ANACORTES, Wash. – An old railroad trestle that extends over sensitive fish and shellfish habitat caught fire Oct. 15, requiring the assistance of eight agencies, including Swinomish Police Department.

The fire is being investigated as an arson.

Emergency personnel worked overnight to extinguish the stubborn fire, which was fueled by the trestle’s creosote pilings. Containment booms were laid to contain marine pollution caused by the fire.

The trestle, which had been converted into a walking trail, extends over Fidalgo Bay, a traditional fishing and shellfish harvesting area of the Samish and Swinomish peoples. Both monitor water quality in the bay, which is affected by two nearby refineries and the trestle, which leaches creosote and restricts tidal flows.

The trestle is scheduled to be replaced as part of a broader plan to improve the health of Washington state’s marine environment by 2020.