What is a weir?
A weir, also known as a low head dam, is a structure across a river that causes river
water to back up and pool behind the structure. This build-up of water may be used
for power generation or recreation, but in Calgary, the purpose is to divert water
from the Bow River into a canal system that provides irrigation water for agriculture.
The weir performs an important task, but as a side effect it creates a powerful
recirculating hydraulic wave, known to rescue professionals as a “drowning machine.”
Where is the Calgary Weir?
The weir is located on the Bow River slightly downstream of the Calgary Zoo, Fort
Calgary, and the confluence with the Elbow River. It is slightly upstream of the
Inglewood Bird Sanctuary and Blackfoot Trail. The weir is visible from Memorial Drive
at Deerfoot Trail or from the pathway system.
What are the planned modifications?
By constructing rock structures below the weir, the water level
will be backed up to eliminate the deadly recirculation. The backed-up water will drop over a series of short swifts followed by
Using an existing small island below the weir, the river will be divided into two
channels: a gentle channel to the south (river right) and a more challenging channel
to the north (river left). Signage and design features will be used to encourage people
floating down the river to use the south channel. More advanced canoeists and
kayakers will be able to practice their skills on several waves on the north channel.
Fish will also be able to travel up and down both channels, and features will be
included in the area to allow school groups to learn about local ecosystems and to
enjoy recreational opportunities.
What will it look like when the modifications are complete?
When the weir modification is complete, it will look like a natural section of the river.
Most of the materials used to enhance the area will be underwater. The banks and
riparian areas will be replanted and landscaped to look like natural shoreline. The
entire revitalized weir area will complement the existing Pearce Estate Park
Interpretive Wetland and Sam Livingston Fish Hatchery facilities, which are on the
south shore of that section of the Bow River.
Why modify the weir?
The modifications will create a new river amenity that complements the surrounding
park amenities and eliminates the severe drowning hazard. It will improve fish and
wildlife habitat and continue to divert water for irrigation.
Who is paying for it?
The Province of Alberta built and owns the current weir. The weir needs to be
modified so it is safe and ecologically functional, while providing recreational
opportunities and a healthy environment for people and fish. The estimated cost of
the weir project is $6.4 million. The parties contributing to this cost are: the Province
of Alberta through the Alberta Lottery Fund ($3.4 million), The Calgary Foundation
($2 million), and The City of Calgary ($1 million).
What if I fall into the water?
Presently, a fall over the weir would almost certainly lead to death. Once the
modifications are in place, falling into the water above the weir will be like falling
into other sections of the Bow River. There will be areas of faster water separated by
slow, deep pools from which most people can easily swim or walk to shore. As on the
rest of the Bow River, all river users need to be aware of the hazards of falling in.
What about parking?
Most people using the revitalized weir area will simply be passing through on a longer
trip from some point upstream to a destination further downstream. The City of
Calgary is currently conducting a study of all possible parking and access options in
the area, in conjunction with other stakeholders and adjacent facilities and
What will happen to the pelicans?
Recently, pelicans have been congregating near the weir because fish cannot pass the
structure and are trapped there. For the birds, it’s an “all you can eat buffet.”
Modifying the weir will allow fish to easily move up and down the river, helping them
to flourish, and a healthy fish population is also good for pelicans! After the weir’s
reconstruction, rather than finding an unnatural concentration of pelicans in this
small area, it is likely that the pelicans will disperse further up and down the river.
When will the project be completed?
There are strict Fisheries & Oceans Canada guidelines on the time of year when
construction work is allowed in the Bow River. The current construction schedule is envisaged to start in July/August 2007 and be complete in the spring of 2008.