Westminster shut down one of its wells last month after testing by state environment officials found a cancer-causing compound.
Concentrations of ethylene dibromide that exceeded federal safety levels were found in public well No. 4 at the Westminster Air Business Center, said Thomas B. Beyard, Westminster director of planning and public works.
City officials voluntarily shut down the drinking water source Nov. 7 after being notified of the state's test results, Mr. Beyard said. The well is near Business Park North and Aileron Court.
Tests found ethylene dibromide in the well at a concentration level of .29 parts per billion. The federal Environmental Protection Agency has set the maximum drinking water standard for the contaminant at .05 parts per billion.
"The concentration exceeds the maximum levels, but it's extremely low," Mr. Beyard said.
The possibility that ethylene dibromide entered Westminster's drinking water supply at unsafe levels is very unlikely, he said.
The contaminated well water was pumped to the city's main distribution system and would have been diluted by other drinking water sources.
Mr. Beyard said the well accounted for only 3 percent of the county's water supply, and shutting it down will not cause a water shortage.
Tests conducted on nearby public and private wells showed no trace of the contaminant, he said.
Banned by the EPA as a pesticide in 1983, ethylene dibromide is used as an additive for leaded gasoline to prevent knocking noises in vehicle engines.
AExposure to the chemical at high levels over long periods of time has been shown to cause cancer in laboratory rats and mice.
The city of Westminster, working with the county and state environmental health officials, has begun an investigation to determine the source of the contamination.
"We'll keep the well out of service until the problem is rectified," Mr. Beyard said.
He said buried gas tanks are a possible source of contamination.
used to be an airfield, and fuel facilities were on site to supply aircraft.
Mr. Beyard said the contaminated well contained no benzene or other petroleum products generally found in motor fuel.
"That's what's really strange," he said. "It's got a lot of us spooked, and we're going to try to track it down."
As an amendment to the Safe Drinking Water Act of 1986, the EPA ordered that public drinking water sources be tested for ethylene dibromide and other contaminants that weren't previously regulated, said Quentin Banks, a spokesman for the state Department of the Environment.
The testing period began in January 1993 and concludes at the end of this month, Mr. Banks said.
Mr. Beyard urges anyone with information about possible sources of the well contamination to call 848-9002.