Crews have surveyed a capsized tug in the Fraser River, plugged its fuel vents and stopped the release of fuel from its tanks, according to Emergency Management B.C.

The George H. Ledcor, a tugboat with the capacity to carry 22,000 litres of diesel on board capsized late Monday night near Vancouver's Deering Island, on the north arm of the Fraser River.

How much fuel has spilled still isn't known, however there was a sheen visible in the surrounding waters and the odour of diesel in the air, local residents say.

A rainbow sheen of diesel laps on the shore of the Fraser River after a tugboat sinking. Cleanup continues. <a href="https://t.co/xWJGA4U63a">pic.twitter.com/xWJGA4U63a</a> —@ybrend

The province said there has been a "substantial" reduction in the amount of diesel fuel on the water's surface.

It said the tug is expected to be righted and removed from its current position Wednesday morning.

Beaches closed

Beaches along that section of the river, including McDonald Beach Park and Fraser River Park have been closed until further notice and rangers are warning people to keep their dogs out of the water.

"You can smell it," said Vancouver dog owner Kira Whitlock. "I hope it's cleaned up right."

UPDATE: For safety reasons, McDonald Beach Park (which includes the off-leash dog area & boat launch) is CLOSED until further notice to allow the Coast Guard & other agencies to salvage the sunken tug boat. Only boats landing will be exiting through the launch & park. <a href="https://twitter.com/hashtag/RichmondBC?src=hash&ref_src=twsrc%5Etfw">#RichmondBC</a> <a href="https://t.co/v3EbYBbMMI">pic.twitter.com/v3EbYBbMMI</a> —@Richmond_BC

Emergency Management B.C. says a wildlife assessment has been conducted and no impacts to wildlife have been found.

The tugboat, owned by Ledcor Group, is now moored upside down and submerged across the river at Sea Island.

On Monday afternoon, Ledcor Group tweeted that it was bringing in an additional, larger crane and barge to try and lift the tug on Wednesday.

A diver was also seen at the site. It is not clear whether there are efforts to pump out any remaining diesel.

A tug overturned and sank off Deering Island in the Fraser River. It has a large tank onboard and there’s a potential for a significant amount of fuel to have been released. COV environmental and Coast Guard currently assessing. <a href="https://twitter.com/hashtag/fraserriver?src=hash&ref_src=twsrc%5Etfw">#fraserriver</a> <a href="https://twitter.com/hashtag/COVemergresponse?src=hash&ref_src=twsrc%5Etfw">#COVemergresponse</a> —@CityofVancouver

Containment booms have been place around the overturned vessel and absorbent pads were deployed. The province says those will remain in place overnight Tuesday and a plan is being developed to dispose of the pads.

Crew needed rescue

According to the Canadian Coast Guard, the 20-metre tug was towing a loaded barge when it overturned at approximately 11 p.m. PT Monday.

Lelo plays by Fraser River as team starts to clean up mess after tug sank on Fraser River near Fraser River Park. <a href="https://t.co/6EvCNU5nDe">pic.twitter.com/6EvCNU5nDe</a> —@ybrend

Four crew members had to be rescued by another tugboat and are reported to be safe.

The Canadian Coast Guard is the lead responder to the incident. A surveillance flight has been scheduled for this morning and salvage crews with equipment, including a large crane, are on site.

Deering Island, which has several homes on it, is connected via bridge to Vancouver's Southlands neighbourhood, in the southwest section of the city.

Watch the containment operation in progress

It's not clear exactly how much diesel fuel has leaked into the Fraser River 0:40

With files from Yvette Brend and Liam Britten

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