A survey of the microbiological water
quality of coastal and fresh waters in
the Dublin area
Yuliya Shakalisava, Christina Doherty,
Wojciech Hahnel, Dermot Diamond
Marine Institute Beaufort Sensors Initiative1
Adaptive Sensors Group
National Centre for Sensor Research
Dublin City University
May 2010
1
This work was supported under the Marine Institute Beaufort Sensors Initiative. For more
information see www.ncsr.ie/Beaufort/index_home.html
Table of contents
ABSTRACT ........................................................................................................................................... 3
1. INTRODUCTION ............................................................................................................................ 3
2. MATERIALS AND METHODS ..................................................................................................... 7
2.1 WATER SAMPLES ...................................................................................................................................... 7
2.2 COLIFORM ANALYSIS ................................................................................................................................ 7
2.3 PHOSPHATE ANALYSIS.............................................................................................................................. 7
3. RESULTS AND DISCUSSION ....................................................................................................... 8
3.1 URBAN WATER QUALITY .......................................................................................................................... 8
3.2 POINT OF SOURCE CONTAMINATION ....................................................................................................10
3.3 RURAL CONTAMINATION .......................................................................................................................12
3.4 PHOSPHATE AND MICROBIOLOGICAL WATER QUALITY ....................................................................13
3.5 NORTH DUBLIN COASTAL AREA............................................................................................................14
4. CONCLUSIONS .............................................................................................................................................15
5. ACKNOWLEDGMENTS ................................................................................................................................16
APPENDIX I. E. COLI AND TOTAL COLIFORMS (TC) COUNTS IN WATER SAMPLES..17
APPENDIX II. MAPS OF THE INVESTIGATED AREA. ............................................................ 35
APPENDIX III. PHOTOGRAPHS OF THE SITES. ......................................................................43
REFERENCES .....................................................................................................................................50
2
Abstract
The microbiological pollution of water is a serious global environmental issue.
The pollution of water with human and animal waste is a source of hazardous pathogens
and, unfortunately, contamination of natural water bodies poses a serious health risk. The
acceptable microbiological quality of water (inland, coastal and transitional) is directed
by the European Union (EU) and Ireland must be compliant with the good water quality
criteria by 2015. The aims of this study were to
(1)
survey pollution levels in rivers, canals and coastal waters under varying
conditions,
(2)
to identify where possible the causes of the contamination, and
(3)
to compare the findings with the limits as set out in the relevant EU
directive.
A total of over 100 water samples have been analysed for the presence of total
coliforms and E. coli. The sampling locations were selected in the rivers and canals of the
urban Dublin area, in the local rural environment, and along the North Dublin seashore.
The additional analysis of water samples for the content of phosphate was performed for
background information. The results of this study show the presence of high levels of
faecal contamination in the majority of the water samples taken. The Canals of inner
Dublin city area were shown to have the best microbiological water quality. Dangerously
high counts of faecal coliforms were detected at several sampling points in the Irish Sea
coastal area.
1. Introduction
The pollution of water is a serious environmental issue on an international scale.
The aquatic environment has to be protected by legally enforceable quality stantards. In
the European Union, the Water Framework Directive (WFD)1 requires the Member States
to make sure their waters achieve and maintain at least ‘good water quality’ status by
2015. The following EU regulations2 were directed in order to achieve this: Bathing
Water Directive, Drinking Water Directive, Environmental Impact Assessment Directive,
Sewage Sludge Directive, Urban Waste Water Treatment Directive, Nitrate Directive,
Integrated Pollution Prevention Control Directive, etc. Some other basic measures
include cost recovery for water use, measures to promote efficient and sustainable use,
3
protection of drinking water sources, authorisation of discharges to groundwater, control
of point source discharges and diffuse source pollution, prevention or reduction of
accidental pollution, etc.
According to the Irish Environmental Protection Agency (EPA)3 not all Irish
waters sampled meet the good water quality status. Eutrophication is one of the main
threats to the water quality, arising from the discharge of fertilisers, sewage and
detergents. The unsatisfactory microbiological condition of private group water schemes
and groundwater is a major issue for Irish drinking water, with up to 30 times the UK E.
coli level in some cases, according to an EPA report4. Only 40% of estuarine and coastal
areas are classified as unpolluted. Up to 52% of all monitoring locations for ground water
confirmed bacteriological pollution at some stage. The overall prognosis predicts that
‘good water status’1 might not be achieved by 2015 for 64% of rivers, 64% of lakes, 53%
of estuarine waters, 27% of coastal waters and 62% of groundwaters3.
In order to successfully accomplish the measures for improvement of water
quality it is necessary to know the sources of the pollution. Depending on the nature
chemical contamination, it can be easily attributed to the industrial or domestic discharge
from the compositional ‘fingerprint’ obtained from analytical measurements. However, in
the case of microbiological or faecal contamination of water, it is often difficult to pinpoint the origin; expensive and very sophisticated sampling and analysis methods are
required for this. Faecal pollution commonly arises from human or domestic and feral
animal faecal materials. Since many water bodies, such as rivers, would have the access
to both source types (i.e. passing through urban and rural areas), it is a difficult task to
absolutely identify sources and take measures for improvement, and take successful legal
action against those responsible for the pollution. Sewage treatment utilities and animal
processing plants discharge wastewater and have the potential to adversely affect the
bacterial quality of receiving5. Soil and water percolating through soil can also be
contaminated if the effluent is discharged onto the land, and will eventually reach surface
and ground waters6. It has been shown previously7 that grazing livestock cause faecal
bacterial contamination of streams. Through this source, faecal material is delivered both
by overland8 and subsurface9 flows to a waterbody. Direct evidence of faecal material can
be found where animals are in close proximity to a water body10. Niemi and Niemi11
showed that wild animals also have to be taken into consideration when considering
faecal pollution of natural waters.
