Regulated Areas: Frequently Asked Questions
A regulated area is any area within the UTRCA watershed where development activities may be prohibited under the Conservation Authorities Act Section 28 Regulation (Ontario Regulation 41/24: Prohibited Activities, Exemptions and Permits), due to a natural hazard (flooding or erosion) or other regulated feature (wetland or the area surrounding a wetland). Hazardous land could be unsafe for development because of naturally occurring processes associated with flooding, erosion, or unstable soil or bedrock.
Regulations are based on standards set by the Province of Ontario and were established to:
- prevent loss of life,
- minimize property damage and social disruptions,
- reduce public and private expenditures related to emergency operations, evacuations, and restoration, and
- minimize the hazards associated with development in flood plains and areas that are susceptible to erosion, which may require expensive protective measures in future years.
There are exceptions for certain low-risk activities. Applicants are encouraged to confirm exceptions with UTRCA before carrying out the work.
Municipalities also have a responsibility under the Planning Act to direct development away from natural hazards through Official Plans and Zoning By-Laws. The Conservation Authority’s Regulation is also applicable under the Building Code Act.
A flood plain is the area near a watercourse that has been, or may be, subject to flooding. Within this area, people and property are exposed to risks from flooding.
For regulatory purposes, the Province approves a “flood event standard” that is used to define the limits of the flood plain. The flood event standard for most conservation authorities in southwestern Ontario is Hurricane Hazel. However, in 1989, the Province approved the UTRCA’s application to use the April 1937 Thames River Flood as the regulatory flood event standard for this watershed. This flood is considered less severe than Hurricane Hazel and is deemed equivalent to a 250-year storm event or a flood with a 0.4 percent chance of occurring in any given year.
Erosion occurs when soil is gradually washed away by water through a variety of processes like surface runoff and bank erosion. The loss of land can create an erosion hazard resulting in serious risk to people and property. Erosion hazards in the UTRCA watershed are associated with steep slopes, valley lands, and meander belts along river systems.
Wetlands are important natural features for their role in flood control, water filtration, groundwater recharge, and wildlife habitat. Wetlands are defined in the Conservation Authorities Act as land that:
- is seasonally or permanently covered by shallow water,
- has a water table close to or at its surface,
- directly contributes to the flow of water through a connection with a surface watercourse,
- has saturated soils that were formed by the presence of abundant water, and
- has vegetation dominated by water-loving or water-tolerant plants due to abundant water.
Wetlands are regulated due to their flood control function and the risk of unstable soils. The area surrounding a wetland is where development could impact its function.
The UTRCA uses field surveys, digital imaging, provincial datasets, geographic information systems (GIS) analysis, and computer modeling to identify regulated areas (flooding and erosion hazards, wetlands, and the area surrounding wetlands). Technical guidelines outlined by the Province are also used when determining flooding and erosion hazards limits. Mapping showing the approximate regulation limit is then created to support the text of Ontario Regulation 41/24. This mapping is used as a preliminary screening tool by the UTRCA and its municipal partners to determine if a property or given boundary is within the regulated area.
Regulated features and hazards do not need to be mapped to be regulated. The text of Ontario Regulation 41/24 determines the areas that are regulated and supersedes any mapping.
If your property is within a regulated area, please contact the UTRCA before beginning any construction or alterations to the site. Staff will work with you to determine the best course of action for your property by reviewing natural hazard limitations. In some cases, a permit may be required. Permitting questions can be directed to [email protected].
The flood plain is a natural hazard and is not registered on the title of a property.
Individual homeowners, potential buyers, and professionals acting on behalf of a potential buyer (lawyer, real estate professional) may submit a property inquiry to the UTRCA for a fee. The UTRCA will provide a report indicating if there is a regulated area on the property. Please contact [email protected].
Screening areas indicate where Ontario Regulation 41/24 is likely to apply and where further investigation of natural hazards and /or wetlands on a property may be needed. They are used as a tool to assist the UTRCA when assessing proposed development. This information is currently in DRAFT form and is under peer review. Please contact the UTRCA for more detailed information at [email protected].
Pre-consultation with the UTRCA is an important early step in any development. For a proposed development within or near a screening area, please contact the UTRCA Environmental Planning and Regulations staff at 519-451-2800, and the City of London Development Services Department at 519-661-CITY (2489), to schedule a joint meeting.
In making decisions on development through both its municipal plan review and Section 28 processes, UTRCA staff will assess proposals on a case-by-case basis, while considering the cumulative impact on the watershed. Considerations will include:
- The provision of safe or dry access for the development;
- The nature of the proposed development/intended land uses. Some land uses are considered sensitive land uses and may be restricted in areas subject to flood and erosion hazards (e.g., institutional uses, essential emergency services, and uses associated with the manufacture, disposal, treatment or storage of hazardous substances);
- The use of the property, expanding existing uses versus new development proposals;
- Ensuring that proposed development, including mitigation/floodproofing, does not impact upstream or downstream flood levels;
- Appropriate floodproofing measures;
- The maintenance of channel capacity and channel conveyance functions;
- Changes in flood storage characteristics.
This list is not intended to be exhaustive but represents the typical technical data. Typically, a precautionary approach is taken in making decisions on development on a case-by-case basis, which cumulatively and incrementally may have an impact on the resources of the watershed.
A comprehensive review and update of the UTRCA’s regulatory modelling and mapping is underway. Most of the original hazard mapping was completed 20 to 40 years ago and there are many advances in technology, physical changes to the watershed, and new data since then. This important process enables the UTRCA to use the most up-to-date information to assess risk.
Updates to natural hazard maps ensure the UTRCA uses the best available information to assess risk to people and property, consider mitigation measures and determine the potential impacts on development proposals. New hazard mapping information will also benefit municipal emergency management and infrastructure planning processes.
Updating hazard mapping for more than 2,000 km of watercourses in the UTRCA watershed is a complex process that uses a range of data inputs, including:
- Elevation data (from air photo interpretation, LiDAR, field surveys),
- Land use (from air photo interpretation),
- Impervious surfaces (i.e., pavement, buildings, roads, etc. where water cannot soak into the ground),
- Observed stream flow and precipitation data,
- Size and description of culverts and bridges,
- Watercourse cross-sections, profiles, and attributes.
Field data collection is a major component of this project, and involves:
- More than 130,000 elevation points on over 12,000 watercourse channel cross sections to supplement digital elevation models,
- More than 35,000 data points on 3,000 bridges and culverts.
Flood plains are first modelled and then mapped using detailed calculations, including how much water comes off the landscape (hydrology) and how water moves through the watercourse (hydraulics). Water surface elevations are used with ground elevation information to map the areas affected by the flood hazard.
Erosion hazards are mapped using high-resolution elevation data and Geographic Information System (GIS) models that enable the UTRCA to define the regulated valley. Data from the Province of Ontario and GIS models are key in determining the extent of wetlands and the areas surrounding wetlands that are regulated.
The UTRCA’s modelling and mapping are undergoing peer review by experienced professionals to ensure they are consistent with best practices and confirm the best available information is used appropriately. Peer review is an important step in ensuring that the analysis meets industry and regulatory standards.
Once peer review for each section of the draft mapping is completed, watershed residents and interested parties will be invited to provide feedback in-person and on-line.
The UTRCA expects to roll out the draft hazard mapping in multiple stages:
- Thames River reaches, including the North Thames River (Mitchell Dam to Forks in London), South Thames River (Pittock Dam to Forks), and downstream Thames River (Forks to Delaware),
- Groups of urban or partially urban subwatershed(s),
- Groups of primarily rural subwatersheds.