1. 1
Prioritizing Stormwater Enforcement Efforts, a
Multi-Watershed Study (Project No. 98-04/104)
Final Report
Tom Mahin, MADEP; Dave Gray, EPA Region 1; Ron Stoner, MADEP;
Susan Gifford, MADEP; Oscar Pancorbo, MADEP
* A*
Executive Summary
This project was a collaborative project between four watershed associations and the
Massachusetts Department of Environmental Protection (MADEP). A total of 131
samples were collected during 4 storm events at 18 locations in 4 Massachusetts
watersheds (Merrimack, Charles, Neponset and Ipswich basins.
In addition, the Grantee (MADEP) conducted a comprehensive review of
epidemiological studies completed since EPA’s 1986 recommendations relative to
receiving water bacterial indicators.
This project was proposed to assist in answering the following questions:
 What are “average” levels of bacterial indicators and viral indicators (coliphages)
associated with discharges from municipal storm drains in Massachusetts?
 How do levels of enterococci compare to levels of E. coli in stormwater in
Massachusetts?
 Does land use have a demonstrable impact on levels of bacterial indicators or
viral indicators (coliphages)?
 Do coliphages correlate with traditional bacterial indicators? It can be argued that
the value of coliphages as pathogen indicators is that they may not correlate with
bacterial indicators, which are known to have limitations.
 Are the results from the epidemiological studies conducted since EPA’s 1986
receiving water bacterial standard recommendations consistent with the
recommendations that the states use enterococci for marine waters and either
E. coli or enterococci for freshwaters?
Analysis of the laboratory results led to the following conclusions:
 Enterococci counts were much higher than E. coli levels. Rivers, ponds, lakes,
etc. heavily impacted by stormwater in the watersheds studied may be more likely
to be associated with a water quality standard violations depending on whether
samples are analyzed for E. coli or enterococci.
 Bacterial indicators (E. coli, fecal coliform, enterococci) did correlate with each
other

2. 2
 The viral pathogen indicator used (male-specific coliphages) did not correlate
with the three bacterial indicators or with the water chemistry parameters.
 Significantly higher levels of coliphages were found in certain locations (see
Appendices B and C) raising the question whether very high levels of coliphages
may be indicative of illicit sewage connections?
 Bacterial indicator densities did not correlate with land use.
 In addition, the review of epidemiological studies found that the results generally
were consistent with using enterococci for marine waters and either E. coli or
enterococci for fresh waters.

3. 3
Table of Contents
Executive Summary Page 1
Introduction Page 5
Field Methods Page 6
Laboratory Analyses Page 8
Use of Coliphages as an Alternative Pathogen Indicator Page 10
Results/Conclusions Page 12
References Page 23
Appendix A – Conference Paper Generated by Grant Page 25
Appendix B – Project Quality Assurance Program Plan (QAPP)

4. 4
Disclaimer/Acknowledgements
The project has been financed partially funded with federal Funds from the
Environmental Protection Agency (EPA) to the Massachusetts Department of
Environmental Protection (the Department) under Section 104(b)(3) of the Clean Water
Act. The contents do not necessarily reflect the views and policies of EPA or of the
MADEP, nor does the mention of trade names or commercial products constitute
endorsement or recommendation for use.
The MADEP thanks the following organizations and their staff for their support and
assistance during the project:
The Charles River Watershed Association
The Merrimack River Watershed Council
The Ipswich River Watershed Association
The Neponset River Watershed Association
In addition, thanks to Gary Gonyea for reviewing and commenting on the draft of the
Final Project Report.
Contact for Questions
For questions relative to this study, please contact the Project Officer for the study,
Tom Mahin of MADEP at thomas.mahin@state.ma.us

