Cover.  Aerial photograph of the southern tip of St. Marys County. Point Lookout is to the far left.
Hydrogeology of the Piney Point-Nanjemoy, 

Aquia, and Upper Patapsco Aquifers, 

Naval Air Station Patuxent River and 

Webster Outlying Field, St. Marys County, 

Maryland, 2000–06

By Cheryl A. Klohe and Robert T. Kay

Prepared in cooperation with the

Naval Air Station Patuxent River

Scientific Investigations Report 2006–5266

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2007

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Suggested citation:

Klohe, C.A., and Kay, R.T., 2007, Hydrogeology of the Piney Point-Nanjemoy, Aquia, and Upper Patapsco aquifers, 

Naval Air Station Patuxent River and Webster Outlying Field, St. Marys County, Maryland, 2000–06: U.S. Geological 

Survey Scientific Investigations Report 2006–5266, 26 p.
iii

Contents

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

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

Background............................................................................................................................................3

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

Study Area and Well-Numbering System.........................................................................................3

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

Hydrogeologic Framework...........................................................................................................................7

Surficial Aquifer....................................................................................................................................7

Upper Confining Unit ............................................................................................................................7

Piney Point-Nanjemoy Aquifer...........................................................................................................7

Middle Confining Unit...........................................................................................................................8

Aquia Aquifer.........................................................................................................................................8

Lower Confining Unit............................................................................................................................9

Upper Patapsco Aquifer......................................................................................................................9

Ground-Water Withdrawals and Water Levels ......................................................................................12

Piney Point-Nanjemoy Aquifer.........................................................................................................12

Aquia Aquifer.......................................................................................................................................15

Upper Patapsco Aquifer....................................................................................................................17

Transmissivity of the Upper Patapsco Aquifer........................................................................................21

Ground-Water Quality in the Upper Patapsco Aquifer..........................................................................22

Summary and Conclusions.........................................................................................................................24

Acknowledgments.......................................................................................................................................24

References Cited..........................................................................................................................................24

Figures

1–3. Maps showing:

1. Location of Naval Air Station Patuxent River and Webster Outlying Field 

study areas, approximate outcrop areas of the Aquia and Patapsco 

aquifers, and approximate up-dip extent of the Piney Point-Nanjemoy 

aquifer, southern Maryland................................................................................................2

2. Well locations at Naval Air Station Patuxent River and Webster Outlying 

Field, southern Maryland....................................................................................................4

3. Location of wells shown in hydrogeologic sections A-A’ and B-B’ in 

southern Maryland ..............................................................................................................9

4a–5. Graphs showing:

4a. Hydrogeologic section A-A’ in St. Marys County, Maryland......................................10

4b. Hydrogeologic section B-B’ in St. Marys County, Maryland......................................11

5. Water levels for selected wells screened in the Piney Point-Nanjemoy 

aquifer at Naval Air Station Patuxent River, Maryland, 1998–2006 ...........................14

6. Map showing altitude of water levels in the Piney Point-Nanjemoy aquifer 

on April 28, 2006, Naval Air Station Patuxent River, Maryland............................................16
iv

7. Graph showing water levels for selected wells screened in the Aquia aquifer 

at Naval Air Station Patuxent River (NASPR) and Webster Outlying Field (WOLF), 

Maryland, 1943–2006..................................................................................................................17

8. Map showing altitude of water levels in the Aquia aquifer on April 28, 2006, 

Naval Air Station Patuxent River, Maryland...........................................................................18

9. Graph showing water levels for selected wells screened in the Upper Patapsco 

aquifer at Naval Air Station Patuxent River (NASPR) and Webster Outlying Field 

(WOLF), Maryland, 1978–2006...................................................................................................19

10. Map showing altitude of water levels in the Upper Patapsco aquifer on 

April 28, 2006, Naval Air Station Patuxent River and Webster Outlying Field, 

Maryland ......................................................................................................................................20

11–12. Graphs showing:

11. Analysis of time-drawdown data for well SM Df 100 at Naval Air Station 

Patuxent River, Maryland, August 8–12, 2000 ...............................................................21

12. Analysis of time-drawdown data for well SM Ff 65 at Webster Outlying Field, 

Maryland, August 6–7, 2001 .............................................................................................22

Tables

1. Records for selected wells at Naval Air Station Patuxent River and Webster 

Outlying Field, Maryland..............................................................................................................5

2. Hydrogeologic units and corresponding geologic units at Naval Air Station 

Patuxent River and Webster Outlying Field, Maryland ..........................................................8

3. Ground-water withdrawal at Naval Air Station Patuxent River and Webster 

Outlying Field, Maryland, 1946–2005........................................................................................13

4. Ground-water withdrawal from aquifers in parts of St. Marys and Calvert 

Counties, Maryland, 1980–2004 ................................................................................................14

5. Concentrations of constituents in ground water from wells SM Df 100 and 

SM Ff 65 at Naval Air Station Patuxent River and Webster Outlying Field, 

Maryland, 2000–01......................................................................................................................23
Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 0.4047 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

Volume

gallon (gal) 3.785 liter (L)

Flow rate

foot per year (ft/yr) 0.3048 meter per year (m/yr)

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

gallon per day (gal/d) 0.003785 cubic meter per day (m3/d)

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

Transmissivity*

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

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

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

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

*Transmissivity: The standard unit for transmissivity is cubic foot per day per square foot 

times foot of aquifer thickness [(ft3/d)/ft2]ft. In this report, the mathematically reduced form, foot 

squared per day (ft2/d), is used for convenience.

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius 

(μS/cm at 25°C).

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

or micrograms per liter (μg/L).

Conversion Factors

Abstract

Recent and projected population growth in southern 

Maryland continues to bring ground-water-quality and 

quantity issues to the forefront. Lithologic, borehole 

geophysical, water-level, and water-use data were compiled 

and interpreted to revise understanding of the hydrogeologic 

framework of the Piney Point-Nanjemoy, Aquia, and Upper 

Patapsco aquifers in southern Maryland, with emphasis on the 

Naval Air Station Patuxent River and Webster Outlying Field. 

Understanding of the hydrogeologic framework for the Upper 

Patapsco aquifer also has been revised based on the results of 

aquifer testing and water-quality sampling of two wells.

The Piney Point-Nanjemoy aquifer is 50 to 70 feet 

thick, with a top altitude of 213 to 260 feet below the North 

American Vertical Datum of 1988 and a hydraulic conductivity 

of 2 feet per day at Naval Air Station Patuxent River and 

Webster Outlying Field. Ground-water withdrawals from the 

Piney Point-Nanjemoy aquifer have been minimal since 1999 

and water levels in the aquifer have not changed substantially 

since the 1950s. An overall decline of about 2.5 feet has been 

observed since 1997, however.

The Aquia aquifer is 100 to 145 feet thick, with a top 

altitude of approximately 450 feet below the North American 

Vertical Datum of 1988 and a hydraulic conductivity of 6 to 

10 feet per day at Naval Air Station Patuxent River. The Aquia 

aquifer is approximately 50 feet thick, with a top altitude of 

470 feet below sea level and a hydraulic conductivity of 6 to 

10 feet per day at Webster Outlying Field. Water levels in the 

Aquia aquifer declined in response to increased withdrawals 

from the aquifer from the early 1940s through about 2000 at 

Naval Air Station Patuxent River and Webster Outlying Field, 

but have been generally stable from about 1999 through 

April 2006.

The Upper Patapsco aquifer at the Naval Air Station 

Patuxent River and Webster Outlying Field consists of layers 

of sand interbedded with layers of clay that total over 200 feet 

in thickness. The top of the aquifer near Naval Air Station 

Patuxent River and Webster Outlying Field ranges from 

approximately 620 to 680 feet below the North American 

Vertical Datum of 1988. The potentiometric surface of the 

Upper Patapsco aquifer near Naval Air Station Patuxent River 

and Webster Outlying Field has been declining at a rate of 

about 2 feet per year for the past several years. Aquifer testing 

indicates the transmissivity of the aquifer is about 2,100 to 

3,900 feet squared per day. Water samples collected from the 

Upper Patapsco aquifer at Naval Air Station Patuxent River 

and Webster Outlying Field in 2000 and 2001 met all Federal 

drinking-water standards.

Introduction

Development at the Naval Air Station Patuxent River 

(NASPR) and in the suburban Washington, D.C. area (approximately 50 miles northwest of the air station) has resulted in 

rapid population growth in southern Maryland, especially in 

St. Marys, Charles, and Calvert Counties (fig. 1). This population increase has caused an increase in water use, which has 

been met by increased withdrawals from ground water.

Ground-water withdrawals have resulted in deep cones 

of depression in water-supply aquifers in parts of southern Maryland. At Lexington Park near NASPR (fig. 1), for 

example, the potentiometric surface of the Aquia aquifer 

in 2003 was approximately 100 ft (feet) lower than in 1982 

(Curtin and others, 2005a) and the potentiometric surface of 

the Upper Patapsco aquifer in 2003 was approximately 25 ft 

lower than in 1990 (Curtin and others, 2005b). Achmad and 

Hansen (1997) simulated ground-water levels in the Piney 

Point-Nanjemoy and Aquia aquifers in southern Maryland 

until the year 2020, estimating future ground-water withdrawals from population projections. The simulations show that 

the potentiometric surface near Lexington Park could be as 

low as -95 ft NAVD 88 (North American Vertical Datum of 

1988) in the Piney Point-Nanjemoy aquifer, and -235 ft NAVD 

88 in the Aquia aquifer. This potentiometric surface is about 

Hydrogeology of the Piney Point-Nanjemoy, Aquia, and 

Upper Patapsco Aquifers, Naval Air Station Patuxent 

River and Webster Outlying Field, St. Marys County, 

Maryland, 2000–06

By Cheryl A. Klohe and Robert T. Kay
Figure 1. Location of Naval Air Station Patuxent River and Webster Outlying Field study areas, approximate outcrop 

areas of the Aquia and Patapsco aquifers, and approximate up-dip extent of the Piney Point-Nanjemoy aquifer, 

southern Maryland.

   Hydrogeology of Selected Confined Aquifers, Naval Air Station Patuxent River, Maryland, 2000–06
100 ft lower than pre-pumping conditions in the Piney PointNanjemoy aquifer and about 250 ft lower than pre-pumping 

conditions in the Aquia aquifer near Lexington Park. This 

potentiometric surface also is about 70 ft lower than that measured in the Piney Point-Nanjemoy aquifer at NASPR during 

April 2006 and at least 100 ft lower than that measured in the 

Aquia aquifer at NASPR during April 2006. As a result, many 

County and State water managers, private citizens, and air station officials are interested in the optimization of water supply 

from the Piney Point-Nanjemoy, Aquia, and Patapsco aquifers 

in southern Maryland.

