Last updated: October 2024
The South Hennepin Marsh habitat restoration project, located below the Grosse Ile Toll Bridge causeway, within the Detroit River's Trenton Channel near Grosse Ile, Michigan, aims to restore and protect one of the region's most critical wetland habitats. This emergent marsh, historically vital for fish and wildlife, has suffered significant degradation due to river currents, boat traffic, and winter ice flows. The project, identified as a priority in the 2002 Habitat Protection and Remediation report for the Detroit River, encompasses the restoration of over 1,000 linear feet of protective shoals and 20 acres of productive wetlands, home to various native plant species such as rushes and submergent macrophytes. The primary goal of the project is to stabilize and enhance the marsh's habitat, improving conditions for fish, waterfowl, reptiles, amphibians, and other wildlife. Restoration activities include the placement of approximately 10,000 cubic yards of rock and soil to rebuild eroded shoals, installation of erosion matting, and re-establishment of native vegetation. Additional habitat features, including habitat logs, mudpuppy structures, and stone spawning beds, will provide crucial breeding and feeding areas for species such as walleye, northern pike, and lake whitefish. The project also incorporates soft engineering solutions, such as fallen branched trees and strategically placed stones, to support pollinators, birds, and reptiles. Feasibility studies and design plans were completed by Environmental Consulting and Technology, with funding from NOAA, and construction was carried out by E.C. Korneffel Company beginning in 2021. The project reached completion in November 2022, successfully restoring the shoals and protecting the marsh from further degradation. These efforts have significantly enhanced habitat availability, ensuring the sustainability of the South Hennepin Marsh as a critical ecological site within the Detroit River system. (Ref.1-4)
Hennepin Marsh
https://www.detroitriver.org/glri-projects/hennepin-marsh
Overview
Nature-based solution
- Blue infrastructure
- In-land wetlands, peatlands, swamps, and moors
Key challenges
- Climate action for adaptation, resilience and mitigation (SDG 13)
- Climate change adaptation
- Environmental quality
- Soil quality improvement
- Green space, habitats and biodiversity (SDG 15)
- Green space creation and/or management
- Habitat and biodiversity restoration
- Water management (SDG 6)
- Flood protection
- Stormwater and rainfall management and storage
Principal problems in Functional Urban Area (FUA)
- Environmental Degradation
- Biodiversity loss
- Other
Key priorities
Climate action (adaptation and/or mitigation), Biodiversity (conservation and/or restoration)
Focus
Management and improved protection of rivers and other blue areas, Restoration, protecion and sustainable manage floodplains, Restoration of riparian vegetation, Ecological restoration of ecosystems, Soil remediation and revegetation, Restoration of wetlands (other types than peatlands and mangroves, e.g. seagrass), Protection of natural ecosystems, Protecton and enhancement of wetlands (other types than peatlands and mangroves, e.g. seagrass), Habitat restoration
Project objectives
To restore over 20 acres of productive wetlands, safeguarding critical habitat for fish, waterfowl, reptiles, amphibians, and other wildlife species.
To prevent erosion and stabilize the marsh by rebuilding over 1,000 linear feet of protective shoals and implementing erosion control measures, reducing degradation from river currents, boat traffic, and ice flows.
To enhance fish and wildlife habitat by improving conditions for native fish species such as walleye, northern pike, and lake whitefish, through additional spawning and nursery areas created with habitat structures and native vegetation.
To mitigate the impact of climate change and flooding by restoring wetlands and using soft engineering methods, enhancing the marsh’s resilience to rising water levels and increased storm events.
(Ref.1-5)
Implementation activities
The South Hennepin Marsh habitat restoration project was implemented by E.C. Korneffel Company in collaboration with FDR and Environmental Consulting and Technology. A major part of the project involved the rebuilding of over 1,000 linear feet of protective shoals, using approximately 5,200 tons of MDOT Plain Rip Rap, 730 tons of MDOT Special/Armor Rip Rap, and 1,000 tons of 1x3 limestone, donated by Stoneco. This heavy stone material was strategically placed to stabilize eroded areas and ensure long-term protection from boat traffic, wave action, and ice flows.
