Kent, Donald M. “Definition, Classification, and U.S. Regulation” Applied Wetlands Science and Technology Editor Donald M. Kent Boca Raton: CRC Press LLC,2001 ©2001 CRC Press LLC CHAPTER 1 Definition, Classification, and U.S. Regulation Donald M. Kent CONTENTS Definition Classification Classification of Wetlands and Deepwater Habitats of the United States A Hydrogeomorphic Classification for Wetlands U.S. Regulation Regulating Agencies Army Corps of Engineers Environmental Protection Agency Fish and Wildlife Service National Resource Conservation Service National Marine Fisheries Service References DEFINITION Wetlands are defined directly or implicitly in a variety of ways. Several factors, including personal perspective, position in the landscape, and wetland diversity and function, contribute to the tractable nature of the definition. Each individual or group brings to the definition its own perspective based upon cumulative experience and personal needs (Figures 1 to 4). For example, the lay person asked to define wetlands may envision a deep-water marsh teeming with ©2001 CRC Press LLC ducks, or alternatively a dark swamp. To an engineer a wetland may be a place that will require a specialized construction design to accommodate poorly drained soils. The scientist likely has a functional perspective, defining a wetland as a place where anaerobic processes occur, and plants are adapted specially for living in saturated or inundated conditions. Finally, those charged with regulating wetland use are likely to have a structural perspective, defining wetlands by characteristic soil, hydrology, and plants so as to facilitate permit decision making. Defining wetlands is further complicated by their position in the landscape. Wetlands are transitional habitats in the sense that they are neither terrestrial nor aquatic, but exhibit characteristics of both. Their boundaries are part of a continuum of physical and functional characters, and may expand or contract over time depend- ing upon factors such as average annual precipitation, evapotranspiration, and mod- ifications to the watershed. The transitional nature of wetland characteristics and the shifting of wetland boundaries renders precise identification of wetland boundaries difficult if not impossible. The diversity of wetland types also contributes to the tractable nature of the definition. Wetlands include such familiar habitats as marsh and swamp, as well as less familiar seasonal wetlands such as vernal pools and intermittent streams. They may be tidal or nontidal, saline or fresh, lotic or lentic, permanent or imper- manent. Vegetation may consist of herbaceous or woody species, or there may be no vegetation. Figure 1 Salt marsh is an emergent, interdial estuarine wetland system characterized by persistent plant species such as cordgrass ( Spartina alterniflora ). Saltmarsh has a fringe geomorphic setting, and the water source and hydrodynamics are pre- dominantly surface or near surface bidirectional flows. ©2001 CRC Press LLC Wetlands also defy a unifying functional definition. Each wetland is unique with respect to its size, shape, hydrology, soils, vegetation, and its position in the land- scape. As such, wetlands exhibit a wide range of functional attributes, including provision of aquatic and wildlife habitat, retention of sediments and toxicants, flood Figure 2 This marsh is an emergent, palustrine wetland with a depressional setting. It is subject to vertical fluctuations in water level, and derives its water from precipitation and groundwater discharge. Figure 3 Palustrine wetlands may also be wooded as illustrated by this hardwood swamp. Swamps frequently have a riverine setting and unidirectional, surface or near- surface flows. ©2001 CRC Press LLC attenuation, nutrient metabolism, groundwater recharge, and production export. Individual wetlands may exhibit some of these attributes, all of these attributes, or in rare instances, none of these attributes. Moreover, individual wetlands of similar attributes are likely to provide functions to differing degrees. Despite the difficulty in singularly defining wetlands, several formal definitions have been proposed. The earliest definition was for managers and scientists, partic- ularly those concerned with waterfowl and wildlife (Shaw and Fredine, 1956). Largely a structural definition, it uses language understandable to the lay person. The term wetland … refers to lowlands covered with shallow and sometimes tempo- rary or intermittent waters. They are referred to by such names as marshes, swamps, bogs, wet meadows, potholes, sloughs, and river-overflow lands. Shallow lakes and ponds, usually with emergent vegetation as a conspicuous feature, are included in the definition, but