The U.S. Geological Survey (USGS), in cooperation with 

NASPR, investigated the hydrogeology and water quality of 

the Piney Point-Nanjemoy and Aquia aquifers in the vicinity 

of NASPR and Webster Outlying Field (WOLF) (fig. 1) 

from 1998 through 2000 (Klohe and Feehley, 2001). That 

investigation was performed to help understand the effects of 

the water-use practices at NASPR and WOLF on the water 

resources of the area. Since 2000, the USGS, in cooperation 

with NASPR, has collected additional data on water levels and 

water use in the Piney Point-Nanjemoy and Aquia aquifers. In 

addition, the USGS and NASPR have collected data on water 

levels and water use from the Upper Patapsco aquifer in the 

vicinity of NASPR and WOLF, and conducted aquifer tests 

and water-quality sampling in wells screened in the Upper 

Patapsco aquifer at NASPR and WOLF. This report presents 

an update of the data collected from these aquifers in the 

vicinity of NASPR and WOLF and includes data collected 

from March 2000 through May 2006.

Background

NASPR was commissioned in 1943 as part of an effort 

to centralize U.S. Navy facilities. WOLF, near St. Inigoes, 

Maryland, serves as an auxiliary landing field for NASPR. 

Testing and development of aircraft and weaponry at NASPR 

and WOLF increased during the Korean and Vietnam Wars 

and continues today. During the 1990s, the Navy began 

consolidating their technical resources and NASPR became 

a receiver station as a result of base realignment and closure 

of other facilities (Naval Air Station Patuxent River, 2000). 

As a result of this consolidation, the number of personnel at 

NASPR and WOLF decreased from about 10,000 employees 

in 1981, to 13,000 in 1996, 18,000 in 1998, and approximately 

20,000 in 2006 (James Darcy, Public Affairs Office, Naval 

Air Station Patuxent River, written commun., 2006).

Purpose and Scope

This report describes the hydrogeologic framework of the 

Piney Point-Nanjemoy, Aquia, and Upper Patapsco aquifers 

at NASPR and WOLF and the surrounding area. Analyses of 

water levels in the Piney Point-Nanjemoy, Aquia, and Upper 

Patapsco aquifers and the relation between water levels and 

ground-water withdrawals from the aquifers are presented 

on the basis of data collected from 1943 through 2006. In 

addition, this report presents the results of aquifer testing and 

water-quality sampling from two wells screened in the Upper 

Patapsco aquifer at NASPR and WOLF in 2000 and 2001. The 

hydrogeology of the area is described on the basis of information from previous reports, State of Maryland permits to 

drill, State of Maryland well completion reports, and USGS 

historical well files that include water levels, geophysical 

logs, and well-construction data. The water-level data are 

from the USGS National Water Information System (NWIS) 

database. Ground-water-withdrawal records were obtained 

from correspondence between the USGS and NASPR in the 

1940s, 1950s, and 1970s, and from continuous records kept by 

the air station from 1989 through April 2006. Ground-waterwithdrawal data for southern Maryland were obtained from the 

USGS State Water-Use Data System (SWUDS) database and 

the Maryland Department of the Environment (MDE) Regulatory Analysis Management System (RAMS) database.

Study Area and Well-Numbering System

NASPR is in southern Maryland in St. Marys County, 

southwest of the convergence of the mouth of the Patuxent 

River and Chesapeake Bay (fig. 1). WOLF is southwest of 

NASPR, on the St. Marys River near St. Inigoes, Maryland 

(fig. 1). The locations of the wells discussed in this report 

are shown in figure 2. Data on well construction is presented 

in table 1. Most of the wells are production wells, or were 

production wells that have been abandoned or converted to 

observation wells. In this report, wells are listed by their 

USGS identification number. For example, well SM Df 14 is a 

well located in St. Marys County, indicated by the first two letters “SM;” in the 5-minute quadrangle “Df,” indicated by the 

second two letters; and is the 14th well mapped in the quadrangle, indicated by the last two numbers “14.” The 5-minute 

quadrangles are designated by uppercase letters from north to 

south (A through F in St. Marys County), and lowercase letters 

from west to east (a through h in St. Marys County).

Previous Investigations

In 1944, the Commanding Officer of NASPR asked the 

USGS to collect information on the availability of ground 

water at the naval establishments in the vicinity of Solomons 

and NASPR (fig. 1). Bennett (1944) compiled available well 

records, ran brief aquifer tests, and measured static and pumping water levels in some wells. This study provides insight into 

the hydrogeologic properties of the Piney Point-Nanjemoy and 

Aquia aquifers and water withdrawals from these aquifers at 

and near NASPR in the early 1940s.

Since 1982, the USGS has published maps of the 

potentiometric surface of the Aquia aquifer in southern 

Maryland. Each year, the maps have shown an increase in the 

size and depth of the cone of depression in the potentiometric 

surface of the Aquia aquifer near Lexington Park, Maryland. 

Introduction 
Figure 2. Well locations at Naval Air Station Patuxent River and Webster Outlying Field, southern Maryland.

 Hydrogeology of Selected Confined Aquifers, Naval Air Station Patuxent River, Maryland, 2000–06
Table 1. Records for selected wells at Naval Air Station Patuxent River and Webster Outlying Field, Maryland.

[USGS, U.S. Geological Survey; no., number; NAVD 88, North American Vertical Datum of 1988; --, no data available; n/a, not applicable; geophysical log types - G, Gamma; SP, Spontaneous Potential; R, Resistance; SN, Short Normal; LN, Long Normal]

USGS 

well no.

Altitude 

of land 

surface 

(feet above 

NAVD 88)

Aquifer

Depth of 

well 

(feet below land 

surface)

Well 

diameter 

upperlower 

(inches)

Screen position 

(feet below land surface)

Date of 

construction

State of 

Maryland 

well 

permit no.

Driller

SM Df 1 93 Aquia 587 8 567–587 1943 -- Washington Pump and Well Co.SM Df 10 45 Aquia 534 8–6 514–534 1943 -- Washington Pump and Well Co.SM Df 14 18 Piney Point-Nanjemoy 262 8 -- 1943 -- Washington Pump and Well Co.SM Df 43A 39 Aquia 553 8 514–534 9/1/1955 -- Syndor Pump and Well Co.SM Df 61 108 Aquia 600 8–6 580–600 1964 SM-05-5823 Patuxent Pump and Well Co.SM Df 93 41 Aquia 567 8–6 515–565 4/7/1994 SM-92-0358 A.C. Schultes of MarylandSM Df 94 99 Aquia 612 8–6 560–610 4/12/1994 SM-92-0357 A.C. Schultes of MarylandSM Df 95 79 Aquia 582 8–6 530–580 4/24/1994 SM-92-0369 A.C. Schultes of MarylandSM Df 96 8 Aquia 539 8–6 489–539 11/10/1994 SM-93-0036 A.C. Schultes of MarylandSM Df 97 46 Aquia 568 8–6 515–565 9/22/1997 SM 94-0925 A.C. Schultes of MarylandSM Df 98 80 Aquia 575 8–6 525–575 12/15/1996 SM 94-0410 A.C. Schultes of MarylandSM Df 99 44 Aquia 600 16–8 490–600 11/8/1994 SM 92-0642 Vans Construction Co.SM Df 100 20 Upper Patapsco 910 10–8 706–716, 744–754, 835–860, 

882–892, 900–905

8/4/2000 SM-94-3113 A.C. Schultes of Maryland

SM Dg 1A 18 Aquia 480 8 460–480 1943 -- Washington Pump and Well Co.SM Dg 4 19 Piney Point-Nanjemoy 295 2 275–295 1949 SM-00-3978 Washington Pump and Well Co.SM Dg 5 21 Aquia 494 8 469–488.5 1950 -- Washington Pump and Well Co.SM Dg 9A,B 19 Aquia 586 n/a n/a 9/1972 SM-73-0095 Shannahan Artesian Well Co.SM Dg 11A 9 Piney Point-Nanjemoy 290 6 280–290 4/23/1980 -- Calvert Well Drilling Co.SM Dg 14 18 Aquia 542 8–6 490–540 4/22/1994 SM-92-0370 A.C. Schultes of MarylandSM Dg 15 20 Aquia 500 8–5 450–500 12/17/1993 SM-92-0570 Patuxent Pump and Well Co.SM Dg 16 11 Aquia 520 8–6 470–520 11/19/1996 SM-94-0411 A.C. Schultes of MarylandSM Dg 17 19 Aquia 591 12–8 481–591 7/15/1995 SM-92-0643 Vans Construction Co.SM Dg 18 17 Aquia 553 8–6 503–553 10/15/1997 SM-94-0926 A.C. Schultes of Maryland

Introduction 
Table 1. Records for selected wells at Naval Air Station Patuxent River and Webster Outlying Field, Maryland.—Continued

[USGS, U.S. Geological Survey; no., number; NAVD 88, North American Vertical Datum of 1988; --, no data available; n/a, not applicable; geophysical log types - G, Gamma; SP, Spontaneous Potential; R, Resistance; SN, Short Normal; LN, Long Normal]

USGS 

well no.

Altitude 

of land 

surface 

(feet above 

NAVD 88)

Aquifer

Depth of 

well 

(feet below land 

surface)

Well 

diameter 

upperlower 

(inches)

Screen position 

(feet below land surface)

Date of 

construction

State of 

Maryland 

well 

permit no.

Driller

SM Dg 19 9 Aquia 532 12–8 480–510 6/23/1988 SM-81-3345 Syndor Pump and Well Co.

SM Dg 20 11 Piney Point-Nanjemoy 335 4–2 325–335 2/15/1991 SM-88-0946 Watson & Johnson Well Drilling, Inc.SM Dg 21 2 Piney Point-Nanjemoy 315 4 295–315 6/18/1996 SM-94-0074 Southern Well and Recovery Corp.SM Dg 22 11 Piney Point-Nanjemoy -- -- -- -- -- --SM Ff 21 8 Aquia 486 8 464–486 8/13/1945 -- Washington Pump and Well Co.SM Ff 35 4 Aquia 537 8–4 487–537 8/8/1975 SM-73-1496 A.C. Schultes of MarylandSM Ff 62 9 Aquia 539 8–6 486–536 2/20/1998 SM-94-1128 A.C. Schultes of MarylandSM Ff 63 9 Aquia 545 -- -- -- -- --SM Ff 64B 9 Aquia 534 -- -- -- -- --SM Ff 65 9 Upper Patapsco 884 10–8 635–640, 648–658, 689–694, 

782–792, 846–856, 864–874

8/10/2001 SM-94-3700 A.C. Schultes of Maryland

Wells outside of Naval Air Station Patuxent River and Webster Outlying Field, Maryland

SM Ff 36 5 Upper Patapsco 618 8–6 594–618 10/29/1975 SM-73-1478 A. MirfieldSM Ff 37 4 Upper Patapsco 618 4–2 594–618 8/29/1975 SM-73-1479 A. MirfieldSM Df 84 108 Upper Patapsco 912 6–4 831–856, 862–867, 897–912 1/5/1983 SM-81-0119 A.C. Schultes of Maryland

A Well no longer exists.B Test hole.

