

2002–04 and is included here for comparison of the effects of 

the very dry summer in 2002.) Suspended-sediment concentrations, except during spring and summer 2003, tended not to 

vary greatly from one season to the next. The occurrences of 

relatively high concentrations of suspended sediment during 

the high flows of the unusually wet spring and summer of 

2003 (fig. 5) are indicative of nonpoint sources (for example, 

erosion from hillsides or banks). Concentrations of total nitrogen and orthophosphate were higher during the 2002 and 2004 

summers, previously noted as dry to average years, and lower 

during 2003. This generally indicates the influence of continuous discharge (wastewater from point sources or ground water) 

on nutrient concentrations, particularly during low flows. 

Wastewater is a continuous source of both nitrogen and 

phosphorus concentrations in the Haw and Deep Rivers, and 

substantially higher orthophosphate concentrations occurred 

in the Deep River during all seasons (fig. 5). This finding is 

consistent with information presented by the North Carolina 

Department of Environment and Natural Resources (2004). 

Very high (median > 1.5 milligrams per liter (mg/L)) concentrations of total phosphorus occurred between 1998 and 

2003 in the Deep River near High Point, NC, and remained 

high downstream at Ramseur (North Carolina Department of 

Figure 2. Streamflow in the (A) Haw River near 

Bynum and (B) Deep River at Moncure, North 

Carolina, for water years 2002–04.

Streamflow, Suspended Sediment, and Nutrient Concentrations and Loads in the Upper Cape Fear River Basin, 2002–04   
Figure 3. Water types for the (A) Haw River near Bynum and (B) Deep River at Moncure, North Carolina, 2002–04.

Table 6. Statistical summary of nutrient and suspended-sediment concentrations in the Haw and Deep Rivers, North Carolina, 

2002–04. 

[+, plus; all values are in milligrams per liter. At each sampling site, 86 values were used to compute statistics for suspended sediment and for each nutrient 

shown]

Nitrogen, 

ammonia, 

dissolved 

Nitrogen, 

ammonia 

plus 

organic, 

total

Nitrogen, 

nitrite 

+ nitrate, 

dissolved 

Nitrogen, 

nitrite, 

dissolved 

Total 

nitrogen 

Orthophosphate, 

dissolved

Total 

phosphorus

Suspended 

sediment

Haw River near Bynum

Minimum 0.005 0.10 0.22 0.0020 0.86 0.012 0.04 3

Mean 0.047 0.66 0.91 0.010 1.6 0.092 0.16 36

Median 0.031 0.60 0.75 0.0075 1.4 0.067 0.13 14

Maximum 0.40 1.7 3.5 0.044 4.5 0.46 0.44 350

Deep River at Moncure

Minimum 0.005 0.31 0.18 0.0020 0.81 0.048 0.08 1

Mean 0.042 0.70 0.90 0.0081 1.6 0.17 0.23 38

Median 0.022 0.60 0.82 0.0080 1.5 0.13 0.21 12

Maximum 0.405 2.7 2.14 0.028 3.9 0.81 0.54 468

10 Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
Environment and Natural Resources, 2004). Total phosphorus 

concentrations decreased to about 0.15 mg/L downstream 

from Ramseur but increased again to above 0.2 mg/L at the 

NCDWQ monitoring station near Sanford, NC, and remained 

at this concentration at the NCDWQ monitoring station farther 

downstream at Moncure. In the Haw River, total phosphorus 

concentrations were much lower; the median total phosphorus 

concentration ranged from about 0.1 mg/L in the upper 

reaches to about 0.25 mg/L at the NCDWQ monitoring station 

near Burlington, NC, and decreased to about 0.17 mg/L at the 

monitoring station near Bynum (North Carolina Department of 

Environment and Natural Resources, 2004). 

Anthropogenic sources of nutrients and sediment affect 

water quality, but a greater overall effect was observed in the 

Deep River. Both the Haw and Deep Rivers had concentrations 

of suspended sediment, total nitrogen, and total phosphorus 

above estimated background concentrations—those that would 

occur in piedmont streams draining undeveloped forested 

watersheds. Based on the median concentrations presented 

for the Haw River near Bynum (table 6) and estimated 

background concentrations of about 0.5 mg/L for total 

nitrogen and 0.05 mg/L for phosphorus reported by Simmons 

and Heath (1982) for streams draining the study area in the 

Piedmont Physiographic Province, 50 percent of the nitrogen 

(2 times the background) and more than 66 percent of the 

phosphorus (3 times the background) concentrations are 

derived from anthropogenic sources. The median concentration of suspended sediment in the Haw River near Bynum 

(14 mg/L, table 6) approximated about 2 to 3 times the median 

suspended-sediment concentration (5–6 mg/L) reported by 

Simmons (1993) for piedmont forested watersheds (assumed 

to represent background or pre-development conditions). 

Stated another way, anthropogenic sources currently (2004) 

compose about 50–66 percent of the sediment load in the Haw 

River. 

For the Deep River at Moncure, the median concentrations of total nitrogen and total phosphorus (table 6) were 

approximately 3 times the background total nitrogen and 

more than 4 times the background total phosphorus concentrations reported by Simmons and Heath (1982)—higher 

nutrient enrichment than observed in the Haw River. Based 

on information presented in Simmons (1993), the median 

suspended-sediment concentration in the Deep River at 

Moncure (12 mg/L, table 6) approximated about 2 times 

that reported for piedmont forested watersheds (5–6 mg/L). 

Possible reasons for these differences are discussed at the end 

of the next section.

Figure 4. (A) Total phosphorus, (B) total nitrogen, and (C) suspended-sediment concentrations in the Haw River near Bynum and 

the Deep River at Moncure, North Carolina, 2002–04.

Streamflow, Suspended Sediment, and Nutrient Concentrations and Loads in the Upper Cape Fear River Basin, 2002–04 11
Figure 5. Seasonal concentrations of (A) suspended sediment, (B) orthophosphate, and (C) total nitrogen in the Haw River 

near Bynum and the Deep River at Moncure, North Carolina, 2002–04.

12 Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
Nutrient and Suspended-Sediment Loads 

Loads of total nitrogen, total phosphorus, and suspended 

sediment in the Haw and Deep Rivers were estimated for the 

2002 and 2003 calendar years and seasonally for the period 

2002–04. Seasons are represented by quarters, using 3-month 

intervals beginning September 2002 and ending in August 

2004. The transport equations used to estimate loads are given 

in Appendix 4.

Annual Loads

During the 2002 calendar year, the Haw River near 

Bynum transported 1,400 tons of total nitrogen, 160 tons of 

total phosphorus, and 56,000 tons of suspended sediment 

(table 7). In 2003, the river transported 3,400 tons of total 

nitrogen, 470 tons of total phosphorus, and 230,000 tons 

of suspended sediment. The yields for total nitrogen were 

1.1 tons per year per square mile (tons/yr)/mi2 in 2002 and 

Table 7. Nutrient and sediment loads and yields in the Haw and Deep Rivers, North Carolina, for calendar years 2002 and 2003.

[%, percent; tons/yr, tons per year; (tons/yr)/mi2, tons per year per square mile; +, plus]

Haw River near Bynum Deep River at Moncure

Constituent

Confidence 

interval, 

lower 95%

Confidence 

interval, 

upper 95%

Load 

(tons/yr)

Yield 

([tons/yr]/mi2)

Confidence 

interval, 

lower 95%

Confidence 

interval, 

upper 95%

Load 

(tons/yr)

Yield 

([tons/yr]/mi2)

2002

Nitrogen, ammonia, 

dissolved 31 86 54 0.042 38 110 66 0.046

Nitrogen, ammonia 

+ organic, total 570 770 670 0.53 830 1,100 960 0.67

Nitrogen, NO2 + 

NO3, dissolved 590 760 680 0.53 590 830 700 0.49

Nitrogen, nitrite, 

dissolved 8.4 14 11 0.0086 7.3 12 9.6 0.0067

Total nitrogen 1,200 1,500 1,400 1.1 1,500 1,900 1,700 1.2

Orthophosphate, 

dissolved 43 72 56 0.044 97 130 110 0.1

Total phosphorus 130 200 160 0.13 220 300 260 0.18

Suspended 

sediment 29,000 97,000 56,000 44 52,000 140,000 88,000 61

2003

Nitrogen, ammonia, 

dissolved 96 300 180 0.14 120 410 230 0.16

Nitrogen, ammonia 

+ organic, total 1,700 2,200 1,900 1.5 2,300 2,900 2,600 1.8

Nitrogen, NO2 + 

NO3, dissolved 1,300 1,700 1,500 1.2 1,400 1,800 1,600 1.1

Nitrogen, nitrite, 

dissolved 20 32 26 0.020 18 29 23 0.016

Total nitrogen 3,100 3,900 3,400 2.7 3,600 4,400 4,000 2.8

Orthophosphate, 

dissolved 110 170 140 0.11 230 310 270 0.19

Total phosphorus 400 590 470 0.37 590 910 740 0.52

Suspended 

sediment 140,000 350,000 230,000 180 220,000 600,000 380,000 270

Streamflow, Suspended Sediment, and Nutrient Concentrations and Loads in the Upper Cape Fear River Basin, 2002–04 13
2.7 (tons/yr)/mi2 in 2003. Total phosphorus yields were 

0.13 (ton/yr)/mi2 in 2002 and 0.37 (ton/yr)/mi2 in 2003. 

Suspended-sediment yields were 44 (tons/yr)/mi2 in 2002 and 

180 (tons/yr)/mi2 in 2003 (table 7). 

The Deep River at Moncure transported 1,700 tons of 

total nitrogen, 260 tons of total phosphorus, and 88,000 tons 

of suspended sediment during the 2002 calendar year. In 2003, 

the river transported 4,000 tons of total nitrogen, 740 tons of 

total phosphorus, and 380,000 tons of suspended sediment. 

The yields for total nitrogen were 1.2 (tons/yr)/mi2 in 2002 

and 2.8 (tons/yr)/mi2 in 2003. The yields for total phosphorus 

were 0.18 (ton/yr)/mi2 in 2002 and 0.52 (ton/yr)/mi2 in 2003. 

Suspended-sediment yields were 61 (tons/yr)/mi2 in 2002 and 

270 (tons/yr)/mi2 in 2003 (table 7). The loads of all chemical 

constituents at each site were significantly higher in 2003 than 

in 2002, primarily because of the much higher flows during 

2003 (fig. 2). 

