1. In response to questions from the field, the Qs & As on the 1987 Corps of Engineers Wetland Delineation Manual (1987 Manual) have been further clarified (in particular, questions #7 and #8). We clarified that for saturated-only systems, the saturation must be to the surface for the appropriate number of days during the growing season. Furthermore, we clarified that the number of days for inundation or saturation to the surface are consecutive, not cumulative. The enclosed Qs and As dated 7 October, 1991 supersede those previously distributed under the cover memorandum of 16 September, 1991.
2. I want to again emphasize that the 1987 Manual stresses the need to verify that all three parameters exist prior to identifying and delineating an area as a wetland. Further, the 1987 Manual focuses on hydrology (i.e., inundation and/or saturation to the surface). In situations where hydrology is questionable, the 1987 Manual requires stronger evidence regarding the hydrophytic nature of the vegetation. The 1987 Manual also stresses the need to use sound professional judgment, providing latitude to demonstrate whether an area is a wetland or not based on a holistic and careful consideration of evidence for all three parameters. As indicated in the 1987 Manual and the attached Qs and As, careful professional judgment must be used in situations where indicators of hydrology are not clear and the dominant vegetation is facultative.
JOHN F. STUDT
Chief, Regulatory Branch
Operations, Construction and
Readiness Division
Directorate of Civil Works
October 7, 1991
1.Q. What is the definition and practical interpretation of the growing season which should be used in the application of the 1987 Manual?
A. The 1987 Manual defines the growing season as "the portion of the year when soil temperatures at 19.7 inches below the soil surface are higher than biological zero (5 degrees C)". This is the definition found in Soil Taxonomy, and growing season months can be assumed based on temperature regimes (e.g., mesic: March- October). The 1987 Manual further states this period can be approximated by the number of frost-free days. The Waterways Experiment Station (WES) indicates that the county soil surveys, which utilize 32 degrees, provide the growing season for each county. There is some flexibility in the determination of the growing season in the 1987 Manual. The growing season, based on air temperature in the county soil surveys can be approximated as the period of time between the average date of the first killing frost to average date of the last killing frost, which sometimes does not accurately reflect the period of time when the soil temperatures are higher than biological zero. The source of the information may vary, however, the growing season generally is to be determined by the number of killing frost-free days. In certain parts of the country where plant communities in general have become more adapted to regional conditions, local means of determining growing season may be more appropriate and can be used.
2.Q. Should the determination of hydric soils be based on the presence of an indicator listed in the 1987 Manual higher on the list than the soils list or on the fact that a soil appears on the Hydric Soils of the United States. an indicator which is listed as less reliable in the hierarchy of hydric soil indicators in the 1987 Manual?
A. The order of soil indicators reliability as listed in the 1987 Manual remains valid and will be used. The reliability of the indicators is based on the fact that field verification of a soil's hydric characteristics is more accurate than mapping or soils lists. Soils listed on the most recent Hydric Soils list have been determined by the National Technical Committee for Hydric Soils to meet the criteria for hydric soils. When in the field, verification that mapped hydric soils actually exhibit indicators identified in me 1987 Manual for hydric soils is recommended. Although a soil may appear on the list of hydric soils, inclusions or disturbances may alter this designation to some degree, so the list alone may not always be reliable. In obvious wetlands, if the soil is on the list and the area meets the hydrology and vegetation criteria, the area is a wetland. As found with me 1989 Manual, one cannot rely solely on the fact that a soil is mapped as hydric in making the wetland delineation. all cases, best professional judgment should be used. The county lists provide valuable information, but again should not solely be relied on to make a final determination as to whether hydric soils are present. Verification of the presence of at least one of the indicators for hydric soils on the list (pages. 30-34) is required in conjunction with the use of a county soils list. The national soils list to be used has recently been updated by the NTCHS (June 1991), and this list will be used by the Corps in conjunction with the 1987 Manual.
3.Q. How should the 1987 Manual be applied with respect to the definition of "normal circumstances"?
