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(continued) inundation. The user must relate the observed species to other similar situations and determine whether they are normally found in wet areas, taking into consideration the season and immediately preceding weather conditions. If you encounter this situation, you may be dealing with an atypical situation or a problem area.

(ii) Morphological adaptations. Some hydrophytic species have easily recognized physical characteristics that indicate their ability to occur in wetlands. A given species may exhibit several of these characteristics, but not all hydrophytic species have evident morphological adaptations.

(iii) Technical literature. The technical literature may provide a strong indication that plant species comprising the prevalent vegetation are commonly found in areas where soils are periodically saturated for long periods. Sources of available literature include:

(A) Taxonomic references. Such references usually contain at least a general description of the habitat in which a species occurs. A habitat description such as, "Occurs in water of streams and lakes and in alluvial floodplains subject to periodic flooding," supports a conclusion that the species typically occurs in wetlands.

(B) Botanical journals. Some botanical journals contain studies that define species occurrence in various hydrologic regimes.

(C) Technical reports. Governmental agencies periodically publish reports (e.g., literature reviews) that contain information on plant species occurrence in relation to hydrologic regimes.

(D) Technical workshops, conferences, and symposia. Publications resulting from periodic scientific meetings contain valuable information that can be used to support a decision regarding the presence of hydrophytic vegetation. These usually address specific regions or wetland types.

(E) Wetland plant data base. The National Wetland Inventory has produced a Plant Data Base that contains habitat information on over 6,700 plant species that occur at some estimated probability in wetlands, as compiled from the technical literature.

(iv) Physiological adaptations. Physiological adaptations include any features of the metabolic processes of plants that make them particularly fitted for life in saturated soil conditions. NOTE: It is impossible to detect the presence of physiological adaptations in plant species during on-site visits.

(v) Reproductive adaptations. Some plant species have reproductive features that enable them to become established and grow in saturated soil conditions.

(6) Hydric soils. Indicators. Indicators are listed in descending order of reliability. Although all are valid indicators, some are stronger indicators than others. When a decision is based on an indicator appearing in the lower portion of the list, re-evaluate the parameter to ensure that the proper decision was reached.

A hydric soil may be either drained or undrained, and a drained hydric soil may not continue to support hydrophytic vegetation. Therefore, not all areas having hydric soils will qualify as wetlands. Only when a hydric soil supports hydrophytic vegetation and the area has indicators of wetland hydrology may the area be referred to as a wetland.

A drained hydric soil is one in which sufficient ground or surface water has been removed by artificial means such that the area will no longer support hydrophytic vegetation or wetland hydrology. On-site evidence of drained soils includes:

(a) Presence of ditches or canals of sufficient depth to lower the water table below the major portion of the root zone of the prevalent vegetation.

(b) Presence of dikes, levees, or similar structures that obstruct normal inundation of an area.

(c) Presence of a tile system to promote subsurface drainage.

(d) Diversion of upland surface run-off from an area.

Although it is important to record such evidence of drainage of an area, a hydric soil that has been drained or partially drained still allows the soil parameter to be met. However, the area will not qualify as a wetland if the degree of drainage has been sufficient to preclude the presence of either hydrophytic vegetation or a hydrologic regime that occurs in wetlands. NOTE: The mere presence of drainage structures in an area is not sufficient basis for concluding that a hydric soil has been drained; such areas may continue to have wetland hydrology.

(7) Indicators of hydric soils (nonsandy soils). Several indicators are available for determining whether a given soil meets the definition and criteria for hydric soils. Any one of the following indicates that hydric soils are present.

(a) Organic soils (Histosols). As a general rule, a soil is an organic soil when:

(i) More than 50 percent (by volume) of the upper 32 inches of soil is composed of organic soil material; or

(ii) Organic soil material of any thickness rests on bedrock. Organic soils are saturated for long periods and are commonly called peats or mucks.

(b) Histic epipedons. A histic epipedon is an 8-inch to 16-inch layer at or near the surface of a mineral hydric soil that is saturated with water for 30 consecutive days or more in most years and 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 inundated or saturated for sufficient periods to greatly retard aerobic decomposition of the organic surface, and are considered to be hydric soils.

