Federal Manual forIdentifying and Delineating

Jurisdictional Wetlandsv

"#«S

AN INTERAGENCY COOPERATIVE PUBLICATION

Fish andWildlife Service

Department ofthe Army

EnvironmentalProtection Agency

Soil ConservationService

January 1989EPA Region 5 Records Ctr.

233076

Federal Manual for Identifyingand Delineating

Jurisdictional Wetlands

An Interagency Cooperative Publication

U. S. Army Corps of Engineers U.S. Environmental Protection Agency

U.S. Fish and Wildlife Service U.S.D.A. Soil Conservation Service

JANUARY 10, 1989

Federal Manual for Identifyingand Delineating

Jurisdictional Wetlands

W

We, the undersigned, hereby adopt this Federal Manual as the technicalbasis for identifying and delineating Jurisdictional wetlands in theUnited States.

Frank DunkleDirectorFish and Wildlife Service

Rebecca HanmerActing Assistant Administrator for WaterEnvironmental Protection Agency

Robert W. PageAssistant Secretary of the Army(Civil Works)Department of Army

Wilson ScalingChiefSoil Conservation Service

January 10,1989I .S.

USH »WILHtRVHt

PrefaceThis manual describes technical criteria, field indicators and other sources of information, andmethods for identifying and delineating jurisdictional wetlands in the United States. This manu-

,/ \l al is the product of many years of practical experience in wetland identification and delineation\f/ by four Federal agencies: Army Corps of Engineers (CE), Environmental Protection Agency

(EPA), Fish and Wildlife Service (FWS), and Soil Conservation Service (SCS). It is the culmi-nation of efforts to merge existing field-tested wetland delineation manuals, methods, and pro-

cedures used by these agencies. This manual draws heavily upon published manuals and methods, specifi-cally Corps of Engineers Wetlands Delineation Manual, EPA's Wetland Identification and DelineationManual, and SCS's Food Security Act Manual wetland determination procedure.

The manual has been reviewed and concurred in by an interagency committee composed of the four Feder-al agencies. This committee was established for purposes of reconciling differences in wetland delineationprocedures and developing a single interagency manual for identification and delineation of wetlands. Thecommittee consisted of the following individuals: Robert Pierce, Bernie Goode, and Russell Theriot of theCorps of Engineers; John Meagher, Bill Sipple, and Charles Rhodes of the Environmental ProtectionAgency; David Stout, Ralph Tiner, and Bill Wilen of the Fish and Wildlife Service; and Steve Brady,Maurice Mausbach, and Billy Teels of the Soil Conservation Service. The manual was prepared by RalphTiner based on interagency committee decisions. The negotiations were facilitated by Howard Bellman andLeah Haygood.

This report should be cited as follows:

Federal Interagency Committee for Wetland Delineation. 1989. Federal Manual for Identifying and Delin-eating Jurisdictional Wetlands. U.S. Army Corps of Engineers, U.S. Environmental Protection Agency,U.S. Fish and Wildlife Service, and U.S.D.A. Soil Conservation Service, Washington, D.C. Cooperativetechnical publication. 76 pp. plus appendices.

Table of ContentsPage

Preface i

Part I. Introduction 1

Purpose 1Organization of the Manual 1Use of the Manual 1Background 1Federal Wetland Definitions 2

Section 404 of the Clean Water Act 2Food Security Act of 1985 2Fish and Wildlife Service's Wetland Classification System 3Summary of Federal Definitions 3

Part n. Mandatory Technical Criteria for Wetland Identification 5

Hydrophytic Vegetation 5Hydrophytic Vegetation Criterion 5

Hydric Soils 6Hydric Soil Criterion 6

Wetland Hydrology 7Wetland Hydrology Criterion 7

Summary 7

Part in. Field Indicators and Other Available Information 9

Hydrophytic Vegetation 9Dominant Vegetation 9Field Indicators 10Other Sources of Information 10

Hydric Soils 10Soil Colors 11Hydric Organic Soils 12Hydric Mineral Soils 12National and State Hydric Soils Lists 12Soil Surveys 13Use of the Hydric Soils List and Soil Surveys 13Field Indicators 13

Wetland Hydrology 15Recorded Data 16Aerial Photographs 16Field Indicators 16

Page

Part IV. Methods for Identification and Delineation of Wetlands 21

Selection of a Method 21Description of Methods 23

Offsite Determinations 23Offsite Determination Method 23

Onsite Determinations 24Routine Onsite Determination Method 31

Hydric Soil Assessment Procedure 31Plant Community Assessment Procedure 33

Intermediate-level Onsite Determination Method 35Comprehensive Onsite Determination Method 39

Quadrat Sampling Procedure 40Point Intercept Sampling Procedure 46

Disturbed Area and Problem Area Wetland Determination Procedures 50Disturbed Areas 50Problem Area Wetlands 55

References 61

Glossary 65

Appendix A. Selected Wetland References A-lAppendix B. Examples of Data Sheets B-lAppendix C. Sample Calculation for Herb Stratum Dominants C-1Appendix D. Sample Problem for Application of Point Intercept Sampling Method D-1

iv

PartIntroduction

offered to provide users with a selection of meth-ods that range from office determinations to de-tailed field determinations. If the user departs fromthese methods, the reasons for doing so should bedocumented.

Purpose

1.0. The purpose of this manual is toprovide users with mandatory technicalcriteria, field indicators and other sourc-es of information, and recommendedmethods to determine whether an area is

jurisdictional wetland or not, and to delineate theupper boundary of these wetlands. The documentcan be used to identify jurisdictional wetlands sub-ject to Section 404 of the Clean Water Act and tothe "Swampbuster" provision of the Food SecurityAct, or to identify vegetated wetlands in general forthe National Wetlands Inventory and other purpos-es. The term "wetland" as used throughout thismanual refers to jurisdictional wetlands for use byFederal agencies. This manual, therefore, providesa single, consistent approach for identifying anddelineating wetlands from a multi-agency Federalperspective.

Organization of the Manual

1.1. The manual is divided into four major parts:Part I — Introduction, Part II — Mandatory Tech-nical Criteria for Wetland Identification, Part in —Field Indicators and Other Available Information,and Part IV — Methods for Identification and De-lineation of Wetlands. References, a glossary oftechnical terms, and appendices are included at theback of the manual.

Use of the Manual

1.2. The manual should be used for identificationand delineation of wetlands in the United States.Emphasis for delineation is on the upper boundaryof wetlands (i.e., wetland-upland boundary) andnot on the lower boundary between wetlands andother aquatic habitats. The technical criteria forwetland identification presented in Part n are man-datory, while the methods presented in Part IV arerecommended approaches. Alternative methods are

Background

1.3. At the Federal level, four agencies are princi-pally involved with wetland identification and de-lineation: Army Corps of Engineers (CE), Environ-mental Protection Agency (EPA), Fish and WildlifeService (FWS), and Soil Conservation Service(SCS). Each of these agencies have developedtechniques for identifying the limits of wetlands forvarious purposes.

1.4. The CE and EPA are responsible for makingjurisdictional determinations of wetlands regulatedunder Section 404 of the Clean Water Act (former-ly known as the Federal Water Pollution ControlAct, 33 U.S.C. 1344). The CE also makes juris-dictional determinations under Section 10 of theRivers and Harbors Act of 1899 (33 U.S.C 403).Under Section 404, the Secretary of the Army, act-ing through the Chief of Engineers, is authorized toissue permits for the discharge of dredged or fillmaterials into the waters of the United States, in-cluding wetlands, with program oversight by EPA.The EPA has the authority to make final determina-tions on the extent of Clean Water Act jurisdiction.The CE also issues permits for filling, dredging,and other construction in certain wetlands underSection 10. Under authority of the Fish and Wild-life Coordination Act, the FWS and the NationalMarine Fisheries Service review applications forthese Federal permits and provide comments to theCE on the environmental impacts of proposedwork. In addition, the FWS is conducting an in-ventory of the Nation's wetlands and is producinga series of National Wetlands Inventory maps forthe entire country. While the SCS has been in-volved in wetland identification since 1956, it hasrecently become more deeply involved in wetlanddeterminations through the "Swampbuster" provi-sion of the Food Security Act of 1985.

1.5. The CE and EPA have developed technicalmanuals for identifying and delineating wetlandssubject to Section 404 (Environmental Laboratory1987 and Sipple 1988, respectively). The SCS hasdeveloped procedures for identifying wetlands for

compliance with "Swampbuster." While it has noformal method for delineating wetland boundaries,the FWS has established guidelines for identifyingwetlands in the form of its official wetland classifi-cation system report (Cowardin, et al. 1979).

1.6. In early 1988, the CE and EPA resumed pre-vious discussions on the possibilities of mergingtheir manuals into a single document, since bothmanuals were produced in support of Section 404of the Clean Water Act. At that time, it was recom-mended that the FWS and SCS be invited to partic-ipate in the talks to take advantage of their technicalexpertise in wetlands and to discuss the possibili-ties of a joint interagency wetland identificationmanual. On May 19-20, 1988, the first meetingwas held in Washington, D.C., to discuss technicaldifferences between the CE and EPA manuals. Af-ter the meeting, it was decided that a second meet-ing should be held to resolve technical issues andto attempt to merge the two manuals and possiblydevelop an interagency manual for the four agen-cies. This meeting was held on August 29-31,1988, at Harpers Ferry, West Virginia. Each of thefour Federal agencies (CE, EPA, FWS, and SCS)was represented by three persons, with outside fa-cilitators moderating the session. During the three-day meeting, the four agencies reached agreementon the technical criteria for identifying and delineat-ing wetlands and agreed to merge the existing pub-lished methods (CE, EPA, and SCS) into a singlewetland delineation manual. A draft combinedmanual was prepared, and then reviewed by the in-teragency group. On January 10,1989, the manualwas formally adopted by the four agencies as therecommended manual for identifying and delineat-ing wetlands in the United States.

