PLAN OF STUDY FOR THE 

NORTHERN ATLANTIC COASTAL PLAIN 

REGIONAL AQUIFER SYSTEM ANALYSIS 

U. S. Geological Survey 

Water Resources Investigations 80-16 

, . .., 

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50272 -J 01 ·,, 

REPORT DOCUMENTATION l_l:_REPORT NO. 3. Recipient's Accession No. 

PAGE 

4. Title and Subtitle 5. Report Date 

Plan of Study for the Northern Atlantic Coastal Plain April 1980 

Regional Aquifer System Analysis 6. 

7. Author(s) 8. Performing Organization Rept. No. 

Harold Meisler USGS/WRI 80-16 

9. Performing Organization Name and Address 10. Project/Task/Work Unit No. 

U.S. Geological Survey, Water Resources Division 

1 436 Federal Building 11. Contract(C) or Grant(G) No. 

402 E. State Street 

(C) Trenton, NJ 08607 

(G) 

12. Sponsoring Organization Name and Address 13. Type of Report & Period Covered 

U.S. Geological Survey, Water Resources Division 

Northeastern Region, Mail Stop Planning 433 

12201 Sunrise Valley Drive, Reston, VA 22092 14. 

15. Supplementary Notes 

200 Hi. Abstract (Limit: words) Sediments of Cretaceous to Holocene age compose the Northern Atlantic 

Coastal Plain aquifer system in an area of 50,000 square miles from North Carolina to 

New York. The aquifer system is the principal source of water supply for most of the 

area. About 1.4 billion gallons are withdrawn each day. Increasing pumpage has create~ 

problems such as declining water levels, saltwater intrusion, and land subsidence. 

The U.S. Geological Survey has begun a comprehensive study of the aquifer system that 

will define the geology, hydrology, and geochemistry of the system. The effects of 

future utilization of the aquifer system will be determined and alternative water 

withdrawal plans will be evaluated through computer simulation modeling. This report 

describes the objectives, organization, and work plans of the study. 

17. Document Analysis a. Descriptors 

<'•Aquifers, ,•,Atlantic Coastal Plain, '"Computer models, Delaware, Geochemistry, 

*Groundwater, Maryland, New Jersey, New York, North Carolina, Pumping, *Regional analysis 

Saline water-freshwater interface, *Project planning, Water chemistry, Water management, 

Virginia. 

b. Identifiers/Open-Ended Terms 

Cones of depression, Delmarva peninsula, Ground-water management, Hydrogeologic maps, 

Long Island, Regional aquifer system. 

c. COSATI Field/Group 

18. Availability Statement 19. Security Class (This Report) 21. No. of Pages 

No restriction on distribution UNCLASSIFIED 27 

20. Security Class (This Page) 22. Price 

UNCLASSIFIED 

(See ANSI-Z39.18) See Instructions on Reverse OPTIONAL FORM 272 (4-77) 

(Formerly NTIS-35) 

Department of Commerce 
PLAN OF STUDY FOR THE NORTHERN ATLANTIC COASTAL PLAIN 

REGIONAL AQUIFER SYSTEM ANALYSIS 

By Harold Meisler 

U.S. GEOLOGICAL SURVEY 

Water Resources Investigations 80-16 

April 1980 
UNITED STATES DEPARTMENT OF THE INTERIOR 

Cecil D. Andrus, Secretary 

GEOLOGICAL SURVEY 

H. w. Menard, Director 

For additional information write to: 

U.S. Geological Survey 

436 Federal Building P.O. Box 1238 

Trenton, New Jersey 08607 
CONTENTS 

PAGE 

Abstract----------------------------------------------- 1 

Introduction------------------------------------------- 2 

Hydrogeologic setting-------------------------------- 2 

Problem--------------------~------------------------- 9 

Objectives------------------------------------------- 10 

Approach--------------------------------------------- 10 

Organization of the study---------------------------- 11 

Relation to other studies---------------------------- 12 

Plan of study----~----------------------------~-------- 13 

District work plans------------------------------------ 18 

Maryland, Delaware, and the District of Columbia----- 18 

New Jersey------------------------------------------- 21 

New York--------------------------------------------- 23 

North Carolina--------------------------------------- 24 

Virginia--------------------------------------------- 25 

Selected references------------------------------------ 27 

ILLUSTRATIONS 

Figure 1. Map showing the location of northern 

Atlantic Coastal Plain--------------------- 3 

2. Configuration of the bedrock surface beneath 

the Coastal Plain sediments---------------- 4 

3. Structure contour map of the top of the 

Cretaceous sediments----------------------- 6 

4. Stratigraphic correlation chart of the 

northern Atlantic Coastal Plain------------ 7 

5. Schedule of work elements-------------------- 17 

6. Preliminary designation of aquifers for 

district work plans------------------------ 19 

TABLES 

Table 1. Estimated ground-water withdrawal in 1978---- 8 

iii 
PLAN OF STUDY FOR THE NORTHERN ATLANTIC COASTAL 

PLAIN REGIONAL AQUIFER SYSTEM ANALYSIS 

Harold Meisler 

ABSTRACT 

Sediments of Cretaceous to Holocene age 

compose the Northern Atlantic Coastal Plain aquifer 

system in an area of 50,000 square miles in parts 

of New York, New Jersey, Delaware, Maryland, 

Virginia, and North Carolina. The aquifer system 

is a major source of water supply in the area. 

About 1 . 4 billion gallons is withdrawn from its 

aquifers each day. Increasing withdrawal of ground 

water has created or intensified several problems 

such as declining water levels, development of 

large cones of depression, saltwater intrusion, 

spreading of ground-water contamination, and land 

subsidence. 

The U.S. Geological Survey has begun a 

comprehensive study that will define the geology, 

hydrology, and geochemistry of the aquifer system. 

