Oil spill cleanup under way on Seattle's Lake Union

The Washington State Department of Ecology is cleaning up an unknown type of oil that spilled in Lake Union on Thursday.

Ecology doesn't yet know where the oil came from, a news release from the department said.

Ecology spokesman Larry Altose said the spill covers about 2 acres of water on the lake, and an environmental cleanup company has so far recovered about 40 gallons of oil along the piers and shoreline. A sheen of oil still covered part of the eastern side of the lake between the former National Oceanic and Atmospheric Administration pier and the Lake Union Drydock Thursday night, and Altose said Ecology's technology isn't capable of removing such a thin layer off the water. Whatever oil can't be collected from the shore overnight will have to dissipate on its own.

A sample of the oil will be subjected to a lab test to determine the type and source of the spill. The oil is yellowish and has a petroleum odor, Altose said.

So far, Ecology hasn't received any reports of harm to wildlife, a department news release said.

Anyone who has information or tips about the spill's source should call Ecology's 24-hour spill-reporting line at 425-649-7000.