UPPER EAST SIDE — When a crowded and growing school district like the Upper East Side has new classroom space open up, it’s a big deal.
A long and heated debate Wednesday night over the future of P.S. 158, at York Avenue and East 77th Street, proves the point.
Many parents want a middle school to move into P.S 158’s building when P.S. 267 moves out of the shared space and into its permanent home this September.
Parents — who are already fighting over whether the would-be school should be for gifted and talented students — will likely unite against the Department of Education if officials decide to put another elementary school there, or if a charter school is eyeing the space.
Eva Moskowitz is planning to open two new Success Academies in District 2, but a spokeswoman said it was “highly unlikely” either would be on the Upper East Side.
The space at P.S. 158 will not be available for a new school until the fall of 2013, Elizabeth Rose, of the DOE, said during a presentation Wednesday at a Community Education Council District 2 meeting.
The building’s upper floors are being replaced this summer, making it difficult for a new program to start there this fall. The delay will give the community more time to discuss what it wants, Rose added.
"I’m not making any specific proposals. I’m not making any recommendations," Rose said. "This is the first of what will be many dialogues before a decision or a consensus is made."
When the new school does open, it will have enough room for a small elementary school with two sections or a small middle school with up to four sections.
Parents from P.S. 77, or Lower Lab as the small gifted and talented school is called, have been clamoring for the space to expand their specialized program into a middle school. The school’s principal, Mara Koetke, said the new school would have 50 seats for the school’s current elementary school children and 80 for other District 2 students.
"It will start out with a reputation and a leader," Alan Cohen, co-president of Lower Lab’s PTA, said of expanding the school.
But parents with children at several local elementary schools said they were opposed to the idea that many students would be able to coast into these gifted-and-talented seats without open enrollment. They also blasted the idea of basing middle school admission on a test taken as a 4-year-old.
One parent of a P.S. 158 third- and fifth-grader blasted Lower Lab’s proposal as "a flawed, elitist, self-serving discriminatory program" that "would put the needs of  students ahead" of the community.
Rose presented data showing that the area will likely need more elementary school seats than middle school seats. There were 724 kindergarteners enrolled in neighborhood schools in 2011. That number is expected to grow to nearly 850 in the next five years, perhaps as soon as 2014, she said.
"Some time between 2014 and 2016, we will need more kindergarten seats," Rose said.
Meanwhile, District 2's middle schools are not at capacity, she said, noting that 2011’s enrollment of 6,548 students was below the 7,806 available seats.
Even with the projected increase from the ever-expanding ranks of elementary students, Rose believes the middle schools will have room since new middle schools — in other neighborhoods — will be opening in District 2.
Upper East Side parents, however, have said they want more middle school options close to home so their kids can walk to school. The CEC, a volunteer panel of parents whose role is advisory, agreed the building should be used for a middle school. But the panel voted down a resolution to move Lower Lab into P.S. 158, pending more discussion on the proposal.
Andy Lachman, of Parent Leaders of Upper East Side Schools, also agreed the space should be used for a middle school, but suggested it should be reserved for underperforming students.
"Why doesn’t an underperforming student deserve to get into a small school where a principal knows his name?" Lachman asked. "The pressure we’re putting on our kids is really sad."