United States
Environmental Protection
Agency
Office of Water
(4204)
EPA 832-S-99-001
June 1999
ETI
Environmental Technology Initiative
Treatment Wetland Habitat and
Wildlife Use Assessment
June 1999
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Treatment Wetland Habitat
and Wildlife Use Assessment
Executive Summary
Prepared for
U.S. Environmental Protection Agency
Office of Wastewater Management
U.S. Department of the Interior
Bureau of Reclamation
City of Phoenix, Arizona
With funding from the
Environmental Technology Initiative Program
Prepared by
CH2M-HHI
Gainesville, Florida
June 1999
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Contents
Background 1
Scope of This Assessment 2
North American Treatment Wetland Database Version 2.0 4
Data Collection 4
Database Structure 4
Summary of NADB v. 2.0 Contents 5
Treatment of Wetlands as Habitat 6
Vegetation in Treatment Wetlands 8
Introduction 8
Plant Communities 8
Plant Species Diversity 10
Plant Dominance, Density, and Frequency 10
Primary Productivity 11
Plant Decomposition 11
Summary and Data Requirements 12
Wildlife in Treatment Wetlands 14
Introduction 14
Invertebrates 14
Fish 15
Amphibians 15
Reptiles 16
Birds 16
Mammals 18
Summary and Data Requirements 18
Toxic Metals and Trace Organics in Treatment Wetlands 18
Introduction 18
Metals 18
Trace Organics 19
Summary 19
Effects of Treatment Wetlands on Whole-Effluent Toxicity 20
Introduction 20
Acute Toxicity 21
Chronic Toxicity 21
Summary ; 21
Human Use of Treatment Wetlands 21
Activities in Treatment Wetlands 22
Nature Study 22
Exercise Activities : 23
Recreational Harvest 23
Education 23
Commercial Harvest 24
Miscellaneous Activities 24
Summary 24
in
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Contents (continued)
Treatment Wetland Design for Wildlife Habitat and Human Use 24
Introduction 24
Water Quality Considerations 25
Biological Considerations 27
Human Use 28
Summary 28
References 29
IV
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Executive Summary
Treatment
Wetland
and
Wildlife Use
Assessment
Background
Natural and constructed wetlands are being
used throughout North America and the
world to improve the quality of a broad
variety of wastewater types. Incidental to
this water quality function, most of these
wetlands attract significant wildlife
populations. In some cases, these treatment
wetlands are also open to the public for
nature study and other forms of recreation.
Little effort has been made to collect or
organize published and unpublished infor-
mation concerning the habitat functions of
treatment wetlands. As a result, many treat-
ment wetland systems have been designed
with little attention being given to achieving
plant diversity and attracting wildlife. Little
in the way of guidance has been issued on
whether such habitat creation is even com-
patible with the goal of protecting wetland
biota. While it is generally conceded that
treatment wetlands provide habitat for wild-
life, the amount and quality of that habitat
has not been widely recorded. Moreover, the
potential for this habitat to threaten the
health of wildlife attracted to treatment wet-
lands has been raised, but documentation of
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undesirable side effects has been very
limited. There are few definitive studies of
habitat values or of ecological impacts in
treatment wetlands—and when they do
exist, they are not generally available.
This Executive Summary is one output from
an Environmental Protection Agency
Environmental Technology Initiative (ETI)
Program funded and undertaken in coopera-
tion with the city of Phoenix and the
U.S. Bureau of Reclamation. This project
developed information and guidance to
facilitate treatment wetland projects that
provide multiple environmental benefits.
The potential benefits of treatment wetlands
include improved water quality, creation
of wildlife habitat, and enhancement of the
public's understanding and appreciation of
constructed wetlands. Other efforts under
the ETI project dealt with the ability of
treatment wetlands to improve water quality
and with policy and permitting considera-
tions facing the technology. This Executive
Summary and the companion report,
Treatment Wetland Habitat and Wildlife Use
Assessment, summarize what is known
about these systems in terms of their eco-
logical structure and function and how they
are used by the public. This portion of the
effort is termed the ETI Treatment Wetland
Habitat diversity can be incorporated in constructed wetlands by
planting a variety of aquatic plant species such as these -water lilies.
Habitat and Wildlife Use Assessment (ETI
Treatment Wetland Habitat Project).
Scope of This
Assessment
Natural and constructed wetlands have
received and treated wastewater from a
variety of sources for more than 25 years.
Hundreds of treatment wetlands exist in the
United States (Bastian and Hammer, 1993;
United States Environmental Protection
Agency [U.S. EPA], 1993; Kadlec and
Knight, 1996) and in Europe and Canada
(Pries, 1994). New systems are being
designed and implemented at an ever-
increasing rate. This innovative technology
for managing water quality has become
attractive to public and private facilities—
in many cases because it provides a cost-
effective method for improving water
quality while providing valuable wetland
habitat.
Concurrent with the development and
maturation of treatment wetland technology,
researchers have observed that numerous
secondary or ancillary benefits have
resulted from some of these projects
(Sather, 1989; Knight, 1992; Knight, 1997).
Published observations of high usage by
waterfowl and other wetland-dependent
wildlife in surface flow treatment wetlands
(Wilhelm et al., 1989) indicated that, in
some cases, these secondary benefits are
highly significant. Also, researchers have
pointed out potential problems that might
result from wetlands receiving wastewaters
(Gunten-spergen and Stearns, 1985;
Bastian et al., 1989; Knight, 1992; Godfrey
et al., 1985; Wren et al., 1997). Bioaccumu-
lation of heavy metals or organics that are
present in some wastewaters, as well as
transmission of disease, might create
hazards that outweigh the potential benefits
of these projects.
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The U.S. EPA conducted a pilot study of
wildlife usage and habitat functions of con-
structed treatment wetlands during the sum-
mer of 1992. This study utilized a consistent
rapid-assessment protocol at six constructed
surface flow treatment wetlands to evaluate
their habitat structure and function and the
possibility of environmental hazards
(McAllister, 1992; 1993a; 1993b). That
study represents the only known attempt to
critically compare habitat and wildlife usage
between treatment wetland sites with nearby
"control" natural wetlands.
A recent report prepared by the Canadian
Wildlife Service (Wren et al, 1997) sum-
marizes information on wildlife usage of
stormwater treatment wetlands. It identifies
areas of potential concern related to
accumulation of hazardous pollutants and
concludes that insufficient data are available
to document detrimental effects. The report
recommends the need to require detailed
monitoring of potential wildlife hazards in
stormwater treatment wetlands in Canada.
This ETI project effort represents the first
comprehensive effort to assemble the wide-
ranging information concerning the habitat
and wildlife use data from surface flow
treatment wetlands. These data are
assembled in an electronic database that
allows researchers to take a critical look at
the actual benefits and hazards that have
been documented in treatment wetlands.
This project involved a focused search of
project reports and researcher files for quali-
tative and quantitative information con-
cerning surface flow treatment wetland
plant communities, animal populations,
concentrations of trace metals and organics,
biomonitoring results, and human use.
These data have been gathered into an
electronic format built upon the previous
existing North American Treatment Wetland
Database Version 1.0 (NADB v. 1.0) funded
by U.S. EPA (Knight et al., 1993). This
Executive Summary briefly describes the
format and contents of the updated database
(NADB v. 2.0) and synthesizes this existing
information into a summary of current
knowledge and remaining questions related
to habitat and wildlife use of treatment
wetlands.
Gated pipes on
raised boardwalks
allow access to
more than 600 acres
of treatment area in
the Vereen Natural
Treatment Wetland
in South Carolina.
Habitat quality, wildlife population, and
human usage data have been previously
collected by a number of treatment wetland
projects. When available, these data are
typically in raw form, unpublished reports,
or rarely in peer-reviewed publications. In
many cases, these data have not been avail-
able to other researchers to evaluate. No
previous attempt has been made to assemble
these types of data into a consistent format
or to summarize information to compare
results among treatment wetland sites.
The primary purpose of this effort was to
assemble existing wildlife and habitat use
data from diverse sources into a consistent
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format and to make these data available to
regulators, designers, owners, and
researchers. This Executive Summary and
the companion report provide a preliminary
summary of these data to begin identifying
any apparent benefits or hazards. It is
anticipated that others will conduct more
detailed analyses of these data.
A second purpose of this effort was to
establish an inventory of the types of data
that are of interest when assessing the
environmental and societal attributes of
treatment wetlands and to create a database
format to guide the design of new studies as
additional data are collected by wetland
researchers. A third purpose of the effort
was to provide information concerning
habitat value, wildlife and human use in
treatment wetlands to be used for future
designs of these systems to optimize spe-
cific goals for habitat creation. Another
purpose of this project was to identify areas
of insufficient knowledge and to recom-
mend actions that can be taken to fill those
information gaps.
North American
Treatment Wetland
Database Version 2.0
(NADB v. 2.0)
Data Collection
The original NADB v. 1.0 identified
179 sites where treatment wetlands were
being used in North America (Knight et al.,
1993). In the course of that effort, habitat
and wildlife usage data sets were obtained
from some of these sites. Ongoing treatment
wetland monitoring projects continue to
develop habitat-related data, and those data
were requested by telephone and or in
writing from current project owners and
researchers. Data were received in various
formats, including electronic spreadsheets,
consultant and owner reports, daily
monitoring reports, and raw data. Data were
collected using a variety of methods with no
differing levels of quality control/quality
assurance between projects. Although this
effort to obtain existing treatment wetland
habitat data was extensive, it is considered
likely that some relevant data sets are not
included in this survey.
There was no attempt to verify or judge the
quality of data collected for this database.