5. 5
INTRODUCTION
This project was a collaborative project between 4 watershed advocacy groups and the
MADEP Northeast Regional Office and Wall Experiment Station. Stormwater samples
were collected during 4 storm events at 18 locations in freshwater portions of 4
northeastern Massachusetts watersheds: the Merrimack, Charles, Neponset and Ipswich.
The objective of the study was to compare a variety of pathogen indicators for their
potential in prioritizing stormwater remediation efforts. The project was funded by an
EPA 104(b)(3) grant (Project No. 98-04/104) with a state match of a portion of the funds.
Stormwater pollution has been identified as the leading cause of “pathogen” (bacterial
indicator) water quality standards violations in many watersheds. For example, there has
been a considerable amount of work done in the Lower Charles Basin to assess pollutant
loads and characterize water quality conditions. MWRA in its recently issued CSO
Facilities Plan has identified stormwater pollution to be the most prominent pollution
source in the Lower Charles Basin. This conclusion appears to be supported by the water
quality sampling done to date in the basin.
This project was proposed to assist in answering the following questions:
 What are “average” densities of bacterial indicator and viral indicator (coliphages)
organisms associated with discharges from municipal separate storm drains in
Massachusetts?
 How do fecal coliform, enterococci, and E. Coli observed in stormwater and
select instream locations compare in terms of densities?
 Does land use have a demonstrable impact on observed densities of bacterial or
viral indicators (coliphages)?
 Do coliphages correlate with traditional bacterial indicators? It can be argued that
the value of coliphages as pathogen indicators is that they may not correlate with
bacterial indicators, which are known to have limitations.
Field Methods
Sampling Locations & Methodology
All samples were collected, preserved and transported to MADEP’s Wall Experiment
Station in accordance with the project’s approved Quality Assurance Project Plan
(QAPP) dated November 1999 (attached as Appendix E). 117 aqueous samples were
collected from a total of 15 mainstem and tributary stormwater outfalls, plus three
culverted brook locations from Fall 1999 – Summer 2000 (including Winter). Sampling
locations are shown in Figure 1 and described in Appendix A. Outfalls ranged in size
from 8-inch diameter to 7’ x 12’ box culverts, servicing a variety of land uses, both with
and without the contribution of suspected illicit discharges.

6. 6
Quantitative precipitation predictions from the National Weather Service were used with
local commercial weather forecasting outlets to determine if a qualified precipitation
event was forthcoming. For the purposes of this study, a qualified rainfall event was
defined as a minimum 0.25-inch rainfall that generated sufficient stormwater volume and
duration to facilitate collection of all required samples at all stations. Qualified events
included those large enough in extent to have generated the minimum rainfall required
throughout all four watersheds (e.g. a frontal storm) and isolated precipitation events in
only some of the river basins.
Samples were collected after varied antecedent dry period conditions (1 to 10 days),
cumulative rainfall depths (<0.1 to 1.39-inches), and rainfall/runoff duration (first flush to
24-hours after start of precipitation). Though most were single grab samples, 15-minute
grab samples were collected at one station in each watershed during each sampling event
in an attempt to assess any temporal variability. In general, sample volume was collected
directly into 10-liter carboys equipped with a dispensing spigot. Where direct collection
was not possible due to flow angles or access, flow volume was collected and transferred
into carboys from sanitized 2-gallon buckets or from 1-liter sample bottles using a swing
sampler on a telescoping pole. Once full, the carboys were continuously agitated and
individual sample bottles were filled from the dispensing spigot.
Physical Observations & Field Measurements
In addition to collecting aqueous samples for laboratory analysis of physical, chemical,
and pathogen indicators, sampling crews collected field measurements of pH and
temperature, and noted physical observations regarding odor, color, clarity, floatables,
deposits/stains, and vegetation on standard forms, in field notebooks, and through
photography.

