GROUND-WATER FLOW IN THE 

NEW JERSEY COASTAL PLAIN

ZUSGS

science tor a changing world

PROFESSIONAL PAPER 1404-H
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Ground-Water Flow in the New Jersey 

Coastal Plain

By Mary Martin

REGIONAL AQUIFER-SYSTEM ANALYSIS 

NORTHERN ATLANTIC COASTAL PLAIN

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1404-H

1998
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

Charles G. Groat, Director

Any use of trade, product, or firm names in this publication is for

descriptive purposes only and does not imply endorsement by the

U.S. Government

Library of Congress Cataloging in Publication Data

Martin, M.M.

Ground-water flow in the New Jersey coastal plain / by Mary Martin.

p. cm. (U.S. Geological Survey professional paper ; 1404-H (Regional aquifer-system analysis northern Atlantic

coastal plain)

Includes bibliographical references. 

Supt.ofDocs.no.: I 19.16:1404-H 

1. Groundwater flow New Jersey. 2. Aquifers New Jersey. I. Title. II. Series. III. Series: Regional aquifer-system

analysis northern Atlantic coastal plain. 

QE75.P9 no. 1404-H

[GB1197.7] 557.3 s-dc 20 [551.49'09749] 91^1172

CIP

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

Box 25286, Federal Center, Denver, CO 80225
FOREWORD

THE REGIONAL AQUIFER-SYSTEM ANALYSIS PROGRAM

The RASA Program represents a systematic effort to study a number of 

the Nation's most important aquifer systems, which, in aggregate, underlie 

much of the country and which represent an important component of the 

Nation's total water supply. In general, the boundaries of these studies are 

identified by the hydrologic extent of each system and, accordingly, transcend the political subdivisions to which investigations have often arbitrarily been limited in the past. The broad objective for each study is to 

assemble geologic, hydrologic, and geochemical information, to analyze and 

develop an understanding of the system, and to develop predictive capabilities that will contribute to the effective management of the system. The use 

of computer simulation is an important element of the RASA studies to 

develop an understanding of the natural, undisturbed hydrologic system 

and the changes brought about in it by human activities and to provide a 

means of predicting the regional effects of future pumping or other stresses. 

The final interpretive results of the RASA Program are presented in a 

series of U.S. Geological Survey Professional Papers that describe the 

geology, hydrology, and geochemistry of each regional aquifer system. Each 

study within the RASA Program is assigned a single Professional Paper 

number beginning with Professional Paper 1400.

Charles G. Groat 

Director

CONTENTS

Foreword......................................................................... Ill

Abstract........................................................................... HI

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

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

Location and Extent....................................................... 2

Previous Investigations ................................................... 2

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

Conceptual Hydrogeologic Model.......................................... 4

Aquifer and Confining-Unit Characteristics......................... 6

Lower Potomac-Raritan-Magothy Aquifer.................... 7

Confining Unit Between the Lower and Middle

Potomac-Raritan-Magothy Aquifers.................... 29

Middle Potomac-Raritan-Magothy Aquifer ................. 29

Confining Unit Between the Middle and Upper

Potomac-Raritan-Magothy Aquifers.................... 30

Upper Potomac-Raritan-Magothy Aquifer.................. 30

Merchantville-Woodbury Confining Unit.................... 30

Englishtown Aquifer.............................................. 31

Marshalltown-Wenonah Confining Unit ..................... 31

Wenonah-Mount Laurel Aquifer............................... 31

Navesink-Hornerstown Confining Unit...................... 32

Vincentown Aquifer............................................... 32

Vincentown-Manasquan Confining Unit..................... 32

Piney Point Aquifer ............................................... 32

Basal Kirkwood Confining Unit................................ 33

Lower Kirkwood-Cohansey Aquifer and Confined

Kirkwood Aquifer............................................ 33

Confining Unit Overlying the Rio Grande WaterBearingZone.................................................. 34

Upper Kirkwood-Cohansey Aquifer .......................... 34

Estuarine Clay Confining Unit................................. 34

Holly Beach Aquifer............................................... 34

Conceptual Hydrogeologic Model Continued

Ground-Water Flow System.........................................

Simulation of Ground-Water Flow .......................................

Digital Model.............................................................

Approach ............................................................

Grid Design.........................................................

Boundary Conditions.............................................

Model Input Data.................................................

Model Calibration.......................................................

Approach ............................................................

Simulation of Prepumping Steady-State Conditions ....

Simulation of Transient Conditions ..........................

Evaluation of Hydraulic Characteristics and Flow System 

Based on Simulation...........................................

Transmissivity .....................................................

Vertical Leakance of Confining Units.......................

Aquifer Storage....................................................

Prepumping Steady-State Flow System....................

1978 Transient-State Flow System ..........................

Sensitivity Analysis ....................................................

Transmissivity and Vertical Leakance of the

Confining Units..............................................

Aquifer Storage....................................................

Downdip Boundaries.............................................

Boundary Flows...................................................

Confining-Unit Storage..........................................

Additional Evaluation of Flow and Boundary Conditions...

Transient-Flow Conditions .....................................

Flow Near the Downdip Boundary ..........................

Source of Water to Wells .......................................

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

References Cited..............................................................

H35 

37 

37 

37

39

40

43

48

48

50

64

78

78

90

100

100

108

116

119

121

121

121

122

124

124

125

126

132

134

ILLUSTRATIONS

FIGURE 1. Map showing location of study area .................................................................................................................... H3

2. Sketch showing generalized hydrogeologic section of the New Jersey Coastal Plain.................................................... 6

3-22. Maps showing 

3. Altitude of the top of the lower Potomac-Raritan-Magothy aquifer................................................................. 8

4. Thickness of the confining unit between the lower and middle Potomac-Raritan-Magothy aquifers....................... 9

5. Altitude of the top of the middle Potomac-Raritan-Magothy aquifer ............................................................... 10

6. Thickness of the confining unit between the middle and upper Potomac-Raritan-Magothy aquifers ...................... 11

7. Altitude of the top of the upper Potomac-Raritan-Magothy aquifer................................................................. 12

8. Thickness of the Merchantville-Woodbury confining unit............................................................................... 13

9. Altitude of the top of the Englishtown aquifer............................................................................................ 14

10. Thickness of the Marshalltown-Wenonah confining unit................................................................................ 15
VI CONTENTS

FIGURES 3-22. Continued 

11. Altitude of the top of the Wenonah-Mount Laurel aquifer ........................................................................... H16

12. Thickness of the Navesink-Hornerstown confining unit............................................................................... 17

13. Altitude of the top of the Vincentown aquifer............................................................................................ 18

14. Thickness of the Vincentown-Manasquan confining unit.............................................................................. 19

15. Altitude of the top of the Piney Point aquifer............................................................................................ 20

16. Thickness of the basal Kirkwood confining unit.......................................................................................... 21

17. Altitude of the top of the lower Kirkwood-Cohansey aquifer and confined Kirkwood aquifer............................. 22

18. Thickness of the confining unit overlying the Rio Grande water-bearing zone................................................. 23

19. Altitude of the top of the confined part of the upper Kirkwood-Cohansey aquifer............................................ 24

20. Thickness of the estuarine clay confining unit............................................................................................ 25

21. Generalized patterns of prepumping ground-water flow in four Coastal Plain aquifers...................................... 36

22. Major cones of depression in three Coastal Plain aquifers, 1978.................................................................... 38

23. Schematic representation of aquifers, confining units, and boundary conditions in the digital flow model...................... 39

24. Flow chart of modeling approach showing relation of New Jersey subregional flow model to the northern Atlantic

Coastal Plain regional and Maryland-Delaware subregional flow models ............................................................ 40

25. Map showing finite-difference grid, flow-budget areas, and generalized lateral model boundaries................................. 41

26. Schematic representation of stream-aquifer flow, deep percolation, and the upper boundary in the 10-layer and

11-layer models........................................................................................................................................ 43

27, 28. Maps showing generalized altitude of 

27. The water table, prepumping conditions................................................................................................... 45

28. Streams.............................................................................................................................................. 46

29. Graph showing total annual ground-water withdrawals and average withdrawals for each pumping period for the

New Jersey Coastal Plain.......................................................................................................................... 48

30-51. Maps showing 

30. Simulated prepumping potentiometric surface of the lower Potomac-Raritan-Magothy aquifer........................... 51

31. Simulated prepumping potentiometric surface of the middle Potomac-Raritan-Magothy aquifer......................... 52

32. Simulated and interpreted prepumping potentiometric surfaces for the upper Potomac-Raritan-Magothy

aquifer.......................................................................................................................................... 53

33. Simulated and interpreted prepumping potentiometric surfaces for the Englishtown aquifer............................. 54

34. Simulated and interpreted prepumping potentiometric surfaces for the Wenonah-Mount Laurel aquifer.............. 55

35. Simulated and interpreted prepumping potentiometric surfaces for the Vincentown aquifer.............................. 56

36. Simulated and interpreted prepumping potentiometric surfaces for the Piney Point aquifer.............................. 57

37. Simulated and interpreted prepumping potentiometric surfaces and measured prepumping water levels

for the lower Kirkwood-Cohansey aquifer and confined Kirkwood aquifer................................................ 58

38. Simulated and interpreted prepumping water tables and potentiometric surfaces for the upper KirkwoodCohansey aquifer............................................................................................................................ 59

39. Simulated and interpreted prepumping water tables for the Holly Beach aquifer ............................................ 60

40. Simulated prepumping ground-water flow from and to the unconfined outcrop areas in the 10-layer model.......... 62

41. Simulated prepumping ground-water flow to streams in the 11-layer model.................................................... 63

42. Simulated and interpreted 1978 potentiometric surfaces for the lower Potomac-Raritan-Magothy aquifer............ 65

43. Simulated and interpreted 1978 potentiometric surfaces for the middle Potomac-Raritan-Magothy aquifer .......... 66

44. Simulated and interpreted 1978 potentiometric surfaces for the upper Potomac-Raritan-Magothy aquifer............ 67

45. Simulated and interpreted 1978 potentiometric surfaces for the Englishtown aquifer....................................... 68

46. Simulated and interpreted 1978 potentiometric surfaces for the Wenonah-Mount Laurel aquifer........................ 69

47. Simulated 1978 potentiometric surface for the Vincentown aquifer................................................................ 70

48. Simulated 1978 potentiometric surface and measured 1978 water levels for the Piney Point aquifer ................... 71

49. Simulated and interpreted 1978 potentiometric surfaces and measured 1978 water levels for the lower

Kirkwood-Cohansey aquifer and confined Kirkwood aquifer................................................................... 72

50. Simulated 1978 water table, simulated and interpreted 1978 potentiometric surfaces, and measured 1978

water levels for the upper Kirkwood-Cohansey aquifer......................................................................... 73

51. Simulated 1978 water table and measured 1978 water levels for the Holly Beach aquifer.................................. 74

52-54. Hydrographs of simulated and measured water levels for the 

52. Potomac-Raritan-Magothy aquifers.......................................................................................................... 75

53. Englishtown and Wenonah-Mount Laurel aquifers ..................................................................................... 76

54. Confined Kirkwood and upper Kirkwood-Cohansey aquifer.......................................................................... 77

55-64. Maps showing transmissivity used in the model for the 

55. Lower Potomac-Raritan-Magothy aquifer................................................................................................. 79

56. Middle Potomac-Raritan-Magothy aquifer................................................................................................. 80

57. Upper Potomac-Raritan-Magothy aquifer ................................................................................................. 81

58. Englishtown aquifer.............................................................................................................................. 82

59. Wenonah-Mount Laurel aquifer............................................................................................................... 83

60. Vincentown aquifer............................................................................................................................... 84

61. Piney Point aquifer............................................................................................................................... 85
CONTENTS VII

FIGURES 55-64. Continued 

62. Lower Kirkwood-Cohansey aquifer and confined Kirkwood aquifer............................................................. H86

63. Upper Kirkwood-Cohansey aquifer ....................................................................................................... 87

64. Holly Beach aquifer............................................................................................................................ 88

65-73. Maps showing vertical leakance used in the model for the 

65. Confining unit between the lower and middle Potomac-Raritan-Magothy aquifers......................................... 91

66. Confining unit between the middle and upper Potomac-Raritan-Magothy aquifers......................................... 92

67. Merchantville-Woodbury confining unit.................................................................................................. 93

68. Marshalltown-Wenonah confining unit................................................................................................... 94

69. Navesink-Hornerstown confining unit.................................................................................................... 95

70. Vincentown-Manasquan confining unit................................................................................................... 96

71. Basal Kirkwood confining unit.............................................................................................................. 97

72. Confining unit overlying the Rio Grande water-bearing zone..................................................................... 98

73. Estuarine clay confining unit................................................................................................................ 99

74. Diagrams showing simulated prepumping flow in two hydrogeologic sections of the Coastal Plain............................. 101

75-80. Maps showing simulated prepumping flow through the top of the 

75. Lower Potomac-Raritan-Magothy aquifer............................................................................................... 103

76. Middle Potomac-Raritan-Magothy aquifer .............................................................................................. 104

77. Upper Potomac-Raritan-Magothy aquifer............................................................................................... 105

78. Englishtown aquifer ........................................................................................................................... 106

79. Wenonah-Mount Laurel aquifer............................................................................................................ 107

80. Lower Kirkwood-Cohansey aquifer and confined Kirkwood aquifer............................................................. 109

81. Diagrams showing simulated flow in two hydrogeologic sections of the Coastal Plain, 1978 ...................................... 110

82-87. Maps showing simulated January 1, 1978, flow through the top of the 

82. Lower Potomac-Raritan-Magothy aquifer............................................................................................... Ill

83. Middle Potomac-Raritan-Magothy aquifer .............................................................................................. 113

84. Upper Potomac-Raritan-Magothy aquifer............................................................................................... 114

85. Englishtown aquifer ........................................................................................................................... 115

86. Wenonah-Mount Laurel aquifer............................................................................................................ 117

87. Lower Kirkwood-Cohansey aquifer and confined Kirkwood aquifer............................................................. 118

88-91. Graphs of simulated prepumping and January 1, 1978, flow rates and source of water to wells for the 

88. Potomac-Raritan-Magothy aquifers, central Camden County area.............................................................. 127

89. Middle Potomac-Raritan-Magothy aquifer, Middlesex and Monmouth Counties............................................. 128

90. Englishtown and Wenonah-Mount Laurel aquifers, Ocean and Monmouth Counties....................................... 129

91. Confined Kirkwood aquifer, Atlantic County .......................................................................................... 130

TABLES

	Page

TABLE 1. Previous hydrogeologic investigations ...................................................................................................................... H4

2. Geologic and hydrogeologic units of the New Jersey Coastal Plain and model units used in this study ................................ 5

3. Summary of data on transmissivity, hydraulic conductivity, and storage coefficient for aquifers in the New Jersey

	Coastal Plain.................................................................................................................................................. 26

4. Summary of vertical hydraulic-conductivity data for confining units in the New Jersey Coastal Plain ................................. 28

5. Summary of hydraulic-conductivity values based on specific-capacity tests and initial estimates of transmissivity ................. 44

6. Summary of hydrologic budget analyses used to estimate ground-water recharge............................................................ 47

7. Ground-water withdrawals and lateral boundary flows for each pumping period.............................................................. 48

8. Range of transmissivity and confining-unit vertical leakance used in the calibrated model................................................. 89

9. Results of sensitivity analyses on transmissivity and confining-unit leakance .................................................................. 120

10. Boundary flows for prepumping conditions and for January 1, 1978, for each aquifer ....................................................... 122

11. Results of boundary-flow sensitivity analysis............................................................................................................. 123

12. Simulated source of water to wells for each pumping period ........................................................................................ 131

13. Simulated rate of water released from aquifer storage for each aquifer.......................................................................... 131

14. Simulated flow to and from constant-head nodes for each pumping period...................................................................... 132

15. Comparison between simulated and measured water levels at the end of each pumping period .......................................... 137
VIII CONTENTS

CONVERSION FACTORS AND VERTICAL DATUM

Multiply English unit

cubic foot per second (ft3/s) 

foot (ft)

foot per day (ft/d)

foot squared per day (ft2/d)

foot per day per foot ((ft/d)/ft)

gallon per minute (gal/min)

inch (in.)

inch per year (in/yr)

million gallons (Mgal)

million gallons per day (Mgal/d)

mile (mi)

square mile (mi2 )

by to obtain metric unit

0.02832 cubic meter per second

0.3048 meter

0.3048 meter per day

0.0929 meter squared per day

1.00 meter per day per meter

0.06309 liter per second

2.54 centimeter

2.54 centimeter per year

3785 cubic meter

3785 cubic meter per day

1.609 kilometer

2.590 square kilometer

The National Geodetic Vertical Datum of 1929 (NGVD of 1929) is a geodetic datum derived from a 

general adjustment of the first-order level nets of both the United States and Canada, formerly called 

"Sea Level Datum of 1929."
REGIONAL AQUIFER-SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

GROUND-WATER FLOW IN THE NEW JERSEY COASTAL PLAIN

By MARY MARTIN

ABSTRACT

Ground-water flow was simulated in 10 aquifers and 9 intervening 

confining units of the New Jersey Coastal Plain, which consists of 

unconsolidated gravel, sand, silt, and clay of early Cretaceous to 

Holocene age. A multilayer finite-difference model was used to simulate both prepumping steady-state conditions and transient conditions 

from 1896 through 1980. Model calibration indicates that the highest 

transmissivity, greater than 10,000 feet squared per day, is in Camden 

and Gloucester Counties in the three Potomac-Raritan-Magothy aquifers; Monmouth and Ocean Counties in the middle Potomac-RaritanMagothy aquifer; in Atlantic and Cape May Counties in the confined 

Kirkwood aquifer; and in Ocean, Burlington, Atlantic, and Cape May 

Counties in the lower and upper Kirkwood-Cohansey aquifers. 

Confining-unit vertical leakance is highest, greater than IxKT3 feet 

per day, per foot, in updip areas and lowest, less than 1 x 10~5 feet per 

day, per foot, in downdip areas.

Sensitivity analyses show that the model was useful in refining initial 

estimates of transmissivity and confining-unit vertical leakance near 

the major cones of depression and that the assumptions associated with 

the lateral and downdip boundary conditions do not seriously limit the 

usefulness of the model results. However, simulated water levels near 

the major cones of depression in several aquifers are fairly sensitive to 

parts of the model framework, including confining-unit characteristics 

along the outcrop of the Potomac-Raritan-Magothy aquifers, the updip 

limit of the confined Kirkwood aquifer, and the downdip limit of the 

upper and lower sand units of the Englishtown aquifer system.

Calibration and sensitivity analyses also show that aquifer storage 

coefficients are about IxlO"4 , except in downdip areas of the PotomacRaritan-Magothy aquifers, where they may be as much as eight times 

higher. Confining-unit specific storage is about 6xlO~6 per foot. Areas 

near the center of the major cones of depression in the PotomacRaritan-Magothy, Englishtown, Wenonah-Mount Laurel, andKirkwoodCohansey aquifers approximated steady-state conditions in 1981. However, downdip and offshore areas are under transient-flow conditions. 

Simulated changes in water levels along the saltwater-freshwater 

interface boundary (the occurrence of ground water with greater than 

10,000 milligrams per liter chloride concentrations) indicate that the 

lower Potomac-Raritan-Magothy aquifer and the confined Kirkwood 

aquifer have the greatest potential for movement of the interface. 

However, simulated hydraulic gradients within the aquifers near the 

interface boundary cannot be used to quantify movement of the 

interface. The simulated sources of water to wells in 1978 included 3 

percent from aquifer storage, 3 percent from boundary flows, 4

percent from the ocean and bays, and 90 percent from decreased 

discharge to or increased recharge from streams; that is, from a 

reduction in streamflow.

The prepumping regional flow system recharged in upland areas in 

Mercer, Middlesex, and western Monmouth Counties; in western 

Ocean and central Burlington Counties; and in central Gloucester and 

Camden Counties and discharged to the Atlantic Ocean, Delaware 

River, Delaware Bay, Raritan Bay, and to large rivers in the Coastal 

Plain. Under pumping conditions, regional cones of depression formed 

in the three Potomac-Raritan-Magothy aquifers and in the Englishtown 

aquifer, Wenonah-Mount Laurel aquifer, and the confined Kirkwood 

aquifer.

INTRODUCTION

The New Jersey Coastal Plain is a major source of 

ground water for the southern half of New Jersey and is 

part of the northern Atlantic Coastal Plain aquifer system, which extends from Long Island, N.Y., to the 

southeast boundary of North Carolina. The New Jersey 

Coastal Plain covers an area of about 4,200 square miles 

(mi2). Coastal Plain sediments are a southeastwardthickening wedge of unconsolidated gravel, sand, silt, 

and clay of Early Cretaceous to Holocene age. These 

sediments are more than 6,500 feet thick in southern 

Cape May County and are underlain primarily by Precambrian bedrock (Zapecza, 1984, p. 6).

Withdrawals from the New Jersey Coastal Plain 

aquifers were more than 350 million gallons per day 

(Mgal/d) in 1980 (Vowinkel, 1984, p. 7). Regional cones of 

depression are present in six major aquifers, and water 

levels have declined in one aquifer, to an altitude of more 

than 240 feet below sea level (Walker, 1983). Declines 

in water levels have increased the potential for movement of saltwater into freshwater aquifers; for movement of contaminants into, within, and between aquifers; 

and for permanent decreases in stream baseflow. 

These problems result from local and regional changes 

in the ground-water flow system. Effective resource

Hi
H2 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

management, which minimizes these problems, requires 

definition of the regional hydrogeologic framework and 

flow system.

PURPOSE AND SCOPE

The study that generated this report is one of a series 

that comprises the U.S. Geological Survey's Regional 

Aquifer Systems Analysis (RASA) program (described 

in the Foreword). This study is part of the northern 

Atlantic Coastal Plain RASA whose objectives include a 

complete description of the hydrogeologic framework, 

geochemistry of the ground water, and simulation of 

predevelopment and present ground-water flow conditions by digital models. The purpose of this report is to 

describe the prepumping and transient flow systems in 

the New Jersey Coastal Plain aquifer system as part of 

the New Jersey RASA program. Specifically, this report 

describes (1) the conceptual hydrogeologic model of the 

stressed and unstressed flow systems, (2) the methods 

and approach used in simulating flow, and (3) the results 

and conclusions of the flow simulations. The simulation of 

ground-water flow in the New Jersey Coastal Plain was 

coordinated with RASA modeling studies in the other 

States within the northern Atlantic Coastal Plain and 

with a regional RASA modeling study. The regional 

RASA model simulated ground-water flow in the entire 

northern Atlantic Coastal Plain by incorporating data 

from modeling studies in Long Island, N.Y., New Jersey, Delaware, Maryland, Virginia, and North Carolina. 

As part of the regional RASA, the New Jersey study 

area is adjacent to the Long Island, N.Y., study area to 

the northeast and the Delaware-Maryland RASA study 

area to the southwest. This report describes the methodology and results of the digital simulation of groundwater flow in the New Jersey Coastal Plain.

As part of the New Jersey RASA project, data on 

aquifer and confining-unit characteristics and on pumpage and water levels from 1918 through 1980 were 

compiled for the entire New Jersey Coastal Plain. The 

hydrogeologic framework of the New Jersey Coastal 

Plain has been described by Zapecza (1984). The framework report describes the sequence of aquifers and 

confining units and includes thickness maps of the aquifers and confining units and structure contour maps of 

the tops of the aquifers. Aquifer and confining-unit 

characteristics are summarized in this report. Pumpage 

and water-level data are presented by Zapecza, Voronin, 

and Martin (1987).

These data were incorporated into a digital model of 

the ground-water flow system, and flow was simulated 

for prepumping steady-state conditions (pre-1896) and 

transient conditions from 1896 through 1980. The 

ground-water flow system in sediments of the New

Jersey Coastal Plain and in offshore sediments that 

contain water with less than 10,000 milligrams per liter 

(mg/L) chloride concentration was analyzed.

LOCATION AND EXTENT

The New Jersey Coastal Plain is about one-fifth of the 

northern Atlantic Coastal Plain and is shown in figure 1. 

The emerged part of the New Jersey Coastal Plain 

extends from the Fall Line, the northwestern limit of the 

Coastal Plain sediments, to the Atlantic Ocean in the 

southeast, and from the Raritan Bay in the northeast, to 

the Delaware Bay in the southwest. The Delaware River 

overlies Coastal Plain sediments near the Fall Line 

between northern Burlington County and western Salem 

County.

The study area shown in figure 1 covers about 9,000 

mi2 and extends from the Fall Line to about 20 miles (mi) 

offshore in the southeast. The area extends from Raritan 

Bay to the center of Delaware Bay. In New Jersey, the 

study area includes all of Monmouth, Burlington, Ocean, 

Camden, Gloucester, Salem, Atlantic, Cumberland, and 

Cape May Counties and parts of Middlesex and Mercer 

Counties. The model area, which is larger than the study 

area, also includes parts of New Castle County, Del., and 

Philadelphia and Buck Counties, Pa.

PREVIOUS INVESTIGATIONS

Numerous reports have been published that describe 

the hydrogeology of the Coastal Plain sediments. Table 1 

lists the major sources of data and information on well 

identification, water levels, aquifer and confining-unit 

characteristics, withdrawals, and flow-system characteristics used in this study. The publications are generally of 

four types. Data reports are a compilation of data for a 

particular area. Areal studies sometimes include compilations of data but also describe the geology and hydrology of an area. Interpretive studies quantify certain 

aspects of the ground-water flow system, such as water 

levels or aquifer thickness, as continuous characteristics 

over an area using both observed data and principles of 

hydrology. Simulation studies are similar to interpretive 

studies; however, digital modeling techniques are used to 

incorporate large amounts of data. Simulation studies 

quantify aspects of the ground-water flow system that 

are not easily quantified from observed data, such as the 

hydraulic properties of aquifers and confining units and 

the response of the aquifer system to withdrawals.

Investigations of New Jersey Coastal Plain aquifers 

consisted primarily of areal studies from the late 1920's 

to the early 1970's. Simulation studies began in the 

mid-1970's and generally were analyses of limited parts
INTRODUCTION H3

41° -

38° -

37

FIGURE 1. Location of study area.
H4 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

TABLE I. Previous hydrogeologic investigations

Reference Area or subject

AREAL STUDIES

Anderson and Appel, 1969 ................ Ocean County.

Barksdale and others, 1943................ Middlesex County.

Barksdale and others, 1958................ Lower Delaware River basin.

Clark and others, 1968 .................... Atlantic County.

Farlekas, Nemickas, and Gill 1976 ........ Camden County.

Gill, 1962a................................. Cape May County.

Gill, 1959.................................. Cape May Peninsula.

Greenman and others, 1961 ............... Southeastern Pennsylvania.

Hardt and Hilton, 1969.................... Gloucester County.

Jablonski, 1968............................ Monmouth County.

Nichols, 1977b............................. Northern Coastal Plain (Englishtown aquifer).

Rhodehamel, 1973......................... Mullica River basin, central Coastal Plain.

Rooney, 1971.............................. Cumberland County.

Rosenau and others, 1969 ................. Salem County.

Rush, 1968................................ Burlington County.

Vecchioli and Palmer, 1962................ Mercer County. ______________________________

_______________________________DATA REPORTS AND INTERPRETIVE STUDIES_________________________

Eckel and Walker, 1986................... 1983 Coastal Plain water levels.

Gill and Farlekas, 1976.................... Potomac-Raritan-Magothy aquifer system geohydrologic maps.

Gill, 1962b................................. Well records and logs, Cape May County.

Hardt, 1963 ............................... Public water supplies, Gloucester County.

Jablonski, 1959 and 1960 .................. Well records, Monmouth County.

Meisler, 1980.............................. Occurrence of salty ground water in the northern Atlantic Coastal Plain.

Rush, 1962 ................................ Well records and water quality in Burlington County.

Thompson, 1928, 1930, 1932............... Ground-water supplies of the Atlantic City region, Asbury Park area, and

	Camden area. 

Vowinkel, 1984............................ Generalized withdrawal data-management system.

Vowinkel and Foster, 1981................ Generalized geohydrology of the Coastal Plain.

Walker, 1983.............................. 1978 Coastal Plain water levels.

Zapecza, 1984 ............................. Hydrogeology of the Coastal Plain.

Zapecza, Voronin, and Martin, 1987....... Coastal Plain water levels and withdrawals._________________

__________________________________________SIMULATION STUDIES____________________________________

Farlekas, 1979 ............................ Farrington aquifer, northern Coastal Plain.

Harbaugh and Tilley, 1984 ................ Water-table aquifer, Mullica River basin, central Coastal Plain.

Luzier, 1980, and Harbaugh, Luzier, and

Stellerine, 1980 ......................... Potomac-Raritan-Magothy aquifer system, New Jersey Coastal Plain.

Nemikas, 1976 ............................ Wenonah Mount Laurel aquifer, northern Coastal Plain.

Nichols, 1977a............................. Englishtown aquifer, northern Coastal Plain.

of the ground-water flow system using a finite-difference 

simulation of two-dimensional flow. Previous simulation 

studies have included analyses of the Farrington, 

Englishtown, and Wenonah-Mount Laurel aquifers and 

the Potomac-Raritan-Magothy aquifer system (table 1).

ACKNOWLEDGMENTS

Thanks are given to the New Jersey Department of 

Environmental Protection for its assistance in supplying 

withdrawal and well data. Thanks are also given to the 

many municipalities, industries, and individuals that 

provided withdrawal and water-level information to the 

New Jersey Department of Environmental Protection 

and the U.S. Geological Survey.

CONCEPTUAL HYDROGEOLOGIC MODEL

The New Jersey Coastal Plain sediments are a seawarddipping wedge of alternating layers of sand, silt, and clay 

overlying crystalline basement. Cretaceous and Tertiary 

sediments generally strike northeast-southwest and dip 

10 to 60 feet per mile (ft/mi) to the southeast, whereas 

overlying Quaternary sediments, where present, are flat 

lying (Zapecza, 1984). The Coastal Plain deposits thicken 

downdip from a feather edge at the Fall Line to more 

than 6,500 feet in southern Cape May County (Gill and 

Farlekas, 1976).

The Coastal Plain sediments have been subdivided into 

a sequence of aquifers and confining units based on the 

general hydraulic properties of the sediments. The geologic and hydrogeologic units are listed in table 2. The
CONCEPTUAL HYDROGEOLOGIC MODEL H5

TABLE 2. Geologic and hydrogeologic units of the New Jersey Coastal Plain and model units used in this study

SYSTEM

Quaternary

Tertiary

Cretaceous

SERIES

Holocene

Pleistocene

Miocene

Eocene

Paleocene

Upper 

Cretaceous

Lower 

Cretaceous

Pre-Cretaceous

GEOLOGIC 

UNIT

Alluvial 

deposits

Beach sand 

and gravel

Cape May 

Formation

Pensauken 

Formation

Bridgeton 

Formation

Beacon Hill 

Gravel

Cohansey Sand

Kirkwood 

Formation

Piney Point 

Formation

Shark River 

Formation

Manasquan 

Formation

Vincentown 

Formation

Hornerstown 

Sand

Tinton Sand

Red Bank Sand

Navesink 

Formation

Mount Laurel 

Sand

Wenonah 

Formation

Marshalltown 

Formation

Englishtown 

Formation

Woodbury Clay

Merchantville 

Formation

Magothy 

Formation

Raritan 

Formation

Potomac 

Group

Bedrock

HYDROGEOLOGIC

UNIT

Undifferentiated

K-C aq. 

sys. 1

Kirkwo 

Cohans 

aquife 

system

3dey

Confining unit

Confining unit

Atlantic City 

800-foot sand

Piney Point 

aquifer

01 

J3 

D5

C 

C

" Vincentown 

S aquifer

o

0.

E 

o 

o

Red Bank 

sand

Wenonah-Mount 

Laurel aquifer

MarshalltownWenonah 

confining unit

Englishtown 

aquifer system

MerchantvilleWoodbury 

confining unit

Upper 

<o. CB aquifer

' -"=, Conf un

tr^E Middle 

" >-£ aquifer

i o >- Conf un

0 cn w .

 £ ro Lower 

°-^ aquifer

Bedrock 

confining unit

MODEL UNITS

UPDIP

Upper Kirkwood-Cohansey aquifer 

(A9)

DOWNDIP

Holly Beach aquifer (A10)

Cape May confining unit (C9)

Upper Kirkwood-Cohansey aquifer (A9)

Upper Kirkwood-Cohansey aquifer (A9)

Lower Kirkwood-Cohansey 

aquifer (AS)

.. - . . -.. . . -

Confining unit overlying the Rio Grande 

water-bearing zone (C8)

Confined Kirkwood aquifer (A8)

Basal Kirkwood confining unit (C7)

Piney Point aquifer (A7)

Vincentown-Manasquan confining unit (C6)

Vincentown aquifer (A6)

Navesink-Hornerstown confining unit (C5|

Wenonah-Mount Laurel aquifer (A5)

Marshalltown-Wenonah confining unit (C4)

Englishtown aquifer (A4)

Merchantville-Woodbury confining unit (C3)

Upper Potomac-Raritan-Magothy aquifer (A3)

Confining unit between the middle and upper Potomac-Raritan-Magothy aquifers (C2)

Middle Potomac-Raritan-Magothy aquifer (A2)

Confining unit between the lower and middle Potomac-Raritan-Magothy aquifers (CD

Lower Potomac-Raritan-Magothy aquifer (A1)

1 Kirkwood-Cohansey aquifer system

2 Rio Grande water-bearing zone

n Indicates adjacent geologic or hydrogeologic 

unit not present

Modified from Zapccza (1984, table 2) and 

Seaber (1965, table 3).
H6 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

NW ENGLISHTOWN 

AQUIFER (A4)

SE

FALL LINE NAVESINK-HORNERSTOWN 

CONFINING UNIT(C5)

UPPER KIRKWOOD-COHANSEY 

AQUIFER (A9)

CONFINING UNIT OVERLYING

THE RIO GRANGE 

WATER-BEARING ZONE (C8) HOLLY BEACH 

AQUIFER (A10)

ATLANTIC 

OCEAN

ESTUARINE CLAY 

CONFINING UNIT (C9]

EXPLANATION

| | AQUIFER Numbers refer to 

model units listed in table 2

CONFINING UNIT Numbers refer to 

model units listed in table 2

Not to scale

FIGURE 2. Generalized hydrogeologic section of the New Jersey Coastal Plain.

aquifer and confining-unit designations do not necessarily correspond to time- or rock-stratigraphic designations. The New Jersey Coastal Plain aquifers are 

composed predominantly of sand but also include interbedded silts and clays. The confining units are composed 

predominantly of clay and silt with minor amounts of 

sand. Most of these units crop out near the Fall Line in 

irregular bands parallel to the strike. The Coastal Plain 

sediments were modeled as 10 major aquifers and 9 

intervening confining units. These model units are identified in table 2 and in the generalized hydrogeologic 

section of the Coastal Plain in figure 2.

Recharge to the New Jersey Coastal Plain is by 

infiltration of precipitation, leakage from surface-water 

bodies, and lateral flow from adjacent States. Water is 

discharged from the aquifers as flow to surface-water 

bodies, evapotranspiration, withdrawals from wells, and 

lateral flow to adjacent States. Previous investigations 

have reached the general conclusion that the major 

sources of water to wells are induced infiltration from 

surface-water bodies, decreased flow to surface-water 

bodies, increased flow from adjacent States, decreased 

flow to adjacent States, and water released from storage. 

Minor sources of water to wells, sources that are important only locally, are increased infiltration of precipitation and decreased evapotranspiration.

AQUIFER AND CONFINING-UNIT CHARACTERISTICS

The model framework is based on the hydrogeologic 

framework of the New Jersey Coastal Plain presented 

by Zapecza (1984). Names of geologic and hydrogeologic 

units used in the following sections describing the 

model units are from Zapecza, unless otherwise noted. 

Although the major aquifers and confining units in New 

Jersey were mapped by Zapecza, several modifications 

were necessary to adapt the hydrogeologic framework to 

a model framework. Estimates of unit thickness for areas 

not mapped by Zapecza were made for most units, and 

several units were subdivided into separate model layers. Also, some framework modifications were needed to 

ensure a compatible framework with adjacent States. 

Lithologic characteristics of the geologic units, aquifers 

and confining units, and stratigraphic nomenclature have 

been discussed by Zapecza and are not discussed in this 

report.

An informal nomenclature is used for the model units 

in this report. The names used in this report were 

selected partly for convenience and are not always 

descriptive or exact. In many cases, an aquifer name 

represents a regional aquifer and additional local minor 

aquifers. The sediments represented by each model unit 

are described in the following sections. The aquifers and
CONCEPTUAL HYDROGEOLOGIC MODEL H7

confining units are described in order of oldest (deepest) 

to youngest (shallowest), following the order of presentation by Zapecza (1984).

The hydrogeologic characteristics of each aquifer and 

confining unit are also described in the following sections. Data on aquifer transmissivity, hydraulic conductivity, and storage coefficient are shown in table 3. Data 

on vertical hydraulic conductivity of confining units are 

given in table 4. Structure contour maps of the tops of 

the confined aquifers and thickness maps of the confining 

units are shown in figures 3 through 20.

Data presented in tables 3 and 4 are compiled from the 

literature of previous estimates of the hydraulic characteristics of aquifers and confining units within the New 

Jersey Coastal Plain. However, these data are not 

internally consistent because they are from many different methods of collection and analysis and may not 

represent actual hydraulic characteristics because of the 

method of collection or analysis. Many early estimates of 

transmissivity may be as much as 25 percent too high if 

aquifer-test data from a leaky confined aquifer were 

analyzed as though the data were from a nonleaky 

aquifer (Harold Meisler, oral commun., 1985). This is 

probably true of transmissivity data from Barksdale and 

others (1958), Rush (1968), Jablonski (1968), and Gill 

(1962a). Many laboratory analyses of confining-unit 

hydraulic conductivity were made on disturbed and 

repacked cores (G.M. Farlekas, oral commun., 1985). 

Results of such analyses are given in Farlekas and others 

(1976). Some of the data presented in tables 3 and 4 are 

shown for aquifers or confining units different from those 

given in the original reference. The unit names given in 

the tables are based on the model framework.

Only freshwater flow has been simulated, and, for the 

purpose of this report, freshwater is water with chloride 

concentrations less than 10,000 mg/L. Therefore, only 

sediments containing water with less than 10,000 mg/L 

chloride concentrations are represented in figures 3 

through 20 and discussed in the following sections. The 

estimated locations of 10,000 mg/L chloride concentrations within the aquifers are based on data presented by 

Meisler (1981) and are referred to in this report as the 

downdip limit of freshwater within the aquifers. The 

assumptions associated with choosing 10,000 mg/L chloride concentrations as the limit of fresh ground water are 

discussed further in the section on boundary conditions.

The maps shown in figures 3 through 20 are approximate representations of the Coastal Plain hydrogeologic 

framework. In several areas, altitudes and thicknesses 

were estimated from sparse geophysical logs. For most 

units, altitudes and thicknesses in offshore areas are 

estimated from approximated contour lines in onshore 

areas.

LOWER POTOMAC-RARITAN-MAGOTHY AQUIFER

The lowermost Coastal Plain aquifer modeled is the 

lower aquifer of the Potomac-Raritan-Magothy aquifer 

system. This aquifer is referred to as the lower PotomacRaritan-Magothy aquifer and is designated Al in the 

model. It is present everywhere in Camden County and 

in parts of Monmouth, Ocean, Burlington, Atlantic, 

Gloucester, and Salem Counties. This aquifer is underlain by crystalline basement or weathered basement 

rock. The configuration of the bedrock surface is shown 

by Zapecza (1984, pi. 1).

Structure contours of the top of the lower PotomacRaritan-Magothy aquifer are shown in figure 3. Near the 

Delaware River in northwestern Salem, Gloucester, and 

Camden Counties, the altitude of the top of the aquifer is 

the same as that shown by Zapecza (1984, pi. 6). In 

downdip areas and in the eastern Coastal Plain, the top 

of the aquifer is estimated from available geophysical 

logs. Generally, in these areas, model unit Al represents 

the sand beds of the lower third of the undifferentiated 

Potomac-Raritan-Magothy aquifer system.

The altitude of the top of the lower Potomac-RaritanMagothy aquifer ranges between 100 feet below sea level 

near the Delaware River to 3,200 feet below sea level 

near Barnegat Light in Ocean County and to the east 

beneath the Atlantic Ocean. The aquifer sediments may 

extend further downdip than shown on figure 3, but the 

area modeled is limited to the part of the aquifer containing freshwater as shown by the estimated occurrence of 

10,000 mg/L chloride concentrations.

The aquifer is 75 feet thick near the Delaware River 

and is thickest along the 10,000 mg/L chloride boundary. 

Along the southern boundary, the aquifer is 450 feet 

thick in eastern Ocean County, 600 feet thick in southern 

Gloucester County, and 500 feet thick in eastern Salem 

County.

The lower Potomac-Raritan-Magothy aquifer is continuous into Delaware and is in the lower part of the 

Potomac Formation in that State (D. A. Vroblesky, written commun., 1985). The aquifer extends south of Long 

Island, N.Y., but is not part of the sediments found in 

New York (Henry Trapp, written commun., 1985). The 

lower aquifer does not crop out in the New Jersey 

Coastal Plain and is overlain entirely by the confining 

unit between the lower and middle Potomac-RaritanMagothy aquifers.

Aquifer-test analyses indicate that the transmissivity 

of the lower Potomac-Raritan-Magothy aquifer ranges 

generally from 2,300 to 9,100 feet squared per day (ft2/d), 

and possibly as high as 16,600 ft2/d (table 3). Storage 

coefficients from these tests range from 3.3xlO~5 to 

1.5xHT3 . Aquifer test data are available only for Camden and Gloucester Counties.
40°

PENNSYLVANIA FALL LINE X

Haddott Heights

Of ATLAix iC I

-WO STRUCTURE CONTOUR Shows altitude of the top 

of the lower Potomac-Raritan-Magothy aquifer. 

Dashed where approximately located. Contour 

interval 200 feet. National Geodetic Vertical Datum of 1929

10 15 KILOMETERS

a

oo

75

M 

OI-HO

£tr1> 

« >

74° 39° Altitudes in northwest Salem, Gloucester, and Camden Counties modified from Zapecza 

(1984, pi. 6). Altitudes in Delaware and Maryland from D.A. Vroblesky (written commun., 

1985). Location of 10,000 milligrams per liter chloride concentrations based on Meisler 

(1981, fig. 4).

M

Oo o

FIGURE 3. Altitude of the top of the lower Potomac-Raritan-Magothy aquifer (model unit Al).
40

£ENlNSYLVAN! \ FALLLINE f ^~^-^ x^^_J^~- >>

1 CUMBERLAND 

(>tt

Cfi

<lflS

700 LINE OF EQUAL THICKNESS OF THE CONFINING UNIT

BETWEEN THE LOWER AND MIDDLE POTOMAC-RARITANMAGOTHY AQUIFERS Dashed where approximately located 

Interval 50 and 100 feet

75

40°

74° 39° Thickness in northwest Salem, Gloucester, and Camden Counties modified from Zapecza 

(1984, pi. 6). Thickness in Delaware and Maryland from D.A. Vroblesky (written commun., 

1985). Location of 10,000 milligrams per liter chloride concentrations based on Meisler 

(1981, fig. 4).

FIGURE 4. Thickness of the confining unit between the lower and middle Potomac-Raritan-Magothy aquifers (model unit Cl).

O 

fe!T)

IOo

H 

O tr1 O Oo 

offi<£>
H10 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

 a

I

f

a;

1
40° 75°

39°75°

10 15 MILES

0 5 10 15 KILOMETERS

EXPLANATION

 200-- LINE OF EQUAL THICKNESS OF THE CONFINING UNIT

BETWEEN THE MIDDLE AND UPPER POTOMAC-RARITANMAGOTHY AQUIFERS Dashed where approximately located. 

Interval 50 feet

74°

40°

O OO

W *i o 

» o o

H

o r1 o 

o

HH

O

go o

H

74° 39° Thickness in northwest Salem, Gloucester, Camden, Burlington, Ocean, and Monmouth Counties 

modified from Zapecza (1984, pi. 9). Thickness in Delaware and Maryland from D.A. Vroblesky 

(written commun., 1985). Location of 10,000 milligrams per liter chloride concentrations based on 

Meisler(1981,fig.4).

