An annual swimming event at a Victoria, B.C. waterway, created to celebrate the area’s clean water, had to be cancelled this year because the water turned out to be not so clean after all.

The annual Gorge Swim Fest is usually a fun swimming event designed to showcase the beauty of the Gorge Waterway, with musical performances, food and family games throughout the festival. But this year, just hours before the event was due to begin, organizers were forced to call it off.

“We learned there was a suspected sewage spill into a creek that leads into the gorge," Gorge Swim Fest Society President Jack Meredith told CTV News.

Organizers learned that the Gorge Creek, which leads into the waterway, had grown cloudy and smelly.

Esquimalt Public Works is testing water samples to determine what may have caused the water fouling, but the source of the murky substance remains a mystery.

"We're fairly certain it isn't sewage. It smells like it but we're not seeing those indicators," the agency’s Jeff Miller told CTV News, adding the cloudy water could be the result of an algae bloom.

Seventy years ago, the Gorge Waterway was highly polluted, with sewage and industrial waste that degraded the water. But clean-up efforts since the 1990s have rejuvenated the waterway, as well as the health of local fish and wildlife.

Many Swim Fest goers, including some who came to Vancouver Island from the mainland specifically for the festival, said they were disappointed the event had to be cancelled. But Miller agrees organizers did the right thing cancelling, saying "it's probably better to be prudent."

With a report from CTV Vancouver Island’s Yvonne Raymond