HARBOR HEMI-MARSH
ASHTABULAWATERFRONT | RESILIENCE/CLIMATE ADAPTATION | BENEFICIAL USE | MONITORING
Status: Constructed
The Harbor Hemi-Marsh project along the shores of Lake Erie in Ashtabula, Ohio is one of the pioneering efforts in the Great Lakes to establish a partially-open wetland system using dredged material through the Section 204 program.
A submerged sill complements the existing harbor breakwater to protect the placed dredged sediment and facilitate wetland development. Over multiple cycles, the area within the sill will be filled with local dredged material to support wetland and lake-floor habitats, benefiting both aquatic and terrestrial wildlife and creating recreational and tourism opportunities for the region.
Departing from the traditional practice of confined sediment placement, the project emphasizes the economic and ecological value of a more open, sensitive, and passive coastal infrastructure. While maintaining a conservative level of protection, the design collaborates closely with the USACE to maximize openness while adhering to acceptable project risk levels.
This partially-open design allows for occasional, ecologically necessary disturbances that enhance wetland complexity and ensure a vital hydrological connection to the nearshore. Sediment placement will occur over three or four dredge cycles, spaced every two to three years. This phased approach enables adaptive management, with each cycle's sediment placement informed by field-quantified factors like the angle of repose and settling rate. Post-placement monitoring will guide subsequent cycles, fostering a responsive management approach.
The strategies developed from this project offer scalability for both larger and smaller ports. Currently under construction, the project employs the dynamic hemi-marsh concept, with initial placement cycles already underway.
Learn more:
- Visit the Healthy Port Futures website
Press:
- As Great Lakes warm, collaboration and Indigenous self-determination are keys to adapting
- Beneficial reuse of dredged sediment in Ashtabula
- Ashtabula Harbor Dredge Management: Dredge to Wetlands Habitat
Client: Great Lakes Protection Fund
Collaborators:
- USACE- Buffalo District
-
Ohio EPA
- University of Michigan St. Anthony’s Falls Laboratory
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