U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2010–5087

Prepared in cooperation with the 

Chester County Water Resources Authority and the Chester County Health Department 

Groundwater-Quality Monitoring Program

in Chester County, Pennsylvania, 1980–2008
Front cover—Well CH-3289 in eastern Chester County, Pennsylvania, sampled by the U.S. Geological Survey in 1988 as part of the 

Chester County groundwater-quality monitoring program. (Photograph taken by Arthur Lilienthal, U.S. Geological Survey, Exton, 

Pennsylvania, 2009.) 
Groundwater-Quality Monitoring Program 

in Chester County, Pennsylvania,

1980–2008

By Lisa A. Senior and Ronald A. Sloto

Prepared in cooperation with the Chester County Water Resources Authority and 

the Chester County Health Department

Scientific Investigations Report 2010–5087

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2010

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Senior, L.A., and Sloto, R.A., 2010, Groundwater-quality monitoring program in Chester County, Pennsylvania, 1980–

2008: U.S. Geological Survey Scientific Investigations Report 2010-5087, 83 p.
iii

Contents

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

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

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

Description of Study Area ...................................................................................................................2

Hydrogeologic Setting ................................................................................................................2

Land Use........................................................................................................................................2

Previous Studies ...................................................................................................................................4

Well, Spring, and Stream Identification System..............................................................................6

Chester County Groundwater-Quality Monitoring Program...................................................................6

Results of Sampling for Constituents Associated with Land Uses and Human Activities .......9

Uncontrolled Landfills, Dumps, and Industrial Waste Discharges......................................9

Agricultural Use of Pesticides and Nitrate............................................................................17

Countywide Investigations..............................................................................................17

Octoraro Creek Investigation..........................................................................................17

Deicing Salts on Highways and Salt Storage Areas............................................................18

On-Site Wastewater Disposal .................................................................................................20

Other Localized Land Uses and Targeted Areas ..................................................................21

Cemeteries.........................................................................................................................21

County Parks and Other County-Owned Land .............................................................23

General Land-Use Assessments....................................................................................24

Pre-Development Groundwater and Base-Flow Quality in Beaver Creek Basin

in 2007....................................................................................................................24

Chloride as Indicator of Land-Use Change ...........................................................................27

Well-Water Samples ........................................................................................................27

Stream Base-Flow Samples............................................................................................27

Results of Sampling for Naturally Occurring Constituents..........................................................30

General Water Chemistry—pH, Alkalinity, Major Ions, Iron, and Manganese ...............30

Radionuclides.............................................................................................................................30

Radium and Radon............................................................................................................30

Gross Alpha-Particle and Beta-Particle Activity and Other Radionuclides ...........31

Arsenic.........................................................................................................................................33

Lead .........................................................................................................................................34

Summary and Conclusions.........................................................................................................................38

References Cited..........................................................................................................................................40

Appendix 1.....................................................................................................................................................45
iv

Figures

1. Map showing generalized geology of Chester County, Pa....................................................3

2. Map showing land use in 2000 in Chester County, Pa., and location of selected

parks and other county-owned land .........................................................................................5

3. Map showing National Priority List (Superfund) and Resource Conservation and

Recovery Act (RCRA) sites in Chester County, Pa., and locations of wells sampled

through the Chester County groundwater-quality monitoring program that had

detections of volatile organic compounds .............................................................................14

4. Map showing location of base-flow samples collected as part of the Chester

County groundwater-quality monitoring program and selected other areas of

base-flow sampling, 1966 through 2008, Chester County, Pa..............................................16

5. Map showing nitrate concentrations in base-flow samples from 7 tributaries to

Octoraro Creek and in groundwater samples from 21 wells in those tributary

basins, Chester County, Pa., 2000.............................................................................................19

6. Graphs showing chloride concentrations in base flow sampled annually in 

autumn at USGS streamgages: (A) 01479800 East Branch Red Clay Creek near

Five Points, Pa., 1970–2007; (B) 01480653 East Branch Brandywine Creek near 

Glenmoore, Pa., 1969–2007; (C) 01472157 French Creek near Phoenixville, Pa.,

1969–2007; (D) 01472080 Pigeon Creek near Slonaker, Pa., 1969–2007; and

(E) 01472190 Pickering Creek near Phoenixville, Pa., 1967–2007 ........................................28

7. Graphs showing radium-224 activities in relation to (A) gross alpha-particle

activities and (B) radium-228 activities in samples from 14 wells in 9 different

geologic units, Chester County, Pa., 1999...............................................................................32

8. Graphs showing relation between 72-hour gross alpha-particle activities and

30-day gross alpha-particle activities in groundwater samples from 18 wells in the

Chickies Quartzite or Antietam and Harpers Formation, undivided, Chester County,

Pa., 2003........................................................................................................................................33

9. Graphs showing relation between 30-day gross alpha-particle activities and pH in

groundwater samples from 18 wells in the Chickies Quartzite or Antietam and

Harpers Formation, undivided, Chester County, Pa., 2003 ...................................................33

10. Graph showing relation between concentrations of dissolved and total lead and pH

in groundwater samples from 17 wells in the Chickies Quartzite or Antietam and

Harpers Formation, undivided, Chester County, Pa., 2003 ...................................................35

11. Graph showing relation between lead-210 activities and radon-222 activities in

groundwater samples from 17 wells in the Chickies Quartzite or Antietam and

Harpers Formation, undivided, Chester County, Pa., 2003 ...................................................35

12. Graph showing relation between pH and the ratio of dissolved to total lead

concentrations in groundwater samples from 17 wells in the Chickies Quartzite or

Antietam and Harpers Formation, undivided, Chester County, Pa., 2003 ..........................37
v

Tables

1. Contaminants or constituents of concern in groundwater that are commonly

associated with various land uses for the Chester County groundwater-quality

monitoring program, 1980–2008..................................................................................................4

2. Number and type of sites sampled and reason for sample collection listed by

possible contaminant source for the Chester County groundwater-monitoring

program, 1980-2008.......................................................................................................................7

3. Maximum contaminant levels, health advisories, and secondary maximum

contaminant levels established by the U.S. Environmental Protection Agency 

for selected constituents in drinking water............................................................................10

4. Concentrations of volatile organic compounds detected in wells sampled more

than once, Chester County, Pa. ................................................................................................12

5. Concentrations of chloride, boron, nitrate, and orthophosphate detected in

samples from nine wells in residential areas with on-site wastewater disposal in

use since the 1970s, Chester County, Pa ................................................................................21

6. Concentrations of nitrate, orthophosphate, chloride, boron, and organic

wastewater compounds detected in samples from five wells and five streams in

headwater areas that have residential land use with on-site wastewater disposal,

Chester County, Pa., 2008 ..........................................................................................................22

7. Concentrations of formaldehyde and lead and pH detected in samples from 10

wells near cemeteries, Chester County, Pa., 1990 through 1997 ........................................23

8. Concentrations of nitrate, chloride, boron, and organic wastewater compounds

detected in nine base-flow samples and two well-water samples near Beaver

Creek Reservoir and in base-flow samples at five other stream sites collected in

2007 as part of the Chester County groundwater-quality monitoring program,

Chester County, Pa. ....................................................................................................................25
vi

Conversion Factors and Abbreviations

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)

Area

acre 4,047 square meter (m2)

acre 0.4047 hectare (ha)

acre 0.4047 square hectometer (hm2) 

acre 0.004047 square kilometer (km2)

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

Radioactivity

picocurie per liter (pCi/L) 0.037 becquerel per liter (Bq/L) 

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C=(°F-32)/1.8

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.

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).
Abstract

The U.S. Geological Survey in cooperation with the 

Chester County Water Resources Authority and the Chester 

County Health Department began a groundwater-quality 

monitoring program in 1980 in Chester County, Pa., where a 

large percentage of the population relies on wells for drinkingwater supply. This report documents the program and serves as 

a reference for data collected through the program from 1980 

through 2008.

The initial focus of the program was to collect data on 

groundwater quality near suspected localized sources of contamination, such as uncontrolled landfills and suspected industrial wastes, to determine if contaminants were present that 

might pose a health risk to those using the groundwater. Subsequently, the program was expanded to address the effects of 

widely distributed contaminant sources associated with agricultural and residential land uses on groundwater quality and 

to document naturally occurring constituents, such as radium, 

radon, and arsenic, that are potential hazards in drinking water. 

Since 2000, base-flow stream samples have been collected 

in addition to well-water and spring samples in a few small 

drainage areas to investigate the relation between groundwater 

quality and stream base-flow quality. The program has primarily consisted of spatial assessment with limited temporal data 

collected on groundwater quality. Most data were collected 

through the monitoring program for reconnaissance purposes 

to identify and locate groundwater-quality problems and 

generally were not intended for rigorous statistical analyses 

that might determine land-use or geochemical factors affecting 

groundwater quality in space or through time.

Results of the program found several contaminants associated with various land uses and human activities in groundwater in Chester County. Volatile organic compounds (such 

as trichloroethylene) were measured in groundwater near 

suspected localized contaminant sources in concentrations 

that exceeded drinking-water standards. Groundwater in 

some agricultural areas had concentrations of nitrate and 

some pesticides that exceeded drinking-water standards. 

Elevated concentrations of chloride were measured near salt 

storage areas and highways. Formaldehyde was detected in 

groundwater near cemeteries. In residential areas with on-site 

wastewater disposal, effects on groundwater quality included 

elevated nitrate concentrations and low concentrations of 

volatile organic compounds and wastewater compounds, such 

as antibiotics and detergents. Base-flow samples indicated 

that groundwater discharge to streams carried contaminants 

such as nitrate, pesticides, wastewater compounds, and 

other contaminants.

Radionuclides, including radium-226, radium-228, 

radium-224, and radon-222, and gross alpha-particle activity 

were measured in groundwater at levels above established and 

proposed drinking-water standards in some geologic units, 

particularly in quartzite and quartzite schists. Arsenic concentrations above drinking-water standards were measured in a 

few samples and were most likely to occur in groundwater in 

the shales and sandstones in the northern part of the county. 

Other potential natural hazards, such as lead from aquifer 

materials or leached from plumbing because of low pH, were 

present in concentrations above drinking-water standards 

infrequently (less than 10 percent of samples).

Limited temporal sampling suggested that chloride 

concentrations in groundwater increased in the county since 

the program began in 1980 through 2008, reflecting increasing 

population and urbanization in that period.

Introduction

The groundwater-quality monitoring program conducted 

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

the Chester County Water Resources Authority (CCWRA) and 

the Chester County Health Department (CCHD), in Chester 

County, Pa., began in 1980 in response to environmental 

health concerns of the time. In the late 1970s, contamination 

of the environment, including groundwater, from landfills 

and various commercial and industrial waste-disposal activities had become an issue in the United States, prompting the 

U.S. Congress to pass the Comprehensive Environmental 

Response, Compensation and Liability Act (CERCLA) of 

1980 to address the identification and cleanup of contaminated 

areas. Because groundwater is an important source of water 

supply for domestic use in Chester County and because of 

the public-health concerns in the county, the CCWRA and the 

Groundwater-Quality Monitoring Program in Chester 

County, Pennsylvania, 1980–2008

By Lisa A. Senior and Ronald A. Sloto
2 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

CCHD wanted to obtain information about the extent, magnitude, and type of possible groundwater contamination, such as 

that being addressed under CERCLA (also known as Superfund). Thus, the CCWRA and CCHD worked with USGS to 

establish the Chester County groundwater-quality monitoring 

program to gather data for use in protecting the environment 

and public health of Chester County.

For the first few years, the focus of the monitoring 

program was in areas near suspected sources of uncontrolled 

landfill and industrial contamination. Through time, the 

program broadened in scope to include investigations of other 

sources of contamination including naturally occurring constituents that could pose risks to human health and the potential 

effects of various land uses. The monitoring program also 

supported other water-resource studies undertaken by USGS 

for the county.

Purpose and Scope

This report describes and documents the Chester County 

groundwater-quality monitoring program conducted by the 

USGS from its inception in 1980 through 2008. Results of 

sampling are summarized for each type of potential contaminant source targeted by the monitoring program. Results that 

have not been discussed in previous reports, including data 

collected after 2001, are presented with more detail.

In addition, the sampled sites are listed in an appendix by 

year, including the site identification numbers and the reason 

for sample collection. This reference appendix can be used to 

obtain detailed data from the USGS water-quality database for 

each site sampled.

Description of Study Area

Chester County is about 760 mi2 in area and lies in the 

Piedmont Physiographic Province in southeastern Pennsylvania. The topography is generally characterized by rolling 

hills and ranges in elevation from about 150 to 1,000 ft above 

NAVD 88. The county has a humid temperate climate and 

receives an average total annual precipitation of about 48 in. 

[30-year normal (1971–2000) precipitation for meteorological station West Chester 2 NW is 47.89 in. (National Oceanic 

and Atmospheric Administration, 2005)], which is distributed 

nearly evenly throughout the year. Chester County has 73 

municipalities including 1 city (Coatesville), 15 boroughs, and 

57 townships (see appendix).

Hydrogeologic Setting

The relatively complex geology of Chester County is 

made up of about 40 different mapped bedrock units consisting of Paleozoic-age and older metamorphic rocks, including phyllite, schist, limestone, marble, quartzite, and gneiss, 

and Mesozoic-age sedimentary (Triassic-age) and intrusive 

(Triassic- and Jurassic-age) rocks (fig. 1). Carbonate rocks, 

which are less resistant to erosion than the adjacent noncarbonate rocks, underlie the main east-west valley crossing the 

county. A more complete description of the geologic units in 

Chester County is given by Sloto (1994), although more recent 

geologic mapping in the southern two thirds of the county 

(Blackmer, 2004a, 2004b, 2005; Blackmer and Brown, 2006; 

Bosbyshell, 2006; Brown, 2006; Hill, 2006; Marquez, 2005; 

Wiswall, 2005) may supersede earlier mapping (Sloto, 1994) 

in some areas. Unconsolidated units consist of thin alluvial 

deposits that are quaternary in age or younger. Geologic 

names used in this report follow nomenclature established by 

the Pennsylvania Geological Survey and may not conform to 

USGS usage.

The rocks underlying Chester County form fractured-rock 

aquifers, where weathered bedrock (saprolite) and soil overlie 

the competent bedrock. Water-bearing properties differ by 

geologic unit (Sloto, 1994). Thickness of the saprolite varies 

but commonly is 10 to 40 ft. Soils in much of the county are 

moderately deep and well-drained, although the soils are thin 

and (or) poorly drained in some areas (Kunkle, 1963). Drilled 

wells generally are completed as open holes in the bedrock, 

with casing extending through the saprolite to the top of competent bedrock. Hand-dug wells dating from the period before 

drilled wells were common (by the early 20th century) generally are completed in the saprolite. Unconsolidated deposits in 

the county generally are not used as aquifers.

The fractured-rock aquifers are recharged locally by 

precipitation infiltrating through soils and saprolite to the 

bedrock. Groundwater flows through fracture openings in the 

bedrock and also in the saturated part of the saprolite. Under 

natural conditions, groundwater discharges to streams and 

springs. The water table generally is a subdued replica of the 

land surface, as shown by 27 maps of groundwater levels in 

the county (U.S. Geological Survey, 2006), such that groundwater flow paths commonly follow topography. Base flow 

(supplied by groundwater discharge to streams) comprises 

about 60 percent of total annual streamflow on average, as 

estimated from water budgets for several streams in Chester 

County (Sloto, 1994), and may be as high as about 80 percent 

of streamflow (Cinotto and others, 2005, p. 21).

Depth to water typically varies by topography; depths to 

water are greater under hilltops than on slopes or in valleys. 

Groundwater levels fluctuate seasonally because of changes 

in net recharge rates; depth to water is greatest in the fall and 

least in the spring. Although precipitation is distributed nearly 

evenly throughout the year, net recharge generally is greater in 

the cooler months (October–April), when evapotranspiration is 

reduced, than in the warmer months (May–September). Longterm average groundwater levels and base flow are highest in 

spring and lowest in fall in Chester County, Pa.

Land Use

Land use in Chester County is mixed, consisting largely 

of different types of agriculture (such as row crops, hay, mushroom growing and composting, nurseries, orchards, and dairy) 
Introduction 3

Figure 1. Generalized geology of Chester County, Pa.

76°5' 76° 75°55' 75°50' 75°45' 75°40' 75°35' 75°30' 75°25'

39°35'

39°40'

39°45'

39°50'

39°55'

40°

40°5'

40°10'

40°15'

0 5 10 MILES

0 8 16 KILOMETERS

EXPLANATION

Shale, sandstone

Gneiss

Carbonate

Quartzite, quartz-rich schist

Schist

Mafic, pegmatite

Municipality

West Chester

Kennett Square

Phoenixville

Downingtown

Coatesville

Oxford

Honey Brook

Lithology
4 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

with lesser amounts of wooded, residential, and other uses. In 

2000, about 39 percent of the land was agricultural, 27 percent 

wooded, 18 percent residential (mostly single-family), 11 percent industrial/commercial (including transportation and parking), and about 5 percent open, recreational, or vacant (fig. 2) 

(Delaware Valley Regional Planning Commission, 2004). In 

2005, the date of the most recent reported land use available, 

the relative proportion of each type of land use in the county 

was similar to the distribution in 2000 but with decreases in 

agricultural and undeveloped uses and increases in residential 

and other developed uses (industrial/commercial/transportation) (Delaware Valley Regional Planning Commission, 2008, 

2009).

Since the groundwater-quality monitoring program began 

in 1980, the amount of land in agricultural and forested uses 

decreased, and the amount of land in residential and commercial uses increased. From 1980 to 2000, the population in 

Chester County increased by 36.9 percent (116,841 people) 

(Delaware Regional Valley Planning Commission, 2001). 

From 2000 to 2005, the population increased 9 percent from 

433,510 to 473,880 (Delaware Valley Regional Planning Commission, 2009). This urbanizing trend is expected to continue. 

The population in Chester County is estimated to increase by 

31 percent (148,618 people) from 2005 to 2035 (Delaware 

Valley Regional Planning Commission, 2007).

Human activities associated with many land uses have 

the potential to change the quality of groundwater, including the introduction of contaminants that may pose a risk to 

human health. Some human activities or land uses may be a 

source of several contaminants. Some contaminants may have 

more than one source. For example, the presence of pesticides 

and elevated nitrate concentrations in groundwater may be 

associated with some agricultural activities. However, elevated 

nitrate in groundwater may be introduced not only through 

use of fertilizers in agricultural areas but also through on-site 

residential wastewater disposal, including septic systems. Possible contaminants or constituents of concern in groundwater 

that are commonly associated with various land uses are listed 

in table 1.

Previous Studies

Results of the Chester County groundwater-quality monitoring program have been published in part in several reports. 

Data collected through the program have been compiled with 

data collected for other studies in a data report by Sloto (1989) 

and in interpretive reports by Sloto (1990, 1994, 2000), Senior 

and others (1997), Senior (1998), and Ludlow and Loper 

(2004). Groundwater-quality data, including that collected 

as part of the groundwater-quality monitoring program and 

other studies, were compiled through 2001 in the most recent 

comprehensive interpretive report (Ludlow and Loper, 2004) 

and are discussed by constituent, with maps showing the distribution of concentrations that meet or exceed drinking-water 

standards or other statistical measures. The report by Ludlow 

and Loper (2004), however, does not include data collected 

prior to 1990 during the first 10 years of the Chester County 

groundwater-quality monitoring program for some constituents [common ions, metals, nutrients, pesticides, and volatile 

organic compounds (VOCs)].

Data collected solely through the Chester County 

groundwater-quality monitoring program were used to support 

the investigation of radium-224 (Senior and Sloto, 2000), 

the Elk Creek Basin study (Sloto, 2002), and a pilot study 

of the effect of on-site wastewater disposal on the quality of 

groundwater and base flow (Senior and Cinotto, 2007). Data 

collected largely through the groundwater-quality monitoring 

program were used to assess the occurrence of radon-222 in 

groundwater throughout the county (Senior, 1998). In addition, data collected through the program have been published 

with site location maps but without interpretation annually 

since 2000 (Durlin and Schaffstall, 2001a, 2001b, 2002, 2003, 

2005; Durlin and others, 2006; U.S. Geological Survey, 2007, 

2008, 2009).

Other USGS reports that describe aspects of groundwater 

quality in Chester County were based on studies funded and 

conducted separately from the monitoring program. These 

studies included effects of urbanization on eastern Chester 

County (Sloto, 1987), radium and radon in groundwater 

(Senior and Vogel, 1995), Red Clay Creek Basin assessment 

Table 1. Contaminants or constituents of concern in groundwater that are commonly associated with various land uses for the 

Chester County groundwater-quality monitoring program, 1980–2008.

[VOCs, volatile organic compounds]

Land use Contaminants or constituents of concern commonly associated with land use

Uncontrolled landfill, dump VOCs, ammonia, iron, manganese, trace metals

Industrial wastes VOCs, trace metals

Agricultural Pesticides, elevated nutrients (nitrate, phosphate)

Roads Chloride, sodium

Residential with on-site wastewater disposal Elevated nutrients (nitrate, phosphate), VOCs, boron, chloride, organic wastewater compounds
Introduction 5

Figure 2. Land use in 2000 in Chester County, Pa., and location of selected parks and other county-owned land.

Impounding basins

for Schuylkill River sediments

76° 75°50' 75°40' 75°30'

39°40'

39°50'

40°

40°10'

0 5 10 MILES

0 8 16 KILOMETERS

EXPLANATION

Agricultural

Commercial

Residential

Transportation, utility

Parking

Mining

Manufacturing

Recreation, vacant

Wooded

Water

Land use

Warwick Park

Hibernia Park (and dam)

Nottingham Park

Exton Park

(former Church Farm School land)
6 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

(Senior, 1996), microbiological quality (Lindsey and others, 

2002), and effects of spray irrigation (Schreffler and others, 

2005). USGS reports by Sloto (1997, 2001) describe aspects 

of groundwater contamination related to two Superfund sites 

in Chester County.

Well, Spring, and Stream Identification System

Each well and spring is identified by a local number 

(or name) and a 15-digit station identification number that is 

based on the latitude and longitude. In the text of the report, 

wells and springs are referred to by their local number, 

which consists of a county-abbreviation prefix followed by a 

sequentially assigned number. The prefix CH denotes a well 

and CH-SP denotes a spring in Chester County. In the appendix, sampled wells and springs are listed by the local number 

and the 15-digit station identification number. A few surfacewater sites are also identified by a 15-digit station identification number.

Stream sites generally are identified by a station identification number assigned in downstream order, typically eight 

or more digits in length and which is explained in more detail 

in Durlin and Schaffstall (1999) for example. The stream site 

name gives the name of the stream and nearby named geographic features such as a road or town.

Chester County Groundwater-Quality 

Monitoring Program

The Chester County groundwater-quality monitoring 

program consists of the annual collection of groundwater 

and occasional stream base-flow samples at various sites 

selected each year to assess potential risks to human health or 

other environmental concerns. Sample locations and analyses are selected by USGS in consultation with the CCWRA 

and CCHD to meet one or more of the following objectives: (1) to provide data on groundwater quality near suspected sources of contamination; (2) to provide data that could 

be used to assess effects of land-use activities on groundwater 

and stream base-flow quality; (3) to provide data on naturally 

occurring constituents in groundwater that may pose a health 

risk; and (4) to informally monitor changes in groundwater 

quality near known sources of contamination.

The monitoring program was initially driven by interest in obtaining data on groundwater quality near suspected 

point sources of contamination, such as uncontrolled landfills (dumps) and industrial on-site waste discharges. Later, 

especially after 1985, the program evolved to investigate 

the effects of other land-use activities on groundwater and 

base-flow quality and the distribution of naturally occurring 

constituents that may be harmful to human health, such as 

arsenic, radium, and radon. The number of samples collected each year and the type of source targeted for sample 

collection are listed in table 2. A detailed listing and locations of wells, springs, or streams (base-flow sites) sampled 

each year from 1980 through 2008 are given in appendix 1. 

The sample locations also may be obtained through the web 

interface http://nwis.waterdata.usgs.gov/pa/nwis/qwdata by 

searching by county and the site number (station number) 

listed in appendix 1 and then selecting site map from list of 

available data for the site. The locations of all stream sites 

and wells with hydrologic data, including water-quality data, 

in Pennsylvania may be obtained through the web interface 

http://wdr.water.usgs.gov/nwisgmap/?state=pa.

The focus of the groundwater-monitoring program was 

a spatial rather than temporal assessment of groundwater 

quality. However, groundwater quality can change through 

time because of (1) changes in land use and sources at the 

land surface, recharge, and groundwater-flow directions, or 

(2) transport and chemical reactions in the aquifer. Changes 

in groundwater quality may result in constituent concentrations that exceed water-quality standards and therefore pose 

increased risks to human health or have other adverse effects 

on non-consumptive water use. Some variability in groundwater quality may be seasonal if related to the natural hydrologic 

cycle; other variability may show a trend reflecting long-term 

changes in land use.

Although most samples were collected to determine the 

location and extent of possible groundwater-quality problems 

in the county, a few wells were sampled more than once to 

provide data on groundwater quality through time. Some wells 

were resampled periodically over a few years to evaluate 

persistence of contaminants or, on regular intervals for 2 years 

in the radon study (Senior, 1998), to evaluate seasonal fluctuations. Wells resampled for different assessments occasionally 

yielded data on concentrations of selected constituents at various time intervals.

Base-flow samples were collected for the monitoring 

program in small or headwater streams to provide data on the 

relation between the quality of groundwater and surface water. 

Groundwater discharge to streams is the source of stream base 

flow. Some constituents dissolved in groundwater, especially 

relatively soluble constituents that are not adsorbed onto soils 

or aquifer materials or readily degraded in the groundwater 

system, may be transported in groundwater and discharge to 

streams in the drainage area.