FIGURE 6. Thickness of the confining unit between the middle and upper Potomac-Raritan-Magothy aquifers (model unit C2). ffi
H12 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

1
39 C

75°

APPROXIMATE SEAWARD LIMIT OF FRESHWATER IN UNDERLYING AQUIFERS AS DELINEATED 

BY CHLORIDE CONCENTRATIONS OF 10,000 MILLIGRAMS PER LITER

EXPLANATION

5 10 15 MILES

i____i____i

0 5 10 15 KILOMETERS

__200 LINE OF EQUAL THICKNESS OF THE MERCHANTVILLEWOODBURY CONFINING UNIT Dashed where 

approximately located. Interval 50 feet

74°

40°

O O 55 

Oto

O OO

a

74° 39° Thickness in northwest Salem, Gloucester, Camden, Burlington, and Monmouth Counties 

modified from Zapecza (1984, pi.12). Thickness in Delaware and Maryland from D.A. Vroblesky 

(written commun., 1985). Location of 10,000 milligrams per liter chloride concentrations based on 

Meisler(1981,fig.4).

FIGURE 8. Thickness of the Merchantville-Woodbury confining unit (model unit C3).
ffi

PENNSYLVANIA FALL LINE

-WO .__MONMOUTH

\

BURLINGTON 

-800

 -7,200 _ _ _ - 1,400 

OUTCROP AREA OF THE ENGLISHTOWN FORMATION 

IN NEW JERSEY

 -200 STRUCTURE CONTOUR Shows altitude of the top

of the Englishtown aquifer. Dashed where approximately 

located. Contour interval 100 and 200 feet. 

National Geodetic Vertical Datum of 1929

0 5 10 15 MILES

i i i

0 5 10 15 KILOMETERS

75

H 

O

I 

1

H CO

H

CO

hH

CO

OO 

O

74° 39° Altitudes in New Jersey modified from Zapecza (1984, pi. 13). Altitudes in Delaware and 

Maryland from D.A. Vroblesky (written commun., 1985).

FIGURE 9. Altitude of the top of the Englishtown aquifer (model unit A4).
40° 75°

39'

/

75°

APPROXIMATE SEAWARD LIMIT OF FRESHWATER IN UNDERLYING AQUIFERS AS DELINEATED 

BY CHLORIDE CONCENTRATIONS OF 10,000 MILLIGRAMS PER LITER

0 5 10 15 MILES

| i i____i

0 5 10 15 KILOMETERS

EXPLANATION

-20 - LINE OF EQUAL THICKNESS OF THE MARSHALLTOWNWENONAH CONFINING UNIT Dashed where approximately located. Interval 20 feet

74°

40°

3

aO

O

w

Ot-1O

OI I0

gO G 

Hr

74° 39°

ThicknQSS in araas ovGrlying thG Englishtown aquifgr in NGW JGTSGV modifiGd from ZapGcza 

(1984, pi. 15). ThicknGss in DGlaware and Maryland from D.A. VroblGsky (writtGn commun., 1985). 

Location of 10,000 milligrams per litGr chloridG concGntrations basGd on MeislGr (1981, fig. 4).

FIGURE 10. Thickness of the Marshalltown-Wenonah confining unit (model unit C4).

ffi i i 

Cn
H16 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

I

o g e C/J ^. S
40° 75°

39°

75°

74°

EXPLANATION

700- - LINE OF EQUAL THICKNESS OF THE NAVESINKHORNERSTOWN CONFINING UNIT Dashed where 

approximately located. Interval 20 and 40 feet

40°

o 

o

o3o » 

o

o

o

o

74° 39° Thickness in Delaware and Maryland from D.A. Vroblesky (written commun., 1985). 

Location of 10,000 milligrams per liter chloride concentrations based on Meisler 

(1981, fig. 4).

FIGURE 12. Thickness of the Navesink-Hornerstown confining unit (model unit C5). ffi
wI 1

oo

Ef'if: SYLVAN! A FALL LINE ,-

I IGLOUCESTER A

' CUMBERLAND 

Wily a/05 /

EXPLANATION 

OUTCROP AREA OF THE VINCENTOWN FORMATION IN NEW JERSEY

WO-- STRUCTURE CONTOUR Shows altitude of the top of the Vincentown 

aquifer. Dashed where approximately located. Contour interval 100 feet 

National Geodetic Vertical Datum of 1929

75'

O> >

O

f> 

,O

Si

CO

I-H

COI

s: 

o 

»=

OOO

>I

74° 39° Altitudes in New Jersey modified from Zapecza (1984, pi. 19). Altitudes in Delaware and Maryland 

from D.A. Vroblesky (written commun., 1985).

FIGURE 13. Altitude of the top of the Vincentown aquifer (model unit A6).
40

EXPLANATION

LYING AQUIFERS AS DELINEATED 

R LITER 700- - LINE OF EQUAL THICKNESS OF THE VINCENTOWNMANASQUAN CONFINING UNIT Dashed where 

approximately located. Interval 100 feet 0 5 10 15 MILES

i i i

0 5 10 15 KILOMETERS

40°

o oo

I

f a

oQ

O 0

HH

o

o

G

74° 39° Thickness in Delaware and Maryland from D.A. Vroblesky (written commun., 1985). 

Location of 10,000 milligrams per liter chloride concentrations based on Meisler 

(1981, fig. 4).

FIGURE 14. Thickness of the Vincentown-Manasquan confining unit (model unit C6).

CO
8

40° 75°

/ M*y / v

PENNSYLVANIA FALLLINE f

SALEM *} GLOUCESTER JCAMDEN

MONMOUTH

39C

_ 

' 

_ _ 

- - -700

-eoo _ _ _ _ 0 5 10 15 MILES

| i i____I

0 5 10 15 KILOMETERS

EXPLANATION

-700 STRUCTURE CONTOUR Shows altitude of the top

of the Piney Point aquifer. Dashed where approximately 

located. Contour interval 100 feet. National Geodetic 

Vertical Datum of 1929

74°

40°

H 

Oh-H

O

 ocj p i ^

MGOO S3

M

oo 

oI

74° 39° Altitudes in New Jersey modified from Zapecza (1984, pi. 19). Altitudes in Delaware 

and Maryland from D.A. Vroblesky (written commun., 1985).

FIGURE 15. Altitude of the top of the Piney Point aquifer (model unit A7).
40° 75°

39°

PENNSYLVANIA FALL LINE

75°

/

\

- ..J UNDERLYING AQUIFERS AS DELINEATED 

10,000 MILL/GRAMS PER LITER

0 5 10 15 MILES

0 5 10 15 KILOMETERS

\

EXPLANATION

100 LINE OF EQUAL THICKNESS OF THE BASAL KIRKWOOD 

CONFINING UNIT Dashed where approximately located. 

Interval 20 feet

74°

40r

O O

O

M

o o

M O t-1 O OI Io

74° 39° Thickness in Delaware and Maryland from D.A. Vroblesky (written commun., 1985). Location of 

10,000 milligrams per liter chloride concentrations based on Meisler (1981, fig. 4).

FIGURE 16. Thickness of the basal Kirkwood confining unit (model unit C7).
H22 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

/ / / J //' 

' I / I, // / 8

OS §

O

a 

I
40° 75°

PENNSYLVANIA FALL LINE <"

/

\ 5 V SALEM x, GLOUCESTER /CAMDEN

JLVV

YORK

MONIVIOUTH

39C

EXPLANATION

700 LINE OF EQUAL THICKNESS OF THE CONFINING UNIT

OVERLYING THE RIO GRANDE WATER-BEARING ZONE 

Dashed where approximately located. 

Interval 50 feet

750-

75° 5 10 15 KILOMETERS

74°

40°

a ^ oEd 

o 

o

H 

O 

f 

O

oh-H

o

o

oH 

f

74° 39° Thickness in Delaware and Maryland from D.A. Vroblesky (written commun., 1985). 

FIGURE 18. Thickness of the confining unit overlying the Rio Grande water-bearing zone (model unit C8).

a

co
40° 75°

39C

PENNSYLVANIA FALL LINE

UPDIP LIMIT OF OVERLYING CONFINING! UNITJC9) ___ ' Cape May <

/ Sewell \ 

X Point

--50 

\

700-

-100

 200-

75° X

EXPLANATION

 -200 STRUCTURE CONTOUR Shows altitude of the top

of the confined part of the Kirkwood-Cohansey aquifer. 

Dashed where approximately located. Contour interval 

50 and 100 feet. National Geodetic Vertical Datum of 1929

5 10 15 MILES

-300- 0 5 10 15 KILOMETERS

74°

40°

H

O

&

H

Ei

H

COSo

o 

»

HwH

TJ

g2

74° 39° Altitudes in New Jersey modified from Gill (1962, fig. 16). Altitudes in Delaware 

and Maryland from D.A. Vroblesky (written commun., 1985).

FIGURE 19. Altitude of the top of the confined part of the upper Kirkwood-Cohansey aquifer (model unit A9).
40

PENNSYLVANIA FALL LINE S

39°75°

SALEM N, GLOUCESTER JCAMDEN 

X

0 5 10 15MILES

i i i

MONMOUTH

v

BURLINGTON

OCEAN

ATLANTIC (

/

^/MITOFCONFININGJJNJI 25

 25 

i vTTv 

YORK

EXPLANATION

25 - - LINE OF EQUAL THICKNESS OF THE ESTUARINE CLAY 

CONFINING UNIT Dashed where approximately located. 

Interval 25 feet

74°

40°

O OO 

Hf ffi K! 

o 

» o o

H 

O

s

o

HH

O

go

D

74° 39° Thickness in Cape May County modified from Gill (1962a, fig. 8). Thickness in 

Delaware and Maryland from D.A. Vroblesky (written commun., 1985).

FIGURE 20. Thickness of the estuarine clay confining unit (model unit C9).

ffi toCn
H26 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

TABLE 3. Summary of data on transmissivity, hydraulic conductivity, and storage coefficient for aquifers in the New Jersey Coastal Plain 

Location: Shown on maps of altitude of the top of the aquifers (figs. 3, 5, 7, 9, 11, 13, 15, 17, and 19).

Transmissivity

//»! 2/J\ (fr/d)

Hydraulic 

conductivity

(ft/d)

Storage 

coefficient

(dimensionless)

Type Location Reference

LOWER POTOMAC-RARITAN-MAGOTHY AQUIFER (Al)

2,300- 6,700

3,200- 3,700

'8,300

2 16,600

6,800- 9,100

36,000-35,000

350

240

140-190

1.0xlO"4 to 3.5xlO"4

3.3xlO~5 to 1.5xlO"3

1.2xlO~3

1.0xlO~3

9.0xlO"5 to 1.7xlO~4

8xlO~5 to

8xlO~3

Aquifer test

Aquifer test

Aquifer test

Aquifer test

Aquifer test

Model results

Camden, Camden County

Camden, Camden County

Camden, Camden County

Haddon Heights, Camden

County.

Westville, Gloucester

County.

New Jersey Coastal Plain

Farlekas and others (1976,

Farlekas and others (1976,

Barksdale and others (1958

Barksdale and others (1958

Barksdale and others (1958

Luzier (1980, p. 44).

p. 38).

p. 38).

, P- 97).

, P- 97).

, P- 97).

MIDDLE POTOMAC-RARITAN-MAGOTHY AQUIFER (A2)

6,200-12,000

22,000

28,200-68,600

13,100-17,400

20,000

6,300

'8,300

13,400

6,700-10,200

550- 1,900

42,300- 9,000

42-16,800

36,000-35,000

130-270

200

217-290

200

200

350

2,000

79-119

32-88

105

_

2.1xl(T4

6.0xlO~2

l.lxlO~4 to

5.8xl(T4

1.0xlO~4 to 2.4xlO"4

1.5xlO~4

1.5x10"*

1.2xlO"3

l.GxlO"3

3.7xlO"5 and 8.6xlO"5

4.0xlO"5 to 8.1X10"2

5.8xlO~4 to 2.4xlO~3

l.GxlO"4

8xlO~5 to

8xlO~3

Aquifer test

Aquifer test

Aquifer test

Aquifer test

Aquifer test

Aquifer test

Aquifer test

Aquifer test

Aquifer test

Aquifer test

Aquifer test

Model results

Model results

Burlington Township,

Burlington County.

Burlington, Burlington

County.

Palmyra, Burlington County

Beverly, Burlington County

Riverton, Burlington County

Gibbstown, Gloucester

County.

Camden, Camden County

Parlin, Middlesex County

Parlin, Middlesex County

Barber, Middlesex County

Old Bridge, Middlesex

County.

Southeastern Mercer,

Middlesex, Monmouth, and

northern Ocean Counties.

New Jersey Coastal Plain

Rush (1968, p. 33).

Rush (1968, p. 33).

Rush (1968, p. 33).

Rush (1968, p. 33).

Barksdale and others (1958

Barksdale and others (1958

Barksdale and others (1958

Barksdale and others (1958

Barksdale and others (1958

Barksdale and others (1958

Barksdale and others (1958

, p. 97).

, p. 97).

, P- 97).

, p. 97).

, p. 97).

, P. 97).

, p. 97).

Farlekas (1979, p. 32 and 51).

Luzier (1980, p. 44).

UPPER POTOMAC-RARITAN-MAGOTHY AQUIFER (A3)

500- 3,000

216,600

42,300- 9,000

36,000-35,000

240

1.0x10"*

l.OxlO"3

5.8xlO~4 to 2.4X10"3

8xlO~5 to

8xlO~3

Aquifer test

Aquifer test

Aquifer test

Model results

Delmarva Peninsula

Haddon Heights, Camden

County.

Old Bridge, Middlesex

County.

New Jersey Coastal Plain

Gushing and others (1973, p. 41).

Barksdale and others (1958

Barksdale and others (1958

Luzier (1980, p. 44).

, P. 97).

, P- 97).

ENGLISHTOWN AQUIFER (A4)

2,100

1,300

1,100

1,100

400- 2,400

27

45-67

12

15

2.7xlO~4

lxlO~4

7.6xKT5

2.2x10"*

Aquifer tests

Aquifer tests

Laboratory

tests.

Aquifer test

Aquifer test

Model results

Clementon, Camden County

Monmouth County

Monmouth County

Allenwood, Monmouth

County.

Lakewood, Ocean County

Monmouth, Ocean, and

northern Burlington

Counties.

Farlekas and others (1976,

Jablonski (1968, p. 53).

Jablonski (1968, p. 53).

Nichols (1977a, p. 25).

Nichols (1977a, p. 25).

Nichols (1977a, p. 26).

p. 61).
CONCEPTUAL HYDROGEOLOGIC MODEL H27

TABLE 3. Summary of data on transmissivity, hydraulic conductivity, and storage coefficient for aquifers in the New Jersey Coastal

Plain Continued

Transmissivity Hy," ,-,2/jx conductivity

(n /a> (ft/d)

Storage 

coefficient 

(dimensionless)

Type 

of data Location Reference

WENONAH-MOUNT LAUREL AQUIFER (A5)

360-1,430

360-1,400

1,200

940

17

13-19

13

19

7.0xlO~5 to 2.1xlO~4

1.5xlO~5 to 3.5xlO~4

3.5XHT4

Aquifer test

Model results

Aquifer test

Aquifer test

Bradley Beach,

Monmouth County.

Monmouth, Ocean, and

northeastern Burlington

Counties.

Salem, Salem County

Artificial Island, Salem

County.

Jablonski (1968, p. 62).

Nemickas (1976, p. 39).

Rosenau and others (1969, p. 40).

Farlekas and others (1976, p. 70).

VINCENTOWN AQUIFER (A6)

530 21 Laboratory

test.

Outcrop area between

Jacobstown and New

Egypt, Burlington County.

Rush (1968, p. 53).

PINEY POINT AQUIFER (A7)

1,200-6,000

4,100

1,000-7,000

1,400 23

2xlO~4 to

4xlO~4

3.0xlO~4

3.0xlO~4

3xlO~4

Aquifer tests

Aquifer test

Model results

Aquifer test

Delaware

Dover, Kent County,

Delaware.

Kent County, Delaware

Ancora, Camden County

Gushing, Kantrowitz, and Taylor

(1973, p. 43).

Leahy (1976, p. 10).

Leahy (1979, p. 35 and 40).

Rush (1968, p. 56).

LOWER KIRKWOOD-COHANSEY AQUIFER AND CONFINED KIRKWOOD AQUIFER (A8)

5,200-5,900

9,900-12,500

8,800-9,600

3,400-3,600

6,700

1,500

42^8

120-150

108-120

38-41

1.2xlO~4 to 2.3xlO~4

2.3xlO~4 to 2.8xlO~4

2.6xlO~4 to 2.7xlO~4

8.5xlO~5 to 9.0xlO~5

3.0xlO~4

6xlO~4

Aquifer test

Aquifer test

Aquifer test

Aquifer test

Statistical

Aquifer test

Atlantic City, Atlantic

County.

Pleasant ville, Atlantic

County.

Pleasantville, Atlantic

County.

Stone Harbor, Cape May

County.

Longport, Cape May County

Ocean Gate, Ocean County

USGS unpublished data.

Gill (1962a, p. 47).

Gill (1962a, p. 47).

Gill (1962a, p. 47).

Gill (1962a, p. 47).

Anderson and Appel (1969, p. 48).

UPPER KIRKWOOD-COHANSEY AQUIFER (A9)

16,000

20,000

12,000

5,500-^8,400

3,600-4,500

10,000

4,000

7,500

8,300

3,800

4,300

20,000

130

130

120

86-130

53-67

170

130

250

90

140

150

150

4.2xlO~4

2.2xlO~4 to 4.9xlO~4

1.2xlO~4 to 2.4xlO~4

1.0xlO~3

3xlO~4

4.4xlO~2

Aquifer test

Aquifer test

Aquifer test

Aquifer tests

Aquifer tests

Aquifer test

Aquifer test

Aquifer test

Aquifer test

Aquifer test

Aquifer test

Aquifer test

Linwood, Atlantic County

Batsto, Burlington County

Lebanon State Forest,

Burlington County.

Cape May City, Cape May

County.

Sewell's Point, Cape May

County.

Vineland, Cumberland

County.

Clayton, Gloucester County

Clayton, Gloucester County

Williamstown, Gloucester

County.

Toms River, Ocean County

Elmer, Salem County

Brotmanville, Salem County

Rhodehamel (1973, p. 55).

Rhodehamel (1973, p. 55).

Rhodehamel (1973, p. 55).

Gill (1962a, p. 49).

Gill (1962a, p. 49).

Rhodehamel (1973, p. 55).

Rhodehamel (1973, p. 55).

Rhodehamel (1973, p. 55).

Rhodehamel (1973, p. 55).

Rhodehamel (1973, p. 55).

Rhodehamel (1973, p. 55).

Rhodehamel (1973, p. 55).

1 Model unit Al or A2.

2 Model unit Al or A3.

3 Model unit Al, A2, and A3 combined.

4 Model unit A2 or A3.
H28 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

TABLE 4. Summary of vertical hydraulic-conductivity data for confining units in the New Jersey Coastal Plain 

Location: Shown on confining unit thickness maps (figs. 6, 8, 10, and 12).

Geologic unit

Vertical

hydraulic Type 

conductivity of data

(ft/d)

Location Reference

CONFINING UNIT BETWEEN THE MIDDLE AND UPPER POTOMAC-RARITAN-MAGOTHY AQUIFERS (C2)

Woodbridge Clay Member

of the Raritan Foramtion.

Woodbridge Clay Member

of the Raritan Formation.

3.6x 10~2 to Model results 8.6xlO~6

8.4xlO~2 Aquifer test

and model

results.

Southeastern Middlesex

County to northern

Monmouth County.

South Brunswick Township,

Middlesex County.

Farlekas (1979, p. 36).

Farlekas (1979, p. 12).

MERCHANTVILLE-WOODBURY CONFINING UNIT (C3)

Merchantville Formation

Merchantville Formation

and Woodbury Clay.

Merchantville Formation

and Woodbury Clay.

Merchantville Formation

and Woodbury Clay.

Merchantville Formation

and Woodbury Clay.

Woodbury Clay

Englishtown Formation

clayey silt lithofacies.

1.0xl(T4 to Laboratory

4.0xlO~4 test.

3. 7 x 10~6 to Laboratory

G.OxlCT5 test.

3.6xlO~6 to Laboratory

1.4xlO~5 test.

4.3xlO~6 Model results

8.6xlO~7 to Model results 1.7xlO~3

1.0xl(T4 to Laboratory

3.0xlO~2 test.

1.9xl(T6 Laboratory

test.

Winslow Township, Camden

County.

Fort Dix, Burlington

County.

Lakewood, Ocean County

Northern Coastal Plain

New Jersey.

New Jersey Coastal Plain

Winslow Township, Camden

County.

Lakewood, Ocean County

Farlekas and others (1976, p.

133-134).

Nichols (1977b, p. 58).

Nichols (1977a, p. 58).

Nichols (1977a, p. 76).

Luzier (1980, p. 29).

Farlekas and others (1976, p.

133-134.

Nichols (1977a, p. 58).

MARSHALLTOWN-WENONAH CONFINING UNIT (C4)

Marshalltown Formation

Marshalltown Formation

Marshalltown Formation

Marshalltown Formation

and Wenonah Formation.

Marshalltown Formation

and Wenonah Formation.

2.6xlO~4 Laboratory

test.

1.3 xlO" 1 Laboratory

test.

4.9xlO~4 Laboratory

test.

5.7xlO~6 to Laboratory

2.4xl(T5 test.

1.5xlO~5 Model results

Fort Dix, Burlington

County.

Winslow Township, Camden

County.

Lakewood, Ocean County

Brick Township, Ocean

County.

Northern Coastal Plain

New Jersey.

Nichols (1977a, p. 58).

Farlekas and others (1976, p.

133).

Nichols (1977a, p. 58).

Nichols (1977b, p. 48).

Nichols (1977a, p. 76).

NAVESINK-HORNERSTOWN CONFINING UNIT (C5)

Navesink Formation

Nave sink Formation

Navesink Formation

Red Bank Sand

Hornerstown Sand

Hornerstown Sand

Hornerstown Sand

Navesink Formation and

Hornerstown Sand.

2 Laboratory

test.

5.0xl(T4 to Laboratory

1.3X1CT1 test.

9 Laboratory

test.

l.SxlO" 1 Laboratory

test.

3.0xlO~3 and Laboratory

2.0xl(T2 test.

8.0xlO~2 to Laboratory

6.7X1CT 1 test.

4 Laboratory

test.

5.6xlO~2 Aquifer test

Arneytown, Burlington

County.

Winslow Township, Camden

County.

Sewell, Gloucester County

Arneytown, Burlington

County.

Arneytown, Burlington

County.

Winslow Township, Camden

County.

Sewell, Gloucester County

Salem, Salem County

Rush (1968, p. 51).

Farlekes and others (1976, p.

133).

Rosenau and others (1969, p.

46).

Rush (1968, p. 51).

Rush (1968, p. 52).

Farlekas and others (1976, p.

133).

Rosenau and others (1969, p.

46).

Rosenau and others (1969, p.

46).

BASAL KIRKWOOD CONFINING UNIT (C7)

Alloway Clay Member of

the Kirkwood Formation.

2.0xl(T5 to Laboratory

5.2xl(T5 tests.

Cumberland County Nemickas and Carswell (1976,

p. 4).
CONCEPTUAL HYDROGEOLOGIC MODEL H29

CONFINING UNIT BETWEEN THE LOWER AND MIDDLE 

POTOMAC-RARITAN-MAGOTHY AQUIFERS

The confining unit above the lower aquifer of the 

Potomac-Raritan-Magothy aquifer system is a section of 

predominantly silt and clay sediments, with some sand, 

in the lower third of the undifferentiated PotomacRaritan-Magothy aquifer system. In the model, this 

confining unit is referred to as the confining unit between 

the lower and middle Potomac-Raritan-Magothy aquifers 

and is designated as model unit Cl. The thickness of this 

confining unit is shown in figure 4. Confining-unit thickness data near the Delaware River in northwestern 

Salem, Gloucester, and Camden Counties, are from 

Zapecza (1984, pi. 6). In downdip areas in the eastern 

Coastal Plain, the confining-unit thickness is estimated 

from available borehole geophysical logs. The thickness 

of this confining unit ranges from less than 50 feet near 

the Delaware River to 500 feet in downdip areas near the 

Delaware River in Salem County. The modeled confining 

unit has the same areal extent as the lower PotomacRaritan-Magothy aquifer (Al) and is overlain everywhere by the middle Potomac-Raritan-Magothy aquifer 

(A2).

No previous estimates of vertical hydraulic conductivity have been made for the confining-unit sediments 

between the lower and middle aquifers of the PotomacRaritan-Magothy aquifer system in the New Jersey 

Coastal Plain. Many previous studies (Barksdale and 

others, 1958; Farlekas and others, 1976; Luzier, 1980; 

and Walker, 1983) have discussed various aspects of the 

hydrogeology of the lower aquifer of Potomac-RaritanMagothy aquifer system in combination with the middle 

or middle and upper aquifers of the Potomac-RaritanMagothy aquifer system. These studies suggest that the 

vertical hydraulic connection within the PotomacRaritan-Magothy aquifer system is relatively high and 

that the hydraulic conductivity of the confining unit 

between the lower and middle aquifers of the PotomacRaritan-Magothy aquifer system is somewhat higher 

than the hydraulic conductivity of the MerchantvilleWoodbury confining unit that overlies the upper aquifer 

of the Potomac-Raritan-Magothy aquifer system. However, similarity in water levels in the lower and middle 

parts of the aquifer system compared to the upper part of 

the aquifer system may result from the distribution of 

ground-water withdrawals rather than from the degree 

of hydraulic connection.

The hydraulic conductivity of the confining unit 

between the lower and middle Potomac-RaritanMagothy aquifers is assumed to be similar to (and 

possibly higher than) hydraulic conductivity estimates 

for the confining unit between the middle and upper 

Potomac-Raritan-Magothy aquifers and as much as two

orders of magnitude more than the hydraulic conductivity of the Merchantville-Woodbury confining unit.

MIDDLE POTOMAC-RARITAN-MAGOTHY AQUIFER

The middle Potomac-Raritan-Magothy aquifer completely overlies the confining unit between the lower and 

middle Potomac-Raritan-Magothy aquifers. In areas 

where the underlying aquifer and confining unit, model 

units Al and Cl, do not exist, the middle aquifer overlies 

bedrock, weathered bedrock, or clays. The modeled 

aquifer, model unit A2, represents the middle aquifer of 

the Potomac-Raritan-Magothy aquifer system, which is 

equivalent to the Farrington aquifer (the Farrington 

Sand Member of the Raritan Formation) in the northeastern New Jersey Coastal Plain.

Structure contours of the top of the middle PotomacRaritan-Magothy aquifer are shown in figure 5. The 

altitude on the top of the middle aquifer ranges from land 

surface in the outcrop area near the Fall Line to more 

than an estimated 2,800 feet below sea level in downdip 

seaward areas east of Atlantic County. The altitude data 

of the top of the aquifer near the Delaware River and in 

northwestern Monmouth and Ocean Counties are from 

Zapecza (1984, pi. 7). The top of the middle aquifer in 

downdip undifferentiated areas in the southern and 

southwestern Coastal Plain is estimated from available 

borehole geophysical logs. Generally, this aquifer is the 

sandiest part of the middle third of the undifferentiated 

Potomac-Raritan-Magothy aquifer system. The middle 

aquifer extends from the Fall Line to some unknown 

distance downdip beneath the Atlantic Ocean. However, 

the modeled freshwater part of the middle aquifer is 

shown to extend from the Fall Line to southern Cumberland and southern Atlantic and Ocean Counties but 

not beneath most of Cape May County. The thickness of 

the middle aquifer near the Delaware River ranges from 

50 feet to 150 feet and is more than 600 feet in downdip 

areas offshore of Ocean County.

The middle Potomac-Raritan-Magothy aquifer is continuous into Delaware where it is the sandy part of the 

upper half of the Potomac Formation (D.A. Vroblesky, 

written commun., 1985). The middle aquifer is equivalent 

to the Lloyd aquifer (the Lloyd Sand Member of the 

Raritan Formation) on Long Island, N. Y. (Henry Trapp, 

written commun., 1985).

Aquifer-test analyses (table 3) indicate that the transmissivity of the middle aquifer ranges from 550 to 22,000 

ft2/d; however, one aquifer test in Burlington County 

(Rush, 1968, p. 33) shows unrealistic transmissivity 

values over 68,000 ft2/d. Most of the aquifer-test analyses 

are from the northern Coastal Plain and give transmissivity values that are higher than the few analyses for 

the lower aquifer. Storage coefficient estimates from
H30 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

these tests range from 3.7xlO~5 to 8.1xlO~3 and are 

similar to storage coefficient estimates for the lower 

aquifer.

CONFINING UNIT BETWEEN THE MIDDLE AND UPPER 

POTOMAC-RARITAN-MAGOTHY AQUIFERS

The confining unit between the middle and upper 

Potomac-Raritan-Magothy aquifers is designated C2 in 

the model. This confining unit generally represents the 

clayey part within the middle third of the undifferentiated Potomac-Raritan-Magothy aquifer system and 

overlies the middle aquifer everywhere except where the 

middle aquifer crops out near the Fall Line. The thickness of the middle confining unit is shown in figure 6. 

Near the Fall Line, the thickness is generally less than 

50 feet (Zapecza, 1984, pi. 9). In downdip areas, the 

thickness was estimated on the basis of available geophysical logs. The confining unit generally thickens 

downdip and is more than 600 feet near the 10,000 mg/L 

chloride line.

Estimates of vertical hydraulic conductivity for the 

confining unit range from 8.6x 10~6 to 8.4x 10~2 feet per 

day (ft/d) (table 4). These estimates are derived from a 

flow modeling study of the underlying aquifer in the 

northeastern Coastal Plain by Farlekas (1979) and suggest that the vertical hydraulic conductivity varies several orders of magnitude locally.

UPPER POTOMAC-RARITAN-MAGOTHY AQUIFER

The upper Potomac-Raritan-Magothy aquifer overlies 

the confining unit between the middle and upper aquifers 

everywhere except where the confining unit crops out 

near the Fall Line. This aquifer, designated A3 in the 

model, is the upper aquifer of the Potomac-RaritanMagothy aquifer as described by Zapecza (1984, p. 18-19) 

and is primarily the Magothy Formation in New Jersey 

but is the Old Bridge aquifer (the Old Bridge Sand 

Member of the Magothy Formation) in the northeastern 

New Jersey Coastal Plain. The upper aquifer, like the 

middle aquifer, extends from its outcrop area near the 

Fall Line to some unknown distance downdip beneath 

the Atlantic Ocean. The downdip area of the upper 

aquifer simulated by the model, however, is limited to 

the area with freshwater. The modeled extent of the 

upper aquifer is greater than that of the lower and 

middle aquifers, because freshwater occurs offshore in 

the upper aquifer. The upper aquifer is present in each 

county of the New Jersey Coastal Plain.

The altitude of the top of the aquifer (fig. 7) ranges 

from land surface in the outcrop area to more than 2,200 

feet below sea level in downdip areas south of Cape May 

County. The altitude of the top of the upper aquifer is 

that shown by Zapecza (1984, pi. 10). The altitude in

offshore areas where no borehole geophysical logs are 

available was estimated on the basis of the onshore 

structural trends. The thickness of the upper aquifer of 

the Potomac-Raritan-Magothy aquifer system is shown 

by Zapecza (1984, p. 11). The aquifer is thinnest near the 

outcrop area, where it is less than 50 feet thick and near 

the Delaware Bay where it is about 75 feet thick. The 

aquifer thickens to more than 200 feet in eastern Monmouth County.

The upper aquifer is continuous with the Magothy 

Formation of Delaware (D.A. Vroblesky, written commun., 1985) and is modeled in the northern Atlantic 

Coastal Plain RASA study as the approximate lower 

third of the Magothy Formation in New York (P.P. 

Leahy, written commun., 1985). Except in the outcrop 

area, the upper aquifer is overlain everywhere by the 

Merchantville-Woodbury confining unit.

Two aquifer tests in New Jersey are summarized in 

table 3 for the upper aquifer. Although these tests are 

listed for the upper aquifer, this cannot be confirmed 

because of incomplete well records. There is no evidence 

to suggest that the hydraulic conductivity or lithology of 

the upper aquifer of the Potomac-Raritan-Magothy aquifer system differs greatly from the hydraulic conductivity and lithology of the lower or middle aquifers of the 

Potomac-Raritan-Magothy aquifer system. Differences 

in transmissivity among the three aquifers result primarily from differences in thickness.

MERCHANTVILLE-WOODBURY CONFINING UNIT

The Merchantville-Woodbury confining unit generally 

represents the sediments of the MerchantvilleWoodbury confining unit described by Zapecza (1984, p. 

19-20). However, several modifications were made to 

incorporate the unit into the model framework as model 

unit C3. In areas where the overlying Englishtown 

Formation includes an upper and lower sand unit within 

the aquifer (Nichols, 1977b, p. 15), the confining unit 

between these sands is specified for this report to be part 

of the Merchantville-Woodbury confining unit. The 

thickness of model unit C3 (fig. 8) is, therefore, slightly 

greater than the thickness of the MerchantvilleWoodbury confining unit shown by Zapecza (1984, pi. 12) 

in Ocean, southeastern Monmouth, and southeastern 

Burlington Counties. Also, in areas southeast of the 

downdip limit of the Englishtown aquifer system, 

Zapecza (1984, p. 19) includes all sediments between the 

overlying Wenonah-Mount Laurel aquifer and the underlying Potomac-Raritan-Magothy aquifer system in the 

Merchantville-Woodbury confining unit. Model unit C3, 

however, includes only the lower part of these sediments 

in these areas. The upper part is assigned to model unit 

C4. The thickness of the confining unit in Cumberland,
CONCEPTUAL HYDROGEOLOGIC MODEL H31

Cape May, Atlantic, and southern Burlington and Ocean 

Counties is, therefore, less than that shown by Zapecza 

(1984, pi. 12). The sediments represented by model unit 

C3 are illustrated in figure 2 and table 2. The modeled 

confining unit increases in thickness downdip, from less 

than 50 feet at the outcrop to more than 400 feet along 

the coast of Ocean County.

Estimates of vertical hydraulic conductivity for sediments of the Merchantville-Woodbury confining unit 

have been made from model simulation studies and 

laboratory analyses (table 4). Estimates range from 

8.6xlO~7 to 3.0xlO"2 ft/d. Luzier (1980, p. 29) shows 

hydraulic conductivity decreasing in the downdip direction. The sediments of the Merchantville-Woodbury confining unit have long been recognized (Barksdale and 

others, 1958, p. 135-136) as one of the most effective 

confining units in the New Jersey Coastal Plain.

ENGLISHTOWN AQUIFER

The Englishtown aquifer, designated A4 in the model, 

overlies the Merchantville-Woodbury confining unit but 

has a more limited areal extent. Model unit A4 represents both sand units of the Englishtown aquifer system 

described by Zapecza (1984, p. 20-22). The altitude of the 

top of the Englishtown aquifer is shown on figure 9. The 

aquifer extends from its outcrop area several miles 

southeast of the Fall Line to northern Cumberland, 

northern Atlantic, southern Burlington, and southern 

Ocean Counties. The downdip limit of this model unit is 

at a facies change to silt and clay and is the downdip limit 

of the permeable sand. The Englishtown aquifer contains 

freshwater everywhere. The altitude of the top of the 

aquifer ranges from land surface in the outcrop area to 

more than 1,600 feet below sea level offshore of Ocean 

County. The altitudes shown in figure 9 are those shown 

by Zapecza (1984, pi. 13), with projected altitudes in 

offshore areas.

The thickness of the modeled aquifer is the same as the 

thickness of the Englishtown aquifer system shown by 

Zapecza (1984, pi. 14). The aquifer is generally less than 

100 feet thick. However, the Englishtown aquifer has its 

greatest thickness of 200 feet in southern Monmouth and 

northeastern Ocean Counties, where two distinct permeable sand units are present. The thickness of the upper 

sand unit, which has the greatest withdrawals, is less 

than 120 feet in this area.

The Englishtown aquifer in New Jersey is continuous 

with the Englishtown Formation in Delaware (D.A. 

Vroblesky, written commun., 1985) and is modeled as the 

approximate middle third of the Magothy Formation in 

New York in the hydrogeologic framework of the northern Atlantic Coastal Plain RASA model (P.P. Leahy, 

written commun., 1985). The Englishtown aquifer is

overlain everywhere except in its outcrop area by the 

Marshalltown-Wenonah confining unit.

Transmissivity estimates for the Englishtown aquifer 

derived from model simulations range from 400 to 2,400 

ft2/d (table 3). Transmissivity estimates from aquifertest analyses are comparable and range from 1,100 to 

2,100 ft2/d. These estimates are considerably lower than 

transmissivity estimates for the Potomac-RaritanMagothy aquifers. These lower transmissivities are 

related to the low hydraulic conductivity and thickness of 

the Englishtown aquifer. Estimates of the storage coefficient range from 7.6xlO"5 to 2.7xlO"4 (table 3).

MARSHALLTOWN-WENONAH CONFINING UNIT

In areas overlying the Englishtown aquifer, the 

Marshalltown-Wenonah confining unit represents the 

sediments of the Marshalltown-Wenonah confining unit 

described by Zapecza (1984, p. 22-23). In areas southeast 

of the downdip extent of the Englishtown aquifer, this 

unit is part of the Merchantville-Woodbury confining unit 

described by Zapecza (1984, p. 19-20). The sediments 

represented by model unit C4 are shown in table 2 and 

figure 2. This confining unit is relatively thin, ranging 

from less than 20 feet to less than 100 feet, and has the 

same downdip extent as the Merchantville-Woodbury 

confining unit (C3) (fig. 10). Therefore, southeast of the 

downdip limit of the Englishtown aquifer (A4), this 

confining unit directly overlies the MerchantvilleWoodbury confining unit (C3).

Estimates of vertical hydraulic conductivity for sediments of the Marshalltown-Wenonah confining unit 

range from about 5.7xlO"6 to 4.9xlO"4 ft/d (table 4). 

However, one laboratory analysis of cores from Camden 

County indicated an unusually high vertical hydraulic 

conductivity of 1.3 xlO" 1 ft/d.

WENONAH-MOUNT LAUREL AQUIFER

The Wenonah-Mount Laurel aquifer, designated A5 in 

the model, overlies the Marshalltown-Wenonah confining 

unit (C4). The altitude data of the top of the WenonahMount Laurel aquifer (fig. 11) is from Zapecza (1984, pi. 

16). The aquifer extends from its outcrop area, several 

miles southeast of the Fall Line, about 50 to 60 miles 

downdip, where there is a facies change from sand to silt 

and clay. The altitude of the top of the aquifer ranges 

from land surface in its outcrop area and is estimated to 

be more than 2,400 feet below sea level beneath the 

Atlantic Ocean. The aquifer is thickest in southeastern 

Gloucester and Salem Counties and northwestern Cumberland County where it is over 120 feet thick (Zapecza, 

1984, pi. 17). The aquifer generally thins downdip and is 

less than 40 feet thick in southern Cape May County.
H32 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

The Wenonah-Mount Laurel aquifer is equivalent to 

permeable sands in the Monmouth Formation in Delaware (D.A. Vroblesky, written commun., 1985) and is 

modeled as the upper part of the Magothy Formation in 

New York by the regional RASA study (P.P. Leahy, 

written commun., 1985).

Estimates of transmissivity from aquifer tests and 

model simulations range from 360 to 1,430 ft2/d (table 3). 

Storage coefficients were estimated to be from 

1.5xlO"5to 3.5xlO~4 (table 3). The hydraulic characteristics of the Wenonah-Mount Laurel aquifer are similar 

to those of the Englishtown aquifer.

NAVESINK-HORNERSTOWN CONFINING UNIT

The Navesink-Hornerstown confining unit, designated 

C5 in the model, overlies the Wenonah-Mount Laurel 

aquifer (A5) everywhere except in the aquifer's outcrop 

area. Model unit C5 represents the lower part of the 

composite confining unit described by Zapecza (1984, 

p. 24-25). The unit includes the Navesink Formation, 

Red Bank Sand, Tinton Sand, and the Hornerstown 

Sand. These minor aquifers are relatively thin and 

limited in their areal extent.

Thickness of the Navesink-Hornerstown confining unit 

is shown in figure 12. Throughout most of the New 

Jersey Coastal Plain, the confining unit is less than 80 

feet thick. However, in central Monmouth County, the 

unit is 100 to 180 feet thick because of the presence of the 

Red Bank and Tinton Sands.

Estimates of vertical hydraulic conductivity for sediments within the Navesink-Hornerstown confining unit 

range from 5.0xlO"4 to 9 ft/d (table 4). Many of the 

estimates are several orders of magnitude higher than 

for sediments in other confining units. Generally, these 

relatively high vertical hydraulic conductivities are for 

minor sand layers within the confining unit and are not 

representative of the confining unit's overall vertical 

hydraulic conductivity.

VINCENTOWN AQUIFER

The Vincentown Formation overlies the NavesinkHornerstown confining unit. However, throughout most 

of its extent the formation is a confining unit (Zapecza, 

1984, p. 25). The Vincentown Formation is an aquifer in 

its outcrop area and for about 8 to 10 miles downdip. The 

aquifer part of the Vincentown Formation is designated 

A6 in the model and appears in Salem, Gloucester, 

Camden, Burlington, Ocean, and Monmouth Counties 

(fig. 13). The aquifer is not present in New York. In 

Delaware, the Vincentown aquifer consists of permeable 

sands in the Rancocas Group (D.A. Vroblesky, written 

commun., 1985).

The altitude of the top of the aquifer is shown in figure 

13 and is the same as that shown by Zapecza (1984, pi. 

19). The altitude of the top of the aquifer ranges from 

altitudes of more than 100 feet above sea level in the 

outcrop to more than 200 feet below sea level downdip in 

Salem County. The thickness of the Vincentown aquifer 

is shown by Zapecza (1984, pi. 19). Generally, the aquifer 

is less than 100 feet thick. However, thicknesses of 140 

feet occur in central Monmouth County.

Only one estimate of transmissivity is available for the 

Vincentown aquifer. A laboratory analysis of sediments 

from Burlington County resulted in an estimated transmissivity of 530 ft2/d (table 3).

VINCENTOWN-MANASQUAN CONFINING UNIT

The Vincentown aquifer is overlain everywhere, 

except in the outcrop area, by the Manasquan Formation. The Manasquan-Vincentown confining unit, designated C6 in the model, includes the downdip silt and clay 

portions of the Vincentown Formation, the Manasquan 

Formation, and, locally, the overlying Shark River Formation. These sediments are part of the composite 

confining unit described by Zapecza (1984, p. 24-25).

The thickness of the Vincentown-Manasquan confining 

unit, shown in figure 14, ranges from about 50 feet at the 

outcrop area to about 1,000 feet in southern Cape May 

County. This unit has the same downdip extent as the 

Navesink-Hornerstown confining unit (C5). Therefore, 

in areas southeast of the downdip extent of the underlying Vincentown aquifer (A6), the VincentownManasquan confining unit (C6) directly overlies the 

Navesink-Hornerstown confining unit (C5). This relation 

is shown in figure 2 and table 2. No estimates of vertical 

hydraulic conductivity are available for the VincentownManasquan confining unit.

PINEY POINT AQUIFER

The Piney Point aquifer described by Zapecza (1984, 

p. 26-29) is designated as model unit A7. The altitude of 

the top of the Piney Point aquifer is shown in figure 15. 

The aquifer does not crop out because it is overlain 

entirely by the basal clay of the Kirkwood Formation. 

The updip limit of the Piney Point aquifer is generally at 

the downdip limit of the Vincentown aquifer (A6) (figs. 2, 

13, and 15). The Piney Point aquifer probably thins and 

is not present several miles downdip of the Atlantic 

Coast. The altitude of the top of the aquifer is the same 

as that shown by Zapecza (1984, pi. 20), with altitudes 

beneath the ocean estimated from onshore contour 

trends and available offshore data. The altitude of the top 

of the aquifer ranges from about 50 feet below sea level 

in southeastern Salem and Gloucester Counties to about
CONCEPTUAL HYDROGEOLOGIC MODEL H33

1,300 feet below sea level beneath the Atlantic Ocean 

southeast of Atlantic County.

The thickness of the Piney Point aquifer is shown by 

Zapecza (1984, pi. 21). The aquifer is thickest in western 

Cumberland County where it is over 200 feet thick. The 

aquifer thins to the northeast where it is less than 40 feet 

thick in Atlantic County but thickens again to over 120 

feet in Burlington and Ocean Counties. The Piney Point 

aquifer is not present in New York but is continuous into 

Delaware (D.A. Vroblesky, written commun., 1985). 