(c) Sulfidic material. When mineral soils emit an odor of rotten eggs, hydrogen sulfide is present. Such odors are only detected in soils that are permanently saturated and have sulfidic material within a few centimeters of the soil surface. Sulfides are produced only in a reducing environment.

(d) Aquic or peraquic moisture regime. An aquic moisture regime is a reducing one; i.e., it is virtually free of dissolved oxygen because the soil is saturated by ground water or by water of the capillary fringe. Because dissolved oxygen is removed from ground water by respiration of microorganisms, roots, and soil fauna, it is also implicit that the soil temperature is above biologic zero (41°F at 20 inches) at the same time the soil is saturated. Soils with peraquic moisture regimes are characterized by the presence of ground water which is always at or near the soil surface and exhibits reducing conditions. Examples include soils of tidal marshes and soils of closed, landlocked depressions that are fed by permanent streams.

(e) Reducing soil conditions. Soils saturated for long or very long duration will usually exhibit reducing conditions. Under such conditions, ions of iron are transformed (reduced) from a ferric valence state (Fe3) to a ferrous valence state (Fe2). This condition can often be detected in the field by a ferrous iron test. A simple colorimetric field test kit has been developed for this purpose. When a soil extract changes to a pink color upon addition of alpha-alpha-dipyridil, ferrous iron is present, which indicates a reducing soil environment. NOTE: This test cannot be used in mineral hydric soils having low iron content, organic soils, and soils that have been desaturated for significant periods of the growing season. Caution: This test can only be used as a positive indicator of reducing conditions and it is only effective if it is done at the time that a mineral soil is actively reducing. While the presence of a reaction indicates anaerobic conditions, the lack of a reaction does not indicate a lack of anaerobic conditions.

(f) Soil colors. The colors of various soil components are often the most diagnostic indicator of hydric soils. Colors of these components are strongly influenced by the frequency and duration of soil saturation, which leads to reducing soil conditions. Mineral hydric soils will be either gleyed or will have contrasting mottles and/or low chroma matrix. These are discussed below:

NOTE: Soil terminology is undergoing constant change, and terms such as "mottles" and "low chroma colors" are being replaced with the term "redoximorphic features." In order to retain consistency with the Corps 1987 Manual, the older terms are used below.

(i) Gleyed soils (gray colors). Gleyed soils develop when anaerobic soil conditions result in pronounced chemical reduction of iron, manganese, and other elements, thereby producing gray soil colors. Anaerobic conditions that occur in waterlogged soils result in the predominance of reduction processes, and such soils are greatly reduced. Iron is one of the most abundant elements in soils. Under anaerobic conditions, iron in converted from the oxidized (ferric) state to the reduced (ferrous) state, which results in the bluish, greenish, or grayish colors associated with the gleying effect. Gleying immediately below the A-horizon or 10 inches (whichever is shallower) is an indication of a markedly reduced soil, and gleyed soils are hydric soils. Gleyed soil conditions can be determined by using the gley page of the Munsell Color Charts (Munsell Color 1990).

(ii) Soils with contrasting mottles and/or low chroma matrix. Mineral hydric soils that are saturated for substantial periods of the growing season (but not long enough to produce gleyed soils) will either have high chroma mottles and a low chroma matrix or will lack mottles but have a low matrix chroma. Mottled means "marked with spots of contrasting color." Soils that have high chroma mottles and a low chroma matrix are indicative of a fluctuating water table.

NOTE: Hydric soils can also have low chroma mottles that contrast with the matrix color.

The soil matrix is the portion (usually more than 50 percent) of a given soil layer that has the predominant color. Colors should be determined in soils that have been moistened; otherwise, state that colors are for dry soils. Mineral hydric soils usually have one of the following color features in the horizon immediately below the A-horizon or 10 inches (whichever is shallower):

(A) Matrix chroma of 2 or less in mottled soils.

(B) Matrix chroma of 1 or less in unmottled soils.

NOTE: The matrix chroma of some dark (black) mineral hydric soils (e.g., Aquolls) will not conform to the criteria described in (f)(ii)(A) and (B) of this subsection; in such soils, gray mottles occurring at 10 inches or less are indicative of hydric conditions. Mollisols that are not hydric will often still have dark colored surface soils.

CAUTION: Soils with significant coloration due to the nature of the parent material may not exhibit the above characteristics. In such cases, this indicator cannot be used.

