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 has told New York that state regulators should set limits of radioactive materials in gas-drilling waste water sent to public sewage treatment plants.
That should be done before the state allows any hydraulic fracturing or fracking of natural gas well in New York.
New York has not allowed any drilling into the Marcellus shale under a three-year moratorium, but the state is considering lifting that ban.
The EPA submitted its suggestion to the Department of Environmental Conservation on Wednesday night, the last day for comment on the proposal.
The federal agency also wants New York to develop a map of gas wells and to update it at least monthly to provide more information on drilling activities to the public.