In cooperation with the Pennsylvania Department of Health and the 

Pennsylvania Department of Environmental Protection 

Reconnaissance of Arsenic Concentrations in 

Ground Water From Bedrock and 

Unconsolidated Aquifers in Eight NorthernTier Counties of Pennsylvania

U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2006–1376

Reconnaissance of Arsenic Concentrations 

in Ground Water From Bedrock and 

Unconsolidated Aquifers in Eight NorthernTier Counties of Pennsylvania

By Dennis J. Low and Daniel G. Galeone 

U.S. Department of the Interior

U.S. Geological Survey

In cooperation with the Pennsylvania Department of Health and the 

Pennsylvania Department of Environmental Protection 

Open-File Report 2006-1376
U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

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

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Suggested citation:

Low, D.J., and Galeone, D.G., 2007, Reconnaissance of arsenic concentrations in ground water from bedrock and unconsolidated aquifers in eight northern-tier counties of Pennsylvania: U.S. Geological Survey Open-File Report 2006-1376, 

35 p. 
 iii

Contents

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

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

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

Previous Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Description of Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Geohydrology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Bedrock Aquifers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Unconsolidated Aquifers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Water Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Methods of Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Sampling Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Well and Spring Owner Participation and Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Targeted Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Laboratory Procedures and Quality Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Arsenic Concentrations in Ground Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Reconnaissance of Total-Arsenic Concentrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Relation of Total Arsenic To Geology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Relation of Total Arsenic to Iron Staining and Hydrogen Sulfide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Redox Conditions and Concentrations of Arsenic Species. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

References Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Appendix 1 - U.S. Geological Survey Homeowner Questionnaire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Appendix 2 - Records of selected wells and springs, northern-tier counties, Pennsylvania . . . . . . . . . . . . . . . . . . 25

Figures

1-5. Maps showing:

1. Location of the eight counties that comprise the study area, northern-tier counties 

of Pennsylvania. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

2. The generalized bedrock geology of the study area, northern-tier counties of Pennsylvania . . . .5

3. The extent of the Wisconsin ice sheet and major valley fill deposits in the study area, 

northern-tier counties of Pennsylvania. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

4. The location of sampled sites and ranges of total-arsenic concentrations, northern-tier 

counties of Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

5. The location of sampled sites and ranges of total-arsenic concentrations in Tioga 

County. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

6. Graph showing distribution of total-arsenic concentration and well depth by geologic units, 

northern-tier counties of Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
iv 

Tables

1. Generalized geologic column and dominant rock type(s), northern-tier counties of Pennsylvania . . .7

2. Results of quality control for analyses of total-arsenic concentration, Pennsylvania 

Department of Environmental Protection Laboratory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3. Results of quality control for analyses of dissolved arsenic and arsenic species, 

U.S. Geological Survey National Water Quality Laboratory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

4. Number of well and spring samples collected for total-arsenic analysis and water use, 

northern-tier counties of Pennsylvania. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

5. Well depths and well-owner observations on the presence (or absence) of iron staining 

and (or) hydrogen-sulfide odor for wells containing water with total-arsenic concentrations 

of 4 μg /L or greater, northern-tier counties of Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

6. Dissolved arsenic and arsenic species concentrations and field-water-quality measurements 

for wells that contain water with dissolved arsenic concentrations greater than 10 μg /L, 

northern-tier counties of Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Conversion Factors, Datums, and Abbreviations

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 National Geodetic Vertical Datum of 1929 

(NGVD 29).

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

and the North American Datum of 1927 (NAD 27).

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).

Other abbreviations:

mL, milliliter

μL, microliter

mv, millivolts 

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2) 2.590 square kilometer (km2) 

Volume

gallon (gal) 3.785 liter (L) 

Flow rate

gallon per minute (gal/min) 0.06309 liter per second (L/s)
Reconnaissance of Arsenic Concentrations in Ground 

Water From Bedrock and Unconsolidated Aquifers in 

Eight Northern-Tier Counties of Pennsylvania

By Dennis J. Low and Daniel G. Galeone

Abstract 

Samples of ground water for analysis of total-arsenic concentrations were collected in eight counties–Potter, Tioga, 

Bradford, Susquehanna, Wayne, Pike, Sullivan, and Wyoming–

and from eight bedrock formations (bedrock aquifers) and overlying glacial aquifers in the north-central and northeastern parts 

of Pennsylvania in July 2005 and from March through June 

2006. The samples were collected from a total of 143 domestic 

wells, 2 stock wells, 4 non-community wells, 2 community 

water-system wells, and 3 domestic springs by well or spring 

owners using sampling kits provided by the U.S. Geological 

Survey (USGS). An additional 15 domestic wells were sampled 

by the USGS for analysis of total arsenic. These 15 samples 

were collected using the same methods and sampling kits provided to the homeowners.

Samples were analyzed for total arsenic by the Pennsylvania Department of Environmental Protection Laboratory using 

a minimum reporting level of 4.0 μg/L (micrograms per liter). 

Arsenic was detected in water from 18 domestic wells in four 

counties–Bradford (3 wells), Sullivan (1 well), Tioga (13 

wells), and Wayne (1 well). The median concentration of total 

arsenic was less than 4.0 μg/L, and the maximum concentration 

was 188 μg/L. Water from 10 wells had concentrations of total 

arsenic greater than the U.S. Environmental Protection Agency 

Maximum Contaminant Level of 10 μg/L. 

Detectable concentrations of total arsenic were measured 

in water from wells that ranged in depth from 29 to 400 feet, and 

that were completed in three aquifers–Lock Haven Formation, 

Catskill Formation, and unconsolidated glacial sediments; no 

springs had detectable concentrations of total arsenic. Water 

samples representing the Lock Haven Formation were collected 

from 60 wells; water from 12 of these wells had detectable concentrations of total arsenic. Water samples representing the 

Catskill Formation were collected from 57 wells; water from 4 

wells had detectable concentrations of total arsenic. Water samples representing the unconsolidated glacial sediments were 

collected from 17 wells; 2 wells had water with detectable concentrations of total arsenic. 

Contingency tables tested for significant differences in 

total arsenic between aquifers, topographic settings, and well 

depths. Concentrations of total arsenic were significantly 

greater (95-percent confidence level) in the Lock Haven Formation than in the other bedrock units. Concentrations of total 

arsenic also varied significantly by topographic setting. Wells 

completed in the Lock Haven Formation and located in valleys 

had significantly greater concentrations of total arsenic than 

similar wells located on hilltops or slopes. Concentrations of 

total arsenic did not vary significantly by topographic setting in 

the Catskill Formation. Concentrations of total arsenic did not 

vary significantly by well depth for any aquifer.

Iron staining, hydrogen-sulfide odor, or both were common complaints of well owners. Iron staining was a complaint 

of 44 well owners. Hydrogen-sulfide odor was a complaint of 

35 well owners. Fourteen well owners complained of both iron 

staining and hydrogen sulfide. No correlation to the presence of 

arsenic in the wells sampled was found with iron staining, 

hydrogen-sulfide odor, or both.

Water from 8 of the 10 wells that contained concentrations 

of total arsenic greater than 10 μg/L were sampled by USGS 

personnel for the determination of concentrations of dissolved 

arsenic (minimum reporting level 0.3 μg/L) and arsenic species 

{arsenite [As (III)], arsenate [As (V)], monomethylarsonate 

(MMA), and dimethylarsinate (DMA)} at the USGS National 

Water Quality Laboratory. Analytical results from these samples showed a median concentration of 38.7 μg/L dissolved 

arsenic in water and a maximum of 178 μg/L. As (III) was the 

most common arsenic species present in the water for seven of 

the eight wells and was found in water characteristic of reducing 

environments [pH 8.2 to 9.1, dissolved oxygen 0.06 to 0.29 milligrams per liter (mg/L), and oxidation reduction potential -63 

to -203 millivolts (mv)]. As (V) was the dominant arsenic species in water characteristic of an oxidizing environment (pH 

4.8, dissolved oxygen 2.15 mg/L, oxidation reduction potential 

265 mv). The arsenic species MMA and DMA were detected in 

the water from two wells. The arsenic species MMA was 

detected at an estimated concentration of 0.9 μg/L in water from 

one well; the concentration was less than 1.2 μg/L in water from 

seven wells. The arsenic species DMA was detected at concentrations of 1.0 and 1.5 μg/L in water from two wells; the concentration was less than 0.6 μg/L in water from six wells. Both 

wells that contained detectable concentrations of MMA and 
2 Reconnaissance of Arsenic Concentrations in Ground Water in Eight Northern-Tier Counties of Pennsylvania 

DMA produced water that was characteristic of reducing environments.

Introduction

Almost 1 million households (19.8 percent) or 2.2 million 

people in Pennsylvania obtain their drinking water from privately owned drilled or dug wells (U.S. Census Bureau, 1990; 

Hutson and others, 2000). This water is not regularly tested for 

contaminants.

Long-term ingestion of arsenic in drinking water can 

increase the risk of skin, lung, bladder, kidney, liver, and prostate cancer, as well as several non-cancerous ailments including 

cardiovascular disease, diabetes, and neurological dysfunction 

(National Research Council, 1999, 2001; Twarakavi and Kaluarachchi, 2006). In recognition of the health risks associated 

with arsenic, the U.S. Environmental Protection Agency 

(USEPA) decreased the Maximum Contaminant Level (MCL) 

from 50 to 10 μg/L (U.S. Environmental Protection Agency, 

2001). 

In the northern-tier counties–Potter, Tioga, Bradford, Susquehanna, Wayne, Pike, Sullivan, and Wyoming–of Pennsylvania, elevated concentrations of arsenic (> 10 μg/L) have been 

reported in public and private water-supply wells that obtain 

water from glacial and bedrock aquifers (Taylor and others, 

1983; Taylor, 1984; Taylor and Werkheiser, 1984; Williams 

and others, 1998). The distribution of arsenic in sampled wells 

appears random and unpredictable even over relatively short 

distances (less than 1 mi). This is also the case in southwestern 

Ohio (Thomas and others, 2005), Michigan (Kolker and others, 

2003), New Hampshire (Ayotte and others, 1999, 2003), and 

many parts of the world (Smedley, 2003). It is not clear which 

combination(s) of hydrologic, geologic, and geochemical factors and (or) well-construction characteristics are responsible 

for elevated concentrations of arsenic in ground water.

Arsenic occurs naturally in the bedrock and unconsolidated aquifers in many areas of the United States. According to 

Welch and others (1988), arsenic concentrations are particularly elevated in marine shales. Ryker (2003) notes arsenic concentrations can vary over time and can be influenced by local 

pumping effects. Hem (1985) stresses the importance of the 

mineralogy of the aquifer and the geochemistry of the ground 

water passing through the aquifer. Although the parent source 

of arsenic in aquifers is rarely determined, arsenean pyrite 

[Fe(S,As)2], arsenopyrite (FeAsS), and (or) other unspecified 

sulfide minerals are often proposed (Foster, 2003). Hydrous 

metal oxides (for example: iron, aluminum, and manganese) 

and clay minerals commonly occur as coatings on other minerals and are important sources or sinks for arsenic (Smedley and 

Kinniburgh, 2001; Foster, 2003). Organic matter, wood preservatives, swine and poultry feed or pharmaceuticals, glass production, pesticides, and waste-disposal sites can also be sources 

of arsenic. 

