APPROACH AND METHODS
Wetland Determination
Two levels of information were gathered for this analysis. These included:
a) Review of preliminary site data and,
b) On-site investigation to determine the presence of wetlands.
a)
A review of existing information was conducted to develop background knowledge of
physical features, and to identify the potential for wetland occurrence on the subject
property. The resource documents available for preliminary review of the site conditions
included: USDA Soil Conservation Service (SCS), "Soil Survey of Jefferson County
Area Washington", (1987) aerial photography, and Jefferson County Planning
Department data.
b)
During the on-site investigation, wetland areas were determined and verified on the basis
of three parameters: Hydrophytic Vegetation, Hydric Soils, and Wetland Hydrology, as
recommended in the Washington State Identification and Delineation Manual (Washington
State Department of Ecology, Ecology Publication #96-944, March 1997). See PTMC
19.05.110 B 2. Wetland classification for wetland are done using the Washington State Rating
System for Western Washington, August 1993 as required and defined in PTMC 19.05.110 B
3.
A positive wetland determination is made when all three parameters are present, or in certain
situations determined following the guidelines recommended in wetland determination procedures, or for
atypical situations or problem areas.
Hydrophytic Vegetation
Areas where more than 50% of the dominant species present from all strata are hydrophytes
(plants adapted to growth and reproduction in saturated soil conditions) are considered to be inside the
wetland boundary, unless clear evidence of hydric soils or wetland hydrology cannot be established. A
species is considered dominant if it is equal to or greater than 20% areal cover, or exerts a controlling
influence on, or defines the character of a community. Hydrophytic vegetation is determined to be
present, when under normal circumstances:
More than 50% of the dominant plant species in a plant community have an indicator
category of Obligate Wetland (OBL), Facultative Wetland (FACW), and/or Facultative (FAC) as listed in
"National List of Plant Species that Occur in Wetlands: Northwest (Region 9)", (Reed, Porter B., Jr.,
1988), and the "1993 Supplement to National List of Plant Species That Occur in Wetlands: Northwest
(Region 9)" dated December 1993 that became effective on March 31, 1994. Indicator categories of
FACW+, FACW-, FAC+, are included as FACW status.
'FAC+ species are considered to be wetter (i.e., have a greater estimated probability of occurring
in wetlands) than FAC species, while FAC- species are considered to be drier (i.e., have a lesser estimated
probability of occurring in wetlands) than FAC species.' Plant indicator status definitions are presented in
TABLE 1 below.
This Plant Indicator Status Categories system was developed for the USFWS National Wetlands
Inventory by Cowardin et al. (1979). The National Plant List Panel, Reed, Porter B., and Jr. modified it
Purpose and Approach Continued
in 1988 and 1993. The Wetland Indicator Category (WIC) used in this report refers to the plants Indicator
Symbol as referred to in the table below.
National Indicators reflect the range of estimated probabilities (expressed as a frequency of
occurrence) of a species occurring in a wetland versus a non-wetland across the entire distribution of the
species. ("National List of Plant Species that Occur in Wetlands: Northwest (Region 9)", Reed, Porter B.,
Jr., 1988), and the 1993 Supplement to List of Plant Species That Occur in Wetlands: Northwest (Region
9) dated December 1993 that became effective on March 31, 1994. Percentages expressed as estimated
probability.
TABLE 1
Indicator Category
Indicator Symbol
Definition
OBLIGATE WETLAND
PLANTS
OBL
Occur almost always, >99% (estimated
probability) in wetlands under natural
conditions. <1% in non wetlands.
FACULTATIVE WETLAND
PLANTS
FACW
Usually occur in wetlands, 67-99% and
1-33% in non-wetlands.
FACULTATIVE PLANTS
FAC
Equally likely to occur in wetlands and
non-wetlands 34-66%.
FACULTATIVE UPLAND
PLANTS
FACU
Usually occur in non wetlands 67-99%,
but occasionally found in wetlands 1-33%.
OBLIGATE UPLAND
Plants
UPL
Almost always occur in non-wetlands of
Northwest Region 9, >99%. <1%
in wetlands.
Hydric Soils
There have been tremendous scientific changes since 1991 in several of the indicators such as the
introduction of aquic conditions to cover the requirements for saturation, reduction, and morphological
indicators used to define the modified aquic moisture regime, and mottles and low chroma colors being
replaced by redoximorphic features. Because of these changes, we consult the US Department of
Agriculture, Natural Resource Conservation Service. 1998. "Field Indicators of Hydric Soils in the
United States, Version 4.0". G. W. Hurt, Whited, P. M., and Pringle, R. F. (eds.), USDA, NRCS, Ft.
Worth, TX for guidance and decision in making final hydric soils determinations.
