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.
West Virginia is overhauling its regulations on natural gas-oil drillinjg, and a number of groups are pushing to eliminate centralized pits to store liquids and flowback waters.
Such pits "pose an unnecessary risk to human health and the environment, no matter how well designed or constructed," said the West Virginia Environmental Council.
There are safer alternatives to storage pits, the group says.
Similar comments came from the grass-roots West Virginia Surface Owners Rights Organization.
April 12 was the cutoff date for comments to the West Virginia Office of Oil and Gas.