4
Pathogenic microorganisms can cause a serious health risk even at low levels and
therefore must be controlled for safety and health. Faecal pollution can also degrade the
aquatic environment for shell-fishing or shell-culturing. The pollution of water by human
and animal waste is a primary source of hazardous pathogens. Pathogens may be rare,
difficult to culture and erratic in distribution, and therefore it is common to monitor
specific bacteria that are accepted general indicators of faecal contamination. According
to the guidelines and standards for water quality of World Health Organisation (WHO)12
organisms that indicate the presence of faecal contamination are the thermotolerant
coliforms, collectively known as E. coli. WHO recommends analytical methods for the
bacterial enumeration based on cell growth, such as the most probable number (MPN)
and membrane filtration (MF) methods13. These require at least 24 hours to generate
preliminary data, and 48-72 hours to confirm the results. Delays of this magnitude are
obviously an issue in an emergency situation, in which decisions regarding the
management of the public water supply or bathing areas have to be taken quickly in order
to minimise the public health risk. Unfortunately, delays in decision making can result in
situations such as occurred during the 2007 Cryptosporidium outbreak in Galway
(Ireland), when the bacteria in water supply were detected after 24 hours, by which time
250 people and 900 households had been affected14.
Microbiological standards of water bodies in Ireland are a subject of concern for
the general public and the scientific community as cases of elevated quantities of
indicator bacteria of faecal contamination have been registered in bathing, ground and
drinking water. Over 8% of public water supplies were contaminated with E. coli in
2006-2007 according to an Irish EPA report, and a survey by the Food safety authority of
Ireland recently revealed E. coli in 1% of Irish bottled drinking water. The main reason
for non-compliance of Irish bathing water with the guide limits was elevated faecal and
total coliform counts5.
When considering statistics from such reports it should be
appreciated that, in general, monitoring of water and air quality is done by taking 3 or 4
samples per year at a relatively small number of locations, a reflection of the labour
intensive, and consequently expensive nature of environmental sampling. Given such
low levels of sampling, it is a cause for concern that compliance is not being properly
policed, and there could be many instances of breaches of the regulations going
unnoticed.
Clearly, it is important to study the contamination of water and indentify its
sources in order to take the most efficient corrective actions. Cost and time, required for
5
the sampling of water and culture based methods themselves, obviously do not allow
continuous monitoring of bacteriological quality of water at multiple locations. Thus,
according to the latest EPA water quality report in Ireland, only 3 samples per each
established location per year are being analysed (ground water)15. While monitoring of
this kind is useful in establishing general information about the water quality at these
locations, there are obviously large gaps in our knowledge, as bacterial numbers can vary
significantly within these sampling instances, and outside of the sampling locations.
With the implementation of Directive 2006/7/EC by 201516, the EU is in the midst
of a radical change in the way the microbiological contamination of waterways is
measured, interpreted and classified. The directive includes a change of faecal indicator
bacteria to Intestinal Enterococci and E. coli and an associated adjustment to differing
indicator bacteria levels for inland waters and coastal/transitional waters and water
classification into 3 health risk categories (Table 1).
Important environmental factors such as physical characteristics of a catchment,
land management strategies within it, rainfall, stream flow and recent climatic conditions
affect the impact of each source of faecal pollution17. However, the interaction between
the above factors is not yet understood, and it is difficult therefore to decide specific
actions that will minimise faecal contamination.
Table 1: Health risk classification of bathing water according to EU directive
2006/7/EC16. * Based on 95 – percentile evaluation. ** Based on 90 – percentile
evaluation
Inland Water
Excellent
Good
Sufficient
Intestinal Enterococci
200*
400*
330**
E. coli
500*
1000*
900**
Excellent
Good
Sufficient
Intestinal Enterococci
100*
200*
185**
E. coli
250*
500*
500**
Coastal Transitional Water
The survey summarised in this report was conducted in an attempt to obtain a
better picture of the microbiological water quality in the Dublin area and deepen the
understanding of its correlation with different environmental parameters and sources of
the pollution. For this study, over 100 samples were taken from various locations and
6
water bodies in and around Dublin. Urban, rural and estuarine water samples were
analysed for E coli and total coliform content and the results linked where possible to the
surrounding area in order to understand the possible reasons for the presence of the
pollution.
2. Materials and methods
2.1 Water Samples
Water samples were collected from the rivers Liffey, Dodder and Tolka, Grand
Canal and Royal Canal in Dublin (Ireland) as well as coastal waters in North Co. Dublin
at different times over the period November 2008 - September 2009. Maps showing the
locations of all sampling points are supplied in Appendix II. The samples were collected
into 500 mL sterile plastic bottle, shielded from the exposure to light, cooled with the ice
packs and transported to the laboratory within a maximum of 4 hours, where they were
refrigerated or analysed immediately.
2.2 Coliform analysis
E.coli and total coliforms were analysied using 3 MTM PetrifilmTM, manufactured
by 3M Microbiology, USA, and purchased from Reagecon, Shannon, Ireland. A 1 mL
water sample was added to the Petrifilm and spread evenly over the agar area. Petrifilms
were incubated at 37ºC for 24 h. Blue colonies with entrapped gas were counted as E.
coli and a summary of blue colonies with gas and red colonies associated with gas - as
total coliforms. Each dilution was performed in duplicate, and each experiment
accompanied by a control test. Correlation of petrifilm results with the standard
membrane filtration method has been reported in the literature18,19 and we have used
these protocols to validate our methods through work completed in our laboratory
previously20.
