United States
Environmental Protection
Agency
Environmental Research
Laboratory
Corvallis, OR 97333
EPA/600/R-93/117
July 1993
Research and Development
V> EPA HABITAT QUALITY ASSESSMENT OF TWO WETLAND
TREATMENT SYSTEMS IN THE ARID WEST - PILOT STUDY
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HABITAT QUALITY ASSESSMENT OF TWO WETLAND TREATMENT SYSTEMS
IN THE ARID WEST - A PILOT STUDY
Lynne S. McAllister
ManTech Environmental Technology, Inc.
U.S. EPA, Environmental Research Laboratory
Corvallis, OR 97333
Project Officer
Mary E. Kentula
U.S. Environmental Protection Agency
U.S. Environmental Protection Agency
Environmental Research Laboratory
200 SW 35th Street
Corvallis, OR 97333
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S 1
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DISCLAIMER
The information in this document has been funded wholly or in part
by the United States Environmental Protection Agency under contract
number 68-C8-0006 to ManTech Environmental Technology, Inc., and
68-C8-0056 to AScI Corporation, Duluth, MN. It has been subjected
to the Agency's peer and administrative review, and it has been
approved for publication as an EPA document. Mention of trade
names or commercial products does not constitute endorsement or
recommendation for use.
This document should be cited as:
McAllister, L.S. 1993. Habitat quality assessment of two wetland
treatment systems in the arid West - A pilot study. EPA/600/R-
93/117. U.S. Environmental Protection Agency, Environmental
Research Laboratory, Corvallis, OR.
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CONTENTS
DISCLAIMER ......... ii
TABLES V
FIGURES Vii
ACKNOWLEDGEMENTS viii
EXECUTIVE SUMMARY x
INTRODUCTION 1
Role of EPA in WTS Operations 1
Assessing Wetland Function and Ecological Condition . . 2
Use of Indicators ... 2
Use of the Wetland Evaluation Technique 3
Factors Affecting Habitat Quality . 4
Research Objectives . 4
METHODS 6
Pilot Study Overview 6
Site Selection 6
Habitat Quality Assessment ...... 7
Measurement of Indicators 8
Evaluation of Ancillary Values Using WET ... 8
Western Study . 8
Site Descriptions 10
Field and Laboratory Methods 12
Site Characterization 12
Vegetation Sampling 12
Invertebrate Sampling and Identification ... 14
Whole Effluent Toxicity Testing ....... 16
Bird Surveys . 17
Evaluation of Ancillary Values 18
Site Morphology ........ ..... 19
Acquisition and Use of Existing Data on Water
Quality . 19
Data Analysis 20
Comparison Data from the Literature 23
Quality Assurance 24
RESULTS AND DISCUSSION 27
Vegetation 27
Invertebrates 35
Whole Effluent Toxicity Tests ........ 43
Bird Use 46
Ground Survey Results 46
Aerial Surveys Results - Incline Village Site ... 54
Bird Indicator Discussion 54
Evaluation of Ancillary Values ............. 57
Site Morphology 60
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Water Quality ..........
CONCLUSIONS AND RECOMMENDATIONS ....
LITERATURE CITED .
APPENDIX A. Site maps and sampling points
Site contacts and local experts consulted
APPENDIX B.
APPENDIX C.
APPENDIX D.
APPENDIX E.
Invertebrate biologists and identification
keys used
Water chemistry of replicates used for whole
effluent toxicity tests . .
Detailed bird survey data
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72
78
87
91
93
95
98
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TABLES
Table 1. Names, locations, construction dates, and sizes of
WTS sampled in the pilot study 7
Table 2. Pilot study field sampling schedule 7
Table 3. Indicators of wetland ecological condition measured
during the 1991 pilot study 9
Table 4. Water quality data available from each site .... 21
Table 5. Percent of plant species and average percent cover
of each vegetation structural layer at the Show Low
and Incline Village sites, 1991 28
Table 6. Frequency of occurrence, average percent cover per
square meter ± one standard deviation, and
dominance (indicated by *) for each plant species
sampled at the Show Low and Incline Village sites,
1991 30
Table 7. Aquatic invertebrate taxa and their relative
abundances at the Show Low and Incline Village
sites, 1991 36
Table 8. Number of invertebrates collected per person-hour
in each cell at the Show Low and Incline Village
sites . 40
Table 9. Number of invertebrates collected per person-hour
in each habitat type at the Show Low and Incline
Village sites . 40
Table 10. Relative abundances of invertebrate functional
groups. Show Low, AZ, and Incline Village, NV,
1991 o 42
Table 11. Reproduction and survival of Ceriodaphnia dubia . . 45
Table 12. Measurements on water samples performed by ERL-
Duluth ..... ..... 45
Table 13. Bird density and species richness of surveyed
species from ground surveys conducted at the Show
Low and Incline Village sites, 1991 47
Table 14. Bird species richness at the Washoe Lake Mitigation
Area, Nevada 50
Table 15. Mean species richness and density of birds reported
for wetlands of the Lower Colorado River and the
Salton Sea . 50
Table 16. Bird species richness and density (all bird species
included) in salt cedar and willow habitats at
Picacho Reservoir, AZ, 1982 51
Table 17. Waterfowl species richness from Apache-Sitgreaves
National Forest, Arizona, 1979-1980 51
Table 18. Bird species richness at Stillwater Wildlife
Management Area, and Lahontan Valley/Carson Lake,
Nevada, 1989-1991 .... 52
Table 19. Shorebird species richness in western Nevada
wetlands, 1991 53
Table 20. Waterfowl aerial survey summaries from the Incline
Village site (natural and WTS wetlands combined)
and non-WTS sites near the Incline Village site,
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surveyed in 1991 55
Table 21. WET ratings for the Show Low site 59
Table 22. Site morphology data accpiired from aerial
photographs of the Show Low site 61
Table 23. Shoreline length per wetland area and island area
for wetlands in the Apache-Sitgreaves National
Forest 64
Table 24. Summaries of water quality data at the Show Low and
Incline Village sites 66
Table 25. Surface water quality values in the Washoe Lake
Mitigation Area, 1990-1991 . 68
Table 26. Average pH and dissolved oxygen (DO) values from
wetland sites receiving irrigation drainage in
west-central Nevada, 1987-1989 69
Table 27. Average surface water quality values in and near
the Stillwater Wildlife Management Area and Carson
Lake, Nevada, 1986-87 70
Table 28. General relationship of data from the WTS studied
to the range of values reported for non-WTS in the
southwest United States 73
Table 29. Summary of indicator suitability 74
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FIGURES
Figure 1. Location and layout of Wetland treatment sites
studied in the arid West 11
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ACKNOWLEDGEMENTS
Numerous individuals contributed to the completion of this
research project, and, although I cannot list all of them, I
greatly appreciate their input. I am especially grateful to Jane
Schuler, who served as the other half of the field team and worked
many long, difficult days in the field to complete data collection
on schedule, and to JoEllen Honea, who made a substantial
contribution to the final document by conducting extensive
literature searches, developing the computer database, performing
all of the data analyses, and preparing tables for the report.
Richard Olson served as the project leader and provided
guidance throughout the project. Robert Bastian, Richard Olson,
and Robert Knight conceptualized the research approach and
initiated project planning. I am grateful to Paul Adamus, who
provided literature for supporting material, training in the
Wetland Evaluation Technique, and advice and guidance in the
planning and analysis stages of the project. Arthur Sherman
provided important documentation on sampling and quality assurance
procedures. Cindy Hagley, Debra Taylor, and Bill Sanville at the
EPA Environmental Research Laboratory in Duluth, MN, were very
helpful in planning and preparing for the field season.
Janelle Eskuri received water samples from the field and
conducted whole-effluent toxicity tests at EPA's Environmental
Research Lab in Duluth, MN. Janelle Eskuri, Teresa Norberg-King,
and Lara Anderson prepared documentation of whole-effluent test
methods and results, which were incorporated into the final report.
Nan Allen at the University of Minnesota-Duluth identified and
enumerated all of the invertebrates, prepared documentation, and
provided data for the final report. Ann Hershey conducted the data
quality checks for invertebrate quality assurance. Brenda Huntley
digitized cover types on aerial photographs and conducted all the
Geographic Information System work. Robert Gibson and Ted Ernst
wrote most of the data analysis programs and provided valuable
database and software operation support. Kristina Miller assisted
with word processing and editing and prepared Figure 1.
I thank the site managers - Mel Wilhelm and Terry Myers with
the U.S. Forest Service in Lakeside, AZ, and Don Ritchie at the
Incline Village General Improvement District in Incline Village, NV
- for permission to collect samples at their wastewater wetlands
and for their cooperation throughout the project. Ed Pollack at
Incline Village and Bruce Canavan with the city of Show Low
provided water quality data. I am grateful to Gail Durham, Mel
Wilhelm, and Terry Myers for the time they saved the field crew by
identifying collected plant specimens. Bird surveys were conducted
at the Incline Village site by Larry Neal, Hank St. Claire, and
Norm Sakey of the Nevada Department of Wildlife and at the Show Low
site by the White Mountain Audubon Society and White Mountain Land
Surveys. Surveyors provided data and supporting documentation for
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the final report. The time and effort spent by numerous
individuals who contributed data for use in the discussion are
greatly appreciated.
Harriet Hill, Robert Kadlec, Linden Piest, and James Moore
reviewed the manuscript. In addition, Kate Dwire provided a
quality assurance review, and Ann Heiirston and Amy Vickland
provided editorial reviews. All reviewers provided constructive
comments and suggestions for the final draft.
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EXECUTIVE SUMMARY
The use of wetland treatment systems (WTS), or constructed
wetlands, for treating municipal wastewater is increasing in the
United States, but little is known about the ability of these
systems to duplicate or sustain other wetland functions. This
pilot study was designed primarily to examine methods and the
usefulness of various wetland indicators for assessing the wildlife
habitat quality in six constructed WTS throughout the United
States. This report focuses on two of those sites, one located in
the Carson Valley, Nevada, and the other in the Apache-Sitgreaves
National Forest near Show Low, Arizona.
Vegetation, invertebrate, site morphology, water quality, and
bird data were collected in the field or compiled from existing
data sets. Various metrics were calculated as indicators of
wetland condition and were assessed for their usefulness in
characterizing wildlife habitat quality. Wildlife habitat quality
was assessed mainly with respect to birds. Indicator values were
compared with ranges of values of the same indicators from wetlands
in the arid West not used for wastewater treatment (non-WTS). Data
from non-WTS in the arid western United States were found in the
literature. Comparisons were meant to provide a -preliminary
examination of the wildlife habitat condition of the two WTS
studied by identifying any gross deviations from indicator values
from non-WTS. In addition, whole-effluent toxicity tests were
conducted on water samples representing high and low wetland
treatment at each WTS. As an alternative to indicator analysis,
the Wetland Evaluation Technique (WET) was tested at one of the
sites for its effectiveness and reliability in assessing various
wetland functions, including wildlife habitat, in WTS.
Most indicator values from WTS were within the range of values
from non-WTS. Bird species richness and density were above the
range of values from non-WTS. These preliminary results provide
evidence that the habitat condition of the two WTS studied is
comparable with that of non-WTS in the same region and that WTS are
especially attractive to birds. However, the results do not
indicate actual habitat value because little is known about the
habitat quality of non-WTS used in the comparisons.
Survival of Ceriodaphnia dubia and fathead minnows (Pimephales
promelas) was not significantly reduced in whole-effluent toxicity
tests. Reproduction of Ceriodaphnia dubia was significantly
reduced in water samples representing high wetland treatment at the
Incline Village site. It is likely that reduced reproduction was
caused by high conductivity and salinity at the water collection
site, but determining the precise cause and whether it is a risk to
other forms of wildlife would require further testing.
The WET ratings for the capability of the wetland tested to
support wildlife diversity and abundance were high for migrating
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and wintering wildlife and low for breeding wildlife. The rating
for aquatic diversity and abundance was also low. However, the
benefits to society of wildlife and aquatic diversity and abundance
at the wetland were rated high.
Results of this study provide evidence that the WTS studied
provide wildlife habitat as an ancillary benefit. Habitat at both
sites has been enhanced while maintaining effective water
treatment, which is evidence that the two interests are compatible.
A relatively dependable water supply helps ensure the development
and maintenance of wetland habitats in an arid environment. The
incorporation of varied and interspersed plant communities, as well
as the construction of islands has also enhanced wildlife habitat
quality.
For future assessment of wildlife habitat quality in WTS, it
is recommended that indicators from the following categories be
further tested and developed:
• vegetation
• invertebrates
• site morphology
Bird use is one potential indicator of the faunal component of a
WTS, but further consideration should be given to reduction of
sampling effort, collection of more specific metrics, and the
direct relevance of bird use to habitat quality. Invertebrate
sampling should be expanded to include benthic invertebrates. Use
of existing water nutrient data, whole-effluent toxicity tests, and
the WET analysis should not be continued or should have low
priority.
Water quality data is variable and difficult to interpret
consistently in terms of wildlife habitat. However, the collection
of a smaller set of water parameters during the field effort, such
as dissolved oxygen, turbidity, ammonia nitrogen, might provide
information on system stressors, which can be used to help explain
the status of other indicators.
Whole-effluent testing does not provide time-integrated
information or information about the effects of specific substances
in wastewater on wildlife. Because documentation of effects is a
long-term process and can become very expensive, effort should be
focused on contaminant testing of sediments and plant and animal
tissues only in wetlands, suspected to be at risk from contamination
or toxic inputs, such as wetlands receiving industrial discharges,
where contaminants have been found in the past, or where other data
collected indicate a potential problem requiring further
investigation.
For comparing wildlife habitat quality of WTS-to non-WTS,
future studies should include sampling at nearby reference sites
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(non-WTS) so that confounding factors are minimized and systematic
comparisons can be made between WTS and non-WTS. For assessing the
actual habitat quality of WTS, however, it is necessary to
establish some guidelines for rating habitat quality on a continuum
from high to low. Data reduction and assessment techniques,
possibly including development of habitat quality indices, should
be explored in future studies so that various indicators can be
aggregated and conclusions about overall habitat quality can be
derived from more rigorous analyses.
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INTRODUCTION
Freshwater, brackish, and saltwater wetlands can serve as
natural water purifiers for wastewater from point and nonpoint
sources. Declines in federal funds for municipal pollution control
and water pollution control mandates under the Clean Water Act for
municipal and industrial point source dischargers are leading to an
increase in the construction and use of wetlands for treating
wastewater. Municipal wetland treatment systems (hereafter
referred to as wetland treatment systems or WTS) are engineered
complexes of saturated substrates, emergent and submergent
vegetation, animal life, and water that simulate natural wetlands
for the primary purpose of wastewater treatment (Hammer and Bastian
1989). These systems receive partially treated wastewater and are
designed to reduce biochemical oxygen demand (BOD), nutrient and
metals concentrations, and levels of other pollutants in the water
(Kadlec and Kadlec 1979, Nixon and Lee 1986). WTS fall into two
general categories: 1) vegetated submerged-bed wetlands, in which
water moves through a nonsoil substrate in the system's bed and
makes contact with plant roots; and 2) free-water surface wetlands,
in which most of the water flow is above ground over saturated
soils (U.S. EPA 1988a, Reed et al. 1988).
This study focused on free water surface WTS. These systems
are usually constructed with several sections, or cells, separated
by weirs that can be used to control water level and flow rate.
Water is treated primarily through assimilation of nutrients and
other pollutants by microorganisms in the substrate and attached to
plant stems and roots. Plant species selected for these systems
often contain large amounts of aerenchyma and are efficient in
translocating oxygen from the atmosphere to their root zones, which
allows respiration by microorganisms. The most effective WTS are
marshes that support herbaceous emergent and submergent plants
(Hammer and Bastian 1989). Wetland treatment systems are being
used for a variety of purposes, including treatment of municipal
and home wastewater (U.S. EPA 1988a, Conway and Murtha 1989), acid
mine drainage (Brodie et al. 1989), landfill and industrial
wastewater (Staubitz et al. 1989), nonpoint source pollution
(Dickerman et al. 1985, Costello 1989), and urban stormwater (King
County 1986). ;
Role of EPA in WTS Operations
One objective of the Clean Water Act is to restore and
maintain the physical, chemical, and biological integrity of waters
of the United States by eliminating discharges of pollutants (Yocum
et al. 1989) . The EPA is responsible for implementing the Clean
Water Act and associated regulations on the release of wastewater
into the nation's natural bodies of water. Discharges must meet
requirements set in a National Pollutant Discharge Elimination
System (NPDES) permit issued by EPA or a delegated state (Davis and
Montgomery 1987). According to the Clean Water Act, most natural
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wetlands are considered to be "waters of the United States".
Presently, WTS.are usually not considered waters of the United
States (Bastian et al. 1989); therefore, discharges to these
systems are not regulated by EPA under the Clean Water Act.
Discharges from WTS to waters of the United States, however, must
meet NPDES requirements. Consequently, EPA must evaluate the
capability of WTS to meet water quality standards under Sections
401 and 402 of the Clean Water Act.
In addition to water quality, habitat quality and the
potential for risks to wildlife by substances in wastewater are of
concern to EPA (Davis and Montgomery 1987). Wetland treatment
systems attract wildlife and, as a result, cannot be considered
isolated operations. The EPA needs to develop methods for
assessing and monitoring the ecological condition on WTS and to
coordinate them with methods used for natural, restored, and
created wetlands.