Comparison among sites can be accomplished by 

evaluating yields, which normalize for differences in drainage 

area. Yields of total nitrogen, total phosphorus, and suspended 

sediment generally were higher in the Deep River than in 

the Haw River (table 7), and yields of orthophosphate, total 

phosphorus, and sediment were substantially higher during 

the study period. These differences are the result primarily of 

lower concentrations in the Haw River, even though the Haw 

River had higher streamflows (fig. 2). It is not known why 

the Haw River had generally lower annual yields for nutrients 

and sediment than the Deep River, given that the Haw River 

subbasin has more developed and cultivated land and less 

forested land than the Deep River subbasin (table 1A). The 

Haw River also is permitted for a total effluent discharge of 

about 93 Mgal/d compared with 53 Mgal/d in the Deep River 

(North Carolina Division of Water Quality, 2005b). Based 

on this information, one might expect poorer water quality 

in the Haw River, although this is not supported by the data 

presented in this report. Because the Haw River is classified as Nutrient Sensitive Water by the NCDWQ, however, 

point-source dischargers along the Haw River are under more 

stringent discharge limits, particularly in regard to phosphorus, 

than along the Deep River (Michelle Woolfolk, North Carolina Division of Water Quality, oral commun., April 2005); 

this appears to be a major factor in accounting for lower 

phosphorus concentrations in the Haw River. Even though 

the Haw River subbasin has more people, developed lands, 

and cultivated lands than the Deep River subbasin, the Deep 

River subbasin above Moncure has 6 times as many swine and 

5.5 times as many poultry (table 1B), which are major potential sources of nutrients in watersheds (Mallin, 2000). Another 

factor that may contribute to water-quality differences between 

the two subbasins is the number of impoundments along the 

two rivers—the Haw River has 59 and the Deep River has 34 

(Tammy Idol, North Carolina Division of Land Resources, 

written commun., 2005). Additional studies that focus on why 

some of these water-quality differences exist could provide 

valuable information for future management of the upper Cape 

Fear River basin.

Seasonal Loads

Nutrient and suspended-sediment loads were computed 

seasonally for the Haw River near Bynum and the Deep River 

at Moncure. The seasons were divided into spring, summer, 

fall, and winter, and each season was composed of a 3-month 

period beginning in September 2002 and ending in August 

2004 for a total of eight seasons.

The highest loads estimated for the Haw River during 

this period were 1,500 tons of total nitrogen, 234 tons of total 

phosphorus, and 140,000 tons of suspended sediment, all of 

which occurred during spring 2003 (table 8). The lowest loads 

transported in the Haw River during the period were 240 tons 

of total nitrogen, 26 tons of total phosphorus, and 3,100 tons 

of suspended sediment. The lowest total phosphorus and 

suspended-sediment loads occurred in spring 2004, and the 

lowest total nitrogen load occurred in summer 2004 (table 8).

The highest loads in the Deep River during this investigation also occurred in spring 2003 for all constituents—

1,800 tons of total nitrogen, 436 tons of total phosphorus, 

and 260,000 tons of suspended sediment. The lowest loads 

transported in the Deep River during this period were 240 tons 

of total nitrogen, 33 tons of total phosphorus, and 6,700 tons 

of suspended sediment. The lowest range of loads during the 

study occurred in spring 2004 for suspended sediment and in 

summer 2004 for total phosphorus and total nitrogen (table 8).

During this investigation, loads of all constituents at 

both sites were greatest during the spring and summer 2003, 

an unusually wet year with a very wet spring and summer, 

and lowest during the fall and winter months (fig. 6). During 

2004, a more typical year hydrologically, primary transport of 

nutrient and sediment loads occurred during the fall and winter 

months. Because water year 2003 was much wetter than water 

year 2004, substantially greater loads were transported during 

the first four seasons than during the last four at both sites. 

Both sites had the largest loads of all constituents transported 

during spring 2003 (table 8).

14 Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
Table 8. Seasonal loads of nutrients and suspended sediment in the Haw River near Bynum and the Deep River at Moncure, North 

Carolina, during September 2002–August 2004.

[+, plus; all values are in tons]

Season

Nitrogen, 

ammonia 

dissolved

Nitrogen, 

ammonia + 

organic, total

Nitrogen, 

NO2 + NO3, 

dissolved

Nitrogen, 

nitrite 

dissolved

Total 

nitrogen

Orthophosphate, 

dissolved

Total 

phosphorus

Suspended 

sediment

Haw River near Bynum

September 2002 – 

November 2002 29 340 260 3.6 590 26 87 41,000

December 2002 – 

February 2003 30 350 350 6.3 740 25 80 21,000

March 2003 – 

May 2003 100 950 540 14 1,500 49 234 140,000

June 2003 – 

August 2003 38 500 420 5.4 900 42 134 56,000

September 2003 – 

November 2003 16 220 230 2.0 440 25 58 21,000

December 2003 – 

February 2004 13 180 250 2.8 440 20 40 6,200

March 2004 – 

May 2004 7.6 110 190 2.0 310 15 26 3,100

June 2004 – 

August 2004 6.1 100 150 0.97 240 18 27 4,800

Deep River at Moncure

September 2002 – 

November 2002 31 480 300 3.9 770 52 108 53,000

December 2002 – 

February 2003 44 530 450 5.0 1,000 53 154 45,000

March 2003 – 

May 2003 150 1,400 580 12 1,800 110 436 260,000

June 2003 – 

August 2003 39 660 410 6.2 1,300 85 143 76,000

September 2003 – 

November 2003 10 200 240 1.7 430 34 49 13,000

December 2003 – 

February 2004 13 190 340 1.8 510 27 64 8,200

March 2004 – 

May 2004 9.9 140 220 1.6 360 24 51 6,700

June 2004 – 

August 2004 6 110 150 0.95 240 24 33 9,100

Streamflow, Suspended Sediment, and Nutrient Concentrations and Loads in the Upper Cape Fear River Basin, 2002–04 15
HAW RIVER DEEP RIVER

Figure 6. Seasonal loads of suspended sediment, total phosphorus, and total nitrogen in the Haw River near Bynum 

and the Deep River at Moncure, North Carolina, for water years 2003 and 2004.

collected (monthly to quarterly) suspended-sediment data 

are available for the Haw and Deep River sites beginning in 

1976, although substantially fewer analyses are available for 

the Deep River at Moncure. Regularly collected total nitrogen 

and total phosphorus data for the Haw and Deep Rivers are 

available from 1981.

The general time period between 1976 and 2004 was 

considered to be appropriate for comparing changes in water 

quality, particularly in light of 25–30 years of changes in land 

use and population, improvements in wastewater-treatment 

plants, regulations banning phosphorus in detergents in 1988 

(Childress and Treece, 1996), implementation of nonpointsource controls as best-management practices, changes in 

planted agricultural acreage, and other major changes. The 

Historical Changes in Streamflow, 

Suspended-Sediment, and Nutrient 

Concentrations and Loads, 1976–2004

Although continuous streamflow data are available from 

the USGS for the Haw River near Bynum since 1973 and 

for the Deep River at Moncure since 1930, the availability 

of water-quality data from the USGS at these sites is more 

limited. The utility of long-term water-quality and streamflow 

data is that environmental effects of changes in land use or 

management practices on water quality can be evaluated 

throughout the period for which data are available. Regularly 

16 Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
approximate midpoint of this period is 1990, which formed 

the primary division of data for two-sample comparisons of 

change or for calibration of data between the time periods 

compared in this report. 

The analysis presented here attempts to answer the question of whether water quality has changed in the Haw River 

near Bynum or in the Deep River at Moncure since 1976. Possible trends or changes in concentrations through time were 

evaluated by statistically examining streamflow, total nitrogen, 

total phosphorus, and suspended-sediment concentrations 

and loads for the period 1976–2004 for sediment and for the 

period 1981–2004 for total nitrogen and total phosphorus, 

using trend-detection techniques as described previously. It 

is intended that this analysis also will provide a baseline for 

measuring possible future changes.

Streamflow in the Haw River near Bynum

Using annual streamflows in the Haw River near Bynum 

for the period 1976–2004 (fig. 7), a slight, but significant 

decrease in mean daily streamflow was detected using 

Spearman’s rho (ρ = - 0.04, p < 0.05). Based on the information shown in figure 7, streamflows were among the lowest in 

2002 (similar to those during the late 1980s) and among the 

highest in 2003 when water-quality samples were collected 

as part of this investigation. A wide range of flows, therefore, 

is represented in the water-quality samples collected during 

2002–04. Even though a significant negative trend in streamflow was detected at the Haw River near Bynum for the period 

1976–2004, it was very small (p < - 0.05). This slight longterm trend is assumed to have no discernible effect on water 

quality. Therefore, a general assumption for trend analysis is 

that any trend in concentration or load at this site is not related 

to a trend in streamflow; thus, some other factor is assumed to 

be responsible for the observed water-quality trend. 

Suspended Sediment in the Haw River near 

Bynum

Suspended-sediment concentration data for the Haw 

River near Bynum are available from the USGS for the period 

1976–94, collected at approximately monthly intervals during 

1978–79 and from 1981 to 1985, monthly during 1988–89, 

and quarterly between 1992 and 1994. One sample was 

collected in 1998. Only high flows were sampled for sediment 

between 1988 and 1998. These data are not suitable for trend 

analysis of concentrations, however, because low to moderate 

flows were not represented during these years. Samples were 

collected weekly to biweekly as part of this study between 

2002 and 2004. Monthly data for total suspended solids also 

Figure 7. Annual streamflow in the Haw River near Bynum, North Carolina, 1976–2004.

Historical Changes in Streamflow, Suspended-Sediment, and Nutrient Concentrations and Loads, 1976–2004 17
are available from the NCDWQ for 1980–2004. Because the 

NCDWQ data were collected monthly through the period, 

these data are suitable for either analysis of monotonic trend 

or a before and after analysis using a two-sample test. The 

relations of NCDWQ total suspended-solids data and USGS 

suspended-sediment data to streamflow data collected by the 

USGS are shown in figure 8, which indicates a similar positive 

correlation with streamflow and good comparability at this 

site. In general, however, total suspended-solids data are not 

considered to be a suitable measure of suspended material 

in open-channel environments because of negative or low 

bias—total suspended-solids and suspended-sediment data 

from natural waters are not comparable and should not be 

used interchangeably (Gray and others, 2000). It was assumed, 

however, that a low bias may not necessarily affect the occurrence of possible time trends and that total suspended-solids 

data may be useful for trend comparisons.

