EPA#823-R1-0002
Applicability of Great Lakes NEEAR Dataset to Inland
Recreational Water Criteria: Summary of Key Studies
U.S. Environmental Protection Agency
November 2010
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Inland Waters Summary Report November 2010
Contents
Contents iii
Tables iv
Figures iv
Abbreviations and Acronyms v
Executive Summary 1
1. Introduction 3
1.1. Objective 3
1.2. Methodology 4
1.2.1. Documents reviewed 4
1.2.2. Topics featured in document review 5
1.3. General descriptions of inland flowing, inland impounded, and Great Lakes coastal
settings 7
1.3.1. Qualitative comparison of indicator processes in inland and coastal waters 7
1.3.2. Brief review of epidemiology studies conducted for inland waters 9
2. Documents review 12
2.1. Summary of findings 12
2.2. Detailed reviews 19
2.2.1. Final Report on the Experts Scientific Workshop on Critical Research and Science
Needs for the Development of Recreational Water Quality Criteria for Inland
Waters (WERF 2009) 19
2.2.2. Meeting Report: Knowledge and Gaps in Developing Microbial Criteria for Inland
Recreational Waters (Dorevitch et al. 2010) 27
2.2.3. Literature Review of Assessment of the Applicability of Existing Epidemiology
Data to Inland Waters (USEPA 20 lOa) 31
2.2.4. Sampling and Consideration of Variability (Temporal and Spatial) for Monitoring
of Recreational Waters (USEP A 201 Ob) 34
2.2.5. Quantification of Pathogens and Sources of Microbial Indicators for QMRA in
Recreational Waters (WERF 2010a) 36
2.3. Methodology Performance and Relevance to Applicability of Criteria to Inland Waters
(compilation of findings from multiple reports) 38
References 43
in
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Inland Waters Summary Report November 2010
Tables
Table 1. Key areas that the reviewed reports and publications used to compare and contrast
Great Lakes and inland waters 6
Table 2. Study purpose, methodology, findings and limitations for the Final Report on the
Experts Scientific Workshop on Critical Research and Science Needs for the
Development of Recreational Water Quality Criteria for Inland Waters (WERF
2009) 12
Table 3. Study purpose, methodology, findings and limitations for Meeting Report:
Knowledge Gaps in Developing Microbial Criteria for Inland Recreational
Waters (Dorevitch et al. 2010) 14
Table 4. Study purpose, methodology, findings and limitations for Literature Review of
Assessment of the Applicability of Existing Epidemiology Data to Inland Waters
(USEPA2010a) 15
Table 5. Study purpose, methodology, major findings and limitations for Sampling and
Consideration of Variability (Temporal and Spatial) for Monitoring of
Recreational Waters (USEPA 2010b) 16
Table 6. Purpose, methodology, major findings, and limitations of draft final report.
Quantification of Pathogens and Sources of Microbial Indicators for QMRA in
Recreational Waters (WERF 2010a) 17
Table 7. Purpose, methodology, major findings, and limitations of Methodology
Performance and Relevance to Applicability of Criteria to Inland Waters
(compilation of findings from multiple reports) 18
Table 8. Priority research activities from the 2009 Inland Waters Workshop (WERF 2009) 24
Table 9. Comprehensive list of proposed research activities from the 2009 Inland Waters
Workshop (WERF 2009) 24
Figures
Figure 1. Illustration of fecal indicator organism sources for coastal waters 8
Figure 2. Illustration of fecal indicator organism sources for inland waters 8
Figure 3. Paired qPCR and Culture Enterococcus Data: Huntington Beach: 8 AM Samples
Only 40
Figure 4. Paired qPCR and Culture Enterococcus Data: Huntington Beach: 3 PM Samples
Only 40
IV
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Inland Waters Summary Report
November 2010
AWQC
BMP
BEACH Act
CPU
CPSP
CSO
CWA
DNA
EPA
EC
FIB
GI
MF
MPN
MST
NEEAR
NPDES
PC
PCR
POTW
QMRA
qPCR
RCT
TMDL
UV
VBNC
WERF
WHO
WWTP
Abbreviations and Acronyms
ambient water quality criteria
best management practice
Beaches Environmental Assessment and Coastal Health Act
colony forming unit
Critical Path Science Plan
combined sewer overflow
Clean Water Act
deoxyribonucleic acid
U.S. Environmental Protection Agency
European Commission
fecal indicator bacteria
gastrointestinal
membrane filtration
most probable number
microbial source tracking
National Epidemiological and Environmental Assessment of Recreational
Water Study
National Pollutant Discharge Elimination System
prospective cohort
polymerase chain reaction
publicly-owned treatment works
quantitative microbial risk assessment
quantitative polymerase chain reaction
randomized control trial
total maximum daily load(s)
ultraviolet (light)
viable but not culturable
Water Environment Research Foundation
World Health Organization
wastewater treatment plant
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Inland Waters Summary Report November 2010
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VI
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Executive Summary
This report evaluates the applicability of NEEAR Great Lakes data to inland waters and assesses
the similarities and differences between coastal freshwaters and inland freshwaters to establish if
there are significant differences to justify additional studies to support applicability of criteria to
inland waters. Thirteen reports and peer-reviewed key publications pertaining to the
establishment of new or revised recreational water quality criteria appropriate to U.S. inland
waters were reviewed in this Inland Waters Summary Report. Focused observations and
conclusions were extracted and organized into several finding categories in the table below. The
reports and articles provide (1) overall assessments on whether criteria developed on the basis of
studies of coastal waters (marine/estuarine and Great Lakes waters) are applicable to inland
waters; (2) findings concerning differences in the microbial ecology, fate, and transport of
indicators in inland and coastal waters; and (3) discussions of likely differences in implementing
new or revised criteria to inland and coastal waters, including indicator detection and monitoring
schemes. Current ongoing and future research EPA is pursuing and planning is also addressed in
individual report sections, along with the suggestions provided by each report's authors. Major
findings as reported in the reports for each of the categories are summarized below (not in order
of importance). Note that the table presents the major findings as proposed by the study authors.
The findings differ in the degree to which they are supported either through data or citations of
other studies. In some cases, the findings might reflect a conclusion drawn by the study authors
based on best scientific judgment when data was insufficient to offer a complete scientific
assessment.
Finding category
Overall assessments
pertaining to the
extension of coastal
water criteria to inland
waters
Conclusions and observations
Fecal pollution source is the main driver of health risk at inland and coastal
sites, before specific setting (e.g. physical and biological processes). This
observation is consistent with findings from quantitative microbial risk
assessment (QMRA) studies and the limited number of epidemiology studies
conducted in both inland and coastal settings and for sites with different fecal
pollution sources.
Application of coastal water-based criteria to inland recreational waters is
expected to result in sporadic, mild illness at rates no higher and probably
lower than those experienced in Great Lakes/coastal waters.
Inland and Great Lakes/coastal waters might pose very different risks of
severe diseases.
Data and health effects relationships developed for Great Lakes waters that
are primarily affected by publicly-owned treatment works (POTW) effluent are
generally believed to be applicable to inland waters primarily affected by
POTW effluent.
Different studies interpret the state of the science differently from each other.
All the studies directly assessing the extension of criteria on the basis of
epidemiology studies of POTW-impacted Great Lakes waters to inland waters
note that there are no definitive epidemiology studies to support or preclude
making the extension.
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Finding category
Conclusions and observations
Experts participating in the 2009 Water Environment Research Foundation
(WERF) inland waters workshop speculate that livestock and wildlife fecal
pollution sources affect a greater proportion of inland waters than coastal
waters. However, inland waters comprise a diverse set and individual sites
might be affected by POTW, diffuse human pollution, livestock fecal pollution,
or fecal pollution from wildlife.
Differences in
occurrences, fate, and
transport of indicators
in inland and coastal
waters
Fecal pollution sources discharge directly to inland waters, and fecal pollution
undergoes less dilution in inland waters than in Great Lakes/coastal waters.
Understanding that runoff and streamflow are highly variable, the result of less
dilution capacity in inland waters results in higher densities of pathogens in
inland waters under some flow conditions and higher risk of disease from
exposure to inland waters.
Reported ranges of indicator densities in inland and Great Lakes/coastal
waters are comparable. While relatively few data are available for systematic
comparison of response of coastal and inland sites to rain events, it is likely
that indicator variability within storm events is greater for inland waters than for
coastal waters.
Indicator decay rates in Great Lakes and inland waters fall within comparable
ranges.
Escherichia co/; growth has been observed in water columns and sediments of
both inland and coastal waters. Enterococcus growth has also been observed
in soils and sediments, though fewer studies have assessed Enterococcus
potential, and differences in growth in inland and coastal settings cannot be
assessed. Growth might be more likely in sediments and soils of inland waters
than in those of coastal waters.
Resuspension mechanics of sediment and soil-associated indicators and
pathogens differ for coastal and inland waters. Resuspension might be more
important in inland waters because turbulent shear at the sediment-water
interface results in large loads of suspended organisms and particles and
because dilution is lower than that of resuspended indicator organisms at
coastal sites.
Quantitative polymerase chain reaction (qPCR) and cultural enumerations of
indicator organisms tend to be better correlated for fresh fecal material and
very poorly correlated foraged fecal pollution, indicators that have been
subjected to sunlight, and chlorinated waters.
Findings related to
implementation of
criteria
Inland waters are more widely dispersed geographically and cover more
territory overall (as stream miles) than do coastal waters (as coastal miles).
Inland waters typically have use patterns different from developed coastal
beaches. Monitoring for such inland waters likely entails assessing water
quality on the basis of fewer samples.
For inland waters, the ratio of qPCR counts of indicators to culture counts of
indicators likely differs from that typical of coastal sites because of differences
in age of fecal pollution, presence and concentration of chlorinated secondary
effluent, and exposure of fecal pollution to solar radiation.
Standardized sanitary survey tools should be developed for both inland and
coastal waters. Completion of sanitary surveys should be an integral
component in development of monitoring schemes.
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Inland Waters Summary Report November 2010
1. Introduction
1.1. Objective
New or revised ambient water quality criteria (AWQC) for the protection of primary contact
recreation are likely to be based on health effects observed in epidemiology studies of coastal
waters. A decision to extend or not extend those criteria to inland waters must be supported by
analysis of the science of inland and coastal waters as well as analysis of practical concerns, such
as likely differences in use and sampling of inland and coastal waters. Recognizing those needs,
the U.S. Environmental Protection Agency's (EPA's) Critical Path Science Plan for the
Development of New or Revised Criteria for Recreational Waters (the CPSP; USEPA 2007)
proposed studies to develop the information necessary to inform extrapolation of AWQC.
This report summarizes the knowledge that EPA collected and produced in response to the CPSP
based on a review of thirteen reports and key research articles. Each report and article is
summarized, and the key concepts, results, or conclusions are highlighted. Three reports and five
publications were pooled to condense all aspects of monitoring methodology relevant to this
report's subject matter. Findings from these reports will be used to develop analyses that will
support a decision of whether and how AWQC can be extended to inland waters on the basis of
epidemiology studies conducted as part of EPA's National Epidemiological and Environmental
Assessment of Recreational (NEEAR) Water Study, which include the Great Lakes
epidemiology studies.
Stakeholder and scientific community concerns
In stakeholder meetings and in the scientific literature, concerns have been expressed regarding
both the scientific and practical considerations of extending AWQC developed for coastal waters
to inland waters. Concerns about the science of extending AWQC generally relate to perceptions
or findings that indicator organisms perform differently in inland waters than in coastal waters.
In this report, performance is taken as (1) the relationship between indicator density and the
observed rates of illness in a particular type of water and (2) the fate and transport of indicators
relative to pathogens and loads from specific fecal pollution sources. Practical concerns relate to
the development of monitoring schemes and interpretation of sample results for inland waters.
Paramount among those concerns is the interpretation for all waters of indicator densities from
samples collected during and immediately after precipitation (especially rain) events (NRC
2004).
To develop context for this report, PowerPoint presentations from stakeholder meetings and
correspondence between EPA and stakeholders were reviewed. Questions drawn from those
communications are presented below. The questions provide a focus for reviewing the
documents presented in this study. Some of these questions do not relate to differences between
inland and coastal waters per se.
Questions related to the science of indicators
How does the persistence of fecal indicator organisms in typical inland soils and
sediments differ from that in coastal soils and sediments?
How does the fecal pollution source affect the performance of indicators in inland and
coastal waters? What are alternative criteria appropriate for fecal pollution sources other
than publicly owned treatment works (POTW) effluent?
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Inland Waters Summary Report November 2010
Does indicator performance differ in flowing waters, impounded inland and coastal
waters?
Does climate (i.e., tropical, temperate, and subtropical) affect indicator performance?
If E. coli is a better indicator of fecal pollution in freshwaters, could Enterococcus criteria
be equally protective of human health for inland and coastal waters?
Questions related to implementing indicator-based criteria to inland waters
How do indicator-based AWQC for beaches, where monitoring occurs frequently, apply
to inland waters, where recreational use is likely intermittent and where water quality
assessments are based on much less frequent sampling?
