Toxic Substances Hydrology Program in cooperation with the 

Army Environmental Center

Ground-Water Levels near the Top of the 

Water-Table Mound, Western Cape Cod, 

Massachusetts, 2002–04

By Andrew J. Massey, Carl S. Carlson, and Denis R. LeBlanc

Scientific Investigations Report 2006–5054

U.S. Department of the Interior

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

Gail A. Norton, Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

U.S. Geological Survey, Reston, Virginia: 2006

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Suggested citation:

Massey, A.J., Carlson, C.S., and LeBlanc, D.R., 2006, Ground-water levels near the top of the water-table mound, western 

Cape Cod, Massachusetts, 2002–04: U.S. Geological Survey Scientific Investigations Report 2006-5054, 13 p.
iii

CONTENTS

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

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

Water-Level and Precipitation Observations...................................................................................3

Water-Level-Monitoring Equipment.........................................................................................3

Precipitation Measurements.....................................................................................................3

Estimation of Recharge ..............................................................................................................3

Ground-Water Levels at Camp Edwards ..........................................................................................6

Response of Ground-Water Levels to Long-Term Precipitation Trends ............................6

Changes in Ground-Water Levels with Individual Precipitation Events ............................7

Summary ..............................................................................................................................................10

Acknowledgments .............................................................................................................................12 

References ..........................................................................................................................................12

FIGURES

1. Map showing the Southeast Ranges of Camp Edwards military-training area, the 

simulated water table, monitoring wells, and NOAA weather stations KFMH 

on Otis Air National Guard Base, western Cape Cod, and at East Wareham, 

Massachusetts........................................................................................................................2

2. Graphs showing A, manual measurements and hydrographs of continuous water levels 

recorded in three wells between the Southeast Ranges of Camp Edwards and Snake 

Pond, western Cape Cod; B, estimated daily recharge; and C, daily precipitation 

recorded at NOAA weather station KFMH on Otis Air National Guard Base, western 

Cape Cod, from January 9, 2002, to December 31, 2004...................................................5 

3-5. Hydrographs showing:

3. A, Monthly water levels measured manually in USGS well MA-SDW 253, 1962–2004, 

and continuously in well MA-SDW 525-0109, 2002–2004; and B, water levels 

measured manually in wells MA-SDW 525-0109, MA-SDW 526-0040, and MASDW 527-0055 near the Southeast Ranges of Camp Edwards at the top of the 

water-table mound, and in well MA-SDW 253 east of Camp Edwards, western 

Cape Cod, 2002–04.........................................................................................................9

4. Continuous water levels recorded in three wells between the Southeast Ranges 

of Camp Edwards and Snake Pond, western Cape Cod, with bar graphs of 

precipitation and estimated recharge, May through July 2002 ...........................10 

5. Continuous water levels recorded in three wells between the Southeast 

Ranges of Camp Edwards and Snake Pond, western Cape Cod, with bar 

graphs of precipitation and estimated recharge, November 2002 through 

January 2003.................................................................................................................11 
iv

TABLES 

1. Monitoring-well characteristics and water-level-recorder information, Camp Edwards, 

western Cape Cod, Massachusetts .....................................................................................4

2. Characteristics of automated water-level-recording and manual-measurement 

devices......................................................................................................................................4

3. Monthly and annual precipitation at National Oceanic and Atmospheric Administration 

Weather Station KFMH at Otis Air National Guard Base, western Cape Cod, 

1998–2004..................................................................................................................................8

4. Monthly and annual precipitation for the period 1971 to 2000 at three National Oceanic 

and Atmospheric Administration weather stations near Otis Air National Guard 

Base, western Cape Cod........................................................................................................8 

5. Estimated recharge determined from two daily soil-water balance approaches—Jensen 

and Haise (1963) and Thornthwaite (1948)—and annual precipitation at Otis Air 

National Guard Base, western Cape Cod, 2002–04 .........................................................11
CONVERSION FACTORS AND DATUMS

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Pressure

pound per square inch (lb/in2) 6.895 kilopascal (kPa) 

Hydraulic conductivity

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

Temperature in degrees Fahrenheit (oF) may be converted to degrees 

Celsius (oC) as follows: oC=(oF-32)/1.8 

Vertical coordinate information is referenced to the National Geodetic Vertical 

Datum of 1929 (NGVD 29).

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

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

In January 2002 the U.S. Geological Survey began continuous water-level monitoring in three wells in the vicinity of 

the Southeast Ranges of Camp Edwards, near the Impact Area 

of the Massachusetts Military Reservation on Cape Cod. The 

purpose of this effort was to examine how water levels at sites 

with different unsaturated-zone thicknesses near the top of the 

water-table mound beneath western Cape Cod are affected by 

temporally variable recharge from precipitation, which is the 

sole source of water to the sand and gravel aquifer. The depths 

to water at the well sites are about 18, 30, and 101 feet below 

land surface.

