Floodplain Mapping

Why Floodplain Mapping is Important

Conservation Authorities in Ontario have a legal mandate to ensure that development does not occur in areas that are that susceptible to flooding and erosion. Building in these areas can result in damage to properties when flooding or erosion occurs, and in extreme cases can result in loss of life. In Canada, floods account for the largest portion of disaster recovery costs on an annual basis.

The first step to reduce the cost of flood damage within a community, and to direct development way from hazards, is to have mapping that accurately shows the flood and erosion hazards.  These maps help people prepare for and respond to potential flooding and make informed decisions about their own emergency plans and property improvements. 

The maps are used for our Prohibited Activities, Exemptions and Permits Regulations (Ontario Regulation 41/24), and by staff when reviewing development applications. Floodplain mapping is also used by municipalities in preparing official plans and zoning by-laws, which guide future development in their jurisdiction.

Visit our Development Regulations and Plan Input and Review page for more information.

LRCA’s Role in Floodplain Mapping

Lakehead Region Conservation Authority (LRCA) is a watershed management agency.  Our goals include protecting our communities from natural hazards, conserving our natural environment, and supporting our partners in creating sustainable communities.  From a flood management viewpoint, LRCA and our municipal partners rely on floodplain mapping for:

  • flood forecasting and warning,
  • emergency planning and response,
  • prioritization and planning for flood mitigation work,
  • community planning and land use decision making, and
  • identifying the extent of the flood hazard.

Mapping is an important communication tool to illustrate areas affected by flood hazards, erosion hazards, wetlands, and the area of interference surrounding wetlands. These hazards are defined in text within regulations made under the Conservation Authorities Act. In the event of a conflict with the mapping, the text description prevails.

Floodplain Mapping Updates

Floodplain maps and studies are updated periodically as new data becomes available, such as topography and land use changes, and modelling techniques and software are improved.  Updated mapping that accurately illustrates the hazard lands is required to properly plan servicing, review development proposals and issue building permits. Planners, building officials and regulations officers utilize this mapping to determine where the regulations may apply. The LRCA must rely on the best available information to assess the risks due to flooding in applying their regulation. 

Between 2015 and 2020, the LRCA updated the floodplain maps in the following watersheds (click for fact sheets):

Additional resources:

For more information about floodplain mapping within the LRCA’s jurisdiction, please contact our office at (807) 344-5857.