Journal of Environmental Protection, 2011, 2, 271-279
doi:10.4236/jep.2011.23030 Published Online May 2011 (http://www.scirp.org/journal/jep)
Copyright © 2011 SciRes. JEP
271
Contamination Sources of Bomuruella Reservoir
at Nuwara Eliya
Randika Anjalie Jayasinghe1*, Nilanthi Janaki Gammanpila Jayaweera Bandara1,
Keerthi Meepe Mohotti2
1Department of Forestry and Environmental Science, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda, Sri
Lanka; 2Tea Research Institute, Talawakale, Sri Lanka.
Email: randij83@gmail.com
Received December 18th, 2010; revised February 5th, 2011; accepted March 8th, 2011.
ABSTRACT
Bomuruella Reservoir in Nuwara Eliya is an important water source in the area which indirectly contributes to the
drinking water supply of the downstream people. Many agricultural lands obtain water from this reservoir and consume
its water for washing and cleaning purposes. This research was focused on identifying the contamination sources of
Bomuruella reservoir and to investigate the suitability of the reservoir as a drinking water source. According to the
water quality analysis, BOD5 and CODMn values of most samp le points did not sa tisfy the specified standa rds of Cen-
tral Environmental Authority, Sri Lanka. Municipal wastewater stream and the stream from the cultivated area re-
corded high BOD5 levels of 7.65 mg/l and 6.55 mg/l respectively in the period of low water level of the reservoir. The
stream from the cu ltivated area reported a high CODMn valu e of 595.74 mg/l during March and the stream from Kan-
dapola plantation recorded a CODMn value of 74.44 mg/l during May. This concludes that the reservoir was contami-
nated with significant loads of organic wastes. Furthermore, the effluent from the leachate treatment plant recorded
higher conductivity, nitrate and CODMn values which indicated that the leachate treatment plant was malfunction-
ing.The main cause of pollution of the reservoir is the discharge of agricultural runoff, raw sewage and wastes which
include domestic, industrial and hospital waste directly into the feeder streams. It can be concluded that if the reservoir
is to be used as a source of drinking water stringent measures have to be taken to control effluents.
Keywords: Water Quality, Contamination Sources, Bod5, Codmn, Leachate
1. Introduction
Bomuruella Reservoir is situated in the Nuwara Eliya
District surrounded by the Kandapola—Seetha Eliya
Forest Reserve and serves as an important water source
in the area. The reservoir constructed and operated by
the Department of Irrigation (ID) is used to augment
the irrigation supplies of the Uma Oya canal irrigation
scheme, a major irrigation scheme in the upper Uma
Oya basin.
The reservoir is situated in a valley surrounded by
hilly areas which consist of Eucalyptus grandis planta-
tion owned by the Department of Forest, a lush Sub
Montane Forest and cultivated areas of tea and vegeta-
bles. Due to steep valley slopes in major parts of the
reservoir catchment the chances of infiltration is re-
duced. The thickness of the soil cover in the area is
relatively thin reducing the capacity to retain infiltra-
tion. The combined effect of these would be rapid run-
off in the catchment. Thus stream flows would be
characterized by large flow volumes during rainy pe-
riods resulting in a high water level in the reservoir,
immediately followed by significantly small flows
when the rains have ceased resulting in a low water
level in the reservoir [1].
Although the Reservoir is not been used as a direct
supplier of drinking water, it indirectly contributes to
the drinking water supply of the downstream people.
Many agricultural lands obtain water from this reser-
voir and consume its water for washing and cleaning
purposes. Bomuruella Reservoir serves as a popular
fishing location among the locals and contributes to the
aesthetic value of the area.
*This study was funded by UNDP/GEF Small Grants Facility program,
SEVANATHA and Research & Development Section of National
Water Supply and Drainage Board.
However, the reservoir is subjected to many con-
tamination sources mainly due to anthropogenic activi-
Contamination Sources of Bomuruella Reservoir at Nuwara Eliya
272
ties. This includes leachate from the Moon Plains land-
fill, runoffs from cultivated lands which may contain
high amounts of fertilizer and pesticides and industrial,
hospital and household wastewater streams. Hence, the
research was carried out to study and identify the con-
tamination sources of the Bomuruella reservoir. The
results were used to evaluate the suitability of water for
consumption and to suggest mitigatory measures to
improve the quality of the water.
2. Methodology
Preliminary field investigations were carried out in Au-
gust and September 2008 to identify the possible loca-
tions for sample collection and to gain a thorough under-
standing about the reservoir environment. Sampling was
carried out each month for a period of seven months
from November 2008 to May 2009.
Sampling was done during both wet and dry periods of
the year. Samples from February 2009 to April 2009
were collected to represent the dry period during which
there was a low water level in the reservoir, whereas
samples in November, December, January and May were
collected to represent the wet period when the water lev-
el was high.