7. 7
Figure 1 - Sampling Locations

8. 8
Laboratory Analysis
Summary of Parameters Evaluated as Part of This Study:
 Bacterial Indicators – Enterococcus, E. coli, Fecal Coliform & Clostridium
Perfringens
 Viral Indicators – Male-Specific Coliphages & Somatic Coliphages
 Water Chemistry – Ammonia, Biochemical Oxygen Demand (BOD), Total
Suspended Solids (TSS), Anionic Surfactants (as MBAS) and Fluorescent
Whitening Agents, Fluoride, Specific Conductance, pH, Temperature, Chronic
Toxicity
 Flow Related – Storm Duration, Precipitation, Storm Intensity, Antecedent Dry
Period
 Land Use
Analytical Methods - Physicochemical Analyses
 BOD by SM 5210B
 TSS by SM 2540D
 Ammonia-N by EPA 350.1 (Automated phenate colorimetry)
 Fluoride by EPA 300.0 (Ion chromatography)
 Anionic surfactants as MBAS by SM 5540C
 Specific conductance by SM 2510B
 Fluorescent whitening agents by HPLC (Fluorescence Detector)
Analytical Methods - Pathogen Indicators and Toxicity
Total Coliform SM9222B1
Fecal Coliform SM9222D1
E. coli SM9213D1
Enterococci SM9230C1
C. perfringens EPA-ICR membrane filtration
method3
Male-specific coliphage Double-layer agar plaque
assay3,4,5
Chronic Microtox
Toxicity Test Azur Environmental6
1
American Public Health Association. 1995. Standard Methods for the Examination of Water and
Wastewater, 19
th
edition. APHA, Washington, D.C..
2
U.S. Environmental Protection Agency. 1983. Methods for the Chemical Analysis of Water and Wastes.
EPA600/4-79-020. USEPA, Cincinnati, Ohio.
3
U.S. Environmental Protection Agency. 1996. ICR Microbial Laboratory Manual. EPA/600/R-95/178.
USEPA, Washington, D.C.
4
Grabow, W.O.K. and P. Coubrough. 1986. Practical direct plaque assay for coliphages in 100-mL
samples of drinking water. Applied and Environmental Microbiology. 52(3): 430-433.

9. 9
5
Sobsey, M.D., K.J. Schwab, and T.R. Handzel. 1990. A simple membrane filter method to concentrate and evaluate
male-specific RNA coliphages. J. Am. Water Works Assoc. 82(9): 52-59.
6
Azur Environmental. 1996. Microtox
Chronic Toxicity Test. Azur Environmental, Carlsbad, CA.
Coliphage Analyses at Wall Experiment Station as Part of This Grant
Coliphages were concentrated from 1-L storm water samples by membrane filtration-
elution and assayed by the DAL method as follows:
 Somatic coliphages – assayed on E. coli C or CN-13 host with phage fx174 as
positive control
 Male-specific (F+) coliphages – assayed on E. coli Famp as host with phage
MS2 as positive control.
Coliphage Analysis at Wall Experiment Station

10. 10
Use of Coliphages as an Alternative Pathogen Indicator
Background on Coliphages
 Coliphages are viruses that infect E. coli coliform bacteria and are
nonpathogenic to humans.
 They are believed to be more similar to enteric viruses with respect to physical
characteristics, persistence in the environment and resistance to treatment
processes than are traditional indicator bacteria such as fecal coliforms.
 They are relatively easy and inexpensive to analyze.
 Coliphages have been reported to occur in high concentrations in sewage
treatment plant influent and reproduce in sanitary sewers under appropriate
conditions.
A variety of domestic and un-domesticated animals shed coliphages in their feces, but
usually at lower levels than found in human sewage (Calci et al, 1998).
A study was conducted during the summers of 2002 and 2003 in Madison, Wisconsin
(EMPACT, 2004) during which a total of 223 water samples were collected at the three
beach sites for determination of male-specific coliphages. Male-specific coliphages
were detected in 33 of these samples ranging in relatively low concentrations from <1 to
23 PFU/100mL.
A study conducted by the USGS during 2000 and 2002 (Bushon and Koltun, 2003),
found that coliphages didn’t correlate well with other microorganisms in Cuyahoga River
water and samples from a tributary wastewater treatment facility in Ohio (see table
below).
Source - (Bushon and Koltun, 2003)

11. 11
Investigations conducted by the Massachusetts Water Resources Authority from 1995-
2003 (Ballester et.al., 2004) documented no or poor correlation between coliphages
(male-specific and somatic) and other bacteria indicator organisms (fecal coliform,
enterococci, and E. Coli.) found in Boston Harbor, the Charles River, and the influent and
effluent of the Cottage Farm CSO facility and the Deer Island Treatment Plant.
Investigators concluded that coliphages could be used as relatively conservative tracers of
sewage in the region since they were observed to be more persistent through wastewater
treatment and in the environment than were the bacterial indicators examined.

