A warm front accompanied by heavy rainfall moved into the Grand River watershed on Monday evening, and will persist through Wednesday. Temperatures associated with this weather system are forecast to reach 13 degrees late Tuesday afternoon and remain elevated overnight before declining rapidly through the day Wednesday. Rainfall totals of 20 to 30 mm have been received across the watershed over the last 24 hours, with an additional 20 to 25 mm forecast for the next 24 hours. The combination of warm temperatures and rainfall is beginning to trigger significant runoff into the river system.
These current weather conditions are melting the remaining snowpack across the watershed and resulting in very high flows in rivers and streams across the watershed. This will result in flows similar to those experienced during normal spring flooding. Ice jams currently in place in the Grand River through the City of Cambridge, City of Brantford and community of Cayuga have a high potential of causing additional flooding. A small ice jam is also in place downstream of the community of Plattsville on the Nith River. Ice jams in these areas have begun to show signs of erosion and it is anticipated that they will release during this event. Ice jams can form and release without warning and extreme caution should be used in areas where they are occurring.
Those who live in the areas identified in the floodplain map attached are strongly urged to evacuate. @BrantfordPolice are going door to evacuate the following streets Foster, Cayuga, Aberdeen, Strathcona, Pontiac, Tecumseh, Ontario, Port, Eagle Ave, Robertson, Denver and Baldwin pic.twitter.com/j5AkP734QT
— City of Brantford (@CityofBrantford) February 21, 2018
All GRCA reservoirs are being operated with storage available to manage runoff from this event which will help reduce downstream flooding.
Flood Warning
Entire Watershed: Risk of flooding exists in low lying areas and from ice jams as this event moves through the watershed. Snow melt, ice, and debris in small watercourses have the potential to create obstructions in ditches and culverts resulting in localized road flooding across the watershed. Residents in areas near waterways should be aware of rapidly changing conditions and take appropriate precautions.
Town of Grand Valley/Waldemar: The flood c-ordinator for Grand Valley/Waldemar should monitor conditions along the Grand River and close Highway 25 on Tuesday afternoon. This road will remain closed until river flows begin to recede on Thursday. Residents in affected areas should be warned as necessary.
Township of Mapleton/Drayton: The flood co-ordinator for Mapleton Township should monitor conditions along the Conestogo River and warn residents in the Level 1 flood zone. Current forecasts predict this area will begin flooding on Tuesday afternoon.
Township of Woolwich/St. Jacobs/West Montrose: Flood co-ordinators in Woolwich Township are asked to monitor conditions and maintain the closure of Three Bridges road. Woolwich Township flood coordinators are also asked to warn the trailer park in West Montrose and low-lying areas adjacent to the Grand River typically prone to spring flooding.
Township of Wilmot – New Dundee: Township of Wilmot staff are asked to monitor conditions downstream of New Dundee dam and warn residents as necessary.
City of Cambridge: City of Cambridge flood co-ordinators are asked to monitor conditions in the Blair area, adjacent to the Grand River, and the Speed River area downstream of the King Street bridge in Preston due to the potential of ice jam flooding in these areas. City of Cambridge staff are asked to report back if they observe any significant changes in this ice jam. City of Cambridge flood co-ordinators are also asked to monitor and close Blackbridge Road at the Speed River.
Township of Wilmot – New Hamburg: Township of Wilmot staff and Waterloo Regional police are asked to warn residents up to the Level 3 flood zone and monitor conditions. It is anticipated that flows through New Hamburg will peak overnight Tuesday.
Township of North Dumfries – Ayr: Township of North Dumfries flood co-ordinators are asked to warn residents up to the Level 3 flood zone and monitor conditions. It is anticipated that flows through Ayr will peak overnight Wednesday.
City of Brantford: City of Brantford flood co-ordinators are asked to maintain the closure of Gilkison Street and monitor ice jam conditions closely through the dike reach. Ice jams currently in place are expected to release with this event. Flows are anticipated to peak through Brantford on Wednesday afternoon.
Town of Cayuga: Haldimand County flood co-ordinators are asked to warn residents in the floodplain in the Town of Cayuga in anticipation of ice jam flooding as a result of this event. Flows are expected to peak through Cayuga overnight Wednesday.
Town of Dunnville/Port Maitland: Haldimand County flood co-ordinators are asked to monitor the mouth of the Grand River in Port Maitland as the Canadian Coast Guard continues icebreaking operations to reduce the potential for ice jams at this location. Flood co-ordinators should also warn residents in the floodplain. Flows are expected to peak on Thursday.