2.1. Sampling Locations
Water samples from the following locations were col-
lected during the study period (Table 1). Sampling loca-
tions of the reservoir were reached by a boat (except for
the reservoir outlet) due to the difficulty in reaching the
locations through the forest and due to time constraint.
Water samples were taken from the side of the boat using
direct sampling method where the sample containers
were directly dipped in to the water. Sampling was done
with care, under the water surface avoiding surface de-
bris and the boat wake.
2.2. Sample Analysis
DO, BOD5, CODMn and all the chemical and biological
parameters were analysed at the National Water Supply
and Drainage Board Laboratory at Thelawala,
Ratmalana. pH and biological analysis were carried
out on the same day of sample collection. Parameters
such as heavy metals and iron (Fe) were measured at the
laboratory of the Department of Forestry and Environ-
mental Science, University of Sri Jayewardenepura, Nu-
gegoda.
The water quality analyses were carried out in accor-
dance with the Standard Methods for the Examination of
Water and Wastewater [2] (Table 2). Values of the pa-
rameters were compared with the Central Environmental
Authority proposed Ambient Water Quality Standards
for inland waters of Sri Lanka [3].
2.3. Statistical Analysis
MINITAB 14 statistical software was used for the statis-
tical analysis of the results. Average values of the dif-
ferent water quality parameters during high water level
and low water level of the reservoir were analysed to
determine whether there is a significant difference of the
parameters between the two periods by using 1-Sample
Wilcoxon test. This is a non-parametric analysis.
Furthermore the average values of each parameter
during wet and dry periods and Central Environmental
Authority proposed ambient water quality standards for
inland waters of Sri Lanka were compared using the
same test to determine whether there is a significant dif-
ference between the observed value of a given parameter
and the corresponding standard level.
3. Results
The water level of the reservoir was high in November,
December, January and May. October, November and
December months recorded high rainfall during the study
period. Although January did not receive a considerable
amount of rainfall, the reservoir water level was high in
January due to the previous months’ high rainfall. Aver-
age results (averaged over the months) obtained from the
water analysis for the high water levels in the reservoir
are summarized below in Tables 3 and 4.
The water level of the reservoir was low in the months
of February, March and April. February and April re-
ceived very low amounts of rainfall according to the
rainfall data. Although during March there was a consid-
erable.
Table 1. Sampling locations.
Sampling locations Identification code
Sampling locations of the reservoir
Reservoir Left bank R1
Municipal and Hospital waste waterfall R2
Small stream from the cultivated areas R3
Housing area R4
Stream through the Kandapola Plantation R5
Middle of the Reservoir R6
Reservoir Right bank R7
Reservoir Outlet R8
Leachate treatment facility
Leachate after treatment (outlet) L2
Other sampling locations
Vegetable washing area V
Ambagasduwa Raw water intake Am
Copyright © 2011 SciRes. JEP
Contamination Sources of Bomuruella Reservoir at Nuwara Eliya
Copyright © 2011 SciRes. JEP
273
Table 2. Test methods.
Parameter Test method
pH pH meter
Turbidity Nephelometric method
Conductivity Conductivity meter
Chemical Oxygen Demand (COD) Titrimetry—K2Cr2O7 method (Closed reflux method)
Total Phosphate as PO4 Spectrophotometric—Ascorbic acid method
Nitrate (as N) Spectrophotometric—Cadmium reduction method
Nitrite (as N) Spectrophotometric—Diazotization method
Sulfate (as SO4) Turbidimetry method
Total coliform Membrane Filter Method (MF—Endo Media)
Feacal coliform Membrane Filter Method (M—FC Media)
Biological Oxygen Demand (BOD5) Titrimetry—Winkler method
Dissolve Oxygen(DO) Titrimetry—Winkler method
Metals Atomic Absorption spectrophotometric method
Table 3. Average results for high water levels.
Sample
Code Temp.
() pH Cond.
(µS/cm),
max
Turbidity
(NTU), max
TDS
(mg/l),
max
Nitrates
(mg/l), max
Nitrites
(mg/l),
max
Dissolved
Oxygen
(mg/l), min
BOD5
(mg/l),
max
COD
(mg/l),
max
R1 17.50 7.34 175.80 4.58 132.15 3.58 0.11 6.80 2.25 12.12
R2 17.00 7.61 190.38 4.23 130.95 2.68 0.13 7.17 4.98 14.22
R3 17.75 7.56 183.53 6.42 131.55 3.38 0.08 7.17 4.20 12.57
R4 17.50 7.56 175.45 3.75 130.00 3.65 0.11 6.93 3.43 18.08
R5 17.50 7.54 175.08 4.58 129.05 3.08 0.09 7.13 5.25 34.59
R6 17.50 7.70 178.35 5.27 131.65 2.88 0.09 6.95 5.07 14.79
R7 17.50 7.42 178.43 4.46 131.25 2.90 0.11 6.82 4.92 20.80
R8 17.50 7.37 182.38 3.95 130.40 3.03 0.24 7.03 6.45 12.70
V 17.75 6.83 77.08 5.35 54.94 2.13 0.01 6.80 1.80 15.10
Am 20.50 7.82 190.45 3.62 138.10 2.75 0.01 6.90 0.80 9.35
L2 17.25 7.56 2310.50 41.13 1921.50 7.85 0.13 0.17 18.50 154.42
Table 4. Average results for high water levels.