12. 12
Results/Conclusions
Discussion of Results From This Study
For the traditional bacterial indicators, the highest concentrations were associated with
the summer and fall seasons. It should be noted though that actual loadings to
waterbodies are a factor of flow and concentrations, so overall loadings in the spring may
exceed loadings in the summer (on an overall season basis). The USGS Oregon study
(USGS Oregon, 2002) only looked at one bacterial indicator but found higher E. coli
levels in the summer than in the other 2 seasons studied (spring and winter).
Seasonal Comparison of Concentrations of Select Pathogen Indicators in This Study
Pathogen Indicator
(Geomeans)
Spring Summer Fall Winter
Bacterial Indicators
Enterococcus
(cfu/100 mL)
2,736 14,035 16,204 1,625
E. coli (cfu/100 mL) 350 1,906 1,584 312
Fecal Coliform
(cfu/100mL)
871 5,705 3,999 1,061
Viral Indicator
Male-Specific
Coliphages (pfu/L)
48 137 63 207
Because the summer season is most closely associated with recreational water uses that
are the basis of receiving water standards, a comparison of indicator levels by watershed
during summer storm events was conducted (see table below).
Comparison of Bacterial Indicator Levels by Watershed for Summer Storm Events
Pathogen Indicator
(Geomeans)
Merrimack
Basin
Charles Neponset Ipswich
Enterococci
(cfu/100 mL)
16,686 13,944 8,124 18,537
E. coli (cfu/100 mL) 4,778 NA 3,539 767
Fecal Coliform
(cfu/100mL) 13,897 1,999 5,090 2,882
Comparison of The Results From This Study With Other Stormwater Studies

13. 13
A number of studies have been done relative to bacterial levels in stormwater. The
Oregon USGS study noted below (USGS Oregon, 2002) looked at E. coli levels near
Portland, Oregon and the Charles River USGS Study (USGS Charles River, 2002) looked
at enterococci and fecal coliform levels. Neither of these two studies however looked at
both E. coli and enterococci levels.
The USGS conducted a study of E. coli levels from stormwater runoff in a creek
classified as 100% urban near Portland Oregon. The figure shows the E. coli levels for 3
storms during 1998-1999 (median values are the horizontal line on the box whiskers).
________________________________________________________________________
E. Coli Levels From Storm Runoff in an Urban Creek in Oregon (Source - USGS Oregon,
2002)

14. 14
The USGS conducted a study of the Charles River that included analyzing for fecal
coliform and enterococci but not E. coli in stormwater (USGS Charles River, 2002). As
part of the USGS Charles River Study they determined the “mean” enterococci
concentration from a number of different stormwater studies. These “other studies”
include stormwater data collected from 23 cities between 1978 and 2000 by many
different municipalities and agencies and. The “mean” value of 6,400 CFU/100 mL of
enterococci from mixed land use in the table below (the mean of the enterococci
concentrations from the selected other studies) is similar to the geometric mean (6,700
CFU/100 mL) and median (6,950 CFU/100 mL) of all samples analyzed for this study
(see page 17 of this report).
Summary of stormwater data from other studies (Source: USGS Charles River, 2002))

15. 15
In addition, the USGS Charles River study evaluated enterococci levels at a number of
locations in the Charles River basin, the results of which are shown below: The median
enterococci concentration for the wet weather samples analyzed as part of the Charles
River Study was 13,000 CFU/100 mL (Page 111 USGS Charles River Study, 2002).
Enterococci levels detected as part of the USGS Charles River study (Source - USGS
Charles River, 2002)