The only estimate of transmissivity of the Piney Point 

aquifer in New Jersey based on aquifer-test data is 1,400 

ft2/d. Estimates of transmissivity and storage coefficient 

for the aquifer in Delaware are shown in table 3.

BASAL KIRKWOOD CONFINING UNIT

The basal Kirkwood confining unit, designated C7 in 

the model, represents the basal clay of the Kirkwood 

Formation and, locally, silty parts of the Piney Point 

Formation. These sediments are the uppermost part of 

the composite confining unit described by Zapecza (1984, 

p. 24-25). The confining unit completely overlies the 

Piney Point aquifer (A7) and extends several miles 

northwest of the aquifer's updip limit. Northwest of the 

Piney Point aquifer the basal Kirkwood confining unit 

overlies the Vincentown-Manasquan confining unit (C6).

Thickness of the basal Kirkwood confining unit is 

shown in figure 16. Generally, the unit thickens downdip. 

The unit is over 140 feet thick in southern Cape May 

County, but its greatest thickness exceeds 160 feet in 

eastern Ocean County and just offshore.

Only one estimate of vertical hydraulic conductivity is 

available for sediments of the basal Kirkwood confining 

unit. A laboratory analysis of the Alloway Clay Member 

of the Kirkwood Formation, part of the confining unit, 

indicated a vertical hydraulic conductivity ranging from 

2.0xlO~5 to 5.2xlO~5 ft/d (table 4).

LOWER KIRKWOOD-COHANSEY AQUIFER AND CONFINED 

KIRKWOOD AQUIFER

The lower Kirkwood-Cohansey aquifer and the confined Kirkwood aquifer are designated as A8 in the 

model. In downdip areas, the modeled aquifer represents 

the Atlantic City 800-foot sand and the overlying, relatively minor, Rio Grande water-bearing zone. In this 

report, the Atlantic City 800-foot sand and the Rio 

Grande water-bearing zone are together referred to as 

the confined Kirkwood aquifer. In updip areas, the 

modeled aquifer represents the lower part of the unconfined Kirkwood-Cohansey aquifer system. The Atlantic 

City 800-foot sand and the Kirkwood-Cohansey aquifer 

system are described and mapped by Zapecza (1984, p. 

29-34, pis. 22, 23, and 24), but Zapecza does not subdivide the Kirkwood-Cohansey aquifer system into an 

upper and lower part. He also describes, but does not 

map, the Rio Grande water-bearing zone (Zapecza, 1984, 

p. 31-32). The relation between the hydrogeologic units 

and the modeled aquifer are shown in figure 2 and 

table 2.

The Kirkwood-Cohansey aquifer system was subdivided in this study into an upper and lower aquifer in 

updip areas to better represent the vertical head distribution in the unconfined aquifer system and to provide a 

lateral connection between the confined Kirkwood aquifer and the lower Kirkwood-Cohansey aquifer. Zapecza 

(1984, p. 29) states that the Atlantic City 800-foot sand 

has not been mapped beyond its overlying confining unit, 

and its connection with the unconfined aquifer is not 

known.

The altitude of the top of the modeled aquifer and the 

approximate extent of the confined Kirkwood aquifer are 

shown in figure 17. The updip limit of the confined 

Kirkwood aquifer extends through southeastern Cumberland, central Atlantic, southeastern Burlington, and 

southern Ocean Counties and is the same as the limit of 

the overlying confining unit. This line divides the modeled aquifer into the lower part of the unconfined aquifer 

in updip areas to the northwest and a confined aquifer in 

downdip areas to the southeast. Southeast of this line the 

altitude of the top of the modeled aquifer is the top of the 

Rio Grande water-bearing zone. In this area, the altitude 

of the top is 50 to 250 feet above the top of the Atlantic 

City 800-foot sand shown by Zapecza (1984, pi. 22). 

Northeast of this line the top of the modeled aquifer 

continues to rise until it reaches the water table. The 

altitude of the top of the modeled aquifer (fig. 17) ranges 

from the water table in its outcrop area, several miles 

southeast of the Fall Line, to 500 feet below sea level in 

southern Cape May County and is estimated to be more 

than 1,100 feet below sea level at the southeast model 

boundary.

The thickness of the modeled aquifer ranges from 

about 50 feet in its outcrop area to about 200 feet in Cape 

May County. The lower Kirkwood-Cohansey aquifer is 

the updip part of the aquifer and is approximately the 

lower third of the Kirkwood-Cohansey aquifer system 

described by Zapecza (1984, p. 32-34). The thickness of 

the confined Kirkwood aquifer, which is the downdip 

part of the modeled aquifer, is the combined thickness of 

the Atlantic City 800-foot sand, the Rio Grande waterbearing zone, and the intervening confining unit.

The confined Kirkwood aquifer extends to the southeast model boundary. However, the aquifer probably 

contains freshwater for at least 25 miles offshore beyond 

the model boundary. The unit thins toward the northeast 

and is not present in Long Island, N.Y. (Henry Trapp, 

written commun., 1985). To the southwest, the confining
H34 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

units within the modeled aquifer become thicker, and the 

aquifer includes the Frederica and Cheswold aquifers in 

Delaware (D.A. Vroblesky, written commun., 1985).

Estimates of transmissivity of the modeled aquifer 

from Atlantic, Cape May, and Ocean Counties range 

from 1,500 to 12,500 ft2/d (table 3). Storage coefficient 

estimates range from 8.5xlO~5 to 6.0xlO~4 . Transmissivity estimates for the lower Kirkwood-Cohansey aquifer and confined Kirkwood aquifer (A8) are lower than 

transmissivity estimates for the three Potomac-RaritanMagothy aquifers (Al, A2, and A3) but are slightly 

higher than estimates for the other underlying aquifers 

(A4-A7).

CONFINING UNIT OVERLYING THE RIO GRANDE 

WATER-BEARING ZONE

Model unit C8 represents the confining unit overlying 

the Rio Grande water-bearing zone and is designated as 

C8 in the model. This confining unit is the upper part of 

the confining unit overlying the Atlantic City 800-foot 

sand described by Zapecza (1984, p. 31). The confining 

unit completely overlies the confined Kirkwood aquifer, 

does not crop out, and is present mainly in southern 

Ocean, southeastern Atlantic, and Cape May Counties 

(fig. 18).

The thickness of the confining unit is shown in figure 

18. The unit thickens downdip, ranging from 50 feet near 

its updip limit to 200 feet in southern Cape May County. 

The unit is 100 to 200 feet thinner than the confining unit 

mapped by Zapecza (1984, pi. 22) because he includes the 

thickness of the Rio Grande water-bearing zone and the 

confining unit underlying this zone. No estimates of 

vertical hydraulic conductivity are available.

UPPER KIRKWOOD-COHANSEY AQUIFER

The sediments in the upper part of the unconfined 

Kirkwood-Cohansey aquifer system are designated as 

model unit A9 and are referred to in the model as the 

upper Kirkwood-Cohansey aquifer. This modeled aquifer 

directly overlies the lower Kirkwood-Cohansey aquifer 

(updip part of A8) in areas northwest of the updip limit of 

the confined Kirkwood aquifer. Southeast of the limit, 

the upper Kirkwood-Cohansey aquifer represents unconfined and confined sediments of the Kirkwood Formation 

above the confining unit overlying the Rio Grande waterbearing zone (C8). Throughout most of its onshore 

extent, the modeled aquifer is unconfined; however, in 

the peninsular part of Cape May County and offshore the 

aquifer is confined by the overlying estuarine clay facies 

of the Cape May Formation (Gill, 1962a, fig. 2).

The altitude of the top of the confined part of the upper 

Kirkwood-Cohansey aquifer is shown in figure 19. 

Although the top of the sediments is the altitude of land

surface, the altitude of the top of the saturated sediments 

(water table) is estimated to be at or near land surface 

near streams and surface-water bodies and up to several 

tens of feet below land surface near local ground-water 

divides. The altitude of the top of the confined part of the 

upper Kirkwood-Cohansey aquifer in Cape May County 

is similar to that shown by Gill (1962a, fig. 6) for the top 

of the estuarine sand facies. The altitude of the top of the 

aquifer in offshore areas is the ocean and bay bottoms. 

The thickness of the unconfined Kirkwood-Cohansey 

aquifer system, which includes the unconfined parts of 

the lower Kirkwood-Cohansey aquifer (updip part of A8) 

and the upper Kirkwood-Cohansey aquifer (A9), is 

described and shown by Zapecza (1984, pi. 24 and p. 

32-34). The confined part of the upper KirkwoodCohansey aquifer is from 150 to 250 feet thick in Cape 

May County. Estimates of transmissivity for the upper 

Kirkwood-Cohansey aquifer from aquifer-test analyses 

range from 3,600 to 20,000 ft2/d (table 3). The higher 

estimates are generally for the thicker parts of the 

unconfined part of the aquifer. Estimates of storage 

coefficient from these tests range from 1.2xlO~4 to 

4.4X10"2 .

ESTUARINE CLAY CONFINING UNIT

The estuarine clay confining unit, designated C9 in the 

model, represents the estuarine clay facies described by 

Gill (1962a, p. 25-26). Onshore, this confining unit is 

present only in the peninsular part of Cape May County 

where the upper Kirkwood-Cohansey aquifer (A9) is 

confined. Offshore, the estuarine clay confining unit 

extends beneath Delaware Bay and the Atlantic Ocean.

The thickness of the estuarine clay confining unit is 

shown in figure 20. The unit has a fairly uniform thickness of about 50 feet, although locally in southern Cape 

May County the unit is over 100 feet thick. However, 

contours in offshore areas are highly approximate. There 

are no estimates of vertical hydraulic conductivity for 

this confining unit.

HOLLY BEACH AQUIFER

The Holly Beach aquifer, designated A10 in the model, 

represents part of the unconfined Holly Beach waterbearing zone described by Gill (1962a, p. 41). The modeled aquifer is the Holly Beach water-bearing zone only 

on the peninsular part of Cape May County where it is 

underlain by the estuarine clay facies of the Cape May 

Formation mapped by Gill (1962a, fig. 8). In the northern 

part of the county where the clay facies is absent, 

sediments of the Holly Beach water-bearing zone are 

combined with the upper Kirkwood-Cohansey aquifer 

(A9). The lithology and stratigraphy of the sediments 

comprising this aquifer are discussed in detail by Gill
CONCEPTUAL HYDROGEOLOGIC MODEL H35

(1962a, p. 21-32). The aquifer does not extend offshore 

and is not continuous into Delaware.

The altitude of the top of the sediments comprising the 

Holly Beach aquifer is at land surface, which ranges from 

about 25 feet above sea level in the central Cape May 

Peninsula to sea level along the shore. These sediments 

are about 30 to 80 feet thick. However, the thickness and 

altitude of the top of the aquifer are generally taken to 

refer only to the saturated sediments. Therefore, based 

on subtracting the altitude of the top of the estuarine clay 

facies of the Cape May Formation (Gill, 1962a, fig. 7) 

from the water table (Gill, 1962a, fig. 46), the altitude of 

the saturated sediments ranges from about 15 feet above 

sea level to near sea level and the thickness ranges from 

30 to 70 feet. No estimates of transmissivity or of the 

storage coefficient of this unit have been made.

GROUND-WATER FLOW SYSTEM

The ground-water flow system is defined by the flow 

patterns and rates within the aquifers. The Coastal Plain 

flow system is dynamic and has changed greatly from 

prepumping conditions. Movement of ground water in 

the modeled area under prepumping conditions was 

controlled by several factors: (1) hydraulic properties of 

the saturated sediments, (2) topography, and (3) 

recharge and discharge to and from the aquifers at the 

model boundaries. After pumping began, ground-water 

flow was affected by the location and amount of withdrawals. Other factors affecting ground-water flow, such 

as seasonal or yearly changes in areal recharge or 

changes in recharge caused by changes in land use, are 

considered short-term effects; therefore, they are not 

discussed in this report.

Coastal Plain aquifers generally transmit water easily 

compared to confining units, which transmit water only 

slightly. Flow within the aquifers is predominantly horizontal, although some vertical flow exists. Confining 

units generally have very large vertical hydraulic gradients, and flow is mostly vertical.

Topography has a major effect on the prepumping flow 

system within the Coastal Plain aquifers because it 

influences regional hydraulic gradients and the location 

of recharge and discharge areas. The prepumping 

regional flow system had ground-water recharge in areas 

of high water levels corresponding to high land altitudes, 

primarily in northwestern Monmouth County near the 

Fall Line and the aquifers' outcrop areas, in western 

Ocean County, and in central Gloucester and Camden 

Counties. Discharge areas in the prepumping regional 

flow system included the Atlantic Ocean, the Delaware 

River, the Delaware and Raritan Bays, and large rivers 

in the Coastal Plain.

Recharge to the confined aquifers during prepumping 

conditions generally flowed vertically downward through 

confining units and laterally downdip within aquifers and 

then upward through confining units to be discharged at 

large surface-water bodies. Figure 21 shows generalized 

flow patterns in four aquifers. These flow patterns are 

based on the prepumping potentiometric surface maps 

by Zapecza, Voronin, and Martin (1987, figs. 4, 5, 8, and 

10), which were derived from the earliest recorded 

water-level measurements. Flow in downdip areas in the 

three Potomac-Raritan-Magothy aquifers (Al, A2, and 

A3) was not only vertically upward but also lateral and 

updip. The outcrop area of the middle and upper 

Potomac-Raritan-Magothy aquifers along the Delaware 

River was a discharge area for this updip flow. The fairly 

tight Merchantville-Woodbury confining unit (C3) separates the regional flow system in the underlying 

Potomac-Raritan-Magothy aquifers from that in the 

overlying Englishtown aquifer (A4). In many aquifers, 

updip flow toward outcrop areas occurs locally from 

adjacent ground-water highs directly downdip of the 

outcrop areas. Prepumping flow patterns are more local, 

and flow is faster in the unconfined outcrop areas of the 

aquifers than in the deeper confined parts. The Piney 

Point aquifer (A7) is totally confined and has a regional 

flow system in contrast to numerous local flow systems in 

the unconfined lower and upper Kirkwood-Cohansey 

aquifers (A8 and A9) (fig. 21).

The major source of water to the aquifers is precipitation that percolates through the unsaturated zone to the 

saturated zone of the unconfined parts of the Coastal 

Plain aquifers. A large part of this ground-water 

recharge is discharged to nearby surface-water bodies. 

Only a small amount infiltrates through confining units to 

recharge the underlining confined aquifers. In the central and southeastern Coastal Plain, precipitation is 

about 45 inches per year (in/yr), and evapotranspiration 

is about 22.5 in/yr according to Rhodehamel (1970, p. 6 

and 7). He estimated total runoff for the same area to be 

about 22.5 in/yr with about 2.5 in/yr being surface or 

overland runoff and about 20 in/yr being ground-water 

runoff or ground-water discharge to streams. In Rhodehamel's budget, ground-water recharge is equivalent to 

ground-water runoff. Of the 20 in/yr of ground-water 

recharge, Rhodehamel estimated 3 in/yr to be deep flow 

to the confined aquifers. Therefore, most ground-water 

recharge, about 17 in/yr for this area, remains in the 

shallow unconfined aquifers.

Under prepumping conditions, deep flow to the confined aquifers was mainly discharged vertically upward 

through confining units to large surface-water bodies. 

Flow along the freshwater-saltwater boundary was generally upward discharge to the ocean. Most flow beneath 

the Delaware and Raritan Bays was upward discharge.
H36 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

PENNSYLVANIA

Upper Potomac-Raritan-Magothy aquifer 

(model layer A3)

Englishtown aquifer 

(model layer A4)

PENNSYLVANIA

.ELAWARF

I 

RARITAN

^ ,J\w-y wwit^/ ^i

r-> L ^.n^-. -^>f

\ MML-,f«V-^ . .< /

V

> 'viVA^

^ ^

OEL^WARd \ Y-

') DELAWARE 

\ BAY

Piney Point aquifer 

(model layer A7)

Lower and Upper Kirkwood-Cohansey aquifers 

(model layers A8 and A9)

10 20 MILES

EXPLANATION 

DIRECTION OF PREPUMPING GROUND-WATER FLOW

FIGURE 21. Generalized patterns of prepumping ground-water flow in four Coastal Plain aquifers.
SIMULATION OF GROUND-WATER FLOW H37

However, some ground-water flow in the deep confined 

aquifers beneath the bays was lateral as shown by Back 

(1966, p. A10).

Under pumping conditions, flow patterns changed in 

response to ground-water withdrawals. Water levels 

have declined in areas of ground-water withdrawals to 

create local and regional cones of depression in both 

confined and unconfined parts of the ground-water system. Several major cones of depression are shown in 

figure 22.

In the Potomac-Raritan-Magothy aquifer system there 

is a steep cone of depression in the middle aquifer (A2) 

near Raritan Bay in Middlesex and Monmouth Counties 

(fig. 22). On the basis of simulation, Farlekas (1979, p. 

51) concludes that vertical leakage from the Old Bridge 

(upper Potomac-Raritan-Magothy aquifer, A3) is the 

major source of water for the withdrawals in the Farrington (middle Potomac-Raritan-Magothy aquifer, A2) 

and that other sources included water from aquifer 

storage and recharge from the outcrop area of the 

Farrington aquifer. The most areally extensive cone of 

depression in New Jersey appears in the upper, middle, 

and lower Potomac-Raritan-Magothy aquifers (Al, A2, 

and A3) centered in northwest Camden County (Walker, 

1983, pis. 1 and 2). Luzier (1980, p. 68) states that near 

the city of Camden, the three stratigraphic units of the 

Potomac-Raritan-Magothy aquifer system function as 

one hydrologic system and that withdrawals had initially 

decreased discharge to the Delaware River and later 

(after 1960) induced recharge from the river.

In southern Monmouth and northeastern Ocean Counties, the Englishtown (A4) and Wenonah-Mount Laurel 

(A5) aquifers have very large and deep cones of depression (fig. 22) (Walker, 1983, pis. 3 and 4). Nichols (1977a, 

p. 96) on the basis of model simulation attributes both of 

these cones to withdrawals from the Englishtown aquifer 

and attributes the source of the water to vertical leakage 

from the aquifers above the Wenonah-Mount Laurel 

aquifer and lateral flow from the outcrop area of the 

Wenonah-Mount Laurel aquifer. In the confined Kirkwood aquifer (A8), a regional cone of depression centered 

in Atlantic County has developed that extends from the 

aquifer's updip limit to downdip areas beneath the Atlantic Ocean (Walker, 1983, pi. 5).

After prepumping conditions, lateral flow in the aquifers between Delaware and New Jersey and between 

New Jersey and Long Island changed in response to 

water- level declines. In most aquifers, flow toward New 

Jersey has increased or flow from New Jersey has 

reversed direction. However, in the Piney Point aquifer 

(AT), declining water levels in Delaware (Leahy, 1979, p. 

18) have increased flow from New Jersey toward Delaware. In the three Potomac-Raritan-Magothy aquifers 

(Al, A2, and A3), the confined Kirkwood aquifer (A8),

and the upper Kirkwood-Cohansey aquifer (A9), prepumping movement of water downdip toward the saltwater areas within the aquifers has decreased in 

response to ground-water withdrawals, and a corresponding increase in chloride concentrations in downdip 

areas is expected.

SIMULATION OF GROUND-WATER FLOW

DIGITAL MODEL

Heads in the 10 aquifers of the New Jersey Coastal 

Plain were simulated by using a multilayer finitedifference model. A modified version of the Trescott 

(1975) computer codes was used and is described by 

Leahy (1982). A schematic representation of the model 

units used to represent the hydrogeologic units (fig. 2 

and table 2) is shown in figure 23. A quasi-threedimensional representation of the aquifers and confining 

units was used, in which it is assumed that flow is 

entirely horizontal within the aquifers and vertical 

through the confining units. Water levels within the 

confining units were not simulated, but vertical flow 

through the confining units is calculated by using vertical 

leakance (hydraulic conductivity divided by thickness).

APPROACH

Water levels were simulated for transient pumping 

conditions from 1896 to 1981 and prepumping steadystate conditions. A series of three models was used to 

simulate the conceptualized steady-state and transient 

flow systems. A 10-layer steady-state model was used to 

obtain roughly calibrated aquifer and confining-unit 

characteristics and to quantify the amount of flow from 

the unconfined parts of the aquifers into underlying 

confined aquifers. An 11-layer steady-state model was 

used to calculate initial water level conditions for an 

11-layer transient model. The transient model was used 

to further calibrate aquifer and confining-unit properties. A flow chart showing the various stages of the 

modeling process discussed below is shown in figure 24.

The initial estimates of aquifer and confining-unit 

characteristics were used in a 10-layer steady-state 

model to simulate prepumping conditions. The 10-layer 

model has lateral no-flow boundaries in all of the aquifers. The upper boundary is a constant-head boundary 

representing the long-term average altitude of the water 

table in the outcrop areas of the aquifers. The 10-layer 

model was used to simulate only prepumping steadystate conditions, because simulating the water table as a 

constant-head boundary provides an infinite amount of 

recharge to the confined aquifers. A detailed discussion 

of the 10-layer model boundaries is necessary and is 

discussed in a later section on boundary conditions.
H38 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

75° 74° 75° ^^^ 74°

PENNSYLVANIA

\ I

Middle Potomac-Raritan-Magothy aquifer 

(model layer A2)

PENNSYLVANIA

 -i

. ELAWA1U: \

Englishtown aquifer 

(model layer A4)

PENNSYLVANIA

S-ELAWAKLl \

' \l

) DELAWARE 

BA\

0 10 20 MILES

I I I

0 10 20 KILOMETERS

EXPLANATION

 60 POTENTIOMETRIC CONTOUR Shows altitude 

at which water level would have stood in tightly cased wells. Dashed where approximately 

located. Contour interval 20 and 60 feet. 

National Geodetic Vertical Datum of 1929

Interpreted potentiometric contours modified from 

Walker (1983, pis. 1, 3, and 5) and are based on 

measurements from October to December 1978.

Confined Kirkwood aquifer 

(model layer A8)

FIGURE 22. Major cones of depression in three Coastal Plain aquifers, 1978.
SIMULATION OF GROUND-WATER FLOW H39

NW SE

| |

////

EXPLANATION

AQUIFER Numbers refer to model units 

listed in table 2

CONSTANT HEAD

CONFINING UNIT Numbers refer to 

model units listed in table 2

EFFECTIVE STREAM BED LEAKANCE

RECHARGE TO UNCONFINED AQUIFER 

NODE

FLUX BOUNDARY 

NO-FLOW BOUNDARY

VERTICAL HYDRAULIC CONNECTION 

BETWEEN CONFINING UNITS Aquifer 

is missing

A9

A10

ATLANTIC 

OCEAN

.V.CH--.:

A9

A8

A A A A -'

FALL LINE

:' CH-V

A6

A7

VV7

;CB;

A5

,C4

A4

I

A3

A2

A1

y////////////////////////////////////%

FIGURE 23. Schematic representation of aquifers, confining units, and boundary conditions in the digital flow model.

To simulate changes in the water table under pumping 

conditions, an 11-layer model was used. The constanthead boundary representing the water table was 

removed from the outcrop areas, and recharge was 

added to the unconfined outcrop areas. In all onshore 

nodes an overlying constant-head boundary representing 

streams was added. The recharge boundary at the water 

table allows the model to simulate declines in water-table 

altitudes under pumping conditions. The 11-layer model 

was used to simulate both prepumping steady-state 

conditions and transient conditions from 1896 to 1981. 

The simulated prepumping water levels from the 

11-layer model were used as initial conditions for transient simulations. Model input data that were changed 

during calibration were updated in the 10-layer and 

11-layer steady-state simulations and in the 11-layer 

transient simulations to ensure compatible results among 

the three models.

Both the 11-layer steady-state and transient models 

have lateral flow boundaries. The boundary flows were 

calculated by the regional RASA model (Leahy and 

Martin, 1986). The region?! RASA model simulates flow 

in the northern Atlantic Coastal Plain by using the 

approach and design similar to that used in the New 

Jersey subregional model. Model input data changes 

during calibration of the New Jersey flow model were 

updated in the New Jersey Coastal Plain area of the 

regional RASA model, and boundary flows were recalculated as needed to ensure compatible results between 

the regional and New Jersey subregional models. The

lateral boundaries and estimates of lateral flows are 

discussed in the later sections on boundary conditions 

and model input data.

GRID DESIGN

The modeled aquifers were discretized by using a 

finite-difference grid shown in figure 25. The model area 

was divided by using 29 rows and 51 columns. Nodes in 

columns 1 and 51 and rows 1, 28, and 29 were not active 

in the calibration simulation; however, nodes in row 28 

were used during some of the sensitivity simulations 

described later. The block-centered nodes are the center 

of the cell areas between two adjacent lines in the row 

direction (southwest to northeast) and two adjacent lines 

in the column direction (northwest to southeast). Nodes 

are designated in this report by row number followed by 

column number. For example, node 23, 18 is in row 23 

and column 18. About 57 percent of the 14,790 nodes used 

to simulate the 10 aquifers are active.

A variable grid spacing is used to minimize the number 

of nodes in areas where fine-scale definition is not 

necessary. Grid spacing is largest in Delaware and in 

areas with little data on water levels or aquifer characteristics. Cell areas are 6.25 mi2 in the northern and 

southwestern New Jersey Coastal Plain, 9.375 mi2 in the 

southeastern Coastal Plain, and as large as 47.5 mi2 in 

offshore areas.

The grid is aligned approximately parallel to the Fall 

Line and the strike of the Coastal Plain hydrogeologic 

units. The column direction of the New Jersey
H40 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

INITIAL DISCRETIZED

ESTIMATES OF 

HYDRAULIC PROPERTIES

MARYLAND-DELAWARE I 

I 11-LAYER TRANSIENT '

INSERT UPDATED 

_ DATA FROM__ _ 

SIMULATION [MARYLAND-DELAWARE 

WITH Wl I H FLUX FLUX BOUNDARY BOUNDARY i 1 MODEL

TRANSFER NEW JERSEY 

F SUBREGIONAL DATATO 

I REGIONAL MODEL

ID- REGIONAL

LAYER STEADY-STATE I 

MODEL I

 T. 

10-LAYER PREPUMPING 

STEADY-STATE 

SIMULATION

CALCUATE EFFECTIVE VERTICAL 

LEAKANCE BETWEEN 

STREAM AND WATER TABLES

11-

REGIONAL 

LAYER STEADY-STATE | 

SIMULATION I

I I CALULATE AND TRANSFER

1 ' STEADY-RATE BOUNDARY FLUXES

| | TO NEW JERSEY

i |_ _ SUBREGIONAL MODEL^

CALCUATE EFFECTIVE 

VERTICAL LEAKANCE 

BETWEEN STREAMS 

AND WATER TABLES

CALIBRATION CHANGES

TO TRANSMISSIVITY

AND CONFINING UNIT

VERTICAL LEAKANCE

I CONVERT SIMULATED

I STEADY-STATE HEADS

INTO INITIAL HEADS

I REGIONAL ,

. 11-LAYER TRANSIENT |

I SIMULATION J

' T

C,M,,, SIMULATION ATOM 

W|JH BOUNDARY FLUXES

CALCULATE AND TRANSFER 

TRANSIENT BOUNDARY 

FLUXES TO NEW JERSEY 

SUBREGIONAL MODEL

CONVERT SIMULATED 

STEADY-STATE HEADS 

INTO INITIAL HEADS

11-LAYER TRANSIENT

SIMULATION 

WITH BOUNDARY FLUXES

7 

I

J 

EXPLANATION

INDICATES WORK THAT IS NOT 

PART OF THE NEW JERSEY 

RASA PROJECT

FIGURE 24. Modeling approach showing relation of New Jersey 

subregional flow model to the northern Atlantic Coastal Plain 

regional and Maryland-Delaware subregional flow models.

subregional flow model grid is rotated about 8.5 degrees 

clockwise from the row direction of the grid used in the 

regional flow model. The cell size of the regional RASA 

grid is 49 mi2 within the New Jersey subregional area. 

The orientation and cell size of the regional grid are 

shown in a representative node (31, 8) in figure 25.

BOUNDARY CONDITIONS

Lateral model boundaries are shown in figure 25. The 

boundaries shown are generalized because they are not 

the same in every aquifer. The northwestern updip limits 

of all the aquifers, except the Holly Beach aquifer (A10), 

are at the Fall Line or are within 15 miles of the Fall Line 

and generally are parallel to it; therefore, the northwest 

model boundary approximates the extent of the Coastal 

Plain sediments at the Fall Line and is represented by a 

no-flow boundary.

The northeast boundary in the 10-layer model roughly 

approximates a flow line in a ground-water discharge 

area in Raritan Bay. The southwest model boundary 

roughly approximates a flow line along a ground-water 

divide between the Delaware Bay and the Chesapeake 

Bay. The northeast and southwest boundaries are simulated as no-flow boundaries in the 10-layer model but as 

flow boundaries in the 11-layer model. To minimize the 

modeled area, the flow boundaries in the 11-layer model 

were located slightly closer to New Jersey than no-flow 

boundaries in the 10-layer model. Boundary flows are 

simulated only for those parts of the aquifers intersecting 

the flow boundaries. Those aquifers with limited extent 

are bounded on the northeast and southwest by no-flow 

boundaries.

The southeast boundaries of the modeled PotomacRaritan-Magothy aquifers (Al, A2, and A3) approximate 

the downdip limit of freshwater. The positions of these 

boundaries are based on the depths to 10,000 mg/L 

chloride concentrations shown by Meisler (1980, fig. 4) 

and on the altitudes of the aquifer tops (figs. 3, 5, and 7). 

These boundaries were represented as no-flow boundaries and are referred to as the interface boundaries in 

this report.

Use of the 10,000 mg/L chloride concentration line as a 

no-flow boundary assumes an idealized saltwaterfreshwater interface. For modeling purposes, water with 

less than 10,000 mg/L chloride concentration is considered freshwater of equal density and nonmixing with 

higher density saltwater. Also, the interface is assumed 

to be stationary. Although it is known that the real 

interface is a transition zone of varying chloride concentrations between freshwater and saltwater, and that this 

transition zone will move in response to head changes in 

the freshwater flow system, the static freshwatersaltwater interface is assumed to be a reasonable
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EXPLANATION

FLOW-BUDGET AREAS See figures 88 to 91 

i

AREA OF LOCAL SURFACE-WATER BODIES (STREAMS)

Recharge of 20 inches per year applied to 

unconfined aquifer outcrop areas

AREA OF REGIONAL SURFACE-WATER BODIES 

(OCEAN AND BAYS) Water-table constant-head 

nodes, no recharge applied

NO-FLOW BOUNDARY IN 10-LAYER MODEL 

SPECIFIED-FLUX BOUNDARY IN 11-LAYER MODEL

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IZJ

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8.44 5.63 3.75 3.75 2.5

GRID SPACING, IN MILES 

FIGURE 25. Finite-difference grid, flow-budget areas, and generalized lateral model boundaries.

2.5

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a
H42 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

approximation of this boundary for both prepumping and 

transient conditions. Sensitivity of simulated water levels to the position of this interface boundary was tested 

and is described in a later section on sensitivity analysis. 

The estimated location of the 10,000 mg/L chloride 

concentration line in the Potomac-Raritan-Magothy aquifers (Al, A2, A3) is shown in figures showing data and 

results for these aquifers. The same boundary locations 

are used for simulation of both prepumping and transient 

conditions. However, it is not suggested that the actual 

10,000 mg/L chloride concentration surface has not 

moved.

The southeastern boundary in the confined Kirkwood 

aquifer and the upper Kirkwood-Cohansey aquifer (A8 

and A9) is the downdip limit of the modeled area. Both 

aquifers extend beyond the southeast model boundary. 

Within these units, freshwater is estimated to be about 

25 to 35 miles further downdip than the model boundary 

based on the depth to chloride concentrations greater 

than 10,000 mg/L as shown by Meisler (1981, fig. 4) and 

on the estimated altitude of these aquifers offshore. This 

southeastern model boundary is a lateral flow boundary 

in the 11-layer model and is assumed to be far enough 

offshore to have little effect on simulated water levels 

onshore. However, simulated water levels were tested 

for sensitivity to the location of this boundary and the 

amount of flow at this boundary. These results are 

described in a later section on sensitivity analysis.

The Englishtown, Wenonah-Mount Laurel, Vincentown, and Piney Point aquifers (A4, A5, A6, and A7) 

have no-flow boundaries (fig. 23) to the southeast that 

represent their actual downdip limits. The Piney Point 

aquifer also has a no-flow boundary to the northwest, and 

the Holly Beach aquifer (A10) is present only in Cape 

May County and has lateral constant-head boundaries 

along the shore.

The lower boundary of the model represents the top of 

the underlying crystalline basement. The boundary is 

no-flow and underlies the lower Potomac-RaritanMagothy aquifer (Al) and the extreme downdip parts of 

the middle Potomac-Raritan-Magothy aquifer (A2) 

where the lower Potomac-Raritan-Magothy aquifer is 

absent. The lower no-flow boundary in very limited 

downdip areas of the middle and upper Potomac-RaritanMagothy aquifers, the Wenonah-Mount Laurel aquifer, 

the Piney Point aquifer, and the lower KirkwoodCohansey and confined Kirkwood aquifer (A2, A3, A5, 

A7, and A8) represents the top of sediments saturated 

with water containing chloride concentrations of 10,000 

mg/L or more.

The upper boundary in the 10-layer model is a 

constant-head boundary representing the altitude of the 

water table in the unconfined parts of the aquifers. This 

boundary includes all of the Holly Beach aquifer (A10),

most of the upper Kirkwood-Cohansey aquifer (A9), and 

the outcrop areas of the Potomac-Raritan-Magothy aquifers, the Englishtown aquifer, the Wenonah-Mount Laurel aquifer, the Vincentown aquifer, and the lower 

Kirkwood-Cohansey aquifer (A1-A6, A8). The Piney 

Point aquifer (A7) has no outcrop or constant-head 

boundary in the modeled area. The lower PotomacRaritan-Magothy aquifer (Al) has no outcrop area or 

constant-head nodes in New Jersey, although there are 

several constant-head nodes representing a small outcrop area in Maryland. Surface-water levels in offshore 

areas are represented as constant-head nodes in the 

estimated outcrop areas of the hydrogeologic units. The 

majority of the offshore constant-head nodes are in the 

Holly Beach aquifer (A10).

The 10-layer model was used to simulate only prepumping steady-state conditions, because the watertable constant-head boundary has the potential to supply 

an infinite amount of recharge to the confined aquifers. 

However, the constant-head boundary of the 10-layer 

steady-state simulations provides the rate of deep percolation (Leahy and Martin, 1986, p. 169). Simulated flow 

to and from the water table is calculated by the model for 

each constant-head node. This flow represents the rate of 

water recharging to or discharging from the underlying 

confined aquifers and will be referred to as deep percolation in this report. Figure 26 shows the schematic 

representation of the upper boundary condition for the 

10-layer model showing deep percolation.

The onshore upper boundary in the 11-layer model is 

constant head, representing long-term stream stage. 

Because of the large cell size in onshore areas (6.25 to 

9.375 mi2) and because there are numerous streams in 

New Jersey, each cell contains at least one stream and 

generally many. Therefore, the stream stage represented by the constant-head node is an average for the 

cell area. In onshore areas of the 11-layer model, the 

unconfined aquifer outcrop areas are active with simulated recharge to the water table. Changes in watertable altitudes caused by pumping can then be simulated 

in the 11-layer model. Figure 26 shows the upper boundary for the 11-layer model. Ground-water recharge is 

applied to nodes that were onshore water-table constanthead nodes in the 10-layer model. The long-term streamstage constant-head nodes in the 11-layer model are in all 

nodes directly overlying previous onshore water-table 

constant-head nodes of the 10-layer model. However, 

constant-head nodes representing stream stage are not 

added above the areas of large surface-water bodies such 

as the ocean and bays (fig. 25). In these offshore areas, 

constant-head nodes in the 10-layer model are unchanged 

in the 11-layer model. No recharge is applied in this area.

To represent the flow between the aquifer outcrop 

areas and the streams, deep percolation calculated at
SIMULATION OF GROUND-WATER FLOW H43

EXPLANATION

BF BASEFLOW

DP DEEP PERCOLATION

ORE GROUND-WATER RECHARGE

GWD GROUND-WATER DISCHARGE

WATER-TABLE HEAD 

STREAM STAGE

STREAM-AQUIFER SYSTEM

TKCB

TKSB

T 

S

CONFINING-UNIT VERTICAL 

LEAKANCE

STREAMBED VERTICAL 

LEAKANCE

TRANSMISSIVITY

AQUIFER STORAGE COEFFICIENT

GWD = BF 

BF = QRE-DP 

TKSB = BF/(hWT -hs

QRE

--, 

hwr

STREAMBED

QRE

DP WATER-TABLE AQUIFER 

CONFINING UNIT

CONFINED AQUIFER

 - _ 

CONFINING UNIT

10-LAYER MODEL

CONFIGURATION

CONSTANT-HEAD 

WATER-TABLE AQUIFER

CONFINING UNIT

AQUIFER

CONFINING UNIT

DATA

hwr

TKCB

T,S

TKCB

11-LAYER MODEL

CONFIGURATION

CONSTANT HEAD 

AT STREAM STAGE

STREAMBED

WATER-TABLE AQUIFER

CONFINING UNIT

AQUIFER

CONFINING UNIT

DATA

hs

TKSB

QRE,T,S

TKCB

T,S

TKCB

FIGURE 26. Schematic representation of stream-aquifer flow, deep percolation, and the upper boundary in the 10-layer and 11-layer models.

each onshore node in the 10-layer model was used to 

calculate the amount of base flow at each node (base flow 

equals ground-water recharge minus deep percolation). 

An effective streambed leakance is calculated, by means 

of Darcy's Law, at each node from the modeled recharge 

rate, simulated deep percolation, and hydraulic gradient 

between the water table and streams. Each cell contains 

many small streams, but one average stream stage was 

estimated for each node. Regional lateral flow in the 

aquifer outcrop areas is assumed to be negligible. The 

calculated streambed leakance does not represent actual 

streambed properties or characteristics for a single 

stream but is a lumped parameter of all the factors 

controlling flow between the water table and streams on 

a regional scale for each node.

The upper model boundary allows the simulated 

water-table level to vary in response to ground-water 

withdrawals but still has the potential to supply an 

unlimited source of water from the simulated streams. 

The upper model boundary does not simulate short-term 

changes in water-table or stream stages caused by 

seasonal changes in recharge or tides. However, the 

upper model boundary is a reasonable representation of 

field conditions as neither long-term or large-scale 

declines in water-table levels nor elimination of streamflow on a regional scale due to ground-water withdrawals 

has been observed. The method of determining the 

altitude of the water table and stream stage for these 

boundaries is discussed in the following section on model 

input data.

MODEL INPUT DATA

Initial estimates of transmissivity were based on 

results from aquifer tests, specific-capacity tests, and 

model simulations of previous studies. A summary of 

hydraulic conductivity determined for each aquifer from 

specific-capacity tests is given in table 5. The hydraulic 

conductivity values were estimated from specificcapacity tests by using equation 6 of McClymonds and 

Franke (1972, p. 11) and multiplied by aquifer thickness 

to obtain the initial transmissivity values. Transmissivity and hydraulic conductivity determined from aquifertest data and model simulations are listed in table 3. 

Some transmissivity values are shown in table 3 with no 

corresponding hydraulic conductivity. Hydraulic conductivity was calculated from these transmissivity values by 

dividing the values by the estimated saturated thickness 

of the aquifer at the location. These hydraulic conductivity values from aquifer and specific-capacity tests were 

used to estimate a range or average hydraulic conductivity for each aquifer. These estimates were then slightly 

modified near State lines to be consistent with hydraulic 

conductivity estimates used in adjacent States.

An average hydraulic conductivity value was used for 

the Englishtown (A4), Wenonah-Mount Laurel (A5), 

Vincentown (A6), Piney Point (A7), and Holly Beach 

(A10) aquifers. These aquifers had very little areal 

variability in hydraulic conductivity. Areally variable 

hydraulic conductivity values were used for each of the 

three Potomac-Raritan-Magothy aquifers (Al, A2, and 

A3) and the two Kirkwood-Cohansey aquifers (A8 and
H44 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

TABLE 5. Summary of hydraulic-conductivity values based on specific-capacity tests and initial estimates of transmissivity

Model 

unit

Al

A2

A3

A4

A5

A6

A7

A8

A9

A10

Aquifer

Lower Potomac-Raritan-Magothy aquifer

Middle Potomac-Raritan-Magothy aquifer

Upper Potomac-Raritan-Magothy aquifer

Englishtown aquifer

Wenonah-Mount Laurel aquifer

Vincentown aquifer

Piney Point aquifer

Lower Kirkwood-Cohansey aquifer and confined Kirkwood

aquifer.

Upper Kirkwood-Cohansey aquifer

Holly Beach aquifer

Number 

of tests

35

104

131

30

22

18

8

33

45

9

Hydraulic conductivity 

(ft/d) 1

Minimum

32

22

29

6

7

10

9

50

50

120

Maximum

527

397

432

130

34

110

95

320

300

180

Average

199

155

135

30

16

42

33

120

178

150

Initial estimated range 

of transmissivity2 (ft2/d)3

860-17,300

860-21,600

860-19,900

90- 5,400

90- 2,300

860- 3,500

260- 5,200

860-19,900

860-25,900

5,200- 7,800

1 ft/A: feet per day.

2 Transmissivity: Estimated prior to model calibration from hydraulic conductivity values and thickness. 

8 ft2/d: feet squared per day.

A9). Generally, the aquifers with the lowest variability 

also had the least amount of available data.

Initial estimates of transmissivity are also given in 

table 5. The Potomac-Raritan-Magothy aquifers, the 

Kirkwood-Cohansey aquifers, and the Holly Beach aquifer (Al, A2, A3, A8, A9, and A10) have the highest 

average hydraulic conductivity (greater than 100 ft/d) 

and the highest initial estimates of transmissivity, except 

for the Holly Beach aquifer, which has a high hydraulic 

conductivity (150 ft/d) but a low initial estimate of 

transmissivity because the unit is relatively thin.

Initial estimates of vertical confining-unit leakance 

were made by dividing an estimate of the vertical 

hydraulic conductivity for each unit by the thickness of 

the unit at each node. Estimates of confining-unit vertical hydraulic conductivity were based on data presented 

in table 4 and on estimated vertical hydraulic conductivity in adjacent states. Only one vertical hydraulic conductivity was used for each confining unit and generally 

approximated to the lowest estimate of hydraulic conductivity for the unit. If no vertical hydraulic conductivity 

was given for a confining unit in table 4, the estimate was 

based on the vertical hydraulic conductivity of other 

units with similar lithologic properties.

In preliminary steady-state simulations, the initial 

estimates of leakance were found to be generally too low, 

particularly in updip areas. Estimates of vertical hydraulic conductivity were then reevaluated and increased 

about two orders of magnitude in updip areas. This 

distribution of a decrease in vertical hydraulic conductivity toward the downdip directions is logical because the 

sediments tend to be finer grained in the downdip 

direction and, therefore, less permeable. Luzier (1980, 

fig. 9) used a similar distribution for the MerchantvilleWoodbury confining unit. Estimates of leakance based 

on the reevaluated vertical hydraulic conductivity

values varied from three to four orders of magnitude 

within each confining unit because confining units 

thicken and grain size is finer in the downdip direction.

Storage coefficients determined from aquifer-test data 

(table 3) were used to estimate one representative storage coefficient for all the aquifers. The storage coefficient 

data range from 1.5 xl(T5 to S.lxlO"2. The highest 

values are generally near the aquifer outcrop areas and 

indicate unconfined or partially confined conditions. A 

single confined storage coefficient of l.OxlO"4 was used 

for each of the aquifers. In unconfined areas, a specific 

yield of 0.15 was used. These coefficients are approximate means for all of the aquifers and were the same as 

the values used in other States for the northern Atlantic 

Coastal Plain RASA study. Generally, these values were 

not changed during model calibration.

Prepumping water-table altitudes for the upper 

boundary of the 10-layer model were estimated by using 

measured water levels and long-term stream stages, 

which were estimated by using topographic maps. 

Water-table altitudes between surface-water bodies 

were based on the altitude and configuration of land 

surface and measured water levels. Water-table altitudes are shown in figure 27. The altitudes are generalized because they were estimated for periods of average 

precipitation or ground-water recharge under prepumping conditions.

