W.Pa. forests being fragmented by natural gas drilling
A U.S. Geological Survey study of Butler and surrounding counties found thousands of acres of land and forest disturbance because of Marcellus shale and traditional gas well drilling.
The USGS study examined aerial images from the National Agriculture Imagery Program taken between 2004 and 2010.
In Butler County, 109 natural gas extraction sites resulted in more than 324 acres of disturbance, including about 13 miles of new roads, according to the most recently released study.
The disturbance was concentrated in the northeastern portion of the county.
That's compared to 647 natural gas sites, with more than 1,300 acres of disturbance and 140 miles of new roads in Allegheny County. In Washington County, there were 949 sites that resulted in more than 4,400 acres of disturbance and about 172 miles of new roads, according to USGS studies.
The studies draw no conclusions regarding the forest disturbance.
“It is to allow people to know what's around their own home,” said Lesley Milheim, a physical scientist and co-author of the ongoing series of 11 studies. “We are just documenting what we find. We hope that people who are interested in these types of things will take a look at it to see if it's causing any changes.”
The researchers defined disturbance as distinct events that disrupt ecosystem structure and function and change resource availability and the physical environment.
Jason Bell, a member of Marcellus Outreach Butler, a group that is concerned about the health and environmental impacts of Marcellus shale drilling, said the information is “a wake-up call.”
“Often we don't get a bird's-eye view of what's happening,” he said. “It's easy to see one or two wells and think it's having isolated effects.
“It's one more example of why we need to carefully monitor this, instead of allowing it to happen free-range.”
The USGS study also examined forest fragmentation, which occurs when large areas of forest are altered into smaller, “less functional” habitat areas.
The smaller sections reduce the amount of “central forest,” which is preferable to many species because it's the inner-most part of the forest, according to the study.
In Butler County, the number of forest patches increased by 36 because of Marcellus site development.
The patch sizes were reduced by a total of 1.5 acres.
Forest fragmentation was more significant in Allegheny and Washington counties, where forest was reduced by a total of 2.47 acres and 18.5 acres, respectively.
The state Department of Environmental Protection is the regulatory agency for natural resource extraction, but the state Department of Conservation and Natural Resources tracks forest fragmentation.
The DCNR works to balance the extraction of resources with preserving forest for animal habitat, said department spokeswoman Christina Novak.
“Our approach is to avoid impacts wherever that is possible, minimize them as much as we can (and) remedy them to the greatest extent possible,” she said. “Where we own the subsurface rights and have leased state forest land, we are very intentional in requiring companies to make use of existing infrastructure — such as roads and pipelines — to reduce forest fragmentation.”
Novak said the DCNR's shale gas monitoring program tracks the number of acres converted for natural gas development as well as forest fragmentation. The department's first report on forest fragmentation is in the draft stages, she said.
Bell said he's hopeful the USGS will continue to monitor disturbance from gas drilling.
“This is a great snapshot of what can happen, but it doesn't show what is happening and what's going to happen,” Bell said.
Since 2010, the last year included in the study, more than 400 wells have been permitted in Butler County, he noted.
Milheim said it's unknown whether the USGS will do followup studies.
“It's always in our thoughts to come back, but we don't know if that will happen,” she said.
Jodi Weigand is a staff writer for Trib Total Media. She can be reached at 724-226-4702 or firstname.lastname@example.org.