U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2010–5088

Prepared in cooperation with the New Jersey Department of Environmental Protection

Trends in the Quality of Water in New Jersey Streams, 

Water Years 1998–2007

Trends in the Quality of Water in New Jersey 

Streams, Water Years 1998–2007

By R. Edward Hickman and Bonnie J. Gray

Prepared in cooperation with the 

New Jersey Department of Environmental Protection

Scientific Investigations Report 2010–5088

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

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Hickman, R. E., and Gray, B.J., 2010, Trends in the quality of water in New Jersey streams, water years 1998–2007: 

U.S. Geological Survey Scientific Investigations Report 2010–5088, 70 p.
iii

Contents

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

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

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

Description of Study Area ...................................................................................................................2

Previous Studies ...................................................................................................................................2

Study Methods and Design..........................................................................................................................4

Field and Laboratory Measurements ................................................................................................4

Stations Included in this Study..................................................................................................4

Field and Laboratory Methods...................................................................................................4

Development of Data Sets to be Analyzed .......................................................................................9

Recensoring of some Nondetect Values .................................................................................9

Calculation of Total Organic Nitrogen plus Ammonia..........................................................10

Selection of One Measurement in each Season of each Water Year..............................10

Calculation of Summary Statistics...................................................................................................10

Identification of Trends in Water Quality ........................................................................................11

Seasonal Kendall Test...............................................................................................................11

Tobit Regression.........................................................................................................................12

Comparison of Trends from this Study with Trends from Previous Studies..............................13

Comparison of pH Values before and after a Change in Field Methods....................................13

Trends in the Quality of Water in New Jersey Streams ........................................................................14

Trends determined from the Seasonal Kendall Test .....................................................................14

Dissolved Oxygen.......................................................................................................................14

pH........ .........................................................................................................................................21

Total Dissolved Solids ...............................................................................................................21

Trends Determined from Tobit Regression .....................................................................................26

Total Phosphorus .......................................................................................................................26

Total Organic Nitrogen plus Ammonia ...................................................................................28

Dissolved Nitrate plus Nitrite...................................................................................................28

Summary of Trends by Station..........................................................................................................28

Summary and Conclusions.........................................................................................................................40

References Cited..........................................................................................................................................40

...
iv

Figures

1–2. Map showing—

1. Land use and the Fall Line in New Jersey.......................................................................3

2. Locations of water-quality stations and New Jersey Department of 

Environmental Protection water regions in New Jersey..............................................5

3. Plots showing results of the Seasonal Kendall trend test for concentrations of 

total dissolved solids at the water-quality station on the Whippany River near Pine 

Brook, N.J. (01381900), water years 1998–2007, (A) concentrations as a function of 

streamflow, (B) flow-adjusted concentrations and trend slope as a function of date, 

and (C) concentrations and trend slope as a function of date. ..........................................15

4. Maps showing trends in (A) year-round concentrations of dissolved oxygen 

and (B) growing-season concentrations of dissolved oxygen at water-quality 

stations on streams in New Jersey, water years 1998–2007...............................................16

5–6. Plot showing—

5. Values of pH and dissolved oxygen measured continually at the waterquality station on the Delaware River at Trenton, N.J. (01463500), 

September 5–7, 2005 .........................................................................................................18

6. Growing-season concentrations of dissolved oxygen and times of 

measurement as a function of date at the water-quality station on Flat 

Brook near Flatbrookville, N.J. (01440000), water years 1998–2007..........................19

7. Bar chart showing fraction of water-quality stations on streams in New Jersey 

with trends in year-round flow-adjusted concentrations of dissolved oxygen during 

water years 1980–86, 1986–95, and 1998–2007 ......................................................................19

8. Map showing trends in pH at water-quality stations on streams in New Jersey, 

water years 1998–2007...............................................................................................................22

9. Bar chart showing fraction of water-quality stations on streams in New Jersey 

with trends in flow-adjusted values of pH during water years 1980–86, 1986–95, 

and 1998–2007 .............................................................................................................................23

10. Map showing trends in concentrations of total dissolved solids at water-quality 

stations on streams in New Jersey, water years 1998–2007...............................................24

11. Bar chart showing fraction of water-quality stations with trends in flow-adjusted 

concentrations of dissolved solids during water years 1980–86, 1986–95, 

and 1998–2007 .............................................................................................................................26

12. Plots showing results of trend analysis with Tobit regression for total organic 

nitrogen plus ammonia at the water-quality station on the Pequannock River at the 

Macopin Intake Dam, N.J. (01382500), water years 1998–2007, (A) measured 

concentrations as a function of predicted concentrations and (B) measured and 

predicted concentrations and trend slope as a function of date.......................................27

13. Map showing trends in concentrations of total phosphorus at water-quality 

stations on streams in New Jersey, water years 1998–2007...............................................29

14. Bar chart showing fraction of water-quality stations with trends in flow-adjusted 

concentrations of total phosphorus during water years 1986–95 and 1998–2007 ...........30

15. Map showing trends in concentrations of total organic nitrogen plus ammonia at 

water-quality stations on streams in New Jersey, water years 1998–2007......................31

16. Bar chart showing fraction of water-quality stations with trends in flow-adjusted 

concentrations of organic nitrogen compounds during water years 1980–86, 

1986–95, and 1998–2007 .............................................................................................................32
v

Tables

1. Water-quality stations included in this study of trends in the quality of water in 

New Jersey streams, water years 1998–2007 .........................................................................6

2. References for methods of laboratory analyses of selected water-quality 

characteristics measured by the Ambient Surface-Water Quality Monitoring 

Network, New Jersey, water years 1998–2007........................................................................9

3. Water-quality characteristics included in the study of water years 1998–2007 and 

in previous studies of trends of the quality of New Jersey streams. ................................13

4. Summary statistics for dissolved oxygen at water-quality stations on New Jersey 

streams, water years 1998–2007 ..............................................................................................39

5. Results of trend tests on—

5a. Results of trend tests on year-round flow-adjusted concentrations of 

dissolved oxygen at water-quality stations on New Jersey streams, 

water years 1998–2007. ....................................................................................................41

5b. Results of trend tests on growing-season flow-adjusted concentrations of 

dissolved oxygen at water-quality stations on New Jersey streams, 

water years 1998–2007......................................................................................................44

5c. Results of trend tests on flow-adjusted concentrations of year-round and 

growing-season dissolved oxygen at selected water-quality stations on 

New Jersey streams, water years 1998–2007 ..............................................................47

6. Summary statistics for pH at water-quality stations on New Jersey streams, 

water years 1998–2007...............................................................................................................48

7. Results of trend tests on flow-adjusted values of pH at water-quality stations 

on New Jersey streams, water years 1998–2007..................................................................50

8. Summary statistics for total dissolved solids at water-quality stations on New 

Jersey streams, water years 1998–2007.................................................................................53

9. Results of trend tests on flow-adjusted concentrations of total dissolved solids at 

water-quality stations on New Jersey streams, water years 1998–2007..........................55

10. Summary statistics for total phosphorus at water-quality stations on New Jersey 

streams, water years 1998–2007 ..............................................................................................56

11. Results of trend tests on flow-adjusted concentrations of total phosphorus at waterquality stations on New Jersey streams, water years 1998–2007......................................58

12. Summary statistics for total organic nitrogen plus ammonia at water-quality 

stations on New Jersey streams, water years 1998–2007...................................................60

13. Results of trend tests on flow-adjusted concentrations of total organic nitrogen 

plus ammonia at water-quality stations on New Jersey streams, 

water years 1998–2007...............................................................................................................62

14. Summary statistics for dissolved nitrate plus nitrite at water-quality stations 

on New Jersey streams, water years 1998–2007..................................................................64

17. Map showing trends in concentrations of dissolved nitrate plus nitrite at 

water-quality stations on streams in New Jersey, water years 1998–2007......................34

18. Bar chart showing fraction of water-quality stations with trends in flow-adjusted 

concentrations of nitrate compounds during water years 1986–95 and 1998–2007........35
vi

Conversion Factors and Datums

Multiply By To obtain

Area

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

Flow rate

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

Horizontal coordinates of water-quality stations are referenced to North American Datum of 

1927 (NAD 27) or to the North American Datum of 1983 (NAD 83). Maps are referenced to the 

North American Datum of 1983.

Elevation, as used in this report, refers to distance above a vertical datum.

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

15. Results of trend tests on flow-adjusted concentrations of dissolved nitrate plus nitrite 

at water-quality stations on New Jersey streams, water years 1998–2007 .....................66

16. Results of trend tests on flow-adjusted concentrations of dissolved oxygen during 

water years 1998–2007 and earlier periods at selected water-quality stations 

on New Jersey streams.............................................................................................................20

17. Results of trend tests on flow-adjusted values of pH during water years 1998–2007 

and earlier periods at selected water-quality stations on New Jersey streams ............23

18. Results of trend tests on flow-adjusted concentrations of dissolved solids during 

water years 1998–2007 and earlier periods at selected water-quality stations 

on New Jersey streams.............................................................................................................25

19. Results of trend tests on flow-adjusted concentrations of total phosphorus during 

water years 1998–2007 and water years 1986–1995 at selected water-quality 

stations on New Jersey streams .............................................................................................30

20. Results of trend tests on flow-adjusted concentrations of organic nitrogen 

compounds during water years 1998–2007 and earlier periods at selected waterquality stations on New Jersey streams ................................................................................33

21. Results of trend tests on flow-adjusted concentrations of nitrate compounds during 

water years 1998–2007 and water years 1986–1995 at selected water-quality 

stations on New Jersey streams .............................................................................................36

22. Results of trend tests on flow-adjusted values of six water-quality characteristics 

at water-quality stations on New Jersey streams, water years 1998–2007 .....................37
Trends in the Quality of Water in New Jersey Streams, 

Water Years 1998–2007

By R. Edward Hickman and Bonnie J. Gray

Abstract

Trends were determined in flow-adjusted values of 

selected water-quality characteristics measured year-round 

during water years 1998–2007 (October 1, 1997, through 

September 30, 2007) at 70 stations on New Jersey streams. 

Water-quality characteristics included in the analysis are dissolved oxygen, pH, total dissolved solids, total phosphorus, 

total organic nitrogen plus ammonia, and dissolved nitrate plus 

nitrite. In addition, trend tests also were conducted on measurements of dissolved oxygen made only during the growing 

season, April to September. Nearly all the water-quality data 

analyzed were collected by the New Jersey Department of 

Environmental Protection and the U.S. Geological Survey as 

part of the New Jersey Department of Environmental Protection Ambient Surface-Water Quality Monitoring Network.

Monotonic trends in flow-adjusted values of water quality were determined by use of procedures in the ESTREND 

computer program. A 0.05 level of significance was selected 

to indicate a trend. Results of tests were not reported if there 

were an insufficient number of measurements or insufficient 

number of detected concentrations, or if the results of the tests 

were affected by a change in data-collection methods.

Trends in values of dissolved oxygen, pH, and total dissolved solids were identified using the Seasonal Kendall test. 

Trends or no trends in year-round concentrations of dissolved 

oxygen were determined for 66 stations; decreases at 4 stations and increases at 0 stations were identified. Trends or no 

trends in growing-season concentrations of dissolved oxygen 

were determined for 65 stations; decreases at 4 stations and 

increases at 4 stations were identified. Tests of pH values 

determined trends or no trends at 26 stations; decreases at 2 

stations and increases at 3 stations were identified. Trends 

or no trends in total dissolved solids were reported for all 70 

stations; decreases at 0 stations and increases at 24 stations 

were identified.

Trends in total phosphorus, total organic nitrogen plus 

ammonia, and dissolved nitrate plus nitrite were identified by 

use of Tobit regression. Two sets of trend tests were conducted 

—one set with all measurements and a second set with all 

measurements except the most extreme outlier if one could 

be identified. The result of the test with all measurements 

is reported if the results of the two tests are equivalent. The 

result of the test without the outlier is reported if the results of 

the two tests are not equivalent.

Trends or no trends in total phosphorus were determined 

for 69 stations. Decreases at 12 stations and increases at 5 stations were identified. Of the five stations on the Delaware 

River included in this study, decreases in concentration were 

identified at four.

Trends or no trends in total organic nitrogen plus ammonia were determined for 69 stations. Decreases and increases 

in concentrations were identified at six and nine stations, 

respectively.

Trends or no trends in dissolved nitrate plus nitrite were 

determined for 66 stations. Decreases and increases in concentration were identified at 4 and 19 stations, respectively.

Introduction

The Ambient Surface Water-Quality Monitoring Network 

(ASWQMN) program has been operated by the New Jersey 

Department of Environmental Protection (NJDEP) in cooperation with the U.S. Geological Survey (USGS) since 1985. 

Under this program, water-quality samples have been collected from streams at stations throughout the State and analyzed for water-quality characteristics. Of particular interest 

to the NJDEP is the quality of streams that either drain areas 

of targeted land-use types or are located in the downstream 

portions of each NJDEP water region. A total of 119 stations 

on nontidal streams are sampled as part of the ASWQMN; as 

many as 115 are sampled in any given water year (October 

1 to September 30, numbered for the year in which it ends). 

Sampled stations include 4 on the Delaware River main stem, 

7 background stations located in areas largely unaffected by 

human activity, and 23 watershed integrator stations with 

relatively large drainage basins that contain multiple land uses. 

There are also 43 land-use-indicator stations; the drainage 

basin of each is composed mostly of a single type of land use. 
2 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Fifteen of these stations are designated as undeveloped, 9 as 

agricultural, 13 as urban, and 6 as mixed land uses. In addition, 42 statewide-status stations are chosen randomly every 

2 years. 

Each ASWGMN station is sampled four times a water 

year, once in each of the following periods: November to 

December, February to March, May to June, and August to 

September. Physical characteristics and concentrations of 

filtered and unfiltered nutrients, filtered organic carbon, and 

total dissolved solids are determined on samples of the water 

column. Unfiltered water samples are analyzed for recoverable 

trace elements at selected sites during February to March and 

August to September. Filtered samples of the water column 

collected during May and June are analyzed for pesticides, and 

bed-sediment samples collected during low-flow conditions 

during August and September are analyzed for nutrients and 

trace elements at these selected sites. These data were published annually for water years 1998 to 2005 in USGS reports 

titled “Water Resources Data-New Jersey.” The data for the 

2006 and 2007 water years are now available on the World 

Wide Web and can be accessed at http://wdr.water.usgs.gov/.

The USGS, in cooperation with the NJDEP, conducted a 

study to determine whether there have been monotonic trends 

in the water quality of the streams of New Jersey. The period 

of study is water years 1998–2007 (October 1, 1997 through 

September 30, 2007). A monotonic trend is an underlying 

change in one direction (either an increase or a decrease) in the 

value of a variable over the period of study; this change may 

occur during a short time or throughout the period of study.

Water-quality data for 70 stations were analyzed. 

The data analyzed were collected almost entirely by the 

ASWQMN. The following water-quality characteristics were 

selected for trend analysis by the NJDEP, in cooperation 

with the USGS: dissolved oxygen, pH, total dissolved solids, 

total phosphorus, total organic nitrogen plus ammonia, and 

dissolved nitrate plus nitrite. Year-round measurements of 

each characteristic and those of dissolved oxygen made only 

during the growing season, April to September, were analyzed 

for trends.

The approach was to use procedures in the ESTREND 

computer program (Schertz and others, 1991) to identify 

monotonic trends in flow-adjusted values of each waterquality characteristic at each station. Flow-adjusted values are 

values of water quality which have been modified to remove 

some of the variation in water quality due to the variation in 

streamflow. 

Purpose and Scope

This report presents the results of an analysis to identify 

monotonic trends in selected water-quality characteristics at 

stations on New Jersey streams at which a sufficient number of 

measurements of water quality were made during water years 

1998–2007. Summary statistics of the values of each waterquality characteristic at each station, and results of trend tests 

in flow-adjusted values, are presented in figures and tables. 

Results of trend tests are compared to results from previous 

studies of trends in the quality of New Jersey streams. Results 

are not reported if they were affected by changes in the methods of collection.

Description of Study Area

New Jersey is geologically divided into northern and 

southern regions by the Fall Line (fig. 1) which is marked by 

a series of waterfalls along river courses (Watt, 2000). The 

land to the north of the Fall Line is underlain by sedimentary 

and crystalline bedrock, is higher in elevation, and varies more 

in elevation than land to the south. The land to the south is 

underlain by gravel, sand, silt, and clay.

Land use varies considerably throughout New Jersey 

(fig. 1). Much of the urban land lies close to the Fall Line, 

around New York City in the northeastern part of the State, 

and along the Atlantic Coast. Agricultural land tends to be 

present in the western half of the State, and forest is concentrated in the northwest and southeast.

Previous Studies

Two previous studies reported on trends in the water 

quality measured for the ASWQMN in streams throughout 

New Jersey. Both studies used the procedures in ESTREND 

(Schertz and others, 1991) to identify trends in water-quality 

values unadjusted for streamflow and in flow-adjusted values 

of water quality.

The first report by Hay and Campbell (1990) identified 

changes in water-quality characteristics during two periods 

of record—water years 1976–86 and water years 1980–86. 

Trends tests were conducted on values of 48 water-quality 

characteristics measured at 86 water-quality stations. Results 

were not reported if more than a few percent of the measurements were nondetects. Trends were identified at a 0.1 level of 

significance.

The second report by Hickman and Barringer (1999) 

identified changes in water-quality characteristics during water 

years 1986–95. Trends tests were conducted on 24 waterquality characteristics measured at 83 water-quality stations. 

Trends were identified at a 0.05 level of significance.

In addition, Sprague and others (2009) reported trends 

in total phosphorus, total nitrogen, and nitrate at 20 stations 

on streams in New Jersey as part of their study of selected 

stations across the United States during the period 1993–2003. 

Trends in flow-adjusted concentrations and in concentrations not adjusted for flow were estimated with a parametric 

multiple-regression analysis by use of the program LOADEST 

(Runkel and others, 2004). 
Introduction 3

Figure 1. Land use and the Fall Line in New Jersey.

Trenton

Atlantic City

Philadelphia

New York City

PENNSYLVANIA

DELAWARE

NEW YORK

CONNECTICUT

ATLANTIC OCEAN

75° 74°

41°

40°

39°

0 10 20 MILES

0 10 20 KILOMETERS

Base from U.S. Geological Survey digital line graph files, 1:24,000, 

Universal Transverse Mercator projection, Zone 18, NAD83

2002 digital infrared 

aerial photography 

DELAWARE 

BAY

RARITAN

BAY

EXPLANATION

2002 Land useAgriculture

Barren land

Forest

Urban

Water

Wetlands

Fall Line

MARYLAND

Land-use data from New Jersey Department of

 Environmental Protection, 2007

Delaware River
4 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Study Methods and Design

Water-quality data discussed in this report were 

retrieved from the USGS National Water Information System (NWIS) computer database (described in Mathey, 1998) 

and are available to the public at the USGS NWIS Web site 

(http://waterdata.usgs.gov/nj/nwis/qw/). These data also have 

been published in data reports for water years 1998 to 2005 

(Deluca and others, 1999–2006); reports for water years 

2002 to 2005 can be found (as “pdf” files) at the Web site 

http://pubs.usgs.gov/wdr/#NJ .

Site data sheets containing the water-quality data for each 

station during water years 2006 and 2007 are available at the 

Web site http://wdr.water.usgs.gov/ as “pdf” files. Each site 

data sheet contains the water-quality data for one station for 

one water year.

Field and Laboratory Measurements

Field measurements and sample collection at each station were conducted by personnel of either the USGS or the 

NJDEP. The agency that collected information at each station 

is listed in table 1.

Stations Included in this Study

The 70 water-quality stations included in this study are 

listed in table 1 and shown in figure 2. In this report, the waterquality stations in tables are grouped by the five NJDEP water 

regions (New Jersey Department of Environmental Protection, 

1997, fig. 2), and maps include the water regions so that the 

reader can easily locate the stations. All stations, but one, were 

sampled as part of the ASWQMN and were selected because 

there have been sufficient water-quality measurements for 

trend analysis (see below).

The one station not in the network, the Delaware River 

at Trenton, N.J. (01463500), was included to provide a more 

complete understanding of trends of the main stem Delaware 

River (table 1; fig. 2). This station was sampled by the USGS 

either (1) as part of the USGS National Water-Quality Assessment (NAWQA) Program or (2) in cooperation with the Delaware River Basin Commission. 

These stations (table 1; fig. 2) are characterized by 15 or 

more measurements of water quality, 1 or more measurements 

in the first 2 water years of the period of study, and 1 or more 

measurements in the last 2 water years. Also, there is a value 

of instantaneous streamflow associated with each of these 

water-quality measurements. These characterizations approximate the data requirements necessary for running trend tests in 

ESTREND.

The stations can be divided on the basis of the size of 

the drainage basins. The drainage basins of most stations 

used in the study range from 1.07 to 762 square miles and lie 

entirely within New Jersey or within New Jersey and adjacent 

parts of southern New York (fig. 2; table 1). Five stations 

have drainage basins that range in size from 3,480 to 6,780 

square miles. These stations are on the main stem Delaware 

River, and their basins include large areas of New York and 

Pennsylvania.

Field and Laboratory Methods

Field methods are described in the USGS National Field 

Manual (U.S. Geological Survey, variously dated). At each 

station, a composite sample of streamwater was collected at 

multiple points across the stream using either an open bottle 

or DH-81 sampler when wading, or an open bottle, D-95, or 

DH-95 sampler when sampling from a bridge. This composite 

sample was then split into subsamples using either a churn or 

cone splitter. Subsamples to be analyzed for total dissolved 

solids and dissolved nitrate plus nitrite were filtered. 

The methods used to measure dissolved oxygen concentration at ASWQMN stations differed between the two agencies. The USGS reported the median of measurements at five 

or more points across the stream; measurements were made 

with an YSI model 58 water-quality meter until the beginning 

of water year 2002 and an YSI 600 QS water-quality meter 

during the rest of the period of study. The NJDEP reported the 

concentration at the centroid of streamflow; measurements 

were made with an YSI model 58 throughout the period of 

study. 

The methods used as part of the ASWQMN to measure 

pH during the period of study also differed between the two 

agencies; in addition, the USGS changed its methods during 

the beginning of water year 2002. Through water year 2001, 

the USGS measured pH from a subsample of the composite 

using an Orion PerpHect Ross Combination pH Electrode with 

an epoxy body. Starting at the beginning of water year 2002, 

the USGS reported the median of pH measured at five or more 

points across the stream with a YSI 600 QS meter (during 

water years 2002–07). Throughout the period of study, the 

NJDEP measured pH from a subsample of the composite with 

a Beckman Coulter low-maintenance, gel-filled combination 

electrode. 

Field methods used by the USGS to measure dissolved 

oxygen and pH at the station on the Delaware River at 

Trenton, N.J. (01463500), were different than those used at 

ASWQMN stations. Values of dissolved oxygen and pH were 

measured with an YSI 6820 or YSI 6920 meter at about 12 

points across the river; the reported value of each water-quality characteristic is the median of the measured values. 

Concentrations of total dissolved solids, total phosphorus, 

total organic nitrogen plus ammonia, and dissolved nitrate plus 

nitrite were determined in subsamples sent to USGS laboratories in either Lakewood, Colorado, or Ocala, Florida; methods 

of analysis are listed in table 2. Methods for determining 

concentrations of total phosphorus and total organic nitrogen 

plus ammonia changed during the period of study. For total 

phosphorus, the Kjeldahl sample digestion was replaced with 

a persulfate digestion. Three methods of determination were 

used for total organic nitrogen plus ammonia, the last of which 
Study Methods and Design 5

Delaware River

Maurice River

Great Egg Harbor Riv er

Raritan R i v e r

Passaic River

Delaware River

01482500

01477120

01467359

01467150

01467005

01466500 01465893

01464515

01463850

01464504

01464020

01463500

01461000

01458570

01457500

01457400

01446400

01443500

01443000

01442760

01440000

01438500

01412800

01411955

01411500

01411466

01411444

01411400

01411196

01411110

01411035 01410150

01409500 01409815

01409416

01409387

01408830

01408500

01408100

01408009

01408000

01405340

01403385

01402000

01401400

01400640

01400000

01399780

01398102

01398000

01396660

01395000

01394500

01391500 01389500

01388500

01387500

01382500

01382000

01381800

01380100

01379200

01378780

01378560

01377000

01368820

01367800

01367770

01367625

0140940950

Trenton

Atlantic

City

Philadelphia

New York City

PENNSYLVANIA

DELAWARE

NEW YORK

CONNECTICUT

ATLANTIC OCEAN

75° 74°

41°

40°

39°

0 10 20 MILES

0 10 20 KILOMETERS

Base from U.S. Geological Survey digital line graph files, 1:24,000, 

Universal Transverse Mercator projection, Zone 18, NAD83

DELAWARE 

BAY

RARITAN

BAY

MARYLAND

Areal

reference

100 square

miles

EXPLANATION

New Jersey Department of 

Environmental Protection 

Water Region

Passaic

Raritan

Atlantic Coast

Upper Delaware

Lower Delaware

Location of U.S. Geological Survey

water-quality station and 

identification number. Color denotes 

range of drainage basin area in 

square miles

01412800 10.01–100

01411035 Less than 10

101–1,000

Greater than 1,000

01408500

01463500

Figure 2. Locations of water-quality stations and New Jersey Department of Environmental Protection water regions in 

New Jersey.
6 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007 Table 1. Water-quality stations included in this study of trends in the quality of water in New Jersey streams, water years 1998–2007.—Continued [Stations are grouped by New Jersey Deparment of Environmental Protection water regions; all stations were sampled as part of the NJDEP Ambient Surface Water-Quality Monitoring Network unless oth- erwise indicated; Latitude in degrees minutes seconds; Longitude in degrees minutes seconds; NAD27, North American Datum of 1927; NAD83, North American Datum of 1983; Drainage area is in square miles; NJDEP, New Jersey Department of Environmental Protection; USGS, U.S. Geological Survey] Station number Station name Latitude Longitude Datum for latitude/ longitude Hydrologic unit code Drainage area Collecting agency Streamflow measurements from continuous streamgage at station Passaic Water Region 01377000 Hackensack River at Rivervale, N.J. 405957 0735921 NAD83 02030103 58.00 NJDEP Yes 01378560 Coles Brook at Hackensack, N.J. 405440 0740225 NAD83 02030103 7.00 USGS No 01378780 Primrose Brook at Morristown National Historical Park, N.J. 404554 0743147 NAD83 02030103 1.07 USGS No 01379200 Dead River near Millington, N.J. 403859 0743127 NAD83 02030103 20.80 USGS No 01380100 Beaver Brook at Rockaway, N.J. 405408 0743005 NAD83 02030103 22.20 USGS No 01381800 Whippany River near Pine Brook, N.J. 405042 0742050 NAD83 02030103 68.50 NJDEP Yes 01382000 Passaic River at Two Bridges, N.J. 405350 0741622 NAD83 02030103 361.00 USGS No 01382500 Pequannock River at Macopin Intake Dam, N.J. 410106 0742404 NAD83 02030103 63.70 NJDEP Yes 01387500 Ramapo River near Mahwah, N.J. 410553 0740946 NAD83 02030103 120.00 NJDEP Yes 01388500 Pompton River at Pompton Plains, N.J. 405811 0741655 NAD83 02030103 355.00 NJDEP Yes 01389500 Passaic River at Little Falls, N.J. 405305 0741334 NAD83 02030103 762.00 USGS Yes 01391500 Saddle River at Lodi, N.J. 405325 0740450 NAD83 02030103 54.60 NJDEP Yes Raritan Water Region 01394500 Rahway River near Springfield, N.J. 404115 0741842 NAD83 02030104 25.50 NJDEP Yes 01395000 Rahway River at Rahway, N.J. 403708 0741700 NAD83 02030104 40.90 NJDEP Yes

