CHARLESTON, W.Va. (AP) — West Virginia officials have reiterated that the state’s drinking water remains safe following an Ohio train derailment that led to a toxic plume of chemicals being released.

Chemicals that leaked from the derailment are being monitored as they move down the Ohio River, but they are not affecting the supply of drinking water, officials said during a briefing Thursday.

“We have not had any reports of this substance entering the water supply in any of the affected areas and there are no water advisories being issued at this time,” said state Health Officer Matt Christensen.

About 50 train cars, including 10 carrying hazardous materials, derailed in a fiery crash Feb. 3 in East Palestine, Ohio. Vinyl chloride was later released into the air from five of those cars before crews ignited it to get rid of the highly flammable, toxic chemicals in a controlled way, creating a dark plume of smoke.

Residents from nearby neighborhoods in Ohio and Pennsylvania were evacuated because of health risks from the fumes, but have since been allowed to return.

Water samples were collected along the Ohio River on Wednesday from Ravenswood to Parkersburg, West Virginia. Parkersburg is about 170 miles (270 kilometers) southwest of East Palestine. The samples detected butyl acrylate — one of the chemicals from the derailment — at levels below 3 parts per billion, said Scott Mandirola, the deputy cabinet secretary for the West Virginia Department of Environmental Protection. Federal guidance for drinking water has limits of 560 parts per billion, Mandirola said.

DEP spokesperson Terry Fletcher said in an email that vinyl chloride is among the compounds being tested for and “no detectable levels have been identified.”

The leading edge of the chemical plume was estimated to be near Point Pleasant and the mouth of the Kanawha River. Mandirola said the influx of water from the Kanawha River should add at least a 25% additional dilution on top of the mitigating effects of Thursday’s rains. The plume is estimated to reach the Huntington area late Friday or early Saturday. Huntington is about 265 miles (426 kilometers) southwest of East Palestine.

“Thus far, there’s no danger to our drinking water,” West Virginia Gov. Jim Justice said.

As a precaution, a utility company on Wednesday temporarily switched its water drinking source for the Huntington area to the Guyandotte River after installing pumping equipment and above-ground water lines.

Officials also said that air monitoring stations in the Northern Panhandle haven’t detected problems with air quality from the derailment.