Federal Wetland Definitions

1.7. Several definitions have been formulated atthe Federal level to define "wetland" for variouslaws, regulations, and programs. These major Fed-eral definitions are cited below in reference to theirguiding document along with a few comments ontheir key elements.

Section 404 of the Clean Water Act

1.8. The following definition of wetland is the reg-ulatory definition used by the EPA and CE for ad-ministering the Section 404 permit program:

Those areas that are inundated or saturatedby surface or groundwater at a frequencyand duration sufficient to support, and thatunder normal circumstances do support, aprevalence of vegetation typically adaptedfor life in saturated soil conditions. Wetlandsgenerally include swamps, marshes, bogs,and similar areas.

(EPA, 40 CFR 230.3 and CE, 33 CFR 328.3)

1.9. This definition emphasizes hydrology, vegeta-tion, and saturated soils. The Section 404 regula-tions also deal with other "waters of the UnitedStates" such as open water areas, mud flats, coralreefs, riffle and pool complexes, vegetated shal-lows, and other aquatic habitats.

Food Security Act of 1985

1.10. The following wetland definition is used bythe SCS for identifying wetlands on agriculturalland in assessing farmer eligibility for U.S. Depart-ment of Agriculture program benefits under the"Swampbuster" provision of this Act:

Wetlands are defined as areas that have apredominance of hydric soils and that are in-undated or saturated by surface or groundwater at a frequency and duration sufficientto support, and under normal circumstancesdo support, a prevalence of hydrophyticvegetation typically adapted for life in satu-rated soil conditions, except lands in Alaskaidentified as having a high potential for agri-cultural development and a predominance ofpermafrost soils.*

(National Food Security Act Manual, 1988)

^Special Note: The Emergency Wetlands ResourcesAct of 1986 also contains this definition, but with-out the exception for Alaska.

1.11. This definition specifies hydrology, hydro-phytic vegetation, and hydric soils. Any area thatmeets the hydric soil criteria (defined by the Na-tional Technical Committee for Hydric Soils) isconsidered to have a predominance of hydric soils.The definition also makes a geographic exclusionfor Alaska, so that wetlands in Alaska with a highpotential for agricultural development and a pre-dominance of permafrost soils are exempt from therequirements of the Act.

Fish and Wildlife Service's Wetland Clas-sification System

1.12. The FWS in cooperation with other Federalagencies, State agencies, and private organizationsand individuals developed a wetland definition forconducting an inventory of the Nation's wetlands.This definition was published in the FWS's publi-cation "Classification of Wetlands and DeepwaterHabitats of the United States" (Cowardin, et al.1979):

Wetlands are lands transitional between ter-restrial and aquatic systems where the watertable is usually at or near the surface or theland is covered by shallow water. For pur-poses of this classification wetlands musthave one or more of the following three at-tributes: (1) at least periodically, the landsupports predominantly hydrophytes, (2)the substrate is predominantly undrained

hydric soil, and (3) the substrate is nonsoiland is saturated with water or covered byshallow water at some time during thegrowing season of each year.

1.13. This definition includes both vegetated andnonvegetated wetlands, recognizing that sometypes of wetlands lack vegetation (e.g., mud flats,sand flats, rocky shores, gravel beaches, and sandbars). The classification system also defines "deep-water habitats" as "permanently flooded lands lyingbelow the deepwater boundary of wetlands." Deep-water habitats include estuarine and marine aquaticbeds (similar to "vegetated shallows" of Section404). Open waters below extreme low water atspring tides in salt and brackish tidal areas and usu-ally below 6.6 feet in inland areas and freshwatertidal areas are also included in deepwater habitats.

Summary of Federal Definitions

1.14. The CE, EPA, and SCS wetland definitionsinclude only areas that are vegetated under normalcircumstances, while the FWS definition encom-passes both vegetated and nonvegetated areas. Ex-cept for the FWS inclusion of nonvegetated areasas wetlands and the exemption for Alaska in theSCS definition, all four wetland definitions areconceptually the same; they all include three basicelements - hydrology, vegetation, and soils - foridentifying wetlands.

PartMandatory TechnicalCriteria for Wetland

Identification

2.0. Wetlands possess three essentialcharacteristics: (1) hydrophytic vegeta-tion, (2) hydric soils, and (3) wetlandhydrology, which is the driving force

creating all wetlands. These characteristics and theirtechnical criteria for identification purposes are de-scribed in the following sections. The three techni-cal criteria specified are mandatory and must all bemet for an area to be identified as wetland. There-fore, areas that meet these criteria are wetlands.

Hydrophytic Vegetation

2.1. For purposes of this manual, hydrophyticvegetation is defined as macrophytic plant lifegrowing in water, soil or on a substrate that is atleast periodically deficient in oxygen as a result ofexcessive water content. Nearly 7,000 vascularplant species have been found growing in U.S.wetlands (Reed 1988). Out of these, only about 27percent are "obligate wetland" species that nearlyalways occur in wetlands under natural conditions.This means that the majority of plant «pecies grow-ing in wetlands also grow in nonwetlands in vary-ing degrees.

2.2. The FWS in cooperation with CE, EPA, andSCS has published the "National List of Plant Spe-cies That Occur in Wetlands" from a review of thescientific literature and review by wetland expertsand botanists (Reed 1988). The list separates vas-cular plants into four basic groups, commonlycalled "wetland indicator status," based on a plantspecies' frequency of occurrence in wetlands: (1)obligate wetland plants (OBL) that occur almost al-ways (estimated probability >99%) in wetlands un-der natural conditions; (2) facultative wetland plants(FACW) that usually occur in wetlands (estimatedprobability 67-99%), but occasionally are found innonwetlands; (3) facultative plants (FAQ that arcequally likely to occur in wetlands or nonwetlands(estimated probability 34-66%); and (4) facultative

upland plants (FACU) that usually occur in non-wetlands (estimated probability 67-99%), but occa-sionally are found in wetlands (estimated probabili-ty 1-33%). If a species occurs almost always(estimated probability >99%) in nonwetlands undernatural conditions, it is considered an obligate up-land plant (UPL). These latter plants do not usuallyappear on the wetland plant list; they are listed onlywhen found in wetlands with a higher probabilityin one region of the country. If a species is not onthe list, it is presumed to be an obligate uplandplant. The "National List of Plant Species That Oc-cur in Wetlands" has been subdivided into regionaland state lists. There is a formal procedure to peti-tion the interagency plant review committee formaking additions, deletions, and changes in indica-tor status. Since the lists are periodically updated,the U.S. Fish and Wildlife Service should be con-tacted to be sure that the most current version is be-ing used for wetland determinations. The appropri-ate plant list for a specific geographic region shouldbe used when making a wetland determination andevaluating whether the following hydrophytic veg-etation criterion is satisfied.

Hydrophytic Vegetation Criterion

2.3. An area has hydrophytic vegetationwhen, under normal circumstances: (1)more than 50 percent of the compositionof the dominant species from all strata areobligate wetland (OBL), facultative wet-land (FACW), and/or facultative (FAC)species, or (2) a frequency analysis of allspecies within the community yields aprevalence index value of less than 3.0(where OBL = 1.0, FACW = 2.0, FAC =3.0, FACU = 4.0, and UPL = 5.0). CAU-TION: When a plant community has lessthan or equal to 50 percent of the domi-nant species from all strata represented byOBL, FACW, and/or FAC species, or afrequency analysis of all species withinthe community yields a prevalence indexvalue of greater than or equal to 3.0, andhydric soils and wetland hydrology arepresent, the area also has hydrophyticvegetation. (Note: These areas are consid-ered problem area wetlands.)

2.4. For each stratum (e.g., tree, shrub,and herb) in the plant community, domi-nant species are the most abundant plantspecies (when ranked in descending order

of abundance and cumulatively totaled)that immediately exceed 50 percent of thetotal dominance measure (e.g., basal areaor areal coverage) for the stratum, plusany additional species comprising 20 per-cent or more of the total dominance meas-ure for the stratum. All dominants aretreated equally in determining the presenceof hydrophytic vegetation.

2.5. (Note: The "National List of Plant Speciesthat Occur in Wetlands" uses a plus (+) sign or aminus (-) sign to specify a higher or lower portionof a particular wetland indicator frequency for thethree facultative-type indicators; for purposes ofidentifying hydrophytic vegetation according to thismanual, however, FACW+, FACW-, FAC+, andFAC are included as FACW and FAC, respective-ly, in the hydrophytic vegetation criterion.)

Hydric Soils

2.6. Hydric soils are defined as soils that are satu-rated, flooded, or ponded long enough during thegrowing season to develop anaerobic conditions inthe upper part (U.S.D.A. Soil Conservation Serv-ice 1987). In general, hydric soils are flooded,ponded, or saturated for usually one week or moreduring the period when soil temperatures are abovebiologic zero 41° F as defined by "Soil Taxonomy"(U.S.D.A. Soil Survey Staff 1975). These soilsusually support hydrophytic vegetation. The Na-tional Technical Committee for Hydric Soils hasdeveloped criteria for hydric soils and a list of theNation's hydric soils (U.S.D.A. Soil ConservationService 1987). (Note: Caution must be exercised inusing the hydric soils list for determining the pres-ence of hydric soil at specific sites; see p. 12.)

Hydric Soil Criterion

2.7. An area has hydric soils when theNational Technical Committee for HydricSoils (NTCHS) criteria for hydric soilsare met.

