Coats Marsh Weir Decommissioning

The Regional District of Nanaimo (RDN) is planning on removing the concrete weir in Coats Marsh Regional Park on Gabriola Island.

The existing concrete weir in Coats Marsh does not meet provincial safety standards and requires removal or replacement. The RDN is planning to remove the weir from Coats Marsh while keeping the upstream beaver dam in place to preserve the majority of the wetland ecosystem in its present state.

Coats Marsh Regional Park includes approximately 10ha of wetland which drains into Coats Marsh Creek. The wetland is retained by a concrete weir and by a beaver dam, which is approximately 55m upstream of the weir. The locations of the weir and beaver dam have effectively created a "lower" pool located between the weir and beaver dam, and an "upper" pool whose water level is determined by the beaver dam elevation. The upper pool is considerably larger than the lower pool and forms most of the marsh.

More information on the history of the project and how this decision was arrived at can be in the FAQ section of this page.

The final Coats Marsh Dam Decommissioning Plan is complete and is available for review in the Documents section of this page.


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The Regional District of Nanaimo (RDN) is planning on removing the concrete weir in Coats Marsh Regional Park on Gabriola Island.

The existing concrete weir in Coats Marsh does not meet provincial safety standards and requires removal or replacement. The RDN is planning to remove the weir from Coats Marsh while keeping the upstream beaver dam in place to preserve the majority of the wetland ecosystem in its present state.

Coats Marsh Regional Park includes approximately 10ha of wetland which drains into Coats Marsh Creek. The wetland is retained by a concrete weir and by a beaver dam, which is approximately 55m upstream of the weir. The locations of the weir and beaver dam have effectively created a "lower" pool located between the weir and beaver dam, and an "upper" pool whose water level is determined by the beaver dam elevation. The upper pool is considerably larger than the lower pool and forms most of the marsh.

More information on the history of the project and how this decision was arrived at can be in the FAQ section of this page.

The final Coats Marsh Dam Decommissioning Plan is complete and is available for review in the Documents section of this page.


Want to get involved and stay updated about this project?

  • Sign up for project updates by subscribing and leaving your email address and we will email updates about the project as it progresses
  • Check out the Project Updates tab below for project updates
  • Submit a question through the Q & A tab below

  • Dam Decommissioning

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    The decommissioning of the existing weir is scheduled to begin on Friday, August 15, 2025, and will take approximately 2 months to complete. For public safety, the area around the weir, as well portions of Stump Farm Trail and Marsh Trail will be closed while the work is ongoing. Please be cautious and remain alert to construction activities while using the park and nearby trails.

    The work will include:

    • Demolition of the existing weir structure;
    • Infill grading around the existing berm;
    • Overflow channel excavation at the marsh outlet;
    • New reinforced concrete grade control structure at the marsh outlet.

  • Final Dam Decommissioning Plan

    The final Coats Marsh Dam Decommissioning Plan is complete and has been submitted and approved by Province. The final dam decommissioning design includes several key elements:

    • Complete removal of the existing concrete weir structure;
    • Placement of fill material to the west of the existing berm;
    • Removal of accumulated sediment near the weir;
    • Construction of a 1.2 m high concrete grade control structure at the marsh outlet. The structure does not enable storage or diversion of water within the marsh and is not considered a dam;
    • Widening a portion of the outlet channel to mitigate beaver activity and improve flood conveyance capacity in the event of an upstream beaver dam failure.

    Construction will occur in the late summer/early fall, with instream works being carried out during the least risk timing window of August 15 to September 15.

    The final plan can be found in the Documents tab of this page.

  • Environmental Impacts and Mitigation Measures for Weir Pool Area

    The consulting team has completed the Weir Pool Environmental Impacts and Mitigation Measures report for the Coats Marsh weir decommissioning project. The document includes detailed recommendations for the following:

    • Replanting the weir pool area with native species following decommissioning.
    • Removal and mitigation of invasive species, particularly reed canary grass.
    • Minimizing the construction impacts on amphibians through an amphibian salvage program during construction and the potential creation of new amphibian habitats in the weir pool area.

    These mitigation measures will be incorporated into the final decommissioning plan for the Coats Marsh weir.

    The document is posted in the Documents tab of this page.

  • Beaver Dam Risk Assessment

    The consulting team has completed the Beaver Dam Risk Assessment for the Coats Marsh weir decommissioning project. The document includes downstream flood mapping and commentary on the potential risks of various beaver dam breach and precipitation event scenarios. The document is posted in the Documents tab of this page.

  • Public Information Session

    A public information session will be held from 11 a.m. - 3 p.m. on Saturday, January 20, 2024, at the Gabriola Art & Heritage Centre, located at 476 South Rd, Gabriola.

    This is an opportunity to learn more about the project and discuss any questions you may have with RDN parks staff and the project consulting team.

    The meeting will be drop-in style with no formal presentation.

Page last updated: 06 Aug 2025, 11:34 AM