COLUMBUS -- A state investigation has concluded that a series of a dozen earthquakes in the Youngstown area in northeast Ohio was induced by a deep injection well disposing of wastewater that's a byproduct of hydraulic fracturing.

A preliminary report released by the Ohio Department of Natural Resources on Friday based the conclusion on "a number of coincidental circumstances." Factors included the opening of D&L Energy's well in December 2010, quakes being clustered around the well bore, a fault since identified in the bedrock, and evidence from monitoring.

The state will impose tough new brine disposal regulations as a result.

Future injection into Precambrian rock will be banned and state-of-the-art pressure and volume monitoring will be required. Electronic tracking systems will be required to identify chemicals in the fluids entering the state.

The operator the wellsays the state has based its findings on incomplete science.

D&L Energy noted in a statement Friday that the Ohio Department of Natural Resources came to its conclusions without testing the well. It says the well complied with all state regulations at the time it was idled by the company in January.

D&L said there is "no reason to rush and accept bad or incomplete science," since the well is closed.

By JULIE CARR SMYTH Associated Press