Selecting Sites for Comparison with
Created Wetlands
Northrop Services, Inc., Corvallis, OR
Prepared for
Corvallis Environmental Research Lab., OR
Nov 87
PB88-132204
I
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EPA/600/D-37/337
November 1987
SELECTING SITES FOR COMPARISON WITH CREATED WETLANDS
By
Brooke Abbruzzese, Anastasla B. Allen,
Sandra Henderson, and Mary E. Kentula
Northrop Services, Inc.
Corvallis, OR 97333
EPA Contract 68-03-3246
EPA Project Officer
E. Preston
ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CORVALLIS, OR 97333
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TECHNICAL REPORT DATA
(Unit md/*urnetioni on iht rtttru if,
I.MCOftT NO.
| EPA/600/D-87/337
4. TITLE AND JU«TITLS
: Selecting Sites for Compari
i
a.
son with Created Wetlands
1. AUTMOKI*)
Brooke Abbruzzese, Anastasia B. Allen, Sandra
Henderson, and Mary E. Kentula
9. S>8«f QSWIKG ORGANIZATION MAMi AMD AOOBOSS
Northrop Services, Inc.
Corvallis, OR
13. SPONSORING AGENCY NAMt AND ADO
Environmental Research Labc
Office of Researcn and Deve
U.S. Environmental Protectic
Corvallis, OR 97333
Mit*
ratory
'lopment
n Agency
!. MCCIPItNTY ACCKS£IO*»NO.
r£ ft- S3 I 1 6n
i. MCPONT OATS
November 1987
1. PINPOftMINO OMOANIZATIQN CODE
1. PIftPOftMIMO OMBAMIZATlOta MtPOMT MO.
10. PROGRAM KL(iMliWY MO.
11. COWY HACY/6HAMY MO.
68-03-3246
•
13. TVf C Of MIPOAT AND Ct^lOO COVtMtD
Symposium paper
14. fON«OMINC AOfNCV CODE
EPA 600/02
l». SyffLlMINTAKY HOTt*
I98/. Proceedings Symposium 87 Wetlands/Peatlands, Alberta, Canada, August 23-27.
IS. AtiTMACT
This paper describes the method used for selecting nati;. al wetlands to compare with
created wetlands. The rasults-of the selection proces' arid the advantages and dis-
advantages of the method are discussed.
The random site selection method required extensive field work and may have yielded
fewer sites with potential for long term comparison than a more subjective approach.
However, valuable information was derived on trends in wetland loss and public atti-
tudes toward government research. Most important, the method provided a statistically
defensible means of obtaining a set of sites. The data from the pilot study will
estimate the variability of natural wetlands within the ecoregion. Analysis of the
variability between ecoregions will be possible with similar studies in other areas of
the country. These studies will give EPA a framework for setting standards for wetland
creation and restoration. x
\
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1. DESCRIPTORS
KIV WONDS AMD DOCUM'VT ANALYSIS
b.lDINTIFItftS/OPIN INOfOTf AMS
18. DlSTAiftUTION STATf MINT
Release to Public
'•••fi^TaVsWe'd^1*'^
to. ticuftiYv CLASS muiMwr;
Unclassified
c. COSATl FieW/Cioup
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11. NO. Of fACE»
31. f MtCI
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OA tttm »IO-1 (§.73)
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NOTICE
This document has been reviewed in accordance with
U.S. Environmental Protection Agency policy and
approved for publication. Mention of trade names
or commercial products does not constitute endorse-
ment or recommendation for use.
ii
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SELECTING SITES FOR COMPARISON WITH CREATED WETLANDS
Abbruzzese, Brooke, Anastasia B. Allen, Sandra Henderson and Mary
E. Kentula. Northrop Services, Inc., 200 S.W. 35th Street,
Corvallis, Oregon 97333, USA.
ABSTRACT
A pilot study was conducted in the state of Oregon for the
US Environmental Protection Agency (EPA). The purpose of the
study was to evaluate the success of wetland creation and
restoration reouired as compensation for wetland losses permitted
under Section 404 of the Clean Water Act. This paper describes
the method used for selecting natural wetlands to compare with
created wetlands. The results of the selection process and the
advantages and disadvantages of tne method are discussed.
