Provincial officials warn Calgary's weir remains dangerous for inexperienced paddlers despite changes to make it safer.

The weir, renamed the Harvie Passage, recently reopened after four years of construction.

The province and the city opted to change the weir’s original design after it was discovered the structure produced a strong undertow.

"Although the Harvie Passage is a safer, more enjoyable recreation site, all users are asked to remain alert, follow signage, and wear proper safety equipment, including personal floatation devices and helmets on the new rapids and all water courses in the province," a news release by the Alberta government states.

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

As part of the safety upgrade, crews made two channels of varying difficulty for users.

The main channel, rated as a Class 3 rapid, is suitable only for trained whitewater kayakers and river rafters.

A less turbulent Class 2 rapid is located on the south side of the river. Officials urge inexperienced paddlers to portage around the channel.

The changes also allow fish to swim upriver through the passage, protecting them from pelicans and other predators.

The weir was built in 1908 to divert water to the Western Irrigation District in southern Alberta.