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.
National environmental groups on Friday called on the U.S. Environmental Protection Agency to ban the use of diesel in hydraulic fracking or fracking.
That action came after the agency had released a guidance for regulating the practice.
The eco-groups including the Sierra Club, Clean Water Action, the Natural Resources Defense Council, Earthjustice and Earthworks want the practice banned instead.
They call the use of diesel in the fracking process a harmful practice.
Diesel is currently used in the fracking process and poses serious risks to drinking water, the group say.
The EPA guidance is not enough to protect families from benzene and other toxic chemicals contaminating drinking water, they say..
A 2005 federal law exempts hydraulic fracturing from the Safe Drinking Water Act -- except when diesel is used.
The EPA is accepting public comment on its proposal for 60 days.
For more information, go to http://water.epa.gov/type/groundwater/uic/class2/hydrauicfracturing/hydraulic-fracturing.cfm.