50 natural wetlands in the Portland urbar. area of the
Willamette Valley Ecoregion, representative ot the size, type and
land use of created wetlands were randomly selected from US Fish
and Wildlife Service National Wetland Inventory maps. Field
reconnaissance revealed that over 504 of the sites had already
been destroyed by agricultural conversions and urban-industrial
development. Landowners denied permission to sample 354 of the
remaining sites. Access for sampling was granted for 15 sites,
which constituted the final set of comparison sites.
The random site selection method required extensive field
work and nay have yielded fewer sites with potential for long
term comparison than a more subjective approach. However,
valuable information was derived on trends in wetland loss and
public attitudes toward government research. Most important, the
method provided a statistically defensible means of obtaining a
set of sites. The data from the pilot study will estimate the
variability of natural wetlands within the ecoregion. Analysis
of the variability between ecoregions will be possible with
similar studies In other areas of the country. These studies
will give EPA a framework for setting standards for wetland
creation and restoration.
INTRODUCTION
The Clean Water Act of 1972 was instituted to "restore and
maintain the chemical, physical, and biological Integrity of the
nation's waters" (Paulson 1985}. Section 404 of the Ac*.
regulates disposal of solid materials into water bodies.
1
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Abbruzzese et al 2
In 1977, the legislation was strengthened to give additional
protection to wetlands.
The US Environmental Protection Agency (EPA) and the Army
Corps of Engineers (COE) jointly administer the Section 404
program which issues permits for dumping fill into wetlands and
other sensitive aquatic areas. COE is the permitting authority.
EPA has power of oversight which includes responsibility for
establishing environmental criteria for permit review.
Permit applications may be denied if impacts to water
quality and supply, wildlife, a.nd recreation are considered
unacceptable. If wetland losses are permitted under Section 404,
the creation or restoration of wetlands is often required as
mitigation for the losi.es. The use of wetland creation and
restoration as a form of compensation has increased over the
years and with it, the number of projects.
EPA 1s concerned about the effectiveness of mitigation. The
question central to the Agency's research on mitigation 1s "How
well do created and restored wetlands replace the ecological
functions of the wetlands that were destroyed?" A pilot study
was conducted in the summer of 1987 to test methods for
evaluating and monitoring created and restored wetlands. A set
of sites was needed to compare vegetation, soils, water, and
topographic characteristic: of natural and created wetlands. The
selection of these comparison sites 1s discussed in this paper.
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Abbruzzese et al 3
No sy s teraati c , large scale evaluation of mitigation
projects has been undertaken; most studies of mitigation are case
studies with no sites for comparison. Quammen (1986) reviewed
studies of wetland mitigation and found that most rated the
success of projects on the basis of compliance with permit
requirements, or whether or not the projects had been
implemented.
However, a study of created salt marshes in New Jersey
(Shisler and Charette 1984) used paired reference sites. Each
mitigation project was paired with a naturally occurring wetland.
Characteristics of the vegetation, sediment and macro-inverte-
brates of each pair were compared. The criteria used to select
each reference site were proximity to the created site and
similarity of age and vegetation type. The research of the COE
Dredged Materials Program (Newling and Landin 1985) also used
paired sites. Similarity in habitat, hydrology, ownership and
level of disturbance were considered 1n the selection of
reference sites for a long term study of habitat development at
dredged material disposal sites. Since these studies relied on a
limited number of sites, their applicability to a broader
geographic area is limited.
Brooks and Hughes (in press) suggest using Omernik's (1987)
ecoregions as a geographic framework for the selection of
reference wetlands. They also recommend that reference sites
should be relatively undisturbed and representative of the region
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Abbruzzese et al 4
and the population of mitigation sites. A modification of their
approach was used for the Oregon pilot study.
A METHOD FOR COMPARISON SITE SELECTION
Goal of Method Development
EPA's wetlands Research Program has a project underway to
produce a handbook for evaluating proposals to mitigate for
permitted impacts on wetlands through the creation and
restoration of wetlands. Regional EPA personnel need a means of
determining the success of mitigation projects, without studying
each one in comparison to a paired site. Ideally, the results of
such studies should be applicable to a broad geographic area.
The goal of this approach is to provide EPA with an analytical
framework for setting regional goals for mitigation projects and
verifying that these goals have been met.
