DRAFT REVISED FEDERAL MANUAL FOR IDENTIFYING AND DELINEATING VEGETATED WETLANDS APRIL 26, 1991 cr> j HEADQUARTERS LIBRARY 1 ENVIRONMENTAL PROTECTION AGENCY WASHINGTON. D.C. 20460 ------- TABLE OF CONTENTS Part I. INTRODUCTION Purpose Organization of the Manual Use of the Manual Background Federal Wetland Definitions Section 404 of the Clean Water Act Food Security Act of 1985 Fish and Wildlife Service's Wetland Classification System Page 1 1 1 1 2 5 5 6 Part II. Relationship of Wetlands Identified by this Manual to "Waters of the United States" Summary of Federal Definitions MANDATORY TECHNICAL CRITERIA FOR VEGETATED WETLAND IDENTIFICATION WETLAND HYDROLOGY CRITERION 10 Wetland Hydrology Background 13 Measuring Wetland Hydrology 14 Historical Recorded Hydrologic Data 15 Aerial Photographs 15 Field Observations 16 Direct Evidence of Water 16 other Signs of Wetland Hydrology 16 HYDROPHYTIC VEGETATION CRITERION 18 Hydrophytic Vegetation Background 19 National List of Wetland Plant Species 20 Dominant Vegetation 21 HYDRIC SOIL CRITERION 22 Hydric Soil Background 23 National and State Hydric Soils Lists 23 County Hydric Soil Map Unit Lists 24 Soil Surveys 24 Use of County Hydric Soils Map Units Lists and Soil Surveys 25 General Characteristics of Hydric Soils 25 Organic Soils 26 Hydric Mineral Soils 27 Soil Related Evidence of Significant Saturation 28 Difficult-to-Identify Wetlands 31 Forested Wetlands 31 Streamside/Riparian Wetlands 3l Wet Meadows/Prairie Wetlands 32 ------- Pocosins Playas Prairie Potholes Vernal Pools Part III. STANDARD METHODS FOR IDENTIFICATION AND DELINEATION OF WETLANDS Selection of a Method Description of Methods Offsite Preliminary Determinations Onsite Determinations Disturbed Area Wetland Determinations Appendices Appendix 1. Appendix 2. Appendix 3. Appendix 4. Appendix 5. Appendix 6. Appendix 7. Appendix 8. Offsite Preliminary Determination Method Routine Onsite Determination Method Intermediate-level Onsite Determination Method Comprehensive Onsite Determination Method Descriptions of Difficult-to-Identify Wetlands Difficult-to-Identify Hydric Soils Procedures for Difficult-to-Identify Wetlands Disturbed Area Procedures 32 32 33 33 34 34 38 38 38 41 43 43 46 52 59 74 82 86 89 ------- FART I. INTRODUCTION Purpose The purposes of this manual are: (1) to provide mandatory technical criteria for the identification and delineation of wetlands, (2) to provide recommended methods for vegetated wetlands identification and upper boundary delineation, and (3) to provide sources of information to aid in their identification. The document can be used to identify jurisdictional wetlands subject to Section 404 of the Clean Water Act and to the "Swampbuster" provision of the Food Security Act of 1985, as amended, or to identify vegetated wetlands in general for the National Wetlands Inventory and other purposes. Wetland jurisdictional determinations for regulatory purposes are based on criteria in addition to technical criteria, so consult the appropriate regulatory agency for its interpretation. The tern "wetland" as used throughout this manual refers to vegetated wetlands. This includes wetlands with natural vegetation and wetlands where natural vegetation has been temporarily disturbed. This manual provides a single, consistent approach for identifying and delineating these wetlands from a multi-agency Federal perspective. Organization of the Manual This manual is divided into three major parts: Part I - Introduction; Part II - Mandatory Technical Criteria for Vegetated Wetland Identification; and Part III - Methods for Identification and Delineation of Vegetated Wetlands. References, a glossary of technical terms, and appendices are also included. Use of the Manual This manual should be used for the identification and delineation of vegetated wetlands in the United States. Emphasis for delineation is on the upper boundary of wetlands (i.e., wetland-upland boundary') and not on the lower boundary between wetlands and other aquatic habitats. The technical criteria for wetland identification presented in Part II are mandatory, while the methods presented in Part III are recommended approaches. Alternative methods are offered to provide users with a selection of methods that range from office determinations to detailed field determinations. If the user departs from these methods, the reasons for doing so should be documented. If there are any inconsistencies between Parts I, II, and III, the guidance provided in Part II has preeminence over guidance provided in the other parts. ------- Background At the Federal level, four agencies are principally involved with wetland identification and delineation: Army Corps of Engineers (CE), Environmental Protection Agency (EPA), Fish and Wildlife Service (FWS), and soil Conservation Service (SCS). The CE and EPA are responsible for making jurisdictional determinations of wetlands regulated under Section 404 of the Clean Water Act (formerly known as the Federal Water Pollution Control Act, 33 U.S.C. 1344). The CE also makes jurisdictional determinations under Section 10 of the Rivers and Harbors Act of 1899 (33 U.S.C. 403). Under Section 404, the Secretary of the Army, acting through the Chief of Engineers, is authorized to issue permits for the discharge of dredged or fill material into the waters of the United States, including wetlands. EPA has an important role in developing the Section 404(b)(l) Guidelines and defining the geographic extent of waters of the Unites States, including wetlands. The CE also issues permits for filling, dredging, and other construction in certain wetlands under Section 10. Under authority of the Fish and Wildlife Coordination Act, the FWS and the National Marine Fisheries Service review applications for these Federal permits and provide comments to the CE on the environmental impacts of proposed work. In addition, the FWS is conducting an inventory of the Nation's wetlands and is producing a series of National Wetlands Inventory maps for the entire country. While the SCS has been involved in wetland identification since 1956, it has recently become more deeply involved in wetland determinations through the "Swampbuster" provision of the Food Security Act of 1985, and the 1990 amendments. Prior to the adoption of the "Federal Manual for Identifying and Delineating Jurisdictional Wetlands" by the four agencies in 1989, each agency had its own procedures for identifying and delineating wetlands. The CE and EPA developed technical manuals for identifying and delineating wetlands subject to Section 404 (Environmental Laboratory 1987 and Sipple 1988, respectively), yet neither manual was a nationally-implemented standard even within the agencies. Consequently, wetland identification and delineation remained inconsistent. The SCS developed procedures for identifying wetlands for compliance with "Swampbuster" which were adopted by the agency for national use in 1987 (7 CFR Part 12). While it has no formal method for delineating wetland boundaries, the FWS has established guidelines for identifying wetlands in the form of its official wetland classification system report (Cowardin, et al. 1979). These varied agency approaches and lack of standardized methods resulted in inconsistent determinations of wetland boundaries for the same type of area. This created confusion and identified the need for a single, consistent approach for wetland determinations and boundary delineations. ------- In early 1988, the CE and EPA resumed previous discussions on the possibilities of merging their manuals into a single document and establishing it as a national standard within the agencies, since both manuals were produced in support of Section 404 of the Clean Water Act. The FWS and SCS were invited to participate, thereby creating the Federal Interagency Committee for Wetland Delineation (Committee) with each of the four agencies (CE, EPA, FWS, and SCS) represented. The four agencies reached agreement on the technical criteria for identifying and delineating wetlands and merged their methods into a single wetland delineation manual, which was published on January 10, 1989 as the "Federal Manual for Identifying and Delineating Jurisdictional Wetlands". This established a national standard for wetland identification and delineation, and terminated previous locally implemented approaches that were not, in some cases, scientifically based nor consistent. Further, adoption of the manual in 1989 resulted in some changes in the scope of regulatory jurisdiction in some agency field offices. During the following two years, the 1989 manual was used by the agencies for wetland delineation, chiefly for identifying and delineating wetlands subject to federal regulations under the Clean Water Act. Unfortunately, during this time many misconceptions about the intent of the 1989 manual, misapplication of the 1989 manual (e.g., classifying any area mapped as hydric soil as wetland without considering other criteria), and other factors created an obvious need to review the 1989 manual and revise it accordingly. From the outset, the Committee recognized that additional clarification and/or changes might be required. Accordingly, in May 1990, the Committee initiated an evaluation of the 1989 manual, which consisted of several steps: 1. Formal field testing was conducted by the Environmental Protection Agency to evaluate the sampling protocols of the 1989 manual (Sipple and DaVia 1990} ; 2. Reviews by agency field staff using the 1989 manual; 3. To afford the public the opportunity to comment on the technical aspects of the 1989 manual, public meetings were held in Baton Rouge, Louisiana, Sacramento, California, St. Paul, Minnesota, and Baltimore, Maryland; and 4. Written comments on the technical aspects of the 1989 manual were also accepted subsequent to the meetings to give the public ample opportunity to express any concerns. More than 500 letters were received and reviewed. ------- The technical comments were reviewed by the Committee and considered for incorporation into a revised manual. The Agencies concluded that while the manual represented a substantial improvement over pre-existing approaches, several key issues needed to be re-examined and clarified. Some of the key technical issues needing re-examination were: (1) the wetland hydrology criterion, (2) the use of hydric soil for delineating the wetland boundary, (3) the assumption that facultative vegetation indicated wetland hydrology, and (4) the open-ended nature of the determination process which created opportunities for misuse. The wetland hydrology criterion in the 1989 manual included a series of requirements related to specific soil types (soil drainage classes). Looking for water tables at various depths depending on soil drainage class was confusing, especially since properties associated with soil drainage classes are not standardized across the country. The National Technical Committee for Hydric Soils (NTCHS) criteria for defining hydric soils were adopted in the 1989 manual. The hydric soil criterion included wetland hydrology requirements to identify those soils wet enough to be hydric. In adopting the NTCHS hydric soil criteria, the 1989 manual retained the hydrology requirements under its hydric soil criterion and also in effect, repeated them as the wetland hydrology criterion. This clearly gave the impression of a less than three criteria approach to wetland identification. Perhaps the issue that engendered the most concern over potential misuse of the 1989 manual involved the use of hydric soils for wetland identification and delineation. Since the 1989 manual included wetland hydrology requirements within the hydric soil criterion, and the delineation methods relied on hydric soil properties to delineate the wetland boundary, some users got the impression that the.1989 manual was not based on three mandatory criteria, but rather based solely on one criterion - the hydric soil criterion (since it, in fact, embodied the wetland hydrology criterion). This, by itself, was not a significant problem, since hydrology was still considered. Some users then erroneously translated this to mean that any area mapped as a hydric soil series was a wetland. However, it was the clear intent of the agencies that specific soil properties derived directly from wetland hydrology (e.g., significant soil saturation) would be used to separate those members of hydric soil series that were associated with wetlands from those that were not. Hydric soil napping units include significant acreage of phases of these soils that were never wetland or no longer meet the wetland hydrology requirements of the hydric soil criterion (i.e., dry phases and drained phases, respectively) as well as inclusions of nonhydric soils. By considering any mapped hydric soil area as wetland, millions ------- of former wetlands (now effectively drained) could be misidentified as wetland. This grossly exaggerated the extent of "jurisdictional wetlands" present in the United States. While the presence of certain plants were required to separate vegetated wetlands from nonvegetated wetlands, they were not used to help identify the upper boundaries, although they can be very useful indicators in certain cases where hydrology has been altered or where soil properties themselves are difficult to interpret. Consequently, by ignoring plant composition on the upper end of the wetland/upland gradient and by erroneously using napped boundaries of hydric soil units to delineate wetland boundaries, errors in judgment were possible. The 1989 manual specified three mandatory criteria, but did not require the use of various indicators to verify these criteria, although the interrelationships were presented. This allowed individuals to develop their own indicators or ignore strong indicators in determining whether a particular criterion was met. Clearly, the criteria needed to be intricately linked to a limited set of field indicators to prevent their misuse. A series of meetings of the Committee were held during the period of October 1990 through April 1991. Major revisions to the 1989 manual were made to correct the technically-based shortcomings addressed above, reduce misinterpretations and the possibility of erroneous wetland determinations, and better explain the manual's usage. Federal Wetland Definitions Several definitions have been formulated at the Federal level to define "wetland" for various laws, regulations, and programs. These definitions are cited below with reference to their guiding document along with a few comments on their key elements. Section 404 of the Clean Water Act The following definition of wetland is the regulatory definition used by the EPA and CE for administering the Section 404 permit program: Those areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, «md 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 (EPA, 40 CFR 230.3, December 24, 1980; and CE, 33 CFR 328.3, November 13, 1986). This definition emphasizes hydrology, vegetation, and saturated soils. The Section 404 regulations also deal with other "waters ------- of the United States" such as open .water areas, mud flats, coral reefs, riffle and pool complexes, vegetated shallows, and other aquatic habitats. Both EPA and CE regulations (cited above) implementing this definition were subject to formal rulemaking public notice and comment procedures in accordance with the Administrative Procedures Act (5 USC 553). Food Security Act of 1985 (as amended) The following wetland definition is used by the SCS for identifying wetlands on agricultural land in assessing farmer eligibility for U.S. Department of Agriculture program benefits under the "Swampbuster" provision of this Act: Wetlands are defined as areas that have a predominance of hydric soils and that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and under normal circumstances do support, a prevalence of hydrophytic vegetation typically adapted for life in saturated soil conditions, except lands in Alaska identified as having a high potential for agricultural development and a predominance of permafrost soils.* (National Food Security Act Manual, 1988 and revised editions) *Special Note: The Emergency Wetlands Resources Act of 1986 also contains this definition, but without the exception for Alaska. This definition specifies hydrology, hydrophytic vegetation, and hydric soils. Any area that meets the hydric soil criteria (defined by the National Technical Committee for Hydric Soils) is considered to have a predominance of hydric soils. The definition also makes a geographic exclusion for Alaska, so that wetlands in Alaska with a high potential for agricultural development and a predominance of permafrost soils are exempt from the requirements of the Food Security Act. Fish and Wildlife Service's Wetland Classification System The FWS in cooperation with other Federal agencies, state agencies, and private organizations and individuals developed a wetland definition for conducting an inventory of the Nation's wetlands. This definition was published in the FWS's publication "Classification of Wetlands and Deepwater Habitats of the United States0 (Cowardin, et al. 1979): 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 soil, and (3) the substrate is nonsoil and is ------- saturated with water or covered by.shallow water at some time during the growing season of each year. This definition includes both vegetated and nonvegetated wetlands, recognizing that some types of wetlands lack vegetation (e.g., mud flats, sand flats, rocky shores, gravel beaches, and sand bars). The classification system also defines "deepwater habitats" as "permanently flooded lands lying below the deepwater boundary of wetlands." Deepwater habitats include estuarine and marine aquatic beds (similar to "vegetated shallows" of Section 404}, although aquatic beds in shallow fresh water are considered wetlands. Open waters below extreme low water at spring tides in salt and brackish tidal areas and usually below 6.6 feet in inland areas and freshwater tidal areas are also included in deepwater habitats. Relationship of Wetlands Identified by this Manual to "Haters of the United States" This manual is used to identify and delineate vegetated wetlands. Figure 1 presents a generalized landscape continuum from upland to open water (deepwater habitat) showing the relationship of the various Federal wetland definitions. Vegetated wetlands as used herein means areas that, under normal circumstances, usually have hydrophytic vegetation, hydric soil, and wetland hydrology. Further, this manual applies to areas that are vegetated by erect, self-supporting vegetation (e.g., vegetation extending above the water's surface in aquatic areas or free-standing on soil). Vegetated wetlands are a subset of areas regulated as "Waters of the United States" under Section 404 of the Clean Water Act, and one of the areas regulated as "special aquatic sites" under the Section 404(b)(l) Guidelines promulgated by the Environmental Protection Agency. Other "special aquatic sites" include mudflats, vegetated shallows, coral reefs, riffle and pool complexes, and sanctuaries and refuges. Open water areas are also part of the "Waters of the United States." Vegetated wetlands are also a subset of those areas designated as wetlands under the FWS's "Classification of Wetlands and Deepwater Habitats of the United States." The FWS definition of wetland is used for National Wetlands Inventory and is nonregulatory in nature. The only differences between wetlands identified by FWS and this manual are those aquatic areas 6.6 feet or less in depth that do not contain emergent vegetation, or are unvegetateoT. Such areas are identified as wetlands under the FWS system, but not under the manual. However, there are few if any areas covered by the FWS classification system that are not covered under Section 404. For vegetated wetlands, the FWS classification system and this manual are essentially identical. Ninety-four percent of all FWS-classified wetlands in the ------- coterminous United states are vegetated. The emphasis of this manual is on the boundary between wetland and upland, since that is the area most often in question and where determinations and delineations become most difficult. However, wetland determinations in lower wetter areas are generally easy to make and seldom in question from a regulatory standpoint since both wetland and open water are regulated areas. Generally, as one moves up slope, it becomes increasingly more difficult to determine what areas are wetlands. This manual recognizes this fact and requires less rigorous investigation in obvious wetland situations than in areas which may be questionable. In either situation, however, documentation supporting a delineation is required. This manual does not change the existing definitions of wetlands used for Section 404 of the Clean Water Act and the Swampbuster provision of the 1985 Food Security Act, as amended, or the FWS wetland definition. The former two definitions are specific to vegetated wetlands or wetlands that are vegetated under normal circumstances. These are the wetlands to which the manual applies. This manual provides for the consistent identification and delineation of these wetlands in the field. Because this manual was developed to resolve differences in identifying wetlands under these definitions, it is limited to vegetated wetlands and does not address nonvegetated wetlands. Wetland determinations made through the use of this manual for the purposes of determining Federal wetland jurisdiction at a site are subject to modification in accordance with legal and policy considerations of the applicable regulatory program. For example, Section 404 regulatory jurisdiction in wetlands is limited to areas that are waters of the United States because they have a connection with interstate or foreign commerce. Another example is the application of Federal wetland jurisdiction on cropland which is subject to agency policy-based interpretations of such matters as the relative permanence of the cropping disturbance and its effect on hydrophytic vegetation and/or wetland hydrology. Such matters generally are not addressed in this manual; rather, the appropriate agency policy should be consulted in conjunction with the manual for wetland determinations in such areas. Summary of Federal Definitions The CE, EPA, and SCS wetland definitions include only areas that are vegetated under normal circumstances, while the FWS definition encompasses both vegetated and nonvegetated areas. Except for the FWS inclusion of nonvegetated areas and aquatic beds in shallow water as wetlands and the exemption for Alaska in the SCS definition, all four wetland definitions are conceptually the same; they all include three basic elements - hydrology, vegetation, and soils - for identifying wetlands. » 8 ------- PART II. MANDATORY TECHNICAL CRITERIA FOR VEGETATED WETLANDS IDENTIFICATION Wetland hydrology is the driving force of wetlands, vegetated wetlands occur in shallow water, on permanently saturated soils, or in areas subject to periodic inundation or saturation where anaerobic conditions usually develop due to excess water. Certain hydrologic conditions called "wetland hydrology" therefore drive the formation of wetlands and continue to. maintain them. Permanent or periodic wetness is the fundamental factor that makes wetlands different from uplands (nonwetlands). Although wetland hydrology is the dominant force creating wetlands, long-term records for hydrology typically are not available for identifying the presence of wetland? or for delineating their upper boundaries. Consequently other indicators sometimes must be used to determine whether an area meets the wetland criteria. It has been long recognized that various plants and their adaptations, certain plant communities,. specific soil properties, and particular soil types (e.g., peats, mucks, and gleyed soils) can be used to help identify wetlands. In addition, there are a number of hydrologic indicators that can be used to help identify wetlands. Existing wetland definitions recognize that wetlands are driven by wetland hydrology (permanent or periodic inundation and/or soil saturation) and that characteristic plants (hydrophytic vegetation) and soils (hydric soils) are identifiable components of vegetated wetlands. This manual uses these three components as criteria for vegetated wetland identification. Field staff should examine sites for indicators of hydrophytic vegetation, hydric soils, and wetland hydrology and document the presence or absence of indicators to the extent practicable. At sites where wetlands are obvious due to the overwhelming evidence provided by one indicator (e.g., large stands of undisturbed salt marsh), documentation of the other indicators, while necessary, need not be as intensive as in areas where wetlands are not so obvious. There are, however, many other cases where, as one moves toward the drier portion of the moisture gradient, rigorous examination and documentation of soil, vegetation, and hydrology characteristics is necessary. The fact that such wetlands are difficult to identify has no bearing on their status as wetlands. Under natural, undisturbed conditions, vegetated wetlands generally possess three characteristics: (1) hydrophytic vegetation, (2) hydric soils, and (3) wetland hydrology. These characteristics and their technical criteria for identification purposes are described in the following sections. The three technical criteria and their verifying characteristics are % 9 ------- mandatory. For an area to be identified as a wetland, all three criteria must be met by positive identification of the presence of one or more of the indicators described below for each criterion, with two noted exceptions: wetlands in disturbed conditions such that indicators of one or more of the criteria are absent,* and wetlands that are difficult to identify because natural fluctuations in hydrology or climate or other site- specific or unusual conditions prohibit their identification based on the standard criteria and indicators. The procedures to be used for identifying and delineating wetlands in areas that potentially fall within each of these categories of exceptions are included as an Appendix to this manual. Representative examples of difficult-to-identify wetlands are also discussed in this manual. Included with these examples are situations (e.g., pit and mound topography) encountered in the field that complicate the wetland delineation process. The three mandatory technical criteria are presented below. Background information for each criterion is also provided. WETLAND HYDROLOGY CRITERION An area has wetland hydrology when it is: 1. Inundated and/or saturated at the surface by surface water or ground water for more than 14 consecutive days during the growing season in most years, or 2. Periodically flooded by tidal water in most years. Areas meeting this criterion also are usually inundated or saturated for variable periods during the non-growing season. The term "inundated and/or saturated at the surface1* means the soil is inundated or wet enough at the surface to the extent that water reaches the surface in an unlined borehole or can be squeezed or shaken from the soil at the surface. The growing season is the interval between 3 weeks before the average date of the last killing frost in the Spring to 3 weeks after the average date of the first killing frost in the Fall, with exceptions for areas experiencing freezing temperatures throughout the year (e.g., montane, tundra and boreal areas) that nevertheless support hydrophytic vegetation. The term "in most years" means that the condition would occur more than 50 years out of 100 years and, therefore, represents the prevailing long-term hydrologic condition. While the above criterion must be met, many times field staff will not be present to do wetland determinations at the right time of year or for long enough to directly observe more than two weeks of inundation and/or saturation. Accordingly, field personnel need to use indicators of wetland hydrology as a basis for professional judgment on whether the hydrology criterion is 10 ------- met. An area meets the wetland hydrology criterion above by direct measurement of inundation and/or soil saturation or tidal flooding or as documented by one or more of the following indicators (also see note on page 13): 1. A minimum of 3 years of hydrologic records (e.g., groundwater well observations following the protocol on page 99, or tide or stream gauge records) collected during years of normal rainfall (amount and monthly distribution) and correlated with long-term hydrologic records for the specific geographical area that demonstrates the area meets the wetland hydrology criterion; or 2. Examination of aerial photography (preferably early spring or wet part of the growing season) for a minimum of 5 years reveals evidence of inundation and/or saturation in most years (e.g., 3 of 5 years or 6 of 10 years) and correlated with long-term hydrologic records for the specific geographical areas demonstrate that the area meets the wetland hydrology criterion; or 3. One or more primary hydrologic indicators below, which, when considered with evidence of frequency and duration of rainfall or other hydrologic conditions, provide evidence sufficient to establish that more than 14 consecutive days of inundation and/or saturation at the surface during the growing season occurs, are materially present: a. Surface water inundation; or b. Observed free water at the surface in an unlined borehole; or c. water can be squeezed or shaken from a soil sample taken at the soil surface; or d. Oxidized stains along the channels of living roots (Oxidized rhizospheres); or e. Sulfidic material (distinct hydrogen sulfide, rotten egg odor) within 12 inches of the soil surface; or f. Water-stained leaves, trunks or stems that are grayish or blackish in appearance as a result of being underwater for significant periods; or g. Specific plant morphological adaptation/responses 11 ------- to prolonged inundation or saturation: pneumatophores, prop roots, hypertrophied lenticels, arenchymous tissues, and floating stems and leaves of floating-leaved plants growing in the area (may be observed lying flat on the soil), and buttressed trunks or steins. Always consider the frequency and duration of these primary indicators (or of the wetness that created them), and whether significant hydrologic modification (e.g., drainage) has effectively removed wetland hydrology from the site. Inundation for seven consecutive days during the growing season generally results in saturation at the surface for a total of more than 14 consecutive days. However, certain inundated wetlands (e.g., some prairie potholes, playa lakes and vernal pools) exhibit anaerobic conditions at the surface but may not have 7 days of saturation at the surface following 7 days of inundation. These and other exceptions are addressed on page 31 below as difficult-to-identify wetlands. 