Town officials say the $25,000 penalty Michael Pantaleo owes the state for ignoring environmental laws to protect shorelines should serve as a cautionary tale for other waterfront homeowners.

Bill Carter, chairman of the Conservation Commission, said residents on the town’s ponds and lakes should think twice about home or landscape improvements. They need to understand state environmental laws. Ignoring them is costly, he said.

According to court records, Pantaleo laid down a new beach, built a patio and retaining wall, installed a dock and made other improvements. In October 2006, state officials had a look at his Arlington Pond property at 20 Glen Road, but weren’t impressed.

Since Pantaleo had twice been rejected for a permit to build a retaining wall, the improvements were a willful violation of the Shoreline Act and wetlands laws, said Allen Brooks, senior assistant attorney general.

“We look at the conduct of the person. He had previously applied for the permits for retaining walls and he had been turned down, and then he did that plus some other things,” Brooks said. “That indicated to us higher culpability.”

Pantaleo could not be reached for comment, but his attorney, Brian Quirk, said Pantaleo had fully cooperated with the state Attorney General’s Office and the Department of Environmental Services to resolve the matter.

The court-approved settlement Pantaleo reached with state officials earlier this month fined him $40,000, with $15,000 suspended on condition he not violate environmental laws for three years.

Pantaleo also was required to restore his land. Carter estimates that alone might have set the homeowner back another $25,000 to $30,000.

“Reconstruction could be as much as that fine and that’s a lot of money for the homeowner of that property,” Carter said. “This should be used as a learning exercise for anyone who might decide to do something wrong, because the state will take this serious and prosecute.”

Neighbor Steve Sapienti had a different view. “I heard about this, and I know he spent a lot of money to put that up there,” said Sapienti, 22. “I was shocked to see that the state made him take it down.”

According to Howie Glynn, president of the Arlington Pond Protective Association, most shoreline homeowners know to work with town officials to get permits before making improvements. But doing it the right way can also be costly. To help, the association will guide residents through the town or state approval process, he said.

Though they’ve helped residents for years, even the association doesn’t know the process backwards and forwards, Glynn said.

“We don’t know all the rules,” he said. “I wouldn’t want to accept that responsibility.”