The effects of future utilization of the aquifer 

system will be determined and alternative plans for 

water withdrawal will be evaluated through computer 

simulation modeling. This report describes the 

objectives, organization, and work plans of the 

study, and describes the work to be accomplished in 

each U.S. Geological Survey 

District of the study area. 
INTRODUCTION 

The Northern Atlantic Coastal Plain is an area of about 

50,000 square miles extending northeastward from North 

Carolina to Long Island, New York (figure l). It is 

underlain by an eastward thickening wedge of predominantly 

unconsolidated sediments. This sedimentary wedge forms a 

complex aquifer system that provides most of the area's water 

supply. withdrawal of water from the system is estimated to 

have been 1. 4 billion gallons per day in 1 978. Problems 

associated with increasing withdrawal will adversely affect 

the long-term utilization of the aquifer system. 

Hydrogeologic Setting 

Northern Atlantic Coastal Plain sediments cQnsist mostly 

of sand, silt, clay, shale, and limestone with minor amounts 

of gravel. Most of the limestone occurs in North Carolina, 

although minor amounts are present as far north as New 

Jersey. The Coastal Plain sediments range in age from Early 

Cretaceous (probably Jurassic age locally) to Holocene and 

overlie crystalline bedrock of Paleozoic and Precambrian (?) 

age and sedimentary and igneous rocks of Triassic age. 

Generally, the sediments dip gently to the east or southeast 

at 10 to 50 feet per mile, thickening from a featheredge at 

the western limit of the Coastal Plain to about 8,000 feet at 

the eastern edge of the Delmarva Peninsula and 10,000 feet at 

Cape Hatteras, North Carolina. Figure 2 shows the 

configuration of the top of the bedrock beneath the Coastal 

Plain sediments. 

2 
7 

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-·-·-·-·-·-·-·-·-1') -----·-·'-, 

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...... '·-·-·-·-·-· New .fork· ., ., ~ 

; Trent<)n 

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( 

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_i... c-· -·- \..- - - '\j 

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30° I 

l 

I 

,;> •• 

.. ... 25° 0 100 200 300 400 500 MILES 

0 200 400 600 800 KILOMETERS 

9 5° 9 0° 8 5° 8 0° 

Figure 1.-.Location of the Northern Atlantic Coastal Plain.· 

3 
410 

EXPlANA T!O N 

Map showing altitude of bedrock. 

Datum in feet. 

40° Dati fro111 Br•wn and etlttn 1972. 40' 

39° 

39° 

~ 

"t 

/J ' i<t 

380 j (J 

38'' 

/ 0 

...._,, f (J 

37° ' 37° A. 

~ 

"t 

lt..._ 

N " 

" 36\l 

~' ~- "t 

A R 

35° 

SCALE 

KILOMETERS 

34'' 

figure 2.-- Configuration of the bedrock surfaces beneath the Coastal Plain sediments. 
Sediments of Cretaceous age thicken eastward from a 

featheredge along their western boundary to about 5,000 feet 

at the southern tip of New Jersey and the eastern edge of the 

Delmarva peninsula and to 5,900 feet as reported by Perry and 

others ( 1975, p. 1534) at Cape Hatteras, North Carolina. 

Cretaceous sediments constitute about three q_uarters of the 

total sedimentary wedge and Lower Cretaceous sediments make 

up about half of the wedge. The configuration of the top of 

the Cretaceous sediments is shown in figure 3. Lower 

Cretaceous sediments are largely of nonmarine origin except 

in North Carolina where sediments of marine origin 

predominate. Upper Cretaceous deposits contain marine, 

marginal marine, and nonmarine sediments. Nonmarine 

sediments are most abundant in the lower units of the Upper 

Cretaceous except in North Carolina and New Jersey where 

marine and marginal marine sediments are prominent. Marine 

and marginal marine sediments predominate in the upper units 

of the Upper Cretaceous. 

The overlying sediments of Cenozoic age thicken eastward 

to about 2,000 feet at the southern tip of New Jersey and the 

eastern edge of the Delmarva Peninsula and to about 2, 800 

feet at Cape Hatteras, North Carolina. Cenozoic sediments 

constitute about one q_uarter of the Coastal Plain sedimentary 

wedge. Sediments of Paleocene through Miocene age are 

chi e f 1 y of mar in e a'n d marginal mar in e or i g i n , w he r e as 

sediments of Pliocene through Holocene age are largely 

nonmarine but contain some marginal marine deposits. 

Correlation of stratigraphic units in the various states of 

the Northern Atlantic Coastal Plain is shown in the· 

Correlation Chart (figure 4). Also shown on the chart is the 

stratigraphic seq_uence of seventeen chronostratigraphic 

units (strata of the same age that have the same or different 

lithologies) developed by Brown, Miller, and Swain (1972) for 

the entire Northern Atlantic Coastal Plain. The 

chronostratigraphic units are correlated by system and series 

with the other stratigraphic seq_uences but correlation of 

individual chronostratigraphic units with individual 

formations is not implied in the Correlation Chart. 

Many of the more permeable stratigraphic units have been 

identified as aq_uifers. These are listed for each of the 

Northern Coastal Plain states in the section entitled 

"District ~vork Plans" and their stratigraphic relation shown 

in figure 6. The aq_uifers are separated by confining beds of 

widely differing permeability, ranging from very leaky 

confining layers, such as the silts of Miocene age on the 

Delmarva Peninsula, to almost impermeable layers, such as 

clays of Cretaceous age in Maryland and New Jersey. In 

general, however, the aq_uifers are not independent units and 

each is part of a complex hydrologic system. Sand aq_uifers 

of Cretaceous age supply about two-thirds of the present-day 

water supply as indicated.by table l which shows estimates of 

ground-water withdrawal by locality and geologic age. 

5 
1" 

EXPLANATION 

Shows altitude of top of Cretaceous. 

Contour intervals- 1000 feet. 

40° Data from Brown and others 1972 40° 

35° 

SCALE 

75 100 MILES 

tbo t25 1~0 KILOMETERS 

34° 

Figure 3.-- Structure contour mop of the Cretaceous sediments. 

6 
Figure 4.--Generalized stratigraphic correlation chart of the Northern Atlantic Coastal Plain 

BROWN, MILLER 

SYSTEM SERIES AND SWAIN, 19 72 NORTH CAROLINA VIRGINIA MARYLAND DELAWARE NEW JERSEY NEW YORK 

Rocks of post Cape May Formation Upper Pleistocene . 

