Prepared in cooperation with the 

Pennsylvania Department of Conservation and Natural Resources, 

Bureau of Topographic and Geologic Survey

Baseline Groundwater Quality from 20 Domestic Wells 

in Sullivan County, Pennsylvania, 2012

Scientific Investigations Report 2013–5085

U.S. Department of the Interior

U.S. Geological Survey
Cover. North Mountain, Laporte Township, Sullivan County, Pennsylvania. View is looking southeast from “Wright’s View” across 

the Muncy Creek Valley.
Baseline Groundwater Quality from 

20 Domestic Wells in Sullivan County, 

Pennsylvania, 2012

By Ronald A. Sloto

Prepared in cooperation with the 

Pennsylvania Department of Conservation and Natural Resources, 

Bureau of Topographic and Geologic Survey

Scientific Investigations Report 2013–5085

U.S. Department of the Interior

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

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2013

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as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:

Sloto, R.A., 2013, Baseline groundwater quality from 20 domestic wells in Sullivan County, Pennsylvania, 2012: 

U.S. Geological Survey Scientific Investigations Report 2013–5085, 27 p., http://pubs.usgs.gov/sir/2013/5085/
iii

Acknowledgements

The cooperation of the residents of Sullivan County who made their wells accessible for 

sampling is greatly appreciated. The author thanks Taylor Suskie of the Pennsylvania Geological Survey for her assistance with well location and sampling.

Contents

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

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

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

Description of Study Area ...................................................................................................................3

Population and Land Use............................................................................................................3

Physiography and Geologic Setting .........................................................................................3

Alluvium................................................................................................................................3

Allegheny and Pottsville Formations ...............................................................................3

Mauch Chunk Formation ...................................................................................................3

Burgoon Sandstone............................................................................................................5

Huntley Mountain Formation ............................................................................................5

Catskill Formation ...............................................................................................................5

Lock Haven Formation .......................................................................................................5

Methods...........................................................................................................................................................6

Site Selection.........................................................................................................................................6

Sampling and Analytical Methods.....................................................................................................6

Baseline Groundwater Quality.....................................................................................................................8

Physical Properties...............................................................................................................................8

Major Ions............................................................................................................................................12

Nutrients...............................................................................................................................................12

Metals and Trace Elements...............................................................................................................12

Radionuclides......................................................................................................................................12

Dissolved Gases..................................................................................................................................13

Summary........................................................................................................................................................25

References Cited..........................................................................................................................................26
iv

Figures

1. Land use and State lands in Sullivan County, Pennsylvania .................................................2

2. Geology and location of groundwater-sampling sites, Sullivan County, 

Pennsylvania .................................................................................................................................4

3. Stratigraphic chart for Sullivan County, Pennsylvania. From Edmunds (1996)...................5

4. Relation between total dissolved solids and specific conductance for groundwater

samples from wells in Sullivan County, Pennsylvania............................................................8

5. Stable isotopic composition of carbon and hydrogen in dissolved methane 

in two groundwater samples from Sullivan County, Pennsylvania ....................................24

Tables

1. Information on 20 wells sampled in Sullivan County, Pennsylvania, 2012 ..........................7

2. Summary statistics for physical properties and dissolved gas concentrations 

in water samples from 20 wells sampled in Sullivan County, Pennsylvania, 2012.............9

3. Physical properties and dissolved gas concentrations for water samples 

from 20 wells, Sullivan County, Pennsylvania, 2012..............................................................10

4. U.S. Environmental Protection Agency maximum contaminant, secondary

contaminant, and action levels for constituents in drinking water....................................11

5. Summary statistics for concentrations of major ions in water samples 

from 20 wells, Sullivan County, Pennsylvania, 2012..............................................................14

6. Concentrations of major ions in water samples from 20 wells, Sullivan County,

Pennsylvania, 2012 .....................................................................................................................15

7. Summary statistics for concentrations of nutrients in water samples 

from 20 wells, Sullivan County, Pennsylvania, 2012..............................................................16

8. Concentrations of nutrients in water samples from 20 wells, Sullivan County,

Pennsylvania, 2012 .....................................................................................................................17

9. Summary statistics for concentrations of metals and trace elements in samples

from 20 wells, Sullivan County, Pennsylvania, 2012. ............................................................18

10. Concentrations of metals and trace elements in samples from 20 wells, 

Sullivan County, Pennsylvania, 2012........................................................................................20

11. Summary statistics for concentrations and activities of radioactive constituents 

in samples from 20 wells, Sullivan County, Pennsylvania, 2012..........................................22

12. Concentrations and activities of radioactive constituents in samples 

from 20 wells, Sullivan County, Pennsylvania, 2012..............................................................23
v

Conversion Factors

Inch/Pound to SI

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)

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).

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

Abbreviations

AMCL alternate maximum contaminant levels

MCL maximum contaminant level

PaGS Pennsylvania Geological Survey

SMCL secondary maximum contaminant level

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

μg/L micrograms per liter

mg/L milligrams per liter

μS/cm microsiemens per centimeter at 25 degrees Celsius

pCi/L picocuries per liter
vi

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Baseline Groundwater Quality from 20 Domestic Wells in 

Sullivan County, Pennsylvania, 2012

By Ronald A. Sloto

Abstract

Water samples were collected from 20 domestic wells 

during August and September 2012 and analyzed for 47 constituents and properties, including nutrients, major ions, metals 

and trace elements, radioactivity, and dissolved gases, including methane and radon-222. This study, done in cooperation 

with the Pennsylvania Department of Conservation and Natural Resources, Bureau of Topographic and Geologic Survey 

(Pennsylvania Geological Survey), provides a groundwaterquality baseline for central and southern Sullivan County prior 

to drilling for natural gas in the Marcellus Shale. 

The analytical results for the 20 groundwater samples 

collected during this study indicate that only one constituent 

(gross-alpha radioactivity) in one sample was found to exceed 

the U.S. Environmental Protection Agency (USEPA) primary 

drinking water maximum contaminant level (MCL). Water 

samples from 85 percent of the sampled wells exceeded the 

proposed USEPA MCL of 300 picocuries per liter (pCi/L) 

for radon-222; however, only two water samples (10 percent 

of sampled wells) exceeded the proposed USEPA alternate 

maximum contaminant level (AMCL) of 4,000 pCi/L for 

radon-222. In a few samples, the concentrations of total dissolved solids, iron, manganese, and chloride exceeded USEPA 

secondary maximum contaminant levels (SMCL). In addition, 

water samples from two wells contained methane concentrations greater than 1 milligram per liter (mg/L). 

In general, most of the water-quality problems involve 

aesthetic considerations, such as taste or odor from elevated 

concentrations of total dissolved solids, iron, manganese, and 

chloride that develop from natural interactions of water and 

rock minerals in the subsurface. The total dissolved solids 

concentration ranged from 31 to 664 mg/L; the median was 

130 mg/L. The total dissolved solids concentration in one 

water sample exceeded the USEPA SMCL of 500 mg/L. 

Chloride concentrations ranged from 0.59 to 342 mg/L; the 

median was 12.9 mg/L. The concentration of chloride in 

one water sample exceeded the USEPA SMCL of 250 mg/L. 

Concentrations of dissolved iron ranged from less than 3.2 to 

6,590 micrograms per liter (μg/L); the median was 11.5 μg/L. 

The iron concentration in samples from 20 percent of the 

sampled wells exceeded the USEPA SMCL of 300 μg/L. 

Concentrations of dissolved manganese ranged from less than 

0.13 to 1,710 μg/L; the median was 38.5 μg/L. The manganese 

concentration in samples from 35 percent of the sampled wells 

exceeded the USEPA SMCL of 50 μg/L. 

Activities of radon-222 ranged from 169 to 15,300 picocuries per liter (pCi/L); the median was 990 pCi/L. The gross 

alpha-particle radioactivity ranged from below detection to 

33 pCi/L; the median was 1.5 pCi/L. The gross alpha-particle 

radioactivity of one water sample exceeded the USEPA MCL 

of 15 pCi/L. 

Concentrations of dissolved methane ranged from less 

than 0.001 to 51.1 mg/L. Methane was not detected in water 

samples from 13 wells, and the methane concentration was 

less than 0.07 mg/L in samples from five wells. The highest 

dissolved methane concentrations were 4.1 and 51.1 mg/L, 

and the pH of the water from both wells was greater than 8. 

Water samples from these wells were analyzed for isotopes of 

carbon and hydrogen in the methane. The isotopic ratio values 

fell in the range for a thermogenic (natural gas) source. The 

water samples from these two wells had the highest concentrations of arsenic, boron, bromide, chloride, fluoride, lithium, 

molybdenum, and sodium of the 20 wells sampled.

Introduction

Sullivan County, which is located in north central Pennsylvania (fig. 1), is underlain by the Marcellus Shale. The 

Marcellus Shale, which is being exploited for natural gas, 

lies approximately 6,000 to 9,000 feet (ft) below land surface 

in Sullivan County. All of the residents of Sullivan County 

rely on groundwater as a source of water supply. Drilling 

and hydraulic fracturing of horizontal natural gas wells have 

the potential to contaminate freshwater aquifers that provide 

drinking water and the base flow of streams (Kargbo and others, 2010; Kerr, 2010; U.S. Environmental Protection Agency, 

2013a). Since 2006, permits have been issued for 188 Marcellus Shale gas wells (Pennsylvania Department of Environmental Protection, 2012a), and 67 natural gas wells have been 

drilled into the Marcellus Shale in Sullivan County. Most of 
2 Baseline Groundwater Quality from 20 Domestic Wells in Sullivan County, Pennsylvania, 2012

76°40' 76°30' 76°20'

41°

30'

41°

20'

EXPLANATION

State lands

State park

Pennsylvania Bureau of Forestry

State gameland

State forest

Land use

Agricultural

Developed

Forested

Open water

0 4 8 MILES

0 4 8 KILOMETERS

Sullivan County

Marcellus Shale

EXPLANATION

State park boundaries from Pennsylvania Department of Conservation and Natural 

Resources (2011); State forest boundaries from Pennsylvania Department of Conservation 

and Natural Resources (2010); State gamelands boundaries from Pennsylvania Game 

Commission (2011); County boundary and roads from Pennsylvania Department of 

Transportation (2009a, 2009b); land use from LaMotte (2008) 

Base from U.S. Geological Survey digital data

220

220

154

87

42

87

487

220

WORLDS END

STATE PARK

Pennsylvania 

Bureau of

Forestry

DUSHORE

WYOMING

STATE FOREST

FORKSVILLE

LAPORTE

SULLIVAN COUNTY

LYCOMING

COUNTY

BRADFORD

COUNTY

LUZERNE

COUNTY

COLUMBIA

 COUNTY

WYOMING

 COUNTY

RICKETTS GLEN

STATE PARK

WYOMING

STATE FOREST

Gamelands

66

Gamelands

13

Gamelands

134

Gamelands

12

Figure 1. Land use and State lands in Sullivan County, Pennsylvania.
Introduction 3

the wells are in the northern part of the county (Pennsylvania 

Department of Environmental Protection, 2012b). 

Pre-gas well drilling groundwater-quality data for watersupply wells in the northern part of Sullivan County have 

been collected by the natural-gas industry. However, data are 

not available for most of the central and southern part of the 

county. Without baseline data for associated water-quality constituents, it is not possible to establish a connection between 

gas production activities and the well-water chemistry that 

might be affected. This study, conducted by the U.S. Geological Survey (USGS) in cooperation with the Pennsylvania 

Department of Conservation and Natural Resources, Bureau of 

Topographic and Geologic Survey (Pennsylvania Geological 

Survey), provides a pre-gas well drilling groundwater-quality 

baseline for the central and southern part of Sullivan County.

