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Hillman Marsh breach

Hillman Marsh Restoration Plan

The Hillman Marsh Conservation Area, located in Leamington, Ontario, is a barrier-protected coastal wetland and is classified as an Environmentally Significant Area, Provincially Significant Wetland, and an Area of Natural and Scientific Interest. As a part of Carolinian Canada, Hillman Marsh helps to preserve hundreds of rare and endangered species that are seldom seen in Ontario, including the American Lotus, Blanding’s Turtle, King Rail, Large Yellow Pond-lily, Least Bittern, Midland Painted Turtle, Northern Map Turtle, Piping Plover, Prothonotary Warbler, Snapping Turtle, Spiny Softshell, and the Swamp Rose-mallow. In 1989, two dykes were constructed creating two controlled wetland cells that allow for water level control carried out by a pumping station. Drawdowns are completed every 10-15 years, removing most of the water from the cell, exposing the mudflats and allowing for seeds to germinate. In the past, this has resulted in a 30-48% increase in vegetation cover. Since breaching, the open marsh is no longer protected from Lake Erie, resulting in impaired water quality and harsh wave conditions. Subsequently, most submerged aquatic vegetation, tree cover, and woody vegetation has been lost or dislodged, making these controlled wetland cells more crucial than ever.

This plan will propose recommended actions to reduce climate change risks and enhance coastal wetland resilience for long-term health, function, and the provision of wetland goods and services. This plan consists of three main goals, and phased objectives to achieve these goals:

    1. Employ a transformational adaptation approach to restore and enhance the Hillman Marsh barrier beach feature to withstand climate change extremes, protect the wetland ecosystem, and safeguard homes and businesses.

    2. Restore the wetland plant community within the approximate 115 hectares of open water behind the barrier feature to enhance wetland structure, function, diversity, and resilience to climate change impacts using historical records and expert opinion.

    3. Make the restored and enhanced Hillman Marsh ecosystem accessible to all of society and future generations to enjoy.

  • 1. Beginning in Spring 2024, utilize available resources and expertise to conduct numerical modelling of natural conditions (waves, sediment transport, and hydrodynamics) and physical modelling of design components (alignment and elevation of the barrier, offshore rock shoals, artificial reefs, and outlet geometry) with a collective aim to minimize wave agitation, ensure infrastructure and vegetation survival, and determine optimal dimensions and materials of critical design components.

     

    2. In Fall 2024, implement upgrades to the south headland at East Beach Road and construct a 40 m test section of the proposed artificial barrier to mitigate ongoing erosion and anchor the future phases of work.

     

    3. By early 2025 and into 2026, and with permits and approvals secured, integrate the results of numerical and physical modelling to complete the final detailed design and cost estimate of project elements and begin construction to stabilize the north headland.

     

    4. By Spring 2026 and into 2027, develop both an adaptive management plan and a comprehensive set of construction ready drawings and specifications, including tender packages that will be utilized to secure quotations for the various phases of construction. Following this, commence construction of the artificial barrier beach and permanent outlet.

     

    5. By Spring 2027 and into 2028, begin construction of hydraulic training structures and extensive wetland restoration, and implement an adaptive management plan involving continuous monitoring, risk identification and mitigation, and stakeholder engagement, allowing for future adjustments in response to changing conditions and unforeseen challenges.

     

    6. Throughout all years of the project, effectively communicate with stakeholders, rightsholders, and the local community to inform, garner support, and seek feedback and approval through quarterly meetings, consultation events, and consistent updates to the project website.

Goals and Objectives 

Climate Change Threats

This plan will propose recommended actions to reduce climate change risks and enhance coastal wetland resilience for long-term health, function, and the provision of wetland goods and services. This plan consists of three main goals, and phased objectives to achieve these goals:

  • Lake levels are projected to increase in variability, resulting in more extreme highs and lows. Water level regimes define wetland processes, soil moisture conditions, vegetation dominance, and shoreline conditions. Water level changes need to be gradual to optimize wetland function and structure, therefore both extreme scenarios will alter species found within a wetland, and result in a decline in biodiversity and ecosystem services.

  • Climate change will also result in an increase in both the frequency and intensity of storm events. These extreme storm events produce intense waves that can cause coastal structures to breach. The barrier beach was the first line of defense against wave action, but without this protection, structures that were not built to withstand Lake Erie are compromising the controlled wetland cells, and surrounding homes and businesses.

