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10 Street Gravel bar

Over the past several decades, a gravel bar has been forming in the Bow River under the bridge that connects 10 Street N.W. to downtown, known as Louise Bridge or Hillhurst Bridge.

The bridge connects the communities of Hillhurst, Kensington and Sunnyside to the west end of downtown Calgary.

Project Update – November 2023

The project team is currently working on the preliminary design for the 10 Street Gravel Bar project.

Through partnership with the National Research Council of Canada (NRC), we are assessing the project reach using a physical scale model of the proposed gravel bar realignment. The model will evaluate the performance of the preliminary design under a range of river flow conditions. After each run-through we will adjust our design to better address flooding and erosion risks and improve design longevity. We will progress into detailed design after this stage is complete.

Findings and lessons from this project will be integrated into new guidelines for nature-based solutions which are currently being developed by the NRC. This project is funded in part by the NRC’s Climate Resilient Built Environment Initiative, in support of delivering the Government of Canada’s Adaptation Action Plan, and towards achieving commitments under the National Adaptation Strategy.

Below are photos of the scale model being constructed.

Scale Model gallery


Project overview


Gravel bars form naturally in rivers from sediment movement. They become a concern when they form in and around bridges and constrict flow of the river.

  • The 2013 flood resulted in a dramatic increase in size of the gravel bar.
  • Since 2013, the gravel bar has become covered with plants including trees which are expected to continue growing in size, increasing flood risk to the area.

The continued growth of the bar and its plants increases the flood risk to the surrounding area, by blocking water flow through the bridge and reducing its capacity.

  • This increases water levels upstream that can overflow into the adjacent neighborhoods.
  • It also causes erosion along the opposite bank and bed of the river which can put infrastructure, including bridges, outfalls and pathways at risk.

The aerial images below show the gravel bar’s increase in size after the 2013 flood. The green dashed line indicates the riverbanks before the flood, and the purple dashed line indicates the banks after the flood.:

Aerial image of project area in 2012 (before flood)

Aerial image of project area in 2014 (after flood)

Gravel bar realignment


The approach to lowering flood risk is to realign the gravel bar. This means that the gravel and soil would be removed and redistributed within the area of the river using a nature based approach.

  • Realignment of the gravel bar would provide long-term flood mitigation benefits and be the most environmentally beneficial and stable solution.
  • We can improve fish and riparian habitat in the area and naturalize the south bank by redistributing the removed materials.

Recreational wave


There is a natural wave adjacent to the gravel bar which has been used for recreation such as river surfing.

  • This wave has been decreasing as natural sediment movement continues to occur and the gravel bar increases in size.
  • The area is hazardous for river rafters and floaters since they need to navigate around the gravel bar and can get stuck on the boulders where the river turns after the bridge.
  • Realigning the gravel bar would result in safer navigation for river users.

The project team is exploring incorporating a permanent recreational wave as part of this project. We are working with the Alberta River Surfing Association and the Alberta Whitewater Association who provide expertise and represent river recreation user groups. 

Adjacent Projects


The 10 Street Gravel Bar project is occurring in parallel with several other City projects and initiatives that will work in coordination with one another to deliver their mandates. These include:

RiverWalk West
Calgary’s Downtown Strategy
Harvie Passage
Sunnyside Flood Barrier

Next steps


We are currently in the preliminary design phase, with detailed design happening in Winter to Spring 2024. The construction schedule and impacts will be determined as we move further along in the design process. Please check back on this page for updates throughout the project.

Timeline

  • Preliminary design – Spring to Fall 2023
  • Detailed design – Winter to Spring 2024
  • Construction – Schedule to be determined

Budget

The estimated cost for this project is $10 million.

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For more information or questions, please email the project team at 10stgravelbar@calgary.ca


This information has no legal status and cannot be used as an official interpretation of the various bylaws, codes and regulations currently in effect. The City of Calgary accepts no responsibility to persons relying solely on this information. Web pages are updated periodically. ​

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