Natural systems such as flood plains are regulated under the Conservation Authorities Act and implemented by local conservation authorities.
- Conservation authorities create flood plain maps based on the applicable ‘design flood’ event standard established by the Province. In Eastern Ontario the design event is the 100 year storm. This is the event that has a one per cent chance of occurring in any year.
- Mapping is reviewed every five years and updated on an as needed basis.
- A permit from the conservation authority is required prior to any development or site alteration within the flood plain.
- Development is prohibited where flooding may compromise the ability to deliver essential services, where flooding may cause unacceptable risk of property damage, or where chemical, hazardous or toxic substances could contaminate potential flood waters.
In order to reduce the potential for public costs, risk of injury, loss of life, property damage, or economic or social disruption that may result directly or indirectly from development and other activities in flood plains, municipalities also incorporate the flood plain mapping produced by the conservation authorities into their Official Plan policies (Section 4.8.1) and Zoning By-law policies (Section 58).
The City’s Official Plan separates flood risk areas into two categories: Flood Plain, and Two-Zone Flood Plain: Floodway and Flood Fringe. Each of these categories contain specific policies for the regulation of development. Two-zone flood plain areas may permit a wider range of development than Flood Plain areas, where flood risk is reduced due to flood mitigation infrastructure or other similar features.