Assessing Wetland Function and Ecological Condition
Wetland treatment systems can duplicate structural aspects of
natural wetlands, but little is known about their ability to
replicate wetland functions. Wetlands usually perform one or more
functions, depending upon their type, location, the local geology,
topography, and hydrology, and other characteristics of the
watershed. Typical wetland functions include: wildlife habitat;
recreation; nutrient and pollutant assimilation and retention;
detritus and dissolved nutrient and organic matter production;
reduction of downstream sedimentation; floodwater retention; and
groundwater recharge. Wetland functions other than nutrient and
pollutant removal are considered "ancillary", or supplemental in
WTS because these systems are usually designed for wastewater
treatment and not necessarily for other purposes. Wetland
treatment systems can and do provide various ancillary functions,
but concerns exist about potential contamination and effects on
wetland ecological condition caused by the addition of wastewater
(Godfrey et al. 1985, US EPA 1984, Mudroch and Capobianco 1979).
The ecological condition, or "health" of a wetland refers to
its viability, sustainability, and ability to serve one or more
functions. A healthy wetland exhibits; structures and functions
necessary to sustain itself and is free of the effects of most
known stressors or problems (Rapport 19«9, Schaeffer et al. 1988).
Use of Indicators
The ecological condition of a wetland can be assessed and
monitored on the basis of various attributes, or indicators.
Indicators can be measured and used to assess, and monitor
ecological condition and to identify potential problems or
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failures, such as eutrophication, low species diversity,
contamination, and food chain malfunction. Indicators can be
measured or quantified through field sampling, remote sensing, or
analysis of existing data. Although many potentially valuable
indicators exist, it can be most efficient to identify a suite of
indicators that best describes the overall condition of the wetland
resource.
Use of the Wetland Evaluation Technique
Rapid assessment techniques also can be used to evaluate
wetland ancillary functions and values. One of these, the Wetland
Evaluation Technique (WET) (Adamus et al. 987), was tested on three
of the six WTS in this study. The evaluation is based on a
computer analysis of answers to yes/no questions about a wetland.
WET rates functions and values in terms of social significance,
effectiveness, and opportunity. WET evaluates these three
parameters by characterizing a wetland in terms of its physical,
chemical, and biological attributes (Adamus et al. 1987), taking
into account both internal, site-specific attributes and
characteristics of the surrounding landscape. Social significance
is the value of a wetland to society based on its special
designations, potential economic value, and strategic location.
Effectiveness is the capability of a wetland to perform a function
because of its physical, chemical, or biological characteristics.
Opportunity is the chance a wetland has to perform a function based
on inputs from the surrounding landscape.
The analysis assigns ratings of high, medium, or low based on
the probability that the wetland serves a particular function. WET
rates the following functions and values:
Groundwater recharge,
Groundwater discharge,
Floodflow alteration,
Sediment stabilization,
Sediment/toxicant retention,
Nutrient removal/transformation,
Production export,
Wildlife diversity/abundance,
Wildlife diversity/abundance
Wildlife diversity/abundance
Wildlife diversity/abundance
Aquatic diversity/abundance,
Uniqueness/heritage,
Recreation.
breeding,
migration,
wintering,
The technique was designed primarily for conducting an
initial, rapid evaluation of wetland functions and values. It is
not intended to produce definitive ratings of wetland functions.
The ratings represent only the likelihood that the function is
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present. WET is intended to be used as only a part of the wetland
evaluation process. I is not intended to replace professional
opinion and the use of other evaluation methods.
Factors Affecting Habitat Quality
Wetland treatment systems often provide wildlife habitat as an
ancillary benefit (Piest and Sowls 1985, Sather 1989). Nutrient
additions usually increase net primary productivity (Guntenspergen
and Stearns 1985) and promote waterfowl production (Cedarquist
1979). Alternatively, extremely high nutrients and lack of
variation in water depth can encourage establishment of macrophyte
monocultures with lower habitat value (Fetter et al. 1978, Kadlec
and Bevis 1990).
Nutrient enrichment in eutrophic and hypereutrophic systems
can cause algal blooms, resulting in highly variable dissolved
oxygen concentrations and reduced light penetration. The latter
condition greatly affects plant species diversity and distribution,
particularly of submergent species. The species and extent of
aquatic macrophytes can affect the abundance and diversity of
aquatic invertebrates (Dvorak and Best 1982, Reid 1985, Voights
1976); subsequently, plant-invertebrate associations influence use
by waterfowl (Krull 1970, Teels et al. 1976). Wetland morphology,
location, and hydrologic regime also interact to influence habitat
quality.
Wildlife can be exposed to pollutants when using WTS.
Although municipal discharges to wetlands are regulated by state
and federal agencies and industrial discharges are not recommended
for WTS, occasional exceptions or violation of regulations can
result in at least temporary discharge of potentially harmful
substances into WTS. Some animals can be affected through
exposure, ingestion, or bioaccumulation of these substances. In
some places, viral or bacterial diseases such as avian botulism can
be promoted by draw-downs and other hydrologic manipulations.
Detailed information about potential effects of wastewater on
wetland animal communities, however, is lacking in the literature
(Brennan 1985).
Research Objectives
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To date, no comprehensive, large-scale studies of the
ecological condition and wildlife use of WTS have been conducted
(Bastian, personal communication, U.S. EPA, Washington, D.C.).
Because the use of these systems is increasing, knowledge of their
ecological functions, ancillary roles, and potential problems is
needed. Determining the level of sustainability of these systems
as wildlife habitat over the long term is also important.
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This pilot study was designed as an exploratory effort to
examine research methods, indicators\:t logistics, and capabilities.
It is a preliminary assessment of the wildlife habitat quality in
WTS. The study was not intended to provide probability samples to
statistically characterize a defined population of WTS. However,
many of the conclusions about wildlife habitat quality drawn from
the data collected could be used to design future research on the
ancillary values of WTS.
The objectives of the study were:
• to assess the usefulness of methods and indicators for
evaluating the wildlife habitat quality of WTS,
• to identify any major differences in values of wildlife
habitat indicators in WTS and non-WTS, and
• to provide baseline data and identify approaches for a more
focused follow-up project that will provide specific
information to develop measures of the wildlife habitat
quality of WTS.
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METHODS
Sampling and habitat quality assessment were performed at six
WTS. The same general framework and study design were used for
conducting work at all sites. Pilot study results, however, are
reported in three separate EPA documents, each dealing with two
sites: 1) western sites (this report); 2) Florida sites (titled
Habitat Quality Assessment of Two Wetland Treatment Systems in
Florida—A Pilot Study); and 3) Mississippi sites (titled Habitat
Quality Assessment of Two Wetland Treatment Systems in Mississippi-
-A Pilot Study [McAllister 1992]).
Pilot Study Overview
The following is a discussion of the design of the overall
pilot study, including the selection of the six WTS sites, the
indicators chosen for measurement, and the field sampling schedule.
Site Selection
In 1991, six free water surface municipal WTS in the United
States (Table 1) were chosen for sampling based on the following
criteria:
• location in the arid and semi-arid West or the
Southeast so that WTS in two different geographic
and climatic regions of the country could be
studied,
• representing a range of sizes,
• representing a range of ages but in operation for
at least one year,
• the availability of water quality data for use in
indicator analysis,
• permission to use the site, and
• interest of site operators and other groups in
collaboration.
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Table 1. Names, locations, construction dates, and sizes of WTS
sampled in the pilot study.
Site Name ; Location Year Built Size (ha)
Show Low Show Low, AZ 1980 284.0
Incline Village Incline Village, NV 1985 198.0
Collins Collins, MS 1987 4.5
Ocean Springs Ocean Springs,-MS 1990 9.3
Lakeland Lakeland, FL 1987 498.0
Orlando Orlando, FL 1987 486.0
Habitat Quality Assessment
Two general assessment techniques were evaluated for use in
assessing wildlife habitat quality as an ancillary benefit. To
evaluate the first technique, selected indicators of habitat
quality were measured. Indicator data were acquired in the field,
from existing data sets, and from aerial photographs. For the
second assessment, an evaluation of wetland ancillary values,
including function as wildlife habitat, was performed at half of
the sites sampled using the Wetland Evaluation Technique (WET)
(Adamus et al. 1987).
Habitat quality was assessed mainly with respect to birds
because birds were used as a faunal indicator in the project. More
species of birds than of mammals are dependent on wetlands, thus
more literature exists on wetland habitat requirements of birds.
Many of the habitat components necessary for birds are also
beneficial to mammals (e.g., cover extent and diversity, food
resources, a landscape habitat mosaic). Field data were collected
in July 1991 according to the schedule shown in Table 2.
Table 2. Pilot study field sampling schedule.
Sampling Location Dates
Incline Village, NV July 8-12
Show Low, AZ July 19-23
Ocean Springs, MS July 30-Aug. 3
Collins, MS Aug. 6-9
Orlando, FL Aug. 14-19
Lakeland, FL Aug. 19-23
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Measurement of Indicators
A suite of indicators was chosen for measurement at the WTS
sampled (Table 3) . Indicators were selected based on the
likelihood that
• sample collection, processing,, and labor costs would not
exceed budget constraints,
• data collection would be logistically possible, given
available human resources,
• adequate data could be collected within the 4-5 days
spent at each site,
• chosen indicators could be used to effectively
characterize and evaluate wildlife habitat quality,
• required sampling would have minimal environmental
impact, and
• variability of collected data would be low within each
site and consistent among sites.
Some of these criteria were unknown for some of the candidate
indicators. One of the objectives of the study was to test the
indicators by determining ease of measurement and the quality of
data obtained in relation to the logistics involved in collecting
them. Chosen indicators were grouped into one of three data-source
categories:
•• data collected in the field,
• aerial photographs, and
• existing data sets and records kept for each site.
Evaluation of Ancillary Values Using WET
WET was conducted at three of the six sites: Collins, MS,
Ocean Springs, MS, and Show Low, AZ. The intent was to test its
usefulness in assessing wetland ancillary functions, including
wildlife habitat value. WET was given low priority in the pilot
study, and limited time at some of the larger sites prevented a
complete evaluation.
Western Study
The remainder of this document addresses only the western
portion of the pilot study. This section contains site
descriptions, and field and laboratory protocols.
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Table 3. Indicators of wetland ecological condition measured
during the 1991 pilot study.
Ecological Component Indicators
A. Indicators measured in the field:
Vegetation -Species composition and percent
coverage
-Structural diversity and dominance
-Species dominance
-^•Species richness
Invertebrates -Genus and functional group
composition and relative abundance
-Genera richness
Water -Whole-effluent toxicity tests on
inflow and outflow
Birds -Density
-Species richness
B. Indicators taken from aerial photographs:
Site morphology -Wetland area
-Distance of land/water interface
per hectare
-Distance of edge between selected
cover types per hectare
-Ratio of open water area to area
covered by vegetation
-Relative coverage of selected
vegetation types
C. Indicators obtained from existing data sets:
Water -pH
-Dissolved oxygen
-Biochemical oxygen demand
-Ammonia nitrogen
-Total Kjeldahl nitrogen
-Total phosphorus
-Fecal coliform bacteria
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Site Descriptions
The general locations and layouts of the western sites are
shown in Figure 1. Site design is shown in greater detail in site
maps in Appendix A, and a management/operations contact is given
for each site in Appendix B. Each site is briefly described below:
Show Low. Arizona.
This site lies in the Apache^Sitgreaves National Forest in east-
central Arizona at an elevation of approximately 1920 m (6300 feet)
and includes three major areas: Pintail and South Marshes,
Telephone Lake, and Redhead Marsh (Figure 1). The climate in this
region is semi-arid. Built in a pinyon-juniper forest in 1980, the
site covers approximately 284 ha (700 acres), including 54.2 ha
(134 acres) of surface water, and supports marsh and upland
vegetation. Between Telephone Lake and Redhead Marsh water moves
by sheetflow through a riparian corridor approximately 90-120
meters long, which has been planted with cottonwood, willow, oak
and ponderosa pine. Treatment occurs in eight main ponds that are
widely distributed in the three areas. Ponds are relatively deep
in some places, and most are surrounded by emergent vegetation.
Most of the ponds were constructed with nesting islands, and all
are managed for wildlife use. The system is closed (i.e., there is
no outflow), and water loss occurs through evaporation. The system
is used to treat secondary-treated domestic wastewater and has an
average flow of 5300 m3/day (1.4 mgd). Water level management
activities by the Forest Service's site operator allow some ponds
to go dry during the growing season or in the fall, while water
levels in other ponds increase.
Incline Village. Nevada.
This site is a closed system in an arid climate that is located in
the Carson Valley south of Carson City, NV (see Figure 1). It was
constructed in 1985 and is used to treat domestic wastewater from
Incline Village on the north end of Lake Tahoe. The system covers
approximately 365 ha (900 acres), 122 of which are surface water,
and supports marsh and upland vegetation. Most of the wastewater
is used for irrigation by a local rancher from April through
October, and the wetlands gradually become dry during this period.
The wetlands are used heavily by nesting and migrating waterfowl.
Secondary-treated wastewater is piped down the mountain from
Incline Village to the wetlands. Four constructed cells, each
consisting of four subcells, lie adjacent to natural wetlands (see
Appendix A), which are fed by a natural hot spring. Water flows in
a serpentine fashion through all cells. Connections from cells 3
and 4 to the natural hot spring wetlands cause the two types of
water to be mixed together in cell 5. Average flow is 4920 mj/day
(1.3 mgd).
10
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Field and Laboratory Methods
The following is a description of the methods used for all
activities during the field season in July, 1991, and the
laboratory analysis of water and invertebrate samples. The
activities described are: site characterization; vegetation,
invertebrate, water, .and bird sampling; invertebrate and water
laboratory analyses; and evaluation of ancillary values.
Indicators measured in the field or calculated are listed in Table
3.
Site Characterization
Site characterization included gathering information about the
layout of the site and the distribution of major vegetation types,
photographing the major habitat types on site, and recording
wildlife species observed.
The first task at each site was to drive and/or walk around
the entire site and along all interconnecting dikes to roughly map
the locations of major vegetation types, open water, bare soil,
roads, and rookeries visible from the dikes. Cover type boundaries
were delineated on available site maps., This exercise provided
cover maps of dominant plant species to verify aerial photo
interpretation and to ensure that vegetation transects could be
sited representatively.
Vegetation Sampling
Vegetation sampling was the highest priority task for the
field study. It included transect establishment through major
cover types at each site, cover estimation at points along
transects, plant specimen preservation, and identification of
unknown plants by local botanists. The collected data were used to
calculate the indicators listed in Table 3(A).
Transeci
Transect placement required judgement based on the initial
site survey and the distribution of vegetation types. In general,
the transects were placed
• parallel to the gradient of wastewater treatment or in
ponds with varying degrees of water treatment so that
data could be stratified by cell or pond,
• through the predominant vegetation strata in selected
cells/ponds, and
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• to intersect the dominant plant species represented
within each stratum.
Wetland, area, accessibility to vegetation sample points, and
configuration and size of plant communities were factors considered
when determining the length of individual transects and the number
of sample points along transects.
Because of the large size of both WTS studied, sampling was
not conducted in all ponds or cells. At the Show Low site, ponds
1, 2, and 6 were sampled (Figure 1) because the plant species and
their distribution in those ponds were judged to be representative
of the wetland species present at the Pintail and Redhead Marsh
systems. South Marsh (see Figure 1) was not sampled because it was
dry during the sampling period. Telephone Lake was not sampled
because site managers were raising water levels in the lake, and
most of the shoreline vegetation was flooded or dead, and the
degree of water treatment was the same for water entering the
Pintail and Telephone systems, whereas water entering Redhead had
been treated in Telephone Lake and the riparian area (Fig. 1); it
was of interest to examine any changes in biota that might result
from different levels of treatment, and focusing on both three-pond
marsh systems seemed to be the best approach. At the Incline
Village site, cells 1-5 (Appendix A) were sampled because they were
the only ones at that time of year containing water. Also, because
all of the water flowing through the constructed cells 1-4 was
wastewater, sampling them was the highest priority for meeting the
objectives of the study.
Nine transects were established at the Show Low site, and five
were established at the Incline Village site. Spacing of sampling
points along transects depended on the length of the transect, the
size of the wetland, and the sizes of vegetation patches along the
transect. At the Show Low site, separate transects were
established in several ponds perpendicular to the shoreline and
extending into the ponds until depth exceeded approximately one
meter. Transects began at the wetland edge, where hydrophytic
plants or hydric soils were present, and extended into the wetland.
Upland habitats were not sampled unless a transect intersected an
island within the wetland.
At the Incline Village site, transects began at the inflow end
and ran toward the opposite end of the wetland. Much of the site
dried up during the summer, and sampling was done across areas
which, although dry at the surface, were considered to be part of
the wetland basin. We sampled at least 40 points per WTS site.
Transect locations are shown on site maps in Appendix A.
Cover Estimation
Vegetation was sampled at predetermined intervals along
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transects. One, two, or three plots were established at each
sample point along the transect, depending on the structural types
of vegetation present. A 1-m2 quadrat was used for sampling
herbaceous vegetation (emergent, submergent, floating-leaved,
grasses, and forbs). Herbaceous vegetation included species that
colonized dried wetland basin areas. A 5-m2 quadrat was used for
shrubs and trees 0.5-6.0 m tall, and a 10 m radius circle was used
to sample trees >12.5 cm diameter at breast height and >6 m tall.
We recorded the scientific names of all species found within
each plot and estimated absolute percent cover of each as close as
possible to the following categories: 1, 5, 10, 20, 35, 50, 65, 80,
90, 99, or 100 percent. The estimate was made of the undisturbed
canopy of all plant species that fell within each plot even if
plants were rooted outside of the plot. No effort was made to
adjust for discontinuities in the canopy of species with open
growth habits or in the coverage of small floating-leaved species
such as Lemna. Because species overlap each other, the sum of
cover percentages often exceeded 100%. The estimates included only
vegetation that was visible, so submerged species were often not
recorded but were noted as being present. Both members of the
field crew discussed cover percentages for each species in each
plot and together agreed on an estimate.
