Wizard Lake Weir

What is a weir?

A weir is a small overflow dam used to alter the flow characteristics of flowing water (i.e. out flow of a lake). In most cases weirs take the form of a barrier across the out flowing water that causes water to pool behind the structure (not unlike a dam), but allows water to flow over the top. Weirs are commonly used to alter the flow regime of water and prevent flooding.

WizardLakeWeir

The Wizard Lake weir was constructed to regulate the levels of the lake (similar to many other lakes and weirs in the Province) and to control the headwaters flowing into Conjuring Creek; this weir is also equipped with a fish ladder.

What is a fish ladder?

A fish ladder is a structure on or around artificial barriers to facilitate fishes' natural migration. They enable fish to pass around the barriers by swimming and leaping up a series of relatively low steps into the waters on the other side. The velocity of water falling over the steps has to be great enough to attract the fish to the ladder, but it cannot be so great that it washes fish back downstream or exhausts them to the point of inability to continue their journey upstream.

FishLadder

Brief historical overview of the weir

Concerns about fluctuating levels of Wizard Lake and downstream flooding in Conjuring Creek began in the early 1980s (according to Leduc County records). In response, the counties of Leduc and Wetaskiwin partnered to build a weir on the eastern side of Wizard Lake where the lake flows into Conjuring Creek.

Leduc County obtained an interim license in 1989 from the Department of Environment (now known as the Alberta Environment), which would allow for the construction of the Weir.

The counties of Leduc and Wetaskiwin entered into a funding agreement with the Department of Environment for the engineering and construction of the Weir in 1989; the agreement was further amended in 1991 outlining the Department of Environment would cover 100 per cent of the costs.

In the fall of 1991, the weir and fish ladder were constructed; the engineering and construction work was performed by external resources (hired by counties of Leduc and Wetaskiwin).

The elevation (784 m above sea level) and location were determined on the advice of the Department of Environment and historical surveyed information. This information and proposed elevation was circulated to landowners along the lake and advertised in the local newspaper; no concerns were expressed regarding the construction of the weir or diversion of water.

Fish and Wildlife Division did provide comments and advice to the Department of Environment with regards to the operation of the fish ladder component of the weir; Department of Environment then provided these recommendations to Leduc County for the operation of the fish ladder.

Operation of the fish ladder and weir

Leduc County has contracted a local individual to operate the fish ladder within the guidelines provided by Alberta Environment. These guidelines include:

  • Daily inspections from April 15- May 15
  • Open the fish ladder when fish are observed downstream of weir
  • Keep the ladder open until no fish are observed.
  • Close the ladder in the evening then inspect it the following morning.  If fish are observed downstream open the ladder again.
  • Continue this procedure until no fish are observed.
  • Periodic inspections (weekly) from May 15 to Dec 1.
  • Ensure that riparian flow is maintained.
Leduc County’s permanent “license” includes  a condition that; “The Licensee shall operate the fish ladder gate to allow to and fro movement of pike across the lake control structure during the annual critical spring spawning period.” Leduc County has also been provided approval to use the small gate to control the 4”x5” (20 square inch) opening for water supply to riparian users and livestock watering.

For more information, contact Rick Thomas, General Manager of Community Services at 780-955-6415 or by email




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