Arsenate (H3AsO4) and arsenite (H3AsO3) are the most 

common and stable forms of arsenic in ground water (Stollenwerk, 2003). Arsenate has an oxidation state of +5 [As (V)] and 

is the predominant form of arsenic in oxic waters. Arsenite has 

an oxidation state of +3 [As (III)] and is the predominant form 

of arsenic in reducing waters. Of the two, As (III) has been considered to be more toxic (U.S. Environmental Protection 

Agency, 1976) and more mobile. However, recent work suggests that most ingested As (V) can be reduced to As (III) 

(National Research Council, 1999). Both can adsorb and desorb 

from mineral surfaces and form protonated oxyanions in aqueous solutions that are pH dependent (Stollenwerk, 2003, p. 69).

The extent of arsenic adsorption and desorption is largely 

controlled by pH (Stollenwerk, 2003, p. 99-100). Although 

As (V) and As (III) adsorb over a wide pH range, As (V) is 

adsorbed much stronger at lower pH values; As (III) adsorption 

increases with higher pH and peaks at about pH 8 or 9. 

In order to better evaluate the distribution of arsenic in 

Pennsylvania ground water, the U.S. Geological Survey 

(USGS), in cooperation with the Pennsylvania Department of 

Health (PaDOH) and the Pennsylvania Department of Environmental Protection (PaDEP), began a study in 2005 to relate concentrations of arsenic to major aquifers. The eight-county northern-tier area of Pennsylvania (fig. 1) was selected as an area to 

examine on the basis of (1) previous work that identified elevated concentrations of arsenic in the unconsolidated and consolidated bedrock aquifers, and (2) the identification of elevated 

concentrations of arsenic in adjacent states with similar hydrology and geology. 

Purpose and Scope 

This report describes the occurrence and distribution of 

arsenic in ground water used for water supply (primarily 

domestic) across eight northern-tier counties of Pennsylvania–

Potter, Tioga, Bradford, Susquehanna, Wayne, Pike, Sullivan, 

and Wyoming–and compares the occurrence of arsenic in 

ground water among eight bedrock formations (bedrock aquifers) and the unconsolidated aquifers. 

The report is based on results of analyses of 166 well and 

3 spring samples collected from July 2005 to June 2006 by well 

or spring owners and the USGS. This report presents data for 

total and dissolved arsenic and arsenic species, field-waterquality data, and well construction and associated site data. The 

report describes methods used for obtaining the water samples 

and the quality control used to evaluate sample and laboratory 

bias and variability, as well as potential sample contamination. 

Geologic, esthetic, and (or) well characteristics (for example 

well depth) are analyzed to evaluate their relation to concentrations of total arsenic. 

The results of this study can help water suppliers and 

homeowners in Pennsylvania make informed decisions about 

the need for testing for arsenic in ground water. This is especially important because the controls on arsenic distribution and 

concentration are poorly understood, and remediation methods 
Introduction 3

TIOGA POTTER

PIKE

BRADFORD

WAYNE

SUSQUEHANNA

SULLIVAN

WYOMING

EXPLANATION

Northern-tier countiesOther Pennsylvania counties

76° 78°

80°

42°

40°

KILOMETERS 0 50 100

MILES 0 50 100

Figure 1. Location of the eight counties that comprise the study area, northern-tier counties of Pennsylvania.
4 Reconnaissance of Arsenic Concentrations in Ground Water in Eight Northern-Tier Counties of Pennsylvania 

for homeowners may require substantial cost and continued 

maintenance. This information also could be useful for the 

USEPA, the PaDEP, and the PaDOH in protecting human 

health.

Previous Work 

A large amount of work regarding arsenic in ground water 

has been conducted by the USGS (Welch and others, 2000a, 

2000b). Ohio and Illinois were extensively glaciated, resulting 

in thick unconsolidated aquifers and buried valleys. Water supplies are obtained in these valleys as well as in the underlying 

or adjacent bedrock aquifers. In northeastern Ohio, Matisoff 

and others (1982) investigated elevated concentrations of 

arsenic where a buried valley dissects a sandstone aquifer overlain by till. The authors suggested that arsenic was released 

from iron oxides under reducing conditions, possibly from 

methane gas from deep underground storage. Another possibility was that iron oxides had become unstable in a reducing environment created after a layer of surficial till restricted recharge 

to the aquifer. In southwestern Ohio, Thomas and others (2005) 

found that ground-water samples with elevated concentrations 

of arsenic collected from glacial deposits and carbonate bedrock had at least one common factor–iron concentrations were 

greater than 1,000 μg/L. Thomas and others also hypothesized 

that arsenic was released from iron oxides under reducing conditions (by reductive dissolution or reductive desorption). 

Warner (2001) and Kelly and others (2005) investigated 

sand-and-gravel glacial aquifers in central Illinois and found 

considerable spatial variability in the arsenic concentrations, 

even in areas as small as 0.5 mi2

. Kelly and others (2005) also 

noted the solubility of arsenic was controlled by oxidationreduction conditions. It appeared that elevated concentrations 

of arsenic were associated with high concentrations of iron, 

bicarbonate, total organic carbon, and ammonia nitrogen and 

low concentrations of sulfate, chloride, and manganese. 

The presence of arsenic in ground water may have its origins in episodic periods of mountain building. Goldhaber and 

others (2003, p. 127) mention the effect of “...large-scale 

hydrothermal fluid migration events in the central and eastern 

United States ... ” on arsenic enrichment of pyrite in the bedrock aquifers and correlate them to the late stages of the Ouachita and Appalachian orogenies. In New England, many of the 

mountains consist of igneous (granite) or metamorphic (schist 

or gneiss) rocks enriched in minerals like pyrite. By analyzing 

rock lithologies and arsenic concentrations, Ayotte and others 

(1999, 2003) suggest that the major source of arsenic is naturally occurring and strongly correlated to the underlying geology.

Detectable concentrations of arsenic are relatively common throughout Pennsylvania; elevated concentrations also are 

found (Low and Chichester, 2006). Moore (1995) found elevated concentrations of arsenic in the sands along the shores of 

Lake Erie. Moore and Buckwalter (1996) determined that areas 

with a history of oil and gas drilling tended to have elevated 

concentrations of arsenic in the ground water. Much of this 

association, however, may be the result of improperly abandoned oil and gas wells. Taylor and Werkheiser (1984) found 

greater concentrations of arsenic in several members of the 

Catskill Formation than in the other units sampled. Taylor 

(1984), Taylor and others (1983), and Williams and others 

(1998) found that arsenic was more common in water from 

wells in glaciated valleys and shaley bedrock units than in wells 

completed on ridges and hilltops that penetrated bedrock units 

dominated by sandstone. They also reported that wells drilled in 

major valleys to depths much greater than 100 to 200 ft could 

penetrate sodium chloride or saline type water. Recent work by 

Mark Stephens (Pennsylvania Department of Environmental 

Protection, oral commun., 2006) in northeastern Tioga County 

indicates an association between arsenic and brine leaking from 

a borehole drilled to a depth below the freshwater aquifers. 

Mark Stephens also noted a possible association between 

arsenic and methane gas, and deep drilling for natural gas is 

more common now (2006) than in the recent past for many of 

the counties in the northern tier of Pennsylvania.

Description of Study Area 

The study area (fig. 1) covers 5,028 mi2 in eight counties–

Potter, Tioga, Bradford, Susquehanna, Wayne, Pike, Sullivan, 

and Wyoming–in the north-central and northeastern parts of 

Pennsylvania (northern-tier counties) and lies within the Appalachian Plateaus Physiographic Province and the Ridge and 

Valley Physiographic Province (Berg and others, 1989). The 

northern-tier counties are underlain by sedimentary rocks that 

range in age from Silurian to Pennsylvanian (table 1). The three 

most extensive bedrock units are the Catskill, Lock Haven, and 

Huntley Mountain Formations. The remaining units individually make up less than 10 percent of the underlying bedrock 

(fig. 2). 

Most of the bedrock formations are covered in part by 

unconsolidated glacial deposits (predominantly sand, gravel, 

and till) (fig. 3). This material ranges in thickness from a few 

feet on hilltops to more than 100 ft in major valley bottoms 

(Berg and others, 1980, fig. 1; Williams and others, 1998). 

Land cover in the eight counties is diverse. Land-cover 

data show that forest is dominant (53-88 percent), followed by 

agriculture (19-32 percent) (Taylor and others, 1983; Taylor, 

1984; Davis, 1989). Wetlands, urban (residential, commercial, 

industrial), other (barren, mines, quarries), and water represent 

the remaining land uses. The distribution of these land-cover 

types varies across the eight-county area as topography, physiography, and agricultural practices vary. 

Geohydrology 

The eight-county area has been broadly folded, uplifted, 

and repeatedly glaciated. Acceptable quantities (3 gal/min or 

greater for domestic wells) of ground water can be found in the 

bedrock aquifers and in valleys where thick unconsolidated
Introduction 5

TIOGA POTTER

PIKE

BRADFORD

WAYNE

SUSQUEHANNA

SULLIVAN

WYOMING

EXPLANATION

Bedrock Geology

Red sedimentaryShale

Quartzite, sandstone, and conglomerate

Bituminous coal bearingAnthracite coal bearing

County boundaries

Huntley Mountain Formation Catskill Formation

Lock Haven Formation

78°

42°

77° 76°

41°30'

MILES 0 25 50

KILOMETERS 0 25 50

Modified from Berg and others, 1980

Figure 2. The generalized bedrock geology of the study area, northern-tier counties of Pennsylvania.
6 Reconnaissance of Arsenic Concentrations in Ground Water in Eight Northern-Tier Counties of Pennsylvania TIOGA POTTER PIKE BRADFORD WAYNE SUSQUEHANNA SULLIVAN WYOMING EXPLANATION Not glaciated Valley fill County boundaries MILES 0 25 50 KILOMETERS 0 25 50 78° 77° 76° 41°30' Modified from Sevon and Braun, 2000 Wisconsin extent 42° Figure 3. The extent of the Wisconsin ice sheet and major valley fill deposits in the study area, northern-tier counties of Pennsylvania.
Introduction 7

sequences of sand and gravel exist (Williams and others, 1998). 

In certain areas, wells drilled in major valleys that exceed a 

depth of 100 to 200 ft may encounter brine-rich or saline water 

(Williams and others, 1998). 

Bedrock Aquifers

The Lock Haven Formation of Devonian age underlies 

1,141 mi2 and crops out in six counties (fig. 2). The Lock Haven 

Formation is a marine shale comprised of light-olive-gray to 

gray, thin to medium, inter-bedded, very-fine grained sandstone, siltstone, and silty shale; a few conglomerate beds occur 

near the top. The Lock Haven Formation is moderately resistant 

to weathering and forms hills and ridges of moderate relief 

slopes (Geyer and Wilshusen, 1982). 

The Lock Haven Formation is known for its brackish or 

saline water and the presence of hydrogen sulfide (Geyer and 

Wilshusen, 1982). Williams and others (1998) described 23 

wells in the Lock Haven Formation that produced sodium-chloride type or saline water, including 1 well that produced brine. 