the permanent waters of streams, reservoirs, and deep lakes are not included. Neither are water areas that are so temporary as to have little or no effect on the development of moist-soil vegetation. The definition established two parameters essential for a habitat to be a wetland: the presence of surface water and the development of moist-soil vegetation. At a workshop of the Canadian National Wetlands Working Group, 23 years later, a definition evolved that recognized a third parameter, hydric soils, and which noted the functional attributes of wetlands (Tarnocai, 1979). Furthermore, it expanded the previous definition of wetland to include not only those habitats with surface water but also those having saturated soils. Figure 4 This vernal pool in California is inundated or saturated for a short time in early spring. It occurs in a depressional setting and is dependent upon precipitation for water. ©2001 CRC Press LLC Wetland is defined as land having the water table at, near, or above the land surface or which is saturated for a long enough period to promote wetland or aquatic processes as indicated by hydric soils, hydrophilic vegetation, and various kinds of biological activity which are adapted to the wet environment. That same year, the U.S. Fish and Wildlife Service adopted a definition that also recognized wetland hydrology, hydric soils, and hydrophytic vegetation as defining parameters (Cowardin et al., 1979). Intended for wetland scientists, the definition is distinguished from the Canadian definition in that a wetland need not exhibit char- acteristics of all three parameters. Wetlands are lands transitional between terrestrial and aquatic systems where the water table is usually at or near the surface or the land is covered by shallow water. For purposes of this classification wetlands must have one or more of the following three attributes: (1) at least periodically, the land supports predominantly hydrophytes; (2) the substrate is predominantly undrained hydric soils; and (3) the substrate is nonsoil and is saturated with water or covered by shallow water at some time during the growing season each year. The three-parameter approach developed for scientists and managers is reflected in Section 404 of the Clean Water Act, forming the basis for regulatory decision making. The term “ wetlands ” means those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas. CLASSIFICATION Classification is the act or process of classifying; systematically arranging in groups or categories according to established criteria. For example, Linnaean tax- onomy is a binomial nomenclature providing for orderly classification of plants and animals according to their presumed natural relationships. Classification schemes may be hierarchical or nonhierarchical. If hierarchical, the classification scheme may be divisive or agglomerative, and monothetic or polythetic. Hierarchical, divisive, polythetic classifications are common and lend themselves to a wide range of scientific applications. Regardless of the scheme used, the effect of classification is to provide a common language. Many wetland classification schemes have been developed (e.g., Martin et al., 1953; Stewart and Kantrud, 1971; Golet and Larson, 1974). The classification system developed by Cowardin et al. (1979) and the classification system developed by Brinson (1993) have received wide acceptance by scientists, policymakers, and managers. These classifications can be applied across broad geographic areas and in large part encompass many other classification schemes. ©2001 CRC Press LLC Classification of Wetlands and Deepwater Habitats of the United States In 1974, the U.S. Fish and Wildlife Service directed its Office of Biological Services to design and conduct a national inventory of wetlands. Existing classifi- cation systems were considered too simplistic (Martin et al., 1953) or too geograph- ically limited (Stewart and Kantrud, 1971; Golet and Larson, 1974; Odum et al., 1974; Zoltai et al., 1975) to satisfy the requirements of a national inventory. Cow- ardin et al. (1979) developed a classification of wetlands and deepwater habitats of the United States to support the national inventory. The objectives of the classification were to describe ecological units with homogeneous natural attributes, to arrange these units in a system that would aid resource management decisions, to furnish units for inventory and mapping, and to provide uniformity in concepts and termi- nology throughout the United States. Their classification of wetlands and deepwater habitats of the United States is hierarchical, divisive, and polythetic (Table 1). Wetland and deepwater systems are made up of subsystems, subsystems of classes, and