We know from examples from Texas that injected wastewater can pressure up, making it more likely to move horizontally out in the formation. It could also move upward if there was a route to do so, such as uncased or inadequately cased abandoned wells, or an extensive vertical fracture system.

The Devonian Lower Huron Shale in Washington County, Ohio, is relatively shallow at 1900 to 2700 ft below sea level, putting it about half a mile below freshwater aquifers on average. The Lower Huron Member is the injection zone for several oil & gas wastewater injection wells that have migrated horizontally through the shale in a downdip direction, a few miles and up to 5 miles eastward.

There is evidence of pressurized fluid leaking up an abandoned well in Veto Lake when it “blew out” in 2021, and chemical tagging confirmed the injection wells as the source. David Jeffery, a professor at Marietta College, said, “Some of the fractures are letting the toxic fluids travel upwards.”

ODNR initially suspended injections at six of the seven nearby wells. Andy Chow said operations were stopped at four class II disposal injection wells, and a third‑party consultant will study private water wells. The division is working toward a plan to address the issues, but more injection wells should be scrutinized or shut down.