Sampling needs for the monitoring program typically 

were defined in the spring of each year, and sites are sampled 

the following summer. The number of sites sampled each year 

has ranged from 6 to 61, depending on the need and the costs 

of sample collection and analysis. No samples were collected 

in 2004. The USGS collected samples mostly from domestic 

wells but also from non-domestic production wells and a few 

springs. Samples were collected using standard techniques 

(U.S. Geological Survey, variously dated) and analyzed by the 

USGS National Water Quality Laboratory (NWQL) for most 

constituents. For some constituents, such as formaldehyde 

and most radiochemicals, laboratories under contract to the 

NWQL performed the analyses. All NWQL water-quality data 
Chester County Groundwater-Quality Monitoring Program 

7

Table 2. Number and type of sites sampled and reason for sample collection listed by possible contaminant source for the Chester County groundwater-monitoring program, 1980-2008.—Continued

Year

Number of sites

by year

Wells or surface-water sites by possible

contaminant source

Remarks on land use and natural sources

Wells

Surfacewater

sites

Landfill1 Industrial waste2 Other land use3 Natural4

1980 18 17 11981 46 17 291982 42 10 30 2 Nursery, turf farm1983 40 9 21 10 Pesticides in rights-of-way, orchards; salt storage area near highway1984 38 1 7 30 2 Pesticides in rights-of-way, golf course;1985 51 7 3 43 4 8 Deicing salt near highway; radium in quartzite aquifers1986 51 5 13 5 28 Spray irrigation of wastewater; radiochemistry in geologic units countywide1987 60 10 18 3 29 Agricultural areas; radiochemistry in northern Chester County Triassic-rock aquifers1988 49 10 14 19 6 Agriculture (pesticides and nitrate) in Red Clay Creek Basin; baseline pre-spray irrigation or 

septic system; radiochemistry in limestone aquifers

1989 42 13 6 23 Agriculture (pesticides and nitrate) in Red Clay Creek Basin; proposed park area (Church 

Farm School)

1990 36 3 11 7 15 White Clay Creek headwater area, pesticides and nitrate in Red Clay Creek Basin; radon 

throughout county

1991 35 1 13 10 11 Agriculture (pesticides and nitrate) in Red and White Clay Creek Basins; cemeteries; Church 

Farm School area; radon throughout county

1992 30 2 10 10 8 Agriculture (pesticides and nitrate) in White Clay Creek Basin; compare areas with sewer to 

areas with septic systems; radon throughout county

1993 32 7 19 5 1 Near composting operations; radon (also Schuylkill impounding basins as landfill)1994 29 6 8 15 County parks; Hibernia area before dam; Red Clay Creek pesticide resampling; (also, 

Schuylkill impounding basins as landfills)

1995 32 7 3 22 Areas with septic systems used since 1970s; County park; baseline pre-spray irrigation; 

(also, Schuylkill impounding basins as landfill)

1996 28 4 3 15 6 Sand filter systems for on-site wastewater disposal; cemeteries; upstream of groundwater 

supplies; baseline pre-golf course development; near compost operation; serpentine barren; deicing salt near highway; temporal radon

1997 19 1 2 11 5 Agriculture (pesticides and nitrate) in White Clay Creek Basin; cemetery; large on-site 

wastewater disposal systems; land application of sludge; temporal radon

1998 7 3 4 Land-use areas for Christina River Basin study1999 14 2 12 Radium-224 (14 total radium-224 sites because 2 wells near landfill also tested for radium-224)
8 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008 Table 2. Number and type of sites sampled and reason for sample collection listed by possible contaminant source for the Chester County groundwater-monitoring program, 1980-2008.—Continued Year Number of sites by year Wells or surface-water sites by possible contaminant source Remarks on land use and natural sources Wells Surface- water sites Landfill1 Industrial waste2 Other land use3 Natural4 2000 43 7 2 41 Pesticides and nitrate in Octoraro Creek basin groundwater and base flow; on-site wastewa- ter disposal including emerging contaminants 2001 21 21 Various land uses in areas of county not sampled before 2002 6 6 Spray irrigation and drip disposal of wastewater 2003 17 17 Lead, lead-210, radon, and other radioactivity in Chickies Quartzite 2004 0 No samples collected in 2004, review of lead data 2005 10 10 20 Agicultural and residential land uses with sewers or on-site wastewater disposal in Broad Run Basin (groundwater and base flow) 2006 30 30 Lead, including resampling of wells with previously detected lead 2007 2 15 17 Baseline pre-residential development near Beaver Creek Dam (base flow, dam, and ground- water) and base-flow reference sites in nearby basins 2008 5 5 10 Residential on-site wastewater disposal (groundwater and base flow) Total 833 45 134 271 312 146

1Uncontrolled landfills, including dumps, and other waste-disposal locations.2Uncontrolled localized industrial or commercial on-site waste releases.3Other land uses include residential, agricultural, wooded, transportation, and open.4Inorganic constituents primarily derived from rocks and soils.
Chester County Groundwater-Quality Monitoring Program 9

are stored in USGS databases and are available to the public 

(http://nwis.waterdata.usgs.gov/pa/nwis/qwdata).

The types of analyses performed on the water samples 

were selected to target suspected contaminants or other constituents of interest. In addition, especially after 1988, samples 

commonly also were analyzed for major ions, such as calcium, 

sodium, and chloride, and basic nutrients, such as nitrate 

and phosphate, to provide information about general water 

quality and the distribution of these constituents countywide. 

Selected groundwater samples from 1986 through 1988 and 

most groundwater samples from 1989 through 2003 were 

analyzed for radon-222, a radioactive gas that is the product of 

radium-226 decay in the uranium-238 decay chain.

Only one or two quality control (QC) samples were collected each year as part of the monitoring program because of 

the limited annual funding and scope of the program (being 

reconnaissance in nature). Most samples collected for QC 

purposes were environmental replicates, and these data are 

available in the USGS databases for review. Replicates typically were assigned a sample time that is 1 minute apart. For 

analyses of the organic wastewater compounds and pharmaceuticals in 2008 that are reported in parts per trillion, the QC 

sample consisted of a blank in which no compounds were 

detected. In general, few QC problems were identified with the 

limited QC.

This report briefly summarizes results of the monitoring program only from 1980 through 2008 and, in contrast to previous reports, is organized by potential sources 

of contaminants or constituents. These sources are either 

natural or related to human activities, such as agricultural, 

commercial, industrial, and residential development, and 

waste disposal, all of which have the potential to affect 

groundwater quality. Localized activities, such as landfills or 

industrial waste disposal, may affect groundwater quality only 

nearby or in some cases, such as in the carbonate aquifers, 

may be transported thousands of feet from the contaminant 

source. More widely spatially distributed activities, such as 

residential or agricultural land uses, may affect groundwater 

quality over large areas. Results of the monitoring program 

that have not been discussed in previous reports, including 

data collected from 2001 through 2008, are presented in greatest detail in this report.

Results of Sampling for Constituents Associated 

with Land Uses and Human Activities

Results of sampling in targeted areas showed that contaminants associated with various sources commonly were 

detected in groundwater and sometimes in base flow near 

those sources. The results for contaminants and constituents 

detected in the targeted areas are summarized for each type of 

source in the following sections.

Contaminants, where detected, were present at trace 

levels to concentrations that exceeded maximum contaminant 

levels (MCLs), health advisories (HAs), or other values such 

as drinking-water equivalent levels (DWELs) listed by the 

U.S. Environmental Protection Agency (USEPA) to protect 

human health for those constituents in drinking water (U.S. 

Environmental Protection Agency, 2009a). Many compounds 

or constituents that may be present in groundwater do not have 

established MCLs, which are regulatory primary drinkingwater standards, but may pose a risk to human health in 

drinking water, and USEPA lists other non-regulatory levels, 

such as HAs and DWELs, for some of these compounds and 

constituents. The MCLs and HAs for selected constituents 

commonly detected in groundwater in Chester County are 

listed in table 3.

The MCLs established by the USEPA are required for 

public drinking-water supplies but may be used as guidelines 

for private well owners whose water generally is not regulated 

in Pennsylvania. However, for private well owners in Chester 

County, the CCHD does require that tap water from new wells 

meet turbidity, nitrate, and bacteria standards for public health 

protection. Secondary maximum contaminant levels (SMCLs) 

established by the USEPA are other non-regulatory guidelines 

established for aesthetic reasons such as taste and odor (U.S. 

Environmental Protection Agency, 2009a).

Uncontrolled Landfills, Dumps, and Industrial 

Waste Discharges

Groundwater sampling near uncontrolled landfills, 

dumps, and industrial waste discharge areas occurred primarily during the first 10 years of the monitoring program and 

tapered off during the next 10 years after many of the sources 

of uncontrolled contaminants were identified. From 1980 

through 1989, 82 samples were collected near uncontrolled 

landfills and dumps, and 172 samples were collected near 

industries. From 1990 through 2000, a total of 105 samples 

was collected near uncontrolled landfills or industries, and 

after 2000, no samples were collected near those types of 

sources. Samples near uncontrolled landfills or industries 

were analyzed for selected metals; one or more types of 

anthropogenic organic compounds, including VOCs such as 

trichloroethylene (TCE) and tetrachloroethylene (PCE); acidextractable compounds, such as phenol; gross phenols; baseneutral-extractable organic compounds, such as napthalene; 

polychlorinated biphenyls (PCBs); polychlorinated napthalenes (PCNs); and (or) organochlorine insecticides, such as 

dichlorodiphenyltrichloroethane (DDT).

Locations sampled during the first 10 years of the program generally showed higher levels of groundwater contamination by solvents, such as TCE and PCE, than those sampled 

after 1990 because of differences in the areas targeted for 

sampling. Of the VOCs analyzed from 1980 through 2001, 

TCE was the most frequently detected, with concentrations 

up to 4,400 μg/L. Concentrations greater than 100 μg/L were 

measured in samples collected from 15 wells during 1980–89 

(Sloto, 1989, 1994). In contrast, the greatest TCE concentration measured in samples collected during 1990–2001 was 
10 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Table 3. Maximum contaminant levels, health advisories, and secondary maximum contaminant levels established by the U.S. 

Environmental Protection Agency (2009) for selected constituents in drinking water.—Continued

[MCL, maximum contaminant level; HA, lifetime health advisory, unless noted; SMCL, secondary maximum contaminant level; μg/L, micrograms per liter; 

mg/L, milligrams per liter; mg/L as N, milligrams per liter as nitrgen; pCi/L, picocuries per liter; mrem/yr, millirem per year; DWEL, drinking-water equivalent level; --, no standard]

Compounds Units MCL HA SMCL Remarks

Industrial compound/solvents

1,1-dichloroethylene μg/L 7 2,000 -- DWEL HA, 10-4 cancer risk is 6 μg/L

1,1,1-trichloroethane μg/L 200 70,000 -- DWEL HA

Formaldehyde mg/L -- 1 --

Napthalene μg/L -- 100 --

PCBs μg/L .5 -- -- 10-4 cancer risk is 10 μg/L

Phenol mg/L -- 2 --

Tetrachloroethylene μg/L 5 10 --

Trichloroethylene μg/L 5 200 -- DWEL HA

Trihalomethanes (total)1 μg/L 80 70 --

Pesticides

Alachlor μg/L 2 400 -- DWEL HA, 10-4 cancer risk is 4 μg/L

Atrazine μg/L 3 700 -- DWEL HA

Ametryn μg/L -- 60 --

Carbaryl μg/L -- 400 -- DWEL HA

Carbofuran μg/L 40 -- --

Chlordane μg/L 2 20 -- DWEL HA, 10-4 cancer risk is 10 μg/L

Diazinon μg/L -- 1 --

Dieldrin μg/L -- 2 -- DWEL HA, 10-4 cancer risk is 0.2 μg/L

Lindane μg/L .2 200 -- DWEL HA

Malathion μg/L -- 500 --

Methoxychlor μg/L 40 40 --

Metolachlor μg/L -- 700 --

Prometon μg/L -- 400 --

Propazine μg/L -- 100 --

Silvex (2,4,5-TP) μg/L 50 50 --

Simazine μg/L 4 700 -- DWEL HA

Tebuthiuron μg/L -- 500 --

Terbacil μg/L -- 90 --

Trifluralin μg/L -- 10 --

Metals and inorganics

Arsenic μg/L 10 2 -- 10-4 cancer risk for HA

Boron μg/L -- 6,000 --

Cadmium μg/L 5 5 --

Chloride mg/L -- -- 250

Chromium (total) μg/L 100 100 -- DWEL HA

Cyanide μg/L 200 200 --

Iron μg/L -- -- 300

Lead μg/L 215 -- --

Manganese μg/L -- 300 50
Chester County Groundwater-Quality Monitoring Program 11

Table 3. Maximum contaminant levels, health advisories, and secondary maximum contaminant levels established by the U.S. 

Environmental Protection Agency (2009) for selected constituents in drinking water.—Continued

[MCL, maximum contaminant level; HA, lifetime health advisory, unless noted; SMCL, secondary maximum contaminant level; μg/L, micrograms per liter; 

mg/L, milligrams per liter; mg/L as N, milligrams per liter as nitrgen; pCi/L, picocuries per liter; mrem/yr, millirem per year; DWEL, drinking-water equivalent level; --, no standard]

Compounds Units MCL HA SMCL Remarks

Metals and inorganics—Continued

Mercury (inorganic) μg/L 2 2 --

Molybdenum μg/L -- 40 --

Nickel μg/L -- 100 --

Nitrate (as nitrogen) mg/L as N 10 -- --

Nitrite (as nitrogen) mg/L as N 1 -- --

Silver μg/L -- 100 100

Zinc μg/L -- 2,000 5,000

Radionuclides

Gross beta-particle and photon activity mrem/yr 4 -- --

Gross alpha-particle activity pCi/L 15 -- --

Radium-226 and radium-2283 pCi/L 5 -- --

Radon-222 pCi/L 4300 -- -- 10-4 cancer risk is 150 pCi/L

Uranium μg/L 30 -- --

1

Includes chloroform (trichloromethane).

2

Action level.

3

Combined radium-226 and radium-228.

4

Proposed; proposed alternate MCL 4,000 pCi/L.

95 μg/L (Ludlow and Loper, 2004). Samples from 32 (14 

percent) of 225 wells sampled before 1990 had concentrations of TCE that were greater than the MCL of 5 μg/L (Sloto, 

1994), whereas samples from only 2 percent of 187 wells 

sampled from 1990 through 2001 (Ludlow and Loper, 2004) 

had concentrations of TCE greater than 5 μg/L. Overall from 

1980 through 2008, TCE concentrations greater than the MCL 

of 5 μg/L were measured in samples from 47 wells. Concentrations of other detected VOCs, including PCE, 1,1,1-trichloroethane (TCA), 1,1-dichloroethylene (DCE), 1,2-dichloroethane (DCA), benzene, carbon tetrachloride, and styrene, 

exceeded USEPA MCLs in 1 to 4 percent of samples collected 

before 1990 but in less than 1 percent of samples collected 

from 1990 through 2001.

During the 1980s to early 1990s, when the focus of the 

groundwater-quality monitoring program was on discrete 

localized sources such as landfills, dumps, and industrial waste 

activities, 27 wells were sampled for VOCs two or more times 

over several years to verify continued presence of detected 

contaminants (table 4). Concentrations of detected VOCs were 

similar in samples from some wells (such as CH-2136 and 

CH-3589), increased over time in some wells (CH-2403 and 

CH-2406), and decreased over time in some wells (CH-2448, 

CH-2449, and CH-2676). Variability in VOC concentrations 

is common near sources of contamination and may result in 

variable exceedances of drinking-water MCLs. For example, 

in samples collected from well CH-2406 in 1980, concentrations of PCE and TCE were less than the MCLs of 5 μg/L for 

those compounds but were considerably greater than 5 μg/L in 

1981. These temporal VOC data show that results of a single 

sample cannot be used to represent water quality through time, 

especially if changes in sources, groundwater-flow directions, 

or other factors that affect groundwater quality are likely.

The elevated concentrations of anthropogenic organic 

compounds measured in wells sampled in the 1980s were 

used to help identify sites that eventually were placed on the 

USEPA National Priority List (NPL) to be remediated under 

CERCLA (Superfund) (fig. 3). Of the 11 sites placed on the 

NPL in Chester County, 9 were proposed for listing before 

1990 on the basis of sampling results from the monitoring program (fig. 3). Samples collected through the monitoring program also helped to identify other areas of contamination that 

currently are being addressed by USEPA under the Resource 

Conservation and Recovery Act (RCRA) or by the Pennsylvania Department of Environmental Protection (PADEP). As 

of 2008, there were 15 RCRA sites in Chester County (U.S. 

Environmental Protection Agency, 2009b) (fig. 3).
12 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008 Table 4. Concentrations of volatile organic compounds detected in wells sampled more than once, Chester County, Pa.—Continued [Analyte parameter codes in parentheses; column blank if compound not detected in any sample from well; --, compound not included in analysis; 111TCA, 1,1,1-trichloroethane; 11DCA, 1,1-dichloroeth- ane; 11DCE, 1,1-dichloroethylene; 12DCA, 1,2-dichloroethane; CHBr Cl, dibromochloromethane; DCM, dichloromethane; cis12DCE, 1,2-dichloroethylene; PC 2 E, tetrachloroethylene; trans12DCE, trans- 1,2-dichloroethylene; TCE, trichloroethylene; CFC-11, trichlorofluoromethane; CHCl3, trichloromethane; <, less than] U.S. Geo- logical Survey local well number Date sampled Volatile organic compound detected at least once, concentration in micrograms per liter 111TCA (34506) 11DCA (34496) 11DCE (34501) 12DCA (32103) Benzene (34030) CHBr Cl 

2

(32105)

DCM 

(34423)

cis12DCE 

(77093)

PCE 

(34475)

Toluene 

(34301)

trans 

12DCE 

(34546)

TCE 

(39180)

CFC-11 

(34488)

CHCl3

(32106)

CH-31 7/7/1983 -- 400 8CH-31 5/16/1984 -- 290 5CH-69 5/7/1981 -- 1CH-69 5/16/1984 -- 0CH-207 8/27/1984 -- 7 0 18CH-207 6/18/1985 -- <3 4 12CH-307 6/2/1981 9 --CH-307 7/16/1991 < .2 --CH-1978 8/30/1984 -- <3CH-1978 6/30/1993 .6CH-2046 5/29/1981 60 0 20 -- 30 500 540CH-2046 6/27/1983 69 62 16 -- 10 520 700CH-2136 8/19/1981 <1 -- 200CH-2136 6/22/1982 3 -- 220CH-2348 6/11/1980 60 -- 150CH-2348 5/7/1981 0 -- 0CH-2348 6/24/1988 <3 -- <3CH-2402 6/3/1980 -- 0 0CH-2402 6/7/1994 0.9 .9 .4CH-2403 6/4/1980 0 0 --CH-2403 8/5/1985 <3 7 --CH-2403 8/8/1986 8 7 --CH-2406 6/11/1980 8 -- 0 4CH-2406 8/18/1981 130 -- 10 1,060CH-2411 8/26/1980 -- 9 8 0CH-2411 8/18/1981 -- 20 <1 <1CH-2411 7/22/1982 -- <1 <1 <1CH-2411 8/22/1989 -- <3 <3 23CH-2412 8/26/1980 0 --CH-2412 6/24/1982 4 --
Chester County Groundwater-Quality Monitoring Program 13

Table 4. Concentrations of volatile organic compounds detected in wells sampled more than once, Chester County, Pa.—Continued[Analyte parameter codes in parentheses; column blank if compound not detected in any sample from well; --, compound not included in analysis; 111TCA, 1,1,1-trichloroethane; 11DCA, 1,1-dichloroethane; 11DCE, 1,1-dichloroethylene; 12DCA, 1,2-dichloroethane; CHBr Cl, dibromochloromethane; DCM, dichloromethane; cis12DCE, 1,2-dichloroethylene; PC 2 E, tetrachloroethylene; trans12DCE, trans1,2-dichloroethylene; TCE, trichloroethylene; CFC-11, trichlorofluoromethane; CHCl3, trichloromethane; <, less than]

U.S. Geological 

Survey 

local 

well 

number

Date 

sampled

Volatile organic compound detected at least once, concentration in micrograms per liter

111TCA 

(34506)

11DCA 

(34496)

11DCE 

(34501)

12DCA 

(32103)

Benzene 

(34030)

CHBr Cl 2

(32105)

DCM 

(34423)

cis12DCE 

(77093)

PCE 

(34475)

Toluene 

(34301)

trans 

12DCE 

(34546)

TCE 

(39180)

CFC-11 

(34488)

CHCl3

(32106)

CH-2414 8/26/1980 -- 7CH-2414 5/7/1981 -- 0CH-2415 8/29/1980 0 -- 0 0CH-2415 7/9/1986 4 -- 3 83CH-2429 5/29/1981 0 -- 0 0 0CH-2429 7/2/1984 <3 -- 7 4 8CH-2429 8/22/1985 6 -- <3 <3 40CH-2429 7/29/1986 <3 -- <3 <3 <3CH-2443 10/21/1981 <1 --CH-2443 8/3/1982 <1 --CH-2443 6/1/1988 5 --CH-2444 8/18/1981 180 <1 --CH-2444 8/3/1982 <1 <1 --CH-2444 9/3/1985 50 11 --CH-2448 8/21/1981 -- 30CH-2448 7/9/1982 -- 26CH-2448 8/24/1987 -- 3CH-2449 8/21/1981 20 200 -- 20 50CH-2449 6/23/1982 <1 <1 -- <1 <1CH-2476 7/20/1982 <1 --CH-2476 9/4/1985 6 --CH-2478 8/3/1982 31 -- <1 22CH-2478 7/7/1983 7 -- 10 34CH-2505 7/14/1983 220 2,900 <1 1,500 --CH-2505 7/11/1986 260 1,100 1,200 <15 --CH-2569 4/30/1985 -- <3CH-2569 7/25/1987 -- 9CH-2676 6/7/1984 -- 210 470CH-2676 5/27/1988 -- 3 240CH-2676 8/17/1995 11 < .2 .4CH-3589 7/15/1993 .4 .6 6.2 4.7CH-3589 7/27/1995 .2 .7 12 4.2
14 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Figure 3. National Priority List (Superfund) and Resource Conservation and Recovery Act (RCRA) sites in Chester County, Pa., 

and locations of wells sampled through the Chester County groundwater-quality monitoring program that had detections of volatile 

organic compounds.

76° 75°50' 75°40' 75°30'

40°10'

40°

39°50'

39°40'

0 5 10 MILES

0 8 16 KILOMETERS

EXPLANATION

Volatile organic compound

concentration in well water

Not detected

Less than MCL

Contaminant site type

RCRA

Superfund site

(year listed on NPL)

Municipality

Greater than MCL

Walsh Landfill (1984)

William Dick Lagoons (1987)

Blosenski Landfill (1983)

Old Wilmington Road (2000)

Strasburg Landfill (1989)

Kimberton (1983)

Recticon/Allied Steel (1989)

Paoli Railyard (1990)

Malvern TCE (1983)

Foote Mineral (1992)

AIW Frank (1989)
Chester County Groundwater-Quality Monitoring Program 15

Concentrations of ammonia elevated above background 

level and up to 4.5 mg/L as N (well CH-2679) were measured 

in groundwater near some landfill and dump sites in Chester 

County. Elevated concentrations of ammonia were measured 

in groundwater samples collected in 1980–1982, 1984, 1987, 

and 1989 as part of the Chester County groundwater-quality 

monitoring program near where Pennsylvania State Route 29 

crosses Valley Creek and Little Valley Creek in East Whiteland 

Township (fig. 4). Ammonia concentrations up to 2.5 mg/L as 

N were measured in groundwater (well CH-2411) near Valley 

Creek and up to 4.4 mg/L as N were measured in groundwater 

(well CH-2448) near Little Valley Creek. Groundwater from 

well CH-2448 also had elevated nitrite concentrations up to 

1.6 mg/L as N and other contaminants such as cyanide up to 

0.06 mg/L and TCE up to 30 μg/L that probably were associated with nearby releases of industrial waste.

In 1998, as part of an informal investigation of possible 

limitations to trout migration and stable in-stream populations, elevated concentrations of ammonia (up to 1.39 mg/L 

as N) were measured by USGS (Durlin and Schaffstall, 1999, 

p. 351) in gaining reaches of Valley Creek near Route 29 

near where elevated ammonia had been detected in groundwater (fig. 4). Ammonia concentrations in Little Valley 

Creek were not determined. The groundwater-quality data 

support the inference that the elevated ammonia concentrations in the Valley Creek probably are related to discharge of 

groundwater containing elevated ammonia. An old landfill 

near Valley Creek and industrial activities near Little Valley 

Creek are most likely the sources of elevated ammonia in the 

groundwater and, thus, are the likely sources of ammonia to 

nearby streams through groundwater discharge in gaining 

stream reaches.

Other inorganic constituents associated with localized, 

industrial-waste sources included elevated concentrations of 

aluminum, nickel, cobalt, and manganese in samples from a 

well (CH-1074) near a metals processing facility near Atglen. 

In addition, groundwater samples collected as part of the 

monitoring program helped identify the transport of lithium 

and boron from a former metals processing plant in Frazer 

(now the Foote Mineral Superfund site) in both surface water 

and groundwater (figs. 3 and 4). The Foote Mineral site is on 

a groundwater and surface-water divide and is underlain by 

carbonate rocks. Lithium and boron wastes were disposed of 

in a former quarry on the eastern part of the site and also to a 

stream that flows west. Lithium and boron are trace elements 

that are relatively soluble in water and can be considered 

conservative tracers in groundwater flow because they are not 

readily degraded or adsorbed onto aquifer materials. Elevated 

concentrations of lithium and boron in well-water samples 

indicated that contaminated groundwater traveled eastward 

from the site, and stream samples showed that the contaminated groundwater also discharged into gaining reaches of 

Valley Creek, a tributary that flows east to the Schuylkill River 

(Sloto, 1987). Lithium and boron discharged in wastewater at 

the site to the stream flowing west was detected in groundwater west of the site in the West Valley Creek Basin, a tributary 

Other contaminants detected in groundwater samples 

during the first 10 years of the program included base-neutralextractable organic compounds such as napthalene and diethyl 

phthalate, gross phenols, and elevated concentrations of some 

metals, such as mercury (Sloto, 1989, 1994) and other inorganic constituents. Most of these constituents, except for gross 

phenols, were detected infrequently and were only measured 

near suspected localized contaminant sources. Some phenols occur naturally, and gross phenol analysis includes both 

natural and anthropogenic compounds. The USEPA has not 

established a MCL for phenol but lists a HA level of 2 mg/L 

for lifetime consumption of phenol (table 3). Of the 233 wells 

sampled for gross phenols, about 18 percent (42 of 233 wells) 

had concentrations of gross phenol greater than 2 μg/L in at 

least 1 sample, and about 5 percent (11 of 233 wells) had concentrations of gross phenol greater than 5 μg/L. Samples from 

only two wells had more than 25 μg/L gross phenols (up to 30 

and 190 μg/L in wells CH-3133 and CH-2419, respectively). 

No samples had concentrations of gross phenols that exceeded 

the HA of 2 mg/L.

Elevated concentrations of the inorganic constituents 

iron, manganese, and ammonia were measured in groundwater and some stream base-flow samples collected as part 

of the monitoring program. Elevated concentrations of iron, 

manganese, and ammonia may be related to reducing conditions (geochemical processes) that release naturally occurring metals and may be associated with the presence of some 

man-made organic contaminants, although natural processes 

can also release iron and manganese into groundwater. Generally, iron, manganese, and ammonia have been identified as 

the primary inorganic contaminants in groundwater associated with landfills (Deutsch, 1998). Ammonia and nitrite are 

chemically reduced forms of nitrogen that commonly convert 

to nitrate in oxygenated surface waters (Hem, 1985, p. 126). 

Concentrations of ammonia and nitrite generally are low (less 

than 0.05 and 0.01 mg/L as nitrogen (N), respectively) in 

groundwater and surface water not affected by human activities in Chester County.

Concentrations of dissolved iron and manganese greater 

than SMCLs of 300 and 50 μg/L, respectively, in some 

groundwater samples collected near uncontrolled landfills, 

dumps, and industrial waste disposal areas were the highest 

measured in groundwater in the county. Concentrations of 

iron up to 85,000 μg/L were measured in a sample from a well 

(CH-2473) near a landfill in Honeybrook Township in 1982. 

Samples from three other wells (CH-2406, CH-3624, and 

CH-2419) near landfills had extremely elevated iron concentrations ranging from 22,000 to 80,000 μg/L. Samples from 

these four wells also had high concentrations of manganese 

that ranged from 2,500 to 22,000 μg/L. These manganese concentrations exceed not only the SMCL but the HA of 300 μg/L 

listed by USEPA to protect human health (table 3). Additional 

study would be needed to evaluate all causes, some of which 

may be natural, of elevated concentrations of iron and manganese greater than the SMCLs that commonly occur in groundwater throughout Chester County.
16 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Figure 4. Location of base-flow samples collected as part of the Chester County groundwater-quality monitoring program 

and selected other areas of base-flow sampling, 1966 through 2008, Chester County, Pa.

