The National Action Plan To Implement the Hydrogeomorphic Approach To Assessing Wetland Functions

This National Action Plan (Action Plan) identifies the strategy the U.S. Army Corps of Engineers, U.S. Department of Agriculture--Natural Resources Conservation Service, U.S. Environmental Protection Agency, U.S. Fish and Wildlife Service, Federal Highway Administration, and National Oceanic and Atmospheric Administration--National Marine Fisheries Service will follow to implement the Hydrogeomorphic Approach for Assessing Wetland Functions (HGM Approach) through the development of regional guidebooks. This is a plan to guide Federal agency activities and inform the public on how the federal agencies will be developing regional guidebooks for use with the HGM Approach. The HGM Approach is a procedure for measuring the capacity of a wetland to perform functions. It was designed to satisfy the need for better information on wetland functions within the programmatic requirements of the Clean Water Act Section 404 regulatory program. Information obtained using the HGM Approach can assist project proponents and regulators in assessing the level of environmental impact of a proposed project, in determining the appropriate level of regulatory review, and in assessing compensatory mitigation required for offsetting environmental impacts. The hierarchical and modular nature of the approach makes it adaptable to a variety of other regulatory, planning, management, and educational situations where information on wetland functions is needed.

The HGM Approach is characterized and differentiated from other wetland assessment procedures in that it first classifies wetlands based on their hydrogeomorphic characteristics (i.e., landscape setting, water source, hydrodynamics), second it uses reference to establish the range of functioning of the wetland, and third it uses a relative index of function, calibrated to reference wetlands, to assess wetland functions. This increases the resolution, allows for replicability, and reduces the amount of time needed to conduct the assessment. The HGM Approach utilizes reference wetlands as the means for establishing the scale, or index, against which other wetlands of the same type in a particular geographic area (reference domain) can be compared to determine their functional capacity. Reference wetlands are selected to reflect the range of conditions in a particular geographic area that a particular wetland type may exhibit, from relatively undisturbed to highly degraded.

Under the HGM Approach, national guidebooks are being developed for each of the major classes of wetlands: riverine, depressional, slope, flats (mineral soil and organic soil), and fringe (estuarine and lacustrine). The national guidebooks provide a template for developing regional guidebooks for regional wetland subclasses. Regional guidebooks include a definition and characterization of the regional wetland subclass, models for assessing selected functions, and methods for applying the assessment models. Interdisciplinary teams of wetland specialists from Federal, State, Tribal, and local agencies, as well as the private sector and academia, will coordinate the development of regional guidebooks. To ensure the technical accuracy of the effort, regional guidebooks will be developed following specific protocols and subjected to a rigorous peer review process involving wetland experts from Federal, State, Tribal, and local agencies, academia, and the private sector. Regional guidebooks will be published initially as an operational draft for a two year period to provide agencies, academia, the private sector, and the general public an opportunity to review, apply, and comment on the procedure. Issues raised during this time will be addressed in the final publication. To ensure the best available science is incorporated, the final regional guidebooks will be subject to review and revision for a period not to exceed five years.

Regional guidebooks are being developed in three phases: a pilot phase, an expanded nationwide effort to develop 15 to 20 additional regional guidebooks, and an effort to develop additional models based on priorities established by the Federal agencies. Efforts will be prioritized so that at the end of Phase II there are a sufficient number of regional guidebooks to address 80 percent of the permit workload for wetlands requiring a functional assessment. Given limited agency resources, such an undertaking will require the coordinated participation of Federal, State, Tribal, and local agencies, as well as individuals from academia, and the private sector. State agencies and others who choose to initiate development of regional guidebooks on their own will be encouraged to coordinate with the Federal agencies to ensure consistency, quality, and maximum applicability by Federal, State, Tribal, and local agencies in their wetland programs.

Technical support and coordination for the development of the HGM Approach is being provided by the U.S. Army Engineer Waterways Experiment Station (WES). To facilitate development of the regional guidebooks, WES, in conjunction with other Federal and State agencies and other wetland experts, has developed, and will continue to develop, the necessary support documents, technical information and training materials. Experts from WES will oversee the development of regional guidebooks to ensure consistency and accuracy in these efforts.