What criterion relates to long-term water quality and eliminates undue influence of spikes
in fecal pollution and indicator density?
Can/should criteria be relaxed during extreme-flow events?
How will culture methods be integrated with new or revised criteria? Is a rapid method
needed for inland waters, particularly those with low use?
1.2. Methodology
1.2.1. Documents reviewed
Eight studies were originally proposed for review for this report. Of those, seven were available
for review during preparation of the report, and one further study was added. The added study
(number 2 below) is a condensed version of the Water Environmental Research Foundation
(WERF) experts workshop report (number 1 below). The condensed version of the workshop
proceedings was reviewed separately because it has been distributed widely in the scientific
community (it is a peer-reviewed publication) and because it makes more definitive statements
than the full workshop report. Key documents reviewed for this report were as follows:
1. Final Report on the Experts Scientific Workshop on Critical Research and Science Needs
for the Development of Recreational Water Quality Criteria for Inland Waters (WERF
2009)
2. Meeting Report: Knowledge Gaps in Developing Microbial Criteria for Inland
Recreational Waters (Dorevitch et al. 2010)
3. Final report Literature Review of Assessment of the Applicability of Existing
Epidemiology Data to Inland Waters (USEPA 2010a)
4. Final report Sampling and Consideration of Variability (Temporal and Spatial) for
Monitoring of Recreational Waters (USEPA 201 Ob)
5. Interim draft report Comparison of Different Methodologies for the Enumeration of Fecal
Indicator Organisms (USEPA 2010c)
6. Draft final report Quantification of Pathogens and Sources of Microbial Indicators for
QMRA in Recreational Waters (WERF 2010a)
7. Final report Comparative Evaluation of Molecular and Culture Methods for Fecal
Indicator Bacteria for use in Inland Recreational Waters (WERF 201 Ob)
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Inland Waters Summary Report November 2010
8. Results of the Single-Laboratory Validation of EPA Method A for Enterococci and
Method B for Bacteroidales in Waters by TaqManฎ Quantitative Polymerase Chain
Reaction (qPCR) Assay (USEPA 2010d)
In addition, the following five key articles were selected and reviewed for their direct relevance
to the subject matter:
9. "Covariation and Photoinactivation of Traditional and Novel Indicator Organisms and
Human Viruses at a Sewage-Impacted Marine Beach" (Boehm et al. 2009)
10. "Persistence of Nucleic Acid Markers of Health-Relevant Organisms in Seawater
Microcosms" (Walters et al. 2009)
11. "Discrimination of Viable and Dead Fecal Bacteroidales Bacteria by Quantitative PCR
with Propidium Monoazide" (Bae and Wuertz 2009)
12. "Linking Non-Culturable (qPCR) and Culturable Enterococci Densities with
Hydrometeorological Conditions" (Byappanahalli et al. 2010)
13. "A Cross Comparison of QPCR to Agar-Based or Defined Substrate Methods for
Determination of Escherichia coli and Enterococci in Municipal Water Quality
Monitoring Programs" (Lavender and Kinzelman 2009)
Note that five out of eight reports (#1 to 4 and 6) are discussed individually in this report, while
the other reports (#5, 7, and 8), as well as the five published research articles (#9 to 13), are
discussed together in Section 2.3 to condense all aspects of methodology performance with
respect to applicability of criteria to inland waters.
1.2.2. Topics featured in document review
The stakeholder questions presented in Section 1.1.2 and the physical differences between inland
and coastal waters presented in Section 1.3 provide topic areas that were emphasized for review
and synthesis from the key reports and articles. Those areas can be divided into topics that
inform the performance of indicators and topics related to differences in implementing criteria in
inland and coastal waters.
Topics related to the performance of indicators in inland and coastal waters include findings on
the intrinsic physical, biological, and hydrologic differences between inland and coastal waters;
findings related to the incidence of pathogens or the association of illness in inland and coastal
waters; and findings on differences in method performance for inland and coastal waters.
Topics related to implementing criteria relate to differences in the content of sanitary surveys for
inland and coastal waters, practical constraints causing inland water monitoring plans to differ
from those for coastal waters, and differences in how water quality sample results are interpreted.
Section 1.3 describes the features of inland and coastal waters with the potential to result in
differences in the association of indicator levels with health effects. A thorough exploration of
the differences in criteria for inland and coastal waters entails review of epidemiology,
hydrodynamics, fecal pollution sources, use patterns, and performance of indicator measurement
techniques. The reports and research articles reviewed herein were selected according to their
coverage of all those subject areas. The specific factors pertinent to extending coastal water
criteria to inland waters reviewed in each study are presented in Table 1.
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Inland Waters Summary Report
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Table 1. Key areas that the reviewed reports and publications used to compare and contrast Great
Lakes and inland waters
Report/publication
Final Report on the Experts Scientific
Workshop on Critical Research and
Science Needs for the Development of
Recreational Water Quality Criteria for
Inland Waters (WERF 2009)
Meeting Report: Knowledge Gaps in
Developing Microbial Criteria for Inland
Recreational Waters (Dorevitch et al. 2010)
Literature Review of Assessment of the
Applicability of Existing Epidemiology Data
to Inland Waters (USEPA 201 Oa)
Sampling and Consideration of Variability
(Temporal and Spatial) for Monitoring of
Recreational Waters (USEPA 201 Ob)
Comparison of Different Methodologies for
the enumeration of Fecal Indicator
Organisms (USEPA 201 Oc)
Quantification of Pathogens and Sources
of Microbial Indicators for QMRA in
Recreational Waters (WERF 2010a)
Comparative Evaluation of Molecular and
Culture Methods for Fecal Indicator
Bacteria for use in Inland Recreational
Waters (WERF 201 Ob)
Single Lab Validation Study of
Enterococcus qPCR and Bacteroidales
qPCR (USEPA 201 Od)
"Covariation and Photoinactivation of
Traditional and Novel Indicator Organisms
and Human Viruses at a Sewage-Impacted
Marine Beach" (Boehm et al. 2009)
"Persistence of Nucleic Acid Markers of
Health-Relevant Organisms in Seawater
Microcosms" (Walters et al. 2009)
"Discrimination of Viable and Dead Fecal
Bacteroidales Bacteria by Quantitative
PCR with Propidium Monoazide" (Bae and
Wuertz 2009)
"Linking Non-Culturable (qPCR) and
Culturable Enterococci Densities with
Hydrometeorological Conditions"
(Byappanahalli et al. 2010)
Inland vs. coastal water factors addressed
Epidemiology studies of inland and coastal sites;
differences related to hydrology and resuspension; fecal
source differences; differences related to performance of
detection techniques; monitoring strategies for inland and
coastal sites; data gaps and research prioritization
Epidemiology studies of inland and coastal sites;
differences related to hydrology and resuspension; fecal
source differences; data gaps and research prioritization
Epidemiology and watershed-scale studies of inland and
coastal sites; differences related to hydrology and
resuspension; fate and transport characteristics of
indicators in coastal and inland settings
The hydrology of inland and coastal sites; variability in
indicator density at inland and coastal sites; sampling
schemes and their association with inland and coastal sites
Differences in performance of enumeration techniques;
identification of site features impacting comparison of qPCR
and culture counts of fecal indicator organisms
Performance of enumeration techniques for different water
matrices, indicators and settings; use of water quality data
in a quantitative microbial risk assessment (QMRA)
framework for assessing health risks (in the absence of
epidemiology studies)
Performance of qPCR enumeration of fecal indicators for
waters from different settings and for different laboratories;
evaluation of the uncertainty of qPCR in enumeration of
fecal indicator bacteria
Method performance of qPCR in a variety of fresh and
marine water settings
Impact of photoinactivation on method performance for
fecal indicator bacteria (FIB) monitoring
Impact of seawater quality and environmental factors on
FIB DNA persistence in marine settings
Comparison of method performance and significance of FIB
viability forqPCR and culture-based assays in marine
settings
Impact of hydrometeorological factors on method
performance for FIB monitoring
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Report/publication
Inland vs. coastal water factors addressed
"A Cross Comparison of QPCR to Agar-
Based or Defined Substrate Methods for
Determination of Escherichia coli and
Enterococci in Municipal Water Quality
Monitoring Programs" (Lavender and
Kinzelman 2009)
Comparison of method performance forqPCR and culture-
based assays in surface waters, municipal stormwater and
wastewater
1.3. General descriptions of inland flowing, inland impounded, and Great Lakes
coastal settings
Inland waters are waterbodies that are not coastal recreational waters as defined by the Clean
Water Act (CWA). They are typically freshwater but can include some saltwater (estuarine)
waterbodies (e.g., streams with tidal influences). They include flowing (rivers and streams) and
impounded (lakes and reservoirs) waterbodies, but not the Great Lakes, which are defined as
coastal waters under the Beaches Environmental Assessment and Coastal Health (BEACH) Act
of 2000.
This section provides qualitative comparisons of coastal and inland waters. It is intended as
background material and is included to help readers understand and interpret findings of the
studies reviewed. Two types of comparisons are provided. In Section 1.3.1, the physical,
hydrological, and biological differences in coastal and inland sites are described. Such
differences influence indicator fate and transport and the association of indicators with specific
fecal pollution sources. In Section 1.3.2, the findings of epidemiology studies of inland waters
are reviewed. Epidemiology studies provide the best indication of the risks associated with
recreation in inland and coastal waters and association of inland sites with specific fecal
pollution sources and pathogens.
1.3.1. Qualitative comparison of indicator processes in inland and coastal waters
With the understanding that inland and coastal waters are diverse, generalizations about these
waters are provided in this section as an introduction to the findings of the studies reviewed for
this report. Intrinsic physical differences between inland and coastal settings include the
following:
the ways in which the sites are loaded with fecal pollution;
the mechanisms by which indicators are advected into and out of sites;
hydrograph and indicator organism density responses to rain events;
the locations and mechanisms important in resuspension of sediment indicators;
the dilution of fecal pollution loads; and
average insolation (average incident solar radiation per water surface area).
Those differences are illustrated in Figure 1 and Figure 2 and are described below. Other
important differences between recreational sites include the predominant fecal pollution
source(s) and the frequency of use for recreation. Those differences are not intrinsic to inland
and coastal waters, and no data sources providing means for quantitative assessment of their
importance were reviewed for this report.
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All sources exhibittemporal
and spatial variability
Pointsource
Direct deposition
Diffuse sources
sediments via wave action
Figure 1. Illustration of fecal indicator organism sources for coastal waters
Shading
Direct
deposition
Pointsource
Growth in sediments and
banks; transport during rain
events
Figure 2. Illustration of fecal indicator organism sources for inland waters
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Inland Waters Summary Report November 2010
Inland and coastal waters receive fecal indicator bacteria (FIB) from point sources, diffuse
sources including nonpoint sources, direct deposition (e.g., gulls or cattle in a stream), and
resuspension of FIB in sediments or overbanks. It is likely that the overall predominant sources
in inland waters differ from those in coastal waters. However, for a specific stream compared to
a specific coastal water, the sources might be the same or very similar. Human fecal pollution
and nonhuman fecal pollution are associated with different types of pathogens. Those pathogens,
in turn, pose different hazards, and the exposure necessary to observe a given response (e.g.,
adverse health effect) in the exposed population also differs.
FIB loading and hydrodynamics in POTW-impacted inland and coastal waters are generally
similar. POTW discharges to both inland and coastal sites are relatively steady and have FIB
densities that are variable but not dependent on whether a site is coastal or inland. Loading from
non-POTW sources might differ significantly for inland and coastal sites. Non-POTW fecal
pollution is loaded to receiving waters primarily during and immediately following rain events.
Because non-POTW sources are usually in closer proximity to inland waters than to coastal
waters and because the volumes of inland waters receiving fecal pollution are lower than those of
coastal waters, fecal pollution in inland waters is expected to be generally less dilute than that in
coastal waters. Because dose-response functions for individual pathogens are not linear,
differences in dilution in coastal and inland waters might result in differences in incidence of
illness typical of the two sites. Differences in incidence of illness are particularly important for
pathogens such as E. coli O157:H7, which can result in very serious illness.
Inland and coastal waters differ in typical soils and sediments, the ratio of the sediment area to
the water volume, and the mechanisms most responsible for resuspension of sediment-associated
indicator organisms. Together, those factors can cause differences in the abundance of
resuspended indicator organisms in the two settings. Because resuspended indicator organisms
are not associated with a specific fecal pollution source, they are not good indicators of fecal
pollution sources and might confound interpretation of microbial water quality from indicator
density measurements. None of the studies reviewed for this report sought to associate inland or
coastal waters with specific soil and sediment types or to compare and contrast the extent to
which growth is likely in either setting, although one report (WERF 2009) asserts that growth is
more likely in the soils and sediments of inland waters and at the water-sediment interface. In
inland waters, resuspension is by means of turbulent shear at the stream bottom, while in coastal
waters, resuspension is primarily due to wave action. The net resuspended indicator load at a
given site is a function of both the abundance of sediment-associated indicators and the processes
by which free or particle-associated organisms are drawn from the sediments. Although a
quantitative comparison of resuspension in inland and coastal waters is not possible, it is likely
that resuspension is different in inland and coastal waters because of the different sediments
typical of the sites and the very different mechanisms that cause resuspension in the two settings.
