ExxonMobil Corp. abruptly closed its service station in Fallston yesterday under mounting pressure from residents, who blame seepage from the station for the contamination of their drinking water.

ExxonMobil said the move was a "business decision" based on the profitability of the station at Routes 152 and 165 west of Bel Air in Harford County. Business sagged recently because of nearby roadwork and publicity about the contamination, the company said.

"When we looked at the decline in business, the rationale for keeping it open was not there," Jim McDonald, ExxonMobil's dealer sales manager, said in a statement.

The station's closing is the latest development in what is believed to be the biggest incidence of well contamination in state history, with more than 225 residential wells containing traces of methyl tertiary butyl ether, or MTBE. The chemical, added to gasoline to make it burn more cleanly, has been linked to cancer in laboratory animals, though its toxicity to humans at low levels has never been determined.

The contamination has spawned two class action lawsuits and state legislation dealing with MTBE detection and public notification of contamination. The Maryland Department of the Environment, which is investigating the contamination in Fallston, said the closing of the station will not influence whether ExxonMobil is deemed responsible for a cleanup.

McDonald said the company reached a deal with operator-dealer Rick Hicks, who could not be reached for comment.

Upper Crossroads residents claimed a small victory.

"It was our perception that every gallon we pumped in our gas tanks up there put our drinking water at risk," said Tom Lusardi, one of many residents who refused to buy gasoline at the station.

"We've taken out the cause and the root of the problem," resident Gene Ratych added. "We're still left with a massive contamination."

Of the contaminated wells in Fallston, 11 had concentrations of MTBE above the state's "action" level, ExxonMobil said.

The company has acknowledged responsibility for up to half of the contaminated wells, but it says it needs to do more tests to determine the extent of its culpability. Its initial report on the contamination is under review by the Maryland Department of the Environment, which oversees chemical cleanups.

The environmental department said it had no role in ExxonMobil's decision to close the station. "MDE did not -- I repeat, did not -- order a closure," said department spokesman Richard McIntire. "They still are acting as a responsible party and have been very co- operative throughout this process."

The agency will hold a meeting Monday in Fallston. ExxonMobil will present its report to residents.

The company pledged to continue working with the state on a cleanup plan.

Closing the station "is something we had asked for in our original lawsuit," said Scott Shellenberger, an attorney with the firm of Peter G. Angelos, which filed one of the lawsuits. Both suits are pending in U.S. District Court in Baltimore.

"The fact that they're ripping the tanks out certainly speaks volumes about who's responsible for the MTBE leak in Fallston," Shellenberger said.

ExxonMobil maintains the decision to close the station has nothing to do with the lawsuits.

Jim White, a gas company consultant in California who has no ties to ExxonMobil, said the decision to close the station probably had nothing to do with the lawsuits.

"The closure of a station is nine times out of 10 because of economic reasons," said White, who has followed reports of the MTBE contamination in Fallston. "I just can't find any reason to question ExxonMobil's motives."

Yesterday, a crew began taking down the station's sign and removing Exxon logos. Exxon eventually will demolish the building and remove all equipment, including underground tanks and lines.

The company has no plans for the 1.43-acre site, ExxonMobil spokeswoman Betsy Eaton said. ExxonMobil bought the property in 1986 for $325,000, property records show.

McIntire said the future owner would be granted liability protections if ExxonMobil enrolls the site in the state's voluntary cleanup program.