For herbaceous plots (1-m2), the most predominant stratum (or
cover) type was recorded as one of the following: emergent-Tyjaha,
emergent-.Sci.rpus, emergent-other dominant, emergent-mixed species,
submerged, floating-leaved, and open water. The strata type for 5-
m2 plots was scrub/shrub, and for 10-m radius circular plots was
forested. In addition, each species recorded was assigned to one
of the following layers (or structural types): submerged, emergent
(or herbaceous) , scrub/shrub, forested,, floating-leaved, or dead
(standing or fallen).
Plant Specimen Preservation and Identification
Unknown plants were collected, coded, and pressed for later
identification. Botanists who assisted with identification are
listed in Appendix B.
Invertebrate Sampling and Identification
A semi-quantitative dip-net sampling method was used for
collecting invertebrates. Collection techniques were qualitative,
but the picking of invertebrates from nets was timed so that their
numbers could be expressed per unit time and in relative
abundances. This approach has been used in various forms to make
general assessments and to determine relative abundance of the taxa
of aquatic insects (e.g., Plafkin et al. 1989, Merritt and .Cummins
1984, Tucker 1958, Smith et al. 1987, Brooks and Hughes 1988,
14
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Jeffries 1989, Voights 1976). This method was chosen because the
objective of the pilot study was to determine richness and relative
abundance of taxa found at the time of sampling. Because study
protocols did not require statistical comparisons, quantitative
samples per unit area were unnecessary. The semi-quantitative net
method requires less time, labor, and equipment and has been shown
to sample more taxa than quantitative methods such as Hester-Dendy
samplers and sediment cores (Wallace, personal communication,
Environmental Consultants, Gainesville, FL).
We used rectangular kick nets with #30 mesh. Sample points
were distributed among cells and within different vegetation
habitats. Because both WTS are large, not all wetland cell-habitat
combinations were sampled. Where several adjacent cells supported
similar plant communities, we arbitrarily selected a subsample of
cells and habitats to sample. Invertebrates were sampled in cells
1-5 at the Incline Village site and in ponds 1-3 and 6-8 at the
Show Low site. Rationale for the selection of those particular
cells or ponds is given in the Vegetation section above.
Invertebrate sample point locations are shown on the site maps in
Appendix A.
Two people sampled each cell-habitat simultaneously. Effort
was apportioned between the two team members by dividing areas in
half. Sweeps were taken along the wetland bottom, around plant
stems, and along the surface where floating-leaved species were
present. After taking several sweeps with a kick net in one
habitat, contents of the nets were placed into an enamel pan, and
invertebrates were picked out by hand or with forceps. All
specimens were placed into 95 percent ethyl alcohol preservative in
a pre-labeled glass jar.
When invertebrate densities were high, we estimated numbers
and collected a representative sample. Instead of collecting every
individual when some taxa were very abundant, an attempt was made
to spend time searching for new taxa. Team members spent the same
amounts of time netting and picking. Collection was continued
until no new taxa were found. The total netting and picking time
for both team members was recorded so that abundance could be
expressed as the number of individuals of each taxon collected per
person-hour of collection time.
Invertebrates were identified by biologists at the University
of Minnesota-Duluth (Appendix C) . Collection jars were emptied
into a glass pan and sorted by life stage and order or family.
Individuals were identified to family and genus using a microscope
and the taxonomic keys listed in Appendix C. If a sample jar
contained over approximately 100 invertebrates, counts were made
with the aid of a 12.5 x 10 cm plexiglass tray. An S-shaped trough
in the tray, 2 mm deep and the width of one microscopic field, was
filled with water so that specimens could be moved through quickly,
yet counted individually. Each genus was placed into one of the
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following functional groups: shredder, collector, predator,
scraper, and piercer (Merritt and Cummins 1984). Because Merritt
and Cummins sometimes list two functional groups for a genus, both
were specified when data were recorded. All functional groups
except piercers are defined by Vannote and others (1980). Merritt
and Cummins (1984) define piercers as insects that suck
unrecognizable fluids from vascular hydrophytes. Functional groups
were not assigned to terrestrial invertebrates or to immatures that
could be identified only to family.
Invertebrates of the class Oligochaeta (aquatic earthworms)
were keyed only to family based on external characteristics. They
were counted by totaling the terminal ends collected and dividing
by two. Functional groups were not assigned to Oligochaeta.
Chironomids were divided into groups based on external features.
A few individuals from each group were then mounted on microscope
slides for identification to genus. All individuals in each group
were then assumed to be the same genus. Partial invertebrates were
counted if a head was present, with the exception of snails for
which whole shells were counted regardless of whether the animal
was present.
Whole Effluent Toxicity Testing
One-liter grab samples of water were collected at or near the
inflow, where water had not yet received wetland treatment.
Samples were also collected at some point distant from the inflow
to represent outflow because neither WTS has an actual outflow. We
as assumed that water had received a relatively high degree of
wetland treatment at the point representing outflow.
The inflow sample at the Show Low site was taken from the
spillway leading from the polishing ponds to the chlorination area.
The sample representing outflow was taken from the northwest side
of pond 7. The inflow sample at the Incline Village was taken from
a small pool in cell 5A, which was receiving an intermittent supply
of water directly from the treatment jplant during the sampling
period. On the day that water samples had to be collected, water
was not flowing into cell 5A because water was being diverted from
the treatment plant for use by a local rancher, so the water sample
was collected from the pool just under the pipe. The sample
representing outflow was taken from the south side of cell 4D
(Appendix A).
Samples were shipped on ice to the Environmental Research
Laboratory in Duluth, MN (ERL-Duluth). Samples arrived at the
laboratory for acute and chronic whole-effluent toxicity tests the
day after they were collected (<36 hours). The purpose of the
tests was to determine whether toxicity is a problem at the sites
studied so that it could be examined more closely in future
studies.
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Upon arrival of water samples at ERL-Duluth, the following
routine measurements for whole-effluent toxicity testing were
taken: alkalinity, hardness, ammonia (N:NH3), total residual
chlorine, and temperature. Standard laboratory operating
procedures of the National Effluent Toxicity Assessment Center
(ERL-Duluth) were used (US EPA 1988b). Chronic toxicity tests were
conducted for 7 days with renewal of test solutions every other
day. Lake Superior water was used for a performance control, and
undiluted inflow and outflow samples from the Show Low and Incline
Village WTS were tested.
Aliquots of each sample were slowly warmed to 25°C before use.
Ceriodaphnia dubia (water flea) six hours old or less were obtained
from the ERL-Duluth culture. Ten replicates for each sample and
the control were used in the tests. Each replicate comprised one
organism in 15 mL of test solution contained in a 1-oz. polystyrene
plastic cup. Block randomization was used. The Ceriodaphnia dubia
were fed daily 100 uL of a yeast-cerophyll-trout food mixture and
100 uL of algae, Selenastrum capricornutum. Initial measurements
of pH, temperature, conductivity, and dissolved oxygen were taken
after each sample was warmed and before each renewal. The mean
young produced per original female and the mean percent survival
were recorded after seven days. .
Fathead minnows (Pimephales promelas) 24 hours old or less
were obtained from the ERL-Duluth culture for acute tests. Two
replicates of each sample and the control (Lake Superior water)
were used. Each replicate comprised ten fish in 15 mL of test
solution contained in a 1-oz. polystyrene plastic cup. The test
solution was not renewed, and the fish were not fed. The mean
number of surviving minnows was determined after 96 hours and
expressed as a percentage of the total present at the beginning of
the test.
Bird Surveys
Data on bird use of the wetlands were acquired for the Show
Low site by surveyors from the Audubon Society and the White
Mountain Land Surveys, and for the Incline Village site by the
Nevada Department of Wildlife (Appendix B). Survey methods and
schedules are described below for each site.
Show Low. Ground surveys were conducted weekly from late March
through September, 1991, during early morning. Birds were surveyed
at 10 observation points at the Pintail and Redhead Marsh systems
(see Appendix A). Three additional survey points were established
on Telephone Lake (Figure 1). Observation areas at each point were
defined within ponds by natural boundaries. The objective of the
survey was to count every duck, coot, grebe, cormorant, shorebird,
wading bird, and gull during a 10-minute period at each observation
point. The presence of passerines and raptors was noted, but these
17
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groups were not counted. Double-counting and disturbance to the
birds were avoided. Existing vegetation and dikes were used to
screen the observers' approach to observation points. Observation
teams normally consisted of an observer and a recorder. Counts
from observation points were totalled for each marsh system.
Incline Village: Ground surveys were conducted weekly from early
April through late May and biweekly from late May through early
November, 1991. Surveys were conducted from a truck by driving
down dikes and counting the birds seen. The number of each species
was recorded on each date for all ducks, geese, coots, rails,
shorebirds, herons, grebes, gulls, terns, raptors, and ravens.
Surveyors used 7 or 8 power binoculars arid 20 power spotting scopes
to aid in identification. Separate counts were made for the
constructed and natural wetland units of the site. The constructed
portion included diked cells 1-8; the natural wetland is the ho^-
spring wetland in the southeast corner of the site (see Appendix
A) . Only the areas of the site containing water were surveyed.
Thus, as the season progressed and water dried up, a smaller
proportion of the site was actually surveyed.
In addition, four aerial waterfowl surveys were completed on April
12, May 15, September 26, and November 20, 1991. Ducks and geese
were counted and identified to species. Shorebirds, herons,
grebes, gulls, and raptors were not surveyed. No attempt was made
during aerial surveys to separate counts at the natural wetlands
from those at the constructed wetlands. Other natural wetlands
surveyed for comparative purposes as part of the aerial surveys
included: the Carson River from the Nevada State Line to a point
upstream from the Incline Village site; the Carson River from the
point upstream from the Incline Village site to a point downstream
from the site; Mud Lake, a natural playa situated in the south end
of the Carson Valley south of Minden; a diked created wetland on
the south end of Washoe Lake in the Wasltioe Valley north of Carson
City; and the remainder of Washoe Lake. These areas were judged by
the surveyors to be the most appropriate wetlands for comparison
with the WTS because of their locations adjacent to and in the same
migratory corridor as the WTS, their geology, and their physical
characteristics.
Evaluation of Ancillary Values
WET was conducted at only the Show Low site (Redhead Marsh
pond #6) to test its usefulness in assessing wildlife habitat
quality and other ancillary functions of WTS when applied in
conjunction with field sampling. The evaluation was conducted as
the final component of field work because many of the questions in
the WET assessment require knowledge about the site that can be
acquired during sampling. Many of the questions should be answered
in the field, whereas others require the use of maps and soil
surveys and consultation with local people familiar with the
18
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region. Two people answered the questionnaire together so that
questions could be discussed and answered most accurately. Site
managers were consulted about questions that could not be answered
without additional knowledge of regional physical, geographical,
climatological, and seasonal patterns.
Site Morphology
Color infrared photographs were taken of each site in summer
1991 by local aerial survey companies (Appendix B). Photos were
overlapping with a scale of approximately 1:5000. Photos from the
Incline Village site were not interpreted because the red tones of
vegetation were not discernible on photos and thus cover types
could not be distinguished. The reason for the poor resolution is
unknown.
Photos from the Show Low site were encased in mylar, and the
major cover types were hand delineated on the mylar and labeled.
Cover types that were delineated depended on the plant communities
present and which could be consistently resolved based on different
colors, shades, and textures on photographs and on ground truth
mapping done during reconnaissance. The major cover types
delineated at the Show Low site were emergent, submerged, moist
soil, herbaceous, flooded junipers, moist upland species, upland
grasses, bare ground, and open water.
When vegetation was sparse but all of the same type, small
interstitial gaps in cover were ignored and the area was delineated
with only one polygon. If two vegetation types were distributed
evenly over the same area, the polygon was labeled as both types,
and the area was counted twice. Therefore, the sum of the areas of
different vegetation types on the site could exceed the total
vegetated area. If floating-leaved plants could not be seen on the
photos due to dense growth of overstory species, they were not
included in polygons even if it was probable that they were
present. Polygons were electronically digitized. Data were
entered into the ARC/INFO geographic information system and
estimates were calculated for the indicators listed in Table 3(B).
Calculations are described in the Data Analysis section below.
Acquisition and Use of Existing Data on Water Quality
Under state and federal regulations, WTS operators are
normally required to sample certain water quality parameters to
comply with standards set for discharge to waters of the U.S.
Although the two western sites have no discharge and water quality
monitoring is not required, site operators acquire some water
quality data for their own performance records and often are
required to meet treatment plant effluent requirements.
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The city of Show Low routinely samples water at eight points
throughout the WTS. Sampling in the constructed ponds is done
bimonthly. Samples from the Show Low site are analyzed by Western
Technology Laboratory in Flagstaff, AZ. Data were obtained for
December 1990 through November 1991.
I
The site operators collected water samples from approximately
10 points within the Incline Village site from January 1988 through
April 1990. Surface water sample collection was discontinued in
mid-1990 and may be resumed in the future if resources permit.
Dissolved oxygen samples have been collected monthly at the inflow
to the site since January 1990, and data, were obtained for January
1990 through June 1991. Samples from the Incline Village site are
analyzed by the Incline Village General Improvement District
Laboratory in Incline Village, NV. Table 4 shows the parameters
for which data were available at each site.
Data from only some of the collection points within each WTS
were used for calculations in this study. Data representing a low
degree (LT) and high degree (HT) of wetland treatment were desired
for examining a range of water conditions present in each WTS.
Data from sampling points near the inflow of the WTS were used to
represent LT, while data from sampling points distant from the
outflow of the WTS were used to represent HT.
At the Show Low site, data from pintail Marsh (pond 1) and
Telephone Lake were used to represent LT, and data from Redhead
Marsh (pond 6) were used to represent HT (Figure 1). At the
Incline Village site, water flow and sample collection are limited
in some months by ice. Water is usually routed into cell 1, but in
winter months water is routed into cell 2 if cell 1 is frozen over.
Therefore, water quality data from the outlets of cells 1 or 2 were
used to represent LT; cell 8 data were used to represent HT (Figure
1).
Data Analysis
Descriptive, statistics were calculated to summarize
vegetation, invertebrate, and site morphology data for each wetland
and for each cell or pond within the wetlands. Analysis of data
for each cell was intended to show patterns in indicator values
along a wastewater treatment gradient. Bird counts from all survey
points at each wetland were totaled.
Vegetation, invertebrate, and bird data were summarized using
the Paradox database system. Programs were written in PAL, a
Paradox database programming language. Water quality data acquired
from site managers were analyzed with the Statistical
Analysis System (SAS). Air photo data from the Show Low site were
analyzed using the ARC/INFO geographic information system..
20
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,-J.
Table 4. Water quality data available from each site.
pH=pH (Standard Units); BOD=biochemical oxygen (mg/L);
NH3-N=ammonia nitrogen (mg/L); TKN=total Kjeldahl
nitrogen (mg/L); TP=total phosphorus (mg/L); TFC=total
fecal coliforms (# colonies per 100 mL) ; DO=dissolved
oxygen (mg/L), only inflow (LT) data were available.
Site Parameter
pH BOD NH3-N TKN TP TFC DO
Show Low xxx x x
Incline Village x x x x
Water quality data were summarized by calculating the sample
size, mean, range, and standard deviation for the indicators (e.g.,
pH, total P) measured at points representing the inflow (LT) and
outflow (HT) at each site. When fecal coliform values were
reported as <1, they were entered in the data set as zero. Water
quality indicators were summarized for all sampling dates included
in the time frames specified in the Acquisition and Use of Existing
Data on Water Quality subsection above.
Vegetation data were analyzed for an entire site and for each
cell within a site. Species richness was defined as the total
number of species sampled at a site. Average percent coverage for
a given plant species was calculated by summing cover estimates at
all sample points and dividing by the total number of sample
points. Structural diversity of vegetation was evaluated by
counting the number of structural layers present at a site.
Structural dominance was assessed by calculating the average
percent coverage of each structural layer per site and by
calculating the percentage of species sampled at a site belonging
to each layer. Dominant species were determined by ranking all
species at a site in descending order based on their average
percent coverage and then summing percent coverage values until 50%
was exceeded. All species contributing to the 50% threshold and
any additional species with coverages of 20% or more were
considered dominants.
Analyses on invertebrate data were made by first totaling the
number of individuals of each genus from each sampling point.
Relative abundance of invertebrate genera was calculated by
totaling the number of individuals of each species and dividing by
the total individuals of all genera combined. The percentage of
the total number of individuals belonging to each functional group
(percent relative abundance) was calculated similarly. The number
21
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of invertebrates collected per person-hour was calculated for each
cell and habitat type. Genera richness was defined as the total
number of genera collected at each site.
Counts of each bird species were totaled for all survey points
for each survey at the Show Low site. Survey points were not
established at the Incline Village site; totals for each species
counted during ground surveys were recorded separately for the
natural and constructed wetlands. For each species, the maximum
number of birds detected on a single survey was used to represent
abundance for the survey period. The number of surveys during
which each species was counted was also calculated. Species
richness was derived for all surveys combined by totaling the
number of species detected during the survey period.
The wetland area used to calculate average bird density per
survey at the Show Low site was 54.2 ha, which included the Pintail
and Redhead Marshes and Telephone Lake. Water levels, and thus
wetland area, change much more drastically throughout the summer at
the Incline Village site than at the Show Low site. Because
wetland area was not estimated at the time of each bird survey, the
following procedure was used to calculate wetland area for each
month of the bird survey period (April-November).
