GRCA Flood Message #3: Flood Warning UPDATE
The Grand River Conservation Authority is issuing the following Flood Warning message for the entire Grand River watershed. This message updates Flood Message #2.
The weather system that has been affecting much of the province since Friday continues to impact the Grand River watershed with significant rainfall resulting in much higher river flows than previously forecast. Rainfall totals of more than 75mm have been recorded in parts of the watershed with an additional 10-20mm of rain expected overnight Saturday.
Forecasting this event has been a challenge due to the uncertainty surrounding how the precipitation would transition between rain and freezing rain on Saturday. Temperatures have remained above freezing throughout much of the watershed resulting in more rain and higher amounts of runoff into local waterways and more significant flooding than previously forecast.
Northern Grand River Watershed
As much as 75mm of rainfall has fallen across the northern Grand River watershed resulting in higher than expected river flows through Drayton and Grand Valley.
Grand River (Grand Valley)
Flows in the Grand River through Grand Valley have resulted in the closure of Highway 25. Flows are forecast to peak in the 250 cm/s (cubic metre per second) range overnight Saturday. These flows are similar to those experienced in June 2017. Flood Coordinators have been asked to notify residents in Flood Warning Zone 2 and continue to monitor conditions closely.
Grand River (Waldemar)
Flows in the Grand River through Waldemar are forecast to peak in the 350 cm/s range overnight Saturday. These flows are similar to those experienced in June 2017. Flood Coordinators are asked to monitor conditions along 10th Line between Waldemar and Grand Valley and arrange closures as necessary.
Conestogo River (Drayton)
Flows in the Conestogo River through Drayton are forecast to peak in Flood Warning Zone 3 through the evening on Saturday. These flows are similar to those experienced in June 2017. Flood Coordinators have been asked to warn residents in Flood Warning Zone 3 and continue to monitor conditions closely.
Central Grand River Watershed
The central portion of the Grand River watershed has received between 40-60mm of rainfall through the day on Saturday, causing flooding in the communities of West Montrose, St. Jacobs, New Hamburg, Ayr and Cambridge.
Grand River (West Montrose)
Flows in the Grand River through West Montrose are expected to peak in Flood Warning Zone 2 early Sunday morning. Woolwich Township Flood Coordinators have been requested to notify residents in this area and monitor conditions.
Nith River (New Hamburg)
Flows in the Nith River through New Hamburg are expected to reach Flood Warning Zone 3 mid-morning on Sunday. Wilmot Township Flood Coordinators have been requested to notify residents in affected areas and monitor conditions.
Nith River (Ayr)
Flows in the Nith River through Ayr are expected to reach Flood Warning Zone 3 early Monday morning. North Dumfries Flood Coordinators are requested to notify residents in affected areas and monitor conditions.
Nith River (Wolverton)
Flows in the Nith River through Wolverton are expected to be similar to those experienced during February 2018, peaking around 300 cm/s early Monday morning. Oxford County Flood Coordinators are requested to notify those residents affected during the February 2018 flood event.
Southern Grand River Watershed
Communities along the Grand River through the southern watershed including Paris, Brantford, Caledonia, Cayuga, and Dunnville should prepare for flooding similar to levels experienced in June 2017. More detailed information for Flood Coordinators in the southern watershed will be provided in flood warning messages on Sunday.
Entire Grand River Watershed
Watershed flood coordinators are asked to continue to monitor all previous closures and conditions outlined in Flood Message #2.
GRCA’s major reservoirs at Belwood, Conestogo, Guelph, Luther, Woolwich, Laurel, and Shade’s Mills are being used to manage runoff from this event and reduce flooding downstream of these reservoirs. Once rainfall has ended, river flows will remain high through much of next week as water is released from reservoirs and they are returned to their normal operating levels for this time of year.
The public is reminded to exercise extreme caution around all water bodies. Banks adjacent to rivers and creeks are very slippery at this time and, when combined with current weather conditions, pose a serious hazard. Parents are encouraged to keep their children and pets away from all watercourses.
This message will be updated by 3:00 p.m. on Sunday January 12, 2020. Updated flood messages will be issued as conditions develop and better forecast information becomes available.