A Mann-Whitney test (Conover, 1980) was applied to test 

for differences in suspended-sediment concentration between 

the 1976–85 data and the 2002–04 data from the USGS. 

Data collected between 1988 and 1998 were not suitable for 

inclusion in the analysis, as indicated previously. Suspendedsediment concentrations have decreased significantly 

(p < 0.004) since the early 1980s from a median of 40 mg/L 

to 14 mg/L during 2002–04 (fig. 9A). This decrease in 

suspended-sediment concentration is parallel to a significant 

decrease (p < 0.0001) in total suspended-solids concentration from a median of 10 mg/L to 7 mg/L (fig. 9B). Because 

suspended sediment is highly correlated to streamflow, the 

decrease in concentrations could be attributed to flow differences alone if streamflows were different between the two 

Figure 8. Relation of (A) suspended-sediment data collected by the U.S. Geological Survey and (B) total 

suspended-solids data collected by the North Carolina Division of Water Quality to streamflow at the Haw River 

near Bynum, North Carolina, 1981–2004.

18 Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
periods (1981–85 and 2002–04). Lower concentrations could be correlated to lower flows during the 

later period. Based on analysis of the data from the 

two periods, however, there was no significant difference (p > 0.05) in instantaneous streamflow values 

(streamflow measurements made at the time samples 

were collected). Thus, the difference was not due to 

differences in streamflow. 

Suspended-sediment concentrations for 1976–85 

and 2002–04 were subdivided into four different 

streamflow ranges to compare concentration characteristics within each streamflow category. Higher 

median concentrations of suspended sediment and 

a greater range in streamflows occurred during the 

1976–85 period compared with the 2002–04 period 

(fig. 10). These results confirm that suspendedsediment concentrations were higher before 1985 in 

comparison with the 2002–04 period, particularly 

with respect to streamflow greater than 5,000 ft3/s. 

Suspended-sediment concentrations have 

decreased since the early 1980s, as demonstrated in 

the previous discussion; therefore, generally lower 

loads for the later calibration period (2002–04) 

would be expected. Suspended-sediment loads were 

computed twice to test this hypothesis—first using the 

LOADEST program to select the best of nine regression models (table 4) using the 1976–89 data early 

in the period (Appendix 4), and then using the 

LOADEST-selected best regression model using 

only the 2002–04 data (Appendix 4) and applying 

Figure 9. (A) Suspended-sediment concentrations for 1976–85 and 2002–04 from the U.S. 

Geological Survey, and (B) total suspended-solids concentrations for 1981–91 and 1992–2004 from 

the North Carolina Division of Water Quality at the Haw River near Bynum, North Carolina.

Figure 10. Suspended-sediment concentrations at four different 

streamflow ranges for (A) 1976–85 and (B) 2002–04 in the Haw River near 

Bynum, North Carolina.

Historical Changes in Streamflow, Suspended-Sediment, and Nutrient Concentrations and Loads, 1976–2004 19
each model to the entire period of record (1976–2003) for 

streamflow (table 9). The loads generated for years having 

calibration data are actual estimated loads (because data were 

collected during the same period) and are shaded in table 9. 

The load values that are not shaded are hypothetical estimates 

based on streamflow and the regression model calibrated with 

data only from the period indicated.

Hypothetical suspended-sediment loads that would have 

been transported during the streamflow period 1976–2003 

(median load using 2002–04 calibration data was 66,483 tons, 

table 9) were about 75 percent lower than loads calculated 

using the 1976–89 calibration data (median load for the 

entire streamflow period 1976–2003 was 287,132 tons, 

table 9). Because it has been shown that suspended sediment 

is significantly correlated to flow, however, it 

is possible that part of this difference is a result 

of lower streamflows during 2002 and 2003 compared with 1976–89 flows. In fact, the median 

flow was only slightly (about 15 percent) lower 

during 2002–03 (1,140 ft3/s, primarily because of 

the generally high flows during 2003) compared 

with the median flow for the period 1976–89 

(1,307 ft3/s), further supporting the conclusion that suspended-sediment concentrations 

decreased as a result of some other factor. 

The average calendar-year loads for 1976–

89 generated from the LOADEST calibration in 

this analysis when compared with the average 

water-year loads from Childress and Treece 

(1996) were about 20 percent lower for the same 

period (1989–94). The load estimates from 

Childress and Treece (1996), however, fall within 

the 95-percent confidence interval generated 

by LOADEST. Loads generated for the period 

1976–79 (218,000 tons) using the 1976–89 

model were about 17 percent higher than the 

estimated average annual load (180,000 tons) for 

the Haw River near Bynum reported by Simmons 

(1993) for the period 1970–79, again well within 

the expected 95-percent confidence interval.

The observed decrease in suspendedsediment loads between 1976–89 and 2002–04 in 

the Haw River may be a result of several factors. 

Cropland decreased substantially between 1980 

and 2000—planted crop acreage in the basin 

decreased about 20 percent between 1982 and 

1997 based on National Resource Inventory 

(NRI) data from the U.S. Department of Agriculture (USDA) (North Carolina Division of Water 

Quality, 2005a). Most of this decrease occurred 

in the 1980s. Based on crop statistics from the 

USDA for counties in the upper Cape Fear River 

basin (U.S. Department of Agriculture, 2004), 

total planted acreage decreased from about 

330,000 acres in 1980 to about 245,000 acres in 

1990, or about 24 percent (Appendix 5). 

Erosion associated with farming practices 

is well documented (Welsch, 1991; Lal, 1995; 

Pimentel and others, 1995), and it is likely that 

the decrease in cultivated land in the basin is a 

major factor in the observed suspendedsediment decrease during the study period. 

Annual erosion from forests is about 40 pounds 

Table 9. Annual suspended-sediment loads for calendar year 1976–2003 

streamflows in the Haw River near Bynum, North Carolina, for two calibration 

periods, 1976–89 (shaded) and 2002–04 (shaded).

[Annual water-year loads from Childress and Treece (1996) are given for comparison] 

Calendar 

year

Suspendedsediment 

load, 

in tons,

1976–89

Suspendedsediment 

load, 

in tons,

2002–04

Suspendedsediment 

load, 

in tons,

from Childress 

and Treece (1996)

1976 26,184 17,731

1977 43,051 23,063

1978 364,851 150,976

1979 438,146 164,179

1980 76,776 35,177

1981 124,482 41,013

1982 346,573 115,131

1983 166,966 66,483

1984 441,460 135,661

1985 272,081 78,970

1986 18,596 8,271

1987 561,460 133,412

1988 28,792 11,475

1989 437,338 112,095 406,000

1990 287,132 73,123 377,000

1991 229,357 57,713 425,000

1992 181,897 45,150 206,000

1993 374,586 86,448 479,000

1994 213,940 48,307 280,000

1995 947,247 139,387

1996 2,709,284 268,932

1997 273,049 51,817

1998 722,783 119,955

1999 389,255 58,459

2000 147,424 29,103

2001 119,098 22,254

2002 E 403,078 55,977

2003 E 1,723,580 225,375

E Calendar year loads for 2002 and 2003 were estimated based on the calibration period 

September 2002 through August 2004.

20 Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
per acre compared with about 14,000 pounds per acre from 

cropland in the United States (Pimentel and others, 1995). 

Even though population and urbanization increased in the 

basin (North Carolina Division of Water Quality, 2000, 

2005a), these factors are overshadowed by the dramatic 

decrease in agricultural land use in the basin that occurred 

during the 1980s and by improvements in crop-management 

practices since the 1980s. These findings are in agreement 

with those of Richter and others (1995), who determined that 

sediment transport in the Yadkin River basin in the North 

Carolina Piedmont decreased by about 30 percent from the 

1950s to the 1990s, primarily because of an approximate 

50-percent decrease in cropland during the period and 

improvements in crop-management practices since the early 

1990s, even though residential and urban areas increased by 

80 percent.

Total Phosphorus in the Haw River near Bynum

Total phosphorus data are available for the Haw River 

near Bynum from the USGS for three periods—monthly 

between 1981 and 1986, quarterly between 1992 and 1995, 

and monthly or biweekly from August 2002 through August 

2004. Monthly phosphorus data for the Haw River also are 

available from the NCDWQ for January 1980 through 2004. 

Both total phosphorus concentrations and loads decreased 

in the Haw River between 1980 and 2004. Total phosphorus 

concentrations decreased significantly between the periods 

1976–85 and 2002–04 (p < 0.001) from a median of 

0.34 mg/L to a median of 0.13 mg/L, according to USGS data 

and corroborated by NCDWQ data (fig. 11). Using load data 

computed by LOADEST, the decrease in phosphorus loads 

Figure 11. Total phosphorus data from (A) the North Carolina Division of Water Quality and (B) the U.S. 

Geological Survey for the Haw River near Bynum, North Carolina, 1980–2004, and trends indicated by 

LOWESS smooth lines.

Historical Changes in Streamflow, Suspended-Sediment, and Nutrient Concentrations and Loads, 1976–2004 21
between 1981–85 and 2002–04 was similar to the decrease in 

sediment—more than 50 percent for annual loads (table 10). 

The total phosphorus loads reported by Childress and Treece 

(1996) are between the 1981–85 and 2002–04 model calculations. The lower phosphorus loads observed during 2002–04 

compared with those in the 1980s are consistent with data 

from other studies, both nationally and locally. 

Dissolved phosphorus concentrations decreased nationwide in many streams in response to a ban on phosphorus in 

detergents in 1988 (Smith and others, 1993). This decrease 

also was noted by Childress and Treece (1996) for streams 

draining into Jordan Lake, including the Haw River near 

Bynum. Data from both the USGS and NCDWQ indicate a 

significant decrease in total phosphorus concentrations in the 

basin since 1980, primarily because of decreased point-source 

discharges. The median orthophosphate concentration (the dissolved portion of total phosphorus) decreased from 0.2 mg/L 

during 1981–85 to about 0.06 mg/L during 2002–04, accounting for more than 50 percent of the observed decrease in total 

phosphorus. A comparison of 1981–85 instantaneous total 

phosphorus loads (median of 0.86 ton per day) with 2002–04 

data (median of 0.46 ton per day) also indicated a significantly 

lower load (p < 0.01) during the later period (fig. 12). 