   Hydrogeology of Selected Confined Aquifers, Naval Air Station Patuxent River, Maryland, 2000–06
Chappelle and Drummond (1983) described the Piney PointNanjemoy and Aquia aquifers in southern Maryland, but did 

not include detailed information in the vicinity of NASPR and 

WOLF. Chapelle and Drummond (1983) included results of 

ground-water-flow simulations and described the chemical 

evolution of water in the Aquia and Piney Point-Nanjemoy 

aquifers in southern Maryland. Achmad and Hansen (1997) 

also described ground-water flow simulations of the Piney 

Point-Nanjemoy and Aquia aquifers. Assuming the amount of 

water pumped from the aquifers each year is equal to the 1995 

maximum Ground-Water Appropriation Permit rates, Achmad 

and Hansen’s simulations predict that water levels in the Aquia 

aquifer will average -235 ft from (negative values indicate 

below) sea level (the vertical datum for sea level is not defined 

by Achmad and Hansen) by 2020 in NASPR/Lexington 

Park area. At that pumping rate, the simulated water level in 

well SM Df 42 at Lexington Park was about -330 ft, which 

would be within 27 ft of the 80-percent available drawdown 

management level of -357 ft. The 80-percent regional water 

management level is calculated as 80 percent of the available 

drawdown between the top of the aquifer and the pre-pumping 

potentiometric level and is used by the State of Maryland to 

determine the amount of discharge a well can be permitted.

Klohe and Feehley (2001) described the hydrogeologic 

framework, water use, and water quality for the Piney PointNanjemoy and Aquia aquifers at NASPR and WOLF. They 

determined that water withdrawals from the Piney PointNanjemoy aquifer have decreased since about 1975 and water 

levels in the aquifer have been constant since the 1950s. They 

also determined that water withdrawals from the Aquia aquifer 

had decreased at NASPR and WOLF since about 1991, but 

that water levels in the aquifer were still declining in 2000 

in response to increased pumping from nearby municipal 

systems. Water-quality data for both aquifers did not indicate 

saltwater intrusion.

Drummond (2005) discussed the water use and projected 

increases in demands on the water supply of Coastal Plain 

aquifers in Calvert, Charles, and St. Marys Counties, Maryland. Drummond also described two test wells screened in the 

Upper Patapsco aquifer and four wells screened in the Lower 

Patapsco aquifer that were constructed between 2001 and 

2003. Drummond also simulated projected increases in drawdown in the Coastal Plain aquifers within the three counties, 

including those at NASPR. Simulations that increased NASPR 

2002 withdrawal rates by 10 percent and 20 percent from 2002 

to 2030 resulted in a decrease of a few feet in the Lexington 

Park, Maryland area.

Hydrogeologic Framework

The Coastal Plain of southern Maryland is underlain by 

an easterly dipping wedge of sediments composed mainly of 

unconsolidated clay, silt, sand, and gravel (table 2) (figs. 3 and 

4a and 4b). These sediments range in age from Holocene to 

Lower Cretaceous (Chapelle and Drummond, 1983) and crop 

out subparallel to the Fall Line (fig. 1), which is the approximate boundary between the Coastal Plain and the Piedmont 

Physiographic Provinces. The hydrogeologic units discussed 

in this report, from youngest to oldest are: the surficial 

aquifer, the upper confining unit, the Piney Point-Nanjemoy 

aquifer, the middle confining unit, the Aquia aquifer, the lower 

confining unit, and the Upper Patapsco aquifer (table 2).

Surficial Aquifer

The uppermost sediments in the study area are Holocene 

to Pliocene-aged sediments that range from clays and silts to 

sands and gravels (table 2). These sediments are undifferentiated in the vicinity of NASPR and compose the surficial aquifer. The surficial aquifer ranges in thickness from 10 to 100 ft 

in the vicinity of NASPR and WOLF. The surficial aquifer is 

unconfined and was used as a source of water for domestic and 

agricultural uses in the past (Achmad and Hansen, 1997).

Upper Confining Unit

Beneath the Holocene to Pliocene-aged sediments lie 

the clay and silt of the upper part of the Chesapeake Group 

(undivided) of Miocene age (table 2). These clays and silts are 

designated as the upper confining unit, which lies below the 

surficial aquifer and above the unnamed beds of Oligocene or 

Miocene age. The upper confining unit is approximately 210 

to 250 ft thick at NASPR and WOLF.

Piney Point-Nanjemoy Aquifer

Below the upper confining bed lie the basal beds of the 

Chesapeake Group, unnamed Oligocene or Miocene units, the 

Piney Point Formation, and the upper part of the Nanjemoy 

Formation (Achmad and Hansen, 1997) (table 2). The basal 

beds of the Chesapeake Group consist of fine- to mediumgrained, yellowish-green to greenish-light gray quartz sand, 

and are slightly glauconitic with shell fragments, phosphate 

pebbles, and fine gravel (Achmad and Hansen, 1997). The 

unnamed Oligocene or Miocene units consist of clayey 

sands that are brown to olive green, slightly glauconitic, and 

fossiliferous (Achmad and Hansen, 1997). The Piney Point 

Formation consists of medium- to coarse-grained, quartz sands 

that are grayish-green to grayish-white in color, glauconitic, 

and with calcite cemented beds (Chapelle and Drummond, 

1983). The Nanjemoy Formation also is composed of sand 

that is similar to that of the Piney Point Formation. These 

four permeable sand units are hydraulically connected and 

are commonly combined and designated as the Piney PointNanjemoy aquifer. The Piney Point-Nanjemoy aquifer 

underlies the upper confining unit. The elevation of the top of 

the Piney Point-Nanjemoy aquifer ranges from about -213 ft 

NAVD 88 in the western part of NASPR, decreasing to 

Hydrogeologic Framework 
-255 ft NAVD 88 in the eastern part of NASPR, and to 

about -260 ft NAVD 88 to the southeast at WOLF (Klohe 

and Feehley, 2001). The aquifer is approximately 50 to 

70 ft thick, and has a horizontal hydraulic conductivity (Kh) 

of approximately 2 ft/d (feet per day) at NASPR and WOLF 

(Klohe and Feehley, 2001) (figs. 4a and 4b).

The Piney Point-Nanjemoy aquifer is not exposed at the 

land surface; therefore, recharge to the aquifer occurs by percolation from the overlying upper confining unit. The approximate western (updip) extent of the aquifer in the subsurface in 

Maryland is along the northern boundaries of Calvert County, 

and St. Marys County (fig. 1). The eastern (downdip) extent of 

the aquifer runs through southeast Sussex County, Delaware, 

then southwest through central Wicomico County, Maryland, 

and then south through the west side of Somerset County, 

Maryland (Vroblesky and Fleck, 1991).

Middle Confining Unit

The lower part of the Nanjemoy Formation and the 

Marlboro Clay lie beneath the Piney Point-Nanjemoy aquifer 

(table 2). The lower part of the Nanjemoy Formation consists 

largely of greenish-black to olive-black silts and clays. 

The Marlboro Clay consists of pale red or gray plastic clay 

(Achmad and Hansen, 1997). The clays and silts of the two 

formations form the middle confining unit (table 2). The 

thickness of the middle confining unit ranges from 130 to 

150 ft in the vicinity of NASPR and WOLF (figs. 4a and 4b).

Aquia Aquifer

Beneath the middle confining unit lies the Aquia 

Formation. The greenish-black, quartz sand, glauconite, and 

lenses of silty clay and shell beds of the Aquia Formation 

are water-bearing and are designated as the Aquia aquifer 

(table 2) (Chapelle and Drummond, 1983). The elevation of 

the top of the Aquia aquifer is approximately -450 ft NAVD 

88 beneath NASPR and WOLF (Klohe and Feehley, 2001). 

The thickness of the Aquia aquifer decreases from about 100 

to 145 ft at NASPR to about 50 ft at WOLF (fig. 4b). This 

trend in thickness is consistent with regional hydrogeologic 

sections that show the sands of the Aquia Formation nearing 

Table 2. Hydrogeologic units and corresponding geologic units at Naval Air Station Patuxent River and Webster 

Outlying Field, Maryland.

   Hydrogeology of Selected Confined Aquifers, Naval Air Station Patuxent River, Maryland, 2000–06
their lateral extent at WOLF (figs. 1 and 4b). As the Aquia 

Formation continues to the southeast, it becomes thinner, 

finer-grained, and predominately clayey (Achmad and Hansen, 

1997). The Kh of the Aquia aquifer ranges from 6 to 10 ft/d at 

NASPR and WOLF.

The Aquia aquifer is recharged primarily along its 

outcrop (fig. 1). In Maryland, the aquifer crops out in central 

Anne Arundel County, central Prince Georges County, and in 

northwest Charles County near the Potomac River.

Lower Confining Unit

The Brightseat Formation is composed of gray clay and 

fine sand, and the clay beds in the upper part of the Patapsco 

Formation lie beneath the Aquia aquifer. These clay beds are 

designated as the lower confining unit (table 2). The lower 

confining unit is approximately 75 to 175 ft thick in the 

vicinity of NASPR and WOLF (figs. 4a and 4b).

Upper Patapsco Aquifer

Sand units in the Patapsco Formation of the Potomac 

Group lie beneath the lower confining unit. The sand units 

are interbedded with silt and clay units, making the sand units 

variable in thickness and location. The sand beds in the upper 

part of the Patapsco Formation of the Potomac group are 

designated as the Upper Patapsco aquifer, the deepest hydrogeologic unit of concern in this investigation (table 2). The 

discontinuity of the interbedded sand and clay layers makes it 

difficult to determine the bottom of the aquifer; therefore, the 

bottom of the Upper Patapsco aquifer was not delineated as 

part of this investigation (figs. 3, 4a and 4b).

From west to east, the altitude of the top of the 

Upper Patapsco aquifer ranges from -565 ft NAVD 88 at well 

SM Dd 72 near Leonardtown, Maryland to -660 ft at well 

SM Df 100 at NASPR (figs. 3 and 4a). From north to south, 

the altitude of the top of the aquifer ranges from about -687 ft 

Figure 3. Location of wells shown in hydrogeologic sections A-A’ and B-B’ in southern Maryland.

Hydrogeologic Framework 
Figure 4a. Hydrogeologic section A-A’ in St. Marys County, Maryland. (Location of section shown on figure 3.)

