The Government of Alberta manages the production of Flood Hazard Area maps, which identify the areas of land that would be impacted by river flooding during a 1:100 design flood. This means a flood that has a one per cent chance of occurring each year. The flood hazard areas are divided into different zones based on the level of intensity of the flood water.

The maps reflect the existing flood mitigation infrastructure in place at the time of the studies. Going forward, revisions to the Flood Hazard Area maps will be considered when flood mitigation, like the Springbank Off-stream Reservoir on the Elbow River and flood barriers, are constructed or upgraded.

Flooding can cause damage to property, hardship to people and loss of life. Cities use Flood Hazard Area maps to guide local decision-making that will help keep people safe and protect their properties from floods.

The updated Flood Hazard Area maps reflect the latest understanding of a 1:100 flood risk across the province, including Calgary. The province has adopted a new approach to flood hazard area mapping. This approach divides the flood hazard area into four categories (two of which are new) that reflect the level of risk: 

• Floodway: An area where flows are deepest, fastest and most destructive. New development is typically discouraged in this zone. 
• High Hazard Flood Fringe (New): An area outside of the floodway where the flow during a 1:100 flood would be deeper (greater than 1 metre) and/or faster (greater than 1 metre/second) than the rest of the flood fringe. 
• Flood Fringe: An area where the flow during a 1:100 flood would be shallower, slower and less destructive than the High Hazard Flood Fringe. This is an existing classification, but the boundaries may have changed.
• Protected Flood Fringe (New): An area where dedicated existing flood mitigation infrastructure (such as City-owned and maintained flood barriers) protects the area to at least the 1:100 flood level. 

The existing Overland Flow Zone designation is being removed, as these areas are being incorporated into the other zones as appropriate. 

Visit www.alberta.ca/final-flood-studies to view the final provincial flood hazard mapping for Calgary.  

The updated flood hazard map for Calgary shows the impact of the Springbank Off-Stream Reservoir (SR1) and Glenmore Reservoir working in tandem to mitigate flooding. Because of the significant and dependable impact of this mitigation on flood flows, the flood hazard map for the Elbow River downstream of the Glenmore Reservoir has been re-drawn. Some minor adjustments have also been made to the Bow River Flood Hazard Area map downstream of the Elbow River confluence.  

Updated inundation maps have also been created for a full suite of flood sizes, ranging from the 1:5 to the 1:1000 flood.  

The area that will be regulated for land use/development post-SR1 is under the jurisdiction of The City of Calgary, and may include additional associated risk factors such as groundwater, erosion risk areas and future flood risk. 

No. Provincial flood studies focus on river flood hazards – when high water escapes the river and inundates the floodplain. However, many riverside communities in Calgary may experience basement flooding when heavy rain or higher river levels cause changes in the groundwater table.  

As part of the Calgary River Valleys Project, we are completing a groundwater study which is:

• Building an understanding of river-flood related groundwater risk
• Mapping groundwater levels during flood events in river valley areas
• Estimating impact and exposure,
• Exploring options for resilience measures,
• Developing a new groundwater risk overlay zone for Calgary.

Groundwater mapping and resilience measures will be presented during the Calgary River Valleys Project Stage 3 public engagement. 

Both The City of Calgary and the Government of Alberta recognize the importance of timely maps reflecting current, actual risk. Structural mitigation under construction or in planning phases still needs to be reflected in new maps, such as the Sunnyside Barrier.  

Once projects are completed, the province has a process for reassessing the impacts on calculated flood levels and flood maps and will consider impacts on the flood map. In some cases, including for the Sunnyside Barrier, draft maps reflecting the future flood barrier have been included in the study reports that accompany the maps, and the map will be updated once the barrier is complete. 

Upstream flood resilience solutions on the Bow River are critically important for Calgary. 

The City of Calgary continues to advocate to the province for an upstream reservoir on the Bow River, recognizing the importance of a project of this nature for both flood resilience and water security in our community. 

In 2024, The Government of Alberta advanced the Relocated Ghost Dam option to Phase 3 for further study. This potential upstream mitigation on the Bow River is an important long-term milestone at least a decade away.  

If new dams or reservoirs dedicated to flood mitigation are built in the future, and if their impact on flood flows is established to be dependable and significant, the province will re-evaluate hydrology assessments and hydraulic modelling and consider flood map revisions once final construction is completed, if appropriate. 

Many of Calgary’s older communities were built on rivers’ floodplains. Over the decades, our understanding of the flood risk in these areas has improved, leading to safer building practices. Since the 2013 flood, changes have been made to Calgary’s Municipal Development Plan and Land Use Bylaw to provide guidance and better regulate development within the Flood Hazard Area. 

Today, some property-level flood-proofing is required through building regulations during renovations and new builds. Measures may include: 

• Building the main floor above the flood level 
• Installing sump pumps and backflow valves 
• Elevating furnaces and electrical panels 

Other voluntary actions can further reduce damage to homes, such as installing water alarms in the basement and finishing the basement with easy-to-clean materials. 

As part of the Calgary River Valleys Project, floodplain policies and regulations are being reviewed and will be incorporated in the Calgary Plan and Land Use/Zoning Bylaw. 

Regulation in the flood zones is the jurisdiction of The City of Calgary. Until The City of Calgary policies and bylaws have been updated, development applications will continue to be assessed according to existing regulations.

The City also considers information from the updated Flood Hazard Area map to provide advisory comments for further resilience. As always, applicants may draw on additional information in support of their applications. 

Insurers produce and use their own flood maps and have indicated they do not typically use government flood maps.

Both the Government of Alberta and The City of Calgary are happy to speak to property owners about how their property is mapped and can provide information for insurers upon request.

Calgarians can contact 311 to inquire about the status of mapping, applicable bylaw regulations, advisory information or development implications on their property. 