Sample
Code Sulfates
(mg/l), max
Total
Coliform in
100 ml
Faecal
Coliform in
100 ml Fe (mg/l)Cd
(µg/l) Cu
(µg/l) Ni (µg/l)Zn (µg/l) Pb
(µg/l) Cr
(µg/l)
R1 31.00 2685 633 0.17 0 0 1.75 43.5 0 2.50
R2 40.25 1763 268 0.12 0.25 0 2.00 4.25 0 0.25
R3 40.00 1383 245 0.15 0 0 3.00 4.25 0 1.25
R4 37.00 3117 286 0.21 0 0 2.25 3.50 0 1.75
R5 41.25 2271 325 0.17 0 0 3.75 3.75 0 2.00
R6 41.00 3285 1001 0.12 0 0 3.00 4.00 0 2.25
R7 40.00 2908 387 0.11 0 0 3.75 5.75 0 2.25
R8 36.00 3618 1226 0.09 0 0 3.75 4.00 0 3.00
V 12.50 * 815 0.43 0 0 4.00 7.75 0 3.50
Am 52.00 21 15 0.66 0 0 1.00 4.00 0 1.00
L2 32.50 TNC * 1.94 0 0 11.25 18.00 11 3.75
Contamination Sources of Bomuruella Reservoir at Nuwara Eliya
274
Rainfall according to the rainfall data, the water level
was low in the reservoir due to the dry weather prevailed
during the period. Average results (averaged over the
months) obtained from the water analysis for the low
water levels are summarized below in Tables 5 and 6.
The ambient water quality standards proposed by the
Central Environment Authority for inland waters do not
specify a particular standard level for temperature [3].
However, all sample locations reported an average tem-
perature above 15˚C during both high and low water lev-
els. According to the proposed ambient water quality
standards, pH range for drinking water with simple
treatment, fish and aquatic life and for irrigation and ag-
riculture is 6.0-8.5 [3]. pH levels of all samples were
within these standards for both high and low water levels.
The maximum conductivity level for drinking water
with simple treatment is 750 µS/cm and the maximum
standard level of conductivity for irrigation and agricul-
ture is 700 µS/cm. Conductivity levels of all reservoir
samples were within these standards for both high and
low water levels and comprise of very low values com-
pared to the standards.
Table 5. Average results for low water levels.
Saple
Code Temp.
(˚C) pH Cond.
(µS/cm),
max
Turbidity
(NTU), maxTDS (mg/l),
max Nitrates
(mg/l), max
Ntrites
(mg/l),
max
Dissolved
Oxygen
(mg/l), min
BOD5
(mg/l),
max
COD
(mg/l),
max
R1 19.67 8.07 198.00 35.63 129.13 3.40 0.09 7.82 5.10 39.28
R2 19.67 7.99 199.33 32.47 130.03 2.77 0.15 7.50 7.65 24.73
R3 20.33 7.94 198.93 49.70 129.77 3.33 0.12 7.48 6.55 224.15
R4 20.33 8.01 204.60 46.00 133.47 3.37 0.16 7.45 7.55 30.36
R5 20.33 8.12 198.13 47.77 129.27 3.57 0.16 7.28 5.10 29.59
R6 19.67 8.22 196.43 39.73 128.03 2.70 0.11 7.72 4.80 28.79
R7 20.33 8.31 195.20 31.10 127.20 2.80 0.14 8.13 2.15 34.30
R8 19.67 7.69 206.10 29.50 134.60 3.67 0.26 6.95 3.90 22.19
V 19.00 7.39 83.40 16.83 53.92 1.77 0.04 6.92 4.00 24.21
Am 22.33 8.09 165.00 2.27 107.22 1.80 - 7.33 0.40 9.98
L2 18.00 7.15 1070.20 102.27 744.97 7.53 0.04 0.10 10.33 48.31
Table 6. Average results for low water levels.
