Water Supply Outlook March 2011

Updated: March 16, 2011

Mountain runoff forecasts (natural volumes for March to September 2011)

Oldman River basin
  • Slightly below average to average for the St. Mary, Belly River and Waterton River at Waterton Park
  • Above average for Oldman River at Brocket and average for Oldman River at Lethbridge
Bow River basin
  • Slightly below average for Elbow River at Bragg Creek and Highwood River at the Mouth
  • Average for Spray Reservoir, Kananaskis River at Kananaskis, Cascade Reservoir and Bow River at Calgary
  • Slightly above average for Bow River at Banff
Red Deer River basin
  • Slightly below average
North Saskatchewan River basin
  • Average for the Bighorn Reservoir, Brazeau Reservoir and North Saskatchewan River at Edmonton

Precipitation can have a major impact on water supply between now and the end of September. The forecasts above assume that precipitation over the remainder of the winter period and through the summer will be normal. The range of possible precipitation scenarios is large however, and as a result, probable range forecasts and a minimal precipitation forecast of natural runoff volume are also provided for each individual basin. Since more information becomes known over time, forecast ranges will narrow. Streamflow volume forecasts are updated monthly from February to May, and again in July.

Check our Forecaster's Comments throughout the month for updated information regarding runoff conditions.

Mountain snowpack

Snow accumulations measured in the mountains as of March 1, 2011:

  • Oldman River basin: ranging from above average to much above average at all locations
  • Bow River basin: highly variable in the Upper Bow River basin, but above average overall. Below average to average in the Elbow River basin, and average to above average in the Highwood River and Kananaskis River basins.
  • Red Deer, North Saskatchewan, Athabasca River basins:

    Below average to average in the Red Deer River basin.

    Near average in the mountains and above average to much above average in the foothills in the North Saskatchewan River basin.

    Above average to much above average in the mountains and much above average in the foothills in the Athabasca River basin.

Mountain snowpack is an important source of water supply to reservoirs in the spring. Accumulation at this time of year typically accounts for nearly three-quarters of the seasonal total.

Plains snowpack

  • Map of Snow course measurements taken at the end of February and the beginning of March in many areas of central and northern Alberta. Cypress Hills snow measurements were taken in mid-February.

  • Environment Canada map of satellite estimation of plains percent of normal snow water equivalent (SWE) as of March 1, 2011 is shown here. Southern plains snowpack is indicated as over 200% of normal, snow water content amounts are generally above average to much above average.
  • Alberta Agriculture publishes maps of modelled plains snow accumulations and accumulations as compared to normal.


Contoured maps of precipitation amounts and as a percent of normal for the past month and for current and recent seasons are available here. Maps of precipitation amounts for the most recent day, week and month to date are available here.

Soil Moisture

Alberta Agriculture models soil moisture for non-mountainous, agricultural areas of Alberta. Modelled soil moisture compared to average as of February 28, 2011 is available here.

Long Lead Precipitation Outlooks

Environment Canada (issued on March 1, 2011 for the March through May 2011 period): below normal temperature for the entire province, and normal precipitation for much of Alberta, except for below normal precipitation for the northeastern corner of the province, and above normal precipitation for west-central Alberta.

National Oceanic and Atmospheric Administration (NOAA) (issued on February 17, 2011 for March through May 2011): below normal temperatures and an even chance of below normal, normal or above normal precipitation in southern Alberta.

Climate indicators: The NOAA reported on February 10, 2011 that "Nearly all of the ENSO model forecasts weaken La Nina in the coming monhs...." and "[a] majority of the models predict a return to ENSO-neutral conditions by May-June-July 2011, although some models persist a weaker La Nina into the Northern Hemisphere summer 2011."

Note that forecasting weather for such a long time period into the future is very difficult, and so the historical accuracy has been variable, dependent on location and time period, and is often low, more so for precipitation than temperature. Environment Canada provides an assessment of their forecast method's historical accuracy on their website.

Reservoir storage

Water storage volumes in the major irrigation and hydroelectric reservoirs of the Milk, Oldman, Bow, Red Deer North Saskatchewan, and Athabasca River basins is updated each weekday and is available in the Provincial Reservoir Storage Summary.


Background information on the Water Supply Outlook is available in Frequently Asked Questions

Media Contact:
Communications Division, Alberta Environment
Phone: (780) 427-6267