10 Hydrogeology of Selected Confined Aquifers, Naval Air Station Patuxent River, Maryland, 2000–06
Figure 4b. Hydrogeologic section B-B’ in St. Marys County, Maryland. (Location of section shown on figure 3.)

Hydrogeologic Framework 11
at well SM De 51 in California, Maryland to about -625 ft at 

WOLF and -600 ft at well SM Ff 36 near Kitts Point, Maryland. Screened intervals for wells SM Ff 65 and SM Df 100 

(table 1) indicate the aquifer is approximately 200 to 240 ft 

thick at NASPR and WOLF, but producing sands are not 

present throughout the aquifer.

Recharge to the Upper Patapsco aquifer occurs primarily 

where the Patapsco Formation outcrops subparallel to the Fall 

Line. In southern Maryland, the outcrop area for the Upper 

Patapsco aquifer extends from near the boundary with Washington, D.C. northeast to the southern edge of Baltimore.

Ground-Water Withdrawals and 

Water Levels

Before 1942, ground-water withdrawals in the area of 

NASPR and WOLF were restricted to small amounts for 

domestic use in the town of Solomons, Maryland (Bennett, 

1944). Substantial ground-water withdrawal in the vicinity 

of NASPR and WOLF began in 1942, when these facilities 

were built. Yearly withdrawal records for NASPR and WOLF 

obtained for this report date back to 1946, but are intermittent 

prior to 1989 (table 3). For each well, monthly withdrawal 

values (in gallons) were summed for a calendar year and then 

divided by the number of days with data for that year to calculate the average daily withdrawal. The monthly withdrawal 

values were either measured with a flow meter or estimated. 

Data collected since 1988 are considered to be more accurate 

because complete withdrawal records were collected and furnished by NASPR employees, whereas prior records may not 

include all withdrawal data.

Average daily withdrawal data from NASPR for the 

period from 2001 through 2005 indicate that withdrawals during the summer months substantially exceed those for the rest 

of the year. During 2001–2005, total withdrawals at NASPR 

averaged about 649,000 gal/d (gallons per day) from January 

through April, about 826,000 gal/d from May through September, and about 623,000 gal/d from October through December.

Personnel data, furnished by the air station’s Public 

Affairs Office, include the number of military, civilian, contractor, and other employees who worked at NASPR and used 

its resources. For this report, military personnel data records 

cover the period from 1962–2006, and total personnel data 

cover the period from 1981–2006. Personnel data for WOLF 

were unavailable. The total number of personnel at NASPR 

increased from 1981 to 2006, with the greatest number of 

people (about 20,000) working at the station in April 2006. 

Overall ground-water withdrawals at NASPR decreased during 

the same period (table 3), as less water was used for industrial 

and heating applications, and improvements were made in the 

water-distribution infrastructure (Donald Shaver, Naval Air 

Station Patuxent River, oral commun., 2000).

In Maryland, large users permitted to withdraw more 

than 10,000 gal/d are required to report monthly withdrawal 

values to State permitting agencies. These reported data are 

then transferred and stored in the USGS SWUDS database. 

Withdrawal values for large users of the aquifers within a 

13-mi (mile) radius of NASPR in parts of both St. Marys and 

Calvert Counties (east of Leonardtown, north of St. Marys 

City, and south of Calvert Cliffs Nuclear Power Plant) were 

retrieved from the SWUDS database. The data indicate that 

total ground-water withdrawals from wells in St. Marys and 

Calvert Counties near NASPR and WOLF increased from 

2.25 Mgal/d (million gallons per day) in 1980 to about 

5.0 Mgal/d during most of 1998 through 2004 (table 4). 

Withdrawals from the Piney Point-Nanjemoy aquifer peaked 

at about 0.75 Mgal/d in 1992 through 1994, decreased to 

about 0.35 Mgal/d in 2001 and 2002, and increased to 

0.559 Mgal/d in 2004. Withdrawals from the Aquia aquifer 

typically have been about 4.3 Mgal/d since 1997. Withdrawals 

from the Upper Patapsco aquifer were less than 0.01 Mgal/d 

prior to 1995, but consistently increased to 0.35 Mgal/d in 

2004. Withdrawals from the Aquia aquifer constituted about 

75 to 83 percent of the total withdrawals from 1980 through 

1994, increasing to about 88 percent of the total withdrawals 

from 1997 through 2003 as withdrawals from the Piney PointNanjemoy aquifer decreased.

Piney Point-Nanjemoy Aquifer

The Piney Point-Nanjemoy aquifer began to be used for 

water supply in the vicinity of NASPR and WOLF in the late 

1800s and early 1900s (Chapelle and Drummond, 1983). Utilization of the aquifer was facilitated by its relatively shallow 

depth and the fact that it was under flowing artesian conditions 

at Solomons, Leonardtown, and St. Inigoes (Darton, 1896). 

Substantial ground-water withdrawals from the Piney PointNanjemoy aquifer began during World War II, when the U.S. 

Navy built several training facilities in the Lexington Park and 

Solomons areas. Substantial withdrawals from the aquifer also 

occurred during the same period outside of the air station to 

support increasing domestic and municipal demands (Chapelle 

and Drummond 1983).

Limited water withdrawal data for NASPR are available 

from 1946 through 1975, but the available data indicate that 

typical withdrawals from the Piney Point-Nanjemoy aquifer 

were about 70,000 to 108,000 gal/d during this time (table 3). 

Withdrawals from the Piney Point-Nanjemoy aquifer were 

less than 100 gal/d from at least 1989 through 1992. There 

was a large increase in withdrawals from 1993 through 1997. 

Since 1999, withdrawals from the Piney Point-Nanjemoy 

aquifer at NASPR have been less than 1,700 gal/d. The lower 

withdrawals are the result of concerns about excessive waterlevel declines in the aquifer. There is no record that water has 

ever been withdrawn from the Piney Point-Nanjemoy aquifer 

at WOLF.

Withdrawals from the Piney Point-Nanjemoy aquifer 

have caused water levels in the NASPR and Lexington Park 

area to decline. Darton (1896) reported Piney Point-Nanjemoy 

12 Hydrogeology of Selected Confined Aquifers, Naval Air Station Patuxent River, Maryland, 2000–06
Table 3. Ground-water withdrawal at Naval Air Station Patuxent River and Webster Outlying Field, Maryland, 1946–2005.

[-, no data available; data prior to 1989 are intermittent]

Year

Average daily withdrawal, in gallons per day

Naval Air Station Patuxent River Webster Outlying Field

Piney PointNanjemoy aquifer Aquia aquifer Upper Patapsco 

aquifer Total Aquia aquifer Upper Patapsco aquifer Total

1946 47,761 1,128,458 0 1,176,219 - 0 -

1947 91,635 1,206,427 0 1,298,062 - 0 -

1948 99,895 1,313,130 0 1,413,025 - 0 -

1949 67,874 1,438,823 0 1,506,697 - 0 -

1953 84,000 1,559,000 0 1,643,000 - 0 -

1954 74,000 1,414,000 0 1,488,000 - 0 -

1955 73,780 1,354,143 0 1,427,923 - 0 -

1956 103,000 1,343,340 0 1,446,340 - 0 -

1970 107,868 1,249,720 0 1,357,588 14,479 0 14,479

1971 133,910 1,153,838 0 1,287,748 16,945 0 16,945

1974 75,916 1,152,264 0 1,228,180 - 0 -

1975 82,231 844,676 0 926,907 - 0 -

1989 93 1,038,654 0 1,038,747 73,705 0 73,705

1990 99 938,988 0 939,087 59,225 0 59,225

1991 99 1,118,700 0 1,118,799 78,390 0 78,390

1992 99 797,223 0 797,322 55,774 0 55,774

1993 55,689 808,236 0 863,925 47,799 0 47,799

1994 178,150 812,360 0 990,510 42,627 0 42,627

1995 43,156 748,439 0 791,595 40,245 0 40,245

1996 45,730 697,497 0 743,227 26,498 0 26,498

1997 58,984 754,685 0 813,669 26,498 0 26,498

1998 1,605 831,382 0 832,987 29,536 0 29,536

1999 24,061 832,636 0 856,697 27,666 0 27,666

2000 888 694,786 0 695,674 27,666 0 27,666

2001 1,392 707,274 0 708,666 28,860 0 28,860

2002 1,336 764,935 0 766,271 3,318 21,255 24,573

2003 1,694 674,248 37,300 713,242 5,060 28,110 33,170

2004 739 661,313 28,858 690,910 11,922 13,688 25,610

2005 714 675,266 17,518 693,498 11,507 8,621 20,128

Data Sources: 

1946 through 1997: Various U.S. Geological Survey and Naval Air Station Patuxent River documents.

1998 through 2005: Michael Oliver, Naval Air Station Patuxent River, written commun., 2006.

Ground-Water Withdrawals and Water Levels 13
aquifer wells flowing 2 to 20 ft above land surface at Solomons, Leonardtown, and St. Inigoes. The wells stopped 

flowing when pumping caused the ground-water levels to 

decline in the mid-1940s (Bennett, 1944; Otton, 1955). Otton 

(1955) also reported the center of a cone of depression in the 

Piney Point-Nanjemoy aquifer at approximately -20 ft around 

NASPR by 1951, with the lowest recorded value of -32 ft 

northwest of well SM Df 43. Williams (1979) reported a water 

level in the Piney Point-Nanjemoy aquifer of -21 ft near well 

SM Df 1 in 1976. A 1980 potentiometric surface map of the 

Piney Point-Nanjemoy aquifer (Chapelle and Drummond, 

1983) shows cones of depression around well fields at NASPR 

and in the Solomons area. The lowest potentiometric levels 

reported for the Piney Point-Nanjemoy aquifer in 1980 were 

-23 and -22 ft, near the southwest border of the main facilities 

at NASPR and the Solomons areas, respectively. Although the 

potentiometric surface of the Piney Point-Nanjemoy aquifer 

at WOLF has not been mapped, pumping in the surrounding 

areas has not led to the formation of an extensive cone of 

depression as of 2004 (Stephen Curtin, U.S. Geological 

Survey, written commun., 2006).

This regional pattern of water levels is consistent with 

water levels in the Piney Point-Nanjemoy aquifer collected 

at NASPR by the USGS (fig. 5). The oldest water-level 

measurement from a well at NASPR screened in the Piney 

Point-Nanjemoy aquifer was taken from well SM Df 14 in 

1944. The water level in 1944 (-26.39 ft NAVD 88) was 

consistent with measurements taken at this well from 1996 

through 1999 (about -24 to -29 ft NAVD 88). Although 

there is a 52-year gap in the record, these data indicate that 

the Piney Point-Nanjemoy water levels in the NASPR area 

did not change appreciably from 1944 through 1999. Well 

SM Df 14 had a collapsed screen in 2002, so more recent 

water-level measurements from this well were not analyzed. 

