Water Supply Outlook for Alberta

May 2007

Mountain Snowpack

Snow accumulations in the mountains as of May 1, 2007 are generally higher in the north than in the south (Table 1). Measured snowpacks are much above average in the Athabasca, North Saskatchewan, Red Deer, and Upper Bow River basins, above to much above average in the Kananaskis River basin, and above average in the Elbow and Highwood River Basins. Snow accumulations are generally below average in the upper Oldman River basin. Snowpack in the upper Peace River basin, in British Columbia, is generally much above average. The mountain snowpack is an important source of water supply to reservoirs in the spring. Snow accumulation for the year is essentially complete.

Twelve snow courses and two automated snow pillow readings were taken at the end of April in the Oldman River basin. Snow at elevations above 5000 feet generally range from below normal to normal (53 to 106% of average), and all 3 locations (Table 2) below 5000 feet are much below average.

Twelve snow courses and one automated snow pillow reading were taken at the end of April in the Bow River basin, with values ranging from 108 to 166% of average, except for the one station at an elevation below 6000 ft which had a value 22% of average (Table 3). Snow accumulations are much above average upstream of Banff, above to much above average from Banff to Kananaskis, and above average in the Elbow and Highwood River Basins. Snowpack at the 4 locations upstream of Banff generally rank second highest in the past 30 years.

Three snow course measurements were taken at the end of April in the Red Deer River Basin, with values ranging from 141 to 149% of average, which is much above average. Snowpack in the basin ranges from second to fifth highest in up to 29 years of record (Table 4).

Seven snow courses were measured in the North Saskatchewan River basin at the end of April, with values ranging from 119 to 169% of average. The snowpack is generally much above average for this time of year, ranking from first to seventh highest in approximately 25 years of record (Table 4).

Two snow courses were measured in the Athabasca River basin at the end of April, with values of 161 and 162 % of average, which are much above average, ranking second and sixth highest in 38 years of record (Table 4).

Snowpack in the upper Peace River basin in British Columbia is much above average, as seen in the B.C. Snowpack and Water Supply Outlook (http://www.env.gov.bc.ca/rfc/river_forecast/bulletin.htmm).

At twelve snow course sites, real-time snow accumulation can be monitored using snow pillows. Snow pillows can be viewed by choosing any mountainous southern basin, and snow data, in the two drop down menus at:


Snow water equivalent values on the snow pillow may or may not match the snow course value at a particular location. While snow pillow data is very valuable information, the quantity of snow on the pillow is only representative of the accumulation at that specific spot. A snow course survey is measured at numerous spots and provides a more representative value of snow in the area. In some locations, there can be considerable difference between the snow pillow and snow course values. Factors such as wind and exposure of the site can cause the snow pillow values to be significantly different from the snow course survey. The snow pillow graphs on our website show the daily average snow water equivalent. The monthly snow survey is the average of all measurements conducted within five days of the end of the month. Also, where snow pillow and snow course measurements are available for the same site, snow pillow records tend to be much shorter (10-15 years) in length compared to the snow course sites. As a result, the difference in the average value between the snow pillow and the snow course can be attributed to snow water equivalent being derived two different ways (physically measured compared to an instrument reading), site location and length of data record. In some cases, the values can deviate by 10-20%. Therefore, while snow pillows are excellent for analyzing trends and for monitoring accumulation between snow surveys, snow course values should always be used when considering the quantity of snow at a particular location as they best represent that area.

Click here to see a map of snow course locations

Plains Snowpack

Plains snowpack was essentially melted throughout Alberta.

For technical enquires about this web page please contact Alberta Environment - Environmental Management Water Management Operations Branch at AENV-WebWS@gov.ab.ca