The amount of a suspected carcinogen in the pond at Heavenly Waters Park in Bel Air has dropped below a dangerous level, but county officials say they still won't let people fish there for a while longer.
County administrators fenced the pond and banned people from using it in June after test results showed the water contained small amounts of trichloroethylene, or TCE, believed to have come from a nearby landfill. The county kept the park itself open because administrators said that posed no public health threat.
"The levels of TCE are lower now, but I want to wait for the results of several more tests before I remove the security fence," said William T. Baker Jr., director of Harford's Department of Public Works. "I'm being overly cautious."
In June, the water in the pond contained six parts per billion of TCE, slightly more than the maximum five parts per billion of TCE the federal Environmental Protection Agency allows in drinking water.
Although the EPA does not limit the amount of TCE raw water may contain and still be considered safe, the county ordered the pond fenced and explored ways to clean it.
DPW employees then installed an aeration system to clean the water. TCE -- once widely used in paint, paint thinner, degreasing agents, surgical anesthetic and in making freeze-dried coffee -- evaporates when exposed to air because it does not bond with water.
Since the aeration system has been in place, the level of TCE in the pond has dropped to two parts per billion.
But the aeration process, which had been operated by a generator, has been temporarily discontinued until a permanent electrical source is installed near the pond, Mr. Baker said. Once a permanent power generator is in place, the aeration system will operate continuously.
Mr. Baker said he believes the TCE that contaminated the pond migrated through ground water from the now-closed Tollgate Landfill, across the street from the park.
The landfill, off Tollgate Road west of Bel Air, was operated first by the town of Bel Air, then by the county, as a central dump between 1954 until 1987, when it closed.