NTCHS Criteria for Hydric Soils(U.S.D.A. Soil Conservation Service1987):

2. Soils in Aquic suborders, Aquic sub-groups, Albolls suborder, Salorthidsgreat group, or Pell great groups ofVertisols that are:

a. somewhat poorly drained and havewater table less than 0.5 feet fromthe surface for a significant period(usually a week or more) duringthe growing season, or

b. poorly drained or very poorlydrained and have either:

(1) water table at less than 1.0feet from the surface for a sig-nificant period (usually a weekor more) during the growingseason if permeability is equalto or greater than 6.0 inches/hour in all layers within 20inches, or

(2) water table at less than 1.5feet from the surface for a sig-nificant period (usually a weekor more) during the growingseason if permeability is lessthan 6.0 inches/hour in anylayer within 20 inches; or

3. Soils that are ponded for long dura-tion or very long duration during thegrowing season; or

4. Soils that are frequently flooded forlong duration cr very long durationduring the growing season."

(Note: Long duration is defined as inundation for asingle event that ranges from seven days to onemonth; very long duration is defined as inundationfor a single event that is greater than one month; fre-quently flooded is defined as flooding likely to occuroften under usual weather conditions - more than 50percent chance of flooding in any year or more than50 times in 100 years. Other technical terms in theNTCHS criteria for hydric soils are generally de-fined in the glossary.)

"1. All Histosols except Folists; or

Wetland Hydrology

2.8. Permanent or periodic inundation, or soil sat-uration to the surface, at least seasonally, are thedriving forces behind wetland formation. The pres-ence of water for a week or more during the grow-ing season typically creates anaerobic conditions inthe soil, which affect the types of plants that cangrow and the types of soils that develop. Numer-ous factors influence the wetness of an area, in-cluding precipitation, stratigraphy, topography,soil permeability, and plant cover. All wetlandsusually have at least a seasonal abundance of wa-ter. This water may come from direct precipitation,overbank flooding, surface water runoff due toprecipitation or snow melt, ground water dis-charge, or tidal flooding. The frequency and dura-tion of inundation and soil saturation vary widelyfrom permanent flooding or saturation to irregularflooding or saturation. Of the three technical criteriafor wetland identification, wetland hydrology is of-ten the least exact and most difficult to establish inthe field, due largely to annual, seasonal, and dailyfluctuations.

Wetland Hydrology Criterion

2.9. An area has wetland hydrology whensaturated to the surface or inundated atsome point in time during an average rain-fall year, as defined below:

1. Saturation to the surface normallyoccurs when soils in the followingnatural drainage classes meet thefollowing conditions:

A. In somewhat poorly drainedmineral soils, the water table isless than 0.5 feet from the sur-face for usually one week ormore during the growing season;or

B. In low permeability (

8

PartiField Indicators andOther AvailableInformation

3.0. When conducting a field inspec-tion to make a wetland determination,the three identification criteria, listed inPart II of this manual, alone may notprovide enough information for users todocument whether or not the criteria

themselves (i.e., hydrophytic vegetation, hydricsoils, and wetland hydrology) are met. Variousphysical properties or other signs can be readilyobserved in the field to determine whether the threewetland identification criteria are satisfied. Besidesthese field indicators, good baseline informationmay be available from site-specific studies, pub-lished reports, or other written material on wet-lands. In the following sections, field indicatorsand primary sources of information for each of thethree criteria are presented to help the user identifywetlands.

Hydrophytic Vegetation

3.1. All plants growing in wetlands have adaptedin one way or another to life in permanently or per-iodically inundated or saturated soils. Some plantshave developed structural or morphological adapta-tions to inundation or saturation. These features,while indicative of hydrophytic vegetation, areused as indicators of wetland hydrology in thismanual, since they are a response to inundation andsoil saturation. Probably all plants growing in wet-lands possess physiological mechanisms to copewith prolonged periods of anaerobic soil condi-tions. Because they are not observable in the field,physiological and reproductive adaptations are notincluded in this manual.

3.2. Persons making wetland determinationsshould be able to identify at least the dominant wet-land plants in each stratum (layer of vegetation) ofa plant community. Plant identification requires use

of field guides or more technical taxonomic manu-als (see Appendix A for sample list). When neces-sary, seek help in identifying difficult species.Once a plant is identified to genus and species, oneshould then consult the appropriate Federal list ofplants that occur in wetlands to determine the "wet-land indicator status" of the plant (see p. 5). Thisinformation will be used to help determine if hy-drophytic vegetation is present.

Dominant Vegetation

3.3. Dominance as used in this manual refersstrictly to the spatial extent of a species that is di-rectly discernable or measurable in the field. Whenidentifying dominant vegetation within a givenplant community, one should consider dominancewithin each stratum. All dominants are treatedequally in characterizing the plant community to de-termine whether hydrophytic vegetation is present.The most abundant plant species (when ranked indescending order of abundance and cumulativelytotaled) that immediately exceed 50 percent of thetotal dominance measure for a given stratum, plusany additional species comprising 20 percent ormore of the total dominance measure for that stra-tum are considered dominant species for the stra-tum. Dominance measures include percent arealcoverage and basal area, for example.

3.4. Vegetative strata for which dominants shouldbe determined may include: (1) tree Q>5.0 inchesdiameter at breast height (dbh) and 20 feet or tall-er); (2) sapling (0.4 to

given plant community. These are accepted meth-ods for evaluating plant communities.

Field Indicators

3.6. Having established the community dominantsfor each stratum or performed a frequency analysis,hydrophytic vegetation is considered present if:

1) OBL species comprise all dominants in theplant community (Note: In these cases, the area canbe considered wetland without detailed examinationof soils and hydrology, provided significant hydro-logic modifications are not evident); or

2) OBL species do not dominate each stratum,but more than 50 percent of the dominants of allstrata are OBL, FACW, or FAC species (includingFACW+, FACW-, FAC+, and FAC-); or

3) A plant community has a visually estimatedpercent coverage of OBL and FACW species thatexceed the coverage of FACU and UPL species; or

4) A frequency analysis of all species within thecommunity yields a prevalence index value of lessthan 3.0 (where OBL = 1.0, FACW = 2.0, FAC =3.0, FACU = 4.0, and UPL = 5.0); or

5) A plant community has less than or equal to50 percent of the dominant species from all stratarepresented by OBL, FACW, and/or FAC species,or a frequency analysis for all species within thecommunity yields a prevalence index value greaterthan or equal to 3.0, and hydric soils and wetlandhydrology are present. (Note: In other words, if thehydric soil and wetland hydrology criteria are met,then the vegetation is considered hydrophytic. Forpurposes of this manual, these situations are treatedas disturbed or problem area wetlands becausethese plant communities are usually nonwetlands.)

Other Sources of Information

3.7. Besides learning the field indicators of hydro-phytic vegetation presented above, one should alsobecome familiar with the technical literature on wet-lands, especially for one's geographic region.Sources of available literature include: taxonomicplant manuals and field guides; scientific journalsdealing with botany, ecology, and wetlands in par-

ticular; technical government reports on wetlands;proceedings of wetland workshops, conferences,and symposia; and the FWS's national wetlandplant database, which contains habitat informationon about 7,000 plant species. Appendix A presentsexamples of the first four sources of information.In addition, the FWS's National Wetlands Invento-ry (NWI) maps provide information on locations ofhydrophytic plant communities that may be studiedin the field to improve one's knowledge of suchcommunities in particular regions.

Hydric Soils

3.8. Due to their wetness during the growing sea-son, hydric soils usually develop certain morpho-logical properties that can be readily observed inthe field. Prolonged anaerobic soil conditions typi-cally lower the soil redox potential and causes achemical reduction of some soil components, main-ly iron oxides and manganese oxides. This reduc-tion affects solubility, movement, and aggregationof these oxides which is reflected in the soil colorand other physical characteristics that are usuallyindicative of hydric soils. (Note: Much of the back-ground material for this section was taken from"Hydric Soils of New England" [Tiner and Vene-man 1987].)

3.9. Soils are separated into two major types onthe basis of material composition: organic soil andmineral soil. In general, soils with at least 18 inch-es of organic material in the upper part of the soilprofile and soils with organic material resting onbedrock are considered organic soils (Histosols).Soils largely composed of sand, silt, and/or clayare mineral soils. (For technical definitions, see"Soil Taxonomy", U.S.D.A. Soil Survey Staff1975).

3.10. Accumulation of organic matter in most or-ganic soils results from prolonged anaerobic soilconditions associated with long periods of submer-gence or soil saturation during the growing season.These saturated conditions impede aerobic decom-position (oxidation) of the bulk organic materialssuch as leaves, stems, and roots, and encouragetheir accumulation over time as peat or muck. Con-sequently, most organic soils are characterized asvery poorly drained soils. Organic soils typicallyform in waterlogged depressions, and peat or muckdeposits may range from about two feet to more

10

than 30 feet deep. Organic soils also develop inlow-lying areas along coastal waters where tidalflooding is frequent.

3.11. Hydric organic soils are subdivided intothree groups based on the presence of identifiableplant material: (1) muck (Saprists) in which two-thirds or more of the material is decomposed andless than one-third of the plant fibers are identifia-ble; (2) peat (Fibrists) in which less than one-thirdof 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 whichthe ratio of decomposed to identifiable plant matteris more nearly even (U.S.D.A. Soil Survey Staff1975). A fourth group of organic soils (Folists) ex-ists in tropical and boreal mountainous areas whereprecipitation exceeds the evapotranspiration rate,but these soils are never saturated for more than afew days after heavy rains and thus do not developunder hydric conditions. All organic soils, with theexception of the Folists, are hydric soils.