2.3 Phosphate analysis
Phosphate analysis of water samples was performed using an in-house
developed phosphate analyzer, using procedures described elsewhere21,22.
7
3. Results and discussion
3.1 Urban water quality
In the urban Dublin area, samples were taken from the rivers Tolka, Dodder, and
Liffey, and The Royal and Grand Canals and analysed for E. coli and total coliform
counts. The resulting data is presented in Appendix I. Separately, E. coli levels in
samples taken from the river Tolka near Griffith Park were measured on various days
within a year (Figure 1). The average count (Table 2) was above 5000 CFU/100 mL with
samples varying from 350 CFU/100 mL to over 16,000 CFU/ 100 mL. The horizontal
line in Figure 1 represents the 500 CFU/ 100 mL threshold for “excellent” water quality
in terms of E. coli according to the Directive 2006/7/EC for bathing water quality16.
While the river Tolka is not recognised as a location for public bathing, wherein this
threshold applies legally, the levels found were disturbingly high, as Griffith Park is a
popular recreational area and the river Tolka is easily accessible for public at this location
E. coli count CFU/100 mL
(Photo 1 in Appendix III).
12000
E. coli 500 CFU / 100 mL *
8000
4000
10
th
N
11 o v
th '08
12 No v
th '08
N
19 ov
th '0 8
N
24 o v
th '08
N
1s o v'0
tD 8
2n e c'0
d
8
D
e
c
3r
d '08
D
4t ec'0
h
De 8
8t c'0
h
8
De
c'0
7t
8
h
Ju
l
'
09
8t
h
Ju
9t l'09
h
J
22 u l'0
9
st
J
24 ul'0
9
th
J
27 ul'0
9
th
J
29 ul'0
9
th
11 Jul
'
0
th
Au 9
g'
09
0
Date
Figure 1. E. coli concentration in samples of water from river Tolka taken on
different dates at Griffith park. For the exact location see Map 1, Appendix II.
*The line indicated corresponds to “excellent” water quality for E. coli according
to EU Directive 2006/7/EC for bathing water quality.
8
The average E. coli data for sampling locations in Dublin are presented in Table
2. It can be seen that faecal coliforms in the River Liffey were generally in the range
2000 and 6000 CFU/100 mL, depending on the location, with disturbingly excessive
levels recorded (24000 CFU/100 mL) at the Parliament Bridge sampling location. While
it is only possible to compare the obtained microbiological counts to the inland water
quality requirements for bathing water (Table 1), it is noticeable that in general water
samples from the rivers (Liffey, Dodder and Tolka) contain significantly higher levels of
E. coli than Dublin city canal waters. The faecal coliform content of Grand canal
(Kilmainham) and Royal canal (Phibsboro) was on average 20-30 CFU/ 100 mL and was
on all occasions no more than 50 CFU/100 mL. While these urban water bodies are not
generally used for swimming, some social activities, such as the “Liffey swim” take place
in the urban area of the river Liffey, including Parliament Bridge. In addition, numerous
recreational parks are situated along the river Tolka and Dodder, where the water is easily
accessible for children and their parents, pets and their owners.
Table 2. Average E. coli count in the investigated inner city Dublin water bodies.
Sampling locations are on Map 1, Appendix II.
Sampling location
CFU/100 mL
StDev
n
Liffey Tall Bridge
2157
2246
7
Liffey Parliament Bridge
6361
10021
9
Liffey Islandbridge
6467
8746
6
Grand Canal Kilmainham
36
24
7
Royal Canal Phibsboro
14
24
7
5137
4869
18
Tolka Griffith Park
From the detailed data in the Appendix I it can be seen that extremely high
levels of faecal coliforms were detected in rivers after a strong rainfall event. For
example, E. coli levels in the River Liffey in all three sampling locations on August
31st were about 1 order of magnitude higher than on August 27th. Remarkably, the
samples from both canals in Dublin maintained the same low levels of bacteria
regardless the weather conditions, because these water bodies are not subject to the
same ‘washout’ phenomena experienced with rivers. In fact the main water source for
the Grand Canal is a pristine aquifer located in County Kildare23. Usually rain raises
9
the faecal coliform levels in water bodies24 as it washes the contamination from soil
and soil waters in rural areas into rivers and streams.
Dublin Bay is the estuarine area of the Rivers Liffey, Tolka and Dodder, and
the quality of the water in these rivers will contribute to the overall marine water
quality in the bay. The River Liffey was sampled at the three locations within the
estuarine area in Dublin city centre (Map 1, Appendix II). On average, the sample
collected at the location nearest to the sea had significantly lower levels of faecal
coliforms (Table 2), and typically total coliforms and E. coli were found in
significantly less quantities in seawater than in fresh water25. Levels can also vary
significantly throughout an estuary due to dilution of fresh water by seawater through
tidal fluctuations. However, from the results in Appendix I (Data 3- Data 9) on every
sampling day there were different scenarios of bacterial count distribution along the
river. Thus, on some occasions (Data-3 and 7) the E. coli levels at Tall Bridge and
Parliament Bridge on the River Liffey (Map 1, Appendix II) did not vary significantly
and were low in comparison to other days (between 1000 and 1500 CFU/100 mL).
Conversely, on other occasions (Data-4 and 5), the E. coli levels in samples from
Parliament Bridge were nearly 5 times higher than those at Tall Bridge, at 24000
CFU/100 mL. Considering the locations, it was our opinion that this large difference
in pollution is arising from a point source between the sampling locations, but this
was difficult to verify due to the limitations of this study. This was also true for the
River Dodder samples (Data-1 and Data-2, Appendix I).
