U.S. Department of the Interior

U.S. Geological Survey

WATER QUALITY OF THE DELAWARE AND RARITAN 

CANAL, NEW JERSEY, 1998-99

Water-Resources Investigations Report 01-4072

Prepared in cooperation with the

NEW JERSEY WATER SUPPLY AUTHORITY
WATER QUALITY OF THE DELAWARE AND RARITAN 

CANAL, NEW JERSEY, 1998-99

By Jacob Gibs, Bonnie Gray, Donald E. Rice, Steven Tessler, and Thomas H. 

Barringer

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 01-4072

Prepared in cooperation with the

NEW JERSEY WATER SUPPLY AUTHORITY

West Trenton, New Jersey

2001
U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

The use of firm, trade, and brand names in this report is for identification purposes only 

and does not constitute endorsement by the U.S. Government.

For additional information Copies of this report can be

write to: purchased from:

District Chief

U.S. Geological Survey U.S. Geological Survey

Mountain View Office Park Branch of Information Services

810 Bear Tavern Road, Suite 206 Box 25286

West Trenton, NJ 08628 Denver, CO 80225-0286
 iii

CONTENTS

Page

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

Introduction....................................................................................................................................2

Purpose and scope .................................................................................................................2

Approach ...............................................................................................................................3

Previous studies .....................................................................................................................3

Acknowledgments .................................................................................................................4

Description of study area ..............................................................................................................4

Delaware and Raritan Canal..................................................................................................5

Drainage basins influent to the Delaware and Raritan Canal................................................5

Methods of investigation .............................................................................................................10

Site selection........................................................................................................................10

Continuous-monitoring sites ....................................................................................... 11

Instantaneous water-quality sample-collection sites ................................................... 11

Water-quality sampling .......................................................................................................12

Water-quality monitoring ....................................................................................................12

Continuous on-site measurements...............................................................................12

Turbidity..............................................................................................................13

Specific conductance ..........................................................................................13

Temperature ........................................................................................................13

Calibration procedures ...............................................................................................13

Turbidity..............................................................................................................13

Specific conductance ..........................................................................................14

Temperature ........................................................................................................14

Instantaneous water-column water-quality sampling..................................................14

Sample collection................................................................................................14

Sample processing ..............................................................................................14

Laboratory and field analyses .....................................................................................15

Total suspended solids ........................................................................................15

Whole-water and filtered nitrogen species .........................................................15

Whole-water and filtered phosphorous...............................................................15

Dissolved and suspended organic carbon ...........................................................15

Specific conductance ..........................................................................................15

Ultraviolet absorbance at 254 nanometers..........................................................16

Volatile organic compounds................................................................................16

Turbidity..............................................................................................................16

Data analysis........................................................................................................................16

Continuous water-quality data ....................................................................................16

Data preparation..................................................................................................16

Analysis of the change in water quality in a reach .............................................17

Instantaneous-water-quality data.................................................................................17

Relational database..............................................................................................................18

Geographical information system........................................................................................18
iv

CONTENTS--Continued

Page

Water quality of the Delaware and Raritan Canal .......................................................................18

Samples collected during storm and nonstorm events ........................................................18

Continuous water-quality monitoring..................................................................................29

Specific conductance...................................................................................................30

Turbidity......................................................................................................................32

Summary......................................................................................................................................35

References cited...........................................................................................................................38

Appendix A. Relational database design .....................................................................................40

ILLUSTRATIONS

Figures 1-4.Maps showing:

1. Locations of water-quality sampling sites and influent drainage basins along

the Delaware and Raritan Canal, New Jersey.....................................................6

2. Land use in Duck Pond Run drainage basin, New Jersey, in 1986 and 1996,

based on Integrated terrain land use (ITU), as interpretted from U.S.

Geological Survey 1996 digital infrared orthophoto ..........................................7

3. Land use within the Als Brook drainage basin and hydrologic infalls to the

Delaware and Raritan Canal, Somerset County, New Jersey .............................8

4. Drainage basins influent to the feeder section of the Delaware and Raritan 

Canal and 1986 integrated terrain land use (ITU), Hunterdon and Mercer

Counties, New Jersey..........................................................................................9

Figures 5-18 Boxplots showing:

5. Distributions of concentrations of suspended organic carbon in samples 

collected during storms and nonstorm conditions at sites on the Delaware

and Raritan Canal, N.J., 1998-99......................................................................20

6. Distribution of concentrations of ammonia plus organic nitrogen in filtered 

samples collected during storms and nonstorm conditions from the Delaware

and Raritan Canal, N.J., and the Delaware River at Lumberville, Pa..............22

7. Distribution of concentrations of dissolved organic carbon in samples 

collected during storms and nonstorm conditions from the Delaware and 

Raritan Canal, N.J., and the Delaware River at Lumberville, Pa. ....................22

8. Distribution of ultraviolet absorbance at 254 nanometers in filtered samples

collected during storms and nonstorm conditions from the Delaware and

Raritan Canal, N.J., and the Delaware River at Lumberville, Pa. ....................23

9. Distribution of concentrations of nitrate plus nitrite nitrogen in filtered 

samples collected during storms and nonstorm conditions from the 

Delaware and Raritan Canal, N.J., and the Delaware River at Lumberville,

Pa. .....................................................................................................................23

10. Distribution of concentrations of phosphorous in filtered samples collected 

during storms and nonstorm conditions from the Delaware and Raritan 

Canal, N.J..........................................................................................................24
v

ILLUSTRATIONS--Continued

Page

Figure 11. Distribution of concentrations of total phosphorous in samples collected 

during storms and nonstorm conditions from the Delaware and Raritan 

Canal, N.J., and the Delaware River at Lumberville, Pa. .................................24

12. Distribution of field turbidity in samples collected during storms and 

nonstorm conditions from the Delaware and Raritan Canal, N.J. ....................25

13. Distribution of concentrations of total ammonia plus organic nitrogen in 

samples collected during storms and nonstorm conditions from the 

Delaware and Raritan Canal, N.J., and the Delaware River at Lumberville, 

Pa. .....................................................................................................................25

14. Distribution of specific conductance in samples collected during storms and 

nonstorm conditions from the Delaware and Raritan Canal, N.J., and the 

Delaware River at Lumberville, Pa...................................................................26

15. Distribution of concentrations of suspended organic carbon in samples 

collected during storms and nonstorm conditions from the Delaware and 

Raritan Canal, N.J., and the Delaware River at Lumberville, Pa. ....................26

16. Distribution of concentrations of methyl tert-butyl ether in samples collected 

during storms and nonstorm conditions from the Delaware and Raritan 

Canal, N.J..........................................................................................................27

17. Distribution of concentrations of total suspended solids in samples collected 

during storms and nonstorm conditions from the Delaware and Raritan 

Canal, N.J., and the Delaware River at Lumberville, Pa. .................................27

18. Distribution of concentrations of methyl tert-butyl ether in samples collected 

from the Delaware River at Trenton, N.J. during water years 1995-99 and 

the Delaware and Raritan Canal, N.J., during water years 1998-99.................29

19-22. Graphs showing:

19. Minimum, maximum, and mean of continuously monitored specific conductance 

at six sampling locations along the length of the Delaware and Raritan Canal, 

N.J., February 1998 to May 1999 .....................................................................30

20. Mean and median of the travel-time lagged net changes in specific conductance 

in the five reaches of the Delaware and Raritan Canal, N.J., February 1998 

to May 1999 ......................................................................................................31

21. Minimum, maximum, and mean of continuously monitored turbidity at six 

sampling locations along the length of the Delaware and Raritan Canal, 

N.J., February 1998 to May 1999 .....................................................................33

22. Mean and median of the travel-time lagged net changes in turbidity in the 

five reaches of the Delaware and Raritan Canal, N.J., February 1998

to May 1999 ......................................................................................................34
vi

TABLES

Page

Table 1. Maximum, median, and minimum concentrations of nitrite and ammonia in 

storm and nonstorm samples from all sampling sites on the Delaware and 

Raritan Canal, N.J..................................................................................................19

2. Results of the Kruskal-Wallis test on median values of constituents in storm 

and nonstorm samples from all sampling sites on the Delaware and 

Raritan Canal, N.J..................................................................................................28
vii

CONVERSION FACTORS, VERTICAL DATUM, AND

ABBREVIATED WATER-QUALITY UNITS

Multiply By To obtain

Length

inch (in.) 25.4 millimeter

inch (in.) 2.54 centimeter

foot (ft) 0.3048 meter

mile (mi) 1.609 kilometer

Area

acre 4,047 square meter

acre 0.4047 hectare

square foot (ft2) 929.0 square centimeter

square foot (ft2) 0.09294 square meter

square mile (mi2) 259.0 hectare

square mile (mi2) 2.590 square kilometer

Volume

gallon (gal) 3.785 liter

gallon (gal) 0.003785 cubic meter

cubic foot (ft3) 0.02832 cubic meter

Flow

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

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

cubic foot per minute (ft3/min) 0.02832 cubic meter per minute

(m3/min)

mile per hour (mi/h) 1.609 kilometer per hour

gallon per minute (gal/min) 0.06308 liter per second

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

Temperature

degree Fahrenheit (°F) °C = 5/9 x (°F-32) degree Celsius (°C)
viii

CONVERSION FACTORS, VERTICAL DATUM, AND

ABBREVIATED WATER-QUALITY UNITS--Continued

Vertical datum: In this report “sea level” refers to the National Geodetic Vertical Datum of 1929-- a 

geodetic datum derived from a general adjustment of the first-order level nets of the United States and 

Canada, formerly called Sea Level Datum of 1929.

Water-quality abbreviations:

μg -micrograms DOC -dissolved organic carbon

mg -milligrams SOC -suspended organic carbon

mg/L -milligrams per liter POC -purgeable organic compound

μg/L -micrograms per liter TOC -total organic carbon

μS/cm -microsiemens per centimeter at VOC -volatile organic compound

 25 degrees Celsius
1

Water Quality of the Delaware and Raritan Canal, New Jersey, 1998-

1999 

By Jacob Gibs, Bonnie Gray, Donald E. Rice, Steven Tessler,

and Thomas H. Barringer

ABSTRACT

Since 1934, the Delaware and Raritan 

Canal has been used to transfer water from the 

Delaware River Basin to the Raritan River 

Basin. The water transported by the Delaware 

and Raritan Canal in New Jersey is used 

primarily for public supply after it has been 

treated at drinking-water treatment plants 

located in the Raritan River Basin. Recently 

(1999), the raw water taken from the canal 

during storms has required increased amounts 

of chemical treatments for removal of 

suspended solids, and the costs of removing 

the additional sludge or residuals generated 

during water treatment have increased. At 

present, action to control algae is unnecessary.

The water quality of the Delaware and 

Raritan Canal was studied for approximately 

16.5 months from mid-January 1998 through 

May 1999 to determine whether changes in 

water quality along the length of the canal are 

associated with storms. Nine water-quality 

constituents, and field measured specific 

conductance and turbidity were statistically 

tested.

Instantaneous or grab samples of water 

were collected from the Delaware and Raritan 

Canal after five storms and during four 

nonstorm events. Median values of waterquality constituents in samples collected 

immediately after storms and during nonstorm 

conditions when statistically compared by 

sampling location were not significantly 

different. Therefore, the data were combined 

or aggregated to eliminate one of the two 

explanatory variables, either individual 

sampling sites or the two types of sampling 

events, in order to generate a sample 

population large enough to show statistically 

significant differences. After combining 

sampling events, only the median 

concentration of suspended organic carbon, 

and field measured specific conductance and 

turbidity, were significantly different among 

sampling sites. Median concentrations of total 

and filtered ammonia plus organic nitrogen, 

total phosphorous, turbidity, ultraviolet 

absorbance at 254 nanometers, and dissolved 

organic carbon in samples collected after 

storms were significantly greater than in 

samples collected during nonstorm conditions, 

when the sampling locations were aggregated 

in the statistical analysis. Methyl tert-butyl 

ether, the most frequently detected volatile 

organic compound (VOC), was detected in 55 

of 80 samples. The highest concentration of 

methyl tert-butyl ether, 3.2 micrograms per 

liter, was measured in a sample collected 

during nonstorm conditions.

The median of the continuously 

monitored specific conductance during 

nonstorm conditions at Port Mercer, N.J., 

increased by approximately 3 to 4 μS/cm 

(microsiemens per centimeter) (1.5 to 2 

percent of the median specific conductance) 

relative to that at the nearest upstream site, at 

Lower Ferry Road. The land use in the 

influent basins for this reach of the Delaware 

and Raritan Canal is primarily urban. One 

possible source of water with high specific 

conductance is either domestic or industrial 

wastewater that continuously discharges into 

pipes, then empties into the canal. Another 

possible source is ground water from an area 

within this reach where the elevation of the 

water table is higher than that of the water 

surface of the Delaware and Raritan Canal.

 The median continuously monitored 

specific conductance measured during 

nonstorm conditions at the Route 18 Spillway 

site increased relative to that of the nearest 

upstream site, Ten Mile Lock, by 

approximately 3 to 4 μS/cm. The mean net 

change in continuously monitored specific 

conductance for this reach during storms also 

increased. Land use in the two largest influent 
2

basins within this reach, the Borough of South 

Bound Brook and Als Brook, is predominantly 

urban.

The mean and median of continuously 

monitored turbidity varied along the length of 

the canal. In the reach between Raven Rock 

and Lower Ferry Road, the mean and median 

for continuously monitored turbidity during 

the study period increased by 7.2 and 6.2 NTU 

(nephelometric turbidity units), respectively. 

The mean of continuously monitored turbidity 

decreased downstream from Lower Ferry 

Road to Ten Mile Lock. Turbidity could 

increase locally downstream from influent 

streams or outfalls, but because the average 

velocity of water in the canal is low, particles 

that cause turbidity are not transported 

appreciable distances. In the reach between 

Ten Mile Lock and the Route 18 Spillway, the 

mean and median of the continuously 

monitored turbidity changed less than 

0.5 NTU during the period of record. The 

small change in turbidity in this reach is not 

consistent with an average velocity for the 

reach; the average velocity in this reach was 

the lowest in all of the reaches studied. The 

expected decrease in turbidity due to settling 

of suspended solids is likely offset by turbid 

water entering the canal from influent streams 

or discharges from storm drains. Field 

observation of a sand bar immediately 

downstream from the confluence of Als Brook 

and the canal confirmed that the Als Brook 

drainage basin has contributed stormwatergenerated sediment to the canal that could 

reach the monitor located at the Route 18 

Spillway and the raw water intakes for two 

drinking-water treatment plants.

INTRODUCTION

The Delaware and Raritan Canal, 

which was put into operation in 1834, was 

originally constructed as a barge canal. In 

1934, the State of New Jersey acquired the 

canal, and it is currently operated by the New 

Jersey Water Supply Authority (NJWSA). 

Since 1934, the canal has been used for 

interbasin transfer of water from the Delaware 

River Basin to the Raritan River Basin. Water 

purveyors, who are customers of the NJWSA, 

use the canal as a source of raw water that will 

be treated and distributed as public drinking 

water.

Since 1997, several water purveyors 

have noticed that the raw water withdrawn 

from the canal during precipitation events has 

required increased amounts of chemicals for 

the removal of suspended solids which, in 

turn, generates increased amounts of sludge or 

residuals. The increased use of chemicals in 

treating the water and removing additional 

sludge or residuals contributes to the increased 

cost of producing drinking water that meets 

the desired chemical quality and regulatory 

standards. Drinking-water purveyors are 

concerned that this worsening of water quality 

during storms could be part of a long-term 

trend of declining water quality and want to 

determine the possible sources or causes. To 

address these concerns, the U.S. Geological 

Survey (USGS), in cooperation with the New 

Jersey Water Supply Authority, conducted a 

study from mid-Janury 1998 through May 

1999 to determine whether the water quality in 

the canal is affected by stormwater runoff 

from basins influent to the canal, and if so, to 

identify which of the canal reaches are the 

largest sources of the poorer water quality that 

the drinking-water-treatment plants are 

treating during storms. In order to effectively 

manage the logistics of conducting sampling 

along the 58-mile long canal during a storm, 

the collection of surface-water samples and 

analysis of water-quality data were divided 

into two projects. The first project, a 

reconnaissance of the entire length of the 

canal is designed to evaluate changes, 

statistically and qualitatively, in the quality of 

water at the ends of reaches of 10 miles or 

longer. The second project, which has not 

been conducted as of the publication of this 

report, will consist of collecting and 

analyzing samples from individual influent 

streams or pipes that discharge into the canal 

in those reaches of the canal where significant 

changes in water quality have occurred.

Purpose and Scope

This report describes the first project 

in a two-part study and characterizes the water 

quality of the Delaware and Raritan Canal 
3

over a period of approximately 16.5 months 

(mid-January 1998 through May 1999). Water 

samples were collected and analyzed to 

determine changes in the water quality of the 

canal associated with storms, and to compare 

the water quality related to storms to that of 

periods when no precipitation occurred, along 

the length of the canal.

