River Update #5 - South Sask. River still Rising, Upstream Levels Falling

The South Saskatchewan River at Medicine Hat just upstream from the confluence of the Ross and Seven Persons creeks on Wednesday afternoon. (Photo Alex McCuaig)

River levels along the upper reaches of the Bow and Oldman basins are cresting but streamflows continue to elevate downstream along the South Saskatchewan River Wednesday afternoon.

The flood watch that had been in effect for the Bow River at Lake Louise has been reduced to a high streamflow advisory which is still in place along the entirety of the basin. That holds true as well for the entire Oldman basin.

Watercourse levels on the tributaries into the Oldman reservoir are also beginning to subside with outflows from the dam also being significantly curtailed from 350 cubic metres per second to 250 m³/s.

The Piikani Nation has issued a local state of emergency citing rising water levels and substantial rainfall having impacted the community.

A Facebook post by the Piikani from earlier this week noted Brocket - located just downstream from the Oldman reservoir - was facing challenges from both the increased release from the dam and rising levels from Pincher Creek.

The outflow of the Oldman dam continues discharging water Wednesday but at a reduced rate than previous days. (Government of Alberta)

While river levels on the Oldman and Bow rivers are falling upstream of the South Saskatchewan mouth near Bow Island, downstream is a different story.

The South Saskatchewan River at Medicine Hat is continuing to see rising levels, hitting its highest streamflow rates since 2013, though still far below those flood levels.

As of Wednesday afternoon, the river at Medicine Hat is running at more than 1,200 m³/s, a far cry from the daily average record set in 2013 of 4,400 m³/s or the record instantaneous peak hit in 1995 of 5,110 m³/s.

But the river is expected to continue to rise.

The Oldman at the mouth is running at 780 m³/s and the Bow 641 m³/s which will likely result in streamflows downstream of the Grand Forks in excess of 1,400 m³/s at Medicine Hat by days end.

Neither the Oldman nor Bow rivers have appeared to peak at the confluence.

But streamflows from the Oldman River at Lethbridge have begun to subside while levels on the Bow river below the Bassano Dam have stabilized at around 800 m³/s Wednesday afternoon.

Despite the rising river, no flooding is anticipated in Medicine Hat.

The city is taking precautions due to the rising river levels, closing riverside parks, boat launches and trails along the banks of the South Saskatchewan River while also warning residents of the dangers or rising watercourse levels.