U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2010–5151

Prepared in cooperation with the

New Jersey Department of Environmental Protection

Relation of Water Quality to Land Use in the Drainage 

Basins of Six Tributaries to the Lower Delaware River, 

New Jersey, 2002–07
Cover: Receding stormwater left a large log straddling the foot bridge at the Cooper River near Haddonfield, 

New Jersey (photograph by Ronald J. Baker, July 14, 2004, U.S. Geological Survey)
Relation of Water Quality to Land Use in 

the Drainage Basins of Six Tributaries to 

the Lower Delaware River, New Jersey, 

2002–07

By Ronald J. Baker and Rachel A. Esralew

Prepared in cooperation with the

New Jersey Department of Environmental Protection

Scientific Investigations Report 2010–5151

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2010

For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, 

natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGS

For an overview of USGS information products, including maps, imagery, and publications, 

visit http://www.usgs.gov/pubprod

To order this and other USGS information products, visit http://store.usgs.gov

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Baker, R.J., and Esralew, R.A., 2010, Relation of water quality to land use in the drainage basins of six tributaries to 

the lower Delaware River, New Jersey, 2002–07: U.S. Geological Survey Scientific Investigations Report 2010–5151, 

68 p.
iii

Contents

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

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

Purpose and Scope ..............................................................................................................................3

Previous Investigations........................................................................................................................3

Study Area..............................................................................................................................................5

Methods of Study...........................................................................................................................................7

Site Selection.........................................................................................................................................8

Data Collection....................................................................................................................................16

Water-Quality and Streamflow Data.......................................................................................16

Determination of Yields.............................................................................................................17

Data Evaluation ...................................................................................................................................17

Hydrologic Data..........................................................................................................................17

Discharge Hydrograph Extension and Base-Flow Separation .................................19

Water-Quality Data....................................................................................................................21

Statistical Methods ...................................................................................................................21

Relations of Water Quality to Streamflow, Season, and Land Development.....................................23

Water-Quality Data.............................................................................................................................23

Nitrogen.......................................................................................................................................23

Total Nitrogen ....................................................................................................................23

Nitrite Plus Nitrate............................................................................................................26

Ammonia.............................................................................................................................31

Organic Nitrogen ..............................................................................................................31

Phosphorus.................................................................................................................................31

Total Phosphorus ..............................................................................................................36

Orthophosphate ................................................................................................................36

Ratios of Total Nitrogen to Total Phosphorus........................................................................36

Bacteria.......................................................................................................................................41

Total Suspended Solids.............................................................................................................43

Estimated Annual Yields of Total Nitrogen and Total Phosphorus..............................................43

Summary and Conclusions.........................................................................................................................49

References Cited..........................................................................................................................................49

Appendix 1. Summary statistics for concentrations and yields of selected constituents, by 

base flow, stormflow, growing season, and nongrowing season, in samples from six 

streams in the lower Delaware River Basin, New Jersey, years 2002–07 ...........................53
iv

Figures

1-8. Maps showing—

1. Delaware Bay and the upper, middle, and lower zones of the lower 

Delaware River.....................................................................................................................4

2. Locations of water-quality monitoring sites and subbasins in the lower 

Delaware River Basin Watershed in New Jersey .........................................................6

3. Land use in site AGR1 drainage basin, lower Delaware River Basin in 

New Jersey...........................................................................................................................9

4. Land use in site AGR2 drainage basin, lower Delaware River Basin in 

New Jersey.........................................................................................................................11

5. Land use in site UND1 drainage basin, lower Delaware River Basin in 

New Jersey.........................................................................................................................12

6. Land use in site UND2 drainage basin, lower Delaware River basin in 

New Jersey.........................................................................................................................13

7. Land use in site URB1 drainage basin, lower Delaware River watershed in 

New Jersey.........................................................................................................................14

8. Land use in site URB2 drainage basin, lower Delaware River Basin in 

New Jersey.........................................................................................................................15

9-10. Graphs showing—

9. Example of a rating curve used for determining streamflow from measured 

stream stage for site UND2, Gravelly Run at Laurel Lake, New Jersey ...................19

10. Example of a stream-stage hydrograph which includes automatic and manual 

stream-stage measuements for URB2, South Branch Big Timber Creek 

Tributary at Grenloch, New Jersey, October 17–18, 2006 ...........................................20

11-26. Boxplots showing—

11. Distributions of total nitrogen concentrations in unfiltered water samples 

collected during base flow and stormflow in the growing and nongrowing 

seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 

2002–06 ................................................................................................................................27

12. Distributions of area-normalized loads (yields) of total nitrogen in unfiltered 

water samples collected during base flow and stormflow in the growing and 

nongrowing seasons at monitoring sites in the lower Delaware River Basin, 

New Jersey, 2002–06.........................................................................................................28

13. Distributions of nitrate concentrations in unfiltered water samples collected 

during base flow and stormflow in the growing and nongrowing seasons at 

monitoring sites in the lower Delaware River Basin, New Jersey, 2002–06 ...........29

14. Distributions of area-normalized loads (yields) of nitrate in unfiltered water 

samples collected during base flow and stormflow in the growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, 

New Jersey, 2002–06.........................................................................................................30

15. Distributions of ammonia concentrations in unfiltered water samples 

collected during base flow and stormflow in the growing and nongrowing 

seasons at monitoring sites in the lower Delaware River Basin, 

New Jersey, 2002–06.........................................................................................................32

16. Distributions of area-normalized loads (yields) of ammonia in unfiltered water 

samples collected during base flow and stormflow in the growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, 

New Jersey, 2002–06.........................................................................................................33
v

17. Distributions of organic nitrogen concentrations in unfiltered water samples 

collected during base flow and stormflow in the growing and nongrowing 

seasons at monitoring sites in the lower Delaware River Basin, 

New Jersey, 2002–06.........................................................................................................34

18. Distributions of area-normalized loads (yields) of organic nitrogen in unfiltered water samples collected during base flow and stormflow in the 

growing and nongrowing seasons at monitoring sites in the lower 

Delaware River Basin, New Jersey, 2002–06................................................................35

19. Distributions of total phosphorus concentrations in unfiltered water samples 

collected during base flow and stormflow in the growing and nongrowing 

seasons at monitoring sites in the lower Delaware River Basin, 

New Jersey, 2002–06.........................................................................................................37

20. Distributions of area-normalized loads (yields) of total phosphorus in unfiltered water samples collected during base flow and stormflow in the 

growing and nongrowing seasons at monitoring sites in the lower 

Delaware River Basin, New Jersey, 2002–06................................................................38

21. Distributions of orthophosphate concentrations in unfiltered water samples 

collected during base flow and stormflow in the growing and nongrowing 

seasons at monitoring sites in the lower Delaware River Basin, 

New Jersey, 2002–06.........................................................................................................39

22. Distributions of area-normalized loads (yields) of orthophosphate in unfiltered water samples collected during base flow and stormflow in the 

growing and nongrowing seasons at monitoring sites in the lower 

Delaware River Basin, New Jersey, 2002–06................................................................40

23. Distributions of fecal coliform bacteria concentrations in unfiltered water 

samples collected during base flow and stormflow in the growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, 

New Jersey, 2002–06.........................................................................................................42

24. Distributions of area-normalized loads (yields) of fecal coliform bacteria in 

unfiltered water samples collected during base flow and stormflow in the 

growing and nongrowing seasons at monitoring sites in the lower 

Delaware River Basin, New Jersey, 2002–06................................................................44

25. Distributions of total suspended solids concentrations in unfiltered water 

samples collected during base flow and stormflow in the growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, 

New Jersey, 2002–06.........................................................................................................45

26. Distributions of area-normalized loads (yields) of total suspended solids in 

unfiltered water samples collected during base flow and stormflow in the 

growing and nongrowing seasons at monitoring sites in the lower 

Delaware River Basin, New Jersey, 2002–06................................................................46

27. Graph showing yields of phosphorus and nitrogen nutrient species in six streams 

in the lower Delaware River Basin, New Jersey, 2002.........................................................48
vi

Tables

1. Mean annual values of total phosphorus , total nitrogen, chlorophyll-a, and water 

clarity as determined with using a Secchi disk for five trophic states................................2

2. Locations of six sites in the lower Delaware River Basin, New Jersey, at which streamflow and water quality were monitored during eight storms from 

2002 to 2007....................................................................................................................................7

3. Area of, and land-use distribution in 2002 in, drainage basins upstream from six 

sites in the lower Delaware River Basin, New Jersey, at which streamflow and 

water quality were monitored during eight storms during 2002–07.....................................7

4. Description of monitoring events at six sites on streams in the lower Delaware 

River Basin, New Jersey, 2003–07 .............................................................................................8

5. Reference sites used to determine the number of days between the end of a storm 

and the return to stream base flow for six streams in the lower Delaware River 

Basin, New Jersey .....................................................................................................................17

6. Analytical methods used for surface-water samples ..........................................................18

7. Results of statistical tests to determine whether constituent concentrations and 

yields differ among sites during growing and nongrowing seasons, lower 

Delaware River Basin, New Jersey.........................................................................................24

8. Mean percentages of total nitrogen in unfiltered water samples represented by 

four nitrogen species for six streams in the lower Delaware River Basin, 

New Jersey..................................................................................................................................26

9. Ratios of nitrogen to phosphorus in six tributaries to the Delaware River, 

New Jersey, 2003–07 ...............................................................................................................41

10. Annual loads of selected water-quality characteristics for three streams in the 

lower Delaware River Basin, New Jersey .............................................................................47
vii

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2

) 2.590 square kilometer (km2) 

Flow rate

foot per second (ft/s) 0.3048 meter per second (m/s)

cubic foot per second (ft3

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

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

°F=(1.8×°C)+32

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

°C=(°F-32)/1.8

Specific conductance is given 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).

Abstract

Concentrations and loads of water-quality constituents 

in six streams in the lower Delaware River Basin of New 

Jersey were determined in a multi-year study conducted by 

the U.S. Geological Survey, in cooperation with the New 

Jersey Department of Environmental Protection. Two streams 

receive water from relatively undeveloped basins, two from 

largely agricultural basins, and two from heavily urbanized 

basins. Each stream was monitored during eight storms and 

at least eight times during base flow during 2002–07. Sampling was conducted during base flow before each storm, 

when stage was first observed to rise, and several times during 

the rising limb of the hydrographs. Agricultural and urban 

land use has resulted in statistically significant increases in 

loads of nitrogen and phosphorus species relative to loads in 

undeveloped basins. For example, during the growing season, 

median storm flow concentrations of total nitrogen in the two 

streams in agricultural areas were 6,290 and 1,760 mg/L, 

compared to 988 and 823 mg/L for streams in urban areas, and 

719 and 333 mg/L in undeveloped areas. Although nutrient 

concentrations and loads were clearly related to land use—

urban, agricultural, and undeveloped— within the drainage 

basins, other basin characteristics were found to be important. 

Residual nutrients entrapped in lake sediments from streams 

that received effluent from recently removed sewage-treatment 

plants are hypothesized to be the cause of extremely high 

levels of nutrient loads to one urban stream, whereas another 

urban stream with similar land-use percentages (but without 

the legacy of sewage-treatment plants) had much lower levels 

of nutrients. One of the two agricultural streams studied had 

higher nutrient loads than the other, especially for total phosphorous and organic nitrogen. This difference appears to be 

related to the presence (or absence) of livestock (cattle).

Introduction

The ecologically significant effect of excess nutrients in 

a water body is eutrophication, which stimulates an array of 

changes. These changes can include increased phytoplankton 

and rooted aquatic plant (macrophyte) production, deterioration of fish habitat and water quality, a decrease in biodiversity, and other undesirable changes that interfere with water 

uses (Bartsch, 1972). Biodiversity tends to decrease with 

increasing eutrophication (Weckström and others, 2007). 

The trophic state of a water body can be characterized by the 

concentration of phosphorus, nitrogen, chlorophyll a, and dissolved oxygen and by water clarity as determined by a Secchi 

disk or other means. The ranges of those nutrient and chlorophyll-a concentrations and water-clarity levels that correspond 

to various trophic states are listed in table 1.

Naturally occurring eutrophication is the natural aging 

process of a water body and the subsequent effects on water 

quality and biological structure and function (Rast and 

Thornton, 1996). External or allochthonous sediment and 

organic matter of terrestrial origin accumulate in a lake basin, 

gradually decreasing the depth of the water body and allowing 

autochthonous biologic production to increase to the point that 

the lake begins to take on a marsh-like character and, ultimately, a terrestrial character. The same progression occurs in 

wide, slow-flowing reaches of streams, resulting in the filling 

of the stream or river valley as the end point. Natural eutrophication generally occurs over geologic time, whereas anthropogenic or “cultural” eutrophication can occur within a decade.

Although the lower reaches of the Delaware River are 

not substantially eutrophic, the middle and upper reaches have 

high nutrient and chlorophyll a concentrations and moderately 

low dissolved oxygen concentrations (Delaware Inland Bays 

Estuary Program, 1993). Contributions of organic, inorganic, 

and microbial contaminants from the lower Delaware River 

Basin can have adverse effects on the ecological, commercial, 

and recreational value of the estuary and the Delaware Bay. 

The Delaware Estuary receives some of the largest loads of 

Relation of Water Quality to Land Use in the Drainage 

Basins of Six Tributaries to the Lower Delaware River, 

New Jersey, 2002–07

By Ronald J. Baker and Rachel A. Esralew
2 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

nitrogen and phosphorus nutrients in the world (Sutton and 

others, 1996).

Substantial nutrient loading can contribute to toxic or 

nuisance algal blooms and degrade estuarine water quality (Granéli and Turner, 2006; Wassmann and Olli, 2004). 

Phytoplankton production (often quantified by the measurement of chlorophyll a) can reduce light penetration and deplete 

dissolved oxygen concentrations, which can in turn degrade 

submerged aquatic vegetation and associated habitat functions 

(Kennish, 1997).

Point sources such as domestic wastewater-treatmentplant discharges and industrial-waste discharge comprise 

about two-thirds of the total nutrient load to the Delaware Bay 

(Delaware Inland Bays Estuary Program, 1993). The remaining third consists of non-point sources (NPSs) such as leaking 

septic systems, farmlands, lawns, and atmospheric deposition. The quantity of storm runoff is affected by the amount 

of impervious surface in the drainage basin, which in turn is a 

function of the amount of development (including residential, 

commercial, and industrial land use), as has been demonstrated in a study by Whiley and others (2009).

Since the early 1960s, point-source discharges have been 

the main focus of Federal and State water-quality efforts in 

the Delaware River Basin (Greeley-Polhemus Group, Inc., 

1990). Since the implementation of these water-contamination 

control policies, levels of dissolved oxygen have increased, 

whereas concentrations of fecal coliform bacteria and nutrients 

have decreased in the Delaware River Estuary and Delaware 

Bay (Delaware River Basin Commission, 1994). NPSs did not 

receive significant attention until the implementation of the 

Federal Clean Water Act, Section 208, in 1970, which includes 

increased land-use regulations and encourages best-management practices (BMP) for reducing loads of contaminants, 

such as nitrogen and phosphorus, to streams from nonpoint 

sources. BMPs are practices that are determined by the State 

to be practical and effective in achieving and maintaining 

NPS loads at levels compatible with water-quality goals and 

may include stormwater management, headwater protection 

practices, or zoning restrictions on development (Lynch and 

Corbett, 1990).

In 2004, a provision was added to the Clean Water Act 

to help identify BMPs that will result in water bodies meeting 

Federal water-quality standards (U.S. Environmental Protection Agency, 2004). This provision, Section 303(d), calls for 

the establishment of total maximum daily loads (TMDLs) of 

contaminants from point and nonpoint sources to water bodies 

that do not currently meet these standards after the implementation of technology-based effluent limitations. TMDLs for 

water bodies in New Jersey are developed by the New Jersey 

Department of Environmental Protection (NJDEP) as a mechanism for reducing nutrient contaminant loads. Allocations of 

contaminant loads can be assigned to the sources contributing 

the loads in order to control and reduce the environmental degradation of a water body. Because nonpoint source loads do 

not come from discrete, identifiable sources, the assignment of 

load allocations would impart load reductions to activities that 

contribute nonpoint-source loads; the reductions are implemented through BMPs (Lehr and others, 2005).

NJDEP has initiated a watershed-based approach to 

water-quality management in order to develop TMDLs for 

water bodies throughout the State (New Jersey Department of 

Environmental Protection, 2009). NJDEP has designated 20 

watershed management areas within four watershed regions 

delineated by hydrogeologic boundaries. As part of NPS and 

stormwater-management strategies for the New Jersey portion 

of the lower Delaware River Basin, the NJDEP, U.S. Environmental Protection Agency (USEPA) Region 2, the Delaware 

River Basin Commission (DRBC), and other local New Jersey 

agencies have begun to implement BMPs in watersheds within 

the lower Delaware River Basin (Delaware River Basin Commission, 1994).

As of 2009, within the lower Delaware River Basin, 

TMDLs for total phosphorus have been proposed for 15 lakes 

and 13 tributary stream segments. Additionally, TMDLs 

for fecal coliform loads have been proposed for 36 basins, 

and 17 lakes have TMDLs for pathogens. Six TMDLs were 

Table 1. Mean annual values of total phosphorus , total nitrogen, chlorophyll-a, and water clarity as determined with using a Secchi 

disk for five trophic states. 

[μg/L, micrograms per liter; m, meter; <, less than; >, greater than]

Trophic state

Total

phosphorus

(μg/L)

Total 

nitrogen

(μg/L)

Chlorophyll a

 (μg/L)

Secchi disk 

depth 

(m) 

Ultra-oligotrophic <4 <250 <1 >12 

Oligotrophic 4-10 250-500 1-2.5 6-12 

Mesotrophic 10–35 500-1,000 2.5–8 3-6

Eutrophic 35–100 1,000-2,000 8–25 1.5-3

Hypertrophic >100 >2,000 >25 <1.5
Introduction 3

established by the NJDEP in 2004 for four stream segments 

and two impoundments along the length of the Cooper River, 

one of the streams studied in this investigation. Phosphorus, 

largely from runoff, was found to be present in unacceptably 

high concentrations for the intended ecological, consumptive, and recreational use of the Cooper River. BMPs were 

presented in the TMDL document. In order to achieve TMDL 

goals, phosphorus loads from the Cooper River Basin would 

have to be reduced by about 85 percent.

In order to establish TMDLs and implement BMPs to 

improve water quality for other streams within the lower Delaware River Basin, a better understanding of relations between 

land-use practices and non-point contaminant loading is 

needed. According to 1995–1997 land-use analysis (Lathrop, 

2000), approximately 25 percent of the lower Delaware River 

Basin is considered urban, 25 percent is agricultural land, and 

50 percent is forested or wetland areas. From 1986 to 2000 

impervious surface coverage increased in the basin as a result 

of an increase in urban development (Lathrop, 2000; Hasse 

and Lathrop, 2001) when agricultural land (farmland) was 

converted to urban use (Lathrop, 2000).

From 2003 to 2007 the U.S. Geological Survey (USGS), 

in cooperation with the NJDEP, conducted a study to determine the relation between land use and water quality in 

several tributaries to the Lower Delaware River (fig. 1). The 

objectives of this study were to (1) identify several basins of 

the lower Delaware River Basin that have different land-use 

patterns and select appropriate streamgaging and water-quality 

sampling locations; (2) collect hydrological and water-quality 

data from each sampling location during base flow and 

stormflow over several years; (3) calculate streamflow and 

determine concentrations of water-quality constituents, then 

determine the loads of each constituent for each sampling 

event, and (4) relate water-quality characteristics to land use, 

seasonality (growing and nongrowing), and hydrologic condition (base flow or stormflow). To this end, streamflow and 

loads of nitrogen and phosphorus species were measured in six 

streams in the lower Delaware River Basin during base-flow 

and stormflow conditions. Seasonal effects (growing and nongrowing seasons) on water quality and loading were considered. The water-quality constituents studied are total nitrogen, 

ammonia, nitrate plus nitrite, organic nitrogen, total phosphorus, orthophosphate, total organic carbon, total suspended 

solids, and fecal coliform and Escherichia coli bacteria. The 

scope of this investigation was constrained by the freshwater 

riverine system, and although the ultimate delivery of nutrients 

to the Delaware Bay estuary and beyond is of great environmental interest, that topic is beyond the scope of this study.

Purpose and Scope

This report presents the concentrations and estimated 

yields (area-normalized loads) of nutrients, bacteria, and 

suspended solids in six tributaries to the Lower Delaware 

River used to evaluate the relation between land use and water 

quality in the six basins. Annual loads of phosphorus and 

nitrogen species also are presented. The constituent concentration and yield values presented in this report are based on 

water-quality and streamflow data collected during base-flow 

and stormflow conditions and during growing and nongrowing 

seasons from 2003 to 2007. Graphical presentations are used 

to show how constituent concentrations and yields vary during 

base flow and stormflow in the growing and nongrowing seasons. A numerical model relating water quality and constituent 

loads to percentages of land development is described. The 

principal objectives of this report are to document nutrient 

concentrations and loads in these six tributaries to the Delaware River and to show the relation between land use and 

water quality.

Previous Investigations

The USGS, in cooperation with State and local agencies, 

has been conducting comprehensive water-quality studies in 

New Jersey since the early 1960s. Many of these studies have 

attempted to relate NPS contributions from agricultural areas 

to groundwater quality, although a few have investigated NPS 

contributions from urban and agricultural land to the quality of 

surface water. Generally, these few studies have demonstrated 

that the highest levels of nutrient loads in streams result from 

agricultural land use, although urban land use also is associated with elevated nutrient loads. The lowest levels of nutrient 

loads were found to occur in undeveloped areas and basins.

Three USGS NPS studies were conducted in the Coastal 

Plain of New Jersey. A fourth USGS study was conducted 

in a basin of the Lower Delaware River in Pennsylvania and 

Delaware. The Coastal Plain NPS studies were conducted 

in the Mill Creek Basin in Willingboro, Burlington County 

(Schornick and Fishel, 1980); in the Great Egg Harbor River 

Basin in Winslow Township, Camden County (Fusillo, 1981); 

and in the Toms River Basin in Ocean County (Hunchak-Kariouk and others, 1999; Baker and Hunchak-Kariouk, 2006). 

In Pennsylvania and Delaware, a model for the Christina 

River Basin, which drains to the Lower Delaware River, was 

constructed. The model included sites in both the Piedmont 

and Coastal Plain Physiographic Province areas of the basin 

(Senior and Koerkle, 2003). A comprehensive study of water 

quality in the Delaware River Basin was completed by Fischer 

and others (2004). This study included nutrients as well as 

pesticides, volatile organic compounds, trace elements, and 

other contaminants.

Schornick and Fishel (1980) report that runoff from the 

upstream, nonresidential part of the Mill Creek drainage basin 

had a more substantial effect on the quality of surface water 

than did runoff from the downstream residential part of the 

basin. Land use in nonresidential areas was predominantly 

agricultural with minor amounts of undeveloped and residential areas, according to the 1970s land-use survey (Lathrop, 2000). Higher concentrations and loads of nutrients in 

upstream stormwater runoff than in downstream runoff appear 
4 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

to be the result of agricultural activity. These loads from agricultural areas affected the water quality more than loads from 

residential development in the downstream part of the basin.

Fusillo (1981) reports that samples collected from 

surface-water monitoring sites on the Great Egg Harbor River 

in urban areas of Winslow Township, Camden County, New 

Jersey, had higher values for specific conductance, chloride, 

nitrate, and phosphorus than did samples from monitoring sites in less developed areas. Water samples collected 

downstream from a domestic wastewater-treatment plant has 

substantially higher concentrations of nutrients than those collected upstream from the plant. A new residential development 

has the effect of slightly increasing nutrient concentrations.

Lower Delaware Fall Line

River Basin

77° 76° 75° 74°

42°

41°

40°

39°

Delaware

River

Base from U.S. Geological Survey digital 

line graph files, 1:24,000

75° 74°

40°

39°

0 20 KILOMETERS

0 10 20 MILES

MIDDLE 

ZONE

LOWER 

ZONE

D E L A W A R E

B A Y

A

T L A

N

T I C

O

C

E

A

N

DD EE LL AAWWAA RR EE

P E N N S Y L V A N I A P E N N S Y L V A N I A

PENNSYLVANIA

NEW

JERSEY

NEW YORK

MARYLAND

DELAWARE

20 MILES

0

0

20 KILOMETERS

UPPER 

ZONE

De al ware River

17

15

16

14

18

19 13

20

11 10 09

12

C O A S T A L

P

L A I N

Figure 1. Delaware Bay and the upper, middle, and lower zones of the lower Delaware River. [Numbers indicate New Jersey 

Watershed Management Areas]
Introduction 5

Baker and Hunchak-Kariouk (2006) studied NPS contributions during stormflow and base flow in several basins 

in Ocean County, New Jersey, that had varying levels of 

development. Baker and Hunchak-Kariouk report that during 

stormflow, sites with the highest percentage of developed land 

yielded higher concentrations of ammonia, fecal coliform, suspended sediment, and phosphate, whereas sites with moderate 

development yielded higher concentrations of other nitrogen 

and phosphorus species. They also report no significant relations between groundwater contributions of nutrients (estimated by measuring concentrations during base flow) and land 

use, and hypothesize that the loads of these constituents could 

be affected by other basin characteristics, such as hydrogeology and previous land-use practices.