01396660 Mulhockaway Creek at Van Syckel, N.J. 403851 0745808 NAD83 02030105 11.80 NJDEP Yes01398000 Neshanic River at Reaville, N.J. 402824 0744940 NAD83 02030105 25.70 NJDEP Yes01398102 South Branch Raritan River at South Branch, N.J. 403249 0744147 NAD83 02030105 265.00 USGS No01399780 Lamington River at Burnt Mills, N.J. 403805 0744112 NAD83 02030105 100.00 USGS No01400000 North Branch Raritan River near Raritan, N.J. 403414 0744045 NAD83 02030105 190.00 NJDEP Yes01400640 Millstone River near Grovers Mill, N.J. 401848 0743521 NAD83 02030105 42.60 USGS No01401400 Heathcote Brook at Kingston, N.J. 402210 0743658 NAD83 02030105 9.00 USGS No01402000 Millstone River at Blackwells Mills, N.J. 402830 0743433 NAD83 02030105 258.00 NJDEP Yes01403385 Bound Brook at Route 28 at Middlesex, N.J. 403451 0742957 NAD83 02030105 23.90 USGS No01405340 Manalapan Brook at Federal Road near Manalapan, N.J. 401746 0742352 NAD83 02030105 20.90 USGS No
Study Methods and Design 

7

Table 1. Water-quality stations included in this study of trends in the quality of water in New Jersey streams, water years 1998–2007.—Continued[Stations are grouped by New Jersey Deparment of Environmental Protection water regions; all stations were sampled as part of the NJDEP Ambient Surface Water-Quality Monitoring Network unless otherwise indicated; Latitude in degrees minutes seconds; Longitude in degrees minutes seconds; NAD27, North American Datum of 1927; NAD83, North American Datum of 1983; Drainage area is in square miles; NJDEP, New Jersey Department of Environmental Protection; USGS, U.S. Geological Survey]

Station 

number Station name Latitude Longitude

Datum for 

latitude/

longitude

Hydrologic 

unit code

Drainage 

area

Collecting 

agency

Streamflow 

measurements from 

continuous streamgage 

at station

Atlantic Coastal Water Region

01408000 Manasquan River at Squankum, N.J. 400941 0740917 NAD83 02040301 44.00 NJDEP Yes01408009 Mingamahone Brook near Earle, N.J. 401245 0741006 NAD83 02040301 3.32 USGS No01408100 North Branch Metedeconk River at Lakewood, N.J. 400635 0741309 NAD83 02040301 19.40 USGS No01408500 Toms River near Toms River, N.J. 395911 0741324 NAD83 02040301 123.00 NJDEP Yes01408830 Cedar Creek at Cedar Crest, N.J. 395350 0741859 NAD83 02040301 20.10 USGS No01409387 Mullica River at outlet of Atsion Lk at Atsion, N.J. 394425 0744336 NAD83 02040301 26.70 USGS No

0140940950 Blue Anchor Brook at Elm, N.J. 394117 0745005 NAD83 02040301 4.86 USGS No

01409416 Hammonton Creek at Wescoatville, N.J. 393802 0744304 NAD83 02040301 9.57 USGS No01409500 Batsto River at Batsto, N.J. 393830 0743901 NAD83 02040301 67.80 USGS Yes01409815 West Branch Wading River at Maxwell, N.J. 394030 0743227 NAD83 02040301 85.90 USGS No01410150 East Branch Bass River near New Gretna, N.J. 393723 0742629 NAD83 02040301 8.11 NJDEP Yes

01411035 Hospitality Branch at Blue Bell Road near Cecil, N.J. 393840 0745909 NAD83 02040302 4.51 USGS No

01411110 Great Egg Harbor River at Weymouth, N.J. 393050 0744647 NAD83 02040302 154.00 USGS No

01411196 Babcock Creek near Mays Landing, N.J. 392808 0744133 NAD83 02040302 16.30 USGS No

01411400 Fishing Creek at Rio Grande, N.J. 390139 0745347 NAD83 02040206 2.29 USGS No01411444 West Creek near Leesburg, N.J. 391536 0745441 NAD83 02040206 6.64 USGS No

Upper Delaware Water Region

01367625 Wallkill River at Sparta, N.J. 410225 0743747 NAD83 02020007 5.88 USGS No01367770 Wallkill River near Sussex, N.J. 411138 0743431 NAD83 02020007 60.80 USGS No01367800 Papakating Creek at Pellettown, N.J. 410946 0744031 NAD83 02020007 15.80 NJDEP part01368820 Double Kill at Wawayanda, N.J. 411113 0742512 NAD83 02020007 6.46 USGS No01438500 Delaware River at Montague, N.J. 411833 0744743 NAD83 02040104 3,480.00 NJDEP Yes01440000 Flat Brook near Flatbrookville, N.J. 410622 0745709 NAD83 02040104 64.00 NJDEP Yes01442760 Dunnfield Creek at Dunnfield, N.J. 405814 0750734 NAD83 02040104 3.56 USGS No01443000 Delaware River at Portland, Pa. 405526 0750546 NAD27 02040105 4,165.00 USGS No01443500 Paulins Kill at Blairstown, N.J. 405851 0745712 NAD83 02040105 126.00 NJDEP Yes01446400 Pequest River at Belvidere, N.J. 404945 0750443 NAD83 02040105 157.00 USGS No
8 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007 Table 1. Water-quality stations included in this study of trends in the quality of water in New Jersey streams, water years 1998–2007.—Continued [Stations are grouped by New Jersey Deparment of Environmental Protection water regions; all stations were sampled as part of the NJDEP Ambient Surface Water-Quality Monitoring Network unless oth- erwise indicated; Latitude in degrees minutes seconds; Longitude in degrees minutes seconds; NAD27, North American Datum of 1927; NAD83, North American Datum of 1983; Drainage area is in square miles; NJDEP, New Jersey Department of Environmental Protection; USGS, U.S. Geological Survey] Station number Station name Latitude Longitude Datum for latitude/ longitude Hydrologic unit code Drainage area Collecting agency Streamflow measurements from continuous streamgage at station Upper Delaware Water Region 01457400 Musconetcong River at Riegelsville, N.J. 403533 0751110 NAD83 02040105 156.00 USGS No 01457500 Delaware River at Riegelsville, N.J. 403541 0751123 NAD83 02040105 6,328.00 NJDEP No 01458570 Nishisakawick Creek near Frenchtown, N.J. 403239 0750247 NAD83 02040105 10.10 USGS No 01461000 Delaware River at Lumberville, Pa. 402427 0750216 NAD27 02040105 6,598.00 NJDEP No 01463500 Delaware River at Trenton, N.J. (not part of the NJDEP Ambient Surface Water-Quality Monitoring Network) 401318 0744641 NAD83 02040105 6,780.00 USGS Yes 01463850 Miry Run at Route 533 at Mercerville, N.J. 401449 0744112 NAD83 02040105 10.70 USGS No 01464020 Assunpink Creek at Peace Street at Trenton, N.J. 401302 0744607 NAD83 02040105 91.40 USGS Yes Lower Delaware Water Region 01411466 Indian Branch near Malaga, N.J. 393527 0750335 NAD83 02040206 6.50 USGS No 01411500 Maurice River at Norma, N.J. 392944 0750437 NAD83 02040206 112.00 NJDEP Yes 01411955 Gravelly Run at Laurel Lake, N.J. 392014 0750303 NAD83 02040206 3.19 USGS No 01412800 Cohansey River at Seeley, N.J. 392821 0751520 NAD83 02040206 28.00 USGS Yes 01464504 Crosswicks Creek at Groveville Road at Groveville, N.J. 401002 0744039 NAD83 02040201 98.00 USGS No 01464515 Doctors Creek at Allentown, N.J. 401037 0743556 NAD83 02040201 17.40 USGS No

01465893 Little Creek at Chairville, N.J. 395353 0744718 NAD83 02040202 6.32 USGS No01466500 McDonalds Branch in Byrne State Forest, N.J. 395306 0743019 NAD83 02040202 2.35 NJDEP Yes01467005 North Branch Rancocas Creek at Iron Works Park at Mount Holly, N.J. 395935 0744653 NAD83 02040202 140.00 USGS No01467150 Cooper River at Haddonfield, N.J. 395411 0750117 NAD83 02040202 17.00 NJDEP Yes01467359 North Branch Big Timber Creek at Glendora, N.J. 395004 0750401 NAD83 02040202 18.80 USGS No01477120 Raccoon Creek near Swedesboro, N.J. 394426 0751533 NAD83 02040202 26.90 NJDEP Yes01482500 Salem River at Woodstown, N.J. 393838 0751949 NAD83 02040206 14.60 NJDEP Yes
Study Methods and Design 9

consisted of calculation from concentrations of dissolved 

organic nitrogen plus ammonia and total particulate nitrogen. 

Each concentration value determined at USGS laboratories consists of a remark code and a numeric value. An 

uncensored value (remark code = “ “) indicates that the concentration was reliably determined to be greater than or equal 

to the laboratory reporting level. An estimated value (remark 

code = “E”) indicates that the analyte was detected but could 

not be reliably quantified by the laboratory. A nondetect value 

(remark code = ”<”) indicates that the concentration was less 

than the reporting level. For a given characteristic, the reporting level sometimes changed during the period of study as a 

result of changes in methods or reporting protocols or because 

of the presence of substances in the sample that interfered with 

the analysis. 

Instantaneous streamflow was measured at the time 

of each water-quality measurement or was estimated using 

methods described in Rantz and others (1982). Some streamflow values were taken from the records of the continuous 

streamgages at some of the stations (table 1). Values of streamflow at the station on the Delaware River at Lumberville, Pa. 

(01461000), were estimated from the record of the streamgage 

at the Delaware River at Trenton, N.J. (01463500). 

Development of Data Sets to be Analyzed

Some of the water-quality values retrieved from the 

NWIS database were modified in order to provide a more 

accurate determination of trends than those that would have 

been calculated from unmodified values. These modifications 

are described below. 

Recensoring of some Nondetect Values

For some nondetect values, the USGS National Water 

Quality Laboratory set laboratory reporting levels to twice the 

long-term method detection limit. This practice was used to 

minimize the probability of having a false positive and is discussed in Oblinger-Childress and others (1999). The authors 

note, however, that this practice also complicates interpretation of the data; results of statistical methods calculated 

with nondetects reported with laboratory reporting levels are 

biased. 

To avoid this bias, laboratory reporting levels for nondetect values were set back to the long-term method detection 

level (half the laboratory reporting level). This was one action 

as suggested in Helsel (2005) to avoid bias. 

Table 2. References for methods of laboratory analyses of selected water-quality characteristics measured by the Ambient SurfaceWater Quality Monitoring Network, New Jersey, water years 1998–2007.

Water-quality 

characteristic Comment Reference for method of laboratory determination

Total dissolved solids For period of study Fishman and Friedman (1989)

Total phosphorus From the beginning of the period of study 

through December 31, 2002

Patton and Truitt (1992)

January 1, 2003, to the end of the period of study Patton and Kryskalla (2003)

Total organic nitrogen plus 

ammonia

From the beginning ot the period of study to 

October 1, 1999

Fishman and Friedman (1989)

October 1, 1999 to about December, 2002 Patton and Truitt (2000)

From about December, 2002, to the end of the 

period of study

Calculated1 from laboratory-reported concentrations of dissolved organic nitrogen plus 

ammonia (Fishman, 1993) and total particulate nitrogen (U.S. Environmental Protection 

Agency, 1997)

Dissolved nitrate plus nitrite For period of study Fishman (1993)

1

 Method of calculation is described in the text.
10 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Calculation of Total Organic Nitrogen plus 

Ammonia

As noted in table 2, some values of total organic nitrogen 

plus ammonia (TKN) were not determined by the laboratory 

but were calculated by summing concentrations of dissolved 

organic nitrogen plus ammonia (DKN) and total particulate 

nitrogen (TPN). The set of rules used for this calculation 

follows.

1. If DKN and TPN were both detected, the value of TKN

was determined by summing the numeric values of DKN

and TPN. The remark code for the TKN value was set to 

“E” if the value of either DKN or TPN was estimated.

2. If either DKN or TPN was not detected and the other was 

detected, then:

(a) The ratio (R) was determined from the following 

equation:

R = 100 * (TPN (TPN + DKN)), (1)

where

R = ratio, in percent;

TPN = numeric value of total particulate 

nitrogen, in mg/L as N; and

DKN = numeric value of dissolved organic 

nitrogen plus ammonia, in mg/L as N.

(b) If DKN was detected, TPN was not detected, and the 

ratio, R, was less than or equal to 10 percent, TKN

was determined as follows: 

(i) numeric value of TKN was set equal to the 

numeric value of DKN, and 

(ii) remark code of TKN was set to the remark code 

for DKN.

(c) If DKN was not detected or the ratio, R, was greater 

than 10 percent, TKN was determined as follows: 

(i) TKN = DKN + TPN, (2)

where

TKN = numeric value of total organic 

nitrogen plus ammonia, in mg/L 

as N;

DKN = numeric value of dissolved 

organic nitrogen plus ammonia, 

in mg/L as N; and

TPN = numeric value of total particulate 

nitrogen, in mg/L as N.

(ii) remark code for TKN was set to “<”.

Selection of One Measurement in each Season 

of each Water Year

For each water-quality characteristic, the number of 

water-quality measurements at each station was limited so 

that the summary statistics and results of trend tests were 

comparable among all stations. Four water-quality measurements were made in a water year at most stations included in 

this study. As a result, the water-quality measurements at each 

station were limited to four in a water year, one measurement 

in each of the seasonal months: October to December, January 

to March, April to June, and July to September. If there was 

more than one measurement of a water-quality characteristic 

at a station in any season in any water year, the measurement 

closest to the middle of the season was selected; the remaining 

measurements were not included in the analysis. For dissolved 

oxygen, a separate data set for the growing season was created 

by selecting one measurement in each of two seasons, April to 

June and July to September, in each water year. 

Calculation of Summary Statistics

Summary statistics for the values of each water-quality 

characteristic at each station were determined from the measurements used for trend analysis (one measurement in each 

of four seasons over 10 water years). Statistics include the 

number of measurements; the number of nondetect measurements; the maximum reporting level for nondetect values; the 

minimum and maximum measured values; and the 25th percentile, median, and 75th percentile values. Summary statistics 

for dissolved oxygen were calculated only from year-round 

measurements. 

The 25th percentile, median, and 75th percentile values 

of a water-quality characteristic at a station were determined 

if nondetect values accounted for less than 80 percent of the 

measured values at a station. One of three methods was used 

to determine these statistics for a water-quality characteristic at a station; that method was selected on the basis of the 

percentage of measurements made up of nondetect values. If 

there were no nondetect values, these statistics were calculated 

by use of the Univariate procedure (SAS Institute, Inc., 1999a) 

which ordered the values from smallest to largest. 

If one or more measurements of a water-quality characteristic at a station were nondetects and if 50 percent or fewer 

of the measurements were nondetects, the Kaplan-Meier 

method (described in Helsel, 2005) was used to determine 

the 25th percentile, median, and 75th percentile values at that 

station. Kaplan-Meier is a standard method for estimating 

summary statistics on “survival” data, which are composed of 

uncensored values and right-censored values (“greater thans”). 

To use this method, the set of water-quality values was 

converted to a survival data set by subtracting all the values 

from a constant equal to twice the largest water-quality value. 
Study Methods and Design 11

Summary statistics were determined on this survival data set 

by use of the Lifetest procedure (SAS Institute, Inc., 1999b). 

The resulting summary statistics were converted back to the 

original water-quality data set by subtracting them from the 

constant. 

If nondetect measurements accounted for greater than 

50 percent and less than 80 percent of the values at a station, 

the Regression on Order Statistics (ROS) method (described 

in Helsel, 2005) was used to determine the 25th percentile, median, and 75th percentile values at that station. This 

method is based on developing a linear relation between the 

logarithms of water-quality values as a function of normal 

quantiles. Calculations were done with a computer program 

obtained from the “Practical Statistics for the Sciences” website accessed July 19, 2005, at http://www.practicalstats.com/.

Identification of Trends in Water Quality

Procedures of the ESTREND program (Schertz and 

others, 1991) used to identify monotonic trends in flowadjusted concentrations of water quality were obtained from 

version 3.2 of the USGS library for S-PLUS (David Lorenz, 

U.S. Geological Survey, written commun., 2008), a commercial statistical software package produced by the Insightful Corporation (accessed at http://www.insightful.com/ on 

August 20, 2008). The features of the USGS library used 

for this study are essentially the same as those in version 

2.1 described in Slack and others (2003) and at the website 

http://water.usgs.gov/software/S-PLUS/ (accessed August 8, 

2008). 

Three types of results are produced by the trend tests—

the trend slope, the level of significance of the trend slope, 

and the summary. The trend slope is the “per year” change 

in the flow-adjusted water-quality values during water years 

1998–2007. Each trend slope is expressed (1) in units of 

the water-quality characteristic and (2) as a percentage of a 

representative value (described below) of the water-quality 

characteristic. In some cases, only the direction of the slope 

is reported as “+” (indicating the value tended to increase 

over time) or “-” (indicating the value tended to decrease 

over time). 

The level of significance of the trend slope indicates the 

probability that the trend slope is actually different from zero. 

A trend is not considered to exist if the level of significance of 

the trend test is greater than 0.05. The value of the summary 

result for each of these tests is “no trend.” 

A trend is considered to exist if the level of significance 

of the trend test is less than or equal to 0.05. If the trend 

slope is negative, the results indicate a monotonic decrease 

in flow-adjusted values of water quality during water years 

1998–2007, and the value of the summary result for each of 

these tests is “Decrease.” If the trend slope is positive, the 

results indicate a monotonic increase in flow-adjusted values 

of water quality during this period, and the value of the summary result is “Increase.” 

Seasonal Kendall Test

The Seasonal Kendall test (described in Schertz and others, 1991) was used to identify trends in flow-adjusted values 

of dissolved oxygen, pH, and total dissolved solids; tests were 

conducted on the year-round values of all three characteristics as well as on dissolved oxygen concentrations measured 

during the growing season. This nonparametric test compares 

flow-adjusted water-quality values measured in each season 

throughout the period of study, and then calculates the trend 

in water quality from the results for all seasons included in 

the test.

For each Seasonal Kendall test, ESTREND set the 

representative value to be the median of water-quality values 

included in the test. These median values were computed with 

the Kaplan-Meier method (previously discussed) and, in some 

cases, may be slightly different than the medians presented in 

the tables of summary statistics, which were calculated separately and, possibly, with a different method. 

The first step in running the Seasonal Kendall test on values of a water-quality characteristic at a station is to determine 

flow-adjusted values of water quality. To do this, a relation 

between untransformed values of water quality and instantaneous streamflow was developed. Flow-adjusted values are the 

differences between measured values and the values from the 

relation between water quality and streamflow. 

Two methods were used to develop the relations between 

water quality and streamflow. Most relations were equations 

determined from linear regression; the form of these equations 

is given below:

C = B0 + B1 * log(Q), (3)

where

log = natural logarithm;

C = value of the water-quality characteristic, in 

water-quality units;

B0 = intercept;

B1 = coefficient for instantaneous streamflow; 

and

Q = instantaneous streamflow, in cubic feet per 

second.

A second method, LOESS smoothing (described in 

Schertz and others, 1991), was used in place of linear regression if the relation from LOESS smoothing appeared (from 

inspection of plots) to represent the overall relation between 

water quality and streamflow better than the relation from 

linear regression.

The results of the trend tests on pH were not reported 

if the results appeared to have been affected by a change 

in the methods of measurement. The apparent change in 

pH values due to the change in methods of measurement is 

discussed below.
12 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Results of trend tests for dissolved oxygen and pH are 

not presented if analyses clearly indicated that the results of 

the trend test were affected by a systematic change in time 

of measurement during the period of study. This effect was 

considered to exist if (1) there was a correlation between the 

values of water quality and the time of measurement and (2) 

there was a trend in the time of measurement. The correlation 

between values of water quality and the time of measurement 

was identified from Kendall’s tau correlation (described in 

Helsel and Hirsch, 1992); the level of significance and the 

direction of each relation (whether water quality increased or 

decreased with increasing time of measurement) were determined. Trends in time of measurement were identified with the 

Seasonal Kendall trend test; however, times of measurement 

were not adjusted for streamflow. The direction of the trend 

slope (increase or decrease) and the level of significance of the 

trend slope also were determined.

Tobit Regression

Tobit regression (described in Helsel and Hirsch, 1992, 

and in Cohn, 1988) was used to identify trends in flowadjusted values of total phosphorus, total organic nitrogen 

plus ammonia, and dissolved nitrate plus nitrite at each station. Tobit regression was used because there were nondetect 

values of each of these water-quality characteristics at some 

stations, and Tobit regression can incorporate the information 

in nondetect values as well as the information in uncensored 

values. Tobit regressions were conducted if there were 15 or 

more uncensored or estimated water-quality measurements at 

a station.

Using Tobit regression, an equation relating values of a 

water-quality characteristic at a station to year, streamflow, 

and season was developed. The form of this equation is given 

below. 

log(C) = B0 + (B1 * Year) + (B2 * log(Q)) (4)

+ (B3 * cos(2π * Year)) 

+ (B4 * sin(2π * Year)),

where

log = natural logarithm;

C = value water-quality characteristic, in waterquality units;

B0 = intercept;

B1 = coefficient for Year;

Year = decimal years from October 1, 1997;

B2 = coefficient for instantaneous streamflow;

Q = instantaneous streamflow, in cubic feet per 

second;

B3 = coefficient for first seasonal term;

cos = cosine;

B4 = coefficient for second seasonal term;

sin = sine.

Trend slopes (in units of water quality per year and percent of mean per year) were calculated from the value of the 

coefficient for “Year” (B1) by use of the equations below (Helsel and Hirsch, 1992). The level of significance of the trend 

slopes is the level of significance of B1. The mean of waterquality values, from which the trend slope in water-quality 

units per year at each station was calculated, was determined 

by use of Regression on Order Statistics.

Trendqw = Cmean * (exp(B1) - 1), (5)

where

Trendqw = trend slope, in water-quality units per year;

Cmean = mean of water-quality characteristic, in 

water-quality units;

exp = exponent; and

B1 = coefficient for Year in equation 4.

Trendpct = 100 * (exp(B1) - 1), (6)

where

Trendpct = trend slope, in percent of mean 

concentration per year;

exp = exponent; and

B1 = coefficient for Year in equation 4.

For each of the three water-quality characteristics, two 

trend tests were conducted on the data from most stations. 

One test was conducted on all measurements; a second test 

was conducted on all measurements, except the most extreme 

outlying point if such a point could be identified from plots 

of influence values as a function of date (David Lorenz, U.S. 

Geological Survey, written commun., 2008).
Study Methods and Design 13

Comparison of Trends from this Study with 

Trends from Previous Studies

Trends from this study were compared to the trends from 

studies conducted for New Jersey streams during water years 

1980–86 (Hay and Campbell, 1990) and water years 1986–95 

(Hickman and Barringer, 1999). For each water-quality 

characteristic, the percentages of the stations included in each 

study and that have a trend are shown in a bar chart. Also, 

the results of trend tests in a water-quality characteristic at 

selected stations are shown in a table with the results from the 

previous studies. Only trends identified by Hay and Campbell at the 0.05 level of significance were considered in this 

comparison. 

These comparisons did not always include the same 

water-quality variables in all three studies. Table 3 lists the 

Table 3. Water-quality characteristics included in the study of water years 1998–2007 and in previous studies of trends of the quality 

of New Jersey streams. 

[All analyses shown are in flow-adjusted values; n.a., trends in corresponding water-quality characteristic were not available]

Water years 1998–2007

Were compared with the results of trend analyses in

Hay and Campbell (1990), water years 

1980–86

Hickman and Barringer (1999), water years 

1986–95

Dissolved oxygen, in milligrams per liter Dissolved oxygen, in milligrams per liter Dissolved oxygen, in milligrams per liter

pH, in standard units pH, in standard units pH, in standard units

Total dissolved solids, in milligrams per 

liter

Sum of dissolved constituents, in milligrams per literTotal dissolved solids, in milligrams per 

liter

Total phosphorus, in milligrams per liter 

as P n.a. Total phosphorus, in milligrams per liter as P

Total organic nitrogen plus ammonia, in 

milligrams per liter as N

Total organic nitrogen, in milligrams per 

liter as N

Total organic nitrogen, in milligrams per 

liter as N

Dissolved nitrate plus nitrite, in milligrams 

per liter as N n.a. Total nitrate, in milligrams per liter as N

water-quality characteristics studied by Hay and Campbell 

(1990) and Hickman and Barringer (1999) that were compared 

with water-quality characteristics from this report. Trends in 

flow-adjusted concentrations of total phosphorus and dissolved 

nitrate plus nitrite were, in general, not determined by Hay and 

Campbell (1990).

Comparison of pH Values before and after a 

Change in Field Methods

A rank-sum test was used to determine whether pH 

values collected at each station prior to October 1, 2001, were, 

as a group, different from the group of measurements made 

at that station following this date. This nonparametric test is 

described in Helsel and Hirsch (1992). Differences were considered to exist at the 0.05 level of significance.
14 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Trends in the Quality of Water in New 

Jersey Streams

Summary statistics and results of trend tests are listed 

in tables at the end of this report. Information on dissolved 

oxygen is given in tables 4 (summary statistics), 5a (trend test 

results for year-round measurements), 5b (trend test results 

for growing-season measurements), and 5c (selected trend test 

results for year-round and growing-season measurements). 

Information on pH is given in tables 6 (summary statistics) 

and 7 (trend test results), on total dissolved solids in tables 8 

(summary statistics) and 9 (trend test results), on total phosphorus in tables 10 (summary statistics) and 11 (trend test 

results), on total organic nitrogen plus ammonia in tables 12 

(summary statistics) and 13 (trend test results), and on dissolved nitrate plus nitrite in tables 14 (summary statistics) 

and 15 (trend test results). (Tables 4–15 are at the end of the 

report.)

Summary statistics are presented for measurements of a 

water-quality characteristic at a station even if the measurements were deemed not suitable to test for a trend because the 

reader may find the statistics useful. Each table of summary 

statistics contains an indication of whether trend results are 

presented for a station. Reasons why results of trend tests are 

not presented are discussed below.

Only a small change in level of significance determined 

whether or not a trend was identified. For example, a level of 

significance of 0.051 indicates no trend, but a level of significance of 0.050 indicates a trend. For their own purposes and 

with caution, readers may consider a trend to be indicated by a 

different level of significance.

Trends Determined from the Seasonal Kendall 

Test

Trends in dissolved oxygen, pH, and total dissolved 

solids were identified from the Seasonal Kendall test. As an 

example, the application of the Seasonal Kendall trend test to 

total dissolved solids at the water-quality station on the Whippany River near Pine Brook, N.J. (01381800), is shown in 

figures 3A, 3B, and 3C. Measured concentrations of total dissolved solids as a function of streamflow are shown in figure 

3A, along with concentrations predicted from a least-squares 

regression equation (shown in the figure) relating these concentrations to streamflow. Flow-adjusted concentrations were 

determined by subtracting (1) concentrations predicted from 

the equation from (2) measured concentrations; these flowadjusted concentrations are shown in figure 3B as a function 

of date.

The result of the Seasonal Kendall test indicates that 

flow-adjusted concentrations at the water-quality station on the 

Whippany River near Pine Brook, N.J. (01381800), increased 

during the period of study (table 9). The level of significance 

of the trend slope (0.014) is less than 0.05 and indicates that 

there was a trend in the flow-adjusted concentrations. The 

trend slope, 9.6 milligrams per liter per year, is magnitude of 

this trend (fig. 3B). The trend slope and concentrations are 

shown as a function of date in figure 3C.

Dissolved Oxygen

Results of trend tests of year-round flow-adjusted measurements of dissolved oxygen are presented for 66 stations 

(table 5a; fig. 4A). Decreases in concentrations over the period 

of study were identified at four stations; the slopes of these 

trends range from -0.13 to -0.255 milligrams per liter per 

year (-1.3 to -3.2 percent of median concentrations per year). 

Increases in concentrations over the period of study were not 

identified at any station. Summary statistics for year-round 

measurements of dissolved oxygen are listed in table 4. 

Results of trend tests of growing-season flow-adjusted 

measurements of dissolved oxygen are presented for 65 stations (table 5b; fig. 4B). Decreases in concentrations over the 

period of study were identified at four stations; the slopes of 

these trends range from -0.100 to -0.354 milligrams per liter 

per year (-1.3 to -5.8 percent of medians per year). Increases 

in concentrations over the period of study were identified at 

four stations; the slopes of these trends range from 0.085 to 

0.13 milligrams per liter per year (1 to 1.6 percent of median 

concentrations per year). 

