SMRID allocates eight inches per acre to district farmers

Posted on April 18, 2024 by Sunny South News

By Cal Braid
Southern Alberta Newspapers
Local Journalism Initiative Reporter

The St. Mary River Irrigation District (SMRID) held its Annual General Meeting on April 4 at the Agri-Food Hub in Lethbridge and the water allocation for growers was finalized. The District’s irrigation season is scheduled to begin the second week of May and irrigators have been allocated eight inches per acre, a number that’s on the low end of the wet scale.

David Westwood, general manager for the District, said that the AGM drew a crowd of about 200 and that the SMRID services roughly 2,500 irrigators. He explained that in an average year with good water supply, the allocation could be as high as 16 inches. A number of factors contribute to a higher allocation in a given year: supply levels in the reservoirs, ample snowpack, or low demand due to sufficient rainfall. Any or all of those could push the number up to 18 inches.

“That’s the max that I’ve seen going back over the last 20 years that we’ve ever had. We don’t go higher than that. I know some districts in southern Alberta do set higher allocations than 18 inches, but that’s the maximum we’ve ever set, at least in any modern kind of history.”

Back in 2001, a year that the District uses as a benchmark dry year, Westwood said, “We started at eight inches and it moved to 10 inches and then in 2002 we had a little better storage, and it started at nine based on snowpack that came in that year, I’m assuming. We ended up getting so much rain that spring that we finished the season with an 18 inch allocation. We completely turned around and filled all the reservoirs in the spring.” That said, this year’s eight inch per acre allocation is as low as the District has applied in any year since 2001, so ultimately, it’s been much higher but never lower since the turn of the century.

The SMRID runs north and south of Highway 3 for most of the distance between Lethbridge and Medicine Hat as well as in a small area near Weston Lake in the County of Warner. The District collects water in the Waterton, St. Mary and Milk River Ridge reservoirs from snowpack in three primary locations: Alberta’s Akamina and Montana’s Many Glacier and Flat Top mountains. The Flat Top snow pillow is normally the District’s largest snow water equivalent contributor. According to a graph that tracks the mountain snowpack in millimeters, Flat Top has received relatively sharp increases of snow since the new year began, placing its line on the graph close to the midpoint between the dry year of 2000-2001 and last year, though this year and the 2000-01 dry year both still fall below the lower quartile.

Flat Top, at 1920 metres, is the headwaters for the St. Mary, Waterton and Belly Rivers. Akamina is 1790 metres and feeds the Waterton River, and Many Glacier is 1494 metres and feeds the St. Mary River. In spite of increases in the snow pillow since February, both Akamina and Many Glacier remain well below even the previous dry year.

Westwood said it’s common for snow accumulation to increase during the latter months of winter. 

“What’s fortunate for us is that Flat Top provides our largest amount of snow water equivalent, so that’s promising for us. (It’s) where we derive the most water from snow and it’s the one that is exceeding 2001’s snow graph and is comparable to where we were last year and getting very close to the lower quartile.” In March, the SMRID reservoirs were at 48 per cent of their full supply limit (FSL). The District targets attaining 78 per cent FSL over the winter, leaving a margin for accepting spring runoff.

The reservoirs and headworks used by the SMRID are a shared resource. The headworks supply all of the six irrigation districts from the Rockies to Medicine Hat. That includes Mountain View, Southwest, Magrath, United, Raymond and St. Mary. The Blood Tribe Agricultural Project also draws from them.