Six continuous water-quality monitors 

were used to collect data along almost the 

entire length of the canal. Specific 

conductance, temperature, and turbidity were 

the water-quality characteristics that were 

continuously monitored.

Instantaneous water samples were 

collected at seven locations after the start of 

five storms and four times when there was no 

precipitation. The instantaneous water-quality 

samples were analyzed for nitrogen species 

(nitrite, nitrite plus nitrate, ammonia, and 

ammonia plus organic nitrogen in filtered 

samples, and ammonia plus organic nitrogen 

in whole water samples), phosphorous in 

filtered and unfiltered samples, total 

suspended solids, suspended organic carbon, 

dissolved organic carbon, ultraviolet 

absorbtion at 254 nanometers (UV 254), and 

29 volatile organic compounds (VOCs). 

Specific conductance and turbidity were 

measured in the field. Results of these 

analyses and measurements are presented in 

tables and figures.

 In addition, water-quality data 

obtained during the study were organized and 

formatted into a relational database. 

Geographic information system (GIS) files 

were created to represent the canal and 

cultural features associated with the canal, and 

land uses of the drainage basins influent to the 

canal.

Approach

The changes in the water quality along 

the length of the canal caused by stormwater 

runoff and continuous discharges to the canal 

from unknown sources, and the biological, 

chemical, and physical processes that occur in 

the canal, were evaluated by measuring 

constituents in instantaneous water samples 

collected at seven locations along the canal 

where width- and depth-integrated samples 

could be obtained. Instantaneous water-quality 

samples were collected after the start of five 

storms (after 0.5 inch of precipitation had 

fallen) and on four occasions when there had 

been no precipitation for the previous ten days 

(hereafter called a nonstorm event or 

condition). Continuous measurements of 

temperature, specific conductance, and 

turbidity were collected at six sites, at five of 

which instantaneous water samples also were 

collected. This arrangement of continuous 

water-quality monitoring locations divided the 

length of the canal into five reaches. The 

change in water quality along the length of the 

canal was determined by sampling at each 

instantaneous water-quality sampling site and 

subsequent analysis of the samples at the 

USGS National Water Quality Laboratory 

(NWQL) or the USGS New Jersey District 

laboratory, or by continuously measuring the 

changes in water quality in each reach at the 

continuous water-quality monitoring sites and 

subsequent evaluation of that data.

Previous Studies

The hydrology of watersheds flowing 

into and under the canal has been studied by 

Ebasco Services, Inc. (1988). Watersheds and 

watershed divides adjacent to the feeder part 

of the canal, which extends from the canal 

inlet on the Delaware River to Southard Street 

in the City of Trenton, N.J., are described in 

the report, and the watersheds that drain into 

or under the feeder part of the canal are 

identified. Maps containing information on 

influent basins to the feeder part of the canal 

were incorporated into geographic information 

system coverages generated in this study.

The plans and goals for the 

establishment and maintenance of a state park 

encompassing the canal and for a naturalresource inventory of the state park are 

contained in a report by the Delaware and 

Raritan Canal Commission (1977). Streams 

that flow into or under the canal, the drainage 

basins of those streams that flow into or under 

the canal, and areas of local runoff or overland 

flow that reach the canal were identified in the 

natural-resource inventory of the report.
4

Rutgers University (1980) conducted a 

study of the hydrologic, hydraulic, waterquality, and operational characteristics of the 

canal. The discussion of water quality is a 

snapshot of the water quality for 1974 through 

1977. The Rutgers University report also 

contains a list of structures and their locations 

on canal property. This list was incorporated 

into geographic information system coverages 

generated for the present study.

Camp, Dresser, and McKee, 

Inc.(1986) evaluated seven ways to divert 

stormwater that flows into the U.S. Route 1 

conduit of the canal to the Assunpink Creek. 

The diversion of stormwater to the Assunpink 

Creek would reduce the cost of repeated 

dredging to maintain the flow capacity of the 

conduit. The proposed alternatives were not 

adopted (Steven Nieswand, U.S. Geological 

Survey, oral commun., 1999). Camp, Dresser, 

and McKee, Inc. (1986) delineated the 

drainage areas from which stormwater 

originates, then flows into the canal and the 

U.S. Route 1 conduit. The spatial information 

on stormwater drainage basins that discharge 

into the conduit was incorporated into 

geographic information system coverages 

generated in the present study. Results of 

chemical analyses of sediment collected from 

seven storm drains that empty into the conduit 

for trace elements, polychlorinated biphenyls, 

and chlorinated pesticides also are reported.

NJWSA has no historical 

documentation or reports that conclude waterquality degradation associated with excessive 

algal growth occurred in canal water, and 

none of the water purveyors has complained to 

the NJWSA about the taste or odor of treated 

drinking water that might be attributable to 

algae in canal water (Edward Buss, New 

Jersey Water Supply Authority, written and 

oral commun., 1999).

Hickman and Barringer (1999) and 

Hay and Campbell (1990) discuss waterquality changes at the Delaware River at 

Lumberville, Pa. (USGS surface water-quality 

station 01461000) during 1986-95 and

1976-86, respectively. The Delaware River at 

Lumberville drains an area of 6,598 mi2; 

water quality at this station can be used to 

represent the water quality at the intake of the 

canal on the Delaware River because this 

station is located approximately 0.7 miles 

downstream from the intake. Within the 

0.7 miles, there is a negligible increase in the 

drainage area of the Delaware River. Thus, 

very little change in the water quality would 

be expected to occur within this reach. Hay 

and Campbell (1990) evaluated 22 

constituents for trends at the Delaware River 

at Lumberville, Pa. The results of their 

analysis (at a statistical confidence level of 

95 percent or greater) indicated that 

concentrations of total organic carbon 

decreased and pH increased during 1975-86, 

and that concentrations of sulfate decreased 

during 1979-86. Hickman and Barringer 

(1999) evaluated trends for 23 water-quality 

constituents. The results of their analyses (at a 

statistical confidence level of 95 percent or 

greater) indicated that biochemical oxygen 

demand increased, and total nitrogen, total 

ammonia nitrogen, organic plus ammonia 

nitrogen, total organic carbon, and fecal 

coliform (MPN) decreased during 1986-95.

Acknowledgments

The authors thank John Petersen, John 

Gallucci, Paul Luhrman, Michael Anderson, 

and Leonard Navarro of the NJWSA for 

collecting all the instantaneous water samples 

during storms. The authors also thank the 

NJWSA personnel, in particular Edward Buss 

and Joseph Sheppard, for providing reports 

and information about canal operations and 

design, which helped make this project report 

possible.

DESCRIPTION OF STUDY AREA

The study area consists of the 

Delaware and Raritan Canal and all drainage 

basins influent to the canal (fig. 1). The study 

area lies almost wholly within the Piedmont 

Physiographic Province in New Jersey. A 

small part of the area, part of the Duck Pond 

Run influent drainage basin, is in the Coastal 

Plain Physiographic Province.

Average annual precipitation in the 

study area ranges from 42 to 46 inches. The 

average annual runoff ranges from 21 to 

23 inches (Schopp and Bauersfeld, 1985).
5

Delaware and Raritan Canal

The Delaware and Raritan Canal is 

approximately 58 miles long from the water 

intake on the Delaware River, 0.7 miles 

upstream from Raven Rock, to the end of the 

canal at the Route 18 Spillway, which empties 

canal water into the Raritan River at New 

Brunswick (fig. 1). The canal is entirely 

within the Piedmont Physiographic Province 

in New Jersey (Otto S. Zapecza, U.S. 

Geological Survey, oral commun., 1999).

The canal is roughly parallel to the 

Delaware River from the inlet on the 

Delaware River to Calhoun Street in Trenton, 

a distance of 21.8 miles. At Calhoun Street, 

the canal turns to the northeast, away from the 

Delaware River, and is roughly parallel to the 

Fall Line, the dividing line between the 

Piedmont and Coastal Plain Physiographic 

Provinces. Near Southard Street in Trenton, 

the canal goes underneath U.S. Route 1 in two 

identical 13 feet by 8 feet reinforced concrete 

rectangular conduits that extend 

approximately 1.15 miles to Mulberry Street 

in Trenton (Camp, Dresser, and McKee, Inc., 

1986). The canal becomes an open channel 

again downstream from Mulberry Street and 

runs approximately parallel to U.S. Route 1 

from Trenton City to the aqueduct over the 

Millstone River. After crossing the Millstone 

River, the canal follows the right bank (in the 

downstream direction) of the Millstone River 

until it reaches the confluence of the Millstone 

and Raritan Rivers. The canal then follows the 

Raritan River along the right bank and ends at 

the Route 18 Spillway in New Brunswick.

In 2000, there are eight historically 

certified locks on the Canal. These eight locks 

have been modified; the lock gates have been 

replaced with weirs and sluice gates that 

control the water level or, in the case of the 

Raven Rock lock, with a set of sluice gates 

only. Supplemental overflow weirs have been 

installed at five locks--Griggstown, Ten Mile, 

South Bound Brook, Five Mile (Rutgers 

University, 1980) and Kingston (John 

Petersen, New Jersey Water Supply Authority, 

oral commun., 1999).

The aqueduct that carries canal water 

over the Millstone River has a series of sluice 

gates to allow diversion of Millstone River 

water into the canal during periods of flooding 

in the Millstone River to maintain the 

structural stability of the aqueduct (Rutgers 

University, 1980) or to provide additional 

water to the canal during droughts in the 

Delaware River Basin.

Drainage Basins Influent to the 

Delaware and Raritan Canal

The total area of basins draining into 

the canal (hereafter called influent drainage 

basins) is 53,860 acres. The four largest 

influent drainage basins, which account for 

76.2 percent of the total area of all the influent 

drainage basins, in descending order of 

drainage area, are Wickecheoke Creek (16,987 

acres), Lockatong Creek (14,815 acres), Duck 

Pond Run (3,904 acres), and Als Brook 

(2,411acres), (Delaware and Raritan Canal 

Commission, 1977). Duck Pond Run flows 

into the canal between Port Mercer and 

Griggstown (fig. 1). Land use in the Duck 

Pond Run Basin is undergoing rapid change 

from agricultural to urban (fig. 2). The Als 

Brook Basin drains into the canal between Ten 

Mile Lock and Landing Lane Bridge about 

1.5 miles from the Route 18 Spillway (fig. 3). 

The Als Run drainage basin contains a 

mixture of land uses, (urban, 48.1 percent; 

agriculture, 3 percent; and undeveloped, 

48 percent) which was determined from the 

1986 integrated terrain land use (ITU) 

coverage, (New Jersey Department of 

Environmental Protection, 1996). The 

Wickecheoke Creek and the Lockatong Creek 

Basins drain into the feeder part of the canal 

between the Raven Rock feed gates and 

Brookville (fig. 4). The predominant land use 

in the Wickecheoke Creek and the Lockatong 

Creek Basins is agricultural (60 percent of the 

total area of the two basins) (fig. 4).

METHODS OF INVESTIGATION

Eight sites were selected at locations 

along the canal, from the inlet on the 

Delaware River at Bull’s Island, N.J. (fig. 4), 

to the outlet at the Raritan River near 
6

Raritan

River

Millstone

R

vi er

Millstone River

Project area

0 5 10 MILES

0 5 10 KILOMETERS

40

30’

75

40

15’

74 30’

Hunterdon County

Somerset County

Middlesex County

Mercer County

Ten Mile Lock

Route 18

 Spillway

Landing Lane 

Bridge

Griggstown

Port Mercer

Lower Ferry Road

Brookville

Raven Rock

NEW JERSEY

New

Jersey

FALL LINE

Figure 1. Locations of water-quality sampling sites and influent drainage basins along the 

Delaware and Raritan Canal, New Jersey.

Lockatong Creek and Wickecheoke

Creek Basins

Als Brook Basin

Duck Pond Run Basin

Main canal

Feeder canal

Influent drainage basins

Sampling location

Delaware and Raritan Canal

EXPLANATION

PENNSYLVANIA

Delaware

River

New Brunswick

Trenton COASTAL PLAIN

PIEDMONT

South Bound Brook Basin

Manville

Southard 

Street

Route 1

Calhoun 

Street 

Princeton 

Avenue

Inset map

Inset map of Trenton City

in the vicinity of the

Delaware and Raritan Canal

Mulberry 

Street

Delaware and Raritan Canal
7

0 2,000 4,000 6,000 FEET

40 17'30"

74 37'30"

74 40'

40 18'

40 18'30"

0 1,000 METERS

Urban area in 1986

Nonurban (includes both agricultural

and undeveloped land uses), 1986

Urban area in 1996 that was nonurban 

in 1986

ITU land use

Delaware and Raritan Canal

Duck Pond Run

EXPLANATION

Figure 2. Land use in the Duck Pond Run drainage basin, New Jersey, in 1986 and 1996, based on 

Integrated terrain land use (ITU), as interpreted from U.S. Geological Survey 1996 digital infrared 

orthophoto.

Percent of total

28.6

71.4

19.7

Project area

0 5 10 MILES

0 5 10 KILOMETERS

40

30'

75

40

15'

74 30'

Hunterdon County

Somerset County

Middlesex County

Mercer County

Duck Pond Run

PENNSYLVANIA

NEW JERSEY

New

Jersey
8

0 2,000 4,000 6,000 FEET

0 1,000 METERS

74 30’

74 34’

40

30’

40

32’

Urban

Agricultural

Undeveloped

Influent stream

Delaware and Raritan Canal

River

Influent drainage basin

Sampling location

Infalls, field verified

EXPLANATION

Digital orthophoto quadrangle land use, 

Als Brook Basin, 1986

Figure 3. Land use within the Als Brook drainage basin and hydrologic infalls to the

Delaware and Raritan Canal, Somerset County, New Jersey.

Ten Mile 

Lock

Route 18

Spillway

Landing Lane Bridge

Percent of total

48.1

3.9

48

Project area

0 5 10 MILES

0 5 10 KILOMETERS

40

30’

75

40

15’

74 30’

Hunterdon County

Somerset County

Middlesex County

Mercer County

Ten Mile Lock Route 18 spillway

Als Brook

Basin

PENNSYLVANIA

NEW JERSEY

New 

Jersey
9

Bulls Island

0 5 MILES

0 5 KILOMETERS

75

40 30’

40 15’

74 50’

Figure 4. Drainage basins influent to the feeder section of the Delaware and Raritan Canal 

and 1986 integrated terrain land use (ITU), Hunterdon and Mercer Counties, New Jersey.

Urban, 1986

Agricultural, 1986

Undeveloped, 1986

13.6

60.8

25.5

ITU land use Percent of total

Influent stream

Delaware and Raritan Canal

Influent basin

Sampling location

EXPLANATION Lockatong Creek

Wickecheoke Creek

De al wa er

R

vi er

PENNSYLVANIA

Raven 

Rock

Brookville

Lower Ferry Road

NEW JERSEY

Stockton

Lumberville

Project area

0 5 10 MILES

0 5 10 KILOMETERS

40

30’

75

40

15’

74 30’

Hunterdon County

Somerset County

Middlesex County

Mercer County

Raven Rock

Brookville

Lower Ferry Road

PENNSYLVANIA

NEW JERSEY

New

Jersey
10

New Brunswick. Of the eight sites, six were 

equipped with continuous water-qualitymonitoring equipment. Instantaneous waterquality samples also were collected at five of 

these sites. The other two sites were used to 

collect only instantaneous water-quality 

samples. One site was used only to 

continuously monitor water quality. 

Instantaneous samples were collected after 

more than a 0.5 inch of precipitation fell in the 

study area. Nonstorm samples were collected 

after a 10-day period with precipitation no 

greater than 0.5 inch falling in the study area. 

Water quality during storms and nonstorm 

conditions was compared to determine the 

changes caused by stormwater runoff that 

entered the canal.

Site Selection

The sites selected for the study are 

points along the canal that could be affected 

by runoff from influent basins upstream and 

the two points used to define the most 

upstream and downstream locations of the 

study area of the canal (fig. 1). The eight sites 

are described below in downstream order.

The Raven Rock site is in Hunterdon 

County (fig.1). It is 0.75 miles downstream 

from the Bulls Island inlet (fig. 4), which 

diverts water from the Delaware River into the 

canal. It is also the location of the feeder 

sluice gates that regulate the flow to the canal. 

The water quality at this site was considered 

to be an indicator of the quality of the water 

entering the canal from the Delaware River.

The Brookville site is also in 

Hunterdon County. It is 5.1 miles downstream 

from the feeder gates at Raven Rock at a 

bridge over the canal and is 1.8 miles south of 

Stockton (fig. 4). The spillway from the 

Wickecheoke Creek is located 2.3 miles 

upstream, and the Lockatong Creek spillway 

is located 3.9 miles upstream (fig.4). These 

are the two largest influent basins that drain 

into the canal. Their combined drainage area 

is 34,827 acres. A quarry, which is near the 

site, contributes stormwater runoff that enters 

the canal at a point just upstream from the site.

