Prepared in cooperation with the U.S. Department of Energy

Water Resources and Shale Gas/Oil Production in the 

Appalachian Basin—Critical Issues and Evolving Developments

Printed on recycled paper

Introduction

Unconventional natural gas and oil resources in the United 

States are important components of a national energy program. 

While the Nation seeks greater energy independence and 

greener sources of energy, Federal agencies with environmental 

responsibilities, state and local regulators and water-resource 

agencies, and citizens throughout areas of unconventional 

shale gas development have concerns about the environmental 

effects of high volume hydraulic fracturing (HVHF), including 

those in the Appalachian Basin in the northeastern United 

States (fig. 1). Environmental concerns posing critical 

challenges include the availability and use of surface water and 

groundwater for hydraulic fracturing; the migration of stray 

gas and potential effects on overlying aquifers; the potential 

for flowback, formation fluids, and other wastes to contaminate 

surface water and groundwater; and the effects from drill pads, 

roads, and pipeline infrastructure on land disturbance in small 

watersheds and headwater streams (U.S. Government Printing 

Office, 2012). Federal, state, regional and local agencies, along 

with the gas industry, are striving to use the best science and 

technology to develop these unconventional resources in an 

environmentally safe manner.

Water intake and water-level monitoring station for surface-water withdrawal at Fall Brook Creek, Ward Township, Tioga County, Pennsylvania. 

(Photograph courtesy of Dennis Risser, USGS)

U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2013–1137

August 2013
2

¢ 0

0

100 200 MILES

100 200 KILOMETERS

Marcellus Shale—

United States Extent 

Utica Shale—

United States Extent

EXPLANATION

Figure 1. Map showing extent of the Marcellus Shale and Utica Shale in the 

Appalachian Basin in the northeastern United States. 

Some of these concerns were addressed in U.S. Geological 

Survey (USGS) Fact Sheet 2009–3032 (Soeder and Kappel, 

2009) about potential critical effects on water resources 

associated with the development of gas extraction from the 

Marcellus Shale of the Hamilton Group (Ver Straeten and 

others, 1994). Since that time, (1) the extraction process has 

evolved, (2) environmental awareness related to high-volume 

hydraulic fracturing process has increased, (3) state regulations 

concerning gas well drilling have been modified, and (4) the 

practices used by industry to obtain, transport, recover, treat, 

recycle, and ultimately dispose of the spent fluids and solid 

waste materials have evolved. 

This report updates and expands on Fact Sheet 2009–3032 

and presents new information regarding selected aspects of 

unconventional shale gas development in the Appalachian Basin 

(primarily Virginia, West Virginia, Maryland, Pennsylvania, 

Ohio, and New York). This document was prepared by the 

USGS, in cooperation with the U.S. Department of Energy, and 

reviews the evolving technical advances and scientific studies 

made in the Appalachian Basin between 2009 and the present 

(2013), addressing past and current issues for oil and gas 

development in the region.

Water Supply

Hydraulic fracturing of Appalachian Basin shales uses 

about 3 to 5 million gallons of water per horizontal well (King, 

2012). Anecdotal information from drillers and the Susquehanna 

River Basin Commission indicates that approximately 

10 percent of all HVHF water used is recovered from the 

drilled and fractured formation in northeastern Pennsylvania 

(Susquehanna River Basin Commission, 2013). Any water 

remaining downhole is considered to be a consumptive loss and 

is no longer part of the hydrologic cycle.

Sustainable water-supply practices for HVHF include the 

continual but low-rate (relative to streamflow) withdrawal of 

water from streams to onsite holding tanks or impoundments 

(fig. 2). This practice is designed to allow for adequate 

downstream flow for aquatic ecosystems and downstream water 

users. Permit requirements that prohibit water withdrawals 

during low-streamflow (drought) conditions have resulted 

in minimal additional stream and (or) groundwater impacts 

in Pennsylvania where intensive hydraulic fracturing has 

recently taken place (Pennsylvania Environmental Digest, 

2010). Permitting of stream and groundwater withdrawals by 

state and regional agencies has proven to be an effective tool 

in mitigating the effects of HVHF water use during drought 

conditions. Consumptive loss of water over many decades 

by conventional or unconventional oil and gas development, 

among other consumptive uses, has yet to be quantified.

