Policies and measures for reducing flood risk in the City of Calgary

Building flood resiliency is a top priority for the City of Calgary, following the extreme flooding event of 2013 that resulted in $6 billion in damages, including over $400 million to infrastructure. The City’s approach to reducing flood risk uses multiple lines of defence at the watershed, community and property levels. The City’s 2017 Flood Mitigation Measures Assessment Report focuses on increased protection in critical areas, such as the downtown core and neighbourhoods with high flood-risk. The plan is supported by a combination of barriers at existing reservoirs and protocols related to flood-control, and also depends on upstream reservoirs to provide a high level of flood protection.

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Understanding and Assessing Impacts

In order to better understand the impacts of flooding in the Calgary area the IBI Group along with Golder Associates were tasked with creating a flood damage model for the City through the Flood Mitigation Options Assessment Summary. This model visually represented land which would be affected by floods ranging in size from those with a likelihood of occurring every 100 years (1:100) up to those that may occur sometime within the millennium (1:1000). While a wide range of flood sizes were considered, intentions were to address those up to a 1:200 occurrence probability. This model enabled a scenario analysis which considered flood mitigation options against various flood events. This analysis incorporated a robust cost-benefit analysis which was conducted by overlaying various hard engineering interventions onto models of a 1:200 flood scenario in the City of Calgary. Ultimately the cost-benefit analysis showed that neither hard engineering nor buyouts of land in high-risk areas alone could completely mitigate the costs of future damages. Buyouts were also seen as cost-prohibitive, further nullifying this option. The above-mentioned detailed analysis well exceeds current standards and aided in informing future flood mitigation planning and analysis.

Identifying Actions

Through the Flood Mitigation Options Assessment Summary, a combination of actions was ultimately identified using a sustainability assessment approach. This assessment, spearheaded by the City of Calgary, examined various scenarios which then integrated flood damage modelling information in order to better understand the damage reduction and cost/benefit implications of each scenario. The assessment also explored operational improvements and land use policy schemes. The sustainability assessment allowed for factors such as social well-being, economic well-being, environmental protection, and ease of implementation all to be considered. While the weightings of each factor’s sub-components differed, each of the four main sustainability assessment factors were considered of equal importance. The factors and their components were guided by existing city policy and developed partially through community engagement as well as with public and private sector expertise. The results of the assessment indicated that the single most preferred hard engineering option was that of upstream mitigation through reservoir introduction. This option was favoured thanks to the equitable protection it would provide and its unobtrusive (to city residents) nature. Overall, the summary recommends a scenario (scenario #8) which introduces reservoirs upstream of the Bow and Elbow Rivers, a number of community barriers around the downtown core, as well as less substantial barriers strategically placed throughout the city. While timelines for the implementation of these actions were not made explicit, as of 2021the Springbank Reservoir on the Elbow River awaits approval while the Bow River Reservoir is currently being studied and remains in the conceptual stage. This is due to the fact that these projects are considerably large and fall under Provincial jurisdiction. Conversely, many of the aforementioned community-level barrier projects are at different stages of implementation.


Since the significant flooding of Southern Alberta in 2013 the City of Calgary along with the Province of Alberta have implemented a number of strategies to reduce damage from future floods. Some of these strategies include improvements to forecasting and emergency response, the introduction of community-level flood barriers, gate upgrades at Calgary’s Glenmore Dam, and a Provincial agreement with TransAlta (hydroelectricity provider). Many of the above-mentioned actions occurred relatively rapidly after the flooding event thanks to their low costs and ease of implementation. Exceptions to this characterization are built-infrastructure such as the Glenmore Dam upgrades (completed 2020) and community-level flood barriers (ongoing) which demand more time and funding to materialize. The Government of Alberta has been able to assist in Calgary’s adaptation efforts by extending an agreement with TransAlta to utilize their power generation infrastructure for flood prevention. Further, the Province contributed significant funds to the Glenmore Dam upgrades as well as to the creation of flood barriers. Other major aspects of Calgary’s plan constitute Provincial initiatives whose progress still rest firmly with Provincial authorities. Namely, two major reservoir projects on the Bow and Elbow Rivers which constitute a large portion of Calgary’s Flood Resilience Plan but which lie outside of its jurisdiction. The Elbow River reservoir is currently awaiting Provincial approval, while the Bow River reservoir remains in the feasibility stage. This is likely due in part to the high capital cost associated with the projects which top upwards of $1.4 Billion Canadian dollars

Outcomes and Monitoring Progress

To date, the City of Calgary has implemented hard engineering solutions such as improvements to the gate of the Glenmore Dam in the form of the 2.5 metre high steel gates as well as the introduction of flood barriers at various locations throughout the city. These interventions have been said to have reduced the potential average annual damages of future flood events by about 50% to date. The benefits of other steps that the city has taken such as improving forecasting and emergency response systems are less easily quantified. While initial reports by the Expert Management Panel on River Flood Mitigation suggested that appropriate flood level protection be periodically reassessed, the city currently remains in a multi-year implementation phase which includes continuous refinement of their understandings of flood risks, as well as the role of groundwater. Throughout the planning phase the importance of two factors in particular were made explicit by stakeholder groups. Firstly, there was a clear distaste for large, obtrusive and partially effective (groundwater flooding potential remains) flood barriers. Second, many stakeholders expressed their desire for infrastructure interventions which effectively reduced flood risk for their private property. These two pieces of information contributed to the focus on upstream reservoirs in the City’s Flood Resilience Plan. These reservoirs would likely also have benefits for communities situated downstream which may also experience flooding. In fact, the Springbank reservoir (Elbow River) will address 80% of the flooding on this river, a level of protection unattainable by barriers alone. Further, paired with ongoing TransAlta agreements, downtown barriers will protect against 1:200-year flood events.

Next Steps

There are a multitude of next steps associated with future flood prevention in the City of Calgary. Firstly, the aforementioned approval for the Elbow River reservoir must be made by the Province of Alberta as well as further advancement of the Bow River reservoir concept. While a particular location and design for the Elbow River reservoir seems to be favoured – known as Springbank Reservoir (SR1) – public hearings on the topic are set to begin in the spring of 2021, prior to Federal approval which is expected in the summer of the same year. Decisions to further study three competing designs for the Bow River reservoir must still be made. Next, the Province of Alberta are in the midst of ensuring that current agreements with the regional hydroelectricity provider (TransAlta) which allows for use of their infrastructure for flood prevention, is extended beyond 2021. Further, the city intends to consider changes to land use and building codes near the river which may restrict or prohibit uses in particular areas. Preliminary studies which address land use changes suggest that a cost/benefit analysis would be a useful tool to aid in guiding how this option may move forward. Additionally, the city is developing an education program for homeowners in order to better flood-proof their properties. Calgary has also noted that it intends to continue improving flood prevention through areas such as “forecasting, emergency response, citizen education and communication, and preparedness for citizens, businesses and city departments”.