The effective long-term stream altitudes for the upper 

boundary of the 11-layer model were estimated to be the 

average altitude of the largest stream segment from 

topographic maps. All nodal stream altitudes are less 

than the water-table altitudes at that node. Therefore, 

under prepumping conditions, the streams are simulated 

as discharge points from the aquifers. Although the 

simulated streams are discrete points and not a continuous surface, stream altitudes have been contoured and
40° 75°

- 25

39°

PENNSYLVANIA FALL LINE

74°

40°

a ro 2o^

o so 

o a

i

75°

0 5 10 15 MILES

0 5 10 15 KILOMETERS

EXPLANATION

50 WATER-TABLE CONTOUR Shows altitude of 

water table. Contour interval 25 feet. 

National Geodetic Vertical Datum of 1929

74° 39° 

FIGURE 27. Generalized altitude of the water table, prepumping conditions.

a£>.cn
H46 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

> LO

O "

if 1 §*

O 3

I

13
SIMULATION OF GROUND-WATER FLOW H47

TABLE 6. Summary of hydrologic budget analyses used to estimate ground-water recharge

Precipitation 

(in/yr)

44

45

44

43^6

44.2

41

Evapotranspiration 

(in/yr)

23

22.5

22

23-26

24.0

25

Runoff (in/yr) 1

Surface Ground-water Total

- - 21

2.5 20 22.5

- - 22

- - 17-20

- - 20.2

4 12 16

- - 20-21

 

 

Other 

(in/yr)

up to 2.82

4-113

4-83

Location

Delaware River Basin

Pine Barrens Region central

and southeast Coastal Plain.

Gloucester County

Burlington County

New Jersey Coastal Plain

Nanicoke River Basin, Kent

and Sussex Co. , Del.

Potomac-Raritan-Magothy

outcrop area.

Potomac-Raritan-Magothy

outcrop area.

Farrington aquifer system

outcrop area.

Reference

Parker and others (1964, p.

14).

Rhodehamel (1970, p. 5, 6,

16, and 18).

Hardt and Hilton (1969, p.

54).

Rush (1968, p. 16-18).

Vowinkel and Foster (1981,

p. 18).

Johnston (1976, p. 39).

Barksdale (1958, p. 102).

Luzier (1980, p. 32).

Farlekas (1979, p. 32).

1 in/yr: inches per year.

2 Deep regional ground-water recharge, a part of ground-water runoff.

3 Ground-water recharge, a part of ground-water runoff.

are shown in figure 28. The generalized altitudes are 

estimated for periods of average precipitation or streamflow. These contours provide a means to compare stream 

altitudes to water-table altitudes and to analyze the areal 

variation in stream altitudes. However, there is no 

intention to suggest that these contours represent a 

continuous stream surface.

Recharge to the outcrop areas in the 11-layer model is 

equal to long-term precipitation minus long-term evapotranspiration and can be directly measured as long-term 

streamflow. Streamflow consists of surface runoff and 

ground-water discharge. Ground-water discharge is 

water that initially recharged aquifers and later discharged to streams. Ground-water discharge may be (1) 

local flow to nearby streams within shallow aquifers, (2) 

intermediate flow moving along longer flow paths 

beneath nearby streams and discharging to neighboring 

larger streams, or (3) regional flow moving through the 

deep confined aquifers and eventually discharging to 

large rivers or surface-water bodies. The upper boundary in the 11-layer model, with recharge to the water 

table and constant-head nodes representing the stream 

stage, simulates surface runoff and local ground-water 

discharge as flow through one or two cells (less than 5 mi) 

of the outcrop areas, whereas intermediate and regional 

ground-water discharge is simulated as deep percolation 

that has moved longer distances through the confined 

aquifers.

Water-budget estimates were used to determine an 

estimate of ground-water recharge to the water-table 

aquifer for the 11-layer model (table 6). A value of 20 

in/yr was used to represent the long-term and areal

average ground-water recharge in the New Jersey 

Coastal Phin. This value is consistent with values shown 

in table 6 and those used in the northern Atlantic Coastal 

Plain RASA studies in adjacent States (15 in/yr in 

Maryland and 22.5 in/yr in Long Island, N.Y.). This 

value is also consistent with average stream discharge. 

The average stream discharge for 16 streams with 

surface-water basins within the New Jersey Coastal 

Plain was 22.2 in/yr in 1981.

Ground-water withdrawal data presented by Zapecza, 

Voronin, and Martin (1987, tables 2 and 3) for 1918 

through 1980 are used in the New Jersey Coastal Plain 

area of the model. The latitude and longitude of wells and 

well fields are used to identify the nodes to which 

withdrawals are applied. Figure 29 shows total annual 

withdrawals in the New Jersey Coastal Plain and the 

averaged withdrawal rates for each of nine pumping 

periods from 1896 through 1980.

The pumping periods are 3 to 25 years long. Withdrawals for each pumping period are also given in table 7. 

Time discretization was based not only on changing 

withdrawal rates in New Jersey but also on historical 

withdrawal rates from other States within the northern 

Atlantic Coastal Plain. The regional RASA model and 

subregional models for each of the other States used 

pumping periods equivalent to those in the New Jersey 

subregional model.

The average withdrawals in New Jersey for pumping 

period 1 (1896 to 1921) are estimated to be one-half of the 

1920 withdrawal rate. Withdrawals for Pennsylvania 

(R.A. Sloto, written commun., 1983) and Delaware 

(W.B. Fleck, written commun., 1983) were estimated
H48 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

400

350

300

250

200

150

100

50 -

3 PUMPING PERIOD

TOTAL ANNUAL 

WITHDRAWALS

AVERAGE WITHDRAWALS

FOR EACH 

PUMPING PERIODESTIMATED 

WITHDRAWALS [ r1 2

1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990

FIGURE 29. Total annual ground-water withdrawals and average 

withdrawals for each pumping period for the New Jersey Coastal 

Plain.

from data compiled for modeling studies in those States 

by the U.S. Geological Survey. Withdrawals for the 

relatively small areas of these States that are included in 

the model are given in table 7. Withdrawals for Pennsylvania and Delaware areas are from 5 to 16 percent of 

total withdrawals for each pumping period.

Lateral boundary flows for the 11-layer steady-state 

and transient model were calculated by using simulated 

water levels and transmissivity values from the regional 

RASA model. Flows were calculated by using water 

levels simulated by the prepumping steady-state model 

and water levels simulated at the end of each pumping 

period by the transient model. Calculated flows were 

assumed to represent flow across the boundaries for the 

following pumping period and to be constant throughout 

the pumping period. Flows calculated from the regional 

prepumping simulations were used m the New Jersey 

subregional flow model for the prepumping simulation 

and pumping period 1. Total boundary flows for each 

pumping period are shown in table 7. Flows along each 

boundary for prepumping conditions and pumping period 

8 are discussed further for each aquifer and boundary in 

the later section on the sensitivity analysis of boundary 

flows.

TABLE 7. Ground-water withdrawals and lateral boundary flows 

for each pumping period

[Boundary flows: Positive boundary flows are out of model area, negative 

boundary flows are into model area. Difference between flows for any pumping 

period and prepumping flows is the source of water to wells in table 13. Total 

flow: Sum of withdrawals and boundary flows. Mgal/d: Million gallons per day.]

Pumping period End date

Withdrawals (Mgal/d) Boundary

New Jersey Pennsylvania flows

Total 

flow

<»***> (Mgal/d)

prepumping

1

2

3

4

5

6

7

8

9

1-1-1896

1-1-1921

1-1-1946

1-1-1953

1-1-1958

1-1-1965

1-1-1968

1-1-1973

1-1-1978

1-1-1981

0

24.6

75.2

127.3

158.1

215.3

253.7

303.7

331.1

341.7

0

1.8

10.8

23.5

16.7

19.6

20.3

21.9

19.8

16.5

4.7

4.7

4.4

3.8

2.2

0.7

-1.3

-3.2

-5.2

-5.6

4.7

31.1

90.4

154.5

177.0

235.6

272.7

322.4

345.7

352.6

MODEL CALIBRATION

APPROACH

Calibration was achieved primarily by a trial-anderror adjustment of aquifer transmissivity and confiningunit vertical hydraulic conductivity. Generally, simulated water levels are affected most by changes in these 

hydraulic characteristics. However, the altitude of the 

water table, stream stages, and aquifer storage coefficients were also adjusted slightly during calibration. 

Simulated water levels were tested for sensitivity to 

other model input data and to several boundary conditions during and after the calibration process.

The 10-layer steady-state model was used to roughly 

calibrate aquifer and confining-unit properties by comparing simulated prepumping potentiometric surfaces to 

measured prepumping water levels. The measured prepumping water levels and potentiometric surfaces for the 

Coastal Plain aquifers are shown and discussed by 

Zapecza, Voronin, and Martin (1987). Prepumping 

potentiometric surfaces are available for all aquifers 

except the lower and middle Potomac-Raritan-Magothy 

aquifers (Al and A2), which had only sparse prepumping 

water-level data. The steady-state model provided an 

efficient method of obtaining rough estimates of the 

hydraulic characteristics. Simulated prepumping water 

levels changed slightly during calibration of the transient 

flow system as more measured water levels provided a 

basis for more rigorous calibration. Therefore, the calibration of the transient flow system and the final calibration of the prepumping flow system were done simultaneously with similar changes in model input data made 

in the 10-layer and 11-layer steady-state models and in 

the 11-layer transient model.

The 11-layer model was calibrated to transient water 

levels by attempting to match interpreted 1978
SIMULATION OF GROUND-WATER FLOW H49

potentiometric surfaces and long-term well hydrographs. 

Interpreted 1978 potentiometric surface maps by Walker 

(1983, fig. 9 and pis. 1-5) are available for the following 

aquifers: the upper Potomac-Raritan-Magothy aquifer 

system (A3), the Englishtown aquifer (A4), the 

Wenonah-Mount Laurel aquifer (A5), the confined Kirkwood aquifer (A8), and the confined part of the upper 

Kirkwood-Cohansey aquifer (A9). Walker (1983) refers 

to the lower and middle Potomac-Raritan-Magothy aquifers of this study as the lower aquifer of the PotomacRaritan-Magothy aquifer system. Data for the 1978 

potentiometric surface for the undifferentiated lower and 

middle aquifers (Walker, 1983, pi. 1) were reanalyzed to 

make separate maps for each aquifer. Potentiometric 

surface maps for 1978 are not available for the Vincentown aquifer (A6), Piney Point aquifer (A7), the unconfined lower and upper Kirkwood-Cohansey aquifers (A8 

and A9), and the Holly Beach aquifer (A10). Simulated 

potentiometric surfaces for these aquifers are compared 

to measured water levels.

Data for the interpreted 1978 potentiometric surfaces 

were collected over a period of several months but 

primarily in October or November of 1978. However, 

pumping period 8 ends closest to this date on January 1, 

1978. Although the dates of the simulated and interpreted transient water-level surfaces differ in time by at 

least 10 months, their comparison is adequate for simulating the regional flow system. In areas with observation wells, water-level declines from 1973 to 1978 averaged 1 to 4 ft/yr (Walker, 1983). At this rate water-level 

declines from January 1, 1978, to October or November 

1978 would be much less than the calibration criteria of 

15 feet (described below). The simulated January 1,1978, 

and interpreted October/November 1978 potentiometric 

surfaces are referred to as the simulated and interpreted 

1978 potentiometric surfaces, respectively, in this 

report.

Well hydrographs also were used for calibration. Simulated water levels at the end of each pumping period 

were compared to the measured water levels closest to 

the end of the pumping period. Comparison of well 

hydrographs to simulated water levels provided more 

accuracy than using only potentiometric surface maps. 

The use of well hydrographs also minimized the error in 

comparing the simulated and interpreted 1978 surfaces 

with dates that differed by 10 months. Simulated hydrographs are compared to measured water levels presented by Zapecza, Voronin, and Martin (1987, pis. 1-10) 

for the period 1924 to 1984 for each aquifer. However, 

most wells do not have water-level data for the entire 

period. Hydrographs for wells in the undifferentiated 

Potomac-Raritan-Magothy aquifer system are assigned 

to the lower or middle aquifer based on the altitude of the 

well screen intervals and the altitude of the lower (fig. 3)

or middle (fig. 5) aquifer. Likewise, hydrographs for the 

undifferentiated Kirkwood-Cohansey aquifer system are 

assigned to the lower Kirkwood-Cohansey aquifer and 

confined Kirkwood aquifer (A8) and the upper KirkwoodCohansey aquifer (A9) based on the screen intervals and 

the altitudes of the tops of the aquifers shown in figures 

17 and 19.

A total of 89 well hydrographs were selected for model 

calibration from the hundreds of wells in the New Jersey 

Coastal Plain measured by the U.S. Geological Survey. 

These well hydrographs were selected on the basis of 

their location and period of record. Most wells are in the 

updip parts of the aquifers, although records for some 

deeper wells in downdip areas are available. Most wells 

have periods of recorded water-level measurements of at 

least 15 years, and several wells have records of more 

than 50 years. Seven to 13 well hydrographs were used 

for each aquifer. Only the Vincentown aquifer (A6), with 

one well, has an insufficient number of wells with 

recorded water levels for calibration.

Simulated water levels were used to generate simulated hydrographs for observation-well sites at points 

other than the nodes for comparison with well hydrographs. A linear interpolation based on the location and 

simulated water levels at the three nodes nearest to the 

observation well was used to calculate the simulated 

hydrograph of that well. The simulated water levels at 

the three nodes define a plane, which is assumed to 

approximate water levels between these points. The 

altitude of the plane at the site of the measured water 

level is determined by the location of the observationwell site with respect to the three nodes. The model code 

was modified to calculate the simulated hydrographs 

using this three-node method.

Determining the acceptability of the match between 

simulated and interpreted potentiometric surfaces and 

hydrographs is subjective. The attempt was made to 

match interpreted 1978 potentiometric surfaces as 

closely as possible and hydrographs to within 10 feet. 

Calibration was considered acceptable when the following criteria were satisfied:

1. The interpreted 1978 potentiometric surfaces (including the depths of the cones of depression) were 

reproduced to within 15 feet, and the locations and 

configurations of the simulated cones were reasonable.

2. The interpreted prepumping steady-state potentiometric surfaces were reproduced to within 15 feet.

3. Simulated hydrographs matched the measured hydrographs to within 15 feet at the end of each pumping 

period.

4. Simulated water levels in areas with little or no 

measured data were compatible to water levels in
H50 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

areas with data and were compatible with flow 

directions postulated in the conceptual model. 

5. Hydraulic characteristics representing the flow system (including aquifer transmissivity, confiningunit vertical hydraulic conductivity, flow rates 

between the aquifers, and flow between the unconfined aquifer and the streams) were compatible to 

measured aquifer and confining-unit characteristics 

and to flow rates postulated in the conceptual 

model.

The model is more rigorously calibrated in some areas 

than others. The degree of calibration depends on the 

distribution of measured data, the character of the 

hydrogeologic framework and potentiometric surfaces in 

relation to the cell size, the sensitivity of simulated water 

levels to data changes, and the ease with which calibration was achieved. Generally, the Vincentown aquifer 

(A6) and offshore areas of the aquifer system were 

calibrated only according to the fourth and fifth calibration criteria and are not considered to be well calibrated. 

Also, calibration within the outcrop areas of the confined 

aquifers is severely limited by the cell size. The area of 

the outcrops in any cell is generally much less than the 

cell size. The model outcrop areas provide a means for 

simulated regional recharge to the confined aquifers, but 

local unconfined water levels or flow rates are not 

simulated accurately in these areas.

SIMULATION OF PREPUMPING STEADY-STATE 

CONDITIONS

Generally, the match between simulated and interpreted prepumping potentiometric surfaces is considered 

acceptable, although in some areas of some aquifers 

there is not a good match. Figures 30 to 39 show the 

simulated surfaces and, when available, the interpreted 

prepumping potentiometric surfaces. The interpreted 

surfaces show contours based on measured data. Discussion of the comparison of the- simulated and interpreted 

surfaces follows.

The simulated prepumping potentiometric surfaces for 

the lower and middle Potomac-Raritan-Magothy aquifers 

(Al and A2) are shown in figures 30 and 31. The 

interpreted and simulated prepumping surfaces for the 

upper aquifer (A3) are shown in figure 32. The high 

ground-water altitudes near the outcrop in Middlesex 

County and the low altitudes near the outcrop area along 

the Delaware River, near Raritan Bay, and along the 

Atlantic Coast in Ocean and Monmouth Counties are 

simulated in all three aquifers. However, the lateral 

gradient from the outcrop area in Mercer and Middlesex 

Counties to the discharge area beneath the Atlantic 

Ocean in the upper aquifer is not closely simulated, and 

simulated water levels along the Atlantic Coast may be 

10 to 15 feet higher than actual water levels.

The simulated and interpreted prepumping potentiometric surfaces for the Englishtown aquifer (A4) are 

shown in figure 33. The high ground-water altitudes near 

the outcrop in northwestern Monmouth County, the 

enclosed ground-water low in the outcrop in western 

Burlington County, and the low ground-water altitudes 

beneath Raritan Bay, the Atlantic Coast, and the outcrop area in Gloucester and Camden Counties are all 

simulated. Two small enclosed ground-water highs near 

the outcrop in Burlington and Gloucester Counties and 

the lateral gradient between the outcrop in Monmouth 

County and the Atlantic Coast were not simulated. Also, 

the simulated surface shows a ground-water high in 

Camden County that is lower, smaller, and further north 

in the interpreted potentiometric surface. The small 

enclosed highs near the outcrop may be too small in 

comparison to the cell size to be accurately simulated. 

Nevertheless, the general ground-water altitudes are 

approximately simulated in these areas. The larger simulated ground-water high in Camden County differs from 

the interpreted potentiometric surface because the interpreted surface probably does not represent true prepumping conditions and reflects water levels lowered by 

small amounts of unrecorded local pumpage. As in the 

Potomac-Raritan-Magothy aquifers, ground-water gradients in Monmouth County are not closely simulated, 

and simulated water levels along the coast may be 15 feet 

higher than actual prepumping water levels in the 

Englishtown aquifer.

The closely matched simulated and interpreted potentiometric surfaces for the Wenonah-Mount Laurel aquifer (A5) are shown in figure 34. Only minor differences 

are seen. The local ground-water highs or lows based on 

a single data point may be incorrect on the interpreted 

potentiometric surface map or may not be large enough 

in relation to the cell size to be simulated. Generally, the 

simulated prepumping flow patterns in the WenonahMount Laurel aquifer are similar to those in the Englishtown aquifer (A4) (fig. 33). Ground-water altitudes are 

high near the outcrop in Monmouth and Camden Counties and low near the outcrop in Burlington and Salem 

Counties and in most of the southeastern Coastal Plain 

and along the Atlantic Coast.

The simulated and interpreted prepumping potentiometric surfaces for the Vincentown aquifer (A6) are 

shown in figure 35. Generally, the simulated potentiometric surface for the Vincentown aquifer (A6) is similar 

to the potentiometric surface for the underlying areas of 

Wenonah-Mount Laurel aquifer (A5) (fig. 34), as waterlevel differences between these aquifers are less than 5 

feet, except at the Atlantic Coast in Monmouth County. 

The simulated water levels for the Vincentown aquifer 

approximate the measured water levels only generally. 

Most of the localized areas of high or low ground-water
SIMULATION OF GROUND-WATER FLOW H51

tJ 

g

O

a

a 

eO,

1
H52 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN
SIMULATION OF GROUND-WATER FLOW H53

 s

1

I

I

-o

I I
40° 75°

39°

PENNSYLVANIA FALL LINE X

75°

EXPLANATION

OUTCROP AREA OF THE ENGLISHTOWN FORMATION IN NEW JERSEY

0 5 10 15 MILES

0 5 10 15 KILOMETERS

30 SIMULATED POTENTIOMETRIC CONTOUR Shows altitude 

of simulated prepumping potentiometric surface. Contour 

interval 1 0 and 20 feet. National Geodetic Vertical Datum of 1 929

40 INTERPRETED POTENTIOMETRIC CONTOUR Shows altitude 

of interpreted prepumping potentiometric surface. Contour 

interval 20 feet. National Geodetic Vertical Datum of 1929

74°

40°

 Od

CO

H<

COCO I I COI

O 

ffi

O O

74° 39° Interpreted prepumping potentiometric contours from Zapecza, Voronin, and Martin (1987, fig. 5). 

FIGURE 33. Simulated and interpreted prepumping potentiometric surfaces for the Englishtown aquifer (model unit A4).
40° 75°

39°

75°

EXPLANATION

OUTCROP AREA OF THE WENONAH FORMATION AND 

MOUNT LAUREL SAND IN NEW JERSEY

5 10 15 MILES

_i____i____i

0 5 10 15 KILOMETERS

30 SIMULATED POTENTIOMETRIC CONTOUR Shows altitude 

of simulated prepumping potentiometric surface. Contour 

interval 10 and 20 feet. National Geodetic Vertical Datum of 1929

40 INTERPRETED POTENTIOMETRIC CONTOUR Shows altitude 

of interpreted prepumping potentiometric surface. Contour 

interval 20 feet. National Geodetic Vertical Datum of 1929

74°

40°

CO i i

gd

O 

52! 

O

^

§Od

52!a

74° 39° Interpreted prepumping potentiometric contours from Zapecza, Voronin, and Martin (1987, fig. 6). 

FIGURE 34. Simulated and interpreted prepumping potentiometric surfaces for the Wenonah-Mount Laurel aquifer (model unit A5).

Cn
ffi Cn

OS

75

40'

PENNSYLVANIA

I T v \^ DOWNDIP LIMIT OF/lQ^-

GLOUCESTER! CAMDEN*

BURLINGTON /

OUTCROP AREA OF THE VINCENTOWN FORMATION 

IN NEW JERSEY

30 SIMULATED POTENTIOMETRIC CONTOUR Shows altitude 

of simulated prepumping potentiometric surface. Contour 

interval 10 and 20 feet. National Geodetic Vertical Datum of 1929

40 INTERPRETED POTENTIOMETRIC CONTOUR Shows altitude 

of interpreted prepumping potentiometric surface. Contour 

interval 20 feet. National Geodetic Vertical Datum of 1929

0 5 10 15 KILOMETERS

40°

74° 39° Interpreted prepumping potentiometric contours from Zapecza, Voronin, and Martin (1987, fig.7). 

FIGURE 35. Simulated and interpreted prepumping potentiometric surfaces for the Vincentown aquifer (model unit A6).

SO 

HO

HH

O

, > 

e!

SO

Q Q O
40° 75°

39°75°

PENNSYLVANIA FALL LINE

^ \ > 

SALEM ^ GLOUCESTER JCAMDEN /

MONMOUTH

10 15 MILES

EXPLANATION

 40 SIMULATED POTENTIOMETRIC CONTOUR Shows altitude 

of simulated prepumping potentiometric surface. Contour 

interval 20 feet. National Geodetic Vertical Datum of 1929

- 50 INTERPRETED POTENTIOMETRIC CONTOUR Shows altitude 

of interpreted prepumping potentiometric surface. Contour interval 25 feet. National Geodetic Vertical Datum of 1929

0 5 10 15 KILOMETERS

74°

40°

CQ

QO C

i

74° 39° Interpreted prepumping potentiometric contours from Zapecza, Voronin, and Martin (1987, fig.8). 

FIGURE 36. Simulated and interpreted prepumping potentiometric surfaces for the Piney Point aquifer (model unit A7).
H58 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

1

 § 

o

~

 § §"<?2 

3 -

05 ,0) d) **H

 O rt

 c

" gI

t

I

I

73

a

73

03 

W
40° 75°

39°75°

10 15 MILES

0 5 10 15 KILOMETERS

___ UPDIPjJMIT OF OVERLYING CONF1NING^NITJC9)_

EXPLANATION

 30 SIMULATED WATER-TABLE AND POTENTIOMETRIC CONTOUR 

Shows altitude of simulated prepumping water table and potentiometric surface. Contour interval 10 and 20 feet. 

National Geodetic Vertical Datum of 1929

- 60 INTERPRETED WATER-TABLE CONTOUR Shows altitude

of interpreted prepumping water table. Contour interval 40 feet. 

National Geodetic Vertical Datum of 1929

74°

40°

pHOizj

O

O 

O

3

O

|Hi

74° 39° Interpreted prepumping water-table contours from Zapecza, Voronin, and Martin (1987, fig.10). 

FIGURE 38. Simulated and interpreted prepumping water tables and potentiometric surfaces for the upper Kirkwood-Cohansey aquifer (model unit A9).

w
H60 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

74° 45'

39° 15'

39°

/

EXPLANATION

"u.

 10 

75 

SIMULATED WATER-TABLE CONTOUR Shows altitude of 

simulated prepumping water table. Contour interval 5 feet. 

National Geodetic Vertical Datum of 1929

INTERPRETED WATER-TABLE CONTOUR Shows altitude of 

interpreted prepumping water table. Contour interval 5 feet. 

National Geodetic Vertical Datum of 1929

CAPE MAY COUNTY

DELAWARE 

BAY

4 MILES

4 KILOMETERS

Base from U.S. Department of Agriculture, 

Soil Conservation Service, 1:250,000,1980

Interpreted prepumping water-table contours from 

Zapecza,Voronin, and Martin (1987, fig. 11).

FIGURE 39. Simulated and interpreted prepumping water tables for the Holly Beach aquifer (model

unit A10).

altitudes cannot be simulated because of the large cell 

size. Also, the outcrop area for the Vincentown aquifer is 

poorly represented by the large cell size; therefore, local 

recharge and discharge areas cannot be simulated accurately.

The simulated and interpreted prepumping potentiometric surfaces for the Piney Point aquifer (A7) are 

shown in figure 36. Potentiometric contours are closely 

simulated except in the southwestern Coastal Plain and 

along the Atlantic Coast where simulated contours are 

about 20 feet higher than the interpreted contours.

Normally, a 20-ft difference between the simulated and 

interpreted potentiometric surfaces over a large area is 

not acceptable. However, the general trend of the potentiometric surface has been simulated, and relatively few 

water-level measurements are available; therefore, further calibration was not considered beneficial.

The simulated and interpreted prepumping potentiometric surfaces for the lower Kirkwood-Cohansey aquifer and the confined Kirkwood aquifer (A8) are shown in 

figure 37. The simulated potentiometric surface matches 

the interpreted potentiometric surface closely in the
SIMULATION OF GROUND-WATER FLOW H61

confined parts of the aquifer. In the unconfined areas, 

water-level altitudes in the lower Kirkwood-Cohansey 

aquifer are very similar to the water-table altitudes in 

the overlying upper Kirkwood-Cohansey aquifer (A9) 

and strongly reflect the local flow patterns determined 

by stream drainage patterns. In the confined Kirkwood 

aquifer (A8), local flow patterns are less apparent, and 

simulated water levels decrease downdip from the western extent of the confining unit to beneath the Atlantic 

Ocean.

The interpreted prepumping potentiometric surfaces 

for the upper Kirkwood-Cohansey aquifer (A9) and the 

Holly Beach aquifer (A10) are almost entirely watertable surfaces, and potentiometric contours are closely 

controlled by local streams. These potentiometric surfaces have been simulated as closely as possible with the 

cell size used in the model. The simulated and interpreted surfaces for the upper Kirkwood-Cohansey aquifer and the Holly Beach aquifer are shown in figures 38 

and 39, respectively. Generally, the altitude of the 

simulated water table is more than 100 feet above sea 

level in central Ocean, central Burlington, central Camden, and central Gloucester Counties. Low water-table 

altitudes are simulated near the Atlantic Ocean and 

Delaware Bay coastlines and along large rivers.

Flow to and from the confined aquifers and flow to and 

from streams were analyzed for prepumping steadystate conditions to determine whether the simulated 

flows are comparable to rates and areas of recharge and 

discharge postulated in the conceptual model. In the 

10-layer steady-state simulations, flow between the 

unconfined outcrop areas and the underlying confined 

aquifers is represented by flow to and from the watertable constant-head nodes in the unconfined parts of all of 

the model units, except the lower Potomac-RaritanMagothy aquifer (Al) and the Piney Point aquifer (A7), 

which have no water-table constant-head nodes, as they 

are completely confined in New Jersey.

Simulated flow to and from the confined aquifers for 

prepumping conditions is shown in figure 40. Flow to and 

from the confined aquifers is flow to and from the 

water-table constant-head nodes in the 10-layer steadystate model. Generally, simulated recharge and discharge rates for the confined aquifers are less than 5 

in/yr. However, the largest discharge to the water table 

is 8 in/yr, and the largest recharge to the confined 

aquifers is 9 in/yr. These high values are not shown in 

figure 40 because of the 5 in/yr interval but are in the 

area where the upper Kirkwood-Cohansey aquifer (A9) 

directly overlies the lower Kirkwood-Cohansey aquifer 

(A8) with no intervening confining unit. In this area, 80 

percent of the recharge and discharge values are from 0.0 

to 4.5 in/yr. Steady-state calibration of the lower and 

upper Kirkwood-Cohansey aquifers (A8 and A9) included

decreasing transmissivity of these units to decrease the 

amount of flow between the two aquifers in this area to 

less than 15 in/yr.

In most of the other onshore areas in New Jersey, 

simulated flow represents flow to or from the unconfined 

aquifer outcrops through an underlying confining unit to 

a confined aquifer. In these areas with an underlying 

confining unit, 90 percent of the recharge and discharge 

values are less than 1.5 in/yr. Simulated discharge from 

the confined aquifers in offshore areas is generally less 

than 0.01 in/yr.

Simulated recharge areas coincide with land-surface 

highs, and discharge areas coincide with low areas along 

streams and large surface-water bodies. Highest 

recharge and discharge rates are simulated in areas 

where there is no underlying confining unit to impede 

flow, and flow in areas with an underlying confining unit 

is only a small part, less than 10 percent, of the assumed 

20 in/yr of recharge.

In the 11-layer steady-state model, flow from 

constant-head nodes representing stream stages simulates prepumping flow between the water-table and the 

streams. Simulated flow to streams is shown in figure 41. 

Generally, flow to streams is between 10 and 30 in/yr, 

although the highest flow is 38 in/yr and the lowest is 7 

in/yr. The extreme values of simulated flow to streams 

are not shown in figure 41 because of the 5 in/yr interval 

but are in the area where the lower and upper of the 

Kirkwood-Cohansey aquifers (A8 and A9) have no intervening confining unit. In this area, about 70 percent of 

the simulated base-flow values are from 13.5 to 26.5 

in/yr. In other areas, where the water-table aquifer is 

underlain by a confining unit, about 90 percent of the 

flow to streams is from 16.5 to 23.5 in/yr. The difference 

between the 20 in/yr of simulated recharge to the water 

table and the flow to streams is vertical and lateral flow 

from or to the unconfined outcrop areas. In areas where 

the flow to streams is less than 20 in/yr, ground-water 

flow is laterally and vertically out of the unconfined 

outcrop areas into confined aquifers, and in areas where 

flow to streams is more than 20 in/yr, ground-water flow 

is laterally and vertically from confined aquifers into the 

unconfined outcrop areas and then upward to streams.

Areas with more than 20 in/yr of flow to streams 

coincide with onshore discharge areas along major 

streams, and areas with less than 20 in/yr of flow to 

streams coincide with onshore recharge areas. In areas 

where the unconfined outcrop areas are underlain by a 

confining unit, most of the 20 in/yr of recharge flows to 

the streams, and simulated flow to streams is generally 

within 3.5 in/yr of this recharge value. In the area where 

there is no confining unit underlying the outcrop areas, 

flow to the streams is generally within 10 in/yr of the 20 

in/yr of the applied recharge.
ffi

O5 ISO

/3 ____________ .NftSYLVANIA -~^ ^-\

AREA OF DOWNWARD RECHARGE INTO CONFINED AQUIFERSAREA OF UPWARD DISCHARGE FROM CONFINED AQUIFERS

LINE OF EQUAL SIMULATED PREPUMPING FLOW FROM AND TO THE UNCONFINED OUTCROP 

AREAS Interval 5 inches per year 75

H 

OI-HoI I

H

M HO 

O

74° 39°

FIGURE 40. Simulated prepumping ground-water flow from and to the unconfined outcrop areas in the 10-layer model.
40° 75°

39°

75°

DEL AW ARE

I 

A Y

0-

0 5 10 15 KILOMETERS

EXPLANATION

RECHARGE AREAS TO THE PREPUMPING GROUNDWATER FLOW SYSTEM Simulated flow to streams is 

less than the applied recharge rate of 20 inches per year

DISCHARGE AREAS TO THE PREPUMPING GROUNDWATER FLOW SYSTEM Simulated flow to streams is 

greater than the applied recharge rate of 20 inches per year

LINE OF EQUAL SIMULATED PREPUMPING FLOW TO STREAMS Interval 5 inches per year

03OXo ^j

o » 

o d X

Gfi

y74° 39°

FIGURE 41. Simulated prepumping ground-water flow to streams in the 11-layer model.
H64 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

SIMULATION OF TRANSIENT CONDITIONS

Generally, the interpreted 1978 potentiometric surface 

is simulated closely by the transient model results. 

Figures 42 to 51 show both the simulated and interpreted 

1978 potentiometric surfaces. A comparison of simulated 

and measured water levels at the end of each pumping 

period is shown in table 15, which follows the references 

cited section. Simulated and measured hydrographs are 

shown in figures 52 to 54 for the three Potomac-RaritanMagothy aquifers (Al, A2, and A3), the Englishtown 

aquifer (A4), the Wenonah-Mount Laurel aquifer (A5), 

and the confined Kirkwood aquifer (A8), and the upper 

Kirkwood-Cohansey aquifer (A9). The configuration of 

the potentiometric surfaces has been simulated closely in 

most of the aquifers, although in some areas, and in some 

aquifers, the match between simulated and interpreted 

potentiometric surfaces is poor. However, the match 

between simulated and measured hydrographs is considered to be good. The comparison of simulated and 

measured transient water levels is discussed for each 

aquifer below.

In the lower Potomac-Raritan-Magothy aquifer (Al), 

the center of the large cone of depression centered in 

Camden County is simulated (fig. 42) about 10 feet 

shallower than the interpreted cone. Simulated water 

levels near the Delaware River do not show local variations in the potentiometric surface. Simulated hydrographs for wells 7-354 and 15-296 (table 15) average 

about 11 feet lower than the measured water levels and 

the simulated hydrograph for well 15-323 (table 15) 

averages about 18 feet above measured water levels. 

These differences are mostly the result of discretization 

scale, because the simulated hydrographs were calculated from water levels averaged over large cell areas.

The interpreted potentiometric surface of the middle 

Potomac-Raritan-Magothy aquifer (A2) has been closely 

simulated, generally, to within 10 feet (fig. 43). However, the centers of the simulated cones of depression are 

as much as 20 feet shallower than the interpreted cones 

because of the large cell size. A moderate-sized cone at 

Artificial Island in Salem County has not been simulated, 

possibly because of incorrect or insufficient simulated 

withdrawal data. The only large area considered to be 

poorly simulated is downdip in Burlington and Ocean 

Counties. This area has simulated water levels 15 to 25 

feet lower than measured water levels, as shown in table 

15 for well 29-19.

The interpreted and simulated 1978 potentiometric 

surfaces of the upper Potomac-Raritan-Magothy aquifer 

(A3) flow system are shown in figure 44. Water levels in 

the large cone centered in Camden County and the high 

ground-water altitudes near the outcrop areas in Mercer 

and Middlesex Counties are simulated to within 10 feet of 

measured water levels. However, the downdip area

along the coast in Monmouth and Ocean Counties is 

poorly simulated. Although no water levels were measured in this area, based on observed and simulated water 

levels in this area for the middle Potomac-RaritanMagothy aquifer (A2), simulated water levels probably 

are 15 to 20 feet lower than actual water levels. Another 

poorly simulated area is in Salem County near Delaware 

Bay, where simulated water levels are as much as 20 feet 

higher than measured water levels. Simulated lateral 

hydraulic gradients are from Delaware toward Gloucester County, whereas measured water levels indicate 

gradients are downdip toward Cumberland County. The 

reason for this difference is unknown.

Simulated 1978 water levels for the Englishtown aquifer (A4) closely match the interpreted 1978 potentiometric surface in the northern part of the aquifer (fig. 45). 

Although some simulated water levels (wells 25^429 and 

29-534, table 15) near the very steep cone of depression 

in Ocean and Monmouth Counties are about 40 feet 

higher than measured water levels, the area is simulated 

as closely as possible with the cell size used in that area. 

Measured 1978 water levels for the Englishtown aquifer 

in central Camden County as shown by Walker (1983, 

pi. 3) were incorrect, and 1983 measured water levels are 

about 40 feet above sea level (Eckel and Walker, 1986, 

pi. 4). Therefore, the simulated water levels of 60 feet 

(fig. 45) are probably 20 feet too high. A local groundwater low near the Burlington-Monmouth County line is 

not simulated, although the simulated water levels are 

acceptable in this area.

Major features in the 1978 flow system of the 

Wenonah-Mount Laurel aquifer (A5) are similar to those 

in the Englishtown aquifer (A4). The high ground-water 

levels along most of the outcrop, the ground-water low 

near the outcrop in central Burlington County, and the 

large cone of depression centered along the coast of 

Monmouth and Ocean Counties are simulated (fig. 46). A 

local ground-water low in western Monmouth and Ocean 

Counties is not simulated, probably because of the cell 

size in the area. With no water-level data available in 

downdip areas, the accuracy of the simulated water 

levels in this area could not be evaluated.

Simulated water levels in the Vincentown aquifer (A6) 

were not calibrated because there is only one observation 

well at which measured and simulated water levels can 

be compared. Simulated water levels are about 12 feet 

lower than measured water levels at the observationwell site in western Ocean County (well 29-139, table 

15). The simulated 1978 potentiometric surface is consistent with the conceptual model and the simulated water 

levels in adjacent aquifers. Simulated water levels for 

the Vincentown aquifer (A6) are shown in figure 47. 

The configuration of simulated potentiometric surface 

for the Vincentown aquifer is similar to the simulated
SIMULATION OF GROUND-WATER FLOW H65

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PENNSYLVANIA FALL LINE - '

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75°

EXPLANATION

 .' : ' ' . . .' ; : OUTCROP AREA OF THE VINCENTOWN FORMATION IN NEW JERSEY

74°

40°

10 15 MILES

j____I

0 5 10 15 KILOMETERS

-40-

29-139 

(130)

SIMULATED POTENTIOMETRIC CONTOUR Shows altitude of simulated 

prepumping potentiometric surface January 1, 1978. Contour interval 10 and 

20 feet. National Geodetic Vertical Datum of 1929

OBSERVATION WELL AND WELL NUMBER Altitude of measured 

water level, in feet above or below National Geodetic Vertical Datum of 1929 

is in parentheses. Date of measurement is closest measurement date to 

January 1, 1978. From Zapecza, Voronin, and Martin (1987, pi. 7). Simulated 

and measured water levels given in table 15

,© d

hH ^

HH

H

hH

Oo o

74° 39°

FIGURE 47. Simulated 1978 potentiometric surface for the Vincentown aquifer (model unit AS).
40° 75°

39°

SALEM ^ GLOUCESTER JCAMDEN

/

v

ATLANT.C

75°

74°

40°

5 10 15 MILES

j____i____i

0 5 10 15 KILOMETERS

EXPLANATION

- 40 SIMULATED POTENTIOMETRIC CONTOUR Shows altitude of simulated

prepumping potentiometric surface January 1, 1978. Contour interval variable. 

National Geodetic Vertical Datum of 1929

OBSERVATION WELL AND WELL NUMBER Altitude of measured 

11-44 water level, in feet above or below National Geodetic Vertical Datum of 1929, 

' 1 &) is in parentheses. Date of measurement is closest measurement date to

January 1, 1978. From Zapecza, Voronin, and Martin (1987, pi. 7). Simulated and measured water levels given in table 15

o 2

o

74° 39°

FIGURE 48. Simulated 1978 potentiometric surface and measured 1978 water levels for the Piney Point aquifer (model unit A7).
H72 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

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SIMULATION OF GROUND-WATER FLOW H73

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H74 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

74r 45'

39' 15'

EXPLANATION ^-"^l/v^ 

-10 SIMULATED WATER-TABLE CONTOUR Shows altitude of

simulated water table January 1, 1978. Contour interval 5 feet. 

National Geodetic Vertical Datum of 1929

' OBSERVATION WELL AND WELL NUMBER Altitude of measured 

9-20 water level, in feet above or below National Geodetic Vertical Datum 

(5) of 1929, is in parentheses. Date of measurement is

closest measurement date to January 1, 1978. From Zapecza, 

Voronm, and Martin (1987, pi. 7). Simulated and measured 

water levels given in table 15

7 CAPE MAY COUNTY

DELAWARE 

BAY

' 9-26 

9-20 ' (5) 

(5) \ _ __G

Cape May

4 MILES

4 KILOMETERS

Base from U.S. Department of Agriculture, 

Soil Conservation Service, 1:250,000,1980

FIGURE 51. Simulated 1978 water table and measured 1978 water levels for the Holly Beach aquifer

(model unit A10).

potentiometric surface for the underlying WenonahMount Laurel aquifer (A5), and the potentiometric surface reflects land-surface altitudes near the Vincentown 

outcrop area.

The simulated 1978 potentiometric surface and measured 1978 water levels for the Piney Point aquifer (A7) 

are shown in figure 48. As with the Vincentown aquifer 

(A6), there are not enough observation wells to draw an 

interpreted potentiometric surface for the Piney Point 

aquifer. However, there are enough observation wells to

determine that the simulated water levels are within 

reasonable ranges. Simulated water levels for six of the 

seven observation wells are within about 10 feet of the 

measured water levels (table 15). The flow system within 

the Piney Point aquifer consists of high ground-water 

levels along the county line between central Burlington 

and Ocean Counties, low ground-water altitudes beneath 

the Atlantic Ocean and Delaware Bay, and a small cone 

of depression along the coast in Ocean County. Groundwater levels in western Cumberland County are simu-
SIMULATION OF GROUND-WATER FLOW H75

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UPPER POTOMAC-RARITAN-MAG 

WELL 33-187 NOD 

LOCATION SHOWN IN F

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OTHY AQUIFER (A3) 

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I 1 1 1 I I, MIDDLE POTOMAC-RARITAN-MAGOTHY AQUIFER (A2) 

WELL 15-97 NODES, 18 

LOCATION SHOWN IN FIGURE 43

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WELL 7-283 NODE 5, 22

LOCATION SHOWN IN FIGURE 42

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1958 1965 1968 1973 1978 1981

^ C w ^ C ^ ^ 1 ^ ^ O ^ ^ O i^

PUMPING PERIOD 

FIGURE 52. Hydrographs of simulated and measured water levels for the Potomac-Raritan-Magothy aquifers (model units Al, A2, and A3).

lated about 15 feet too high, as shown in table 15 for well 

11-96. Ground-water withdrawals in Delaware have 

caused a large cone of depression in the Piney Point 

aquifer and actual water levels along the shore of Cumberland County were probably about 20 feet below sea 

level in 1981. Measured 1983 water levels (Eckel and 

Walker, 1986, pi. 6) indicate that another small cone of 

depression near Barnegat Light in Ocean County, which 

was not indicated in the 1978 measured water levels, was 

not simulated.

Simulated and interpreted potentiometric surfaces and 

measured water levels for the lower Kirkwood-Cohansey 

aquifer and the confined Kirkwood aquifer (A8) are 

shown in figure 49. Simulated and measured hydrographs for this model unit are shown in figure 54. The

simulated and interpreted 1978 potentiometric surfaces 

(fig. 49) for the confined Kirkwood aquifer match closely. 

The simulated cone of depression at Atlantic City is 

slightly deeper than the measured cone, but the 

simulated potentiometric surface along the coast to the 

northeast is slightly higher than the interpreted potentiometric surface. Comparison of simulated and measured hydrographs for several wells near Atlantic City 

(wells 1-37, 1-180, and 1-366 in table 15) shows that, 

although simulated water levels near the end of the 

simulation match measured water levels fairly well, the 

trend of water-level decline is not simulated closely. The 

poorly simulated trends of water-level decline near 

Atlantic City are probably the result of poor estimates of 

pumpage prior to 1970.
H76 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

0 

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-120

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ENGLISHTOWN AQUI 

WELL 25-429 NODE 

LOCATION SHOWN INF

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ENGLISHTOWN AQUIF 

WELL 29-138 NODE 

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WENONAH-MOUNT LAUREL 

WELL 7-478 NODE 

LOCATION SHOWN IN F

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AQUIFER (A5) 

10,20 

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1958 1965 1968 1973 1978

PUMPING PERIOD

FIGURE 53. Hydrographs of simulated and measured water levels for the Englishtown and Wenonah-Mount Laurel aquifers (model units A4

and A5).

Simulated water levels in offshore areas of the confined Kirkwood aquifer (model unit A8) near Atlantic 

City have been verified by water levels in two observation wells drilled in 1985, after calibration of the model. 