These waters represent areas where ground-water flow is controlled in part by low-permeability material and where sodium 

and chloride are dominant anions. These wells ranged in depth 

from 99 to 720 ft. Saline water was reported by well owners or 

confirmed by water-quality analysis at depths that ranged from 

95 to 290 ft. 

The Catskill Formation of Devonian age overlies the Lock 

Haven Formation. The Catskill Formation and its members 

cover 2,945 mi2 in all eight counties (fig. 2). The Catskill Formation is a complex unit consisting of various amounts of gray 

to red shale, siltstone, sandstone, and conglomerate. Shales 

weather rapidly; sandstone, siltstone, and conglomerate are 

moderately resistant to weathering and break up into medium to 

large blocks. In Pike and the southern part of Wayne Counties, 

the Pennsylvania Topographic and Geologic Survey has 

divided the Catskill Formation into a series of members – Duncannon, Packerton, Poplar Gap, Towamensing, and Walcksville. Alternating or interbeds of gray to red shales, siltstones, 

sandstones, and, on occasion, conglomerate are common in 

these members (Berg and others, 1980). The Catskill Formation 

forms plateaus of medium relief with stable steep slopes (Geyer 

and Wilshusen, 1982). 

Although the Catskill Formation produces water that is 

generally soft and acceptable for most uses, elevated concentrations of iron, manganese, and total dissolved solids are present 

locally. Williams and others (1998) identified 15 wells from 

which saline water was produced from restricted-flow zones. 

These wells ranged in depth from 65 to 580 ft below land surface. The top of the restricted-flow zones were encountered at 

depths that ranged from 65 to 400 ft. 

The Huntley Mountain Formation of Mississippian and 

Devonian age overlies the Catskill Formation. The Huntley 

Mountain Formation covers 892 mi2 in five counties (fig. 2). 

The Huntley Mountain Formation is made up of two sandstone 

sequences. The upper unit is a tan to olive, fine- to mediumgrained, iron-stained, quartzitic sandstone with a conglomerate 

in the upper part. The lower unit is gray to tan, fine-grained, 

argillaceous sandstone. Both units contain interbeds of shale 

and mudstone. The sandstone is moderately resistant to weathering, forming flanks of steep valley walls of incised plateaus 

(Geyer and Wilshusen, 1982). Although the Huntley Mountain 

Formation yields water acceptable for most uses, the iron concentration may be high. 

Unconsolidated Aquifers

Glacial and postglacial valley-fill sediments consist of till, 

stratified drift, alluvium, and swamp deposits. Stratified drift 

includes ice-contact deposits, lacustrine and deltaic deposits, 

and outwash. Alluvium and swamp deposits compose the postglacial material (Williams and others, 1998). Thickness of the 

unconsolidated aquifers ranges from a few feet in upland areas 

to more than 100 ft in major valleys. Water sufficient to meet 

domestic needs can be obtained from wells almost anywhere 

Table 1. Generalized geologic column and dominant rock type(s), northern-tier counties in Pennsylvania.

System Dominant rock type(s) Group, Formation, or Member

Quaternary Sand, gravel, till Glacial deposits

Pennsylvanian Anthracite coal bearing Pottsville and Lewellyn Formations

Pennsylvanian Bituminous coal bearing Pottsville Formation and Allegheny Group

Mississippian and Devonian Red sedimentary (siliciclastics) Mauch Chunk Formation; Catskill Formation;

Long Run, Walcksville, and Duncannon 

Members of the Catskill Formation

Mississippian and Devonian Quartzite, sandstone, and conglomerate Pocono and Burgoon Formations; Huntley 

Mountain Formation; Packerton, Poplar 

Gap, and Towamensing Members of the 

Catskill Formation; Trimmers Rock Formation; Mahantango Formation

Mississippian and Devonian Shale Shenango through Oswayo Formations; 

Chadakoin Formation; Lock Haven Formation; Marcellus Formation
8 Reconnaissance of Arsenic Concentrations in Ground Water in Eight Northern-Tier Counties of Pennsylvania 

there is sufficient thickness (more than 10 ft) of unconsolidated 

material. However, these sediments are more susceptible to surface pollution and commonly yield water that is hard and has 

elevated concentrations of iron and manganese.

Williams and others (1998) identified six wells (four wells 

in stratified drift, two wells in till) that produced saline water 

from restricted-flow zones. The depths of these wells ranged 

from 58 to 119 ft. The top of the restricted-flow zones ranged 

from 58 to 115 ft.

Water Use 

The largest consumers of ground water in the study area 

are public water suppliers, mineral producers, and industry 

(Davis, 1989; Taylor, 1984; Taylor and others, 1983; Williams 

and others, 1998). Public water systems generally are confined 

to the larger municipalities or residential subdivisions. In 2006, 

approximately 161,000 people (52.9 percent) were served by 

private wells in the northern-tier counties (Arianne Proctor, 

Pennsylvania Department of Environmental Protection, written 

commun., 2006; U.S. Census Bureau, 2006). Much of the projected population growth will occur outside the major municipalities; hence, the use of private wells will need to increase to 

meet domestic requirements. 

Methods of Study 

Sampling Design 

Arsenic is widely dispersed in the rocks and unconsolidated sediments of Pennsylvania, and areas with water containing elevated concentrations of arsenic are difficult to identify. 

By having homeowners collect water samples, a large geographic area could be sampled and greater efforts could be 

directed toward those sites that contained concentrations of 

total arsenic above the MCL of 10 μg/L. 

The Information Office of the USGS Pennsylvania Water 

Science Center prepared a document describing the goals of the 

study and the reasons why it was important to evaluate the presence of arsenic in ground water. The document was released in 

March 2006 via public-service announcements through 55 radio 

stations and 34 daily or community newspapers and encouraged 

well owners to participate in the study.

Well and Spring Owner Participation and Sampling

Each well or spring owner who chose to participate in the 

study received an individual packet that contained (1) a letter 

explaining the study further and listing contacts for more information; (2) a questionnaire regarding well construction (well 

depth, casing length, date well drilled, and driller name); (3) a 

questionnaire regarding water treatment (sediment filter, water 

softener, reverse osmosis, or ultra-violate light), water problems (smell, taste, color, or staining), and length of use (appendix 1); (4) a 125 mL plastic sample bottle; (5) a set of directions 

for sampling, and (6) a postage-paid envelope to return the bottle to the USGS Pennsylvania Water Science Center. 

Requests to participate began to arrive within days of the 

public-service announcement in March and continued into June 

2006. A limit of approximately 25 samples per county initially 

was established to ensure that sufficient samples were collected 

from all eight counties. Because of the low response, an additional effort was put forth to contact well and spring owners 

through various county health agencies, the Pennsylvania State 

Agricultural Extension Agents, County Conservation Districts, 

the Pennsylvania Master Well Owner Network (MWON), and 

the PaDEP Office in Williamsport, Pa. By the end of June 2006, 

a total of 169 ground-water samples was delivered to the USGS 

Pennsylvania Water Science Center for processing and analysis. In almost all cases, the samples did not pass through any 

treatment system such as water softeners or filters.

Water samples that arrived at the USGS Pennsylvania 

Water Science Center were logged in, reviewed for completeness of the questionnaire, and acidified to a pH of less than 2 

using approximately 1.5 mL of nitric acid (7.7 normality tracemetal quality). The data from the questionnaires were entered 

into a spreadsheet. The samples were then delivered to the 

PaDEP laboratory for analysis of total arsenic. 

Targeted Sampling

Water samples were collected for analysis of total arsenic 

from 15 wells by the USGS. Five of the samples were collected 

in July 2005 in the vicinity of Tioga Junction, Pa., as part of 

another ground-water study in Tioga County, to evaluate field 

and laboratory methods for collecting, processing, and analyzing samples for dissolved-arsenic speciation. On June 14 and 

15, 2006, the remaining 10 samples were collected for analysis 

of total arsenic in areas where elevated concentrations of total 

arsenic had already been confirmed by a previous well owner 

sample. USGS collection methods for samples analyzed for 

total arsenic were identical to the methods homeowners were 

requested to follow. An additional seven samples were collected by the USGS for dissolved arsenic, arsenite (As III), 

arsenate (As V), monomethylarsonate (MMA), and dimethylarsinate (DMA), hereafter termed arsenic species, at wells containing water with concentrations of total arsenic greater than 

10 μg/L. 

Procedures for collecting water for analyses of dissolved 

arsenic and arsenic species were more rigorous than that 

required for collecting samples for total arsenic. Before collection of any samples, wells were pumped at a constant discharge 

rate of approximately 3 gal/min for a minimum of 20 minutes. 

The low pumping rate and duration of pumping were based on 

(1) the desire not to stress the well beyond normal use; (2) daily 

use of the well (hence, good connection with the aquifer 

because the water in the borehole is constantly being replaced); 

and (3) the field measurements becoming stabilized after 
Laboratory Procedures and Quality Control 9

20 minutes. Discharge water was monitored for temperature, 

dissolved oxygen, specific conductance, pH, and oxidationreduction potential (to convert oxidation-reduction potential to 

Eh, add 200 millivolts) using a multi-parameter instrument and 

flow-through chamber. Once the field measurements were stable (within 5 percent of the last reading) or after pumping the 

well a minimum of 20 minutes, water from the discharge spigot 

was pumped through an acid-rinsed disposable capsule filter 

with pore size of 0.45 μm into sample bottles. Water to be analyzed for arsenic species and for dissolved arsenic was collected 

in a 10 mL amber-colored plastic bottle and a 250 mL translucent, acid-rinsed plastic bottle, respectively. 

For sample preservation, water for analysis of dissolved 

arsenic was acidified with nitric acid (7.7 normality, trace-metal 

quality) to a pH of less than 2. Water for analysis of arsenic species was preserved with 100 μL ethylenediaminetetraacetic acid 

(EDTA) (Garbarino and others, 2002; Wilde and others, 2004). 

Bottles were immediately placed in an ice-filled cooler and later 

transferred to laboratory refrigerators. Bottles were shipped on 

ice via overnight delivery to the USGS National Water Quality 

Laboratory (NWQL) within a week of collection for analysis.

Laboratory Procedures and Quality Control

Concentrations of unfiltered (total) arsenic were determined at the PaDEP laboratory using an inductively coupled 

plasma-mass spectrometer (ICP/MS) and USEPA method 

200.8, Revision 5.4; the minimum reporting level of the instrument was 4.0 μg/L.

Quality control (QC) at the PaDEP laboratory was maintained by utilizing 100 μg/L standards, 100 μg/L fortified 

blanks, 100 μg/L fortified matrix samples, and 100 and 

400 μg/L calibration standards. QC of samples submitted was 

maintained by using 5 replicate samples, 7 metal-free samples, 

and 14 standard reference water samples (SRWS). SRWS are 

created at the NWQL to evaluate laboratory capabilities to 

accurately quantify analyte concentrations. SRWS contain 

known concentrations of selected trace metals and other analytes. The SRWS selected for this study was T-135, which contained 10 μg/L arsenic. Any contamination during sample collection and analysis was determined through analytical results 

from metal-free samples. Replicate samples helped to test the 

inherent variability of arsenic due to laboratory or sampling 

methodology. T-135 helped to determine inherent bias in the 

sampling or analytical procedures. 