3.12. When less organic material accumulates insoil, the soil is classified as mineral soil. Somemineral soils may have thick organic surface layersdue to heavy seasonal rainfall or a high water table,yet they are still composed largely of mineral matter(Ponnamperuma 1972). Mineral soils that are cov-ered with moving (flooded) or standing (ponded)water for significant periods or are saturated for ex-tended periods during the growing season are clas-sified as hydric mineral soils. Soil saturation mayresult from low-lying topographic position,groundwater seepage, or the presence of a slowlypermeable layer (e.g., clay, confining bedrock, orhardpan).

3.13. The duration and depth of soil saturation areessential criteria for identifying hydric soils andwetlands. Soil morphological features are com-monly used to indicate long-term soil moisture re-gimes (Bouma 1983). The two most widely recog-nized features that reflect wetness in mineral soilsare gleying and mottling.

3.14. Simply described, gleyed soils are predomi-nantly neutral gray in color and occasionally green-ish or bluish gray. In gleyed soils, the distinctivecolors result from a process known as gleization.Prolonged saturation of mineral soil converts ironfrom its oxidized (ferric) form to its reduced (ferro-us) state. These reduced compounds may be com-pletely removed from the soil, resulting in gleying

(Veneman, et al. 1976). Mineral soils that are al-ways saturated arc uniformly gleyed throughout thesaturated area. Soils gleyed to the surface layer arehydric soils. These soils often show evidence ofoxidizing conditions only along root channels.Some nonhydric soils have gray layers (E-horizons) immediately below the surface layer thatare gray for reasons other than saturation (e.g.,leaching due to organic acids). These soils oftenhave brighter (e.g., brownish or reddish) layersbelow the gray layer and can be recognized as non-hydric on that basis.

3.15. Mineral soils that are alternately saturatedand oxidized (aerated) during the year are usuallymottled in the part of the soil that is seasonally wet.Mottles are spots or blotches of different colors orshades of colors interspersed with the dominant(matrix) color. The abundance, size, and color ofthe mottles usually reflect the duration of the satu-ration period and indicate whether or not the soil ishydric. Mineral soils that are predominantly gray-ish with brown or yellow mottles are usually satu-rated for long periods during the growing seasonand are classified as hydric. Soils that are predomi-nantly brown or yellow with gray mottles are satu-rated for shorter periods and may not be hydric.Mineral soils that are never saturated are usuallybright-colored and are not mottled. Realize, how-ever, that in some hydric soils, mottles may not bevisible due to masking by organic matter (Parker,« a/. 1984).

3.16. It is important to note that the gleization andmottle formation processes are strongly influencedby the activity of certain soil microorganisms.These microorganisms reduce iron when the soilenvironment is anaerobic, that is, when virtually nofree oxygen is present, and when the soil containsorganic matter. If the soil conditions are such thatfree oxygen is present, organic matter is absent, ortemperatures are too low (below 41 °F) to sustainmicrobial activity, gleization will not proceed andmottles will not form, even though the soil may besaturated for prolonged periods of time (Diers andAnderson 1984).

Soil Colors

3.17. Soil colors often reveal much about a soil'swetness, that is, whether the soil is hydric or non-hydric. Scientists and others examining the soil candetermine the approximate soil color by comparing

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the soil sample with a Munsell soil color chart. Thestandardized Munsell soil colors are identified bythree components: hue, value, and chroma. Thehue is related to one of the main spectral colors:red, yellow, green, blue, or purple, or various mix-tures of these principal colors. The value refers tothe degree of lightness, while the chroma notationindicates the color strength or purity. In the Mun-sell soil color book, each individual hue has itsown page, each of which is further subdivided intounits for value (on the vertical axis) and chroma(horizontal axis). Although theoretically each soilcolor represents a unique combination of hues, val-ues, and chromas, the number of combinationscommon in the soil environment usually is limited.Because of this situation and the fact that accuratereproduction of each soil color is expensive, theMunsell soil color book contains a limited numberof combinations of hues, values, and chromas. Thecolor of the soil matrix or a mottle is determined bycomparing a soil sample with the individual colorchips in the soil color book. The appropriate Mun-sell color name can be read from the facing page inthe "Munsell Soil Color Charts" (Kollmorgen Cor-poration 1975). Chromas of 2 or less are consid-ered low chromas and are often diagnostic of hy-dric soils. Low chroma colors include black,various shades of gray, and the darker shades ofbrown and red.

Hydric Organic Soils

3.18. Hydric organic soils can be easily recog-nized as black-colored muck and/or as black to darkbrown-colored peat. Distinguishing mucks frompeats based on the relative degree of decompositionis fairly simple. In mucks (Saprists), almost all ofthe plant remains have been decomposed beyondrecognition. When rubbed, mucks feel greasy andleave hands dirty. In contrast, the plant remains inpeats (Fibrists) show very little decomposition andthe original constituent plants can be recognizedfairly easily. When the organic material is rubbedbetween the fingers, most plant fibers will remainidentifiable, leaving hands relatively clean. Be-tween the extremes of mucks and peats, organicsoils with partially decomposed plant fibers (Hem-ists) can be recognized. In peaty mucks up to two-thirds of the plant fibers can be destroyed by rub-bing the materials between the fingers, while inmucky peats up to two-thirds of the plant remainsare still recognizable after rubbing.

3.19. Besides the dominance of organic matter,many organic soils (especially in tidal marshes) alsoemit an odor of rotten eggs when hydrogen sulfideis present. Sulfides are produced only in a stronglyreducing environment.

Hydric Mineral Soils

3.20. Hydric mineral soils are often more difficultto identify than hydric organic soils because mostorganic soils are hydric, while most mineral soilsare not. A thick dark surface layer, grayish subsur-face and subsoil colors, the presence of orange orreddish brown (iron) and/or dark reddish brown orblack (manganese) mottles or concretions near thesurface, and the wet condition of the soil may helpidentify the hydric character of many mineral soils.The grayish subsurface and subsoil colors andthick, dark surface layers are the best indicators ofcurrent wetness, since the orange-colored mottlesare very insoluble and once formed may remain in-definitely as relict mottles of former wetness (Diersand Anderson 1984).

National and State Hydric Soils Lists

3.21. The SCS in cooperation with the NationalTechnical Committee for Hydric Soils (NTCHS)has prepared a list of the Nation's hydric soils.State lists have also been prepared for statewideuse. The national and State lists identify those soilseries that meet the hydric soil criteria according toavailable soil interpretation records in SCS's soilsdatabase. These lists are periodically updated, somake sure the list being used is the current list Thelists facilitate use of SCS county soil surveys foridentifying potential wetlands. One must be careful,however, in using the soil survey, because a soilmap unit of an upland (nonwetland) soil may haveinclusions of hydric soil that were not delineated onthe 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 hydricsoils lists because they were not given a seriesname at the time of mapping.

3.22. Because of these limitations of the nationaland State lists, the SCS also maintains lists of hy-dric soil map units for each county in the UnitedStates. These lists may be obtained from local SCSdistrict offices and are the preferred lists to be usedwhen locating areas of hydric soils. The hydric soil

12

map units lists identify all map units that arc eithernamed by a hydric soil or that have a potential ofhaving hydric soil inclusions. The lists provide themap unit symbol, the name of the hydric soil partor parts of the map unit, information on the hydricsoil composition of the map unit, and probablelandscape position of hydric soils in the map unitdelineation. The county lists also include map unitsnamed by miscellaneous land types or higher levelsin "Soil Taxonomy" that meet hydric soil criteria.

Soil Surveys

3.23. The SCS publishes county soil surveys forareas where soil mapping is completed. Soil sur-veys that meet standards of the National Coopera-tive Soil Survey (NCSS) are used to identify delin-eations of hydnc soils. These soil surveys may bepublished (completed) or unpublished (on file at lo-cal SCS district offices). Published soil surveys ofan area may be obtained from the local SCS districtoffice or the Agricultural Extension Service office.Unpublished maps may be obtained from the localSCS district office.

3.24. The NCSS maps four kind of map units: (1)consociations, (2) complexes, (3) associations, and(4) undifferentiated groups. Consociations are soilmap units named for a single kind of soil (taxon) ormiscellaneous area. Seventy-five percent of thearea is similar to the taxon for which the unit isnamed. When named by a hydric soil, the map unitis considered a hydric soil map unit for wetland de-terminations. However, small areas within thesemap units may not be hydric and should be exclud-ed in delineating wetlands.

3.25. Complexes and associations are soil mapunits named by two or more kinds of soils (taxa) ormiscellaneous areas. If all taxa for which these mapunits are named are hydric, the soil map unit maybe considered a hydric soil map unit for wetlanddeterminations. If only part of the map unit is madeup of hydric soils, only those portions of the mapunit that are hydric arc considered in wetland deter-minations.

3.26. Undifferentiated groups arc soil map unitsnamed by two or more kinds of soils or miscellane-ous areas. These units are distinguished from theothers in that "and" is used as a conjunction in thename, while dashes are used for complexes and as-sociations. If all components are hydric, the map

unit may be considered a hydric soil map unit. Ifone or more of the soils for which the unit isnamed are nonhydric, each area must be examinedfor the presence of hydric soils.

Use of the Hydric Soils List andSoil Surveys

3.27. The hydric soils list and county soil surveysmay be used to help determine if the hydric soil cri-terion is met in a given area. When making a wet-land determination, one should first locate the areaof concern on a soil survey map and identify thesoil map units for the area. The list of hydric soilsshould be consulted to determine whether the soilmap units are hydric. If hydric soil map units arenoted, then one should examine the soil in the fieldand compare its morphology with the correspond-ing hydric soil description in the soil survey report.If the soil's characteristics match those describedfor hydric soil, then the hydric soil criterion is met,unless the soil has been effectively drained (seedisturbed areas section, p. 50). In the absence ofsite-specific information, hydric soils also may berecognized by field indicators.

