Regulated Area Maps

Protecting People and Property and Supporting Safe Development

Ontario鈥檚 municipalities and conservation authorities work to protect people and property from natural hazards, including flooding and erosion hazards, as well as wetlands and the area surrounding them. The 糖心直播 (UTRCA) regulates development in or near natural hazards under the Conservation Authorities Act and . Proposed development in regulated areas may require a permit from the UTRCA.听

To illustrate the approximate location of the regulated area, the UTRCA develops maps that depict properties that may be affected by the regulation (O. Reg. 41/24). The regulated area maps are available online at and in-person at the Watershed Conservation Centre.听

Current Regulated Area Map Updates

The UTRCA is currently reviewing and updating regulated area maps starting with the City of London section of the Thames River. The City of London is also updating the regulatory floodlines for the Dingman Creek subwatershed. The public can view the draft maps and engagement opportunities at the links provided.

How are Regulated Area Maps Generated?听

The UTRCA determines鈥痶he鈥痩ocation and boundaries鈥痮f individual hazards,鈥痵uch as flooding hazards, through extensive data collection, statistical analysis,鈥痗omputer modelling,鈥痑nd鈥痸arious鈥痬apping techniques.鈥疶hroughout this process, staff follow technical guidelines prepared by the Ministry of Natural Resources and Conservation Ontario. 听

Using a Geographic Information System (GIS), the completed hazard layers are overlain,鈥痑nd an allowance is added to鈥痯roduce鈥痶he regulated area.听

Why update regulated area maps?

The UTRCA is undertaking a comprehensive review and update of its regulated area maps. Updating these maps is an important and ongoing process that enables the conservation authority and its municipal partners to use the most current information to identify hazards, assess risk, and guide land use decisions.听听

New data鈥痟as鈥痝reatly increased鈥痶he accuracy of鈥痟azard鈥痠dentification. Advances in computer technology鈥痑nd software鈥痟ave also improved the UTRCA鈥檚 ability to model and map hazard areas,鈥痚specially flooding and erosion hazards. Changes and refinements to the approximate regulated area may occur and additional regulated areas may be identified, or previously identified areas may be modified or removed.听听

The UTRCA will engage with member municipalities, the public, and other interest-holders as part of the update process to ensure compliance with the regulation.听Once the updated maps are approved by the UTRCA Board of Directors, they are听used in the administration of the听Conservation Authorities Act听and Ontario Regulation 41/24.

What Do the Layers on the Draft Study Area Map Mean?听

The UTRCA posts a draft study area map on when significant updates are required due to new information or analysis. The draft map is used for information and engagement purposes and does not inform development decisions until approved by the UTRCA's Board of Directors.听

The draft study area map shows the following layers or features:

  • Flooding Hazard听鈥� depicts the current flooding hazard for the 1937 Flood Event Standard (1:250-year return period flood).
  • Flooding Hazard Updates听鈥� identifies the draft flooding hazard for the 1937 Flood Event Standard (1:250-year return period flood), based on new information or analysis (e.g., elevation data, field surveys, etc.).
    • Flooding Hazard Limit听鈥� layer includes Flood Plain, High Ground 鈥� NO DRY ACCESS, and Other Buildings 鈥� Flood Hazard.
    • Flood Plain听鈥� depicts low-lying lands adjacent to a river, stream or small inland lake that have been or may be subject to flooding during a flood event (1:250-year return period flood). The regulated area allowance is calculated from the outer limit of this line.
    • High Ground 鈥� NO DRY ACCESS听鈥� depicts areas of high-ground (i.e., areas above the flood elevation) that would be surrounded by flood waters during the 1:250-year return period flood with no dry access to the property.
    • Other Buildings 鈥� Flood Hazard 鈥� depicts buildings that intersect the flood plain and are included in the flooding hazard limit and regulated area. More site-specific information is needed to determine flood hazard impacts on these structures.
  • River or Stream Valley听鈥� depicts the current river or stream valley.
  • River or Stream Valley Updates听鈥� identifies the draft river or stream valley based on new information or analysis (e.g., updated air photos, elevation data, etc.) to determine the projected stable top of slope.
  • Wetlands听鈥� depicts the most current wetland layer.
  • Regulated Area听鈥� represents the greatest extent of the combined current hazards or features plus an allowance as required in Ontario Regulation 41/24.
  • Draft Regulated Area听鈥� represents the greatest extent of the combined draft hazards or features plus the required allowance. There may be areas where the regulated area has expanded or reduced due to new information or analysis.

Note: Differences between the current and draft map layers reflect enhanced data quality, as the updated layers are based on more accurate and detailed information than before.听