Water levels measured on January 2, 1986, were 72 feet 

below sea level in well 1-710 approximately 2 miles 

offshore and 59 feet below sea level in well 1-711 

approximately 5 miles offshore, (J.S. Clark, written 

commun., 1987). Simulated water levels for January 1, 

1986, were obtained by extending the period of simulation using the calibrated model. Withdrawals for 1981 

through 1983 were estimated on the basis of data in the 

Ground-Water Withdrawal Inventory data base of the 

New Jersey District of the U.S. Geological Survey.

Withdrawal data for 1984 and 1985 were estimated on the 

basis of historic withdrawal trends (W.A. Battaglin and 

M.C. Hill, written commun., 1987). Simulated water 

levels for January 1, 1986, were within 5 feet of the 

measured water level for each well. The similarity 

between the simulated and measured water levels demonstrates the ability of the regional model to aid in the 

definition and evaluation of the flow system.

Simulated and measured water levels in the lower part 

of the unconfined Kirkwood-Cohansey aquifer (A8) 

match closely. Measured 1978 water levels in the unconfined areas are essentially the same as the prepumping 

water levels for this area and are within a few feet of the 

water table in the unconfined upper Kirkwood-Cohansey
SIMULATION OF GROUND-WATER FLOW H77

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UPPER KIRKWOOD-COHANSEY AQUIFER (A9)

WELL 9-48 NODE 23, 7

LOCATION SHOWN IN FIGURE 50 inn o/\ i V IT '< /" \ /

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PUMPING PERIOD

FIGURE 54. Hydrographs of simulated and measured water levels for the confined Kirkwood aquifer and upper Kirkwood-Cohansey aquifer

(model units A8 and A9).

aquifer (A9). Simulated and measured hydrographs for 

this area show no large long-term decline in water levels 

as the result of pumping. However, measured hydrographs show water-level fluctuations that are the result 

of seasonal and drought conditions (Zapecza, Voronin, 

and Martin, 1987, pi. 9 and p. 10). These short-term 

fluctuations are not simulated because recharge was not 

varied over the simulated time period.

Water levels in the upper Kirkwood-Cohansey aquifer 

(A9) are also simulated closely (fig. 50). Most of this 

aquifer system is unconfined, and simulated 1978 water 

levels are nearly the same as simulated prepumping 

water levels. Measured water levels (Zapecza, Voronin, 

and Martin, 1987, pi. 9) show short-term fluctuations 

that are not simulated (well 9^18, fig. 54) because they

are not caused by long-term pumping. Simulated and 

measured water levels show a small cone of depression in 

Cape May County, the only confined part of the upper 

Kirkwood-Cohansey aquifer (A9). Although the shape 

and location of this cone are not simulated exactly, the 

general trend of the ground-water levels is simulated.

Generally, the 1978 water levels in the Holly Beach 

aquifer (A10) are assumed to be similar to prepumping 

water levels because the entire aquifer is unconfined and 

withdrawals are relatively small. Several measured 

water levels are shown with the simulated potentiometric surface for the Holly Beach aquifer in figure 51. 

Neither the measured (Zapecza, Voronin, and Martin, 

1987, pi. 10) nor the simulated water levels (table 15) 

show any long-term decline from pumping.
H78 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

Simulated flow between the water table and streams in 

1978 is considered comparable to the recharge and discharge areas postulated in the conceptual model and to 

the simulated prepumping flow system. Generally, 1978 

flow to streams is similar to flow during prepumping 

conditions (fig. 41), except in the outcrop area of the 

three Potomac-Raritan-Magothy aquifers (Al, A2, and 

A3). In most areas, change in flow to streams decreased 

less than 5 in/yr. The average flow to streams decreased 

between 2.5 and 3.0 in/yr. However, along the PotomacRaritan-Magothy outcrop area locally in Middlesex 

County and near the Delaware River in Gloucester, 

Camden, and Burlington Counties, flow to streams 

decreased 10 to 50 in/yr. These extreme changes in flow 

are in unconfined parts of the Potomac-Raritan-Magothy 

aquifers where withdrawals exceed 13 Mgal/d per node. 

Simulated reductions in streamflow that are greater than 

the sum of simulated prepumping discharge and the 

applied recharge rate of 20 in/yr are possible in the model 

because the constant-head nodes representing stream 

stages are able to supply an infinite source of water. In 

areas where simulated transient flow is out of these 

stream nodes, the model poorly represents recharge and 

the flow between streams and the water table. Simulated 

flow from three constant-head stream nodes (3, 23; 3, 24; 

and 4, 42) for January 1, 1978, is greater than 10 in/yr. 

This may indicate a critical reduction in streamflow or 

that the actual increase in recharge to the water table 

and the corresponding decrease in streamflow occur as 

smaller rates over larger areas than those simulated by 

the model.

EVALUATION OF HYDRAULIC CHARACTERISTICS AND 

FLOW SYSTEM BASED ON SIMULATION

Data values of aquifer and confining-unit hydraulic 

characteristics derived from the calibrated model are 

estimates of these properties on a regional scale. The 

water-transmitting character of the aquifers and confining units is shown by maps of aquifer transmissivity and 

confining-unit vertical leakance. These transmitting 

characteristics are lumped coefficients that are dependent on the hydraulic conductivity and thickness of the 

units. Aquifer hydraulic conductivity can be estimated 

by dividing transmissivity by saturated aquifer thickness. Vertical hydraulic conductivity of the confining 

units can be estimated by multiplying the vertical leakance by the unit's thickness.

Flow rates between aquifers have been computed by 

using simulated water levels and confining-unit vertical 

leakance values from the calibrated model. Flow rates 

between aquifers are shown by maps of flow to and from 

an aquifer through the overlying confining unit. Flow 

rates into an aquifer are positive; flow rates out of an

aquifer are negative. Therefore, because flow rates are 

taken through the overlying confining unit, positive flow 

rates represent downward flow, and negative rates 

represent upward flow. These flow rates are regional 

estimates of recharge to and discharge from the aquifers. 

The model estimates of transmissivity, vertical leakance, and flow rates may not be representative for local 

areas that are smaller than the model cell areas. The 

accuracy of calibrated model data and data results is 

dependent on (1) the accuracy of the conceptual model; 

(2) the cell size; (3) the assumed boundary conditions; (4) 

the amount and distribution of data on water levels, 

withdrawals, and aquifer and confining-unit properties; 

and (5) the accuracy of the model calibration. Hydraulic 

characteristics used in the calibrated model are generally 

similar, but not identical, to estimates derived from 

previous simulation studies or field measurements.

TRANSMISSIVITY

Transmissivity used in the calibrated model for each 

aquifer is shown in figures 55 through 64. The range of 

estimated transmissivity from the calibrated model is 

given in table 8 for each aquifer. Comparison of the 

model-calibrated transmissivity (table 8) to the initial 

estimates of transmissivity, based on specific-capacity 

and aquifer-test data shown in table 5, shows that the 

maximum transmissivity for each unit in the model is 

about 20 to 40 percent lower in five aquifers, 55 percent 

lower in one aquifer, 6 percent higher in one aquifer, and 

unchanged in three aquifers.

The transmissivity shown in figures 55 through 64 is a 

regional estimate for the entire modeled extent of each 

aquifer. In outcrop areas, the transmissivity does not 

represent actual unconfined transmissivity. Actual 

transmissivity in the unconfined outcrop areas decreases 

with declining water levels. Most nodes simulating the 

aquifer outcrop areas also represent confined parts of the 

aquifers because of the large grid spacing. The unconfined parts of the upper Kirkwood-Cohansey aquifer (A9) 

and the Holly Beach aquifer (A10), like the outcrop 

areas, are simulated as confined aquifers beneath the 

confining streambeds and modeled transmissivity does 

not change with declining water levels. In these unconfined areas where withdrawals have caused water-level 

declines, hydraulic conductivity estimates, based on 

transmissivity and saturated thickness used in this 

model, are probably too low.

The transmissivity of the lower Potomac-RaritanMagothy aquifer (Al) is shown in figure 55 and ranges 

from 860 to 10,400 ft2/d (table 8). The low values are in 

areas where the aquifer thins beneath the Delaware 

River. The highest transmissivity is updip in northern 

Camden and Gloucester Counties and downdip in Ocean 

County. For most of the aquifer's extent, transmissivity
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FIGURE 55. Transmissivity used in the model for the lower Potomac-Raritan-Magothy aquifer (model unit Al).

a
H80 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

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APPROXIMATE SEAWARD LIMIT OF FRESHWATER IN THE 

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FIGURE 57. Transmissivity used in the model for the upper Potomac-Raritan-Magothy aquifer (model unit A3).

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H82 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

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H84 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

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H86 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

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74° 45'

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39° 15'

 5 000- LINE OF EQUAL TRANSMISSIVITY Interval 

500 feet squared per day

CAPE MAY COUNTY

-5,500

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FIGURE 64. Transmissivity used in the model for the Holly Beach Aquifer (model unit A10).

is between 5,200 ft2/d and 10,400 ft2/d. Lateral variability 

of transmissivity in the lower aquifer reflects changes in 

aquifer hydraulic conductivity more than changes in 

aquifer thickness.

Transmissivity of the middle Potomac-RaritanMagothy aquifer (A2) is shown in figure 56 and ranges 

from 600 to 23,000 ft2/d (table 8). The highest transmissivity is in northern Ocean and southern Monmouth 

Counties; the lowest transmissivity is near the outcrop 

where the aquifer thins and also in downdip areas.

Transmissivity estimates are relatively high, 11,000 

ft2/d, in northern Camden County. Lateral changes in 

transmissivity in the middle aquifer reflect changes in 

hydraulic conductivity and do not reflect changes in 

aquifer thickness. These transmissivity values are generally 30 percent and locally 50 percent, less than those 

used by Farlekas (1979, p. 31) to simulate flow in the 

Farrington aquifer in Middlesex and Monmouth Counties. The differences in local transmissivity are probably 

the result of the smaller grid spacing used by Farlekas
SIMULATION OF GROUND-WATER FLOW H89

TABLE 8. Range of transmissivity and confining-unit vertical 

leakance used in the calibrated model

Model 

unit

Al

A2

A3

A4

A5

A6

A7

A8

A9

A10

Aquifer

Lower Potomac-Raritan-Magothy

Middle Potomac-Raritan-Magothy

Upper Potomac-Raritan-Magothy

Englishtown

Wenonah-Mount Laurel

Vincentown

Piney Point

Lower Kirkwood-Cohansey

and confined Kirkwood.

Upper Kirkwood-Cohansey

Holly Beach

Transmissivity 

(feet squared 

per day)

860-10,400

600-23,000

300-12,100

70- 4,400

60- 1,400

860- 3,500

170- 5,200

860-10,000

860-13,000

270-11,700

5,200- 7,800

Model

unit Confining unit

Vertical

leakance

(foot per day

per foot)

Cl Between the lower and middle

Potomac-Raritan-Magothy aquifers.

C2 Between the middle and upper

Potomac-Raritan-Magothy aquifers.

C3 Merchantville-Woodbury

C4 Marshalltown-Wenonah

C5 Navesink-Hornerstown

C6 Vincentown-Manasquan

C7 Basal Kirkwood

C8 Overlying the Rio Grande waterbearing zone.

C9 Estuarine clay

2xlO~6-4xlO~ 

3xlO~8-5xlO-3

2xlO~8-5xlO~ x

3xlO~8-lxlO~6 

2xlO" 7-5xlO-1

(1979), and regional differences are probably the result of 

differences in definition of the middle aquifer and different boundary conditions.

Transmissivity of the upper Potomac-RaritanMagothy aquifer (A3) is shown in figure 57 and ranges 

from 300 to 12,100 ft2/d (table 8). The lowest transmissivity is beneath the Delaware River in northern Salem 

County. Relatively low transmissivity, less than 3,000 

ft2/d, is in areas near the outcrop where the aquifer thins 

and in downdip areas in Cumberland, Atlantic, Cape 

May, southern Burlington, and southern Ocean Counties. The highest transmissivity is offshore of Monmouth 

County. Relatively high transmissivity, greater than 

10,000 ft2/d, is along the shore of Monmouth County, in 

northern Camden, northern Gloucester, and eastern 

Monmouth Counties. Unlike the lower and middle 

Potomac-Raritan-Magothy aquifers (Al and A2), lateral 

changes in transmissivity of the upper aquifer are partly 

related to changes in aquifer thickness. The thickest part 

of the aquifer, near the shore of Monmouth County, also 

has the highest transmissivity.

Transmissivity of the Englishtown aquifer (A4) is 

shown in figure 58 and ranges from 70 to 4,400 ft2/d (table 

8). The highest transmissivity is in Monmouth County, 

where the aquifer is thickest. The lowest transmissivity

is in updip and downdip areas where the aquifer thins 

near its limit. In general, lateral changes in transmissivity reflect changes in aquifer thickness. Transmissivity 

shown in figure 58 for Ocean and Burlington Counties is 

generally similar to that used by Nichols (1977a, p. 26) to 

simulate flow in the Englishtown aquifer. However, in 

northeastern Monmouth County, transmissivity is about 

two times higher than that used by Nichols (1977a, 

p. 26).

Transmissivity of the Wenonah-Mount Laurel aquifer 

(A5), shown in figure 59, ranges from 60 to 1,400 ft2/d 

(table 8) and is generally lower than all the other Coastal 

Plain aquifers. There is little lateral variability, and 

1,000 ft2/d is a representative average for the aquifer. 

Calibrated transmissivity estimates fall approximately 

within the range of transmissivity estimated by Nemickas (1976, p. 39). Lateral changes in transmissivity 

generally result from changes in aquifer thickness, and 

the highest transmissivity is in Salem, central Camden, 

and central Burlington Counties, where the aquifer is 

thickest.

Transmissivity of the Vincentown aquifer (A6) is 

shown in figure 60 and ranges from 860 to 3,500 ft2/d 

(table 8). Lateral changes in transmissivity result from 

changes in aquifer thickness. Highest transmissivity 

values are very localized in Salem and Monmouth Counties. Lowest transmissivity is in Gloucester and northern 

Salem Counties. Final transmissivity estimates used in 

the model are the same as the initial estimates based on 

an average hydraulic conductivity (table 5).

Transmissivity of the Piney Point aquifer (A7) is 

shown in figure 61 and ranges from 170 to 5,200 ft2/d 

(table 8). The areas of transmissivity greater than 2,000 

ft2/d are mostly in Burlington, Ocean, Cumberland, and 

Cape May Counties where the aquifer is thickest. Transmissivity is relatively low, less than 1,000 ft2/d, in 

Atlantic, southern Camden, and southern Gloucester 

Counties.

Transmissivity of the confined Kirkwood aquifer (the 

downdip part of A8) is shown in figure 62 and ranges 

from about 860 to 13,000 ft2/d (table 8). Generally, transmissivity is about 5,000 to 6,000 ft2/d with 

local areas of higher transmissivity. Areas of highest 

transmissivity, greater than 10,000 ft2/d, are along the 

coast southwest of Atlantic City. Low transmissivities, 

less than 4,000 ft2/d, are along the updip limit of the 

confined Kirkwood aquifer. Although there are no data 

to suggest either low hydraulic conductivity or that the 

unit is relatively thin in this area, low transmissivity was 

needed to simulate the cone of depression at Atlantic 

City. Water levels along the coast were simulated by 

decreasing the amount of flow from the updip unconfined 

part of model unit A8 by decreasing transmissivity. 

Decreasing flow through the overlying confining unit C8
H90 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

by decreasing vertical leakance did not improve the 

calibration. The lower parts of the unconfined KirkwoodCohansey aquifer and the confined Kirkwood aquifer are 

assumed to be part of the same model unit (A8) and have 

a direct lateral hydraulic connection. However, more 

geohydrologic and geophysical data are needed to refine 

the aquifer characteristics in this area.

Transmissivity of the lower Kirkwood-Cohansey aquifer, the updip part of model unit A8, is shown in figure 62 

and ranges from 860 to 10,000 ft2/d (table 8). Transmissivity is lowest (less than 4,000 ft2/d) where the aquifer 

thins near its outcrop area. Downdip, transmissivity is 

generally greater than 7,000 ft2/d. The highest transmissivity (greater than 10,000 ft2/d) is in central Burlington 

and central Ocean Counties.

Transmissivity of the upper Kirkwood-Cohansey aquifer (A9) is shown in figure 63 and ranges from 270 to 

11,700 ft2/d (table 8). Transmissivity is lowest (less than 

6,000 ft2/d) in updip areas where the aquifer thins. 

Highest transmissivity (greater than 10,000 ft2/d) is 

along the coast in Cape May, Atlantic, and southern 

Ocean Counties. The confined part of the upper 

Kirkwood-Cohansey aquifer in southern Cape May 

County has transmissivity ranging from 8,000 to 11,700 

ft2/d. Transmissivity for the unconfined KirkwoodCohansey aquifer system, represented by the combined 

lower and upper Kirkwood-Cohansey aquifers (A8 and 

A9) in the model, is highest (about 14,000 to 18,000 ft2/d) 

where the aquifer system is thickest in central Cumberland, northern Atlantic, central Burlington, and central 

Ocean Counties.

Transmissivity of the Holly Beach aquifer (A10) is 

shown in figure 64 and ranges from 5,200 ft2/d to 7,800 

ft2/d (table 8). Final estimates of transmissivity are the 

same as the initial estimates based on hydraulic conductivities determined from specific-capacity tests (table 5).

VERTICAL LEAKANCE OF CONFINING UNITS

Vertical leakance used in the calibrated model for each 

of the confining units is shown in figures 65 to 73 and 

summarized in table 8. Leakance, when multiplied by 

confining-unit thicknesses, gives the vertical hydraulic 

conductivity of the unit. The vertical hydraulic conductivity of the confining units is of the same order of 

magnitude reported by Luzier (1980, p. 29), Nemickas 

(1976, p. 37), Nichols (1977a, p. 76), and Farlekas (1979, 

p. 36); however, the lateral distribution is somewhat 

different from that reported by those investigators.

Lateral variability of vertical leakance reflects variability in vertical hydraulic conductivity and confiningunit thickness. Highest leakance is in updip areas, at and 

near the outcrops, where confining units are thinnest. In 

other areas, however, lateral changes in vertical hydraulic conductivity, which varies several orders of magnitude within a confining unit, tend to minimize the effects 

on leakance by changes in thickness, which varies about 

one order of magnitude.

Generally, leakance varies laterally in the updip areas 

of the confining units. Lateral changes in leakance in 

updip areas are local, whereas lateral changes in downdip 

areas are over large areas. Although the leakance values 

shown in figures 65 to 73 represent the regional transmitting properties of the confining units, the simulated 

lateral variability of leakance within the units is affected 

by the distribution of measured water levels used in 

calibration and by model sensitivity to leakance. Measured water levels are more abundant in shallow updip 

areas, and calibration on a more local scale is possible. In 

downdip areas, measured water levels are fewer and 

only a more regional calibration is possible. Also, simulated water levels in downdip areas are much less 

sensitive to local changes in leakance. Therefore, leakance distributions with high variability in downdip areas 

were not considered during the calibration process. 

Although the regional vertical leakance of the confining 

units has been adequately simulated, the leakance values 

may not be locally representative in downdip areas.

The Merchantville-Woodbury confining unit (C3) and 

the Vincentown-Manasquan confining unit (C6) have 

relatively low leakance values, less than lxlO~8 feet per 

day per foot ((ft/d)/ft), nearshore and offshore of southern Monmouth and northern Ocean Counties (figs. 67 

and 70). Downdip areas of most of the confining units 

have leakances of about lxlO~8 to lxlO~6 (ft/d)/ft. 

The Merchantville-Woodbury, Marshalltown-Wenonah, 

Navesink-Hornerstown, and Vincentown-Manasquan 

confining units (C3, C4, C5, and C6) have leakances 

in downdip areas to the northeast that are at least an 

order of magnitude lower than leakances in downdip 

areas to the southwest (figs. 67-70). However, the basal 

Kirkwood confining unit (C7) has leakances in downdip 

areas to the northeast that are at least an order of 

magnitude higher than leakances in downdip areas to the 

southwest (fig. 71). The confining unit between the lower 

and middle Potomac-Raritan-Magothy aquifers (Cl) and 

the Marshalltown-Wenonah confining unit (C4) have 

relatively high leakances in some downdip areas compared to other confining units. The confining unit 

between the lower and middle Potomac-RaritanMagothy aquifers (Cl) has leakance between lx 10~6 and 

lxlO~4 (ft/d)/ft throughout most of its downdip extent 

(fig. 65). The high leakance is consistent with the hydrogeologic framework described by Zapecza (1984, p. 12). 

He states that the lower and middle aquifers of the 

Potomac-Raritan-Magothy aquifer system are largely 

interbedded sands, silts, and clays in downdip areas and 

cannot be distinguished from each other. High leakance
SIMULATION OF GROUND-WATER FLOW H91

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74° 39° Location of 10,000 milligrams per liter chloride concentrations based on Meisler (1981, fig. 4). 

FIGURE 66. Vertical leakance used in the model for the confining unit between the middle and upper Potomac-Raritan-Magothy aquifers (model unit C2).

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SIMULATION OF GROUND-WATER FLOW H93
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BY CHLORIDE CONCENTRATIONS OF 10,000 MILLIGRAMS PER LITER

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FIGURE 68. Vertical leakance used in the model for the Marshalltown-Wenonah confining unit (model unit C4).
SIMULATION OF GROUND-WATER FLOW H95

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FIGURE 70. Vertical leakance used in the model for the Vincentown-Manasquan confining unit (model unit C6).
SIMULATION OF GROUND-WATER FLOW H97

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PENNSYLVANIA FALL LINE -"'

75°

0 5 10 15 MILES

i i i____i

0 5 10 15 KILOMETERS

EXPLANATION

5 x 70- 7 LINE OF EQUAL LEAKANCE Interval, in feet per day 

per foot, is variable

74°

40°

ffi

CD 00H 

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co

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74° 39°

FIGURE 72. Vertical leakance used in the model for the confining unit overlying the Rio Grande water-bearing zone (model unit C8).
40° 75°

39°

75°

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5 x 10~ - 

EXPLANATION

 . > 5x70-7 LINE OF EQUAL LEAKANCE Interval, in feet per day 

0 5 10 15 MILES / per foot, is variable

0 5 10 15 KILOMETERS ^

74°

CO

gps

>TJ

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40° £

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74° 39°

FIGURE 73. Vertical leakance used in the model for the estuarine clay confining unit (model unit C9).
H100 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

between the lower and middle aquifers causes them to 

respond to stresses as one hydrologic unit. The 

Marshalltown-Wenonah confining unit (C4) has leakance 

between 1 x 1(T6 and 1 x 1(T4 (ft/d)/ft in downdip areas in 

Cape May, southeastern Atlantic, and southeastern 

Cumberland Counties (fig. 68).

In updip areas where the confining units are relatively 

thin, leakance ranges between lxl(T5 and lxl(T8 

(ft/d)/ft. The highest leakance, greater than lxl(T4 

(ft/d)/ft, is along the updip limit of the confining units 

among the Potomac-Raritan-Magothy aquifers (Cl and 

C2) and the Navesink-Hornerstown confining unit (C5). 

Another area of high leakance is where the model 

framework was adjusted to include an extension of the 

Merchantville-Woodbury confining unit (C3) over the 

modeled outcrop area of the upper Potomac-RaritanMagothy aquifer (A3) (fig. 67). Leakance in this area is as 

high as 5xlO~3 (ft/d)/ft. This extension of the confining 

unit was necessary to simulate water-level declines near 

the outcrop area of the upper Potomac-Raritan-Magothy 

aquifer near the Delaware River. This approach was 

probably necessary because of the large block size used 

to represent the relatively narrow outcrop area.

The onshore unconfined parts of the aquifers are 

overlain by an artificial confining unit representing an 

effective streambed leakance in the 11-layer steady-state 

and transient models. Flow between the constant-head 

boundary (representing the stream stages) and the 

water table is dependent on the leakance of this streambed confining unit. Streambed leakance values are calculated for each node from the long-term areally averaged 

stream stages, the simulated water-table altitude, the 

assumed recharge rate, and the simulated deep percolation (fig. 25). These leakances do not represent the 

hydraulic properties of actual streambed sediments and 

are not shown in figures 65 through 73. However, they 

do represent the regional connection between the watertable aquifer and streams. Streambed leakances range 

from 6xlO~6 to 1.5XKT1 (ft/d)/ft and are generally the 

highest leakances (table 8) for each confining unit.

Areas where confining units are absent between aquifers are relatively small except between the lower and 

upper Kirkwood-Cohansey aquifers (A8 and A9 in updip 

areas). In areas where confining units are absent 

between aquifers over several nodes, artificial confiningunit thicknesses of about 0.1 foot were used to give very 

high leakance values to simulate the direct hydrologic 

connection between overlying and underlying aquifers. 

These leakance values (not shown in figures 65 to 73) are 

several orders of magnitude greater than the confiningunit leakance values. Vertical leakance between the 

upper and lower Kirkwood-Cohansey aquifers was calculated as the harmonic mean of the leakance of the 

adjacent aquifers. The vertical hydraulic conductivity of

the aquifers was estimated to be 0.01 times the aquifers' 

horizontal hydraulic conductivity. The resulting vertical 

leakance between the lower and upper KirkwoodCohansey aquifers is about 5xlO~2 to IxlO" 1 (ft/d)/ft.

AQUIFER STORAGE

The model was calibrated by using a storage coefficient 

of 0.15 in unconfined areas. A storage coefficient of 

IxlO"4 was used for all confined aquifers except in 

downdip areas of the three Potomac-Raritan-Magothy 

aquifers (Al, A2, and A3) in Monmouth and Ocean 

Counties, where storage coefficients of 5xlO~4 to 

8xlO~4 were used. The higher storage coefficient in the 

Potomac-Raritan-Magothy aquifers represents storage 

properties in areas where the aquifers are relatively 

thick. These higher values were used because simulated 

water levels in this area did not change significantly 

during calibration as a result of changing estimates of 

aquifer transmissivity and confining unit leakance within 

a reasonable range. Water levels were calibrated in this 

area by increasing aquifer storage of the three PotomacRaritan-Magothy aquifers to five to eight times the 

original estimate of IxlO"4, which was unchanged 

everywhere else in the modeled area.

PREPUMPING STEADY-STATE FLOW SYSTEM

In the simulated prepumping flow system, groundwTater recharge occurs in areas where the land surface is 

higher than adjacent areas. These areas can be seen as 

unshaded areas in figure 41 in the southeastern parts of 

Salem, Gloucester, Camden, Burlington, Mercer, and 

Middlesex Counties; the western parts of Ocean and 

Monmouth Counties; and in central Cumberland, Cape 

May, and Atlantic Counties. Regional discharge areas in 

the prepumping flowT system are shaded in figure 41 and 

include the Atlantic Ocean, Delaware River, Delaware 

Bay, Raritan Bay, and relatively large rivers in the 

Coastal Plain. These rivers include the Cohansey and 

Maurice Rivers in Cumberland County, the Great Egg 

Harbor River in Atlantic County, the Batsto and Mullica 

Rivers in Atlantic and Burlington Counties, the Toms 

River in Ocean County, and the Manasquan and Navesink Rivers in Monmouth County.

Simulated vertical flow in two cross sections of the 

Coastal Plain aquifers is shown in figure 74 for prepumping conditions. Simulated vertical hydraulic gradients 

between aquifers are highly variable but tend to be 

greater in updip than in dowTndip areas. Similarly, simulated vertical ground-wTater flowT rates are also higher in 

updip areas (0 to 4 in/yr) than rates in downdip areas (0 

to 0.2 in/yr). The prepumping flow system is described 

below for each aquifer.
SIMULATION OF GROUND-WATER FLOW H101

B . _^\ --Wi

>J \ / \

r-- \ : v Y ,. "x v\. i ;-:/ ^

i ^K .\ ^

--K V\

,^--__^d:

'* J r«M-jT

'>.' 

/ eDELAWARF

e/\v

0 10 20 30 MILES

0 10 20 30 KILOMETERS

NORTHWEST 

Fall Line

EXPLANATION

n AQUIFER 

CONFINING UNIT

GENERALIZED DIRECTION 

OF GROUND-WATER 

FLOW

HYDROGEOLOGIC UNIT

A10 Holly Beach aquifer

C9 Estuarine clay confining unit

A9 Upper Kirkwood-Cohansey aquifer

C8 Confining unit overlying the Rio Grande water-bearing zone

A8 Lower Kirkwood-Cohansey aquifer and confined Kirkwood aquifer

C7 Basal Kirkwood confining unit

A7 Piney Point aquifer

C6 Vincentown-Manasquan confining unit

A6 Vincentown aquifer

C5 Navesink-Hornerstown confining unit

A5 Wenonah-Mount Laurel aquifer

C4 Marshalltown-Wenonah confining unit

A4 Englishtown aquifer

C3 Merchantville-Woodbury confining unit

A3 Upper Potomac-Raritan-Magothy aquifer

C2 Confining unit between the middle and upper Potomac-Raritan-Magothy aquifers

A2 Middle Potomac-Raritan-Magothy aquifer

C1 Confining unit between the lower and middle Potomac-Raritan-Magothy aquifers

A1 Lower Potomac-Raritan-Magothy aquifer Not to scale

/ \ 

A1 C1

NORTHWEST A4 

Fall Line

Idealized interface where ground water 

contains 10,000 milligrams per liter 

chloride concentrations

FIGURE 74. Simulated prepumping flow in two hydrogeologic sections of the Coastal Plain.
H102 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

Simulated prepumping water levels for the three 

Potomac-Raritan-Magothy aquifers (Al, A2, and A3) are 

within 10 feet of each other at all locations. Under 

prepumping conditions, the flow systems in the three 

aquifers are similar, and the Potomac-Raritan-Magothy 

aquifer system can be considered as a single hydrologic 

unit. Recharge to the aquifers is from the overlying 

Englishtown aquifer (A4) and the outcrop area in Mercer, Middlesex, and Monmouth Counties. Vertical flow 

through the tops of the Potomac-Raritan-Magothy aquifers is shown in figures 75, 76, and 77. Simulated 

prepumping flow is mostly downward from the Englishtown aquifer (A4) to the upper Potomac-RaritanMagothy aquifer (A3) and generally downward into the 

other two Potomac-Raritan-Magothy aquifers. Vertical 

water-level differences between the upper aquifer and 

the Englishtown aquifer are as much as 70 feet in updip 

areas in western Monmouth County and central Camden 

Counties but generally 20 to 40 feet in downdip areas 

(figs. 32 and 33). Areas of upward discharge under 

prepumping conditions for the three Potomac-RaritanMagothy aquifers are along the outcrop areas in Salem, 

Gloucester, Camden, and Burlington Counties; near the 

Delaware River Estuary in western Salem County; at 

Raritan Bay in the middle and upper Potomac-RaritanMagothy aquifers; in downdip offshore areas; and in 

eastern Monmouth and Ocean Counties in the middle 

Potomac-Raritan-Magothy aquifer.

The Englishtown aquifer (A4) receives recharge in the 

simulated prepumping flow system from parts of its 

outcrop area in western Salem, western Gloucester, 

Mercer, Middlesex, and western Monmouth Counties 

and from the overlying Wenonah-Mount Laurel aquifer 

(A5) through the Marshalltown-Wenonah confining unit 

(C4) (fig. 78). A very small amount of upward leakage 

recharges the Englishtown aquifer from the upper 

Potomac-Raritan-Magothy aquifer (A3) offshore of Monmouth and Ocean Counties (fig. 77). Downward leakage 

from the Wenonah-Mount Laurel aquifer occurs over 

most of the Englishtown aquifer, except locally in western Salem County near the Delaware River, northeastern Monmouth County near the outcrop area, and in 

northeastern Ocean County. Upward discharges from 

the Englishtown aquifer to the Wenonah-Mount Laurel 

aquifer are less than 0.5 in/yr, except in northeastern 

Monmouth County where there are moderate leakage 

rates of 0.5 to 1.0 in/yr. Simulated water-level differences between the Englishtown and Wenonah-Mount 

Laurel aquifers for prepumping conditions are as much 

as 20 feet in updip areas of Monmouth County but less 

than 10 feet in downdip areas and updip areas in the 

western Coastal Plain (figs. 33 and 34). These vertical 

water-level differences are much less than those between 

the Englishtown aquifer and underlying upper PotomacRaritan-Magothy aquifer (A3) because the leakance of 

the Merchantville-Woodbury confining unit (C3) below 

the Englishtown aquifer is 1 to 1.5 orders of magnitude 

less than the leakance of the Marshalltown-Wenonah 

confining unit (C4) above the Englishtown aquifer 

(table 8).

In the simulated prepumping flow system, the 

Englishtown aquifer (A4) receives moderate amounts of 

recharge, 0.5 in/yr or more, in the areas of the groundwater highs directly downdip of the outcrop area in 

Monmouth, central Camden, central Gloucester, and 

northeastern Salem Counties (fig. 33). Although some of 

this recharge flows downdip, some recharge flows updip 

toward the outcrop areas. Water flowing updip in Camden County discharges at the outcrop, but water flowing 

updip in Gloucester and Monmouth Counties may 

become downward leakage to the upper PotomacRaritan-Magothy aquifer because the Englishtown aquifer outcrop areas in Gloucester and Monmouth Counties 

are not discharge areas.

The simulated prepumping flow in the WenonahMount Laurel aquifer (A5) (fig. 79) is similar to flow in 

the underlying Englishtown aquifer (A4). Both aquifers 

are principally recharged by downward leakage from 

overlying aquifers. Ground-water highs exist downdip of 

the outcrop areas in central Camden, central Gloucester, 

northeastern Salem, and western Monmouth Counties 

(fig. 34), and local recharge and discharge areas are 

present along the outcrop. Areas with the highest 

recharge rates, greater than 0.5 in/yr, are in areas of 

ground-water highs. The Wenonah-Mount Laurel aquifer has more upward discharge areas than the Englishtown aquifer. Upward leakage from the Wenonah-Mount 

Laurel aquifer is in offshore areas and along the coast. 

Prepumping vertical water-level differences are less 

than 10 feet in updip areas between the Wenonah MountLaurel aquifer (A5) and the overlying Vincentown aquifer (A6) and the lower Kirkwood-Cohansey aquifer (A8) 

(figs. 34, 35, and 37). In downdip areas, vertical waterlevel differences are up to 60 feet between the WenonahMount Laurel aquifer (A5) and the overlying Piney Point 

aquifer (A7) (figs. 34 and 36).

The prepumping vertical water-level differences 

between the Vincentown aquifer (A6) and the overlying 

lower Kirkwood-Cohansey aquifer (A8) are generally 

less than 20 feet, but as much as 60 feet in Camden 

County (figs. 35 and 37). Rates of ground-water recharge 

from the overlying aquifer are also greatest in Camden 

County, 0.2 to 3.0 in/yr. Ground water in the Vincentown 

aquifer is discharged to low-altitude areas along the 

outcrop or downward to the Wenonah-Mount Laurel 

aquifer. Hydraulic gradients within the Vincentown 

aquifer are similar to those in the underlying parts of the 

Wenonah-Mount Laurel aquifer.
SIMULATION OF GROUND-WATER FLOW H103

I

f

f
40° 75°

^

SAH.'TflN-'?_" j_j U"^%L

E L A W A R E V^

^39'

,75°

EXPLANATION

p H AREA OF DOWNWARD FLOW THROUGH THE TOP OF THE AQUIFER 

AREA OF UPWARD FLOW THROUGH THE TOP OF THE AQUIFER

0 10 15 MILES

0 5 10 15 KILOMETERS I/

74° 39°

y

I 1 SIMULATED OUTCROP DISCHARGE AREA Simulated prepumping flow to 

j____I streams from the unconfined outcrop areas is greater than the applied recharge 

rate of 20 inches per year

f ^~\ SIMULATED OUTCROP RECHARGE AREA Simulated prepumping flow to|_r a \ streams from the unconfined outcrop areas is less than the applied recharge

~" rate of 20 inches per year-7 LINE OF EQUAL SIMULATED PREPUMPING FLOW THROUGH THE TOP OF 

THE MIDDLE POTOMAC-RARITAN-MAGOTHY AQUIFER Interval, in inches 

per year, is variable

Oi iO

,0

COi iCO

i

a

O O O

FIGURE 76. Simulated prepumping flow through the top of the middle Potomac-Raritan-Magothy aquifer (model unit A2).
SIMULATION OF GROUND-WATER FLOW H105

1

I

I

I

I

T3

^3I

55 

I
ffi

40'

PENNSYLVANIA 

SIMULATED BOUNDARY OF AQUIFER"

.^'BURLINGTONK.S

EXPLANATION 

AREA OF DOWNWARD FLOW THROUGH THE TOP OF THE AQUIFERAREA OF UPWARD FLOW THROUGH THE TOP OF THE AQUIFER

SIMULATED OUTCROP DISCHARGE AREA Simulated prepumping flow to 

streams from the unconfined outcrop areas is greater than the applied recharge 

rate of 20 inches per year

SIMULATED OUTCROP RECHARGE AREA Simulated prepumping flow to 

streams from the unconfined outcrop areas is less than the applied recharge rate of 20 inches per year 0 5 10 15 KILOMETERS

0 LINE OF EQUAL SIMULATED PREPUMPING FLOW THROUGH THE TOP OF 

THE ENGLISHTOWN AQUIFER Interval, in inches per year, is variable

2 o

t-1> 

«o

SO OT03 i i 03

SO

H i i

OO O

FIGURE 78. Simulated prepumping flow through the top of the Englishtown aquifer (model unit A4).
SIMULATION OF GROUND-WATER FLOW H107

bo 

.S

1

1

O2
H108 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

The simulated prepumping flow in the Piney Point 

aquifer (A7) is dissimilar to flow in the underlying 

aquifers. Ground water within the Piney Point aquifer 

flows from the ground-water high in Burlington and 

Ocean Counties both downdip and to the southwest. The 

Piney Point aquifer is confined everywhere and the flow 

system is characterized as a more regional flow pattern 

that does not have local upward discharge areas beneath 

large rivers. This regional flow pattern is similar to flow 

patterns in downdip areas of the underlying aquifers.

Vertical water-level differences between the Piney 

Point aquifer (A7) and the overlying lower KirkwoodCohansey aquifer and confined Kirkwood aquifer (A8) 

are 0 to 20 feet in the eastern part of the aquifer but as 

much as 60 feet in the western part (figs. 36 and 37). 

Recharge from the overlying aquifer is greatest, 0 to 1.5 

in/yr, near the ground-water high. To the southwest, 

recharge is less than 0.2 in/yr. Areas of upward discharge, generally less than 0.2 in/yr, are in areas along 

the coast and in Burlington and Atlantic Counties 

beneath the Mullica River basin.

Simulated prepumping flow in the confined Kirkwood 

aquifer (A8) under prepumping conditions is from the 

updip limit of the aquifer to downdip areas. Vertical 

water-level differences between the confined Kirkwood 

aquifer (AS) and the overlying upper KirkwoodCohansey aquifer (A9) are from 10 to 30 feet (figs. 37 and 

38). Recharge and discharge through the top of the 

confined Kirkwood aquifer are generally less than 0.2 

in/yr (fig. 80). Upward leakage through the top of the 

confined Kirkwood aquifer is beneath the coast and the 

Mullica and Great Egg Harbor Rivers.

Recharge to the confined part of the upper KirkwoodCohansey aquifer (A9) in southern Cape May County is 

less than 0.2 in/yr from the overlying Holly Beach aquifer 

(AlO). Prepumping vertical water-level differences 

between these two aquifers are less than 10 feet (figs. 38 

and 39).

1978 TRANSIENT-STATE FLOW SYSTEM

Compared to the analysis of the prepumping flow 

system, the analysis of the 1978 flow system is more 

detailed because more measured data (Walker, 1983) are 

available. The simulated 1978 potentiometric surfaces 

(figs. 42-51) provide some additional information on the 

flow system in areas with few or no measured water 

levels, particularly in offshore areas. Simulated offshore 

water levels in the aquifers may not be the same as actual 

offshore water levels, because the model cannot be 

accurately calibrated without measured water levels in 

these areas. However, the simulated water levels provide estimates of hydraulic gradients within and between

I aquifers in offshore areas. Lateral hydraulic gradients 

within and vertical hydraulic gradients between aquifers 

are discussed. Simulated flow rates through the tops of 

selected aquifers are given, and regional recharge and 

discharge areas and hydraulic gradients are discussed. 

The reader is referred to Walker (1983) for a detailed 

discussion of 1978 water levels and water-level fluctuations in the major aquifers.

The steepest simulated lateral hydraulic gradients 

within the aquifers are near the major cones of depression. Large cones of depression have steeper simulated 

gradients on the updip side than on the downdip side. In 

the three Potomac-Raritan-Magothy aquifers (Al, A2, 

and A3), simulated lateral hydraulic gradients between 

the Delaware River and the center of the large cone of 

depression in central Camden County are about 10 ft/mi 

(figs. 42^44). Downdip of this large cone, hydraulic 

gradients within these aquifers are generally less than 5 

ft/mi. The steepest gradients in these aquifers are in the 

middle Potomac-Raritan-Magothy aquifer (A2) between 

the outcrop area and the steep cone of depression in 

Middlesex and northwestern Monmouth Counties (fig. 

43). Hydraulic gradients in this area are 15 to 20 ft/mi. 

Northeast of this cone of depression beneath Raritan 

Bay, gradients within the middle Potomac-RaritanMagothy aquifer are about 10 ft/mi. Hydraulic gradients 

in the Englishtown aquifer (A4) and the Wenonah-Mount 

Laurel aquifer (A5) are 25 to 30 ft/mi near the large cone 

of depression in southeastern Monmouth and northwestern Ocean Counties (figs. 45 and 46). Offshore of this 

cone, simulated hydraulic gradients are about 10 ft/mi 

within each of these aquifers. In the confined Kirkwood 

aquifer (A8), hydraulic gradients updip of the cone of 

depression at Atlantic City are 6 to 8 ft/mi, but simulated 

gradients in offshore areas are 2 to 4 ft/mi (fig. 49).

Simulated vertical gradients between aquifers and 

flow patterns within aquifers for 1978 differ from those in 

the prepumping flow system in both updip outcrop areas 

and downdip areas distant from the major cones of 

depression. Simulated vertical flow for 1978 in two cross 

sections of the Coastal Plain aquifers is shown in figure 

81. Simulated vertical flow rates in the 1978 flow system 

are between 0.0 and 0.2 in/yr in most areas, but rates of 

1 to 5 in/yr are common locally, particularly in updip 

areas and near the major cones of depression. Lateral 

flow within the aquifers is dominated by large regional 

cones of depression.