Concentrations of dissolved arsenic and arsenic species 

were determined at the NWQL by collision reaction cell inductively coupled plasma-mass spectrometry (cICP/MS) using 

USGS method I-2020-5 (Garbarino and others, 2002, 2006). 

The method detection limit was 0.12 μg/L.

QC samples submitted to NWQL for analysis of dissolved 

arsenic and arsenic species were prepared according to standard 

USGS protocols (Wilde and others, 2004). The QC samples for 

dissolved arsenic consisted of one replicate sample and two 

SRWS. The QC samples for arsenic species consisted of one 

metal-free, one replicate, one SRWS, and one matrix-spike 

sample. Replicate samples were collected immediately after the 

routine samples in the field using the same collection methods 

and equipment.

The relative percent difference (RPD) was determined for 

replicate samples, for which results (for both the original and 

replicate sample) were greater than the reporting limit, to determine if PaDEP laboratory precision met the guidance criteria of 

less than or equal to 20 percent difference. The RPD calculation 

was as follows:

RPD (%) = [S – D] / ((S + D)/2) x 100, (1)

where 

S is original sample result, 

D is replicate sample result, and 

[ ] is absolute value 

To evaluate the magnitude of the variability for triplicate 

samples (in this case, three SWRS), a calculation of percent relative standard deviation (% RSD) was determined. The goal is 

for recoveries to be within +/-20 percent. The % RSD was calculated as follows:

standard deviation of the triplicate recovery results % RSD = (2) ( X 100. mean concentration of the triplicate recovery results)

Percent recovery was determined for blank-spike samples 

(submitted only to NWQL) by dividing the measured concentration by the theoretical concentration and multiplying this 

product by 100. The theoretical concentration for matrix-spike 

samples was determined by mixing a known volume of a field 

sample (with a known concentration) with a known volume of 

a standard-reference solution. Percent recoveries under 100 percent indicate that the laboratory underestimated the theoretical 

concentration; a percent recovery above 100 percent indicates 

an overestimation. 

QC samples submitted to the PaDEP laboratory are summarized in table 2. There were no detections for any metal-free 

samples submitted to the laboratory. Recoveries of total arsenic 

in SRWS exhibited a negative bias, indicating the laboratory 

typically did not recover all the total arsenic in the sample; however, the RPD for SRWS ranged from 0.0 to 4.2 percent, well 

within the acceptable limit. All replicate pairs submitted to the 

PaDEP laboratory had arsenic concentrations less than 

4.0 μg/L; therefore, the replicate analysis did not indicate any 

problems with precision or variability in the laboratory methodology at the minimum detection level. The variability (% RDS) 

in triplicate SRWS submitted to the laboratory were well within 

the acceptable range of +/-20 percent (table 2).

QC samples submitted to the NWQL are summarized in 

table 3. No arsenic species were detected in the blank sample 

submitted to the NWQL. The SRWS submitted showed a slight 

positive bias for dissolved arsenic. The SRWS for arsenic speciation showed a slight negative bias because the mean recovery 

for the different arsenic species was 98 percent. The difference 

measured in concentrations between the one replicate pair submitted for dissolved arsenic analysis was well within the precision (+/- 20 percent) of the methods used (table 3).
10 Reconnaissance of Arsenic Concentrations in Ground Water in Eight Northern-Tier Counties of Pennsylvania 

Table 2. Results of quality control for analyses of total-arsenic concentration, Pennsylvania Department of

Environmental Protection Laboratory.

[--, not applicable; μg/L, micrograms per liter; <, less than; RSD, relative standard deviation; RPD, relative percent difference;

SRWS, USGS-Standard Reference Water Sample T-135]

Sample

type

Date

SRWS Theoretical

concentrations,

(μg/L)

Measured

concentration, 

(μg/L)

RPD, 

in percent

RSD, 

in percent

Replicate Samples

Well Original 04/03/2006 -- < 4.0 -- --

Well Replicate 04/03/2006 -- < 4.0 0 --

Well Original 04/10/2006 -- < 4.0 -- --

Well Replicate 04/10/2006 -- < 4.0 0 --

Well Original 05/03/2006 -- < 4.0 -- --

Well Replicate 05/03/2006 -- < 4.0 0 --

Well Original 03/29/2006 -- < 4.0 -- --

Well Replicate 03/29/2006 -- < 4.0 0 --

Well Original 04/06/2006 -- < 4.0 -- --

Well Replicate 04/06/2006 -- < 4.0 0 --

Blank Samples

Metal Free 04/13/2006 0.0 < 4.0 -- --

Metal Free 04/13/2006 .0 < 4.0 -- --

Metal Free 04/24/2006 .0 < 4.0 -- --

Metal Free 05/10/2006 .0 < 4.0 -- --

Metal Free 05/23/2006 .0 < 4.0 -- --

Metal Free 05/23/2006 .0 < 4.0 -- --

Metal Free 06/06/2006 .0 < 4.0 -- --

Reference Samples

SRWS 04/18/2006 10.0 9.2 4.2 --

SRWS 05/23/2006 10.0 9.3 3.6 --

SRWS 06/24/2006 10.0 9.2 4.2 --

SRWS 04/24/2006 10.0 9.2 4.2 --

SRWS 04/20/2006 10.0 9.4 3.9 --

SRWS 06/06/2006 10.0 9.8 1.0 --

SRWS 04/18/2006 10.0 9.2 4.2 --

SRWS 06/24/2006 10.0 9.4 3.9 --

Triplicate Samples

SRWS triplicate 04/12/2006 10.0 10.7 3.4 7.3

SRWS triplicate 05/10/2006 10.0 10.4 2.0 7.3

SRWS triplicate 05/10/2006 10.0 10.0 .0 7.3

SRWS triplicate 05/10/2006 10.0 10.2 1.0 .4

SRWS triplicate 04/13/2006 10.0 9.8 1.0 .4

SRWS triplicate 04/13/2006 10.0 10.5 2.4 .4
Arsenic Concentrations in Ground Water 11

Arsenic Concentrations in Ground Water 

Water from 158 domestic wells, 2 stock wells, 4 non-community wells, 2 community water-system wells, and 3 domestic 

springs in the northern-tier counties of Pennsylvania were analyzed for total arsenic (appendix 2). Detectable concentrations 

(4.0 μg/L or greater) of arsenic were measured in the water from 

18 wells (10.8 percent) from four counties–Bradford, Sullivan, 

Tioga, and Wayne. Arsenic was not detected in any of the three 

sampled springs. Concentrations of total arsenic ranged from 

less than 4 μg/L to 188 μg/L; the median was less than 

4.0 μg/L. Water from 10 wells (6.0 percent) sampled had concentrations of total arsenic greater than the USEPA MCL of 

10 μg/L. The distribution of sampled sites and the range of total 

arsenic in the water from each well and spring are shown in figure 4. The number of samples collected per county varied considerably (fig. 4 and table 4). 

Reconnaissance of Total-Arsenic Concentrations 

Arsenic was detected in the water from three wells in Bradford County–BR-873, BR-855, and BR-854; the concentrations 

of total arsenic were 5.3, 39.4, and 117 μg/L, respectively. The 

two wells containing water with the highest concentrations of 

total arsenic are on slopes and are completed in the Lock Haven 

Formation at depths of 250 and 256 ft, respectively. 

Arsenic was detected in the water of one well in Sullivan 

County; the concentration of total arsenic was 9.8 μg/L. This 

well, SU-135, is on a slope and is completed in the Catskill Formation at a depth of 400 ft.

The largest number of samples submitted was from wells 

in Tioga County (figs. 4 and table 4). This heightened interest is 

probably the result of an incident of arsenic contamination in a 

small community in northeast Tioga County (fig. 5). A commercial well encountered saline water at a depth of about 223 ft.

Table 3. Results of quality control for analyses of dissolved arsenic and arsenic species, U.S. Geological 

Survey National Water Quality Laboratory.

[SRWS, USGS-Standard Reference Water Sample T-135; μg/L, micrograms per liter; --, not applicable; RPD, relative percent 

difference; E, estimated; <, less than]

Sample type

Theoretical 

concentration,

(μg/L)

Measured

concentration,

(μg/L)

RPD, 

in percent

Percent

recovery

Well original -- 175 -- --

Well replicate -- 178 -1.7 --

SRWS 10.0 10.3 -3.0 --

SRWS 10.0 10.2 -2.0 --

Blank 

Arsenite .0 <.6 -- --

Arsenate .0 <.6 -- --

Monomethylarsonate .0 <1.2 -- --

Dimethylarsinate .0 <.6 -- --

Blank spike

Arsenite 21.7 21.0 -- 97

Arsenate 21.7 21.1 -- 97

Monomethylarsonate 21.7 22.1 -- 102

Dimethylarsinate 21.7 20.6 -- 95

Original

Arsenite -- 14.1 -- --

Arsenate -- E .6 -- --

Monomethylarsonate -- <1.2 -- --

Dimethylarsinate -- <.6 -- --

Matrix spike

Arsenite 35.6 35.4 -- 99

Arsenate 22.3 22.0 -- 99

Monomethylarsonate 21.7 21.3 -- 98

Dimethylarsinate 21.7 21.7 -- 100
12 Reconnaissance of Arsenic Concentrations in Ground Water in Eight Northern-Tier Counties of Pennsylvania TIOGA POTTER PIKE BRADFORD WAYNE SUSQUEHANNA SULLIVAN WYOMING County boundaries EXPLANATION Arsenic concentrations of sampled sites, in micrograms per liter Less than 4.0 Between 4.0 and 10.0 Greater than 10.0 MILES 0 25 50 KILOMETERS 0 25 50 78° 77° 42° 41°30' 76° Figure 4. The location of sampled sites and ranges of total-arsenic concentrations, northern-tier counties of Pennsylvania.
Arsenic Concentrations in Ground Water 13

The well was abandoned because of the presence of saline 

water, but the well was not immediately plugged after abandonment. As a result of hydrostatic pressure, this saline water 

flowed upward into the shallow bedrock and unconsolidated 

aquifers that supplied water to nearby domestic wells. Unfortunately, the saline water was enriched in arsenic and contaminated approximately 10 wells (Mark Stephens, Pennsylvania 

Department of Environmental Protection, oral commun., 2006). 

Another possible factor for the large number of samples submitted from Tioga County is the increase in deep gas drilling in the 

county and concern that domestic wells may be adversely 

affected by this activity. The distribution of the sites in Tioga 

County is shown in more detail in figure 5.

Arsenic was detected in the water from 13 wells in Tioga 

County; the concentrations of total arsenic in these wells ranged 

from 4.0 to 53.8 μg/L; the median was 13.0 μg/L. Well depths 

in these 13 wells ranged from 29 to 175 ft; the median was 112 

ft (fig. 6). Only two wells–TI-670 and TI-704–are on slopes; the 

remaining wells are in valleys. The concentrations of arsenic in 

the water of the two slope wells were 34.4 and 4.0 μg/L, respectively. Two wells–TI-576 and TI-668–are completed in the 

unconsolidated aquifers; the concentrations of total arsenic 

were 47.6 and 14.4 μg/L, respectively. One well–TI-704–is 

completed in the Catskill Formation. The remaining wells are 

completed in the Lock Haven Formation. 