Many of Calgary’s older communities were built on rivers’ floodplains. Over the decades, as our understanding of the flood risk in these areas has improved it has led to safer building practices. 

There are several actions that have advanced The City’s land use and flood resilience context, including the 2014 updates to flood hazard area regulations in the Land Use Bylaw (LUB), and updates to Section 4.4 of the Municipal Development Plan (MDP). 

As part of the Calgary River Valleys Project, floodplain policies and regulations are being updated to protect and enhance our river valleys while helping shape more resilient river communities, through updates to the Land Use (Zoning) Bylaw and Calgary Plan. 

Through updates to our flood hazard regulations, The City is seeking to:

• Align planning and development decisions with investments in flood protection. 
• Leverage land use and development rules to increase resilience against remaining flood risks.  
• Create greater clarity for applicants building in flood hazard areas. 
• Ensure Calgary’s buildings are equipped to bounce back from increasingly severe floods as our climate changes.  
• Creating greater protections for life safety and property through clearer regulations on living spaces in basements in our highest flood risk areas.  
• Account for different types of flood risk, including both overland and groundwater flooding. 

We are committed to engaging with Calgarians and all interested parties prior to making any policy and regulatory revisions. 

The City of Calgary is not responsible for the development of flood hazard mapping. 

Flood hazard maps are developed by the province and provide important information about the most current understanding of our community’s flood risk. The draft mapping released in January by the Government of Alberta reflects the latest understanding of a 1:100 (1 per cent chance) flood risk based on updated the 1:100 flood inundation map released in 2020 and introduces a new mapping approach for the regulatory flood zones, including the new High Hazard Flood Fringe classification. Provincially led public engagement on their new mapping approach took place January 12 to February 12, 2024. 

The new provincial approach to mapping includes the new High Hazard Flood Fringe designation. The purpose of this new zone is to identify areas outside of the floodway where the flow during a 1:100 flood would be deeper (greater than 1 metre) and/or faster (greater than 1 metre/second) than the rest of the flood fringe. 

When the High Hazard Flood Fringe is both fast and deep, it is the second highest flood risk category after Floodway.  

When a High Hazard Flood Fringe Area is only deep (not fast) and, particularly, when it is surrounded by the Flood Fringe Hazard Area, the overall flood risk is lower. The City of Calgary is choosing to look carefully at this distinction within the high hazard flood fringe, to ensure that updated regulations are in line with the flood risk.  

Historically, these areas would have been mapped as floodways, but because this designation is the most restrictive and has significant implications on developability, in established communities, the province has designated these areas as High Hazard Flood Fringe instead of Floodway. This allows municipalities more flexibility in how these areas are regulated, to continue to function as thriving communities. 

The feasibility study for the Bowness flood barrier was completed in April 2021. The results from the study showed a barrier would be effective at helping reduce damage that may be caused by overland flooding.

The project would need to be built on private land, and we worked closely with the community throughout the studies. Through the engagement process, many community members wanted more details on the Government of Alberta’s plans for an upstream reservoir before progressing further with the barrier project. As a result, The City is not moving forward with further work related to a barrier at this time and has no project team or funding assigned. 

Without any community-level structural infrastructure (e.g. flood barrier) in place in Bowness, we must rely more heavily on both a future upstream reservoir and property-level measures where flood-proofing and changes to permissible development and land use must play a more critical role in achieving greater flood resiliency. 

There is currently no assistance available to homeowners located within the flood hazard area who wish to relocate. The properties purchased by the province following the 2013 floods were floodway-specific. The City did not purchase any properties at that time. 

The City's 2017 Flood Mitigation Measures Assessment saw Council approve a primarily Protect in Place strategy. The Triple Bottom Line Assessment conducted as part of this work demonstrated that it would be more advantageous to protect communities than conduct significant buyouts and major land use redesignation. 

Additionally, we have heard clearly from engagement that our river valley communities have unique cultural, historical and economic significance, so intensive assessment of further buyout has not been a favored resilience tool. 

Climate change is shifting precipitation patterns, increasing rainfall intensity and causing an earlier melting of the mountain snowpack. As a result, river flood hazards are increasing for the Bow and Elbow River watersheds. Updating our land use planning policy and regulations is a crucial action in Calgary’s Flood Resilience Plan and our Calgary Climate Strategy.

As part of the Calgary River Valleys Project public engagement on floodplain policies and regulations, we are exploring how climate change risk projections will be incorporated into today’s floodplain planning and development decisions and regulations.

The City of Calgary is responsible for protecting public safety and ensuring that our affordable housing options are not vulnerable to hazards such as flooding.

Generally, floodplain planning aims to reduce the number of people living in flood-impacted areas, especially areas with a higher risk of flooding. Basements (including living areas or secondary suites) are vulnerable to flooding because underground spaces can quickly fill with water, risking life or personal safety and property damage. During river flood events, basements can be flooded by overland floodwater or high groundwater that enters the basement through cracks and drains. 

We are considering new rules to minimize flood impacts to below-ground living spaces. Importantly, these rules will be targeted to areas that are at highest risk of flooding within our flood risk communities and will only apply to new buildings and development. This leaves many other safer and more available areas for increasing housing choice, including within lower risk portions of flood risk communities. 

As our city continues to grow and the information available about flood risk evolves, it is important that we continue to revisit our land use policies and building regulations in flood hazard areas to guide how we plan and develop in river communities to make them more resilient.

The Calgary River Valleys Project has been a key contributor to the City Building Program by:

• Incorporating updated river valley, creek and flood hazard policy in the Calgary Plan, available at engage.calgary.ca/citybuilding. This plan is intended to go committee in Q2 2026. 
• Updating flood hazard regulations for both the Land Use Bylaw and future Zoning Bylaw.