Data for surface area of water at the constructed portion of
the Incline Village site were taken from Kadlec and others (1990)
and averaged by month (April-November) for 1987-1989. Therefore,
different areas were used to calculate bird density, depending upon
the survey month. Estimated surface water area for the constructed
portion of the wetland varied from a low of 21 ha in August to a
high of 99 ha in April. Similar data were not available for the
natural wetlands portion of the site. For that area, 42 ha, the
area of surface water during the winter, was used for surveys done
in April through mid-June. Forty percent of the winter area, 17
ha, was the recommended estimate of summer/fall surface water area
given by the site manager and was used for the remaining surveys.
For each waterfowl aerial survey at the Incline Village site,
the total number of ducks, geese, swans, and coots was calculated.
The number of species surveyed represented waterfowl species
richness. The approximate average wetted areas of all sites except
Incline Village were provided by aerial surveyors to calculate
waterfowl densities from aerial counts. For the Incline Village
site, 75 ha of surface water was used to calculate density. This
area of surface water was calculated by summing the monthly average
water areas calculated for ground surveys in the natural and WTS
portions of the site and then averaging the sums over all months.
Indicators were calculated from physical habitat features, of
the Show Low site only, that had been digitized and entered into a
GIS. Calculations were done for the entire WTS and for each pond
as follows:
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o Wetland area was measured as the area within surrounding
dikes or pond boundaries.;
o Distance of the land/water interface is the total length,
of shoreline in a wetland and is a measure of shoreline
irregularity or development; for this calculation, the
area of small floating-leaved plants (e.g., Lemna spp.)
was considered water.
o Length of shoreline (land/water interface) was divided by
wetland area to normalize the shoreline irregularity
estimate.
o Distance of cover/cover interface is the length of edge
between cover types and is a measure of cover type
interspersion.
o The length of edge between different cover types was
divided by wetland area to normalize the estimate of
cover type interspersion.
o The area of open water (no vegetation) was divided by
vegetated area (including floating-leaved plants) to
obtain an index of the relative amounts of the two cover
types.
o Relative coverage of selected cover types (listed in the
Site Morphology section, above) was calculated by
dividing the area of the cover type by the total wetland
area.
Survival and reproduction in whole-effluent toxicity tests
were tested against the controls using Dunnett's multiple t-test
for the chronic tests and a t-test for the acute tests.
Answers to the questions from the WET assessment were entered
into a data set and run through the WET computer analysis to
classify the Show Low WTS according to function. The result was an
assignment of a qualitative probability rating of high, moderate,
or low for each function in terms of social significance,
effectiveness, and opportunity. Results were interpreted
qualitatively, using descriptions of interpretation in the WET
manual as guidelines (Adamus et al. 1987). The evaluation of
social significance consists of two levels of assessment. Level 2
is an optional step to refine the probability rating for
uniqueness/heritage. It was therefore recommended that only level
1 be completed (Adamus, personal communication, Mantech
Environmental Technology, Corvallis, OR).
Comparison Data from the Literature
The indicator values obtained from the two WTS were compared
with data from non-WTS obtained from the literature to put the
information from WTS in the context of what was known about
wetlands in the region. Comparison data were obtained for wetland
physical features, water quality, and bird species richness and
density. The two groups of data were compared to get a preliminary
idea of where the indicator values for WTS lie in relation to the
23
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range of indicator values from other types of wetlands. Data from
palustrine systems, mainly marshes, in the southwestern United
States were used for most of the comparisons. Comparison wetlands
were natural, created, restored, and enhanced. No further attempt
was made to match comparison sites to the WTS sites studied.
Comparisons were made under the assumption that data from the
literature collected in various years are comparable with data
collected in this study. Comparisons were intended to be very
broad and preliminary and to identify gross differences in
indicator values between WTS and non-WTS.
Comparison data were obtained from published documents,
unpublished reports, personal communications, and records from arid
regions of the United States. A library search produced a few
journal articles and agency reports, but many published reports did
not contain the detailed data listing required for summarizing the
indicators of interest. It was also difficult to find data on
specific indicators and regions of the country. Therefore,
regional scientists and resource managers were contacted directly
and asked to provide relevant data.
Quality Assurance
Three types of indicator data were used during this study: (!)
data collected in the field (vegetation, invertebrates, bird use,
whole-effluent toxicity); (2) data derived from maps and aerial
photographs (site morphology); and (3) existing data (water
quality) (Table 3). Laboratory analytical data quality procedures
and data quality objectives (DQOs) for whole-effluent toxicity
testing were based on the ERL-Duluth Quality Assurance Plans and
Standard Operating Procedures (US EPA 1988b). Quality assurance
information was not available from bird surveyors.
At all vegetation plots except QA/QC plots, both members of
the field crew discussed cover percentages of each species in a
plot and together agreed on an estimate. Because solo work was
unnecessary during the 1991 field season, estimates were made by
both crew members together, and evaluation of vegetation QA/QC data
was unnecessary. However, plant identification and percent cover
comparability estimates were calculated for future reference, if
needed.
The following procedures were used to collect and evaluate
QA/QC vegetation data. At 10% of sampling plots a QA/QC check was
performed to determine how similarly the two field crew members
were estimating percent coverage and identifying species. The
decision to designate a plot a QA/QC plot was usually made while
sampling the plot just before it. Each person had a data sheet and
estimated cover percentages separately without any interaction with
the other crew member. Percent cover comparability was computed by
calculating the mean difference between percent cover values
24
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recorded by two team members for each jointly recorded species
(i.e., recorded by both team members in the same plot) at QA/QC
plots. For each team member, percent cover estimates by species
were summed across all QA/QC plots for each species that was
jointly recorded. Mean percent cover estimates for each species
and team member were derived by dividing the percent cover sums by
the number of QA/QC plots in which each species was jointly
recorded. The mean difference was simply the difference in the
mean percentages for each team member. Cover comparability for the
site was the mean comparability for all species. Plant recognition
comparability was calculated by counting the species in each QA/QC
plot that were jointly recorded, dividing by the total number of
species observed in each plot, summing the quotients, dividing the
sum by the total number of plots, and multiplying by 100.
Plant recognition comparability was 100% at the Incline
Village site and 75% at the Show Low site. The mean percent cover
comparability was 95.6% at both sites, which meets the data quality
objective of 85% set prior to the study. It is recommended that
the QA/QC exercises be a part of future field efforts so that, in
the event that crew members must work alone, a record of the
comparability of collected data will be available.
Data QA/QC was also performed in the laboratory at University
of Minnesota-Duluth to check the precision and accuracy of the
identification of invertebrates. Contents of 10% of the sample
jars (of sites combined) were re-identified by a second person.
Subsequently, taxonomic discrepancies were resolved through
discussion and comparison of different taxonomic keys.
Invertebrate identification comparability represents the number of
taxa both people jointly observed and identified during the QA
check. It was computed for each QA/QC sample jar by calculating
the ratio of invertebrate taxons jointly observed to the total
taxons observed and multiplying by 100. Identification
comparability for both sites was obtained by calculating the mean
of all QA/QC sample jars. The mean identification comparability
for invertebrates was 94. This value meets the identification
comparability objective of >85% established prior to the study.
Quality assurance procedures were not used to evaluate the
precision or accuracy in the identification, delineation, or
digitization of habitat types on aerial photographs. The
reconnaissance portion of field work included vegetation mapping,
which served as the best guide and accuracy check for delineation
of cover types on aerial photos. Only one of the field crew
members delineated cover types on all photos so that precision was
maximized.
Existing water quality data were evaluated to determine the
usefulness of water quality parameters as indicators and not to
draw conclusions about WTS performance by using the data in further
analyses. Standard operating procedures and QA procedures were
25
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obtained from the laboratories that routinely analyze water samples
collected at the treatment sites. It was decided, however, that a
careful inspection of the data and QA procedures was unnecessary at
the pilot study stage. Criteria for data assessment had not been
developed, and the process would have been very time-consuming.
Data were intended to be used regardless of laboratory protocols
and measurement consistency among testing labs.
26
-------
RESULTS AND DISCUSSION
This section presents summary data separately for each
indicator group for each WTS. The discussion addresses 1)
indicator and WET suitability for future research, 2) wildlife
habitat quality, based primarily on comparisons to non-WTS data
from the literature, and 3) recommendations for follow-up studies.
It is recognized that study methods (e.g., sample design and
intensity), wetland size, and various other factors confound
comparisons with literature data. Comparisons, however, are used
to establish a context for making general postulations about the
ecological condition of the two WTS studied and for generating
hypotheses for future research.
Vegetation
Species richness (the number of species sampled) was 31 at the
Show Low site. Plants sampled belonged to five structural layers:
emergent, floating-leaved, scrub/shrub, submerged, and dead (Table
5) . The scrub-shrub and floating-leaved layers, however, each
accounted for less than 0.5% of the site coverage. Structural
dominance was generally the same for each pond sampled, with two
exceptions: 1) submerged vegetation was not detected'on transects
at the Pintail Marsh but had an average percent cover of 41% at the
Redhead Marsh pond 6; and 2) Pintail pond 2 had a higher percentage
of dead vegetation than other ponds sampled, probably because water
was not flowing into this pond and the water present was
evaporating.
Species richness at the Incline Village site was 24. Plants
sampled belonged to three structural layers: emergent, submerged,
and dead (Table 5) . Submerged vegetation was found only in cell 4,
where its average coverage was 29%. The dead category at the
Incline Village site composed a substantial proportion of cover (an
average of 35%) and consisted partly of persistent emergent
vegetation (e.g., Scirpus spp. and Typha spp.). Some dead
persistent emergents may contribute to cover for waterfowl or as
nesting habitat for passerines that differs from that supplied by
live plants of the same species.
The emergent layer was by far the most dominant layer at both
sites in terms of the percentage of species comprising it and its
average percent coverage of the site. The emergent layer at the
Show Low site comprised 87% of the species sampled and had an
average percent coverage of 79%; at the Incline Village site; it
comprised 96% of the species sampled and had an average percent
coverage of 54% (Table 5).
Wildlife use of a habitat for nesting and cover is usually
considered to be more dependent on the structure of vegetation
27
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than on the species of vegetation (Beecher 1942, Weller and
Spatcher 1965, Swift et al. 1984).p Well-interspersed vegetation
structures are often associated with high diversity and abundance
of wetland-dependent birds. Complex plant zonation results in
increased numbers of niches available for breeding birds (Swanson
and Meyer 1977, Weller 1978, Dwyer et al. 1979, Ruwaldt et al.
1979, Roth 1976). Observations made at both WTS revealed that the
emergent layer was composed of species of various heights and
structures that were well-interspersed and provided structural
habitat diversity. Although scrub/shrub was a minor structural
component in the sampled areas, it comprised the dominant
vegetative cover in the upland surrounding both sites and could
potentially make a significant contribution to wildlife habitat
from a landscape perspective by providing nesting habitat and cover
for upland and wetland species. Flooded junipers were present at
the east end of the Show Low site pond 6 and, although dead,
provided additional structure.
Submerged vegetation is an important structural component for
wildlife habitat and is present in some areas of both sites.
Submerged species usually provide habitat for fish and
invertebrates, which in turn are eaten by waterfowl and wading
birds. The numbers and weights of macroinvertebrates per unit
weight of macrophyte are positively related to the amount of
surface area available as a substrate and the degree of leaf
dissection (Krull 1970, Dvorak and Best 1982, Biochino and Biochino
1980). Plant form diversity also is likely related to
macroinvertebrate diversity (Dvorak and Best 1982, Lodge 1985).
Potamogeton pectinatus, a submerged species with a branching
structure that creates a large surface area for colonization by
invertebrates, was a dominant species at the Redhead Marsh pond 6
of the Show Low site and in cell 4 of the Incline Village site. It
was also observed in pond 7 at the Show Low site, although that
pond was not sampled for vegetation. Myriophyllum spp., another
branched species with finely dissected leaves, also was present in
ponds 6 and 7- of the Show Low site.
We did not, however, consistently find a greater abundance of
invertebrates in cells with submerged vegetation than in cells
without it (see Invertebrate section below). The lack of
consistent association may be explained by the findings of Teels
and others (1976) who state that the importance of a particular
plant community to breeding waterfowl may depend not only on the
quantity of invertebrates associated with the macrophyte but also
on the time of year at which the plant community appears and its
coincidence with invertebrate production and demand by waterbirds.
Although wildlife use is more influenced by structural
diversity of plants than by the species, the latter are important
with respect to wildlife feeding habitat. Plant species sampled at
each site are listed in Table 6. Tubers and seeds of Potamogeton
29
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spp,, a species sampled at both sites, are consumed by waterfowl.
Japanese millet (Echinochloa crusgalli), which is planted annually
at the Show Low site, produces seeds that are consumed by a variety
of wildlife species. The establishment of this species in a
flooded juniper stand on the south side of Redhead pond 6 has
greatly enhanced waterfowl loafing and feeding habitat (Wilhelm,
personal communication, U.S. Forest Service, Lakeside, AZ) .
Cattail has some importance as cover for wildlife but is consumed
by few species. Cattail and bulrush are used by some species of
birds (e.g., red-winged blackbirds, marsh wrens) for nesting
habitat.
Dominant species at the Show Low site were Hordeum jubatum,
Phalaris arundinacea, Typha latifolia, Potamogeton pectinatus, and
dead emergent species (Table 6) . Phalaris arundinacea was the most
ubiquitous species (found in 29% of the sample plots and in all
ponds), but Typha latifolia was the most abundant (21% average
cover) (Table 6) . The submerged species Potamogeton pectinatus was
dominant (7% average coverage) but was found only in Redhead pond
6, where it had a greater percent cover than any other species.
Other species found only in Redhead pond 6 were Scirpus paludosus
and Myriophyllum spicatum.
Dominants at the Incline Village site were dead emergent,
Distichlis spicata and Juncus spp. Dead emergent vegetation was
the most ubiquitous and the most abundant cover type. Much of the
sampled area was dry and not receiving additional water,
particularly in cells 1-4, so many of the plants had died during
the growing season. Some areas of the site were densely covered by
dead persistent vegetation that was impenetrable and likely had
little value as wildlife habitat. Site managers burn the wetland
once per year to prevent dead vegetation from accumulating and
clogging the system. Mechanical harvesting has also been
considered to alleviate the buildup of vegetation (D. Ritchie,
personal communication, Incline Village General Improvement
District, Incline Village, NV).
One advantage of the arid locations of the two WTS is that
large areas become dry if water flow is reduced for a relatively
short time in the summer months. Drying occurs at the Incline
Village site because water is diverted in the summer to a nearby
ranch for irrigation. Selected ponds at the Show Low site can be
dried because of the flexible water management system that the
Forest Service Ranger District in Lakeside, AZ, has developed
specifically for wildlife habitat enhancement (Wilhelm et al.
1988).
Water drawdowns help to aerate the sediments and plant roots
and often expose substrate on which emergent or submergent plants.
can become established for the next growing season. Few species of
emergent plants can endure permanent flooding. The elimination of
seasonal fluctuation in the hydrologic cycle can therefore reduce
33
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overall plant species richness (Farnez and Bookhout 1982, Sjoberg
and Danell 1983) . Native and perennial species, especially grasses
and sedges, may be replaced by exotic, clonal, annual (commonly
Typha, Scirpus, and Sagittaria) or more aggressive species when
areas are permanently flooded (e.g., Botts and Cowell 1988,
Mclntyre et al. 1988). Because of water flow variation at both
sites, it is possible that emergent plant species are more diverse
than if the sites were permanently flooded.
Conversely, repeated artificial flooding and drying often
results in high salt concentrations in arid regions, which can
restrict the number of species able to persist. Salts were
prevalent at the Incline Village site but not at the Show Low site.
High salt concentration, however, is often a natural condition, so
low species richness should not necessarily be regarded negatively,
particularly if it is similar to that in other wetlands in the
region. It is not possible to determine from this study whether
the salt concentration caused by artificial manipulation of the
hydrologic regime has an impact on plant species richness.
Wetland plant data for comparison were not found for single
wetlands in the arid West. Most data are collected in large
riparian areas and are not directly comparable to data from
individual marshes. Data from reference wetland sites are required
for making a better comparison with WTS.
Vegetation is one of the most significant components of
wildlife habitat. It is directly and indirectly related to
wildlife habitat quality and is a major component of most free-
water surface WTS. Vegetation has also been used frequently to
characterize wetlands and habitat conditions and is often
recommended as a wetland monitoring indicator (e.g., Aust et al.
1988, Brooks et al. 1989, Brooks and Hughes 1988, Brown et al.
1989, US EPA 1983). Sampling methods are well-developed, and
sampling can be completed during one visit to a wetland during peak
seasonal growth.
The continued use of indicators of plant species composition
and abundance for the assessment of function in WTS is highly
recommended. Because structural diversity is an important
component of wildlife habitat quality, future work should include
development of methods for quantifying structure, particularly
within the emergent category, which is usually dominant in WTS.
Comparison data on structural diversity should be found or
collected for evaluating differences between WTS and non-WTS.
Evaluation of habitat quality should focus less on plant species
richness. Estimates of the relative abundance of plant species may
nevertheless be of interest for assessing the wildlife food
availability at a site or whether the site supports rare or
sensitive plants. Species-specific information can be used to
extract various metrics that can be tested for use in habitat
assessment. . '
34
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Invertebrates
A total of 11.1 person-hours was spent sampling invertebrates
at the Show Low site; 8.3 person-hours were spent at the Incline
Village site. The total number of invertebrates collected was 9938
(average of 895 per person-hour) at the Show Low site and 5869
(average of 707 per person-hour) at the Incline Village site.
Thirty-three taxa were collected at the Show Low site, and 35 taxa
were collected at the Incline Village site (Table 7). Different
life stages of the same genus are listed separately in Table 7 but
were not counted as separate taxa.
