PROVINCIAL LOW WATER LEVELS CONDITIONS REPORT

PROVINCIAL LOW WATER LEVELS CONDITIONS REPORT

April 30, 2003

Region	Precipitation (monthly)¹		Flows (monthly)²
MNR Southcentral	To date (May 5, 2003), watersheds in 11 Conservation Authorities (CA) are in a confirmed Low Water condition - 6 CA’s are in Level I³: (Kettle Creek, Lake Simcoe, Mississippi Valley, Quinte, Saugeen Valley, St. Clair,); and 5 CA’s have watersheds in Level II: (Ausable-Bayfield, Cataraqui, Catfish Creek, Crowe Valley, Grand River). Southern Ontario overview: Half of the stations reported below 80% of the average for April. In the west (west of Hamilton Region, north to Georgian Bay) Almost half of the stations reported below 80% of the average precipitation, with seven stations in the Guelph District reporting less than 40% of average. Centrally, (north of the west half of Lake Ontario) Almost half of the stations reported less than 80% of the average, with two stations in the Aurora District reporting below 40%. In the east (north and east from Prince Edward Region) Most stations reported below 80% of the average expected precipitation for April. 18 month precipitation: Almost all stations reported greater than 80% of the average expected precipitation for the period November 1, 2001 through April 30, 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 February 1 through April 30. Snow on the ground as of Apr 30^th: Southern Ontario is reporting no snow on the ground. As of May 5, the Provincial Response Centre is forecasting 20 to 35 mm of precipitation over the next 5 days, with potential additional amounts resulting from thunderstorm activity in the southwestern portion of the region.		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 to moderate in the southwestern portion of the region due to heavy rainfall. Flood potential elsewhere in the region is low. Long term flood threat would be from widespread and extensive 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 80% of the average precipitation expected by the end of April¹. One station in the Sudbury District reported below 60%. 18 month precipitation: All stations reported greater than 80% precipitation for the period of November 1, 2001 to April 30, 2003. 3 month precipitation: Most stations reported greater than 80% of the average expected precipitation for the period February 1 through April 30. Snow on the ground as of Apr 30^th: Northeastern Ontario is still reporting snow in some areas. Northeastern Ontario is forecast to receive 10 to 20 mm of rain over the next 5 days.	Only one flow station in the Cochrane District reported below 100% of average using the criterion² for streamflow. Flood Potential: Immediate flood threat is currently moderate to high in the far northern portions of the region due to ice break-up on rivers feeding James and Hudson Bay.
	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 Nearly half of the stations reported below 80% of the average precipitation expected by the end of April¹, with two stations reporting less than 40%. 18 month precipitation: All stations reported greater than 80% precipitation for the period of November 1, 2001 to April 30, 2003 with the exception of one station in the Thunder Bay District. 3 month precipitation: Most stations reported below 80% of the average expected precipitation for the period February 1 through April 30. One station in the Nipigon District reported less than 40% of average. Snow on the ground as of Apr 30^h: Northwestern Ontario is reporting no snow on the ground for most areas. Northwestern Ontario is forecast to receive 8 to 20 mm of rain over the next 5 days.	Nearly half of the stations reported below 50% of average using the criterion² for streamflow. Flood Potential: Immediate flood threat is currently moderate to high in the far northern portions of the region due to ice break-up on rivers feeding Hudson Bay.
	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

Great Lakes⁴

April Conditions

Great Lakes basin precipitation for April was about 86% of average. The Lakes Superior, Michigan-Huron, Erie and Ontario basins have received 105%, 89%, 67%, and 68% of April average precipitation, respectively.

Last month’s precipitation combined with snowmelt runoff caused levels to rise on all the Great Lakes in April. However, the level of Lakes Michigan-Huron rose by less than its usual amount.

Levels on all of the Great Lakes remain below average and lower than one year ago.

Outlook⁵

The levels of all the Great Lakes will rise over the next few months, Ontario more than average, Erie less that average and Superior and Michigan-Huron about average. All the lakes are expected to peak at their usual times this summer.

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

May 5, 2003}