O. Reg. 41/24 applies to lands within the following areas as outlined in the Conservation Authorities Act and further described in the Regulation:

1. Hazardous lands,
2. Wetlands,
3. River or stream valleys,
4. Areas adjacent or close to an inland lake and that may be affected by flooding, erosion, or dynamic beach hazards, and
5. Other areas, including areas within 30 metres of a wetland.

Maps of regulated areas within the Upper Thames River watershed are available from UTRCA staff, at the Watershed Conservation Centre, and on UTRCA’s map website.

A permit is required from the UTRCA for the following activities within 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.

Hazardous land, as defined in O. Reg. 41/24, refer to land that could be unsafe for development because of naturally occurring processes associated with flooding, erosion, dynamic beaches, or unstable soil or bedrock.

Flooding occurs when a watercourse overflows its banks and spills onto adjacent low-lying land 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 in a floodplain can alter the flow of water and cause or worsen flooding elsewhere, increasing the risk to life and property.

The flood event standard for each conservation authority is set by the Ministry of Natural Resources (MNR) and outlined in the schedules of O. Reg. 41/24. It is used to define the flooding hazard for regulatory purposes and illustration on regulated area maps. The regulatory flood event standard for the UTRCA watershed is the historical observed 1937 flood on the Thames River. This flood is estimated to be equivalent to a 1:250-year flood, or a flood with a 0.4 percent chance of occurring in any given year.

The UTRCA flooding hazard was reduced in 1989 when the UTRCA and member municipalities requested a flood event standard reduction from Hurricane Hazel to the 1937 Thames River Flood.

In O. Reg. 41/24, river or stream valleys are described as areas having depressional features associated with a river or stream, whether or not they contain a watercourse. Rivers and stream valleys are continually being shaped by erosion and flooding, resulting in a loss of land which can endanger life and property.

A watercourse, as described in O. Reg. 41/24, refers to a defined channel, having a bed and banks or sides, in which a flow of water regularly or continuously occurs. Altering a watercourse can impact its ability to move water, resulting in flooding and erosion downstream.

A wetland, as defined by O.Reg. 41/24, is land that:

• is seasonally or permanently covered by shallow water or has a water table close to or at its surface,

• directly contributes to the hydrological function of a watershed through connection with a surface watercourse,

• has hydric soils (i.e., saturated soils), the formation of which has been caused by the presence of abundant water, and

• has vegetation dominated by hydrophytic plants or water tolerant plants, the dominance of which has been favoured by the presence of 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.

UTRCA staff determine the location and boundaries of individual hazards, such as flooding or river and stream valleys, 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 and an allowance is added to produce the regulated area. For more information, view the Regulated Area Map video.

Yes. Refinements to the extent of the regulated area may occur when new information (e.g., land use changes, bridge or culvert upgrades, new aerial photography, etc.) or analysis becomes available. As a result, additional regulated areas may be identified or previously identified areas may be modified or removed. The text descriptions in O. Reg. 41/24 override the mapping if there is a conflict.

If updates to the regulated area are significant, UTRCA will ensure that municipalities, interest-holders, and the public are notified of the proposed changes in accordance with requirements of the regulation.

The “Screening Area” overlay identifies areas where a study or map update is underway and may lead to proposed changes to regulated area maps. Further investigation of natural hazards on a property may be needed. There are currently two screening areas in the UTRCA watershed: Dingman Creek and the Thames River within the City of London.

The UTRCA provides publicly accessible Regulated Area Maps online and in-person at the Watershed Conservation Centre. UTRCA Regulations staff are also available to discuss property information by phone at 519-451-2800 or email at regulationsinquiry@thamesriver.ca.

If a property is regulated, individual homeowners, potential buyers, and professionals acting on behalf of a potential buyer (lawyer, real estate professional) may request a formal property inquiry from the UTRCA for a fee. The UTRCA will provide a written report with details regarding the regulated area on the property and site-specific mapping. 

When a map is updated, the extent of the regulated area might change. UTRCA Regulated Area Maps will help you determine if your property is affected by the regulation. If your property is in a regulated area, you will need to contact the UTRCA before proceeding with any construction or alterations on your property. Staff will work with you to understand your proposed project and determine if a conservation authority permit is required.

Pre-consultation with the UTRCA is an important early step in any project. Contact the UTRCA prior to beginning any construction or alterations on your property to 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.

Some homeowners have asked if the regulated area might affect property insurance or home values. The UTRCA is unable to offer advice on these issues and encourages landowners to contact their insurance provider, a qualified real estate professional, or the Municipal Property Assessment Corporation for guidance. Information can also be found at the Insurance Bureau of Canada.