CHARLESTON, W.Va. (AP) — A notice ordering residents of a northern West Virginia community not to use their tap water entered its fourth week Wednesday after a treatment-plant malfunction allowed the release of a hazardous solvent.

Dr. Matt Christiansen, the state’s health officer, said preliminary findings from the U.S. Environmental Protection Agency showed tetrachloroethylene in the water serving the community of Paden City along the Ohio River.

Tetrachloroethylene is a harmful chemical widely used by dry cleaners. Paden City officials have said a dry cleaner in the town of about 2,500 residents closed early this century.

The city issued the “do not use” order on Aug. 16 after a pump valve malfunctioned at a water treatment plant. City officials said the issue was fixed then while testing on the water continued.

Christiansen said the order will remain in effect “until there’s no doubt in our minds that the chemical has been fully flushed from the system. In the meantime, we understand everyone’s frustration at the local level and concern with the situation. But our goal remains getting that water back on and doing it safely.”

Last year, the EPA added Paden City’s groundwater to a national Superfund cleanup priority list. Sites are added to the list when contamination poses significant human health and environmental risks. They are then eligible to receive federal funding for long-term cleanup projects.

At the time, untreated groundwater collected in Paden City was discovered to contain tetrachloroethylene at levels higher than the federally allowed limit, the EPA said. The agency says tetrachloroethylene is a likely carcinogen and can harm an individual’s nervous system, liver, kidneys and reproductive system.

Tetrachloroethylene had been detected in Paden City’s water system since around 2010 at levels below maximum allowable standards The city was assessed a violation notice in December 2018 after the levels exceeded the federally allowed limit.

Paden City’s new water treatment plant debuted in May 2020.

“This is an EPA Superfund site, and they’re the lead agency,” Gov. Jim Justice said Wednesday. “Sometimes federal agencies move a lot slower than what we want to move.”