PROVINCIAL LOW WATER LEVELS CONDITIONS REPORT

October 31,  2003

 

Region

Precipitation (monthly) 1

Flows (monthly)2

MNR Southern

(previously referred to as Southcentral)

·         To date (Nov 7, 2003), watersheds in 11 Conservation Authorities (CA) are in a confirmed Low Water condition - 10 CAs have watersheds in Level I3 only: (Ausable Bayfield, Kawartha Region, Kettle Creek, Long Point Region, Lower Thames Valley, Nottawasaga Valley, St. Clair Region, Quinte, Upper Thames Region, Grand River); and 1 CA has watersheds in Level II: (Catfish Creek)

·         Southern Ontario overview: Most stations reported above 80% of the average precipitation for October1.

·         In the west (west of Toronto Region, north to Georgian Bay) Most stations reported above 80% of the average precipitation for October.

·         Centrally, (north of the west half of Lake Ontario) Most stations reported above 80% of the average precipitation for October.

·         In the east (north and east from Prince Edward Region) All stations reported  above 80% of the average expected precipitation for October.

·         18 month precipitation: Almost all stations reported greater than 80% of the average expected precipitation for the period May 1, 2002 through October 31, 2003 with the exception of 2 stations in the Aylmer District.

·         3 month precipitation: Most stations reported above 80% of the average expected precipitation for the period August 1 through October 31.

As of November 7, the Provincial Response Centre is forecasting 14 to 23 mm of rain Monday and Tuesday with potential additional amounts falling locally. Southern Ontario has received an average of 25 mm of rain since November 1. A number of stations have received over 40 mm of rain.

·         All but 2 stations reported flows above 70% of average using the criterion2 for streamflow.

 

Flood Potential:

 

·         Immediate flood threat is currently low. Long term flood threat would be from significant or heavy rainfall.

 

 

 

Average Historical Precipitation

·         Overall average October precipitation ranges from 35mm to 110mm

·         Most stations range from 60mm to 90mm

Environment Canada Fall Outlook (September-October-November)5

·         Above normal precipitation for the eastern most portion of  S. Ontario, normal elsewhere.

·         Near normal temperatures for all of southern Ontario.

MNR Northeast

·         Most stations reported greater than  80% of the average precipitation expected for October1

·         18 month precipitation: All stations reported greater than 80% of the average expected precipitation for the period May 1, 2002 through October 31, 2003.

·         3 month precipitation: All but 2 stations reported greater than  80% of the average expected precipitation for the period August 1 through October 31

Northeastern Ontario is forecast to receive 16 to 30 mm of snow over the next 5 days with potential additional amounts falling locally.

·         All but 2 stations reported flows above 70% of average using the criterion2 for streamflow.

 

 

Flood Potential:

 

·     Immediate flood threat is currently low. Long term flood threat would be from significant or heavy rainfall.

 

Average Historical Precipitation

·         Ranges from 75mm to 105 mm for October for most stations

Environment Canada Fall Outlook (September-October-November) 5

·         Above normal precipitation

·         Below normal temperatures

MNR Northwest

·         One MNR District is in a confirmed Level I low water condition: Dryden

·         Most stations reported below 80% of the average precipitation expected for October1 .

·         18 month precipitation: All stations reported greater than 80% of the average expected precipitation for the period May 1, 2002 through October 31, 2003.

·         3 month precipitation: Most stations reported greater than  80% of the average expected precipitation for the period August 1 through October 31.

Northwestern Ontario is forecast to receive 4 to 12 mm of snow over the next 5 days.

·         All but 1 station reported flows above 70% of average using the criterion2 for streamflow.

 

 

Flood Potential:

 

·         Immediate flood threat is currently low. Long term flood threat would be from significant or heavy rainfall.

 

 

Average Historical Precipitation

·       Ranges from 45 mm to 70 mm for October for most stations.

Environment Canada Fall Outlook (September-October-November) 5

·          Above normal precipitation

·          Below normal temperatures

 

Great Lakes4

October Conditions

·         Levels of Lake Superior, Michigan-Huron and Erie declined by their usual amounts during October. Lake Ontario also declined but by less than its usual amount.

·         Great Lakes basin precipitation for October was about 94% of average. The Lakes Superior, Michigan-Huron, Erie and Ontario basins received 82%, 89%, 111% and114% of average precipitation, respectively.

·         During October, with the exception of Lake Ontario, the monthly mean levels of all of the Great Lakes remained below average. The levels of Lakes Superior and Michigan-Huron remained significantly lower than one year ago, while the level of Lakes Erie and Ontario were higher than 1 year ago. Lake Michigan-Huron is below chart datum.

Outlook5

·         Lake Michigan-Huron is not expected to rise above chart datum until next summer. Lake Superior is expected to drop below chart datum in December.

·         Levels of all the Great Lakes are expected to continue their seasonal decline over the next 4 months with the exception of Lake Superior which will continue to decline over the next 5 months.

·         With the exception of Lake Ontario, levels of all the Great Lakes are expected to remain below the monthly mean over the next 6 months. Lake Ontario levels are expected to drop below average in November and remain below average for 5 months.

 

 

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 July 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 Outlook across the province and medium confidence to the temperature Outlook.

 

Val von Zuben

Surface Water Monitoring Officer

November 7, 2003