The city-owned First Street Garage has a $50-per-month deal that lets locals get cars off the street during months in which there might be snow. (Photo: Google Maps)

Blame for overcharging at the city’s First Street Garage was taken Monday by Susan Clippinger, director of Traffic, Parking & Transportation.

“The problem occurred in the department, not with the vendor which operates the garage. We failed to get the information properly to them,” Clippinger said Monday while taking questions from the City Council. Her own department also failed to notice the error. “We do go over those reports, and the person handling those reports was the person I’d failed to communicate directly with to make sure they knew the change had been made, so they weren’t picking up on it.”

“There’s really no excuse for what happened and I apologize for that,” she said.

The 245 First St. garage is in East Cambridge, near the Lechmere T stop and the Cambridgeside Galleria mall.

Residents can park at the garage, operated for the city out of the Boston office of Standard Parking, for $50 per month from November through March, but nine residents paying by credit card were being charged double that amount. Councillor Tim Toomey, who brought forward the topic and questioned Clippinger, said he found out only because one resident left him a message full of “salty”language explaining he’d been offered a bargain rate of $50 — “and it wasn’t a cost savings, this is what they were entitled to from the beginning,” Toomey said.

“How could a mistake like this happen?” he asked, saying that with the economy as it is, and considering the program is intended to keep cars off the streets in case there’s snow, “this is, to me, unacceptable.”

He did, however, appreciate Clippinger taking responsibility and the city’s efforts to correct the situation.

The residents who were overcharged were offered either refunds or credit toward future parking fees, with the credit winning out, according to City Manager Robert W. Healy.

There aren’t similar deals offered at other city garages because they’re better used, Clippinger said, and her department didn’t want to risk having too many cars for too few spaces. The Green Street Garage, which was mentioned in the report filed with the council, is excluded “because it’s very well used now,” she said.

Councillor Ken Reeves, though, wondered how that could be so, since a primary reason the Green Street Garage filled so frequently was its use by police and their visitors up until 2009, when the department was freshly moved to 125 Sixth St. from Western Avenue and Green Street in Central Square. In a couple of years the building is to be filled with offices for the Cambridge Housing Authority, Multi-Service Center and Community Learning Center.

“I know it’s popular with the business community, etc., but a lot of people could not be parking there. I think the whole top floor, in fact, was police officers, so there must be another answer to that question … I wonder if you might revisit the conclusion you stated” about use of the Green Street Garage, Reeves said. “I’m sure that the census of who’s in that garage must be down significantly based on no police.”