A regional water-quality survey of the Delaware River 

Basin was made by Fischer and others (2004). Total nitrogen 

and phosphorus concentrations were found to be greater in 

streams with the drainage basins that have high percentages 

of urban or agricultural land use. Nitrate was the predominant form of nitrogen and was detected in 95 percent of the 

streams sampled. The highest concentration measured was 

10.5 mg/L as N, and the median concentration was 0.87 mg/L 

as N. Organic nitrogen typically constituted about 20 percent 

of the total nitrogen detected. Total phosphorus concentrations exceeded 0.1 mg/L as P, a goal established by USEPA for 

minimizing nuisance plant growth, in more than 50 percent of 

samples collected from some sites. Phosphorus concentrations 

tended to be higher in stormwater samples than in base-flow 

samples.

A study of the relation between agricultural land use and 

nutrient concentrations and loads in the Coastal Plain basins 

of the Chesapeake Bay (Jordan and others, 2003) showed 

that mean concentrations of nitrogen species increased as the 

percentage of cropland in the basin increased. Phosphorus species, however, were more strongly correlated with concentrations of particulate matter than with land-use practices, and the 

nitrogen-to-phosphorus ratio varied substantially among the 

basins studied. A significant relation was identified between 

discharges of nitrogen from the basins and the input of anthropogenically derived nitrogen into the basin from all sources, 

including atmospheric deposition, fertilizers, and nitrogenfixing crop plants. 

The effects of land-use change on nutrient discharge 

from the Patuxent River watershed in Pennsylvania were 

investigated by Jordan and others (2003). Linear models were 

constructed to relate concentrations of nutrients, sediment, and 

other constituents to nonpoint and point sources of discharges 

in the watershed. It was found that conversion from undeveloped land to cropland uses had the most substantial effect on 

water quality, conversion from cropland to urban development 

had less effect, and conversion from undeveloped land to 

urban development had the least effect. The model was used 

to predict changes in the discharge of nutrients and other constituents from the basins through the year 2020 on the basis of 

current patterns of population growth.

Study Area

The tidal part of the Delaware River in southwestern New 

Jersey and southeastern Pennsylvania extends from just below 

Trenton, New Jersey, to the mouth of the Delaware Bay. The 

lower Delaware River Basin is estuarine in nature (Sutton and 

others, 1996). It covers 5,900 square miles and accounts for 47 

percent of the total drainage area of the entire Delaware River 

Basin (Velnich, 1982).

The Lower Delaware River Region is one of five water 

regions, as defined by the NJDEP (Watt, 2000). It comprises 

four watershed management areas (numbers 17–20) and occupies the area from just north of Trenton, New Jersey, to the 

mouth of the Delaware Bay. The lower Delaware River Basin 

lies entirely within the Coastal Plain Physiographic Province, 

and all streams and tributaries drain to the Delaware River 

or Delaware Bay. The Coastal Plain is characterized by flat 

topography and unconsolidated sediment (alternating layers 

of clay, silt, sand, and gravel). The sediment wedge decreases 

in thickness from south to north; the wedge is 6,500 ft thick 

at southern tip of the State and absent at the Fall Line. All 

Coastal Plain aquifers but one are confined, except at outcrop 

areas. The Kirkwood-Cohansey aquifer system is mostly 

unconfined.

Development of forested and agricultural land has 

increased since the early 1970s and is expected to continue to 

increase (New Jersey Department of Environmental Protection 

and Energy, 1993; Hasse and Lathrop, 2008). Although the 

lower Delaware River Basin remains in large part agricultural, 

land-use and land-cover digital data indicate that residential and commercial plus industrial land uses have increased 

substantially over the last 30 years (U.S. Geological Survey, 

1986; Hasse and Lathrop, 2008). As of 1997, urban land use 

accounted for 25 percent of the lower Delaware River Basin.

Water quality and streamflow were measured in six 

tributaries to the Delaware River (Blacks Creek, Lahaway 

Creek, Cooper River, South Branch Big Timber Creek, Alloway Creek, and Gravelley Run) (fig. 2). Two streams were 

selected for each of three predominant land-use types (agricultural, undeveloped, and urban). A single monitoring site was 

established on each stream. Locations of the six sites are given 

in table 2, and a summary of the land-use percentages in the 

basins draining into each stream, upstream from each monitoring site, are given in table 3. There are no known point sources 

within these basins.
6 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

*#

*#

*#

*#

*#

*#

NEW JERSEY

01467327

0146452750

01464445

01467148

0146452750

Delaware

River

D E L A W A R E

B A Y

A

T L A

N

T I C

O

C

E

A

N

DD EE LL AAWWAA RR EE

P E N N S Y L V A N I A P E N N S Y L V A N I A

01411955

75°30' 75° 74°30' 74°

40°

39°

30'

39°

Base from U.S. Geological Survey digital 

line graph files, 1:24,000

0 20 KILOMETERS

0 10 20 MILES

USGS site ID

01467327

0146452750

01467148

01464445

01411955

01482890

Lahaway Creek near Prospertown 

Gravelly Run at Laurel Lake

Alloway Creek near Watson's Corner

Site name

South Branch Big Timber Creek at Grenloch

Blacks Creek near Chesterfield

Cooper River at Route 561 at Haddonfield

01467327 #

Lower Delaware Region 

boundary

Subbasin boundary

Monitoring site and U.S. Geological 

Survey (USGS) identification number (ID)

EXPLANATION

Figure 2. Locations of water-quality monitoring sites and subbasins in the lower Delaware River Basin Watershed in New Jersey. 
Methods of Study 7

Methods of Study

Samples for water-quality analysis were collected and 

streamflow was measured during the growing and nongrowing seasons during periods of base flow and stormflow from 

September 2003 to April 2007. At all sites, samples were 

collected, and water stage was measured by NJDEP personnel 

from the Bureau of Marine Water Monitoring (BMWM) and 

the Bureau of Freshwater and Biological Monitoring (BFBM). 

BMWM performed all laboratory analyses, and qualityassurance analyses were performed by the BFBM. Waterquality data used in this report are maintained by the NJDEP, 

BMWM, and are available in electronic form upon request 

from the NJDEP, BMWM, PO Box 405, Stony Hill Rd, Leeds 

Point, NJ, 08220. USGS personnel measured stream stage 

and streamflow and developed stage-to-streamflow relations. 

Streamflow values were calculated by USGS personnel from 

stream-stage data and stage-discharge relations (rating curves). 

The dates of data collection and types of data collected at each 

site during each monitoring event are listed in table 4.

Table 2. Locations of six sites in the lower Delaware River Basin, New Jersey, at which streamflow and water quality were 

monitored during eight storms from 2002 to 2007.

[USGS, U.S. Geological Survey; WMA, watershed management area]

USGS station name

USGS

station

identifier

USGS

station

number

(figure 1)

Station latitude and longitude WMA

Lahaway Creek Tributary near Prospertown UND1 01464445 Lat 40° 06’51”; Long 74° 27’31” 20

Gravelly Run at Laurel Lake UND2 01411955 Lat 39° 20’14”; Long 75° 03’04” 17

Blacks Creek near Chesterfield AGR1 0146452750 Lat 40° 06’52”; Long 74° 40’49” 20

Alloway Creek near Watson Corner AGR2 01482890 Lat 39° 35’13”; Long 75° 18’22” 18

Cooper River at Route 561 at Haddonfield URB1 01467148 Lat 39° 53’42”; Long 75° 01’29” 19

South Branch Big Timber Creek Tributary at Grenloch URB2 01467327 Lat 39° 46’46”; Long 75° 03’15” 18

Table 3. Area of, and land-use distribution in 2002 in, drainage basins upstream from six sites in the lower Delaware River Basin, 

New Jersey, at which streamflow and water quality were monitored during eight storms during 2002–07.

[mi2, square mile; USGS, U.S. Geological Survey; station identifiers are shown in table 2]

USGS

station

identifier

Drainage

area 

(mi2

)

Land use

Land-use distribution (percent)

Agricultural Barren Forested Urban Water Wetland

UND1 2.3 Moderately undeveloped 4.6 1.5 69.4 13.6 0.4 10.6

UND2 3.3 Pristine 5.8 0.1 78.8 0.9 0.0 14.4

AGR1 13.2 Moderately agricultural 55.4 0.2 14.1 10.0 1.6 18.6

AGR2 3.0 Highly agricultural 76.6 1.1 8.2 7.5 0.3 6.2

URB1 17.8 Moderately urban 1.3 1.9 17.0 69.2 1.0 9.5

URB2 4.3 Moderately urban 3.9 0.2 14.1 73.7 1.5 6.6
8 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

Site Selection

The sites were selected on the basis of (1) the land-use 

percentages in the basin, (2) the ability to establish an acceptable stream stage-to-streamflow relation (rating curve), and (3) 

the suitability of the site for water-quality sample collection.

To select the water-quality sampling sites, land-usedistribution data (U.S. Geological Survey, 1986; New Jersey 

department of Environmental Protection, 2000), recent aerial 

photographs, county street maps, soil surveys (Markley, 1962, 

1971, 1988), and field observations were used in conjunction 

with a geographic information system to evaluate land use in 

the contributing drainage areas. For this investigation, the six 

level I land-use categories identified (Anderson and others, 

1976) were grouped into three main categories: (1) urban, also 

consisting of most non-agricultural barren areas; (2) agriculture; and (3) undeveloped, consisting of forested plus wetland 

areas.

Few basins could be identified that had a single, predominant land use. Therefore, several sites were selected so that 

the contributing area had at least one land use that comprised 

more than 50 percent of the drainage basin, and this land use 

was designated as the predominant land use (table 3).

The monitoring site on Blacks Creek (AGR1; fig. 3) 

located near Chesterfield in Burlington County, New Jersey, 

Table 4. Description of monitoring events at six sites on streams in the lower Delaware River Basin, New Jersey, 2003–07.

[USGS, U.S. Geological Survey; Growing season: April 1–October 31; Non-growing season, November 1–March 31; yes, event was monitored; no, event 

was not monitored]

Event

number Dates Event type Season

USGS station identifier

UND1 UND2 AGR1 AGR2 URB1 URB2

1 09/12/2003 Base flow Growing Yes Yes Yes Yes Yes Yes

2 10/26/2003 Base flow Growing No Yes Yes Yes Yes Yes

3 10/26/2003-10/27/2003 Stormflow Growing No Yes Yes Yes Yes Yes

4 11/18/2003 Base flow Non-growing Yes Yes Yes Yes Yes Yes

5 11/18/2003-11/20/2003 Stormflow Non-growing Yes Yes Yes Yes Yes Yes

6 04/01/2004 Base flow Growing Yes No Yes Yes Yes Yes

7 04/01/2004-04/04/2004 Stormflow Growing Yes No Yes Yes Yes Yes

8 09/27/2004 Base flow Growing Yes Yes Yes Yes Yes Yes

9 09/27/2004-09/29/2004 Stormflow Growing Yes Yes Yes Yes Yes Yes

10 10/06/2005 Base flow Growing Yes Yes Yes No No No

11 10/06/2005-10/08/2005 Stormflow Growing Yes Yes Yes No No No

12 11/16/2005 Base flow Non-growing No No No Yes Yes Yes

13 11/16/2005-11/17/2005 Stormflow Non-growing No No No Yes Yes Yes

14 05/11/2006 Base flow Growing Yes Yes Yes Yes Yes Yes

15 05/11/2006-05/13/2006 Stormflow Growing Yes Yes Yes Yes Yes Yes

16 10/17/2006 Base flow Growing Yes Yes Yes Yes Yes Yes

17 10/17/2006-10/19/2006 Stormflow Growing Yes Yes Yes Yes Yes Yes

18 03/15/2007 Base flow Non-growing Yes Yes Yes Yes Yes Yes

19 03/15/2007-03/19/2007 Stormflow Non-growing Yes Yes Yes Yes Yes Yes
Methods of Study 9

OCEAN

COUNTY

MONMOUTH

COUNTY

MERCER

COUNTY

Base from U.S. Geological Survey digital 

line graph files, 1:24,000

74°43' 74°42' 74°41' 74°40' 74°39' 74°38' 74°37' 74°36' 74°35' 74°34' 74°33'

40°

04'

40°

05'

40°

06'

40°

07'

40°

08'

0 1 2 MILES

0 2 KILOMETERS

Bordentown 

Township

North Hanover Township

Upper 

Freehold 

Township

Chesterfield Township

Springfield Township

Mansfield Township

Monitoring site AGR1 

(U.S. Geological Survey 

station 0146452750)

Assiscunk

Creek

Craft's Creek

Bacon's

Run

Black's Creek

#

55.4%

0.2%

14.1%

10.0%

1.6% 18.6%

EXPLANATION

LAND USE - From N.J. Department of Environmental 

Protection, digital data file, 2002

Agriculture

Barren Land

Forest

Urban

Water

Wetlands

Drainage area: 13.2 square miles

# Monitoring site

Lower Delaware 

River Basin

Site AGR1

subbasin

Figure 3. Land use in site AGR1 drainage basin, lower Delaware River Basin in New Jersey.
10 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

drains an area of 13.2 mi2, and the entire stream is classified 

as FW11 using the surface-water-quality standards for New 

Jersey (New Jersey Department of Environmental Protection, 

2008). This basin is moderately agricultural (55.4 percent) 

with cropland and pastureland throughout the basin and with 

several smaller horticultural land-use areas in the upper basin. 

Deciduous forest and wooded wetlands, which account for 

about 33 percent, are dispersed throughout the basin and create 

buffer areas around the streams and tributaries. The wetlands 

are primarily located in the lower part of the basin. Urban 

development (mostly rural single-unit residences) currently 

(2007) comprises about 10 percent of the basin area. During 

1986–97, urban development increased by more than 50 percent, about 85 percent of which was converted from agricultural land use. Urban development continues to increase while 

forest, wetland, and agricultural areas decrease (U.S. Geological Survey, 1986).

The monitoring site on Alloway Creek (AGR2; fig. 4), 

located near Watson’s Corner in Salem County, New Jersey, receives water that drains an area of 3.0 mi2

. The entire 

stream is designated as FW2/SE11 (New Jersey Department of 

Environmental Protection, 2008), although the location of the 

monitoring site is in freshwater. This basin is highly agricultural (76.6 percent) and includes mostly cropland and pastureland with a small confined feeding lot near the basin outlet and 

several smaller horticultural land-use areas in the upper part 

of the basin. Urban development in this basin, which is mostly 

residential, is minimal (about 7.5 percent).

The monitoring site on Prospertown Brook, which is a 

tributary to the Lahaway Creek (UND1; fig. 5), is located in 

Plumsted and Jackson Townships, Ocean County, New Jersey; 

the site receives water from an area of 2.3 mi2. This part of the 

Lahaway Creek is designated FW2 (New Jersey Department 

of Environmental Protection, 2008). This basin is moderately 

undeveloped; mixed deciduous and coniferous forested and 

wetland areas comprise 80 percent of the basin. Cropland 

accounts for less than 5 percent of the basin, and most of this 

is in one localized field 0.3 mi upstream from the monitoring site. Urban land uses constitute 13.6 percent of the basin 

and are mostly low density and suburban residential areas. 

The suburban areas are located in the lower part of the basin. 

Development has increased by more than 35 percent during 

1

 Most waterbodies within New Jersey have been assigned a surface-waterquality classification (New Jersey Department of Environmental Protection, 

1998). Freshwater bodies identified as FW1originate in and lie wholly within 

Federal or State parks, forests, fish and wildlife lands, and other special holdings and are to be maintained in their natural state of quality and not subjected 

to any manmade wastewater discharges. Freshwater bodies designated FW2 

are water used for maintenance, migration and propagation of the natural and 

established biota, primary and secondary contact recreation (swimming, boating, and fishing), industrial and agricultural water supply, and public water 

supply after conventional filtration treatment. Regulations for SE1 waters, 

which are saline waters of estuaries, are similar to FW2 water regulations and 

also permit shellfish harvesting. C1 is a specific designation for the protection 

from measurable changes in the water-quality characteristics clarity, color, 

scenic setting, and other characteristics of aesthetic value, and exceptional 

ecological significance, exceptional recreational significance, exceptional 

water-supply significance, or exceptional fisheries resource(s).

1986–97 and consists mostly of rural and low-density residential areas with some suburban development.

The monitoring site on the Gravelly Run (UND2), near 

Laurel Lake in Cumberland County, New Jersey, receives 

water from an area of 3.3 mi2 and is located entirely within 

boundaries of the Edward G. Bevan Wildlife Management 

Area2 (fig. 6). Scheduled measurements of various waterquality constituents (including all constituents investigated 

in this study) have been made at this site by the USGS since 

1983. Gravelly Run is classified as an FW2 (C1) stream. This 

basin is almost entirely undeveloped, with the exception of 

several paved and unpaved access roads. Most of the area 

(more than 99 percent) consists of forests—upland deciduous 

and coniferous forests— and wetlands. Several open areas are 

maintained to preserve wildlife habitat. There is no agricultural activity in this basin. Wildlife Management Areas are 

protected by the New Jersey Department of Environmental 

Protection, so this basin will most likely remain undeveloped 

in the future.

The monitoring site on Cooper River (URB1; fig. 7), 

located in Haddonfield in Camden County, New Jersey, 

receives water from an area of 17.8 mi2, and the entire stream 

is classified FW21 (New Jersey Department of Environmental 

Protection, 2004a). This basin is moderately urbanized (about 

69.2 percent) and includes mostly scattered medium-density 

residential areas (suburban in nature) and commercial and 

business districts. Urban areas are mostly concentrated near 

the lower part of the basin; agricultural, forested, wetland, 

and other land uses are mostly located at the basin headwaters. Within the study basin, two small tributaries to the upper 

Cooper River—Nicholson Branch and Woodcrest Creek—

drain areas used for extractive mining, which may increase 

erosion during stormflow and cause increased concentrations 

of suspended sediment and total phosphorus. Mining land use 

may cause increased acidity during stormflow (Matter and 

Ney, 1981). A 0.3 mi2 golf course area drains into the Woodcrest Creek. Trends in development during 1986–97 indicate 

that conversion to urban land uses, mostly suburban residential 

development, has increased only slightly (5 percent), although 

during this period forested and wetland areas have decreased 

by 15 percent (U.S. Geological Survey, 1986; Lathrop, 2000).

The monitoring site on South Branch Big Timber Creek 

(URB2), located in Grenloch in Gloucester County, New 

Jersey, receives water that drains an area of 4.3 mi2

 (fig. 8). 

South Branch Big Timber Creek drains into the Big Timber 

Creek, which is classified FW2 for the entire length of the 

stream (New Jersey Department of Environmental Protection, 

2008). This basin is moderately urban (about 73.7 percent), 

mostly suburban areas and commercial districts. Rural and 

low density residential areas occupy the eastern and western 

edges of the basin. A 0.2 mi2 golf course is located near a 

2

 The Edward G. Bevan Wildlife Management Area is administered by the 

New Jersey Division of Fish and Wildlife, Bureau of Land Management. New 

Jersey's Wildlife Management Area Systems are protected areas that provide 

public access to fishing, hunting, and various other outdoor recreational activities. 
Methods of Study 11

76.6%

1.1%

8.2%

7.5%

0.3%

6.2%

Lower Delaware 

River Basin

Site AGR2

subbasin

Drainage area: 3.0 square miles

EXPLANATION

LAND USE - From N.J. Department of Environmental 

Protection, digital data file, 2002

Agriculture

Barren Land

Forest

Urban

Water

Wetlands

# Monitoring site

Base from U.S. Geological Survey digital 

line graph files, 1:24,000

75°19' 75°18' 75°17' 75°16' 75°15' 75°14'

39°

35'

39°

36'

Upper Pittsgrove Township

Alloway Township

Pilesgrove Township

Watsons

Corner

Monitoring site AGR2 

(U.S. Geological Survey 

station 01482890)

#

0 0.75 1.5 MILES

0 1 2 KILOMETERS

Figure 4. Land use in site AGR2 drainage basin, lower Delaware River Basin in New Jersey.
12 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

EXPLANATION

LAND USE - From N.J. Department of Environmental 

Protection, digital data file, 2002

Agriculture

Barren Land

Forest

Urban

Water

Wetlands

Drainage area: 2.3 square miles

# Monitoring site

Lower Delaware 

River Basin

Site UND1

subbasin

4.6% 1.5%

69.4%

13.6%

0.4%

10.6%

Plumsted Township

Jackson Township

Upper 

Freehold 

Township

MONMOUTH COUNTY

OCEAN COUNTY

Base from U.S. Geological Survey digital 

line graph files, 1:24,000

74°29' 74°28' 74°27' 74°26'

40°

06'

40°

07'

0 0.5 1 MILE

0 0.75 1 KILOMETER

Lahaway

Creek

Tributary

Lahaway Creek Tributary

Shan nae Bro ok

Tributary

Prospertown Brook

Tributary

To ms River Tributary

Monitoring site UND1 

(U.S. Geological Survey 

station 01464445)

#

Figure 5. Land use in site UND1 drainage basin, lower Delaware River Basin in New Jersey.
Methods of Study 13

EXPLANATION

LAND USE - From N.J. Department of Environmental 

Protection, digital data file, 2002

Agriculture

Barren Land

Forest

Urban

Water

Wetlands

Drainage area: 3.3 square miles

# Monitoring site

Lower Delaware 

River Basin

Site UND2

subbasin

5.8%

0.1%

78.8%

0.9% 14.4%

Downe Township

Commercial Township

Milleville 

City

Lawrence 

Township

Joshua

Branch

Pine Branch

Gravelly Run

Dividing

Creek

Buckshutem

Creek

Monitoring site UND2 

(U.S. Geological Survey 

station 01411955)

0 0.9 1.8 KILOMETERS

0 0.6 1.2 MILES

75°06' 75°05' 75°04' 75°03'

39°

19'

39°

20'

#

Base from U.S. Geological Survey digital 

line graph files, 1:24,000

Figure 6. Land use in site UND2 drainage basin, lower Delaware River Basin in New Jersey.
14 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

EXPLANATION

LAND USE - From N.J. Department of Environmental 

Protection, digital data file, 2002

Agriculture

Barren Land

Forest

Urban

Water

Wetlands

Drainage area: 17.8 square miles

# Monitoring site

Lower Delaware 

River Basin

Site URB1

subbasin

1.3% 1.9%

17.0%

69.2%

1.0%

9.5%

Haddon 

Township

Gloucester Township

Cherry Hill Township

Evesham Township

Berlin Township

0 2.5 5 KILOMETERS

0 2 4 MILES

75°06' 75°04' 75°02' 75° 74°58' 74°56' 74°54'

39°

50'

39°

52'

39°

54'

Newton Creek

Almonesson Creek

B gi Tmi ber Creek

Pines Run

Millard Creek

Woodcrest Creek

Tindale Run

North Branch Cooper Rive r

South Branch

Pennsauken Creek

Barton Run

Coope r River

Monitoring site URB1 

(U.S. Geological Survey 

station 01467148)

#

BURLINGTON COUNTY

CAMDEN COUNTY

Base from U.S. Geological Survey digital 

line graph files, 1:24,000

Figure 7. Land use in site URB1 drainage basin, lower Delaware River Basin in New Jersey.
Methods of Study 15

EXPLANATION

LAND USE - From N.J. Department of Environmental 

Protection, digital data file, 2002

Agriculture

Barren Land

Forest

Urban

Water

Wetlands

# Monitoring site

Lower Delaware 

River Basin

Site URB2

subbasin

1.3% 1.9%

17.0%

69.2%

1.0%

9.5%

South Branch

Big Timbe r Creek

Base from U.S. Geological Survey digital 

line graph files, 1:24,000

75°06' 75°05' 75°04' 75°03' 75°02' 75°01'

39°

44'

39°

45'

39°

46'

39°

47'

Grenloch

0 1 2 MILES

0 2 KILOMETERS

Washington Township

Gloucester Township

Deptford

Township

# Monitoring site URB2 

(U.S. Geological Survey 

station 01467327)

Drainage area: 4.3 square miles

Mantua Creek

Porch

Branch

Bethel Run

CAMDEN COUNTY

GLOUCESTER COUNTY

North Bra nch

Big Timber Creek

Figure 8. Land use in site URB2 drainage basin, lower Delaware River Basin in New Jersey.
16 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

tributary 0.6 mi upstream from the monitoring site, which may 

contribute to elevated total nitrogen and phosphorus loads 

during stormflow and base flow from applications of fertilizers (Walker and Branham, 1992). About 3.9 percent of the 

basin is agricultural; one distinct cropland area is located near 

the basin headwaters. The remaining forested and wetland 

areas, which account for 20.7 percent, are highly fragmented 

throughout the basin, and most are located as buffers along 

the stream boundaries. A 1,500 ft2 impoundment surrounded 

by deciduous wooded wetland is located about 2 mi upstream 

from the monitoring site. During 1986–97, forested and 

wetland areas in the basin decreased by about 15 percent, and 

agricultural areas decreased by more than 50 percent; suburban residential and commercial development increased proportionally (U.S. Geological Survey, 1986; Lathrop, 2000). These 

trends of urbanization may be continuing. The remaining 

undeveloped land in this basin is mostly fragmented, however, 

and may reduce the amount of total area available for development in the future.

Data Collection

Water-Quality and Streamflow Data

Water-quality samples were collected and stream stage 

was measured simultaneously eight times during base flow and 

eight times during stormflow at each site. In most cases, baseflow measurements were made within 1 day of each storm 

sample. Measurements were made during the growing season 

(April 1–October 31) and nongrowing season (November 1–

March 31). The dates for the growing and nongrowing seasons 

are based on the average times of the first and final frosts in 

New Jersey (Ruffner and Bair, 1977).