16. 16
Conclusion 1: The three bacterial indicators did correlate with each
other (see parameters in bold yellow/underlined in table below).
Pearson Correlation Coefficients
(P < 0.05) for Microbial Parameters in MA
Storm Water
0.460.610.59Som-phage
0.410.480.45MS-phage
C. perfringens
1.000.760.77Enterococci
0.761.000.87E. coli
0.770.871.00
Fecal
Coliform
EnterococciE. coliFecal Coliform

17. 17
Conclusion 2: Enterococci counts were much higher than E. coli counts
in the same sample especially at lower E. coli densities

18. 18
Conclusion 3: The viral indicator male-specific coliphages
(“MS-phage”) did not correlate well with bacterial indicators. This
finding is not surprising given that the potential advantage of a viral indicator is that it
potentially more closely mimics characteristics of actual pathogens (higher survivability
in the environment, etc.) than do bacterial indicators. Therefore it does NOT mean that
male-specific coliphages are not a good pathogen indicator. It was beyond the scope of
this project to sample and analyze for a variety of waterborne pathogens. Such a
comparison of the correlation of coliphages with actual pathogens versus the correlation
of bacterial indicators versus actual pathogens in stormwater would be a worthwhile
future project.
Pearson Correlation Coefficients
(P < 0.05) for Microbial Parameters in MA
Storm Water
0.460.610.59Som-phage
0.410.480.45MS-phage
C. perfringens
1.000.760.77Enterococci
0.761.000.87E. coli
0.770.871.00
Fecal
Coliform
EnterococciE. coliFecal Coliform
Correlation Coefficients for Coliphages (“MS-phage/Som-phage”) with Bacterial
Indicators
Regrsn. of E. coli vs. Male-Specific Coliphages in Storm Water
Correlation: r = 0.48 p < 0.05
E. coli Conc. (Log10
CFU/100 mL)
F
+
ColiphageConc.(Log10PFU/L)
0
1
2
3
4
5
6
0 1 2 3 4 5
Regression line with
95% confidence limits
Theoretical x = y line

19. 19
Conclusion 4: None of the bacterial or viral indicators correlated well
with pH, temperature, specific conductance or BOD.
Pearson Correlation Coefficients
(P < 0.05) for Microbial and Selected
Physicochemical Parameters in MA Storm Water
-0.210.55Som-phage
MS-phage
C. perfringens
0.27-0.300.46-0.19Enterococci
-0.400.39E. Coli
0.19-0.390.35Fecal coliforms
BODSpecific
Cond.
Water
Temp.
pH
Correlation Coefficients for Bacterial Indicators and Coliphages
(“MS-phage/Som-phage”) with pH, Water Temp., Spec. Conductance and BOD

20. 20
Conclusion 5: Significantly higher levels of male-specific coliphages
found in samples from certain locations.
This raises the question of whether very high levels of male-specific coliphages are
indicative of illicit sewage connections in the watersheds studied. As shown in the figure
below, coliphage levels varied from less than 10 PFU/L to greater than 100,000 PFU/L in
this study.
Regrsn. of E. coli vs. Male-Specific Coliphages in StormWater
Correlation: r = 0.48 p < 0.05
E. coli Conc. (Log10
CFU/100 mL)
F
+
ColiphageConc.(Log10PFU/L)
0
1
2
3
4
5
6
0 1 2 3 4 5
Regression line with
95% confidence limits
Theoretical x= yline

