River will remain high into June
Normal volumes not expected until June, and further rain could renew flooding
The Ottawa River’s water level is falling fast, but regulators warn that even with the best weather forecast it won’t be back to normal until the end of June — and heavy rain could bring new flooding.
The Ottawa River Regulating Committee updated its flood measurements Monday morning.
The Ottawa River measured near Parliament Hill is now down 1.16 metres from its peak. It fell 18 centimetres from Sunday morning to Monday morning.
The river is down 56 cm at Lac Deschênes, which rises and falls more slowly because the river is wider there. It is down 99 cm at Thurso.
The most recent measurements of water flow come from Sunday. It was flowing at a rate of 6,750 cubic metres per second at Carillon, down about 2,000 from the peak but still unusually high.
The agency reported that most heavily flooded areas between Lac Coulonge and the Hawkesbury/ Grenville region, which includes Ottawa-Gatineau, were now free of high waters.
Water levels are expected to continue their decline down to what are known as “apprehension levels” by the end of May.
Apprehension levels are those at which the river typically encroaches on waterfront properties, the agency explains. And as long as levels remain above apprehension levels, flooding can happen again if there’s widespread and heavy rain.
“Even under favourable weather conditions, levels are not expected to return to their normal range until the end of June,” the agency said.
According to a statement from the Rideau Valley Conservation Authority, little to no increase in levels occurred in the Rideau watershed or in the areas the RVCA monitors on the Ottawa River, including Lac Deschene, Petrie Island and Boise Village.
“These areas are no longer under Flood Warning status as levels decline by about 10 centimetres per day.”