This report presents the first 3 years of water-level 

records and an estimate of aquifer recharge calculated from 

climatological measurements by the Jensen and Haise method 

and the Thornthwaite method. The water levels in the three 

wells varied temporally by about 4.5 feet during the study 

period. A comparison of the water levels with those measured 

in a nearby monitoring well with about 42 years of monthly 

measurements indicates that the 3-year monitoring period 

included the lowest water levels on western Cape Cod since 

the drought of the 1960’s. The response of water levels to 

recharge was related to the depth to water. Water levels in 

the two wells with shallow depths to water responded quickly 

(within hours or days) to recharge, whereas the water-level 

response in the well with the greatest depth to water often 

lagged the recharge event by a month or more. The variations 

in the water levels among the wells changed as the location 

of the top of the water-table mound moved with the changing 

water-table altitude. 

Introduction

The aquifer system underlying Cape Cod is composed of 

unconsolidated sandy sediments deposited during the retreat 

of the continental ice sheet at the end of the Pleistocene Epoch 

15,000–16,000 years ago (Oldale and Barlow, 1986). The 

source of all freshwater stored within these glacial sediments 

is precipitation that falls directly on the Cape (Strahler, 1972; 

LeBlanc and others, 1986). The water in the unconfined aquifer forms six mounds, or lenses, and ground water generally 

flows radially outward from the top of the mounds toward the 

coast. Surface-water bodies and pumping from wells alter this 

pattern in many locations (Walter and Masterson, 2003). The 

Sagamore Lens, the part of the aquifer that underlies westernmost Cape Cod, forms a water-table mound that rises to a 

maximum altitude of about 70 ft beneath the Southeast Ranges 

of Camp Edwards on the Massachusetts Military Reservation 

(MMR) (Walter and Whealan, 2005) (fig. 1). 

The U.S. Geological Survey (USGS) began systematic 

measurements of ground-water levels on Cape Cod in 1950 

in Truro, MA. During the 1960s, in response to concerns 

raised by a drought in the region, several more observation 

wells were installed to monitor water levels in the aquifer. In 

1972, the Association to Preserve Cape Cod placed staff gages 

in kettle ponds across the Cape to monitor pond levels. The 

USGS mapped the Cape Cod water table in detail in 1975–77 

as part of an assessment of the ground-water resources 

(LeBlanc and others, 1986). In 1982, the U.S. Environmental 

Protection Agency designated Cape Cod as a “sole source 

aquifer” in recognition of the fact that precipitation falling 

directly on the Cape is the only source of freshwater. The 

designation highlighted the importance of protecting areas for 

recharge (Ryan, 1980).

During the late 1990s, ground-water-flow models were 

developed to delineate the contributing areas for proposed and 

existing public water-supply wells on western Cape Cod 

(Masterson and others, 1998). Walter and Masterson (2003) 

used a ground-water-flow model of the western part of the 

Sagamore Lens to demonstrate that the location of the top of 

the mound, and therefore flow direction, changed as water 

levels changed seasonally and from year to year.

In January 2002, the USGS, in cooperation with the 

Army Environmental Center (AEC) at the MMR, began continuous monitoring of ground-water levels in three wells near 

the top of the water-table mound to support ongoing studies by 

the AEC Impact Area Groundwater Study Program 

(IAGWSP). These studies relate military activities at the 

MMR with the chemical signatures of explosives and other 

ordnance-related contaminants that have been detected in 

ground water near the MMR. The monitoring period included 

a drought that had begun in 2001 (Air Force Center for Environmental Excellence, 2003). During the drought, the water 

table declined to levels not observed since the 1960s. The 

relation between the timing and magnitude of precipitation, 

estimated recharge, and changes in water levels at different 

locations near the top of the water-table mound beneath 

western Cape Cod were investigated on the basis of the measurements.

This report presents water-level data collected with 

digital recorders at three observation wells near the top of 

the mound during the 3-year period January 2002–December 

2004, and illustrates differences in the responses of the water 

levels to recharge for a range of unsaturated-zone thicknesses. 

Water levels observed in the wells during the period were also 

compared to the water levels at a nearby well with more than 

40 years of record. 

Ground-Water Levels near the Top of the Water-Table 

Mound, Western Cape Cod, Massachusetts, 2002-04

by Andrew J. Massey, Carl S. Carlson, and Denis R. LeBlanc
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MA-SDW 527-0055

MA-SDW 525-0109

MA-SDW 526-0040

SOUTHEAST 

RANGES

MA-SDW 253

KFMH

KFMH

70 32' 70 30' 70 28'

41 40'

41 42'

0

0 6,000 12,000

1,200 2,400 3,600 METERS

3,000 9,000 FEET

MA-SDW 527-0055

Base from Massachusetts Office of Geographic and 

Environmental Information 1:5,000 color digital ortho images

Peters 

Pond

Wakeby Pond

Mashpee Pond

Triangle

Pond

Spectacle

Pond

Lawrence

Pond

Long

Pond

Santuit

Pond

Lovells

Pond

Snake Pond

Weeks

 Pond

71o 70o

42o30'

41o

30'

MASSACHUSETTS

Cape Cod

Atlantic Ocean

Study Area

0 10 20 MILES

250,000

0 10 20 KILOMETERS

330,000 895,000

815,000

Northings and eastings shown are in state plane meters.

