April 17^th, 2026 – This FLOOD WATCH statement is an update to the Flood Watch issued for areas along the Lower Ottawa River (Arnprior to Hawkesbury) on April 16^th, 2026.      
    
Water levels and flows have been gradually increasing along the main stem of the Ottawa River due to recent rainfall combined with snowmelt in the Ottawa River Basin. Levels and flows are expected to continue to increase over the weekend.
 
From Arnprior to Britannia, minor flood levels are expected to be reached in flood prone areas today, with the potential for major flood levels to be exceeded in some locations over the weekend.
 
Downstream of Britannia to Hawkesbury, minor flood levels will likely be exceeded on Sunday in flood prone areas, with the potential for major flood levels to be exceeded in some locations starting Monday.
 
The minor flood level is defined as the level at which parts of some streets, lawns and parks are beginning to flood, with no or few houses/buildings being affected.
 
The major flood level is defined as the level at which one or several streets are beginning to flood, with several houses/buildings or neighbourhoods being affected.
 
Water levels are currently expected to remain well below historical flood levels on the main stem of the Ottawa River. 
 
This advisory includes the following impacts in flood prone areas along the Ottawa River:
 
Fitzroy Harbour to Shirley’s Bay
Water levels in the Constance Bay area are currently at the 2-year flood event level and are expected to rise up to 40-50 cm over the next 3-5 days. Residents can expect flooding in low-lying and flood prone areas. No impacts to roadway access are anticipated.
 
Grandview to Britannia
Water levels are expected to rise by 30-40 cm over the weekend and may result in nuisance flooding of low-lying areas, including residential yards and parkland. At this time, impacts are expected to remain largely limited to yard-level encroachment, with no widespread impacts to structures or roadway access anticipated.

Petrie Island to Cumberland
Water levels are expected to rise by up to 50 cm over the weekend and may result in flooding of low-lying roadways, parkland, and adjacent properties. In some areas, water on roads may limit access. A small number of low-lying properties may experience water approaching residential structures.
 
City of Clarence-Rockland to Hawkesbury
Water levels are expected to rise by up to 45 cm over the weekend and may result in flooding of low-lying roadways, parkland, and adjacent properties. In some areas, water on roads may limit access. A small number of low-lying properties may experience water approaching residential structures.
 
Residents in flood-prone areas are encouraged to closely follow changing conditions and to take necessary measures, such as:

• 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.

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 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/page/floods
 
This FLOOD WATCH is in effect until April 27^th, 2026 at 5:00 PM.
An update will be issued on Monday, April 20^th, 2026

South Nation Conservation
Phillip Dagenais, Water Resources Specialist
(613) 984-2948 | pdagenais@nation.on.ca 
 
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.

• Flood Warning: flooding is imminent or occurring within specific watercourses
  and municipalities.