Total Nitrogen in the Haw River near Bynum

Most total nitrogen data from the USGS for the Haw 

River near Bynum are available for three periods—monthly 

between 1981 and 1985, quarterly or less frequently between 

1992 and 1998, and monthly or biweekly from August 2002 

through August 2004. Monthly total nitrogen data also are 

available from the NCDWQ for January 1980 through 2004. 

As with suspended sediment and total phosphorus, concentrations of total nitrogen from USGS data were significantly 

lower (p < 0.001) using a Mann-Whitney (Conover, 1980) test 

for differences during the later sampling period (median of 

2.2 mg/L compared with a median of 1.4 mg/L). Concentrations of dissolved Kjeldahl nitrogen (organic nitrogen plus 

ammonia) decreased by half from a median concentration of 

1.25 to 0.61 mg/L (p < 0.05) between 1981–85 and 2002–04, 

and accounted for much of the observed decrease in total 

Table 10. Annual phosphorus loads for calendar year 1976–2003 

streamflows in the Haw River near Bynum, North Carolina, for 

two calibration periods, 1981–85 (shaded) and 2002–04 (shaded).

[Annual water-year loads from Childress and Treece (1996) are given for 

comparison] 

Calendar 

year

Phosphorus 

load, 

in tons,

1981–85

Phosphorus 

load, 

in tons,

2002–04

Phosphorus 

load, 

in tons,

from Childress 

and Treece (1996)

1976 324 106

1977 334 112

1978 699 335

1979 798 359

1980 373 145

1981 334 122

1982 682 290

1983 575 235

1984 740 332

1985 558 214

1986 209 68

1987 501 260

1988 264 85

1989 740 305 480

1990 620 238 490

1991 460 189 490

1992 453 167 310

1993 552 251 530

1994 393 163 360

1995 631 265

1996 760 338

1997 434 175

1998 553 280

1999 460 165

2000 409 141

2001 246 98

2002 E 464 162

2003 E 1,054 485

E Calendar year loads for 2002 and 2003 were estimated based on the 

calibration period September 2002 through August 2004.

Figure 12. Instantaneous phosphorus loads for 

1981–85 and 2002–04 at the Haw River near Bynum, 

North Carolina.

22 Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
nitrogen concentrations in the USGS data. Although the 

USGS total nitrogen concentrations appear to have decreased, 

the NCDWQ data did not indicate a corresponding decrease 

in total nitrogen concentrations for the period 1981–2003, 

during which total nitrogen concentrations remained at about 

1.5 mg/L (fig. 13). 

Based on the USGS data, instantaneous total nitrogen 

loads were not significantly different (p > 0.05) between the 

two calibration periods 1981–85 and 2002–04 (median of 

Figure 13. Total nitrogen concentrations from U.S. Geological Survey and North Carolina Division of Water 

Quality databases for the Haw River near Bynum, North Carolina, 1981–2003.

6.6 tons per day compared with a median of 4.2 tons per day, 

p = 0.08), although the variance was significantly lower during 

the later period (1,343 compared with 298). Annual total 

nitrogen loads, however, calculated by the LOADEST program 

using the 2002–04 model were about 40 percent lower than 

loads computed using the 1981–85 model (table 11). Because 

the regression models include flow and seasonal variation, the 

results from the LOADEST program are probably the most 

reliable. 

Historical Changes in Streamflow, Suspended-Sediment, and Nutrient Concentrations and Loads, 1976–2004 23
Streamflow in the Deep River at Moncure

Although the annual median streamflows for the Deep 

River at Moncure, shown in fig. 14, do not indicate a longterm trend, a significant decreasing trend in streamflow was 

detected for the period 1981–2003 using Spearman’s rho on 

daily mean streamflows (ρ = - 0.03, p < 0.05). As indicated 

previously for the Haw River, this change is not considered 

to be a significant factor in controlling water quality or 

explanatory for any observed trend over the past 20–30 years. 

Based on the information presented in figure 14, water-quality 

samples were collected for this investigation at streamflows 

that were among the lowest (2002), similar to those during 

the late 1980s, and the highest (2003) measured for the entire 

period (1980–2004). 

Suspended Sediment in the Deep River at 

Moncure

Between 1976 and 1978, eight suspended-sediment 

samples were collected in the Deep River at Moncure by the 

USGS. Quarterly suspended-sediment samples were collected 

between 1981 and 1983. Because of the relatively few samples 

collected during 1976–83, it is difficult to reliably assess 

trends or changes through time. Statistical comparisons were 

possible, however, using the Mann-Whitney test, and enough 

suspended-sediment data (25 samples) were available to estimate loads using the LOADEST program and the calibrated 

model for two periods, 1976–83 and 2002–04. 

Suspended-sediment concentrations were not significantly lower (p > 0.05) during 2002–04 (median of 12 mg/L) 

compared with concentrations observed during 1976–83 

(median of 23 mg/L). The small sample size (25 samples) and 

large variability for the early period make it difficult to statistically discern a difference. The total suspended-solids data 

collected by the NCDWQ during 1992–97 and 1998–2002 

also do not indicate a significant (p > 0.05) difference in 

concentrations between the two periods. 

The suspended-sediment loads for calendar years 

1976–2003 were computed using a model calibrated with 

the historical dataset (1976–83) and compared with loads 

from a model calibrated with the current dataset (2002–04). 

Using this procedure, much larger loads (about a factor of 2 or 

greater) were calculated for the 1976–83 period than for the 

2002–04 period (table 12). These results are not in agreement 

with results from the two-sample statistical tests; however, 

because the LOADEST model accounts for streamflow 

and concentration and considering that cropland decreased 

between 1980 and 1990 (Appendix 5), it appears likely that 

suspended-sediment loads have decreased somewhat in the 

Deep River since the late 1970s and early 1980s.

Table 11. Annual total nitrogen loads for calendar year 

1976–2003 streamflows in the Haw River near Bynum, North 

Carolina, for two calibration periods, 1981–85 (shaded) and 

2002–04 (shaded).

[Annual water-year loads from Childress and Treece (1996) are given for 

comparison]

Calendar 

year

Total 

nitrogen 

load, 

in tons,

1981–85

Total 

nitrogen 

load, 

in tons, 

2002–04

Total 

nitrogen 

load, 

in tons, 

from Childress 

and Treece (1996)

 1976 1,790 1,118

 1977 1,820 1,133

 1978 4,209 2,476

 1979 4,520 2,659

 1980 2,295 1,395

 1981 1,730 1,089

 1982 3,939 2,308

 1983 3,580 2,095

 1984 4,403 2,573

 1985 2,903 1,742

 1986 1,183 783

 1987 3,218 1,938

 1988 1,467 943

 1989 4,129 2,422 2,800

 1990 3,518 2,065 2,900

 1991 2,785 1,677 2,900

 1992 2,511 1,526 1,800

 1993 3,579 2,110 3,100

 1994 2,418 1,473 2,100

 1995 3,268 1,951

 1996 3,869 2,306

 1997 2,664 1,607

 1998 3,690 2,182

 1999 2,289 1,403

 2000 2,261 1,380

 2001 1,528 972

 2002 E 2,248 1,364

 2003 E 5,968 3,445

E Calendar year loads for 2002 and 2003 were estimated based on the 

calibration period September 2002 through August 2004.

24 Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
Figure 14. Annual streamflow in the Deep River at Moncure, North Carolina, 1976–2004.

Historical Changes in Streamflow, Suspended-Sediment, and Nutrient Concentrations and Loads, 1976–2004 25
Total Phosphorus in the Deep River at Moncure

Sampling for nutrients in the Deep River was conducted 

by the USGS during 1981–83. Total suspended-solids and 

nutrient data are available from the NCDWQ for the period 

1992–2004. Based on the USGS data, total phosphorus 

concentrations in the Deep River were not significantly 

(p > 0.05) different for the period 1981–83 (median of 

0.22 mg/L) than for 2002–04 (median of 0.21 mg/L), and 

total phosphorus concentrations have remained near those 

measured in the early 1980s. No influence related to improvements in wastewater treatment or the ban on phosphorus in 

detergents was evident in the available phosphorus data. As 

indicated previously, the occurrence of continuous discharges 

(from point sources or ground water) of phosphorus upstream 

from this site are the likely source of elevated phosphorus 

concentrations in the Deep River. Nutrient loads for the period 

1981–83 could not be estimated from the USGS data because 

too few samples (< 24) were available for calibration using the 

LOADEST program.

Total Nitrogen in the Deep River at Moncure

As with total phosphorus, total nitrogen concentrations 

were not significantly different (p > 0.05) in the Deep River 

for the period 1981–83 (median of 1.75) than for 2002–04 

(median of 1.5). Data from the NCDWQ also did not significantly (p > 0.05) differ for the two periods 1992–97 (median 

of 1.17) and 1997–2002 (median of 1.11), although these 

data-collection periods do not reflect any changes since the 

late 1970s or early 1980s, which are the focus of this report. 

Although both the USGS and NCDWQ datasets do not 

indicate a significant change through time for either comparison period, total nitrogen concentrations were significantly 

(p < 0.05) higher in the USGS data than in the NCDWQ data, 

indicating that the data are not directly comparable and may 

yield significantly different values for load calculations. 

Summary and Conclusions

Water-quality samples were collected from the Haw 

River near Bynum and the Deep River at Moncure, NC, over a 

2-year period beginning in August 2002 and ending in August 

2004. Regular sampling was conducted at approximately 

1- to 2-week intervals for nutrients and suspended sediment. 

Sampling for nutrients, suspended sediment, major ions, and 

trace elements was conducted during targeted runoff events. 

Samples were collected over a wide range of hydrologic 

conditions during the 2-year sampling period, beginning 

with an extremely dry water year (2002), continuing through 

an extremely wet water year (2003), and ending during a 

more hydrologically normal water year (2004). This range of 

streamflows provides a useful dataset for comparing waterquality characteristics and nutrient and sediment loads in 

Table 12. Annual suspended-sediment loads 

for calendar year 1976–2003 streamflows in the 

Deep River at Moncure, North Carolina, for two 

calibration periods, 1976–83 (shaded) and 2002–04 

(shaded). 

