Watershed, Stormwater, & Integrated Water Management
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- Upper Connecticut River Habitat Restoration Plan
the challenge In May of 2001, the U.S. Congress authorized the U.S. Army Corps of Engineers (USACE) to conduct an expedited reconnaissance study, or 905(b) assessment of the Upper Connecticut River watershed in New Hampshire and Vermont to identify streambank restoration opportunities. Preliminary investigations by the Connecticut River Joint Commission (CRJC) identified numerous erosion sites of concern along the Upper Connecticut River. Seven of these were deemed worthy of further investigation because of a demonstrated link between restoration opportunities and benefits to aquatic resources in the Federal interest. The New England District USACE then contracted the Bioengineering Group to further assess these sites and develop recommendations for bank restoration and stabilization using bioengineering approaches.
the interdisciplinary approach Six of the seven sites identified by the CRJC are within U.S. Fish and Wildlife Service National Fish and Wildlife Refuge Special Focus Areas, river reaches noted as having substantial or unique natural diversity. Most notable is the presence of dwarf wedge mussels, an endangered species whose habitat is degraded by excessive siltation.
Common problems identified during field reconnaissance included minimal or absent riparian buffers at most sites, upstream tributary influences, and poor stormwater management. Water level fluctuations related to a downstream hydroelectric facility were identified as a possible cause of bank slumping at one site. Proposed concept designs were tailored to the dominant geomorphic processes and the prevailing hydraulic and hydrologic conditions evident at each site. Most recommendations included establishment, or enhancement, of forested riparian buffers in conjunction with bioengineering bank stabilization techniques. At some sites, rock vanes or bendway weirs were recommended owing to the prevalent geomorphic conditions .
the resultsBioengineering Group developed conceptual solutions and cost estimates for each of the identified problem areas and presented their recommendations and cost estimates at a stakeholder meeting and facilitated subsequent stakeholder meetings and discussions by providing technical and planning consultation for feasibility phase analyses and working to build consensus for moving forward.