Prepared in cooperation with the

New Jersey Department of Environmental Protection 

U.S. Department of the Interior

U.S. Geological Survey

Use of a Ground-Water Flow Model to Delineate

Contributing Areas to the Puchack Well Field,

Pennsauken Township and Vicinity, Camden County,

New Jersey

Scientific Investigations Report 2004-5101
Use of a Ground-Water Flow Model 

to Delineate Contributing Areas to the 

Puchack Well Field, Pennsauken Township 

and Vicinity, Camden County, New Jersey

By Daryll A. Pope and Martha K. Watt

Prepared in cooperation with the

New Jersey Department of Environmental Protection

Scientific Investigations Report 2004-5101

U.S. Department of the Interior

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

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2005

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

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endorsement by the U.S. Government.

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

reproduce any copyrighted materials contained within this report.
iii

Contents

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

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

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

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

Well-Numbering System ........................................................................... 3

Hydrogeology and Stratigraphy ........................................................................ 3

Model Development and Calibration .................................................................. 4

Aquifer-System Geometry and Model Grid ...................................................... 4

Boundary Conditions .............................................................................. 6

Recharge ....................................................................................... 6

Surface Water ................................................................................. 6

Lateral Model Boundaries .................................................................. 9

Ground-Water Withdrawal Data .................................................................. 9

Hydrogeologic Properties ........................................................................ 9

Horizontal Hydraulic Conductivity of Aquifers and Confining Units ..................... 9

Vertical Hydraulic Conductivity of Confining Units ....................................... 11

Model Calibration ................................................................................. 11

Calibration Criteria ........................................................................... 11

Simulation of January-March 1998 Conditions .......................................... 17

Contributing-Area Delineation ........................................................................... 17

Simulation of Flow System ........................................................................ 23

Particle Tracking .................................................................................... 23

Contributing Area ................................................................................. 23

Uncertainty Analysis .............................................................................. 26

Approach ....................................................................................... 26

Effects of Model-Input Parameter Values on Contributing Areas ..................... 26

Porosity ................................................................................. 26

Withdrawals ........................................................................... 26

Recharge ................................................................................. 38

Hydraulic Conductivity .................................................................. 38

Vertical Hydraulic Conductivity ...................................................... 38

Aggregate Contributing Area ..................................................................... 38

Summary ................................................................................................... 43

Acknowledgments ....................................................................................... 44

Literature Cited .......................................................................................... 44
iv

Figures

 1-29. Maps Showing—

 1. Location of the local model and ground-water withdrawal data for the 

 delineation simulation, Pennsauken Township and vicinity, Camden County, 

 New Jersey. .............................................................................. 2

 2. Ground-water flow model grid used for contributing-area delineation, and 

 outcrop areas of the Potomac-Raritan-Magothy aquifer system. .................. 5

 3. Recharge used in the ground-water flow model. .................................... 7

 4. Hydraulic conductivity of the riverbed material. .................................... 8

 5. Average ground-water withdrawals during January-March 1998 in the

 steady-state flow model. ............................................................... 10

 6. Horizontal hydraulic conductivity of the Lower aquifer of the

 Potomac-Raritan-Magothy aquifer system in the ground-water flow model. ... 12

 7. Vertical hydraulic conductivity in confining unit C-1 in the ground-water 

 flow model. .............................................................................. 14

 8. Vertical hydraulic conductivity in confining unit C-2a in the ground-water 

 flow model ................................................................................. 15

 9. Vertical hydraulic conductivity in confining unit C-2b in the ground-water 

 flow model ................................................................................. 16

 10. Location of wells used to calibrate vertical hydraulic conductivity in the

 ground-water flow model ............................................................... 18

 11. Simulated and measured potentiometric surfaces and residuals in the 

 Middle aquifer of the Potomac-Raritan-Magothy aquifer system, 

 January-March 1998. ..................................................................... 19

 12. Simulated and measured potentiometric surfaces and residuals in the 

 Lower aquifer of the Potomac-Raritan-Magothy aquifer system, 

 January-March 1998. ..................................................................... 20

 13. Differences between simulated and measured gradients across confining 

 units C-2a and C-2b, January-March 1998. ............................................. 21

 14. Simulated contributing area to the Puchack well field in the delineation 

 simulation ................................................................................. 24

 15. Simulated contributing area to individual wells in the Puchack well field ......... 25

 16. Simulated contributing area to Puchack well field when porosity is increased to 

 25 percent in aquifers and 30 percent in confining units. .............................. 28

 17. Simulated contributing area to Puchack well field when porosity is decreased 

 to 15 percent in aquifers and 20 percent in confining units. ........................ 29

 18. Simulated contributing area to Puchack well field when withdrawals at 

 the Morris/Delair well field are distributed in the northern part of the well field. 30

 19. Simulated contributing area to Puchack well field when withdrawals at 

 the Morris/Delair well field are distributed in the southern part of the well field 31

 20. Simulated contributing area to Puchack well field when recharge is 

 increased 29 percent. .................................................................. 32

 21. Simulated contributing area to Puchack well field when recharge is 

 decreased 32 percent. .................................................................. 33

 22. Simulated contributing area to Puchack well field when the hydraulic 

 conductivity of the Middle aquifer of the Potomac-Raritan-Magothy aquifer 

 system is increased 50 percent ......................................................... 34
v

 23. Simulated contributing area to Puchack well field when the hydraulic 

 conductivity of the Middle aquifer of the Potomac-Raritan-Magothy aquifer 

 system is decreased 28 percent. ...................................................... 35

 24. Simulated contributing area to Puchack well field when the hydraulic 

 conductivity of the Lower aquifer of the Potomac-Raritan-Magothy aquifer 

 system is increased 23 percent ......................................................... 36

 25. Simulated contributing area to Puchack well field when the hydraulic

 conductivity of the Lower aquifer of the Potomac-Raritan-Magothy aquifer 

 system is decreased 19 percent ...................................................... 37

 26. Simulated contributing area to Puchack well field when the vertical hydraulic

 conductivity of the Middle aquifer of the Potomac-Raritan-Magothy aquifer 

 system is increased 1,900 percent ...................................................... 39

 27. Simulated contributing area to Puchack well field when the vertical hydraulic

 conductivity of the Middle aquifer of the Potomac-Raritan-Magothy aquifer 

 system is decreased 78 percent. ...................................................... 40

 28. Number of model runs in which each area contributed flow to the Puchack 

 well field in the uncertainty analysis. ................................................... 41

 29. Simulated aggregate contributing area to the Puchack well field including 

 the effects of uncertainty analysis. ................................................... 42

Tables

1. Well-construction data for wells used in the ground-water flow model,

Pennsauken Township and vicinity, Camden County, New Jersey ..................... 45

2. Local hydrogeologic framework used in this study, corresponding model layers

used in the ground-water flow model, and comparison to the regional

hydrogeologic framework as described in previous studies ........................... 4

3. Ground-water withdrawal data used in the ground-water flow model ............... 11

4. Wells with aquifer-test data and estimates of hydraulic conductivity .................. 13

5. Simulated and measured head differences at nested wells. ........................... 22

6. Model runs and parameter changes in the ground-water flow model .................. 27
vi

Conversion Factors

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

Area

square foot (ft2) 0.09290 square meter (m2)

Volume

gallon (gal) 3.785 liter (L) 

Flow rate

gallon per minute (gal/min) 0.06309 liter per second (L/s)

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

Hydraulic conductivity

foot per day (ft/d) 0.3048 meter per day (m/d)

Transmissivity*

foot squared per day (ft2/d) 0.09290 meter squared per day (m2/d) 

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 

(NGVD of 1929).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Altitude, as used in this report, refers to distance above the vertical datum.
Abstract

The New Jersey Department of Environmental Protection (NJDEP) Well Head Protection Program, developed 

in response to the 1986 Federal Safe Drinking Water Act 

Amendments, requires delineation of Well Head Protection 

Areas (WHPA’s), commonly called contributing areas, for 

all public and non-community water-supply wells in New 

Jersey. Typically, WHPA’s for public community water-supply 

wells in New Jersey are delineated using a two-dimensional 

ground-water flow model incorporating the regional hydraulic 

gradient; however, NJDEP guidelines allow for the use of a 

three-dimensional flow model to delineate contributing areas 

to wells in complex hydrogeologic settings.

The Puchack well field in Pennsauken Township, 

Camden County, N.J., is an area of strong hydraulic 

connection between the Lower aquifer of the PotomacRaritan-Magothy aquifer system and the Delaware River. 

Interactions among and within the public-supply well fields in 

the area are complex.

To delineate the contributing area to the Puchack well 

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

NJDEP, developed an 11-layer ground-water flow model of the 

Potomac-Raritan-Magothy aquifer system in the Pennsauken 

Township area to simulate flow in the vicinity of the well field. 

The model incorporates the interaction between the aquifer 

system and the Delaware River, and includes boundary flows 

from an existing regional model of the Camden area. Recharge 

used in the model ranged from 4.5 to 14 inches per year, and 

horizontal hydraulic conductivity ranged from 50 to 250 feet 

per day. Values of vertical hydraulic conductivity ranging from 

0.001 to 0.5 feet per day were assigned to zones created on the 

basis of variations in hydrogeologic conditions observed in 

geophysical logs from wells.

A steady-state simulation was used to calibrate the model 

to synoptic water-level data collected in March 1998. Near 

the Puchack well field, simulated heads generally were within 

1 foot of the measured heads in both the Middle and Lower 

aquifers. Simulated water-level differences across the confining units at most of the nested wells were within ± 0.5 feet of 

the differences calculated from measured water levels.

The existing flow model was modified to meet NJDEP 

guidelines for delineating contributing areas in complex 

hydrogeologic settings. These modifications included rediscretizing the model grid to a finer grid and preparing the 

water-use data set for use in the rediscretized model. The 

contributing area to the Puchack well field was delineated by 

means of particle tracking. 

An uncertainty analysis was conducted in which 36 

model-input parameters were both increased and decreased 

until the resulting change in simulated heads exceeded the 

model-calibration criterion of ± 5 feet at any model cell. 

Porosity most affected the size and shape of the contributing area. The distribution of withdrawals at the Morris/Delair 

well field and variations in recharge affected both the size and 

shape of contributing area to the Puchack well field and the 

source of water to the Puchack wells. 

The results of the uncertainty analysis were combined to 

determine the “aggregate” contributing area to the Puchack 

well field—a composite of areas on the land surface that 

contributed flow to the Puchack well field in less than 12 years 

in any uncertainty simulation. The shape of the aggregate 

contributing area was most similar to that associated with a 

reduction in porosity, which indirectly affected the size and 

shape of the contributing areas by changing travel time.

Introduction

The 1986 Federal Safe Drinking Water Act Amendments 

(Section 1428, P.L. 93-523, 42 USC 300 et seq.) directed 

all States to develop a Well Head Protection Program for all 

public community and non-community water-supply wells. In 

1991, a Well Head Protection Program was approved in New 

Jersey that aims to prevent contamination of the ground-water 

resource, which provides drinking water to approximately 

Use of a Ground-Water Flow Model to Delineate 

Contributing Areas to the Puchack Well Field, 

Pennsauken Township and Vicinity, 

Camden County, New Jersey

By Daryll A. Pope and Martha K. Watt
42 percent of New Jersey’s population. Delineation of a Well 

Head Protection Area (WHPA), or the area from which a well 

draws its water within a specific time frame, is one aspect 

of the Well Head Protection Program. Areas designated as 

WHPA’s become a priority for efforts to prevent and mitigate 

ground-water contamination (Spayd and Johnson, 2003). 

The New Jersey Department of Environmental Protection (NJDEP) delineated WHPA’s for all water-supply wells in 

New Jersey. Each WHPA consists of three “tiers” representing 

the time of travel to the well. The travel times associated with 

each of the three tiers are shown below.

Tier 1 0 to 2 years

Tier 2 greater than 2 years to 5 years

Tier 3 greater than 5 years to 12 years

The NJDEP delineated WHPA’s (contributing areas) for 

public community water-supply wells using the “combined 

model/CFR method,” which combines a Calculated Fixed 

Radius (CFR) analysis and a two-dimensional flow model. 

The CFR analysis defines a radius around the well on the basis 

of pumping rate, time of travel, effective porosity, and aquifer 

thickness. The “combined model/CFR method” combines the 

CFR analysis with a two-dimensional flow model to incorporate the hydraulic gradient, aquifer transmissivity, saturated 

thickness, and anisotropy. The State guidelines also allow, 

however, for the use of a three-dimensional ground-water 

flow model (an “advanced delineation”) in areas where 

hydrologic conditions are complex (Spayd and Johnson, 

2003), such as the Pennsauken Township area in Camden 

County, N.J. (fig. 1). 

39

40

41

75 74

Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 02’ 30" 75

40

00’

39

57’

30"

75

05’

75

02’

30"

Camden City

Palmyra

Borough

Cinnaminson Township

Delaware River

New Jersey

Pennsylvania

Merchantville-Pennsauken

Water Company

Browning well field

Merchantville-Pennsauken

Water Company

National Highway well field

Merchantville-Pennsauken

Water Company

Marion well field 

Merchantville-Pennsauken

Water Company

Park Avenue well field

City of Camden

Delair well field

Merchantville-Pennsauken

Water Company

Woodbine well field

Pennsauken

Township

Merchantville

Borough

Maple

Shade

Township

Cherry

Hill

Township

Burlington County

Camden County

40 00’

0 375 750 1,500 METERS

0 0.5 1 MILE

0 25 50 MILES

0 25 50 KILOMETERS

NEW JERSEY

Coastal Plain

Local

model area

Fall Line

Pe nnsauken Creek

Philadelphia

Trenton

City of Camden

Morris/Delair

well field

City of Camden

Puchack well field

EXPLANATION

GROUND-WATER WITHDRAWALS--

in million gallons per year

0 to 100

Greater than 100 to 200

Greater than 200 to 300

Greater than 300 to 365

Regional

model area

Figure 1. Location of the local model and ground-water withdrawal data for the delineation simulation, Pennsauken Township and 

vicinity, Camden County, New Jersey.