Sample
Code Sulfates
(mg/l), max
Total
Coliform in
100 ml
Faecal
Coliform in
100 ml Fe (mg/l) Cd
(µg/l) Cu
(µg/l) Ni (µg/l)Zn (µg/l) Pb
(µg/l) Cr
(µg/l)
R1 69.00 300 57 0.29 0 0 4.00 1.33 0 4.33
R2 63.67 220 58 1.05 0 0 4.33 1.67 2.67 5.00
R3 77.00 242 25 1.74 0 0 4.00 2.33 0 7.00
R4 75.67 120 29 0.74 0 0 5.00 4.33 1.33 8.33
R5 68.33 100 135 0.37 0 0 4.33 3.33 1.33 6.00
R6 65.33 109 22 0.32 0 0 4.67 1.00 8.00 4.67
R7 65.33 333 59 0.43 0 0 4.33 3.67 0.67 5.00
R8 61.67 322 72 0.43 0 0 5.33 2.67 0 2.33
V 10.00 TNC 182 0.51 0 0 4.33 6.33 0 3.00
Am 10.00 2 Nil 0.13 0 0 6.00 22.00 0 2.00
L2 105.73 TNC * High 0 0 4.33 2.33 0 1.33
Copyright © 2011 SciRes. JEP
Contamination Sources of Bomuruella Reservoir at Nuwara Eliya 275
The proposed ambient water quality standards of the
Central Environment Authority, specify that the accept-
able maximum turbidity level for drinking water with
simple treatment is 5NTU [3]. Turbidity level was sig-
nificantly higher than the standard value in all the reser-
voir samples and sample taken from the vegetable wash-
ing area (V) during low water level. According to the
statistical analysis, turbidity value of low water level
period was significantly higher than the standard level (p
= 0.004 < 0.05).
Moreover, the standards specify that for irrigation and
agriculture, the required maximum TDS level is 500 mg/l.
According to the results, TDS level in all the samples
were lower than the standard level during both low and
high water level periods.
According to the ambient water quality standards the
required maximum nitrate level for drinking water with
simple treatment, fish and aquatic life and for irrigation
and agriculture is 5 mg/l [3]. Nitrate level was lower than
the standard values in all the samples during both high
and low water level periods of the reservoir. Samples
obtained from the reservoir left bank and streams flow-
ing from cultivated area (R3), housing area (R4) and
Kandapola plantation (R5) recorded comparatively high
nitrate levels. Reservoir outlet recorded a high nitrate
level during the low water level of the reservoir.
No specific standard is given for nitrites in the pro-
posed water quality standards for inland waters. How-
ever, according to the results obtained, highest nitrite
level was recorded in the sample taken from the reservoir
outlet.
The permitted maximum sulphate level for drinking
water with simple treatment is 250 mg/l and 1000 mg/l
for irrigation and agriculture. Sulphate level was lower
than the standard values in all the samples during both
high and low water level periods of the reservoir.
According to the ambient water quality standards of
the Central Environment Authority, the required mini-
mum DO level for drinking water with simple treatment
is 6 mg/l and a minimum of 3 mg/l is required for fish
and aquatic life and for irrigation and agriculture [4].
Observed DO levels were higher than the minimum stan-
dard values in all the samples during both high and low
water level periods of the reservoir.
The required BOD level for drinking water with sim-
ple treatment is 3 mg/l. Fish and aquatic life requires 4
mg/l and irrigation and agriculture requires a maximum
standard level of 5 mg/l [3]. BOD level was higher than
the standard value for drinking water with simple treat-
ment in all the samples except for the samples obtained
from reservoir left bank (R1), vegetable washing area (V)
and Ambagasduwa area (Am) during the high water level.
Reservoir right bank and Ambagasduwa samples had a
low BOD value than the standard level for drinking wa-
ter whereas all the other samples had higher values than
the standard level during the period of low water level.
BOD values for low water level period was significantly
higher than the maximum standard level for drinking
water with simple treatment (p = 0.026 < 0.05).
According to the ambient water quality standards of
the Central Environment Authority, the acceptable
maximum COD level for drinking water with simple
treatment and for fish and aquatic life is 15 mg/l [3].
COD level was higher than the standard values for all the
samples except for the sample obtained from the Amba-
gasduwa area during the period of low water level. The
sample obtained from the stream from the cultivated area
(R3) recorded a very high COD level compared to other
samples. During the high water level of the reservoir
samples collected from the housing area (R4), stream
from Kandapola plantation (R5), reservoir right bank (R7)
and vegetable washing area (V) recorded high COD lev-
els. According to the results of 1-Sample Wilcoxon test,
there is a significant difference between the COD values
of high and low water levels in the reservoir (p = 0.011 <
0.05).
Total Coliform counts of high water level of the res-
ervoir were extremely higher than the Coliform counts
recorded in the low water level period. Month of De-
cember recorded the highest Coliform counts of the
study period. Sample obtained from the vegetable wash-
ing area recorded the highest Coliform count which is
78,400 in 100 ml. Some of the water samples did not
give an exact count due to the presence of other micro-
organisms on the growth media. According to the results
of 1-Sample Wilcoxon test, there was a significant dif-
ference between the average Coliform counts of high and
low water levels in the reservoir (p = 0.009 < 0.05).