The gas industry has found that non-potable water sources 

may suffice in the HVHF process, at least in Appalachian Basin 

shales. The current best-management practice also recycles 

much of the flowback water into the next batch of HVHF fluid 

after treatment to remove suspended solids, thus reducing the 

amount of freshwater needed for drilling and hydraulically 

fracturing the next well. Non-potable water sources such as 

wastewater-treatment-plant effluent have been successfully 

used for HVHF with proper chemical treatment, and the 

Commonwealth of Pennsylvania has encouraged a study of 

mine wastewaters for such use (Pennsylvania Department of 

Environmental Protection, 2012).
A

B

C

(Photographs courtesy of the Susquehanna River Basin Commission)

3

Figure 2. A, Holding-tank facility; B, filling of the lagoon using tanker trucks; and C, a freshwater holding lagoon. 
4

Potential Effects on Drinking Water

The U.S. Environmental Protection Agency 

(USEPA) is conducting a study on the potential 

impacts of hydraulic fracturing on drinking-water 

resources. Because of the increasing development 

of gas and oil resources in the United States and 

comments received from stakeholders during 

development of the Plan to Study the Potential 

Impacts of Hydraulic Fracturing on Drinking Water 

Resources (U.S. Environmental Protection Agency, 

2011), the scope of the research includes the full 

life cycle of water used in the hydraulic fracturing 

process, from acquisition of the water through the 

mixing of chemicals and well stimulation to the 

management of flowback and produced water and 

their ultimate treatment and disposal. The USEPA 

study is collecting and analyzing new and existing 

data to evaluate possible impacts to both surface 

water and groundwater (fig. 3). The data are provided 

by nine hydraulic fracturing service companies 

and nine well operators, and are found in publiclyavailable databases to better understand the products 

and chemicals used in hydraulic fracturing fluids, 

accidental releases of chemicals, well practices, 

water use, and wastewater treatment and disposal. 

Laboratory studies are being conducted to develop 

analytical methods for chemicals known to be used in 

hydraulic fracturing fluids and assess the treatability of 

hydraulic fracturing wastewaters. Case studies provide 

new information on potential impacts at existing 

well sites, and computer modeling estimates the 

conditions needed for possible groundwater impacts 

to occur during generalized well scenarios. The 

USEPA research team is working in consultation with 

other Federal agencies, state and interstate regulatory 

agencies, industry, non-governmental organizations, 

and others in the private and public sector. In 

December 2012, USEPA published a progress report 

(U.S. Environmental Protection Agency, 2012a) 

describing the research projects underway as part 

of the study and the progress made as of September 

2012. The study plan and progress report are available 

on USEPA’s website (http://www.epa.gov/hfstudy).

Figure 3. Research activities and objectives from the 2012 U.S. 

Environmental Protection Agency’s progress report (table 8, p. 24).

Activity Objective

Analysis of existing 

data

Gather and summarize existing data from 

various sources to provide current information 

on hydraulic fracturing activities; includes 

information requested of hydraulic fracturing 

service companies and oil and gas operators.

Scenario evaluations Use computer modeling to assess the potential 

for hydraulic fracturing to impact drinking 

water resources.

Laboratory studies Conduct targeted experiments to test and develop 

analytical detection methods and to study the 

fate and transport of selected chemicals during 

wastewater treatment and discharge to surface 

water.

Toxicity assessment Identify chemicals used in hydraulic fracturing 

fluids or reported to be in hydraulic fracturing 

wastewater and compile available chemical, 

physical, and toxicological properties.

Case studies

Retrospective Study sites with reported contamination to 

understand the underlying causes and potential 

impacts to drinking water resources.

Prospective Develop understanding of hydraulic fracturing 

processes and their potential impacts on 

drinking water resources.

The recent (2011–13) slowdown in natural gas drilling 

resulting from low natural gas prices has reduced the demands 

for water withdrawals for natural gas drilling in Pennsylvania. If 

this diminished gas well development rate continues, the use of 

water resources for HVHF likely will decrease in the short term. 

The need to address water-resource issues remains, however. 