The family Corixidae in the order Hemiptera dominated at both
sites. The genus Corisella was most abundant at the Show Low site
(41.2%), while immature Corixidae were most abundant at the Incline
Village site (79.6%) (Table 7). At the Incline Village site, all
other taxa had percent relative abundance less than 2%, with the
exception of Corisella (6.2%) and CalliJbaetis (3.9%). Other taxa
with relative abundances greater than 2% at the Show Low site were
immature Corixidae (28.5%), Chironomous/Einfeldia (6.8%),
Hesperocorixa (4.9%), Cpenagrion/Enallagma (4.5%), CalliJbaetis
(2.9%), and Notonecta (2.5%). Non-insect invertebrates comprised
a small proportion of the samples from both sites.
Aquatic insect orders not represented in Table 7 are
Collembola, Plecoptera, Neuroptera, Megaloptera, Hymenoptera,
Trichoptera, and Orthoptera. Plecoptera are usually associated
with clean, cool, running waters or large oligotrophic lakes
(Merritt and Cummins 1984). Aquatic Neuroptera comprise only one
family, the larvae of which are associated with fresh water
sponges. Large numbers of these and the Megaloptera are rarely
seen because they are short-lived and many species are nocturnal
(Merritt and Cummins 1984). Collembolans have a spotty
distribution and are most common in the early spring or late autumn
(Pennak 1978). These characteristics may partially explain the
absence of some aquatic insect orders in the WTS samples.
Many species of Chironomids tolerate low oxygen conditions in
wetlands (Adamus and Brandt 1990) . Chironomid abundance was higher
at the Show Low site than at the Incline Village site (Table 7).
Most of the Chironomids collected at the Show Low site were
Chironomous/Einfeldia, 92% of which were collected in Pintail pond
1 which is generally the first pond, of those that were sampled for
invertebrates, to receive water from the treatment plant. The
Pintail marsh had a higher average biochemical oxygen demand than
the Telephone Lake or Redhead systems (see Water Quality section
below for details), but dissolved oxygen was not measured.
Chironomid abundance and species richness might have been higher if
benthic sampling had been conducted. Benthic sampling is
recommended for future studies to ensure accurate estimation of all
invertebrate groups.
35
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The number of invertebrates collected per hour is related to
density. At the Show Low site, collection rates were highest in
Pintail Marsh pond 3 (1900/hour) and Redhead Marsh pond 7
(1579/hour) (Table 8), both of which were shallow and closed to
water flow. Invertebrates may have been concentrated as water
evaporated. Corisella (family Corixidae) was the dominant genus in
both of these ponds. Collection rates were also high (1718/hour)
in a community of mixed emergent species (Table 9). The community
occurred in Pintail pond 1 and consisted of Eleocharis, Typha,
Sparganium, Polygonum, and Hordeum (Table 9). The high numbers of
invertebrates in this habitat were due to immature Corixidae. The
Pintail Marsh system was more nutrient-rich than the Redhead
system, which might be the reason for a greater abundance of
invertebrates in Pintail pond 1 than in Redhead pond 6 (the two
ponds that normally receive wastewater for each of the marsh
systems). Better water clarity in the Redhead system has been
attributed to the effectiveness of the riparian area between
Telephone Lake and Redhead pond 6 in partially treating the water
before it arrives at the Redhead system (Mel Wilhelm, U.S. Forest
Service, Lakeside, AZ) .
The highest collection rate (4860/hour) at the Incline Village
site occurred in cell 3A in a Juncus habitat (Tables 8 and 9).
Again, the high numbers might have been caused by the concentration
of invertebrates as water evaporated, since no water was entering
cells 1-4. The high count resulted from an abundance of immature
Corixidae. Invertebrate abundance normally increases with
increased nutrient concentrations (Belanger and Couture 1988, Cyr
and Downing 1988, Piest and Sowls 1985, Tucker 1958). Higher
collection rates were expected in cell 5A, where wastewater was
entering the wetland from the treatment plant at the time of
sampling. Invertebrate abundance might have been lower than
expected because water was temporarily entering cell 5A from the
treatment plant and the population might not have responded to the
increased nutrient input.
Higher collection rates were also expected in cell 4D at the
Incline Village site, and cells 6 and 7 of the Show Low site, where
submerged aquatic vegetation was abundant. Submerged plants,
particularly those with finely dissected leaves, serve as a
substrate for invertebrates and have been associated with high
invertebrate densities (Krull 1970, Dvorak and Best 1982). At both
WTS, however, the highest collection rates occurred where submerged
vegetation was absent. It is possible that the period of highest
invertebrate production did not coincide with the appearance of the
submerged vegetation.
Phytoplankton and filamentous algae were observed, although
not quantified, at both WTS and may help to explain the high
invertebrate abundance even in cells without extensive emergent or
submergent plant habitats. In addition to habitat structure, food
availability influences the distribution and abundance of wetland
39
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Table 8. Number of invertebrates collected per person-hour in each
cell at the Show Lowand Incline Village sites.
SHOW LOW
# Invertebrates
Collected/Hour
INCLINE VILLAGE
# Invertebrates
Cell Collected/Hour
."»•.>•;»"»•.
1
2
3
6
7
8
1164
415
1900
364
1579
399
, - •- -- —^^-
1A
2B
3A
4D
5A
5B
133
207
4860
306
309
34
Table 9. Number of invertebrates collected per person-hour in each
habitat type at the Show Low and Incline Village sites.
SHOW LOW
Habitat Type
# Invertebrates
Collected/Hour
Emergent-Scdrpus
Emergent-rypha
Emergent-Eleocharis
Emergent-mixed spp.
Emergent-other spp.
Open water
765
753
902
1718
546
415
INCLINE VILLAGE
Habitat Type
# Invertebrates
Collected/Hour
Emergent-Scirpus 213
Enter gent-Juncus 1693
Emergent-Eleocharis,
Potamogeton 306
40
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invertebrates (Reid 1985). Algal-dominated wetlands may have
exceptionally high diversity and productivity of aquatic
invertebrates. Green algae and diatoms serve as a highly palatable
food source for consumers and, thus, support a higher invertebrate
production (Dudley et al. 1986).
Cell 5B at the Incline Village site had the lowest collection
rate. This area contained large shallow pools often attractive to
waterfowl and was used heavily by ducks and black-necked stilts.
Water levels were 10-15 cm, and the substrate was soft. Low
invertebrate abundance might have resulted from limited
invertebrate habitats or substrates (because of shallow water), or
location of the cell at a great distance from water inflow, causing
it to be less rich in nutrients. Also, the presence of a parched
and cracked substrate suggested that this area had recently been
dried and reflooded, which might have eliminated most of the
invertebrates present.
The majority of invertebrates at the Show Low site were
predators, while the majority at the Incline Village site were in
the unassigned category (Table 10). A total of 4871 invertebrates
(83%) at the Incline Village site and 2998 (.30.2%) at the Show Low
site were not assigned to insect functional feeding groups because
they were not identified to genus (e.g., immatures, terrestrial
invertebrates), were non-insect invertebrates, or were inactive
pupae. The majority of the insects not assigned to a functional
group at both sites were immatures in the family Corixidae. Field
sampling probably coincided with emergence of one or more species
of Corixids.
The distribution of invertebrates among functional feeding
groups is difficult to evaluate because the functional evaluation
of Vannote et al. (1980) is based on lotic systems. Wetlands are
usually predator-based systems (H. Howard, personal communication,
U.S. EPA Region 4, Athens, GA). Although no current protocol
exists for evaluating the viability of, a macroinvertebrate
community of a wetland, comparisons of functional group composition
between reference wetlands and the wetland in question are
sometimes made to identify differences in community structure. In
contrasting a reference wetland to an impacted wetland, biologists
in EPA's Region 4 have observed the elimination in impacted
wetlands of certain taxonomic groups such as amphipods and odonates
(H. Howard, personal communication, U.S. EPA Region 4, Athens, GA) .
Data from the literature that could be used for direct
comparisons to the data collected at the two WTS (e.g., species
richness) were not found. Data collection and reporting methods
used in other studies were not the same as those used for this
study (e.g., collection rate vs. density). Piest and Sowls (1985)
sampled nektonic and benthic invertebrates in ponds at Pintail
Marsh and nearby South Marsh, which also receives periodic inputs
of wastewater from the city of Show Low, and compared densities
41
-------
Table 10. Relative abundances of invertebrate functional groups,
Show Low, AZ, and Incline Village, NV, 1991.
Terrestrial, immature, and non-insect invertebrates were
not assigned functional groups. Relative abundance was
rounded to zero if less than 0.05.
Show Low Site
Functional Group Relative Abundance (%V ;
Predator 54.0
Not Assigned 30.2
Collector/shredder 7.5
Piercer 5.1
Collector 3.0
Predator/collector 0.3
Incline Village Site
Functional Group Relative Abundance.
Not Assigned 83.0 %
Predator 9.0
Collector 4.1
Piercer 2.0
Co Hector/shredder 1.8
P i ercer/shredder 0.0
42
-------
with those found at two nearby lakes in the Apache-Sitgreaves
National Forest that do not receive wastewater. Total densities at
the wastewater ponds were an order of magnitude higher than those
at one of the comparison lakes and several times greater than the
other comparison lake. The largest differences were in nekton
densities between the Pintail Marsh ponds (3180 organisms/m2) and
the two comparison*lakes (74 and 77 organisms/m2) . Invertebrate
abundance was high at both of the western WTS in this study and
likely serves as a good food source for wetland birds.
Macro invertebrates are important to habitat quality and system
function because they serve as a major food source for waterbirds,
fish, reptiles, and amphibians, and they are a critical link
between primary production of systems and higher order consumers
(Murkin and Batt 1987, Murkin and Wrubleski 1987). Because of
their relatively low position on the food chain, invertebrates can
serve as indicators of food chain function and the implications for
higher organisms. Invertebrates are less likely than birds or
mammals to migrate from one wetland to another, they can be sampled
in a relatively short time, and they serve as an indicator of
secondary productivity. Macroinvertebrates have been suggested as
monitoring indicators by various scientists (Brooks et al. 1989,
Brooks and Hughes 1988, Brown et al. 1989, Schwartz 1987, US EPA
1983).
Continued development of this indicator for habitat evaluation
in WTS is recommended. Future development should consider
standardizing collection methods, expanding collection techniques
(e.g., sediment sampling for benthic invertebrates), looking for
relationships between bird use and invertebrate abundance, adhering
to a rigorous experimental design, and simultaneous sampling at
reference sites. Functional group data might be useful for
comparisons with reference wetlands and for future development of
protocols for assessment of invertebrate community viability in
wetlands, but their usefulness as an effective indicator at this
time is uncertain. One problem with the invertebrate evaluation
methods used in this study is that identification to genus is labor
intensive and costly. In future studies, effort should be focused
on testing and developing indicators for which identification to
genus is not necessary (e.g., focus on total number of
invertebrates or relative abundance of benthic and nektonic
invertebrates).
Whole Effluent Toxicity Tests
Toxic effects on reproduction of Ceriodaphnia dubia were not
observed or were not significant in the Show Low samples or in the
Incline Village inflow sample (Table 11). In the sample
representing outflow from the Incline Village site, reproduction
was reduced significantly. The reduction in survival was not
significant. There was no statistically significant toxicity
43
-------
effect at either site in the fathead minnow acute tests; survival
was 95% or more for all samples. Routine measurements done on each
water sample upon arrival at the Duluth laboratory are shown in
Table 12. Initial and final chemistries for water samples and the
controls are shown in Appendix D. ;
Identifying the precise cause of reduced reproduction of
Ceriodaphnia dubia in the sample representing outflow at the
Incline Village site and assessing its implications for other
wildlife would require further study. Reduced reproduction could
be due to the high conductivity present at the collection site.
Conductivity was 4077 umhos/cm (Appendix D) and is likely related
to high salinity caused by surface salts present at the site.
Because high salinity is typical in the arid West, an attempt
should be made to minimize its influence in whole-effluent tests or
other types of toxicity tests if these tests are conducted in
future studies. This influence could be minimized by using water
collected from a local non-WTS site as a control rather than using
a water source near the testing lab, as was done in this case. •
Toxic heavy metals, primarily from industrial sources, and
organic contaminants are sometimes present in municipal wastewater
(US EPA 1984, Hicks and Stober 1989, Richardson and Nichols 1985).
Their concentrations are typically reduced by approximately 30-95%
in secondary treatment before entering a wetland (Richardson and
Nichols 1985). In addition, most constructed wetlands do not
receive water from industries. Although concentrations of toxic
substances are likely to be absent or low in WTS, probably the
greatest risk to wildlife from substances entering in wastewater,
even in low concentrations, is from foioaccumulation. Benthic
organisms inhabiting and feeding in contaminated sediments can
uptake toxic substances bound in the sediments. However, short-
term whole-effluent tests of water will not indicate whether
bioaccumulation is occurring, and the test may not detect it unless
the harmful substance is entering the wetland at the time of sample
collection. Furthermore, tissue analyses conducted to determine
whether bioaccumulation is occurring will be insufficient unless a
connection between tissue levels of contaminants and adverse
effects can be established. Nevertheless, it seems wise to monitor
contaminant levels in sediments or tissues of invertebrates or fish
in wetlands that are suspect (e.g., those that have past histories
of user violations) or where the potential for contamination is
greater (e.g., wetlands receiving industrial inputs). Determining
whether the levels of specific substances, if found, pose risks to
higher forms of wildlife through ingestion, exposure, or
bioaccumulation is then necessary. Early detection and correction
is preferable to remedying a problem after it has occurred.
Although toxicity is an important issue, it is not one that is
related exclusively to wildlife habitat. Depending on public use
of the WTS, it can also become a human health issue. Whole-
effluent toxicity tests are not recommended for future studies of
44
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Table 11. Reproduction and survival of Ceriodaphnia dubia.
Sample
Mean Young/Original Female
(95% Confidence Interval)
Mean Survival
Show Low site
Inflow
Outflow
Control
Incline Village site
Inflow
Outflow
Control
30.6 (28.4-32.8)
24.5 (21.5-27.5)
25.0 (22.1-27.9)
28.1 (23.5-32.7)
5.3 (4.5-6.1)
23*8 (18.6-29.0)
100
100
100
100
70
100
Table 12. Measurements on water samples performed by ERL-Duluth
immediately upon arrival of samples at the laboratory.
Sample
Hardness
(mg/L as
CaCO,)
Show Low site
Inflow
Outflow
Incline
Inflow
Outflow
177
125
Villacre site
300
446
Alkalinity Ammonia
(mg/L as N:NH3
CaCO,) rma/L)
180 <1
213 <1
60 <1
115 <1
TRC*
rma/L)
<0.02
0.06
<0.02
<0.02
TRC=total residue chlorine
45
-------
wildlife habitat quality because they do not provide enough
information for assessing the risk of toxicity or whether
bioaccumulation is occurring. The proper procedure is a much more
lengthy and expensive process than a general assessment of wildlife
habitat quality and thus should remain a separate activity in
selected wetlands suspected as higher risks for the presence of
contaminants. Suspect wetlands might be those where toxic
substances or metals have been found in the past, where wastewater
treatment plant user violations have occurred in the past, or where
routine sampling suggests possible problems (e.g., a sharp
reduction in invertebrate abundance, signs of stress or disease in
birds that use the WTS).
Bird Use
In the first part of this section, results and discussion of
ground bird surveys are presented for both sites. Comparisons are
made with data from the literature on bird species richness and
density. In addition, comparisons are made between data from the
constructed and natural portions of the Incline Village site. In
the second part of this section, results of the aerial bird surveys
conducted at the Incline Village site and five non-WTS sites in the
Carson Valley are presented, and comparisons of indicator values
are made among sites. The third part is a general discussion,
including recommendations for future stxidies.
Ground Survey Results
At the Show Low site, species richness calculated using the
data for surveyed species (waterfowl, wading birds, grebes,
shorebirds, and gulls) from all surveys combined was 42 (Table 13).
This included 15 species of waterfowl and 14 species of shorebirds.
A species list and the maximum number of birds of each species
counted on a single survey from March-September 1991 at the Pintail
Marsh, Telephone Lake, and Redhead Marsh systems is presented in
Appendix E. Species that were not surveyed but were noted as being
present (e.g., raptors, passerines) and the number of surveys on
which they were detected at the Show Low site are also listed in
Appendix E. Adding these species to the surveyed species increases
the species richness at the Show Low site to 125. The highest
richness (62) occurred during the first week of May, and the lowest
richness (26) occurred the first week of June.
Average daily densities of surveyed species varied from 7.8 to
21.7 birds per hectare of wetland, with an average of 13.8 (Table
13). The area used to calculate density was 54.2 hectares, which
included the Pintail and Redhead Marshes and Telephone Lake. ;A
total of 19,440 individuals of waterfowl, shorebirds, and wading
birds (excluding young of the year) were counted during the 26-week
survey, resulting in an average of 748 birds per survey. Waterfowl
46
-------
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I
accounted for 91% of the total (17,690), while shorebirds and
wading birds comprised the remaining 9% (1750).
Twelve of the 125 species observed are classified as
threatened, federally endangered, or sensitive in Arizona. Species
considered sensitive in the U.S. Forest Service Region 3 are
American avocet, belted kingfisher, black-crowned night heron,
double-crested cormorant, sharp-shinned hawk, snowy egret, sora,
and willow flycatcher. The white-faced ibis is in federal category
2 (sensitive), meaning that federal endangered listing may be
appropriate but data are inconclusive. The bald eagle and
peregrine falcon are listed as federally endangered, and the osprey
is threatened in Arizona.
The following nine species were observed at the Show Low site
with clutches or broods during the survey: mallard, gadwall,
cinnamon teal, ruddy duck, pied-billed grebe, American coot, black-
crowned night heron, eared grebe, and double-crested cormorant.