Purpose and Scope

This report presents analytical data for water samples 

from 20 domestic wells sampled in central and southern Sullivan County in August and September 2012. The water samples 

were analyzed for 47 constituents, including nutrients, major 

ions, metals and trace elements, radioactivity, and dissolved 

gases, including methane and radon-222. The groundwaterquality data and summary statistics are presented for sampled 

constituents to provide a pre-gas well drilling baseline.

Description of Study Area

Sullivan County occupies 450 square miles (mi2) in 

north central Pennsylvania (fig. 1). Land-surface elevations are highest (more than 2,500 ft above NAVD 88) in the 

mountains of the southeastern part of the county and lowest 

in the southwestern part of the county (as low as about 755 ft 

above NAVD 88) (U.S. Geological Survey, 2009). Average 

annual temperatures in Sullivan County range from about 44 

to 49 degrees Fahrenheit with the warmest average annual 

temperatures occurring in the southwestern part of the county 

and the coldest average annual temperatures occurring in the 

mountainous areas in the northwestern, northeastern, and 

southeastern parts of the county (PRISM Group at Oregon 

State University, 2013). Average annual precipitation varies from west to east with an average of 40 inches in the 

western part of the county and an average of 54 inches in the 

eastern part of the county (PRISM Group at Oregon State 

University, 2013).

Population and Land Use

Sullivan County is rural with a population of 6,496 in 

2010 (U.S. Census Bureau, 2013). The 2010 population is 

less than double the population in 1850 (Sullivan County 

Planning and Economic Development Office, 2010). Areas 

most densely populated are the boroughs of Dushore, Forksville, and Laporte (fig. 1) with 2010 populations of 746, 63, 

and 313, respectively. Seasonal dwellings made up 56 percent of housing units in the county in 2010 (U.S. Census 

Bureau, 2013).

About 87 percent of the county is forested with approximately 38 percent of forested land consisting of state parks, 

forests, and gamelands (fig. 1) (LaMotte, 2008). Agricultural 

lands are typically found in the narrow valley bottoms in the 

northern and south-central part of the county. Approximately 

10 percent of the county is devoted to agriculture with about 

5 percent of the county in cropland (Sullivan County Planning 

and Economic Development Office, 2010). About 3 percent of 

the county consists of developed land.

Physiography and Geologic Setting

Sullivan County is mostly located in the Appalachian 

Plateaus Physiographic Province (Sevon, 2000). The northern 

part of the county is in the Glaciated Low Plateau Section. This 

study was conducted in the central and southern parts, which 

are divided between the western Deep Valleys Section, and 

the eastern Glaciated High Plateaus Section. The Deep Valleys 

Section is characterized by very deep, angular valleys with 

some broad to narrow uplands. The Glaciated High Plateaus 

Section is characterized by broad to narrow, rounded to flat, 

elongate uplands and shallow valleys.

Sullivan County is underlain by bedrock of Pennsylvania, Mississippian, and Devonian age (figs. 2 and 3). Alluvium overlies the bedrock in the stream valleys. The geologic 

descriptions below for alluvium and bedrock units cropping 

out in Sullivan County are from Taylor and others (1983).

Alluvium

The thick, unconsolidated deposits of Quaternary age that 

fill the stream valleys are collectively called alluvium. Alluvium, which consists of gravel, sand, and clay, fills some valleys to depths of over 200 ft. In some areas, the alluvium has 

been transported relatively long distances as a result of glacial 

processes (outwash), and in other areas, it has been weathered 

from the nearby rock formations.

Allegheny and Pottsville Formations

In Sullivan County, the rocks of Pennsylvanian age are 

mapped as the Allegheny and Pottsville Formations, undivided. 

The Allegheny Formation is composed of sandstone, siltstone, 

thin beds of limestone, and coal. Reported thicknesses for this 

unit are consistently about 300 ft. The upper part of the Pottsville Formation consists mainly of sandstone, siltstone, thin 

beds of coal, and conglomerate. The lower part of the Pottsville 

Formation consists predominantly of sandstone. Thickness 

estimates for the Pottsville Formation range from 140 to 200 ft.

Mauch Chunk Formation

The Mauch Chunk Formation of Mississippian age 

generally consists of two units. The lower unit is interbedded 
4 Baseline Groundwater Quality from 20 Domestic Wells in Sullivan County, Pennsylvania, 2012

Geology from Miles and Whitfield (2001) 

SU-167

SU-166

SU-165

SU-164

SU-163

SU-162

SU-161

SU-159

SU-157

SU-155

SU-154

SU-153

SU-152

SU-151

SU-150

SU-149

SU-148

SU-158

SU-160

SU-156

76°40' 76°30' 76°20'

41°

30'

41°

20'

0 4 8 MILES

0 4 8 KILOMETERS

Base from U.S. Geological Survey digital data

LYCOMING

COUNTY

BRADFORD

COUNTY

LUZERNE

COUNTY

COLUMBIA

 COUNTY

WYOMING

 COUNTY

Geology

Allegheny and Pottsville Formations, undivided

Pottsville Formation

Mauch Chunk Formation

Burgoon Sandstone of the Pocono Formation

Huntley Mountain Formation

Catskill Formation

Lock Haven Formation

SU-150 Sampled well and 

identification number

EXPLANATION

SULLIVAN COUNTY

Figure 2. Geology and location of groundwater-sampling sites, Sullivan County, Pennsylvania.
Introduction 5

SYSTEM

Pennsylvanian

Quaternary

Allegheny Formation

alluvium

GEOLOGIC UNIT LITHOLOGY

Mauch Chunk Formation

Pottsville Formation

Burgoon Sandstone Member

Mississippian

Catskill Formation

Huntley Mountain Formation

Devonian

Poorly sorted clay, sand,

and gravel

Sandstone, siltstone, 

limestone, and coal

Lock Haven Formation

Allegheny and Pottsville

Formations, undivided

Pocono

Formation

Sandstone, siltstone, 

coal, and conglomerate

Sandstone, siltstone, shale,

and mudstone

Sandstone, shale,

conglomerate, and 

mudstone

Sandstone, siltstone, and

shale

Sandstone, siltstone, shale,

and conglomerate

Sandstone, siltstone, shale,

and conglomerate

Figure 3. Stratigraphic chart for Sullivan County, Pennsylvania. From Edmunds (1996).

sandstone, siltstone, shale, and mudstone. The upper unit is 

a light-gray calcareous quartz sandstone. The Mauch Chunk 

Formation is up to 300 ft thick.

Burgoon Sandstone

The Mississippian age Burgoon Sandstone Member of 

the Pocono Formation is informally divided into two units. 

The upper unit consists of light-gray, fine- to medium-grained, 

well-sorted, pure quartz sandstone (orthoquartzite). The lower 

unit consists of gray sandstone and minor interbedded gray 

shale, conglomerate, and mudstone. Reported thicknesses for 

the upper member range from 120 to 240 ft. Reported thicknesses for the lower member range from 570 to 800 ft.

Huntley Mountain Formation

The Huntley Mountain Formation of Late Devonian 

and Early Mississippian age consists of greenish-gray to 

light olive-gray sandstone and some thin beds of grayish-red 

siltstone or clay shale. The formation is reported to be about 

600 ft thick.

Catskill Formation

The Catskill Formation of Devonian age consists of a 

succession of grayish-red sandstone, siltstone, and shale with 

some gray sandstone and conglomerate. The sandstone layers 

are generally fine grained and thin bedded. The thickness of 

the Catskill Formation varies from about 1,200 to 2,000 ft.

Lock Haven Formation

The Lock Haven Formation of Devonian age is composed 

predominantly of light olive gray interbedded sandstone, 

siltstone, shale, and a few thin beds of conglomerate near 

the top. No wells completed in the Lock Haven Formation 

were sampled.
6 Baseline Groundwater Quality from 20 Domestic Wells in Sullivan County, Pennsylvania, 2012

Methods

Water samples were collected from 20 domestic wells 

(table 1 and fig. 2) during August and September 2012 and 

analyzed to characterize their physical and chemical quality. Samples were analyzed for 47 constituents and properties, including nutrients, major ions, metals and trace elements, radioactivity, and dissolved gases, including methane 

and radon-222. Two samples, one field blank and one 

replicate sample, were collected for quality assurance and 

quality control.

Site Selection

Selection of water wells for sampling was made by the 

USGS in consultation with the Pennsylvania Geological 

Survey (PaGS). Wells were selected from the Pennsylvania 

Groundwater Information System database (Pennsylvania 

Geological Survey, 2012). Only wells with construction data 

on file were considered. A field reconnaissance was conducted 

to locate 20 wells, obtain permission to sample, and verify that 

any treatment systems could be bypassed. All wells selected 

for sampling are private domestic wells (table 1).

Sampling and Analytical Methods

The USGS and PaGS sampled the wells by using standard USGS field-sampling protocols. Samples were collected 

at an untreated tap, typically at a pressure tank and before any 

filtration, water softening, or bacteriological treatment. Water 

samples were analyzed in the field for physical properties and 

dissolved oxygen and shipped overnight to laboratories for 

analysis for major ions, nutrients, metals and trace elements, 

gross alpha and beta radioactivity, and dissolved gases. The 

samples were collected from each well and processed for 

analysis by methods described in USGS manuals for the collection of water-quality data (U.S. Geological Survey, variously dated).

Sampling was done at all well sites using the following 

steps. (1) The existing submersible well pump was turned on 

and allowed to run. (2) A raw-water tap between the well and 

the pressure tank was opened, and the water was allowed to 

flush to ensure that the water was representative of the aquifer. 

(3) The water was analyzed with a multiprobe meter for physical properties (temperature, specific conductance, and pH) and 

dissolved oxygen concentration. (4) After the measurements of 

these physical properties stabilized, pre-rinsed sample bottles 

were filled according to USGS protocols (U.S. Geological Survey, variously dated). Samples were collected through a short 

piece of silicone tubing attached to the raw-water tap, which 

avoided all water-treatment systems. 

The analyses for physical properties, radioactivity, and 

dissolved gases were done on unfiltered water samples to 

obtain total concentrations. Samples for dissolved concentrations of nutrients, major ions, and metals and trace elements 

were filtered through a pre-rinsed 0.45-micrometer cellulose 

capsule filter. To prevent sample degradation, nitric acid was 

added to the major ion and metals and trace-element samples. 

Samples for radon analysis were obtained through an inline 

septum with a gas-tight syringe to avoid atmospheric contact. 

Samples for gross alpha and beta radioactivity and dissolved 

gases were obtained through silicon tubing that was placed in 

bottles that were filled and stoppered while submerged in a 

5-liter beaker of pumped water to avoid atmospheric contact.

The samples were stored on ice in coolers and shipped 

by overnight delivery to the following three laboratories: 

(1) the USGS National Water Quality Laboratory in Denver, 

Colorado, for analysis of major ions, nutrients, metals and 

trace elements, and radon; (2) a USGS contract laboratory in 

California for analysis of gross alpha and beta radioactivity; 

and (3) the USGS Chlorofluorocarbon Laboratory in Reston, 

Virginia, for analysis of methane and other dissolved gases. 