The Lower Ferry Road site is just 

upstream from Trenton City, Mercer County, 

at Lower Ferry Road at the bridge that crosses 

over the canal (fig. 4). It is 12.9 miles 

downstream from Brookville and 18 miles 

downstream from Raven Rock. Many 

spillways and culverts are located between the 

Brookville and Lower Ferry Road sites, 

approximately 10.9 miles downstream from 

the Lambertville feed gates. Land use in the 

influent basins between this site and the Raven 

Rock site is 13.6 percent urban, 60.8 percent 

agricultural, and 25.5 percent undeveloped 

(fig. 4).

The Port Mercer site is at Port Mercer 

in Mercer County at the Province Line 

(Quaker Bridge) Road bridge that crosses over 

the canal. It is 4.7 miles downstream from 

Trenton and 10.7 miles downstream from 

Lower Ferry Road. A small part of the canal 

runs through a culvert underneath U.S. Route 

1, a major highway, for approximately 

1.16 miles. This site is at the end of a reach 

that is surrounded by an urban area (Trenton) 

and at the beginning of a reach surrounded by 

land that was originally agricultural, but is 

rapidly becoming urban.

The Griggstown site is at the 

Griggstown causeway in Somerset County, 

where the causeway bridge crosses the canal. 

It is 11.3 miles downstream from Port Mercer 

(fig. 1). At this point, the canal extends in the 

northeastern direction parallel to the Millstone 

River. Some storm drains that carry water 

from a large quarry 3.7 miles upstream from 

this site empty directly into the canal. The 

land use in the influent basins downstream 

from the site and upstream from the next 

monitoring site is about 16 percent urban and 

61 percent agricultural, as determined from 

the 1986 ITU land-use coverage.

The Ten Mile Lock site is in Somerset 

County. It is 8.9 miles downstream from 

Griggstown and 2 miles downstream from 

Millstone Borough across the canal and the 

Millstone River from Manville. This site is 

0.3 miles upstream from the intake for one of 

the water purveyors. Land in the influent 

drainage basins downstream from this site is 

heavily urbanized.
11

The Landing Lane Bridge site is in 

New Brunswick, Middlesex County, 

approximately 7.5 miles downstream from 

Ten Mile Lock and 6.4 miles downstream 

from the town of South Bound Brook. The 

bridge at this site is the last one before the 

canal ends at the Route 18 Spillway, 

approximately 0.22 miles downstream. The 

drainage basin at the town of South Bound 

Brook (5.2 mi upstream from Landing Lane 

Bridge) consists primarily of road storm 

drains that discharge into the canal. The canal 

makes another sharp turn to the southeast and 

parallels the Raritan River. Als Brook Basin 

(fig.1) drains 2,411 acres and is the largest 

influent drainage basin located along the reach 

between Ten Mile Lock and Landing Lane 

Bridge.

The Route 18 Spillway site is at New 

Brunswick, Middlesex County. This 

continuous water-quality monitoring site is on 

the bank opposite the Route 18 Spillway; at 

this point on the left bank looking 

downstream, the canal empties into the 

Raritan River. The intakes of several water 

purveyors are on the canal just downstream 

from this site. One small influent basin with 

an area of 53 acres drains into the canal 

between Landing Lane Bridge and the Route 

18 Spillway.

Continuous-Monitoring Sites

All sites except Brookville and 

Landing Lane Bridge were used for 

continuous monitoring. Brookville was not 

used because of the proximity of Raven Rock. 

The Landing Lane Bridge site was not used 

because of the difficulty of mounting the 

continuous water-quality monitor on the steel 

bridge. The continuous water-qualitymonitoring sensors at all six sites were placed 

approximately 2 feet below the average 

surface elevation of the canal water. The depth 

of the sensors is about one-third of the average 

depth of water (approximately 6 feet) in the 

canal. The actual location of the continuous 

water-quality monitor differed in some cases 

from that of the instantaneous water-quality 

sampling site because the monitors measure 

water quality at a point, whereas the 

instantaneous water samples are depth- and 

width-integrated. For example, at Raven Rock 

the monitor was mounted on the left retaining 

wall of the canal 200 feet downstream from 

the feed gates so that the gates would protect 

the monitor from large debris such as tree 

limbs. At the Lower Ferry Road, Port Mercer, 

and Griggstown sites, the monitors were 

positioned near the midpoint of the canal on 

the downstream side of each bridge to protect 

the monitors from large debris. At the Ten 

Mile Lock site, the monitor was attached to 

the right retaining wall, 20 feet upstream from 

the weir. At the Route 18 Spillway site, the 

monitor is on the right retaining wall just 

upstream from the end of the canal, near the 

raw water intakes for two water-treatment 

plants.

Instantaneous Water-Quality SampleCollection Sites

The water column in the canal was 

sampled at seven of the eight study sites. The 

Route 18 Spillway site could not be used for 

instantaneous water-quality sampling because 

flow was not uniform at this site. Also, water 

was almost always flowing at the Route 18 

Spillway on the left bank, which promoted 

algal growth on the spillway during the study. 

Therefore, a good cross-section sample of 

water flowing over the Route 18 Spillway 

could not be obtained safely because algal 

growth made the surface of the spillway 

slippery.

Samples were collected at the centroid 

of flow upstream from the weir at Ten Mile 

Lock to avoid collecting a nonrepresentative, 

aerated sample. At Raven Rock, samples were 

collected from the upstream side of the bridge, 

upstream from the feed gates, also to avoid 

collecting a nonrepresentative, aerated sample. 

At both of these sampling sites, the canal 

narrows before water flows through gates or 

over a weir, which creates excellent stream 

mixing. At four of the five remaining sites, the 

samples were collected on the upstream side 

of the bridge; at the Port Mercer site, the 

samples were collected on the downstream 

side of the bridge because no walkway is 

present on the upstream side.
12

Water-Quality Sampling

A total of 63 samples were collected at 

all sites except the Route 18 Spillway during 

nine sampling rounds--five storms and four 

nonstorm events. The instantaneous water 

samples were analyzed for nitrogen species 

(nitrite, nitrite plus nitrate, ammonia, and 

ammonia plus organic nitrogen in filtered 

samples, and ammonia plus organic nitrogen 

in whole water samples), phosphorous in 

filtered and unfiltered samples, total 

suspended solids, suspended organic carbon, 

dissolved organic carbon, UV 254nm, and 

29 VOCs; specific conductance and turbidity 

were measured in the field. Samples analyzed 

for VOCs were collected during four storms 

and four nonstorm events. Three additional 

sampling rounds were conducted during 

nonstorm conditions. These samples were 

analyzed for total suspended solids. Specific 

conductance, temperature, and turbidity were 

measured in the field when the three 

additional nonstorm samples were collected.

Storm condition samples were 

collected whenever there was sufficient 

precipitation to cause appreciable runoff into 

the canal. This criterion was met when more 

than 0.5 in. of precipitation fell in a 24-hour 

period over the entire study area. Storm 

sampling commenced toward the end of the 

precipitation, and all samples were collected at 

seven locations in less than 8 hours. The five 

storm-sampling rounds were conducted on 

September 8 and October 8, 1998, and on 

February 2, May 19, and May 25, 1999. 

Nonstorm sampling rounds were conducted on 

March 30, June 29, November 12, and 

December 21, 1998.

 All sampling rounds, whether storm or 

nonstorm, were conducted at least 10 days 

apart to make each round independent of the 

others. The 10-day waiting period was not 

observed for the May 25, 1999, stormsampling round because of a lack of 

precipitation during the study time period and 

the precipitation that occurred on May 19, 

1999, was slightly greater than 0.5 inches. The 

approximate time needed for water to travel 

the length of the canal is 8 to 10 days.

Water-Quality Monitoring

The water-quality constituents selected 

for analysis in this study are those that are 

most likely to be affected by stormwater 

runoff and that could also affect drinkingwater treatment. Maximum Contaminant 

Levels (MCLs) in drinking water have been 

issued by the State of New Jersey for nitrate, 

nitrite, and turbidity. MCLs also have been 

issued by the State for many of the VOCs 

analyzed for in canal water during this study 

(Shelton and Lance, 1999).

Specific conductance also is strongly 

influenced by precipitation and runoff from 

snowmelt and road deicing (Hem, 1992). 

Ammonia, organic nitrogen, suspended 

organic carbon, and total suspended solids 

affect drinking-water treatment. Dissolved 

organic carbon, UV254, and methyl tert-butyl 

ether (MTBE) (one of the 29 VOCs analyzed 

for) affect the color, taste, and odor of 

drinking water, which are aesthetic concerns 

of drinking-water treatment regulated by the 

State of New Jersey Secondary Maximum 

Contaminant Levels (Shelton and Lance, 

1999). Phosphorous, both dissolved and whole 

water, is an essential nutrient for plants (Hem, 

1992) and can enter the canal from the 

Delaware River and from precipitation runoff 

from influent basins. Excessive growth of 

algae can affect drinking-water taste and odor. 

Also, excessive growth of rooted plants can 

reduce the flow of water in the canal (Rutgers 

University, 1981).

Continuous On-Site Measurements

Turbidity, specific conductance, and 

temperature were measured by using a multiparameter water-quality monitor (Yellow 

Springs Incorporated (YSI) 6000 UPG) with 

an internal battery source and data logging 

capability. Each water-quality monitor was 

programmed to record at 30-minute intervals 

for the first 3 months of the study period (midJanuary 1998 through mid-April 1998), then at 

15-minute intervals for the remainder of the 

study period. The continuous water-quality 

data were plotted, reviewed, and edited to 

correct erroneous values. After this review, 

the data were entered into the USGS 
13

Automated Data Processing System (ADAPS) 

database, which is part of the USGS National 

Water Information System (NWIS).

Turbidity.--Turbidity is the 

measurement of suspended solids in a liquid. 

The unit of measurement is the nephelometric 

turbidity unit (NTU), which is determined by 

focusing a beam of light on the sample water, 

and then measuring the light that is scattered 

off the particles. The light source 

recommended for use by the International 

Standards Organization is a light emitting 

diode with a wavelength between 830 and 

890 nanometers. The light is detected by a 

highly sensitive photodiode at a 90o angle 

from the beam of light (Yellow Springs 

Incorporated, 1996).

The optical measurements are very 

susceptible to fouling. For this reason, the 

turbidity probe on the YSI 6000 UPG comes 

equipped with a mechanical wiper that rotates 

on the probe face. This discourages the build 

up of biological debris and the formation of 

bubbles from outgassing. The values are 

calculated from an average of eight readings 

taken at 4-second intervals (Yellow Springs 

Incorporated, 1996).

Specific Conductance.--Specific 

conductance is the ability of a substance to 

conduct an electrical current. It is the 

reciprocal of resistivity. The presence of 

charged ions allows a solution to conduct an 

electrical current. As the ion concentration 

increases, the conductance of the solution 

increases. For this reason conductance 

provides an indication of ionic strength (Hem, 

1992).

The YSI 6000 UPG incorporates a cell 

with four pure nickel electrodes. Two of the 

electrodes are current driven, and two are used 

to measure the voltage drop. The voltage drop 

is then converted into a conductance value in 

millisiemens and multiplied by the cell 

constant to arrive at a value in microsiemens 

per centimeter (μS/cm) (Yellow Springs 

Incorporated, 1996).

Temperature.--The YSI 6000 UPG 

contains a thermistor of sintered metallic 

oxide which changes predictably in resistance 

with temperature variations. An algorithm is 

built into the YSI 6000 UPG software that 

converts the resistance to temperature in 

degrees Celsius, Kelvin, or Fahrenheit 

(Yellow Springs Incorporated, 1996).

Calibration Procedures

All continuous water-quality monitors 

were calibrated in the New Jersey District 

field laboratory a few hours prior to 

deployment in the field to ensure accurate 

measurements. Once the calibrated monitors 

were installed at a measurement site, the 

monitor readings were checked against 

calibrated portable field meter readings prior 

to unattended operation. Approximately every 

2 weeks, the water-quality readings from the 

monitors were checked against portable field 

meter readings, then the monitors were 

replaced with newly calibrated monitors. This 

cycle was repeated for the duration of the 

project. If the difference between readings 

from the monitor and the field meter was not 

within acceptable limits, the difference was 

recorded and a correction or deletion was 

made to the continuous water-quality records 

after analysis of the data in the New Jersey 

District office.

Turbidity.--A two-point calibration, at 

0 and 100 NTU, was performed just prior to 

deployment of the monitor. In most cases, this 

calibration range is sufficient because the 

majority of readings occur in this range and 

the calibration of the sensor is linear between 

100 and 1000 NTU (Yellow Springs 

Incorporated, 1996). The standards were 

freshly prepared at the time of calibration. 

Filtered, de-ionized water was used for the 

0 NTU standard, and the 4,000 NTU formazin 

was diluted to prepare the 100 NTU standard. 

Calibration was performed in the New Jersey 

District field laboratory, and not in the field, 

because turbidity is not temperature 

compensated and formazin turbidity standards 

change with temperature. The standards 

provided a means of determining whether 

adjustments were needed for the previously 

collected data as a result of calibration drift.
14

Specific Conductance.--The 

conductivity of solutions of ionic species is 

highly dependent on temperature. For this 

reason, the YSI 6000 UPG monitor uses 

temperature and raw conductivity values to 

generate a specific conductance value 

compensated to 25o C (Yellow Springs 

Incorporated, 1996). A two-point calibration 

that bracketed the expected field values was 

performed in the New Jersey District field 

laboratory just prior to deployment of the 

monitor. The field laboratory provided a 

controlled environment for the monitor and 

the standards.

Temperature.--No calibration or 

maintenance of the temperature sensor is 

required (Yellow Springs Incorporated, 1996). 

Before initial deployment, a three-point 

thermistor check of the sensor was performed 

by using a National Institute for Science and 

Technology (NIST) traceable thermometer.

Instantaneous Water-Column WaterQuality Sampling

The four nonstorm sampling rounds 

were conducted by USGS personnel. The five 

storm sampling rounds were conducted by 

NJWSA. Employees of the NJWSA, who 

collected all storm samples, used the methods 

of collection and field measurements also used 

by the USGS. USGS personnel performed all 

sample processing. Both collection and 

processing were performed following the 

guidelines set forth in the USGS National 

Field Manual for the Collection of WaterQuality Data (Wilde and others, 1998). 

Analyses were performed at the USGS 

National Water Quality Laboratory (NWQL) 

in Lakewood, Colorado, with the exception of 

the analysis for UV254, which was performed 

at the USGS New Jersey District laboratory 

(NJWRDL). All water-quality data for the 

Delaware River at Lumberville, Pa., and at 

Trenton, N.J., were obtained as part of the 

USGS-New Jersey Department of 

Environmental Protection Cooperative Surface 

Water Quality Ambient Network and were 

used for comparisons with the water quality in 

the canal.

Sample collection.--Samples were 

collected using a weighted bottle sampler 

equipped with a 1-liter polyethylene bottle and 

suspended from a polyethylene rope. Samples 

were collected at equal increments across the 

canal using depth integration to produce a 

representative sample. At the Raven Rock and 

Ten Mile Lock sites, the samples were 

collected at the centroid of flow, upstream 

from either the sluice gates or the weir, 

respectively.

During nonstorm sampling, the sample 

water was collected at five increments across 

the canal, composited into a clean 10-liter 

churn splitter previously rinsed with canal 

water and taken back to the van for processing 

on site. During storms, the water was collected 

in field-rinsed, 1-liter polyethylene bottles and 

placed on ice to be processed the next day. 

The samples for organic carbon analysis were 

collected in baked, amber glass bottles at the 

centroid of flow about 1-foot below the water 

surface and placed on ice until processed. The 

samples for VOCs also were collected at the 

centroid of flow by using a vendor-certified 

precleaned disposable teflon bailer and 

immediately dispensed into baked, amber 

vials.The vials were examined to be certain 

that no air was present in the vials after filling; 

vials were then placed into an ice filled cooler.

Sample processing.--Samples were 

churned at a uniform rate of about 9 inches per 

second with care being taken not to break the 

surface of the water. The baffled piston of the 

churn was moved up and down a minimum of 

ten times to ensure proper mixing, and the 

sample was dispensed into polyethylene 

bottles that were pre-rinsed twice with deionized water (DI) and once with canal water 

prior to filling for analysis of unfiltered 

nutrient constituents. The unfiltered nutrient 

samples were preserved with sulfuric acid 

(H2SO4) to a pH of <2 and immediately 

chilled.

The sample water was then filtered 

through a 0.45-μm pore-size disposable 

Gelman filter pre-conditioned with 1 liter of 

DI water. The sample bottles also were rinsed 

twice with DI water and once with filtered 

canal water prior to filling. These samples 

were analyzed for dissolved (filtered) 
15

constituents. The filtered samples to be 

analyzed for nutrients were treated with 

sulfuric acid (H2SO4) to a pH of <2. The 

samples were then chilled.

The samples for analysis of organic 

carbon and UV254 were filtered in a stainless 

steel Gelman filter using a 0.45-μm pore-size 

silver filter. The sample water that passed 

through the silver filter was collected in baked 

glass amber bottles, then analyzed for 

dissolved organic carbon (DOC) and UV254. 

