The District's Spingarn Senior High School was designated a historic landmark Thursday, putting into question the start date of the city's streetcar line and potentially limiting the scope of the school system's plans for the site in coming years.

The DC Historic Preservation Review Board added the 60-year-old school to its list of historic sites after a request from the Kingman Park Civic Association, which has opposed plans for a trolley barn on the Northeast D.C. campus off Benning Road. That means the board gets to review any proposed changes to the site to make sure the work done to the school's exterior or its surrounding grounds is compatible with the building's character.

The designation likely means another delay for the city's streetcar system because the trolley barn is needed first to store and maintain the cars. DC Public Schools could be limited in making substantial changes to the site for future projects, including a planned vocational school there.

The H Street-Benning Road streetcar line was most recently slated to begin in late 2013, after facing years of delays. But the city shied away Thursday from setting any start dates for the car barn construction or the subsequent operation of the streetcars.

"We really just cannot speculate right now because we don't know how long the process if going to take," District Department of Transportation spokeswoman Dara Ward said after the decision. "Much of it is going to depend on how quickly we can get the Historic Preservation Review Board to sign off on the design."

The District's car barn plans already have been shown to the historic preservation office. "We think the design needs some work," said David Maloney, the state historic preservation officer.

The earliest the review board could view any revised plans would be late next month, but Ward said she isn't sure if the plans will be ready then.

Meanwhile, DCPS officials announced earlier this month that they want to close Spingarn and reopen it in a few years as a career and technical education school whose students could be trained at the car barn's proposed training facility. The interior of the school probably could be updated without review, but changes to the existing exterior that require building permits -- or any new construction -- would need approval.

DCPS spokeswoman Melissa Salmanowitz noted that the historic designation will be a factor in what happens in coming weeks but may not have major implications immediately as the vocational plan is not concrete. "The specifics of what that would look like is not squared away," she said.

But Maloney notes that the new historic designation is not a roadblock. It is designed to preserve the site but also make sure that it continues to be adapted for modern uses.

"We're not saying, 'No, no, no, don't change anything,' " Maloney said. "Just make sure you maintain compatibility with the character of the site."

Examiner Staff Writer Lisa Gartner contributed to this report.