As in the simulated prepumping flow system, the 

vertical water-level differences between the lower and 

middle Potomac-Raritan-Magothy aquifers (Al and A2) 

are generally less than 10 feet (figs. 42 and 43). However, 

flow through the top of the lower Potomac-RaritanMagothy aquifer for January 1, 1978, (fig. 82) is greatly 

changed from prepumping conditions (fig. 75). Large
40° 75°

6 SIMULATED UPDIP LIMIT OR, 

OVERLYING CONFINING UNIT (.CSJ

A

EXPLANATION 

AREA OF DOWNWARD FLOW THROUGH THE TOP OF THE AQUIFERAREA OF UPWARD FLOW THROUGH THE TOP OF THE AQUIFER

SIMULATED OUTCROP DISCHARGE AREA Simulated prepumping flow to 

streams from the unconfined outcrop areas is greater than the applied recharge 

rate of 20 inches per year

SIMULATED OUTCROP RECHARGE AREA Simulated prepumping flow to 

streams from the unconfined outcrop areas is less than the applied recharge 

rate of 20 inches per year

0 LINE OF EQUAL SIMULATED PREPUMPING FLOW THROUGH THE TOP OF 

THE LOWER KIRKWOOD-COHANSEY AQUIFER AND CONFINED KIRKWOOD 

AQUIFER Interval 5 inches per year

§o 

a * 

aI

i

FIGURE 80. Simulated prepumping flow through the top of the lower Kirkwood-Cohansey aquifer and confined Kirkwood aquifer (model unit A8).
H110 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

0 10 20 30 KILOMETERS

______________I

NORTHWEST 

Fall Line

EXPLANATION

GENERALIZED DIRECTION

OF GROUND-WATER FLOW 

FLOW DIRECTION REVERSED 

FROM PREPUMPING CONDITIONS

| | AQUIFER 

[~~~] CONFINING UNIT __

HYDROGEOLOGICUNIT

A10 Holly Beach aquifer

C9 Estuarine clay confining unit

A9 Upper Kirkwood-Cohansey aquifer

C8 Confining unit overlying the Rio Grande water-bearing zone

A8 Lower Kirkwood-Cohansey aquifer and confined Kirkwood aquifer

C7 Basal Kirkwood confining unit

A7 Piney Point aquifer

C6 Vincentown-Manasquan confining unit

A6 Vincentown aquifer

C5 Navesink-Hornerstown confining unit

A5 Wenonah-Mount Laurel aquifer

C4 Marshalltown-Wenonah confining unit

A4 Englishtown aquifer

C3 Merchantville-Woodbury confining unit

A3 Upper Potomac-Raritan-Magothy aquifer

C2 Confining unit between the middle and upper Potomac-Raritan-Magothy aquifers

A2 Middle Potomac-Raritan-Magothy aquifer

C1 Confining unit between the lower and middle Potomac-Raritan-Magothy aquifers

A1 Lower Potomac-Raritan-Magothy aquifer

NORTHWEST 

Fall Line

Idealized interface where ground water 

contains 10,000 milligrams per liter 

chloride concentrations

FIGURE 81. Simulated flow in two hydrogeologic sections of the Coastal Plain, 1978.
' I N

SIMULATED BOUNDARY OF AQUIFER

 I / I TT-l

L A W A R E

CAPE MAY )^

EXPLANATION 

DOWNWARD FLOW THROUGH THE TOP OF THE AQUIFER

AREA OF UPWARD FLOW THROUGH THE TOP OF THE AQUIFER

SIMULATED OUTCROP RECHARGE AREA Simulated January 1 , 1978, flow 

to streams from the unconfined outcrop areas is greater than the applied recharge 

rate of 20 inches per year

0 LINE OF EQUAL SIMULATED JANUARY 1, 1978, FLOW THROUGH THE TOP

OF THE LOWER POTOMAC-RARITAN-MAGOTHY AQUIFER Interval, in inches 

per year, is variable

O2o^o 

» 

o d 2 

o

FIGURE 82. Simulated January 1, 1978, flow through the top of the lower Potomac-Raritan-Magothy aquifer (model unit Al).
H112 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

areas of upward discharge are shown for the lower 

Potomac-Raritan-Magothy aquifer in 1978. Although 

flow rates between the aquifers are generally less than 

1.0 in/yr, simulated upward discharge near the cone of 

depression at Camden is as high as 2.0 in/yr and downward recharge into the aquifer is generally between 1.0 

and 20.0 in/yr in northwestern Camden County. 

Although vertical water-level differences are relatively 

low, flow rates between the lower and middle PotomacRaritan-Magothy aquifers are high because of the high 

leakance of the intervening confining unit. Downward 

leakage greater than 20 in/yr for two nodes in northwestern Camden County is unrealistically high and reflects 

similar high flow through overlying confining units. This 

high flow results from the availability of an unlimited 

source of water from the overlying constant-head stream 

boundary and probably indicates that the actual induced 

recharge into the aquifer is at a smaller rate over a larger 

area than is simulated by the model.

Simulated vertical water-level differences between the 

middle and upper Potomac-Raritan-Magothy aquifers 

(A2 and A3) in 1978 (figs. 43 and 44) are greater than the 

water-level differences in the prepumping flow system 

but are relatively small, generally less than 20 feet. The 

greatest simulated vertical water-level differences are in 

Salem County, where they are as much as 30 feet, and in 

Monmouth and Middlesex Counties, where they are as 

much as 70 feet. Simulated flow through the top of the 

middle Potomac-Raritan-Magothy aquifer for January 1, 

1978, is shown in figure 83. The major changes in flow 

from prepumping to 1978 conditions (fig. 76) are (1) high 

upward discharge, more than 1.0 in/yr from the middle 

Potomac-Raritan-Magothy aquifer near the area of the 

cone of depression in Camden County; (2) disappearance 

of upward discharge from the middle Potomac-RaritanMagothy aquifer under Raritan Bay, in Middlesex and 

northern Monmouth Counties, under the Delaware 

River, and under Delaware Bay adjacent to western 

Salem County; (3) increase in recharge along the outcrop 

area of the middle Potomac-Raritan-Magothy aquifer in 

Mercer and Middlesex County from about 3 to 5 in/yr; 

and (4) relatively high recharge, generally between 1.0 

and 20.0 in/yr, to the middle aquifer in northwestern 

Camden County. The downdip recharge greater than 20 

in/yr to the middle Potomac-Raritan-Magothy aquifer for 

five nodes near the Delaware River in Camden and 

Burlington Counties is unrealistically high for the same 

reasons indicated above for similar high flow into the 

lower Potomac-Raritan-Magothy aquifer (Al). Another 

important feature of the 1978 flow system is the relatively low recharge, less than 0.5 in/yr, over the steep 

cone in the middle aquifer near Raritan Bay.

The simulated vertical water-level differences 

between the upper Potomac-Raritan-Magothy aquifer

(A3) and the Englishtown aquifer (A4) in 1978 (figs. 44 

and 45) are much greater than those in the prepumping 

flow system. Head differences in 1978 are as much as 140 

feet in Camden County, 100 feet in western Monmouth 

County, and more than 180 feet in southern Monmouth 

and northeastern Ocean Counties. Simulated flow 

through the top of the upper Potomac-Raritan-Magothy 

aquifer for January 1, 1978, is shown in figure 84. 

Although most of the upper Potomac-Raritan-Magothy 

aquifer receives 0.0 to 0.5 in/yr of downward recharge, 

similar to prepumping conditions (fig. 77), some areas 

had significant changes in flow. These changes include (1) 

disappearance of discharge to the Delaware River and 

Bay near western Salem County; (2) changing of areas 

from high discharge to areas of high discharge between 

1.0 and 10.0 in/yr near the outcrop area in northern 

Camden, Gloucester, and Burlington Counties; (3) 

increase in recharge from over 1.0 to over 3.0 in/yr 

locally near the outcrop area in Middlesex County; (4) 

change in flow of about 3 in/yr beneath Raritan Bay, from 

over 1.0 in/yr of upward discharge to more than 2.0 in/yr 

of recharge; and (5) very low upward discharge (less than 

0.2 in/yr) in Ocean and Monmouth Counties (beneath the 

large cone of depression in the Englishtown aquifer). 

Flow rates are low beneath the cone in the Englishtown 

aquifer despite the extreme hydraulic gradients, because 

of the relatively low hydraulic conductivity of the intervening Merchantville-Woodbury confining unit (C3).

The 1978 transient-flow system within the three 

Potomac-Raritan-Magothy aquifers includes relatively 

high rates of recharge in and near the outcrop areas in 

Mercer and Middlesex Counties, along the Delaware 

River, and beneath Raritan Bay. Recharge from the 

Delaware River flows toward the large cone of depression in central Camden County and smaller cones in 

Salem County (figs. 42^14). Recharge from Mercer and 

Middlesex Counties flows toward the cones of depression 

near Raritan Bay or downdip. This downdip flow is 

discharged upward offshore or flows south westward, 

then updip to the Camden cone.

Simulated vertical water-level differences in 1978 

between the Englishtown aquifer (A4) and the WenonahMount Laurel aquifer (A5) are much smaller than those 

between the underlying upper Potomac-RaritanMagothy aquifer (A3) and the Englishtown aquifer. 

Vertical water-level differences are as much as 50 feet 

near the center of the large cone of depression near the 

coast in Monmouth and Ocean Counties, 0 to 10 feet in 

downdip areas away from the cone, and about 20 feet in 

updip areas (figs. 45 and 46). Simulated flow through the 

top of the Englishtown aquifer is shown in figure 85. 

Simulated flow rates between the Englishtown and 

Wenonah-Mount Laurel aquifers are much higher than 

those between upper Potomac-Raritan-Magothy and
SIMULATION OF GROUND-WATER FLOW H113

I

o

OH

f
H114 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN
SIMULATION OF GROUND-WATER FLOW H115

i

l

3
H116 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

Englishtown aquifers because of the relatively high 

leakance of the Marshalltown-Wenonah confining unit 

(C4) (table 8). Downward recharge from the WenonahMount Laurel aquifer over the large area of the cone of 

depression in the Englishtown aquifer is more than 0.5 

in/yr in 1978. Recharge into the Englishtown aquifer in 

the updip areas has increased since prepumping conditions (fig. 78) by as much as 1.5 in/yr in Camden County 

and about 1 in/yr in Monmouth County. The prepumping 

areas of upward discharge from the Englishtown aquifer 

are either eliminated or greatly reduced in the 1978 flow 

system, including areas within the outcrop.

Simulated vertical water-level differences between the 

Wenonah-Mount Laurel aquifer (A5) and the overlying 

aquifers in 1978 range from about 20 feet in updip and 

downdip areas in the southwest Coastal Plain to more 

than 180 feet in the area of the cone of depression in 

Monmouth and Ocean Counties (figs. 46-48). Flow 

through the top of the Wenonah-Mount Laurel aquifer is 

shown in figure 86. Downward recharge near the outcrop 

in 1978 is as much as 1.0 to 3.0 in/yr. Upward discharge 

near the outcrop in 1978 is less than that under prepumping conditions (fig. 79). Offshore from Monmouth and 

Ocean Counties, where there was upward discharge 

under prepumping conditions, are areas of downward 

recharge in 1978. Flow beneath Delaware Bay changed 

directions from prepumping conditions in areas southwest of Salem and Cumberland Counties.

The flow systems in the Englishtown (A4) and 

Wenonah-Mount Laurel (A5) aquifers are recharged 

from ground-water highs near the outcrops in Camden, 

Gloucester, and Monmouth Counties (figs. 45 and 46). 

Some flow from these areas is to local wells, to the 

ground-water low in Burlington County, or it is discharged upward offshore and into Delaware Bay. However, most of the recharge flows downdip and eastward 

to the area of the large cones of depression in Monmouth 

and Ocean Counties. A unique aspect of the flow system 

occurs beneath Delaware Bay offshore of Cumberland 

and Cape May Counties in the Wenonah-Mount Laurel 

aquifer, where water is discharged both downward to the 

upper Potomac-Raritan-Magothy aquifer (A3) and 

upward to overlying Piney Point aquifer (,A7). This flow 

from the Wenonah-Mount Laurel aquifer is caused by 

withdrawals in the adjacent aquifers in Delaware and 

New Jersey.

The simulated 1978 flow systems in the Vincentown 

(A6) and Piney Point (A7) aquifers (figs. 47 and 48) are 

very similar to the prepumping flow systems. Recharge 

into the Vincentown aquifer from the lower KirkwoodCohansey aquifer (A8) is 0.5 to 5.0 in/yr higher than 

under prepumping conditions because of increased downward discharge to the Wenonah-Mount Laurel aquifer 

(A5). Simulated 1978 water levels in the Vincentown

aquifer are about 20 feet higher than in most areas of the 

Wenonah-Mount Laurel aquifer (figs. 46 and 47). In 

eastern Monmouth County, they are up to 100 feet 

higher than water levels in the Wenonah-Mount Laurel 

aquifer. Recharge and discharge rates between the 

Piney Point and lower Kirkwood-Cohansey aquifers are 

changed only slightly from prepumping conditions. Prepumping recharge and discharge areas along the coast of 

Ocean County have changed to an area of downward 

recharge over the small cone of depression in the Piney 

Point (fig. 48) and to an area of increased upward 

discharge, 0.4 in/yr, under the limb of the cone of 

depression in the confined Kirkwood aquifer (A8) 

(fig. 49).

The simulated 1978 flow system in the unconfined 

lower and upper Kirkwood-Cohansey aquifers (A8 and 

A9) is generally unchanged from prepumping conditions. 

Simulated changes in water levels within the unconfined 

aquifers and changes in downward flow rates from the 

unconfined aquifers are insignificant. However, the flow 

in the confined Kirkwood aquifer (A8) and in the confined 

part of the upper Kirkwood-Cohansey aquifer (A9) has 

changed from prepumping conditions. Essentially all 

simulated flow in these confined aquifers is to the areas 

of the two cones of depression (figs. 49 and 50). One cone 

is centered near Atlantic City in the confined Kirkwood 

aquifer (A8) (fig. 49), and the other cone is in the confined 

part of the upper Kirkwood-Cohansey aquifer (A9) in 

Cape May County (fig. 50). Water-level differences 

between the confined Kirkwood aquifer and the upper 

Kirkwood-Cohansey aquifer are more than 70 feet near 

Atlantic City. Vertical water-level differences between 

the confined part of the upper Kirkwood-Cohansey aquifer and the Holly Beach aquifer (AlO) are more than 20 

feet. Simulated upward discharge under prepumping 

conditions in onshore areas and offshore in the Atlantic 

Ocean is not present in 1978 (fig. 87). However, flow 

rates into the confined parts of the lower and upper 

Kirkwood-Cohansey aquifers through overlying confining units are generally less than 0.2 in/yr in 1978.

SENSITIVITY ANALYSIS

Sensitivity simulations provide information on which 

the impact of assumptions and model input data on the 

simulation results can be evaluated. The sensitivity 

simulations are made with the model data used for 

calibration but with changes within a reasonable range to 

one of the hydraulic characteristics, such as aquifer 

storage, or to one of the model assumptions, such as 

location of the interface boundary. Data are changed for 

several model units, a single model unit, or for a limited 

area depending on the characteristic being tested. Water
40° 75°

PENNSYLVANIA

CAMDENj ''BURLINGTON

SIMULATED BOUNDARY OF AQUIFER EXPLANATION

SIMULATED OUTCROP RECHARGE AREA Simulated January 1, 1978, flowto 

streams from water-table aquifer through streambed confining unit is less than the applied recharge rate of 20 inches per year

,75°

5 10 15 MILES

0 5 10 15 KILOMETERS

AREA OF DOWNWARD FLOW THROUGH THE TOP OF THE AQUIFER Y

\ L ,

AREA OF UPWARD FLOW THROUGH THE TOP OF THE AQUIFER 0 LINE OF EQUAL SIMULATED JANUARY 1, 1978, FLOW THROUGH THE TOP

OF THE WENONAH-MOUNT LAUREL AQUIFER Interval, in inches per year,

is variable SIMULATED OUTCROP DISCHARGE AREA Simulated January 1, 1978, 

flow to streams from water-table aquifer through streambed confining unit 

is greater than the applied recharge rate of 20 inches per year

V 

___ ______________ COO2oo c! 2I 74° 39°

FIGURE 86. Simulated January 1, 1978, flow through the top of the Wenonah-Mount Laurel aquifer (model unit A5).
H118 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

f

f
SIMULATION OF GROUND-WATER FLOW H119

levels from the sensitivity simulation are compared to 

water levels from the calibration simulation. If a small 

change in a specified hydraulic characteristic produces 

large changes in water levels, the model is useful in 

refining initial estimates of that characteristic. Conversely, if a large change in a specified hydraulic characteristic produces very little water-level difference, the 

flow model is not effective for estimating that characteristic. Consequently, sensitivity simulations are also useful for identifying types of data needed to improve the 

simulation of flow within the aquifer system.

Evaluating model assumptions by sensitivity analysis 

is limited in several ways. Sensitivity analyses can be 

made only on a limited number of characteristics and 

areas, and therefore only a small percentage of the 

factors affecting flow in an area can be tested. Also, the 

results of model calibration are not unique, and a different combination of aquifer and confining-unit characteristics could have resulted in model calibration. Sensitivity analyses on different calibrated model data 

may result in different conclusions. However, within 

these limitations, the following sensitivity analyses provide a means for evaluating the simulation results and 

assumptions.

TRANSMISSIVITY AND VERTICAL LEAKANCE OF THE 

CONFINING UNITS

Sensitivity analyses of transmissivity and vertical 

leakance of the confining units were made for the area 

along the Delaware River and areas near the center of 

the large cones of depression in the three PotomacRaritan-Magothy aquifers (Al, A2, and A3) and the 

confined Kirkwood aquifer (A8). The areas near the 

center of the large cones were chosen because they are 

areas with high withdrawal rates and have a large 

amount of information on water levels; therefore, these 

areas of the model were better calibrated than other 

areas. The area along the Delaware River was chosen 

because it is an outcrop area near an area with high 

withdrawal rates.

Four simulations were made with transmissivity and 

leakance changes as listed in table 9 for the area of the 

cone of depression centered in Camden County. The 

model area and results of these sensitivity simulations 

are also summarized in table 9 (simulations 1 to 4). These 

simulations show that large changes in transmissivity 

and large increases in the leakance of the overlying and 

intervening confining units near the center of the cone of 

depression in Camden County have a significant effect on 

simulated water levels. These large effects on water 

levels indicate that additional data on these hydraulic 

characteristics in the areas of the cones of depression will

increase the accuracy of the model results. Decreases in 

vertical leakance of the Merchantville-Woodbury confining unit (C3) produced very little water-level change; 

therefore, lower estimates of leakance based on additional data in this area would not improve the accuracy of 

the model results.

Four sensitivity simulations were made by varying the 

transmissivity and vertical leakance of the sediments 

along the Delaware River. The data changes, model 

area, and results of these sensitivity simulations are 

given in table 9 (simulations 5 to 8). These simulations 

show that the rate of flow induced from the Delaware 

River is controlled more by vertical leakance of the 

confining units than by the transmissivity of the aquifers 

along the river. Although the simulated outcrop areas 

provide regional recharge to the ground-water flow 

system, the large cell size prevents accurate simulation 

of water levels in aquifer outcrop areas. Results and 

conclusions relating specifically to aquifer outcrop areas 

must be used cautiously and are useful as guidelines for 

more detailed studies in these areas.

Four sensitivity analyses were also made for the area 

near the center of the large cone of depression in Atlantic 

County, varying transmissivity and leakance. The data 

changes, model area, and results of these sensitivity 

simulations are given in table 9 (simulations 9 to 12). 

These simulations show that, like the water levels in the 

Potomac-Raritan-Magothy aquifers (Al, A2, and A3), 

simulated water levels in the confined Kirkwood aquifer 

(A8) are greatly affected by large changes in transmissivity or in leakance of the overlying confining unit. 

Therefore, the accuracy of the model results would be 

improved by additional data on these hydraulic characteristics in this area. Some change in transmissivity or 

leakance could be made in the calibrated model to 

produce more acceptable simulated water levels, but 

these changes would have to be much smaller than the 

range of values tested in these sensitivity analyses.

Two additional sensitivity simulations were made of 

the transmissivity of the confined Kirkwood aquifer (A8) 

(simulations 13 and 14, table 9). The water-level changes 

in these sensitivity simulations are not large; however, 

the simulations show that horizontal flow through only a 

one- or two-cell width along the updip limit of the 

confined Kirkwood aquifer significantly affects water 

levels near Atlantic City. The hydraulic connection 

between the unconfined lower Kirkwood-Cohansey aquifer and the confined Kirkwood aquifer is not well defined 

(Zapecza, 1984, p. 29). Therefore, additional data on the 

hydraulic characteristics between the unconfined lower 

Kirkwood-Cohansey aquifer and the confined Kirkwood 

aquifer will improve model results near the center of the 

cone.
H120 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

TABLE 9. Results of sensitivity analyses on transmissivity and confining-unit leakance

Model unit: Al, lower Potomac-Raritan-Magothy aquifer A7, Piney Point aquifer

A2, middle Potomac-Raritan-Magothy aquifer A8, lower Kirkwood-Cohansey and confined Kirkwood aquifers

A3, upper Potomac-Raritan-Magothy aquifer A9, upper Kirkwood-Cohansey aquifer

A4, Englishtown aquifer A10, Holly Branch

A5, Wenonah-Mount Laurel aquifer Nodes: Location shown on figure 25

A6, Vincentown aquifer

Simulation Model 

unit

Nodes

Rows Columns

General description of change 

made to calibrated data Resulting water-level changes for January 1, 1978

10

11

12

13

14

Al, A2, 5-10 18-25 100 percent increase in transmissivity 

and A3 in the confined Potomac-RaritanMagothy aquifers and in Camden, 

Gloucester, and Burlington Counties. 

Same as above, but a 50-percent 

decrease.

C3 5-10 18-25 An order-of-magnitude increase in 

leakance of the MerchantyilleWoodbury confining unit in Camden, 

Gloucester, and Burlington Counties.

Same as above, but an order-ofmagnitude decrease.

Al, A2, 2-4 18-25 100-percent increase in transmissivity 

and A3 in the Potomac-Raritan-Magothy

aquifers near the Delaware River in 

Camden and Burlington Counties. 

Same as above except a 50-percent 

decrease.

Cl, C2, 2-4 18-25 An order-of-magnitude increase in 

and C3 leakance in the confining units above 

the Potomac-Raritan-Magothy aquifers along their outcrops in Camden, 

Gloucester, and Burlington Counties. 

Same as above, but an order-ofmagnitude decrease.

A8 16-271 2-501 100-percent increase in transmissivity in the confined Kirkwood aquifer 

in Atlantic, Cape May, and Ocean 

Counties.

Same as above, but a 50-percent 

decrease.

C8 16-271 2-501 An order-of-magnitude increase in 

leakance in the confining unit overlying the Rio-Grande water-bearing 

zone in Atlantic, Cape May, and 

Ocean Counties.

Same as above, but an order-ofmagnitude decrease.

A8 16-192 11-362 100-percent increase in transmissivity 

in A8 along the updip limit of the 

confined Kirkwood aquifer. 

Same as above, but a 67-percent 

decrease.

Cone of depression is about 15 ft shallower in Al 

and A2 and 30 ft shallower in A3.

Cone of depression is about 20 ft deeper in Al and 

A2 and 30 ft deeper in A3. Less than 5-ft waterlevel decline in downdip areas of Al and A2.

Cone of depression is about 15 ft shallower in Al 

and A2 and 30 ft shallower in A3. Ground-water 

high above cone in A4 is about 20 ft lower, 40 ft 

lower locally. Similar ground-water highs in A5 and 

A6 are about 10 ft lower.

Cone of depression is about 5 ft deeper in Al and 

A2 and 10 ft deeper in A3. Ground-water high in 

A4 is about 15 ft higher. Less than 5-ft water-level 

decline in downdip areas of Al, A2, and A3.

Cone of depression is about 10 ft shallower in Al, 

A2, and A3. Water levels near the Delaware River 

are about 10 ft higher in Al.

Cone of depression is about 10 ft deeper and heads 

near the Delaware River are up to 20 ft lower in 

Al, A2, and A3. Water levels in Salem County are 

about 10 ft lower.

Cone of depression is about 30 ft shallower in Al, 

A2, and A3. Water levels are 5 ft higher in downdip areas of Al, A2, and A3.

Cone of depression is about 80 ft deeper in Al, 70 

ft deeper in A2, and 40 ft deeper in A3. Water levels near the Delaware River are up to 100 ft lower 

in Al and 70 ft lower in A2 and A3. Water levels 

declined 15-20 ft in downdip areas, 10 ft in western 

Salem County, and about 5 ft or less near Raritan 

Bay. Local 20-ft water-level declines in A4.

Cone of depression is about 30 ft shallower near 

the center in A8. Water levels near the offshore 

boundary are 5 ft higher in A8 and 10 ft higher in 

A7.

Cone of depression is about 50 ft deeper near the 

center in A8. Water levels near the offshore boundary are about 10 ft lower in A7.

Cone of depression is about 35 ft shallower near the 

center in A8. Water levels near the offshore boundary are 10 ft higher in A7 and A8.

Cone of depression is about 20 ft deeper near the 

center in A8. Water levels near the offshore boundary are 20 ft lower in A8 and 10 ft lower in A7.

Cone of depression is about 10 ft shallower near the 

center in A8 and water levels near the offshore 

boundary in A7 and A8 are 5 ft higher.

Cone of depression is about 15 ft deeper near the 

center in A8 and water levels near the offshore 

boundary in A7 and A8 are 5 ft lower.

1 Only those areas where A8 is confined.

2 Only those areas near the updip limit of unit A8.
SIMULATION OF GROUND-WATER FLOW H121

AQUIFER STORAGE

Simulated water levels were tested for sensitivity to 

changes in the storage coefficient of the confined aquifers. Decreasing the storage coefficient two orders of 

magnitude everywhere in all confined aquifers changed 

the 1978 simulated water levels generally less than 5 

feet. Increasing the storage coefficient two orders of 

magnitude for all confined aquifers significantly changed 

simulated water levels in the large cones of depression in 

the Englishtown and Wenonah-Mount Laurel aquifers 

(A4 and A5) in Ocean and Monmouth Counties. Simulated water levels in 1978 were about 50 feet higher in 

this area for each order of magnitude increase in the 

storage coefficient. Simulated water levels increased 

about 10 feet for every order of magnitude increase in 

storage in other major cones of depression, including 

cones in the three Potomac-Raritan-Magothy aquifers 

(Al, A2, and A3) near Camden, in the confined Kirkwood 

aquifer (A8) near Atlantic City, and in the middle aquifer 

of Potomac-Raritan-Magothy aquifer system (A2) in 

Middlesex County.

Most of the aquifer-test results shown in table 3 are 

within an order of magnitude of the storage coefficient 

used in the calibrated model. The sensitivity simulations 

indicate that the storage coefficients used in the calibrated model are reasonable, because simulated water 

levels are not sensitive to decreases in the storage 

coefficient and increases of one and two orders of magnitude give storage coefficients that are close to storage 

coefficients of unconfined aquifers.

DOWNDIP BOUNDARIES

Simulated water levels were tested for sensitivity to 

the position of the southeast downdip boundaries of 

several aquifers. In the Potomac-Raritan-Magothy aquifers (Al, A2, And A3), the downdip boundary is the 

idealized interface between the freshwater and saltwater 

flow systems at the estimated occurrence of 10,000 mg/L 

chloride concentrations. Several simulations were made 

with the interface moved to various distances further 

offshore. The interface was not moved to a closer onshore 

position because there is no evidence to indicate that 

10,000 mg/L chloride concentrations exist further northwest than initially estimated. Simulated water levels 

were not sensitive to moving the interface boundary 

seaward. In the sensitivity simulation with the boundary 

moved as far offshore as possible in the model, the 

interface was about 50 miles seaward from the boundary 

used in the calibrated model for the middle and upper 

Potomac-Raritan-Magothy aquifer system (A2 and A3) 

and 75 to 100 miles seaward from the boundary in the 

calibrated model in the lower Potomac-Raritan-Magothy

aquifer (Al). In this simulation, simulated 1978 water 

levels changed less than 5 feet in all aquifers.

Simulated water levels were also tested for sensitivity 

to the estimated downdip extent of several aquifers that 

thin or become silty. The downdip extent of the Piney 

Point (A7) and the Wenonah-Mount Laurel (A5) aquifers 

was extended about 50 miles farther downdip, and 

simulated water levels changed less than 5 feet. Water 

levels in the Englishtown aquifer (A4) are most sensitive 

to the position of the aquifer's downdip extent. Extending the aquifer's downdip boundary 40 to 75 miles from 

that used in the calibrated model changed simulated 

water levels 30 to 50 feet near the center of the large 

cone of depression in Monmouth and Ocean Counties. 

Simulated water levels northwest of the cone changed 

less than 5 feet, offshore water levels and water levels to 

the south changed about 10 feet. Extending the aquifer's 

downdip extent 10 to 50 miles changed simulated water 

levels 10 to 20 feet near the center of the cone of 

depression. During calibration, water levels near the 

center of the cone of depression were also sensitive to the 

estimated limit of the upper sand unit of the Englishtown 

aquifer system. Although model unit A4 represents both 

the upper and lower sand units, the upper sand unit is 

not present downdip and offshore of Ocean and southern 

Monmouth Counties, and low transmissivity (less than 

500 ft2/d) in this area represents only the lower aquifer 

(fig. 58). In the calibrated model, the limit of the upper 

aquifer and the low transmissivities are estimated to be 

about 5 miles offshore. Moving the limit 3 to 8 miles 

farther offshore changed simulated water levels in the 

cone of depression several tens of feet.

These simulations suggest that the estimated position 

of the freshwater-saltwater interface boundary does not 

significantly affect simulated water levels and does not 

seriously limit model results. The estimated downdip 

extent of the Piney Point (A7) and Wenonah-Mount 

Laurel (A5) aquifers also does not significantly affect 

simulated water levels. However, water levels in the 

Englishtown aquifer (A4) are sensitive to the estimated 

downdip limit of the aquifer and the downdip limit of 

upper sand unit offshore of Ocean and Monmouth Counties. Therefore, the accuracy of model results near the 

cone of depression in Monmouth and Ocean Counties 

depends on the accuracy of the location of the downdip 

limit of the Englishtown aquifer.

BOUNDARY FLOWS

Simulated water levels were tested for sensitivity to 

the amount of flow used to simulate lateral boundary 

conditions for the aquifers along the southwest, southeast, and northeast boundaries. Total boundary flows 

used in the calibrated model for each pumping period are
H122 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

TABLE 10. Boundary flows for prepumping conditions and for 

January 1, 1978, for each aquifer

Model unit: Al, lower Potomac-Raritan-Magothy aquifer

A2, middle Potomac-Raritan-Magothy aquifer

A3, upper Potomac-Raritan-Magothy aquifer

A4, Englishtown aquifer

A5, Wenonah-Mount Laurel aquifer

A6, Vincentown aquifer

A7, Piney Point aquifer

A8, lower Kirkwood-Cohansey and confined Kirkwood aquifer

A9, upper Kirkwood-Cohansey aquifer 

A10, Holly Beach

Boundary flows: Positive flows are into model area, negative flows are out of 

model area.

Boundary flows (million gallons per day)

Model 

unit

Prepumping January 1, 1978

South- South- North- South- South- Northwestern eastern eastern western eastern eastern 

boundary boundary boundary boundary boundary boundary

Al

A2

A3

A4

A5

A6

A7

A8

A9

A10

Total

0.850

.426

.106

.048

.118

.153

.035

.093

-.811

1.018

-0.065

.101

.036

-0.106

-1.431

-3.379

-.409

-.067

-.051

-.246

-.093

-5.782

0.351

1.477

-.040

.013

.035

.072

-1.202

.065

1.112

1.883

0.371

.244

.615

0.060

.947

1.613

.276

.039

.016

-.134

-.095

2.722

given in table 7. Boundary flows for each boundary in the 

prepumping simulation and in pumping period 8 

(1973-78) of the transient simulation are shown in table 

10. Three sensitivity simulations were made with (1) no 

boundary flows, (2) 2 times the boundary flows used in 

the calibrated model, and (3) 10 times the boundary flows 

used in the calibrated model. The results of the sensitivity simulations are shown in table 11.

Interpretation of these sensitivity simulations is limited by the relation of the boundary flows to the aquifer 

and confining-unit hydraulic characteristics near the 

boundaries. The amount of lateral flow at a boundary is 

calculated from the transmissivity and hydraulic gradients. The hydraulic gradients, however, are dependent 

on the confining-unit properties, which control vertical 

leakage, and the transmissivity. Changing only the flow 

at the boundaries, as was done in the sensitivity simulations, makes the boundary flows incompatible with transmissivity and vertical leakance at the boundaries. That 

is, lateral boundary flows that differ from those used in 

the calibrated model are not probable without also 

having different aquifer and confining-unit characteristics near the boundaries. The simulations described in 

this section do not show the sensitivity of simulated 

water levels to conditions at the flow boundaries. However, the simulations show the general significance of 

boundary flows to water levels within the New Jersey

Coastal Plain aquifers, assuming the transmissivity and 

vertical-leakance values are those of the calibrated 

model.

The results of the three sensitivity simulations indicate 

that simulated water levels for most of the modeled 

aquifers are not significantly affected by large changes in 

boundary flows. Also, the amount of lateral flow at the 

boundaries has a minimal effect on estimates of transmissivity and leakance derived from model calibration. 

Large water-levels changes are generally near the 

boundaries and are not significant 5 to 10 miles away 

from the boundaries. Simulated water levels are most 

sensitive to boundary flows along the southwest model 

boundary between Delaware and New Jersey, in the 

three Potomac-Raritan-Magothy aquifers (Al, A2, A3), 

the Piney Point aquifer (A7), and the two KirkwoodCohansey aquifers (A8 and A9). However, simulated 

water levels are affected very little, generally less than 

10 feet, for changes in flow up to 100 percent along the 

northeast boundary.

As an estimate of actual flows at the boundaries, the 

flows used in the model may be in error by as much as 100 

percent locally. However, boundary flows are probably 

not in error by this much everywhere along the boundaries. Boundary flows are relatively small compared to 

withdrawals (less than 3 percent) and generally have 

only a small (less than 10 feet) effect on simulated water 

levels. Therefore, the lateral boundary flows used in the 

calibrated model are reasonable regional estimates of the 

flow.

CONFINING-UNIT STORAGE

Three sensitivity simulations were made to determine 

the effects of confining-unit storage on simulated water 

levels. No confining-unit storage had been used in the 

calibrated model. Specific storages of 6xlO~6/ft, 

6xlO~5/ft, and 6xlO~4/ft for the confining units cause 

extreme changes in 1978 simulated water levels. In the 

simulation with a confining-unit specific storage of 

6xlO~4/ft, water levels are 150 to 200 feet higher at the 

large cone of depression in Monmouth and Ocean Counties in the Englishtown and Wenonah-Mount Laurel 

aquifers (A4 and A5). Water levels for this simulation 

were 20 to 80 feet higher near the large cone of depression in Camden County in the three Potomac-RaritanMagothy aquifers (Al, A2, and A3). In the simulation 

with a confining-unit specific storage of 6xlO~5/ft, water 

levels in the Englishtown and Wenonah-Mount Laurel 

aquifers are 75 to 130 feet higher in Monmouth and Ocean 

Counties. Water levels in the Potomac-Raritan-Magothy 

aquifers are 10 to 40 feet higher in Camden County. 

Model calibration would not be possible using these 

values of confining-unit specific storage, as model transmissivity and confining-unit leakance would have to be
SIMULATION OF GROUND-WATER FLOW H123

TABLE 11. Results of boundary-flow sensitivity analysis

Simulation 1: No boundary flows in any unit.

Simulation 2: Two times the boundary flows used in calibration for each unit.

Simulation 3: Ten times the boundary flows used in calibration for each unit.

Model unit: Al, lower Potomac-Raritan-Magothy aquifer 

A2, middle Potomac-Raritan-Magothy aquifer 

A3, upper Potomac-Raritan-Magothy aquifer 

A4, Englishtown aquifer

A5, Wenonah-Mount Laurel aquifer 

A6, Vincentown aquifer 

A7, Piney Point aquifer

A8, lower Kirkwood-Cohansey and confined Kirkwood aquifer 

A9, upper Kirkwood-Cohansey aquifer 

A10, Holly Beach

Resulting water-level changes for January 1, 1978

Model 

unit

Al

A2

A3

Simulation Southwest 

number boundary

1

2

3

1

2

3

1

2

3

10-25 ft lower, 

200 ft lower locally.

5-10 ft higher

20-90 ft higher,

180 ft higher locally.

10-15 ft lower

5-15 ft higher

20-140 ft higher

0-5 ft lower

10 ft higher

35-75 ft higher

Southeast 

boundary

5 ft lower to 

15 ft higher.

0-5 ft higher

5 ft lower to

90 ft higher.

0-15 ft higher

0-15 ft higher

15 ft lower to

140 ft higher.

Northeast 

boundary

5 ft lower

5-15 ft higher

Other areas

Cone of depression in Camden County, 10 ft

shallower.

Cone of depression in Middlesex and Monmouth

Counties, 5 ft shallower.

Same area as above, 5 ft shallower.

Same area as above, 5-10 ft shallower. Cone of

depression in Camden County, 5 ft shallower.

- 0-5 ft higher -

5 ft lower to

10 ft higher.

15 ft lower to

35 ft higher.

0-15 ft higher

15-35 ft higher Cone of depression in Camden County, 5-10 ft

shallower. Cone of depression in Monmouth County,

5-10 ft shallower.

A4

A5

A6

A7

A8

A9

1

2

3

1

2

3

1

2

3

1

2

3

1

2

3

1

2

3

10 ft higher

5 ft higher

10-35 ft higher

10 ft higher

10-70 ft lower

10 ft lower

10 ft higher

40-110 higher

5-15 ft lower

5-15 ft higher

55-130 ft higher

- 0-10 ft higher

 5-10 ft higher

10-35 ft higher 10-45 ft higher

0-15 ft higher 10 ft higher

5-10 higher 

5-25 ft higher 25-40 ft higher

 

 

 

 

 

5-10 ft higher -

0-10 ft lower -

5-10 ft higher 5 ft higher

30-40 ft higher 5-40 ft higher

5 ft lower 

5 ft higher 5 ft higher

10-55 ft higher 0-40 ft higher

Cone of depression in Atlantic County, 10 ft

shallower.

Cone of depression in Cape May County, 5 ft deeper.

Same area as above, 5 ft shallower.

Same area as above, 30 ft shallower.

unreasonably low. These sensitivity simulations show 

that confining-unit specific storages of 6.0xlO~4/ft and 

6.Ox 10~5/ft are probably higher than the specific storage 

of the New Jersey Coastal Plain confining units.

In the simulation with a confining-unit storage of 

6x 10~6/ft, water-level changes are much less than in the 

other two simulations. The greatest increase in water 

levels occurs in the Englishtown and Wenonah-Mount 

Laurel aquifers (A4 and A5). In these aquifers, 1978 

water levels near the center of the cone of depression in 

Monmouth and Ocean Counties are 25 to 50 feet higher. 

Water levels in downdip areas of these aquifers are 10 to 

60 feet higher than those of the calibration simulation. In 

all other aquifers, water levels near the center of the

cones of depression are less than 10 feet higher, and 

water levels in downdip areas are 5 to 25 feet higher.

The results of this simulation suggest that calibration 

of the New Jersey RASA model would be possible with 

a confining-unit storage value of 6xlO~6/ft or less and 

somewhat lower values of aquifer storage, transmissivity, or confining-unit leakance. The calibration simulation with no confining-unit storage simulates only steady 

leakage through the confining units. Although actual 

transient leakage from the confining units is not directly 

simulated in the calibrated model, the release of water 

from confining units is probably indirectly simulated in 

the release of water from aquifer storage. To better 

simulate the release of water from storage from aquifers
H124 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

and confining units, aquifer storage should be based on 

actual aquifer thickness and an estimate of aquifer specific storage rather than a constant storage coefficient as 

was used for most of the aquifers in the calibrated model. 

Present data on confining-unit specific storage are 

very limited. An estimate of specific storage of 3x 1CT6 to 

6xlO~6/ft for the confining sediments overlying the 

Piney Point aquifer in Delaware was derived from an 

aquifer-test analysis by Leahy (1976, p. 22). Estimates of 

land subsidence near Atlantic City in Atlantic County are 

about 0.06 in/yr based on subsidence measurements at a 

monitoring station by the U.S. Geological Survey (P.P. 

Leahy, oral commun., 1985). This subsidence is attributed primarily to inelastic compaction of the confining 

units in the upper part of the Coastal Plain resulting from 

declining water levels. Elastic specific storage estimated 

from subsidence data is about 1.3xlO~6/ft for the basal 

Kirkwood confining unit (C7) (P.P. Leahy, oral commun., 1985), and the relatively small amount of subsidence suggests that inelastic confining-unit specific storage within the Coastal Plain is also relatively low. 

However, subsidence data have been collected for a 

relatively short period of time, since 1980, and are only 

from sediments in the upper part of the Coastal Plain. 

Not enough data are available to justify including 

confining-unit specific storage in the calibration simulation of the RASA model.

ADDITIONAL EVALUATION OF FLOW AND BOUNDARY 

CONDITIONS

TRANSIENT-FLOW CONDITIONS

The rate at which water levels change in response to 

changes in withdrawals and the time it takes for steadystate conditions to be reached after a change in withdrawals are important aspects of the transient-flow 

conditions within the New Jersey Coastal Plain aquifers. 

Two simulations were made to analyze these aspects by 

simulating the effects of (1) continued withdrawals from 

1981 to 2011 at the 1978-80 withdrawal rate and (2) no 

withdrawals after 1980. The second simulation is based 

on the additional assumption (to those discussed previously) that the aquifers are totally elastic. Both simulations had simulated January 1, 1981, water levels (pumping period 9) as initial conditions.

In the first simulation, with continued withdrawals, 

water levels declined very little, less than 5 feet, in the 

upper aquifers (the Vincentown to the upper KirkwoodCohansey aquifers, A6 to A9) and near the center of the 

major cones of depressions. However, water levels 

farther from the major cones declined as much as 25 feet. 

In the three Potomac-Raritan-Magothy aquifers (Al, 

A2, and A3), the center of the large cone of depression in 

central Camden County declined less than 2 feet after

1980 with continued withdrawals at the 1978-80 rate. 

Similarly, water levels in the cone of depression in 

Middlesex and Monmouth Counties in the middle 

Potomac-Raritan-Magothy aquifer also declined less 

than 2 feet. Water levels in downdip areas of the three 

Potomac-Raritan-Magothy aquifers near the northeast 

model boundary declined between 18 and 25 feet by the 

end of the simulation. Water levels in downdip areas near 

the southwest boundary declined less than 5 feet. In the 

Englishtown and Wenonah-Mount Laurel aquifers (A4 

and A5), water levels near the major cone of depression 

in Monmouth and Ocean Counties declined 4 feet by the 

end of the simulation, but water levels in downdip areas 

near the northeast model boundary declined 17 feet. 

Water levels in downdip areas near the southwest model 

boundary declined only 6 feet in these aquifers. Water 

levels in the two Kirkwood-Cohansey aquifers (A8 and 

A9) declined less than 2 feet everywhere.

In general, the simulation of continued withdrawal at 

the 1978-80 rate to 2011 showed that near the large cones 

of depression, the flow system is very close to steadystate conditions, and water levels in these areas would 

change less than 5 feet if pumpage rates did not change. 

However, in downdip areas farther from the major cones 

of depression, water levels are under transient conditions and water levels would decline as much 25 feet with 

no change in pumpage rates. Also, in areas near the 

major cones, if pumpage rates did not change, 50 percent 

of the water-level decline would occur in 6 years and 75 

percent would occur in 12 years. In areas away from the 

major cones, 50 percent of the water-level decline would 

occur in 8 years and 75 percent of the cones would occur 

in 16 years. This simulation also showed that after 10 

years, changes in water levels would be less than 1 ft/yr 

everywhere.

The second simulation simulated the effects of no 

withdrawals after 1980. Generally, water levels near the 

center of the major cones of depression react quickly to 

changes in withdrawals compared to areas farther from 

the cones. The Potomac-Raritan-Magothy aquifers (Al, 

A2, and A3) in central Camden County and the confined 

Kirkwood aquifer (A8) in Atlantic County had simulated 

drawdowns from prepumping conditions to 1981 of as 

much as 100 feet. With no withdrawals after 1980, 

simulated water levels recovered about 95 percent, or to 

within about 5 feet of prepumping water levels, in 2 

years. In the Englishtown and Wenonah-Mount Laurel 

aquifers (A4 and A5) near the center of the large cone of 

depression in Monmouth and Ocean Counties, drawdowns were as much as 285 feet from prepumping 

conditions to 1981. With no pumpage after 1980, simulated water levels recovered about 95 percent, or to 

within 14 feet of prepumping water levels, in 6 years. In 

downdip areas near the southeast model boundary in the
SIMULATION OF GROUND-WATER FLOW H125

lower Coastal Plain aquifers (the lower PotomacRaritan-Magothy to the Wenonah-Mount Laurel aquifers, Al to A5), drawdowns from prepumping conditions 

to 1981 were from 40 to 55 feet. With no pumpage after 

1980, water levels recovered 50 percent in 12 years and 

75 percent in 16 years. Water levels in the upper 

Potomac-Raritan-Magothy, Englishtown, and WenonahMount Laurel aquifers (A3, A4, and A5) continued to 

decline for 2 years after 1980. In downdip areas of these 

aquifers near the southwest boundary, drawdowns were 

about 25 feet from prepumping conditions to 1981. With 

no pumpage after 1980, water levels in the downdip areas 

of these aquifers recovered about 75 percent in 12 years. 

In general, the simulation with no pumpage after 1980 

showed that, assuming the aquifers are totally elastic, 

water levels near the major cones would recover quickly 

in the absence of pumpage 95 percent in 2 to 6 years. 

However, water levels farther from the cones would 

recover more slowly 75 percent in 12 to 16 years. Also, 

after about 26 years, water-level recovery would be less 

than 1 ft/yr everywhere.

