Water Supply Outlook August 2011

Updated: August 10, 2011

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

Forecasts have increased significantly in the Oldman River, Bow River, Red Deer River and North Saskatchewan River basins since the May 1 forecasts. The increase is due to the heavy precipitation that fell in southern Alberta during the months of May and June.

Oldman River basin

Bow River basin

Red Deer River basin

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 2011 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 1, 2011 is available here.

Long Lead Precipitation Outlooks

Environment Canada (issued on August 1, 2011): Temperatures are above normal in southeastern and northeastern Alberta from August to October 2011 and normal for the rest of the province. Precipitation is normal in east central and northeastern Alberta and below normal for the rest of the province.

National Oceanic and Atmospheric Administration (NOAA) (issued on July 21, 2011): An even chance of below normal, normal, or above normal temperature and precipitation in southern Alberta, from August to October 2011.

Climate indicators : The NOAA issued on August 4, 2011: ENSO-neutral (El Nino/Southern Oscillation) is expected to continue in the Northern Hemisphere in the fall of 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