Total arsenic was detected in the water from one well in 

Wayne County; the arsenic concentration was 188 μg/L, the 

highest measured. This well, WN-135, is on a slope and is completed in the Catskill Formation at a depth of 340 ft. As a result 

of the elevated concentration of total arsenic, two wells within 

0.5 mi and downslope of WN-135 were sampled. Arsenic was 

not detected in these two wells at the reporting limit of 4.0 μg/L.

Figure 6 shows the distribution of total arsenic to well 

depth. Two of the three deepest wells (WN-135 and BR-854) 

contain water with the highest concentrations of arsenic. This 

suggests that concentrations of arsenic increase with well depth. 

However, contingency tables did not support such an interpretation. 

Relation of Total Arsenic to Geology 

The presence of arsenic in ground water of the northerntier counties is strongly related to bedrock geology. Arsenic was 

detected with greater frequency in the water of wells completed 

in the Lock Haven Formation than in the water of wells completed in other formations that underlie the study area. 

The Lock Haven Formation was represented by 60 wells. 

Water from 12 of the 60 wells (20 percent) had detectable concentrations of arsenic. Where detected in the water of sampled 

wells, total-arsenic concentrations ranged from 4.5 to 117 μg/L; 

the median was 14.2 μg/L. 

The Catskill Formation was represented by 57 wells. 

Water from 4 of the 57 wells (7 percent) contained detectable 

concentrations of arsenic. The measured concentration of total 

arsenic in water from the Catskill Formation were 4.0, 5.3, 9.8, 

and 188 μg/L. 

The unconsolidated aquifers were represented by 17 wells. 

Water from 2 of the 17 wells (12 percent) contained detectable 

concentrations of arsenic. The measured concentrations of total 

arsenic in water from the unconsolidated aquifers were 14.4 and 

47.6 μg/L. 

Contingency tables were generated to evaluate the presence of total arsenic in the bedrock and unconsolidated aquifers. 

Total arsenic was found, at the 95-percent confidence level, 

with statistically greater frequency (chi-square of 0.0020) in the 

Lock Haven Formation than in the other bedrock aquifers. Total 

arsenic in the Lock Haven Formation also was found with statistically greater frequency if the well was located in a valley, as 

compared to a slope (chi-square of 0.0038) or a hilltop (chisquare of 0.0171). Although total arsenic also was found in 

water samples from wells in the unconsolidated aquifers and the 

Catskill Formation, the frequency of detections was not statistically significant. The frequency of total arsenic did not vary significantly by well depth for any aquifer.

Table 4. Number of well and spring samples collected for total-arsenic analysis and water use, northern-tier counties of Pennsylvania.

County

Number of 

well samples

Number of 

spring samples

Water use

Domestic Non-community Community Stock

Bradford 22 1 21 0 0 1

Pike 25 0 22 3 0 0

Potter 10 0 10 0 0 0

Sullivan 14 1 12 1 0 1

Susquehanna 4 0 4 0 0 0

Tioga 65 1 63 0 2 0

Wayne 15 0 15 0 0 0

Wyoming 11 0 11 0 0 0
14 Reconnaissance of Arsenic Concentrations in Ground Water in Eight Northern-Tier Counties of Pennsylvania EXPLANATION Tioga County Boroughs Arsenic concentrations at sampled sites, in micrograms per liter 77°15' 77°30' MILES 0 10 20 KILOMETERS 0 10 20 42° 77° Note: The county abbreviation (TI) that should precede the displayed local well or spring numbers was omitted. 669 576 670 667 681 668 683 721 677 696 704 723 722 720 719 717 716 714 713 544 711 710 709 708 707 705 706 703 702 671 701 700 699 698 697 695 694 693 692 691 690 689 688 687 686 685 684 679 674 673 580 672 579 578 577 122 120 SP-3 WELLSBORO ELKLAND WESTFIELD TIOGALIBERTYROSEVILLE TIOGA COUNTY BLOSSBURG MANSFIELD KNOXVILLE LAWRENCEVILLE 692 721 670 Local well or spring number and concentration less than 4.0 Local well number and concentration between 4.0 and 10.0 Local well number and concentration greater than 10.0 718 715 682 680 678 676106 675 41°45'

Figure 5. The location of sampled sites and ranges of total-arsenic concentrations in Tioga County.
Arsenic Concentrations in Ground Water 15

Relation of Total Arsenic to Iron Staining and 

Hydrogen Sulfide

Trace to objectionable amounts of iron and hydrogen sulfide have been associated with the presence of arsenic (Mueller 

and others, 2001; Warner, 2001; Kelly and others, 2005; Thomas and others, 2005). A quantitative measurement of iron and 

hydrogen sulfide was beyond the scope of this study. Instead, a 

questionnaire (appendix 1) was used to obtain qualitative observations from the owner of the well or spring on the presence or 

absence of iron staining and (or) hydrogen-sulfide odor. All 

well and spring owners were requested to note “yes” if their 

drinking water had an objectionable stain or odor problem. Out 

of 169 samples, 44 well owners (26 percent) complained of iron 

staining, 35 well owners (21 percent) complained of hydrogensulfide odor, and 14 well owners (8 percent) complained of 

both. These observations are presented for only those wells with 

detectable concentrations of total arsenic in table 5. Contingency tables did not indicate a statistical correlation between 

the presence or absence of iron staining and (or) hydrogen-sulfide odor to the existence of arsenic in these wells.

Redox Conditions and Concentrations of Arsenic 

Species

The distribution of arsenic species in ground water is controlled by various geochemical conditions, in particular the 

reducing and oxidizing (redox) environment. On the basis of 

samples collected in Germany, Tretner and others (2006) concluded that distribution of arsenic species is affected by three 

factors – (1) input species of arsenic, (2) availability of reaction 

partners during soil and ground-water passage, and (3) the 

redox conditions in the ground-water environment. Mueller and 

others (2001) noted that As (III) correlated well with concentrations of dissolved oxygen that reflect strongly reducing conditions (< 0.1 mg/L). As (V) was associated with oxidizing conditions (dissolved oxygen > 8 mg/L). 

The organic or methylated forms of arsenic, MMA and 

DMA, are not common in natural waters (table 6). These 

organic forms of arsenic are normally present in highly reducing environments where a source of carbon is present (Beth 

O’Shea, Dickinson College, written commun., 2006). Davis 

and others (1994) studied a highly reducing ground-water environment down gradient of a historical tannery in Massachusetts. 

Conditions were so reducing that dissolved organic carbon levels were extremely high (> 100 mg/L) from hide breakdown, 

leading to reduction of As (V) to As (III) and subsequent methylation by biosynthesis to MMA and DMA.

The field measurements made by USGS personnel during 

sampling for determinations of dissolved arsenic and arsenic 

species are listed in table 6. Water from all eight wells, except 

WN-210, was from the Lock Haven Formation or the unconsolidated aquifers. On the basis of the high pH and low dissolved 

oxygen and oxidation-reduction potential, water from the Lock 

Haven Formation and unconsolidated aquifers is the product of 

a reducing environment. It is in this type of environment that 

elevated concentrations of As (III) are expected. Well WN-210 

is completed in the Catskill Formation and produces water from 

an oxidizing environment that is characterized by low pH, and 

relatively high dissolved oxygen and oxidation-reduction 

potential. In this type of environment, As (V) is expected to be 

0 100 200 300 400

WELL DEPTH, IN FEET BELOW LAND SURFACE

0

50

100

150

200

Unconsolidated

Catskill Formation

Lock Haven Formation

TOTAL-ARSENIC CONCENTRATION, 

IN MICROGRAMS PER LITER 

10 micrograms per liter (Maximum Contaminant Level)

Figure 6. Distribution of total-arsenic concentration and well depth by geologic 

units, northern-tier counties of Pennsylvania. 
16 Reconnaissance of Arsenic Concentrations in Ground Water in Eight Northern-Tier Counties of Pennsylvania 

Table 5. Well depths and well-owner observations on the presence (or absence) of iron staining and (or)

hydrogen-sulfide odor for wells containing water with total-arsenic concentrations of 4 μg/L or greater, 

northern-tier counties of Pennsylvania.

[Analyses for total arsenic concentration by Pennsylvania Department of Environmental Protection Laboratory; well depth,

feet below land surface; μg/L, micrograms per liter; --, no data; 112ALVM, unconsolidated aquifers; 341CSKL, Catskill Formation; 

341LKHV, Lock Haven Formation]

U.S. Geological

Survey

well 

number

Geologic 

unit

Total arsenic

concentration

(μg/L)

Well depth

(feet)

Iron

staining

Hydrogensulfide odor

Iron staining and

hydrogensulfide odor

TI-576

TI-668

BR-873

SU-135

TI-704

WN-210

BR-854

BR-855

TI-667

TI-669

TI-670

TI-676

TI-677

TI-681

TI-682

TI-683

TI-696

TI-721

112ALVM

112ALVM

341CSKL

341CSKL

341CSKL

341CSKL

341LKHV

341LKHV

341LKHV

341LKHV

341LKHV

341LKHV

341LKHV

341LKHV

341LKHV

341LKHV

341LKHV

341LKHV

 47.6

 14.4

 5.3

 9.8

 4.0

 188

 117

 39.4

 16.0

 53.8

 34.4

 5.1

 6.9

 15.4

 9.0

 13.3

 4.5

 9.8

29

112

90

400

130

340

255

200

100

100

160

--

137

90

--

100

145

175

No

No

No

No

No

Yes

No

Yes

No

No

Yes

No

No

Yes

Yes

 No

Yes

Yes

No

No

Yes

No

No

No

No

Yes

No

No

No

No

No

Yes

Yes

Yes

No

No

No

No

No

No

No

No

No

Yes

No

No

No

No

No

Yes

Yes

 No

No

No
Summary 17

the dominant arsenic species. The results in the northern-tier 

counties on arsenic speciation support the conclusion of Tretner 

and others (2006) that As (III) is the dominant species in 

strongly reducing environments (< 0.1 mg/L dissolved oxygen) 

and As (V) is the dominant species in oxidizing environments 

(> 8 mg/L dissolved oxygen). 

Summary 

In July 2005 and from March through June 2006, the 

USGS, in cooperation with the Pennsylvania Department of 

Health and the Pennsylvania Department of Environmental Protection, measured concentrations of total arsenic in water samples from 166 wells and 3 springs in 8 counties in the northern 

tier of Pennsylvania. The median arsenic concentration was less 

than 4.0 μg/L, and the maximum was 188 μg/L. Detectable levels of total arsenic were measured in the water from 18 wells 

(11 percent), and 10 of the wells (6 percent) sampled contained 

water with concentrations of arsenic greater than the U.S. Environmental Protection Agency Maximum Contaminant Level of 

10 μg/L; none of the water samples from the springs contained 

detectable levels of arsenic. The greatest number of wells (12 of 

60 wells or 20 percent) producing water with detectable concentrations of arsenic were completed in the Lock Haven Formation. In the unconsolidated aquifers, 2 of 17 wells (12 percent) 

produced water with detectable concentrations of arsenic. In the 

Catskill Formation, 4 of 57 wells (7 percent) produced water 

with detectable concentrations of arsenic. Contingency tables 

for the three units containing detectable concentrations of 

arsenic indicate that arsenic is found with significantly greater 

frequency in the Lock Haven Formation than in the unconsolidated aquifers and the Catskill Formation. Topographic setting 

also significantly affected the frequency of total arsenic in the 

Lock Haven Formation, but not in the Catskill Formation. There 

was no significant difference in the frequency or concentration 

of total arsenic and well depth.