Thirty-two nests were counted in the cormorant rookery at Telephone
Lake. Two other species that are sensitive in Region 3, sora and
American avocet, have also been documented as nesting at the Show
Low site. Two species not detected on surveys, tundra swan and
Canada goose, are winter residents at the WTS (M. Wilhelm, personal
communication, U.S. Forest Service, Lakeside, AZ).
At the Incline Village site, species richness of surveyed
species (waterfowl, wading birds, shorebirds, grebes, gulls, terns,
and raptors) at the constructed and natural wetlands during ground
surveys was 50, including 19 species of waterfowl and 12 species of
shorebirds. Of the 50 species, 47 used the constructed wetlands,
while only 22 used the natural wetlands (Table 13). The three
species unique to the natural wetland were marbled godwit,
Forster's tern, and black tern. Twenty-eight species were found in
the constructed wetlands but not in the natural wetlands.
The following non-surveyed species; (mostly passerines) were
seen in the constructed wetlands during the 5-day field sampling
period in July 1991: great blue heron, turkey vulture, common
nighthawk, bank swallow, cliff swallow, magpie, American crow,
marsh wren, common yellowthroat, yellow-headed blackbird, red-
winged blackbird, brown-headed cowbird, and song sparrow.
The average bird density per ground survey in the wetland
treatment portion of the Incline Village site was 19.1 birds per
hectare. In the natural hot spring wetlands, the average bird
density per ground survey was 2.6 birds per hectare (Table 13).
Because water levels changed so dramatically throughout the season
at the Incline Village site, the area, of water used to obtain
densities was different for each month of the surveys and was
calculated as described in Data Analysis in the Methods section.
Detailed data, including the maximum number of each species
surveyed on a single ground survey and. the number of surveys on
which each species was detected, are shown for the constructed and
natural wetlands in Appendix E.
48 :
-------
Data from the Incline Village WTS showed a higher density and
species richness and a more intensive use by birds for a greater
part of the survey period compared with the adjacent natural
wetland. Waterfowl species that were counted only on the
constructed wetlands were green-winged teal, ring-necked duck,
canvasback, scaup, common goldeneye, and bufflehead. The total
number of ducks counted during any one survey of the constructed
wetlands varied from a low of 18 on November 6 to a high of 1788 on
April 22. Total ducks surveyed on the natural wetland varied from
1 (on 10 dates) to 500 on June 13. Duck use of the natural wetland
virtually ceased after August 2. The Canada goose was the primary
goose species using the wetland; geese were concentrated primarily
in the constructed wetlands. Shorebirds used the constructed
wetlands almost exclusively. Small numbers of only three species -
killdeer, black-necked stilt, and a single marbled godwit - were
observed on the natural wetlands on 5 of 18 surveys. With the
exception of one snowy egret surveyed on May 29, wading birds,
gulls, and grebes were not seen on the natural wetlands. Raptor
use of the study area was more equitably distributed between
natural and constructed wetlands.
Further comparison using data from the literature showed that
species richness at the two WTS studied was above the range of
values reported for other non-WTS in the arid West (4.9-49) (Tables
14-19) . This was true for comparisons of all surveyed birds and of
specific bird groups (e.g., waterfowl, shorebirds) . Although total
species richness could not be calculated for the Incline Village
site because passerines were not surveyed, the 47 species of birds
surveyed is still higher than most comparison data that include all
species (Tables 14 and 15). Furthermore, species richness of all
species at the Incline Village site would be at least 60 when the
13 non-surveyed species that were seen during field sampling in
July are added, which is higher than all values in comparison
tables.
The literature data found for bird density in non-WTS are few
and are not directly comparable to the WTS studied because they
include all species of birds, whereas the WTS data do not because
passerines were not surveyed. Nevertheless, the average density
per survey at the Incline Village site (19.1 birds/hectare, not
including passerines) is still within the range of that in
comparison wetlands in the same region, which do include passerines
(Table 15). The average density at the Show Low site is lower than
the range of densities reported for two habitats in a comparison
wetland (Table 16), but the maximum density reported for the Show
Low site (21.7 birds/ha, not including passerines) is within the
range reported for surveys that included passerines. Bird density
at the Show Low site would likely have been higher than densities
reported for other wetlands if all groups of birds had been
surveyed.
49
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Table 14. Bird species richness at the Wcishoe Lake Mitigation Area,
Nevada. Studies conducted from 1989 to 1991 (from James,
personal communication, Department of Transportation,
Carson City, NV). For comparison, bird species richness
at'the Incline Village WTS, April through November, 1991,
was 47 (not including passerines).
Survey Date
May 1989
June 1989
April-June 1990
June 1990
April-July 1991
Species Richness
24*
• 19*
49
31
35
* Passerines not surveyed
Table 15. Mean species richness and density of birds reported for
wetlands of the Lower Colorado River and the Salton Sea
(from Ohmart and Anderson, 1978) . Incline Village ground
survey results from this study are shown for comparison
(passerines not included).
Species Richness
Incline Village
Density (birds/ha)
(this study)
Salton Sea
Reservoir along
Lower Colorado River
47.0
39.0
4.9
19.1
32.8
0.5
50
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Table 16. Bird species richness and density (all bird species
included) in salt cedar and willow habitats at Picacho
Reservoir, AZ, 1982 (Gatzf personal communication, U.S.
Bureau of Reclamation, Phoenix, AZ) . Show Low survey
results from this study are shown for comparison.
Habitat Species richness Density (birds/ha)
Show Low 125 13.8*
Salt Cedar 25 24
Willow 22 18
* Density was calculated from counts that excluded passerines
Table 17. Waterfowl species richness from Apache-Sitgreaves
National Forest, Arizona, 1979-1980 (from Piest, personal
communication, Arizona Game and Fish Department, Phoenix,
AZ) . For comparison, Show Low waterfowl species richness
from this study was 15.
Site Waterfowl Species Richness
Basin Lake 14
Crescent Lake 9
Dipping Vat Reservoir 9
East of Big 6
Hay Lake 8
Hog Wallow Lake 5
Marsh West of Hog Wallow 2
Jessie Spring 3
Mexican Hay Lake 9
Nelson Reservoir il
Norton Reservoir 8
Nutrioso Reservoir 14
Pool Corral Lake 8
Rudd Reservoir 7
Salt House Marsh 9
San Salvador Reservoir 8
Sierra Blanca Lake 7
Slade Reservoir 9
St. Joseph Reservoir 12
St. Mary Reservoir e
Sunrise Lake 13
Water Canyon Reservoir 7 .
White Mountain Reservoir 13
51
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Table 18. Bird species richness at Stillwater Wildlife Management Area,
and Lahontan Valley/Carson Lake, Nevada, 1989-1991 (Neel,
personal communication, Nevada Department of Wildlife, Fallen,
NV). For comparison, species richness on ground surveys (this
study) at the Incline Village WTS was 47 over an 8-month period
(waterfowl, wading birds, shorebirds, gulls, terns, grebes, and
raptors surveyed).
Stillwater Wildlife
Management Area
August 89
Indian Lake 23
Swan Lake Check 15
Lead Lake 16
Stillwater Point Reservoir 18
Dry Lake 17
Cattail Lake 17
Division Pond
East Alkali
Lower Foxtail —
Goose Lake
Nutgrass South
Nutgrass North
Nutgrass West
Tule North
Carson Lake
Lahontan Valley
Sprig Unit 17
Bigwater
Rice Unit
York Unit
Soda Lakes 15
Mahala Slough 2
South Washoe
Harmon Reservoir 14
Old River Reservoir 14
Shecker Reservoir 8
April 90
7
5
5
10
9
9
6
3
11
9
6
15
6
8
8
12
8
10
4
3
10
**
April 91
14
12
8
9
10
7
10
11
5
6
— no data available
* Shorebirds, wading birds, gulls, terns, grebes, and raptors
** Shorebirds, gulls, terns, and rails
*** Shorebirds, gulls, and terns
52
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Table 19. Shorebird species richness in western Nevada wetlands,
1991 (Neel, personal communication, Nevada Department of
Wildlife, Fallen, NV) . For comparison, shorebird species
richness at the Incline Village site for this study was
12.
Site
Northern Nevada
Soldier Meadows
' Summit Lake
Gridley Lake
Deer Creek Reservoir
Continental Lake
Lemmon Valley
Lemmon Lake
Warehouse Ponds
Pyramid Lake
Mud Lake
Washoe Lake
Species Richness
1
2
8
4
8
7
8
6
5
1
53
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Aerial Surveys Results - Incline Village Site
Aerial waterfowl survey results show that the Incline Village
site was the single most important site for waterfowl of the sites
surveyed in the Carson Valley in 1991 (Table 20) . On aerial
surveys, separate counts were not made at the WTS and natural hot
spring wetlands. Therefore, the Incline Village WTS data are
slightly contaminated by the natural hot spring data, causing
species richness and the total number of birds to be biased high
and densities to be biased low. However, the bias is probably
small because bird use of the natural wetlands is very low relative
to the WTS. A total of 1557 hectares were surveyed during aerial
surveys at the Incline Village and surrounding sites, 10% of which
are at the Incline Village WTS. The Incline Village WTS, however,
contained a proportionately higher percentage of total waterfowl
surveyed (19-46%) on all surveys, including 40-50% of all dabbling
ducks and 49-100% of all diving ducks. Species richness of
waterfowl at the Incline Village site (4-14) was generally higher
than at other sites but was very similar to the Carson River site
upstream (Table 20).
Waterfowl densities calculated from aerial survey data were
also higher at the Incline Village site than at any other site on
all surveys (Table 20). The high density at Mud Lake on the last
survey was due to a large number of Canada geese. The same wett4d
area estimate was used to calculate waterfowl densities for ail
surveys because only crude estimates of areas surveyed were
available from surveyors for sites other than Incline Village, and
because estimates were not made several times throughout the season
as water levels fell. Area calculations for aerial surveys are
described in Data Analysis in the Methods section. Although use of
the same area estimate in all months biases densities high for the
early surveys and low for the later surveys, it allows a better
comparison of the relative numbers among the sites surveyed. Area
estimates for each site surveyed are given in Table 20.
Most of the waterfowl use at the Incline Village site was by
ducks and coots. Geese were most numerous on the Carson River
upstream. The lower numbers and density of waterfowl at the
Incline Village site on the last survey compared with the other
surveys (Table 20) could be a result of hunting on the site in
November. Low numbers of waterfowl at the Department of
Transportation mitigation site and at Washoe Lake during the last
two surveys resulted from completely or almost completely dry
conditions at those sites.
Bird Indicator Discussion
The intensity of bird use at the two WTS studied can probably
be attributed to organic loading, high productivity, and, to some
extent, a more dependable water supply than is found at nearby non-
54
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Numbers:
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55
-------
WTS wetlands. Organic loading increases production of aquatic
invertebrates and thus the abundance and diversity of songbirds
(Hanowski and Niemi 1987) and waterfowl (Belanger and Couture 1988,
Piest and Sowls 1985). The benefits to waterfowl and other species
or wildlife from use of wastewater for habitat enhancement have
been reported previously for both the Show Low (Wilhelm et al.
1988) and Incline Village (Kadlec et al. 1990) sites. Wildlife
benefits in California marshes were reported by Cedarquist and
Roche (1979) and Cedarquist (1980a, 1980b) for wastewater discharge
to natural wetlands and by Demgen (1979) and Demgen and Nute (1979)
for created wetlands.
As a result of drought conditions in the West for about the
past six years, most of the natural wetlands and lakes in the
Carson Valley become dry during the summer. A local rancher begins
to take some of the wastewater for irrigation in early summer, so
the WTS does not receive as much water and slowly dries up
throughout the summer. It does, however, still contain more water
than many of the surrounding wetlands and lakes. WTS are among the
most dependable surface water in arid areas, and they attract a
great proportion of water-dependent birds. The importance of WTS
in the arid West for waterbird habitat is unquestionable. Because
of the shortage or ephemeral nature of natural wetlands in the
West, design and enhancement of wildlife habitat at WTS is
important for wildlife management and production.
Habitat requirements, life histories, and species assemblages
of wetland birds are relatively well-known, although information on
community-level response to particular stressors has been difficult
to collect (Adamus and Brandt 1990). Birds are more visible and
audible than other fauna and are easily identified by trained
biologists, which makes them a relatively reliable measurement in
many cases. Information about bird use is useful for providing
information on other system components, such as the types of food
resources that may be present in the wetland or the .presence of
habitat features required by certain species.
Birds, however, are very mobile, and their use of a wetland
may be erratic, necessitating multiple surveys in a given1 year.
Because of bird mobility, adverse environmental effects, if
detected, often cannot be linked with certainty to a specific
wetland. In addition, one cannot assume that the presence of birds
means good habitat quality, particularly in arid regions where
suitable habitats are scarce and birds are forced to use available
habitat regardless of its condition. Most bird species might be
better as indicators of overall landscape conditions than of single
wetland conditions (Adamus and Brandt 1990). The food resource
(e.g., invertebrates, zooplankton, or fish) might be an equally
reliable indicator for assessing the faunal component of individual
wetlands and is not as mobile. However, laboratory time and
expense are required for identification of invertebrates or
zooplankton.
56
-------
Migratory seasons are the best time to assess optimal foraging
and resting use by birds but.not are ,necessarily the best time to
sample other indicators at the wetland, such as vegetation. If the
goal of future monitoring is to evaluate a wetland in a few days or
less, estimation of bird use may* be grossly biased. Therefore,
bird use should continue to be measured for at least several weeks.
If cost or logistics of extensive bird surveys are a limitation,
one might consider conducting surveys only in the spring and
omitting fall surveys. Spring surveys can provide estimates of use
by migrating and breeding birds. If bird use is an indicator in
future studies and monitoring efforts, the following should also be
considered:
• Unless an accurate estimate of water area can be made on
every survey at all wetlands sampled, bird density should
be omitted as an indicator at sites such as Incline
Village where evaporation results in varying wetland area
throughout the season.
• Indicators such as bird activity (breeding, feeding,
resting) and the presence of threatened, endangered, or
keystone species should be considered to provide more
information about the types of habitat present and its
value to species of interest in a particular region.
• The amount of sampling effort that can be devoted versus
that required to obtain an accurate representation of
bird use, density, and diversity should be evaluated. If
the level of effort possible is insufficient to make
accurate estimates, then objectives should be re-
evaluated, surveys re-designed, or resources allocated to
other indicators.
• A yearly sampling schedule that minimizes survey effort
or repeat visits while assuring that bird use is
accurately characterized should be established.
• A plan for data integration and reduction should be
designed if multiple surveys are conducted. Analysis by
taxonomic group (e.g., waterfowl, shorebirds, passerines)
or feeding guilds should also be considered for assessing
habitat quality.
• Logistics and quality assurance issues involved in
coordinating bird surveys with other agencies,
universities, or organizations and conflicts that might
arise due to diverging interests in the kinds of data
collected should be anticipated.
Future work should continue to include surveys at surrounding
reference wetlands, as was done in Nevada for this study, so that
meaningful comparisons can be made between WTS and non-WTS.
Evaluation of Ancillary Values
Probability ratings of high, medium, and low assigned by the
57
-------
WET analysis to the various wetland functions are given in Table 21
for Redhead pond #6 at the Show Low site. The WET analysis
provides ratings for functions other than wildlife habitat, which
are also included in the table. Of greatest concern with regard to
wildlife habitat are the ratings under effectiveness and
opportunity, which characterize the wetland and surrounding area in
terms of physical, chemical, and biological attributes. Redhead
pond #6 received high ratings under effectiveness for migration and
wintering diversity/abundance and low ratings for wildlife breeding
and aquatic diversity/abundance (Table 21) . Effectiveness was also
rated high for floodflow alteration, sediment stabilization,
sediment/toxicant retention, and nutrient removal/transformation.
Opportunity to perform functions was rated high for floodflow
alteration, sediment/toxicant retention, and nutrient
removal/transformation. Social significance ratings for wildlife
and aquatic diversity/abundance were high. High social
significance ratings were also given to nutrient
removal/transformation and uniqueness/heritage.
The use of WET in WTS presented some interpretation problems
because WET questions did not pertain to the unique circumstances
present in WTS. For instance, WET was designed primarily for
wetlands, either natural or artificial, that function within a
watershed and are connected hydrologically to a larger system.
Although the Show Low wetland receives runoff from the surrounding
upland, most of the inflow is wastewater. Water levels and flow
patterns at the Show Low site are artificial and managed, and the
water regime is not always reflective of a wet or dry season. The
service that WTS provide, as well as their unique hydrologic
characteristics, are not accommodated by some of the WET questions.
Answering these questions requires assumptions and/or guesses that
might affect the results in unforeseen ways. The technique also
requires a large amount of information on surrounding wetlands and
a knowledge of the locality (e.g., geography, geology, land use,
watershed characteristics). Information about the wetland in
question at other times of the year is also necessary.. Local
people familiar with the area must ibe depended on to answer
questions regarding other wetlands and seasons.
The answers to many of the questions were uncertain or
speculative, and results are questionable. Unless field personnel
are experienced with using the technique and are familiar with the
wetland, its surrounding area, and its characteristics in both the
wet and dry seasons, WET can be cumbersome and confusing. There is
also the possibility that the answers given by the WET analysis
will be taken at face value without consideration of other data
collected or professional judgement. Continued use of WET for
assessing WTS is not recommended.
Other comprehensive evaluation methods could be considered for
testing in future research if a rapid assessment method is deemed
necessary to complement indicator data. Some of these methods were
58
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designed for national use while others were designed for regional
use. All of the methods have limitations and none have been
validated extensively. For a more detailed discussion, an overview
of the most commonly used methods is given by Adamus (1992).