Rationale For The Use of a Regional Framework
Regions are relatively homogeneous areas, defined by the
coexistence of several important spatial variables (Hughes et al
1986). Ecoregions are areas with commonality In factors that
either cause variations in ecosystems .e.g., soils, climate,
physiography, or Integrate these causal factors .e.g., land use
(Omernik, 1987). Since there Ts typically less variability
within a region than between regions, regions form a logical
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Abbruzzese et al 5
fram3work from which to select representative sites, design
sampling schemes, analyze and evaluate data, and assess
attainable ecosystem quality.
Omernik's ecoregions (1987), originat'ly designed to aid in
the classification of streams, reflect regional patterns of land
use, land surface form, potential natural vegetation and soils.
They were shown to be an appropriate framework for the selection
of reference sites in studies of streams in Arkansas (Rohm et al
1987), Ohio (Larseii et al 1986), Minnesota (Heiskary et al 1987)
and Oregon (Hughes et al 1987)..These studies confirmed the
integrity of the regions. Most important, they demonstrated that
information from one part of a region could be extrapolated to
the entire region.
Wetlands and their functions are affected by many of the
same terrestrial factors important to stream function and
quality. Therefore, ecoregions were chosen as the framework from
which to select comparison sites.
Procedure
The approach has four steps: (1) delimiting the study area
In space; (2) determining relevant stratification factors; (3)
taking a random sample; and (4) conducting field reconnaissance
to eliminate highly disturbed wetlands and obtain permission to
sample candidate sites. The approach 1s first described In
generic terms, then 1n relation to its application In the Oregon
pilot study.
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Abbruzzese et al 6
Delimiting the Study Area--
The locations of the created or restored wetlands (test
sites) and ecoregion boundaries were plotted on 1:500,000 scale
state maps. The distribution of the test sites was examined
relative to ecoregion boundaries to determine which ecoregions
would be included in the study.
Determining Relevant Stratification Factors--
Test site locations and ecoregion boundaries were
transferred to 1:100,000 scale National Wetland Inventory (NWI)
maps for comparison with US Geological Survey (USGS) topographic
maps at the same scale. Sampling strata related to spatial
patterns of relief, hydrographic features, vegetative cover, and
urbanization were identified within the ecoregions of interest.
A grid, with each cell representing approximately 260
hectares (ha) was overlaid on the topographic map and cells
falling within strata relevant to the test sites were numbered
sequentially. Then the grid was transferred to the NWI map. The
parent population of comparison sites consisted of all wetlands
within the numbered cells of the grid. I.e., wetlands in sampling
str.ita comparable to the test sites (Fig. 1).
Taking a Random Sample--'
A randomized list of the sequentially numbered cells was
generated. The sample size (number of grid cells to be sampled)
was determined by calculating a progressive mean (Marsh 1978).
Groups of five cells from the random list were sampled for
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Abbruzzese et al 7
wetlands of the size and type of the test sites and the mean
number of these wetlands per cell was calculated. This procedure
was repeated until the mean number of wetland: per cell did not
change more than 0.1. Wetland type was determined using the US
Fish and Wildlife Service's wetland classification system
(Cowardin et al 1979). Wetland size was measured with a template
divided into 64 cells, with each cell equal to approximately fta.
Wetlands included in the sample were numbered sequentially
on the NWI maps and recorded on a work sheet by cell number. A
random number generator was used to determine the order in which
the numbered sites would be considered. A subset of sites was'
assembled equal to three times the number of sites needed, i.e.,
the number of test sites. Consideration of a larger number than
needed was necessary, since some of the wetlands selected would
eventually be eliminated due to alterations, severe disturbance
or because access was not permitted.
Reconnaissance of Potential Sites--
Reconnaissance, through discussions with local wetland
experts, and site visits, eliminated highly disturbed and
inaccessible sites. Permission for the field crews to take
samples at the site had to be obtained from the owner(s) of the
1 and.
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Abbruzzese et al 8
Application of Method to Oregon Pilot jtudy
In Oregon, all of the 12 test sites were located within the
Portland metropolitan arta which is situated in the Willamette
Valley Ecoregion (Fig. 2). In addition, they were all within the
most typical area of the ecoregion, i.e., the area that shares
all the terrestrial characteristics which define the ecoregion
(Omernik 1987). Therefore, the study area was the major
metropolitan areas within the most typical area of the ecoregion,
i.e., Portland, Salem, Corval1is-Albany, and Eugene-Springfield.
