Flood Watch expanded to entire Rideau Valley due to lingering ice coverage

(WCS – R04/2025)

March 18, 2025 – The Flood Watch previously issued for parts of the Rideau Valley has been extended and expanded to include the entire watershed due to the risk of ice jamming as high temperatures and rising water levels continue to break up ice cover across the region. 

Although there is little precipitation in the forecast, Environment Canada and Climate Change is calling for warm temperatures this week, which will continue to melt the snowpack and increase water levels across the watershed. This can lead to potential ice jams, which can cause localized flooding as the backed-up water rapidly rises. 

Rising water levels and faster flows will continue to weaken ice cover throughout the week. Residents are advised to steer clear of shorelines as water levels may rise rapidly, and to stay off all ice. 

This Flood Watch statement is in effect until March 21, 2025 at 11:59 pm or until an update has been issued.

Weather Forecast: Environment and Climate Change Canada is forecasting above-freezing temperatures from March 18 to 21, with a high of 17 °C on March 19. 

Environmental Conditions: Water levels and flows across the Rideau Valley Watershed are stabilized and decreasing; however, they remain moderately elevated due to recent warmer weather, rainfall events, and significant snowmelt. Low-lying areas along the Rideau River and its tributaries are currently experiencing localized flooding and ice jamming. Some portions of the Rideau River and its tributaries are still partially covered in ice.

Risks: The entire watershed is under a flood watch, with the following risks present:

• The recent freeze-thaw cycle reduced the melting of ice on river bodies.As the temperature increases, the ice cover is expected to continue weakening and breaking up, creating a risk of ice jamming.
• The forecasted above-freezing temperatures will continue the snow and ice melt, potentially leading to increases in water levels and flows. Increasing potential for ice to mobilize and create ice jamming.
• Rising water levels and faster flows will continue to weaken ice cover, leading to hazardous conditions near lakes, rivers, and streams (slippery or unstable banks). Ice is unsafe for recreational activities, and shifting ice could pose risks to infrastructure.

Ice jams can form with little warning and cause a rapid rise in water level. Ice in a river or stream can pile up causing an ice jam. Water will back up behind the jam and can cause water to spill out of the river and flood surrounding areas. Although difficult to predict, ice jams tend to form in places where a river is shallow, or where it goes through twists and turns.

Location-Specific Considerations: 

Given the noted risk above, the Rideau systems and its tributaries are at risk of localized flooding. While the area of ice jamming cannot be predicted, watercourses covered with ice should be considered at a higher risk.

Residents in the City of Ottawa can check flood risks in their area using our Neighbourhood Flood Maps. If your property is within the RVCA watershed, use our Map your property tool to assess potential flooding impacts. Current water levels and stream flow with flood onset limits can also be consulted on our Interactive Map.

Action & Safety Recommendations: Residents in flood-prone areas are advised to closely monitor water levels and flows and take the necessary precautions to protect their property, such as:

• Ensuring sump pumps are clear, in good working condition, and have a backwater valve.
• Keeping a portable backup generator and pump easily accessible.
• Ensuring downspouts are clear and directing water at least 3 m away from the dwelling.
• Securing items that might float away as flows increase.
• Removing valuable items from basements or lower floors that could be subject to flooding.
• Keeping emergency phone numbers handy.
• Familiarizing yourself with your municipality’s Emergency Preparedness Plan.

Residents are reminded that a Water Safety Statement is in effect until April 15th and advised to exercise caution when near rivers, streams, and other waterbodies due to the risks described above. Parents should inform their children of these dangers and provide appropriate supervision.

Duration: This Flood Watch statement is in effect until March 21 at 11:59 pm or until an update has been issued.

RVCA monitors water levels and weather forecasts as part of its Flood Forecasting and Warning Program. Updates will be provided as conditions change.

Water Safety – High flows, unstable banks, melting ice or other factors that could be dangerous for recreational users such as anglers, canoeists, hikers, children, pets, etc. Flooding is not expected.

Flood Outlook – Early notice of the potential for flooding based on weather forecasts, calling for heavy rain, snow melt, high winds or other conditions that could lead to high runoff, cause ice jams and/or lakeshore flooding or erosion.

Flood Warning – Flooding is imminent or already occurring in specific watercourses or municipalities.

Flood Watch – Flooding is possible in specific watercourses or municipalities. Municipalities, emergency services and individuals in flood prone areas should prepare.