Water levels on Ottawa River rise slightly after Wednesday’s rain

A flooded street in Gatineau is seen on April 29, 2026. (Brad Quinn/CTV News Ottawa)

Water levels on the Ottawa River have risen slightly after Wednesday’s rainfall, according to the Ottawa River Regulation Planning Board.

Levels had been declining or holding steady over the past few days with the dry weather but rose a few centimetres after 22.1 mm of rain fell in the Ottawa area on Wednesday and overnight into Thursday morning.

Levels at Lake Deschenes at Britannia are up 2 cm compared to Wednesday, while the level rose 4 cm in Hull. There was a 1 cm rise recorded in Pembroke.

The largest increase was recorded in Mattawa, going up 7 cm in 24 hours. The planning board said major flood levels were expected to be reached in Mattawa this week.

“Snowmelt is increasing in the northern part of the basin, sending more spring runoff downstream,” the planning board said Wednesday afternoon. “The rainfall that began (on Tuesday) 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.”

A flood warning remains in effect along the lower Ottawa River, according to the Mississippi Valley Conservation Authority.

“Water level increases should remain below the peaks observed last week,” the MVCA said on Monday.

“From Arnprior to Britannia the potential for major flood levels to be exceeded may be possible by the weekend. From Britannia to Hawkesbury, minor flood levels are expected to persist in some flood-prone areas, with major flood levels being exceeded in some areas by the weekend.”

The minor flood level is defined as the level at which parts of some streets, lawns and parks are beginning to flood, with no or few houses/buildings being affected.

The major flood level is defined as the level at which one or several streets are beginning to flood, with several houses/buildings or neighbourhoods being affected.

Gatineau

The City of Gatineau is watching for increased water levels this week, saying the possibility of a second flood peak cannot be ignored.

“Rapid snowmelt accompanied by rain could lead to higher water levels than those observed between April 19 and 22 in all areas,” the city said in its most recent update on Tuesday.

“Although the water has receded in recent days, affected areas remain. The reopened streets are therefore intended for local traffic only. Depending on the water levels forecast for the coming days, some recently reopened streets may change status and be closed to traffic again,” the city says.

The mayor of Gatineau says the city is monitoring the situation carefully.

“The situation right now is, of course, better than last week, but we remain careful in how optimistic we want to be, because we know that there is a possibility of a second peak,” Mayor Maude Marquis-Bissonnette told Newstalk 580 CFRA’s Ottawa at Work with Patricial Boal on Thursday. “And at the beginning of the week, the Ottawa River Regulation Planning Board was saying that this second peak could be higher than the first one. This is not what we currently see on the field, but we don’t want to be too optimistic too soon and send the wrong message to residents who still need to be careful about what can happen.”

A rain warning that was in effect on Wednesday ended early Thursday morning. The current forecast does not include any significant precipitation during the day.

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