No information in the documents reviewed indicates whether the differences would affect the
relationship between indicator density and adverse health outcomes in exposed persons.
1.3.2. Brief review of epidemiology studies conducted for inland waters
At present, epidemiology studies provide the best means for comparing recreation-associated
risks in inland and coastal sites. However, due to the complex and variable processes associated
with the transport of fecal pollution and indicators to recreational sites, only a few studies have
demonstrated a correlation between indicators and health risks via modeling. Recently published
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Inland Waters Summary Report November 2010
QMRA studies indicate the potential for connecting indicator densities and health effects via
modeling (Schoen and Ashbolt 2010; Seller et el. 2010a, 2010b).
As context for the studies reviewed in this document, a brief review of epidemiology studies
conducted at inland sites is presented below. These studies were conducted for different purposes
and with different methodologies, and these differences hamper direct comparison of their
results. In general, the studies have resulted in two types of data. First, they produce a measure of
the increase in odds (or likelihood) of some health endpoint (usually gastrointestinal [GI] illness)
for swimmers as compared to non-swimmers. Such an odds ratio does not relate to the water
quality or indicator level. Second, some of the studies produce an association of the incidence of
health endpoints with the level (density) of indicators to which swimmers were exposed. In some
cases, no statistically significant association is observed. That lack of association could relate to
a lack of association between the indicator and a specific fecal pollution source or could relate to
the epidemiology study design. In a limited number of cases, studies have produced health
effects curves predicting the incidence of illness as a function of indicator density.
To date, eight sets of U.S. and international epidemiological studies have been conducted to
evaluate the association of swimming in inland surface waters with the incidence of GI illness
(Stevenson 1953; Dufour 1984; Seyfried et al. 1985a, 1985b; Ferley et al. 1989; Calderon 1991;
Wiedenmann et al. 2006; European Commission [EC] 2009a, 2009b [referred to as Epibathe
studies]; Marion et al. 2010). They are grouped below as follows:
investigation of (presumably) POTW-impacted inland sites (Dufour 1984; Weidenmann
et al. 2006; EC 2009a, 2009b; Marion et al. 2010);
investigation of untreated domestic sewage affected inland flowing waters (Ferley et al.
1989)
investigation of unspecified inland waters1 with unspecified fecal sources (Seyfried et al.,
1985a, 1985b)
investigation of flowing and impounded inland waters (Dufour 1984; Stevenson et al.
1953; Weidenmann et al. 2006; EC 2009a, 2009b; Marion et al. 2010);
investigation of avian and wildlife affected sites (Calderon 1991);
use of randomized control trial study design (Weidenmann et al. 2006; EC 2009a,
2009b);
use of prospective cohort study design (Calderon 1991; Dufour 1984; Marion et al. 2010;
Stevenson et al. 1953; Seyfried et al. 1985a, 1985b); and
use of retrospective cohort study design (Ferley et al. 1989).
In all of those epidemiology studies, statistically significant differences in the incidence of GI
illness (and in some cases other health endpoints such as respiratory illness) were observed
between swimmers and non-swimmers. In studies of POTW-impacted waters, three studies
identified an association of the increased incidence of GI illness with indicator density (Dufour
1 Seyfried et al. 1985b describes the locations of the study as being conducted "at various Ontario lakes." It unclear
whether or not this may include Lake Ontario, which would be considered a Great Lake and not an inland water for
the purposes of applying recreational criteria.
10
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1984; Seyfried et al. 1985b; Marion et al. 2010), and one study related indicator density to GI
illness risk via estimation of a no adverse effect level of indicator organism density
(Wiedenmann et al. 2006). No such relationships have been proposed for livestock and wildlife-
affected inland waters, although two studies (Seyfried et al. 1985a, 1985b; Wiedenmann et al.
2006) pooled illness rates and indicator densities without regard to fecal pollution source.
Calderon (1991) found no association between indicator level and incidence of GI illness in
recreational waters with exclusively nonhuman impacts for the indicators E. coli, Enterococcus,
fecal coliforms, and Staphylococcusdespite higher incidence of illness among swimmers than
non-swimmers.
The Epibathe (EC 2009a, 2009b) study of four beaches on inland waters in Hungary is difficult
to compare with the other epidemiology studies because the fecal pollution sources for the study
sites are not characterized and they employed a randomized control trial (RCT) study design. At
present, results from PC and RCT study designs cannot be used interchangeably, and no
techniques currently exist for converting their statistical outputs to allow meaningful quantitative
comparisons across study designs.
Based on these studies, E. coli (as measured by the culture-based method) seems a better index
of GI illness in swimmers using fresh recreational waters than Enterococcus (as measured by the
culture-based method), which appears to be the best predictor of such symptoms in marine
waters (see also reviews by Pruss 1998; Wade et al. 2003; Zmirou et al. 2003).
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2. Documents review
This section is comprised of a summary of findings (Tables 2 through 7) and a detailed review of
the documents (Section 2.2). Five out of eight reports (#1 to 4 and 6) are discussed individually
hereafter (Sections 2.2.1 to 2.2.5). The remaining reports (#5, 7, and 8), as well as the five
published research articles (#9 to 13), are discussed together in Section 2.3 to compile aspects of
methodology performance with respect to applicability of criteria to inland waters.
2.1. Summary of findings
Table 2. Study purpose, methodology, findings and limitations for the Final Report on the Experts
Scientific Workshop on Critical Research and Science Needs for the Development of Recreational
Water Quality Criteria for Inland Waters (WERF 2009)
Study purpose(s)
1. Determine if or how marine coastal and Great Lakes recreational water research
can be extrapolated to apply to inland waters
2. Identify additional research that could aid in the development of water quality
criteria applicable to inland waters in both the near and the longer term
Methodology
Findings are drawn from results of an experts workshop. Five major topic areas
indicators and pathogens, health effects, water matrix, sources, and
implementation realitieswere evaluated by separate teams of experts. Teams
were asked to assess the state of the science in their topic area and use that
information to assess the applicability of water quality criteria developed using
Great Lakes epidemiology studies for inland waters. Experts also identified and
prioritized data gaps, short-term, and long-term research needs.
Major findings
Indicators and pathogens group findings
The group found that insufficient evidence exists for direct extrapolation of
criteria based on Great Lakes studies for use for inland waters. The group
speculated that swimmers in POTW-impacted Great Lakes and inland waters
likely face similar risks but that the presence of non-fecal indicator sources at
sites could result in differences in the meaning of indicator levels at inland and
coastal sites.
Inland waters are generally more diverse, shallower (greater bacterial
redistribution), and better suited to tree growth (creating additional shading and
protection from sunlight inactivation) than coastal waters.
Soils and physical conditions in inland waters appear more conducive to extra-
enteric indicator growth than those of coastal waters.
Health effects group findings
The group recognized the imperative that new or revised criteria be developed
and the low likelihood that additional epidemiology studies will be conducted in
time for use in developing new or revised criteria. Under those circumstances,
the group generally supported the position that AWQC derived from Great Lakes
studies would likely be protective of public health at inland waters.
Epidemiology studies indicate that fecal source is more important than water
type (marine or fresh) or setting (inland vs. coastal) in determining health effects
related to swimming.
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Water matrix group findings
Inland water conditions that appear to favor indicator occurrence, growth and
resuspension from sediments were thought to be the following: (1) higher ratio of
sediment-water interface area to water volume for inland waters, (2) finer
sediment sizes typical in inland waters, (3) greater presence of wetting and
drying areas (per volume of water) at inland sites, and (4) relatively high
velocities and higher potential for resuspension at inland water sediment-water
interfaces.
Models appear to be the best avenue for exploring the impact of setting on
indicator and pathogen occurrence. Models that should be developed for this
purpose are regression models, mechanistic (watershed) models, and QMRA.
Sources group findings
Even within a particular fecal pollution source (human treated, human nonpoint,
livestock, companion animal, livestock) the relationship between indicator level
and health effects for different fecal pollutions sources differs with the level of
treatment of the waste, the proximity of the waste to the receiving water, the
prevalence and abundance of pathogens in the fecal pollution, and the
persistence of pathogens in the fecal pollution source relative to the persistence
of indicators.
Inland waters are believed to be in closer proximity to sources and more
influenced by on-site wastewater treatment facilities than coastal waters.
Implementation realities group findings
Approaches that have been used or could be used to introduce flexibility into
implementation of new or revised water quality criteria are the following:
o different criteria for beaches with different use patterns;
o discounting water quality measurements taken after rain events in concert
with implementing risk management strategies for protecting human health;
o using multiple metrics (sample analysis approaches and statistical
measures) for assessing water quality; and
o using temporary or permanent site-specific criteria.
Priority short- and longer-term research recommendations
Short-term
o Identify and quantify human pathogens in animal feces
o Examine relationships between qPCR and culture-based FIB
o Optimize and anchor QMRA models to observed health effects data
obtained from epidemiologic studies
o Develop QMRA tools for implementation of new AWQC
Longer-term
o Characterize fate and transport of animal pathogens in relation to
indicators
Conduct epidemiology studies in inland waters
Limitations
In many instances, findings were based on the best estimates or hypotheses of the
experts and could not be assessed against actual data because they were asked
to use their judgment in the absence of specific data. The major limitation/data gap
identified in the WERF report was the scarcity of epidemiology studies of inland
waters.
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Table 3. Study purpose, methodology, findings and limitations for Meeting Report: Knowledge
Gaps in Developing Microbial Criteria for Inland Recreational Waters (Dorevitch et al. 2010)
Study purpose(s)
Summarize the WERF Inland Waters Workshop Results (WERF 2009) in a peer-
reviewed, widely distributed publication
Methodology
Principal investigators distilled the experts workshop report into a peer-reviewed
publication and added contextual materials
Major findings
The physical and biological processes that are most likely to cause FIB to relate
to different risks in inland and coastal waters are the following:
o differences in source types, suites of potential pathogens in the source
materials, and severity of the diseases associated with the pathogens
typical of inland and coastal waters;
o closer proximity of inland waters to fecal pollution sources and lower
dilution of fecal pollution in inland waters than in coastal waters;
o differences in the potential for FIB growth in sediments typical of inland and
coastal waters; and
o differences in resuspension rates of sediment-associated indicators and
pathogens.
Application of coastal water-based criteria to inland waters is expected to result
in sporadic, mild illnesses at rates no higher and possibly lower than those
experienced in coastal waters. However, coastal and inland waters might pose
very different risks of severe illness.
Near-term research activities that will improve the understanding of indicator
performance in inland waters are the following:
o characterizing the spatiotemporal variability of indicator in inland waters by
assessing the literature, collecting field data, and/or developing
mechanistic models of indicator and pathogen fate and transport;
o developing and standardizing a sanitary survey tool to use for inland
waters;
o anchoring QMRA using data and relationships from epidemiological
studies;
o developing a database describing the setting-specific relationships
between molecular- and culture-based determinations of indicator
densities; and
o evaluating the viability of regression and mechanistic models for predicting
indicator density and water quality for inland waters.
Limitations
This study is subject to the same limitations as WERF (2009)
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Table 4. Study purpose, methodology, findings and limitations for Literature Review of
Assessment of the Applicability of Existing Epidemiology Data to Inland Waters (USEPA 201 Oa)
Study purpose(s)
To assess and compare the performance of FIB in inland and coastal settings
Methodology
A comprehensive literature survey was conducted to assemble studies reporting
the following:
epidemiology studies of inland waters;
occurrence of indicators in inland and coastal waters;
persistence of indicators in inland and coastal waters; and
co-occurrence of indicators and pathogens in inland and coastal waters.
Reports were reviewed, synthesized, and used in a qualitative comparison of
inland and coastal sites
Major findings
The data and relationships developed for Great Lakes waters studies, which are
affected primarily by POTW effluents, can be applied to inland waters that are
also affected primarily by POTW effluents.
For inland waters that are affected predominantly by sources other than POTW
effluent, the available science is not sufficient to support the extension of the
relationships developed in the Great Lakes because of potentially important
differences in fecal sources and hydrodynamics.
The reported occurrence ranges of FIB for coastal and inland waters are not
substantially different; indicator densities are widely variable in both settings.
Reported decay rates for inland and coastal freshwaters are not substantially
different. In all cases, predation, insolation, and the presence of sediments are
the most important determinants of indicator organism persistence.
Growth of E. coli has been reported in sediments of both inland and coastal
waters; insufficient data were obtained to assess the growth potential for
Enterococcus in inland and coastal waters.
As anticipated, no consistent correlations between indicator and pathogen
densities were observed, irrespective of setting.