Faecal coliform counts of high water level of the res-
ervoir were extremely higher than the faecal coliform
counts recorded in the low water level period. Month of
December recorded the highest faecal coliform counts of
the study period. Sample obtained from the reservoir
outlet recorded the highest average faecal coliform count
during the high water level period. In addition, vegetable
washing area (V) recorded higher faecal coliform counts.
Water samples obtained from Amabagasduwa (Am) re-
corded the lowest faecal coliform counts.
According to the ambient water quality standards of
the Central Environment Authority, the desirable highest
Iron concentration for drinking water with simple treat-
ment is 3 mg/l and the maximum permissible level is 10
mg/l. A maximum of 3 mg/l is required for fish and
aquatic life [3]. Iron level was lower than the maximum
standard values in all the samples during both high and
low water level periods of the reservoir. According to the
Copyright © 2011 SciRes. JEP
Contamination Sources of Bomuruella Reservoir at Nuwara Eliya
276
results of 1-Sample Wilcoxon test, there was a signifi-
cant difference between the Iron values of high and low
water levels in the reservoir (p = 0.047 < 0.05).
Lead was detected only in the month of April 2009 in
the samples obtained from the housing area and the Kan-
dapola plantation stream. Samples obtained from the
middle of the reservoir and reservoir right side bank also
recorded lead during the same month. Apart from this,
Lead was not recorded in any of the sample locations
during the study period.
The acceptable maximum chromium concentration for
drinking water with simple treatment is 50 µg/l. A max-
imum of 2 µg/l is acceptable for fish and aquatic life.
Chromium level was lower than the maximum standard
value for drinking water with simple treatment in all the
samples during the two months. However, most of the
samples recorded a higher chromium level than the re-
quired standard for fish and aquatic life in these two
months.
Remedial actions to clean up polluted sites and water
bodies are generally much more expensive than applying
measures to prevent pollution from occurring. Thus, ap-
proaches to water pollution controls that focus on
wastewater minimisation, recycling of waste products,
etc., should be given priority over traditional treatments.
Industrial establishments should establish proper treat-
ment plants to treat their wastewater. Municipal council
and the Central Environmental Authority should monitor
the discharge of wastewater from such establishments
regularly.
An increasing proportion of water pollution originates
from diffuse sources, such as agricultural use of fertiliz-
ers. The principle of “best environmental practice”
should be applied to minimise non-point source pollution.
Good agricultural practices that address the causes of
water pollution from agriculture such as type, amount
and time of application of fertilisers, manure and pesti-
cides can give guidance to farmers on how to prevent or
reduce pollution of the reservoir which occurs due to
excessive use of agrochemicals.
Wetlands are commonly recognized as serving a vital
role not only for fish and wildlife, but also for pollution
filtration and flood control. When runoff water carrying
nutrients and sediment circulates through a wetland, the
sediment settles and the plants take up and use the nutri-
ents before they can run into the reservoir. Hence, it is
highly important to protect the wetland area surrounding
the Bomuruella reservoir.
Moon Plains landfill which is located in the upstream
of the reservoir cannot be considered as a sanitary land-
fill due to poor management. Waste is haphazardly
dumped all over the landfill. A soil cover is not used on
top of the wastes which lead to emission of large
amounts of leachate. It could be observed that run off
through the waste materials were flowing from the sides
of the landfill without entering the treatment pond. In
addition the treatment pond is not cleaned or maintained
properly which has led to the malfunctioning of the
treatment plant. Hence, it is recommended that the au-
thorities should take necessary actions to manage the
landfill in a proper manner and to upgrade the treatment
plant.
People living in the vicinity of the reservoir should be
made aware of the importance of the reservoir. It is im-
portant to utilise a participatory approach which involves
raising awareness of the importance of water pollution
control among policy makers and the surrounding com-
munity. Decisions should be taken with the involvement
of all the groups affected by the water pollution of the
reservoir. This includes CEA, local authorities, NGO’s,
National Water Supply and Drainage Board, people in
the vicinity and the consumers of water from the Uma
Oya water supply scheme.
Further studies should be carried out to determine the
pesticide residuals and algal counts in reservoir water.
These studies will provide a better idea on the level of
pollution from agrochemicals and the level of eutrophi-
cation respectively. The water of the reservoir is not
suitable for drinking purposes with either simple or con-
ventional treatment. Hence, it is recommended to utilize
a more advance water treatment method to treat the water,
if the reservoir is to be used as a drinking water source.