State Plane Coordinate System Datum is NAD 83

Massachusetts 

Military Reservation 

East Wareham

EXPLANATION

WATER-TABLE CONTOUR — Shows simulated 

altitude of water table, in feet above NGVD 29. 

Contour interval is 1 foot (Walter and Whealan, 2004)

MASSACHUSETTS MILITARY 

RESERVATION BOUNDARY

MONITORING WELL AND NUMBER

OTIS AIR BASE WEATHER STATION

Figure 1. Southeast Ranges of Camp Edwards military-training area, the simulated water table, monitoring wells, and the 

locations of NOAA weather stations KFMH on Otis Air National Guard Base, western Cape Cod, Massachusetts, and at East 

Wareham, Massachusetts.

   Ground-Water Levels near the Top of the Water-Table Mound
Water-Level and Precipitation 

Observations

Water-level data and daily precipitation records were 

examined to determine the relation between precipitation and 

changes in the water levels. Water-level data were collected 

from three previously installed observation wells near the top 

of the water-table mound. The wells are in the same general 

area near the Southeast Ranges of Camp Edwards, have different depths to water, and have construction characteristics 

that are favorable for continuous monitoring of water levels 

(table 1). The depths to water, or unsaturated-zone thickness, 

at the wells are representative of the range of depths to water 

on most of western Cape Cod, and vary spatially because of 

the undulating topography associated with the glacial origin of 

the Cape.

Daily precipitation data from the National Oceanic 

and Atmospheric Administration (NOAA) Weather Station, 

KFMH, at Otis Air National Guard Base (ANGB), Mashpee, 

MA, was used in this investigation. This data set also was 

used to compute an estimate of recharge. Missing data from 

weather station KFMH were estimated from NOAA records 

from the nearby East Wareham, MA, weather station.

Water-Level-Monitoring Equipment

The water-level-recording device used in this study was 

the In-Situ MiniTROLL. The MiniTROLL includes a downhole pressure sensor and datalogger suspended at a fixed depth 

by a data-retrieval cable with a coaxial vent tube. The device 

was suspended below the water surface in each well within the 

range recommended by the manufacturer. Periodic measurements of the depth to water were made manually with a Slope 

Indicator electrical water-level tape to check the operation of 

each continuous-recording device. Manufacturer specifications 

for the devices are listed in table 2. The ground-water-level 

data are available from the USGS Massachusetts-Rhode Island 

Water Science Center http://ma.water.usgs.gov.

Precipitation Measurements

Precipitation and temperature data were obtained from 

NOAA weather stations close to the observation wells 

(tables 3 and 4). Otis Weather Station KFMH is adjacent to 

the airfield control tower at Otis ANGB, about 3 mi south of 

the observation wells (fig. 1). A contractor to the Air National 

Guard operates the station to assist with flight operations. The 

climatological data are available from the Northeast Regional 

Climate Center at Cornell University, Ithaca, NY (Northeast 

Regional Climate Center, 2005) or in a provisional format 

online from NOAA National Weather Service daily climate 

data-retrieval site (National Oceanic and Atmospheric Administration, 2005). 

Estimation of Recharge

Precipitation that falls onto Cape Cod either evaporates 

from the land surface, is transpired by plants, falls directly into 

surface-water bodies, or infiltrates into the permeable ground. 

Very little water remains at the surface as overland flow on 

Cape Cod (LeBlanc and others, 1986). If the shallow soil is 

dry enough, some infiltrated water may be retained, where it 

can be taken up subsequently by plant roots and transpired. 

Water that moves below the root zone continues moving 

downward through the unsaturated zone and recharges the 

aquifer at the water table. Antecedent soil-moisture conditions 

determine whether or not water from a given rainfall event 

recharges the aquifer. The time between rainfall and corresponding recharge at the water table is controlled by many 

factors, including the antecedent soil-moisture conditions, the 

thickness of the unsaturated zone, and the hydraulic characteristics of the soil. Because only a portion of the precipitation 

recharges the aquifer, an estimate of daily recharge was made 

for comparison to the observed water levels (fig. 2).

Daily recharge was estimated for an 8-year period (calendar years 1997–2004) by using a soil-water balance approach 

(Thornthwaite and Mather, 1957) with inputs of daily measured precipitation, soil-moisture capacity (SMC), and daily 

estimated potential evapotranspiration (PET). Soil-moisture 

capacity is the quantity of moisture retained in the soil after 

excess moisture is drained through gravity drainage. The initial 5-year period (1997 to 2001) was included to ensure that 

effects of the estimated initial soil moisture used to start the 

calculations had diminished and that at least one yearly waterbudget cycle was balanced before calculations for the 3-year 

study period began (Thornthwaite and Mather, 1957). 

