KINGSTON, Wash. -

The Kingston-Edmonds ferry route is back in service with one boat as an early morning fuel leak is investigated and cleaned up.

Washington State Ferries spokeswoman Marta Coursey says 15 gallons of diesel fuel spelled from the ferry Walla Walla before service began on Monday morning. The spill created a sheen on the water.

The Edmonds-Kingston route is the second busiest in the system, carrying 3.8 million passengers last year.

Both the Walla Walla and the Spokane were surrounded by oil booms at the Kingston terminal on Monday morning.

Coursey recommends holiday travelers take the Seattle-Bainbridge or Seattle-Bremerton ferries as an alternative.