Descriptions of analytical methods for all constituents except 

the dissolved gases and isotopes are available through the 

U.S. Geological Survey (2012a); the methods for determination of dissolved gases in water are described by the U.S. 

Geological Survey (2012b). The analytical results are available through the USGS National Water Information System 

(U.S. Geological Survey, 2012c).

Water samples containing methane concentrations 

greater than 1 milligram per liter (mg/L) were shipped on 

ice to a contract laboratory in Illinois for hydrocarbon and 

isotopic analysis. The stable carbon isotopes 12C and 13C and 

the stable hydrogen isotopes 1H (protium) and 2H (deuterium) 

were determined. For the determination of carbon and hydrogen isotopic ratios for hydrocarbons in a gas mixture, individual hydrocarbons were first separated and then converted 

into carbon dioxide and water for mass-spectrometric analysis. The hydrocarbons were separated from the water sample 

by using a gas chromatograph and channeled into a combined 

combustion-collection unit. The combined combustion-collection unit has quartz combustion tubes filled with cupric oxide 

to convert the hydrocarbons into carbon dioxide and water, 

which are then collected and purified for isotopic analysis. 

The carbon dioxide was transferred into Pyrex tubing and sealed for mass spectrometric analysis. The 13C/12C 

ratio was determined by a mass spectrometric analysis that 

compared the sample to a reference standard. The carbon 

isotope ratio value (δ13C) is reported in terms of per mil (‰) 

notation with respect to the Vienna Peedee Belemnite (VPDB) 

standard. Water samples for hydrogen isotope analysis were 

sealed into Pyrex tubing along with a measured quantity of 

zinc. Each sample tube was reacted in a heating block at 

500°C for 35 minutes to generate hydrogen gas. Once the 

sample had been reacted, the 1H/2H ratio was determined by 

mass spectrometric analysis that compared the sample to a 

reference standard. The hydrogen isotope ratio value (δD) 

is reported in terms of per mil notation with respect to the 

Vienna Standard Mean Ocean Water (VSMOW) standard 

(Alan R. Langenfeld, Isotech Laboratories, Inc., written commun., 2012).
Methods 7

Table 1. Information on 20 wells sampled in Sullivan County, Pennsylvania, 2012.

[Well locations are shown in figure 2. --, information not available; >, greater than; R, reported]

Wellidentification 

number

Date

sampled

Well depth

(feet below 

land surface)

Casing 

length 

(feet)

Yield

(gallons 

per minute)

Depth to 

water

(feet below 

land surface)

Geologic unit

SU-148 8/22/2012 245 20 15 -- Mauch Chunk Formation

SU-149 8/20/2012 250 50 30 >140 Burgoon Sandstone member of the Pocono Formation

SU-150 8/14/2012 440 40 10 -- Burgoon Sandstone member of the Pocono Formation

SU-151 8/15/2012 340 41 10 -- Catskill Formation

SU-152 8/15/2012 115 40 23 -- Huntley Mountain Formation

SU-153 8/15/2012 250 67 9 -- Huntley Mountain Formation

SU-154 8/14/2012 248 129 15 -- Huntley Mountain Formation

SU-155 8/23/2012 145 81 5 -- Mauch Chunk Formation

SU-156 8/16/2012 250 30 2 100 R Catskill Formation

SU-157 8/21/2012 280 268 10 114.1 Huntley Mountain Formation

SU-158 8/22/2012 46 12 6 15 R Huntley Mountain Formation

SU-159 8/23/2012 104 104 20 30 R Alluvium

SU-160 8/15/2012 500 40 1.5 235.4 Catskill Formation

SU-161 9/5/2012 200 50 15 50 R Burgoon Sandstone member of the Pocono Formation

SU-162 8/21/2012 140 60 >25 -- Huntley Mountain Formation

SU-163 8/21/2012 100 54 15 -- Burgoon Sandstone member of the Pocono Formation

SU-164 8/22/2012 300 40 30 -- Allegheny and Pottsville Formations, undivided

SU-165 8/20/2012 440 60 6 -- Catskill Formation

SU-166 8/23/2012 180 30 4 80 R Mauch Chunk Formation

SU-167 8/27/2012 200 40 10 -- Mauch Chunk Formation
8 Baseline Groundwater Quality from 20 Domestic Wells in Sullivan County, Pennsylvania, 2012

Baseline Groundwater Quality

Analytical results for the 20 groundwater samples collected during this study are provided in the following sections. 

The quality of the sampled groundwater was generally within 

U.S. Environmental Protection Agency (USEPA) standards, 

although in some samples, the concentrations of certain 

constituents exceeded drinking-water standards (U.S. Environmental Protection Agency, 2006, 2012). In general, most of the 

water-quality problems involve aesthetic considerations, such 

as taste or odor from excessive dissolved solids, iron, manganese, and chloride that develop from natural interactions of 

water and rock minerals in the subsurface.

The quality assurance/quality control (QA/QC) fieldblank sample contained no constituent in concentrations 

greater than the laboratory reporting levels; this indicates 

that no contamination occurred through the sampling or 

analytical procedures.

The difference in concentration between the sample 

and the QA/QC replicate sample (well SU-162) ranged from 

0 to 2.5 percent for major ions and nutrients. Variability was 

considered acceptable if the difference was less than 5 percent. 

The difference in concentration between the sample and the 

QA/QC replicate sample (well SU-162) for metals and trace 

elements ranged from 0.5 to 47.5 percent; the median difference was 2.2 percent. The analytes with the largest percent 

differences in concentrations between the sample and its 

replicate were low-concentration analytes where the concentrations were near the laboratory reporting level. The greatest 

difference (47.5 percent) was for molybdenum; the difference 

in concentration between the sample (0.137 μg/L) and the 

replicate sample (0.072 μg/L) was 0.065 μg/L. The laboratory 

detection limit for molybdenum was 0.014 μg/L. The range 

in measured molybdenum concentrations was from less than 

0.014 to 3.78 μg/L.

Physical Properties

Physical properties include temperature, pH, and specific 

conductance. These properties are unstable and are determined 

in the field at the time a water sample is collected. Alkalinity 

and dissolved oxygen concentration also are determined in 

the field. Alkalinity was determined for several samples in the 

laboratory. Summary statistics for physical properties are given 

in table 2, and field values and analytical results are provided 

in table 3.

The USEPA has set maximum contaminant levels (MCLs) 

and secondary maximum contaminant levels (SMCLs) for 

some constituents in drinking water (table 4). MCLs generally 

are set because elevated concentrations of these constituents 

may cause adverse health effects. SMCLs generally are set for 

aesthetic reasons; elevated concentrations of these constituents 

may impart an undesirable taste or odor to water.

pH is a measurement of the activity of hydrogen ions 

in water. pH is expressed in logarithmic units with a pH of 7 

considered neutral. Water with a pH less than 7 is acidic; 

water with a pH greater than 7 is basic. pH values in this 

study ranged from 5.0 to 8.8; the median pH was 6.8 (table 2). 

The pH of 10 of the 20 samples (50 percent) was outside the 

USEPA SMCL range of 6.5 to 8.5 (U.S. Environmental Protection Agency, 2012). Nine samples had a pH less than 6.5, and 

one sample had a pH greater than 8.5 (table 3). 

Water samples from the Burgoon Sandstone Member of 

the Pocono Formation were the most acidic. The median pH of 

water samples from the Burgoon Sandstone Member was 5.9; 

from the Mauch Chunk Formation, 6.6; from the Catskill Formation, 6.9, and from the Huntley Mountain Formation, 7.0.

The alkalinity of a solution is a measure of the capacity for solutes it contains to react with and neutralize acid 

(Hem, 1985, p. 106). Alkalinity ranged from 6.4 to 134 mg/L 

as calcium carbonate; the median concentration was 

62.3 mg/L (table 2). Alkalinity is related to the pH of a water 

sample. In general, water samples with a higher pH have a 

higher alkalinity.

Specific conductance is a measurement of the ability of 

water to conduct an electric current. Specific conductance 

ranged from 42 to 1,280 microsiemens per centimeter (μS/cm); 

the median specific conductance was 218 μS/cm (table 2). 

Median specific conductance values ranged from 187 μS/cm 

for the Catskill Formation to 248 μS/cm for the Huntley Mountain Formation. Specific conductance is related to the dissolved 

solids concentration of a water sample (r2 = 0.98, fig. 4). The 

mean ratio of specific conductance to total dissolved solids was 

0.63 for 20 water samples.

Dissolved oxygen concentrations ranged from 0.1 to 

9.1 mg/L; the median concentration was 4.3 mg/L (table 2). 

Median dissolved oxygen concentrations ranged from 1.5 mg/L 

for the Huntley Mountain Formation to 4.7 mg/L for the Burgoon Sandstone Member. 

0

100

200

300

400

500

600

700

800

0 200 400 600 800 1,000 1,200 1,400

Specific conductance, in microsiemens per centimeter 

at 25 degrees Celsius

Total dissovled solids, in milligrams per liter

Figure 4. Relation between total dissolved solids and specific 

conductance for groundwater samples from wells in Sullivan 

County, Pennsylvania
Baseline Groundwater Quality 

9

Table 2. Summary statistics for physical properties and dissolved gas concentrations in water samples from 20 wells sampled in Sullivan County, Pennsylvania, 2012.[Dissolved gas samples analyzed by the U.S. Geological Survey Chlorofluorocarbon Laboratory in Reston, Virginia; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter at 25 degrees Celsius; CaCO3, calcium carbonate; <, less than; --, unable to compute statistic]

Constituent or property

All wells

Burgoon Sandstone Member 

of the Pocono Formation 

(n=4)

Catskill 

Formation

(n=4)

Huntley Mountain 

Formation 

(n=6)

Mauch Chunk 

Formation 

(n=4)

Minimum Median Maximum Minimum Median Maximum Minimum Median Maximum Minimum Median Maximum Minimum Median Maximum 

pH, field 

(standard units) 5.0 6.8 8.8 5.0 5.9 6.2 5.7 6.9 8.4 5.8 7.0 8.8 5.6 6.6 7.1

Specific conductance, field 

(μS/cm) 42 218 1,280 42 215 370 125 187 1,280 45 248 418 129 227 387

Oxygen, dissolved, field 

(mg/L) 0.1 4.3 9.1 0.3 4.7 5.6 0.9 3.2 7.9 0.2 1.5 9.1 0.1 2.5 7.3

Temperature 

(degrees Celsius) 9.0 11.1 12.4 9.8 10.5 11.8 10.1 11.4 12.4 9.0 10.1 12.3 9.4 11.1 11.6

Alkalinity 

(mg/L as CaCO3) 6.4 62.3 134 6.4 44.0 62.2 38.7 71.5 105 16.2 67.7 134 24.6 62.0 78.2

Methane, dissolved 

(mg/L) <0.001 <0.001 51.1 <0.001 <0.001 0.063 <0.001 <0.001 4.1 <0.001 <0.001 51.1 <0.001 -- 0.052

Carbon dioxide, dissolved 

(mg/L) 0.35 21.8 120 47.0 54.3 120 0.56 20.1 90.4 0.35 12.6 36.4 7.07 32.9 86.9

Nitrogen gas, dissolved 

(mg/L) 17.2 20.4 31.6* 18.9 20.1 23.0 17.2 20.0 22.2 17.6 20.6 22.3 18.9 20.7 24.1

