PROVINCIAL LOW WATER LEVELS CONDITIONS REPORT

Update for May 7, 2003

Region

Precipitation (monthly) 1

Flows (monthly)2

MNR Southcentral
  • To date (May 8, 2003), watersheds in 10 Conservation Authorities (CA) are in a confirmed Low Water condition - 5 CA’s are in Level I3: (Kettle Creek, Mississippi Valley, Quinte, Saugeen Valley, St. Clair,); and 5 CA’s have watersheds in Level II: (Ausable-Bayfield, Cataraqui, Catfish Creek, Crowe Valley, Grand River).
  • Southern Ontario overview: Most of the stations reported below 25% of the average precipitation by the first week of May1. (By the end of the first week, 25% of the average precipitation for May would indicate a trend toward the average for the month). Note: Some data from May 2, 3 and 4 is missing, therefore values may actually be higher than reported.
  • Snow on the ground as of April 30th:

Southern Ontario is reporting no snow on the ground.

As of May 8, the Provincial Response Centre is forecasting 20 to 30 mm of precipitation over the next 5 days, with potential additional amounts falling locally.
  • Next update May 14

Flood Potential:

  • Immediate flood threat is currently low. Long term flood threat would be from widespread and extensive rainfall.

 

Average Historical Precipitation

  • Overall average May precipitation ranges from 60mm to 90mm
  • Most stations range from 60mm to 80mm

Environment Canada Spring Outlook (March, April, May)5

  • Above normal precipitation for most of southern Ontario, except normal in the southwest.
  • Near normal temperatures for all of southern Ontario.

MNR Northeast

  • Nearly all stations reported below 25% of the average precipitation expected by the first week of May1. (By the end of the first week, 25% of the average precipitation for May would indicate a trend toward the average for the month). Note: Some data from May 2, 3 and 4 is missing, therefore, values may actually be higher than reported.
  • Snow on the ground as of April 30th: Northeastern Ontario is still reporting snow in some areas.

Northeastern Ontario is forecast to receive 18 to 25 mm of rain over the next 5 days with potential additional amounts falling locally.
  • Next update May 14

Flood Potential:

  • Immediate flood threat is currently moderate to high in the far northern portions of the region due to ice break-up on rivers feeding James and Hudson Bay.

 

Average Historical Precipitation

  • Ranges from 65 mm to 80 mm for May for most stations

Environment Canada Spring Outlook (March-April-May) 5
  • Above normal precipitation
  • Below normal temperatures

MNR Northwest

  • Two MNR Districts are in a confirmed Level I low water condition: Dryden and Kenora
  • All of the stations reported below 25% of the average precipitation expected by the first week of May1. (By the end of the first week, 25% of the average precipitation for May would indicate a trend toward the average for the month). Note: Some data from May 2, 3 and 4 is missing, therefore, values may actually be higher than reported.
  • Snow on the ground as of April 30th: Northwestern Ontario is reporting no snow on the ground for most areas.

Northwestern Ontario is forecast to receive 20 to 25 mm of rain over the next 5 days with potential additional amounts falling locally.
  • Next update May 14

Flood Potential:

  • Immediate flood threat is currently moderate to high in the far northern portions of the region due to ice break-up on rivers feeding Hudson Bay.

 

Average Historical Precipitation

  • Ranges from 55 mm to 70 mm for May for most stations

Environment Canada Spring Outlook (March-April-May) 5

  • Above normal precipitation for most of northwestern Ontario, except normal in the northeast
  • Below normal temperatures, except near normal in the southwest

 

1Environment Canada’s synoptic stations are equipped to measure snow. Precipitation gauges from dataloggers often are not set up to measure snow adequately. The resulting errors plus the elimination of many of the readings for these gauges means our precipitation coverage is poor during months with snow.
2For each gauge used in the analysis the average flow is calculated for July, and August and September from the historical record. The minimum of these three values is compared to the past month’s average flow. During the winter months most streams are partially filled or covered over with ice. This ice reduces the cross-section of the stream resulting in flow readings that are higher than actual. This error is corrected in the historical record. Thus the observed, relative to the historical minimum, is also higher than the actual in streams with significant ice conditions.
3 Level I conditions initiate the formation of a Water Response Team (WRT) which encourages a voluntary 10% reduction in water use. At Level II the WRT encourages a further 10% reduction by restricting non-essential water use; level III represents the condition where there is insufficient supply of water to meet all needs which may result in regulation of water use.

4Great Lakes summary includes information from Environment Canada, Great Lakes - St. Lawrence Regulation Office and the Detroit District U.S. Army Corps of Engineers.

5Outlook provided by Environment Canada. Environment Canada has assigned very low confidence to this season’s precipitation and temperature Outlook across the province.

Valerie von Zuben

Surface Water Monitoring Intern
May 8, 2003