Unnamed Undifferentiated deposits Undifferentiated deposits Undifferentiated deposits depos~ts 

Quaternary Pleistocene Niocene age Undifferentiated deposits jGardners Clay 

Jameco Gravel 

Pliocene Yorktown Formation Yorktown Formation Yorktown Formation Undifferentiated deposits <lJ <lJ 

~ 

Rocks of Late . . m ~ Brandywine 

p. Miocene age Pungo R~ver <lJ <lJ Formation Format~on p. ;:J p. p. Chesapeake Group m o m ::J Cll H St. Marys Formation (/) 0 St. Miocene undivided RocksofMiddle Belgrade Formation <lJ 

.c (j Choptank Formation .c 

Ill H 

(j 

Miocene age u u Calvert Formation 

Rocks of Tertiary Oligocene River Bend Formation Unnamed 01 igocene age 

Rocks of Chicka\',ominy Formation 

Eocene Castle HayneFormation 

Nanjemoy Formation Nanjemoy Formation Nanjemoy Formation 

Unnamed ctuL "' Marlboro Clay ----t------------1'"'-.--------

Rocks of Aquia Formation Aquia Formation p. Vincentown Formation Paleocene Beaufort Formation Midway age Hornerstown Sand Brightseat Formation Brightseat Formation 

--.1 

Rocks of Tinton Sand 

Unit A Severn Formation Red Bank Sand Monmouth Group 

Rocks of Mount Laurel Sand Peedee Formation Unit B Mattaponi Formation Wenonah Formation Matawan Formation Upper Rocks of Marshalltown Formation Englishtown Formation Matawan Group Unit C Black m Cretaceous Creek Englishtown Formation £ ;:JIMarshallta;,n Formation 

;;t CJ Woodbury Clay 

Cretaceous Rocks Formation of Merchantville Formation ~ Merchantville Formation 

Unit D Cape Fear Magothy Formation Magothy Formation Magothy Formation Magothy Formation Formation Rocks of Raritan Unit E Raritan Formation Formation 

Rocks of 

Unit F Patapsco Formation 

Patapsco Potomac Group Potomac Group Formation Lower Rocks of Unnamed §' Cretaceous Arundel Formation Unit G 0 

Rocks of 

Unit H Jurassic (?)!Upper Rocks of Unnamed JurassicC?) Unit I 

NOTE: Chronostratigraphic units of Brown, Miller, and Swain, 1972, are not correlated here with other formations or groups. Not all formations appearing on the same 

horizontal 1 ine are necessarily exact time equivalents. The diagonal lines indicate that the section is not present. 
LOCALITY 

Long Island, N.Y. 

New Jersey 

Maryland, Delaware 

and 

District of Columbia 

Virginia 

North Carolina 

Total, by age 

Table 1.--Estimated ground-water withdrawals 

(million gallons per day) 

1978 

ES~IMATED WITHDRAWALS FROM AQUIFERS, 

Cretaceous 

375 

265 

90 

140 

60 

----

BY AGE 

Tertiary 

120 

50 

5 

95 

Quaternary 

125 

1 5 

60 

TOTAL 

500 

400 

200 

145 

155 

----

930 270 200 1 '400 

CD 
Problem 

The long-term uti'lity of the Northern Atlantic Coastal 

Plain aquifer system is threatened by increasing demand for 

water supply. This aquifer system is a major source of water 

supply for urban and suburban centers and industries, as well 

as for irrigation and domestic use. Intensive ground-water 

withdrawal has resulted in declining water levels and 

development of large cones of depression in several aquifers 

while other aquifers having significant development potential 

remain relatively unused. Major cones of depression 

resulting from large ground-water withdrawals for industrial 

and public supply occur in New Jersey, the Delmarva 

Peninsula, and southeastern Virignia. Ground-water pumpage 

associated with phosphate mining in northeastern North 

Carolina has created a cone of depression extending over an 

area of more than 2,000 square miles. Water levels have 

declined more than 125 feet at the center of the North 

Carolina cone. Water levels have declined 200 feet at the 

center of the cone at Franklin, Virginia. This cone extends 

over an area of more than 5,000 square miles in Virginia and 

North Carolina. Coalescing cones of depression underlie 

virtually the entire 4,000 square mile Coastal Plain of New 

Jersey and 3,000 square miles of northern Delmarva Peninsula. 

Water-level declines are typically 100 to 200 feet at the 

center of the cones in New Jersey and on the Delmarva 

Peninsula. 

Declining water levels, in turn, are causing saltwater 

intrusion and movement of contaminants towards pumping 

centers. Saltwater intrusion is possible from two sources: 

saline water in the ocean, bays, and estuaries overlying or 

adjacent to the shallow parts of the aquifers; and saline 

ground water in the deeper parts of the aquifers. The 

potential for saltwater intrusion appears greatest in Long 

Island, southeastern Virginia, northeastern North Carolina, 

and New Jersey. The complexity of saltwater-freshwater 

relations in the Coastal Plain aquifers is underscored by the 

occurrence "of relatively fresh water (salinities less than 3 

parts per thousand) extending as much as 60 nautical miles 

seaward from the New Jersey coast." (Hathaway and others, 

1 97 6' p. 4) . 

Release of water from storage in confining layers has 

caused an unknown amount of consolidation of some of these 

layers resulting in subsidence of the land surface. 

Indications of land subsidence are greatest in New Jersey and 

in southeastern Virginia where subsidence is estimated to be 

as high as 0.2 inch per year. 

9 
Quantitative evaluation of this large, complex, and 

inadequately understood aquifer system and the tools to 

predict the consequences of its continued use are needed in 

order to develop the system safely and efficiently. A 

regional study, encompassing the entire Northern Atlantic 

Coastal Plain is needed for a comprehensive understanding of 

the aquifer system and its response to multistate 

development. 

Objectives 

The objectives of the Northern Atlantic Coastal Plain 

Regional aquifer system analysis are: 

1. Define the regional aquifer system. Describe its geology, 

hydrology, and geochemistry. Define the predevelopment flow 

system and the changes caused by development. 

2. Simulate both the predevelopment and present flow 

conditions in the aquifer system by digital computer models. 

