D.C. Police Chief Isaac Fulwood Jr., stating that the annual Halloween celebration in Georgetown has brought dangerously large and unruly crowds in recent years, announced yesterday several steps to discourage people from gathering there this year.

Fulwood said police will not close Georgetown streets for revelers as they have for several years, will control the number of pedestrians entering some streets, and will arrest people with open beer containers.

In addition, fire officials will aggressively patrol Georgetown clubs and will force patrons out of any in which officials think the maximum occupancy has been surpassed, Fire Chief Ray Alfred said.

"It's just impossible to manage these crowds," Alfred said. "My worst fear is having a fire in that area . . . . It could take a long time before we could get any equipment on the scene."

"We want to unsanction the unsanctioned," Fulwood said of the yearly event, which has never been organized or promoted by city officials as it grew in size through the 1980s. "If you want to have Halloween, have it in your own neighborhood."

For several years, police have blocked traffic on Wisconsin Avenue and M Street NW on Halloween night to make way for pedestrians. Years ago, the great majority of the revelers wore costumes, but each year fewer people have dressed up, and the crowd has become younger.

Police in recent years also have reported a sense that the crowds were beyond their control. It has sometimes taken ambulances up to 45 minutes to pick up people in the middle of the crowd, authorities said.

The biggest crowd came in 1987, when 150,000 crammed into the historic district. Since then, officials have made increasingly emotional appeals that people not come, and in 1988 only 75,000 people came.

Last year the crowd fell even more, to 60,000. But in the early hours of the morning, as their numbers were dwindling, a brawl turned ugly and three men were stabbed, one fatally.

City officials are sending letters to Georgetown bar owners urging them not to advertise Halloween promotions, and to local university officials urging them to discourage students from coming, Fulwood said.

Fulwood's decision on the Halloween event grew out of long discussions with Georgetown business figures, especially since last May, when cutbacks in police details there caused a howl of outrage from residents and merchants. The cuts were quickly restored.

Georgetown merchants said they support city efforts to play down Halloween because they fear further violence could hurt the business atmosphere there. "We welcome people in Georgetown, just not so many on that night," said Paul Armato, executive director of the Georgetown Business and Professional Association.

Association President David Levy, owner of the Key Theater, said he is trying to persuade clubs not to sponsor special Halloween promotions, which he said are a selfish practice that hurt other Georgetown businesses.

But Paul Lukas, owner of the Winston's and Paul Mall clubs there, said no club has advertised a Halloween promotion for about seven years. Teenagers in the street, not bar patrons, are the problem, he said.

The move resembles the city's action on New Year's Eve parties at the Old Post Office building downtown in the last three years. Mayor Marion Barry had said in the mid-1980s that the event would one day rival New York's. But open alcohol drinking and rowdiness marred the event for several years, and a high school girl was strangled in 1986.