The suspended organic carbon (SOC) particles 

were retained on the silver filter, which was 

placed into a covered petri dish and chilled 

prior to analysis.

Samples collected during storms and 

nonstorm conditions were processed in the 

same manner; however, the storm samples 

were processed the next day at the USGS field 

laboratory. The processed samples were 

shipped overnight to the USGS NWQL. The 

analysis for UV254 was performed at the 

NJWRDL.

Laboratory and Field Analyses

Total suspended solids.--Total 

suspended solids are that part of total solids 

retained by a filter after drying. A well-mixed 

sample is filtered through a weighted standard 

glass-fiber filter, and the residue retained on 

the filter is dried to a constant weight in an 

oven at 103 to 105 oCelsius. The increase in 

weight of the filter represents the total 

suspended solids (Eaton and others, 1998).

Whole water and filtered nitrogen 

species.--The nitrogen species in the analyses 

included dissolved nitrite (NO2) as N, 

dissolved nitrite plus nitrate (NO2 + NO3) as 

N, dissolved ammonia (NH3) as N, and total 

and dissolved ammonia nitrogen plus organic 

nitrogen, also called Kjeldahl nitrogen. The 

whole water represents the total nitrogen 

species, and the dissolved species are that 

which pass through a 0.45-μm pore-diameter 

filter.

Whole water and filtered 

phosphorous.--Phosphorous is a rather 

common element in igneous rock and is fairly 

abundant in sediments. It is a component of 

sewage and is always present in animal 

metabolic waste (Hem, 1992). It is present in 

natural waters and in wastewaters almost 

solely as phosphate (Eaton and others, 1998). 

The whole-water sample represents the total 

phosphorous, and the dissolved phosphorous 

is that which passes through a 0.45 μm-porediameter filter.

Dissolved and suspended organic 

carbon.--Organic carbon is composed of a 

variety of organic compounds in various 

oxidation states (Eaton and others, 1998). 

Dissolved organic carbon (DOC) is the 

fraction of total non-volatile organic carbon 

(TOC) that passes through a 0.45-μm-pore 

diameter silver filter; suspended organic 

carbon (SOC) is the fraction of TOC that is 

retained by the filter.

The method used to measure the DOC 

is the ultraviolet-promoted persulfate 

oxidation method. The principle behind this 

method is that organic carbon is oxidized to 

carbon dioxide (CO2) by persulfate in the 

presence of ultraviolet light. The CO2 is 

purged from the sample, dried, and transferred 

with a carrier gas to a nondispersive infrared 

spectrometer for measurement (Eaton and 

others, 1998).

The SOC is detected by the wetoxidation method. In this method, the sample 

is acidified, purged to remove inorganic 

carbon, and oxidized with persulfate in an 

autoclave to temperatures from 116 to 130 o

C. 

The resultant CO2 is then measured by a 

nondispersive infrared spectrometer 

(Burkhardt and others, 1997).

Specific conductance.--Specific 

conductance is the ability of an aqueous 

solution to conduct an electric current 

(conductance) of a body of unit length and 

unit cross-section at a specified temperature 

(Hem, 1992). The specific conductance 

measurements were performed both at the 

USGS NWQL and in the field. The standard 

temperature for laboratory measurement is 

25 oC. All field measurements were made by 

using temperature compensated meters.
16

Ultraviolet absorbance at 254 

nanometers.--Some dissolved organic 

compounds commonly found in water and 

wastewater strongly absorb ultraviolet (UV) 

radiation. Ultraviolet radiation is light that has 

a wavelength of between 100 and 

400 nanometers. UV-absorbing organic 

constituents in a sample absorb UV light in 

proportion to their concentration. UV 

absorption is measured at 253.7 nanometers 

(UV254). Although UV absorption can be 

used to detect certain individual organic 

contaminants, UV254 is intended to be used to 

provide an indication of the aggregate 

concentration of UV-absorbing organic 

constituents in filtered sample water (Eaton 

and others, 1998).

Volatile organic compounds.--The 

method of analysis used for VOCs is purge 

and trap gas chromatography/mass 

spectrometry (GC/MS). This technique 

involves the transfer of the VOCs from an 

aqueous phase to a gaseous phase by bubbling 

an inert gas (such as helium) through a water 

sample contained in a purging chamber. The 

vapor is swept through a trap that adsorbs the 

target compounds or constituents. The trap is 

then heated and backflushed with the same 

inert gas to desorb the compounds onto a gas 

chromatographic column. The gas 

chromatograph is temperature-programmed to 

separate the compounds, which are then 

detected by a mass spectrometer (Connor and 

others, 1998). During this study, 29 target 

compounds or constituents were analyzed for 

in canal water. The analysis used for this 

project has 29 target compounds for which 

concentrations were reported and stored in 

NWIS.

Turbidity.--Turbidity measurements 

were performed in the field. Turbidity in water 

is caused by suspended and colloidal matter 

such as clay, silt, finely divided organic and 

inorganic matter, and plankton and other 

microscopic organisms. Turbidity is an 

expression of the optical property that causes 

light to be scattered and absorbed rather than 

transmitted with no change in direction or flux 

level through the sample. The nephelometric 

method was used during his study; thus the 

unit of measurement is the nephelometric 

turbidity unit (NTU). This method consists of 

using a beam of light to illuminate the sample 

and a photoelectric detector to indicate the 

intensity of light scattered at 90o

 to the path of 

the incident light (Eaton and others, 1998).

Data Analysis

Continuous Water-Quality Data

All continuously monitored waterquality data collected during this study that 

met the data-quality objectives of the study are 

presented in Deluca and others (2000).

Data Preparation.--Continuously 

monitored turbidity and specific conductance 

data for the study period (mid-January 1998 to 

mid-April 1999) were retrieved from the 

USGS NWIS water-quality database 

(QWDATA). Initially, the data were 

electronically recorded at 30-minute intervals. 

After 3 months, the data were reviewed, and 

the data-recording interval was reduced to 

15 minutes because of rapid changes in 

turbidity during storms. To make the data for 

the project compatible for the entire study 

period, every second value was eliminated 

from the 15-minute interval data for each site 

so that the data set would consist of values 

recorded at 30-minute intervals. Then the 

retained values were merged with the 30-

minute interval data recorded during the first 

3 months of the study. The data for all six 

continuous monitoring sites were then merged 

into one file to facilitate the analysis for the 

five stream reaches.

The data had two limitations. First, the 

continuous water-quality monitoring 

instruments were subject to failure from time 

to time, resulting in periods of lost 

observations throughout the period of this 

study. Second, a drought emergency was 

declared by the Delaware River Basin 

Commission from December 14, 1998, to 

February 2, 1999 (William E. Harkness, U.S. 

Geological Survey, written commun., 1998 

and 1999), resulting in mandated flow 

reductions in two steps. Mandated flow was 

85 million gallons per day beginning on 

December 14, 1998, and 70 million gallons 

per day beginning on December 23, 1998. 
17

Normal flow resumed on February 2, 1999. 

The reductions in flow during the drought 

emergency increased the time of travel.

The first data limitation resulted in lost 

records of net change in a reach defined by 

upstream and downstream continuous 

monitoring sites because of instrument failure, 

which was random and rarely occurred for the 

same parcel of water passing each site. The 

upstream data were lagged in time so that the 

same parcel of water was measured by both 

the upstream and downstream water-quality 

monitors. The second limitation required the 

computation of time-lag values for the periods 

of unreduced flow, the period after the first 

flow reduction, and the period after the second 

flow reduction.

Analysis of the Change in Water 

Quality in a Reach.--The objective of the 

analysis of the continuously monitored waterquality data was to determine the mean and 

median net change in turbidity and specific 

conductance. A peak in the outflow at the 

downstream station of a reach was matched 

with the corresponding peak at the upstream 

station of a reach to determine the mean travel 

time in the reach; this travel time was used as 

the lag time to calculate the difference or net 

change in turbidity and specific conductance. 

This process was repeated for each reach for 

the periods of normal flow and for the period 

following the second flow reduction 

(70 percent of normal flow). This approach to 

interpreting continuously monitored data is 

possible because the flow rate in the canal is 

actively controlled to maintain a fairly 

constant rate within + 10 percent over long 

periods of time (months), and relatively few 

data gaps break the continuous data record. 

During the drought emergency, the lag time 

for the short period of the first flow reduction 

was estimated by averaging the lag time of the 

normal flow and the lag time of the second 

flow reduction for each reach.

The mean and median1 were computed 

for the series of values of net change for each 

reach. An estimate of the systematic value 

is the mean or median (Helsel and Hirsch, 

1992). If the estimate of the time of travel is 

reasonably accurate, the systematic value of 

the net change in turbidity or specific 

conductance in a reach represents water 

quality in the canal altered by water from 

influent drainage basins, and the biological, 

chemical, and physical processes that occurred 

in a reach over long periods (months). The 

mean of net changes is more likely to be 

affected by extremely large values, either 

positive or negative, than is the median.

Instantaneous Water-Quality Data

All instantaneous water-quality data 

were reviewed for sample consistency among 

related constituents. For example, the total 

phosphorous concentration should not be less 

than the filtered phosphorous concentration 

within a tolerance based on the laboratory 

analytical precision. All instantaneous waterquality data that passed this data review step 

were published in Deluca and others (2000) 

and were included in the statistical evaluation. 

The data are presented in box plots (Helsel 

and Hirsch, 1992) as a function of sampling 

location, water-quality constituent, and storm 

or nonstorm sample.

The hypothesis tested is that the 

quality of water in the canal was not affected 

by the sampling location along the length of 

the canal, or by storms or nonstorm events. 

All statistical hypotheses were tested by using 

nonparametric statistics at a significance level 

(α) of 0.05. Two types of nonparametric 

statistical tests were used, both using ranktransformed data--a two-way analysis of 

variance (ANOVA) (Helsel and Hirsch, 1992) 

and the Kruskal-Wallis nonparametric test of 

medians for three or more independent 

samples (Daniel, 1990). The Tukey multiple 

comparison test was used to determine 

whether the median concentration of a 

constituent at a particular sampling site and 

during either a storm or nonstorm event was 

significantly different from the median for 

another site, storm or nonstorm event when 

using either the ANOVA or the KruskalWallis tests. First, the hypothesis was tested 

on the median value for a water-quality 

constituent by using a two-way ANOVA. The 

1 The median is the value of the fiftieth percentile when the data are arranged in ascending 

magnitude.
18

relatively small number of data values from a 

sampling site for storm or nonstorm event, a 

maximum of five values, meant that it was 

likely that for either sampling site or event 

type the null hypothesis that the medians are 

statistically the same would be accepted. If the 

null hypothesis was accepted, the 

nonsignificant effect was aggregated, and a 

Kruskal-Wallis nonparametric test was 

performed, followed by another Tukey 

multiple-comparison test. Only data that are 

statistically different are presented in box 

plots in this report.

Relational Database

For this study, water-quality data were 

reorganized and formatted into a relational 

database. Procedures were developed to 

export data from the NWIS into a fully 

normalized relational database (hereafter 

called CanalDB). This section describes the 

database structure and briefly summarizes the 

kinds of data it contains.

The water-quality database was 

structured around a data model that reflects 

the associations and relations among the 

various pieces of information that need to be 

stored and retrieved. The data model was then 

used to generate the physical database. The 

data model was designed using the CASE 

software package, ERwin (version 3.5.2, 

Platinum Technologies Inc.). Once the model 

was completed, ERwin was used to generate 

the physical database in Microsoft Access 97 

format.

The CanalDB data model is described 

in appendix A. All table definitions, and field 

properties and definitions of the CanalDB, are 

listed in a data dictionary, which is the 

primary reference for tables and fields. An 

entity-relation diagram, which shows how 

data elements are linked, also is presented in 

Appendix A (fig. A1). Together, the model 

diagram and the data dictionary serve as the 

basic documentation for CanalDB.

Geographical Information System

A geographic information system 

(GIS) was used to examine the relations 

between water quality in the canal and 

drainage basins influent to the Delaware and 

Raritan Canal. Ellis and Price (1995) delineate 

drainage basins in New Jersey and identify 

those basins that are influent to the canal. 

Their information was augmented with 

information provided by Camp, Dresser & 

McKee (1986) and Ebasco (1988) for the 

feeder section of the canal. Site visits were 

made with NJWSA personnel to the main 

canal to verify that all the influent basins for 

that part of the canal were included in the GIS. 

The land use within the influent basins also 

was incorporated into the GIS. New Jersey 

Department of Environmental Protection 

(1996) integrated terrain unit (ITU) 1986 land 

use was used. Additionally, land use was 

directly interpreted from USGS digital 

infrared orthophoto quarter quads (DOQs) 

(U.S. Geological Survey, 2000) for the Als 

Brook and Duck Pond Run influent basins. 

For Duck Pond Run Basin, the DOQ source 

image dates were 1995 (Princeton-southwest 

and Hightstown-northwest) and 1997 

(Princeton-northeast). For Als Brook basin the 

DOQ source image date was 1995 (Bound 

Brook-southeast and Plainfield-southwest).

WATER QUALITY OF THE DELAWARE AND RARITAN CANAL

The determination of which reaches of 

the canal were affected by stormwater runoff 

is based primarily on the analysis of 

continuous water-quality monitoring data and 

field trip observations because the results of 

the statistical tests were not significant at

α < 0.05.

Samples Collected During Storm and 

Nonstorm Events

 Ammonia and nitrite concentrations in 

filtered samples from the canal were not 

compared statistically by using the KruskalWallis nonparametric test for ranked data for 

the effect of location or storms because the 

concentrations were censored at the USGS 
19

NWQL method reporting levels of 0.02 and 

0.01 mg/L, respectively, for 25 of 62 and 20 

of 62 sample analyses. The range of 

concentrations and median values of nitrite 

and ammonia for all the sampling sites on the 

canal during storm and nonstorm events are 

shown in table 1.

The hypothesis that the quality of 

water in the canal was not affected by 

sampling location, or by storms or nonstorm 

events, was tested for all constituents except 

ammonia and nitrite by using ranktransformed data in a two-way ANOVA. The 

two explanatory variables (treatments) were 

type of sampling event and sampling location. 

No statistically significant difference was 

indicated for the median of any constituent in 

a two-way ANOVA. A relatively small 

number of replicates in each cell of the 

ANOVA, a maximum of five values, resulted 

in a statistically significant difference for only 

one of the explanatory variables because of 

the relatively large range in concentrations. 

Therefore, the values of the nonsignificant 

explanatory variable with the largest 

significance level were aggregated, and the 

Kruskal-Wallis test (equivalent to a one-way 

ANOVA) was performed for each constituent 

except ammonia and nitrite.

Suspended organic carbon (SOC) was 

the only constituent for which the median 

concentration at each sampling site differed 

significantly (α < 0.05) from that at the other 

six sites (fig.5). The median concentrations of 

SOC at the three sampling locations on the 

feeder part of the canal (Raven Rock, 

Brookville, and Lower Ferry Road) were 

significantly greater than that at Ten Mile 

Lock, which is on the main part of the canal. 

The median concentrations of SOC in samples 

collected at Port Mercer, Griggstown, and 

Landing Lane Bridge were not significantly 

different (a > 0.05) from those at the three 

sites on the feeder part of the canal or at Ten 

Mile Lock.

The interquartile range (the value at 

the 75th percentile less the value at the 25th 

percentile, shown as the upper and lower ends 

of the box in the box plot) of SOC for samples 

collected at the three sites on the feeder part of 

the canal is larger than the interquartile range 

for samples from the other sites on the main 

part of the canal, except for Landing Lane 

Bridge (fig. 5). The lowest average velocity, 

0.22 ft/s, of the six reaches defined by 

continuous water-quality monitor sites was 

measured between Ten Mile Lock and the 

Route 18 Spillway. Therefore, the large

Table 1. Maximum, median, and minimum concentrations of nitrite and ammonia in storm and nonstorm samples 

from all sampling sites on the Delaware and Raritan Canal, N.J.