3. Use simulation models to determine the effects of 

continued and future stress on the regional aquifer system and 

on streamflow. Evaluate alternative ground-water withdrawal 

plans by estimating their hydrologic effects. 

4. Determine the location of the saltwater-freshwater 

interface and evaluate its movement. 

5. Formulate a regional data-collect ion program to monitor 

future water use, water levels, and water-quality changes and 

to provide information needed for more detailed predictive 

models. 

Approach 

The objectives of the study will be met through the 

following steps: ( 1) compiling and analyzin~ available 

geologic, hydrologic, and water quality data; (2) developing 

regional hydrogeologic and geochemical maps; ( 3) collecting 

and analyzing additional data in order to improve and refine 

regional maps; (4) developing and calibrating regional steady 

state and transient computer simulation models; (5) studying 

the relationship of saltwater to freshwater and ( 6) using 

simulation models to evaluate the effects of ground-water 

withdrawals on ground-water movement, water levels, and base 

flow of streams. 

10 
Regional computer models will simulate from eight to ten 

aquifers. Aquifers and confining beds will be subdivided 

into an appropriate number of model layers to be determined 

during the study. From 2,000 to 4,000 nodes will be utilized 

for each model layer, an average size node covering 40 to 60 

square miles. They· will cover the entire Northern Atlantic 

Coastal Plain and part of the adjacent continental shelf. 

Subregional computer models will be developed within U.S. 

Geological Survey Districts. Each subregional model will 

cover approximately the coastal plain area of one or, in the 

case of Maryland and Delaware, two states. The Virginia 

District model will extend southward to Albemarle Sound in 

North Carol ina and the North Carolina District model will 

extend southward from Albemarle Sound to South Carolina. 

Subregional models will simulate up to ten layers and have on 

the order of 2,000 to 4,000 nodes per layer. Variable grids 

containing fine grid spacing will be utilized in areas of 

heaviest pumping or other significant problems. 

Organization of the Study 

The Northern Atlantic Coastal Plain regional aquifer 

system analysis will be done during October 1, 1979 to 

Sept ember 30, 1 984. A regional project staff of the U.S. 

Geological Survey will be located in Trenton, New Jersey. 

Subregional projects will be conducted concurrently· for four 

years, October 1 , 1979 to September 30, 1983, in five U.S. 

Geological Survey Districts: New York (Syosset, N.Y.), New 

Jersey (Trenton, N.J.), Maryland, Delaware and the District 

of Columbia (Towson, Md.), Virginia (Richmond, Va.), and 

North Carolina (Raleigh, N.C.). Subregional projects will be 

funded as part of the regional aquifer system analysis. 

The regional project staff will design and conduct the 

regional study in coordination with each participating 

U.S. Geological Survey District and will provide technical 

direction for the planning and execution of the subregional 

projects. The regional staff will coordinate regional and 

subregional projects, develop regional steady state and 

transient computer simulation models, and supply boundary 

conditions for the subregional computer simulation models. 

Subregional projects will be the responsibility of the 

respective Districts. District staffs will develop 

subregional steady state and transient computer simulation 

models as described in this report in the section entitled 

"District Work Plans." The District staffs will collect and 

analyze th·e data required for subregional and regional 

models. The subregional projects will also furnish much of 

this information to the regional project staff in the form of 

hydrogeologic and geochemical maps. 

11 
Relation to Other Studies 

Most of the knowledge of the ground-water resources and 

hydrogeology of the Northern Atlantic Coastal Plain has 

resulted from the long-term cooperative program of the U.S. 

Geological Survey with state and other governmental agencies. 

Principal cooperating agencies have been the Delaware 

Geological Survey, Maryland Geological Survey, New Jersey 

Department of Environmental Protection (formerly Department 

of Conservation and Economic Development), North Carolina 

Department of Natural Resources and Community Development 

(formerly Department of Water and Air Resources), Virginia 

State Water Control Board, Nassau County (New York) 

Department of Public Works, Suffolk County (New York) Water 

Authority, and Suffolk County Department of Health Services. 

The Northern Coastal Plain regional aquifer study will 

be coordinated with related cooperative projects in the 

participating Districts. These include, in addition to 

ongoing programs to collect hydrologic data in each District: 

(a) Countywide ground-water studies in Nassau and 

Suffolk Counties, New York, James City and Fairfax 

Counties, Virginia; 

(b) Computer simulation models in Nassau and Suffolk 

Counties, New York, several models of the Potomac Group 

in Delaware and Maryland, a model of the Piney Point and 

Cheswold aquifers in Delaware, a model of the Aquia, 

Piney Point, and Nanjemoy aquifers in southern Maryland, 

and a model of the Cohansey Sand in New Jersey; 

(c) Other projects such as subsidence studies in New 

Jersey and southeastern Virginia, hydrogeology of the 

water-table aquifer in the Delmarva peninsula, hydrology 

of the Dismal Swamp, Virginia, hydrology and water 

quality of the Potomac-Raritan-Magothy aquifer system in 

the Delaware Valley, New Jersey, saltwater-freshwater 

relations in Virginia, and the feasibility of recharging 

tertiary treated sewage in Nassau County, New York. 

Unpublished data collected for the regional aquifer 

stu,dy as well as simulation models and their documentation 

will be released and available to cooperating agencies and 

the public. 

12 
PLAN OF STUDY 

Work elements of the study are shown in the following 

outline. 

A. Planning and staffing. 

1. Develop regional and subregional project proposals 

and descriptions. 

2. Develop detailed work plans for regional and 

subregional projects. 

3. Assemble staffs in regional and district offices. 

The regional staff will consist of four hydrologists 

with the following principal areas of responsibility; 

(a) overall direction of project, (b) hydrology and 

geology, (c) computer simulation, and (d) geochemistry. 

4. Organize regional liaison committee. 

B. Hydrogeology. 

1. Compile and review available data on the 

hydrogeologic framework. 

a. Correlate stratigraphic data. 

b. Identify the aquifers and confining layers; their 

distribution, structure, and thickness. 

c. Evaluate the following hydraulic properties of 

aquifers and confining layers: hydraulic conductivity, 

storage coefficient, specific storage, specific yield. 

