PROVINCIAL LOW WATER LEVELS CONDITIONS REPORT

PROVINCIAL LOW WATER LEVELS CONDITIONS REPORT

May 31, 2003

Region	Precipitation (monthly)¹		Flows (monthly)²
MNR Southcentral	To date (June 5, 2003), watersheds in 8 Conservation Authorities (CA) are in a confirmed Low Water condition - 3 CA’s are in Level I³: (Kettle Creek, Quinte, Saugeen Valley); and 5 CA’s have watersheds in Level II: (Ausable-Bayfield, Cataraqui, Catfish Creek, Crowe Valley, Grand River). Southern Ontario overview: Most of the stations reported above 80% of the average precipitation for May¹. In the west (west of Toronto Region, north to Georgian Bay) Most stations reported above 80% of the average precipitation for May. Centrally, (north of the west half of Lake Ontario) Most stations reported above 80% of the average precipitation for May. In the east (north and east from Prince Edward Region) Most stations reported above 80% of the average expected precipitation for May with the exception of one station that reported below 40%. 18 month precipitation: Almost all stations reported greater than 80% of the average expected precipitation for the period December 1, 2001 through May 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 March 1 through May 31. As of June 5, the Provincial Response Centre is forecasting 10 to 18 mm of rain over the next 5 days, with potential additional amounts falling locally.		Only one flow station in the Bancroft District reported below 100% 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 May precipitation ranges from 60mm to 90mm 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	All but one station reported above 80% of the average precipitation expected for May¹. 18 month precipitation: All stations reported greater than 80% precipitation for the period of December 1, 2001 to May 31, 2003. 3 month precipitation: All stations reported greater than 80% of the average expected precipitation for the period March 1 through May 31. Northeastern Ontario is forecast to receive 5 to 18 mm of rain over the next 5 days with potential additional amounts falling locally.	All stations reported greater than 100% 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 65 mm to 80 mm for May 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 80% of the average precipitation for May¹. 18 month precipitation: All stations reported greater than 80% precipitation for the period of December 1, 2001 to May 31, 2003 with the exception of one station in the Thunder Bay District. 3 month precipitation: Most stations reported less than 80% of the average expected precipitation for the period March 1 through May 31. Northwestern Ontario is forecast to receive 5 to 15 mm of rain over the next 5 days with potential additional amounts falling locally.	Nearly half of the stations reported below 100% of average using the criterion² for streamflow. Two stations in the Fort Frances District reported below 70% of average. Flood Potential: Immediate flood threat is currently low. Long term flood threat would be from widespread and extensive rainfall.
	Average Historical Precipitation Ranges from 55 mm to 70 mm for May 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

Great Lakes⁴

May Conditions

All of the Great Lakes continued their seasonal rise in May.

Great Lakes basin precipitation for May was about 131% of average. The Lakes Superior, Michigan-Huron, Erie and Ontario basins have received 110%, 122%, 163%, and 160% of May average precipitation, respectively.

Monthly mean levels of all of the Great Lakes remained below average and

lower than one year ago. Lake Ontario’s level rose above the long-term average on May 27.

Outlook⁵

The levels of all the Great Lakes are expected to rise over the next month and peak at their usual times this summer. Lakes Erie, Superior and Michigan-Huron are expected to remain below the long term average over the next few months, while Lake Ontario is expected to exceed the average.

The levels of Lakes Superior and Michigan-Huron are not expected to rise above chart datum

until June or July.

^{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

June 5, 2003}