A regulated area is any area within the UTRCA watershed where development, construction, and site alteration activities may be restricted under the Conservation Authorities Act due to the presence of a natural hazard. Natural hazards include flood and erosion hazards, watercourses, and valleys, as well as wetlands and the area surrounding them.

Structures and property in or near floodplains, slopes, and valleys may be susceptible to damage from natural processes such as flooding, erosion, and slope failures. These processes become hazards when people and property locate in areas where they normally occur.

A watercourse is a river, stream, creek, or open drainage channel. Altering a watercourse in any way can significantly impact its ability to convey water and may cause erosion.

Flooding occurs when a watercourse overflows its banks and spills into low-lying areas, which are known as floodplains. These areas act as a natural extension of the watercourse during times of high flow to transport and store excess water. Development or fill in a floodplain can alter the flow of water and cause or worsen flooding elsewhere. Similarly, allowing more people to live in floodplains increases the risk to life and property as well as public costs due to emergency response and cleanup.

Wetlands are 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 and the area surrounding them (30 metre buffer) are regulated due to their critical role in flood management as they store water and reduce downstream flows. Wetlands may also pose a risk to development due to the presence of a high water table or unstable soils.

Slopes can erode and collapse for a variety of reasons including increased weight on or near the slope, changes in grading or drainage, loss of vegetation, and erosion of the slope bottom.

River and stream valleys are regulated to protect their role in storing and conveying floodwaters and to prevent development on or near steep or unstable slopes.

Hazardous sites are lands that could be unsafe for development and site alteration due to unstable soils (e.g., organic soils, sensitive marine clays) or unstable bedrock (e.g., karst topography).

UTRCA staff determine the location and boundaries of individual hazards, such as floodplains or steep slopes, through extensive data collection, statistical analysis, modelling, and various mapping techniques. Throughout this process, staff follow technical guidelines prepared by the Ministry of Natural Resources and Conservation Ontario. Using a Geographic Information System (GIS), the map layers showing each hazard are overlain to produce the regulated area. The approximate regulated area shown on the map incorporates all the hazards in an area, including safety allowances as set out in provincial regulations.

Changes to regulated area maps might occur for a number of reasons, such as when new information is incorporated into the models or there are physical changes in the watershed. For example, new or expanded development or new or replaced infrastructure like bridges or culverts can alter the size of a regulated area. This means properties previously located outside of the regulated area could now be within it and vice versa.

The regulated area depicted on the maps is approximate and based on the best available information at the time of map production. A property may contain natural hazards that are not identified on the current regulated area maps but would still be subject to regulation.

To determine if your property is affected by a regulated area, you can access UTRCA’s regulated area maps at maps.thamesriver.on.ca. Type your address in the search bar located on the right of the screen to view a map of your property. If your property is within a regulated area, it does not automatically mean you are in a floodplain. A property can be regulated for many reasons, and our staff can help you understand the basis for it.

If your property falls within a regulated area it means that there are one or more natural hazards located on your property. Before beginning any construction or alterations on your property, please contact the UTRCA. Staff will work with you to understand your proposed project and determine if a conservation authority permit is required.

You may require approval from the UTRCA for the following activities in or near a regulated area:

• constructing, reconstructing, erecting, or placing a building or structure of any kind,

• any change to a building or structure that would have the effect of altering the use or potential use of the building or structure, increasing the size of the building or structure, or increasing the number of dwelling units in the building or structure,

• site grading,

• temporarily or permanently placing, dumping or removing any material originating on the site or elsewhere,

• straightening, changing, diverting, or interfering in any way with the existing channel of a river, creek, stream, or watercourse (all watercourses in the watershed),

• changing or interfering with a wetland in any way.

The minimum standard for flood protection in Ontario is the 1:100 Year Flood Event. However, many conservation authorities are legally mandated to require a higher level of flood protection based on local historical flood events. In 1989, the Ministry of Natural Resources approved the UTRCA’s application for a Regulatory Flood Event Standard reduction from the 1954 Hurricane Hazel event that hit Toronto to the local 1937 Thames River flood. The 1937 Thames River flood event is considered equivalent to a 1:250-year flood event or a flood with a 0.4 percent chance of occurring in any given year. The 1937 Thames River flood is the flood hazard shown on the UTRCA's regulated area maps.

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 519-451-2800 to talk to UTRCA staff.

Pre-consultation with the UTRCA is an important early step in any project. Contact us before beginning any construction or alterations on your property. UTRCA staff will work with you to understand your proposed project and determine if a conservation authority permit is required.

Before contacting the UTRCA, please have the legal description of your property (e.g., municipal address, lot and concession, plan or block number) and/or a location map. The UTRCA can also provide written confirmation and a detailed review of how your property is affected by the Conservation Authorities Act and Ontario Regulation 41/24 (fees may apply). If you have questions, call UTRCA staff at 519-451-2800.

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.

The UTRCA is undertaking a comprehensive review and upgrade 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.

To begin the complex process of upgrading hazard information for the entire watershed, the UTRCA needed new, more detailed data, which came from:

• new high-resolution remote sensing (digital elevation) data,

• updated aerial photography,

• improved modelling hardware and software,

• field surveys of watercourses, bridges, and culverts.

The new data has greatly increased the accuracy of hazard identification. Advances in computer technology and software have also improved our ability to model and map hazard areas, especially flood and erosion hazards.

Once draft maps of the regulated area are completed for a portion of the watershed, a peer review by experienced professionals is initiated to ensure the maps meet industry and regulatory standards. Municipal partners, watershed residents, and interested parties are provided with an opportunity to review the draft maps.

UTRCA staff reference regulated area maps when reviewing development applications to determine if a property may contain hazards and if a permit is required under the Conservation Authorities Act.

The UTRCA’s member municipalities use the regulated area maps when reviewing development proposals under the Planning Act and Building Code, updating Official Plans and Zoning By-law schedules, and undertaking infrastructure and emergency management planning.

Anyone can view these maps to determine if the property they own or want to purchase contains natural hazards and if a conservation authority permit may be required for any development or activities.