Environmental reviews and case studies:The North Carolina Wetland Assessment Method (NC WAM): Development of a rapid wetland assessment method and use for compensatory mitigation
The North Carolina Wetland Assessment Method (NC WAM) was developed from 2003 to 2007 by a team of federal and state agencies to rapidly assess the level of wetland function. NC WAM is a field method which is science-based, reproducible, rapid, and observational in nature used to determine the level of wetland function relative to reference for each of 16 North Carolina general wetland types. Three major functions (Hydrology, Water Quality, and Habitat) were recognized along with 10 sub-functions. Sub-functions and functions are evaluated using 22 field metrics on a field assessment form. Data are entered into a computer program to generate High, Medium, and Low ratings for each sub-function, function, and the overall assessment area based on an iterative Boolean logic process using 71 unique combinations. The method was field tested across the state at more than 280 sites of varying wetland quality. Examples are presented for the use of NC WAM for compensatory mitigation notably to calculate functional uplift from wetland enhancement. Calibration and verification analyses to date show that the results of the method are significantly correlated with long-term wetland monitoring data and NC WAM has been verified for one wetland type (headwater forest) using these data.