A U.S. District Court judge last week ordered a halt to a major Metro construction cleanup that residents of Friendship Heights said would aggravate the pollution of nearby Little Falls Branch.

Judge June L. Greene told Washington Metropolitan Transit Authority officials to suspend until Friday plans to scrape accumulated concrete from drains that serve the subway track area. Residents contend that the scraping would result in massive amounts of fine dust and particulate that would choke off life in the stream.

The concrete built up in the drains during construction of the Metro tunnel under Wisconsin Avenue when excess concrete was washed away from the tracks and into the drains.

Attorneys for Metro and citizens' groups from Somerset and Friendship Heights are scheduled to appear Friday to argue whether the ban should be extended until the case is decided.

Greene's temporary restraining order is the latest turn in a suit by community members charging that Metro is polluting Little Falls Branch with debris draining from the tunnel and diesel fuel that has leaked from underground storage tanks at Metro's Western Avenue bus garage.

Metro officials have acknowledged losing an undetermined amount of diesel fuel from a leaky underground storage tank. They have replaced the tank, but area residents charge that the fuel continues to drain into the stream and has polluted the water table.

Frank R. Fileatreau, a Metro attorney, would not discuss details of the case, but said that although Metro officials are looking into other ways to clear the tunnel debris they have found no alternative to draining it into channels that lead to the stream.

After the citizens' groups filed suit in March, Metro officials installed an 8,400-cubic-foot settling tank designed to separate oil and sediment from water leaving the subway drains. Jeffrey G. Miller, an attorney for Somerset, said in court papers that the separator was "erratic" and had not stopped the pollution.

Miller said the stream is "covered with this white gunk that's smothering all life in the stream. . . . People can't use the stream."

The suit asks that Metro stop the alleged sediment and oil pollution and clean up residues in Little Falls Branch.

Somerset Mayor A. Eugene Miller noted that it was after the towns filed suit that Metro installed a water-cleaning chamber in the subway drains. "The fact that we ever had to go to court shows how recalcitrant [Metro officials] are," he said.