For sample collection during base flow, a maximumrainfall criterion of less than 0.1 in. during the 5 days prior 

to sampling was initially specified to ensure that the stream 

had returned to base flow after the previous stormflow event. 

The beginning of base flow is defined as the time after the 

cessation of precipitation when direct runoff into the stream 

has ended (Gray, 1970). At this time, the falling limb of the 

hydrograph typically assumes the appearance of exponential 

decline. USGS real-time streamgage stations located near each 

selected monitoring station were used as references. The six 

tributaries returned to base flow 1.5 to 3 days after the end of 

precipitation during three precipitation events (November 7 to 

December 8, 2004), which is consistent with the relation given 

by Linsley and others (1975):

N = A0.2 , (1)

where

N = number of days between the storm peak 

and the end of runoff, and 

A = drainage-basin area, in square miles.

In order to assess whether base-flow conditions 

have been reached, real-time stream-stage data at several 

USGS sites were viewed on the NWIS website. Each study 

site was assigned a reference site, located on a nearby 

stream of similar size. Table 5 lists the reference sites, 

which were accessed at http://waterdata.usgs.gov/nj/nwis/

current/?type=flow&group_key=basin_cd 

in order to assess whether base-flow conditions had been 

reached. A map showing the locations of the reference sites is 

shown at http://waterdata.usgs.gov/nj/nwis/rt.

A minimum-rainfall criterion for sample collection during 

stormflow in the growing and nongrowing season, 0.5 in., was 

based on precipitation data collected at Trenton, Wrightstown, 

Mount Holly, Caldwell, and Millville, New Jersey, weather 

stations operated by the National Oceanic and Atmospheric 

Administration.

Water-quality constituents that were analyzed are shown 

in table 6. All water-quality analyses were conducted by 

NJDEP personnel. Values of pH, specific conductance, stream 

stage, and temperature were continuously monitored during 

each event using a YSI 6000-series water-quality monitoring 

system (sonde), which measured and recorded a value for each 

constituent every 5 to 15 minutes.

Stream stage and streamflow (discharge) were measured 

at five of the six sites over a range of flow conditions from 

base flow to stormflow. Discharge for the sixth site, URB1, 

was determined from data supplied by the USGS real-time 

streamgage station at Cooper River at Haddonfield (station 

located 01467150, located 0.9 mi downstream).

During base flow, stream stage was measured manually 

from staff plates and reference marks at the time the waterquality samples were collected. During most storms, stream 

stages were automatically recorded every 5 to 15 minutes by 

the sondes. Stream stage also was measured manually using 

staff plates at the beginning, middle, and end of most storms in 

order to confirm the sonde records.

Stream stages measured by the pressure transducer in the 

sondes (automated measurements) were verified by occasionally making manual stream-stage measurements. Stream-stage 

measurements obtained by directly reading the stage from a 

staff plate or reference mark (manual measurements, fig. 9) are 

considered more reliable than automated measurements.

During base flow, water samples were collected and discrete measurements of specific conductance, pH, temperature, 

and dissolved measurements were made. Automated samplecollection equipment was used to collect water samples 

from each of the six study sites for analysis for chemical and 

biological constituents. Samples were not collected at regularly timed intervals but, rather, were timed so that collection 

occurred during each limb of the hydrograph. Due to logistical 

issues, unpredictability of storm duration, and personnel safety 

concerns, samples were not collected during the entire duration of the storm.
Methods of Study 17

Determination of Yields

Yields for total nitrogen, dissolved ammonia, dissolved 

nitrate, organic nitrogen, filtered orthophosphate, total suspended solids, and fecal coliform bacteria for all monitoring 

sites were computed by using the following equation:

Y = (C x Q x f)/A , (2)

where

Y = pounds per day per square mile or most 

probable number per day per square mile;

C = measured concentration, in micrograms 

per liter or most probable number per 100 

microliters;

Q = instantaneous streamflow, in cubic feet per 

second;

f = conversion factor equal to 0.0053936 

pound per microgram times seconds per 

day, times liters per cubic feet ((lb/μg)

(s/d)(L/ft3)) if the concentration is in 

micrograms per liter or 2.45 x 107 seconds 

per day times milliliters per cubic feet 

((s/d)(mL/ft3

)) if the concentration is in 

most probable number per 100 milliliters, 

and

A = drainage area, in square miles.

Data Evaluation

Hydrologic data consist of stream stage and streamflow 

measurements. Stream stage-to-streamflow relations (rating 

curves), prepared from simultaneous discharge and streamstage measurements, were used to convert stream-stage values 

to discharge values. Water-quality constituent concentrations 

and yields were then evaluated using nonparametric statistical methods to determine relations between water quality and 

streamflow, season, and percentage of development in the 

basins.

Annual loads of each constituent were determined in 

the following manner. The event-mean concentration of each 

constituent was determined, and then multiplied by the total 

streamflow for the monitoring period to calculate the total 

mass of the constituent for the monitoring event. The annual 

load is obtained by multiplying the total mass by the ratio of 

annual rainfall divided by the rainfall that produced the event.

Hydrologic Data

Stage-discharge relations, or rating curves, were developed from the simultaneous stream-stage and discharge 

measurements and were used to convert stream-stage values at 

the time of sampling to discharge values. Rating curves were 

developed by using standard USGS streamgaging procedures 

as described by Rantz and others (1982). An example of a rating curve is shown in figure 10.

Rating curves developed for all sites showed reliable 

correlations between stream stage and discharge. Discharge 

values for sites AGR1, UND1, and URB2 could be determined 

from a single rating curve each. Determining discharge for site 

UND2 required two rating curves, one before and one after 

July 2004. The stage-to-streamflow relation for site AGR2 was 

inconsistent and was found to be properly represented by two 

different rating curves. The rating curve calculated using discharge measurements made closest, by date, to each sampling 

event was selected.

Streamgaging was not conducted at monitoring site 

URB1. Discharge at this site was estimated using data from 

the USGS real-time streamgage station at Cooper River at 

Haddonfield (USGS station 01467150), located approximately 

5,000 ft downstream from the sampling site URB1. An equation was developed to estimate the instantaneous discharge 

at site URB1 by using (1) the area of the basin draining to 

site URB1 and station 01467150, (2) the discharge measured 

at station 01467150 at 15-minute intervals in real time, (3) 

the relation between discharge and stream velocity at station 

01467150 (gathered from manual discharge-measurement data 

collected since 1963), and (4) the distance between the two 

sites. This mathematical procedure requires three steps: (1) 

Table 5. Reference sites used to determine the number of days between the end of a storm and the return to stream base flow for 

six streams in the lower Delaware River Basin, New Jersey.

[USGS, U.S. Geological Survey]

Project 

site

USGS

station

number

Reference site

USGS

station

number

Days from end 

of storm to

base flow

Alloway (AGR2) 01482890 Salem River at Woodstown 01482500 2.0

Gravelly Run (UND2) 01411955 Cohansey River at Seeley, NJ 01412800 2.5

Blacks Creek (AGR1) 0146452750 Crosswicks Creek at Extonville 01464500 3.0

Cooper River (URB1) 01467148 Cooper River at Haddonfield 01467150 1.5

Big Timber (URB2) 01467327 Raccoon Creek near Swedesboro 01477120 2.5

Lahaway (UND1) 01464445 Crosswicks Creek at Extonville 01464500 3.0
18 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07 Table 6. Analytical methods used for surface-water samples. [μg/L, micrograms per liter; mL, milliliter; CFU, colony-forming units; Cd Reduction, cadmium reduction; μS/cm, microsiemens per centimeter at 25 degrees Celsius; NTU, Nephelometric Turbidity Units; NJDEP, New Jersey Department of Environmental Protection; NA, not applicable; USEPA, U.S. Environmental Protection Agency; Std Meth, Standard Methods for the Examination of water and wastewa- ter; E. Coli, Escherichia coli bacteria; ed., edition] Constituent/characteristic Unit Instrument/method Filtered water Reporting Limit Analytical method (or equivalent) Method Organization/source Ammonia μg/L Automated Phenate Yes 18.97 μg/L 4500-NH3 Std Meth 21st ed. Dissolved oxygen μg/L YSI sonde No 0.1 μg/L NA NJDEP E. Coli bacteria CFU per 100mL Plate count No 3 CFU/100mL 9213 Std Meth 21st ed. Enterococcus bacteria CFU per 100mL Plate count No 3 CFU/100mL 9230 Std Meth 21st ed. Fecal coliform CFU per 100mL Plate count No 10 CFU/100mL 9222 Std Meth 21st ed. Hydrolyzable phosphorus μg/L Persulfate/ascorbic acid Yes 10 μg/L 4500-P Std Meth 21st ed. Nitrate plus nitrite μg/L Automated Cd Reduction Yes 22.50 μg/L 353.3 USEPA Nitrite μg/L Ion chromatography Yes 3 μg/L 4110 Std Meth 21st ed. Organic nitrogen μg/L Kjeldahl Yes 0.1 μg/L 4500-N Std Meth 21st ed. Ortho plus hydrolyzable phosphorus μg/L Persulfate/ascorbic acid No 19.76 μg/L 4500PI Std Meth 21st ed. Orthophosphate μg/L Ascorbic acid No 7.09 μg/L 365.5 USEPA pH Standard units YSI sonde No 0-14 NA NJDEP Specific conductance μS/cm YSI sonde No 1 μS/cm 2520B Std Meth 21st ed. Total nitrogen μg/L Kjeldahl No 36.44 μg/L 351.2 USEPA Total organic carbon μg/L Persulfate-UV No 1 μg/L 5310 Std Meth 21st ed. Total phosphorus μg/L Persulfate/ascorbic acid No 0.1 μg/L 4500-P Std Meth 21st ed. Total suspended solids μg/L Non-filterable Residue by Drying Oven No 1 μg/L 160.2 USEPA Turbidity NTU YSI sonde no 1 NTU NA NJDEP References: U.S. Environmental Protection Agency, 1983, Methods for chemical analysis of water and wastes: Cincinnati, OH, USEPA, March 1983, EPA600-4-79-020, Parsons, T.R. and others, 1984, A manual of biological and chemical methods for seawater analysis: Oxford, Pergamon Press, 184 p. American Public Health Assoc., 1998, Standard methods for the examination of water and wastewater. (2nd ed.), Washington, D.C., American Public Health Assoc, 1368 p. Zimmerman, C.F. and Keefe, C.W., 1997, Determination of orthophosphate in estuarine and coastal waters by automated colorimetric analysis, Method 365.5, Revision 1.4: Cincinnati, OH, U.S. Environmental Protection Agency, September 1997, 9 p. 
Methods of Study 19

estimation of the discharge at site URB1 based on discharges 

observed at station 01467150 by proportionally correcting for 

drainage areas, (2) calculation of the time of travel for differences in discharge between the URB1 and station 01467150 

based on velocities observed at varying streamgage heights at 

station 01467150, and (3) application of the time correction to 

site URB1 in order to assign the correct time to each calculated discharge value at URB1. The discharge received by site 

URB1 was calculated using the following formula based on 

measured discharge at station 01467150 and the difference 

between drainage basin areas of the two sites:

Quss = Qdss * [Auss / Adss ]n , (3)

where

Quss = discharge estimated at site UR1(upstream),

Qdss = discharge estimated at station 01467150 

(downstream),

Auss = drainage area at site UR1 (17.8 mi2),

Adss = drainage area at station 01467150 

(17.0 mi2), and 

n = constant for drainage (Coastal Plain 

drainage, n = 0.93).

A correction was needed to account for a time lag 

between estimated velocities at the upstream site and downstream station. The method of Seddon (1900) as modified by 

Rantz and others (1982) was used.

Discharge Hydrograph Extension and Base-Flow 

Separation

Stage measurements were made manually at the beginning of each storm and during the rising limb of the hydrograph, but for most storms, only a few measurements were 

made during the falling limb of the hydrograph. In order to 

quantify the total discharge from each storm at each monitoring site, it was necessary to extend the storm-stage hydrographs in time and calculate discharge volumes for the falling 

limbs. This was accomplished by estimating the time at which 

runoff ended and the discharge value at that time, then applying an exponential function, which describes discharge as a 

-0.4 

-0.35 

-0.3 

-0.25 

-0.2 

-0.15 

-0.1 

-0.05 

0.05 

0.1 

0.15 

-0.4 -0.2 0 0.2 0.4 0.6 0.8 1 1.2 

LOG GAGE HEIGHT ABOVE ARBITRARY DATUM, IN FEET 

LOG STREAMFLOW, IN CUBIC FEET PER SECOND 

0 

Calculated rating curve 

Measured streamflow and 

gage height 

Figure 9. Example of a rating curve used for determining streamflow from measured stream stage for site UND2, Gravelly Run at Laurel 

Lake, New Jersey. 
20 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

function of time, to the flow during the falling limb of the 

hydrograph. For the hydrograph extensions presented here it 

was assumed that precipitation ended at the time of the last 

measurement of streamflow. Additional precipitation, runoff, 

and stormflow were not considered in subsequent load calculations. Therefore, load calculations were made only from 

water-quality and measured streamflow data, and projected 

attenuation of loads from measured values; no assumptions 

were made about streamflow or water quality from unmonitored portions of storms.

The number of days between the storm peak and the end 

of runoff was estimated using equation (1). The base flow 

measured before precipitation began was used as the final 

base-flow value for the end of the event.

Discharge during the falling limb of a hydrograph 

decreases exponentially over time (Gray, 1970) and can be 

expressed as

Q2 = Q1K-Δt , (4)

where

Q1 and Q2 = discharge rates at two times during the 

falling limb;

K = constant, and 

t = time elapsed between measurements.

The equation can be modified slightly to describe exponential decline in discharge from the last stage measurement 

(Q1) to the end of runoff (Q2).

Q2 = Q1e-bΔt , (5)

where

e = base of the natural logarithm.

The constant b is determined by setting Q2 to the baseflow discharge value, defining Δt as the elapsed time between 

the last stage measurement and the end of runoff, and solving 

for b.

Base-flow separation was approximated by drawing a 

line from the base-flow discharge value immediately before 

the storm to the discharge value at the end of the storm, which 

1.1 

1.2 

1.3 

1.4 

1.5 

1.6 

1.7 

10/17/06 0:00 10/17/06 4:48 10/17/06 9:36 10/17/06 14:24 10/17/06 19:12 10/18/06 0:00 10/18/06 4:48 10/18/06 9:36 

STREAM STAGE, IN FEET 

DATE AND TIME 

Automatic stream-stage measurement 

Manual stream-stage measurement 

Figure 10. Example of a stream-stage hydrograph which includes automatic and manual stream-stage measuements for URB2, South 

Branch Big Timber Creek Tributary at Grenloch, New Jersey, October 17–18, 2006.
Methods of Study 21

corresponds to the end of runoff. Therefore, the base-flow discharge volume during a storm is the represented by the area of 

the quadrilateral on the hydrograph defined by the beginning 

and ending times of the storm and the associated streamflow 

values.

Water-Quality Data

All analyses were conducted by the NJDEP Bureau of 

Marine Water Monitoring Leeds Point Laboratory. Water 

samples were analyzed for total nitrogen, ammonia, nitrate 

plus nitrite, total phosphorus, orthophosphorus, total suspended solids, and bacteria (Escherichia coliform (E. coli) 

and fecal coliform). Nitrate was calculated as the difference 

between nitrate plus nitrite and nitrite. Organic nitrogen was 

calculated as the difference between total nitrogen and the sum 

of ammonia and nitrate plus nitrite.

In this report, concentrations of all nitrogen species are 

presented in micrograms per liter of nitrogen (N). Concentrations of total phosphorus and orthophosphate are presented 

in micrograms per liter of phosphorus (P). Concentrations of 

total suspended solids are expressed as milligrams per liter, 

and concentrations of bacteria are presented in the most probable number of bacteria per 100 milliliters of sample. The 

term “total concentration” refers to concentrations of analytes 

determined from unfiltered water samples. 

Statistical Methods

A statistical package (Spotfire S-Plus 8.1, Tibco Software, Inc., Palo Alto, CA) was used for all statistical calculations and related graphics. Base-flow and stormflow data were 

evaluated separately. Null hypotheses were developed to test 

for differences among concentrations and yields of each constituent in water samples from the six sites and differences in 

water quality between growing and nongrowing seasons. 

Because water-quality data tend to be non-normally 

distributed, tend to be censored by detection limits, and often 

have substantial numbers of outliers, hypothesis testing of 

data with these characteristics without appropriate transformations is inadvisable (Helsel and Hirsch, 2002). Therefore, 

nonparametric statistical tests were used in this investigation. 

There is slightly decreased power for the statistical tests for 

normally distributed data (Helsel and Hirsch, 2002). The loss 

of power, however, can be far greater when false assumptions 

of normality are made and parametric methods are erroneously employed (Zar, 1974). Two-way analysis of variance 

(ANOVA) of ranked data was used to simultaneously test for 

differences among concentrations and yields of constituents 

at different sites, and for differences between growing and 

nongrowing seasons. All statistical tests were used to compare 

mean ranks and median ranks. The null hypotheses (Ho

) and 

alternate hypotheses (HA) can be stated in the form shown 

below, using nitrogen concentration as an example.

Ho1 There is no difference between growing and 

nongrowing seasons regarding the effects on the 

concentration of nitrate as nitrogen (NO3-N) 

(significance level=0.05).

Ha1 There is a difference between growing and 

nongrowing seasons regarding the effects on the 

concentration of nitrate as nitrogen (NO3-N) 

(significance level=0.05).

Ho2 There is no difference among the six streams in 

concentration of nitrate as nitrogen (NO3-N) 

(significance level=0.05).

Ha2 There are differences among the six streams in 

concentration of nitrate as nitrogen (NO3-N) 

(significance level=0.05).

The same set of null and alternate hypotheses were 

applied to concentrations and yields of all phosphorus and 

nitrogen species measurements, as well as to total suspended 

solids measurements and to bacterial-density measurements. 

The Tukey multiple comparison test of ranked data was used 

to conduct pair-wise comparisons of concentrations and yields 

of constituents at different sites. Here, each null hypothesis states that there is no difference between a given pair 

of streams in concentration of a water-quality characteristic 

(for example, NO3-N). Precipitation, water-quality data, and 

streamflow data were used to calculate loads of total nitrogen 

and phosphorus for the storms monitored for the entire period 

of record and for an annual-average basis. In this method, 

measured concentrations of constituents and measurements 

of streamflow during base flow and stormflow were used to 

directly calculate the mass loads of nitrogen and phosphorus 

species during sampling events. These load values were then 

extrapolated over the entire period of record by relating runoff 

to precipitation and calculating the amount of runoff during 

the period of record. Event-mean concentrations of chemical species were then used with the calculated runoff totals to 

determine total and average annual loads for each chemical 

constituent. The load during base flow was then separated 

from total load, and the difference between those was calculated as runoff load. The method also was applied separately to 

events monitored during growing and nongrowing seasons.

The first step was to determine the event mean concentrations of total nitrogen and total phosphorus for each storm 

sampling event using

(6)

where

EMC = event mean concentration of the 

water-quality characteristic of interest 

(total nitrogen or total phosphorus), in 

milligrams per liter, for a storm sampling 

event;

n = number of water-quality measurements 

made during the event;

n n

i=1 i=1
22 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

Ci = concentration of the water-quality 

characteristic of interest, in milligrams per 

liter, for measurement I, and 

Di = streamflow value at the time of the waterquality measurement i.

The second step was to determine the event total flow 

during the storm. This calculation, which includes streamflow 

from the beginning of precipitation to the end of event monitoring, and the attenuating flow as the stream returned to base 

flow (assuming no further precipitation), was made using

(7)

where

ETF = event total flow, in cubic feet; 

v = number of stream discharge measurements; 

and

t

i+1-ti = time elapsed between two discharge 

measurements, in seconds.

The total mass of the water-quality characteristic was 

then calculated for each storm event:

TMe = EMC * ETF * f , (8)

where

TMe = total mass of the water-quality 

characteristic for storm event e, in 

pounds and

f = conversion factor to convert mass from 

milligrams to pounds.

Base-flow mass was then calculated and subtracted from 

the total mass of each water-quality characteristic for each 

event to determine runoff mass values:

BFMe = Cbf * Dbf * g , (9)

SFMe = TMe - BFMe , (10)

where

BFMe = base-flow mass of the water-quality 

characteristic of interest for storm event e;

Cbf = concentration of the water-quality 

characteristic of interest, in milligrams per 

liter;

Dbf = base-flow discharge value, in cubic feet per 

second;

g = conversion factor to convert mass from 

milligrams to pounds and liters to cubic 

feet; and 

i=1

v

SFMe = mass of the water-quality characteristic of 

interest attributed to runoff for event e.

Mass of the water-quality characteristic for the entire 

period of record was then calculated by dividing the event 

mass by the fraction of precipitation in the period of record 

represented by the storm events. This was done for total mass, 

runoff mass, and base-flow mass using

(11)

(12)

(13)

where

TMpr = total mass of the water-quality 

characteristic for the entire period of 

record during which water-quality and 

streamflow were monitored;

x = number of storms monitored;

Ppr = total precipitation recorded during 

the period of record, in inches, at the 

meteorologic station closest to the 

monitoring site; and 

Pe = total precipitation during each storm, 

in inches, recorded at the meteorologic 

station closest to the monitoring site.

Annual load rates were then calculated by expressing the 

total mass on an annual basis:

TMyr = TMpr * (365/PR) , (14)

BFMyr = BFMpr * (365/PR) , (15)

SFMyr = SFMpr * (365/PR) , (16)

where

TMyr = total mass of the water-quality 

characteristic per year;

BFMyr = base-flow mass of the water-quality 

characteristic per year;

SFMyr = runoff mass of the water-quality 

characteristic per year; and

PR = the period of record, in days.

e=1 e=1

x x

e=1 e=1

x x

e=1 e=1

x x
Relations of Water Quality to Streamflow, Season, and Land Development 23

Annual yields were then calculated by dividing total mass 

load values by the area of the subbasins.

Relations of Water Quality to 

Streamflow, Season, and Land 

Development

Variability of concentrations and yields of nutrient species as a result of land-use patterns was observed by using 

boxplots and nonparametric statistical methods. Hydrologic 

conditions and season (growing and nongrowing) were also 

explored as explanatory variables.

Water-Quality Data

Concentrations and yields of water-quality constituents 

differed among the six sites during base-flow and stormflow 

conditions. Concentrations and yields also differed between 

the growing and nongrowing seasons. Summary statistics for 

all water-quality data collected are shown in appendix 1. (A 

complete listing of water-quality data is available upon request 

from the U.S. Geological Survey, New Jersey Water Science 

Center. Inclusion of the complete data set was not feasible due 

to its large volume.) All data were subjected to rank transformation because hydrologic data are non-normally distributed.

Results of all ANOVA and Tukey statistical testing are 

reported in one table (table 7), which contains the results of 

all hypotheses testing to determine whether concentrations or 

yields of specific water-quality characteristics vary in conjunction with land-use patterns and season, during storms and during base flow. The first two columns of the table identify the 

water-quality constituent and hydrologic conditions (stormflow or base flow). The next three columns show whether the 

null hypotheses were accepted or rejected. The null hypotheses 

are (1) differences in the value of the water-quality characteristic during the growing and the non-growing seasons are not 

significant, (2) differences in the value of the water-quality 

characteristic among the six sites are not significant, and (3) 

the amount of interaction between the categories (season and 

site) is not significant. The significance level for all analyses was set at α = 0.05. The remainder of the table shows 

the results of the Tukey test, which is a multiple comparison 

technique used to test for significant differences between each 

possible pair of subgroups after an ANOVA null hypothesis 

has been rejected. The result of Tukey analysis is to rank (lowest to highest) the six sites in terms of the mean value of the 

constituent being evaluated. In table 7, the letters A through F 

are used to designate this ranking. In many cases, one or more 

pairs of sites do not demonstrate significant differences in the 

value of the constituent (for example, concentration of total 

nitrogen), and those sites receive the same letter. This same 

ranking and lettering designation is used in the box plot figures 

that follow in this section.

Nitrogen

Elevated concentrations of nitrogen species can degrade 

the quality of surface water as a resource (for drinking water 

and recreation) and as a habitat. Excess nitrogen can cause 

eutrophic conditions to occur in lakes and rivers, including 

excessive algal growth, reduced light below the water surface, 

depleted dissolved oxygen, and subsequent death of aquatic 

plant life, benthic organisms, and vertebrates.

Sources of nitrogen include atmospheric deposition, 

fixation by leguminous plants, animal waste, discharge from 

industry and sewage-treatment plants, discharge from individual septic systems, and commercial fertilizers applied to 

farmland, residential properties, and commercial properties. 

The relative importance of nitrogen sources was evaluated by 

Vitousek and others (1997), who estimated that, on an annual 

basis, 90 to 140 teragrams (tg) of nitrogen are fixed globally 

by natural processes (bacterial activity and lightening), 140 tg 

are fixed by human activities, and 40 tg are mobilized by 

human activities. Vitousek and others (1997) projected a continuing increase in human-mediated contribution, especially 

in developing countries where amending soil with additional 

nitrogen is a rapid, inexpensive way to substantially increase 

crop yields. The long-term consequences of this constantly 

increasing load of fixed nitrogen to the nitrogen cycle are not 

known; however, the increase in eutrophication of streams, 

lakes and estuaries is a certainty.