Calendar 

year 

 Suspendedsediment 

load, 

in tons,

1976–84

Suspendedsediment 

load, 

in tons,

2002–04

1976 120,900 50,229

1977 174,031 69,169

1978 354,560 134,469

1979 510,623 188,153

1980 148,588 60,383

1981 77,231 32,188

1982 323,263 126,352

1983 334,818 130,050

1984 539,219 201,398

1985 315,449 118,995

1986 42,755 18,363

1987 243,932 91,609

1988 72,277 30,602

1989 466,355 176,545

1990 247,544 98,553

1991 181,069 71,377

1992 133,334 54,201

1993 348,962 131,104

1994 128,071 51,269

1995 381,169 144,421

1996 294,742 112,914

1997 255,027 98,784

1998 632,064 227,694

1999 187,904 73,529

2000 101,454 42,496

2001 55,928 22,847

2002 E 156,266 62,016

2003 E 538,047 202,519

E Calendar year loads for 2002 and 2003 were estimated 

based on the calibration period September 2002 through 

August 2004.

26 Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
these two major river basins in the Piedmont Physiographic 

Province. 

Based on analysis of the major ion composition, water 

in both the Haw and Deep Rivers is of mixed ionic composition that tends to be dominated by calcium and bicarbonate 

during high flows in the winter and spring and by sodium and 

chloride during low flows in the summer and fall. In general, 

the ionic composition of water in the Haw River near Bynum 

was more variable than in the Deep River at Moncure. Average 

concentrations of suspended sediment and total nitrogen in 

water from both rivers were similar. During the investigation, 

however, total phosphorus concentrations were significantly 

higher in the Deep River (median of 0.21 mg/L) than total 

phosphorus concentrations in the Haw River (median of 

0.13 mg/L), which is indicative that more phosphorus enters 

the Deep River basin through continuous (point-source or 

ground-water) discharges. 

Annual loads were computed for calendar years 2002 and 

2003 using data collected during this investigation. During 

calendar year 2002, the Haw River near Bynum transported 

1,400 tons of total nitrogen, 160 tons of total phosphorus, 

and 56,000 tons of suspended sediment. In 2003, the Haw 

River transported 3,400 tons of total nitrogen, 470 tons of 

total phosphorus, and 230,000 tons of suspended sediment. 

The yields for total nitrogen were 1.1 (tons/yr)/mi2 in 2002 

and 2.7 (tons/yr)/mi2 in 2003. The yields for total phosphorus 

were 0.13 (ton/yr)/mi2 in 2002 and 0.37 (ton/yr)/mi2 in 2003. 

Suspended-sediment yields were 44 (tons/yr)/mi2 in 2002 and 

180 (tons/yr)/mi2 in 2003. The reported annual loads for the 

Haw River were estimated to be generally within 30–50 percent of the actual loads transported.

Loads and yields were consistently higher in the 

Deep River than in the Haw River for total nitrogen, total 

phosphorus, and suspended sediment. The Deep River at 

Moncure transported 1,700 tons of total nitrogen, 260 tons 

of total phosphorus, and 88,000 tons of suspended sediment 

during calendar year 2002. During calendar year 2003 the 

river transported 4,000 tons of total nitrogen, 740 tons of 

total phosphorus, and 380,000 tons of suspended sediment. 

The yields for total nitrogen were 1.2 (tons/yr)/mi2 in 2002 

and 2.8 (tons/yr)/mi2 in 2003. The yields for total phosphorus 

were 0.18 (ton/yr)/mi2 in 2002 and 0.52 (ton/yr)/mi2 in 2003. 

Suspended-sediment yields were 61 (tons/yr)/mi2 in 2002 and 

270 (tons/yr)/mi2 in 2003. 

Loads were also calculated to provide insight on the 

seasonal transport of loads of nutrients and sediment in the 

Haw and Deep Rivers. During this investigation, loads of all 

constituents analyzed were greatest during the spring and summer months of 2003, an extremely wet year, and lowest during 

the fall and winter months. During 2004, a more normal year 

hydrologically, primary transport occurred during the winter 

months. Because water year 2003 was much wetter than water 

year 2004, significantly greater loads during the first four 

seasons were transported than the last four at both sites. The 

largest loads of all constituents sampled during the spring of 

2003 were transported at both sites.

Compared with the Haw River, the Deep River generally had higher yields of sediment and nutrients, particularly 

phosphorus, even though the Deep River basin generally has 

more forested land, less cropland, and less developed land. 

Possible reasons for higher yields in the Deep River than in the 

Haw River include (1) more stringent regulations for dischargers along the Haw River, because it is designated as Nutrient 

Sensitive Water by the NCDWQ; (2) substantially more 

livestock present in the Deep River basin, particularly poultry; 

and (3) more dams located on the Haw River (59) than on the 

Deep River (34). 

Historical streamflow and water-quality data at both 

sites, collected by the USGS and the NCDWQ, were used 

to evaluate historical changes through time and to compare 

information provided by the two datasets. Water-quality 

changes were greatest in the Haw River near Bynum, with a 

definable decrease in suspended-sediment, total nitrogen, and 

total phosphorus concentrations and loads. Loss of cropland 

between 1980 and 1990 and improved land-management 

practices account for the decrease in suspended-sediment 

loads, and improved wastewater-treatment practices in the 

Haw River basin account for the lower nutrient concentrations. 

Because of the small number of nutrient and suspendedsediment samples collected in the Deep River, changes over 

time were not detected using a Mann-Whitney two-sample test 

for suspended sediment, total nitrogen, or total phosphorus. 

A regression model calibrated for the 1981–83 streamflow 

and concentration data, however, yielded hypothetical loads 

twice those calculated using 2002–04 data, indicating that 

suspended-sediment loads have decreased since the early 

1980s in the Deep River. Nutrient concentrations in the Deep 

River, however, have remained relatively unchanged since the 

early 1980s.

References

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Research Triangle area of North Carolina, 1988–94: U.S. 

Geological Survey Water-Resources Investigations Report 

95–4282, 79 p.

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the moments of lognormal populations from type I censored 

samples: U.S. Geological Survey Open-File Report 88–350, 

34 p.

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Conover, W.J., 1980, Practical non-parametric statistics: New 

York, John Wiley and Sons, 493 p.

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land cover mapping for the State of North Carolina­—Final 

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Fishman, M.J., 1993, Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory—

Determination of inorganic and organic constituents in 

water and fluvial sediments: U.S. Geological Survey OpenFile Report 93–125, 217 p.

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

determination of inorganic substances in water and fluvial 

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

Gray, J.R., Glysson, G.D., Turcios, L.M., and Schwarz, G.E., 

2000, Comparability of suspended-sediment concentration 

and total suspended solids data: U.S. Geological Survey 

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North Carolina Department of Environment and Natural 

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CPF%202004%20Report%20Final.pdf

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quality plan; accessed in December 2004 at http://h2o.enr.

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North Carolina Division of Water Quality, 2003, Water quality standards for freshwater classifications, April 1, 2003; 

accessed May 25, 2005, at http://h2o.enr.state.nc.us/csu/

fwtabapr03.pdf

North Carolina Division of Water Quality, 2005a, Basinwide 

planning program—DRAFT March 2005 Cape Fear River 

basinwide water quality plan; accessed on July 28, 2005, at 

http://h2o.enr.state.nc.us/basinwide/draftCPFApril2005.htm

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h2o.enr.state.nc.us/esb/stations/ams.htm

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R., and Blair, R., 1995, Environmental and economic costs 

of soil erosion and conservation benefits: Science, v. 267, 

no. 5201, p. 1117–1123.

Ragland, B.C., Barker, R.G., and Robinson, J.B., 2003, Water 

resources data, North Carolina, water year 2002: U.S. Geological Survey Water-Data Report NC–02–1B, 665 p.

Ragland, B.C., Barker, R.G., and Robinson, J.B., 2004, Water 

resources data, North Carolina, water year 2003: U.S. Geological Survey Water-Data Report NC–03–1B, 796 p.

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of streamflow: v. 1. Measurement of stage and discharge; 

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Water-Supply Paper 2175, 631 p.

Richter, D.D., Korfmacher, K., and Nau, R., 1995, Decreases 

in Yadkin River basin sedimentation—Statistical and geographic time-trend analyses, 1951 to 1990: Raleigh, NC, 

Water Resources Research Institute of The University of 

North Carolina, Report No. 297, 93 p.

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estimator (LOADEST)—A FORTRAN program for 

estimating constituent loads in streams and rivers: 

U.S. Geological Survey Techniques and Methods, book 4, 

chap. A5, 75 p. 

Simmons, C.E., 1993, Sediment characteristics of North 

Carolina streams, 1970–79: U.S. Geological Survey WaterSupply Paper 2364, 84 p.

Simmons, C.E., and Heath, R.C., 1982, Water-quality characteristics of streams in forested and rural areas of North 

Carolina: U.S. Geological Survey Water-Supply Paper 2185, 

chap. B, 33 p.

Smith, R.A., Alexander, R.B., and Lanfear, K.J., 1993, Stream 

water quality in the conterminous United States—Status and 

trends of selected indicators during the 1980’s, in U.S. Geological Survey, 1993, National water summary 1990–91—

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of the association and the upper Cape Fear River basin; 

accessed on May 26, 2005, at http://www.cfra-nc.org/

ucfrba.htm

28 Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
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Technical Publication NA–PR–07–91. 

