BILLINGS, Mont. — An estimated 5,000 gallons of a chemical used to deice roads spilled into the Clarks Fork River, killing dozens of fish, after a semitrailer crash Monday near the Montana-Wyoming border.
The Montana Department of Environmental Quality said two tankers being pulled by the semi and carrying magnesium chloride went into the river along Montana Highway 72, two miles north of the Wyoming border.
One of the tankers broke open, spilling its entire contents. The other tanker did not leak and was safely removed, the DEQ said.
Public water suppliers downstream of the crash site, including in Billings and Lockwood, were notified of the spill in case the chemical plume threatens drinking water systems. The Clarks Fork, a tributary of the Yellowstone River, flows north from Wyoming into Montana.
Dozens of dead fish were found near the crash site by emergency crews, authorities said.
Wildlife workers patrolled the banks of the river looking for additional damages. Officials also placed live fish in cages into the water near the spill site to see if they suffer any problems.
But Bob Gibson with Montana Fish, Wildlife and Parks says magnesium chloride is designed to dilute quickly, which could lessen environmental damage.
Exposure to magnesium chloride can cause people to suffer eye and respiratory irritation and vomiting, said Tom Livers with the Montana Department of Environmental Quality.
The river is relatively slow-moving, meaning water supply administrators should have time to close their intake valves if a plume of concentrated chemical approaches, Livers said.
The unidentified driver of the semitrailer, operated by Lynch Trucking of Riverton, Wyo., was cited for careless driving.
Montana Highway Patrol Trooper Gabriel Bernard said the driver failed to negotiate a turn as he approached a bridge over the Clarks Fork and crashed into the guardrail.
One of the trailers rolled down the embankment and into the river, and the other flipped over the guardrail and into the water, he said.