76° 75°45' 75°30'

40°15'

40°

39°45'

Area with elevated ammonia

in groundwater and base flow

in Valley Creek near Route 29

Foote Mineral Site source 

of lithium and boron in 

baseflow and groundwater

0 2 4 8 MILES

0 3 6 12 KILOMETERS

EXPLANATION

Red Clay Creek Basin

White Clay Creek Basin

01480903

Stream site and identification number

for long-term base-flow monitoring

Well sampled in 2007

Well sampled in 2008

Base flow sampled in 2007

Base flow sampled in 2008

Area of residential land use

Octoraro Creek Basin, sampled 2000

Broad Run Basin, sampled 2005

Beaver Creek Basin, sampled 2007

01480903

01479680

01472190

01472080

01472157

01480653

01479800
Chester County Groundwater-Quality Monitoring Program 17

to the Brandywine Creek, probably having entered the 

groundwater through losing reaches of the stream (Senior and 

others, 1997). Lithium and boron measurements in groundwater and surface water showed the interconnections between the 

groundwater and surface-water systems and the pathways of 

contaminant transport from the source area.

Agricultural Use of Pesticides and Nitrate

Pesticides (most commonly herbicides and insecticides) 

and fertilizer applied at the land surface for agricultural and 

other land uses have the potential to leach into the groundwater system. In Chester County, such constituents have been 

used in a range of agricultural activities, including the cultivation of row crops, mushrooms, orchards, and nurseries, and 

non-agricultural activities, including golf courses, vegetation 

control on transportation rights-of-way, and residential and 

commercial landscaped areas. The use of these constituents 

sometimes results in the occurrence of low levels of pesticides or elevated levels of nutrients (especially nitrate) in 

groundwater.

Concentrations of nitrate greater than the estimated 

natural background concentration of about 1 mg/L as N and 

all detections of pesticides or herbicides in groundwater 

are related to human land-use activities in Chester County. 

Drinking-water standards or MCLs have been established by 

USEPA for nitrate (10 mg/L as N) and nitrite (1 mg/L as N) 

but for only some pesticides (U.S. Environmental Protection 

Agency, 2009a; table 3).

Countywide Investigations

Before 1988, few wells in Chester County were sampled 

for pesticides. From 1988 through 1997, about 95 groundwater 

samples were collected mostly near agricultural areas such as 

orchards, mushroom houses and composting operations, and 

land in row-crop cultivation. A few samples were collected in 

other areas that may be associated with the use of pesticides 

and fertilizer, such as transportation rights-of-way and residential areas. Analyses included organochlorine or organophosphate insecticides, herbicides, and the fertilizer nutrients 

nitrate and phosphate. Many of the wells sampled were in 

agricultural areas in southern Chester County, especially the 

Red Clay Creek and White Clay Creek watersheds. These 

watersheds have diverse types of agriculture, including many 

mushroom farms and compost operations.

Low concentrations of the herbicides atrazine, 2-chloro4-isopropylamino-6-amino-s-triazine (CIAT), metolachlor, 

and prometon and the insecticides chlordane, diazinon, DDT, 

dichlorodiphenyldichloroethylene (DDE), lindane, malathion, 

methoxychlor, and phorate were detected in groundwater 

in the Red Clay and White Clay Creek watersheds. Some 

pesticides were measured at levels that may pose health risks. 

Lindane concentrations greater than the USEPA MCL of 

0.2 μg/L were measured in samples from two wells (0.34 μg/L 

in CH-4295 and as high as 25 μg/L in CH-4126) near a 

mushroom-growing area. Diazinon concentrations exceeded 

the USEPA lifetime HA level of 1 μg/L for diazinon in drinking water (table 3) in samples from two wells (2.6 μg/L in 

CH-69 and 490 μg/L in CH-4122).

In row-crop areas, the metolachlor concentration of 

12.6 μg/L in a well-water sample (CH-2311) was the highest concentration of analyzed herbicides in the county. The 

USEPA has not established a MCL for metolachlor but lists 

a lifetime HA level of 700 μg/L for metolachlor in drinking 

water (U.S. Environmental Protection Agency, 2009a; table 3). 

Other compounds detected in agricultural areas include atrazine and tebuthiuron. In nursery areas, pesticides detected in 

well-water samples (CH-30, CH-2461, and CH-5222) included 

the herbicides alachlor, CIAT, atrazine, s-ethyl dipropylthiocarbamate (EPTC), metolachlor, prometon, and trifluralin and 

insecticides carbaryl, carbofuran, dieldrin, lindane, and malathion; the concentration of 2.49 μg/L alachlor in one sample 

exceeded the MCL of 2 μg/L. The herbicides CIAT, simazine, 

and silvex were detected in well-water samples (CH-2503 and 

CH-5560) near orchards. Near a pipeline right-of-way, which 

is not an agricultural land use, the herbicides ametryn, atraton, 

atrazine, prometon, prometryn, propazine, simazine, simatone, 

and simatryn were detected at low concentrations (less than or 

equal 0.1 μg/L) in samples from one well (CH-206).

Results of sampling groundwater in the targeted areas 

showed that nitrate concentrations elevated above natural 

background (about 1 mg/L as N) were common, and concentrations as great as 45 mg/L as N were measured. About 

11 percent of the 543 wells sampled countywide through the 

groundwater-quality monitoring program had nitrate concentrations that equaled or exceeded the MCL of 10 mg/L as N, 

and more of these wells were in the southern part of the county 

than in the northern part of the county. About 17 percent of 

the 279 sampled wells in southern Chester County (south of 

40° latitude), where agricultural use is more prevalent than in 

northern Chester County (fig. 2), had nitrate concentrations 

equal to or greater than 10 mg/L as N. Only about 5 percent 

of the 264 wells in northern Chester County (north of 40° 

latitude) had nitrate concentrations equal to or greater than 

10 mg/L as N. Countywide, nitrite concentrations greater than 

the MCL of 1 mg/L as N were infrequent and were measured 

in samples from only two wells, one of which was in the Red 

Clay Creek watershed (CH-4730, appendix).

Detections of pesticides at low concentrations were common in many of the targeted areas, but concentrations above 

drinking-water standards, where established, were infrequent. 

The common occurrence of low concentrations of pesticides 

and elevated concentrations of nitrate is related to the effect of 

various agricultural activities on groundwater quality.

Octoraro Creek Investigation

To identify potential areas of elevated nitrate concentrations in the Octoraro Creek Basin (fig. 4) in western Chester 

County where agricultural land use is predominant (fig. 2), 

samples of groundwater and stream base flow were collected 
18 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

in 2000 (fig. 5) as part of the monitoring program. East Branch 

and mainstem Octoraro Creek form the boundary between 

Chester and Lancaster County (fig. 5) and are part of the 

Chesapeake Bay drainage system. The Octoraro Creek supplies a reservoir used for drinking water that has had elevated 

nitrate concentrations (Chester Water Authority, 2008). During 

a period of base-flow or low streamflow conditions, when 

groundwater discharge is the main source of streamflow, 

base-flow samples were collected near the confluence of seven 

tributaries with Octoraro Creek. Twenty-one wells within 

those tributary drainage areas also were sampled. All samples 

were analyzed for major ions, nutrients (nitrate and phosphate), selected trace elements, and selected pesticides, and 

results were published in Durlin and Schaffstall (2001b).

Concentrations of nitrate were greater than 7 mg/L as N 

in base flow of five of the seven tributaries, including Valley 

Creek, Leech Run, Muddy Run, and Tweed Creek, and were 

as high as 9.5 mg/L as N in Knight Run. The average nitrate 

concentrations in well-water samples in each tributary drainage area ranged from 7.1 to 10.8 mg/L as N and were similar 

to base-flow concentrations in most of those areas (fig. 5). The 

drainage areas with the lowest nitrate concentrations in base 

flow (3.5 to 4 mg/L as N in Black Run and Blackburn Run) 

also had some of the lowest nitrate concentrations in groundwater. Nitrate concentrations in groundwater ranged from 3.2 

to 14 mg/L as N; 6 of the 21 samples (29 percent) had nitrate 

concentrations greater than the MCL of 10 mg/L as N and 14 

of 21 samples (67 percent) had nitrate concentrations greater 

than 7 mg/L as N.

The pesticides atrazine, its degradation product deethyl 

atrazine, and metolachlor were the most frequently detected 

of the analyzed pesticides in both groundwater and base-flow 

samples. In groundwater samples from 21 wells, deethyl 

atrazine was detected most often (20 wells), followed by metolachlor (18 wells), and atrazine (13 wells). Atrazine, deethyl 

atrazine, and metolachlor were detected in samples from all 

seven base-flow sites. In groundwater and base-flow samples, 

the concentrations of deethyl atrazine were higher than its 

parent atrazine. Concentrations of deethyl atrazine ranged 

from 0.10 to 0.32 μg/L in base flow and 0.009 to 1.7 μg/L in 

groundwater. Atrazine concentrations ranged from 0.013 to 

0.081 μg/L in base flow and 0.009 to 0.353 μg/L in groundwater. The MCL for atrazine is 3 μg/L in drinking water (table 3). 

Herbicides, such as atrazine, in surface water can harm algae 

and other lower levels of the food chain in some aquatic environments and have been found to be persistent in tributaries to 

the Chesapeake Bay (McConnell and others, 2004).

More pesticides were detected in groundwater than 

in base flow. In addition to atrazine, deethyl atrazine, and 

metolachlor, 10 other pesticides were detected in groundwater: carbaryl (5 wells), simazine (4 wells), diazinon (3 wells), 

malathion (3 wells), prometon (3 wells), dieldrin (1 well), 

EPTC (1 well), tebuthiuron (1 well), terbacil (1 well), and 

trifluralin (1 well); three other pesticides were detected in base 

flow: alachlor (3 sites), tebuthiuron (2 sites), and prometon 

(1 site). Measured concentrations of these pesticides in the 21 

well-water samples did not exceed any established drinkingwater MCL, although not all pesticides analyzed and detected 

have established MCLs (table 3; U.S. Environmental Protection Agency, 2009a).

Results of sampling in Octoraro Creek tributary subbasins generally show a relation between constituent concentrations in groundwater and surface water (under base-flow 

conditions); areas with relatively high concentrations of nitrate 

and pesticides in groundwater also have high concentrations 

of those constituents in base flow. Concentrations of nitrate 

and pesticides, however, were more variable in groundwater 

samples than in base-flow samples within a drainage basin. 

Because groundwater supplies stream base flow, reducing 

nitrate loads to the groundwater system would be an important 

step in lowering the elevated nitrate concentrations in stream 

base flow and the drinking-water reservoir.

Deicing Salts on Highways and Salt Storage 

Areas

Use of salt for deicing roadways has the potential to 

affect groundwater quality near high-use roads and near salt 

storage areas. Salts used for deicing include sodium chloride 

and calcium chloride. These salts are very soluble and readily 

enter the groundwater system. Other human activities and land 

uses, such as on-site disposal of wastewater (septic systems), 

may also contribute chloride salts to groundwater. The estimated natural background concentration of chloride in groundwater in Chester County is about 10 mg/L or less (Senior and 

others, 1997). Ludlow and Loper (2004) reported that 50 percent of the 440 well samples analyzed for chloride from 1990 

to 2001 contained more than 13 mg/L, indicating that at least 

half of the wells in the county have chloride concentrations 

above natural background.

In 1983, 1985, and 1996, samples from a few wells near 

salt storage areas and highways were analyzed for chloride. Concentrations of chloride as high as 2,100 mg/L were 

measured in a sample from a well (CH-2478) at a salt storage area near the Pennsylvania Turnpike. Chloride concentrations greater than the SMCL of 250 mg/L for drinking 

water and as high as 350 mg/L were measured in a domestic 

well (CH-2574) near the Turnpike. Other similarly elevated 

chloride concentrations in groundwater near the Pennsylvania 

Turnpike were reported by Sloto (1987). Chloride concentrations greater than 250 mg/L are quite elevated in comparison 

to concentrations in most other well-water samples in the 

county. Ludlow and Loper (2004) reported that 75 percent 

of 440 well-water samples in the county had chloride concentrations of 28 mg/L or less. Water from 44 wells, or about 

4 percent of wells in the county with chloride data, had chloride concentrations greater than or equal to 100 mg/L, more 

than 10 times the natural background concentration.

Where chloride concentrations are elevated, concentrations of sodium and (or) calcium also are likely to be elevated 

because the most common source of elevated chloride is salt, 
Chester County Groundwater-Quality Monitoring Program 19

Figure 5. Nitrate concentrations in base-flow samples from 7 tributaries to Octoraro Creek and in groundwater 

samples from 21 wells in those tributary basins, Chester County, Pa., 2000. Location of Octoraro Creek shown on 

figure 4.

Tweed Creek

PENNSYLVANIA

MARYLAND

Chester County Lancaster County

7.85

8.47

Stream site and nitrate

concentration, in milligrams

per liter as nitrogen

Well and nitrate

concentration, in milligrams

per liter as nitrogen

EXPLANATION

Valley Creek

Knight Run

Muddy Run

Leech Run

7.9

7.11

7.75

3.47

3.97

7.85

9.57

8.57

9.13

6.87

11.7

5.37

3.22

7.37

6.08

11.8

7.63

9.93

7.67

8.47

8.17

11.1

11.1

4.51

5.03 14.2

10.8

5.17

76°10' 76°50' 76° 75°55'

40°

39°55'

39°50'

39°45'

Blackburn

Run

Black Run

0 1 2 4 MILES

0 1 2 4 KILOMETERS
20 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

a compound generally of either sodium chloride or calcium 

chloride. When these salts dissolve, both chloride and sodium 

or calcium are released into the groundwater. The USEPA lists 

a drinking-water advisory for sodium of 20 mg/L for individuals on a restricted sodium diet and a range of 30–60 mg/L 

threshold for adverse taste effects. Sodium concentrations 

ranged from 80 to 160 mg/L in water samples from the two 

wells (CH-2478 and CH-2574) affected by salt storage and 

application of deicing salt on the Turnpike.

On-Site Wastewater Disposal

Various forms of land application of wastewater for 

disposal are common in Chester County and mainly are used 

for disposal of residential wastewater but also for disposal of 

commercial, institutional, or other types of wastewater. Constituents in wastewater that potentially affect groundwater and 

stream base-flow quality include nutrients, salts, selected trace 

elements, anthropogenic organic compounds, and bacteria. In 

many residential settings, individual on-site disposal systems, 

such as septic systems, are standard for each lot. In other 

areas, a large community on-site system may serve multiple 

residences. Large on-site systems may consist of a large septic 

system, sand mounds, or spray irrigation or drip dispersal of 

treated effluent. As of 1998, about 40 percent of the population in the county relied on individual on-lot systems (septic 

systems most common) for wastewater disposal; 46 percent of 

the population is projected to be using on-lot systems in 2020 

(Chester County Water Resources Authority, 2002, p. 74).

Through the Chester County groundwater-quality monitoring program, about 60 groundwater samples were collected 

from 1987 through 2008 to establish a baseline for future comparison, to assess groundwater quality in sewered and unsewered areas, and to investigate the effects of on-site wastewater 

disposal on groundwater quality. In 2005, 2007, and 2008, a 

total of 30 stream base-flow samples also were collected for 

these purposes, because stream base flow integrates groundwater quality from the contributing area. The stream base-flow 

samples also can be used to evaluate the relation between 

groundwater and surface-water quality

Wells sampled to establish baseline water-quality conditions included nine wells sampled in 1988 before the operation 

of individual on-lot systems or large spray-irrigation systems 

commenced and five wells sampled in 1996 near new and proposed community on-lot disposal systems (COLDS), such as 

large sand filter systems (appendix 1). In 2007, two wells and 

seven stream base-flow sites were sampled to establish baseline water quality before spray irrigation of treated wastewater 

in a development in the Beaver Creek Basin. Data obtained 

from resampling these wells could be used to assess the effects 

of the wastewater disposal on groundwater quality. Selected 

other wells (CH-75 and CH-410) that have been resampled 

for a limited number of constituents in areas where spray 

irrigation disposal of wastewater is used showed increases 

in chloride concentrations over time. Chloride concentrations increased from 21 mg/L in 1986 to 33 mg/L in 2000 in 

water samples from well CH-75 and from 26 mg/L in 1986 to 

47 mg/L in 2002 in water samples from well CH-410.

To assess groundwater quality in areas with on-site 

residential wastewater disposal, nine wells on relatively 

small lots (about 1 acre) in residential land use since the 

1970s were sampled in 1995. Analyses were performed for 

major ions, nutrients, selected trace elements, and VOCs. The 

groundwater-quality results, as partially summarized in table 

5, show that concentrations of nitrate, chloride, and boron 

commonly were moderately elevated above estimated natural 

background concentrations of these constituents in groundwater in Chester County. Nitrate concentrations (3.1 to 7.9 mg/L 

as N) were moderately elevated above the natural background 

concentration of about 1 mg/L as N, chloride concentrations (7.3 to 64 mg/L) were near or greater than the natural 

background concentration of 10 mg/L, and boron concentrations (less than 10 to 120 mg/L) were near or greater than 

the natural background concentration of about 10 to 20 μg/L. 

In addition, low concentrations of a few VOCs were measured in samples from six of the nine wells. These man-made 

compounds (VOCs) were likely introduced into groundwater 

through on-site wastewater disposal. The maximum concentrations of detected VOCs were 0.5 μg/L chloroform; 5.32 μg/L 

trichloroethane; 1 μg/L chlorofluorocarbon; 1,1,2-trichloro1,2,2-trifluoroethane (CFC-113); 1.7 μg/L 1,1-dichloroethane; 

1.8 μg/L 1,1-dichloroethene; 0.5 μg/L methyl tert-buytl ether 

(MTBE); and 0.4 μg/L trichloroethylene.

Data collected in 2005 show differences in the quality 

of groundwater and base flow in residential areas with on-site 

wastewater and in residential areas with sewers. In 2005, 

groundwater and stream base-flow samples were collected in 

headwater areas of Broad Run (fig. 4) with various land uses, 

including residential areas with on-site wastewater disposal 

and sewered residential areas (Senior and Cinotto, 2007). 

Concentrations of nitrate and boron generally were higher in 

groundwater and stream base flow in samples from residential areas with on-site wastewater disposal than in samples 

from residential areas that are sewered. These findings are 

consistent with stream base-flow samples collected for other 

studies in Chester County (Senior and others, 1997; Senior 

and Koerkle, 2003) and with other data collected through the 

Chester County groundwater-quality monitoring program.

Selected anthropogenic organic compounds found in 

wastewater, such as pharmaceuticals, detergents, fragrances, 

and solvents, in addition to nutrients and other inorganic 

constituents were analyzed for in groundwater and baseflow samples collected in 2000, 2002, 2005, 2007, and 2008. 

Results for 2000, 2002, and 2005 are described in Senior and 

Cinotto (2007) and indicate that concentrations of nitrate, 

chloride, and boron in groundwater and stream base flow may 

be elevated in areas that receive on-site wastewater disposal 

either by spray irrigation, drip dispersal, or septic systems. 

Anthropogenic organic wastewater compounds were detected 

at low concentrations in groundwater and base-flow samples. 

Results for 2008 samples are briefly described in the following 

paragraphs on groundwater and base-flow quality in the five 
Chester County Groundwater-Quality Monitoring Program 21

areas where land use is predominantly residential and onsite wastewater disposal is prevalent. Anthropogenic organic 

wastewater compounds also were detected in groundwater and 

base-flow samples in an assessment of an area near the dam on 

Beaver Creek in 2007, which is discussed later in this report in 

the section on Other Localized Sources and Targeted Areas.

In 2008, groundwater and base-flow samples were collected in five headwater areas that were predominantly residential with on-site disposal of wastewater to assess the effects 

of wastewater disposal on water quality (fig. 4). One base-flow 

sample was collected in each of the headwater areas. Two 

groundwater samples were collected in each of two headwater 

areas and one groundwater sample was collected in a third. 

Samples were analyzed for major ions, nutrients, selected 

trace elements, and selected organic wastewater compounds. 

Results, except for one groundwater sample collected in 

October 2008, were published online (U.S. Geological Survey, 

2009). Results for selected analyses that are wastewater indicators are listed in table 6.

Nitrate concentrations ranged from 1.86 to 6.57 mg/L as 

N in groundwater samples and from 1.81 to 3.30 mg/L as N 

in stream base-flow samples. These observed nitrate concentrations are elevated above the estimated natural background 

of 1 mg/L, indicating anthropogenic sources of nitrate have 

affected groundwater and base-flow quality. Other constituents 

that indicate possible effects of on-site wastewater disposal 

include concentrations of chloride greater than natural background of 10 mg/L or less and the detection of organic wastewater compounds in groundwater and base-flow samples.

Other Localized Land Uses and Targeted Areas

In addition to the sources listed above, groundwater 

samples were collected near other localized land uses associated with the use of various chemical compounds and constituents and in areas of interest to CCHD and CCWRA where 

groundwater quality was unknown.

Cemeteries

From 1990 through 1997, 10 wells near cemeteries were 

sampled to determine if embalming compounds leached into 

groundwater. Samples were analyzed for formaldehyde and 

selected trace metals, including arsenic and lead. Formaldehyde has been used for embalming since the 19th century. 

Arsenic was used in embalming fluids from the mid 1860s 

to about 1910 when this use of arsenic was banned. Elevated 

concentrations of arsenic, cobalt, copper, iron, lead, and zinc 

in soils were reported in a study of a cemetery in operation 

since the mid 19th century in Ohio and may have been introduced by leaching embalming fluids and breakdown of metal 

components of caskets (Spongberg and Becks, 2000).

The limited data collected as part of the groundwaterquality monitoring program in Chester County show that 

cemeteries may affect groundwater quality nearby with 

contaminants such as formaldehyde present in concentrations 

greater than HA levels. Formaldehyde was detected in 4 of 

the 10 well-water samples collected through the program; 

concentrations ranged from 0.09 to 1.10 mg/L (equivalent of 

90 to 1,100 μg/L) (table 7). The minimum reporting level for 

the formaldehyde analyses ranged from 0.01 to 0.10 mg/L. 

Currently, no drinking-water standard has been established 

for formaldehyde, although the compound is on the draft 

Contaminant Candidate List 3 (CCL3) released by USEPA in 

February 2008 and USEPA has listed a HA level of 1 mg/L for 

formaldehyde in drinking water (table 3).

Elevated concentrations of trace metals were not detected 

in most of the eight samples with metals analyses. These 

results suggest that elevated concentrations of trace metals in 

groundwater in Chester County probably are not associated 

with cemeteries. The highest concentrations of trace metals 

measured were 3 μg/L arsenic, 5 μg/L chromium, 180 μg/L 

Table 5. Concentrations of chloride, boron, nitrate, and orthophosphate detected in samples from nine wells in residential areas with 

on-site wastewater disposal in use since the 1970s, Chester County, Pa.

[mg/L, milligrams per liter; μg/L, micrograms per liter; N, nitrogen; P, phosphorus; <, less than]

U.S. Geological 

Survey local well 

number

Date sampled Chloride

(mg/L)

Boron

(μg/L)

Nitrate

(mg/L as N)

Orthophosphate

(mg/L as P)

CH-4339 9/21/1995 9.6 <10 5.5 0.04

CH-4539 9/21/1995 10.0 10 3.9 .04

CH-5238 9/28/1995 9.5 20 5.6 .03

CH-5259 9/20/1995 64.0 30 6.4 .02

CH-5260 9/26/1995 35.0 120 3.1 .01

CH-5261 9/26/1995 7.3 <10 7.9 < .01

CH-5269 10/11/1995 17.0 40 6.0 .07

CH-5270 10/11/1995 9.6 <10 4.4 .05

CH-5272 10/12/1995 22.0 10 4.3 .05
22 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008 Table 6. Concentrations of nitrate, orthophosphate, chloride, boron, and organic wastewater compounds detected in samples from five wells and five streams in headwater areas that have residential land use with on-site wastewater disposal, Chester County, Pa., 2008. [mg/L as N, milligrams per liter as nitrogen; mg/L as P, milligrams per liter as phosphorus; μg/L, micrograms per liter] Basin U.S. Geological Survey local well number Date Nitrate (mg/L as N) Ortho- phosphate (mg/L as P) Chloride (mg/L) Boron

(μg/L)

Organic wastewater 

compound1

Unnamed tributary to West Branch Brandywine Creek CH-4230 9/18/2008 1.86 0.024 101.0 17.7 isophorone

DEET

Unnamed tributary to West Branch Brandywine Creek CH-4261 9/24/2008 5.10 .012 2.9 9.6 isophoroneBlack Horse Creek CH-5435 9/24/2008 6.57 .021 28.5 25.4 no detectBlack Horse Creek CH-5444 10/02/2008 4.82 .029 15.5 2.1 1,4-dichlorobenzene

DEET

Ridley Creek CH-5445 9/25/2008 4.42 .017 21.9 7.1 isophorone

Stream site 

number

Unnamed tributary to West Branch Brandywine Creek 01480160 9/23/2008 3.08 .012 28.8 20.3 caffeine

benzophenoneDEETp-cresol

Black Horse Creek 014806775 9/30/2008 1.81 .016 27.1 16.9 carbamazepine

DEET

Ridley Creek 01476420 9/24/2008 2.90 .007 34.7 17.8 carbamazepine

p-cresol

Rock Run 01480457 9/23/2008 3.30 .015 23.7 13.5 acetaminophen

caffeinecarbamazepinep-cresol

Unnamed tributary to White Clay Creek 01478147 9/30/2008 2.73 .010 29.3 15.6 metalaxyl

1Uses and occurrences of detected organic wastewater compounds:

acetaminophen (analgesic), caffeine (stimulant), carbamazepine (anticonvulsant), DEET (mosquito repellent), 1,4-dichlorobenzene (moth repellent, fumigant, deodorant) isophorone (solvent for lacquer, plastic, oil, silicon, resin), metalaxyl (herbicide, fungicide), 

p-cresol (wood preservative)
Chester County Groundwater-Quality Monitoring Program 23

copper, 20 μg/L lead, 0.5 μg/L mercury, 13.2 μg/L nickel, 

1 μg/L silver, and 35 μg/L zinc. Beryllium, cadmium, cobalt, 

lithium, and vanadium were not detected, and concentrations 

of most trace metals analyzed were less than the laboratory 

minimum reporting level that ranged from 0.1 μg/L to less 

than 10 μg/L depending on the analysis. Concentrations of 

dissolved iron were higher than the SMCL of 300 μg/L in 

only one sample (5,840 μg/L), and manganese concentrations 

were all less than the SMCL of 50 μg/L. The concentration of 

dissolved lead of 20 μg/L in one well-water sample exceeded 

the action level of 15 μg/L established by USEPA (table 3) for 

lead in drinking water. However, all samples that had detectable concentrations of lead (1 to 20 μg/L) were relatively 

acidic, having pH values of 5.8 or less. These results suggest 

that lead is more soluble in acidic groundwater. The source of 

lead in the groundwater samples is unknown.

