Text Size:   A+ A- A   •   Text Only
Find     
Site Image
HGM Guidebooks

 
Blue Camas graces this Willamette Valley Wet Prairie;
less than 1% of the original prairie wetlands remains.
Photo by John Christy.
.
The hydrogeomorphic (HGM) approach to assessment of wetland and riparian functions is based on two main concepts:
 
First, wetlands in a region that share the same landscape setting and hydrologic regime will support similar functions.
 
Second, levels of function at one site can be compared on a scale to functions of multiple reference sites of the same type.
 
For statewide application, we have also released a framework for future development of additional wetland and riparian function assessment tools.
 
Following this approach, the various landscape settings and hydrologic regimes that influence wetland functions have been classified for each of 10 ecoregions in Oregon. The guidebooks just released address two of these classes in the Willamette Valley. Data has been collected from 109 reference sites in this area to characterize the scale, from low to high levels, of each of 13 functions.
 
The three documents cited below are the culmination of over three years of effort led by our contractor, Paul Adamus. We also appreciate the contributions of our technical advisory committee and over 50 volunteers in collecting reference site data and reviewing draft documents. The Oregon Department of State Lands received grant funds from the US Environmental Protection Agency to support this work, in order to advance understanding of regionally important wetland functions.
 
The Department will be conducting further training and testing of the HGM approach, and will be exploring future options to use this approach to improve mitigation success. We encourage experimental application of these methods by wetland scientists and would appreciate feedback from users on the utility of the methods, areas that may need clarification, and suggestions for how the methods may eventually be used in a regulatory context, or other agency applications. Please send such comments to Dana Field, 503-986-5238 or Dana.Field@dsl.state.or.us.
 
  1. Adamus, P.R. and D. Field. 2001. Guidebook for Hydrogeomorphic (HGM) - based Assessment of Oregon Wetland and Riparian Sites. I. Willamette Valley Ecoregion, Riverine Impounding and Slope/Flat subclasses. Volume 1A: Assessment Methods. 146pp. This volume contains a key to the Willamette Valley HGM classification, as well as field forms, instructions, and a glossary for evaluating wetland/riparian sites in the Willamette Valley. To complete a site evaluation you will also need data from the CD.
  2. Adamus, P.R. 2001. Guidebook for Hydrogeomorphic (HGM) - based Assessment of Oregon Wetland and Riparian Sites. I. Willamette Valley Ecoregion, Riverine Impounding and Slope/Flat subclasses. Volume 1B: Technical Report. 86pp. This volume describes the development of the functional models including the selection of indicators of function, selection of reference sites, and the results of preliminary testing of the consistency and comparability of assessments using the indicators. It also discusses use of reference data for developing performance standards for wetland mitigation projects.
  3. Adamus, P.R. 2001. Guidebook for Hydrogeomorphic (HGM)- based Assessment of Oregon Wetland and Riparian Sites: Statewide Classification and Profiles. 168pp. This guidebook presents a framework for future development of functional models throughout the state. It identifies 14 HGM wetland/riparian subclasses occurring in 10 different ecoregions. It describes 13 different functions expected to be provided at some level by those sites, and also describes their sensitivities to various human & natural disturbances. This volume also presents a synopsis of the HGM classification and function assessment method to other classifications and methods in use throughout the Pacific Northwest.
  4. Compact disc. The disc contains copies of the text of all 3 documents as pdf files. The disc also contains actual wetland/riparian reference site data files, maps, and photos of the references sites. It contains land cover maps and historical vegetation maps for the Willamette Valley, which will be necessary for those conducting wetland functional assessments using the reference-based method. The CD also contains a searchable bibliography of over 1600 references on wetland/riparian literature for the Pacific Northwest, compiled by Paul Adamus. 224 MB.
 
 
 
 
 
 
 
 
Back to the Top