(g) Soil appearing on hydric soils list. Using the criteria for hydric soils, the NTCHS has developed a list of hydric soils. Listed soils have reducing conditions for a significant portion of the growing season in a major portion of the root zone and are frequently saturated within 12 inches of the soil surface if they have not been effectively drained. CAUTION: Do not use this indicator unless you have field verified that the profile description of the mapping unit conforms to that of the sampled soil.

(h) Iron and manganese concretions. During the oxidation-reduction process, iron and manganese in suspension are sometimes segregated as oxides into concretions, nodules or soft masses. These accumulations are usually black or dark brown. Concretions >2 mm. in diameter occurring within 7.5 cm. of the surface are evidence that the soil is saturated for long periods near the surface.

CAUTION: Concretions may be relict features. Be careful to confirm that the hydrologic conditions that created the concretions still exist before using this indicator.

(8) Additional indicators of hydric soils (for sandy soils). Not all indicators listed above can be applied to sandy soils. In particular, soil color may not be a reliable indicator in most sandy soils. However, three additional soil features may be used as indicators of sandy hydric soils, including:

(a) High organic matter content in the surface horizon. Organic matter tends to accumulate above or in the surface horizon of sandy soils that are inundated or saturated to the surface for a significant portion of the growing season. Prolonged inundation or saturation creates anaerobic conditions that greatly inhibit decomposition (oxidation) of organic matter.

(b) Streaking of subsurface horizons by organic matter. Organic matter is moved downward through sand as the water table fluctuates. This often occurs more rapidly and to a greater degree in some vertical sections of a sandy soil containing a higher content of organic matter than in others. Thus, the sandy soil appears streaked with darker areas. When soil from a darker area is rubbed between the fingers, the organic matter stains the fingers.

(c) Organic pans. As organic matter is moved downward through sandy soils, it tends to accumulate at the point representing the most commonly occurring depth to the water table. This organic matter tends to become slightly cemented with iron and aluminum, forming a thin layer of hardened soil (spodic horizon). These horizons often occur at depths of 12 to 30 inches below the mineral surface. Wet spodic soils usually have thick dark surface horizons that are high in organic matter with dull, gray horizons above the spodic horizon. Generally, the nearer to the surface the spodic horizon, the more likely the soil is hydric.

CAUTION: In recently deposited sandy material (e.g., accreting sandbars), it may be impossible to find any of these indicators. In such cases, consider this a problem area (Entisols).

NOTE: The NRCS developed and published Field Indicators of Hydric Soils in the United States in July 1996. This document includes many useful indicators of hydric soils, however, some hydric soils will lack one of the indicators included in the NRCS document. Therefore, the indicators are only used as positive indicators -- if one or more of the indicators is present, the soil is a hydric soil, but the lack of any of these indicators does not mean the soil is nonhydric. In addition, the Corps has not authorized the use of these new field indicators and has stated that while they may be used as additional information, they do not replace the indicators in the 1987 Manual nor may they be used to contradict the 1987 Manual indicators.

(9) Wetland hydrology. The term "wetland hydrology" encompasses all hydrologic characteristics of areas that are periodically inundated or have soils saturated to the surface at some time during the growing season. Areas with evident characteristics of wetland hydrology are those where the presence of water has an overriding influence on characteristics of vegetation and soils due to anaerobic and chemically reducing conditions, respectively. Such characteristics are usually present in areas that are inundated or have soils that are saturated to the surface for sufficient duration to develop hydric soils and support vegetation typically adapted for life in periodically anaerobic soil conditions. Hydrology is often the least exact of the parameters, and indicators of wetland hydrology are sometimes difficult to find in the field. However, it is essential to establish that a wetland area is periodically inundated or has saturated soils during the growing season.

It is usually impractical to accurately measure the duration of soil saturation in the field because it takes repeated visits over a lengthy (several years) period of time. However, there has been a sufficient amount of research to support that the field indicators provided in the manual and supplementary guidance can be good measures of both the frequency and duration of soil saturation.

Given the requirement that inundation/saturation must be present for a certain portion of the growing season it is important to understand how the concept of growing season should be applied. The definition of growing season is: "The portion of the year when soil temperatures at 19.7 inches below the soil surface are higher than biological zero (41 degrees F). For ease of determination this period can be approximated by the number of frost-free days." The Washington State Wetland Identification and Delineation Manual contains additional guidance on how to determine the growing season.

