South Nation Conservation (SNC) has issued an updated Flood Warning Statement for the lower Ottawa River, as waters rise following significant rains in the region. This statement is an update to the Flood Watch issued for areas along the Lower Ottawa River (Arnprior to Hawkesbury) on April 14.
Water levels are expected to continue rising within the Ottawa River Basin due to increased snowmelt associated with above normal snowpack and high temperatures over the weekend.
Most of the water currently entering the Ottawa River is originating in areas where there are no reservoirs or retention capacity. The Ottawa River Regulating Committee is managing principal reservoirs to reduce river flows to downstream areas.
The Ottawa River Regulating Committee anticipates that water levels along the main stem of the Ottawa River are expected to exceed major flood levels, impacting several streets, lawns and houses in low-lying areas. Flood levels are expected to remain well below historic high flood levels.
Impacted locations include flood-prone areas at Chats Lake, Constance Bay area, Britannia/Lac Deschênes, Cumberland, City of Clarence-Rockland, Township of Alfred Plantagenet and other vulnerable areas down to Montreal.
SNC – Areas of Concern:
- Water levels in the Rockland area are expected to rise by about 1.0 m above the current elevation* over the next 2-3 days.
MNRF – Areas of Concern:
- Water levels in the Hawkesbury area are expected to rise by about 0.50 m above the current elevation* over the next 2-3 days.
Current elevation as of 9 a.m., Monday, April 17, 2023
Peak river conditions remain dependent on snowmelt and rainfall amounts. A rainfall event is forecasted next weekend that will add water to the river at a time when flows are near flood thresholds. There is uncertainty on the rainfall amounts and the areas that could be affected.
Residents in flood-prone areas are encouraged to closely follow changing conditions and to take necessary measures. Residents are advised to stay away from watercourses where flows are high and where banks might be unstable. Parents are encouraged to explain dangers to children and provide appropriate supervision around all waterbodies.
The Mississippi Valley (MVCA), Rideau Valley (RVCA), and South Nation (SNC) Conservation Authorities monitor water levels and weather forecasts with the Ministry of Natural Resources and Forestry (MNRF) as part of the Flood Forecasting and Warning Program. Updates are provided
as conditions change.
The Ottawa River Regulating Committee will be reassessing forecast conditions and providing hydrological condition updates on its website daily at www.ottawariver.ca/forecasts.
To view current flood warnings across Ontario, visit: www.ontario.ca/law-and-safety/flood- forecasting-and-warning-program.
This Flood Warning Statement is in effect until April 28, 2023 at 5 p.m.