Coonamessett River Bog Restoration and Bridge Replacement, Falmouth, MA

Ecosystem Restoration & Mitigation
Dam Removal & River Restoration

June, 2020


Additional Highlights

Phase 1
• Dam Removal: 400ft
• New 400ft Boardwalk
• Invasive species control
• Adaptive Management
• Realignment of 0.7 miles of river

Phase 2
• Construction of a new massDOT bridge on John Parker Road over the river
• Nature-based fish passage techniques
• Restoration of more than 2,500 linear ft of stream channel to enhance fish passage and habitat

Environmental BenefitS

• Two dams removed
• Provided river herring with full access to 2.2 miles of free-flowing river
• A new, fish passage-friendly culvert under John Parker Road
• Improved river herring access to spawning and rearing habitats in 158-acre Coonamessett Pond
• 4,600 linear feet of river habitat restored and 56 acres of former agricultural cranberry bog restored to species-diverse natural wetlands

Phase 1 and Phase 2 Summary

Phase 1 – This phase was completed in early 2018, and included the removal of Lower Bog dam, installation of a public access boardwalk, reconstruction of the river channel, and restoration of 17 acres of wetlands.

The work consisted of the conversion of the cranberry platform to a more
naturalized wetland surface as well as the restoration of a free-flowing and naturalized river channel. This phase included the removal of Swift Crossing Dam and the installation of a 400ft long boardwalk where the dam once stood.

Phase 2 – This part of the project included the removal of Middle Bog dam, installation of a public access boardwalk and restoration of 39 acres wetlands by removing former commercial cranberry bogs. In addition, the replacement of three failing culverts with a large box culvert will allow migratory fish to access their upstream habitat, including the 158-acre Coonamessett Pond.

Restoration focused critical fish passage barriers along the lower mile of the river, including:

Middle Bog Dam – This control structure was in the middle of a valley-spanning berm that separated the inactive Lower Bog with the actively cultivated Middle Bog. The flow control was set to hold water in Middle Bog at a higher elevation than that in Lower Bog. This resulted in flooding of Middle Bog during certain times of the year and a vertical drop of several feet between the two bogs that presented a barrier to fish passage. The goal at this site was to improve fish
passage while maintaining water needed for the cultivation of cranberries until the upper bogs could be decommissioned.

John Parker Road – A series of three culverts conveyed flow under the built-up roadway, separating Middle Bog and Upper Bog. The cranberry bogs on either side of John Parker Road were being actively farmed organically. The culverts under the road were undersized and in poor condition, resulting in flow restrictions and fish passage problems.

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