Constituent

Data summary 

descriptor

Concentration during event (mg/L)

Storm Nonstorm

Nitrite as N 

Maximum 0.028 0.023

Median .011 .0135

Minimum 1<.01 1<.01

Ammonia as N

Maximum .16 .093

Median .0375 .02

Minimum 1<.02 1

<.02

1

Laboratory reporting level
20

(9) (9) (8) (7) (9) (9) (8)

SITE

1.81.71.61.51.41.31.21.11.00.90.80.70.60.50.40.30.20.1

CONCENTRATION OF SUSPENDED ORGANIC CARBON, IN MICROGRAMS PER LITER

Raven

Rock

Lower

Ferry Landing Lane Bridge Ten Mile Lock Griggstown Port Mercer Brookville

A A A AB AB B AB

= 0.0035

Travel time from Raven Rock to Route 18 Spillway approximately 8 daysfor all reaches except Ten Mile Lock to Landing Lane Bridge

Travel

time

 approximately

2 days,

6.5 hours

Figure 5. Distributions of concentrations of suspended organic carbon in samples collected during storms and nonstorm conditions at sites on the Delaware and Raritan Canal, N.J., 1998-99.

v 0.45 ft/s v 0.36 ft/s v 0.40 ft/s v 0.22 ft/s v 0.9 ft/s

v 

0.9 ft/s

(9) Number of observations

Outlier data value more than 3 times theinterquartile range outside the quartileOutlier data value less than or equal to 3 andmore than 1.5 times the interquartile rangeoutside the quartileData value less than or equal to 1.5 times theinterquartile range outside the quartile75th percentileMedian25th percentileData value less than or equal to 1.5 times theinterquartile range outside the quartile

EXPLANATION

Storm sample or Delaware River sample. Same letter indicates median values that do not differ significantly at the 95 percent confidence level as determined by Tukey’s multiple comparison test. Also shown by thesame shade between the interquartile range.Average velocity, in feet per second (ft/s)

A
21

interquartile range for SOC in samples 

collected at Landing Lane Bridge would not 

be caused by inflows to the canal upstream 

from Ten Mile Lock because the particles that 

are larger than clay particles and that have a 

density greater than that of water would tend 

to settle and not be transported to Landing 

Lane Bridge in the approximately 2.27 days 

needed for canal water to go from Ten Mile 

Lock to Landing Lane Bridge, which is 

approximately 0.22 miles upstream from the 

Route 18 Spillway.

When compared statistically by using 

the Kruskal-Wallis test (Daniel, 1990), 

stormwater that entered the canal significantly 

(α < 0.05) changed the median value of 

ammonia plus organic nitrogen (fig. 6), 

organic carbon (fig. 7), and UV254 (fig. 8; 

table 2) in filtered water samples collected 

during storms from that collected during 

nonstorm sampling. Median concentrations of 

nitrite plus nitrate (fig.9) and phosphorus 

(fig. 10; table 2) in filtered samples collected 

during storms were not significantly different 

(α >0.05) from those in filtered samples 

collected during nonstorm conditions.

The following water-quality 

constituents analyzed for in whole-water 

samples collected from the canal during 

storms had medians that were significantly 

larger (a < 0.05) than the medians of nonstorm 

samples: phosphorus (fig. 11), turbidity 

(fig.12), ammonia plus organic nitrogen 

(fig. 13) (table 2). The following constituents 

analyzed for in whole water or unfiltered 

samples collected during storms did not have 

medians that were significantly larger 

(a>0.05) than the medians for samples 

collected during nonstorm events: specific 

conductance (fig. 14), suspended organic 

carbon (fig. 15), MTBE (fig. 16), and total 

suspended solids (figure 17; table 2).

Storms that produced runoff to the 

canal were shown to significantly affect the 

median concentrations of 6 of the 12 waterquality constituents that were statistically 

evaluated (table 2). Median concentrations of 

total and dissolved ammonia plus organic 

nitrogen increased during storms. Because 

concentrations of ammonia are relatively 

small, ammonia plus organic nitrogen is 

important to the quality of stormwater that 

enters the canal. The median concentration of 

total phosphorous increased during storms, 

and the median concentration of dissolved 

phosphorous did not (dissolved phosphorous 

concentrations were small). Thus, particulate 

phosphorous is an important factor in the 

quality of stormwater that enters the canal. 

The median concentration of total suspended 

solids did not increase during storms; 

however, the median concentration of 

turbidity did increase during storms. This 

seeming inconsistency in the results was 

probably caused by the poorer precision in 

measuring total suspended solids than in 

measuring turbidity. Total suspended solids 

are reported to one significant figure, and 

turbidity is reported to two significant figures.

A comparison was made of aggregated 

water-quality data from all sampling sites on 

the canal and data from the Delaware River 

near the intake of the canal, by constituent. 

The sampling site on the Delaware River at 

Lumberville, Pa., which is 0.7 miles 

downstream from the intake, is the site with 

water-quality data that is closest to the intake. 

Water-quality data for this site are available 

for all constituents studied, except for VOCs 

and field measured tubidity. The sampling site 

on the Delaware River, nearest the intake, 

with data on VOCs is the Delaware River at 

Trenton, N.J., which is approximately 

20 miles downstream from the intake. Field 

measured turbidity data for the Delaware 

River were not available for comparison with 

the turbidity data for the canal.

Median values of all constituents 

except ammonia, nitrite, and dissolved 

phosphorous in nonstorm samples from the 

canal were not significantly different

(α > 0.05) from that in samples collected from 

the Delaware River at Lumberville, Pa., 

during a 5-year period (water years 1995 

through 1999) during storms and nonstorm 

events. Storms with precipitation of more than 

0.5 inches in one day are relatively rare and 

occurred at Trenton, N.J., for about 7 percent 

of the storms during the period of record for 

this rain gage, 1913-81 (R.D. Schopp, U.S. 

Geological Survey, written commun., 1999). 

Concentrations of ammonia, nitrite, and 

dissolved phosphorous in filtered water from 
22

(29) Number of observations

Outlier data value more than 3 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3 and

more than 1.5 times the interquartile range

outside the quartile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

75th percentile

Median

25th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

EXPLANATION

Figure 6. Distribution of concentrations of 

ammonia plus organic nitrogen in filtered samples 

collected during storms and nonstorm conditions

from the Delaware and Raritan Canal, N.J., and 

the Delaware River at Lumberville, Pa.

(32)

0

0.7

0.1

0.2

0.3

0.4

0.5

0.6

0.7

FILTERED KJELDAHL NITROGEN DISSOLVED, 

IN MILLIGRAMS PER LITER

A

(29) (22)

B B

= 0.0001

STORMS NONSTORM

CONDITIONS

DELAWARE

RIVER AT

LUMBERVILLE,

PA

Storm sample or Delaware River sample.

Same letter indicates median values that 

do not differ significantly at the 95 percent 

confidence level as determined by Tukey’s 

multiple comparison test. Also shown by the 

same shade between the interquartile range.

A

(29) Number of observations

Outlier data value more than 3 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3 and

more than 1.5 times the interquartile range

outside the quartile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

75th percentile

Median

25th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

EXPLANATION

Figure 7. Distribution of concentrations of 

dissolved organic carbon in samples collected 

during storms and nonstorm conditions from the 

Delaware and Raritan Canal, N.J., and the 

Delaware River at Lumberville, Pa.

(33)

DISSOLVED ORGANIC CARBON, IN MILLIGRAMS PER LITER

A

(29) (21)

B B

= 0.0019

0

8

2

4

6

STORMS NONSTORM

CONDITIONS

DELAWARE

RIVER AT

LUMBERVILLE,

PA

A Storm sample or Delaware River sample.

Same letter indicates median values that 

do not differ significantly at the 95 percent 

confidence level as determined by Tukey’s 

multiple comparison test. Also shown by the

same shade between the interquartile range.
23

(29) Number of observations

Outlier data value more than 3 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3 and

more than 1.5 times the interquartile range

outside the quartile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

75th percentile

Median

25th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

EXPLANATION

Figure 8. Distribution of ultraviolet absorbance 

at 254 nanometers in filtered samples collected 

during storms and nonstorm conditions from the 

Delaware and Raritan Canal, N.J., and the 

Delaware River at Lumberville, Pa.

(28) (29) (7)

0

0.35

0.05

0.10

0.15

0.20

0.25

0.30

0.35

ULTRAVIOLET ABSORBANCE AT 254 NANOMETERS

= 0.026

A B AB

STORMS NONSTORM

CONDITIONS

DELAWARE

RIVER AT

LUMBERVILLE,

PA

A Storm sample or Delaware River sample.

Same letter indicates median values that 

do not differ significantly at the 95 percent 

confidence level as determined by Tukey’s 

multiple comparison test. Also shown by the 

same shade between the interquartile range.

(29) Number of observations

Outlier data value more than 3 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3 and

more than 1.5 times the interquartile range

outside the quartile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

75th percentile

Median

25th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

EXPLANATION

Figure 9. Distribution of concentrations of nitrate 

plus nitrite nitrogen in filtered samples collected

during storms and nonstorm conditions from the

Delaware and Raritan Canal, N.J., and the 

Delaware River at Lumberville, Pa.

(32) (22)

0.5

1.4

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

NITRATE PLUS NITRITE NITROGEN, IN MILLIGRAMS PER LITE

R

= 0.75

A

(29)

A A

STORMS NONSTORM

CONDITIONS

DELAWARE

RIVER AT

LUMBERVILLE,

PA

A Storm sample or Delaware River sample.

Same letter indicates median values that 

do not differ significantly at the 95 percent 

confidence level as determined by Tukey’s 

multiple comparison test. Also shown by the 

same shade between the interquartile range.
24

(29)

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

75th percentile

Median

25th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

EXPLANATION

Figure 10. Distribution of concentrations of 

phosphorus in filtered samples collected during 

storms and nonstorm conditions from the 

Delaware and Raritan Canal, N.J.

(32)

0.10

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

DISSOLVED PHOSPHORUS, IN MILLIGRAMS PER LITER

A

(29)

A

= 0.13

STORMS NONSTORM

CONDITIONS

A Storm sample or Delaware River sample.

Same letter indicates median values that 

do not differ significantly at the 95 percent 

confidence level as determined by Tukey’s 

multiple comparison test. Also shown by the 

same shade between the interquartile range.

Number of observations

Outlier data value more than 3 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3 and

more than 1.5 times the interquartile range

outside the quartile

(29)

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

75th percentile

Median

25th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

EXPLANATION

Figure 11. Distribution of concentrations of total 

phosphorus in samples collected during storms

and nonstorm conditions from the Delaware and

Raritan Canal, N.J., and the Delaware River at 

Lumberville, Pa.

(32) (22)

0.02

0.24

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

0.22

TOTAL PHOSPHORUS, IN MILLIGRAMS PER LITER

A

(29)

B B

= 0.0001

0

STORMS NONSTORM

CONDITIONS

DELAWARE

RIVER AT

LUMBERVILLE,

PA

A Storm sample or Delaware River sample.

Same letter indicates median values that 

do not differ significantly at the 95 percent 

confidence level as determined by Tukey’s 

multiple comparison test. Also shown by the 

same shade between the interquartile range.

Number of observations

Outlier data value more than 3 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3 and

more than 1.5 times the interquartile range

outside the quartile
25

(29)

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

75th percentile

Median

25th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

EXPLANATION

Figure 12. Distribution of field turbidity in samples 

collected during storms and nonstorm conditions

from the Delaware and Raritan Canal, N.J.

(33) (29)

0

100

20

40

60

80

FIELD TURBIDITY, IN NEPHELOMETRIC TURBIDITY UNITS

= 0.011

A B

STORMS NONSTORM

CONDITIONS

A Storm sample or Delaware River sample.

Same letter indicates median values that 

do not differ significantly at the 95 percent 

confidence level as determined by Tukey’s 

multiple comparison test. Also shown by the 

same shade between the interquartile range.

Number of observations

Outlier data value more than 3 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3 and

more than 1.5 times the interquartile range

outside the quartile

(29)

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

75th percentile

Median

25th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

EXPLANATION

Figure 13. Distribution of concentrations of total

ammonia plus organic nitrogen in samples 

collected during storms and nonstorm conditions 

from the Delaware and Raritan Canal, N.J., and

the Delaware River at Lumberville, Pa.

(32) (29) (22)

0

3.0

0.5

1.0

1.5

2.0

2.5

TOTAL KJELDAHL NITROGEN, IN MILLIGRAMS PER LITER

= 0.0001

ABB

STORMS NONSTORM

CONDITIONS

DELAWARE

RIVER AT

LUMBERVILLE,

PA

A Storm sample or Delaware River sample.

Same letter indicates median values that 

do not differ significantly at the 95 percent 

confidence level as determined by Tukey’s 

multiple comparison test. Also shown by the 

same shade between the interquartile range.

Number of observations

Outlier data value more than 3 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3 and

more than 1.5 times the interquartile range

outside the quartile
26

(29) Number of observations

Outlier data value more than 3 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3 and

more than 1.5 times the interquartile range

outside the quartile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

75th percentile

Median

25th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

EXPLANATION

Figure 14. Distribution of specific conductance in 

samples collected during storms and nonstorm

conditions from the Delaware and Raritan Canal, 

N.J., and the Delaware River at Lumberville, Pa.

(33) (29) (22)

80

260

280

100

120

140

160

180

200

220

240

SPECIFIC CONDUCTANCE, 

IN MICROSIEMENS PER CENTIMETER

= 0.93

AAA

STORMS NONSTORM

CONDITIONS

DELAWARE

RIVER AT

LUMBERVILLE,

PA

A Storm sample or Delaware River sample.

Same letter indicates median values that 

do not differ significantly at the 95 percent 

confidence level as determined by Tukey’s 

multiple comparison test. Also shown by the 

same shade between the interquartile range.

(29) Number of observations

Outlier data value more than 3 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3 and

more than 1.5 times the interquartile range

outside the quartile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

75th percentile

Median

25th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

EXPLANATION

(30) (21)

0

1.8

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

SUSPENDED ORGANIC CARBON, IN MILLIGRAMS PER LITE

R

= 0.44

A

(29)

A A

STORMS NONSTORM

CONDITIONS

DELAWARE

RIVER AT

LUMBERVILLE,

PA

Figure 15. Distribution of concentrations of 

suspended organic carbon in samples collected

during storms and nonstorm conditions from the

Delaware and Raritan Canal, N.J., and the 

Delaware River at Lumberville, Pa.

A Storm sample or Delaware River sample.

Same letter indicates median values that 

do not differ significantly at the 95 percent 

confidence level as determined by Tukey’s 

multiple comparison test. Also shown by the 

same shade between the interquartile range.
27

(29) Number of observations

Outlier data value more than 3 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3 and

more than 1.5 times the interquartile range

outside the quartile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

75th percentile

Median

25th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

EXPLANATION

(27) (28)

0

3.5

0.5

1.0

1.5

2.0

2.5

3.0

METHYL TERT-BUTYL ETHER, IN MICROGRAMS PER LITER

STORMS NONSTORM

CONDITIONS

A A

= 0.92

Figure 16. Distribution of concentrations of methyl 

tert-butyl ether in samples collected during storms 

and nonstorm conditions from the Delaware and 

Raritan Canal, N.J.

A Storm sample or Delaware River sample.

Same letter indicates median values that 

do not differ significantly at the 95 percent 

confidence level as determined by Tukey’s 

multiple comparison test. Also shown by the 

same shade between the interquartile range.

(29) Number of observations

Outlier data value more than 3 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3 and

more than 1.5 times the interquartile range

outside the quartile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

75th percentile

Median

25th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

EXPLANATION

Figure 17. Distribution of concentrations of total 

suspended solids in samples collected during 

storms and nonstorm conditions from the 

Delaware and Raritan Canal, N.J., and the 

Delaware River at Lumberville, Pa.

(33) (29) (22)

0

80

10

20

30

40

50

60

70

TOTAL SUSPENDED SOLIDS, IN MILLIGRAMS PER LITER

= 0.26

AAA

STORMS NONSTORM

CONDITIONS

DELAWARE

RIVER AT

LUMBERVILLE,

PA

A Storm sample or Delaware River sample.

Same letter indicates median values that 

do not differ significantly at the 95 percent 

confidence level as determined by Tukey’s 

multiple comparison test. Also shown by the

same shade between the interquartile range.
28

the canal were not compared to that from the 

Delaware River at Lumberville because either 

the data were highly censored or the 

laboratory reporting levels were changed. 

Phosphorus in filtered-water samples was not 

statistically evaluated because the laboratory 

lower reporting level was increased from 0.01 

to 0.05 mg/L on October 1, 1998 (the 

beginning of water year 1999) (U.S. 

Geological Survey, 1998). The percentage of 

censored values of phosphorous in filtered 

water to the total number of analyses of 

phosphorous in filtered-water samples 

collected from the Delaware River at 

Lumberville during water years 1995-99 is 

4 percent. The change in laboratory reporting 

level resulted in an increase in the percentage 

of censored values of phosphorous analyzed 

for in filtered-water samples from the canal 

during 1998-99 to 8 percent.

Only 6 of 29 VOCs were detected in 

55 samples of canal water by using purge and 

trap GC/MS analysis with a method reporting 

level of 0.2 μg/L. MTBE was detected in

43 samples; the highest concentration was

3.2 μg/L. Toluene was detected in five 

samples; the highest concentration was

0.7 μg/L. Chloroform was detected in four 

samples, and all the concentrations were 

approximately 0.1 μg/L. Methylene chloride, 

ortho-Xylene, and meta- plus para-Xylenes 

were detected once each at concentrations of 

0.1, 0.2, and 0.5 μg/L, respectively. The 

highest concentration of MTBE and the 

greatest number of analytes were detected in a 

nonstorm sample collected at Brookville. 

None of the 55 samples contained a VOC 

concentration that exceeded 

U.S. Environmental Protection Agency or 

State of New Jersey Primary Drinking Water 

Maximum Contaminant Levels.