Any use of these data to develop summary
conclusions concerning the populations of
flora and fauna in treatment wetlands
should be considered preliminary until
specific data sets are identified and their
quality verified through peer-reviewed
reports. The data gathered for the com-
panion report range in quality from detailed
biological and water quality research efforts
to cursory qualitative estimates. For most
purposes, the data summarized in the
NADB v. 2.0 can be assumed to be reason-
able estimates of the biological and chemi-
cal conditions in these treatment wetlands.
Database Structure
Five new database files with data pertinent
to habitat quality and wildlife use of treat-
ment wetlands were added to the existing
seven files in NADB v. 1.0 to create the
ETI Treatment Wetland Habitat Project
NADB v. 2.0. The structure of the five new
database files follows the format of
NADB v. 1.0 in their hierarchical structure.
The NADB v. 2.0 also has been updated by
adding treatment wetland site, design, and
operational performance data from confined
animal feeding operations (CAFOs)
summarized by a separate project completed
for the Gulf of Mexico Program with
U.S. EPA funding (CH2M HILL and Payne
Engineering, 1997).
Each record identifies the treatment
wetland site, system, and cell, which allows
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Legend
ETI Habitat Database
Site
System
Cell
ETI U.S. EPA
Environmental
Technology
Initative
File structure of the North American Treatment Wetland System Database Version 2.0.
links between the 12 individual database
files in NADBv. 2.0.
The Vegetation database file contains quali-
tative and quantitative plant community
data for treatment wetland sites. It provides
vegetation data of cells within each system
for a specified period. Data entered here in-
clude species lists, percent cover, biomass,
density, basal area, and importance values.
The Wildlife database file contains quali-
tative and quantitative population data for
benthic macroinvertebrates (benthos), fish,
amphibians, reptiles, avifauna (birds), and
mammals. Data entered here include species
lists, species density, species diversity, and
reproductive success for a given period.
The Metals/Organics database file contains
data on water, sediment, plant, and wildlife
tissue concentrations for trace metals and
organics. Data entered into this file are iden-
tified by the sample matrix type (water, sed-
iment, or tissue) and the sample parameter.
Water sampling data are recorded as influ-
ent and effluent concentrations for each
system at a given site. Sediment data are
identified by the station location. Plant
and wildlife tissue data are identified by
species and the type of tissue.
The Biomonitoring database file includes
information on acute and chronic toxicity
tests, reproduction, and mortality tests on
various test organisms. Each record iden-
tifies the sampling location (influent or
effluent), dilution for each test, and the
organism used.
The Human Use database file contains
information on how the public uses wetland
treatment sites for recreation, research,
hunting, and other activities. Data entered
include use density, number of use days,
and harvest totals per site.
Summary of NADB v. 2.0
Contents
NADB v. 2.0 has information for a total of
257 sites, 367 systems, and 831 cells from
treatment wetlands in North America. These
numbers reflect the fact that some sites have
multiple systems and some individual sys-
tems have multiple cells. Of these 257 sites,
160 receive and treat municipal wastewater,
12 receive industrial effluents, 68 receive
livestock wastewaters, and 17 receive other
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wastewater types including stormwaters. Of
the systems described inNADB v. 2.0,
305 are surface flow, 54 are subsurface
flow, and 8 are hybrids of these two designs.
The five new files in NADB v. 2.0 contain
habitat and related data for 109 sites,
168 separate systems, and 386 individual
cells from 31 states or provinces. Eighty-
five percent of the sites within the five new
database files are constructed treatment
wetlands; the rest are natural treatment
wetlands. Of the 29,960 new records in
these five database files, 65 percent come
from constructed treatment wetland sites.
Treatment Wetlands
as Habitat
The word habitat refers to a place or envi-
ronment that provides support for the needs
of a plant or animal. Many plant species are
typically found in wetland environments,
including vascular plants, algae, mosses,
ferns, and other nonvascular plant species.
Wetlands also provide some or all of the
habitat requirements for thousands of
animal species. Some animals may live out
their lives within the border of a particular
wetland, while other species are adapted to
come and go across wetland boundaries.
Wetlands provide significant habitat
requirements for many of the bird species
commonly found in North America.
For an environment to be classified as
habitat for a particular organism, it must be
able to provide the necessary conditions
required to complete the normal life cycle of
that organism and to propagate the species
into the indefinite future. There must be the
opportunity for reproduction, growth, adap-
tation, maturation, and, ultimately, repro-
duction again.
there is no single measure of the adequacy
of habitat that can be applied broadly across
many species. However, there is a relatively
simple test to determine if a given area is
providing suitable habitat for a species of
interest. The presence of the species over a
period of time that includes multiple gener-
ations indicates that the area is suitable
habitat. For plant populations, this test
requires that successful reproduction must
occur within the plant's normal life span.
This might be only once in 100 years for
long-lived tree species, or it may be yearly
for annual species.
This habitat test applies to organisms that
breed within the habitat as well as those that
may migrate through and breed elsewhere.
If these migratory animals or their progeny
do not return to the area, then it is not pro-
viding suitable habitat. To be beneficial,
habitat must provide one or more life
history requirements that contribute to a
species' sustainable population size. If the
amount or quality of available habitat is
limiting a given species' overall population
size, then the addition of more habitat or the
enhancement of existing habitat will lead to
a higher sustainable population of that
organism. While science may never have
enough information to define a species'
overall population size and the variable
nature of that population from year to year,
enough data exist for some key species that
occur in treatment wetlands to make pre-
liminary assessments of the habitat value of
these engineered ecosystems. Existing
knowledge can be organized by taxonomic
group (vegetation and animals) and by
specific attention to potential hazards to
biota and humans.
Since the habitat requirements of nearly
every organism are different in some way,
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Treatment Wetland Sites in theNADB Version 2.0 with Habitat Data.
Site No.
1
5
7
g
11
12
13
18
20
22
25
26
29
31
33
39
51
62
68
76
•91
92
96
98
99
102
108
109
110
111
112
114
202
204
206
209
210
217
302
303
304
310
311
312
314
412
500
501 ,
502
503
504
505
506
507
508
509
510
Site Name
Lakeland, FL
Orange County, FL
Cypress Domes, FL
Reedy Creek, FL
Silver Springs Shores, FL
Central, SC
Ironbridge, FL
West Jackson County, MS
Poinciana, FL
Vereen, SC
Arcata, CA
Hillsboro, OR
Santa Rosa, CA
Waldo, FL
Deer Park, FL
Brookhaven, NY
Hayward, CA
Wlinot, ND
Halsey (Pope & Talbot), OR
Show Low, AZ
Hillsboro, ND
Everglades Nutr. Removal, FL
Columbia, MO
Hemet/San Jacinto, CA
Sacramento Dem. Wetland, CA
Champion Pilot, FL
Las Gallinas San. Dist., CA
Collins, MS
Tompkins County Landfill, NY
TVA Mussel Shoals, AL
Tres Rios, AZ
Tarrant Co, TX
Biwabik, WIN
Cannon Beach, OR
Des Plaines, IL
Houghton Lake, Ml
Kinross (Kincheloe), Ml
Vermontville, Ml
Benton, KY
Brillion, Wl
Drummond, Wl
Incline Village, NV
Listowel Artificial Marsh, ONT
MtView Sanitary District, CA
Seneca Army Depot, NY
Benton, KY
Saint-Felicien, QUE
Essex County, ONT
Perth County, ONT
Simco County No. 1, ONT
Region of Niagara, ONT
Hamilton-Wentworth, ONT
Region of Ottawa-Carlton, ONT
Russel County, ONT
Region of Peel, ONT
Simco County No. 2, ONT
Lucky Rose Farm, IN
Origin
CON
CON
NAT
NAT
CON
NAT
NAT
CON
NAT
NAT
CON
CON
CON
NAT
NAT
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
NAT
NAT
CON
NAT
NAT
CON
CON
NAT
NAT
CON
CON
CON
NAT
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
Area in
Hectares
498.00
89.00
'1.56
82.20
21.00
31.60
494.00
22.70
46.60
229.00
15.18
35.70
4.05
2.60
50.60
0.49
58.68
13.58
2.02
54.20
33.00
1,406.00
37.00
14.16
8.90
1.42
—
4.47
0.04
0.19
4.18
—
40.50
7.00
10.13
79.00
110.00
4.60
3.00
156.00
6.00
173.28
0.87
37.00
2.50
1.46
0.72
0.06
0.09
—
0.02
0.02
0.08
—
0.03
0.98
Source of
Waste Water
MUN
MUN
MUN
MUN
MUN
MUN
MUN
MUN
MUN
MUN
MUN
IND
MUN
MUN
MUN
MUN
MUN
MUN
IND
MUN
IND
OTH
MUN
MUN
MUN
IND
MUN
MUN
IND
IND
MUN
OTH
MUN
MUN
OTH
MUN
MUN
MUN
MUN
MUN
MUN
MUN
MUN
MUN
MUN
MUN
MUN
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
Site No.
