Important Notice: Irrigation Season Water Supply Update May 2024

May 30, 2024

Dear Irrigators,

Based on the May 1st, 2024, Irrigation Water Supply Forecast supplied by Alberta Agriculture & Irrigation (AG&I) our latest water supply update, as of May 23, 2024, indicates that we are still on course for a below average water allocation for the 2024 Irrigation Season.

The St. Mary Headworks Reservoirs, made up of the Waterton, St. Mary, and Milk River Ridge reservoirs, have been gaining in storage and are sitting at 68% of Irrigation Storage FSL (Full Supply Limit) with 316,000 acre-feet of storage. SMRID Reservoirs have made minor gains in storage since our March update and contain 172,000 acre-feet of storage, or 54% of our Irrigation FSL, compared to 274,000 acre-feet, or 86% Irrigation FSL in May 2023.

Akamina and Many Glacier’s snow pillows began to drop rapidly at the beginning of May and are showing no Snow Water Equivalent (SWE) at the elevation of the pillows, although more run off from snow at higher elevations will continue as seasonal temperatures rise. However, both snow pillows report well below normal, and remain below 2001 levels.

Flat Top Snow Pillow started to drop off early in May but held through the May long weekend with the cooler wet weather, and a slight gain was made in SWE. The pillow is reporting slightly above the lower quartile and is looking better than it was this time last year.The GoA will continue to monitor water supply forecasts within the 4 sub-basins where water-sharing agreements are applied and provide bi-weekly updates until the end of the growing season. These updates can be found at The water sharing agreement in the Oldman South Saskatchewan River basin has been activated.

As of May 20, 2024, several areas with the SMRID’s works recorded soil moisture reserves nearing 160 mm or more indicating these areas have reduced capacity to absorb additional heavy rains and are at a higher risk for local flooding should heavy rainfall facilitate high moisture reserves in these areas.

Despite recent precipitation events, water allocation, at this time, remains at 8 inches at the farm gate for the 2024 irrigation season.

We will continue to communicate with our irrigators providing scheduled monthly updates throughout the growing season. The next update is tentatively scheduled for June 27, and will include data published by AG&I on June 1.  The allocation will be subject to change based on reporting of snowpack yield and reservoir levels as the season progresses.


David Westwood
General Manager
St. Mary River Irrigation District