3.2 Point of source contamination
3.2.1 Tolka pollution
In the period of the early December 2008 the level of faecal contamination of the
River Tolka in the location of Griffith Park was incredibly high, reaching in excess of
10,000 CFU/ 100 mL (Figure 1), which was a cause for concern. A detailed investigation
was therefore initiated to identify the possible pollution source. The river and surrounding
area, the sampling locations are shown on the map in Figure 2.
10
Figure 2. River Tolka (Dublin, Ireland) map and the location of the sampling points.
In an attempt to locate possible sources of the high levels of contamination, a
portion of the river was visually inspected. This led to the discovery of a pipe source that
was discharging raw sewage into the river. Definitive photographic evidence of the direct
sewage pollution arising from this pipe is shown in Photo 2, Appendix III. In order to
confirm the source of the pollution, several samples of water were taken from locations
along the river, upstream and downstream the source (Figure 2). Location 1 is upstream
from the pipe, in the vicinity of the Botanic gardens, whereas location 2 is within several
meters downstream from the pipe. It was thought to be unreasonable to undertake sampling
at the pipe itself for safety reasons, as it was out of reach and the river flow was very high
at that time. Two other locations (3, 4, Figure 2) were selected further downstream from the
pipe. The counts obtained for E. coli and total coliforms are shown in Figure 3. It can be
seen that the number of bacteria sampled within proximity of the pipe and further
downstream were at least twice those obtained upstream from the pipe. It should be noted
that even at the sampling point upstream the values of E. coli and total coliforms were 3550
and 6000 CFU/100 mL, respectively, which is alarmingly high and significantly in excess
the national bathing water guide limits mentioned previously. These results confirm that
this pipe outlet is one of the sources of the seriously high levels of contamination of the
River Tolka, and that additional contamination is happening further upstream from as yet
unidentified sources. It should be noted that these samples were taken after a period of
heavy rainfall had occurred in the area.
11
E. coli
Bacterial count CFU / 100 mL
20000
Total coliforms
15000
10000
5000
0
1
2
3
4
Location
Figure 3. Microbiological count in water according to different sampling locations
on the River Tolka. Locations correspond to the map in Figure 2. Error bars
indicate the maximum and minimum values on duplicate measurements.
3.2.2 Canal water quality
Samples taken from Kilmainham on the Grand Canal suggested excellent
water quality, with very low levels of microbiological contamination. Later, a second
location on the Grand Canal was added to this study in order to investigate the effect
of a floating restaurant located on a barge, on the Grand Canal in the Dublin 6 area
(location 8 in Map 1, Appendix II). The results can be found in Data 6 – Data 9,
Appendix I. The study showed the levels of E. coli varied from being slightly elevated
(100 CFU/ 100 mL) to 700 times greater than the levels measured at the Kilmainham
sampling location. In Data 8 and 9, Appendix I, an even more detailed examination of
the effect of the barge was conducted, with samples being taken within several
hundred meters of each other, directly upstream and downstream of the barge. On one
occasion the faecal coliform count in the water sample downstream of the barge (in
the direction of the flow) was 3550 CFU/100 mL while upstream it was 250 cfu/100
mL. Taking into the account that the rest of Grand Canal and Royal Canal does not
show signs of any significant pollution, this particular dining unit is the most likely
source of the sewage discharge into the Grand Canal.
3.3 Rural contamination
Further sampling locations on the River Tolka were chosen that were further
upstream in Co. Meath, before the river enters the city (Map 2, Appendix II). The
faecal and total coliform counts found at the sampled locations are presented in Data
12
10 and 11, Appendix I. E. coli levels were above 1000 CFU/ 100 mL at all locations
sampled, except for the Lismahon road sample, which was 350 CFU/ 100 mL. The
river was very low at the time of sampling, and in some cases, it wasn’t possible to
collect the required 500 mL of sample. In Co. Meath 70% of economic activity arises
from farming26. At the time of sampling, there was clear evidence of animal faecal
contamination at the river. For example, at the sampling location in Ashtown, grazing
horses were noted within several meters of the river (Photo 2, Appendix III). In Photo
3, Appendix III, footprints from cattle can be seen in the river near Batterstown
(location 10 in map 2, Appendix II). It is also obvious that this particular part of the
river was being used as a regular drinking source by the animals. The E. coli level in
the sample from this location was particularly high compared to samples taken from
other locations on the same day (Data 10, Appendix I).
According to the Map 2 (Appendix II) the River Tolka emerges from several
streams in Co. Meath that combine into one river-body in the vicinity of the
Damastown Industrial Estate. It is also evident from the bacteriological count at all
rural sample locations, that the contamination of the individual streams together
contribute to the relatively high levels of faecal coliforms found downstream in the
direction of Dublin city.
3.4 Phosphate and microbiological water quality
On some occasions during this study, the faecal coliform count was compared
to the phosphate concentration in the same water sample. The results for the rivers in
the urban area of Dublin city are shown in Data 12, Appendix I. Overall, the
concentration of phosphate in the samples varied over a narrow range above 0.1 mg/L
and did not exceed 0.3 mg/L. The faecal coliform numbers in the same samples are in
excess of 1,000 cfu/100 mL (Data 1, Appendix I). The relative number of faecal
coliforms and relative phosphate concentration correlate in 3 out of 4 investigated
samples on this occasion. Only one sample from river Tolka at Griffith park showed
higher phosphate content when the E. coli count was low in comparison to other
samples.