The current slowdown will increase the total duration for HVHF 

water consumption because it leads to a longer time frame for 

the full development of the oil/gas resource in the Appalachian 

Basin. The longer time frame necessitates development of 

effective management strategies for the region’s water resources 

in light of the increasingly variable climate.

Stray Gas

When methane gas appears where it is not wanted it is 

called stray gas. Incidents of stray gas occurrences in freshwater 

aquifers, specifically the presence of methane in water wells, 

have been documented during shale-gas development in 

localized areas of northern Pennsylvania (Osborn and others, 

2011; Jackson and others, 2013). The likely mechanism for 

the occurrence of stray gas in areas of active gas development 

is leaky cement seals that do not effectively isolate freshwater 

aquifers from shallow gas zones penetrated by the gas well 

(Bruffato and others, 2003). Determination of cause and effect 

for incidents of stray gas migration is not straightforward 
5

(Photograph courtesy of Matthew Conheady (www.nyfalls.com))

Figure 4. Natural gas seep at Chestnut Ridge County Park, Eternal 

Flame Falls, Erie County, New York. 

(fig. 4), especially without local background information 

(Ground Water Protection Council, 2012). Thermogenic 

(geologically derived) methane is known to occur naturally 

throughout the Upper Devonian strata overlying the Marcellus 

Shale, including the fractured rocks that serve as aquifers used 

for drinking water (Molofsky and others, 2011). Samples from 

water wells overlying oil and gas bearing formations commonly 

show the presence of methane gas, perhaps from multiple 

sources, even in areas that have not yet been drilled (Molofsky 

and others, 2013; Mulder, 2012; Kappel and Nystrom, 2012). In 

2011, in recognition of the threat to public health and safety as 

well as the environment, the Commonwealth of Pennsylvania 

revised the regulations concerning the design, installation, and 

cementing of surface and intermediate casings to help minimize 

gas migration and protect water supplies (The Pennsylvania 

Bulletin, 2011).

Abandoned and orphaned wells are another environmental 

resource concern related to stray gas. The number of abandoned 

wells ranges in the tens to hundreds of thousands in various 

states, and generally, only a small percentage of these wells 

have been field located. Additional attention by state and 

Federal regulators is being given to characterization of the 

distribution and condition of abandoned wells that penetrate 

drinking-water aquifers and that may be another avenue 

for stray gas and groundwater migration (Texas Railroad 

Commission, 2000; U.S. Geological Survey, 2013). For 

instance, in June 2012, an abandoned gas well drilled in 

1932 erupted with water and methane related to the drilling 

of a nearby gas well in Union Township, Tioga County, 

Pennsylvania. (StateImpact Pennsylvania, 2012). This issue has 

been and will continue to be addressed by the gas industry and 

by the states regulating oil and gas development.

Radioactivity in Shale Waste

Radium (Ra) is a naturally occurring radioactive material 

(NORM) that is present as a component of the Marcellus 

Shale and is produced from the radioactive decay of high 

concentrations of uranium and thorium found naturally within 

black shales (Schmoker, 1981; Bank and others, 2010). 

Uranium is poorly soluble in water under the anoxic (oxygenpoor) conditions typical of black shales, but radium is readily 

dissolved and transported (Rowan and others, 2011; Szabo 

and others, 2012). Although two of the radium isotopes (223Ra 

and 224Ra) have short half-lives (a few days), the other two 

isotopes, 226Ra and 228Ra, have 1,622 and 5.75 year half-lives, 

respectively; if dispersed in the environment, these isotopes 

will persist for long periods of time. Chemically, radium 

behaves similarly to calcium (Ca), strontium (Sr), and barium 

(Ba). Radium can readily precipitate along with salts of Ca, Sr, 

and Ba in groundwater or produced brines having high total 

dissolved solids to form scale in or on drilling equipment (fig. 5) 

or in on-site storage tanks or brine pits. The scale precipitate 

is rich in radium, and that may emit radiation to those working 

near such equipment over time. The scale may eventually be 

removed from the pipe and then is added to the waste stream 

from drilling that must go to a landfill or can be dispersed to the 

local soil. Leachates from these materials may contain radium 

that may eventually reach the local water table or run off to the 

local watershed.