More trends in dissolved oxygen were identified from 

growing-season measurements (8 stations) than from yearround measurements (4 stations) (table 5c). This was expected 

because growing-season measurements are more likely than 

year-round measurements to show the effects of biological and 

chemical processes removing or adding oxygen to a stream. 

During the growing season, water temperatures are usually 

greater than, and the rates of streamflow are usually less than, 

the corresponding values during the nongrowing season (October–March). As a result, dissolved oxygen concentrations 

during the growing season are more likely to differ in saturation than are concentrations during the nongrowing season 

and, by extension, year-round concentrations. The station on 

the Delaware River at Riegelsville, N.J. (01457500), was the 

only station for which trends were identified for both yearround and growing-season measurements; both trends indicate 

decreasing concentrations over the period of study.

Results of trend tests of year-round measurements of dissolved oxygen at four stations and in growing-season measurements at five stations were not presented because these results 

were clearly affected by a trend in time of measurement of 

dissolved oxygen (tables 5a and 5b, respectively). The results 

of those tests for trends in dissolved oxygen were set to “n.d.” 

because (1) there was a trend in times of measurement and (2) 

dissolved oxygen correlated with the time of measurement.
Trends in the Quality of Water in New Jersey Streams 15

Figure 3. Results of the 

Seasonal Kendall trend 

test for concentrations of 

total dissolved solids at the 

water-quality station on 

the Whippany River near 

Pine Brook, N.J. (01381900), 

water years 1998–2007, (A) 

concentrations as a function of 

streamflow, (B) flow-adjusted 

concentrations and trend slope 

as a function of date, and (C) 

concentrations and trend slope 

10/1/1997 10/1/1999 9/30/2001 10/1/2003 9/30/2005 10/1/2007 as a function of date. 

0

200

400

600

800

1,000

C

Measured uncensored concentration

EXPLANATION

Trend slope for flow-adjusted concentrations

Concentration of total dissolved solids,

in milligrams per liter 

Flow-adjusted concentrations increased at 9.6 milligrams per liter per year 

at a 0.014 level of significance 

Flow-adjusted concentrations increased at 9.6 milligrams per liter per year

with a 0.014 level of significance 

10/1/1997 10/1/1999 9/30/2001 10/1/2003 9/30/2005 10/1/2007

-200

0

200

400

600

Flow-adjusted concentration of total

dissolved solids, in milligrams per liter

Trend slope for flow-adjusted concentrations 

Flow-adjusted concentration (measured concentration 

minus predicted concentration)

EXPLANATION B

Total dissolved solids = 542 - 47.7*log(Instantaneous flow)

10 20 30 40 50 60 80 100 200 300 400 600 1,000

Instantaneous streamflow, in cubic fet per second

0

200

400

600

800

1,000

Concentrations of total dissolved solids, 

in milligrams per liter 

Measured uncensored concentration

EXPLANATION

Concentration predicted with equation

A
16 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Delaware River

Maurice River

Great Egg Harbor Riv er

Raritan R i v e r

Passaic River

Delaware River

0140940950

01367625

01367770

01367800

01368820

01377000

01378560

01378780

01379200

01380100

01381800

01382000

01382500

01387500

01388500

01389500 01391500

01394500

01395000

01396660

01398000

01398102

01399780

01400000

01400640

01401400

01402000

01403385

01405340

01408000

01408009

01408100

01408500

01408830

01409387

01409416

01409500 01409815

01410150

01411035

01411110

01411196

01411400

01411444

01411466

01411500

01411955

01412800

01438500

01440000

01442760

01443000

01443500

01446400

01457400

01457500

01458570

01461000

01463500

01464020

01464504

01464515

01465893

01466500

01467005

01467150

01467359

01477120

01482500

01463850

Trenton

Atlantic

City

Philadelphia

New York City

PENNSYLVANIA

DELAWARE

NEW YORK

CONNECTICUT

ATLANTIC OCEAN

75° 74°

41°

40°

39°

0 10 20 MILES

0 10 20 KILOMETERS

Base from U.S. Geological Survey digital line graph files, 1:24,000, 

Universal Transverse Mercator projection, Zone 18, NAD83

DELAWARE 

BAY

RARITAN

BAY

MARYLAND

EXPLANATION

New Jersey Department of 

Environmental Protection 

Water Region

Passaic

Raritan

Atlantic Coast

Upper Delaware

Lower Delaware

Trend results for dissolved oxygen and 

U.S. Geological Survey station number

01467150 Concentrations decreased

No trend

Not determined

01409416

01411500

A

Figure 4. Trends in (A) year-round concentrations of dissolved oxygen and (B) growing-season (April–September) concentrations 

of dissolved oxygen at water-quality stations on streams in New Jersey, water years 1998–2007.
Trends in the Quality of Water in New Jersey Streams 17

Delaware River

Maurice River

Great Egg Harbor Riv er

Raritan R i v e r

Passaic River

Delaware River

Trenton

Atlantic

City

Philadelphia

New York City

PENNSYLVANIA

DELAWARE

NEW YORK

CONNECTICUT

ATLANTIC OCEAN

75° 74°

41°

40°

39°

Base from U.S. Geological Survey digital line graph files, 1:24,000, 

Universal Transverse Mercator projection, Zone 18, NAD83

DELAWARE 

BAY

RARITAN

BAY

MARYLAND

EXPLANATION

New Jersey Department of 

Environmental Protection 

Water Region

Passaic

Raritan

Atlantic Coast

Upper Delaware

Lower Delaware

Trend results for dissolved oxygen and 

U.S. Geological Survey station number

01410150 Concentrations increased

01466500 Concentrations decreased

No trend

Not determined

01411110

01463850

0 10 20 MILES

0 10 20 KILOMETERS

B

0140940950

01367625

01367770

01367800

01368820

01377000

01378560

01378780

01379200

01380100

01381800

01382000

01382500

01387500

01388500

01389500 01391500

01394500

01395000

01396660

01398000

01398102

01399780

01400000

01400640

01401400

01402000

01403385

01405340

01408000

01408009

01408100

01408500

01408830

01409387

01409416

01409500 01409815

01410150

01411035

01411110

01411196

01411400

01411444

01411466

01411500

01411955

01412800

01438500

01440000

01442760

01443000

01443500

01446400

01457400

01457500

01458570

01461000

01463500

01464020

01464504

01464515

01465893

01466500

01467005

01467150

01467359

01477120

01482500

01463850

Figure 4. Trends in (A) year-round concentrations of dissolved oxygen and (B) growing-season (April–September) concentrations 

of dissolved oxygen at water-quality stations on streams in New Jersey, water years 1998–2007.—Continued
18 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

5

7

9

11

13

15

Dissolved oxygen, in milligrams per liter

7

9

8

9/5/2005 9/6/2005 9/7/2005

pH, in standard units

pH

Dissolved oxygen

EXPLANATION

Figure 5. Values of pH and dissolved oxygen measured continually at the water-quality station on the Delaware 

River at Trenton, N.J. (01463500), September 5–7, 2005.

The consideration of trends in time of measurement was 

included in this study because (1) most of the measurements 

considered in this report were made during the morning or 

early afternoon and (2) dissolved oxygen concentrations measured during this period typically increase with time of day as 

a result of increasing photosynthesis as sunlight increases following sunrise. Values of dissolved oxygen at the water-quality station on the Delaware River at Trenton, N.J. (01463500), 

show this pattern (fig. 5).

The correlation between dissolved oxygen concentrations and time of measurement tends to support the theory that 

increasing photosynthesis during the day has been causing 

increased dissolved oxygen at some stations. Year-round 

concentrations at 11 stations increased with increasing time 

of measurement (table 5a); concentrations did not decrease 

at any station. When growing-season measurements were 

tested, concentrations at 17 stations increased with increasing 

time of measurement (table 5b); concentrations decreased at 2 

stations.

As an example, the result of the trend test of growingseason dissolved oxygen at the station on Flat Brook near 

Flatbrookville, N.J. (01440000), clearly shows the effect of 

a trend in times of measurement. The result of the trend test 

of dissolved oxygen indicates that concentrations decreased 

over the period of study (fig. 6). However, because dissolved 

oxygen concentrations increased with time of measurement 

(table 5b), and the times of measurement decreased over the 

period of study (table 5b), the decrease in dissolved oxygen 

during the period of study can be attributed to the times of 

measurement, which are earlier during the second half of the 

period of study than those during the first half.

Results of trend tests of year-round flow-adjusted values 

of dissolved oxygen determined in this current study and 

the results of corresponding values from Hay and Campbell 

(1990) and Hickman and Barringer (1999) are shown for 

comparison in figure 7 and table 16. Neither of the previous 

studies looked for trends in times of measurement. 
Trends in the Quality of Water in New Jersey Streams 19

10/1/1997 10/1/1999 9/30/2001 10/1/2003 9/30/2005 10/1/2007

2

4

6

8

10

12

14

Dissolved oxygen, in milligrams per liter

0500

0600

0700

0800

0900

1000

1100

1200

Time of measurement

Dissolved-oxygen concentration, in milligrams per liter

Time of measurement

Trend slope for flow-adjusted concentration of dissolved oxygen has a 0.02 level of significance

Trend slope for time of measurement has a 0.0017 level of significance

EXPLANATION

Figure 6. Growing-season concentrations of dissolved oxygen and times of measurement as a function of 

date at the water-quality station on Flat Brook near Flatbrookville, N.J. (01440000), water years 1998–2007.

Figure 7. Fraction of water-quality stations on streams in New Jersey with trends in 

year-round flow-adjusted concentrations of dissolved oxygen during water years 1980–86, 

1986–95, and 1998–2007.

Period of trend analysis, in water years

Fraction of stations with indicated trends,

as a percentage of stations analyzed

1980–1986 1986–1995 1998–2007 0

10

20

30

Stations at which dissolved oxygen decreased over time

Stations at which dissolved oxygen increased over time

Measurements at 

66 stations analyzed 

(this study)

Measurements at 

59 stations analyzed

(Hay and Campbell, 

1990) Measurements at 

81 stations analyzed 

(Hickman and 

Barringer, 1999)

EXPLANATION
20 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Table 16. Results of trend tests on flow-adjusted concentrations of dissolved oxygen during water years 1998–2007 and earlier periods 

at selected water-quality stations on New Jersey streams.

[Stations are listed if results were determined for the current and one previous study; --, no trend in flow-adjusted concentrations of dissolved oxygen during 

the period of study was identified at a 0.05 level of significance; Decrease, dissolved oxygen decreased during the period of study; Increase, dissolved oxygen 

increased during the period of study; n.d., not determined] 

Station 

number Station name

Results of trend analyses on year-round flow-adjusted 

concentrations of dissolved oxygen

Water years 

1980–1986 

(Hay and Campbell, 

1990)1

Water years 

1986–1995 

(Hickman and 

Barringer, 1999)

 Water years 

1998–2007 

(this study)

Passaic Water Region

01377000 Hackensack River at Rivervale, N.J. -- -- --

01381800 Whippany River near Pine Brook, N.J. Increase -- --

01382000 Passaic River at Two Bridges, N.J. n.d. Increase --

01382500 Pequannock River at Macopin Intake Dam, N.J. n.d. -- --

01387500 Ramapo River near Mahwah, N.J. -- -- --

01389500 Passaic River at Little Falls, N.J. -- Increase --

01391500 Saddle River at Lodi, N.J. Decrease -- --

Raritan Water Region

01395000 Rahway River at Rahway, N.J. -- -- --

01396660 Mulhockaway Creek at Van Syckel, N.J. -- -- --

01398000 Neshanic River at Reaville, N.J. Increase -- --

01399780 Lamington River at Burnt Mills, N.J. Increase Increase --

01402000 Millstone River at Blackwells Mills, N.J. n.d. -- --

01405340 Manalapan Brook at Federal Road near Manalapan, N.J. -- -- --

Atlantic Coastal Water Region

01408000 Manasquan River at Squankum, N.J. n.d. -- --

01408500 Toms River near Toms River, N.J. -- -- --

01409387 Mullica River at outlet of Atsion Lake at Atsion, N.J. -- -- --

01409416 Hammonton Creek at Wescoatville, N.J. -- -- --

01409500 Batsto River at Batsto, N.J. -- -- --

01409815 West Branch Wading River at Maxwell, N.J. -- n.d. --

01410150 East Branch Bass River near New Gretna, N.J. Increase Decrease --

01411110 Great Egg Harbor River at Weymouth, N.J. n.d. -- --

Upper Delaware Water Region

01367770 Wallkill River near Sussex, N.J. -- -- --

01438500 Delaware River at Montague, N.J. n.d. -- Decrease

01443000 Delaware River at Portland, Pa. n.d. -- --

01443500 Paulins Kill at Blairstown, N.J. -- -- --

01457400 Musconetcong River at Riegelsville, N.J. n.d. -- --

01457500 Delaware River at Riegelsville, N.J. n.d. -- Decrease

01461000 Delaware River at Lumberville, Pa. n.d. -- --

01463500 Delaware River at Trenton, N.J. -- -- --

Lower Delaware Water Region

01412800 Cohansey River at Seeley, N.J. -- -- --

01464515 Doctors Creek at Allentown, N.J. n.d. -- --

01466500 McDonalds Branch in Byrne State Forest, N.J. -- -- --

01467150 Cooper River at Haddonfield, N.J. n.d. -- Decrease

01477120 Raccoon Creek near Swedesboro, N.J. -- -- --

01482500 Salem River at Woodstown, N.J. -- -- -- 1

 Although Hay and Campbell (1990) considered trends to be significant at the 0.1 level, trends significant at the 0.05 level were identified in their report.
Trends in the Quality of Water in New Jersey Streams 21

pH

Results of trend tests of pH were determined for 26 stations (table 7; fig. 8). Decreases in value were identified at two 

stations; the slopes of these trends fall in the range of -0.019 

to -0.028 pH units per year (-0.3 to -0.4 percent of median pH 

per year). Increases in values were identified at three stations; 

the slopes of these trends fall in the range of 0.017 to 0.069 pH 

units per year (0.2 to 0.9 percent of median pH per year). 

Summary statistics for pH are listed in table 6. 

Results of trend tests of pH are not presented for 

ASWQMN stations sampled by USGS personnel because an 

examination of time-series plots of pH values measured by 

USGS personnel indicated a step decrease near the start of 

water year 2002, which is apparently related to the change in 

USGS field methods previously discussed. The existence of 

this step decrease was verified by the results of a rank-sum test 

to compare values of pH measured prior to October 1, 2001, 

at a station to pH values at that station following that date. 

Results of these tests indicate that, at the 43 stations sampled 

by USGS personnel (other than 01463500), pH values following October 1, 2001, were less than prior pH values at 26 

stations (60 percent) and greater than prior pH values at 0 stations. The results for the same tests at the 26 stations sampled 

by NJDEP personnel were quite different; pH values following 

October 1, 2001, were less than prior pH values at two stations 

(8 percent) and greater than prior pH values at two stations 

(8 percent). In response to this analysis, results of trend tests 

of pH for USGS-sampled stations (other than 01463500) were 

set to “n.d.” (table 7).

Results of the trend test in pH at the station on the Cooper River at Haddonfield, N.J. (01467150) are not reported 

because they were affected by a trend in time of measurement 

(table 7). Values of pH, like those of dissolved oxygen, typically vary diurnally because of the effects of photosynthesis 

(see figure 6 as an example). The effect of a trend in time of 

measurement on results of trends in pH values was examined 

as previously described for dissolved oxygen. The station on 

the Cooper River was the only station sampled by NJDEP at 

which there was a trend in time of pH measurement and a correlation between time of measurement and pH value.

Results of this study and those of previous studies are 

shown in figure 9 and table 17 for comparison. The fraction of 

stations with trends in pH during water years 1998–2007 was 

greater than the fraction of stations identified as having trends 

in the two previous studies (fig. 9). The number of stations 

analyzed for trends in pH in this study is far fewer than the 

number analyzed in the previous studies. 

Total Dissolved Solids

Results of trend tests of total dissolved solids are 

reported for all 70 stations. Trends were identified at 24 

stations (table 9; figure 10). All trends indicate increasing 

concentrations during the period of study; the slopes of these 

trends range from 0.6 to 12.9 milligrams per liter per year 

(0.9 to 5.3 percent of median concentrations). Increasing 

concentrations were identified at both stations (01394500 and 

01395000) on the Rahway River. Summary statistics for total 

dissolved solids are listed in table 8.

Results of trend analysis of measurements of dissolved 

solids in this study and those of previous studies (Hay and 

Campbell, 1990; Hickman and Barringer, 1999) are shown 

in figure 11 for comparison. The fraction of stations at which 

concentrations of total dissolved solids increased during water 

years 1998–2007 (34 percent) is greater than the corresponding fraction of stations with increasing concentrations during 

water years 1980–86 (24 percent) and water years 1986–95 

(26 percent). The trend tests for water years 1980–86 were 

conducted on the sums of dissolved solids, which are very 

similar to values of total dissolved solids. Results of trend tests 

for individual stations are presented in table 18.
22 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Delaware River

Maurice River

Great Egg Harbor Riv er

Raritan R i v e r

Passaic River

Delaware River

0140940950

01367625

01367770

01367800

01368820

01377000

01378560

01378780

01379200

01380100

01381800

01382000

01382500

01387500

01388500

01389500 01391500

01394500

01395000

01396660

01398000

01398102

01399780

01400000

01400640

01401400

01402000

01403385

01405340

01408000

01408009

01408100

01408500

01408830

01409387

01409416

01409500 01409815

01410150

01411035

01411110

01411196

01411400

01411444

01411466

01411500

01411955

01412800

01438500

01440000

01442760

01443000

01443500

01446400

01457400

01457500

01458570

01461000

01463500

01464020

01464504

01464515

01465893

01466500

01467005

01467150

01467359

01477120

01482500

01463850

Trenton

Atlantic

City

Philadelphia

New York City

PENNSYLVANIA

DELAWARE

NEW YORK

CONNECTICUT

ATLANTIC OCEAN

75° 74°

41°

40°

39°

0 10 20 MILES

0 10 20 KILOMETERS

Base from U.S. Geological Survey digital line graph files, 1:24,000, 

Universal Transverse Mercator projection, Zone 18, NAD83

DELAWARE 

BAY

RARITAN

BAY

MARYLAND

EXPLANATION

New Jersey Department of 

Environmental Protection 

Water Region

Passaic

Raritan

Atlantic Coast

Upper Delaware

Lower Delaware

Trend results for pH and U.S. 

Geological Survey station number

01408500 Values increased

01438500 Values decreased

No trend

Not determined

01402000

01465893

Figure 8. Trends in pH at water-quality stations on streams in New Jersey, water years 1998–2007.
Trends in the Quality of Water in New Jersey Streams 23

Figure 9. Fraction of water-quality 

stations on streams in New Jersey with 

trends in flow-adjusted values of pH 

during water years 1980–86, 1986–95, 

and 1998–2007.

Table 17. Results of trend tests on flow-adjusted values of pH during water years 1998–2007 and earlier periods at selected waterquality stations on New Jersey streams.

[Stations are listed if results were determined for the current and one previous study; --, no trend in flow-adjusted values of pH during the period of study was 

identified at a 0.05 level of significance; Decrease, pH values decreased during the period of study; Increase, pH values increased during the period of study; 

n.d., not determined] 

Station 

number Station name

Results of trend tests on flow-adjusted values of pH

Water years 

1980–1986 

(Hay and Campbell, 

1990)1

Water years 

1986–1995 

(Hickman and 

Barringer, 1999)

Water years 

1998–2007 

(this study)

Passaic Water Region

01377000 Hackensack River at Rivervale, N.J. -- -- --

01381800 Whippany River near Pine Brook, N.J. -- -- --

01382500 Pequannock River at Macopin Intake Dam, N.J. n.d. -- --

01387500 Ramapo River near Mahwah, N.J. Increase -- --

01391500 Saddle River at Lodi, N.J. -- -- --

Raritan Water Region

01394500 Rahway River near Springfield, N.J. -- -- Increase

01395000 Rahway River at Rahway, N.J. -- -- --

01396660 Mulhockaway Creek at Van Syckel, N.J. -- Increase --

01398000 Neshanic River at Reaville, N.J. Increase -- --

01402000 Millstone River at Blackwells Mills, N.J. n.d. Increase --

Atlantic Coastal Water Region

01408000 Manasquan River at Squankum, N.J. n.d. -- Decrease

01408500 Toms River near Toms River, N.J. -- Increase Increase

01410150 East Branch Bass River near New Gretna, N.J. -- -- --

Upper Delaware Water Region

01438500 Delaware River at Montague, N.J. n.d. -- Decrease

01440000 Flat Brook near Flatbrookville, N.J. n.d. -- --

01443500 Paulins Kill at Blairstown, N.J. -- -- --

01457500 Delaware River at Riegelsville, N.J. n.d. -- --

01461000 Delaware River at Lumberville, Pa. n.d. -- Increase

01463500 Delaware River at Trenton, N.J. -- -- --

Lower Delaware Water Region

01411500 Maurice River at Norma, N.J. -- -- --

01466500 McDonalds Branch in Byrne State Forest, N.J. -- -- --

01477120 Raccoon Creek near Swedesboro, N.J. Decrease -- --

01482500 Salem River at Woodstown, N.J. -- -- -- 1

 Although Hay and Campbell (1990) considered trends to be significant at the 0.1 level, trends significant at the 0.05 level were identified in their report.

Period of trend analysis, in water years

Fraction of stations with indicated trends,

as a percentage of stations analyzed

1980–1986 1986–1995 1998–2007 0

10

20

30

40

50

Stations at which pH decreased over time

Stations at which pH increased over time

Measurements at 

26 stations analyzed 

Measurements at (this study)

59 stations analyzed

(Hay and Campbell, 

1990)

Measurements at 

81 stations analyzed 

(Hickman and 

Barringer, 1999)

EXPLANATION
24 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Delaware River

Maurice River

Great Egg Harbor Riv er

Raritan R i v e r

Passaic River

Delaware River

0140940950

01367625

01367770

01367800

01368820

01377000

01378560

01378780

01379200

01380100

01381800

01382000

01382500

01387500

01388500

01389500 01391500

01394500

01395000

01396660

01398000

01398102

01399780

01400000

01400640

01401400

01402000

01403385

01405340

01408000

01408009

01408100

01408500

01408830

01409387

01409416

01409500 01409815

01410150

01411035

01411110

01411196

01411400

01411444

01411466

01411500

01411955

01412800

01438500

01440000

01442760

01443000

01443500

01446400

01457400

01457500

01458570

01461000

01463500

01464020

01464504

01464515

01465893

01466500

01467005

01467150

01467359

01477120

01482500

01463850

Trenton

Atlantic 

City

Philadelphia

New York City

PENNSYLVANIA

DELAWARE

NEW YORK

CONNECTICUT

ATLANTIC OCEAN

75° 74°

41°

40°

39°

0 10 20 MILES

0 10 20 KILOMETERS

Base from U.S. Geological Survey digital line graph files, 1:24,000, 

Universal Transverse Mercator projection, Zone 18, NAD83

DELAWARE 

BAY

RARITAN

BAY

MARYLAND

EXPLANATION

New Jersey Department of 

Environmental Protection 

Water Region

Passaic

Raritan

Atlantic Coast

Upper Delaware

Lower Delaware

Trend results for total dissolved 

solids and U.S. Geological Survey 

station number

01411400 Concentrations increased

01409387 No trend

Figure 10. Trends in concentrations of total dissolved solids at water-quality stations on streams in New Jersey, water 

years 1998–2007.
Trends in the Quality of Water in New Jersey Streams 25

Table 18. Results of trend tests on flow-adjusted concentrations of dissolved solids during water years 1998–2007 and earlier periods 

at selected water-quality stations on New Jersey streams.

[Stations are listed if results were determined for the current and one previous study; --, no trend in flow-adjusted concentrations of dissolved solids during the 

period of study was identified at a 0.05 level of significance; Decrease, concentrations of dissolved solids decreased during the period of study; Increase, concentrations of dissolved solids increased during the period of study; n.d., not determined] 

Station 

number Station name

Results of trend tests on flow-adjusted concentrations 

of dissolved solids

Sum of dissolved 

constituents, 

water years 

1980–1986 

(Hay and Campbell, 

1990)1

Total dissolved 

solids, 

water years 

1986–1995 

(Hickman and 

Barringer, 1999)

Total dissolved 

solids, 

water years 

1998–2007 

(this study)

Passaic Water Region

01377000 Hackensack River at Rivervale, N.J. n.d. -- --

01381800 Whippany River near Pine Brook, N.J. n.d. -- Increase

01382000 Passaic River at Two Bridges, N.J. n.d. Increase --

01387500 Ramapo River near Mahwah, N.J. n.d. -- --

01389500 Passaic River at Little Falls, N.J. -- Increase --

01391500 Saddle River at Lodi, N.J. n.d. -- Increase

Raritan Water Region

01394500 Rahway River near Springfield, N.J. n.d. -- Increase

01395000 Rahway River at Rahway, N.J. n.d. -- Increase

01396660 Mulhockaway Creek at Van Syckel, N.J. -- Increase --

01398000 Neshanic River at Reaville, N.J. -- -- --

01399780 Lamington River at Burnt Mills, N.J. -- -- Increase

01405340 Manalapan Brook at Federal Road near Manalapan, N.J. -- -- Increase

Atlantic Coastal Water Region

01408500 Toms River near Toms River, N.J. -- n.d. Increase

01409416 Hammonton Creek at Wescoatville, N.J. -- -- Increase

01409500 Batsto River at Batsto, N.J. -- Decrease --

01409815 West Branch Wading River at Maxwell, N.J. -- n.d. --

01410150 East Branch Bass River near New Gretna, N.J. -- n.d. Increase

01411110 Great Egg Harbor River at Weymouth, N.J. n.d. -- Increase

Upper Delaware Water Region

01367770 Wallkill River near Sussex, N.J. Increase -- --

01443000 Delaware River at Portland, Pa. n.d. -- --

01443500 Paulins Kill at Blairstown, N.J. Increase -- --

01457400 Musconetcong River at Riegelsville, N.J. n.d. Increase --

01461000 Delaware River at Lumberville, Pa. n.d. -- --

01463500 Delaware River at Trenton, N.J. Increase -- --

Lower Delaware Water Region

01411500 Maurice River at Norma, N.J. -- -- --

01412800 Cohansey River at Seeley, N.J. -- Increase --

01464515 Doctors Creek at Allentown, N.J. n.d. -- --

01466500 McDonalds Branch in Byrne State Forest, N.J. -- n.d. --

01477120 Raccoon Creek near Swedesboro, N.J. -- -- Increase

01482500 Salem River at Woodstown, N.J. -- -- Increase

1

 Although Hay and Campbell (1990) considered trends to be significant at the 0.1 level, trends significant at the 0.05 level were identified in their report.
26 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Trends determined from Tobit Regression

Trends in flow-adjusted values of total phosphorus, total 

organic nitrogen plus ammonia, and dissolved nitrate plus 

nitrite were identified by use of tests with Tobit regression. 

For measurements of each water-quality characteristic at each 

station, the result presented is that of either the test with all 

water-quality measurements or the test with all measurements 

except the extreme outlier. If the results of the two tests were 

equivalent—either no trend, increasing values of water quality, 

or decreasing values of water quality, the result presented is 

from the test with all measurements. If the results of the two 

tests were not equivalent, the result presented is that from the 

test without the extreme outlier.

Tests were conducted with and without the most extreme 

outlier for two reasons. First, an extreme outlier may cause the 

residuals from the Tobit regression to be unevenly distributed, 

and the results of the regression are likely to be less accurate 

the less evenly distributed the residuals are. Second, this 

approach reduces the probability that the identification of a 

trend is due only to the influence of a single extreme outlier.

As an example, the application of Tobit regression to all 

measurements of total organic nitrogen plus ammonia at the 

water-quality station on the Pequannock River at the Macopin 

Intake Dam (01382500) is shown in figures 12A and 12B. 

Measured concentrations as a function of concentrations 

predicted with the equation produced by Tobit regression are 

shown in figure 12A.