2. Evaluate and interpret data. 

Interpret hydrogeologic maps and other information 

needed for regional and subregional computer simulation 

modeling. 

3. Data collection program. 

a. Conduct test drilling, pumping tests, and 

geophysical logging. 

b. Update stratigraphic and structural data. 

c. Update information on the hydraulic properties of 

aquifers and confining layers. 

d. Collect subsidence data in Virginia and New 

Jersey. 

13 
4. Revise hydrogeologic maps and information needed for 

improved regional and subregional computer simulation 

modeling. 

5. Complete interpretation of hydraulic properties based 

on computer simulation modeling. 

c. Hydrology. 

1. Compile and review available hydrologic data. 

a. Water-level histories, potentiometric heads. 

b. Predevelopment recharge and discharge. 

c. Pumpage from wells. 

d. Ground water-surface water relations. 

2. Evaluate and interpret data. 

Interpret hydrologic maps, hydrographs, and other 

information needed for regional and subregional computer 

simulation modeling. 

3. Data collection program. 

a. Update and improve pumpage and potentiometric head 

data. 

b. Update and improve base-flow data. 

4. Revise hydrologic maps and information needed for 

improved regional and subregional computer simulation 

modeling. 

5. Prepare final interpretation of flow system based on 

computer simulation modeling. 

D. Geochemistry and water ~uality~ 

1. Assemble and evaluate available data. 

a. Develop preliminary maps showing concentrations of 

significant constituents. 

b. Determine significant historical changes in water 

~uality. 

2. Develop program of water-~uality sampling and 

analysis. 

3. Revise preliminary .maps and develop new water-quality 

14 
maps. 

4. Relate distribution of water-quality parameters to 

the three-dimensional flow system. Relate water quality 

to recharge areas, movement within aquifers and 

confining layers. 

5 . Study t he o c cur r e n c e o f s a l twa t e r , de f'i n e 

saltwater-freshwater relations, and evaluate saltwater 

movement as a result of ground-water withdrawal and past 

changes in sea level. 

6. Develop appropriate ground-water quality models. 

E. Computer simulation models of the aquifer system. 

1. Develop steady-state multilayer regional model. 

a. Develop a digital computer modeling program. 

b. Determine model boundaries, the aquifers to be 

simulated, the number of model layers to be used, and 

the finite difference grid. 

c. Calibrate model with predevelopment water levels. 

d. Provide boundary conditions to subregional models 

and help guide development of subregional steady-state 

models. 

e. Apply sensi ti vi ty analysis to determine the most 

important hydrologic properties and to determine new 

data needs. 

f. Revise and improve the model using new data. 

2. Develop transient multilayer regional model. 

Development of the transient model will be based upon 

results of the steady-state model. Cali brat ion of the 

transient model will be based on historical water 

levels, and pumpage data. 

3. Develop other simulation models. 

a. Cross-sectional models. 

b. Saltwater-freshwater models. 

c. Ground-water quality models. 

15 
F. Utilization of simulation models. 

1. Develop several scenarios of projected ground-water 

withdrawal. 

2. Test scenarios using simulation models to determine 

hydrologic effects. 

G. Reports. 

1. Plan of study (WRI). 

2. Regional hydrogeology ("WRI 1 professional paper 

chapter). 

3. Regional geochemistry ("WRI, professional paper 

chapter). 

4. Computer simulation models (professional paper 

chapters). 

5. Model documentation (open file). 

6. Saltwater-freshwater relationships (journal article, 

professional paper chapter). 

7. Other special studies (journal articles). 

H. Future studies and data collection. 

1. Identify data collection programs needed to improve 

understanding of the a~uifer system and update computer 

simulation models and their predictive capabilities. 

2. Identify areas for more detailed computer simulation 

models. 

Scheduling of these work elements is given in figure 5. 

16 
Planning 

. (A) 

Compile, Interpret data - Hydrogeology (B-1,2) 

I I 

Data Collection - Hydrogeology (B-3) -

1

InterpreJation - Hydrogeology CB-4,5) 

Compile, Interpret Data - Hyrlrology (C-1 ,~) 

I I 

Data Collecti9n - Hydrology (C-3) 

InterpreJation - Hydrology (C-4,5) 

Assemble, Evaluate Data - Geochemistry (~-1) 

Wat~r Quality Sampling aJd Analysis (D-2) 

lnJerpretation- Geochemistry (D-3,4,5,6) 

Steady State Models (E-1) 

Transient Models (E-2) 

Other Simulation Models (E-3) l I 

Model Utilization (F) 

Reports (G) 

Future Studies (H) 

1980 FY 1981 FY 1982 FY 1983 FY 1984 FY 

Figure 5.--Schedule of work elements. Letters in parentheses refer to outline headings in the text. 

/ 

f-J 

-:) 
DISTRICT WORK PLANS 

Maryland, Delaware, and The District of Columbia 

The Coastal Plain aquifer system underlies about 8, 000 

square miles in Maryland, Delaware, and the District of 

Columbia. The Coastal Plain sediments dip southeasterly and 

thicken to about 8,000 feet in the vicinity of Ocean City, 

Maryland. Eight principal and several minor aquifers have 

been identified in the area. From youngest to oldest, the 

principal aquifers (see figure 6) are: the Unconfined aquifer 

which includes beds of Pleistocene and Pliocene age; the 

upper Chesapeake aquifer of Miocene and Pliocene age; lower 

Chesapeake aquifer of Miocene age; the Piney Point aquifer of 

Eocene age; Aquia and Rancocas aquifers of Paleocene age; the 

Magothy aquifer of Late Cretaceous age; and the Patapsco and 

Patuxent (Potomac Group) aquifers of Early and Late 

Cretaceous age. 

Withdrawal from these units is estimated at 200 Mgal/d. 

A total of about 90 Mgal/ d was withdrawn from the three 

aquifers of Cretaceous age, 50 Mgal/d from the four aquifers 

of Tertiary age, and 60 Mgal/ d is withdrawn from the 

unconfined aquifer. 

