"DRUG DEALERS are not going to be on the streets while I'm mayor."

-- Mayor Anthony Williams.

Yellow police tapes have been showing up on the streets of Petworth, Columbia Heights and the Parkview areas in Northwest Washington. Already familiar in several violence-drenched east-of-the-river neighborhoods, the tapes in Northwest D.C. also mark the scenes of fatal shootings, most tied together by a common enduring thread: drug dealing. Dealers are on the streets and doing business on the mayor's watch.

Despite a decline in major crime rates, drug-related violence remains a dangerous presence. It is diminishing the communities where the slayings take place. It threatens economic development, investment and tourism in a city that needs all three, and it tears at the fabric of the city's rich social and cultural life. Drug-related violence is a problem that city hall cannot talk away.

Residents harried by nightly shootings will settle for nothing short of getting drug sales and the dangers they entail removed from their neighborhoods. From Capitol Hill to Anacostia, Columbia Heights and Park View, the demand from residents shut in by open-air drug markets is to see more police on the streets -- now and constantly.

The police department's decision, announced on Tuesday, to extend the police summer mobile force beyond its original Sept. 30 termination date is a first step. Those special officers apparently have made a difference in some of the neighborhoods where they were assigned this summer. Keeping those officers on duty for an additional month and deploying them to other hot spots may provide protection for beleaguered communities. But law enforcement's task of regaining permanent control of the streets is neither an overnight job nor one to be left solely to the summer mobile force. Only more patrolling of neighborhoods by beat officers and a stronger police presence will convince drug dealers that the streets of Washington belong to the law-abiding and not to them. At the moment, Mr. Mayor, drug dealers don't believe it.