The boundaries of the metropolitan areas were defined by the grey
shading (used to denote urban areas) on USGS 1:100,000
topographic maps. Due to the distribution of the test sites,
Portland was treated as one unit; the rest of the urban areas
were treated as a separate unit. Theoretically, this would rcake
it possible to determine whether a set of wetlands scattered
throughout the urban areas of the ecoregion could be used for
comparison or whether subregional differences within the
ecoregion needed to be considered, i.e., each urban area is a
unique unit.
All of the test sites in the Oregon pilot study were small
(1-ha or less) palustrine emergent wetlands, I.e., marshes with
emergent vegetation (Cowardln et al 1979). Therefore, all
natural wetlands chosen for comparison were of the same size and
type. In this paper palustrine emergent wetlands 1-ha or less In
size are designated as PEM.
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Abbruzzese et al 9
RESULTS
ror the sake of brevity, only the results of the site
selection and reconnaissance in Portland are discussed here. A
total of 50 sites was randomly selected for field reconnaissance.
Table 1 shows the distribution of the Portland sites by land use.
In spite of the fact that the population of interest was located
within urban boundaries, the land use with the highest percentage
of sites was agricultural, followed by residential, commercial,
industrial and publicly owned land (Table 1).
Field reconnaissance revealed that over half (54%) of the
sites nad already been destroyed. Overall, the greatest losses
were associated with agricultural land uses (32%). Residential
development accounted for the second greatest losses, followed by
industrial land use, public land development (including
transportation) and commercial land use (Table 1).
Landowners denied access for field sampling in 35% of the
remaining 23 sites. Denial of access was greatest among
agricultural and commercial landowners, followed by Industrial
and residential landowners. The 15 sites to which EPA was
granted access constituted the final population of sites. The
distribution of these sites among the various land uses was
similar to that of the original group of potential sites (Table
1). Of the 15 final comparison sites, 12 were selected for
comparison with the 12 test sites.
The distribution of the final comparison sites in the
Portland urban area, Including associated communities, such as
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Abbruzzese et al 10
Hillsboro, Beaverton, and Gresham, was similar to that of the
.test sites (Fig. 3). Both sets of wetlands are located in
agricultural areas in the outskirts of the metropolitan area and
In the newer communities of Hillsboro and Beaverton where
population growth is occurring.
DISCUSSION
The pilot study will provide valuable data on naturally-
occurring and created wetlands, and assist in recommending
methods for conducting evaluations of such systems. Moreover,
the process of site selection, in particular the field
reconnaissance, has provided information critical to
understanding the status of wetland;, in the study area. It also
provided insight into public attitudes toward government research
on private land. These attitudes may profoundly influence the
ability to conduct similar studies in other parts of the country.
As stated previously, ecoregions are areas that share a
combination of geographic characteristics. One would expect the
wetlands within an ecoregion to have greater similarity to each
other than to wetlands of the same type 1n other ecoregions.
However, it was noted in this study that there are subreglonal
variations within the Willamette Valley Ecoregion that may
account for a higher wetland density 1n the Portland metropolitan
area than in the rest of the Valley. Portland Is at a lower
elevation and Is closer to the floodplain of the Columbia River,
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Abbruzzese et al 11
the fourth largest river system in the continental United States
(Willamette Basin Task Force Pacific Northwest River Basins
Commission 1969). Other subregional differences in wetland
structure and function may emerge when analysis of the data from
the pilot study is completed. Comparison of the Portland and
lower Willamette Valley populations will help to decermine the
extent of these differences and, therefore, the need for sets of
comparison sites unique to each urban area.
The fact that greatest loss of PEM's in the Portland urban
area is associated with agricultural land use is consistent with
general loss patterns in the United States. According to a
recent wetlands trends study, 87% of the losses between the
mid-1950's and mid-1970's were due to agricultural practices
(Tiner 1984).
The high rate of denial of access for sampling (35%) was a
frustrating complication of the site selection process.
Landowners were provided with a letter describing EPA's research
and assuring them that their names and the locations of the sites
would remain anonymous. However, this did not eliminate
concerns. A general distrust of government research or fear that
the results of the study would be used to interfere with
landowner rights was often communicated.