Limitations
The study was based on a literature survey and significant data gaps exist,
including the following:
epidemiology studies of agriculture-affected coastal and inland waters;
quantitative assessments of the relative importance of resuspension in inland
and coastal settings;
quantitative assessment of the prevalence of different fecal pollution source
types in inland and coastal waters; and
large-scale studies of indicator densities as determined by molecular methods
and other alternatives to culture-based membrane filtration.
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Table 5. Study purpose, methodology, major findings and limitations for Sampling and
Consideration of Variability (Temporal and Spatial) for Monitoring of Recreational Waters (USEPA
201 Ob)
Study purpose(s)
Describe and quantify temporal and spatial variability of FIB density at inland
and coastal sites and the implications of variability for the design of sampling
plans
Methodology
A comprehensive literature survey was conducted to assemble physical and
biological processes at all relevant temporal and spatial scales, and to assess
FIB variability for coastal and inland waters.
Major findings
Temporal variability: discrete events (e.g., precipitation events, CSOs) produce
the greatest impact
o Other factors affecting temporal variability include the following: diurnal,
tidal, seasonal, and short-time-scale variability
Spatial variability: sample depth and along-stream sampling have the greatest
impact for coastal and inland sites, respectively. Other factors affecting spatial
variability are the following:
o For coastal sites: site features, along shore variations, depth below surface
at which samples are collected
o For inland sites: depth below surface at which samples are collected, and
cross-stream variations
Sanitary surveys and pilot monitoring are important components in the
development of beach monitoring plans. These activities establish the likely fecal
pollution sources and allow estimation of spatial variability in indicator density.
Monitoring considerations
o Pilot monitoring studies and sanitary surveys are the best tools available
for collecting data required to develop effective site-specific monitoring
plans.
o Where: area allowing most efficient characterization
o When: morning samples most conservative; sampling frequency is site-
specific, and providing best correlation between qPCR and culture-based
results
o How: approaches for choice of location and number of samples based on
site-specific constraints and historical data
Limitations
The study was based on a literature survey and limited to the studies reviewed.
Most of the studies reviewed reported results from studies of limited duration or
spatial extent. Extrapolating data from those studies to the diverse set of
recreational waters might not be warranted.
Few data are available to allow characterization of variability in qPCR FIB
estimates.
No studies assembled as part of the literature survey proposed protocols for
discounting or otherwise accounting for elevated indicator organism density
counts during rain events; flexibility in accounting for rain events was a stated
concern among stakeholders
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Table 6. Purpose, methodology, major findings, and limitations of draft final report. Quantification
of Pathogens and Sources of Microbial Indicators for QMRA in Recreational Waters (WERF 201 Oa)
Purpose(s)
Identify and address data gaps pertaining to loadings and concentrations of
waterborne pathogens and indicators in discharges to recreational waters that
are affected by fecal pollution
Compile, analyze and synthesize the data in QMRA models and waterborne risk
management frameworks
Methodology
Compilation of existing pathogen data and collection of a new, comprehensive
suite of bacteria, protozoa, and virus measurements for a variety of discharges-
of-concern to recreational waters across the U.S. These data can serve as
inputs for QMRA models.
Collection of additional pathogen and indicator data through field studies and
surveys of water and wastewater professionals.
Evaluation of microbial source tracking tools, such as the source identifier
bacteria Bacteroidales, for quantitative source apportionment and as a
component of QMRA
Critical review and analysis of QMRA as a risk analysis tool, determination of
the potential risks associated with measured discharges-of-concern, and
consideration of the role of QMRA for implementation of new recreational water
quality criteria.
Major findings
Data gaps pertaining to waterborne pathogens and indicators in fecally-impacted
discharges to recreational waters were identified and filled by targeted
monitoring campaigns in three geographic regions.
QMRA analyses revealed norovirus as the most dominant health risk followed by
rotavirus, regardless of setting (inland v. coastal).
Norovirus and Enterococcus both had significant correlations with a number of
pathogens in discharges.
Using qPCR data on the fecal source identifier Bacteroidales a new model can
predict the true amount of human fecal contamination in a water sample by
relating a human-associated genetic marker to a universal assay for fecal
sources. The model output can then be used to implement and evaluate
management options intended to restore microbial water quality.
Limitations
Inhibition and, for select pathogens, poor or widely varying recoveries must be
identified and overcome
Weather conditions prevented some monitoring events
Resource limitations did not allow for flow-weighted composite sampling
(instead, grab sampling was used), but for each sample the timing of the
sampling with respect to the hydrograph was estimated.
The inability of molecular-based methods to distinguish between dead and
viable cells is highlighted as a major limitation for risk assessment.
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Table 7. Purpose, methodology, major findings, and limitations of Methodology Performance and
Relevance to Applicability of Criteria to Inland Waters (compilation of findings from multiple
reports)
Purpose(s)
Describe important factors that influence enumeration method performance
Describe relevant differences in method performance between culture-based
and qPCR assays with respect to POTWs, solar inactivation, persistence and
other environmental factors
Review findings of studies comparing the relationship between qPCR and
culture indicator densities for inland and coastal sites.
Methodology
Review of relevant findings reports #5, 7, and 8, and peer-reviewed publications
#9 through 13 (Section 1.2.1)
Major findings
Accounting for bacterial viability and DMA persistence is an important
consideration when comparing culture-based methods with qPCR assays. This
leads to the following:
o qPCR cell equivalent counts are consistently greater than culture-based
CPU inventories due to the comprehensive detection of all DMA by qPCR
(commonly, the culturable fraction of cells is relatively marginal with
respect to the total count), prompting the design of live-only qPCR assays,
such as PMA-qPCR;
o accounting for different persistence in qPCR and culture targets when
evaluating site water quality; and
o coastal site morning samples analyzed by qPCR and culture-based assays
exhibit better correlations than samples collected in the afternoon (less
photoinactivation).
qPCR and culture-based results are well correlated at high densities but the
correlation is lost at low density due to high uncertainty of the qPCR assay in
this range and high variability in relationship between culture and qPCR density
at low cell densities. One study reviewed indicated better correlation between
qPCR and culture counts in Lake Michigan waters than in other waters including
inland lakes and rivers.
Quantitative polymerase chain reaction (qPCR) and cultural enumerations of
indicator organisms tend to be better correlated for fresh fecal material and very
poorly correlated for aged fecal pollution, indicators that have been subjected to
sunlight, and chlorinated waters.
qPCR Enterococcus and qPCR Bacteroidales methods are suitable for multi-lab
validation.
Culture-based bacterial densities are strongly reduced (2-5 orders of magnitude)
through wastewater treatment processes, especially by secondary treatment and
disinfection; qPCR inventories experience smaller reductions or remain
unchanged. This is probably due to the strong impact of disinfection on
culturable cells.
qPCR results are not greatly affected by insolation while culture-based methods
(e.g., membrane filtration [MF]) experience strong reduction by photoinactivation
during sunlight exposure. If coastal recreational waters receive greater fluxes
per volume of solar radiation (due to higher surface area-to-volume ratio
compared with streams), afternoon differences in qPCR and culture counts for
coastal waters are expected to be greater than for inland waters.
Inhibition under specific conditions (e.g., high salinity) can potentially affect the
qPCR assay and lead to lower counts. This inhibition differs among inland and
coastal sites and is not an intrinsic feature of either site type.
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Limitations
Data and experience with qPCR are limited; no single epidemiological study
reviewed for this report has produced dose-response curves for both molecular-
and culture-based methods.
Inhibition of the qPCR reaction likely differs among environmental waters and, at
present, is not thoroughly characterized.
qPCR assays vary from one study to another with respect to bacterial targets and
primer sets used, highlighting the need for harmonization/standardization for
comparison of molecular-based results.
Finite number and variety of sites sampled.
2.2. Detailed reviews
2.2.1. Final Report on the Experts Scientific Workshop on Critical Research and Science
Needs for the Development of Recreational Water Quality Criteria for Inland Waters
(WERF 2009)
In February 2009, EPA and WERF conducted the Inland Waters Expert Workshop with the
following objectives:
1. Determine if or how marine coastal and Great Lakes recreational water research can be
extrapolated to apply to inland waters.
2. Identify additional near- and long-term research that could aid in the development of
water quality criteria applicable to inland waters.
The workshop was organized around the following five thematic areas:
indicators and pathogens: biology, ecology, and methods;
health risks: epidemiology and risk assessment;
water matrix: hydrology, chemistry, geology, and modeling;
sources: human vs. nonhuman and point vs. nonpoint; and
implementation realities.
Workshop participants were assigned to one of the five topic areas, and each topic area group
produced a separate section for inclusion in the WERF report summarizing the workshop.
Findings in each topic area are described below.
Indicators and pathogens
The indicators and pathogens group explored differences in water quality at inland and coastal
sites and based their recommendations on those differences and the differences noted in
epidemiology studies. The water quality differences noted by the group are summarized below.
Coastal and inland water indicator dynamics are different. Coastal indicator dynamics are
more stable and less variable than those of inland waters. That is because inland waters
are more diverse than coastal waters and have smaller volumes and less dilution potential
than coastal waters.
The banks of inland waters are more favorable for tree growth, which could result in
greater shading of inland waters than coastal waters. Such shading is significant because
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sunlight inactivation is a significant factor in the extra-enteric persistence of indicator
organisms.
Inland waters are generally more shallow than coastal waters. The group relates the
difference to greater particle settling in inland waters than coastal waters. [Note that the
authors of this summary report question that assertion. Flows in inland waters are
characterized by higher velocities than those observed in coastal waters. Those higher
velocities can keep particles and particle-associated bacteria suspended. When tributaries
enter coastal waters, influent plumes disperse, velocities decrease, and particles tend to
settle.]
Inland waters are believed to be associated with soils and physical conditions that are
more conducive to FIB growth than the soils and physical conditions associated with
coastal waters. [Note that although the authors of this report find that assertion to be
reasonable, it is important to note that growth in coastal sediments and sands has been
documented in many studies, and no studies definitively support a greater propensity for
FIB growth in the inland environment than the coastal environment.]
After reviewing water quality and the dynamics of indicators in inland and coastal settings, the
group directly addressed the use of water quality criteria based on Great Lakes epidemiology
studies for inland waters. That group's assessment is that insufficient evidence exists for direct
extrapolation of criteria from Great Lakes studies for use in inland waters. The group speculated
that swimmers in POTW-impacted Great Lakes and inland waters likely face similar risks but
that the presence of non-fecal indicator sources at sites could result in differences in the meaning
of indicator levels at inland and coastal sites.
Health risks
The group contrasted the results of epidemiological investigations conducted for the following
types (setting) of water:
fresh and marine waters,
flowing and non-flowing waters, and
waters with different fecal pollution sources.
Comparisons of epidemiology studies for fresh and marine sites showed that indicator organism
levels do not relate to the same levels at either fresh and marine sites when culture-based
methods are used for measuring indicator organism density. The comparison also identified fecal
pollution source as more important than water type (marine or fresh) as a determinant of whether
the indicator level is associated with observed adverse health effects.
The group was unable to contrast studies for flowing and non-flowing waters because limitations
in study designs or differences between studies were too great to allow meaningful comparisons.
Comparisons of epidemiology studies conducted for waters with different fecal pollutions
sources were also hampered by differences in study designs and a relatively small number of
studies. In general, the group members hypothesized that differences in fecal pollution source are
likely more important than those in water quality and other features that differentiate inland and
coastal sites.
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Weighing the findings from the epidemiology studies described above, the group developed the
following two positions:
Position 1applying the results from the Great Lakes studies to inland flowing waters is
not supported by the scientific literature because directly comparable studies have not
been conducted. It is unknown whether such application is underprotective of public
health.
Position 2applying the results from the Great Lakes studies to inland flowing waters is
a reasonable step based on supporting information in the literature and approaches taken
worldwide and is unlikely to result in the underprotection of public health.
The group recognized the need for new criteria to be developed and the low likelihood that
additional epidemiology studies will be conducted in time for use in developing new or revised
criteria. Under such circumstances, the group generally supported position 2, stating, "It is the
opinion of the Health Risks Group that water quality criteria derived from Great Lakes studies
would likely be protective of public health at inland waters."
Water matrix
The group noted the importance of fecal pollution source, water physical and chemical
properties, microbial ecology, and hydraulics in the association of indicator organisms with
health effects. Considering those factors, the group focused on the potential for settling,
regrowth, and resuspension of indicators in inland waters, and the use of predictive models for
evaluating differences between inland and coastal sites.
Inland water conditions that appear to favor indicator occurrence, growth, and resuspension from
sediments were thought to be (1) higher ratio of sediment-water interface area to water volume
for inland waters, (2) finer sediment sizes typical in inland waters, (3) greater presence of
wetting and drying areas (per volume of water), and (4) relatively high velocities and higher
potential for resuspension at sediment-water interfaces. The group acknowledged that additional
research is required before the effects of those features on the loads of non-fecal indicators is
known.
The group discussed the use of predictive models for evaluating differences between coastal and
inland waters. Three types of models can be used for systematic evaluation of differences
between inland and coastal sites:
regression models,
mechanistic models, and
QMRA models.
