Officials are reminding all users of Calgary's Bow River about the dangers of swimming and boating around the weir over the long weekend.
In a release, officials with Alberta Environment say currents at the base of the weir downstream of St. George's Island, near the Calgary Zoo, and at Wyndam-Carseland Provincial Park are powerful enough to capsize large boats.
Once caught in the current, officials say, even strong swimmers may be unable to free themselves.
Users are reminded the weirs are clearly marked with signs along the riverbanks and suspended from upstream bridges. Users are strongly urged to stay clear of the weirs.
Construction is underway on the weir in order to make the river safer for users.
The construction zone's restricted area extends from the boom upstream of the weir to about 500 metres downstream of the weir.
It's expected construction will be complete and the weir will be open for recreational use in 2012.