4. If none of the indicators in items 1, 2, or 3 above is present, one or more of the following secondary hydrologic indicators should be used in conjunction with collateral information (e.g., maps) that supports a wetland hydrology determination: a. Silt marks (waterborne silt deposits) that indicate inundation; or b. Drift lines; or c. Surface-scoured areas; or d. Other common plant morphological adaptations/responses to hydrology: shallow root systems and adventitious roots. These secondary indicators may only be used in conjunction with other collateral information that indicates wetland hydrology (e.g., regional indicators of saturation, hydrologic gauge data, county soil surveys, National Wetlands Inventory maps, aerial photographs, or reliable persons with local knowledge of inundation and/or saturated conditions). This type of information may also can be used to support determinations based on the primary indicators listed above. NOTE: IN ADDITION, CERTAIN SEASONALLY-SATURATED WETLANDS MAY LACK THE ABOVE HYDROLOGIC INDICATORS DURING A PORTION OF THE 12 ------- GROWING SEASON DUE TO SEASONAL DRYNESS OR OTHER NORMAL HYDROLOG1C FLUCTUATIONS. SUCH AREAS ARE LISTED AS DIFFICULT-TO-IDENTIFY WETLANDS (See Page 31). UNLESS SPECIFICALLY ADDRESSED IN THE DIFFICULT-TO-IDENTIFY OR DISTURBED AREAS SECTIONS OF THE HANUAL, AREAS WITHOUT ANY OF THE ABOVE HYDROLOGIC INDICATORS ARE NONWETLAND. IN AREAS OF SUSPECTED SIGNIFICANT HYDROLOGIC MODIFICATION, FOLLOW THE DISTURBED AREA PROCEDURES TO DETERMINE IF WETLAND HYDROLOGY STILL EXISTS PAGE 41. Wetland Hydrology Background The driving force creating wetlands is "wetland hydrology," that is, permanent or periodic inundation, or soil saturation for a significant period (two weeks or more) during the growing season. Many wetlands are found along rivers, lakes, and estuaries where flooding is likely to occur, while other wetlands form in isolated depressions surrounded by upland where surface water collects. Still others develop on slopes of varying steepness, in surface water drainageways, or where ground water discharges to the land surface in spring or seepage areas. Thus, landscape position provides much insight into whether an area is likely to be subjected to wetland hydrology. Permanent or periodic inundation, or soil saturation at the surface, at least seasonally, are the driving forces behind wetland formation. The presence of water in the soil for two weeks or more during the growing season typically creates anaerobic conditions, which affect the types of plants that can grow and the types of soils that develop. These conditions hold true for most wetlands, especially those at the upper end of the soil moisture gradient. Anaerobiosis does not necessarily occur in all wetlands and those where it may not occur include vegetated sand bars, seepage areas, springs, and the upper edges of salt marshes. These exceptions are addressed below as difficult-to-identify wetlands. Wetlands have at least a seasonal or periodic abundance of water. For example, this water may come from direct precipitation, overbank flooding, surface water runoff due to precipitation or snow melt, ground water discharge, tidal flooding, irrigation, or other human-induced activities. The frequency and duration of inundation and soil saturation vary widely from permanent flooding or saturation to irregular flooding or saturation. Of the three technical criteria for wetland identification, wetland hydrology is often the least exact and most difficult to establish in the field, due largely to annual, seasonal, and daily fluctuations. Numerous factors influence the wetness of an area, including precipitation, stratigraphy, topography, soil permeability, and plant cover. The frequency and duration of inundation or soil saturation are important in separating wetlands from nonwetlands. Areas of lower elevation in a floodplain or marsh usually have longer duration of inundation and saturation and often more 13 ------- frequent periods of these conditions than most areas at higher levels. Floodplain configuration may significantly affect the duration of inundation by facilitating rapid runoff or by causing poor drainage. Soil permeability related to the texture of the soil also influences the duration of inundation or soil saturation. For example, clayey soils absorb water more slowly than sandy or loamy soils, and therefore have slower permeability and remain saturated much longer. Type and amount of plant cover affect both the degree of inundation and the duration of saturated soil conditions. Excess water drains more slowly in areas of abundant plant cover, thereby increasing duration of inundation or soil saturation. On the other hand, transpiration rates are higher in areas of abundant plant cover, which may reduce the duration of soil saturation. To determine whether the wetland hydrology criterion is met, one should consider recorded data, aerial photographs, and observed field conditions that provide direct or indirect evidence of inundation or soil saturation. Prolonged saturation often leaves evidence of such wetness in the soil (e.g., sulfur odor) and these properties are useful for verifying wetland hydrology provided the area's hydrology has not been significantly modified on-site or upstream in the watershed. If the hydrology has been significantly disturbed, particular care must be taken in assessing the wetland hydrology criterion; refer to disturbed area procedures (p. 41) to determine whether wetland hydrology still exists. Measuring Wetland Hydrology In certain instances, especially disturbed situations, it may be necessary to determine an area's hydrology by actively collecting on-site hydrologic data from direct measurements or observations. The duration and frequency of inundation by flooding may be established by evaluating long-term stream or tide gauge data or by examining aerial photos covering at least a 5-year period and comparing results with the wetland hydrology criterion. Saturation at the surface may be determined by making observations in an unlined borehole and establishing whether or not the soil is saturated at the surface for more than 14 days during the growing season. A procedure for this is presented in the Disturbed Areas section of the manual (p. 41). In general, if soil saturation is observed at the surface for more than 14 days during the growing season wetland hydrology probably exists. Interpretation of the above observations, however, must always be done with consideration of recent rainfall conditions (e.g., within the past few weeks) as well as the long-term rainfall patterns (e.g., abnormally wet or dry periods) preceding and 14 ------- during the time the hydrologic data were recorded. Historical Recorded Hydrologic Data Historical recorded hydrologic data usually provide both short- and long-term information on the frequency and duration of flooding, but little or no information on soil saturation periods. Historical recorded data include stream gauge data, lake gauge data, tide gauge data, flood predictions, and . historical flood records. Use of these data is commonly limited to areas adjacent to streams and other similar areas. Recorded data may be available from the following sources: (1) CE district offices (data for major waterbodies and for site-specific areas from planning and design documents), (2) U.S. Geological Survey (stream and tidal gauge data), (3) National Oceanic and Atmospheric Administration (tidal gauge data), (4) State, county and local agencies (flood data), (5) SCS state offices (small watershed projects and water table study data), and (6) private developers or landowners (site-specific hydrologic data, which nay include water table or groundwater well data). Aerial Photographs Aerial photographs may provide direct evidence of inundation or soil saturation at the surface in an area. Inundation (flooding or ponding) is best observed during the early spring in temperate and boreal regions when snow and ice are gone and leaves of deciduous trees and shrubs are not yet fully developed. This allows detection of wet soil conditions that would be obscured by i:he tree or shrub canopy at full leaf-out. For marshes, this reason of photography is also desirable, except in regions characterized by distinct dry and rainy seasons, such as southern Florida and California. Wetland hydrology would be best observed during the wet season in these latter areas. It is most desirable to examine several consecutive years of oarly spring or wet season aerial photographs to document evidence of wetland inundation or soil saturation. In this way, the effects of abnormally dry or wet springs, for example, may be ninimized. in interpreting aerial photographs, it is important to taow the antecedent weather conditions. This will help eliminate potential misinterpretations caused by abnormally wet or dry periods. Contact the U..S. Weather Service for historical weather records or the U.S. Geological Survey for hydrologic records. Aerial photographs for agricultural regions of the country are often available at county offices of the Agricultural Stabilization and Conservation Service. 15 ------- Field Observations Direct Evidence of Water At certain tines of the year in wetlands, and in certain types of wetlands at most tines, wetland hydrology is quite evident, since surface water or saturated soils (e.g., soggy or wetter underfoot) may be observed. The most obvious and revealing hydrologic indicator nay be sinply observing the areal extent of inundation. However, both seasonal conditions and recent weather conditions must be considered when observing an area because they can affect the presence of surface water on wetland and nonwetland sites. In many cases, soils saturated at the surface are obvious, since the ground surface is soggy or mucky under- foot. To observe free water at the surface it may be necessary to dig a hole and observe the level at which water stands in the hole after sufficient time has been allowed for water to drain into the hole. In some cases, the upper level at which water is flowing into the hole can be observed by examining the walls of the hole. This level may represent the depth to the water table. In some heavy clay soils, however, water may not rapidly accumulate in the hole even when the soil is saturated, when attempting to observe free water in a bore hole, adequate time should be allowed for water in the hole to reach equilibrium with the water table. Soil saturation at the surface may be detected by a "squeeze test" or "shake test" which involve taking a surface soil sample and squeezing or shaking the sample. If water can be extracted, the soil is considered saturated at the surface. When evaluating soil saturation, both the season of the year and the preceding weather conditions must be considered, since excess water may not be present during parts of the growing season in some wetlands due to high evaporation and plant transpiration rates which effectively lower the water table. At such times, other indicators of wetland hydrology may be present. Other Signs of Wetland Hydrology It is not necessary to observe inundation or saturation at the time of field inspection to identify wetland hydrology so long as indicators are sufficient to demonstrate to field personnel that the wetland hydrology criterion on page 10 is met. Other signs of wetland hydrology may be observed, e.g., oxidized rhizospheres (root channels) and water-stained leaves or stems. Some plants are able to survive saturated soil conditions (i.e., a reducing environment) because they can transport oxygen to their root zone. Iron oxide concretions (orangish or reddish 16 ------- brown in color) may form along the channels of living roots and rhizomes creating oxidized rhizospheres that provide evidence of soil saturation (anaerobic conditions) for a significant period during the growing season. Ephemeral or temporary oxidized rhizospheres may develop after abnormally heavy rainfall periods. Consequently, oxidized rhizospheres are most meaningful when observed with other wetland indicators especially in undrained soils displaying diagnostic hydric soil properties. Forested wetlands that are inundated earlier in the year will frequently have trees and shrubs with water-stained trunks or stems if flooded for long periods, or water-stained leaves in depressions on the forest floor. The stems are usually black- colored to the normal high water mark. The leaves are generally grayish or blackish in appearance, darkened from being underwater for significant periods. Other signs that may reflect wetland hydrology include water marks, drift lines, water-borne deposits, surface-scoured areas, wetland drainage patterns, and certain plant morphological adaptations. (1) Water marks are found most commonly on woody vegetation or fixed objects (e.g., bridge pillars, buildings, and fences) but may also be observed on other vegetation. They often occur as dark stains on bark or other fixed objects. (2) Drift lines are typically found adjacent to streams or other sources of water flow in wetlands and often occur in tidal marshes. Evidence consists of deposition of debris in a line on the wetland surface or debris entangled in aboveground vegetation or other fixed objects. Debris usually consists of remnants of vegetation (branches, stems, and leaves), litter, and other water-borne materials often deposited more-or less parallel to the direction of water flow. Drift linen provide an indication of the minimum portion of the area inundated during a flooding event; the maximum level of inundation is generally at a higher elevation that indicated by a drift line. The drift lines in tidal wetlands are often referred to as "wrack lines." (3) Water-borne deposits of mineral or organic matter may be observed on plants and other objects after inundation. This evidence may remain for a considerable period before it is removed by precipitation or subsequent inundation. Silt deposition on vegetation and other objects provides an indication of the minimum inundation level. When the deposits are primarily organic (e.g., fine organic material and algae), the detritus may become encrusted on or slightly above the soil surface after dewatering occurs. Sediment deposits (e.g., sandy material) along streams provide 17 ------- <\f evidence of recent overbank flooding. (4) Surface scouring occurs along floodplains where overbank flooding erodes sediments (e.g., at the bases of trees). The absence of leaf litter from the soil surface is also sometimes an indication of surface scouring. Forested wetlands that contain standing waters for relatively long duration will occasionally have areas of bare or essentially bare soil, sometimes associated with local depressions. (5) Many plants growing in wetlands have developed morphological features in response to inundation or soil saturation. Examples include pneumatophores (e.g., cypress knees), prop roots, floating stems and leaves, hypertrophied lenticels (oversized stem pore), aerenchyma (air-filled) tissue in roots and stems, buttressed tree trunks, multiple trunks, adventitious roots, shallow root systems, polymorphic leaves, inflated leaves, stems or roots. Pneumatophores, prop roots, floating stems and leaves, hypertrophied lenticels, aerenchyma tissue, and buttresssed tree trunks develop virtually only in wetland or aquatic environments and therefore are listed as primary hydrologic indicators in the wetland hydrology criterion. When these features are observed in young plants, they provide good evidence that wetland hydrology exists. Multiple trunks, adventitious roots, shallow root systems, polymorphic leaves, inflated leaves, stems or roots are commonly found in many wetland plants, yet not exclusive to them, and therefore are listed as secondary hydrologic indicators in the wetland hydrology criterion and indicate wetlands only when accompanied by other collateral information that indicates wetland hydrology. HYDROPHYTIC VEGETATION CRITERION An area meets the hydrophytic vegetation criterion when, under normal circumstances: (1) more than 50 percent of the dominant species from all strata are obligate wetland (OBL), facultative wetland (FACW), and/or facultative (FAC) species, or (2) a frequency analysis of all species within the community yields a prevalence index value of less than 3.0 (where OBL = 1.0, FACW - 2.0, FAC » 3.0, FACU - 4.0, and UPL - 5.0). NOTE: WETLAND TYPES THAT MAY HAVE VEGETATION THAT DOES NOT MEET THIS CRITERION ARE LISTED AS DIFFICULT-TO-IDENTIFY WETLANDS (SEE PAGE 31). AREAS WHERE THE VEGETATION HAS BEEN REMOVED WILL GENERALLY MEET THE HYDROPHYTIC VEGETATION CRITERIA IF THEY ARE CAPABLE OF SUPPORTING SUCH VEGETATION. (SEE DISTURBED AREAS 18 ------- SECTION, PAGE 41) For each stratum (e.g.,, tree, shrub, and herb) in the plant community, dominant species are determined by ranking all species in descending order of dominance (e.g., areal cover or basal area) and cumulatively totaling species until they exceed 50 percent of the total dominance measure (e.g., total areal coverage or total basal area for a sample plot). All species that contribute to exceeding the 50 percent level are considered dominant species. Any additional species comprising 20 percent or more of the total dominance measure for the stratum is also considered a dominant species. All dominants, regardless of stratum, are treated equally in determining the presence of hydrophytic vegetation. A valid stratum for identifying dominants in the plant community must have at least 5 percent areal cover within the observation area (e.g., plot). Hydrophytic Vegetation Background The term "hydrophytic vegetation" describes plants that live in conditions of excess wetness. For purposes of this manual, hydrophytes are defined, as macrophytic plant life growing in water or on submerged substrates, or in soil or on a substrate that is at least periodically anaerobic (deficient in oxygen) as a result of excessive water content. All plants growing in wetlands have adapted in one way or another to life in permanently or periodically inundated or saturated soils. Some plants have developed structural or morphological adaptations to inundation or saturation, while others have broad ecological tolerances (Tiner, 1991). Some of these features are used as indicators of wetland hydrology in this manual (see hydrology criterion page 10), since they are a response to inundation and/or soil saturation. Probably all plants growing in wetlands possess physiological mechanisms to cope with periodic anaerobic soil conditions or 1-ife in water. Because they are not observable in the field, physiological and reproductive adaptations are not included in this manual. Persons making wetland determinations should be able to identify at least the dominant wetland plants in each stratum (layer of vegetation) of a plant community. Plant identification requires the use of field guides or more technical taxonomic manuals (see Appendix for sample list). When necessary, seek help in identifying difficult species. Once a plant is identified to genus and species, consult the appropriate Federal list of plants that occur in wetlands to determine the "wetland indicator status" of the plant (see explanation below). This information will be used to help determine whether the hydrophytic vegetation criterion is met. One should also become familiar with the technical literature on wetlands, especially for one's geographic region. Sources of ^ 19 ------- available literature include: taxonomic plant manuals and field guides; scientific journals dealing with botany, ecology, and wetlands in particular; technical government reports on wetlands; proceedings of wetland workshops, conferences, and symposia; and the FWS'S national- wetland plant database, which contains habitat information on about 7,000 plant species. Appendix presents examples of the first four sources of information. In addition, the FWS's National Wetlands Inventory (NWI) maps provide information on locations of hydrophytic plant communities that can be studied in the field to improve one's knowledge of such communities in particular regions. If all wetland plant species grew only in wetlands, plants alone could be used to identify and delineate wetlands. However, of the nearly 7,000 vascular plant species which have been found growing in U.S. wetlands (Reed 1988), only about 27 percent are "obligate wetland" species that nearly always occur in wetlands under natural conditions. This means that the majority of plant species growing in wetlands also grow in nonwetlands to varying degrees. These plants may or may not be hydrophytes depending on where they are growing. This variability in habitat occurrence causes certain difficulties in identifying wetlands from a purely botanical standpoint in many cases. This is a major reason for evaluating soils and hydrology when identifying wetlands. National List of Wetland Plant Species The FWS in cooperation with CE, EPA, and SCS has published the "National List of Plant Species That Occur in Wetlands" from a review of the scientific literature and review by selected wetland experts and botanists (Reed 1988). The list separates vascular plants into four basic groups, commonly called "wetland indicator status," based on a plant species' frequency of occurrence in wetlands: (1) obligate wetland plants (OBL) that occur almost always'(estimated probability >99%) in wetlands under natural conditions; (2) facultative wetland plants (FACW) that usually occur in wetlands (estimated probability 67-99%), but occasionally are found in nonwetlands; (3) facultative plants (FAC) that are nearly equally likely to occur in wetlands or nonwetlands (estimated probability 34-66%); and (4) facultative upland plants (FACU) that usually occur in nonwetlands (estimated probability 67-99%), but occasionally are found in wetlands (estimated probability 1-33%). If a species occurs almost always (estimated probability >99%) in nonwetlands under natural conditions, it is considered an obligate upland plant (UPL). These latter plants do not usually appear on the wetland plant list; they are listed only in some regions of the country. If a species is not on the list, it is presumed to be an obligate upland plant, yet be advised that the list intentionally does not include nonvascular plant species (e.g., algae and mosses) or epiphytic plants. These omitted plants should not be considered in determining whether the hydrophytic vegetation criterion is 20 ------- met, unless one has particular knowledge of their frequency of occurrence in wetlands. Also be sure to check for synonyms in plant scientific names, since the nomenclature used in the list varies for some species from that used in regional taxonomic manuals or commonly used plant identification field guides. The "National List of Plant Species That Occur in Wetlands" has been subdivided into regional and state lists. There is a formal procedure to petition the interagency plant review committee for making additions, deletions, and changes in indicator status. Since the lists are periodically updated, the U.S. Fish and Wildlife Service should be consulted to be sure that the most current version is being used for wetland determinations.' The appropriate plant list for a specific geographic region should be used when making a wetland determination and evaluating whether the hydrophytic vegetation criterion is satisfied. (Note; The "National List of Plant Species that Occur in Wetlands" uses a plus (+) sign or a minus (-) sign to signify a higher or lower portion of a particular wetland indicator frequency for the three facultative-type indicators; for purposes of identifying hydrophytic vegetation according to this manual, however, FACW+, FACW-, FAC+, and FAC- are included as FACW and FAC, respectively, in the hydrophytic vegetation criterion.) Dominant Vegetation Dominance as used in this manual refers strictly to the spatial extent of a species that is directly discernable or measurable in the field. When identifying dominant vegetation within a given plant community, one should consider dominance within each valid stratum. All dominants are treated equally in characterizing the plant community to determine whether the hydrophvtie vegetation criterion is met. For each stratum (e.g., tree, shrub, and herb} in the plant community, dominant species are determined by ranking all species.in descending order of dominance (e.g., areal cover or basal area) and cumulatively totaling species until they exceed 50 percent of the total dominance measure (e.g., total areal coverage or total basal area for a sample plot). All species that contribute to exceeding the 50 percent level are considered dominant species, along with any additional species comprising 20 percent or more of the total dominance measure for the stratum. Vegetative strata for which dominants should be determined may include: (1) tree (>5.0 inches diameter at breast height (dbh) and 20 feet or taller); (2) sapling (0.4 to <5.0 inches dbh and 20 feet or taller); (3) shrub (usually 3 to 20 feet tall including multi-stemmed, bushy shrubs and small trees below 20 feet tall); (4) woody vine; and (5) herb (herbaceous plants including graminoids, forbs, ferns, fern allies, herbaceous vines, and tree seedlings). Bryophytes (mosses, horned liverworts, and true liverworts) should be sampled as a separate * 21 ------- stratum in certain wetlands, including shrub bogs, moss-lichen wetlands, and wooded swamps where bryophytes are abundant and represent an important component of the community, in most other wetlands, bryophytes should be included within the herb stratum due to their scarcity. In order to be counted as a valid stratum, a stratum must have at least 5 percent areal cover for the area under evaluation, e.g., 5-foot radius plot for herbs and 30-foot radius plot for woody plants. This minimum does not apply to woody vines; use professional judgment to determine whether they are abundant enough to count as a stratum. Always document the omission of any such stratum from the final evaluation regarding the hydrophytic vegetation criterion. There are many ways to estimate or quantify dominance measures. Dominant species for each stratum can be determined by estimating one or more of the following, as appropriate: (1) relative basal area (trees); (2) areal cover (all strata); or (3) stem density (all strata). Direct measurement of tree diameters at breast height provides data for calculating basal area for determining dominant tree species. Alternatively, one may wish to perform a frequency analysis of all species within a given plant community. These are accepted methods for evaluating plant communities. Part III of this manual provides recommended approaches for sampling or analyzing the plant community. HYDRIC BOIL CRITERION An area has hydric soil when it has either: 1. Soils listed by series in "Hydric Soils of the United States" (1987 and amendments), or 2. Organic soils (Histosols, except Folists), or 3. Mineral soils classifying as Sulfaquents, Kydraquents, or Histic subgroups of Aquic suborders, or 4. Other soils that meet the National Technical Committee for Hydric Soils' criteria for hydric soil. An area meets the hydric soil criterion when it has one or more of the following: 1. Where soil survey maps are available, the subject area is within: a. a hydric soil map unit identified on the county list of hydric soil map units that is verified by landscape position and soil morphology against the series description of the hydric soil, or » 22 ------- b. a soil map unit with hydric soil inclusions identified on the county list of hydric soil map units, and the landscape position of the inclusion and the soil morphology for the identified soil series as a hydric soil inclusion are verified, or, if no series is designated, then either: 1} the soil, classified to the series level, is on the national list of hydric soils, or 2) the soil, classified according to "Soil Taxonomy", is a Histosol (except Folists), Sulfaquent, Hydraquent, or Histic Subgroup of Aquic Suborders, or 3} regional indicators of significant soil saturation are materially present; or 2. Where soil maps are not available, and the landscape position is likely to contain hydric soil (e.g., floodplain, depression, or seepage slope), subject area has either: a. the soil, classified to the series level, is on the national list of hydric soils, or b. the soil, classified according to "Soil Taxonomy", is a Histosol (except Folists), Sulfaguent, Hydraquent, or Histic Subgroup of Aquic Suborders, or c. regional indicators of significant soil saturation are materially present. Hydric Soil Background Wetlands typically possess hydric soils, but not all areas mapped as a hydric soil series are wetlands (e.g., dry phases that were never wetlands and drained phases that represent former wetlands). Hydric soils are defined as soils that are saturated, 1:1coded, or ponded long enough during the growing season to develop anaerobic conditions in the upper part (U.S.D.A. Soil Conservation Service 1987). These soils usually support hydrophytic vegetation under natural (unaltered) conditions. National and State Hydric Soils Lists The SCS in cooperation with the National Technical Committee for Hydric Soils (NTCHS) has prepared a list of the Nation's hydric s.oils (U.S.D.A. Soil Conservation Service 1987). State lists have also been prepared for statewide use. The national and state lists identify those soil series that typically meet the NTCHS 1 23 ------- hydric soil criteria according to available soil interpretation records in SCS's soils database. These lists are periodically updated, so make sure the list being used is the current one. The list, while extensive, does not include all series that nay have hydric members; these soils may be determined as hydric when they have evidence of wetland hydrology and hydrophytic vegetation. The lists facilitate use of SCS county soil surveys for identifying potential