Previous studies in similar hydrogeologic environments 

have associated iron and sulfur with the presence of arsenic. 

Table 6. Dissolved arsenic and arsenic species concentrations and field-water-quality measurements for wells

that contain water with dissolved arsenic concentrations greater than 10 μg/L, northern-tier counties of Pennsylvania.

[Arsenic analyses by U.S. Geological Survey, National Water Quality Laboratory. As (III), arsenite; As (V), arsenate; MMA,

monomethylarsenate; DMA, dimethylarsenite; μS/cm, microsiemens per centimeter at 25 degrees Celsius;<, less than; E, estimated;

mg/L, milligrams per liter; °C, degrees Celsius; mv, millivolts; μg/L, micrograms per liter; 112ALVM, unconsolidated aquifers;

341CSKL, Catskill Formation; 341LKHV, Lock Haven Formation]

U.S.

Geological

Survey well 

number

Aquifer

Dissolved 

arsenic

(μg/L)

As (III)

(μg/L)

As (V)

(μg/L)

MMA 

(μg/L)

DMA

(μg/L)

BR-854 341LKHV 176 144.0 37.9 <1.2 <0.6

BR-855 341LKHV 40.1 38.7 1.6 <1.2 1.0

TI-576 112ALVM 47.6 37.3 6.7 E .9 1.5

TI-667 341LKHV 17.1 16.9 E .8 <1.2 <.6

TI-668 112ALVM 14.5 14.1 E .6 <1.2 <.6

TI-669 341LKHV 56.8 55.8 .8 <1.2 <.6

TI-670 341LKHV 35.5 28.2 7.9 <1.2 <.6

WN-210 341CSKL 27.6 1.8 33.2 <1.2 <.6

U.S.

Geological

Survey well 

number

Specific

conductance 

(μS/cm)

pH (standard

units)

Dissolved oxygen

(mg/L)

Temperature

(°C)

Oxidation

reduction

potential 

(mv)

Sulfur 

odor

BR-854 461 8.5 0.18 10.6 -99 No

BR-855 564 9.1 .29 10.0 -131 Yes

TI-576 244 8.2 .19 11.9 -203 Yes

TI-667 404 8.8 .18 11.4 -160 No

TI-668 332 8.5 .06 11.1 -70 Yes

TI-669 452 8.5 .16 11.4 -63 No

TI-670 632 8.6 .19 12.0 -128 No

WN-210 181 4.8 2.15 10.6 265 No
18 Reconnaissance of Arsenic Concentrations in Ground Water in Eight Northern-Tier Counties of Pennsylvania 

Although a quantitative analysis was beyond the scope of this 

project, a qualitative comparison was completed using homeowner response to the presence of iron and (or) hydrogen-sulfide odor. On the basis of the 18 wells producing water with 

detectable concentrations of arsenic and homeowner responses, 

objectionable quantities of iron, hydrogen-sulfide odor, and (or) 

both were found in 7 (39 percent), 5 (28 percent), and 3 (17 percent) of the wells, respectively. There was, however, no statistical correlation between iron staining and (or) hydrogen-sulfide odor and the presence of arsenic in these wells.

Dissolved arsenic, arsenic species, and related field-waterquality constituents were analyzed in water from one well in 

July 2005 and from seven wells in June 2006 that produced 

water with elevated arsenic concentrations (greater than 

10 μg/L). Field measurements of pH, dissolved oxygen, and 

oxidation-reduction potential indicated that seven of the eight 

wells produced water that represented reducing environments; 

these wells were completed in the Lock Haven Formation or the 

unconsolidated aquifers. In such an environment, As (III) was 

the dominant arsenic species. The remaining well, completed in 

the Catskill Formation, produced water that represented an oxidizing environment; in this water, As (V) was the dominant 

arsenic species. The arsenic species MMA and DMA are not 

commonly detected in natural waters but were found in the 

water from two wells. The arsenic species MMA was detected 

at an estimated concentration of 0.9 μg/L in water from one 

well; the concentration was less than 1.2 μg/L in water from 

seven wells. The arsenic species DMA was detected at concentrations of 1.0 and 1.5 μg/L in water from two wells; the concentration was less than 0.6 μg/L in water from six wells. Both 

wells that contained detectable concentrations of MMA and 

DMA produced water that was characteristic of reducing environments.

Acknowledgments 

The authors thank David Marchetto and Patricia Miller of 

the PaDOH and PaDEP, respectively, who provided a great deal 

of assistance in developing the project and providing input to 

USGS personnel as the project was being implemented. The 

authors also would like to acknowledge the assistance of Dennis 

Neuin of the PaDEP Laboratory for his work in analyzing the 

total-arsenic samples and the USGS National Water Quality 

Laboratory for assistance with arsenic speciation. We also 

extend thanks to our USGS colleagues Ronald Sloto, Joseph 

Ayotte, Kevin Breen, and Kim Otto for their detailed reviews of 

this report and suggestions regarding content and organization.

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Appendix 1 - U.S. Geological Survey 

Homeowner Questionnaire
22 Reconnaissance of Arsenic Concentrations in Ground Water in Eight Northern-Tier Counties of Pennsylvania 

STUDY PARTICIPATION INFORMATION

Name (Please Print)

Street Address

Mailing Address, if different

City, State, Zip Code

Telephone Number (day) Telephone Number (evening) Email

COMMON QUESTIONS

Why was my well chosen?

Your well is one of 200 wells that were randomly selected from a database of thousands in the study area.

What will this cost me?

Nothing. In fact, you will receive important information about the arsenic concentration in your drinking water. For more 

information on arsenic in drinking water contact:

Geisinger Health System – Steve Browning (570) 214-9727, srbrowning@geisinger.edu

PA Department of Environmental Protection Regional Offices – 

http://www.depweb.state.pa.us/dep/cwp/view.asp?a=3&q=461282

Northeast – (570) 826-2511 Northwest (815) 332-6945 Northcentral (570) 327-3636

Southeast - (484) 250-5900 Southwest (412) 442-4000 Southcentral (717) 705-4700

(Please ask for your Drinking Water Program staff when calling)

PA Department of Health – Cynthia Goodman (717) 787-1708, cygoodman@state.pa.us

U.S. Environmental Protection Agency – http://www.epa.gov/safewater/arsenic/index.html

U.S. Geological Survey – 

Dennis Low, USGS (717) 730-6959, djlow@usgs.gov 

Curtis Schreffler (717) 730-6913, clschref@usgs.gov
 23

From where is the sample collected?

Sample should be collected from a faucet or spigot that does not receive treated water (if you have a water treatment system). If 

you can not collect untreated water by using a by-pass valve in your plumbing we still would like a water sample from your well. 

Please just describe the treatment system on a separate sheet of paper.

How will the information be used?

These data will be summarized by town, township, county, geologic information, and other broad groups of variables. No 

individual information will be published. You will receive a copy of the report which summarizes the findings of this study in 

addition to your individual well water analysis results. 

SAMPLE COLLECTION (filled in by well owner)

1. Collect a sample from a faucet or outside spigot that does not receive treated or filtered water (check one):

Kitchen _____ Bathroom _____ Outside spigot _____ 

Spigot before pressure tank _____ Spigot after pressure tank _____

Other _____ Please explain _______________________________________________

If you are unable to collect an untreated water sample, please be sure to describe your treatment system below.

2. Allow the cold water to run for 2-3 minutes to clear the pipes. Reduce flow to a gentle stream.

3. Fill sample bottle with well water to just below the neck of the bottle. Make sure that the cap is securely tightened. 

4. Place the filled sample bottle in the mailer and place all paper work in the plastic, sealable envelope.

WELL INFORMATION (filled in by well owner)

1. Do you use your well water as drinking water? YES __ NO__ Cooking? YES__ NO__

2. Do you have any problems with your well water (odor/staining/amount)? 

YES__ NO__Please describe ______________________________________________

3. Do you have a treatment/filter system for your well water? YES__ NO__

4. What type of treatment do you use? (softener, reverse osmosis systems, green sand/birm filters, permanganate/potassium, ion 

exchange)

Other __________________________________________________________________

Appendix 1 
24 Reconnaissance of Arsenic Concentrations in Ground Water in Eight Northern-Tier Counties of Pennsylvania 

5. Is your treatment system designed for (circle any that apply): pH adjustment, Iron, Manganese, 

Arsenic, Radon, Sediment removal, other? ___________________________

6. Have you ever had your well tested for arsenic? YES________ NO __________

When __________ What was the concentration ____________

7. How deep is your well?__________

8. How many feet of casing does the well have?__________

9. Have you ever stopped drinking water from this well? YES_____ NO_____

If yes, why? (bacteria, nitrate, arsenic, other)_______________

10. How long have you been using the current well?__________

11. How long have you been drinking well water at your current location?__________

Please sign and date this page.

USGS Arsenic Project

215 Limekiln Road

New Cumberland, PA 17070

Homeowner name ___________________________________________, Date______

Received by ________________________________________________, Date _____
Appendix 2 - Records of selected wells and 

springs, northern-tier counties, Pennsylvania

Well or spring location: The number that is assigned by the U.S. Geological Survey to 

identify the well or spring (SP). It is prefixed by the two-letter abbreviation of the county. 

The latitude and longitude of wells and springs are in degrees, minutes, and seconds as 

determined from topographic maps based upon site visits, tax parcel maps, and (or) conversations or location maps provided by well owners. Horizontal datum is the North 

American Datum of 1927 (NAD27).

Aquifer: 112ALVM, alluvium; 337HNLM, Huntley Mountain Formation; 341CSKL, Catskill 

Formation; 341LKHV, Lock Haven Formation; 341LNGR, Long Run Member of Catskill Formation; 341TMRK, Trimmers Rock Formation; 341TMSG, Towamensing Member of 

Catskill Formation; 341PGPK, Poplar Gap and Packerton Members of Catskill Formation, 

undivided; 344MNNG, Mahantango Formation.

Depth of well: Depth of drilled well, in feet below land surface, as reported on driller’s log 

or well owner response.

Casing length: Feet of casing used to complete well, as reported on driller’s log or well 

owner response.

Topographic setting: S, slope; H, hilltop; V, valley; W, upland draw.

Reported yield: Gallons per minute, as reported on driller’s log or well owner response.

Year drilled: Year of well construction as reported by driller’s log or well owner.

Sample collector : Owner – well or spring owner; USGS – U.S. Geological Survey.

Total arsenic: Concentration of total arsenic in micrograms per liter.

<, less than

E. coli, Escherichia coli

–, no information 
26 Reconnaissance of Arsenic Concentrations in Ground Water in Eight Northern-Tier Counties of Pennsylvania 

Appendix 2. Records of selected wells and springs, northern-tier counties, Pennsylvania.