Each of those models is associated with limitations. Regression models have, to date, been
formulated on the basis of relatively limited sets of water quality and physical condition data.
That limits the applicability of the models for sites outside those used for developing the model.
Debate remains regarding the most appropriate independent variables, and it is possible that
those variables differ between sites, further reducing the generality of regression models.
Mechanistic models can be developed at many scales and including/excluding many processes.
To allow comparison of inland and coastal waters, mechanistic models should include the
following:
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three-dimensional models of indicator transport for coastal sites, inclusive of wind-driven
flows;
accurate modeling of dilution, turbidity, and shading;
association of inland sites with finer particle sizes and greater association of
microorganisms with particles; and
higher organic content and potential for regrowth for inland sites.
Although the Water Matrix Group did not explicitly note it, the development of such models
would require large amounts of data, additional data collection, and the simulation of multiple
scenarios or development of techniques that would allow the generalization of results of
individual simulations.
The group noted that QMRA modeling would have to overcome great uncertainty in parameters
of the risk models. To lend credibility to QMRA modeling activities, the group strongly
recommended studies in which QMRA models are anchored to epidemiology study results. Once
anchored, QMRA would provide an avenue for the investigation of phenomena for which other
modeling activities are less suited, including exploration of relative risks during events and of
worst-case scenarios.
Sources
The group noted that even within a particular fecal pollution source (i.e., human treated, human
nonpoint, livestock, companion animals, and livestock) the relationship between indicator level
and health effects for different fecal pollution sources differs with level of treatment of the
wasteincluding the proximity of the waste to the receiving water, the prevalence and
abundance of pathogens in the fecal pollution, and the persistence of pathogens in the fecal
pollution source relative to the persistence of indicator organisms. The prevalence and
abundance of both FIB and pathogens varies widely between fecal pollution sources and within
each fecal pollution source.
The Sources Group stated that because the prevalence of on-site wastewater treatment (septic)
systems, which they considered to be nonpoint sources of pollution, is much greater for inland
waters than for coastal waters, these human fecal pollution sources are more associated with
inland waters than coastal waters. Note that septic systems differ widely in their design and
operation and likely result in fecal pollution loads that vary widely. Additionally, runoff from
urbanized areas with high proportions of impervious surface area differs from agricultural or
rural areas, although the explicit implications of the differences between rural and urban runoff
were not stated.
The group related differences between inland and coastal water settings to differences in
proximity of fecal pollution sources to receiving waters, differences in pathogen and indicator
density and prevalence in source materials, differences in loading during rain events, and
differences in land use. The group hypothesized that coastal waters are generally more associated
with urbanized land use, higher impervious surface areas, and point and diffuse human pollution
sources than inland waters. However, the group acknowledged that inland waters comprise a
diverse group and that the association of coastal and inland waters with specific sources of fecal
pollution and characteristics are hypotheses.
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The group concluded by stating that knowledge gapsparticularly for the abundance,
prevalence, and pathogenicity of pathogens in livestock and wildlife wastes, are so profound and
the inherent variability in nonpoint source-affected systems is so great that it could not assess
whether water quality criteria based on Great Lakes/coastal studies could be extrapolated to
inland waters.
Implementation realities
The group focused on flexibilities that are present in non-U.S. beach programs and might be
considered for implementation with new or revised AWQC. Specific needs for flexibility should
recognize the following factors/elements:
water quality and risk vary dramatically with rain events;
different fecal pollution sources pose different hazards; and
the proportion of non-fecal, resuspended organisms varies with site type.
The current AWQC (USEPA 1986) implementation provides flexibility via use of different
monitoring schemes for assessing water at beaches with different levels of usage, and through
provision of an off-ramp by which site-specific water quality criteria could be established on the
basis of sanitary surveys and epidemiology studies. Additionally, states can designate specific
classes of waterbodies or specific circumstances for different, scientifically defensible water
quality standards. Such a designation could be made for waters known to be affected primarily
by animal sources or for temporary changes in microbial water quality criteria following rain
events.
Flexibility is provided in World Health Organization (2003) standards by using sanitary survey
findings in selecting water quality criteria appropriate for a specific site. Recreational sites
without human fecal pollution sources and low bather density are considered to have good water
quality at indicator densities higher than those for sites with known human fecal impacts or high
bather densities.
European Union bathing water quality standards (EP/CEU 2006) provide flexibility through
discounting of samples collected during short-term pollution events. Within this framework, up
to 15 percent of the total samples at a site could be disregarded for classification purposes
because of short-term pollution during the last assessment period. The Implementation Realities
Group notes that inland waters are most influenced by wet weather events because they are more
closely associated with urbanized areas. Note that this assessment is somewhat at odds with that
of the Sources Group.
The Implementation Realities Group noted that beach sampling and water quality assessment are
conducted in the context of other regulatory programs, including NPDES permitting,
303(d)/TMDL use attainment assessments, and BEACH Act monitoring. Monitoring needs and
realities differ for these programs and techniques and methods for assessing water quality also
differ. Flexibility in the overall regulatory context might be provided with the issuance of water
quality criteria on the basis of multiple methods for counting indicator organisms, or through the
provision of multiple statistical approaches for developing monitoring plans and assessing results
of microbial water quality sampling.
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Research priorities
After assessing the state of the science and knowledge gaps in each topic area, the expert groups
developed prioritized lists of suggested research activities intended to provide improved
information for development or extension of criteria for inland waters. The priority short- and
longer-term research activities proposed by the workshop participants is presented in Table 8,
and a comprehensive list is presented in Table 9.
Table 8. Priority research activities from the 2009 Inland Waters Workshop (WERF 2009)
Time frame
Short-term
Longer-term
Research
Identify and quantify human pathogens in animal feces
Examine relationships between qPCR and culture-based FIB
Optimize and anchor QMRA models to observed health effects data obtained from
epidemiology studies and develop QMRA tools for implementation of new AWQC
Characterize fate and transport of animal pathogens in relation to indicators
Conduct epidemiology studies in inland waters
Table 9. Comprehensive list of proposed research activities from the 2009 Inland Waters
Workshop (WERF 2009)
Group
Short-term research priorities
Longer-term research priorities
Indicators and
Pathogens
Examine relationships between
qPCR- and culture-based FIB and
develop a database of results to date
of other reliable potential new
monitoring methods
Conduct studies on watershed
assessment information to be used as
input for site-specific water quality criteria
Investigate the potential forspeciation of
enterococci to identify fecal-specific
strains (preferably human) from
environmental strains, and then apply
results to future epidemiology studies
Conduct epidemiology studies that take
into account urban runoff and nonpoint
sources of fecal contamination. Include
the use of culture-based and molecular-
based analytical methods. Include
sensitive populations (particularly
children).
Conduct epidemiology studies
incorporating the measurement of
pathogens of interest along with indicators
to determine the correlations of these
organisms and to better understand their
associations with diseases at downstream
recreational locations
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November 2010
Group
Short-term research priorities
Longer-term research priorities
Health Effects
Optimize and anchor QMRA models
to epidemiology studies
Incorporate source characterization
methods into ongoing epidemiology
studies
Optimize and standardize qPCR
methods and enhance their
interpretation
Conduct meta-analysis of
epidemiology studies by source
Conduct further epidemiology research to
identify how much uncertainty exists in
using the results of epidemiology studies
conducted in Great Lakes and coastal
settings to establish criteria for inland
flowing waters
Water Matrix
Apply model-driven nowcasting or
forecasting (or both) in current
epidemiologic studies to determine a
relationship of model variables to
health outcome
Further develop and test regression
models in inland waters (at rivers with
different morphologies from those in
Ohio, Georgia, and Kansas)
Focus on prior epidemiology studies
to build models after the fact and
compare the results from such
retrospective models to the observed
human health effects
Include an in-depth evaluation of
target microbe/pathogen sources and
environmental conditions in
epidemiology studies to evaluate the
sources and parameters needed for
coupling health outcomes with model
output
Evaluate reverse QMRA for its
applicability in developing site-
specific criteria
Apply data mining activities to identify
data gaps that limit application of
models and identify longer-term
research goals
Use modeling approaches to characterize
source impacts as an integral part of the
design of all recreational water
epidemiology studies
Further develop and test regression
models in all types of inland waters to
clarify their applicability, limits, and future
research needs
Focus on developing the fundamental
understanding and knowledge needed for
establishing mechanistic models
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Inland Waters Summary Report
November 2010
Group
Short-term research priorities
Longer-term research priorities
Sources
Identify and quantify human
pathogens in animal feces
Identify and quantify human
pathogens in various types of on-site
systems, especially during wet
weather and including disinfection
efficacy of systems and their rate of
failure
Identify fate and transport of important
human pathogens identified in animal
feces
In future and ongoing epidemiology
studies, include agricultural, nonpoint
source runoff, measure human pathogens
identified in animal feces
In characterization of land-use and
sanitary surveys, define consistent
template and quantify important inputs
In developing water quality safety plans
and developing best management
practices (BMPs), determine recreational
component of water safety plans involving
EPA, utilities, scientists, and community
collaboration
In developing water quality safety plans
and developing BMPs, undertake
research to quantify effectiveness of
various BMPs and their applicability to
various watershed scenarios
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Inland Waters Summary Report
November 2010
Group
Short-term research priorities
Longer-term research priorities
Implementation
Realities
Perform analyses of all existing
inland water epidemiological data
(domestic and international),
including multiple sub-analyses (e.g.,
flowing versus quiescent, source
type, relationships between
indicators, relationships of indicators
to human health risk)
Develop more science to understand
regrowth or resuspension of
enterococci in sediment of inland
flowing waters
Research the effects of prolonged
holding times on microbiological
analytical results
Develop early communication on
aspects or options of implementation
guidance and national level
expectations in terms of adoption for
inland waters
Use longer averaging periods for
assessment purposes to
deemphasize short-term excursions
Consider modification or use
suspensions during defined high-flow
conditions
Consider developing site-specific
criteria based on QMRA or other
methods
Designate a new designated use (or
uses) on the basis of physical
waterbody characteristics or the
types of activities that a waterbody is
used for (shallow water use or
secondary contact use)
Develop a guidance document to
facilitate criteria adoption by states
Develop data to quantify risk in waters
affected by nonhuman sources
Develop a flowing water sample design on
the basis of stream characteristics
Develop a translation between current
criteria and any new criteria
Standardize methods including an
evaluation of method robustness and a
certification program for regulated
laboratories
Conduct studies evaluating the impact of
sediment-borne resuspension events
especially during high-flow periods
Conduct studies to determine appropriate
indicators for each CWA purpose and a
method to bridge current assessment
criteria and methodologies to new ones
Develop data on pathogens/infectivity and
exposure information for input to site-
specific QMRA models
Use QMRA for estimating health risks and
developing appropriate and detailed
exposure pathways for inland waters
2.2.2. Meeting Report: Knowledge and Gaps in Developing Microbial Criteria for Inland
Recreational Waters (Dorevitch et al. 2010)
As described in Section 2.2.1, in February 2009, WERF with support from EPA planned and
conducted a workshop to explore similarities and differences between inland and coastal waters.
That workshop resulted in a peer-reviewed publication (Dorevitch et al. 2010) describing the
workshop findings and knowledge gaps related to the extension of criteria developed for coastal
to inland waters. In the following section, the report findings are summarized. Differences
between inland and coastal waters with the potential to necessitate different criteria are
summarized first. Then research questions and a research agenda are presented. Note that the
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Inland Waters Summary Report November 2010
study is a synthesis of the full report (WERF 2009) from the workshop (Section 2.2.1). Because
the authors of the study interpreted and prioritized elements from the full study, the peer-
reviewed version of the report summary is also reviewed in this report.
Differences between inland and coastal waters
Dorevitch et al. (2010) identifies the following three assumptions that must be made to extend
AWQC developed for sewage-affected coastal sites to inland sites:
1. Similar densities of FIB reflect a similar risk in inland and coastal settings, presumably
because they reflect a similar exposure to pathogens of similar infectivity and virulence.
2. Hydrogeochemical differences among inland lakes, rivers, and coastal waters have
nondifferential effects on the transport and fate of indicators and pathogens.
3. The criteria derived from the studies conducted at sewage-affected coastal beaches
protect against illness in inland settings, where the predominant source could be wildlife
or agricultural animals.
Foremost, the report notes that the fecal pollution source is the primary site feature determining
the risk of illness from recreational exposure. The authors assert that inland waters are
predominantly in rural areas and have a greater likelihood than coastal waters of being affected
by agricultural or wildlife fecal pollution sources. Further, pathogens present in livestock and
wildlife fecal wastes differ in both abundance and human health effects from those present in
sewage. Zoonotic agents can differ from pathogens of human origin either in their ability to
initiate infection or in the hazard they pose. The authors of this summary report note that
although the reviewed report notes the importance of source and etiology of illnesses arising
from recreation, it does not quantify the extent to which coastal and inland waters are affected by
different fecal pollution sources. Though many river miles are in rural areas, rivers are loaded by
POTWs, combined sewer overflows (CSOs), septic systems, and other human sources. For some
streams during dry periods, POTW effluent can constitute a significant portion of flow.