County Parks and Other County-Owned Land

Data on groundwater quality in county-owned parks 

and other land were collected through the groundwaterquality monitoring program from 1991 through 1996 to 

identify possible water-quality problems on county-owned 

land and to obtain baseline information for areas that would 

become county-owned land. Wells were sampled in Warwick, 

Hibernia, and Nottingham Parks; in the area to be flooded 

by Hibernia dam; at county-owned desilting basins near the 

Schuylkill River; and on former Church Farm School property 

(fig. 2). The latter included 713 acres that were cooperatively 

purchased in 1994 by West Whiteland Township and Chester 

County to become public open space as Exton Park and in 

part to be used for disposal of wastewater by spray irrigation. 

Samples were analyzed for major ions, nutrients, selected trace 

metals, radon-222, and some anthropogenic organic compounds. Except for the two samples from Nottingham Park, 

analyses also included selected pesticides and VOCs.

Results revealed a few water-quality concerns. Samples 

from two wells at the former Church Farm School property 

sampled in 1991 had elevated nitrate (11 and 13 mg/L as 

N) above the drinking-water MCL of 10 mg/L as N and one 

sample had low concentrations of pesticides (atrazine and 

metolachlor). Other USGS data on groundwater quality at 

Church Farm School are reported by Senior and others (1997). 

Low concentrations of some pesticides (CIAT, simazine) 

and (or) MTBE were measured in samples collected in 1994 

from two wells (CH-5088 and CH-5089) now decommissioned and flooded by Hibernia dam. The sample from one 

well (CH-5226) at Nottingham Park had an elevated pH of 

9.5, which is related to the underlying serpentine rocks. No 

water-quality problems except slightly acidic pH values were 

identified with samples collected from the wells at Warwick or 

Hibernia County Parks (CH-2317 and CH-5087).

Samples were collected in 1993–95 from five wells 

near desilting basins owned by the county along the banks of 

the Schuylkill River that forms the northern border of Chester County. These desilting basins were created in the late 

1940s to hold coal silt and other sediments dredged from the 

Schuylkill River. The dredged materials are known to contain 

trace metals and anthropogenic organic compounds such as 

DDT and PCB (Stamer and others, 1985). Contaminants associated with sediments in the desilting basins potentially could 

leach into nearby groundwater.

Groundwater samples collected from the five wells 

near the desilting basins showed no inorganic water-quality 

problems. Concentrations of trace metals were not elevated in 

the samples, although one sample had 19 μg/L molybdenum, 

which is above the median for Chester County. The molybdenum probably is naturally occurring and related to underlying geology as indicated by data collected in similar Triassic 

rocks (Senior and Sloto, 2006). Molybdenum has no MCL but 

is listed by USEPA as a contaminant of concern on the draft 

CCL3 and has a HA level of 40 μg/L (table 3). Four of the 

Table 7. Concentrations of formaldehyde and lead and pH detected in samples from 10 wells near cemeteries, Chester County, Pa., 

1990 through 1997.

[mg/L, milligrams per liter; μg/L, micrograms per liter; <, less than; --, no data]

U.S. Geological Survey 

local well number Date of sample Formaldehyde(mg/L)

Lead

(μg/L)

Field

pH

CH-4023 9/4/1990 1.10 1 5.7

CH-3561 8/14/1991 < .05 -- 6.6

CH-4125 8/7/1991 < .01 -- 6.3

CH-3184 8/28/1996 .22 <1 7.3

CH-5480 9/11/1996 < .05 <1 6.6

CH-432 9/3/1997 .09 10 5.8

CH-5553 8/12/1997 < .05 <10 6.2

CH-5557 8/25/1997 .10 10 5.0

CH-5558 8/26/1997 < .05 20 4.9

CH-5562 9/8/1997 < .05 <1 6.5
24 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

five samples also were analyzed for VOCs. A low concentration (1.8 μg/L) of PCE was detected in a water sample from a 

well (CH-4502) near the Recticon/Allied Steel Superfund site, 

which is a known source of VOC contamination in groundwater (U.S. Environmental Protection Agency, 2009c). Low concentrations (less than 2 μg/L) of several VOCs (1,1,1-TCA, 

styrene, toluene, TCE) were detected in an industrial well 

(CH-4801) near a desilting basin and probably are related to 

industrial activities in the area.

General Land-Use Assessments

In 1998, to support a study on modeling streamflow and 

water quality in the Christina River Basin, four wells (appendix 1) were sampled to provide data on groundwater quality in 

four different land-use areas. Land uses targeted for sampling 

included row-crop agriculture (well CH-2311), residential 

with on-site wastewater disposal (well CH-5160), sewered 

residential (well CH-4828), and forested (well CH-4817). 

Nitrate concentrations ranged from 0.15 to 11.6 mg/L as N and 

were lowest in the sample from the forested area and highest in the sample from the agricultural area. In addition to a 

nitrate concentration exceeding the MCL of 10 mg/L as N, the 

sample from the well in the agricultural area also contained the 

herbicides cyanazine (0.12 μg/L) and metolachlor (12 μg/L). 

The nitrate concentration was higher in the sample from the 

residential area with on-site wastewater disposal (4.51 mg/L 

as N) than in the sample from the sewered residential area 

(2.79 mg/L as N). The sample from the residential area with 

on-site wastewater disposal had the highest chloride concentration (24.4 mg/L) and the only detection of boron (28 μg/L) 

compared to samples from the three other land-use areas. 

MTBE (a fuel additive) was detected at low levels (0.2 μg/L or 

less) in samples from the agricultural area and the residential 

area with on-site wastewater disposal.

In 2001, 21 wells (appendix 1) were sampled in parts of 

the county where little to no groundwater-quality data were 

available and no localized contaminant sources were known. 

These data were collected to provide a general assessment of 

water quality where unknown and to provide broader spatial 

assessments throughout the county. Water-quality problems 

identified in 2001 included elevated concentrations of nitrate 

above the MCL of 10 mg/L as N in samples from two wells 

(10.6 mg/L as N in well CH-1283 and 13.4 mg/L as N in well 

CH-5998) and detection of low levels of pesticides in water 

from seven wells (CH-1283, CH-1730, CH-5998, CH-6399, 

CH-6400, CH-6402, and CH-6404). More than one pesticide 

was detected in each of these seven wells, but concentrations did not exceed any established MCL. Detected pesticides included alachlor, atrazine, deethyl atrazine, carbofuran, metolachlor, prometon, 2,4-D, and DDE. Metolachlor 

and atrazine were the most commonly detected pesticides, 

found in six and five of the well samples, respectively, at concentrations up to 0.054 μg/L for metolachlor and 0.076 μg/L 

for atrazine. Carbofuran and deethyl atrazine were detected 

in samples from two wells at concentrations up to 0.072 and 

0.266 μg/L, respectively. Alachlor was detected once at a 

concentration of 0.719 μg/L. 2,4-D, DDE, and prometon also 

were detected once at concentrations less than 0.005 μg/L. The 

water-quality problems of elevated nitrate concentrations and 

low pesticide concentrations are most common in agricultural 

areas of the county.

Pre-Development Groundwater and Base-Flow Quality in 

Beaver Creek Basin in 2007

In 2007, groundwater, stream base-flow, and reservoir 

water and sediment samples were collected to establish 

water-quality conditions in an area in the Beaver Creek Basin 

(fig. 4) that was to undergo conversion from agricultural 

(primarily corn and other row crop) to residential and golf 

course land use with planned disposal of treated residential 

wastewater to include spray irrigation onto golf course lands 

near the Beaver Creek sediment pool. Samples were analyzed 

for major ions, nutrients, and selected trace elements and 

organic wastewater compounds. These data can provide a 

baseline for comparison of future sampling results to indicate 

changes in water quality that may occur because of the conversion of land uses. Samples were collected before major land 

disturbance and construction activities had commenced for the 

development project.

The samples collected in 2007 indicated that elevated 

concentrations of nitrate were present in base flow (up to 

21.9 mg/L as N) and groundwater (up to 7.3 mg/L as N) 

(table 8; U.S. Geological Survey, 2008). Some pesticides 

(metolachlor and prometon) were detected in mainstem and 

tributary base flow upstream of and within the sediment pool 

and in Beaver Creek downstream of the dam. Other compounds commonly present in wastewater were detected in the 

sediment pool and its sediments (site 01480744) and in base 

flow (sites 014807447, 01480745, and 01480750) downstream of the dam. More organic wastewater compounds were 

detected in sediment samples than in the water samples and 

concentrations were higher in sediment than stream samples 

(U.S. Geological Survey, 2008).

Base-flow samples from six sites on other streams in 

Chester County (fig. 4) also were analyzed for major ions, 

nutrients, and selected trace elements and organic wastewater compounds to serve as a reference for the Beaver Creek 

watershed samples. Land uses in the drainage areas of these 

six stream sites are primarily agricultural and residential with 

on-site wastewater disposal. Samples collected at the reference sites through time could be used to compare with Beaver 

Creek samples and to help assess non-land-use effects, such 

as atmospheric inputs, on water quality. Nitrate concentrations 

ranged from 2.0 to 4.6 mg/L as N, and several wastewater 

compounds were detected at low concentrations in the baseflow samples (table 8; also see appendix 1, year 2007, for site 

list) (U.S. Geological Survey, 2008), indicating that base-flow 

quality is affected by application of nutrients and wastewater 

to land in the drainage areas.
Chester County Groundwater-Quality Monitoring Program 25

Table 8. Concentrations of nitrate, chloride, boron, and organic wastewater compounds detected in nine base-flow samples and two well-water samples nearBeaver Creek Reservoir and in base-flow samples at five other stream sites collected in 2007 as part of the Chester County groundwater-quality monitoring program,Chester County, Pa.—Continued[mg/L as N, milligrams per liter as nitrogen; mg/L, milligrams per liter; μg/L, micrograms per liter; --, no data; nd, not detected]

U.S. Geological 

Survey station 

number

Name Sample date Nitrate (mg/L as N) Chloride (mg/L) Boron (μg/L)

Organic

wastewater

compounds

detected1

Beaver Creek and tributaries upstream of dam01480739 Beaver Creek above tributary at Reeceville 6/18/2007 10.6 20.8 8.4 metolachlor

p-cresolprometon

01480742 Beaver Creek tributary at Reeceville 6/18/2007 6.2 26.8 10 metolachlor

p-cresol

01480743 Beaver Creek at Reeceville 6/18/2007 9.2 22.6 9.1 metolachlor

p-cresolprometon

014807434 Unnamed tributary to Beaver Creek Reservoir at Reeceville 6/18/2007 21.9 24.2 11 metolachlor014807438 Unnamed Tributary to Beaver Creek Reservoir near Reeceville 6/18/2007 9.8 11.9 18 ndBeaver Creek Reservoir water01480744 Beaver Creek Reservoir near Guthriesville 6/19/2007 -- 22.2 10 3-methyl-1H-indole

isophoronemetolachlorprometon

Beaver Creek downstream of dam014807447 Beaver Creek Reservoir outfall at Reeceville 6/18/2007 6.9 21.6 11 3-methyl-1H-indole

isophoronemetolachlorprometon

01480745 Beaver Creek at Guthriesville 6/18/2007 7.1 21.3 10 3-methyl-1H-indole

isophoronemetolachlorprometon

01480750 Beaver Creek at Bondsville 8/27/2007 5.2 17.4 12 methyl salicylate

metolachlor

Well-water samples near Beaver Creek ReservoirCH-7220 9/6/2007 7.3 4.2 14 ndCH-7236 9/6/2007 6.6 102 69 tetrachloroethylene

tris(dichloroisopropyl) phosphate
26 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008 Table 8. Concentrations of nitrate, chloride, boron, and organic wastewater compounds detected in nine base-flow samples and two well-water samples near Beaver Creek Reservoir and in base-flow samples at five other stream sites collected in 2007 as part of the Chester County groundwater-quality monitoring program, Chester County, Pa.—Continued [mg/L as N, milligrams per liter as nitrogen; mg/L, milligrams per liter; μg/L, micrograms per liter; --, no data; nd, not detected] U.S. Geological Survey station number Name Sample date Nitrate (mg/L as N) Chloride (mg/L) Boron

(μg/L)

Organic

wastewater

compounds

detected1

Selected headwater streams in Chester County01472080 Pigeon Creek near Slonaker 11/8/2007 2 13.5 10 camphor

methyl salicylatep-cresol

01472110 Stony Run at Spring City 11/7/2007 3.7 21.5 18 camphor

DEETHHCBmethyl salicylate

014806215 Buck Run at Sadsburyville 11/14/2007 4.6 34.1 9.9 caffeine

camphormethyl salicylatemetolachlor

0148063528 Broad Run above Unnamed Tributary at Romansville 8/27/2007 3.4 24.7 7.9 methyl salicylate01480656 Indian Run near Springton 8/28/2007 3 17.9 12

p-cresoltris(2-chloroethylphosphate)

01480662 Culbertson Run at Lyndell 8/28/2007 3.6 28.2 24 caffeine

methyl salicylatemetolachlorp-cresol

1Uses and occurrences of detected organic wastewater compounds:

caffeine (stimulant), camphor (flavorant), DEET (mosquito repellent), HHCB (musk fragrance), isophorone (solvent for lacquer, plastic, oil, silicon, resin), 3-methyl-1H-indole (fragrance, stench in feces and coal tar), methyl salicylate (liniment, food, beverage, UV-absorbing lotion), metolachlor (herbicide), 

p-cresol (wood preservative), tetrachloroethylene (solvent), tris(2-chloroethylphosphate) (plasticizer), tris(dichloroisopropyl) phosphate (flame retardant)
Chester County Groundwater-Quality Monitoring Program 27

Chloride as Indicator of Land-Use Change

Widespread introduction of chloride from human activities to land surface or near surface includes use of deicing salts 

on roads and on-site wastewater disposal in Chester County. 

Increases in chloride application may be anticipated in areas of 

the county that undergo residential development and urbanization because of increases in road density and the number 

of on-site wastewater disposal systems. Chloride also may 

be applied to the land surface to a lesser extent in other land 

uses, such as agriculture (Mullaney and others, 2009). Chloride applied at or near the land surface readily dissolves and 

infiltrates through soils to the groundwater system. Once dissolved, chloride is a relatively conservative solute and is not 

degraded, adsorbed, or precipitated out of solution. Chloride 

as a tracer travels with groundwater flow.

As noted earlier, groundwater quality can change through 

time because of changes in land use and associated constituent 

sources at the land surface as well as other factors. Information about the extent of changes in chloride concentrations in 

groundwater is available for some wells in Chester County 

that have been sampled more than once. In addition, data on 

long-term changes in chloride concentrations in base flow 

in Chester County are available from a separate monitoring 

program (Reif, 2002a).

Well-Water Samples

Chloride concentration data are available for 65 wells that 

have been sampled more than once in the county through the 

monitoring program. Forty-eight of the 65 wells were sampled 

at least 5 years apart. Comparison of the earliest and latest 

samples from the 48 wells indicates that chloride concentrations increased through time in about 80 percent of the wells 

sampled. Generally, the range and median increases in chloride concentrations are greatest for samples collected more 

than 20 years apart and least for samples collected less than 

10 years apart. The median increase in relative (and actual) 

chloride concentration was 238 percent (31 mg/L) for 17 wells 

sampled 20–40 years apart, 55 percent (12 mg/L) for 23 wells 

sampled 10–19 years apart, and 20 percent (4.5 mg/L) for 14 

wells sampled 5–9 years apart. For the 17 wells sampled less 

than 5 years apart, the median change in relative (and actual) 

chloride concentration is about 6 percent (1 mg/L), indicating 

little change over that period. These reported differences in 

chloride concentrations are for samples typically collected in 

late summer or early fall and are not expected to be affected to 

a major extent by seasonal changes in recharge and chloride 

loading rates.

 To determine long-term trends, however, determination of seasonal fluctuations would be important as would 

more frequent sampling of a set of wells over an extended 

period (years). In a separate study, Sloto (1994) sampled six 

wells monthly for about a year to measure seasonal changes 

in concentrations of major ions and reported that the fluctuations in chloride concentrations over the year ranged from 

19 to 180 percent, with a median of 25 percent. The range of 

monthly or seasonal fluctuations over a year is needed to allow 

comparison of short-term (month) to long-term (multipleyear) changes and to determine long-term trends. Sloto (1994) 

also reported for comparison of 1946–76 to 1982–83 data 

that median long-term increases in chloride concentrations in 

groundwater were greater in sewered areas than in non-sewered areas, which may be related to the greater use of road salt 

in the usually more densely populated sewered areas.

Thus, increases in chloride concentration in groundwater 

probably reflect urbanizing trends in the county. Increases in 

chloride are likely to be accompanied by increases in other 

ions from salt sources, such as sodium and calcium, and perhaps by other constituents associated with urbanization.

Stream Base-Flow Samples

Although the Chester County groundwater-quality monitoring program currently has no formal temporal component, 

some understanding of selected long-term trends in groundwater quality may be gained from evaluation of relatively conservative constituents, such as chloride, and to a lesser extent, 

nitrate in base-flow samples collected annually in the autumn 

through the Chester County biological and chemical network 

(Reif, 2002a). These base-flow samples, which are analyzed 

for major ions and nutrients, integrate the quality of groundwater that discharges to the stream above the sampling site. 

The base-flow data generally reflect the multiple land uses and 

geology in the drainage area and cannot be used to determine 

local changes in groundwater quality that might be associated 

with local land-use change.

Trends have been observed in base-flow inorganic quality and inferred groundwater quality for streams that have no 

point discharges. Statistical analysis indicates that chloride 

concentrations in base flow increased from 1971 to 1993 in 

the urbanizing West Valley Creek Basin (Senior and others, 

1997) and from 1970 to 1996 in the East and West Branches of 

Red Clay Creek (Senior, 1996) (fig. 4). The data from 1996 to 

2007 show that the increases in chloride concentrations in base 

flow at East Branch Red Clay Creek appear to have continued 

(fig. 6A). Similar trends of increasing chloride concentrations 

in base flow from 1969 to 2007 are indicated by annual data 

collected in some other streams without point discharges in 

Chester County (fig. 6B-E). Reif (2002a) noted increases in 

base-flow specific conductance, a measurement that indicates 

the amount of dissolved constituents including chloride, from 

1981 to 1997 at 36 of 43 stream sites. Nitrate concentrations 

in base flow increased at several sites without point discharges 

during that time period and in the Valley Creek tributary to 

the Octoraro Creek increased from less than 4 mg/L as N in 

1981 to more than 9 mg/L as N in 1997 (Reif, 2002b). The 

increasing trends of chloride and nitrate in streams without 

point discharges reflect increasing loads of these constituents 

from land uses. As land becomes more intensively developed 

(including urban and agricultural uses), the effects of associated constituents are likely to result in changes to groundwater 

and base-flow quality.
28 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Figure 6. Chloride concentrations in base flow sampled annually in autumn at USGS 

streamgages: (A) 01479800 East Branch Red Clay Creek near Five Points, Pa., 1970–2007; 

(B) 01480653 East Branch Brandywine Creek near Glenmoore, Pa., 1969–2007; (C) 01472157 

French Creek near Phoenixville, Pa., 1969–2007; (D) 01472080 Pigeon Creek near Slonaker, 

Pa., 1969–2007; and (E) 01472190 Pickering Creek near Phoenixville, Pa., 1967–2007. 

Locations of streamgage sites are shown on figure 4.

0

10

20

30

40

50

60

70

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

BASE-FLOW CHLORIDE CONCENTRATIONS, 

IN MILLIGRAMS PER LITER

A 01479800 Red Clay Creek near Five Points, Pa.

0

2

4

6

8

10

12

14

16

18

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

B 01480653 East Branch Brandywine Creek at Glenmoore, Pa.

0

2

4

6

8

10

12

14

16

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

C 01472157 French Creek near Phoenixville, Pa.

BASE-FLOW CHLORIDE CONCENTRATIONS, 

IN MILLIGRAMS PER LITER

BASE-FLOW CHLORIDE CONCENTRATIONS, 

IN MILLIGRAMS PER LITER
Chester County Groundwater-Quality Monitoring Program 29

Figure 6. Chloride concentrations in base flow sampled annually in autumn at USGS 

streamgages: (A) 01479800 East Branch Red Clay Creek near Five Points, Pa., 1970–2007; 

(B) 01480653 East Branch Brandywine Creek near Glenmoore, Pa., 1969–2007; (C) 01472157 

French Creek near Phoenixville, Pa., 1969–2007; (D) 01472080 Pigeon Creek near Slonaker, 

Pa., 1969–2007; and (E) 01472190 Pickering Creek near Phoenixville, Pa., 1967–2007.—

Continued. Locations of streamgage sites are shown on figure 4.

0

2

4

6

8

10

12

14

16

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

D 01472080 Pigeon Creek near Slonaker, Pa.

0

5

10

15

20

25

30

35

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

E 01472190 Pickering Creek near Phoenixville, Pa. 

BASE-FLOW CHLORIDE CONCENTRATIONS, 

IN MILLIGRAMS PER LITER

BASE-FLOW CHLORIDE CONCENTRATIONS, 

IN MILLIGRAMS PER LITER
30 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Results of Sampling for Naturally Occurring 

Constituents

Data on general water chemistry and naturally occurring 

constituents in groundwater that may pose a risk to human 

health were collected through the groundwater-quality monitoring program. Groundwater quality is partly controlled by 

chemical reactions in the soil, saprolite (weathered rock), and 

underlying bedrock. Reactions include mineral dissolution, 

ion exchange, and adsorption. These natural controls differ by 

rock type.

General Water Chemistry—pH, Alkalinity, Major 

Ions, Iron, and Manganese

Field data on pH, alkalinity, dissolved oxygen concentration, and specific conductance were collected on a routine basis for the groundwater-quality monitoring program. 

Concentrations of major ions, iron, and manganese also were 

commonly determined during sample analysis. These data 

can be used to understand and characterize the general water 

chemistry associated with each well sample and associated 

aquifer, including potential water-quality problems that exceed 

the SMCLs. For example, pH data can be used to evaluate the 

acidity of the groundwater, which affects corrosion of plumbing and mobilization of trace elements in the aquifer. Some 

trace elements, including lead and radium that pose risks to 

human health, are more soluble at low pH than at intermediate 

or high pH.

In Chester County, SMCLs for pH (6.5–8.5), iron 

(300 μg/L), and manganese (50 μg/L) are the most frequently 

exceeded secondary standards. Iron concentrations are 

greater than the SMCL of 300 μg/L in more than 10 percent 

of well-water samples countywide, and manganese concentrations are greater than the SMCL of 50 μg/L in more than 

20 percent (Sloto, 1994; Ludlow and Loper, 2004). The data 

on general water chemistry are summarized for major aquifer type in Chester County by Sloto (1994) and Ludlow and 

Loper (2004).

Radionuclides

Naturally occurring radionuclides (radioactive elements derived from the radioactive decay of uranium-238, 

thorium-238, and uranium-235), such as radium and radon, 

are present in some rocks, soils, and groundwater in Chester 

County. Radionuclides are unstable elements, with half-lives 

of varying lengths (from seconds to millions of years), and are 

part of radioactive decay series defined by the primary parent, 

such as uranium-238. Radionuclides with longer half lives 

typically are present in greater mass quantities than radionuclides with shorter half lives. Radionuclides may include 

radioactive isotopes of the same elements, such as radium-226 

and radium-228, that are produced by the radioactive decay of 

different parent radionuclides. Radon-222, a gas, is produced 

from the decay of radium-226, itself a daughter product in the 

uranium-238 decay chain. Radioactive decay releases alpha 

or beta particles, the amount of which commonly is measured 

and reported as gross alpha-particle or gross beta-particle 

activity. Radionuclides and associated radioactivity may pose 

a risk to human health in drinking water. The USEPA has 

established MCLs for radium-226, radium-228, uranium, gross 

alpha particles, and gross beta particles and has proposed 

MCLs for radon-222 (table 3). The amount of radionuclides 

present in a sample commonly is reported in units of picocuries per liter, which is a measure of the rate of decay and is 

called an activity rather than a concentration.

Samples for analysis of naturally occurring radionuclides 

in Chester County were collected through the groundwaterquality monitoring program on an intermittent basis from 1984 

through 2003. The results revealed that radionuclides are present in groundwater at levels that may pose health risks in some 

areas of the county. Radiochemical data collected through 

2000 in southeastern Pennsylvania, including Chester County, 

are summarized by Sloto (2000) and through 2001 in Chester 

County by Ludlow and Loper (2004).

The CCHD has considered a recommendation that water 

samples from new wells drilled in the Chickies Quartzite and 

other quartzite units in the county (Setters Quartzite, Peters 

Creek Schist, Antietam and Harpers Formation, undivided) 

be screened for gross alpha-particle and (or) radium activities depending on the pH of the groundwater (Ralph DeFazio, 

Chester County Department of Health, oral commun., 2009). 

This recommendation to protect human health is based on 

results of the groundwater-quality monitoring program in 

Chester County and other studies of radionuclides in southeastern Pennsylvania (Senior and Vogel, 1995; Sloto, 2000).

Radium and Radon

In 1984, a sample from one well (CH-2429) in the 

Chickies Quartzite near a suspected dump was analyzed for 

selected radionuclides in addition to VOCs. Elevated activities of radium-226 and gross alpha particles were measured 

above the USEPA MCLs of 5 and 15 pCi/L, respectively, for 

those constituents. In 1985, samples from five of six wells in 

the Chickies Quartzite were analyzed for radionuclides and 

found to have elevated radium-226, radium-228, and gross 

alpha-particle activities above USEPA MCLs (table 3), with 

up to 11 pCi/L for radium-226, 51 pCi/L for radium 228, and 

160 pCi/L for gross alpha. The Chickies Quartzite occurs in a 

band across central Chester County and in several other areas 

in northern Chester County (fig. 1).

In 1986, sampling was expanded to include 30 wells—8 

in the Chickies Quartzite and 1 to 2 in each of 21 major 

geologic units in Chester County—to assess the potential 

for naturally occurring radionuclides countywide. In 1987, 

the countywide radionuclide reconnaissance was expanded 

and sampling included 18 wells in the Triassic rocks (shales 

and sandstones) of northern Chester County and 16 wells in 

quartzite and carbonate rocks. Water from 8 of the 64 wells 
Chester County Groundwater-Quality Monitoring Program 31

sampled in 1986 and 1987 had radium-226, radium-228, or 

gross alpha-particle activities that exceeded USEPA MCLs. Of 

the eight wells, seven were completed in quartzite or quartzite 

schist (five in Chickies Quartzite, one in Peters Creek Schist, 

one in Antietam and Harpers Formation, undivided) and one 

in carbonate rock (Ledger Dolomite) that also had an elevated 

uranium concentration. On the basis of these reconnaissance 

data, the geologic units most likely to have elevated radium 

and gross alpha-particle activities in groundwater in Chester County are the Chickies Quartzite and other quartzites, 

although other geologic rock units in the county also have 

potential for elevated radioactivity in groundwater.

Subsequently, a study of radium and radon in groundwater in the Chickies Quartzite in southeastern Pennsylvania, done by USGS in cooperation with three Pennsylvania 

state agencies (Senior and Vogel, 1995), indicated combined 

radium-226 plus radium-228 activities exceeded the MCL of 

5 pCi/L in more than 40 percent of 160 well-water samples 

collected in Chester County and 5 other nearby counties in 

southeastern Pennsylvania. Of the 45 well samples collected 

in Chester County for the study, 62 percent exceeded the MCL 

for combined radium. Elevated radium activities correlated 

with acidic groundwater, and all samples with pH of 4.7 or 

lower had elevated combined radium activities.