2 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
The Potomac-Raritan-Magothy aquifer system has been 

an important source of water supply in northwestern Camden 

County for many years. In the Pennsauken Township area, this 

aquifer system is the source of potable water to the City of 

Camden and the Merchantville-Pennsauken Water Company. 

As part of the effort to maintain the quality of the water supply, the U.S. Geological Survey (USGS), in cooperation with 

the NJDEP, delineated the contributing area to the Puchack 

well field using a three-dimensional ground-water flow model. 

Purpose and Scope

This report documents the delineation of the contributing 

area to the Puchack well field in Pennsauken Township, New 

Jersey, using a three-dimensional ground-water flow model. 

Hydrogeology, stratigraphy, and hydraulic properties of the 

Potomac-Raritan-Magothy aquifer system are described, and 

ground-water withdrawal data and estimates of ground-water 

recharge rates are presented. The report describes the approach 

used to calibrate the flow model and the results of the model 

calibration. The flow model was calibrated using water levels 

measured in March 1998 at 78 wells and vertical differences 

in water levels measured in 15 nests of wells completed in 

different aquifers. The flow model is used to delineate the contributing area to the Puchack well field using particle-tracking analysis that calculates the travel times of water to wells. 

Contributing areas with travel times of 2, 5, and 12 years were 

estimated and the effects of variability in model parameters on 

the contributing-area size and shape were evaluated. Thirty-six 

model runs were done in which parameters such as porosity, 

hydraulic conductivity, and recharge were systematically varied until simulated water levels changed 5 ft from calibrated 

values. Results of uncertainty analysis, done to test the sensitivity of the model and obtain conservative estimates of the 

contributing areas to the wells, are used to create an aggregate 

contributing area for the Puchack well field (a composite of 

areas on the land surface that contributed flow to the Puchack 

well field in less than 12 years in any uncertainty simulation).

Previous Investigations

The hydrogeologic framework of the Coastal Plain and 

ground-water flow in the vicinity of Pennsauken Township are 

described in several regional studies. Zapecza (1989) describes 

the hydrogeologic framework of the New Jersey Coastal 

Plain. Martin (1998) describes ground-water flow in the New 

Jersey Coastal Plain. Farlekas and others (1976) describe the 

hydrogeology of Camden County. Navoy and Carleton (1995) 

describe the hydrogeology of the Camden County area and 

present a simulation of the regional ground-water-flow system 

that provides lateral and vertical boundary flows for the local 

model described in this report. Walker and Jacobsen (2004) 

present the stratigraphy of the Pennsauken area along with 

water-level and water-quality data. 

Well-Numbering System

The well-numbering system used in this report consists of 

a county-code number followed by a sequence number of the 

well within the county. County codes used in this report are 5 

for Burlington County and 7 for Camden County. For example, well number 7-528 represents the 528th well inventoried 

in Camden County. Construction details for wells referred to 

in this report are shown in table 1 (at the end of the report).

Hydrogeology and Stratigraphy

The Potomac-Raritan-Magothy aquifer system is composed of the wedge-shaped sequence of Cretaceous sediments 

that make up the Potomac Group and the Raritan and Magothy 

Formations. These sediments constitute sand and gravel aquifers with intervening silt and clay confining units that thicken 

and dip from the western edge of the Coastal Plain at the Fall 

Line toward the southeast (Zapecza, 1989). The sediments are 

of fluvial-deltaic-marginal marine origin (Farlekas and others, 

1976) and represent a complex depositional and erosional 

environment. The basal unit of the Potomac Group lies directly 

on the erosional, pre-Cretaceous bedrock surface.

The hydrogeology and stratigraphy of the PotomacRaritan-Magothy aquifer system in the study area as described 

in detail by Walker and Jacobsen (2004) are compared to the 

previously described hydrogeologic framework of the Coastal 

Plain (Navoy and Carleton, 1995; Zapecza, 1989; Farlekas and 

others, 1976) in table 2. 

In previous studies of the area, the Potomac-RaritanMagothy aquifer system has been described as consisting of 

the Upper, Middle, and Lower aquifers and two intervening 

confining units (table 2). The Upper aquifer consists of sands 

of the Magothy Formation, and the Middle and Lower aquifers 

are composed of sands of the Raritan Formation and Potomac 

Group. These sediments crop out as thin bands along both 

sides of the Delaware River in Pennsylvania and New Jersey 

and are exposed in the bed of the Delaware River through fluvial dissection and dredging (fig. 2). In downdip areas to the 

east, the aquifer system is overlain the Merchantville-Woodbury confining unit. 

In Pennsauken Township and vicinity, permeable layers 

of sand and gravel that make up the Pennsauken Formation 

and Quaternary deposits cap the outcrops of the Cretaceous 

sediments that form the Potomac-Raritan-Magothy aquifer 

system (Farlekas and others, 1976) throughout most of their 

extent. Sands and gravels of the Pennsauken Formation are 

believed to have been deposited in a fluvial environment in 

which a series of downcutting channels were incised into 

the underlying sediments (Owens and Minard, 1979). The 

Quaternary deposits grade from gravel and gravelly sand at 

Trenton, N.J., to clayey silt at Philadelphia, Pa.; the differences 

in these sediments probably represent a change in depositional 

environment. The Tertiary and Quaternary surficial units are 

Hydrogeology and Stratigraphy 3
hydraulically connected to the underlying Cretaceous sediments and, therefore, are considered to be part of the PotomacRaritan-Magothy aquifer system.

Because of the depositional environment of the sediments 

that comprise the aquifer system, discontinuities in individual 

units are common. Throughout the thickness of the Cretaceous 

sediments, channels have been cut and filled. Thus, major 

confining units can contain sand lenses that are local waterbearing zones, and aquifers can contain clay lenses that serve 

as local confining units. Major confining units also pinch out 

in some areas. As a result, the hydraulic connections among 

the sedimentary units can be complex.

Model Development and Calibration

A three-dimensional, finite-difference ground-water 

flow model was used to simulate ground-water flow in the 

Potomac-Raritan-Magothy aquifer system in Pennsauken 

Township and surrounding areas. The ground-water flow 

system was simulated using the USGS modular model 

MODFLOW-96, developed by Harbaugh and McDonald 

(1996). The Flow and Head Boundary (FHB1) Package 

(Leake and Lilly, 1997) was used to input the boundary 

flows from a regional model of the Camden area (Navoy and 

Carleton, 1995). For this report, the flow model (fig. 1) was 

calibrated using average-withdrawal data for January-March 

1998 and water levels measured in March 1998. 

Aquifer-System Geometry and Model Grid

Walker and Jacobsen (2004) subdivided the hydrogeologic framework of the Potomac-Raritan-Magothy aquifer 

system into a detailed 11-layer framework for use in the local 

ground-water flow model. The most important differences 

between this detailed framework and the regional 5-layer 

framework included modifications to the representation of the 

confining unit between the Middle and Lower aquifers and differences in the variability of hydraulic properties in the Lower 

aquifer. The uppermost unit (A-1) represents the Upper aquifer 

of the Potomac-Raritan-Magothy aquifer system and generally corresponds to the sand of the Magothy Formation and 

the overlying Miocene and Pleistocene deposits. The Upper 

aquifer is modeled as unconfined in its outcrop area (fig. 2). 

Where the Upper aquifer is overlain by the MerchantvilleWoodbury confining unit, it is modeled as a confined aquifer. 

Because the units dip, all of the layers have both unconfined 

and confined areas. In MODFLOW, only the uppermost layer 

can be modeled as unconfined (transmissivity varies with 

water level); therefore, the Upper aquifer is modeled in this 

manner. All other layers are modeled as confined units. Where 

these units crop out, they are modeled, wherever possible, as 

unconfined units, either by specifying appropriate recharge 

values or applying river boundaries along with storage factors 

that reflect unconfined conditions (specific yield). The effect 

of fixed transmissivity in the outcrop areas of these other units 

is considered to be negligible because changes in water levels 

are small compared to the model layer thicknesses. 

Table 2. Local hydrogeologic framework used in this study, corresponding model layers used in the groundwater flow model, and comparison to the regional hydrogeologic framework as described in previous studies, 

Pennsauken Township and vicinity, Camden County, New Jersey.

Previously described 

framework 

(5 layers)1

Framework (11 layers) used in the ground-water flow model in this report

Hydrogeologic unit Model layer Model-layer 

designation

Model-layer 

number Major hydrogeologic unit

Upper aquifer Aquifer A-1 1 Upper aquifer

Confining unit Confining unit C-1 2 Confining unit

Middle aquifer

Upper sand A-2a 3

Interbedded confining unit A-2c1 4 Middle aquifer

Lower sand A-2b 5

Confining unit

Upper confining unit C-2a 6 Confining unit

Intermediate sand C-2AI 7

Lower aquifer

Lower confining unit C-2b 8

Lower aquifer

Upper zone A-3a 9

Middle zone A-3b 10

Lower zone A-3c 11

Bedrock confining unit Bedrock confining unit Underlying clay or bedrock

1

Navoy and Carleton, 1995; Zapecza, 1989; and Farlekas and others, 1976.

4 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 02’ 30" 40 00’ 75 00’

40

00’

39

57’

30"

75

05’

75

02’

30"

Pennsauken

Township

Merchantville

Borough

Camden City

Cherry

Hill

Township

Palmyra

Borough

Cinnaminson Township

Maple

Shade

Township

Delaware River

Pennsylvania

New Jersey

Camden County

Burlington County

ROWS

COLUMNS

EXPLANATION

OUTCROP AREA OF THE POTOMACRARITAN-MAGOTHY AQUIFER SYSTEM

Puchack well field

Lower aquifer

Middle aquifer

Upper aquifer

Figure 2. Ground-water flow model grid used for contributing-area delineation, and outcrop 

areas of the Potomac-Raritan-Magothy aquifer system, Pennsauken Township and vicinity, 

Camden County, New Jersey.

Model Development and Calibration 5
The confining unit overlying the Middle aquifer is represented by a single model layer (C-1). The Middle aquifer is 

modeled as two sand units (A-2a and A-2b) and a thin intervening clay (A-2c1). In most areas, the heads in units A-2a 

and A-2b are similar.

The confining unit between the Middle and Lower 

aquifers is represented by three model layers—a low permeability layer (C-2a), a sandy unit (C-2AI) referred to in this 

report as the Intermediate sand, and an underlying layer that 

ranges from clay to sand (C-2b). Measured water levels in 

nested wells and data from well logs indicate that layer C-2b is 

more permeable than layer C-2a. In areas where the lower unit 

(C-2b) is more permeable, the Intermediate sand (C-2AI) is in 

direct connection with the underlying Lower aquifer. 

The Lower aquifer is represented by three sand units 

(A-3a, A-3b, and A-3c). The three layers allow the model 

to represent observed differences in conductivity, from least 

permeable in the uppermost part of the aquifer (near confining 

unit C-2b) to most permeable in the deepest part. The outcrop 

area of the Lower aquifer, as shown in figure 2, generally 

coincides with the Delaware River, and the aquifer is in direct 

contact with riverbed sediments. The lowest of these units, 

A-3c, represents a permeable gravel that is present throughout 

much of the model area. The base of the flow system is weathered bedrock or a clay unit overlying the bedrock (C3), which 

is considered to be impermeable.

The local flow model used for steady-state calibration 

consists of 85 rows, 108 columns, and 11 layers that represent 

both aquifers and confining units. Cell sizes used in the model 

range from 206 by 219 ft near the Puchack well field to 412 

by 440 ft at the edge of the model area. After calibration, the 

model was rediscretized to comply with NJDEP guidelines for 

delineating contributing areas. The model grid used for contributing-area delineation, along with the outcrop areas of the 

major aquifers, are shown in figure 2. The rediscretized local 

model has 104 rows and 121 columns but maintains the same 

11 layers vertically. Cell sizes range from 97 by 98 ft near the 

Puchack well field to 412 by 440 ft at the edge of the model.

Boundary Conditions

Model-boundary conditions are recharge due to precipitation, flow to and from the Delaware River and smaller 

tributary streams (surface water), and specified flow at lateral 

boundaries. In this section, the final model-calibration parameters for the boundary conditions are described and details of 

their application are provided.

Recharge

The simulated outcrop areas of the aquifer and confining units receive recharge by means of the MODFLOW-96 

Recharge package (Harbaugh and McDonald, 1996). Recharge 

is applied to the uppermost active cell at any location, except 

at river cells and where the Upper aquifer is confined; these 

areas do not receive recharge. Recharge zones and rates used 

in the model are shown in figure 3. Recharge zones were created using generalized land-use categories obtained from the 

New Jersey Integrated Terrain Unit (ITU) GIS digital data set 

for 1986 (New Jersey Department of Environmental Protection, 1996). The major land-use categories used to represent 

variations in ground-water recharge are open land, residential, 

landfill, commercial-industrial, and impervious. Recharge 

rates were assumed to be highest in open-land areas and lowest in impervious areas. The impervious category represents 

areas where land adjacent to the Delaware River has been 

filled and built up. On the basis of field visits, these areas are 

assumed to be relatively impermeable. 

Simulated recharge rates (shown on fig. 3) range from 

0 to 14 inches per year and are consistent with rates used in 

other models throughout the New Jersey Coastal Plain 

(Navoy and Carleton, 1995; Martin, 1998). 

Surface Water

The main surface-water body in the model area is the 

Delaware River and the largest tributary is Pennsauken Creek. 