(10) Indicators of wetland hydrology. Indicators of wetland hydrology may include, but are not necessarily limited to: Drainage patterns, drift lines, sediment deposition, watermarks, stream gage data and flood predictions, historic records, visual observation of saturated soils, and visual observation of inundation. Any of these indicators may be evidence of wetland hydrologic characteristics.

Methods for determining hydrologic indicators can be categorized according to the type of indicator. Recorded data include stream gage data, lake gage data, tidal gage data, flood predictions, and historical records. Use of these data is commonly limited to areas adjacent to streams or other similar areas. Recorded data usually provide both short-term and long-term information about frequency and duration of inundation, but contain little or no information about soil saturation, which must be gained from soil surveys or other similar sources. The remaining indicators require field observations. Field indicators are evidence of present or past hydrologic events (e.g., location and height of flooding). Indicators are listed in order of decreasing reliability. Although all are valid indicators, some are stronger indicators than others. When a decision is based on an indicator appearing in the lower portion of the list, re-evaluate the parameter to ensure that the proper decision was reached. Indicators for recorded data and field observations include:

(a) Recorded data. Stream gage data, lake gage data, tidal gage data, flood predictions, and historical data may be available from the following sources:

(i) Corps of Engineers (CE) district offices. Most CE Districts maintain stream, lake, and tidal gage records for major water bodies in their area. In addition, CE planning and design documents often contain valuable hydrologic information. For example, a General Design Memorandum (GDM) usually describes flooding frequencies and durations for a project area. Furthermore, the extent of flooding within a project area is sometimes indicated in the GDM according to elevation (height) of certain flood frequencies (1-, 2-, 5-, 10-year, etc.).

(ii) U.S. Geological Survey (USGS). Stream and tidal gage data are available from the USGS offices throughout the Nation, and the latter are also available from the National Oceanic and Atmospheric Administration. CE Districts often have such records.

(iii) State, county, and local agencies. These agencies often have responsibility for flood control/relief and flood insurance.

(iv) Natural Resource Conservation Service Small Watershed Projects. Planning documents from this agency are often helpful, and can be obtained from the NRCS district office in the county.

(v) Planning documents of developers.

(b) Field data. The following field hydrologic indicators can be assessed quickly, and although some of them are not necessarily indicative of hydrologic events that occur only during the growing season, they do provide evidence that inundation and/or soil saturation has occurred:

CAUTION: Many delineators have made the mistake of assuming that the wettest conditions occur in the earliest part of the growing season - usually March and April. However, in some situations, the wettest time of the growing season may be later. This is especially true in areas that receive snowmelt run-off or irrigation water or are subject to tidal influence.

(i) Visual observation of inundation. The most obvious and revealing hydrologic indicator may be simply observing the areal extent of inundation. However, because seasonal conditions and recent weather conditions can contribute to surface water being present on a nonwetland site, both should be considered when applying this indicator.

(ii) Visual observation of soil saturation. Examination of this indicator requires digging a soil pit to a depth of 16 inches and observing the level at which water stands in the hole after sufficient time has been allowed for water to drain into the hole. The required time will vary depending on soil texture. In some cases, the upper level at which water is flowing into the pit can be observed by examining the wall of the hole. This level usually represents the depth to the water table. The depth to saturated soils will always be nearer the surface due to the capillary fringe. For soil saturation to impact vegetation, it must occur within a major portion of the root zone (usually within 12 inches of the surface) of the prevalent vegetation. The major portion of the root zone is that portion of the soil profile in which more than one half of the plant roots occur. CAUTION: In some heavy clay soils, water may not rapidly accumulate in the hole even when the soil is saturated. If water is observed at the bottom of the hole but has not filled to the 12-inch depth, examine the sides of the hole and determine the shallowest depth at which water is entering the hole. When applying this indicator, the season of the year and preceding weather conditions as well the duration of saturation must be considered. NOTE: This indicator has caused confusion in relation to the hydrology criteria, which stipulates that saturation must be to the surface. If the water table (the level at which standing water is found in an unlined hole) is found within twelve inches of the soil surface in a nonsandy soil, one can assume that soil saturation occurs to the surface. For sandy soils, the water table must be within six inches of the soil surface. However, simply finding the water table at the appropriate depth on one particular day, does not necessarily confirm that saturation to the surface for the appropriate length of time does occur. Conversely, finding the water table below the appropriate depth on one particular day, does not confirm that saturation to the surface for the appropriate length of time does not occur.

