Evaluating Water Quality in Northern and Eastern Coastal Zones of Sri Lanka: A Baseline Study for Environmental Monitoring and Conservation

The coastal area of Sri Lanka, spanning approximately 1,650 km, serves as a major source of livelihood, habitat, tourism, aquaculture, and trade. Although the coastal region provides numerous benefits to nearly 55% of Sri Lanka’s population, it faces severe threats from factors such as aquatic pollution, coastal erosion, ecosystem degradation, urbanization, and sand mining. To ensure ecosystem stability and conserve the coastal environment, it is crucial to conduct environmental monitoring of coastal waters. However, a significant number of water quality assessments conducted so far have primarily targeted the Western and Southern coastal zones of Sri Lanka. This study, therefore, aims to assess the marine water quality in selected locations (26 locations in total) within the Northern (Mannar, Pooneryn, Kilinochchi, Jaffna, and Mullaithivu) and Eastern (Trincomalee) coastal zones. The results showed statistically significant differences in TDS (P = 0.004), COD (P = 0.036), and nitrite levels (P = 0.009) between all the locations. However, no significant variation in COD was observed in the HSD test. Heat map analysis of the water quality index model indicated that some locations in Mannar, Pooneryn, and Jaffna had very poor water quality, while Trincomalee and Mullaithivu exhibited moderate to good water quality in selected locations. Overall, these findings provide a clear understanding of the current water quality status in each of the selected locations. Therefore, it can be concluded that regular water quality monitoring and the application of the Water Quality Index approach should be conducted in each coastal district. This will help to develop a robust database that can serve as baseline information for coastal ecosystem management, conservation efforts, and emergency mitigation measures, such as oil spills or ship fire incidents.