Field Indicators

3.28. Several field indicators are available for de-termining whether a given soil meets the definitionand criteria for hydric soils. Other factors to con-sider in recognizing hydric soils include obligatewetland plants, topography, observed or recordedinundation or soil saturation, and evidence of hu-man alterations, e.g., drainage and filling. Any oneof the following may indicate that hydric soils arepresent:

1) Organic Soils - Various peats and mucks areeasily recognized as hydric soils. Organic soils thatare cropped are often drained, yet the water table isclosely managed to minimize oxidation of organicmatter. These soils often retain their hydric soilcharacteristics and, if so, meet the wetland hydrol-ogy criterion.

2) Histic epipedons - A histic epipedon (organ-ic surface layer) is an 8- to 16-inch organic layer ator near the surface of a hydric mineral soil that issaturated with water for 30 consecutive days ormore in most years. It contains a minimum of 20percent organic matter when no clay is present or a

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minimum of 30 percent organic matter when claycontent is 60 percent or greater. Soils with histicepipedons are inundated or saturated for sufficientperiods to greatly retard aerobic decomposition oforganic matter, and are considered hydric soils. Ingeneral, a histic epipedon is a thin surface layer ofpeat or muck if the soil has not been plowed(U.S.D.A. Soil Survey Staff 1975). Histic epiped-ons are technically classified as Oa, Oe, or Oi sur-face layers, and in some cases the terms "mucky"or "peaty" are used as modifiers to the mineral soiltexture term, e.g., mucky loam.

3) Sulfidic material - When soils emit an odorof rotten eggs, hydrogen sulfide is present. Suchodors are only detected in waterlogged soils that areessentially permanently saturated and have sulfidicmaterial within a few inches of the soil surface.Sulfides are produced only in reducing environ-ment. Under saturated conditions, the sulfates inwater are biologically reduced to sulfides as the or-ganic materials accumulate.

4) Aquic or peraquic moisture regime - An aq-uic moisture regime is a reducing one, i.e., it is vir-tually free of dissolved cxygen, because the soil issaturated by ground water or by water of the capil-lary fringe (U.S.D.A. Soil Survey Staff 1975). Thesoil is considered saturated if water stands in an un-lined borehole at a shallow enough depth that thecapillary fringe reaches the soil surface, except innoncapillary pores. Because dissolved oxygen isremoved from ground water by respiration of mi-croorganisms, roots, and soil fauna, it is also im-plicit that the soil temperature be above biologiczero (41°F) at some time while the soil is saturated.Soils with peraquic moisture regimes are character-ized by the presence of ground water always at ornear the soil surface. Examples include soils of tidalmarshes and soils of closed, landlocked depres-sions that are fed by permanent streams. Soils withperaquic moisture regimes are always hydric undernatural conditions. Soils with aquic moisture re-gimes are usually hydric, but the NTCHS hydricsoil criteria should be verified in the field.

5) Direct observations of reducing soil condi-tions - Soils saturated for long or very long dura-tion will usually exhibit reducing conditions at thetime of saturation. Under such conditions, ions ofiron are transformed from a ferric (oxidized) state toa ferrous (reduced) state. This reduced conditioncan often be detected in the field by use of a colon-metric field test kit. When a soil extract changes to a

pink color upon addition of a-a-dipyridil, ferrousiron is present, which indicates a reducing soil en-vironment at the time of the test. A negative result(no pink color) only indicates that the soil is not re-duced at this moment; it does not imply that the soilis not reduced during the growing season. Further-more, the test is subject to error due to the rapidchange of ferrous iron to ferric iron when the soilis exposed to air and should only be used by exper-ienced technicians. (CAUTION: This test cannot beused in hydric mineral soils having low iron con-tent or in organic soils. Also it does not determinethe duration of reduced conditions.)

6) Gleyed, low chroma, and low chromafmottled soils - The colors of various soil compo-nents are often the most diagnostic indicator of hy-dric soils. Colors of these components are stronglyinfluenced by the frequency and duration of soilsaturation which leads to reducing soil conditions.Hydric mineral soils will be either gleyed or willhave low chroma matrix with or without brightmottles.

A) Gleyed soils - Gleying (bluish, green-ish, or grayish colors) immediately below the A-horizon is an indication of a markedly reduced soil,and gleyed soils are hydric soils. Gleying can oc-cur in both mottled and unmottled soils. Gleyedsoil conditions can be determined by using the gleypage of the "Munsell Soil Color Charts" (Kollmor-gen Corporation 1975). (CAUTION: Gleyed con-ditions normally extend throughout saturated soils.Beware of soils with gray E-horizons due to leach-ing and not to saturation; these latter soils can oftenbe recognized by bright-colored layers below theE-horizon.)

B) Other low chroma soils and mottled soils(i.e., soils with low matrix chroma and with orwithout bright mottles) - Hydric mineral soils thatare saturated for substantial periods of the growingseason, but are unsaturated for some time, com-monly develop mottles. Soils that have brightlycolored mottles and a low chroma matrix are indi-cative of a fluctuating water table. Hydric mineralsoils usually have one of the following color fea-tures in the horizon immediately below the A-horizon:

(1) Matrix chroma of 2 or less inmottled soils, or

(2) Matrix chroma of 1 or less in un-mottled soils.

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(Note: See p. 59 for mollisols exception.)

Colors should be determined in soils thatare or have been moistened. The chroma require-ments above are for soils in a moistened condition.Colors noted for dry (unmoistened) soils should beclearly stated as such. The colors of the topsoil areoften not indicative of the hydrologic situation be-cause cultivation and soil enrichment affect theoriginal soil color. Hence, the soil colors below theA-horizon (usually below 10 inches) often must beexamined.

(CAUTION: Beware of problematic hydric soilsthat have colors other than those described above;see problem area wetlands section, p. 55.)

7) Iron and manganese concretions - Duringthe oxidation-reduction process, iron and manga-nese in suspension are sometimes segregated asoxides into concretions or soft masses. Concre-tions are local concentrations of chemical com-pounds (e.g., iron oxide) in the form of a grain ornodule of varying size, shape, hardness, and color(Buckman and Brady 1969). Manganese concre-tions are usually black or dark brown, while ironconcretions are usually yellow, orange or reddishbrown. In hydric soils, these concretions are alsousually accompanied by soil colors describedabove.

8) Coarse-textured or sandy hydric soils -Many of the indicators listed above cannot be ap-plied to sandy soils. In particular, soil color shouldnot be used as an indicator in most sandy soils (seeproblem area wetlands section, p. 55). However,three soil features may be used as indicators of hy-dric sandy soils:

A) High organic matter content in the sur-face horizon - Organic matter tends to accumulateabove or in the surface horizon of sandy soils thatare inundated or saturated to the surface for a sig-nificant portion of the growing season. The mineralsurface layer generally appears darker than the min-eral material immediately below it due to organicmatter interspersed among or adhering to sand par-ticles. (Note: Because organic matter also accumu-lates on upland soils, in some instances it may bedifficult to distinguish a surface organic layer asso-ciated with a wetland site from litter and duff asso-ciated with an upland site unless the species com-position of the organic materials is determined)

B) Dark vertical streaking of subsurface ho-rizons by organic matter - Organic matter is moveddownward through sand as the water table fluctu-ates. This often occurs more rapidly and to a great-er degree in some vertical sections of a sandy soilcontaining high content of organic matter than inothers. Thus, the sandy soil appears verticallystreaked with darker areas. When soil from a dark-er area is rubbed between the fingers, the dark or-ganic matter stains the fingers.

C) Wet Spodosols - As organic matter ismoved downward through some sandy soils, itmay accumulate at the point representing the mostcommonly occurring depth to the water table. Thisorganic matter may become slightly cemented withaluminum. Spodic horizons often occur at depthsof 12 to 30 inches below the mineral surface. Wetspodosols (formerly called "groundwater podzolicsoils") usually have thick dark surface horizonsthat arc high in organic matter with thick, dull grayE-horizons above a very dark-colored (black)spodic horizon. (CAUTION: Not all soils withspodic horizons meet the hydric soil criterion; seep. 58.)

(Note: In recently deposited sandy material,such as accreting sand bars, it may be impossibleto find any of the above indicators. Such cases areconsidered natural, problem area wetlands and thedetermination of hydric soil should be based onknowledge of local hydrology. See p. 57-58).

Wetland Hydrology

3.29. The driving force creating wetlands is "wet-land hydrology", that is, permanent or periodic in-undation, or soil saturation for a significant period(usually a week or more) during the growing sea-son. All wetlands are, therefore, at least periodical-ly wet. Many wetlands are found along rivers,lakes, and estuaries where flooding is likely to oc-cur, while other wetlands form in isolated depres-sions surrounded by upland where surface watercollects. Still others develop on slopes of varyingsteepness, in surface water drainageways or whereground water discharges to the land surface inspring or seepage areas.

3.30. Numerous factors influence the wetness ofan area, including precipitation, stratigraphy, to-pography, soil permeability, and plant cover. The

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frequency and duration of inundation or soil satura-tion are important in separating wetlands from non-wetlands. Duration usually is the more importantfactor. Areas of lower elevation in a floodplain ormarsh have longer duration of inundation and satu-ration and often more frequent periods of theseconditions than most areas at higher levels. Flood-plain configuration may significantly affect the du-ration of inundation by facilitating rapid runoff orby causing poor drainage. Soil permeability relatedto the texture of the soil also influences the durationof inundation or soil saturation. For example, clay-ey soils absorb water more slowly than sandy orloamy soils, and therefore have slower permeabili-ty and remain saturated much longer. Type andamount of plant cover affect both degree of inunda-tion and duration of saturated soil conditions. Ex-cess water drains more slowly in areas of abundantplant cover, thereby increasing duration of inunda-tion or soil saturation. On the other hand, transpira-tion rates are higher in areas of abundant plant cov-er, which may reduce the duration of soilsaturation.