Nitrogen species as percentages of total nitrogen in 

base flow and stormflow samples are summarized in table 8. 

Generally, the organic fraction tended to account for a higher 

percentage of total nitrogen in stormflow than in base-flow 

samples. Nitrite represented a minor fraction of total nitrogen 

in most samples, regardless of the site sampled, season, or 

hydrologic conditions. Nitrate was the most abundant species 

in most samples, and ammonia generally represented about 3 

to 6 percent of total nitrogen.

Total Nitrogen

The sum of organic and inorganic species of nitrogen is 

reported as total nitrogen in units of micrograms per liter as 

N. In this investigation both filtered and unfiltered samples 

were analyzed for total nitrogen. The total nitrogen concentration did not differ significantly between filtered and unfiltered 

samples and was represented by the following linear relation:

(total N, filtered) = 0.95 (total N, unfiltered), R2 = 0.99 (17)

In cases where only results from filtered samples were 

obtained, the value for the unfiltered sample was estimated by 

using this relation. Therefore, all total nitrogen concentrations 

are reported as unfiltered values, after applying the appropriate 

correction (dividing by 0.95) to total nitrogen concentrations 

determined for filtered samples.
24 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07 Table 7. Results of statistical tests to determine whether constituent concentrations and yields differ among sites during growing and nongrowing seasons, lower Delaware River Basin, New Jersey.—Continued [ Letters A through F designate the results of the Tukey test, which ranks (lowest to highest) the six sites in terms of the mean value of the parameter being evaluated. Where one or more pairs of sites do not demonstrate significant differences in the value of the characteristic, those sites receive the same letter; o-Phosphate, ortho phosphate; TSS, total suspended solids; conc., concentrations; E coli, Escherichia coli; site locations are shown in figure. 2; all significance levels are p = 0.05] Analysis of variance result Tukey Test 2, growing season Tukey Test, nongrowing season Constituent1 Condition 3Ho1

4Ho2

5Ho3 UND1 UND2 AGR2 AGR1 URB1 URB2 UND1 UND2 AGR2 AGR1 URB1 URB2

Total nitrogen conc. Base flow NR

R NR BC

A

E

D

B CD BC

A

E

D

B CD

Total nitrogen conc. Stormflow NR

R NR

B

A

E

D

C BC

B

A

E

D

C BC

Total nitrogen yield Base flow

R

R NR

B

A

C

B

B

B BC

A

D C 

B

B

Total nitrogen yield Stormflow NR

R NR

B

A

E CD

D BC

B

A

E CD

D BC

Organic nitrogen conc. Base flow NR

R NR

A

A

B AB

A

A

A

A

B AB

A A 

Organic nitrogen conc. Stormflow R 

R NR AB

A

D CD

C BC AB

A

C BC 

B AB

Organic nitrogen yield Base flow R 

R NR ABC

A

C AB BC ABC

A

A

B AB AB

A

Organic nitrogen yield Stormflow R 

R NR

B

A

C BC

C BC

B

A

B B 

B

B

Ammonia conc. Base flow NR

R NR AB

A

B AB

C AB AB

A

B AB

C AB 

Ammonia conc. Stormflow R 

R NR AB

A

E CD DE BC AB

A

C BC 

C

B

Ammonia yield Base flow

R

R NR AB

A

C BC

D ABC

A

A

A A 

A

A

Ammonia yield Stormflow R 

R NR

B

A

D

C

D BC AB

A CD BCD 

D BC

Nitrate-N conc. Base flow NR

R NR

C

A

E

D

B CD

C

A

E

D

B CD 

Nitrate-N conc. Stormflow R 

R NR

B

A

D

C

B

B

B

A

C C 

B

B

Nitrate-N yield Base flow

R

R NR

B

A

C

B

B

B

C

A

E D 

B

C

Nitrate-N yield Stormflow R 

R NR

B

A

D

C

C BC

B

A

D

C BC

B

Total phosphorus conc. Base flow NR

R NR ABC

A CD BCD

D AB ABC

A CD BCD

D AB

Total phosphorus conc. Stormflow R 

R

R

B

A

D

D

D

C

A

A

B B 

B

A

Total phosphorus yield Base flow NR

R NR AB

A BC ABC

C AB AB

A BC ABC

C AB

Total phosphorus yield Stormflow R 

R NR

B

A DE CD

E BC AB

A CD BCD

D BC

o-Phosphate conc. Base flow NR NR NR

A

A

A

A

A

A

A

A

A

A

A

A

o-Phosphate conc. Stormflow R 

R NR

A

A

C

A AB

B

A

A

B A 

A

A

o-Phosphate yield Base flow NR NR NR AB

A

B AB AB AB AB

A

B AB AB AB

o-Phosphate yield Stormflow NR

R NR

B

A

D

B CD BC

B

A

D

B CD BC

TSS conc. Base flow NR

R NR AB

A AB

A

B

A AB

A AB

A

B

A

TSS conc. Stormflow NR

R NR

B

A

C

C

C

B

B

A

C

C

C

B

TSS yield Base flow NR

R NR AB

A AB

A

B

A AB

A AB

A

B

A
Relations of Water Quality to Streamflow, Season, and Land Development 25

Table 7. Results of statistical tests to determine whether constituent concentrations and yields differ among sites during growing and nongrowing seasons, lower Delaware River Basin, New Jersey.—Continued[ Letters A through F designate the results of the Tukey test, which ranks (lowest to highest) the six sites in terms of the mean value of the parameter being evaluated. Where one or more pairs of sites do not demonstrate significant differences in the value of the characteristic, those sites receive the same letter; o-Phosphate, ortho phosphate; TSS, total suspended solids; conc., concentrations; E coli, Escherichia coli; site locations are shown in figure. 2; all significance levels are p = 0.05]

Analysis of variance result Tukey Test 2, growing season Tukey Test, nongrowing season

Constituent1 Condition 3Ho1 4Ho2 5Ho3 UND1 UND2 AGR2 AGR1 URB1 URB2 UND1 UND2 AGR2 AGR1 URB1 URB2

TSS yield Stormflow NR R NR B A D D D BC B A D D D BC

Fecal coliform conc. Base flow R R NR AB A C AB BC A AB A C AB BC A

Fecal coliform conc. Stormflow R R R A A C AB BC AB A AB C A B AB

Fecal coliform yield Base flow NR R NR AB A C AB BC AB AB A C AB BC AB

Fecal coliform yield Stormflow R R NR AB A C B C BC A A C A B AB

E. Coli conc. Base flow NR R NR AB A C AB BC AB AB A C AB BC AB

E. Coli conc. Stormflow R R R A A C AB BC AB A A C A B AB

E. Coli yield Base flow NR R NR AB A C A BC A AB A C A BC A

E. Coli yield Stormflow R R NR AB A D B CD BC A A C A BC AB

1All concentrations and yield data were rank-transformed before statistical analyses were performed.2Tukey test results: sites assigned the same letter are not statistically different (α=0.05) in constituent concentration or yield.3Ho1: Null hypothesis, no difference between growing and nongrowing seasons (NR=null hypothesis not rejected; R=null hypothesis rejected).4Ho2: Null hypothesis, no difference among sites.5Ho3: Null hypothesis, no interaction between explanatory variables (seasons and sites).
26 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

Box plots for total nitrogen concentrations during base 

flow and stormflow in growing and nongrowing seasons are 

shown in figure 11. ANOVA and Tukey test results also are 

shown in table 7. Median total nitrogen concentrations were 

significantly higher in water samples from agricultural sites 

than from all other sites. For base-flow samples, the median 

concentrations (Appendix 1) for sites AGR1 and ARG2 are 

1,347 and 7,809 μg/L as N, respectively, substantially greater 

than the highest median concentrations in samples from 

undeveloped sites (727 μg/L as N, UND1) and urban sites 

(879 μg/L, URB2). Tukey test results show that total nitrogen 

concentrations are greater for AGR2 than for any other site 

under all flow and seasonal conditions. Concentrations of total 

nitrogen in samples from AGR1 were significantly higher than 

those at both undeveloped sites under all conditions. They also 

were higher than those at URB1 during stormflow, but not 

during baseflow, where Tukey analysis could not distinguish 

between total nitrogen concentrations in samples from sites 

AGR1 and URB2.

There is a large difference in total nitrogen concentration 

between sites AGR1 and AGR2 (fig. 11). This may be partially 

explained by the greater percentage of farmland in the basin 

upstream from AGR2 (76.6 percent compared to 55.4 percent 

for AGR1). The larger percentage of wetlands in the AGR1 

basin (18.6 percent compared to 6.2 percent for the AGR2 

basin) may help to attenuate nitrogen before it reaches the 

stream. The third difference observed between these two sites 

is that cattle were seen near and in Alloway Creek (AGR2) but 

not Blacks Creek (AGR1) during sampling events. The larger 

basin area for AGR1 also may serve to distribute the loads 

over a longer period of time, resulting in a decrease in the 

maximum and mean concentrations.

Land-use percentages for the two urban sites were similar 

(69.2 and 73.7 percent urban land use for URB1 and URB2, 

respectively). Percentages of the other land-use categories for 

these two basins also were similar. Total nitrogen concentrations were not significantly different (p = 0.05) between these 

two sites during stormflow, but concentrations in samples from 

URB2 collected during base flow in the growing and nongrowing seasons were slightly greater than those from URB1.

The basin upstream from UND2 is almost entirely forest 

and wetlands and has total nitrogen concentrations significantly lower than any other site. UND1 has concentrations 

similar to those of the urban sites. This may be because UND1 

has a substantial (13.6 percent) amount of urban development, 

as well as some agriculture adjacent to the creek.

Yields of total nitrogen for the six sites follow a similar 

pattern to that of concentrations (fig. 12). The total nitrogen 

yield for AGR2 was significantly greater than that for all other 

sites, and the yield for UND2 was lower than that for all other 

sites. Yields in base flow for the other four sites were not significantly different during the growing season but were greater 

for AGR1 than for the urban and undeveloped basins during 

the nongrowing season. Yields for AGR1 were greater than 

those of the undeveloped basins during growing and nongrowing seasons but were not distinguishable from those of the two 

urban basins.

Nitrite Plus Nitrate

Nitrite represents a minor percentage (about 1 percent 

in most cases) of total nitrogen concentrations in all water 

samples analyzed from all sites. Nitrite is an intermediate 

species in the biological nitrification part of the nitrogen cycle. 

Nitrosomonas are bacteria that oxidize ammonia to nitrite, and 

Nitrobacter are bacteria that further oxidize nitrite to nitrate. 

Therefore, nitrite is not considered a stable species under environmental conditions, and the low concentrations observed 

during this investigation are not surprising. Concentrations of 

nitrite were significantly higher in samples from site AGR2 

than in samples from any other site, and samples from UND1 

and UND2 tended to have lower concentrations than those 

from other sites. The same trend was observed for yields 

among the sites.

Nitrate accounts for most of the total nitrogen concentrations in most samples from all sites. Concentrations and yields 

of nitrate among the six sites are similar to those observed 

for total nitrogen (figs. 13 and 14). Concentrations in samples 

from site AGR2 were significantly higher than those for all 

other sites under base-flow and stormflow conditions in the 

growing and nongrowing seasons. The only exception is that 

the concentration for AGR2 cannot be distinguished from that 

for AGR1 during stormflow in the nongrowing season using 

the Tukey test, though it is evident from figure 13 that all 

values for AGR2 are greater than all values for AGR1. Nitrate 

concentrations in samples from site UND2, with a 99-percent 

undeveloped basin, are significantly lower than concentrations 

in samples from all other sites. Concentrations for site UND1 

are more similar to those for the urban sites than those for 

site UND2. This is probably because much of the urban and 

agricultural land in the basin upstream from UND1 is clustered near the stream; thus, much of the runoff and base flow 

reaching UND1 has passed through land uses that contribute 

nitrate to surface water.

Nitrate yields were significantly higher in samples from 

AGR2 than from any other site under all conditions. During 

base flow in the nongrowing season, yields at AGR1 were 

significantly higher than for both undeveloped and both urban 

samples.

Table 8. Mean percentages of total nitrogen in unfiltered 

water samples represented by four nitrogen species for six 

streams in the lower Delaware River Basin, New Jersey.

[Values do not sum to 100 percent due to rounding]

Hydrologic

condition

Percent of total nitrogen concentration

Nitrite Nitrate Organic N Ammonia

Base flow 0.8 85 11 3.5

Stormflow 1 61 32 5.6
Relations of Water Quality to Streamflow, Season, and Land Development 27

AGR1 AGR2 UND1 UND2 URB1 URB2

104

GROWING SEASON

103

102

D E B A C BC

STORMFLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

104

GROWING SEASON

CONCENTRATION OF TOTAL NITROGEN, IN MICROGRAMS PER LITER

103

102

D E BC A B CD

BASE FLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

104

NONGROWING SEASON

103

102

D E B A C BC

AGR1 AGR2 UND1 UND2 URB1 URB2

104

NONGROWING SEASON

103

102

D E BC A B CD

SITE SITE

A,B–Differing letters indicate significant differences in mean values, according to 

the Tukey multiple-comparison test 

MONITORING SITES

Agricultural

 AGR1, Blacks Creek near Chesterfield, New Jersey

 AGR2, Alloway Creek near Watson Corner, New Jersey

Undeveloped

 UND1, Lahaway Creek Tributary near Prospertown, New Jersey

 UND2, Gravelly Run at Laurel Lake, New Jersey

Urban

 URB1, Cooper River at Route 561 at Haddonfield, New Jersey

 URB2, South Branch Big Timber Creek Tributary at Grenloch, New Jersey

EXPLANATION

Number of observations

Outlier data value more than 

1.5 times the interquartile range 

outside the quartile

90th percentile

75th percentile

Median

25th percentile

10th percentile

(13)

(7)

(4)

(10)

(6)

(5)

(7) (21)

(28) (30)

(22)

(32)

(28)

(4)

(4)

(2)

(3)

(3)

(2)

(18)

(16) (12)

(16)

(6)

(11)

Figure 11. Distributions of total nitrogen concentrations in unfiltered water samples collected during base flow and stormflow in the 

growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 2002–07.
28 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

AGR1 AGR2 UND1 UND2 URB1 URB2

CD E B A D BC

STORMFLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

102

AREA-NORMALIZED LOAD (YIELD) OF TOTAL NITROGEN, IN POUNDS PER DAY PER SQUARE MILE

101

100

B C B A B B

BASE FLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

CD E B A D BC

AGR1 AGR2 UND1 UND2 URB1 URB2

C D BC A B B

SITE SITE

A,B–Differing letters indicate significant differences in mean values, according to 

the Tukey multiple-comparison test 

MONITORING SITES

Agricultural

 AGR1, Blacks Creek near Chesterfield, New Jersey

 AGR2, Alloway Creek near Watson Corner, New Jersey

Undeveloped

 UND1, Lahaway Creek Tributary near Prospertown, New Jersey

 UND2, Gravelly Run at Laurel Lake, New Jersey

Urban

 URB1, Cooper River at Route 561 at Haddonfield, New Jersey

 URB2, South Branch Big Timber Creek Tributary at Grenloch, New Jersey

EXPLANATION

Number of observations

Outlier data value more than 

1.5 times the interquartile range 

outside the quartile

90th percentile

75th percentile

Median

25th percentile

10th percentile

(13)

10-1

10-2

10-3

102

101

100

10-1

10-2

10-3

102

101

100

10-1

10-2

10-3

GROWING SEASON GROWING SEASON

NONGROWING SEASON NONGROWING SEASON

102

101

100

10-1

10-2

10-3

(7)

(4)

(10)

(6)

(5)

(7)

(21)

(28)

(30) (22)

(32) (28)

(4)

(4)

(2)

(3)

(3)

(2)

(19)

(16)

(12)

(16)

(12)

(10)

Figure 12. Distributions of area-normalized loads (yields) of total nitrogen in unfiltered water samples collected during base flow and 

stormflow in the growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 2002–07.
Relations of Water Quality to Streamflow, Season, and Land Development 29

AGR1 AGR2 UND1 UND2 URB1 URB2

C D B A B B

STORMFLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

104

CONCENTRATION OF NITRATE AS NITROGEN, IN MICROGRAMS PER LITER

103

102

D E C A B CD

BASE FLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

C C B A B B

AGR1 AGR2 UND1 UND2 URB1 URB2

D E C A B CD

SITE SITE

A,B–Differing letters indicate significant differences in mean values, according to 

the Tukey multiple-comparison test 

MONITORING SITES

Agricultural

 AGR1, Blacks Creek near Chesterfield, New Jersey

 AGR2, Alloway Creek near Watson Corner, New Jersey

Undeveloped

 UND1, Lahaway Creek Tributary near Prospertown, New Jersey

 UND2, Gravelly Run at Laurel Lake, New Jersey

Urban

 URB1, Cooper River at Route 561 at Haddonfield, New Jersey

 URB2, South Branch Big Timber Creek Tributary at Grenloch, New Jersey

EXPLANATION

Number of observations

Outlier data value more than 

1.5 times the interquartile range 

outside the quartile

90th percentile

75th percentile

Median

25th percentile

10th percentile

(13)

101

104

103

102

101

10 10 0 0

104

103

102

101

100

104

103

102

101

100

GROWING SEASON GROWING SEASON

NONGROWING SEASON NONGROWING SEASON

(7)

(4)

(10)

(6)

(5)

(6)

(21)

(28) (30)

(22)

(32)

(22)

(4)

(4)

(2)

(3)

(3)

(2)

(19)

(15)

(12)

(16)

(6)

(11)

Figure 13. Distributions of nitrate concentrations in unfiltered water samples collected during base flow and stormflow in the growing 

and nongrowing seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 2002–07.
30 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

AGR1 AGR2 UND1 UND2 URB1 URB2

C D B A C BC

STORMFLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

102

AREA-NORMALIZED LOAD OF NITRATE AS NITROGEN, IN POUNDS PER DAY PER SQUARE MILE

101

100

B C B A B B

BASE FLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

C D B A BC B

AGR1 AGR2 UND1 UND2 URB1 URB2

D E C A B C

SITE SITE

A,B–Differing letters indicate significant differences in mean values, according to 

the Tukey multiple-comparison test 

MONITORING SITES

Agricultural

 AGR1, Blacks Creek near Chesterfield, New Jersey

 AGR2, Alloway Creek near Watson Corner, New Jersey

Undeveloped

 UND1, Lahaway Creek Tributary near Prospertown, New Jersey

 UND2, Gravelly Run at Laurel Lake, New Jersey

Urban

 URB1, Cooper River at Route 561 at Haddonfield, New Jersey

 URB2, South Branch Big Timber Creek Tributary at Grenloch, New Jersey

EXPLANATION

Number of observations

Outlier data value more than 

1.5 times the interquartile range 

outside the quartile

90th percentile

75th percentile

Median

25th percentile

10th percentile

(13)

10-1

102

101

100

10-1

10-2 10-2

102

101

100

10-1

10-2

102

101

100

10-1

10-2

GROWING SEASON GROWING SEASON

NONGROWING SEASON NONGROWING SEASON

(7)

(4)

(10)

(6)

(5)

(6)

(21)

(28)

(30)

(22) (32)

(22)

(4)

(4)

(2)

(3)

(3)

(2)

(19)

(15) (12)

(16)

(6)

(11)

Figure 14. Distributions of area-normalized loads (yields) of nitrate in unfiltered water samples collected during base flow and 

stormflow in the growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 2002–07.
Relations of Water Quality to Streamflow, Season, and Land Development 31

Yields at UND2 are significantly lower than at any other 

site. As with nitrate concentrations, nitrate yields at UND1 are 

more similar to those for the urban sites than to those for the 

other undeveloped site.

Ammonia

Ammonia (NH3) is the most reduced nitrogen species 

found in surface water and persists only under anaerobic 

(reducing) conditions (National Research Council, 1979). 

Concentrations are expressed as milligrams per liter NH3 as N. 

Application of ammonium-based fertilizers and effluents from 

sewage-treatment plants can contribute substantial amounts 

of ammonia to surface water, as is the case for the Kansas 

River (Rasmussen and Christensen, 2005). Untreated domestic 

wastewater typically contains 12 to 50 mg/L NH3- as N (Metcalf and Eddy Inc., 1979). Bacterial decomposition of organic 

matter under reducing (anaerobic) conditions in bottom sediments also contributes ammonia to surface water.

Ammonia in sufficiently high concentrations is toxic 

to most aquatic organisms. Toxicity levels are affected by 

dissolved oxygen concentrations, temperature, pH, previous 

acclimation to ammonia, carbon dioxide concentrations, and 

the presence of other toxic compounds (U.S. Environmental Protection Agency, 1991). Ammonia did not constitute a 

substantial percentage of the total nitrogen concentrations or 

loads for the six streams; typically, ammonia constituted 3 to 6 

percent. Box plots in figure 15 show that there is no clear relation between land-use patterns and ammonia concentration. 

Perhaps most notably, concentrations in samples from URB1 

during base flow in the growing and nongrowing seasons were 

significantly higher than those from any other site. During 

stormflow, site UND2 had significantly lower concentrations 

of ammonia than either agricultural or urban site, and ammonia concentrations for UND2 could not be distinguished from 

those in samples from the other undeveloped site (UND1).

Yields at site URB1 were significantly higher than those 

at any other site during the growing season, but yields were 

homogeneous among all sites during base flow in the nongrowing season (fig. 16). As with concentrations, yields of 

ammonia for UND2 were lower than those for any other site.

Concentrations and loads of ammonia appear to be 

elevated in both agricultural and urban land-use areas, compared with concentrations and loads for background sites 

(undeveloped sites UDN1 and UND2) in the lower Delaware 

River Basin. It is not clear from the data collected which landuse category contributed most to the ammonia loads, but for 

all sites, ammonia represents only a few percent of the total 

concentrations and yields of nitrogen.

Organic Nitrogen

Concentrations of organic nitrogen are calculated as the 

difference between total nitrogen and the sum of the concentrations of all inorganic nitrogen species (nitrate, nitrite, and 

ammonia). In water samples collected from the six sites in 

the lower Delaware River Basin organic nitrogen constituted 

a substantial fraction of the total nitrogen concentrations and 

loads (10–35 percent).

Sources of organic nitrogen in surface water include soil 

mineralization, algal and other aquatic plant growth, terrestrial plant residue, animal wastes, and decomposition of 

plant material. In surface water, organic nitrogen is present 

in amino acids, proteins, nucleic acids, and other biological 

macromolecules.

The molecular formula of algal protoplasm (Redfield 

stoichiometry) can be used to approximate the nitrogen content of organic matter (Redfield, 1958):

106 CO2

+16 NO3-+HPO4

2-+122 H2

O+18 H+ →> (18)

C106H263O110N16P1.

Thus, on a mass basis, organic matter in streams contains 

approximately 6.3 percent nitrogen. The sources, properties, 

and bioavailability of organic nitrogen in a stream are dependent upon the properties of suspended and dissolved organic 

matter. Sources of organic carbon can be classified as either 

autochthonous, contributed by in-stream processes such as 

decaying algal, plant, and animal tissues, or allochthonous, 

such as organic material in runoff from point and nonpoint 

sources (Gondar and others, 2008).

Organic nitrogen concentrations (fig. 17) were significantly higher in samples from site AGR2 collected during 

base flow than in those from the two undeveloped and the two 

urban sites but statistically indistinguishable from those in 

samples from site AGR1. There was no significant difference 

among concentrations in samples from undeveloped and urban 

sites. Yields of organic nitrogen did not have a clearly evident 

relation to land use; however, UND2, the least developed 

site, had significantly lower concentrations than all other sites 

during stormflow. Although site UND2 had the lowest organic 

nitrogen yield of all sites (fig. 18), the Tukey test did not distinguish among the sites with respect to land-use patterns.

Phosphorus

Phosphorus is an essential element for all organisms, 

and as a result, any excessive loads of phosphorus to surface 

water can lead to eutrophication. Phosphorus can be present in 

organic matter; however, generally the highest concentrations 

are present in inorganic forms (orthophosphate and polyphosphates). Application of inorganic fertilizers is one of the most 

important sources of phosphorus in surface waters (Mueller 

and others, 1995). 

