^as**ซ !
' 4% \ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
\jyjfe | WASHINGTON, D.C. 20460
APR I 8 1996
OFFICE OF
WATER
Dear Colleagues:
The U. S. Environmental Protection Agency is pleased to transmit a copy of the document
entitled Combined Sewer Overflows and the Muliimetric Evaluation of Their Biological
Effects: Case Studies in Ohio and New York. This document reports on a project undertaken
to measure the biological effects of combined sewer overflows (CSOs). CSOs are discharges
to surface waters of mixtures of untreated domestic sewage, industrial and commercial
wastewaters, and stormwater runoff. Concern has grown in recent years over the possible
adverse ecological effects of CSOs. This concern was reflected in the 1994 CSO Control
Policy, which identified the need for characterization of impacts on aquatic life and designated
uses. , . ' ._.-; . ....-..'. : ,
Aquatic biological communities are exposed to many environmental stressors, which may
include point and nonpoint source pollution and habitat alteration or destruction. How the
biological communities respond to and integrate these impacts are often difficult to interpret.
However, biological assessment methods exist which are designed to evaluate and characterize
biological integrity and to identify possible causes of the biological impacts. One of these is
an EPA method known as rapid bioassessment protocols (RBPs). RBPs include standardized
procedures to assess the biological status arid habitat condition of streams, hi comparison with
minimally impacted streams of the same type. The biological assessment calculates multiple
statistics (known as metrics) measuring different attributes of the aquatic community, such as
species diversity, food chain relationships, and pollution sensitivity. The metrics are
combined into one score of the overall biological status of the community. Interpretation of
individual metrics may provide clues to causes of any impairment. Habitat assessments are
conducted to determine if habitat degradation is a cause of biological impairment, alone or in
combination with water quality problems. It consists of standardized methods to evaluate
stream and riparian features important to healthy aquatic communities.
These case studies were carried out in Ohio and New York, both of which have well-
established biological monitoring and assessment programs and which use methods similar in
approach to RBPs. The availability of historic data allowed comparison of results between
studies. The report also explores whether different levels of effort within the RBP framework
affected the results. The purpose of this was to. determine if using smaller sample sizes or a
lower level of detail in organism identification would be sufficient for some purposes such as
screening studies and establishing priorities: A final objective was to address possible
applications of the RBP methodology in other aspects of watershed protection.
Recycled/Recyclable . Printed with Vegetable Oil Based Inks on 100% Recycled Paper (40% Postconsumer)
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This document should not be construed as Agency guidance or policy, or as a requirement to
use the RBP methodology. Rather, the intention of this document is to provide utformation
on potential applications of RBPs and biological assessments. The document is aimed at state
and local biologists and managers looking for potential tools to assess the biological effects of
CSOs. It can be a tool to help prioritize limited resources where the CSO impacts are the
greatest and where controls would do the most good.
Applications of RBPs are not limited to CSOs, however. Biological assessments have useful
applications in various watershed protection approaches such as the TMDL process, 305(b)
reporting, stormwater monitoring, and development of biological criteria^ Bioassessments are
useful screen tools for identifying and prioritization impaired waters. They may be able to
provide an indication of causal relationships for different types of impairment such as habitat
degradation, toxic loading, and organic enrichment. Finally, they may be useful in assessing
how effective pollution control measures are in protecting aquatic life and biological integrity.
Requests for additional copies should be sent to U.S. Environmental Protection Agency,
National Center for Environmental Publication and Information, 11029 Kenwood Road,
Building 5, Cincinnati, Ohio 45242 (513-489-8190), or by email . - _
(Waterpubs@epamail.epa.gov.). Please refer to the EPA document number (EPA 823-R-96-
002). For more information call Marjorie Coombs at 202-260-9821 (or via the Internet:
coombs.marjorie@epamail.epa.gov).
We appreciate your interest in biological assessment and watershed management,
Tudor T. Davies, Director
Office of Science and Technology
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United States Off ice of Water EPA-823-R-96-002
Environmental Protection Washington, DC 20460 April 1996
Agency
svEPA Combined Sewer
Overflows and the
Multimetric Evaluation of
Their Biological Effects:
Case Studies in Ohio and
New York
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Combined Sewer
Overflows and the IMuItimetric Evaluation
of Their Biological Effects: Case Studies in
Ohio and New York
United States Environmental Protection Agency
Office of Water
Washington, DC 20460
EPA-823-R-96-002
, April 1996
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Contents
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1.1 Document Purpose ...;..... j 1
1.2 Environmental Effects of CSOs .....^ ...1
1.3 Biological Assessments J .......2
1.4 Reference Conditions .....;. ป 3
2.1 Habitat Quality Assessment ..5
2.2 Benthic Macroinvertebrate Sampling .> .........5
2.2.1 Sampling and Sample Handling 5
2.2.2 Taxonomy i...: .. >. ....7
2.2.3 Counting -.8
2.3 Data Analysis 8
2.3.1 Development of Bioassessment Scoring Criteria :..- : 8
2.3.2 Metrics ......... ........ .'.... 8
2.4 Quality Assurance/Quality Control..; 10
Evaluating the Biological Effects of Combined Sewer Overflows in Ohio ......ซ~.......~.ป......................~.......~... 11
3.1 Site Selection and Location Description 11
3.2 ResultsTaxonomy and MetricsThe Scioto River at Columbus, Ohio 11
3.2.2 The Scioto River at Columbus, Ohio , .'. 11
3.2.2.1 Historical Information : .15
3.2.2.2 Sampling Station Descriptions and Habitat Quality Assessments 15
3.2.2.3 Biological Assessments 17
3.2.2.4 Comparison to Historical Assessments ..., 18
3.2.3 The Sandusky River at Bucyrus, Ohio 19
3.2.3.1 Historical Information , ; - 19
3.2.3.2 Sampling Station Descriptions and Habitat Quality Assessments 19
3.2.3.3 Biological Assessments :. 23
,3.2.3.4 Comparison to Historical Assessments ; 23
3.2.4 The Little Cuyahoga River at Akron, Ohio ; ซ 23
3.2.4.1 Historical Information ." 24
3.2.4.2 Sampling Station Description and Habitat Quality Assessments 25
3.2.4.3 Biological Assessments 27
3.2.4.4 Comparison to Historical Assessments 28
Evaluating The Biological Effects of Combined Sewer Overflows in New York.; ... .. 31
4.1 Site Selection and Location Description :.. 31
4.2 Results ซ.ซ... - 31
4.2.1 .Taxonomy and Metrics 31
4.2.2 Canastota Creek at Canastota, New York 33
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4.2.2.1 Historical Information .... ...... > ...... ซ.ซ. ........... ....... ...... .................. ........ ป .......... 33
4.2.2.2 Sampling Station Description and Habitat Quality ......... . ..... . ............ ซ ......................... 34
4.2.2.3 Biological Assessments ... [[[ ........................................... ฐ3^
4.2.3 Harbor Brook in Syracuse, New York.. ............................................ ....... .....'...ป...- ......... -37
4.2.3.1 Historical Information ................................... ................... ; ................ : ............................ 37-
4.2.3.2 Sampling Station Description and Habitat Quality Assessments ...... . ............................. 38
4.2.3.3 Biological Assessments ............... . ......................................... ............ ........ .................... ^0
4.2.4 Onondaga Creek in Syracuse, New York ...................................... ...... ..... ................ 41
4.2.4.1 Historical Information ............ .... ................................ - ..... - .............. ............................. *1
4.2.4.2 Sampling Station Descriptions and Habitat Quality .......................... .,., ............ .............. 41
4.2.4.3 Biological Assessments .................................................. ........... - ....... ............................. *3
...~...ซ.... ..ป""""""""""
Evaluation of Method Variation ................ .ป. - -
5.1 Adequacy of Screening Level (Rapid Bioassessment Protocol I) ...... . ............ ....... . ....... , ............ 45
5.2 Metric Performance with Variable Methods..... ............ . ........... ........................ .......................... ^5
5.2.1 Taxonomic Level Effects on Metric Performance ............. : ....... . ....... . ............. ............... 47
5.2.2 Subsampling Level Effects on Metric Performance ..................... ....ป ............... ........... -51
5.3 Summary of Results ... ........ . .......................... ....... ................................. ......... ........................... " 5
~......~.......~...ซปซ"ซ""""""ป"""~"""-""'""""""*"'""
6.1 Historical Assessment Comparisons ... ......... ........ ........................................ ....... . ............... ...... ฐ*
6.2 Statistical Comparisons .................................... ................................... ......... '' .......... ซป ......
6.2.1 Taxonomic Level Conclusions ._ ..................................... ................. ........................... -^
6.2.2 Subsample Size Conclusions ............ . .......................... ................ ......... ; .................... ฎ*
6.3 Usefulness of RBPs in Assessing CSO Biotic Effects . ..... . ........ . ..................... ..... ..... ........ ........ ฐ2
6.4 The Place of Bioassessment in Watershed Protection ........... . .......................... ..... ......... ........... 63
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Figures
2-1 Habitat assessment field sheets;.riffle/run prevalence.
3-1 State of Ohio; three river systems within which the CSO study occurred.
3-2 Cities of Columbus and Circleville, Ohio.
3-3, Linear comparison with Ohio EPA assessments on the Scioto River.
3-4 Percent Comparability of Biota and Habitat with Reference Conditions.
3-5 Cities of Bucyrus and Melmore, Ohio.
3-6 Linear comparison with Ohio EPA assessments on the Sandusky River.
3-7 City of Akron, Ohio. .
3-8 Linear comparison with Ohio EPA assessments on die Little Cuyahoga River.
f' - ! '
4-1 State of New York:
4-2 Locations of sampling stations on Canastota Creek.
4-3 Locations of sampling stations on Onondaga Creek, Harbor Brook, and Furnace Brook.
4-4 Location of sampling station on the Tioughnioga River (West Branch).
5-1 Correlational scatterplot (1:1) of bioassessment score, family vs^ genus/species level taxonomy
5-2 Correlational scatterplot (1:1) of taxa richness, family vs. genus/species level taxonomy.
5-3 Correlational scatterplot (1:1) of Hilsenhoff Biotic Index, family vs. genus/species level taxonomy.
5-4 Correlational scatterplot (1:1) of percent contribution of dominant taxon, family vs. genus/species level taxonomy.
5-5 Correlational scatterplot (1:1) of Pinkham-Pearson Community Similarity Index, family vs. genus/species level
taxonomy.
5-6 Correlational scatterplot (1:1) of bioassessment score, 100 vs. 300 organism subsample.
5-7 Correlational scatterplot (1:1) of taxa richness, 100 vs. 300 organism subsample.
5-8 Correlational scatterplot (1:1) of scraper/(scraper + filterer collector), 100 vs. 300 organism subsample.
5-9 Correlational scatterplot (1:1) of no. shredders/total sample, 100 vs. 300 organism subsample.
in ป
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Tables
3-1 Biological sampling stations located in Ohio.
3-2 Scoring criteria developed for the benthic macroinvertebrate assemblage on each Ohio study river using USEPA's
rapid bioassessment protocols.
3-3 Habitat assessments and physicochemical measurements of the Scioto River taken on 8 September 1992.
3-4 Calculated biological metrics based on 300-organism subsamples from double-composite 1-m2 kicknet samples.
3-5 Habitat assessments and physicochemical measurements of the Sandusky River taken on 9 September 1992.
3-6' Habitat assessments and physicochemical measurements of the Little Cuyahoga River taken on 24 September
' 1992. : ; , ' .. ..'., - ./ -.-.,
4-1 Biological sampling stations located in or near Syracuse, New York.
4-2 Scoring criteria developed for the benthic macroinvertebrate assemblage using RBPs in New York.
4-3 Metric values calculated from 300-organism subsamples.
4-4 Primary taxonomic composition of benthic macroinvertebrate samples taken by Preddice.
4-5 Canastota Creek habitat assessment scores. ' . >
4-6 Harbor Brook habitat assessment scores.
4-7 Onondaga Creek habitat assessment scores.
5-1 Narrative screening-level assessments of ten study stations in New York State.
5-2 Comparison of biological assessments between RBPI and RBPin.
5-3 Family-level metric values calculated from 100-organism subsamples.
5-4 Genus/species level metric values calculated from 100-organism subsamples. .
5-5 Significance of comparisons between taxonomic treatments of 100-organism subsamples at ten sampling stations
in New York. , .
5-6 Significance of comparisons between treatments of samples from ten stations in New York.
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Acknowledgments
heprimary authors of this document (James B.
Stribling and Christiana Gerardi, Tetra Tech, Inc., _
and Marjorie Coombs, U.S. Environmental Protection
Agency/Office of Science and Technology) would like to
thank a number of persons who have been involved in
various aspects of this project. For project planning arid
review, contract administration, and field assistance in
Ohio, we greatly appreciate Chris Faulkner's (USEPA/
OWOW) efforts. For field and logistical assistance and
historical information in Ohio, we would like to thank
Allen Burton and Kathy Jacher (Wright State University,
Dayton, Ohio) and Jeff DeShon and Chris Yoder (Ohio
EPA, Columbus, Ohio). For the same assistance in New
York, we thank Scott Cook, Lee Flocke, Bob Bode, and
Margaret Novak, all of the New York Department of
Environmental Conservation. Also, from NYDEC (Special
Licenses), we thank Chris VonSchilgen for expediting our
application for a collection permit. For assistance in
fieldwork, graphical and editorial activities, and technical
review, we acknowledge Michael Barbour, Jeroen
Gerritsen, Michael Bowman, Steve Lipham, Catherine
Deli, and Linda Shook, all of Tetra Tech, Owings Mills,
Maryland, and Martha Martin and Robert Johnson of Tetra
Tech, Fairfax, Virginia. Taxonomic work for both Ohio
and New York samples was performed by B. Kuklinska and
M. Swift, Monticello Ecological Research Station, Univer-
sity of Minnesota, Monticello, Minnesota. The following
provided review and comments on drafts of the report:
Jeffrey E. DeShon, Ohio Environmental Protection Agency,
Monitoring and Assessment Section; Margaret A. Novak ,
and Robert Bode, New York Department of Environmental
Conservation; Wayne S. Davis, U.S. Environmental
Protection Agency, Office of Policy, Planning, and Evalua-
tion; Jim Green and Chuck Kanetsky, U.S. Environmental
Protection Agency, Region HI; Troy Hill, U.S. Environ-
mental Protection Agency, Region VI; and Carol Winston,
SAIC. This project was supported by USEPA/OWOW/
AWPD Contract Nbs. 68-C9-0013 and 68-C3-0303 and
USEPA/OST/SASD Contract Number 68-C3-0374 to Tetra
Tech, Inc. ,
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Executive Summary
Combined sewer overflows (CSOs) are direct dis-
charges into wetlands, lakes, coastal waters, streams,
and rivers of untreated domestic, commercial, and indus-
trial waste and wastewaters, and urban storm water runoff.
They have recently received increased national attention
because they are recognized as a primary contributor to
water quality degradation in some urban areas, as identified
by the President's Clean Water Initiative.
CSOs may have deleterious effects both on the designated
recreational uses because of the pathogens found in raw
sewage, and on the designated aquatic life uses because of
adverse impacts on the biological community. These case
5 studies were initiated to examine the effects of CSOs on the
biological integrity of some example streams, using an i
established EPA protocol for biological assessment.
These projects focused upon several objectives:
1. Evaluation pf the effectiveness of rapid bioassess-
ment protocols (RBPs) for detecting biological
responses to combined sewer overflows; .
2. Comparison with historical assessments performed
by the Ohio Environmental Protection Agency and
the New York Department of Environmental
' Conservation;
3. Comparison of results from different levels of
assessment rigor, in particular, of taxonomic
identification level and subsample size; and
4. Evaluation of the potential application of bio-
assessment methods to the'Total Maximum Daily
Load (TMDL) process and other watershed
protection approaches.
These case studies are intended for use by state bioassess-
ment personnel, CSO management and control staff, and
regional watershed protection coordinators. However* this
document should not be construed as Agency guidance or
policy, or as a requirement to use the RBP methodology in
any given situation.
RBPs were applied at a total of 23 sampling stations in 10
streams and rivers in Ohio and New York., In Ohio, a
subsample (300 organisms) was taken from each of 11
benthic macroinvertebrate samples; in New York, two
subsamples (100 organisms and 200 organisms) were taken
from each of 12 samples.
RBPs include a procedure to assess habitat quality, which
was employed at each location. The procedure evaluates
stream and riparian habitat features important to healthy
aquatic communities such as channel width, depth, and
sinuosity; instream cover (variety of substrate sizes, woody
debris); riparian vegetation and canopy cover; and bank
stability. Habitat assessments are conducted in order to
determine if habitat degradation is a limiting factor for
aquatic communities in the absence of, or in addition to,
water quality problems. ,
RBPs also include an assessment of biological condition,
which is based on an aggregation of several metrics
calculated from the sampling results. These metrics are
attributes of the community of aquatic organisms being
sampled and are used to characterize the status of a stream.
When compared with reference values, the aggregated
metrics are an indicator of ecological condition. The
metrics used in these studies include: taxa richness;
Hilsenhoff Biotic Index (HBI); ratio of scrapers to filterer
collectors; ratio of Ephemeroptera, Plecoptera, and
Trichoptera (EPT) to Chirononu'dae; percent contribution
of dominant taxon; EPT index; percent shredders; ratio of
Hydropsychidae to total Trichoptera; Pinkham-Pearson
Community Similarity Index; Quantitative Similarity Index
(QSI)-Taxa; Dominants-In-Common (DIC)-5; and QSI-
Functional Feeding Group (FFG).
.. RBPs were found to be useful hi determining biological
impairment due to CSOs and additional urban effects.
Adverse biological responses to CSOs were identified at all
stations downstream from CSO input. Responses included
increased abundance of Chironomidae, increased abun-
dance of filterer collectors, decreases in taxa richness, and
an increase in HBI values. All of these biological re-
sponses indicate a shift from a well balanced community
structure to one of increased tolerance of pollution. The
responses are characteristic of nutrient and/or toxic loading.
Study areas in Ohio were selected based on the availability
of data from previous biological assessments conducted by
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the Ohio Environmental Protection Agency (Ohio EPA) on
rivers and streams impacted by CSOs. The three areas
selected were the Scioto River at Columbus, the Sandusky
River at Bucyrus, and the Little Cuyahoga River at Akron.
The Scioto River is a major tributary of the southern Ohio
River and has a long history of degradation from a variety
of sources including upstream water withdrawals, channel
modifications, urban runoff, and input of organic matter,
nutrients and toxics from CSOs. Historical monitoring by
the Ohio EPA has generally resulted in biological assess-
ment ratings as "poor" or "fair" in the Scioto near Colum-
bus; assessment results from this study are consistent with
the historical data. Habitat conditions at each station were
judged to be similar so that any biological differences
between stations should be due to water quality effects.
The two stations within the zone of CSO influence were
found to exhibit "moderate" and "slight" impairment
relative to the regional reference station. Examination of
the individual metrics indicate that the impairment may be
due to organic enrichment and an increase in suspended
organic particulates. The upstream reference station was
found to have slight impairment relative to the regional >
reference. Review of individual metrics for the upstream
station indicate that impairment was likely due to develop-
ment, road runoff, and other human perturbations occurring
upstream and adjacent to this station.
The Sandusky River is a major tributary to Lake Erie which
runs through predominantly agricultural land in north central
Ohio. Historical biological assessments of the Sandusky
River at Bucyrus revealed significant impacts to the fish, and
macroinvertebrate communities from CSOs and the Bucyrus
wastewater treatment plant (WWTP). In 1990, upgrades to
the WWTP were made and corresponding improvements were
reported in the.biological condition. However, further
historical assessments as well as current assessments indicate
that slight impairment of the macroinvertebrate community
remains downstream of CSO inputs. Impairment appears to
be due to a combination of habitat degradation and water
quality impacts associated with CSOs.
The Little Cuyahoga River flows through Akron in
northeastern Ohio. The study area begins downstream of
the Mogadore Reservoir. Historical assessments conducted
by Ohio EPA indicate "fak" and "poor" biotic conditions
due to a combination of urban runoff and organic enrich-
ment problems from lake and wedand drainage. Current
biological assessments indicate that die Little Cuyahoga
has moderate biological impairment at the farthest down-
stream station; the upstream station was also assessed as
having biological degradation. Habitat conditions were
somewhat degraded at all stations along the Little
Cuyahoga but were comparable at all three sites. Biologi-
cal impairments at the downstream stations can thus be
attributed to water quality. There was a distinct depression
in overall biological condition at farthest downstream
station, including decreased abundance and low diversity.
This may possibly indicate the presence of toxicants
contributed by CSO and/or industrial inputs. The middle
station was originally expected to have been impacted by
CSOs; however, the study results indicate improved.
conditions over the historical assessments. Further
investigations revealed that the CSO outfalls upstream oiF
the middle station had been recently eliminated. The biotic
improvement over time shown at this station reflected their
removal.
Three streams were also selected for the New York case
study, Canastota Creek, Harbor Brook, and Onondaga
Creek. These streams were selected by New York Depart-
ment of Environmental Conservation for their known CSO-'
inputs and relevant historical assessment information.
Historical assessments of Canastota Creek indicate inputs
of toxics as well as organic enrichment. Recent assess-
ments (1990) indicate moderate impacts to the
macroinvertebrate community in Canastota Creek. The
current study found that the upstream station and the firs;t
CSO station were slighdy to moderately impaired, likely
due hi part to organic enrichment occurring upstream of
any CSO impacts. The downstream station was moderately
impaired. Although the biological assessment score of the
middle station was similar to that of the upstream station,
examination of individual metrics found that the middle
and downstream stations had a higher proportion of -
individual organisms considered to be pollution-tolerant,
which is probably a response to CSO influence.