USGS

identification

number

Latitude Longitude Aquifer

Depth of well

(feet)

Casing length

(feet) Topography Reported yield

(gal/min)

BRADFORD COUNTY

BR SP-5 414309 764208 341LKHV – – S –

BR-336 414559 763546 341LKHV 151 96 S –

BR-854 415524 764948 341LKHV 255 82 S 20

BR-855 414619 763602 341LKHV 200 143 S –

BR-856 415904 763439 341LKHV 125 30 V –

BR-857 413608 761540 341CSKL 132 32 S –

BR-858 414214 764945 112ALVM 40 40 V –

BR-859 415603 762945 341LKHV 150 20.5 S –

BR-860 415627 763842 341LKHV 167 – S –

BR-861 413942 764749 112ALVM 15 15 V –

BR-862 414756 761054 341LKHV 110 – V –

BR-863 413945 765141 341CSKL 132 – V –

BR-864 414515 762718 341LKHV 158 20 H –

BR-865 414629 764751 341CSKL – – V –

BR-866 413503 762218 341CSKL 95 95 H –

BR-867 415915 761737 341LKHV 140 20.5 H 15

BR-868 414803 764949 341CSKL 400 20 S –

BR-869 415427 765005 341LKHV 130 20 S –

BR-870 415427 765008 341LKHV 130 30 S –

BR-871 415433 763615 341LKHV 150 90 H –

BR-872 415757 763045 112ALVM 245 216 V –

BR-873 413508 762207 341CSKL 90 – V –

BR-874 413504 762809 341CSKL 140 – H –

PIKE COUNTY

PI-523 411709 745207 341LNGR 400 60 S –

PI-524 411849 745339 341TMRK 380 182 V –

PI-525 411235 745434 344MNNG 140 20 S –

PI-526 412218 750345 341LNGR 250 200 S –

PI-527 412456 745426 341LNGR 175 – H –

PI-528 411445 745346 341TMRK 420 380 S –

PI-529 412317 745433 341LNGR 120 40 V –

PI-530 412439 744432 341TMRK 220 38 V –

PI-531 412628 750016 341LNGR 20 – H –

PI-532 412812 750244 341LNGR 230 – V –

PI-533 411330 745624 341TMSG – – S –

PI-534 411738 745601 341LNGR – – S –

PI-535 412526 750046 341LNGR 125 – S –

PI-536 412827 750234 341LNGR – – S –

PI-537 411523 745332 344MNNG 85 20 W –

PI-538 412119 745934 341LNGR – – S –

PI-539 411452 745347 344MNNG 180 180 S –
 27

Appendix 2. Records of selected wells and springs, northern-tier counties, Pennsylvania.—Continued

Driller Year drilled Owner comment

Date sampled 

for total arsenic 

(mo/yr)

Sample

collecter

Remark Total arsenic 

(μg/L)

– – None Apr-06 Owner < 4.0

Cummings 1980 None Apr-06 Owner < 4.0

Havens 1986 None Jun-06 Owner – 117.0

Karp 1992 Hard water, iron, smell Apr-06 Owner – 39.4

Vanderhoof 1968 Iron staining, smell Apr-06 Owner < 4.0

Cummings 1997 Yellow slime Apr-06 Owner < 4.0

– 1970 None May-06 Owner < 4.0

Vanderhoof 1990 Iron staining Apr-06 Owner < 4.0

– 1992 Iron staining Apr-06 Owner < 4.0

– 1890 Hard water Apr-06 Owner < 4.0

– 1998 Iron, smell Apr-06 Owner < 4.0

Troutmen 1966 None Apr-06 Owner < 4.0

Cummings 1972 Smell May-06 Owner < 4.0

Havens 1985 None May-06 Owner < 4.0

Cummings 2004 Brackish Mar-06 Owner < 4.0

Vanderhoof 1991 None Apr-06 Owner < 4.0

– 1998 Cloudy Apr-06 Owner < 4.0

Vanderhoof 1945 None Apr-06 Owner < 4.0

Havens 1963 Smell Apr-06 Owner < 4.0

Vanderhoof 1973 Iron staining Apr-06 Owner < 4.0

Vanderhoof 1985 Gasoline Apr-06 Owner < 4.0

– 1955 Smell Mar-06 Owner – 5.3

Cummings 1995 Staining and E. coli May-06 Owner < 4.0

Greening 1980 None Mar-06 Owner < 4.0

– 2005 Smell Apr-06 Owner < 4.0

Steeler 1983 Smell Mar-06 Owner < 4.0

Greening 1980 Rusty water Mar-06 Owner < 4.0

Weber 1994 Blue stains Mar-06 Owner < 4.0

– 1980 Smell Mar-06 Owner < 4.0

Greening 1971 Iron and manganese Apr-06 Owner < 4.0

Aqua Find Co. 2005 Smell May-06 Owner < 4.0

– 2002 Copper staining Apr-06 Owner < 4.0

Fritz Bros. 1978 Sediment Apr-06 Owner < 4.0

– 1972 Iron staining Apr-06 Owner < 4.0

Weber 2003 None Apr-06 Owner < 4.0

Shields 1945 None Apr-06 Owner < 4.0

Fritz Bros. 1964 Iron staining Apr-06 Owner < 4.0

– 1968 Smell Apr-06 Owner < 4.0

– 1987 Rust Apr-06 Owner < 4.0

– 1976 None Apr-06 Owner < 4.0

Appendix 2 
28 Reconnaissance of Arsenic Concentrations in Ground Water in Eight Northern-Tier Counties of Pennsylvania 

Appendix 2. Records of selected wells and springs, northern-tier counties, Pennsylvania.—Continued

USGS

identification

number

Latitude Longitude Aquifer

Depth of well

(feet)

Casing length

(feet) Topography Reported yield(gal/min)

PI-540 412749 745456 341LNGR 250 230 S –

PI-541 412700 745534 341LNGR – – V –

PI-542 412449 745453 341LNGR – – S –

PI-543 412734 745657 341LNGR 200 – H –

PI-544 411732 745536 341LNGR 300 43 S –

PI-545 411759 751434 341PGPK – – H –

PI-546 412240 745537 341LNGR 150 – W –

PI-547 412739 750654 341LNGR 180 121 S 100

POTTER COUNTY

PO-291 413821 773930 341CSKL 425 16 H 9

PO-292 413533 780338 341CSKL 68 42 V 15

PO-293 414436 780510 341CSKL 60 20 V –

PO-294 414845 775932 341CSKL 140 68 V –

PO-295 415015 780228 341CSKL 300 35 W –

PO-286 415447 773857 341CSKL 300 – W –

PO-287 415909 773839 341LKHV 190 – S –

PO-288 415025 780358 341LKHV 90 – W –

PO-289 414543 780233 341CSKL 100 50 V –

PO-290 414726 781036 341LKHV 120 110 S –

SUSQUEHANNA COUNTY

SQ-449 413942 754706 341CSKL 160 60 S –

SQ-450 414807 753856 341CSKL – – S –

SQ-451 414752 753921 341CSKL – – V –

SQ-452 415720 753728 341CSKL 280 – S –

SULLIVAN COUNTY

SU SP-3 412721 762636 112ALVM – – V –

SU-134 412928 762308 337HNLM 323 41 H –

SU-135 413032 763400 341CSKL 400 30 S –

SU-136 412917 763607 112ALVM 20 20 V –

SU-137 411950 763524 112ALVM 43 43 V –

SU-138 412038 763345 112ALVM 55 55 V –

SU-139 411951 763527 112ALVM 45 45 V –

SU-140 412009 763551 341CSKL 175 20 H –

SU-141 412700 762652 337HNLM – – S –

SU-142 413236 764606 337HNLM 233 93 S –

SU-143 412633 764231 112ALVM 95 95 V –

SU-144 413158 763825 341CSKL 300 21 S –

SU-145 412633 764236 112ALVM 65 65 V –

SU-146 412255 763050 341CSKL 150 10 H –

SU-147 413313 764447 341CSKL 80 – V –

TIOGA COUNTY

TI SP-3 415613 772627 341CSKL – – S –

TI-106 415417 770819 112ALVM 25 25 V –

TI-120 414521 765945 341CSKL 97 – S –
 29

Appendix 2. Records of selected wells and springs, northern-tier counties, Pennsylvania.—Continued

Driller Year drilled Owner comment

Date sampled 

for total arsenic 

(mo/yr)

Sample

collecter

Remark Total arsenic 

(μg/L)

– 1935 Smell Apr-06 Owner < 4.0

– 1986 None Apr-06 Owner < 4.0

– 1986 None Apr-06 Owner < 4.0

– 1975 None Apr-06 Owner < 4.0

Borger 2003 Smell Apr-06 Owner < 4.0

– 1986 None Apr-06 Owner < 4.0

Weber 2002 Iron staining Apr-06 Owner < 4.0

Hook 2000 None Apr-06 Owner < 4.0

Germania 2005 None Apr-06 Owner < 4.0

Coudersport 1987 Iron staining, smell Apr-06 Owner < 4.0

– – None Apr-06 Owner < 4.0

– 1994 None May-06 Owner < 4.0

– – None Apr-06 Owner < 4.0

Germania 1991 Staining Apr-06 Owner < 4.0

– 1985 Taste, cloudy Apr-06 Owner < 4.0

– 1955 None May-06 Owner < 4.0

Kellog 1972 None Apr-06 Owner < 4.0

Pure Water 1978 None Apr-06 Owner < 4.0

Drake 1991 None Apr-06 Owner < 4.0

– – Rust May-06 Owner < 4.0

Drake – None Mar-06 Owner < 4.0

Treblie 2004 Smell Apr-06 Owner < 4.0

– – None Apr-06 Owner < 4.0

House 1999 Sediment Apr-06 Owner < 4.0

– – None Mar-06 Owner – 9.8

– 1950 None Mar-06 Owner < 4.0

– 1960 Gasoline May-06 Owner < 4.0

Turner 1971 None May-06 Owner < 4.0

Turner 1948 None Mar-06 Owner < 4.0

Turner 1990 None Mar-06 Owner < 4.0

– – Smell, discoloration Mar-06 Owner < 4.0

Cummings – None Mar-06 Owner < 4.0

– – Iron staining Mar-06 Owner < 4.0

Hess 1992 White scale Apr-06 Owner < 4.0

– – None Mar-06 Owner < 4.0

Hornburger 1949 None Apr-06 Owner < 4.0

– – None Mar-06 Owner < 4.0

– – Sediment Apr-06 Owner < 4.0

– 1930 Hard water Jun-06 USGS < 4.0

– 2005 Hard water May-06 Owner < 4.0

Appendix 2
30 Reconnaissance of Arsenic Concentrations in Ground Water in Eight Northern-Tier Counties of Pennsylvania 

Appendix 2. Records of selected wells and springs, northern-tier counties, Pennsylvania.—Continued

USGS

identification

number

Latitude Longitude Aquifer

Depth of well

(feet)

Casing length

(feet) Topography Reported yield(gal/min)

