Flooding

One of our most important strategic priorities is protecting life and minimizing property damage from flooding and erosion.

The Grand River system has a long history of flooding. Floods can occur in all seasons: during the spring melt, following major rainstorms in summer and fall, and during a rapid melt or because of an ice jam in the winter. You can see historical flooding photos on our Flickr page.

We manage flood risk by:

• monitoring weather conditions and river flows to know when flooding is possible;
• issuing flood messages to alert municipal flood coordinators and the public about coming high water;
• operating seven dams and reservoirs to hold water and reduce flood peaks;
• owning and maintaining dikes to protect low-lying areas in Kitchener (Bridgeport), Cambridge (Galt) and Brantford; and
• regulating development in flood-prone areas to reduce potential property damage.

Floodplain mapping updates

Under the Conservation Authorities Act and Ontario Regulation 41/24, the Grand River Conservation Authority regulates development activities in natural hazards, including the riverine flooding hazard (commonly referred to as the floodplain). Limiting development in floodplains is central to our strategic priority to protect life and minimize property damage associated with flooding. In the Grand River watershed, a floodplain is determined based on the greater of the Hurricane Hazel storm event (the Regional storm) or the 100-year return period flood. The flood produced through these calculations is called the Regulatory Flood, the limits of which define the extent of the riverine flooding hazard. 

New modeling tools and techniques, more detailed topographical data and updated climate data are some of the reasons that result in updated floodplain mapping. Information on studies underway that include floodplain mapping updates can be found at the links below.

2025 Lower Conestogo Floodplain Mapping Update 

Subwatershed Studies

Subwatershed studies may include the development of, or updates to floodplain mapping.  Please visit Current studies page for details on current studies underway.  

Flood warning system

Learn more about our flood messages and how you can receive them directly on our Flood warning system page.

Preparing for floods

Learn how what you can do to deal with floods on our Preparing for floods page.

More information

View our Flood resources page to read brochures and visit other websites to learn more about flooding.