Stream and Wetland Restoration

Walnut Brook

Walnut Brook RestorationThe North Jersey Resource Conservation and Development Council (NJRC&D) contracted Princeton Hydro, LLC (Princeton Hydro) to conduct streambank stabilization and wetland mitigation design services on Walnut Brook on the property known as Dvoor Farms located in Raritan Township, Hunterdon County, New Jersey.

Walnut Brook was actively eroding and re-meandering after a history of channelization for agriculture. The geomorphic readjustment process had been accelerated in recent years by heavy rain and flood events. Channel incision had disconnected the stream from its floodplain and meander development threatened the park. Riparian vegetation planting, wetland creation, floodplain enhancement and unique channel stabilization techniques were developed to address these issues.

The overriding objectives of the project were to enhance the functions and values provided by the floodplain and to stabilize the channel of Walnut Brook. The wetland creation component provides flood storage, which in turn fosters the development of the wetland communities. A suite of channel stabilization measures were employed to protect park infrastructure and to demonstrate the use of alternative methods that could be applied elsewhere in the state. The restoration project involved the creation of three acres of emergent wetland, restoration of the Walnut Brook floodplain and riparian areas (approximately 10 acres), and stabilization of over 700 linear feet of eroding banks. The wetland element of the project was designed to increase the flood storage functions of the floodplain.

Princeton Hydro conducted detailed field investigation and data collection to guide the design. For the wetland component, monitoring wells were installed to characterize groundwater conditions and a water budget was developed to guide the wetland design to ensure that there would be an adequate supply of surface and groundwater to maintain the system as a functioning palustrine wetland.

The project won the 2010 AWRA Excellence in Water Resources Protection and Planning Award for exceptional stream restoration. The project also received the 2010 Governor’s Environmental Excellence Awards for Healthy Ecosystems.