The PET estimates were obtained by two methods 

(Jensen and Haise, 1963; and Thornthwaite, 1948) from 

climatological data (maximum and minimum daily temperature, and daily solar radiation) measured at the Otis Weather 

Station. SMC values of 4 and 6 in., assumed to be reasonable 

for the sandy soils of Cape Cod (LeBlanc and others, 1986), 

were used in the analysis. The value used for SMC can affect 

the quantity of water available for recharge. If the amount of 

moisture in a soil is below the SMC, the soil-moisture deficit—the difference between the SMC and the quantity of soil 

moisture—must first be satisfied in the soil-water-balance 

calculation before water is available for recharge. The amount 

of water in the soil column that is in excess of the SMC after 

accounting for PET is water available for recharge.

Jensen and Haise (1963) developed an energy-balance 

approach for estimating PET on the basis of temperature and 

solar-radiation data. The Jensen and Haise PET estimates 

were calculated by using a graphical interface program called 

WDMUtil (Hummel and others, 2001) that allows users to 

import and operate on meteorological data files. WDMUtil 

contains algorithms to calculate daily PET by the Jensen and 

Haise (1963), Hamon (1961), and Penman (1948) methods. 

Water-Level and Precipitation 0bservations 
   Ground-Water Levels near the Top of the Water-Table Mound

Table 1. Monitoring-well characteristics and water-level-recorder information, Camp Edwards, western Cape Cod, Massachusetts.

[MMR, Massachusetts Military Reservation; USGS, U.S. Geological Survey; ID, identification number; altitudes and depths in feet relative to NGVD 29]

MMR ID MW-1265 MW-1455 90MW0063

USGS Site ID 414219070313601 414139070311501 414124070311401

USGS Well No. MA-SDW 525-0109 MA-SDW 526-0040 MA-SDW 527-0055

Latitude 41°42’19.15” 41°41’39.31” 41°41’24.09”

Longitude 70°31’35.50” 70°31’15.46” 70°31’14.36”

Altitude, land surface 170.15 99.66 86.10

Altitude, top of well casing 169.43 99.12 85.93

Altitude, top of screen 71.15 69.66 36.10

Altitude, bottom of screen 61.15 59.66 31.10

Approximate depth to water 

below land surface 101 30 18

Depth of pressure sensor below 

land surface 107 38 25

Approximate depth of submergence of pressure sensor 6 8 8

Table 2. Characteristics of automated water-level-recording and manual-measurement devices.

[psig, pounds per square inch gage; in., inch; ft, feet; psi, pounds per square inch]

Descriptor Specifications

In-Situ MiniTROLL

Device type Submersible pressure transducer, data logger, vented cable

Make and model In-Situ MiniTROLL, internal power, 30 psig

Specifications 11.65-in. long, 0.72-in. diameter, 69-ft measurement range

Pressure sensor Silicon strain-gage

Range and accuracy 30 psi (69 ft), 0.1% full scale

Measurement frequency 30 minutes (adjustable)

Water-level tape

Make and model Sinco Slope Indicator electrical water-level tape

Specifications 150 ft long, 0.01-ft divisions
Figure 2. A, Manual measurements and hydrographs of continuous water levels recorded in three wells between the Southeast 

Ranges of Camp Edwards and Snake Pond, western Cape Cod; B, estimated daily recharge; and C, daily precipitation recorded 

at NOAA Weather Station KFMH on Otis Air National Guard Base, western Cape Cod, Massachusetts, from January 9, 2002, to 

December 31, 2004. Dashed lines indicate gaps in the record during periods of equipment malfunction.

Water-Level and Precipitation Observations   

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ALTITUDE, IN FEET ABOVE NGVD 29

MA-SDW 525-0109

MA-SDW 526-0040

MA-SDW 527-0055

Manual measurements

2002 2003 2004

JAN.

MAY

SEPT.

JAN.

MAY

SEPT.

JAN.

MAY

SEPT.

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ESTIMATED RECHARGE,

 IN INCHES

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A.

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   Ground-Water Levels near the Top of the Water-Table Mound

The Jensen and Haise method uses minimum and maximum 

daily temperature, daily solar radiation, and two calculated 

coefficients. The daily PET estimates calculated by the 

WDMUtil program, the daily precipitation, and a value for 

SMC were used as input to a separate FORTRAN program 

that calculated a daily soil-water balance based on the method 

of Thornthwaite and Mather (1957). This program uses the 

soil-moisture value from the previous day to calculate the 

daily water-balance for the current day using precipitation and 

PET. Estimates of daily recharge are the result. 

The second method used to estimate PET was developed 

by Thornthwaite (1948) and uses an empirical approach on the 

basis of temperature and day-length estimates. The Thornthwaite approach is used in a FORTRAN computer program 

called WATBUG (Willmott, 1977), which calculates daily or 

monthly water budgets. Daily calculations use average daily 

temperature, latitude, daily precipitation, and a value for SMC 

as input. In this water-balance program, daily temperature and 

latitude data were used to calculate daily Thornthwaite PET. 

WATBUG computes a daily accounting of precipitation, PET, 

and soil moisture to calculate a daily recharge estimate. 