It has been estimated that about 80 percent of lake and 

reservoir eutrophication is the result of excess phosphorus. About 10 percent of lake and reservoir eutrophication 

is related to nitrogen, and the other 10 percent of lake and 

reservoir eutrophication is related to other factors (Zhao, 

2004). Although phosphorus in natural water systems tends to 

be associated with the solid phase, adsorbed to sediment and 
32 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

AGR1 AGR2 UND1 UND2 URB1 URB2

CD E AB A DE BC

STORMFLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

103

CONCENTRATION OF AMMONIA AS NITROGEN, IN MICROGRAMS PER LITER

102

101

AB B AB A C AB

BASE FLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

BC C AB A C B

AGR1 AGR2 UND1 UND2 URB1 URB2

AB B AB A C AB

SITE SITE

A,B–Differing letters indicate significant differences in mean values, according to 

the Tukey multiple-comparison test 

MONITORING SITES

Agricultural

 AGR1, Blacks Creek near Chesterfield, New Jersey

 AGR2, Alloway Creek near Watson Corner, New Jersey

Undeveloped

 UND1, Lahaway Creek Tributary near Prospertown, New Jersey

 UND2, Gravelly Run at Laurel Lake, New Jersey

Urban

 URB1, Cooper River at Route 561 at Haddonfield, New Jersey

 URB2, South Branch Big Timber Creek Tributary at Grenloch, New Jersey

EXPLANATION

Number of observations

Outlier data value more than 

1.5 times the interquartile range 

outside the quartile

90th percentile

75th percentile

Median

25th percentile

10th percentile

(13)

103

102

101

100 100

103

102

101

100

103

102

101

100

GROWING SEASON GROWING SEASON

NONGROWING SEASON NONGROWING SEASON

(7)

(4)

(10)

(6) (5)

(7)

(21)

(30) (28)

(22) (32)

(28)

(4) (4) (2)

(3) (3)

(2)

(19)

(16)

(12) (16) (6)

(10)

Figure 15. Distributions of ammonia concentrations in unfiltered water samples collected during base flow and stormflow in the 

growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 2002–07.
Relations of Water Quality to Streamflow, Season, and Land Development 33

AGR1 AGR2 UND1 UND2 URB1 URB2

C D B A D BC

STORMFLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

102

AREA-NORMALIZED LOAD OF AMMONIA AS NITROGEN, IN POUNDS PER DAY PER SQUARE MILE

101

100

BC C AB A D ABC

BASE FLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

BCD CD AB A D BC

AGR1 AGR2 UND1 UND2 URB1 URB2

A A A A A A

SITE SITE

A,B–Differing letters indicate significant differences in mean values, according to 

the Tukey multiple-comparison test 

MONITORING SITES

Agricultural

 AGR1, Blacks Creek near Chesterfield, New Jersey

 AGR2, Alloway Creek near Watson Corner, New Jersey

Undeveloped

 UND1, Lahaway Creek Tributary near Prospertown, New Jersey

 UND2, Gravelly Run at Laurel Lake, New Jersey

Urban

 URB1, Cooper River at Route 561 at Haddonfield, New Jersey

 URB2, South Branch Big Timber Creek Tributary at Grenloch, New Jersey

EXPLANATION

Number of observations

Outlier data value more than 

1.5 times the interquartile range 

outside the quartile

90th percentile

75th percentile

Median

25th percentile

10th percentile

(13)

10-3

10-1

10-2

102

101

100

10-3

10-1

10-2

102

101

100

10-3

10-1

10-2

102

101

100

10-3

10-1

10-2

GROWING SEASON GROWING SEASON

NONGROWING SEASON NONGROWING SEASON

(7)

(4)

(10)

(6) (5)

(7)

(21)

(28)

(30)

(22)

(32)

(28)

(4)

(4) (2) (3) (3)

(2)

(19)

(16)

(12)

(16) (6)

(10)

Figure 16. Distributions of area-normalized loads (yields) of ammonia in unfiltered water samples collected during base flow and 

stormflow in the growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 2002–07.
34 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

AGR1 AGR2 UND1 UND2 URB1 URB2

CD D AB A C BC

STORMFLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

104

CONCENTRATION OF ORGANIC NITROGEN AS NITROGEN, IN MICROGRAMS PER LITER

103

101

AB B A A A A

BASE FLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

BC C AB A B AB

AGR1 AGR2 UND1 UND2 URB1 URB2

BC C AB A B AB

SITE SITE

A,B–Differing letters indicate significant differences in mean values, according to 

the Tukey multiple-comparison test 

MONITORING SITES

Agricultural

 AGR1, Blacks Creek near Chesterfield, New Jersey

 AGR2, Alloway Creek near Watson Corner, New Jersey

Undeveloped

 UND1, Lahaway Creek Tributary near Prospertown, New Jersey

 UND2, Gravelly Run at Laurel Lake, New Jersey

Urban

 URB1, Cooper River at Route 561 at Haddonfield, New Jersey

 URB2, South Branch Big Timber Creek Tributary at Grenloch, New Jersey

EXPLANATION

Number of observations

Outlier data value more than 

1.5 times the interquartile range 

outside the quartile

90th percentile

75th percentile

Median

25th percentile

10th percentile

(13)

10-1

GROWING SEASON GROWING SEASON

NONGROWING SEASON NONGROWING SEASON

100

102

104

103

101

10-1

100

102

104

103

101

10-1

100

102

104

103

101

10-1

100

102

(7) (3)

(10)

(6)

(5)

(7)

(21)

(28) (30)

(22)

(32)

(28)

(4) (4) (2)

(3)

(3)

(2) (19) (15)

(12)

(16)

(6) (10)

Figure 17. Distributions of organic nitrogen concentrations in unfiltered water samples collected during base flow and stormflow in 

the growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 2002–07.
Relations of Water Quality to Streamflow, Season, and Land Development 35

AGR1 AGR2 UND1 UND2 URB1 URB2

BC C B A C BC

STORMFLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

103

AREA-NORMALIZED LOAD OF ORGANIC NITRIGEN, IN POUNDS PER DAY PER SQUARE MILE

102

100

AB C ABC A BC ABC

BASE FLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

B B B A B B

AGR1 AGR2 UND1 UND2 URB1 URB2

AB B A A AB A

SITE SITE

A,B–Differing letters indicate significant differences in mean values, according to 

the Tukey multiple-comparison test 

MONITORING SITES

Agricultural

 AGR1, Blacks Creek near Chesterfield, New Jersey

 AGR2, Alloway Creek near Watson Corner, New Jersey

Undeveloped

 UND1, Lahaway Creek Tributary near Prospertown, New Jersey

 UND2, Gravelly Run at Laurel Lake, New Jersey

Urban

 URB1, Cooper River at Route 561 at Haddonfield, New Jersey

 URB2, South Branch Big Timber Creek Tributary at Grenloch, New Jersey

EXPLANATION

Number of observations

Outlier data value more than 

1.5 times the interquartile range 

outside the quartile

90th percentile

75th percentile

Median

25th percentile

10th percentile

(13)

10-2

GROWING SEASON GROWING SEASON

NONGROWING SEASON NONGROWING SEASON

10-1

101

103

102

100

10-2

10-1

101

103

102

100

10-2

10-1

101

103

102

100

10-2

10-1

101

(7)

(3)

(10)

(6)

(5)

(7)

(21)

(28)

(30) (22) (32)

(28)

(4)

(4) (2)

(3)

(3)

(2) (19)

(15) (12) (16)

(6)

(10)

Figure 18. Distributions of area-normalized loads (yields) of organic nitrogen in unfiltered water samples collected during base flow 

and stormflow in the growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 2002–07.
36 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

particulates, substantial mobility of phosphorus in groundwater has been demonstrated (Walter and others, 1999). Therefore, some dissolved phosphorus is expected in base flow 

(supplied by groundwater), whereas stormflow containing 

phosphorus-laden sediments is expected to have higher total 

phosphorus concentrations.

Phosphorus is introduced into lakes and streams from 

point and nonpoint sources. Nonpoint sources include natural decomposition of rocks and minerals, stormwater runoff, 

agricultural runoff, erosion and sedimentation, atmospheric 

deposition, and direct input by animals/wildlife. Point sources 

may include wastewater-treatment plants and permitted industrial discharges. In general, concentrations of phosphorus from 

nonpoint sources typically are significantly higher than those 

from point sources.

Because of its important role in the growth of algae 

and other aquatic plants, the trophic state of a freshwater 

body can be characterized by the phosphorus concentration 

(table 1). Lakes with total phosphorus concentrations less than 

0.010 mg/L are classified as oligotrophic. Lakes with phosphorus concentrations from 0.010 to 0.035 mg/L are indicative of 

mesotrophic lakes, and lakes with phosphorus concentrations 

exceeding 0.035 mg/L are classified as eutrophic (Mueller and 

Helsel, 1999).

Total Phosphorus

Concentrations of total phosphorus in base flow were 

generally lower than those in stormflow (fig. 19). This was 

expected because most phosphorus in a natural water system 

is transported in the solid phase (sediment, suspended sediment, and colloidal matter). There is a subtle relation between 

total phosphorus concentration and land use during base flow. 

The six sites can be grouped into two categories on the basis 

of mean (or median) base-flow total phosphorus concentrations. The two agricultural sites and one urban site (Cooper 

River, URB1) typically had base-flow concentrations of 0.4 

to 0.6 mg/L of total phosphorus as P, and the two undeveloped sites and one urban site (Big Timber Creek, URB2) 

had concentrations of 0.02 to 0.08 mg/L, about an order of 

magnitude lower. Higher concentrations of phosphorus for the 

agricultural sites compared to those for the undeveloped sites 

can be attributed to the well-characterized effect of agricultural land use. The difference in base-flow total phosphorus 

concentrations between the two urban streams is probably due 

to the long-term historical discharge of poorly treated domestic wastewater into the Cooper River but not into Big Timber 

Creek. Under stormflow conditions the same three streams 

(Cooper River, Alloway Creek, and Blacks Creek) had significantly higher concentrations of total phosphorus than the other 

streams.

Yields of total phosphorus during base flow are not 

clearly related to land use. The yield in base-flow samples 

from site URB1 was significantly greater than that for URB2, 

analogous to the relation for total phosphorus concentration. 

During stormflow, yields of total phosphorus were lower for 

the two undeveloped sites than for the urban and agricultural 

sites during growing and nongrowing seasons. The highest 

median yields were determined for URB1, which had significantly greater yields than URB2. It is clear from figures 19 and 

20 that high concentrations and yields of total phosphorus are 

associated with agricultural and urban land-use activities.

Orthophosphate

Concentrations of orthophosphate during base flow 

(fig. 21) are statistically indistinguishable among sites and 

between seasons. The low concentrations (typically 1–3 μg/L 

as P) indicate that orthophosphate is either not mobile or is 

conservative in the porous media underlying these streams 

and in the basins, or that there are no substantial sources of 

orthophosphate to the discharging groundwater (base flow). 

Concentrations of orthophosphate greater than 1 mg/ in 

surface water are often caused by groundwater (base flow) 

that contacted phosphate-rich natural deposits. For example, 

Wilson and others (1999) report concentrations of orthophosphate greater than 1 mg/L in groundwater discharging to the 

Tualatin River of northwest Oregon. Efforts to control phosphorus levels in that area of Oregon by decreasing agricultural 

and domestic wastewater inputs were not successful, and the 

principal source of phosphorus was found to be phosphatebearing vivianite (hydrated ferrous phosphate). The absence of 

orthophosphate in base flow (originating from groundwater) 

for all six streams in this study indicates that mineralogical 

sources are not substantial.

The stream with the most consistently elevated orthophosphate concentrations was Alloway Creek (AGR2); concentrations were an order of magnitude greater than those of 

the other streams during the growing and nongrowing seasons. 

This is most likely due to the presence of livestock in and 

near the stream. The orthophosphate is probably a biochemical byproduct of the organic phosphorus derived from cattle 

waste. The orthophosphate concentration for Cooper River 

(URB2) was sometimes higher than those for the other urban 

stream and the undeveloped streams, especially during the 

growing season. The cause for this is unknown.

Yields of orthophosphate for the pristine Gravelly Run 

(UND2) (fig. 22) tended to be lower than those for the other 

streams during base flow. Yields among the other streams were 

statistically indistinguishable. Yields during stormflow varied 

widely in most streams, making it impossible to statistically 

differentiate mean values. Yields for Alloway Creek (AGR2) 

were significantly higher than those of all other streams, and 

yields for the urban streams—Cooper River and South Branch 

Big Timber Creek—tended to be higher than those of the 

undeveloped streams—Lahaway Creek and Gravelly Run.

Ratios of Total Nitrogen to Total Phosphorus

The ratio of nitrogen to phosphorus in a surface-water 

body is an indicator of which nutrient is limiting. Phosphoruslimited conditions generally exist when the total-N to total-P 
Relations of Water Quality to Streamflow, Season, and Land Development 37

AGR1 AGR2 UND1 UND2 URB1 URB2

D D B A D C

STORMFLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

104

CONCENTRATION OF TOTAL PHOSPHORUS, IN MICROGRAMS PER LITER

103

101

BCD CD ABC A D AB

BASE FLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

B B A A B A

AGR1 AGR2 UND1 UND2 URB1 URB2

BCD CD ABC A D AB

SITE SITE

A,B–Differing letters indicate significant differences in mean values, according to 

the Tukey multiple-comparison test 

MONITORING SITES

Agricultural

 AGR1, Blacks Creek near Chesterfield, New Jersey

 AGR2, Alloway Creek near Watson Corner, New Jersey

Undeveloped

 UND1, Lahaway Creek Tributary near Prospertown, New Jersey

 UND2, Gravelly Run at Laurel Lake, New Jersey

Urban

 URB1, Cooper River at Route 561 at Haddonfield, New Jersey

 URB2, South Branch Big Timber Creek Tributary at Grenloch, New Jersey

EXPLANATION

Number of observations

Outlier data value more than 

1.5 times the interquartile range 

outside the quartile

90th percentile

75th percentile

Median

25th percentile

10th percentile

(13)

100

GROWING SEASON GROWING SEASON

NONGROWING SEASON NONGROWING SEASON

102

104

103

101

100

102

104

103

101

100

102

104

103

101

100

102

(7) (4)

(10)

(6)

(5)

(7)

(20)

(28)

(30) (32) (22)

(28)

(4)

(4)

(2) (3)

(3) (2)

(18)

(16)

(12)

(16) (7)

(11)

Figure 19. Distributions of total phosphorus concentrations in unfiltered water samples collected during base flow and stormflow in 

the growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 2002–07.
38 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

AGR1 AGR2 UND1 UND2 URB1 URB2

CD DE B A E BC

STORMFLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

103

AREA-NORMALIZED LOAD OF TOTAL PHOSPHORUS, IN POUNDS PER DAY PER SQUARE MILE

102

10-1

ABC BC AB A C AB

BASE FLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

BCD CD AB A D BC

AGR1 AGR2 UND1 UND2 URB1 URB2

ABC BC AB A C AB

SITE SITE

A,B–Differing letters indicate significant differences in mean values, according to 

the Tukey multiple-comparison test 

MONITORING SITES

Agricultural

 AGR1, Blacks Creek near Chesterfield, New Jersey

 AGR2, Alloway Creek near Watson Corner, New Jersey

Undeveloped

 UND1, Lahaway Creek Tributary near Prospertown, New Jersey

 UND2, Gravelly Run at Laurel Lake, New Jersey

Urban

 URB1, Cooper River at Route 561 at Haddonfield, New Jersey

 URB2, South Branch Big Timber Creek Tributary at Grenloch, New Jersey

EXPLANATION

Number of observations

Outlier data value more than 

1.5 times the interquartile range 

outside the quartile

90th percentile

75th percentile

Median

25th percentile

10th percentile

(13)

10-2

GROWING SEASON GROWING SEASON

NONGROWING SEASON NONGROWING SEASON

100

101

103

102

10-1

10-2

100

101

103

102

10-1

10-2

100

101

103

102

10-1

10-2

100

101

(7) (4)

(10)

(6) (5)

(7)

(20)

(28)

(30)

(22)

(32)

(28)

(4)

(4)

(3) (2) (3) (2)

(18)

(16)

(12)

(16) (7)

(11)

Figure 20. Distributions of area-normalized loads (yields) of total phosphorus in unfiltered water samples collected during base flow 

and stormflow in the growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 2002–07.
Relations of Water Quality to Streamflow, Season, and Land Development 39

AGR1 AGR2 UND1 UND2 URB1 URB2

A C A A AB B

STORMFLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

CONCENTRATION OF ORTHOPHOSPHATE AS PHOSPHORUS, IN MICROGRAMS PER LITER

103

101

A A A A A A

BASE FLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

A B A A A A

AGR1 AGR2 UND1 UND2 URB1 URB2

A A A A A A

SITE SITE

A,B–Differing letters indicate significant differences in mean values, according to 

the Tukey multiple-comparison test 

MONITORING SITES

Agricultural

 AGR1, Blacks Creek near Chesterfield, New Jersey

 AGR2, Alloway Creek near Watson Corner, New Jersey

Undeveloped

 UND1, Lahaway Creek Tributary near Prospertown, New Jersey

 UND2, Gravelly Run at Laurel Lake, New Jersey

Urban

 URB1, Cooper River at Route 561 at Haddonfield, New Jersey

 URB2, South Branch Big Timber Creek Tributary at Grenloch, New Jersey

EXPLANATION

Number of observations

Outlier data value more than 

1.5 times the interquartile range 

outside the quartile

90th percentile

75th percentile

Median

25th percentile

10th percentile

(13)

100

GROWING SEASON GROWING SEASON

NONGROWING SEASON NONGROWING SEASON

102

103

101

100

102

103

101

100

102

103

101

100

102

(7) (4)

(10) (6)

(5)

(7)

(21)

(28) (30)

(22)

(32)

(28)

(4) (2) (4) (3) (3)

(2) (19)

(16)

(12)

(16)

(6)

(11)

Figure 21. Distributions of orthophosphate concentrations in unfiltered water samples collected during base flow and stormflow in the 

growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 2002–07.
40 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

AGR1 AGR2 UND1 UND2 URB1 URB2

B D B A CD BC

STORMFLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

AREA-NORMALIZED LOAD OF ORTHOPHOSPHORUS, IN POUNDS PER DAY PER SQUARE MILE

101

10-1

AB B AB A AB AB

BASE FLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

B D B A CD BC

AGR1 AGR2 UND1 UND2 URB1 URB2

AB B AB A AB AB

SITE SITE

A,B–Differing letters indicate significant differences in mean values, according to 

the Tukey multiple-comparison test 

MONITORING SITES

Agricultural

 AGR1, Blacks Creek near Chesterfield, New Jersey

 AGR2, Alloway Creek near Watson Corner, New Jersey

Undeveloped

 UND1, Lahaway Creek Tributary near Prospertown, New Jersey

 UND2, Gravelly Run at Laurel Lake, New Jersey

Urban

 URB1, Cooper River at Route 561 at Haddonfield, New Jersey

 URB2, South Branch Big Timber Creek Tributary at Grenloch, New Jersey

EXPLANATION

Number of observations

Outlier data value more than 

1.5 times the interquartile range 

outside the quartile

90th percentile

75th percentile

Median

25th percentile

10th percentile

(13)

10-2

GROWING SEASON GROWING SEASON

NONGROWING SEASON

NONGROWING SEASON

100

101

10-1

10-2

100

101

10-1

10-2

100

101

10-1

10-2

100

(7)

(10) (4) (6) (5) (7) (21)

(28)

(30)

(22)

(32)

(28)

(4)

(4)

(2)

(3) (3) (2) (19)

(16)

(12)

(16)

(6) (11)

Figure 22. Distributions of area-normalized loads (yields) of orthophosphate in unfiltered water samples collected during base flow and 

stormflow in the growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 2002–07.
Relations of Water Quality to Streamflow, Season, and Land Development 41

ratio is greater than 20. Nitrogen is limited when the ratio is 

greater than 10, and for ratios between 20 and 10 either nutrient could be limiting (Ji, 2008). Light may be the limiting factor when both nitrogen and phosphorus are present in excess. 

The ratios of mean concentrations of nitrogen and phosphorus 

for the six sites during streamflow and base flow are listed 

in table 9, which also indicates which nutrient is likely to 

be limiting. The undeveloped stream Gravelly Run (UND2) 

is slightly nitrogen limiting during base flow but is neither 

nitrogen nor phosphorus limited during stormflow. Because 

of very low concentrations of both nutrients, Gravelly Run 

is not likely to undergo eutrophication under any conditions. 

The other undeveloped stream, Lahaway Creek (UND1), is 

slightly phosphorus limited but only under base-flow conditions. Because Lahaway Creek has relatively high concentrations of nitrogen for a stream in an undeveloped basin, 

additional phosphorus inputs may lead to eutrophic conditions. 

Both agricultural streams are highly phosphorus limited under 

base-flow conditions. Blacks Creek (AGR1) is neutral with 

respect to nutrient limitation under stormflow conditions, but 

Alloway Creek (AGR2) is nitrogen limited as a result of large 

phosphorus loads from livestock. Cooper River (URB1) is 

always nitrogen limited as a result of the large amounts of 

phosphorus (orthophosphate and total) in the stream under all 

flow conditions.

Eutrophication in estuarine water can be limited by the 

abundance of either phosphorus or nitrogen. Literature discussing this was summarized by Howarth and Marino (2006). 

Initially, phosphorus was thought to be more often limited, 

with carbon limitation also possible (Bartsch, 1972). However, 

as studies on the nature and causes of eutrophication were 

completed, it became increasingly clear that nitrogen is most 

often limited in estuaries. This finding has implications for 

streams in the lower Delaware River Basin, especially Alloway Creek and the Cooper River, which deliver substantial 

loads of nitrogen to the Delaware Bay.

Bacteria

Densities of fecal coliform bacteria, specifically enterococci strains and Escherichia coli (E. coli) bacteria, can be 

used as an indicator of contamination from fecal material. 

Many of the organisms can be harmful to human health. Fecal 

coliform bacteria reside in the intestinal tracts of mammals 

and birds where they symbiotically assist in the digestion process. Specifically, E. coli bacteria are most often found in the 

intestinal tracts of healthy cattle and other mammals. 

Quantitative fecal coliform data are reported as the most 

probable number (MPN) of coliform bacteria in 100 milliliters (mL) of water (American Public Health Association 

and others, 1999). The numerical criteria for FW2 streams, 

the classification of all stream reaches in this study, are 

“fecal coliform levels shall not exceed a geometric average of 200 MPN/100 mL nor should more than 10 percent 

of the samples collected during any 30-day period exceed 

400 MPN/100 mL” (New Jersey Department of Environmental Protection, 1998). The MPN is obtained by serially diluting 

a sample, usually in order-of-magnitude steps with several 

replicates at each dilution level, then counting the number 

of replicates at each level that contain a viable population of 

the organism of interest. A “positive” replicate is indicated 

by color change, gas evolution, cloudiness of the sample, or 

some other chemical or physical change that indicates the 

presence of a viable microbial population. The assumption 

is made that a detectable population can arise from a single 

viable individual. The numbers of positive replicates at the 

lowest three dilutions are used with a probability function 

to determine the MPN of viable organisms in the original 

sample. The MPN is itself an approximation and carries its 

own sources of error, which increase as the number of culture 

tubes decreases. The upper and lower bounds of the 95-percent 

confidence interval can differ by as much as a factor of 10 

(American Public Health Association and others, 1999). Large 

differences in MPN among samples, therefore, must be present 

before heterogeneity among samples can be demonstrated to 

be significant with respect to viable microbial agents, such as 

fecal coliform bacteria.

Alloway Creek (AGR2) generally had the highest 

concentrations and loads of fecal coliform bacteria among 

the six streams (fig. 23). This occurred during base flow and 

stormflow, and during growing and nongrowing seasons, 

probably the result of cattle in and around the stream. The 

other agricultural stream (Blacks Creek, AGR1) had relatively low concentrations of fecal coliform bacteria, compared 

Table 9. Ratios of nitrogen to phosphorus in six tributaries to 

the Delaware River, New Jersey, 2003–07. 

[N:P Ratio, ratio of the mean mass-concentration of total nitrogen as 

nitrogen to total phosphorus as phosphorus in water samples collected from 

the indicated stream in New Jersey during 2003–07; Limiting nutrient, the 

nutrient (total nitrogen or total phosphorus) which would be expected to 

change the rate of algal growth in a water body if its concentration was 

changed]

Stream N:P ratio Limiting nutrient

Base-flow conditions

AGR1 117 Phosphorus

AGR2 67.9 Phosphorus

UND1 22.5 Phosphorus

UND2 7.02 Nitrogen

URB1 5.42 Nitrogen

URB2 39.2 Phosphorus

Stormflow conditions

AGR1 15.5 Either

AGR2 6.73 Nitrogen

UND1 18 Either

UND2 12.6 Either

URB1 1.91 Nitrogen

URB2 14.1 Either
42 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

AGR1 AGR2 UND1 UND2 URB1 URB2

AB C A A BC AB

STORMFLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

CONCENTRATION OF FECAL COLIFORM BACTERIA, IN MOST PROBABLE NUMBER PER 100 MILLILITERS

106

102

AB C AB A BC A

BASE FLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

A C A AB B AB

AGR1 AGR2 UND1 UND2 URB1 URB2

AB C AB A BC A

SITE SITE

A,B–Differing letters indicate significant differences in mean values, according to 

the Tukey multiple-comparison test 

MONITORING SITES

Agricultural

 AGR1, Blacks Creek near Chesterfield, New Jersey

 AGR2, Alloway Creek near Watson Corner, New Jersey

Undeveloped

 UND1, Lahaway Creek Tributary near Prospertown, New Jersey

 UND2, Gravelly Run at Laurel Lake, New Jersey

Urban

 URB1, Cooper River at Route 561 at Haddonfield, New Jersey

 URB2, South Branch Big Timber Creek Tributary at Grenloch, New Jersey

EXPLANATION

Number of observations

Outlier data value more than 

1.5 times the interquartile range 

outside the quartile

90th percentile

75th percentile

Median

25th percentile

10th percentile

(13)

100

GROWING SEASON GROWING SEASON

NONGROWING SEASON

NONGROWING SEASON

104

105

101

103

106

102

100

104

105

101

103

106

102

100

104

105

101

103

106

102

100

104

105

101

103

(7)

(4)

(10)

(6)

(5)

(7) (22)

(28) (37)

(23)

(41)

(37)

(4)

(4) (2)

(3)

(3)

(2)

(20)

(15)

(12)

(17)

(10)

(15)

Figure 23. Distributions of fecal coliform bacteria concentrations in unfiltered water samples collected during base flow and 

stormflow in the growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 2002–07.
Relations of Water Quality to Streamflow, Season, and Land Development 43

to those in the Cooper River (URB1). Without livestock or 

urban sources, it is reasonable that only natural sources, such 

as wild birds and mammals, would contribute fecal coliform 

bacteria to the stream. High concentrations and loads of fecal 

coliform bacteria also were observed in samples from the 

Cooper River (URB1) and Big Timber Creek (URB2), the two 

urban streams. TMDLs have been established for both of these 

streams (New Jersey Department of Environmental Protection, 2004). The resulting waste allocations for these streams 

require a reduction of fecal coliform bacteria of 97 percent 

for Cooper River and 85 percent for Big Timber Creek, on 

the basis of a 400-colony forming units per 100 milliliters 

(CFU/100 mL) criteria. Sources of fecal coliforms were stated 

in the TMDL document as Canada geese and domestic pets. 