wetlands. One roust be careful, however, in using the soil survey, because a soil map unit of a nonhydric soil may have inclusions of hydric soil that were not delineated on the map or vice versa. Also, some map units (e.g., alluvial land, swamp, tidal marsh, muck and peat) may be hydric soil areas, but are not on the hydric soils lists because they were not given a series name at the time of mapping. These soils meet the NTCHS criteria for hydric soils. County Hydric Soil Map Unit Lists Because of the limitations of the national and state hydric soil lists, the SCS prepared lists of hydric soil map units for each county in the United States. These lists may be obtained from local SCS district offices and are the preferred lists to be used when using soil survey maps. The hydric soil map unit lists identify all map units that are either named by a hydric soil or that have a potential of having hydric soil inclusions. The lists provide the map unit symbol, the name of the hydric soil part or parts of the map unit, information on the hydric soil composition of the map unit, and probable landscape position of hydric soils in the map unit delineation. The county lists also include map units named by miscellaneous land types or higher levels in "Soil Taxonomy" that meet NTCHS hydric soil criteria. Soil Surveys The SCS publishes soil surveys for areas where soil mapping is completed. Soil surveys that meet standards of the National Cooperative Soil Survey (NCSS) are used to identify areas of hydric soils. These soil surveys may be published (completed) or unpublished (on file at local SCS field offices). Published soil surveys of an area may be obtained from the local SCS field office or the Agricultural Extension Service office. Unpublished maps may be obtained from the local SCS district office. The NCSS maps contain four kinds of map units: (1) consociations, (2) complexes, (3) associations, and (4) undifferentiated groups. (Note: Inclusions of unnamed soils may be contained within any map unit; the inclusions are listed in the description of the soil map unit in the soil survey report.) Consociations are soil map units named for a single kind of soil (taxon) or miscellaneous area. Seventy-five percent or more of the area is composed of the taxon for which the map unit is named (and similar taxa). When named by a hydric soil, the map unit is 24 ------- considered a hydric soil nap unit for wetland determinations. However, snail areas within these nap units generally too snail to be napped separately (sone areas are identified by "wet spot" symbols) nay not be hydric and should be excluded in delineating wetlands. Complexes and associations are soil nap units named by two or nore kinds of soils (taxa) or miscellaneous areas. If all taxa for which these map units are naned are hydric, the soil map unit nay be considered a hydric soil map unit for wetland determinations. If only part of the map unit is made up of hydric soils, only those portions of the map unit that are hydric are considered in wetland determinations. Undifferentiated groups are soil nap units naned by two or nore kinds of soils or miscellaneous areas. The soils in these map units do not always occur together in the sane nap unit but are included together because sone common feature such as steepness or flooding determines use and management. These map units are distinguished from the others in that "and" is used as a conjunction in the nane, while dashes are used for conplexes and associations. If all conponents are hydric, the nap unit nay be considered a hydric soil nap unit. If one or nore of the soils for which the unit is naned are nonhydric, each area must be examined for the presence of hydric soils. Use of County Hydric Soils Map Unit Lists and Soil Surveys The county hydric soils nap unit list and soil surveys should be used to help determine if the hydric soil criterion is met in a given area. When making a wetland determination, one should first locate the area of concern on a soil survey map and identify the soil nap units for the area. The county list of hydric soil nap units should be consulted to determine whether the soil nap units are hydric or potentially hydric. If hydric soil nap units or map units with hydric soil inclusions are noted, then one should exanine the soil in the field and compare its morphology with the corresponding hydric soil description in the soil survey report. If the soil's characteristics natch those described for hydric soil, then the hydric soil criterion is net, unless the soil has been effectively drained. If soils have been significantly disturbed, either mechanically or hydrologically, refer to the disturbed areas section on page 41. In the absence of site- specific information, hydric soil's also may be recognized by certain soil properties caused by wetland hydrology conditions that make soil neet the NTCHS criteria for hydric soils. General Characteristics of Hydric Soils Due to their wetness during the growing season, hydric soils usually develop certain morphological properties that can be readily observed in the field. Anaerobic soil conditions usually * 25 ------- occur due to excessive wetness and they typically lower the soil redox potential causing a chemical reduction of some soil components, mainly iron oxides and manganese oxides. This reduction affects solubility, movement, and aggregation of these oxides which is reflected in the soil color and other physical characteristics that are usually indicative of hydric soils. Soils are separated into two major types on the basis of material composition: organic soil and mineral soil. In general, soils with at least 16 inches of organic material in the upper part of the soil profile and soils with organic material resting on bedrock are considered organic soils (Histosols). Soils largely composed of sand, silt, and/or clay are mineral soils. For technical definitions, see "Soil Taxonomy", U.S.D.A. Soil Survey staff 1975. Organic Soils Accumulation of organic matter in most organic soils results from anaerobic soil conditions associated with long periods of submergence or soil saturation during the growing season. These saturated conditions impede aerobic decomposition (oxidation) of the bulk organic materials such as leaves, stems, and roots, and encourage their accumulation over time as peat or muck. Consequently, most organic soils are characterized as very pporly drained soils. Organic soils typically form in waterlogged depressions, and peat or muck deposits may range from about 1.5 feet to more than 30 feet deep. Organic soils also develop in low-lying areas along coastal waters where tidal flooding is frequent. Hydric organic soils are subdivided into three groups based on the presence of identifiable plant material: (1) muck (Saprists) in which two-thirds or more of the material is decomposed and less than one-third of the plant fibers are identifiable; (2) peat (Fibrists) in which less than one-third of the material is decomposed and more than two-thirds of the plant fibers are still identifiable; and (3) mucky peat or peaty muck (Hemists) in which the ratio of decomposed to identifiable plant matter is more nearly even (U.S.D.A. Soil Survey Staff 1975). A fourth group of organic soils (Folists) exists in tropical and boreal mountainous areas where precipitation exceeds the evapotranspiration rate, but these soils are never saturated for more than a few days after heavy rains and thus do not develop under hydric conditions. All organic soils, with the exception of the Folists, are hydric soils. Hydric organic soils can be easily recognized as black-colored muck to dark brown-colored peat. Distinguishing mucks from peats based on the relative degree of decomposition is fairly simple. In mucks (Saprists), almost all of the plant remains have been decomposed beyond recognition. When rubbed, mucks feel greasy and » 26 ------- leave hands dirty, in contrast, the plant remains in peats (Fibrists) show little decomposition and the original constituent plants can be recognized fairly easily. When the organic matter is rubbed between the fingers, most plants fibers will remain identifiable, leaving hands relatively clean. Between the extremes of mucks and peats, organic soils with partially decomposed plant fibers (Hemists) can be recognized. In peaty mucks up to two-thirds of the plant fibers can be destroyed by rubbing the materials between the fingers, while in mucky peats up to two-thirds of the plant remains are still recognizable after rubbing. Hydric Mineral Soils When less organic material accumulates in soil, the soil is classified as mineral soil. Some mineral soils may have thick organic surface layers (histic epipedons) due to heavy seasonal rainfall or a high water table, yet these soils are still composed largely of mineral matter (Ponnamperuma 1972). Mineral soils that are covered with moving (flooded) or standing (ponded) water for significant periods or are saturated for extended periods during the growing season meet the NTCHS criteria for hydric soils and are classified as hydric mineral soils. Soil saturation may result from low-lying topographic position, groundwater seepage, or the presence of a slowly permeable layer (e.g., clay, confining layer, confining bedrock, or hardpan). The duration and depth of soil saturation are essential criteria for identifying hydric soils and wetlands. Soil morphological features are commonly used to indicate long-term soil moisture regimes (Bouma 1983). Table lists some of the more commonly observed morphological properties associated with hydric mineral soils having a Typic Subgroup and Aquic Suborder. A thick dark surface, layer, grayish subsurface and subsoil colors, the presence of orange or reddish brown (iron) and/or dark reddish brown or black (manganese) mottles or concretions near the surface, and the wet condition of the soil may help identify the hydric character of many mineral soils. The grayish subsurface and subsoil colors and thick, dark surface layers are the best indicators of current wetness, since the yellow- or orange-colored mottles are very insoluble and once formed may remain indefinitely as relict mottles of former wetness (Diers and Anderson 1984). A, histic epipedon (organic surface layer) is evidence of a soil meeting the NTCHS criteria. It is an 8 to 16 inch organic layer it or near the surface of a hydric mineral soil that is saturated with water for 30 consecutive days or more in roost years. It contains a minimum of 20 percent organic matter when no clay is present or a minimum of 30 percent organic matter when clay content is 60 percent or greater. Soils with histic epipedons are 27 ------- inundated or saturated for sufficient periods to greatly retard aerobic decomposition of organic natter/ and are considered hydric soils. In general, a histic epipedon is a thin surface layer of peat or muck if the soil has not been plowed (U.S.D.A. Soil Survey Staff -1975). Histic epipedons are typically designated as O-horizons (Oa, Oe, or Oi surface layers, and in some cases the terms "mucky11 or "peaty" are used as modifiers to the mineral soil texture term, e.g., mucky loam. Soil-related Evidence of Significant Saturation Identification of some wetlands and delineation of the upper boundary in many wetlands is not readily accomplished without a detailed examination of the underlying soil. Colors in the soil are strongly influenced by the frequency and duration of soil saturation which causes reducing conditions. A gleyed layer and a low chroma matrix with high chroma mottles, near the surface are common indicators of hydric soils throughout the county. Other soil markers of significant soil saturation vary regionally. These signs include thick organic surface layers (> 8 inches), gleying, and certain types of mottling. If significant drainage or groundwater alteration has taken place, then it is necessary to determine whether the area in question is effectively drained and is now nonwetland or is only partly drained and remains wetland despite some hydrologic modification. Guidance for determining whether an area is effectively drained is presented in the section on disturbed areas (p. 41). Soils saturated for prolonged periods during the growing season in most years are usually gleyed in the saturated zone. Gleyed layers are predominantly gray in color and occasionally greenish or bluish gray. In gleyed soils, the distinctive colors result from a process known as gleization. Prolonged saturation of mineral soil converts iron from its oxidized (ferric) form to its reduced (ferrous) state. These reduced compounds may be completely removed from the soil, resulting in gleying (Veneman, £t al. 1976). Mineral soils that are always saturated are typically uniformly gleyed throughout the saturated area. Soils gleyed to the surface layer are evidence of wetland hydrology and anaerobic soil conditions. These soils often show evidence of oxidizing conditions only along root channels. Some nonsaturated soils have gray layers (E-horizons) immediately below the surface layer that are gray for reasons other than saturation, such as leaching due to organic acids (see Spodosols page 83). Mineral soils that are alternately saturated and oxidized (aerated) during the year are usually mottled in the part of the soil that is seasonally wet. Mottles are spots or blotches of different colors or shades of colors interspersed with the dominant (matrix) color. The abundance, size, and color of the mottles usually reflect the hydrology - the duration of the saturation period, and indicate whether or not the soil is 28 ------- saturated for long periods. Mineral soils that are predominantly grayish with common or many, distinct or prominent brown or yellow mottles are usually saturated for long periods during the growing season and are hydric soils. Soils that are predominantly brown or yellow with gray mottles are saturated for shorter periods and may be hydric depending on the depth to the gray mottles and the color of the overlying layer. Mineral soils that are never saturated are usually bright-colored and are not mottled; they are nonhydric soils (Tiner and Veneman 1987). Realize, however, that in some hydric soils, mottles may not be visible due to masking by organic matter (Parker, et al. 1984). It is important to note that the gleization and mottle formation processes are strongly influenced by the activity of certain soil microorganisms. These microorganisms reduce iron when the soil * ivironment is anaerobic, that is, when virtually no free oxygen is present, and when the soil contains organic matter. If the soil conditions are such that free oxygen is present, organic matter is absent, or temperatures are too low (below 41 degrees Fahrenheit) to sustain microbial activity, gleization will not proceed and mottles will not form, even though the soil may be saturated for prolonged periods of time (Diers and Anderson 1984). Soil colors as discussed above often reveal much about a soil's historical wetness over the long term. Scientists and others examining the soil can determine the approximate soil color by comparing the soil sample with a Munsell soil color chart. The standardized Munsell soil colors are identified by three components: hue, value, and chroma. The hue is related to one of the main spectral colors: red, yellow, green, blue, or purple, or various mixtures of these principal colors. The value refers to the degree of lightness, while the chroma notation indicates the color strength or purity. In the Munsell soil color book, each individual hue has its own page (Figure ), each of which is further subdivided into units for value (on the vertical axis) and chroma (horizontal axis). Although theoretically each soil zolor represents a unique combination of hues, values, and shromas, the number of combinations common in the soil environment usually is limited. Because of this situation and the fact that accurate reproduction of each soil color is expensive, the Munsell soil color book contains a limited number of combinations of hues, values, and chromas. The color of the soil matrix or a mottle is determined by comparing a soil sample with the individual color chips in the soil color book. The appropriate Munsell color name can be read from the facing page in the "Munsell Soil Color Charts" (Kollmorgen Corporation 1975). Chromas of 2 or less are considered low chromas and are often diagnostic of hydric soils. Low chroma colors include black, various shades of gray, and the darker shades of brown and red. Gleying (bluish, greenish, or grayish colors) in or immediately 29 ------- below th* A-horizon is an indication of a markedly reduced hydric soil and an area that should meet wetland hydrology in the absence of significant hydrologic modification. Gleying can occur in both mottled and unaottled soils. Gleyed soil conditions can be determined by using the gley page of the "Munsell soil Color Charts" (Kollmorgen Corporation 1975). NOTE: GLEYED CONDITIONS NORMALLY EXTEND THROUGHOUT SATURATED SOILS. BEWARE OF SOILS WITH GRAY SUBSOILS DUE TO PARENT MATERIALS, SOILS WITH GRAY E-HORIZONS OR ALBIC HORIZONS DUE TO LEACHING AND NOT TO SATURATION; THESE LATTER SOILS CAN OFTEN BE RECOGNIZED BY BRIGHT-COLORED LAYERS BELOW THE E-HORIZON. SEE DISCUSSION ON DIFFICULT-TO-IDENTIFY WETLANDS SECTION Page 31. Mineral soils that are saturated for substantial periods of the growing season, but are unsaturated for some time, commonly develop mottles. Soils that have brightly colored mottles and a low chroma matrix are indicative of a fluctuating water table. The following color features in the horizon immediately below the A-horizon (or E-horizon, albic horizon) provide evidence of soil saturation sufficient to be hydric soils and should also meet the wetland hydrology criterion: (1) Matrix chroma of 2 or less in mottled soils, or (2) Matrix chroma of 1 or less in unmottled soils. NOTE: MOLLISOLS HAVE VALUE REQUIREMENTS OF 4 OR MORE AS WELL AS CHROMA REQUIREMENTS FOR AQUIC SUBORDERS; SEE DIFFICULT-TO-IDENTIFY HYDRIC SOILS FOR OTHER EXCEPTIONS. The chroma requirements above are for soils in a moistened condition. Colors noted for dry (unmoistened) soils should be clearly stated as such. The colors of the topsoil (A-horizon) are often not indicative of the hydrologic situation because cultivation and soil enrichment affect the original soil color. Hence, the soil colors below the A-horizon (and E-horizon, if present) usually must be examined. NOTE: BEWARE OF HYDRIC SOILS THAT HAVE COLORS OTHER THAN THOSE DESCRIBED ABOVE; SEE DIFFICULT-TO-IDENTIFY WETLANDS BELOW. During the oxidation-reduction process, the iron and manganese in solution in saturated soils are sometimes precipitated as oxides into concretions or soft masses upon exposure to air as the soil dries. Concretions are local concentrations of chemical compounds (e.g., iron oxide) in the form of a grain or nodule of varying size, shape, hardness, and color (Buckman and Brady 1969). Manganese concretions are usually black or dark brown, while iron concretions are usually yellow, orange or reddish brown. In wetlands, these concretions are also usually accompanied by soil colors as described above. 30 ------- DIFPICULT-TO-IDENTIFY WETLANDS All wetlands have wetland hydrology, hydric soil, and plants adapted to those conditions. However, there are exceptions where evidence of all three mandatory criteria is not readily observable, especially in the drier season of the year or during droughts. A procedure for identifying these difficult-to- identify wetlands is in Appendix 7. Before using the difficult- to-identify procedures, the assumption that an area may be a difficult-to-identify wetland must be based on strong well documented evidence, such as: the area is a wetland type that is listed in this manual as a difficult-to-identify wetland, the area is in a landscape position that is highly likely to support wetlands (e.g., significant depression or drainageway, or adjacency or proximity to a verified wetland or other waterbody), the area has vegetation that is known to be found in wetlands in the local area, or the area is underlain by a soil that is known to support wetlands in the local area. Wetland types that are difficult to identify are listed below and in Appendix 5. In some of the below-listed wetlands, such as playas, prairie potholes, vernal pools, and pocosins it may be difficult to identify more than one of the criteria during dry seasons of the year or droughts even though such wetlands would meet the criteria if visited at the optimal time of year for their delineation. Difficult-to-identify wetlands include the following categories: Forested Wetlands Some (but not all) forested wetlands may be difficult-to- identify. They are found in many parts of the country and meet the wetland hydrology criterion by inundation and/or saturation at the surface for more than 14 consecutive days during the growing season. They may be difficult to identify because of seasonal fluctuations in the water table or drought (e.g., red maple swamps in New England), vegetation communities that have an atypical distribution of plants (i.e., comprised of plants that also occur in uplands (e.g., hemlock swamps), or soils that are not readily identifiable as hydric (e.g., red parent material soils. See Appendix 6). Forested wetlands typically perform important aquatic functions (e.g., water quality maintenance, stream discharge regulation, and groundwater recharge). Streamside/Riparian Wetlands Streamside and riparian areas may support wetlands that are difficult-to-identify. The rise and fall of stream flow may make hydrology determinations difficult during dry seasons or drought. However, stream gage data may be available to document normal hydrologic conditions. Recent deposits of sediment in river channels or on floodplains may make soils difficult to identify because soils may not have had time to develop typical indicators * 31 ------- of saturation. Streamside and riparian wetlands typically perform important aquatic functions such as water quality maintenance by filtration of floodwaters and upland runoff, streamflow regulation by storing and slowly releasing floodwaters and runoff, and providing aquatic habitats for fish and wildlife. Wet Meadows/Prairie Wetlands Some wet meadow and prairie wetlands are difficult-to-identify. These wetlands may occur near waterways, in depressions or in outwashes in drainageways. They may not exhibit wetland hydrology during dry seasons or drought. These wetlands may have difficult-to-identify vegetation due to the invasion during dry periods by plants usually found in uplands. These wetlands may perform aquatic functions such as water quality maintenance and groundwater recharge. Difficult-to-identify wetlands also include the following specific types: Pocosins The pocosin wetlands of the Southeast contain broadleaved evergreen shrub bogs. Such bogs typically occur in areas characterized by highly organic soils and long hydroperiods during which inundation may but does not always occur. The largest areas of pocosin wetlands occur in the outer Coastal Plain of North Carolina. Although early settlers used the term to depict a variety of swamp vegetation types, pocosin wetlands usually are described as marshy or boggy shrub areas or flatwoods with poor drainage where peaty soils typically support scattered pines and a dense growty of shrubs, mostly evergreen (Sharitz and Gibbons 1982). Hydrology of pocosins may not be readily apparent due to the thick underlying peaty soils that may dry out rapidly after the early part of the growing season due to evapotranspiration. Located on the Coastal Plain, pocosins perform important aquatic functions such as storing rainwater and regulating its discharge into nearby estuaries where aquatic life is affected by fluctuations in streamflow and salinity. Pocosins also function to stabilize nutrients, reducing the potential for nutrient overloading in nearby estuaries. Playas Playas occur in many arid and semiarid regions of the world. Although occurring throughout much of the western United States, they are concentrated in the southern Great Plains as either ephemeral or permanent lakes or wetlands. The topography of roost playa regions is flat to gently rolling and generally devoid of drainage. Playa basins collect water primarily in two peak periods — May and September — as a result of regional 32 ------- convectional storms. Wetland hydrology is best characterized by examining hydrological indicators over a multi-year period. Playa basins may have a dense cover of annual or perennial vegetation or may be barren, depending on the timing and other factors such as precipitation and irrigational runoff. As with potholes, the process of annual drying in playas enables the invasion of FAC, FACU, and UPL plants during dry periods which may persist into other seasons. Playas typically are important waterfowl habitat. Additional information to assist in playa wetland identification is in Appendix 5. Prairie Potholes Prairie potholes are glacially-formed depressional wetlands located in the north central United States and southern Canada. Many prairie potholes are seasonally dry but fill with snowmelt and rain early in the growing season. This is because average precipitation is far too sparse to meet the demands of evaporation and as a result, some potholes are dry for a significant portion of the year. The process of annual drying in potholes enables the invasion of FAC, FACU, or UPL plant species during dry periods which may persist into wet seasons. Nevertheless, a variety of vegetation characteristic of a freshwater marsh can exist in a prairie pothole with submergent and floating plants in deeper water, bulrushes and cattails closer to shore, and sedges located toward the upland. The drastically fluctuating climate and alteration for farming have resulted in highly disturbed conditions that make wetland identification difficult. Potholes are typically known for supporting an abundance of resident and migratory waterfowl. Additional information to assist in prairie pothole wetland identification is in Appendix 5. Vernal Pools Vernal pools are natural wetlands are depressional wetlands that are covered by shallow water for variable periods from winter to spring, but may be completely dry at the surface for most of the summer and fall. They hold water long enough to allow some aquatic organisms (e.g., salamanders and frogs) to grow and reproduce (complete their life cycles), but not long enough to permit the development of a typical pond or marsh ecosystem. Since vernal pools vary considerably in depth and duration of both from year to year, within a year, or between different pools, plant composition is quite dynamic. Depending on the seasonal phase of the pool, plants can range from OBL aquatic plants to FAC and FACU species. Additional information to assist in vernal pool wetland identification is in Appendix 5. 33 ------- FART III. STANDARD METHODS FOR IDENTIFICATION AND DELINEATION OF WETLANDS Four basic approaches for identifying and delineating wetlands have been developed to cover situations ranging from desk-top or office determinations to highly complex field determinations for regulatory purposes. These methods are the recommended approaches that have been successfully used to delineate wetlands by the four Federal agencies. If situations require different approaches, the reasons for departing from recommended approaches should be documented. Remember, however, that any method for making a wetland determination must consider the three technical criteria (i.e., hydrophytic vegetation, hydric soils, and wetland hydrology) listed in Part II of this manual. These criteria must be met in order to identify a wetland. Moreover, procedures for determining the wetland boundary must be consistent with those used in this manual. In applying all methods, relevant available information on wetlands in the area of concern should be collected and reviewed. Table lists primary data sources. Selection of a Method The wetland delineation methods presented in this manual can be grouped into two general types: (1) offsite preliminary procedures and (2) onsite procedures. The offsite procedures are designed for use in the office for preliminary wetland determinations, while onsite procedures are developed for use in the field for definitive wetland determinations. When an onsite inspection is unnecessary or cannot be undertaken for various reasons, available information can be reviewed in the office to make a preliminary wetland determination. If available information is insufficient to make a preliminary wetland determination or if a definitive wetland determination or wetland boundary must be established, (e.g., for determining whether or not there is jurisdiction or the boundaries of jurisdiction under a Federal wetland regulatory program), an onsite inspection should be conducted. For determining whether or not an area is subject to Clean Water Act jurisdiction, an onsite inspection is usually necessary. Depending on the field information needed or the complexity of the area, one of three basic onsite methods may be employed: (1) routine, (2) intermediate-level, or (3) comprehensive. Table presents some examples of when to use each method. The routine method is designed for areas equal to or less than five acres in size or larger areas with homogeneous vegetation. For areas greater than five acres in size or other areas of any size that are highly diverse in vegetation, the intermediate-level method or the comprehensive method should be applied, as necessary* The comprehensive method is applied to situations requiring detailed documentation of vegetation, soils, ------- and hydrology. Assessments of significantly disturbed sites will often require intermediate-level or. comprehensive determinations as well as some special procedures. In other cases where natural conditions make wetland identification difficult, special procedures for difficult-to-identify wetland determinations have been developed. Wetland delineators should become well acquainted with these types of situations (e.g., disturbed and difficult-to-identify wetlands) and the appropriate procedures. In making wetland determinations, one should select the appropriate method for each individual unit within the area of concern and not necessarily employ one method for the entire site. Thus, a combination of determination methods may be used for a given site. Regardless of the method used, the desired outcome or final product is a wetland/nonwetland determination. Depending on one's expertise, available information, and individual or agency preference, there are two basic approaches to delineating wetland boundaries. The first approach involves characterizing plant communities in the area, identifying plant communities meeting the hydrophytic vegetation criterion, examining the soils in these areas to confirm that the hydric soil criterion is met, and finally looking for evidence of wetland hydrology to verify this criterion. This approach has been widely used by the CE and EPA and to a large extent by the FWS. A second approach involves first delineating the approximate boundary of potential hydric soils, and then verifying the presence of likely hydrophytic vegetation and looking for signs of wetland hydrology. This type of approach has been employed by the SCS and to a limited extent by the FWS. Since these approaches yield the same result, this manual incorporates both approaches into most of the methods presented. 