Results of previous studies (Navoy and Carleton, 1995; 

Farlekas and others, 1976) and local aquifer tests (Ground 

Water Associates, Inc., 1995) indicate that the ground-water 

flow system in the study area is in hydraulic connection with 

the river and that the river contributes a large percentage of the 

inflow to the ground-water flow system. The Delaware River 

and its tributaries are tidal within the study area. Although 

river stage varies nearly 6 ft with each tidal cycle, it is the 

average state that is important for long-term ground-water 

model calibration (Navoy and Carleton, 1995). In order to 

simulate average annual conditions, the river stage in the 

model was assumed to be 0.5 ft above the NGVD of 1929 for 

all river cells. Riverbed sediments were assumed to be 10 ft 

thick in the main stem of the Delaware River and 3 ft thick in 

Pennsauken Creek. The zones of riverbed hydraulic conductivity, riverbed sediment thickness, and river stage used in 

this model are the same as those used by Navoy and Carleton 

(1995) in their model of the Camden area (fig. 4). The riverbed 

hydraulic conductivity zones from Navoy and Carleton (1995) 

were determined using surface-geophysical data collected 

by Duran (1986). Calibrated values of the riverbed hydraulic 

conductivity are shown in figure 4.

Flow in the Delaware River and Pennsauken Creek were 

simulated using the MODFLOW-96 River Package (Harbaugh 

and McDonald, 1996). The riverbed conductance (Criv) at 

each designated river cell (used as input to the River Package in the model) is calculated from the area of the river cell 

(area), the bed thickness (M), and the riverbed hydraulic conductivity (Kriv):

Criv = (Kriv * area) / M .

6 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 02’ 30" 40 00’ 75 00’

40

00’

39

57’

30"

75

05’

75

02’

30"

Pennsauken

Township

Merchantville

Borough

Camden City

Cherry

Hill

Township

Palmyra

Borough

Cinnaminson Township

Maple

Shade

Township

Delaware River

Pennsylvania

New Jersey

Camden County

Burlington County

EXPLANATION

Land use (used to determine recharge values).

Numbers in parentheses are ranges of recharge,

in inches per year. 

Puchack well field

Residential (7.5—10)

Landfill (6)

Open land (10.5—14)

Commercial-industrial (4.5—6)

Impervious (0)

Figure 3. Recharge used in the ground-water flow model, Pennsauken Township and vicinity, 

Camden County, New Jersey.

Model Development and Calibration 7
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

Pennsauken

Township

Merchantville

Borough

Camden City

Cherry

Hill

Township

Palmyra

Borough

Cinnaminson Township

Maple

Shade

Township

Delaware River

Pennsylvania

New Jersey

Camden County

Burlington County

EXPLANATION

ZONE OF VERTICAL HYDRAULIC CONDUCTIVITY--

Number in parentheses is hydraulic conductivity, in

feet per day

Low (0.00028)

Moderate (0.028)

High (28)

75 02’ 30" 40 00’ 75 00’

40

00’

39

57’

30"

75

05’

75

02’

30"

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 4. Hydraulic conductivity of the riverbed material, Pennsauken Township and vicinity, 

Camden County, New Jersey.

8 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Lateral Model Boundaries

The Potomac-Raritan-Magothy aquifer system is used 

heavily for ground-water supplies in the area. Explicit simulation of effects of these regional ground-water withdrawals 

would require a larger model area that includes hydrologic 

boundaries and withdrawal centers. This approach was impractical because of the level of detail needed in the local model 

area. Therefore, a regional-scale, model of the Potomac-Raritan-Magothy aquifer system in Camden County and parts of 

Burlington and Gloucester Counties (Navoy and Carleton, 

1995) was used to provide steady-state boundary fluxes to the 

local model. This approach allowed the regional effects that 

occur outside the model area to be included in the local model.

Boundary flows were assigned to local model layers 

representing the Upper aquifer (A-1), the Middle aquifer 

(A-2a and A-2b), and the Lower aquifer (A-3a, A-3b, and 

A-3c) using the Flow and Head Boundary (FHB) package 

(Leake and Lilly, 1997). Flows were not assigned to confining-unit layers because the regional model used a quasi-threedimensional approach in which the flow in the confining units 

was not simulated. Boundary flows from the Upper aquifer 

in the regional model were assigned to unit A-1. In the Upper 

aquifer, the fluxes along both the lateral and downgradient 

edges of the local model were important because flow volumes 

were large perpendicular to the local model boundaries near 

Pennsauken Creek to the north and the Cooper River to the 

south. Boundary flows from the Middle aquifer in the regional 

model were divided equally between local-model units A-2a 

and A-2b. Boundary flows from the Lower aquifer in the 

regional model were divided equally among local-model units 

A-3a, A-3b, and A-3c. 

Ground-Water Withdrawal Data

Monthly withdrawal data for public-supply wells in the 

local model area in 1998 were obtained from NJDEP Bureau 

of Water Allocation files. In some cases, however, only one 

value was reported for a well field because its wells were not 

metered individually at the time of data collection. To estimate 

withdrawals for individual wells, the reported withdrawal 

value for a well field was divided by the number of wells in 

that well field that were active at the time. Reported pump 

capacities at certain wells also were used to disaggregate the 

monthly data. 

In many cases, the screens of the public-supply wells 

cross more than one model layer. Therefore, the percentage 

of the well screen in each model layer was estimated and 

multiplied by the total withdrawal for the well to calculate the 

withdrawal for that model layer. This approach was considered 

to be reasonable because horizontal hydraulic conductivities 

were similar for model layers within the major (Middle and 

Lower) aquifers. 

The distribution of ground-water withdrawals from public-supply wells in the model area is shown in figure 5. Average withdrawals for January-March 1998 that were used in the 

model calibration are shown in figure 5 and table 3. 

Hydrogeologic Properties

Available hydraulic-conductivity data from aquifer 

tests, well acceptance tests, and results of previous simulations were used to assign initial values in the model. Hydraulic 

conductivities of aquifers and confining units were adjusted 

during model calibration in order to obtain a good fit to the 

observed flow system. The calibrated values of horizontal 

hydraulic conductivity for the aquifers and vertical hydraulic 

conductivity for the confining units are described in the 

following sections. 

Horizontal Hydraulic Conductivity of Aquifers and 

Confining Units

Calibrated values of horizontal hydraulic conductivity in the Potomac-Raritan-Magothy aquifer system used in 

the model ranged from 50 to 250 ft/d. The vertical hydraulic 

conductivity of the aquifer units was assumed to be one-tenth 

the horizontal hydraulic conductivity to account for bedding 

planes and laminations within the sediments (Anderson and 

Woessner, 1991).

The horizontal hydraulic conductivity of the Upper 

aquifer (A1) was simulated as a uniform value of 50 ft/d. 

The horizontal hydraulic conductivity of the Middle aquifer 

(A-2a and A-2b) used in the model was 60 ft/d. The Intermediate sand (C-2AI) was simulated using a hydraulic conductivity 

of 100 ft/d. The horizontal hydraulic conductivity of the confining layer within the Middle aquifer (A-2c1) is 4 ft/d. The 

horizontal hydraulic conductivity was assumed to be 

10 times the vertical hydraulic conductivity for all other 

confining-unit layers. 

All the layers in the Lower aquifer consist of permeable 

sands with relatively high hydraulic conductivity (130-

250 ft/d). The two upper layers (A3-a and A3-b) are composed 

of coarse sands. The lowermost layer in the Lower aquifer 

(A-3c) represents very coarse and highly conductive sands and 

gravels. The extent of layer A3-c and the zones of hydraulic 

conductivity within it (determined from well logs) are shown 

in figure 6. Horizontal hydraulic-conductivity values estimated 

from specific-capacity data from public-supply wells are 

shown in figure 6 and table 4. Estimates were made for wells 

with a specific-capacity test with a pumping rate of at least 

500 gal/min for a minimum of 8 hours. The transmissivity of 

the aquifer in the vicinity of these wells was estimated from 

specific-capacity data using the Theis equation (Heath, 1983). 

The horizontal hydraulic conductivity of layers A-3a, A-3b, 

and the portion of A-3c where the gravel unit is not present is 

130 ft/d. The conductivity of the permeable sand and gravel 

portions of A3-c is 250 ft/d. The conductivity values used 

in the model generally are lower than those estimated from 

specific-capacity data.

Model Development and Calibration 9
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 02’ 30" 40 00’ 75 00’

40

00’

39

57’

30"

75

05’

75

02’

30"

Pennsauken

Township

Merchantville

Borough

Camden City

Cherry

Hill

Township

Palmyra

Borough

Cinnaminson Township

Maple

Shade

Township

Delaware River

New Jersey

Pennsylvania

Camden County

Burlington County

Merchantville-Pennsauken

Water Company

National Highway well field

Merchantville-Pennsauken

Water Company

Marion well field 

Merchantville-Pennsauken

Water Company

Park Avenue well field

Merchantville-Pennsauken

Water Company

Woodbine well field

Merchantville-Pennsauken

Water Company

Browning well field

City of Camden

Puchack well field

City of Camden

Morris/Delair

well field

EXPLANATION

Puchack well field

GROUND-WATER WITHDRAWALS--From the Middle aquifer of the

Potomac-Raritan-Magothy aquifer system, January-March 1998,

in million gallons per month

GROUND-WATER WITHDRAWALS--From the Lower aquifer of the

Potomac-Raritan-Magothy aquifer system, January-March 1998,

in million gallons per month

Greater than 20 to 50

Greater than 75

Less than 20 Greater than 50 to 75

Greater than 50 to 75

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 5. Average ground-water withdrawals during January-March 1998 in the steady-state flow 

model, Pennsauken Township and vicinity, Camden County, New Jersey.

10 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Vertical Hydraulic Conductivity of Confining 

Units

Zones of vertical hydraulic conductivity representing 

similar confining-unit properties were created for each of the 

three major confining units (C-1, C-2a, and C-2b) by using 

geophysical logs. During model calibration, the boundaries 

of the zones and the vertical hydraulic-conductivity values 

were adjusted and refined.

The calibrated vertical hydraulic conductivity of the 

confining unit overlying the Middle aquifer (C1) ranged 

from 0.001 to 0.01 ft/d (fig. 7). The thin clay layer in the 

Middle aquifer (A2-c1) was assigned a uniform value of 

0.5 ft/d. The calibrated vertical hydraulic conductivity of the 

confining unit between the Middle aquifer and the Intermediate sand (C-2a) ranged from 0.01 to 0.06 ft/d (fig. 8). 

The calibrated vertical hydraulic conductivity of the 

confining unit between the Intermediate sand and the Lower 

aquifer (C2-b) ranged from 0.05 to 0.5 ft/d (fig. 9). In general, the vertical hydraulic conductivity of this confining unit 

was much higher than that of confining unit C1 or C-2a.

Model Calibration

The ground-water flow model was calibrated using a 

steady-state simulation of the ground-water flow system. 

Synoptic water-level data collected in March 1998 for 

individual aquifers, and vertical differences in water levels 

between aquifers at nested wells were used to calibrate the 

model. No streamflow data were available for use in calibration because the Delaware River and its tributaries are tidal 

in the model area. Flows were calibrated by using known 

ranges of recharge rates and boundary conditions from the 

regional model. 

Use of a steady-state simulation was considered to be 

reasonable because of several factors. In ground-water flow 

models of areas throughout the New Jersey Coastal Plain, 

the confined aquifers respond quickly to changes in stress. 

A hydrograph of Puchack well 3a shows that water levels 

recovered within 1 or 2 days when Puchack well 1 was shut 

down temporarily in March-April 1998 and quickly fell 

again when pumping at Puchack well 1 resumed (Walker, 

2001). Therefore, it is reasonable to assume that a steadystate simulation would approximate average monthly conditions.

Calibration Criteria

Prior to model calibration, criteria were established to 

evaluate the match between the simulation results and the 

measured data. Simulation results were evaluated by (1) 

comparing measured water levels at wells with simulated 

values (comparing residuals), (2) comparing water-level 

differences at nested observation wells with simulated waterlevel differences, and (3) ensuring that the flow budget and 

model input data were reasonable.

Table 3. Ground-water withdrawal data used in the ground-water 

flow model, Pennsauken Township and vicinity, Camden County, 

New Jersey.

[NJDEP, New Jersey Department of Environmental Protection; calibration 

withdrawals are average water use during January-March 1998; delineation 

withdrawals are 1998 withdrawals for all wells except Puchack wells; withdrawals for each Puchack well is 1 million gallons per day]

U.S. 

Geological 

Survey well 

number

NJDEP 

well 

permit 

number

Well name

Withdrawals, 

in million gallons

Calibration 

(3 months)

Delineation 

(1 year)

City of Camden

7-368 51-00053 DELAIR 1 86.80 288.1

7-369 51-00054 DELAIR 2 0 288.1

7-370 51-00055 DELAIR 3 86.80 288.1

7-390 51-00050 MORRIS 1 89.90 288.1

7-386 31-00945 MORRIS 3 89.90 288.1

7-382 31-04252 MORRIS 4 89.90 288.1

7-373 51-00051 MORRIS 6 19.40 79.0

7-375 31-00944 MORRIS 8 78.0 288.1

7-379 31-04251 MORRIS 10 89.90 288.1

7-545 31-15745 MORRIS 11 0 288.1

7-586 31-16814 MORRIS 12 89.90 288.1

7-587 31-16813 MORRIS 13 89.90 288.1

7-1070 31-56691 MORRIS 14 0 288.1

7-1071 31-57430 MORRIS 15 0 288.1

7-366 51-00056 PUCHACK 1 67.0 365.0

7-363 51-00057 PUCHACK 2 0 365.0

7-367 51-00058 PUCHACK 3 0 365.0

7-358 31-05450 PUCHACK 6 0 365.0

7-359 51-00059 PUCHACK 5 0 365.0

7-528 31-08526 PUCHACK 7 0 365.0

Merchantville-Pennsauken Water Company

7-319 31-05641 BROWNING 1 62.08 258.0

7-335 31-02915 MARION 1 2.65 126.8

7-332 31-04641 MARION 2 62.30 311.0

7-602 31-19207 NATIONAL HWY 2 69.40 260.0

7-349 31-00010 PARK AVE 1 41.76 156.2

7-350 51-00064 PARK AVE 2 41.76 156.2

7-348 31-03534 PARK AVE 3 41.76 156.2

7-345 31-00011 PARK AVE 5 41.76 156.2

7-530 31-14564 4R-A/PARK AVE 6 41.76 156.2

7-320 31-04642 WOODBINE 1 50.60 169.8

7-560 31-14563 WOODBINE 2 103.26 347.6

Model Development and Calibration 11
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 02’ 30" 40 00’ 75 00’

40

00’

39

57’

30"

75

05’

75

02’

30"

Pennsauken

Township

Merchantville

Borough

Camden City

Cherry

Hill

Township

Palmyra

Borough

Cinnaminson Township

Maple

Shade

Township

Delaware River

Pennsylvania

New Jersey

Camden County

193

253

479

148

520

217

142

320

656

1193

159 326

345

290

240

242

198

309

277

303

285

383

217

110

374

353

Burlington County

EXPLANATION

ZONE OF HORIZONTAL HYDRAULIC CONDUCTIVITY--

used in the model for layer A-3c. Number is hydraulic

conductivity, in feet per day. Conductivity values for zones

extend beneath the Delaware River.