Habitat assessments on Harbor Brook indicated moderate
impacts and severe impacts at-the upstream and middle
stations, respectively, as demonstrated by poor species
richness and the high abundance of tolerant taxa. The
results of the current study are consistent with these
historical findings. Habitat conditions at the middle and
downstream stations were very poor and the station farthest
downstream on Harbor Brook was unsible to be sampled
due to severe habitat alterations (channelization), deep slow
moving water, and a very soft bottom. The screening level
assessment conducted at this site indicated severe biologi-
cal impairment. Both the middle and downstream stations
contained taxa considered to be tolerant to pollution and
habitat degradation.
Historical assessments on Onondaga Creek correspond well
to assessments conducted at the downstream station of the
current study; both assessments indicated moderate to
moderately-severe impairment. The upstream and middle
stations on Onondaga Creek were found to be moderately
impaired likely due to organic enrichment and habitat
degradation.
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The effectiveness of RBPs for detecting biological re-
sponses to CSOs was demonstrated through these case
studies. Although "cause-and-effect" relationships are
complicated by other problems associated with urbaniza-
tion, such as habitat degradation and potential industrial
discharges, reasonable support for attributing biological
impairment to CSO effects was possible. Impairment due
to CSO outfalls was noted in biological data in the histori-
cal assessments conducted by Ohio EPA and NYDEC, as
well as in the current studies for all of the streams assessed.
The upstream stations in the Scioto River, the Little
Cuyahoga River, Canastota Creek, and Harbor Brook were
all located in urbanized areas, yet the biological communi- ,
ties were of a high enough quality in comparison with the
downstream stations to indicate that CSO outfalls had
adverse effects on the macroinvertebrate communities.
Comparisons between the current studies and historical
biological assessment results proved tb.be valuable;
consistent comparisons were made with most historical
assessments. In one instance where there were differences
between historical and current results, i.e., the Little
Cuyahoga River, the improvement in the biological
assessment appears to be die result of removal of the CSO
outfalls in that section of the river. Different sampling
gears were used between the current and historical studies,
therefore, only overall assessment results could be com-
pared. Evaluation of how individual metrics or actual
quantitative data differed among asessments was not
possible. .
Comparisons of individual metric values between different
taxonomic levels showed some variability; however, total
bioassessment scores (comparative ranking of sites)
showed no difference. The appropriate level of taxonomic
identification for a study is based on the study objectives;
for other than screening-level assessments, the lowest
possible level of identification is suggested. Several
metrics use functional feeding group and tolerance value
designations for their calculation (scraper-filterer collector
ratio, percent shredders, QSI-FFG, and HBI). These are
based on the knowledge of the ecology of macroinverte-
brates at the species level. Therefore the uncertainty
associated with the assignment of functional feeding group
-and tolerance value is greater the less detailed the identifi-
cation is (e.g., genus, family, or order as opposedto
species).
Subsample size had little effect on the rank order of total
bioassessment scores. Metrics based on some form of taxa
richness were variable with different subsample sizes, as
expected, due to the increased probability of rare taxa being
included in the larger subsample. However, as long as the
test site and reference sites are treated in the same manner
(i.e., same subsample size and taxonomic level), the
biological assessment will be valid. Subsamples of 100
organisms are recommended in New York when using .
multimetric assessment approaches.
Biological assessments have useful applications in various
watershed protection approaches such as the TMDL
process, 305(b) reporting, stormwater monitoring, and
development of biological criteria. Bioassessments are
useful screening tools for identifying and prioritizing
impaired waters. They may be able to provide an indica-
tion of causal relationships for different types of impair-
ment such as habitat degradation, toxic loading and organic
enrichment. Finally, they are useful in assessing how
effective pollution control measures are in protecting
aquatic life and biological integrity.
A limitation of this study is that, in nearly all cases, the
farthest upstream stations showed some kind of impair-
ment Using impaired upstream stations as the control will
often cause the downstream "affected" stations to appear
better than:they actually are. For increased accuracy, it is
recommended that bioassessments use reference conditions
composed of multiple reference sites, as opposed to single
upstream reference sites.
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xii
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Abstract
Combined sewer overflows (CSOs) are uncontrolled
discharges, during wet and dry weather, of mixtures
of untreated domestic sewage, industrial and commercial
wastewaters, and stormwater runoff. There has been
increasing interest in the effects of these discharges on the
water quality and ecological integrity of surface waters
receiving them. This document presents a discussion of the
components of pollution produced by CSOs, the use of
USEPA's rapid bioassessment protocols (RBPs) for
evaluating instream community level effects on the benthic
macroinvertebrate assemblage, and the potential for using
bioassessment results in the total maximum daily load
(TMDL) process, 305(b) reporting, biological criteria, and
other watershed management efforts.
' I
Application of the RBPs is presented in two case studies, in
Ohio and New York, where assessments were completed
and the results compared with historical assessments by the
Ohio Environmental Protection Agency (Ohio EPA) and
die New York Department of Environmental Conservation
(NYDEC). Overall, the current assessments in Ohio are
relatively consistent to Ohio EPA's assessments in 1986,
1988 and .1991; some assessment results varied slightly
between the 1991 and 1992 surveys. The current assess-
ments in New York are comparable to previous studies
conducted by NYDEC in 1989 and 1990.
Also presented is an evaluation of the effects of the level of
taxonomic identification and subsampling level on RBP
results. When we compared two versions Of the RBP
methodology which employ different levelsof identification
(family vs. genus or species), seven individual metrics
showed variability with the changing taxonomic level
while the total bioassessment scores were not affected. .
Results using family level identifications may be less
sensitive than genus/species level for those metrics that
depend on tolerance values and functional feeding group
designation. Although the total bioassessment scores were
not affected, the variability of the individual metrics, and
lower taxonomic resolution, can lead to difficulties in
interpreting the findings of the. total bioassessment scores
when family level identification is used. Comparisons
between two different subsample sizes (100 and 300
organisms) also showed no differences in the total bioas-
sessment scores; only two metrics (taxa richness and EPT
index) performed differently between the subsampling
efforts.
The results presented indicate that bioassessments, in
general, and RBPs, specifically, are found to be effective in
detecting the biological effects of CSOs..
-------
-------
1
Introduction
Combined sewer overflows (CSOs) are increasingly
being recognized as significant sources of water
quality impairment in some urban areas of the United
States. Several factors have contributed to CSOs not being
adequately controlled despite the fact that they are covered
under the Clean Water Act's National Pollutant Discharge
Elimination System (NPDES) permitting requirements.
They are a highly complex, site-specific technical problem
that is expensive to control, and the U.S. Environmental
Protection Agency (USEPA) has historically focused on
regulation of single chemical pollutants (Water Policy
Report 1994).
Combined sewer systems are state or municipally-owned
wastewater collection systems that channel sanitary
wastewaters and stormwater to a treatment facility. CSOs
are discharges from the sewer system prior to the treatment
facility of mixtures of untreated domestic sewage, indus-
trial and commercial wastewaters, and stormwater runoff.
CSOs usually result from a lack of sufficient storage
capacity at times of high precipitation. They often carry
high concentrations of bacteria and other microorganisms,
suspended solids, toxic pollutants, floatable solid wastes,
oil and grease, nutrients, and oxygen-demanding organic
compounds (USEPA 1994a).
1.1 Document Purpose
One of the purposes of this paper is to investigate a
potential tool for characterizing the biological effects of
CSOs. It is hoped that such a tool would aid in achieving
the characterization and monitoring portion of the Long-
Term Control Plans. Part of the Long-Term Control Plan is
to use cost-effective screening procedures for identifying
relative degrees of impairment to the ecosystem; biological
monitoring provides a mechanism for this. Additional
objectives of the paper are to present two case studies in
which biological assessments were used to evaluate CSO
impacts, to investigate the effects of variation hi sampling
and analysis methodology on assessment results, and to
examine potential application of bioassessment methods to
the total maximum daily load (TMDL) process and other
watershed management efforts. These efforts may include
development, of biological criteria, storm water and wet
weather monitoring, and preparation of 305(b) reports,
which are biennial reports prepared by each state to report
the status of the state's waterbodies. The audience for this
document is intended to be state bioassessment personnel,
programmatic staff overseeing CSO management and
control, and regional watershed protection coordinators.
1.2 Environmental Effects of
CSOs
Many of the limited existing data on CSOs are measure-
ments of effluent levels of physicochemical water quality
parameters (i.e., they measure stressors in the CSO di-
rectly). Stressors contained in CSOs may be physical (e.g.,
elevated temperatures, high velocity, heavy solids load),
chemical (e.g., organic loading, biochemical oxygen
demand, toxic pollutants), or biological (fecal coliforms) in
nature. The high energy and intermittent flows characteris-
tic of CSO discharges result in several physical effects in
the receiving waterbody, among them scouring of the
substrate, bank destabilization and erosion, and changes in
the morphometry (shape) of the waterbody (e.g., increased
channelization). The problems are probably most evident
in lotic (flowing) waters, and particularly where there is a
steep topographical gradient. The magnitude of the
physical changes in the waterbody is dependent on the
topography and geology of the area (e.g., how easily the
substrate is eroded), the volume and flow of the discharge,
the intensity of the storm event(s), and the amount of
increase over "normal" flow. It should be noted that these
physical effects are a function of the wet-weather flows and
discharges, not CSOs in particular; storm water discharges
can exert similar effects.
Numerous biological effects can occur hi the aquatic ecosys-
tem from the high flow. There might be an immediate, direct
loss of organisms and their habitats. For example, hi streams
and rivers, plants and animals might not be able to withstand
the greatly increased flows and might be swept downstream
(Seager and Abrahams 1990), where they might or might not
find suitable habitat The high and intermittent flows could
preclude the establishment or maintenance of vegetated areas
once they have been uprooted or undermined by the flow, and
curtail recolonization by benthic organisms after downstream
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
-------
drift. Thus, the loss of habitat and organisms might be
perpetuated.
CSO discharges are usually wanner than the receiving
waterbody, especially in summer. Moreover, urban streams
often lack shade, which raises ambient summertime
temperatures. The heavy sediment load in CSOs can
influence heat radiation in the water column (USEPA
1992), possibly by increasing heat retention by the particles
in the water column, thus maintaining the elevated tem-
peratures. Warm water cannot hold oxygen in solution as
well as cold; therefore, an indirect result of elevated .
temperature is lower dissolved oxygen in the water column.
While suspended in the water column, particulate matter
results in increased turbidity and reduced light penetration.
Ambient light levels can be further lowered by color
generated by materials in the discharges (or produced later
by subsequent algal blooms). Much of the material in
CSOs and storm water/runoff is relatively large (Field and
Turkeltaub 1981). In such a case the majority of the
material would settle out relatively quickly and light levels
could return to normal. If there is a significant percentage
of fine-grained silt and clays, however, the settling rates are
much slower and the elevated turbidity levels can be more
or less permanent The high flows characteristic of CSOs
can often cause a resuspension of potentially contaminated
sediments (including microbes and pathogens, toxic
substances, and metals) deposited from earlier storms.
CSOs have high levels of organic matter, which contribute
to biochemical and chemical oxygen demand (BOD, COD)
and thus to dissolved oxygen (DO) depletion in the water
and sediments. There appear to be immediate and delayed
stages in the high oxygen demand dynamics. There is an
immediate (i.e., during the storm event) peak of COD (Ellis
ซ et al. 1992), due to the physical forces that scour, flush, and
resuspend the sediment and associated material and due to
the relatively rapid degradation of the dissolved organic
compound portion of BOD. The delayed effects are due to
the degradation of the BOD associated with the particulate
matter (Lijklema et al. 1990; Hvitved-Jacobsen 1982),
which is more refractory.
The toxic qontents of CSOs are not well characterized
because they are site-specific, storm-specific, and depen-
dent on the relative proportions of the industrial waste,
domestic waste, and storm water components along with
the individual characteristics of each component How-
ever, numerous constituents that are highly toxic to aquatic
life have been documented in CSOs . These include heavy
metals (copper, lead, zinc, etc.), PAHs, and pesticides.
Non-priority pollutant toxic substances are also found.
Ammonia might be present in the discharge itself, shown
by peaks in instream NHj-N concentrations during a storm
event (Ellis et al. 1992). Ammonia might also be generated
within the sediment and released to the water column. Also
present are oil, grease, and gasoline, which have toxic
effects of their own and might be further contaminated with
various priority pollutants. There might be whole-effluent
toxicity due to mixtures or unknown constituents as well:
1.3 Biological Assessments
Biological assessments provide integrated evaluations of
water resource quality. They also can inllow inferences to
be drawn from a broad array of stressprs based on both
biological and physical habitat conditions. Impairments
can be identified from a variety of sources including water
column contamination, sediment contamination,
nonchemical impacts, and alteration of physical habitat
(Karr 1991). The instream communities act as continuous
monitors of water quality, assimilating impacts from
periodic spills, nonpoint source pollution, cumulative
pollutants, and other sources that might be missed during
sporadic chemical sampling (Ohio EPA 1987a; USEPA
1990a). Responses to natural habitat variability and
impacts from intermittent physical habitat change precipi-
tated by phenomena such as increased stormflows (e.g.,
sedimentation, scour, and modified flow characteristics)
will also be reflected by the biological community (Reins
1991; Burton and Harvey 1990; Hdlomuzki 1991; Cham-
bers et al. 1991; Jowett and Duncan 1990; Bums 1991;
Plafkin et al. 1989; Barbour and Striblling 1991; Karr et al.
1986; Ohio EPA 1987b). Because of the unpredictable and
fluctuating nature of storm events in urbanized watersheds
(Schueler 1987), characterization of the biological commu-
nity might provide a good measure of the cumulative
instream effects caused by CSOs and utormwater discharge.
Rapid bioassessment protocols (RBPs) have been devel-
oped for determining the status of macroinvertebrate and
fish community structure and function in streams and
wadable rivers (Plafkin et al. 1989). These methods
provide a relatively quick and cost-effective means of
compiling and analyzing information on the impairment of
aquatic communities from point or raonpoint source
pollution. RBPs currently serve as the foundation of the
bioassessment approach, being adapted by many water
quality agencies across the country. Forty-five states have
implemented or are developing biological monitoring
programs modeled after the RBPs or some other multiple-
parameter (multimetric) approach for characterizing
bentbic macroinvertebrate communities in the context of
habitat quality (Southerland and Stribling 1995). The RBP
concept is well-founded in ecological principles and uses
an information-gathering structure that categorizes and
assimilates information into community parameters or
metrics through the use of habitat and biological commu-
nity assessments.
Introduction
-------
The biological community analysis consists of standardized
field collection of benthic macroinvertebrates, and subsequent
calculation of a series of "metrics," each measuring a different
aspect of community structure and composition. The assess-
ment integrates the metrics and compares them to reference
values, allowing judgments to be made on what could be
expected at the test site if habitat and pollutant impairments
were corrected, as well as the current judgment of overall
biotic impairment. The investigator can also evaluate the
generic causes of impairments by examining the individual
metrics (Yoder 1991; Yoder and Raiikin 1995; Shackleford
1988). Different types of organisms have distinct reactions to
various types of stresses. For example, metrics which focus
on invertebrates that rely on paniculate organic matter, such
as leaf litter for food, could be used as a screening tool for
assessing the impact of bound contaminants or degradation of
die riparian vegetation.
Useful metrics for application of RBPs can vary by
waterbody type and geographic region (Plafkin et al. 1989;
Barbour et al. 1992). Ideally, they are selected based on
criteria that would document relevance, sensitivity, respon-
siveness, and practicality (Barbour et al. 1995). Following
pilot studies and evaluation of data and metrics, some
might be discarded based on failure to meet pertinent
criteria. Although the metrics used for the Ohio and New
York studies were taken directly from Plafkin et al. (1989)
and Barbour et al. (1992), their use does not necessarily .
imply that they are the most appropriate choices relative to
desirable criteria for metrics, such as responsiveness to
environmental degradation. Additional metrics might be
more appropriate for assessing CSOs, but developing and
testing metrics was beyond the scope of this project.
1.4 Reference Conditions
RBPs are based on the concept of comparison between a
study area and a reference condition or site. A reference
condition is the set of conditions of minimally impaired
waterbodies characteristic of a waterbody type for a given
region or subregion (Gibson 1994). The reference condi-
tion is made up of data from reference sites in a geographic
area (or "ecoregion") for waterbodies of the same class arid
serves as the benchmark for determining the biological
potential of test sites in that geographic region and of the
same class; it gives more accurate description of expected
conditions and the natural variability than do site-specific
reference sites. Regional calibration of metrics allows for
fine tuning of biological information so that the most
appropriate metrics are used for each specified ecological
stratum (e.g., type of waterbody) and the regional bound-
aries for metric variability are recognized. -
A reference site is a specific locality on a waterbody that
represents the expected biological integrity for other sites
on the same (site-specific reference site) or nearby
waterbodies (regional reference site). Site-specific refer-
ence sites have the potential to be affected by stressors
affecting the watershed. For that reason, we currently
recommend that several reference sites be used for com-
parisons if reference conditions have hot yet been devel-
oped for the region and site class. As more site-specific
reference sites are sampled and metrics tested and cali-
brated, they will serve as the foundation for building, a
reference condition database for waterbodies in the same
class and region. Further discussion on the topic of
ecological reference conditions and site-specific reference
data can be found in Hughes (1995).
The current study used one site-specific (upstream)
reference site and one regional reference site as the bench-
mark to determine the biological impairment of the test
sites. In some cases the regional reference site was
determined to be unsuitable for use as a reference due to
impaired biological condition; in these cases the site-
specific reference site was used for comparison. For the
current Ohio study, single regional reference sites were
used in addition to the upstream reference sites; however,
the historical assessments for Ohio are based on the >
regional reference condition. Two of the three rivers in the
current Ohio study (Scioto and Sandusky) are in the same
ecoregion (Eastern Cornbelt Plains) and thus might not
have required separate scoring criteria if regional calibra-
tion had been performed. This could be the source of some
differences in the biological assessment for some sites
between historic and current assessments. For the most
part, regional reference conditions provide more general
criteria for acceptable biological integrity.
Combined Sewer Overflows and the Multimedia Evaluation of Their Biological Effects: Case Studies in Ohio and New York
-------
-------
2
Methods
2.1 Habitat Quality Assessment
Habitat quality assessment is an essential part of any
assessment of ecological integrity (Karr et al. 1986; Plafkin
et al. 1989). The quality of the physical habitat at a site
identifies constraints on the attainable biological potential
of that site and provides information for interpreting
biosurvey results (Harbour and Stribling 1991). Numerous
components of the physical structure of stream environ-
ments and riparian habitat are critical to the ecological
integrity of lotic water resources, including channel mor-
phology (width, depth, and sinuosity); floodplain shape and
size; channel gradient; instream cover (boulders, woody
debris); substrate type and diversity; riparian vegetation and
canopy cover; and bank stability.
Specific habitat parameters and narrative descriptions of the
condition categories for which visual assessments of condition
ate made are shown in Figure 2-1. Some scoring systems have
some habitat characteristics weighted more heavily than others.
For instance, the parameter condition scoring framework
(Harbour and Stribling 1991) used for the 1992 Ohio study had
differential weighing for the primary, secondary, and tertiary
parameters with a maximum of 20,15, and 10 points, respec-
tively. However, with the testing of habitat assessment
consistency among multiple observers (Harbour and Stribling
1994), it became evident that the weighing could be a substan-
tial source of variability. The habitat scoring systems currently
recommended have all parameters weighted equally (Figure 2-
1); that is, on a 20-point scale. The scoring system used in
New York used equal weighing.
Parameters are visually inspected at each sampling location and
assigned scores within the continuum of conditions ranging
from optimal to poor based on the narratives. The scores ,
assigned to each parameter are totalled for a station. That score
is compared to the reference score to provide a relative
assessment of habitat quality that will assist in the interpreta-
tion of biological condition. The total score for each sampling
station is used in classifying the station, based on the percent
comparability to the reference condition ("expected" condition)
and the station's apparent potential to support the same level of
biological community development as that observed at the
reference station. Basic water quality data (temperature,
dissolved oxygen, pH, and conductivity) are also collected to
allow for further comparison among sites. Further discussion
of the logic and justification for the approach can be found in
several other documents (Plafkin et al. 1989; Harbour and
Stribling 1991,1994).
2.2 Benthic Macroinvertebrate
Sampling
For the benthic macroinvertebrate studies, a standardized
collection procedure based on RBPs (Plafkin et al. 1989)
was used to obtain samples of the macroinvertebrate fauna
from comparable habitat types at all stations. Sampling,
according to RBPs for high-gradient streams, is focused on
what is generally considered to be the most productive of
stream systems, riffles and runs. For the New York study,
three different RHP level assessments were conducted at
each station in order to compare assessment results from
the differing levels of effort (RBPI, RBPH, RBPffl).
2.2.1 Sampling and Sample Handling
Samples were obtained using a 1-m2 kick net (no. 30 mesh,
600 (am openings). Two 1-m2 samples were collected at
each station: one from a fast-water riffle and one from a
slow-water riffle. Sampling from both the fast and slow
riffle current velocities allows for a broader coverage of
variability within the riffle habitat. For those sampling
sites which lacked riffles, run areas with cobble or gravel
substrate were sampled instead. The two kick net samples
from each station were composited in die field, concen-
trated in a no. 30 (600 jam) sieve bucket, and emptied into a
gridded sorting pan for subsampling. For the Ohio portion
of the study, the gridded pan was a metal, porcelain-
covered pan with numbered grid squares drawn on the
bottom. For New York, a change in subsampling methods
was made to minimize movement of organisms among
grids and increase the standardization of the subsampling
effort. The standardized gridded screen (Caton 1991)
contains 30 clearly marked squares, each a uniform 6 cm x
6 cm. The gridded screen fits into another slightly larger
tray so that water can'be added to the sample to allow for
even distribution. When the screen is lifted out of the tray,
the sample contents settle onto the screen, effectively
restricting organism mobility.
Combined Sewer Overflows and the Multinietric Evaluation of Their Biological Effects: Gase Studies in Ohio and New York
-------
Figure 2-1. Habitat scoring system for streams with riffle/run prevalence.