The result of the Tobit regression trend test indicates 

that flow-adjusted concentrations of total organic nitrogen 

plus ammonia at the water-quality station on the Pequannock 

River at the Macopin Intake Dam (01382500) increased during the period of study (table 13). The level of significance 

of the trend slope (0.001) is the level of significance of the 

coefficient for “Year” in equation 4. The trend slope for the 

flow-adjusted concentrations was determined to be 0.036 milligrams per liter as nitrogen (N) per year from the value of the 

coefficient for “Year” from equation 4 (0.0915) and equation 5. Given that the level of significance of the trend slope 

is less than 0.05, flow-adjusted concentrations of total organic 

nitrogen plus ammonia at this station (01382500) increased 

during the period of study at the rate of change indicated by 

the trend slope. Measured concentrations, the concentrations 

predicted with equation 4, and the trend slope as a function of 

date are shown in figure 12B. 

Total Phosphorus

Results of trend tests of total phosphorus are reported 

for 69 stations (table 11 and fig. 13). A trend test was not 

conducted on values of total phosphorus at the water-quality 

station on McDonalds Branch in Byrne State Forest, N.J. 

(01466500), because there were an insufficient number of 

uncensored or estimated concentrations. Summary statistics 

for total phosphorus are listed in table 10.

Trends in total phosphorus concentration over the period 

of study were identified at 17 stations (table 11). Decreasing 

concentrations were identified for 12 stations; the slopes for 

these trends range from -0.001 to -0.055 milligrams per liter as 

phosphorus (P) per year (-3.0 to -12.1 percent of mean concentrations per year). Increasing concentrations were identified 

for five stations; slopes for these trends range from 0.002 to 

0.011 milligrams per liter as P per year (5.9 to 8.6 percent of 

mean concentrations per year).

For two reaches with two or more stations each, decreasing concentrations of total phosphorus over the period 

Figure 11. Fraction of water-quality stations with trends in flow-adjusted concentrations 

of dissolved solids during water years 1980–86, 1986–95, and 1998–2007.

Period of trend analysis, in water years

Fraction of stations with indicated trends,

as a percentage of stations analyzed

1980-1986 1986-1995 1998-2007

0

10

20

30

40

50

Measurements of total

dissolved solids at 70 stations

analyzed (this study) Measurements of the sum 

of dissolved constituents at 

33 stations analyzed

(Hay and Campbell, 1990)

Measurements of total 

dissolved solids at 61 

stations analyzed (Hickman 

and Barringer, 1999)

Stations at which dissolved solids decreased over time

Stations at which dissolved solids increased over time

EXPLANATION
Trends in the Quality of Water in New Jersey Streams 27

10/1/1997 10/1/1999 9/30/2001 10/1/2003 9/30/2005 10/1/2007

0.0

0.5

1.0

1.5

2.0

Total organic nitrogen plus ammonia,

in milligrams per liter as N 

(B)

Measured uncensored concentration

EXPLANATION

Measured nondetect concentration

Concentration predicted with equation from Tobit regression

Trend slope for flow-adjusted concentrations

The trend slope for flow-adjusted concentrations is 0.036 milligrams per liter

as N per year at a 0.001 level of significance 

Predicted concentration of total organic nitrogen plus ammonia,

in milligrams per liter as N

0.1

1.0

10.0

0.2

0.3

0.4

0.5

0.7

2.0

3.0

4.0

5.0

7.0

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0. 9 1.0

Measured concentration of total organic nitrogen

plus ammonia, in milligrams per liter as N 

Measured uncensored concentration

EXPLANATION

Measured nondetect concentration

Concentration predicted with equation from Tobit regression

(A)

Figure 12. Results of trend analysis with Tobit regression for total organic nitrogen plus ammonia at the water-quality station 

on the Pequannock River at the Macopin Intake Dam, N.J. (01382500), water years 1998–2007, (A) measured concentrations 

as a function of predicted concentrations and (B) measured and predicted concentrations and trend slope as a function of 

date.
28 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

of study were identified (table 11 and fig. 13). One reach 

extends from the station on the Whippany River near Pine 

Brook, N.J. (01381800), to the station on the Passaic River 

at Two Bridges, N.J. (01382000); decreasing concentrations 

were identified at both stations. The other reach is the Delaware River; four of the five stations were identified as having decreasing concentrations. These stations are located at 

Montague, N.J. (01438500), Riegelsville, N.J. (01457500), 

Lumberville, Pa. (01461000), and Trenton, N.J. (01463500).

The fraction of stations with trends in total phosphorus 

during water years 1998–2007 was smaller than the fraction 

of stations with trends during water years 1986–95 (fig. 14). 

Results for only those stations included in both studies are 

listed in table 19. Corresponding values for water years 

1980–86 are not available.

Total Organic Nitrogen plus Ammonia

Results of trend tests of total organic nitrogen plus 

ammonia are reported for 69 stations (table 13 and fig. 15). 

Results for the water-quality station on Dunnfield Creek at 

Dunnfield, N.J. (01442760), are not presented because an 

insufficient number of uncensored or estimated values were 

available. Summary statistics for total organic nitrogen plus 

ammonia are listed in table 12.

Trends in concentrations of total organic nitrogen plus 

ammonia were identified at 15 stations (table 13). Concentrations decreased over the period of study at six stations; the 

slopes of these trends range from -0.008 to -0.093 milligrams 

per liter as N per year (-2.5 to -11.1 percent of mean values 

per year) (table 13; fig. 15). Concentrations increased during 

the period of study at nine stations; the slopes of these trends 

range from 0.005 to 0.041 milligrams per liter as N per year 

(1.8 to 11.4 percent of mean values per year).

The fraction of stations with trends in total organic nitrogen plus ammonia during water years 1998–2007 and those 

from previous studies of total organic nitrogen during water 

years 1980–86 and total organic nitrogen plus ammonia during 

water years 1986–95 are shown in figure 16. Concentrations of 

total organic nitrogen typically are similar to concentrations of 

total organic nitrogen plus ammonia at many stations. Results 

of trend analyses for individual stations included in this and in 

one or more of the two previous studies are listed in table 20. 

Dissolved Nitrate plus Nitrite

Of the 70 stations, results of trend tests of dissolved 

nitrate plus nitrite are presented for 66 (table 15; fig. 17). 

Trend tests were not conducted on four stations because an 

insufficient number of uncensored concentrations were available. Summary statistics for dissolved nitrate plus nitrite are 

listed in table 14.

Trends indicating decreasing concentrations during the 

period of study were identified at four stations (table 15; 

fig. 17); slopes of these trends range from -0.009 to 

-0.256 milligrams per liter as N per year (-3.1 to -6.7 percent of mean values per year). Trends indicating increasing 

concentrations during the period of study were identified at 19 

stations; slopes of these trends range from 0.009 to 0.117 milligrams per liter as N per year (2.2 to 8 percent of mean values 

per year). 

The fraction of stations with trends in dissolved nitrate 

plus nitrite during water years 1998–2007 and the fraction of 

stations with trends in total nitrate during water years 1986–95 

(Hickman and Barringer, 1999) are shown in figure 18. 

Concentrations of total nitrate are likely to be close to concentrations of dissolved nitrate plus nitrite. Results for stations 

included in this study and in Hickman and Barringer (1999) 

are listed in table 21.

Summary of Trends by Station

A summary of the results for the six water-quality characteristics are presented in table 22 (at end of report) so that the 

reader can compare the results of all water-quality characteristics at a station. The table includes the results of tests of both 

year-round and growing-season values of dissolved oxygen.
Trends in the Quality of Water in New Jersey Streams 29

Figure 13. Trends in concentrations of total phosphorus at water-quality stations on streams in New Jersey, water years 

1998–2007.

Delaware River

Maurice River

Great Egg Harbor Riv er

Raritan R i v e r

Passaic River

Delaware River

0140940950

01367625

01367770

01367800

01368820

01377000

01378560

01378780

01379200

01380100

01381800

01382000

01382500

01387500

01388500

01389500 01391500

01394500

01395000 01396660

01398000

01398102

01399780

01400000

01400640

01401400

01402000

01403385

01405340

01408000

01408009

01408100

01408500

01408830

01409387

01409416

01409500 01409815

01410150

01411035

01411110

01411196

01411400

01411444

01411466

01411500

01411955

01412800

01438500

01440000

01442760

01443000

01443500

01446400

01457400

01457500

01458570

01461000

01463500

01464020

01464504

01464515

01465893

01466500

01467005

01467150

01467359

01477120

01482500

01463850

Trenton

Atlantic

City

Philadelphia

New York City

PENNSYLVANIA

DELAWARE

NEW YORK

CONNECTICUT

ATLANTIC OCEAN

75° 74°

41°

40°

39°

0 10 20 MILES

0 10 20 KILOMETERS

Base from U.S. Geological Survey digital line graph files, 1:24,000, 

Universal Transverse Mercator projection, Zone 18, NAD83

DELAWARE 

BAY

RARITAN

BAY

MARYLAND

EXPLANATION

New Jersey Department of 

Environmental Protection 

Water Region

Passaic

Raritan

Atlantic Coast

Upper Delaware

Lower Delaware

Trend results for total phosphorus and 

U.S. Geological Survey station number

01411400 Concentrations increased

01408500 Concentrations decreased

No trend

Not determined

01409387

01466500
30 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Figure 14. Fraction of water-quality stations with trends 

in flow-adjusted concentrations of total phosphorus during 

water years 1986–95 and 1998–2007.

Table 19. Results of trend tests on flow-adjusted concentrations of total phosphorus during water years 

1998–2007 and water years 1986–1995 at selected water-quality stations on New Jersey streams.

[Stations are listed if results were determined for the current and the previous study; --, no trend in flow-adjusted concentrations of total 

phosphorus during the period of study was identified at a 0.05 level of significance; Decrease, total phosphorus decreased during the 

period of study] 

Station 

number Station name

Results of trend tests on flow-adjusted 

concentrations of total phosphorus

Water years 

1986–1995 

(Hickman and 

Barringer, 1999)

Water years 

1998–2007 

(this study)

Passaic Water Region

01377000 Hackensack River at Rivervale, N.J. -- --

01381800 Whippany River near Pine Brook, N.J. Decrease Decrease

01382000 Passaic River at Two Bridges, N.J. -- Decrease

01387500 Ramapo River near Mahwah, N.J. -- --

01389500 Passaic River at Little Falls, N.J. -- --

01391500 Saddle River at Lodi, N.J. Decrease --

Raritan Water Region

01394500 Rahway River near Springfield, N.J. -- --

01395000 Rahway River at Rahway, N.J. -- --

01398000 Neshanic River at Reaville, N.J. -- --

01399780 Lamington River at Burnt Mills, N.J. -- --

01402000 Millstone River at Blackwells Mills, N.J. -- --

01405340 Manalapan Brook at Federal Road near Manalapan, N.J. -- --

Atlantic Coastal Water Region

01408000 Manasquan River at Squankum, N.J. -- --

01409416 Hammonton Creek at Wescoatville, N.J. Decrease --

Upper Delaware Water Region

01457500 Delaware River at Riegelsville, N.J. -- Decrease

01461000 Delaware River at Lumberville, Pa. -- Decrease

01463500 Delaware River at Trenton, N.J. -- Decrease

Lower Delaware Water Region

01464515 Doctors Creek at Allentown, N.J. Decrease --

01467150 Cooper River at Haddonfield, N.J. Decrease --

01477120 Raccoon Creek near Swedesboro, N.J. -- --

01482500 Salem River at Woodstown, N.J. -- --

1986–1995 1998–2007

0

10

20

30

40

50

70

60

Period of trend analysis, in water years

Fraction of stations with indicated trends,

as a percentage of stations analyzed

Measurements at 

51 stations analyzed 

(Hickman and 

Barringer, 1999)

Measurements at 

69 stations analyzed 

(this study)

Stations at which total phosphorus 

decreased over time

Stations at which total phosphorus 

increased over time

EXPLANATION
Trends in the Quality of Water in New Jersey Streams 31

Delaware River

Maurice River

Great Egg Harbor Riv er

Raritan R i v e r

Passaic River

D elaware River

0140940950

01367625

01367770

01367800

01368820

01377000

01378560

01378780

01379200

01380100

01381800

01382000

01382500

01387500

01388500

01389500 01391500

01394500

01395000

01396660

01398000

01398102

01399780

01400000

01400640

01401400

01402000

01403385

01405340

01408000

01408009

01408100

01408500

01408830

01409387

01409416

01409500 01409815

01410150 01411035

01411110

01411196

01411400

01411444

01411466

01411500

01412800

01438500

01440000

01442760

01443000

01443500

01446400

01457400

01457500

01458570

01461000

01463500

01464020

01464504

01464515

01465893 01466500

01467005

01467150

01467359

01477120

01482500

01463850

01411955

Trenton

Atlantic

City

Philadelphia

New York City

PENNSYLVANIA

DELAWARE

NEW YORK

CONNECTICUT

ATLANTIC OCEAN

75° 74°

41°

40°

39°

0 10 20 MILES

0 10 20 KILOMETERS

Base from U.S. Geological Survey digital line graph files, 1:24,000, 

Universal Transverse Mercator projection, Zone 18, NAD83

DELAWARE 

BAY

RARITAN

BAY

MARYLAND

EXPLANATION

New Jersey Department of 

Environmental Protection 

Water Region

Passaic

Raritan

Atlantic Coast

Upper Delaware

Lower Delaware

Trend results for total organic nitrogen 

plus ammonia and U.S. Geological 

Survey station number

01411110 Concentrations increased

01389500 Concentrations decreased

No trend

Not determined

01411196

01442760

Figure 15. Trends in concentrations of total organic nitrogen plus ammonia at water-quality stations on streams in New 

Jersey, water years 1998–2007.
32 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Figure 16. Fraction of water-quality stations with trends in flow-adjusted concentrations of 

organic nitrogen compounds during water years 1980–86, 1986–95, and 1998–2007.

Period of trend analysis, in water years

Fraction of stations with indicated trends,

as a percentage of stations analyzed

1980–1986 1986–1995 1998–2007

0

20

40

60

80

100

Stations at which concentration 

of organic nitrogen compounds 

decreased over time

Stations at which concentration 

of organic nitrogen compounds 

increased over time

Measurements of total

organic nitrogen plus

ammonia at 69 stations 

analyzed (this study)

Measurements of total 

organic nitrogen at 

50 stations analyzed

(Hay and Campbell, 1990)

Measurements of total 

organic nitrogen at 80 stations 

analyzed (Hickman and 

Barringer, 1999)

EXPLANATION
Trends in the Quality of Water in New Jersey Streams 33

Table 20. Results of trend tests on flow-adjusted concentrations of organic nitrogen compounds during water years 1998–2007 and 

earlier periods at selected water-quality stations on New Jersey streams.

[Stations are listed if results were determined for the current and one previous study; --, no trend in flow-adjusted concentrations of organic nitrogen compound 

during the period of study was identified at a 0.05 level of significance; Decrease, concentrations of organic nitrogen compound decreased during the period of 

study; Increase, concentrations of organic nitrogen compound increased during the period of study; n.d., not determined] 

Station 

number Station name

Results of trend tests on flow-adjusted concentrations 

of organic nitrogen compounds

Total organic nitrogen, 

water years 

1980–1986 

(Hay and Campbell, 

1990)1

Total organic nitrogen, 

water years 

1986–1995 

(Hickman and 

Barringer, 1999)

Total organic nitrogen 

plus ammonia, 

water years 

1998–2007 

(this study)

Passaic Water Region

01377000 Hackensack River at Rivervale, N.J. -- Decrease --

01381800 Whippany River near Pine Brook, N.J. n.d. -- --

01382000 Passaic River at Two Bridges, N.J. n.d. Decrease --

01382500 Pequannock River at Macopin Intake Dam, N.J. n.d. -- Increase

01387500 Ramapo River near Mahwah, N.J. -- -- --

01389500 Passaic River at Little Falls, N.J. -- Decrease Decrease

01391500 Saddle River at Lodi, N.J. -- -- Decrease

Raritan Water Region

01394500 Rahway River near Springfield, N.J. -- Decrease --

01395000 Rahway River at Rahway, N.J. -- -- --

01396660 Mulhockaway Creek at Van Syckel, N.J. -- Decrease --

01398000 Neshanic River at Reaville, N.J. -- Decrease --

01399780 Lamington River at Burnt Mills, N.J. n.d. Decrease --

01402000 Millstone River at Blackwells Mills, N.J. n.d. Decrease --

01405340 Manalapan Brook at Federal Road near Manalapan, N.J. n.d. Decrease --

Atlantic Coastal Water Region

01408000 Manasquan River at Squankum, N.J. n.d. Decrease Increase

01408500 Toms River near Toms River, N.J. -- Decrease --

01409387 Mullica River at outlet of Atsion Lake at Atsion, N.J. n.d. Decrease --

01409416 Hammonton Creek at Wescoatville, N.J. -- Decrease --

01409500 Batsto River at Batsto, N.J. -- Decrease --

01410150 East Branch Bass River near New Gretna, N.J. -- -- --

01411110 Great Egg Harbor River at Weymouth, N.J. n.d. -- Increase

Upper Delaware Water Region

01367770 Wallkill River near Sussex, N.J. -- -- --

01438500 Delaware River at Montague, N.J. n.d. -- --

01440000 Flat Brook near Flatbrookville, N.J. n.d. -- --

01443000 Delaware River at Portland, Pa. n.d. -- Increase

01443500 Paulins Kill at Blairstown, N.J. Decrease Decrease Decrease

01457400 Musconetcong River at Riegelsville, N.J. n.d. Decrease Decrease

01457500 Delaware River at Riegelsville, N.J. n.d. Decrease --

01461000 Delaware River at Lumberville, Pa. n.d. Decrease --

01463500 Delaware River at Trenton, N.J. -- Decrease --

Lower Delaware Water Region

01411500 Maurice River at Norma, N.J. -- Decrease Increase

01412800 Cohansey River at Seeley, N.J. -- Decrease --

01464515 Doctors Creek at Allentown, N.J. n.d. -- --

01467150 Cooper River at Haddonfield, N.J. n.d. Decrease Increase

01477120 Raccoon Creek near Swedesboro, N.J. -- Decrease --

01482500 Salem River at Woodstown, N.J. -- Decrease --

01477120 Raccoon Creek near Swedesboro, N.J. -- Decrease --

01482500 Salem River at Woodstown, N.J. -- Decrease -- 1

 Although Hay and Campbell (1990) considered trends to be significant at the 0.1 level, trends significant at the 0.05 level were identified in their report.
34 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Delaware River

Maurice River

Great Egg Harbor Riv er

Raritan R i v e r

Passaic River

Delaware River

Trenton

Atlantic

City

Philadelphia

New York City

PENNSYLVANIA

DELAWARE

NEW YORK

CONNECTICUT

ATLANTIC OCEAN

75° 74°

41°

40°

39°

0 10 20 MILES

0 10 20 KILOMETERS

Base from U.S. Geological Survey digital line graph files, 1:24,000, 

Universal Transverse Mercator projection, Zone 18, NAD83

DELAWARE 

BAY

RARITAN

BAY

MARYLAND

EXPLANATION

New Jersey Department of 

Environmental Protection 

Water Region

Passaic

Raritan

Atlantic Coast

Upper Delaware

Lower Delaware

Trend results for dissolved nitrate plus

nitrite and U.S. Geological Survey

station number

01412800 Concentrations increased

01411035 Concentrations decreased

No trend

Not determined

01477120

01409815

0140940950

01367625

01367770

01367800 01368820

01377000

01378560

01378780

01379200

01380100

01381800

01382000

01382500

01387500

01388500

01389500 01391500

01394500

01395000

01396660

01398000

01398102

01399780

01400000

01400640

01401400

01402000

01403385

01405340

01408000

01408009

01408100

01408500

01408830

01409387

01409416

01409500 01409815

01410150

01411035

01411110

01411196

01411400

01411444

01411466

01411500

01411955

01412800

01438500

01440000

01442760

01443000

01443500

01446400

01457400

01457500

01458570

01461000

01463500

01464020

01464504

01464515

01465893

01466500

01467005

01467150

01467359

01477120

01482500

01463850

Figure 17. Trends in concentrations of dissolved nitrate plus nitrite at water-quality stations on streams in New Jersey, 

water years 1998–2007.
Trends in the Quality of Water in New Jersey Streams 35

Figure 18. Fraction of water-quality stations with trends in flowadjusted concentrations of nitrate compounds during water years 

1986–95 and 1998–2007.

1986–1995 1998–2007

0

10

20

30

40

50

60

Period of trend analysis, in water years

Fraction of stations with indicated trends,

as a percentage of stations analyzed

Measurements of total nitrate

at 73 stations analyzed 

(Hickman and Barringer, 1999)

Measurements of dissolved 

nitrate plus nitrite at 66 stations 

analyzed (this study)

Stations at which concentration of nitrate

compounds decreased over time

Stations at which concentration of nitrate 

compounds increased over time

EXPLANATION
36 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Table 21. Results of trend tests on flow-adjusted concentrations of nitrate compounds during water years 

1998–2007 and water years 1986–1995 at selected water-quality stations on New Jersey streams.

[Stations are listed if results were determined for the current and previous study; --, no trend in flow-adjusted concentrations of the 

nitrate compound during the period of study was identified at a 0.05 level of significance; Decrease, nitrate compound decreased during 

the period of study; Increase, nitrate compound increased during the period of study; n.d., not determined]

Station 

number Station name

Results of trend tests on flow-adjusted 

concentrations of nitrate compounds

Total nitrate, 

water years 

1986–1995 

(Hickman and 

Barringer, 1999)

Dissolved nitrate 

plus nitrite, 

water years 

1998–2007 

(this study)

Passaic Water Region

01377000 Hackensack River at Rivervale, N.J. -- --

01381800 Whippany River near Pine Brook, N.J. Increase --

01382000 Passaic River at Two Bridges, N.J. Increase --

01382500 Pequannock River at Macopin Intake Dam, N.J. -- --

01387500 Ramapo River near Mahwah, N.J. -- --

01389500 Passaic River at Little Falls, N.J. Increase --

01391500 Saddle River at Lodi, N.J. Increase Increase

Raritan Water Region

01394500 Rahway River near Springfield, N.J. -- --

01395000 Rahway River at Rahway, N.J. -- --

01396660 Mulhockaway Creek at Van Syckel, N.J. -- Increase

01399780 Lamington River at Burnt Mills, N.J. -- --

01402000 Millstone River at Blackwells Mills, N.J. Increase --

01405340 Manalapan Brook at Federal Road near Manalapan, N.J. -- Increase

Atlantic Coastal Water Region

01408000 Manasquan River at Squankum, N.J. -- --

01408500 Toms River near Toms River, N.J. Increase Increase

01409416 Hammonton Creek at Wescoatville, N.J. -- Increase

01411110 Great Egg Harbor River at Weymouth, N.J. -- Increase

Upper Delaware Water Region

01367770 Wallkill River near Sussex, N.J. -- Decrease

01438500 Delaware River at Montague, N.J. -- --

01443000 Delaware River at Portland, Pa. -- --

01443500 Paulins Kill at Blairstown, N.J. -- --

01457400 Musconetcong River at Riegelsville, N.J. -- Increase

01457500 Delaware River at Riegelsville, N.J. -- --

01461000 Delaware River at Lumberville, Pa. -- --

01463500 Delaware River at Trenton, N.J. -- --

Lower Delaware Water Region

01411500 Maurice River at Norma, N.J. -- Increase

01412800 Cohansey River at Seeley, N.J. Increase Increase

01464515 Doctors Creek at Allentown, N.J. -- --

01467150 Cooper River at Haddonfield, N.J. Decrease Increase

01477120 Raccoon Creek near Swedesboro, N.J. -- --
Trends in the Quality of Water in New Jersey Streams 37

Table 22. Results of trend tests on flow-adjusted values of six water-quality characteristics at water-quality stations on New Jersey streams, water years 1998–2007.—Continued[--, no trend in flow-adjusted values of the water-quality characteristic during the period of study was identified at a 0.05 level of significance; Decrease, values of the water-quality characteristic decreased during the period of study; Increase, values of the water-quality characteristic increased during the period of study; n.d., not determined]

Station 

number Station name

Results of trend tests on flow-adjusted values of water-quality characteristics 

(water-quality measurements are year-round unless otherwise indicated)

Dissolved oxygen

pH

Total 

dissolved 

solids

Total 

phosphorus

Total organic 

nitrogen 

plus 

ammonia

Dissolved 

nitrate 

plus 

nitrite

Year 

round

Growing 

season 

(April–

September)

Passaic Water Region

01377000 Hackensack River at Rivervale, N.J. -- -- -- -- -- -- --01378560 Coles Brook at Hackensack, N.J. -- -- n.d. -- -- -- --01378780 Primrose Brook at Morristown National Historical Park, N.J. -- -- n.d. -- -- -- --01379200 Dead River near Millington, N.J. -- -- n.d. Increase Decrease -- Decrease01380100 Beaver Brook at Rockaway, N.J. -- -- n.d. -- -- -- Increase01381800 Whippany River near Pine Brook, N.J. -- -- -- Increase Decrease -- --01382000 Passaic River at Two Bridges, N.J. -- Decrease n.d. -- Decrease -- --01382500 Pequannock River at Macopin Intake Dam, N.J. -- -- -- -- -- Increase --01387500 Ramapo River near Mahwah, N.J. -- -- -- -- -- -- --01388500 Pompton River at Pompton Plains, N.J. Decrease n.d. -- -- -- -- Increase01389500 Passaic River at Little Falls, N.J. -- -- n.d. -- -- Decrease --01391500 Saddle River at Lodi, N.J. -- -- -- Increase -- Decrease Increase

Raritan Water Region

01394500 Rahway River near Springfield, N.J. n.d. n.d. Increase Increase -- -- --01395000 Rahway River at Rahway, N.J. -- -- -- Increase -- -- --01396660 Mulhockaway Creek at Van Syckel, N.J. -- -- -- -- -- -- Increase01398000 Neshanic River at Reaville, N.J. -- -- -- -- -- -- --01398102 South Branch Raritan River at South Branch, N.J. -- -- n.d. Increase -- -- --01399780 Lamington River at Burnt Mills, N.J. -- -- n.d. Increase -- -- --01400000 North Branch Raritan River near Raritan, N.J. n.d. -- -- Increase -- -- Increase01400640 Millstone River near Grovers Mill, N.J. -- -- n.d. -- Decrease -- --01401400 Heathcote Brook at Kingston, N.J. -- -- n.d. Increase -- -- --01402000 Millstone River at Blackwells Mills, N.J. -- -- -- -- -- -- --01403385 Bound Brook at Route 28 at Middlesex, N.J. -- -- n.d. -- Decrease -- --01405340 Manalapan Brook at Federal Road near Manalapan, N.J. -- -- n.d. Increase -- -- Increase
38 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007 Table 22. Results of trend tests on flow-adjusted values of six water-quality characteristics at water-quality stations on New Jersey streams, water years 1998–2007.—Continued [--, no trend in flow-adjusted values of the water-quality characteristic during the period of study was identified at a 0.05 level of significance; Decrease, values of the water-quality characteristic decreased dur- ing the period of study; Increase, values of the water-quality characteristic increased during the period of study; n.d., not determined] Station number Station name Results of trend tests on flow-adjusted values of water-quality characteristics (water-quality measurements are year-round unless otherwise indicated) Dissolved oxygen pH Total dissolved solids Total phosphorus Total organic nitrogen plus ammonia Dissolved nitrate plus nitrite Year round Growing season (April– September) Atlantic Coastal Water Region 01408000 Manasquan River at Squankum, N.J. -- -- Decrease Increase -- Increase -- 01408009 Mingamahone Brook near Earle, N.J. -- -- n.d. -- Increase Increase -- 01408100 North Branch Metedeconk River at Lakewood, N.J. -- -- n.d. Increase -- -- Increase 01408500 Toms River near Toms River, N.J. -- Decrease Increase Increase Decrease -- Increase 01408830 Cedar Creek at Cedar Crest, N.J. -- Increase n.d. -- -- -- n.d. 01409387 Mullica River at outlet of Atsion Lake at Atsion, N.J. -- -- n.d. -- -- -- -- 0140940950 Blue Anchor Brook at Elm, N.J. -- -- n.d. Increase -- -- -- 01409416 Hammonton Creek at Wescoatville, N.J. -- -- n.d. Increase -- -- Increase 01409500 Batsto River at Batsto, N.J. -- Increase n.d. -- -- -- Increase 01409815 West Branch Wading River at Maxwell, N.J. -- -- n.d. -- Increase -- n.d. 01410150 East Branch Bass River near New Gretna, N.J. -- Increase -- Increase -- -- n.d. 01411035 Hospitality Branch at Blue Bell Road near Cecil, N.J. -- -- n.d. -- -- -- Decrease 01411110 Great Egg Harbor River at Weymouth, N.J. -- -- n.d. Increase -- Increase Increase

