YORK – A Maine philanthropist who left her estate to Bowdoin College would not have wanted the coastal property to be sold, her niece says.

The 23-acre estate that belonged to Mary Marvin Breckinridge Patterson in the southern Maine town of York was donated to Bowdoin College in 1974 and placed on the market last October for $5.3 million.

The sale has worried many in York because of the house’s historical and environmental significance. Recently, a bid to designate the home as a historic landmark in the town failed to win selectmen’s support.

Patterson’s niece, Isabella Breckinridge of Washington, D.C., has sent a letter to Bowdoin and York officials seeking to clarify her aunt’s wishes.

“My understanding is that Bowdoin is apparently working to make sure that the land around the River House is not covered by any conservation easements,” she said. “I thought that was doing a great disservice to my aunt and the town of York.”

Bowdoin officials have contended that Patterson knew a time could come when the house would be sold, and asked that the proceeds of a sale be used to establish a public affairs program at the college.

But many in York fear that the estate known locally as River House could be sold to a developer who could conceivably tear down the house and sell off the land.

Friends and relatives of Patterson said that would not have been Patterson’s hope for the home.

While it is unfortunate that Bowdoin College could not afford to keep the home, Breckinridge said, “My aunt trusted Bowdoin to at least keep it whole, to preserve the place.”

Scott Hood, spokesman for Bowdoin College, said there is no stipulation that the college had to maintain the home in perpetuity.

The proposal for a historic designation could be revisited if the selectmen take another vote on the issue or a citizens’ petition asks selectmen to hold a townwide referendum, said Tobin Tracey, chairman of the Historic District Commission.

“Our concern, and the town’s concern, is what if it goes to a developer and the property is divided up?” he said. “They may sell to someone who is very preservation-minded, but we can’t speculate on that.”