Water Supply Outlook July 2009

Updated: July 15, 2009

Mountain runoff forecasts (natural volumes for March to September 2009)

Forecasts have decreased greatly since May 1 due to very dry weather, with precipitation generally 40 to 60% of normal for May through June

Milk River basin
  • Below to much below average except below average for Western Crossing
  • Below average except below average to average for Western Crossing July to September
  • March - June recorded volumes below to much below average except Western Crossing below average
Oldman River basin Bow River basin
  • Much below average, except below to much below average for the Highwood River and Lake Minnewanka and below average for the Elbow River
  • Below average for July to September, except below to much below average for the Bow River at Calgary and much below average for the Kananaskis River
  • March - June recorded volumes much below average, except below to much below average for the Highwood River and below average for the Elbow River and Lake Minnewanka. Banff was 5th lowest in 91 years of record, and Calgary was 10th lowest.
Red Deer River basin North Saskatchewan River basin
  • Much below average, 8th lowest in 91 years of record for Edmonton, second lowest in 41 years at Brazeau Reservoir and 4th lowest in 30 years at the Bighorn Reservoir
  • Below average except much below average (5th lowest in 44 years of record) at Brazeau Resrvoir July to September
  • March - June recorded volumes much below average, lowest on record (41 years) for Brazeau, 5th lowest in 91 years for Edmonton, and second lowest in 30 years for Bighorn

Precipitation can have a major impact on water supply between now and the end of September. The forecasts above assume that precipitation through the remainder of 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, March-September volume forecast ranges will narrow. Streamflow volume forecasts are updated monthly from February to May, and again in July, and due to the dry conditions, again this August. Recorded 2009 volumes are preliminary and subject to change.

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

Precipitation

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 July 7, 2009 is available here.

Long Lead Precipitation Outlooks

Environment Canada (issued on July 1, 2009): temperature and precipitation for the July through September 2009 period:

  • below normal precipitation in the mountains, above normal along the Saskatchewan border, and normal elsewhere in Alberta
  • above normal temperatures in southern and central Alberta, normal for northern Alberta

National Oceanic and Atmospheric Administration (NOAA) (issued on June 18, 2009): below normal precipitation and above normal temperatures in southern Alberta, for July through September 2009.

Climate indicators: The NOAA reported on July 9, 2009 that El Nino conditions are developing, and are expected to last through the coming winter.

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.

Questions

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

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