Studies Related to Compensatory Mitigation

Evaluation of Success Criteria and Restoration Techniques to Promote Aquatic Biota in NC Mitigation Wetlands

This U.S. EPA funded study is being conducted in collaboration with the NC Wildlife Resources Commission (WRC). Wetland mitigation in North Carolina currently focuses on the success of site hydrology and vegetation, defined by planted tree stem survival rates. This study proposes to investigate the condition of the aquatic biota, specifically amphibian and macroinvertebrate communities, found in mitigation sites. The results will be compared to amphibian and macroinvertebrate communities found in natural wetlands and wetlands being restored by the WRC. The WRC restored wetlands are using tree removal and prescription burns to develop habitat that will encourage the establishment of amphibian communities. The goal of this study is to ultimately be able to make recommendations to wetland mitigation land managers on ways to restore and manage wetland mitigation sites to promote aquatic biota. Secondary goals are to refine macroinvertebrate survey methodology for North Carolina wetlands and to develop metrics from the results that can be used as accurate indicators of site condition. Field surveys for this project have begun and will continue through the summer of 2013.

Environmental Law Institute Mitigation Study

This study is supported by the Environmental Law Institute (ELI), a non-profit organization, and is being done in collaboration with NC State University. The goal of this study is to evaluate the ecological differences between wetland mitigation projects completed by the three major provider types in North Carolina: Mitigation Bank, In-Lieu Fee, and Private-Permittee. Wetland mitigation in NC can be done through the purchase of mitigation credits from a private mitigation bank, through a fee paid to the NC Ecosystem Enhancement Program (EEP) which in turn manages wetland mitigation sites (In Lieu Fee), or privately on the permittee’s own property. Thirty mitigation projects representing the three provider types that were considered to have been successful in terms of hydrology and vegetation by regulators were randomly chosen across the state for this study. Ecological surveys were conducted during the 2012 growing season on the vegetation, hydrology, condition of the surrounding landscape, and soil and water quality at each site. The results of this study are currently being analyzed and will be completed later this year.

Defining Limits for Small Stream Biological Criteria for Use in Stream Restoration Monitoring

Biological criteria are developed by evaluating the diversity, abundance, and pollution sensitivity of organisms that inhabit streams. This information can then be used to assess various impacts of both point source and nonpoint source discharges. Small (1st and 2nd order) streams make up 70-85% of the stream network in North Carolina, but until recently NC DWR did not have a way to assign biological criteria to these small streams.  In 2009, this changed based on research done by NC DWR’s Biological Assessment Unit; however, the criteria can only be assigned during a small sampling window (April and May) and there was very little testing of streams with less than a ½ square mile drainage area.  This project is designed to do two things: 1) determine the lower size limits for streams that can be assessed, and 2) determine if there are other times of the year where assessments can be made in addition to April and May.  So far, the results indicate that the method is limited to perennial streams that have enough water to properly use the sampling equipment.  Data collection is complete and analysis is still being conducted to determine whether the sampling window can be expanded and if so, to what extent.