Starting in 1986, groundwater samples collected for the 

Chester County groundwater-quality monitoring program 

were analyzed for radon-222, a radioactive gas that is the 

daughter product of radium-226 radioactive decay. From 

1987 through 2000, all samples collected through the Chester County groundwater-quality monitoring program were 

analyzed for radon-222. These data and data collected through 

other projects from 1986 through 1997 were summarized and 

discussed by Senior (1998) and data collected from 1986 to 

2001 was summarized by Ludlow and Loper (2004). Results 

indicate that radon-222 activities exceeded the proposed MCL 

of 300 pCi/L for 89 percent of the wells and exceeded the 

alternative proposed MCL of 4,000 pCi/L for 18 percent of the 

wells sampled in Chester County (Ludlow and Loper, 2004). 

The highest measured radon-222 activity in groundwater in 

the county was 53,000 pCi/L. Radon-222 activities in groundwater differ by geologic unit. The Peters Creek Schist has the 

highest median radon-222 activities in groundwater in the 

county (Senior, 1998).

In addition to spatial data collected on radon-222 and 

other radionuclides throughout Chester County, some wells 

were sampled on fixed time intervals as part of the groundwater-quality monitoring program to investigate the range of and 

possible seasonal fluctuations in radon activities in groundwater. Results, discussed by Senior (1998), showed that five 

wells sampled bimonthly in 1996–97 had no clear seasonal 

pattern in radon-222 activities in groundwater, although 1996 

was an unusually wet year and may not be representative of 

typical seasonal cycles. Sampling of another well (CH-3335) 

on a monthly interval for about 3 years starting in 1989, 

however, showed strong seasonal fluctuations in radon and 

radium activities; radium activities were highest in the fall and 

lowest in the spring. The implications of seasonal fluctuations 

in groundwater quality may be that drinking-water standards 

could be exceeded seasonally but might not be detected if the 

well were not sampled during the time of year when maximum 

concentrations occur.

In 1999, 14 wells previously sampled in 8 different 

geologic units for analyses of radium-226 and radium-228 

were resampled through the monitoring program for analyses of radium-226, radium-228, and radium-224 (a shortlived radionuclide derived from the decay of radium-228). 

The geologic units included quartzites (two wells in Setters 

Quartzite and four wells in Chickies Quartzite), quartzschist 

(two wells in Antietam and Harpers Formation, undivided and 

one well in Peters Creek Schist), gneiss (one well in felsic 

gneiss), carbonates (one well each in Conestoga Limestone 

and Ledger Dolomite), and shale (two wells in Brunswick 

Group). Radium-224 has a half-life of 3.6 days and decays by 

emitting alpha particles. Its presence may be associated with 

elevated gross alpha-particle activity especially in the first 

few days after sample collection. The short-lived nature of the 

alpha-emitting radium-224 contributes to gross alpha-particle 

activity and has implications regarding the MCL for gross 

alpha-particle activity and the amount of holding time before 

sample analysis (Focazio and others, 2001). Radium-224 

activities up to 265 pCi/L and gross alpha-particle activities 

up to 1,290 pCi/L were measured in a sample from one well 

(CH-3331) completed in the Chickies Quartzite. Samples 

from 7 of the 14 wells had gross alpha-particle activities 

greater than the USEPA MCL of 15 pCi/L (fig. 7). Although 

the USEPA has not established a MCL for radium-224, 

standards have been established in other countries to protect 

human health, such as the Canadian drinking-water guideline 

of 54 pCi/L (2 bequerel) for radium-224 (Health Canada, 

2008). In addition to the sample from well CH-3331, a sample 

from a second well in the Chickies Quartzite (CH-1616) 

had radium-224 activity (61 pCi/L) exceeding the Canadian 

standard. Radium-224 activities in the water samples from 

14 wells correlated with gross alpha-particle and radium-228 

activities (fig. 7).

Radium-224 is likely to occur where radium-228 is present in groundwater, which in Chester County includes quartzite and quartzite schists (Senior and Sloto, 2000) (fig. 1). The 

radium-224 activity of 265 pCi/L measured in the well-water 

sample collected in 1999 in Chester County is one of the 

highest reported in the United States, exceeding the maximum 

activity of 73.6 pCi/L radium-224 reported in a nationwide 

targeted survey of radionuclides in public drinking-water 

supplies in areas with known or suspected elevated radium in 

groundwater (Focazio and others, 2001).

Gross Alpha-Particle and Beta-Particle Activity and Other 

Radionuclides

In 2003, samples from 18 wells collected to investigate 

lead concentrations in the Chickies Quartzite (discussed in 

a later section) were also analyzed for gross alpha-particle 
32 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Figure 7. Radium-224 activities in relation to (A) gross alpha-particle activities and (B) radium-228 activities in 

samples from 14 wells in 9 different geologic units, Chester County, Pa., 1999.

0.10

1

10

100

1,000

1 100 10,000

A

MCL of 15 pCi/L

EXPLANATION

0.1

1

10

100

1,000

0.10 1 10 100 1,000

B

MCL of 5 pCi/L

APPROXIMATE DETECTION LEVEL

GROSS ALPHA-PARTICLE ACTIVITY, IN PICOCURIES PER LITER

RADIUM-228 ACTIVITY, IN PICOCURIES PER LITER

RADIUM-224 ACTIVITY, IN PICOCURIES PER LITER RADIUM-224 ACTIVITY, IN PICOCURIES PER LITER

Brunswick Group

Ledger Dolomite

Conestoga Limestone

Peters Creek Schist

Setters Quartzite

Chickies Quartzite

Harper-Antietam Formation

Felsic gneiss
Chester County Groundwater-Quality Monitoring Program 33

activities measured at two different times after sample collection (72 hours and 30 days) and the radioactive isotope 

lead-210 (also discussed later in the section on lead). Gross 

alpha-particle activities at 30 days exceeded the USEPA 

MCL of 15 pCi/L in 8 of the 18 well-water samples collected 

in 2003; elevated activities ranged from 15.9 to 75.7 pCi/L. 

Gross alpha-particle activities measured at 72 hours generally 

were greater than activities at 30 days (fig. 8), indicating the 

presence of short-lived alpha-particle-emitting radionuclides 

such as radium-222. In one sample, gross alpha-particle activities measured at 72 hours were above the MCL of 15 pCi/L, 

but the 30-day gross alpha-particle activity was less than 

15 pCi/L. The difference between the gross alpha-particle 

activity at 72 hours and 30 days measured in these samples 

ranged up to a factor of 7 and showed that short-lived radionuclides are present in groundwater. Therefore, the use of gross 

alpha-particle activity measurements at 30 days may be insufficient to monitor potential exceedances of MCLs in some 

settings, as has been noted by Focazio and others (2001) for 

areas in New Jersey with radium-224 in groundwater. Gross 

alpha-particle activities appeared inversely related to pH, with 

higher gross alpha-particle activities associated with lower 

(acidic) pH values. All five samples with pH below 5.0 had 

gross alpha-particle activities above the MCL (fig. 9). Elevated 

gross alpha-particle activities in groundwater probably are 

related to the presence of radium-226, radium-224, and other 

radionuclides that decay by alpha-particle emission.

In 2006, samples from 10 wells analyzed for dissolved 

and total lead were also analyzed for gross alpha-particle and 

beta-particle activities measured at 72 hours and at 30 days. 

The wells were completed in different geologic units, including sandstone, carbonate, gneiss, schist, and quartzite rocks. 

Gross alpha-particle and beta-particle activities were substantially greater (by more than 9 pCi/L) at 72 hours compared to 

activities at 30 days in samples from only two wells (CH-3334 

and CH-3365), and both those wells were completed in the 

Chickies Quartzite. Gross alpha-particle activities at 72 hours 

were slightly higher (3.3 pCi/L or 47 percent) than at 30 days 

in a sample from a well in Setters Quartzite (CH-2766). 

The decline in measured activities from 72 hours to 30 days 

indicates the presence of short-lived radionuclides such as 

radium-224 and its progeny that have been shown to occur in 

groundwater in the Chickies Quartzite through samples collected in 1999 as part of the monitoring program.

Arsenic

Arsenic is a naturally occurring element that may be 

present in groundwater in concentrations that pose a risk to 

human health. The USEPA lowered the MCL for arsenic in 

drinking water from 50 to 10 μg/L in 2006 and lists a HA level 

of 2 μg/L (U.S. Environmental Protection Agency, 2009a). 

Through the groundwater-quality monitoring program, data 

on arsenic concentrations in Chester County were collected 

periodically by sampling near possible sources, including those that are associated with human activities such as 

0.1

1

10

100

1,000

0 .1 1 10 100 1,000

30-DAY GROSS ALPHA-PARTICLE ACTIVITY,

IN PICOCURIES PER LITER

72-HOUR GROSS ALPHA-PARTICLE ACTIVITY,

IN PICOCURIES PER LITER

MCL of 15 pCi/L

MCL of 15 pCi/L

Figure 8. Relation between 72-hour gross alpha-particle 

activities and 30-day gross alpha-particle activities in 

groundwater samples from 18 wells in the Chickies Quartzite or 

Antietam and Harpers Formation, undivided, Chester County, Pa., 

2003.

0

10

20

30

40

50

60

70

80

90

3 4 5 6 7

pH

MCL of 15 pCi/L

30-DAY GROSS ALPHA-PARTICLE ACTIVITY, 

IN PICOCURIES PER LITER

pH = 5 

Figure 9. Relation between 30-day gross alpha-particle 

activities and pH in groundwater samples from 18 wells 

in the Chickies Quartzite or Antietam and Harpers 

Formation, undivided, Chester County, Pa., 2003.
34 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

orchards (where arsenic may have been used as a pesticide) 

and cemeteries (arsenic used in embalming agents) and those 

that are naturally occurring such as near mineralized areas. 

Arsenic concentrations in groundwater greater than the MCL 

of 10 μg/L were rare, occurring in only 2 or less than 1 percent 

of about 450 samples from 372 wells. Arsenic concentrations 

greater than the HA level of 2 μg/L were more common and 

were measured in about 13 percent of the samples.

 On the basis of data collected through the groundwaterquality monitoring program and elsewhere in southeastern 

Pennsylvania (Senior and Sloto, 2006), groundwater in the 

Triassic rocks in northern Chester County (fig. 1) is the most 

likely geologic setting in the county to have elevated arsenic concentrations from natural sources. Concentrations of 

arsenic greater than or equal to the HA level of 2 μg/L were 

present in about 40 percent of samples from 41 wells in the 

Triassic geologic units and in only about 7 percent or less of 

water samples from wells in other geologic units in Chester 

County. About 20 percent of samples from the 41 wells in 

the Triassic rocks in northern Chester County had 5 μg/L or 

more of dissolved arsenic, although concentrations exceeded 

the MCL of 10 μg/L in only one sample (from well CH-5556) 

that had 69 μg/L. Less than 2 percent of samples from wells 

in other geologic units had arsenic concentrations greater than 

5 μg/L, and in these samples, the highest concentration was 

10 μg/L. Evaluation of available arsenic data in groundwater 

in Triassic rocks in Chester County and three nearby counties 

in southeastern Pennsylvania indicated that about 10 percent of well-water samples have arsenic concentrations that 

exceed the MCL of 10 μg/L (Senior and Sloto, 2006). Arsenic 

in groundwater in the Triassic rocks in Chester County and 

nearby counties likely is naturally occurring. Studies of similar 

rocks in New Jersey (Serfes, 2006; Serfes and Spayd, 2006) 

showed that arsenic in groundwater was derived from natural 

aquifer materials.

Lead

Data on concentrations of dissolved lead in groundwater 

were collected through the monitoring program at various 

times. Results, as reported by Sloto (1994) for 1980–89 and 

by Ludlow and Loper (2004) for 1990–2001, suggest that 

fewer than 5 percent of 514 well-water samples contained 

dissolved lead in concentrations above the USEPA action level 

of 15 μg/L for drinking water. Lead is a naturally occurring 

element but also is present in some plumbing. Lead may be 

mobilized from natural sources (minerals) or other sources 

under some geochemical conditions (such as low pH or acidic 

water). Reported occurrences of elevated lead in groundwater 

from some wells in the Chickies Quartzite prompted additional 

study. Lead in groundwater was the focus of the groundwaterquality monitoring program in 2003, 2004, and 2006.

In 2003, 18 wells were sampled for concentrations of 

dissolved and total lead in areas underlain by the Chickies 

Quartzite and (or) the Antietam and Harpers Formations, 

undivided, near the Blosenki Superfund site and elsewhere in 

Chester County as a follow-up to USEPA and county findings of elevated lead concentrations in water. In addition 

to lead, samples were analyzed for major ions, nutrients, 

selected trace elements (arsenic, boron, iron, and manganese), 

the isotope lead-210, radon-222, and gross alpha-particle 

activity. Gross alpha-particle activities were analyzed in 

part to verify earlier findings in groundwater in the Chickies 

Quartzite. Lead-210 was analyzed to determine if radioactive 

decay might be a source of lead in groundwater. Lead-210 

is a product of the radioactive decay of radon-222, which 

itself is a decay product of radium-226. Elevated activities of 

radium-226, radium-228, and radon-222 in addition to gross 

alpha particle, have been documented in groundwater in the 

Chickies Quartzite through the monitoring program and other 

studies (Senior and Vogel, 1995).

Results of the 2003 sampling showed that water from 

only 1 (5.5 percent) of the 18 wells sampled had concentrations of dissolved and (or) total lead greater than the USEPA 

action level of 15 μg/L. The highest concentration was 

19.9 μg/L of total lead. Concentrations of dissolved lead 

ranged from 0.2 to 8.8 μg/L, and concentrations of total 

lead ranged from 0.3 to 19.9 μg/L. Most (16 of 18 or about 

90 percent) of the concentrations of total lead were less than 

5 μg/L. The difference between concentrations of dissolved 

and total lead was less than 1 μg/L in 14 of the 18 well-water 

samples, and in the other 4 well-water samples, the concentrations of total lead were greater than concentrations of dissolved lead by 1.3 to 18.6 μg/L. Concentrations of dissolved 

and total lead appear inversely related to pH, such that the 

lower the pH, generally the higher the concentrations of lead 

(fig. 10). The field pH for the 17 samples ranged from 4.2 to 

6.1, and lead concentrations were above 1 μg/L in all samples 

with pH below 5.2. Gross alpha-particle activities in these 

samples (discussed earlier) generally also were inversely 

related to pH, such that both higher gross alpha-particle activities and dissolved lead concentrations were associated with 

lower pH values.

Activities of the isotope lead-210 did not appear to correlate with concentrations of dissolved or total lead but did 

appear to correlate with activities of radon-222 (fig. 11), a parent in the radioactive decay chain. These results suggest that 

the radioactive decay of radon-222 is a primary source of lead210 in the samples although there also may be other sources. 

Lead-210 activities ranged from 0.1 to 3 pCi/L, and associated 

radon-222 activities ranged from 200 to 15,600 pCi/L (fig. 11). 

Although the USEPA has not established a MCL for lead-210, 

the agency included lead-210 on a list for unregulated contaminant monitoring in 1999 (U.S. Environmental Protection 

Agency, 1999) and other countries have established standards, 

such as the Canadian guideline of 2.7 pCi/L (0.1 bequerel per 

liter) lead-210 in drinking water (Health Canada, 2008). The 

highest measured lead-210 activity of 3 pCi/L in the 2003 

well-water samples was above the Canadian guideline of 

2.7 pCi/L for lead-210 in drinking water. Decay of lead-210 

produces polonium-210, a potentially hazardous radionuclide 

that was not analyzed in these samples.
Chester County Groundwater-Quality Monitoring Program 35

Figure 10. Relation between concentrations of dissolved and total lead and pH in groundwater 

samples from 17 wells in the Chickies Quartzite or Antietam and Harpers Formation, undivided, 

Chester County, Pa., 2003.

0.1

1

10

100

3 4 5 6 7 8

DISSOLVED OR TOTAL LEAD, IN MICROGRAMS PER LITER

pH

Dissolved lead

Total lead

Action level of 15 micrograms per liter

0

0.5

1

1.5

2

2.5

3

3.5

0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000 18,000

LEAD-210 ACTIVITY, IN PICOCURIES PER LITER

RADON-222 ACTIVITY, IN PICOCURIES PER LITER

Figure 11. Relation between lead-210 activities and radon-222 activities in groundwater samples 

from 17 wells in the Chickies Quartzite or Antietam and Harpers Formation, undivided, Chester 

County, Pa., 2003.
36 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

In 2004, USGS data on lead in groundwater in the county 

were reviewed to determine the extent of possible lead concentrations higher than the USEPA action level of 15 μg/L. 

Data were compiled and relations between dissolved lead and 

selected chemical properties and constituents and geology 

were cursorily evaluated. The data on lead concentrations in 

well-water samples were collected over a period of more than 

30 years, during which time changes in laboratory and sampling methodology occurred, in addition to possible changes in 

well-owners’ plumbing and natural conditions. The 2004 data 

evaluation did not include screening of the data for different 

laboratory detection levels or other methodologies, which 

may affect some of the preliminary findings. The unpublished, 

internal 2004 review of data on lead in groundwater resulted 

in the following observations.

Data on concentrations of dissolved lead were available 

for 545 wells (690 samples), and concentrations were detected 

above the reporting level for 290 wells (331 samples collected 

between 1972–2003); 35 samples from 31 wells were reported 

to have a concentration equal to 0. Data on concentrations of 

dissolved and total lead were available for 20 wells—3 wells 

in 2001 in the French Creek mine area and 17 wells in 2003 in 

the quartzites.

To evaluate the possible role of water quality on solubility of lead from either man-made sources, such as plumbing, 

or natural deposits, relations between lead and other metals 

possibly associated with plumbing (such as copper and zinc) 

and between lead and geochemical factors such as pH (acidity) were determined for the complete data set that included 

groundwater samples from numerous different geologic units. 

Most groundwater samples collected for the groundwatermonitoring program were from domestic wells through existing plumbing, a possible source of metals such as copper and 

lead. To minimize contamination from plumbing, groundwater 

samples were collected after pumping the well (for variable 

amounts of time that typically ranged from 0.5 to 1.5 hours) 

to purge water that had been in contact with plumbing. For 

the 290 well-water samples with concentrations of dissolved 

lead above the reporting level, dissolved lead did not appear to 

correlate with the dissolved metals copper, iron, manganese, or 

zinc, suggesting that sources other than metal plumbing may 

contribute lead or that plumbing composition varies too widely 

to correlate with lead. Dissolved lead did not appear to correlate with pH when data for all geologic units were combined, 

suggesting that pH is not the sole factor controlling solubility 

of lead. Of the metals copper, lead, and zinc, only copper concentrations appeared to correlate with pH, with dissolved copper concentrations increasing as pH decreases. These results 

suggest that copper may be more easily dissolved than the 

other metals from natural sources and (or) plumbing despite 

purging in acidic water. Further, concentrations of dissolved 

lead did not appear to be related to the age of the well and the 

inferred age of plumbing nor to the reduction in lead content 

of solder in the 1980s.

Lead data were grouped by geologic unit to determine the 

relation between geology and concentration of dissolved lead 

in groundwater. The highest concentrations of lead generally 

were in samples from quartzites, carbonates, and gneisses 

(in descending order). Concentrations at or above the USEPA 

action level of 15 μg/L were reported for 17 (5 percent) of 

the 331 samples, including water samples from wells drilled 

in the Octoraro Phyllite (15 to 70 μg/L), Chickies Quartzite (15 to 50 μg/L), Setters Quartzite (30 μg/L), Conestoga 

Limestone (24 μg/L), felsic gneiss-granulite facies (24 μg/L), 

Stockton Formation (20 μg/L), Peters Creek Schist (20 μg/L), 

Wissahickon Formation (20 μg/L), Elbrook Limestone 

(20 μg/L), Ledger Dolomite (20 μg/L), and felsic gneiss, 

hornblende-bearing (20 μg/L). Another 22 samples (6.6 percent) that contained 10 to 14 μg/L dissolved lead are mostly 

from these units.

The relation between concentrations of dissolved and 

total lead was investigated on the basis of a limited number 

(20) of groundwater samples that were collected mostly from 

wells (17) in quartzite in 2003 and a few wells (3) in other 

formations in 2001. In these samples, concentrations of dissolved lead generally appear to be greater in samples with a 

pH less than 5 compared to samples with a pH greater than 

6, suggesting that pH is a control on lead in groundwater in 

quartzite aquifers. The highest concentration of total lead 

(19.9 μg/L) was in a sample with a pH of 5.7 that had 1.3 μg/L 

of dissolved lead. The ratio of dissolved to total lead concentrations appears to vary with pH, where for samples with pH 

less than 5, dissolved lead typically equals total lead; with pH 

of 5 to 5.5, ratio of dissolved to total varies widely; with pH 

of 5.5 to 6, dissolved lead represents 60 percent or less of total 

lead (fig. 12). In the one sample with pH greater than 6, dissolved lead represents about 80 percent of total lead.

To clarify preliminary findings from the 2003 samples 

and the unpublished 2004 review, 30 wells in 15 different geologic units were sampled in 2006 for dissolved and total lead 

to provide data for geologic units that were identified in 2004 

as having potential lead problems and on the relation between 

dissolved and total lead. Of the 30 wells sampled in 2006, 

20 wells were previously sampled for dissolved lead. Almost 

all the historical analyses for lead in groundwater in Chester 

County were filtered samples, which yield data on concentrations of dissolved lead. In addition to dissolved and total lead, 

the 2006 samples were analyzed for major ions, nutrients, and 

selected trace elements (arsenic, boron, iron, manganese, and 

uranium). Samples from 10 wells also were analyzed for gross 

alpha-particle and gross beta-particle activities to provide data 

on the relation between lead and radioactivity.

Results of the 2006 sampling suggested that elevated 

dissolved lead concentrations are not frequent countywide 

and included the following observations. Water from only 1 

(3 percent) of 30 wells had concentrations of dissolved and 

(or) total lead greater than the USEPA action level of 15 μg/L. 

The maximum concentration was 18.6 μg/L for dissolved lead 

and 13.3 μg/L for total lead. The difference between concentrations of dissolved and total lead was less than 1 μg/L 

in 22 (73 percent) of the 30 well-water samples. In seven 

of the other eight samples for which the difference between 
Chester County Groundwater-Quality Monitoring Program 37

concentrations of dissolved and total lead was greater than 

1 μg/L, the concentrations of total lead were greater than the 

concentrations of dissolved lead by 1 to 13 μg/L. These results 

indicate that dissolved lead data may underpredict concentrations of total lead in some samples by as much as 13 μg/L. In 

one well-water sample, the reported concentration of dissolved 

lead of 18.6 μg/L was 14.7 μg/L greater than the concentration of total lead, a difference that suggests error in one of 

the analyses or contamination. Concentrations of total lead 

less than the MCL but greater than 7 μg/L (a concentration 

equal to half the USEPA action level that might be used to 

screen for potential problems) were measured in water from 

one well drilled in the Setters Quartzite and one well drilled 

in the Wissahickon Formation; a concentration of dissolved 

lead greater than 7 μg/L was measured in water from one well 

drilled in the Chickies Quartzite.

 In samples collected in 2006 from the 30 wells, concentrations of dissolved copper and dissolved and total lead were 

inversely related to pH; generally, the lower the pH, the higher 

the concentrations of lead and copper. The sample with the 

highest concentration of dissolved lead (18.6 μg/L) had the 

lowest pH (4.6). Concentrations of dissolved copper and lead 

appeared to correlate positively, suggesting a possible plumbing source for these metals. These findings differ slightly from 

the unpublished 2004 review of data; the 2004 review did not 

show a strong relation between pH and concentrations of lead 

and copper. The 2006 findings differ from the unpublished 

2004 review possibly because of differences in accuracy of 

historical trace metal analyses and reported lead concentrations. Water from the 20 wells that were previously sampled 

had concentrations of dissolved lead in 2006 that generally 

were either similar or lower than in previous samples. Concentrations of dissolved lead in 2006 were lower than in previous 

years in water from 10 wells, were similar to previous years 

in water from 9 wells, and were higher than in previous years 

in water from 1 well. The concentrations of dissolved lead 

in samples from the 20 wells collected prior to 2006 ranged 

from the detection level (less than 1 to less than 10 μg/L) to 

50 μg/L. Only one of the five samples from wells that had 

concentrations of dissolved lead above the USEPA action level 

of 15 μg/L prior to 2006 had concentrations of dissolved or 

total lead above 15 μg/L in 2006; this sample had a concentration of 50 μg/L when sampled in 1989 and of 18.6 μg/L when 

sampled in 2006 and was from a well drilled in the Chickies 

Quartzite. Differences in lead concentrations through time 

may be affected by changes in sampling and laboratory methods or household plumbing, as well as by natural variability.

Samples from 3 of 10 wells analyzed in 2006 for 

gross alpha-particle and gross beta-particle activities had 

gross alpha-particle activity greater than the USEPA MCL 

of 15 pCi/L; 2 of the wells were drilled in the Chickies 

Quartzite and 1 well was drilled in the Conestoga Formation 

(carbonate rock). Lead concentrations did not appear to correlate strongly with gross alpha-particle and gross beta-particle 

activities. However, water from one of the Chickies Quartzite 

wells had the highest gross alpha-particle activity (54 pCi/L 

at 30 days) and the highest concentration of dissolved lead 

(18.6 μg/L) of the 30 wells sampled, indicating that lead may 

be produced from radioactive decay of naturally occurring 

aquifer materials and remain mobile (dissolved) in acidic 

groundwater in the quartzite.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

3 3.5 4 4.5 5 5.5 6 6.5 7

pH

RATIO OF DISSOLVED TO TOTAL LEAD CONCENTRATION

Dissolved lead = total lead

Probable error in

laboratory analysis for which dissolved 

lead is greater than total lead 

Figure 12. Relation between pH and the ratio of dissolved to total lead concentrations 

in groundwater samples from 17 wells in the Chickies Quartzite or Antietam and Harpers 

Formation, undivided, Chester County, Pa., 2003.
38 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Overall, the data collected in 2003 and 2006 and the 

unpublished review of lead data in 2004 suggest that relatively 

few (less than 10 percent) wells in the county are likely to 

produce water with lead concentrations greater than the action 

level of 15 μg/L. Elevated lead concentrations may occur 

sporadically and may be related to plumbing (including the 

pump in the well) or naturally occurring lead in the aquifer. 

Some wells in the Chickies Quartzite have elevated concentrations of dissolved lead that appear associated with low pH. 

Some geologic units, including the Chickies Quartzite and 

other quartzites in the county, have naturally occurring low pH 

(acidic) groundwater. Elevated gross alpha-particle activities 

in the water from wells in the Chickies Quartzite also are associated with low pH. Limited data collected in 2003 indicated 

no strong relation between lead-210 derived from radioactive 

decay of radon-222 and measured concentrations of lead in 

well-water samples, although some lead in groundwater may 

be derived from radionuclides in the rock. Lead from natural 

and anthropogenic sources may be mobilized in low pH water 

so that both radium and lead may be present in acidic groundwater in the Chickies Quartzite and geologic units with similar 

composition. However, elevated lead concentrations also may 

occur in water samples from wells in carbonate rocks with pH 

generally close to 7 (neutral pH).

