Water Supply Outlook March 2012

Updated: March 7, 2012

Mountain runoff forecasts (natural volumes for March to September 2012)

Forecasts have decreased for most locations, on average by between 2 and 5% since the February 1 forecasts, except for the Red Deer River basin forecasts which increased by 1.5% and the Oldman River basin which increased by 4%.

Milk River basin
  • Average
Oldman River basin
  • Below average for the St. Mary, Belly River and Oldman River at Brocket and Lethbridge
  • Slightly below average for the Waterton River
Bow River basin
  • Slightly below average for the Cascade Reservoir and the Elbow River at Bragg Creek
  • Average for the Spray Reservoir, Kananaskis River at Kananaskis, Highwood River at the Mouth, Bow River at Banff and the Bow River at Calgary
Red Deer River basin
  • Below average to average
North Saskatchewan River basin Revised March 22, 2012
  • Much above average for the Bighorn Reservoir
  • Above average for the Brazeau Reservoir
  • Above average for the 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, 2012:

  • Oldman River basin: ranging from average to much above average at most locations. Below average at both Lee Creek in the middle St. Mary River basin and Gardiner Headwaters in the upper Castle River basin.
  • Bow River basin: highly variable in the Upper Bow River basin, but above average overall. Above average to much above average in the Kananaskis and Elbow River basins, and much above average in the Highwood River basin.
  • Red Deer, North Saskatchewan, Athabasca River basins:

    Ranges from average to much above average in the Athabasca River basin with the larger amounts at the higher elevations.

    Above average to much above average in the North Saskatchewan River, and Red Deer River basins.

  • Upper Peace River basin in British Columbia: above normal, as indicated in British Columbia's Snowpack and Water Supply Outlook

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 Spring Snowmelt Runoff Forecasts

Conditions are variable across the province, please refer to the map in the Plains Runoff Forecast section of our Maps and Data Summaries webpage.

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, 2012 is shown here. The southern plains snowpack is indicated as 10-50% of normal.
  • 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 26, 2012 is available here.

Long Lead Precipitation Outlooks

Environment Canada (issued on February 28, 2012): Temperatures are forecast to be below normal along the eastern slopes; normal elsewhere. Precipitation is forecast to be below normal in south eastern Alberta; normal elsewhere, for the March through May 2012 period.

National Oceanic and Atmospheric Administration (NOAA) (issued on February 16, 2012): Normal temperatures and precipitation are forecast in southern Alberta, for March through May 2012.

Climate indicators: The NOAA reported on February 9, 2012 that La Nina conditions will transition to neutral conditions from March to May 2012.

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