511
512
513
514
515
516
517
518
519
520
521
522
523
524
526
527
528
529
530
531
532
533
536
537
538
539
542
543
544
545
546
547
548
549
550
600
601
602
603
605
' 606
607
608
610
611
612
613
615
616
617
Site Name
Wayne White Farm, NS
David Thompson Farm, NS
Ken Hunter Farm, NS •£•
Oregon State University, OR
Hickok Veal, PA
Cobb Farm, PA
MoyerFarm, PA
Crum Farm, MD
3M Farm, MD
Delmarva Farms , MD
U of Connecticut, CT
Guy Thompson Farm, PEI
David Gerrits Farm, Wl
Norwood Farms, IN
Nowicki Farm, ALB
Mercer Co., KY
Piscataquis River, ME
Tom Brothers Farm, IN
Purdue University, IN
AdairCo. No. 1,KY
AdairCo. No. 2, KY
Casey Co. No. 1 , KY
Crittenden Co., KY
Wayne Co. No. 1,KY
Wayne Co. No. 2, KY
Spencer Co., KY
Allen Co., KY
Butler Co. No. 1,KY
Hopkins Co., KY
McLean Co. No. 1,KY
McLean Co. No. 2, KY
McLean Co. No. 3, KY
Union Co., KY
Butler Co. No. 2, KY
Dogwood Ridge, KY
Hernando, MS
Pontotoc, MS
Newton, MS
Hattiesburg, MS
Auburn Poultry, AL
Auburn Swine, AL
McMichaei Dairy, GA
Tifton, GA
Louis. St. Univ., LA
New Mexico State, NM
Duplin, NC
Key Dairy, GA
Crittenden Co., KY
Union Co., KY
La Franchi, CA
Origin:
CON
NAT
HYB
Constructed
Natural
Hybrid
1 hectare (ha) = 2.47 acres
Origin
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
CON
Area in
hectares
0.43
0.10
0.07
0.53
0.14
0.01
0.01
0.11
0.12
0.73
0.04
0.15
0.03
0.11
0.05
0.14
0.04
0.19
0.03
0.03
0.04
0.06
0.07
0.03
0.02
0.04
3.70
4.90
0.93
0.65
0.28
0.12
0.12
4.80
3.80
0.08
0.32
0.12
1.24
0.12
0.00
0.29
0.22
0.81
0.00
0.07
0.35
0.34
0.10
0.10
Source of
Waste Water
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
AGR
Source of Waste Water:
AGR
IND
MUN
OTH
Agricultural
Industrial
Municipal
Other
7
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8
Cattails continue to be the -workhorse of many
treatment wetlands.
Vegetation in Treatment
Wetlands
Introduction
The wetland environment is generally char-
acterized by a high diversity and abundance
of plants (Mitsch and Gosselink, 1993). In
many cases, wetland plant communities
include multiple vertical strata ranging from
groundcover species to shrubs and sub-
canopy trees to canopy tree species. Obligate
wetland plant species are defined as those
found exclusively in wetland habitats, while
facultative species are those that may be
found in upland or wetland areas. The
U.S. Fish and Wildlife Service (USFWS) has
listed more than 6,700 species of obligate
and facultative wetland plant species in the
United States (Reed, 1988).
Wetland plant diversity is important in deter-
mining wildlife diversity because of the
creation of niches associated with differing
vegetative structures, reproduction strate-
gies, flowering and seeding phenologies,
gross productivity, and rates of decomposi-
tion. In addition to their diversity of species
and growth habitats, wetland plants are
important for treatment wetland pollutant
removal performance because the physical
and chemical structure they provide
supports microbial populations.
The ecology of wetland plant communities
can be assessed through the use of quali-
tative and quantitative measures. Lists of
plant species provide an overall qualitative
inventory of the diversity that is present and
the ability of a wetland plant community to
adapt to fluctuating environmental condi-
tions. Quantitative measures of dominance
(mass or cover per unit area), density (num-
ber of individuals per unit area), and fre-
quency (percent occurrence in a number of
different samples) of plant species are direct
indicators of ecological structure and can be
compared between treatment wetlands and
control sites to assess differences. Quanti-
tative functional measures of wetland plant
populations include primary productivity
(gross and various measures of net produc-
tivity), litterfall, and decomposition. These
measures provide a method to compare the
functions of constructed and natural treat-
ment wetlands and to compare treatment
wetlands with control wetlands that are not
receiving treated effluents.
Plant Communities
Constructed treatment wetlands are typi-
cally dominated by emergent marsh, float-
ing aquatic plant, or submerged aquatic
plant communities. In some cases, these
constructed treatment wetlands are domi-
nated by populations of filamentous algae
because marsh plant species have had dif-
ficulty becoming established. Emergent
marsh species are frequently intermingled
and co-dominant with populations of small
floating aquatic plants such as duckweed
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110
Lake/Freeway Barrier Reached
1990
1
Increasing dominance by cattails
(Typha latifolia) at the Kinross,
Michigan, natural -wetland. The
original plant dominants were bog
birch (Betula pumila). sedge (Carey,
flava). and black spruce (Picea
mariana). Approximately one-third
of the entire wetland area (320 ha)
was altered by this unplanned
treatment project. Water depth
changes resulting from beaver
activity were implicated, in addition
to nutrient inputs, as an important
causative factor for this shift in
plant dominance (modifiedfrom
Kadlec and Bevis, 1990).
(Lemna spp.). Many constructed treatment
marshes in the United States are dominated
by cattails (Typha spp.) or bulrush (Scirpus
spp.); however, some treatment marshes are
dominated by other plant species or by a
complex admixture of species that includes
cattails and bulrush.
Natural wetlands used for water quality
treatment may be dominated by emergent
marsh plant species, by tree species, or by
shrub species. Dominant species in natural
wetlands used for water quality treatment
vary regionally, depending upon the types
of wetlands that are locally available. In the
Southeastern United States, the dominant
forested wetland types used to receive and
polish wastewaters include cypress (Taxo-
dium spp.), gum (Nyssa spp.), bay (Gor-
donia lasianihus, Magnolia virginiana,
and/or Persea spp.), red maple (Acer
rubrutri), titi (Cyrilla racemiflora and
Cliftonia monophylla), willows (Salix spp.),
ash (Fraxinus spp.), and oaks (Quercus
spp.). hi the Northcentral United States,
forested wetlands receiving wastewaters are
dominated by spruce (Picea spp.), willow,
and birch (Betula spp.). In the Northwestern
United States, natural shrub forested wet-
lands that receive treated wastewaters are
dominated by alder (Alnus rubrd) and sitka
spruce (Picea sitchensis).
In the upper Midwest and Northeastern
United States, natural marshes dominated
by cattails, grasses, and sedges have re-
ceived a variety of wastewater discharges.
Many constructed and natural treatment
wetlands undergo plant succession during
their operational life. Constructed marshes
tend to remain marshes as long as flooding
is nearly continuous and water depths ex-
ceed about 5 centimeters (cm). At shallower
water depths and under conditions that
allow germination of woody species (such
as at Orange County, Florida, Site No. 5),
plant succession moves from herbaceous
marsh plant species, through shrubs and
small trees, to a forested wetland.
Natural treatment systems may undergo
succession also. Observed succession in the
immediate vicinity of the distribution area at
the Bear Bay wetland near Myrtle Beach
(Vereen, Site No. 22), South Carolina, and
in forested wetlands in north-central Mich-
igan (Bellaire, Site No. 201 and Kinross,
Site No. 210) was from densely forested to
open forest shrub/marsh. The water regime
and nutrient quality conditions at these
wetlands killed sensitive tree species and
promoted growth of herbaceous and woody
ground cover and shrubs. Other forested
natural treatment wetlands have continued
-------
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their normal maturation pattern as indicated
by increasing tree basal area over time.
Plant Species Diversity
Of the more than 800 species of macro-
phytic plants reported in natural and con-
structed treatment wetlands, 693 species are
emergent herbaceous macrophytes, 36 are
floating aquatic species, 12 are submerged
aquatics, 57 are shrubs, 55 are trees, and
18 are vines. A total of 593 macrophytic
plant species has been reported from con-
structed treatment wetlands and 427 species
from natural treatment wetlands. Emergent
herbaceous macrophytes account for
501 species in constructed treatment wet-
lands and 290 species in natural treatment
wetlands. A significant variety of tree and
shrub species occurs in some constructed
wetlands. Tree and shrub species are well
represented in natural treatment wetlands
with 88 different species recorded.
Plant Dominance, Density, and
Frequency
Emergent herbaceous plant communities
can be quantitatively sampled by use of
line-intercept transects or quadrants. These
plant ecology techniques provide measures
of plant cover by species, plant frequency,
and, in some cases, plant density, height, or
biomass. Plant communities in forested wet-
lands are often quantified through measure-
ments of dominance, density, and frequency.
These three quantitative measures can be
used to calculate importance value, a rela-
tive measure of the contribution of indi-
vidual tree species in a forest.
Quantitative data from treatment wetlands
confirm the common observation that
Biological criteria in the Vereen Natural Treatment Wetland near Myrtle Beach, South Carolina (Site No. 222) include
allowable changes for canopy density and dominance, subcanopy and shrub percent cover, and total plant species
diversity. While decreases have been observed for one of these criteria (subcanopy and shrub percent cover), the other
three criteria have all increased in response to 10 years of treated municipal effluent discharge. Far from becoming a
monoculture, thefloristic diversity of this -wetland has increased by 14 species; and overall canopy dominance has
increased by 250 percent.
10
-------
Discharge Area at Pipeline
Backgradient Control Area
Plant biomass changes in response
; to addition of treated municipal
\ effluent at Houghton Lake
Peatland. Control area experiences
; hydrologic changes without
nutrient increases. Pre-existing
peatland vegetation was largely
•' replaced by cattails and duckweed
* dominants over about one-tenth of
* the 600-ha area (modifiedfrom
| Kadlec, 1993).
these systems are densely vegetated. Plant
biomass values are at the high end of re-
corded values in nontreatment wetlands.
This is the case in both constructed and
natural treatment wetlands. Reductions in
tree dominance have been observed in a
number of natural treatment wetlands,
while others show no detrimental effect.
Effects on wetland trees are species
specific. Some tree species are adapted to
the long hydroperiods and low sediment
oxygen levels typical of treatment
wetlands, while other species cannot
survive these changes. An understanding of
the tolerance limits of individual plant
species, careful site selection, and project
design can maintain high tree dominance
in natural treatment wetlands.
