Rain on the way would delay water level decrease on Ottawa River

A rainy few days could extend the flooding along the Ottawa River, just as water levels were beginning to stabilize.

The Ottawa River Regulation Planning Board says water levels are slowly approaching major flood thresholds from Chats Lake, in the Ottawa Valley, to the Montreal area.

The board warns heavy rain in the forecast may result in “additional level increases” in some locations along the Ottawa River starting on Monday, depending on the amount and location of the rainfall.

Manon Lalonde, executive engineer with the Ottawa River Regulation Secretariat, told Newstalk 580 CFRA’s “CFRA Live with Andrew Pinsent” Saturday morning that were it not for the rain in the forecast, people living along the banks of the Ottawa River would start to see water levels go down.

“Most of the melt water from the central part of the basin has made its way to the river and is leaving the system,” she said. “If it weren’t for the rain that we’re seeing over parts of the basin… levels would start to decline everywhere.”

Lalonde notes that Environment Canada has issued rainfall warnings for parts of western Quebec, warning of up to 30 mm by Sunday.

“The main effect of that rain will be to delay the decline of the water level. It is always possible that there will be some increases in some locations. It’s really tough to tell at this part of time,” Lalonde added.

“These additional increases that may come starting Monday, we’re talking additional inches, we’re not talking feet. This is what we’re seeing over the next few days.”


Ottawa saw some brief showers Saturday morning. Environment Canada was forecasting about 5 mm of rain early Saturday followed by a partly sunny day with a high of 23 C. Wind gusts could reach 50 km/h, Saturday. The UV index is 9, or very high.

However, more rain is expected Saturday evening and overnight. The forecast calls for 10 to 15 mm of rain and the risk of a thunderstorm with a low of 7 C.

Sunday’s forecast includes another 5 to 10 mm of rain and a high of 14 C.

Overnight lows in the low single digits are forecast for the start of the next week. Monday could see a few flurries in the morning changing to rain showers as the temperature rises. The high is 13 C.

There is a small chance of showers in the long-term outlook through next week, though most days should see sunny breaks. Highs are in the low teens.

–With files from CTV News Ottawa’s Josh Pringle and Peter Szperling.

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