UARITAT ASSESSMENT FIELD DATA SHEET
^^^^
Optimal
Greater than 50% mix of
boulder, cobble, sub-
merged logs, undercut
banks, or other stable
[habitat.
20 19
RIFFLE/RUN PREVALENCE
1. Inatream Cover
habitat; habitat availability
less than desirable.
SCORED
2. Eplfmunal
Substrate
14 13
Well-developed riffle and
run; riffle is as wide as
stream and length
extends two times the
width of stream;
abundance of cobble.
Riffle is as wide as stream
but length is less than two
time? width; abundance of
cobble; boulders and
gravel common.
Run area may be lacking;
riffle not as wide as stream
and its length is less than 2
times the stream width; ,
gravel or large boulders
and bedrock prevalent;
some cobble present.
Less than 10% mix of
boulder, cobble, or other
stable habitat; lack of
habitat is obvious. .
MMH^^^"^^"^""^^^""'
43 2
[Riffes or run virtually
nonexistent; large boulders
and bedrock prevalent;
cobble lacking.
3. Embeddedness
SCORE
Gravel, cobble, and
boulder particles are 0-
25% surrounded by fine.
sediment.
iGravel, cobble, and
boulder particles are 25-
50% surrounded by fine
sediment.
4. Velocity/Depth
Regimes
[All four velocity/ depth
regimes present (slow-
deep, slow-shallow, fast-
deep. fast-shallow).
| Gravel, cobble, and
boulder particles are 50-
75% surrounded by fine
sediment.
7
Only 3 of the 4 regimes
present (if fast-shallow is
Gravel, cobble, and
boulder particles are more
han 75% surrounded by
ine sediment.
Only 2 of the 4 habitat
regimes present (if fast-
Dreseni inta5i-siiaปuปซ '*> ,ซ.a....- r- ป- --
missing, score lower than if shallow or slow-shallow are
Dominated by
1 velocity/depth regime
(usually
slew-deep).
missing, score low).
,
missing other regimes).
Banks shored with gabion
New embankments present
Some channelization pres-
ent, usually in areas of
bridge abutments; evi-
dence of past channeliza-
tion, i.e., dredging, (greater
than past 20 yr) may be
present, but recent
channelization is not
nresent.
No channelization or
or cement; over 80% of the
on both banks; and 40 to
dredging present.
stream reach channelized
5. Channel
Alteration
80% of stream reach
channelized and disrupted.
6. Sediment
Deposition
Little or no enlargement of
islands or point bars and
less than 5% of the
bottom affected by
sediment deposition.
Some new increase in bar
formation, mostly from
coarse gravel;
5-30% of the bottom
affected; slight deposition
in pools.
Moderate deposition of new
gravel, coarse sand on old
and new bars; 30-50% of
the bottom affected;
sediment deposits at
obstruction, constriction,
and bends; moderate
deposition of pools
arevalent.
Heavy deposits of fine
SCORE
7. Frequency of
Riffles
Occurrence of riffles
relatively frequent;
distance between riffles
divided by the width of the
stream equals 5-to 7;
varietyj)f habitat.
1
B*M^H^^B^^ป*
Occurrence of riffles
infrequent; distance
between riffles divided by
the width of the stream
equals 7 to 15.
material, increased bar
development; more than
50% of the bottom
changing frequently; pools
almost absent due to
substantial sediment
deposition.
Occasional riffle or bend;
bottom contours provide
some habitat; distance
between riffles divided by
the width of the stream is
between 15 and 25.
Generally all flat water or
shallow riffles; poor
habitat; distance between
riffles divided by the width
of the stream is between
ratio >25.
Methods
-------
Figure 2-1. (continued)
Habitat
Parameter
8. Channel Row
Status
. ,'
SCORE
9. Condition of Banks
SCORE
10. Bank Vegetative
Protection
SCORE
1 1 . Grazing or Other
Disruptive Pressure
SCORE
12. Riparian
Vegetative Zone
Width (Least Buffered
Side)
SCORF
Category
Optimal
Water reaches base of
both lower banks and
minimal amount of
channel substrate is
exposed.
20 19 18 17 16
Banks stable; no
evidence of erosion or
bank failure.
20 19 18 17 16
More than 90% of the
streambank surfaces
covered by vegetation.
20 19 18' 17 16
Vegetative disruption,
through grazing or
mowing, minimal or not
evident; almost all plants
allowed to grow
naturally.
20 19 18 17 16
Width of riparian zone
> 1 8 meters; human
activities (i.e., parking
lots, roadbeds, clear-
cuts, lawns, or crops)
have not impacted zone.
2O 19 18: 17 16
Suboptimal
Water fills > 75% of the
available channel; or
< 25% of channel -
substrate is exposed.
15 14 13 12 11
Moderately stable;
infrequent, small areas of
erosion mostly healed
over.
15 14 13 12 -11
70-90% of the
streambank surfaces
covered by vegetation.
15 14 T3 12 1T?
Disruption evident but not
affecting full plant growth
potential to any great ,
extent; more than one-half
of the potential plant
stubble height remaining.
15 14 13 12 11
Width of riparian zone 1 2-
1 8 meters; human
activities have impacted
zone only minimally.
MS"''*14,' *3'' 12"<' ill -:
Marginal
Water fills 25-75% of the
available channel and/or
riffle substrates are mostly
exposed. ,
10 9 8 7 6
Moderately unstable; up to
60% of banks in reach
have areas of erosion.
10 98r T -6
50-70% of the
streambank surfaces
covered by vegetation. ,
10 ' ~W''-'-- 8 '7-"-*6"-v-V
Disruption obvious;
patches of bare soil or
closely cropped vegetation
common; less than one-
half of" the potential plant
stubble height remaining.
^"W"'-9>'ซ-&:* 7 "6 -
Width of riparian zone 6-
1 2 meters; human
activities have impacted
zone a great deal.
~1O-c.':9d.^8V!. "J^' 6
Poor
Very little water in
channel and mostly
present as standing pools.
5 4321 0
Unstable; many eroded
areas; "raw" areas
frequent along straight
sections and bends; on
side slopes, 60-100% of
bank has erosional scars.
5 4 3 2 1 0
Less than 50% of the
streambank surfaces
covered by vegetation.
5 4 3 2 1 0
Disruption of streambank
vegetation is very high;
vegetation has been
removed to
2 inches or less in average
stubble, height.
5 4 32 10
Width of riparian zone <6
meters: little or no riparian
vegetation due to human
activities.
5,4 3. 2 1 0
Total Score.
For subsampling, individual grid squares were randomly se-
lected, then organisms were removed from each selected grid
until the desired subsample number (300 organisms) was
reached. Then any large organic material (whole leaves,
twigs, algal or macrophyte mats) was rinsed, visually in-
spected, and discarded. Randomly selected grid squares were
completely sorted regardless of whether the number of organ-
isms was greater than that needed for the subsample. For the
Ohio study, organisms were removed from selected-girds un-
til the 300-organism subsample was reached. For the New
York study, a series of grids were chosen to constitute a 100-
organism subsample and a 200-organism subsample for each
sample. These subsamples were maintained separately for
identification and storage, then the data were totaled to create
the 300-organism subsample. Specimens for both studies
were placed in a pre-labeled sample container containing 70
percent ethanol and shipped to Monticello Ecological Re-
search Station (University of Minnesota, Monticello, Minne-
sota) for identification. \
2.2.2 Taxonomy
For the RBPIII assessments, all specimens were identified
to the lowest practical level, generally genus or species;
RBPII assessments used family-level identifications. Both
utilized primarily Merritt and Cummins (1984),
Wiederholm (1983), Brinkhurst (1986), and Thorpe and
Cbvich (1991). RBPI assessments consisted of field
identifications generally to the family level; some identifi-
cations were to order.
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
-------
2.2.3 Counting
For metrics calculated from taxa counts, pupae and adults
were not included in the calculations if larvae or nymphs of
the same taxon were identified in the sample. For those
metrics which use counts of individuals, pupae and adults
were included in the calculations. Exceptions are described
for the Ohio and New York data in Appendix A and B,
respectively. ,
2.3 Data Analysis
The data were analyzed using the multimetric approach
advocated by Karr (1986), Ohio EPA (1987a; b), Plafkin et
al. (1989), and Barbour et.al. (1995). Metrics were
calculated using the 300-organism subsamples from the
Ohio study. For the New York study, metrics were calcu-
lated based on both 100- and 300-organism subsamples at
both family-level and genus/species-level taxonomy.
Further rationale for each of these study designs is pre-
sented in Sections 3 and 4 of this document
V
2.3.1 Development of Bloassessment
Scoring Criteria
Bioossessment values derived from each metric are normal-
ized into bioassessment scores so that multiple metrics,
which yield a wide range of values, can be aggregated.
Scoring criteria are developed for each class of test sites,
stratified by geographic region and stream order, by
dividing the metric value range into equal quadrisections
ranging from the lowest possible value of a metric (usually
zero) to either the maximum value obtained or the 95th
percentile. The scoring criteria categories for Ohio were
equal quadrisections from the lowest possible value to the
maximum obtained. In most cases, the maximum value of
a metric was exhibited at regional reference stations or at
specific upstream stations. In the New York study, the
upper end of the range used was the 95th percentile, which
was used to control for outliers.
Using the appropriate scoring criteria table (Sections 3.2.1,
4.2.1), all calculated or enumerated metric values were
normalized into bioassessment scores (0,2,4,6), which
were summed for a total bioassessment score. The total
bioassessment scores of test sites were then compared to
the regional reference sites for each station. The test sites
were evaluated on the basis of their percent comparability
to the reference values. For two sites, the regional refer-
ence site was found to be impaired (e.g., Furnace Brook,
New York) or unable to be sampled (flooded) (e.g.,
Breakneck Creek, Ohio). Therefore, the upstream refer-
ence site (station CC1 and CR1, respectively) served as the
baseline for comparison. The suitability of both sites for
reference were further examined by deriving information
from individual metrics and habitat assessment parameters,
and the site CC1 was found to be slightly to moderately
impaired. CR1 also had a degraded biological condition
but was not given a rating. This illustrates the problems
which can arise when relying on a single reference site, and
therefore that the comparison should, when possible, be
made to reference conditions rather than to single reference
sites.
Some metrics include data from the reference site in their
calculation; these are known as "paired!" metrics. For those
sites that used the impaired upstream reference sites as a
baseline for comparison, paired metrics were not included
in the final assessment When biological scores are
summed using paired metrics, the site designated as the
reference site receives an automatic score of 6 (the highest
score) for each paired metric, which can artificially raise
the overall bioassessment score for that site. Therefore, if
the reference site is not minimally impaired (i.e., has some
degradation as does CR1 .and CC1), the site assessment is
given a score that indicates better biological condition than
it actually has, or would have if compaired to a truly
minimally impaired site.
In any biological assessment comparison of total bio-
. assessment scores to reference is but tine first step, which is
followed by inspection of individual parameters that allow
one to identify potential cause-and-effect relationships.
The severity of impairment (slight, moderate, etc.) is
determined by comparison with minimally impaired
conditions. The thresholds for impairment categories are
typically some portion of the distributi on of the conditions
of all sites. .For example, the 75th penxntile of the range of
scores can be considered the cutoff for nonimpairment To
do mis correctly, multiple (at least three) reference sites
should be used. However, these studies were designed with
only an upstream reference site and a regional reference
site. Thus, the assignment of narrative impairment catego-
ries, in general, is based on those found in Plafkin et al.
(1989)1 However, because the reference sites in New York
appeared to have organic enrichment, it was decided that
the actual impairment category should be interpreted as one
category less than those listed in Plafkin et al. (1989).
2.3.2 Metrics
The metrics used in the biological evaluation of sites
include eight "individual" metrics and four "paired"
metrics (Barbour et al. 1992). The paired metrics are those
which compare the test site to the upstream reference site
for the initial calculations. The following is a brief
description of the metrics and their calculations. It is worth
noting that some descriptions indicate what we expect to
find for "good" or "bad" situations for these assessment
(based on ecoregions or stream orders). However, the
metric value is actually scored good or bad as compared to
the reference condition or reference siite(s).
Methods
-------
Taxa Richness. Taxa richness reflects the health
of the community through a measurement of the
total number of taxa present Taxa richness is
calculated by counting the total number of distinct
taxa identified in the sample.. Generally, taxa
richness increases as water quality, habitat
diversity, and habitat suitability increase.
Hilsenhoff Biotic Index (HBI). TheHBIwas
developed by Hilsenhoff (1982) to summarize the
various tolerances of the benthic arthropod
community with a single value; tolerance values
range from 0 to 10, with 10 being assigned to
those taxa usually detected in the most degraded
situations (i.e., the most tolerant taxa). Only those
taxa for-which the tolerance values were available
were included in these calculations. The formula
for calculating the HBI is:
HM-2
n
where x. =
n =
number of individuals
within a taxon,
tolerance value of a
taxon, and
total number of indi-
viduals in the sample.
Following the Plafkin et al. (1989) document, the
HBI was modified to assess the total benthic
community not just arthropods and regional
development of tolerance values for various
environmental pollutants, in addition to organic
pollution (Hilsenhoff 1982, 1987; New York State
Department of Environmental Conservation,
Albany, New York, in litt 2/27/89; Illinois Envi-
ronmental Protection Agency, Marion, Illinois, in
litt 6/25/86; and Huggins and Moffett 1988). The
primary sources for tolerance values and func-
tional feeding group designations were regional
when possible (New York State Department of
Environmental Conservation, Albany, New York,
in litt 2/27/89) and USEPA (1990, draft report),
Those stations with a lower HBI value are inter-
preted as being in better condition, having a lower
abundance of individuals within tolerant taxa than
individuals in sensitive taxa.
Scraper Functional Feeding Group to Scrapers
plus Filterer Collectors (Scr/[Scr + FilJ x 100).
The relative abundance of scrapers and filterer
collectors reflects the riffle/run community
foodbase. When compared to a reference site,
shifts hi the dominance of a particular feeding type
indicate that a community is responding to an
overabundance of a particular food source.
Scrapers generally increase with increased diatom
abundance and decrease as filamentous algae and
aquatic mosses increase. However, filamentous
algae and aquatic mosses provide good attachment
sites for filterer collectors, which may then
increase in abundance. The organic enrichment
often responsible for overabundance of filamen-
tous algae can also provide fine organic particles
used by filterers. This metric reflects biotic
response to nutrient overenrichment. Higher
values are considered to indicate better condi-
tions. . '"--'.-
4. Individuals of Epheirieroptera, Plecoptera, and
Trichoptera (EFT) Taxa to EPT Taxa Plus
Chironomidae (EPT/[EPT + Chironomidae]).
This ratio is used as an indication of community
balance and compares the number of individuals
of Ephemeroptera, Plecoptera, and Trichoptera
(mayflies, stoneflies, and caddisflies, respectively)
to the number of individuals of EPT taxa plus
Diptera: Chironomidae (midges). A relatively
even distribution of all four groups indicates a
good biotic condition, as does substantial repre-
sentation of the sensitive groups Ephemeroptera,
Plecoptera, and Trichoptera. Environmental stress
is indicated by a disproportionately high number
of the generally tolerant Chironomidae, reflected
by lower values of this metric.
5. Percent Contribution of Dominant Taxon ([num-
ber of individuals of dominant taxon/total
number of individuals of all taxa in sample] x
100). The percent contribution of the dominant
taxon uses the abundance of the numerically
dominant taxon, relative to the rest of the sample,
as an indication of community balance. The
lowest practical taxonomic level (assumed to be
genus or species in most instances) yields a more
accurate assessment value for this metric. A
community dominated by only a few species
would indicate environmental stress; thus, lower
values for this metric are taken to reflect better
conditions.
6. EPT Index. The EPT Index is the total number
of distinct taxa within the Ephemeroptera,
Plecoptera, and Trichoptera (mayflies, stoneflies,
and caddisflies, respectively) and summarizes the
taxonomic richness of three groups of insects that
are generally considered to be pollution-sensitive.
This value increases with improving water quality.
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
-------
7. Shredder Functional Feeding Group to the Total
Number of Individuals Collected ([Shr/Total] x 100).
The abundance of the shredder functional feeding
group relative to all other individuals allows
evaluation of potential impairment to the riparian
zone. Higher ratios generally indicate better
conditions. Shredders should decrease in abun-
dance if their food source is reduced through
habitat alterations or contaminated by toxins.
8. Hydropsychidae to Total Trichoptera ([H/T]
x 100). Though caddisflies (Trichoptera) as a
group are usually considered to be pollution-
sensitive, a number of taxa within the
Hydropsychidae often greatly increase in abun-
dance and density hi degraded and organically-
enriched waters. This metric is calculated as the
number of individuals of Hydropsychidae to the
total number of individuals of Trichoptera in the
sample. Higher values reflect a dominance of the
hydropsychids (low caddisfly diversity), which
indicates poorer water quality.
9. Pinkham-Pearson Community Similarity Index.
This metric measures the degree of similarity in
taxonomic composition between the reference
sample and the test sample (Pinkham and Pearson
1976). A higher calculated value reflects a higher
degree of similarity to the reference sample and
presumably better conditions. It is calculated as:
j, tib)
^ maxhnum(xia tib)
where xu = number of individuals
in the ith species in
sample A
and
x = number of individuals
hi the ith species in
sample B.
10. Quantitative Similarity Index-Taxa (QSI-.
Taxa). This measure of comparative similarity in
taxonomic composition combined with relative
abundance between two sampling stations is based
on the concept of "percent similarity" (Whittaker
1952; Bray and Curtis 1957). It has been applied
by Shackleford (1988) in Arkansas streams and by
others in several individual studies in the mid-
Atlantic states. It compares two samples in terms
of presence/absence of taxa and relative abun-
dances and is calculated as: .
S^ = 2 min (pui pib)
where pta = the relative abundance
of species i at station A,
p. ' = the relative abundance
"lb .
of species i at station B,
and
min(pii,p4b) = the minimum
value of species i at station A. or
B in terms of relative abun-
dance.
Relative abundance is the percentage of individu-
als in the total sample that aris of species i.
Values for these calculations range from 0 to 100.
Samples that are identical have a score of 100;
those which have nothing in common have a
score of 0. Thus, those test stations which are
more similar to selected reference conditions, have
higher index values and are iinferred to have
better biological condition.
11. Dominants in Common - 5 (DIC-5). The DIC-5
compares the five dominant Saxa (as in greatest
abundance) between the reference station samples
and test station samples. For this metric, the top
five taxa (numerically) for each of the two
samples are listed. The number of taxa shared in
the top five list is the metric value. Values for
this metric range from 0 to 5 with 5 being most
similar to reference and 0 least similar.
12. Quantitative Similarity Index - Functional
Feeding Group (QSI-FFG). TheQSI-FFG
compares the relative abundance offunctional
feeding groups between two samples with the goal-
of showing changes in the'function of a commu-
nity. This metric is calculated hi the same way as
QSI-Taxa except that the numbers of individuals
are those within functional feeding groups:
filterer collectors, gatherer collectors, shredders,
scrapers, miners, predators, and parasites.
2.4 Quality Assurance/Quality
Control,
The quality control elements for the Ohio and New York
case studies are provided in Appendix C.
10
Methods
n n
-------
3
Evaluating the Biological Effects of
Combined Sewer Overflows in Ohio
/\ demonstration project was initiated to examine the
A. JLutility of biological assessment in general and RBPs
specifically for evaluating impairment due to CSOs. The
study objectives were to:
Evaluate the impact of CSOs on the benthic
macroinvertebrate assemblage at test sites by
identifying changes in taxonomic structure,
composition, and trophic function;
Determine the usefulness of RBPs in detecting
those effects; and
Evaluate the agreement of RBPs with historical
assessments produced by Ohio EPA.
f .
3.1 Site Selection and Location
Description
Three sites that have a history of CSO study were selected
for this investigation: the Scioto River at Columbus, the
Sandusky River at Bucyrus, and the Little Cuyahoga River
at Akron (Figure 3-1). These sites were selected because
they represent different regions of the state and are there-
fore likely to exhibit different biological expectations, and
because historical biological data are available. The sites
. were located with the intention of having one station
upstream of any CSO effects, one downstream of all CSO
inputs, another far enough downstream to perhaps be in a
recovery zone, and a fourth to represent regional reference
conditions for each stream (Table 3-1). However, the
regional reference site for the Little Cuyahoga River could
not be sampled due to flooding; that assessment was based
on an upstream condition.
3.2 Results
3.2.1 Taxonomy and Metrics
Taxonomic results and counting exceptions are presented in
Appendix A; the results of the metric calculations are
shown within the section for each CSO site.
Separate bioassessment scoring criteria were developed for
each river under study based on metric values acquired.
The scoring criteria are based on equal quadrisections of
the value range from the lowest possible value for a metric
(usually zero) to the maximum observed, usually observed
at the regional reference. The scoring criteria used for each
of the three sites are summarized by metric in Table 3-2.
3.2.2 The Scioto River at Columbus, Ohio
The Scioto River is a major tributary of the southern Ohio
River (Figure 3-1). It originates in northwestern Ohio in
Hardin County in what is known as Scioto Marsh (Ohio EPA
1979). It flows east 60 miles and then south 175 miles to its
confluence with the Ohio River at Portsmouth. The Scioto
River drainage area, approximately 6,500 square miles, dis-
plays a branching stream pattern with tributaries flowing
through gorges north of Columbus (Ohio EPA 1986). Flows
hi the river channel are regulated by two major impound-
ments and three low-head dams in the central Ohio stretch of
the river. Channelization with concrete reinforcement and
levees occurs hi some of the municipal areas; these channel
modifications continue to just upstream of the Jackson Pike
Waste Water Treatment Plant (WWTP) (River Mile [RM]
127.1). CSO outfalls are concentrated between RM 132.3
and 129.8 upstream of Jackson Pike. South of Jackson Pike,
evidence of impoundment and other channel modifications
disappears. The channel is typical of a lotic environment
with good sinuosity and riffle-pool sequences. The river is
situated over a buried valley filled with glacial outwash ma-
terial (sand and coarse gravel). Therefore, the substrate
ranges from milestone bedrock and silt/muck north of Cor
lumbus to coarse sand and gravel/cobble south of Columbus.
