The Brookhaven Arts and Humanities Council had to leave its exhibit and office space -- called the Gallery on the Hill -- at the amphitheater, said director Mary Capasso.
"The Bald Hill venue was a beautiful venue," Capasso said. "Perhaps it didn't get the traffic that you would get on a main street. But we've been there 20 years."
The former gallery space is going to be used for a restaurant, town officials said.
After a goodbye party on May 7, the all-volunteer council moved to the Phoenix Gallery in downtown Bellport, which Capasso said is a tight squeeze. "For the time being, that's where we'll have to be," she said. "Hopefully we can rise from the ashes."
In a statement, town Supervisor Mark Lesko said the agreement reached in April with Ronkonkoma's JVC Broadcasting to run the amphitheater "includes the development of the Chalet into a restaurant, which necessitated the move."
He said the town will continue to display the council's artwork in Town Hall. "We wish them the best of luck at their new home in Bellport."
Capasso said the council will forge ahead with its mission, no matter the location. "We're like the little arts gallery that could," she said.
The amphitheater has operated more than $1.5 million in the red during the past four years. The five-year pact with JVC, which owns several Long Island radio stations, was designed to ease the burden on taxpayers. JVC will manage and promote the 7,000-capacity amphitheater and share revenue with the town.