Forecast for 2026-05-04

River conditions forecasts posted on 2026-05-04 by Ottawa River Regulating Committee

Spring runoff is slowly decreasing in the northern part of the basin as snow continues to melt. Water levels and flows on the Ottawa River from Mattawa to Pembroke have stabilized, while levels downstream, from Lake Coulonge to the Montreal Region, have started to slowly decrease. Over the next week, water levels and flows are expected to start gradually declining from Mattawa to Pembroke, and to continue decreasing downstream from Lake Coulonge down to the Montreal Region, as no major rainfall is forecast on the northern part of the basin. However, because large volumes of water are still expected to come from the northern part of the basin, water levels along the main stem of the river are expected to remain generally high over the next week. The northern part of the basin will remain vulnerable to heavy rainfall in the coming weeks; therefore, further increases in water levels from Mattawa to Lake Coulonge due to high spring runoff cannot be ruled out.