In 2013, much of southern Alberta experienced high flood waters, including the mountain town of Canmore. Over 220 millimetres (8.7 in) of rain fell in just 36 hours, which was nearly half of the town’s annual average rainfall.
Cougar Creek, which drains runoff from a number of mountains north of town, overflowed due to debris such as trees and boulders. Cougar is a popular cragging canyon with over 100 quality 5.10 and 5.11 sport routes. Development started back in the 1990s. Planet X is the farthest crag in the canyon and has many now-classic 5.13 an 5.14 lines.
A two-year dam construction project started this spring and is expected to close access to the creek for the duration starting this summer. Watch a video of the flood below.
Cougar Creek Flood 2013
The $48.8-million structure will be located about two kilometres northeast of the Trans-Canada Highway. The dam is being built to protect the town and critical infrastructure from future floods. Anyone who’s visited Cougar has seen the large home on the eastern edge of the creek, it’s the last residence on Canyon Road. Due to the construction project, the owner has listed the home for sale at $8.7 million, see here for more info.
“This project is necessary to prevent the type of damage we saw in 2013 and to provide protection from the much larger floods we now understand can happen along Cougar Creek,” said Canmore Mayor John Borrowman.
“This area is prone to dangerous debris floods, as well as landslide dam outbreak floods, that can cause tens of millions of dollars in damage, disrupt the Trans-Canada Highway and CP rail line, and put many lives at risk. We’re looking forward to having this protection in place. A large proportion of our community will rely on this structure for protection for their homes and business. And, it will bring certainty that the Trans-Canada Highway and CP rail lines can remain open at this location the next time we see a flood like the one we experienced in 2013.”
The province is providing $30.3 million for the project, while the federal government is providing $14.5 million. The town is kicking in $4 million and is also responsible for operating costs and maintenance. The project will be tendered in the coming weeks. Construction is expected to be finished in spring 2022.
The structure itself will be an earthen dam with a rock-cut spillway and concrete and steel pipe low-level outlet. Borrowman said contractors will face several obstacles related to digging as well as re-routing the creek while work is being done.
“Deep foundation work will be a challenge,” he said. “We’re working in a constrained area with flowing water and will dig up to 10 metres into the channel to create a foundation on bedrock. This phase of the work requires dewatering and re-routing the creek flow past the construction area. To complete this work we will construct a bypass channel.”
As part of the approval, the town will be required to allow First Nations to hold a pre-construction ceremony, and to harvest traditional plants in the area. Water quality and quantity monitoring also must be done during construction.
“This is the first steep creek to have been studied for debris flood, debris flow, and landslide dam outbreak flood hazards to this extent in Alberta,” said Borrowman. “The work required an in-depth study of the catchment and alluvial fan where the community has developed.”