Water gushed through a crack in the ceiling of a Morton Salt mine in Ohio last month, forcing the company to shut the facility down for good, according to the Guardian.
The closure eliminates 77 jobs in Fairport Harbor and threatens winter travel safety across the broader Great Lakes region, which relies on the subterranean salt reserves to clear snow and ice from roads.
Operating approximately 2,000ft (610 meters) beneath Lake Erie, the facility produced about 1.3 million tons of rock salt annually. The sudden halt leaves municipalities scrambling for supplies after heavier-than-average winter weather depleted regional stockpiles.
Trumbull County, situated 30 miles from the shuttered mine, relies entirely on the Fairport Harbor site for its road salt. “We get about 30,000 tons [of salt] a year from the mine. But we have a stockpile of around 14,000 tons,” Trumbull County engineer David DeChristofaro told the Guardian.
“We are waiting for the Ohio department of transportation. If necessary, we will mix salt with aggregate, one to one, as was typically done 15 years ago, to stretch our supply of salt. But that adds to cost because it needs to be swept up at the end of winter,” DeChristofaro said.
Underground Great Lakes risks
The incident has drawn scrutiny to five active salt mines operating partly or entirely beneath Great Lakes waterways in Ohio, Michigan, and Ontario. Morton Salt officials stated weeks after the emergency that they still cannot determine the exact source of the water intrusion.
Mining operations extract the salt through drilling and explosives. Decades of blasting combined with underground aquifers can alter subterranean rock stability, according to geological experts.
“Blasting can fracture rock near an excavation, and removing rock changes the stresses carried by the roof, pillars and surrounding layers. For water to enter, there must also be a connected pathway from a water source to the mine,” Xiong “Bill” Yu, a professor of engineering at Case Western Reserve University in Cleveland, told the Guardian.
Yu added that a nearby aquifer might supply water through a fault, connected fractures, or a compromised shaft or seal. He said that while 1,000 feet of rock provides meaningful separation, the primary engineering question involves the continuity of the barrier layers.
Historical water breaches
Similar underground water breaches have occurred at other major salt operations in North America over past decades. In 2017, the Cargill-run Whiskey Island salt mine located 30 miles west of Fairport Harbor experienced a water intrusion event that released hazardous levels of hydrogen sulfide gas. That facility extends 16 square miles beneath Lake Erie and produces up to 4 million tons annually.
Major historical failures include a 1994 incident where a Western New York salt mine flooded with aquifer water and collapsed. In 1980, Lake Peigneur in Louisiana drained entirely after an oil rig breached the roof of an underwater salt mine situated 1,300ft below the surface.
Federal oversight of US mines falls under the Mine Safety and Health Administration. The Biden administration previously placed a Morton Salt mine in Louisiana on a pattern-of-violations notice for compliance problems in December 2022, though authorities lifted that notice in April 2025.
Morton Salt and Cargill decline inquiries on mine safety
Morton Salt did not respond to inquiries regarding how frequently the Fairport Harbor mine underwent full perimeter inspections prior to closure, whether they identified the water source, or if they plan new safety measures at other locations. Cargill also did not respond to questions regarding safety steps at the Whiskey Island mine.
Local media and environmental advocates have questioned whether continued mining beneath Lake Erie poses long-term risks to regional drinking water. An editorial in the Cleveland Plain Dealer questioned if the rock roof could breach and create saline swamps in a lake that supplies drinking water to millions in the US and Canada.
Industry observers argue that independent regulatory oversight is now necessary to evaluate subterranean stability across the remaining lakebed mines. Yu advocated for a targeted review of water-intrusion risks.
“The [Morton mine] incident is reason to check how each mine detects and responds to unusual seepage, and to review the condition of shafts and seals, the stability of roofs and pillars, and any known pathways from water-bearing rock,” Yu told the Guardian.
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