250

130

LOCATION OF WELL--Shows where hydraulic

conductivity is estimated. Number is estimated

hydraulic conductivity, in feet per day 

520

Puchack well field

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 6. Horizontal hydraulic conductivity of the Lower aquifer of the Potomac-RaritanMagothy aquifer system in the ground-water flow model, Pennsauken Township and vicinity, 

Camden County, New Jersey.

12 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Table 4. Wells with aquifer-test data and estimates of hydraulic conductivity, Pennsauken Township and vicinity, Camden 

County, New Jersey.

[*, well has multiple screened intervals; --, data not available]

U.S. Geological 

Survey well 

number

Well name

Depth of well 

(feet below land 

surface)

Well diameter 

(inches)

Estimated 

hydraulic 

conductivity 

(feet per day)

Length of test 

(hours)

Discharge 

during test 

(gallons per 

minute)

7-109 CAMDEN DIV 46 178 12 520 8 1,400

7-111 CAMDEN DIV 50 170 12 479 8 1,000

7-325 BROWNING RD 2 240 -- 293 -- --

7-332 MARION 2 258 12 353 8 1,000

7-335 MARION 1 278 12 320 8 1,020

7-341 DELA GARDEN 2 145 12 217 8 728

7-342 DELA GARDEN 1A 139 12 142 8 882

7-344 PARK AVE REP 4 178 8 360 12 530

7-345 PARK AVE 5 288 12 383 8 1,010

7-346 PARK AVE 3A 260 11 110 24 720

7-347 PARK AVE 4 181 10 306 12 600

7-348 MPWC PARK AVE 3 275 12 303 8 1,030

7-349 PARK AVE 1 270 12 217 8 1,010

7-350 PARK AVE 2 257 12 303 8 1,000

7-369 DELAIR 2 146 26 656 * 8 1,330

7-370 DELAIR 3 132 26 1,193 * 8 1,850

7-373 MORRIS 6 138 26 345 8 1,700

7-374 MORRIS 9/9N 143 26 290 * 8 1,900

7-377 MORRIS 7 120 26 240 8 1,680

7-379 MORRIS 10 118 18 242 8 1,450

7-382 MORRIS 4A 134 18 198 8 1,590

7-386 MORRIS 3A 107 18 309 8 1,000

7-388 MORRIS 5 115 26 277 8 1,630

7-528 PUCHACK 7 180 18 159 8 1,290

7-530 4R-A/PARK AVE 6 270 36 285 8 1,520

7-545 MORRIS 11 149 16 326 24 2,030

7-547 54 200 16 193 24 1,210

7-597 55 176 -- 148 -- --

7-602 NATIONAL HWY 2 206 12 374 8 1,240

7-724 CLEVELAND AVE PW 53 194 16 253 24 1,210

Model Development and Calibration 13
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 02’ 30" 40 00’ 75 00’

40

00’

39

57’

30"

75

02’

30"

Merchantville

Borough

Camden City

Cherry

Hill

Township

Palmyra

Borough

Cinnaminson Township

Maple

Shade

Township

Delaware River

Pennsylvania

New Jersey

Camden County

Pennsauken

Township

EXPLANATION

ZONE OF VERTICAL HYDRAULIC CONDUCTIVITY--

Number is hydraulic conductivity, in feet per day.

Conductivity values for zones extend beneath the

Delaware River. 

Puchack well field

Burlington County

75

05’

0.0075

0.01

0.001

0.002

0.0035

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 7. Vertical hydraulic conductivity in confining unit C-1 (between the Upper and Middle 

aquifers of the Potomac-Raritan-Magothy aquifer system) in the ground-water flow model, 

Pennsauken Township and vicinity, Camden County, New Jersey. 

14 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 02’ 30" 40 00’ 75 00’

40

00’

39

57’

30"

75

05’

75

02’

30"

Camden City

Cherry

Hill

Township

Palmyra

Borough

Cinnaminson Township

Maple

Shade

Township

Delaware River

Pennsylvania

New Jersey

Camden County

Pennsauken

Township

Merchantville

Borough

EXPLANATION

Puchack well field

ZONE OF VERTICAL HYDRAULIC CONDUCTIVITY--

Number is hydraulic conductivity, in feet per day.

Conductivity values for zones extend beneath the

Delaware River. 

0.02

0.015

0.01

0.035

0.06

0.025

0.04

Burlington County

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 8. Vertical hydraulic conductivity in confining unit C-2a (between the Middle aquifer of 

the Potomac-Raritan-Magothy aquifer system and the Intermediate sand) in the ground-water 

flow model, Pennsauken Township and vicinity, Camden County, New Jersey.

Model Development and Calibration 15
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 02’ 30" 40 00’ 75 00’

40

00’

39

57’

30"

75

05’

75

02’

30"

Camden City

Cherry

Hill

Township

Palmyra

Borough

Cinnaminson Township

Maple

Shade Township

Delaware River

New Jersey

Pennsylvania

Camden County

Pennsauken

Township

Merchantville

Borough

Burlington County

EXPLANATION

ZONE OF VERTICAL HYDRAULIC CONDUCTIVITY--

Number is hydraulic conductivity, in feet per day.

Conductivity values for zones extend beneath the 

Delaware River.

Puchack well field

0.3

0.4

0.5

0.05

0.1

0.2

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 9. Vertical hydraulic conductivity in confining unit C-2b (between the Intermediate sand 

and the Lower aquifer of the Potomac-Raritan-Magothy aquifer system) in the ground-water 

flow model, Pennsauken Township and vicinity, Camden County, New Jersey.

16 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
NJDEP in accordance with delineation guidelines. For CWS 

wells, contributing areas were delineated by combining a Calculated Fixed Radius (CFR) analysis with a two-dimensional 

flow model. Post-processing programs rotate the contributing 

areas 20 degrees clockwise and counter-clockwise, using the 

well as a pivot point, to account for variability in the accuracy 

of the estimated hydraulic gradient. The NJDEP guidelines 

also allow the use of a three-dimensional flow model where 

hydrologic conditions are complex, such as in the vicinity of 

the Puchack well field in Pennsauken Township, New Jersey. 

The contributing area to this well field was delineated by using 

the local ground-water flow model. 

Delineation of contributing areas for the Puchack well 

field using a CFR analysis together with a two-dimensional 

flow model is difficult because 

(1) well-field interference from surrounding well fields

 (especially the Morris/Delair well field (fig. 1)) 

 affects the contributing area to the Puchack well field,

(2) the Puchack well field consists of multiple supply

 wells pumped in proximity to each other,

(3) the ground-water flow system is hydraulically 

 connected to the Delaware River. More than 90 per

 cent of the flow to wells adjacent to the river (Morris/

 Delair well field) is estimated to be derived from the 

 river. More than 80 percent of the flow to the Puchack 

 well field is estimated to be derived from the river, and

(4) although the Lower aquifer is confined in the area, 

 downward vertical flow is substantial because 

 withdrawals from the Lower aquifer are large. 

Contributing areas for the community water-supply wells 

in New Jersey were subdivided into three tiers corresponding 

to the ranges of travel time to the well specified by NJDEP: 

Tier 1 0 to 2 years

Tier 2 greater than 2 years to 5 years

Tier 3 greater than 5 years to 12 years

In order to determine the effects of variations in model 

parameters on the size and shape of the contributing area, 

each parameter was varied (as explained in the “Uncertainty 

Analysis” section) and a contributing area was determined for 

each simulation. The contributing area delineated using the 

calibrated model parameters is designated as the “delineation” 

contributing area. After contributing areas were delineated for 

each variation in model data, all of the data for the 37 contributing-area delineations were analyzed together. This process 

resulted in a map showing the number of simulations in which 

each model cell contributed water to the Puchack well field 

within the 12-year travel time to show the uncertainty in 

the contributing-area delineation. An aggregate contributing 

area that encompasses all areas that contributed flow to the 

Puchack well field within the 12-year time frame also was 

produced. Tiers were assigned by using the minimum travel 

time for each area.

Water levels measured in March 1998 were compared 

to average January-March simulated heads. The calibration 

criterion was that the simulated heads be within ± 5 ft of the 

measured heads. Water-level differences across confining units 

were used to help calibrate confining-unit vertical hydraulic 

conductivities. Where multiple wells were screened in different units (nested wells), the simulated and observed vertical 

differences in water levels were calculated. The calibration 

criterion was that the water-level differences be within ± 1 ft 

of each other. Well nests that were used to determine vertical 

hydraulic conductivity are shown in figure 10. 

Simulation of January-March 1998 Conditions

The model-calibration target was the set of water levels 

measured in March 1998. Average withdrawal data for January-March 1998 are shown in table 3 and figure 5. Only one 

well in the Puchack well field—Puchack 1—was pumping; the 

average withdrawal for that well during January-March 1998 

was 0.74 Mgal/d. 

The water levels in the Upper aquifer were not calibrated 

because few measurements of water levels in the unconfined 

parts of the Upper aquifer were available. The Upper aquifer 

was included in the model primarily to provide a pathway 

for vertical flow to reach the Middle aquifer and to serve as 

a boundary condition for the Middle aquifer. In much of the 

model area, the sands that make up the Upper aquifer are 

unsaturated as a result of pumping from the Lower aquifer. 

The simulated and observed potentiometric surfaces in 

the Middle and Lower aquifers for January-March 1998 are 

shown in figures 11 and 12, respectively. Near the Puchack 

well field, the simulated heads at the wells generally are within 

1 ft of the measured heads in both aquifers. In the Middle 

aquifer, residuals generally are larger and more variable in the 

area north of the well field than near it (fig. 11). In the Lower 

aquifer (fig. 12), residuals are larger in areas distant from 

the well field than near it. The few wells for which residuals 

exceed the 5-ft criterion are at or near withdrawal centers. In 

addition, measured water levels could be affected by as much 

as ± 5 to 10 ft at wells for which surveyed land-surface altitudes were not available and, therefore, where altitudes were 

estimated from contour maps. Differences between the simulated and observed gradient across confining units are shown 

in figure 13; the observed and simulated water-level measurements are listed in table 5. Most of the residuals were in the 

range of ± 0.5 ft, although a few were larger. The residual at 

MW-3 was larger than 1 ft, possibly because the measurements span both confining-unit layers C-2a and C-2b.

Contributing-Area Delineation

As discussed previously, contributing-area delineations 

are required for all public community water-supply (CWS) 

and non-community water-supply (NCWS) wells in New 

Jersey. Contributing areas for all wells were delineated by the 

Contributing-Area Delineation 17
MW-2

LFS

MW-1

MW-9

MW-3

MW-4

CCMW-2 MW-7

MW-10

CCMW-4

MW-6

MW-5 MW-8

LFN

CCMW-1

Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 02’ 30" 40 00’ 75 00’

40

00’

39

57’

30"

75

05’

75

02’

30" Pennsauken

Township

Merchantville

Borough

Camden City

Cherry

Hill

Township

Palmyra

Borough

Cinnaminson Township

Maple

Shade

Township

Delaware River

Pennsylvania

New Jersey

Camden County

Burlington County

EXPLANATION

NESTED OBSERVATION WELL- Identifier is

local name used by U.S. Geological Survey.

Puchack well field

0 375 750 1,500 METERS MW-2

0 0.25 0.5 1 MILE

Figure 10. Location of wells used to calibrate vertical hydraulic conductivity in the groundwater flow model, Pennsauken Township and vicinity, Camden County, New Jersey. 

18 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Figure 11. Simulated and measured potentiometric surfaces and residuals in the Middle aquifer of the 

Potomac-Raritan-Magothy aquifer system, Pennsauken Township and vicinity, Camden County, 

New Jersey, January-March 1998. 

Contributing-Area Delineation 19

-25

-25

-10

-10

- 5

-30

-25

-15

-15

- 20

-20

-10

-5

-5

-25

-5

-5

Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 02' 30" 40 00' 75 00'

40

00'

39

57'

30"

75

05'

75

02'

30"

Merchantville

Borough

Camden City

Cherry

Hill

Township

Palmyra

Borough

Cinnaminson Township

Maple

Shade

Township

Delaware River

Pennsylvania

New Jersey

Camden

County

Pennsauken

Township

EXPLANATION

MEASURED POTENTIOMETRIC CONTOUR--Shows

measured altitude at which water levels would have stood

in tightly cased wells. Contours are from Walker and Jacobsen

(2004) and are based on water levels measured in March 1998. 

