A converted tugboat that sank near Richmond, B.C. on Wednesday night leaked a minimal amount of fuel into the Fraser River.

A witness named Brian said the 52-foot tugboat was anchored in the channel between Graybar Pier and Annacis Island. Somehow the anchor became loose and the boat started drifting with the tide, eventually colliding with a piling.

"There was nobody on board the boat at the time. And the water came in and started washing over the side of the boat and next thing you know the boat was sinking," said the witness.

Brian says he phoned the Coast Guard and harbour authorities when he realized what was happening. Officials say a minimal amount of unrecoverable fuel has leaked into the Fraser River.

Now there is a debate over what to do with the boat — and who will pay for the clean up.

A second witness to the sinking said the tugboat is probably is not worth saving.

"It would be thousands of dollars. You'd have to get airbags and divers and all kinds of crap. It's a lot of work," he said.

"It's too bad. It's a beautiful boat, nice wood inside. That's what happens when you're not careful and you don't anchor your boat properly."

This is the second time in as many weeks a tugboat has sunk. On Jan. 14, a restored 112-year-old tugboat spilled 1,500 litres of diesel fuel when it sank near the government dock in Squamish, B.C.

With files from CBC's Tim Weekes