Data 13, Appendix I shows the E. coli and phosphate levels in the samples
taken from the rural part of the river Tolka in Co. Meath. The phosphate concentration
in all samples was above 0.2 mg/L and at Griffith park, and Damastown (Map 2,
Appendix II), they were considerably higher at 0.6 mg/L. At sampling locations 8-11
13
(Map 2, Appendix II) sited at small streams that feed into the Tolka, the phosphate
levels were found to be quite low, below 0.3 mg/L, and at locations further
downstream, higher levels of phosphate were found. As with the faecal coliform data,
the concentration of phosphate in the main river body was found to be generally
higher than in the individual feeder streams. It would therefore appear that
contamination occurs along the main river course. In general, the results of this study
are in accordance with the faecal coliform distribution in the same water samples
(Data 11, Appendix I), supporting the view that contamination in the main tends to
arise from multiple diffuse sources rather than a single point.
3.5 North Dublin coastal area
Microbiological pollution of a coastal area is mainly caused by contributions from
polluted rivers and direct sewage discharge from Waste Water Treatment Plants. This area
is particularly popular with the public for bathing and recreation due to the numerous
beaches. The map of the sampling locations is shown in Map 3, Appendix II. Balbriggan
and Portrane were the main focuses of the sampling expeditions. In the Balbriggan area, the
River Bracken outlets directly into Balbriggan Harbour. Photo 5 in Appendix III shows a
satellite picture of Balbriggan Harbour at high and low tide. It is seen that mixing of water
from the river and the seawater is extensive due to the tidal movements. Photo 6 (Appendix
III) shows the disturbing state of the sewage pipe leading to the river.
Further south towards Dublin, Portrane is the site of a Waste Water Treatment
Works. The outfall of this plant goes directly to the Irish Sea. Maps 4 and 5 (Appendix II)
show the exact location of the treatment plant and the outfall pipe.
The data in Appendix I (Data 14) shows the Total and E. coli counts for the river
Bracken in Balbriggan and Portrane outfall water samples. While the results for later
showed increased 8500 CFU/ 100 mL of E. coli, the most shocking levels of E. coli and
total coliforms were for samples taken from the Bracken river, at over 50,000 CFU/ 100
mL. It should be appreciated that these values are for water samples taken from the river
that goes directly into Balbriggan Harbour and they exceed the criteria for excellent water
quality (Table 1) by over 100 times. Data 15 and 17 (Appendix I) shows the results for
water samples of various locations along the Balbriggan River and harbour. These samples
were taken on different days and although the faecal coliform count wasn’t as high as in
samples from the previous day (Data 14, Appendix I), they are still very elevated at up to
6000 CFU/ 100 mL.
14
The outfall pipe from the Portrane Waste Water Treatment Works was visually
inspected. The Photos 7-9 (Appendix III) represent the frightening conditions of the pipe
delivering the sewage to be discharged in the sea at the beach area (Maps 4, 5, Appendix
II). Large cracks and holes were clearly evident within first 70 m of the 600 m outfall,
corresponding with the region crossing the beach. Data 16 (Appendix I) shows the
extremely high total coliform and E. coli numbers obtained in samples taken from several
pipe cracks; they were above 700,000 and 140,000 CFU/ 100 mL, respectfully. These
levels of faecal coliforms present in sewage that goes directly into the sea adjacent to the
beach area certainly represent serious health risk for those who might be in contact with the
water.
Map 4 (Appendix II) shows the locations of the Portrane and Donabate bathing
water quality monitoring points. It can be seen that these are quite distant on either side of
the Waste Water treatment Works outfall, and samples from these locations would not
necessarily detect the very high contamination due to the damaged outlet pipe, giving the
impression that no pollution exists in the area.
4. Conclusions
This work investigated the faecal contamination of numerous water bodies in
Dublin area, including rivers and canals, spanning the urban and rural environment. The
results showed that the poor quality of the rivers in Dublin city is strongly related to
human activity. Direct sewage contamination of the river Tolka from a sewage pipe
beside the Botanic Gardens was discovered and reported through local media to Dublin
City Council, who investigated the situation, and claim to have rectified matters. The
water quality of the canals in the Dublin area was excellent, except for a point source of
contamination of the Grand Canal, apparently due to a floating restaurant. In rural areas
outside Dublin, the evidence suggests that human sewage contributes to a lesser extent to
the high levels of microbial contamination in the River Tolka compared to farming
activities in the area. The extremely high faecal coliform counts that were registered
coastal waters in North County Dublin appear to arise from point sources associated with
sewage treatment at Balbriggan and Portrane. These are potentially a threat to human
health and action should be taken to remediate and improve the manner in which
discharges are made into local river and coastal waters that are accessible to the public.
15
5. Acknowledgments
Our thanks to Dr. John Cleary for the analysis of phosphate in water samples.
This work was supported by Beaufort Marine Research Award, Marine Institute, Ireland,
the National Centre for Sensor Research, the SFI-funded CSET CLARITY and the
Adaptive Sensors Group (all based at DCU).
For more information visit;
www.dcu.ie/chemistry/asg
www.ncsr.ie/beaufort
www.clarity-centre.org
16
Appendix I. E. coli and Total Coliforms (TC) counts in water samples
E.coli
Bacterial count, CFU/100 mL
July 29th, 2009
TC
10000
8000
6000
4000
2000
0
Dodder Irishtown
Bridge
Dodder Beaver
Row
Liffey Parliament
Bridge
Tolka Griffith Park
Sampling location
Data1. E. coli and TC count from the samples of Dublin rivers. Sampling locations
according to Map1, Appendix II.
