Cumberland now owns what is supposed to be its first public beach, but the former owners are trying to block the town’s controversial, voter-approved plan in court.

A development company, 179 Foreside LLC, bought 104 acres of the Payson estate in Cumberland Foreside on Friday, then immediately sold 25 acres of prime woodland and Casco Bay waterfront to the town.

Voters decided in November to borrow $3 million to finance the deal. Following contentious local campaigns, the vote was 2,372 to 2,126, or 53 percent in favor.

Town officials hope to allow limited public access as early as Memorial Day, though the heirs of Marion Payson filed a lawsuit Thursday seeking to block public access to the beach.

“This is a great day for the town of Cumberland,” said Town Manager Bill Shane. “We’re very confident that we will prevail. This is a property we want to protect in perpetuity so many generations of Cumberland residents will be able to enjoy this magnificent site.”

The town’s portion of the Payson estate includes nine acres near Foreside Road, a half-mile right of way to the waterfront, and 14 acres of prime shorefront and tidal property with a nearly half-mile-long beach and a 220-foot-long pier.

On Thursday, the Payson heirs filed a lawsuit in Cumberland County Superior Court against the town and the Chebeague & Cumberland Land Trust. The heirs claim that both town officials and the trust are ignoring a conservation easement drawn up by their grandmother that doesn’t allow public access beyond walking trails in the woods.

“They were there when their grandmother drafted this easement in 1997,” said Scott Anderson, a partner at Verrill Dana, a Portland law firm.

Anderson said the easement allows the developers to build a 10-lot subdivision, but it prevents the town’s plan to allow public access to the beach, with an improved road, parking area and bathroom facilities near environmentally sensitive shoreland resources.

“You’re talking about hundreds of people visiting the site each day,” Anderson said.

The town’s effort to secure part of the Payson estate for public use quickly became controversial.

Supporters said it was a once-in-a-lifetime chance to provide public waterfront access in a coastal town that has only two small, carry-in boat launches. Opponents, many of whom live in the adjacent Wildwood neighborhood, which has an abutting beach, questioned the cost, legality and feasibility of the town’s proposal.

The Payson heirs and others complained that the developers didn’t share their plan to sell part of the estate to the town until after they secured a purchase-and-sale agreement, though revealing their plan likely would have scuttled the deal.

Amid the controversy, the developers, headed by Bateman Partners of Portland, grew more committed to helping the town acquire more public access to Casco Bay than two carry-in boat ramps.

“It transcended being a financial transaction for us and became a very personal one to help provide public access to this spectacular property,” said Nathan Bateman, vice president of Bateman Partners. “The town voted. The people have spoken. To still be trying to derail the process is very disappointing.”

The Payson heirs sent a seven-page letter to the Town Council on Dec. 2 warning that they believe the town’s plan is illegal and the land trust has failed to enforce a conservation easement intended to protect the property.

Land trust officials sent a nine-page letter to the heirs on Wednesday assuring them that the conservation easement allows for the town’s plan to provide public access and that the trust will enforce the easement to protect natural resources.

The Payson estate was listed for $6.5 million. The developers said their deal with the Payson heirs prohibits them from sharing how much they paid for it.

On Tuesday, the Planning Board and the land trust approved the developers’ subdivision plan. The developers also have agreed to let the town develop a 1.5-mile public hiking trail around the entire property.

Christopher Franklin is one Cumberland resident who’s looking forward to spending time with his family on the town’s newly acquired public waterfront.

As executive director of the Cape Elizabeth Land Trust, Franklin has extensive experience managing conservation easements. He believes that the Chebeague & Cumberland Land Trust is acting appropriately and that the town will manage a unique resource carefully, he said.

“We’re lucky to live near Casco Bay,” Franklin said. “To have a local property that is accessible to the public is, unfortunately, exceedingly rare.”