Summary and Conclusions

The groundwater-quality monitoring program conducted 

by the U.S. Geological Survey (USGS) in cooperation with the 

Chester County Water Resources Authority and the Chester 

County Health Department in Chester County, Pa., began in 

1980, partly in response to concerns at the time about possible 

contamination in groundwater that might pose a risk to human 

health. The groundwater-quality monitoring program consists 

of the annual collection of groundwater and occasional stream 

base-flow samples at various sites selected each year. Sample 

selection is done by USGS in consultation with the Chester 

County Water Resources Authority and the Chester County 

Health Department to meet one or more of the following 

objectives: (1) to provide data on groundwater quality near 

suspected sources of contamination; (2) to informally monitor 

groundwater quality near known sources of contamination to 

determine extent of contaminant migration or change in concentration of contaminants; and (3) to provide data on groundwater quality on a regional scale or topical issue, including 

naturally occurring constituents that may pose a health risk. 

The emphasis of the groundwater-quality monitoring program 

primarily has been spatial rather than temporal assessment.

Chester County covers 760 mi2 in southeastern Pennsylvania, and its population relies partly on groundwater for 

drinking-water supply. The rocks underlying Chester County 

form fractured-rock aquifers, where the competent bedrock 

is overlain by weathered bedrock (saprolite) and soil, and 

these aquifers are recharged locally by precipitation. Land use 

in the Chester County is mixed, consisting largely of different types of agriculture (such as row crops, hay, mushroom 

growing and composting, nurseries, orchards, and dairy) with 

lesser amounts of wooded, residential, industrial, commercial, 

and other uses. On-site wastewater disposal and individual 

wells for water supply are common. Most wells sampled for 

the groundwater monitoring program were residential wells, 

although some public supply, industrial, commercial, and 

monitor wells were also sampled.

Generally, chemical constituents associated with various 

land uses and human activities were measured in groundwater 

near those areas in Chester County. Results of the groundwater-quality monitoring program included:

• Volatile organic compounds (VOCs) were detected 

near some uncontrolled landfills, dumps, and industrial 

waste-disposal activities. Trichloroethylene (TCE) was 

the most frequently detected VOC. Concentrations of 

TCE also exceeded the Maximum Contaminant Level 

(MCL) in drinking water most frequently and were at 

or above the MCL of 5 μg/L in samples from 47 of 412 

wells sampled from 1980 through 2001. The highest 

measured TCE concentration was 4,400 μg/L. Concentrations of several other VOCs exceeded MCLs established for those compounds in samples from fewer than 

47 wells sampled as part of the monitoring program.

• Elevated concentrations of ammonia, iron, and manganese were measured in groundwater and stream base 

flow near some uncontrolled dumps and landfills.

• Concentrations of chloride (up to 350 mg/L) substantially above the estimated natural background concentration of 10 mg/L were measured in groundwater 

near salt piles and the Pennsylvania Turnpike and are 

related to the use of deicing salts on roads.

• Formaldehyde in concentrations above drinking-water 

health advisories of 1 mg/L were measured in groundwater near cemeteries.

• Pesticides and elevated concentrations of nitrate (up to 

45 mg/L as N) were detected in groundwater and base 

flow in some agricultural areas of the county, including 

near row crops, orchards, nurseries, and mushroomgrowing operations. Samples from the Octoraro Creek 

Basin showed that relatively high concentrations of 

nitrate and some pesticides such as atrazine in base 

flow occur where high concentrations of these constituents were found in groundwater.

• In areas where the relation between groundwater and 

surface-water quality were investigated, base-flow 

samples indicated that groundwater discharge to 

streams carries contaminants such as nitrate, pesticides, 

chloride, and wastewater compounds. Conversely, in 

streams with losing reaches, contaminants in surface 

water may enter the groundwater system.
Summary and Conclusions 39

• Moderately elevated concentrations (compared to 

estimated natural background) of nitrate (commonly 

3–6 mg/L as N), chloride, and boron and relatively 

low concentrations of VOCs and other anthropogenic 

wastewater compounds, including pharmaceuticals, 

were measured in groundwater and base flow in areas 

with residential on-site wastewater disposal, indicating 

that constituents from wastewater affect the quality of 

groundwater and stream base flow.

• At least half of the sampled wells in the county had 

chloride concentrations above the natural background 

level of about 10 mg/L. Chloride concentrations 

greater than the SMCL of 250 mg/L were measured 

in samples from 5 wells and were up to 2,100 mg/L. 

Sources of chloride included deicing salts on roads and 

on-site wastewater disposal.

• Trends in groundwater quality estimated from baseflow samples and from review of well-water samples 

indicated that chloride concentrations have been 

increasing in groundwater and base flow through 

time since the 1960s as urbanization of the county 

increased. Other effects of urbanization, such as introduction of other chemicals used at the land surface in 

urban areas (such as VOCs), on groundwater quality 

are possible and have been documented through the 

program.

Data on naturally occurring constituents in groundwater that may pose a risk to human health were also collected 

through the groundwater-quality monitoring program. These 

naturally occurring constituents are derived mainly from rocks 

and soils that form the fractured-rock aquifers in the county. 

Chester County has relatively complex geology, with about 

40 different mapped bedrock units consisting of Paleozoicage and older metamorphic rocks, including phyllite, schist, 

limestone, marble, quartzite, and gneiss, and Mesozoic-age 

sedimentary (Triassic age) and intrusive (Triassic- and Jurassic-age) rocks. The naturally occurring constituents in groundwater in Chester County that may be of concern include:

• Radionuclides—radium-226, radium-228, radium-224, 

gross alpha-particle activity–especially in groundwater 

from quartzite aquifers with low pH–and radon-222 in 

many geologic units throughout the county.

• Arsenic, especially in groundwater from shales and 

other Triassic-age rocks in northern Chester County.

• Lead in low pH water.

Activities of radium-226, radium-228, and gross alpha 

particles were measured in reconnaissance sampling of 

geologic units in the county from 1985 through 1987. Subsequent studies by USGS in cooperation with state agencies 

showed that 62 percent of well-water samples in the Chickies 

Quartzite had combined radium-226 plus radium-228 activities greater than the USEPA MCL of 5 pCi/L. Elevated radium 

and gross alpha-particle activities are associated with low pH 

in groundwater in the Chickies Quartzite. Elevated radium 

activities were also found in groundwater in other Paleozoicage quartzites and occasionally in other geologic units, including limestones, in the county. Follow-up sampling in 1999 

and 2003–06 confirmed earlier findings of elevated radium 

and gross alpha-particle activities in the Chickies Quartzite 

and also identified the presence of other short-lived radionuclides radium-224 and lead-210. The radium-224 activity of 

265 pCi/L measured in a well-water sample collected in 1999 

in Chester County is one of the highest reported in the United 

States. The difference between the gross alpha-particle activity 

at 72 hours and 30 days measured in 18 samples ranged up 

to a factor of 7 and showed that short-lived radionuclides are 

present in groundwater. The use of gross alpha-particle activity measurements at 30 days may be insufficient to monitor 

potential exceedances of MCLs in some settings.

Radon-222 activities above the higher proposed MCL 

of 4,000 pCi/L occurred in about 18 percent of 605 wells 

sampled throughout the county from 1986 through 2000 and 

were most common in samples from wells in the Peters Creek 

Schist. Water samples collected monthly for radium and radon 

analysis showed seasonal fluctuations that indicate drinkingwater standards in groundwater could be exceeded seasonally 

but might not be detected if the well were not sampled during 

the time of year when maximum concentrations occur.

Arsenic concentrations greater than the MCL of 10 μg/L 

have been measured in only a few wells in the county, but 

higher concentrations of arsenic are more common in the 

Triassic-age geologic units (mostly shales and sandstones) 

than elsewhere in the county. Other studies estimate that about 

10 percent of the wells in similar rocks in nearby Bucks and 

Montgomery Counties have water with arsenic concentrations greater than 10 μg/L. Concentrations of arsenic greater 

than the health advisory level of 2 μg/L were present in about 

40 percent of the well-water samples in the Triassic geologic 

units and in about 10 percent or less of well-water samples in 

other geologic units in Chester County.

Other potential natural hazards, such as lead, were 

measured infrequently in concentrations in well water above 

drinking-water standards (less than 10 percent of samples). 

Some lead may occur naturally, although lead also may have 

anthropogenic sources in plumbing. Lead from either source 

may be more soluble in some types of water. In the relatively 

acidic groundwater in quartzite, lead concentrations appear to 

increase with a decrease in pH.

Through the Chester County groundwater-quality monitoring program, groundwater contamination from localized 

targeted sources was identified and data on the effects of some 

land uses, including residential on-site wastewater disposal, on 

groundwater and base-flow quality were collected. Although 

the primary focus of the monitoring program was spatial 

assessment of groundwater-quality issues and concerns, the 

data collected through the program may serve as a baseline 

for future comparison. Additional analysis or collection of 

groundwater-quality data may be helpful in determining 

specific land-use or geochemical factors affecting groundwater 

quality spatially or through time.
40 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

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data Pennsylvania water year 2000, volume 2. Susquehanna 

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Pennsylvania water year 2001, volume 1. Delaware River 

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529 p.

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Pennsylvania water year 2002, volume 1. Delaware River 

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527 p.

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651 p.
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Durlin, R.R., Schaffstall, W.P., and Beaver, M.R., 2006, Water 

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Water-Supply Paper 2254, 263 p.

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Microbiological quality of water from noncommunity 

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Pennsylvania: U.S. Geological Survey Water-Resources 

Investigations Report 01–4268, 30 p.

Ludlow, R.A., and Loper, C.A., 2004, Chester County groundwater atlas, Chester County, Pennsylvania: U.S. Geological 

Survey Open-File Report 03–442, 85 p.

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05–05.0, 6 p., Portable Document Format (PDF).

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Geological Survey Scientific Investigations Report 2009–

5086, 41 p.

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trends in biological and water-chemistry data from selected 

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Geological Survey Water-Resources Investigations Report 

02–4242, 77 p.

Reif, A.G., 2002b, Assessment of stream conditions using 

biological indices at selected sites the Big Elk and Octoraro 

Creek Basins, Chester County, Pennsylvania, 1981–97: 

U.S. Geological Survey Water-Resources Fact Sheet 

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and O’Brien, D.L., 2005, Effects of spray-irrigated treated 

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hydrogeology, land use, and surface-water quality in the 

Red Clay Creek Basin, Piedmont Physiographic Province, 

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Water-Resources Investigations Report 96–4288, 122 p.

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Geological Survey Open-File Report 2007–1253, 50 p.

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Geological Survey Water-Resources Investigations Report 

03–4193, 144 p.

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activities in groundwater from the rocks of the Piedmont 

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no. 1, p. 73.
42 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

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2006–5261, 105 p.

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60 p.

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groundwater of southeastern Pennsylvania: U.S. Geological 

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Mustang Superfund site, Chester County, Pennsylvania: 

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Wiswall, C.G., 2005, Bedrock geologic map of the Unionville 

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05–03.0, 15 p., Portable Document Format (PDF).

Appendix 1.
46 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

ELK

WARWICK

WEST CALN

KENNETT

HONEY BROOK

PENN

HIGHLAND

CALN

TREDYFFRIN

NEWLIN

WILLISTOWN

FRANKLIN

WALLACE

NEW GARDEN

WEST VINCENT

LOWER OXFORD

LONDON GROVE

WEST BRADFORD

UPPER OXFORD

EAST NOTTINGHAM

UWCHLAN

EAST NANTMEAL

EAST VINCENT

WEST FALLOWFIELD

EAST BRADFORD

NEW LONDON

PENNSBURY

CHARLESTOWN

WEST GOSHEN

EAST FALLOWFIELD

WEST NANTMEAL

WEST MARLBOROUGH

LONDONDERRY

NORTH COVENTRY

WESTTOWN

EASTTOWN

SCHUYLKILL

VALLEY

POCOPSON

WEST WHITELAND

EAST MARLBOROUGH

WEST NOTTINGHAM

EAST GOSHEN

UPPER UWCHLAN

WEST BRANDYWINE

EAST COVENTRY

EAST WHITELAND

WEST PIKELAND

WEST SADSBURY

EAST BRANDYWINE

LONDON BRITAIN

EAST PIKELAND

SADSBURY

BIRMINGHAM

SOUTH COVENTRY

EAST CALN

THORNBURY

PHOENIXVILLE

OXFORD

DOWNINGTOWN

COATESVILLE

MALVERN

WEST CHESTER

ATGLEN

ELVERSON

PARKESBURG

SPRING CITY

VALLEY

KENNETT SQUARE

WEST GROVE

MODENA

HONEY BROOK

AVONDALE

SOUTH COATESVILLE

76° 75°50' 75°40' 75°30'

39°40'

39°50'

40°

40°10'

EXPLANATION

Municipality

0

0

5

5

10

10

MILES

KILOMETERS

Figure 1–1. Municipalities in Chester County, Pa.
Appendix 1 47

Figure 1–2. Location of wells and surface-water sites sampled for the Chester County groundwater-quality monitoring program, 

(A) 1980–84, (B) 1985–89, (C) 1990–94, (D) 1995–1999, (E) 2000–04, and (F) 2005–2008.

2470

31

69

812

165,154 155

151,152

307

251

2802

2801

2800

2753

2752

2751

2750

2749

2748

2681

2679

2678

2677

2676

2664

2136,2676,2613

2549

2545 2535

2469

2143 2089

1976,2411,2402,2494

1231

2507

2506

2504

2503

2501

2500

2498

2497

2495

2489

2488

2486

2478

2461

2451

2419

2198

2197 1613

1600

2491

2476

2475

2474

2473

2472

2471

2467

2466

2465

2463

2460 2462

2459

2452

2449

2447

2442

2426

2412

2061

1935

1201

2450

2444

2443 2441

2439 2440

207

2437

2436

2435

2434

2433

2432

2431

2430

2428

2427

2425

2424

2423

2421

2420

2417

2414

2408 2401

1726

1366

2418

2416

2415

2413

2406

2405

2404

2403 2348

2505

2339

2453

2502 2499

2046 2468

2422

2496 2477 1978

2448,1969

2445

1983 1973

2479

1585 2680

164 2464

2507

2149

2153

249,2148

45

2803

2165

206

2429 1315

2438

2199

76°00' 75°50' 75°40' 75°30'

40°10'

40°

39°50'

39°40'

EXPLANATION

Well and local well number

Municipality

0

0

5

5

10

10

MILES

KILOMETERS

A
48 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

69

86 88

84

83

82

81

71

848

989

204

889

991

412

410

1985

744

3623 3622

3621

3551

3540

3539,3318 3478

2469,3304,3475,3295.3000

3474 3129, 3473

3472

3470

3467

3365

3364

3363

3361

3358

3357,3359

3356

3079

2745

2677

2586

2315

2197,3355,3360,3112

3324

3323

3322 3317 3320 3316

3309

3307

3306

3303

3302

3300

3299

3298

3297

3296

2562

2569,3289,3291

3275

3227

2840

2663

2634

2506

2474

2443

2437

2348

2161

3213 3136

3133

3130

3121

3120 3119

3118

3116

3115

3110

3108

3107

3106

3105 3103

3100

3092

3085

3083

3082

3081

3080

3077

2999

2998

2828

2766

2465

2430

2062

1727

1501

1496

1099 1483

1097

3219

3073

2746

2555

2505

2482

2415

2403 2308

2293

2271

2138

2084

1981

1954

1627 1613

1547

1528

1435

1370

1361

1299

1074

2845

2806

2678

2675

2673

2444

2421

1201

1000

992 3048 2476

3314

2015 3313

3084, 3293,3409

3312, 3468,3310,3458

2591

3308

3321

3471

2714

2436

2743

3362

2674

2846 2740

2535 2543 3076

1364,

1499

3099

1564

1567

1565

1593

2805 2804

2448

2549

2199,207,2672,2541 2553

386

3078,2606,2605,Glasgow quarry

2411,2494

2574,2671

2611,2676, 

Warner quarry

2678

Glasgow quarry

2807

206

2429

85,87

249

76°00' 75°50' 75°40' 75°30'

40°10'

40°

39°50'

39°40'

0

0

5

5

10

10

MILES

KILOMETERS

EXPLANATION

Surface-water site and site name

Well and local well number

Municipality

B

Figure 1–2. Location of wells and surface-water sites sampled for the Chester County groundwater-quality monitoring program, 

(A) 1980–84, (B) 1985–89, (C) 1990–94, (D) 1995–99, (E) 2000–04, and (F) 2005–08.—Continued
Appendix 1 49

Figure 1–2. Location of wells and surface-water sites sampled for the Chester County groundwater-quality monitoring program, 

(A) 1980–84, (B) 1985–89, (C) 1990–94, (D) 1995–99, (E) 2000–04, and (F) 2005–08.—Continued

SP44

3624,SP43

SP41

71

509,3932,3627

307

895

5091

5090

5089

5088

5087

4809

4808 4806,4126,4297,4501

4805

4804

4803

4802

4801

4730

4345

3516

3484

3430

3384

2543 2402

2317

4553

4552

4551

4550

4547

4546

4500

2161,4293,4292,4499,2725

4498

4497

4496

4495

4493

4491

4411

4409

4344

3859

3150

2728

2719

1978

1720

1599

4343

4342

4341

4299

4298

4296

4295 4294

4291

4278

4277

4276

4275

4274

4273

4272

4271

4006,4009,4128,4270

4148

3335

2969

2279

1617

4129

4127

4125

4124

4123

4122

4121

4120

4119

4118

4026

3841

3561

2755

2723

2451

1765

1761

1737

1709

1703

1659

1651

4025

4022

4010

4008

4007

4004

3838

3837

3758

3673

3657

3655

3613

3316

2777

2752

3640 4502

3272

2611

1985 SP48

SP49

SP42

2746

2742,3296

2724

4024

3310

4023 3482

3445,4005

4807

3625

SP44

1761

2186

4548

4549

1315

2189

76°00' 75°50' 75°40' 75°30'

40°10'

40°

39°50'

39°40'

EXPLANATION

Spring and local spring number

Municipality

Well and local well number 0

0

5

5

10

10

MILES

KILOMETERS

C
50 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Figure 1–2. Location of wells and surface-water sites sampled for the Chester County groundwater-quality monitoring program, 

(A) 1980–84, (B) 1985–89, (C) 1990–94, (D) 1995–99, (E) 2000–04, and (F) 2005–08.—Continued

30

992

432

245 204

202

5364

3331 3334

3330

3136

3119

3117

3115

2769

2766

2161

1985

1616

5244

5243

5160

4828

4817

2311

5563

5562

5561

5560

5559

5558

5557

5556

5555

5554

5553

4573

1281

5481

5480

5479

5478

5477

5476

5475

5474

5473

5472

5470

5469

4815

4261

3184

2574 2560

2033

1110

5272

5270

5269

5260 5261

5259

5229

5227

5225

5223

5222

5220

4779

4778 4772

4771

4770

4769

4768

4767

4539

4339

4133

3859

2676

2497

2461

5226

5471

5221

5228

5238

5223

76°50' 75°50' 75°40' 75°30'

40°10'

40°

39°50'

39°40'

EXPLANATION

Well and local well number

Municipality

0

0

5

5

10

10

MILES

KILOMETERS

D
Appendix 1 51

Figure 1–2. Location of wells and surface-water sites sampled for the Chester County groundwater-quality monitoring program, 

(A) 1980–84, (B) 1985–89, (C) 1990–94, (D) 1995–99, (E) 2000–04, and (F) 2005–08.—Continued

86

992

410

543

6824

6647

6646

6644

6643

6517

6515

6514

3995

3327

3125

2570

1616

6656

6655

6654

6653

5178

6496

6407 6408

6406

6405

6404

6403

6402

6401

6400

6399

5998

5997

5996

5995

5703

5680

1730

1435 1283

5938

5937

5922

5921

5920

5593

5450

5377

5365

5266

5230

4730

4420

3516 4413

3331

1757

1743

1735

1710

1705

1680

1667

1664

1652

1281

1037

4771

6535

4884

5450

75

01578469

01578466

01578457

01578352

01578379

01578343

015783479

01578352

76°50' 75°50' 75°40' 75°30'

40°10'

40°

39°50'

39°40'

E

0

0

5

5

10

10

MILES

KILOMETERS

EXPLANATION

Surface-water site and site number

Well and local well number

Municipality
52 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Figure 1–2. Location of wells and surface-water sites sampled for the Chester County groundwater-quality monitoring program, 

(A) 1980–84, (B) 1985–89, (C) 1990–94, (D) 1995–99, (E) 2000–04, and (F) 2005–08.—Continued

83

SP71

SP70

5445

5444

5435

4261 4230

7236

7220

7268

7267

7266

6538

5457

5221

4817

4505

4294

4195

4155

3918

3365

3334

3302

3300

3117

3077

2766

2725

2433

2421

2021

1978 1985

1801

1613

1483

6882

6881,755

6880

6673,01480637

6879

014806374

014806384

EXPLANATION

Surface-water site and site number

Well and local well number

Municipality

Spring and local spring number

014806384

SP71

2021

2189

01480457 01480160

01478147

01476420

01480750

01480662

01480656

01472110

01472080

014806775

014806215

014806394

0148063532,0148063528

0148063522

01480739,01480742,01480743,014807434

014807438,01480744,014807447,01480745

014806366,014806368

01480913,6883

76°00' 75°50' 75°40' 75°30'

40°10'

40°

39°50'

39°40'

F

0

0

5

5

10

10

MILES

KILOMETERS
Appendix 1 53

Table 1-1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.

[Municipalities are shown on figure 1.1, and locations of wells and streams are shown on figure 1-2]

Abbreviations—

Local well number: CH-, where prefix CH designates Chester County; SP designates spring;

Gunit, geologic unit code:

000ANRS anorthosite

000GRGS granite gneiss

000MFCGH mafic gneiss, amphibolite facies

000MFCGP mafic gneiss, granulite facies

000PGMT pegmatite

000QZMZ quartz monzonite and quartz monzonite gneiss

000SRPN serpentinite

112ALVM alluvium

231BRCK Brunswick Group

231DIBS diabase

231HMCK Hammer Creek Formation

231LCKG Lockatong Formation

231SCKN Stockton Formation

300CCKV Cockeysville Marble

300PRCK Peters Creek Schist

300STRS Setters Quartzite

300WSCK Wissahickon Formation

300WSCKA Octoraro Formation

300WSCKO Wissahickon Formation

367CNSG Conestoga Limestome

371ELBK Elbrook Limestone

377AMHP Anietam/Harpers, undifferntiated

377ANTM Antietam Formation

377CCKS Chickies Quartzite

377HLLM Hellam Conglomerate

377HRPR Harpers Formation

377KZRS Kinzers Limestone

377LDGR Ledger Dolomite

377VNTG Vintage Dolomite

400BMFGA banded mafic gneiss, amphibolite facies

400FCIGA felsic and intermediate gneiss, amphibolite facies

400FLCGA felsic gneiss, amphibolite facies

400FLCGG felsic gneiss, granulite facies

400FLCGH felsic gneiss, amphibolite facies

400FLCGP felsic gneiss, granulite facies

400FMFG felsic and mafic gneiss

400GPCGA graphitic felsic gneiss, amphibolite facies

400GPCGG graphitic felsic gneiss, granulite facies

400MFCGH mafic gneiss, amphibolite facies

Reason sampled: DU, dump or landfill; IPT, industry or localized (point) source; LU, land use; NA, natural

Man-made organic compound: x indicates man-made organic compound detected; MCL or HA, maximum contaminant level or health advisory for drinking 

water exceeded for constituent by category, where m indicates MCL exceeded and h indicates HA exceeded: (Note that row is shaded green if MCL or HA 

exceeded); VOC, volatile organic compound or other industrial compound; Pesticide, herbicide or insecticide; Nutrient, nitrate or nitrite; Metal, metal or other 

inorganic ion; Radchem, any radiochemical constituent except radon-222
54 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1980 69 395019075431501 Kennett 300CCKV DU x

1980 1983 400326075323201 East Whiteland 371ELBK DU

1980 2348 400008075401001 East Caln 377LDGR DU m h

1980 2401 395623075454901 Newlin 300PRCK DU

1980 2402 400313075315001 East Whiteland 377LDGR DU

1980 2403 395936075542501 West Caln 377CCKS DU

1980 2404 395639075462601 Newlin 300PRCK DU

1980 2405 400428075405701 Upper Uwchlan 400GPCGA DU

1980 2406 400109075543201 West Caln 377CCKS DU x

1980 2411 400329075315501 East Whiteland 377LDGR DU

1980 2412 400129075365901 West Whiteland 367CNSG IPT

1980 2413 395435075430601 Newlin 000SRPN DU

1980 2414 395037075433201 New Garden 300CCKV DU x

1980 2415 395731075485201 South Coatesville 300PRCK DU

1980 2416 395940075493701 Valley 400FCIGA DU x m

1980 2417 400117075541501 West Caln 377CCKS DU

1980 2418 400340075501201 West Brandywine 377CCKS DU

1980 2419 400712075550001 Honey Brook 377HLLM DU x h
Appendix 1 55

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1981 69 395019075431501 Kennett 300CCKV DU

1981 251 400421075315301 East Whiteland 377LDGR IPT x m

1981 293 400422075312801 Tredyffrin 377CCKS IPT x m

1981 307 400124075374101 West Whiteland 367CNSG IPT x m

1981 1366 400259075524001 West Caln 377CCKS DU

1981 1585 400740075343901 East Pikeland 400GPCGG IPT x m

1981 1726 395120075583301 Upper Oxford 300PRCK NULL x m

1981 2046 395814075353001 West Goshen 400FLCGP IPT x m

1981 2136 400409075304901 Tredyffrin 371ELBK IPT x m

1981 2143 400210075350901 East Whiteland 367CNSG IPT

1981 2348 400008075401001 East Caln 377LDGR DU

1981 2401 395623075454901 Newlin 300PRCK DU

1981 2406 400109075543201 West Caln 377CCKS DU x m

1981 2408 395521075573001 West Fallowfield 300WSCKA

1981 2411 400329075315501 East Whiteland 377LDGR DU x

1981 2414 395037075433201 New Garden 300CCKV DU

1981 2417 400117075541501 West Caln 377CCKS DU

1981 2420 395814075584901 West Sadsbury 400FMFG NULL

1981 2421 395322075561701 West Fallowfield 300PRCK NULL x m

1981 2422 400130075362301 West Whiteland 367CNSG DU

1981 2423 400219075533701 West Caln 377CCKS DU

1981 2424 395744075473901 East Fallowfield 300WSCKA IPT

1981 2425 400335075374401 Uwchlan 400FCIGA DU x m

1981 2426 401015075321401 Spring City Borough 231BRCK IPT

1981 2427 400918075361901 East Vincent 231SCKN DU

1981 2428 400427075411501 Upper Uwchlan 400GPCGA IPT

1981 2429 400227075431201 East Brandywine 377CCKS IPT

1981 2430 395812075403401 West Bradford 300WSCKO IPT

1981 2431 395727075541201 Sadsbury 367CNSG IPT

1981 2432 400221075321201 East Whiteland 300WSCKO IPT

1981 2433 400620075563801 Honey Brook 377CCKS DU

1981 2434 401221075353601 East Coventry 231BRCK IPT x

1981 2435 401210075351501 East Coventry 231BRCK IPT x m

1981 2436 400313075365501 West Pikeland 377CCKS IPT

1981 2437 394740075434201 New Garden 300WSCKO DU x m

1981 2438 400331075342401 East Whiteland 377LDGR IPT x m

1981 2439 394626075584901 East Nottingham 300WSCKO IPT

1981 2440 394607075385601 East Nottingham 300WSCKO DU

1981 2441 400625075391501 West Vincent 400GPCGA IPT

1981 2442 400601075503501 West Nantmeal 000ANRS DU

1981 2443 400654075282401 Schuylkill 231SCKN IPT

1981 2444 400243075292501 Tredyffrin 300WSCKA IPT x

1981 2445 400254075295801 Willistown 300WSCKA IPT x m

1981 2447 400533075412901 Upper Uwchlan 400GPCGA IPT

1981 2448 400258075311001 East Whiteland 367CNSG IPT x m m

1981 2449 400658075325401 Charlestown 231SCKN IPT x m

1981 2450 395439075375301 Pocopson 300WSCKO IPT x m

1981 2451 395727075414901 West Bradford 300WSCKO IPT x m

1981 2452 395815075421401 West Bradford 300WSCKA IPT x

1981 2453 395847075375201 West Goshen 300WSCKO DU
56 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1982 45 395215075420901 East Marlborough 300CCKV DU

