Abbott Marshlands Invasive Species Removal & Tidal Wetland Restoration

Mercer County’s John A. Roebling Memorial Park is home to the northernmost freshwater tidal marsh on the Delaware River, the Abbott Marshlands. This area contains valuable habitat for many rare species. Unfortunately, the area has experienced a significant amount of loss and degradation, partially due to the introduction of the invasive plant, Phragmites australis. The Mercer County Park Commission contracted Princeton Hydro to conduct a multi-year, multi-phased restoration of these important freshwater tidal wetlands. This ecosystem restoration aims to:

• Reduce and control Phragmites australis in Roebling Park’s freshwater tidal wetlands and increase the presence of desirable native marsh vegetation;
• Increase plant diversity and improve habitat for marsh species, including several threatened and endangered species in the Park;
• Enhance public, passive recreational opportunities in the Park, such as kayaking, bird watching, and fishing by improving access to the water, restoring navigable channels, improving the trail system; and
• Improve visitor experience to the Park and increase interpretive opportunities by cultivating a native plant community and enhancing the viewshed.

Princeton Hydro conducted a Floristic Quality Assessment to identify invasive areas and to establish a baseline for the restoration efforts. Princeton Hydro also performed hydrologic monitoring to understand tidal stage elevations. From 2018-2019, Princeton Hydro completed application of herbicide treatment on the invasive Phragmites in the tidal wetland.  In the Winter of 2019-2020, 46 acres of phragmites was cut and rolled with our Marsh Master using a modified steel roller attachment. The phragmites was then removed by raking, which in turn exposed the marsh plain’s substrate and seedbank to promote germination of the native marsh vegetation. Extensive areas of wild rice, mud plantain, broad leaved cattail, water purslane, pickerelweed, and arrow arum colonized the areas formerly overtaken by phragmites within the first growing season after the marsh plain was exposed.  

The next phase of this project will include designs for 500 linear feet of living shoreline, a freshwater mussel bed and a sustainable boat launch as part of the restoration design.