An uncontained tugboat oil spill fouls Seattle waterways

A tug towing a barge out of the Duwamish River toward Ballard polluted local waters this week. The state Department of Ecology says the tug spilled up to 150 gallons of hydraulic oil on Tuesday. A propeller shaft break may have been the cause.

Kersti Muul, a wildlife biologist and urban conservation specialist who lives in West Seattle, reported the spill to the West Seattle Blog. Muul said these kinds of incidents happen too often, and prevention methods should be required by law.

Photos show an oil sheen on the water off Harbor Island and the West Seattle Bridge. A spokesperson for the Department of Ecology said the agency decided to let the oil dissipate on its own because containment efforts were not likely to be effective. Muul called that the lesser of two evils, because booming oil concentrates it, which can lead to more damage.

Ecology officials told KUOW they’re investigating the timeline of the leak and can't say yet when it was stopped. They said the tug’s owner would have a diver inspect the vessel to determine whether it had lost its propeller and shaft, or if there was a different issue.

Muul said that while any spill is unwelcome, the timing of this one coincides with the arrival of multiple migrating birds, including Caspian terns and purple martins. She added that marbled murrelets also like the area, and are on an exponential decline in Washington state.

RELATED: Most of Western Washington's largest Caspian tern colony is dead. Can the seabirds rebound?

The state hotline for reporting a spill is 800-OILS-911.