Recharge estimates based on the Jensen and Haise and 

Thornthwaite PET methods are similar. The average annual 

recharge estimates for the entire study period 2002 to 2004 

based on the Thornthwaite PET method for SMCs of 4 in. 

and 6 in. were 24.5 in/yr and 23.5 in/yr, respectively; recharge 

estimates by the Jensen and Haise PET method for SMCs of 

4 in. and 6 in. were slightly lower, 24.3 in/yr and 22.7 in/yr, 

respectively (table 5). Yearly recharge estimates for both PET 

methods were slightly lower for SMC of 6 in. (about 3 to 11 

percent) than recharge estimates for a SMC of 4 in. (table 5). 

These recharge estimates are similar to those reported 

by LeBlanc and others (1986) despite the different periods of 

record. LeBlanc and others (1986) used the Thornthwaite and 

Mather (1957) method to estimate an average annual recharge 

rate of about 20 in/yr for the period 1961 to 1976 for several 

locations on Cape Cod, and 22.6 in/yr for the period 1947 to 

1976 for East Wareham, MA. Average annual precipitation 

was about 44 in. for the period 1961 to 1976 for Cape Cod, 

MA, and 43.7 in. for the period 1947 to 1976 for East Wareham, MA. Average annual precipitation recorded at the Otis 

Weather Station for 2002 to 2004 was 42.7 in. The annual 

precipitation in 2003 was 51.30 in. (table 3) whereas the 

estimated 30-year average annual precipitation for the region 

surrounding the wells is 46.6 in (table 4). The greater recharge 

estimate for 2002–04 than for 1961–76 probably reflects the 

substantially higher-than-average precipitation in 2003 

(table 3).

Because the Jensen and Haise PET method uses a greater 

variety of available measured data than the Thornthwaite 

method, and the recharge values for the two values of SMC 

are similar, daily recharge estimates based on the Jensen and 

Haise PET method with a SMC of 4 in. are used in this report 

for comparison to the ground-water levels.

The rates of recharge presented in this report help 

illustrate the relation between precipitation and ground-water 

levels, but the estimates are uncertain for several reasons. The 

PET estimates are based on empirical methods that have not 

been field-verified by independent methods on Cape Cod. 

Other methods would likely yield different results. The soilwater-balance method only approximates complex hydraulic 

processes, including the important effect of SMC, in the soil 

zone. Finally, the climatological data were collected at a site 

about 3 mi from the wells (fig. 1), and these data could differ 

from the corresponding values at the well sites.

Ground-Water Levels at Camp Edwards

The altitude and shape of the water table beneath Cape 

Cod vary with time because of the dynamic balance between 

recharge from inflows, including precipitation and wastewater 

disposal; and outflows, including ground-water flow to the 

coast and streams, and water pumped from wells. Therefore, 

the top of the water-table mound generally falls during dry 

periods and rises during wet periods. Additionally, the location of the top of the mound moves as water levels rise and fall 

(Walter and Masterson, 2003).

Soil-moisture conditions, evaporation, interception, and 

plant transpiration play major roles in controlling the amount 

of water that passes from the land surface through the unsaturated zone to recharge the aquifer. Precipitation falling during 

the summer or after a prolonged dry period may contribute 

less recharge than an equivalent volume of precipitation during 

other times of the year. The thickness of the unsaturated zone 

also plays a role in controlling the timing of the response of 

water levels to recharge. 

Response of Ground-Water Levels to Long-Term 

Precipitation Trends

Annual precipitation is, on average, evenly distributed 

over the year, but can vary substantially from year to year. 

During the 4-year period May 1998 through summer 2002, 

precipitation was as much as 60 percent below normal 

(table 3). As a result, when continuous recording of water levels began in January 2002, the region was already in a drought. 

Water levels in wells near the top of the water-table mound 

were declining steadily and declined an additional 2–3 ft from 

January to October 2002 (fig. 2A).

USGS observation well MA-SDW 253, near Triangle 

Pond in Sandwich, MA, about 3.5 miles east of the MMR, is 

screened in the same aquifer as the wells used in this study 

(fig. 1). The historical range (1963–2004) in water-level 

fluctuation at this well is about 10 ft. The hydrographs for 

the three study wells correspond closely to the hydrograph for 

well MA-SDW 253 during the period 2002–04 (fig. 3). The 

ground-water level at well MA-SDW 253 in November 2002 

was only 0.32 ft above the record-low level observed at this 

site in 1967 (fig. 3A). Therefore, it is likely that the hydrographs of the three wells captured the most severe period of 
drought since the 1960s. This comparison also suggests that 

the water levels in the study wells can be expected to fluctuate 

about 10 ft between extreme low and high levels.

Weather patterns changed in November 2002 and brought 

greater-than-normal rainfall and recharge; almost 7 in. of precipitation was recorded at the Otis Weather Station during that 

month (table 3). As a result, water levels in the wells began to 

rise. Rising water levels were observed first in the well with 

the shallowest depth to water (MA-SDW 527-0055) (fig. 2A). 

