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.
The U.S. Environmental Protection Agency on Thursday announced that it will deliver drinking water to four households in the town of Dimock because of contaminated water from nearby drilling operations.
The agency also said it will conduct its own testing of drinking water in 61 homes in rural Susquehanna County.
The state of Pennsylvania last December allowed a company drilling in the Marcellus shale to half water deliveries.
Three years ago, the state Department of Environmental Protection blamed drilling by Cabot Oil & Gas Corp. for contaminating 19 drinking water wells in Dimock. The company has denied polluting the wells