Abstract:
Maduganga estuary and mangrove islets are a complex coastal wetland ecosystem
situated in the Galle District of Southern Sri Lanka. Maduganga estuary and mangrove
islets system which is located in Galle district of Sri Lanka were chosen for the study
(6°18’ N, 80°03’ E). The total area of the estuary is 915 ha, of which 770 ha consist of
open water, while islands account for 145 ha. The ecosystem is identified to be
threatened by human activities carried out inside and around the ecosystem. Continuous
monitoring and conservation activities are necessary for this ecosystem to sustain under
current conditions. In this background this study focuses on monitoring and evaluating
spatial variation of water quality in Maduganga lagoon, estuary and canal connecting to
sea.Twenty locations were selected for studying the water quality and standard methods
was used for water quality analysis. The water quality at each location of Maduganga
estuary is complied with proposed ambient water quality standards for inland waters (Sri
Lanka) (Aquatic life category). However each parameter shows a clear increase at the
sampling location in boat ferry. It might be an initial indication of pollution of
Maduganga estuary water near boat ferry. Further this location is very close to the sea
outfall of the water body. Other than that a location near a bathing point is also showing
a high chemical oxygen demand. Further, this point is located at a corner of the water
body making water stagnant. It might be one of the reasons for observed high chemical
oxygen demand. Observed increase in salinity and chloride is normal when it is close to
river outfall. Further a cluster analysis was carried out on the results and it shows that
upstream of Maduwa and downstream of Maduwa can be identified as two clusters
roughly.