35 ------- Table 1. Ita Name Primary sources of information that may be helpful in making a wetland determination. Topographic Maps (mostly 1:24,000; Survey (USGS) 1:63,350 for Alaska) 1-800-USA-MAPS) National Wetlands Inventory Maps Wildlife Service (mostly 1:24,000; 1:63,350 1-800-USA-MAPS) for Alaska) County Soil Survey Reports Conservation Service Offices reports—local district National Hydric Soils List state Hydric Soils List Hydric Soil Map Unit List National Insurance Agency Management Flood Maps Agency Local Wetland Maps agencies Land Use and Land Cover Maps (1-8 00 -USA-MAPS) Aerial Photographs sources— USGS, other Federal and private sources ASCS Compliance Slides Source U.S. Geological (Call U.S. Fish and (FWS) (Call U.S.D.A. Soil (SCS) District (Unpublished offices) SCS National Office SCS State Offices SCS District Offices Federal Emergency State and local USGS Various State agencies, and U.S.D.A. Agricultural Stabilization and Conservation Service Satellite Imagery National List of Plant Species EOSAT Corporation, SPOT Corporation, and others Government Printing 36 ------- Office That Occur in Wetlands Documents (Stock No. 024-010-00682-0) Regional Lists of Plants that Information Occur in Wetlands 22161 National Wetland Plant Database stream Gauge Data and USGS Soil Drainage Guides Data Name Environmental Impact Statements State atgencies and Assessments Published Reports Local Expertise consultants, and others Site-specific Plans and Engineering Designs Superintendent of Washington, DC 20402 National Technical Service 5285 Port Royal Head Springfield, VA (703) 487-4650 FWS CE District Offices SCS District Offices Source Various Federal and Federal and States agencies, universities, and others Universities, Private developers 37 ------- Description of Methods Offsite Preliminary Determinations When an onsite inspection is not necessary because information on hydrology, hydric soils, and hydrophytic vegetation is known or an inspection is not possible due to time constraints or other reasons, a preliminary wetland determination can be made in the office. This approach provides an approximation of the presence of wetland and its boundaries based on available information. The accuracy of the determination depends on the quality of the information used and on one's ability and experience in an area to interpret these data. Where reliable, site-specific data have been previously collected, the wetland determination can be reasonably accurate. Where these data do not exist, more generalized information may be used to make a preliminary wetland determination. In either case, however, if a more accurate delineation is required, then onsite procedures must be employed. For the purposes of determining whether an area is subject to Federal jurisdiction under the Clean Water Act or other Federal wetland regulatory program, onsite determinations are usually necessary. Regardless of the method used, documentation of all three criteria is mandatory. Onsite Determinations When an onsite inspection is necessary, always be sure to review pertinent background information (e.g., NWI maps, soil surveys, and site plans) before going to the subject site. This information will be helpful in determining what type of field method should be employed. Also, read the sections of this manual that discuss disturbed (page 41) and difficult-to-identify (page 31) wetlands before conducting field work. These situations pose significant problems for the inexperienced wetland delineator, so learn the procedures for evaluating these sites. Recommended equipment and materials for conducting onsite determinations are listed in Table • Figures 1, 2, and 3 show the decision process for making onsite wetland determinations by the various approaches presented in the manual. 38 ------- Table 2. Recommended equipment and materials for onsite determinations. Equipment Materials Soil auger, probe, or spade Sighting compass Pen or pencil Penknife Hand lens Vegetation sampling frame* Camera/Film wetland Binoculars Tape measure Prism or angle gauge Diameter tape* Vasculum (for plant collect.) Names Calculator* Dissecting kit Data sheets and clipboard Field notebook Base (topographic) map Aerial photograph Nation Wetlands Inventory map Soil survey or other soil map Appropriate Federal interagency plants list County hydric soil map unit list Munsell soil color book Plant identification field guides/manuals National List of Scientific Plant Flagging tape/wire flags-wooden stakes Plastic bag (for collecting plants and soil samples as needed) •Needed for comprehensive determination 39 ------- For every upcoming field inspection, the following pre-inspection steps should be undertaken: Step 1. Locate the project area on a map (e.g., U.S. Geological Survey topographic nap or SCS soil survey nap) or on an aerial photograph and determine the limits of the area of concern. Proceed to Step 2. Step 2. Estinate the size of the subject area. Proceed to Step 3. Step 3. Review existing background information and determine, to the extent possible, the site's geomorphological setting (e.g., floodplain, isolated depression, or ridge and swale complex), its habitat or vegetative complexity (i.e., the range of habitat or vegetation types), and its soils. (Note: Depending on available information, it may not be possible to determine the habitat complexity without going on the site; if necessary, do a field reconnaissance.) Proceed to Step 4. Step 4. Determine whether a disturbed condition exists. Examine available information and determine whether there is evidence of sufficient natural or human-induced alteration to significantly modify all or a portion of the area's vegetation, soils, and/or hydrology. If such disturbance is noted, identify the limits of affected areas for they should be evaluated separately for wetland determination purposes (usually after evaluating undisturbed areas). The presence of disturbed areas within the subject area should be considered when selecting an onsite determination method. (Note: It may be possible that at any time during this determination, one or more of the three characteristics may be found to be significantly altered. If this happens, follow the disturbed area wetland determination procedures, as necessary, noted on p. 41). Proceed to Step 5. Step 5. Determine the field determination method to be used. Considering the size and complexity of the area and the need for quantification, determine whether a routine, intermediate-level, or comprehensive field determination method should be used. When the area is equal to or less than five acres in size or is larger and appears to be relatively homogeneous with respect to vegetation, soils, and/or hydrology, use the routine method (see below). When the area is greater than five acres in size, or is smaller but appears to be highly diverse with respect to vegetation, use the intermediate-level method (Appendix 3). When detailed quantification of plant communities and more extensive documentation of other factors (soils and hydrology) are required, use the comprehensive method regardless of the wetland's size (Appendix 4). significantly disturbed sites (e.g., sites that have been filled, hydrologically modified, cleared of vegetation, or had their soils altered) will generally require intermediate-level or comprehensive methods. In % 40 ------- these disturbed areas, it usually will be necessary to follow a set of subroutines to determine whether the altered characteristic met the applicable criterion prior to its modification; in the case of altered wetland hydrology, it nay be necessary to determine whether the area is effectively drained. Because a large area may include a diversity of smaller areas ranging from simple wetlands to vegetatively complex areas, one may use a combination of the onsite determination methods, as appropriate. Disturbed Area Wetland Determinations In the course of field investigations, one often encounters significantly disturbed or altered areas. Disturbed areas include situations where field indicators of one or more of the three wetland identification criteria are obliterated or not present due to recent change. The following sections discuss these situations and present procedures for distinguishing wetlands from nonwetlands. Disturbed areas have been altered either recently or in the past in some way that makes wetland identification more difficult than it would be in the absence of such changes. Disturbed areas include both wetlands and nonwetlands that have been modified to varying degrees by human activities (e.g., filling, excavation, clearing, damming, and building construction) or by natural events (e.g., avalanches, mudslides, fire, volcanic deposition, and beaver dans). Disturbed wetlands include areas subjected to deposition of fill or dredged material, removal or other alteration of vegetation, conversion to agricultural land and silviculture plantations, and construction of levees, channelization and drainage systems, and/or dams (e.g., reservoirs and beaver dams) that significantly modify an area's hydrology. In considering the effects of natural events (e.g., a wetland buried by a mudslide), the relative permanence of the change and whether the area is still functioning as a wetland must be considered.. If natural events have relatively permanently disturbed an area to the extent that wetland hydrology is no longer present, and therefore hydric soils and hydrophytic vegetation, even if still present, would not be expected to persist at the site, the area is no longer a wetland. Detailed investigations of the prior condition of such areas is generally inappropriate. In cases where recent human activities have caused these changes, it may be necessary to determine the date of the alteration or conversion for legal purposes. If an illegal disturbance is suspected, and the pre-disturbance condition must be determined for the purposes of wetland regulatory program enforcement purposes, then a detailed investigation of the prior and current conditions of the disturbed area (i.e., whether the area was and is wetland or non-wetland) is appropriate. However, if an area has been disturbed by legal human activities that have effected the relatively permanent removal of wetland hydrology, hydric soil, or hydrophytic vegetation, then the area is non-wetland, and a detailed * 41 ------- investigation of the prior condition of such areas is generally inappropriate. In addition, determination of regulatory jurisdiction for such areas is subject to agency interpretation. For example. Federal wetland regulatory policy under the Clean water Act, and agricultural program policy under the Food Security Act of 1985, as amended, interprets the relative permanence of disturbance to vegetation caused by agricultural cropping. Be sure to consult appropriate agency in making Federal wetland jurisdictional determinations in such areas. In disturbed wetlands, field indicators for one or more of the three technical criteria for wetland identification are usually absent. Where it is necessary to determine whether the "missing" indicator(s) (especially wetland hydrology) existed prior to alteration, one should review aerial photographs, existing maps, and other available information about the site. This determination may involve evaluating a nearby reference site (similar to the original character of the one altered) for indicator(s) of the "altered" characteristic. When a significantly disturbed condition is detected during an onsite determination, and the prior condition of the area must be determined or it is suspected that the area may still be a wetland, the following steps should be taken to determine if the "missing" indicator(s) was present before alteration and whether the criterion in question was originally met. Be sure to record findings on the appropriate data form. After completing the necessary steps in Appendix 4, return to the applicable step of the onsite determination method being used and continue evaluating the site's characteristics. 42 ------- APPENDIX l. Offsite Preliminary Determination Method The following steps are recommended for conducting an offsite wetland determination: Step 1. Locate the area of interest on a U.S. Geological Survey topographic map and delineate the approximate subject area boundary on the map. Note whether marsh or swamp symbols or lakes, ponds, rivers, and other waterbodies are present within the area. If they are, then there is a good likelihood that wetland is present. Proceed to Step 2. Step 2. Review appropriate National Wetlands Inventory (NWi) maps, State wetland maps, or local wetland maps, where available. If these maps designate wetlands in the subject area, there is a high probability that wetlands are present unless there is evidence on hand that the wetlands have been effectively drained, filled, excavated, impounded, or otherwise significantly altered since the effective date of the maps. Proceed to Step 3. Step 3. Review SCS soil survey maps where available. In the area of interest, are there any map units listed on the county list of hydric soil map units or are there any soil map units with significant hydric soil inclusions? If YES, then at least a portion of the project area may be wetland. If this area is also shown as a wetland on NWI or other wetland maps, then there is a very high probability that the area is wetland unless it has been recently altered (check recent aerial photos, Step 4). Areas without hydric soils or hydric soil inclusions should in most cases be eliminated from further review, but aerial photos still should be examined for small wetlands to be more certain. This is especially true if wetlands have been designated on the National Wetlands Inventory or other wetland maps. Proceed to Step 4. Step 4. Review recent aerial photos of the project area. Before reviewing aerial photos, evaluate climatological data to determine whether the photo year had normal or abnormal (high or low) precipitation two to three months, for example, prior to the date of the photo. This will help provide a useful perspective or frame-of-reference for doing photo interpretation. In some cases, aerial photos covering a multi-year period (e.g., 5-7 years) should be reviewed, especially where recent climatic conditions have been abnormal. During photo interpretation, look for one or more signs of wetlands. For example: 1) hydrophytic vegetation; 2) surface water; 3) saturated soils; 4) flooded or drowned out crops; % 43 ------- 5) stressed crops due to wetness; 6) greener crops in dry years; 7) differences in vegetation patterns due to different planting dates. If signs of wetland are observed, proceed to Step 5 when site-specific data are available; if site-specific data are not available, proceed to Step 6. (CAUTION: Accurate photo interpretation of certain wetland types requires considerable expertise. Evergreen forested wetlands, seasonally saturated wetlands, and temporarily flooded wetlands, in general, may present considerable difficulty. If not proficient in wetland photo interpretation, then one can rely more on the findings of other sources, such as NWI maps and soil surveys, or seek help in photo interpretation.) Step 5. Review available site-specific information. In some cases, information on vegetation, soils, and hydrology for the project area has been collected during previous visits to the area by agency personnel, environmental consultants or others. Moreover, individuals or experts having firsthand knowledge of the project site should be contacted for information whenever possible. Be sure, however, to know the reliability of these sources. After reviewing this information, proceed to Step 6. Step 6. Determine whether wetlands exist in the subject area. Based on a review of existing information, a preliminary determination can be made that the area is likely to be a wetland if: 1) Wetlands are shown on NWI or other wetland maps, and hydric soil map unit or a soil map unit with hydric soil inclusions is shown on the soil-survey; or 2) Hydric soil map unit or soil map unit with hydric soil inclusions is shown on the soil survey fNote: in the latter case, only the hydric inclusion is being evaluated as wetland.), and A) site-specific information, if available, confirms hydrophytic vegetation, hydric soils, and wetland hydrology, or 8) wetlands are shown in aerial photos. If, after examining the available reference material one is still unsure whether the area is likely to be wetland, then a field inspection should be conducted, whenever possible. Alternatively, more detailed information on the site's characteristics may be sought, to help make the preliminary determination. * 44 ------- The validity of offsite preliminary determinations are dependent on the availability of information for making a wetland determination, the quality of this information, and one's ability and experience t interpret these data. In most cases, therefore, the offsite procedure yields a preliminary determination. For more accurate results, one must conduct an onsite inspection. to 45 ------- APPENDIX 2. Routine Onsite Determination Method For most cases, wetland determinations can be made in the field without rigorous sampling of vegetation and soils. Two approaches for routine determinations are presented: (1) hydric soil assessment procedure, and (2) plant community assessment procedure. In the former approach, areas that meet or may meet the hydric soil criterion are first identified and then dominant vegetation is visually estimated to determine if hydrophytic vegetation is obvious. If so, the area is designated as wetland. If not, then the site must undergo a more rigorous evaluation following one of the other onsite determination methods presented in the manual. The second routine approach requires initial identification of representative plant community types in the subject area and then characterization of vegetation, soils, and hydrology for each type. After identifying wetland and nonwetland communities, the wetland boundary is delineated. All pertinent observations on the three mandatory wetland criteria should be recorded on an appropriate data sheet; this should be done for all inspections to determine regulatory -Jurisdiction. Hydric Soil Assessment Procedure Step 1. Identify the approximate limits of areas that may meet the hydric soil criterion within the area of concern and sketch limits on an aerial photograph. To help identify these limits use sources of information such as Agricultural Stabilization and Conservation slides, soil surveys, NWI maps, and other maps and photographs. (Note; This step is more convenient to perform offsite, but may be done onsite.) Proceed to Step 2. Step 2. Scan the areas that may meet the hydric soil criterion and determine if disturbed conditions exist. Are any significantly disturbed areas present? If YES, identify their limits for they should be evaluated separately for wetland determination purposes (usually after evaluating undisturbed areas). Refer to the section on disturbed areas (p. 41), if necessary, to evaluate the altered characteristic(s) (vegetation, soils, or hydrology). If appropriate, determine whether wetland regulatory policy exempts the area from Federal regulatory jurisdiction (e.g., regulatory policy on wetlands converted to cropland. See Disturbed Areas discussion, p.85); then return to this method and continue evaluating characteristics not altered. (Note; Prior experience with disturbed sites may allow one to easily evaluate an altered characteristic, such as when vegetation is not present in a farmed wetland due to cultivation*)- Keep in mind that if at any time during this determination, one or more of these three characteristics are found to have been significantly altered, the disturbed area determination procedures should be followed. If the area is not significantly disturbed, proceed to Step 3. 46 ------- Step 3. Scan the areas that may meet the hydric soil criterion and determine if obvious signs of wetland hydrology or hydric soil are present. The wetland hydrology criterion is met for any area or portion thereof where it is obvious or known that the area is frequently inundated or saturated to the surface for a sufficient duration during the growing season in most years. If the above condition exists, the hydric soil criterion is presumed to be met for the subject area and the area is considered wetland. If necessary, confirm the presence of readily identified hydric soil by examining the soil for appropriate properties. If the area's hydrology has not be significantly disturbed and the soil is organic (Histosols, except Folists) or is mineral classified as Sulfaquents, Hydraquents, or Histic subgroups of Aquic Suborders, the area is also considered wetland. fNotei The hydrophytic vegetation criterion is presumed to be met under these conditions, i.e., undrained hydric soil, so vegetation does not need to be examined. Moreover, hydrophytic vegetation should be obvious in these situations; however you may need to record dominant species for future references) Areas lacking obvious indicators of wetland hydrology or readily obvious hydric soils must be further examined, so proceed to Step 4. Step 4. Refine the boundary of areas that may meet the hydric soil criterion. Verify the presence of hydric soil within the appropriate map units by digging a number of holes at least 18 inches deep along the boundary (interface) between hydric soil units and nonhydric soil units. Compare soil samples with descriptions in the soil survey report to see if they are properly mapped. In this way, the boundary of areas meeting the hydric soil criterion is further refined by field observations. In map units where only part of the unit is hydric (e.g., complexes, associations, and inclusions), locate hydric soil areas on the ground by considering landscape position and evaluating soil characteristics for hydric soil properties. (Note; Some hydric soils, especially organic soils, have not been given a series name and are referred to by common names, such as peat, muck, swamp, marsh, wet alluvial land, tidal marsh, Sulfaquents, and Sulfihemists. These areas are also considered hydric soil map units. Certain hydric soils are mapped with nonhydric soils as an association or complex, while other hydric soils occur as inclusions in nonhydric map units. Only the hydric soil portion of these map units should be evaluated for the hydrophytic vegetation criteria in Step 7.) If the area meets the hydric soil criterion, proceed to Step 5. Step 5. Consider the following: 1) Is the area presently lacking hydrophytic vegetation or hydrologic indicators due to annual, seasonal or long-term fluctuations in precipitation, surface water, or ground-water levels? 2) Are hydrophytic vegetation indicators lacking due to » 47 ------- seasonal fluctuation in temperature (e.g., seasonality of plant growth)? If the answer to either of these questions is YES or uncertain, proceed to the section on difficult-to-identify wetland discussion (p.31). If the answer to both questions is NO, normal conditions are assumed to be present, so proceed to Step 6. mote; In some cases, normal climatic conditions, such as snow cover or frozen soils, may prevent an accurate assessment of the wetland criteria; one must use best professional judgement to determine if delaying the wetland delineation is appropriate.) Step 6. Select representative observation area(s). Identify one or more observation areas that represent the area(s) meeting the hydric soil criterion. A representative observation area is one in which the apparent characteristics (determined visually) best represent characteristics of the entire community. Mark the approximate location of the observation area(s) on the aerial photo. Proceed to Step 7. Step 7. Characterize the plant community within the area(s) meeting the hydric soil criterion. Visually estimate the percent areal cover of dominant species for the entire plant community. If dominant species are not obvious, use one of the other onsite methods. Proceed to Step 8 or to another method, as appropriate. Step 8. Record the indicator status of dominant species within each area meeting the hydric soil criterion. Indicator status is obtained from the interagency Federal list of plants occurring in wetlands for the appropriate geographic region. Record information on an appropriate data form. Proceed to Step 9. Step 9. Determine whether wetland is present or additional analysis is required. If the estimated percent areal cover of OBL and FACW species (dominants) exceeds that of FACU and UPL species (dominants), the'area is considered wetland and the wetland-nonwetland boundary is the line delineated by the limits of conditions that verify the wetland hydrology criterion (see p. 10). If not, then the point intercept or other sampling procedures should be performed to do a more rigorous analysis of site characteristics. Plant Community Assessment Procedure Step 1. Scan the entire project area, if possible, or walk, if necessary, and identify plant community types present. In identifying- communities, pay particular attention to changes in elevation throughout the site. (CAUTION: In highly variable sites, such as ridge and swale complexes, be sure to stratify properly, i.e., divide the site into homogeneous landforms to evaluate each landform separately.) If possible, sketch the approximate location of each plant community on a base map, an aerial photograph of the 48 ------- project area, or a county soil survey nap and label each community with an appropriate name. fNote; For large homogeneous wetlands, especially marshes dominated by herbaceous plants and shrub bogs dominated by low-growing shrubs, it is usually not necessary to wall the entire project area. In these cases, one can often see for long distances and many have organic mucky soils that can be extremely difficult to walk on. Forested areas, however, will usually require a walk through the entire project area.) In examining the project area, are any significantly disturbed areas observed? If YES, identify their limits for they should be evaluated separately for wetland determination purpose (usually after evaluating undisturbed areas). Refer to the section on disturbed areas (p.41) to evaluate the altered characteristic(s) (i.e., vegetation, soils, or hydrology). If appropriate, determine whether wetland regulatory policy exempts the area from Federal regulatory jurisdiction (e.g., regulatory policy on wetlands converted to cropland); then return to this method to continue evaluating characteristics not altered. Keep in mind that if at any time during this determination one or more of these three characteristics are found to have been significantly altered, the disturbed area procedures should be followed. If the area is not significantly disturbed, proceed to Step 2. Step 2. Consider the following: 1) Is the area presently lacking hydrophytic vegetation or hydrologic indicators due to annual, seasonal or long-term fluctuations in precipitation, surface water, or ground-water levels? 2) Are hydrophytic vegetation indicators lacking due to seasonal fluctuations in temperature (e.g., seasonality of plant growth)? If the answer to either of these questions is YES or uncertain, proceed to the section on difficult-to-identify wetland determinations (p.31). If the answer to both questions is NO, normal conditions are assumed to be present, so proceed to Step 3. fNote: In some cases, normal climatic conditions, such as snow cover or frozen soils, may prevent an accurate assessment of the wetland criteria; one must use best professional judgement to determine if delaying the wetland delineation is appropriate.) Step 3. Select representative observation area(s). Select one or more representative observation areas within each community type. A representative observation area is one in which the apparent characteristics (determined visually) best represent characteristics of the entire community. Mark the approximate location of the observation areas on the base map or photo. Proceed to Step 4. 