Large cones of depression have developed in more than a 

dozen areas in Maryland and Delaware as a result of 

ground-water withdrawal. Some of the more significant of 

these are in (1) the Potomac Group in the Baltimore 

industrial area, (2) the Aquia and Piney Point aquifers in 

the Calvert Cliffs-Lexington Park area in southern Maryland, 

(3) the Magothy and Piney Point aquifers in the vicinity of 

Cambridge on the eastern shore of Maryland, and (4) the Piney 

Point aquifer in the vicinity of Dover, Delaware. 

Problems or potential problems requiring investigation 

include intrusion of saline water from Chesapeake and 

Delaware Bays as well as from the ocean and land subsidence 

from dewatering and consequent compaction of confining beds. 

18 
MARYLAND, DELAWARE 

SERIES NORTH CAROLINA 

I I I 

Pleistocene 

-

I 

VIRGINIA DISTRICT OF COLUMBIA' ·NEW JERSEY NEW YORK 

f [£Pper~aacial 

~:i~i:- J I I Qua Unconfined ternary Unconfined 

Pliocene Upper 

Yorktown I I Chesapeake I I Upper 

Chesapeake I I Cohansey 

Miocene ~·~----

Kirkwood 

Oligocene 

Castle Hayne 

Eocene Nanjemoy Piney Point 

Manasquan 

Paleocene Beaufort Aquia Aquia and and 

Rancocas Rancocas 

Wenonah- Monmouth 

Pee dee Mount Laurel 

Matawan Englishtown Upper Magothy 

Upper 

- Late .... ._ ._ ._. 

Cretaceous -- I 

--- Cretaceous Magothy 

BLack Creek Magothy Middle Magothy 

Lower Magothy 

Raritan 

Tuscaloosa Lloyd 

Patapsco Undifferel§t:~a Lower Cretaceous Potomac 

Cretaceous 'u;diTt;;e"R~Ia Patuxent 

Cretaceous 

Figure 6.--Preliminary designation of aquifers for district work plans. 

f-J 

\D 
Available hydrologic and geologic data will be entered 

into a central system and stored on discs compatible with the 

Maryland and Delaware District's computer system. Additional 

data needs will be met through data-collection programs that 

include an observation-well network, a base-flow program to 

determine ground-water recharge and discharge, test drilling, 

, and geophysical logging. Water-quality data wi 11 be 

evaluated and additional samples collected; emphasis will be 

placed on evaluation of saline ground water. 

Three types of computer simulation modeling will be 

undertaken. A coarse-grid model of the Coastal Plain in 

Maryland and Delaware will simulate the eight principal and 

two minor aquifers by ten model layers and employ about 2,000 

nodes per model layer. This model will provide boundary 

conditions for fine-grid models in problem areas. Two 

proposed cross-sectional models to simulate steady-state 

conditions prior to ground water development will be made; 

(1) a section from Anne Arundel County to Ocean City, 

Maryland, and ( 2) a sect ion from Harford County, Maryland, 

eastward across Delaware to the ocean. 

Several reports will be prepared during the project. 

They include an open-file report, several U.S. Geological 

Survey Water Resources Investigation (WRI) map reports 

containing a series of hydrogeologic maps for each of the 

principal aquifers, a U.S. Geological Survey Professional 

Paper chapter on the results of the Maryland and Delaware 

subregional project, and journal articles on simulation 

modeling. 

20 
New Jersey 

The Coastal Plain aquifer system underlies about 4,000 

square miles in New Jersey. Coastal Plain sediments composed 

of clay, silt, sand, and gravel, range in age from Cretaceous 

to Holocene , and overlie bedrock of Pre cam b r ian , early 

Paleozoic and Triassic age. Thickness of the Coastal Plain 

s e d i men t s r an g e s f r om a f e at he r e d g e a 1 on g t he we s t. e r n 

boundary of the Coastal Plain to about 6, 500 feet at the 

southern tip of New Jersey. Principal aquifers (see figure 

6) of the New Jersey Coastal Plain, from youngest to oldest, 

are: the Cohansey Sand of Miocene age, the Kirkwood Formation 

of Miocene age, the Wenonah-Mount Laurel aquifer of Late 

Cretaceous age, the Englishtown aquifer of Late Cretaceous 

age, and the Potomac-Raritan-Magothy aquifer system of Early 

to Late Cretaceous age. 

Withdrawal from the principal aquifers and several minor 

aquifers in the New Jersey Coastal Plain is about 400 Mgal/d. 

About 250 Mgal/d is withdrawn from the Potoma~-RaritanMagothy aquifer system, 120 Mgal/ d from the Cohansey and 

Kirkwood aquifers, 15 Mgal/d from the Englishtown and 

Wenonah-Mount Laurel aquifers, and 15 Mgal/d from minor 

aquifers of Quaternary age. 

Withdrawals have caused large cones of depression in the 

artesian heads of several aquifers. The deepest parts of the 

Potomac-Rari tan-Magothy cone of depression occur in Camden 

and lVIiddlesex Counties; however, widespread diversions from 

this aquifer have caused water-level declines throughout most 

of the New Jersey Coastal Plain. The cones of depression in 

the Englishtown and Wenonah-Mount Laurel aquifers are 

centered largely in Monmouth County in east-central New 

Jersey whereas the cone of depression in the Kirkwood aquifer 

is largely along the southern coast of New Jersey in Atlantic 

and Cape May Counties. 

Other problems in the New Jersey Coastal Plain are 

saltwater intrusion, which has been noted in Monmouth County 

and in Cape May County at the southern tip of New Jersey, and 

ground-water pollution resulting from industrial and 

municipal waste disposal. 

The program of ground-water investigations in New Jersey 

has been carried out largely in cooperation with the ·Naw 

Jersey Department of Environmental Protection (NJDEP), 

Divis ion of Water Resources. Most aspects of this program 

relate directly to the subregional project as knowledge of 

the hydrogeology, ground-water withdrawals, water levels, and 

of saltwater intrusion result from this program. Computer 

simulation models of several of the principal aquifers have 

been developed under the cooperative program and development 

21 
of a model of the Cohansey Sand aquifer in cooperation with 

both NJDEP and the u.s. Army Corps of Engineers is in 

progress. Development of a multi-layer steady-state model of 

the entire New Jersey Coastal Plain was started in 

cooperation with the NJDEP. St~dies of water quality in the 

Potomac-Raritan-Magothy aquifer system and of subsidence are 

scheduled to start or are in progress. 