FLOW NEAR THE DOWNDIP BOUNDARY

In the steady-state prepumping flow system, areas of 

upward discharge along the southeast boundary are 

simulated in the upper Potomac-Raritan-Magothy, 

Wenonah-Mount Laurel, Piney Point, confined Kirkwood, and upper Kirkwood-Cohansey aquifers (A3, A5, 

A7, A8, and A9), and in small areas of the lower and 

middle Potomac-Raritan-Magothy aquifers (Al and A2) 

and the Englishtown aquifer (A4) (figs. 75-^80). The 

lower and middle Potomac-Raritan-Magothy aquifers 

and the Englishtown aquifer have downward flow 

through overlying confining units along most of the 

southeastern interface boundary. In all of the above 

aquifers, flows along this boundary are less than 0.01 

in/yr and are smaller than the error in estimating these 

flows using the calibrated model.

The downward direction of simulated flow to the lower 

and middle Potomac-Raritan-Magothy aquifers (Al and 

A2) may indicate that the conceptual model of generally 

upward flow along the interface is too simplified. Prepumping leakage from the overlying upper PotomacRaritan-Magothy aquifer (A3) flows updip within the 

middle and lower Potomac-Raritan-Magothy aquifers 

and is discharged along the outcrop area near the Delaware River. The amount of leakage, transmissivity of the 

lower and middle Potomac-Raritan-Magothy aquifers, 

and the vertical leakance of the overlying confining units 

caused the direction of flow in downdip areas to be lateral 

along the interface boundary and updip rather than 

upward through overlying confining units.

After pumping began, the areas of upward flow along 

the southeastern model boundary were affected by withdrawals from the aquifers. Changes in the direction of 

vertical flow along the southeastern boundary between 

prepumping and 1978 flow conditions occur in the three 

Potomac-Raritan-Magothy aquifers, the WenonahMount Laurel aquifer, the confined Kirkwood aquifer, 

and the upper Kirkwood-Cohansey aquifer (Al, A2, A3, 

A5, A8, and A9). Flow along the southeastern boundary 

is downward in 1978 through the confining unit overlying 

the Rio Grande water-bearing zone and the estuarine 

clay confining unit (C8 and C9) overlying the KirkwoodCohansey aquifers, although it is upward through the 

basal Kirkwood confining unit (C7) overlying the Piney 

Point aquifer. Flow through the Navesink-Hornerstown 

confining unit (C5) overlying the Wenonah-Mount Laurel 

aquifer is downward along the southeastern boundary 

offshore of Ocean County (fig. 86). Flow through the 

three confining units overlying the Potomac-RaritanMagothy aquifers (Cl, C2, and C3) is downward along 

the southeastern boundary offshore of Ocean County 

(figs. 82-84).

The southeast boundaries of the three PotomacRaritan-Magothy aquifers (Al, A2, and A3) represent an 

idealized freshwater-saltwater interface (figs. 3, 5, and 

7). The southeast boundaries of the confined Kirkwood 

and upper Kirkwood-Cohansey aquifer (A8 and A9) are 

flow boundaries at the downdip limit of the model, which 

is several tens of miles updip from the assumed position 

of the freshwater-saltwater interface in these aquifers 

(figs. 17 and 19). Although the interface is assumed to be 

an immovable no-flow surface, it is actually a transition 

zone of chloride concentrations, the position of which is 

affected by flow in both the saltwater and freshwater 

flow systems. This transition zone is expected to move 

landward as withdrawals change the flow system. Simulated drawdowns along the interface boundary from 

prepumping conditions to 1978 are as follows: as much as 

60 feet in the lower Potomac-Raritan-Magothy aquifer, 

45 feet in the middle Potomac-Raritan-Magothy aquifer, 

and 35 feet in the upper Potomac-Raritan-Magothy aquifer. Simulated drawdowns from prepumping conditions 

to 1978 along the southeast flow boundary are 20 feet in 

the confined Kirkwood aquifer and 10 feet in the upper 

Kirkwood-Cohansey aquifer. Lateral hydraulic gradients 

in these downdip areas are greatest, 1 ft/mi, in the 

confined Kirkwood aquifer (A8).

Simulated hydraulic gradients within the aquifers near 

the interface boundary cannot be used to estimate movement of the interface, although simulated changes in 

hydraulic gradients indicate a potential for interface 

movement. Any change in water level at the boundary or 

change in gradients near the boundary creates the potential for interface movement. Even if the simulated flow
H126 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

direction within an aquifer near the interface is toward 

the interface, if water levels or lateral gradients near the 

interface have decreased from prepumping conditions, 

the interface is under the potential to move updip. By 

comparing transmissivity values, the amounts of drawdowns, and changes in hydraulic gradients in each aquifer, the lower Potomac-Raritan-Magothy aquifer (Al) 

and the confined Kirkwood aquifer (A8) have the greatest potential for landward movement of the interface.

SOURCE OF WATER TO WELLS

The source of water to wells is analyzed below by using 

ground-water budgets. The rates of horizontal and vertical flow are determined for four major cones of depression in seven aquifers and the relative amounts of water 

derived from aquifer storage, boundary flows, and flow 

from constant-head nodes are summarized for each 

pumping period and aquifer. The source of water to wells 

in the major cones is the difference between prepumping 

and January 1, 1978, flow rates into and out of the areas. 

The source of water to wells in these areas is summarized 

as decreases and increases in horizontal and vertical 

outflow and inflow. As in other analyses, the budget 

figures presented in this section are regional estimates 

and may be useful as initial estimates of the source of 

water to wells locally. However, the source of water to 

wells for a small area in the Coastal Plain may be 

significantly different than these regional estimates.

Flow near the centers of four major cones of depression in aquifers was quantified for prepumping and 

January 1, 1978, (pumping period 8) conditions. The 

cones of depression are in the Potomac-Raritan-Magothy 

aquifers (Al, A2, and A3) in central Camden County, the 

middle Potomac-Raritan-Magothy aquifer (A2) in Monmouth and Middlesex Counties, the Englishtown and 

Wenonah-Mount Laurel aquifers (A4 and A5) in Monmouth and Ocean Counties, and the confined Kirkwood 

aquifer (A8) in Atlantic County. The areas for which 

ground-water flow budgets were compiled are shown in 

figure 25. These areas include a large percentage of local 

withdrawals within relatively small areas as compared to 

the areas of the cones of depression. The areas were 

selected because the previously discussed analysis of 

transient conditions indicated that simulated water levels within these areas are near steady state.

The rate of water released from storage at a particular 

time is not easily estimated from simulation results. The 

rate of water being released from aquifer storage during 

the last time step of any pumping period is much smaller 

than the actual rate as illustrated by the very small 

simulated water-level changes during the last time step 

of many pumping periods (figs. 52-54). The average rate 

of water released from storage during an entire pumping 

period is a better estimate of the actual rate of water

being released from storage at the end of a pumping 

period. However, the average rate for a pumping period 

increases the budget error between discharges and sources of water estimated at the end of a pumping period.

Ground-water flow budgets were calculated for areas 

near the center of the major cones of depression, which 

are close to steady-state conditions and where water 

being released from aquifer storage is negligible. The 

simulated release of water from aquifer storage at the 

end of pumping period 8, January 1, 1978, is considered 

insignificant and is not included in the following analysis 

of source of water to wells for these selected areas. 

Estimates of the actual rate of water released from 

storage at January 1, 1978, based on the rate of water 

released from storage during pumping period 8 (January 

1,1973, to January 1,1978), are less than 2 percent of the 

discharges from these areas. The following analysis 

compares the relative significance of changes in the rates 

of horizontal and vertical flows as a source of water to 

wells in these areas. The importance of aquifer storage as 

a source of water to wells is discussed for each aquifer 

and pumping period later in this section.

The prepumping and January 1, 1978, horizontal and 

vertical flow rates are shown in figures 88 to 91 for each 

area. Under prepumping conditions, the major direction 

of flow into the budget areas for the Potomac-RaritanMagothy aquifers (Al, A2, and A3) in central Camden 

County was from above (fig. 88). A major direction of 

outflow for these aquifers under prepumping conditions 

was updip toward the outcrop areas to the northwest. 

For the middle and upper Potomac-Raritan-Magothy 

aquifers in the central Camden County area, another 

major direction of outflow was downward. For the 

middle Potomac-Raritan-Magothy aquifer in Middlesex 

and Monmouth Counties (fig. 89), the major direction of 

inflow under prepumping conditions is from the southwest, and the major direction of outflow is updip (northwest) toward the outcrop. Unlike the Potomac-RaritanMagothy aquifers, the major direction of prepumping 

flow into the Englishtown aquifer (A4), Wenonah-Mount 

Laurel aquifer (A5), and the confined Kirkwood aquifer 

(A8) is downdip from the northwest (figs. 90 and 91).

Flow rates for January 1, 1978, are much different 

from prepumping flow rates for each of the areas. The 

major outflows from the areas are withdrawals from 

wells, except in the Wenonah-Mount Laurel aquifer (A5) 

(fig. 90), in which vertical flow downward into the 

Englishtown aquifer (A4) is the major outflow from the 

budget area. The central Camden County area for the 

middle Potomac-Raritan-Magothy aquifer (A2) is the 

only other budget area that has flow out of the area in 

addition to withdrawals. In this area, there is also 

vertical flow to the overlying and underlying aquifers. 

Flow into each of the budget areas, except in the
SIMULATION OF GROUND-WATER FLOW H127

LOWER POTOMAC-RARITAN-MAGOTHY 

AQUIFER (A1)

WITHDRAWALS

HORIZONTAL FLOW 

FROM OR TO THE: Northwest

Southwest

Northeast

Southeast

VERTICAL FLOW

.

j \

\

10

<

nc. uveiiymy 

aquifer

1 \V ' ' '

r1

-9 -3-2-10123

 OUTFLOW '""'' "' 

FLOW, IN MILLION GALLONS PER

4 5

v 

DAY

6

>

EXPLANATION

I I PREPUMPING 

I I FLOW

^^m JANUARY 1, 1978,

*FLOW BUDGET 

MODEL UNIT: ROWS: COLUMNS: 

A1 5-11 18-26

SOURCES

Increased horizontal 

inflow

Decreased horizontal 

outflow

TOTAL

DISCHARGES

Withdrawals

Increased vertical 

outflow

TOTAL

MILLION 

GALLONS 

PER DAY

8.80

1.35

10.15

9.44

0.72

10.16

PERCENT 

OF 

DISCHARGES

86.6

13.3

99.9

*Flow budget area is shown in figure 25.

FIGURE 88. Simulated prepumping and January 1, 1978, flow 

rates and source of water to wells for the Potomac-RaritanMagothy aquifers (model units Al, A2, and A3), central Camden 

County area.

MIDDLE POTOMAC-RARITAN-MAGOTHY 

AQUIFER (A2)

i i \\ i r

WITHDRAWALS

HORIZONTAL FLOW 

FROM OR TO THE: Northwest

Southwest

Northeast

Southeast

VERTICAL FLOW 

FROM OR TO THE: Overlying 

aquifer

Underlying 

aquifer

-11 -10 -2 -1 

< OUTFLOW 

FLOW, IN MILLION GALLONS PER DAY

EXPLANATION

JANUARY 1,1978, 

FLOW

*FLOW BUDGET 

MODEL UNIT: ROWS: COLUMNS: 

A2 5-11 18-26

SOURCES

Increased horizontal 

inflow

Decreased horizontal 

outflow

TOTAL

DISCHARGES

Withdrawals

Increased vertical 

outflow

Decreased vertical 

inflow

TOTAL

MILLION 

GALLONS 

PER DAY

11.70

1.35

13.05

10.59

0.88

1.60

13.07

PERCENT 

OF 

DISCHARGES

89.6

10.3

99.9

*Flow budget area is shown in figure 25. 

FIGURE 88.-Continued.

Englishtown aquifer, is greatest, 40 to 75 percent of the 

total flow, from the northwest (downdip from the outcrop 

areas). In the Englishtown aquifer in Monmouth and 

Ocean Counties, about 40 percent of the flow into the 

area is from the northwest, but about 47 percent of the

flow enters the area from the overlying Wenonah-Mount 

Laurel aquifer. Other significant flows into the budget 

areas occur in the central Camden County area for the 

upper Potomac-Raritan-Magothy aquifer, where 27 per 

cent of the flow into the area is from the overlying
H128 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

UPPER POTOMAC-RARITAIM-MAGOTHY 

AQUIFER (A3)

MIDDLE POTOMAC-RARITAN-MAGOTHY 

AQUIFER (A2)

WITHDRAWALS

HORIZONTAL FLOW 

FROM OR TO THE: Northwest

VERTICAL FLOW 

FROM OR TO THE: Overlying 

aquifer

Underlying 

aquifer

-24

WITHDRAWALS

HORIZONTAL FLOW 

FROM OR TO THE: Northwest

Southwest

Northeast

Southeast

VERTICAL FLOW 

FROM OR TO THE: Overlying 

aquifer

-15 -14 -2-101 

"< OUTFLOW 

2345 

- INFLOW 

-3 -2 -1 0 

 OUTFLOW 

FLOW, IN MILLION GALLONS PER DAY

FLOW, IN MILLION GALLONS PER DAY

EXPLANATION

EXPLANATION

PREPUMPING 

FLOW

JANUARY 1,1978, 

FLOW

PREPUMPING 

FLOW

JANUARY 1,1978, 

FLOW

*FLOW BUDGET 

MODEL UNIT: ROWS: COLUMNS: 

A3 5-11 18-26

SOURCES

Increased horizontal 

inflow

Decreased horizontal 

outflow

Increased vertical 

inflow

Decreased vertical 

outflow

TOTAL

DISCHARGES

Withdrawals

TOTAL

MILLION 

GALLONS 

PER DAY

14.97

1.49

5.81

1.60

23.87

24.00

24.00

PERCENT 

OF 

DISCHARGES

62.4

6.2

24.2

6.7

99.5

*FLOW BUDGET 

MODEL UNIT: ROWS: COLUMNS: 

A2 4-6 42-^45

SOURCES

Increased horizontal 

inflow

Decreased horizontal 

outflow

Increased vertical 

inflow

Decreased vertical 

outflow

TOTAL

DISCHARGES

Withdrawals

TOTAL

MILLION 

GALLONS 

PER DAY

12.57

1.05

0.50

0.06

14.18

14.28

14.28

PERCENT 

OF 

DISCHARGES

88.0

7.4

3.5

0.4

99.3

"Flow budget area is shown in figure 25. 

FIGURE 88. Continued.

*Flow budget area is shown in figure 25.

FIGURE 89. Simulated prepumping and January 1, 1978, flow 

rates and source of water to wells for the middle PotomacRaritan-Magothy aquifer (model unit A2), Middlesex and 

Monmouth Counties.

Englishtown aquifer, and in the Middlesex and Monmouth County area for the middle Potomac-RaritanMagothy aquifer, where 35 percent of the flow into the 

area is from the southwest (southwestern Middlesex 

County).

The major source of water to wells, the difference 

between prepumping and January 1, 1978, inflows and 

outflows, is increased horizontal inflow into the budget 

areas (figs. 88-91). This flow is 79 to 90 percent of the 

total flow to wells in five of the seven areas. In the
SIMULATION OF GROUND-WATER FLOW H129

ENGLISHTOWN AQUIFER (A4) WENONAH-MOUNT LAUREL AQUIFER (A5)

WITHDRAWALS

HORIZONTAL FLOW 

FROM OR TO THE: Northwest

Southwest

Northeast

Southeast

VERTICAL FLOW 

FROM OR TO THE: Overlying 

aquifer

Underlying 

aquifer

i i i r 

WITHDRAWALS

HORIZONTAL FLOW 

FROM OR TO THE: Northwest

Southwest

Northeast

Southeast

VERTICAL FLOW 

FROM OR TO THE: Overlying 

aquifer

-8 -7 -1 

< OUTFLOW -

234 

INFLOW > 

Underlying

aquifer j

i i i i 1 1 1 1

-4-3-2-10 1 2 34

FLOW, IN MILLION GALLONS PER DAY FLOW, IN MILLION GALLONS PER DAY

EXPLANATION EXPLANATION

JANUARY 1,1978, 

FLOW

JANUARY 1,1978, 

FLOW

*FLOW BUDGET 

MODEL UNIT: ROWS: COLUMNS: 

A4 12-17 37-46

SOURCES

Increased horizontal

inflow

Decreased horizontal 

outflow

Increased vertical 

inflow

Decreased vertical 

outflow

TOTAL

DISCHARGES

Withdrawals

TOTAL

MILLION 

GALLONS 

PER DAY

3.80

0.34

3.80

0.02

7.96

7.97

7.97

PERCENT 

OF 

DISCHARGES

47.7

4.2

47.7

0.3

99.9

*FLOW BUDGET 

MODEL UNIT: ROWS: COLUMNS: 

A5 12-17 37-46

SOURCES

Increased horizontal 

inflow

Decreased horizontal 

outflow

Increased vertical 

inflow

TOTAL

DISCHARGES

Withdrawals

Increased vertical 

outflow

TOTAL

MILLION 

GALLONS 

PER DAY

3.61

0.22

0.73

4.56

0.90

3.69

4.59

PERCENT 

OF 

DISCHARGES

78.7

4.8

15.8

99.3

*Flow budget area is shown in figure 25. *Flow budget area is shown in figure 25.

FIGURE 90. Simulated prepumping and January 1, 1978, flow rates and source of water to wells for the Englishtown and Wenonah-Mount

Laurel aquifers (model units A4 and A5), Ocean and Monmouth Counties.

central Camden County area for the upper PotomacRaritan-Magothy aquifer (A3), increased horizontal 

inflow is 62 percent of the total flow to wells, and in the 

Monmouth-Ocean County area for the Englishtown aquifer (A4), this source is 48 percent of the total. The other 

major source of water to wells in these two areas is

increased vertical inflow. Most of the increased horizontal inflow into each of the areas is from the northwest, 

water moving downdip from the outcrop areas. 

Decreases in horizontal and vertical outflows from the 

budget areas are about 0 to 13 percent of the total flow 

of water to wells. For the Potomac-Raritan-Magothy
H130 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

CONFINED KIRKWOOD AQUIFER (A8)

WITHDRAWALS

HORIZONTAL FLOW 

FROM OR TO THE: Northwest

Southwest

Northeast

Southeast

VERTICAL FLOW 

FROM OR TO THE: Overlying 

aquifer

n i i i i i

Underlying 1 

aquifer I

i i \\ i i 1 i

11 -10 ^ -2 -1 0 1

I I i

234

1 i

5 6

»-

FLOW, IN MILLION GALLONS PER DAY

EXPLANATION

JANUARY 1,1978, 

FLOW

*FLOW BUDGET 

MODEL UNIT: ROWS: COLUMNS: 

A8 20-24 17-25

SOURCES

Increased horizontal 

inflow

Decreased horizontal 

outflow

Increased vertical 

inflow

Decreased vertical 

outflow

TOTAL

DISCHARGES

Withdrawals

TOTAL

MILLION 

GALLONS 

PER DAY

8.63

0.61

1.29

0.35

10.88

10.89

10.89

PERCENT 

OF 

DISCHARGES

79.3

5.6

11.8

3.2

99.9

*Flow budget area is shown in figure 25.

FIGURE 91. Simulated prepumping and January 1, 1978, flow 

rates and source of water to wells for the confined Kirkwood 

aquifer (model unit A8), Atlantic County.

aquifers (Al, A2, and A3) in the central Camden County 

area, the decrease in horizontal outflow is the elimination 

of prepumping flow toward the outcrop areas. In the 

Middlesex and Monmouth County area for the middle 

Potomac-Raritan-Magothy aquifer (A2), the decrease in

horizontal outflow is the elimination of prepumping flow 

toward the outcrop area and Raritan Bay. In the 

Englishtown (A4), Wenonah-Mount Laurel (A5), and the 

confined Kirkwood (A8) aquifers, the decrease in horizontal outflow from the budget areas constitutes the 

elimination of prepumping flow toward offshore discharge areas to the northeast, southeast, and southwest.

The total amount of water released from storage 

within all the aquifers was analyzed for each pumping 

period, and the amount of water released from storage 

within each aquifer was analyzed for pumping period 8 

(1973 to 1978) and for prepumping conditions (1896) 

through pumping period 8 (1978). Table 12 shows the 

simulated source of water to wells for each pumping 

period and includes the rate of water released from 

storage and the percentage of withdrawals that comes 

from water released from storage for each pumping 

period. The rate of water released from storage near the 

end of the simulation (pumping periods 7 to 9, 1968 to 

1980) is about 10 Mgal/d or 3 percent of the withdrawals 

during that time. The highest rates of water released 

from storage, 13 Mgal/d, were during the late 1960's 

(pumping period 6,1965 to 1968) or about 5 percent of the 

withdrawals during that period. The simulated rates of 

water released from aquifer storage for each aquifer are 

shown in table 13. The rates for 1896 to 1978 (pumping 

periods 1 through 7) and 1973 to 1978 (pumping period 8) 

show about the same relative rates among aquifers. The 

highest rates of water released from storage ranged from 

about 1.4 to 3.0 Mgal/d and are from the PotomacRaritan-Magothy aquifers (Al, A2, and A3) and the 

upper Kirkwood-Cohansey aquifer (A9). About 80 percent of the water being released from storage at any time 

is from these aquifers.

The amount of withdrawals derived from changes in 

boundary flows is similar to the amount derived from 

storage and is also shown on table 12. The amount of 

water flowing to wells is the difference between the 

boundary flows for any pumping period and prepumping 

conditions (table 10). Near the end of the simulation 

(during pumping periods 8 and 9), changes in boundary 

flows provided about 10 Mgal/d to wells or about 

3 percent of the withdrawals. Of this 10 Mgal/d, about 

8.5 Mgal/d is from change in flow rates along the northeast boundary, about 0.9 Mgal/d is from the southwest 

boundary, and about 0.6 Mgal/d is from the southeast 

boundary (table 10). The major source of water from 

boundary flows is from increased flow into the model 

area along the northeast boundary in the middle and 

upper Potomac-Raritan-Magothy aquifers (A2 and A3) 

and the southwest boundary in the middle PotomacRaritan-Magothy aquifer (A2) and the upper KirkwoodCohansey aquifer (A9) (table 10). Not all changes in 

boundary flows were increased inflow over the period
SIMULATION OF GROUND-WATER FLOW H131

TABLE 12. Simulated source of water to wells for each pumping period

Amount of withdrawals from:

Pumping 

period End date Withdrawals Storage

Mgal/d Percent

Boundary flows Ocean and bays ___Streams 

Mgal/d Percent Mgal/d Percent Mgal/d

Error 

(Mgal/d) 1

Percent

1

2

3

4

5

6

7

8

9

1-1-1921

1-1-1946

1-1-1953

1-1-1958

1-1-1965

1-1-1968

1-1-1973

1-1-1978

1-1-1981

26.4

86.0

150.8

174.8

234.9

274.0

325.6

350.9

358.2

0.8

1.6

5.8

5.2

9.0

13.3

11.3

9.7

10.1

3.0

1.9

3.8

3.0

3.8

4.9

3.5

2.8

2.8

0.0

.3

.9

2.5

4.0

6.0

7.9

9.9

10.3

0.0

.3

.6

1.4

1.7

2.2

2.4

2.8

2.9

1.1

3.1

5.0

6.4

9.2

10.3

13.0

14.7

15.0

4.2

3.6

3.3

3.7

3.9

3.8

4.0

4.2

4.2

24.6

81.1

139.1

160.7

212.8

244.4

293.5

316.6

322.9

93.2

94.2

92.2

91.9

90.6

89.2

90.1

90.2

90.1

0.1

.1

.0

.0

.1

.0

.1

.0

.1

1 Mgal/d: million gallons per day.

TABLE IS. Simulated rate of water released from aquifer storage for each aquifer

[Pumping periods 1 through 8 are from January 1, 1896, to January 1, 1978. Pumping period 8 is from January 1, 1973, to January 1, 1978. Mgal/d: million gallons

per day.]

Model 

unit

Al

A2

A3

A4

A5

A6

A7

A8

A9

A10

Water from storage (Mgal/d)

Aquifer Pumping periods 

1 through 8

Lower Potomac-Raritan-Magothy

Middle Potomac-Raritan-Magothy

Upper Potomac-Raritan-Magothy

Englishtown

Wenonah-Mount Laurel

Vincentown

Piney Point

Lower Kirkwood Cohansey and confined Kirkwood

Upper Kirkwood-Cohansey

Holly Beach

Totals

0.36

.89

1.08

.23

.30

.07

.08

.20

.81

.00

4.02

Pumping period 8

1.39

2.93

1.73

.49

.69

.23

.18

.49

1.50

.00

X 9.63

Withdrawals Percent of 

pumping period 8 withdrawals from 

(Mgal/d) storage pumping period 8

74.40

92.31

84.11

11.86

4.47

0.95

1.97

36.91

43.82

.01

1350.81

1.87

3.17

2.06

4.13

15.44

24.21

9.14

1.33

3.42

.00

22.75

1 Totals differ slightly from values in table 13 because of rounding errors in different methods of calculation.

2 Percent of total withdrawals from storage in all aquifers for pumping period 8 (not a column total but calculated on the basis of total water from storage and total 

withdrawals for pumping period 8).

of simulation. Seven aquifers (the lower and upper 

Potomac-Raritan-Magothy, Englishtown, WenonahMount Laurel, Vincentown, and the lower KirkwoodCohansey and confined Kirkwood aquifers) have 

decreased inflow or increased outflow along the southwest boundary. The major flow out of the model area in 

1978 (pumping period 8) is 1.2 Mgal/d from the Piney 

Point aquifer (A7) toward Delaware.

The source of water to wells was also analyzed to 

determine the relative amounts of flow from local and 

regional surface-water bodies. The distinction between 

local and regional was based on the size of the surfacewater body relative to the cell size. Streams including 

the Delaware River, which are less than a cell in width, 

are considered to be local surface-water bodies. The 

Atlantic Ocean, Delaware Bay, and Raritan Bay are 

regional surface-water bodies. The areas of local and 

regional surface-water bodies are shown in figure 25.

The amount of flow to streams and rivers relative to 

the ocean and bays was determined by totaling the rate 

of flow for constant-head nodes representing streams 

and totaling those representing the ocean and bays for 

each pumping period (table 14). The simulated amount of 

flow to streams at any time is dependent on the amount 

of recharge used in the model and is not directly comparable to the amount of flow to constant-head nodes in the 

bays and ocean or to withdrawals. However, the change 

in flow to rivers and streams from prepumping conditions 

to any pumping period is not dependent on recharge but 

is determined by withdrawals., as is the change in flow to 

the ocean and bays. Therefore, the amount of withdrawals from changes in flow to streams relative to changes in 

flow to the ocean and bays was determined by comparing 

(1) the amount of withdrawals to (2) changes from 

prepumping conditions in the flow rates to constant-head 

nodes representing each source (table 12).
H132 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

TABLE 14. Simulated flow to and from constant-head nodes for each 

pumping period

[Flow to and from constant-head nodes: Positive flows are into constant-head 

nodes, negative flows are out of constant-head nodes. Difference between flows 

for any pumping period and prepumping flows is the source of water to wells in 

table 13.

Streams: Flow to stream constant-head nodes is directly dependent on simulated 

recharge to the water-table aquifer, 20 inches per year (4507 million gallons per 

day).]

Pumping 

period End date

Flow to and from constant-head nodes 

(million gallons per day)

Ocean and bays Streams

prepumping

1

2

3

4

5

6

7

8

9

1-1-1896

1-1-1921

1-1-1946

1-1-1953

1-1-1958

1-1-1965

1-1-1968

1-1-1973

1-1-1978

1-1-1981

12.7

11.6

9.6

7.7

6.3

3.5

2.4

-.3

-2.0

-2.3

4489.8

4465.2

4408.7

4350.7

4329.1

4277.0

4245.4

4196.3

4173.2

4166.9

In general, throughout the simulation, the rates of 

flow to wells from the ocean and bays are slightly more 

than flow to wells from storage or lateral boundary flows. 

Flow from the ocean and bays is about 14 Mgal/d near the 

end of the simulation, or about 4 percent of withdrawals. 

The major source of water to wells is from decreased 

streamflow. Streamflow provides about 320 Mgal/d or 90 

percent of withdrawals. Decreased streamflow is equivalent to increased deep percolation to the confined aquifers. Based on data in table 14 and on the area of local 

surface-water bodies on figure 25, deep percolation 

increased from 0.1 in/yr during prepumping conditions to 

about 1.5 in/yr near the end of the simulation (pumping 

periods 8 and 9, 1978 to 1981).

SUMMARY AND CONCLUSIONS

Flow in the interbedded unconsolidated sand, silt, and 

clay of the New Jersey Coastal Plain was simulated with 

a digital model representing an alternating sequence of 

10 aquifers and 9 intervening confining units. These units 

generally thicken downdip from the Fall Line toward the 

Atlantic Ocean. Near the Fall Line, aquifers and confining units are less than 50 feet thick. In downdip freshwater areas, maximum aquifer thicknesses range from 

about 100 to 600 feet, and maximum confining-unit 

thicknesses range from about 50 to 1,000 feet.

The prepumping ground-water flow system was 

recharged in upland areas of high altitudes in Mercer, 

Middlesex, and western Monmouth Counties; in western 

Ocean and central Burlington Counties; and in central 

Gloucester and Camden Counties and was discharged to 

the Atlantic Ocean, Delaware River, Delaware Bay,

Raritan Bay, and large rivers in the Coastal Plain. A 

large part of ground-water recharge was discharged to 

nearby surface-water bodies, and only a small amount 

recharged the confined aquifers. Recharge to the confined aquifers during prepumping conditions flowed vertically downward through confining units and laterally 

downdip in aquifers, then upward through confining 

units or sometimes laterally updip in aquifers to be 

discharged to the regional surface-water bodies.

Under pumping conditions, regional cones of depression formed in the three Potomac-Raritan-Magothy aquifers, Englishtown aquifer, Wenonah-Mount Laurel aquifer, and the confined Kirkwood aquifer. In 1980, 

withdrawals were greater than 350 Mgal/d. The sources 

of water to wells include water released from aquifer 

storage and decreased discharge to large surface-water 

bodies but mostly water from reduction in streamflow.

Water levels in the 10 aquifers were simulated by 

using a multilayer finite-difference model for prepumping steady-state conditions and transient conditions from 

1896 to 1980. The model included 10 aquifer layers, a grid 

with 29 rows and 51 columns, with cell sizes ranging from 

6.25 to 47.5 mi2 . Calibration was achieved primarily by 

trial-and-error adjustment of initial estimates of transmissivities and vertical leakance of the confining units. 

Minor adjustments were made to water-table and stream 

altitudes and the confined aquifer storage coefficient. 

After calibration, the model was tested for sensitivity to 

several aquifer and confining-unit properties and several 

boundary conditions.

The lower model boundary and the northwestern 

aquifer limits are no-flow boundaries. The other lateral 

boundaries are flow or no-flow boundaries depending on 

whether an aquifer extends beyond the modeled area. 

Downdip no-flow boundaries represent either the limits 

of the aquifers or a freshwater-saltwater interface at the 

estimated location of 10,000 mg/L chloride concentrations within the aquifers. Flows for the lateral flow 

boundaries were calculated from simulated water-level 

and transmissivity data from the regional RASA model 

of the northern Atlantic Coastal Plain.

Flow was simulated in the 10 aquifers by using a 

10-layer model with a constant-head boundary representing water-table altitudes and an 11-layer model with 

recharge of 20 in/yr to the water table and with a 

constant-head boundary representing altitudes of longterm stream stages. Simulations with the 10-layer model 

provided estimates of deep percolation to the confined 

aquifers, which were used to calculate streambed vertical leakance between the water table and stream nodes. 

The upper 11-layer model boundary allows simulated 

water levels in the water-table aquifer to change in 

response to withdrawals but provides an infinite source 

of water from overlying streams.
SUMMARY AND CONCLUSIONS H133

Model calibration is partly based on a comparison of 

simulated to interpreted potentiometric surfaces and of 

simulated to actual well hydrographs. Differences 

between simulated and measured water levels are usually less than 15 feet. However, in some areas aquifers 

are not considered calibrated. Generally, these are offshore areas, where there are no measured water levels 

for calibration, and in outcrop areas where the cell size is 

large compared to outcrop widths. Downdip areas of the 

three Potomac-Raritan-Magothy aquifers (Al, A2, and 

A3) in Monmouth and Ocean Counties and the Piney 

Point aquifer (A7) in Cumberland County are not well 

calibrated, as simulated water levels are more than 15 

feet higher than measured water levels. Although areas 

near the major cones of depression are considered calibrated, simulated water levels near the center of the 

cones are 10 to 40 feet higher than measured water levels 

because of the large cell size.

Model calibration is also based on whether simulated 

flow to and from constant-head nodes is reasonable in 

relation to recharge and discharge areas postulated in 

the conceptual model. Areas of simulated recharge to the 

confined aquifers coincide with areas of high land-surface 

altitudes, and discharge areas coincide with low altitude 

areas along large surface-water bodies. Highest simulated flow rates to and from the confined aquifers and 

between the water table and streams are in areas where 

there is no confining unit underlying the aquifers' outcrops. In areas where confining units underlie the unconfined outcrops, simulated recharge and discharge rates 

to the confined aquifers are generally less than 1.5 in/yr, 

and recharge and discharge to streams is generally 

within 3.5 in/yr of the assumed recharge rate of 20 in/yr. 

Under pumping conditions, simulated flow to streams 

decreased less than 5 in/yr in most areas. Simulated deep 

percolation to the confined aquifers from the unconfined 

outcrop areas is 0.1 in/yr under prepumping conditions 

and 1.5 in/yr under pumping conditions.

The calibrated model provided regional estimates of 

aquifer transmissivity and confining-unit vertical leakance as shown in table 8. The highest transmissivity, 

greater than 10,000 ft2/d, is in Camden and Gloucester 

Counties in the Potomac-Raritan-Magothy aquifers (Al, 

A2, and A3); in Monmouth and Ocean Counties in the 

middle Potomac-Raritan-Magothy aquifer (A2); in Atlantic and Cape May Counties in the confined Kirkwood 

aquifer (A8); and in Ocean, Burlington, Atlantic, and 

Cape May Counties in the lower and upper KirkwoodCohansey aquifers (A8 and A9). Leakance is highest, 

greater than lxlO~3 (ft/d)/ft, in updip areas near the 

outcrops and lowest, less than 1 x 10~5 (ft/d)/ft, in downdip areas. The model was calibrated by using a specific 

yield of 0.15 in unconfined areas. A storage coefficient of 

lxlO~4 was used for all the confined aquifers except in

downdip areas of Monmouth and Ocean Counties for the 

Potomac-Raritan-Magothy aquifers (Al, A2, and A3) 

where storage coefficients of 5xlO~4 to 8xlO~4 were 

used.

In the simulated prepumping flow system, vertical 

hydraulic gradients between aquifers are highly variable 

but tend to be greatest in updip areas. Simulated prepumping vertical flow rates are also highest, up to about 

4 in/yr, in updip areas compared to rates of less than 0.2 

in/yr in downdip areas. In the simulated 1978 transient 

flow system, steepest vertical and lateral hydraulic gradients are near the major cones of depression. Lateral 

gradients are steepest on the updip and onshore sides of 

the cones. Flow rates between aquifers in 1978 are less 

than 0.2 in/yr in many areas, but rates from about 1 to 5 

in/yr are common locally in updip areas and near large 

cones of depression.

Sensitivity simulations show that in the major cones of 

depression tested, simulated water levels are fairly 

sensitive to changes in transmissivity and confining-unit 

leakance. Sensitivity simulations also show that the 

simulated water levels near the center of the cone in 

Camden County are most sensitive to confining-unit 

vertical leakance near the outcrop areas of the PotomacRaritan-Magothy aquifers (Al, A2, and A3). Simulated 

water levels in the cone of depression near Atlantic City 

are sensitive to changes in transmissivity in the confined 

Kirkwood aquifer (A8) along the updip extent of the 

overlying confining unit, where the aquifer becomes 

unconfined. Sensitivity analyses also indicate that the 

aquifer storage coefficients used in the calibrated model 

were reasonable.

Sensitivity analysis also indicated that simulated 

water levels in most areas with measured water-level 

data were not very sensitive to the position of the 

aquifers' no-flow boundaries or to the amount of flow at 

the flow boundaries. The location of the downdip aquifer 

limits, the location of the freshwater-saltwater interface, 

and the amount of flow at the lateral flow boundaries are 

reasonable approximations of the physical system and 

have minimal effects on estimates of transmissivity and 

vertical leakance. However, in Monmouth and Ocean 

Counties in the Englishtown aquifer (A4), water levels 

are sensitive to the position of the downdip limit of the 

Englishtown aquifer and to the position of the offshore 

limit of the upper sand unit within the aquifer. The 

location of these limits should be better defined for more 

accurate simulation in these areas.

Sensitivity analyses of confining-unit storage show 

that a preliminary estimate of 6xlO~6 per foot for 

specific storage is probably reasonable. However, aquifer storage should be based on aquifer-specific storage 

and thickness for better simulation of the flow system.
H134 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

Analysis of flow near the downdip aquifer boundaries 

indicates some vertically downward flow under prepumping conditions in the lower and middle PotomacRaritan-Magothy aquifers (Al and A2) and in the 

Englishtown aquifer (A4). Although simulated water 

levels within the aquifers near the freshwater-saltwater 

interface boundary cannot be used to calculate movement of the interface, the lower Potomac-RaritanMagothy aquifer (Al) and the confined Kirkwood aquifer 

(A8) have the greatest potential for inland migration of 

saltwater.

Analysis of transient conditions showed that the flow 

system is very near steady-state conditions near the 

center of the major cones of depression. Water levels in 

these areas would change less than 5 feet if withdrawal 

rates remained at the 1978-80 rates. However, in downdip areas farther from the major cones of depression, the 

flow system is more transient, and water levels would 

decline as much as 25 feet if there were no change in 

withdrawal rates after 1980. If there were no withdrawals after 1980, water levels near the major cones would 

recover quickly 95 percent in 2 to 6 years but water 

levels farther from the cones would recover more 

slowly 75 percent in 12 to 16 years.

The major source of water to wells near the center of 

the major cones of depression in 1978 is increased lateral 

flow from the outcrop areas. In the upper PotomacRaritan-Magothy aquifer (A3) and the Englishtown aquifer (A4), another major source of water is increased 

vertical flow through the overlying confining units. 

About 80 percent of the water released from storage is 

from the Potomac-Raritan-Magothy aquifers (Al, A2, 

and A3) and the upper Kirkwood-Cohansey aquifer (A9). 

On a regional scale, the simulated sources of water to 

wells in the late 1970's include (1) 3 percent from aquifer 

storage, (2) 3 percent from boundary flows, (3) 4 percent 

from the ocean and bays, and (4) 90 percent from 

decreased discharge to or increased recharge from 

streams.

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Anderson, H.R., and Appel, C.A., 1969, Geology and ground-water 

resources of Ocean County, New Jersey: New Jersey Department 

of Conservation and Economic Development, Division of Water 

Policy and Supply, Special Report 29, 93 p.

Back, William, 1966, Hydrochemical facies and ground-water flow 

patterns in the northern part of the Atlantic Coastal Plain 

Hydrology of aquifers systems: U.S. Geological Survey Professional Paper 498-A, 42 p.

Barksdale, H.C., Greenman, D.W., Lang, S.M., Hilton, G.S., and 

Outlaw, D.E., 1958, Ground-water resources in the tri-state 

region adjacent to the lower Delaware River: New Jersey Department of Conservation and Economic Development, Special Report 

13, 190 p.

Barksdale, H.C., Johnson, M.E., Schaefer, E.J., Baker, R.C., and 

DeBuchananne, G.D., 1943, The ground-water supplies of Middlesex County, New Jersey: New Jersey State Water Policy Commission, Special Report 8, 160 p.

Clark, G.A., Meisler, Harold, Rhodehamel, E.G., and Gill, H.E., 1968, 

Summary of ground-water resources of Atlantic County, New 

Jersey, with special reference to public water supplies: New 

Jersey Department of Conservation and Economic Development, 

Water Resources Circular 18, 53 p.

Gushing, E.M., Kantrowitz, I.H., and Taylor, K.R., 1973, Water 

resources of the Delmarva Peninsula: U.S. Geological Survey 

Professional Paper 822, 58 p.

Eckel, J.A., and Walker, R.L., 1986, Water levels in major artesian 

aquifers of the New Jersey Coastal Plain, 1983: U.S. Geological 

Survey Water-Resources Investigations Report 86-4028, 62 p.

Farlekas, G.M., 1979, Geohydrology and digital-simulation model of 

the Farrington aquifer in the northern Coastal Plain of New 

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

Report 79-106, 55 p.

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.

Gill, H.E., 1959, Geology and ground-water resources of the Cape May 

Peninsula, lower Cape May County, New Jersey: New Jersey 

Department of Conservation and Economic Development, Water 

Resources Circular 1, 19 p.

Gill, H.E., 1962a, Ground-water resources of Cape May County, New 

Jersey, salt-water invasion of principal aquifers: New Jersey 

Department of Conservation and Economic Development, Special 

Report 18, 171 p.

Gill, H.E., 1962b, Records of wells, well loss, and summary of 

stratigraphy of Cape May County, New Jersey: New Jersey 

Department of Conservation and Economic Development, Water 

Resources Circular 8, 54 p.

Gill, H.E., and Farlekas, G.M., 1976, Geohydrologic maps of the 

Potomac-Raritan-Magothy aquifer system in the New Jersey 

Coastal Plain: U.S. Geological Survey Hydrologic Investigations 

Atlas, HA-557.

Greenman, D.W., Rima, D.R., Lockwood, W.N., and Meisler, Harold, 

1961, Ground-water resources of the Coastal Plain area of southeastern Pennsylvania: Pennsylvania Geological Survey Bulletin, 

4th series, W 13, 375 p.

Hardt, W.F., 1963, Public water supplies in Gloucester County, New 

Jersey: New Jersey Department of Conservation and Economic 

Development, Water Resources Circular 9, 55 p.

Hardt, W.F., and Hilton, G.S., 1969, Water resources and geology of 

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Conservation and Economic Development, Special Report 30, 

130 p.

Harbaugh, A.W., Luzier, J.E., and Stellerine, Flavian, 1980, 

Computer-model analysis of the use of Delaware River water to 

supplement water from the Potomac-Raritan-Magothy aquifer 

system in southern New Jersey: U.S. Geological Survey WaterResources Investigations Report 80-31, 41 p.

Harbaugh, A.W., and Tilley, C.L., 1984, Steady-state computer model 

of the water-table aquifer in the Mullica River basin, the Pine 

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Investigations Report 84-4295, 38 p.

Jablonski, L.A., 1959, Records of wells and ground-water quality in 

Monmouth County, New Jersey: New Jersey Department of 

Conservation and Economic Development, Water Resources Circular 2, 47 p.

 1960, Factual data for public-supply wells and selected irrigation wells in Monmouth County, New Jersey: New Jersey Depart-
REFERENCES CITED H135

ment of Conservation and Economic Development, Division of 

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-1968, Ground-water resources of Monmouth County, New

Jersey: New Jersey Department of Conservation and Economic

Development, Division of Water Policy and Supply, Special Report

23, 117 p. 

Johnston, R.H., 1976, Relation of ground water to surface water in four

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Leahy, P.P., 1976, Hydraulic characteristics of the Piney Point aquifer

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 1979, Digital model of the Piney Point aquifer in Kent County,

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No. 29, 81 p.

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confining-bed and aquifer pinchouts: U.S. Geological Survey 

Water-Resources Investigations Report 82^1023, 59 p.

Leahy, P.P., and Martin, Mary, 1986, Simulation of ground-water 

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Luzier, J.E., 1980, Digital-simulation and projection of head changes in 

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McClymonds, N.E., and Franke, O.L., 1972, Water transmitting 

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Nemickas, Bronius, and Carswell, L.D., 1976, Stratigraphic and 

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 1968, Geology and ground-water resources of Burlington 

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Survey Water-Resources Investigations Report 87-4038, 120 p.

TABLE 15
H138 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

TABLE 15. Comparison between simulated and measured water levels at the end of each pumping period

[Simulated water level: In feet above or below sea level. Estimated from simulated water levels for the three nodes nearest to actual well location. Measured water 

level: In feet above or below sea level. Date of measured water level is for measurement nearest to end date in Zapecza, Voronin, and Martin (1987, pis. 1-10). 

Water-level difference: Simulated water level minus measured water level, in feet. Well locations shown in figures 42 to 51. , data unavailable.]

