By Tim Kalinowski
Local mountain snowpacks and good water levels in southern Alberta’s reservoirs to start 2020 bode well for irrigators in the year ahead.
Dennis Matis, manager of water operations with Alberta Environment and Parks based in Lethbridge, gave the good news to 2020 Irrigated Crop Production Update conference attendees at the Sandman Signature Hotel on Jan. 15. Matis was the closing speaker for the two-day event— an acknowledgement that local irrigation supply comes mainly from Mother Nature in the form of good snowpacks, and has very little to do with the human infrastructure that manages that runoff at the end of the day.
Snowpack data is collected through 10 “snow pillow” stations located throughout the mountains, which are basically large bladder sacks about three metres in diameter filled with antifreeze, explained Matis. As snow accumulates on the pillow, the weight of the snow pushes an equal weight of the antifreeze solution from the pillow up a standpipe in the adjacent instrument house which gives the measurement.
In Waterton-Akamina the reading his team is getting from the snowpack is a fullsome 110 per cent of normal for this time of year, said Matis.
“Right now we’re about 110 per cent of normal, and a year ago at this time we only had 60 per cent,” he explained to a rapt audience at the irrigation conference. “It’s looking pretty good right now; although we’re early on here. We still have about another three months to go before the peak snowpack.”
He said another key snow pillow at Glacier-Flat Top reveals a reading of 140 per cent of normal.
“A large portion of the southern tributaries that go into Alberta actually originates in Montana in Glacier National Park,” stated Matis. “We’re at about 140 per cent here. So again looking really good thus far.”
According to Matis, Many Glacier, which feeds the St. Mary River basin headwaters, is at about 130 per cent of normal. He also confirmed the snowpack above the Castle River basin is at about 140 per cent of normal, and South Racehorse, which feeds the upper Oldman River, is at about 130 per cent.
“So again, I am presenting some good news here before lunch,” Matis said, drawing some laughter from the crowd. “If history repeats itself, the trajectory for all these pillows, it does accumulate between now and April for the most part; so it’s looking good.”
Great snowpack also bodes well for reservoir water levels in the region, said Matis, but the late snow and rain of last year has already gone a long ways toward their replenishment after three high-use, dry years for irrigators.
According to Matis, the Waterton reservoir is at 53 per cent capacity already— one year ago it was basically dry at four per cent capacity. St. Mary River Irrigation District storage is already at 80 per cent for this year. The Oldman River reservoir is 63 per cent full at present, and Keho is at 89 per cent.
Looking at the statistics from the last 20 years, Matis said 2017, 2018 and 2019 were the highest draw years on record for irrigation. But, he admitted, he’ll be darned if he knows how it was being done given local reservoirs at the same time were near the lowest point they have ever been in that 20-year period. He suspects climate variability may account for some of the discrepancy.
“I am not a climate variability specialist,” he said. “I don’t pretend to be one, but all I know is things are changing. The traditional hydrograph on a lot of these rivers seems to have changed. We come along and we have our rule curves which say we will only start filling aggressively at certain times of the year, but we’re seeing the runoff happen maybe two to three weeks earlier … In the offseason, we’re going through a real exhaustive research on revisiting our rule curves in light of this climate variability where it seems a lot of the traditional snow we were getting now seems to be coming down as rainfall.”
Not that he is complaining about the rain in this instance, clarified Matis.
“Low supply every year, high demand— and yet we still manage to fill our reservoirs,” he said. “But it has just been kind of timely rainfall that has saved our butts, shall we say. And even this last year, a lot of times there is a lot of late fall irrigation— that didn’t happen (in 2019) because of the climate conditions. I daresay some things have just kind of fit in place, but not so much we (local water managers) can take credit for. So again this is going back to how we have to revisit these rule curves and optimize our reservoir regulation.”