Primary Productivity
Biomass estimates in marsh wetlands pro-
vide an index of net plant productivity on a
seasonal basis. The biomass estimates in the
NADB v. 2.0 indicate that treatment wet-
land marshes have high net production
compared with many nontreatment marshes.
No direct estimates of net primary produc-
tivity were recorded in NADB v. 2.0. How-
ever, the database includes litterfall rates
from two natural forested wetlands (Orange
County, Florida, Site No. 5, and Bear Bay,
South Carolina, Site No. 22). Litterfall may
be used as a measure of net primary produc-
tion (Mitsch and Gosselink, 1993). The lit-
terfall rates summarized from treatment
wetlands are comparable to values from
natural forested wetlands and adjacent
natural control wetlands.
Plant Decomposition
Litter decomposition rates measure an
important component of carbon and nutrient
Orange Co., FL
Eastern Service
: Area
Bear Bay,
SC
Average of
20 SE.
Deepwater
Swamps
Average of 5
.. Ffoodplain
Forested
Wetlands .
Litterfall rates provide an estimate of net primary productivity
in wetlands dominated by woody vegetation. Rates in natural
treatment wetlands are comparable to unaltered natural
wetlands.
11
-------
recycling in wetlands. The decomposition
rates of individual plant species differ
greatly because of their variable cell struc-
ture and lignin composition. Litter decom-
position rates are available hiNADB v. 2.0
from two treatment wetlands—Bear Bay in
South Carolina (Site No. 22) and the
Orange County Eastern Service Area in
Florida. At both sites, the presence of shal-
low flooding caused by the discharge of
treated effluent increased the decomposition
rate of leaves.
Summary and Data Requirements
Treatment wetlands are typically dominated
by dense growths of wetland-dependent
plant species. These plant communities are
similar in ecological structure and function
to natural wetland plant communities.
Volunteer plants such as these mud-plantain frequently
invade constructed treatment wetlands, adding habitat
diversity for wildlife and greater resistance against
insect infestations in cattail-dominated marshes.
A variety of plant communities occurs in
treatment wetlands, including marshes,
shrub swamps, and forested swamps. While
most constructed treatment wetlands are
marshes, a few constructed treatment sys-
tems are developing shrub and swamp
characteristics over time, either inten-
tionally or through volunteer plant coloni-
zation and succession.
On the other hand, natural forested wet-
lands receiving secondary treated municipal
wastewaters have been partially converted
to marshes in several areas of the United
States. Other forested wetlands receiving
higher quality municipal wastewaters
(advanced secondary with nitrification or
tertiary with phosphorus removal) have
maintained their canopy dominance over
significant periods of time.
More long-term, ecosystem-level studies
are needed for both constructed and natural
treatment wetlands under a variety of geo-
graphical and pollutant loading conditions
to fully describe the parameters most pre-
dictive of plant community development in
treatment wetlands. Also, more studies of
the basic quantitative ecology of natural
wetlands would be helpful for comparison
to treatment wetland structure and function.
Wetland plant diversity is a poorly under-
stood subject, both in unaffected natural
wetlands and in treatment wetlands. Non-
treatment natural wetlands are frequently
dominated by only a few plant species (for
example, cypress swamps, cattail, sedge, or
sawgrass marshes, etc.) that are best adapted
to stressful environmental conditions such
as low nutrient levels, low soil oxygen
levels, or fluctuating water levels. Other un-
affected natural wetlands have higher plant
diversity and greater evenness between
multiple dominant plant species.
Both constructed and natural treatment
wetlands cover the same range of plant
12
-------
dominance and diversity of unaffected
natural wetlands. Information collected for
NADB v. 2.0 indicates that hundreds of
plant species occur in a variety of treatment
wetlands. Even when treatment wetlands
are dominated by cattails or bulrush, dozens
of other herbaceous and woody plant
species are typically present.
Data from natural treatment wetlands indi-
cate variable responses to treated effluent
discharges. For example, existing diversity
may be reduced by the presence of a,waste-
water discharge (e.g., Houghton Lake, Site
No. 209, and Kinross, Site No. 210, Mich-
igan), or diversity may be maintained or
increased following the initiation of a dis-
charge to other wetlands (Orange County
and Reedy Creek, Florida, and Bear Bay,
South Carolina).
The effect of treated wastewater discharges
on plant diversity in natural wetlands de-
pends on the amount of pre-treatment and
the scale of the project. Municipal effluents
treated to advanced standards generally
have only a water regime effect, while those
treated to secondary standards may also
have a water quality effect. Water quality
effects on plant diversity are greatest near
the point of inflow, while water regime
effects may occur over the entire area of a
natural treatment wetland. Over the scale of
the entire wetland, plant diversity may be
increased by the addition of new plant
species associated with the discharge.
Total plant cover and dominance data do not
indicate any observable difference between
treatment and nontreatment wetlands for
these indices. However, biomass data indi-
cate that discharge of secondary municipal
wastewater to natural, low-nutrient wetlands
will greatly increase plant biomass. This
enrichment effect is typical of wetlands
receiving treated municipal discharges and
is most observable in the immediate area of
the discharge.
Very few data have been collected that mea-
sure the ecological function of treatment
wetland plant communities. High plant
growth rates are apparent based on standing
crop; however, clip plots, gas metabolism
studies, litterfall studies, or other methods
for estimating net primary production have
been conducted at only a few locations. Lit-
terfall rates in at least two natural forested
treatment wetlands are comparable to unaf-
fected natural forested wetlands.
Other ecological functions related to the
carbon cycle through wetland plants have
been largely ignored in treatment wetland
studies. Decomposition rates in treatment
wetlands compared with natural wetlands
appear to be higher because of greater or-
ganic carbon inputs and the continuous
presence of water. The proportion of this
organic carbon cycling through the wetland
plants may be very different between treat-
ment and nontreatment wetlands, and the
quantities and forms of carbon being ex-
ported across the system's boundaries are
likely to be different. More comprehensive
studies of the total carbon cycle in treatment
wetlands would help quantify the relative
importance of these similarities and
differences.
Dragon/lies are a common predator found at both
constructed and natural treatment wetlands.
13
-------
Wildlife in Treatment
Wetlands
Introduction
Numerous wildlife species of all taxonomic
orders depend on wetlands as habitat. Plant
productivity and imports of organic carbon
from surrounding ecosystems provide the
energy basis that supports these wildlife
populations. Many wetlands have both
aquatic and terrestrial food chains. Plant
tissues that fall into the aquatic portion of
the wetland are typically degraded by a
complex assemblage of microscopic and
small aquatic organisms that includes
invertebrate animal groups (protozoans,
worms, molluscs, arthropods, and others).
These organisms, in turn, serve as the basis
of the food chain for other invertebrates and
for diverse vertebrate groups such as fish,
amphibians, reptiles, birds, and mammals.
In addition to their direct support of wildlife
food chains, wetlands provide diverse
structure for other wildlife habitat needs.
Wetland
monitoring efforts
have charterized
all biotic
communities in
constructed
treatment wetlands,
including
macroinvertebrates.
14
More than 1,400 species of wildlife have
been reported for constructed and natural
treatment wetlands in the NADB v. 2.0.
These include more than 700 species of
invertebrates, 78 species offish, 21 species
of amphibians, 31 species of reptiles,
412 species of birds, and 40 species of
mammals. More than 800 animal species
have been reported in constructed treatment
wetlands alone. Because species lists have
been determined for only a small fraction
of the treatment wetland sites listed in
NADB v. 2.0 and because of the widely dis-
parate methods and seasons of measurement,
these species totals underestimate the diver-
sity that exists in treatment wetlands in
North America. The sections that follow
describe findings for each wildlife group
individually.
Invertebrates
A total of 709 species of aquatic inverte-
brates have been recorded from treatment
wetlands in NADB v. 2.0. These include
15 species of aschelminthes, 81 species of
crustaceans, 12 species of arachnids, 29 spe-
cies of molluscs, and 589 species of insects.
Twenty-three treatment wetland systems
listed in NADB v. 2.0 have invertebrate data.
In most cases, only species lists are avail-
able. A few systems reported quantitative
data, although sampling techniques varied.
Although a total of 342 species of benthic
macroinvertebrates have been reported for
constructed treatment wetland sites, the
average diversity (H') is low at 1.36 units.
The average benthic macroinvertebrate
diversity for natural treatment wetlands is
2.29 units with a total of 349 species re-
ported for all sites. These low diversities are
typical of unaltered wetland environments
due to low ambient dissolved oxygen levels
and fluctuating water availability.
Average benthic populations summarized
in the NADB v. 2.0 are 6,083 individuals per
square meter for constructed treatment
-------
wetlands and 2,102 per square meter for
natural treatment wetlands. Total popula-
tions of mosquito larvae and pupae in treat-
ment wetlands are reported from a few
projects. Average densities are 1,144 indi-
viduals per cubic meter for constructed
treatment wetlands (pilot wetlands in
Hemet, California, Site No. 98, and Sacra-
mento, California, Site No. 99) and 952 per
cubic meter in natural treatment wetlands.
The range of values around these averages
is great and may reflect differences in sam-
pling techniques as much as differences be-
tween actual wetland mosquito populations.
No functional measures for invertebrate
populations were discovered from treat-
ment wetland studies. Secondary production
of invertebrates can be evaluated by using
repeated population estimates through time.
General anecdotal observations from newly
constructed treatment wetlands indicate that
invertebrate populations develop quickly
when treated wastewaters are added and
that these population trends are highly var-
iable when vegetative cover changes during
the first few seasons of wetland maturation.
