PROVINCIAL LOW WATER LEVELS CONDITIONS REPORT

PROVINCIAL LOW WATER LEVELS CONDITIONS REPORT

August 31, 2003

Region	Precipitation (monthly)¹		Flows (monthly)²
MNR Southcentral	To date (Sep 5, 2003), watersheds in 8 Conservation Authorities (CA) are in a confirmed Low Water condition - 6 CA’s have watersheds in Level I³only: (Kettle Creek, Quinte, Ausable Bayfield, Kawartha Region, Lower Thames Valley, Nottawasaga); and 2 CAs have watersheds in Level II: (Catfish Creek, Grand River) Southern Ontario overview: Most stations reported below 80% of the average precipitation for August¹. In the west (west of Toronto Region, north to Georgian Bay) Most stations reported below 80% of the average precipitation for August. Two stations reported below 30%. Centrally, (north of the west half of Lake Ontario) Most stations reported below 80% of the average precipitation for August. In the east (north and east from Prince Edward Region) Most stations reported above 80% of the average expected precipitation for August. 18 month precipitation: Almost all stations reported greater than 80% of the average expected precipitation for the period March 1, 2002 through August 31, 2003 with the exception of 2 stations in the Aylmer District. 3 month precipitation: Approximately half of the stations reported below 80% of the average expected precipitation for the period June 1 through August 31. One station in the Guelph district reported below 40%. As of September 5, the Provincial Response Centre is forecasting no rain over the next 5 days.		Most 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 widespread and extensive rainfall.
	Average Historical Precipitation Overall average August precipitation ranges from 60mm to 120mm Most stations range from 70mm to 100mm Environment Canada Summer Outlook (June-July-August)⁵ Below normal precipitation near the lower Great Lakes and St. Lawrence River, normal elsewhere. Near normal temperatures for all of southern Ontario.
MNR Northeast	Most stations reported above 80% of the average precipitation expected for August¹ 18 month precipitation: All stations reported greater than 80% of the average expected precipitation for the period March 1, 2002 through August 31, 2003. 3 month precipitation: Most stations reported greater than 80% of the average expected precipitation for the period June 1 through August 31 Northeastern Ontario is forecast to receive 0 to 6 mm of rain over the next 5 days.	Most 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 widespread and extensive rainfall.
	Average Historical Precipitation Ranges from 75mm to 100 mm for August for most stations Environment Canada Spring Outlook (June-July-August) ⁵ Above normal precipitation Near normal temperatures
MNR Northwest	Two MNR Districts are in a confirmed Level I low water condition: Dryden and Kenora Most stations reported above 80% of the average precipitation expected for August¹ 18 month precipitation: All stations reported greater than 80% of the average expected precipitation for the period March 1, 2002 through August 31, 2003 with the exception of 1 station in the Thunder Bay District. 3 month precipitation: Most stations reported greater than 80% of the average expected precipitation for the period June 1 through August 31. Northwestern Ontario is forecast to receive 0 to 9 mm of rain over the next 5 days, with potential additional amounts falling locally.	Most 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 widespread and extensive rainfall.
	Average Historical Precipitation Ranges from 80 mm to 100 mm for August for most stations. Environment Canada Spring Outlook (June-July-August) ⁵ Near normal precipitation for most of northwestern Ontario, except above normal in the far north Near normal temperatures for all of northwestern Ontario

Great Lakes⁴
August Conditions	All of the Great Lakes continued their seasonal decline in August with the exception of Lake Superior. Great Lakes basin precipitation for August was about 86% of average. The Lakes Superior, Michigan-Huron, Erie and Ontario basins have received 101%, 83%, 74%, and 82% of August average precipitation, respectively. During August, 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 levels of Lakes Erie and Ontario were higher than 1 year ago. Lake Michigan-Huron dropped below chart datum at the end of August.
Outlook⁵	Lake Michigan-Huron is expected to continue to fall below chart datum in September. Lake Superior is expected to do the same in December. Levels of all the Great Lakes are expected to continue their seasonal decline over the next 6 months. With the exception of Lake Ontario, levels all of the Great Lakes are expected to remain below the monthly mean over the next 6 months. Lake Ontario levels are expected to stay above average for the next 2 months and then drop below average for the following 4 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 and temperature Outlook across the province.

Valerie von Zuben
Surface Water Monitoring Intern

September 5, 2003}