Islanders are restless over upgrades to the Casco Bay Garage that will put the elevator and one of two stairwells out of commission for about five months.

Residents who park their cars in the garage at night and take the ferry home are concerned the closure will create a hardship for the elderly and other residents, who often have carts full of groceries and other provisions. Instead of using the elevator, those residents will have to walk up the stairs or use the traffic ramps.

“I’m concerned. What am I going to do if I park on the fourth floor?” said 74-year-old Peaks Island resident Emily Sherwood, who commutes daily from Peaks Island to visit her husband at a Portland rehabilitation facility. She said she often brings him supplies from home.

City officials will meet with residents at 4 p.m. Thursday in the conference room of Casco Bay Lines to address concerns about the project, which is scheduled to begin on Monday and last until Memorial Day.

City spokeswoman Jessica Grondin said there are about 300 monthly pass-holders who are islanders, but it’s unclear how many are year-round residents.

She said Peaks Island residents were first told about the project at an island meeting in November and the city’s parking division issued a notification last month.

The residents did not hear from the company that operates the garage, MHR Management, until Tuesday.

In a letter to pass-holders, the company said it was considering using two golf carts help people during rush hour periods and one golf cart during the day.

“It’s better than nothing,” said Timmi Sellers, a member of the Peaks Island Council.

“I don’t think that’s going to help mothers with baby carriages. We think more things will need to be done. I hope we can come to a good understanding tomorrow.”

Sellers believes there should be a supervised area for residents to leave their belongings while they park or retrieve their vehicles.

Sherwood agreed, noting that last summer she left her bag unattended for a few minutes and it was quickly confiscated by security.

MHR Management, which owns 51 percent of the garage while the city owns the rest, did not return several requests for comments. But in its letter to pass-holders, the company said both the elevator and stairwell projects are “inseparable” and one cannot remain in service while work is being done to the other.

Grondin said the $600,000 project, which is being funded by parking revenues, will take months because it involves the installation of important structural supports that were not put in when the garage was built about 25 years ago.

“They started to notice some cracking,” she said. “This is very necessary in order to not have anyone get hurt.”

During the construction, people with handicapped parking placards will be able to park on the main level, which is traditionally used by police and firefighters, who have a fire boat crew headquartered there. Public safety vehicles will be moved to another level.

Grondin said the city has received less than a dozen complaints from island residents, but Sellers said she expected a large turnout for Thursday’s meeting, due to the number of people impacted.

Adding to the frustration of islanders, Sellers said, is the fact that monthly rates increased in July from $130 a month to $140.

“We’re paying more for less and it’s taking too long,” she said.