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Water Conditions Statement Update #1: Flood Warning — Lower Ottawa River

April 20, 2023 

This FLOOD WARNING statement is an update to the Flood Warning issued for areas along the Lower Ottawa River (Arnprior to Hawkesbury) on April 17th, 2023.

Water levels are expected to continue rising within the Ottawa River Basin due to snowmelt, combined with forecasted rainfall starting Friday and continuing 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 will continue increasing over the next few days before stabilizing near the major flood level, 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.

MVCA areas of concern:

  • Water levels in the Constance Bay area are expected to rise by about 0.15 m above the current elevation* within the next day and remain high over the next four to five days.

RVCA areas of concern:

  • Water levels in the Britannia area (Grandview Road and the Belltown Community) are expected to rise by about 0.20 m above the current elevation* over the next two to three days.
  • Water levels east of Cumberland Village (Boise Village, Morin Road, Leo Lane) are expected to rise by about 0.25 m above the current elevation* over the next two to three days.

SNC areas of concern:

  • Water levels in the Rockland area are expected to rise by about 0.45 m above the current elevation* over the next two to three days.

MNRF areas of concern:

  • Water levels in the Hawkesbury area are expected to rise by about 0.40 m above the current elevation* over the next two to three days.

* Current elevation as of 6:00 a.m., Thursday, April 20, 2023.

Peak river conditions remain dependent on snowmelt and rainfall amounts. The rain event forecasted this weekend 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. It should be noted that water level forecasts do not account for wind and wave impacts.

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, Rideau Valley, and South Nation Conservation Authorities monitor water levels and weather forecasts with the Ministry of Natural Resources and Forestry 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 5:00 PM.

South Nation Conservation

MEDIA CONTACT:
Erin Thorne, Communications Specialist,
ethorne@nation.on.ca, 1-877-984-2948.

FLOOD DUTY OFFICER:
Jason Symington, Water Resources Specialist – Engineering
jsymington@nation.on.ca, 1-877-984-2948.

Definitions:

  • Water Conditions Statement: Water Safety: indicates that high flows, melting ice or other factors could be dangerous for such users as boaters, anglers, and swimmers but flooding is not expected.
  • Water Conditions Statement: Flood Outlook: gives early notice of the potential for flooding based on weather forecasts calling for heavy rain, snow melt, high winds, or other conditions.
  • Flood Watch: potential for flooding exists within specific watercourses and municipalities. Municipalities, emergency services and individual landowners in flood-prone areas should prepare.
  • Flood Warning: flooding is imminent or occurring within specific watercourses and municipalities.

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