3.31. To determine whether the wetland hydrolo-gy criterion is met, one should consider recordeddata, aerial photographs, and field indicators thatprovide direct or indirect evidence of inundation orsoil saturation.

Recorded Data

3.32. Recorded hydrologic data usually providesboth short- and long-term information on the fre-quency and duration of flooding, but little or no in-formation on soil saturation periods. Recorded datainclude stream gauge data, lake gauge data, tidalgauge data, flood predictions, and historical floodrecords. Use of these data is commonly limited toareas adjacent to streams and other similar areas.Recorded data may be available from the followingsources:

1) CE district offices (data for major waterbod-ies and for site-specific areas from planning anddesign documents)

2) U.S. Geological Survey (stream and tidalgauge data)

3) National Oceanic and Atmospheric Adminis-tration (tidal gauge data)

4) State, county and local agencies (flood data)

5) SCS state offices (small watershed projectsdata)

6) private developers or landowners (site-specific hydrologic data, which may include watertable or groundwater well data).

Aerial Photographs

3.33. Aerial photographs may provide direct evi-dence of inundation or soil saturation in an area. In-undation (flooding or ponding) is best observedduring the early spring in temperate and boreal re-gions when snow and ice are gone and leaves ofdeciduous trees and shrubs are not yet present.This allows detection of wet soil conditions thatwould be obscured by the tree or shrub canopy atfull leaf-out. For marshes, this season of photogra-phy is also desirable, except in regions character-ized by distinct dry and rainy seasons, such assouthern Florida and California. Wetland hydrolo-gy would be best observed during the wet seasonin these latter areas.

3.34. It is most desirable to examine several con-secutive years of early spring or wet season aerialphotographs to document evidence of wetland in-undation or soil saturation. In this way, the effectsof abnormally dry springs, for example, may beminimized. In interpreting aerial photographs, it isimportant to know the antecedent weather condi-tions. This will help eliminate potential misinterpre-tations caused by abnormally wet or dry periods.Contact the U.S. Weuther Service for historicalweather records. Aerial photographs for agricultu-ral regions of the country are often available atcounty offices of the Agricultural Stabilization andConservation Service.

Field Indicators

3.35. At certain times of the year in most wet-lands, and in certain types of wetlands at mosttimes, wetland hydrology is quite evident, sincesurface water or saturated soils (e.g., soggy orwetter underfoot) may be observed. Yet in manyinstances, especially along the uppermost boundaryof wetlands, hydrology is not readily apparent.Consequently, the wetland hydrology criterion is

16

often impracticable for delineating precise wetlandboundaries. Despite this limitation, hydrologic in-dicators can be useful for confirming that a sitewith hydrophytic vegetation and hydric soils stillexhibits wetland hydrology and that the hydrologyhas not been significantly modified to the extentthat the area is now effectively drained. In otherwords, while hydrologic indicators are sometimesdiagnostic of the presence of wetlands, they aregenerally either operationally impracticable (e.g., inthe case of recorded data) or technically inaccurate(e.g., in the case of some field indicators) for de-lineating wetland boundaries. In the former case,surveying the wetland boundary according to ele-vation data related to recorded flood data, for ex-ample, is generally too time-consuming and maynot actually be a true correlation. In the latter case,it should be quite obvious that indicators of flood-ing often extend well beyond the wetland boundaryinto low-lying upland areas that were flooded by aninfrequent flood. Consequently the emphasis ondelineating wetland boundaries should be placed onhydrophytic vegetation and hydric soils in the ab-sence of significant hydrologic modification, al-though wetland hydrology should always be con-sidered.

3.36. If significant drainage or groundwater alter-ation has taken place, then it is necessary to deter-mine whether the area in question is effectivelydrained and is now nonwetland or is only partlydrained and remains wetland despite some hydro-logic modification. Guidance for determiningwhether an area is effectively drained is presentedin the section on disturbed areas (p. 50). In the ab-sence of visible evidence of significant hydrologicmodification, wetland hydrology is presumed tooccur in an area having hydrophytic vegetation andhydric soils.

3.37. The following hydrologic indicators can beassessed quickly in the field. Although some arenot necessarily indicative of hydrologic events dur-ing the growing season or in wetlands alone, theydo provide evidence that inundation or soil satura-tion have occurred at some time. One should usegood professional judgement in deciding whetherthe hydrologic indicators demonstrate that the wet-land hydrology criterion has been satisfied. Whenconsidering these indicators, it is important to beaware of recent extreme flooding events and heavyrainfall periods that could cause low-lying nonwet-lands to exhibit some of these signs. It is, there-fore, best to avoid, if possible, field inspections

during and immediately after these events. If notpossible, then these events must be considered inmaking a wetland determination. Also, rememberthat hydrology varies seasonally and annually aswell as daily, and that at significant times of theyear (e.g., late summer for most of the country) thewater tables are at their lowest points. At these lowwater periods, signs of soil saturation and floodingmay be difficult to find in many wetlands.

1) Visual observation of inundation - The mostobvious and revealing hydrologic indicator may besimply observing the areal extent of inundation.However, both seasonal conditions and recentweather conditions should be considered when ob-serving an area because they can affect whethersurface water is present on a nonwetland site.

2) Visual observation of soil saturation - Insome cases, saturated soils are obvious, since theground surface is soggy or mucky under foot. Inmany cases, however, examination of this indicatorrequires digging a hole to a depth of 18 inches andobserving the level at which water stands in thehole after sufficient time has been allowed for wa-ter to drain into the hole. The required time willvary depending on soil texture. In some cases, theupper level at which water is flowing into the holecan be observed by examining the wall of the hole.This level represents the depth to the water table.The depth to saturated soils will always be nearerthe surface due to a capillary fringe. In some heavyclay soils, water may not rapidly accumulate in thehole even when the soil is saturated. If water is ob-served at the bottom of the hole but has not filled tothe 12-inch depth, examine the sides of the holeand determine the shallowest depth at which wateris entering the hole. Saturated soils may also be de-tected by a "squeeze test," which involves taking asoil sample within 18 inches (actual depth dependson soil permeability) and squeezing the sample. Iffree water can be extracted, the soil is saturated atthe depth of the sample at this point in time. Whenapplying the soil saturation indicator, both the sea-son of the year and the preceding weather condi-tions must be considered, (Note: It is not necessaryto directly demonstrate soil saturation at the time ofinspection. If the NTCHS criteria for hydric soilare met, it can be assumed that an area is saturatedto the surface or inundated at some point in timeduring an average rainfall year.)

3) Oxidized channels (rhizospheres) associatedwith living roots and rhizomes - Some plants are

17

able to survive saturated soil conditions (i.e., a re-ducing environment) because they can transport ox-ygen to their root zone. Look for iron oxide concre-tions (orangish or reddish brown in color) formingalong the channels of living roots and rhizomes asevidence of soil saturation (anaerobic conditions)for a significant period during the growing season.

4) Water marks - Water marks are found mostcommonly on woody vegetation but may also beobserved on other vegetation. They often occur asstains on bark or other fixed objects (e.g., bridgepillars, buildings, and fences). When several watermarks are present, the highest usually reflects themaximum extent of recent inundation.

5) Drift lines - This indicator is typically foundadjacent to streams or other sources of water flowin wetlands and often occurs in tidal marshes. Evi-dence consists of deposition of debris in a line onthe wetland surface or debris entangled in above-ground vegetation or other fixed objects. Debrisusually consists of remnants of vegetation (branch-es, stems, and leaves), sediment, litter, and otherwater-borne materials deposited more or less paral-lel to the direction of water flow. Drift lines providean indication of the minimum portion of the area in-undated during a flooding event; the maximum lev-el of inundation is generally at a higher elevationthan that indicated by a drift line.

6) Water-borne sediment deposits - Plants andother vertical objects often have thin layers, coat-ings, or depositions of mineral or organic matter onthem after inundation. This evidence may remainfor a considerable period before it is removed byprecipitation or subsequent inundation. Sedimentdeposition on vegetation and other objects providesan indication of the minimum inundation level.When sediments are primarily organic (e.g., fineorganic material and algae), the detritus may be-come encrusted on or slightly above the soil surfaceafter dewatering occurs.

7) Water-stained leaves - Forested wetlandsthat are inundated earlier in the year will frequentlyhave water-stained leaves on the forest floor. Theseleaves are generally grayish or blackish in appear-ance, darkened from being underwater for signifi-cant periods.

8) Surface scoured areas - Surface scouring oc-curs along floodplains where overbank floodingerodes sediments (e.g., at the bases of trees). The

absence of leaf litter from the soil surface is alsosometimes an indication of surface scouring. Fo-rested wetlands that contain standing waters for rel-atively long duration will occasionally have areas ofbare or essentially bare soil, sometimes associatedwith local depressions.

9) Wetland drainage patterns - Many wetlands(e.g., tidal marshes and floodplain wetlands) havecharacteristic meandering or braided drainage pat-terns that are readily recognized in the field or onaerial photographs and occasionally on topographicmaps. (CAUTION: Drainage patterns also occur inupland areas after periods of considerable precipita-tion; therefore, topographic position also must beconsidered when applying this indicator.)

