Water Supply Outlook April 2013

Updated: April 10, 2013

Mountain runoff forecasts (natural volumes for March to September 2013)

Milk River basin

Oldman River basin Revised April 12, 2013
  • Below average for the St. Mary River
  • Average for the Belly River, Oldman River at Brocket and Oldman River at Lethbridge
  • Slightly above average for the Waterton River
  • Slightly below average to slightly above average for April to September
  • March recorded volumes are slightly below average for the Waterton River, Oldman River near Brocket and at Lethbridge; below average for the St. Mary River and Belly River

Bow River basin Revised April 25, 2013
  • Slightly below average to above average
  • Slightly below average to above average for April to September
  • March recorded volumes are much above average for the Bow River at Banff; above average for Cascade Reservoir, Elbow River at Bragg Creek and the Bow River at Calgary; average for the Kananaskis River at Kananaskis, Highwood River at the Mouth and Spray River

Red Deer River basin

North Saskatchewan River basin
  • Average
  • Average for April to September
  • March recorded volumes are above average for Lake Abraham, much below average for Brazeau Reservoir and slightly below average for 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 April 1, 2013:

  • Oldman River basin: Generally average throughout the Oldman basin, with the exception of South Racehorse Creek which is slightly above average.
  • Bow River basin: Average to above average; Mud Lake site, located in upper Spray River basin, is much above average.
  • Red Deer, North Saskatchewan, Athabasca River basins:

    Average for the Red Deer River basin.

    Average for the North Saskatchewan River basin with the exception of Nordegg and Limestone Ridge, which are below average.

    Below average to average for the Athabasca River basin.

  • Upper Peace River basin in British Columbia: as indicated in British Columbia's Snow Survey and Water Supply Bulletin

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 March and the beginning of April in many areas of central and northern Alberta.
  • Environment Canada map of satellite estimation of plains snow water equivalent (SWE) as of April 4, 2013 is shown here. The SWE in South Central Alberta was overestimated due to melting and refreezing activities.
  • 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 March 31, 2013 is available here.

Long Lead Precipitation Outlooks

Environment Canada (issued on March 31, 2013): Above normal temperature and normal precipitationin central and southern Alberta for the April through June 2013 period.

National Oceanic and Atmospheric Administration (NOAA) (issued on March 21, 2013): An equal chance of below normal, normal or above normal temperatue and precipitation in central and southern Alberta from April to June, 2013.

Climate indicators: The NOAA reported on April 4, 2013 that neutral conditions are expected through Northern Hemisphere into Summer 2013.

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