Strategies for reducing loads are given in Stormwater Phase II 

final rule (U.S. Environmental Protection Agency, 2000).

Loads of fecal coliform bacteria (fig. 24) were highest for 

Alloway Creek (AGR2), lowest for both undeveloped streams, 

and higher for Cooper River (URB1) than for the other urban 

stream (Big Timber Creek, URB2), following a pattern similar 

to that of the fecal coliform bacteria concentrations. Because 

most of the domestic wastewater-treatment plants have been 

removed from these streams, future management strategies 

will need to be based on controlling other coliform inputs, 

such as from livestock, domestic pets, and wildlife.

Total Suspended Solids

The term “total solids” refers to matter suspended or dissolved in water or wastewater and is related to both specific 

conductance and turbidity. Total solids (also referred to as 

total residue) is the term used for material left in a container 

after evaporation and drying of a water sample. Total solids includes both total suspended solids (TSS), the part of 

total solids retained in a filter with a specified pore size, and 

total dissolved solids, the part that passes through the filter 

(American Public Health Association and others, 1999). In 

most surface water, dissolved solids are a minor percentage 

of the suspended-solids mass, especially in stormflow. In base 

flow, however, dissolved solids and suspended solids can be 

approximately equal.

Method 2540D in American Public Health Association and others (1999) specifies the use of glass-fiber filter 

disks with a pore size of about 1.5 microns for separating 

suspended solids from the water sample. The water sample 

passes through the filter under negative pressure; then the 

filter is rinsed to remove dissolved solids and dried at 103 to 

105 degrees Celsius for at least 1 hour. The increase in filter 

mass (milligrams) divided by the sample volume (liter) is the 

TSS in milligrams per liter. TSS can include a wide variety of 

material, such as silt, decaying plant and animal matter, industrial wastes, and sewage. High concentrations of suspended 

solids can cause problems for stream health and aquatic life. 

For example, light penetration of water is reduced as TSS 

increases, which can reduce photosynthesis by algae and other 

aquatic plants, in turn reducing the production of oxygen in 

the water. Decreased water clarity from suspended solids also 

interferes with the ability of fish to catch prey and can clog the 

gills of fish, which leads to poor health or even death. Trace 

elements and organic compounds are often adsorbed onto suspended particles, which may be ingested by aquatic organisms, 

leading to toxicity. The USEPA does not provide a standard for 

TSS in drinking water but does specify that turbidity (largely 

resulting from suspended solids) may not exceed 5 nephelometric units (NTU) or 1 NTU for drinking-water systems 

using filtration. The New Jersey criterion for TSS is 40 mg/L 

for FW2-NT streams (New Jersey Department of Environmental Protection, 1998).

As expected, TSS concentrations and yields (figs. 25 

and 26) were low in samples collected during base flow from 

all six sites when compared with that in samples collected 

during stormflow. During stormflow, concentrations and 

loads increased but were highly variable for each stream, and 

relations between land use and TSS were not clearly evident. 

Gravelly Run (UND2) generally had the lowest loads suspended solids among the six streams. Loads for Cooper River 

(URB1) were significantly higher than those for Big Timber 

(URB2), the other urban stream, and statistically equivalent 

to the loads for two agricultural streams. Loads tended to be 

higher during the growing season than the nongrowing season. 

Concentrations and loads of suspended solids are important, as 

they affect the concentrations and loads of nutrient species as a 

result of adsorption and desorption.

Estimated Annual Yields of Total Nitrogen and 

Total Phosphorus

Annual loads of nitrogen and phosphorus species are 

listed in table 10 and are shown in figure 27. Gravelly Run 

had small loads of phosphorus when compared to loads for all 

other streams. Nearly all the phosphorus and nitrogen loads 

occurred during base flow. This is somewhat counterintuitive, 

given that phosphorus species are generally less mobile in 

groundwater than are nitrogen species. The low phosphorus 

loads can be explained by the lack of point- and nonpointsource inputs in this basin. The greater phosphorus loads 

from discharging groundwater could be related to naturally 

occurring phosphorus in geologic formations or from previous 

land-use activities. The Bridgeton Formation, which underlies Gravelly Run, contains phosphate nodules and may be a 

source. Base flow also is the principal source of nitrogen to 

Gravelly Run. This is reasonable, given the lack of surfacewater inputs and the possibility there are groundwater sources 

from outside this relatively pristine basin. The drainage basin 

of the other undeveloped site, Lahaway Creek, does contain 

some urban land use (13.6 percent) and agricultural land use 

(4.6 percent). The load of total phosphorus is about 3 times 

higher than that in the Gravelly Run Basin (fig. 20), and the 

load is relatively equally divided between base flow and runoff 

during the nongrowing season; however, during the growing 

season, total phosphorus load is substantially lower during 
44 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

AGR1 AGR2 UND1 UND2 URB1 URB2

B C AB A C BC

STORMFLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

AREA-NORMALIZED LOAD OF FECAL COLIFORM BACTERIA, IN MOST PROBABLE NUMBER 

PER DAY PER SQUARE MILE

1014

109

AB C AB A BC AB

BASE FLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

A C A A B AB

AGR1 AGR2 UND1 UND2 URB1 URB2

AB C AB A BC AB

SITE SITE

A,B–Differing letters indicate significant differences in mean values, according to 

the Tukey multiple-comparison test 

MONITORING SITES

Agricultural

 AGR1, Blacks Creek near Chesterfield, New Jersey

 AGR2, Alloway Creek near Watson Corner, New Jersey

Undeveloped

 UND1, Lahaway Creek Tributary near Prospertown, New Jersey

 UND2, Gravelly Run at Laurel Lake, New Jersey

Urban

 URB1, Cooper River at Route 561 at Haddonfield, New Jersey

 URB2, South Branch Big Timber Creek Tributary at Grenloch, New Jersey

EXPLANATION

Number of observations

Outlier data value more than 

1.5 times the interquartile range 

outside the quartile

90th percentile

75th percentile

Median

25th percentile

10th percentile

(13)

107

GROWING SEASON

GROWING SEASON

NONGROWING SEASON

NONGROWING SEASON

1011

1013

108

1010

1012

1014

109

107

1011

1013

108

1010

1012

1014

109

107

1011

1013

108

1010

1012

1014

109

107

1011

1013

108

1010

1012

(7)

(4)

(10)

(6)

(5)

(7) (22)

(28) (37)

(23)

(41)

(37)

(4)

(4) (2)

(3)

(3)

(2)

(20)

(15) (12)

(17)

(10)

(15)

Figure 24. Distributions of area-normalized loads (yields) of fecal coliform bacteria in unfiltered water samples collected during 

base flow and stormflow in the growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 

2002–07.
Relations of Water Quality to Streamflow, Season, and Land Development 45

AGR1 AGR2 UND1 UND2 URB1 URB2

C C B A C B

STORMFLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

CONCENTRATION OF TOTAL SUSPENDED SOLIDS, IN MILLIGRAMS PER LITER

103

101

A AB AB A B A

BASE FLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

C C B A C B

AGR1 AGR2 UND1 UND2 URB1 URB2

A AB AB A B A

SITE SITE

A,B–Differing letters indicate significant differences in mean values, according to 

the Tukey multiple-comparison test 

MONITORING SITES

Agricultural

 AGR1, Blacks Creek near Chesterfield, New Jersey

 AGR2, Alloway Creek near Watson Corner, New Jersey

Undeveloped

 UND1, Lahaway Creek Tributary near Prospertown, New Jersey

 UND2, Gravelly Run at Laurel Lake, New Jersey

Urban

 URB1, Cooper River at Route 561 at Haddonfield, New Jersey

 URB2, South Branch Big Timber Creek Tributary at Grenloch, New Jersey

EXPLANATION

Number of observations

Outlier data value more than 

1.5 times the interquartile range 

outside the quartile

90th percentile

75th percentile

Median

25th percentile

10th percentile

(13)

10-1

GROWING SEASON

GROWING SEASON

NONGROWING SEASON

NONGROWING SEASON

100

102

103

101

10-1

100

102

103

101

10-1

100

102

103

101

10-1

100

102

(7)

(4)

(10)

(6)

(5)

(7) (19)

(26)

(30)

(20) (32)

(28)

(4)

(4)

(2) (3)

(3)

(2)

(19)

(15) (12) (16)

(6)

(11)

Figure 25. Distributions of total suspended solids concentrations in unfiltered water samples collected during base flow and stormflow 

in the growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 2002–07.
46 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

AGR1 AGR2 UND1 UND2 URB1 URB2

D D B A D BC

STORMFLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

AREA-NORMALIZED LOAD OF TOTAL SUSPENDED SOLIDS, IN POUNDS PER DAY PER SQUARE MILE

106

102

A AB AB A B A

BASE FLOW

AGR1 AGR2 UND1 UND2 URB1 URB2

D D B A C BC

AGR1 AGR2 UND1 UND2 URB1 URB2

A AB AB A B A

SITE SITE

A,B–Differing letters indicate significant differences in mean values, according to 

the Tukey multiple-comparison test 

MONITORING SITES

Agricultural

 AGR1, Blacks Creek near Chesterfield, New Jersey

 AGR2, Alloway Creek near Watson Corner, New Jersey

Undeveloped

 UND1, Lahaway Creek Tributary near Prospertown, New Jersey

 UND2, Gravelly Run at Laurel Lake, New Jersey

Urban

 URB1, Cooper River at Route 561 at Haddonfield, New Jersey

 URB2, South Branch Big Timber Creek Tributary at Grenloch, New Jersey

EXPLANATION

Number of observations

Outlier data value more than 

1.5 times the interquartile range 

outside the quartile

90th percentile

75th percentile

Median

25th percentile

10th percentile

(13)

100

GROWING SEASON GROWING SEASON

NONGROWING SEASON NONGROWING SEASON

101

104

105

103

106

102

100

101

104

105

103

106

102

100

101

104

105

103

106

102

100

101

104

105

103

(7)

(4)

(10)

(6)

(5)

(7)

(4) (4)

(2) (3)

(3)

(2)

(19)

(15)

(12)

(16)

(6)

(11)

(19)

(26)

(30)

(20) (32)

(28)

Figure 26. Distributions of area-normalized loads (yields) of total suspended solids in unfiltered water samples collected during 

base flow and stormflow in the growing and nongrowing seasons at monitoring sites in the lower Delaware River Basin, New Jersey, 

2002–07.
Relations of Water Quality to Streamflow, Season, and Land Development 47

base flow than during stormflow (fig. 20). Total nitrogen load 

is about 10 times higher than that in Gravelly Run, again 

divided nearly equally between base flow and runoff. In this 

basin the effects of small amounts of agricultural and urban 

land use are evident in the elevated loads of nitrogen and 

phosphorus in the runoff.

Values for nitrogen and phosphorus loads for Big Timber 

Creek Basin were surprisingly close to those of Lahaway 

Creek Basin. The large amount of urban land use (73.7 percent) does not appear to contribute a greater nutrient load to 

the stream than the small amount of agricultural land use in the 

Lahaway Creek Basin. The small amount of agricultural land 

in the Blacks Creek Basin is present mostly upstream from 

the headwaters; runoff from these areas may not reach the 

sampling site. Though land-use percentages are similar for the 

Cooper River and Blacks Creek Basins, nutrient loads were 

substantially greater for the Cooper River Basin (by a factor 

of about 15). This may be partially due to historical wastedisposal practices; the Cooper River was highly eutrophic with 

many domestic wastewater-treatment facilities along its length 

until the 1970s and 1980s, when they were removed. Also, the 

Cooper River runs through many lakes and impoundments created by building artificial dams. Many of these are a century 

or more old and have been accumulating silt for decades. A 

portion of the silt is released during each storm, and nutrients 

may be resuspended. Much of the nitrogen in Cooper River 

runoff is in the form of organic nitrogen, which can be bound 

to sediment. The abundant ammonia can be released from the 

anoxic bottom sediment, whereas nitrate can be aerobically 

generated from ammonia by in-stream processes. Phosphorus 

loads also were substantially higher in the Cooper River than 

in Blacks Creek and the two agricultural basins, and this is 

consistent with the sediment-resuspension concept. Two major 

golf country clubs are present along the Cooper River, which 

may be an additional source of nutrients from turf fertilization.

The drainage basins of Blacks Creek and Alloway Creek 

are largely agricultural. Neither have substantial percentages of urban land use; however, Blacks Creek Basin has a 

higher percentage of undeveloped land and a lower percentage of agricultural land than Alloway Creek Basin. Cattle 

were observed during several visits to Alloway Creek, and 

cattle were often seen in the creek. Evidence of cattle waste 

products was abundant. No cattle were observed in the Blacks 

Creek Basin, and the agriculture appeared to consist of row 

crops. Nearly all of the nitrogen in Blacks Creek is in the form 

of nitrate plus nitrite, whereas a substantial portion of the 

nitrogen present in Alloway Creek is in the form of organic 

nitrogen and ammonia. This is consistent with the different 

agricultural focuses in the two basins.

Load values show a strong relation with land use. With 

the exception of the Cooper River site, elevated nutrient levels 

can be directly related to recent land-use patterns. As mentioned above, there is strong evidence that the nutrient load 

in the Cooper River is in large part contributed by sedimentstored nutrients that are released during storms.

Table 10. Annual loads of selected water-quality characteristics for three streams in the lower Delaware River Basin, New Jersey.

[Total N, total nitrogen; Organic N, organic nitrogen; NO3+NO2, nitrate plus nitrite; Total P, total phosphorus]

 Station

abbreviation

Station name

(Identifier) 

Annual loads of water-quality characteristic, in pounds per year per square mile

Total N Organic N Ammonia NO3

+NO2 Total P Orthophosphate

UND1 Lahaway Creek 1,931 621 79 1,120 98 33

UND2 Gravelly Run 173 77 26 87 28 10

URB1 Cooper River 10,688 5,668 1,684 3,438 6,043 303

URB2 Big Timber Creek 2,185 700 98 1,444 115 15

AG1 Blacks Creek 4,176 464 51 3,758 186 33

AG2 Alloway Creek 14,730 4,292 1,120 9,634 3,250 70
48 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

Gravelly 

Lahaway 

Big Timber 

Cooper 

Blacks 

Alloway 

0 

2,000 

4,000 

6,000 

8,000 

10,000 

12,000 

STREAM 

YIELD IN POUNDS PER SQUARE MILE PER YEAR 

WATER-QUALITY CHARACTERISTIC 

TP

OP

NO2

NO2+NO3

NH3

Org N

TN

Streams: Alloway, Alloway Creek near Watson’s Corner, NJ; Blacks, Blacks Creek near Chesterfield, NJ; Cooper, Cooper River at Route 561 at Haddonfield, 

NJ; Big Timber, South Branch Big Timber Creek at Grenloch, NJ; Lahaway, Lahaway Creek near Prospertown, NJ; Gravelly, Gravelly Run near Laurel Lake, NJ

Nutrient Species: TP, total phosphorus; OP, orthophosphate; NO2, nitrite; NO2+NO3, nitrite plus nitrate; NH3, ammonia; Org N, organic nitrogen as N; TN, total 

nitrogen

EXPLANATION

Figure 27. Yields of phosphorus and nitrogen nutrient species in six streams in the lower Delaware River Basin, New Jersey, 2002.
References Cited 49

Summary and Conclusions

Water quality and streamflow were monitored during eight storms and during base flow eight times each at 

six streams in the lower Delaware River Basin, New Jersey, 

during 2003–07. Two streams were chosen for each of three 

predominant land uses—agricultural, urban, and undeveloped. 

Blacks Creek (AGR1) and Alloway Creek (AGR2) are predominantly agricultural, Lahaway Creek (UND1) and Gravelly Run (UND2) are mostly undeveloped, and Cooper River 

(URB1) and South Branch Big Timber Creek (URB2) are 

mostly urban. Sampling events were scheduled during growing and nongrowing seasons to observe seasonal effects. Water 

samples for nutrient analysis were collected several times during each storm so that total load and variability of load during 

storms could be determined. Samples were analyzed to determine concentrations of several nitrogen and phosphorus species. The yield (area-normalized load) was calculated for each 

nutrient species for each sample collected. Two-way ANOVA 

of ranked data was used to simultaneously test for differences 

in nutrient-species concentrations and yields among sites, and 

between growing and nongrowing seasons. This was followed 

with the Tukey multiple comparison test.

Nitrate plus nitrite was the most abundant nitrogen constituent at all sites, exceeding 50 percent of the nitrogen mass 

in most samples. Organic nitrogen also was substantial (mean 

value, 32 percent of total nitrogen). When detected, nitrite 

was present at low levels and represented about 1 percent of 

the total nitrogen mass. Ammonia typically represented 3 to 5 

percent.

Concentrations and yields of nitrogen and phosphorus 

species are strongly related to land use with agricultural activities contributing the most nutrient mass to the streams, followed by urban land use. Forests and wetlands contributed the 

least amount of nutrient mass per unit land area. UND2, which 

had essentially no urban development or agriculture, had 

significantly lower nutrient concentrations and yields than any 

other basin. AGR2 had the highest concentrations and yields 

of total nitrogen. Most of this was in the form of nitrate plus 

nitrite; however, a substantial amount of organic nitrogen and 

ammonia were contributed. The AGR2 basin also contributed 

a large amount of phosphorus. Total nitrogen concentration 

and yield values for AGR1 were about one-third of those for 

AGR2, and nearly all of the nitrogen was in the form of nitrate 

plus nitrite. Phosphorus loads were much lower for AGR1 

than for AGR2. The difference in load values between these 

basins is consistent with the difference in the nature of the 

agriculture: livestock were present only in the Alloway Creek 

Basin (AGR2). Annual nitrogen and phosphorus loads at 

URB1, which is largely urban, were high and more similar to 

the agricultural basins than to the other urban basin (URB2). 

A long history of numerous domestic wastewater-treatment 

plants operating along the length of Cooper River, and the 

presence of sediment-laden impoundments, are reasonable 

explanations for this observation. The large organic nitrogen 

and total phosphorus loads are consistent with nutrient release 

from sediment in the Cooper River streambed during storms.

For seasonality, there was no significant difference in 

concentration of any nutrient species between growing and 

nongrowing seasons during base flow. Fecal coliform concentrations were significantly higher in the growing season, probably as a result of warmer temperatures. Yields of all nitrogen species during base flow differed significantly between 

seasons, probably due to hydrologic variability. Concentrations and yields of most nutrient species during stormflow 

were significantly different between growing and nongrowing 

seasons, although box plots revealed that the differences were 

related more to variability than to median values.

References Cited

American Public Health Association, American Water Works 

Association, and Water Environment Federation, 1999, 

Standard methods for the examination of water and wastewater (29th ed.): Washington, D.C., American Public Health 

Association, variously paged.

Anderson, J.R., Hardy, E.E., Roach, J.T., and Witmer, R.E., 

1976. A land use and land cover classification system for 

use with remote sensor data: A revision of the land use classification system as presented in U.S. Geological Survey 

Circular 671: U.S. Geological Survey Professional Paper 

964, 41 p.

Baker, R.J., and Hunchak-Kariouk, K., 2006, Relations of 

water quality to streamflow, season, and land use for four 

tributaries to the Toms River, Ocean County, New Jersey, 

1994–99: U.S. Geological Survey Scientific Investigations 

Report 2005-5274, 72 p.

Bartsch, A.F., 1972, Nutrients and eutrophication—prospects 

and options for the future, in Likens, G.E., ed., Nutrients 

and eutrophication: The limiting nutrient controversy: 

Lawrence, Kansas,The American Society of Limnology and 

Oceanography, 297 p.

Delaware Inland Bays Estuary Program. 1993, Characterization of the inland bays estuary: Dover, DE, Report to the 

Delaware Inland Bays National Estuary Program, 

Delaware Department of Natural Resources and 

Environmental Control.

Delaware River Basin Commission, 1994, Delaware River and 

Bay water quality assessment: 1992–1993: West Trenton, 

New Jersey, Delaware River Basin Commission, 305(b) 

report, 50 p.
50 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

Fischer, J.M., Riva-Murray, Karen, Hickman, R.E., Chichester, 

D.C., Brightbill, R.A., Romanok, K.M., and Bilger, M.D., 

2004, Water quality in the Delaware River Basin, Pennsylvania, New Jersey, New York, and Delaware, 1998–2001: 

U.S. Geological Survey Circular 1227, 38 p. 

Fusillo, T.V., 1981, Impact of suburban residential development on water resources in the area of Winslow Township, 

Camden County, New Jersey: U.S. Geological Survey 

Water-Resources Investigations Report 81–27, 38 p.

Gondar, D., Thacker, S.A., Tipping, E., Baker, A., 2008, 

Functional variability of dissolved organic matter from the 

surface water of a productive lake: Water Research, v. 42, 

no. 1–2, p. 81–90. 

Granéli, E., and Turner, J.T., eds., 2006, Ecology of harmful 

algae: Heidelberg, Germany, Springer, Series: Ecological 

Studies, v. 189, 413 p.

Gray, D.M., 1970, Handbook on the principles of hydrology: 

Huntington, New York, Water Information Center, Inc., 

p. 7.7.

Greeley-Polhemus Group, Inc., 1990, Final report: Delaware 

Estuary Program land use management inventory and 

assessment: West Chester, PA, Greeley-Polhemus Group, 

Inc., 229 p.

Hasse, John E., and Lathrop, Richard, G., 2001, Measuring 

Urban Growth in New Jersey: New Brunswick, Grant F. 

Walton Center for Remote Sensing & Spatial Analysis, 

Rutgers University, NJ. 43 p.

Hasse, J., and Lathrop, R.G., 2008, Tracking New Jersey’s 

dynamic landscape: urban growth and open space loss 

1986–1995–2002. Final report: Glassboro, NJ, Rowan 

University, and New Brunswick, NJ, Rutgers University, 

67 p.

Helsel, D.R., and Hirsch, R.M., 2002, Statistical methods in 

water resources: U.S. Geological Survey Techniques of 

Water-Resources Investigations, book 4, chap. A3, 522 p.

Howarth, R.W., and Marino, R., 2006, Nitrogen as the limiting 

nutrient for eutrophication in coastal marine ecosystems, 

evolving views over three decades: Limnology and Oceanography, v. 51, no. 1, part 2, p. 364–376.

Hunchak-Kariouk, Kathryn, Buxton, D.E., Hickman, 

R.E.,1999, Relations of surface-water quality to streamflow 

in the Atlantic Coastal, Lower Delaware River, and Delaware Bay basins, New Jersey, water years 1976–93: U.S. 

Geological Survey Water-Resources Investigations 

Report 98–4244, 146 p.

Ji, Zhen-Gang, 2008, Modeling rivers, lakes and estuaries: 

Hoboken, NJ, Wiley Interscience, John Wiley & Sons, 

Inc., 676 p.

Jordan, T.J., Weller, D.E., and Correll, D.L., 2003, Sources of 

nutrient inputs to the Patuxent River estuary: Estuaries, v. 

26, no. 2, part A, p. 226–243.

Kennish, M.J., ed., 1997, Practical handbook of estuarine and 

marine pollution: Boca Raton, FL, CRC Press, The CRC 

Marine Science Series, 524 p.

Lathrop, R.G., 2000, New Jersey land cover change analysis 

project, 1972–1984–1995: New Brunswick, N.J., Center for 

Remote Sensing and Spatial Analysis, Cook College, 38 p.

Lehr, J.H., Keeley, J.J., Lehr, J.J., eds., 2005, Water Encyclopedia: Water quality and resource development: Hoboken, 

NJ, Wiley Interscience, John Wiley & Sons, Inc., 717 p.

Linsley, R.K., Kohler, M.A., and Paulhus, J.L.H., 1975, 

Hydrology for engineers: New York, McGraw-Hill, Inc., 

512 p.

 Lynch, J.A, and Corbett, E.S., 1990, Evaluation of best management practices for controlling nonpoint pollution from 

silvicultural operations: Water Resources Bulletin, v. 26, 

no. 1, p. 41–52.

Markley, M.L., 1962, Soil survey of Gloucester County, New 

Jersey: U.S. Soil Conservation Service and New Jersey 

Agricultural Experiment Station, Soil Survey Series 1959 , 

no. 8, 84 p.

Markley, M.L., 1971. Soil survey of Burlington County, New 

Jersey: Washington, D.C., U.S. Department of Agriculture, 

Cartographic Division, Soil Conservation Service, 103 p.

Markley, M.L., 1988, Soil survey of Camden County, New 

Jersey: U.S. Department of Agriculture, Soil Conservation 

Service and New Jersey Agricultural Experiment Station, 

94 p.