classes of subclasses. Domi- nance types (plants and animals) are attributed to subclasses. Water regime, water chemistry, and soil modifiers are applied to classes, subclasses, and dominance types. For example, according to the classification, a cordgrass ( Spartina sp.) saltmarsh would be estuarine (system), intertidal (subsystem), emergent (class), and persistent (subclass). Systems are a complex of wetlands and deepwater habitats that share hydrology, geomorphology, chemistry, and biology. The classification has five major systems: marine, estuarine, riverine, lacustrine, and palustrine. Subsystems are more specific categories of systems and provide hydrological information. Marine and estuarine systems encompass subtidal and intertidal subsystems. The riverine system includes a tidal subsystem, as well as lower perennial, upper perennial, and intermittent subsystems. Limnetic and littoral subsystems comprise the lacustrine system. The palustrine system is not divided into subsystems. The class describes the general appearance of the habitat. Classes are defined by either the dominant vegetation form or the physiography and composition of the substrate. Examples include rock bottom, aquatic bed, emergent wetland, and for- ested wetland. Cowardin et al. (1979) intended that the classes be discernible without extensive biological knowledge, and in many cases recognizable by remote sensing. Finer differences in vegetation form or substrate are recognized at the subclass level. For example, rock bottom is divided into bedrock and rubble, and emergent wetland is divided into persistent and nonpersistent. Dominance type is the most precise category and reflects the dominant plant species or dominant sedentary or sessile macroinvertebrate. Class, subclass, and dominance type levels of the classification are more fully described by modifiers. Water regime modifiers describe hydrological characteristics and require detailed knowledge of duration and timing of surface inundation. Salinity in all habitats, and pH in freshwater habitats, are water chemistry modifiers. Soil modifiers are mineral and organic. The classification also includes special modifiers to describe man-made wetlands, and wetlands modified by the activity of persons or beavers. ©2001 CRC Press LLC Table 1 A Classification of Wetlands and Deepwater Habitats of the United States (Cowardin et al., 1979) System Subsystem Class Marine Subtidal Rock bottom Unconsolidated bottom Aquatic bed Reef Intertidal Aquatic bed Reef Rocky shore Unconsolidated shore Estuarine Subtidal Rock bottom Unconsolidated bottom Aquatic bed Reef Intertidal Aquatic bed Reef Streambed Rocky shore Unconsolidated shore Emergent wetland Scrub–shrub wetland Forested wetland Riverine Tidal Rock bottom Unconsolidated bottom Aquatic bed Rocky shore Unconsolidated shore Emergent wetland Lower perennial Rock bottom Unconsolidated bottom Aquatic bed Rocky shore Unconsolidated shore Emergent wetland Upper Perennial Rock bottom Unconsolidated bottom Aquatic bed Rocky shore Unconsolidated shore Intermittent Streambed Lacustrine Limnetic Rock bottom Unconsolidated bottom Aquatic bed Littoral Rock bottom Unconsolidated bottom Aquatic bed Rocky shore Unconsolidated shore Emergent wetland Palustrine Rock bottom Unconsolidated bottom Aquatic bed Unconsolidated shore Moss–lichen wetland Emergent wetland Scrub–shrub wetland Forested wetland ©2001 CRC Press LLC Cowardin et al. (1979) designed the classification for use over a broad geographic area, and for use by individuals and organizations with varied interests and objec- tives. Information about the wetland or deepwater area to be classified is obtained directly from site inspections, or indirectly from maps, aerial photographs, and other sources. The type and extent of information necessarily determine the level to which the area is classified. Cowardin et al. (1979) intended the classification to be open- ended and incomplete below the class level. Users are expected to identify additional dominance types and add subclasses as necessary. A Hydrogeomorphic Classification for Wetlands A hydrogeomorphic classification for wetlands presented by Brinson (1993, 1995) emphasizes the abiotic characteristics of wetlands. The abiotic characteristics are intended to be indicators of wetland functions. Brinson (1993) suggests that a functionally based classification of wetlands is needed for two reasons. First, the concept of wetlands needs to be simplified to improve communication among researchers, managers, and the public, and this communication is best achieved by focusing on processes that are fundamental to sustained existence. Second, para- digms that clarify the relationship between ecosystem structure and function must be