Charles County officials headed off a potential confrontation over elevated levels of radiation in a subdivision's water supply with their decision last week against discharging the polonium-tainted water into a nearby stream.

In March, residents of the 95-home Chapel Point Woods subdivision learned that the county planned to install a reverse osmosis filtration system to remove naturally occurring polonium and radium from their water supply. The level of radiation coming from three wells is about three times the federal limit.

But the question then became: Once the radiation is removed, where should it go?

The county initially wanted to dump a daily dose of 8,600 gallons and the radioactive materials into a small stream that runs through the subdivision before emptying into the Port Tobacco River. Some residents and members of the Port Tobacco River Conservancy adamantly opposed the idea because they feared the highly toxic polonium could be dangerous to children playing in the stream and to fish and other aquatic life.

But at a meeting with residents Tuesday night, officials said the county had decided not to release the substances into a tributary of Wills Branch. The county will cancel its discharge permit application with the Maryland Department of the Environment, said Jerome Michael, the county's director of public utilities.

The change of heart came after a preliminary study by the Department of the Environment found that the concentrations of polonium estimated in the discharge water -- 225 picocuries per liter -- would exceed safe levels, Michael said. State officials at a public meeting in La Plata on Tuesday night said they would not release the study until it was approved or specify what the safe levels of polonium are.

"With the numbers they were talking about," Michael said, "we're not even close. Not even close."

Some of those gathered in La Plata found the news reassuring.

"This was a good decision," said David Gardiner, the executive director of the Port Tobacco River Conservancy. "There have been concerns by several people that the level of polonium would be a very serious problem if it were released into the stream."

The county must now find an alternative method of disposing of the polonium. Michael said one possibility would be to truck the discharge water to the Mattawoman Wastewater Treatment Plant off Hawthorne Road near Mason Springs. It would be a more expensive option, he said, but when diluted by the 15 million gallons of daily discharge at the plant, the radioactive substances probably would not cause a problem in the Potomac River.

Installation of the Chapel Point Woods filtration system is scheduled for completion in the summer, and the timeline will not be affected by changing the discharge plans, officials said. A test of the system removed 97 percent of the polonium from the water, said Ben Movahed, an engineer with Watek Engineering Corp., which is designing the filter.

In the late 1990s, hundreds of wells in Anne Arundel County were found to have elevated levels of radium, an element that occurs in trace amounts in rocks and soil. But this case was the first discovery of polonium in Maryland.

"This isn't something we've come across in Maryland before," said Steve Luckman of the permits division of the Maryland Department of the Environment.

Officials did not know why the polonium was in the earth below these three wells, which descend about 600 feet into the Patapsco aquifer. No other nearby wells outside the subdivision have had elevated radiation levels, officials said. Residents of Chapel Point Woods, weary of buying bottled water for drinking and cooking, want to be able to say the same soon.

"As long as they proceed with treating the water," said Bruce McCormick, who has lived in the neighborhood for 14 years. "That's what matters to me."

Allan and Terri Hungerford of the Chapel Point Woods subdivision check out a water filter in February. Charles County must find a way to dispose of polonium removed from area water.