Geologic, hydrologic, and geochemical data will be 

compiled and a computerized data file for automatic storage 

and retrieval will be developed. Hydrogeologic and 

geochemical maps will be developed and provided to the 

regional study team. New data, including water-quality 

samples, will be collected. Sensitivity analysis and inverse 

techniques applied to computer simulation modeling will be 

used to evaluate unknown or poorly known aquifer properties. 

Two computer simulation models are planned. The first, 

a steady-state model of the entire New Jersey Coastal Plain 

started in cooperation with the NJDEP, will simulate the five 

princi'pal and three minor aquifers by ten model layers and 

will employ between 1 , 000 and 3, 000 nodes per model layer. 

The second model will be a transient model similar in size 

and number of nodes to the steady-state model, although a 

coarser grid spacing may be necessary because of the added 

complexity of simulating transient leakage from confining 

units. 

Results of this investigation will be presented in three 

reports: (1) a U.S. Geological Survey Water Resources 

Investigation (WRI) report presenting the steady-state model 

and the hydrogeologic maps used to develop the model; (2) a 

U.S. Geological Survey Professional Paper chapter on the 

transient model of, the New Jersey Coastal Plain; and (3) a 

U.S. Geological Survey WRI on the detailed transient model of 

the Potomac-Raritan-Magothy aquifer system. 

22 
New York 

The Atlantic Coastal Plain of New York occurs primarily 

on Long Island, an area of approximately 1 ,400 s~uare miles. 

Coastal Plain sedimments are primarily of Pleistocene and 

Cretaceous age. Th-ey dip to the south and southeast and 

attain a maximum thickness of about 2, 000 feet along the 

south central shore. The three principal a~uifers (see 

figure 6), from youngest to oldest, are the Upper Glacial a~uifer of Pleistocene age, the Magothy a~uifer of Late 

Cretaceous age, and the Lloyd a~uifer of Late Cretaceous age. 

Groundwater pum~age is about 500 Mgal/d distributed as 

follows: 110 Mgal/ d from the Upper Glacial a~uifer, 365 

Mgal/d from the Magothy a~uifer, and 25 Mgal/d from the Lloyd 

aquifer. Pumpage locally exceeds recharge in central Queens 

County and southw~stern Nassau County where extensive cones 

of depression exist and the freshwater supply is threatened 

by saltwater intrusion. 

Groundwater investigations in Long Island have been 

carried out in cooperation with the Nassau County Department 

of Public Works, Suffolk County Water Authority, and Suffolk 

County Department of Health Services. These investigations 

resulted in development of both a five-layer computer 

simulation model and a five-layer electric analog model of 

the Long Island aquifer system. 

The computer simulation model will be modified for this 

project as follows: ( 1) a two-dimensional model of the Lloyd 

aquifer will be developed; this model will have 2, 000 nodes 

and a 6,000 foot grid spacing; (2) the Lloyd a~uifer will be 

added to the five-layer model resulting in a six layer, 

12,000 node model; (3) a finer-grid six-layer model having a 

3,000 foot grid spacing will be developed for western Long 

Island (Kings and Queens Counties). A significant aspect of 

the western Long Island modeling effort will be a study of 

the relation of the hydrogeology of western Long Island to 

that of Monmouth an~ Middlesex Counties, New Jersey. 

Four reports are planned for this study: a U.S. 

Geological Survey Water Resources Investigation (WRI) report 

documenting each of the three developed models and a U.S. 

Geological Survey Professional Paper chapter describing the 

entire study of the Long Island a~uifer system. 

23 
North Carolina 

Coastal Plain aquifer system underlies about 25,000 

square miles in North Carolina and is the major source of 

freshwater in the North Carolina Coastal Plain. Coastal 

Plain sediments ranging in age from Cretaceous to Holocene, 

thicken eastward from a featheredge at the western limit of 

the Coastal Plain to about 10,000 feet at Cape Hatteras. Six 

hydrogeologic units (see figure 6) have been identified in 

the Coastal ·Plain. From youngest to oldest, these are a 

surficial hydrogeologic unit of post-Miocene age, the 

Yorktown hydrogeologic unit which includes sediments of 

Pliocene and Miocene age, the Castle Hayne hydrogeologic unit 

composed of limestone of Eocene and Oligocene age, the 

Beaufort hydrogeologic unit of Paleocene age, the PeedeeBlack Creek hydro ologic unit of Late Cretaceous age, the 

Tuscaloosa hydrogeologic unit which includes the Cape Fear 

Formation of Late Cretaceous age, and unnamed beds of Early 

to Late Cretaceous age. 

Withdrawal from these Qnits for municipal and industrial 

use (including phosphate-mine dewatering) and some irrigation 

is estimated at 1 55 Mgal/ d. About 95 lVIgal/ d is withdrawn 

from the Castle Hayne unit, most of it from phosphate mine 

dewatering in Beaufort County, and about 60 Mgal/d from the 

u n i t s o f C r e t a c e o us age . lVJ. any y e a r s o f g r o u n d-w at e r 

withdrawal have resulted in extensive cones of depression in 

the Castle Hayne unit in Beaufort and surrounding counties 

and in hydrogeologic units of Cretaceous age in Halifax, 

Lenoir, and Craven Counties. Pumping in the vicinity of 

}'ranklin, Virginia has created a large cone of depression 

that extends into rth Carolina, influencing water levels in 

the 1600 sq_uare miile area north of Albermarle Sound. 

twater has moved into previously freshwater parts of the 

Castle unit in response to dewatering in Beaufort 

County. 

The North Carolina Department of Natural Resources and 

Community Development (DNRCD) is conducting a program of data 

collection that includes test drilling, geologic and 

geophysical logging, aquifer testing, and observation wells 

in order to define the stratrigraphy and hydrogeology of the 

Coastal Plain. Detailed studies by DNRCD in selected areas 

in Beaufort, Lenoir, and Craven Counties include water-use 

data collection, aq_ui fer tests, and analysis of streamflow. 