Water levels measured in wells SM Dg 20, SM Dg 21, and 

SM Dg 22 at NASPR all showed an overall decline in water 

levels in the Piney Point-Nanjemoy aquifer from 1998 through 

2006 of about 2.5 ft, with water levels measured after May 

2002 typically being lower than those measured before that 

date (fig. 5). This overall rate of decline is about 0.3 ft/yr (feet 

per year). Water levels in these wells showed some tendency to 

be lower in late summer than during the rest of the year, which 

may reflect the effects of seasonal variations on the volume of 

withdrawals.

Table 4. Ground-water withdrawal from aquifers in parts of 

St. Marys and Calvert Counties, Maryland, 1980–2004 (Naval Air 

Station Patuxent River and Webster Outlying Field excluded).

Year

Average daily withdrawal, in million gallons per day

Piney PointNanjemoy 

aquifer

Aquia 

aquifer

Upper 

Patapsco 

aquifer

Total

1980 0.49 1.76 0.000 2.25

1981 0.56 1.82 0.000 2.37

1982 0.58 2.06 0.000 2.63

1983 0.56 2.03 0.000 2.59

1984 0.48 2.04 0.000 2.52

1985 0.67 2.13 0.000 2.80

1986 0.74 2.46 0.000 3.20

1987 0.56 2.65 0.000 3.21

1988 0.58 2.67 0.000 3.25

1989 0.62 2.48 0.000 3.10

1990 0.47 2.39 0.000 2.86

1991 0.51 2.85 0.000 3.36

1992 0.74 2.86 0.000 3.60

1993 0.84 3.14 0.000 3.98

1994 0.71 3.40 0.004 4.11

1995 0.69 3.61 0.010 4.31

1996 0.56 3.75 0.017 4.33

1997 0.55 4.09 0.025 4.66

1998 0.52 4.37 0.031 4.92

1999 0.56 4.39 0.017 4.96

2000 0.45 4.22 0.140 4.81

2001 0.34 4.34 0.247 4.93

2002 0.37 5.10 0.196 5.67

2003 0.47 4.53 0.169 5.17

2004 0.56 4.30 0.350 5.21

Data Source:

U.S. Geological Survey State Water-Use Data System, Wendy McPherson, U.S. Geological Survey, written commun., 2006.

Figure 5. Water levels for selected wells screened in the 

Piney Point-Nanjemoy aquifer at Naval Air Station Patuxent 

River, Maryland, 1998–2006.

14  Hydrogeology of Selected Confined Aquifers, Naval Air Station Patuxent River, Maryland, 2000–06
A comparison of trends in water levels in the Piney 

Point-Nanjemoy aquifer at NASPR with rates of withdrawal 

from the aquifer at NASPR (table 3) and the surrounding area 

(table 4) indicates that water levels in the aquifer at NASPR 

are affected by withdrawals from the aquifer at NASPR. 

Water levels in well SM Dg 20, and to a lesser degree, well 

SM Dg 21, were relatively stable in 1998, 2000, and 2001; 

during this period, pumping from the aquifer at NASPR was 

about 1,500 gal/d (fig. 5) (table 3). Water levels in wells 

SM Dg 20 and SM Dg 21 decreased in 1999, when withdrawals from the aquifer at NASPR increased to about 

24,000 gal/d (table 3). The decrease in withdrawals from the 

Piney Point-Nanjemoy aquifer at NASPR from 2002 through 

2005 was coupled with an overall trend of decreasing water 

levels at wells SM Dg 20, SM Dg 21, and SM Dg 22, however, 

indicating that the stable to slightly increasing withdrawals 

from the surrounding area (table 4) also may affect water 

levels in the aquifer at NASPR.

Ground-water levels in wells screened in the Piney PointNanjemoy aquifer at NASPR on April 28, 2006 were lower 

near the middle of the facility at well SM Dg 22 than near the 

Patuxent River at well SM Dg 21 or the Chesapeake Bay at 

well SM Dg 20 (fig. 6). A comparison of water levels in these 

wells with monthly withdrawal totals for each of the wells in 

southern Maryland indicates that water levels may have been 

affected by recent pumping from these and other nearby wells 

at NASPR.

Aquia Aquifer

Water withdrawals from the Aquia aquifer at NASPR 

have declined overall through time (table 3). Extrapolation 

of the historical data indicate that water withdrawals from 

the Aquia aquifer at NASPR are likely to have exceeded 

1.0 Mgal/d from at least 1946 through 1974, and likely were 

about 1.0 Mgal/d from 1975 through 1991. Withdrawals from 

the Aquia aquifer at NASPR typically were about 0.8 Mgal/d 

from 1992 through 1999, and about 0.7 Mgal/d from 2000 

through 2005. The Aquia aquifer typically has supplied more 

than 95 percent of the water used by NASPR.

Water withdrawals from the Aquia aquifer at WOLF 

also show an overall decrease from 1989 through 2005 

(table 3). Extrapolation of the historical data indicate that 

water withdrawals from the Aquia aquifer may have been less 

than 20,000 gal/d for much of the period prior to at least 1972. 

Withdrawals increased sometime between 1971 and 1989, and 

typically were about 75,000 gal/d from 1989 through 1991. 

Withdrawals from the Aquia aquifer at WOLF declined from 

about 56,000 gal/d in 1992 to about 40,000 gal/d in 1995 and 

were consistently about 28,000 gal/d from 1997 through 2001. 

Since 2001, withdrawals from the Aquia aquifer at WOLF 

have been less than 12,000 gal/d, partly because of a shift to 

pumping from a well drawing from the Upper Patapsco aquifer 

in 2002. Prior to 2002, all water withdrawals at WOLF were 

from the Aquia aquifer.

The potentiometric surface of the Aquia aquifer in 

southern Maryland from 1951–2003 shows a dynamic cone 

of depression in the Lexington Park-Solomons-NASPR area. 

This cone formed in an oblong shape around the Lexington 

Park area, expanding deeper and wider throughout the period 

of record (Weigle and Webb, 1970; Chapelle and others, 1981; 

Chapelle and Drummond, 1983; Mack and others, 1983, 1985, 

1987, 1989, 1990, 1991, 1992; Curtin and others, 1993a, 

1994a, 1995a, 1996a, 1997a, 1999b, 2001a, 2002a, 2003a, 

2005a). Otton (1955) prepared the first potentiometric-surface 

map of the Aquia aquifer in southern Maryland. This map 

shows a large cone of depression in the Lexington Park area in 

1951. A similar cone of depression was described by Weigle 

and Webb (1970), but water levels had declined approximately 

20 ft near Leonardtown as a result of increased municipal 

withdrawal. A potentiometric surface map created by Chapelle 

and Drummond (1983) delineates a cone of depression in 

NASPR-Lexington Park area with levels reported as low as 

-63 ft along the western boundary of NASPR and -83 ft just 

outside NASPR in Lexington Park in 1981. Curtin and others 

(1999a, 2001a, 2002a, 2003a, 2005a) showed an extensive 

cone of depression in the Aquia aquifer around well fields at 

Lexington Park and Solomons during periods of measurement 

in 1997, 1999, 2001, 2002, and 2003. During 2003, the 

potentiometric surface in the Aquia aquifer was more than 

-80 ft NAVD 88 in a 60-mi2 (square mile) area surrounding 

the deepest part of the cone of depression—measured values 

at NASPR were approximately -120 to -155 ft NAVD 88. 

The lowest measurement was -156 ft NAVD 88 in Lexington 

Park, Maryland (Curtin and others, 2005a). Curtin and others 

(2005b) showed that the potentiometric surface of the Aquia 

aquifer declined approximately 70 to 100 ft at NASPR from 

September 1982 to September 2003. Water levels in the 

aquifer declined more than 80 to 100 ft at Lexington Park, and 

about 60 ft near St. Marys City, just north of WOLF, during 

the same period.

Water-level records for wells measured by the USGS at 

NASPR and WOLF date as far back as the early 1940s for 

wells SM Df 1 and SM Df 10 screened in the Aquia aquifer, 

but water levels were not measured on a regular basis until 

the 1980s. Hydrographs of water levels for which 15 or more 

years of record exist show a declining trend in Aquia water 

levels of as much as 137 ft (fig. 7). The trend shows three 

phases at NASPR. The first phase occurred from about 1943 

until no later than 1984, when water levels in wells SM Df 1 

and SM Df 10 declined by about 43 to 50 ft, for a typical rate 

of about 1 ft/yr. The second phase occurred from about 1984 

until about 1999, when water levels in the aquifer declined by 

about an additional 50 to 80 ft, for a typical rate of about 

4 ft/yr. The third phase occurred after about 1999, during 

which water levels in the Aquia aquifer have remained fairly 

constant. For periods when four or measurements were available from a given well during a year, water levels in the Aquia 

aquifer at NASPR tended to be lower during the summer 

months than during the rest of the year, probably in response 

to seasonal trends in withdrawals.

Ground-Water Withdrawals and Water Levels 15
Figure 6. Altitude of water levels in the Piney Point-Nanjemoy aquifer on April 28, 2006, Naval Air Station Patuxent River, 

Maryland.

16 Hydrogeology of Selected Confined Aquifers, Naval Air Station Patuxent River, Maryland, 2000–06
Records for water levels in the Aquia aquifer at WOLF 

are not as extensive as those at NASPR. The longest waterlevel record for WOLF is for well SM Ff 64 (1998–2006). 

Water levels in this well have declined by about 14 ft overall 

during 8 years of measurement (fig. 7).

A comparison of trends in water levels in the Aquia aquifer at NASPR and WOLF with rates of withdrawal from the 

aquifer at NASPR and WOLF as well as the surrounding area 

indicates that water levels in the Aquia aquifer at NASPR and 

WOLF, although affected by pumping from the bases, also are 

affected by withdrawals from the aquifer in the surrounding 

area. The period of the most rapid decline in water levels in 

the Aquia aquifer at NASPR and WOLF (1984 through 1998 

or 1999) corresponds to a period of generally decreasing withdrawals from NASPR and WOLF (table 3), but substantially 

increasing withdrawals from the surrounding area (table 4). 

The more recent period of comparatively stable or low rates 

of decline in water levels in the Aquia aquifer at NASPR and 

WOLF (1999 or 2000 through April 2006) also corresponds 

to a period of generally decreasing withdrawals from NASPR 

and WOLF (table 3), but stable withdrawals from the surrounding area (table 4).

Ground-water levels in wells screened in the Aquia 

aquifer at NASPR on April 28, 2006 ranged from about 

-121 ft NAVD 88 at well SM Dg 19 on the eastern side of the 

facility to about -154 ft NAVD 88 at well SM Df 98 on the 

western side (fig. 8). These water levels are consistent with 

a composite cone of depression associated with pumping 

from the Aquia aquifer in wells located in the western part of 

NASPR and Lexington Park to the west. The potentiometric 

level of the Aquia aquifer in well SM Ff 64 at WOLF on 

April 28, 2006 was about -94 ft NAVD 88.