  • The increased frequency and intensity of storm events can lead to increased sediment and nutrient runoff, which will result in water quality impairments such as high turbidity, eutrophication, and algal blooms. Excess sediments will lead to the burial of plant communities, a decrease in light penetration and photosynthesis, and a lack of oxygen.

  • Warming air and water temperatures will reduce winter ice cover, which is imperative in protecting shorelines from extreme storm surges as the ice prevents sediment loss from wave action. The absence of ice will also leave shoreline properties vulnerable to flooding. In the past this has resulted in the construction of shoreline protection structures, which in turn disrupt longshore drift, cuts off sediment supply, and disrupts normal processes of wind, wave, and current movement.

Final Recommendation

Based on the opinion of experts on our Core Team and Steering Committee, and the opinion of the majority of the general public, ERCA recommends this project moves forward with Concept A as the preferred approach. The high crested barrier protects the marsh and provides the greatest opportunities for habitat restoration and vegetation re-establishment both on the barrier and behind it. Concept A is more robust and therefore more resilient against wave action, storm events, erosional forces, and future climate change extremes. Through in-depth discussions with various experts, ERCA recognizes that a low crested barrier presents a more dynamic system that will be better suited for wildlife and provides the fundamental services and structure for a healthy wetland. However, concerns remain that Hillman Marsh may not be able to handle this dynamic system, without failing, given its current state. Moving forward, numerical and physical modelling will be conducted by engineers to test the possibility of a structure that has variable crest elevations. If areas of both high and low crested barrier beach can be accommodated without compromising the wetland, then it will provide for a more biologically diverse outcome and will be pursued.

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Caldwell First Nation has been part of the steering committee since its inception, but as the only other landowners in the marsh, staff would prefer to not commit to any preferred option, but instead to continue ongoing consultation with their leadership and community regarding their opinions. Administration has committed to continuing to work and communicate with and seek feedback from Caldwell First Nation if funding for this project is approved and it can move forward.

June 28, 2023: On-site meeting with Steering Committee and Caldwell First Nation.

July 6, 2023: Letter of Advice obtained from Fisheries and Oceans Canada for Phase 1 works (south headland upgrade, E Beach Rd).

July 7, 2023: Turbidity sensor deployed in Hillman Marsh, collecting continuous measurements of temperature and turbidity at 15-minute intervals.

August 2023: Launch of project website and online feedback form.

August 8, 2023: Project brought forward to Leamington Council.

September 2023: Tender documents for Phase 1 works prepared.

October 3, 2023: First public consultation meeting held in Leamington.

October 10, 2023: Second public consultation meeting held in Leamington.

October 27, 2023: Turbidity sensor retrieved for the winter with a total of 111 full days and 2 partial days of data.

November 2023: Water quality data analysis.

December 2023: Environmental risk assessment completed for project construction.

January 2024: Hillman Marsh Restoration Plan report completed.

January 24, 2024: Steering Committee meeting to decide on final recommendations.

February 15, 2024: Restoration Plan report brought forward to ERCA's Board of Directors, where 19 board members, consisting of mayors, deputy mayors, and councillors of the Windsor-Essex region, supported the plan unanimously.

February 16, 2024: Funding application submitted.

September 2024:  Environment and Climate Change Canada awards the Essex Region Conservation Authority with $4.2 million over 3.5 years to implement the engineering needed to initiate construction. Engineering work includes numerical and physical modeling as well as detailed design development.

October 2024: Phase 1 work completed, including updates to the South Headland at the end of East Beach Road, a pilot section of the barrier beach rock core, and wetland vegetation planting.

Project Updates

Project Partners

The Essex Region Conservation Authority (ERCA) is receiving financial support from Environment and Climate Change Canada (ECCC) to coordinate and conduct research for this project. Preliminary construction and improvements to the south headland is made possible by funding from the Ministry of the Environment, Conservation and Parks (MECP). This project will engage various rights holders and stakeholders in the co-development of a restoration and adaptation strategy for the Hillman Marsh Conservation Area. The Steering Committee includes representatives from:

    • Environment and Climate Change Canada

    • Zuzek Inc.

    • SJL Engineering

    • Ministry of the Environment, Conservation and Parks

    • Ministry of Natural Resources and Forestry

    • Fisheries and Oceans Canada

    • Caldwell First Nation

    • Municipality of Leamington

    • Point Pelee National Park

    • University of Windsor

    • University of Waterloo

    • Ducks Unlimited

    • Leamington Shoreline Association

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