Dams, Water Crossings, and Channelization

The Ministry of Natural Resources is committed to protecting the public health and environmental safety of Ontarians by enhancing regulatory requirements for the safe management of dams. The Water Resources Section protects the public against dam failure through the development of policies, standards, guidelines, education, and training.

Dams, Water Crossings and Channelization

Dams are barriers constructed in a lake or river to hold back water to raise water levels, create a reservoir to control flooding, or to divert water. To reduce the possibility of water overtopping or overflowing a dam, discharge facilities can be opened to release the excess in a safe manner.

A water crossing is any bridge, culvert or causeway that is constructed to provide access between two places separated by water. It can also hold back, move forward, or divert water.  Channelization refers to a river that has been changed, re-aligned, deepened, or had its bed or bank material changed.

Dams as Hazards

The human caused hazards associated with dams include their threat to public and riparian rights, the environment, persons and property. 

The main causes of dam failures are:

• Flooding from heavy runoff 
• Flooding caused by upstream dam failure
• Earthquakes
• Landslides
• Misoperation or human error

The Lakes and Rivers Improvement Act

The Water Resources Section helps protect against these hazards through legislation, policies, standards, and guidelines to ensure dams are suitably located, constructed, operated and maintained.  The most important legislative tool used to do this is the Lakes and Rivers Improvement Act (LRIA) and its associated regulation on dam construction.

The LRIA currently requires dam owners to obtain MNR approval of new dams and repairs or alterations to existing dams.

The Water Resources Section has been working with a stakeholder advisory panel on enhancements to Ontario’s current dam safety program that will serve to strengthen the safe operation and management of dams in Ontario.