Wood coated in creosote, a coal tar product that experts say creates the effects of a slow oil spill over time, was removed from Puget Sound Thursday.

Crews with the Washington State Department of Natural Resources (DNR) spent Thursday removing toxic wood from Puget Sound around West Seattle.

The wood is coated in creosote, a coal tar product that experts say creates the effects of a slow oil spill over time. It was used as a preservative for wood in marine environments.

"It's a hydrocarbon mix of about 300 different carcinogens and a bunch of pretty nasty chemicals," explained DNR Restoration Manager Chris Robertson.

The DNR has been removing creosote coated materials from Puget Sound since 2003, totaling 50 million pounds. Still, they're only halfway done.

Studies have shown that herring eggs exposed to creosote have a high mortality rate. The chemicals also affect juvenile salmon that migrate through contaminated estuaries by reducing their growth and affecting their immune system.

"There is still a lot of it in the system," said Robertson. "There are places where you might have a lot of wood accumulating on the beach, places like Dungeness Spit or some of these parks here. We'll come back year after year after year and find another 100,000 pounds of creosote."

The DNR is asking the public for help identifying and reporting creosote-coated pilings.