There are two phases to the Cougar Creek mitigation project. The first phase was short-term mitigation which has been completed, work in now underway on long-term mitigation. This page contains information on the short-term mitigation that has been completed, as well as information on long-term mitigation.
Short term mitigation works were completed before the 2014 spring run-off. The mitigation work included widening and deepening the creek bed and installation of articulated concrete mats for erosion protection in the main channel of Cougar Creek, from the Wildland Park Boundary to the Trans-Canada Highway. Additionally, a 6m tall and 40m wide debris net was installed at the apex of the fan to capture up to 15,000m3 of sediment. The debris net is a temporary protection structure until the debris flood retention structure is constructed.
Long-Term Mitigation: Debris Flood Retention Structure
What will it look like?
- 34m high rock-filled embankment dam (not constructed out of concrete).
- Upstream and downstream faces covered by soil and seeded.
- 20m wide rock-cut spillway on the east abutment that includes wildlife egress areas.
View from the air
View from the banks behind Canyon Road
What will it do?
- Existing channel and downstream culverts can accommodate 50-60 m3/s, but a natural event on the creek could easily reach 80 m3/s peak flow with 20% debris (fine sediment to large boulders, including gravel and woody debris).
- The Structure reduces peak flow to 45 m3/s. It further reduces quantity of debris and removes the larger debris.
- The risk to downstream private and commercial properties, as well as infrastructure, is therefore reduced to an acceptable level.
- There is no water retention during regular operation (dry dam) – water flows freely through a low level outlet.
- A high capacity spillway is required to ensure flows can bypass the structure during an extreme flood event.
- The Environmental Impact Assessment (EIA) has been deemed complete by Alberta Environment and Parks (AEP).
- The Natural Resource Conservation Board (NRCB) has issued a positive decision regarding the project. However, due to recent design changes, the NRCB is re-evaluating the project and might amend its decision.
- AEP is drafting the required land disposition to construct, operate and maintain the Structure in the Bow Valley Wildland Park.
- The project team is finalizing the design of the Structure to submit an application for Water Act Approval.
- Construction will begin once approvals and permits are in place.
For more information and history on Cougar Creek visit the Creek Resources Webpage
As of January 2019:
Debris Flood Retention Structure
- The pdf Environmental Impact Assessment Report (130.63 MB) was submitted to Alberta Environment and Parks (AEP) in July 2016.
- The Dam Safety submission was submitted to AEP in August 2016.
- AEP sent the Town Supplemental Information Requests (SIR) in December 2016. The Town has submitted to AEP the pdf SIR 1 Response Package (64.12 MB) in June 2017. The Town has also submitted pdf Post-Submission Clarifications (338 KB) in July 2017.
- AEP sent the Town Supplemental Information Requests (SIR) 2 in October 2017. The Town has submitted to AEP the pdf SIR 2 Response Package (14.38 MB) in December 2017. Moreover, the Town has also submitted an pdf EIA Project Update (7.48 MB) in December 2017 which describes design changes made to the Structure since the submission of the EIA.
- AEP sent the Town Supplemental Information Requests (SIR) 3 in March 2018. The Town submitted to AEP the pdf SIR 3 Response Package (303 KB) in March 2018.
- The pdf EIA (226 KB) has been deemed complete by AEP on March 23, 2018.
- The Town applied to the NRCB and AEP for the construction of the Structure on April 11, 2018 and the NRCB had provided the following pdf Notice of Application (119 KB) .
- The NRCB issued approval for the Cougar Creek debris flood retention structure on November 15, 2018. The following pdf news release (133 KB) and pdf background information (129 KB) has been issued by NRCB. The complete pdf Board decision (2.77 MB) is a 90 page document outlining the decision process and the conditions of approval.
- Request for Proposal was issued in 2018 to find a well-established Canadian firm specialized in dam construction in mountainous terrain in western Canada. They have completed the first phase of work, including high-level cost estimates. To improve constructability and reduce costs and construction time (by 6-12 months), CPL recommended the Town consider alternative approaches to constructing several project elements. The alternative approaches retain the same risk reduction to residents and infrastructure downstream, do not change the structure location, and are designed to the same high standards, such as the Canadian Dam Association Guidelines and Alberta’s Dam and Canal Safety Directive.
- A written project update will be submitted in early 2019 to AEP, the NRCB and Treaty 7 First Nations to provide the information they require to complete any additional review needed. The approval process is still unclear and the NRCB may amend their decision or may issue an addendum to the existing decision once their review is complete.
- Administration is working on the Water Act application package. It will be submitted in early 2019. Time frames for permits remain uncertain.
- Administration is working with AEP to ensure that the required land disposition is in place by the time of construction(a disposition is a land use contract that gives specific rights to a land or resource use).
- Construction start date is uncertain, but the construction duration expected to be 24 months