Chesapeake Energy Corp,the Oklahoma-based firm is the No. 1 driller in Ohio.
Rig Count Interactive Map by Baker Hughes, an energy services company.
Shale Sheet Fracking, a Youngstown Vindicator blog.
The Ohio Environmental Council, a statewide eco-group based in Columbus.
Earthjustice, a national eco-group.
People's Oil and Gas Collaborative-Ohio, a grass-roots group in Northeast Ohio.
Concerned Citizens of Medina County, a grass-roots group.
No Frack Ohio, a Columbus-based grass-roots group.
Fracking: Gas Drilling's Environmental Threat by ProPublica, an online journalism site.
Pipeline, blog from Pittsburgh Post-Gazette on Marcellus shale drilling.
Allegheny Front, environmental public radio for Western Pennsylvania.
On June 8, Platts reported that federal researchers are looking into whether hydraulic fracturing or fracking fluids can travel thousands of feet via geologic faults into drinking water aquifers.
The study is being done by the U.S. Department of Energy.
A fault from the Marcellus shale could provide "a quick pathway for fracking fluids to migrate upwards," said Richard Hammack, a spokesman for DOE's National Energy Technology Laboratory.
The experiment is being conducted in Greene County in southwest Pennsylvania where conventional shallow wells were drilled and then capped many years ago.
Drillers in the Marcellus shale are now active in Greene County.
The industry has long maintained that such migration does not occur.