Mamquam Blind Channel (MBC) Long-Term Maintenance and Dredging Strategy

Mamquam Blind Channel

Photo Credit: Canadian Coastal Sailing

The District of Squamish has initiated an ecosystem-based channel maintenance, dredging and funding strategy to support ongoing navigational safety, accessibility, habitat and coastal protection and restoration, and community, cultural and regional economic vitality of the marine/gateway area. This page summarizes the project’s purpose and intended outcomes, key stages and major tasks, and the planned engagement program through 2022-23.

Background

The MBC is a critical marine gateway for the Squamish community: for the Sta’7mes community and village site, for recreational boating and watersports key to the tourism sector, as well as industrial, commercial and marine transportation services essential to the local and regional economy. Ongoing sedimentation and changes in the channel, particularly near the confluence of the Stawamus River delta, are impacting safe navigation during low tides. While historic dredging in the MBC has occurred over time to facilitate use of the waterway, in the past 30 years there has been limited dredging. The last significant channel maintenance was undertaken by federal agencies in 1986, with some further dredging in 1996-97. In 2013, it was estimated that to provide safe navigation of the channel, approximately 80,000 to 100,000 m3 of material needed to be removed.

Previous studies identified that the Stawamus River produces approximately 2,500 m3 of sediment annually. A minor dredge project was completed in 2013 removing approximately 5,000 m3 of material from the channel as a short-term stop-gap. The need for a long-term program and funding strategy has long-been recognized.

Establishing a long-term channel maintenance strategy for the MBC was highlighted in the 2016 Official Community Plan, and identified as a priority action in the 2018 Squamish Marine Action Strategy:

OCP Policy 20.24 e. Develop a dredging strategy for the Mamquam Blind Channel as needed in order to address navigability for transportation, recreation and commerce, while minimizing impacts to marine habitats and biodiversity


MBC Study Area

The MBC is a designated navigable waterway regulated under the Canadian Navigable Waters Protection Act (CNWA). The study area for the dredging strategy was established with the objective of prioritizing and focusing on navigational safety within the most actively used reaches of the channel (the CN Rail and Highway 99 bridge crossings effectively limit boat traffic). The MBC beyond the rail bridge is a non-scheduled waterway under the CNWA.

Project area map

Project Stages and Major Tasks 2021-2023

Development of the MBC maintenance, dredging and funding strategy is following a four-stage process, initiated in late 2021:

1: Initial Data + Knowledge Gathering : Baseline Technical Documentation (Dec 2021-April 2022)

Key Tasks:

Engage engineering and environmental consulting services, Existing information and knowledge review, Navigation channel survey, Initial estimate of sediment volume and dredge locations, Assessment of dredging impacts on surrounding properties, lands and environment, Preliminary environmental impact assessment.

Engagement activities:

  • Develop engagement planning, working group terms of reference and recruitment
  • Online project information page creation
  • Intergovernmental early outreach and referrals; meetings
2: MBC Strategy Development (March-December 2022) * We are here *

Key Tasks:

Continue information and knowledge review; Review Navigational Channel Design, Dredge material re-use potential and estimate of future sedimentation, and regulatory requirements review. Confirm Cost Estimates, conduct community impact analysis, and discuss long-term funding options. Intergovernmental and stakeholder engagement. Draft report with options and long-term channel maintenance funding strategies.

Engagement activities:

  • Intergovernmental meetings and working group meetings on technical review, potential restoration and dredge options, costs and priorities
3: MBC Strategy Review + Refinement (Winter 2022/23)

Key Tasks:

Further intergovernmental and stakeholder engagement on draft strategy.

  • Engagement: ongoing working group consultation and public open house.
  • Council workshop to review and confirm strategy directions
4: MBC Strategy Completion + Endorsement (Spring 2023)

Key Tasks:

Summarize final engagement, key edits, and recommendations for final endorsement and implementation.


Engagement Program

In late April 2022, District of Squamish Council endorsed the scope and engagement plan, including governments, regulators, key stakeholders and the public with interests and who may be impacted by the project. The engagement program also specifies recruitment of a working group to provide local knowledge, perspectives and guidance to the project.

The project involves early and ongoing engagement and involvement with Squamish Nation, as well as soliciting guidance from governmental agencies in the marine realm, and inputs from key stakeholders and the broader community. The District’s cross-departmental project team (Engineering/Environment, Planning, and Economic Development) will be jointly leading engagement activities with project technical and administrative support by Westmar Advisors Ltd. In Fall 2022, the project team will solicit intergovernmental input and direction, then host a series of technical sessions with a community working group to review the technical information, and provide input on potential dredge areas, impacts, options and funding aspects. A community Open House will be planned once initial options are developed for broader community feedback.

Community Working Group

The project has recruited and is engaging a voluntary cross-sector community working group to advise on the technical channel maintenance and dredge strategy development for the project period. The mandate of the MBC Working Group is to engage with the District and technical consultants to review information, identify the relevant values, needs and community priorities for marine access and coastal protection and stewardship, and provide input, evaluate options and make recommendations on the development of the long-term ecosystem-based dredge management and funding strategy for the Mamquam Blind Channel.

The voluntary working group is advisory and time-limited (to be disbanded upon completing identified tasks). The working group will meet 3-4 times over the course of Fall/Winter 2022 and then summarize its inputs and findings, and make recommendations to staff and Council. A comprehensive engagement summary will be produced and shared as part of the engagement process.

Working group meetings are open to the public as observers; as Chair for the meetings, the District of Squamish will provide opportunity for members of the public to ask questions and offer points of information at the end of meetings.

Project Team Contacts

David Roulston
Manager of Municipal Infrastructure
droulston@squamish.ca, 604.815.4952

Sarah McJannet
Senior Planner
smcjannet@squamish.ca, 604.815.5002

Kate Mulligan
Economic Development Officer
kmulligan@squamish.ca, 604.389.8017

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Comments

  • Marc d'Entremont Oct 11, 2022, 11:47 PM (58 days ago)

    Would increasing the flow of water in the Blind channel decrease the need for dredging?

    • Communications Oct 12, 2022, 11:45 AM (57 days ago)

      Thank you for your question, Marc.

      An increased flow of water has limited potential to reduce the need for dredging in the Mamquam Blind Channel. While water flowing through a channel has potential to flush out deposited sediment, it requires relatively high velocity which is not considered possible to achieve in the Mamquam Blind Channel. This is due to the limited freshwater inputs as well as the width of the channel, and extent of sediment inputs mid-channel at the Stawamus River outlet. To generate sufficient velocity in the Mamquam Blind Channel to scour sediment would require major work such as diverting a large portion of flow from the Mamquam River through the developed floodplain into the upper Blind Channel which is not considered feasible. In addition, the last major dredging activities in the channel took place in the 1980’s and there has been considerable build up of sediment over the past nearly 40 years that would require a large dredging effort to reinstate the channel to its previously dredged depth.

      The District has worked in partnership with Squamish River Watershed Society and Department of Fisheries and Oceans on the Mamquam Reunion Project which diverts a small portion of flows from the Mamquam River through a series of natural and constructed channels in the floodplain to the Upper Mamquam Blind Channel to improve aquatic habitat. However, these enhanced water flows are not adequate to achieve scouring velocity in the channel. For more information on the Mamquam Reunion Project: Mamquam River Reunion - Squamish River Watershed Society (SRWS) (squamishwatershed.com)

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