Matter, W.J., and Ney, J.J., 1981, The impact of surface mine 

reclamation on headwater streams in southwest Virginia: 

Hydrobiologia, v. 78, p. 63–71.

Metcalf and Eddy, Inc., 1979, Wastewater engineering: Treatment, disposal, reuse: City, Columbus, OH, McGraw Hill, 

920 p.

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

Ruddy, B.C., 1995, Nutrients in ground water and surface 

water of the United States–An analysis of data through 

1992: U.S. Geological Survey Water-Resources Investigations Report 95–4031, 74 p.

Mueller, D.K., and Helsel, D.R., 1999, Nutrients in the 

nation’s waters—too much of a good thing?: U.S. Geological Survey Circular 1136, 24 p.
References Cited 51

National Research Council, 1979, Ammonia, Committee on 

Medical and Biological Effects of Environmental Pollutants, Subcommittee on Ammonia: Baltimore, MD, 

University Park Press, 384 p. 

New Jersey Department of Environmental Protection and 

Energy, 1993, New Jersey 1992 State water quality inventory report: Trenton, N.J., New Jersey Department of Environmental Protection and Energy, 188 p.

New Jersey Department of Environmental Protection, 1998, 

New Jersey 1998 State water quality inventory report: 

Trenton, N.J., New Jersey Department of Environmental 

Protection, sections separately paginated, accessed August 

6, 2001, at http://www.state.nj.us/dep/dsr/watershed/305-

main.htm.

New Jersey Department of Environmental Protection, 2000, 

1995/97 Landuse/Landcover by watershed management 

area (WMA): New Jersey Department of Environmental 

Protection, 2003, N.J.A.C 7, Chapter 9 B, Surface Water 

Quality Standards, 127 p., accessed March 15, 2006, at 

http://www.state.nj.us/dep/dsr/map-integration/LULC95.

htm.

New Jersey Department of Environmental Protection, 2004, 

Amendment to the Tri-County Water Quality Management Plan total maximum daily loads for total phosphorus 

to address four streams segments and two lakes in Cooper 

River watershed, Camden County, Lower Delaware Water 

Region: Trenton, N.J., New Jersey Department of Environmental Protection, 80 p.

New Jersey Department of Environmental Protection, 2008, 

N.J.A.C. 7:9B, Surface Water Quality Standards, Statutory 

Authority: N.J.S.A. 58: 10A-1 et seq., 58:11A-1 et seq., 

and 13:1D-1 et seq., date last amended: June 16, 2008 (40 

N.J.R. 3630(b)): Trenton, N.J., New Jersey Department of 

Environmental Protection. (available on the World Wide 

Web at http://www.state.nj.us/dep/wms/bwqsa/docs/0608_

SWQS.pdf).

New Jersey Department of Environmental Protection, 2009, 

Department approved watershed-based implementation 

plans: Trenton, N.J., New Jersey Department of Environmental Protection, 2 p. (available at http://www.state.nj.us/

dep/watershedmgt/319watershedbased_plan_implementation_projects.htm).

Rantz, S.E., and others, 1982, Measurement and computation 

of streamflow: U.S. Geological Survey Water-Supply Paper 

2175, v. 1, Measurement of stage and discharge, and v. 2, 

Computation of discharge, 631 p.

Rasmussen, T.J., Ziegler, A.C., and Rasmussen, P.P., 2005, 

Estimation of constituent concentrations, densities, loads, 

and yields in Lower Kansas River, northeast Kansas, using 

regression models and continuous water-quality monitoring, January 2000 through December 2003: U.S. Geological 

Survey Scientific Investigations Report 2005–5165, 117 p.

Rasmussen, P.P., and Christensen, V.G., 2005, Hydrologic 

and water-quality conditions in the Kansas River, northeast 

Kansas, November 2001–August 2002, and simulation of 

ammonia assimilative capacity and bacteria transport during 

low flow: U.S. Geological Survey Scientific Investigations 

Report 2005–5188.

Rast, W., and Thornton, J.A., 1996, Trends in eutrophication 

research and control: Hydrological Processes, v. 10, 

p. 295–313.

Redfield, A., 1958, The biological control of chemical factors 

in the environment: American Scientist, v. 46, p. 205–221.

Ruffner, J. A., and Bair, F.E., eds., 1977, The weather almanac: 

Detroit, Michigan, Gale Research Co., 842 p.

Schornick, J.C., Jr., and Fishel, D.K., 1980, Effects of storm 

runoff on water quality in the Mill Creek drainage basin, 

Willingboro, New Jersey: U.S. Geological Survey WaterResources Investigations Report 80-98, 111 p.

Seddon, J.A., 1900, River hydraulics: Transactions of the 

American Society of Civil Engineers, v. 43, p. 179–243.

Senior, L.A., and Koerkle, E.H., 2003, Simulation of streamflow and water quality in the Christina River subbasin and 

overview of simulations in other subbasins of the Christina River Basin, Pennsylvania, Maryland, and Delaware, 

1994–98: U.S. Geological Survey Water-Resources Investigations Report 03–4193,144 p.

Sutton, C.C., O’Herron, J.C., II, Zappalorti, R.T., 1996, The 

scientific characterization of the Delaware Estuary: Forked 

River, N.J: Jackson, NJ, Herpetological Associates, Inc., 

228 p.

U.S. Environmental Protection Agency, 1991, Technical 

support document for water quality-based toxics control: 

Washington, D.C., EPA/505/2-90-001, 335 p.

U.S. Environmental Protection Agency, 2000, Stormwater 

Phase II final rule, small MS4 stormwater program overview: Washington, D.C., EPA 833-F-00-002, 3 p.

U.S. Environmental Protection Agency, 2004, Clean Waters 

Act Section 319: Laws, Regulations, Treaties, 33, USC 

Section 1329, January 24, 2004: Washington, D.C., U.S. 

Environmental Protection Agency, 8 p.
52 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

U.S. Geological Survey, 1986, Land use and land cover digital 

data from 1:250,000- and 1:100,000-scale maps: U.S. 

Geological Survey National Mapping Program Technical 

Instructions: Data users guide 4, 36 p.

Velnich, A., 1982, Drainage Areas in New Jersey: Delaware 

River Basin and streams tributary to Delaware Bay: U.S. 

Geological Survey Open-File Report 82–572, 48 p.

Vitousek, P.M., Jaber, J.D., Howarth, R.W., Likens, G.E., Matson, P.A., Schindler, D.W., Schlesinger, W.H., and Tilman, 

D.G., 1997, Human alteration of the global nitrogen cycle: 

sources and consequences: Ecological Applications, v. 7, 

no. 3, p. 737–750.

Walker, W.J., and Branham, B., 1992, Environmental impacts 

of turfgrass fertilization, in Balogh, J.C., and Walker, W.J., 

eds., Golf course management and construction: Chelsea, 

MI, Environmental issues, p. 105–219.

Walter, D.A., LeBlanc, D.R., Stollenwerk, K.G., and Campo, 

K.W., 1999, Phosphorus transport in sewage-contaminated 

ground water, Massachusetts Military Reservation, Cape 

Cod, Massachusetts, in Morganwalp, D.W., and Buxton, H.T., eds., U.S. Geological Survey Toxic Substances 

Hydrology Program–Proceedings of the Technical Meeting, 

Charleston, South Carolina, March 8–12, 1999–Volume 3 

of 3–Subsurface Contamination from Point Sources: U.S. 

Geological Survey Water-Resources Investigations 

Report 99–4018C, p. 305–315.

Wassmann, P., and Olli, K., eds., 2004, Drainage basin nutrient 

inputs and eutrophication: an integrated approach: Tromsø, 

Norway, University of Tromsø, ISBN 82-91086-36-2, 

325 p.

Watt, M.K., 2000, A hydrologic primer for New Jersey 

watershed management: U.S. Geological Survey WaterResources Investigations Report 2000–4140, 108 p.

Weckström, K., Korhola, A., and Weckström, J., 2007, Impacts 

of eutrophication on diatom life forms and species richness 

in coastal waters of the Baltic Sea, AMBIO: A Journal of 

the Human Environment, v. 36, no. 2, p. 155–160.

Whiley, A.J., 2009, Land use, impervious surface, and water 

quality, City of Redmond: Olympia, Washington, Water 

Quality Program, Washington State Department of Ecology, 

Publication no. 09-10-033, 84 p. (available at http://www.

ecy.wa.gov/biblio/0910033.html).

Wilson, D.C., Burns, S.F., Jarrell, W., Lester, A., and Larson, 

E., 1999, Natural ground-water discharge of orthophosphate 

in the Tualatin Basin, northwest Oregon: Environmental and 

Engineering Geoscience, v. 5, no. 2, p. 189–197. 

Zar, J.H., 1974, Biostatistical analysis: Englewood Cliffs, N.J., 

Prentice-Hall, Inc., 619 p.

Zhao S.C., 2004, Mechanisms of lake eutrophication and technologies for controlling in China: Advance in Earth 

Sciences, v. 19, no. 1, p. 138–140.
Appendix 1. Summary statistics for concentrations and yields of selected 

constituents, by base flow, stormflow, growing season, and nongrowing 

season, in samples from six streams in the lower Delaware River Basin, 

New Jersey, years 2002–07.

[Concentrations are in micrograms per liter except bacteria, which are in most probable number per deciliter; yields are in 

pounds per day per square mile; site locations are given in Fig. 2]

Appendix 1
54 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

Appendix 1. Summary statistics for concentrations and yields of selected constituents, by base flow, stormflow, growing season, 

and nongrowing season, in samples from six streams in the lower Delaware River Basin, New Jersey, years 2002–07.—Continued

[Concentrations are in micrograms per liter except bacteria, which are in most probable number per deciliter; yields are in pounds per day per square mile; site 

locations are given in Fig. 2]

Concentrations of total nitrogen as nitrogen in base flow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 552 613 578 720 7,090 167

1st quartile 673 996 637 848 7,100 175

Mean 727 1,310 717 978 7,610 213

Median 727 1,230 678 897 7,790 181

3rd quartile 792 1,660 736 1,030 7,830 192

Highest value 880 2,080 975 1400 8,230 413

Number of observations 7 6 10 4 5 7

Standard deviation 113 539 129 291 497 88

Yields of total nitrogen as nitrogen in base flow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

1st quartile 2 1.4 2.5 3.5 38 0.3

Mean 2.8 6 3.9 4.7 43 0.43

Median 2.4 3.5 3.5 4.4 38 0.4

3rd quartile 3.5 6.1 5.7 5.7 48 0.61

Highest value 4.6 21 6.2 7.3 56 0.72

Number of observations 7 6 10 4 5 7

Standard deviation 1.1 7.6 1.9 1.9 8.5 0.23

Concentration of total nitrogen as nitrogen in base flow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 689 1,310 591 744 6,910 170

1st quartile 708 1,460 606 794 7,450 187

Mean 789 1,600 621 942 7,660 217

Median 727 1,600 621 857 7,980 195

3rd quartile 840 1,750 637 1,010 8,030 225

Highest value 952 1,890 652 1,310 8,090 307

Number of observations 3 2 2 4 3 4

Standard deviation 142 407 43 253 646 61.2

Yields of total nitrogen as nitrogen in base flow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 4.4 9.4 3 4.2 43 0.6

1st quartile 5.1 9.7 3.4 4.6 48 0.64

Mean 5.7 9.9 3.8 5.3 51 0.73

Median 5.8 9.9 3.8 5.1 54 0.71

3rd quartile 6.3 10 4.2 5.8 54 0.8

Highest value 6.9 10 4.6 6.9 55 0.91

Number of observations 3 2 2 4 3 4

Standard deviation 1.3 0.73 1.1 1.2 6.7 0.14
Appendix 1 55

Appendix 1. Summary statistics for concentrations and yields of selected constituents, by base flow, stormflow, growing season, 

and nongrowing season, in samples from six streams in the lower Delaware River Basin, New Jersey, years 2002–07.—Continued

[Concentrations are in micrograms per liter except bacteria, which are in most probable number per deciliter; yields are in pounds per day per square mile; site 

locations are given in Fig. 2]

Concentration of total nitrogen as nitrogen in stormflow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 582 742 505 556 4,040 173

1st quartile 677 1,080 779 718 5,130 299

Mean 822 1,830 1,230 1,100 6,150 390

Median 719 1,760 988 823 6,290 333

3rd quartile 772 2,010 1,380 1,190 6,960 466

Highest value 1,660 4,150 3,740 3,400 9,,310 927

Number of observations 28 32 30 28 22 21

Standard deviation 274 842 726 667 1340 175

Yield of total nitrogen as nitrogen in stormflow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 2.8 1.2 4.4 6 48 0.47

1st quartile 5.1 12 22 13 59 0.96

Mean 22 49 45 17 120 1.9

Median 7.8 27 32 16 77 1.7

3rd quartile 18 38 72 21 130 2.2

Highest value 150 250 140 30 320 4.7

Number of observations 28 32 30 28 22 21

Standard deviation 35 66 35 6.2 86 1.2

Concentration of nitrogen as nitrogen in stormflow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 571 1,870 514 456 4,800 232

1st quartile 695 1,930 593 594 5,880 294

Mean 885 2,070 1,050 935 6,620 323

Median 966 1,970 911 818 6,500 304

3rd quartile 1,040 2,130 1,470 1,240 7,140 317

Highest value 1,190 2,470 1870 1,640 10,600 716

Number of observations 11 6 12 16 16 18

Standard deviation 216 225 542 396 1,300 101

Yield of total nitrogen as nitrogen in stormflow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 6.2 14 4.9 5.2 58 1

1st quartile 8.7 17 13 10 71 1.5

Mean 15 28 33 22 89 2

Median 11 27 36 12 76 1.9

3rd quartile 17 38 45 31 100 2.2

Highest value 42 45 68 67 140 3.6

Number of observations 11 6 12 16 16 18

Standard deviation 11 13 20 19 27 0.68
56 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

Appendix 1. Summary statistics for concentrations and yields of selected constituents, by base flow, stormflow, growing season, 

and nongrowing season, in samples from six streams in the lower Delaware River Basin, New Jersey, years 2002–07.—Continued

[Concentrations are in micrograms per liter except bacteria, which are in most probable number per deciliter; yields are in pounds per day per square mile; site 

locations are given in Fig. 2]

Concentration of nitrate plus nitrite as N in base flow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 322 401 146 576 6,830 45.1

1st quartile 466 722 219 602 7,090 58.1

Mean 522 1,130 324 816 7,340 105

Median 538 996 350 634 7,320 102

3rd quartile 596 1,480 414 848 7,710 153

Highest value 672 2,090 477 1,420 7,750 166

Number of observations 7 6 10 4 5 7

Standard deviation 118 625 115 403 394 52.1

Yield of nitrate plus nitrite as N in base flow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 0.94 0.33 0.72 1.9 32 0.06

1st quartile 1.4 1 0.97 2.5 36 0.12

Mean 2.1 5.6 1.7 4 42 0.19

Median 1.9 2.9 1.5 3.4 37 0.18

3rd quartile 2.3 5.4 1.9 4.9 49 0.24

Highest value 4.2 21 4.4 7.4 52 0.36

Number of observations 7 6 10 4 5 7

Standard deviation 1.1 7.8 1.1 2.4 8.8 0.1

Concentration of nitrate plus nitrite as nitrogen in base flow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 548 1,050 248 530 5,750 91.3

1st quartile 571 1,180 268 540 6,690 100

Mean 648 1,320 289 738 7,110 102

Median 594 1320 289 655 7,620 103

3rd quartile 698 1,450 309 854 7,780 105

Highest value 801 1,580 330 1,110 7,950 110

Number of observations 3 2 2 4 3 4

Standard deviation 135 375 57.8 271 1,180 7.84

Yield of nitrate plus nitrite as nitrogen in base flow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 3.7 7.5 1.3 3.4 41 0.26

1st quartile 4.3 7.8 1.5 3.5 43 0.33

Mean 4.6 8.1 1.8 4.1 47 0.36

Median 5 8.1 1.8 4.1 46 0.37

3rd quartile 5.1 8.4 2.1 4.6 50 0.4

Highest value 5.2 8.7 2.3 4.6 54 0.42

Number of observations 3 2 2 4 3 4

Standard deviation 0.83 0.86 0.75 0.65 6.6 0.07
Appendix 1 57

Appendix 1. Summary statistics for concentrations and yields of selected constituents, by base flow, stormflow, growing season, 

and nongrowing season, in samples from six streams in the lower Delaware River Basin, New Jersey, years 2002–07.—Continued

[Concentrations are in micrograms per liter except bacteria, which are in most probable number per deciliter; yields are in pounds per day per square mile; site 

locations are given in Fig. 2]

Concentration of nitrate plus nitrite as nitrogen in stormflow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 308 376 110 209 2,000 170

1st quartile 353 643 323 297 2,810 240

Mean 430 925 358 433 4,100 410

Median 415 869 355 422 3,410 300

3rd quartile 486 1,220 409 494 5,430 470

Highest value 605 1,620 570 775 7,450 1,070

Number of observations 28 32 30 28 22 21

Standard deviation 86.6 372 111 156 1,700 260

Yield of nitrate plus nitrite as nitrogen in stormflow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 1.8 0.65 1.5 3.1 27 35

1st quartile 3 6.1 6.4 5 50 53

Mean 9 23 13 7.4 67 95

Median 5.3 13 11 6.7 58 75

3rd quartile 9.2 22 17 8.6 73 130

Highest value 50 120 33 14 150 210

Number of observations 28 32 30 28 22 21

Standard deviation 11 28 8.1 3.5 28 53

Concentration of nitrate plus nitrite as nitrogen in stormflow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 349 1,460 210 217 3,980 63

1st quartile 484 1,500 243 349 5,190 98.2

Mean 580 1,530 423 613 5,770 112

Median 648 1,540 400 561 5,740 108

3rd quartile 681 1,560 618 797 6,600 121

Highest value 753 1,590 659 1,110 7,460 206

Number of observations 11 6 12 15 16 19

Standard deviation 142 47.9 195 303 1,040 33.2

Yield of nitrate plus nitrite as nitrogen in stormflow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 4.7 11 2.1 3.3 51 0.41

1st quartile 6 14 6.3 7.2 62 0.63

Mean 9.4 20 13 11 74 0.67

Median 6.9 20 15 7.8 71 0.66

3rd quartile 11 27 18 13 77 0.72

Highest value 23 29 28 28 120 1

Number of observations 11 6 12 15 15 19

Standard deviation 5.7 7.7 7.5 7.7 19 0.12
58 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

Appendix 1. Summary statistics for concentrations and yields of selected constituents, by base flow, stormflow, growing season, 

and nongrowing season, in samples from six streams in the lower Delaware River Basin, New Jersey, years 2002–07.—Continued

[Concentrations are in micrograms per liter except bacteria, which are in most probable number per deciliter; yields are in pounds per day per square mile; site 

locations are given in Fig. 2]

Concentration of ammonia as nitrogen in base flow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 6.87 7.9 99.7 16.2 36 4.17

1st quartile 22.5 28.6 125 21.4 46.4 7.97

Mean 27.7 47.7 145 34.1 48.3 14.3

Median 23.1 54.9 146 25.3 46.8 11.8

3rd quartile 34.3 65.3 165 38 52.5 20

Highest value 50.5 79.9 180 69.6 59.7 28

Number of observations 7 6 10 4 5 7

Standard deviation 13.7 27.7 25.8 24.1 8.71 8.8

Yield of ammonia as nitrogen in base flow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 0.02 0.01 0.34 0.1 0.17 0

1st quartile 0.07 0.05 0.49 0.11 0.24 0.02

Mean 0.1 0.2 0.76 0.14 0.28 0.03

Median 0.13 0.16 0.65 0.13 0.25 0.03

3rd quartile 0.14 0.22 0.95 0.16 0.32 0.04

Highest value 0.15 0.62 1.4 0.22 0.4 0.06

Number of observations 7 6 10 4 5 7

Standard deviation 0.05 0.23 0.36 0.06 0.09 0.02

Concentration of ammonia as nitrogen in base flow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 28.2 28.2 140 4.17 28.4 9.68

1st quartile 40.1 29.7 144 24.9 34.6 19.8

Mean 52.1 31.3 148 54.7 52.5 51.3

Median 52.1 31.3 148 35.2 40.8 25.7

3rd quartile 64.1 32.9 152 65 64.5 57.2

Highest value 76.1 34.5 157 144 88.2 144

Number of observations 3 2 2 4 3 4

Standard deviation 24 4.47 12.1 61.6 31.5 62.5

Yield of ammonia as nitrogen in base flow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 0.13 0.16 0.8 0.02 0.15 0.03

1st quartile 0.28 0.18 0.85 0.12 0.21 0.05

Mean 0.43 0.2 0.9 0.34 0.38 0.18

Median 0.44 0.2 0.9 0.22 0.28 0.09

3rd quartile 0.58 0.22 0.94 0.43 0.49 0.23

Highest value 0.72 0.25 0.99 0.93 0.7 0.51

Number of observations 3 2 2 4 3 4

Standard deviation 0.3 0.06 0.13 0.4 0.29 0.22
Appendix 1 59

Appendix 1. Summary statistics for concentrations and yields of selected constituents, by base flow, stormflow, growing season, 

and nongrowing season, in samples from six streams in the lower Delaware River Basin, New Jersey, years 2002–07.—Continued

[Concentrations are in micrograms per liter except bacteria, which are in most probable number per deciliter; yields are in pounds per day per square mile; site 

locations are given in Fig. 2]

Concentration of ammonia as nitrogen in stormflow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 4.17 4.17 22.4 4.17 98 4.17

1st quartile 19.5 22.4 91.3 4.46 119 6.02

Mean 25.2 121 126 84.3 201 16.6

Median 23.1 58.9 132 39.6 158 13.7

3rd quartile 24.7 158 168 108 193 23.1

Highest value 73.7 828 276 347 601 68.7

Number of observations 28 32 30 28 22 21

Standard deviation 13.7 164 63.6 103 132 14.4

Yield of ammonia as nitrogen in stormflow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 0.03 0.01 0.49 0.05 0.65 0.01

1st quartile 0.14 0.24 1.9 0.15 1.5 0.03

Mean 0.69 3.8 4.5 1 3.6 0.07

Median 0.23 0.95 3.5 0.8 3.6 0.05

3rd quartile 0.55 2.4 5.3 1.5 5 0.11

Highest value 5.6 29 15 4.3 7.8 0.16

Number of observations 28 32 30 28 22 21

Standard deviation 1.2 7.4 3.9 1.1 2.2 0.05

Concentration of ammonia as nitrogen in stormflow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 28.2 55.3 146 31.7 39.8 9.84

1st quartile 28.3 66.2 190 49.6 127 18

Mean 47.2 171 233 95.8 224 60.5

Median 32.9 114 229 75 223 28.2

3rd quartile 59.8 217 275 127 323 144

Highest value 89.4 439 346 237 429 144

Number of observations 10 6 12 16 16 19

Standard deviation 25 149 59.9 62.8 128 58.9

Yield of ammonia as nitrogen in stormflow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 0.18 0.46 1.4 0.55 0.42 0.06

1st quartile 0.28 0.56 4.1 0.91 1.3 0.16

Mean 1.1 2.8 8.2 2 3.6 0.33

Median 0.36 1.6 7.4 1.5 2.5 0.18

3rd quartile 0.89 3.9 9.6 2.6 5.4 0.7

Highest value 3.8 8 23 4.9 9.3 0.75

Number of observations 10 6 12 16 16 19

Standard deviation 1.4 3 6.2 1.5 3 0.28
60 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

Appendix 1. Summary statistics for concentrations and yields of selected constituents, by base flow, stormflow, growing season, 

and nongrowing season, in samples from six streams in the lower Delaware River Basin, New Jersey, years 2002–07.—Continued

[Concentrations are in micrograms per liter except bacteria, which are in most probable number per deciliter; yields are in pounds per day per square mile; site 

locations are given in Fig. 2]

Concentration of Organic nitrogen as nitrogen in base flow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 33.7 ND 32.6 143 ND 6.33

1st quartile 155 124 66.3 177 213 53.6

Mean 178 151 254 192 251 96.9

Median 181 184 182 211 237 99

3rd quartile 196 225 356 216 437 113

Highest value 328 271 737 222 645 239

Number of observations 7 6 10 3 5 7

Standard deviation 87 124 243 42.7 344 74.5

Yield of Organic nitrogen as nitrogen in base flow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 0.21 0.16 0.07 0.67 1.1 0.01

1st quartile 0.5 0.32 0.37 0.8 1.2 0.11

Mean 0.64 0.41 1.5 0.87 2.1 0.22

Median 0.52 0.34 0.75 0.92 2.1 0.24

3rd quartile 0.69 0.39 2.6 0.97 3 0.32

Highest value 1.4 0.86 4 1 3 0.42

Number of observations 7 5 10 3 4 7

Standard deviation 0.37 0.27 1.6 0.18 1 0.16

Concentration of Organic nitrogen as nitrogen in base flow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 74.9 260 183 70.2 ND ND

1st quartile 95.5 265 187 116 212 37.7

Mean 105 270 192 155 664 64.5

Median 116 270 192 146 437 80.5

3rd quartile 120 275 196 185 1000 107

Highest value 124 280 200 258 1570 181

Number of observations 3 2 2 4 3 4

Standard deviation 26.2 13.7 11.9 78.5 815 110

Yield of Organic nitrogen as nitrogen in base flow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 0.57 1.5 1 0.45 ND ND