The water level began to rise shortly thereafter in the well with 

the intermediate depth to water (MA-SDW 526-0040). About 

a month later, water levels began to rise in the well with the 

greatest depth to water (MA-SDW 525-0109).

Slightly above average precipitation (table 3) continued 

during 2003. An annual total of 51.30 in. was recorded at 

the Otis Weather Station, even though May and July were 

relatively dry months with 1.93 and 1.54 in. of rainfall, 

respectively (table 3). This increased precipitation resulted 

in substantial recharge through June 2003. Water levels rose 

rapidly in all three wells through this period. Recharge to the 

aquifer decreased despite the rainfall, however, as the summer 

growing season began. The hydrographs began to level off for 

the shallowest well (MA-SDW 527-0055) first. Soon thereafter, the hydrograph for the intermediate well (MA-SDW 526-

0040) began to flatten. About 1.5 months later, the deepest 

well (MA-SDW 525-0109) followed the same pattern. Water 

levels in all three wells rose more than 4 ft during the first half 

of the year, and with water levels at or slightly above their 

long-term averages at wells across the region (for example, 

MA-SDW 253), it was clear that the drought had ended.

While rebounding from the drought, water levels in the 

three wells rose almost continuously from March to August 

2003 at an average rate of about 0.64 ft per month (0.021 ft/d) 

(fig. 2A). During this period, the levels rose about 4.5 ft, and 

the total estimated recharge was about 1 ft. If the rise was 

directly proportional to the amount of recharge, the estimated 

specific yield is about 0.2, which is a reasonable value for sand 

and gravel.

Little recharge was produced by precipitation in summer 

2003; therefore, water levels began to decline slowly (fig. 2). 

This is the normal seasonal pattern for this area. Substantial 

recharge began again in late October 2003 at the end of the 

growing season, and continued through the winter. Some precipitation fell as snow during the study period and was frozen 

at the surface; however, snow and ice generally persist for only 

short periods on Cape Cod except during extended cold periods. Windy conditions over a frozen snowpack can contribute 

to substantial moisture loss through sublimation (Fassnacht, 

2004). This loss of potential recharge is not considered in this 

report.

The water-level altitudes in the three wells changed 

relative to one another several times during the study period 

(fig. 2A) The water-level altitude at well MA-SDW 525-0109 

changed from the highest to the lowest among the three wells 

in the spring and summer of 2002, and remained the lowest 

until July 2003. During periods of low water levels, it appears 

that the water table at this well, which is about 1 mi north of 

the other two observation wells (fig. 1), declines to the lowest 

altitude among the three wells. However, during times of high 

water levels resulting from periods of increased recharge, the 

water table at this northernmost well rises to the highest altitude among the three wells. Data from summer 2003 indicate 

that the water level in well MA-SDW 525-0109 was steadily 

rising and, by early September 2003, again was highest among 

the three wells (fig. 2A).

The change in relative water-table altitudes among the 

wells indicates a southeastward shift of the top of the watertable mound when water levels are low, such as fall 2002, 

and a gradual northwestward shift when water levels rise 

regionally, during 2003 for example. The phenomenon is 

complicated by the lag in response to recharge due to the thick 

unsaturated zone at well MA-SDW 525-0109, but ultimately, 

when water levels are high (early 2002 and late 2003 are two 

examples (fig. 2)), the mound shifts to the northwest. This 

relation is consistent with ground-water-flow simulations 

(Walter and Masterson, 2003) that indicate that the top of the 

mound moves along a line generally oriented northwest to 

southeast as regional water levels fluctuate.

Changes in Ground-Water Levels with Individual 

Precipitation Events

Several general relations were evident from the comparison of water levels to recharge estimated from precipitation and climate records. Because of the dry period preceding installation of the measuring equipment, the amount of 

recharge reaching the water table from precipitation was 

insufficient to reverse the declining water-level trend observed 

throughout most of 2002. During a 9-day period starting on 

May 10, 2002, however, 3.3 in. of rain fell (fig. 4), with more 

than 2 in. falling over the first 5 days of the period. The water 

level in well MA-SDW 527-0055, the well with the shallowest depth to water, began to rise on about May 13, probably in response to the recent rain and an estimated 1.06 in. 

of recharge from the 1.6 in. of rain on May 13. The rate of 

water-level decline in well MA-SDW 526-0040, the well with 

an intermediate depth to water, decreased to near zero at about 

the same time, and by May 18, after an additional 1.25 in. of 

rain (0.92 in. of recharge), the water level in this well began 

rising. In contrast, the water level in MA-SDW 525-0109, the 

well with the greatest depth to water, continued to decline until 

mid-June, when water levels rose briefly, perhaps in response 

to recharge from the mid-May precipitation. This would indicate a 1-month time lag between the mid-May recharge events 

and the response of the water level at the site.

