Officials haven’t been able to trace the source of a minor oil spill in Thomsen Harbor this weekend. The spill was a combination of diesel fuel and bilge oil.

Sitka Police received a call Saturday evening (2-28-15) reporting a diesel sheen in Thomsen Harbor, stretching from the first finger all the way to Eliason Harbor.

Coast Guard Marine Safety Detachment Supervisor Mike Wortman said the discharge quantity was less than a gallon and not recoverable.

Wortman said his team investigated a dozen potential sources, but were unable to find the culprit.

Harbor Master Stan Eliason says diesel spills are likely to come from the bilge of a boat. Spilled fuel can then get trapped under harbor floats or eat away at exposed foam. This time, the sheen dissipated with no visible damage. Eliason said that, in his 20 year career, he has seen spills happen without the owner having any clue.

“A lot of these times, folks don’t realize that their boats are discharging,” said Eliason. “It can be discharging at 3 or 4 or the morning when they’re not around. I’d recommend people just to constantly or periodically check their bilges for any water. The water will, if it gets into the bilge, it will end up kicking on that bilge pump and if there is oil present, it’s going to be pumped into the water as well.”

Wortman said that if you see an oil sheen on a navigable waterway, proper procedure is to immediately report it to the US Coast Guard. This can be done anonymously via the National Response Center at 1-800-424-8802.