21. 21
Conclusion 6: Land use did not significantly impact bacterial levels in
this study (bacterial indicator levels were generally elevated for all types of land use,
see graph below). It was unclear why there was not a correlation with land use. One
possible explanation is that sewage cross connections/illicit connections to storm drains
contributed to pathogen indicator levels regardless of land use type. Also animal scat
contributes to bacterial levels in stormwater regardless of predominant land use type. It
is possible that use of composite sampling might have reached a different conclusion
relative to correlation with land use.
FC
Outliers
E_COLI
Outliers
ENTCOCCI
Outliers
CP
Outliers
MS_PHAGE
Outliers
Extremes
SOM_PHAG
Outliers
Microbial Densities in MA Storm Water by Land Use
Median; Box: 25%, 75%; Whisker: Non-Outlier Min, Non-Outlier Max
LAND USE
Log10Bacterial(CFU/100mL)orColiphage(PFU/L)Conc.
0
1
2
3
4
5
6
Residential
Ind-Comm Mix
Open Space-Rec
Res-Comm Mix

22. 22
Conclusion 7: The study was successful in identifying stormwater
outfalls with particularly high bacterial and viral indicator levels
that should be evaluated further for potential remediation.
Examples of such locations follow (these are not necessarily the most significant
levels detected but rather examples, the reader is referred to Appendix A Sample
Locations and Appendix B Detailed Study Results for more detailed information):
Sample
Location
Site
#
Fecal
Coliform
(cfu/100 mL)
Enterococci
(cfu/100 mL)
E. coli
(cfu/100
mL)
Male-
Specific
Coliphages
(pfu/L)
Somatic
Coliphages
(pfu/L)
Charles
CRWA-
1-3-1
3 53,000 96,000 NA 660,000 56,000
CRWA-
1-4-1
4 50,000 86,000 NA 660,000 14,000
Merri-
mack
MRWC
2-1-1 1 280,000 1,000,000 110,000 1,700 1,700
MRWC
1-3-1 3 55,000 75,000 20,000 120,000 5,600
MRWC
4-3-1 3 26,000 72,000 8,000 200,000 9,600
MRWC
2-3-1 3 260,000 500,000 60,000 42,000 14,000
MRWC
1-4-1 4 91,000 23,000 20,000 180,000 6,800
Neponset
NepRW
A-
1-5-1 5 20,000 5,000 20,000 100 43,000
NepRW
A-
1-5-2 5 31,000 41,000 22,000 210 57,000
Ipswich
IRWA-
2-1-1 1 31,000 20,000 15,000 8 11,000
IRWA-
1-2-1 2 660 330,000 NA 8 65,000

23. 23
REFERENCES
(Ballester et.al., 2004) Ballester, N.A., Rex, A.C., and Coughlin, K.A. 2004. Study of
anthropogenic viruses in Boston Harbor, Charles River, Cottage Farm CSO Treatment Facility
and Deer Island Treatment Plant: 1995-2003. Boston: Massachusetts Water Resources Authority.
Report Enquad 2004-15.57 pp., at URL http://www.mwra.state.ma.us/harbor/enquad/pdf/2004-
15.pdf
(Bushon and Koltun, 2003) “Microbiological Water Quality in Relation to Water-
Contact Recreation, Cuyahoga River, Cuyahoga Valley National Park, Ohio, 2000 and
2002” Rebecca N. Bushon and G.F. Koltun USGS WRIR 03-4333
(Calci et al, 1998) “Occurrence of Male-Specific Bacteriophage in Feral and Domestic
Animal Wastes, Human Feces, and Human-Associated Wastewaters” Kevin R. Calci,
William Burkhardt III, William D. Watkins, and Scott R. Rippey, Applied and
Environmental Microbiology, December 1998, p. 5027-5029, Vol. 64, No. 12
(Cole et al, 2003) “Evaluation of F+ RNA and DNA Coliphages as Source-Specific
Indicators of Fecal Contamination in Surface Waters” Dana Cole, Sharon C. Long, and
Mark D. Sobsey, Appl Environ Microbiol. 2003 November; 69(11): 6507–6514.
(EPA, 1986) Ambient Water Quality Criteria for Bacteria – 1986, EPA440/5-84-002,
January 1986
(Gray and Mahin, 1999) Proceedings of EPA’s BEACH Conferences, Tampa, Florida
and San Diego, CA
(Metcalf & Eddy, 1979) Wastewater Engineering: Treatment Disposal Reuse, table 3-16
Page 103, Published by McGraw-Hill Company 1979
(USGS Oregon, 2002) Phosphorus and E. coli and Their Relation to Selected
Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1989-99, USGS
Water Resources Investigations Report 02-4232
(USGS Charles River, 2002) Streamflow, Water Qualirt, and Contaminant Loadings in
the Lower Charles River Watershed Massachusetts, 1999-2000
Water-Resources Investigations Report 02-4137 02-4137