Air temperature
Heavy rain in the last 24 hours
Heavy rain in the last 48 hours
Heavy rain in the last week
18˚C
yes
yes
yes
Dodder Irishtown Bridge
Flow rate
stagnant
Water level
very low
Dodder Beaver Row
Liffey Parliament Bridge
Tolka Griffith Park
fast
slow
medium
low
Comments
Water was very dark and turbid,
petrol-like film on the surface
Water was red in colour
Water was dark
Low turbidity
17
E.coli
August 11th, 2009
Bacterial count, CFU/100 mL
TC
12000
9000
6000
3000
0
Dodder Irishtown
Bridge
Dodder Beaver
Row
Liffey Parliament
Bridge
Tolka Griffith Park
Sampling location
Data 2. E. coli and Total Coliform (TC) count from the samples of Dublin rivers. Sampling
locations according to Map1, Appendix II.
Air temperature
Heavy rain in the last 24 hours
Heavy rain in the last 48 hours
Heavy rain in the last week
Dodder Irishtown Bridge
Dodder Beaver Row
Liffey Parliament Bridge
Tolka Griffith Park
Flow rate
slow
fast
18˚C
no
yes
yes
Water level
low
low
low
Comments
petrol-like film on the surface
Water was red in colour
Water appeared green
Low turbidity
18
E.coli
August 27th, 2009
Bacterial count, CFU/100 mL
TC
8000
6000
4000
2000
0
Liffey Tall Bridge
Liffey Parliament
Bridge
Grand Canal
Kilmainham
Royal Canal
Phibsboro
Sampling location
Data 3. E. coli and Total Coliform (TC) count from the samples of Dublin rivers and
canals. Sampling locations according to Map1, Appendix II.
Air temperature
Heavy rain in the last 24 hours
Heavy rain in the last 48 hours
Heavy rain in the last week
Flow rate
17˚C
no
yes
yes
Water level
Liffey Tall Bridge
Liffey Parliament Bridge
Grand Canal Kilmainham
Royal Canal Phibsboro
Comments
Sample was taken from
the side of the river
Extremely low
Very littered site
Foam noticed downstream,
littered
19
E.coli
Bacterial count, CFU/100 mL
August 31st, 2009
TC
100000
80000
60000
40000
20000
0
Liffey Tall
Bridge
Liffey
Parliament
Bridge
Liffey
Islandbridge
Grand Canal
Kilmainham
Royal Canal
Phibsboro
Sampling location
Data 4. E. coli and Total Coliform (TC) count from the samples of Dublin rivers and
canals. Sampling locations according to Map 1, Appendix II.
Air temperature
Heavy rain in the last 24 hours
Heavy rain in the last 48 hours
Heavy rain in the last week
Liffey Tall Bridge
Liffey Parliament Bridge
Liffey Iselandbridge
Grand Canal Kilmainham
Royal Canal Phibsboro
Flow rate
medium
medium
18˚C
yes
yes
yes
Water level
high
high
high
high
high
Comments
Water appeared dark
green in colour
Water appeared green in colour
Very littered site
Some litter
20
E.coli
September 3rd, 2009
Bacterial count, CFU/100 mL
TC
100000
80000
60000
40000
20000
0
Liffey Tall
Bridge
Liffey
Parliament
Bridge
Liffey
Islandbridge
Grand Canal
Kilmainham
Royal Canal
Phibsboro
Sampling location
Data 5. E. coli and Total Coliform (TC) count from the samples of Dublin rivers and
canals. Sampling locations according to Map 1, Appendix II.
Air temperature
Heavy rain in the last 24 hours
Heavy rain in the last 48 hours
Heavy rain in the last week
14˚C
yes
yes
yes
Water level
Liffey Tall Bridge
Flow rate
fast
Liffey Parliament Bridge
fast
Very high
Liffey Iselandbridge
Very fast
high
Grand Canal Kilmainham
Royal Canal Phibsboro
still
still
high
high
Comments
Water seemed very rough and
dark in colour
Water very brown and turbid,
foam beginning to appear from
upstream
Water appeared brown in color,
very turbid, foam on the
surface (to North bank)
Overflow pipe (origin was
not investigated) hidden
between bushes and
discharging into the river.
On the North bank another
pipe noticed, but no discharge
at the time of sampling
Very littered site
Water was quite clear, debris
present, but mostly vegetation
21
E.coli
TC
12000
9000
6000
Royal Canal
Phibsboro
Grand Canal
The Barge
Grand Canal
Kilmainham
Liffey
Islandbridge
0
Liffey
Parliament
Bridge
3000
Liffey Tall
Bridge
Bacterial count, CFU/100 mL
September 7th, 2009
Sampling location
Data 6. E. coli and Total Coliform (TC) count from the samples of Dublin rivers and
canals. Sampling locations according to Map 1, Appendix II.
Air temperature
Heavy rain in the last 24 hours
Heavy rain in the last 48 hours
Heavy rain in the last week
Liffey Tall Bridge
Flow rate
medium
Liffey Parliament Bridge
Liffey Iselandbridge
Grand Canal Kilmainham
Grand Canal The Bardge
Royal Canal Phibsboro
18˚C
no
yes
yes
Water level
high
low
slow
slow
Comments
Water seemed slightly green in
colour
“normal”
Some foam on top was
noticed, “normal” water colour
Water was very clear
Water was very clear
Water was very clear
22
E.coli
TC
10000
8000
6000
4000
Royal Canal
Phibsboro
Grand Canal
The Barge
Grand Canal
Kilmainham
Liffey
Islandbridge
0
Liffey
Parliament
Bridge
2000
Liffey Tall
Bridge
Bacterial count, CFU/100 mL
September 9th, 2009
Sampling location
Data 7. E. coli and Total Coliform (TC) count from the samples of Dublin rivers and
canals. Sampling locations according to Map 1, Appendix II.