Flooding in this area has been known to cover extensive ar-
eas of the floodplain. This study covers the area of the Scioto
from 5 miles upstream of the confluence with the Olentangy
River (RM 132.3) to approximately 20 miles south of Colum-
bus at Circleville (RM 100.0) (Figure 3-2). At the northern-
most sampling station the drainage area of the Scioto River is
approximately 980 square miles; at the southernmost site it is
3,849 square miles. ,
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
11
-------
Little Cuyahoga River
Figure 3*1. State of Ohio; three river systems within which the CSO study occurred: the Scioto River at Columbus, the
Sandusky River at Bucyrus, and the Little Cuyahoga River at Akron. Honey Creek serves as a regional reference stream
for the Sandusky River.
12
Evaluating the Biological Effects of Combined Sewer Overflows in Ohio
-------
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Columbus
WhittierStCSO (129.8)
-Jackson Pike WWTP<127.1)
Sampling Station
Historical Data Site
O CSO Outfall
/\ Waste Water
v Treatment Plant
( ) River Mile
() Circleville
Figute 3-2. Cities of Columbus and Circleville, Ohio; Seioto River sampling stations, locations of historical data
collection, CSO outfalls, WWTP, and river mile designations (approximate scale 1 inch = 8.2 mUes).
patterns in this area of the Seioto River, located south of
Circleville. It is also an area characterized by glacial
outwash (C. Yoder, Ohio EPA, January 1993, pers. comm.),
a geological condition that contributes to the "degraded"
appearance of many large river channels. Stations S2 and
S3 arc apparently subjected to substantial bedload move-
ment along with dense growths of filamentous algae.
Gravel bars were present at Station S3, but were vegetated
with grasses, indicating that increases hi flow were not
frequent enough to flood or destabilize the bars. However,
the broader floodplain at Station S2 was not vegetated,
which indicated frequent flooding.
In spite of the sedimentation and bedload at the middle
stations, habitat should not be limiting to development of
the biological community. Differences hi biological
condition among Stations SI, S2, and S3 may, therefore, be
assessed hi the context of differences in water quality.
Habitat quality might be limiting at Station S4 compared to
the site-specific reference. However, Station S4 is consid-
16
Evaluating the Biological Effects of Combimsd Sewer Overflows in Ohio
-------
Table 3-3 Habitat assessments and physicochemical measurements of the Scioto River taken on 8
September 1992. For a description of the stations, see Table 3-2 and Section 3.2.2.2.
HABITAT PARAMETERS
Primary
Substrate Instream Cover
, Flow Canopy (0-20)
Secondary
Channel-Morphology (0-15)
Tertiary
Riparian and Bank Structure
(0-10)
TOTAL SCORE
Physicochemical
Parameters
t
Bottom Substrate/lnstream Cover
Embeddedness
Flow or Velocity/Depth
Canopy Cover (Shading)
_
Channel Alteration :
Bottom Scouring and Deposition
'Pool/Riffle, Run/Bend Ratio
Lower Bank Channel Capacity
, -
Bank Stability
Bank Vegetative Stability (Grazing)
Streamside Cover
Riparian Vegetative Zone Width
Dissolved Oxygen (mg/L)
Temperature (C)
Conductivity UcMhs)
SCORES
SCIOTO RIVER
SAMPLING STATIONS
SI
18
15
18
10
13
13
14
11
9
8
8
8
145
6.7
23.5
600
S2 '
16
14
16
10
11
12
11
8
8
8
8
9
131
8.9
24.9
590
S3
15
16
16
14
13
11
8
1.0.
9
8
8
8
136
8.9
24.8
600
84
17
11
16
8
9
9
8
8
6
7
8
10
117
8.4
23
750
ered to be an appropriate ecoregional reference by Ohio
EPA; therefore, the biological condition is expected to be
of a reasonably high quality.
3.2.2.3 Biological Assessments
Even though habitat quality was rated lower at the ecoregional
reference station at Circleville (S4) due to the river size and the
habitat parameters used (Figure 3-4), biological metrics
indicated good conditions (Table 3-4). The upstream station
(SI) scored only 79 percent of the ecoregional reference,
which indicated that the benthic assemblage was slightly
unpaired before exposure to the CSO discharge. There is an
increased abundance of midges at die two middle stations (S2
and S3), resulting in low values of the EPT/Chironomidae
ratio (metric 4), a result often seen in stressed situations. Also,
lower calculated values of the scraper/filterer collector ratio
(metric 3), seen in these same two stations, indicate increased
suspended organic particulates in the flow, perhaps resulting
from organic enrichment
Combined Sever Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
17
-------
Ohio EPA
(Historical)
Scioto River
(136.3) (129.0) (127.8)
1991 1991 1991
Vefy Fair Poor
Good
* 4 *
River 145
Mile
140.135
,127.1) Jackson Pike
WWTP
125 120 115 110 105
i
(100.0)
1992
Exceptional
(100.0)
1989
Exceptional
00 95 90
1
A RarigeJi
T ฐf T-
CSO \
| Outfalls)
;
' ! :
U.S.EPA
(this study)
S1A AS2 A S3
(136.4) (129.5) (127.7)
Slightly Moderately Slightly
Impaired Impaired Impaired
AS4
(99.9)
Non-
Impaired
Figure 3-3. Linear comparison with Ohio EPA assessments on the Scioto River.
Station S2, located approximately 4.5 miles downstream of
initial CSO outfalls and exactly at the location of the Whittier
Street CSO outfall (RM 129.5), received a bioassessment score
50 percent of the reference, indicating moderate impairment.
Downstream 2 miles, Station S3 had a bioassess-ment rating
that indicated slight impairment (69 percent of reference) and
some recovery from the conditions at S2.
3.2.2.4 Comparison to Historical Assessments
The Scioto River has the most extensive history of biologi-
cal monitoring and assessment of the three CSO sites under
investigation in this project'(Ohio EPA 1986). The results
from Ohio EPA seem to be comparable to those of the
present study in which Stations SI (RM 136.4) and S4'(RM
99.9) were found to be of-the best biological quality (Figure
3-3). Stations S2(RM 129.5) and S3 (RM 127.7) were
found to be moderately and slightly impaired. Ohio EPA
found its two nearest stations, kM 129.0 and 127.8, to be
fair and poor, respectively. The largest discrepancy in the
results between the present study and the 1991 Ohio EPA
study was between the farthest downstream station within
the zone of CSO outfalls, RMs 127.8 (Ohio EPA) and 127.7
(present). The former was found in 1991 to be hi "poor"
condition by the ICI and in "slightly impaired" condition
by the RBPs. This difference may be a sign of improve-
ment in water quality during the time between the two
sampling events. However, an alternative explanation is
that the differences in the macroinvertebrate communities
were due to the differences in flow between 1991 (a veiry
dry year) and 1992 (a very wet year). Ohio EPA data (Ohio
EPA 1992) suggest that more severe degradation in areas of
18
Evaluating the Biological Effects of Combined Sewer Overflows in Ohio
-------
CSO releases are experienced in the dry years. This may be
due to the material deposited by CSOs in previous years
which may exert strong effects on biologoical factors such
as 02 demand. If a community is already stressed from low
flow, changes in 02 demand would more quickly cause an
impact on it.
3.2.3 The Sandusky River at Bueyrus, Ohio
The Sandusky River is a major tributary to Lake Erie, its
drainage area occupying 1,420 square miles of predomi-
nantly agricultural land in north-central Ohio (Figure 3-1).
It flows east to west from its headwaters to Upper
Sandusky, where it turns north and discharges into
Sandusky Bay, the largest embayment on the southern
shore of Lake Erie. The major urban areas in the basin
include Fremont, Tiffin, Upper Sandusky, and Bueyrus.
Within the study area, the Sandusky River is predominantly
unmodified and free-flowing. Minor channel modifications
have occurred at RM 110.8 downstream from the Bueyrus
WWTP. The majority of the Sandusky River is predomi-
nated by bottom substrates of cobble, gravel, and boulders.
~ - , t --,'
3.2.3.1 Historical Information
A survey"of the Sandusky in 1980 revealed significant
impacts by CSOs, particularly downstream of Bueyrus. A
study done in 1990 compared assessments after modifica-
tions were made to the Bueyrus WWTP (Ohio EPA 1991)
with results from 1980. Trend assessment data showed that
there was a general improvement in fecal coliform bacteria
since 1979, though high counts still occurred downstream
of CSO outfalls (Ohio EPA 1991). The WWTP was
upgraded in 1988 and was successful in reducing, but not
eliminating, CSO loadings. An improvement in the
condition of the benthic macroinvertebrate assemblage
downstream of the WWTP outfall (comparing 1990
samples to 1979 samples) reflects this plant upgrade.
CSOs within Bueyrus were identified hi 1979 as a
significant source of organic degradation; moderate
impacts to the invertebrate assemblage continued as
recently as 1990. .
Upstream of Bueyrus, a marginal decline in the condition
of the fish assemblage was detected hi 1990 as compared
to that of 1979. As of 1990, the fish assemblage had
shifted to more tolerant species, resulting in nonattainment
of the state biocriteria for this river. Downstream of the
WWTP, slight improvement hi the fish assemblage was
detected between 1979 and 1990. As with the macro-
invertebrates, this increase hi biological condition can -
be partially attributed to the WWTP upgrade in 1988.
Additional improvement hi the fish assemblage is ex-
pected since it is not unusual for recovery in fish popula-
tions to lag behind improvements in water chemistry and
macroihvertebrate community structure (C.O. Yoder,
personal communication).
3.2.3.2 Sampling Station Descriptions and Habitat
Quality Assessments
Four sampling stations on the Sandusky River were
selected for this study of Bueyrus CSOs (Table 3-1); habitat
assessment rating scores; along with measurements of
dissolved oxygen, temperature, and conductivity, are
presented in Table 3-5.
Sandusky River upstream ofHwy. 30 bridge - Station SA1
(upstream reference). No habitat problems are evident at
this station. The riparian zone is hi an undisturbed condi-
tion, and there was tittle obvious sedimentation occurring.
However, the riffle from which the samples were taken
appeared as if it had been constructed, perhaps in an effort
to enhance fish habitat with larger and deeper pools
upstream and downstream. The riffle was composed of
various-sized boulders, some very large. The upstream and
downstream pools were too deep to wade in, and it ap-
peared that the rocks had been removed from them for
placement in the riffle. There was no indication of how
long the riffle had been hi place to allow for colonization.
Nonetheless, habitat quality was unquestionably in the best
condition of the Sandusky sampling stations, as it received
an RBP habitat score of 153 (Table 3-5, Figure 3-4).
Sandusky River at Aumiller Park - SA2 (CSO impact). This
station is located approximately 700 meters upstream of the
Bueyrus WWTP at the downstream edge of Aumiller Park.
Ohio EPA has indicated that the majority of CSO input is at
this park. Here the river is experiencing severe physical
disruptions apparently unrelated to CSOs. Heavy sedimenta-
tion is occurring due to the activity of heavy machinery
approximately 150 meters upstream and bank failure at the*
station. Habitat quality ratings were in the marginal or poor
category for embeddedness, all of the channel morphology
parameters, and riparian vegetative buffer zone width. This
station received a habitat quality rating score of 81.
Sandusky River downstream of Bueyrus, upstream of
WWTP- SA3(CSO impact). Station SA3 is located
approximately 50 meters upstream of the Bucyrus WWTP
and is downstream of most CSO outfalls. The station could
not be located farther downstream of the CSOs due to the
WWTP. According to Ohio EPA, there are numerous
outfalls along the 700- to 750-meter stretch" of the river
between Aumiller Park and the WWTP. The river here
rated suboptimal. and marginal for embeddedness, width of
riparian zone, bottom scouring, and deposition, and it had a
low pool/riffle, run/bend ratio. (Throughout the entire
reach of the river walked, approximately 750 meters, only
three riffle areas were found.) One bank is part of an old
landfill and is composed of soil completely interspersed
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
19
-------
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Evaluating the Biological Effects of Combined Sewer Overflows in Ohio
-------
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Table 3-5 Habitat assessments and physicochemical measurements of the Sandusky River taken
on 9 September 1992. For a description of the stations, see Table 3-2 and Section 3.2.3.2.
Ill III I
HABITAT PARAMETERS
Primary
Substrate Instream Cover
Row Canopy (0-20)
Secondary
Channel-Morphology (0-
15)
Tertiary
Ripan'an and Bank
Structure (0-10)
TOTAL SCORE
Physicochemical
Parameters
Bottom Substrate/lnstream Cover
Embeddedness
Flow or Velocity/Depth
Canopy 'Cover (Shading)
SCORES
SANDUSKY RIVER
SAMPLING STATIONS
SA1
17
16
19
18
Channel Alteration
Bottom Scouring and Deposition
Pool/Riffle, Run/Bend Ratio
Lower Bank Channel Capacity
12
11
14
12
Bank Stability
Bank Vegetative Stability
(Grazing)
Streamside Cover
Riparian Vegetative Zone Width
Dissolved Oxygen (mg/L)
Temperature (C)
Conductivity (//Mhs)
9
8
8
9
153
8.6
19
750
SA2
10
5
16
16
3
2
4
8
5
6
5
1
81
7.7
20
700
SA3
10
8
16
18
13
7
7
11
8
8
8
2
116
6.9
16
650
SA4
18
17
18
10
13
12
13
11
9
9
8
5
143
9.5
21
450
with broken glass and rusted pieces of metal. However,
enough soil is present to have been colonized by some
woody and herbaceous vegetation. This station rated 116.
Honey Creek at Melmore (Hwy. 100) - SA4 (regional
reference). This station is an Ohio EPA regional reference
site. Even though the weather conditions were sunny and
warm, the water level seemed to be up and, in fact, slightly
rising while on-site. The water also appeared somewhat
turbid. There might have been some rainfall upstream in
the watershed causing these conditions. Aspects of the
habitat that rated in the suboptimal or marginal ranges were
related to channel capacity and the vegetated buffer zone.
Water appeared to have intermittently escaped the channel
on the side with a low bank. Also, the width of the. riparian
vegetative zone is reduced on one side by agricultural fields
and on the Other by mowing. In particular, the zone on the
mowed side had a buffer zone of woody vegetation only
approximately 3 to 6 meters wide. The habitat assessment
rating score was 143.
The condition of the instream habitat and channel morphol-
ogy at the Aumiller Park station (SA2) is indicative of
considerable physical degradation. It might prove to be
22
Evaluating the Biological Effects of Combinisd Sewer Overflows in Ohio
-------
limiting to the development of the benthic macroinverte-
brate assemblage. Station SA3, just upstream of the
WWTP and the downstream-most station on this river, has
substantial riparian degradation and embeddedness with
some evidence of scour, but it should provide habitat that
will allow development of the benthic assemblage to a level
comparable to that of the reference conditions. The best
habitat encountered on the Sandusky was at the Fish
Hatchery station (SA1), the Ohio EPA upstream reference
station; the regional reference station habitat scored slightly
less than SA1 but was comparable. .
3.2.3.3 Biological Assessments
In the Sandusky River system, the regional reference
(Figure 3-5; Honey Creek at Melmore, SA4) produced a
total bioassessment score of 60. Station SA2, the upstream
CSO-impact station at Aumiller Park, was most comparable
to the regional reference at 83 percent comparability for
biology (Figure 3-4), indicating nonimpairment; the slight
reduction in biological condition was likely due to prob-.
lems in habitat quality at this station. The downstream
impact station, SA3, was slightly impaired, producing a
habitat assessment score 73 percent comparable to the
regional reference (Table 3-4); The bioassessment score
least comparable to the, regional reference was 67 percent at
Station SA1, the upstream reference; this could be due to
the habitat at SA1 being somewhat different with an
apparently human-constructed riffle. Though this station
was rated higher in habitat quality, the substrate composi-
tion might have had an effect on comparisons with the
downstream stations, the substrate of which was primarily
embedded cobble and gravel. Overall, the slight decrease
in biological condition from SA2 to SA3 is attributed to
additional CSOs and urban runoff, which further impaired
the biological community in an area of increased habitat
quality. These findings concur with the 1990'Ohio FJPA
survey of the Sandusky River (Ohio EPA 1991).
3.2.3.4 Comparison Jo Historical Assessments
The most recent Ohio EPA macroinvertebrate sampling on
the Sandusky River, in 1990, categorized the macroinverte-
brate assemblages at RMs 115.0 and 111.4 as "exceptional"
and RM 111.1 as "marginally good" (Ohio EPA 1991)
(Figure 3-6). The current study shows station SA1 (RM
115.0), the farthest upstream station, to be slightly impaired
at 67 percent comparability to the regional reference station
at Honey .Creek (SA4) due to an apparent habitat alteration.
Differences between the current study and that of Ohio EPA
(Figure 3-6) might be attributed to gear differences (artifi-
cial substrate samplers by Ohio EPA and instream substrate
in the current study). It is likely that sampling the bottom
substrate directly with the kick net is demonstrating the
difference in the habitat quality (substrate) at the two
different stations, whereas use of artificial substrate
samplers might have masked that difference by providing
suitable "habitat" for colonization. Therefore, effects on
the biological community observed when using artificial
substrate might better reflect pure water quality differences.
Another factor could be the use of Honey Creek as a site-
specific reference in the current study; Ohio EPA uses Honey
Creek as one of the 133 reference streams that make up its
reference condition for this class of stream. As stated earlier,
the use of multiple reference sites (or reference conditions) are
preferable to single, reference sites. It should also be noted that
the habitat disturbance at station SA1 noted in 1992 might
have occurred after the 1990 sampling was conducted, but it
was not possible to be certain. RBP samples were taken at
RMs 111.5 and 111.1 (SA2 and SA3, respectively), bracketing
the station found to be "exceptional" by Ohio EPA (1991).
Comparability to the regional reference at SA2 was at 83
percent or "nonunpaired"; SA3 was 73 percent or "slightly
impaired." Even with habitat problems at S A2 (RM 111 .5),
there was little indication of biological impairment compared
to the regional reference.
At the downstream station (SA3, RM 111.1), there was
slightly less habitat degradation in the form of scour and
embeddedness but a further decrease in biological condition.
Habitat problems at SA3 compared to SA2 were not as severe
as those seen at SA2. Therefore, the slight biological impair-
ment noted at S A3 can be attributed to influence from addi-
tional CSOs and urban runoff rather than habitat
This assessment of slightly impaired biological condition at
SA3 (RM 111.1) is similar to the Ohio EPA 1990 assessment
(marginally good), which was also attributed to CSO inputs.
These results seem to be compatible with those included in the
most recent historical assessment reports (Ohio EPA 1991)
(Figure 3-6). Additionally, SA2 might have experienced
organic or fertilizer loading mat caused a positive response of
the benthic community (nonimpaired assessment). The initial
phase of nutrient loading (organic enrichment) can mask the
effects of habitat degradation by elevating the biological
community (plants and animals). As organic enrichment
increases, however, the bloom in the biological community
begins to have adverse effects on the waterbody. For instance,
algal blooms cause reduced light penetration below the water's
surface and the bottom-dwelling plants die. As the abundant
plant material decays, oxygen is used up rapidly, which causes
further stress, and eventual more severe impairment of the
biological community. Thus, while organic enrichment in the
initial phase has a positive effect on the biology, it cannot be
sustained over a longer periods of time.
3.2.4 The Little Cuyahoga River at Akron,
Ohio
The Little Cuyahoga River flows through Akron in northeast-
em Ohio. The study area begins just downstream of Mogadore
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
23
-------
Melmore
Bucyrus
A Sampling Station
CSO Outfall
/> Waste Water
Treatment Plant
( ) River Mile
Figure 3-5. Cities of Bucyrus and Melmore, Ohio; Sandusky River and Honey Creek sampling stations, locations of
historical data collections, CSO outfalls, WWTP, and river mile designations (approximate scale 1 inch = 6.0 miles).
Reservoir. Of the three stations sampled, the two downstream
stations (CR2 and CR3) were expected to be receiving CSO
input It was later discovered that the outfalls upstream of the
middle station had been eliminated in the past 5 years, leaving
only the lower station to provide biological data expected to
reflect response to pollutant input This situation might allow
the middle station to yield information on biological recovery
following removal of CSO outfalls.
3.2.4.1 Historical Information
A bentbic survey was conducted in 1986 on the Little
Cuyahoga River. The ICI results indicated a combination
of urban runoff and enrichment problems from lake and
wetland drainage. These impacts resulted in a fair to poor
ICI rating for most of the river between RMs 9.6 and 1.8.
The three sampling stations in the present study were also
sampled in 1986: RMs 11.2 (RM 11.3 in present study), 7.1,
and 0.3. However, of these three stations, only RM 6.3 was
sampled in 1991 by Ohio EPA. In 1991, at RM 0.3 (upstream
of the confluence with the Cuyahoga), the ICI reached the
"fair" range and was essentially unchanged from 1986 (Ohio
EPA 1994). In 1986, however, the condition of macroinverte-
brate assemblage at RM 0.3 was lower than sites well
upstream. The poor conditions were characterized by
reductions in taxa richness, mayfly and caddisfly richness and
abundance, and sharp increases in the jjercentage of tolerant
invertebrate populations. These results were attributed to
CSOs, urban runoff, and industrial point sources in Akron.
Only a slight improvement (from poor to fair) was noted in,
1986 at RM 0.3 when compared to the next upstream site at
RM3.8.
24
Evaluating the Biological Effects of Combined Sewer Overflows in Ohio
-------
Sandusky River
(Upstream of 115.0)
Ohio EPA
(Historical)
1979-1990 Marginal Decline in Fish IBI
1990 Non-Attainment in Fish Community
(115.0) 1990
ICI Exceptional
(Within 10 mites downstream of 111.0)
':
1979 Severe Impairment
1990 Moderate Impairment
(111.4)1990
ICI Exceptional
(111.1) 1990 ICI Marginally Good
Sandusky River
River
Mile
122 120 118 116 114 1j
I I I N
U.S. EPA
(this study)
SA1
(115.0)
Slightly
impaired
(111.0) BucyrusWWTP
110 108 106 104102100
I ป II 1 i ^
(111.5) .(111.1)
Non- Slightly
Impaired. Impaired
Figure 3-6. linear comparison with Ohio EPA assessments on the Sandusky River.