A. The definition of "under normal circumstances" in the 1987 Manual states briefly that "this term refers to situations in which the vegetation has not been substantially altered by man's activities". As stated in item #3 of the memorandum of 27 August, 1991, the definition of normal circumstances used in the 1987 Manual has been clarified by Regulatory Guidance Letter (RGL) 90-7. Although this RGL deals primarily with agricultural activities in wetlands, paragraphs #3 & #4 discuss normal circumstances with respect to all areas potentially subject to 404. Further guidance on normal circumstances is found in RGL 86-9 regarding construction sites and irrigated wetlands. The guidance should be followed in preferential sequence of; 1) RGL 90-7, 2) RGL 86-9, and 3) 1987 Manual.
4.Q. Does the vegetation criteria in the 1987 manual require the use of the facultative(FAC) - neutral vegetation test (i.e., count the dominant species wetter and drier than FAC, and ignore all of the FACs in the vegetation determination)?
A. While the 1987 Manual mentions use of the FAC - neutral test for determining the presence of wetland vegetation in several places, the first indicator of wetland vegetation criteria is the presence of more than 50% of the dominant plant species FAC or wetter (not including FAC- species, which are considered non-wetland indicators under the 1987 manual). The indicator status of each of the dominant species is determined by consulting the current regional plant list published by the FWS. The 1987 Manual provides an option in this determination of applying the FAC - neutral test in cases where the delineator questions the status designation of a particular plant species on a subregional basis (see page 233. As always, any deviation from established protocol requires documentation. The FAC - neutral option may also prove useful in questionable areas or when the determination relies on the vegetation call in an area that is not otherwise an obvious wetland. Specifically, the 1987 Manual is replete with cautions and guidance that the Corps regulators must be confident that the area is wetland when the area has a FAC-dominated plant community. Uncertainty regarding the status of an area as a wetland where the dominant vegetation is FAC would be a valid reason to use the FAC - neutral option. Situations exist where use of the FAC - neutral method will not serve to provide any additional information as to the hydrophytic nature of the plant community (e.g., all species are FAC or there is an equal number of species wetter and drier than FAC such that they cancel each other out). In these cases, it is appropriate to consider the + and - modifiers associated with some FAC species, which indicate the species frequency of occurrence in a wetter or drier environment, in the overall assessment of the vegetation parameter. Documentation supporting reasons for using the FAC - neutral option must always be provided and acceptance of delineations, as always, remains up to the discretion of the District.
5.Q. Can indicators for any of the criteria in the 1989 Manual be used as indicators for verification of the same or other criteria presented in the 1987 Manual?
A. The indicators of hydrology in the 1987 Manual differ from those of the 1989 Manual, and are not interchangeable. In particular, the hydrology determination in the 1989 Manual often relied on evidence of properties from the soil and/or vegetation parameters. Indicators provided in the 1989 Manual for field verification of a certain criterion that are not presented in the 1987 Manual for application with the same criterion cannot be used except as additional information in support of the verification. It is unlikely that an area which is a wetland will fail to meet a criteria utilizing the indicators which are listed in the 1987 Manual.
6.Q. Will the other Federal agencies be utilizing the 1987 Manual in their wetland determinations as well as the Corps of Engineers?
A. EPA has concurred with the Corps using the 1987 Manual for all actions. Further, we understand that EPA will likely use the 1987 Manual for EPA's delineations as well. The other agencies (SCS & FWS) typically do not make delineations for purposes of Section 404.
7.Q. To what depth should one look in the soil to find indicators of hydrology?