23
E.coli
TC
8000
6000
4000
Royal Canal
Phibsboro
Grand Canal
after The
Barge
Grand Canal
before The
Barge
Grand Canal
Kilmainham
Liffey
Islandbridge
0
Liffey
Parliament
Bridge
2000
Liffey Tall
Bridge
Bacterial count, CFU/100 mL
September 14th, 2009
Sampling location
Data 8. E. coli and Total Coliform (TC) count from the samples of Dublin rivers and
canals. Sampling locations according to Map 1, Appendix II.
24
E.coli
TC
16000
12000
8000
Royal Canal
Phibsboro
Grand Canal
after The
Barge
Grand Canal
before The
Barge
Grand Canal
Kilmainham
Liffey
Islandbridge
0
Liffey
Parliament
Bridge
4000
Liffey Tall
Bridge
Bacterial count, CFU/100 mL
September 23rd, 2009
Sampling location
Data 9. E. coli and Total Coliform (TC) count from the samples of Dublin rivers and
canals. Sampling locations according to Map 1, Appendix II.
25
E.coli
July 14th, 2009
TC
Bacterial count,
CFU/100 mL
20000
15000
10000
5000
Batterstown
"stream"
Dunboyne
roundabaout
Damastown
M50 at
Castelnock
Ashtown
Glasnevin
Woods
Botanic
gardens
0
Sampling location
Data 10. E. coli and Total Coliform (TC) count from the samples of river Tolka in Dublin
and Co. Meath. Sampling locations according to Map 2, Appendix II.
15˚C
yes
yes
yes
Air temperature
Heavy rain in the last 24 hours
Heavy rain in the last 48 hours
Heavy rain in the last week
Botanic gardens
Flow rate
Very fast
Very fast
Glasnevin Woods
fast
Ashtown
slow
M50 at Casteklnock
Slow/stagnant
Damastown
medium
Dunboyne roundabout
stagnant
Batterstown "stream"
Water level
high
Comments
Water visibly turbid,
dumping evidence along the
river, dogs walk along the
park area, industrial estate
on the side of the river
Horses on the riverbank,
livestock had been grazing in
field continuous with river
bank, car wrecked in the
river, turbid water
Foam was noticed on the
surface, greasy look,
discharge flowing form pipe
into the river, “portaloo” on
site of construction staff, very
turbid water
Water appeared eutrophic,
river was used for the
equipment washing, very
turbid water
Turbid water, private dwelling
was noticed immediately
beside river
Water was very shallow, very
little sample was collected,
stream was very overgrown
26
E.coli
July 23rd, 2009
12000
9000
6000
Culcommon
road
Batterstown
Lismahon
road
Comelstown
road
Dunboyne
roundabout
Damastown
Ashtown
Glasnevin
Woods
0
M50 at
Casteklnock
3000
Griffith Park
Bacterial count,
CFU/100 mL
TC
Sam pling location
Data 11. E. coli and Total Coliform (TC) count from the samples of river Tolka in Dublin
and Co. Meath. Sampling locations according to Map 2, Appendix II.
Air temperature
Heavy rain in the last 24 hours
Heavy rain in the last 48 hours
Heavy rain in the last week
yes
yes
yes
Flow rate
Griffith Park
Very fast
Glasnevin Woods
fast
Ashtown
slow
M50 at Casteklnock
Slow/stagnant
Damastown
Dunboyne roundabout
Comelstown road
stagnant
Water level
Comments
Turbid water
dumping evidence along
the river, dogs walk
along the park area,
industrial estate on the
side of the river
Horses on both river
bank, livestock had been
grazing in field continuous
with river bank, faeces,
car wrecked in the river
Grey-brown discharge
flowing form pipe into the
river, “portoloo” on
site of construction staff,
turbid water
Water appeared eutrophic,
pipe discharging into river
from direction of
industrial estate
Construction work being
done on new road:
building a septic tank to
hold run-off from road;
pipe pumping water from
works into river; area of
stagnant water between
river
and
septic
tank
construction
House stable/ ship farm
27
stagnant
Lismahon road - Batterstown
"stream"
Batterstown
Culcommon road
area, water appeared to be
used for animals
Water was very shallow,
very little sample was
collected, stream was
very overgrown, single
dwelling, pipes are directed
onto river
Water was very turbid,
footprints of the cattle in the
river – cattle grazing adjacent
River adjacent to single
dwelling, sheep grazing on
crops beside river, Oily
film on the surface of
water, strong “chemical”
smell – sheep dip or creosote
28
Phosphate concnetration,
mg/L
July 29th, 2009
0.3
0.2
0.1
0
Dodder Irishtown
Bridge
Dodder Beaver Row
Liffey Parliament
Bridge
Tolka Griffith Park
Sampling location
Data 12. Phosphate concentrations in samples from the Dublin Rivers. Sampling locations
according to Map 1, Appendix II.
Air temperature
Heavy rain in the last 24 hours
Heavy rain in the last 48 hours
Heavy rain in the last week
18˚C
no
yes
yes
29
0.80
0.60
0.40
0.20
Da
m
as
to
wn
ne
ro
un
da
Co
bo
m
ut
el
st
ow
n
ro
ad
Li
sm
ah
on
ro
ad
Ba
tte
rs
to
Cu
w
lco
n
m
m
on
ro
ad
Du
nb
oy
no
ck
n
as
te
kl
at
C
As
ht
ow
M
50
ith
G
Pa
la
rk
sn
ev
in
W
oo
ds
0.00
G
rif
f
Phosphate concentration,
mg/L
July 23rd, 2009
Sampling location
Data 13. Phosphate concentrations in samples taken from the River Tolka in Co. Dublin
and Co. Meath. Sampling locations according to Map 2, Appendix II.