To support implementation of the HGM Approach, the Federal agencies will be preparing a policy statement to clarify the application of the HGM Approach within the Section 404 regulatory program and the Food Security Act Swampbuster program. The HGM Approach is a procedure for determining the level at which a proposed project will affect wetland functions. An assessment using the HGM Approach is not a substitute for the Section 404(b)(1) Guidelines or the public interest review; rather the HGM Approach is a tool to be used in the permit review process. It may be used to rapidly and consistently determine the level of environmental impact of a proposed project, to compare project alternatives, to identify measures that would minimize environmental impacts, to determine mitigation requirements, and to establish standards for measuring mitigation success. The policy statement will indicate the manner in which such applications can provide greater certainty and consistency within the decision making process.

II. Overview of the Hydrogeomorphic Approach
The Hydrogeomorphic Approach for Assessing Wetland Functions (HGM Approach), developed by scientists at the U.S. Army Engineer Waterways Experiment Station (WES), is a procedure for measuring the capacity of a wetland to perform functions. The procedure was designed to satisfy the need for better information on wetland functions within the programmatic requirements of the Clean Water Act Section 404 (Section 404) regulatory program. The HGM Approach is a tool that can be used in the alternatives analysis and in assessment of compensatory mitigation within the Section 404 permit review process. The hierarchical and modular nature of the approach make it adaptable to a variety of other regulatory, planning, management, and educational situations requiring the assessment of wetland functions.

The HGM Approach is characterized and differentiated from other wetland assessment procedures in that it first classifies wetlands based on their ecological characteristics (i.e., landscape setting, water source, hydrodynamics), second it uses reference to establish the range of functioning of the wetland, and third it uses a relative index of function, calibrated to reference wetlands, to assess wetland functions. HGM uses a hierarchical classification with seven major hydrogeomorphic wetland classes. These classes are : riverine, depressional, slope, flats (organic soil and mineral soil), and fringe (estuarine and lacustrine). The hydrogeomorphic classification is based on three fundamental factors that influence how wetlands function: position of the wetland in the landscape (geomorphic setting), water source (hydrology), and the flow and fluctuation of the water once in the wetland (hydrodynamics). Within a specific geographic area wetland classes can be further divided into regional wetland subclasses (e.g., vernal pools in California, prairie potholes in the northern plains states, and pine flatwoods in the southeastern U.S.). Classifying wetlands based on how they function narrows the focus of attention to a specific type or subclass of wetland, the functions that wetlands within the subclass are most likely to perform, and the landscape and ecosystem factors that are most likely to influence how wetlands in the subclass function. (Table 1.) This increases the accuracy of the assessment, allows for replicability, and reduces the time needed to conduct the assessment.

The HGM Approach includes a development phase and an application phase. The development phase is carried out by an interdisciplinary Assessment Team of wetland experts (A-team) and begins with the classification of wetlands into regional subclasses. The A-team then develops a functional profile that describes the physical, chemical, and biological characteristics (wetland functions) of the regional wetland subclass, identifies which functions are most likely to be performed, and discusses different ecosystem and landscape attributes and processes that influence each function. The functional profile is based on the experience and expertise of the A-team and information collected from reference wetlands. Reference wetlands are selected from a reference domain (a defined geographic area) and represent sites that exhibit a range of variation within a particular wetland type including sites that have been degraded/disturbed as well as those sites which have had little disturbance.

Source: Smith et al., An approach for assessing wetland functions using hydrogeomorphic classification, reference wetlands, and functional indices. U.S. Army Corps of Engineers Waterways Experiment Station, Technical Report TR WRP-DE-9. Vicksburg, MS. Oct. 1995.

The A-team next develops assessment models and calibrates them based on data collected from the reference wetlands. These models define the relationship between attributes and processes of the wetland ecosystem and surrounding landscape and the capacity of a wetland to perform a function. The assessment model results in a functional capacity index (FCI) (0-1.0), which estimates the capacity of a wetland to perform a function relative to other wetlands from the same regional subclass in the reference domain. The standard of comparison used to scale functional indices are reference standards, or the conditions under which the highest, sustainable level of function is achieved across the suite of functions performed by reference standard wetlands in a regional wetland subclass.

