RISING LEVELS
After heavy rain in Alberta, Gardiner Dam is increasing water outflow which will raise the city’s river levels
Heavy rainfall in southern Alberta is expected to cause the river through Saskatoon to rise by about 1.5 metres.
Environment Canada forecasts 60 to 160 millimetres of rain in southern parts of the Alberta, arriving near the anniversary of last year’s devastating floods.
In response to the heavy rains, which will strengthen the flow of rivers in Saskatchewan and Alberta, the Water Security Agency is increasing the outflow from the Gardiner Dam to 900 cubic metres per second from 280.
“It’s a balancing act,” said Patrick Boyle, spokesperson of the Water Security Agency. “This is proactive and based on uncertainty ... We don’t want any floods, but at the same time Lake Diefenbaker, where the dam is, is Saskatoon’s water supply.”
A further increase may be necessary, depending on how much rain falls in Alberta, he said.
“We advise all river users to use extreme caution while walking close to the shoreline or who plan on going in the river, because it puts people and anyone who would rescue them at risk,” said assistant fire chief Morgan Hackl.
Doug Porteous of the Meewasin Valley Authority agreed that vigilance around the river is key. He recommends novice canoeists and kayakers avoid the river when the flow is stronger than 600 cubic metres per second.
“This water comes from the base of the Gardiner Dam, so it’s very cold, and with flows this high, it can be very dangerous,” Porteous said.
These levels and flows are similar to the release in late May. This time, however, the fire department has no plans to close the boat launch unless the outflow increases to more than 1,000 cubic metres per second.
“May was successful in terms of accidents, but we did have the launch closed because we expected higher flows,” Hackl said. “Now we’ll be monitoring the river closely because the launch is still open.”
The MVA will close some trails, and most sandbars will be underwater, Porteous said. The Poplar Bluffs canoe launch is also closed due to slumping.
Last year, the river flow through Saskatoon peaked at 2,000 metres per second.
Water levels in the river below Tobin Reservoir are expected to rise about 0.6 metres above the current level, similar to the levels experienced in late May.
Parts of Alberta are bracing for flooding, but Calgary officials said they anticipate only minor floods from rainfall, if anything.
Last year, the Calgary flood followed 345 millimetres of rain.
“What happens next here depends on how much rain falls and how long it lasts. (The river) could go down, up or stay the same,” Boyle said. “That’s nature.”