4. Discussion
Bomuruella Reservoir is subjected to contamination from
different sources in the surrounding area. This includes
the landfill leachate treatment plant, vegetable washing
area, Municipal wastewater stream, surface water from
the cultivated areas and Kandapola plantation and the
run-off water streams from the housing area.
The pH of most natural waters is between 6.0 and 8.5
although lower values can occur in dilute waters high in
organic content and higher values in eutrophic waters.
For example, samples collected at the influx point to
Barracks Plain reservoir in Nuwara Eliya had zero dis-
solved oxygen with relatively high pH values [4]. How-
ever, water samples analysed during this research did not
report such extreme pH values.
According to Akan, Abdulrahman, Dimari and Ogug-
buaja, electrical conductivity of water is a useful and
convenient indicator of its salinity or total salt content [5].
The conductivity of most freshwaters ranges from 10 to
1000 μS/cm, but may exceed 1000 μS/cm especially in
polluted waters or those receiving large quantities of land
run-off. The conductivity of all the samples were below
200 μS/cm. This is considerably low compared to the
Copyright © 2011 SciRes. JEP
Contamination Sources of Bomuruella Reservoir at Nuwara Eliya 277
standard for drinking water with simple treatment and
the required standard level of conductivity for irrigation
and agriculture.
Turbidity is of considerable interest because of the ef-
fects on light transmission and water clarity [6]. Normal
turbidity values range from 1 to 1000 NTU and levels
can be increased by the presence of organic matter pol-
lutants, other effluents or run-off with high suspended
matter content. The higher levels of turbidity reported
during the research can be due to water being stagnant
with low rates of flushing which may have resulted in
very fine particulate matter held in suspension during the
low water level. Biological activities that prevail during
warm water conditions may also have contributed to the
high turbidity levels.
The same author states that total suspended solids
(TSS) are a major transport mechanism for nutrients and
contaminants and deposit in reservoirs, thus displacing
valuable water storage [6]. According to the results ob-
tained during the study, there was no significant differ-
ence between the TDS values of high and low water lev-
els in the reservoir.
When influenced by human activities, surface waters
can have nitrate concentrations up to 5 mg/l NO3-N, but
often less than 1 mg/l NO3-N. Concentrations in excess
of 5 mg/l NO3-N usually indicate pollution by human or
animal waste or fertiliser run-off. According to the study,
average nitrate variation of water in the reservoir did not
exceed the standard levels. A similar study carried out in
Bomuruella by NWS&DB reported that results of ni-
trates and nitrites were well below the standard limits for
drinking water [7]. However, some samples collected
from streams flowing from the cultivated area (R3),
housing area (R4) and Kandapola plantation (R5) have
recorded nitrate levels which was higher than 4 mg/l.
This may be due to the agrochemical runoff from these
areas.
Sulphate is naturally present in surface waters as
. In this study, water samples recorded a very low
concentration of sulphate level compared to the standard
levels. March, April and May recorded higher levels of
sulphates compared to months from November to Febru-
ary. High sulphate levels may be due to high concentra-
tions of solid waste materials from households and par-
ticulate matter present in the reservoir due to low flowing
of water during these months.
2
4
SO
The dissolved oxygen concentration depends on the
physical, chemical and biochemical activities in the wa-
ter body and provides a good indication of the quality of
that water. According to a study carried out by Parana-
gama in Kandy Lake, the dissolved oxygen levels varied
from 2 to 7 mg/l which indicated that there is no stratifi-
cation in the lake [8]. However, in this research all the
samples recorded DO levels higher than 6.5 mg/l
throughout the study period. This may be due to aeration
and circulation that involves moving of the water body
thus adding oxygen which increases dissolved oxygen
levels. Turbulence of surface water layers due to the ef-
fect of wind will cause the water to be saturated with
oxygen resulting in high DO levels.
According to Ileperuma, urban and industrial dis-
charges from inadequate waste treatment and disposal
facilities contribute significant quantities of oxygen de-
pleting substances [9]. This was observed in samples
obtained from the Municipal wastewater stream and the
stream from the cultivated area which recorded high
BOD5 levels of 7.65 mg/l and 6.55 mg/l respectively in
the period of low water level of the reservoir. Moreover,
the sample collected from the housing area recorded a
high BOD5 level of 7.55 mg/l during the same period.
Domestic sources, i.e. from the settlements along the
reservoir contribute to the BOD5 level significantly due
to poor housekeeping and improper sanitary conditions.
According to a study carried out by Ileperuma, the
samples obtained from Barrack’s Plain reservoir had
high CODMn values indicating increased contamination
from organic wastes [10,11]. Similar results were re-
ported in this study. Diffuse pollution caused by drainage
containing fertilisers and agrochemical residues from
cultivated areas most likely have resulted in the high
CODMn levels observed in the samples collected from
the stream flowing through the cultivated area and
stream flowing through the Kandapola plantation. Stream
from the cultivated area reported a CODMn value of
595.74 mg/l during the month of March. Kandapola
plantation recorded a CODMn value of 74.44 mg/l dur-
ing May.