Argon, dissolved 

(mg/L) 0.66 0.73 1.06* 0.68 0.71 0.74 0.66 0.70 0.76 0.66 0.73 0.78 0.69 0.74 0.80

*Allegheny and Pottsville Formations, undivided.
10 Baseline Groundwater Quality from 20 Domestic Wells in Sullivan County, Pennsylvania, 2012 Table 3. Physical properties and dissolved gas concentrations for water samples from 20 wells, Sullivan County, Pennsylvania, 2012. [Locations are shown in figure 2; site information is listed in table1. Dissolved gas samples analyzed by the U.S. Geological Survey Chlorofluorocarbon Laboratory in Reston, Virginia; mg/L, milligrams per liter; <, less than; μS/cm, microsiemens per centimeter at 25 degrees Celsius; --, no data; CaCO3, calcium carbonate. Bold values exceed drinking-water standard] Well- identification number pH, field (standard units) Specific conductance, field (μS/cm) Oxygen, dissolved, field (mg/L) Temperature (degrees Celsius) Alkalinity, field, as CaCO3 (mg/L) Alkalinity, lab, as CaCO3 (mg/L) Methane, dissolved (mg/L) Carbon dioxide, dissolved (mg/L) Nitrogen gas, dissolved (mg/L) Argon, dissolved (mg/L) SU-148 6.8 143 0.3 9.4 -- 78.2 0.002 19.9 21.8 0.77 SU-149 6.2 370 5.6 11.0 62.2 -- <0.001 53.1 18.9 0.68 SU-150 5.8 257 0.3 9.8 -- 44.8 0.06 120 21.2 0.73 SU-151 8.4 1,280 0.9 11.2 77.3 -- 4.1 0.6 22.2 0.76 SU-152 7.2 287 0.6 9.0 97.0 -- <0.001 13.2 21.7 0.74 SU-153 6.3 418 7.9 10.1 42.1 -- <0.001 36.4 20.6 0.73 SU-154 8.8 330 0.2 10.0 -- 134 51.1 0.4 19.1 0.66 SU-155 6.3 311 0.1 11.0 -- 61.7 0.05 45.9 24.1 0.80 SU-156 6.9 147 7.9 12.4 65.7 -- <0.001 18.1 17.2 0.66 SU-157 6.7 111 2.4 11.4 40.0 -- <0.001 11.9 20.6 0.73 SU-158 5.8 45 9.1 12.3 -- 16.2 <0.001 32.4 17.6 0.67 SU-159 7.0 232 7.4 11.5 -- 63.6 <0.001 6.3 20.2 0.73 SU-160 6.9 226 5.2 10.1 105 -- <0.001 22.1 19.7 0.71 SU-161 6.0 172 3.8 10.0 43.1 -- <0.001 47.0 23.0 0.74 SU-162 7.4 209 0.2 9.3 93.3 -- 0.002 8.9 22.3 0.78 SU-163 5.0 42 5.5 11.8 -- 6.4 <0.001 55.5 19.1 0.70 SU-164 7.0 171 5.6 11.8 -- 90.4 0.002 21.5 31.6 1.06 SU-165 5.7 125 1.1 11.6 38.7 -- <0.001 90.4 20.3 0.70 SU-166 5.6 387 4.8 11.6 -- 24.6 <0.001 7.1 18.9 0.72

SU-167 7.1 129 7.3 11.1 62.3 -- <0.001 86.9 19.5 0.69
Baseline Groundwater Quality 11

Table 4. U.S. Environmental Protection Agency maximum contaminant, secondary 

contaminant, and action levels for constituents in drinking water.

[From U.S. Environmental Protection Agency (2012). μg/L, micrograms per liter; mg/L, milligrams per 

liter; pCi/L, picocuries per liter; --, no standard; N, nitrogen]

Regulated constituent Maximum 

contaminant level Action level1 Secondary maximum contaminant level

Aluminum -- -- 50–200 μg/L

Antimony 6 μg/L -- --

Arsenic 10 μg/L -- --

Barium 2 mg/L -- --

Beryllium 4 μg/L -- --

Cadmium 5 μg/L -- --

Chromium, total 100 μg/L -- --

Chloride -- -- 250 mg/L

Copper -- -- 1,000 μg/L

Fluoride 4 mg/L -- 2 mg/L

Iron -- -- 300 μg/L

Lead -- 15 μg/L --

Manganese -- -- 50 μg/L

Nitrate as N 10 mg/L -- --

Nitrite 1 mg/L -- --

pH -- -- 6.5–8.5

Selenium 50 μg/L -- --

Silver -- -- 100 μg/L

Sulfate -- -- 250 mg/L

Total dissolved solids -- -- 500 mg/L

Uranium 30 μg/L -- --

Zinc -- -- 5 mg/L

Gross alpha radioactivity 15 pCi/L -- --

1

Lead is regulated by a treatment technique that requires water purveyors to control the corrosiveness of 

their water. If more than 10 percent of tap-water samples exceed the action level, the water purveyor must 

take additional steps.
12 Baseline Groundwater Quality from 20 Domestic Wells in Sullivan County, Pennsylvania, 2012

Major Ions

Major ions dissolved from soil and rock make up most 

of the dissolved solutes in groundwater; the remainder comes 

mostly from constituents dissolved in precipitation. Summary 

statistics for major ions are given in table 5, and analytical 

results are provided in table 6. Major ions, in order of decreasing median concentration, were calcium, chloride, sodium, 

sulfate, silica, magnesium, potassium, fluoride, and bromide. 

Total dissolved solids (tables 5 and 6) is a measurement 

of the total solutes in water. The USEPA SMCL for total dissolved solids in drinking water is 500 mg/L. The total dissolved solids concentration ranged from 31 to 664 mg/L; the 

median concentration was 130 mg/L. Median total dissolved 

solids concentrations ranged from 123 mg/L in the Catskill 

Formation to 144 mg/L in the Huntley Mountain Formation. 

The total dissolved solids concentration in water from one 

sample exceeded the SMCL. The elevated total dissolved 

solids concentration (664 mg/L) in the water sample from 

well SU-151 in the Catskill Formation was caused by elevated 

concentrations of sodium and chloride. The likely cause of the 

elevated sodium and chloride is connate water in the formation 

and a zone of restricted groundwater flow that limits flushing. 

Chloride concentrations ranged from 0.59 to 342 mg/L; 

the median concentration was 12.9 mg/L. Median chloride 

concentrations ranged from 6.18 mg/L in the Catskill Formation to 39.6 mg/L in the Burgoon Sandstone Member. The 

concentration of chloride (342 mg/L) in the water sample 

from well SU-151 in the Catskill Formation (the geologic unit 

with the lowest median chloride concentration) exceeded the 

USEPA SMCL of 250 mg/L for chloride (tables 5 and 6). 

Nutrients

Nutrients include nitrogen and phosphorus species. 

Nitrogen is found in water principally as nitrate (NO3), nitrite 

(NO2), and ammonia (NH4). The presence of nutrients generally is an indicator of an anthropogenic source(s) of nitrogen, 

which in groundwater might include fertilizers, storm runoff, 

animal wastes, and effluent from septic systems. Summary statistics for nutrients are given in table 7, and analytical results 

are provided in table 8. Concentrations of nutrients in samples 

from the 20 wells were low. Nitrite, ammonia, and orthophosphorus were present in concentrations less than 0.3 mg/L. 

Median concentrations of ammonia (less than 0.01 mg/L) and 

nitrite (less than 0.001 mg/L) were below the laboratory detection limit. 

Nitrate is the most prevalent nitrogen species in groundwater (table 7). Because concentrations of nitrite are so low, 

nitrate plus nitrite concentrations represent nitrate concentrations. The concentration of nitrate as nitrogen ranged from 

less than 0.04 to 1.95 mg/L; the median concentration was 

0.245 mg/L. All nitrate concentrations were well below the 

USEPA MCL of 10 mg/L.

Metals and Trace Elements

Metals and other trace elements typically are present in 

concentrations less than 1 mg/L in natural waters (Hem, 1985). 

Most of the metals and trace elements in natural groundwater 

are leached from the soil or dissolved from the underlying 

bedrock in minute quantities by circulating groundwater. Some 

are present in precipitation. 

Summary statistics for metals and trace elements are 

listed in table 9, and analytical results are provided in table 10. 

The USEPA has established MCLs and SMCLs for some of 

these constituents in drinking water (table 4). Of these constituents, only iron and manganese concentrations exceeded 

the USEPA water-quality standards (table 9). 

Elevated concentrations of iron may cause the water to 

be a yellowish or orange color. Elevated concentrations of iron 

and manganese in water may impart a bitter taste and stain 

laundry and plumbing fixtures. Concentrations of dissolved 

iron in water from the 20 sampled wells ranged from less than 

3.2 to 6,590 μg/L; the median concentration was 11.5 μg/L 

(table 9). Median dissolved iron concentrations ranged from 

4.82 μg/L for the Huntley Mountain Formation to 154 μg/L 

for the Mauch Chunk Formation. Water samples from 4 of the 

20 sampled wells (20 percent) exceeded the USEPA SMCL of 

300 μg/L. Sources of iron in well water include minerals in the 

bedrock, corrosion of iron well casings, and bacterial activity. 

Concentrations of dissolved manganese in water from the 

20 sampled wells ranged from less than 0.13 to 1,710 μg/L; 

the median concentration was 38.5 μg/L (table 9). Median 

manganese concentrations ranged from 4.37 μg/L for the 

Catskill Formation to 336 μg/L for the Mauch Chunk Formation. Water samples from 7 of the 20 sampled wells (35 percent) exceeded the USEPA SMCL of 50 μg/L. Three of the 

four water samples (75 percent) from the Mauch Chunk 

Formation exceeded the USEPA SMCL for manganese. 

Radionuclides

Analyses for radioactivity and radionuclides included 

gross alpha radioactivity, gross beta radioactivity, and dissolved radon-222 (radon gas). Uranium, a radioactive element, 

also was analyzed. Although radionuclides are naturally present in the groundwater of Sullivan County, they may present 

a health problem if activities are elevated (see U.S. Environmental protection Agency, 2013b). Summary statistics for 

radioactive constituents are given in table 11, and analytical 

results are provided in table 12. The USEPA has established 

or proposed MCLs for some of these constituents in drinking 

water (table 4).

Radioactivity is the release of energy and energetic particles by changes in the structure of certain unstable elements 

as they break down to form more stable arrangements. Radioactive energy is released as (1) alpha radiation consisting of 

positively charged helium nuclei, (2) beta radiation consisting 
Baseline Groundwater Quality 13

of electrons or positrons, and (3) gamma radiation consisting 

of electromagnetic waves. 

The most commonly used unit for radioactivity in water 

is picocuries per liter (pCi/L). One Curie is the activity of 

1 gram of radium, which is equal to 3.7 × 1010 atomic disintegrations per second. Activity refers to the number of particles 

emitted by a radionuclide. The rate of decay is proportional 

to the number of atoms present and inversely proportional 

to half-life. The half-life is the amount of time it takes for a 

radioactive element to decay to one half its original quantity.

Naturally occurring radioactivity in groundwater is produced primarily by the radioactive decay of uranium-238 and 

thorium-232. These isotopes disintegrate in steps, forming a 

series of radioactive nuclide “daughter” products, mostly short 

lived, until a stable lead isotope is produced. The uranium-238 

decay series produces the greatest amount of radioactivity in 

natural ground water (Hem, 1985, p. 147). Uranium-238 has 

a half-life of 4.5 × 109 years. Its daughter products include 

radium-226 (half-life of 1,620 years) and radon-222 (half-life 

of 3.8 days). Radon-222, a decay product of radium-226, is a 

colorless, odorless, chemically inert, alpha-particle-emitting 

gas, which is soluble in water. The end product of the decay 

series is the stable isotope lead-206.