 A statistical comparison was 

performed on concentrations of MTBE in 

samples from the canal and in samples from 

the Delaware River at Trenton collected 

during water years 1995-99 (fig. 18). Results 

of the statistical comparison of the medians of 

MTBE concentrations for the two sites 

indicated that they were not significantly 

different (α > 0.05).

Table 2. Results of the Kruskal-Wallis test on median values of constituents in storm and nonstorm samples from all 

sampling sites on the Delaware and Raritan Canal, N. J.

 [--, no data; nm, nanometers]

Constituents in 

filtered water 

Statistically 

significant difference 

in median values 

(storm median value 

was greater than 

nonstorm median 

value)

KruskalWallis 

test, 

alpha 

value

Constituents in 

unfiltered or whole 

water

Statistically 

significant difference 

in median values 

(storm median value 

was greater than 

nonstorm median 

value)

KruskalWallis 

test, 

alpha 

value

Ammonia No statistical test -- Ammonia plus 

organic nitrogen

Yes .0001

Ammonia plus 

organic nitrogen 

Yes .0001 Methyl tert-butyl 

ether (MTBE)

No .92

Nitrite No statistical test -- Phosphorus Yes .0001

Nitrite plus nitrate No .75 Specific conductance No .93

Organic carbon Yes .0019 Suspended organic 

carbon

No .44

Phosphorus No .13 Total suspended

solids

No .26

Ultraviolet absorbance at 254 nm Yes .026 Turbidity Yes .011
29

The results of the nonparametric twoway ANOVA tests showed that the water 

quality at one sampling location was not more 

affected by stormwater runoff into the canal 

than at any of the other six sampling locations. 

The instantaneous water-quality data did not 

reveal a pattern of water-quality change that 

would narrow the focus of a future more 

detailed investigation into the effects of 

stormwater runoff on the water quality of a 

particular reach of the canal.

Continuous Water-Quality Monitoring

The six continuous water-quality 

monitoring locations divide the canal into five 

reaches that cover almost the entire length of 

the canal. Water temperature (T), specific 

conductance (SC), and turbidity were recorded 

every 30 minutes for approximately 1 year and 

3 months, from February 1998 to May 1999. 

The data on SC are summarized in figure 19 

and on turbidity in figure 20. Temperature was 

used solely to correct the specific conductance 

to the reference temperature of 25 o

Celsius. 

Daily maximum, minimum, and mean of 

water temperatures are reported in Deluca and 

others (2000) and stored in CanalDB.

The data from an upstream location 

were lagged in time so that upstream and 

downstream sensors measured the same parcel 

of water. The upstream measurement value 

was subtracted from the downstream value to 

obtain the net change in turbidity or SC that 

occurred in each reach bounded by two 

continuous water-quality monitors. This 

approach to interpreting continuously 

monitored data is possible because the flow 

rate in the canal is actively controlled to 

maintain a fairly constant flow rate within 

+ 10 percent over long periods of time 

(weeks), and relatively few gaps break the 

continuous data record.

 The population of net changes in 

turbidity or SC for the period of record of this 

study has a systematic value and plus or minus 

some amount of random variability. If the 

estimate of the time of travel is reasonably 

accurate, the systematic value represents 

turbidity or SC in a reach of the canal that has 

been altered by water from influent drainage 

(29) Number of observations

Outlier data value more than 3 times the

interquartile range outside the quartile

Outlier data value less than or equal to 3 and

more than 1.5 times the interquartile range

outside the quartile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

75th percentile

Median

25th percentile

Data value less than or equal to 1.5 times the

interquartile range outside the quartile

EXPLANATION

Figure 18. Distribution of concentrations of methyl 

tert-butyl ether in samples collected from the 

Delaware River at Trenton, N.J., during water 

years 1995-99 and the Delaware and Raritan 

Canal, N.J., during water years 1998-99.

(22) (55)

DELAWARE AND

RARITAN CANAL

DELAWARE RIVER

AT TRENTON, N.J.

0

4.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

METHYL TERT-BUTYL ETHER, IN MICROGRAMS PER LITER

A A

Delaware and Raritan Canal sample or 

Delaware River sample. Same letter 

indicates median values that do not differ 

significantly at the 95 percent confidence 

level as determined by Tukey’s multiple 

comparison test. Also shown by the same 

shade between the interquartile range.

A
30

basins, as well as the biological, chemical, and 

physical processes that occurred in a reach 

over long periods of time (months). The mean 

is more likely to be affected by extremely 

large values of net change than is the median.

A comparison of the mean and median 

of a population reveals information about the 

distribution of values of the population. If the 

mean and median values are not similar, then 

the population has a small percentage of 

extremely large or small values that affect the 

mean more than the median (Helsel and 

Hirsch, 1992). The relation between the mean 

and median of the population of net changes 

in turbidity or SC in a reach can be used to 

infer whether or not measurable effects of 

storms had occurred.

Specific Conductance

The range and mean of continuously 

monitored SC for the project period of record 

are shown in figure 19. The mean SC changed 

little along the length of the canal; during the 

period of record the mean ranged from 

196 μS/cm at Lower Ferry Road to 215 μS/cm 

at the Route 18 Spillway. The minimum value 

of SC ranged from 75 μS/cm at Port Mercer to 

115 μS/cm at Route 18 Spillway. The 

minimum values of SC for canal water can be 

compared to the SC of precipitation at 

Washington Crossing, N.J., which has a 

seasonal precipitation-weighted mean of 24 

and 18 μS/cm for 1998 and 1999, respectively 

(National Atmospheric Deposition Program 

(NRSP-3)/National Trends Network 2000, 

2000). Maximum SC is greater downstream 

from influent basins with a large percentage of 

urban land use, 858 μS/cm at Port Mercer and

991 μS/cm at Route 18 Spillway, than 

downstream from influent basins with a large 

percentage of non-urban land use, 290 μS/cm 

at Lower Ferry Road.

The mean and median of net changes 

in SC for the five reaches that constitute 

almost the entire length of the canal are shown 

Figure 19. Minimum, maximum, and mean of continuously monitored specific conductance at 

six sampling locations along the length of the Delaware and Raritan Canal, N.J., February 1998 

to May 1999.

1,000

50

100

200

500

Raven Rock

Lower Ferry Road

Port Mercer

Griggstown

Ten Mile Lock

Route 18 Spillway

Maximum

Minimum

Mean

SPECIFIC CONDUCTANCE, 

IN MICROSIEMENS PER CENTIMETER

AT 25 DEGREES CELSIUS
31

Mean of travel-time lagged net change in a reachMedian of travel-time lagged net change in a reach

 Raven Rock to

Lower Ferry Road

Lower Ferry Road to

Port Mercer

Port Mercer to

Griggstown

Griggstown to

Ten Mile Lock

Ten Mile Lock to

Route 18 Spillway

NET CHANGE IN SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

AT 25 DEGREES CELSIUS

Figure 20. Mean and median of the travel-time lagged net changes in specific conductance in the five reaches of the Delaware and Raritan Canal, N.J., February 1998 to May 1999.

10

98765

4

32

1

0

-1

-2-3

-4

-5-6
32

in figure 20. The change in SC in the reach 

between Raven Rock and Lower Ferry Road 

shows the effect of stormwater runoff from the 

influent basins of Lockatong and 

Wickecheoke Creeks. These two influent 

drainage basins with a combined drainage area 

of 31,802 acres compose the largest drainage 

area in the study area. When the water from 

the Lockatong and Wickecheoke Creeks that 

has a SC lower than the canal water enters the 

canal, the SC of canal water at Lower Ferry 

Road is reduced by approximately

5.5 μS/cm for the mean value and 2.5 μS/cm 

for the median value for the project period of 

record. The differing values of the mean and 

the median net change in SC in a reach 

indicate that a small number of extreme values 

of net change in SC have affected the mean 

more than the median; therefore, the decreases 

in SC are associated with storms and 

stormwater with a lower SC that enters this 

reach of the canal.

If a net change of 5 μS/cm were 

determined by a few field measurements, the 

net change would be within + 3 percent of the 

reading, the accepted measurement accuracy 

for SC (Radtke and others, 1998). The mean 

net change in the reach between Raven Rock 

and Lower Ferry Road is significant because 

the mean is the central value of a population 

of tens of thousands of measurements. The 

continuous-monitoring mean SC is supported 

by the field measurements for SC at 

Brookville, which is immediately downstream 

from the confluence of the Wickecheoke 

Creek and the canal (fig. 4). The means of 

storm and nonstorm field measured SC values, 

which are based on five and four 

measurements, respectively, differed by 

approximately 15 μS/cm.

 In the canal reach between Lower 

Ferry Road and Port Mercer, SC increased to a 

mean of 2.7 μS/cm and a median of 4μS/cm 

for the net changes. A review of the 

continuous data record of the lagged net 

changes showed that an increase in SC in this 

reach occurred mostly during nonstorm 

conditions. The net change in SC that 

occurred in this reach under nonstorm 

conditions can be deduced from the agreement 

between the mean and median values of the 

net change in SC (fig. 20). A possible source 

of high SC water in this reach is domestic or 

industrial wastewater that continuously 

discharges into pipes, which empty into the 

Delaware and Raritan Canal, and ground 

water that flows from areas within this reach 

where the water table is higher than the 

surface-water level of the Delaware and 

Raritan Canal.

The mean and median of the net 

change in SC between Port Mercer and 

Griggstown both increased about 1.9 μS/cm 

(fig. 20). Duck Pond Run is the largest 

influent drainage basin in this reach. During 

1998-99, this basin was undergoing change 

from agricultural and forested land uses to 

urban land use.

Net changes in SC in the reach 

between Griggstown and Ten Mile Lock are 

small, -0.25 μS/cm for the mean and

0.9 μS/cm for the median. Only five small 

influent drainage basins with a total area of 

1,038 acres drain into the canal in this reach.

 The greatest net change in SC in the 

five reaches, an increase of 9.3 and 4.0 μS/cm 

for the mean and median values of the period 

of record of this project, respectively, 

occurred in the most downstream reach 

between the Ten Mile Lock and Route 18 

Spillway. A mean value much larger than the 

median value of net change in SC indicates 

that the net change in SC is associated with 

precipitation runoff from the two largest 

influent basins in this reach, the Borough of 

South Bound Brook and Als Brook. The 

primary land use in the basins influent to this 

reach of the canal is urban, and many storm 

drains in this area empty road runoff into the 

canal. The fourth largest influent drainage 

basin, Als Brook, drains into the canal about 

1.34 miles upstream from the Route 18 

Spillway.

Turbidity

The maximum and minimum turbidity 

for the six continuous water-quality 

monitoring sites is 960 and 0.3 NTU, 

respectively (fig. 21). The mean value of the 

continuously monitored turbidity data for the 

duration of the study increased from 
33

11.8 NTU at Raven Rock to 19.6 NTU at 

Lower Ferry Road, then gradually decreased 

downstream to 8.6 NTU at the Route 18 

Spillway (fig. 21).

The mean and median of net changes 

in turbidity for the five reaches are shown in 

figure 22. The reach between Raven Rock and 

Lower Ferry Road shows the effect of the 

influent basins of Lockatong and 

Wickecheoke Creeks. When the water from 

the Lockatong and Wickecheoke Creeks with 

higher turbidity entered the canal, the turbidity 

at Lower Ferry Road increased over the 

turbidity at Raven Rock by approximately 

7.3 NTU for the mean value and 6.1 NTU for 

the median value of the project period of 

record. The average velocity of the canal 

water in this reach was estimated to be 0.9 ft/s. 

This average velocity was less than the 

commonly accepted 1.5 ft/s needed to 

transport sand.

The canal water between Lower Ferry 

Road and Port Mercer underwent a net change 

in turbidity for the project period of record of

-4 NTU for the mean and -3.4 NTU for the 

median. The average velocity of the canal 

water in this reach is estimated to be 0.45 ft/s. 

Significant attenuation of turbidity occurred in 

this reach. A new housing development was 

under construction near the canal about 

0.25 miles upstream from the Port Mercer 

continuous water-quality monitor. After and 

during a storm, a plume of high-turbidity 

water was visible coming from a storm drain, 

which received overland flow from the 

construction site, and entering the canal on the 

right bank, then hugging the right bank. This 

source of turbid water will probably be 

Raven Rock

Lower Ferry Road

Port Mercer

Griggstown

Ten Mile Lock

Route 18 Spillway

1,000

500

200

100

50

20

10

0.5

0.2

0.1

5

2

1

Maximum

Minimum

Mean

Figure 21. Minimum, maximum, and mean of continuously monitored turbidity at six sampling 

locations along the length of the Delaware and Raritan Canal, N.J., February 1998 to May 1999. NEPHELOMETRIC TURBIDITY UNITS (NTU’S)
34

 Raven Rock to

Lower Ferry Road

Lower Ferry Road to

Port Mercer

Port Mercer to

Griggstown

Griggstown to

Ten Mile Lock

Ten Mile Lock to

Route 18 Spillway

v 0.45 ft/s v 0.36 ft/s v 0.40 ft/s v 0.22 ft/s v 0.9 ft/s

NET CHANGE IN TURBIDITY, IN NTU

Mean of travel-time lagged net changeMedian of travel-time lagged net changeAverage velocityFeet per second

Travel time from Raven Rock to Route 18 Spillway 

approximately 8 days

v

ft/s

Figure 22. Mean and median of the travel-time lagged net changes in turbidity in the five reaches of the Delaware and Raritan Canal, N.J., February 1998 to May 1999.

Travel

time

 approximately 

2 days, 8 hours

8765

4

32

1

0

-1

-2-3

-4

-5-6
35

eliminated once the housing development is 

completed. It is not apparent from a data 

review that the turbid water that entered the 

canal mixed sufficiently with the canal water 

in the 0.25 miles between the storm drain and 

the monitor to be detected by the continuous 

water-quality monitor located almost midway 

across the canal. The period of record mean 

values for turbidity at Lower Ferry Road and 

Port Mercer are 19.6 and 15.6 NTU, 

respectively (fig. 21).

The water in the reach between Port 

Mercer and Griggstown underwent a net 

change in turbidity for the project period of 

record of -0.8 NTU for the mean and

-1.0NTU for the median between the start and 

end of the reach (fig. 22). Almost no change in 

turbidity occurred in this reach, which is an 

unexpected result, because the estimated 

average velocity of the canal water in this 

reach, 0.36 ft/s, was lower than the average 

velocity of the reach between Lower Ferry 

Road and Port Mercer.

The minimal reduction in turbidity in 

the reach between Port Mercer and 

Griggstown could have been caused by 

dredging of the canal in this reach during the 

project. A review of the turbidity values for 

the project period of record showed that the 

turbidity generated by the dredging was 

detected by the Griggstown continuous waterquality monitor. The Duck Pond Run Basin 

drains into the canal in this reach. Stormwater 

from this basin might increase turbidity in this 

reach. The confluence of Duck Pond Run and 

the canal is approximately 11.2 miles 

upstream from the Griggstown continuous 

water-quality monitor. Any settleable solids or 

turbidity that enters the canal from Duck Pond 

Run would settle in the canal during the 45.7 

hours of travel time before being detected by 

the Griggstown continuous water-quality 

monitor. Only duck weed, which floats on the 

water surface, was observed in this reach 

during field trips to the study area. Algae were 

not observed in this reach.

The water in the reach between 

Griggstown and Ten Mile Lock underwent a 

net change in turbidity for the project period 

of record of -5.6 NTU for the mean and

-3.8 NTU for the median (fig. 22). The 

average velocity of canal water in this reach 

was approximately 0.40 ft/s. Thus, the 

attenuation of the turbidity in this reach was 

caused by settling of the suspended particles 

because the velocity of the water was low.

The water in the reach between Ten 

Mile Lock and the Route 18 Spillway 

underwent a net change in turbidity for the 

project period of record of -0.1 NTU for the 

mean and -0.4 NTU for the median (fig. 22). 

The average velocity of the water in this reach 

was approximately 0.22 ft/s, which was the 

lowest average velocity of the six reaches, and 

the net change in turbidity was negligible. If 

little turbidity is added to the canal water from 

influent drainage basins, this reach would 

have measurably large decreases in turbidity 

similar to those in the reach between Ten Mile 

Lock and Griggstown because of the low 

velocity; however, water from Als Brook 

Basin, the fourth largest influent drainage 

basin, and the Borough of South Bound Brook 

drainage basin, which covers an area of 500 

acres, enters the canal about 1.34 miles and 

5.5 miles, respectively, upstream from the 

Route 18 Spillway. Because Als Brook is 

closer to the continuous water-quality monitor 

located at the Route 18 Spillway and has an 

area 5.8 times larger than the Borough of 

South Bound Brook Basin, it was more likely 

to be the source of a significant amount of 

stormwater runoff that carried turbidity into 

the canal. A deposit of sand and gravel is 

present at the confluence of Als Brook and the 

canal and extends almost one-third of the 

width of the canal. No sand and gravel 

deposits in the canal were observed near the 

Borough of South Bound Brook drainage 

basin.

