Published Article/Report
- Gebo, N. A., and R. P. Brooks. 2012. Hydrogeomorphic (HGM) assessment of mitigation sites compared to natural reference wetlands in Pennsylvania. Wetlands 32:321-331.
The U.S. Environmental Protection Agency and U.S. Army Corps of Engineers completed revisions to the Mitigation Rule of the Clean Water Act in 2008. These revisions encourage states to carry out mitigation in a watershed context, prioritizing mitigation site design and placement by overall watershed need, to the extent appropriate and practicable (33 C.F.R. 332.3(c)). States are expected to establish monitoring programs and measureable performance standards for mitigation wetlands. In Pennsylvania, hydrogeomorphic (HGM)-based assessments involving 222 reference wetlands were used to compare mitigation wetland performance. For this study, 72 mitigation wetlands were sampled in 2007 and 2008 from three categories – Pennsylvania Wetland Replacement Program sites, Pennsylvania Department of Transportation mitigation banks, and permit required compensatory mitigation sites. Mitigation wetlands were intensively sampled using a Level 3 - Intensive methodology developed by Riparia. Field data and GIS computed variables were used to derive the scores of 10 HGM functional capacities. Overall, mitigation sites displayed lower potential to perform a characteristic wetland function than reference wetlands. Depressions show the greatest discrepancy, while fringing sites showed the least amount of difference from reference scores. Mitigation site size, age, and type were not significant factors in functional capacity index scores.