49 ------- Step 4. Characterize each plant community in the project area. Within each plant community identified in Step 1, visually estimate the dominant plant species for each valid vegetative stratum in the representative observation areas and record them on an appropriate data form. Vegetative strata may include tree, sapling, shrub, herb, woody vine, and bryophyte strata (see glossary for definitions). Make sure the size of the observation area is sufficient to insure a representative assessment of the plant community. A separate form must be completed for each plant community identified for wetland determination purposes. After identifying dominants within each vegetative stratum, proceed to Step 5. Step 5. Record the indicator status of dominant species in all strata. Indicator status is obtained from the interagency Federal list of plants occurring in wetlands for the appropriate geographic region. Record indicator status for all dominant plant species on a data form. Proceed to Step 6. Step 6. Determine whether the hydrophytic vegetation criterion is met. When more than 50 percent of the dominant species in each community type have an indicator status of OBL, FACW, and/or FAC, the hydrophytic vegetation criteria is met. Complete the vegetation section of the data form. Portions of the project area failing this test are usually not wetlands, although under certain circumstances they may have wetland hydrology and therefore be wetland (see list of difficult-to-identify wetlands on p.31). Proceed to Step 7. Step 7. Determine whether soils must be characterized or additional analysis is needed. Examine vegetative data collected for each plant community (in Steps 5 and 6) and identify any plant community where OBL species or OBL and FACW species predominate the list of dominant plant species. In the absence of significant hydrologic modification, these plant communities are considered wetland (i.e., the hydric soil and wetland hydrology criteria are presumed to be met), but it may be advisable to record observations of hydric soils and wetland hydrology, if assessing wetlands for regulatory purposes; proceed to Steps 9 and 10 and quickly record indicators of these criteria. Similarly, plant communities where UPL species or UPL and FACU species predominate the list of dominants are considered nonwetland. (CAUTION: Make sure that this plant community is not a difficult-to-identify wetland, see p. 31.) Proceed to Step 11. Plant communities lacking the above characteristics must have soils closely examined; proceed to Step 8. Step 8. Determine whether the hydric soil criterion is met. Locate the observation area on a county soil survey map, if possible, and determine the soil map unit delineation for the area. Using a soil auger, probe, or spade, make a hole at least 18 inches deep at the representative location in each plant community type. Examine soil characteristics and compare if possible to soil descriptions in the county soil survey report or classify to Subgroup following "Soil Taxonomy" (often reguires digging a deeper > 50 ------- hole), or look for regional indicators of significant soil saturation If soil has been plowed or otherwise altered, which may have eliminated these indicators/ proceed to the section on disturbed areas (p. 41). Complete the soils section on the appropriate data sheet and proceed to Step 9 if conditions satisfy the hydric soil criterion. Areas having soils that do not meet the hydric soil criterion are nonwetlands. (CAUTION: Become familiar with problematic hydric soils that do not possess good hydric field indicators, such as red parent material soils, some sandy soils, and some floodplain soils, so that these hydric soils are not misidentified as nonhydric soils; see the difficult-to-identify wetlands discussion on p.31.) Step 9. Determine whether the wetland hydrology criterion is met. Record observations and complete the hydrology section on the appropriate data form. If the wetland hydrolgy criterion is met, proceed to Step 10. If the wetland hydrology criterion is not met, the area is nonwetland. (CAUTION: Seasonally saturated wetland may not appear to meet the hydrology criterion at certain times of the growing season; see discussion of difficult-to-identify wetlands, page 31). Step 10. Make the wetland determination. Examine data forms for each plant community identified in the project area. Each community meeting the hydrophytic vegetation, hydric soil, and wetland hydrology criteria is considered wetland. If all communities meet these three criteria, then the entire project area is a wetland. If only a portion of the project area is wetland, then the wetland-nonwetland boundary must be established. Proceed to Step n.| Step 11. Determine the wetland-nonwetland boundary. Where a base map or annotated photo was prepared, mark each plant community type on the map or photo with a "W" if wetland or an "N" if nonwetland. Combine all "Ww types into a single mapping unit, if possible, and all."N" types into another mapping unit. On the map or photo, the wetland boundary will be represented by the interface of these mapping units. If flagging the boundary on the ground, the boundary is established by determining the limits of the indicators that verify all three criteria. 51 ------- APPENDIX 3. intermediate-level Onsite Determination Method On occasion, a more rigorous sampling method is required than the routine method to determine whether hydrophytic vegetation is present at a given site, especially where the boundary between wetland and nonwetland is gradual or indistinct. This circumstance requires more intensive sampling of vegetation and soils than presented in the routine determination method. This method also may be used for areas greater than five acres in size or other areas that are highly diverse in vegetation. The intermediate-level onsite determination method has been developed to provide for more intensive vegetation sampling than the routine method. Two optional approaches are presented: (1) quadrat transect sampling procedure, and (2) vegetation unit sampling procedure. The former procedure involves establishing transects within the project area and sampling plant communities along the transect within sample quadrats, with soils and hydrology also assessed as needed in each sample plot. In contrast, the vegetation unit sampling procedure offers a different approach for analyzing the vegetation. First, vegetation units are designated in the project area and then a meander survey is conducted in each unit where visual estimates of percent areal coverage by plant species are made. Soil and hydrology observations also are made as necessary. Boundaries between wetland and nonwetland are established by examining the transitional gradient between them. The following steps should be completed: Step 1. Locate the limits of the project area in the field and conduct a general reconnaissance of the area. Previously the project boundary should have been determined on aerial photos or maps. Now appropriate ground reference points need to be located to insure that sampling will be conducted in the proper area. In examining the project area, were any significantly disturbed areas observed? If YES, identify their limits for they should be evaluated separately for wetland determination purposes (usually after evaluating undisturbed areas). Refer to the section on disturbed areas (p. 41) to evaluate the altered characteristic(s) (i.e., vegetation, soils, or hydrology); then return to this method to continue evaluating the characteristics not altered. Keep in mind that if at any time during this determination, one or more of these three characteristics is found to have been significantly altered, the disturbed areas procedures should be followed. If the area is not significantly disturbed, proceed with Step 2. Step 2. Decide how to analyze plant communities within the project area: (1) by selecting representative plant communities (vegetation units), or (2) by sampling along a transect. Discrete vegetation units may be identified on aerial photographs, topographic and other maps, and/or by field inspection. These units * 52 ------- will be evaluated for hydrophytic vegetation and also for hydric soils and wetland hydrology, as necessary, if the vegetation unit approach is selected, proceed to Step 3. An alternative approach is to establish transects for identifying plant communities, sampling vegetation and evaluating other criteria, as appropriate. If the transect approach is chosen, proceed to Step 4. Step 3. Identifying vegetation units for sampling. Vegetation units are identified by examining aerial photographs, topographic maps, NWI maps, or other materials or, by direct field inspection. All of the different vegetation units present in the project area should be identified. The subject area should be traversed and different vegetation units specifically located prior to conducting the sampling. Field inspection may refine previously identified vegetation units, as appropriate. It may be advisable to divide large vegetation units into subunits for independent analysis. (CAUTION: In highly variable terrain, such as ridge and swale complexes, be sure to stratify properly.) Decide which plant community to sample first and proceed to Step 7. Step 4. Establish a baseline for locating sampling transects. Select as a baseline one project boundary or a conspicuous feature, such as road, in the project area. The baseline should be more or A less parallel to the major watercourse through the area, if presen^F or perpendicular to the hydrologic gradient (see Figure ). Determine the approximate baseline length. Proceed to Step 5. Step 5. Determine the minimum number and position of transects. Use the following to determine the minimum number and position of transects (specific site conditions may necessitate changes in intervals or additional transects). Divide the baseline length by the number of required transects to establish baseline segments for sampling. Establish one transect in each resulting baseline segment (see Figure 1). Use the midpoint of each baseline segment as a transect starting point. For example, if the baseline is 1,200 feet in length, three transects would be established: one at 200 feet, one at 600 feet, and one at 1,000 feet from the baseline starting point. Make sure that all plant community types are included within the transects; this may necessitate relocation of one or more transect lines or establishing more transects. Each transect should extend perpendicular to the baseline (see Figure 4J. Once positions of transect lines are established, go to the beginning of the first transect and proceed to Step 6. Step 6. Locate sample plots along the transect. Along each transect, sample plots are established within each plant community encountered to assess vegetation, soils, and hydrology. When identifying these sample plots, two approaches may be followed: (1) walk the entire length of the transect, taking note of the number, type, and location of plant communities present (flag the location/ 53 ------- if necessary), and on the way back to the baseline, identify plots and perform sampling, or (2) identify plant communities as the transect is walked and sample the plot at that time ("sample as you go11}. The sample plot should be located so it is representative of the plant community type. When the plant community type is large and covers a significant distance along the transect, select an area that is no closer than 300 feet to a perceptible change in plant community type; mark the center of this area on the base map or photo and flag the location in the field, if necessary. (CAUTION: In highly variable terrain, such as ridge and swale complexes, be sure to stratify properly to ensure best results.) At each plant community, proceed to Step 7. Step 7. Consider the following: 1) Is the area presently lacking hydrophytic vegetation or hydrologic indicators due to annual, seasonal, or long-term fluctuations in precipitation, surface water, or ground-water levels? 2) Are hydrophytic vegetation indicators lacking due to seasonal fluctuations in temperature (e.g., seasonality of plant growth)? If the answer to either of these questions is YES or uncertain, proceed to the section on difficult-to-identify wetlands (p.31), then return to this method and continue the wetland determination. If the answer to both questions is NO, normal conditions are assumed to be present, so proceed to Step 8. (Note: In some cases, normal climatic conditions, such as snow cover or frozen soils, may prevent an accurate assessment of the wetland criteria; one must use best professional judgement to determine if delaying the wetland delineation is appropriate.) Step 8. Characterize the vegetation of the vegetation unit or the plant community along the transect. If analyzing vegetation units, meander through the unit making visual estimates of the percent area covered for each species in the herb, shrub, sapling, woody vine, and tree strata; alternatively, for the tree stratum determine basal area using the Bitterlich method (see Dilworth and Bell 1978; Avery and Burkhart 1983). Then: 1) Within each stratum determine and record the cover class of each species and its corresponding midpoint. The cover classes (and midpoints) are: T - <1% (none); 1 - 1-5% (3.0); 2 » 6-15% (10.5); 3 » 16-25% (20.5); 4 « 26-50% (38.0); 5 - 51-75% (63.0); 6 « 76-95% (85.5); 7 - 96-100% (98.0). 2) Rank the species within each stratum according to their midpoints. (Note; If two or more species have the same midpoints and the same or essentially the same recorded percent areal cover, 54 ------- rank them equal; us* absolute areal cover values as a tie-breaker only if they are obviously different.) 3) Sum the midpoint values of all species within each stratum. 4) Multiply the total midpoint values for each stratum by 50 percent. (Note: This number represents the dominance threshold number and is used to determine dominant species.) 5) Compile the cumulative total of the ranked species in each stratum until 50 percent of the sum of the midpoints (i.e., the dominance threshold number), for the herb, woody vine, shrub, sapling, and tree strata (or alternatively basal area for trees) is immediately exceeded. All species contributing areal cover or basal area to the 50 percent threshold are considered dominants, plus any additional species representing 20 percent or more of the total cover class midpoint values for each stratum or the basal area for tree stratum. (Note; If the threshold is reached by two or more equally ranked species, consider them all dominants, along with any higher ranked species. If all species are equally ranked, consider them all dominants.) 6) Record all dominant species on an appropriate data sheet and list indicator status of each. Proceed to Step 9. If using the transect approach, sample vegetation in each stratum (e.g., tree, shrub, herb, etc.) occurring in the sample plots using the following quadrat sizes: (1) a 5-foot radius for bryophytes and herbs, and (2) a 30-foot radius for trees, saplings, shrubs, and woody vines. Plot size and shape may be changed as necessary to meet site conditions, but be sure that it is sufficient to adequately characterize the plant community. Determine dominant species for each stratum by estimating one or more of the following as appropriate: (1) relative basal area (trees); (2) areal cover (trees, saplings, shrubs, herbs, woody vines, and bryophytes); or (3) stem density (shrubs, saplings, herbs, and woody vines), when estimating areal cover, use cover classes T (trace) through 7 and use the midpoints of the cover classes to determine dominants, see substeps 1 through 5 above. All plants covering the plot and representative of the plant community under evaluation should be counted in the cover estimate; plants overhanging from adjacent plant communities should not be counted. Record all dominant species on an appropriate data sheet and list the indicator status of each. Proceed to Step 9. Step 9. Determine whether the hydrophytic vegetation criterion is met. When more than 50 percent of the dominant species in the vegetation unit or sample plot have an indicator status of OBL, FACW, and/or FAC, hydrophytic vegetation is present. If the vegetation fails to be dominated by these types of species, the unit or plot is usually not wetland, but check difficult-to-identify wetlands and disturbed areas discussions for exceptions (pages 31 55 ------- and 41, respectively). If the hydrophytic vegetation criterion is net, Proceed to Step 10 after completing the vegetation section of the data sheet. Step 10. Determine whether soils must be characterized or additional analysis is needed. Examine vegetative data collected for the vegetation unit or plot (in Steps 8 and 9) and identify any plant community (units or plots) where OBL species or OBL and FACW species predominate the list of dominants. In the absence of significant hydrologic modification, these plant communities are typically wetland (i.e., the hydric soil and wetland hydrology criteria are presumed to be met), but it may be adviseable to record indicators for the other criteria, especially if making a wetland determination for regulatory purposes; proceed to Steps ll and 12 as necessary and record appropriate indicators.. Similarly, plant communities where UPL species or UPL and FACU species predominate the list of dominants are considered nonwetland. (CAUTION: Make sure that this plant community is not a difficult-to-identify wetland, see pp. 31). Proceed to Step 12. Plant communities (e.g., vegetation units or plots) lacking the above characteristics must have soils closely examined; proceed to Step 11. Step 11. Determine whether the hydric soil criterion is met. Locate the observation area on a county soil survey map, if possible, and determine the soil map unit delineation for the area. Using a soil auger, probe, or spade, make a hole at least 18 inches deep at the representative location in each plant community type. Examine soil characteristics and compare if possible to soil descriptions in the county soil survey report or classify to Subgroup following "Soil Taxonomy" (often requires digging a deeper hole), or look for regional indicators of significant soil saturation. If soil has been plowed or otherwise altered, which may have eliminated these indicators, proceed to the section on disturbed areas (p.41). Complete the soils section on the appropriate data sheet and proceed to Step 12 if conditions satisfy the hydric soil criterion. Areas having soils that do not meet the hydric soil criterion are nonwetlands. (CAUTION: Become familiar with hydric soils that do not possess good hydric field indicators, such as red parent material soils, some sandy soils, and some floodplain soils, so that these hydric soils are not misidentified as nonhydric soils; see the difficult-to-identify wetlands discussion on p.31). Step 12. Determine whether the wetland hydrology criterion is met. Record observations and complete the hydrology section on the appropriate data form. If the wetland hydrolgy criterion is met, proceed to Step 13. If the wetland hydrology criterion is not net, the area is nonwetland. (CAUTION: Seasonally saturated wetland may not appear to meet the hydrology criterion at certain times of the growing season; see discussion of difficult-to-identify wetlands, page 31). 56 ------- Step 13. Make the wetland determination for the plant or vegetation unit. Examine the data f ~~~~?s for the plant community (sample plot) or vegetation unit. Wher r.e community or unit meets the hydrophytic vegetation, hydric so;1. and wetland hydrology criteria, the area is considered wetla-.i. Complete the summary data sheet; proceed to Step 14 when continuing to sample the transect or other vegetation units, or to Step 15 when determining, a boundary between wetland and nonwetland plant communities or units. (Note; Before going on, double check all data sheets to ensure that the forms are completed properly.) Step 14. Sample other plant communities along the transect or other vegetation units. Repeat Steps 6 through 13 for all remaining plant communities along the transect if following transect approach, or repeat Steps 7 through 13 at the next vegetation unit. When sampling is completed for this transect, proceed to Step 15, or when sampling is completed for all vegetation units, proceed to Step 16. Step 15. Determine the wetland-nonwetland boundary point along the transect. When the transect contains both wetland and nonwetland plant communities, then a boundary must be established. Proceed along the transect from the wetland plot toward the nonwetland plot. Look for the occurrence of UPL and FACU species, the appearance of nonhydric soil types, subtle changes in hydrologic indicators, and/or slight changes in topography. When such features are noted, look closely for evidence of wetland hydrology in the soil (see p. ) and locate the wetland boundary (i.e., the point at which the wetland hydrology criterion is no longer met). Establish sample plots on each side of the boundary (e.g., within 50 feet) and repeat Steps 8 through 13. If existing plots are within a reasonable distance, additional plots may not be necessary, but always identify the features that were used to identify the boundary. Data sheets should be completed for each new plot. Mark the position of the wetland boundary point on the base map or photo and stake or flag the boundary in the field, as necessary. Continue along the transect until the boundary points between all wetland and nonwetland plots have been established. (CAUTION: In areas with a high interspersion of wetland and nonwetland plant communities, several boundary determinations will be required.) When all wetland determinations along this transect have been completed, proceed to Step 17. Step 16. Determine the wetland-nonwetland boundary between adjacent vegetation units. Review all completed copies of the data sheets for each vegetation unit. Identify each unit as either wetland (W) or nonwetland (N). When adjacent vegetation units contain both wetland and nonwetland communities, a boundary must be established. Walk the interface between the two units from the wetland unit toward the nonwetland unit and look for changes in vegetation, soils, hydrologic indicators, and/or elevation. As a general rule, at 100-foot intervals or whenever changes in the vegetation unit's characteristics are noted, look for evidence to locate the wetland-nonwetland boundary. At each designated boundary 57 ------- point, complete data sheets for new observation areas immed.iatg.iy upslope and downslope of the wetland-nonwetland boundary (i.e., one set for the wetland unit and one for the nonwetland unit), repeat Steps 8 through 13 for each area, and record the distance and compass directions between the boundary points. Record evidence of wetland hydrology as close to the boundary as possible, and record the features that were used to delineate the boundary. Mark the position of the wetland boundary point on the base nap or photo and stake or flag the boundary in the field, as necessary. Based on observations along the interface, identify other of boundary points between each wetland unit and nonwetland unit. Repeat this step for all adjacent vegetation units of wetland and nonwetland. When wetland boundary points between all adjacent wetland and nonwetland units have been established, proceed to Step 18. Step 17. Sample other transects and make wetland determinations along each. Repeat Steps 5 through 15 for each remaining transect. When wetland boundary points for all transects have been established, proceed to Step 18. Step 18. Determine the wetland-nonwetland boundary for the entire project area. Examine all completed copies of the data sheets, and mark the location of each plant community type along the transect on the base map or photo, when used. (Note: This has already been done for the vegetation unit approach.) Identify each plant community as either wetland (W) or nonwetland (N), if it has not been done previously. If all plant communities are wetlands, then the entire project area is wetland. If all communities are nonwetlands, then the entire project area is nonwetland. If both wetlands and nonwetlands are present, identify the boundary points on the base map and connect these points on the map by generally following contour lines to separate wetlands from nonwetlands. Confirm this boundary by walking the contour lines between the transects or vegetation units, as appropriate. Should anomalies be encountered, it will be necessary to establish short transects in these areas to refine the boundary; make any necessary adjustments to the boundary on the base map and/or on the ground. If those areas are significant in scope, be sure to record data used for the boundary determination. When marking the boundary for subsequent surveying by engineers, the boundary points should be flagged or marked otherwise to facilitate the survey. 58 ------- APPENDIX 4. Comprehensive Onsite Determination Method The comprehensive determination method is the most detailed, complex, and labor-intensive approach of the three recommended types of onsite determinations. It is usually reserved for highly complicated and/or large project areas, and/or when the determination requires rigorous documentation. Due to the latter situation, this type of onsite determination may be used for areas of any size. In applying this method, a team of experts, including a wetland ecologist and a soil scientist, is often needed, especially when rigorous documentation of plants and soils are required. It is possible, however, for a highly trained wetland boundary specialist to singly apply this method. Two alternative approaches of the comprehensive onsite determination method are presented: (1) quadrat sampling procedure and (2) point intercept sampling procedure. The former approach establishes quadrats or sampling areas in the project site along transects, while the latter approach involves a frequency analysis of vegetation at sampling points along transects. The point intercept sampling procedure requires that the limits of potential hydric soils be established prior to evaluating the vegetation. In many cases, soil maps are available to meet this requirement, but in other cases a soil scientist may need to inventory the soils applying this method. The quadrat sampling procedure, which identifying plant communities along transects and analyzing vegetation, soils, and hydrology within sample plots (quadrats) , be the preferred approach when soil maps are unavailable or the individual is more familiar with plant identification. may Quadrat Sampling Procedure Prior to implementing this determination procedure, read the sections of this manual that discuss disturbed area and difficult- to- identify wetland section (p. 31) ; this information is often relevant to project areas requiring a comprehensive determination. Step 1. Locate the limits of the project area in the field. Previously, the project boundary should have been determined on aerial photos or maps. Now appropriate ground reference points need to be located to ensure that sampling will be conducted in the proper area. Proceed to Step 2. Step 2. Stratify the project area into different plant community types. Delineate the locations of these types on aerial photos or base maps and label each community with an appropriate name. (CAUTION: In highly variable terrain, such as ridge and swale complexes, be sure to stratify properly to ensure best results.) % 59 ------- evaluating the subject area, were any significantly disturbed areas observed? If YES, identify their limits for they should be evaluated separately for wetland determination purposes (usually after evaluating undisturbed areas). Refer to the section on disturbed areas (p.85) to evaluate the altered characteristic(s) (i.e., vegetation, soils, and/or hydrology); then return to this method to continue evaluating the characteristics not altered. Keep in mind that if at any time during this determination, it is found that one or more or these three characteristics have been significantly altered, the disturbed areas wetland determination procedures should be followed. If the area is not significantly disturbed, proceed to Step 3. Step 3. Establish a baseline for locating sampling transects. Select as a baseline one project boundary or a conspicuous feature, such as a road, in the project area. The baseline ideally should be more or less parallel to the major watercourse through the area, if present, or perpendicular to the hydrologic gradient (see Figure 1). Determine the approximate baseline length and record its origin, length, and compass heading in a field notebook. When a limited number of transects are planned, a baseline may not be necessary provided there are sufficient fixed points (e.g., buildings, walls, and fences) to serve as starting points for the transects. Proceed to Step 4. Step 4. Determine the required number and position of transects. The number of transects necessary to adequately characterize the site will vary due to the area's size and complexity of habitats. In general, it is best to divide the baseline into a number of equal segments and use the mid-point of each baseline segment as the transect starting point (see Figure „_). For example, if the baseline is 1,600 feet in length, four transects will be established; one at 200 feet, one at 600 feet, one at 1,000 feet, and one at 1,400 feet from the baseline starting point. Each transect should extend perpendicular to the baseline. Use the following as a guide to determine the minimum number of baseline segments: *If the baseline exceeds five miles, baseline segments should be 0.5 mile in length. Make sure that each plant community type is included in at least one transect; if not, modify the sampling design accordingly by relocating one or more transect lines or by establishing additional transects. When the starting points for all required transects have been established, go to the beginning of the first transect and proceed to Step 5. Step 5. Identify sample plots along the transect. Along each transect, sample plots may be established in two ways: (1) within each plant community encountered (the plant community transect 60 ------- sampling approach); or (2) at fixed intervals (the fixed interval transect sampling approach); these plots will be used to assess vegetation, soils, and hvdroloov. fe*.a*<9«*>>, ««•«!£,*Aiiy apt"* wawuj i uue vegetation, soils, and hydrology When employing the plant community transect sampling approach, two techniques for identifying sample plots may be followed: (1) walk the entire length of the transect, taking note of the number, type, and location of plant communities present (flag the locations, if necessary) and on the way back to the baseline, record the length of the transect, identify sample plots and perform sampling; or (2) identify plant communities as the transect is walked, sample the plot at that time ("sample as you go"), and record the length of the transect. When conducting the fixed interval transect sampling approach, establish sample plots along each transect using the following as a guide: The first sample plot should be established at a distance of 50 feet from the baseline. When obvious nonwetlands occupy a long segment of the transect from the baseline, begin the first plot in the nonwetland at approximately 300 feet from the point where the nonwetland begins to intergrade into a potential wetland community type. Keep in mind that additional plots will be required to determine the wetlancl-nonwetland boundary between fixed points. In large areas having a mosaic of plant communities, one transect may contain several wetland boundaries. If obstacles such as a body of water or impenetrable thicket prevent access through the length of the transect, access from the opposite side of the project area may be necessary to complete the transect; take appropriate compass reading and location data. At each sample plot (i.e., plant -community or fixed interval area), proceed to step 6. Step 6. Consider the following: 1) Is the area presently lacking hydrophytic vegetation or hydrologic indicators due to annual, seasonal or long-term fluctuations in precipitation, surface water, or ground-water levels? 