DEPARTMENT OF THE ARMY
U.S. Army Corps of Engineer*
WASHINGTON, D.C. 20314-1OOO
REPLY TO
ATTENTION OF;
CECH-OR • . '-6MAR1992
MEMORANDUM FOR SEE DISTRIBUTION °
SUBJECT: Clarification and Interpretation of the 1987 Manual
„ \
- 1. The purpose of this memorandum is to provide additional
clarification and guidance concerning the application of the
Corps of Engineers Wetlands Delineation Manual. Technical Report
Y-87-1, January 1987," Final Report (1987 Manual). As discussed
in my 20 February 1992 memorandum, procedures for the
identification and .delineation of wetlands must be fully
consistent with both the 1987 Manual and the Questions and
Answers issued 7 October 1991. The technical and procedural
guidance contained in paragraphs 2 thru 6 below has been prepared
by the Waterways Experiment Station (WES) and is provided as
further guidance. The following guidance is considered to be
.consistent with the 1987 Manual and the 7 October Questions and
Answers. Further, this guidance will be presented in the
upcoming Regulatory TV wetlands delineation training sessions in
FY 92. - The alternative technical methods of data gathering
discussed below are acceptable as long as the basic decision
rules (i.e., criteria and indicators) established in the 1987
Manual are applied. Also enclosed is a revised data form which
may be used in lieu "of the routine data sheet provided with the
1987 Manual, if desired. As discussed in my 20 February 1992
memorandum, to the field, regional approaches and/or/ alternative
data sheets must be reviewed and approved by HQUSACE (eECW~©R)
,prior to regional implementation. Notwithstanding this
requirement, we encourage interagency coordination arid
cooperation on implementation "of the 1987 Manual. Such
cooperation can facilitate the continued success of our use of
the 1987 Manual.
2. Vegetations .
a. Basic rule: More "than 50 percent of dominant species
from all strata are OBL, FACW, or FAC (excluding FAC-) on the
appropriate Fish and Wildlife Service regional list of plant
species that occur in wetlands.
b. The 1987 Manual provides that the 3 most dominant .
species be selected from each stratum (select 5 from each stratum
if only 1-2 strata are present) «. However, alternative
ecologically based methods for selecting dominant species from -
each stratum are also acceptable. The dominance method described
in the 1989 interagency manual is an appropriate: alternative
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CECW-OR
SUBJECT: Clarification and Interpretation of the 1987 Manual
method.. (1989 Manual, p. 9, para. 3.3)
•
c. The 4 vegetation,strata (tree, sapling/shrub, herb, and
woody vine) described in the 198.7 Manual are appropriate.
However, a 5-stratum approach .(tree, sapling, shrub, herb, and
woody vine) is an acceptable alternative.
d. The 1987 Manual states on page 79 that hydrophytic
vegetation is present if 2 or more dominant species exhibit
. morphological adaptations or have known physiological adaptations
for-wetlands. This rule should be used only after the basic rule
is applied; use caution with adaptations (e.g., shallow roots)
that can develop for reasons other than wetness,, Furthermore,
. the morphological adaptations must be observed on most • -
- individuals of the dominant species.
e. In areas where the available evidence of wetlands
hydrology or hydric soil is weak (e.g., no primary indicators of
hydrology)t the Facultative Neutral (FAC neutral) option
may be used to help clarify a wetland delineation. . Use of the
FAC neutral option is explained in paragraph 35(a), page 23,
of the 1987 Manual. Use of the FAC neutral option is at the
discretion'of the District. Further, the FAC neutral option
cannot be used to exclude areas that meet the "basic vegetation
rule" and the hydrology"and hydric soil requirements.