Contour interval is 5 feet. Datum is NGVD of 1929

Puchack well field

1.85

-13.92

-2.01

-0.98

-0.41 -0.82

-1.35

0.17

-0.06

0.15

0.18

-1.10

-0.90 -0.75

-0.58

-0.23

-0.20

-1.10

-2.15

-1.39

-0.18 0.38

-2.09

3.73 -5.5

-7.62

-1.92

-18.20

Burlington County

LOCATION OF WELL--Shows the difference (residual) between

simulated and measured water levels (simulated - measured).

Number is difference in water level, in feet

0.17

SIMULATED POTENTIOMETRIC CONTOUR--Shows

simulated altitude at which water levels would have stood

in tightly cased wells. Contour interval is 5 feet. Datum is

NGVD of 1929

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE
Figure 12. Simulated and measured potentiometric surfaces and residuals in the Lower aquifer of the 

Potomac-Raritan-Magothy aquifer system, Pennsauken Township and vicinity, Camden County, New Jersey, 

January-March 1998.

20 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.

Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 02' 30" 40 00' 75 00'

40

00'

39

57'

30"

75

05'

75

02'

30"

Merchantville

Borough

Camden City

Cherry

Hill

Township

Palmyra

Borough

Cinnaminson Township

Maple

Shade

Township

Delaware River

Pennsylvania

New Jersey

Camden County

Burlington County

Pennsauken

Township

0

-5

-10

-15

-15

-20 -20

-25

-25

-20

-30

-30

-30

-30

-30

-35

-10

-20

-10

-30

-35

-40

-35

-40

-30

-20

-15

0.17

1.08

1.54

3.28

-12.04

1.51

3.05

-1.06

-17.53

-4.80

-0.4

-2.11

-4.87

-0.18

-0.61 -0.87

0.38 -0.31 2.90

3.07

-5.82

0.48

-9.05

-0.85

-1.26

-1.5

-1.51

-1.49

-1.19

-1.27 -0.96

-0.41

-0.47

-0.98

-0.84

-0.15 -0.78

-0.44

-0.03

-0.86

-0.22

2.913.12

1.54

-2.14

-1.89 -0.57

-20

-15

EXPLANATION

MEASURED POTENTIOMETRIC CONTOUR--Shows

measured altitude at which water levels would have stood

in tightly cased wells. Contours are from Walker and Jacobsen

(2004) and are based on water levels measured in March 1998. 

Contour interval is 5 feet. Datum is NGVD of 1929

Puchack well field

LOCATION OF WELL-Shows the difference

(residual) between simulated and measured water

levels (simulated - measured). Number is difference

in water level, in feet

SIMULATED POTENTIOMETRIC CONTOUR--

Shows the simulated altitude at which water levels

would have stood in tightly cased wells. Contour

interval is 5 feet. Datum is NGVD of 1929

-0.15

-20

-20

-20

-20

-20

-15

-15

-5

-5 0 375 750 1,500 METERS

0 0.25 0.5 1 MILE
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 02’ 30" 40 00’ 75 00’

40

00’

39

57’

30"

75

05’

75

02’

Pennsauken 30"

Township

Merchantville

Borough

Camden City

Cherry

Hill

Township

Palmyra

Borough

Cinnaminson Township

Maple

Shade

Township

Delaware River

New Jersey

Pennsylvania

Camden County

Burlington

County

-0.95

0.2

-0.44

-0.35

-1.13 -0.27

-0.24

0.52

-0.02

-0.03

-0.06 0.75

-0.45

0.49

0.14

0.74

0.12

-0.03

-0.06

EXPLANATION

LOCATION OF WELL-Shows difference between

simulated and measured water-level differences

across the confining units (simulated - measured).

Number in black is difference across confining

unit C-2a, in feet. Number in red is difference 

across confining unit C-2b, in feet

Puchack well field

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 13. Differences between simulated and measured gradients across confining units 

C-2a (between the Middle aquifer of the Potomac-Raritan-Magothy aquifer system and the 

Intermediate sand) and C-2b (between the Intermediate sand and the Lower aquifer of the 

Potomac-Raritan-Magothy aquifer system), Pennsauken Township and vicinity, Camden 

County, New Jersey, January-March 1998.

Contributing-Area Delineation 21
Table 5. Simulated and measured head differences at nested wells, Pennsauken Township and vicinity, Camden County, New Jersey.

[Well locations shown in figure 10; NGVD29, National Geodetic Vertical Datum of 1929]

Nest identifier

U.S. Geological 

Survey well 

number

Model layer 

(table 2)

Measured altitude 

of water level 

with respect to 

NGVD29 

(feet)

Measured 

water-level 

difference1

(feet)

Simulated 

altitude of water 

level with 

respect to 

NGVD29 

(feet)

Simulatedwater-level 

difference 

(feet)

Residual2 Confining unit

CCMW-1 7-852 5 -12.88 -1.12 -13.29 -1.39 -0.27 C-2a 7-851 7 -14.00 -14.68

CCMW-2 7-854 5 -14.51 -2.92 -14.36 -3.36 -.44 C-2a 7-853 7 -17.43 -17.72

CCMW-4 7-856 3 -12.89 -3.08 -13.79 -2.33 .75 3

C-2 7-855 10 -15.97 -16.12

MW-1 7-907 5 -9.34 -1.13

-.3

-11.35 -.61

-.32

.52

-.02

C-2a

C-2b 7-908 7 -10.47 -11.96

7-906 11 -10.77 -12.28

MW-2 7-909 7 -10.85 -.05 -12.11 -.29 -.24 C-2b 7-910 10 -10.90 -12.40

MW-3 7-911 5 -14.65 -1.74 -14.48 -2.87 -1.13 3

C-2 7-912 11 -16.39 -17.35

MW-4 7-913 5 -14.42 -2.96

.06

-14.48 -3.31

0

-.35

-.06

3

C-2

A-3a, A-3b 7-914 9 -17.38 -17.79

7-915 11 -17.32 -17.79

MW-5 7-916 3 -13.23 -2.59

0

-13.98 -2.62

-.06

-.03

-.06

A-2c1,C-2a

C-2b 7-917 7 -15.82 -16.60

7-918 10 -15.82 -16.66

MW-6 7-919 3 -13.20 -3.14 -14.30 -3.02 .12 A-2c1, C-2a

C-2b 7-920 11 -16.34 -17.32

MW-7 7-922 5 -13.43 -2.92 -14.01 -2.55 .14 3

C-2 7-921 10 -16.12 -16.56

MW-8 7-923 5 -11.26 -2.5 -12.61 -2.43 .49 3

C-2 7-924 11 -14.18 -15.04

MW-9 7-925 3 -15.66 .02

-1.92

-15.86 -.01

-1.72

-.03

.2

A-2c1

3

C-2 7-926 5 -15.64 -15.87

7-927 11 -17.56 -17.59

MW-10 7-928 5 -12.13 -.52 -12.95 -.97 -.45 3C-2

7-929 11 -12.65 -13.92

LFN 7-964 3 -8.43 -3.39 -10.35 -2.65 .74 A-2c1, C-2a 7-965 7 -11.82 -13.00

LFS 7-960 5 -16.57

-.06

-16.19

-1.01 -.95 3C-2 7-961 10 -16.63 -17.20

1

The water-level difference is the head at the well below the confining unit minus the head at the well above the confining unit. Negative differences indicate a downward gradient.

2

The residual is the simulated difference minus the measured difference.

3

C-2 denotes confining unit composed of both C-2a and C-2b. No wells are available to determine the vertical gradient in the Intermediate sand at these 

locations.

22 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Nine particles were placed at the surface of each model 

cell such that each particle would be at the center of a polygon 

that subdivides the model cell into three polygons along both 

the row and the column. This procedure effectively subdivides 

each cell into nine polygons for contributing-area delineation. 

The particles were then forward-tracked until they terminated, 

either by discharging to a well or by reaching a model boundary (flow boundary or the river). MODPATH particle starting locations and the cell at which the flow path terminated 

were converted to Geographic Information System (GIS) data 

using MODTOOLS (Orzol, 1997). Results were analyzed to 

identify starting locations of particles that terminated at any of 

the Puchack wells. Tier designations were assigned using the 

travel time computed by the particle-tracking program. This 

approach allowed the delineation of the contributing areas 

and tiers to be finer and smoother than that achieved by using 

the original model-grid cells. The same approach was used to 

delineate the contributing area to each individual well in the 

Puchack well field by grouping the data on the basis of the 

particular well to which the particle discharged.

Contributing Area

The contributing area for the Puchack well field determined by using the rediscretized model and the delineation 

water-use data set described in the previous section is shown 

in figure 14. The three tiers required for delineation of a Well 

Head Protection Area are shown, as well as the well-field 

contributing area from which the travel time was greater than 

12 years. The effect of withdrawals from nearby well fields on 

the contributing area to the Puchack well field is the capture of 

the areas updip from the Puchack well field by the Morris and 

Delair well fields (commonly referred to in combination as 

the Morris/Delair well field) operated by the City of Camden 

Water Department. A large percentage of the withdrawals from 

these well fields is derived from the Delaware River; consequently, the Puchack well field intercepts flow from the Delaware River only in a small strip between the Morris and Delair 

well fields (travel time less than 2 yrs) and from areas south 

of the Morris/Delair well field. The particle-tracking results 

indicate the necessity to use the three-dimensional flow model 

to delineate the contributing area accurately. If the effects of 

withdrawals from the Morris/Delair well field had not been 

considered, the resulting contributing area would have been 

smaller because the Puchack well field would have received 

more flow from the Delaware River. In contrast, if the contribution from the Delaware River had not been considered, the 

area contributing water to the Puchack well field would have 

been larger than the area shown in figure 14.

The individual contributing areas for the six wells in the 

Puchack well field are shown in figure 15. The contributing 

areas for Puchack 1 and Puchack 2 are much smaller than 

those for the other wells because these wells are nearest the 

river and therefore receive a larger percentage of their withdrawals from the river.

Simulation of Flow System

Where necessary, the existing flow model was modified 

to meet NJDEP guidelines for contributing-area delineations 

in complex settings (Spayd and Johnson, 2003). These modifications included rediscretizing the model grid in the horizontal direction and preparing the water-use data set for use 

in delineation as described below. In other cases, however, the 

calibrated model already met these NJDEP guidelines.

NJDEP guidelines state that the model cell containing 

the well whose contributing area is to be delineated may not 

exceed 100 ft in length or width and that the maximum cell 

size in the model must be less than 500 ft on a side. Modelcell sizes in the calibrated model range from 206 by 219 ft to 

412 by 440 ft. In the rediscretized model, the smallest cells 

were 97 by 98 ft and the largest cells, near the model boundaries, remained at 412 by 440 ft. The fine grid size is required in 

order to define the location of the supply well to within 100 ft. 

Reducing the size of the model cells containing wells allows 

the wells to be located more accurately but does not affect the 

calibration of the flow model.

NJDEP guidelines also state that the individual model 

layers may not exceed 100 ft in thickness. The 11 model layers used to account for vertical and horizontal variability in 

hydraulic parameters in the Puchack model met this criterion. 

Ground-water withdrawal data was prepared for input 

to the revised model. Because withdrawals from the Puchack 

well field were reduced greatly during the 1980’s and ultimately ceased in 1998 due to chromium contamination, the 

contributing area was delineated using a hypothetical data set. 

The major difference between the delineation withdrawals data 

set and the calibration withdrawals data set (January-March 

1998) is that the delineation data set is based on the assumption that the wells in the Puchack well field were pumping at 

full capacity, although this was not actually the case in 1998. 

Ground-water withdrawal data from surrounding well fields 

were specified using the average withdrawals for 1998 (listed 

as “delineation withdrawals” in table 3).

Particle Tracking

The particle-tracking computer program MODPATH 

(Pollack, 1994) was used with the rediscretized model to 

determine the areas on the land surface that contribute flow 

to the Puchack well field. MODPATH allows a hypothetical 

particle to be placed at any location within the model. The 

position of the particle is then calculated at successive intervals of simulated time as it moves through the flow field until 

it reaches a model boundary or discharge point. To calculate 

these positions, estimates of porosity are required. Porosity 

was estimated to be 20 percent for aquifer units and 25 percent 

for confining units. These values were estimated using typical 

values for sand and clay units and are similar to NJDEP’s recommended value of 25 percent (Spayd and Johnson, 2003).

Contributing-Area Delineation 23
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 06’ 75 04’ 75 02’

40

00’

39

58’

Pennsylvania

New Jersey

Delaware River

Burlington County

Camden County

Camden City Pennsauken Township

Palmyra Borough

EXPLANATION

TRAVEL TIME, IN YEARS

Puchack well field

Less than or equal to 2

Greater than 2 to 5

Greater than 5 to 12

Greater than 12

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 14. Simulated contributing area to the Puchack well field in the delineation simulation, Pennsauken Township 

and vicinity, Camden County, New Jersey.

24 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 06’ 75 04’ 75 02’

40

00’

39

58’

EXPLANATION

WELL LOCATION AND CONTRIBUTING

AREA TO WELL

Puchack well field

Puchack 6

Puchack 5

Puchack 2

Puchack 1

Puchack 3

Puchack 7

Pennsylvania

New Jersey

Delaware River

Burlington County

Camden County

Camden City Pennsauken Township

Palmyra Borough

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 15. Simulated contributing area to individual wells in the Puchack well field, Pennsauken Township and 

vicinity, Camden County, New Jersey.

Contributing-Area Delineation 25
Uncertainty Analysis

An uncertainty analysis was conducted to demonstrate 

the effects of changing model-input parameters on the simulated contributing area to the Puchack well field. The set of 

parameters used in a flow-model calibration is not unique. 

Different combinations of parameters could be used to obtain 

model results that meet the calibration criteria. Therefore, 

variations in model-input parameters can have a substantial 

effect on the size and shape of the contributing area without 

necessarily invalidating the model calibration. 

