Scientific Investigations Report 2005-5244

Using Hydrogeomorphic Criteria to Classify Wetlands on Mt. Desert Island, Maine—Approach, Classification System, and Examples

By Martha G. Nielsen, Glenn R. Guntenspergen, and Hilary A. Neckles

A black and white photograph of a snow-covered mountian rising from a grassy field.


A wetland classification system was designed for Mt. Desert Island, Maine, to help categorize the large number of wetlands (over 1,200 mapped units) as an aid to understanding their hydrologic functions. The classification system, developed by the U.S. Geological Survey (USGS), in cooperation with the National Park Service, uses a modified hydrogeomorphic (HGM) approach, and assigns categories based on position in the landscape, soils and surficial geologic setting, and source of water. A dichotomous key was developed to determine a preliminary HGM classification of wetlands on the island. This key is designed for use with USGS topographic maps and 1:24,000 geographic information system (GIS) coverages as an aid to the classification, but may also be used with field data.

Hydrologic data collected from a wetland monitoring study were used to determine whether the preliminary classification of individual wetlands using the HGM approach yielded classes that were consistent with actual hydroperiod data. Preliminary HGM classifications of the 20 wetlands in the monitoring study were consistent with the field hydroperiod data. The modified HGM classification approach appears robust, although the method apparently works somewhat better with undisturbed wetlands than with disturbed wetlands. This wetland classification system could be applied to other hydrogeologically similar areas of northern New England.

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Purpose and Scope

Previous Studies

Description of Study Area

Approach: Designing a Hydrogeomorphic Classification System


Assigning and Testing HGM Subclasses

Classification System for Wetlands on Mt. Desert Island

Preliminary HGM Classification System

Riverine Wetlands

Riverine–Upper Perennial



Depressional Wetlands




Depressional–No Ground-Water Input

Mineral Soil Flats

Organic Soil Flats

Tidal Fringe

Lacustrine Fringe


Application of Classification System

Dichotomous Key for the Identification of Wetland Subclasses

Expected Hydroperiod Characteristics

Example of Classifying Wetlands: A Test Case in Acadia National Park

Data Collection for the Test Wetlands

Hydrogeomorphic Classification without Hydroperiod Data

Evaluation of Preliminary Hydrogeomorphic Classification Using Hydroperiod Data

Comparison of Disturbed and Undisturbed Wetlands

Summary and Conclusions



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