As mentioned by Abel in his book, Water Pollution
Biology, the coliform group of bacteria is the principal
indicator of suitability of water for domestic or other
uses. Total coliform bacteria occur in both sewage and
natural waters. Some of these bacteria are excreted in the
faeces of humans and animals, but many coliforms are
heterotrophic and are able to multiply in water and soil
environments [12].
Highest numbers of coliforms were recorded in the
month of December. This may be due to the high rains
which prevailed at the time of sampling. Domestic
sources, i.e. from the settlements along the reservoir
contribute to the coliform level significantly due to poor
housekeeping and improper sanitary conditions which
uses the reservoir as the ultimate disposal site. The high-
est coliform number of 78,400 in 100 ml was recorded in
the sample obtained from the vegetable washing area.
This small stream flows through an area with few
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Contamination Sources of Bomuruella Reservoir at Nuwara Eliya
278
households which may be disposing their septic tank
waste directly to the stream.
Escherichia coli are present in very high numbers in
human and animal faeces and are rarely found in the ab-
sence of faecal pollution. Hence, Escherichia coli is con-
sidered the most suitable index of faecal contamination.
Escherichia coli occur in high numbers in human and
animal faeces, sewage and water subject to recent faecal
pollution [13].
Faecal pollution may occur because of poor commu-
nity facilities for waste disposal, inadequate collection
and treatment facilities and the on-site sanitation facili-
ties (such as latrines) which drain directly into the reser-
voir and streams. Highest numbers of faecal coliforms
were recorded in the sample obtained from the reservoir
outlet. This may be due to the outlet stream being pol-
luted by animal and human faecal matter. In addition, the
vegetable washing area (V) recorded a higher number of
faecal coliforms which confirmed that the water is being
polluted by human faecal matter.
Some metals such as Mn, Zn and Cu, when present in
trace concentrations are important for the physiological
functions of living tissue and regulate many biochemical
processes. The same metals, however, discharged into
natural waters at increased concentrations in sewage,
industrial effluents or from mining operations can have
severe toxicological effects on humans and the aquatic
ecosystem [14].
Trace metals such as cadmium, copper, chromium,
nickel, lead and zinc were analysed during this study.
Cadmium was detected only once and that was in the
municipal wastewater stream. Lead is used as an additive
in petroleum for automobiles and is emitted to the at-
mosphere in their exhaust gases, thereby entering the
hydrological cycle. Lead was detected in streams from
the Kandapola plantation and from the housing area.
Lead was found to be present in the samples drawn from
the middle of the reservoir and the right side bank of the
reservoir in low concentrations.
The most highly detected trace element in the water
samples was zinc. Zinc is an essential trace element
found in virtually all water in the form of salts or organic
complexes. However, zinc concentrations can be much
higher as a result of dissolution of zinc from metal ap-
pliances which uses zinc as a galvanizing agent.
The leachate from the landfill is collected and intro-
duced to a leachate treatment facility. This is a combine
system which consists of a coconut fibre biological con-
ductor, a charcoal filter and a wetland. The treated
leachate is released to a small stream approximately 500
m below the valley which finally flows in to the reservoir
[15]. Treated leachate values were compared with the
Central Environmental Authority wastewater discharge
standards into sensitive waters (Class II waters). Dis-
solved oxygen levels of treated leachate were very low in
both periods and did not exceed 0.25 mg/l.
Significant concentrations of heavy metals were not
detected in treated leachate. However, high concentra-
tions of iron were detected in the leachate samples.
Ammonia readily dissolves in water which may have
resulted in high levels of ammonia producing a pungent
odour near the treatment plant.
Total Coliform levels of leachate samples were not
countable during most of the months due to the presence
of other microorganisms on the growth media. However,
E-coli levels were higher than the standard levels which
confirm the presence of faecal matter in the leachate. The
highest E-coli amount was recorded in the treated
leachate sample obtained during the month of January
which was 2000 E-coli in 100 ml. High amounts of
E-coli were recorded during the rest of the months which
is higher than the acceptable level of 40 E-coli in 100 ml.
5. Conclusions
There are many sources which contaminate the Bomuru-
ella reservoir. Municipal wastewater stream carry sewage
effluents, urban drainage and other collected wastewaters
However, the impact from this stream is considerably
mitigated as it flows for a considerable distance through
the forest prior to entering the reservoir as a waterfall.
Hence, this wastewater stream is subjected to a natural
purification.
Tea and vegetable cultivation is practiced extensively
in the upstream of the reservoir and it contributes to the
land run-off associated with excessive land clearance for
cultivation. Other major source of pollution is the stream
flowing through the Kandapola plantation which is the
second largest tributary that flows to the reservoir and it
carries a considerable load of agrochemical run off.
