Coast guard officials now say as much as 5,000 litres of diesel fuel may have spilled into Vancouver's False Creek near Fisherman's Wharf on Sunday night.

A small fishing vessel has been identified as the source of the spill, says coast guard spokesperson Jeff Brady.

"We've identified the source of the spill which is a small fishing vessel in the area," he said. "The source is contained and we don't see any risk of its further polluting right now."

Original estimates had put the spill as large as 1,000 litres, but shortly after 10 a.m. PT, Brady revised the estimate to somewhere between 500 and 5,000 litres.

The spill was first reported to the Canadian Coast Guard around 10:30 p.m. PT Sunday.

The Western Canada Marine Response Corporation, which is contracted to clean up oil spills in the harbour, arrived at around 3:30 a.m. PT Monday and laid out about 300 metres of booms to contain the spill, according to Brady.

Oil booms have been laid out to contain the spill. (Canadian Coast Guard/Twitter)

Mechanical skimmers were deployed to scoop up the fuel and a helicopter flew over the spill to confirm the areas with the highest concentration of fuel have been contained.

Transport Canada is expected to conduct an investigation to determine the exact source of the spill.

No lasting impacts expected

Despite the strong smell, the spill is unlikely to have any lasting impacts on the environment or people, said officials.

"Diesel is a non-persistent oil and evaporates quite fast, about 75 per cent of it in 72 hours would evaporate, and that's why we have a strong smell in the air on such a hot day," said coast guard spokesman Jeff Brady.

The fuel was visible on the surface of the water on Monday morning. (Farrah Merali/CBC)

"We're going to have a lot of evaporation which is good for getting it out of the marine environment, but might be bad for people in the area who might have scratchy eyes or scratchy throat possibly."

Boaters are asked to avoid the boomed area until the spill is cleaned up. Residents are also advised to close windows and doors to keep the smell out.

The seawall was closed in the area between the Granville and Burrard bridges..

Deputy city manager Sadhu Johnston said the coast guard notified the city about the spill around 2:30 a.m. PT Monday.

He said that ever since the much larger bunker fuel spill from a container ship in the harbour earlier this year, the coast guard and WCMRC have been quicker to notify the city about spills.

Google Maps: Fisherman's Wharf, Vancouver