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 Ohio Environmental Protection Agency is conducting a criminal investigation into how drilling wastes got into a storm sewer in Youngstown and drained into the Mahoning River.
The agency is "very concerned" by the discovery of dumping — possibly illegal — discovered late last week, EPA spokesman Chris Abbruzzese said in a statement the agency released Monday.
The problem was discovered near 2761 Salt Springs Road at the D&L Energy Group.
Since Thursday, state responders have directed the containment and cleanup of the discharged wastes from a storm drain, a tributary and the Mahoning River, Abbruzzese said.
Containment booms, absorbent pads, vacuum trucks and other equipment are in place and work continues to clean out the storm drain and remove any remaining product from the tributary, he said.
It was unclear how much waste might have been dumped into the storm sewer that then fouled the river, the EPA said.
The Youngstown Vindicator reported that at least 20,000 gallons of suspected fracking waste was involved.
Abbruzzese said the investigation, done in cooperation with the Ohio Department of Natural Resources, was in its preliminary stages.
The two state agencies will "pursue flagrant violations of the laws of Ohio to the fullest extent possible," he said.
D&L Energy is the company that owns and operates the injection well west of Youngstown that was blamed for a dozen earthquakes in 2011 in the Youngstown area.
D&L was not involved in the alleged illegal dumping and that other companies operating on the site are responsible, company spokesman Vince Bevacqua told the Youngstown Vindicator.