The concentrations of NORM present in black shale 

drill cuttings, drilling mud, scale and sludge build-ups, fluids 

from spills, treatment residuals, and other waste products 

may be greater than background environmental levels. 

Disposal of these waste products on-site or in landfill burial 

Figure 5. Barium sulfate scale in drilling pipe. Radium can readily 

precipitate with these barium salts and may emit radiation to those 

working near such equipment, and may be potentially released to 

the environment if improperly disposed. 

 [Photo courtesy of Creative Commons.org. Scale bar at bottom in centimeters]
6

Radium in Groundwater

Data on radium distribution and occurrence in 

the freshwater aquifers of the Appalachian region 

are limited (Szabo and others, 2012), but median 

total (combined) radium activity in six samples of 

brine from oil and gas wells in western Pennsylvania 

was about 1,200 picocuries per liter (pCi/L) (Dresel 

and Rose, 2010). Radium (Ra) concentrations in 

Marcellus Shale fluids are distinctly higher than 

those from those brines—typically between 5,000 

and 15,000 pCi/L (Rowan and others, 2011). The 

high concentrations of Ra from the “produced 

water” (formation brines) can potentially exceed 

drinking-water standards even after treatment and 

dilution with fresh water. Radium dispersed to 

soils, sludges, and sediments from the brines can 

undergo long-term low-level leaching into water 

bodies, but release can be accelerated with sudden 

changes in soil or water chemistry. The disposition 

of Ra-enriched waste fluids and solids in relation 

to drinking water supplies has yet to be quantified, 

but the health risk of radium ingestion, from any 

source, is associated with increased human cancer 

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

The health risk is proportional to the exposure 

as radium is readily stored in bone from where 

it emits radioactivity into bone and surrounding 

tissue. The Maximum Contaminant Level (MCL) in 

drinking water for combined radium isotopes 226Ra 

and 228Ra and the alpha particles emitted during 

radium decay is not to exceed 5 and 15 (pCi/L), 

respectively (U.S. Environmental Protection Agency, 

2000). The establishment of an MCL is based on 

the Maximum Contaminant Level Goal (MCLG), 

whereby EPA considers the risk to sensitive 

subpopulations (infants, children, the elderly, and 

those with compromised immune systems) of 

experiencing a variety of adverse health effects. 

Further information on these goals and levels can 

be found at http://water.epa.gov/lawsregs/rulesregs/

regulatingcontaminants/basicinformation.cfm.

sites will require assessments of both gamma radiation 

emissions and radionuclide concentrations in solids and liquids 

(U.S. Environmental Protection Agency, 2008). Dispersal 

of radium into soils may have several effects in addition to 

the potential increase in gamma radiation exposures and the 

potential for leaching into water resources. The 226Ra emits 

radon gas as a decay product; structures built on the soil that 

contains 226Ra-bearing waste may have high levels of indoorair radon that require monitoring due to this type of exposure. 

Plants may also take up the 226Ra from soil. Recently (2013), 

the Commonwealth of Pennsylvania has initiated a study of 

the radioactivity of the Marcellus Shale through all aspects of 

the gas drilling, extraction, and waste disposal (Pennsylvania 

Department of Environmental Protection, 2013).

Fluid Waste Treatment and Disposal

Flowback fluid is recovered following HVHF and during 

the initial stages of gas production in the first 2 to 3 weeks 

following HVHF; it consists mostly of the water and chemical 

additives which have been modified during the hydrofracturing 

process. The flowback fluid can be treated at the well and 

recycled for use in the next HVHF well (Maloney and 

Yoxtheimer, 2012). Eventually though, as dissolved salts and 

minerals accumulate, this recovered fluid must receive proper 

treatment, transportation, and disposal.

During the early development of the Marcellus Shale 

in 2008, local municipal wastewater-treatment plants in 

Pennsylvania were used to process these waste fluids (Soeder 

and Kappel, 2009). These plants were not designed to treat the 

complex chemistry of flowback fluids, especially the high total 

dissolved solids (TDS), halides, metals, chemical additives, 

organic compounds, and radiological materials produced during 

and following the HVHF process. Most of these dissolved 

materials can pass untreated through the wastewater plant 

and into the receiving water, creating water-quality problems 

downstream from the plant outfall (StateImpact Pennsylvania, 

2013). In 2010, the Commonwealth of Pennsylvania strongly 

requested that only advanced industrial wastewater-treatment 

facilities capable of handling the various types of flowback fluid 

be used (Indiana Gazette, 2011). The gas industry complied 

with this request, which in turn, caused many drillers to recycle 

flowback fluids to reduce disposal volumes and expenses.

