Wetland Restoration and Creation Design to Restore Wetland Functions

Abstract

Federal and state regulatory programs in the Chesapeake Bay watershed require wetland mitigation to obtain a permit for wetland impacts. The loss of wetlands in a watershed through permitted activities diminishes its capacity to perform important habitat, water retention and dissipation, and biogeochemical cycling functions. Past attempts at wetland mitigation have produced wetlands that meet the three parameters (a predominance of wetland plants, wetland hydrology, and wetland soils) of a jurisdictional wetland, but little thought was put into whether the mitigation site was providing similar wetland functions to those wetlands impacted. Current research on wetland hydrogeomorphic (HGM) setting as well as HGM functional assessment models and other functional assessment approaches have provided incite on important characteristics that allow wetlands to provide certain functions. These characteristics are starting to be incorporated into wetland restoration and creation site design in hope that the mitigation site will not just mitigate for acreage, but also mitigate for loss of wetland function. Criteria for proper wetland mitigation design incorporate appropriate HGM setting, ability to reproduce hydroperiod and hydrodynamics, inputs of organic matter in forms that are partially decomposed and as coarse woody debris, macro- and micro-topography, and other characteristics that affect specific wetland functions. Mitigation criteria can be adjusted to address problems in a watershed by concentrating on characteristics that affect wetland functions that can help alleviate that problem.