Forecast for 2023-05-04

River conditions forecasts posted on 2023-05-04 by Ottawa River Regulating Committee

Between 45 and 90 mm of precipitation fell over the basin from Saturday April 29 to Wednesday May 3 causing flows and levels to increase rapidly on the main stem of the Ottawa River. Levels and flows have peaked at Mattawa and Pembroke but are expected to continue rising elsewhere. Levels are expected to peak tomorrow at Lake Coulonge and on Friday from Chats Lake down to the Hawkesbury / Grenville area. Levels should remain below the historic levels of 2019 (by as much as: 25-35 cm in Lake Coulonge, Chats Lake, and Lake Deschenes; and 40-50 cm along the reach between Ottawa / Gatineau and the Hawkesbury / Grenville area). Please refer to the forecast section of our website for more information about the expected peak levels. Water levels and flows are expected to stabilize over the weekend and should start to decline slowly next week with the return of sunny and drier weather. Reservoirs in the northern part of the watershed, which are being used to store runoff and minimize flooding downstream, are rapidly filling. Once reservoirs are full, they will have little capacity to reduce river flows in downstream areas. Levels will therefore remain susceptible to further rise should additional significant rainfall occur over the coming few weeks.