Appendixes

Appendix 1. Nutrient and suspended-sediment concentrations in water samples 

from the Haw River near Bynum, North Carolina

Appendix 2. Nutrient and suspended-sediment concentrations in water samples 

from the Deep River at Moncure, North Carolina

Appendix 3. Selected major ions and trace element concentrations in water samples 

from (A) the Haw River near Bynum and (B) the Deep River at Moncure, 

North Carolina

Appendix 4. Equations used in load calculations for suspended sediment, total nitrogen, 

and phosphorus in (A) the Haw River near Bynum and (B) the Deep River 

at Moncure, North Carolina

Appendix 5. Planted crop acreage in counties in the upper Cape Fear River basin, 

1980–2004

Appendix 1. Nutrient and suspended-sediment concentrations in water samples from the Haw River near Bynum, North 

Carolina.—Continued

[mg/L, milligrams per liter; N, nitrogen; P, phosphorus; —, no data; <, less than; E, estimated]

 Date Time

Ammonia 

plus organic 

nitrogen, water, 

unfiltered, in 

mg/L as N

Ammonia, 

water, 

filtered, in 

mg/L as N

Nitrite 

plus 

nitrate, 

water, 

filtered, in 

mg/L as N

Nitrite, 

water, 

filtered, in 

mg/L as N

Total 

nitrogen, 

water, 

unfiltered, 

in mg/L 

as N

Orthophosphate, 

water, 

filtered, in 

mg/L as P

Phosphorus, 

water, 

unfiltered, 

in mg/L

Suspended 

sediment, 

in mg/L

8/14/2002 0930 0.97 0.038 0.53 0.007 1.5 0.252 — 6

8/20/2002 0945 1.20 0.056 1.18 0.015 2.3 0.276 — 7

8/27/2002 1300 1.70 0.239 2.17 0.044 3.9 0.462 — 9

9/4/2002 1200 0.72 0.086 0.73 0.010 1.5 0.058 — 17

9/11/2002 1145 0.60 0.016 0.81 0.004 1.4 0.083 — 9

9/17/2002 1030 0.72 0.026 1.00 0.005 1.7 0.089 — 9

9/17/2002 1100 0.74 0.025 1.01 0.005 1.8 0.091 — 7

9/25/2002 1100 1.00 0.036 3.46 0.016 4.5 0.327 — 18

10/1/2002 1145 0.92 0.025 2.72 0.012 3.6 0.255 — 4

10/7/2002 1100 0.83 0.026 3.14 0.016 4.0 0.278 — 5

10/15/2002 1430 0.81 0.095 1.34 0.013 2.1 0.067 — 41

10/22/2002 1330 0.60 0.052 0.84 0.011 1.4 0.056 — 10

10/29/2002 0915 0.89 0.046 1.55 0.013 2.4 0.177 — 46

11/5/2002 1100 0.53 0.020 0.75 0.010 1.3 0.069 — 6

11/12/2002 0900 0.72 0.025 0.63 0.009 1.3 0.080 — 55

11/19/2002 1145 0.67 0.063 0.41 0.009 1.1 0.034 0.11 30

11/26/2002 1000 < 0.1 0.023 0.96 0.011 — 0.044 < 0.04 5

12/3/2002 0845 0.58 < 0.015 1.49 0.007 2.1 0.109 0.15 5

12/9/2002 0930 0.71 0.077 0.73 0.008 1.4 0.058 0.12 12

12/17/2002 0915 0.60 0.064 0.51 0.008 1.1 0.021 0.12 51

1/8/2003 0930 0.40 0.018 0.60 0.008 1.0 0.022 0.07 11

1/14/2003 0915 0.48 0.041 1.10 0.022 1.6 0.035 0.07 7

1/21/2003 0900 0.50 0.018 1.31 0.020 1.8 0.032 0.08 5

1/30/2003 0945 0.65 0.099 1.45 0.042 2.1 0.043 0.08 6

2/5/2003 0915 0.45 0.018 0.63 0.011 1.1 0.015 0.07 8

2/7/2003 1145 0.85 0.249 0.59 0.030 1.4 0.127 0.22 38

2/11/2003 0930 0.50 0.062 0.53 0.012 1.0 0.023 0.08 12

2/21/2003 1200 1.00 0.395 0.92 0.031 1.9 0.039 0.10 18

2/25/2003 0900 0.68 0.039 0.40 0.008 1.1 0.012 0.17 58

3/7/2003 0915 0.69 0.108 0.41 0.014 1.1 0.049 0.15 51

3/21/2003 0845 1.00 0.105 0.22 0.007 1.3 0.024 0.33 218

3/24/2003 1200 0.56 0.039 0.39 0.009 1.0 0.015 0.13 32

4/1/2003 0915 0.64 0.066 0.48 0.016 1.1 0.031 0.13 31

4/8/2003 0930 0.80 0.045 0.30 0.008 1.1 0.039 0.19 137

4/10/2003 1030 0.62 0.056 0.25 0.006 0.9 0.068 0.19 86

4/15/2003 0845 0.73 0.026 0.40 0.007 1.1 0.037 0.09 28

4/22/2003 0915 0.46 0.015 0.71 0.009 1.2 0.035 0.09 19

5/2/2003 1130 0.55 < 0.015 0.57 0.005 1.1 0.049 0.10 9

5/9/2003 1030 0.50 E 0.014 0.98 0.007 1.5 0.088 0.13 5

5/14/2003 0845 0.47 E 0.011 0.69 0.006 1.2 0.073 0.11 6

5/23/2003 1000 0.92 0.048 0.53 0.012 1.5 0.045 0.24 80

5/28/2003 0930 0.55 0.037 0.31 0.009 0.9 0.026 0.07 66

6/2/2003 1100 0.55 E 0.013 0.48 0.007 1.0 0.033 0.11 18

Appendixes  33
Appendix 1. Nutrient and suspended-sediment concentrations in water samples from the Haw River near Bynum, North 

Carolina.—Continued

[mg/L, milligrams per liter; N, nitrogen; P, phosphorus; —, no data; <, less than; E, estimated]

 Date Time

Ammonia 

plus organic 

nitrogen, water, 

unfiltered, in 

mg/L as N

Ammonia, 

water, 

filtered, in 

mg/L as N

Nitrite 

plus 

nitrate, 

water, 

filtered, in 

mg/L as N

Nitrite, 

water, 

filtered, in 

mg/L as N

Total 

nitrogen, 

water, 

unfiltered, 

in mg/L 

as N

Orthophosphate, 

water, 

filtered, in 

mg/L as P

Phosphorus, 

water, 

unfiltered, 

in mg/L

Suspended 

sediment, 

in mg/L

6/13/2003 0930 0.69 0.024 0.52 0.007 1.2 0.075 0.20 52

6/20/2003 0930 0.92 0.036 0.54 0.010 1.5 0.072 0.27 90

6/24/2003 0900 0.61 E 0.009 0.60 0.003 1.2 0.040 0.10 13

7/10/2003 0915 0.48 0.018 1.10 0.007 1.6 0.198 0.27 12

7/14/2003 1230 1.30 0.041 0.33 0.007 1.6 0.029 0.44 237

7/23/2003 0900 0.57 E 0.013 0.80 0.005 1.4 0.080 0.17 352

7/29/2003 1030 0.53 E 0.01 0.54 0.004 1.1 0.080 0.14 8

8/5/2003 0900 0.78 0.032 0.38 0.005 1.2 0.047 0.19 80

8/12/2003 0930 0.62 0.033 0.28 0.005 0.9 0.035 0.11 27

8/27/2003 0845 0.51 < 0.015 0.44 0.004 1.0 0.047 0.11 15

9/3/2003 0915 0.67 0.023 0.43 0.006 1.1 0.051 0.13 27

9/12/2003 0900 0.47 < 0.015 0.75 0.004 1.2 0.041 0.10 10

9/17/2003 0915 0.79 < 0.015 1.12 0.005 1.9 0.093 0.28 177

9/24/2003 0915 1.00 0.043 0.24 0.007 1.3 0.031 0.28 168

10/1/2003 0915 0.52 < 0.015 0.55 E 0.002 1.1 0.062 0.12 12

10/7/2003 0900 0.52 < 0.01 1.20 0.003 1.7 0.198 0.25 6

10/15/2003 1030 0.42 < 0.01 0.67 0.003 1.1 0.082 0.13 11

10/20/2003 1030 0.51 < 0.01 0.74 0.003 1.2 0.069 0.10 3

10/31/2003 1245 0.52 0.023 0.94 0.005 1.5 0.152 0.20 12

11/12/2003 0900 0.45 < 0.01 1.12 0.004 1.6 0.165 0.22 6

11/21/2003 1000 0.54 0.023 1.23 0.005 1.8 0.165 0.23 8

11/28/2003 1100 0.46 E 0.009 0.91 0.003 1.4 0.087 0.13 4

12/11/2003 1330 1.00 0.042 1.18 0.007 2.2 0.075 0.28 77

12/23/2003 1100 0.48 0.044 0.69 0.005 1.2 0.055 0.12 9

1/6/2004 0900 0.41 E 0.005 1.29 0.005 1.7 0.084 0.13 5

1/20/2004 0930 0.53 < 0.01 1.28 0.006 1.8 0.056 0.11 4

2/3/2004 0930 0.55 E 0.007 1.45 0.014 2.0 0.048 0.09 11

2/18/2004 1100 0.48 0.063 0.86 0.015 1.3 0.059 0.12 12

3/8/2004 0915 0.64 0.013 0.76 0.013 1.4 0.063 0.14 22

3/18/2004 0900 0.64 0.038 0.84 0.008 1.5 0.065 0.13 15

3/30/2004 0930 0.56 0.023 0.84 0.006 1.4 0.307 0.37 8

4/13/2004 1000 0.64 0.106 0.97 0.013 1.6 0.152 0.20 17

5/12/2004 1030 0.65 0.035 0.72 0.008 1.4 0.074 0.13 35

5/27/2004 0900 0.57 0.048 1.02 0.010 1.6 0.266 0.33 8

6/10/2004 0915 0.50 0.030 0.83 0.007 1.3 0.099 0.16 20

6/22/2004 0915 0.56 0.041 1.10 0.010 1.7 0.103 0.17 16

7/9/2004 0930 0.54 0.094 0.56 0.006 1.1 0.060 0.11 12

7/15/2004 0945 0.50 0.029 1.03 0.007 1.5 0.100 0.14 9

7/20/2004 0930 0.64 0.141 1.33 0.015 2.0 0.102 0.17 28

7/27/2004 1415 0.60 0.025 0.94 0.005 1.5 0.095 0.14 8

7/30/2004 1015 0.94 0.080 2.77 0.017 3.7 0.138 0.28 69

8/3/2004 0945 0.62 0.024 0.63 0.006 1.2 0.060 0.15 26

8/6/2004 1015 0.58 0.035 0.75 0.006 1.3 0.066 0.14 15

8/15/2004 0845 0.82 0.079 2.01 0.013 2.8 0.090 0.21 51

34 Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
Appendix 2. Nutrient and suspended-sediment concentrations in water samples from the Deep River at Moncure, North 

Carolina.—Continued

[mg/L, milligrams per liter; N, nitrogen; P, phosphorus; —, no data; E, estimated; <, less than]