(iii) Watermarks. Watermarks are most common on woody vegetation. They occur as stains on bark or other fixed objects (e.g., bridge pillars, buildings, tree trunks, fences, etc.). When several watermarks are present, the highest reflects the maximum extent of recent inundation.

(iv) Drift lines. This indicator is most likely to be found adjacent to streams or other sources of water flow in wetlands, but also often occurs in tidal marshes. Evidence consists of deposition of debris in a line on the surface or debris entangled in above ground vegetation or other fixed objects. Debris usually consists of remnants of vegetation (branches, stems, and leaves), sediment, litter, and other waterborne materials deposited parallel: To the direction of water flow. Drift lines 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 than that indicated by a drift line.

(v) Sediment deposits. Plants and other vertical objects often have thin layers, coatings, or depositions of mineral or organic matter on them after inundation. This evidence may remain for a considerable period before it is removed by precipitation or subsequent inundation. Sediment deposition on vegetation and other objects provides an indication of the minimum inundation level. When sediments are primarily organic (e.g., fine organic material, algae), the detritus may become encrusted on or slightly above the soil surface after dewatering occurs.

(vi) Drainage patterns within wetlands. This indicator, which occurs primarily in wetlands adjacent to streams or in depressions with closed or restricted outlets and impervious subsoils, consists of surface evidence of drainage flow into or through an area that is restricted for a substantial duration. In some wetlands, this evidence may exist as a drainage pattern eroded into the soil, vegetative matter (debris) piled against thick vegetation or woody stems oriented perpendicular to the direction of water flow, or the absence of expected leaf litter. Scouring is often evident around roots of persistent vegetation. Debris may be deposited in or along the drainage pattern. CAUTION: Drainage patterns also occur in upland areas after periods of considerable precipitation; therefore, topographic position must also be considered when applying this indicator.

(vii) Oxidized rhizospheres surrounding living roots are acceptable hydrology indicators on a case-by-case basis and may be useful in ground water driven systems. Rhizospheres should also be reasonably abundant and within the upper 12 inches of the soil profile. Oxidized rhizospheres should be supported by other indicators of hydrology if hydrology evidence is weak. Caution: Make sure that the oxidation is occurring along live roots/rhizomes and thus, that they are not relict.

(viii) Local soil survey data - If you can field verify that the soil at your sampling site is a soil listed in the county soil survey or on the Washington State List of Hydric Soils, then the data in the soil survey referring to the flooding and/or high water table conditions for that soil can be accepted as valid for your site (assuming the site has not been effectively drained since the time it was mapped by the NRCS).

(ix) Water-stained leaves - Forested wetlands that are inundated at some time of the year will frequently have water stained leaves on the forest floor. These leaves are generally grayish or blackish in appearance, as a result of being underwater for significant periods. This indicator should be used with caution as water-stained leaves don't always indicate long-term inundation/saturation. It is important to compare the color of the leaves in the area presumed to be wetland with leaves of the same species in an adjacent area that is clearly upland. There should be a distinct difference in the color and texture of the leaves.

(x) FAC neutral test - In areas where hydrology evidence is weak or lacking, the FAC neutral test may be employed to corroborate the presence of sufficient hydrology. Apply as follows: Compare the number of dominants that are FACW and OBL with the number of dominants that are FACU and UPL (ignore the "neutral" FAC dominants). If there are more dominants that are FACW or wetter than there are dominants that are FACU or drier, then one can infer that the plant community is reflecting the presence of wetland hydrology. If there is a tie, compare the number of FAC and FAC- to see if there is a difference. If there is still a tie between the numbers of dominants, examine the nondominant species to determine if they provide an indication of how strongly hydrophytic the vegetation is. Any use of nondominants should be clearly documented and explained.

(xi) Other - Explain and provide rationale for use.

(11) Atypical situations. When a determination is made that positive indicators of hydrophytic vegetation, hydric soils, and/or wetland hydrology could not be found due to effects of recent human activities or natural events, it is necessary to employ different methods of determining the presence of indicators for hydrology, soils or vegetation. The term recent refers to the period of time since legal jurisdiction of an applicable law or regulation took effect.

