The Grand River Conservation Authority (GRCA) has issued a Flood Watch for parts of the Grand River watershed, including the Nith River and the lower Grand River, as a series of fast-moving weather systems bring warmer temperatures and rain to Southern Ontario.
The Flood Watch and accompanying Watershed Conditions Statement – Flood Outlook, first issued on Tuesday, January 6, remain in effect and are expected to continue until at least midday Monday, January 12.
According to the GRCA, the first system is expected to move through the region on Thursday, January 8, followed by another on Friday, January 9. Forecasts call for 10 to 15 millimetres of rain on Friday, along with temperatures rising into the low double digits above freezing. A third system is expected to arrive Saturday, January 10, bringing colder temperatures and a mix of ice pellets and snow.
Snowpack levels throughout the watershed are currently at or above normal for this time of year. Recent GRCA measurements show between 30 and 80 millimetres of water content stored in the snow. When combined with rain and warmer temperatures, this snowmelt is expected to increase runoff into local waterways.
A Flood Watch has been specifically issued for the Nith River in New Hamburg and Ayr, where higher flows and runoff could increase the risk of flooding in low-lying areas that are typically prone to water issues. The GRCA warns that as ice breaks up and moves through the river system, there is also a risk of ice jam formation, which can cause water levels to rise rapidly with little warning.
Flood concerns remain for the Grand River through Brantford, where water levels are already elevated due to existing river ice. The GRCA has also issued a Flood Watch for Brant County, Six Nations of the Grand River, Cayuga, Caledonia, and Dunnville. Ice movement combined with increased runoff could raise water levels throughout the lower Grand River, particularly in areas known for ice jam activity.
Municipal flood coordinators across the affected communities are being advised to closely monitor conditions and take necessary precautions, especially in locations historically vulnerable to flooding.
To help manage increased runoff and reduce downstream flooding, the GRCA says major reservoirs — including Belwood, Conestogo, Guelph, Luther, Woolwich, Laurel, and Shade’s Mills — will continue to be actively operated.
The public is being urged to exercise extreme caution around rivers and streams during this period. High flows and unstable ice conditions pose significant safety risks, and residents are reminded to stay off ice-covered water bodies. Parents are also encouraged to keep children and pets well away from watercourses.
The GRCA says river conditions and forecasts are being monitored closely, and additional flood messages will be issued if conditions change.