Date Time

Ammonia 

plus organic 

nitrogen, water, 

unfiltered, in 

mg/L as N

Ammonia, 

water, 

filtered, in 

mg/L as N

Nitrite 

plus nitrate, 

water, 

filtered, in 

mg/L as N

Nitrite, 

water, 

filtered, in 

mg/L as N

Total 

nitrogen, 

water, 

unfiltered, 

in mg/L 

as N

Orthophosphate, 

water, 

filtered, in 

mg/L as P

Phosphorus, 

water, 

unfiltered, 

in mg/L

Suspended 

sediment, 

in mg/L

8/14/2002 1300 0.63 0.018 0.18 0.005 0.8 0.568 — 1

8/20/2002 1345 0.68 0.020 0.47 0.009 1.1 0.704 — 4

8/27/2002 0930 0.81 0.072 0.34 0.011 1.1 0.806 — 18

9/4/2002 1530 0.96 0.134 1.14 0.018 2.1 0.149 — 18

9/11/2002 0945 0.79 0.049 2.14 0.028 2.9 0.47 — 6

9/17/2002 1230 0.68 0.023 0.91 0.009 1.6 0.202 — 17

9/25/2002 0845 0.62 0.023 0.67 0.006 1.3 0.213 — 28

10/1/2002 0915 0.60 0.019 1.82 0.011 2.4 0.518 — 6

10/7/2002 1315 0.55 0.016 0.92 0.007 1.5 0.389 — 2

10/12/2002 1130 2.70 0.155 1.20 0.020 3.9 0.138 — 468

10/15/2002 1130 1.20 0.184 1.09 0.022 2.3 0.128 — 27

10/22/2002 1030 0.70 0.057 0.86 0.011 1.6 0.124 — 20

10/29/2002 1115 0.64 0.019 1.22 0.009 1.9 0.159 — 10

11/5/2002 0915 0.90 0.021 0.93 0.009 1.8 0.152 — 7

11/12/2002 1030 0.75 0.022 1.08 0.013 1.8 0.151 — 8

11/19/2002 1330 0.91 0.032 0.59 0.007 1.5 0.118 0.22 38

11/26/2002 1115 0.53 E 0.014 0.88 0.005 1.4 0.096 0.13 4

12/3/2002 1030 0.48 E 0.011 1.15 0.004 1.6 0.129 0.17 4

12/9/2002 1100 0.80 0.045 0.91 0.006 1.7 0.1 0.17 17

12/17/2002 1100 0.63 0.047 0.72 0.006 1.4 0.072 0.15 19

1/8/2003 1100 0.50 0.040 0.79 0.010 1.3 0.112 0.18 9

1/14/2003 1045 0.39 0.028 0.99 0.011 1.4 0.1 0.14 6

1/21/2003 1030 0.33 E 0.012 1.17 0.005 1.5 0.092 0.12 3

1/30/2003 1130 0.35 E 0.011 1.73 0.011 2.1 0.216 0.25 4

2/5/2003 1115 0.75 0.301 0.96 0.015 1.7 0.109 0.16 15

2/11/2003 1100 0.52 0.050 0.69 0.012 1.2 0.053 0.12 16

2/21/2003 1000 0.60 0.051 0.74 0.008 1.3 0.09 0.17 18

2/25/2003 1030 0.82 0.094 0.57 0.009 1.4 0.048 0.19 66

3/6/2003 1445 1.00 0.029 0.46 0.006 1.5 0.07 0.30 205

3/21/2003 1030 1.70 0.096 0.39 0.008 2.0 0.128 0.54 309

3/24/2003 0945 0.70 0.074 0.35 0.008 1.1 0.048 0.16 45

4/1/2003 1030 1.30 0.058 0.64 0.009 1.9 0.086 0.19 31

4/8/2003 1115 0.81 0.050 0.46 0.006 1.3 0.064 0.21 91

4/10/2003 1145 1.00 0.070 0.33 0.006 1.4 0.116 0.30 125

4/15/2003 1015 0.70 0.113 0.39 0.008 1.1 0.051 0.12 148

4/22/2003 1115 0.39 0.022 0.66 0.004 1.1 0.055 0.08 9

5/2/2003 0945 0.44 < 0.015 0.86 0.006 1.3 0.095 0.13 4

5/9/2003 0900 0.85 0.071 0.58 0.012 1.4 0.111 0.19 20

5/14/2003 1300 0.55 E 0.008 0.81 0.009 1.4 0.137 0.18 20

5/28/2003 1100 0.77 0.045 0.47 0.012 1.2 0.095 0.21 61

6/2/2003 0945 0.65 0.019 0.57 0.008 1.2 0.079 0.18 31

6/13/2003 1100 0.68 0.020 0.53 0.008 1.2 0.134 0.22 30

6/20/2003 1100 1.10 0.062 0.51 0.011 1.6 0.108 0.31 120

Appendixes  35
Appendix 2. Nutrient and suspended-sediment concentrations in water samples from the Deep River at Moncure, North 

Carolina.—Continued

[mg/L, milligrams per liter; N, nitrogen; P, phosphorus; —, no data; E, estimated; <, less than]

Date Time

Ammonia 

plus organic 

nitrogen, water, 

unfiltered, in 

mg/L as N

Ammonia, 

water, 

filtered, in 

mg/L as N

Nitrite 

plus nitrate, 

water, 

filtered, in 

mg/L as N

Nitrite, 

water, 

filtered, in 

mg/L as N

Total 

nitrogen, 

water, 

unfiltered, 

in mg/L 

as N

Orthophosphate, 

water, 

filtered, in 

mg/L as P

Phosphorus, 

water, 

unfiltered, 

in mg/L

Suspended 

sediment, 

in mg/L

6/24/2003 1030 0.71 0.019 0.78 0.009 1.5 0.154 0.24 12

7/3/2003 0915 1.10 0.058 0.58 0.010 1.7 0.162 0.41 197

7/10/2003 1045 0.55 < 0.015 0.78 0.005 1.3 0.156 0.23 9

7/16/2003 1000 0.58 0.015 0.80 0.004 1.4 0.103 0.18 27

7/23/2003 1030 0.59 0.016 0.88 0.005 1.5 0.143 0.21 15

7/29/2003 1130 0.61 < 0.015 1.30 0.006 1.9 0.163 0.26 12

8/5/2003 1030 0.88 0.060 0.46 0.009 1.3 0.125 0.27 53

8/27/2003 1015 0.51 < 0.015 0.70 0.003 1.2 0.114 0.19 10

9/3/2003 1045 0.62 0.029 1.19 0.010 1.8 0.119 0.23 40

9/12/2003 1045 0.57 < 0.015 0.72 0.004 1.3 0.156 0.24 17

9/17/2003 1030 0.51 < 0.015 0.81 0.004 1.3 0.14 0.23 10

9/24/2003 1030 1.20 < 0.015 0.53 0.004 1.7 0.098 0.41 195

10/1/2003 1100 0.61 < 0.015 0.58 0.004 1.2 0.126 0.23 41

10/7/2003 1030 0.50 < 0.01 0.79 0.004 1.3 0.133 0.21 6

10/15/2003 1200 0.34 E 0.007 0.91 0.004 1.3 0.096 0.15 6

10/20/2003 1200 0.47 E 0.007 1.18 0.004 1.6 0.149 0.20 7

10/31/2003 1430 0.45 E 0.009 0.82 0.004 1.3 0.074 0.11 13

11/12/2003 1030 0.45 < 0.01 0.88 0.003 1.3 0.137 0.19 6

11/21/2003 1200 0.47 E 0.005 0.95 0.003 1.4 0.109 0.18 9

11/28/2003 1215 0.44 < 0.01 1.58 0.004 2.0 0.241 0.33 10

12/11/2003 1500 1.60 0.099 1.27 0.011 2.9 0.168 0.46 162

12/23/2003 1230 0.54 0.022 1.07 0.006 1.6 0.091 0.16 10

1/6/2004 1045 0.31 E 0.009 1.23 0.002 1.5 0.091 0.14 7

1/20/2004 1100 0.36 < 0.01 1.08 0.002 1.4 0.071 0.13 9

2/3/2004 1100 0.36 < 0.01 1.12 0.002 1.5 0.051 0.09 5

2/18/2004 1300 0.52 0.034 0.79 0.007 1.3 0.06 0.12 16

3/8/2004 1045 0.49 0.022 0.80 0.008 1.3 0.084 0.15 10

3/18/2004 1100 0.74 0.040 0.79 0.007 1.5 0.057 0.14 32

3/30/2004 1100 0.38 < 0.01 0.64 0.003 1.0 0.068 0.12 8

4/13/2004 1200 0.43 0.026 0.55 0.003 1.0 0.076 0.11 10

5/12/2004 1145 0.60 0.024 1.07 0.011 1.7 0.133 0.21 12

5/27/2004 1030 0.42 0.027 0.71 0.008 1.1 0.136 0.21 9

6/10/2004 1115 0.57 0.024 1.52 0.011 2.1 0.231 0.31 12

6/22/2004 1045 0.50 0.019 1.40 0.006 1.9 0.351 0.40 8

7/9/2004 1115 0.60 0.013 1.26 0.006 1.9 0.198 0.26 12

7/15/2004 1115 0.60 0.021 1.01 0.008 1.6 0.236 0.31 8

7/20/2004 1115 0.59 0.012 1.03 0.005 1.6 0.316 0.39 23

7/27/2004 1530 0.57 0.022 1.40 0.009 2.0 0.334 0.39 5

7/30/2004 1130 0.68 0.039 1.96 0.014 2.6 0.354 0.43 19

8/3/2004 1045 0.58 0.022 0.82 0.006 1.4 0.223 0.29 9

8/6/2004 1130 0.73 0.026 1.61 0.015 2.3 0.244 0.33 9

8/10/2004 1015 0.58 0.027 1.68 0.009 2.3 0.304 0.35 2

8/15/2004 0945 1.40 0.405 0.81 0.014 2.2 0.205 0.33 57

36 Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
Appendix 3A. Selected major ions and trace element concentrations in water samples from the Haw River near Bynum, North Carolina.