A. In accordance with the 1987 Manual's guidance on reading soil color (D2), after digging a 16" soil pit observations should be made immediately below the A-horizon or within 10" of the soil surface (whichever is shallower). This guidance pertains to observations of indicators of the soil criterion. For indicators of saturation to the surface in the hydrology criterion, observations are made within a major portion of the root zone (usually within 12"), again in the 16" pit. Visual observation of standing water within 12" of the surface may, under certain circumstances, be considered a positive indicator of wetland hydrology (i.e., saturation to the surface) as stated on page 38. When using water table within 12" of the surface as an indicator of hydrology, care must be used to consider conditions and the soil types (i.e., to ensure that the capillary ability of the soil texture is considered in regard to the water table depth). Vegetation and soil properties used in the determination of hydrology in the 1989 Manual, are typically not available for field verification of this criterion in the 1987 Manual. However, the 1987 Manual allows for some flexibility with regards to indicators of wetland hydrology, and states that indicators are not limited to those listed on pages 37-41. Other indicators, such as some type of recorded data (e.g., soil surveys which provide specific and strong information about the soil series' hydrology) may be used to verify a wetland hydrology call in a saturated but not inundated area. Appropriate documentation to support the call is necessary in all cases.
8.Q. What length of time must wetland hydrology be present for an area to be determined a wetland under the 1987 Manual?
A. In the hydrology section of Part III, the 1987 Manual discusses the hydrologic zones which were developed through research at WES to indicate the duration of inundation and/or soil saturation during the growing season. Wetland hydrology is defined in the 1987 Manual as the sum total of wetness characteristics in areas that are inundated or have saturated soils for a sufficient duration to support hydrophytic vegetation. The 1987 Manual discusses hydrology in terms of a percent of the growing season when an area is wet (page 36). Generally speaking, areas which are seasonally inundated and/or saturated to the surface for more than 12.5% of the growing season are wetlands. Areas saturated to the surface between 5% and 12.5% of the growing season are sometimes wetlands and sometimes uplands. Areas saturated to the surface for less than 5% of the growing season are non-wetlands. The percent of growing season translates to a number of days, depending on the length of the growing season in any particular area (e.g., 12.5% of a 170-day growing season is 21 consecutive days). This system for classification of hydrologic zones based on stream gauge data transformed to mean sea level elevations is useful as a guide to time frames of wetness sufficient to create wetlands. The length of time an area is wet for hydrology is based on consecutive days during the growing season. If an area is only saturated to the surface for a period of between 5% and 12.5% of the growing season and no clear indicators of wetland hydrology exist (i.e., recorded or field data; also see answer #7 above), then the vegetation test should be critically reviewed. Specifically, in such cases a vegetative community dominated by FAC species would generally indicate that the area is not a wetland (unless the FAC- neutral test was indicative of wetlands). The actual number of days an area is inundated and/or saturated to the surface for an area to be called a wetland varies; the identification of an indicator of recorded or field data is necessary to document that an area meets the wetland hydrology criterion of the 1987 Manual (i.e., the list of hydrology indicators on pages 37-41, which are to be used in the preferential order shown; also see question #7). The number of days specified in the June 1991 Hydric Soils of the United States (i.e., usually more than 2 weeks during the growing season) as the criteria for hydric soils pertains to hydric soils and not the hydrology criterion of the 1987 Manual, which varies with the growing season as previously discussed.
9.Q. Will delineations made now under the 1987 Corps Manual be subject to redelineation under the revised 1989 Manual after it is finalized?
A. Wetland determinations made after 17 August, 1991, are made following the guidance provided in the 1987 Corps Manual and memoranda of 23 and 27 August, 1991 and these questions and answers. These delineations are subject to and remain valid for the period of time described in RGL 90-6. As discussed in Issue #4 of the preamble to the proposed revisions to the 1989 Federal Manual for Identifying and Delineating Jurisdictional Wetlands issued 14 August in the Federal Register, wetland calls made after the issuance date of these revisions but prior to finalization of the revised manual may be subject to redelineation under the new manual at the request of the landowner. Final actions will generally not be reopened. Wetland calls made under the 1989 Manual are already subject to redelineation under the 1987 Manual in accordance with the guidance issued 23 August. Until such time as the proposed revisions to the 1989 Manual are finalized, it is unclear as to what effect, if any, the equity provision in the preamble to the proposed revisions will have on the 404 program. Therefore, written delineations made with the 1987 Manual will explicitly state they are final for a period of three years as specified in RGL 90-6, subject to any equity provisions that may be adopted as part of implementation of the final revisions to the 1989 Manual.