Approach

For this analysis, the model parameters were adjusted 

individually until the head change would result in a model that 

could no longer be considered “calibrated.” The parameters 

and the range over which they were varied are listed in table 

6. In most cases, the “appropriate range” (referred to in Spayd 

and Johnson, 2003) to be considered in the evaluation of 

model sensitivity to parameter values was determined by calculating the change (increase and decrease) in each parameter 

that would result in a maximum head change of ± 5 ft 

(the model-calibration criterion for heads) anywhere in the 

active model area. 

For five parameters related to recharge, withdrawals, 

and porosity, the 5-ft criterion was not applicable. For these 

parameters, values were changed as described below. Porosity 

could not be evaluated using the 5-ft criterion because porosity 

is not used in the flow model and does not affect the simulated 

heads; however, porosity is important in the determination of 

ground-water travel times. In the uncertainty analysis, porosity 

was varied by ± 5 percent. 

To evaluate the effects of variations in ground-water 

withdrawals, the well field that would have the largest effect 

on the contributing area of the Puchack well field (the Morris/

Delair well field) was selected. Wells in the Morris/Delair well 

field are along the Delaware River and Pennsauken Creek, a 

tributary. Simulation results show that wells in the southern 

part of the well field receive a larger percentage of flow from 

the Delaware River than do wells in the northern part of the 

well field. To bracket possible effects of pumping from the 

Morris/Delair well field, two distributions of withdrawals were 

simulated in which all of the withdrawals from the well field 

were attributed to wells in either the northern or the southern 

part of the well field. 

To evaluate the effect of applying a uniform recharge 

rate (rather than the spatially varied rate used in the calibrated 

model), a uniform recharge rate was calculated to provide the 

same recharge as in the calibrated model. The 5-ft threshold 

was applicable to this change. Once specified, however, the 

uniform recharge was both increased and decreased until the 

5-ft criterion was met.

Effects of Model-Input Parameter Values on 

Contributing Areas

Thirty-six simulations were made in which individual 

parameter values were varied. The 5-ft head-change criterion 

was used to evaluate the ranges of values for horizontal and 

vertical hydraulic conductivity, riverbed hydraulic conductivity, and some recharge parameters. The final model parameter 

estimates and the percentage increases and decreases to each 

parameter required to cause a ± 5-ft maximum head change 

for these runs are shown in table 6. The magnitude of the 

percent increases and decreases can be used as an indicator of 

model sensitivity to that parameter. Variations in parameters to 

which the 5-ft head-change criterion was not applied also are 

shown in table 6.

Contributing areas were delineated for each of the model 

runs shown in table 6. The resulting contributing areas were 

compared visually with the contributing area to the Puchack 

well field from the delineation simulation (fig. 14). Contributing areas from several selected model runs are shown in 

figures 16 through 25. In general, these model runs were 

selected as examples because of large differences in the shape, 

size, or tier distribution of the contributing area from that of 

the basic delineation.

Porosity

Porosity had the greatest effect on the size and shape of 

the contributing area associated with each of the travel-time 

tiers. Changes to porosity changed the time required for individual particles to reach the well field. Decreasing the porosity to 15 percent in aquifers and 20 percent in confining units 

(fig. 17) expanded the size of the contributing areas associated 

with the 2-to-5-year and 5-to-12-year travel times, because the 

particle velocity increases as porosity decreases.

Withdrawals

The distribution of withdrawals from the Morris/Delair 

well field also affected the size and shape of the contributing 

area to the Puchack well field. When all of the withdrawals 

were applied to the wells in the northern part of the well field 

(fig. 18), the contributing area was similar to that in the delineation simulation except that the area in the Delaware River 

immediately updip from the well field with a travel time of 2 

to 5 years was larger (wider). Also, compared to the delineation simulation, a greater percentage of the withdrawals from 

the Puchack well field was derived from the Delaware River. 

When all of the withdrawals were applied to the southern part 

of the Morris/Delair well field (fig. 19), the area of the 2-to5-year travel-time zone updip from the well field was smaller 

and the overall contributing area was larger (especially north 

of the well field). In this case, a smaller percentage of the 

withdrawals from the Puchack well field was derived from the 

river and a greater percentage was derived from areas north of 

the Puchack well field.

26 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Table 6. Model runs and parameter changes in the ground-water flow model, Pennsauken Township and vicinity, Camden County, New Jersey.

[--, not applicable; *,variation not based on head change criterion; model layers shown in table 2]

Model-layer 

designation Initial value

Increased value to produce a 

maximum 5-foot change in head 

at any model cell

Decreased value to 

produce a maximum 5-foot 

change in head at any model cell

Figure 

number Comments

Changed value Percent change Changed value Percent change

Horizontal hydraulic conductivity, in feet per day

A-1 50 77 54 37 26 --A-2a, A-2b 60 90 50 43 28 22, 23C-2AI 100 178 78 35 65 --A-3a, A-3b 130 153 18 110 15 --A-3c 130, 250 160, 308 23 105, 202 19 24, 25 Distribution of calibrated values shown in figure 6.

Vertical hydraulic conductivity, in feet per day

C-1 0.001–0.01 0–0.0138 38 0–0.008 20 -- Distribution of calibrated values shown in figure 7.A2-c1 4 36 800 .28 93 --C-2a .01–0.06 .13–0.84 1,300 0.0039–0.0234 61 -- Distribution of calibrated values shown in figure 8.C-2b .05–0.5 .13–1.3 167 0.0235–0.235 53 -- Distribution of calibrated values shown in figure 9.A-1 5 6.3 26 4 20 --A-2a, A-2b 6 120 1,900 1.3 78 26, 27C-2AI 10 200 1,900 1.8 82 --A-3a 13 260 1,900 1 92 --A-3b 13 300 2,200 1.3 90 --

Riverbed vertical hydraulic conductivity, in feet per day

-- .00028–28 .00034–33.9 21 .00023–23 18 -- Distribution of calibrated values shown in figure 4.

Recharge, in inches per year

All 4.5–14 5.8–18.1 29 3.1–.5 32 20, 21 The model-calibrated variable recharge was varied. Distribution of calibrated values shown in figure 3.All 7.88 * * * * -- An average uniform value for recharge was used throughout 

the model area.

All 7.88 0, 10.3 31 0, 5.4 35 -- The average uniform recharge value was varied until a 5-foot 

change in head was reached.

Riverbed vertical hydraulic conductivity, in feet per day

-- .00028–28 .00034–33.9 21 .00023–23 18 -- Distribution of calibrated values shown in figure 4.

Withdrawals

A-3a, A-3b, A-3c -- -- * -- * 18 Withdrawals in the Morris/Delair well field were moved to 

the northern part of the well field.

A-3a, A-3b, A-3c -- -- * -- * 19 Withdrawals in the Morris/Delair well field were moved to 

the southern part of the well field.

Porosity

Aquifers .2 -- * -- * 16, 17 Porosity in the aquifers was increased to 0.25 and decreased 

to 0.15. 

Confining units .25 Porosity in the confining units was increased to 0.3 and 

decreased to 0.2.

Contributing-Area Delineation 27
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 06’ 75 04’ 75 02’

40

00’

39

58’

Pennsylvania

New Jersey

Delaware River

Burlington County

Camden County

Camden City Pennsauken Township

Palmyra Borough

EXPLANATION

Puchack well field

TRAVEL TIME, IN YEARS

Less than or equal to 2

Greater than 2 to 5

Greater than 5 to 12

Greater than 12 

Contributing area in

delineation simulation 

(fig. 14, travel time less 

than 12 years) 0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 16. Simulated contributing area to Puchack well field when porosity is increased to 25 percent in aquifers 

and 30 percent in confining units, Pennsauken Township and vicinity, Camden County, New Jersey.

28 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 06’ 75 04’ 75 02’

40

00’

39

58’

Pennsylvania

New Jersey

Delaware River

Burlington County

Camden County

Camden City Pennsauken Township

Palmyra Borough

EXPLANATION

TRAVEL TIME, IN YEARS

Less than or equal to 2

Greater than 2 to 5

Greater than 5 to 12

Greater than 12 

Contributing area in

delineation simulation

(fig. 14, travel time

less than 12 years)

Puchack well field

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 17. Simulated contributing area to Puchack well field when porosity is decreased to 15 percent in aquifers 

and 20 percent in confining units, Pennsauken Township and vicinity, Camden County, New Jersey.

Contributing-Area Delineation 29
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 06’ 75 04’ 75 02’

40

00’

39

58’

Pennsylvania

New Jersey

Delaware River

Burlington County

Camden County

Camden City Pennsauken Township

Palmyra Borough

EXPLANATION

TRAVEL TIME, IN YEARS

Less than or equal to 2

Greater than 2 to 5

Greater than 5 to 12

Greater than 12 

Contributing area in

delineation simulation

(fig. 14, travel time

less than 12 years)

Puchack well field

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 18. Simulated contributing area to Puchack well field when withdrawals at the Morris/Delair well field are 

distributed in the northern part of the well field, Pennsauken Township and vicinity, Camden County, New Jersey. 

30 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 06’ 75 04’ 75 02’

40

00’

39

58’

Pennsylvania

New Jersey

Delaware River

Burlington County

Camden County

Camden City Pennsauken Township

Palmyra Borough

EXPLANATION

TRAVEL TIME, IN YEARS

Puchack well field

Contributing area in

delineation simulation

(fig. 14, travel time

less than 12 years)

Less than or equal to 2

Greater than 2 to 5

Greater than 5 to 12

Greater than 12 

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 19. Simulated contributing area to Puchack well field when withdrawals at the Morris/Delair well field are 

distributed in the southern part of the well field, Pennsauken Township and vicinity, Camden County, New Jersey. 

Contributing-Area Delineation 31
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 06’ 75 04’ 75 02’

40

00’

39

58’

Pennsylvania

New Jersey

Delaware River

Burlington County

Camden County

Camden City Pennsauken Township

Palmyra Borough

EXPLANATION

TRAVEL TIME, IN YEARS

Puchack well field

Contributing area in

delineation simulation

(fig. 14, travel time

less than 12 years)

Less than or equal to 2

Greater than 2 to 5

Greater than 5 to 12

Greater than 12 

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 20. Simulated contributing area to Puchack well field when recharge is increased 29 percent, Pennsauken 

Township and vicinity, Camden County, New Jersey.

32 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 06’ 75 04’ 75 02’

40

00’

39

58’

Pennsylvania

New Jersey

Delaware River

Burlington County

Camden County

Camden City Pennsauken Township

Palmyra Borough

EXPLANATION

TRAVEL TIME, IN YEARS

Puchack well field

Contributing area in

delineation simulation

(fig. 14, travel time

less than 12 years)

Less than or equal to 2

Greater than 2 to 5

Greater than 5 to 12

Greater than 12 

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 21. Simulated contributing area to Puchack well field when recharge is decreased 32 percent, Pennsauken 

Township, Camden County, New Jersey.

Contributing-Area Delineation 33
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 06’ 75 04’ 75 02’

40

00’

39

58’

Pennsylvania

New Jersey

Delaware River

Burlington County

Camden County

Camden City Pennsauken Township

Palmyra Borough

EXPLANATION

TRAVEL TIME, IN YEARS

Puchack well field

Contributing area in

delineation simulation

(fig. 14, travel time

less than 12 years)

Less than or equal to 2

Greater than 2 to 5

Greater than 5 to 12

Greater than 12 

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 22. Simulated contributing area to Puchack well field when the hydraulic conductivity of the Middle aquifer 

of the Potomac-Raritan-Magothy aquifer system is increased 50 percent, Pennsauken Township and vicinity, Camden 

County, New Jersey.

34 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 06’ 75 04’ 75 02’

40

00’

39

58’

Pennsylvania

New Jersey

Delaware River

Burlington County

Camden County

Camden City Pennsauken Township

Palmyra Borough

EXPLANATION

TRAVEL TIME, IN YEARS

Puchack well field

Contributing area in

delineation simulation

(fig. 14, travel time

less than 12 years)

Less than or equal to 2

Greater than 2 to 5

Greater than 5 to 12

Greater than 12 

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 23. Simulated contributing area to Puchack well field when the hydraulic conductivity of the Middle aquifer 

of the Potomac-Raritan-Magothy aquifer system is decreased 28 percent, Pennsauken Township and vicinity, 

Camden County, New Jersey.

Contributing-Area Delineation 35
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 06’ 75 04’ 75 02’

40

00’

39

58’

Pennsylvania

New Jersey

Delaware River

Burlington County

Camden County

Camden City Pennsauken Township

Palmyra Borough

EXPLANATION

TRAVEL TIME, IN YEARS

Puchack well field

Contributing area in

delineation simulation

(fig. 14, travel time

less than 12 years)

Less than or equal to 2

Greater than 2 to 5

Greater than 5 to 12

Greater than 12 

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 24. Simulated contributing area to Puchack well field when the hydraulic conductivity of the Lower aquifer of 

the Potomac-Raritan-Magothy aquifer system (model layer A-3c) is increased 23 percent, Pennsauken Township and 

vicinity, Camden County, New Jersey. 

36 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 06’ 75 04’ 75 02’

40

00’

39

58’

Pennsylvania

New Jersey

Delaware River

Burlington County

Camden County

Camden City Pennsauken Township

Palmyra Borough

EXPLANATION

TRAVEL TIME, IN YEARS

Puchack well field

Contributing area in

delineation simulation

(fig. 14, travel time

less than 12 years)

Less than or equal to 2

Greater than 2 to 5

Greater than 5 to 12

Greater than 12 

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 25. Simulated contributing area to Puchack well field when the hydraulic conductivity of the Lower aquifer of 

the Potomac-Raritan-Magothy aquifer system (model layer A-3c) is decreased 19 percent, Pennsauken Township and 

vicinity, Camden County, New Jersey.