During the application phase of the HGM Approach, the assessment models in the regional guidebook are used to assess wetland functions. The context of the application may be the Section 404 permit review process, or in some other regulatory, planning, or management situation. The HGM Approach does not replace the need for delineating a wetland boundary, preclude the sequencing process, nor supercede the Section 404(b)(1) Guidelines analysis or public interest review. The HGM Approach is a tool that can be used in the alternatives analysis and is expected to be used on those permit actions which warrant a functional assessment for determining wetland impacts. Regulators will be able to use this procedure to rapidly and accurately determine the level of environmental impacts of proposed projects, compare project alternatives, identify measures that would minimize environmental impacts, determine mitigation requirements, and establish criteria for measuring mitigation success. As such, the procedure will be helpful in providing greater certainty and reduced permit review times thus allowing for expedited decision making.

The HGM Approach does not assign a value to wetland functions. Value represents the significance of wetland functions to society or individuals, and often reflects local priorities or policy issues beyond the scope of the HGM Approach. The functional capacity indices resulting from the HGM Approach cannot be equated to the societal or economic value of that wetland function. This information may be used when assigning values to wetland functions in terms of economic or other value units as required by the public interest review process.

III. Implementation Strategies of the HGM Approach

Note: * = Agency abbreviations are listed below

Five regional guidebooks are currently under development representing depressional wetlands (prairie potholes in the northern plains states and vernal pools in the Central Valley of California), riverine wetlands (low gradient streams in western Kentucky/Tennessee), flats (flats in the East Everglades of Florida), and flat/depressional mosaics in Florida. Table 3 identifies the current status of these regional guidebooks and their anticipated completion dates.

B. Phase II--Expanded Nationwide Effort

Phase II, initiated during 1996, consists of an expanded nationwide effort to develop regional guidelines in approximately 15-20 additional regional wetland subclasses. Regional guidebooks developed in Phase II will use the same protocol as described for Phase I. As identified in Table 3, efforts currently underway as part of Phase II include the development of assessment models for riparian systems, herbaceous depressional and slope wetlands in the northern Rocky Mountains, forested slope wetlands in New England, and coastal fringe wetlands of the Gulf of Mexico. In addition to the efforts being led by the Federal agencies, there are also efforts in regional guidebook development being led by various states under EPA's State Grant Program. These efforts to date are listed in Table 4. However, it should be recognized that expanded efforts in this Phase will not address all regional wetland subclasses. The number of efforts initiated is dependent upon the availability of personnel, time, and financial resources.

Table 4.--Status of Other HGM Efforts, Funded by the U.S. Environmental Protection Agency (including EPA State/Tribal Wetland Grant Program)

Component	Contributing agency(ies)	Product	Projected completion	Current status
Regional Riverine Guidebooks:
Low gradient riverine wetlands in the lower Mississippi River Valley	EPA/COE-WES	Operational Draft	Sep. 98	Initiated Apr 97
Riverine Wetlands of the Santa Margarita Watershed in Southern California	EPA	Operational Draft	Oct. 98	Draft complete, undergoing peer review prior to workshop review
Riverine/slope wetlands of southeast Alaska	Alaska DEC/SGP	Operational Draft	Oct. 97	Draft undergoing peer review
Riverine wetlands in 1st-- 2nd order headwater reaches in Pennsylvania and Maryland	EPA	Operational Draft	Mar. 99	Initiated May 94
Riverine wetlands along broad floodplains associated with streams greater than 2nd order in Pennsylvania and Maryland	EPA	Operational Draft	Mar. 99	Initiated May 94
Flow through and impounded riverine wetlands in Washington	Washington Dept of Ecology/SGP	Operational Draft	Jan. 98	Workshop held May 97
Low gradient riverine wetlands of the Great Colorado Plateau and Rocky Mt. region	Utah Governor's Office of Planning/SGP	Operational Draft	Mar. 98	Data collection
Riverine wetlands of Kenai watershed Alaska	AK DEC/FWS/ Kenai Peninsula Borough/SGP	Operational Draft	Sep. 98	Fieldwork Jul 97
Regional Slope Guidebooks:
Slope wetlands in Pennsylvania	EPA	Operational Draft	Dec. 98	Initiated May 94
Regional Depression Guidebooks:
Flowthrough and closed depression wetlands in Washington	Washington Dept of Ecology/SGP	Operational Draft	Jan. 98	Workshop held May 97
Depression wetlands in Pennsylvania	EPA	Operational Draft	Dec. 98	Initiated May 94
Depression wetlands in Guam	EPA	Operational Draft	Dec. 99	Initiate in Aug 97
Regional Flats Guidebooks:
Flats wetlands on discontinuous permafrost in interior Alaska	AK DEC/NRCS/DOA/SGP	Operational Draft	Jul. 97	Workshop held Apr 97
Regional Fringe Guidebooks:
Tidal freshwater marshes of the Hudson River, New York	NY DEC/COE/Hudson River Improvement Fund/SGP	Operational Draft	Dec. 98	Pre-draft guidebook completed
Other:
Characterization and Colorado functional assessment of reference wetlands of the southern and central Rocky Mountains