Although water levels in the three wells rose in apparent 

response to the substantial precipitation in May 2002, precipitation and water-level rises were only weakly correlated in 

this study (fig. 2) because the amount of recharge that results 

from a given storm is affected by evapotranspiration rates and 

antecedent soil-moisture conditions. For example, the storms 

in June 2002 (fig. 4) appear to have resulted in little or no 

Ground-Water Levels at Camp Edwards 
Table 3. Monthly and annual precipitation at National Oceanic and Atmospheric Administration Weather Station KFMH at Otis Air National Guard 

Base, western Cape Cod, Massachusetts, 1998–2004. [All precipitation values in inches]

YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANNUAL

1998 5.27 4.99 5.45 4.09 2.08 6.10 1.88 2.49 2.87 2.93 1.97 1.22 41.34

1999 3.47 2.37 3.75 0.53 1.51 0.27 1.00 1.82 3.32 3.60 2.56 2.22 26.42

2000 2.95 2.69 3.12 4.45 3.77 1.73 2.43 3.11 1.70 2.68 2.64 2.15 33.42

2001 2.38 2.46 7.18 1.99 3.16 3.36 2.36 4.65 2.15 2.38 2.26 4.03 38.36

2002 4.43 2.25 4.58 3.07 3.95 2.78 0.32 1.25 4.59 2.94 6.73 3.47 40.36

2003 3.61 5.26 7.15 4.47 1.93 4.26 1.54 4.79 2.85 5.08 2.40 7.96 51.30

2004 1.84 2.64 2.41 4.82 2.44 1.76 1.43 5.36 6.35 1.41 2.33 3.74 36.53

Mean 3.42 3.24 4.81 3.35 2.69 2.89 1.57 3.35 3.40 3.00 2.98 3.54 38.25

Table 4. Mean monthly and annual precipitation for the period 1971 to 2000 at three National Oceanic and Atmospheric Administration weather stations near Otis Air National Guard Base, western Cape Cod, Massachusetts. [Data from National Climate Data Center (2002). All precipitation values in inches]

Station JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANNUAL

EAST WAREHAM 4.54 3.72 4.56 4.39 3.73 3.57 3.23 4.07 4.06 3.89 4.52 4.49 48.77HATCHVILLE 4.21 3.50 4.41 4.40 3.48 3.82 3.16 3.92 3.91 4.41 4.30 4.46 47.98HYANNIS 4.06 3.29 3.94 3.76 3.23 3.21 2.81 3.50 3.33 3.91 3.87 4.12 43.03

3-Station-Mean 4.27 3.50 4.30 4.18 3.48 3.53 3.07 3.83 3.77 4.07 4.23 4.36 46.59

 Ground-Water Levels near the Top of the Water-Table Mound
1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

MA-SDW 253

MA-SDW 525-0109

A.

B.

1/1/2002 1/1/2003 1/1/2004 12/31/2004

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

MA-SDW 525-0109

MA-SDW 526-0040

MA-SDW 527-0055

MA-SDW 253

YEAR

ALTITUDE, IN FEET ABOVE NGVD 29 ALTITUDE, IN FEET ABOVE NGVD 29

Figure 3. A, Monthly water levels measured manually in USGS well MA-SDW 253, 1962–2004, and continuously in well MASDW 525-0109, 2002–2004; and B, water levels measured manually in wells MA-SDW 525-0109, MA-SDW 526-0040, and MASDW 527-0055 near the Southeast Ranges of Camp Edwards at the top of the water-table mound, and in well MA-SDW 253 east 

of Camp Edwards, on western Cape Cod, Massachusetts, 2002–04.

Ground-Water Levels at Camp Edwards   
recharge because of substantial direct evaporation to the atmosphere, increased transpiration by plants, and further replenishment of soil moisture. Therefore, water levels declined 

throughout the summer and early fall 2002, despite normal 

rainfall in August and September 2002 (fig. 2). 

In late 2002, several frequent precipitation events contributed substantial recharge. The recharge estimate for this time 

period suggests that nearly all of the incoming precipitation 

contributed to recharge of the aquifer (fig. 5), and water levels 

in all three wells began to climb dramatically; however, about 

a month passed before the level in the deepest well began to 

rise. Water levels continued to rise through summer 2003. 

During this period of rapidly rising water levels, the effects 

of individual recharge events are impossible to discern on the 

hydrograph (fig. 2). 

The next obvious response of water levels to recharge 

occurred around April 1, 2004, when 1.68 in. of estimated 

recharge was produced by 1.69 in. of precipitation. The 

water levels in the two wells with shallower depths to water 

(MA-SDW 526-0040 and MA-SDW 527-0055) rose almost 

immediately, whereas water levels in the well with the greatest 

depth to water (MA-SDW 525-0109) showed little change in 

trend for about another month (fig. 2).