[mg/L, milligrams per liter: μg/L, micrograms per liter; E, estimated; <, less than; water-quality standards (North Carolina Division of Water Quality, 2003) for freshwater in North Carolina for aquatic life (AL), human health (HH), and water supply (WS) are in milligrams per liter unless otherwise noted: for chloride, AL = 230, WS = 250; for sulfate, WS = 250; for arsenic, AL = 50, HH = 10, WS = 10; for cadmium, AL = 2 μg/L; for chromium, AL = 50 μg/L; for copper, AL = 7 μg/L; for iron, AL = 1,000 μg/L; for lead, AL = 25 μg/L; for manganese, WS = 200 μg/L; for mercury, AL = 25 μg/L; for nickel, AL = 88 μg/L, WS = 25 μg/L] 

Date Time

Calcium, 

water, 

filtered, 

in mg/L

Magnesium, 

water, 

filtered, 

in mg/L

Sodium, 

water, 

filtered, 

in mg/L

Chloride, 

water, 

filtered, 

in mg/L

Sulfate, 

water, 

filtered, 

in mg/L

Aluminum, 

water, 

filtered, 

in μg/L

Arsenic, 

water, 

filtered, 

in μg/L

Cadmium 

water, 

filtered, 

in μg/L

Chromium, 

water, 

filtered, 

in μg/L

Copper, 

water, 

filtered, 

in μg/L

 Iron, 

water, 

filtered, 

in μg/L

Lead, 

water, 

filtered, 

in μg/L

Manganese, 

water, 

filtered, 

in μg/L

Mercury, 

water, 

filtered, 

in μg/L

Nickel, 

water, 

filtered, 

in μg/L

2/7/203 1145 6.96 2.9 12.7 10.2 13.3 52 E 0.2 E 0.03 < 0.8 1.7 240 0.16 42.5 < 0.02 1.28

3/21/203 0845 3.83 1.71 3.14 3.84 6.1 77 0.4 < 0.04 < 0.8 1.8 303 0.25 138 < 0.02 0.734/10/203 1030 4.15 1.79 3.09 2.77 5.6 96 0.3 < 0.04 E 0.4 2.1 267 0.15 39.9 < 0.02 0.735/23/203 1000 5.99 2.48 5.1 5.06 6.8 32 0.3 < 0.04 < 0.8 2.6 218 0.14 21.3 < 0.02 1.027/14/203 1230 4.93 1.98 4.47 3.78 5.2 19 0.5 < 0.04 < 0.8 2.1 160 0.11 36.4 < 0.02 0.857/20/204 0930 5.6 2.26 21.9 11.6 19.2 12 0.5 0.09 < 0.8 2.3 79 0.18 15.2 < 0.02 2.097/27/204 1415 7.2 3.58 21.5 18.3 16.7 13 0.5 0.04 < 0.8 2.1 175 0.15 56.5 < 0.02 1.467/30/204 1015 9.3 3.31 40.8 23.7 28.5 10 0.5 0.24 E 0.5 3 101 0.2 29.4 < 0.02 2.87

8/3/204 0945 6.77 2.77 12.4 10.4 9.99 9.1 0.4 E 0.04 < 0.8 2.4 141 0.12 28.7 < 0.02 1.12

8/15/204 0945 8.54 3.1 31.1 21.3 26.2 23.7 0.6 0.34 < 0.8 3.5 181 0.41 25.7 < 0.02 3.19

Appendixes  37
Appendix 3B. Selected major ions and trace element concentrations in water samples from the Deep River at Moncure, North Carolina.

[mg/L, milligrams per liter: μg/L, micrograms per liter; E, estimated; <, less than; water-quality standards (North Carolina Division of Water Quality, 2003) for freshwater in North Carolina for aquatic life (AL), human health (HH), and water supply (WS) are in milligrams per liter unless otherwise noted: for chloride, AL = 230, WS = 250; for sulfate, WS = 250; for arsenic, AL = 50, HH = 10, WS = 10; for cadmium, AL = 2 μg/L; for chromium, AL = 50 μg/L; for copper, AL = 7 μg/L; for iron, AL = 1,000 μg/L; for lead, AL = 25 μg/L; for manganese, WS = 200 μg/L; for mercury, AL = 25 μg/L; for nickel, AL = 88 μg/L, WS = 25 μg/L]

Data Time

Calcium, 

water, 

filtered, 

in mg/L

Magnesium, 

water, 

filtered, 

in mg/L

Sodium, 

water, 

filtered, 

in mg/L

Chloride, 

water, 

filtered, 

in mg/L

Sulfate, 

water, 

filtered, 

in mg/L

Aluminum, 

water, 

filtered, 

in μg/L

Arsenic, 

water, 

filtered, 

in μg/L

Cadmium 

water, 

filtered, 

in μg/L

Chromium, 

water, 

filtered, 

in μg/L

Copper, 

water, 

filtered, 

in μg/L

 Iron, 

water, 

filtered, 

in μg/L

Lead, 

water, 

filtered, 

in μg/L

Manganese, 

water, 

filtered, 

in μg/L

Mercury, 

water, 

filtered, 

in μg/L

Nickel, 

water, 

filtered, 

in μg/L

10/12/02 1130 4.79 1.72 5.08 6.09 6.8 93 1.1 < 0.04 < 0.8 4.4 409 0.24 94.5 < 0.02 1.18

3/6/03 1445 3.94 1.77 4.28 4.71 5.9 134 0.3 < 0.04 < 0.8 2 198 0.11 34 < 0.02 0.69

3/21/03 1030 3.82 1.53 3 3.31 4.8 164 0.6 < 0.04 < 0.8 3.6 437 0.25 42.2 < 0.02 0.76

4/10/03 1145 3.86 1.62 2.95 3.17 5 100 0.5 E 0.03 < 0.8 3.4 222 0.15 18.6 E 0.01 0.86

7/3/03 0915 6.14 2.47 5.69 7.55 5.3 40 0.8 < 0.04 < 0.8 3.4 293 0.33 11.1 < 0.02 0.99

7/20/04 1115 8.55 4.07 16.6 16 13.6 19 1 < 0.04 < 0.8 2.5 276 0.12 76.2 < 0.02 1.22

7/27/04 1530 9.97 5.14 20.3 22.5 16.7 11 1 E 0.02 E 0.6 2.2 186 E 0.08 58.7 < 0.02 1.4

7/30/04 1130 10.9 4.62 24.6 27.2 19.5 7.1 0.9 E 0.02 < 0.8 2.5 97.5 E 0.06 48.1 < 0.02 1.54

8/3/04 1045 7.76 3.32 11.7 13.2 9.9 13 0.9 E 0.02 < 0.8 2.3 228 0.1 47.9 < 0.02 0.94

8/15/04 0945 7.12 2.78 8.46 10.1 9.16 51.5 1 < 0.04 < 0.8 3.6 415 0.19 2.78 < 0.02 1.21

38 Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
Appendix 4. Equations used in load calculations for suspended sediment, total nitrogen, and phosphorus in (A) the Haw River near Bynum 

and (B) the Deep River at Moncure, North Carolina.

A. Haw River equationsNitrogen, ammonia, dissolved (-2.337) + (1.205) lnQ + (0.090) lnQ2Nitrogen, nitrite, dissolved (-3.542) + (0.926) lnQ + (0.011) lnQ2 + (0.318) sin(2�dtime) + (0.065) cos(2�dtime) + (-0.298) dtime

Nitrogen, ammonia + organic, total (0.729) + (1.065) lnQ + (0.063) lnQ2 + (-0.074) sin(2�dtime) + (-0.070) cos(2�dtime)

Nitrogen, NO2 + NO3, dissolved (1.036) + (0.709) lnQ + (-0.031) lnQ2Orthophosphate, dissolved (-1.554) + (0.712) lnQ + (0.0723) lnQ2 + (-0.197) sin(2�dtime) + (-0.099) cos(2�dtime) + (0.195) dtimeTotal phosphorus (-0.275) + (1.138) lnQ + (0.067) lnQ2 + (-0.127) sin(2�dtime) + (-0.145) cos(2�dtime)

Total nitrogen (1.614) + (0.885) lnQ + (0.032) lnQ2

Suspended sediment (4.171) + (1.712) lnQ + (0.065) lnQ2 + (-0.271) sin(2�dtime) + (-0.369) cos(2�dtime)Total phosphorus 1981–85 (-0.371) + (0.970) lnQ + (-0.359) sin(2�dtime) + (-0.074) cos(2�dtime)Total nitrogen 1981–85 (1.339) + (0.982) lnQSuspended sediment 1976–89 (3.894) + (1.822) lnQ + (0.084) lnQ2 + (-0.388) sin(2�dtime) + (-0.499) cos(2�dtime) + (0.050) dtime

B. Deep River equationsNitrogen, ammonia, dissolved (-3.238) + (1.245) lnQ + (0.108) lnQ2Nitrogen, nitrite, dissolved (-4.301) + (1.027) lnQ + (0.011) lnQ2 + (-0.001) sin(2�dtime) + (-0.253) cos(2�dtime) + (-0.326) dtimeNitrogen, ammonia + organic, total (0.117) + (1.174) lnQ + (0.051) lnQ2 + (-0.188) sin(2�dtime) + (-0.142) cos(2�dtime) + (-0.078) dtimeNitrogen, NO2 + NO3, dissolved (0.650) + (0.922) lnQ + (-0.045) lnQ2 + (-0.166) sin(2�dtime) + (0.152) cos(2�dtime) + (0.213) dtime

Orthophosphate, dissolved (-1.453) + (0.796) lnQ + (0.067) lnQ2 + (-0.261) sin(2�dtime) + (-0.239) cos(2�dtime)Total phosphorus (-0.440) + (1.016) lnQ + (0.138) lnQ2Total nitrogen (1.139) + (1.039) lnQ + (-0.152) sin(2�dtime) + (0.001) cos(2�dtime)Suspended sediment (3.153) + (1.695) lnQ + (0.114) lnQ2 + (-0.267) sin(2�dtime) + (-0.326) cos(2�dtime)Suspended sediment 1976–84 (3.793) + (1.654) lnQSuspended sediment 2002–04 (3.464) + (1.61) lnQ

Appendixes  39
Appendix 5. Planted crop acreage in counties in the upper Cape Fear River basin, 1980–2004.

[Data are from the U.S. Department of Agriculture (2004)]

40 Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–2004
Prepared by:

U.S. Geological Survey

Enterprise Publishing Network

North Carolina Water Science Center

3916 Sunset Ridge Road

Raleigh, NC 27607

A PDF version of this publication is available online at URL 

	 http://pubs.water.usgs.gov/sir2005-5271/
Spruill and others—Suspended Sediment and Nutrients in the Upper Cape Fear River Basin, North Carolina, 2002–04,

 with an Analysis of Temporal Changes, 1976–2004 

USGS SIR 2005–5271

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