Note: * = Agency abbreviations are listed below:

COE-WES--U.S. Army Corps of Engineers.

EPA--U.S. Environmental Protection Agency.

SGP--EPA's State/Tribal Wetland Grant Program.

NRCS--U.S.D.A. Natural Resources Conservation Service.

AK DEC--Alaska Department of Environmental Conservation.

NY DEC--New York Department of Environmental Conservation.

DOA--Department of the Army.

 

In addition to the development of regional guidebooks, the Corps and the other Federal agencies, will work together during Phase II, to develop necessary guidance on how the HGM Approach may be applied in the review of Section 404 permit applications. The intent of the guidance is to clarify how information from an assessment can be used to determine the level of environmental impacts a proposed project may cause and the appropriate regulatory response.

C. Phase III

Based on the needs of the Federal agencies and work conducted to date by others, the agencies will establish a priority listing of additional models to be developed.

VII. Funding

Primary funding for the Federal effort to develop the HGM Approach has been and will continue to be provided through the Corps, with additional support being provided by other federal agencies, including EPA, NRCS, FWS, NMFS, and FHWA. As development of the approach continues, limited Federal funds will be available for the development of each regional guidebook to support tasks such as the collection of data, training, and technical workshops. The cost for developing regional guidebooks is expected to vary depending on the scope of the effort and the level and nature of participation by Federal, State, Tribal and local agencies and the private sector. For State, Tribal and certain local efforts, EPA's State Wetlands Grant Program has made funding available for those agencies wishing to pursue an HGM Approach within their wetlands program. Interested State, Tribal and local agencies should contact the local EPA office for further information.

References

Brinson, M.M. 1993. A Hydrogeomorphic Classification for Wetlands. Wetland Research Program Technical Report WRP-DE-4. U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Brinson, M.M., F.R. Hauer, L.C. Lee, W.L. Nutter, R.D. Smith, D. Whigham, 1995. Guidebook for Application of Hydrogeomorphic Assessments to Riverine Wetlands (Operational Draft). Wetland Research Program Technical Report WRP-DE-11. U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Davis, M.M., E.J. Clairain, Jr, W. Ainslie, M. Gilbert, M.A. Schwinn, M. Sheehan, G. Sparks, K. Trott, and M. Whited. May 1996 (Draft). Development of Regional Wetland Subclass HGM Functional Assessment Model Guidebooks.

Smith, R.D. 1993. A Conceptual Framework for Assessing the Functions of Wetlands. Wetland Research Program Technical Report WRP-DE-3. U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Smith, R.D., A. Ammann, C. Bartoldus, and M.M. Brinson. 1995. An Approach for Assessing Wetland Functions Using Hydrogeomorphic Classification, Reference Wetlands, and Functional Indices. Wetland Research Program Technical Report WRP-DE-9. U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.

Clairain, E.J., Jr. (ed). In prep. Guidelines for Developing Hydrogeomorphic Approach Regional Guidebooks. Wetland Research Program Technical Report WRP-DE-__. U.S. Army Waterways Experiment Station, Vicksburg, MS.