Upper Patapsco Aquifer

The Upper Patapsco aquifer is heavily used for water supply in Anne Arundel, Charles, and Prince Georges Counties, 

Maryland. In St. Marys County, Maryland, the Upper Patapsco 

was used for water supply by one well at Lexington Park near 

NASPR and one well at St. Inigoes near WOLF prior to 2002. 

Due to the declining water levels in the Aquia and, to a lesser 

extent, the Piney Point-Nanjemoy aquifers, however, NASPR 

and WOLF began using the Upper Patapsco aquifer as a watersupply source in 2003 and 2002, respectively.

Withdrawals from the Upper Patapsco aquifer at NASPR 

began in November 2003, when well SM DF 100 began to 

be pumped. Withdrawals from the Upper Patapsco aquifer 

at NASPR decreased from 37,300 gal/d in November and 

December 2003 to about 17,500 gal/d in 2005 (table 3).

Withdrawals from the Upper Patapsco aquifer at WOLF 

began in January 2002, when well SM Ff 65 began to be 

pumped. Withdrawals from the Upper Patapsco aquifer at 

WOLF have declined from more than 21,000 gal/d in 2002 

and 2003 to about 8,600 gal/d in 2005 (table 3).

Figure 7. Water levels for selected 

wells screened in the Aquia aquifer 

at Naval Air Station Patuxent River 

(NASPR) and Webster Outlying Field 

(WOLF), Maryland, 1943–2006.

Ground-Water Withdrawals and Water Levels 17
Figure 8. Altitude of water levels in the Aquia aquifer on April 28, 2006, Naval Air Station Patuxent River, Maryland.

18 Hydrogeology of Selected Confined Aquifers, Naval Air Station Patuxent River, Maryland, 2000–06
Maps of the potentiometric surface of the Upper Patapsco 

aquifer in southern Maryland indicate flow from the recharge 

area near the outcrop toward the south (Mack and others, 

1992; Curtin and others, 1993b, 1994b, 1995b, 1996b, 1997b, 

1999c, 2001b, 2002b, 2003b, 2005c; Achmad and Hansen, 

2001). Cones of depression were observed around pumping 

centers in the vicinity of LaPlata and Lexington Park-Kitts 

Point, Maryland, where the potentiometric level declined as 

much as 25 ft between 1990 and 2003 (Curtin and others, 

2005d).

The longest records of historical potentiometric level data 

for the Upper Patapsco aquifer in the vicinity of NASPR and 

WOLF are for well SM Ff 36 (beginning in 1978), located 

near WOLF at Kitts Point, Maryland and well SM Df 84 

(beginning in 1983), located near NASPR in Lexington Park, 

Maryland (fig. 9). The water-level altitude in well SM Ff 36 

declined continuously from -2.25 ft NAVD 88 in November 

1978 to -37.53 ft NAVD 88 in February 2006, an overall rate 

of decline of about 1.3 ft/yr. The water-level altitude in well 

SM Df 84 declined continuously from about -8 ft NAVD 88 

in January 1983 to -47.9 ft NAVD 88 in February 2006, an 

overall rate of decline of 1.7 ft/yr. The rate of decline has 

increased through time in both wells. From 1978 through 

1984, the rate of decline in well SM Ff 36 was about 0.9 ft/yr, 

from 1985 through 1996, the rate of decline was about 

1.3 ft/yr, and from 1997 to 2006, the rate of decline was about 

1.7 ft/yr. From 1983 through 1986, the rate of decline in well 

SM Df 84 was about 1.2 ft/yr, from 1987 through 1995, the 

rate of decline was about 1.7 ft/yr, and from 1996 to 2006, the 

rate of decline was about 2.0 ft/yr. Water-level declines in the 

Upper Patapsco aquifer at NASPR and WOLF are likely due 

to a combination of withdrawals from the aquifer in other parts 

of southern Maryland (beginning in at least 1978), nearby 

areas in St. Marys and Calvert Counties (beginning in 1995), 

and at NASPR and WOLF (beginning in 2003 and 2002, 

respectively). The timing and magnitude of the changes in the 

rate of water-level decline indicate that current (2006) water 

levels in the Upper Patapsco aquifer at NASPR and WOLF are 

declining primarily because of pumping from the aquifer in 

other parts of southern Maryland, followed by pumping from 

nearby areas, with pumping at NASPR and WOLF having the 

least impact. Pumping from both facilities is likely to affect 

drawdown in the future.

Water levels in well SM Df 100 at NASPR have declined 

from -37.65 ft in September 2000, shortly after the well was 

drilled, to -47.83 ft NAVD 88 on April 28, 2006 (figs. 9 and 

10). This corresponds to a rate of decline of about 1.8 ft/yr. 

Water levels in well SM Ff 65 at WOLF have declined from 

-29.87 ft NAVD 88 in September 2001 to -37.03 ft NAVD 

88 on April 28, 2006 (figs. 9 and 10). This corresponds to a 

rate of decline of about 1.5 ft/yr. These rates of decline are 

consistent with the recent values for Lexington Park and Kitts 

Point, and indicate that the rate of decline is slightly higher 

near NASPR than near WOLF, presumably because withdrawals near NASPR are greater than those near WOLF.

Figure 9. Water levels for 

selected wells screened in the 

Upper Patapsco aquifer at Naval 

Air Station Patuxent River (NASPR) 

and Webster Outlying Field (WOLF), 

Maryland, 1978–2006.

Ground-Water Withdrawals and Water Levels 19
Figure 10. Altitude of water levels in the Upper Patapsco aquifer on April 28, 2006, Naval Air Station Patuxent River and 

Webster Outlying Field, Maryland.

20 Hydrogeology of Selected Confined Aquifers, Naval Air Station Patuxent River, Maryland, 2000–06
Water levels in the Upper Patapsco aquifer are greater 

than those in the overlying Aquia aquifer, indicating the 

potential for flow from the Upper Patapsco aquifer up to the 

Aquia aquifer in this area (see figures 8 and 10). It is possible, 

therefore, that the Aquia aquifer receives some recharge from 

both the Middle and Lower confining units, and that the Upper 

Patapsco aquifer loses water both to pumping withdrawals and 

flow to the Middle confining unit. Water levels indicate that 

flow in the Upper Patapsco aquifer in the vicinity of NASPR 

and WOLF is from south to north, toward the centers of 

pumping in southern Maryland.

Transmissivity of the Upper Patapsco 

Aquifer

Long-term, constant-discharge aquifer tests were performed in two wells (SM Df 100 and SM Ff 65) screened in 

the Upper Patapsco aquifer at NASPR and WOLF, respectively. These tests were performed to determine the transmissivity of the aquifer in both areas.

Well SM Df 100 is located in the northwestern part of 

NASPR (fig. 2). The altitude of land surface at SM Df 100 

is about 21 ft NAVD 88 (U.S. Geological Survey, 1974). 

The well has a diameter of 10 in. (inches) from land surface 

to a depth of 705 ft, and 8 in. from 705 to 910 ft below land 

surface (including the screened intervals) (table 1). SM Df 100 

is screened in the Upper Patapsco aquifer over the following 

intervals (ft below land surface): 706 to 716, 744 to 754, 835 

to 860, 882 to 892, and 900 to 905, for a total of 60 ft of open 

interval over a total length of 199 ft.

Well SM Df 100 was pumped at 400 gal/min (gallons per 

minute) for 96 hours from August 8, 2000 through August 12, 

2000. Water levels were measured in well SM Df 100 and in 

five observation wells (all of which are screened in the Aquia 

aquifer) for the period of pumping (pumping phase of test), 

and for 96 hours after pumping terminated (recovery phase 

of test). The Aquia wells were monitored to see if there was 

any interaction between the Upper Patapsco aquifer and the 

Aquia aquifer. Because other production wells in the Aquia 

were pumped during the test, drawdown due to pumping from 

well SM Df 100 could not be verified in any of the observation 

wells screened in the Aquia aquifer. Therefore, the aquifer test 

data were analyzed using only the data from the pumped well 

SM Df 100.

 Drawdown data from well SM Df 100 were evaluated 

by use of the straight-line method of Cooper and Jacob (1946) 

(fig. 11). This technique is used to evaluate the drawdown 

and recovery data from aquifer testing in a confined aquifer 

and assumes the aquifer is isotropic, homogeneous, and 

areally extensive. The technique also assumes that the 

pumping rate and well loss are constant. Analysis of the data 

from the pumping and recovery phases of the test indicated 

transmissivities of about 3,900 and 4,600 ft2/d (feet squared 

per day), respectively.

Figure 11. Analysis of timedrawdown data for well SM Df 100 

at Naval Air Station Patuxent River, 

Maryland, August 8–12, 2000.

Transmissivity of the Upper Patapsco Aquifer 21
Well SM Ff 65 is located in the south-central part of 

WOLF (fig. 2). The altitude of land surface at SM Ff 65 is 

about 10 ft NAVD 88 (U.S. Geological Survey, 1974). The 

well has a diameter of 10 in. from land surface to a depth 

of 635 ft, and 8 in. from 635 to 884 ft below land surface 

(including the screened intervals). SM Ff 65 is screened in the 

Upper Patapsco aquifer at the following intervals (ft below 

land surface): 635 to 640, 648 to 658, 689 to 694, 782 to 792, 

846 to 856, and 864 to 874, for a total open interval of 50 ft, 

over a length of 239 ft.

Well SM Ff 65 was pumped at a rate of 375 gal/min 

for 24 hours on August 6 and 7, 2001. Water levels were 

monitored in pumped well SM Ff 65 and observation wells 

SM Ff 36 and SM Ff 37 for the period of pumping and for 

24 hours after pumping was terminated. Well SM Ff 36 is 

screened in the Upper Patapsco aquifer, approximately 1.5 mi 

south of well SM Ff 65 (fig. 3). Well SM Ff 37 is screened 

in the Upper Patapsco aquifer near SM Ff 65 (fig. 2). No 

drawdown was measured in either observation well. Therefore, 

only the data from pumped well SM Ff 65 were analyzed.

Drawdown data from well SM Ff 65 also were evaluated 

by use of the technique of Cooper and Jacob (1946) (fig. 12). 

Analysis of the data from the pumping and recovery phases 

of the test indicated transmissivities of about 2,100 and 

2,800 ft2/d, respectively.