Air temperature
Heavy rain in the last 24 hours
Heavy rain in the last 48 hours
Heavy rain in the last week
yes
yes
yes
30
Bacterial count, CFU/100 mL
September 8th, 2009
E.coli
TC
40000
30000
20000
10000
0
Balbriggan river
Portrane outfall site
Sampling location
Data 14. E. coli and Total Coliform (TC) count from the samples in North Co. Dublin.
E.coli and TC in the water sample of Balbriggan River was too numerous to count in 10-1
dilutions, the estimated number exceeds 50,000 CFU/100 mL. Sampling locations
according to Map 3, Appendix II.
Air temperature
Heavy rain in the last 24 hours
Heavy rain in the last 48 hours
Heavy rain in the last week
16˚C
yes
yes
yes
Water level
Balbriggan river
Portrane outfall site
Comments
Sample is taken at green bridge before harbour.
Water very clear, biofouling near blocked pipe.
Site is to rear of St. Ita’s Hospital
Pipe covering in very poor condition,
extensive biofouling, foam build up on rocks
31
E.coli
TC
20000
15000
10000
5000
Toilet
Beach
Low Tide
Toilet
Beach
High Tide
Harbour
Entrance
Ship
Harbour
Bridge
Harbour
Bridge
Green
Bridge
0
Lawlwss
Bridge
Bacterial count, CFU/100 mL
September 15th, 2009
Sampling location
Data 15. E. coli and Total Coliform (TC) count from the samples in North Co. Dublin,
Balbriggan area. Sampling locations according to Map 3, Appendix III.
32
E.coli
Bacterial count, CFU/100 mL
September 17th, 2009
TC
50000
40000
30000
20000
10000
0
Beach River
Incoming
Pipe Incoming
Pipe Crack 1 Low
Tide
Pipe Crack2 Low
Tide
Sampling location
Data 16. E. coli and Total Coliform (TC) count from the samples in North Co. Dublin,
Portrane area. E.coli in the samples from the pipe cracks was above 140,000 CFU/100 mL.
TC in the samples from the pipe cracks was above 700,000 CFU/100 mL. Sampling
locations according to Map 3, Appendix II.
33
E.coli
September 22nd, 2009
TC
Bacterial count
25000
20000
15000
10000
5000
0
Lawless Bridge
Car Park Bridge
River Pipe
Sampling location
Data 17. E. coli and Total Coliform (TC) count from the samples in North Co. Dublin,
Balbriggan area. Sampling locations according to Map 3, Appendix II.
34
Appendix II. Maps of the investigated area.
Map 1. Dublin inner city
Liffey Tall Bridge
Liffey Parliament Bridge
Liffey Iselandbridge
Dodder Irishtown Bridge
Dodder Beaver Row
Tolka Griffith Park
Grand Canal Kilmainham
Grand Canal The Bardge
Royal Canal Phibsboro
Site#
1
2
3
4
5
6
7
8
9
35
36
Map 2. Co. Dublin and Co. Meath
Griffith Park
Botanic Gardens
Glasnevin Woods
Ashtown
M50 at Castelnock
Dumastown
Dunboyne roundabaout
Cowelstown road
Lismahon road - Batterstown "stream"
Batterstown
Culcommon road
Site #
1
2
3
4
5
6
7
8
9
10
11
37
38
Map 3. North Co. Dublin.
Balbriggan river
Portrane outfall site
Balbriggan
Lawlwss Bridge
Green Bridge
Harbour Bridge
Harbour Bridge
LightHouse
Ship
Harbour Entrance
Beach Wall High Tide
Mid Beach High Tide
Toilet Beach High Tide
Mid Beach Low Tide
Toilet Beach Low Tide
Portrane
Beach River Incoming
Pipe Incoming
Pipe Crack 1 Low Tide
Pipe Crack2 Low Tide
Balbriggan
Lawless Bridge
Car Park Bridge
River Pipe
Beach Wall
Site#
1
2
1
2
1
39
40
Map 4. Portrane Waste Water Treatment Works and nearby area (Provided by
Fingal County Council).
Waste Water Treatment Works
Portrane Bathing Water Quality Sampling Point
Donabate Bathing Water Quality Point
Site#
1
2
3
41
Map 5. Portrane waste Water Treatment Works, detailed view (Provided by Fingal
County Council).
Waste Water Treatment Works
Pumping station
Site#
1
2
42
Appendix III. Photographs of the sites.
Photo 1. River Tolka in Griffith Park, easily accessible to the public. Location 6 on Map 1,
Appendix II.
43
Photo 2. The pipe discharging raw sewage waste into the river Tolka.
44
Photo 3. The horse and the faeces near the river Tolka, Ashtown, Dublin. Sampling
location 4 on Map 2, Appendix II.
45
Photo 4. Animal footprints in the River Tolka, Batterstown, Co. Meath. Sampling location
10 on Map 2, Appendix II.
46
Photo 5. Balbriggan Harbour showing path of River Bracken at low tide (above) and high
tide (below). Location 1 in Map 3, Appendix II.
47
Photo 6. Pipe leading to Bracken River in Balbriggan. Location 1 in Map 3, Appendix II.
Photo 7. Outfall pipe in Portrane. Location 2 in Map 3, Appendix II.
48
Photo 8. Exposed cracked sewage pipe, Portrane. Location 2 in Map 3, Appendix II.
Figure 9. Gaping holes in sewage pipe, Portrane. Location 2 in Map 3, Appendix II.
49
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51