Emerging sandbars in the South Saskatchewan River near Finlay Bridge in Medicine Hat show the relatively low water level in the river. That could change with a major rainstorm predicted this weekend over southern Alberta.--News Photo Collin Gallant
@MedicineHatNews
Up to four inches of rain across southern Alberta, and double that amount in the southern foothills, are expected this weekend in the first major widespread rainfall of the spring, which could give a boost to reservoirs and river levels across the south.
It has also led to high-stream flow advisories issued Thursday afternoon for the Bow and Oldman rivers, along with tributaries including the Elbow River within the City of Calgary.
The City of Medicine Hat stated it does not expect dangerous levels on the South Saskatchewan River, which is flowing below normal levels on Thursday, but is prepared to mobilize if conditions change.
“We have comprehensive emergency management plans, expertly trained personnel and specialized equipment ready to respond to these types of events,” said Merrick Brown, city director of emergency management. “We have entered an enhanced monitoring mode for this event, and we are a well-prepared organization.”
A special weather statement from Environment and Climate Change Canada for the City of Medicine Hat says rain and high winds will begin Friday and continue through Sunday, depositing between 100 to 200 millimetres (2 to 4 inches) of precipitation.
That forecast extends for most of the prairie south of Red Deer, while in the foothills between Hinton and Cardston, amounts could total between two to eight inches.
That comes after irrigation districts prioritized holding water to raise storage levels, and combined with an early end to runoff, has left river levels generally lower than usual at this time of year.
“Its been a fairly dry spring to this point, but that will change rapidly with this forecast,” said Richard Phillips, chair of the Alberta Irrigation Districts Association and GM of the Bow River Irrigation District, based in Vauxhall.
“Rivers are certainly lower than usual … Most reservoirs are in good shape, a little lower than ideal, but the rain this weekend could improve that,” he added, citing relatively above average levels of off-stream storage along the Bow basin.
The Oldman basin storage levels are lower, comparatively, including a below average rating in the huge Oldman Reservoir.
“With this amount of rain (expected), it would be surprising if they didn’t fill,” said Phillips.
The South Saskatchewan River was flowing at about 100 cubic metres per second on Thursday afternoon – well below the historical low and high ranges of between 200 and 700 CMS in the middle of June.
The Oldman River at Lethbridge was at about 25 CMS, below a range of 50 to 275 CMS, and the Bow at the Bassano Dam was 100 CMS compared to a average range of 110 CMS to 350.
Major reservoirs on the Bow – like Lake Newell and Crawling Valley – were nearing capacity according to the provincial water storage summary.
Also above normal further south were Lake McGregor and Travers Reservoirs on the Oldman, while the Old Man dam itself was below normal at about 60 per cent full.
The St. Mary’s Irrigation District reported at the end of May that its reservoir levels were about 20 per cent higher than in the spring of 2024, when drought concern led to widespread reductions.
But current runoff from the eastern slopes that feed the basin had concluded earlier than both last year, and in the historically dry year of 2000-2001.
That group’s next update is due June 27.