Ground-Water Quality in the 

Upper Patapsco Aquifer

Water samples were collected from well SM Df 100 on 

August 11, 2000, and from well SM Ff 65 on August 7, 2001, 

near the end of the pumping part of their respective aquifer 

tests. Water temperature, pH, specific conductance, and acidneutralizing capacity were measured at the site. Water samples 

also were sent to the U.S. Geological Survey National Water 

Quality Laboratory in Denver, Colorado, for analysis of major 

ions, trace metals, and some radionuclides. A list of all constituents and their corresponding concentrations in the sample 

is provided in table 5.

The principal cation and anion in both samples are 

sodium and bicarbonate, respectively. The trace metal 

concentrations were all below the detection limit except for 

aluminum, zinc, lithium, molybdenum, strontium, and copper. 

The concentrations of all constituents were below the national 

primary drinking water regulation maximum contaminant 

level as regulated by the U.S. Environmental Protection 

Agency (U.S. Environmental Protection Agency, 1999). 

Concentrations of all constituents except silica, iron, and 

radium-228 were greater in well SM Ff 65 than in well 

DM Df 100. Further characterization of the water quality of 

the Upper Patapsco aquifer based on these samples is limited 

because samples were only collected from two wells, only 

collected once at each well, and were sampled in different 

years.

Figure 12. Analysis of timedrawdown data for well SM Ff 65 at 

Webster Outlying Field, Maryland, 

August 6–7, 2001.

22 Hydrogeology of Selected Confined Aquifers, Naval Air Station Patuxent River, Maryland, 2000–06
Table 5. Concentrations of constituents in ground water from wells SM Df 100 and SM Ff 65 at 

Naval Air Station Patuxent River and Webster Outlying Field, Maryland, 2000–01.

[μS/cm, microsiemens per centimeter; mg/L, milligrams per liter; na, not analyzed; μg/L, micrograms per liter; pCi/L, 

picocuries per liter; <, less than; CaCO3, calcium carbonate; CO3

2-, carbonate; HCO3-

, bicarbonate]

Constituent Well SM Df 100 Well SM Ff 65 Units

Specific conductance, field 238 508 μS/cm

Specific conductance, lab 260 538 μS/cm

pH field 8.4 8.5 standard units

Calcium (dissolved) .39 0.8 mg/L 

Magnesium (dissolved) .2 0.388 mg/L 

Sodium (dissolved) 56.3 127 mg/L 

Potassium (dissolved) 2.3 4.11 mg/L 

Acid-neutralizing capacity, field titration 127 285 mg/L as CaCO3

Acid-neutralizing capacity, laboratory titration 177 277 mg/L as CaCO3

Carbonate, field na 7.3 mg/L as CO3

2-

Bicarbonate 155 332 mg/L as HCO3

-

Sulfate (dissolved) 4.6 12.5 mg/L

Chloride (dissolved) 1.7 2.1 mg/L

Fluoride (dissolved) .4 0.8 mg/L 

Silica (dissolved) 12.6 12.1 mg/L

Barium (dissolved) 6.7 12.4 μg/L

Boron (total) na 318 μg/L

Bromide (dissolved) 0.02 0.04 mg/L 

Iron (dissolved) 50 30 μg/L

Manganese (dissolved) 9 11.3 μg/L

Nitrate + nitrite (dissolved) <0.1 na mg/L

Radium-228, (dissolved, pCi/L as Ra-228) <1.00 .725 pCi/L

Radium-228, 2 sigma, (pCi/L) 0.38 0.33 pCi/L

Uranium (natural, dissolved) <.02 < 0.02 μg/L

Cyanide <0.01 na mg/L

Mercury <0.01 na μg/L

Aluminum na 4 μg/L

Beryllium <2 <0.6 μg/L 

Nickel <50 <0.06 μg/L

Arsenic <1 <0.2 μg/L

Chromium <1 <0.8 μg/L

Thallium <1.0 <0.4 μg/L

Cadmium <1.0 <0.04 μg/L

Antimony <1.0 <0.05 μg/L

Selenium <1.0 <0.3 μg/L

Lead <1.0 <0.08 μg/L

Zinc <20 3 μg/L

Lithium na 4.8 μg/L

Molybdenum na 2.4 μg/L

Cobalt na <0.2 μg/L

Silver na <1.0 μg/L

Strontium na 16.5 μg/L

Vanadium na <0.2 μg/L

Copper na 0.3 μg/L

Ground-Water Quality in the Upper Patapsco Aquifer 23
Summary and Conclusions

Ground-water withdrawals have resulted in deep cones 

of depression in aquifers used for water supply in parts of 

southern Maryland. Recent and projected population growth 

in southern Maryland is likely to exacerbate decreases in the 

potentiometric surfaces of these aquifers. As a result, the 

U.S. Geological Survey (USGS), in cooperation with Naval 

Air Station Patuxent River (NASPR), has conducted an 

ongoing investigation of the hydrogeology and water quality 

of the Piney Point-Nanjemoy and Aquia aquifers in the 

vicinity of NASPR and Webster Outlying Field (WOLF). 

Lithologic, borehole geophysical, water-level, and water-use 

data were compiled and interpreted to revise understanding of 

the hydrogeologic framework of the Piney Point-Nanjemoy, 

Aquia, and Upper Patapsco aquifers in southern Maryland, 

with emphasis on the Naval Air Station Patuxent River and 

WOLF. Understanding of the hydrogeologic framework for 

the Upper Patapsco aquifer also has been revised based on the 

results of aquifer testing and water-quality sampling of two 

wells.

The Piney Point-Nanjemoy aquifer is 50 to 70 feet 

thick, with a top altitude of -213 to -260 feet from the North 

American Vertical Datum of 1988 (NAVD 88) and a horizontal 

hydraulic conductivity of 2 feet per day at NASPR and WOLF. 

The Aquia aquifer is 50 to 145 feet thick, with a top altitude 

of -450 feet NAVD 88 and a hydraulic conductivity of 6 to 

10 feet per day at NASPR and WOLF. The Upper Patapsco 

aquifer at the NASPR and WOLF consists of layers of sand 

interbedded with layers of clay that total over 200 feet in 

thickness. The altitude of the top of the Upper Patapsco 

aquifer is approximately -625 to -660 feet NAVD 88 at 

NASPR and WOLF.

The Piney Point-Nanjemoy, Aquia, and Upper Patapsco 

aquifers are sources of water supply for the NASPR and 

WOLF, as well as for nearby municipalities and industries 

in southern Maryland. Ground-water withdrawals from the 

Piney Point-Nanjemoy and Aquia aquifers at the NASPR 

and WOLF (Aquia aquifer only) began in 1942. Groundwater withdrawals from the Upper Patapsco aquifer at WOLF 

and NASPR began in 2002 and 2003, respectively. In 2005, 

about 710 gallons per day were pumped from the Piney 

Point-Nanjemoy aquifer, about 657,000 gallons per day were 

pumped from the Aquia aquifer, and about 17,500 gallons per 

day were pumped from the Upper Patapsco aquifer at NASPR. 

About 11,500 gallons per day were withdrawn from the Aquia 

aquifer and about 8,600 gallons per day were withdrawn from 

the Upper Patapsco aquifer at WOLF in 2005.

Water levels in the Piney Point-Nanjemoy aquifer at 

NASPR have not changed substantially during the past 

52 years, and are approximately -20 feet NAVD 88. Water 

levels may have shown an overall decrease of about 2.5 ft 

from 1998 through April 2006. Water levels in the Piney 

Point-Nanjemoy aquifer at NASPR appear to be affected 

by pumping withdrawals at the facility and perhaps in the 

surrounding area.

Water levels in the Aquia aquifer decreased as much as 

136 feet from 1943 through April 2006 at the NASPR and 

WOLF. The rate of decrease was greatest from about 1984 

through 1999, when water levels declined about 4 feet per 

year. Water levels in the Aquia aquifer have remained stable 

overall since about 2000. In April 2006, water levels in the 

Aquia aquifer ranged from about -154 ft NAVD 88 in the 

western part of NASPR to about -121 ft in the eastern part. 

Water levels in the Aquia aquifer in April 2006 were about 

-92 ft NAVD 88 at WOLF. Water levels in the Aquia aquifer 

at the NASPR and WOLF appear to be affected by pumping at 

these facilities and in the surrounding area.

Water levels in the Upper Patapsco aquifer in the vicinity 

of NASPR and WOLF declined from about 1.3 to 1.7 feet per 

year overall between 1978 and April 2006. The rate of decline 

has increased through time from about 0.9 to 1.6 feet per year 

during 1978 through 1984, to about 1.7 to 2.0 feet per year 

from 1997 to April 2006. The rate of decline was greater in the 

vicinity of NASPR and WOLF. Water levels in the Upper Patapsco aquifer at NASPR and WOLF appear to be affected primarily by pumping throughout southern Maryland, although 

pumping at the facilities is likely to affect future drawdown.

Aquifer testing at two wells screened in the Upper 

Patapsco aquifer indicates the transmissivity of the aquifer 

is about 2,100 to 4,600 feet squared per day at NASPR and 

WOLF. Aquifer transmissivity appears to be lower at WOLF 

than at NASPR. Water samples collected from these wells near 

the end of the pumping part of their respective aquifer tests 

in 2000 and 2001 indicate the water in the Upper Patapasco 

aquifer at NASPR and WOLF is a sodium-bicarbonate type.

Acknowledgments

The authors thank the personnel at NASPR who assisted 

the project, especially those in the Public Works Department, 

the Environmental Support Group, and the Public Affairs 

Office. In addition, the authors thank the many reviewers of 

this report for their helpful comments, and the U.S. Geological 

Survey employees who assisted in field data collection.

References Cited

Achmad, G., and Hansen, H.J., 1997, Hydrogeology, model 

simulation, and water-supply potential of the Aquia and 

Piney Point-Nanjemoy aquifers in Calvert and St. Marys 

Counties, Maryland: Maryland Geological Survey Report 

of Investigations No. 64, 197 p.

24  Hydrogeology of Selected Confined Aquifers, Naval Air Station Patuxent River, Maryland, 2000–06
Achmad, G., and Hansen, H.J., 2001, Ground-water levels and 

pumpage trends in the major coastal plain aquifers of southern Maryland between 1970 and 1996: Maryland Geological Survey Open-File Report No. 00-02-12, 150 p.

Bennett, R.R., 1944, Ground-water resources at the Naval 

establishments in the Solomons-Patuxent River area, Maryland: U.S. Geological Survey Open-File Report, 35 p.

Chapelle, F.H., and Drummond, D.D., 1983, Hydrogeology, 

digital simulation, and geochemistry of the Aquia and Piney 

Point-Nanjemoy Aquifer System in Southern Maryland: 

Maryland Geological Survey Report of Investigations 

No. 38, 100 p.

Chapelle, F.H., Drummond, D.D., and Curley, T., 1981, Map 

showing the potentiometric surface of the Aquia aquifer, 

May 19–23, 1980: U.S. Geological Survey Open-File 

Report 81–416, 1 p.

