An owner’s guide to removing small dams in Ontario

Numerous small dams in Ontario were built many decades ago and they no longer serve a useful purpose today. In other cases the cost of continued maintenance or replacement makes the dam no longer practical. If you own a dam like this, you may decide you would like to remove it, either partly or completely.

What is a dam?

In Ontario, the governing legislation for dams is the Lakes and Rivers Improvement Act (LRIA). The LRIA defines a dam as “a structure or work forwarding, holding back or diverting water.” Approval is required to construct or decommission a dam that holds back water in a river, lake, pond or stream to raise the water level, create a reservoir to control flooding or divert the flow of water. Decommissioning means the full removal of the dam and its associated structures as well as partial removal or lowering the height of the dam.

Why should you consider removing your dam?


  • To protect the safety of the public. The sudden or unexpected failure of a dam may result in injuries or even loss of life.
  • To prevent property damage. If a dam is very old or has not been properly maintained, it may suddenly fail and cause damage to your property or; to downstream landowners, public roads, bridges or utilities.


  • To eliminate maintenance costs. Paying to keep an unnecessary dam in good repair can be eliminated by removing your dam.
  • To avoid future liability. If a dam fails, the owner may be liable for any resulting injury, death or property and environmental damage.


  • To create a healthier fishery. Depending on the type of fish in the stream, it may be impossible for them to get past the dam to reach their traditional spawning grounds. A shallow headpond may not offer suitable habitat for some fish species. Dam decommissioning can restore, create and enhance habitat for species at risk.

To improve the water quality

  • A shallow headpond may be the result of accumulated sediments. Removing the dam will restore the natural flushing action of the river or stream.


  • Recreational and aesthetic benefits. After a dam has been removed, the natural shoreline will gradually be re-established. The naturalized shoreline will create other outdoor and recreational opportunities.

Approvals required

It is the responsibility of the dam owner to obtain any necessary approvals before commencing the partially or complete removal of the dam.

If you wish to remove all or part of any dam in Ontario, you will need permission from the ministry. In some cases, you may also need approval from one or more of the following:

  • Fisheries and Oceans Canada
  • Transport Canada
  • Your local Conservation Authority
  • Ontario Ministry of the Environment, Conservation and Parks
  • Ontario Ministry of Tourism, Culture and Sport
  • Your municipality

The ministry can provide guidance to help you through the approval process. However, it is often more beneficial to hire an experienced consultant who can compile all the detailed information you will need to submit when you apply for approval.

The removal process

If you are considering removing your dam, you will need to do the following:

  • Understand: Evaluate the usefulness of the dam, its condition and its effect on the ecological value of the stream or river and on nearby land.
  • Plan: Be clear about what you hope to achieve by removing the dam. Talk to neighbouring landowners, local residents or parties that might be affected by the removal of the dam.
  • Assess your plan: Determine the problems that you might expect during dam removal and that might be caused by removing the dam. Adapt your plan to address such issues as timing, sediment control measures, disposal of material, stabilization of banks, or site restoration.
  • Get approval: Contact your district office and the other agencies listed above to determine if their approval is required prior to commencing work. Your local ministry office will advise you if any other agencies need to be consulted.
  • Communicate: Let people know of your definite plans, including time and date, before starting work.
  • Remove the dam: Choose a qualified and experienced contractor to do the work. Work should be carried out in accordance with the approvals obtained and that all conditions of the approval must be met.
  • Monitor: After the dam has been removed, monitor the site and observe the changes that have taken place. Habitat and environmental changes may occur slowly.

Not all dams should be removed

Some dams may still provide important societal benefits such as hydropower production or the headpond may cover underwater works such as water lines and utility cables. The dam may also provide important habitat for species at risk and other fish and wildlife, as well as recreation benefits. The dam may act as a barrier to the movement of sediment downstream or to undesirable fish or invasive species upstream.

If you decide not to remove your dam, you must still continue to inspect it regularly and make any necessary repairs to ensure the dam is safe.

For more information on this subject, please contact your local ministry district office or please follow the link to visit the Dam Decommissioning and Removal Technical Bulletin Dam decommissioning and removal.