Activities of radon-222 in water from the 20 sampled 

wells ranged from 169 to 15,300 pCi/L; the median activity 

was 990 pCi/L (table 11). Median radon-222 activities ranged 

from 680 pCi/L in the Mauch Chunk Formation to 1,390 pCi/L 

in the Catskill Formation. The USEPA does not currently 

regulate radon-222 in drinking water. However, under the 

framework specified by the 1999 Notice for the Proposed 

Radon in Drinking Water Rule (Federal Register, 1999), the 

USEPA proposed an alternative maximum contaminant level 

(AMCL) of 4,000 pCi/L for radon-222 for community water 

systems that use groundwater for all or some of the supply 

in states with an enhanced indoor radon program. For states 

without an enhanced indoor air program, the USEPA proposed 

an MCL of 300 pCi/L for radon-222. Water samples from 17 

of the 20 wells sampled (85 percent) exceeded the proposed 

USEPA MCL of 300 pCi/L; however, only two water samples 

(10 percent of sampled wells) exceeded the proposed USEPA 

AMCL of 4,000 pCi/L for radon-222. All four of the water 

samples from the Catskill Formation exceeded the proposed 

USEPA MCL.

The gross alpha-particle radioactivity in water from the 

20 sampled wells ranged from less than the detection limit to 

33 pCi/L; the median activity was 1.5 pCi/L (table 11). The 

USEPA has established an MCL of 15 pCi/L for gross alphaparticle activity (table 4). One water sample exceeded the 

USEPA MCL. 

The concentration of uranium ranged from less than 

0.004 to 6.35 μg/L; the median concentration was 0.152 μg/L. 

No water samples exceeded the USEPA MCL of 30 μg/L 

for uranium. 

Dissolved Gases

Dissolved gases analyzed are methane, carbon dioxide, 

nitrogen, argon, oxygen, and radon-222. Radon-222 was 

discussed in the “Radionuclides” section, and oxygen was discussed in the “Physical Properties” section. Summary statistics 

for the other dissolved gases are given in table 2, and analytical results are provided in table 3.

Concentrations of dissolved methane ranged from less 

than 0.001 to 51.1 mg/L (table 2). Methane was not detected 

in water samples from 13 of the wells (table 3). The dissolved 

methane concentrations in water from two wells, SU-151 

(Catskill Formation) and SU-154 (Huntley Mountain Formation) were 4.1 and 51.1 mg/L, respectively. A dissolved methane concentration greater than 28 mg/L indicates that potentially explosive or flammable quantities of the gas are being 

produced (Eltschlager and others, 2001, p. 40). A very strong 

odor of hydrogen sulfide was noted during the sampling of 

well SU-154. Water from these 2 wells were the only samples 

from the 20 wells sampled with a pH greater than 8.

Samples of water from wells SU-151 and SU-154 

were also analyzed for the hydrocarbon gases ethane, 

ethylene, propane, iso-butane, and N-butane and for the 

hydrocarbon liquids iso-pentane, N-pentane, and hexane. 

Ethane concentrations of 0.002 and 0.02 mg/L were 

measured in the water samples from wells SU-151 and 

SU-154, respectively. The other hydrocarbons were 

not detected.

Samples of water from wells SU-151 and SU-154 were 

analyzed for isotopes of carbon and hydrogen in the methane. 

The δ13C values were -48.65 and -42. 37 per mil, and the δD 

values were -170.2 and -226.6 per mil for wells SU-151 and 

SU-154, respectively. These values fall within the range for 

a thermogenic natural gas source, rather than a microbial 

(biogenic) gas source (fig. 5). The water sample from well 

SU-151 had the highest concentrations of arsenic, bromide, 

chloride, lithium, molybdenum, and sodium; the second 

highest concentrations of barium, boron, and strontium; and 

the third highest concentrations of fluoride of the 20 wells 

sampled. The water sample from well SU-154 had the highest concentrations of boron and fluoride; the second highest 

concentration of bromide and sodium; and the third highest 

concentration of arsenic, lithium, molybdenum, and strontium 

of the 20 wells sampled.
14 Baseline Groundwater Quality from 20 Domestic Wells in Sullivan County, Pennsylvania, 2012 Table 5. Summary statistics for concentrations of major ions in water samples from 20 wells, Sullivan County, Pennsylvania, 2012. [All constituent conentrations are in milligrams per liter; --, no water-quality standard; n, number of samples; <, less than] Dissolved constituent All wells Burgoon Sandstone Member of the Pocono Formation (n=4) Catskill Formation (n=4) Huntley Mountain Formation (n=6) Mauch Chunk Formation (n=4) Minimum Median Maximum Secondary maximum contaminant level1 Number of samples exceeding standard Minimum Median Maximum Minimum Median Maximum Minimum Median Maximum Minimum Median Maximum CATIONS Calcium 2.64 25.4 41.9 -- -- 2.64 24.4 37.1 14.4 21.5 28.6 6.17 20.8 41.9 23.0 26.6 37.3 Magnesium 1.07 2.73 9.66 -- -- 1.26 4.27 5.85 1.11 1.66 2.42 1.07 3.31 9.66 2.67 3.43 5.75 Potassium 0.44 0.90 4.47 -- -- 0.53 2.46 3.14 0.55 1.09 4.47 0.44 0.71 0.96 0.77 1.06 1.90 Sodium 0.42 8.08 236 -- -- 2.26 4.07 27.8 4.51 18.0 236 1.13 12.3 66.4 0.42 4.12 40.6 ANIONS Bromide 20.018 0.026 2.68 -- -- 0.020 0.030 0.043 0.019 0.024 2.68 0.019 0.029 0.26 0.019 0.029 0.047 Chloride 0.59 12.9 342 250 1 5.0 24.6 72.5 0.98 6.18 342.0 0.59 17.2 94 0.66 23.4 81.5 Fluoride <0.04 0.06 0.45 2 0 <0.04 0.04 0.08 <0.04 0.14 0.23 <0.04 0.06 0.45 <0.04 0.06 0.08 Sulfate 0.68 6.96 26.1 250 0 3.29 8.28 14.9 1.79 9.01 13.2 0.68 4.16 12.4 2.09 6.86 26.1 OTHERS Silica 4.54 6.20 8.12 -- -- 4.54 6.23 7.17 6.29 6.56 8.12 5.21 5.89 6.79 5.86 6.64 7.30 Total dissolved solids 31 130 664 500 1 31 128 223 75 123 664 37 144 318 84 127 251

1From U.S. Environmental Protection Agency (2012).2Allegheny and Pottsville Formations, undivided.
Baseline Groundwater Quality 15

Table 6. Concentrations of major ions in water samples from 20 wells, Sullivan County, Pennsylvania, 2012.[Well locations are shown in figure 2; site information is listed in table1.All concentrations are in milligrams per liter; °C, degrees Celsius; <, less than; Bold values exceed drinking-water standard (U.S. Environmental Protection Agency, 2012)]

Wellidentification 

number

Calcium, 

dissolved

Magnesium,

dissolved

Sodium, 

dissolved

Potassium, 

dissolved

Bromide, 

dissolved

Chloride, 

dissolved

Fluoride, 

dissolved

Silica, 

dissolved

Sulfate, 

dissolved

Dissolved solids 

dried at 180°C

SU-148 25.2 3.98 1.15 0.90 0.02 1.75 0.08 6.1 2.09 90SU-149 37.1 5.76 27.8 1.82 0.043 72.5 0.08 5.39 10.3 223SU-150 25.5 5.85 2.87 3.14 0.033 39.3 0.06 7.06 6.25 156SU-151 14.4 1.11 236 1.6 2.68 342 0.22 6.76 1.79 664SU-152 40.8 5.21 9.07 0.96 0.02 19.1 0.07 5.21 12.4 162SU-153 41.9 9.66 21.8 0.9 0.037 94 <0.04 5.79 7.36 318SU-154 13.1 1.64 66.4 0.60 0.261 34.1 0.45 6.79 0.68 206SU-155 37.3 5.75 7.08 1.21 0.047 45.1 0.06 7.18 9.8 164SU-156 28.6 2.42 4.51 0.55 0.019 0.98 <0.04 8.12 7.91 99SU-157 15.6 3.95 1.17 0.60 0.021 10.6 0.05 5.76 0.96 76SU-158 6.17 1.07 1.13 0.44 0.019 0.59 0.05 6.35 6.55 37SU-159 29.3 2.39 13.5 0.61 0.197 25.6 0.05 6.03 11.1 134SU-160 27.1 1.82 31.3 0.58 0.025 5.51 0.23 6.29 13.2 147SU-161 23.2 2.78 5.27 3.1 0.027 9.88 <0.04 7.17 14.9 100SU-162 25.9 2.67 15.5 0.81 0.133 15.3 0.08 5.98 1.77 125SU-162 replicate 26.1 2.66 15.4 0.79 0.136 15.2 0.08 5.97 1.75 125SU-163 2.64 1.26 2.26 0.53 0.02 5.00 0.02 4.54 3.29 31SU-164 19.2 6.19 9.28 1.43 0.018 0.76 0.14 6.1 4.52 109SU-165 15.8 1.49 4.77 4.47 0.023 6.85 0.06 6.36 10.1 75SU-166 27.9 2.87 40.6 1.9 0.039 81.5 0.05 7.3 26.1 251SU-167 23.0 2.67 0.42 0.77 0.019 0.66 <0.04 5.86 3.91 84
16 Baseline Groundwater Quality from 20 Domestic Wells in Sullivan County, Pennsylvania, 2012 Table 7. Summary statistics for concentrations of nutrients in water samples from 20 wells, Sullivan County, Pennsylvania, 2012. [All constituents are in milligrams per liter; n, number of samples; N, nitrogen; P, phosphorus; <, less than; NS, unable to compute statistic; --, no water-quality standard] Dissolved constituent All wells Burgoon Sandstone Member of the Pocono Formation (n=4) Catskill Formation (n=4) Huntley Mountain Formation (n=6) Mauch Chunk Formation (n=4) Minimum Median Maximum Maximum contaminant level1 Minimum Median Maximum Minimum Median Maximum Minimum Median Maximum Minimum Median Maximum Ammonia, dissolved (as N) <0.01 <0.01 0.241 -- <0.01 NS 0.241 <0.01 <0.01 0.127 <0.01 <0.01 0.124 <0.01 NS 0.081 Nitrate plus nitrite, dissolved (as N) <0.04 0.245 1.95 -- <0.04 1.02 1.29 0.172 0.961 1.80 <0.04 0.196 1.07 <0.04 NS 1.95 Nitrate, dissolved (as N) <0.04 0.245 1.95 10 <0.04 1.02 1.29 0.172 0.958 1.80 <0.04 0.196 1.07 <0.04 NS 1.95 Nitrite, dissolved (as N) <0.001 <0.001 0.005 1 <0.001 <0.001 0.001 <0.001 <0.001 0.005 <0.001 NS 0.001 <0.001 <0.001 0.002 Orthophosphate, dissolved (as P) <0.004 NS 0.045 -- <0.004 <0.004 0.012 0.005 0.012 0.018 <0.004 NS 0.045 <0.004 NS 0.017

1 From U.S. Environmental Protection Agency (2012).
Baseline Groundwater Quality 17

Table 8. Concentrations of nutrients in water samples from 20 wells, Sullivan County, Pennsylvania, 2012.

