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.
Drillers into Pennsylvania's Marcellus shale are recyling more and more of their briny, chemical-laden wastewater, but significant quantities of the salty bromides are getting into streams that provide drinking water.
In fact, in most cases, drillers are complying with a state request to keep the salty bromides from being discharged to streams.
The Associated Press analysis of state records indicates that 97 percent of shale wastewater was either recycled, sent to deep-injection wells in Ohio and elsewhere or to a treatment plant that doesn't discharge to streams.
Experts are puzzled as to why bromide levels remain high in Pennsylvania's streams.
Experts are now wondering if a regulatory loophole exists or if shale gas drillers are only part of the problem.
Bromides combined with chlorine used in water-treatment plants to create cancer-causing trihalomethanes.
Ohio laws prohibit the discharge of drilling wastes to streams. Such wastes must be injected deep underground.