PROVINCIAL LOW WATER LEVELS CONDITIONS REPORT

PROVINCIAL LOW WATER LEVELS CONDITIONS REPORT

Update For April 21, 2003

Region	Precipitation (monthly)¹		Flows (monthly)²
MNR Southcentral	To date (April 22, 2003), watersheds in 15 Conservation Authorities (CA) are in a confirmed Low Water condition - 9 CA’s are in Level I³: (Kettle Creek, Lake Simcoe, Long Point, Lower Trent, Maitland Valley, Mississippi Valley, Quinte, Saugeen Valley, St. Clair,); and 6 CA’s have watersheds in Level II: (Ausable-Bayfield, Cataraqui, Catfish Creek, Crowe Valley, Grand River, Upper Thames). Southern Ontario overview: the majority of stations reported below 70% of the average April precipitation in the third week of April¹. (By the end of the third week, 70% of the average precipitation for April would indicate a trend toward the average for the month). Snow on the ground as of Apr 21^st: Southern Ontario is reporting no snow on the ground. As of April 22, the Provincial Response Centre is forecasting up to 3mm of precipitation over the next 5 days, with additional amounts falling as snow in eastern Ontario and rain in southwestern Ontario.		Next update April 30. Flood Potential: Immediate flood threat is currently low, but if conditions continue, the long- term flood threat would be from heavy and extended rainfall.
	Average Historical Precipitation Overall average April precipitation ranges from 50mm to 100mm 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	Most stations reported greater than 70% of the average precipitation expected in the third week of April¹. (By the end of the third week, 70% of the average precipitation for April would indicate a trend toward the average for the month). Snow on the ground as of Apr 21^st: Northeastern Ontario is reporting no snow on the ground for most areas. Northeastern Ontario is forecast to receive no precipitation over the next 5 days.	Next update April 30. Flood Potential: Immediate flood threat is currently moderate in some parts of northwestern Ontario due to recent heavy rainfall and high river flows. The long- term flood threat would be from rapid snowmelt and/or continuing extensive rainfall.
	Average Historical Precipitation Ranges from 50mm to 65 mm for April 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 Half of the stations reported below 70% of the average precipitation expected in the third week of April¹. (By the end of the third week, 70% of the average precipitation for April would indicate a trend toward the average for the month). Snow on the ground as of Apr 21^st: Northwestern Ontario is reporting no snow on the ground for most areas. Northwestern Ontario is forecast to receive up to 3 mm of rain over the next 5 days.	Next update April 30. Flood Potential: Immediate flood threat is currently moderate in some parts of northeastern Ontario due to recent heavy rainfall and high river flows. The long- term flood threat would be from rapid snowmelt and/or continuing extensive rainfall.
	Average Historical Precipitation Ranges from 35mm to 60 mm for April 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

April 22, 2003}