A New Bedford charter school’s request to start two new schools to educate nearly 1,200 students set off a firestorm in the city last year. Mayor Jon Mitchell vowed to block the expansion, afraid of the financial impact on the public school system. Charter supporters from around the region rallied behind Alma del Mar school.

The debate led to a compromise that could become the first significant cooperation between charters and traditional schools in years.

“I was delighted to see a long-standing vitriolic impasse seemingly broken in New Bedford,” said Paul Reville, a Harvard University education professor. “For too long, we’ve had this intense civil war in the education sector over charter schools. So I’m constantly on the lookout for ways we can find middle ground.”

The plan would allow Alma del Mar to set up a new school, but with 450 students, far fewer than originally requested. Instead of running a citywide lottery to enroll students, the new school would draw students from a neighborhood zone. In exchange, the school district would give a vacant building to the charter school at no cost. The deal depends on the legislature passing a measure allowing charter schools to operate neighborhood schools.

The compromise has plenty of detractors. Charter school supporters say children in New Bedford, where 66 percent of students graduate in four years, should get access to even more seats at Alma del Mar. Alma del Mar’s K-8 students consistently score above their peers in New Bedford public schools in math and English. Alma Del Mar leaders say there are hundreds of families on a wait list for seats at their existing school.

The president of the Massachusetts Teachers Association, Merrie Najimy, said that the deal is "unacceptable” because it will “drain much-needed funds" from the school district.

“We wish that state education officials would put half as much energy into supporting funding our district public schools as they put into finding new ways to force communities to accept — and pay for — privately run charter schools,” Najimy said in a statement shortly after the proposal was announced in January.

But New Bedford Superintendent Thomas Anderson said the deal “mitigates” the “hit” that would have come from the original proposal.

When students leave traditional school districts to attend charters, they take with them thousands of dollars in per-pupil state aid. The state has promised to reimburse districts for a limited time, but has shortchanged them in recent years. Alma del Mar’s initial request would have diverted around $15 million from New Bedford schools, according to Anderson.

“It was going to be a huge challenge for the city to raise funding for us if that was going to happen,” Anderson said.

The compromise plan with fewer seats limited to a neighborhood zone, by comparison, would cost around $4 million, according to Anderson.

“That’s how it is,” Anderson said. “This is an idea that’s going to work as well as we can make it work.”

Alma del Mar and New Bedford are still working out details of the agreement. If the deal falls apart, or if the legislature doesn’t pass necessary changes to state law allowing for the neighborhood zone, then Alma del Mar can add about 600 seats by a citywide lottery.

If the experiment does go forward, there could be another benefit to educators and students in Massachusetts. It could test one of the critiques about charter schools — that they achieve good results because they attract above-average parents.

“We should have a pretty good controlled experiment, between the performance of the charter school versus another comparable school in New Bedford,” Reville said.

Our coverage of K though 12 education is made possible with support from the Nellie Mae Education Foundation.