Calgary's mayor says the city may have to improve the signage along the Bow River upstream of the Harvie Passage.

A man in his 30s died Monday after his raft flipped on the Bow River.

The man was with three friends, going through the features of the new Harvie Passage just before 4 p.m. MT.

He was transported to Foothills Medical Centre in life-threatening condition, where he later died.

The whitewater park is the redesigned Calgary weir, which officially opened this season after four years of construction.

Naheed Nenshi stressed Tuesday that the area is for experienced water sport enthusiasts, not recreational rafters.

"I’m a little concerned that the messaging around has been unclear. Some people may have the impression that floating through the Harvie Passage is like floating down the Elbow on a sunny day and it just isn't," said Nenshi.

All four of the rafters were wearing life jackets.

The Calgary Fire Department’s Jason Doyscher said the Harvie Passage is a dangerous area.

"It does take some skill to manoeuvre through this area. People need to be aware that, even though it’s warm out, they need to take those precautions and make sure that they understand the water conditions — the water is still quite murky, there is still a lot of debris in this area," said Doyscher.

Doyscher said the high water in the area is cause for concern.

"At this time we’re asking people just to stay off the water, completely, at all, there’s no reason to be on it at all down here, unless you are a skilled individual."

Doyscher said the area is only for experienced boaters, but with the high water, even they shouldn't be on the river.

Fire officials have asked people to stay off the rivers as melting snow in the mountains has increased water levels and the speed of the current.

A CBC videographer was at the river while the incident happened. The video posted above shows the people navigating through the passage before the accident.

The redesigned weir

Harvie Passage is located on the Bow River slightly downstream of the Calgary Zoo.

It features two separate channels, labelled as Class 2 and Class 3 rapids. The features are designed for trained whitewater kayakers and river rafters.

The weir, often called a "drowning machine," was known for its heavy undertow.

This is the first death on the weir since it was redesigned.