PORTLAND — The state wants the owner of a vessel responsible for a 180,000-gallon oil spill to not only restore the environment to its original state but also improve it and increase public shoreline access.

Maine agencies are preparing to submit a final damage claim to the Julie N’s owner that includes several restoration projects based on a two-year study of the impact of the oil spill in Portland Harbor.

The report describes the damage to 25 acres of salt marsh, the killing of 27 cormorants, gulls and other birds, and the loss of 1,380 visits to a city walking trail and boat launch.

Tests on clams, mussels and lobsters showed elevated levels of hydrocarbon pollution.

“Any time you have a substantial spill, there’s going to be some injury,” said Paul Van Cott of the Maine Department of Environmental Protection. “Even though we did a great job cleaning up here, we left almost 40,000 gallons of oil in the system.”

Nearly 180,000 gallons of oil spilled into the harbor Sept. 27, 1996, when the tanker Julie N slammed into the old Portland Bridge and ripped a gash in its hull. It was the worst oil spill in the harbor’s history.

Maine’s damage claim proposal could be sent to the tanker owner, Amity Product Carriers Inc., by the end of the month, Van Cott said.

State officials and environmental advocates now see the damage claim as a way to reduce hydrocarbon pollution that routinely washes into the harbor.