When any of the three types of situations described below occurs, application of normal methods will lead to the conclusion that the area is not a wetland because positive wetland indicators for at least one of the three parameters will be absent. Therefore, apply procedures described in Part IV, Section F of the 1987 Corps of Engineers Wetland Delineation Manual or the Washington State Wetland Identification and Delineation Manual (as appropriate) to determine whether positive indicators of hydrophytic vegetation, hydric soils, and/or wetland hydrology existed prior to alteration of the area.

This section is applicable to delineations made in the following types of situations:

(a) Unauthorized activities. Unauthorized discharges requiring enforcement actions may result in removal or covering of indicators of one or more wetland parameters. Examples include, but are not limited to:

(i) Alteration or removal of vegetation;

(ii) Placement of dredged or fill material over hydric soils; and/or

(iii) Construction of levees, drainage systems, or dams that significantly alter the area hydrology. NOTE: This section should not be used for activities that have been previously authorized or those that are exempted from regulation.

(b) Natural events. Naturally occurring events may result in either creation or alteration of wetlands. For example, recent beaver dams may impound water, thereby resulting in a shift of hydrology and vegetation to wetlands. However, hydric soil indicators may not have developed due to insufficient time having passed to allow their development. Fire, avalanches, volcanic activity, and changing river courses are other examples. NOTE: It is necessary to determine whether alterations to an area have resulted in changes that are now the "normal circumstances." The relative permanence of the change and whether the area is now functioning as a wetland must be considered.

(c) Human-induced wetlands. These are wetlands that have been purposely or incidentally created by human activities, but in which wetland indicators of one or more parameters are absent. For example, road construction may have resulted in impoundment of water in an area that previously was nonwetland, thereby affecting hydrophytic vegetation and wetland hydrology in the area. However, the area may lack hydric soil indicators. NOTE: This is not intended to bring into jurisdiction those human-made wetlands that are exempted under agency regulations or policy. It is also important to consider whether the man-induced changes are now the "normal circumstances" for the area. Both the relative permanence of the change and the functioning of the area as a wetland are implied.

(12) Problem areas. There are certain wetland types and/or conditions that may make application of indicators of one or more parameters difficult, at least at certain times of the year. These are not considered to be atypical situations. Instead, they are wetland types in which wetland indicators of one or more parameters may be periodically lacking due to normal environmental conditions or seasonal or annual variations in environmental conditions that result from causes other than human activities or catastrophic natural events. When one of these wetland types is encountered, the methods described in Part IV, Section G of the 1987 Manual or the state manual should be used.

(13) Types of problem areas. Representative examples of potential problem areas, types of variations that occur, and their effects on wetland indicators are presented in the following subparagraphs. Similar situations may sometimes occur in other wetland types. Note: This section is not intended to bring nonwetland areas having wetland indicators of two, but not all three, parameters into jurisdiction. This list is not intended to be limiting.

(a) Wetlands on slopes (seeps) and other glacial features. Slope wetlands can occur in certain glaciated areas in which thin soils cover relatively impermeable unsorted glacial material or till or in which layers of sorted glacial material have different hydraulic conditions that produce a broad zone of ground water seepage. Such areas are seldom, if ever, flooded, but downslope ground water movement keeps the soils saturated for a sufficient portion of the growing season to produce anaerobic and reducing soil conditions. This fosters development of hydric soil characteristics and selects for hydrophytic vegetation. Indicators of wetland hydrology may be lacking during the drier portion of the growing season.

(b) Seasonal wetlands. In Washington, some depression areas have wetland indicators of all three parameters during the wetter portion of the growing season, but normally lack wetland indicators of hydrology and/or vegetation during the drier portion of the growing season. For example, obligate and facultative wetland plant species normally are dominant during the wetter portion of the growing season, while upland species (annuals) may be dominant during the drier portion of the growing season. Also, these areas may be inundated during the wetter portion of the growing season, but wetland hydrology indicators may be totally lacking during the drier portion of the growing season. It is important to establish that an area truly is a water body. Water in a depression normally must be sufficiently persistent to exhibit an ordinary high-water mark or the presence of wetland characteristics before it can be considered as wetland potentially subject to jurisdiction. The determination that an area exhibits wetland characteristics for a sufficient portion of the growing season to qualify as a wetland must be made on a case-by-case basis. Such determinations should consider the respective length of time that the area exhibits upland and wetland characteristics, and the manner in which the area fits into the overall ecological system as a wetland. Evidence concerning the persistence of an area's wetness can be obtained from its history, vegetation, soil, drainage characteristics, uses to which it has been subjected, and weather or hydrologic records. This situation is common in eastern Washington and parts of western Washington where precipitation is highly seasonal and/or prolonged droughts occur frequently. It is important to become familiar with the types of wetlands found in these areas. In some cases, it may be necessary to withhold making a final wetland determination until a site is examined during the wettest part of the growing season. Consultation with other experienced delineators may be helpful as well.

