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WHO has documented that pathogenic and non-pathogenic microorganisms are usually
present in recreational waters and the sources of microorganisms are mainly from
sewage discharge, industrial processes, agricultural processes and livestock. Due to
consumption of contaminated water, the mortality of water associated diseases are in
increasing trend and it was estimated that more than 5 million people per year. From
these, more than 50% are microbial intestinal infections such as gastroenteritis,
salmonellosis and shigellosis. Kelani River Basin is the second largest watershed in the
country and it plays an important role in relation to the natural, economical, agricultural
and social background of the country. It starts from Nallathanniya at the central
highland western border of the wet zone and end up at the most populated and
economically important administrative district, Colombo. River basin covers nearly
seven districts that including most popularized and industrialized districts along with
25% of population among total population receive drinking water supply from the
Kelani River particularly the capital city Colombo. Therefore water quality monitoring
in this river basin is a priority to safeguard the health of people who drink water from
Kelani river. Due to lack of information on surface water quality data related to
pathogenic bacteria, the present study was focused to identify the occurrence of
pathogenic bacteria in the surface water sources for both dry and wet seasons of the
Kelani River Basin. Salmonella spp., Shigella spp., Campylobacter spp., total coliform
and feacal coliform bacteria were analyzed along with twelve physico-chemical
parameters using standards methods. Forty five sampling locations in the river basin
were studied during the January 2015 to December 2015 to cover both dry and wet
seasons. The results showed that the entire Kelani River Basin was contaminated with
total and feacal coliform bacteria (colony count-200<) and bacterial counts were not
within the SLS (Sri Lanka Standards) and WHO guideline values for drinking water. It
was detected that twenty six sampling locations were positive for Salmonella spp. and
three were positive for Campylobacter spp. during the study period. It was found that,
bacterial contamination was high during the wet season (42%) than dry season (33%)
except Campylobacter spp. and interestingly Shigella spp. was not recorded either dry
or wet period during the study period. ANOVA test was applied to see the
differentiation between two seasons and a significant difference between two seasons
was detected (0.05>p).