24. 24
APPENDIX A
Conference Paper Generated
by This Grant

25. 25
Bacterial Indicators and Epidemiological Studies at Beaches;
Implications for Stormwater Management
(WEFTEC 2001 proceedings)
Tom Mahin, Chief of Municipal Services Section
Massachusetts Department of Environmental Protection, Northeast Regional Office
205a Lowell St., Wilmington, MA 01887
Phone: (978) 661-7696, Fax: (978) 661-7615
e-mail: thomas.mahin@state.ma.us
Introduction
Based on epidemiological studies at beaches in the U.S., the USEPA has recommended
for a number of years that states use enterococci as the bacterial indicator for marine
waters and either enterococci or E. coli as the indicator for freshwaters (USEPA 1986).
The Massachusetts Department of Environmental Protection (DEP) recently completed a
comprehensive review and critical analysis of all the more recent (mostly non-EPA)
published epidemiological studies that were conducted subsequent to EPA’s original
recommendation. The goals of the review were as follows:
(1) To evaluate the more recent epidemiological studies to determine whether they
justified changing the DEP water quality standards for fresh and marine waters
(currently fecal coliform for both types of waters), and
(2) To analyze the potential implications for stormwater management given that
stormwater discharges are the main cause of exceedances of bacterial water quality
standards in Massachusetts.
Both the conclusions and the methodologies used in the studies were reviewed in detail.
Examples of some of the major epidemiological studies reviewed are noted below.

26. 26
Examples of Relevant Epidemiological Studies
 During 1989-1992 during four consecutive summers, epidemiological studies were
carried out at marine beaches in England , the “UK beach studies” (Kay et al. 1994).
The UK beach studies differed from previous epidemiological studies in two
important ways. First, volunteers were randomly assigned as either bathers or non-
bathers. Secondly rather than relying of self-describing of symptoms, clinical
examinations were included as part of the study. The studies involved a total of 1216
participants. The studies found a dose-response relationship between fecal
streptococci (FS) and gastrointestinal (GI) illness. It should be noted that the
definition of fecal streptococci as used in these studies is very similar or the same as
enterococci as used in the U.S. An increase in GI illness rates was observed when FS
levels exceeded 32 colony-forming units (cfu) per 100 ml.
The studies also reported what was described as a “clear dose-response relationship”
between respiratory illness and fecal streptococci levels. The threshold level for
increased illness was 60 cfu/100 ml. While these studies only dealt with marine
waters and not fresh waters, the results appear consistent with the work done by EPA
that indicated that enterococci works well as an indicator of rates of GI illness in
marine waters whereas fecal coliform does not.
 A major epidemiological study was conducted in Hong Kong in 1992 involving
25,000 beach-goers at coastal beaches (Kueh et al. 1995). Unfortunately fecal
streptococci/enterococci was not analyzed for. The study did find that “no direct
relationship between GI symptoms and E. coli or fecal coliforms could be identified
in this study”. The findings of the study appear consistent with USEPA’s position
that fecal coliform and E. coli are not effective at predicting GI illness in users of
marine waters.
 An epidemiological study was conducted in 1995 of swimmers in the marine waters
of Santa Monica Bay (Haile et al. 1996). The study included 111,686 subjects.
Illness rates were compared for those swimming near stormwater outfalls versus
those swimming further away. Illness rates were also compared to various bacterial
indicators. Fecal coliform levels > 400/100 ml correlated only to skin rash and
E .coli correlated only with earache and nasal congestion. Enterococci levels
>106/100 ml were statistically correlated with “highly credible GI illness” and also
with “diarrhea with blood”.
Conclusions and Unresolved Issues
 How much of a risk does wet weather stormwater/urban runoff pose to recreational
beach-goers? The Santa Monica study doesn’t appear to have answered this question
because the samples presumably included either mostly dry weather flow (given the