Long-term populations of invertebrates
appear to be more stable and more charac-
teristic of natural wetland environments.
Fish
Seventy-eight fish species are reported
from 13 treatment wetland sites in
NADB v. 2.0 (64 species from constructed
treatment wetlands and 24 species from
natural treatment wetlands). Mosquitofish
(Gambusia affinis) were reported from five
constructed and four natural treatment wet-
lands. This species, found in 69 percent of
the treatment wetlands where fish were
sampled, is often intentionally introduced
into these treatment wetlands; other species
are apparently present as a result of volun-
teer colonization.
Snakes such as this
-water moccasin are an
Important link in the
food -webs of treatment
wetlands.
Amphibians
Twenty-one amphibian species are reported
from six constructed and three natural
treatment wetlands in the NADB v. 2.0.
Ten species are reported from constructed
treatment wetlands and 14 species from
natural treatment wetlands. Amphibian
species occurrence was recorded at two
natural treatment wetland sites in South
Carolina, but populations were not quan-
titatively sampled. From four to eight am-
phibian species were observed each year
during 7 years of operation of the Vereen
natural treatment wetland (Site No. 22).
From four to seven amphibian species were
observed over 3 years at Central Slough
(Site No. 12). The likely amphibian diver-
sity at these two locations is greater than
these numbers indicate since sampling was
qualitative and conducted over a limited
period during the spring of each year. No
quantitative data on amphibian populations
are included in the database.
15
-------
Reptiles
Thirty-one reptile species are reported from
five constructed and four natural treatment
wetlands in NADB v. 2.0. These species in-
clude snakes, alligators, lizards, and turtles.
Seven species are reported from constructed
treatment wetlands and 28 species from
natural sites. The Vereen site in South
Carolina (Site No. 22) had between six and
nine reptile species while Central Slough
(Site No. 12) had between one and six
species. As with the amphibian data above,
reptile diversity at these sites is likely
greater than what is reflected by these num-
bers. No quantitative data on reptile popula-
tions are included hi the database.
Birds
Bird data are reported for 21 constructed
treatment wetland sites and 7 natural treat-
ment wetland sites in the NADB v. 2.0. The
majority of these data are species lists and
population densities. Very few data on
breeding success, nesting, brood production,
and mortality rates were found for this
review.
A total of 412 bird species are reported from
these treatment wetlands. Constructed treat-
ment wetlands are represented by 361 bird
Bird diversity and density in treatment wetlands are
typically high.
Number Average
Observed Density
Site Name Species (#/ha)
Constructed Wetlands
Lakeland, FL
West Jackson County, MS
Arcata, CA
Hayward, CA
Show Low, AZ
Collins, MS
Tres Rios, AZ
Incline Village, NV
Natural Wetlands
Gainesville, FL
Vereen, SC
Biwabik, MN
Houghton Lake, Ml
190
61
159
134
155
35
78
53
20
103
46
68
6
10
61
114
14
7
2,958
19
23
19
13
23
species and natural treatment wetlands by
170 bird species. Of the bird species listed,
51 are waterfowl, 23 are wading birds,
24 are terns or gulls, 45 are shorebirds, 29
are raptors or scavengers, 7 are fowl-like,
and 235 are passerine or non-passerine land
birds. Approximately 45 percent of the total
of 412 species reported from treatment wet-
lands are commonly considered to be
wetland-dependent for some portion of their
life history. This finding indicates that a
majority of the bird species recorded at
these treatment wetland sites are facultative
wetland inhabitants.
Bird species counts and population densities
vary between sites, and even at a single
treatment wetland site on a seasonal basis.
For example, the Hayward marsh (Site
No. 51) in California recorded population
densities ranging from 34 to 280 birds per
hectare during monthly counts. Two demon-
stration-scale constructed wetlands are
being studied at the Tres Rios, Arizona (Site
No. 112), constructed treatment wetland.
Bird species numbers by month for the Hay-
field and Cobble sites reflect this variability,
and total species counts for a year are much
higher than for any individual month
(61 species at the Cobble site and 66 species
at the Hayfield site). These two sites are less
than 0.5 mile apart and have very similar
surface areas and plant communities, but are
adjacent to different natural riparian
systems. Total bird densities averaged
295 birds per hectare at both sites. These
high densities are dominated by yellow-
headed blackbirds (Xanthocephalus xantho-
cephalus) with about 1,503 birds per hec-
tare. Bird population densities in natural
riparian hibitats in the same area are much
lower than the average bird densities
measured at the Tres Rios wetlands.
Bird populations were studied at the
Des Plaines, Illinois (Site No. 206), con-
structed treatment wetlands before and after
16
-------
project startup. A total of 22 species was
observed during the breeding season in 1985
before construction began, and from 30 to
37 species were observed during breeding
season counts in 1990 and 1991. Spring
migration waterfowl and wading bird counts
were also made at this wetland. The number
of waterfowl species observed during the
first 7 weeks of migration rose from 3 to 14
(1990) prior to project startup and 15 (1991)
species with the project. Total waterfowl and
wading bird densities at this site were be-
tween 691 and 929 birds during the spring ^
migration counts and between 363 and 'nebird watching blind at the Pintail Marsh in Show Low,
478 birds during the fall migration counts. Arizona, provides educational opportunities for school children.
Detailed bird population data were col-
lected from natural treatment wetlands at
Houghton Lake, Michigan (Site No. 709),
and Vereen, South Carolina (Site No. 22).
Total number of bird species recorded at the
Houghton Lake site (based on three tran-
sects combined) were between 34 and 45
from 1978-89 and have declined somewhat
more recently. Total number of bird species
at Vereen varied from 35 to 45 during the
first 5 years of operation, compared with
41 species during the baseline study.
Avian botulism is a paralytic disease of
birds caused by ingesting a toxin produced
by Clostridium botulinum. Insufficient evi-
dence is currently available to identify the
specific causes of outbreaks of avian botu-
lism. Avian botulism is a problem in many
wildlife refuges and is known to occur in
Western wetlands that receive agricultural
return flows and drain waters. Botulism has
also been observed to occur in deep water
wetlands and rivers with high oxygen. Al-
though wastewater discharges and treatment
wetlands have been implicated with the
propagation of this disease (Friend, 1985),
specific documented case histories are rare.
Avian cholera is a highly infectious disease
caused by the bacterium Pasteurella multo-
cida (Friend, 1987). Death can occur in as
little as 6 to 12 hours following exposure.
Migratory waterfowl concentrated in wet-
lands are particularly susceptible to this in-
fection, and many other wetland-dependent
bird species can also be infected with the
disease. Avian cholera has been reported at
one treatment wetland, the Hayward Marsh
(Site No. 51) on the east shore of San Fran-
cisco Bay, south of Oakland, California.
Annual episodes of avian cholera have been
noted at this site for the past 6 years. In-
fected birds are collected, counted, and dis-
posed of to reduce spread of the disease.
The average number of infected waterfowl
collected during the 6-year period was
127 per year (15 to 340 birds per year).
This wetland supports very high waterfowl
populations during the fall months, with
peak numbers above 30,000 birds per day.
Also, avian cholera is encountered in nearly
all wetlands in and around San Francisco
Bay. For these reasons, there appears to be
no relationship between the avian cholera
observed at this location and the source or
quality of the water treated at this system.
A parasite that is known to infect wading
birds feeding on small fish in Florida wet-
lands is Eustrongyloides ignotus (Spalding,
1990). Only a few studies of the occurrence
of eustrongylidosis in wetland wading birds
17
-------
at treatment wetlands have been conducted
(Frederick and McGehee, 1994). The most
comprehensive study to date was at the
Everglades Nutrient Removal project (Site
No. 92) in south Florida. Of 12,000 indi-
vidual fish and 19 species sampled and
analyzed during this study, none were in-
fected with the nematode responsible for
eustrongylidosis (South Florida Water Man-
agement District [SFWMD], 1997).
Mammals
Forty mammal species are recorded in
NADB v. 2.0. A total of 22 species are re-
ported from 6 constructed treatment wetland
sites and 27 species from 4 natural treat-
ment wetland sites. Quantitative data on
mammal populations are limited in the data-
base to small mammal surveys at the con-
structed treatment wetland in Iron Bridge,
Florida (Site No. 92) (from the downstream
Seminole Ranch wetlands that receive the
discharge from Iron Bridge) and at the
natural treatment marsh in Houghton Lake,
Michigan (Site No. 209).
Small mammal densities at Iron Bridge
ranged from 2.0 to 37 individuals per hec-
tare with from 1 to 3 species collected on
each sample date. Small mammal densities
at Houghton Lake ranged from 140 to
213 individuals per hectare with 2 to
7 species per transect in 1979, and 7 to
213 individuals per hectare with 1 to
3 species per transect in 1989. Small mam-
mal monitoring was conducted on three
transects at Houghton Lake from 1979-89.
These transects were located at 15 meters
(m), 250 m, and 500 m downstream of the
treated effluent distribution line. Higher
small mammal densities and diversities
have generally been obtained closer to the
distribution pipe in an area of leatherleaf
and bog birch mixed with cattails.
Summary and Data Requirements
Qualitative and quantitative studies of
animals inhabiting constructed and natural
treatment wetlands have revealed that these
ecosystems provide attractive and produc-
tive habitats. All trophic levels are repre-
sented, from microscopic invertebrates to
macroinvertebrates, fish, herptiles, birds,
and mammals. Numbers of species appear
to be generally similar between constructed
and natural wetland sites. However, insuffi-
cient quantitative faunal data currently exist
to correlate population diversity or density
with treatment wetland design criteria such
as pretreatment water quality, mass loading
for key pollutants and nutrients, water
depth, vegetation types, etc. Essentially, all
conclusions concerning relationships be-
tween wildlife populations and wetland
design must be based on other studies or are
currently anecdotal. This lack of informa-
tion emphasizes the need for well-designed,
quantitative studies of wildlife populations
conducted in the context of controlled
treatment wetland research projects.