3.2.4:2 Sampling Station Description and Habitat Quality
Assessments
The three sampling stations on the Little Cuyahoga River
selected for this study are presented in Table 3-1 and
Figure 3-7. On visiting the regional reference stream used
by Ohio EPA for the Little Cuyahoga (Breakneck Creek at
Kent), it was found to be flooded out of its banks. Sam-
pling could not be completed; therefore, the upstream
reference station was used for comparison., Habitat -
assessment rating scores are provided in Table 3-6.
Little Cuyahoga Rive? at Mogadore, Ohio - Station CR1
(upstream reference). This station is located approximately
2 miles downstream of releases from the dam of Mogadore
Reservoir, well within the range within which physical
channel alterations have been observed as a result of dam
operations (Gordon et al. 1992; Rochester et al. 1984).
However, this location was about 0.3 mile upstream from
the station recommended by Ohio EPA as the reference
station, which was inaccessible due to high flows. The
station sampled contained no riffles; therefore, the samples
were taken from runs. There was minimal variability of
depths in the channel, a very strong flow, and substrate
particles of mostly large cobble and small boulders with
considerable embeddedness due to sand deposition. The
sand was apparently coming from a sand and gravel pit
upstream several hundred meters on one side of the stream
channel. Station CR1 received marginal or poor scores on
scouring/deposition; pool/riffle, run/bend ratio; and those
parameters related to the riparian zone. This degradation is
consistent with that expected downstream of dams
Combined Sewer Overflows and the Multimctric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
25
-------
kron
A Sampling Station
CSO Outfall
O Waste Water
Treatment Plant
( ) River Mile
Figure 3-7. City of Akron, Ohio; Little Cuyahoga River sampling stations, locations of historical data collections, CSO
outfalls, WWTP, and river mile designations (approximate scale 1 inch = 4.5 miles).
(Rochester et al. 1984). The overall habitat assessment
score for CR1 was 107 (Table 3-6)..
Little Cuyahoga River at Massillon Road bridge (State Rte.
241) - Station CR2 (upstream). Station CR2.is located in a
heavily urbanized area of Akron (commercial/industrial/
transportation). Components of habitat structure that were
rated as suboptimal to poor included parameters related to a
reduction in riparian vegetation and lack of variability in
bottom contours, though some deep pools were present and
there was diversity of substrate particle size. Riffles were
at a minimum and samples were taken from runs. There
was a stability of bank structure normally unexpected in
such heavily urbanized areas. Habitat received an
assessment score of 116, comparable to that of the
reference station.. ,
Little Cuyahoga River at the Police Firing Range off
Cuyahoga Street - Station CR3 (CSO impact). The Little
Cuyahoga River at Station CR3 experienced some sedimen-
tation reflected in the rating scores for embeddedness, and
scour and deposition. At this level the river is a straight
channel without much variability in bottom contours, and
substrate particle sizes were limited mostly to sand with
some cobble and gravel. As at CR2, there were no true
riffles; samples were taken from run areas. The station
scored 115 on the assessment of habitat quality and was
considered comparable to the reference station.
26
Evaluating the Biological Effects of Combimsd Sewer Overflows in Ohio
-------
Table 3-6 Habitat assessments and physicochemical measurements of the Little Cuyahoga River
taken on 24 September 1992. For a description of the stations, see Table 3-2 and Section
3.2.4.2.
HABITAT PARAMETERS
Primary
Substrate Instream
Cover Flow Canopy (0-
20)
Bottom Substrate/lnstream Cover
Embeddedness
Flow or Velocity/Depth
Canopy Cover (Shading)
. SCORE
LITTLE CUYAHOGA RIVER
SAMPLING STATIONS
V
CR1
14
11
11
8
CR2
- -
17
15
15
11
CR3
14
15
10
10
Secondary >
Channel-Morphology
(0-15)
Tertiary
Riparian and Bank
Structure (0-10)
Channel Alteration
Bottom Scouring and Deposition
Pool/Riffle, Run/Bend Ratio
Lower Bank Channel Capacity
14
7
9
11
14
11
10
7
14
8
4
13
Bank Stability
Bank Vegetative Stability (Grazing)
Streamside Cover
Riparian Vegetative Zone Width
TOTAL SCORE
Physicochemical
Parameters
Dissolved Oxygen (mg/L)
Temperature (C)
Conductivity U/Mhs)
9
5
6
2
107
8
17
320
9
2
4
1
116
7.9
15
320
8
6
8
5
.115
4
2
400
Overall, the Little Cuyahoga River, in the reaches of this
study, has had considerable habitat degradation mostly from
sedimentation and alteration of the riparian zone. However,
the components of habitat quality that exhibited degrada-
tion were relatively consistent throughout the study area,
and the resulting habitat scores were comparable at all three
stations (Table 3-6). Thus, direct comparisons of the
biological data among these stations should be possible and
any observed differences can be interpreted to be the result
of water quality problems.
3.2.4.3 Biological Assessments
Examination of metric values for the upstream reference
station CR1 revealed a degraded biological condition. An
increase in filterer collectors resulted in a low scraper to
scraper + filterer ratio indicating potential organic pollution
problems. The percent contribution of dominant taxon (78
percent Hydrosphychids), indicate poor community balance
and account for the increase in filterers. Therefore, with no
regional reference for comparison, this site (CR1) was not
given a rating. The percent comparisons to reference
(GR1) for stations CR2 and CR3 were made using metric
totals without paired metrics; each assessment category was
interpreted as one category less than those listed in Plafkin
(1989) since the comparison was made using an impaired
reference site.
The condition of the bentbic community at station CR2 was
considerably better than either the upstream or downstream
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
27
-------
stations (CR1 and CR3, respectively). Although many taxa
at this station were relatively tolerant, the taxa richness was
the highest among the three stations and the percent
contribution of dominant taxon was low.
A slight difference in condition of the benthic community
was detected at the downstream station (CR3), which was
86 percent comparable to the upstream reference (Figure
3-4, Table 3-4). Because the habitat assessment was
within the same range as that at CR1, the difference should
be attributable to water quality. Specifically, there was a
distinct depression in biological condition at CR3 (as
exhibited by the metrics taxa richness, EPT-Chironomidae
ratio, Pinkham-Pearson Community Similarity Index,
DIC-5, and QSI-taxa), indicating the potential presence of
toxicants from the CSO input. Abundance of invertebrates
at both the middle and downstream stations was unexpect-
edly low (Appendix A): at CR3 a total of only 60
specimens were collected; at CR2,133 specimens were ia
the total sample. At CR2 and CR3, a complete removal of
organisms was required from the double-composite kick
net samples in contrast to CR1, where a 300-organism
subsample was taken. CR2 is considered to have a
slightly impaired biology; CR3 is considered severely
impaired.
3.2.4.4 Comparison to Historical Assessments
There are considerable habitat and discharge problems
upstream of RM 11.0 along the Little Cuyahoga River (C.
Yoder, pers. comm.). During low flow years, DO problems
lead to decreased ICI values and thus lower bioassessment
ratings. Ohio EPA found the upstream station of the Little
Cuyahoga River (RM 11.2) to be in "fair" condition in
assessments in 1986.
The upstream site assessment for the current study, (CR1 at
RM 11.3) could not be rated due to evidence of biological
impairment at the site and the lack of an accessible regional
reference site to sample for baseline comparisons. Com-
parison to a degraded reference site falsely elevates the test
site assessments. Thus, due to the degraded biological
condition at CR1, the upstream reference site, assessments
for CR2 and CR3 were lowered by one category.
Just above RM 11.0, a tributary from a natural and rela-
tively undisturbed lake (Wingfoot Lake) enters the Little
Cuyahoga River. This tributary entering above RM 11.0 is
at least as large as the Little Cuyahoga upstream. This flush
of clean water likely accounts for the Ohio EPA ratings of
"good" and "very good" at the RM 11.0 station from 1986
to 1991 (Figure 3-8).
Just upstream of the CSO zone at RM 7.1 (Station CR2),
the current RBP assessment found the stream to be
"slightly-impaired", apparently somewhat improved over
the 1986 ICI rating of "fair." This finding might reflect
improvement following the removal ofCSOs. While thซ
biological condition along the entire reach of the Little
Cuyahoga (RM 0.3 - RM 11.3, excluding RM 11.0),
exhibits degradation, the station at RM 7.1 seems to have
rebounded slightly since the removal of the upstream CSO
outfall. At RM 0.3, the ICI (Ohio EPA 1986 and 1991) and
RBP assessments were in agreement, with macroinverte-
brate community evaluations of "fail-" and "moderately
impaired," respectively.
Results from the present study are consistent with those
obtained by Ohio EPA in previous surveys (1986 and
1991). The macroinvertebrate assemblage at RM 0.3
(Station CR3) reflects an impaired condition that has been
present since at least 1986 probably attributable to the
combined influence of CSOs and industrial input. One
station upstream of the CSO outfalls (CR1) was in similar
condition to that indicated from a 1985 assessment; Station
CR2 apparently improved following CSO removal.
28
Evaluating the Biological Effects of Combined Sewer Overflows in Ohio
-------
Ohio EPA
(Historical)
Little Cuyahoga River
(11.0) 1991
Very Good
(0.3)
Fair
(11.2) 1986 -ft
Fair
(11.0) 1986 f (7.1) 1986
Good Fair
(3.8) 1986
Poor
t(0.3)
1986
Fair
Mile
654321 ซ0cinw
i i i* i i i TI now
II M
rr i i i i
i
i i r i ii ii
" f
Range of CSO Outfalls |
U.S. EPA
(this study) A A
CR1 (11.3) CR2(7.1)
Degraded biological Slightly
condition, not rated Impaired*
(no reference for
comparison)
, A .
CR3 (0.3)
Severely
Impaired*
Figure 3-8. Linear comparison with Ohio EPA assessments on the Little Cuyahoga River.
*It should be noted that if an appropriate (non-impaired) reference condition was used as a baseline for comparison, all
test sites for this study would likely receive lower biological assessment ratings. ,
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
29
-------
-------
4
Evaluating the Biological Effects of
Combined Sewer Overflows in New York
As a followup to the Ohio study, a design for an additional
CSO bioassessment case study was developed. For this
study, the State of New York was selected for the following
reasons:
Active CSOs are known to exist in several cities of
the state.
ฐ Historical data and assessments would likely be
available. ,
The-state is dedicated to biological monitoring.
and assessment.
In addition to the objectives of the Ohio project (Section
3.0), the New York study was also designed to evaluate the
effect of method variation on RBP performance: specifi-
cally, when varying the level of method intensity and rigor
(screening level assessment, subsample size and taxonomic
level), are the same conclusions reached regarding
impairment of water resource integrity? The different
levels of taxonomy are meant to roughly correspond to
RBPII (family-level) and RBPIII (genus/species-level).
RBPI has no standardized sampling and is based primarily
of hand-turning of the substrate (cobble and gravel) and an
estimate of relative abundance of higher taxonomic groups
(i.e., family or order). Thus, the additional objectives for
this study are meant to examine the effects of these
differences on assessments; they are:
To evaluate the ability of RBPI to detect CSO
effects on the aquatic biota;
To evaluate the effects of taxonomic level (family
vs. genus/species) on metric behavior and overall
assessments; and
To evaluate the effects of subsample size (100-
organism vs. 300-organism) on metric behavior
and overall assessments.
RBPIII results are presented in this section; the evalua-
tions of method variation are presented in Section 5.
4.1 Site Selection and Location
Description
Eleven sampling stations were selected for this investiga-
tion: three stations each for the CSO-affected streams,
Canastota Creek, Harbor Brook, and Onondaga Creek, and
one station each for two regional reference sites on the
Tioughnioga River (West Branch) and Furnace Brook
(Table 4-1). Sampling stations on CSO receiving streams
had the same general placement as in the Ohio study, with
one location upstream of CSO outfalls, another downstream
of at least initial CSO outfalls, and the third well down-
stream of any outfalls. The stations on Onondaga Creek,
Harbor Brook, and Furnace Brook are located in Syracuse;
those on Canastota Creek and the Tioughnioga River are in
Canastota and Homer, respectively (Figure 4-1). There- ,
giqnal reference site selected by the New York Department
of Environmental Conservation (NYDEC) for Onondaga
Creek was the West Branch Tioughnioga River. Furnace
Brook, south of Syracuse, was selected as the regional ref-
erence for Canastota Creek and Harbor Brook but was sub-
sequently dropped after the evaluation of the biological
metrics indicated impairment; the upstream reference site
on Canastota Creek was used for reference instead. Table
4-1 presents detailed descriptions of sampling locations.
4.2 Results
4.2.1 Taxonomy and Metrics
Taxonomic results and counting exceptions are presented in
Appendix B. Bioassessment scoring criteria were devel-
oped by dividing the metric value range into equal
quadrisections, from the lowest possible value of a metric
score (usually 0) to the 95th percentile of the maximum
value observed for. each metric. The scoring criteria for
the genus/species-level, 300-organism subsample, which
were used for the biological assessments, are presented in
Table 4-2. Note that separate criteria were developed
(Table 4-2) based on least-impaired conditions in
Canastota Creek (for assessment of stations in that stream
Combines Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
31,
-------
32
Evaluating the Biological Effects of Combined Sewer Overflows in New York
-------
Oneida Lake
Canastota
Onondaqa Lake
Syracuse
Susquehanna
River
Miles
5 15 25 35
I I I I I I I I
Figure 4-1. State of New York. Rivers and streams sampled for the biological assessment of combined sewer overflow
effects, September 1993. \
and Harbor Brook) and in the Tioughnioga River (for
assessment of Onondaga Creek stations). The calculated
or enumerated values for each of the metrics are given in
Table4-3.
4.2.2 Canastota Creek at Canastota, New
York
4.2.2.1 Historical Information
The Canastota Creek watershed covers a drainage area of
approximately 8.5 square miles and includes Cowaselon
and Canaseroga Creeks. The drainage area encompasses
. Canastota, Lakeport, and agricultural lands. Canastota
Creek flows through the town of Canastota and joins
Cowaselon Creek on the northwest side of town. Before
the construction of the WWTP, sewage was discharged
directly into the lower part of Canastota Creek. At the time
of the initial biological survey of these streams (Preddice
1975), the WWTP discharge was directly into Cowaselon
Creek upstream of the Canastota Creek confluence.
A sample collected just downstream of the Main Street
(Canastota) bridge in 1975, comprised a relatively tolerant
macroinvertebrate assemblage (Preddice 1975) (Table 4-4).
Several of these groups are indicative of potential organic
enrichment; they were also found in low density. Other
organisms at this site were Cladophora (Chlorophycophyta
[green algae]) and some blue-green algae
(Cyanophyophyta), and several species of bottom-feeding
fishes (blacknose dace, longnose dace, creek chub, and
white sucker). In spite of the appearance of suitable
substrate quality and flow conditions, the low number of
benthic macroinvertebrates found, combined with their
relative tolerance, indicated a potential of simultaneous
toxic input and nutrient enrichment (Preddice 1975). This
assessment was considered consistent with the presence of
both green and blue-green algae. The upstream source of
toxicants was not determined; however, it was learned that
an herbicide, atrazine, had been used. At the time, atrazine
was considered to have only limited toxic effects on insects
(Weed Science Society 1974) and, therefore, was not
considered the source of the problem (Preddice 1975).
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
33
-------
Table 4-2 Scoring criteria developed for the benthic macroinvertebrate assemblage, 300-orgairiism subsample.
For ป description of the development of scoring criteria, see Section 2.3.1.
ammanmi I i n '"""
ACCCCCMCKJT
ASScooMtN I
SCORES
METRIC
1. Taxa Richness
2. HBI
3. Sc/{Sc+FB)x
100
4. EPT/(EPT+
Chir)x100
5. %ContDom.
Taxon
6. EPT Index
7. Shredders/ ,
Total x 100
8. H/TxIOO
9. Pinkham-
Pearson
10. QSI-Taxa
11.DIC-5
12. QSI-FFG
SCORING CRITERIA
0
2
4
6
Canastota Creek, Harbor Brook
s10
' 26.3
7.7-0
s21.5
45.9
3-0
2.2-0 .
271.4
2.3-0
13.3-0
s1
20.7-0
21-11
4.2-5.2
15.5
43.1-
21.6
30.6-
45.8
7-4
4.5-2.3
47.6-
71.3
4.7-2.4
26.7-
13.4
2
41.5-
20.8
32-22
2.1-4.1
23.3-
15.6
64.7-
43.2
15.3-
30.5
11-8
6.8-4.6
23.8-
47.5
7.1-4.8
40.1-
26.8
3
62.3-
41.6
2 33
0-2.0
223.4
264.8
0-15.2
212
26.9
0-23.7
22.7
240;2
24
262.4
0
2
Onondaga Creek,
*10
25.1
213.3
s22.9
217.7
4-0
3.7-0
271.4
2.0-0
7.8-0
sO
1.3.6-0
SSSSSSSSSSSSSSSSSSSi
21-11
3.4-5.0
26.7-
13.4
45.9
11.8-
17.6
9-5
7.5-3.8
47.6-
71.3
4.1-2.1
15.7-7.9
1
27.3-
13.7
4
Tioughniogiii
32-22
1.7-3.3
40.1-
.26.8 ,
68.9
5.9-1.7
14-10
4.3-7.6
23.8-
47.5
6.2-4.2
23.6-
15.8
2
41-27.4
6
River
233
0-1.6
240.2
" 269
0-5.8
215
211.4
0-23.7
26.3
223.7
23 .
241.1
It was also discovered that a sewage/stonnwater bypass
pipe was present in the channel. This pipe was acknowl-
edged as the probable source of nutrient loadings during
storm flow (Preddice 1975).
More recently, at another site downstream of the Main
Street bridge, Canastota Creek was found to be moderately
impacted (Bode et al. 1993). Samples taken in early
summer (19 June 1990) produced 24 percent midges
(Chironomidae) and 69 percent aquatic earthworms
(Oligochaeta), both of which are considered tolerant to
severe pollution including conventional toxics, eutrophica-
tion, and habitat degradation. No mayflies, stoneflies, or
caddisfljes (Ephemeroptera, Plecoptera, and Trichoptera,
respectively) were found, and the HBI fell in the "moderate
impact" category.
4.2.2.2 Sampling Station Description and Habitat Quality
Three sampling stations were selected on Canastota Creek
(Figure 4-2). The regional reference site for this stream
was located on Furnace Brook (Station CHR4). Habitat
assessment scores, along with measurements of dissolved
oxygen, temperature, and conductivity, are presented in
Table 4-5.
Furnace Brook, Station CHR4. This station was recom-
mended by NYDEC for the regional reference for both
Canastota Creek and Harbor Brook. The habitat quality
rated optimal in all parameters except riparian vegetative
zone width, which rated 15. The substrate was composed
of cobble and small boulders with well-developed riffles.
- The riparian vegetation was very good, and the banks were
stable. The habitat assessment score was 212. However, a
34
Evaluating the Biological Effects of Combined Sewer Overflows in New York
-------
i
o
o
10
0)
V)
m
in
to
O
o
o
X
2
"35
*
m
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0.
o ซ
o ^-
w
CO gs
o =
.. 0)
ป ฃ
CO ~
,0. ป
c O)
l!
g w
So
*-
.ฃ w
g ง
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g i
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ซJ= ฃ
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= ฃ
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v-
8
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1
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T-
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00
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Taxa richness
**!
1
CD
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in
0,
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iff
ffl
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8
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6
UJ,
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"*
g
S'
s.
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oi
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co>
1
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CD
> ^
CO
irj
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CD*
T-1'
^.s
oci
01
i
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o
in
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1
00"
2-
oT
r--
1
1
, T
X
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CD
g
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in
^
CO
s
s
in
o"
CO
ci
g
in
r-
d.
CO
oi
s.
CM
O>
JO,
(Shred^ot) x 100
c-
g
0
o
c?
CM
0
CO
s
O)
co
ss.
o
g
CO
CO
en
0
o -
^_^
en
CO
o
(Hydro/Trich)x100
CO
of
in
jo,
CO
JO,
co
g
tr
o"
Ci
g
25"
*"
CD
f^*
OJ
s.
cr
X
CB
Pinkham-Pearson in
CD
S
V-
JO
CO*
CO
si
en
S"
2"
a:
o"
of
ง
CM
If
in
CD,
in"
in
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2
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CO
0
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s
1
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CN"
CM
1
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6
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to
CM
m
ฃ"
in
in
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CC
ฃ7
00'
01
S
in
CO
CD
-------
Table 4-4 Primary taxonomic composition of benthic macroinvertebrate samples taken by Pwiddice
{1975}. Canastota Creek, Canastota, New York, 29 July 1975.
TAXON
Physa
Asellus
Lumbriddae
Tendepedidae
Heptagenfidae
Tricladida
Hirudinea
Elmldao
HIGHER LEVEL CATEGORY
Gastropoda: Physiclae
Isopoda: Asellidae
Oligochaeta
Diptera
Ephemeroptera
Turbellaria
Oligochaeta
Coleoptera
COMMON NAME::
snails
sowbugs
aquatic earthworms
true flies
mayflies
planarians (flatworms)
leeches
riffle beetles
hyperabundance of amphipods was found (nearly 76
percent of the 300-organism subsample was Gammarus);
therefore, this station was not used as a representative of
reference conditions. Furnace Brook was not used to
establish scoring criteria.
Canastota Creek, Station CC1 (upstream reference). The
station farthest upstream does not receive CSO input at or
above this location. At this location the stream is approxi-
mately 2.5 meters wide with a dense canopy cover and
variable bank stability. Where the samples were taken, the
banks were in relatively stable condition with little evidence
of accelerated erosion; however, areas of active bank
erosion were observed upstream. The riparian vegetative
zone on either side of the stream was less than 6 meters due
to human activity. The substrate available for benthic
fauna at this site consisted of a good mix of boulder and
cobble, and well-developed riffles were prevalent. How-
ever, there were some problems with sedimentation and
substrate embeddedness. The habitat assessment rating
score was 149 (Table 4-5).
