Forecast for 2026-04-29

River conditions forecasts posted on 2026-04-29 by Ottawa River Regulating Committee

Water levels and flows along the main stem of the Ottawa River continue to rise slowly from Mattawa to Pembroke, while they are stable or slightly declining between Lake Coulonge and Carillon. In Mattawa, water levels are expected to exceed the major flood level today. Snowmelt is increasing in the northern part of the basin, sending more spring runoff downstream. The rainfall that began yesterday is leading to increased runoff from the northern and central parts of the basin, with volumes depending on how much additional rain falls and where.  This is expected to lead to water levels and flows increasing gradually in all locations over the next few days. Our website Forecasts section provides expected water levels over a four-day horizon in several areas. The rate of snowmelt in the northern portion of the basin and the potential for rainfall over the coming weeks remain uncertain. As a result, in the coming weeks, a second flood peak remains possible from Pembroke to the Montreal region. A rapid melt combined with rainfall could lead to water levels higher than those observed between April 19 and 22 in all locations.