Toxic Metals and Trace
Organics in Treatment
Wetlands
Introduction
A variety of data for metals and trace
organic compounds have been collected
from 26 wetland treatment wetland sites.
Data entered into the NADB v. 2.0 were
grouped by the sample matrix: surface
water, sediment, or tissue. Tissue samples
were further divided into vegetation and
wildlife groups. Many data records for
metal and trace organic compound concen-
trations are below detection limits (BDL) in
the raw data in the NADB v. 2.0.
Metals
Available data for 25 metals and related
elements measured in surface waters,
18
-------
Comparison of treatment trace metal concentrations to chronic ambient -water quality criteria. Mean treatment
wetland concentrations are typically close to or less than water quality criteria; however, some means and most
maximum reported values are above chronic criteria.
Chronic Ambient
Wetland Effluent Outflow Water Concentration (ug/L)
Metal
Arsenic
Cadmium
Chromium (III)
Copper
Lead
Mercury
Nickel
Selenium
Silver
Zinc
Water Quality
Criteria (ug/L)a
190
1.0 h
180 h
11 h
2.5 h
1.3
160 h
5.0
100 h
Constructed Treatment
Mean
5.1
0.5
4.0
7.4
5.4
0.53
14.1
1.4
0.56
22
Max
25
5.0
30
90
40
4.9
210
12
5.0
320
% BDL
14
69
41
32
51
62
31
69
75
35
Natural Treatment Wetlands
Mean
N.D.
1.2
17
3.0
3.2
0.24
9.3
N.D.
3.9
10
Max
N.D.
5.0
69
15
15
1.0
25
N.D.
15
39
% BDL
N.D.
80
50
31
52
86
72
N.D.
70
42
a U.S. EPA1986a, 1986b, 1987
h = hardness-dependent, assumes 100 mg/l as CaCOS
N.D. = not determined
ug/L = micrograms per Iliter
sediments, and biological tissues from treat-
ment wetlands are summarized in the NADB
v. 2.0. These data confirm numerous pub-
lished reports that treatment wetlands reduce
surface water concentrations of metals. They
also provide a basis for comparing treatment
wetland sediment and tissue metals data to
published criteria that are considered to be
protective of environmental health. Most cri-
teria are based on laboratory tests on highly
sensitive species. Comparisons of treatment
wetland trace metal concentrations to pub-
lished criteria should be cautious due to the
general lack of,research that demonstrates
that criteria levels actually create effects in
wetland environments.
Trace Organics
Data for more than 120 trace organic com-
pounds are reported for treatment wetland
surface water, sediments, and tissues. Detect-
able levels for some of these trace organics
were found in treatment wetland surface
waters, sediments, and biological tissues. A
total of 29 trace organic compounds were
detected (out of 121 analyzed for) in con-
structed treatment wetland sediments.
Summary
Wetlands and other aquatic ecosystems can
reduce concentrations of metals and trace
organics through their complex array of
physical, chemical, and biological pro-
cesses. The efficiency of these pollutant
removal processes is of interest as treatment
wetlands are being designed for a greater
variety of wastewaters with a wide range of
concentrations of these trace elements and
compounds. On the other hand, sequestra-
tion of trace metals and organics in treat-
ment wetlands creates a potential for
detrimental biological effects due to the
chemically stable forms of these compounds
and their biological toxicity. While some
trace organics are lost from the wetland
environment through biological degradation
or atmospheric volatilization, other organics
and most metals tend to accumulate in sedi-
ments and in biological tissues.
An important issue needing to be scrut-
inized is the extent to which these, poten-
tially toxic chemicals bioaccumulate and
whether they are present in amounts that are
19
-------
toxic to the biota that normally inhabit these
wetland environments. The data sum-
marized in the NADB v. 2.0 provide a basis
from which to begin finding answers to
these questions. However, additional data
from controlled, realistic-scale treatment
wetland research will need to be collected
and analyzed to fully evaluate treatment
performance and the potential for detri-
mental effects from each metal or organic
compound of interest.
Effects of Treatment Wetlands
on Whole-Effluent Toxicity
Introduction
The Clean Water Act requires that dis-
charges to waters of the United States be
"free of toxic substances hi toxic amounts."
While it is widely recognized that low
levels of potentially toxic substances exist
in nearly all effluents and in most natural
surface waters, no significant detrimental
effects from those substances is expected
unless concentrations exceed critical levels.
The definitions of those critical levels are
based on a variety of methods that seek to
quantify effects to sensitive groups of
aquatic organisms. When practical, specific
water quality criteria are established by
The ffayfield Site demonstration wetland at Tres Rios west of Phoenix,
Arizona, includes two cells with variable numbers of deep -water zones to
lest their effect on hydraulic efficiency and wildlife habitat.
20
U.S. EPA to define acceptable maximum
levels for specific toxic chemicals, espe-
cially heavy metals and trace organics
(U.S. EPA, 1986). Permit criteria reflect
these critical levels when it is possible to
"identify specific chemicals in an"efflueht"
that may occur in toxic amounts.
The concept of "whole-effluent" toxicity
standards has been developed to regulate
releases of complex effluents that may con-
tain from several to dozens of potentially
toxic chemicals. Standardized toxicity tests
have been developed by U.S. EPA to define
the concept of whole-effluent toxicity test-
ing (U.S. EPA, 1989). The freshwater test
organisms most frequently used are the
fathead minnow (Pimephales promelas) and
water flea (Ceriodaphnia dubid). These
tests look for "acute" or "chronic" toxicity.
Acute toxicity is defined as conditions that
lead to the relatively rapid death of the test
organism. Chronic toxicity is a measure of
sublethal effects that ultimately result in a
decrease of the organism's population size
through impaired behavior or reproduction.
End points typically vary from 24 to
96 hours for acute tests and are typically
7 days for chronic tests. Both acute and
chronic whole-effluent toxicity test data are
included in the NADB v. 2.0.
Two primary issues are related to whole-
effluent toxicity tests and treatment wet-
lands. The first issue is determining how
effective wetlands are as a water quality
treatment system in reducing concentrations
or bioavailability of toxins and, thereby,
reducing whole-effluent toxicity of a waste-
water effluent before it is discharged to a
receiving water environment. This issue can
be characterized as the effect of the wetland
on the toxin(s). To examine this first issue,
whole-effluent toxicity input/output data
collected from wetlands treating waste-
waters are summarized in the NADB v. 2.0.
-------
The second issue deals with the potential
effects of effluent toxicity to organisms with-
in the treatment wetland. This issue can be
characterized as the effect of the toxin(s) on
the wetland. The relevancy of acute and
chronic whole-effluent toxicity tests to wet-
land environments has not been examined.
These tests are simplistic in that they focus
all attention on only one or two animal
species that may or may not have sensitivity
to toxins similar to the fauna that normally
occur in wetlands. Wetland environments are
typically dominated by plant and animal
species that are hardier and less sensitive to
pollutants than more sensitive species that
may occur in other surface waters. Quanti-
tative data of direct or indirect toxic effects
to wildlife in treatment wetlands are gen-
erally lacking.
Acute Toxicity
Acute toxicity test results were available
from four treatment wetlands. No significant
mortality was observed at three of these sites
receiving municipal effluents. One site re-
ceiving an industrial effluent did record acute
toxicity to minnows and waterfleas (15- to
16-percent mortality in 100-percent effluent)
in treatment wetland effluent samples.
Chronic Toxicity
Chronic toxicity results were available from
10 treatment wetland systems. Nine of these
systems are constructed and one is a natural
treatment wetland. Some chronic toxicity
was identified at several sites, but chronic
toxicity effects are consistently reduced by
passage through treatment wetlands with
surface discharges.
Summary
Acute and chronic whole-effluent toxicity
test results are available at a limited number
of treatment wetland sites in North America.
-With-a-fewexceptions,- any-acute or-chronic
toxicity that may be present in wetland in-
fluent is reduced or completely eliminated
after the wastewater passes through the wet-
land. One example exists in an evaporative
treatment wetland where toxicity to fresh-
water test organisms increases with distance
from the point of wastewater input due to
increasing total dissolved solids.
Whole-effluent toxicity tests do not distin-
guish the source of toxicity; therefore,
mechanisms for toxicity reduction in
wetlands are likely to vary greatly and to
depend on the form of the toxicant. A vari-
ety of metals and trace organics may cause
acute or chronic toxicity in wastewater
effluents. Additional study with treatment
wetlands is necessary to understand the
effects of toxicants on the wetland biota as
well as the effects of the wetland on the
toxicant.
Human Use of Treatment
primary goal of most treatment
wetlands is water quality improvement.
A voooden tower
provides a
panoramic view of
the Boggy Gut
Wetland'oWHilton"
Head Island, South
Carolina.
21
-------
Increasingly, however, treatment wetlands
have multiple purposes; and it cannot al-
ways be assumed that their water treatment
goal is more important than their other
roles, such as creating wildlife habitat or
human recreation areas. The majority of this
Executive Summary focuses on the habitat
functions of treatment wetlands. This proj-
ect also summarized what is known about
their human uses other than water quality
improvement.
Recognized human uses of treatment wet-
lands in addition to water purification can
be lumped into five general categories:
4 Nature study
4 Exercise activities
4 Recreational harvest
4 Education
4 Commercial harvest
Activities in Treatment Wetlands
Summaries of human use data exist for only
a few treatment wetland systems.