[Well locations are shown in figure 2; site information is listed in table1. mg/L, milligrams per liter; N, nitrogen; P, phosphorus; <, less than]

Wellidentification 

number

Ammonia, 

dissolved

(mg/L as N)

Nitrate plus 

nitrite, dissolved

(mg/L as N)

Nitrate, 

dissolved

(mg/L as N)

Nitrite, 

dissolved 

(mg/L as N)

Orthophosphate, 

dissolved

(mg/L as P)

SU-148 0.075 <0.04 < 0.04 <0.001 <0.004

SU-149 0.014 0.256 0.256 <0.001 <0.004

SU-150 0.241 <0.04 < 0.039 0.001 <0.004

SU-151 0.127 0.332 0.327 0.005 0.005

SU-152 <0.01 0.159 0.158 0.001 <0.004

SU-153 <0.01 1.07 1.07 0.001 0.005

SU-154 0.124 <0.04 < 0.039 0.001 0.045

SU-155 0.081 <0.04 < 0.038 0.002 <0.012

SU-156 <0.01 1.8 1.8 <0.001 0.018

SU-157 <0.01 0.622 0.622 <0.001 <0.004

SU-158 <0.01 0.233 0.233 <0.001 0.015

SU-159 <0.01 0.415 0.415 <0.001 <0.004

SU-160 <0.01 0.172 0.172 <0.001 0.011

SU-161 <0.01 1.29 1.29 <0.001 0.012

SU-162 0.055 <0.04 <0.04 <0.001 <0.004

SU-162 replicate 0.056 < 0.04 <0.04 <0.001 <0.004

SU-163 <0.01 0.741 0.741 <0.001 <0.004

SU-164 0.229 <0.04 <0.04 <0.001 <0.004

SU-165 <0.01 1.59 1.59 <0.001 0.012

SU-166 <0.01 1.95 1.95 <0.001 0.017

SU-167 <0.01 0.234 0.234 <0.001 0.006
18 Baseline Groundwater Quality from 20 Domestic Wells in Sullivan County, Pennsylvania, 2012 Table 9. Summary statistics for concentrations of metals and trace elements in samples from 20 wells, Sullivan County, Pennsylvania, 2012. [All concentrations are in micrograms per liter; water-quality standards from U.S. Environmental Protection Agency (2012); n, number of samples; --, no standard; <, less than; NS, could not compute statistic] Dissolved constituent All wells Water-quality standard1 Number of samples exceeding standard Percentage of samples exceeding standard Burgoon Sandstone Member of the Pocono Formation (n=4) Minimum Median Maximum Maximum contaminant level Action level2 Secondary maximum contaminant level Minimum Median Maximum Aluminum <2.2 <2.2 26.3 -- -- 50–200 0 0 <2.2 <2.2 18.5 Antimony <0.027 <0.027 0.294 6 -- -- 0 0 <0.027 NS 0.251 Arsenic <0.03 0.30 8.85 10 -- -- 0 0 <0.03 0.093 0.67 Barium 5.89 140 1,050 2,000 -- -- 0 0 24 159 1,050 Beryllium <0.006 0.010 0.125 4 -- -- 0 0 0.01 0.034 0.125 Boron 4 20 153 -- -- -- -- -- 7 22 91 Cadmium <0.016 <0.016 0.112 5 -- -- 0 0 0.021 NS 0.072 Chromium <0.07 <0.07 0.3 100 -- -- 0 0 <0.07 <0.07 0.1 Cobalt <0.021 0.062 8.04 -- -- -- -- -- 0.052 0.16 0.47 Copper <0.80 4.2 130 -- -- 1,000 0 0 <0.80 14.2 70.6 Iron <3.2 11.5 6,590 -- -- 300 4 20 <3.20 115 6,590 Lead <0.025 0.364 7.36 -- 15 -- 0 0 <0.025 0.813 2.48 Lithium 0.48 5.73 457 -- -- -- -- -- 1.29 6.59 41.5 Manganese <0.13 38.5 1,710 -- -- 50 7 35 40.1 42.6 1,710 Molybdenum <0.014 0.126 3.78 -- -- -- -- -- <0.014 NS 0.124 Nickel <0.09 0.42 4.3 -- -- -- -- -- 0.42 1.3 4.3 Selenium <0.03 0.08 0.95 50 -- -- 0 0 <0.03 0.14 0.95

Silver <0.005 <0.005 0.11 -- -- 100 0 0 <0.005 <0.005 0.006Strontium 13.4 221 2,450 -- -- -- -- -- 647 1,048 1,180Zinc <1.4 9.2 44.4 -- -- 5,000 0 0 10.2 24.7 25.5
Baseline Groundwater Quality 19

Table 9. Summary statistics for concentrations of metals and trace elements in samples from 20 wells, Sullivan County, Pennsylvania, 2012.—Continued[All concentrations are in micrograms per liter; water-quality standards from U.S. Environmental Protection Agency (2012); n, number of samples; --, no standard; <, less than; NS, could not compute statistic]

Dissolved 

constituent

Catskill Formation

(n=4)

Huntley Mountain Formation

(n=6)

Mauch Chunk Formation

(n=4)

Minimum Median Maximum Minimum Median Maximum Minimum Median Maximum

Aluminum <2.2 4.06 26.3 <2.2 <2.2 5.12 <2.2 <2.2 14.2Antimony 0.043 0.084 0.131 <0.027 <0.027 0.294 <0.027 <0.027 0.092Arsenic 0.217 3.47 8.85 <0.03 0.258 4.97 0.096 0.934 2.54Barium 81 140 415 5.89 167 304 88 170 354Beryllium 0.008 0.010 0.057 <0.006 0.007 0.017 <0.006 0.014 0.775Boron 9 43 150 5 25 153 4 16 43Cadmium <0.016 NS 0.031 <0.016 <0.016 <0.016 <0.016 0.030 0.112Chromium <0.07 0.1 0.3 <0.07 NS 0.1 <0.07 <0.07 0.2Cobalt 0.063 0.065 0.076 <0.021 0.024 0.037 <0.021 1.21 8.04Copper 4.7 22.0 130 <0.80 <0.80 21.2 1.9 8.6 70.2Iron <3.20 7.58 84.8 <3.20 4.82 523 <3.20 154 6,100Lead 0.198 0.714 2.42 <0.025 0.143 1.44 0.172 0.277 7.36Lithium 0.48 15.5 457 0.55 3.91 38.5 1.91 6.38 19.4Manganese 0.34 4.37 69.3 0.161 14.5 316 <0.13 336 765Molybdenum 0.044 1.16 3.78 <0.014 0.096 1.15 <0.014 0.107 0.335Nickel 0.20 0.30 1.2 <0.09 0.18 1.4 0.21 2.4 3.9Selenium 0.06 0.26 0.53 <0.03 NS 0.15 <0.03 NS 0.55Silver <0.005 NS 0.11 <0.005 <0.005 0.007 <0.005 <0.005 0.007Strontium 45.2 82.5 2,380 13.4 173 1,210 121 212 2,450Zinc 6.6 8.3 24.9 <1.4 4.2 13.3 2.4 11.2 44.4

1 From U.S. Environmental Protection Agency (2012).2 Lead is regulated by a treatment technique that requires water purveyors to control the corrosiveness of their water. If more than 10 percent of tap-water samples exceed 

the action level, the water purveyor must take additional steps.
20 Baseline Groundwater Quality from 20 Domestic Wells in Sullivan County, Pennsylvania, 2012 Table 10. Concentrations of metals and trace elements in samples from 20 wells, Sullivan County, Pennsylvania, 2012. [Well locations are shown in figure 2; site information is listed in table 1. All concentrations are in micrograms per liter; <, less than; bold values exceed drinking-water standard] Well- identification number Aluminum, dissolved Antimony, dissolved Arsenic, dissolved Barium, dissolved Beryllium, dissolved Boron, dissolved Cadmium, dissolved Chromium, dissolved Cobalt, dissolved Copper, dissolved SU-148 <2.2 0.092 2.5 246 0.020 21 0.026 <0.07 8.04 1.9 SU-149 <2.2 0.251 0.11 288 0.018 91 <0.016 <0.07 0.052 6.4 SU-150 <2.2 <0.027 0.67 1,050 0.050 28 <0.016 <0.07 0.467 <0.80 SU-151 2.4 0.043 8.9 415 0.011 150 0.031 <0.07 0.064 4.7 SU-152 <2.2 0.294 0.36 286 <0.006 82 <0.016 <0.07 0.021 <0.80 SU-153 <2.2 <0.027 0.16 65.4 0.017 5 <0.016 0.08 0.037 3.7 SU-154 5.1 <0.027 5.0 304 0.007 153 <0.016 0.1 <0.021 <0.80 SU-155 <2.2 <0.027 1.7 354 0.009 11 0.033 <0.07 2.36 13.7 SU-156 <2.2 0.095 1.8 121 0.008 9 <0.016 0.10 0.076 39.3 SU-157 <2.2 <0.027 <0.03 5.89 <0.006 6 <0.016 <0.07 0.029 <0.80 SU-158 3.7 <0.027 0.14 8.79 0.007 5 <0.016 0.11 0.024 21.2 SU-159 <2.2 0.049 0.24 74.2 <0.006 11 <0.016 <0.07 0.03 1.3 SU-160 5.72 0.074 5.1 81 0.010 66 <0.016 0.1 0.063 4.7 SU-161 <2.2 0.031 0.08 24 0.01 15 0.021 0.08 0.217 70.6 SU-162 <2.2 <0.027 0.37 268 0.010 45 <0.016 <0.07 0.024 <0.80 SU-162 replicate < 2.2 <0.027 0.39 271 0.008 44 <0.016 <0.07 <0 .021 <0.80 SU-163 18.5 <0.027 <0.03 29 0.125 7 0.072 <0.07 0.095 22 SU-164 <2.2 <0.027 1.3 317 0.014 40 <0.016 <0.07 0.979 <0.80 SU-165 26.3 0.131 0.22 159 0.057 19 0.028 0.3 0.065 130 SU-166 14.2 <0.027 0.10 94 0.078 43 0.112 0.15 0.062 70.2

SU-167 <2.2 <0.027 0.22 88.2 <0.006 4 <0.016 <0.07 <0.021 3.5
Baseline Groundwater Quality 21

Table 10. Concentrations of metals and trace elements in samples from 20 wells, Sullivan County, Pennsylvania, 2012.—Continued[Well locations are shown in figure 2; site information is listed in table1. All concentrations are in micrograms per liter; <, less than; bold values exceed drinking-water standard]