Site Morphology
When aerial photos were taken on July 1, 1991, water levels
were considerably low, particularly in ponds 2, 3, and 8. These
ponds contained more moist soil and upland herbaceous species than
emergent or submerged species (Table 22). Hordeum jubatum was a
common colonizer on many of the moist flats, exposed when water
levels dropped, and was the dominant cover type at ponds 2 and 3.
A mix of junipers and emergents dominated at pond 8. Submergent
vegetation was present only in ponds 6 and 7 and was the dominant
cover type at both ponds. Emergent vegetation was the dominant
cover type at pond 1 (Table 22).
Physical features of artificial ponds, such as surface area
and shoreline irregularity, influence waterfowl brood use (Belanger
and Couture 1988, Lokemoen 1973, Mack and Flake 1980, and Hudson
1983). Belanger and Couture (1988) recommend that, for good
waterfowl habitat, artificial ponds should have >30% cover of
emergent vegetation. All of the ponds at the Show Low site have
less than 30% (Table 22). However, plants other than wetland
emergents (e.g., herbaceous species on moist soil and upland
grasses on banks and islands) contribute to wildlife cover and
habitat structural diversity. Accounting for these cover types,
herbaceous cover comprises between 28 and 72 percent of the area at
all basins.
Diversity, abundance, and density of wetland-dependent animals
are usually higher when vegetation and water are well-interspersed
(Steel et al. 1956, Weller and Frederickson 1973). Weller and
Frederickson concluded that marshes with 50-70 percent open water
that is well interspersed with emergent vegetation (or a ratio of
water to cover of (1.0-2.3) produce the greatest bird diversities
and numbers. Weller and Spatcher (1965) noted that maximum species
richness and abundance occurred when a well-interspersed
cover:water ratio of 50:50 [or 1.0] existed. Based on these
findings, the most optimal ratios of open water to vegetated area
were present at Pintail pond 1 and Redhead ponds 6 and 7 (Table
22). The ratio was low at ponds 2, 3, and 8 because they were not
receiving wastewater and were relatively dry from evaporation.
Land/water interface per hectare of wetland is a measure of
shoreline length, commonly considered shoreline development, and is
an indicator of the degree of interspersion of water and cover.
Mack and Flake (1980) found that interface was positively
correlated with dabbling duck production in the prairie pothole
region. Land/water interface per hectare of wetland varied among
60
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ponds at the Show Low site (111-398 m/ha). Because some of the
ponds were drying up (e.g., ponds 2, 3, and 8), very little open
water was left, which made the ratios smaller than they would be at
high water. (The area used to calculate the ratio was that of the
whole basin, including moist areas with no standing water.)
Land/water interface values from the Show Low ponds are within the
range of values £ound for non-WTS (38-500 m/ha) (Table 23).
Land/water interface per hectare of wetland in Redhead ponds 6 and
7 (398 and 321, respectively) falls in the upper end of the range
in comparison with most non-WTS.
The* interface between different cover types is another measure
of interspersion and edge. Wetlands with moderate to high
vegetation richness and interspersion can support a greater density
and species richness (Weinstein and Brooks .1983, Rozas and Odum
1987, Weller and Spatcher 1965) and diversity (Harris et al. 1983)
of aquatic animals than those with low interspersion. No
comparison data were found for cover interface, but diversity and
interspersion of plant species were observed during field sampling.
A variety of emergent species bordered the ponds and islands. In
many places, vegetation was stratified along the shorelines of
ponds, grading from more water tolerant species to less tolerant.
The U.S. Forest Service manages habitat for wildlife and plants
Echinochloa crusgalli on pond perimeters and among junipers in the
backwater areas of Redhead pond 6. The site has been operating for
more than 12 years; most plants are present due to natural
dispersal (M. Wilhelm, personal communication, U.S. Forest Service,
Lakeside, AZ), and a definite zonation of plant species and forms
has established.
Many small islands were built for nesting waterfowl at both
WTS studied. The area of islands at the Show Low site was 0.39 ha
(Table 22) . Because of evaporation and water drawdown, some of the
constructed islands were no longer surrounded by water, and they
were not considered islands in the CIS analysis. To estimate total
island area at high water, island boundaries were delineated
according to the change in plant communities on the photos. The
estimate obtained was 1.51 ha, with an average of 0.25 ha per pond
and a range of 0.15-0.39. This estimate, however, may be somewhat
low. Piest and Sowls (1985) reported an area of 1.14 ha for only
the Pintail Marsh, which was based on ground mapping.
Nevertheless, island area per pond at the Show Low site is within
the range of that reported for several non-WTS comparison wetlands
(Table 23).
Wetlands containing islands have been shown to support more
waterfowl than those without islands (Piest and Sowls 1985). The
density of nesting ducks is usually inversely correlated with
island size (Giroux 1981, Johnson et al. 1978). The six ponds
sampled at the Show Low site contain 37 islands, with an average
area of only 0.04 ha at high water. These conditipns have been
attractive to nesting waterfowl at the Show Low site. Most duck
63
-------
Table 23. Shoreline length per wetland area and island area for wetlands
in the Apache-Sitgreaves National Forest (Piest, personal
communication, Arizona Game and Fish Department, Phoenix, AZ).
Values given for this study are averages of the three ponds in
each marsh system at the Show Low site.
Site
Shoreline Length per
Wetland Area (m/hal
White Mountain Reservoir 38
Long Lake 39
Big Lake 49
Salt House Marsh 53
Mexican Hay Lake 72
Geneva Lake 75
Hog Wallow Lake 75
Sunrise Lake 76
Becker Lake 80
Atcheson Reservoir 88
Carnero Lake 92
Norton Reservoir 95
Crescent Lake 97
Little Mormon Lake 106
Reagan Reservoir 120
Nelson Reservoir 120
Luna Lake 143
Ellis Wiltbank Reservoir 159
Nutrioso Reservoir 170
St. Joseph Reservoir 174
Rudd Reservoir 178
Colter Reservoir 181
Basin Lake 185
Jessie Spring 192
Russel Reservoir 198
Marsh north of Mexican Hay Lake 207
Marsh northeast of Mexican Hay Lake 222
Pintail Marsh - this study 229
Marsh east of Pat Knoll 231
Marsh northwest of Hog Wallow 231
Marsh north of Hog Wallow 241
Hay Lake 243
First Marsh north of Pat Knoll 2(53
Dipping Vat Reservoir 265
Judd's Pond 271
Redhead Marsh - this study 204
East of Big Lake 287
Second Marsh north of Pat Knoll 292
Water Canyon Reservoir 300
Pool Corral Lake 388
Second Marsh northeast of White
Mountain Reservoir 400
Marsh west of Hog Wallow .500
Island Area
0.4
0.9
0.1
0.1
0.2
0.3
0.3
1.0
64
-------
nests found in the Pintail Marsh from 1980-1982 were on islands.
Nest success on islands was 93.5%, and in 1982 the breeding pair
density of waterfowl was 9.9/ha of water surface (Piest and Sowls
1985) .
The size of a wetland is vital to maintaining a marsh fauna.
To produce good waterfowl habitat, Belanger and Couture (1988)
recommend that artificial ponds be >0.5 ha. Both WTS studied meet
this criterion. However, large wetlands or complexes of wetland
and upland areas may be necessary for fulfilling all wildlife needs
or for attracting birds (Weller 1978). Because of the scarcity or
temporary nature of most natural wetlands in the arid and semi-arid
West, a large complex of wetland cells or ponds is an important
design aspect for WTS. In many areas of the arid West, WTS are
among the most dependable water sources. They are therefore likely
to attract more wildlife, and it is desirable that they meet all or
most habitat requirements of wetland-dependent wildlife. Both of
the western sites studied are relatively large systems that attract
many waterfowl and other water-dependent birds. Both also seem to
provide a good diversity and interspersion of habitat types for
meeting the varied requirements of wildlife.
Site morphology measurements such as shoreline length,
distance of vegetation edge, ratio of open water to vegetated area,
and island area are good indicators of habitat quality. Their
relationships to wildlife production and/or use have been
demonstrated. Site morphology measurements can be obtained from
maps or aerial photographs in a relatively short time and with less
effort than field work. They can be taken in every wetland of
interest, and replicate samples and assessment of variability are
not necessary. Some field ground truthing of vegetation types,
however, is necessary for aerial photo interpretation. Estimation
of dominant cover types can be obtained from photos while field
work might focus on obtaining a species richness. Aerial photos
and maps can also be used to evaluate the larger landscape setting,
which is of great importance in evaluating wildlife habitat,
particularly when the wetland in question is small. A wide variety
of information can be obtained from photos and maps, and their use
in the future is highly recommended.
One limitation of using landscape indicators is the high cost
of aerial photography. Current photos, if available, may be a
feasible alternative. The timing of aerial photography at western
sites is an important consideration because water levels are
variable. The most appropriate time frame for taking aerial photos
depends on the current water regime at the site and the indicators
and wildlife of most interest.
Water Quality
Water quality data for each site are presented in Table 24.
65
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Table 24. Summaries of water quality data at the Show Low arid
Incline Village sites. pH in standard units; Fee.
col.=total fecal coliform bacteria (# colonies/100 mL);
BOD=biochemical oxygen demand (mg/L); NH3-N=ammonia
" nitrogen (mg/L); TP=total phosphorus (mg/L) ; DO=dissolved
oxygen (mg/L); TKN=total Kjelclahl nitrogen (mg/L); LT=a
sample representing less treated water, collected near
the inflow end of the WTS; HT=a sample representing more
treated water, collected at the end of the WTS opposite
the inflow; P=Pintail pond 1; R=Redhead pond 6;
T=Telephone Lake; SD=standard deviation.
Variable
PH
pH
PH
BOD
BOD
BOD
Fee. col.
Fee. col.
Fee. col.
NH3-N
NH3-N
NH3-N
TKN
TKN
TKN
Location
P-LT
R-HT
T-LT
P-LT
R-HT
T-LT
P-LT
R-HT
T-LT
P-LT
R-HT
T-LT
P-LT
R-HT
T-LT
N
22
22
22
22
22
21
22
22
22
11
11
11
22
22
22
SHOW LOW
Ranae
5.9-8.8
8.3-9.9
8.0-9.5
5.0-51.0
3.0-38.0
0.9-20.0
0-1060
0-2040
0-1240
0.3-1.8
0.3-2.6
0.3-2.8
0.3-19.0
0.2-9.2
0.4-7.9
Mean
8.2
8.8
8.6
20.8
12.5
9.9
105
131
105
0.8
0.7
1.2
3.9
2.2
2.8
SD
0.6
0.4
0.4
12.0
10.4
5.2
234
452
310
0.5
0.7
0.9
4.4
2.2
1.6
INCLINE VILLAGE
Variable
BOD
BOD
NH3-N
NH3-N
TP
TP
DO
Location
LT
HT
LT
HT
LT
HT
LT
N
29
20
26
15
28
20
18
Range
3.0-20.0
1.0-18.0
0.2-18.0
0.1-0.3
0.1-6.4
0.1-1.5
2.5-6.0
Mean
8.5
6.5
3.0
0.2
2.7
0.3
4.5
SD
4.3
4.2
3.7
0.1
1.9
0.3
0.9
66
-------
The values reported for each water quality metric are intended to
characterize water quality at or near the inflow where water has
undergone less wetland treatment (LT) or near the opposite end of
the WTS where water has had the longest residence time in the WTS
and presumably is more highly treated (HT). At the point where LT
samples were taken at the Incline Village site, some water
treatment had already occurred because the water had passed through
the first and second cells.
The data are variable for most metrics, particularly fecal
coliforms. Means for all parameters measured at the Incline
Village site were lower in the HT samples than in LT samples,
indicating uptake within the WTS. Means for NH3-N and TKN at the
Show Low site were lower in the Redhead Marsh system (HT) than
those at the Pintail Marsh and Telephone Lake systems (LT). The
average BOD was lower in the Redhead Marsh than in the Pintail
Marsh. These patterns are expected because the Redhead Marsh
contains water with the longest residence time and degree
oftreatment. However, Telephone Lake had the lowest average BOD
concentrations at the Show Low site.
Means for the WTS are generally within the range of the
comparison wetlands for pH, total Kjeldahl nitrogen (TKN),. and
ammonia nitrogen (NH3-N) (Tables 25-27). Ammonia-nitrogen means
from Telephone Lake (1.2 mg/L) and the Incline Village LT (3.0
mg/L) samples were in the upper end of the range of values for non-
WTS, but HT means for ammonia-nitrogen from both WTS (0.7 mg/L at
the Show Low Redhead Marsh and 0.2 mg/L at the Incline Village
site) were in the middle or low range of values from non-WTS
(Tables 25 and 27) . .
Average biochemical oxygen demands (BOD) at Pintail pond 1
(20.8 mg/L) and Redhead pond 6 (12.5 mg/L) were higher than BOD of
comparison wetlands, although only three values were available from
non-WTS for comparison (Table 25). Average BOD concentrations at
the Incline Village site were low in comparison with those at the
Show Low site and were within the range of values for non-WTS
(Table 25).
Average dissolved oxygen (DO) at the Incline Village site (4.5
mg/L) was at the low end of the range of values reported for non-
WTS (2.0-14.3 mg/L) (Tables 26 and 27). However, DO was measured
only in water from the Incline Village treatment plant, before it
entered the wetland, so data from samples of more highly treated
water were not available for comparison.
Average total phosphorus in the Incline Village LT samples was
higher than the range of phosphorus for comparison wetlands (Tables
25 and 27), but the HT mean was at the lower end of the range,
indicating efficiency in phosphorus reduction within the WTS.
The above comparisons show that water quality means based on
67
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Table 26. Average pH and dissolved oxygen (DO) values from wetland
sites receiving irrigation drainage in west-central
Nevada, 1987-1989 (from Rowe et al. 1991). Range of the
means of pH from the Pintail and Redhead Marshes and
Telephone Lake are given for the Show Low site for
comparison; the DO mean given for the Incline Village
site is based on data collected at the inflow to the WTS
(DO data were unavailable from other points within the
WTS) . DO is in mg/L; pH is in standard units; sample
sizes in parentheses; NE=not evaluated.
Site Location
and Number • pH pp
Show Low site 8.2-8.8 (22) NE
(this study)
Incline Village site NE 4.5 (18)
(this study)
Carson Lake
14 8.3 (4) 10.0 (3)
15 8.1 (2) 8.1 (1)
Stillwater Wildlife
Management Area
26 8.6 (4) 7.0 (4)
28 8.9 (2) 8.4 (2)
31 9.4 (2) 2.0 (1)
36 8.8 (3) 14.3 (3)
37 8.8 (1) 9.7 (1)
38 9.0 (1) 9.2 (1)
39 9.4 (3) 11.4 (2)
40 8.9 (2) 8.3 (2)
41 9.0 (3) 12.7 (3)
42 9.3 (2) 2.4 (1)
Fernley Management Area
47 9.0 (6) 13.2 (6)
48 9.1 (1) 9.6 (1)
49 9.4 (5) 14.0 (5)
50 8.8 (3) 9.6 (3)
Humbolt Wildlife
Management Area
56 8.4 (4) 9.0 (3)
58 8.8 (3) 8.9 (2)
Reference Sites*
1 8.6 (4) 8.7 (4)
2 8.4 (5) 9.7 (5)
3 8.6 (3) 9.0 (3)
4 7.9 (6) 7.5 (5)
* not receiving irrigation drainage
69
-------
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HT samples and, in some cases, LT samples, from the two WTS are
generally within the range of values reported for non-WTS.
However, interpreting precisely what some water quality indicators
mean for assessing wildlife habitat quality is difficult because
the relationships between water quality and habitat quality is
indirect. Water quality influences community composition of
plants, invertebrates, and fish. These are more direct measures of
habitat quality and are better integrators of conditions important
to wildlife than is water quality. In addition, the influences of
water quality on habitat are not always consistent. Relationships
between nutrient concentrations and wildlife habitat quality often
are not applicable under a variety of environmental conditions.
In addition, water quality indicators are often variable, and
many measurements must be taken over time to accurately
characterize conditions on the site. In a monitoring program,
available resources and logistics may not permit the number of
measurements required. Use of existing data is also problematic.
In the arid West, WTS are often no-discharge systems; therefore,
site operators are not required to monitor water quality. Data are
often unavailable or discontinuous and cannot be relied on for
constructing data sets on which to conduct analyses. Data
management and record-keeping by site operators can vary, making it
potentially difficult to acquire specific data and to be certain
that all data have been obtained. The particular water quality
parameters measured differ from one site to another, which limits
the comparisons that can be made among sites and may affect
interpretation of results. Furthermore, proper evaluation of
acquired data requires review and evaluation of standard operating
and QA procedures used by field crews and analytical laboratories.
Interpretation and comparison of data can be difficult if methods,
collection frequencies, or intended uses of the data vary from one
site to another. For these reasons, the use of existing water
quality data sets is not recommended. However, sampling of some
water quality indicators, such as dissolved oxygen, ammonia, or
suspended solids, during a field effort might provide information
on system stressors. This information can be used to interpret
indicator data collected at the same time and to determine the
reasons for the status of a particular habitat indicator.
71
-------
CONCLUSIONS AND RECOMMENDATIONS
Wetlands that are used for treating wastewater also appear to
provide suitable wildlife habitat in the arid West. Wetland
treatment systems are an efficient reuse of water, eliminate some
of the chemical treatment, can be very cost-effective, and can be
beneficial to wildlife. Wildlife habitat is most often an
ancillary function of systems, and the wetlands vary greatly in the
habitat values that they provide. Much of the variation can be
attributed to whether wildlife habitat features are considered when
the wetlands are designed, funding available for incorporating
specific features (such as islands, wildlife food plants, irregular
shorelines, varying depths, and vegetation interspersion), and the
degree of management and monitoring of habitats once the wetland is
operating. ,
Table 28 contains a summary of the comparisons made between
the two WTS studied and non-WTS. Values for bird species richness
and density were above the range of values from non-WTS. Water
nutrient concentrations were generally within the range of
concentrations found in non-WTS, but their positions within the
range (high, middle, or low) varied. Land/water interface at the
Show Low site was in the middle to high range of values reported
for non-WTS.