Canastota Creek, Station CC2. This station was the first
station on Canastota Creek below CSO outfalls. Relative to
the upstream reference station, CC2 had a reduced canopy
cover, a predominantly sand and gravel bottom with a high
degree of embeddedness, and less well-defined riffles; The
stream here was approximately 3 meters wide and had
moderately unstable banks with very poor riparian vegeta-
tion zones. The habitat assessment rating score was 132
(Table 4-5).
Canastota Creek, Station CCS. Station CCS is behind the
Sewage Treatment Plant; the stream hi this area is approxi-
mately 3 meters wide. Sampling took place approximately
12 meters upstream from the agricultural ditch that enters
on one the side of the stream. The habitat structure at this
station was also more degraded than that of CC1. The
substrate consisted almost entirely of sand; there was
substantial sediment deposition and evidence of past
channelization. The riparian buffer zone and the condi-
tion of the banks were both scored very poor. The habitat
assessment rating score for this station was 92 (Table 4-5).
Overall, the best habitat quality on Caaastota Creek was
found at the upstream reference site, station CC1. The two
downstream stations both experienced degradation in .
channel characteristics and poor riparizm vegetative
protection. The individual components of the physical
habitat structure that were rated in the poor and marginal!
ranges, at both stations CC2 and CC3, were related to the
lack of riparian buffer zone and the high degree of
embeddedness. In addition, at CC3 the condition of the
banks and increase in sediment deposition related to erosion
were rated poor. Station CCS rated consistently lowest in
most habitat parameters, which is reflected hi the percent
comparability (66 percent) to the reference station. Habitat
condition should be considered degraded at station CCS;
habitat quality should not be limiting to the .biological
condition at Stations CC1 or CC2, despite some problems
atCC2.
4.2.2.3 Biological Assessments
The stations on Canastota Creek were assessed for the
RBPI as slightly to moderately impaired (CC1) and
moderately impaired (CC2, CCS). A further description of
this screening-level assessment and how it compares to the
more rigorous RBPEII assessment can be found in Section
5.1.
For biological assessments using CC1 as the reference site,
metric totals without paired metrics were used for percent
comparisons. The upstream (CC1) and middle (CC2)
stations were very similar in their biological condition, the
latter having the same assessment score as the former
(Table 4-3). However, more detailed interpretation of
individual metric values shows substantial differences in.
number of taxa. Twelve additional taxa were found at CC2,
eight of which were genera of the Chironomidae (Appendix
B), a group generally considered to be pollution-tolerant.
All of the additional midge genera have designated
36
Evaluating the Biological Effects of Combined Sewer Overflows in New York
-------
- Oneida Creek
Cowaselon
Creek
Canastota Creek
FLOW
Figure 4-2. Locations of sampling stations on Canastota Creek. STP = Sewage Treatmant Plant.
tolerance values of 5 or above, indicating their high
tolerance of or potential for positive response to pollution.
The high tolerance values caused an increase in the HBI.
There was also a higher proportion of Stenelmis (Co-
leoptera: Elmidae: riffle beetles) at CC2 than was seen
upstream. This might have been due to a combination of
increased growths of periphyton and filamentous green
algae responding to removal of some of the canopy
.(providing increased light), and upstream organic enrich-
ment;
Station CCS had habitat that was further degraded and a
biota that compared at 76 percent to that at the upstream-
, most site, substantiating what was seen at the upstream
stations. That is, there is likely some organic enrichment of
Canastota Creek occurring upstream of any CSO effects,
possibly from agricultural activities. Though none of the
three stations had excessively high values for the metric
"percent contribution of dominant taxon," samples from
each were dominated by the Hydropsychidae, often seen in
high numbers in organically enriched streams. The degree
of habitat degradation between CC1 and CC2 (11 percent
change) is less than that between CC2 and CC3 (30 percent
change), but both indicate either nonimpairment (CC2) or
only slight impairment. However, in the absence of a
suitable (nonimpaired or minimally impaired) regional
reference site for comparison, CC1 and CC2 should be
considered slightly to moderately impaired; CC3, moder-
ately impaired.
4.2.3 Harbor Brook in Syracuse, New York
4.2.3.1 Historical Information
Historical data on Harbor Brook (11.8 square miles drainage
area) are from NYDEC sampling at stations near Highway
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
37
-------
Table 4-5 Canastota Creek habitat assessment rating score.
- *^m --!;
HABITAT PARAMETERS
rn - Pttt
Substrate and
Instream Cover,
Channel
Morphology
Riparian
TOTAL SCORE
Physicochemtoal
Parameters
Instream Cover (Fish)
Epifaunal Substrate
Embeddedness
Velocity/Depth Regimes
Channel Alteration
Sediment Deposition
Frequency of Riffles
Channel Flow Status
Conditions of Banks
Bank Vegetative Protection
Grazing or Other Disruptive Pressure
Riparian Vegetative Zone Width (Least
Buffered Side)
Temp (ฐC)
PH
Conductivity
SCORES
Canastota Creek Sampling Stations
CC1
12
16
13
18
17
4
19
13
12
15
8
,2
149
12
8
16.38
10.3
CC2
13
11
8
12
10
10
12
15
10
14
14
3
132
11.8
8.23
15.91
8.5
CCS
8
10
7
- 7
14
5
8
8
5
9
10
1
92
14.2
8.88
b
8.1
CHRi*
19
19
16
19
16
18
19
19
18
17
17
15
212
10.5
8
b
9.8
Furnace Brook, regional reference site, not used in biological assessments due to impairment.
* Lack of physteochemteal data is due to equipment failure. '
173 at Split Rock and another station approximately 0.8
kilometer upstream from the mouth into Onondaga Lake
(Bode et aL 1989). The upstream station at Split Rock is
approximately 1.5 miles south (upstream) of HB1 of this
study. At the Split Rock, station the benthic
mactoinvertebrate assemblage was assessed as moderately
impacted. This stream is known to be intermittent (Bode et
al. 1989), and the abundance of taxa tolerant to temporary
desiccation influenced this assessment Bode et al. stated that
the chemical water quality might actually have been
nonimpacted.
The second station assessed by Bode et al. was located
between HB2 and HB3 (Bode et al. 1989). The channelized
and degraded habitat produced a sample made up mostly of
Chironomidae, Oligochaeta, Hirudinea, and Amphipoda.
(midges, earthworms, leeches, and scud, respectively). All
four parameters rated as poor (species richness, 8; biotic
index, 9.7; EFT value, 0; and percent model affinity, 15) and
resulted in an assessment of "severely impacted." Descrip-
tions of these parameters are presented in Bode et al. (1989,
1993) and Bode and Novack (1995).
i
4T2.3.2 Sampling Station Description and Habitat Quality
Assessments
, (,
Three sampling stations were selected on Harbor Brook
(Figure 4-3). It was not possible, however, to include HB3
in the biological assessments due to the deep, soft bottom,
which is not suitable for a wadable kick net sample. T.ne
length of Harbor Brook within this study was completely t
channelized. Approximately 150 meters downstream from
the farthest upstream station (HB1) is a flow dissipator,
through which water enters an emerijent-macrophyte-filled
retention basin. Further downstream, the water is subjected
38
Evaluating the Biological Effects of Combined Siswer Overflows in New York
-------
Onondaga Lake
Interstate 81
HB2
HB1
Harbor
Brook
]
Furnace Brook
OC2
CHR4
Onondaga Creek
OC1
FLOW
0 24 6 8
Miles II r-H 1
Figure 4-3. Locations of sampling stations on Onondaga Creek, Harbor Brook, and Furnace Brook.
to a flow splitter; the flow then enters a cement- and rock-
v sided channel; this type of channel with armored sides con-
tinues for the rest of the length of Harbor Brook. For some
intermediate distance in the study length, the stream has .
been closed on the top,, making it essentially a subsurface
channel. The second and third sampling stations (HB2 and
HB3, respectively) were located just downstream from
where the channel was no longer covered; that is, in the
section between State Fair Boulevard and Hiawatha Street.
Thus, there is a major difference in habitat quality between
the sampling site farthest upstream (HB1) and the two
downstream sites, whigh should be recalled in these com-
parisons. The regional reference site for this stream (Fur-
nace Brook [Station CHR4]) was dropped as the regional
reference site; therefore the upstream station on Canastota
Creek (CCi) was used for reference. Habitat assessment
scores, along with measurements of dissolved oxygen, tem-
perature, and conductivity, are presented in Table 4-6.
Harbor Brook, Station HB1. This station was located
approximately 150 meters upstream of the flow dissipator
and about 350 meters upstream of Velasko Road. The stream
was approximately 2.5 meters wide, and the substrate was ,
composed of cobble and gravel with very little
embeddedness. The frequency of riffles was optimal as was
the condition of the banks and the riparian vegetative
protection. Even though the stream was located among
relative heavy urbanization, its physical quality was very
good. This site scored high on the habitat assessment at 182.
Harbor Brook, Station HB2. HB2 was located approxi-
mately 5 meters downstream of the State Fair Boulevard
bridge off Hiawatha Street. The stream was completely
channelized with no riffles and very slow-moving water;
the width was approximately 2 meters. The substrate at
this station was mostly sand with a little gravel. The only
parameters scored above poor or marginal were channel
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
39
-------
Table 4-6 Harbor Brook habitat assessment scores
HffPiiiiiiBil Iritiff'"1.!. * i "i ' '"'"TmTnF***^*"**
=====
HABITAT PARAMETERS
/n . on\
Substrate and
Instraam Cover
Channel-
Morphology
Riparian
TOTAL SCORE
Physicochemical
Parameters
v ซป*/
Instream Cover (Fish)
Epifaunal Substrate
Embeddedness
Velocity/Depth Regimes
Channel Alteration
Sediment Deposition
Frequency of Riffles
Channel Flow Status
Conditions of Banks
Bank Vegetative Protection
Grazing or Other Disruptive Pressure
Riparian Vegetative Zone Width (Least
Buffered Side)
Temp(ฐC)
PH
Conductivity
SCORES
Harbor Brook Sampling Stations
HB1
16
19
12
18
13
17
17
12
17
18
18
5
182
13
7.95
b
9
=====
HB2
2
1
, 5
1
1
1
1
18
, 18
7
1
1
57
12.5
7.86
b
7.3
===:
HB3
2
0
1
1
1
1
1
19
19
10!
1
1
54
ti
b
b
b
-3=
CHR4*
19
19
16
19
16
18
19
. 19
18
17
17
15
212
10.5
8
__b
9.8
========1
Furnace Brook, regional reference site, not used in biological assessments due to. impairment
ป Uck of physJcochemteal data is due to equipment failure.,
flow status and condition of banks; the .banks were ar-
mored. This station had severely degraded habitat and
scored only 57.
Harbor Brook, Station HB3. This station, located about 5
meters upstream of the Hiawatha Street bridge, was
extremely degraded. AU habitat parameters scored in the
poor range except for the channel flow status and condition
of banks (due to the armored sides). The substrate at this
site was a grayish-black muck; the stream was too deep
here to be considered "wadable" for sampling. The habitat
assessment score for HB3 was 54.
The poor habitat at both HB2 and HB3 can be considered
to be extremely limiting to the biological condition of this
stream.
4.2.3.3 Biological Assessments
Screening-level assessments (RBPI) indicate moderate
(HB1) to severe (HB2, HB3) impairment on Harbor Brook.
Comparisons'between the screening-level assessment and
the RBPIII assessment are discussed in Section 5.1.
Because of the extreme habitat alteration, samples could
not be taken from what was to be the downstream-most
station (HB3). As discussed in Section 4.2.2.2, the regional
reference site for Harbor Brook (Furnace Creek) was
dropped as a baseline comparison due to biological impair-
ment; station CC1 was used for reference. HB1 and HB2
scored 41 percent and 17 percent comparability, respec-
tively, to the upstream site on Canastota Creek (CC1). The
upstream station (HB1) had a metric score for "percent
contribution of dominant taxon" of 63.9 that represented
Evaluating the Biological Effects of Combined Ssiwer Overflows in New York
-------
246 Gammarus (Crustacea: Amphipoda: Gammaridae); the
second most dominant, comprising another 15 percent of
the individuals, was of the caddisfly family
Hydropsychidae (Trichoptera: Cheumatopsyche,
. Hydropsyche). Both of these groups are considered to be
tolerant to some level of habitat degradation, positively
responsive to nutrient enrichment (Hydropsychidae,
Gammarus), and tolerant to some potentially toxic inputs
(Gammarus). Compared to CC1, this.station had a lower
taxa richness, higher HBI, higher percent dominant taxon,
and lower EPT index. Each shows the expected direction
of the metric value change when exposed to physical and
chemical degradation. .
The downstream station (HB2) had completely different
habitat and flow regime. Here, the two most dominant taxa
were Chironomus (Diptera: Chironomidae) (60 percent,
194 individuals of 385 total) and Gammarus (66 individu-
als). The genus Chironomus is one of the taxa more
tolerant of chemical pollution and habitat degradation.
Also found were 13 specimens of a cyclopoid copepod
(Crustacea: Cppepoda) normally found in lakes and
reservoirs. At this station, water was deep and slow-
moving, perhaps making it suitable for copepods. There
were six different genera of Oligochaeta (aquatic earth-
worms) that are as a whole considered to be tolerant of a
range of severity in habitat degradation. The HBI was 8.4
in contrast to the 5.7 and 4.5 of HBI and CC1, respectively.
This is indicative of a sample dominated by individuals of
pollution-tolerant taxa.
Even though the habitat and most of the benthic metrics
differed substantially between HBI and HB2, the "taxa .
richness" of the stations was nearly identical. This is an
illustration of why single measurement parameters should
not be relied upon for performing biological assessments;
rather, single parameters should be used to interpret
overall multimetric assessment scores and aid in deter-
mining causes of impairment. Station HBI should be
considered moderately impaired and HB2 severely
impaired.
4.2.4 Onondaga Creek in Syracuse, New
York
4.2.4.1 Historical Information
The Onondaga Creek drainage covers approximately 111
square miles. It traverses rural agricultural communities, a
Native American reservation, and downtown Syracuse.
Bode et al. (1989) sampled Onondaga Creek at two
locations, one about 1 mile upstream of Onondaga Lake
and the other near Cardiff just off Webster Road and about
15 miles upstream of the first site. The site upstream of
Onondaga Lake was assessed as "severely impacted" in
1989 (Bode et al. 1989),and 1990 (Bode et al. 1993). In
1993 Bode et al. found only Chironomidae and
Oligochaeta, both considered to be strongly pollution-
tolerant. Other characteristics of the sample were eight
species (poor), a biotic index of 9.7 (poor)* EPT value 0 .
(poor), and percent model affinity 15 percent (poor).
Tissue analysis of caddisflies collected at the site indicated
no elevated levels of metals above background levels;
crayfish had elevated levels of the PCB aroclor 1254 (0.42
|jg/g, which is below the U.S. Food and Drug Administra-
tion action level of 2 ppm). Parameters of concern in the
water column were aluminum, iron, lead, mercury, zinc,
dissolved solids, and both total and fecal coliform; manga-
nese was borderline. Bottom sediments contained levels of
copper, zinc, lead, mercury, PCBs, and DDE above back-
ground levels but below assessment criteria levels. Toxicity
testing indicated that significant mortality and reproductive
impairment occurred in assays during 1990.
It should also be noted that 17 miles of Onondaga Creek
upstream of Syracuse are affected by mud boils. These
geomorphic reactions to excessive groundwater drawdown
result in periodic episodes of hyperturbidity. Also, sections
of this creek have been closed to fishing due to brine
discharges and mining operations. In spite of the
hyperturbidity, the macroinvertebrate community at the
NYDEC upstream station located hi Cardiff was found to
be in "slightly impacted" condition hi 1989 and 1990,
with 24 species, a biotic index of 6, EPT value of 4, and 68
percent model affinity (Bode et al. 1993).
4.2.4.2 Sampling Station Descriptions and Habitat
Quality.
Tioughnioga River, West Branch, Station OC4. The
Tioughnioga River was selected as the regional reference for
Onondaga Creek (Figure 4-4). This station was located in
Homer, New York, just downstream of the Highway 11 bridge
and upstream from potential backwater influence resulting
from a slow segment of the river that probably widened during
construction of Interstate 81. Habitat quality was rated optimal
for most of the parameters. The substrate was composed of
cobble, and riffles were well-developed and prevalent The
Ibwest habitat score was for the riparian buffer zone width.
The overall habitat assessment score was 191 (Table 4-7).
Habitat quality would not limit the biological communities at
this regional reference site.
Three sampling stations were selected on Onondaga Creek
(Figure 4-3). The entire length of Onondaga Creek
downstream of the Onondaga Tribal Reservation is
channelized, and the state of the streambanks differs at all
three stations. At the upstream station, the banks are
mown and grassy; at the middle station, they are armored;
and at the farthest'downstream station, they consist of
rubble and debris with some weedy vegetation. Habitat
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
41
-------
Tioughnioga River
Susquehanna River
Figure 4-4. Location of sampling station on the Tioughnioga River (West Branch).
assessment scores along with measurements of dissolved
oxygen, temperature, and conductivity are presented in
Table 4-7.
Onondaga Creek, Station OC1. Station OC1 was estimated
as approximately 50 meters wide and is channelized. This
station was used as the upstream reference station because it
was located above any CSO outfalls. The substrate was
composed of mainly gravel with a high degree of
embeddedness, there were no fast water riffles present at this
site, and the velocity/depth regime was rated "very poor." The
habitat variability at this site was minimal. The banks were
stable but very little riparian buffer existed. According to
DEC staff water was unusually clear at this station (S. Cook,
personal communication, September 1993), at the time of
sampling. The habitat assessment score was 86.
Onondaga Creek, Station OC2. The stream at this station
was approximately 8 meters wide and was completely
channelized with concrete armored sides. The substrate
was composed of cobble with intermittent riffles; there was
little embeddedness and sediment deposition. There was
no riparian vegetative buffer zone, but the condition (i.e.,
stability) of the banks was rated optiinid due to the armored
sides. The habitat assessment score wits 114.
Onondaga Creek, Station OC3. This station was located
approximately 0.8 kilometer upstream of Onondaga Lake.
The stream was approximately 10 meters wide with cobble
substrate and intermittent, well-developed riffles. Riparian
zone scores were the lowest rated at this station, which had
little to no buffer zone and little bank vegetative protec-
tion. The overall habitat assessment score was 118.
The upstream reference station, OC1, was rated the poorest in
the habitat assessment The habitat at tills station would
seem to be the limiting factor for the development of the bio-
logical community. Although the bank vegetative stability at
this site was rated in the optimal range, upstream erosion
caused a marked increase in embeddedness and sediment
deposition, which decreases the amount and variety of epifau-
nal substrate habitat available for colonization. The habitat
assessments for the two CSO receiving stations were scored
higher than that for OC1 hi all mstreana habitat characteris-
tics because there was a lack of apparent sedimentation and
embeddedness. In spite of the absolute channelization with
42
Evaluating the Biological Effects of Combined Sewer Overflows in New York
-------
Table 4-7 Onondaga Creek habitat assessment scores.
HABITAT PARAMETERS
. (0-20)
Substrate and
Instream Cover
Channel-
Morphology
Riparian
TOTAL SCORE
Physicochemical
Parameters
Instream Cover (Fish)
Epifaunal Substrate
Embeddedness
Velocity/Depth Regimes
Channel Alteration
Sediment Deposition
Frequency of Riffles
Channel Flow Status
Conditions of Banks
Bank Vegetative Protection
Grazing or Other Disruptive Pressure
Riparian Vegetative Zone Width (Least
Buffered Side) - .
Temp(ฐC)
pH
Conductivity
DO
SCORES
Onondaga Creek Sampling Stations
OC1
5
7
3
2
1
6
2
18
19
18
4
1
' 86
12.5
8.14
_it>
10.6
OC2
10
18
17
.7
1
16
5
17
19
1
3
0
114
15
7.85
b
9.8
OC3
11
16
11
10
3
13
8
16
16
7
6
1
118
13.5
7.89
b
8.3
OC4*
16
19
15
16
13
16
19
18
, 19
17
15
8
191
13
8.03
b
10
* Tioughnioga River, regional reference site.
" Lack of physicochemical data is due to equipment failure.
mortared block banks, sufficient stands of older deciduous
- trees were present to supply substantial leaf litter and woody
debris to the channel.
4.2.4.3 Biological Assessments
Screening level assessments (RBPI) for Onondaga Creek
indicated moderate (OC1) to moderate-severe (OC2, OC3)
impairment; the regional reference site on the Tioughnioga
River was screened as having slight impairment Further
comparisons between the screening and rigorous-assess-
ments is discussed in Section S.I.
This creek has been channelized along most of its
length; for each of the three sites sampled in this study,
characteristics of the channelization differed markedly
and might temper conclusions. The upstream-most
station, OC1, is in a section of the channel that is very
wide and shallow and produced 39 taxa (in essence
identical to the 40 from the Tioughnioga River, the
regional reference site). Of these 39, however, 24. were
genera of Chironomidae (midges), considered to be an
overall pollution-tolerant taxon. This finding is
reflected in its relatively high HBI of 6.1, contrasted to
the 4.4 of the Tioughnioga site (OC4). Although
Cryptochironomus (Chironomidae) accounts for the 11
percent dominant taxon (29 individuals), another 3
genera produced 23, 22, and 19 individuals.