The Arcata, California (Site No. 25), con-
structed wetland is used by an estimated
100,000 visitors per year (Benjamin, 1993).
This level of activity is sustained because
the system is located in a progressive,
coastal California community near a trail
system and park-like setting. Data from
Arcata summarized in the NADB v. 2.0
indicate that from 27,000 to 64,000 human
use-days per year (HUD/y) are devoted to
general picnicking and relaxing. These data
may also be expressed on a unit area basis
as a total of about 1,600 HUD per hectare
per year (HUD/ha/y) for the entire Arcata
Marsh and Wildlife Sanctuary. At the Show
Low, Arizona (Site No. 76), constructed
treatment wetland, human use data are
lumped for all categories and averaged
about 370 HUD/yr or about 7 HUD/ha/yr.
The Iron Bridge, Florida (Site No. 13),
constructed wetland has an overall
estimated human use of about 4,800 HUD/y
or about 10 HUD/ha/y.
Nature Study
Nature study includes a variety of activities
that may be associated with treatment
wetland projects:
4 Bird study
4 Plant observation and identification
4 Observation and identification of other
wildlife groups
4 Plant and wildlife photography
4 Plant and wildlife art
Few data are available that specifically
describe any of these activities. Arcata,
California, has reported data indicating
about 10,000 HUD/yr or 165 HUD/ha/yr
for bird watching. Photography and art
22
Bird counts have shown that constructed treatment
wetlands have bird diversity and population numbers
as high or higher than many natural -wetlands.
-------
account for about 360 to 900 HUD/yr at
Arcata. Anecdotal information is available
that indicates that bird watching groups
regularly use treatment wetlands at West
Jackson County, Mississippi (Site No. 18);
Hillsboro, Oregon; Show Low, Arizona
(Site No. 76); Pinetop-Lakeside, Arizona;
Lakeland, Florida (Site No. 1); and Iron
Bridge, Florida (Site No. 13). Some of these
sites are visited by organized groups on a
regular basis (once a week or month), while
others are visited by individuals or groups
on a less regular schedule.
Exercise Activities
When treatment wetlands are open to the
public, they are frequently used for
activities that provide exercise. Forms of
exercise known to occur in treatment
wetlands include hiking, jogging, and
off-road bicycling.
Treatment wetland sites that are open to the
general public for these activities include
Show Low, Arizona; Pinetop-Lakeside,
Arizona; Tres Rios, Arizona; Arcata, Cali-
fornia; Sea Pines, South Carolina; Iron
Bridge, Florida; Cannon Beach, Oregon
(Site No. 204); Hillsboro, Oregon; and
Mountain View, California (Site No. 312).
Hiking and jogging at the Arcata, Cali-
fornia, constructed wetland is estimated as
about 18,000 HUD/yr. One specific compo-
nent of this use that was identified includes
about 900 HUD/yr just for walks led by the
Redwood Region Audubon Society.
No other quantitative data specifically re-
cording exercise activities in treatment wet-
lands were available for this review.
Recreational Harvest
A small number of treatment wetlands are
open to the public or to private individuals
for hunting and/or fishing.
The city of Arcata, California, has made
its Arcata Marsh a community affair.
A borrow pit at the Arcata Marsh and
Wildlife Sanctuary in California is open for
fishing, but use is reported to be light and
seasonal.
At Incline Village, Nevada (Site No. 310),
duck blinds are available on a lottery basis.
Typical hunter use days are about
877 HUD/yr or 5.6 HUD/ha/yr. About
817 ducks and 60 geese are harvested per
year at this constructed wetland.
The Iron Bridge, Florida (Site No. 13), con-
structed wetland is closed to the public
from September through March of each
year and is available to former land owners
for waterfowl hunting and fishing during
this period. The Houghton Lake, Michigan,
natural treatment wetland (Site No. 209);
the Show Low, Arizona (Site No. 76),
constructed wetland; and the area down-
stream of the Columbia, Missouri, con-
structed wetland are open to hunters as
state-controlled wildlife management areas.
About 836 HUD/yr or 1.6 HUD/ha/yr are
available for duck hunting at the Columbia,
Missouri, site.
Education
Treatment wetlands have been used for a
variety of educational opportunities. Some
23
-------
sites are open for controlled access of grade
school and high school students and for
various college classes and individual
undergraduate and graduate research. The
only two sites that were quantified are
Arcata, California, with an estimated
1,500 HUD/yr and Vereen, South Carolina,
with an estimated 234 educational and
research HUD/yr.
Commercial Harvest
The potential to use treatment wetlands for
commercial production of food and fiber
has been discussed (Wengrzynek and
Terrell, 1990; Knight, 1992; Kadlec and
Knight, 1996). Types of potential
commercial uses include:
4 Plant harvesting for food (such as water
chestnuts) or fiber (such as common
reed, pulp wood, saw timber)
4 Trapping of mammals for furs (nutria,
muskrat, beaver)
+ Aquaculture (baitfish, food fish, crayfish,
frog legs, etc.)
No data concerning any of these uses were
obtained for this project.
Permitting-r-elated work at the Pintail Marsh in Show Low, Arizona
(Site No. 76), included an assessment of the net ecological benefits of
these effluent-dependent waters.
24
Miscellaneous Activities
Treatment wetlands may provide human-use
benefits other than those described above. It
is not possible at this time to anticipate all
of the possible uses that will be derived
from these green machines. Types of
miscellaneous activities that have been
observed include:
* School projects to name constructed
wetlands
4 Community service outings to help plant
new constructed wetlands, clear trash,
and install bird and bat houses
4 Boy Scout projects to build public use
facilities
4 Citizen groups and government officials
meeting to review wastewater
management options
These activities are known to exist but have
been difficult to quantify.
Summary
Treatment wetlands often provide human
use benefits in addition to their primary role
for water quality treatment. These uses vary
greatly and have been quantified in only a
few cases. Additional data on human use in
treatment wetlands are needed to determine
the significance of these activities and to
provide information to designers on how to
provide the best opportunities for cost-
effective use.
Treatment Wetland
Design for Wildlife
Habitat and Human Use
Introduction
The need for information related to the
potential effects of treatment wetlands on
natural biota and humans has been recog-
nized for years (Godfrey et al, 1985;
-------
Feierabend, 1989). The ETI Treatment Wet-
land Habitat Project is the first attempt to
provide a comprehensive summary of our
knowledge concerning the relationship be-
tween treatment wetlands and their inter-
action with wildlife and human use. While
this summary indicates significant areas of
incomplete understanding, it also provides a
clearer view of those areas where conclu-
sions are warranted.
The information in this Executive Summary
and the companion report Indicates that
treatment wetlands typically have the fol-
lowing properties:
4 Their biological structure is substantial
and is dominated by relatively diverse
assemblages of wetland plant species,
typically including a few dominants and
many less common species that have
specific adaptations to grow in saturated
soils.
4 All major animal groups and trophic
levels that occur in natural wetlands are
represented in treatment wetlands;
population size and diversity in treatment
wetlands are generally as high or higher
than in other wetlands; no documented
occurrences of detrimental effects to
wildlife caused by the pollutant-cleansing
function of treatment wetlands were
noted.
* Contaminant data from treatment
wetlands for heavy metals and trace
organics are available for sediments and
biological tissues; treatment wetlands are
effective at reducing concentrations of
these pollutants; these data do not
generally indicate a threat to flora and
fauna based on the existing range of
contaminant loadings.
* Treatment wetlands are generally
effective at reducing levels of whole-
effluent toxicity.
4 Humans are using treatment wetlands for
a variety of purposes in addition to water
quality enhancement.
As data concerning each of these items
continue to become more available, the
next step is to apply this information to the
design and operation of new and existing
treatment wetlands. Brief discussions of
important areas for additional research and
how resulting knowledge might be applied
in the future are provided below. New
projects that have benefited from this
expanding information base have been
designed and implemented during the
lifetime of the ETI Treatment Wetland
Project. Examples of these new systems
include municipal effluent treatment
wetland projects at Beaufort, South
Carolina (Great Swamp Natural Effluent
Management System); Tucson, Arizona
(Sweetwater Wetlands); and Palm Beach
County, Florida (Wakodahatcb.ee Wetlands).
Water Quality Considerations
The effects of wetlands on water quality
have been described in detail elsewhere
(e.g., Kadlec and Knight, 1996; U.S. EPA,
1999). The ETI Treatment Wetland Habitat
Project is intended to provide information
to researchers who may wish to examine the
flip side of this question—namely, the effect
of the water quality on the wetland
environment.
Contaminants in wastewaters are known to
affect the wetland environment. These
effects are highly variable depending on the
specific constituents and the biological
components of the wetland in question.
Research efforts should be designed to cor-
relate these water quality conditions with
treatment wetland environmental condi-
tions. The most basic comparisons have not
been made between treatment wetlands with
varying dissolved oxygen and nutrient con-
ditions and their ability to support diverse
25
-------
Summary of design considerations for treatment -wetland habitat and public use benefits.
Design Criteria Explanation
Water Quality Considerations
Pre-treat toxic trace metals and organics
It is important to protect those wildlife species that range
outside the boundaries of the treatment plant.
Pre-treat excessive loads of mineral and organic
sediments
High sediment loads can suffocate wetland emergent
plant roots.
Pre-treat excessive organic and ammonia nitrogen
concentrations
High loadings of oxygen-demanding substances will
cause nuisance conditions in treatment wetlands,
including poor plant growth.
Wildlife Habitat Considerations
Design flexibility to control water levels
Water level control is the principal tool available to
control plant growth and water quality improvement.
Incorporate deep-water zones without creating
hydraulic short circuits
Deep water zones serve multiple purposes, including
improved hydraulic mixing and residence time, a sump
for solids storage, and perrenial habitat for fish and
waterfowl.
