PROVINCIAL LOW WATER LEVELS CONDITIONS REPORT

PROVINCIAL LOW WATER LEVELS CONDITIONS REPORT

Update for September 14, 2003

Region	Precipitation (monthly)¹		Flows (monthly)²
MNR Southcentral	To date (Sept 16, 2003), watersheds in 11 Conservation Authorities (CA) are in a confirmed Low Water condition - 9 CA’s have watersheds in Level I³only: (Kettle Creek, Quinte, Ausable Bayfield, Kawartha Region, Lower Thames Valley, Nottawasaga Valley, Upper Thames Region, Long Point Region, Hamilton Region); and 2 CAs have watersheds in Level II: (Catfish Creek, Grand River) All stations reported below 45% of the average precipitation for the second week of September¹ (By the end of the second week, 45% of the average precipitation for September would indicate a trend toward the average for the month). Some areas received no precipitation at all. As of September 16, the Provincial Response Centre is forecasting 6-10 mm of rain over the next 5 days for southwestern Ontario. The PRC is forecasting up to 65mm of rain Friday in southeastern and southcentral Ontario as the remnant of hurricane Isabel passes through. Southern Ontario has received 0 to 40 mm of precipitation over the last 48 hours.		Most stations reported flows below 70% of average using the criterion² for streamflow. Flood Potential: The remnant of hurricane Isabel is projected to downgrade to a tropical storm and track north through New York State crossing Lake Ontario, near Kingston, early in the evening Friday. It is projected to continue north to leave the province early Saturday morning crossing the upper Ottawa Valley. Precipitation is expected to begin early Friday morning with generally 65mm over a 12 to 15 hour period eastern and central Ontario. At this time we are not anticipating any major flooding problems from this event. It is possible that local imbedded thunderstorms will be associated with this system producing locally higher amounts. However, it is too early to forecast.
	Average Historical Precipitation Overall average September precipitation ranges from 50mm to 100mm Most stations range from 75mm 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	All but one station reported below 45% of the average precipitation expected for the second week of September¹ (By the end of the second week, 45% of the average precipitation for September would indicate a trend toward the average for the month) Northeastern Ontario is forecast to receive 26 to 43 mm of rain over the next 5 days, with potential additional amounts falling locally. Northeastern Ontario has received 2 to 45 mm of precipitation over the last 48 hours.	Most stations reported flows below 70% of average using the criterion² for streamflow. Flood Potential: Immediate flood threat is currently low. Hurricane Isabel is not expected to bring significant rainfall to Northeastern Ontario. Long term flood threat would be from widespread and extensive rainfall.
	Average Historical Precipitation Ranges from 85mm to 115 mm for September 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 45% of the average precipitation expected for the second week of September¹ (By the end of the second week, 45% of the average precipitation for September would indicate a trend toward the average for the month) Northwestern Ontario is forecast to receive 18 to 37 mm of rain over the next 5 days, with potential additional amounts falling locally. Northwestern Ontario has received 0 to 6 mm of precipitation over the last 48 hours.	Most stations reported flows above 70% of average using the criterion² for streamflow. Flood Potential: Immediate flood threat is currently low. Hurricane Isabel is not expected to bring significant rainfall to Northeastern Ontario. Long term flood threat would be from widespread and extensive rainfall.
	Average Historical Precipitation Ranges from 85 mm to 90 mm for September for most stations. Environment Canada Fall Outlook (September-October-November) ⁵ Above normal precipitation Below normal temperatures

^{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.

Valerie von Zuben
Surface Water Monitoring Intern

September 16, 2003}