Changes proposed to steep creek hazard and risk maps
Thursday, Dec 21, 2017 06:00 am
Changes being proposed to Canmore’s steep creek hazard and risk policy includes expanding study areas to include creeks next to land that could be developed in the future.
Maps included in the policy are proposed to be changed to make them clearer about what has and what hasn’t been studied, in relation to mountain creeks, according to manager of engineering Andy Esarte.
Studies of Pigeon Creek and Stewart Creek have not yet been officially included in the policy either, or added to maps that detail the hazards those particular steep creeks pose to the community.
While council heard details about the two creeks and other changes proposed to policy maps at its Dec. 5 meeting, a request from the Bow Valley Builders and Developers Association (BOWDA) and an affected landowner to have more time to consider changes was granted. Council accepted the report as information and expects it to return in future for approval, once the industry has had time to reflect on what the implications of the changes are.
Esarte said the June 2013 floods opened the eyes of everyone in Canmore to the realities of debris flows and floods in steep mountain creeks.
“In response, council approved the study of creeks, short-term mitigation, structural protection and tools to support planning and emergency response,” he said. “As a result, in what could have been an episode that fragmented our community, we showed the opposite. Not only were we resilient, but we got stronger through that test.”
In 2016, alongside an updated Municipal Development Plan, council approved a steep creek hazard and risk policy, the first of its kind for a community in Canada. Esarte said the policy is progressive and provides a framework for future development that does not put the community at excessive risk.
The policy establishes risk thresholds and clearly defined hazard areas through the maps included in it. The maps set out steep creek study areas, hazard zones, and development hold zones. The currently approved policy includes detailed risk and hazard analysis of Cougar Creek, Three Sisters Creek, Stone Creek in Silvertip, Stoneworks Creek along Palliser Trail and Stones Canyon Creek near Peaks of Grassi.
There is a clear impact on development as a result of the maps in the policy, with development hold zones in place for Cougar Creek, for example, until long-term mitigation is completed. Esarte said the objective is to ensure that risk is at an acceptable level for development to occur.
Future study areas are included in the policy maps and Esarte noted changes being proposed to what is considered as future areas of study. Three Sisters Creek, he said, for example, was studied early on and modelling done for where development is located in relation to the hazard and risk.
New development, or changes to developable lands that could and might be considered in the future for the other side of the alluvial fan that is affected by that creek, on the other hand, have not been studied and administration wants the policy to reflect that.
“In areas where things can change, we are clear that only the scenarios studied are shown in policy maps, and all other areas which could in future become hazardous but have not been studied at this time, are defined as future study areas,” Esarte said.
The future study area adjacent to Stones Canyon Creek, Three Sisters and Stewart Creek are all proposed to be changed to reflect that objective.
New development would have to determine hazards as a project progresses through the process, so by the time it is at subdivision, hazards should be fully defined and addressed.
“Certainly it is ideal to leave room for a natural hazard to run its course,” Esarte said. “As you start to develop on both sides of (an alluvial) fan, your options for how you mitigate becomes narrower and narrower.”.