The Upper East Side is one step closer to getting a new and unpopular neighbor: a garbage storage site.

Opponents of the facility were dealt a severe blow yesterday when a state Supreme Court justice ruled that the Bloomberg administration could open the garbage storage site, which will be located at 91st Street and the East River, near the mayor’s ceremonial mansion.

The site has been a flashpoint since Mayor Bloomberg unveiled a proposal two years ago to change the way the 50,000 tons of garbage generated a day are carted out of the city.

The 20-year plan — which has been the source of heated debate because of the racial and socioeconomic overtones involved in the placement of trash transfer stations — calls for greater reliance on barge and rail than on trucks before the trash is dumped in landfills outside the city. It also forces each borough to deal with its own trash.

Judge Michael Stallman rejected all of the arguments made by the Gracie Point Community Council, the Association for Community Reform Now, and several other groups, which said putting the facility in the middle of a residential neighborhood is a health hazard that will increase pollution and truck traffic.

In his decision Mr. Stallman said the plan would “further the city’s announced, rational goals of promoting equity among the boroughs for responsibility over waste disposal, and reducing truck traffic.”

While the number of trucks passing through the Upper East Side site will increase, traffic in Harlem and Washington Heights to the north will be relieved of the soot-spewing vehicles because the need to truck to New Jersey will be eliminated.

The plaintiffs in the case immediately pledged to appeal the decision, which they said had several “errors of law.”

They reiterated claims yesterday that the environmental review by the city’s Department of Sanitation was flawed and that the Bloomberg administration did not adequately consider other options.

City Council Member Jessica Lappin, a Democrat who represents the Upper East Side, stood by her opposition to the project.

“It’s not appropriate to build a waste transfer station in the heart of a residential neighborhood and they were unwilling to look at other alternatives,” Ms. Lappin. “You are talking about a couple of hundred feet from where people live and from where tens of thousands of public school kids play.”

The president of the Gracie Point Community Council, Anthony Ard, said “the court made several errors of law.”

“The health and safety of the residents of one neighborhood are no less important than the healthy and safety of the residents of any other neighborhood,” Mr. Ard said last night in a telephone interview. “This is the only transfer station to be located in a densely populated neighborhood.”

The council approved the plan in July with the minority members lobbying for it because of it promised to shift the burden of trash disposal away from their communities. Council Member Charles Barron, who represents East New York, one of the poorest sections of the city, applauded the court decision and said the outer boroughs have carried the burden of the city’s trash disposal for too long.

“It’s time for them to do their fair share,” Mr. Barron said, referring to Manhattan residents. “Environmental racism must cease,” he said. “This is a move in that direction.”

The City’s Department of Law, which has been arguing the case since it was filed in October 2005, treated yesterday’s decision as a decisive victory. Mr. Bloomberg’s goal is to have the site, which for 40 years until 1999 was in use, reconstructed and expanded by 2009.

The mayor proposed the Solid Waste Management Plan in 2004, three years after the closure of Fresh Kills landfill on Staten Island. The loss of that facility without a real backup plan threw the city’s trash disposal system into disarray.

But the plan was stymied when the former council speaker, Gifford Miller, blocked it while running a campaign to unseat Mr. Bloomberg as mayor. The two men are neighbors in the Upper East Side district where the facility is located.

Two other proposed sites on Manhattan’s West Side — one on Gansevoort Street and the other at the 59th Street Pier — still face obstacles, but are not currently being litigated.