Boston public high school enrollment is on the slide, leaving nearly 3,000 seats empty and raising questions about possible school closures.
The problem is expected to accelerate as the school system faces intensifying competition from charter schools, which are adding 1,500 seats over the next few years, according to a School Department memo last month that was obtained by the Globe.
A handful of schools, such as Another Course to College in Brighton and the English High School in Jamaica Plain, are operating in buildings less than half full.
At the Jeremiah Burke High School in Dorchester, a $50 million renovation five years ago that included a new gymnasium, performing arts center, and cafeteria has done little to entice students to enroll, and more than half of the seats are empty.
Some School Committee members and government watchdogs say the excess capacity represents excess spending.
“It’s a misuse of public funds to have empty seats,” said Meg Campbell, a School Committee member who also runs the Codman Academy Charter School. “Every dime we are spending on a classroom not being fully used is a dime we are not spending on programs that benefit students. We don’t have unlimited dollars.”
With 17,376 students attending high school this year, enrollment is nearly 2,000 students lower than in 2005 and is at its lowest level since the late 1990s.
Boston’s high school enrollment drop mirrors a recent statewide trend of fewer teenagers, largely caused by the ending of a baby boomlet.
The demographic shift compounds perennial challenges for the Boston school system, which often sees families leave the city before high school. The charter school expansion adds a new wrinkle and will result in a smaller portion of Boston students enrolling in the city’s school system.
Schools with low MCAS scores, such as the Burke and English, tend to be hardest hit. But there are exceptions. Another Course to College, for instance, is in a building that it once shared with another high school, which relocated this year to a different site.
Maintaining the 2,945 empty high school seats carries a hefty price tag: an estimated $8.4 million this year. The School Department, using a formula based largely on teacher salaries and average class sizes to generate a ballpark figure, estimates each empty seat costs $2,857.
Yet the School Department has no plans to close or consolidate schools. It is pushing forward with plans to spend millions of dollars to add hundreds of seats at several high schools.
Superintendent Carol R. Johnson, who is retiring this month, said the School Department is examining building space, as it puts together a five-year capital plan for this fall. She declined to discuss any recommendations that might be included. “It would be premature for us to say what will happen,” Johnson said.
She defended the school expansions, saying they have waiting lists and the School Department needs seats for dropouts who reenroll.
Almost half of the city’s 33 high schools have occupancy rates below 90 percent. Burke and English could accommodate 1,200 students each, but both have fewer than 600 students, according to School Department figures.
On the other end of the spectrum, the city’s flagship, Boston Latin School, is completely full, as well as six other high schools.
Michael O’Neill, the School Committee chairman, said some excess capacity is necessary to accommodate enrollment shifts, but he added, “there is a fine line between what is the right amount of excess capacity.”
The shrinking high school population is in sharp contrast to rising enrollment in preschool and early elementary-school grades that has the city scouring for space for an additional 1,000 students this fall.
That hunt for classrooms has prompted Johnson to propose reopening the former Higginson Elementary School building this fall, sparking a heated School Committee debate about the best use of high school buildings.
Campbell pointed out at a committee meeting on June 19 the Burke and a few other high schools have room for another school. Fellow committee member Mary Tamer agreed, urging officials to tighten up space.
“We are going to have to think creatively,” Tamer said in an interview. “We are going to have to look at every possibility, including the possibility of closing or the possibility of merging schools. I don’t think anything should be off the table at this time.”
The excess capacity came to light after a June 4 City Council hearing, where questions were raised about City Councilor Charles Yancey’s proposal to build a high school in Mattapan.
Johnson shot down the idea in a memo to the council’s Ways and Means Committee, writing “even as we increase enrollment in the early grades, the expansion of high school charter seats means we will continue to have excess capacity in our high schools for many years to come.
“At this time, we do not believe that an investment in a new high school space would be an appropriate use of public dollars — rather we believe resources could be better applied upgrading and enhancing our existing facilities,” she wrote.
The declining enrollment could create problems as the city seeks millions of dollars from the state to replace the highly enrolled Quincy Upper School in Bay Village and the under-enrolled Dearborn Middle School in Roxbury, which wants to add a high school.
Last week, the Massachusetts School Building Authority sent a letter to the School Department questioning the effect declining enrollment could have on those two proposals and other projects.
Johnson has struggled to address dropping enrollment. She abandoned plans to close three high schools in 2008 after students, parents, and teachers protested, and kept one open and merged the other two.
Then in 2010 Johnson won School Committee approval to shut down two high schools at the Hyde Park complex and to merge six other high schools elsewhere into three.
But a year later, the committee — at Johnson’s urging — voted to reopen Hyde Park and a few other facilities, in part to expand some popular high schools and after the school building authority threatened to end reimbursements on renovation projects at those sites.
Samuel Tyler, president of the Boston Municipal Research Bureau, a government watchdog funded by businesses and nonprofits, said he supports expanding high-performing high schools, but other schools must close. “The issue of reducing excess capacity — consolidating or closing schools — is a tough process,” Tyler said, “but they can’t continue to shy away from that.”James Vaznis can be reached at email@example.com. Follow him on Twitter @globevaznis.