This FLOOD WARNING is an update to the Flood Warning statement issued May 1, 2025, for areas along the Lower Ottawa River (Arnprior to Hawkesbury).

Water levels and flows have been steadily rising along the Ottawa River due to seasonal rainfall combined with ongoing snowmelt in the northern basin. Flows and water levels are expected to stabilize over the coming days.

According to the Ottawa River Regulation Secretariat, flood-prone areas from Arnprior to Hawkesbury remain at risk. Current forecasts suggest that water levels on the main Ottawa River will remain 80 - 150 cm below the 2019 historic flood levels, and below 2023 peak levels.

• Pembroke to Britannia: Minor flood levels have been exceeded, with potential for major flooding in some locations depending on the speed of snowmelt and the amount of rainfall received.
• Gatineau (Hull Marina) to Hawkesbury: Minor flood thresholds are expected to be exceeded; peak levels are expected to stay below major flood limits.

Elevated water levels are forecasted to remain relatively stable until May 9, 2025, with an update to follow.

This advisory includes flood-prone locations such as Lake Coulonge, Chats Lake, Britannia / Lac Deschênes, Pointe-Gatineau, Cumberland, Clarence-Rockland, and Hawkesbury.

Area-Specific Forecasts;

Mississippi Valley Conservation Authority (MVCA):

Constance Bay: Elevated conditions are expected to remain stable, with possible decrease later in the week.

Rideau Valley Conservation Authority (RVCA):

Britannia (Grandview Rd, Belltown Community):Elevated conditions are expected to remain, with possible decrease later in the week. Riverine flooding limited to parklands and the yards of shoreline properties.

East of Cumberland Village (Boisé Village, Morin Rd): Elevated conditions are expected to remain, with possible decrease later in the week. Local access issues will remain along Boisé Lane.

South Nation Conservation (SNC):

Clarence-Rockland (Voisine Road and Old Highway 17): Elevated conditions are expected to remain. Low-lying areas near the river may continue to be impacted.

Ministry of Natural Resources (MNR):

Hawkesbury: Elevated conditions are expected to remain. Shoreline properties and parks may still be affected.

Residents in flood prone or low-lying areas, historically susceptible to flooding, should take the necessary precautions to protect their property. Please ensure:

• Sump pump is clear, in good working condition and has a backwater valve on it.
• Easy access to portable backup generator and pump.
• Downspouts are clear and the outlet is at least 3 m from the dwelling.
• Driveway culverts are clear of debris and drain well.
• Securing items that might float away as flows increase.

Additional Information

The Mississippi Valley, Rideau Valley, and South Nation Conservation Authorities continue to monitor conditions alongside the Ministry of Natural Resources and under Ontario’s Flood Forecasting and Warning Program. Updates are provided as conditions change.

For current Ottawa River conditions and forecasts, visit: https://ottawariver.ca/conditions/

For provincial flood warnings, visit: www.ontario.ca/law-and-safety/flood-forecasting-and-warning-program

This FLOOD WARNING is in effect until May 9, 2025, at 5:00 PM.

South Nation Conservation

Kat Watson, Coordinator, Early Warning Systems and Watershed Plans
kwatson@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.