The North Carolina District and DNRCD are cooperating in the 

National Water Use Data Study and in a comprehensive 

observation well network. 

The North Carolina District will collect and compile 

geologic, hydrologic, and geochemical data. Major sources of 

these data are in the files of the U.S. Geological Survey and 

24 
North Carolina water agencies. Pumpage data will be obtained 

largely through a concurrent water use data study. Maps of 

hydrogeologic and geochemical parameters will be compiled for 

each of six hydrogeologic units. Collection of new data to 

fill information gaps will be coordinated with the DNRCD 

program. 

Steady-state and transient computer models simulating 

the six hydrogeologic units by about eight model layers will 

be developed to analyze the North Carolina Coastal Plain 

aquifer system. The models will employ about 3,000 nodes per 

model layer and have a grid spacing of about 3 miles on a 

side. Closer grid spacing may be used in some areas of large 

ground-water withdrawal such as in Beaufort, Halifax, Lenoir, 

and Craven Counties. 

Three reports are planned: a U.S. Geological Survey 

Water Resources Investigation (WRI) report containing 

hydrogeologic data; a U.S. Geological Survey Professional 

Paper chapter on the North Carolina computer simulation 

models; and a WRI report on the effects and management of 

large withdrawals from the Cretaceous aquifer in Lenoir and 

Craven Counties. 

Virginia 

The Atlantic Coastal Plain of Virginia is an area of 

about 13,000 square miles underlain by deposits of sand, 

silt, and clay ranging in age from Cretaceous or older to 

Quaternary. The sediments dip to the southeast at 10 to 50 

feet per mile and thicken southeastward from a featheredge at 

the western limit of the Coastal Plain to about 6,500 feet on 

the Delmarva Peninsula. Four principal aquifers (see figure 

6) have been identified in Virginia. These are, from 

youngest to oldest: the Quaternary aquifer, the Chesapeake 

aquifer of Miocene and Pliocene age, the aquifer of Late 

Cretaceous age sediments, and the aquifer of undifferentiated 

Cretaceous sediments. 

Withdrawal from these units is estimated at 145 Mgal/ d 

but almost all of it, 140 Mgal/d, is from the undifferentiated Cretaceous aquifer. Pumpage from four communities, 

Franklin, Williamsburg, Suffolk, and West Point, accounts for 

80 Mgal/d from this aquifer. 

25 
The long-term utility of the aquifer of undifferentiated 

Cretaceous sediments is being threatened by declining water 

levels and by the occurrence of saltwater in coastal areas. 

Concentrated ground-water withdrawals at Franklin, Suffolk, 

Williamsburg, and West Point in southeastern Virginia have 

caused the expansion and coalescence of several cones of 

depression that extend into northeastern North Carolina. 

Reduction in hydraulic head in clay confining beds has 

resulted in land subsidence in the Franklin area. The State 

of Virginia has identified southeastern Virginia and the 

Eastern Shore as areas of potentially critical water 

shortages. 

Geologic, hydrologic,. and geochemical data will be 

compiled and analyzed and will form the basis of 

hyd roge o logic and geochemical maps. New data wi 11 be 

collected and analyzed to improve and refine the maps, 

particularly in areas of major data deficiencies such as the 

Northern Neck Peninsula in east-central Virginia. 

Steady-state and transient computer simulation models 

will be developed for the Virginia Coastal Plain and will 

extend southward to Albemarle Sound in North Carolina. The 

models will probably simulate the four principal and two 

minor aquifers by about eight model layers and have 2,000 to 

4,000 nodes per model layer. Variable grid spacing will be 

used; the finer grids covering areas of significant 

hydrologic stress. 

Findings of the study will be presented in a U.S. 

Geological Survey Professional Paper chapter at the 

conclusion of the study. Preliminary findings, published as 

op~n-file reports, U.S. Geological Survey Water Resources 

Investigations (WRI), and journal articles, will contain data 

compilations, hydrogeologic maps, and cover special topics 

such as computer simulation modeling and occurrence of saline 

ground water. 

26 
SELECTED REFERENCES 

Brown, P.M., 1959, Geology and ground-water resources in the 

Greenville area, North Carolina: North Carolina 

Department of Conservation and Development Bulletin no. 

73, 87 P· 

Brown, P.M., Miller, J. A., and Swain, F. M., 1972, 

Structural and stratigraphic framework, and spatial 

distribution of permeability of the Atlantic Coastal 

Plain, North Carolina to New York: U.S. Geological 

Survey Professional Paper 796, 79 p. 

Cushing, E. M., Kantrowitz, I. H., and Taylor, K. P., 1973, 

Water resources of the Delmarva Peninsula: U.S. 

Geological Survey Professional Paper 822, 58 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 76-76, 146 p. 

Franke, 0. L., and McClymonds, N. E., 1972, Summary of the 

hydrologic situation on Long Island, New York, as a 

guide to water-management alternatives: U.S. Geological 

Survey Professional Paper 627-F, 59 p. 

Hathaway, J. C., 1976, Preliminary summary of the 1976 

Atlantic Margin coring project of the U.S. Geological 

Survey: U.S. Geological Survey Open-file report 76-844, 

217 p. 

Perry, W. J., Jr., Minard, J. P., Weed, E. G. A., Robbins, E. 

I., and Rhodehamel, E. C., 1975, Stratigraphy of 

Atlantic Coastal Margin of United States north of Cape 

Hatteras - brief survey: American Association of 

Petroleum Geologists Bulletin, v. 59, no. 9, p. 

1529-1548. 

Sumsion, C. T., 1970, Geology and ground-water resources of 

Pitt County, North Carolina: North Carolina Department 

of Water and Air Resources Ground Water Bulletin no. 18, 

75 P· 

Ward, L. W., Lawrence, D. R., and Blackwelder, B. W., 1978, 

Stratigraphic revision of the Middle Eocene, Oligocene, 

and Lower Miocene - Atlantic Coastal Plain of North 

Carolina: U.S. Geological Survey Bulletin 1457-F, 23 p. 

27