Abstract:
In this study the water quality of Moragoda Eia located in the Galle town was
evaluated using graphical and statistical analysis of water quality data at 14
sampling points along the stream. Principal Component Analysis was used to obtain
the correlation matrix of all the parameters. The sampling points were selected
according to the land usage pattern such as industrial, institutional, commercial,
residential and agricultural areas; general hydraulic conditions such as flow
directions and flow velocities; the locations of sewer outfalls along the stream,
sanitary bypasses and the locations of solid waste deposits with a high content of
organic silt and matter. The study revealed that the stream had a relatively high
pollution level. The degree of pollution decreased along the river from downstream
to upstream. Different segments of the stream got polluted to different degrees. The
level of pollution was highly dependent on the parameter of concern.
There was a close relationship between the water quality of each sampling point and
the respective condition in the surrounding area. Mean values of COD and BOD5
were 127.5mg/L and 14.8 mg/L, respectively. Mean values of fecal and total
coliforms were 47 and 23471 colonies/100 mL, respectively. Prevailing BOD5,
COD and the total coliform content exceeded the ambient water quality standards
for inland waters in Sri Lanka. The mean fecal coliform value did not satisfy the
ambient standards of fecal coliform content for the activities other than irrigations
and agricultural needs. Overall the water quality was lower than the demanded
quality of water for many activities such as drinking, bathing, irrigation and
recreational activities. It is concluded that the water quality deterioration of
Moragoda Ela may be attributed to the illegal discharges from a large number of
industries, institutions and commercial establishments, high population density and
the illegal community activities.