Likewise, animal sources affect coastal sites. For example, coastal counties of the Great Lakes
states support large populations of dairy cattle, while coastal counties on the Delaware and
Chesapeake bays are locations of intensive chicken production (NASS 2010). Shorebirds and
dogs are also considered important fecal pollution sources for coastal waters.
Dorevitch et al. (2010) identifies indicator growth and mobilization in sediments as a significant
potential difference between inland and coastal water indicator performance. Specifically, the
report implies that the inland water sediment and soil environment is more favorable to indicator
organism growth than the coastal environment and that inland water hydraulics generates greater
suspended indicator loads than coastal hydraulics. Inland water sediments are believed to
generate larger FIB loads because the extra-enteric growth conditions for FIB are thought to be
most favorable at the water-sediment boundary, and the ratio of the water-sediment boundary
length to the stream cross-sectional area is higher than that for coastal sites. The study also
asserts that indicator organisms harbored or growing in sediments are more likely to be
resuspended into the water column due to more favorable hydraulics for resuspension in inland
waters because boundary layers (indicative of the shear stress on bottom sediments) occupy a
larger fraction of inland water volume than of coastal water volume. Together, those phenomena
result in a larger proportion of indicators in inland waters arising from non-fecal sources than the
proportion in coastal waters. Thus, for inland and coastal sites with the same fecal pollution
source, an indicator density observed in inland water is likely to correspond to a different
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Inland Waters Summary Report November 2010
presence of fecal pollution and a different risk than for the coastal water at which the same
indicator density is observed. Such a decoupling of indicator organisms from fecal pollution
sources represents a significant difference in indicator performance for inland and coastal waters.
Hydrogeological differences might influence indicator performance in inland and coastal waters.
First, fecal pollution sources are often closer to receiving waters for inland water than for coastal
waters. Given the smaller water volumes typical of inland waters, less dilution of the fecal
pollution is expected for inland waters than for coastal waters. This finding does not pose a
difficulty in use of indicators for inland and coastal waters; the higher indicator densities
observed in inland waters are related to higher fecal pollution densities and higher public health
risk. Increased risk is expected to be associated with proximity to the fecal pollution source.
Decreased risk is expected to be associated with exposure to more dilute fecal pollution.
Indicators shed by the bathers can be diluted less in inland waters than in coastal waters. All
other factors being equal, higher indicator densities are associated with higher fecal pollution
concentration and increased risk.
An additional difference in hydrogeology for inland and coastal waters with significance to
indicator performance is the flow typical of the settings. Inland waters are subject to highly
variable volumetric flow rates, bottom shear stresses, and turbulence. Those parameters are less
variable for coastal waters. Advection dominates fecal pollution transport in flowing inland
waters, whereas advection via longshore currents, other large-scale currents, or wind-driven
water flows are the drivers behind most transport of fecal pollution into and out of coastal sites.
This difference results in more extreme variation in indicator densities during storm events for
inland waters than for coastal waters, as observed by Nevers et al. (2007) for coastal streams near
Great Lakes beaches. Furthermore, as described above, turbulence can promote decoupling of
indicator density from fecal pollution sources.
Critical research questions and a research agenda
The report proposes four areas encompassing the research that should be conducted to improve
the understanding and estimation of health risks arising from recreation in inland waters. The
four areas are presented below, along with suggested short- and long-term research activities for
closing data gaps and improving understanding.
1. Microbial indicators as predictors of risk
The spatiotemporal variability and determinants of FIB need to be characterized for
hydrologically diverse settings. Although not detailed in the report, these diverse settings include
small rural streams, small urban streams, large flowing waters, and impounded waters. Short-
and long-term research suggested include meta-analysis of epidemiological relationships
developed for waters affected by different fecal pollution sources (short-term), and mechanistic
fate and transport modeling of FIB s for the range of water types expected to be important as
recreational waters.
2. Fecal pollution sources as predictors of pathogen exposure and health risk
In the topic of fecal pollution sources as predictors of pathogen exposure and health risk, short-
term research activities suggested in the report are development of a sanitary survey tool for use
in inland water epidemiology and QMRA studies, optimization and anchoring of QMRA by
means of data and relationships from epidemiology studies, and field sampling of feces from
farm animals and wildlife to quantify the occurrence and dynamics of pathogens of human
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concern. In the long term, the report suggests that epidemiology studies should be conducted at
inland sites with different dominant fecal pollution sources. Epidemiological studies should
differentiate between pathogens posing different hazards, particularly those associated with very
serious health outcomes (e.g., zoonoticE1. coli O157:H7).
3. Molecular methods for water quality testing
Given the likelihood that molecular methods will be employed in new AWQC, molecular
methods should be better understood and optimized. A database describing the relationships
between molecular- and culture-based determinations of indicator densities should be developed
on the basis of findings reported in the technical literature. Given the differences in transport and
fecal pollution loading for inland and coastal waters, that database would likely include
relationships for a wide variety of settings ranging from small inland waters to large inland
waters to coastal sites. The persistence of molecular method targets should be established. This
step is critical given that one performance criterion of indicator organisms is persistence similar
to that of the pathogens they indicate. Quantitative PCR methods, particularly for source-specific
markers, should be optimized, standardized, and applied in epidemiology studies.
4. Other approaches for predicting inland water recreation health risks
The other approaches suggested by Dorevitch and colleagues for predicting risks include
predictive modeling (such as Nowcast forecasting) and QMRA. Regression models have been
demonstrated to be more predictive of whether an AWQC will be exceeded than simple use of a
prior day's indicator density for coastal sites. Flow models can be used to improve regression
models, though real-time multidimensional modeling of coastal sites has not been demonstrated
to date. Modeling research activities suggested include evaluation of the viability of regression
models and mechanistic models for risk management and as supplements to FIB monitoring for
inland waters. There are several indications that regression and mechanistic models are feasible
for use in inland water risk management. Monitoring and forecasting systems are in use for
managing risks to drinking water systems with surface sources. Numerous well-tested
contaminant transport models are available for mechanistic modeling of FIB or pathogens in
streams; given the hydraulics and geometry of streams, these models are much less complex than
flow models of coastal sites and have the potential for use in real time. Challenges to use of
regression and mechanistic models include the following:
sporadic nature of fecal indicator and pathogen loads to streams;
knowledge gaps regarding FIB and pathogen growth in sediments and resuspension;
incomplete knowledge of the persistence of the microorganisms in diverse inland water
settings; and
need for sensors and protocols for collecting real-time data for use in predictive models.
The QMRA framework is flexible and can be used to relate indicator and pathogen fate and
transport to risk. When used in tandem with epidemiological analyses, QMRA can add context to
epidemiology study findings. In the absence of epidemiology studies (as is currently the case for
inland waters), QMRA can be used to develop estimates of human health risk that can be
compared to those observed for coastal waters. To be used in either of those modes, QMRA must
have credibility with the scientific community and must provide sufficient data to allow realistic
risk estimates specific to the geography, biology, and hydrology of inland waters. The report
advocates anchoring QMRA (retrospective studies) as a short-term research need. Such an
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exercise would necessitate generating improved models and can be used to advance the
credibility of QMRA with the scientific and policy communities.
Report conclusions
Dorevitch et al. (2010) conclude that the distinction between inland and coastal waters is less
important than differences in the fundamental processes and variables of the systems. The
processes and variables include the scale of the waterbody, the fecal pollution source(s),
indicator and pathogen dynamics in sediments, and other factors related to the transport and fate
of indicators and pathogens. Of particular importance is a clear understanding of the proportion
of indicators that is directly related to a specific fecal pollution source and the proportion not
related to fecal pollution sources and thus indicative of a different and likely lower risk.
The authors reason that applying criteria derived on the basis of epidemiology studies of coastal
sites to inland waters should result in sporadic mild illnesses at rates no higher and possibly
lower than those experienced in coastal waters. However, coastal and inland waters might pose
very different risks of severe diseases such as hemolytic uremic syndrome arising from exposure
to E. coli O157:H7 and other pathogenic E. coli strains. The origin of those different risks is the
difference in the dilution capacity of typical inland waters and coastal waters, as well as the
difference in pathogenic organisms in sources typical of coastal and inland waters.
2.2.3. Literature Review of Assessment of the Applicability of Existing Epidemiology
Data to Inland Waters (USEPA 201 Oa)
Before the 2009 WERF workshop whose findings are described above (Dorevitch et al. 2010;
WERF 2009), background material was assembled describing and comparing the occurrence,
fate and transport of indicator organisms in inland and coastal waters. After the workshop, the
draft report was revised to expand upon sections pertaining to epidemiological data and health
effects. The document (USEPA 2010a) underwent a second round of revisions in August 2010.
That version of the report is reviewed below.
The purpose of the report is to assess and compare the performance of indicators in inland and
coastal waters. The authors compare the performance of indicators in coastal and inland waters
on the basis of the following features:
demonstrated correlation with health risk;
similar or greater survival time than the target pathogen;
similar or greater transport than the target pathogen;
presence in greater numbers than the pathogen; and
specificity to a fecal source or an identifiable source of origin.
Indicators demonstrate all those features for both inland and coastal waters.
The report presents data and analysis from the peer-reviewed literature grouped into three
sections (1) epidemiology and modeling studies of the health effects associated with recreation in
surface waters; (2) the occurrence and variability of indicators in coastal and inland settings; and
(3) the persistence and growth of indicators and the association of indicators with pathogens.
Absent from the report are discussion of differences in resuspension for typical inland and
coastal waters, discussion of differences in typical fecal pollution sources for different settings,
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Inland Waters Summary Report November 2010
discussion of suites of pathogens characteristic of different fecal pollution sources, and
evaluation of the role of dilution in indicator performance.
Epidemiology and modeling studies
To date, epidemiology studies have demonstrated correlations of health risk with indicator level
only for waters primarily affected by POTW discharge. For freshwater sites, studies have
demonstrated association of health risk with indicator level for E. coli enumerated by cultural
methods (Dufour 1984; EC 2009a, 2009b; Marion et al. 2010) and for Enterococcus enumerated
by qPCR (Wade et al. 2006, 2008). Among those studies, the only two that are potentially
directly comparable are the Dufour and Marion studies, because both used the prospective cohort
(PC) study design and the same illness definition. Direct comparison of the results of those
studies should be done cautiously, because the health effects relations in the Dufour study are
based on seasonal averages of indicator densities whereas in the Marion study they are based on
individual days' samples taken at an inland reservoir. In general, the results of both
epidemiology studies indicate that health effects observed in the two studies are comparable,
despite the studies being conducted more than two decades apart (the GI definition was the same
in both studies).
Other epidemiology studies will require analyses and conversion of data prior to comparison. For
example, both health effects and water quality data from randomized control trial (RCT)
epidemiology studies could require conversion for comparison with PC epidemiological health
effects data.
Modeling provides an alternative to epidemiology studies for assessing health risks associated
with recreational use of surface waters. As noted above, epidemiology studies provide the
firmest basis on which to develop criteria. However, in the absence of epidemiology studies,
modeling studies could provide a means for evaluating health risks. Modeling studies described
in the USEPA (2010a) include QMRA and watershed modeling approaches.
Recently published QMRA studies (Schoen and Ashbolt 2010; Seller et al. 2010a,b) have linked
indicator level to the occurrence of pathogens for non-POTW sourcesincluding cattle manure,
swine manure, chicken manure, and gull droppings. Those studies rely on pathogen and indicator
occurrence and abundance as reported in the literature for estimating the pathogen suite and
resulting illnesses rates associated with ingestion of runoff from livestock operations or from
beaches contaminated with gull droppings. Those models are stochastic and account for the
variability in the occurrence and abundance of pathogens and indicators in fecal sources. The
QMRA models indicate that, at a given indicator level, recreation in waters affected by cattle
runoff poses a similar risk to recreation in waters affected by human fecal pollution sources,
whereas recreation in swine-, chicken-, and gull-affected waters poses a significantly lower
health risk. The results will be refined in future studies to account more accurately for fate and
transport processes and manure treatment. The finding that different fecal pollution sources have
different risks at the same indicator level does not consider inland and coastal sites to be
substantially different. Rather, it is presumed that the source, not the setting, is the critical feature
of a site.
Watershed modeling is a related but alternative modeling technique that can be used as an
alternative to epidemiology studies for assessing health risks association with recreation in
surface waters. Like QMRA models, watershed models rely on data collected from external
sources as input for models that predict net pathogen loads watersheds discharge to receiving
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waters. The watershed models can be used in developing sampling schemes, in assessing
differences of risk in different portions of a watershed, or in comparing the contribution of
different fecal pollution sources to the pathogen loads to receiving waters. Because the models
are site-specific, they might have a greater role in implementing new or revised criteria than in
developing the criteria.