developed to support monitoring of ecosystem health. A hydrogeomorphic classification for wetlands was developed to support ongo- ing efforts at assessing the physical, chemical, and biological functions of wetlands subject to U.S. Army Corps of Engineers permit. It has its scientific origins in a coastal ecosystem classification system based upon biological, geological, chemical, and physical factors (Odum et al., 1974); a mangrove classification system relying on vegetation and on water source, quality, and flow (Lugo and Snedaker, 1974); and a study by Brown et al. (1979) that found that differences among freshwater forested wetlands are attributed to the amount of water flow. Kangas (1990), who developed a wetland classification system based upon energy flow and landscape properties, also influenced the classification. The classification is nonhierarchical and has three interdependent components: geomorphic setting, water source and its transport, and hydrodynamics (Table 2). Geomorphic setting is defined as the topographic location of the wetland within the surrounding landscape. The seven geomorphic settings tend to have distinct combi- nations of hydroperiod, dominant direction of water flow, and zonation of vegetation. An individual wetland may have characteristics of more than one geomorphic setting category. Also, a small wetland (e.g., less than or equal to 1 ha) may be difficult to assign to a geomorphic setting category if it is part of a larger wetland complex. Water sources include precipitation, groundwater discharge, and surface or near- surface flow. The latter include flooding from tides, overbank flow from stream channels, and interflow or overland flow from higher potentiometric surfaces. Pre- cipitation is, of course, a contributor to all wetlands and its relative importance is a function of the contribution of groundwater and surface water. The relative impor- tance of the three sources of water can be determined by construction of a water budget, or more quantitatively by interpreting a hydrograph of the wetland. Bogs ©2001 CRC Press LLC and pocosins are heavily influenced by precipitation, fens and seeps by groundwater discharge, and riverine and fringe wetlands by surface and near-surface flow. Hydrodynamics refers to the direction of flow and strength of water movement within the wetland. There are three qualitative categories of hydrodynamics: vertical fluctuations, unidirectional flows, and bidirectional flows. Astronomic tides, wind, or a combination of both generate the latter. The classification makes inferences about hydrodynamics based upon velocity of flow, rate of water table fluctuations, particle size distribution of bedload sediments, and the capacity to replace soil moisture deficits created by evapotranspiration. These correspond, respectively, to the depressional, riverine, and fringe geomorphic settings. Implementing the classification requires use of indicators of wetland ecological significance, profile development, and comparison to reference wetlands. Indicators are observed in the field, or derived from maps, photographs, water quality data, or other sources. Representative indicators of ecological significance include water characteristics such as suspended sediment and salinity, water color, pH, nutrient status, and soil or sediment characteristics (Table 3). Ecological significance, as determined from direct observation of wetland function or from indicators, is then used to develop a profile for the wetland. A profile may be either narrative or tabular, and is the end point of the classification. Brinson (1993) recommends that profile development be tied to the establishment of reference wetlands that would be used to facilitate assessment, training, and mitigation. The classification emphasizes the interpretation of wetland ecological signifi- cance based upon geomorphic setting, water source, and hydrodynamics, and illus- trates how fundamental knowledge about water flows and sources can reveal eco- logical functioning. It does not allow the user to take it to the field for the purpose of matching indicators with functions (Brinson, 1993). Also, the interpretation of ecological significance results in the description of wetland function without neces- sarily placing the wetland into a discrete category. Brinson (1993) expects that the Table 2 Hydrogeomorphic Classification for Wetlands (Brinson, 1993, 1995) Geomorphic setting Riverine Depressional Slope Mineral soil flats Organic soil flats Estuarine fringe Lacustrine fringe Water source Precipitation Groundwater discharge Surface or near-surface inflow Hydrodynamics Vertical fluctuations Unidirectional flows Bidirectional surface or near-surface flows [...]