Pumping 

period End date Simulated water level

Measured 

water level

Water-level 

difference

LOWER POTOMAC-RARITAN-MAGOTHY AQUIFER (Al)

WELL

1

2

3

4

5

6

7

8

9

WELL

1

2

3

4

5

6

7

8

9

WELL

1

2

3

4

5

6

7

8

9

WELL

1

2

3

4

5

6

7

8

9

WELL

1 

2

3

4

5

6

7

8

9

5-262 NODE

1/1/1921

1/1/1946

1/1/1953

1/1/1958

1/1/1965

1/1/1968

1/1/1973

1/1/1978

1/1/1981

5-645 NODE

1/1/1921

1/1/1946

1/1/1953

1/1/1958

1/1/1965

1/1/1968

1/1/1973

1/1/1978

1/1/1981

5-683 NODE

1/1/1921

1/1/1946

1/1/1953

1/1/1958

1/1/1965

1/1/1968

1/1/1973

1/1/1978

1/1/1981

7-283 NODE

1/1/1921

1/1/1946

1/1/1953

1/1/1958

1/1/1965

1/1/1968

1/1/1973

1/1/1978

1/1/1981

7-354 NODE

1/1/1921 

1/1/1946

1/1/1953

1/1/1958

1/1/1965

1/1/1968

1/1/1973

1/1/1978

1/1/1981

7,26

17.89

12.14

5.20

1.04

-12.47

-21.40

-33.02

-45.51

-48.49

5,27

16.45

12.94

8.64

5.69

-7.51

-18.38

-30.28

-40.26

-37.14

14, 30

28.76

23.94

18.46

15.66

2.16

-4.58

-14.87

-28.14

-36.60

5, 22

9.35

-1.71

-16.39

-24.94

-41.82

-49.90

-59.58

-65.19

-62.11

3,23

1.14 

-6.61

-12.24

-12.27

-12.49

-11.79

-14.59

-15.42

-14.10

_

-34.93

-45.48

-48.92

_

-15.35

-24.04

-29.39

-33.36

-3.59

-8.06

-16.36

-29.44

-31.94

_

-43.82

-51.49

-58.57

-62.09

-62.37

_

0.42

-2.14

-1.41

-2.25

-2.68

0.25

-0.41

1.91

-0.03

-0.43

_

_

-3.03

-6.24

-10.87

-3.78

5.75

3.47

1.49

1.29

-4.66

2.00

1.59

-1.01

-3.10

0.26

_

-12.67

-10.13

-11.08

-9.54

-11.92

-15.67

-13.69

Pumping 

period

Vr,A A fQ Simulated End date , , , water level

Measured 

water level

Water-level 

difference

LOWER POTOMAC-RARITAN-MAGOTHY AQUIFER (Al)-Continued

WELL

1

2

3

4

5

6

7

8

9

WELL

1

2

3

4

5

6

7

8

9

WELL

1

2

3

4

5

6

7

8

9

WELL

1

2

3

4

5

6

7

8

9

7-412 NODE

1/1/1921

1/1/1946

1/1/1953

1/1/1958

1/1/1965

1/1/1968

1/1/1973

1/1/1978

1/1/1981

7-476 NODE

1/1/1921

1/1/1946

1/1/1953

1/1/1958

1/1/1965

1/1/1968

1/1/1973

1/1/1978

1/1/1981

8,23

15.36

7.50

-2.16

-7.63

-21.81

-30.73

-41.98

-58.61

-62.75

10, 20

17.75

10.10

1.03

-3.86

-16.72

-25.05

-34.65

-46.34

-50.03

-28.30

-43.67

-59.25

-67.14

-15.87

-21.97

-31.94

-43.61

-48.96

_

-2.43

1.69

0.65

4.38

-0.85

-3.08

-2.71

-2.73

-1.07

15-296 NODE 4, 18

1/1/1921

1/1/1946

1/1/1953

1/1/1958

1/1/1965

1/1/1968

1/1/1973

1/1/1978

1/1/1981

8.62

3.14

-4.36

-8.25

-17.06

-24.68

-28.74

-29.40

-26.54

-13.12

-13.24

-13.69

-15.32

-18.84

-3.93

-11.44

-15.05

-14.07

-7.70

15^323 NODE 4, 20

1/1/1921

1/1/1946

1/1/1953

1/1/1958

1/1/1965

1/1/1968

1/1/1973

1/1/1978

1/1/1981

7.73

-0.05

-15.07

-20.06

-29.19

-34.91

-39.52

-40.86

-36.31

_

-34.47

-47.99

-60.50

-49.57

-46.14

-47.89

-47.32

MIDDLE POTOMAC-RARITAN-MAGOTHY AQUIFER

WELL 

1

3

4

n o

6

7

8

9

5-63 NODE 5

1/l/lC'iil 1/1/1Q91

1/1/1946

1/1/1953

1/1/1958

1/1/1965

1/1/1968

1/1/1973

1/1/1978

1/1/1981

,28 

15.53

13.34

10.53

8.63

0.53

-7.48

-15.20

-21.80

-21.88

-4.49

-10.03

-14.86

-18.18

19.40

27.93

31.31

14.66

6.61

7.03

11.01

(A2)

_

_

_

-2.99

-5.17

-6.94

-3.71
TABLE 15 H139

TABLE 15. Comparison between simulated and measured water levels at the end of each pumping period Continued

Pumping Simulated 

penod water level

Measured 

water level

Water-level 

difference

MIDDLE POTOMAC-RARITAN-MAGOTHY AQUIFER (A2)- Continued

WELL 5-101 NODE 4, 29

1 1/1/1921 12.28

2 1/1/1946 11.80

3 1/1/1953 10.28

4 1/1/1958 9.26

5 1/1/1965 6.82

6 1/1/1968 4.98

7 1/1/1973 4.07

8 1/1/1978 3.32

9 1/1/1981 3.22

WELL 5-261 NODE 7, 26

1 1/1/1921 18.23

2 1/1/1946 12.62

3 1/1/1953 5.84

4 1/1/1958 1.77

5 1/1/1965 -11.79

6 1/1/1968 -20.78

7 1/1/1973 -32.53

8 1/1/1978 -44.89

9 1/1/1981 -47.54

WELL 5^40 NODE 7, 30

1 1/1/1921 25.41

2 1/1/1946 21.44

3 1/1/1953 16.30

4 1/1/1958 14.65

5 1/1/1965 2.25

6 1/1/1968 -4.92

7 1/1/1973 -12.08

8 1/1/1978 -19.03

9 1/1/1981 -21.49

WELL 7-413 NODE 8, 23

1 1/1/1921 15.82

2 1/1/1946 7.65

3 1/1/1953 -2.29

4 1/1/1958 -7.84

5 1/1/1965 -22.55

6 1/1/1968 -31.87

7 1/1/1973 -44.07

8 1/1/1978 -57.07

9 1/1/1981 -60.77

WELL 11-137 NODE 17, 16

1 1/1/1921 25.75

2 1/1/1946 18.91

3 1/1/1953 12.92

4 1/1/1958 9.46

5 1/1/1965 0.27

6 1/1/1968 -5.52

7 1/1/1973 -12.25

8 1/1/1978 -20.08

9 1/1/1981 -24.48

-1.29

-0.92

-4.37

-5.02

-4.12

1.52

1.24

-35.04

-45.80

-49.13

-21.03

-28.76

-27.19

-30.43

-38.50

-52.88

-66.34

-72.14

-36.10

-40.27

11.57

10.17

10.20

10.00

8.20

1.80

1.99

2.51

0.91

1.58

_

8.95

9.73

5.70

7.88

6.63

8.81

9.26

11.36

16.03

15.80

Pumping d d Simulated 

penod water level

Measured 

water level

Water-level 

difference

MIDDLE POTOMAC-RARITAN-MAGOTHY AQUIFER (A2)- Continued

WELL 15-97 NODE 3, 18

1 1/1/1921 4.88

2 1/1/1946 2.52

3 1/1/1953 0.35

4 1/1/1958 -0.61

5 1/1/1965 -1.71

6 1/1/1968 -4.81

7 1/1/1973 -5.71

8 1/1/1978 -4.44

9 1/1/1981 -1.72

WELL 23-70 NODE 2, 41

1 1/1/1921 61.29

2 1/1/1946 61.14

3 1/1/1953 61.00

4 1/1/1958 61.00

5 1/1/1965 60.94

6 1/1/1968 60.88

7 1/1/1973 60.86

8 1/1/1978 60.84

9 1/1/1981 60.80

WELL 23-194 NODE 4, 43

1 1/1/1921 27.89

2 1/1/1946 11.66

3 1/1/1953 -19.84

4 1/1/1958 -23.46

5 1/1/1965 -32.92

6 1/1/1968 -38.04

7 1/1/1973 -56.04

8 1/1/1978 -70.80

9 1/1/1981 -71.56

WELL 23-229 NODE 4, 39

1 1/1/1921 66.47

2 1/1/1946 64.56

3 1/1/1953 62.54

4 1/1/1958 62.31

5 1/1/1965 59.83

6 1/1/1968 57.12

7 1/1/1973 53.94

8 1/1/1978 52.65

9 1/1/1981 51.83

WELL 23-243 NODE 5, 41

1 1/1/1921 43.97

2 1/1/1946 33.17

3 1/1/1953 21.41

4 1/1/1958 21.80

5 1/1/1965 16.47

6 1/1/1968 11.36

7 1/1/1973 0.34

8 1/1/1978 -8.13

9 1/1/1981 -11.93

-4.71

-5.50

-4.08

0.16

-0.83

-2.16

59.95

57.87

56.75

56.08

58.33

59.23

57.93

55.31

1.46

-33.76

-49.43

-54.04

-62.02

-70.70

-74.51

-77.34

61.89

64.27

57.18

57.11

-9.50

4.10

3.79

-0.73

-5.88

-3.61

0.44

1.19

3.13

4.25

4.86

2.56

1.63

2.91

5.49

10.20

13.92

25.97

21.11

23.98

14.66

3.70

5.78

-4.77

-10.33

-4.52

-5.28

-2.43
H140 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

TABLE 15. Comparison between simulated and measured water levels at the end of each pumping period Continued

PumpjnS End date Simulated 

period water level

Measured 

water level

Water-level 

difference

MIDDLE POTOMAC-RARITAN-MAGOTHY AQUIFER (A2)- Continued

WELL 23-270 NODE 3, 46

1 1/1/1921 6.98

2 1/1/1946 6.95

3 1/1/1953 6.91

4 1/1/1958 6.81

5 1/1/1965 6.63

6 1/1/1968 6.57

7 1/1/1973 6.53

8 1/1/1978 6.48

9 1/1/1981 6.44

WELL 25-272 NODE 7, 43

1 1/1/1921 30.93

2 1/1/1946 24.23

3 1/1/1953 14.86

4 1/1/1958 12.57

5 1/1/1965 2.90

6 1/1/1968 -2.97

7 1/1/1973 -20.53

8 1/1/1978 -34.79

9 1/1/1981 -40.03

WELL 29-19 NODE 19, 36

1 1/1/1921 29.66

2 1/1/1946 26.13

3 1/1/1953 22.84

4 1/1/1958 20.21

5 1/1/1965 9.67

6 1/1/1968 4.61

7 1/1/1973 -4.81

8 1/1/1978 -17.00

9 1/1/1981 -26.86

WELL 29-85 NODE 14, 37

1 1/1/1921 32.47

2 1/1/1946 28.81

3 1/1/1953 24.58

4 1/1/1958 22.00

5 1/1/1965 8.54

6 1/1/1968 1.54

7 1/1/1973 -8.62

8 1/1/1978 -23.57

9 1/1/1981 -37.96

WELL 33-251 NODE 6, 10

1 1/1/1921 17.97

2 1/1/1946 9.12

3 1/1/1953 2.68

4 1/1/1958 -0.43

5 1/1/1965 -11.74

6 1/1/1968 -21.69

7 1/1/1973 -20.66

8 1/1/1978 -27.78

9 1/1/1981 -34.46

3.49

5.85

3.89

3.49

0.08

-2.02

-4.57

-41.06

-50.41

_

_

9.14

0.65

-2.78

-1.49

-21.08

-27.13

-14.60

-17.71

-26.05

-26.94

3.42

0.96

2.74

3.08

6.45

8.51

11.01

6.27

10.37

-13.95

-17.65

-24.09

-7.13

-2.49

-10.83

_

_

-7.09

-2.95

-1.73

-7.52

Pumping E d d Simulated 

period water level

Measured 

water level

Water-level 

difference

UPPER POTOMAC-RARITAN-MAGOTHY AQUIFER (A3)

WELL 5-258 NODE 7, 26

1 1/1/1921 22.21

2 1/1/1946 15.96

3 1/1/1953 8.92

4 1/1/1958 3.84

5 1/1/1965 -11.66

6 1/1/1968 -19.82

7 1/1/1973 -31.37

8 1/1/1978 -43.32

9 1/1/1981 -48.93

WELL 5-274 NODE 4, 25

1 1/1/1921 14.03

2 1/1/1946 11.01

3 1/1/1953 7.41

4 1/1/1958 4.58

5 1/1/1965 -1.83

6 1/1/1968 -6.20

7 1/1/1973 -11.72

8 1/1/1978 -16.07

9 1/1/1981 -16.19

WELL 7-30 NODE 4, 21

1 1/1/1921 7.03

2 1/1/1946 -4.35

3 1/1/1953 -20.32

4 1/1/1958 -25.07

5 1/1/1965 -35.23

6 1/1/1968 -41.13

7 1/1/1973 -48.37

8 1/1/1978 -46.88

9 1/1/1981 -39.20

WELL 7-117 NODE 7, 23

1 1/1/1921 18.25

2 1/1/1946 9.42

3 1/1/1953 -0.92

4 1/1/1958 -7.44

5 1/1/1965 -27.90

6 1/1/1968 -40.34

7 1/1/1973 -55.09

8 1/1/1978 -64.81

9 1/1/1981 -70.09

WELL 7^77 NODE 10, 20

1 1/1/1921 23.60

2 1/1/1946 14.22

3 1/1/1953 3.65

4 1/1/1958 -1.64

5 1/1/1965 -15.36

6 1/1/1968 -25.42

7 1/1/1973 -38.05

8 1/1/1978 -49.00

9 1/1/1981 -55.52

-18.90

-24.67

-38.56

-50.18

-55.20

_

-15.12

-20.65

-22.23

-17.80

-20.00

-24.50

-26.54

-30.92

-23.04

-23.65

_

-44.35

-62.10

-72.74

-76.57

-28.65

-35.89

-48.06

-61.31

-68.62

7.24

4.85

7.19

6.86

6.26

3.40

4.58

6.04

-2.52

-5.07

-10.73

-14.59

-17.45

-23.84

-15.55

_

4.01

7.01

7.93

6.49

13.29

10.46

10.01

12.31

13.09
TABLE 15 H141

TABLE 15. Comparison between simulated and measured water levels at the end of each pumping period Continued

Pumping

period End dat Simulatedwater level

Measured

water level

Water-level

difference

UPPER POTOMAC-RARITAN-MAGOTHY AQUIFER (A3) -Continued

WELL

1

2

3

4

5

6

7

8

9

WELL

1 

2

3

4

5

6

7 

8 

9

WELL

1

2

3

4 

5 

6

7 

8 

9

WELL

1

2

3

4

5

6

7

8 

9

WELL

1

2

3

4

5 

6

7

8 

9

15-297

1/1/1921

1/1/1946

1/1/1953

1/1/1958

1/1/1965

1/1/1968

1/1/1973

1/1/1978

1/1/1981

23-182

1/1/1921 

1/1/1946

1/1/1953

1/1/1958

1/1/1965

1/1/1968 

1/1/1973 

1/1/1978 

1/1/1981

23-292

1/1/1921

1/1/1946

1/1/1953

1/1/1958 

1/1/1965 

1/1/1968 

1/1/1973 

1/1/1978 

1/1/1981

25-316

1/1/1921

1/1/1946

1/1/1953

1/1/1958

1/1/1965

1/1/1968

1/1/1973

1/1/1978 

1/1/1981

33-187

1/1/1921

1/1/1946

1/1/1953

1/1/1958

1/1/1965 

1/1/1968

1/1/1973

1/1/1978 

1/1/1981

NODE 4, 18

14.92

11.11

6.37

3.57

-2.76

-10.23

-12.27

-12.07

-13.47

NODE 5, 43

18.25 

17.97

17.79

17.65

17.24

17.02 

16.82 

17.02 

16.82

NODE 3, 39

76.58

76.49

76.40

76.33 

76.10 

75.92

75.68 

75.48 

75.40

NODE 9, 49

8.03

5.72

1.97

-0.34

-5.35

-5.67

-10.81

-12.98 

-12.37

NODE 6, 14

19.35

13.92

8.31

4.69

-2.34 

-7.32

-9.72

-11.88 

-12.83

-8.92

-8.48

-8.28

-10.59

-12.57

26.41

24.37

23.91

19.41

20.44 

19.52 

18.31 

16.02

78.82 

80.20 

81.48 

76.42 

75.17

-3.14

-6.46

-5.85

-7.47

-14.05 

-17.02

-18.48

-24.44 

-25.64

6.16

-1.75

-3.99

-1.47

-0.89

-8.43

-6.58

-6.26

-2.17

-3.43 

-2.71 

-1.29 

0.79

-2.72

-4.28 

-5.80 

-0.94 

0.23

-2.53

-4.35

-7.13 

-4.91

11.71 

9.70

8.76

12.56 

12.81

Pumping

period

 , j , Simulated End date , , , water level

UPPER POTOMACWELL

1

2

3

4

5

6

7

8

9

33-253

1/1/1921

1/1/1946

1/1/1953

1/1/1958

1/1/1965

1/1/1968

1/1/1973

1/1/1978

1/1/1981

Measured

water level

Water-level

difference

RARITAN-MAGOTHY AQUIFER (A3) -Continued

NODE 6, 10

14.10

9.31

5.94

5.01

2.13

-0.87

-1.74

-4.12

-6.92

-12.15

-14.45

-20.79

-22.60

11.28

12.71

16.67

15.68

ENGLISHTOWN AQUIFER (A4)

WELL 

1

LA2

oq 

4

5 

6

7 

8

9

WELL

1

2

3

4 

5 

6

7 

8

9

WELL

1

LA2

3

4

6

7 

8

9

WELL

1

2

q o

4

c o

6

7 

8

9

5-259 NODE 7, 26 

1/1/1921 4460 - -

1/1/1946

1/1/1953

1/1/1958

1/1/1965 

1/1/1968 

1/1/1973 

1/1/1978

1/1/1981

23-516

1/1/1921

1/1/1946

1/1/1953 

1/1/1958 

1/1/1965 

1/1/1968 

1/1/1973 

1/1/1978

1/1/1981

25-216

1/1/1921

1 J./ /1 J./ /1 J.I7TrU Q46

1/1/1953

1/1/1958

1/1/1965

1/1/1968

1/1/1973 

1/1/1978

1/1/1981

25-250

1/1/1921

1/1/1946

1/1/1953

1/1/1958 

1/1/1965

1/1/1968

1/1/1973 

1/1/1978

1/1/1981

43.37

40.83

37.81 

36.25 

33.99 

31.70

30.03

NODE 6, 42

90.02

89.99

89.95 

89.90

89.78 

89.74 

89.67 

89.56

89.55

NODE 7, 39

122.55

122.22

121.78

121.46

120.60

11Q QC j. j. j/. syo

118.77 

118.05

117.94

NODE 7, 42

108.61

108.18

107.53

106.20 

103.46

103.56

102.81 

101.82

101.63

20.44 

25.33 

25.95 

25.05

23.53

98.85

96.95 

95.87 

96.24 

97.64 

99.36 

97.97

94.73

_

121.48 

120.71

118.60

_

_

_

101.90 

101.26

100.29

17.37 

10.92 

8.05 

6.66

6.50

-8.86

-7.00 

-5.97 

-6.45 

-7.90 

-9.70 

-8.41

-5.18

_

-2.71 

-2.67

-0.66

_

_

0.90 

0.57

1.34
H142 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

TABLE 15. Comparison between simulated and measured water levels at the end of each pumping period Continued

Pw?^8 End date Simulated 

period water level

Measured 

water level

Water-level 

difference

ENGLISHTOWN AQUIFER (A4)- Continued

WELL 25^29 NODE 13, 41

1 1/1/1921 48.08

2 1/1/1946 31.14

3 1/1/1953 2.60

4 1/1/1958 -15.09

5 1/1/1965 -22.35

6 1/1/1968 -40.86

7 1/1/1973 -84.20

8 1/1/1978 -104.26

9 1/1/1981 -106.67

WELL 29-138 NODE 10, 35

1 1/1/1921 95.26

2 1/1/1946 92.59

3 1/1/1953 88.91

4 1/1/1958 86.95

5 1/1/1965 82.20

6 1/1/1968 77.77

7 1/1/1973 69.67

8 1/1/1978 66.48

9 1/1/1981 65.13

WELL 29-534 NODE 16, 36

1 1/1/1921 53.74

2 1/1/1946 41.86

3 1/1/1953 24.76

4 1/1/1958 15.31

5 1/1/1965 9.39

6 1/1/1968 0.74

7 1/1/1973 -30.59

8 1/1/1978 -44.24

9 1/1/1981 -47.01

-54.33

-77.46

-119.43

-135.06

-139.38

82.61

78.73

71.00

65.31

63.15

-36.64

-58.01

-73.99

-83.12

31.98

36.60

35.23

30.80

32.71

-0.41

-0.96

-1.33

1.17

1.97

_

_

37.37

27.42

29.75

36.10

WENONAH-MOUNT LAUREL AQUIFER (A5)

WELL 5-260 NODE 7, 26 

1 J. 1/1/1921 A/ ±1 ±ij£i± 48 *±O.t7rr 94

2 1/1/1946 48.52

3 1/1/1953 48.10

4 1/1/1958 47.66

5 1/1/1965 46.72 

6 1/1/1968 46.22 

7 1/1/1973 45.57 

8 1/1/1978 44.76

9 1/1/1981 44.41

WELL 5-701 NODE 8, 32

1 1/1/1921 101.24

2 1/1/1946 100.79

3 1/1/1953 99.91

4 1/1/1958 99.44

5 1/1/1965 98.01

6 1/1/1968 97.75 

7 1/1/1973 97.12 

8 1/1/1978 96.84

9 1/1/1981 97.08

50.64 

52.45 

52.12 

51.72

49.44

_

_

_

122.96

123.80 

123.04 

123.80

125.40

-3.92 

-6.23 

-6.56 

-6.96

-5.03

_

_

-24.95

-26.05 

-25.91 

-26.96

-28.31

Pumping 

period

 , , , Simulated End date , , , water level

Measured 

water level

Water-level 

difference

WENONAH-MOUNT LAUREL AQUIFER (A5)- Continued

WELL

1

2

3

4

5

6

7

8

9

WELL

1

2

3

4

5

6

7

8

9

WELL

1

2

3

4

5

6

7

8

9

WELL

1 

2

3

4

5

6

7 

8 

9

WELL

1

2

3

4

5

6

7 

8 

9

7-118 NODE 7, 23

1/1/1921 77.81

1/1/1946 77.58

1/1/1953 77.40

1/1/1958 77.25

1/1/1965 77.09

1/1/1968 76.94

1/1/1973 76.75

1/1/1978 76.43

1/1/1981 75.80

7^78 NODE 10, 20

1/1/1921 71.09

1/1/1946 67.17

1/1/1953 63.63

1/1/1958 60.93

1/1/1965 55.95

1/1/1968 49.15

1/1/1973 46.80

1/1/1978 43.87

1/1/1981 43.40

11-72 NODE 11, 9

1/1/1921 28.67

1/1/1946 24.69

1/1/1953 22.52

1/1/1958 21.06

1/1/1965 17.95

1/1/1968 15.23

1/1/1973 11.72

1/1/1978 7.85

1/1/1981 3.24

29-140 NODE 10, 35

1/1/1921 117.93 

1/1/1946 117.25

1/1/1953 116.32

1/1/1958 115.69

1/1/1965 114.61

1/1/1968 113.54 

1/1/1973 111.29 

1/1/1978 110.01 

1/1/1981 109.55

33-02 NODE 9, 12

1/1/1921 42.19

1/1/1946 39.70

1/1/1953 37.87

1/1/1958 36.59

1/1/1965 33.92

1/1/1968 31.61

1/1/1973 29.38 

1/1/1978 26.76 

1/1/1981 24.16

71.13

69.71

68.81

44.69

42.78

38.49

36.45

36.38

9.84

9.70

118.15

118.00 

117.20 

114.82 

113.18

23.08 

23.40

5.62

6.72

7.00

11.26

6.37

8.30

7.42

7.02

-1.99

-6.46

-3.54

-4.46 

-5.91 

-4.80 

-3.63

3.68 

0.77
TABLE 15 H143

TABLE 15. Comparison between simulated and measured water lei/els at the end of each pumping period Continued

Pumping 

period

 , , , Simulated End date , , , water levelMeasured 

water level

Water-level 

difference

WENONAH-MOUNT LAUREL AQUIFER (A5)- Continued

WELL

1

2

3

4

5

6

7

8

9

WELL

1

2

3

4

5

6

7

8

9

WELL

1

2

3

4

5

6

7

8

9

33-20 NODE 8, 13

1/1/1921 50.32

1/1/1946 48.96

1/1/1953 47.82

1/1/1958 47.02

1/1/1965 45.40

1/1/1968 44.05

1/1/1973 42.98

1/1/1978 41.78

1/1/1981 40.67

33-252 NODE 6, 10

1/1/1921 7.35

1/1/1946 7.57

1/1/1953 7.67

1/1/1958 6.45

1/1/1965 4.90

1/1/1968 4.81

1/1/1973 6.41

1/1/1978 7.10

1/1/1981 6.72

33-279 NODE 8, 14

1/1/1921 60.11

1/1/1946 58.53

1/1/1953 57.14

1/1/1958 56.20

1/1/1965 54.27

1/1/1968 52.54

1/1/1973 51.14

1/1/1978 49.61

1/1/1981 48.28

33.99

35.85

35.57

33.52

32.95

-1.10

1.78

0.96

0.12

_

_

46.64

47.86

47.57

44.96

44.58

11.41

8.21

7.42

8.27

7.72

_

5.92

4.63

6.14

6.60

7.63

4.68

3.57

4.65

3.70

VINCENTOWN AQUIFER (A6)

WELL

11

22

33

44

55

66

77 

88

99

29-139 NODE 10, 35

1/1/1921 121.57

1/1/1946 121.22

1/1/1953 120.73

1/1/1958 120.43

1/1/1965 119.91

1/1/1968 119.34 

1/1/1973 118.14 

1/1/1978 117.44

1/1/1981 117.27

_

_

_

_

129.95

130.40 

131.13 

131.14

129.23

_

_

_

_

-10.04

-11.06 

-12.99 

-13.70

-11.97

PINEY POINT AQUIFER (A7)

WELL

1

2

3

4

5

6

7

8

9

5-407 NODE 13, 25

1/1/1921 64.43

1/1/1946 63.02

1/1/1953 61.92

1/1/1958 60.90

1/1/1965 58.36

1/1/1968 56.52

1/1/1973 55.23

1/1/1978 53.80

1/1/1981 52.92

52.17

52.02

52.09

50.93

50.35

6.18

4.50

3.14

2.87

2.57

Pumping E d d Simulated 

period water level

Measured 

water level

Water-level 

difference

PINEY POINT AQUIFER (A7) -Continued

WELL 5-676 NODE 15, 31

1 1/1/1921 113.53

2 1/1/1946 113.29

3 1/1/1953 113.06

4 1/1/1958 112.91

5 1/1/1965 112.60

6 1/1/1968 112.38

7 1/1/1973 112.03

8 1/1/1978 111.74

9 1/1/1981 111.61

WELL 11-44 NODE 12, 12

1 1/1/1921 43.31

2 1/1/1946 40.03

3 1/1/1953 38.05

4 1/1/1958 36.49

5 1/1/1965 33.49

6 1/1/1968 30.25

7 1/1/1973 25.79

8 1/1/1978 21.92

9 1/1/1981 17.39

WELL 11-96 NODE 15, 9

1 1/1/1921 31.83

2 1/1/1946 27.89

3 1/1/1953 25.78

4 1/1/1958 23.98

5 1/1/1965 20.98

6 1/1/1968 16.86

7 1/1/1973 10.22

8 1/1/1978 4.90

9 1/1/1981 -2.21

WELL 11-163 NODE 14, 13

1 1/1/1921 41.40

2 1/1/1946 37.97

3 1/1/1953 35.93

4 1/1/1958 34.31

5 1/1/1965 31.22

6 1/1/1968 27.88

7 1/1/1973 23.10 

8 1/1/1978 19.03 

9 1/1/1981 14.30

WELL 29-18 NODE 19, 36

1 1/1/1921 26.23

2 1 l/l/iy4u /1 /1 Q/l R ZO. 9Q 77 ( (

3 1/1/1953 20.00

4 1/1/1958 18.31

5 1/1/1965 15.87

6 1/1/1968 13.93

7 1/1/1973 9.55

8 1/1/1978 4.68

9 1/1/1981 3.49

118.97

118.60

122.84

119.10

119.38

22.89

18.00

14.63

-3.44

-12.75

-18.25

21.85 

18.53

_

6.54

5.38

3.88

2.25

0.48

-6.37

-6.22

-10.81

-7.37

-7.77

2.90

3.92

2.75

13.66

17.65

16.04

-2.82 

-4.24

~

_

9.34

8.56

5.67

2.43

3.02
H144 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

TABLE 15. Comparison between simulated and measured water levels at the end of each pumping period Continued

V^yfe End date Simulated 

period water level

Measured 

water level

Water-level 

difference

PINEY POINT AQUIFER (A7) -Continued

WELL 29-425 NODE 15, 33

1 1/1/1921 121.17

2 1/1/1946 121.10

3 1/1/1953 121.00

4 1/1/1958 120.95

5 1/1/1965 120.87

6 1/1/1968 120.81

7 1/1/1973 120.66

8 1/1/1978 120.47

9 1/1/1981 120.42

_

118.60

118.72

120.62

118.83

118.33

_

2.27

2.09

0.04

1.65

2.09

LOWER KIRKWOOD-COHANSEY AQUIFER AND

CONFINED KIRKWOOD AQUIFER (A8)

WELL 1-37 NODE 22, 22

1 1/1/1921 14.87

2 1/1/1946 -5.06

3 1/1/1953 -14.03 

4 1/1/1958 -23.56 

5 1/1/1965 -38.81 

6 1/1/1968 -54.58 

7 1/1/1973 -62.40 

8 1/1/1978 -63.71

9 1/1/1981 -67.54

WELL 1-180 NODE 20, 24

1 1/1/1 LI LI LVLiL Q91 1 Lo. ft 79 (Li

2 1/1/1946 3.85

3

1 /1 /inco 1 nc l/l/195d l.Yb

4 1/1/1958 -6.25

5 1/1/1965 -15.37 

6 1/1/1968 -31.15 

7 1/1/1973 -37.35

8 1/1/1978 -37.49

9 1/1/1981 -40.93

WELL 1-366 NODE 22, 19

1 1/1/1921 14.10

2 1/1/1946 -10.57

3 1/1/1953 -22.41

4 1/1/1958 -33.47

5 1/1/1965 -46.13 

6 1/1/1968 -59.11 

7 1/1/1973 -60.25 

8 1/1/1978 -68.34

9 1/1/1981 -73.01

WELL 1-566 NODE 20, 22 

1 1/1/1921 16.74

2 1/1/1946 -4.80 

3 1/1/1953 -11.20

4 1/1/1958 -15.52

5 1/1/1965 -28.47 

6 1/1/1968 -51.44 

7 1/1/1973 -57.25 

8 1/1/1978 -55.29

9 1/1/1981 -58.50

-59.20 

-54.61 

-62.44 

-66.58 

-64.47 

-58.19

-65.17

-25.47 

-26.99 

-30.83 

-28.29

-28.75

-36.61

-51.51

-46.97

-79.65

-77.98 

-68.70 

-59.54

-53.21

-18.93 

-27.65

-19.15

-41.15 

-41.43 

-45.00 

-39.74

-39.95

45.18 

31.05 

23.64 

11.99 

2.07 

-5.52

-2.38

10.11 

-4.16 

-6.52 

-9.21

-12.17

26.04

29.10

13.50

33.53

18.87 

8.45 

-8.79

-19.80

14.13 

16.45

3.63

12.68 

-10.00 

-12.25 

-15.55

-18.54

Pumping dd Simulated 

period water level

Measured Water-level 

water level difference

LOWER KIRKWOOD-COHANSEY AQUIFER AND

CONFINED KIRKWOOD AQUIFER (A8)- Continued

WELL 1-578 NODE 21, 18

1 1/1/1921 18.71

2 1/1/1946 1.84

3 1/1/1953 -5.94

4 1/1/1958 -12.83

5 1/1/1965 -22.08

6 1/1/1968 -33.80

7 1/1/1973 -37.16

8 1/1/1978 -45.01

9

1 /I /1 Qft1 AQ 9Q i/i/iyoi ^y.^o

WELL 5-30 NODE 17, 28

1 1/1/1921 71.98

2 1/1/1946 71.97

3 1/1/1953 71.97

4 1/1/1958 71.97 

5 1/1/1965 71.97 

6 1/1/1968 71.97 

7 1/1/1973 71.97 

8 1/1/1978 71.96 

9 1/1/1981 71.96

WELL 7-^79 NODE 10, 20

1 1/1/1921 113.28 

2 1/1/1946 113.28

3 1/1/1953 113.27

4 1/1/1958 113.27

5 1/1/1965 113.27

6 1/1/1968 113.22 

7 1/1/1973 113.18 

8 1/1/1978 113.15 

9 1/1/1981 113.14

WELL 11^3 NODE 12, 12

1 1/1/1921 74.18

2 1/1/1946 74.13

3 1/1/1953 74.06

4 1/1/1958 74.05

5 1/1/1965 74.05

6 1/1/1968 73.97 

7 1/1/1973 73.93 

8 1/1/1978 73.95 

9 1/1/1981 73.74

WELL 11-97 NODE 15, 9

1 1/1/1921 10.66 

2 1/1/1946 10.66

3 1/1/1953 10.66 

4 1/1/1958 10.65

5 1/1/1965 10.64

6 1/1/1968 10.64 

7 1/1/1973 10.64 

8 1/1/1978 10.64 

9 1/1/1981 10.63

-30.06

-33.28

-39.22

-39.18

_qq OS. 77I i

66.50 

66.35 

69.42 

66.61 

65.83

_

110.04

109.47 

110.52 

110.20 

110.06

78.96 

76.07 

76.04

_

1.87 

1.65 

0.92

7.97

-0.51

2.05

-5.82

q cJ.^V/ AR

5.47 

5.62 

2.55 

5.36 

6.13

_

3.23

3.76 

2.66 

2.95 

3.08

-5.03 

-2.12 

-2.30

_

I

8.77 

8.99 

9.70
TABLE 15 H145

TABLE 15. Comparison between simulated and measured water levels at the end of each pumping period Continued

Pumping , , , Simulated 

. *\ 6 End date , , , period water level

Measured Water-level 

water level difference

LOWER KIRKWOOD-COHANSEY AQUIFER AND

CONFINED KIRKWOOD AQUIFER (A8)- Continued

WELL 29-17 NODE 19, 36

1 1/1/1921 8.56

2 1/1/1946 7.91

3 1/1/1953 7.28

4 1/1/1958 6.90

5 1/1/1965 6.26

6 1/1/1968 5.78

7 1/1/1973 4.93

8 1/1/1978 4.24

9 1/1/1981 3.92

WELL 29-514 NODE 18, 33

1 1/1/1921 45.04

2 1/1/1946 45.02

3 1/1/1953 45.00

4 1/1/1958 44.99

5 1/1/1965 44.97

6 1/1/1968 44.96

7 1/1/1973 44.93

8 1/1/1978 44.84

9 1/1/1981 44.81

4.89

4.39

4.36

4.46

3.85

35.90

36.44

37.83

34.48

35.91

1.37

1.38

0.57

-0.22

0.07

9.07

8.52

7.10

10.37

8.89

UPPER KIRKWOOD-COHANSEY AQUIFER (A9)

WELL 5-570 NODE 16, 25

1 1/1/1921 44.12

2 1/1/1946 44.11

3 1/1/1953 44.11

4 1/1/1958 44.11

5 1/1/1965 44.11

6 1/1/1968 44.10

7 1/1/1973 44.10

8 1/1/1978 44.09

9 1/1/1981 44.09

WELL 5-628 NODE 16, 29

1 1/1/1921 75.71

2 1/1/1946 75.71

3 1/1/1953 75.71

4 1/1/1958 75.71

5 1/1/1965 75.71

6 1/1/1968 75.70

7 1/1/1973 75.70

8 1/1/1978 75.70

9 1/1/1981 75.70

WELL 5-689 NODE 14, 31

1 1/1/1921 123.52

2 1/1/1946 123.52

3 1/1/1953 123.51

4 1/1/1958 123.51

5 1/1/1965 123.50

6 1/1/1968 123.50

7 1/1/1973 123.49

8 1/1/1978 123.49

9 1/1/1981 123.48

_

_

48.17

49.72

49.82

56.30

48.37

49.05

_

77.06

77.23

76.56

76.55

76.97

77.85

77.60

75.74

_

_

127.70

129.15

130.10

135.32

131.75

128.44

_

_

-4.06

-5.61

-5.72

-12.20

-4.27

-4.96

_

-1.35

-1.52

-0.85

-0.85

-1.26

-2.15

-1.90

-0.05

_

-4.19

-5.64

-6.60

-11.83

-8.27

-4.96

Pumping E Simulated 

period water level

Measured 

water level

Water-level 

difference

UPPER KIRKWOOD-COHANSEY AQUIFER (A9)- Continued

WELL 7-503 NODE 9, 20

1 1/1/1921 137.97

2 1/1/1946 137.96

3 1/1/1953 137.94

4 1/1/1958 137.93

5 1/1/1965 137.91

6 1/1/1968 137.90

7 1/1/1973 137.87

8 1/1/1978 137.84

9 1/1/1981 137.82

WELL 9-23 NODE 19, 13

1 1/1/1921 24.76

2 1/1/1946 24.74

3 1/1/1953 24.74

4 1/1/1958 24.73

5 1/1/1965 24.72

6 1/1/1968 24.71

7 1/1/1973 24.71

8 1/1/1978 24.70

9 1/1/1981 24.69

WELL 9-48 NODE 23, 7

1 1/1/1921 -2.21

2 1/1/1946 -7.28

3 1/1/1953 -10.53

4 1/1/1958 -17.39

5 1/1/1965 -20.23

6 1/1/1968 -20.35

7 1/1/1973 -20.90

8 1/1/1978 -24.31

9 1/1/1981 -26.18

WELL 9-60 NODE 22, 8

1 1/1/1921 1.73

2 1/1/1946 -2.66

3 1/1/1953 -5.71

4 1/1/1958 -11.96

5 1/1/1965 -17.37

6 1/1/1968 -18.49

7 1/1/1973 -19.63

8 1/1/1978 -24.41

9 1/1/1981 -26.79

WELL 9-99 NODE 22, 11

1 1/1/1921 8.43

2 1/1/1946 6.81

3 1/1/1953 5.67

4 1/1/1958 3.41

5 1/1/1965 1.23

6 1/1/1968 0.72

7 1/1/1973 0.29

8 1/1/1978 -1.40

9 1/1/1981 -2.19

_

143.61

137.40

136.19

24.48

24.81

25.81

26.38

25.77

25.11

-10.98

-13.76

-17.11

-17.97

-21.37

-22.91

-3.67

-5.53

-8.71

-14.49

-15.35

5.06

4.70

5.58

6.11

4.84

4.04

-5.75

0.44

1.63

0.25

-0.09

-1.10

-1.68

-1.08

-0.42

-6,41

-6.47

-3.24

-2.93

-2.94

-3.27

-13.69

-12.96

-10.92

-9.92

-11.45

-1.65

-3.47

-4.86

-5.81

-6.24

-6.23
H146 REGIONAL AQUIFER SYSTEM ANALYSIS-NORTHERN ATLANTIC COASTAL PLAIN

TABLE 15. Comparison between simulated and measured water levels at the end of each pumping period Continued

Pumping ,-, , , , Simulated 

period Enddate water level

Measured 

water level

Water-level 

difference

UPPER KIRKWOOD-COHANSEY AQUIFER (A9)- Continued

WELL 11-141 NODE 16, 13

1 1/1/1921 22.07

2 1/1/1946 22.00

3 1/1/1953 22.00

4 1/1/1958 21.94

 5 1/1/1965 21.65

6 1/1/1968 21.20

7 1/1/1973 21.07

8 1/1/1978 21.01

9 1/1/1981 20.86

WELL 11-162 NODE 14, 13

1 1/1/1921 61.88

2 1/1/1946 61.79

3 1/1/1953 61.78

4 1/1/1958 61.79

5 1/1/1965 61.64

6 1/1/1968 61.46

7 1/1/1973 61.31

8 1/1/1978 61.24

9 1/1/1981 61.19

WELL 11-188 NODE 9, 12

1 1/1/1921 83.23

2 1/1/1946 83.22

3 1/1/1953 83.22

4 1/1/1958 83.21

5 1/1/1965 83.21

6 1/1/1968 83.03

7 1/1/1973 82.96

8 1/1/1978 82.93

9 1/1/1981 83.00

WELL 29-20 NODE 19, 36

1 1/1/1921 6.34

2 1/1/1946 5.97

3 1/1/1953 5.68

4 1/1/1958 5.52

5 1/1/1965 5.25

6 1/1/1968 5.03

7 1/1/1973 4.67

8 1/1/1978 4.40

9 1/1/1981 4.28

WELL 29-486 NODE 13, 34

1 1/1/1921 114.42

2 1/1/1946 114.42

3 1/1/1953 114.41

4 1/1/1958 114.41

5 1/1/1965 114.40

6 1/1/1968 114.39

7 1/1/1973 114.22

8 1/1/1978 113.64

9 1/1/1981 113.39

_

12.78

13.00

15.31

13.25

12.62

_

_

62.11

57.68

58.36

_

_

71.20

70.80

70.52

_

4.29

4.40

4.77

4.57

4.12

126.65

123.65

123.85

124.55

128.60

123.95

123.93

8.87

8.20

5.76

7.76

8.23

_

_

-0.80

3.56

2.83

11.76

12.14

12.48

0.96

0.63

-0.10

-0.17

0.16

-12.23

-9.24

-9.45

-10.16

-14.37

-10.31

-10.54

PumP,inS Enddate Simulated 

period water level

Measured 

water level

Water-level 

difference

HOLLY BEACH AQUIFER (AID)

WELL 9-20 NODE 23, 6

1 1/1/1921 1.44

2 1/1/1946 1.44

3 1/1/1953 1.44

4 1/1/1958 1.44

5 1/1/1965 1.44

6 1/1/1968 1.44

7 1/1/1973 1.44

8 1/1/1978 1.44

9 1/1/1981 1.44

WELL 9-26 NODE 23, 7

1 1/1/1921 5.03

2 1/1/1946 5.03

3 1/1/1953 5.03

4 1/1/1958 5.03

5 1/1/1965 5.03

6 1/1/1968 5.03

7 1/1/1973 5.03

8 1/1/1978 5.03

9 1/1/1981 5.02

WELL 9-61 NODE 22, 8

1 1/1/1921 7.83

2 1/1/1946 7.83

3 1/1/1953 7.83

4 1/1/1958 7.83

5 1/1/1965 7.83

6 1/1/1968 7.83

7 1/1/1973 7.82

8 1/1/1978 7.81

9 1/1/1981 7.80

WELL 9-81 NODE 23, 10

1 1/1/1921 10.43

2 1/1/1946 10.43

3 1/1/1953 10.43

4 1/1/1958 10.42

5 1/1/1965 10.42

6 1/1/1968 10.42

7 1/1/1973 10.42

8 1/1/1978 10.42

9 1/1/1981 10.42

WELL 9-98 NODE 22, 11

1 1/1/1921 13.18

2 1/1/1946 13.15

3 1/1/1953 13.12

4 1/1/1958 13.10

5 1/1/1965 13.07

6 1/1/1968 13.06

7 1/1/1973 13.17

8 1/1/1978 13.16

9 1/1/1981 13.16

3.66

4.04

5.19

4.93

3.95

1.80

1.61

1.79

2.24

1.67

1.50

7.57

8.38

8.42

7.50

7.30

6.95

5.48

7.55

7.96

7.50

5.46

_

17.14

16.02

14.37

-2.22

-2.60

-3.75

-3.49

-2.51

3.23

3.42

3.23

2.78

3.35

3.53

0.26

-0.55

-0.61

0.31

0.51

3.47

4.94

2.87

2.46

2.92

4.96

_

-3.98

-2.86

-1.21
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