Contributing-Area Delineation 37
vertical flow in the vicinity of the well field supplies about 

20 percent of flow to the Puchack well field (as estimated from 

particle-tracking results).

As the vertical hydraulic conductivities of the upper units 

(A1, C1, A-2a, and A-2b) increase, more water comes from 

the recharge applied at the land surface and the sizes of the 

contributing areas away from the Delaware River increase 

(fig. 26). The area of the 12-year travel-time tier is smaller in 

the simulation when the vertical hydraulic conductivity of the 

Middle aquifer units is decreased (fig. 27) than in any of the 

other 36 simulations. In general, the model was sensitive to 

changes in the vertical hydraulic conductivity of the uppermost units in the model (A1, C1, C-2a, and C-2b).

Aggregate Contributing Area

The results of the uncertainty analysis described above 

were used to determine the aggregate contributing area to the 

Puchack well field. Particle starting locations, termination 

sites, and travel times from the particle-tracking analysis for 

the delineation simulation (1 run) and for each of the model 

runs in which model-input data were varied (36 runs) were 

combined. The combined data were grouped by particle 

starting location. The number of times (out of 37) each area 

contributed flow to the Puchack well field with travel times 

less than 12 years was determined (fig. 28). Variations in the 

contributing area to the Puchack well field due to changes in 

model-parameter values were relatively small. Taken together, 

the areas that contributed flow to the Puchack well field in at 

least 31 of the simulations most closely match the size and 

shape of the contributing area in the delineation simulation.

The aggregate contributing area that accounts for the 

uncertainty in the model is shown in figure 29. The travel 

times shown are the shortest travel times that occurred for 

each area. The shape of the aggregate contributing area is most 

similar to that resulting from the run in which porosity was 

decreased (fig. 17), because changes in porosity had a substantial effect on travel time.

Recharge

Increasing recharge decreased the size of the area 

contributing water from the Delaware River for both the 

2-to-5-year and 5-to-12-year travel-time zones (fig. 20). 

Conversely, decreasing recharge increased the contribution 

from the river and decreased the area of the 5-to-12-year 

travel-time zone (fig. 21). 

Hydraulic Conductivity

Changes in the hydraulic conductivity of the Middle aquifer (units A-2a and A-2b) and of unit A-3c in the Lower aquifer (figs. 22-25) caused changes in the sizes of the travel-time 

tiers of the contributing areas as well as in the percent changes 

required to cause a 5-ft change in simulated water levels for 

the variables (table 6). Changes in the horizontal hydraulic 

conductivity of the Lower aquifer affect the contributing area 

to the Puchack well field by controlling flow between the 

Lower aquifer and the Delaware River.

Hydraulic conductivity affects the contributing areas 

because, as shown by particle-tracking analysis using the flow 

model, about 80 percent of the water supplying the Puchack 

well field comes from the Delaware River, and the hydraulic 

conductivity of the Lower aquifer is high and the hydraulic 

connection between the Lower aquifer and the riverbed sediments is good. Therefore, the model was sensitive to changes 

in the hydraulic conductivity of the Lower aquifer.

Vertical Hydraulic Conductivity

The vertical hydraulic conductivity of the Upper and 

Middle aquifers (A1, A-2a, and A-2b) and the vertical hydraulic conductivity of the confining unit overlying the Middle 

aquifer (C1) affect the contributing area to the Puchack well 

field by controlling flow between the Lower aquifer and areas 

where recharge is applied (away from the river). The vertical 

hydraulic conductivities of these units are important because 

they control vertical flow in the vicinity of the well field; 

38 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 06’ 75 04’ 75 02’

40

00’

39

58’

EXPLANATION

TRAVEL TIME, IN YEARS

Puchack well field

Contributing area in

delineation simulation

(fig. 14, travel time

less than 12 years)

Less than or equal to 2

Greater than 2 to 5

Greater than 5 to 12

Greater than 12 

Pennsylvania

New Jersey

Delaware River

Burlington County

Camden County

Camden City Pennsauken Township

Palmyra Borough

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 26. Simulated contributing area to Puchack well field when the vertical hydraulic conductivity of the Middle 

aquifer of the Potomac-Raritan-Magothy aquifer system is increased 1,900 percent, Pennsauken Township and vicinity, Camden County, New Jersey.

Contributing-Area Delineation 39
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 06’ 75 04’ 75 02’

40

00’

39

58’

EXPLANATION

TRAVEL TIME, IN YEARS

Puchack well field

Contributing area in

delineation simulation

(fig. 14, travel time

less than 12 years)

Less than or equal to 2

Greater than 2 to 5

Greater than 5 to 12

Greater than 12 

Pennsylvania

New Jersey

Delaware River

Burlington County

Camden County

Camden City Pennsauken Township

Palmyra Borough

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 27. Simulated contributing area to Puchack well field when the vertical hydraulic conductivity of the Middle 

aquifer of the Potomac-Raritan-Magothy aquifer system is decreased 78 percent, Pennsauken Township and vicinity, 

Camden County, New Jersey.

40 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 06’ 75 04’ 75 02’

40

00’

39

58’

Pennsylvania

New Jersey

Delaware River

Burlington County

Camden County

Camden City Pennsauken Township

Palmyra Borough

Number of model runs in which

area contributed flow (travel time

less than 12 years)

EXPLANATION

Puchack well field

Contributing area in

delineation simulation

(fig. 14, travel time

less than 12 years)

1

2 - 6

7 - 20

21 - 30

31 - 36

37

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 28. Number of model runs in which each area contributed flow to the Puchack well field in the uncertainty 

analysis, Pennsauken Township and vicinity, Camden County, New Jersey.

Contributing-Area Delineation 41
Base from U.S. Geological Survey digital data 1:24,000

Universal Transverse Mercator Projection, Zone 18, NAD83

75 06’ 75 04’ 75 02’

40

00’

39

58’

Pennsylvania

New Jersey

Delaware River

Burlington County

Camden County

Camden City Pennsauken Township

Palmyra Borough

EXPLANATION

TRAVEL TIME, IN YEARS

Puchack well field

Less than or equal to 2

Greater than 2 to 5

Greater than 5 to 12

0 375 750 1,500 METERS

0 0.25 0.5 1 MILE

Figure 29. Simulated aggregate contributing area to the Puchack well field including the effects of uncertainty 

analysis, Pennsauken Township and vicinity, Camden County, New Jersey.

42 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Summary

The Well Head Protection Program in New Jersey 

requires delineation of Well Head Protection Areas (WHPA’s). 

The NJDEP delineated WHPA’s for all public community 

water-supply wells in New Jersey using standard methods. 

State guidelines also allow the use of a three-dimensional 

ground-water flow model where hydrologic conditions are 

complex. 

A local ground-water flow model was developed that 

used a detailed 11-layer representation of the hydrogeologic 

units is used to account for local variations in hydrogeology. 

The local model was nested within a regional model to obtain 

boundary flows that used a more general 5-layer representation of the hydrogeology. The most important differences 

between the local 11-layer framework and the regional 5-layer 

framework included modifications to the representation of the 

confining unit between the Middle and Lower aquifers and differences in the variability of hydraulic properties in the Lower 

aquifer. The confining unit between the Middle and Lower 

aquifers is represented by three units in the local model—a 

relatively low-permeability layer (C-2a); a sandy unit (C-2AI) 

referred to as the Intermediate sand in this report; and an 

underlying layer that varies from clay to sand (C-2b). In many 

areas the lowermost of these units (C-2b) is relatively permeable and the Intermediate sand (C-2AI) is in direct connection 

with the Lower aquifer. The Lower aquifer is represented by 

three sand units in the local model—A-3a, A-3b, and A-3c. 

The lowermost of these units, A-3c, represents a very permeable gravel that is present throughout much of the model area. 

Model-boundary conditions include recharge from precipitation, flow from the Delaware River and smaller tributary 

streams, and specified-flow boundaries. The simulated outcrop 

areas of the aquifers and confining units receive recharge at 

rates ranging from 0 to 14 inches per year, determined on the 

basis of zones representing the predominant land use. The 

Delaware River, the main surface-water body in the area, 

contributes a large volume of water to the ground-water-flow 

system and supplies much of the water withdrawn from the 

local public-supply wells. Streambed sediments underlying the 

Delaware River were characterized as having high, moderate, 

or low permeability. Calibrated riverbed hydraulic-conductivity values ranged from 0.00028 ft/d to 28 ft/d. The model was 

nested within a larger regional model of the Potomac-RaritanMagothy aquifer system that was used to provide boundary 

conditions for the local model. Flows were input from the 

regional model along the lateral model boundaries and where 

the Upper aquifer is confined.

Horizontal hydraulic conductivities used in the calibrated 

model ranged from 50 ft/d for the Upper aquifer to 250 ft/d 

for the most productive (lowermost) unit in the Lower aquifer. Zones of vertical hydraulic conductivity were determined 

using geophysical logs. Vertical hydraulic conductivities in the 

confining units ranged from 0.001 to 0.5 ft/d and were highest 

in unit C-2b overlying the Lower aquifer. 

The local ground-water flow model was calibrated using 

a steady-state simulation of average withdrawals during 

January-March 1998. The model-calibration target was water 

levels measured in March 1998. Near the Puchack well field, 

the simulated heads at the wells generally were within 1 ft of 

the measured heads in both the Middle and Lower aquifers. 

In the Lower aquifer, residuals were larger in areas distant 

from the Puchack well field. Differences between simulated 

and observed gradients across confining units generally were 

within ± 0.5 ft. 

The model used in calibration was modified to meet 

NJDEP guidelines for delineating contributing areas in complex hydrogeologic settings. These modifications included 

rediscretizing the model grid and preparing the water-use data 

set for use in delineation. Contributing areas to the Puchack 

well field were delineated using particle tracking. Estimates 

of porosity of 20 percent for aquifer units and 25 percent for 

confining units were used for particle-tracking analysis.

The contributing area for the Puchack well field is 

affected by withdrawals from nearby well fields. The City of 

Camden Water Department Morris/Delair well field is located 

between the Puchack well field and the Delaware River. A 

large percentage of the flow to the Morris/Delair wells is 

derived from the Delaware River. Consequently, the Puchack 

well field receives flow from the Delaware River only from a 

small strip between the Morris and Delair well fields and from 

areas south of the Morris/Delair well field. 

An uncertainty analysis was conducted to demonstrate 

the effects of changes in the model-input values on the 

contributing area to the Puchack well field. For this analysis, 

the values of the model parameters were varied individually. 

Where possible, the values of 36 variables were adjusted until 

simulated heads changed ± 5 ft from the calibrated-model 

heads (using the 5-ft model-calibration criterion for heads). 

Input data that were adjusted but to which the 5-ft change 

criterion was not applicable were related to withdrawals, 

uniform recharge, and porosity.

Porosity has the greatest effect on the size and shape of 

the contributing areas for each travel-time tier. Decreasing the 

porosity to 15 percent in aquifers and 20 percent in confining 

units expanded the size of the contributing area. Likewise, an 

increase in recharge decreased the area contributing flow from 

the Delaware River, whereas a decrease in recharge increased 

the contribution from the river. 

The results of the 36 uncertainty-analysis simulations and 

the delineation contributing area were combined to determine 

the aggregate contributing area to the Puchack well field. 

Variations in the contributing area to the Puchack well field 

resulting from changes in model parameters are relatively 

small. An aggregate contributing area, defined as any zone that 

contributed flow to the Puchack well field within the specified 12-year travel time, was delineated. The “tiers” of this 

contributing area (0-2, >2-5, and >5-12 years) were assigned 

by the model run that produced the shortest travel time to the 

Puchack well field. Because decreasing porosity had the largSummary 43
Martin, Mary, 1998, Ground-water flow in the New Jersey 

Coastal Plain: U.S. Geological Survey Professional Paper 

1404-H, 146 p.

Navoy, A.S., and Carleton, G.B., 1995, Ground-water flow and 

future conditions in the Potomac-Raritan-Magothy aquifer 

system, Camden area, New Jersey: New Jersey Geological 

Survey Report GSR 38, 184 p.

New Jersey Department of Environmental Protection, 1996, 

New Jersey geographic information system: Trenton, N.J., 

New Jersey Department of Environmental Protection, 

CD-ROM series 1, v. 2.

Orzol, L.L., 1997, User's guide for MODTOOLS: Computer 

programs for translating data of MODFLOW and 

MODPATH into geographic information system files: 

U.S. Geological Survey Open-File Report 97-240, 86 p. 

Owens, J.P., and Minard, J.P., 1979, Upper Cenozoic sediments of the Lower Delaware Valley and the northern 

Delmarva Peninsula, New Jersey, Pennsylvania, Delaware, 

and Maryland: U.S. Geological Survey Professional Paper 

1067-D, 47 p.

Pollock, D.W., 1994, User’s guide for MODPATH/MODPATH-PLOT, version 3: A particle-tracking post-processing package for MODFLOW, the U.S. Geological Survey 

finite-difference ground-water flow model: U.S. Geological 

Survey Open-File Report 94-464, 6 chap.

Spayd, S.E., and Johnson, S.W., 2003, Guidelines for delineation of well head protection areas in New Jersey: Trenton, 

N.J., New Jersey Department of Environmental Protection, 

New Jersey Geological Survey, 30 p.

Walker, R.L., 2001, Effects of pumping on ground-water flow 

near water-supply wells in the Lower Potomac-Raritan aquifer, Pennsauken Township, Camden County, New Jersey: 

U.S. Geological Survey Water-Resources Investigations 

Report 00-4012, 12 p.

Walker, R.L., and Jacobsen, E.J., 2004, Reconnaissance of 

hydrogeology and ground-water quality, Pennsauken Township and vicinity, Camden County, New Jersey, 1996-98: 

U.S. Geological Survey Water-Resources Investigations 

Report 03-4247, 102 p.