SUMMARY

In general, the chemical composition 

of water in the Delaware and Raritan Canal in 

New Jersey during nonstorm conditions is not 

statistically different from that of the water 

near the intake of the canal, at the Delaware 

River at Lumberville, Pa. The results of 

statistical hypothesis testing of the 

instantaneous water-quality sampling data 

collected during the project period of record, 

mid-January 1998 to May 1999, did not 
36

identify specific locations along the canal at 

which statistically significant changes in 

median values of water-quality constituents 

were associated with storms. To determine 

statistically significant differences for all the 

water-quality constituents, one explanatory 

variable (either precipitation conditions or 

sampling locations) was removed by 

combining either storm and nonstorm data, or 

data from all sampling locations. Thus, the 

results of the analysis of the continuous waterquality monitoring data provided the 

information needed to identify water-quality 

changes related to storms in the five reaches 

of the canal.

The concentrations of ammonia and 

nitrite nitrogen were not statistically tested 

because about 40 and 32 percent, respectively, 

of the data values were less than the method 

reporting level. Concentrations of filtered 

phosphorous in water samples from the canal 

could not be statistically compared with 

concentrations in samples collected at the 

Delaware River at Lumberville, Pa., because 

of a change in the laboratory reporting level in 

1999, from 0.01 to 0.05 milligrams per liter. 

The change in laboratory reporting level 

resulted in a greater percentage of censored 

data from the canal (8 percent) than from the 

Delaware River at Lumberville, Pa. 

(4 percent). The nonstorm median 

concentrations of nine water-quality 

constituents in canal water were not 

significantly different from the median 

concentrations in samples collected during 

water years 1994-99 at the Delaware River at 

Lumberville, Pa., nor was field measured 

specific conductance significantly different.

Only the median concentrations of 

suspended organic carbon differed 

significantly along the length of the canal after 

the storm and nonstorm data were aggregated. 

Median concentrations were significantly 

higher during and after storms than for 

nonstorm events for the following 

constituents: total and filtered ammonia plus 

organic nitrogen, total phosphorous, turbidity, 

ultraviolet absorbance at 254 nanometers, and 

dissolved organic carbon.

Only five volatile organic compounds 

(VOCs) were detected. Toluene was detected 

five times; the highest concentration was 

0.7 μg/L (micrograms per liter). Chloroform 

was detected 4 times, and all the 

concentrations were approximately 0.1 μg/L 

(micrograms per liter). Methylene chloride, 

ortho-Xylene, and meta- plus para-Xylenes 

were detected once each at concentrations of 

0.1, 0.2, and 0.5 μg/L, respectively. Methyl 

tert-butyl ether (MTBE) was the most 

frequently detected VOC. MTBE was detected 

in 55 of 80 samples. The median 

concentration of MTBE in canal water 

(0.25 μg/L) was not statistically different from 

that in water from the Delaware River at 

Trenton, N.J.

Stormwater runoff into the canal reach 

between Raven Rock and Lower Ferry Road 

reduced the continuously monitored specific 

conductance (SC) at Lower Ferry Road 

relative to that at Raven Rock during 1998-99. 

The largest basins that drain into the canal in 

this reach are the Wickecheoke Creek (16,987 

acres) and Lockatong Creek (14,815 acres).

The median of the continuously 

monitored SC for the period of record during 

nonstorm conditions at Port Mercer increased 

by approximately 3 to 4 μS/cm (microsiemens 

per centimeter) (1.5 to 2 percent of the median 

specific conductance), relative to that of the 

nearest upstream site, Lower Ferry Road, 

during 1998-99. Land use in the influent 

basins for this reach of the canal is primarily 

urban.

 The median continuously monitored 

SC for the project period of record during 

nonstorm conditions at the Route 18 Spillway 

site increased relative to that of the nearest 

upstream site, Ten Mile Lock, by 

approximately 3 to 4 μS/cm, during 1998-99. 

The mean of the net change for the period of 

record in continuously monitored specific 

conductance for this reach during storms also 

increased. Land use in the two largest influent 

basins, the Borough of Bound Brook and Als 

Brook, is predominantly urban.

Continuously monitored turbidity 

differed along the length of the canal. 

Between Raven Rock and Lower Ferry Road, 
37

the mean and median for continuously 

monitored turbidity increased by 7.2 and 

6.2 NTU (nephelometric turbidity units), 

respectively, during 1998-99. The 

continuously monitored turbidity decreased 

downstream from Lower Ferry Road to Ten 

Mile Lock.

Turbidity increased locally 

downstream from influent streams or outfalls 

and was not transported appreciable distances 

because of the low average velocities of water 

in the canal reaches from Lower Ferry Road to 

the Route18 Spillway, which ranged from 

0.45 to 0.22 ft/s. Turbidity that entered the 

feeder part of the canal from Raven Rock to 

Lower Ferry Road probably was transported 

greater distances than in the rest of the canal 

because the average velocity, 0.9 ft/s, was at 

least twice that in the rest of the canal.

In the reach between Ten Mile Lock 

and the Route 18 Spillway, little change was 

measured in the continuously monitored 

turbidity, which decreased less than 0.5 NTU 

for the mean and median during 1998-99. If 

no additional turbidity was introduced in the 

reach between Ten Mile Lock and the Route 

18 Spillway, a reduction of approximately 

4 NTU, which is similar to that in the reach 

between Griggstown and Ten Mile Lock, 

would be expected. The lack of a reduction in 

turbidity values for the reach between Ten 

Mile Lock and the Route 18 Spillway is not 

consistent with the average velocity for this 

reach, which is the lowest average velocity of 

all the reaches. Field observation of a sand bar 

immediately downstream from the confluence 

of Als Brook and the canal confirmed that the 

Als Brook drainage basin has contributed 

sediment carried by stormwater to the canal; 

the storm water and suspended solids could 

reach the monitor at the Route 18 Spillway 

and the raw water intakes for two drinkingwater treatment plants.
38

REFERENCES CITED

Burkhardt, M.R., Kammer, J.A., Jha, V.K., 

O’Mara, P.G., and Woodworth, M.T., 

1997, Methods of analysis by the 

U.S. Geological Survey National 

Water Quality LaboratoryDetermination of nonpurgeable 

suspended organic carbon by wetchemical oxidation and infrared 

spectroscopy: U.S. Geological Survey 

Open-file Report 97-380, 12 p.

Camp Dresser and McKee, Inc., 1986, 

Feasibility study to eliminate 

stormwater from the U.S. 1 conduit in 

the City of Trenton, New Jersey: 

Edison, N.J., Camp Dresser and 

McKee Inc., miscellaneous pagination.

Connor, B.F., Rose, D.L., Noriega, M.C., 

Murtagh, L.K., and Abney, S.R., 1998, 

Methods of analysis by the 

U.S. Geological Survey National 

Water Quality LaboratoryDetermination of 86 volatile organic 

compounds in water by gas 

chromatography/mass spectrometry, 

including detections less than reporting 

limits: U.S. Geological Survey OpenFile Report 97-829, 78 p.

Daniel, W.W., 1990, Applied Nonparametric 

Statistics, (2nd ed.): Boston, Mass., 

PWS-Kent Publishing Company, 

p. 226-233.

Delaware and Raritan Canal Commission, 

1977, Delaware and Raritan Canal 

State Park, master plan, adopted May 

1977: Delaware and Raritan Canal 

Commission, New Jersey Department 

of Environmental Protection, 83 p.

Deluca, M.J., Romanok, K.M., Riskin, M.L., 

Mattes, G.L., Thomas, A.M., and 

Gray, B.J., 2000, Water resources data 

for New Jersey-Water Year 1999, 

volume 3, Water-quality data: 

U.S. Geological Survey Water-Data 

Report NJ 99-3, 517 p.

Eaton, A.D., Clesceri, L.S., and Greenberg, 

A.E., eds., 1998, Standard methods for 

the examination of water and 

wastewater (20th ed.): Washington, 

D.C., American PublicHealth 

Association, 1111 p.

Ebasco Services, Inc., 1988, A study of the 

feasibility of controlling inflows of 

stormwater and sediment into the 

feeder canal, final report, volume 1: 

executive summary: Lyndhurst, N.J., 

Ebasco Services, Inc., 23 p.

Ellis, W.H., and Price, C.V., 1995, 

Development of a 14-digit hydrologic 

coding scheme and boundary data set 

for New Jersey: U.S. Geological 

Survey Water-Resources 

Investigations Report 95-4134, 1 pl.

Hay, L.E., and Campbell, J.P., 1990, Water 

quality trends in New Jersey streams: 

U.S. Geological Survey WaterResources Investigations Report

90-4046, 295 p.

Helsel, D.R., and Hirsch, R.M., 1992, 

Statistical methods in water resources: 

Amsterdam, The Netherlands, Elsevier 

Science Publishers B.V., 529 p.

Hem, J.D., 1992, Study and interpretation of 

the chemical characteristics of natural 

water: U.S. Geological Survey Water 

Supply Paper 2254, 263 p.

Hickman, R.E., and Barringer, T.H., 1999, 

Trends in water quality of New Jersey 

streams, water years 1986-95: 

U.S. Geological Survey WaterResources Investigations Report

98-4204, 174 p.

National Atmospheric Deposition Program 

(NRSP-3)/National Trends Network 

(2000), Annual Data Summary for 

Site:NJ99(Washington Crossing): 

accessed on July 26, 2000, on the 

World Wide Web at URL http://

nadp.sws.uiuc.edu/nadpdata (NADP 

Program Office, Illinois State Water 

Survey, 2204 Griffith Drive, 

Champaign, IL 61820).
39

New Jersey Department of Environmental 

Protection, 1996, New Jersey 

Geographic Information System CDROM Series1, volumes 2 and 3: New 

Jersey Department of Environmental 

Protection.

Radtke, D.B., Davis, J.V., and Wilde, F.D., 

1998, Specific electrical conductance, 

in Wilde, F.D., and Radtke, D.B., eds., 

1998, National field manual for the 

collection of water-quality data: 

U.S. Geological Survey Techniques of 

Water-Resources Investigations, book 

9, chap. A6, p. sc-22.

Rutgers University, 1980, A report on the 

investigation of hydrologic, hydraulic, 

water quality, and operational 

characteristics of the Delaware and 

Raritan Canal: College of Engineering, 

Cook College, Rutgers, The State 

University, N.J., miscellaneous 

pagination.

_____ 1981, A report on the dredging of the 

Delaware and Raritan Canal-a program 

plan and a programmatic 

environmental impact assessment: 

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Rutgers, The State University, N.J., 

miscellaneous pagination.

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New Jersey surface water resources, in

Moody, D.W., Chase, E.B., and 

Aronson, D.A., eds., National Water 

Summary 1985: U.S. Geological 

Survey Water Supply Paper 2300, 

p. 335-340.

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Interpreting drinking water quality 

analysis: What do the numbers mean?, 

(5th ed.), E214, Cook College, 

Rutgers, The State University, 63 p.

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changes for volatile organic 

compounds (Schedule 2020/2021), 

inductively coupled plasma-atomic 

emission spectrometry (ICP-AES), 

ammonia plus organic nitrogen and 

phosphorus (micro-Kjeldahl), in Water 

methods at the National Water Quality 

Laboratory: U.S. Geological Survey 

NWQL Technical Memorandum 

98.07, 7 p.

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Program, accessed on May 26, 2000, at 

URL http:// mapping.usgs.gov/www/

ndop/ index.html 

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Iwatsubo, R.T., 1998, Processing of 

water samples, in Wilde, F.D., Radtke, 

D.B., Gibs, Jacob, and Iwatsubo, R.T., 

eds., National field manual for the 

collection of water-quality data: 

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Water-Resources Investigations, book 

9, chap. A5, 128 p.

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UPG Multi-parameter water-quality 

instruction manual: Yellow Springs, 

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125 p.
40

APPENDIX A. RELATIONAL DATABASE DESIGN

INTRODUCTION

The CanalDB data model is described 

in this section. A complete listing of all table 

definitions and field properties and definitions 

in the CanalDB database is presented in a 

Data Dictionary. The Data Dictionary is the 

primary reference for the tables and fields in 

the Access database. A entity-relationship 

diagram of the data model also is presented 

(fig. A1). Together, the diagram and the Data 

Dictionary serve as the documentation for the 

database.

The following statement summarizes 

the water-quality data model: Sites may have 

one or more Samples, and Samples may have 

one or more Results. The core tables in 

CanalDB are the three tables that physically 

represent that statement (figs. A1 and A2), and 

each has a prefix of tbl: tblSite, tblSample, 

and tblResult (tables A1, A2, A3, 

respectively). All other tables in the database 

are used to provide classification and 

qualification information to the core tables; 

these are referred to as domain tables because 

each supplies information about (or selection 

lists for) a particular subject domain (for 

example, method, equipment, or parameter). 

There are ten domain tables in CanalDB, and 

all have a prefix of tds. Seven of these tables 

serve the tblSample core table 

(tdsHydrologicEvent, 

tdsHydrologicCondition, tdsSampleMedium, 

tdsSamplingMethod, tdsSamplingEquipment, 

tdsSamplingIntervalGroup and 

tdsSampleType; tables A4-A10, respectively), 

two serve the tblResult core table 

(tdsParameter and tdsResultFlag; tables A11 

and A12), and one (tdsAgency; table A13) 

serves both of those core tables by providing 

selections for sample collection and resultreporting agencies.

CORE ENTITIES IN THE

DATABASE

Site

A Site is defined as the place or 

location where Samples were collected. For 

each Site, data can include the official USGS 

Station name, Station ID (STAID), latitude, 

longitude, New Jersey State Plane coordinates 

(NJSP83), watershed code (HUC), and a 

comment.

Sample

A Sample is generally considered to be 

either field data (for example, stage level or 

temperature) or material (water specimen) 

collected at a single Site on a particular date 

and time. Samples are explicitly defined 

within CanalDB as a unique combination of 

site, date/time, collection agency, sample 

medium, sampling method, sampling 

equipment, and sample type (for example, 

regular, spike, or replicate). Each Sample is 

also classified to a “sampling interval group” 

that informs the user about whether the 

Sample is part of a series, for example 15-

minute-interval data from a continuous 

monitoring station. Sampling also is 

associated with (but not defined by) 

hydrologic events (for example, storm or 

hurricane) and hydrologic conditions (for 

example, rising stage of a storm event). 

Figures A1 and A2 illustrate how Samples and 

the associated domain tables fit into the 

model.

Result

A Result is the field measurement or 

laboratory analytical value pertaining to a 

single Parameter in a single Sample. In this 

appendix, Parameter refers to a characteristic 

or constituent. Each Sample can have many 

Results, but each Parameter can occur only 

once within a single Sample (for example, pH 

measured twice must be for different times or 
41

tblResult

Result for a specific parameter in a sample from a field measurement or a laboratory analytical process

tblSample

Sample of field data or collected material at a particular site and time characterized by medium, method, equipment, and sample type

tblSite

Site or place where samples were collected

tdsAgency

List of agencies or parties associated with the collection or analysis of a sample

tdsHydrologicCondition

List of hydrologic conditions under which sampling can be done

tdsHydrologicEvent

List of hydrologic event types for which sampling can be done tdsParameter

List of parameters (characteristics or constituents) for which result measurements or estimates were made in

a sample

tdsResultFlag

List of flags for the qualification of individual parameter results

tdsSampleMedium

List of media from which samples can be collected

tdsSampleType

List of types of samples that can be collected for a specific purpose

tdsSamplingEquipment

List of equipment used for sampling

tdsSamplingIntervalGroup

List of sampling intervals which can classify a sample as part of a group

tdsSamplingMethod

List of procedural methods used to obtain a sample

Prefix for coredata tablesPrefix fordomain tables

tbl

tds

Indicates the parenttable in a relationshipIndicates the child table in a relationship

EXPLANATION

Figure A1. Data model for Delaware and Raritan Canal water-quality database (CanalDB) showing definitions for each table and their relationships.

