A Regional Guidebook for Applying the Hydrogeomorphic Approach to Assessing Wetland Functions of Prairie Potholes

Abstract

Abstract : The Hydrogeomorphic (HGM) Approach is a method for developing functional indices and the protocols used to apply these indices to the assessment of wetland functions at a site-specific scale. The HGM Approach was initially designed to be used in the context of the Clean Water Act, Section 404 Regulatory Program, permit review to analyze project alternatives, minimize impacts, assess unavoidable impacts, determine mitigation requirements, and monitor the success of compensatory mitigation. However, a variety of other potential uses have been identified, including the determination of minimal effects under the Food Security Act, design of wetland restoration projects, and management of wetlands. This report uses the HGM Approach to develop a Regional Guidebook to: characterize ponded, herbaceous marshes of the glaciated Prairie Pothole Region; provide the rationale used to select functions of the ponded, herbaceous depressional marsh subclass; provide the rationale used to select model variables and metrics; provide the rationale used to develop assessment models; provide data from reference wetlands and document its use in calibrating model variables and assessment models; and outline the necessary protocols for applying the functional indices to the assessment of wetland functions.