Commuters at a popular Medford parking garage near Wellington Station are out of luck after being told the soon-to-open Encore Boston Harbor casino is grabbing 700 spaces for its employees.

Kate O’Connell, who uses the Orange Line to get to work downtown, said she showed up Monday to find small signs stating that people like her with $105 monthly passes won’t be able to use them come July.

“It kind of leaves me stranded,” the 25-year-old from Medford told the Herald, noting that the garage is cheaper than most other local options. “I am still looking forward to the casino, but it’s going to add traffic and frustration to my commute.”

Pilgrim Parking, which runs the Station Landing Garage and others around Boston, didn’t respond to requests for comment.

Encore, which plans to open in Everett this month, will lease 700 spaces in that garage, Wynn Resorts spokesman Michael Weaver said, adding that the casino has 400 leased there already.

Wynn Resorts, which owns Encore, eventually will have 100 more spots in a different external garage or lot, as part of the casino empire’s signed agreement with the local cities is that it needs to have 800 parking spots off site for employees, Weaver said.

It’s a private garage, so the T has nothing to do with its operations, T spokesman Joe Pesaturo said, noting that the MBTA Wellington lot has monthly passes available and is not full.

Emily Paone, a legal assistant who lives in Everett, called the loss of spaces to the casino a “low blow.”

“I was supportive of the casino. Now I’m (angry),” said Paone. “This is not fair to commuters. How else are we going to get to the trains? It would have been nice for them to give notice to residents of surrounding cities. Now I’ll have to leave my car at home and take a bus and a train.”

Jennifer Boynton, 47, an insurance broker who commutes from her Woburn home to her job in Boston, said long-time clients will feel the pain more.

“What about the rest of the people who’ve been coming here for forever and a day?” she said, adding the loss comes as the MBTA is scheduled to raise fares.

“It’s going to impact a lot of people,” Boynton said, adding that she’ll have to take her company up on its offer to let her work from home twice a week, an option she noted most people don’t have.

Utsab Gurung, who commutes from Malden to his job as a cook at the Intercontinental Hotel in Boston, said he, his wife and his daughter all park at the garage.

“If we don’t get a chance to park here, it will be a problem for us,” said Gurung, 45. “I have no idea where we’ll park. There are no public parking spaces on the street.”

Clauder Aspilaire, who lives in Medford and works as a program coordinator at Simmons College in Boston, said not being able to park at the garage will be “super inconvenient.”

“They should have given proper notice; I didn’t know about this until you told me,” she told a Herald reporter. “They’re leaving hundreds of people stranded.”