The selection of sites for comparison with created wetlands
in the Portland urban area did provide the required number of
sites, I.e., equal to the number of test sites being evaluated.
In addition, information derived from the field reconnaissance
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Abbruzzese et al 12
provided a basis for future analysis of trends in wetland loss.
The advantages and disadvantages of randomly selecting sites
from an ecoregion, as opposed to some more subjective approach,
should be considered before applying this method in other
studies. The random selection method offers a statistically
defensible means of obtaining a set of sites representing the
range of wetland conditions within an ecoregion. Therefore,
information from the study may be extrapolated to the total
population of wetlands of the same size and type in the
ecoregion. The estimate of the variability of natural systems
obtained can be used as a basis for evaluating wetland creation
and restoration projects and for the establishment of realistic
standards for the performance of such projects within an
ecoregion.
Furthermore, a quantitative characterization of the wetlands
can be used to improve project design. The data can be analyzed
to identify threshold values of wetland parameters where there
may be a significant positive benefit for structure, and with it,
a possible gain in function gain in function. For example, it may
be determined that when slopes are less than a certain amount
plant diversity increases dramatically and, possible, so does
life support value. Such features can then be incorporated into
plans to create or restore wetlands.
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Abbruzzese et al 13
On the other hand, the field work "involved in checking a
large number of sites and obtaining landowner permission
represents a major expenditure of time and.funds. It took two
weeks of field work for one Individual to select 15 sites. Since
access for sampling is always granted on public lands, it might
be more cost effective to limit site selection to public lands or
lands held in trust by foundations such as the Nature
Conservancy. The publicly owned sites did not seem to differ
qualitatively from sites on privately owned land. In addition,
publicly owned sites or lands held in trust are more likely to be
available for resampling at some date in the future. However,
choosing sites subjectively would place the representativeness of
the sites in question.
Analysis of the data from the field study will provide
further insight into the considerations posed above and, as a
result, the method for the selection of comparison wetlands
described in this paper will be further refined.
ACKNOWLEDGEMENTS
We wish to thank Dr. Eric M. Preston for serving as our EPA
Project Officer. Dr. Robert Hughes and Andrew Klnney provided
additional guidance. Arthur Sherman designed the graphics. We
acknowledge the cooperation of the landowners we Interviewed and
assistance from Mike Hauck and other wetland specialists in
Portland. We also thank Dr. C.D. Me Intire, Darrell Downs, and
an anonymous reviewer for their helpful suggestions and comments.
The research described In this article has been funded by the
United States Environmental Protection Agency and conducted at
EPA's Research Laboratory in Corvallis, Oregon, through Contract
#68-03-3246 to Northrop Services, Inc. It has been subjected to
the Agency's peer and administrative review and approved for
publ1 cation.
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Abbruzzese et al 14
LITERATURE CITED
Brooks, R.P. and R.M. Hughes. In press. Guidelines for
assessing the biotic communities of freshwater wetlands.
In: Proceedings of the Association of State Wetland
Managers' National Wetland Symposium: Mitigation of Impacts
and Losses. New Orleans, LA, 1986.
Cowardin. L.M., V. Carter, F.C. Golet and E.T. LaRoe. 1979.
Classification of wetlands and deepwater habitats of the
United States. US Dept. Interior, Fish Wildl. Serv.,
Washington, DC FWS/OBS-79/31. 103 pp.
Heiskary, S.A., C.B. Wilson, and D.P. Larsen. In press. Analysis
of regional patterns in lake water quality: Using ecoregions
for lake management in Minnesota. Lake and Reservoir
Management, Vol. 3. North American Lake Management
Society: Washington, DC.
Hughes, R.M., E. Rexstad and C.E. Bond. 1987. The relationship
of aquatic ecoregions, river basins and physiographic
provinces to the ichtiiyogeographi c regions of Oregon.
Copeia 1987: 423-432.
Hughes, R.M., D.P. Larsen and J.M. Omernik. 1986. Regional
reference sites: a method for assessing stream potentials.
Env. Man. 10:629-635.
