Residents filled the Berkeley City Council Chambers to voice their concerns about the relocation of the Downtown Berkeley post office during a public meeting Thursday.

The U.S. Postal Service expressed interest in relocating its 97-year-old Downtown Berkeley branch to help offset declining revenues from a decrease in first-class mail and the increased costs of a 2006 congressional mandate to prefund retiree health benefits.

First-class mail volume is down 25 percent from its 2006 peak, according to the Postal Service’s “Plan to Profitability” presentation.

“When you lose that much volume, a lot of revenue goes with it,” said Augustine Ruiz, Postal Service spokesperson.

The plan to relocate the branch at Allston Way was proposed in June, as the current 57,000-square-foot location is too big for the Postal Service’s needs. Under the plan, retail services would be moved to a yet-to-be-determined location of about 4,000 square feet, and postal carriers would be moved to a nearby annex. There would be no service interruptions to postal customers, Ruiz said.

“It would be unfortunate if it closed, and we don’t know what it would be used for if it were sold,” said Councilmember Jesse Arreguin.

Arreguin said that he plans to propose other options for the use of the building to the Postal Service, including partly leasing the building, allocating the front of the building for post office retail space and having another tenant use the rest of the building.

“Is it really cost savings to sell a building you own and lease a building you don’t own?” Arreguin said.

“This is an amazing legacy that was paid for by our parents and grandparents,” said Harvey Smith, part of the Committee to Save the Berkeley Main Post Office. “It’s stripping part of our national heritage.”

Ruiz noted that whatever happens to the building — which is on the National Register of Historic Places — it must adhere to the proper historical requirements.

The date of the next public meeting has yet to be determined and will be preceded by a 15-day advance notice. After the meeting, the public will have an additional 15-day comment period before recommendations are sent to Postal Service offices in Washington, D.C. After the comment period, Postal Service representatives in Washington will make the final decision about the relocation. There will be a 15-day appeal period following the decision.

Still, Ruiz said that this will not be a hasty decision.

“We need to make sure we do our due diligence,” he said.