NGA ISSUE BRIEF: Marcellus Shale & Appalachian Production


  • Major shale gas basin located in Appalachian region (WV, OH, PA, NY)
  • Largest shale-producing region in the U.S.
  • Provides supply security and cost competitiveness for high-priced Northeast region
  • Responsible environmental management a key element of successful development
  • NGA: production can yield multiple benefits: increased supply; source diversity; improved air quality; proximity to high-demand, high-cost demand market; local and state tax revenues; jobs

Source: PA DEP, 5-14

The Appalachian region is the largest natural gas production area in the United States, and the Marcellus Shale basin is the largest source of that regional production. The Northeast, long accustomed to being "at the end of the pipeline," now finds itself located next to - and indeed on top of - one of the largest natural gas basins in the U.S.


This shale gas formation extends from West Virginia into Ohio, Pennsylvania and New York.
As shown in the map, its geographic area (around 95,000 square miles) is quite large, leading to great expectations for the ultimate size of the economically recoverable resource base. In a July 2011 report, the U.S. Energy information Administration (EIA) reported the share of Marcellus acreage by state as follows: Pennsylvania, 35.35%; West Virginia, 21.33%; New York, 20.06%; Ohio, 18.19%; Virginia, 3.85%; and Maryland, 1.09%.

Appalachian Production

The Marcellus/Appalachian Shale region is the largest shale gas producing region in the U.S. - and is estimated to have the largest resource base. Output as of early 2023 has grown to nearly 35 Bcf/d.
U.S. EIA observed in March 2023 that "In 2022, the Appalachia region in the Northeast produced more natural gas than any other U.S. region, accounting for 29% of U.S. gross natural gas withdrawals (or 34.6 Bcf/d)."
Annual production in Pennsylvania alone has grown from 0.6 trillion cubic feet (Tcf) in 2010 to 7.48 Tcf in 2022. Pennsylvania is the second largest gas producing state in the U.S., after Texas.
While Appalachia remains the largest producing region in the U.S., future growth is being constrained by the lack of new pipeline capacity to "take away" more supply to U.S. domestic markets. EIA noted in March 2023: "Even as Appalachia remained the most prolific U.S. natural gas-producing region, its production growth has been slowing because sufficient pipeline takeaway capacity is not available to transport more natural gas. No new major pipeline capacity additions from the Northeast came online in 2022. In 2021, gross natural gas withdrawals in the Appalachia region had grown by 1.4 Bcf/d. In 2022, growth was just 0.1 Bcf/d, less than in 2020, when the COVID-19 pandemic and subsequent mitigation efforts limited production growth."

Chart: U.S. EIA, 3-28-2023

Managing Environmental Issues

Environmental issues associated with unconventional gas production are multiple but manageable. The issues include infrastructure development, land and water access, air emissions, and water treatment (water is one of the key ingredients in the hydraulic fracturing process used to dislodge the gas from the shale rock formations). Responsible production is not only achievable but essential.
The MIT study on natural gas from June 2011 notes that "the environmental impacts of shale development are challenging but manageable." State and federal agencies have regulatory oversight, with state environmental agencies holding primary responsibility over the drilling process. Industry has the responsibility to ensure that the entire process is conducted in an environmentally safe manner, and to follow "best practices."
In an April 2009 report entitled "Modern Shale Gas Development in the United States: A Primer," issued by the U.S. Department of Energy (DOE), the following was noted:
Photo source: PA PUC

"The primary differences between modern shale gas development and conventional natural gas development are the extensive uses of horizontal drilling and high-volume hydraulic fracturing. The use of hydraulic drilling has not introduced any new environmental concerns. [emphasis added] In fact, the reduced number of horizontal wells needed coupled with the ability to drill multiple wells from a single pad has significantly reduced surface disturbances and associated impacts to wildlife, dust, noise, and traffic...Hydraulic fracturing has been a key technology in making shale gas an affordable addition to the Nation's energy supply, and the technology has proved to be an effective stimulation technique. While some challenges exist with water availability and water management, innovative regional solutions are emerging that allow shale gas development to continue while ensuring that the water needs of other users are not affected and that surface and ground water quality is protected. Taken together, state and federal requirements along with the technologies and practices developed by industry serve to reduce environmental impacts from shale gas operations." (p. ES-5).

For Further Information

Pennsylvania Dept. of Environmental Protection Marcellus Shale page

NGA Issues Brief: Natural Gas & the Environment

U.S. EPA web page on hydraulic fracturing

U.S. EIA's "Drilling Productivity Report," released monthly