1982 151 400806075310501 Phoenixville Borough 231SCKN IPT

1982 152 400805075304801 Phoenixville Borough 231SCKN IPT

1982 154 400750075312901 Phoenixville Borough 231SCKN IPT h

1982 1201 395701075561601 West Sadsbury 367CNSG IPT m

1982 1935 395812075502901 East Fallowfield 300WSCKA IPT

1982 2061 395203075451401 East Marlborough 300STRS IPT x

1982 2136 400409075304901 Tredyffrin 371ELBK IPT x

1982 2411 400329075315501 East Whiteland 377LDGR DU

1982 2412 400129075365901 West Whiteland 367CNSG IPT x

1982 2426 401015075321401 Spring City Borough 231BRCK IPT

1982 2433 400620075563801 Honey Brook 377CCKS IPT

1982 2442 400601075503501 West Nantmeal 000ANRS DU

1982 2443 400654075282401 Schuylkill 231SCKN IPT

1982 2444 400243075292501 Tredyffrin 300WSCKA IPT

1982 2447 400533075412901 Upper Uwchlan 400GPCGA IPT

1982 2448 400258075311001 East Whiteland 367CNSG IPT h

1982 2449 400658075325401 Charlestown 231SCKN IPT

1982 2452 395815075421401 West Bradford 300WSCKA IPT

1982 2453 395847075375201 West Goshen 300WSCKO DU h

1982 2459 394800075563801 Lower Oxford 300WSCKO DU

1982 2460 394635075590101 East Nottingham 300WSCKO IPT

1982 2461 394940075525901 Penn 300WSCKO LU

1982 2462 394639075453701 New Garden 000MFCGH IPT

1982 2463 400848075314901 East Pikeland 231LCKG IPT h

1982 2464 400758075322001 Schuylkill 231SCKN IPT

1982 2465 400930075321201 East Pikeland 231LCKG LU x m

1982 2466 400436075291701 Tredyffrin 377LDGR IPT

1982 2467 395900075381001 West Goshen 300WSCKO DU

1982 2468 395803075353701 West Chester 400FLCGP IPT

1982 2468 395803075353701 West Chester Borough 400FLCGP IPT x

1982 2469 400815075342801 East Pikeland 231SCKN DU

1982 2470 400653075330001 Charlestown 231SCKN IPT x

1982 2471 400651075345201 East Pikeland 400GPCGA DU x

1982 2472 395934075543201 West Caln 377CCKS DU

1982 2473 400707075545001 Honey Brook 400FLCGG DU x

1982 2474 395744075480501 Modena Borough 300WSCKA IPT

1982 2475 395449075375201 Pocopson 300WSCKO IPT

1982 2476 395828075505001 Valley 367CNSG IPT

1982 2477 400153075361501 West Whiteland 367CNSG IPT x m

1982 2478 400430075325701 Charlestown 377CCKS IPT x m

1982 2479 400420075083501 Tredyffrin 377LDGR IPT
Appendix 1 57

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1983 31 395030075425801 Kennett Square 300CCKV IPT x m

1983 155 400733075320401 Phoenixville Borough 231SCKN IPT

1983 164 400827075311501 Phoenixville Borough 231LCKG IPT

1983 165 400755075314301 Phoenixville Borough 231SCKN IPT

1983 206 400555075413901 Upper Uwchlan 400GPCGA LU x

1983 1315 400205075372301 West Whiteland 377LDGR IPT

1983 1600 400449075392501 West Pikeland 400GPCGA LU

1983 1613 400536075381501 West Pikeland 400GPCGA LU

1983 1969 400248075310201 East Whiteland 367CNSG IPT x

1983 1978 400231075334701 East Whiteland 371ELBK LU x

1983 2046 395814075353001 West Goshen 400FLCGP IPT x m

1983 2149 401145075343801 East Vincent 231BRCK IPT

1983 2153 400655075351701 East Pikeland 400GPCGA IPT

1983 2197 400512075291001 Schuylkill 377CCKS IPT

1983 2198 400326075290101 Tredyffrin 371ELBK IPT

1983 2339 395808075365501 West Chester Borough 400FLCGH LU

1983 2411 400329075315501 East Whiteland 377LDGR DU

1983 2419 400712075550001 Honey Brook 377HLLM DU x m

1983 2451 395727075414901 West Bradford 300WSCKO IPT

1983 2461 394940075525901 Penn 300WSCKO LU x

1983 2469 400815075342801 East Pikeland 231SCKN DU x

1983 2473 400707075545001 Honey Brook 400FLCGG DU x

1983 2478 400430075325701 Charlestown 377CCKS IPT x m

1983 2486 400624075331701 Charlestown 400GPCGA IPT

1983 2488 400448075391401 West Pikeland 400GPCGA LU

1983 2489 400544075372601 West Pikeland 400GPCGA LU

1983 2494 400334075313801 East Whiteland 377LDGR DU

1983 2495 400117075361101 West Whiteland 300WSCKA IPT

1983 2496 400145075363801 West Whiteland 367CNSG IPT x m

1983 2497 400136075385501 West Whiteland 377LDGR IPT

1983 2498 395834075352701 West Goshen 400FLCGP IPT x m

1983 2499 395739075351301 West Goshen 400FLCGP IPT

1983 2500 400617075562301 Honey Brook 400FLCGG DU

1983 2501 400632075562401 Honey Brook 377CCKS DU

1983 2502 395705075334701 West Goshen 400FLCGH LU

1983 2503 395447075410701 Pocopson 400FLCGH LU x

1983 2504 395826075504001 Valley 367CNSG IPT

1983 2505 395707075441401 West Bradford 300PRCK IPT x m

1983 2506 395632075453901 Newlin 300PRCK DU

1983 2507 395359075581101 West Fallowfield 300PRCK IPT x
58 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1984 31 395030075425801 Kennett Square 300CCKV IPT x m

1984 69 395019075431501 Kennett 300CCKV IPT

1984 207 400247075335001 East Whiteland 377LDGR IPT x m

1984 812 395433075431601 Newlin 000SRPN DU

1984 1231 400439075403301 Upper Uwchlan 400GPCGA LU

1984 1973 400343075305901 Tredyffrin 371ELBK IPT

1984 1976 400331075320701 East Whiteland 377LDGR IPT x

1984 1978 400231075334701 East Whiteland 371ELBK LU

1984 2089 400213075310801 Malvern Borough 300WSCKA IPT x

1984 2143 400210075350901 East Whiteland 367CNSG IPT

1984 2148 400351075311001 Tredyffrin 371ELBK IPT

1984 2165 394910075491301 London Grove 300CCKV IPT

1984 2199 400313075341301 East Whiteland 377LDGR IPT x

1984 2429 400227075431201 East Brandywine 377CCKS DU, NA x m m

1984 2469 400815075342801 East Pikeland 231SCKN DU x

1984 2535 400231075344901 East Whiteland 377LDGR IPT h

1984 2545 400234075343101 East Whiteland 377LDGR IPT

1984 2549 400350075334201 East Whiteland 371ELBK IPT

1984 2613 400402075304101 Tredyffrin 371ELBK IPT

1984 2664 400255075261701 Easttown 300WSCKA IPT

1984 2676 400402075304701 Tredyffrin 371ELBK IPT x m

1984 2677 400356075295201 Tredyffrin 371ELBK IPT

1984 2678 394609075590101 East Nottingham 300WSCKO IPT

1984 2679 395159075504201 London Grove 300WSCKO DU

1984 2680 400738075331501 East Pikeland 231SCKN IPT

1984 2681 400712075332801 East Pikeland 231SCKN IPT

1984 2748 395631075343701 West Goshen 400FLCGH IPT

1984 2749 400223075321901 East Whiteland 300WSCKA IPT

1984 2750 395725075352001 West Goshen 400FLCGP IPT

1984 2751 405649075344001 West Goshen 400FLCGH DU

1984 2752 395753075374201 East Bradford 400FLCGH IPT x

1984 2753 400038075401101 East Caln 377LDGR DU

1984 2800 400337075495601 West Brandywine 377CCKS DU

1984 2801 395732075352701 Westtown 400FLCGP IPT x

1984 2802 395728075352501 Westtown 400FLCGP IPT

1984 2803 394410076010001 West Nottingham 000SRPN IPT

1984 400412075311001 Valley Creek tributary 

below Warner quarry

IPT
Appendix 1 59

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1985 400407075314801 Warner Quarry floor IPT x m

1985 400412075314701 Warner Quarry waterfall IPT x m

1985 400415075312801 Warner Quarry discharge IPT x m

1985 400412075311001 Warner Quarry below 

settling pond

IPT x m

1985 400406075324401 Glasgow Quarry 1 IPT x m

1985 400356075324101 Glasgow Quarry 2 IPT x m

1985 400413075322801 Glasgow Quarry 3 IPT x m

1985 207 400247075335001 East Whiteland 377LDGR IPT x m

1985 744 395734075392201 East Bradford 300WSCKO IPT x

1985 991 395810075534301 Sadsbury 377CCKS NA

1985 1074 395703075585001 Atglen Borough 377HRPR IPT h

1985 1201 395701075561601 West Sadsbury 367CNSG IPT

1985 1364 400241075535201 West Caln 377CCKS NA m

1985 2197 400512075291001 Schuylkill 377CCKS NA m

1985 2403 395936075542501 West Caln 377CCKS IPT x

1985 2421 395322075561701 West Fallowfield 300PRCK NA x m

1985 2429 400227075431201 East Brandywine 377CCKS DU x m

1985 2436 400313075365501 West Pikeland 377CCKS NA m

1985 2444 400243075292501 Tredyffrin 300WSCKA IPT x

1985 2476 395828075505001 Valley 367CNSG IPT

1985 2535 400231075344901 East Whiteland 377LDGR IPT x h

1985 2549 400350075334201 East Whiteland 371ELBK IPT x m

1985 2553 400419075330301 East Whiteland 371ELBK IPT x m

1985 2562 400428075315101 East Whiteland 371ELBK LU

1985 2569 400402075312901 Tredyffrin 371ELBK IPT

1985 2574 400423075310101 Tredyffrin 377LDGR LU

1985 2606 400415075321501 East Whiteland 377LDGR IPT x m

1985 2671 400426075304001 Tredyffrin 377LDGR LU

1985 2672 400313075340301 East Whiteland 371ELBK IPT x m

1985 2673 394630075585101 East Nottingham 300WSCKO IPT

1985 2674 400147075363101 West Whiteland 367CNSG IPT

1985 2675 395007075474101 London Grove 300CCKV LU

1985 2678 394609075590101 East Nottingham 300WSCKO IPT

1985 2769 395131075503401 London Grove 300STRS NA m

1985 2804 400623075310501 Charlestown 400FCIGA NA

1985 2805 400622075310101 Charlestown 400FCIGA NA

1985 2806 400010075465401 Caln 400FCIGA IPT

1985 2807 400441075451001 Wallace 377CCKS IPT

1985 2845 400653075554301 Honey Brook 377CCKS DU

1985 2846 400151075360601 West Whiteland 367CNSG DU
60 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1986 71 395017075433801 New Garden 300CCKV LU m

1986 75 394735075580901 Oxford Borough 300WSCKO LU

1986 81 400124075382001 West Whiteland 367CNSG IPT

1986 82 395927075405501 East Bradford 300WSCKA DU

1986 83 395346075421001 East Marlborough 300WSCKO LU

1986 84 400738075335501 East Pikeland 231SCKN IPT x

1986 85 395706075453001 West Bradford 300WSCKA DU

1986 86 400227075430801 East Brandywine 377CCKS DU

1986 88 400234075342601 East Whiteland 377LDGR IPT

1986 386 400800075323701 East Pikeland 231SCKN IPT

1986 410 395240075390801 Pennsbury 400FLCGH LU

1986 412 395957075503901 Valley 400BMFGA NA

1986 991 395810075534301 Sadsbury 377CCKS NA

1986 1000 395433075543601 Highland 300PRCK NA

1986 1074 395703075585001 Atglen Borough 377HRPR IPT h

1986 1299 395420075393701 Pocopson 3 300WSCKO LU

1986 1361 400109075545501 West Caln 377HRPR NA

1986 1364 400241075535201 West Caln 377CCKS NA m

1986 1370 400242075502901 West Caln 400BMFGA NA

1986 1435 400706075431501 East Nantmeal 400FLCGG NA

1986 1528 401259075405501 North Coventry 231HMCK NA

1986 1547 401200075354601 East Coventry 231BRCK NA

1986 1565 400935075360401 East Vincent 231LCKG NA

1986 1593 400800075343201 East Pikeland 231SCKN NA x m

1986 1613 400536075381501 West Pikeland 400GPCGA NA

1986 1627 400537075330701 Charlestown 400FCIGA NA

1986 1954 395002075460201 New Garden 300STRS NA

1986 1981 400126075341901 East Whiteland 300WSCKA NA

1986 1985 400238075320301 East Whiteland 367CNSG NA m

1986 2084 395947075304701 Willistown 400FLCGP NA

1986 2138 400350075291501 Tredyffrin 371ELBK NA

1986 2197 400512075291001 Schuylkill 377CCKS IPT m

1986 2271 400425075490801 West Brandywine 000ANRS NA

1986 2293 395549075341801 Westtown 400FLCGH NA

1986 2308 400049075324901 East Goshen 300WSCKO NA

1986 2403 395936075542501 West Caln 377CCKS DU, NA x m m

1986 2415 395731075485201 South Coatesville 300PRCK DU x

1986 2429 400227075431201 East Brandywine 377CCKS NA m

1986 2436 400313075365501 West Pikeland 377CCKS NA m

1986 2482 400731075340201 East Pikeland 400GPCGA IPT x

1986 2505 395707075441401 West Bradford 300PRCK IPT x m

1986 2541 400254075335801 East Whiteland 377CCKS IPT

1986 2555 400422075331601 East Whiteland 377CCKS IPT

1986 2605 400403075321601 East Whiteland 367CNSG IPT x m

1986 2714 400102075423601 Caln B-1 377LDGR IPT

1986 2745 400158075352801 West Whiteland 367CNSG IPT

1986 2746 400200075365001 West Whiteland 377LDGR NA

1986 2769 395131075503401 London Grove 300STRS NA

1986 3048 395820075530501 Sadsbury 400FMFG NA

1986 3073 395323075350001 Birmingham 000MFCGH NA

1986 3219 400243075534301 West Caln 377CCKS NA m
Appendix 1 61

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1987 206 400555075413901 Upper Uwchlan 400GPCGA IPT x

1987 249 400103075390101 West Whiteland 377LDGR LU, NA m

1987 889 395932075475901 Caln 377VNTG DU

1987 992 395808075530301 Sadsbury 377HRPR NA

1987 1097 400214075555101 West Caln 377ANTM NA

1987 1099 400927075492701 Elverson Borough 400FLCGG IPT x m

1987 1483 401020075433501 Warwick 231SCKN NA

1987 1496 401143075414801 South Coventry 231HMCK NA

1987 1499 401039075391101 South Coventry 231LCKG NA

1987 1501 401032075394701 South Coventry 231SCKN NA

1987 1564 400928075345501 East Vincent 231LCKG NA

1987 1567 400954075354501 East Vincent 231BRCK NA

1987 1727 395120075583101 Upper Oxford 300PRCK NA

1987 2062 395202075451401 East Marlborough 300STRS NA

1987 2199 400313075341301 East Whiteland 377LDGR IPT

1987 2424 395744075473901 East Fallowfield 300WSCKA IPT

1987 2430 395812075403401 West Bradford 300WSCKO IPT

1987 2448 400258075311001 East Whiteland 367CNSG IPT x

1987 2465 400930075321201 East Pikeland 231LCKG IPT

1987 2469 400815075342801 East Pikeland 231SCKN DU x

1987 2474 395744075480501 Modena Borough 300WSCKA IPT

1987 2543 400244075333701 East Whiteland 377LDGR IPT m

1987 2569 400402075312901 Tredyffrin 371ELBK DU x m

1987 2591 395011075444501 New Garden 300CCKV LU x

1987 2611 400344075311101 Tredyffrin 371ELBK DU

1987 2766 395100075503101 London Grove 300STRS NA

1987 2828 395750075530201 Sadsbury 367CNSG NA

1987 2998 400611075543801 Honey Brook 400FLCGG DU m

1987 2999 400308075331701 East Whiteland 377ANTM IPT

1987 3000 400811075342001 East Pikeland 231SCKN IPT

1987 3076 400221075530401 West Caln 377CCKS DU, NA h m

1987 3077 400601075501401 West Nantmeal 000ANRS IPT

1987 3078 400417075321701 East Whiteland 377LDGR IPT x m

1987 3079 400454075281701 Tredyffrin 377HRPR NA

1987 3080 400557075503501 West Nantmeal 000ANRS DU x

1987 3081 400014075491801 Valley 400FCIGA IPT

1987 3082 395709075441001 West Bradford 300PRCK IPT x

1987 3083 395659075441201 West Bradford 300PRCK IPT x m

1987 3084 394941075441901 New Garden 300WSCKO LU

1987 3085 395927075404901 East Bradford 300WSCKA DU h

1987 3092 400927075335801 East Vincent 231LCKG NA

1987 3099 401004075362501 East Vincent 231BRCK NA

1987 3100 400947075335001 East Vincent 231BRCK NA

1987 3103 401049075381601 East Vincent 231BRCK NA

1987 3105 401050075402401 South Coventry 231HMCK NA

1987 3106 400911075360401 East Vincent 231SCKN NA

1987 3107 401117075433001 Warwick 231SCKN NA

1987 3108 401253075395201 North Coventry 231HMCK NA

1987 3110 395123075421301 Kennett 400FLCGH DU
62 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1987 3115 401336075413601 North Coventry 231BRCK NA

1987 3116 401246075381001 East Coventry 231BRCK NA

1987 3118 395443075552701 Highland 300PRCK NA

1987 3119 395337075550501 West Fallowfield 300PRCK NA

1987 3120 395251075581501 West Fallowfield 300PRCK NA

1987 3121 401152075383401 East Coventry 231HMCK NA

1987 3129 395057075400701 Kennett 300STRS NA

1987 3130 394832075435501 New Garden 300WSCKO IPT m

1987 3133 400217075534301 West Caln 377CCKS DU x m

1987 3136 400318075352601 East Whiteland 377HRPR NA m

1987 3213 400238075535301 West Caln 377CCKS IPT, NA x m
Appendix 1 63

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1988 69 395019075431501 Kennett 300CCKV LU x h

1988 204 400404075290001 Tredyffrin 371ELBK DU

1988 989 395737075535701 Sadsbury 367CNSG NA

1988 2161 400118075383201 West Whiteland 377LDGR NA

1988 2348 400008075401001 East Caln 377LDGR NA

1988 2437 394740075434201 New Garden 300WSCKO LU

1988 2443 400654075282401 Schulkill 231SCKN IPT x

1988 2474 395744075480501 Modena Borough 300WSCKA IPT

1988 2506 395632075453901 Newlin 300PRCK DU

1988 2634 400330075303601 Tredyffrin 371ELBK NA

1988 2663 394624075444001 New Garden 300CCKV LU

1988 2676 400402075304701 Tredyffrin 371ELBK DU x m

1988 2677 400356075295201 Tredyffrin 371ELBK DU x m

1988 2740 400153075353502 West Whiteland 367CNSG NA

1988 2840 395713075555601 West Sadsbury 367CNSG NA

1988 3000 400811075342001 East Pikeland DU

1988 3085 395927075404901 East Bradford 300WSCKA IPT

1988 3113 400507075290701 Tredyffrin 377CCKS IPT x m

1988 3227 400938075365901 East Vincent 231SCKN LU

1988 3275 401008075371801 East Vincent 231LCKG LU

1988 3289 400358075311301 Tredyffrin 371ELBK IPT x m

1988 3291 400405075311001 Tredyffrin 371ELBK IPT x

1988 3293 394937075442401 East Marlborough 000MFCGH LU x m

1988 3295 400817075342001 East Pikeland 231SCKN DU x h

1988 3296 400908075371401 South Coventry 231SCKN LU

1988 3297 395821075283601 Willistown 400FLCGH IPT m

1988 3298 400411075405101 Upper Uwchlan 400GPCGA LU

1988 3299 400534075411701 Upper Uwchlan 400GPCGA IPT

1988 3300 400622075310502 Schuylkill 400FCIGA IPT

1988 3302 395623075454902 Newlin 300PRCK DU

1988 3303 395811075281901 Willistown 400FLCGH IPT m

1988 3304 400818075342801 East Pikeland 231SCKN DU

1988 3306 395159075391101 Kennett 400FLCGH LU

1988 3307 394833075440401 New Garden 300WSCKO LU

1988 3308 395137075404701 East Marlborough 400FLCGH LU x m

1988 3309 395745075474101 Coatesville Borough 300WSCKA IPT m

1988 3310 394947075420301 Kennett 300WSCKO LU x m

1988 3312 394944075422401 Kennett 300WSCKO LU m

1988 3313 395018075415301 Kennett 000MFCGH LU m

1988 3314 394918075451301 New Garden 300WSCKO LU

1988 3316 395154075550901 West Fallowfield 300WSCKO IPT

1988 3317 395142075554401 Upper Oxford 300PRCK IPT

1988 3318 395000075422801 Kennett 000MFCGH LU

1988 3319 395152075501801 Londonderry 300WSCKA DU

1988 3320 395152075501802 Londonderry 300WSCKA DU

1988 3321 395104075390401 East Marlborough 400FLCGH LU

1988 3322 395104075383801 East Marlborough 300WSCKO LU

1988 3323 394957075445501 New Garden 300WSCKO LU x

1988 3324 400713075301301 Schuylkill 231SCKN IPT
64 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1989 85 395706075453001 West Bradford 300WSCKA DU

1989 87 395705075452701 West Bradford 300WSCKA DU

1989 848 395359075451901 East Marlborough 300WSCKO LU x

1989 2015 395010075432001 Kennett 300CCKV LU x

1989 2197 400512075291001 Schuylkill 377CCKS IPT

1989 2315 400239075371501 West Whiteland 377CCKS LU

1989 2411 400329075315501 East Whiteland 377LDGR DU x

1989 2494 400334075313801 East Whiteland 377LDGR DU

1989 2586 395040075403701 Kennett 300CCKV DU x

1989 2677 400356075295201 Tredyffrin 371ELBK DU x

1989 2740 400153075353502 West Whiteland 367CNSG LU

1989 2743 400224075370501 West Whiteland 377LDGR LU

1989 3112 400508075291901 Schuylkill 377CCKS IPT

1989 3310 394947075420301 Kennett 300WSCKO LU m

1989 3335 400332075361801 Charlestown 377CCKS IPT

1989 3355 400519075291701 Schuylkill 377CCKS LU

1989 3356 395313075451701 East Marlborough 300WSCKO IPT x

1989 3357 400812075341701 East Pikeland 231SCKN LU

1989 3358 395902075512201 Valley 400FMFG IPT

1989 3359 400822075342101 East Pikeland 231SCKN IPT

1989 3360 400517075291601 Schuylkill 377CCKS IPT

1989 3361 395629075342701 Westtown 400MFCGH LU

1989 3362 400220075364701 West Whiteland 377LDGR LU

1989 3363 400156075362901 West Whiteland 377LDGR LU x m

1989 3364 395807075514401 Valley 367CNSG DU

1989 3365 400237075540601 West Caln 377CCKS LU x m

1989 3458 394952075415201 Kennett 000MFCGH LU x

1989 3467 395135075413101 East Marlborough 400FLCGH LU x m

1989 3468 394948075421301 Kennett 000MFCGH LU x

1989 3469 394942075441401 New Garden 300WSCKO LU x

1989 3470 394947075434201 New Garden 300WSCKO LU

1989 3471 395049075403401 Kennett 300STRS LU

1989 3472 394757075433301 New Garden 300WSCKO LU

1989 3473 395053075395801 Kennett 300STRS LU x

1989 3474 395008075444101 New Garden 300CCKV IPT x

1989 3475 400816075341801 East Pikeland 231SCKN LU x h

1989 3478 394927075430401 Kennett 300WSCKO LU

1989 3539 395005075422801 Kennett 300WSCKO IPT x

1989 3540 395650075352601 West Goshen 400FLCGP LU x m m

1989 3551 400228075354402 West Whiteland 377CCKS DU

1989 3621 395148075502402 London Grove 300WSCKO DU x

1989 3622 395200075502601 London Grove 300WSCKO DU

1989 3623 395148075502401 London Grove 300WSCKO DU x
Appendix 1 65

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1990 75 394735075580901 Oxford Borough 300WSCKO LU x

1990 895 395438075484101 West Marlborough 300CCKV NA

1990 2161 400118075383201 West Whiteland 377LDGR IPT

1990 2724 400033075400901 East Caln 377LDGR IPT x m m

1990 2746 400200075365001 West Whiteland 377LDGR IPT

1990 2752 395753075374201 East Bradford 400FLCGH IPT

1990 2777 395045075474201 London Grove 300CCKV NA

1990 3310 394947075420301 Kennett 300WSCKO LU

1990 3316 395154075550901 West Fallowfield 300WSCKO IPT h

1990 3335 400332075361801 Charlestown 377CCKS NA m

1990 3613 401250075405901 North Coventry 231HMCK NA

1990 3624 395200075502602 London Grove 300WSCKO DU h

1990 3625 395147075503401 London Grove 300WSCKO DU x

1990 3627 395154075505701 London Grove 300WSCKO DU x m h

1990 3640 401316075421001 North Coventry 231BRCK NA

1990 3655 401302075431501 North Coventry 231BRCK NA

1990 3657 401236075433101 North Coventry 231HMCK NA

1990 3673 401342075431801 North Coventry 231HMCK NA

1990 3758 401058075383501 South Coventry 231HMCK NA

1990 3837 401408075400101 North Coventry 231BRCK NA

1990 3838 401411075421301 North Coventry 231BRCK NA

1990 3932 395156075510201 Londonderry 300WSCKO IPT x m

1990 4004 395312075431301 East Marlborough 300WSCKO IPT

1990 4005 394832075435701 New Garden 300WSCKO LU

1990 4006 395340075552501 West Fallowfield 300PRCK IPT

1990 4007 395013075464301 New Garden 300STRS LU

1990 4008 395220075473301 West Marlborough 400FLCGP LU

1990 4009 395334075551901 West Fallowfield 300PRCK IPT m

1990 4010 400527075471001 Wallace 000ANRS NA

1990 4022 400454075511601 Honey Brook 000ANRS NA

1990 4023 395108075382901 Kennett 300WSCKO LU x h

1990 4024 395200075405601 East Marlborough 400FLCGH LU

1990 4025 400516075510301 Honey Brook 000ANRS NA

1990 4026 394617075444901 New Garden 300CCKV NA

1990 SP41 400501075290901 Tredyffrin 377CCKS IPT

1990 SP42 400157075364001 West Whiteland 377LDGR IPT x m
66 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1991 307 400124075374101 West Whiteland 367CNSG IPT