Housing area contributes to the organic load of the res-
ervoir due to the disposal of domestic wastes and poor
sanitary conditions. Often household refuse is dumped in
to the reservoir. The households which belong to the
estate sector lack proper sanitation and most of the
households have directed their septic tank wastewater
flow to the reservoir.
Vegetable washing area which is located upstream of
the reservoir recorded high levels of phosphate which
indicates that excess fertlisers deposited on vegetables
are washed away in water. Septic tanks of some nearby
houses are directed to this water flow. Hence, there is a
possibility of this stream to contain pathogenic microor-
ganisms and consuming of contaminated water to wash
vegetables can cause health risks to consumers.
Municipal solid waste of the Nuwara Eliya area is
dumped in the Moon plains landfill site. Land disposal
Copyright © 2011 SciRes. JEP
Contamination Sources of Bomuruella Reservoir at Nuwara Eliya
Copyright © 2011 SciRes. JEP
279
site is poorly planned and controlled resulting in the
formation of leachate which poses particular risks of
contaminating the water sources.
According to this research, contamination sources
identified as polluting the reservoir has a severe impact
on the water quality of the reservoir. The main cause of
pollution is the discharge of agricultural runoff, raw
sewage and wastes which includes domestic and indus-
trial waste directly into the feeder streams. Hence, it can
be concluded that the water of the reservoir is not suit-
able for drinking purposes with either simple or conven-
tional treatment. It can be further concluded that, if the
reservoir is to be used as a source of drinking water
stringent measures should be applied to control effluents.
REFERENCES
[1] Manikawita Hydropower Development (PVT) Ltd., “Fi-
nal Report of the Proposed Bomuruella Mini Hydropower
Project, Hydrological Study,” Environmental Impact As-
sessment, 2004, pp. 1-22.
[2] APHA, “Standard Methods for the Examination of Water
and Wastewater,” 20th Edition, American Public Health
Association, American Water Works Association and
Water Environment Federation, Washington D C, 1998.
[3] Central Environmental Authority, “Proposed Ambient
Water Quality Standards for Inland Waters of Sri Lanka,”
Environment Action 1 Project (funded by ADB), Co-
lombo, 2001.
[4] JICA, “The Study on Greater Kandy and Nuwara Eliya
Water Supply and Environmental Improvement Plan in
the Democratic Socialist Republic of Sri Lanka,” Vol. 5,
Nippon Jogesuido Sekkei CO., LTD., Hyderabad, 1999
[5] J. C. Akan, F. I. Abdulrahman, G. A. Dimari, V. O.
Ogugbuaja, “Physicochemical Determination of Pollut-
ants in Wastewater and Vegetable Samples along the Ja-
kara Wastewater Channel in Kano Metropolis, Kano
State,” European Journal of Scientific Research, Vol. 23,
No. 1, 2008, pp. 122-133.
[6] Dortch, M. S., “Water Quality Considerations in Reser-
voir Management,” US Army Engineer Waterways Ex-
periment Station, Vicksburg, 1998, pp. 32-38.
[7] National Water Supply and Drainage Board, “Water
Quality Reports, Bomuruella,” Central Laboratory, The-
lawala, Ratmalana, 1997.
[8] P. N. Paranagama, “Zooplankton as Bio-Indicators of
Eutrophication and Possible eutrophication Controlling
Measures for Kandy Lake,” 2002.
[9] O. A. Ileperuma, “Environmental Pollution in Sri Lanka:
A Review,” Journal of National Science Foundation, Vol.
28, No. 4, 2001, pp. 301-325.
[10] O. A. Ileperuma, “Report on Water quality Examination
in the Kandy and Nuwara Eliya Districts,” First Phase
(Dry Season), 1998a.
[11] O. A. Ileperuma, Report on Water quality Examination in
the Kandy and Nuwara Eliya Districts, Second Phase
(Rainy Season), 1998b.
[12] P. D. Abel, “Water Pollution Biology,” Ellis Horwood,
New York, 1989.
[13] WHO, “Guidelines for Drinking Water Quality,” 3rd
Edition, Incorporating the First and Second Addenda,
Recommendations, Vol. 1, World Health Organization,
Geneva, 2008.
[14] R. Helmer and I. Hespanhol, (Eds.), “Water Pollution
Control—A Guide to the Use of Water Quality Manage-
ment Principles,” United Nations Environment Pro-
gramme (UNEP) and World Health Organization, 1997.
[15] JICA Study Team, “Improvement Project of the Moon
Plains landfill site in Nuwara Eliya,” Environmental Im-
pact Assessment, Kokusai Kogya Co., Ltd., Tokyo, 2003.