01411196 Babcock Creek near Mays Landing, N.J. -- -- n.d. -- -- -- Increase

01411400 Fishing Creek at Rio Grande, N.J. -- -- n.d. -- Increase -- --01411444 West Creek near Leesburg, N.J. -- -- n.d. -- -- -- --

Upper Delaware Water Region

01367625 Wallkill River at Sparta, N.J. -- -- n.d. -- Increase -- --01367770 Wallkill River near Sussex, N.J. -- n.d. n.d. -- -- -- Decrease01367800 Papakating Creek at Pellettown, N.J. -- -- -- -- -- Decrease --01368820 Double Kill at Wawayanda, N.J. -- -- n.d. -- -- -- --01438500 Delaware River at Montague, N.J. Decrease -- Decrease -- Decrease -- --01440000 Flat Brook near Flatbrookville, N.J. n.d. n.d. -- -- -- -- --01442760 Dunnfield Creek at Dunnfield, N.J. -- -- n.d. -- -- n.d. --01443000 Delaware River at Portland, Pa. -- -- n.d. -- -- Increase --
Trends in the Quality of Water in New Jersey Streams 39

Table 22. Results of trend tests on flow-adjusted values of six water-quality characteristics at water-quality stations on New Jersey streams, water years 1998–2007.—Continued[--, no trend in flow-adjusted values of the water-quality characteristic during the period of study was identified at a 0.05 level of significance; Decrease, values of the water-quality characteristic decreased during the period of study; Increase, values of the water-quality characteristic increased during the period of study; n.d., not determined]

Station 

number Station name

Results of trend tests on flow-adjusted values of water-quality characteristics 

(water-quality measurements are year-round unless otherwise indicated)

Dissolved oxygen

pH

Total 

dissolved 

solids

Total 

phosphorus

Total organic 

nitrogen 

plus 

ammonia

Dissolved 

nitrate 

plus 

nitrite

Year 

round

Growing 

season 

(April–

September)

Upper Delaware Water Region

01443500 Paulins Kill at Blairstown, N.J. -- -- -- -- -- Decrease --01446400 Pequest River at Belvidere, N.J. -- Increase n.d. -- -- -- --01457400 Musconetcong River at Riegelsville, N.J. -- -- n.d. -- Decrease Decrease Increase01457500 Delaware River at Riegelsville, N.J. Decrease Decrease -- -- Decrease -- --01458570 Nishisakawick Creek near Frenchtown, N.J. -- -- n.d. -- -- -- --01461000 Delaware River at Lumberville, Pa. -- -- Increase -- Decrease -- --01463500 Delaware River at Trenton, N.J. -- -- -- -- Decrease -- --01463850 Miry Run at Route 533 at Mercerville, N.J. -- n.d. n.d. Increase -- -- --01464020 Assunpink Creek at Peace Street at Trenton, N.J. -- -- n.d. Increase Decrease Decrease --

Lower Delaware Water Region

01411466 Indian Branch near Malaga, N.J. -- -- n.d. -- -- -- Increase01411500 Maurice River at Norma, N.J. n.d. -- -- -- -- Increase Increase01411955 Gravelly Run at Laurel Lake, N.J. -- -- n.d. -- -- -- --

01412800 Cohansey River at Seeley, N.J. -- -- n.d. -- -- -- Increase01464504 Crosswicks Creek at Groveville Road at Groveville, N.J. -- -- n.d. Increase -- -- Increase01464515 Doctors Creek at Allentown, N.J. -- -- n.d. -- -- -- --01465893 Little Creek at Chairville, N.J. -- -- n.d. -- -- Increase --01466500 McDonalds Branch in Byrne State Forest, N.J. -- Decrease -- -- n.d. -- n.d.01467005 North Branch Rancocas Creek at Iron Works Park at Mount Holly, N.J. -- -- n.d. -- Increase Increase Decrease01467150 Cooper River at Haddonfield, N.J. Decrease -- n.d. Increase -- Increase Increase01467359 North Branch Big Timber Creek at Glendora, N.J. -- -- n.d. Increase -- -- Increase01477120 Raccoon Creek near Swedesboro, N.J. -- -- -- Increase -- -- --01482500 Salem River at Woodstown, N.J. -- -- -- Increase -- -- --
40 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Summary and Conclusions

Trends in flow-adjusted values of selected water-quality 

characteristics measured year-round during water years 1998–

2007 were determined for 70 stations on New Jersey streams. 

Water-quality characteristics included in the analysis are 

dissolved oxygen, pH, total dissolved solids, total phosphorus, 

total organic nitrogen plus ammonia, and dissolved nitrate 

plus nitrite. Trend tests also were conducted on measurements 

of dissolved oxygen made only during the growing season, 

April–September. Nearly all of the water-quality data analyzed 

were collected by the NJDEP and the USGS as part of the 

New Jersey Department of Environmental Protection Ambient 

Surface-Water Quality Monitoring Network.

Monotonic trends in flow-adjusted values of water quality were determined by use of procedures of the ESTREND 

computer program. A 0.05 level of significance was selected to 

indicate a trend.

Trends in dissolved oxygen were identified with the 

Seasonal Kendall test. Tests of year-round values are reported 

for 66 stations; decreases and increases in concentration were 

identified at 4 and 0 stations, respectively. Tests of growingseason values are reported for 65 stations; decreases and 

increases in concentration were identified at 4 and 4 stations, 

respectively. Results of tests of year-round measurements and 

growing-season measurements are not reported for four and 

five stations, respectively, because these results were clearly 

affected by a trend in time of measurement.

Trends in pH were identified with the Seasonal Kendall 

test. Results are presented for 26 stations; decreasing and 

increasing values were identified at 2 and 3 stations, respectively. Results are not presented for ASWQMN stations sampled by the USGS because an examination of the pH values 

measured by the USGS indicated that they were affected by a 

change in field methods during the period of study. Results at 

one station are not presented because they were affected by a 

trend in time of measurement.

Trends in total dissolved solids were identified with the 

Seasonal Kendall test. Results are presented for 70 stations; 

decreases and increases in concentration were identified at 0 

and 24 stations, respectively.

Trends in total phosphorus, total organic nitrogen plus 

ammonia, and dissolved nitrate plus nitrite were identified by 

use of Tobit regression. Tests were conducted on all measurements at each station and were repeated without the most 

extreme outlying point. The results presented are those from 

tests conducted on all measurements if the results of the two 

tests were equivalent. Otherwise, the results presented are 

those of the tests without the single outlier.

Results of tests of total phosphorus are presented for 

69 stations. Decreases and increases in concentration were 

identified at 12 and 5 stations, respectively. Of the five stations 

on the Delaware River included in this study, decreases in 

concentration were identified at four.

Results of tests of total organic nitrogen plus ammonia 

are presented for 69 stations. Decreases and increases in concentration during the period of study were identified at six and 

nine stations, respectively.

Results of tests of dissolved nitrate plus nitrite are presented for 66 stations. Decreases and increases in concentration were identified at 4 and 19 stations, respectively.

Results of this study are compared with results of two 

previous studies of trends in the water quality of streams 

throughout New Jersey—one for water years 1980–86 and one 

for water years 1986‐95. For example, the fractions of stations 

with trends in total dissolved solids or sum of dissolved solids 

were compared. Trends of increasing concentrations were 

identified at 24 percent of the stations analyzed during water 

years 1980–86, 26 percent of the stations analyzed during 

water years 1986–95, and 34 percent of stations analyzed during water years 1998–2007.

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42 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Table 4. Summary statistics for dissolved oxygen at water-quality stations on New Jersey streams, water years 

1998–2007.—Continued

[n.a., not applicable]

Station 

number

Results of 

trend tests 

presented

Number of 

measurements

Nondetect measurements Statistic, in milligrams per liter

Number

Percent 

of all 

measurements

Maximum 

reporting 

level, in 

milligrams 

per liter Minimum

25th 

percentile Median

75th 

percentile Maximum

Passaic Water Region

01377000 Yes 39 0 0 n.a. 3.7 6.6 7.7 9.5 14.3

01378560 Yes 39 0 0 n.a. 4.1 6.4 7.3 10.2 15.6

01378780 Yes 39 0 0 n.a. 8.3 9.4 10.7 12.2 14.6

01379200 Yes 39 0 0 n.a. 3.6 6.6 7.8 10.7 13.2

01380100 Yes 40 0 0 n.a. 6.6 7.5 8.9 11.4 14.1

01381800 Yes 40 0 0 n.a. 1.8 6.9 7.8 10.0 13.2

01382000 Yes 39 0 0 n.a. 4.2 5.9 8.6 11.2 16.0

01382500 Yes 40 0 0 n.a. 6.9 8.2 10.4 13.3 15.0

01387500 Yes 40 0 0 n.a. 5.8 7.4 8.8 11.9 15.2

01388500 Yes 40 0 0 n.a. 6.5 8.4 9.7 12.2 14.7

01389500 Yes 38 0 0 n.a. 5.6 8.1 9.3 12.5 14.6

01391500 Yes 40 0 0 n.a. 4.5 6.1 7.8 9.1 13.3

Raritan Water Region

01394500 No 40 0 0 n.a. 3.3 5.6 6.7 9.6 14.9

01395000 Yes 40 0 0 n.a. 3.5 6.5 7.6 10.7 13.3

01396660 Yes 40 0 0 n.a. 8.3 9.4 11.0 12.9 14.4

01398000 Yes 39 0 0 n.a. 4.8 7.9 10.6 12.9 17.2

01398102 Yes 40 0 0 n.a. 5.9 8.5 10.4 12.5 15.8

01399780 Yes 39 0 0 n.a. 7.3 9.4 12.8 14.1 17.3

01400000 No 39 0 0 n.a. 6.6 8.7 10.4 13.1 14.6

01400640 Yes 36 0 0 n.a. 5.5 7.6 9.3 11.7 13.5

01401400 Yes 40 0 0 n.a. 6.8 8.0 8.7 11.6 14.3

01402000 Yes 40 0 0 n.a. 2.9 5.7 7.6 11.0 13.0

01403385 Yes 40 0 0 n.a. 3.8 5.3 7.2 11.0 14.9

01405340 Yes 40 0 0 n.a. 7.4 8.5 9.8 12.4 14.4

Atlantic Coastal Water Region

01408000 Yes 40 0 0 n.a. 7.0 8.2 9.4 10.5 12.3

01408009 Yes 40 0 0 n.a. 6.6 7.9 8.6 9.6 12.5

01408100 Yes 40 0 0 n.a. 5.0 7.5 9.1 11.6 13.8

01408500 Yes 40 0 0 n.a. 6.3 7.7 8.6 11.2 13.5

01408830 Yes 40 0 0 n.a. 7.6 8.5 9.8 11.8 13.3

01409387 Yes 40 0 0 n.a. 6.0 7.6 9.4 11.9 13.0

0140940950 Yes 40 0 0 n.a. 4.3 8.0 9.4 11.8 15.3

01409416 Yes 39 0 0 n.a. 5.8 7.2 8.1 10.4 12.2

01409500 Yes 37 0 0 n.a. 6.4 7.9 9.2 10.8 13.4

01409815 Yes 39 0 0 n.a. 6.4 8.0 8.9 11.2 12.9

01410150 Yes 40 0 0 n.a. 5.5 6.5 7.8 9.6 11.6
Table 4 43

Table 4. Summary statistics for dissolved oxygen at water-quality stations on New Jersey streams, water years 

1998–2007.—Continued

[n.a., not applicable]

Station 

number

Results of 

trend tests 

presented

Number of 

measurements

Nondetect measurements Statistic, in milligrams per liter

Number

Percent 

of all 

measurements

Maximum 

reporting 

level, in 

milligrams 

per liter Minimum

25th 

percentile Median

75th 

percentile Maximum

Atlantic Coastal Water Region

01411035 Yes 40 0 0 n.a. 5.2 7.4 8.2 10.5 12.5

01411110 Yes 40 0 0 n.a. 7.3 8.2 9.0 11.4 13.2

01411196 Yes 40 0 0 n.a. 6.1 7.5 8.2 10.0 12.0

01411400 Yes 40 0 0 n.a. 2.9 5.3 8.0 9.6 12.6

01411444 Yes 35 0 0 n.a. 2.8 6.5 8.8 10.4 12.2

Upper Delaware Water Region

01367625 Yes 39 0 0 n.a. 7.3 8.7 10.6 12.3 14.8

01367770 Yes 39 0 0 n.a. 6.1 7.5 8.7 12.1 14.8

01367800 Yes 34 0 0 n.a. 8.0 9.3 10.7 13.2 14.4

01368820 Yes 38 0 0 n.a. 3.6 7.3 9.7 12.3 14.3

01438500 Yes 40 0 0 n.a. 6.9 8.5 9.9 12.0 14.3

01440000 No 40 0 0 n.a. 6.2 9.3 10.9 12.7 15.2

01442760 Yes 39 0 0 n.a. 8.5 9.7 11.3 12.6 14.9

01443000 Yes 39 0 0 n.a. 7.4 8.3 11.1 13.7 15.8

01443500 Yes 40 0 0 n.a. 6.2 8.7 10.5 13.1 16.2

01446400 Yes 40 0 0 n.a. 8.6 10.0 11.2 13.5 17.3

01457400 Yes 40 0 0 n.a. 8.3 9.5 11.0 13.4 15.5

01457500 Yes 40 0 0 n.a. 6.6 8.4 10.4 11.7 14.0

01458570 Yes 40 0 0 n.a. 5.7 9.1 11.8 13.8 16.5

01461000 Yes 39 0 0 n.a. 6.7 8.1 9.7 12.2 15.2

01463500 Yes 36 0 0 n.a. 7.6 9.0 10.6 13.2 16.2

01463850 Yes 40 0 0 n.a. 1.2 5.0 7.3 10.6 12.9

01464020 Yes 40 0 0 n.a. 7.0 8.1 9.5 11.8 13.5

Lower Delaware Water Region

01411466 Yes 38 0 0 n.a. 3.8 6.1 7.5 9.4 12.2

01411500 No 36 0 0 n.a. 5.8 7.1 8.3 10.4 12.8

01411955 Yes 40 0 0 n.a. 5.6 7.6 8.8 10.2 12.6

01412800 Yes 38 0 0 n.a. 6.4 7.8 9.2 10.8 14.1

01464504 Yes 39 0 0 n.a. 6.7 7.9 9.3 11.7 14.8

01464515 Yes 40 0 0 n.a. 1.9 6.1 8.9 11.9 14.3

01465893 Yes 38 0 0 n.a. 5.8 7.3 8.7 11.2 12.9

01466500 Yes 40 0 0 n.a. 2.0 2.7 3.4 6.2 9.4

01467005 Yes 39 0 0 n.a. 6.4 8.4 9.9 12.1 14.2

01467150 Yes 39 0 0 n.a. 4.6 6.8 7.9 10.5 12.7

01467359 Yes 40 0 0 n.a. 3.5 5.9 8.2 11.2 13.6

01477120 Yes 40 0 0 n.a. 5.3 7.6 8.8 11.4 13.2

01482500 Yes 40 0 0 n.a. 5.2 8.0 9.5 11.8 15.8
44 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007 Table 5a. Results of trend tests on year-round flow-adjusted concentrations of dissolved oxygen at water-quality stations on New Jersey streams, water years 1998–2007.—Continued [--, no trend in flow-adjusted concentrations of dissolved oxygen during the period of study was identified at a 0.05 level of significance; Decrease, dissolved oxygen decreased during the period of study; n.d., not determined; results of trend tests of flow-adjusted concentrations of dissolved oxygen are not presented if concentration of dissolved oxygen correlated with time of measurement and if there was a trend in time of measurement; -- (c), no correlation at the 0.05 level of significance was identified between concentration of dissolved oxygen and time of measurement; Increase (c), dissolved oxygen increased with increasing time of measurement; -- (t), no trend in time of measurement during the period of study was identified at a 0.05 level of significance; Decrease (t), time of measurement decreased during the period of study; Increase (t), time of measurement increased during period of study; +, trend slope indicates that the time of measurement tended to increase during the period of study; -, trend slope indicates that the time of measurement tended to decrease during the period of study] Station number Results of Seasonal Kendall trend tests of flow-adjusted concentrations of dissolved oxygen Results of tests to assess the effects of trends in times of measurement on the results of trend tests of flow-adjusted concentrations of dissolved oxygen Summary result Trend slope Kendall tau tests for correlation of dissolved oxygen and time of measurement Seasonal Kendall trend tests of time of measurement of dissolved oxygen Level of significance In milligrams per liter per year In percent of median value per year (median value in milligrams per liter) Summary result Level of significance Summary result Trend slope Level of significance Direction Passaic Water Region 01377000 -- 0.070 -0.156 -2.0 (7.7) -- (c) 0.062 -- (t) 0.058 - 01378560 -- 0.287 -0.059 -0.8 (7.4) -- (c) 0.390 -- (t) 1.000 n.d. 01378780 -- 0.364 0.036 0.3 (10.8) -- (c) 0.120 -- (t) 0.552 - 01379200 -- 0.931 0.010 0.1 (7.8) -- (c) 0.065 -- (t) 0.622

+

01380100 -- 0.505 -0.051 -0.6 (8.9) -- (c) 0.953 -- (t) 0.843

+

01381800 -- 0.610 -0.025 -0.3 (7.9) -- (c) 0.762 -- (t) 0.849 n.d.01382000 -- 0.824 -0.078 -0.9 (8.6) -- (c) 0.163 -- (t) 0.806

+

01382500 -- 0.355 -0.118 -1.1 (10.6) -- (c) 0.887 -- (t) 0.184 n.d.01387500 -- 0.364 0.095 1.1 (9) -- (c) 0.081 -- (t) 0.834 n.d.01388500 Decrease 0.042 -0.130 -1.3 (9.7) -- (c) 0.236 Decrease (t) 0.025 -01389500 -- 0.679 -0.038 -0.4 (9.3) -- (c) 0.228 -- (t) 0.285 -01391500 -- 0.390 0.049 0.6 (7.9) -- (c) 0.111 -- (t) 0.599

+

Raritan Water Region

01394500 n.d. n.d. n.d. n.d. (n.d.) Increase (c) 0.035 Decrease (t) 0.008 -01395000 -- 0.053 -0.160 -2.0 (7.9) Increase (c) 0.007 -- (t) 0.661 -01396660 -- 0.376 -0.028 -0.3 (11.1) -- (c) 0.254 -- (t) 0.309 n.d.01398000 -- 0.111 -0.181 -1.7 (10.8) -- (c) 0.156 Decrease (t) 0.038 -01398102 -- 0.148 -0.166 -1.6 (10.4) -- (c) 0.870 -- (t) 0.866

+

01399780 -- 0.567 0.076 0.6 (12.8) Increase (c) 0.003 -- (t) 0.450 -01400000 n.d. n.d. n.d. n.d. (n.d.) Increase (c) 0.010 Decrease (t) 0.026 -01400640 -- 0.520 -0.032 -0.3 (9.3) -- (c) 0.293 -- (t) 0.234

+

01401400 -- 0.128 0.097 1.1 (8.8) Increase (c) 0.028 -- (t) 0.553 -01402000 -- 0.068 -0.176 -2.3 (7.7) -- (c) 0.160 Decrease (t) 0.002 -01403385 -- 0.679 -0.036 -0.5 (7.3) -- (c) 0.207 -- (t) 0.670 -01405340 -- 0.790 0.034 0.3 (9.9) -- (c) 0.216 -- (t) 0.106 -
Table 5 45

Table 5a. Results of trend tests on year-round flow-adjusted concentrations of dissolved oxygen at water-quality stations on New Jersey streams, water years 1998–2007.—Continued [--, no trend in flow-adjusted concentrations of dissolved oxygen during the period of study was identified at a 0.05 level of significance; Decrease, dissolved oxygen decreased during the period of study; n.d., not determined; results of trend tests of flow-adjusted concentrations of dissolved oxygen are not presented if concentration of dissolved oxygen correlated with time of measurement and if there was a trend in time of measurement; -- (c), no correlation at the 0.05 level of significance was identified between concentration of dissolved oxygen and time of measurement; Increase (c), dissolved oxygen increased with increasing time of measurement; -- (t), no trend in time of measurement during the period of study was identified at a 0.05 level of significance; Decrease (t), time of measurement decreased during the period of study; Increase (t), time of measurement increased during period of study; +, trend slope indicates that the time of measurement tended to increase during the period of study; -, trend slope indicates that the time of measurement tended to decrease during the period of study] 

Station 

number

Results of Seasonal Kendall trend tests of flow-adjusted concentrations 

of dissolved oxygen

Results of tests to assess the effects of trends in times of measurement on the 

results of trend tests of flow-adjusted concentrations of dissolved oxygen

Summary 

result

Trend slope

Kendall tau tests for correlation of 

dissolved oxygen and time 

of measurement

Seasonal Kendall trend tests of time 

of measurement of dissolved oxygen

Level of 

significance 

In milligrams per 

liter per year

In percent of median value 

per year (median value in 

milligrams per liter)

Summary 

result

Level of 

significance

Summary 

result

Trend slope

Level of 

significance Direction 

Atlantic Coastal Water Region

01408000 -- 0.295 -0.083 -0.9 (9.5) -- (c) 0.077 Decrease (t) 0.002 -01408009 -- 0.901 0.015 0.2 (8.6) -- (c) 0.752 -- (t) 0.489 -01408100 -- 0.694 0.026 0.3 (9.1) -- (c) 0.138 -- (t) 0.091 +01408500 -- 0.067 -0.099 -1.1 (8.6) -- (c) 0.677 -- (t) 0.062 -01408830 -- 0.913 -0.001 0.0 (9.9) -- (c) 0.123 -- (t) 0.773 +01409387 -- 0.501 -0.046 -0.5 (9.6) -- (c) 0.362 -- (t) 0.055 -

0140940950 -- 0.294 -0.058 -0.6 (9.6) -- (c) 0.115 -- (t) 0.676 -

01409416 -- 0.668 -0.019 -0.2 (8.1) -- (c) 0.080 Decrease (t) 0.039 -01409500 -- 1.000 -0.002 0.0 (9.2) -- (c) 0.740 -- (t) 0.185 -01409815 -- 0.369 -0.040 -0.5 (8.9) -- (c) 0.601 -- (t) 0.464 -01410150 -- 0.126 0.092 1.2 (7.9) -- (c) 0.981 Decrease (t) 0.043 -

01411035 -- 0.810 -0.021 -0.2 (8.5) -- (c) 0.252 Decrease (t) 0.040 -

01411110 -- 0.831 -0.013 -0.1 (9.1) -- (c) 0.119 -- (t) 0.838 n.d.

01411196 -- 0.680 0.032 0.4 (8.3) -- (c) 0.779 -- (t) 1.000 n.d.

01411400 -- 0.883 -0.038 -0.5 (8) -- (c) 0.349 Increase (t) 0.029 +01411444 -- 0.960 0.004 0.0 (8.9) -- (c) 0.989 -- (t) 0.198 -

Upper Delaware Water Region

01367625 -- 0.710 0.032 0.3 (10.6) -- (c) 0.932 -- (t) 0.099 -01367770 -- 0.173 0.101 1.2 (8.7) -- (c) 0.060 -- (t) 0.060 +01367800 -- 0.087 -0.256 -2.3 (10.9) Increase (c) 0.031 -- (t) 0.153 -01368820 -- 0.886 0.028 0.3 (10) -- (c) 0.241 Increase (t) 0.038 +01438500 Decrease 0.050 -0.140 -1.4 (10) -- (c) 0.355 -- (t) 0.181 -01440000 n.d. n.d. n.d. n.d. (n.d.) Increase (c) 0.000 Decrease (t) 0.001 -01442760 -- 0.077 -0.113 -1.0 (11.3) -- (c) 0.593 -- (t) 0.516 +01443000 -- 0.053 -0.031 -0.3 (11.1) -- (c) 0.127 -- (t) 0.673 -
46 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007 Table 5a. Results of trend tests on year-round flow-adjusted concentrations of dissolved oxygen at water-quality stations on New Jersey streams, water years 1998–2007.—Continued [--, no trend in flow-adjusted concentrations of dissolved oxygen during the period of study was identified at a 0.05 level of significance; Decrease, dissolved oxygen decreased during the period of study; n.d., not determined; results of trend tests of flow-adjusted concentrations of dissolved oxygen are not presented if concentration of dissolved oxygen correlated with time of measurement and if there was a trend in time of measurement; -- (c), no correlation at the 0.05 level of significance was identified between concentration of dissolved oxygen and time of measurement; Increase (c), dissolved oxygen increased with increasing time of measurement; -- (t), no trend in time of measurement during the period of study was identified at a 0.05 level of significance; Decrease (t), time of measurement decreased during the period of study; Increase (t), time of measurement increased during period of study; +, trend slope indicates that the time of measurement tended to increase during the period of study; -, trend slope indicates that the time of measurement tended to decrease during the period of study] Station number Results of Seasonal Kendall trend tests of flow-adjusted concentrations of dissolved oxygen Results of tests to assess the effects of trends in times of measurement on the results of trend tests of flow-adjusted concentrations of dissolved oxygen Summary result Trend slope Kendall tau tests for correlation of dissolved oxygen and time of measurement Seasonal Kendall trend tests of time of measurement of dissolved oxygen Level of significance In milligrams per liter per year In percent of median value per year (median value in milligrams per liter) Summary result Level of significance Summary result Trend slope Level of significance Direction Upper Delaware Water Region 01443500 -- 0.308 -0.115 -1.1 (10.7) Increase (c) 0.029 -- (t) 0.197 - 01446400 -- 0.053 0.108 1.0 (11.2) Increase (c) 0.011 -- (t) 0.288

+

01457400 -- 0.750 -0.014 -0.1 (11.1) -- (c) 0.861 -- (t) 0.125 -01457500 Decrease 0.005 -0.179 -1.7 (10.4) -- (c) 0.735 Decrease (t) 0.025 -01458570 -- 0.163 0.244 2.1 (11.8) -- (c) 0.529 -- (t) 0.245

+

01461000 -- 0.071 -0.085 -0.9 (9.8) -- (c) 0.850 -- (t) 0.058 -01463500 -- 0.886 -0.008 -0.1 (10.8) -- (c) 0.216 -- (t) 0.256 -01463850 -- 0.088 -0.208 -2.7 (7.6) -- (c) 0.665 Decrease (t) 0.011 -01464020 -- 0.496 0.049 0.5 (9.5) -- (c) 0.744 -- (t) 0.121

+

Lower Delaware Water Region

01411466 -- 0.743 0.020 0.3 (7.5) -- (c) 0.127 -- (t) 0.053 -01411500 n.d. n.d. n.d. n.d. (n.d.) Increase (c) 0.033 Decrease (t) 0.036 -01411955 -- 0.411 0.071 0.8 (8.9) Increase (c) 0.045 -- (t) 0.849

+

01412800 -- 0.739 -0.020 -0.2 (9.4) -- (c) 0.441 -- (t) 0.361 -01464504 -- 0.875 -0.017 -0.2 (9.3) -- (c) 0.594 -- (t) 0.091

+

01464515 -- 0.850 0.049 0.6 (8.9) -- (c) 0.086 -- (t) 0.235 -01465893 -- 0.514 -0.067 -0.8 (8.7) -- (c) 0.442 -- (t) 0.637

+

01466500 -- 0.076 -0.117 -3.5 (3.4) -- (c) 0.526 Decrease (t) 0.022 -01467005 -- 0.179 0.091 0.9 (10.2) -- (c) 0.716 -- (t) 0.198 -01467150 Decrease 0.039 -0.255 -3.2 (7.9) -- (c) 0.076 Decrease (t) 0.016 -01467359 -- 0.169 0.178 2.2 (8.3) -- (c) 0.762 -- (t) 0.881 -01477120 -- 0.688 0.041 0.5 (8.8) -- (c) 0.980 -- (t) 0.167 n.d.01482500 -- 0.693 -0.088 -0.9 (9.5) -- (c) 0.064 -- (t) 0.850 n.d.
Table 5 47