10) Morphological plant adaptations - Manyplants growing in wetlands have developed mor-phological adaptations in response to inundation orsoil saturation. Examples include pneumatophores,buttressed tree trunks, multiple trunks, adventitiousroots, shallow root systems, floating stems, float-ing leaves, polymorphic leaves, hypertrophied len-ticels, inflated leaves, stems or roots, and aeren-chyma (air-filled) tissue in roots and stems (seeTable 1 for examples). As long as there is no evi-dence of significant hydrologic modification, theseadaptations can be used as hydrologic indicators.Moreover, when these features are observed inyoung plants, they provide good evidence that re-cent wetland hydrology exists. (Note: While somepeople may consider these morphological adapta-tions as indicators of hydrophytic vegetation, forpurposes of this manual, they are treated as indica-tors of wetland hydrology because they typicallydevelop in response to permanent or periodic inun-dation or soil saturation.)

11) Hydric soil characteristics - In the absenceof the above indicators, if an area meets the field in-dicators for hydric soils and there is no indicationof significant hydrologic modification, then it canbe assumed that the area meets the wetland hydrol-ogy criterion. If the area has been significantly dis-turbed hydrologically, refer to the section on dis-turbed areas (p. 50). (CAUTION: Listing of a soilon the NTCHS list of hydric soils does not neces-sarily mean the wetland hydrology criterion is met,nor does exclusion of a soil from the list demon-strate that the wetland hydrology criterion has notbeen met. However, soils on the NTCHS list rep-resent those soils which typically meet the wetlandhydrology criterion, unless effectively drained orotherwise altered.)

18

Table 1. Morphological or structural adaptations of plants for growingIn permanently or periodically flooded or saturated soils.

Adaptations

Buttressed (swollen)Tree Trunk

Multiple Trunks

Pneumataphores

Adventitious Roots(arising from stem aboveground)

Shallow Roots (oftenexposed to ground surface)

Hypertrophied Lenticels

Aerenchyma (air-filledtissue) in Roots & Stems

Polymorphic Leaves

Floating Leaves

Examples of Plants Possessing Adaptation

Bald Cypress (Taxodium distichum), Black Gum(Nyssa sylvatica var. biflora), Green Ash (Fraxinus pennsylvan-ica var. subintegerima), Water Gum (Nyssa aquatica), andOgechee Tupelo (Nyssa ogechee)

Red Maple (Acer rubrum), Silver maple (Acer saccharinum),Swamp Privet (Forestiera acuminata), and Ogechee Tupelo

Bald Cypress, Water Gum, and Black Mangrove (Rhizophoramangle)

Box Elder (Acer negundo), Sycamore (Platanusoccidentalis), Pin Oak (Quercus palustris),Black Willow (Salix nigra), Green Ash, Alligatorweed (Alter-nanthera philoxeroides), Water Primroses (Ludwigia spp.),Water Gum, Eastern Cottonwood (Populus deltoides), and Wil-lows (Sa//xspp.)

Red Maple and Laurel Oak (Quercus laurifolia)

Red Maple, Silver Maple, Willows, Black Mangrove, Water Lo-cust (Gleditsia aquatica), and Sweet Gale (Myrica gale)

Eastern Bur-reed (Sparganium americanum),Soft Rush (Juncus effusus), Soft-stemmed Bulrush (Scirpusvalidus), Water Shield (Brasenia schreberi), Umbrella Sedges(Cyperusspp.), other Rushes (Juncus spp.), Spike-rushes(Eleocharis spp.), Twig-rush (Cladium mariscoides), Buckbean(Menyanthes trifoliata), Giant Bur-reed (Sparganium eurycar-pum), and Cattails (Typha spp.)

Arrowheads (Sagittaria spp.) and Water Parsnip (Slum suave)

Water Shield, Spatterdock Lily (Nuphar luteum), and WhiteWater Lily (Nymphaea odorata)

Sources: Environmental Laboratory (1987) and Tiner (1988).

19

20

Part IV.Methods for Identifica-tion and Delineation ofWetlands

4.0. Four basic approaches for identify-ing and delineating wetlands have beendeveloped to cover situations rangingfrom desk-top or office determinationsto highly complex field determinationsfor regulatory purposes. These methods

are the recommended approaches and the reasonsfor departing from them should be documented.Remember, however, that any method for making awetland determination must consider the three tech-nical criteria (i.e., hydrophytic vegetation, hydricsoils, and wetland hydrology) listed in Part II ofthis manual. These criteria must be met in order toidentify a wetland. In applying all methods, rele-vant available information on wetlands in the areaof concern should be collected and reviewed. Table2 lists primary data sources.

Selection of a Method

4.1. The wetland delineation methods presented inthis manual can be grouped into two general types:(1) off site procedures and (2) onsite procedures.The offsite procedures are designed for use in theoffice, while onsite procedures are developed foruse in the field. When an onsite inspection is unne-cessary or cannot be undertaken for various rea-sons, available information can be reviewed in theoffice to make a wetland determination. If availableinformation is insufficient to make a wetland deter-mination or if a precise wetland boundary must beestablished, an onsite inspection should be con-ducted. Depending on the field information neededor the complexity of the area, one of three basiconsite methods may be employed: (1) routine, (2)intermediate-level, or (3) comprehensive.

4.2. The routine method is designed for areasequal to or less than five acres in size or larger are-as with homogeneous vegetation. For areas greaterthan five acres in size or other areas of any size thatare highly diverse in vegetation, the intermediate-level method or the comprehensive method shouldbe applied, as necessary. The comprehensive meth-od is applied to situations requiring detailed docu-mentation of vegetation, soils, and hydrology.Assessments of significantly disturbed sites willoften require intermediate-level or comprehensivedeterminations as well as some special procedures.In other cases where natural conditions make wet-land identification difficult, special procedures forproblem area wetland determinations have beendeveloped. These procedures are subroutines of thethree onsite determination methods. In making wet-land determinations, one should select the appro-priate method for each individual unit within thearea of concern and not necessarily employ onemethod for the entire site. Thus, a combination ofdetermination methods may be used for a givensite.

4.3. Regardless of the method used, the desiredoutcome or final product is a wetland/nonwetlanddetermination. Depending on one's expertise,available information, and individual or agencypreference, there are two basic approaches to delin-eating wetland boundaries. The first approachinvolves characterizing plant communities in thearea, identifying hydrophytic plant communities,examining the soils in these areas to confirm thepresence of hydric soil, and finally looking for evi-dence of wetland hydrology. This approach hasbeen widely used by the CE and EPA and to a largeextent by the FWS. A second approach involvesfirst delineating the boundary of hydric soils, andthen verifying the presence of hydrophytic vegeta-tion and looking for signs of wetland hydrology.This type of approach has been employed by theSCS and to a limited extent by the FWS. Sincethese approaches yield the same result, this manualincorporates both approaches into most of themethods presented.

21

Table 2. Primary sources of information that may be helpfulin making a wetland determination.

Data Name

Topographic Maps (mostly 1:24,000;1:63,350 for Alaska)National Wetlands Inventory Maps(mostly 1:24,000; 1:63,350for Alaska)

County Soil Survey Reports

National Hydric Soils ListState Hydric Soils ListCounty Hydric Soil Map Unit ListNational Insurance AgencyFlood Maps

Local Wetland Maps

Land Use and Land Cover Maps

Aerial Photographs

Satellite Imagery

National List of Plant SpeciesThat Occur in Wetlands(Stock No. 024-010-00682-0)

Regional Lists of Plants thatOccur in Wetlands

National Wetland Plant Database

Stream Gauge Data

Soil Drainage GuidesEnvironmental Impact Statementsand AssessmentsPublished Reports

Local Expertise

Site-specific Plans andEngineering Designs

Source

U.S. Geological Survey (USGS)(Call 1-800-USA-M APS)U.S. Fish and Wildlife Service(FWS) (Call 1-800-USA-M APS)

U.S.D.A. Soil Conservation Service (SCS) District Offices(Unpublished reports-local district offices)SCS National OfficeSCS State OfficesSCS District OfficesFederal Emergency ManagementAgency

State and local agencies

USGS (1-800-USA-MAPS)

Various sources-USGS, U.S.D.A. Agricultural Stabilization andConservation Service, other Federal and State agencies, and pri-vate sources

EOSAT Corporation, SPOT Corporation, and others

Government Printing OfficeSuperintendent of DocumentsWashington, DC 20402

National Technical Information Service5285 Port Royal HeadSpringfield, VA22161(703) 487-4650

FWS

CE District Offices and USGS

SCS District OfficesVarious Federal and State agencies

Federal and States agencies, universities, and others

Universities, consultants, and others

Private developers

22

Description of Methods

Offsite Determinations

4.4. When an onsite inspection is not necessarybecause information on hydrology, hydric soils,and hydrophytic vegetation is known or an inspec-tion is not possible due to time constraints or otherreasons, a wetland determination can be made inthe office. This approach provides a best approxi-mation of the presence of wetland and its bounda-ries based on available information. The accuracyof the determination depends on the quality of theinformation used and on one's ability and experi-ence in an area to interpret these data. Where relia-ble, site-specific data have been previously collect-ed, the wetland determination should be reasonablyaccurate. Where these data do not exist, more gen-eralized information may be used to make a prelim-inary wetland determination. In either case, howev-er, if a more accurate delineation is required, thenonsite procedures must be employed.

Offsite Determination Method

4.5. The following steps are recommended forconducting an offsite wetiand determination:

Step 1. Locate the area of interest on aU.S.Geological Survey topographic map anddelineate the approximate subject area boundary onthe map. Note whether marsh or swamp symbolsor lakes, ponds, rivers, and other waterbodies arepresent within the area. If they are, then there is agood likelihood that wetland is present. Proceed toStep 2.