41
42

tdsResultFlag

ResultFlag_ID: IntegerResultFlag: Text(5)ResultFlagDescr: Text(75)

tdsSamplingIntervalGroup

SamplingIntervalGroup_ID: IntegerSamplingIntervalGroup: Text(50)SamplingIntervalGroupDescr: Text(75)

tdsHydrologicCondition

HydrologicCondition_ID: IntegerHydrologicConditionCode: Text(20)HydrologicCondition: Text(20)

tdsSampleType

SampleType_ID: IntegerSampleTypeCode: Text(1)SampleType: Text(20)

tdsSamplingMethod

SamplingMethod_ID: IntegerSamplingMethodCode: Text(50)SamplingMethod: Text(50)

tdsParameter

Parameter_ID: IntegerPCode: Text(6)ParameterGroup: Text(18)FieldOrLab: Text(5)Parameter: Text(50)Units: Text(20)ParameterAbbrev: Text(10)ParameterDescr: Text(120)

tdsAgency

Agency_ID: IntegerAgencyAbbrev: Text(10)Agency: Text(50)AgencyContact: Text(50)AgencyCode: Text(50)

tblSite

Site_ID: AutoNumberSTAID: Text(15)SiteName: Text(50)NJSP83: Text(50)Latitude: Text(12)Longitude: Text(12)HUC: Text(14)SiteComment: Memo

tblSample

Sample_ID: AutoNumberSRowID: Text(50)Site_ID: Long Integer (FK)SampleDateTime: Date/TimeHydrologicEvent_ID: Integer (FK)HydrologicCondition_ID: Integer (FK)CollectingAgency_ID: Integer (FK)SampleMedium_ID: Integer (FK)SamplingMethod_ID: Integer (FK)SamplingEquipment_ID: Integer (FK)SamplingIntervalGroup_ID: Integer (FK)SampleType_ID: Integer (FK)SampleComment: Memo

tblResult

Result_ID: AutoNumberSample_ID: Long Integer (FK)AnalyzingAgency_ID: Integer (FK)Parameter_ID: Integer (FK)ResultFlag_ID: Integer (FK)Result: DoubleResultComment: Memo

tdsSamplingEquipment

SamplingEquipment_ID: IntegerSamplingEquipmentCode: Text(10)SamplingEquipment: Text(70)

tdsSampleMedium

SampleMedium_ID: IntegerSampleMediumCode: Text(1)SampleMedium: Text(40)

tdsHydrologicEvent

HydrologicEvent_ID: IntegerHydrologicEventCode: Text(1)HydrologicEvent: Text(20)

Prefix fordomain tablesForeign key fieldNumbers in parenthesesindicate text fieldmaximum number ofcharacters

(FK)

tbl

tds

(20)

Figure A2. Structure of the Delaware and Raritan Canal water-quality database (CanalDB) showing fields in each table andselected properties (data type, text field size, foreign key designation (FK)).

Indicates the parenttable in a relationshipIndicates the child table in a relationshipPrefix for coredata tables

EXPLANATION
43

sample types, collection agency, or method as 

defined for a different Sample). Results are 

further qualified by association with a Result 

Flag (for example, < or estimated) to aid in 

interpreting the integrity and accuracy of the 

reported value. Figures A1 and A2 illustrate 

how Results fit into the model.

Summary Table

At the writing of this report (March 

2000), the CanalDB contains 10 Site records, 

267,061 Sample records, and 766,711 Result 

records. Because most of the Samples/Results 

are 15-minute or 30-minute-interval 

continuous monitoring data, a new table, 

tblDailySummary (table A14) was created to 

summarize individual Parameters at a Site 

throughout a day. A total of 12,340 daily 

statistics (number of measurements (N), 

minimum, maximum, and mean) for 

individual parameters are stored in the table to 

allow efficient browsing. The reduction from 

766,711 Result records to 12,340 summary 

records is due to compacting all 15-minute (N 

= 96 per day) and 30-minute (N = 48 per day) 

continuous monitoring data for each day. 

Measurements that are not part of a 

continuous series (instantaneous samples) are 

represented by a sample size (N) of 1.

The table tblDailySummary contains 

17 identification/classification fields and 4 

summary statistics fields (fig. A3). It is better 

suited to general browsing and queries of the 

data than is the individual Results table. It is 

also a more efficient link for Geographic 

Information Systems to display summarized 

values for spatial evaluation of parameters.

DATA DICTIONARY

The Data Dictionary is a listing of 

table and field properties for the CanalDB. 

Information about each table is shown in a 

heading area at the top of the table:

• Table Name is self explanatory.

• #Fields is the number of fields in the 

table.

• #Recs is the current number of records 

at the time the dictionary was 

generated.

• Last Updated is the date of last update 

to the table at the time the dictionary 

was generated.

• Table Description is a description of 

the table contents or function.

Below the heading area, a numbered 

listing of each field in the table is 

accompanied by descriptive information:

• Field Name is self explanatory.

• PK is checked if the field is part of the 

primary key for the table.

Figure A3. Fields in the table

tblDailySummary and their 

data types.

Site_ID: Long Integer

STAID: Text

SiteName: Text

SampleDate: Date/Time

CollectingAgency: Text

HydrologicEvent: Text

HydrologicCondition: Text

SampleMedium: Text

SamplingMethod: Text

SamplingEquipment: Text

SamplingIntervalGroup: Text

SampleType: Text

AnalyzingAgency: Text

ParameterGroup: Text

FieldOrLab: Text

Parameter: Text

Units: Text

N: Long Integer

Minimum: Double

Maximum: Double

Mean: Double

tblDailySummary
44

• FK is checked if the field is a foreign 

key pointing to data in a “parent” 

table.

• Rqd is checked if the field is required 

to have a value for each record in the 

table; if unchecked the field is 

optional.

• Type is the data type of the field.

• Size is the size of the field (maximum 

number of characters for text fields; 

for other data types, it represents the 

number of bytes used for storage).

• Default is the default value for the 

field (usually refers to a foreign key 

value that represents a selection from a 

domain table).

• Description is a description of the 

field.
45

tblSite

Table Description:

#Fields

Field Name Type Size Description

8

Site or place where samples were collected

Table Name

PK Rqd

#Recs

10

Last Updated:

11/20/00 8:32:09 A

FK Default

1 Site_ID AutoNumber 

(Long)

4 Key that uniquely 

identifies a site (place) 

where sampling occurs

3 STAID Text 15 USGS site identification 

code

4 SiteName Text 50 Name by which site is 

known

5 NJSP83 Text 50 New Jersey State 

Projection 1983 

coordinate for site 

location

6 Latitude Text 12 Latitude in degreesminutes-seconds format

7 Longitude Text 12 Longitude in degreesminutes-seconds format

8 HUC Text 14 14-digit hydrologic unit 

code that identifies the 

watershed in which a site 

is located

9 SiteComment Memo - Comment about a site

Table A-1. Characteristics of tblSite
46

tblSample

Table Description:

#Fields

Field Name Type Size Description

13

Sample of field data or collected material at a particular site and time 

characterized by medium, method, equipment, and sample type

Table Name

PK Rqd

#Recs

267061

Last Updated:

11/20/00 8:31:47 A

FK Default

1 Sample_ID AutoNumber 

(Long)

4 Key that uniquely 

identifies an individual 

sample of data or material

2 SRowID Text 50 Code representing the 

source and row number 

from the original USGS 

National Water 

Information System 

import file

3 Site_ID Number (Long) 4 Key that uniquely 

identifies a site (place) 

where sampling occurs

4 SampleDateTime Date/Time 8 Date and time at which a 

sample was collected, in 

the format yyyy-mm-dd 

hh:mm:ss

5 HydrologicEvent_ID Number (Integer) 2 Key that uniquely 

identifies a hydrologic 

event

0

6 HydrologicCondition_ID Number (Integer) 2 Key that uniquely 

identifies a hydrologic 

condition

0

7 CollectingAgency_ID Number (Integer) 2 Key that uniquely 

identifies an agency 

involved in collecting or 

analyzing samples

8 SampleMedium_ID Number (Integer) 2 Key that uniquely 

identifies a medium 

which is sampled

9

Table A-2. Characteristics of tblSample
47

9 SamplingMethod_ID Number (Integer) 2 Key that uniquely 

identifies a sampling 

method used to collect

a sample or make a

measurement

10 SamplingEquipment_ID Number (Integer) 2 Key that uniquely 

identifies a type of 

equipment used for 

sampling

11 SamplingIntervalGroup_ID Number (Integer) 2 Key that uniquely 

identifies a sampling 

interval group

12 SampleType_ID Number (Integer) 2 Key that uniquely 

identifies a sample type

9

13 SampleComment Memo - Comment about a sample

that assists with 

evaluating results

Table A-2. Characteristics of tblSample--continued
48

tblResult

Table Description:

#Fields

Field Name Type Size Description

7

Result for a specific parameter in a sample from a field measurement 

or a laboratory analytical process

Table Name

PK Rqd

#Recs

766711

Last Updated:

11/20/00 9:36:52 A

FK Default

1 Result_ID AutoNumber 

(Long)

4 Key that uniquely 

identifies a result of 

measurement or analysis 

for a single parameter 

from a sampling event

2 Sample_ID Number (Long) 4 Key that uniquely 

identifies an individual 

sample of data or material

3 AnalyzingAgency_ID Number (Integer) 2 Key that uniquely 

identifies an agency 

involved in collecting or 

analyzing samples

4 Parameter_ID Number (Integer) 2 Key that uniquely 

identifies a parameter 

(characteristic or 

constituent)

5 ResultFlag_ID Number (Integer) 2 Key that uniquely 

identifies a ResultFlag 

qualifying a result

0

6 Result Number (Double) 8 Result (value) for a 

parameter from a field 

measurement or 

laboratory analysis of a 

sample

7 ResultComment Memo - Comment for a result to 

provide information 

about a value not covered

by other result qualifiers

Table A-3. Characteristics of tblResult
49

tdsHydrologicEvent

Table Description:

#Fields

Field Name Type Size Description

3

List of hydrologic event types for which sampling can be done

Table Name

PK Rqd

#Recs

14

Last Updated:

11/20/00 9:05:31 A

FK Default

1 HydrologicEvent_ID Number (Integer) 2 Key that uniquely 

identifies a hydrologic 

event

2 HydrologicEventCode Text 1 USGS code used to 

identify a hydrologic 

event

3 HydrologicEvent Text 20 Hydrologic event name

Table A-4. Characteristics of tdsHydrologicEvent
50

tdsHydrologicCondition

Table Description:

#Fields

Field Name Type Size Description

3

List of hydrologic conditions under which sampling can be done

Table Name

PK Rqd

#Recs

7

Last Updated:

11/20/00 8:32:40 A

FK Default

1 HydrologicCondition_ID Number (Integer) 2 Key that uniquely 

identifies a hydrologic 

condition

2 HydrologicConditionCode Text 20 USGS code used to 

identify a hydrologic 

condition

3 HydrologicCondition Text 20 Description of a 

hydrologic condition

Table A-5. Characteristics of tdsHydrologicCondition
51

tdsSampleMedium

Table Description:

#Fields

Field Name Type Size Description

3

List of media from which samples can be collected

Table Name

PK Rqd

#Recs

35

Last Updated:

11/20/00 9:38:12 A

FK Default

1 SampleMedium_ID Number (Integer) 2 Key that uniquely 

identifies a medium 

which is sampled

2 SampleMediumCode Text 1 USGS code used to 

identify a sample medium

3 SampleMedium Text 40 Sample medium name

Table A-6. Characteristics of tdsSampleMedium
52

tdsSamplingMethod

Table Description:

#Fields

Field Name Type Size Description

3

List of procedural methods used to obtain a sample

Table Name

PK Rqd

#Recs

9

Last Updated:

11/20/00 8:35:17 A

FK Default

1 SamplingMethod_ID Number (Integer) 2 Key that uniquely 

identifies a sampling 

method used to take a 

sample or make a 

measurement

2 SamplingMethodCode Text 50 USGS code used to 

identify a sampling 

method

3 SamplingMethod Text 50 Sampling method 

description

Table A-7. Characteristics of tdsSamplingMethod
53

tdsSamplingEquipment

Table Description:

#Fields

Field Name Type Size Description

3

List of equipment used for sampling

Table Name

PK Rqd

#Recs

114

Last Updated:

11/20/00 8:34:40 A

FK Default

1 SamplingEquipment_ID Number (Integer) 2 Key that uniquely 

identifies a type of 

equipment used for 

sampling

2 SamplingEquipmentCode Text 10 USGS code used to 

identify equipment used 

for sampling

3 SamplingEquipment Text 70 Equipment used for 

sampling

Table A-8. Characteristics of tdsSamplingEquipment
54

tdsSamplingIntervalGroup

Table Description:

#Fields

Field Name Type Size Description

3

List of sampling intervals which can classify a sample as part of a group

Table Name

PK Rqd

#Recs

4

Last Updated:

11/20/00 9:38:41 A

FK Default

1 SamplingIntervalGroup_ID Number (Integer) 2 Key that uniquely 

identifies a sampling 

interval group

2 SamplingIntervalGroup Text 50 Sampling interval group 

name

3 SamplingIntervalGroupDescr Text 75 Sampling interval group 

description

Table A-9. Characteristics of tdsSamplingIntervalGroup
55

tdsSampleType

Table Description:

#Fields

Field Name Type Size Description

3

List of types of samples that can be collected for a specific purpose

Table Name

PK Rqd

#Recs

12

Last Updated:

11/20/00 8:34:27 A

FK Default

1 SampleType_ID Number (Integer) 2 Key that uniquely 

identifies a sample type

2 SampleTypeCode Text 1 USGS code used to 

identify a sample type

3 SampleType Text 20 Sample type name

Table A-10. Characteristics of tdsSampleType
56

tdsParameter

Table Description:

#Fields

Field Name Type Size Description

8

List of parameters (characteristics or constituents) for which result 

measurements or estimates were made in a sample

Table Name

PK Rqd

#Recs

61

Last Updated:

11/21/00 11:50:56 

FK Default

1 Parameter_ID Number (Integer) 2 Key that uniquely 

identifies a parameter 

(characteristic or 

constituent)

2 PCode Text 6 USGS code used to 

identify a specific 

parameter in the National

Water Information System

3 ParameterGroup Text 18 Group to which a 

parameter belongs (such 

as nutrient)

4 FieldOrLab Text 5 Identifies whether a 

parameter value is 

determined in the field or

in a laboratory

5 Parameter Text 50 Name of parameter

6 Units Text 20 Reporting units for a 

result of a parameter 

measurement or 

laboratory analysis

7 ParameterAbbrev Text 10 Parameter abbreviation

8 ParameterDescr Text 120 Parameter description

Table A-11. Characteristics of tdsParameter
57

tdsResultFlag

Table Description:

#Fields

Field Name Type Size Description

3

List of flags for the qualification of individual parameter results

Table Name

PK Rqd

#Recs

10

Last Updated:

11/20/00 8:33:47 A

FK Default

1 ResultFlag_ID Number (Integer) 2 Key that uniquely 

identifies a ResultFlag 

qualifying a result

2 ResultFlag Text 5 Flag used to qualify a 

parameter result

3 ResultFlagDescr Text 75 Description of flag used 

to qualify a parameter 

result

Table A-12. Characteristics of tdsResultFlag
58

tdsAgency

Table Description:

#Fields

Field Name Type Size Description

5

List of agencies or parties associated with the collection or analysis of a 

sample

Table Name

PK Rqd

#Recs

5

Last Updated:

11/20/00 8:29:30 A

FK Default

1 Agency_ID Number (Integer) 2 Key that uniquely 

identifies an agency 

involved in collecting or 

analyzing samples

2 AgencyAbbrev Text 10 Agency abbreviation or 

code

3 Agency Text 50 Agency name

4 AgencyContact Text 50 Agency contact 

information

5 AgencyCode Text 50 USGS numeric code for 

an agency in the National

Water Information System

Table A-13. Characteristics of tdsAgency
59

tblDailySummary

Table Description:

#Fields

Field Name Type Size Description

21

Summary of daily values for each parameter at each site; this table is 

generated by a query and does not require integrity constraints which 

are already applied to the transactional database design

Table Name

PK Rqd

#Recs

12340

Last Updated:

11/21/00 11:50:56 

FK Default

1 Site_ID Number (Long) 4 Key that uniquely 

identifies a site (place) 

where sampling occurs

2 STAID Text 15 USGS site identification 

code

3 SiteName Text 50 Name by which site is 

known

4 SampleDate Date/Time 8 Date on which samples 

were collected

5 CollectingAgency Text 10 Abbreviation or code of 

an agency involved in 

collecting or analyzing 

samples

6 HydrologicEvent Text 20 Hydrologic event name

7 HydrologicCondition Text 20 Description of a 

hydrologic condition

8 SampleMedium Text 40 Sample medium name

9 SamplingMethod Text 50 Sampling method 

description

10 SamplingEquipment Text 70 Equipment used for 

sampling

11 SamplingIntervalGroup Text 50 Sampling interval group 

name

12 SampleType Text 20 Sample type name

13 AnalyzingAgency Text 10 Abbreviation or code of 

an agency involved in 

collecting or analyzing 

samples

Table A-14. Characteristics of tblDailySummary
60

14 ParameterGroup Text 18 Group to which a 

parameter belongs (such 

as nutrient)

15 FieldOrLab Text 5 Identifies whether a 

parameter value is 

determined in the field or

in a laboratory

16 Parameter Text 50 Name of parameter

17 Units Text 20 Reporting units for a 

result of a parameter 

measurement or 

laboratory analysis

18 N Number (Long) 4 Number of measurements

used in the daily 

summary statistics

19 Minimum Number (Double) 8 Minimum result value 

reported within the daily 

summary for a parameter

20 Maximum Number (Double) 8 Maximum result value 

reported within the daily 

summary for a parameter

21 Mean Number (Double) 8 Mean result value 

reported within the daily 

summary for a parameter

Table A-14. Characteristics of tblDailySummary--continued