Table 5b. Results of trend tests on growing-season flow-adjusted concentrations of dissolved oxygen at water-quality stations on New Jersey streams, water years 1998–2007.—Continued[Growing season is April–September; --, no trend in flow-adjusted concentration of dissolved oxygen during the period of study was identified at a 0.05 level of significance; Decrease, dissolved oxygen decreased during the period of study; Increase, dissolved oxygen increased during the period of study; n.d., not determined; results of trend tests of flow-adjusted concentrations of dissolved oxygen are not presented if concentrations of dissolved oxygen correlated with time of measurement and if there was a trend in time of measurement; -- (c), no correlation at the 0.05 level of significance was identified between concentrations of dissolved oxygen and time of measurement; Decrease (c), dissolved oxygen decreased with increasing time of measurement; Increase (c), dissolved oxygen increased with increasing time of measurement; -- (t), no trend in time of measurement during the period of study was identified at a 0.05 level of significance; Decrease (t), time of measurement decreased during the period of study; Increase (t), time of measurement increased during the period of study; +, trend slope indicates that the time of measurement tended to increase during the period of study; -, trend slope indicates that the time of measurement tended to decrease during the period of study] 

Station 

number

Results of Seasonal Kendall trend tests of flow-adjusted concentrations 

of dissolved oxygen

Results of tests to assess the effects of trends in time of measurement on the 

results of trend tests of flow-adjusted concentrations of dissolved oxygen

Summary 

result

Trend slope

Kendall tau tests for correlation of 

dissolved oxygen and time 

of measurement

Seasonal Kendall trend tests of time 

of measurement of dissolved oxygen

Level of 

significance 

In milligrams per 

liter per year

In percent of median value 

per year (median value in 

milligrams per liter)

Summary result Level of significance Summary result Trend slope Level of significance Direction 

Passaic Water Region

01377000 -- 0.176 -0.137 -2.1 (6.7) -- (c) 0.163 Decrease (t) 0.049 -01378560 -- 0.313 -0.094 -1.5 (6.4) -- (c) 0.325 -- (t) 0.101 +01378780 -- 0.429 0.050 0.5 (9.5) -- (c) 0.482 -- (t) 0.082 -01379200 -- 0.260 -0.097 -1.5 (6.6) -- (c) 0.479 -- (t) 0.555 +01380100 -- 0.298 -0.055 -0.7 (7.6) -- (c) 0.311 -- (t) 0.350 +01381800 -- 0.544 -0.029 -0.4 (6.9) -- (c) 0.298 -- (t) 0.775 n.d.01382000 Decrease 0.010 -0.354 -5.8 (6.1) -- (c) 0.068 -- (t) 0.605 -01382500 -- 0.956 0.006 0.1 (8.3) -- (c) 0.170 -- (t) 0.158 n.d.01387500 -- 0.951 -0.007 -0.1 (7.5) -- (c) 0.618 -- (t) 0.843 n.d.01388500 n.d. n.d. n.d. n.d. (n.d.) Increase (c) 0.031 Decrease (t) 0.034 -01389500 -- 0.240 -0.093 -1.1 (8.2) Increase (c) 0.016 -- (t) 0.323 -01391500 -- 0.110 0.110 1.8 (6.1) Increase (c) 0.038 -- (t) 0.625 +

Raritan Water Region

01394500 n.d. n.d. n.d. n.d. (n.d.) Increase (c) 0.001 Decrease (t) 0.038 -01395000 -- 0.123 -0.085 -1.3 (6.5) Increase (c) 0.015 -- (t) 1.000 n.d.01396660 -- 0.949 -0.007 -0.1 (9.4) -- (c) 0.083 -- (t) 0.113 -01398000 -- 1.000 -0.005 -0.1 (7.9) -- (c) 0.738 -- (t) 0.118 -01398102 -- 0.107 -0.167 -1.9 (8.7) -- (c) 0.103 -- (t) 0.335 -01399780 -- 0.229 0.141 1.5 (9.6) Increase (c) 0.016 -- (t) 0.737 -01400000 -- 1.000 0.006 0.1 (8.7) Increase (c) 0.011 -- (t) 0.121 -01400640 -- 0.702 0.015 0.2 (7.7) Increase (c) 0.022 -- (t) 1.000 -01401400 -- 0.063 0.114 1.4 (8) -- (c) 0.081 -- (t) 0.425 +01402000 -- 0.087 -0.179 -3.1 (5.7) -- (c) 0.206 Decrease (t) 0.002 -01403385 -- 0.638 -0.033 -0.6 (5.3) -- (c) 0.794 -- (t) 0.280 -01405340 -- 0.544 -0.052 -0.6 (8.7) -- (c) 0.871 -- (t) 1.000 -
48 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007 Table 5b. Results of trend tests on growing-season flow-adjusted concentrations of dissolved oxygen at water-quality stations on New Jersey streams, water years 1998–2007.—Continued [Growing season is April–September; --, no trend in flow-adjusted concentration of dissolved oxygen during the period of study was identified at a 0.05 level of significance; Decrease, dissolved oxygen decreased during the period of study; Increase, dissolved oxygen increased during the period of study; n.d., not determined; results of trend tests of flow-adjusted concentrations of dissolved oxygen are not presented if concentrations of dissolved oxygen correlated with time of measurement and if there was a trend in time of measurement; -- (c), no correlation at the 0.05 level of significance was identified between concentrations of dissolved oxygen and time of measurement; Decrease (c), dissolved oxygen decreased with increasing time of measurement; Increase (c), dissolved oxygen increased with increas- ing time of measurement; -- (t), no trend in time of measurement during the period of study was identified at a 0.05 level of significance; Decrease (t), time of measurement decreased during the period of study; Increase (t), time of measurement increased during the period of study; +, trend slope indicates that the time of measurement tended to increase during the period of study; -, trend slope indicates that the time of measurement tended to decrease during the period of study] Station number Results of Seasonal Kendall trend tests of flow-adjusted concentrations of dissolved oxygen Results of tests to assess the effects of trends in time of measurement on the results of trend tests of flow-adjusted concentrations of dissolved oxygen Summary result Trend slope Kendall tau tests for correlation of dissolved oxygen and time of measurement Seasonal Kendall trend tests of time of measurement of dissolved oxygen Level of significance In milligrams per liter per year In percent of median value per year (median value in milligrams per liter) Summary result Level of significance Summary result Trend slope Level of significance Direction Atlantic Coastal Water Region 01408000 -- 0.461 -0.076 -0.9 (8.3) -- (c) 0.426 Decrease (t) 0.007 - 01408009 -- 0.730 0.011 0.1 (7.9) -- (c) 0.922 -- (t) 0.839 - 01408100 -- 0.282 0.108 1.4 (7.6) -- (c) 0.126 -- (t) 0.148

+

01408500 Decrease 0.018 -0.104 -1.3 (7.8) -- (c) 0.583 Decrease (t) 0.014 -01408830 Increase 0.020 0.085 1.0 (8.5) -- (c) 0.555 -- (t) 0.526

+

01409387 -- 0.854 -0.005 -0.1 (7.6) -- (c) 0.672 -- (t) 0.139 -

0140940950 -- 0.104 -0.072 -0.9 (8.1) -- (c) 0.474 -- (t) 0.517

+

01409416 -- 0.922 0.024 0.3 (7.2) -- (c) 0.083 -- (t) 0.267 -01409500 Increase 0.050 0.130 1.6 (7.9) -- (c) 0.587 -- (t) 0.434 -01409815 -- 0.302 0.020 0.3 (8) -- (c) 0.157 -- (t) 1.000 n.d.01410150 Increase 0.047 0.105 1.6 (6.7) -- (c) 0.946 Decrease (t) 0.021 -

01411035 -- 0.869 -0.027 -0.4 (7.6) Increase (c) 0.045 -- (t) 0.310 -

01411110 -- 0.509 -0.024 -0.3 (8.2) -- (c) 0.552 -- (t) 0.291 -

01411196 -- 0.447 0.040 0.5 (7.6) -- (c) 0.239 -- (t) 0.799

+

01411400 -- 0.432 0.117 2.1 (5.6) -- (c) 0.718 -- (t) 0.070

+

01411444 -- 0.199 -0.167 -2.5 (6.7) -- (c) 0.649 -- (t) 0.077 -

Upper Delaware Water Region

01367625 -- 0.076 0.123 1.4 (8.7) -- (c) 0.833 -- (t) 0.132 -01367770 n.d. n.d. n.d. n.d. (n.d.) Increase (c) 0.003 Increase (t) 0.014

+

01367800 -- 0.164 -0.128 -1.4 (9.3) -- (c) 0.651 Decrease (t) 0.039 -01368820 -- 0.115 0.166 2.3 (7.2) -- (c) 0.542 Increase (t) 0.021

+

01438500 -- 0.085 -0.111 -1.3 (8.5) -- (c) 0.359 -- (t) 0.160 -01440000 n.d. n.d. n.d. n.d. (n.d.) Increase (c) 0.000 Decrease (t) 0.002 -01442760 -- 0.123 -0.095 -1.0 (10) -- (c) 0.536 -- (t) 0.951

+
Table 5 49

Table 5b. Results of trend tests on growing-season flow-adjusted concentrations of dissolved oxygen at water-quality stations on New Jersey streams, water years 1998–2007.—Continued[Growing season is April–September; --, no trend in flow-adjusted concentration of dissolved oxygen during the period of study was identified at a 0.05 level of significance; Decrease, dissolved oxygen decreased during the period of study; Increase, dissolved oxygen increased during the period of study; n.d., not determined; results of trend tests of flow-adjusted concentrations of dissolved oxygen are not presented if concentrations of dissolved oxygen correlated with time of measurement and if there was a trend in time of measurement; -- (c), no correlation at the 0.05 level of significance was identified between concentrations of dissolved oxygen and time of measurement; Decrease (c), dissolved oxygen decreased with increasing time of measurement; Increase (c), dissolved oxygen increased with increasing time of measurement; -- (t), no trend in time of measurement during the period of study was identified at a 0.05 level of significance; Decrease (t), time of measurement decreased during the period of study; Increase (t), time of measurement increased during the period of study; +, trend slope indicates that the time of measurement tended to increase during the period of study; -, trend slope indicates that the time of measurement tended to decrease during the period of study] 

Station 

number

Results of Seasonal Kendall trend tests of flow-adjusted concentrations 

of dissolved oxygen

Results of tests to assess the effects of trends in time of measurement on the 

results of trend tests of flow-adjusted concentrations of dissolved oxygen

Summary 

result

Trend slope

Kendall tau tests for correlation of 

dissolved oxygen and time 

of measurement

Seasonal Kendall trend tests of time 

of measurement of dissolved oxygen

Level of 

significance 

In milligrams per 

liter per year

In percent of median value 

per year (median value in 

milligrams per liter)

Summary result Level of significance Summary result Trend slope Level of significance Direction 

Upper Delaware Water Region

01443000 -- 0.550 -0.053 -0.6 (8.3) Increase (c) 0.037 -- (t) 1.000 n.d.01443500 -- 0.700 0.082 0.9 (8.7) Increase (c) 0.022 -- (t) 0.648 n.d.01446400 Increase 0.037 0.115 1.1 (10.1) -- (c) 0.579 -- (t) 0.598 +01457400 -- 0.489 -0.026 -0.3 (9.8) -- (c) 0.672 -- (t) 0.196 -01457500 Decrease 0.003 -0.207 -2.4 (8.6) -- (c) 0.192 -- (t) 0.053 -01458570 -- 0.176 0.185 2.0 (9.3) -- (c) 0.379 -- (t) 0.289 +01461000 -- 0.185 -0.132 -1.6 (8.2) -- (c) 0.233 -- (t) 0.090 -01463500 -- 0.820 0.018 0.2 (9.2) -- (c) 0.499 -- (t) 0.779 n.d.01463850 n.d. n.d. n.d. n.d. (n.d.) Increase (c) 0.023 Decrease (t) 0.032 -01464020 -- 0.956 0.003 0.0 (8.2) -- (c) 0.648 -- (t) 1.000 n.d.

Lower Delaware Water Region

01411466 -- 0.330 -0.156 -2.6 (6) -- (c) 0.360 -- (t) 0.212 -01411500 -- 0.080 -0.182 -2.5 (7.4) Increase (c) 0.027 -- (t) 0.148 -01411955 -- 0.799 -0.017 -0.2 (7.7) Increase (c) 0.029 -- (t) 0.371 +

01412800 -- 0.875 -0.016 -0.2 (7.8) -- (c) 0.304 -- (t) 0.905 -01464504 -- 0.563 -0.039 -0.5 (7.9) Decrease (c) 0.003 -- (t) 0.654 +01464515 -- 0.374 0.046 0.7 (6.4) Decrease (c) 0.044 -- (t) 1.000 n.d.01465893 -- 0.802 -0.022 -0.3 (7.5) -- (c) 0.399 -- (t) 0.105 +01466500 Decrease 0.030 -0.100 -3.5 (2.8) -- (c) 0.099 -- (t) 0.164 -01467005 -- 0.803 -0.034 -0.4 (8.4) Increase (c) 0.003 -- (t) 0.618 -01467150 -- 0.182 -0.147 -2.2 (6.8) -- (c) 0.057 -- (t) 0.076 -01467359 -- 0.758 -0.030 -0.5 (6.1) -- (c) 0.345 -- (t) 0.403 -01477120 -- 0.773 0.044 0.6 (7.7) -- (c) 0.203 -- (t) 0.943 n.d.01482500 -- 0.766 0.025 0.3 (8) -- (c) 0.601 -- (t) 0.806 -
50 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Table 5c. Results of trend tests on flow-adjusted concentrations of year-round and growing-season dissolved oxygen at selected 

water-quality stations on New Jersey streams, water years 1998–2007.

[Stations included are those at which a trend was identified in either year-round or growing-season concentrations at a 0.05 level of significance; --, no trend 

in flow-adjusted concentrations of dissolved oxygen during the period of study was identified at a 0.05 level of significance; Decrease, concentrations of dissolved oxygen decreased during the period of study; Increase, concentrations of dissolved oxygen increased during the period of study; n.d., not determined] 

Station 

number Station name

Results of trend tests in flow-adjusted concentrations of dissolved oxygen

Year-round measurements Growing-season measurements 

(April–September)

Passaic Water Region

01382000 Passaic River at Two Bridges, N.J. -- Decrease

01388500 Pompton River at Pompton Plains, N.J. Decrease n.d.

Raritan Water Region

(none)

Atlantic Coastal Water Region

01408500 Toms River near Toms River, N.J. -- Decrease

01408830 Cedar Creek at Cedar Crest, N.J. -- Increase

01409500 Batsto River at Batsto, N.J. -- Increase

01410150 East Branch Bass River near New Gretna, N.J. -- Increase

Upper Delaware Water Region

01438500 Delaware River at Montague, N.J. Decrease --

01446400 Pequest River at Belvidere, N.J. -- Increase

01457500 Delaware River at Riegelsville, N.J. Decrease Decrease

Lower Delaware Water Region

01466500 McDonalds Branch in Byrne State Forest, N.J. -- Decrease

01467150 Cooper River at Haddonfield, N.J. Decrease --
Table 6 51

Table 6. Summary statistics for pH at water-quality stations on New Jersey streams, water years 1998–2007.—Continued

[n.a., not applicable]

Station 

number

Results 

of trend 

tests 

presented

Number of 

measurements

Nondetect measurements Statistic, in standard units

Number

Percentage 

of all 

measurements

Maximum 

reporting level, in 

standard units

Minimum 25th 

percentile Median 75th percentile Maximum

Passaic Water Region

01377000 Yes 40 0 0 n.a. 7.1 7.6 7.7 7.8 8.1

01378560 No 39 0 0 n.a. 6.7 7.3 7.5 7.7 8.5

01378780 No 39 0 0 n.a. 6.3 6.9 7.2 7.5 7.7

01379200 No 40 0 0 n.a. 6.2 7.0 7.3 7.5 8.4

01380100 No 39 0 0 n.a. 6.1 6.8 7.0 7.4 8.0

01381800 Yes 40 0 0 n.a. 6.9 7.3 7.4 7.6 8.1

01382000 No 40 0 0 n.a. 6.8 7.2 7.3 7.5 8.8

01382500 Yes 40 0 0 n.a. 7.3 7.5 7.6 7.6 8.0

01387500 Yes 40 0 0 n.a. 7.3 7.6 7.7 7.8 8.1

01388500 Yes 40 0 0 n.a. 7.3 7.5 7.6 7.8 8.8

01389500 No 40 0 0 n.a. 7.0 7.4 7.6 7.8 8.2

01391500 Yes 39 0 0 n.a. 7.2 7.5 7.7 7.8 8.2

Raritan Water Region

01394500 Yes 40 0 0 n.a. 7.2 7.5 7.6 7.7 8.1

01395000 Yes 40 0 0 n.a. 7.4 7.6 7.8 7.9 8.4

01396660 Yes 40 0 0 n.a. 7.4 7.7 7.8 7.9 8.3

01398000 Yes 38 0 0 n.a. 6.9 7.7 8.0 8.2 9.1

01398102 No 40 0 0 n.a. 6.8 7.5 7.6 8.1 9.3

01399780 No 39 0 0 n.a. 7.0 7.5 7.7 8.2 9.3

01400000 Yes 40 0 0 n.a. 7.4 7.6 7.8 7.9 8.3

01400640 No 33 0 0 n.a. 5.9 6.4 6.8 7.1 7.4

01401400 No 40 0 0 n.a. 6.1 6.5 6.8 7.0 8.5

01402000 Yes 39 0 0 n.a. 6.9 7.2 7.4 7.6 8.2

01403385 No 40 0 0 n.a. 6.6 7.2 7.4 7.6 7.9

01405340 No 39 0 0 n.a. 4.3 5.9 6.5 6.8 7.9

Atlantic Coastal Water Region

01408000 Yes 39 0 0 n.a. 6.5 6.9 7.2 7.4 7.7

01408009 No 39 0 0 n.a. 5.4 5.9 6.2 6.5 7.1

01408100 No 38 0 0 n.a. 4.2 6.2 6.4 6.6 7.2

01408500 Yes 40 0 0 n.a. 4.4 5.4 5.8 6.0 6.4

01408830 No 39 0 0 n.a. 3.3 4.3 4.6 4.9 5.6

01409387 No 40 0 0 n.a. 3.7 4.1 4.5 4.9 5.7

0140940950 No 40 0 0 n.a. 6.0 6.4 6.7 6.9 7.6

01409416 No 40 0 0 n.a. 5.1 5.8 6.2 6.5 7.2

01409500 No 37 0 0 n.a. 4.2 4.9 5.3 5.6 5.8

01409815 No 40 0 0 n.a. 3.6 4.0 4.2 4.4 4.7

01410150 Yes 40 0 0 n.a. 4.1 4.3 4.4 4.5 4.8

01411035 No 40 0 0 n.a. 4.2 5.5 5.8 6.1 6.5

01411110 No 39 0 0 n.a. 3.7 5.0 5.8 6.2 6.6

01411196 No 38 0 0 n.a. 3.1 4.0 4.5 4.9 5.8

01411400 No 38 0 0 n.a. 5.6 6.3 6.6 6.8 7.3

01411444 No 35 0 0 n.a. 3.2 3.9 4.0 4.3 4.6
52 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Table 6. Summary statistics for pH at water-quality stations on New Jersey streams, water years 1998–2007.—Continued

[n.a., not applicable]

Station 

number

Results 

of trend 

tests 

presented

Number of 

measurements

Nondetect measurements Statistic, in standard units

Number

Percentage 

of all 

measurements

Maximum 

reporting level, in 

standard units

Minimum 25th 

percentile Median 75th percentile Maximum

Upper Delaware Water Region

01367625 No 40 0 0 n.a. 7.0 7.9 8.1 8.2 8.4

01367770 No 38 0 0 n.a. 7.4 7.7 7.8 7.9 8.2

01367800 Yes 36 0 0 n.a. 6.4 7.6 7.8 7.9 8.2

01368820 No 37 0 0 n.a. 6.6 7.3 7.4 7.6 7.8

01438500 Yes 40 0 0 n.a. 6.7 7.2 7.3 7.4 8.1

01440000 Yes 40 0 0 n.a. 7.3 7.7 7.9 8.0 8.2

01442760 No 39 0 0 n.a. 5.5 6.2 6.6 6.8 7.6

01443000 No 37 0 0 n.a. 6.1 7.0 7.3 7.6 8.6

01443500 Yes 40 0 0 n.a. 7.6 8.1 8.2 8.2 8.4

01446400 No 40 0 0 n.a. 7.8 8.1 8.3 8.4 8.7

01457400 No 40 0 0 n.a. 7.1 7.9 8.1 8.2 8.5

01457500 Yes 40 0 0 n.a. 7.4 7.6 7.8 7.9 8.3

01458570 No 39 0 0 n.a. 6.6 7.5 7.7 8.0 8.9

01461000 Yes 36 0 0 n.a. 6.8 7.8 7.9 8.2 8.8

01463500 Yes 39 0 0 n.a. 6.9 7.5 7.8 8.2 9.1

01463850 No 40 0 0 n.a. 5.5 6.2 6.4 6.7 6.9

01464020 No 40 0 0 n.a. 6.1 7.0 7.1 7.4 7.8

Lower Delaware Water Region

01411466 No 39 0 0 n.a. 3.3 4.1 4.4 4.7 5.6

01411500 Yes 36 0 0 n.a. 5.2 6.2 6.4 6.6 7.0

01411955 No 40 0 0 n.a. 3.4 4.2 4.6 5.1 5.4

01412800 No 39 0 0 n.a. 5.6 6.4 6.6 6.9 7.1

01464504 No 38 0 0 n.a. 6.5 6.8 7.1 7.2 7.6

01464515 No 39 0 0 n.a. 6.2 6.8 6.9 7.1 7.3

01465893 No 39 0 0 n.a. 3.5 4.0 4.3 4.8 6.6

01466500 Yes 40 0 0 n.a. 3.9 4.1 4.2 4.3 4.5

01467005 No 39 0 0 n.a. 5.0 5.9 6.4 6.6 7.5

01467150 No 40 0 0 n.a. 6.5 7.0 7.1 7.4 8.4

01467359 No 40 0 0 n.a. 6.2 6.6 6.8 7.0 7.5

01477120 Yes 40 0 0 n.a. 6.5 7.0 7.2 7.3 7.7

01482500 Yes 39 0 0 n.a. 6.4 7.0 7.4 7.6 9.3
Table 7 53

Table 7. Results of trend tests on flow-adjusted values of pH at water-quality stations on New Jersey streams, water years 1998–2007.—Continued[--, no trend in flow-adjusted values of pH during the period of study was identified at a 0.05 level of significance; Decrease, pH decreased during the period of study; Increase, pH increased during the period of study; n.d., not determined; results of trend tests of flow-adjusted values of pH are not presented if (a) pH values were affected by a change in field methods or (b) pH correlated with time of measurement and there was a trend in time of measurement; -- (c), no correlation at the 0.05 level of significance was identified between values of pH and time of measurement; Decrease (c), pH decreased with increasing time of measurement; -- (t), no trend in time of measurement during the period of study was identified at a 0.05 level of significance; Decrease (t), time of measurement decreased during the period of study; +, trend slope indicates that the time of measurement tended to increase during the period of study; -, trend slope indicates that the time of measurement tended to decrease during the period of study] 

Station 

number

Results of Seasonal Kendall trend tests of flow-adjusted values of pH Results of tests to assess the effects of trends in time of measurement on the results of trend tests of flow-adjusted values of pH

Summary 

result

Trend slope Kendall tau tests for correlation of pH and time of measurement Seasonal Kendall trend tests of time of measurement of pH

Level of 

significance 

In standard 

units per year

In percent of median value 

per year (median value in 

standard units)

Summary 

result

Level of 

significance

Summary 

result

Trend slope

Level of 

significance Direction 

Passaic Water Region

01377000 -- 0.481 0.005 0.1 (7.7) -- (c) 0.463 Decrease (t) 0.050 -01378560 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01378780 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01379200 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01380100 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01381800 -- 0.084 0.016 0.2 (7.4) -- (c) 0.568 -- (t) 0.849 n.d.01382000 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01382500 -- 0.168 -0.007 -0.1 (7.6) -- (c) 0.785 -- (t) 0.184 n.d.01387500 -- 0.296 -0.013 -0.2 (7.7) -- (c) 0.557 -- (t) 0.834 n.d.01388500 -- 0.186 -0.032 -0.4 (7.6) -- (c) 0.167 Decrease (t) 0.025 -01389500 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01391500 -- 0.125 0.037 0.5 (7.7) -- (c) 0.258 -- (t) 0.645 +

Raritan Water Region

01394500 Increase 0.044 0.017 0.2 (7.6) -- (c) 0.480 Decrease (t) 0.008 -01395000 -- 0.187 0.019 0.2 (7.8) -- (c) 0.584 -- (t) 0.661 -01396660 -- 0.884 0.000 0.0 (7.8) -- (c) 0.799 -- (t) 0.309 n.d.01398000 -- 0.097 0.041 0.5 (8) -- (c) 0.713 Decrease (t) 0.048 -01398102 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01399780 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01400000 -- 0.211 0.014 0.2 (7.8) -- (c) 0.712 Decrease (t) 0.026 -01400640 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01401400 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01402000 -- 0.055 -0.022 -0.3 (7.4) -- (c) 0.223 Decrease (t) 0.003 -01403385 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01405340 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.
54 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007 Table 7. Results of trend tests on flow-adjusted values of pH at water-quality stations on New Jersey streams, water years 1998–2007.—Continued [--, no trend in flow-adjusted values of pH during the period of study was identified at a 0.05 level of significance; Decrease, pH decreased during the period of study; Increase, pH increased during the period of study; n.d., not determined; results of trend tests of flow-adjusted values of pH are not presented if (a) pH values were affected by a change in field methods or (b) pH correlated with time of measurement and there was a trend in time of measurement; -- (c), no correlation at the 0.05 level of significance was identified between values of pH and time of measurement; Decrease (c), pH decreased with increasing time of measurement; -- (t), no trend in time of measurement during the period of study was identified at a 0.05 level of significance; Decrease (t), time of measurement decreased during the period of study; +, trend slope indicates that the time of measurement tended to increase during the period of study; -, trend slope indicates that the time of measurement tended to decrease during the period of study] Station number Results of Seasonal Kendall trend tests of flow-adjusted values of pH Results of tests to assess the effects of trends in time of measurement on the results of trend tests of flow-adjusted values of pH Summary result Trend slope Kendall tau tests for correlation of pH and time of measurement Seasonal Kendall trend tests of time of measurement of pH Level of significance In standard units per year In percent of median value per year (median value in standard units) Summary result Level of significance Summary result Trend slope Level of significance Direction Atlantic Coastal Water Region 01408000 Decrease 0.025 -0.028 -0.4 (7.2) -- (c) 0.848 Decrease (t) 0.002 - 01408009 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d. 01408100 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d. 01408500 Increase 0.048 0.039 0.7 (5.8) -- (c) 0.145 -- (t) 0.062 - 01408830 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d. 01409387 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d. 0140940950 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d. 01409416 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d. 01409500 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d. 01409815 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d. 01410150 -- 0.511 -0.006 -0.1 (4.4) -- (c) 0.342 Decrease (t) 0.043 - 01411035 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.

01411110 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.

01411196 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.

01411400 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01411444 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.