2) Are hydrophytic vegetation indicators lacking due to seasonal fluctuations in temperature (e.g., seasonality of plant growth)? If the answer to either of these questions is YES or uncertain, proceed to the section on difficult-to-identify wetland determinations (p. 31). If the answer to both questions is NO, normal conditions are assumed to be present. Proceed to Step 7 when following the plant community transect approach. If following the fixed interval approach, go to the appropriate fixed point along thj 61 ------- transect and proceed to Step 8. (Note: in some cases, normal climatic conditions, such as snov cover or frozen soils, may prevent an accurate assessment of the wetland criteria; one must use best professional judgement to determine if delaying the wetland delineation is appropriate,) Step 7. Locate a sample plot in the plant community type encountered. Choose a representative location along the transect in this plant community. Select an area that is no closer than 50 feet from the baseline or from any perceptible change in the plant community type. Mark the center of the sample plot on the base map or photo and flag the point in the field. Additional sample plots should be established within the plant community at 300-foot intervals along the transect or sooner if a different plant community is encountered. (Note; In large-sized plant communities, a sampling interval larger than 300 feet may be appropriate, but try to use 300-foot intervals first.) Proceed to Step 8. Step 8. Lay out the boundary of the sample plot. A circular sample plot with a 30-foot radius should usually be established, however, the size and shape of the plot may be changed to match local conditions (e.g., narrow ridges and swales) as necessary. At the flagged center of the plot, use a compass to divide the circular plot into four equal sampling units at 90*, 180*, 270', and 360'. Mark the outer points of the plot with flagging. Proceed to Step 9. Step 9. Characterize the vegetation and determine dominant species within the sample plot. Sample the vegetation in each layer or stratum (i.e., tree, sapling, shrub, herb, woody vine, and bryophyte) within the plot using the following procedures for each vegetative stratum and enter data on appropriate data sheet (see Appendix for examples of data sheet): 1) Herb stratum A) Sample this stratum using corresponding approach: (1) Plant community transect sampling approach: (a) Select one of the following designs: (i) Eight (8) - 8" x 20" sample quadrats (two for each sampling unit within the circular plot); or (ii) Four (4) - 20" x 20" sample quadrats (one for each sample unit within the plot); or (iii) Four (4) - 40" x 40" sample quadrats (one for each sample unit). 62 ------- .: Alternate shapes of sample quadrats are acceptable provided they are similar in area to those listed above.) (b) Randomly toss the quadrat frame into the understory of the appropriate sample unit of the plot. (c) Record percent areal cover of each plant species. (d) Repeat (b) and (c) as required by the sampling scheme. (e) Construct a species area curve (see example, Appendix ) for the plot to determine whether the number of quadrats sampled sufficiently represent the vegetation in the stratum; the number of samples necessary corresponds to the point at which the curve levels off horizontally; if necessary, sample additional quadrats within the plot until the curve levels off. (f) For each plant species sampled, determine the average percent areal cover by summing the percent areal cover for all sample quadrats within the plot and dividing by the total number of quadrats (see example, Appendix }. Proceed to substep B below. (2) Fixed interval sampling approach: (a) Place one (1) - 40" x 40" sample quadrat centered on the transect point. (b) Determine percent areal coverage for each species. Proceed to substep B below. B) Rank plant species by their average percent areal cover, beginning with the most abundant species. C) Sum the percent cover (fixed interval sampling approach) or average percent cover (plant community transect sampling approach). D) Determine the dominance threshold number - the number at which 50 percent of the total dominance measure (i.e., total cover) for the stratum is represented by one or more plant species when ranked in descending order of abundance (i.e., from most to least abundant). 63 ------- £) Sum the cover values for the ranked plant species beginning with the most abundant until the dominance threshold number is immediately exceeded; these species contributing to surpassing the threshold number are considered dominants, plus any additional species representing 20 percent or more of the total cover of the stratum; denote dominant species with an asterisk on the appropriate data form. F) Designate the indicator status of each dominant. 2) Bryophyte stratum (mosses, horned liverworts, and true liverworts): Bryophytes may be sampled as a separate stratum in certain wetlands, such as shrub bogs, moss-lichen wetlands, and the wetter wooded swamps, where they are abundant and represent an important component of the plant community. If treated as a separate stratum, follow the same procedures as listed for herb stratum. In many wetlands, however, bryophytes are not abundant and should be included as part of the herb stratum. 3} Shrub stratum (woody plants usually between 3 and 20 feet tall, including multi-stemmed, bushy shrubs and small trees below 20 feet): A) Determine the percent areal cover of shrub species within the entire plot by walking through the plot, listing all shrub species and estimating the percent areal cover of each species. B) Indicate the appropriate cover class (T and 1 through 7) and its corresponding midpoints (shown in parentheses) for each species: T - <1% cover (None); 1 - 1-5% (3.0); 2 = 6-15% (10.5); 3 - 16-25% (20.5); 4 - 26-50% (38.0); 5 - 51-75% (63.0); 6 - 76-95% (85.5); 7 • 96-100% (98.0). C) Rank shrub species according to their midpoints, from highest to lowest midpoint; D) Sum the midpoint values of all shrub species. E) Determine the dominance threshold number - the number at which 50 percent of the total dominance measure (i.e., cover class midpoints) for the stratum is represented by one or more plant species when ranked in descending order. F) Sum the midpoint values for the ranked shrub species, beginning with the most abundant, until the dominance threshold number is immediately exceeded; these species are considered dominants, plus any additional species representing 20 percent or more of the total midpoint values of the stratum; identify dominant species (e.g., with an asterisk) on the appropriate data form. 64 ------- 6) Designate the indicator status of each dominant. 4} Sapling stratum (young or small trees greater than or equal to 20" feet tall and with a diameter at breast height less than 5 inches): Follow the same procedures as listed for the shrub stratum or the tree stratum (i.e., plot sampling technique), whichever is preferred. 5) Woody vine stratum (climbing or twining woody plants): Follow the same procedures as listed for the shrub stratum. 6) Tree stratum (woody plants greater than or equal to 20 feet tall and with a diameter at breast height equal to or greater than 5 inches): Determine the basal area of the trees by individual and by species within the 30-foot radius sample plot. Basal area for individual trees can be calculated by measuring diameter at breast height (dbh) with a diameter tape and converting diameter to basal area using the formula A - £d2/4 (where A - basal area, jj « 3.1416, and d * dbh). Do the following steps: A) Locate and mark, if necessary, a sample unit (plot) with a radius of 30 feet, or change the shape of the plot to match topography, or increase size of plot based on species area curve assessment. fNotc; A larger sampling unit may be required when trees are large and widely spaced.) B) Identify each tree within the plot, measure its dbh (using a diameter tape), compute its basal area, then record data on the data form. (fiflifi: Compute basal area using the formula A = fid2/4, where A - basal area, fi - 3.1416, and d - dbh. To expedite this calculation, use a hand calculator into which the following conversion factor is stored * 0.005454 for diameter data in inches or 0.78535 in feet. Basal area in square feet of an individual tree can be obtained by squaring the tree diameter and multiplying by the stored conversion factor.) C) Calculate the total basal area for each tree species by summing the basal area values of all individual trees of each species. D) Rank species according to their total basal area, in descending order from the largest basal area to the smallest. £} Calculate the total basal area value of all trees in the plot by summing the total basal area for all species. F) Determine the dominant trees species; dominant species are those species (when ranked in descending order and cumulatively totaled) that immediately exceed 50 percent of the total basal area value for the plot, plus any additional species comprising^ v 65 ------- 20 percent or more of the total basal area of the plot; record the dominant species on the appropriate data form. G) Designate the indicator status of each dominant (i.e., OBL, FACW, PAC, FACU, or UPL) . After determining the dominants for each stratum, proceed to step 10. Step 10. Determine whether the hydrophytic vegetation criterion is met. When more than 50 percent of the dominant species in the sample plot have an indicator status of OBL, FACW, and/or FAC, hydrophytic vegetation is present. Complete the vegetation section of the summary data sheet. If the vegetation fails to be dominated by these types of species, the plot is usually not a wetland, however, it may constitute hydrophytic vegetation under certain circumstances (see disturbed areas discussion, on pp. 41, and the list of difficult-to-identify wetlands on pp. 31). If hydrophytic vegetation is present, proceed to Step 11. If the hydrophytic vegetation criterion is not met, then the area is nonwetland. Step 11. Determine whether the hydric soil criterion is met. Locate the observation area on a county soil survey map, if possible, and determine the soil map unit delineation for the area. Using a soil auger, probe, or spade, make a hole at least 18 inches deep at the representative location in each plant community type. Examine soil characteristics and compare if possible to soil descriptions in the county soil survey report or classify to Subgroup following "Soil Taxonomy" (often requires digging a deeper hole), or look for regional indicators of significant soil saturation (Appendix ). If soil has been plowed or otherwise altered, which may have eliminated these indicators, proceed to the section on disturbed areas (p.41). Complete the soils section on the appropriate data sheet and proceed to Step 9 if conditions satisfy the hydric soil criterion. Areas having soils that do not meet the hydric soil criterion are nonwetlands. (CAUTION: Become familiar with hydric soils that do not possess good hydric field indicators, such as red parent material soils, some sandy soils, and some floodplain soils, so that these hydric soils are not misidentified as nonhydric soils; see the difficult-to-identify wetlands discussion on p. 31.) Step 12. Determine whether the wetland hydrology criterion is met. Record observations and complete the hydrology section on the appropriate data form. If the wetland hydrolgy criterion is met, proceed to Step 13. If the wetland hydrology criterion is not met, the area is nonwetland. (CAUTION: Seasonally saturated wetland may not appear to meet the hydrology criterion at certain times of the growing season; see discussion of difficult-to-identify wetlands, page 31). Step 13. Make the wetland determination for the sample plot. Examine the data forms for the plot. When the plot meets the 66 ------- hydrophytic vegetation, hydric soil, and wetland hydrology criteria, it is considered wetland. Complete the summary data sheet; proceed to Step 14 when continuing to sample transects, or to Step 15 when determining a boundary between wetland and nonwetland sample plots. (Note: Double check all data sheets to ensure that they are completed properly before going to another plot.) Step 14. Take other samples along the transect. Repeat Steps 5 through 13, as appropriate. When sampling is completed for this transect proceed to Step 15. Step 15. Determine the wetland-nonwetland boundary point along the transect. When the transect contains both wetland and nonwetland plots, then a boundary must be established. Proceed along the transect from the wetland plot toward the nonwetland plot. Look for the occurrence of UPL and FACU species, the appearance of nonhydric soil types, subtle changes in hydrologic indicators, and/or slight changes in topography. When such features are noted, evaluate the three criteria and locate the wetland-nonwetland boundary (i.e., the point at which one of the three wetland hydrology criterion is no longer met; make sure, however, that this area does not qualify as a problem area wetland.). Establish new sample plots on each side of the boundary (e.g., within 50 feet) and repeat Steps 8 through 12. If existing plots are within a reasonable distance of the boundary, additional plots may not be necessary, but always document the features that were used to identify the boundary. Data sheets be completed for each plot. Mark the position of the wetland boundary point on the base map or photo and place a surveyor flag or stake at the boundary point in the field, as necessary. Continue along the transect until the boundary points between all wetland and nonwetland plots have been established. (CAUTION: In areas with a high interspersion of wetland and nonwetland plant communities, several boundary determinations will be required.) When all wetland determinations along this transect have been completed, proceed to Step 16. Step 16. Sample other transects and make wetland determinations along each. Repeat Steps 5 through 15 for each remaining transect. When wetland boundary points for all transects have been established, proceed to Step 17. Step 17. Determine the wetland-nonwetland boundary for the entire project area. Examine all completed copies of the data sheets and mark the location of each plot on the base map or photo. Identify each plot as either wetland (W) or nonwetland (N) on the map or photo. If all plots are wetlands, then the entire project area is wetland. If all plots are nonwetlands, then the entire project area is nonwetland. If both wetland and nonwetland plots are present, identify the boundary points on the base map or on the ground, and connect these points on the map by generally following contour lines to separate wetlands from nonwetlands. Confirm this boundary on the ground by walking the contour lines between the ^ A 67 ------- transects. Should anomalies be encountered, it will be necessary to establish short transects in these areas to refine the boundary, apply Step 15, and make any necessary adjustments to the boundary on the base map and/or on the ground. It may be worthwhile to place surveyor flags or stakes at these boundary points, especially when marking the boundary for subsequent surveying by engineers. Point Intercept Sampling Procedure The point intercept sampling procedure is a frequency analysis of vegetation used in areas that may meet the hydric soil and wetland hydrology criteria. It involves first identifying areas that may meet the hydric soil and wetland hydrology criteria within the area of concern and then refining the boundaries of areas that may meet the hydric soil criterion for further examination. Transects are then established for analyzing vegetation and determining whether hydrophytic vegetation criterion is met by calculating a prevalence index. Sample worksheets and a sample problem using this method are presented in Appendices . respectively. Step 1. Identify the approximate limits of areas that may meet the hydric soil criterion within the area of concern and sketch limits on an aerial photograph. To help identify these limits use sources of information such as Agricultural Stabilization and Conservation Service slides, soil surveys, NWI maps, and other maps and photographs. (Note: This step is more convenient to perform offsite, but may be done onsite; some modification of study area lines may be required after seeing the site in the field}. Areas that may meet the hydric soil criterion should be stratified into areas of similar soils and similar vegetation lifeforms (e.g., forested wetland, shrub wetland, and emergent wetland) for further analysis. Proceed to Step 2. Step 2. Scan the areas that may meet the hydric soil criterion and determine if disturbed conditions exist. Are any significantly disturbed areas present? If YES, identify their limits for they should be evaluated separately for wetland determination purposes (usually after evaluating undisturbed areas). Refer to the section on disturbed areas (p.41), if necessary, to evaluate the altered characteristic(s) (vegetation, soils, or hydrology), then return to this method and continue evaluating characteristics not altered. (Note: Prior experience with disturbed sites may allow one to easily evaluate an altered characteristic, such as when vegetation is not present in a farmed wetland due to cultivation.) Keep in mind that if at any time during this determination one or more of these three characteristics is found to have been significantly altered, the disturbed area wetland determination procedures should be followed. If the area is not significantly disturbed, proceed to Step 3. Step 3. Scan the areas that may meet the hydric soil criterion and determine if obvious signs of wetland hydrology or hydric soil % 68 ------- are present. The wetland hydrology criterion is met for any area or portion thereof where, it is obvious or known that the area is frequently inundated or saturated to the surface during the growi season. If the above condition exists, the hydric soil criterion is presumed to be net for the subject area and the area is considered wetland. If necessary (e.g., for a regulatory jurisdiction delineation) , confirm the presence of readily identified hydric soil by examining the soil for appropriate properties and take note of dominant plants which should easily meet the hydrophytic vegetation criterion. If the area's hydrology has not been significantly modified and the soil is organic (Histosols, except Folists) or is mineral classified as Sulfaquents, Hydraquents, or Histic Subgroups of Aquic Suborders according to "Soil Taxonomy", then the area is also considered wetland. fNote; The hydrophytic vegetation criterion is presumed to be met under these conditions, since the wetland hydrology and hydric soil criteria are met, so vegetation may not need to be examined, except for regulatory purposes. Regardless, hydrophytic vegetation should be fairly obvious in these situations.) Areas lacking obvious indicators of wetland hydrology must be further examined, so proceed to step 4. Step 4. Refine the boundary of areas that meet the hydric soil criterion. Verify the presence of hydric soil within the appropriate map units by digging a number of holes at least 18 inches deep along the boundary (interface) between hydric soil units and nonhydric soil units. Compare soil samples with descriptions in the soil survey report to see if they are properly mapped, and look for soi properties caused by wetland hydrology (see Appendix _ ). In this way, the boundary of areas meeting the hydric soil criterion is further refined by field observations. In map units where only part of the unit is hydric (e.g., complexes, associations, and inclusions) , locate hydric soil areas on the ground by considering landscape position and evaluating soil characteristics of the hydric soil portion or for properties caused by wetland hydrology. fNote; Some hydric soils, especially organic soils, have not been given a series name and are referred to by common names, such as peat, muck, swamp, marsh, wet alluvial land, tidal marsh, Sulfaquents, and Sulfihemists; these areas are also considered hydric soil map units and should appear on the county lists of hydric soil map units. Certain hydric soils are mapped with nonhydric soils as an association or complex, while other hydric soils occur as inclusions in nonhydric soil map units. Only the hydric soil portion of these map units should be evaluated for hydrophytic vegetation.) In areas where hydric soils are not easily located by landscape position and soil characteristics (morphology) , a soil scientist should be consulted. (CAUTION: Become familiar with hydric soils that do not possess good hydric field indicators, such as red parent material soils, some sandy soils, and some floodplains soils, so that these hydric soils are not misidentified as nonhydric soils, see section on difficult-to-identify wetlands, p. 31.) (Note; If the project area does not have a soil map, hydric soil areas must be determined in the field to use the point intercept sampling method. Consider 69 ------- landscape position, such as depressions, drainageways, floodplains, and seepage slopes, and either classify the soil or look for field indicators of hydric soil, then delineate the hydric soil areas accordingly. If the boundary of the hydric soil area cannot be readily delineated, one should use the quadrat sampling procedure (page ) After establishing the boundary of the area in question, proceed to Step 5. Step 5. Consider the following: 1) Is the area presently lacking hydrophytic vegetation or hydrologic indicators due to annual, seasonal, or long-term fluctuations in precipitation, surface water, or ground water levels? 2) Are hydrophytic vegetation indicators lacking due to seasonal fluctuations in temperature (e.g., seasonality of plant growth)? If the answer to either of these questions is YES or uncertain, proceed to the section on problem area wetland determinations (p. ). If the answer to both questions is NO, normal conditions are assumed to be present. Proceed to Step 6. (Note: In some cases, normal climatic conditions, such as snow cover or frozen soils, may prevent an accurate assessment of the wetland criteria; one must use best professional judgement to determine if delaying the wetland delineation is appropriate.) Step 6. Determine random starting points and random directions for three 200-foot line transects in each area that meets or nay meet the hydric soil criterion. (Note; More than three transects may be required depending on the standard error obtained for the three transects.) There are many ways to determine random starting points and random transect direction. The following procedures are suggested: 1) Starting point - Starting points for the transects are selected randomly along the perimeter of the area to be examined. Determine the approximate perimeter length and select three random numbers (from a table for generating random numbers or other suitable method); these random numbers indicate the position of the starting points for the three transects; pick a point along the perimeter to begin pacing off the distance to the starting points. 2) Transect direction - At a starting point, spin a pencil or similar pointed object in the air and let it fall to the ground. The direction that the pencil is pointing indicates the direction of the transect. Proceed to Step 7. Step 7. Lay out the transect in the established direction. If 70 ------- the transect crossas the hydric soil boundary (into the nonhydric soil area), bend the line back into the hydric soil area by randomj selecting a new direction for the transect following the procedure suggested above, Mark the approximate location of the transect on a base nap or aerial photo. Proceed to Step 8. Step 8. Record plant data (e.g., species name, indicator group, and number of occurrences) at interval points along the transect. Only individual plants with stems located in the subject area (i.e., soil type) should be recorded. At the starting point and at each point on 2-foot intervals along the transect, record all individual plants that would intersect an imaginary vertical line extending through the point. Count each individual plant only once per sample point; each individual of a single species counts as a separate plant for the tally (e.g., three individuals of red maple count as three hits for red maple at that single point). If this imaginary line has no plants intersecting it (either above or below the sample point), record nothing. Identify each plant observed to species (or other taxonomic category if species cannot be identified), enter species name on the Prevalence Index Worksheet, and record all occurrences of each species along the transect. For each species listed, identify its indicator group from the appropriate regional list of plant species that occur in wetlands (i.e., OBL, FACW, FAC, FACU, and UPL; see pp. ). Plant species not recorded on the lists are assumed to be upland species. If no regional indicator status and only one national indicator status is assigned, apply the national indicator status to the species. If no regional indicator/ status is assigned and more than one national indicator status is assigned, do not use the species to calculate a prevalence index. If the plant species is on the list and no regional or national indicator status is assigned, do not use the species to calculate the prevalence index. For a transect to be valid for a prevalence calculation, at least 80 percent of the occurrences must be plants that have been identified and placed in an indicator group. Get help in plant identification if necessary. Unidentified plants or plants without indicator status are recorded but are not used to calculate the prevalence index. Proceed to Step 9. Step 9. Calculate the total frequency of occurrences for each species (or other taxonomic category), for each indicator group of plants, and for all plant species observed, and enter on the Prevalence Index Worksheet. The frequency of occurrences of a plant species equals the number of times it occurs at the sampling points along the transect.. Proceed to Step 10. 71 ------- Step 10. Calculate the prevalence index for the transect using the following formula: IFo + 2Ffv + 3Ff + 4Ffu + SFu Pli - , Fo + Ffw + Ff + Ffu + Fu where Pli * Prevalence Index for transect i; Fo - Frequency of occurrence of obligate wetland (OBL) species; Ffw * Frequency of occurrence of facultative wetland (FACW) species; Ff - Frequency of occurrence of facultative (FAC) species; Ffu - Frequency of occurrence of facultative upland (FACU) species; Fu - Frequency of occurrence of upland (UPL) species. After calculating and recording the prevalence index for this transect, proceed to Step 11. Step 11. Repeat Steps 5 through 10 for two other transects. After completing the three transects, proceed to Step 12. Step 12. Calculate a mean prevalence index for the three transects. To be considered wetland, a hydric soil area usually must have a mean prevalence index (PIM) of less than 3.0. A minimum of three transects are required in each delineated area of hydric soil, but enough transects are required so that the standard error for PIM does not exceed 0.20 percent. Compute the mean prevalence index for the three transects by using the following formula: PIM - PIT N where PIM - mean prevalence index for transects; PIT - sum of prevalence index values for all transects; N - total number of transects. After computing the mean prevalence index for the three transects, proceed to Step 13. Step 13. Calculate the standard deviation (s) for the prevalence index using the following formula: (PI1-PIM)2 + CPI2-PIMJ2 + (PI3-PIMJ2 N-l fNote; See formulas in Steps 8 and 10 for symbol definitions.) After performing this calculation, proceed to Step 14. 72 ------- St«p 14. Calculate the standard error (sx) of the mean prevalence index using the following formula: sx where s • standard deviation for the Prevalence Index N - total number of transects (Note: The sx cannot exceed 0.20. If sx exceeds 0.20, one or more additional transects are required. Repeat Steps 6 through 14, as necessary, for each additional transect.) When sx for all transects does not exceed 0.20, proceed to Step 15. Step 15. Record final mean prevalence index value for each hydric soil map unit and make a wetland determination. All areas having a mean prevalence index of less than 3.0 meet the hydrophytic vegetation criterion (see p. 18). If the community has a prevalence index equal to or greater than 3.0, it is usually not hydrophytic vegetation except under certain circumstances; consult the section on difficult-to-identify wetlands (p.31) for these exceptions. Proceed to Step 16. Step 16. Determine whether the wetland hydrology criterion is met. Record observations and complete the hydrology section on the appropriate data form. If the wetland hydrolgy criterion is met, then the area is considered a wetland. If the area has been hydrologically disturbed, one must determine whether the area is effectively drained before making a wetland determination; this type of area should have been identified in Step 2 (see disturbed areas discussion, page 41). If the area is effectively drained, it is considered nonwetlartd; if it is not, the wetland hydrology driterion is met and the area is considered a wetland. (CAUTION: Seasonally saturated wetland may not appear to meet the hydrology criterion at certain times of the growing season; see discussion of difficult-to- identify wetlands, page 31). Step 17. Delineate the wetland boundary. After identifying the wetland, delineate the boundary by refining the limits of the area that meets the all three criteria (including any problem area wetlands). Mark the boundaries with flagging tape, if necessary. 