Zapecza, O.S., 1989, Hydrogeologic framework of the New 

Jersey Coastal Plain: U.S. Geological Survey Professional 

Paper 1404-B, 49 p., 24 pl.

est effect on the tiers in the contributing areas, the final aggregate contributing area was most similar to that resulting from 

the uncertainty run in which the porosity in both the aquifers 

and confining units was decreased.

Acknowledgments

The authors thank Robert Gallagher and Akshay Pariakh 

of the NJDEP for information about contamination at the 

Puchack well field. Robert Nicholson of the USGS and Steven 

Spayd of the New Jersey Geological Survey provided technical input on contributing-area delineations. Alison Gordon of 

the USGS assisted with the uncertainty analysis.

Literature Cited

Anderson, M.P., and Woessner, W.W., 1991, Applied groundwater modeling: Simulation of flow and advective transport: 

San Diego, Academic Press, 381 p.

Duran, P.B., 1986, Distribution of bottom sediments and 

effects of proposed dredging in the ship channel of the 

Delaware River between Northeast Philadelphia, Pennsylvania, and Wilmington, Delaware, 1984: U.S. Geological 

Survey Hydrologic Atlas 697, 1 sheet, scale 1:48,000.

Farlekas, G.M., Nemickas, Bronius, and Gill, H.E., 1976, 

Geology and ground-water resources of Camden County, 

New Jersey: U.S. Geological Survey Water-Resources 

Investigations Report 76-76, 146 p.

Ground Water Associates, Inc., 1995, 30-Day aquifer test for 

evaluation of induced groundwater recharge, Delaware 

Garden well No. 1: Bridgewater, N.J., Ground Water Associates, Inc., unpaginated.

Harbaugh, A.W., and McDonald, M.G., 1996, User’s documentation for MODFLOW-96, an update to the U.S. Geological Survey modular finite-difference ground-water flow 

model: U.S. Geological Survey Open-File Report 96-485, 

56 p.

Heath, R.C., 1983. Basic ground-water hydrology: U.S. Geological Survey Water-Supply Paper 2220, 84 p.

Leake, S.A., and Lilly, M.R., 1997, Documentation of a computer program (FHB1) for assignment of transient specified-flow and specified-head boundaries in applications 

of the modular finite-difference ground-water flow model 

(MODFLOW): U.S. Geological Survey Open-File Report 

97-571, 50 p.

44 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Table 1. Well-construction data for wells used in the ground-water flow model, Pennsauken Township and vicinity, Camden 

County, New Jersey.—Continued.

[NJDEP, New Jersey Department of Environmental Protection; NGVD29, National Geodetic Vertical Datum of 1929; --, data not available]

U.S. Geological 

Survey well 

number

Well name NJDEP well 

permit number

Aquifer 

code1

Altitude of land 

surface2

(feet above 

NGVD29) 

Depth of well 

(feet below 

land surface)

Screened interval 

(feet below land surface)

Top Bottom

5-1418 PSLF MW-12 31-26580 MRPAM 18.2 33 13 33

7-94 CITY 16 31-01249 MRPAL 23 179 149 179

7-109 CAMDEN DIV 46 31-00162 MRPAL 11 178 148 178

7-111 CAMDEN DIV 50 31-03456 MRPAL 9 170 139 170

7-319 1R/BROWNING 1A 31-05641 MRPAM 15 152 132 152

7-320 WOODBINE 1 31-04642 MRPAL 69 285 245 285

7-325 BROWNING RD 2 31-03987 MRPAL 25 240 207 237

7-332 MARION 2 31-04641 MRPAL 72 258 223 258

7-335 MARION 1 31-02915 MRPAL 61 278 243 278

7-341 DELA GARDEN 2 31-01417 MRPAL 45.3 145 115 145

7-342 DELA GARDEN 1A 31-05228 MRPAL 28 139 109 139

7-344 PARK AVE REP 4 -- MRPAL -- 178 153 178

7-345 PARK AVE 5 31-00011 MRPAL 17 288 248 288

7-346 PARK AVE 3A -- MRPAL 30 260 210 260

7-347 PARK AVE 4 -- MRPAL 20 181 146 181

7-348 MPWC PARK AVE 3 31-03534 MRPAL 25 275 240 275

7-349 PARK AVE 1 31-00010 MRPAL 8 270 240 270

7-350 PARK AVE 2 51-00064 MRPAL 12 257 232 257

7-358 PUCHACK 6 31-05450 MRPAL 47.5 220 170 220

7-359 PUCHACK 5 51-00059 MRPAL 27.8 208 181 204

7-363 PUCHACK 2 51-00057 MRPAL 13.8 170 124 164

7-366 PUCHACK 1 51-00056 MRPAL 12.2 140 107 137

7-367 PUCHACK 3 51-00058 MRPAL 13.6 176 139 176

7-368 DELAIR 1 51-00053 MRPAL 10 138 106 126

7-369 DELAIR 2 51-00054 MRPAL 5 146 111 141

7-370 DELAIR 3 51-00055 MRPAL 6 132 107 127

7-372 NATIONAL HWY 1 31-05110 MRPAL 68 231 195 230

7-373 MORRIS 6 51-00051 MRPAL 5.9 138 98 133

7-374 MORRIS 9/9N 51-00076 MRPAL 6.8 143 99 118

7-375 MORRIS 8 31-00944 MRPAL 6 128 89 124

7-377 MORRIS 7 51-00052 MRPAL 6 120 85 120

7-379 MORRIS 10 31-04251 MRPAL 8.7 118 75 115

7-382 MORRIS 4A 31-04252 MRPAL 6 134 95 130

7-386 MORRIS 3A 31-00945 MRPAL 10 107 73 103

7-387 MORRIS 2 51-51106 MRPAL 6 123 93 123

7-388 MORRIS 5 -- MRPAL 5 115 80 115

7-390 MORRIS 1 51-00050 MRPAL 6 107 93 118

7-528 PUCHACK 7 31-08526 MRPAL 20.1 180 140 180

7-530 4R-A/PARK AVE 6 31-14564 MRPAL 40 270 240 270

7-536 TW-3-79 31-15369 MRPAL 10 117 85 115

Table 1 45
Table 1. Well-construction data for wells used in the ground-water flow model, Pennsauken Township and vicinity, Camden 

County, New Jersey.—Continued.

[NJDEP, New Jersey Department of Environmental Protection; NGVD29, National Geodetic Vertical Datum of 1929; --, data not available]

U.S. Geological 

Survey well 

number

Well name NJDEP well 

permit number

Aquifer 

code1

Altitude of land 

surface2

(feet above 

NGVD29) 

Depth of well 

(feet below 

land surface)

Screened interval 

(feet below land surface)

Top Bottom

7-537 TW-4-79 -- MRPAL 10 128.33 97 128.33

7-538 TW-5-79 -- MRPAL 10 129 80 110

7-540 TW-7-79 31-14569 MRPAL 10 141 98 138

7-545 MORRIS 11 31-15745 MRPAL 15.3 149 102 144

7-547 54 31-18944 MRPAL 35 200 155 195

7-560 WOODBINE 2 31-14563 MRPAL 58 226 196 226

7-568 LANDFILL 1 -- MRPAM 24.9 60 59 60

7-571 LANDFILL 4 -- MRPAM 24.6 48 47 48

7-586 MORRIS 12 31-16814 MRPAL 10 122 86 117

7-587 MORRIS 13 31-16813 MRPAL 10 135 90 130

7-597 55 31-20270 MRPAL 11 176 136 176

7-602 NATIONAL HWY 2 31-19207 MRPAL 35 206 182 206

7-724 CLEVELAND AVE PW 53 31-18947 MRPAL 32 194 154 194

7-848 BISHOP EUSTACE PREP 31-17884 MRPAM 25 150 135 150

7-851 CAMDEN CITY MW-1A 31-37328 MRPAL 73.6 140.94 130.94 140.94

7-852 CAMDEN CITY MW-1B 31-37329 MRPAM 73.7 103.8 93.8 103.8

7-853 CAMDEN CITY MW-2A 31-37326 MRPAL 57.4 174 164 174

7-854 CAMDEN CITY MW-2B 31-37327 MRPAM 57.2 120 110 120

7-855 CAMDEN CITY MW-4A 31-37359 MRPAL 54.9 202 192 202

7-856 CAMDEN CITY MW-4B 31-37360 MRPAM 54.7 86 76 86

7-906 PUCHACK MW-1D 31-51230 MRPAL 38.9 177 162 172

7-907 PUCHACK MW-1S 31-51229 MRPAM 39.0 61 51 56

7-908 PUCHACK MW-1M 31-51228 MRPAL 39.0 100 85 95

7-909 PUCHACK MW-2M 31-51226 MRPAL 31.6 103 88 98

7-910 PUCHACK MW-2D 31-51227 MRPAL 30.8 155 140 150

7-911 PUCHACK MW-3M 31-51222 MRPAM 78.4 138 128 133

7-912 PUCHACK MW-3D 31-51223 MRPAL 78.8 287 272 282

7-913 PUCHACK MW-4M 31-51224 MRPAM 60.6 123 108 118

7-914 PUCHACK MW-4I 31-52598 MRPAL 60.2 201 186 196

7-915 PUCHACK MW-4D 31-51225 MRPAL 60.6 260 245 255

7-916 PUCHACK MW-5M 31-51695 MRPAM 35.8 78 63 73

7-917 PUCHACK MW-5I 31-52597 MRPAL 35.5 135 120 130

7-918 PUCHACK MW-5D 31-51696 MRPAL 35.6 190 175 185

7-919 PUCHACK MW-6M 31-51697 MRPAM 26.4 74 59 69

7-920 PUCHACK MW-6D 31-51698 MRPAL 26.4 193 178 188

7-921 PUCHACK MW-7D 31-51699 MRPAL 58.2 202 187 197

7-922 PUCHACK MW-7M 31-51700 MRPAM 58.0 110.5 95.5 105.5

7-923 PUCHACK MW-8M 31-51702 MRPAM 23.7 55 40 50

7-924 PUCHACK MW-8D 31-51701 MRPAL 23.7 165 150 160

7-925 PUCHACK MW-9S 31-51705 MRPAM 22.2 49 36 46

46 Use of a Ground-Water Flow Model to Delineate Contributing Areas to the Puchack Well Field, Camden County, N.J.
Table 1. Well-construction data for wells used in the ground-water flow model, Pennsauken Township and vicinity, Camden 

County, New Jersey.—Continued.

[NJDEP, New Jersey Department of Environmental Protection; NGVD29, National Geodetic Vertical Datum of 1929; --, data not available]

U.S. Geological 

Survey well 

number

Well name NJDEP well 

permit number

Aquifer 

code1

Altitude of land 

surface2

(feet above 

NGVD29) 

Depth of well 

(feet below 

land surface)

Screened interval 

(feet below land surface)

Top Bottom

7-926 PUCHACK MW-9M 31-51704 MRPAM 22.5 70 55 65

7-927 PUCHACK MW-9D 31-51703 MRPAL 23.3 181 166 176

7-928 PUCHACK MW-10M 31-51900 MRPAM 43.6 91 76 86

7-929 PUCHACK MW-10D 31-51901 MRPAL 43.6 202 187 197

7-930 PUCHACK MW-12M 31-51906 MRPAL 33.7 170 155 165

7-931 PUCHACK MW-14 31-52706 MRPAL 56.3 133 118 128

7-932 DELA GARDEN R-1 31-43420 MRPAL 28.7 145 125 145

7-933 HOLMAN ENT P-47-D 31-45075 MRPAL 28.4 182 177 182

7-934 HOLMAN ENT P-45-D 31-45076 MRPAM 28.5 120 100 120

7-940 SUPER TIRE MW-2D 31-35902 MRPAM 36.6 75 55 75

7-943 KING ARTHUR MW-5S 31-36280 MRPAM 64.7 91 71 91

7-944 KING ARTHUR MW-5D 31-36279 MRPAL 64.7 140 125 140

7-948 GSM MW-11 31-33572-1 MRPAM 34.0 63 53 63

7-954 PSLF MW-7 -- MRPAM 71.4 115.08 95.17 115.08

7-957 PSLF MW-3D 31-26142-6 MRPAL 60.6 177 157 177

7-958 PSLF MW-5 31-18183 MRPAM 72.3 109.75 89.75 109.75

7-959 PSLF MW-5D 31-26143-4 MRPAL 72 187 167 187

7-960 PSLF MW-6 31-19602 MRPAM 37.4 80.42 60.33 80.42

7-961 PSLF MW-6D 31-26141-8 MRPAL 38.4 149 129 149

7-962 PSLF MW-2 31-17781 MRPAM 70.0 100 90 100

7-963 PSLF MW-13 31-29056-6 MRPAM 17.1 44.24 29.24 44.24

7-964 PSLF MW-11 31-24601-1 MRPAM 19.0 30 10 30

7-965 PSLF MW-11D 31-26140-0 MRPAL 18.7 105 85 105

7-1070 MORRIS 14 31-56691 MRPAL 11 125 93 120

7-1071 MORRIS 15 31-57430 MRPAL 12 128 93 123

1

Aquifer code: MRPAM, Middle Potomac-Raritan-Magothy aquifer; MRPAL, Lower Potomac-Raritan-Magothy aquifer.

2

Values of altitude of land surface listed as whole numbers were determined by visual inspection of a 1:24,000-scale topographic map or by altimeter. 

Values listed to the tenths place were determined by level measurement.

Table 1 47
For additional information, write to:

U.S. Geological Survey

Water Resources Division

New Jersey District

Mountain View Office Park

810 Bear Tavern Rd., Suite 206

West Trenton, NJ 08628

or visit our Web site at:

http://nj.water.usgs.gov

To request numerical model input data sets in 

electronic form, contact the information officer, 

U.S. Geological Survey, New Jersey District, or 

call (609) 771-3900.