Water Supply Outlook August 2013

Updated: August 9, 2013

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

Forecasts have increased in the North Saskatchewan River basin and Oldman River near Brocket since the May 1 forecast. The increase is due to the heavy precipitation that fell in southern and central Alberta during the months of May through July. Forecasts in the Milk River basin was decreased due to lower than average precipitation from May through July.

Milk River basin

Oldman River basin

  • Much below average to much above average for the Oldman River basin.
  • Below average to above average for August to September
  • March - July recorded volumes are much below average for St. Mary River; slightly below average for Waterton River; average for Belly River; slightly above average for the Oldman River at Lethbridge; much above average for the oldman River near Brocket.

Bow River basin

  • Due to the June 2013 flooding, the Bow River basin Water Supply Outlook has been discontinued for the remainder of the 2013 Water Supply Outlook season.

Red Deer River basin

  • Due to the June 2013 flooding, the Red Deer River basin Water Supply Outlook has been discontinued for the remainder of the 2013 Water Supply Outlook season.

North Saskatchewan River basin

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 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 over time. Streamflow volume forecasts are updated monthly from February to May, and again in July depending on precipitation and streamflow conditions. Recorded 2013 volumes are preliminary and subject to change.

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

Mountain snowpack (issued in December to June next year)

Plains Spring Snowmelt Runoff Forecasts (issued in March and April each year)

Plains Snowpack (issued in March and April each year; Cypress Hills mid to late January and February)


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 August 6, 2013 is available here.

Long Lead Precipitation Outlooks

Environment Canada (issued on July 31, 2013): Normal precipitation for the northern half of the province and above normal precipitation for the southern half of the province.

National Oceanic and Atmospheric Administration (NOAA) (issued on July 18, 2013): Slightly below normal chance of above normal temperatures in extreme southern portion of Alberta for August through October 2013. Equal chance of below normal, normal, or above normal precipitation.

Climate indicators : The NOAA reported on August 8, 2013 that ENSO-neutral conditions are expected to continue through the Fall of 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