27. 27
climate in Southern California) or non-local origin flow. The dry weather flow
presumably could include significant amounts of illicit sewage connections. This
could have been responsible for significant percentage of the illness rates detected.
None of the epidemiological studies described above appear to have relied strictly on
traditional wet weather stormwater conditions as occur in non-arid areas of the U.S.
An epidemiological study was conducted by Yale University and EPA staff at a
pond used for swimming in Connecticut that received only runoff contaminated by
animal feces and not sewage (Calderon et al. 1991). The study that included 104
families did not detect a correlation between illness rates and levels of traditional
bacterial indicators but did find that bather density correlated with increased rates of
gastroenteritis in swimmers.
It is unclear what the source of contamination is in many of the studies reviewed.
EPA’s original epidemiological studies may have involved contamination resulting
mostly (or in significant part) from chlorinated effluents.
Since stormwater discharges are mostly unchlorinated, they may exhibit lower
pathogen to bacterial indicator levels than may have been present (but not analyzed
for) in many of the epidemiological studies if chlorinated effluents were the primary
source. Such a lower pathogen to indicator ratio, if confirmed, could have the
potential to overestimate the risk due to stormwater relative to previous EPA
studies.
Given the high levels of enterococci and other bacterial indicators that are
commonly detected in stormwater in urban areas around the country, evaluating the
true risk of stormwater becomes of critical importance. It should be noted however
that many stormwater drainage systems in urban areas (at least associated with the
aging infrastructure in the in the Northeast U.S.) contain significant amounts of
illicit sewage connections. Given this fact, a conservative approach would argue for
adopting the levels recommended by EPA at least until more progress is made in
reducing illicit connects and until future epidemiological studies (if conducted) can
provide better information relative to the specific risk from stormwater.
 Can a single indicator adequately predict a range of illnesses in swimmers in
marine waters? USEPA recommends that only enterococci be used for marine
waters. The UK beach studies found that only increased levels of fecal coliform
organisms were predictive of ear ailments among bathers in the coastal waters studied
(Fleisher et al. 1996). In addition, the Santa Monica study found that E. coli was the
best predictor of earache after swimming (marine waters). Both of these more recent
studies seem to back up the argument that enterococci be used as the overall best
indicator for marine waters at least for gastroenteritis and respiratory illness.
However they also seem to point to the need for additional epidemiological studies to
clarify whether a single indicator is adequate to predict illness in swimmers using
marine beaches.

28. 28
References
Calderon, R. 1991. Health Effects of Swimmers and Nonpoint Sources of Contaminated
Waters. International Journal of Environmental Health Research 1, 21-31
USEPA 1986. Dufour, A., and R. Ballentine Ambient Water Quality Criteria for Bacteria
– 1986. EPA 440/5-84-002
Fleisher, J. M. et al. 1996. Marine waters contaminated with domestic sewage: nonenteric
illness associated with bather exposure in the UK. Am J Public Health 86: 1228-34
Haile, W., et al. 1996. An Epidemiological Study of Possible Adverse Health Effects of
Swimming in Santa Monica Bay. Final Report, May 6, 1996).
Kay, D. et al. 1994. Predicting likelihood of gastroenteritis from sea bathing; results
from randomized exposure. Lancet 344, 905-09
Kueh, C.S. et al, 1995. Epidemiological Study of Swimming-Associated Illnesses
Relating to Bathing-Beach Water Quality, Wat. Sci Tech.

29. 29
Appendix B – Project Quality
Assurance Program Plan (QAPP)
Available upon request at MADEP, please contact Gary Gonyea at
gary.gonyea@state.ma.us