73 ------- APPENDIX 5. Descriptions of Difficult-to-Identify Wetlands. Prairie Potholes. Potholes are glacially-formed depressions that are capable of storing water (Eisenlohr 1972). They are generally located in the north central United States and southern Canada. Although potholes nay occur in forested areas, the majority occur in the prairie region where they are subject to arid or semi-arid climatic conditions. Most potholes are small, generally less than an acre in size. Pothole soils are generally poorly drained, slowly permeable soils capable of ponding water. Precipitation is the basic source of water in potholes. Runoff from the drainage area is highly variable, but it is the key in determining if and how long ponding will occur. Precipitation in the pothole region varies appreciably from year to year. Average precipitation is far too small to meet the demands of evaporation and as a result most potholes are dry for a significant portion of the year, containing water for only a short period generally early in the growing season. In years of drought, potholes may not pond water at all. However in most years, seasonal replenishment can be expected (Eisenlohr 1972). In certain areas, the vast majority of potholes are farmed, either occasionally or every year, depending upon the duration of ponding. Many potholes have been either partially or totally drained to enhance agricultural production. The drastically fluctuating climate and alteration for farming have resulted in highly disturbed conditions that make wetland identification difficult. Aerial photographs, ASCS compliance slides, and other offsite information that depict long-term conditions are often better indicators of wetland conditions than onsite indicators reflecting only a single point in time. Plant communities in potholes are usually disturbed, either naturally or due to farming, and many do not exhibit vegetation typical of more stable wetlands. The process of annual drying (drawdown) in potholes enables the invasion of FAC, FACU, or UPL plant species during dry periods which may persist into the wet seasons. Stewart and Kantrud (1971) have recognized this condition in describing vegetation phases in their classification of wetlands for the Prairie Pothole Region. The phases are as follows: For nohcropland areas: Drawdown bare soil phase. As surface water in the open water phase gradually recedes and disappears, expanses of bare mud flats, which often become dry, are exposed. Ordinarily, this phase is of short duration, but in * 74 ------- Plavas. intermittent-alkali zones and occasionally in the more saline deep marsh zones, it nay persist for considerable periods. Natural drawdown emergent phase. Undisturbed areas with emergent drawdown vegetation are considered to be in this phase. Thin growth is composed mostly of annual plants, including many forbs, that germinate on the exposed mud or bare soil of the drawdown bare soil phase. After the drawdown emergents become established, surface water is occasionally restored by heavy summer rains. Characteristic plant species of this phase include: Eleocharis acicularis (terrestrial form), Rumex maritimus, Kochia scoparia, Xanthium italicum, Chenopodium rubrun, and Senecio congestus. For cropland area1 Cropland drawdown ase. Tilled pothole bottoms with drawdown vegetatii characterize this phase. The plants include many coarse, introduced annual weeds and grasses that normally develop on exposed mud flats during the growing season. These species appear as overwinter emergents whenever surface water is restored by summer rains. Characteristic plant species include: Agropyron repens, Echinochloa crusgalli, Polygonum lapathifolium, Veronica peregrina, Hordeum jubatum, Plagiobothrys scopulorum, Xanthium italicum, Bidens frondosa, Seteria glauca, Polygonum convolvulus, Agropyron smithii, Brassica kaber, Descruainia sophia, Androsace occidentalis, Ellisia nyctelea, Erigeron canadensis, and Iva xanthifolia. Cropland' tillage phase. In this phase, tilled bottom soils are dominated by annual field weeds, characteristic of fallow or neglected low cropland. Tilled dry pothole bottoms devoid of vegetation are also considered to be in this phase. Planted small grain or row crops are often present. Playas occur in many arid or semiarid regions of the world. Although occurring throughout much of the western United States, they are concentrated in the southern Great Plains as either ephemeral or permanent lakes or wetlands (Nelson et. al. 1983) . The topography of most playa regions is flat to gently rolling and generally devoid of drainage. Runoff from the surrounding terrain is collected into playa basins, where water is evaporated rapidly. Playas range in size from several hundred acres to only a few acres, with the majority being less than 10 acres. 75 ------- Surface soils of playas are generally clays that form a highly impermeable seal and increase their water-holding capacity. The playa soils are typically Vertisols. In the southern Great Plains, playa soils are listed as Randall, Lipan, or Ness clays, Stegall silty clay loams, Lofton clay loams, or may be uncharacterized occurring as inclusions within nonhydric soil map units. Soils of playas are generally distinguishable from surrounding upland soils because of their contrasting darker color (Reed 1930}. The hydrology of playas involves rapid accumulation of natural runoff during late spring, with a gradual loss by evaporation and seepage through the summer except where basins have been excavated to concentrate water. The hydrology is influenced by agricultural practices, including basin modification for water collection and retention and grazing in the watershed. Water reaching the playa is derived primarily from precipitation and runoff within the basin watershed. Playa basins are dry most of the time. The basins collect water primarily in two peak periods - May and September -as a result of regional convectional storms common throughout the region. Water collection in the basins is generally representative of seasonal or long-term extremes and not average annual conditions. As a result, wetland hydrology is best characterized by examining hydrological indicators over a multi-year period rather than relying on hydrological conditions that may be present at any point in time. The hydrology of most playa wetlands seldom allows a stable flora to develop. Playa basins may have a dense cover of annual or perennial vegetation or may be barren, depending on the timing, intensity and amount of precipitation and irrigation runoff, the extent of grazing, and the size of the playas. As with potholes, the process of annual drying (drawdown) in playas enables the invasion of FAC, FACU, and UPL plants during dry periods which may persist into other seasons. Playa basins may show vegetative zonation in concentric bands from the basin center to the perimeter in response to decreasing water depths or soil moisture levels. However, such zonation is not typical of all playa basins; small playas that collect limited runoff may support prairie vegetation (primarily FACU and UPL species} or may be cultivated. Cultivated basins often contain either the living plants or remnants of smartweeds (Polygonum spp.), ragweeds (Ambrosia spp.), or other invading annuals. Some playa basins are large enough to have an open expanse of deep water that may support aquatic plant communities. Vernal Pools. Vernal pools are depressional areas covered by shallow water for variable periods from winter to spring, but may be % 76 ------- completely dry for most of the summer and fall. Small pools may drain completely several times during the rainy season a some pools may not retain any water during drought years. An understanding of the natural history of the plants that occur in the transitional areas from pool to typically terrestrial habitat is useful in delineating these wetlands. Zedler (1987) provides an excellent overview of vernal pools which is briefly summarized below. Vernal pools are wide-ranging in size (from 10 feet wide to 10 acres) but are always shallow (less than 6 inches to 2 feet deep). Depth and duration of saturation and inundation are more important in defining a vernal pool than size. Soils with confining layers, either nearly impermeable clay layers or iron-silica cemented hardpans, often have a seasonally perched water table which favors the development of vernal pool. Microrelief on the soils typically is hummocky, with pits (depressions) and mounds. Individual vernal pools are often interconnected by a series of swales and tributaries, winter rainfall perches on the confining layer, until removed by evapotranspiration in the spring. A cemented hardpan or nearly impermeable clay subsoil layer, the pit and mound microrelief, and presence of swales are strong indicators of vernal pools. Vernal pools hold water long enough to allow some strictly aquatic organisms to grow and reproduce (complete their life cycles), but not long enough to permit the development of a typical pond or marsh ecosystem. Changes in a vernal pool during the season are so dramatic that it is in some ways more appropriate to consider it to be sequence of ecosystem (a cyclical wetland) rather than a single static type. Vernal pool development can be broken into four phases: (l) wetting phase, (2) aquatic phase, (3) drying phase, and (4) drought phase. The first rains stimulate the germination of dormant seeds and the growth of perennial plants (wetting phase). When the cumulative rainfall is sufficient to saturate the soils, aquatic plants and animals proliferate (aquatic phase). Nonaquatic plants are subjected to stress at this time. As the pool levels begin to recede (drying phase), the high soil moisture insures that plant growth continues after standing water is gone. Eventually, the plants succumb to drought and turn brown, with drying cracks appearing in the soil (drought phase). Plant species characteristic of vernal pools are endemic to vernal pools, or occur in vernal pools but are common in other aquatic habitats or associated with vernal pools (see Tables 6A-D in Zedler, 1987). Non-pool species can tolerate the limited periods of standing water that exist toward the pool margins. 77 ------- Since vernal pools typically vary considerably in depth and duration or both from year to year, within a year, or between different pools, plant composition is quite dynamic. FAC, FACU and UPL species often invade the pool basins in dry years, as they do in .other seasonally variable wetlands. Lack of hydrophytic plant species also nay be indicative of recent disturbances such as off-road vehicle activities, farming, or grazing. In delineating these wetlands, it is important to be aware not only of the "pool" but of the vernal pool complex (pool, basin, swales, tributaries), parts of which may have shorter and more variable periods of inundation. • Other Seasonally Variable Wetlands. In many regions (especially in arid and semiarid regions and areas with distinct wet and dry seasons), depressional areas occur that may have evidence of all three wetland criteria during the wetter portion of the growing season, but normally lack evidence of wetland hydrology and/or hydrophytic vegetation during the drier portion of the growing season. In addition, some of these areas lack hydric soil properties. Seasonal changes in plant species dominance may create problems for recognizing these wet during dry periods. While OBL and FACW plant species are normallly dominant during the wetter portion of the growing season, FACU and UPL species (usually annuals) may be dominant during the drier portion of the growing season and during and for some time after droughts. Examples of seasonally variable wetlands are pothole wetlands in the upper Midwest, playa wetlands in the Southwest, and vernal pools along the West Coast; these are discussed above. Become familiar with the ecology of these and similar types of wetlands (see Appendix for readings). Also, be particularly aware of drought conditions that permit invasion of UPL species (even perennials). Vegetated River Bars and Adjacent Flats. Along western streams in arid and semiarid parts of the country, some river bars and flats may be vegetated by FACU species while others may be colonized by wetter species. If these areas are frequently inundated and/or saturated sufficient to meet the wetland hydrology criterion, they are wetlands. They may be subject to flooding more than once during the growing season, depending on rainfall patterns. The soils often do not reflect the characteristic morphological properties of hydric soils, however, and thereby pose delineation problems. Difficult-to-Identify Wetland Situations Certain situations encountered in the field make wetland identification and delineation difficult. These situations are discussed below along with guidance on how to handle them. 78 ------- Navlv created wetlands. These wetlands include manmade (artificial wetlands, beaver-created wetlands, and other wetlands that have recently formed due to natural processes. Artificial wetlands may be purposely or accidentally created (e.g., road impoundments, undersized culverts, irrigation, and seepage from earth-dammed impoundments) by human activities. Many of these areas will have evidence of wetland hydrology and hydrophytic vegetation. The area should lack typical morphological properties of hydric soils, since the soils have just recently been inundated and/or saturated. Since all of these wetlands are newly established, evidence of one or more of the wetland identification criteria nay not be present. One must always consider the relative permanency of the wetter conditions. For example, if a beaver has recently blocked a road culvert that has now caused flooding of nonwetland (e.g., upland forest or field), it is quite possible that the blockage will soon be removed. In this case, the action is considered nonpermanent and the area is not considered wetland. If, however, hydrophytic vegetation has colonized the area, the hydrology is considered more or less permanently altered and the area is considered wetland. Temporary roads may impede the natural flow of water and impound water for some time. Yet, since the road is only temporary, the effect is also temporary, so the area is not considered wetland, unless, of course, it was wetland prior to the road construction. Wetlands on glacial till or in rockv areas. Sloping wetlands occur in glaciated areas where soils cover relatively impermeable glacial till or where layers of glacial till have different hydraulic conditions that permit groundwater seepage. Such areas are seldom, if ever, flooded, but downslope groundwater movement keeps the soils saturated for a sufficient portion of the growing season to produce anaerobic and reducing soil conditions. This promotes the development of hydric soils and hydrophytic vegetation. Evidence of wetland hydrology may be lacking during the drier portion of the growing season. Hydric soil properties also may be difficult to observe because certain areas are so rocky that it is difficult to examine soil characteristics within 18 inches. Wetland-nonwetland mosaics, in numerous areas, including northern glaciated regions and the coastal plain, the local topography may be pockmarked with a complex of "pits" (depressions) and "mounds" (knolls). The pits may. be wet enough to be classified as wetland, whereas the mounds are usually nonwetland. (Note: in some areas, the shallow mounds are also wetland. When this is true, the entire area is wetland.) The iriterspersion of wet pits and dry mounds may make the delineation of the wetland boundary difficult when the pits are too small to separate from the mounds. Of course, any area should be mapped within practical limits. When it is not practicable to separate the wet pits from the dry mounds, it is recommended that the wetland-nonwetland boundary be delineated by assessing the percent of the area covered by the wetland pits in an area of similar pit-mound relief. At least two random transects should be » 79 ------- established to determine the percent of pits vs. mounds. Based on the assessment at two-foot intervals along each transect, the percent of wetland vs. upland points can be established for the area. Consult the appropriate regulatory agency to learn what ratio they want to consider "wetland" for regulatory purposes. One should also note in his or her field report that this protocol was used and give an estimated size range for the wetland pits (e.g., 3-5* diameter) as well as a brief narrative description of the site. Cyclical wetlands. While the hydrology of all wetlands varies annually, the hydrology of certain wetlands may naturally fluctuate in a cyclical patterns of a series of consecutive wet years followed by a series of dry years. During the wet periods, hydrophytic vegetation and wetland hydrology are present, yet during the dry periods, the hydrology does not appear to meet the wetland hydrology criterion and FACU and UPL plant species often become established and may predominate under these temporal drier conditions. Despite the lack of periodic flooding or saturated soils for a multi-year period, these area should still be considered wetland, since in the long run, wetland characteristics prevail. Specific examples of cyclic wetlands include Alaska's black spruce-permafrost wetlands (see Alaska in regional list above), groundwater wetlands of the Cimmaron Terrace of Oklahoma and Kansas, and wetlands in coastal and West Texas (see Midwest regional list above). Other cyclical wetlands are associated with drought-prone areas such as southern California and the arid and semi-arid regions of the country. Vegetated Flats. Vegetated flats are characterized by a marked seasonal periodicity in plant growth. They are dominated by annual OBL species, such as wild rice (Zizania aquatica), and/or perennial OBL species, such as spatterdock (Nuphar luteum), that have nonpersistent vegetative parts (i.e., leaves and stems breakdown rapidly during the winter, providing no evidence of the plant on the wetland surface at the beginning of the next growing season). During winter and early spring, these areas lack vegetative cover and resemble mud flats; therefore, they do not appear to qualify as wetlands. But during the growing season the vegetation becomes increasingly evident, qualifying the area as wetland. In evaluating these areas, which occur both in coastal and interior parts of the country (e.g., regularly flooded freshwater tidal marshes and exposed shores of lakes or reservoirs during drawdowns due to natural fluctuations or human actions), one must consider the tine of year of the field observation and the seasonality of the vegetation. Again, one must become familiar with the ecology of these wetland types (see Appendix for readings). Interdunal swale wet;lands. Along the U.S. coastline, seasonally wet swales supporting hydrophytic vegetation are located within sand dune complexes on barrier islands and beaches. Some of these swales are inundated or saturated to the surface for considerable periods during the growing season, while others are wet for only the early » 80 ------- part of the season. In some cases, swales may be flooded irregularly by the tides. These wetlands have sandy soils that generally lack A evidence of hydric soil properties. In addition, evidence of wetlanW hydrology may be absent during the drier part of the growing season. Consequently, these wetlands may be difficult to identify. Springs and seepage wetlands. Wetlands occurring in flowing waters from springs and groundwater seepage areas may not exhibit typical hydric soil properties due to oxygen-enriched waters. Springs have permanently flowing waters, while seepage flows may be seasonal. Not all seepage areas, however, are considered wetlands. To qualify as wetland, the following conditions should be met: (1) 'seepage flow by oxygen-enriched waters is continuous for at least a 30-day period during the growing season in most years and saturate the soil to the surface, and (2) OBL and/or FACW species predominate or have a prevalence index less than or equal to 2.5. Soils wet for this duration are typically considered to have an aquic moisture regime and are hydric. The outer boundary of these wetlands is established by the limits of predominance of OBL and/or FACW species. Drought-affected Wetlands. Droughts periodically occur in many parts of the country, especially in the semiarid and arid West. During drought, it is quite obvious that water will not be observed in many wetlands, especially those higher up on the soil moisture gradient. With the drying of these wetlands over a number of consecutive years, environmental conditions no longer favor the growth of hydrophytic vegetation, so FACU and UPL species become established and often predominate in time. Thus, the plant community composition changes to one that is no longer dominated by hydrophytes. Such communities fail to meet the hydrophytic vegetation criterion, unless treated as problem area wetlands which is the case. Drought-affected wetlands should be identified by the presence of hydric soils, further refined by clear signs of long- term hydrology as'.expressed in the soil by: Thick organic surface layers, gleyed layers, low chroma matrices with high chroma mottles, and others listed as regional wetland hydrology indicators. Additional verification of hydrology may be advisable for some sites and an examination of aerial photographs during the wet part of the growing season in years of normal precipitation (distributions and amount) should reveal signs of wetland hydrology. In addition, landscape position (e.g., depressions and sloughs) may provide additional evidence for recognizing these wetlands during droughts. 81 ------- APPENDIX C. Difficult-To-Identify Hydric Soils Some hydric soils are soils lacking diagnostic hydric soil properties or soils that nay look like hydric soils in terns of soil color, but whose color is not the result of excess wetness. Presumably, the area in question has been located on a soil survey nap that identified it as a hydric component of a nap unit on the county list of hydric soil map units or if no maps are available, soil properties (matrix colors) that appear to contradict landscape position (e.g., red-colored soils in obvious depressions or gray- colored soils in obvious uplands) have been observed. Problem area soils are discussed in the following subsection. To determine whether the area in question is wetland, emphasis will be placed on vegetation and signs of hydrology, yet always consider landscape position in assessing the likelihood of wetland in these situations. Seven types of these hydric soils are recognized and discussed below. Hydric Entisols tfloodolain and sandv soils!. Entisols are usually young or recently formed soils that have little or no evidence of pedogenically developed horizons (U.S.D.A. Soil Survey Staff 1975). These soils are typical of floodplains throughout the U.S., but are also found in glacial outwash plains, along tidal waters, and in other areas. They include sandy soils of riverine islands, bars, and banks and finer-textured soils of floodplain terraces. Wet entisols have an aquic or peraquic moisture regime and are considered hydric soils, unless effectively drained. Some Entisols are easily recognized as hydric soils such as the Sulfaquents of tidal salt marshes and Hydraquents, whereas others pose problems because they do not possess typical hydric soil field indicators. Wet sandy Entisols (with loamy fine sand and coarser textures in horizons vithin 20 inches of the surface) may lack sufficient organic matter and clay to develop hydric soil colors. When these soils have a hue between 10YR and 10Y and distinct or prominent mottles present, a chroma of 3 or less is permitted to identify the soil as hydric (i.e., an aquic moisture regime). Also, hydrologic data showing that the soil is flooded or ponded enough to be wetland are sufficient to verify these soils as hydric. Sandy Entisols must have positive indicators of hydrology (see positive indicators for sandy soils for your region) in the upper 6 inches and have colors of the loamy fine sand or coarser Aquents. Soils that key to the aerie suborder or have colors of the aerie suborder within 12 inches are not considered hydric soils. Other Entisols are considered hydric if they classify in the aquic suborder and have the colors as listed for soils that are finer than loamy fine sand in some or all layers to a depth of 12 inches. Soils that key to the aerie subgroup or have aerie colors above 12 inches as listed for Aquent subgroups are not hydric. 82 ------- Hydric Mollisols fppairie and steppe soils!. Mollisols are dark colored, base-rich soils. They are common in the central part of the conterminous U.S. from eastern Illinois to Montana and south to Texas. Natural vegetation is mainly tall and mid grass prairies and short grass steppes. These soils typically have deep, dark-colored surface (mollic epipedons) and subsurface layers that have color values of less than 4 moist and commonly have chromas of 2 or less. The low chroma colors of Mollisols are not necessarily due to wetness of periods of saturation. They are rich in organic matter due largely to the vegetation (deep roots) and reworking of the soil and organic matter by earthworms, ants, moles, and rodents. The low chroma colors of Mollisols are not necessarily due to prolonged saturation, so be particularly careful in making wetland determinations in these soils. Many Great Groups of aquic Mollisols do not have aerie subgroups. Therefore, if a Mollisol is classified as an Aguoll, special care is needed to determine if it is hydric. There are two suborders of Mollisols that have aquic moisture regimes: Albolls and Aquolls. Albolls have an albic horizon that separates the surface layer from an argillie or natric horizon. The albic horizon must have chromas of 2 or less or the albic, argillic, or natric horizons must have characteristics associated with wetness such as mottles, iron-manganese concretions larger than 2 mm or both. All Albolls are considered hydric soils. Aquolls exhibiting regional hydrology characteristics for Mollisols in the upper part are considered hydric. Hydric Oxisols. These soils are highly weathered, reddish, yellowish, or grayish soils of tropical and subtropical regions. They are mixtures of quartz, kaolin, free oxides, and organic matter. For the most part, they are nearly featureless soils without clearly distinguishable horizons. Oxisols normally occur on stable surfaces and weathering has proceeded to great depths. To be hydric, these normally red-colored soils are required to have chromas 2 or less immediately below the surface layer, or if there are distinct or prominent mottles, the chroma is 3 or less. They also qualify as hydric if they have continuous plinthite within 12 inches of the surface. Hydric Spodosols (evergreen forest soils!. These soils, usually associated with coniferous forests, are common in northern temperate and boreal regions of the U.S. and along the Gulf-Atlantic Coastal Plain. Spodosols have a gray eluvial E-horizon overlying a diagnostic spodic horizon of accumulated (sometimes weakly cemented) organic matter, aluminum, and iron (U.S.D.A. Soil Survey staff 1975). A process called podzolization is responsible for creating these two soil layers. Organic acids from the leaf litter on the soil surface are moved downward through the soil with rainfall, cleaning the sand grains in the first horizon (the E-horizon) then coating the sand grains with organic matter and iron oxides in the second layer (the spodic horizon). Certain vegetation produce organic acids that speed podzolization including eastern hemlock 83 ------- (Tsuga canadensis), spruces (Picea spp.), pine (Pinus spp.), larches (Larix spp.)/ and oaks (Quercus spp.) (Buol, et al. 1980). The E- horizon or Albic horizon by definition has a chroma of 3 or less and is often mistaken for a gleyed layer by the novice. These Spodosols must have one of the positive regional hydrology indicators and meet the color requirement for Aguods listed in "Soil Taxonomy." Hydric Spodosols that have a thick (more than 12 inches) sandy epipedon are extremely difficult to identify especially in the Gulf-Atlantic Coastal Plain. These soils must also meet the color requirements for the Aguod suborder and meet one of the regional hydrology indicators for sandy soils. Hvdric Vertisols (shrink and swell soils). These soils are dark- colored clayey soils that are extensive in the Great Plains, in the southern U.S., and in parts of California. They develop wide, deep cracks when dry and swell shut, when wet. Many Vertisols exhibit gilgai microtopography with swells and swales or mounds and hollows. The morphology of these soils may be distinctly different on the mound and in the hollow. They commonly have thick dark-colored surface layers because of the churning action created by the shrinking and swelling clays. During wet periods, they are very slowly permeable and may pond water on the surface of the micro- hollows, but in dry periods they are rapidly permeable with water travelling along the deep cracks to lower layers. These soils must meet one of the regional hydrology indicators for Vertisols to qualify as hydric. Hydric soils derived from red parent material. Hydric mineral soils derived from red parent materials (e.g., weathered clays, Triassic sandstones, and Triassic shales) may lack the low chroma colors characteristic of most hydric mineral soils. In these soils, the hue is redder than 10YR because of parent materials that remain red after citrate-dithionite extraction, so the low chroma requirement for hydric soil is waived (U.S.O.A. Soil Conservation Service 1982). Red soils are most common along the Gulf-Atlantic Coastal Plain (Ultisols), but are also found in the Midwest and parts of the Southwest and West (Alfisols), in the tropics, and in glacial areas where older landscapes of red shales and sandstones have been exposed. In southern New England, red parent material hydric soils are derived from reddish sandstone, shale, conglomerate, or basalt. These soils include the following series: Meno (Aerie Haplaquepts), Wilbraham (Aquic Dystrochrepts), Lim (Aerie Fluvaquents), and Bash (Fluvaquentic Dystrochrepts). In the absence of diagnostic hydric soil properties, more weight must be placed on the vegetation and hydrology. Follow procedures for identifying wetlands in problem area soils at the beginning of this subsection. Hydric soils derived from low chroma parent materials. Soils derived from slate and phyllite produce low chroma colors due to this parent material. In southern New England, nonhydric soils having I predominantly low chroma colors include the following series: I 84 ------- Newport, Nassau, Dutches*, Bernards ton, Pittstown, Dummerston, Taconic, Macomber, Lakesboro, and Fullan. A few series derived from/ these materials are hydric, including Stissing, Brayton, and Mansfield, with the first two including nonhydric members as well. Due to the difficulty of using soil colors as indicators of wetness, more weight must be placed on vegetation and hydrology. Follow procedures for identifying wetlands in problem area soils at the beginning of this subsection. 