TI-122 413933 770301 337HNLM 177 110 V 310

TI-544 413928 770534 337HNLM 300 235 V 200

TI-576 415743 770632 112ALVM 29 29 V –

TI-577 415559 770613 341LKHV 124 106 V –

TI-578 415852 770442 341LKHV 145 – V –

TI-579 415856 770705 341LKHV 187 – V –

TI-580 415734 770629 341LKHV 220 142 V –

TI-667 415854 765637 341LKHV 100 – V –

TI-668 415424 770836 112ALVM 112 109 V –

TI-669 415852 765635 341LKHV 100 – V –

TI-670 414804 771336 341LKHV 160 – S –

TI-671 414518 773329 341CSKL 127 56 V –

TI-672 414221 770508 341CSKL 225 100 S –

TI-673 414309 771245 341CSKL 100 – S –

TI-674 414650 770243 341LKHV 180 180 S –

TI-675 415430 770912 341LKHV – – V –

TI-676 415420 770835 341LKHV – – V –

TI-677 415427 770820 341LKHV 137 90 V –

TI-678 415426 770820 112ALVM 21 21 V –

TI-679 415552 770635 112ALVM 21 21 V –

TI-680 415903 765719 341LKHV – – V –

TI-681 415858 765626 341LKHV 90 – V –

TI-682 415852 765633 341LKHV – – V –

TI-683 415905 765627 341LKHV 100 – V –

TI-684 414720 771041 341LKHV 180 41 S 20

TI-685 415541 770306 341LKHV 160 25 S –

TI-686 415929 770011 341LKHV – – S –

TI-687 415447 770853 341LKHV 160 – S –

TI-688 415000 771711 341CSKL 165 – V –

TI-689 414808 770610 341LKHV 143 12 S –

TI-690 414932 770124 341LKHV 90 90 S –

TI-691 415700 765542 341LKHV – – S –

TI-692 415636 765512 341LKHV 265 12 H –

TI-693 415550 771615 341LKHV 47 47 W –

TI-694 414926 770419 341LKHV 320 11 H –

TI-695 414548 765944 341LKHV 251 32 S 8.5

TI-696 415738 772644 341LKHV 145 – V –

TI-697 414703 771003 341LKHV 140 20 S –

TI-698 415927 771415 341LKHV 220 120 S –

TI-699 415736 771300 341LKHV 120 40 H –

TI-700 414240 771124 341CSKL – – V –

TI-701 415306 772845 341LKHV 359 50 H –

TI-702 414356 772359 341CSKL 140 30 H –

TI-703 414503 771212 341LKHV 225 – H –
 31

Appendix 2. Records of selected wells and springs, northern-tier counties, Pennsylvania.—Continued

Driller Year drilled Owner comment

Date sampled 

for total arsenic 

(mo/yr)

Sample

collecter

Remark Total arsenic 

(μg/L)

Layne 1960 Iron and manganese Apr-06 Owner < 4.0

Eichleberger 1988 Smell, salty Apr-06 Owner < 4.0

– – None Jul-05 USGS – 47.6

– – None Jul-05 USGS < 4.0

– – None Jul-05 USGS < 4.0

– – None Jul-05 USGS < 4.0

– – None Jul-05 USGS < 4.0

– – None Jun-06 USGS – 16.0

– 1951 None May-06 Owner – 14.4

– – None Jun-06 USGS – 53.8

– 1971 Iron staining May-06 Owner – 34.4

Germania 1950 Iron staining, smell, taste Jun-06 Owner < 4.0

Hess 1998 None Apr-06 Owner < 4.0

– 1897 None May-06 Owner < 4.0

Cizek 1972 Smell, hard water May-06 Owner < 4.0

– 1990 None Jun-06 USGS < 4.0

– 1970 Hard water Jun-06 USGS – 5.1

Andrews 1970 None Jun-06 USGS – 6.9

Hughes 1959 None Jun-06 USGS < 4.0

Owner 1975 None Jun-06 USGS < 4.0

Bellows 2004 Iron staining, smell Jun-06 Owner < 4.0

Hess 1999 Iron staining, smell May-06 Owner – 15.4

– 1976 Iron staining, smell May-06 Owner – 9.0

– 1968 Smell May-06 Owner – 13.0

– 2001 None Apr-06 Owner < 4.0

– 1998 Iron staining, smell, hard water May-06 Owner < 4.0

– 1972 None May-06 Owner < 4.0

– 1963 None Apr-06 Owner < 4.0

– 1970 Iron staining Apr-06 Owner < 4.0

Andrews 1993 Color Apr-06 Owner < 4.0

– 1958 Smell, mineral deposits May-06 Owner < 4.0

Roger 1988 Smell May-06 Owner < 4.0

Bellows 1998 None May-06 Owner < 4.0

Andrews – None Apr-06 Owner < 4.0

Andrews 1997 None May-06 Owner < 4.0

Germania 1995 None May-06 Owner < 4.0

Germania 1963 Staining May-06 Owner – 4.5

Andrews 1982 None May-06 Owner < 4.0

Terwilliger 1981 None May-06 Owner < 4.0

Andrews 1985 Hard water May-06 Owner < 4.0

– 1998 Iron staining May-06 Owner < 4.0

Germania 1974 None May-06 Owner < 4.0

Cizek 1980 Iron May-06 Owner < 4.0

Andrews 1975 None May-06 Owner < 4.0

Appendix 2
32 Reconnaissance of Arsenic Concentrations in Ground Water in Eight Northern-Tier Counties of Pennsylvania 

Appendix 2. Records of selected wells and springs, northern-tier counties, Pennsylvania.—Continued

USGS

identification

number

Latitude Longitude Aquifer

Depth of well

(feet)

Casing length

(feet) Topography Reported yield(gal/min)

TI-704 414624 765430 341CSKL 130 19 S –

TI-705 414339 771922 341LKHV 78 – W –

TI-706 413958 771931 341CSKL – – H –

TI-707 415128 771420 341CSKL – – V –

TI-708 415056 765724 341LKHV – – S –

TI-709 415545 771916 341LKHV 165 35 S –

TI-710 414915 770100 341LKHV 300 32 S 10

TI-711 415545 772124 341LKHV 334 56 S –

TI-713 415139 765725 112ALVM 30 30 V –

TI-714 415738 765626 341LKHV – – W –

TI-715 415911 765615 341LKHV – – S –

TI-716 414448 772018 341CSKL – – S –

TI-717 415632 773447 341LKHV 90 30 V –

TI-718 415909 765627 341LKHV 29 – S –

TI-719 415824 770113 341LKHV 86 40 V –

TI-720 415825 770114 341LKHV 106 40 S –

TI-721 415742 772307 341LKHV 175 – V –

TI-722 415051 772807 341CSKL 317 21 H –

TI-723 414545 771952 341CSKL 300 – H –

WAYNE COUNTY

WN-210 413759 750700 341CSKL 340 50 S –

WN-211 413841 750504 341CSKL 183 42 H –

WN-212 414656 751757 341CSKL 210 90 S –

WN-213 412849 752419 341PGPK 80 – S –

WN-214 413946 751939 341CSKL 356 40 S –

WN-215 413107 751649 341LNGR 132 – S –

WN-216 413412 750623 341LNGR – – W –

WN-217 414136 751316 341CSKL – – S –

WN-218 412246 752057 112ALVM 12 12 S –

WN-219 414726 751512 341CSKL 130 – H –

WN-220 413611 752304 341CSKL 210 40 W –

WN-221 412928 751021 341LNGR 280 41 S –

WN-222 413758 750709 341CSKL – – S –

WN-223 412945 752654 341PGPK 200 – S –

WN-224 413752 750706 341CSKL 160 – S –

WYOMING COUNTY

WY-181 412951 755341 341CSKL 200 40 S –

WY-182 413659 754457 341CSKL 540 – S –

WY-183 413315 761210 341CSKL 250 – S –

WY-184 412956 760754 341CSKL 160 70 V –

WY-185 413114 760750 341CSKL 198 80 V –

WY-186 413029 755000 341CSKL 200 83 S –

WY-187 412743 755125 341CSKL 180 80 V –

WY-188 412545 755118 341CSKL 450 80 H –
 33

Appendix 2. Records of selected wells and springs, northern-tier counties, Pennsylvania.—Continued

Driller Year drilled Owner comment

Date sampled 

for total arsenic 

(mo/yr)

Sample

collecter

Remark Total arsenic 

(μg/L)

Andrews 1989 None Apr-06 Owner – 4.0

Andrews 1978 None May-06 Owner < 4.0

– 1983 None May-06 Owner < 4.0

– 1950 Hard water May-06 Owner < 4.0

– 990 Smell May-06 Owner < 4.0

Andrews 2001 Wormy smell Apr-06 Owner < 4.0

Burgess 1996 None Apr-06 Owner < 4.0

Germania 2002 Iron staining Apr-06 Owner < 4.0

– 1976 None Apr-06 Owner < 4.0

Hess 1995 Iron and manganese Apr-06 Owner < 4.0

– 1986 Iron staining Apr-06 Owner < 4.0

– 1950 None Apr-06 Owner < 4.0

McLaughlin 1948 Iron staining, smell Apr-06 Owner < 4.0

– 1957 Iron staining, smell Apr-06 Owner < 4.0

Darmstadt 1993 Iron staining, smell May-06 Owner < 4.0

– 1984 Rusty water May-06 Owner < 4.0

McLaughlin 1975 Iron staining Apr-06 Owner – 9.8

Germania 1997 Sediment Apr-06 Owner < 4.0

Hess 1992 None May-06 Owner < 4.0

Davis 1979 Iron Mar-06 Owner – 188.0

Smith 1974 None May-06 Owner < 4.0

Tully 1994 Iron staining, smell Mar-06 Owner < 4.0

Fritz Bros. 1974 None Apr-06 Owner < 4.0

Fritz Bros. – None Mar-06 Owner < 4.0

Fritz Bros. 1998 Iron staining Apr-06 Owner < 4.0

– 1950 None Apr-06 Owner < 4.0

– – None Mar-06 Owner < 4.0

Owner 1964 Corrosion Apr-06 Owner < 4.0

Fritz Bros. 1993 None Apr-06 Owner < 4.0

Fritz Bros. 1974 None Mar-06 Owner < 4.0

Hook 2004 None Mar-06 Owner < 4.0

– – None Jun-06 USGS < 4.0

– – Taste Mar-06 Owner < 4.0

– – None Jun-06 USGS < 4.0

Cress 1960 Iron staining, taste Mar-06 Owner < 4.0

Cress 1977 None Apr-06 Owner < 4.0

Strumski 1987 Iron staining Mar-06 Owner < 4.0

– 1985 Iron Apr-06 Owner < 4.0

Cress 1974 None May-06 Owner < 4.0

Cress 1971 None May-06 Owner < 4.0

– 1945 None May-06 Owner < 4.0

Leib 1995 None Apr-06 Owner < 4.0

Appendix 2
34 Reconnaissance of Arsenic Concentrations in Ground Water in Eight Northern-Tier Counties of Pennsylvania 

Appendix 2. Records of selected wells and springs, northern-tier counties, Pennsylvania.—Continued

USGS

identification

number

Latitude Longitude Aquifer

Depth of well

(feet)

Casing length

(feet) Topography Reported yield(gal/min)

WY-189 412819 760852 341CSKL 75 60 V –

WY-190 412615 755626 341CSKL 100 100 S –

WY-191 413038 755758 341CSKL – – W –
 35

Appendix 2. Records of selected wells and springs, northern-tier counties, Pennsylvania.—Continued

Driller Year drilled Owner comment

Date sampled 

for total arsenic 

(mo/yr)

Sample

collecter

Remark Total arsenic 

(μg/L)

Jimcon 2005 Iron Apr-06 Owner < 4.0

– 1988 None May-06 Owner < 4.0

– 1990 None Apr-06 Owner < 4.0

Appendix 2