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Floodplain Mapping

Conservation Authorities are responsible for floodplain management. Identifying lands that are vulnerable to flooding is an important responsibility for Ontario’s Conservation Authorities. Accurate engineered flood plain mapping is the foundation of effective flood plain management. In eastern Ontario, the 1:100 year flood plain is the regulatory standard calculated as having a 1% chance of occurring in any given year. Conservation Authorities use the mapping in the administration of regulations made under the Conservation Authorities Act.

What is a Floodplain?

Floodplains are low lying areas near watercourses that are naturally subject to flooding.

Why Map Floodplains?

Mississippi Valley Conservation Authority protects people and property from natural hazards. A natural hazard includes risks such as flooding and unstable slopes. The regulatory flood standard for the Mississippi Valley watershed is a 1:100 year flood event.

What is a 1:100 year flood?

A 1:100 year flood is a major flood that risks causing serious damage to people and property. These major floods have a 1% chance of occurring in any given year. To compare, a 50 year flood has a 2% chance of occurring in any given year. Simply because a major flood occurs does not mean that it cannot reoccur the next year.

How are Floodplains Mapped?

Floodplain maps are produced using a science-based method of field surveys and computer models. Background data is gathered on: land use; topography; stream flow; and precipitation. Field surveys collect information on local infrastructure (culverts, bridges, etc.). Data is then entered into computer models to calculate stream flow and water levels. Review of technical work and modelling is completed to finalize the floodplain map.

How are Floodplain Maps Used?

Floodplain maps establish protection areas to guide development projects to safe areas. Property owners may reduce the risk of flooding through options such as: raising building envelops; directing development outside of the floodplain, and using appropriate design. Mississippi Valley Conservation Authority works with property owners on solutions for their projects.


NOTE:  Effective April 1, 2024 all regulatory setbacks around regulated wetlands shall be 30 meters regardless of what is shown on these maps, per O. Reg. 41/24.
Updated mapping to comply with the new regulation will be completed by the end of 2024. If you have any questions, please contact our office at 613-253-0006.


Terms and Conditions

The information on the maps found on this webpage is not intended to constitute advice nor is it to be used as a substitute for specific advice from a conservation authority professional. You should not act, or refrain from acting, based upon information on these flood risk maps without independently verifying the information and, as necessary, obtaining professional advice regarding your particular facts and circumstances. These facts can be obtained by contacting the Mississippi Valley Conservation Authority office (MVCA) at or calling (613) 253-0006.

The Regulated Area on this map applies to river or stream valleys including their floodplains and slopes, as well as provincially significant wetlands of the MVCA jurisdictional area. This map will help you understand if all or part of your property is regulated by the MVCA.

In some cases, not all of the areas described above may be mapped, as some areas or details may be generalized and/or not yet reflect recent changes. It is important to know that the Regulation still applies, whether these areas are mapped or not. If you are unsure whether your property is regulated, contact the MVCA for more information.

If your property is within an area regulated by the MVCA and you want to do any construction work or development activities on it, you will need a MVCA permit. This is in addition to a building permit or other approvals from your municipality and other agencies.

By clicking I agree, you agree that you have read, understand, and accept the terms and conditions described in this disclaimer. If you do not agree to these conditions, you should not use the information shown on this website in any way.



MVCA owns and retains all right, title and interest in the intellectual property (“IP”) of the information contained in this website, or other parties that have licensed their material to the MVCA including the Ontario Geospatial Data Exchange (OGDE) and is marked as Copyright of the MVCA. All MVCA-owned IP generated from maps on this website (downloads or prints “Data”) must be marked as such.