FIB occurrence in inland and coastal waters
Nearly all available data on the occurrence of FIB are presented as ranges, not as statistical
distributions. Accordingly, more meaningful comparison of ranges of indicator densities with
metrics such as geometric means, measures of spread and of skew in distribution of occurrence,
could not be used. Moreover, studies were limited to relatively few waterbodies and each study
had different designs and objectives, so how representative their data are with respect to the
overall distribution of FIB among inland and coastal waters is uncertain. Thus, comparisons of
the occurrence of indicators in coastal and inland waters were considered screening level and
were made on the basis of reported ranges.
The report presented indicator occurrence density ranges for E. coli, enterococci, fecal coliforms,
total coliforms, and fecal streptococci. To allow comparison across setting types, ranges for the
following setting types were determined:
coastal freshwaters;
coastal marine waters;
estuarine;
inland flowing, main;
inland flowing, small; and
inland non-flowing.
Coastal marine sites exhibited the highest variation in both E. coli and Enterococcus densities,
somewhat contrary to expectations. Coastal waters are subject to much greater dilution than
inland waters and are farther from fecal pollution sources than typical inland waters. Given the
limitations of the occurrence data, the report concludes that the occurrence of indicators in inland
waters and in coastal waters is not substantially different. It is important to note that none of the
studies used in developing the occurrence ranges attempted to ascertain the source of the
indicator organisms.
Growth and persistence of FIB
Indicator survival curves typically exhibit shoulder behavior (the shoulder being the initial curve
before the exponential portion, representing that damage has to accumulate to a certain level
before cells begin to die), followed by first-order decay. The factors most important in
determining the decay rate are presence of sediments, insolation, and the presence/absence of
predators. Less significant factors are temperature and salinity. Nutrient availability and pH also
influence persistence, but they do not vary sufficiently among waters to result in significant
differences in persistence among sites.
Fecal indicator bacteria growth has been observed in coastal and inland settings and in both large
and small streams. Fewer studies have reported growth of enterococci than of E. coli and fecal
coliforms; however, it is not certain whether this is because enterococci growth is less prevalent
than that of the other indicators or whether there are fewer studies on enterococci. The presence
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Inland Waters Summary Report November 2010
of sediments is a primary factor in determining whether growth is observed. Because inland and
coastal waters differ in the sediments present and the ratio of the sediment-water interface area to
the water column volume, that difference could result in a different proportion of indicators in
inland waters arising from sediments than the proportion in coastal waters. The proportion of
indicators attributable to resuspension from sediments is determined by the density of indicators
in the sediments and the resuspension of the indicators via turbulence arising either from shear
stress at an inland water streambed or from wave action or tidal processes in coastal sites.
Reported E. coli inactivation rates do not differentiate indicator performance in Great Lakes
waters from that in inland waters. In both water types, indicator decay rates depend on the same
physical factors and are widely variable. Contrary to expectations, reported inactivation rates for
marine and freshwaters overlapped. Studies have established decreased persistence of E. coli
with salinity, so the overlapping ranges indicate that the combination of factors determining
survival are such that their net effect is inactivation rates spanning the same range. Fewer studies
were found providing Enterococcus inactivation rates. The studies reviewed in USEPA (2010a)
indicate that the same factors govern the persistence of enterococci in inland and coastal waters
and that persistence is comparable in the two settings.
Co-occurrence of FIB and pathogens
At the time that report was completed, only two epidemiology studies have yielded health effects
relationships for culture-based indicator enumeration in inland waters and there are no available
studies that have established health effects relationships for inland waters based on qPCR.
Therefore, the health effects associated with inland waters and coastal waters must be deduced
either from a direct association of pathogens and indicators or from an association of indicators
and pathogens with fecal pollution sources. In USEPA (2010a), studies attempting to correlate
pathogen and indicator occurrence were reviewed. The relevant studies included studies of
bacterial, protozoan, and viral pathogens for inland and coastal waters. In short, co-occurrence
and correlation between pathogens and E. coli and Enterococcus were not observed for any
setting. Though not reported, it is clear that pathogen variability differs from that of indicators,
even for a given fecal pollution source. Other processes, including the following, can cause
pathogen-to-indicator ratios to vary:
different removal rates of indicators and pathogens via settling in flowing and non-
flowing settings;
different removal rates of indicators and pathogens via ultraviolet (UV) inactivation
(assuming the incident UV radiation is different in coastal and inland settings because of
shading or other features); and
different sources or loading rates associated with different settings.
2.2.4. Sampling and Consideration of Variability (Temporal and Spatial) for Monitoring of
Recreational Waters (USEPA 201 Ob)
As noted in Section 1.1.2, stakeholders have expressed concerns over both science and the
application of new or revised AWQC to inland waters. Concerns repeatedly expressed by
stakeholders are (1) sampling and interpretation of results for inland waters at which there is the
potential for recreation but recreation does not occur, and (2) concerns that samples taken during
or shortly after rain events, when indicator densities are extremely high, will unduly influence
water quality assessment. Data and interpretations germane to those concerns are presented in
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Sampling and Consideration of Variability (Temporal and Spatial) for Monitoring of
Recreational Waters (USEPA 201 Ob). That report describes the temporal and spatial variations
in indicator densities for both inland and coastal waters and at all relevant spatial and temporal
scales.
Indicator variability in inland and coastal waters
A full review of the findings regarding indicator spatial and temporal variability provided in
USEPA (201 Ob) is outside the scope of this report. In brief, a review of the literature produced
the following findings:
Regardless of site type, the greatest variations in indicator density arise from rain events.
Temporal variability, from greatest to least, is as follows: Event variability (rain events) >
diurnal variability > tidal-time-scale variability (coastal sites only) > monthly/seasonal
variability (considering only the recreational use season) > short-time-scale variability
(for samples taken at knee depth and greater).
For coastal sites, sources of spatial variability, from greatest to least, are as follows:
variation with depth of sample collection > variation with site features such as point
sources or features inhibiting mixing > along-shore variation > variation with depth
below the water surface where sample is collected.
For inland sites, sources of spatial variability, from greatest to least, are as follows:
along-stream variation > variation with depth below the water surface where sample is
collected > cross-stream variation (i.e., downstream of the mixing zone for point
sources).
Developing monitoring plans
Monitoring plans chosen for specific sites should be designed on the basis of the variability in
indicator density anticipated at that site. Thus, data should be collected before monitoring
scheme development to quantify spatial and temporal variability. Two vehicles suggested for
collecting those data are sanitary surveys and pilot monitoring activities. Perhaps most important,
sanitary surveys include collection of data on the fecal pollution sources with the potential to
affect a site and the route by which fecal pollution could be delivered to the site. For coastal
waters, transport modeling can be complex, given variability in currents, wave-generated
turbulence, and such. For inland waters, identification of sources can be complex because many
inland water fecal pollution sources are diffuse.
None of the studies reviewed in USEPA (201 Ob) directly addressed the consideration of
extremely high indicator densities during rain events. As noted in that report, extremely high
indicator densities can arise in both inland and coastal waters during rain events, although given
the lower dilution and proximity to sources of inland waters, the impact on inland waters is
expected to be greater than that on coastal waters.
Inland sites can require different monitoring strategies because of their accessibility, length, and
frequency of use. Ideally, the number of samples is chosen using a variation of power analysis,
with the detectable difference related to the acceptable range in risk or a range of risks that is
measurable within the overall population. Because of cost or logistical considerations, beach
managers might not be able to sample with the density or frequency suggested by power
analysis. Sampling locations should be selected based on the ability of a small number of
samples to adequately describe water quality at the site and should target areas of beaches in
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closer proximity to fecal pollution sources (portions of the beach with significantly different
mixing should be sampled separately). In addition, collection of samples in the morning appears
to offer the best balance between practicality and generation of data that are conservative
estimators of human health effects. It also provides the best correlation between culture-based
and qPCR results.
2.2.5. Quantification of Pathogens and Sources of Microbial Indicators for QMRA in
Recreational Waters (WERF 201 Oa)
The overall objectives of this study are (1) to identify and address data gaps pertaining to
loadings and concentrations of waterborne pathogens and indicators in discharges to recreational
waters that are affected by fecal pollution; and (2) to compile, analyze and synthesize the data in
QMRA models and waterborne risk management frameworks. These objectives are related to the
comparison of inland and coastal waters because of the following:
1. Pathogen densities typical of specific fecal pollutions sources are characterized. These
data can be used to compare the relative risks posed by inland and coastal sites if it is
found that inland and coastal sites are impacted predominantly by different fecal
pollution sources.
2. The study develops a method by which the relative contributions of different fecal
pollution sources can be determined for a particular site. Knowing the contribution of the
sources will allow improved risk estimates for both inland and coastal sites and will
provide information regarding the how the dynamics of indicators and pathogens differ
for inland and coastal sites. At present, the general features of indicator and pathogen
dynamics are known for inland and coastal sites, but quantitative data for relating
different processes affecting risk are not available.
3. QMRA models for recreational exposure are becoming increasingly available. New
methodologies and data for use in QMRA are provided in this study. Although the new
data and methodologies will be useful if QMRA is used for comparing the relative risks
of inland and coastal sites, because the QMRA model developed in this study does not
consider the characteristics of the waters receiving fecal pollution, the results do not
directly address differences in indicator performance for inland and coastal sites.
Elements of this study were: data collection on pathogen and indicator occurrence and
abundance in diverse fecal pollution sources (literature survey and field study); development and
characterization of the performance of microbial methods for all of the relevant pathogens and
indicators; development of a quantitative microbial source tracking (MST) procedure for
estimating the contributions of various sources to the density of indicators at a specific site; and
QMRA and modeling to relate fecal pollution sources to health risks. In a generic sense, all of
these activities are pertinent to comparison of indicator performance in inland and coastal sites.
The activities with the most direct relevance to differences between these settings are the
quantification of pathogens and indicator prevalence and abundance in specific fecal pollution
sources, and the development of source-specific QMRA models. Each of these areas is reviewed
below, with findings most closely related to differences in inland and coastal waters highlighted.
Data collection
Literature searches and field studies were used to quantify the prevalence and abundance of
several waterborne pathogens (e.g., Salmonella, Campylobacter, Cryptosporidium, Giardia,
adenoviruses, enteroviruses, noroviruses, and rotaviruses) and indicator organisms (e.g.,
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Inland Waters Summary Report November 2010
Bacteroidales, Enter ococcus., and E. coll) in treated and untreated sewage, urban runoff, runoff
from undeveloped sites, livestock feces, wildlife feces, and companion animal feces.
Field studies involved sampling wastewater treatment plant, CSO, and stormwater effluents prior
to mixing with receiving waters. Because the drainages contributing to the discharges are well-
characterized, they might allow generalization of the findings to other drainages with similar
characteristics. Sampling was conducted during (precipitation) event and non-event conditions.
Both culture- and molecular-based methods were used to enumerate pathogens and indicators (to
the extent that both methods are possible for a given microorganism). Novel or particularly
relevant findings from the field studies include the following:
Cryptosporidium density in runoff from forested land was much higher than that in runoff
from lands with other uses;
Salmonella occurred far more frequently in all fecal pollution sources than the other
bacterial pathogens; and
the dominant viruses differed by fecal pollution source, with enterovirus and norovirus
most prevalent in runoff from residential and commercial/light industrial drainages,
rotavirus more plentiful in discharges from agricultural operations, and different
adenovirus types occurring with different prevalences among the fecal pollution sources.
The occurrence of some pathogens was found to be correlated with other pathogens. This finding
might be significant in assessing risk related specific settings, because risks due to multiple
pathogens are additive.
Spiking experiments were conducted such that filtration efficiencies, detection limits, and the
effect of hold times could be established for the bacterial and protozoan organisms chosen for the
study. From those experiments, the authors determined that using holding media stabilized
bacterial populations without adversely effecting protozoa. The authors also noted that from raw
data that, in some cases, recoveries above 100 percent were realized, and in many cases there
were declines in recovery during the 72-hour hold times. The results of the spiking studies do not
contribute directly to the comparison of inland and coastal waters. However, they do provide
information with which pathogen abundance might be characterized in QMRA studies. Correctly
characterizing pathogen densities is very important given the low densities at which pathogens
normally occur and at which some pathogens can initiate infection and illness in humans.
QMRA
A QMRA model was developed for each fecal pollution source. The model incorporated data on
the prevalence and abundance of all the priority pathogens in each fecal pollution source and
used two exposure scenariosdirect exposure to effluent/runoff and exposure to diluted
effluent/runoff As noted above, it is difficult to relate the QMR results directly to differences
between inland and coastal sites because there are no quantitative data describing and comparing
the distribution of fecal pollution sources among coastal and inland waters.
In general, viruses were consistently found to be the risk drivers for all sources, with norovirus
producing the dominant health risk, even for agricultural runoff. The authors do not comment on
the degree to which animal noroviruses are host-adapted and their potential to be infectious to
exposed persons. It was also found that dilution (as simulated in the QMRA) was not associated
with significant risk reduction. This finding is significant, in that one significant difference
between inland and coastal suggested by participants in the WERF experts workshop (Dorevitch
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Inland Waters Summary Report November 2010
et al. 2010; WERF 2009) was the much higher dilution of fecal pollution in coastal waters as
compared with inland waters.