Upper Delaware Water Region

01367625 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01367770 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01367800 -- 0.961 0.000 0.0 (7.8) -- (c) 0.711 -- (t) 0.103 -01368820 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01438500 Decrease 0.037 -0.019 -0.3 (7.3) -- (c) 0.164 -- (t) 0.181 -01440000 -- 0.079 0.019 0.2 (7.9) -- (c) 0.163 Decrease (t) 0.001 -01442760 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01443000 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01443500 -- 0.229 0.010 0.1 (8.2) -- (c) 0.338 -- (t) 0.197 -
Table 7 55

Table 7. Results of trend tests on flow-adjusted values of pH at water-quality stations on New Jersey streams, water years 1998–2007.—Continued[--, no trend in flow-adjusted values of pH during the period of study was identified at a 0.05 level of significance; Decrease, pH decreased during the period of study; Increase, pH increased during the period of study; n.d., not determined; results of trend tests of flow-adjusted values of pH are not presented if (a) pH values were affected by a change in field methods or (b) pH correlated with time of measurement and there was a trend in time of measurement; -- (c), no correlation at the 0.05 level of significance was identified between values of pH and time of measurement; Decrease (c), pH decreased with increasing time of measurement; -- (t), no trend in time of measurement during the period of study was identified at a 0.05 level of significance; Decrease (t), time of measurement decreased during the period of study; +, trend slope indicates that the time of measurement tended to increase during the period of study; -, trend slope indicates that the time of measurement tended to decrease during the period of study] 

Station 

number

Results of Seasonal Kendall trend tests of flow-adjusted values of pH Results of tests to assess the effects of trends in time of measurement on the results of trend tests of flow-adjusted values of pH

Summary 

result

Trend slope Kendall tau tests for correlation of pH and time of measurement Seasonal Kendall trend tests of time of measurement of pH

Level of 

significance 

In standard 

units per year

In percent of median value 

per year (median value in 

standard units)

Summary 

result

Level of 

significance

Summary 

result

Trend slope

Level of 

significance Direction 

Upper Delaware Water Region

01446400 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01457400 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01457500 -- 0.075 0.027 0.4 (7.8) -- (c) 0.568 Decrease (t) 0.025 -01458570 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01461000 Increase 0.002 0.069 0.9 (7.9) Decrease (c) 0.006 -- (t) 0.062 -01463500 -- 0.374 0.023 0.3 (7.8) -- (c) 0.184 -- (t) 0.053 -01463850 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01464020 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.

Lower Delaware Water Region

01411466 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01411500 -- 0.568 0.015 0.2 (6.4) -- (c) 0.408 Decrease (t) 0.036 -01411955 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.

01412800 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01464504 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01464515 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01465893 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01466500 -- 0.804 0.000 0.0 (4.2) -- (c) 0.820 Decrease (t) 0.022 -01467005 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01467150 n.d. n.d. n.d. n.d. (n.d.) Decrease (c) 0.018 Decrease (t) 0.017 -01467359 n.d. n.d. n.d. n.d. (n.d.) n.d. n.d. n.d. n.d. n.d.01477120 -- 0.628 0.007 0.1 (7.2) -- (c) 0.207 -- (t) 0.167 n.d.01482500 -- 0.147 0.050 0.7 (7.4) -- (c) 0.155 -- (t) 0.968 n.d.
56 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Table 8. Summary statistics for total dissolved solids at water-quality stations on New Jersey streams, water years 

1998–2007.—Continued

[n.a., not applicable; <, less than]

Station 

number

Results of 

trend tests 

presented

Number of 

measurements

Nondetect measurements Statistic, in milligrams per liter

Number

Percentage 

of all 

measurements

Maximum 

reporting level, 

in milligrams 

per liter

Minimum 25th 

percentile Median 75th percentile Maximum

Passaic Water Region

01377000 Yes 40 0 0 n.a. 122 229 253 288 425

01378560 Yes 39 0 0 n.a. 76 257 369 434 1,245

01378780 Yes 40 0 0 n.a. 70 84 90 100 109

01379200 Yes 40 0 0 n.a. 140 269 332 387 1,040

01380100 Yes 40 0 0 n.a. 78 106 122 136 168

01381800 Yes 40 0 0 n.a. 136 274 331 387 755

01382000 Yes 40 0 0 n.a. 141 252 314 389 780

01382500 Yes 39 0 0 n.a. 78 94 122 139 218

01387500 Yes 40 0 0 n.a. 105 199 247 305 416

01388500 Yes 40 0 0 n.a. 92 164 228 247 336

01389500 Yes 40 0 0 n.a. 133 229 291 338 645

01391500 Yes 39 0 0 n.a. 199 408 449 500 819

Raritan Water Region

01394500 Yes 40 0 0 n.a. 123 365 398 460 2,296

01395000 Yes 40 0 0 n.a. 156 276 344 406 651

01396660 Yes 40 0 0 n.a. 113 139 149 159 200

01398000 Yes 38 0 0 n.a. 126 168 192 224 688

01398102 Yes 40 0 0 n.a. 114 146 170 181 279

01399780 Yes 39 0 0 n.a. 72 129 152 172 234

01400000 Yes 40 0 0 n.a. 101 147 167 187 293

01400640 Yes 36 0 0 n.a. 117 147 162 183 237

01401400 Yes 39 0 0 n.a. 100 136 156 193 647

01402000 Yes 39 0 0 n.a. 107 144 183 213 415

01403385 Yes 39 0 0 n.a. 27 218 305 382 652

01405340 Yes 40 0 0 n.a. 76 112 127 140 171

Atlantic Coastal Water Region

01408000 Yes 40 0 0 n.a. 82 130 150 166 1,307

01408009 Yes 40 0 0 n.a. 56 76 87 98 149

01408100 Yes 40 0 0 n.a. 47 88 101 114 192

01408500 Yes 40 0 0 n.a. 45 59 65 71 85

01408830 Yes 40 0 0 n.a. 15 21 24 27 40

01409387 Yes 40 0 0 n.a. 16 30 34 40 59

0140940950 Yes 40 0 0 n.a. 36 46 51 59 79

01409416 Yes 40 0 0 n.a. 53 76 80 87 105

01409500 Yes 37 0 0 n.a. 19 31 36 42 51

01409815 Yes 40 0 0 n.a. 20 26 28 31 41

01410150 Yes 40 1 3 10 <10 25 29 34 52

01411035 Yes 40 0 0 n.a. 36 46 50 54 70

01411110 Yes 40 0 0 n.a. 25 44 50 59 73

01411196 Yes 40 0 0 n.a. 32 40 47 55 93

01411400 Yes 40 0 0 n.a. 81 106 122 134 213

01411444 Yes 36 0 0 n.a. 23 39 41 49 84
Table 8 57

Table 8. Summary statistics for total dissolved solids at water-quality stations on New Jersey streams, water years 

1998–2007.—Continued

[n.a., not applicable; <, less than]

Station 

number

Results of 

trend tests 

presented

Number of 

measurements

Nondetect measurements Statistic, in milligrams per liter

Number

Percentage 

of all 

measurements

Maximum 

reporting level, 

in milligrams 

per liter

Minimum 25th 

percentile Median 75th percentile Maximum

Upper Delaware Water Region

01367625 Yes 40 0 0 n.a. 292 343 360 405 480

01367770 Yes 39 0 0 n.a. 195 269 326 362 514

01367800 Yes 36 0 0 n.a. 129 178 206 245 277

01368820 Yes 39 0 0 n.a. 12 128 140 154 179

01438500 Yes 40 0 0 n.a. 37 46 52 58 71

01440000 Yes 39 0 0 n.a. 57 100 110 129 176

01442760 Yes 38 0 0 n.a. 18 23 25 27 31

01443000 Yes 39 0 0 n.a. 47 50 57 63 75

01443500 Yes 40 0 0 n.a. 177 226 249 280 326

01446400 Yes 40 0 0 n.a. 27 263 291 306 348

01457400 Yes 40 0 0 n.a. 124 216 234 250 268

01457500 Yes 40 0 0 n.a. 68 91 110 122 163

01458570 Yes 40 0 0 n.a. 89 105 112 117 136

01461000 Yes 40 0 0 n.a. 61 94 118 129 148

01463500 Yes 39 0 0 n.a. 67 90 114 124 149

01463850 Yes 40 0 0 n.a. 68 100 117 138 285

01464020 Yes 40 0 0 n.a. 101 176 215 248 453

Lower Delaware Water Region

01411466 Yes 39 0 0 n.a. 29 39 46 56 74

01411500 Yes 36 0 0 n.a. 52 64 70 80 88

01411955 Yes 40 0 0 n.a. 15 21 25 30 56

01412800 Yes 40 0 0 n.a. 86 125 132 140 173

01464504 Yes 39 0 0 n.a. 71 104 115 134 177

01464515 Yes 40 0 0 n.a. 80 111 119 132 157

01465893 Yes 39 0 0 n.a. 51 58 67 74 86

01466500 Yes 40 0 0 n.a. 11 22 27 33 52

01467005 Yes 40 0 0 n.a. 53 77 87 100 135

01467150 Yes 40 0 0 n.a. 98 133 149 179 1,543

01467359 Yes 40 0 0 n.a. 58 102 112 126 406

01477120 Yes 40 0 0 n.a. 105 129 137 145 223

01482500 Yes 40 0 0 n.a. 117 155 160 168 182
58 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Station 

number

Results of Seasonal Kendall trend tests of 

flow-adjusted concentrations of total dissolved solids

Summary 

result

Trend slope

Level of 

significance

In milligrams 

per liter 

per year

In percent of median 

value per year 

(median value in 

milligrams per liter)

Passaic Water Region

01377000 -- 0.918 -0.4 -0.2 (253)

01378560 -- 0.065 15.6 4.2 (369)

01378780 -- 0.143 0.5 0.5 (90)

01379200 Increase 0.038 8.6 2.6 (332)

01380100 -- 0.752 -0.3 -0.2 (122)

01381800 Increase 0.014 9.6 2.9 (331)

01382000 -- 0.330 2.0 0.6 (314)

01382500 -- 0.368 0.7 0.6 (122)

01387500 -- 0.078 3.7 1.5 (247)

01388500 -- 0.409 2.4 1.0 (228)

01389500 -- 0.125 5.6 1.9 (291)

01391500 Increase 0.006 9.0 2.0 (449)

Raritan Water Region

01394500 Increase 0.020 9.9 2.5 (398)

01395000 Increase 0.048 12.9 3.7 (344)

01396660 -- 0.963 0.1 0.0 (149)

01398000 -- 0.188 2.6 1.3 (192)

01398102 Increase 0.014 2.0 1.2 (170)

01399780 Increase 0.033 4.3 2.8 (152)

01400000 Increase 0.048 4.9 2.9 (167)

01400640 -- 0.176 1.3 0.8 (162)

01401400 Increase 0.002 8.3 5.3 (156)

01402000 -- 0.052 5.0 2.7 (183)

01403385 -- 0.084 6.7 2.2 (305)

01405340 Increase 0.002 4.8 3.8 (127)

Atlantic Coastal Water Region

01408000 Increase 0.004 5.7 3.8 (150)

01408009 -- 0.191 0.7 0.8 (87)

01408100 Increase 0.009 3.9 3.8 (101)

01408500 Increase 0.003 1.4 2.2 (65)

01408830 -- 0.706 0.1 0.5 (24)

01409387 -- 0.141 1.1 3.1 (34)

0140940950 Increase 0.041 1.4 2.7 (51)

01409416 Increase 0.040 0.9 1.2 (80)

01409500 -- 0.404 0.4 1.1 (36)

01409815 -- 0.836 0.2 0.6 (28)

01410150 Increase 0.048 0.6 1.9 (29)

01411035 -- 0.656 -0.2 -0.4 (50)

01411110 Increase 0.013 1.1 2.2 (50)

01411196 -- 0.053 1.2 2.5 (47)

01411400 -- 0.064 -1.6 -1.3 (122)

01411444 -- 0.596 0.5 1.1 (42)

Table 9. Results of trend tests on flow-adjusted concentrations of total dissolved solids at water-quality stations on New Jersey 

streams, water years 1998–2007.

[--, no trend in flow-adjusted concentrations of total dissolved solids during the period of study was identified at a 0.05 level of significance; Increase, concentrations of total dissolved solids increased during the period of study]

Station 

number

Results of Seasonal Kendall trend tests of 

flow-adjusted concentrations of total dissolved solids

Summary 

result

Trend slope

Level of 

significance

In milligrams 

per liter 

per year

In percent of median 

value per year 

(median value in 

milligrams per liter)

Upper Delaware Water Region

01367625 -- 0.977 0.4 0.1 (360)

01367770 -- 0.417 1.4 0.4 (326)

01367800 -- 0.443 -1.5 -0.7 (206)

01368820 -- 0.180 1.6 1.2 (140)

01438500 -- 0.276 -0.5 -0.9 (52)

01440000 -- 0.409 0.7 0.7 (110)

01442760 -- 0.132 0.3 1.2 (25)

01443000 -- 0.750 -0.0 0.0 (57)

01443500 -- 0.842 -0.4 -0.2 (249)

01446400 -- 0.701 0.5 0.2 (291)

01457400 -- 0.187 1.1 0.5 (234)

01457500 -- 0.196 1.3 1.2 (110)

01458570 -- 0.891 -0.2 -0.2 (112)

01461000 -- 0.635 0.1 0.1 (118)

01463500 -- 0.653 -0.7 -0.6 (114)

01463850 Increase 0.004 2.9 2.5 (117)

01464020 Increase 0.006 5.4 2.5 (215)

Lower Delaware River Basin

01411466 -- 0.859 0.0 0.1 (46)

01411500 -- 0.056 1.6 2.2 (70)

01411955 -- 0.978 0.1 0.4 (25)

01412800 -- 0.133 1.1 0.9 (132)

01464504 Increase 0.050 2.1 1.8 (115)

01464515 -- 0.111 1.1 0.9 (119)

01465893 -- 0.154 1.2 1.8 (67)

01466500 -- 0.650 0.1 0.5 (27)

01467005 -- 0.106 -0.6 -0.7 (87)

01467150 Increase 0.006 4.9 3.3 (149)

01467359 Increase 0.015 2.4 2.1 (112)

01477120 Increase 0.016 1.4 1.0 (137)

01482500 Increase 0.008 1.5 0.9 (160)
Table 10 59

Table 10. Summary statistics for total phosphorus at water-quality stations on New Jersey streams, water years 

1998–2007.—Continued

[n.a., not applicable; <, less than; E, estimated]

Station 

number

Results of 

trend tests 

presented

Number of 

measurements

Nondetect measurements Statistic, in milligrams per liter as P

Number

Percentage 

of all 

measurements

Maximum 

reporting level, 

in milligrams 

per liter as P

Minimum 25th 

percentile Median 75th percentile Maximum

Passaic Water Region

01377000 Yes 39 0 0 n.a. 0.018 0.035 0.046 0.069 0.194

01378560 Yes 38 0 0 n.a. 0.018 0.043 0.069 0.129 0.285

01378780 Yes 40 4 10 0.025 < 0.004 0.006 0.011 0.021 0.064

01379200 Yes 40 0 0 n.a. 0.061 0.306 0.712 1.226 3.467

01380100 Yes 40 3 8 0.025 < 0.01 0.017 0.027 0.041 0.176

01381800 Yes 40 0 0 n.a. 0.051 0.105 0.197 0.294 0.643

01382000 Yes 39 0 0 n.a. 0.138 0.347 0.488 0.761 1.65

01382500 Yes 40 4 10 0.025 < 0.001 0.012 0.018 0.021 E 0.044

01387500 Yes 40 0 0 n.a. E 0.035 0.083 0.113 0.239 0.749

01388500 Yes 40 0 0 n.a. 0.014 0.036 0.056 0.076 0.168

01389500 Yes 40 0 0 n.a. 0.06 0.208 0.32 0.479 1.319

01391500 Yes 40 0 0 n.a. 0.28 0.467 0.748 1.125 1.776

Raritan Water Region

01394500 Yes 40 0 0 n.a. 0.02 0.05 0.067 0.102 0.222

01395000 Yes 39 0 0 n.a. 0.018 0.066 0.104 0.123 0.184

01396660 Yes 40 4 10 0.05 < 0.01 0.01 0.012 0.021 0.65

01398000 Yes 39 6 15 0.03 < 0.02 0.027 0.045 0.074 0.196

01398102 Yes 40 0 0 n.a. 0.022 0.057 0.076 0.107 0.286

01399780 Yes 39 1 3 0.025 < 0.025 0.038 0.052 0.09 0.261

01400000 Yes 40 2 5 0.03 < 0.025 0.029 0.048 0.073 0.262

01400640 Yes 36 0 0 n.a. 0.014 0.06 0.092 0.135 0.21

01401400 Yes 39 1 3 0.025 < 0.025 0.016 0.032 0.055 0.16

01402000 Yes 39 0 0 n.a. 0.129 0.187 0.238 0.361 0.811

01403385 Yes 40 0 0 n.a. 0.014 0.066 0.1 0.144 0.303

01405340 Yes 39 0 0 n.a. 0.009 0.053 0.066 0.095 0.433

Atlantic Coastal Water Region

01408000 Yes 40 2 5 0.025 < 0.025 0.034 0.044 0.064 0.195

01408009 Yes 40 4 10 0.025 < 0.01 0.03 0.039 0.06 0.197

01408100 Yes 40 2 5 0.025 < 0.025 0.032 0.04 0.052 0.093

01408500 Yes 40 5 13 0.025 < 0.01 0.013 0.02 0.03 0.066

01408830 Yes 40 19 48 0.025 < 0.002 0.002 0.003 0.005 0.031

01409387 Yes 40 11 28 0.025 < 0.001 0.005 0.007 0.014 0.047

0140940950 Yes 40 2 5 0.025 < 0.025 0.021 0.032 0.042 0.139

01409416 Yes 40 0 0 n.a. E 0.032 0.087 0.171 0.226 0.958

01409500 Yes 37 9 24 0.025 < 0.001 0.004 0.009 0.011 0.027

01409815 Yes 40 4 10 0.025 < 0.01 0.02 0.033 0.064 0.12

01410150 Yes 40 20 50 0.025 < 0.001 0.002 0.003 0.003 0.012

01411035 Yes 40 5 13 0.025 < 0.01 0.011 0.017 0.023 E 0.039

01411110 Yes 40 8 20 0.025 < 0.001 0.01 0.014 0.025 0.067

01411196 Yes 40 5 13 0.025 < 0.01 0.007 0.01 0.015 E 0.036

01411400 Yes 40 6 15 0.025 < 0.001 0.011 0.026 0.044 0.088

01411444 Yes 35 7 20 0.025 < 0.001 0.005 0.007 0.009 0.015
60 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Table 10. Summary statistics for total phosphorus at water-quality stations on New Jersey streams, water years 

1998–2007.—Continued

[n.a., not applicable; <, less than; E, estimated]

Station 

number

Results of 

trend tests 

presented

Number of 

measurements

Nondetect measurements Statistic, in milligrams per liter as P

Number

Percentage 

of all 

measurements

Maximum 

reporting level, 

in milligrams 

per liter as P

Minimum 25th 

percentile Median 75th percentile Maximum

Upper Delaware Water Region

01367625 Yes 40 3 8 0.025 < 0.025 0.024 0.031 0.055 0.199

01367770 Yes 39 3 8 0.025 < 0.01 0.023 0.033 0.054 0.107

01367800 Yes 35 3 9 0.025 < 0.025 0.015 0.032 0.043 0.06

01368820 Yes 39 5 13 0.025 < 0.01 0.011 0.015 0.022 E 0.036

01438500 Yes 40 4 10 0.05 < 0.025 0.011 0.017 0.026 0.132

01440000 Yes 40 7 18 0.025 < 0.01 0.006 0.008 0.01 0.025

01442760 Yes 40 20 50 0.025 < 0.001 0.001 0.002 0.005 0.02

01443000 Yes 40 3 8 0.025 < 0.01 0.014 0.017 0.025 0.061

01443500 Yes 40 2 5 0.025 < 0.01 0.019 0.028 0.042 0.065

01446400 Yes 40 0 0 n.a. 0.021 0.039 0.052 0.077 0.329

01457400 Yes 40 5 13 0.025 < 0.01 0.017 0.026 0.043 0.172

01457500 Yes 39 0 0 n.a. 0.024 0.042 0.058 0.073 0.151

01458570 Yes 40 3 8 0.025 < 0.01 0.019 0.03 0.048 0.128

01461000 Yes 40 0 0 n.a. 0.019 0.039 0.05 0.075 0.19

01463500 Yes 39 0 0 n.a. 0.019 0.036 0.061 0.087 0.138

01463850 Yes 37 1 3 0.025 < 0.025 0.038 0.053 0.081 0.419

01464020 Yes 40 0 0 n.a. 0.158 0.304 0.522 0.815 1.762

Lower Delaware Water Region

01411466 Yes 39 10 26 0.025 < 0.004 0.005 0.008 0.012 0.044

01411500 Yes 36 4 11 0.025 < 0.025 0.009 0.014 0.02 0.04

01411955 Yes 40 9 23 0.025 < 0.001 0.003 0.005 0.007 0.032

01412800 Yes 39 0 0 n.a. 0.028 0.038 0.056 0.079 0.287

01464504 Yes 39 0 0 n.a. 0.011 0.083 0.126 0.193 0.347

01464515 Yes 40 0 0 n.a. 0.004 0.055 0.07 0.097 0.256

01465893 Yes 39 3 8 0.025 < 0.025 0.013 0.022 0.036 0.104

01466500 No 40 32 80 0.05 < 0.001 0.001 0.002 0.002 0.005

01467005 Yes 38 0 0 n.a. 0.04 0.107 0.165 0.241 0.316

01467150 Yes 40 0 0 n.a. 0.018 0.157 0.232 0.287 0.401

01467359 Yes 40 0 0 n.a. 0.028 0.164 0.214 0.246 0.339

01477120 Yes 40 0 0 n.a. 0.018 0.09 0.129 0.182 0.342

01482500 Yes 39 0 0 n.a. 0.035 0.13 0.175 0.238 0.538
Table 11 61

Table 11. Results of trend tests on flow-adjusted concentrations of total phosphorus at water-quality stations on New Jersey streams, 

water years 1998–2007.—Continued

[--, no trend in the flow-adjusted concentrations of total phosphorus during the period of study was identified at a 0.05 level of significance ; Decrease, total 

phosphorus decreased during the period of study; Increase, total phosphorus increased during the period of study; n.d., not determined] 

Station 

number

Whether a single 

outlying point was 

dropped from test

Results of Tobit regression trend tests on flow-adjusted concentrations of total phosphorus

Summary 

result

Trend slope

Level of 

significance

In milligrams per liter 

as P per year

In percent of mean value per year 

(mean value in milligrams per liter as P)

Passaic Water Region

01377000 No -- 0.414 0.001 1.9 (0.06)

01378560 No -- 0.994 0.000 0.0 (0.092)

01378780 No -- 0.527 0.000 -2.2 (0.016)

01379200 Yes Decrease 0.002 -0.055 -5.9 (0.94)

01380100 No -- 0.184 0.001 3.3 (0.033)

01381800 No Decrease 0.000 -0.022 -9.7 (0.22)

01382000 No Decrease 0.003 -0.027 -4.9 (0.56)

01382500 No -- 0.265 -0.001 -3.7 (0.019)

01387500 No -- 0.585 -0.002 -1.0 (0.19)

01388500 No -- 0.304 -0.001 -2.3 (0.059)

01389500 No -- 0.089 -0.011 -2.8 (0.4)

01391500 No -- 0.977 0.000 0.1 (0.85)

Raritan Water Region

01394500 No -- 0.227 0.002 2.5 (0.077)

01395000 No -- 0.447 -0.001 -1.5 (0.099)

01396660 No -- 0.107 -0.003 -7.5 (0.035)

01398000 No -- 0.169 -0.003 -5.1 (0.06)

01398102 No -- 0.421 -0.002 -2.2 (0.083)

01399780 No -- 0.113 -0.004 -5.3 (0.07)

01400000 No -- 0.143 -0.003 -4.6 (0.06)

01400640 No Decrease 0.000 -0.012 -12.1 (0.098)

01401400 No -- 0.983 0.000 0.1 (0.041)

01402000 No -- 0.122 -0.009 -2.8 (0.3)

01403385 No Decrease 0.002 -0.008 -7.8 (0.11)

01405340 No -- 0.475 -0.001 -1.9 (0.08)

Atlantic Coastal Water Region

01408000 No -- 0.973 0.000 -0.1 (0.06)

01408009 No Increase 0.011 0.004 8.6 (0.05)

01408100 No -- 0.873 0.000 0.5 (0.042)

01408500 Yes Decrease 0.034 -0.001 -3.6 (0.024)

01408830 No -- 0.236 0.000 -5.4 (0.007)

01409387 No -- 0.318 -0.001 -4.1 (0.013)

0140940950 No -- 0.432 0.001 1.6 (0.035)

01409416 No -- 0.899 -0.001 -0.4 (0.21)

01409500 No -- 0.120 0.001 6.3 (0.012)

01409815 Yes Increase 0.016 0.003 5.9 (0.045)

01410150 No -- 0.422 0.000 3.5 (0.006)

01411035 No -- 0.205 0.001 2.8 (0.019)

01411110 No -- 0.142 0.001 6.0 (0.019)

01411196 No -- 0.190 0.000 -3.4 (0.013)

01411400 Yes Increase 0.029 0.002 7.0 (0.031)

01411444 No -- 0.149 -0.001 -5.7 (0.009)
62 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Table 11. Results of trend tests on flow-adjusted concentrations of total phosphorus at water-quality stations on New Jersey streams, 

water years 1998–2007.—Continued

[--, no trend in the flow-adjusted concentrations of total phosphorus during the period of study was identified at a 0.05 level of significance ; Decrease, total 

phosphorus decreased during the period of study; Increase, total phosphorus increased during the period of study; n.d., not determined] 

Station 

number

Whether a single 

outlying point was 

dropped from test

Results of Tobit regression trend tests on flow-adjusted concentrations of total phosphorus

Summary 

result

Trend slope

Level of 

significance

In milligrams per liter 

as P per year

In percent of mean value per year 

(mean value in milligrams per liter as P)

Upper Delaware Water Region

01367625 Yes Increase 0.004 0.003 6.0 (0.042)

01367770 No -- 0.136 0.001 2.6 (0.042)

01367800 No -- 0.368 0.001 1.7 (0.031)

01368820 No -- 0.277 0.000 -1.4 (0.018)

01438500 No Decrease 0.002 -0.002 -8.0 (0.026)

01440000 No -- 0.361 0.000 2.2 (0.011)

01442760 No -- 0.248 0.000 -6.8 (0.007)

01443000 No -- 0.989 0.000 0.1 (0.021)

01443500 No -- 0.127 -0.001 -2.6 (0.031)

01446400 No -- 0.147 -0.004 -4.7 (0.078)

01457400 Yes Decrease 0.007 -0.003 -8.5 (0.039)

01457500 Yes Decrease 0.003 -0.003 -4.1 (0.064)

01458570 No -- 0.443 -0.001 -2.1 (0.037)

01461000 No Decrease 0.006 -0.004 -6.1 (0.062)

01463500 No Decrease 0.000 -0.005 -8.1 (0.063)

01463850 No -- 0.190 0.003 4.8 (0.07)

01464020 No Decrease 0.002 -0.018 -3.0 (0.6)

Lower Delaware Water Region

01411466 No -- 0.053 0.001 5.9 (0.011)

01411500 No -- 0.462 0.000 -1.2 (0.017)

01411955 No -- 0.167 -0.001 -6.2 (0.009)

01412800 No -- 0.386 -0.002 -2.4 (0.07)

01464504 No -- 0.699 0.002 1.1 (0.14)

01464515 No -- 0.328 -0.003 -3.7 (0.081)

01465893 No -- 0.081 0.001 4.7 (0.028)

01466500 n.d. n.d. n.d. n.d. n.d. (n.d.)