10.Q. How does the 1987 Manual compare to the 1989 Manual or its proposed revisions?
A. The various manuals have been compared by WES and the side-by-side comparison is available for your information.
11.Q. Will applicants be subject to delay with use of the 1987 Manual?
A. During the initial transition to use of the 1987 Manual for wetland delineations as of 17 August, some delays are unavoidable. The Corps field offices must adhere to the procedures provided in the 23 August memorandum, while striving to expedite the review process to the extent possible. No offices should indicate that they cannot operate due to lack of guidance during this transition period. HQUSACE recognizes that there will be delays associated with implementing the Corps 1987 Manual and we will take these delays into account when reviewing district application performance data (e.g., % of IPs evaluated in 60 days). Districts should not stop the permit clock, but should indicate where substantial impacts to permit evaluation performance have resulted from implementation of the 1987 Manual.
1.Q. Which procedure should be followed for the field testing since the guidance provided initially states both the routine and comprehensive?
A. Since the criteria for determining the presence of hydrophytic vegetation is proposed to be the prevalence index, the comprehensive method must be used as neither the routine nor intermediate on-site methods will yield a prevalence index. The point intercept sampling procedure on pages 40471-40473 yields a PI directly and is stated that it is the procedure to be used in the determination of the PI on page 40455 of the Federal Register. Routine or intermediate on-site determinations methods can be used for determination of the limits of hydric soils (Step 1, page 40471) and wetland hydrology (Step 16, page 40473) necessary to be considered in conjunction with the vegetation assessment as described on pages. 40472-40473 (Steps 6-15). Documentation of deviations from the prescribed methodology should be noted in the field testing reports.
2.Q. Must all plants or just the dominants be looked at to determine the prevalence index (data sheets say dominants while procedure looks at individuals)?
A. All plant species, not just dominant plants, are considered in the prevalence index determination of hydrophytic vegetation. However, the point intercept sampling procedure in the comprehensive methods which is used to yield a PI requires the identification of only those species which are intercepted by an imaginary line extended from the points every 2 feet along the transect.
3.Q. How is one to compare site determinations made using the 1989 Manual and the proposed revisions when different methods (e.g., routine vs. comprehensive) were used?
A. Comparing the data from delineations previously performed under the 1989 Manual (regardless of the method employed at the time) with the data recorded during the field testing of the proposed revisions of the 1989 Manual, should be done to the level of detail possible. The resultant delineations from these different manuals and/or procedures are what these tests are comparing; some discussion of any differences and why they exist (e.g., changes in the criteria, indicators, and methodologies utilized) should be provided based on the teams or individual's observations, experience and best professional judgment.
4.Q. Are the regional indicators listed in the proposed revisions to the 1989 Manual the same for soils and hydrology?
A. Yes, they are proposed for use as an indicator of the soil criterion as well as corroborative information for use with the secondary indicators of hydrology.
5.Q. Do you always need to prove 21 days saturation?
A. Yes, but identification of one or more of the primary indicators of hydrology is proof that the area meets the 21 day hydrology criterion.
6.Q. Is there a map that goes with the regional indicators?
A. Yes, the regional indicators of soil saturation continue to be developed and are being proposed for use with the manual for the four Department of Agriculture, Soil Conservation Service main regions; Northeast, South, Midwest and West (see enclosed map).
7.Q. Can the soils list be used as corroborative information with a secondary indicator for verification that the hydrology criterion is met?
A. No, only the information listed can be used. Comments on the appropriateness of the information and suggestions for others should be provided during the comment period.
8.Q. Can blackened leaves be used as hydrology indicator?
A. No, only those listed in the list of hydrology indicators.
9.Q. Must three transects always be evaluated for the methodology described to determine the prevalence index?
