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Measuring Landscape Disturbance of Gas Exploration in Eight Pennsylvania Counties
Released: 10/22/2014 10:36:57 AM

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U.S. Department of the Interior, U.S. Geological Survey
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12201 Sunrise Valley Dr, MS 119
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Lesley Milheim 1-click interview
Phone: 703-648-7230

Hannah Hamilton 1-click interview
Phone: 703-648-4356

Landscape change in Pennsylvania's Cameron, Clarion, Elk, Forest, Jefferson, McKean, Potter, and Warren counties resulting from construction of well pads, new roads and pipelines for natural gas and coalbed methane development is being documented to help determine the potential consequences for ecosystems and wildlife, according to a new U.S. Geological Survey report.

Using geospatial data and high resolution aerial imagery from 2004-2010, USGS researchers documented spatially explicit patterns of disturbance, or land use, related to natural gas resource development, such as hydraulic fracturing, particularly disturbance patterns related to well pads, roads and pipeline construction.

Spatially explicit data on the level of landscape disturbance -- which is geographic information systems data, mapped to a high degree of spatial accuracy -- is critically important to the long-term study of the potential impacts of natural gas development on human and ecological health.

Through programs such as the National Land Cover Database, and Land Cover Trends, USGS has a long record of studying the consequences of land-use and land-cover changes. The current level of natural gas development in much of the country, and its effects on the landscape, is an important contemporary land-use/land-cover issue.

"Landscape disturbance effects have consequences for the ecosystems, wildlife, and human populations that are collocated with natural gas extraction activities. This study examines the landscape consequences of gas extraction for eight counties in Pennsylvania; and is the final publication in the series that documents landscape disturbance in the Marcellus Shale region of the state," said Lesley Milheim, lead author of the study.

Data from this report will be used to assess the effects of disturbance and land-cover change on wildlife, water quality, invasive species and socioeconomic impacts, among other investigations.

Landscape Changes by County


Number of Gas and Oil  Extraction Sites

Hectares (acres) Disturbance

Kilometers (miles) of New Roads

Kilometers (miles) of New Pipelines



70.1 (173.2)

3.3 (2.0)




553.5 (1367.7)

185.3 (115.1)

14.7 (9.1)



397.9 (983.2)

210.5 (130.7)

4.8 (2.9)



618.1 (1527.3)

287 (178.3)

8.7 (5.4)



872.1 (2155.0)

316.8 (196.8)

19.6  (12.1)



1320.3 (3262.5)

507.8 (315.5)

41 (25.4)



356.9 (881.9)

74.1 (46.0)

80.8 (50.2)



501.5 (1239.2)

248.3 (154.2)

1.2 (0.7)

Of the 10,442 sites, 166 sites were Marcellus shale sites, 3,848 non-Marcellus shale sites, 5,358 oil sites, 1,461 other infrastructure sites, and 96 pipeline segments. Marcellus shale sites were dispersed across all eight counties with the majority of sites located in Elk (37 sites), McKean (31 sites), and Potter (26 sites) counties.

Non-Marcellus shale natural gas sites were concentrated in southern Clarion (703 sites) and Jefferson (988 sites) counties, with dense clusters in McKean (566 sites), Warren (255 sites), and Forest (339 sites) counties. 

Other infrastructure sites were dispersed across all eight counties with a majority of sites in Jefferson (317 sites) and McKean (423 sites) counties. The majority of oil sites occurred in dense clusters in northwestern Elk (296 sites), Forest (955 sites), western McKean (2,609 sites), and southeastern Warren (1,196 sites) counties. In general, Marcellus shale sites (1.8 ha) are about six-times larger than non-Marcellus shale sites (0.3 ha), which are larger than oil sites (0.2 ha).

The study, Landscape Consequences of Natural Gas Extraction in Cameron, Clarion, Elk, Forest, Jefferson, McKean, Potter, and Warren Counties, Pennsylvania, 2004–2010, by L.E. Milheim, E.T. Slonecker, C.M. Roig-Silva, S.G. Winters, and J.R. Ballew, Open File Report 2014-1152, is the last of the series of reports relating to natural gas landscape disturbance in Pennsylvania, and is available online.

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