Hydropsyche and Limnodrilus (Oligochaeta: Tubificidae)
were also dominant in these samples; they are both
considered relatively pollution tolerant and often
respond positively to organic nutrients. Station OC1
Combined Sewer Overflows and the Mulnmetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
43,
-------
was calculated as being 63 percent comparable to the
regional reference site and should be considered to have
moderate impairment
Station OC2, the middle station on Onondaga Creek and the
first to receive CSO inputs, produced a sample that seemed to
have a biological condition slightly improved over that seen at
OC1. This is due primarily to a higher EPT-Chkonomidae ra-
tio, higher percentage of shredders in the sample, and higher
QSI-Taxa (Table 4-3). However, as with OC1, the dominant
taxa was comprised of Hydropsychidae and Chironomidae.
This station was 70 percent comparable to the regional refer-
ence and should be considered to have moderate impairment
The farthest downstream station, OC3, was rated as 41 percent
comparable to the regional reference site. It produced a .
sample that was dominated primarily by Nais and Ophidonais
(Oligochaeta: Naididae) (24 percent and 20 percent of total
sample, respectively), and Cricotopus (Diptera:
Chrionomidae) (12 percent of total sample). Also represented
in a larger proportion than other taxa in this sample were
DM^es/a(Turbellaria)andHydracaririas|[). (Acari). All of
these groups are considered to be tolerant to some levels of
physical habitat degradation and toxicant input and they often
respond positively to increased nutrient loads. Station OC3
should be considered as severely impaind. Heavy urbaniza-
tion effects make it difficult to isolate CSO effects in
Onondaga Creek. However, excessive algal growth and high
numbers of tolerant taxa suggest that sul>stantial organic
enrichment had occurred; the nutrient loading had likely
originated with the CSOs.
44
Evaluating the Biological Effects of Combined Sewer Overflows in New York
-------
5
Evaluation of Method
T. . .. - .
tie purpose of this chapter is to address issues related
to method rigor and the effect of different levels of
rigor oh assessment results. A critical factor in selecting
the level of application of RBPs is the availability of tiers.
RBPI, II, and III represent three levels of intensity with
RBPI being the most rapid and least rigorous (Plafkin et
al. 1989). RBPI is based only on field observation of
benthic invertebrates without any standardized sampling
effort or index/metric calculations and interpretations.
RBPII and RBPIII employ standardized sampling gear and
effort, field and laboratory taxonomic identification,
respectively, and subsampling. Decisions on which of
these protocols to use are usually focused on some combi-
nation of these components in the context of protocol
sensitivity and resource availability (Ferraro et al. 1989;
Ferrarp and Cole 1992). The analyses below are designed
to evaluate the effects of subsample size and taxonomic
level on metric performance and overall assessment
results; these comparisons were conducted only for the
New York case study. Though the results here might
produce some conclusions on methods, it should be
realized that these comparisons Will not necessarily apply
to other regions of the country.
5.1 Adequacy of Screening Level
(Rapid Bioassessment
Protocol)
RBPI screening level assessments are based on the relative
abundance of organisms collected at a site. Collection of
macroinvertebrates consists of turning over rocks (hand
picking) and/or taking qualitative samples with a dipnet.
These samples are supplemented by field examinations of
periphyton, macrophytes, slimes, and fish which provide
additional information for determining presence or absence of
degradation. The variety of organisms (taxa richness), their
relative tolerance levels, and factors observed for other biota,
are then used to determine if the site is impaired. The
adequacy of this approach relies on three basic factors:
(1) that die assessment needed provides only the presence or
absence of degradation, not detailed information as to the
nature and cause of the degradation, (2) that the individual
performing the assessment has a strong familiarity with
aquatic invertebrate taxonomy generally at family-level, and
(3) that the individual has knowledge of or access to informa-
tion on relative pollution tolerance and functional feeding
group associations of different aquatic biota.
The assessments produced by this screening level effort are
presented in Table 5-1. These results did show sampling
stations where there was unpaired biological condition
(Table 5-1). Most of the screening level assessments fell
within the range of the higher level assessment (Table 5-2).
.This screening level of assessment did underestimate
impairment on one occasion, station CHR4, the initial
regional reference site for Canastota and Harbor Brook mat
was dropped after further assessment. The screening level
assessment notes the relative abundance and variety of
organisms observed. The categories of abundance are:
Rare
Common
Abundant -
Dominant
<3
3-9
>50 (estimate).
Initial assessment of station CHR4 showed a good variety of
sensitive organisms (e.g., Plecoptera, Ephemeroptera- ,
dominant). However, with such a rating system, the hyper-
abundant Amphipola was given the same rating, i.e.,
dominant Further evaluation of CHR4 using RBPDI level
assessment revealed that Gammarus (Amphipoda:
Gammaridae) comprised -76 percent of the sample thus
indicating impairment of the aquatic community. Overall,
however, the RBPI is an adequate and cost-effective screening
level assessment.
5.2 Metric Performance with
Variable Methods
The different assessment levels of RBPs provide a means for
agencies to tailor their biological monitoring programs to suit
Combined Sewer Overflows and the Multimetric Evaluation ofTheir Biological Effects: Case Studies in Ohio and New York
45
-------
Table S-1 Narrative screening-level assessments (RBPI) of 10 study stations in New York State
performed 20-23 September 1993. Use of narratives for impairment is based on the following
categories of increasing biological degradation or impairment: minimal-slight-moderate-severe.
- -- ' . .....I" - ...^ -- . .J-g=5!H"i!!LLL-L '""
STATION
IMPAIRMENT
REASON(S) FOR ASSESSMENT
CC1
slight to
moderate
1. Dominance of relatively tolerant Hydropsychidae (net-spinning
caddisflies) and Elmidae (riffle beetles). 2. Heavy embeddedrtess of
substrate, some upstream bank instability. 3. Narrow buffer zone, both
sides. 4. Potential organic enrichment from agricultural operations.
CC2
moderate
1. Dominance of Hydropsychidae and Elmidae (both relatively tolerant);
abundant Oligochaeta (aquatic earthworms). 2. Substrate almost
completely sand and some small gravel. 3. Considerable upstream
bank instability. 4. Removal of canopy on one side.
5. Abundant growths of blue-green and filamentous green algae on
substrate. 6. Habitat degradation and organic enrichment.
CC3
moderate
1. Dominance of Hydropsychidae and Elmidae; Oligochaeta and
Chironomidae (midges) common. 2. Substrate almost completely
composed of sand and small gravel. 3. Severe bank instability. 4.
Narrow buffer zones on both sides; agricultural fields within 5-7 meters
on both sides. 5. Habitat degradation, organic enrichment, potential
highway and agricultural runoff problems. . - ______
HB1
moderate
1. Dominance of Amphipoda (scud), Chironomidae and
Hydropsychidae, all relatively tolerant. 2. Some embeddedness as
evidence of upstream erosion. 3; Narrow vegetated buffer zone, both
sides; little or no canopy cover. 4. Abundant growths of filamentous
green and'blue-green algae, and mosses. 5. Habitat degradation,
organic enrichment, potential toxicants. '
HB2
severe
1. Dominance of Amphipoda and Chironomidae, both considered
relatively tolerant; Oligochaeta and Physidae abundant. 2. Copepoda,
normally inhabiting standing waters, abundant. 3. Extreme habitat
modification, channelized, stone walls, very low current velocity, deep,
no riffles. 4. Habitat degradation, organic enrichment, potential
toxicants.
HB3
severe
1: Dominance of Gastropoda (probably physidae), Chironomidae, and
Hirundinea, all considered tolerant. 2. Extreme habitat modification,
channelized, stone walls, low current velocity, deep, no riffles,, silty/muck
bottom with macrophytes. 3. Habitat degradation, organic enrichment,
potential toxicants.
CHR4
minimal
1. Hyper-dominance of Amphipoda outweighed by considerable
diversity of taxa recognized as relatively pollution-sensitive including
Ephemeroptera (mayflies), Plecoptera (stonefiies), and Trichoptera
(caddisflies) (several families of the latter). 2. High-gradient, no
upstream habitat degradation/modification. 3. Dominant growths of
epilithic mosses and some filamentous green algae, potential for minor
organic enrichment. '
OC1
moderate
1. Dominance of Oligochaeta and Chironomidae, both relatively tolerant
of both physical and chemical disturbances. 2. Ephemeroptera,
Plecoptera, and Coleoptera, each with a mixture of tolerant and
intolerant species, considered common. 3. Channelized, uniform
habitat, embedded substrate, lack of riparian vegetation. 4. Potential
organic enrichment.
Evaluation of Method Variation
-------
Table 5-1 (continued).
STATION
IMPAIRMENT
REASON(S) FOR ASSESSMENT
OC2
moderate to
severe
1. Dominance of Hydropsychidae, exhibits strongly positive response to
organic enrichment and tolerance to some physical degradation. 2.
Arhphipoda, Oligochaeta, and Chironomidae considered abundant; all
are tolerant. 3. Channelized with mortared stone walls, and
considerable accumulation of gravel and cobble; minimal riparian
vegetation. 4. Likely receiving considerable organic inputs.
OC3
moderate to
severe
1. Dominance of Oligochaeta. 2. Planaria, Hirudinea, Amphipoda,
Hydropsychidae, and Chironomidae considered abundant-all pollution-
tolerant forms. 3. Channelized, very narrow riparian zone, heavy urban
development on both sides, much coarse human trash and other debris.
4. Strong sewage odor. 5. Likely receiving heavy organic inputs
combined with other urban runoff.
OC4
slight
1. Dominance of Trichoptera (several families) and Elmidae; some sub-
taxa can be positively responsive to organic enrichment. 2.
Hydracarina, Ephemeroptera (several families), and Chironomidae
considered abundant; some taxa are sensitive, others are tolerant. 3.
Good substrate diversity and riparian vegetation with canopy.
4. Some potential for asphalt runoff and a mixture of slight organic
enrichment combined with low-level toxicants. .
their needs. RBPI is used as an initial screening level
assessment for many sites. If an impaired biological condi-
tion is noted, further assessment may be carried out with
RBPn (family level taxonomy) or RBPm (genus/species level
taxonomy). The study was designed to compare results from
RBPn with RBPDJ. RBPFI requires specimen identification
no finer than to family level, whereas RBPDJ uses "the lowest
practical taxonomic level" (Plafkin et al. 1989), generally
genus or species level. Therefore, to address the questions
related to level of taxonomic identification, two datasets, one
based on family-level taxonomy and one based on genus/
species level, were needed. Results received from the
laboratory were generally at the genus or species level
(Appendix B). For a family-level dataset, taxa were com-
bined under the family name and the number of individuals
for each family was summed.
In order to evaluate sample size, it was necessary to calculate
metrics and develop scoring criteria based on both the 100-
organism and 300-organism subsamples. Data sets represent-
ing the latter were obtained by combining the data from 100-
and 200-organism subsamples for each sampling station.
Metric values calculated based on 300-organism subsamples
with genus/species-level taxonomy are presented in Table 4-3.
The metric values to which these are compared are based on
(1) family-level identification of lOO^organism subsamples
(Table 5-3) and (2) genus-level identification of 100-organ-
ism subsamples (Table 5-4).
5.2.1 Taxonomic Level Effects on Metric
Performance
The level of taxonomy used for a biological assessment
depends on the program objectives and resources. Biologi-
cal assessment results may not vary substantially between
family versus genus/species level taxonomy, howeyer,
interpretation of results may be problematic at the family
(or higher) level. If broad-scale status analyses are desired
for a large number of sites, RBPn assessment level may be
adequate. If, for example, causal relationships need to be
identified, RBPIII would be a better alternative potentially
giving greater sensitivity.
Using the metric values calculated on.lOO-organism
subsamples, comparisons of the effect of taxonomic level
were made based on (1) performance of single metrics and
(2) total bioassessment score. For both, correlation
scatterplots were developed that illustrate the relationship
between these measures at a single sampling station when
differential taxonomic resolution is used. At the family
level of identification, we would expect a smaller number
of groupings with a larger number of individuals than is
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
47
-------
Table 5-2 Comparison of biological assessments between RBPI and RBPIII
no further assessment was conducted on this site due to severe habitat alterations.
expected with genus/species-level taxonomy. Perfect
(1:1) agreement between the metric values at a single
station with different taxonomic levels will be reflected
by a point lying on the diagonal. Conversely, the more a
point is removed from the line, the greater is the
disagreement between treatments. In cases where there
seemed to be a non-trivial difference between the two
treatments, a Spearman rank correlation was used for
confirmation. The Spearman rank correlation provides a
measure of how similar the rank order is between twb
ordered lists. For example, if the rank order is A>B>C
for both treatments, the results would give a high R and
low p-value for the Spearman's test.
Alternatively, if the order is A>B>C for one treatment and
OB>A for the other, we would see a low R and a high re-
value. The interpretations between the two treatments could
be very different This test provides one indication of whether
differences in treatments will cause differences in interpreta-
tion of results, that is, relative station, condition.
Total Bioassessment Score. There was no difference in
total aggregated metric score between the two taxonomic
levels (Figure 5-1) when comparing station rank orders
(Spearman rank correlation, R=0.94, p=&0001).
Metric L Taxa Richness. This metric had a value range of 8
to 16 among stations when based on family-level identifica-
tions; the value range broadened to 8 to 31 when based on
genus/species-level identification.-When compared within
each station (Figure 5-2), the expected relationship of higher
number of taxa for finer taxonomic resolution was observed. ,
For those stations which are in more degraded condition,
there was generally a lower magnitude of increase of taxa
when identifications were made to the genus/species level.
This may illustrate potential partial redundancy with some
other metrics (e.g., percent contribution of dominant taxon,
HBI, Hydropsychidae/Total Trichoptera). That is, when
examining a benthic community at a degraded site, there is
often a dominance by few taxa, sometimes one or two. to
those cases, the one or two dominant taxa. are usually ones
with higher tolerance values (as in the Hilsenhoff scheme),
thus translating into a higher HBI value (see Metric 2).
Metric 2. .Hilsenhoff Biotic Index. Most stations showed
little effect of taxonomic levels. However, the HBI is strongly
reliant on tolerance values used hi its calculation. In some
cases, tolerance values were not available for the different; taxa
at either genus or family level since they are primarily
developed for species. In general, however, the largest
changes hi calculated values were seen; for the stations that
were in the worst condition overall, with higher HBI valu.es
resulting from a more specific taxonomy (Figure 5-3).
Metric 3. Scrapers-Filterer Collectors Ratio. These metric
values exhibited large changes when calculated on more
specific taxonomic levels. At the family level of identifica-
tion, the range of values was 0 to 66.7 (Jable 5-3), whereas at
the genus/species level it was 0 to 52.3 (Table 5-4). Interpreta-
tion of this metric is sensitive to two factors: (1) rarity of one
of the two functional feeding groups in a sample and (2) in-
creased uncertainty associated with assigning feeding
Evaluation of Method Variation
-------
Table 5-3 Family-level metric values calculated from 100-organism subsamples. Bioassessment
scores (in parentheses) are derived by comparing metric values to scoring criteria.
METRIC
1. Taxa richness
2. HBI
3. Scr/(Scr+Fc) x
100
4. EPT/(EPT+Chir)
x100
5. % Contr. Dom.
Taxon
6. EPT index -
7. (Shred/Tot) x
100
8. (Hydro/Trteh) x
100
9. Pinkham-
Pearson index
10. QSITaxxlOO
11. DIC-5
12. QSI-FFG x
100
Total (with paired)
metrics
Biology (with paired)
% comparison to
reference
Total (without
paired) metrics
Biology (without
paired) %
comparison to
reference
Habitat Score
Habitat %
comparison to
reference
CC1
14(4)
4.8(0)
36.6(6)
75.9(6)
30.5(4)
7(4)
6.8(6)
92.3(0)
UR(6)
UR(6)
UR(6)
; UR(6)
50
26
139
"
GC2
16(6)
5.5(0)
31.9(6)
59.2(6)
34.7(2)
. 5(2)
5.5(6)
97.9(0)
6.4(6)
73(6)
3(4)
85.6(6)
50
100
28
108
132
95
CCS
11(4)
5.2(0)
22.6(4)
88.2(6)
59.6(0)
3(2)
1.8(2)
100(0)
2.7(2)
64(6)
5(6)
73.7(6)
38
76
18
69
92
66
HB1
9(4)
4.6(2)
0(0)'
69J7(6)
70.1(0),
3(2)
0(0)e
95.2(0)
2(2)
16(0)
2(2)
49.7(4)
22
44
14
54
182
131
HB2
7(4)
,6.3(0)
0(0)"
0(0)
62.4(0)
0(0)
0(0)c
0(6)d
0.1(0)
1(0)
1(0)
27.6(2)
12
24
10
20
57
41
OC4
15(6)
4.7(2)
51.6(4)
86.4(6)
21.3(4)
8(4)
.1.1(4)
62.5(2)
RR(6)
RR(6)
RR(6)
RR(6)
56
"
32
191
OC1
. 10(4)
6.3(0)
25.0(2)
30.5(2)
49.5(0)
4(2).
f 0(0)
95.5(0) '
4.6(6)
\
42(6)
4.0(6)
53.7(6)
34
61
10
31
'86
45
OC2
9(2)
5.5(0)
8.6(0)
60.9(4)
43.1(0)
1(0)
0.8(4)
100(0)
4.7(6)
46(6)
4.0(6)
66.6(6)
34
61
10
31
114
60
OC3
10(4)
6.8(0)
66.7(6)
3.6(0)
40.2(0)
1(0)
0(0).
100(0)
1.0(0)
18(2)
2(2)
31.1(2)
16
28
10
31
118
62
UR = Upstream Reference; RR = Regional Reference;
No scrapers
" No scrapers or fitterer-collectors .
c No shredders
' No Trichoptera
CC1 also served as reference for naroor orooK, see page 4-11 ror junner aiscussion.
designations, which are usually assigned to species, to higher
taxonomic levels. The is because (1) many invertebrate taxa
are poorly known and (2) some taxa are known to shift
feeding behavior upon entering subsequent developmental life
stages.
Metric 4. EPT-Chironomidae Ratio: There is no effect on this *
metric since it is based on the number of individuals in these,
taxonomic groups (family and order, not genus/species).
Metric 5. Percent Contribution of Dominant Taxon. When
taxonomic groups are split {as accomplished by more specific
taxonomy), there are fewer individuals representative of each
of the subgroups and an overall lower contribution, to sample
composition. In sites considered to be in better condition,
values for this metric would thus be expected to substantially
decrease with more specific levels of taxonomy. However,
this expectation was not consistent with some of the results
(Table 5-4, Figure 5-4). Station OC4, the regional reference
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
49
-------
Table 5-4 Genua/specles-level metric values calculated from 100-organism subsamptes.
Bioassossment scores (in parentheses) are derived by comparing metric values to scoring criteria.
METRIC
1. Taxa richness
2. HBt
3. Scr/(ScH-Fc) x 100
4. EPT/(EPT+Chir) x
100
5. %Contr. Dom.
Taxon
6. EPT Index
7. (Shred/Tot) x 100
8. (Hvdromich)xlOO
9. Pinkham-Pearson
Index
10. QSITaxxlOO
11. DIC-5
12. QSI-FFQ x 100
Total (with paired)
metrics
Biology (with paired) %
comparison to
reference
Total (without paired)
metrics
Biology (without paired)
% comparison to
reference
Habitat score
Habitat % comparison
CC1
24(4)
4.4(2).
36.7(6)
75.9(6)
27.5(4)
9(6)
9.3(6h
92.3(0)
UR(6)
UR(6)
UR(6)
UR(6)
58
48
' 34
139
-
CC2
31(6)
5.2(2)
21.7(4)
59.2(4)
13.1(6)
8(4)
9.1(6)
97.9(0)
7.8(6)
46(6)
2(4)
82.2(6)
54
93
32
94
132
95
003
17(2)
5.0(2)
16.7(2)
88.2(6)
25.7(4)
6(4)
5.5(4)
100(0)
3.3(2)
55(6)
2(4)
72.9(6)
42
76
24
71
92
66
HB1
13(2)
5.9(2)
0(0)
69.7(6)
70.1(0)
5(2)
5.8(4)
95.2(0)
2.0(2)
16(2)
2(4)
49.7(4)
28
ซ,
16
47
182
131
HB2
11(2)
8.5(0)
0(0)'
0(0)
58.1(0)
0(0)
0.9(0)
(0)(6)ซ
0.1(0)
1(0)
0(0)
27.6(2)
10,
17
8
23
57
41
OC4
26(6)
4.4(2)
52.3(6)
86.4(6)
20.2(0)
13(6)
4.3(0)
62.5(2)
RR(6)
RR(6)
RR(6)
RR(6)
52
"
28
"
191
OC1
28(6)
6.0(0)
3.1(0)
30.5(2)
12.4(4)
6(2)
9.5(2)
95.5(0)
5.1(4)
22(4)
0(0)
60.3(6)
30
58
16
57
86
45
OC2
19(4)
5.6(0)
0(0)
60.9(4)
17.9(0)
42)
13(4)
100(1))
8.3(6)
34(13)
1(2)
62.8(6)
SJ4
(55
14
ISO
114
60
16(4)
7.0(0)
0(0)
3.6(0)
22(2)
1(0)
19.7(6)
100(0)
0.7(0)
10(2)
0(0)
30.6(4)
18
35
12
43
118
62
UR "ป' Upstrosm Refaronce; RR - Regional Reference; CC1 also served as reference for Harbor Brook, see page 4-1 1 for further discussion
* No scrapers ' ' .
* No scrapers or Wtorer-colloctors
site on the West Branch Tloughnioga River, only changed
from 21 percent (family-level) to 20 percent (genus/species-
level). Conversely, the farthest downstream station on
Canastota Creek, which exhibited moderate impairment,
decreased from 60 to 27 percent
Metric 6. EPT Index. Because this metric is a restricted form
of taxonomic richness, a similar general response to level of
identification is expected. Small increases in this value are
seen with genus/species-level taxonomy (Tables 5-3,5-4).
Metric?, Shredders/Total No. Individuals. There is minimal
effect on this metric except where families are not designated
as shredders and genera or species are designated.
Metric 8. Hydropsychidae/Total Trichoptera. There is no
effect on this metric since it is based on the number of
individuals in these two taxonomic groups only.
