North River Farms Wetland Restoration Project

The goal of wetland restoration/creation projects is to successfully construct a system that exhibits the same structure and beneficial functions as a targeted wetland community in the most efficient manner possible. Poor site selection, inappropriate designs and inefficient implementation will result in restorations that are much too expensive and fall short of achieving target ecosystem services, whether the restoration/creation project is required for compensatory mitigation or a volunteer effort.

In late 2002, in an effort to advance the understanding of design and construction techniques used in restoration in eastern NC, faculty from the Departments of Biological and Agricultural Engineering (BAE), Soil Science (SSC), and Forestry and Environmental Resources (FER) at North Carolina State University (NCSU) teamed with the NC Wetland Reserve Program (NCWRP, now the Ecosystem Enhancement Program (NCEEP)) and the North Carolina Coastal Federation (NCCF). Through a grant from the NC Clean Water Management Trust Fund (CWMTF) NCCF had purchased North River Farms in Carteret County, NC (White Oak River Basin, DWQ subbasin 03-05-04), which was approximately 2400 ha (6,000 acres) in size, in an effort to restore wetland function to this land that had been drained for agricultural row-crop production. In addition, restoration was seen as a measure that would improve water quality to the nearby North River, which was the receiving body of water for a large portion of the drainage water originating from North River Farms and nearby Open Grounds Farm.

The NCWRP/NCEEP supported Phase I of the project, which included funds for the design and construction of 100 ha (250 acres) of non-riverine wet hardwood wetland, post-construction monitoring of that site and a reference wetland community, pre-construction monitoring of a 43 ha (106 acre) Phase II stream and wetland complex, and design of that system. NCEEP then funded the construction of the tidal marsh portion of the Phase II effort and subsequent post construction monitoring of that area. None of this work, however, was undertaken for compensatory mitigation.

Since 2002,  this NCSU team has developed restoration designs, provided construction oversight, and conducted restoration research for 145 ha (356 acres) of wetlands and over 2600 m (8500 ft) of freshwater and tidal streams at North River Farms. Wetland communities restored included 123 ha (304 acres) of non-riverine wet hardwood, 14 ha (35 acres) of tidal marsh, and 7 ha (17 acres) of riparian wetlands.

The main goal of the effort has been to improve downstream water quality in the North River estuary by reducing drainage outflows and diverting agricultural drainage water from an adjoining farm across the restoration. However, wetland restoration at this site has been unique because it has employed innovative and varied designs, several of which were compared in side-by-side plots for hydrologic response. After almost 10 years of research, important findings concerning restoration design, construction techniques, and restoration success at the site have emerged. These findings will be useful to enhance the success of future NCEEP restorations. This endeavor has also been supported (at least in part) by 8 faculty, 3 research technicians, 10 graduate students and five undergraduates during this period, and resulted in numerous graduate theses, presentations and proceedings papers at professional meetings and conferences.

Current Research

With funding from an U.S. EPA 319 grant, the research at North River Farms will continue through 2012. The team is intensively monitoring the tidal marsh portion of Phase II. New techniques are being used to create a more accurate mass balance for nitrogen entering and leaving the marsh to quantify the amount of nitrogen removed by restored salt marsh systems. Doppler velocity meters and trapezoidal flumes are being used to monitor the flow. Newly available UV-visual spectrophotometers are  used to monitor the water quality multiple times per hour.

We are also working with the U.S. Geologic Survey to monitor greenhouse gas emissions from the restored tidal marsh to determine if these systems can be managed to be a net carbon sink.  In 2012, we also worked with the USGS to install 12 permanent benchmark rods to measure relative elevation change of the marsh sediments with a device known as a Surface Elevation Table (SET).  These measurements will help improve our understanding on the ability of restored marshes to adjust to sea-level rise.

Map that highlights the North River Farms wetland restoration area (NCDENR, 2001)
Partners for project – North Carolina Ecosystem Enhancement Program, the North Carolina Coastal Federation, The U.S. Environmental Protection Agency, and the U.S. Geologic Survey