3. Hydrology:
a. Areas which are seasonally inundated and/or saturated to
the surface for a consecutive number of days for more than 12.5
percent of the growing season are wetlands, provided the soil and
vegetation parameters are met. Areas wet between 5 percent and
12.5 percent of the growing season in most years (see Table 5,
page 36 of the 1987 Manual) may or may not be wetlands. Areas
saturated to the surf ace for less than 5 percent of the growing
season are non-wetlands. Wetland hydrology exists if field
indicators are present as described herein and In the enclosed
data sheet.
b. To evaluate hydrologic data (e.g., from stream gages or
groundwater wells) growing season dates are required. Soil
temperature regime (i.e., period of the year when soil
temperature at 20 inches beJLow the surface is above 5 G) is
the primary definition of growing season, but data are rarely
available for individual sites. Broad regions based on soil
•temperature^regime (e.g., mesic, thermic) are not sufficiently
site-specific. For wetland determinations, growing season can be
estimated from climatological data given in most SCS county sail
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CEGW-OR .
SUBJECT: Clarification-and Interpretation of the 1987 Manual
surveys (usually in Table 2 or 3 "of modern soil surveys) .
Growing season starting and ending dates will generally be
• determined based on the *!28 degrees F or lower" temperature
threshold at a frequency of "5 years in 10." In the south, at
the discretion of the district, 'it may be more appropriate to use
the 32 degree F threshold. , -
c. In groundwater-driven systems, which lack surface
indicators of wetland hydrology, it is acceptable to use local
.Soil Conservation Service (SCS) soil survey information^to
evaluate the hydrology parameter (p. 37 in the Manual) in
conjunction with other information, such as the FAC neutral test.
Use caution in areas -that may have been recently drained.
•d. Oxidized rhizospheres surrounding living roots are
acceptable hydrology indicators on
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CECW-OR
SUBJECT: Clarification and Interpretation of the 1987 Manual
5. Methods;;
0 r
a. As stated 'in the 1987 Manual (footnote, p. 76),
alternative plot sizes arid dominance measures are acceptable.
b. For comprehensive determinations involving a patchy or
diverse herb layer, a single, centrally located 3.28 x 3.28-
foot quadrat may not give a representative sample. As an
alternative, the, multiple-quadrat procedure presented in the
.1989 Manual (p. 42) is recommended. ;
6. Problem Areas
a. Page 93, paragraph 78 of the 1987 Manual states that
similar problem situations may occur in other wetland types;
therefore, problem areas are not limited to this list.
. • =«•
b. Problem soil situations mentioned elsewhere in the
Manual include soils derived from red parent materials, some
Entisols, .Mollisols, and Spodosols. .
7. Questions concerning this information should be directed to
Ms. Karen A. Kochenbach, HQUSACE (CECW-OR) , at (202) 272-1784, or
Mr. James S. Wakeley,, WES, at (601) 634-3702.
End , ^vARTmm E. WILLIAMS
Major General, USA .
Directorate of Civil Worles
DISIERIBDTION:
(SEE PAGE 2 & 3)
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DATA FORM
ROUTINE WETLAND DETERMINATION
(1987 COE Wetlands Delineation Manual!
Project/Site: '
Aoolicant/Owner:
Investigator: >
Do Normal Circumstances exist on the she?
Is the site significantly disturbed (Atypical Situation}?
Is the area a potential Problem Area?
(If needed, explain on reverse.)
-
Yes
Yes
Yes
No
No
No
Date:
Countv:
State:
Community ID:
Transect ID:
Plot ID:
VEGETATION
Dominant PSant Soaetea • Stratum Indicator
1. ' ' '
2. " '
3.
4. •>'•••" '
5. '
fi. . • -
1. • ' •
&.
Percent of Dominant Species that are OBL. FACW or FAC
Remarks: * .
Dominant Want Soeetes Stratum Indicator
a.
10.
12.
13- ' .._••••
14.
is. - - . ..
16-
HYDROLOGY
Recorded Data (Describe in Remarks)?
_ Stream. Lake. , or Tide 6miQ«
• Aerial Photograph*
__ Other '
No Recorded Data Available
'Field Observations:
Depth of Surface Water:
Depth to Free Water in PsC
Wetland Hydrdoev indicator*:
Primary Indicators:
Inundated .
; Saturated in Upper 12 Inches
Wat«f Marks
, Drift Lines . -
' Sediment Deposits
' Drainage Patterns in Wetlands
Secondary Indicators (2 or more required):
f Oaddfced Root Channels in Upper 12 Inches
Watar-Stainsd Laavsa
Local So3 Survey Data
_
Other (Explain in Remarks)
R«nnmrk«:
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SOILS
Mop Unit Name
(Series «nd Pliaie):
Taxonomy (Subgrouol:
Drainago Class: _
fidd Observations
Confirm Maoped TYP«? Yes No
Profile Description;
Depth
finehM) Horizon
Matrix Color Mottle Colors MottU Taxturo. Concretions.