1991 509 395157075510601 Londonderry 300WSCKO IPT m h

1991 1651 394555076030101 West Nottingham 300PRCK NA

1991 1659 394411076001801 West Nottingham 000SRPN NA

1991 1703 394445075580201 East Nottingham 300WSCKO NA

1991 1709 394859075591701 Lower Oxford 300PRCK NA

1991 1737 394752075545901 Lower Oxford 300WSCKO NA m

1991 1761 394407075562501 Elk 000SRPN NA

1991 1765 394620075541201 New London 300WSCKO NA

1991 2451 395727075414901 West Bradford 300WSCKO IPT

1991 2723 400103075395801 East Caln 367CNSG IPT

1991 2725 400058075384801 East Caln 371ELBK DU

1991 2730 400108075382501 West Whiteland 377LDGR IPT x

1991 2742 400227075361301 West Whiteland 377LDGR LU m

1991 2755 395137075501001 W Marlborough 400FLCGH IPT x m

1991 3272 401107075355901 South Coventry 231BRCK IPT

1991 3310 394947075420301 Kennett 300WSCKO LU m

1991 3335 400332075361801 Charlestown 377CCKS NA

1991 3561 395058075383701 Kennett 300WSCKO LU

1991 3841 401406075392201 North Coventry 231BRCK LU

1991 3926 400233075355601 West Whiteland 377LDGR LU x m

1991 4026 394617075444901 New Garden 300CCKV LU

1991 4118 394638075563601 East Nottingham 300WSCK NA

1991 4119 394854076010701 Lower Oxford 300PRCK NA m

1991 4120 394338076023901 West Nottingham 000SRPN NA

1991 4121 394913075463101 New Garden 300WSCKO LU

1991 4122 394814075464301 New Garden 300WSCKO LU x h m

1991 4123 395559075395301 East Bradford 400FLCGP IPT

1991 4124 400503075385901 West Pikeland 000GRPC IPT x

1991 4125 395106075382801 Kennett 300WSCKO LU

1991 4126 394753075582701 Lower Oxford 300WSCKO LU x h

1991 4127 395319075552101 West Fallowfield 300PRCK IPT x

1991 4128 395333075551902 West Fallowfield 300PRCK IPT x m

1991 4129 400026075400901 East Caln 367CNSG IPT x

1991 SP43 395200075501801 London Grove 300STRS IPT x
Appendix 1 67

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1992 1315 400205075372301 West Whiteland 377LDGR IPT x

1992 1316 400205075372101 West Whiteland 377LDGR IPT

1992 1617 400338075352701 Charlestown 377CCKS NA

1992 1720 394803075563801 Lower Oxford 300WSCKO LU x m

1992 2279 395916075381901 West Goshen 300PRCK LU

1992 2969 395949075390801 East Bradford 300WSCKA LU

1992 3335 400332075361801 Charlestown 377CCKS NA

1992 4148 395909075384701 East Bradford 300PRCK LU

1992 4270 395332075552101 West Fallowfield 300PRCK IPT h

1992 4271 395423075431101 Newlin 000SRPN; 

231DIBS

DU x

1992 4272 394523076044301 West Nottingham 300PRCK NA

1992 4273 394438076035601 West Nottingham 300PRCK NA

1992 4274 394439076035601 West Nottingham 300PRCK NA

1992 4275 394656075551801 East Nottingham 300WSCKO DU

1992 4276 401220075393701 North Coventry 231BRCK IPT x

1992 4277 401254075394901 North Coventry 231HMCK IPT

1992 4278 401244075390601 North Coventry 231HMCK IPT

1992 4291 395137075492801 London Grove 000PGMT NA

1992 4292 400106075381501 West Whiteland 367CNSG; 

371ELBK

IPT

1992 4293 400113075382701 West Whiteland 377LDGR IPT x

1992 4294 394857075504201 London Grove 300WSCKO LU

1992 4295 394913075502301 London Grove 300WSCKO LU x m

1992 4296 394647075484901 Franklin 300WSCKO LU x

1992 4297 394752075582201 Lower Oxford 300WSCKO LU x m

1992 4298 400458075382701 West Pikeland 400GPCGA IPT x

1992 4299 394659075450401 New Garden 000MFCGH;

300WSCKO

IPT x

1992 4341 394726075505501 New London 300WSCKO LU x m

1992 4342 395038075513601 Penn 300WSCKO LU x

1992 4343 395330075434401 East Marlborough 300WSCKO NA

1993 4344 395231075420101 East Marlborough 300CCKV NA

1992 SP44 395014075530201 Penn 300WSCKO NA
68 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1993 71 395017075433801 New Garden 300CCKV DU m

1993 1599 400501075385601 West Pikeland 400GPCGA IPT

1993 1720 394803075563801 Lower Oxford 300WSCKO LU x

1993 1978 400231075334701 East Whiteland 371ELBK IPT x

1993 1985 400238075320301 East Whiteland 367CNSG IPT x m

1993 2186 394755075583901 Lower Oxford 300WSCKO LU x

1993 2189 394646075592501 Oxford Borough 300WSCKO IPT

1993 2719 400020075401101 East Caln 300WSCKA IPT

1993 2728 400053075391801 West Whiteland 377LDGR IPT x

1993 3150 400656075324001 Charlestown 231SCKN IPT x

1993 3859 400214075334301 East Whiteland 367CNSG IPT x m

1993 4344 395231075420101 East Marlborough 300CCKV NA

1993 4409 401001075395701 South Coventry 231SCKN IPT x

1993 4411 395655075440001 West Bradford 300PRCK IPT h

1993 4491 401338075360201 East Coventry 231BRCK DU

1993 4493 401353075361801 East Coventry 231BRCK DU

1993 4495 394516076004601 East Nottingham 300WSCKA LU

1993 4496 401033075353401 East Vincent 231BRCK IPT

1993 4497 400749075323801 Schuylkill 231SCKN IPT x

1993 4498 400713075280301 Schuylkill 231SCKN IPT x

1993 4499 400104075383501 West Whiteland 377LDGR IPT x

1993 4500 394648076001701 East Nottingham 300WSCKA IPT m

1993 4501 394756075581601 Lower Oxford 300WSCKA LU

1993 4502 401243075351401 East Coventry 231BRCK DU x

1993 4546 395702075571201 West Sadsbury 367CNSG IPT

1993 4547 395940075541201 West Caln 000GRGS DU x

1993 4548 394922075500301 West Grove Borough 300CCKV IPT x

1993 4549 394802075461501 New Garden 000MFCGH LU x m

1993 4550 400652075281901 Schuylkill 231SCKN IPT x

1993 4551 394925075463201 Avondale Borough 300CCKV DU x

1993 4552 395024075431701 Kennett 300CCKV IPT x

1993 4553 395614075435701 Newlin 300PRCK DU
Appendix 1 69

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1994 2317 401006075431401 Warwick 400FLCGG LU

1994 2402 400313075315001 East Whiteland 377LDGR DU x

1994 2543 400244075333701 East Whiteland 377LDGR IPT

1994 2611 400344075311101 Tredyffrin 371ELBK DU

1994 3384 395201075421601 East Marlborough 400FLCGH LU x

1994 3430 395123075400201 Kennett 400FLCGH LU x

1994 3445 394833075440101 New Garden 300WSCKO LU

1994 3482 395115075441101 East Marlborough 400FLCGH LU x

1994 3484 395054075450601 New Garden 400FLCGH LU x

1994 3516 395131075454401 West Marlborough 300CCKV LU x m

1994 4344 395231075420101 East Marlborough 300CCKV LU x

1994 4345 394842075423801 Kennett 300WSCKO LU x

1994 4730 395048075413601 Kennett 300STRS LU x h m

1994 4801 401228075353201 East Coventry 231BRCK DU x

1994 4802 400055075421801 Caln 377KZRS IPT x

1994 4803 401017075352901 East Vincent 231BRCK DU x

1994 4804 400327075314801 East Whiteland 377LDGR DU x

1994 4805 400241075332101 East Whiteland 371ELBK IPT

1994 4806 394750075582901 Lower Oxford 300WSCKO LU x m

1994 4807 394812075442901 New Garden 300WSCKO IPT

1994 4808 394758075450401 New Garden 000MFCGH IPT x m m

1994 4809 395044075435601 New Garden 300STRS LU

1994 5087 400202075504001 West Caln 400BMFGA LU

1994 5088 400152075512701 West Caln 400BMFGA LU x

1994 5089 400151075512601 West Caln 400BMFGA LU x

1994 5090 395712075440901 West Bradford 300PRCK IPT x

1994 5091 400106075552301 West Caln 377AMHP DU

1994 SP48 400212075335001 East Whiteland 367CNSG IPT x

1994 SP49 400248075320001 East Whiteland 367CNSG IPT x m
70 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1995 30 395046075415001 Kennett 300STRS LU x m

1995 2461 394940075525901 Penn 300WSCKO LU x m m

1995 2497 400136075385501 West Whiteland 377LDGR LU x

1995 2676 400402075304701 Tredyffrin 371ELBK DU x

1995 3859 400214075334301 East Whiteland 367CNSG IPT x m

1995 4133 394858075482301 London Grove 300WSCKO LU x m

1995 4339 400238075465901 East Brandywine 400FCIGA LU x

1995 4539 400229075465601 East Brandywine 400FCIGA LU x

1995 4767 400123075544401 West Caln 377AMHP DU

1995 4768 400918075303201 Schuylkill 231LCKG DU

1995 4769 401107075343201 East Vincent 231BRCK LU x

1995 4770 400409075384301 Uwchlan 400GPCGA LU x

1995 4771 400122075543201 West Caln 377CCKS DU x

1995 4772 400045075381301 West Whiteland 300WSCKA DU

1995 4778 400016075473201 Caln 400FCIGA IPT x

1995 4779 395902075513801 Valley 400FMFG DU

1995 5220 395709075441601 West Bradford 300PRCK IPT x m

1995 5221 395105075412101 Kennett 400FLCGH LU m m

1995 5222 395017075442701 New Garden 300CCKV LU x m

1995 5223 394918075450801 New Garden 300WSCKO NA x m

1995 5225 394427076022101 Nottingham 000SRPN LU

1995 5226 394347076031101 Nottingham 000SRPN LU

1995 5227 395924075405601 East Bradford 300WSCKA DU x m

1995 5228 395345075413201 Pocopson 300WSCKO LU

1995 5229 394942075420001 Kennett 300WSCKO LU m

1995 5238 400227075463701 East Brandywine 400FCIGA LU x

1995 5259 395610075334301 Westtown 400FLCGH LU x

1995 5260 395612075334701 Westtown 400FLCGH LU

1995 5261 395614075335701 Westtown 400FLCGH LU

1995 5269 400911075364601 East Vincent 231SCKN LU x

1995 5270 400922075364701 East Vincent 231SCKN LU x

1995 5272 400918075365801 East Vincent 231SCKN LU x
Appendix 1 71

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1996 202 400404075284501 Tredyffrin 371ELBK IPT

1996 204 400404075290001 Tredyffrin 371ELBK DU x m

1996 245 400300075290001 Tredyffrin 371ELBK DU

1996 1110 400114075322301 Willistown 300WSCKO LU

1996 2033 395228075421901 E Marlborough 300CCKV LU x

1996 2560 400427075320601 Charlestown 371ELBK IPT

1996 2574 400423075310101 Tredyffrin 377LDGR IPT h

1996 3184 400935075331801 East Pikeland 231BRCK LU x

1996 4261 400111075491801 W Brandywine 400FCIGA LU

1996 4815 400447075431201 Upper Uwchlan 400GPCGA LU x

1996 5469 400047075312701 Willistown 000SRPN NA

1996 5470 394847075582401 Lower Oxford 300PRCK LU x

1996 5471 394958075480201 London Grove 300CCKV LU

1996 5472 395914075534901 Sadsbury 400FMFG LU

1996 5473 400213075512901 West Caln 400BMFGA LU x

1996 5474 394942075495801 London Grove 300WSCKO LU x

1996 5475 395722075454601 West Bradford 300WSCKA DU x

1996 5476 394732075561001 East Nottingham 300WSCKO LU

1996 5477 394620075561201 East Nottingham 300WSCKO DU

1996 5478 395009075470801 London Grove 300CCKV LU x

1996 5479 394913075522901 Penn 300WSCKO LU

1996 5480 395343075435301 East Marlborough 300WSCKO LU x

1996 5481 400620075433501 Upper Uwchlan 400FLCGG LU

Temporal radon

1996 1514 395912075394001 East Bradford 300PRCK NA

1996 3484 395054075450601 New Garden 400FLCGH NA

1996 4027 400448075371001 West Pikeland 400GPCGA NA

1996 4339 400238075465901 East Brandywine 400FCIGA NA

1996 5238 400227075463701 East Brandywine 400FCIGA NA
72 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1997 432 395202075402001 East Marlborough 400FLCGH LU x

1997 1281 400538075533001 Honey Brook 400FLCGG LU

1997 4573 400152075474801 West Brandywine 400FLCGA LU x m

1997 5553 395704075483801 East Fallowfield 300PRCK LU

1997 5554 400639075555801 Honey Brook 400FLCGG DU m

1997 5555 394942075461201 New Garden 300CCKV LU x

1997 5556 400944075371301 East Vincent 231SCKN LU

1997 5557 400338075483601 West Brandywine 377CCKS LU x

1997 5558 395924075425001 West Bradford 300WSCKA LU m

1997 5559 395314075422301 East Marlborough 300WSCKO IPT x

1997 5560 394332076040101 West Nottingham 000SRPN LU x m

1997 5561 394920075463301 New Garden 300CCKV LU m

1997 5562 394906075461201 New Garden 300WSCKO IPT x

1997 5563 395917075424201 West Bradford 300WSCKA LU x

Temporal radon

1997 1514 395912075394001 East Bradford 300PRCK NA

1997 3484 395054075450601 New Garden 400FLCGH NA

1997 4027 400448075371001 West Pikeland 400GPCGA NA

1997 4339 400238075465901 East Brandywine 400FCIGA NA

1997 5238 400227075463701 East Brandywine 400FCIGA NA
Appendix 1 73

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1998 2311 395331075544101 Highland 300PRCK LU x m

1998 4817 400543075435501 Upper Uwchlan 400FLCGG LU

1998 4828 400203075384201 West Whiteland 377CCKS LU

1998 5160 395807075425301 West Bradford 300WSCKA LU x

1998 5243 400215075405001 Uwchlan 377CCKS DU x

1998 5244 400216075405101 Uwchlan 377CCKS DU x

1998 5559 395314075422301 East Marlborough 300WSCKO IPT
74 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

1999 992 395808075530301 Sadsbury 377HRPR NA m m, h m

1999 1616 400329075362201 Charlestown 377CCKS NA m

1999 1985 400238075320301 East Whiteland 367CNSG NA m

1999 2161 400118075383201 West Whiteland 377LDGR NA

1999 2766 395100075503101 London Grove 300STRS NA

1999 2769 395131075503401 London Grove 300STRS DU, NA

1999 3115 401336075413601 North Coventry 231BRCK NA

1999 3117 400148075430101 East Brandywine 400FCIGA NA m

1999 3119 395337075550501 West Fallowfield 300PRCK NA

1999 3136 400318075352601 East Whiteland 377HRPR NA

1999 3330 400010075565001 West Sadsbury 377CCKS NA

1999 3331 400507075292401 Schuylkill 377CCKS NA m m

1999 3334 400510075292501 Schuylkill 377CCKS NA m m

1999 5364 405732075541001 Sadsbury 367CNSG DU x
Appendix 1 75

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

2000 75 394735075580901 Oxford Borough 300WSCKO LU

2000 543 394601076030001 West Nottingham 300WSCKO LU

2000 1037 395542075561401 Highland 300PRCK LU x m

2000 1281 400538075533001 Honeybrook 400FLCGG LU m

2000 1652 394508076045001 West Nottingham 300PRCK LU x m

2000 1664 394513076014201 West Nottingham 300WSCKO LU x

2000 1667 394430076015501 West Nottingham 300WSCKO LU

2000 1680 394535076003001 East Nottingham 300WSCKO LU x m

2000 1705 394640076021801 Lower Oxford 300WSCKO LU x

2000 1710 394900075591701 Lower Oxford 300PRCK LU x

2000 1735 394628075592601 East Nottingham 300WSCKO LU x

2000 1743 395021075591701 Upper Oxford 300PRCK LU x

2000 1757 395328075573301 West Fallowfield 300PRCK LU x m

2000 3331 400507075292401 Schuylkill 377CCKS LU

2000 3516 395131075454401 West Marlborough 300CCKV LU m

2000 4413 395130075454501 West Marlborough 300CCKV LU

2000 4420 395939075575701 West Sadsbury 400BMFGA LU x

2000 4730 395048075413601 Kennett 300STRS LU x m

2000 5230 395207075575502 West Fallowfield 300PRCK LU x m

2000 5266 394814075591401 Lower Oxford 300PRCK LU x

2000 5365 395833075581201 West Sadsbury 000PGMT LU x

2000 5377 395058075574901 Upper Oxford 300PRCK LU x

2000 5450 394527075515601 New London 000PGMT IPT x

2000 5593 394755076020601 Lower Oxford 300PRCK LU x

2000 5920 395439075553601 Highland 300PRCK LU x m

2000 5921 395638075562901 Highland 300WSCKA LU x

2000 5922 395310075555301 West Fallowfield 300PRCK LU x

2000 5937 394818076002401 Lower Oxford 300PRCK LU x

2000 5938 400121075295401 Willistown 000SRPN IPT x

2000 -- 01578343 Valley Creek LU x

2000 -- 01578349 Leech Run LU x

2000 -- 01578352 Muddy Run LU x

2000 -- 0157834749 Knight Run LU x

2000 -- 01578457 Tweed Creek LU x

2000 -- 01578466 Blackburn Run LU x

2000 -- 01578469 Black Run LU x
76 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

2001 1283 400724075514701 Honey Brook 400FLCGG LU x m

2001 1435 400706075431501 East Nantmeal 400FLCGG LU

2001 1730 394418075591201 East Nottingham 300WSCKO LU x

2001 4884 401127075433101 Warwick 231SCKN LU

2001 5680 400850075421901 East Nantmeal 400GPCGG LU

2001 5703 401107075435801 Warwick 112ALVM LU

2001 5995 400633075501302 West Nantmeal 000ANRS LU

2001 5996 400537075490901 West Nantmeal 000ANRS LU

2001 5997 394319076013101 East Nottingham 000SRPN LU

2001 5998 400833075470401 East Nantmeal 000QZMZ LU x m

2001 6399 395901075271801 Willistown 400FLCGH LU x

2001 6400 400107075293902 Willistown 000MFCGP LU x

2001 6401 394322075481001 London Britain 300WSCKO LU

2001 6402 394417075484501 London Britain 300WSCKO LU x

2001 6403 394520075592001 East Nottingham 300WSCKO LU x

2001 6404 394400075584901 East Nottingham 000SRPN LU h

2001 6405 395251075373101 Pennsbury 400FLCGH LU

2001 6406 395339075374501 Pennsbury 300WSCKO LU

2001 6407 395148075532301 Londonderry 300WSCKO LU

2001 6408 395145075513601 Londonderry 300WSCKO LU x

2001 6496 401104075434301 Warwick 231DIBS LU
Appendix 1 77

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

2002 410 395240075390801 Pennsbury 400FLCGH LU x

2002 5178 395049075434301 New Garden MW-7 400FLCGA LU

2002 6653 395239075434701 East Marlborough MW 4 400FLCGH LU

2002 6654 395454075350901 Westtown MW 1 300WSCKO LU x

2002 6655 395238075391601 Kennett MW4 400FLCGH LU x

2002 6656 400024075334601 East Goshen MW 7 300WSCKO LU x
78 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

2003 86 400227075430801 East Brandywine 377CCKS NA m

2003 992 395808075530301 Sadsbury 377HRPR NA m h

2003 1616 400329075362201 Charlestown 377CCKS NA m

2003 2570 400424075313601 Tredyffrin 377CCKS NA

2003 3125 400224075432701 East Brandywine 377CCKS NA m

2003 3327 400212075541101 West Caln 377CCKS NA m

2003 3995 400543075281001 Schuylkill 377CCKS NA

2003 4771 400122075543201 West Caln 377CCKS NA m

2003 6514 400126075551001 West Caln 377AMHP NA

2003 6515 400037075550101 West Caln 377CCKS NA m

2003 6517 400247075532401 West Caln 377CCKS NA

2003 6535 400008075535901 West Caln 377CCKS NA

2003 6643 400652075554001 Honey Brook 377CCKS NA

2003 6644 400505075292401 Tredyffrin 377CCKS NA m

2003 6646 395957075543601 West Caln 377CCKS NA m

2003 6647 395951075543001 West Caln 377CCKS NA

2003 6824 400247075545901 West Caln 377CCKS NA m
Appendix 1 79

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

2004 No data collected—Review of lead data
80 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

2005 755 395651075405601 West Bradford 300WSCKO LU x m

2005 6673 395735075425301 West Bradford 300PRCK LU

2005 6878 395654075405001 West Bradford 300WSCKO LU x

2005 6879 395752075424801 West Bradford 300PRCK LU

2005 6880 395815075435501 West Bradford 300WSCKA LU

2005 6881 395701075404401 West Bradford 300WSCKO LU x

2005 6882 395807075432201 West Bradford 300WSCKA LU

2005 6883 395715075404401 West Bradford 300WSCKO LU

2005 SP70 395807075450201 West Bradford 300WSCKA LU x

2005 SP71 395642075403801 West Bradford 231DIBS LU x

2005 -- 0148063522 Unnamed tributary to 

Broad Run

LU

2005 -- 0148063532 Unnamed tributary to 

Broad Run

LU x

2005 -- 014806366 Little Broad Run at 

Shadyside

LU x

2005 -- 014806368 Unnamed tributary to 

Little Broad Run

LU x

2005 -- 014806369 Little Broad Run at 

Shadyside

LU x

2005 -- 01480637 Little Broad Run at 

Shadyside

LU x

2005 -- 014806374 Outfall to Broad Run LU

2005 -- 014806384 Unnamed tributary to 

Broad Run

LU x

2005 -- 014806394 Unnamed tributary to 

unnamed tributary to 

W Br Brandywine

LU x

2005 -- 01480913 Unnamed tributary to E 

Br Brandywine

LU x
Appendix 1 81

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

2006 83 395346075421001 East Marlborough 300WSCKO NA

2006 1483 401020075433501 Warwick 231SCKN NA

2006 1613 400536075381501 West Pikeland 400GPCGA NA

2006 1801 394417075471501 London Britain 000MFCGH NA

2006 1978 400231075334701 East Whiteland 371ELBK NA

2006 1985 400238075320301 East Whiteland 367CNSG NA m

2006 2021 394933075403801 Kennett 300WSCKO NA

2006 2189 394646075592501 Oxford Borough 300WSCKO NA

2006 2421 395322075561701 West Fallowfield 300PRCK NA

2006 2433 400620075563801 Honey Brook 377CCKS NA m

2006 2725 400058075384801 East Caln 371ELBK NA

2006 2766 395100075503101 London Grove 300STRS NA

2006 3077 400601075501401 West Nantmeal 000ANRS NA

2006 3117 400148075430101 East Brandywine 400FCIGA NA

2006 3300 400622075310502 Schuylkill 400FCIGA NA

2006 3302 395623075454902 Newlin 300PRCK NA

2006 3334 400510075292501 Schuylkill 377CCKS NA m

2006 3365 400237075540601 West Caln 377CCKS NA m m

2006 3918 395947075391301 East Bradford 300WSCKA NA

2006 4155 400207075441301 East Brandywine 400FCIGA NA

2006 4195 400258075412801 Uwchlan 400FCIGA NA

2006 4294 394857075504201 London Grove 300WSCKO NA

2006 4505 400211075475901 West Brandywine 400FLCGA DU m

2006 4817 400543075435501 Upper Uwchlan 400FLCGG NA

2006 5221 395105075412101 Kennett 400FLCGH NA m

2006 5457 395142075533501 Londonderry 300WSCKO NA

2006 6538 395311075552401 West Fallowfield 300PRCK NA m

2006 7266 400353075283401 Tredyffrin 371ELBK NA

2006 7267 400712075332601 East Pikeland 231SCKN NA

2006 7268 400026075380601 West Whiteland 300WSCKA NA
82 Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

2007 7220 400151075463101 East Brandywine 400FCIGA LU

2007 7236 400147075462501 East Brandywine 400BMFGA LU x

2007 -- 01472080 Pigeon Creek LU x

2007 -- 01472110 Stony Run LU x

2007 -- 014806215 Buck Run LU x

2007 -- 0148063528 Broad Run LU x

2007 -- 01480656 Indian Run LU x

2007 -- 01480662 Culbertson Run LU x

2007 -- 01480739 Beaver Creek LU x m

2007 -- 01480742 Beaver Creek tributary LU x

2007 -- 01480743 Beaver Creek LU x

2007 -- 014807434 Beaver Creek tributary LU x m

2007 -- 014807438 Beaver Creek tributary LU

2007 -- 01480744 Beaver Creek reservoir LU x

2007 -- 014807447 Beaver Creek reservoir 

outfall

LU x

2007 -- 01480745 Beaver Creek LU x

2007 -- 01480750 Beaver Creek LU x
Appendix 1 83

Appendix 1. List of wells and streams sampled by year and summary of water-quality-sampling results for the Chester County 

groundwater-quality monitoring program, 1980–2008.—Continued

Year 

sampled

Local 

well 

number

Station number Township/Stream Gunit Reason 

sampled

Manmade 

organic 

compound

VOC

MCL or HA exceeded

PesticideNutrient Metal Radchem

2008 4230 400045075490201 LU

2008 4261 400111075491801 LU x

2008 5435 400643075422501 LU x

2008 5445 400114075321201 LU x

2008 5444 400556075420301 LU x

2008 -- 01480160 Unnamed trib to W Br. 

Brandywine Creek

LU x

2008 -- 01480457 Rock Run LU x

2008 -- 01476420 Unnamed trib to Ridley 

Creek

LU x

2008 -- 01478147 Unnamed trib E Br 

White Clay Creek

LU x

2008 -- 014806775 Black Horse Creek LU x

Prepared by the West Trenton Publishing Service 

Center.

For more information concerning this report, contact:

Director

U.S. Geological Survey

Pennsylvania Water Science Center

215 Limekiln Road

New Cumberland, PA 17070

dc_pa@usgs.gov

or visit our Web site at:

http://pa.water.usgs.gov
Senior and Sloto—Groundwater-Quality Monitoring Program in Chester County, Pennsylvania, 1980–2008—Scientific Investigations Report 2010–5087