The special collection, which is kept in a room on the library's third floor, has been off-limits to the public since September because longtime curator Greg Laing is away from work due to a medical problem.
The trustees expect to reopen the collection within a few weeks, but an exact date has not been set, said Andrew Herlihy, the mayor's chief of staff.
"Their plan is to open the collection for 15 to 20 hours per week using a worker from a temporary agency that specializes in providing library science services," Herlihy said. "They welcome the use of volunteers, but they are still insisting on having a professional in charge, which is fine with us because we don't have to pay a temp benefits.
"We just want the room open as soon as possible," Herlihy said.
Interim Library Director Mary Johnson-Lally did not return phone calls for this story.
The mayor considers the special collection to be an important city tourist attraction, Herlihy said.
"People from all over the country come to Haverhill to use the special collection to research their family history," Herlihy said, adding that the library's temporary plan includes also finding a way to open the collection for a few hours each week in the evening and on weekends.
The special collection includes historical books and paintings, old city documents, century-old photographs, maps and artifacts. It is perhaps most popular among people tracing their roots in the area or researching old buildings and properties. The library is at 99 Main St., across from City Hall.
Mayor James Fiorentini and the trustees have been at odds over whether to open the room using volunteers. The mayor wants the library to accept the free help offered by several residents, including David Swartz, a local history buff and former city councilor.
Johnson-Lally and the trustees board have been adamant that they won't OK the use of volunteers without a staff person or library services professional to oversee the special collection.
At their meeting yesterday morning, Herlihy said, the trustees decided to hire a temporary worker from an agency that specializes in providing library science services. The trustees will use the same agency that recommended Johnson-Lally to the trustees about a year ago, called BiblioTemps, Herlihy said.