To further support the stability of these shoals and safeguard them against future erosion, erosion matting and native plant materials were added, which also contribute to the restoration of natural habitats for fish and wildlife. Habitat enhancement efforts included the installation of habitat logs, mudpuppy structures, and the reestablishment of native vegetation, all of which support a diverse array of species, including fish, amphibians, pollinators, birds, and reptiles. The project also included thorough pre-construction and post-construction monitoring efforts, with herpetofauna, bird, and fish surveys, as well as sediment analysis and flow measurements, all conducted to assess the environmental impact and success of the restoration efforts. (Ref. 1-6)
Climate-focused activities
Climate change adaptation:
- Restore mangroves, marshes, reefs and wetlands to dissipate the effects of storms and floodwaters
Biodiversity conservation or restoration-focused activities
Biodiversity restoration:
- Rehabilitate and restore damaged or destroyed ecosystems
- Restore species (native, endangered, or unspecified)
- Restore native species
- Restore valued species
- Restore endangered species
Main beneficiaries
- Researchers/University
- Citizens or community groups
Governance
Management set-up
- Co-governance with government and non-government actors
Type of initiating organisation
- Non-government organisation/civil society
- Private sector/corporate actor/company
Participatory approaches/ community involvement
- Co-planning (e.g. stakeholder workshops, focus groups, participatory mapping)
- Taskforce groups
- Joint implementation (e.g. tree planting)
Details on the roles of the organisations involved in the project
The South Hennepin Marsh restoration project was made possible through a coalition of specialized organizations and agencies, each contributing expertise, resources, and funding. E.C. Korneffel Company, as the lead construction contractor, managed the physical restoration work, including the rebuilding of shoal islands and the installation of habitat structures. Friends of the Detroit River served as the project manager. Environmental Consulting and Technology, supported by Herpetological Resource and Management, LLC, conductedfeasibility studies, engineering designs, and environmental assessments to guide the restoration process. Stoneco donated large quantities of limestone and rip rap, which were used for stabilizing the eroded shoal islands. Financial support was provided by the National Oceanic and Atmospheric Administration. Additionally, the U.S. Environmental Protection Agency, through its Detroit River Area of Concern program, contributed to the ecological recovery. (Ref.1-6)
Project implemented in response to ...
... an EU policy or strategy?
Yes
(Action Plan 2015-2025. Michigan Department of Natural Resources; Natural Resources and Environmental Protection Act, Part 365, Endangered Species Protection (Ref. 1))
... a national policy or strategy?
Unknown
... a local policy or strategy?
Unknown
Type of enablers
NGOs/Community groups driving the implementation
Financing
Total cost
More than €4,000,000
Source(s) of funding
- Public national budget
Type of funding
- Direct funding (grants, subsidies, or self-financed projects by private entities)
Non-financial contribution
No
Impacts and Monitoring
Environmental impacts
- Climate change
- Storm / wave induced erosion and flooding
- Expected storm / wave induced erosion and flooding
- Environmental quality
- Improved soil quality
- Expected improved soil quality
- Water management and blue areas
- Enhanced protection and restoration of freshwater ecosystems
- Achieved enhanced protection and restoration of freshwater ecosystems
- Green space and habitat
- Increased conservation or restoration of ecosystems
- Achieved increased conservation or restoration of ecosystems
- Increased number of species present
- Expected increased number of species present
- Increased presence and recovery of wild species
- Expected increased presence and recovery of wild species
Economic impacts
- Unknown
Socio-cultural impacts
- Unknown
Type of reported impacts
Presence of formal monitoring system
Yes
Presence of indicators used in reporting
Yes
Presence of monitoring/ evaluation reports
Yes
Availability of a web-based monitoring tool
Yes
Potential risks of implementation and trade-offs
Unknown
References
1.
Friends of the Detroit River (n.d.). Hennepin Marsh. Accessed on September 11, 2024, [Source link];
2.
Herpetological Resource and Management, LLC (2023). Hennepin South Marsh Amphibian and Reptile Post-Restoration Monitoring Report . Accessed on September 10, 2024, [Source link];
3.
ECT (2021). Habitat Restoration Construction Commences at Detroit River’s Hennepin Marsh. Accessed on September 10, 2024, [Source link];
4.
ECT (n.d.). Detroit River Habitat Restoration Protects Marsh from Erosion. Accessed on September 10, 2024, [Source link];
5.
Kasuba, J. (2021). Restoration of South Hennepin Marsh to enhance fish, wildlife habitat. News-Herald, Accessed on September 10, 2024, [Source link];
6.
Stoneco (n.d.). Hennepin Marsh Restoration Grosse Ile, MI. Accessed on September 10, 2024, [Source link];
7.
Wikipedia contributers (n.d.). Grosse Ile Township, Michigan. Wikipedia, Accessed on September 10, 2024, [Source link];
Hennepin Marsh
https://www.detroitriver.org/glri-projects/hennepin-marsh
Vegetated shoal within restoration area providing refugia for herpetofauna and other wildlife.
Ref.2
Hennepin South Marsh following restoration activities.
Ref.2
A Midland Painted Turtle (Chrysemys picta marginata) basking within the restoration area.
Ref.2
Hennepin Marsh
https://www.stoneco.net/project-gallery/hennepin-marsh-restoration
Hennepin Marsh
https://www.stoneco.net/project-gallery/hennepin-marsh-restoration
Information about this nature-based solution was collected as part of the Naturescapes project funded by the European Union under Grant Agreement No 101084341.