1st quartile 0.6 1.6 1.1 0.57 4.9 0.32

Mean 0.77 1.7 1.2 0.98 7.4 0.36

Median 0.63 1.7 1.2 0.64 7.4 0.36

3rd quartile 0.87 1.8 1.2 1.1 10 0.41

Highest value 1.1 1.9 1.3 2.2 13 0.45

Number of observations 3 2 2 4 3 4

Standard deviation 0.29 0.23 0.19 0.81 7.2 0.08
Appendix 1 61

Appendix 1. Summary statistics for concentrations and yields of selected constituents, by base flow, stormflow, growing season, 

and nongrowing season, in samples from six streams in the lower Delaware River Basin, New Jersey, years 2002–07.—Continued

[Concentrations are in micrograms per liter except bacteria, which are in most probable number per deciliter; yields are in pounds per day per square mile; site 

locations are given in Fig. 2]

Concentration of Organic nitrogen as nitrogen in stormflow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 147 ND 110 210 ND ND

1st quartile 195 328 334 251 773 153

Mean 367 785 750 581 1,880 280

Median 261 648 520 382 1,590 237

3rd quartile 401 1060 976 713 2,960 378

Highest value 1,020 1,940 2,930 2,490 6,480 794

Number of observations 28 32 30 28 22 21

Standard deviation 250 552 663 518 1,590 183

Yield of Organic nitrogen as nitrogen in stormflow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 0.86 0.5 1.3 2 0.33 0.21

1st quartile 1.4 4.6 10 5.1 11 0.57

Mean 12 23 28 8.8 55 1.5

Median 2.9 11 18 7.6 30 1.2

3rd quartile 9 19 38 11 70 1.9

Highest value 90 140 110 22 210 4

Number of observations 28 31 30 28 20 20

Standard deviation 23 37 27 4.9 62 1.2

Concentration of Organic nitrogen as nitrogen in stormflow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 120 272 72.2 72.2 ND ND

1st quartile 155 311 226 226 307 30.2

Mean 269 366 256 256 670 135

Median 276 374 261 261 530 160

3rd quartile 360 405 300 300 855 193

Highest value 432 472 443 443 3,590 490

Number of observations 10 6 15 15 16 19

Standard deviation 117 74.5 81.9 81.9 878 135

Yield of Organic nitrogen as nitrogen in stormflow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 1.3 1.9 0.61 0.61 1.1 0.07

1st quartile 1.9 3 2.2 2.2 8.2 0.79

Mean 4.4 5.1 8.2 8.2 12 1.2

Median 3.4 5.3 2.8 2.8 9.7 1

3rd quartile 4.9 6.7 9.4 9.4 13 1.5

Highest value 15 8.6 38 38 36 2.6

Number of observations 10 6 15 15 13 16

Standard deviation 4.1 2.6 11 11 8.5 0.77
62 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

Appendix 1. Summary statistics for concentrations and yields of selected constituents, by base flow, stormflow, growing season, 

and nongrowing season, in samples from six streams in the lower Delaware River Basin, New Jersey, years 2002–07.—Continued

[Concentrations are in micrograms per liter except bacteria, which are in most probable number per deciliter; yields are in pounds per day per square mile; site 

locations are given in Fig. 2]

Concentration of orthophosphate as phosphorus in base flow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 7.23 7.2 6.03 7.2 7.2 7.2

1st quartile 7.63 7.74 9.1 7.2 11.1 11.5

Mean 15.1 12 14.4 14.4 17.3 14.6

Median 9.84 11.6 16.1 11.4 18.6 15.4

3rd quartile 17 16.4 17.2 18.6 24.8 15.7

Highest value 39.4 17.3 ND 27.4 25 25.4

Number of observations 7 6 10 4 5 7

Standard deviation 11.6 4.71 5.73 9.56 8.02 5.8

Yield of orthophosphate as phosphorus in base flow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 0.02 0.01 0.02 0.02 0.05 0.01

1st quartile 0.03 0.02 0.04 0.03 0.05 0.02

Mean 0.06 0.04 0.08 0.08 0.1 0.03

Median 0.04 0.02 0.07 0.07 0.1 0.02

3rd quartile 0.06 0.05 0.12 0.12 0.12 0.04

Highest value 0.16 0.14 0.15 0.14 0.17 0.09

Number of observations 7 6 10 4 5 7

Standard deviation 0.05 0.05 0.05 0.06 0.05 0.03

Concentration of orthophosphate as phosphorus in base flow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 7.58 7.54 7.54 4.06 7.54 4.06

1st quartile 11.5 10.9 10 6.67 10.5 6.67

Mean 13.2 14.3 12.5 10.7 13.9 9.51

Median 15.4 14.3 12.5 11.6 13.5 8.91

3rd quartile 16 17.6 14.9 15.6 17.1 11.8

Highest value 16.6 21 17.4 15.6 20.6 16.2

Number of observations 3 2 2 4 3 4

Standard deviation 4.9 9.52 6.96 5.83 6.55 5.11

Yield of orthophosphate as phosphorus in base flow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 0.03 0.04 0.05 0.03 0.04 0.01

1st quartile 0.09 0.07 0.06 0.03 0.07 0.02

Mean 0.11 0.1 0.07 0.07 0.1 0.03

Median 0.14 0.1 0.07 0.05 0.09 0.03

3rd quartile 0.14 0.12 0.08 0.09 0.13 0.04

Highest value 0.15 0.15 0.09 0.13 0.16 0.06

Number of observations 3 2 2 4 3 4

Standard deviation 0.06 0.08 0.03 0.05 0.06 0.02
Appendix 1 63

Appendix 1. Summary statistics for concentrations and yields of selected constituents, by base flow, stormflow, growing season, 

and nongrowing season, in samples from six streams in the lower Delaware River Basin, New Jersey, years 2002–07.—Continued

[Concentrations are in micrograms per liter except bacteria, which are in most probable number per deciliter; yields are in pounds per day per square mile; site 

locations are given in Fig. 2]

Concentration of orthophosphate as phosphorus in stormflow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 7 6.72 6 10.9 17.4 7.2

1st quartile 8.2 8.93 7.2 15 58.7 8.5

Mean 15.5 22 19.8 22 208 12.6

Median 13.1 12.4 16.2 19.3 175 11.8

3rd quartile 18.5 20.3 23 23.5 335 16.8

Highest value 46.4 100 68.3 74.8 559 20.3

Number of observations 28 32 30 28 22 21

Standard deviation 10 23.6 14.4 13.1 166 4.51

Yield of orthophosphate as phosphorus in stormflow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 0 0.02 0 0.14 0.12 0.02

1st quartile 0.12 0.09 0.2 0.21 0.61 0.04

Mean 0.28 1 0.79 0 4.91 0.06

Median 0.19 0.14 0.52 0.29 3.22 0.05

3rd quartile 0.28 0.33 1 0.56 10 0.06

Highest value 1.46 6.41 3.14 0.94 13.48 0.18

Number of observations 28 32 30 28 22 21

Standard deviation 0 1.74 0.77 0.26 4.96 0.03

Concentration of orthophosphate as phosphorus in stormflow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 8 7.54 8 4.06 10.3 4.06

1st quartile 7.58 7.54 7.54 7.54 26.7 7.54

Mean 12.8 15 18.2 19 89.6 11

Median 7.58 7.54 13.4 10.2 52.6 7.54

3rd quartile 16.9 11.3 23 33.2 113 16.9

Highest value 26 45.9 61.1 38.8 331 20.8

Number of observations 11 6 12 16 16 19

Standard deviation 7 15.4 15.5 13.3 92.2 5.99

Yield of orthophosphate as phosphorus in stormflow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value ND 0.05 ND 0.03 0.08 0.02

1st quartile 0.08 0.07 0.17 0.06 0.28 0.05

Mean 0.32 ND 1 1 1.7 0.07

Median 0.09 0.1 0.24 0.11 0.58 0.05

3rd quartile 0.36 0.2 1 1.7 2 0.11

Highest value 1.2 0.84 6.3 4.6 9.7 0.16

Number of observations 11 6 12 16 16 19

Standard deviation 0.29 0.3 1.8 1.5 2.5 0.05
64 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

Appendix 1. Summary statistics for concentrations and yields of selected constituents, by base flow, stormflow, growing season, 

and nongrowing season, in samples from six streams in the lower Delaware River Basin, New Jersey, years 2002–07.—Continued

[Concentrations are in micrograms per liter except bacteria, which are in most probable number per deciliter; yields are in pounds per day per square mile; site 

locations are given in Fig. 2]

Concentration of total phosphorus as phosphorus in base flow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 19.8 27.7 29.3 19.5 39.5 14.4

1st quartile 24.2 36.8 37.4 19.7 47.3 16.6

Mean 35.8 55.8 147 28.7 80.1 24.4

Median 26.2 41.5 76.4 26.3 56.3 19.5

3rd quartile 31.5 77.7 154 35.3 61.5 27.2

Highest value 93.1 99.2 684 42.6 196 49.5

Number of observations 7 6 10 4 5 7

Standard deviation 25.8 30.4 198 11.2 65.3 12.3

Yield of total phosphorus as phosphorus in base flow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 0.07 0.03 0.09 0.06 0.18 0.01

1st quartile 0.08 0.07 0.19 0.08 0.27 0.03

Mean 0.14 0.25 0.83 0.15 0.48 0.06

Median 0.09 0.13 0.29 0.15 0.32 0.03

3rd quartile 0.13 0.15 0.92 0.22 0.33 0.06

Highest value 0.39 0.99 3.6 0.23 1.3 0.18

Number of observations 7 6 10 4 5 7

Standard deviation 0.11 0.37 1.1 0.09 0.47 0.06

Concentration of total phosphorus as phosphorus in base flow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 19.5 38.3 28.8 13.6 29.4 16.2

1st quartile 24.6 40.1 34.8 18 34.8 18.7

Mean 27.2 41.9 40.8 20.3 39.8 41.5

Median 29.6 41.9 40.8 20.4 40.3 19.7

3rd quartile 31.1 43.6 46.9 22.6 45 42.6

Highest value 32.5 45.4 52.9 26.7 49.6 110

Number of observations 3 2 2 4 3 4

Standard deviation 6.83 5 17.1 5.39 10.1 46

Yield of total phosphorus as phosphorus in base flow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 0.09 0.25 0.15 0.08 0.16 0.05

1st quartile 0.17 0.26 0.2 0.09 0.24 0.05

Mean 0.22 0.26 0.26 0.12 0.27 0.15

Median 0.25 0.26 0.26 0.11 0.32 0.07

3rd quartile 0.28 0.27 0.32 0.14 0.33 0.17

Highest value 0.31 0.27 0.37 0.18 0.34 0.39

Number of observations 3 2 2 4 3 4

Standard deviation 0.11 0.02 0.16 0.05 0.1 0.16
Appendix 1 65

Appendix 1. Summary statistics for concentrations and yields of selected constituents, by base flow, stormflow, growing season, 

and nongrowing season, in samples from six streams in the lower Delaware River Basin, New Jersey, years 2002–07.—Continued

[Concentrations are in micrograms per liter except bacteria, which are in most probable number per deciliter; yields are in pounds per day per square mile; site 

locations are given in Fig. 2]

Concentration of total phosphorus as phosphorus in stormflow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 17.2 27.2 49.5 26.6 53.3 8.15

1st quartile 23.7 109 132 41.1 153 18.1

Mean 54.1 532 759 93.4 582 21.2

Median 40.4 262 343 66.8 383 19.5

3rd quartile 68.1 775 974 117 864 23.1

Highest value 210 2,510 4,340 294 2,290 34.8

Number of observations 28 32 30 28 22 20

Standard deviation 43.6 607 990 72.7 545 6.02

Yield of total phosphorus as phosphorus in stormflow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 0.09 0.06 0.42 0.28 0.5 0.03

1st quartile 0.25 1.4 3.9 0.61 1.8 0.06

Mean 1.8 22 31 1.7 15 0.1

Median 0.39 3.4 12 1.3 6.1 0.11

3rd quartile 1.1 18 33 2.1 23 0.13

Highest value 17 220 260 6.2 64 0.22

Number of observations 28 32 30 28 22 20

Standard deviation 4 46 54 1.4 19 0.04

Concentration of total phosphorus as phosphorus in stormflow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 19.5 ND 42.4 19.5 48.6 16.4

1st quartile 23.6 44.5 67.2 31.1 87.4 19.5

Mean 27.9 141 259 39.6 175 36.5

Median 25.7 118 149 39.5 166 19.5

3rd quartile 29.8 189 477 49.7 248 30.5

Highest value 49.2 404 736 58.1 349 110

Number of observations 11 7 12 16 16 18

Standard deviation 8.14 141 237 12.3 98.2 34.4

Yield of total phosphorus as phosphorus in stormflow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 0.16 ND 0.53 0.14 0.48 0.08

1st quartile 0.23 0.34 1.5 0.24 0.9 0.12

Mean 0.58 2.3 8.2 1.7 2.9 0.2

Median 0.3 1.4 6 0.44 1.8 0.14

3rd quartile 0.55 3.3 16 2.5 4.7 0.17

Highest value 2.1 7.4 19 6.7 10 0.57

Number of observations 11 7 12 16 16 18

Standard deviation 0.63 2.7 7.2 2.2 2.7 0.16
66 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

Appendix 1. Summary statistics for concentrations and yields of selected constituents, by base flow, stormflow, growing season, 

and nongrowing season, in samples from six streams in the lower Delaware River Basin, New Jersey, years 2002–07.—Continued

[Concentrations are in micrograms per liter except bacteria, which are in most probable number per deciliter; yields are in pounds per day per square mile; site 

locations are given in Fig. 2]

Concentration of fecal coliform in base flow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 3.00E+0 7.00E+0 1.10E+2 3.00E+0 3.10E+2 1.00E+1

1st quartile 8.50E+0 1.45E+2 1.40E+2 4.58E+1 1.04E+3 1.65E+1

Mean 3.73E+3 2.57E+2 4.55E+3 7.08E+1 2.59E+3 1.94E+2

Median 3.00E+1 1.75E+2 3.64E+2 7.50E+1 2.40E+3 6.30E+1

3rd quartile 1.54E+2 2.88E+2 6.60E+3 1.00E+2 3.42E+3 1.75E+2

Highest value 2.58E+4 7.27E+2 1.70E+4 1.30E+2 5.80E+3 9.00E+2

Number of observations 7 6 10 4 5 7

Standard deviation 9.73E+3 2.51E+2 6.57E+3 5.35E+1 2.16E+3 3.23E+2

Yield of fecal coliform in base flow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 8.53E+7 3.10E+8 1.27E+9 6.96E+7 9.32E+9 7.75E+7

1st quartile 1.21E+8 1.37E+9 3.23E+9 6.55E+8 2.24E+10 1.08E+8

Mean 7.01E+10 1.91E+9 1.16E+11 1.67E+9 6.22E+10 2.37E+9

Median 1.44E+8 2.42E+9 5.84E+9 1.26E+9 6.97E+10 2.05E+8

3rd quartile 2.00E+9 2.59E+9 1.97E+11 2.27E+9 7.22E+10 1.68E+9

Highest value 4.86E+11 2.67E+9 4.12E+11 4.09E+9 1.37E+11 1.27E+10

Number of observations 7 6 10 4 5 7

Standard deviation 1.83E+11 9.86E+8 1.60E+11 1.74E+9 5.04E+10 4.65E+9

Concentration of fecal coliform in base flow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 3.00E+0 3.00E+0 3.00E+1 1.00E+1 5.70E+1 1.00E+1

1st quartile 1.65E+1 7.25E+0 3.43E+1 1.00E+1 4.38E+3 1.00E+1

Mean 4.93E+1 1.15E+1 3.85E+1 4.85E+1 6.25E+3 1.25E+1

Median 3.00E+1 1.15E+1 3.85E+1 4.35E+1 8.70E+3 1.00E+1

3rd quartile 7.25E+1 1.58E+1 4.28E+1 8.20E+1 9.35E+3 1.25E+1

Highest value 1.15E+2 2.00E+1 4.70E+1 9.70E+1 1.00E+4 2.00E+1

Number of observations 3 2 2 4 3 4

Standard deviation 5.84E+1 1.20E+1 1.20E+1 4.52E+1 5.40E+3 5.00E+0

Yield of fecal coliform in base flow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 6.25E+7 7.37E+7 6.85E+8 1.85E+8 1.35E+9 1.10E+8

1st quartile 6.02E+8 2.14E+8 8.84E+8 3.30E+8 1.31E+11 1.41E+8

Mean 2.06E+9 3.55E+8 1.08E+9 1.19E+9 2.06E+11 1.96E+8

Median 1.14E+9 3.55E+8 1.08E+9 1.20E+9 2.62E+11 1.79E+8

3rd quartile 3.05E+9 4.96E+8 1.28E+9 2.06E+9 3.08E+11 2.33E+8

Highest value 4.96E+9 6.37E+8 1.48E+9 2.20E+9 3.54E+11 3.15E+8

Number of observations 3 2 2 4 3 4

Standard deviation 2.58E+9 3.98E+8 5.62E+8 1.06E+9 1.83E+11 8.86E+7
Appendix 1 67

Appendix 1. Summary statistics for concentrations and yields of selected constituents, by base flow, stormflow, growing season, 

and nongrowing season, in samples from six streams in the lower Delaware River Basin, New Jersey, years 2002–07.—Continued

[Concentrations are in micrograms per liter except bacteria, which are in most probable number per deciliter; yields are in pounds per day per square mile; site 

locations are given in Fig. 2]

Concentration of E. coli in base flow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 3.00E+0 3.00E+0 9.00E+1 3.00E+0 1.90E+2 7.00E+0

1st quartile 6.50E+0 6.25E+1 1.63E+2 3.83E+1 9.00E+2 1.50E+1

Mean 4.04E+2 2.05E+2 1.81E+3 5.58E+1 2.05E+3 4.00E+1

Median 2.00E+1 1.69E+2 2.25E+2 5.50E+1 1.95E+3 2.00E+1

3rd quartile 1.95E+2 2.24E+2 1.88E+3 7.25E+1 3.10E+3 4.65E+1

Highest value 2.40E+3 6.20E+2 9.10E+3 1.10E+2 4.10E+3 1.30E+2

Number of observations 7 6 10 4 5 7

Standard deviation 8.90E+2 2.22E+2 3.06E+3 4.39E+1 1.59E+3 4.28E+1

Yield of E. coli in base flow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 4.65E+7 1.33E+8 1.39E+9 6.96E+7 5.71E+9 7.10E+7

1st quartile 1.09E+8 7.79E+8 3.22E+9 5.48E+8 1.94E+10 9.39E+7

Mean 7.25E+9 1.36E+9 4.72E+10 1.17E+9 5.10E+10 3.56E+8

Median 2.87E+8 1.51E+9 3.71E+9 1.30E+9 3.97E+10 1.13E+8

3rd quartile 2.48E+9 2.04E+9 6.34E+10 1.92E+9 9.32E+10 4.61E+8

Highest value 4.52E+10 2.27E+9 2.11E+11 2.03E+9 9.70E+10 1.20E+9

Number of observations 7 6 10 4 5 7

Standard deviation 1.68E+10 8.58E+8 7.64E+10 9.46E+8 4.21E+10 4.35E+8

Concentration of E. coli in base flow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 3.00E+0 3.00E+0 5.00E+1 7.00E+0 5.70E+1 1.00E+1

1st quartile 1.15E+1 9.75E+0 5.25E+1 2.43E+1 3.53E+3 1.53E+1

Mean 7.43E+1 1.65E+1 5.50E+1 4.43E+1 9.02E+3 1.68E+1

Median 2.00E+1 1.65E+1 5.50E+1 3.00E+1 7.00E+3 1.85E+1

3rd quartile 1.10E+2 2.33E+1 5.75E+1 5.00E+1 1.35E+4 2.00E+1

Highest value 2.00E+2 3.00E+1 6.00E+1 1.10E+2 2.00E+4 2.00E+1

Number of observations 3 2 2 4 3 4

Standard deviation 1.09E+2 1.91E+1 7.07E+0 4.52E+1 1.01E+4 4.72E+0

Yield of E. coli in base flow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 6.25E+7 7.37E+7 1.37E+9 1.29E+8 1.35E+9 1.10E+8

1st quartile 4.12E+8 2.94E+8 1.42E+9 6.75E+8 1.06E+11 2.28E+8

Mean 3.15E+9 5.14E+8 1.47E+9 1.10E+9 3.07E+11 2.73E+8

Median 7.61E+8 5.14E+8 1.47E+9 9.96E+8 2.10E+11 2.85E+8

3rd quartile 4.70E+9 7.35E+8 1.52E+9 1.42E+9 4.60E+11 3.30E+8

Highest value 8.63E+9 9.55E+8 1.57E+9 2.28E+9 7.09E+11 4.11E+8

Number of observations 3 2 2 4 3 4

Standard deviation 4.76E+9 6.23E+8 1.44E+8 8.95E+8 3.63E+11 1.25E+8
68 Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07

Appendix 1. Summary statistics for concentrations and yields of selected constituents, by base flow, stormflow, growing season, 

and nongrowing season, in samples from six streams in the lower Delaware River Basin, New Jersey, years 2002–07.—Continued

[Concentrations are in micrograms per liter except bacteria, which are in most probable number per deciliter; yields are in pounds per day per square mile; site 

locations are given in Fig. 2]

Concentration of E. coli in stormflow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 1.00E+1 3.00E+0 1.90E+2 9.30E+1 4.40E+2 3.00E+0

1st quartile 1.23E+2 6.00E+2 1.30E+3 1.23E+3 9.65E+3 1.33E+2

Mean 2.68E+3 6.19E+3 7.80E+3 6.57E+3 7.49E+4 4.02E+3

Median 1.20E+3 2.80E+3 5.50E+3 3.45E+3 1.97E+4 5.25E+2

3rd quartile 3.90E+3 7.80E+3 1.20E+4 7.95E+3 7.83E+4 6.18E+3

Highest value 1.41E+4 4.20E+4 3.40E+4 3.77E+4 8.50E+5 1.98E+4

Number of observations 37 41 37 28 23 22

Standard deviation 3.26E+3 9.04E+3 7.79E+3 8.80E+3 1.73E+5 6.33E+3

Yield of E. coli in stormflow, growing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 2.20E+8 1.30E+8 2.10E+10 4.50E+9 2.10E+10 6.80E+7

1st quartile 9.80E+9 1.30E+10 2.10E+11 7.20E+10 4.90E+11 2.80E+9

Mean 2.60E+11 9.70E+11 1.30E+12 7.10E+11 9.90E+12 5.30E+10

Median 6.20E+10 9.70E+10 5.40E+11 2.20E+11 8.00E+11 1.30E+10

3rd quartile 3.30E+11 7.50E+11 2.20E+12 5.90E+11 8.20E+12 7.80E+10

Highest value 2.70E+12 1.20E+13 4.60E+12 4.20E+12 1.20E+14 3.10E+11

Number of observations 37 41 37 28 23 22

Standard deviation 5.00E+11 2.20E+12 1.30E+12 1.10E+12 2.50E+13 8.40E+10

Concentration of E. coli in stormflow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 3.30E+1 1.70E+1 2.00E+2 7.70E+1 5.60E+2 1.70E+1

1st quartile 6.75E+1 1.00E+2 6.25E+2 1.09E+2 1.37E+4 4.90E+1

Mean 7.57E+2 1.72E+2 4.63E+3 1.96E+3 6.22E+4 8.47E+2

Median 2.00E+2 1.50E+2 9.00E+2 3.00E+2 1.44E+4 6.05E+2

3rd quartile 3.50E+2 2.75E+2 1.03E+4 3.15E+3 1.00E+5 1.51E+3

Highest value 4.70E+3 3.00E+2 1.44E+4 7.20E+3 2.20E+5 2.17E+3

Number of observations 15 10 12 15 17 20

Standard deviation 1.55E+3 1.03E+2 5.95E+3 2.65E+3 7.75E+4 7.86E+2

Yield of E. coli in stormflow, nongrowing season

Site UND1 AGR1 URB1 URB2 AGR2 UND2

Lowest value 9.60E+8 6.30E+8 1.50E+10 3.10E+9 1.90E+10 4.70E+8

1st quartile 3.10E+9 4.00E+9 4.80E+10 3.80E+9 5.90E+11 1.30E+9

Mean 1.60E+11 1.20E+10 1.30E+12 6.70E+11 5.40E+12 2.60E+10

Median 9.30E+9 1.10E+10 8.10E+10 1.30E+10 1.00E+12 1.40E+10

3rd quartile 1.60E+10 1.60E+10 2.00E+12 9.00E+11 6.60E+12 4.40E+10

Highest value 1.40E+12 2.50E+10 6.60E+12 3.80E+12 2.60E+13 9.50E+10

Number of observations 15 10 12 15 17 20

Standard deviation 4.0E+11 8.80E+9 2.20E+12 1.20E+12 8.30E+12 2.80E+10
For additional information, write to:

Director

U.S. Geological Survey

New Jersey Water Science Center

Mountain View Office Park

810 Bear Tavern Rd., Suite 206

West Trenton, NJ 08628

or visit our Web site at:

http://nj.usgs.gov/
Baker and Esralew—Relation of Water Quality to Land Use in the Basins of Six Tributaries to the Lower Delaware R., NJ, 2002–07—Scientific Investigations Report 2010–5151