The Canadian Coast Guard says it's trying to identify the source of a diesel smell and sheen covering Vancouver's False Creek.
It says it received a report of the apparent pollution around 6:20 p.m. Monday, but couldn't determine the source due to heavy rain and poor visibility.
The rainbow sheen was clearly visible to commuters crossing Cambie Bridge Tuesday morning.
Michelle Imbeau, a spokeswoman with the Coast Guard, says crew members from their Kitsilano base were using "remotely piloted aircraft" to determine the source.
She says they observed "multiple patches of non-recoverable rainbow sheen" in the area, but were still unable to work out where it was coming from.
Imbeau says the Coast Guard is working with the province and the City of Vancouver to determine if the pollution came from land-based outfalls from recent heavy rain.