PROVINCIAL LOW WATER LEVELS CONDITIONS REPORT

PROVINCIAL LOW WATER LEVELS CONDITIONS REPORT

July 31, 2003

Region	Precipitation (monthly)¹		Flows (monthly)²
MNR Southcentral	To date (Aug 6, 2003), watersheds in 5 Conservation Authorities (CA) are in a confirmed Low Water condition - 4 CA’s are in Level I³: (Kettle Creek, Quinte, Grand River [Mill Creek subwatershed in Level II], Ausable Bayfield); and 1 CA has watersheds in Level II: (Catfish Creek) Southern Ontario overview: Just over half of the stations reported below 80% of the average precipitation for July¹. * In the west (west of Toronto Region, north to Georgian Bay) Most stations reported below 80% of the average precipitation for July. Six stations reported below 40%.* Centrally, (north of the west half of Lake Ontario) Half of the stations reported below 80% of the average precipitation for July.* In the east (north and east from Prince Edward Region) Most stations reported above 80% of the average expected precipitation for July.* 18 month precipitation: Almost all stations reported greater than 80% of the average expected precipitation for the period February 1, 2002 through July 31, 2003 with the exception of 1 station in the Aylmer District.* 3 month precipitation: Most stations reported greater than 80% of the average expected precipitation for the period May 1 through July 31. One station in the Guelph district reported below 40%.* *Does not include any precipitation that has fallen in August. As of August 6, the Provincial Response Centre is forecasting 8 to 16 mm of rain over the next 5 days, with potential additional amounts falling locally.		Most stations reported above 70% of average using the criterion² for streamflow. Three stations in southwestern Ontario reported flows below 30%. Flood Potential: Immediate flood threat is currently low. Long term flood threat would be from widespread and extensive rainfall.
	Average Historical Precipitation Overall average July precipitation ranges from 55mm to 100mm Most stations range from 75mm to 90mm 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 July^{1 } 18 month precipitation: All stations reported greater than 80% of the average expected precipitation for the period February 1, 2002 through July 31, 2003. 3 month precipitation: Most stations reported greater than 80% of the average expected precipitation for the period May 1 through July 31* *Does not include any precipitation that has fallen in August. Northeastern Ontario is forecast to receive 5 to 20 mm of rain over the next 5 days.	Most stations reported 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 85 mm to 105 mm for July 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 for July¹. One station in the Nipigon district reported below 40%.* 18 month precipitation: Most stations reported greater than 80% of the average expected precipitation for the period February 1, 2002 through July 31, 2003 with the exception of one station in the Thunder Bay district.* 3 month precipitation: All stations reported greater than 80% of the average expected precipitation for the period May 1 through July 31.* * Does not include any precipitation that has fallen in August. Northwestern Ontario is forecast to receive 2 to 10 mm of rain over the next 5 days with potential additional amounts falling locally.	Most stations reported above 70% of average using the criterion² for streamflow. One station in the Wawa district reported flow below 30%. Flood Potential: Immediate flood threat is currently low. Long term flood threat would be from widespread and extensive rainfall.
	Average Historical Precipitation Ranges from 85 mm to 120 mm for July 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
July Conditions	All of the Great Lakes continued their seasonal fluctuations in July with the exception of Lake Erie, which rose instead of declining. Great Lakes basin precipitation for July was about 110% of average. The Lakes Superior, Michigan-Huron, Erie and Ontario basins have received 107%, 109%, 129%, and 101% of July average precipitation, respectively. During July, with the exception of Lake Ontario, the monthly mean levels of all of the Great Lakes remained below average and lower than one year ago. Lake Ontario’s levels remained above the long-term average throughout July but below last year’s levels.
Outlook⁵	The levels of Lakes Superior and Michigan-Huron are expected to continue their seasonal rises in August and their seasonal declines over the following 4 months. Levels of the other Great Lakes are expected to continue their seasonal declines over the next 5 months. With the exception of Lake Ontario, levels all of the Great Lakes are expected to remain below the monthly mean over the next 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 and temperature Outlook across the province.

Valerie von Zuben
Surface Water Monitoring Intern

August 6, 2003}