Water Supply Outlook for Alberta

May 2008

Mountain Snowpack

Snow accumulations in the mountains as of May 1, 2008 are generally higher in the southernmost and northernmost basins (Table 1). Measured snowpacks are generally average to above average in the Oldman River basin, below average to average in the Bow and Red Deer River Basins, average in the North Saskatchewan and Athabasca River basins, average to above average in the Smoky River basin and above average in the Peace River basin.


The mountain snowpack is an important source of water supply to reservoirs in the province. Typically the peak snowmelt runoff from the mountain areas occurs in late May or June.


Twelve snow courses and two automated snow pillow readings were taken at the end of April in the Oldman River basin, with values ranging from 42 to 258% of average. Generally the snowpack is above average although two locations in the upper Oldman River basin have below average snowpack (Table 2).


Thirteen snow course readings were taken near the end of April in the Bow River basin, with values ranging from 76 to 120% of average (Table 3). In the Highwood and Cascade River basins and the Bow River basin above Banff conditions are generally below average. Snow accumulations in the Elbow and Kananskis River basins are generally average, and are below average to average in the Spray River basin.


Four snow course measurements were taken at the end of April in the Red Deer River basin, with values ranging from 83 to 118% of average. Snow accumulations are generally near average for this time of year (Table 4).


Six snow courses were measured in the North Saskatchewan River basin at the end of April. Snow water accumulation ranged from 87 to 108% which is average for this time of year (Table 4).


In the Athabasca River basin two snow courses were taken. The two locations in the mountains recorded snow water equivalent of 86 and 135% of average, which are below average and above average respectively for this time of year (Table 4).


Snowpack in the upper Smoky River basin in British Columbia recorded snow water equivalents from 112 to 119% of normal which is average to above average and snowpack in the upper Peace River basin in British Columbia is generally above average, as reported in the B.C. Snowpack and Water Supply Outlook http://www.env.gov.bc.ca/rfc/river_forecast/bulletin.htm.


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


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