(Munsell Moist) (Munsell Moistl . * Abundance/Contrast Struerufg. etc.
Hydric So3 IrxCc*tor»:
„ „ Hi«to«ol
___>Ki»tic Eptpodon
^ulfidi'e Odor
___ Aqiao Mot«ura
- - Reducing Condition*
Glrved or Low-Chroma Color*
__ Concretion*
.High Organic Content in Surface Layer in Sandy Soils
. Organic Streaking in Sandy. Soils
. Listed on Local Hydric SoQs Ust
_ lasted on National Hydric Soils List
. Other (Explain in Remarks)
Remarks;
WETLAND DETERMINATION
Hydrophyric V*g»t«ion Present?
Wetiand Hydrology Prmsant?
Hydrie Soils Pr»«ent?
Ymm No (Orel*)
Yes No
Y»s No
Is tWs Sampfing Point Within s W«tiand? Y« Ne
Approvec oy HQUSACE a/32.
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DEPARTMENT OF THE ARMY
U.S. Army Corpi of Engineers
WASHINGTON. O.C. 20314-1000
REPLY TO •
ATTENTION OF: 7 October 1991
CECW-OR
e • - ' .
MEMORANDUM FOR SEE DISTRIBUTION
SUBJECT: Questions & Answers on 1987 Manual •
1, In response to questions froai the fieldr the Qs &'AS on the
1987 Corps of Engineers Wetland Delineation Manual (1987 Manual)
have been further clarified (in particular, questions #7 & 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 surf ace are consecutive,
not cumulative. The' enclosed Qs and As -dated 7 October, 1991
supercede those previously distributed under the coveo* memorandum
of 16 September, 1991.
2. .1 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 &\or
saturation to the surf aicej,' 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
judgement, 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 judgement
onust be used in situations where indicators of hydrology are not
clear and the dominant vegetation ,is facultative.
F, STUDT . --....' ...
Chief, Regulatory Branch
Operations, Construction and
Readiness Division
Directorate of Civil Works
Enclosure
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Questions s Answers
on 1987 Corps of Engineers Manual '
l.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)M. 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 or on the series
name appearing on the Hvdric Soils of the United States list, an
indicator which is listed as less reliable in the hierarchy of
bydric 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 far Hydric.Soils . .
(NTCHS) to meet the criteria for hydric soils. When in the field,
verification that mapped--hydric soils actually exhibit indicators
identified in the 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 the 1989 Manual,
one cannot rely solely on the fact that a soil is mapped as hydric
in making the wetland delineation. In all cases„ best professional
CECW-OR, .October 7, 1991 Page 1
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judgement 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 (pgs. 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 vill be used by the Corps in conjunction with the 1987 Manual.
3"Q: .H?w 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 aan«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 i987 manual require the
use of the facultative (FAC)-neutral vegetation test (i.e.,-count
the dominant species wetter & 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 23). 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 wita cautions
and guidance that the Corps regulators roust be confident that the
area is ^ wetland when the area has1 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
CECW-OR, October 7, 1991 - . Page 2
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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
may be appropriate to consider the + and - modifiers associated
with some FAC specie's, which indicate the species frequency of
occurrence in a wetter or drier environment, in the Coverall
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 delineatipns 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 iow 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 ma j or portion of the root zone "
(usually within 12") , again in the 16" pit. Visual observation of
standing water within 12M 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«,
CECW-OR, October 7, 1991 Page 3
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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 surf ace 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
the 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.ea, 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 -
CECW-OR, October 7, 1991 Page 4
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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 Sta-h^c'
(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 & 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 f inalization 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
HGL 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.
% , ' *
I 11.Q. Will applicants be subject to delay with use of 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
CECW-OR, October 7, 1991 Page 5
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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 the 1987 Manual» •
CECW-OR, October 7, 1991 - , . Page 6
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