Utilize a diversity of plant species
Polyculture will provide greater habitat diversity and
greater resistence to pests and operational upsets.
Utilize plant species with known benefits to wildlife
species
Each plant species provides differing benefits to different
wildlife species/groups.
Incorporate vertical structure by planting aquatic,
emergent, shrub, and canopy strata, and by installing
snags and nesting platforms
Structural diversity equates to habitat variety for feeding,
roosting, and nesting wildlife.
Incorporate horizontal structure by providing littoral
shelves, islands, and the use of irregular shorelines
Plant diversity is promoted by varying water depths,
islands provide a refuge for birds and other wildlife, and
irregular shorelines provide visual cover and greater
ecotone length.
Public Use Considerations
Provide parking and safe access to wetlands
Humans will be attracted if they have access and feel
safe.
Provide boardwalks and observation points
Boardwalks allow the public to get a "feel" for being in
the wetland environment.
Incorporate interpretive displays
The public is eager to learn more about the structure
and function of wetlands.
Collect public comment and incorporate in design/
operation modifications
The public will provide useful suggestions for
improvement.
Publicize the wetlands
The public can be an ally during permitting and funding
for treatment wetlands.
Inlist volunteer participation
Providing the public with a sense of ownership will help
enlist support.
Establish accessible monitoring points
Treatment wetlands provide excellent classrooms for
environmental study.
Provide blinds for wildlife study
Observing wildlife without disturbing it will optimize both
habitat and public uses.
Maintain adequate monitoring records
The public has a right to know about any hazards or
benefits created by a treatment wetland.
26
-------
plant and animal populations. Although pH
requirements for some individual plant and
animal species are known, there are no
studies of the effect of varying pH in treat-
ment wetlands. Although the toxicity of
many trace metals and organics are known
in laboratory studies with one or a few plant
or animal species, there is very little infor-
mation on the ecosystem-level effects of
these substances in treatment wetlands. The
information collected for this ETI Treatment
Wetland Habitat Project provides only a
starting point for the studies needed to
develop empirically based treatment/habitat
wetland design criteria.
Biological Considerations
During the review of new and existing dis-
charge permits to treatment wetlands, envi-
ronmental agency staff are frequently faced
with the difficulty of assessing the potential
for harmful environmental effects. The
potential receptors of most interest are typi-
cally the vertebrate inhabitants of the wet-
lands including fish, amphibians, reptiles,
birds, and, to a lesser extent, mammals.
These organisms tend to be more visible to
people than the invertebrates, and concern
for their fate is highest in the public's pri-
orities. While it is recognized that the inver-
tebrates are also of importance, their protec-
tion is generally justified based on their
place in the food chain supporting the
vertebrate forms.
While the use of wetlands to improve the
quality of wastewaters is considered an
important goal, it is also important to
balance the benefits of meeting that goal
with the avoidance of harm to those organ-
isms that will ultimately reside in the living
treatment system.
The information gathered for this report in-
dicates that biological changes can occur in
response to discharges of treated effluents.
These changes cover the spectrum from
obvious to subtle. Many of the changes that
have been noted favor one group of species
over another. The most common changes
result in an increase of wetland structure
and function at an ecosystem level. Assign-
ing value judgments to these types of
changes becomes a matter of perspective.
There is currently no evidence that treated
wastewater effluents cause increased risks
for vertebrates in treatment wetlands. This
lack of evidence does not prove that there
are no effects, but it indicates that most
treatment wetland projects can be permitted
without special requirements other than
reasonable caution. Greater caution should
be exercised when project wastewaters are
known or suspected to contain unusually
elevated concentrations of heavy metals,
trace organics, un-ionized ammonia, or
other chemicals that are likely to be acutely
or chronically toxic to aquatic and wetland
biota. These potentially toxic chemicals are
of special interest only when they are at
concentrations above the range typical of
Alligators are a
common predator in
natural constructed
treatment wetlands
throughout the
Southeastern United
States.
27
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The Cobble Site
Demonstration
Treatment
Wetland for the
city of Phoenix
tests the
feasibility of
recreating habitat
in the dry channel
of the Salt River.
28
normal wastewaters from the same general
source. This greater level of caution during
project design and review is most relevant
to those wastewaters, leachates, and storm-
waters that have received minimum levels
ofpretreatment.
Human Use
Very little information is available about
how to best integrate human use with treat-
ment wetlands. Benjamin (1993) presents a
highly useful summary of the issues related
to public perception and use of the most-
visited treatment wetland in the United
States, the Arcata Marsh and Wildlife
Sanctuary in California. That study con-
cluded that the Arcata Marsh is a great suc-
cess in its role as a community open space
and as a recreational, ecological, and educa-
tional resource. Interviews identified birds
and wildlife viewing as the most popular
public uses of the marsh. The second most
common response to questions about the
benefits of the marsh focused on its
aesthetic qualities, including scenery,
beauty, and open space. The most common
response to the survey question concerning
what the public disliked about the Arcata
Marsh was "nothing." These obvious bene-
fits are being accomplished even as the
Arcata Marsh meets its primary goal of
water quality protection.
Anecdotal information indicates that similar
responses might be obtained at several other
treatment wetland sites open to the public.
Studies similar to the one conducted by
Benjamin (1993) should be conducted at a
number of treatment wetlands that are open
to the public to develop a wider understand-
ing of how humans interact with wetlands.
Summary
The ETI Treatment Wetland Habitat Project
demonstrates that both natural and con-
structed treatment wetlands have substantial
plant communities and wildlife populations.
The concern that treatment wetlands are
botanical monocultures is not supported by
the data. Diverse and abundant populations
of wildlife use the variety of niches pro-
vided by the complex plant communities
that develop in many treatment wetlands.
This project has documented the presence
of potentially harmful substances in the
water, sediments, and biological tissues of
treatment wetlands. While it is highly likely
that some or all of these substances at high
concentrations could create harmful con-
ditions for the biota attracted to treatment
wetlands, contaminant concentrations are
generally below published action levels, and
there is apparently no documentation that
harm has occurred in any wetland inten-
tionally designed for water quality improve-
ment. While this lack of evidence does not
prove that harm does not occur somewhere
in a treatment wetland, current evidence
-------
indicates that treatment wetlands support
complex ecosystems that are as productive
as, or more productive than, unaltered
natural wetlands.
This project represents a first step at col-
lecting and summarizing the information on
habitat and wildlife use of treatment wet-
lands. The number of new treatment wet-
land projects gathering and reporting these
types of data is increasing yearly. While
substantial data about the diversity of plants
and animals inhabiting treatment wetlands
are available, it is hoped that these new and
ongoing studies will shed greater light on
the ecological functions of these systems
and their full potential for environmental
benefit or harm.
References
Bastian, R.K. and D.A. Hammer. 1993. The
Use of Constructed Wetlands for Waste-
water Treatment and Recycling. Chapter 5,
pp. 59-68 in G.A. Moshiri (ed.), Con-
structed Wetlands for Water Quality Im-
provement. Lewis Publishers, Boca Raton,
Florida.
Bastian, R.K., RE. Shanaghan, and
B.R Thompson. 1989. Use of Wetlands for
Municipal Wastewater Treatment and Dis-
posal-Regulatory Issues and EPA Policies.
Chapter 22, pp. 265-278. In D.A. Hammer
(ed.), Constructed Wetlands for Wastewater
Treatment: Municipal, Industrial, and
Agricultural. Lewis Publishers, Chelsea,
Michigan.
Benjamin, T.S. 1993. Alternative Waste-
water Treatment Methods as Community
Resources: The Arcata Marsh and Beyond.
Master of Landscape Architecture Thesis,
University of California at Berkeley.
CH2MHILL, 1997. Treatment Wetland
Habitat and Wildlife Use Assessment
Project. Prepared for the U.S. Environ-
mental Protection Agency, U.S. Bureau of
Reclamation, and the city of Phoenix with
funding from the Environmental
Technology Initiative Program.
CH2M HILL and Payne Engineering. 1997.
Constructed Wetlands for Livestock
Wastewater Management. Literature
Review, Database, and Research Synthesis.
Report prepared for the Gulf of Mexico
Program, Nutrient Enrichment Committee,
Stennis Space Center, Mississippi.
Frederick, P.C. and S.M. McGehee. 1994.
"Wading Bird Use of Wastewater Treatment
Wetlands in Central Florida, USA."
Colonial Waterbirds 17(l):50-59.
Freierabend, J.S. 1989. Wetlands: The
Lifeblood of Wildlife Chapter 7, pp. 107-
118. In D.A. Hammer (ed.), Constructed
Wetlands for Wastewater Treatment:
Municipal, Industrial, and Agricultural.
Chelsea, Michigan: Lewis Publishers.
1989.
Many constructed treatment -wetland designs include
diverse plantings of native -wetland species to provide
-wildlife habitat as well as project aesthetics.
29
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Friend, M. 1987. (ed.) Field Guide to
Wildlife Diseases. Volume 1. General Field
Procedures and Diseases of Migratory
birds. U.S. Department of the Interior, Fish
and Wildlife Service. National Wildlife
Health Center, Madison, Wisconsin.
Friend, M. 1985. Wildlife Health Implica-
tions of Sewage Disposal in Wetlands.
Chapter 17, pp. 262-269 in: P.J. Godfrey,
E.R. Kaynor, S. Pelczanski, and J. Ben-
forado (eds.). Ecological Considerations in
Wetlands Treatment of Municipal Waste-
waters. Van Nostrand Reinhold, New York.
Godfrey, P.J., E.R. Kaynor, S. Pelczarski,
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