A. No, in most cases, only 1 transect is required for purposes of these tests. The following guidance provides the exact circumstances under which options concerning the number of transects are permitted before proceeding to Step 11 and repeating the two transects: - If the prevalence index value determined for the first transect is less than 2.5 or more than 3.5, and, in the professional judgment of the investigators repeated transects are likely to provide the same result, the investigators need not repeat the transect. In cases where this shortened method is used, this should be reflected in the results. While the agencies recognize that this change in protocol does not strictly adhere to the method contained in the revised manual, it is nevertheless a practical step to reduce the demands of using the comprehensive method.
10.Q. How are the frost-free dates determined under the proposed revisions which the field testing should utilize?
A. The frost-free dates are to be determined by using the summary of growing season data developed by NOAA referred to on the first page of the Interagency Protocol. This information is available for each state and will be provided to the Divisions for distribution to the field in the near future.
11.Q. Must sites visited and data collected prior to the recently released revised data sheets be redone using the new forms?
A. No, both versions collect essentially the same data. Sections I (Background) and VI (Wetland Evaluation) of the revised data sheets are identified as sections that will generally apply to the entire site, and in most cases will not have to be repeated for each individual transect. Besides the reorganization of these forms, revisions have been made to collect data on the 1987 Manual, include questions on the regional indicators, and clarify the functions and values assessments.
12.Q. How should the Corps provide comments on the proposed revisions to the 1989 manual?
A. Each District is to submit comments to their Division office for consolidation into one response to EPA (in accordance with the Federal Register issued 14 August) prior to the end of the comment period (currently 15 October); a copy of these comments are to be provided to CECW-OR. Each Division is encouraged to provide comments to HQUSACE at least one week prior to the end of the comment period so that key issues and concerns raised may be stressed in the comments which will come from Headquarters. In addition, the Corps has the opportunity to comment through the interagency field testing reports, which are due to HQUSACE by 1 November. HQUSACE and WES will continue to participate in interagency efforts to finalize revisions to the 1989 Manual until such time as the revisions become final. There is consideration being given as to the need for a time extension to the comment period (and therefore the field testing). If this becomes final, we will let the Divisions know as soon as possible.
13.Q. Is the information gathered during the inter agency field testing available for release to the public and may the public accompany the teams in the field?
A. The interagency field testing of the proposed revisions to the 1989 Federal Manual for Identifying and Delineating Jurisdictional Wetlands published in the 14 August, 1991 Federal Register is being performed to evaluate the technical validity, practical utility, and clarity of understanding of the proposed revisions. The results of the field testing will be taken into consideration during the final revisions to the 1989 Manual. The information gathered during the field testing is considered to be predecisional by HQUSACE and inappropriate for release prior to the finalization of the proposed revisions. Counsel is preparing written guidance on this issue and it will be distributed to the Divisions as soon as possible.
14.Q. Will delineations made now under the 1987 Corps Manual be subject to redelineation under the revised 1989 Manual after it is finalized?
A. Wetland determinations made after 17 August, 1991, are made following the guidance provided in the 1987 Corps Manual and memoranda of 23 and 27 August, 1991. These delineations are subject to and remain valid for the period of time described in RGL 9-6. As discussed in Issue #4 of the preamble to the proposed revisions to the 1989 Federal Manual for Identifying and Delineating Jurisdictional Wetlands issued 14 August in the Federal Register, wetland calls made after the issuance date of these revisions but prior to finalization of the revised manual may be subject to redelineation under the new manual at the request of the landowner. Final actions will generally not be reopened. Wetland calls made under the 1989 Manual are already subject to redelineation under the 1987 Manual in accordance with the guidance issued 23 August 1991. Until such time as the proposed revisions to the 1989 Manual are finalized, it is unclear as to what effect, if any, the equity provision in the preamble to the proposed revisions will have on the 404 program. Therefore, written delineations made with the 1987 Manual will explicitly state they are final for a period of three years as specified in RGL 9~6, subject to any equity provisions that may be adopted as part of implementation of the final revisions to the 1989 Manual.