Safety around dams

Our booms and buoys

• We install booms above our larger dam structures in consultation with Transport Canada. Booms warn river users that the area is hazardous and to stay back. Booms are installed in May and removed in October. See an example of a boom in the photo to the right.

• We install buoys above our low-head or smaller dam structures in consultation with Transport Canada. Buoys warn river users that the area is hazardous and to stay back. Where river flows and river debris can cause damage, buoys are used instead of booms. See an example of a buoy on this page.

Our dam danger signs

• Our dams are marked by red and white danger signs. Obey all warning signs. Two examples of these signs are shown on this page.
• Portage signs mark the formal portage route around the dam. For information about portages, routes and access points, visit the Routes and Access Points webpage.

Fencing and barriers

• Fencing and barriers around dams and other water control structures are there for your protection. Always keep out of these areas. 

Compared to our larger multi-purpose dams, low-head or "run of the river" dams may not be as visible from upstream. Don't let their smaller size fool you - they are danger zones as well, and in fact, they are sometimes called "drowning machines".

Like larger dams, low-head dams can create an underwater recirculating current that is nearly impossible to escape. This current, know as a "boil", can be so strong that it may pull you under water, even while wearing a lifejacket. Never swim, walk on, fish, or boat near these dams.

Why are low-head dams so dangerous?

1. The water above the dam picks up speed as it is squeezed over the top of the structure.
2. Fast-moving water plunges to the bottom of the dam, forcing the water already there to the surface. Water continues to plunge over the dam and the cycle repeats itself.
3. This recirculating current is known as a "boil". Anything caught in it will be repeatedly forced under the water and back up again.

View an infographic showing this process (234KB PNG).

Our seven large dams serve two purposes: flood mitigation and flow augmentation. Dam operators may change how much water passes through a dam at any time - without warning - making the area downstream hazardous. A change in the amount of water released by a dam can have an impact for several kilometres downstream.

Check river flows

We have dozens of automatic water level gauges on rivers and streams at important locations throughout the Grand River watershed. The information from the gauges is relayed to our head office and is available on our website. The website is updated every hour, usually around the half-hour.

Stay off unmonitored frozen water bodies. Even though ice on rivers and reservoirs and near dams may look thick, there can be hidden dangers:

• Ice may be thin where the water current underneath is fast-moving.
• Dam operators may change how much water comes through a dam - without warning - making ice on the reservoir and river very unstable.
• In spring, melting ice leaves banks slippery, making it easy to slip into the very cold river.  As well, the banks can form a dangerous, thin 'ledge' of unstable ice.