Photo courtesy of Ross Lavigne

By Scott Roblin

South Saskatchewan River

Sharp rise and fall of South Saskatchewan an anomaly for City

Jul 9, 2020 | 5:34 PM

MEDICINE HAT, AB – Flow rates on the South Saskatchewan River have dropped drastically from a week ago, however the City of Medicine Hat say they’re not out of the woods yet.

Well into the month of July, the City is still taking a close look at the South Saskatchewan as it has been an unusual season of steep rising and falling levels.

Addressing media at a press conference on Tuesday, director of emergency management Merrick Brown said it’s been a strange year monitoring the river.

“Typically in June we can usually confidently say that the risk is low to the point where we don’t have to worry about it,” said Brown. “But, this year is a little bit of an anomaly.”

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On July 3, the South Saskatchewan reached its highest flow rates in over three years at around 1,200 cubic metres per second.

In the week since, the flow rates have been halved at 640 cubic metres per second and have become much more manageable for the City.

The sudden rise and fall is something Brown and his team have been watching over the last few months, a far cry from the steady rise that often peaks around the third week of June.

“You see a nice curve in flow rates with that peak right around the end of June,” said Brown. “So, we’ve seen very much peaks and valleys this year with flow rates and that’s based on the volatility of the weather this year. I still can’t confidently say there is no risk given this volatility, so there’s still some monitoring to do with this.”

A major reason for the volatility in flow rates has been wild patterns of precipitation in southern Alberta over the spring and summer months which have affected various river basins.

Zahid Qureshi, a flow forecast engineer with Alberta Environment, told CHAT News that the Bow River, Oldman River, and South Saskatchewan River water basins have all met the average rainfall amounts expected per month, with the Bow and South Saskatchewan already exceeding those levels.

“This was different because most of the precipitation didn’t fall in the mountain area, but fell near lower sloped areas,” said Qureshi.

According to Qureshi, the Bow River basin peaked around May 24 and has since receded, while the Oldman River basin didn’t peak until last Friday raising water levels and flow rates locally.

Estimating what the rest of the summer is trickier to predict for the Alberta River Forecast Centre, however flow rates on the South Saskatchewan are expected to slow down even more heading into the weekend.

“For the next five days I can tell you from the forecasting there is not much precipitation in almost all of Alberta,” said Qureshi. “So, the water level is declining and it will keep declining at Medicine Hat. In the long term, hopefully we will see a normal pattern and then it will decline.”

Despite the expected drop in speed on the river, the City is still asking residents to stay away from the South Saskatchewan and its banks until more consistent levels are recorded.

Average flow rates in July for the South Saskatchewan usually sit around 500 cubic metres per second, so Brown said there’s still some waiting to do.

“With those flow rates you get quite a bit of debris coming down the river as well,” said Brown. “When you start looking at watercraft use, debris and watercraft use don’t mix well together.”