Step 2. Review appropriate National Wet-lands Inventory (NWI) maps, State wetland maps,or local wetland maps, where available. If thesemaps designate wethnds in the subject area, thereis a high probability that wetlands are presentunless there is evidence on hand that the wetlandshave been effectively drained, filled, excavated,impounded, or otherwise significantly altered sincethe effective date of the maps. Proceed to Step 3.

Step 3. Review SCS soil survey mapswhere available. In the area of interest, are thereany map units listed on the county list of hydricsoil map units or are there any soil map units withsignificant hydric soil inclusions? If YES, thenassume that at least a portion of the project area

may be wetland. If this area is also shown as awetland on NWI or other wetland maps, then thereis a high probability that the area is wetland unlessit has been recently altered (check recent aerial pho-tos, Step 4). Areas without hydric soils or hydricsoil inclusions should in most cases be eliminatedfrom further review, but aerial photos still shouldbe examined for small wetlands to be more certain.This is especially true if wetlands have been desig-nated on the National Wetlands Inventory or otherwetland maps. Proceed to Step 4.

Step 4. Review recent aerial photos of theproject area. Before reviewing aerial photos, evalu-ate climatological data to determine whether thephoto 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 pro-vide a useful perspective or frame-of-reference fordoing photo interpretation. In some cases, aerialphotos covering a multi-year period (e.g., 5-7years) should be reviewed, especially where recentclimatic conditions have been abnormal.

During photo interpretation, look for one or moresigns of wetlands. For example:

1) hydrophytic vegetation;2) surface water,3) saturated soils;4) flooded or drowned out crops;5) stressed crops due to wetness;6) greener crops in dry years;7) differences in vegetation patterns due todifferent planting dates.

If signs of wetland are observed, proceed to Step 5when site-specific data are available; if site-specificdata are not available, proceed to Step 6.

(CAUTION: Accurate photo interpretation of cer-tain wetland types requires considerable expertise.Evergreen forested wetlands and temporarily flood-ed wetlands, in general, may present considerabledifficulty. If not proficient in wetland photo inter-pretation, then one can rely more on the findings ofother sources, such as NWI maps and soil sur-veys, or seek help in photo interpretation.)

Step 5. Review available site-specific infor-mation. In some cases, information on vegetation,soils, and hydrology for the project area has beencollected during previous visits to the area by agen-cy personnel, environmental consultants or others.

23

Moreover, individuals or experts having firsthandknowledge of the project site should be contactedfor information whenever possible. Be sure, how-ever, to know the reliability of these sources. Afterreviewing this information, proceed to Step 6.

Step 6. Determine whether wetlands exist inthe subject area. Basec' on a review of existinginformation, wetlands can be assumed to exist if:

1) Wetlands are shown on NWI or otherwetland maps, and hydri'j soil or a soil with hydricsoil inclusions is shown on the soil survey; or

2) Hydric soil or soil with hydric soil inclu-sions is shown on the SOT! survey, and

A) site-specific information confirmshydrophytic vegetation, hydric soils, and/or wet-land hydrology, or

B) signs of wetland are detected byreviewing aerial photos; or

3) Any combination of the above or partsthereof (e.g., vegetated wetland on NWI maps andsigns of wetland on aerial photos).

If after examining the available referencematerial one is still unsure whether wetland occursin the area, then a field inspection should be con-ducted, whenever possible. Alternatively, more

detailed information on the site characteristics maybe sought from the project sponsor, if applicable, tohelp make the determination.

4.6. Offsite procedures arc dependent on the avail-ability of information for making a wetland determi-nation, the quality of this information, and one'sability and experience to interpret these data. Inmost cases, therefore, the offsite procedure yields apreliminary determination. For more accurateresults, one must conduct an onsite inspection.

Onsite Determinations

4.7. When an onsite inspection is necessary, besure to review pertinent background information(e.g., NWI maps, soil surveys, and site plans)before going to the subject site. This informationwill be helpful in determining what type of fieldmethod should be employed. Also, read the sec-tions of this manual that discuss disturbed andproblem area wetlands before conducting field work(see p. 50-59). Recommended equipment and mate-rials for conducting onsite determinations are listedin Table 3.

Figures 1, 2, and 3 show the conceptual approachesfor making onsite wetland determinations. Thesefigures are NOT decision matrices for making wet-land determinations.

Table 3. Recommended equipment and materials for onsite determinations.

Equipment

Soil auger, probe, or spadeSighting compassPen or pencilPenknifeHand lensVegetation sampling frame*Camera/FilmBinocularsTape measurePrism or angle gaugeDiameter tape*Vasculum (for plant collection)Calculator*Dissecting kit

Materials

Data sheets and clipboardField notebookBase (topographic) mapAerial photographNational Wetlands Inventory mapSoil survey or other soil mapAppropriate Federal interagency wetland plants listCounty hydric soil map unit listMunsell scoil color bookPlant identification field guides/manualsNational List of Scientific Plant NamesFlagging tape/wire flags/wooden stakesPlastic bags (for collecting plants and soil samples as needed)

* Needed for comprehensive determination

24

¥ECETATI

ON

OBL.FACW. AND/OR FACSPECIES COMPRISE ,50%

OFTHEDOMMANTSOR

PL AHT COMMUNITY HASA PREVALENCE MOCX O.O

HYORIC SOL PRESENT, Md Mlceurs

entoc xill wilted ••on Hydrlc Sons LIU)

JURISDICTIONALWETLAND

OBL. FACW, AND/OR FACCOMPRISE *2i% AND i5O* OF

DOMINANT PLANT SPECIESOR

PLANT COMMUNITY HASA PREVALENCE INDEX

>3.S AND j4.0

HTOflIC SOU. PRESENT

(•.g.. IMd Indktlort ind/or tollv«rl««l •> on Hydlk SoU> Llll)

It ltl«r« dlroct »vld«nca olInundvHon or »H Mturatlonwithin 6-11 IncnM during th«growing *MMn (t.g., directobMnretton*. eerlel pheto*.

or other reUebl* eourcee). ereoildlled chennelt present

ehtng Hying root* end rtlliomes,or ere weter-irelned leeve*due 10 Inundetion present?

Indlceton. check proouieeree weDend* end

disturbed erees discussions,end use best proleeslOAel

lodgement to meke wenend

Figure 1. Composite of Conceptual Approaches for Making anOnsite Jurisdctonal Wetland Delerminalron.(CAUTION- This is NOT a Decision Matrix for Makinga Wetland Determination.)

25

NONWETLANDCheck problem

area wetlands anddisturbed areas

discussions, and UM bestprofessional judgement to

make wetland determination;consult experts II

necessary

OBL, FACW, AND/OR FACSPECIES COMPRISE Z25% TOi50% OF THE DOMINANTS

OBL, FACW, AND/OR FACSPECIES COMPRISE >50%

OF THE DOMINANTS

JURISDICTIONALWETLAND

HYDRtC SOIL PRESENT

AREA MEETS OHPOSSIBLY MEETS

HYDRIC SOIL CRITERION

NONWETLAND

AREA MEETS ORPOSSIBLY MEETS

WETLAND HYDROLOGYCRITERION

PREVALENCE INDEX»3.0 TO *3.5

PREVALENCE INDEX3.5 AND » dlracl evidence olinundation or toll eaturallonwithin 6-18 inch** during thegrowing ••••on (e.g., directobservations, a*ri«l photo*,

or othar rftliabl* •ourcca),oxidized etwiiwl* prM«nl

•long living root* mnd rhixonw*.wator-«taln«d !MV»

du« to Inundation pr«E«nt?

YES

dl*cu«*lon«, and us* tw«tproltMkmal |udg«m*nt to

n»Jw mtland determination

JURISDICT1ONALWETLAND

Flgur* 3. Conceptual Flow Chart Using Frequency Analysis(Point Intercept Sampling Procedures) otVegetation in Making an Onsile JurisdictionalDetermination. {CAUTION: This is NOT a DecisionMatrix lor Making a Wetland Determination.)

29

4.8. For every upcoming field inspection, the fol-lowing pre-inspection steps should be undertaken:

Step 1. Locate the project area on a map(e.g., U.S. Geological Survey topographic map orSCS soil survey map) or on an aerial photographand determine the limits of the area of concern.Proceed to Step 2.

Step 2. Estimate the size of the subject area.Proceed to Step 3.

Step 3. Review existing background infor-mation and determine, to the extent possible, thesite's geomorphological setting (e.g., floodplain,isolated depression, or ridge and swale complex),its habitat or vegetative complexity (i.e., the rangeof habitat or vegetation types), and its soils. (Note:Depending on available information, it may not bepossible to determine the habitat complexity with-out going on the site; if necessary, do a field recon-naissance.) Proceed to Step 4.

Step 4. Determine whether a disturbed con-dition exists. Examine available information anddetermine whether there is evidence of sufficientnatural or human-induced alteration to significantlymodify all or a portion of the area's vegetation,soils, and/or hydrology. If such disturbance is not-ed, identify the limits of affected areas for theyshould be evaluated separately for wetland determi-nation purposes (usually after evaluating undis-turbed areas). The presence of disturbed areaswithin the subject area should be considered whenselecting an onsite determination method. (Note: Itmay be possible that at any time during this deter-mination, one or more of the three characteristicsmay be found to be significantly altered. If thishappens, follow the disturbed area wetland deter-mination procedures, as necessary, noted on p.50.) Proceed to Step 5.

Step 5. Determine the field determinationmethod to be used. Considering the size and com-plexity of the area, determine whether a routine,intermediate-level, or comprehensive field determi-nation method should be used. When the area isequal to or less than five acres in size or is largerand appears to be relatively homogeneous withrespect to vegetation, soils, and/or hydrology, usethe routine method (see below). When the area isgreater than five acres in size, or