85 ------- APPENDIX 7. Procedures for Difficult-to-Identify Wetlands Difficult-to-identify wetlands are to be identified using the procedures below. These procedures should only be used in accordance with the guidance for difficult-to-identify wetlands on Page 31. 1. What is the reason for the difficulty in wetland identification/delineation? (Identify only one of the parameters as the basis for this difficulty): If vegetation is the criterion for which a positive indicator was not identifiable, go to 2a. If soils, go to 2b. If hydrology, go to 2c. 2a. Is the plant community growing on a soil that meets the hydric soil criterion on page 22? If no, the area is non-wetland. If yes, document the reasons for this conclusion and go to 3a. 3a. Are one or more of the following conditions satisfied?: * hydrologic records or aerial photography combined with hydrologic records (items l and 2 on page 11) document wetland hydrology; or * one or more primary hydrologic indicators (item 3 on page 11) is documented to have been found at the site; or * one or more secondary hydrologic indicators are materially present and supported by corroborative information as described in item 4 on page 12 (e.g., regional indicators of saturation, hydrologic gauge data, NWI maps). If no, the area is non-wetland. If yes, the area is a wetland; document the reasons for this conclusion. The upper boundary of these wetlands is established by the limits of the combination of the wetland hydrology indicators present and hydric soil. 2b. Does the soil support a plant community that meets the hydrophytic vegetation criterion on page 18? % 86 ------- If no, th« area is non-wetland. If yes, document the reasons for this conclusion and go to 3b. 3b. Are one or more of the following conditions satisfied: * hydrologic records or aerial photography combined with hydrologic records (items 1 and 2 on page 11) document wetland hydrology; or * one or more primary hydrologic indicators (iten 3 on page 11) is documented; or * one or more secondary hydrologic indicators are materially present and supported by corroborative information as described in item 4 on page 12 (e.g., regional indicators of saturation, hydrologic gauge data, NWI naps)? If no, the area is non-wetland. If yes, the area is a wetland; document the reasons for this conclusion. The upper boundary of these wetlands is established by the limits of the combination of the wetland hydrology indicators present and hydrophytic vegetation. 2c. Is the plant community growing on a soil that meets the hydric soil criterion on page 22 ? If no, the area is non-wetland. If yes, document the reasons for this conclusion and go to 3c. 3c. Does the area demonstrate a regional indicator of saturation (see Appendix -) If no, go to 5c. If yes, go to 4c. 4c. Does the area support a plant community that meets the hydrophytic vegetation criterion on page 18 ? If no, the area is non-wetland. 87 ------- If yes, the area is a wetland. Document the reasons for this conclusion. The upper boundary of this wetland is established by the limits of the combination of hydrophytic vegetation, hydric soils, and the regional indicators of saturation present. 5c. Does the percent cover of obligate wetland (OBL) and facultative wetland (FACW) species in all strata except the tree stratum exceed that of the facultative upland (FACU) and upland (UPL) species in the all strata except the tree stratum or does the plant community have a mean prevalence index of less than 3.0? If no, the area is non-wetland. If yes, the area is wetland; document the reasons for this conclusion. The upper boundary of this wetland is established by the limits of the combination of the wetland vegetation as described in this step and hydric soils. 88 ------- APPENDIX t. Disturbed Area Procedures Step 1. Determine whether vegetation, soils, and/or hydrology have been significantly altered at the site. Proceed to Step 2, Step 2. Determine whether the "altered" characteristic met the wetland criterion in question prior to site alteration. Review existing information for the area (e.g., aerial photos, NWI maps, soil surveys, hydrologic data, and previous site inspection reports), contact knowledgeable persons familiar with the area, and conduct an onsite inspection to build supportive evidence. The strongest evidence involves considering all of the above plus evaluating a nearby reference site (an area similar to the one altered before modification) for field indicators of the three technical criteria for wetland. If a human activity or natural event altered the vegetation, proceed to Step 3; the soils, proceed to Step 4; the hydrology, proceed to Step 5. Step 3. Determine whether the hydrophytic vegetation criterion was met prior to disturbance: 1) Describe the type of alteration. Examine the area and describe the type of alteration that occurred. Look for evidence of selective harvesting, clearcutting, bulldozing, recent conversion to agriculture, or other activities (e.g., burning, discing, the presence of buildings, dams, levees, roads, and parking lots). 2) Determine the approximate date when the alteration occurred if necessary. Check aerial photographs, examine building permits, consult with local individuals, and review other possible sources of information. 3) Describe-the effects on the vegetation. Generally describe how the recent activities and events have affected the plant communities. Consider the following: A) Has all or a portion of the area been cleared of vegetation? B) Has only one layer of the plant community (e.g., trees) been removed? C) Has selective harvesting resulted in the removal of some species? D) Has the vegetation been burned, mowed, or heavily grazed? E) Has the vegetation been covered by fill, dredged material, or structures? F) Have increased water levels resulted in the death ^of 89 ------- all or some of the vegetation? 4) Determine whether the area had plant communities that met the hydrophytic vegetation criterion. Develop a list of species that previously occurred at the site from existing information, if possible, and determine whether the hydrophytic vegetation criterion was met. If site-specific data do not exist, then do the following, as appropriate: A) If the vegetation is removed and no other alterations are done, then the presence of hydric soils and evidence of wetland hydrology will be used to identify wetlands. If such evidence is found, conditions are assumed to be sufficient to support hydrophytic vegetation. It nay be advantageous to examine a nearby reference site to collect data on the plant community to confirm this assumption. (Note; Determination of regulatory jurisdiction for such areas is subject to agency interpretation. For example, Federal wetland regulatory policy under the Clean water Act, and agricultural program policy under the Food Security Act of 1985, as amended, interprets the relative permanence of disturbance to vegetation caused by cropping. Be sure to consult appropriate agency in making Federal wetland jurisdictional determinations in such areas.) B) If the area is filled, burying the vegetation, and no other alterations (i.e., to hydrology or soils) have taken place, then either: (1) look below the fill layer for hydric soil and indicators of wetland hydrology, plus any signs of hydrophytic vegetation (if not decomposed), or (2) if type of fill (e.g., concrete) precludes examination of soil beneath the fill, then review existing information (e.g., soil survey, wetland maps, and aerial photos) to determine if the area was wetland. If necessary, evaluate a neighboring undisturbed area (reference site) with characteristics (i.e., vegetation, soils, hydrology, and topography) similar to the area in question prior to its alteration. Be sure to record the location and major characteristics (vegetation, soils, hydrology, and topography) of the reference site. Sample the vegetation in this reference area using an appropriate onsite determination method to determine whether hydrophytic vegetation is present. If the hydrophytic vegetation criterion is met at the reference site, then this criterion is presumed to have been met in the altered area. If no indicators of hydrophytic vegetation are found at the reference site, then the original vegetation at the project area is not considered to have met the hydrophytic vegetation criterion. C) If soils and/or hydrology also have been disturbed, 90 ------- then continue Steps 4, 5, and 6 below, as necessary. Otherwise, return to the applicable step of the onsite determination method being used. Step 4. Determine whether or not hydric soils previously occurred: 1} Describe the type of alteration. Examine the area and describe the type of alteration that occurred. Look for evidence of: A) Deposition of dredged or fill material - In many cases the presence of fill material will be obvious. If so, it will be necessary to dig a hole to reach the original soil (sometimes several feet deep). Fill material will usually be a different color or texture than the original soil (except when fill material has been obtained from similar areas onsite). Look for decomposing vegetation between soil layers and the presence of buried organic or hydric mineral soil layers. In rare cases, excessive deposition of sediments may be due to catastrophic conditions, e.g., mud slides and volcanic eruptions. Floodplain environments are subjected to periodic sedimentation, but this is a more normal occurrence and does not constitute a significant disturbance for purposes of this manual. B) Presence of nonwoody debris at the surface - This can only be applied in areas where the original soils do not contain rocks. Nonwoody debris includes items such as rocks, bricks, and concrete fragments. C) Subsurface plowing - Has the area recently been plowed below the A-horizon or to depths of greater than 10 inches? ' D) Removal of surface layers - Has the surface soil layer been removed by scraping or natural landslides? Look for bare soil surfaces with exposed plant roots or scrape scars on the surface. E) Presence of manmade structures - Are buildings, dams, levees, roads,, or parking lots present? 2} Determine the approximate date when the alteration occurred, if necessary. Check aerial photographs, examine building permits, consult with local individuals, and review other possible sources of information. 3) Describe the effects on soils. Consider the following: A) Has the soil been buried? If so, record the depth of fill material and determine whether the original soil,was 91 ------- left intact or disturbed. (Note: The presence of a typical sequence of soil horizons or layers in the buried soil is an indication that the soil is still intact; check description in the soil survey report.) B) Has the soil been nixed at a depth below the A-horizon or greater than 12 inches? If so, it will be necessary to examine the soil at a depth immediately below the plow layer or disturbed zone. C) Has the soil been sufficiently altered to change the soil phase? Describe these changes. If a hydric soil has been drained to some extent, refer to Step 5 below to determine whether soil is effectively drained or is still hydric. 4) Characterize the soils that previously existed at the disturbed site. Obtain all possible evidence that may be used to characterize soils that previously occurred on the area. Consider the following potential sources of information: A) Soil surveys - In many cases, recent soil surveys are available. If so, determine the soils that were mapped for the area. If all soils are hydric soils, it is presumed that the entire area had hydric soils prior to alteration. Consult aerial photos to refine hydric soil boundaries, especially for soil nap units with hydric soil inclusions. B) Buried soils - When fill material has been placed over the original soil without physically disturbing the soil, examine and characterize the buried soils. Dig a hole through the fill material until the original soil is encountered. Determine the point at which the original soil material begins. Remove 18 inches of the original soil front the hole and follow standard procedures for determining whether the hydric soil criterion is met (see p. ). (Hfitfi: When the fill material is a thick layer, it might be necessary to use a backhoe or posthole digger to excavate the soil pit.) If USGS topographic maps indicate distinct variation in the area's topography, this procedure must be applied in each portion of the area that originally had a different surface elevation. C) Deeply plowed soils or removed surface layers - If soil surface layers are removed, redistributed or deeply plowed (excluding normal plowing), vegetation will not be present, so review existing information (e.g., soil surveys, wetland maps, and aerial photos), identify a nearby reference site that is similar to disturbed area prior to its alteration, evaluate for indicators of hydrophytic vegetation, hydric soils, and wetland hydrology and make wetland or nonwetland determination, as 92 ------- appropriate. 5} Determine whether hydric soils were present at the project area prior to alteration. Examine the available data and determine whether evidence of hydric soils were formerly present. If no evidence of hydric soils is found, the original soils are considered nonhydric soils. If evidence of hydric soils is found, the hydric soil criterion has been met. Continue to Step 5 if hydrology also was altered. Otherwise, record decision and return to the applicable step of the onsite determination method being used. Step 5. Determine whether wetland hydrology existed prior to alteration and whether wetland hydrology still exists (i.e., is the area effectively drained?). To determine whether wetland hydrology still occurs, proceed to Step 6. To determine whether wetland hydrology existed prior to the alteration: 1) Describe the type of alteration. Examine the area and describe the type of alteration that occurred. Look for evidence of: A) dams - Has recent construction of a dam or some natural event (e.g., beaver activity or landslide) caused the area to become increasingly wetter or drier? (Note: This activity could have occurred at a considerable distance from the site in question, so be aware of and consider the impacts of major dams in the watershed above the project area.) B) levees,, dikes, and similar structures - Have levees or dikes been recently constructed that prevent the area from periodic overbank flooding? C) ditches or drain tiles - Have ditches or drain tiles been recently constructed causing the area to drain more rapidly? D) channelization * Have feeder streams recently been channelized sufficiently to alter the frequency and/or duration of inundation? E) filling of channels and/or depressions (land-leveling) - Have natural channels or depressions been recently filled? F) diversion of water - Has an upstream drainage pattern been altered that results in water being diverted from the area? G) groundwater withdrawal - Has prolonged and intensive 93 ------- pumping of groundwater for irrigation or other purposes significantly lowered the water table and/or altered drainage patterns? 2) Determine the approximate date when the alteration occurred, if necessary. Check aerial photographs, consult with local individuals, and review other possible sources of information. 3) Describe the effects of the alteration on the area's hydrology. Consider the following and generally describe how the observed alteration affected the project area: A) Is the area more frequently or less frequently inundated than prior to alteration? To what degree and why? B) Is the duration of inundation and soil saturation different than prior to alteration? How much different and why? 4) Characterize the hydrology that previously existed at the area. Obtain and record all possible evidence that may be useful for characterizing the previous hydrology. Consider the following: A) stream or tidal gauge data - If a stream or tidal gauging station is located near the area, it may be possible to calculate elevations representing the upper limit of wetland hydrology based on duration of inundation. Consult SCS district offices, hydrologists from the local CE district offices or other agencies for assistance. If fill material has not been placed on the area, survey this elevation from the nearest USGS benchmark. If fill material has been placed on the area, compare the calculated elevation with elevations shown on a USGS topographic map or any other survey map that predates site alteration. B) field hydrologic indicators onsite or in a neighboring reference area - Certain field indicators of wetland hydrology may still be present. Look for water marks on trees or other structures, drift lines, and debris deposits (see pp. 17-19 for additional hydrology indicators). If adjacent undisturbed areas are in the same topographic position, have the same soils (check soil survey map), and are similarly influenced by the same sources of inundation, look for wetland hydrology indicators in these areas. C) aerial photographs - Examine aerial photographs and determine whether the area has been inundated or saturated % 94 ------- during the growing season. Consider the time of the year that the aerial photographs were taken and use only photographs taken prior to site alteration. D) historical records - Examine historical records for evidence that the area has been periodically inundated. Obtain copies of any such information. E) National Flood Insurance Agency flood maps - Determine the previous frequency of inundation of the area from national floods maps (if available). F) local government officials or other knowledgeable individuals - Contact individuals who might have knowledge that the area was periodically inundated or saturated. If sufficient data on hydrology that existed prior to site alteration are not available to determine whether wetland hydrology was previously present, then use the other wetland identification criteria (i.e., hydrophytic vegetation and hydric soils) to make a wetland determination. 5) Determine whether wetland hydrology previously occurred. Examine available data. If hydrology was significantly altered recently (e.g., since Clean Water Act), was wetland hydrology present prior to the alteration? If the vegetation and soils have not been disturbed, use site characteristics - vegetation, soils, and field evidence oJ wetland hydrology - to identify wetland. If vegetation and soil are removed, then review existing information (e.g., soil surveys, wetland maps, and aerial photos), following procedures in Step 6, substep 3. If no evidence of wetland hydrology is found, the original hydrology of the area is not considered to meet the wetland hydrology criterion. If evidence of wetland hydrology is found, the area used to meet the wetland hydrology criterion. Record decision and return to the applicable step of the onsite determination method being used. Step 6. Determine whether wetland hydrology still exists. Many wetlands have a single ditch running through them, while others may have an extensive network of ditches. A single ditch through a wetland nay not be sufficient to effectively drain it; in other words, the wetland hydrology criterion still may be met under these circumstances. Undoubtedly, when ditches or drain tiles are observed, questions as to the extent of drainage arise, especially if the ditches or drain tiles are part of a more elaborate stream channelization or other drainage project. In these cases and other situations where the hydrology of an area has been significantly altered (e.g., dams, levees, groundwater withdrawals, and water diversions), one must determine whether wetland hydrology still exists. If it is present, the area is not effectively drained. If 95 ------- wetland hydrology is not present, the area is not a wetland. To determine whether wetland hydrology still exists: 1) Describe the type or nature of the alteration. Look for evidence of: A) dans; B) levees, dikes, and similar structures; C) ditches; D) channelization; E) filling of channels and/or depressions; F) diversion of water; and G) groundwater withdrawal. (See Step 5 above for discussion of these factors.) 2) Determine the approximate date when the alteration occurred, if necessary. Check aerial photographs, consult with local officials, and review other possible sources of information. 3) Characterize the hydrology that presently exists at the area. When evaluating agricultural land to determine the presence or absence of wetland, it is recognized that such lands are generally disturbed and must be viewed in that context. Wetland hydrology is often altered on agricultural lands, so the mere presence of soils meeting the hydric soil criterion is not sufficient to determine that wetlands are present. Due to the common hydrologic and vegetative modifications on agricultural lands, indicators of wetland hydrology, together with soil-related properties, are the most reliable means of wetland identification. The following procedure is designed to provide technical guidance for determining whether an area subject to some degree of hydrologic modification still meets the wetland hydrology criterion. In general, the hydrology of most such areas can be evaluated by reviewing existing site-specific information, examining aerial photographs, or conducting onsite inspections to look for evidence of wetland hydrology (substeps A-F). More rigorous assessment (substep G) may be done less commonly where despite the lack of wetland hydrology evidence one has a strong suspicion that wetland hydrology still exists. The reason for doing this more detailed assessment should be documented. CAUTION: WHEN THE HYDROLOGY OF AN AREA HAS BEEN SIGNIFICANTLY ALTERED, SOIL CHARACTERISTICS RESULTING FROM WETLAND HYDROLOGY CANNOT BE USED TO VERIFY WETLAND HYDROLOGY SINCE THEY PERSIST AFTER WETLAND HYDROLOGY HAS BEEN ELIMINATED.) Figure shows the sequence of substeps required to evaluate whether the wetland hydrology criteria is net. A) Review existing site-specific hydrologic information to see if data support the wetland hydrology criterion. If such data are unavailable or inconclusive, proceed to step 2. B) Examine aerial photographs (preferably early spring or wet 96 ------- growing season) for several recent years (e.g., a minimum of 5 years is recommended), look for signs of inundation or prolonged soil saturation, and consider these observations in the context of long-term hydrology, fflqfre; Large-scale aerial photographs, 1:24,000 and larger, are preferred.) Be sure to Know the prevailing environmental conditions for all dates of photography. Try to avoid abnormally wet or dry dates for they may lead to erroneous conclusions about wetland hydrology. You are attempting to assess conditions during normal rainfall years. If the area is wet more years than not during normal rainfall years (e.g., 3 of 5 years or 6 or 10 years), then the wetland hydrology criterion is presumed to be met. If the area shows no indication of wetness during normal rainfall years or shows such signs in only a few years (e.g., 1 of 5 years or 3 of 10 years), then the wetland hydrology criterion is presumed not to be met. !Cf conditions are between the two mentioned above (e.g., 2 of 5 years or 4-5 of 10 years), proceed to substep C. mote: Only those areas showing signs of wetness should be considered to meet the wetland hydrology criterion.) C) Examine additional aerial photos, National Wetland Inventory maps/ or other information for indication of wetland or signs of wetland hydrology. If other information, coupled with the previous information is substep B, indicates that the area is wet more often than not (e.g., 3 of 5 years or 6 of 10 years), or indicates that the area is wet half of the time (e.g., 3 of 6 years or 5 of 10 years), then the wetland hydrology criterion, is presumed to be met. If other information, coupled with the previous information in substep 2, provides indication that the area is wet less often than not (e.g., 2 of 5 years or 4 of 1C years), then the wetland hydrology criterion is presumed not to be met. If it is perceived after reviewing additional information that wetland hydrology is still inconclusive, proceed to substep D. D) Inspect the «ite for direct evidence of inundation or prolonged soil saturation or other field evidence of wetland hydrology (excluding soil properties resulting from long-term hydrology) to determine whether the wetland hydrology criterion is met. Ideally, such inspection should be done during the early or wet part of the growing season during a normal rainfall year. Avoid periods after heavy rainfall or immediately after more normal rainfalls. After conducting the onsite inspection, if necessary, proceed to substep E in areas where vegetation has not been removed or cultivated or to substep G in cultivated areas to perform a more rigorous assessment of vegetation and/or hydrology and document your reason for doing so. E) Inspect the site, on the ground to assess changes in the plant community. If OBL or OBL and FACW plant species (especially in the herb stratum) are dominant or 97 ------- scattered throughout the site and UPL species are absent or not dominant, the area is considered to meet the wetland hydrology criterion and remains wetland. If UPL species predominate one or more strata (i.e., they represent more than 50 percent of the dominants in a given stratum) and no OBL species are present, then the area is considered effectively drained and is no longer wetland. (Note; Make sure that the UPL species are materially present and dominate a valid stratum, see p. ). If the vegetation differs from the above situations, then the vegetation at this site should be compared if possible with a nearby undisturbed reference area, so proceed to substep F; if it is not possible to evaluate a reference site and the area is ditched, channelized or tile-drained, go to substep G. F) Locate a nearby undisturbed reference site with vegetation, soils, hydrology, and topography similar to the subject area prior to its alteration, examine the vegetation (following an appropriate onsite delineation method), and compare it with the vegetation at the project site. If the vegetation is similar (i.e., has the same dominants or the subject area has different dominants with the same indicator status or wetter as the reference site), then the area is considered to be wetland — the wetland hydrology criterion is presumed to be satisfied, if the vegetation has changed to where FACU and UPL species or UPL species alone predominate and OBL species are absent, then the area is considered effectively drained and is nonwetlahd. If the vegetation is different than indicated above, additional work is required — go to substep 6. G) Select one of the following approaches to further assess the area's hydrology: (1) Determine the "zone of influence" of the drainage structure and its effect on the water table using existing SCS soil drainage guides, the ellipse equation, or similar drainage model (SCS soil drainage guides and the ellipse equation relate only to water table and do not address surface water), and determine the effect of the drainage structure on surface water (ponding and flooding). Factors to consider when analyzing the effect of the drainage structure on surface water are: (a) the type of drainage system (e.g., size, spacing, depth, grade, and outlet conditions); (b) surface inlets; (c) condition of the drainage system; (d) how surface water is removed; and (e) soil type as it related to ~ runoff. An example using the ellipse equation to calculate the zone of influence is given in Appendix l or, (2) Conduct detailed ground water studies, making direct observations of inundation and soils saturation 98 ------- throughout the area in question. Data should be collected in the following manner: (a) Depth of Wells. Well should be placed within 24 inches of the soil surface or to the top of the restrictive horizon, if shallower. (b) Annual Observation Period.. Observations should be made during the expected high water table period including both the nongrowing and growing seasons; the recommended period of observation will vary regionally. At a minimum, the period should encompass a three month period during the wettest part of the growing season and include the month before the start of the growing season if the wettest part is in the Spring. (c) Frequency of Observation. During the observation periods, the wells should be observed a minimum of two times per week at a regular interval not to exceed four days between observations; for soils with anticipated rapid fluctuations of the water table (e.g., sandy soils) , a one or two day observation interval is recommended . (d) Length of Study. A minimum of three observation periods, each having at least 90% of average yearly precipitation and at least 90% cf normal monthly distribution. Also, the year prior to the water table study must have had 90% of the monthly and annual precipitation. The observation study may cease after the minimum consecutive time period required for meeting the wetland hydrology criterion. fNote; Data from any year that does not have 90% of average precipitation cannot be counted toward the three-year study duration unless it can be adequately justified in a specific case.) Precipitation information should be locally derived (not necessarily site-specific) from the nearest NOAA-approved weather station or other available sources of technically valid information (e.g., university branch stations or research sites, media weather stations, uses stations, state agency stations, etc.). These precipitation stations must be located within 25 miles of the monitored water table study. If this is not possible, consult appropriate regulatory agency for alternatives. Appendix contains information on the installation of *^^^*™ 99 ------- delineating the wetland. ground-water observation wells. ^ 100 ------- ------- |