Salinity variation and pollution of the Negombo estuary

Abstract

Negombo estuary. which is 3170 ha in extent, serves important economic functions including fishing and tourism. It is characterized by high secondary production rates reflected in important biomass values for benthic and pelagic organisms. Estuarine plants and animals are adapted to high environmental variability and possess potentially valuable genetic characteristics. However it is under heavy and increasing pressure li'0111 human activities since it drains water carrying nutrients, organic matter and toxic. materials [rom the terrestrial environment .and the river system to the sea. The disposal of waste oil from the fishing anchorage located at the inlet and the direct discharge of partially and untreated effluents from the Ekala and Katunayake industrial zones are the major contributors of .pollution. The ad-hoc expansion of piers and landing points has lead the alterations in the flow patterns and thus the sedimentation in the channels. Newly formed sand shoals have· obstrncted the previously navigable areas. Unplanned development, unauthorized encroachments to the water body and the siltation have reduced the effective water area by 791 ha during the last three decades. The eventual fate of this basin estuary would be degradation by sedimentation and pollution.