Summary

From January 2002 through December 2004, the USGS, 

in cooperation with the Army Environmental Center at the 

Massachusetts Military Reservation, measured water levels 

in three wells near the top of the water-table mound beneath 

western Cape Cod. The purpose of the measurements was 

to characterize the responses of the water levels as a function of the unsaturated-zone thickness. In January 2002, the 

region was in a drought, and the water-level hydrographs 

from the wells reflected the extremely dry period during most 

of 2002. During the first year of record, water levels in the 

three wells at the top of the water-table mound fell more than 

2 ft. Water levels at a nearby well with 41 years of record 

declined to within a foot of the record-low level for the same 

period (1963–2004). As the water table declined, a change 

in the relative position of water-level altitudes in the three 

wells was recorded that supports a model-predicted northwest 

to southeast shift in the position of the top of the water-table 

mound during dry periods. The observed changes in altitude 

and position of the top of the water-table mound are related to 

changes in recharge from precipitation. Greater than normal 

precipitation brought increased recharge starting in Novem5/1/2002 5/31/2002 7/1/2002 8/1/2002

65

66

67

0

1

2

3

4

PRECIPITATION AND ESTIMATED RECHARGE, IN INCHES

ALTITUDE, IN FEET ABOVE NGVD 29 

MA-SDW 525-0109

MA-SDW 526-0040

MA-SDW 527-0055

Precipitation

Estimated recharge

Manual measurements

Figure 4. Continuous water levels recorded in three wells between the Southeast Ranges of Camp Edwards and Snake Pond, 

western Cape Cod, with bar graphs of precipitation and estimated recharge, May through July 2002. Daily precipitation was 

recorded at NOAA Weather Station KFMH at Otis Air National Guard Base, western Cape Cod, Massachusetts. 

10 Ground-Water Levels near the Top of the Water-Table Mound
11/1/2002 12/1/2002 1/1/2003 2/1/2003

63

64

65

66

MA-SDW 525-0109

MA-SDW 526-0040

MA-SDW 527-0055

Precipitation

Estimated recharge

Manual measurements

0

1

2

3

4

PRECIPITATION AND ESTIMATED RECHARGE, IN INCHES

ALTITUDE, IN FEET ABOVE NGVD 29

Table 5. Estimated recharge determined from two daily soil-water balance approaches—Jensen and Haise (1963) and Thornthwaite 

(1948)—and annual precipitation at Otis Air National Guard Base, western Cape Cod, Massachusetts, 2002–04.

[in., inch; in/yr, inches per year]

Recharge Precipitation

Calculation Annual recharge (in/yr)

Method of potential 

evapotranspiration (PET) 

calculation 

Soil-moisture 

capacity (in.)

2002 2003 2004 3-year average Year Annual precipitation (in.)

Jensen and Haise 4 23.7 31.4 17.8 24.3 2002 40.4

Thornthwaite 4 23.6 31.5 18.4 24.5 2003 51.3

Jensen and Haise 6 21.7 30.6 15.8 22.7 2004 36.5

Thornthwaite 6 22.2 30.7 17.4 23.5 mean 42.7

Figure 5. Continuous water levels recorded in three wells between the Southeast Ranges of Camp Edwards and Snake 

Pond, western Cape Cod, with bar graphs of precipitation and estimated recharge, November 2002 through January 2003. 

Daily precipitation was recorded at NOAA Weather Station KFMH at Otis Air National Guard Base, western Cape Cod, 

Massachusetts. 

Summary 11
ber 2002, which in turn caused the rise in water levels and a 

reversal in the relative water-table altitudes in the wells by 

September 2003. The responses of the water levels to individual precipitation events depended on the depth to water in 

the three wells, with the response in the well with the thickest 

unsaturated zone lagging about a month behind the response in 

the other two wells. This lag may reflect the effects of water 

movement through the thick unsaturated zone. The waterlevel information from this observation-well network provides 

valuable information on the dynamic ground-water system 

beneath the MMR. 

Acknowledgments

The authors thank Timothy Dwyer and Thomas Remmers 

of Shaw Group (formerly of AMEC Earth & Environmental, 

Inc.) for their assistance in providing access to the wells. We 

are grateful to Ronald Busciolano, U.S. Geological Survey 

Water Science Center, Coram, New York, and Roy Socolow, 

U.S. Geological Survey MA-RI Water Science Center, for 

their technical reviews, and Mary Ashman, U.S. Geological Survey MA-RI Water Science Center, for her editorial 

review; their reviews greatly enhanced this report. We also 

thank Rose Forbes of the Air Force Center for Environmental 

Excellence (AFCEE) Installation Restoration Program at the 

MMR for the use of one of the program’s monitoring wells in 

this effort. Finally, we thank Benjamin Gregson and David 

Hill of the Army Environmental Center (AEC) of the Impact 

Area Groundwater Study Program (IAGWSP) for their support 

during this study. 

References

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in Climatology, v. 10, no. 3, 311 p.

12 Ground-Water Levels near the Top of the Water-Table Mound
Walter, D.A., and Masterson, J.P., 2003, Simulation of 

advective flow under steady-state and transient recharge 

conditions, Camp Edwards, Massachusetts Military 

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References 13
For additional information write to:

Director, USGS Massachusetts–Rhode Island Water Science Center

10 Bearfoot Road,

Northborough, MA 01532

or visit our Web site at

http://ma.water.usgs.gov