The high-salinity formation fluids (Blauch and others, 

2009; Haluszczak and others, 2013) present an additional 

wastewater-treatment and disposal challenge (Lutz and others, 

2013). These formation waters, called brines, may contain 

relatively high concentrations of sodium, chloride, bromide, 

and other inorganic constituents, such as arsenic, barium, other 

heavy metals, and associated radionuclides that substantially 

exceed drinking-water standards (Lutz and others, 2013). When 

these materials are removed at advanced wastewater-treatment 

facilities, they create a concentrated solid waste (sludge 

residual) that requires special handling and disposal in properly 

designed and regulated landfills. The radiological constituents 

pose problems even for the advanced treatment facilities, and 

any residual wastes that are created may have gamma radiation 

emissions greater than background levels (U.S. Environmental 

Protection Agency, 2008).

Deep Well Injection of Fluid Waste

The cost of disposal of residual waste from hydraulic 

fracturing operations using deep-well injection to underground 

injection control (UIC) wells compared favorably to advanced 

wastewater-treatment costs. UIC wells have been used for 

hydraulic fracturing wastewater disposal for conventional and 

unconventional oil and gas development across the United 

States. These UIC wells are regulated by some states and the 

USEPA and have been an important means of waste disposal for 

many years (U.S. Environmental Protection Agency, 2012b). 

The disposal formations are generally deep, saline aquifers 

below drinking-water aquifers and in some cases below gas/

oil-producing horizons. Unfortunately, the geologic formations 

capable of accepting these fluids are limited in Pennsylvania 

and New York (Pennsylvania State Extension, 2011; McCurdy, 
2011). Wastewater from many shale gas wells in Pennsylvania 

is transported to UIC wells in Ohio and Kentucky for disposal; 

these UIC wells at present have the capacity to accept wastes.

Induced seismicity can occur when fluids are injected into 

deep bedrock formations penetrated by the UIC wells, where 

they may lubricate pre-existing geologic faults and cause the 

faults to slip, creating small earthquakes. Although most UIC 

wells have been used successfully over many decades, a number 

of earthquakes occurred near Youngstown, Ohio, in 2012 as a 

result of shale flowback fluid disposal into a new, deep-injection 

well (Ohio Department of Natural Resources, 2012). A similar 

situation occurred in Arkansas from UIC wells used for disposal 

of residual wastewater from Fayetteville Shale wells (Horton, 

2012). UIC well operators, state regulatory agencies, and the 

USEPA have been re-evaluating the capacity of these disposal 

wells to handle wastes in a manner that will avoid induced 

seismic activity in the future.

Solid Waste Disposal

Horizontal drilling of black shales creates long boreholes 

within the organic-rich layers and generates hundreds of tons 

of drill cuttings (Maloney and Yoxtheimer, 2012). Black shales 

like the Marcellus Shale contain reduced sulfide minerals that 

can oxidize when exposed to air and rainwater, producing 

acidic, metals-rich leachate. The oxidized forms of some of 

these metals from the minerals are much more water-soluble 

and thus more mobile than in the original reduced state, 

especially under acidic conditions. Drill cuttings in West 

Virginia are typically disposed of on-site by burial in the mud 

pit (West Virginia Department of Environmental Protection, 

2010). In Pennsylvania, it has been observed that the drill 

cuttings are mixed with wood chips/sawdust or absorbent 

polymer to reduce water content (fig. 6) and then are taken 

to secured landfills or are reprocessed for other uses (Drilling 

Waste Management Information System, 2013).