Larsen, D.P., R.M. Hughes, J.M. Omernik, D.R. Dudley, C.M. Rohm,
T.R. Whittier, A.J. Kinney and A.L Gallant. 1986. The
correspondence between spatial patterns in fish assemblages
in Ohio streams and aquatic ecoregions. Env. Man. 10:815-
828.
Marsh, W.M. 1978. Environmental analysis for land use and site
planning. McGraw-Hill Book Company, NY, NY. 292 pp.
Newling, C.J. and M.C. Landin. 1985. Long-term monitoring of
habitat development at upland and wetland dredged material
disposal sites 1974-1982. Technical Report D-85-5, Dept. of
the Army, Waterways Exp. Sta., Corps of Engineers,
Vlcksburg, MS. 108 pp.
Omernik, J.M. 1987. Ecoreg1or-o of the conterminous United
States. Ann. Asioc. Amer. Geog. 77(1): 118-125. (map scale
1:7,500,000)
Paulson, G.A. 1985. Wetlands and water quality: a citizen's
handbook on how to review and comment on section 404
permits. Lake Michigan Federation, Chicago, IL. 47 pp.
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Al/bruzzese et al 15
Rohm, C.K., J.W. Giese and C.C. Bennett. 1987. Evaluation of an
aquatic ecoregion classification of streams in Arkansas.
Freshwater Ecol . 4:127-140.
Quammen. M.L. 1986. Measuring the success of wetlands
mitigation. Nat. Wetlands Newsl . 8(5):-j-8.
Shisler, J.K. and D.J. Charette. 1984. Evaluation of artificial
salt marshes in New Jersey. NJ Agr. Exp. Sta. No.
P-40502-01-84. 159 pp.
Tiner, R.W., Jr. 1984. Wetlands of the United States: current
status and recent trends. U.S. Fish and Wildlife Service,
National Wetland Inventory, Washington DC, 59 pp.
Willamette Basin Task Force-Pacifie Northwest River Basins
Commission. 1969. Willamette basin comprehensive study--
water and related land resources, Appendix B, Hydrology.
Portland, OR. 102 pp.
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Abbruzzese et al 16
Table 1. Influence of wetland loss and denial of access on the size of the
sample population of comparison sites available in the Portland urban area.
Values are a percentage of the total number (n) of sites considered at that
stage of the site selection. For example, of the 50 potential sites, 32%
were destroyed by agriculture; of the 23 remaining sites, 134 of
agricultural land owners denied access; of the final 15 comparison sites,
40* were on agricultural land. Categories of land use considered are:
agriculture (AGR), industrial (IND), commercial (COM}, residential (RES),
and public (PUB). The actual number of sites in each category is in
parentheses.
LAND USE AGR IND CON RES PUB
Potential Sites 501 (25) 10% (5) 141 (7) 181 (9) 8% (4)
(n=50)
Sites Destroyed 32% (16) 6% (3) 2% (1) 101 (5) 41 (2)
(n-50)
Access Denied 131 (3) 41 (1) 131 (3) 41 (1) 01 (0)
(n=23)
Comparison Sites 401 (6) 71 (1) 201 (3) 201 (3) 131 (2)
(n=15)
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Abbruzzese et al
17
Figure 1. Illustration of the grid used to characterize the
parent population of sites overlaid on National Wetland Inventory
(NWI) map, and two of the final comparison sites. The grid is
symbolized by th -. bold lines. The NWI map shows wetland types
(PEMY, PFOW, etc.) superimposed on a topographic map showing
roads, streams, etc. All features from the topographic map were
not included.
PEI/1Y
RFOV
PEMY\
PEMW/f
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Abbruzzese et al 18
Figure 2. Location of Willamette Valley Ecoregion ( after
Omernik 1987 } and Portland study area in Oregon.
WILLAMETTE VALLEY ECOREGION
Willamette Ecoregion
Portland Urban Area
N
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Figure 3. Distribution of test sites (created wetlands) and sites included In field
reconnaissance In the Portland urban area (composed of several communities, e.g.,
IHllsboro, Beaverton and Gresham). Sites included in the field reconnaissance are
categorized as destroyed, access denied and comparison sites. Most of the destroyed
sites are located along the urban periphery (agricultural land use) and in the
HI 11sboro-Beaverton area where urban expansion is occurring. The distribution of test
sites is similar to that of the comparison sites.
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