Wellidentification 

number

Iron, 

dissolved

Lead, 

dissolved

Lithium, 

dissolved

Manganese, 

dissolved

Molybdenum,

dissolved

Nickel,

dissolved

Selenium,

dissolved

Silver,

dissolved

Strontium,

dissolved

Zinc,

dissolved

SU-148 292 0.352 8.89 598 0.335 1.8 <0.03 <0.005 265 8.2SU-149 <3.2 <0.025 11.6 43.5 0.124 1.4 0.03 0.01 2,450 25.1SU-150 6,590 0.375 41.5 1,710 <0.014 0.42 <0.03 <0.005 1,150 10.2SU-151 9.4 0.198 457 69.3 3.78 0.38 0.22 0.11 945 6.6SU-152 <3.2 0.218 6.01 0.16 0.274 0.18 <0.03 0.01 2,380 4.0SU-153 4.2 0.647 1.8 0.44 0.024 0.41 0.10 <0.005 177 4.5SU-154 27.7 0.038 38.5 36.8 1.15 <0.09 <0.03 <0.005 1,210 <1.4SU-155 6,100 0.172 19.4 765 0.065 2.9 <0.03 <0.005 168 44.4SU-156 <3.2 0.695 4.12 0.40 0.62 0.2 0.31 <0.005 159 8.1SU-157 4.7 <0.025 0.55 28.6 0.056 0.13 0.15 <0.005 73.4 <1.4SU-158 5.0 1.44 0.56 0.37 <0.014 1.4 0.05 <0.005 17.5 13.3SU-159 10 0.15 5.45 1.06 0.128 0.17 0.15 <0.005 265 9.9SU-160 5.8 0.733 26.8 0.34 1.7 0.22 0.53 <0.005 265 8.5SU-161 13 1.25 1.29 40.1 0.055 1.2 0.95 <0.005 45.2 24.3SU-162 523 0.068 20.2 316 0.137 0.17 <0.03 <0.005 1,180 10.8SU-162 replicate 520 0.044 20.1 311 0.072 0.13 <0.03 <0.005 1,200 10.4SU-163 217 2.48 1.57 41.6 <0.014 4.3 0.24 <0.005 13.4 25.5SU-164 1,790 0.782 21.2 233 0.268 0.73 <0.03 <0.005 647 4.2SU-165 84.8 2.42 0.48 8.34 0.044 1.2 0.06 0.01 50 24.9SU-166 15.8 7.36 3.87 73 <0.014 3.9 0.55 0.01 91.6 14.2SU-167 <3.2 0.201 1.91 <0.130 0.148 0.21 0.41 <0.005 121 2.4
22 Baseline Groundwater Quality from 20 Domestic Wells in Sullivan County, Pennsylvania, 2012 Table 11. Summary statistics for concentrations and activities of radioactive constituents in samples from 20 wells, Sullivan County, Pennsylvania, 2012. [Gross alpha and beta radioactivity analyses by Eberline Corporation of Redmond, California; μg/L, micrograms per liter; pCi/L, picocuries per liter; --, no standard; n, number of samples; R, not detected, result below sample specific critical level; <, less than; NS, unable to compute statistic] Constituent All wells Water-quality standard Burgoon Sandstone Member of the Pocono Formation (n=4) Minimum activity or concentration Median activity or concentration Maximum activity or concentration Maximum contaminant level1 Proposed maximum contaminant level2 Number of samples exceeding standard Percentage of samples exceeding standard Minimum activity or concentration Median activity or concentration Maximum activity or concentration Gross alpha radioactivity, total (pCi/L) 

R 1.5 33 15 -- 1 5 R 1.8 33

Gross beta radioactivity, 

total (pCi/L) 

R 2 21 -- -- -- -- 1.1 2.8 21

Radon-222, dissolved

(pCi/L) 3169 990 15,300 -- 300 17 85 178 1,080 1,630

Uranium, dissolved

(μg/L) <0.004 0.152 6.35 30 -- 0 0 <0.004 0.087 0.465

Constituent

Catskill Formation

(n=4)

Huntley Mountain Formation

(n=6)

Mauch Chunk Formation

(n=4)

Minimum 

activity or 

concentration

Median 

activity or 

concentration

Maximum activity or 

concentration

Minimum 

activity or 

concentration

Median 

activity or 

concentration

Maximum activity or 

concentration

Minimum 

activity or 

concentration

Median 

activity or 

concentration

Maximum activity or 

concentration

Gross alpha radioactivity, 

total (pCi/L) 2.2 3.2 9.1

R NS 2.8

R NS 4.2

Gross beta radioactivity, 

total (pCi/L) 2.2 3.6 4.9

R 1.2 4.0 0.9 1.7 5.7

Radon-222, dissolved

(pCi/L) 410 1,390 1,500 490 990 4,700 280 680 15,300

Uranium, dissolved

(μg/L) 0.229 2.04 6.35 <0.004 0.060 1.58 0.005 0.346 1.82

1From U.S. Environmental Protection Agency (2012).2From Federal Register (1999).3Allegheny and Pottsville Formations, undivided.
Baseline Groundwater Quality 23

Table 12. Concentrations and activities of radioactive constituents in 

samples from 20 wells, Sullivan County, Pennsylvania, 2012.

[Well locations are shown in figure 2; site information is listed in table1; gross alpha and 

beta radioactivity analyses by Eberline Corporation of Redmond, California; μg/L, micrograms per liter; pCi/L, picocuries per liter; --, no replicate sample; R, not detected, result 

below sample specific critical level, value is critical level; <, less than. Bold values exceed 

drinking-water standard or proposed drinking-water standard]

Wellidentification 

number

Gross alpha 

radioactivity, 

total 

(pCi/L) 

Gross beta 

radioactivity, 

total 

(pCi/L) 

Radon-222, 

dissolved

(pCi/L)

Uranium, 

dissolved

(μg/L)

SU-148 4.2 1.8 280 0.636

SU-149 33 21 1,480 0.16

SU-150 2.4 3.2 178 <0.004

SU-151 2.4 4.9 1,390 0.229

SU-152 2.8 2.9 1,000 1.58

SU-153 R 0.6 1.3 2,640 0.144

SU-154 R 1.1 940 0.034

SU-155 R 0.6 0.9 670 0.005

SU-156 3.9 2.2 1,500 3.44

SU-157 1.9 4 4,700 0.086

SU-158 R 0.1 R 0.6 980 <0.004

SU-159 R 0.2 R 0.3 1,140 0.18

SU-160 9.1 2.5 1,390 6.35

SU-161 1.2 2.5 670 0.465

SU-162 0.9 R 0.3 490 0.01

SU-162 replicate -- -- -- 0.009

SU-163 R 1.1 1,630 0.015

SU-164 0.5 1.7 169 0.005

SU-165 2.2 4.7 410 0.644

SU-166 R 0.5 1.5 690 0.056

SU-167 1.8 5.7 15,300 1.82
24 Baseline Groundwater Quality from 20 Domestic Wells in Sullivan County, Pennsylvania, 2012

Microbial Gas

(Carbon Dioxide Reduction)

 Microbial Gas

(Acetate Formation)

Thermogenic Gas

 (Natural Gas)

SU-151

SU-154

-380

-360

-340

-320

-280

-300

-260

-240

-220

-200

-180

-160

-140

-120

-100

-90 -80 -70 -60 -50 -40 -30

δ C , Relative to Vienna Pee Dee Belemnite, in per mil CH4

13

Relative to Vienna Standard Mean δD , CH4

Ocean Water, in per mil

Figure 5. Stable isotopic composition of carbon and hydrogen in dissolved methane in two 

groundwater samples from Sullivan County, Pennsylvania. Diagram shows process end members 

observed in natural systems (Modified from Coleman and others, 1993, based on the dataset of 

Schoell, 1980). Isotope analyses were done by Isotech Laboratories, Inc., in Champaign, Illinois.
Summary 25

Summary

Sullivan County is underlain by the Marcellus Shale, 

which is being tapped as a source of natural gas. Pre-gas well 

drilling groundwater-quality data for water-supply wells in 

the northern part of Sullivan County have been collected by 

the natural-gas industry; however, data are not available for 

the rest of the county. Without baseline data for associated 

water-quality constituents, it is not possible to establish a connection between gas production activities and the well-water 

chemistry that might be affected. This study, done in cooperation with the Pennsylvania Department of Conservation 

and Natural Resources, Bureau of Topographic and Geologic 

Survey (Pennsylvania Geological Survey), provides a pre-gas 

well drilling groundwater-quality baseline for the central and 

southern parts of Sullivan County.

Sullivan County is underlain by surficial bedrock of 

Pennsylvania, Mississippian, and Devonian ages. Alluvium 

overlies the bedrock in the stream valleys. The major bedrock 

geologic formations in the county are the Pennsylvanian age 

Allegheny and Pottsville Formations, undivided; the Mississippian age Mauch Chunk Formation and Burgoon Sandstone 

Member of the Pocono Formation; and the Devonian age 

Catskill and Lock Haven Formations. No wells were sampled 

in the Lock Haven Formation.

Water samples were collected from 20 domestic wells in 

August and September 2012 and analyzed to characterize their 

physical and chemical quality. Samples were analyzed for 47 

constituents and properties, including nutrients, major ions, 

metals and trace elements, radioactivity, and dissolved gases, 

including methane and radon-222. Wells were selected from 

the Pennsylvania Geological Survey (PaGS) Pennsylvania 

Groundwater Information System database. Only wells with 

available construction data were considered. All sampled wells 

are private domestic wells.

The analytical results for the 20 groundwater samples 

collected during this study indicate that only one constituent 

(gross-alpha radioactivity) in one sample was found to exceed 

the U.S. Environmental Protection Agency (USEPA) primary 

drinking water maximum contaminant level (MCL). Water 

samples from 85 percent of the sampled wells exceeded the 

proposed USEPA MCL of 300 picocuries per liter (pCi/L) 

for radon-222; however, only two water samples (10 percent 

of sampled wells) exceeded the proposed USEPA alternate 

maximum contaminant level (AMCL) of 4,000 pCi/L for 

radon-222. In a few samples, the concentrations of total dissolved solids, iron, manganese, and chloride exceeded USEPA 

secondary maximum contaminant levels (SMCL). In addition, 

water samples from two wells contained methane concentrations greater than 1 milligram per liter (mg/L). In general, 

most of the water-quality problems involve aesthetic considerations, such as taste or odor from elevated concentrations 

of total dissolved solids, iron, manganese, and chloride that 

develop from natural interactions of water and rock minerals 

in the subsurface. 

pH ranged from 5.0 to 8.8 with a median value of 6.8. 

The pH of 50 percent of the sampled wells was outside 

the USEPA SMCL range of 6.5 to 8.5. Nine samples had 

a pH less than 6.5, and one sample had a pH greater than 

8.5. The median pH of water samples ranged from 5.9 for 

the Burgoon Sandstone Member to 7.0 for the Huntley 

Mountain Formation.

The total dissolved solids concentration ranged from 

31 to 664 mg/L; the median was 130 mg/L. Median total 

dissolved solids concentrations ranged from 123 mg/L in the 

Catskill Formation to 144 mg/L in the Huntley Mountain Formation. The total dissolved solids concentrations in one water 

sample exceeded the SMCL. The elevated total dissolved 

solids concentration (664 mg/L) in water from well SU-151 in 

the Catskill Formation was caused by elevated concentrations 

of sodium and chloride. 

Chloride concentrations ranged from 0.5.9 to 342 mg/L; 

the median was 12.9 mg/L. Median chloride concentrations 

ranged from 6.18 mg/L in the Catskill Formation to 39.6 mg/L 

in the Burgoon Sandstone Member. The concentration of chloride (342 mg/L) in the water sample from well SU-151 in the 

Catskill Formation exceeded the USEPA SMCL of 250 mg/L 

for chloride.