The potential for oxidation and leaching of radionuclides 

and toxic metals associated with organic matter in black shale 

cuttings led to a preliminary assessment of the geochemistry of 

a number of black shales by U.S. Department of Energy (DOE) 

in 2010. The results of this initial study indicate that black 

shales like the Marcellus Shale contain minor, but detectable, 

amounts of heavy metals and other elements that can be 

detrimental to the environment if mobilized and concentrated 

in the soil or shallow groundwater (Soeder, 2011; Fortson and 

others, 2011). The results of the Soeder (2011) study were 

inconclusive but did indicate that additional analyses are needed 

to better define the fate and transport of leachate from black 

shale cuttings and evaluate the potential environmental hazards. 

Additional research by DOE is currently underway (Dan 

Soeder, DOE, written commun., February 2013).

Figure 6. Mixing of drill cuttings with absorbent polymer prior to shipping and disposal in a secured landfill. 

7
(Photograph courtesy of Curtis Schreffler, USGS)

Pipeline construction in the Endless Mountain region near Trout Run, Pennsylvania. 

Construction and Transportation

Hydraulic fracturing operations in the Appalachian Basin 

involve moving large amounts of heavy equipment, trucks, 

supplies, storage tanks, and fluids into mostly rural areas. 

Transporting all this materiel to and from drill sites has caused 

damage to some of the rural, steep, two-lane Appalachian 

Mountain roads. Many of the roads have been repaved or totally 

rebuilt by the gas drilling industry (Marcellus Shale Coalition, 

2011). Such intensive construction may result in considerable 

land and wildlife disturbance within small watersheds (U.S. 

Fish and Wildlife Service, 2013; Intermountain Oil and Gas 

BMP Project, 2013). The gas drilling industry has recently 

adopted practices to help reduce truck traffic, 

including the transport of freshwater by pipeline 

(fig. 7) and the reuse of flowback water. Local 

governments have worked with the gas industry 

to implement management practices to reduce 

well-pad construction and transportation impacts 

(Marcellus Shale Coalition, 2012).

Some of the management practices include 

keeping trucks off roads during specific times and 

finding alternate routes to well pads on roads that 

can accommodate heavy equipment. The road 

restrictions are accomplished through road-use 

agreements with the municipalities (Pennsylvania 

State University, 2012). However, even with 

agreements between the gas companies and state 

regulators, some local environmental impacts 

might occur (Slonecker and others, 2012; Drohan 

and others, 2012); therefore, regulatory agencies 

and the gas industry continue to support research 

to improve management practices Figure 7. Pipeline construction in northeastern Pennsylvania.

Summary

Unconventional natural gas and oil resources 

in the United States are important components of 

a national energy program that seeks both greater 

energy independence and greener sources of energy. 

Unconventional high volume hydraulic fracturing 

(HVHF) shale gas and oil development in the 

Marcellus Shale and Utica Shale is underway in 

the Appalachian Basin within Pennsylvania, West 

Virginia, and eastern Ohio and is proposed in 

New York, Maryland and Virginia. Compared to 

conventional gas production, the scale of shale gas 

operations may be much larger and has the potential 

to create significantly greater effects on landscapes, 

watersheds, water supplies, and water quality. Because 

of the potential effects, some states (New York and 

Maryland as of spring 2013) have placed moratoriums 

on development until these issues are resolved. At the 

same time, development of the shale gas resource is 

considered a major component of America’s energy 

supplies for the foreseeable future. 

Although the technology for directional 

or horizontally drilled wells used in combination with 

sophisticated hydraulic fracturing processes to extract gas 

resources has improved over the past few decades, the 

knowledge of how this extraction might affect water resources 

has not kept pace. Federal and state water-resource and 

regulatory agencies, the gas industry, and citizens desire a better 

understanding of the potential environmental effects from the 

hydraulic fracturing process. Advancements in the science 

can provide that understanding and lead to the development 

of best-management strategies for limiting adverse effects 

of shale gas development in the Appalachian Basin, as well 

as improvements in monitoring strategies designed to insure 

environmental quality.

8

By William M. Kappel, John H. Williams, and Zoltan Szabo
9

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11

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Fault in Upper Devonian bedrock near Towanda, Bradford County, Pennsylvania. 

Three well heads on a drilling pad, the closest well head being prepared for 

hydraulic fracturing.

Completed well pad with brine holding tanks (green) with nearby wind turbines 

near Gleason, Tioga County, Pennsylvania. 

Typical well drilling tower with associated equipment.

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