Assessment of the Contamination Level of Water at Collection Points and Determination of the Major Sources of Contaminants in West Shoa, Dendi District
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Date
2008-10
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Addis Ababa University
Abstract
Globally, 1.1 billion people rely on unsafe drinking water sources from lakes, rivers, and
open wells. Studies have confirmed that water related diseases not only remain a leading
cause of morbidity and mortality worldwide but that the spectrum of disease is expanding
and the incidence of many water related microbial diseases are increasing. This study was
conducted to assess contamination levels of water and to determine the major sources of
contaminants at collection points.
Three springs and four sites of a river in Yubdo-Legebatu PA were selected for this study.
Representative samples from the water bodies and livestock feces were collected and
analyzed at AAU, Department of Biology, Applied Microbiology Laboratory. The levels
of contamination were determined on the bases of total coliform(TC), fecal coliform(FC)
and fecal Streptococcus(FS) from the water and livestock fecal samples following the
membrane filtration method. Major sources of contaminants were investigated by using
the ratio of fecal coliform to fecal Streptococcus for water samples.
Water analysis demonstrated that all water sources in the study area were contaminated
with total coliforms. Except the samples from the upper river site, of which, 91.7% was
contaminated, all the others were 100% contaminated with total coliforms. Out of the
samples studied, 100% of spring site 1, spring site 2, spring site 3, river site 1 and river
site 3, 83.3% of river site 2 and 91.7% of upper river sites had unacceptable levels of total
coliforms. Likewise, all water sources were 100% contaminated with fecal coliforms,
except that of river site 2 and upper river site which had 91.7% and 83.3% of
contamination level, respectively. Out of the samples considered, 100% of the samples
from spring site 1, spring site 2, spring site 3, river site 1 and river site 2, 91.7% of river
site 3 and 83.3% of upper river site samples were above the limits set by Ethiopia
Ministry of Water Resources and WHO. Analysis for fecal streptococci revealed that
100% of the samples from spring site 1, spring site 2 and river site 2, 91.7% of spring site
3, 75 % river site 1 and 58.3% of upper river site samples were contaminated with these
bacteria. Out of the samples observed for fecal streptococci, 91.7% of spring site 1 and
spring site 3, 66.8% of river site 1 and river site 3, 83.3% of spring site 2 and river site 2
and 58.3% of upper river sites had unacceptable levels of contamination. There was a
significant difference in the average counts of TC, FC and FS among all water sites.
Average concentrations of TC, FC and FS in spring site 3 were significantly higher than
all other water sample sites.
Fecal coliform - fecal streptococci ratios in water sources of this study showed that 100%
indicated enteric contamination from domestic animal wastes.
The highest median and maximum concentrations of total coliforms in the livestock feces
were 3.25 x107 cfu/g and 4.3 x107 cfu/g, from goat and sheep fecal samples at river site 2
and spring 2, respectively. The highest median and maximum counts of fecal coliforms
were 2.05 x107 cfu/g and 2.4 x107 cfu/g, from goat and sheep fecal samples at river site 2
and spring 2, respectively. The highest median and maximum concentrations of fecal
Streptococcus were 1.6 x107 cfu/g and 3 x107 cfu/g, from cattle fecal samples at river site
1. The highest load of contaminants in the water sources could be derived from cattle
wastes.
High concentrations of bacterial indicators in all water sources of this study area
suggested the presence of pathogenic organisms that constitute a threat to anyone
consuming or in contact with these waters. The potential source of enteric organisms’
contamination of these water sources could be mainly explained by the predominance
absence of fencing of watering points that could protect the entrance of animals, open
area defecation and drawing water with unclean cups. Therefore, protection of water
sources accompanied by sanitation and hygiene promotion programs can improve the
hygiene quality of rural water sources, where disinfection is not feasible.
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Biology