Concentrations of nutrients were low. Nitrite, ammonia, 

and orthophosphorus were present in concentrations less than 

0.3 mg/L. Median concentrations were less than the laboratory 

detection limit for ammonia and nitrite. Nitrate is the most 

prevalent nitrogen species in groundwater. The calculated 

concentration of nitrate as nitrogen ranged from less than 0.04 

to 1.95 mg/L; the median concentration was 0.245 mg/L. All 

nitrate concentrations were well below the USEPA maximum 

contaminant level (MCL) of 10 mg/L.

Concentrations of dissolved iron ranged from less 

than 3.2 to 6,590 micrograms per liter (μg/L); the median 

concentration was 11.5 μg/L. Median iron concentrations 

ranged from 4.82 μg/L for the Huntley Mountain Formation 

to 154 μg/L for the Mauch Chunk Formation. Water samples 

from 20 percent of the sampled wells exceeded the USEPA 

SMCL of 300 μg/L for iron. 

Concentrations of dissolved manganese ranged from 

less than 0.13 to 1,710 μg/L; the median concentration was 

38.5 μg/L. Median manganese concentrations ranged from 

4.37 μg/L for the Catskill Formation to 336 μg/L for the 

Mauch Chunk Formation. Water samples from 35 percent of 

the sampled wells exceeded the USEPA SMCL of 50 μg/L 

for manganese.

Activities of radon-222 ranged from 169 to 15,300 pCi/L; 

the median activity was 990 pCi/L. Median radon-222 activities ranged from 680 pCi/L in the Mauch Chunk Formation 

to 1,390 pCi/L in the Catskill Formation. Water samples 

from 85 percent of the sampled wells exceeded the proposed 

USEPA MCL of 300 pCi/L for radon-222; however, only 

two water samples exceeded the proposed USEPA AMCL of 

4,000 pCi/L. All four of the water samples from the Catskill 

Formation exceeded the proposed USEPA MCL. The gross 

alpha-particle radioactivity ranged from less than the detection 
26 Baseline Groundwater Quality from 20 Domestic Wells in Sullivan County, Pennsylvania, 2012

limit to 33 pCi/L; the median activity was 1.5 pCi/L. One 

water sample exceeded the USEPA MCL of 15 pCi/L for gross 

alpha-particle activity.

Concentrations of methane ranged from less than 0.001 to 

51.1 mg/L. Methane was not detected in water samples from 

13 of the wells. The methane concentration in water from two 

wells, SU-151 (Catskill Formation) and SU-154 (Huntley 

Mountain Formation), were 4.1 and 51.1 mg/L, respectively. 

Ethane concentrations of 0.002 and 0.02 mg/L were measured 

in the water samples from SU-151 and SU-154, respectively. 

A very strong odor of hydrogen sulfide was noted during the 

sampling of well SU-154. The pH of the water samples for 

both wells was greater than 8.

Samples of water from wells SU-151 and SU-154 were 

analyzed for isotopes of carbon and hydrogen in the methane. 

The values fall in the range for thermogenic natural gas, rather 

than microbial (biogenic) gas. The water sample from well 

SU-151 had the highest concentrations of arsenic, bromide, 

chloride, lithium, molybdenum, and sodium; the second highest concentrations of barium, boron, and strontium; and the 

third highest concentration of fluoride of the 20 wells sampled. 

The water sample from well SU-154 had the highest concentrations of boron and fluoride; the second highest concentrations of bromide and sodium; and the third highest concentrations of arsenic, lithium, molybdenum, and strontium of the 

20 wells sampled.

References Cited

Coleman, D.D., Liu, C.L., Hackley, K.C., and Benson, L.J., 

1993, Identification of landfill methane using carbon and 

hydrogen isotope analysis: Proceedings of Sixteenth International Madison Waste Conference, University of Wisconsin, September 22–23, 1993, p. 303–314.

Edmunds, W.E., 1996, Correlation chart showing suggested 

revisions of uppermost Devonian through Permian stratigraphy, Pennsylvania: Pennsylvania Geological Survey, 

4th ser., Open-File Report 96–49, 12 p.

Eltschlager, K.K., Hawkins, J.W., Ehler, W.C., and Baldassare, Fred, 2001, Technical measures for the investigation 

and mitigation of fugitive methane hazards in areas of coal 

mining: U.S. Office of Surface Mining Reclamation and 

Enforcement, 125 p.

Federal Register, 1999, National Primary Drinking Water 

Regulations; Radon-222: Federal register, v. 64, no. 211, 

p. 59245–59294.

Hem, J.D., 1985, Study and interpretation of the chemical 

characteristics of natural water (3d ed.): U.S. Geological 

Survey Water-Supply Paper 2254, 264 p.

Kargbo, D.M., Wilhelm, R.G., and Campbell, D.J., 2010, Natural gas plays in the Marcellus shale—Challenges and potential opportunities: Environmental Science and Technology, 

v 44, p. 5679–5684.

Kerr, R.A., 2010, Natural gas from shale bursts onto the scene: 

Science, v. 328, p. 1624–1626.

LaMotte, A.E., 2008, National Land Cover Database 2001 Tile 

2, northeast United States: U.S. Geological Survey digital 

data, accessed July 5, 2012, at http://water.usgs.gov/lookup/

getspatial?nlcd01_2.

Miles, C.E., and Whitfield, T.G., comps., 2001, Bedrock geology of Pennsylvania: Pennsylvania Geological Survey, 

4th ser., digital dataset, scale 1:250,000.

Pennsylvania Department of Conservation and Natural 

Resources, 2010, DCNR State Forest Lands 2010: Bureau 

of Forestry, digital dataset, accessed on November 7, 

2012, at http://www.pasda.psu.edu/uci/MetadataDisplay.

aspx?entry=PASDA&file=dcnr_stateforestlands_2010.

xml&dataset=263. 

Pennsylvania Department of Conservation and Natural 

Resources, 2011, DCNR State Parks 201109: Bureau of 

State Parks, digital dataset, accessed on November 7, 

2012, at http://www.pasda.psu.edu/uci/MetadataDisplay.

aspx?entry=PASDA&file=DCNR_StateParks201109.

xml&dataset=114.

Pennsylvania Department of Environmental Protection, 2012a, 

Year to date permits issued by well type, accessed December 5, 2012, at http://www.depreportingservices.state.pa.us/

ReportServer/Pages/ReportViewer.aspx?/Oil_Gas/Permits_

Issued_Count_by_Well_Type_YTD.

Pennsylvania Department of Environmental Protection, 2012b, 

Wells drilled by county, accessed December 5, 2012, at http://

www.depreportingservices.state.pa.us/ReportServer/Pages/

ReportViewer.aspx?/Oil_Gas/Wells_Drilled_By_County.

Pennsylvania Department of Transportation, 2009a, PennDOT 

- Pennsylvania municipality boundaries 2009: Pennsylvania Department of Transportation, Bureau of Planning and 

Research, Cartographic Information Division, digital dataset, 

accessed on October 9, 2012, at http://www.pasda.psu.edu/

uci/MetadataDisplay.aspx?entry=PASDA&file=PaMunicipali

ties2009_01.xml&dataset=41.

Pennsylvania Department of Transportation, 2009b, PennDOT 

- Pennsylvania county boundaries 2009: Pennsylvania 

Department of Transportation, Bureau of Planning and 

Research, Cartographic Information Division, digital dataset, accessed on October 9, 2012, at http://www.pasda.psu.

edu/uci/MetadataDisplay.aspx?entry=PASDA&file=PaCou

nty2009_01.xml&dataset=24.
References Cited 27

Pennsylvania Game Commission, 2011, PGC State Game 

Lands 201108: digital dataset accessed November 7, 

2012, at http://www.pasda.psu.edu/uci/MetadataDisplay.

aspx?entry=PASDA&file=PGC_StateGameland201108.

xml&dataset=86.

Pennsylvania Geological Survey, 2012, Pennsylvania groundwater information system (PAGWIS) documentation, 

accessed October 3, 2012, at http://www.dcnr.state.pa.us/

topogeo/groundwater/PaGWIS/help.aspx. 

PRISM Group at Oregon State University, 2013, Precipitation and average minimum and maximum temperature, 1971–2000: PRISM Group at Oregon State 

University digital data, accessed February 15, 2013, 

at http://www.prism.oregonstate.edu/products/matrix.

phtml?vartype=tmax&view=data.

Sevon, W.D., 2000, Physiographic provinces of Pennsylvania: 

Pennsylvania Geological Survey, 4th ser., Map 13, 1 sheet.

Schoell, M., 1980, The hydrogen and carbon isotopic composition of methane from natural gases of various origins: 

Geochimica et Cosmochimica Acta, v. 44, p. 649–661.

Sullivan County Planning and Economic Development Office, 

2010, Sullivan County comprehensive plan: Sullivan 

County Planning and Economic Development Office, 175 p. 

Taylor, L.E., Werkheiser, W.H., and Kriz, M.L., 1983, Groundwater resources of the West Branch Susquehanna River 

Basin, Pennsylvania: Pennsylvania Geological Survey, 4th 

ser., Water Resource Report 56, 143 p. 

U.S. Census Bureau, 2013, 2010 census interactive population 

search, accessed January 28, 2013, at http://www.census.

gov/2010census/popmap/ipmtext.php?fl=42.

U.S. Environmental Protection Agency, 2006, Drinking water 

standards and health advisories: U.S. Environmental Protection Agency EPA 822–R–06–013, 12 p.

U.S. Environmental Protection Agency, 2012, Drinking 

water contaminants—National primary drinking water 

regulations: U.S. Environmental Protection Agency, 

accessed December 5, 2012, at http://water.epa.gov/drink/

contaminants/index.cfm.

U.S. Environmental Protection Agency, 2013a, Hydraulic fracturing, accessed February 15, 2013, at http://water.epa.gov/

type/groundwater/uic/class2/hydraulicfracturing/.

U.S. Environmental Protection Agency, 2013b, Basic information about radionuclides in drinking water: U.S. Environmental Protection Agency, accessed March, 20, 2013, at 

http://water.epa.gov/drink/contaminants/basicinformation/

radionuclides.cfm. 

U.S. Geological Survey, 2009, 1-Arc second National Elevation Dataset: U.S. Geological Survey, SDE raster digital 

data, accessed February 15, 2013, at http://nationalmap.

gov/viewer.html.

U.S. Geological Survey, 2012a, National Water Quality Laboratory: U.S. Geological Survey, accessed December 5, 2012, 

at http://nwql.usgs.gov/.

U.S. Geological Survey, 2012b, Analytical procedures for 

dissolved gas: U.S. Geological Survey, accessed December 5, 2012, http://water.usgs.gov/lab/dissolved-gas/lab/

analytical_procedures/.

U.S. Geological Survey, 2012c, USGS water data for Pennsylvania: U.S. Geological Survey, accessed December 5, 2012, 

at http://waterdata.usgs.gov/pa/nwis/nwis.

U.S. Geological Survey, variously dated, National field manual for the collection of water-quality data: U.S. Geological 

Survey Techniques of Water-Resources Investigations, book 

9, chap. A1–A9, accessed December 5, 2012, at http://pubs.

water.usgs.gov/twri9A/.

For additional information:

Director

U.S. Geological Survey

Pennsylvania Water Science Center

215 Limekiln Road

New Cumberland, PA 17070

http://pa.water.usgs.gov/

Document prepared by the West Trenton Publishing Service Center
Sloto—Baseline Groundwater Quality from 20 Domestic Wells in Sullivan County, Pennsylvania, 2012—Scientific Investigations Report 2013–5085