Appendix A
Definition of Terms
Assessment Model: A simple model that defines the relationship between ecosystem and landscape scale attributes and processes and functional capacity of a wetland. The model is developed and calibrated using reference wetlands from a reference domain.
Assessment Objective: The reason why an assessment of wetland functions is being conducted. Assessment objectives normally fall into one of three categories. These include: documenting existing conditions, comparing different wetlands at the same point in time (e.g., alternatives analysis, and comparing the same wetland at different points in time (e.g., impact analysis or mitigation success).
Assessment Team (A-Team): An interdisciplinary group of regional and local scientists responsible for identifying regional wetland subclasses, identification of reference wetlands, construction of assessment models, definition of reference standards, and calibration of assessment models.
Functional Assessment: The process by which the capacity of a wetland to perform a function is measured or estimated. The Hydrogeomorphic Approach measures capacity using an assessment model to determine a functional capacity index.
Functional Capacity: The rate or magnitude at which a wetland ecosystem performs a function. Functional capacity is dictated by characteristics of the wetland ecosystem and the surrounding landscape, and interaction between the two.
Functional Capacity Index (FCI): An index of the capacity of a wetland to perform a function relative to other wetlands within a regional wetland subclass in a reference domain. Functional capacity indices are by definition scaled from 0.0 to 1.0. An index of 1.0 indicates the wetland performs a function at the highest sustainable functional capacity, the level equivalent to a wetland under reference standard conditions in a reference domain. An index of 0.0 indicates the wetland does not perform the function at a measurable level, and will not recover the capacity to perform the function through natural processes.
Highest Sustainable Functional Capacity: The level of functional capacity achieved across the suite of functions by a wetland under reference standard conditions in a reference domain. This approach assumes that the highest sustainable functional capacity is achieved when a wetland ecosystem and the surrounding landscape are undisturbed.
Hydrogeomorphic Wetland Class: The highest level in the hydrogeomorphic wetland classification. There are seven basic hydrogeomorphic wetland classes including depressional, fringe--lacustrine and coastal, slope, riverine, and flat--mineral and organic.
Project Target: The level of functioning identified for a restoration or creation project. Conditions specified for the functioning are used to judge whether a project reaches the target and is developing toward site capacity.
Project Standards: Performance criteria and/or specifications used to guide the restoration or creation activities toward the project target. Project standards should include and specify reasonable contingency measures if the project target is not being achieved.
Red Flag Features: Features of a wetland or the surrounding landscape to which special recognition or protection is assigned on the basis of objective criteria. The recognition or protection may occur at a federal, state, regional, or local level, and may be official or
unofficial.
Reference: Standard for measuring, reckoning, or constructing.
Reference Domain: The geographic area from which reference wetlands are selected. A reference domain may or may not include the entire geographic area in which a regional wetland subclass occurs.
Reference Standard Wetlands: The sites within a reference wetland data set from which reference standards are developed. Among all reference wetlands, reference standard sites are judged by an interdisciplinary team to have the highest level of functioning.
Reference Standards: Conditions exhibited by a group of reference wetlands that correspond to the highest level of functioning (highest, sustainable level of functioning) across the suite of functions performed by the regional wetland subclass. The highest level of functional capacity is assigned an index score of 1.0 by definition.
Reference Wetlands: Wetland sites that encompass the variability of a regional wetland subclass in a reference domain. Reference wetlands are used to establish the range of conditions for construction and calibration of functional indices and establish reference standards.
Regional Wetland Subclass: Wetlands within a region that are similar based on hydrogeomorphic classification factors. There may be more than one regional wetland subclass identified within each hydrogeomorphic wetland class depending on the diversity of wetlands in a region, and assessment objectives.
Site Potential: The highest level of functioning possible, given local constraints of disturbance history, land use, or other factors. Site capacity may be equal to or less than levels of functioning established by reference standards for the reference domain, and it may be equal to or less than the functional capacity of a wetland ecosystem.
Wetland Functions: The normal activities or actions that occur in wetland ecosystems, or simply, the things that wetlands do. Wetland functions result directly from the characteristics of a wetland ecosystem and the surrounding landscape, and their interaction.

[FR Doc. 97-15959 Filed 6-19-97; 8:45 am]
BILLING CODE 3710-92-P