01467005 No Increase 0.001 0.011 6.7 (0.17)

01467150 No -- 0.754 -0.002 -0.9 (0.22)

01467359 No -- 0.133 -0.008 -4.0 (0.21)

01477120 No -- 0.051 -0.007 -5.1 (0.14)

01482500 No -- 0.873 -0.001 -0.4 (0.19)
Table 12 63

Table 12. Summary statistics for total organic nitrogen plus ammonia at water-quality stations on New Jersey streams, 

water years 1998–2007.—Continued

[n.a., not applicable; <, less than; ]

Station 

number

Results of 

trend tests 

presented

Number of 

measurements

Nondetect measurements Statistic, in milligrams per liter as N

Number

Percentage 

of all 

measurements

Maximum 

reporting level, 

in milligrams 

per liter as N

Minimum 25th 

percentile Median 75th percentile Maximum

Passaic Water Region

01377000 Yes 39 0 0 n.a. 0.5 0.56 0.69 0.96 1.9

01378560 Yes 38 0 0 n.a. 0.3 0.44 0.53 0.73 1.31

01378780 Yes 40 19 48 0.21 < 0.05 0.06 0.09 0.13 0.3

01379200 Yes 39 0 0 n.a. 0.24 0.39 0.59 0.8 1.66

01380100 Yes 40 1 3 0.14 < 0.14 0.25 0.34 0.39 0.63

01381800 Yes 40 0 0 n.a. 0.43 0.54 0.63 0.77 1.04

01382000 Yes 40 0 0 n.a. 0.36 0.6 0.7 0.78 1.57

01382500 Yes 40 4 10 0.2 < 0.15 0.21 0.3 0.44 1.49

01387500 Yes 40 0 0 n.a. 0.19 0.34 0.47 0.56 4.46

01388500 Yes 40 0 0 n.a. 0.25 0.41 0.51 0.64 1.54

01389500 Yes 40 0 0 n.a. 0.32 0.51 0.61 0.72 1.21

01391500 Yes 40 0 0 n.a. 0.56 0.76 1.02 1.41 3.35

Raritan Water Region

01394500 Yes 40 1 3 0.14 < 0.14 0.28 0.36 0.54 0.8

01395000 Yes 40 0 0 n.a. 0.27 0.38 0.48 0.61 0.88

01396660 Yes 40 14 35 0.22 < 0.1 0.11 0.13 0.19 1.18

01398000 Yes 39 2 5 0.17 < 0.17 0.27 0.33 0.47 0.81

01398102 Yes 40 2 5 0.15 < 0.14 0.29 0.35 0.47 0.8

01399780 Yes 39 5 13 0.22 < 0.12 0.18 0.31 0.41 1.1

01400000 Yes 40 3 8 0.22 < 0.12 0.24 0.29 0.36 1.11

01400640 Yes 35 0 0 n.a. 0.34 0.43 0.49 0.6 1.32

01401400 Yes 39 2 5 0.2 < 0.2 0.25 0.34 0.49 1.11

01402000 Yes 39 0 0 n.a. 0.39 0.49 0.6 0.77 1.37

01403385 Yes 40 0 0 n.a. 0.42 0.53 0.59 0.68 1.37

01405340 Yes 40 0 0 n.a. 0.18 0.28 0.37 0.44 0.86

Atlantic Coastal Water Region

01408000 Yes 40 2 5 0.1 < 0.05 0.19 0.29 0.49 1.38

01408009 Yes 40 5 13 0.23 < 0.05 0.13 0.23 0.33 0.9

01408100 Yes 40 0 0 n.a. 0.15 0.3 0.35 0.45 0.72

01408500 Yes 40 0 0 n.a. 0.34 0.44 0.52 0.67 1.01

01408830 Yes 40 13 33 0.19 < 0.05 0.08 0.15 0.21 0.3

01409387 Yes 40 2 5 0.18 < 0.15 0.2 0.29 0.41 0.92

0140940950 Yes 40 0 0 n.a. 0.2 0.36 0.45 0.56 1.25

01409416 Yes 40 0 0 n.a. 0.21 0.32 0.36 0.5 1.55

01409500 Yes 37 3 8 0.2 < 0.13 0.17 0.24 0.33 0.79

01409815 Yes 40 1 3 0.12 < 0.12 0.19 0.24 0.33 0.69

01410150 Yes 40 15 38 0.21 < 0.05 0.09 0.11 0.18 0.38

01411035 Yes 40 1 3 0.11 < 0.11 0.2 0.28 0.4 0.96

01411110 Yes 40 1 3 0.19 < 0.19 0.23 0.32 0.39 0.79

01411196 Yes 40 3 8 0.17 < 0.11 0.22 0.28 0.35 0.53

01411400 Yes 40 0 0 n.a. 0.38 0.56 0.72 0.91 1.28

01411444 Yes 35 0 0 n.a. 0.15 0.29 0.34 0.43 1.09
64 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Table 12. Summary statistics for total organic nitrogen plus ammonia at water-quality stations on New Jersey streams, 

water years 1998–2007.—Continued

[n.a., not applicable; <, less than; ]

Station 

number

Results of 

trend tests 

presented

Number of 

measurements

Nondetect measurements Statistic, in milligrams per liter as N

Number

Percentage 

of all 

measurements

Maximum 

reporting level, 

in milligrams 

per liter as N

Minimum 25th 

percentile Median 75th percentile Maximum

Upper Delaware Water Region

01367625 Yes 40 0 0 n.a. 0.12 0.3 0.37 0.46 1.39

01367770 Yes 39 0 0 n.a. 0.2 0.3 0.38 0.46 0.66

01367800 Yes 36 2 6 0.21 < 0.18 0.25 0.34 0.38 0.73

01368820 Yes 39 0 0 n.a. 0.18 0.26 0.35 0.39 0.49

01438500 Yes 40 7 18 0.2 < 0.12 0.15 0.22 0.26 0.94

01440000 Yes 40 17 43 0.21 < 0.05 0.08 0.13 0.19 0.32

01442760 No 40 27 68 0.12 < 0.04 0.04 0.04 0.07 0.72

01443000 Yes 40 6 15 0.19 < 0.12 0.15 0.19 0.26 0.63

01443500 Yes 40 0 0 n.a. 0.23 0.34 0.38 0.45 0.69

01446400 Yes 40 0 0 n.a. 0.2 0.31 0.36 0.5 1.24

01457400 Yes 40 2 5 0.17 < 0.15 0.29 0.43 0.77 1.61

01457500 Yes 40 2 5 0.27 < 0.13 0.2 0.27 0.31 0.78

01458570 Yes 40 16 40 0.22 < 0.05 0.1 0.15 0.23 0.52

01461000 Yes 40 4 10 0.22 < 0.12 0.23 0.29 0.37 0.64

01463500 Yes 35 0 0 n.a. 0.16 0.24 0.28 0.41 0.95

01463850 Yes 40 0 0 n.a. 0.26 0.46 0.6 0.81 1.61

01464020 Yes 40 0 0 n.a. 0.46 0.6 0.71 0.83 1.08

Lower Delaware Water Region

01411466 Yes 39 1 3 0.17 < 0.17 0.26 0.32 0.46 0.87

01411500 Yes 36 0 0 n.a. 0.2 0.3 0.39 0.56 1.06

01411955 Yes 40 13 33 0.2 < 0.09 0.11 0.16 0.22 0.45

01412800 Yes 40 0 0 n.a. 0.26 0.37 0.48 0.56 1.61

01464504 Yes 39 0 0 n.a. 0.15 0.27 0.4 0.55 1.07

01464515 Yes 40 0 0 n.a. 0.48 0.73 0.88 1.12 2.77

01465893 Yes 39 0 0 n.a. 0.21 0.36 0.41 0.63 0.88

01466500 Yes 40 14 35 0.21 < 0.05 0.08 0.15 0.2 0.57

01467005 Yes 40 0 0 n.a. 0.4 0.6 0.7 0.78 0.98

01467150 Yes 40 0 0 n.a. 0.37 0.57 0.68 0.83 1.07

01467359 Yes 40 0 0 n.a. 0.25 0.41 0.46 0.56 0.7

01477120 Yes 40 0 0 n.a. 0.29 0.44 0.58 0.78 2.62

01482500 Yes 40 0 0 n.a. 0.69 1.07 1.25 1.49 2.68
Table 13 65

Table 13. Results of trend tests on flow-adjusted concentrations of total organic nitrogen plus ammonia at water-quality stations on 

New Jersey streams, water years 1998–2007.—Continued

[--, no trend in flow-adjusted concentrations of total organic nitrogen plus ammonia during the period of study was identified at a 0.05 level of significance; 

Decrease, total organic nitrogen plus ammonia decreased during the period of study; Increase, total organic nitrogen plus ammonia increased during the period 

of study; n.d., not determined] 

Station 

number

Whether a 

single outlying point was 

dropped from 

test

Results of Tobit regression trend tests on flow-adjusted concentrations of total organic nitrogen plus 

ammonia

Summary 

result

Trend slope

Level of 

significance 

In milligrams per liter 

as N per year

In percent of mean value per year 

(mean value in milligrams per liter as N)

Passaic Water Region

01377000 No -- 0.129 0.021 2.6 (0.81)

01378560 No -- 0.894 0.002 0.2 (0.62)

01378780 No -- 0.399 -0.003 -2.2 (0.13)

01379200 No -- 0.618 -0.005 -0.8 (0.64)

01380100 No -- 0.894 -0.001 -0.2 (0.33)

01381800 No -- 0.398 -0.007 -1.0 (0.67)

01382000 No -- 0.067 -0.012 -1.7 (0.71)

01382500 No Increase 0.001 0.036 9.6 (0.38)

01387500 Yes -- 0.077 0.029 4.9 (0.59)

01388500 No -- 0.061 0.022 3.7 (0.59)

01389500 No Decrease 0.020 -0.019 -2.9 (0.64)

01391500 No Decrease 0.000 -0.093 -7.6 (1.2)

Raritan Water Region

01394500 No -- 0.806 -0.002 -0.4 (0.42)

01395000 No -- 0.311 -0.007 -1.4 (0.5)

01396660 Yes -- 0.060 -0.008 -4.2 (0.19)

01398000 No -- 0.283 -0.008 -2.2 (0.38)

01398102 No -- 0.427 0.005 1.4 (0.39)

01399780 No -- 0.254 -0.009 -2.7 (0.35)

01400000 No -- 0.437 -0.005 -1.5 (0.35)

01400640 No -- 0.087 0.017 3.1 (0.55)

01401400 No -- 0.793 -0.002 -0.4 (0.4)

01402000 No -- 0.583 0.005 0.8 (0.64)

01403385 No -- 0.845 0.001 0.2 (0.63)

01405340 No -- 0.952 0.000 0.1 (0.38)

Atlantic Coastal Water Region

01408000 No Increase 0.000 0.041 11.4 (0.36)

01408009 No Increase 0.004 0.020 7.6 (0.26)

01408100 No -- 0.465 0.003 0.9 (0.38)

01408500 No -- 0.054 0.016 2.7 (0.57)

01408830 No -- 0.806 0.001 0.6 (0.17)

01409387 Yes -- 0.113 0.007 2.3 (0.32)

0140940950 No -- 0.439 0.006 1.2 (0.49)

01409416 No -- 0.256 0.009 2.0 (0.45)

01409500 No -- 0.380 0.006 2.1 (0.27)

01409815 Yes -- 0.143 0.006 2.3 (0.28)

01410150 No -- 0.478 0.003 2.0 (0.15)

01411035 No -- 0.798 -0.001 -0.4 (0.33)

01411110 Yes Increase 0.027 0.012 3.5 (0.34)

01411196 No -- 0.340 0.004 1.5 (0.28)

01411400 No -- 0.897 0.001 0.1 (0.74)

01411444 No -- 0.394 -0.007 -1.8 (0.37)
66 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Table 13. Results of trend tests on flow-adjusted concentrations of total organic nitrogen plus ammonia at water-quality stations on 

New Jersey streams, water years 1998–2007.—Continued

[--, no trend in flow-adjusted concentrations of total organic nitrogen plus ammonia during the period of study was identified at a 0.05 level of significance; 

Decrease, total organic nitrogen plus ammonia decreased during the period of study; Increase, total organic nitrogen plus ammonia increased during the period 

of study; n.d., not determined] 

Station 

number

Whether a 

single outlying point was 

dropped from 

test

Results of Tobit regression trend tests on flow-adjusted concentrations of total organic nitrogen plus 

ammonia

Summary 

result

Trend slope

Level of 

significance 

In milligrams per liter 

as N per year

In percent of mean value per year 

(mean value in milligrams per liter as N)

Upper Delaware Water Region

01367625 No -- 0.157 -0.012 -2.9 (0.43)

01367770 No -- 0.886 0.000 0.1 (0.4)

01367800 No Decrease 0.039 -0.008 -2.5 (0.33)

01368820 No -- 0.478 0.002 0.7 (0.33)

01438500 No -- 0.406 -0.004 -1.6 (0.25)

01440000 No -- 0.633 -0.002 -0.9 (0.17)

01442760 n.d. n.d. n.d. n.d. n.d. (n.d.)

01443000 Yes Increase 0.043 0.005 2.3 (0.21)

01443500 No Decrease 0.012 -0.010 -2.5 (0.4)

01446400 No -- 0.058 -0.016 -3.5 (0.44)

01457400 No Decrease 0.000 -0.059 -11.1 (0.53)

01457500 No -- 0.778 -0.001 -0.5 (0.28)

01458570 No -- 0.789 -0.002 -0.8 (0.2)

01461000 No -- 0.504 -0.004 -1.2 (0.32)

01463500 No -- 0.595 -0.003 -0.9 (0.34)

01463850 No -- 0.071 0.026 4.0 (0.67)

01464020 No Decrease 0.008 -0.018 -2.5 (0.72)

Lower Delaware Water Region

01411466 No -- 0.385 0.006 1.7 (0.36)

01411500 No Increase 0.006 0.023 5.1 (0.45)

01411955 No -- 0.259 -0.005 -2.9 (0.18)

01412800 No -- 0.463 -0.009 -1.7 (0.54)

01464504 No -- 0.064 0.015 3.5 (0.44)

01464515 No -- 0.532 0.009 0.9 (1)

01465893 Yes Increase 0.016 0.015 3.1 (0.49)

01466500 Yes -- 0.390 0.004 2.3 (0.18)

01467005 Yes Increase 0.032 0.012 1.8 (0.69)

01467150 Yes Increase 0.022 0.018 2.5 (0.7)

01467359 No -- 0.744 0.002 0.4 (0.47)

01477120 No -- 0.611 0.007 1.1 (0.65)

01482500 No -- 0.396 -0.020 -1.5 (1.4)
Table 14 67

Table 14. Summary statistics for dissolved nitrate plus nitrite at water-quality stations on New Jersey streams, 

water years 1998–2007.—Continued

[n.a., not applicable; <, less than; E, estimated; n.d., not determined]

Station 

number

Results of 

trend tests 

presented

Number 

of measurements

Nondetect measurements Statistic,in milligrams per liter as N

Number

Percentage 

of all 

measurements

Maximum 

reporting level, 

in milligrams 

per liter as N

Minimum 25th 

percentile Median 75th percentile Maximum

Passaic Water Region

01377000 Yes 39 0 0 n.a. 0.11 0.32 0.42 0.6 1.27

01378560 Yes 39 0 0 n.a. 0.09 0.73 0.97 1.53 2.16

01378780 Yes 40 0 0 n.a. 0.05 0.25 0.31 0.37 1.59

01379200 Yes 39 0 0 n.a. 1 1.7 2.76 4.78 13.14

01380100 Yes 40 1 3 0.03 < 0.03 0.1 0.16 0.23 0.36

01381800 Yes 40 0 0 n.a. 0.19 1.17 1.94 2.59 5.03

01382000 Yes 39 0 0 n.a. 0.41 1.48 2.44 3.65 6.62

01382500 Yes 40 0 0 n.a. 0.06 0.11 0.18 0.29 0.67

01387500 Yes 40 0 0 n.a. 0.37 0.74 1.08 2.26 4.93

01388500 Yes 40 0 0 n.a. 0.26 0.6 0.79 1.1 2.29

01389500 Yes 40 0 0 n.a. 0.58 1.46 1.98 3.05 7.93

01391500 Yes 40 0 0 n.a. 1.4 4.07 5.06 6.34 9.28

Raritan Water Region

01394500 Yes 40 0 0 n.a. 0.51 1.16 1.28 1.43 2.01

01395000 Yes 40 0 0 n.a. 0.39 0.75 1.08 1.22 1.61

01396660 Yes 40 0 0 n.a. 0.47 0.66 0.82 0.95 1.42

01398000 Yes 38 3 8 0.05 < 0.02 0.66 1.21 1.56 2.76

01398102 Yes 38 0 0 n.a. 0.39 1.16 1.4 1.64 2.37

01399780 Yes 39 0 0 n.a. 0.06 0.71 0.85 1.11 1.89

01400000 Yes 40 0 0 n.a. 0.21 0.73 0.95 1.1 1.35

01400640 Yes 36 0 0 n.a. 0.95 3.12 3.88 4.73 8.08

01401400 Yes 40 0 0 n.a. 0.22 1.19 2.73 4.07 5.9

01402000 Yes 40 0 0 n.a. 1.13 1.83 2.53 3.21 5.4

01403385 Yes 40 1 3 0.02 < 0.02 0.5 0.85 1.04 1.68

01405340 Yes 40 0 0 n.a. 0.49 0.63 0.78 1.04 2.02

Atlantic Coastal Water Region

01408000 Yes 39 0 0 n.a. 0.16 0.26 0.45 0.58 0.88

01408009 Yes 40 19 48 0.05 < 0.01 n.d. 0.03 0.06 0.14

01408100 Yes 40 0 0 n.a. 0.14 0.36 0.48 0.65 1.19

01408500 Yes 39 0 0 n.a. 0.11 0.42 0.59 0.72 1.19

01408830 No 40 33 83 0.05 < 0.01 n.d. n.d. n.d. 0.13

01409387 Yes 40 3 8 0.05 < 0.02 0.05 0.08 0.09 0.27

0140940950 Yes 39 13 33 0.05 < 0.01 0.02 0.15 0.29 1.13

01409416 Yes 40 0 0 n.a. 0.6 0.82 1.1 2 2.66

01409500 Yes 37 2 5 0.05 < 0.05 0.08 0.11 0.22 0.56

01409815 No 40 35 88 0.05 < 0.01 n.d. n.d. n.d. 0.07

01410150 No 40 34 85 0.05 < 0.01 n.d. n.d. n.d. 0.28

01411035 Yes 40 0 0 n.a. 0.37 0.65 0.96 1.42 2.04

01411110 Yes 40 0 0 n.a. 0.06 0.38 0.47 0.56 0.74

01411196 Yes 40 0 0 n.a. 0.2 0.41 0.51 0.64 E 0.85

01411400 Yes 40 15 38 0.05 < 0.02 n.d. 0.05 0.14 0.43

01411444 Yes 35 21 60 0.05 < 0.01 0.01 0.02 0.05 0.3
68 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Table 14. Summary statistics for dissolved nitrate plus nitrite at water-quality stations on New Jersey streams, 

water years 1998–2007.—Continued

[n.a., not applicable; <, less than; E, estimated; n.d., not determined]

Station 

number

Results of 

trend tests 

presented

Number 

of measurements

Nondetect measurements Statistic,in milligrams per liter as N

Number

Percentage 

of all 

measurements

Maximum 

reporting level, 

in milligrams 

per liter as N

Minimum 25th 

percentile Median 75th percentile Maximum

Upper Delaware Water Region

01367625 Yes 40 0 0 n.a. 0.16 0.37 0.5 0.66 1.4

01367770 Yes 39 0 0 n.a. 0.42 0.68 1.06 1.75 8.98

01367800 Yes 36 0 0 n.a. 0.37 0.57 0.82 1.26 1.76

01368820 Yes 39 14 36 0.05 < 0.01 0.02 0.03 0.09 0.19

01438500 Yes 40 0 0 n.a. E 0.06 0.16 0.21 0.29 0.43

01440000 Yes 40 12 30 0.05 < 0.02 n.d. 0.07 0.12 0.25

01442760 Yes 40 20 50 0.05 < 0.01 0.01 0.02 0.09 1.1

01443000 Yes 40 1 3 0.03 < 0.03 0.13 0.18 0.26 0.46

01443500 Yes 40 1 3 0.05 < 0.05 0.33 0.55 0.7 1.25

01446400 Yes 40 0 0 n.a. 0.66 1 1.13 1.28 1.5

01457400 Yes 40 0 0 n.a. 0.36 1.68 2.09 2.49 3.34

01457500 Yes 40 0 0 n.a. 0.48 0.82 0.96 1.14 1.6

01458570 Yes 40 0 0 n.a. 0.24 1.37 1.92 2.4 3.09

01461000 Yes 38 0 0 n.a. 0.56 0.8 0.93 1.08 1.4

01463500 Yes 39 0 0 n.a. 0.47 0.66 0.84 0.98 1.3

01463850 Yes 40 0 0 n.a. E 0.03 0.79 1.06 1.43 3.46

01464020 Yes 40 0 0 n.a. 1.23 2.82 4.06 5.78 9.77

Lower Delaware Water Region

01411466 Yes 39 0 0 n.a. 0.15 0.35 0.52 0.61 0.72

01411500 Yes 34 0 0 n.a. 0.35 1.45 1.67 1.86 2.45

01411955 Yes 40 1 3 0.01 < 0.01 0.08 0.11 0.13 0.23

01412800 Yes 40 0 0 n.a. 2.5 4.4 4.89 5.47 7

01464504 Yes 39 0 0 n.a. 0.36 0.52 0.7 0.86 1.32

01464515 Yes 40 0 0 n.a. 0.4 0.55 0.8 1.16 1.91

01465893 Yes 39 8 21 0.05 < 0.02 0.04 0.07 0.11 0.29

01466500 No 40 34 85 0.05 < 0.01 n.d. n.d. n.d. 0.1

01467005 Yes 40 0 0 n.a. 0.1 0.21 0.25 0.31 0.91

01467150 Yes 40 0 0 n.a. 0.12 0.2 0.29 0.34 0.48

01467359 Yes 40 0 0 n.a. 0.26 0.42 0.5 0.67 1.13

01477120 Yes 40 0 0 n.a. 0.59 1.01 1.22 1.62 3.28

01482500 Yes 40 1 3 0.03 < 0.03 0.53 1.97 2.76 5.45
Table 15 69

Table 15. Results of trend tests on flow-adjusted concentrations of dissolved nitrate plus nitrite at water-quality stations on New 

Jersey streams, water years 1998–2007.—Continued

[ --, no trend in flow-adjusted concentrations of dissolved nitrate plus nitrite during the period of study was identified at a 0.05 level of significance; Decrease, 

dissolved nitrate plus nitrite decreased during the period of study; Increase, dissolved nitrate plus nitrite increased during the period of study; n.d., not determined] 

Station 

number

Whether a single 

outlying point was 

dropped from test

Results of Tobit regression trend tests on flow-adjusted concentrations of dissolved nitrate plus nitrite

Summary 

result

Trend slope

Level of 

significance 

In milligrams per liter 

as N per year

In percent of mean value per year (mean 

value in milligrams per liter as N)

Passaic Water Region

01377000 No -- 0.207 0.010 2.1 (0.47)

01378560 No -- 0.715 0.013 1.2 (1.1)

01378780 No -- 0.300 0.009 2.6 (0.33)

01379200 No Decrease 0.001 -0.256 -6.7 (3.8)

01380100 Yes Increase 0.043 0.009 5.2 (0.18)

01381800 No -- 0.496 -0.020 -1.0 (1.9)

01382000 No -- 0.101 -0.063 -2.4 (2.6)

01382500 No -- 0.485 -0.004 -1.7 (0.22)

01387500 No -- 0.951 0.001 0.1 (1.6)

01388500 No Increase 0.009 0.037 4.2 (0.9)

01389500 No -- 0.879 0.005 0.2 (2.3)

01391500 Yes Increase 0.044 0.117 2.2 (5.2)

Raritan Water Region

01394500 No -- 0.285 -0.018 -1.4 (1.3)

01395000 Yes -- 0.131 0.028 2.7 (1)

01396660 No Increase 0.035 0.021 2.5 (0.84)

01398000 No -- 0.768 -0.016 -1.4 (1.1)

01398102 No -- 0.913 -0.003 -0.2 (1.4)

01399780 No -- 0.140 0.044 5.0 (0.89)

01400000 No Increase 0.003 0.053 5.9 (0.91)

01400640 No -- 0.050 0.121 3.0 (4)

01401400 No -- 0.523 0.020 0.7 (2.7)

01402000 No -- 0.322 0.026 1.0 (2.7)

01403385 No -- 0.431 0.026 3.0 (0.86)

01405340 No Increase 0.007 0.026 3.0 (0.87)

Atlantic Coastal Water Region

01408000 Yes -- 0.151 0.008 1.8 (0.44)

01408009 No -- 0.497 -0.001 -2.6 (0.046)

01408100 No Increase 0.000 0.041 8.0 (0.51)

01408500 No Increase 0.010 0.018 3.1 (0.6)

01408830 n.d. n.d. n.d. n.d. n.d. (n.d.)

01409387 No -- 0.231 0.003 3.1 (0.087)

0140940950 No -- 0.202 0.017 6.6 (0.25)

01409416 No Increase 0.015 0.059 4.3 (1.4)

01409500 No Increase 0.013 0.011 6.9 (0.16)

01409815 n.d. n.d. n.d. n.d. n.d. (n.d.)

01410150 n.d. n.d. n.d. n.d. n.d. (n.d.)

01411035 No Decrease 0.001 -0.033 -3.2 (1)

01411110 Yes Increase 0.000 0.020 4.3 (0.48)

01411196 No Increase 0.019 0.012 2.4 (0.51)

01411400 No -- 0.220 -0.006 -6.7 (0.096)

01411444 No -- 0.627 0.002 2.8 (0.059)
70 Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007

Table 15. Results of trend tests on flow-adjusted concentrations of dissolved nitrate plus nitrite at water-quality stations on New 

Jersey streams, water years 1998–2007.—Continued

[ --, no trend in flow-adjusted concentrations of dissolved nitrate plus nitrite during the period of study was identified at a 0.05 level of significance; Decrease, 

dissolved nitrate plus nitrite decreased during the period of study; Increase, dissolved nitrate plus nitrite increased during the period of study; n.d., not determined] 

Station 

number

Whether a single 

outlying point was 

dropped from test

Results of Tobit regression trend tests on flow-adjusted concentrations of dissolved nitrate plus nitrite

Summary 

result

Trend slope

Level of 

significance 

In milligrams per liter 

as N per year

In percent of mean value per year (mean 

value in milligrams per liter as N)

Upper Delaware Water Region

01367625 No -- 0.207 0.010 1.7 (0.57)

01367770 Yes Decrease 0.035 -0.053 -3.4 (1.6)

01367800 No -- 0.816 -0.005 -0.6 (0.92)

01368820 No -- 0.582 -0.002 -2.6 (0.062)

01438500 Yes -- 0.068 -0.008 -3.6 (0.23)

01440000 No -- 0.107 0.005 5.3 (0.09)

01442760 No -- 0.292 0.010 9.5 (0.1)

01443000 No -- 0.897 0.001 0.4 (0.21)

01443500 No -- 0.471 0.012 2.1 (0.54)

01446400 No -- 0.447 0.008 0.7 (1.1)

01457400 No Increase 0.000 0.078 3.8 (2.1)

01457500 No -- 0.278 0.014 1.5 (0.97)

01458570 No -- 0.096 0.051 2.7 (1.9)

01461000 No -- 0.649 0.005 0.5 (0.94)

01463500 No -- 0.876 0.002 0.2 (0.84)

01463850 No -- 0.979 0.001 0.1 (1.1)

01464020 No -- 0.861 0.006 0.1 (4.3)

Lower Delaware Water Region

01411466 Yes Increase 0.005 0.019 3.9 (0.5)

01411500 Yes Increase 0.006 0.048 3.0 (1.6)

01411955 No -- 0.836 0.001 0.5 (0.11)

01412800 No Increase 0.002 0.164 3.4 (4.9)

01464504 No Increase 0.018 0.026 3.7 (0.7)

01464515 No -- 0.908 0.002 0.2 (0.92)

01465893 No -- 0.320 0.004 4.2 (0.086)

01466500 n.d. n.d. n.d. n.d. n.d. (n.d.)

01467005 Yes Decrease 0.037 -0.009 -3.1 (0.28)

01467150 No Increase 0.032 0.012 4.0 (0.29)

01467359 No Increase 0.000 0.023 4.2 (0.55)

01477120 No -- 0.532 0.014 1.0 (1.3)

01482500 No -- 0.885 0.013 0.7 (1.9)
For additional information, write to:

Director

U.S. Geological Survey

New Jersey Water Science Center

810 Bear Tavern Road, Suite 206

West Trenton, NJ 08628

or visit our Web site at:

http://nj.usgs.gov/

Document prepared by the West Trenton Publishing Service Center
Hickman and Gray—Trends in the Quality of Water in New Jersey Streams, Water Years 1998–2007—Scientific Investigations Report 2010–5088