None of the indicator values from the two WTS studied were
below the range of values for non-WTS. The available data suggest
that the two WTS studied provide wildlife habitat similar in
quality to that of non-WTS in the same region. Based on the higher
bird species richness and densities in the WTS, it appears thiat
birds prefer the two WTS over non-WTS in the vicinity. Because of
the scarcity of comparison data for vegetation and invertebrates,
however, it was not possible to base conclusions about wildlife
habitat on the majority of indicators evaluated. Furthermore,
habitat quality was assessed only in relation to comparison
wetlands, but little is known about the habitat quality of
comparison wetlands. Guidelines for selecting comparison, or
reference, wetlands with good wildlife habitat are needed.
A summary of the indicators used in this study, including
sampling effort, expense, reliability of information collected/
direct relevance to wildlife habitat quality, and recommendations
for development in future studies, is given in Table 29.
Vegetation, invertebrate, and site morphology indicators are
recommended for future development for evaluating wildlife habitat
quality in WTS. Birds may also be good indicators, but focus
should be on relating bird numbers to habitat quality or on
exploring indicators that may be more informative than bird numbers
for assessing habitat quality, such as bird feeding activity or
brood counts. It is important, particularly in the arid West, to
determine whether birds are present because the habitat is
preferable or because habitat, regardless of condition, is scarce.
72
-------
Table 28. General relationship of data from the WTS studied to the
range of values reported for non-WTS in the southwest
United States.
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industrial discharges, where user violations have occurred in the
past, or where other data collected indicate a potential problem
requiring further investigation).
The WET analysis proved difficult to use in WTS because of the
artificial nature and designated purpose of the wetlands. Many
ofthe questions were not designed to accommodate these systems and
thus were ambiguous and difficult to answer with certainty. The
majority of questions require a familiarity with the wetland
studied and with other wetlands in the surrounding landscape in
both the wet and dry seasons, and a scientist visiting the wetland
for only a short time may find it difficult to acquire enough
knowledge to answer many of the questions. Additional time or
alternatives for answering questions accurately (e.g., significant
contribution from site managers and other local scientists) would
be necessary if WET is used in the future.
Some topics regarding wildlife habitat quality (e.g., how to
measure it, how to evaluate it) require further study. The
following are suggestions for future studies:
• For comparing WTS with non-WTS, future studies should include
simultaneous sampling on nearby reference (non-WTS) wetlands,
if present, so that results from both types of wetlands are
more directly comparable and confounding factors can be
minimized. Aerial bird surveys at the Incline Village site
incorporated surveys at reference, non-WTS wetlands, and the
results were very revealing. Also, conclusions from such
comparisons can be drawn with more certainty than from
comparisons made using literature data. Comparison with
literature values might be sufficient for preliminary studies,
but to put in context the indicator values from WTS and to
make valid conclusions about the quality of wildlife habitat,
the best data for comparison are those that are collected at
the same time, in close proximity, on similar classes of
wetlands, and with the same sampling techniques.
Reference wetlands should be natural, enhanced, or restored
wetlands that are not used for wastewater treatment. Created
wetlands should not be used for comparisons because
insufficient research has been completed to show that they
duplicate wetland functions on a long-term basis (Kusler and
Kentula 1990). Establishing appropriate criteria for
selection of reference wetlands will require further thought.
One approach would be to establish guidelines for selecting
reference sites that represent "good" habitat quality.
Collected data can be used as a gauge against which
measurements or an aggregation of measurements taken at WTS
can be rated. Reference wetlands should also be as similar as
possible to the WTS in question with respect to size, wetland
classification, location, type of surrounding land use, and
degree of human disturbance. Comparisons should be
75
-------
quantitative. ,
In some landscapes, potential reference sites might all be in
marginal or poor condition. An alternative to reference site
comparisons would be to develop guidelines for rating habitat
quality. Guidelines should be performance standards that are
applied on the basis of best professional judgement and should
provide for flexibility for dealing with environmental
uncertainty (Chapman 1991).
Future work should also focus on developing means for
assessing and reducing data. Developing assessment methods
can identify potential stressors or causes of condition, which
can then be used to establish a gauge for rating habitat
value. Data reduction involves combining information from a
group of indicators or from multiple species to form a single
indicator, or index. For instance, species _ diversity
incorporates richness and abundance of all species into a
single value. A similar index might be developed for
vegetation structural diversity based on the number of
vegetation layers and their relative coverages. Multivariate
analyses are also useful for ansilyzing combined data and
forming indices. Species-specific data, however, can be used
to identify stressors or to monitor long-term changes at a
wetland.
The suite of indicators for this study was limited by level of
funding, labor, and logistical constraints. Future studies
should assess the usefulness of indicators that were not
examined in this study, particularly new metrics for
evaluating habitat in terms of vegetation, invertebrates, and
•site morphology. For example, invertebrate sampling should
include specific techniques for collecting benthic
invertebrates. It is recommended that new indicators be
directly related to wildlife habitat rather than those that
might only infer wildlife use through an indirect relation
(e.g., nutrients, sediment type, hydrology). Indirectly
related indicators might, however, be useful for identifying
ecosystem stressors and the reasons for the status of a
particular habitat indicator (e.g., hydrologic regime and
sediment types can influence the species composition of
plants). ;
If bird use is retained as an indicator in future studies, a
greater focus should be placed on bird activity (breeding,
feeding, roosting, and resting) and the presence of
threatened, endangered, or keystone species.
The elimination of some indicators, if other indicators
provide essentially the same information, would save money and
time in sampling and analysis. For instance, some vegetation
indicators, such as structural diversity, relative coverage of
76
-------
each structural type, can easily be obtained from aerial
photos. Aerial photo analysis might be more accurate,
particularly for large wetlands where time available restricts
thorough ground sampling of the whole wetland. More time
could be spent in the field sampling indicators, such as
species composition, abundance, and richness, which cannot be
obtained from photos.
This pilot study provided evidence that WTS provide wildlife
habitat and that the two WTS studied are used by a variety of
wildlife species. Wildlife habitat at both sites has been enhanced
while maintaining effective water treatment, which is evidence that
the two interests are compatible. A relatively dependable water
supply at both wetlands helps ensure the maintenance of wetland
habitat in an arid environment.
77
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86
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APPENDIX A. Site maps and sampling points
87
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Maps provided by site operators of the Show Low and Incline
Village sites are included in this appendix. The following
features are designated on each map: vegetation transect
locations, invertebrate sample points, bird survey points, and
water sampling points for whole effluent toxicity tests. Some of
the invertebrate samples were collected at a single spot in the
wetland, designated by an X on the maps. When invertebrate
densities were low, however, several net samples had to be
collected to obtain 0.5 hour of collection time. Therefore, X X
represents places where samples consisting of several nettings were
taken along a shoreline or the edge of vegetation from a single
habitat type.
The key below describes the symbols and features found on maps
in this appendix: I
Dikes
© Inflow sample collection point
-e- Outflow sample collection point
. . Vegetation transects
X or X X Invertebrate sample points
• (1) Bird survey points
88
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SHOW LOW WETLAND TREATMENT SYSTEM
Pintail
Marsh
N
(3B)
Redhead Marsh
-------
13
W
o
>
w
M
O
M
-------
APPENDIX B. Site contacts and local experts consulted
91
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SHOW LOW SITE
INCLINE VILLAGE SITE
Site Contacts
Mel Wilhelm
U.S. Forest Service
Lakeside Ranger District
RR3 Box B50
Lakeside, AZ 85929
Don Richey/Harvey Johnson
Incline Village General
Improvement District
893 Southwood Blvd.
P.O. Drawer P
Incline Village, NV 89451
Botanists consulted
Mel Wilhelm/Terry Myers
U.S. Forest Service
Lakeside Ranger District
RR3 Box B50
Lakeside, AZ 85929
Gail Durham
Range Conservationist
Soil Conservation Service
Office
Minden, NV 89423
Aerial Photography companies
Keeney Aerial Mapping
1130 W. Fillmore
Phoenix, AZ 85007
American Aerial Survey,
6249 Freeport Blvd.
Executive Airport
Sacramento, CA 95822
Inc.
Bird Surveyors
White Mountain Audubon Society
P.O. Box 3043
Pinetop, AZ 85935
and
White Mountain Land Surveys
P.O. Box 1478
Lakeside, AZ 85929
Rich Heap
Nevada Department of Wildlife
380 West B Street
Fallen, NV 89406
Water Analysis Laboratories
Western Technologies, Inc.
2400 East Huntington Drive
Flagstaff, AZ 86004
General Improvement District
893 Southwood Blvd.
Incline Village, NV 89451
92
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APPENDIX C. Invertebrate biologists and identification
keys used
93
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Biologists:
Nan Allen; Ann Hershey
221 Life Sciences Bldg. - Biology office
10 University Drive
University of Minnesota-Duluth
Duluth, MN 55812
Invertebrate taxonomic keys used:
Borror, D.J., C.A. Triplehorn, and N.F. Johnson. 1989. An
Introduction to the Study of Insects. Sixth Edition. Sanders
College Publishing, Philadelphia, PA.
Klemm, D.J. 1982. Leeches (Annelida:Hirudinea) of North America.
EPA-600/3-82/025. Environmental Protection Agency Environmental
Monitoring and Support Lab. Office of Research and Development,
Cincinatti, OH.
Merritt, R.W. and K.W. Cummins. 1984. An Introduction to the
Aquatic Insects of North America. Second Edition. Kendall Hunt
Publishing Company, Dubuque, IA.
Pennak, R.W. 1978. Freshwater Invertebrates of the United States.
Second Edition. John Wiley and Sons, Inc., New York, NY
Pennak, R.W. 1989. Freshwater Invertebrates of the United States.
Third Edition. John Wiley and Sons, Inc., New York, NY.
Usinger, R.L. (ed.). 1968. Aquatic Insects of California, with
North American Genera and California Species. University of
California Press, Berkeley, CA.
Ward, H.B. and G.C. Whipple (eds.). 1959. Fresh Water Biology.
Second Edition. John Wiley and Sons, Inc., New York, NY.
Wiederholm, T. (ed.). 1983. Chironomidae of the Holarctic Region.
Part 1 Larvae. Entomologica Scandiriavica Supplement No. 19.
Borgstroms Tyckeri AB, Motala.
94
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APPENDIX D. Water chemistry of replicates used for whole
effluent toxicity tests.
95
-------
Ceriodaphnia dubia Chronic Test
Sample
Show Low site
Inflow
Outflow
Control
Inflow
Outflow
Control
Mean
PH .
9.46
9.33
8.20
8.44
8.69
8.05
pH
Range
Mean
Temp
f°C)
Initial Chemistries
9.31-9.58
9.24-9.41
8.14-8.24
26.1
26.0
26.7
Final Chemistries
8.41-8.50
8.58-8.76
7.99-8.14
25.9
26.0
26.2
Mean
DO*
fma/L)
7.3
7.4
7.8
7.7
7.7
7.7
Mean
Conductiv.
fumhos/cm)
806
1036
122
Incline Village site
Inflow
Outflow
Control
Inflow
Outflow
Control
7.20
9.61
8.20
7.90
8.18
8.17
Initial Chemistries
7.04-7.36
9.26-9.96
8.18-8.23
26.2
26.1
26.9
Final Chemistries
7.82-7.95
8.16-8.20
8.03-8.30
25.9
25.9
26.2
7.8
8.1
7.9
7.2
7.6
7.3
1214
4077
127
*DO=dissolved oxygen
—=not measured
96
-------
Appendix D, continued.
Fathead Minnow Acute Tests
Sample
Show Low site
Inflow
Outflow
Control
Inflow
Outflow
Control
Mean
PH
9.53
9.37
8.18
8.21
8.50
7.95
Mean
Temp
f°C]
PH
Range
Initial Chemistries
9.48-9.58
9.33-9.41
8.14-8.22
26.1
26.0
26.7
Final Chemistries
25.8
26.1
25.9
Mean
DO*
fmg/L)
7.4
7.1
7.9
7.0
6.8
7.2
Mean
Conductiv.
(umhos/citO
814
1036
117
Incline Village site
Inflow
Outflow
Control
Inflow
Outflow
Control
Initial Chemistries
7.11 7.04-7.19 25.7 8.0
9.77 9.58-9.96 25.4 8.2
8.19 8.18-8.20 26.8 7.9
Final Chemistries
7.78 — 25.7 7.7
8.05 — 25.9 7.7
7.91 — 25.7 7.5
1249
4395
144
*DO=dissolved oxygen
—=not measured
97
-------
APPENDIX E. Detailed bird survey data
98
-------
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Appendix E, continued.
Species detected but not counted (recorded only as present) and the
number of surveys on which they were seen, Show Low site, 1991.
Species # of Surveys - '
turkey vulture 16
sharp-shinned hawk 1
Cooper's hawk 5
red-tailed hawk 3
bald eagle 3
northern harrier 4
osprey 4
peregrine falcon 5
American kestrel 12
Forster's tern 1
black tern 1
mourning dove 23
common nighthawk 3
black-chinned hummingbird 1
broad-tailed hummingbird 14
rufous hummingbird 3
belted kingfisher 2
northern red-shafted flicker 5
red-naped sapsucker 1
western kingbird 6
Cassin's kingbird 4
ash-throated flycatcher 3
black phoebe 23
Say's phoebe 17
willow flycatcher 1
dusky flycatcher 1
western wood peewee 7
horned lark 1
American pipit 1
tree swallow 15
violet-green swallow 20
northern rough-winged swallow 5
bank swallow 4
cliff swallow 2
barn swallow 22
purple martin 6
scrub jay 19
pinyon jay 5 ,
common raven 17
American crow 5
plain titmouse 3
bushtit 2
101
-------
Appendix E, continued.
Species detected but not counted (recorded only as present) and the
number of surveys on which they were seen, Show Low site, 1991.
Species
# of Surveys
Bewick's wren 1
northern mockingbird 2
American robin 10
western bluebird 5
mountain bluebird 4
Townsend's solitaire . 3
blue-gray gnatcatcher 2
ruby-crowned kinglet 7
phainopepla 1
loggerhead shrike 5
orange-crowned warbler 2
Virginia's warbler 1
yellow warbler 6
yellow-rumped warbler 11
black-throated gray warbler 3
MacGillivray's warbler 3
Wilson's warbler 5
western meadowlark 20
yellow-headed blackbird 23
red-winged blackbird 26
northern oriole 1
Brewer's blackbird 3
great-tailed grackle 6
brown-headed cowbird 3
western tanager 2
black-headed grosbeak 1
Lazuli bunting 4
house finch 2
pine siskin 2
lesser goldfinch 10
green-tailed towhee 2
rufous-sided towhee 1
dark-eyed junco 3
vesper sparrow 1
lark sparrow 8
American tree sparrow 1
chipping sparrow 19
Brewer's sparrow 3
white-crowned sparrow 5
Lincoln's sparrow 1
song sparrow 3
102
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Appendix E, continued.
Maximum.number of birds of each species counted on a single survey,
April through November, 1991, at the constructed and natural marsh
systems - Incline Village site. The number of surveys (of the 18
total) on which each species was detected is indicated in
parentheses.
_-*khta*MjB
Species
eared grebe
western grebe
pied-billed grebe
American white pelican
cattle egret
snowy egret
tundra swan
Canada goose
white-fronted goose
mallard
gadwall
Northern pintail
green-winged teal
blue-winged teal
cinnamon teal
American widgeon
Northern shoveler
redhead
ring^-necked duck
canvasback
scaup
common goldeneye
bufflehead
ruddy duck
other duck
red-tailed hawk
golden eagle
bald eagle
northern harrier
American kestrel
sora
common moorhen
American coot
semipalmated plover
killdeer
common snipe
long-billed curlew
sandpiper spp.
willet
Constructed Wetland
97 (10)
1(1)
7 ( 3)
30 ( 2)
1(2)
1 ( 1)
14 ( 1)
231 (14)
18 ( 1)
177 (17)
254 (15)
266 (17)
40 ( 6)
10 ( 6)
785 (15)
294 (16)
110 (13)
74 (16)
8 ( 2)
1 ( 2)
17 ( 4)
11 (1)
22 ( 5)
98 (15)
10 ( 1)
2(2)
1(2)
( 1)
1
1
1
4 (13)
4 ( 2)
( 2)
( 1)
1235 (18)
2 ( 1)
31 (11)
1 ( 1)
2 ( 4)
1 ( 1)
10 (12)
Natural Wetland
0
0
0
0
0
1 ( 1)
0
44 ( 3)
0
155 ( 8)
139 ( 5)
34 ( 4)
0
2 (1)
147 ( 6)
23 ( 5)
10 ( 5)
13 (3)
0
0
0
0
0
9 ( 1)
0
1 ( 1)
o •
0
4 ( 7)
1 CD
0
0
81 ( 6)
0
2 ( 2)
0
0
0
0
103
-------
Appendix E, continued.
Maximum number of birds of each species counted on a single survey,
April through November, 1991, at the constructed and natural marsh
systems - Incline Village site. The number of surveys (of the 18
total) on which each species was detected is indicated in
parentheses.
greater yellowlegs 5(1) 0
long-billed dowitcher 40 ( 1) 0
marbled godwit 0 1(1)
American avocet 48 (13) 0
black-necked stilt 72 (13) 10 ( 4)
phalarope spp. 265 ( 7) 0
California gull 11 ( 8) 0
Forster's tern 0 4(1),
black tern 0 2(1)
common raven 6(1) 0
'
104
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