... economics, aesthetics, ©20 01 CRC Press LLC Table 4 Significant Federal Wetlands- Related Legislation Legislation Date Effect on Wetlands Section 10 , Rivers and Harbors Act 18 99 Migratory Bird Hunting and Conservation Stamp Act Federal Aid to Wildlife Restoration Act 19 34 19 37 Fish and Wildlife Act 19 56 U.S Fish and Wildlife Coordination Act 19 58 Land and Water Conservation Fund Act 19 65 National Wildlife... 92, 19 71 ©20 01 CRC Press LLC Tarnocai, C., Canadian wetland registry, in Proceedings of a Workshop on Canadian Wetlands Environment, Rubec, D D A and Pollett, F C., Eds., Canada Land Directorate, Ecological Land Classification Series, No 12 , 19 79, 9 United States General Accounting Office, Wetlands Overview: Federal and State Policies, Legislation and Programs, GAO/RCED-92–79FS, Washington, D.C., 19 91. .. Wetland Reserve Program 19 85 Emergency Wetlands Resources Act 19 86 Agricultural Credit Act 19 87 Everglades National Park Protection and Expansion Act North American Wetlands Conservation Act 19 89 Food, Agriculture, Conservation and Trade Act 19 90 Prohibits federal expenditure or assistance for development on coastal barriers ©20 01 CRC Press LLC 19 89 Discourages farming on wetlands Removes erodible crop land... Program Table 4 (continued) Significant Federal Wetlands- Related Legislation Legislation Date Effect on Wetlands Water Resources Development Act 19 90 Coastal Wetlands Planning, Protection and Restoration Act 19 90 Coastal Zone Management and Improvement Act 19 90 Requires federal agency development of action plan to achieve no-net loss Restoration of coastal wetlands and funds North American Waterfowl Management... General Technical Report WO -1 2 , U.S Department of Agriculture, Washington, D.C., 19 79, 17 Cowardin, L M., Carter, V., Golet, F C., and LaRoe, E T., Classification of Wetlands and Deepwater Habitats of the United States, U.S Department of the Interior, Fish and Wildlife Service Biological Services Program FWS/OBS-79/ 31, 19 79 Golet, F C and Larson, J S., Classification of Freshwater Wetlands in the Glaciated... Service, Resource Publication 11 6, 19 74 Kangas, P C., An energy theory of landscape for classifying wetlands, in Lugo, A E., Brinson, M M., and Brown, S., Eds., Forested Wetlands, Elsevier, Amsterdam, 19 90, 15 Lugo, A E and Snedaker, S C., The ecology of mangroves, Ann Rev Ecol Syst., 5, 39, 19 74 Martin, A C., Hotchkiss, N., Uhler, F M., and Bourn, W S., Classification of Wetlands of the United States,... enter into a cost-share restoration agreement to restore and protect wetlands The landowner continues to control access to the land, and may lease the land for undeveloped recreational activities (e.g., hunting, fishing) Another program that removes land from use is authorized by The Water Bank Act of 19 70 (16 U.S.C 13 01) The Water Bank Program provides funds to purchase 10 -year easements on wetlands and... Insurance Act 19 66 19 68 National Environmental Policy Act 19 69 Water Bank Act Endangered Species Act 19 70 19 73 Resource Conservation and Recovery Act 19 76 Section 402, Federal Water Pollution Control Act Section 404, Federal Water Pollution Control Act Coastal Barrier Resources Act 19 77 Requires permits from U.S Army Corps of Engineers for dredge and fill activities in navigible waterways and wetlands Proceeds... region of the United States Two other programs having a significant affect on the preservation of wetlands are the Migratory Bird Hunting and Conservation Stamp Act of 19 34 (16 U.S.C 718 ) and the Coastal Barrier Resources Act of 19 82 (16 U.S.C 35 01) The Stamp Act uses proceeds from duck stamps to preserve wetlands and adjacent uplands important to waterfowl through purchase or perpetual easement The... Hydrogeomorphic Classification for Wetlands, Technical Report WRP-DE-4, U.S Army Engineer Waterways Experiment Station, Vicksburg, MS, 19 93 Brinson, M M., The HGM approach explained, Natl Wet Newsl., November/December, 7, 19 95 Brown, S., Brinson, M M., and Lugo, A E., Structure and function of riparian wetlands, in Strategies for the Protection and Management of Floodplain Wetlands and Other Riparian Ecosystems, . al., 19 53) or too geograph- ically limited (Stewart and Kantrud, 19 71; Golet and Larson, 19 74; Odum et al., 19 74; Zoltai et al., 19 75) to satisfy the requirements of a national inventory. Cow- ardin. Bank Act of 19 70 (16 U.S.C. 13 01) . The Water Bank Program provides funds to purchase 10 -year easements on wetlands and adjacent areas for the purpose of preserving, restoring, and improving the wetlands. . Classification, and U.S. Regulation” Applied Wetlands Science and Technology Editor Donald M. Kent Boca Raton: CRC Press LLC,20 01 ©20 01 CRC Press LLC CHAPTER 1 Definition, Classification, and U.S.