Metric 9. Pinkham-Pearson Community Similarity Index.
The effect of taxonomic level on this metric was minunal
(Figure 5-5). Values ranged from 0.1 to 6.4 for family-level
identifications and from 0.1 to 8.3 for genus/species-level
identification. The middle station on Ctaondaga Creek (OC2)
had a value shift from 4.7 to 8.3, the largest change by far.
Metric 10. Quantitative Similarity Index-Taxa. The effect
of more specific taxonomy was minimal, as indicated by a
high correlation of rank orders (Spearman rank correlation,
50
Evaluation of Method Variation
-------
R=0.93, p=0.002) between the two treatments. The largest
difference in values was observed at Station OC1 with a
family-level value of 42 and a genus/species-level of 22.
Metric 11. Dominants-in-Common-5. A minimal range
of possible values for this metric makes it difficult to
interpret. An example of unpredictable changes in this
metric is illustrated at Stations OC1 and OC3, where the
DIG value fell from 4 to 0 and 2 to 0, respectively, when
the calculation was done at the generic level. At both
stations, there were dominant, family-level taxa in /
common but they were represented by different genera,
thus accounting for the lower DICs. When subjected to
the two treatments, mere was a relatively low correlation
of rank orders (Spearman R=0.35, p=0.44); therefore,
taxonomic treatments could lead to different comparisons
between stations for this metric.
Metric 12. Quantitative Similarity Index-Functional
Feeding Group. There were only minor changes in values
when calculated at family versus genus/species level. Any
differences were probably due to differential availability of
functional feeding group designations among the taxo-
nomic levels. However, rank order correlations showed no
difference with a Spearman rank correlation R of 1.0.
5.2.2 Subsampling Level Effects on Metric
Performance
RBPs provide a mechanism for substantially reducing the
level of effort through randomized subsampling. The
comparisons presented here illustrate the behavior of
identical metrics when calculated on differential
subsampling intensities. Using metric values calculated at
the taxonomic level of genus/species, the effect of
subsample size on metric performance was evaluated. ,
Comparisons of RBPIII with subsampling at die 100-
organism (Table 5-4) and 300-organism (Table 4-3) levels
were done through a combination of correlational
scatterplots and confirmation of differences with Spearman
rank correlations.
A previous unpublished study (Stribling and Gerardi 1993
[draft report]) has shown mat two metrics are strongly
biased by different organism counts, taxa richness and EFT
index, showing a marked increase with higher numbers of
individuals. However, two factors diminish the importance
of these biases. First, the relationship is a predictable one;
second, metrics used in RBP site assessments are evaluated
based on their value relative to reference conditions rather
.than on absolute numbers. Thus, if data representing
reference sites or conditions are collected in the same
manner, these biases become essentially irrelevant. The
following analyses provide further confirmation of these
conclusions, including those concerning minimal effects on,
the other metrics.
Total Bioassessment Score. Overall bidassessment score is
not affected by differential subsample sizes (Figure 5-6);
rank order correlation is perfect (R=1.00).
Metric 1 Taxa Richness. This metric had a value range of
8 to 31 taxa at the 100-organism subsample and 16 to 41 at,
the 300-organism subsample (Figure 5-7). Number of taxa
increases significantly as larger samples are analyzed, but
correlation of rank orders is nearly perfect (Spearman
R=0.95, p=0.000066). Therefore, a larger sample size
would not affect comparisons between stations when using
this metric.
Metric 2. Hilsenhoff Biotic Index. Subsampling level had
no effect on the HBI values with a nearly 1:1 correlation
(Spearman R=0.99, p=0.00) between the two treatments.
Metric 3 Scraper-Filterer Collector Ratio. Although
somewhat more variable, rank orders show significant
correlation for the subsample size (Spearman R=0.93,
p=0.0003) (Figure 5-8). Therefore, subsample size had no
effect on station comparisons using this metric. No
scrapers were selected in the 100-organism subsample at
HB1, which caused the metric to have a value of 0; one
scraper was selected in the 300-organism subsample giving
a value of 16.7.
Metric 4 EPT-Chironomidae Ratio. Subsample size had.
no effect on the results calculated from this metric
(Spearman R=0.92,.p=0.0005).
Metric 5 Percent Contribution of Dominant Taxon.
Subsample size had no effect on the values calculated for
this metric (Spearman R=1.0).
t, . - . ' .
Metric 6 EPT Index. As seen for taxa richness (Metric 1),
a difference was detected for this richness metric, but there
was no difference in rank orders (Spearman R=0.98,
p=0.000002) of the samples. The number of EPT taxa
increases as larger samples are taken, especially at less
degraded sites, due to the sensitivity of the species.
Metric 7 No. Shredders/Total Sample. Similarly to the
Scraper-Filterer Collector Ratio, this functional feeding
group metric appears more variable, but differences in rank
orders are nonsignificant (Spearman R=0.97, p=0.00002)
(Figure 5-9). Different subsample sizes have no effect on
interpretations using this metric. By chance, we got a
higher percentage of shredders in the 100-organism
subsample (19.7 versus 15.8 for the 300-organism
subsample).
Metric 8 Hydropsychidae/Total Trichpptera. This metric is
not significantly affected by different subsample sizes
(Spearman R=0.97, p=0.000014).
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
51
-------
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Evaluation of Method Variation
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Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
55
-------
Evaluation of Method Variation
-------
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Evaluation of Method Variation
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Combined Sewer Overflows and the Multimetric Evaluation ofTheir Biological Effects: Case Studies in Ohio and New York
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Evaluation of Method Variation
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6
Conclusions/Recommendations
6.1 Historical Assessment
Comparisons
Comparisons presented in this document are of three types:
RBP results with different types of historical data:
Hester-Dendy multiplate samplers (Ohio) and the
traveling kick net (New York).
RBP sampling with variation of taxonomic level
(New York).
RBP sampling with variation of subsample size
* (New York).
A comparison of results suggested a reasonably good fit
between Ohio EPA findings and those of the present study.
Subtle discrepancies between the data sets are most likely a
result of the lack of regional calibration for the RBP
analysis technique; that is, there is not a complete under-
standing of which benthic metrics are most appropriate for
the upper Midwest when using kick nets. This might have
weakened the interpretive power of the approach. Also,
there is likely some effect of the different sampling
methodologies (Hester-Dendy multiplate samplers and
square-meter kick nets) on the assessments. It is difficult
to determine if these more subtle differences are due to
differences in methods or changes in biological condition
over time. Bioassessment, as exemplified by the Ohio EPA
ICI (for macroinvertebrates) and ffil (for fish) and the EPA
RBP (for macroinvertebrates), is a valid and technically
sound tool for evaluating impaired waters, particularly
when calibrated on a regional level as is done for the ICI
and IBI. This validation is supported by similar assess-
ments being arrived at by approaches differing hi detail
(this study). .
For the New York portion of the study, all assessments
compared favorably with those most recently performed by
the DEC (Bode et al. 1993). In 1990 sampling, Canastpta
Creek was found to be "moderately impacted" at a single
station downstream of the town. At three stations along its
length, we assessed it as "slightly to moderately impaired"
and "moderately impaired."
A downstream station on Onondaga Creek was assessed as
"severely impacted" in both 1989 and 1990 sampling
efforts (Bode et al. 1993). Our assessments showed this
creek to be "moderately impaired" in upstream reaches and
"severely impaired" near the same station assessed by
DEC. Harbor Brook was assessed similarly between DEC
in 1989 (Bode et all 1993) and here as "moderately" to
"severely impaired." '
Traditional comparisons of biological assessment methods
occur through side-by-side sampling and analysis. These
temporally separate data have provided some useful
insights into the process of bioassessment comparisons. As
mentioned above, differences in results might arise directly
from sampling biases inherent in the sampling gear. This
might be a problem when attempting to directly compare
data from separate bioassessment samples (e.g., the number
of species, the calculated value of an individual metric or
the number of individual organisms collected). The
problem of sampling error (bias) is reduced if comparisons
are made at the level of the overall assessment score rather
than individual metrics.
6.2 Statistical Comparisons
Comparisons were made between RBPII (family-level
identifications) and RBPIII (lowest-practical-level identifi-
cations, usually genus/species), as well as subsample size
(IpO-organism versus 300-organism). As long as the
reference conditions are treated hi the same manner as test
station data (taxonomic and subsampling levels), compari-
sons between assessment results are valid. We found that
although there might have been some differences in
specific metric performance (i,e., metric values) with
different treatments, those values relative to reference
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
61
-------
conditions varied little. Further, there was perfect agree-
ment among total bioassessment scores between the
treatments.
6.2.1 Taxonomlc Level Conclusions
When addressing the question of appropriate taxonomic
level, different concerns do arise. Although similar site
rankings based on condition might be found with different
levels, there can be difficulty hi interpretation of potential
causative factors when using more gross-level identifica-
tions. This is especially true when dealing with metrics
dependent on how individual species adapt to the environ-
ment rather than how they relate to other species. These
metrics include the HBI and those related to functional
feeding groups (scrapers, filterer collectors, shredders).
The tolerance values on which the HBI is based are usually
assigned to species (or genus) level and might not be
available for family. Likewise, functional feeding group
designations become more uncertain as they are assigned to
more general (or higher) taxonomic levels. It is recom-
mended that, in general, taxonomy be performed to the
lowest practical level that will suit the objectives of the
study, wliich will usually be the genus or species level for
biological assessments beyond the screening level. The
decision on taxonomic level might also be refined with
regional calibration of bioassessment techniques.
6.2.2 Subsample Size Conclusions
The argument can be made that a lower number of organ-
isms does not allow a reasonable estimate of biological
diversity. However, as was shown with the taxa richness
metric, as higher numbers of organisms are included in a
sample, the higher the number of detected taxa will be.
This is due to an increase in the probability of rare taxa
being included within a larger subsample. In essence, rare
taxa have little influence on biological assessments using a
multimetric approach because even if rare taxa are col-
lected, their contribution to a multimetric index is minimal.
Conversely, if one's goal is to describe biological diversity
at a site, even an analysis of the total sample (versus a
subsample) is likely inadequate. It is possible to collect
continuously larger samples from a broader diversity of
microhabitats within a site and continue to get additional
taxa. The critical factors are to have consistency in
sampling effort and a properly randomized subsampling --
procedure. As with other sample treatments, subsampling
is appropriate as long as samples from reference sites are
treated in the same way; subsamples less than 100-organ-
isms are not recommended. The recommendation is to base
benthic macroinvertebrate biological assessments on 100-
organism subsample when using RBPs in New York.
6.3 Usefulness of RBPs in '
Assessing CSO Bid ic Effects
Attributing cause and effect to the specific CSO activity is
complicated by other related problems sissociated with
urbanization, e.g., habitat alteration and industrial dis-
charges. However, the bioassessment procedures, with its
integration of total scores, individual metrics (which are
based on known ecology of the benthic community) and
habitat description, provide reasonable technical support
for identifying potential sources of biological impairment.
An impairment due to CSO outfalls was noted in biological
data collected by both Ohio EPA and the present study for a
15- to 20-mile reach of the Scioto River, a 4-mile reach of
the Sandusky River, and a 10-mile reach of the Little
Cuyahoga River. In the cases of the Scioto and Little
Cuyahoga Rivers, upstream stations also located in urban-
ized areas had relatively healthy biological communities
and were effective for comparisons of biological data. The
unimpaired middle station of the Little Cuyahoga River
exhibited recovery of the biota since the correction of
upstream CSOs. The assessments were performed prior to
our gaining information concerning the outfalls.
For the New York study, severe habitat degradation and
alterations were evident at all Onondaga Creek sites and at
the two downstream sites on Harbor Brook. There were
many instances of major habitat differences between
stations on the same stream or between a station and its
regional reference site. However, even with these differ-
ences, impairment due to stressors commonly produced by
CSOs was seen at the middle and lov/er stations on
Canastota Creek and Onondaga Creek,
Results indicated that CSO outfalls had an adverse impact
on the downstream macroinvertebrate assemblages.
Impairment of the benthic biota, in both the Ohio and New
York studies, was manifested by the metrics (1) taxa
richness, (2) scraper/scraper + filterer collector, (3) EPT/
EFT + Chironomidae, (4) percent contribution of dominant
taxon, (5) Hydropsychidae/total Trichoptera, (6) Pinkham-
Pearson Community Similarity Index, (7) QSI-taxa, and (8)
DIC-5.
The bioassessments were instrumental in identifying
impaired reaches of each river at periods that reflected
residual and cumulative effects of CSO outfalls that were
not necessarily actively discharging. Sampling was
performed during normal flow conditions (i.e., not during
the wet or dry season) although several of the Ohio
sampling locations were being affected by increased flow
levels. Results illustrate the utility of biological data for
capturing the effects of intermittent discharge events
without sample collection during stormflows.
62
Combined Sewer Overflows and the Mulume.ric Evaluation of Their Biological Effects: Case Stodie. in Ohio and New York
-------
Hie use of multiple metrics aids in achieving more
accurate assessments than single-parameter assessments.
This was seen in the case of HB1 and HB2, which had
nearly identical metric values for taxa richness but very
different overall biological assessments (HBl-moderate,
HB2-severe). The multimetric approach uses the total
assessment score for comparison to the reference in
determining the biological integrity at a site and uses
individual metrics for interpreting the assessment and
gaining insight as to cause-and-effect relationships. The
associated habitat assessment enabled a characterization of
the physical habitat alteration, strengthening the ability to
identify additional potential sources of impairment. For
example, the nonimpaired biological condition assessment
in the presence of degraded habitat on the Sandusky River
(SA2) is a likely indication of some form of nutrient
enrichment since, as discussed earlier (Section 3.2.3.4),
the initial phases of nutrient enrichment cause an increase
in the biota. If the nutrient enrichment is mild to moder-
ate, the biological community balances between the effects
of enhanced biota and the next phase of enrichment,
oxygen depletion. In such instances, the biology would
continue to score higher than the surrounding habitat
would be expected to support.
6.4 The Place of Bioassessment In
Watershed Protection
Another potential application for bioassessments is within
the total maximum daily load (TMDL) process, which is
one of the essential tools of the watershed protection
approach. The watershed protection approach attempts to
evaluate watersheds on a holistic, rather man piecemeal,
basis. A TMDL is defined by USEPA guidance and
regulations as being equivalent to the loading capacity of a
waterbody and the sum of the individual wasteload
allocations (WLAs) for point sources, load allocations
(LAs) for nonpoint sources, and natural background
sources, and a margin of safety to account for uncertainties
about the relationship among stressors, controls, and the
quality of the receiving water (USEPA 1994b).
TMDLs are required when states determine that technol-
ogy-based controls will not result in a waterbody's meeting
water quality standards, including its designated uses. The
TMDL process can provide sufficient and necessary
information for making decisions on the implementation of
appropriate pollution reduction tools such as best manage-
ment practices (BMPs), ecological restoration, or engi-
neered active or passive treatment technologies (USEPA
1994c).
Although TMDLs until now have been primarily chemi-
cal-specific, biological assessment shows promise as a tool
for going beyond chemical water, quality to biological
endpoints and the aquatic life uses of the waterbody.
Biological assessments provide a direct evaluation of
ecosystem condition by integrating physical habitat quality
with biological condition. The evaluation is accomplished
by comparison to empirically-defined, regionalized
expectations of biological conditions (reference condi-
tions). As was demonstrated in these case studies,
bioassessments can often detect the biological impact of
CSOs and other intermittent discharges in urbanized
watersheds affected by multiple stressors. Because CSOs
. contribute to the pollution load entering a waterbody, they
must be considered in TMDL development. Biological
assessment used in the TMDL process can help: .
identify waters that are ecologically unpaired and
might be in nonattainment of chemical water
quality standards; this would help in the siting
and installation of appropriate controls.
Prioritize and target ecologically impaired waters.
Aid in the development and implementation of
TMDLs for nonchemical stressors within a
watershed.
Assess the effectiveness of installed pollution
control tools in protecting aquatic resources.
Where the metrics for a region have, been suffi-
ciently refined, the diagnostic capabilities of some
metrics might allow,some conclusions to be
drawn with regard to specific causes of biological
impairment in a waterbody.
Other current USEPA programs that can benefit from the use
of biological assessments include 1994 CSO Control Policy.
(section 1.1) , stormwater and wet-weather monitoring,
305(b) reporting, and biological criteria. Many states have
incorporated biological assessments into then- 305(b) reports,
and many are currently developing biological criteria for
waterbodies in their ecoregions. As illustrated in this report,
biological assessments are useful for determining impair-
ments from episodic events such as those accompanied by wet
weather and stormwater without the necessity of sampling
during the actual event
Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
63
-------
-------
7
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Combined Sewer Overflows and the Multimetric Evaluation of Their Biological Effects: Case Studies in Ohio and New York
67
-------
-------
Appendix A
Taxonomic List of
Bentfiic Macroifiverfebrates
Collected in Ohio, September f 992
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Appendix B
Taxon bmfc List of
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Coffecfecf in New York, September 1993
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Appendix C
Quality Control Elements
-------
-------
Activity
Routine, Method, or SOP and Responsibility
habitat assessment
as per Barbour and Stribling 1991; parameters and rating procedure described in
section 2.1, this document; observations performed prior to benthic sampling in order
to avoid bias; original field data sheets archived in Tetra Tech, Owings Mills, MD,
office; responsibility - Dr. J.B. Stribling, Tetra Tech, Inc., 10045 Red Run Blvd., Suite
110, Owings Mills. MD 21117
benthic sampling
as per Plafkin et al. 1989; also described in section 2.2, this document; double-
composite 1m2 kicknet samples, mesh size, standard no. 30 mesh (openings 600^),
larger substrate particles (cobble and small boulder) scrubbed by hand to dislodge
attached organisms; 1 from fast water riffle composited with 1 from slow water riffle in
sieve-bottomed bucket (openings 600^): organisms adhering to or entwined in net
removed with forceps and placed into sieve bucket; responsibility (for Ohio case
study) - Dr. J.B. Stribling, S. W. LJpham, Tetra Tech, Dr. G.A. Burton, Ms.
(Catherine Jacher, Biological Sciences Department, Wright State University, Dayton,
OH 45435, Mr. Chris Faulkner, U.S. EPA/AWPD/Monitoring Branch (WH-553), 401
M Street, Washington, DC 20460; (for New York case study) - Dr. J.B. Stribling,
Ms. C. Gerardi, Tetra Tech, Ms. Marjorie C. Coombs, U.S. EPA, Office of Science
and Technology, Standards and Applied Sciences Division, 401 M Street, SW #4305,
Washington, DC 20460
subsampling
described in section 2-2, this document; emptied from sieve bucket into gridded
sorting tray (with numbered grids), manipulated into even spread within tray; if too
much detrital or algal content, sample split into two trays (when split between two
trays, identical grids are picked simultaneously between the two); using random
numbers table, individual grids selected for picking, all organisms removed with fine
forceps and placed directly into prelabelted sample container with approximately 70%
ethanol; counted organisms placed in container successive grids selected until AT
LEAST 300 organisms were obtained (Ohio), 200 or 100 organisms (New York); if
subsampte total was reached prior to completing a grid, the remaining organisms
were removed form that grid; for mobile organisms, visual estimates were made of the
number of individuals moving into and out of the grid being picked and an
approximation of that estimate was taken (Ohio), new subsampling screen greatly
reduced mobility of organisms for the New York study; responsibility - Dr. J.B.
Stribling
taxonomy
taxonomic literature used in performing identifications is presented in section 2.2, this
document; responsibility - Dr. M.C. Swift and B. Kulinska, Monticello Ecological
Research Station, University of Minnesota, P.O. Box 500, Monticello, MN 55362;
cladocerans were identified by Dr. Stanley Dodson, Department of Zoology, Birge
Hall, University of Wisconsin, Madison, Wl 53706 (Ohio study Only)
voucher specimens
(samples)
in storage, responsibility - Dr. J.B. Stribling
abundance totals in
metric calculations
special considerations in the use of abundance totals for calculation of the metrics is
presented in section 2.2 of this document; responsibility - Dr. J.B. Stribling, Ms. C.
Gerardi, Tetra Tech .
metric calculations
metric calculations were performed by hand according to the individual metric
descriptions presented in section 2.3 of this document; approximately 21 % of the
metrics were recalculated by hand as a QC check; another approximately 10% were
recalculated by computer as further check; responsibility - Ms. C. Gerardi, Dr. J.B.
Stribling . ' ^
report preparation
authorship, organization, graphics production; responsibility- Dr. J.B. Stribling, Dr.
Michael T. Barbour' Tetra Tech
-------
Problems (Ohio Study)
high water, unable to sample Cuyahoga
River stations
ecoregiona! reference station for Littte
Cuyahoga River flooded, 9/24/92, unable to
sample Breakneck Creek at Kent
high water at Ohio EPA-recommended
sampling station prevented sampling (Little
Cuyahoga River at Mogadore)
depressed abundance of organisms in
kieknet samples at Littte Cuyahoga stations
CR2andCR3
needed rapid turnaround time on taxonomic
analysis of samples
Problems (New York Study)
deep water, muck bottom - unable to sample
beyond RBPI screening assessment at HB3
hyperabundance of amphipods at regional
reference site (CHR4) for Harbor Brook &
Canastota Creek
conductivity meter began to give erratic
Action(s) taken .
aborted sampling activity on 9/10/92 following completion of
Scioto (9/8/92) and Sandusky (9/9/92) sampling; opted to return
in 2 weeks, tentatively set return for 9/24/92; on returning
9/24/92 and Cuyahoga still 3 feet above normal arid unable to
sample, via pay telephone to Ohio EPA (J. DeShon) located
workable stations on the Little Cuyahoga River
decided to rejy on site-specific upstream reference (station CR1
at Mogadore) ;
sampled approximately O.t mite farther upstream
total samples picked, but still falling below 300-crganism goal
primarily generic-level identifications performed
Action(s) taken
ended assessment at RBPI level, site (HB3) not used in
biological assessment .
upstream site on Canastota Creek (CC1) used for reference
comparison
stopped taking conductivity readings
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