Cooper, H.H., and Jacob, C.E., 1946, A generalized graphical 

method for evaluating formation constants and summarizing 

well-field history: American Geophysical Union Transactions, v. 27, no. 4, p. 526–534.

Curtin, S.E., Andreasen, D.C., and Mack, F.K., 1993a, Potentiometric surface of the Aquia aquifer in Southern Maryland, September 1991: U.S. Geological Survey Open-File 

Report 93–652, 1 p.

Curtin, S.E., Andreasen, D.C., and Mack, F.K., 1993b, Potentiometric surface of the Upper Patpasco aquifer in Southern 

Maryland, September 1991: U.S. Geological Survey OpenFile Report 93–654, 1 p.

Curtin, S.E., Mack, F.K., and Andreasen, D.C., 1994a, Potentiometric surface of the Aquia aquifer in Southern Maryland, September 1993: U.S. Geological Survey Open-File 

Report 94–390, 1 p.

Curtin, S.E., Mack, F.K., and Andreasen, D.C., 1994b, Potentiometric surface of the Upper Patpasco aquifer in Southern 

Maryland, September 1993: U.S. Geological Survey OpenFile Report 94–392, 1 p.

Curtin, S.E., Mack, F.K., and Andreasen, D.C., 1995a, Potentiometric surface of the Aquia aquifer in Southern Maryland, September 1994: U.S. Geological Survey Open-File 

Report 95–743, 1 p.

Curtin, S.E., Mack, F.K., and Andreasen, D.C., 1995b, Potentiometric surface of the Upper Patpasco aquifer in Southern 

Maryland, September 1994: U.S. Geological Survey OpenFile Report 95–745, 1 p.

Curtin, S.E., Andreasen, D.C., and Mack, F.K., 1996a, Potentiometric surface of the Aquia aquifer in Southern Maryland, September 1995: U.S. Geological Survey Open-File 

Report 96–620, 1 p.

Curtin, S.E., Mack, F.K., and Andreasen, D.C., 1996b, Potentiometric surface of the Upper Patpasco aquifer in Southern 

Maryland, September 1995: U.S. Geological Survey OpenFile Report 96–622, 1 p.

Curtin, S.E., Andreasen, D.C., and Mack, F.K., 1997a, Potentiometric surface of the Aquia aquifer in Southern Maryland, September–October 1996: U.S. Geological Survey 

Open-File Report 97–788, 1 p.

Curtin, S.E., Mack, F.K., and Andreasen, D.C., 1997b, Potentiometric surface of the Upper Patpasco aquifer in Southern 

Maryland, September–October 1996: U.S. Geological 

Survey Open-File Report 97–790, 1 p.

Curtin, S.E., Andreasen, D.C., and Mack, F.K., 1999a, The 

difference between the potentiometric surfaces of the Aquia 

aquifer, September 1982 and September 1997 in Southern Maryland: U.S. Geological Survey Open-File Report 

99–81, 1 p.

Curtin, S.E., Andreasen, D.C., and Mack, F.K., 1999b, Potentiometric surface of the Aquia aquifer in Southern Maryland, September 1997: U.S. Geological Survey Open-File 

Report 99–82, 1 p.

Curtin, S.E., Mack, F.K., and Andreasen, D.C., 1999c, Potentiometric surface of the Upper Patpasco aquifer in Southern 

Maryland, September 1997: U.S. Geological Survey OpenFile Report 99–85, 1 p.

Curtin, S.E., Andreasen, D.C., and Wheeler, J.C., 2001a, 

Potentiometric surface of the Aquia aquifer in Southern 

Maryland, September 1999: U.S. Geological Survey OpenFile Report 01–204, 1 p.

Curtin, S.E., Andreasen, D.C., and Wheeler, J.C., 2001b, 

Potentiometric surface of the Upper Patapsco aquifer in 

Southern Maryland, September 1999: U.S. Geological 

Survey Open-File Report 01–208, 1 p.

Curtin, S.E., Andreasen, D.C., and Wheeler, J.C., 2002a, 

Potentiometric surface of the Aquia aquifer in Southern 

Maryland, September 2001: U.S. Geological Survey OpenFile Report 02–442, 1 p.

Curtin, S.E., Andreasen, D.C., and Wheeler, J.C., 2002b, 

Potentiometric surface of the Upper Patapsco aquifer in 

Southern Maryland, September 2001: U.S. Geological 

Survey Open-File Report 02–446, 1 p.

Curtin, S.E., Andreasen, D.C., and Wheeler, J.C., 2003a, 

Potentiometric surface of the Aquia aquifer in Southern 

Maryland, September 2002: U.S. Geological Survey OpenFile Report 03–255, 1 p.

Curtin, S.E., Andreasen, D.C., and Wheeler, J.C., 2003b, 

Potentiometric surface of the Upper Patapsco aquifer in 

Southern Maryland, September 2002: U.S. Geological 

Survey Open-File Report 03–257, 1 p.

References Cited 25
Curtin, S.E., Andreasen, D.C., and Wheeler, J.C., 2005a, 

Potentiometric surface of the Aquia aquifer in Southern 

Maryland, September 2003: U.S. Geological Survey OpenFile Report 2005–1004, 1 p.

Curtin, S.E., Andreasen, D.C., and Wheeler, J.C., 2005b, The 

difference between the potentiometric surfaces of the Aquia 

aquifer, September 1982 and September 2003 in Southern Maryland: U.S. Geological Survey Open-File Report 

2005–1005, 1 p.

Curtin, S.E., Andreasen, D.C., and Wheeler, J.C., 2005c, 

Potentiometric surface of the Upper Patapsco aquifer in 

Southern Maryland, September 2003: U.S. Geological 

Survey Open-File Report 2005–1008, 1 p.

Curtin, S.E., Andreasen, D.C., and Wheeler, J.C., 2005d, The 

difference between the potentiometric surfaces of the Upper 

Patapsco aquifer, September 1990 and September 2003 in 

Southern Maryland: U.S. Geological Survey Open-File 

Report 2005–1009, 1 p.

Darton, N.H., 1896, Artesian well prospects in the Atlantic 

Coastal Plain region: U.S. Geological Survey Bulletin 138, 

232 p.

Drummond, D.D., 2005, Water-supply potential of the Coastal 

Plain aquifers in Calvert, Charles, and St. Mary’s Counties, 

Maryland, with emphasis on the Upper Patapsco and Lower 

Patapsco aquifers: Maryland Geological Survey Administrative Report, June 2005, 70 p.

Klohe, C.A., and Feehley, C.E., 2001, Hydrogeology and 

ground-water quality of the Piney Point-Nanjemoy and 

Aquia aquifers, Naval Air Station Patuxent River and 

Webster Outlying Field, St. Marys County, Maryland: 

U.S. Geological Survey Water-Resources Investigations 

Report 01–4029, 51 p.

Mack, F.K., Andreasen, D.C., Curtin, S.E., and Wheeler, 

J.C., 1987, Potentiometric surface of the Aquia aquifer in 

Southern Maryland during the fall of 1986: U.S. Geological 

Survey Water-Resources Investigations Report 87–4214, 

1 p.

Mack, F.K., Andreasen, D.C., Curtin, S.E., and Wheeler, 

J.C., 1989, Potentiometric surface of the Aquia aquifer in 

Southern Maryland during the fall of 1987: U.S. Geological 

Survey Water-Resources Investigations Report 89–4012, 

1 p.

Mack, F.K., Andreasen, D.C., Curtin, S.E., and Wheeler, J.C., 

1990, Potentiometric surface of the Aquia aquifer in Southern Maryland during September 1998: U.S. Geological Survey Water-Resources Investigations Report 90–4037, 1 p.

Mack, F.K., Curtin, S.E., Andreasen, D.C., and Wheeler, J.C., 

1991, Potentiometric surface of the Aquia aquifer in Southern Maryland, September 1989: U.S. Geological Survey 

Water-Resources Investigations Report 91–4094, 1 p.

Mack, F.K., Curtin, S.E., Andreasen, D.C., and Wheeler, J.C., 

1992, Potentiometric surface of the Aquia aquifer in Southern Maryland, September 1990: U.S. Geological Survey 

Open-File Report 92–459, 1 p.

Mack, F.K., Wheeler, J.C., and Curtin, S.E., 1983, Preliminary 

map showing the potentiometric surface of the Aquia aquifer in Southern Maryland, September 1982: U.S. Geological Survey Open-File Report 83–929, 1 p.

Mack, F.K., Wheeler, J.C., Curtin, S.E., and Andreasen, D.C., 

1985, Preliminary map showing the potentiometric surface 

of the Aquia aquifer in Southern Maryland, September 

1984: U.S. Geological Survey Water-Resources Investigations Report 85–4338, 1 p.

Mack, F.K., Wheeler, J.C., Curtin, S.E., Andreasen, D.C., and 

Wheeler, J.C., 1992, Potentiometric surface of the Upper 

Patapsco aquifer in Southern Maryland, September 1990: 

U.S. Geological Survey Open-File Report 92–461, 1 p.

Naval Air Station Patuxent River, Naval Air Station History: 

accessed December 4, 2000, at URL http://nas.nawcad.

navy.mil

Otton, E.G., 1955, Ground-water resources of the Southern 

Maryland Coastal Plain: Maryland Department of Geology, 

Mines, and Water Resources Bulletin 15, 347 p.

U.S. Environmental Protection Agency, 1999, Code of Federal 

Regulations 40, Part 141—National Primary Drinking 

Water Regulations: Washington, D.C., Office of the Federal 

Register, [variously paged.]

U.S. Geological Survey, 1974, Solomons Island Quadrangle, 

Maryland: U.S. Geological Survey Topographic Quadrangle Map 5760 IV SW, scale 1:24,000, 1 sheet.

Vroblesky, D.A., and Fleck, W.B., 1991, Hydrogeologic 

framework of the Coastal Plain of Maryland, Delaware, and 

the District of Columbia: U.S. Geological Survey Professional Paper 1404–E, 45 p.

Weigle, J.M., and Webb, W.E., 1970, Southern Maryland 

records of selected wells, water levels and chemical analyses of water: Maryland Geological Survey Basic Data 

Report No. 4, 48 p.

Williams, J.F., III, 1979, Simulated changes in water level in 

the Piney Point Aquifer in Maryland: Maryland Geological 

Survey Report of Investigations No. 31, 49 p.

26 Hydrogeology of Selected Confined Aquifers, Naval Air Station Patuxent River, Maryland, 2000–06
Prepared by Publishing Service Centers 3 and 1.

Edited by Valerie M. Gaine.

Graphics by Timothy W. Auer.

Layout by Ann Marie Squillacci.

For additional information, contact:

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U.S. Geological Survey

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or visit our Web site at:

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