Turtles on a tree branch in Killingworth wetlands

Killingworth Reservoir Wetland Mitigation


Connecticut, USA

Increasing demands on the Connecticut Water Company Guilford system required the Connecticut Water Company to expand their supply system yield by raising the dam at the Killingworth Reservoir, a supply impoundment located on Blueberry Brook.

As mitigation for unavoidable impacts to the environment, in particular, the flooding and filling of wetlands surrounding the current reservoir and dam, a programme of wetland enhancement and inventory was undertaken. The total area of existing wetlands impacted by the project was 5.2 acres of littoral fringe wetlands that were originally created by the reservoir. SLR developed a mitigation strategy to offset the wetland impacts, developed the wetland design plans, oversaw construction, and is implementing the thru-year monitoring programme.

Mitigation wetlands total 6.2 acres, all of which were created along the fringe of the modified reservoir. These wetlands were designed to mimic the natural littoral fringe wetlands that were impacted. They consisted of three wetland communities including floating-leaved aquatic beds (e.g. deep marsh), emergent marsh (e.g. shallow marsh), and scrub-shrub wetlands.

Construction of the 6.2-acre mitigation wetland was completed under the supervision of SLR wetland scientists. The project team monitored the construction of the wetlands, including the proposed grading requirements, wetland soil amendments, hydrology, and wetland plantings. Subsequently, SLR undertook a postconstruction monitoring programme in 2015 to ensure that the created wetlands met the intended design goals and permit conditions.

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