Additionally, compliance to changes in Hydric Soils of the United States published in Federal
Register/Vol. 59, No. 133/July 13, 1994 and Vol. 60, No. 37/February 24, 1995 addressing Criterion 2 of
the Criteria for Hydric Soils definition is being observed. The main purpose for the criteria is to create
Hydric Soil Lists. Criteria 1, 3, and 4 can serve as both database criteria and as indicators for
Purpose and Approach Continued
identification of hydric soils. When Criteria 1,3, and 4 are used to document the presence of a hydric soil,
proof that anaerobiosis exists must also be obtained. Criterion 2 serves only to retrieve hydric soils from
the database. Also, the wording for Criteria 1 and 2 were changed in 1999 to incorporate recent changes
in Soil Taxonomy (Soil Survey Staff, 1999).
Field indicators of hydric soil conditions in this document, (Land Resource Region (LRR) A that
includes Western Washington), are presented here in an abbreviated form and include:
(1)
ALL SOILS:
A1. Histosols - (organic soils having 16 inches or more of the upper 32 inches as organic
peat or muck soil material); A2. Histic Epipedons - (normally a peat or muck surface horizon or
layer 8 inches or more thick); and A4. Hydrogen sulfide - (sulfidic odor in soil material within 12
inches of the soil surface).
(2)
SANDY SOILS:
S1 - a mucky modified mineral layer; S4 - a gleyed matrix; S5 - sandy redox concentrations;
and S6 - a matrix stripped of iron/manganese oxides and/or organic matter.
(3)
LOAMY AND CLAYEY SOILS:
F1 - a mucky modified mineral layer; F2 - a gleyed matrix; F3; - a depleted matrix without a
dark surface and F4 and F5 - a depleted matrix with dark or thick dark surfaces; F6 - a dark
surface and a redox 4 inch thick layer ≤12 inches deep with a matrix value ≤3 with a chroma ≤1 or
2 or less with ≥2% and ≥5% distinct or prominent redox concentrations respectively; F7 - a dark
surface layer with redox depletions 4 inch thick with value ≥5 and chroma ≤2 and ≤ 12 from the
surface of the soil that has a matrix value ≤3 and chroma ≤1 or ≤2 and ≥10% and ≥20% redox
depletions respectively; and F8 - redox concentration within 6 inches of a soil surface in
depressions subject to ponding.
Wetland Hydrology
Water is the driving force for wetlands. Indications of wetland hydrology are those where the
presence of water has an overriding influence on characteristics of vegetation and soils due to anaerobic
and reducing conditions, respectively.
Areas that are seasonally saturated and/or inundated to the surface for a consecutive number of
days for more than 12.5% of the growing season are wetlands provided the soil and vegetation parameters
are met. Areas wet between 5% and 12% of the growing season in most years may or may not be
wetlands. Areas saturated to the surface for less than 5% of the growing season are non-wetlands.
Wetland hydrology exists if field indicators are present.
Field indicators of wetland hydrology may include, but are not limited to visual observations of
inundation, ponding, soil saturation, oxidized root channels (rhizospheres) associated with living roots
and rhizomes, watermarks, drift lines, water-borne sediment deposition, or wetland drainage patterns.
The growing season starting and ending dates are required to evaluate hydrologic data. For
Purpose and Approach Continued
wetland determinations, the growing season is determined using the local SCS county soils surveys.
Generally, the growing season is calculated based on the "28 degrees F or lower" temperature threshold at
a frequency of "5 years in 10". For much of western Washington at low elevations, the mesic growing
season (March 1 to October 31) has been considered a good rule. However, in some areas of the Puget
Sound Lowlands and coastal areas the growing season occurs all year round because the soil temperature
at 19.7 inches below the soil surface is higher than 41 degrees F.
Plant Identification and Classification
Primary references used for scientific plant names and the endemic and non-native or exotic
status of plants to the North Olympic Peninsula were determined as found in Flora of the Pacific
Northwest by Hitchcock and Cronquist, Univ. of Washington Press, 1972. Other references referred to
included: (1) A Field Guide to the Common Wetland Plants of Western Washington & Northwestern
Oregon by Sarah Spear Cooke, editor, Washington Native Plant Society, May 1997; Wetland plants of
Oregon & Washington by Jennifer Guard, Lone Pine Publishing, 1995; (2) Plants of the Pacific
Northwest Coast- Washington, Oregon, British Columbia & Alaska edited by Pojar and Mackinnon, D.C.
Forest Service, Research Program, Lone Pine Publishing, 1994 and, D.C. Forest Service, Research
Program, Lone Pine Publishing, 1994; and (3) Northwest Weeds by Ronald J. Taylor, Mountain Press
Publishing Company, 1990