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.
Chesapeake Energy Corp., the biggest leaseholder in Pennsylvania, was fined $565,000 on Thursday for environmental violations by Pennsylvania's Department of Environmental Protection.
The violations include hydraulic fracturing or fracking liquids that entered a local creek last April.
Chesapeake paid $190,000 for losing contro0l of a wellhead for four days in April while fracking in Bedford County, Bloomberg News reported.
Inspectors found elevated levels of total dissolved solids, chlorides and barium in the stream, the state said.
The other fines were for dirt at Chesapeake drilling sites entering local streams.
Chesapeake has leases on 1.78 million acres in Pennsylvania with its Marcellus shale. It is also the No. 1 player in Ohio's Utica shale with 1.35 million acres in leases.