(c) Vernal wetlands - Although these systems are usually associated with California, Washington does have vernal wetlands, particularly in the region around Spokane. These wetlands are a distinct type of seasonal wetland described above. The hydrology in these wetlands is driven by winter and early spring rain and snowmelt and may be totally lacking by early summer. A wetland plant community grows and reproduces in spring in response to the wet conditions and is replaced by an upland plant community by summer. Attempts to delineate these wetlands in summer or fall may result in a false negative conclusion. In addition, during periods of extended drought, these wetlands may remain dry for several years.

(d) Vegetated flats. In both coastal and interior areas of Washington, vegetated flats are often dominated by annual species that are categorized as OBL. Application of normal sampling procedures during the growing season will clearly result in a positive wetland determination. However, these areas will appear to be unvegetated mudflats when examined during the nongrowing season, and the area would not qualify at that time as a wetland due to an apparent lack of vegetation.

(e) Mollisols (prairie and steppe soils) - Mollisols are dark colored, base-rich soils. They are common in grassland areas of the state, especially in eastern Washington and the prairies of the south Puget Sound basin. These soils typically have deep, dark topsoil layers (mollic epipedons) and low chroma matrix colors to considerable depths. 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. Become familiar with the characteristics of mollisols with aquic moisture regimes, and be able to recognize these from nonhydric mollisols.

(f) Entisols (floodplain and sandy soils) - Entisols are usually young or recently formed soils that have little or no evidence of pedogenically developed horizons. These soils are typical of floodplains throughout Washington, 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 wetland soils. Some entisols are easily recognized as hydric soils such as the sulfaquents of tidal salt marshes, 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 within 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 NTCHS criteria # 3 or # 4 are met are sufficient to verify these soils as hydric.

(g) Red parent material and volcanic ash soils - Hydric mineral soil 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. Additionally, some hydric soils in Washington that are influenced by volcanic ash or other volcanic material may not exhibit hydric soil indicators.

(h) Spodosols (evergreen forest soils) - These soils are usually associated with coniferous forests. Spodosols have a gray eluvial E-horizon overlying a diagnostic spodic horizon of accumulated (sometimes weakly cemented) organic matter and aluminum. 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 then coating the sand grains with organic matter and iron oxides in the second layer. Certain vegetation produces organic acids that speed podzolization including western hemlock (Tsuga heterophylla), spruces (Picea spp.), pine (Pinus spp.), larches (Larix spp.), and oaks (Quercus spp.) (Buol, et al, 1980). To the untrained observer, the gray leached layer may be mistaken as a field indicator of hydric soil, but if one looks below the spodic horizon the brighter matrix colors often distinguish nonhydric spodosols from hydric ones. The wet spodosols (formerly called "ground water podzolic soils") usually have thick dark surface horizons, dull gray E-horizons, and low chroma subsoils.

(i) Interdunal swale wetlands - Along the Washington 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 part of the season. In some cases, swales may be flooded irregularly by the tides. These wetlands have sandy soils that generally lack field indicators of hydric soil. In addition, indicators of wetland hydrology may be absent during the drier part of the growing season. Consequently, these wetlands may be difficult to identify.

(j) Vegetated river bars and adjacent flats - Along streams, particularly in arid and semiarid parts of the state, 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 for =12.5% of the growing season, they are wetlands. The soils often do not reflect the characteristic field indicators of hydric soils, however, and thereby pose delineation problems.



[Statutory Authority: RCW 90.58.140(3) and [90.58].200. 97-04-076 (Order 96-12), § 173-22-080, filed 2/5/97, effective 3/8/97.]