The authors discuss methods by which QMRA might be used for generating new recreational
water criteria or in implementation of those criteria. An important precursor to such uses is
calibration of the models based on findings of epidemiology studies and development of models
with specific components that reflect site characteristics ascertained through sanitary surveys or
other data collection. Underlying the discussion of QMRA is the need to formulate the model
for consistency with the pathogens and exposure scenarios for sites, whether they are inland or
coastal.
Quantitative MST
Along with QMRA model development, the authors developed a quantitative MST methodology
based on quantification of universal, human, cow, and dog Bacteroidales, and that was capable
of determining the extent to which different fecal pollution sources (human, dog, and cow)
contributed fecal indicators in a fecal pollution sample. Given the assumption that fecal pollution
source is the most important determinant of risk for a given receiving water, this tool, along with
sanitary surveys, has the potential to allow comparison of risks between sites (including inland
and coastal sites). The performance of the quantitative MST method was found to be sensitive to
the selection of the different host-specific indicators included in the methodology, and on the
measurement error associated with each of the indicators. Two illustrations of model
performance showed that the model performs well under some circumstances and might be
improved such that it could also perform well when fecal pollution from species other than
humans, dogs, or cows is present.
2.3. Methodology Performance and Relevance to Applicability of Criteria to Inland
Waters (compilation of findings from multiple reports)
This section contains a review of the findings from reports #5, 7, and 8, and peer-reviewed
publications 9 through 13 (Section 1.2.1) that are relevant to the difference in performance of
indicator-method combinations in inland and coastal waters. The emphasis of this section is
method performance and relative differences in qPCR and culture targets, rather than the
association of indicators (as measured by different methods) with health effects. Some of the
factors reviewed in this section are common to both inland and coastal waters. For example,
chlorinated POTW effluent typically has much higher indicator counts via qPCR than culture
methods, regardless of whether the plant is discharging to an inland water or a coastal water.
Other features reviewed herein differentiate inland from coastal waters, such as the degree of
qPCR inhibition exhibited in specific water types.
The section begins with a review of qPCR enumeration of indicator bacteria in environmental
waters and the factors that may impact qPCR performance. Those factors, which include solar
radiation, chlorination, die-off and predation of qPCR and culture targets, and inhibition, may
differ among inland and coastal waters, though the extent to which those factors differ in inland
and coastal settings is yet to be established. The section concludes with a review of several
studies directly comparing culture and qPCR method performance in inland and coastal waters.
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Inland Waters Summary Report November 2010
Factors influencing method performance
Generally, FIB densities derived from qPCR have been consistently reported higher by several
orders of magnitude than those derived from culture-based assays in both coastal and inland
water settings, and under a variety of conditions (e.g., throughout wastewater treatment, at
POTW effluent, different times of day). This is mainly due to the comprehensive or unspecific
nature of DNA amplification in the qPCR assay. All DNA present in a sample is amplified
equally, regardless of the viability status of its host. This total DNA inventory is comprised of
free and dead cell DNA (constituting ambient background DNA), viable but not culturable
bacterial (VBNC) DNA, which is predominant with respect to the last culturable and viable
fraction (corresponding to the cells enumerated by culture-based methods).
In report # 7 (Final report: Comparative Evaluation of Molecular and Culture Methods for Fecal
Indicator Bacteria for use in Inland Recreational Waters (WERF 201 Ob)) the study authors view,
based on the results of their study, is that qPCR methods, as currently optimized, cannot be
applied universally across all inland water bodies. Differences among inland sites (and
presumably among coastal sites as well) that may limit the performance of a particular qPCR
assay are the fecal contamination source, unresolved inhibition, between-lab method variability
(e.g., difference in extraction efficiency or development of calibration curves), and the relative
contribution of DNA from viable v. non-viable cells. All of these factors vary among
waterbodies and laboratories and are not intrinsic to inland waters per se. None-the-less, this
finding implies that method performance can differ from site to site and should be considered
when interpreting indicator levels for a given site or comparing indicator levels among sites.
In a study comparing qPCR and culture counts of Enterococci, Haugland et al. (2005) noted that
geometric mean values of cell equivalents (qPCR counts) for samples taken on a given day were
nearly always one order of magnitude and frequently two orders of magnitude greater than those
for the MF method. Haugland and colleagues suggested that the much higher densities indicated
by the qPCR assays are a result of the inability of the qPCR technique used to distinguish
between DNA from live and dead cells (see the discussion on distinguishing live and dead cells,
below). This finding is significant to the difference in inland and coastal waters in that the
persistence of indicators and relative abundance of live culturable cells and qPCR targets may
differ for inland and coastal sites.
A discrepancy in correlation between qPCR and culture-based results for morning and afternoon
samples was consistently observed for samples taken at Great Lakes beaches during the NEARR
epidemiology studies (USEPA 2010c; report 5 reviewed in this summary). Plots of qPCR counts
of Enterococcus against culture counts of Enterococcus for one of the beaches for data collected
at 8 AM and 3 PM are shown in Figure 3 and 4. Slopes of linear regression models of the log-
transformed densities of the two data sets are significantly different, with the 8 AM samples
exhibiting a slope much closer to 1 than the samples collected at 3 PM. These plots demonstrate
the importance of sunlight inactivation on culture counts and the relative insensitivity of qPCR
targets to solar radiation. In dark conditions culture and qPCR targets have shown different
persistences, with persistence of naked DNA in seawater mesocosms on the order of three times
longer than that of viable culturable enterococci (Walters et al., 2009). The insensitivity of
qPCR targets to solar radiation and the much slower decay of qPCR targets underscore the
necessity to account for ambient background DNA at recreational sites when using molecular-
based monitoring techniques. Culture-based and qPCR results are well correlated at high FIB
densities (viable and culturable fraction predominant). However, this correlation is lost at low
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Inland Waters Summary Report
November 2010
culture-based densities due to high variability of the qPCR in this range and predominance of
VBNC over culturable bacteria and possibility due to the high uncertainty of qPCR assays when
fewer than 100 cells (or qPCR targets) are present (WERF 201 Ob). These findings may be of
significance in the comparison of inland and coastal waters if inland waters are generally more
shaded than coastal waters, if beaches on inland waters tend to be impacted by "fresher" fecal
pollution, or if the microbial ecology of inland and coastal sites are sufficiently different to
impact the persistence of culturable cells and DNA from non-intact cells.
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Figure 3. Paired qPCR and Culture Enterococcus Data: Huntington Beach: 8 AM Samples Only
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Figure 4. Paired qPCR and Culture Enterococcus Data: Huntington Beach: 3 PM Samples Only
Alternative molecular methods or refinements to qPCR may improve the ability of molecular
methods to distinguish between live and dead cells. For example, Bae and Wuertz (2009)
developed a modified qPCR propidium monoazide (PMA) to remove DNA from non-intact cells
from the PCR reaction, resulting in better correlations with culture-based methods. For samples
from the wastewater plant effluent, gene copies from qPCR with PMA were only 30 percent of
those from qPCR without PMA. The difference between qPCR with and without PMA was
greater than two orders of magnitude for samples of wastewater plant effluent. If optimized,
these new techniques have the potential for making the analysis of coastal and inland waters
more consistent.
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Inland Waters Summary Report November 2010
POTW effluent
Strong reductions of cultivable FIB (2-5 orders of magnitude) have been observed throughout
wastewater treatment, especially during secondary treatment and disinfection. Although this
illustrates the ability of such treatments to inhibit cultivability, it does not necessarily
demonstrate that the treatment trains have caused cell death. This is because qPCR counterpart
inventories experience only small reductions or remain unchanged. Such dichotomy between
method outputs is critical both from the standpoint of criteria design but also from the standpoint
of public health, highlighting the potential for a large proportion of VBNC bacteria being
released to recreational waters. In addition, because inland waters generally receive less-dilute
chlorinated POTW effluent than coastal waters, the difference in qPCR and culture densities for
inland waters impacted by POTW effluent could be greater than that for coastal waters.
Some water matrices may have a strong influence on the comparison of qPCR cell equivalents
and MF CPUs. For example, PCR amplification efficiency may be lower in high turbidity
waters than low turbidity waters. He and Jiang (2005) developed a qPCR assay for Enterococcus
and evaluated the assay against MF for unchlorinated primary and secondary POTW effluent,
chlorinated secondary effluent, and marine samples from multiple sites. For unchlorinated
sewage, the difference between qPCR and culture enumerations of Enterococcus varies widely,
with qPCR enumerations exceeding culture enumerations part of the time and below culture
enumerations for other samples. Two plausible explanations for this finding, in addition to
matrix-related effects, are that (1) qPCR results are uncertain and vary significantly between
samples, or (2) qPCR and culture methods measure different features of bacteria and those
features vary differently between samples. In the case of chlorinated secondary effluent,
relatively high enumerations by qPCR potentially indicate the presence of dead cells or extra-
cellular DNA. For samples from a marine environment (Table 4), qPCR results are consistently
higher than those of culture methods.
Impact of Setting (Inland v. Coastal) on the Relative Abundance ofqPCR and Culture Targets
Byappanahalli et al. (2010) found that the relative abundances of enterococci as measured by
cultural methods and qPCR differed for samples taken at beach sites and for samples taken from
a tributary discharging to Lake Michigan in the vicinity of the beaches. The authors found that
the mean of the samples enumerated via cultural methods was not significantly different from
that of the samples enumerated via cultural methods in the tributary. For the two beaches
monitored in the study, the mean of the qPCR counts were 1.6 and 2.1 times the mean CFU
counts and the mean cultural and qPCR counts were significantly different for both beaches. The
authors discount inhibition in the lake water as the cause for significantly higher qPCR counts
than culture counts because samples were analyzed after a 1:5 dilution employed to prevent
inhibition. Further, the authors report that the qPCR Enterococcus counts in the tributary and the
lake water were not significantly greater than those on the beach. These findings support slower
removal of qPCR targets than culturable indicator bacteria as discharge from the tributary is
advected to the beaches or other loading of qPCR targets to the beach sites from sources other
than the tributary.
Telech et al. (2009) developed a series of regression models using several rapidly-measured
environmental variables (e.g., rainfall, turbidity, number of bathers, wind speed and direction)
for predicting qPCR and culturable (membrane filtration) Enterococcus counts at four Great
Lakes beaches. Although the explanatory variables differed by beach for regression models
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Inland Waters Summary Report November 2010
using either type of analytical detection method (i.e., qPCR or membrane filtration), the variables
exhibiting the strongest relationship with Enterococcus densities in the models were consistent
within the analytical detection method. The authors noted that meteorological, physical, water,
and beach characteristics explained more variability in FIB densities measured by membrane
filtration than by qPCR.
Lavender and Kinzelman (2009) developed an empirical model for correcting qPCR
Enterococcus and E. coll densities (as CE) and improving their correlation with culture counts.
Although empirical, their methodology relies upon a condition-specific correction and as such is
related to the theoretical model described above. The study entailed collection of samples at
several locations and analysis of the samples for Enterococcus and E. coll via membrane
filtration and qPCR. Analysis of data found discordance between qPCR and culture data during
rain events or when wave height was above a certain threshold. The authors attributed poor
correlation under those conditions to increased densities of background DNA (not associated
with viable culturable cells). To improve correlation between culture and qPCR densities, the
authors proposed use of a correction factor for conditions associated with high background DNA
densities. In the resulting model, if specific rainfall and wave heights are observed, the qPCR
indicator density is reduced by a correction factor associated with those conditions and estimated
from the data. The correction factors proposed by the authors were different for different sites.
It is likely that correction factors and the conditions under which they are applied would be
substantially different for inland and coastal waters.
Finally, report # 7 (Final report: Comparative Evaluation of Molecular and Culture Methods for
Fecal Indicator Bacteria for use in Inland Recreational Waters (WERF 201 Ob)) reviewed for this
study reports stronger associations of culture indicator density with qPCR indicator density of
Great Lakes waters than for an effluent dominated river or an inland lake. This finding was
based on logistic regression modeling performed on paired culture and qPCR analyses from
Great Lakes waters, rivers, inland lakes, effluent dominated waters, and waters not dominated by
POTW effluents. The authors of that study also noted that for the 3 qPCR methods used, low
levels of qPCR targets were hard to analyze for cell numbers below 100 cells. This shortcoming
of qPCR may influence the correlation between culture and qPCR cell densities if consistently
low indicator densities are typical of an inland or a coastal site.
Summarizing, correlations between qPCR and culture counts differ among all sites, with distinct
differences observed among inland and coastal sites when the two site types were compared
directly. These differences may not be the result of intrinsic differences in inland and coastal
sites but rather the result of site-specific differences in water quality or source characteristics for
the sites studied.
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Inland Waters Summary Report November 2010
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