Water Supply Outlook for Alberta

March 2004

Mountain Snowpack

Snow accumulations in the mountains as of March 1, 2004 are generally below-average in the Waterton/St.Mary, Bow, and Red Deer River basins, below-average to average in the Oldman River basin, and below-average to much-below-average in the North Saskatchewan, Athabasca, and Smoky River headwaters for this time of the year (Table 1). The mountain snowpack is an important source of water supply to reservoirs in the province. On average, the accumulation of snow at this time of the year accounts for nearly three-quarters of the seasonal total.

Eight snow courses were measured at the end of February in the Oldman River basin, with values ranging from 78 to 122% of average for this time of year (Table 2). The snowpack is generally below-average in the Waterton and St.Mary River basins and below-average to average in the Oldman River basin. Snow accumulations are much better than those observed on March 1 of both 2001 and 2003, and significantly worse than last month when the snowpack was average to above-average.

Seventeen snow courses were taken at the end of February in the Bow River basin, with values ranging from 72 to 92% of average (Table 3). Snowpack measurements are generally below-average for this time of year. Snow accumulations are generally much higher than those observed on March 1 of both 2001 and 2003, and lower than those recorded in 2002. Snow accumulations are worse than last month, when the snowpack was below-average to average.

Three snow courses were measured in the Red Deer River basin on March 1, with values ranging from 84 to 90% of average, which is below-average for this time of year. Three snow course measurements were made in the upper North Saskatchewan River basin, with accumulations ranging from 66 to 86% of average, which is below-average to much-below-average for this time of year. Three snow course measurements were made in the upper Athabasca River basin, with accumulations ranging from 61 to 66% of average in the mountains, which is much-below-average for this time of year. In the foothills area of the Athabasca River basin, one snow course was measured at 103% of average, which is average for this time of year. Red Deer, North Saskatchewan and Athabasca snow course data is available in Table 4. Snow accumulations in all three basins are generally higher than those observed last year at this time and are worse than last month due to much-below-normal precipitation during February.

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:

http://environment.alberta.ca/apps/basins/default.aspx

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