As part of the delivery of programs and services related to natural hazards, Conservation Halton develops natural hazard and wetland mapping, policies, and technical guidelines. Through the process of developing these products, we engage with the people who live, work and/or have an interest in our watersheds, including residents, landowners, Indigenous communities, developers and municipal and provincial partners. We provide opportunities for people to offer feedback on our programs and services through public engagement on specific studies or initiatives as well as draft mapping, study findings and policies. Public involvement provides greater certainty and transparency on Conservation Halton programs and services, and we benefit from receiving observations about the watershed from the people who experience these watershed conditions.
Public Notice:
Conservation Halton is undertaking a study to update flood hazard modelling and mapping for the eastern reaches of Sixteen Mile Creek. The study area covers parts of Halton Hills, Milton, Mississauga, and Oakville. Click here to view a full-size version of the map and study area.
Conservation Halton regularly reviews and updates flood hazard modelling and mapping to fulfill the requirements of Ontario Regulation 686/21 and Ontario Regulation 41/24, under the Conservation Authorities Act.
Why Flood Hazard Mapping is Important
Flood hazard mapping is an important tool that supports Conservation Halton’s regulatory, planning, and flood forecasting and warning roles. This information also supports municipal emergency management planning, flood mitigation and infrastructure design, and helps property owners understand their potential exposure to riverine flooding.
Flood hazards include flood plains and spill flood hazards. A flood plain is an area of land that is flooded with water from a nearby creek or lake during large storms. Spills occur when flood waters leave the valley and floodplain and “spill” into surrounding lands, rejoining the watercourse at a distance downstream or moving into another watershed. Portions of the spill that are considered hazardous land (i.e., areas that could be unsafe for development because of flooding) are mapped as a spill flood hazard.
Get Involved
Have you observed flooding in the study area? Understanding your experiences helps us to fine tune our models. Your observations and comments are important to us. You are encouraged to share your feedback by February 27, 2026. Fill out our short feedback form to share your comments or to sign up to receive study updates.
Join Us
Register for a virtual public engagement session on November 27, 2025 at 7:00 pm to learn more about the study, ask us questions, and share your feedback.
Presentation material, as well as a recording of the public engagement session, will be available online for public review and comment until February 27, 2026. A second public engagement session to present draft, updated flood hazard mapping will be held in 2027.
This webpage will be updated as more information on this study becomes available. If you have any questions about this study, please email floodplainmapping@hrca.on.ca.
Conservation Halton is reviewing its policies related to development within natural hazards and wants to hear from residents and partners. Our survey to receive feedback on what Conservation Halton should consider when updating or developing new policies is now closed. For more information, please email policy@hrca.on.ca.
Background
Under Ontario Regulation 686/21, the Province requires Conservation Authorities to deliver programs and services related to understanding and managing natural hazard risks such as flooding and erosion, and to help prevent and/or mitigate these risks.
Conservation Halton reviews and makes decisions on permit applications for works in or near watercourses, flood plains or spill flood hazards, valleylands, wetlands, Lake Ontario’s shoreline, and places with unstable bedrock and soil. This is done under the Conservation Authorities Act and Ontario Regulation 41/24. The goal of this legislation and regulation is to protect people and property from risks related to natural hazards.
Conservation Halton is also responsible for reviewing and commenting on applications made under the Planning Act to ensure decisions are consistent with the natural hazard policies of the Provincial Planning Statement.
Conservation Halton is now conducting a review of its Board-approved policies that guide what may be permitted within regulated areas. The purpose of these policies is to help determine whether works proposed within regulated areas meet the tests of the Conservation Authorities Act (i.e., ensure development activity is not likely to affect the control of flooding, erosion, dynamic beaches or unstable soil or bedrock, or create conditions or circumstances that, in the event of a natural hazard, might jeopardize the health or safety of persons or result in the damage or destruction of property).