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Water bodies heavily polluted by heavy metals, new study reveals
Evidence continues to build regarding the dismal quality of Sri Lanka’s water bodies: a new scientific study around Kerawalapitiya and Muthurajawela has found canals to be heavily contaminated with high concentrations of heavy metals.
The environmental impact assessment (EIA) report on the proposed 350MW regasified LNG plant at Kerawalapitiya has been released for public comment. While it does not envisage a significant effect on surface or groundwater from the project, the study provides insight into water quality in the area. Samples were drawn from canals, wetlands, marshlands and boreholes.
The canal water showed high concentration of heavy metals, the EIA states. This could be because it was contaminated by industrial wastewater. But Kerawalapitiya is also used for solid waste disposal via open dumping. The release of leachate containing heavy metals to surface water is “more probable” while the addition of metal irons by groundwater to surface water bodies like canals is also likely.
Metallic iron concentration was high compared to other freshwater and groundwater sources in the area. “It can be reasonably concluded that there can be other sources of pollution of industrial nature than the contribution from the ground (groundwater) for metallic ions found in surface water (in canals),” the report says.
Interconnected waterways hook up with the Dutch Canal to the east of the project sight and Hamilton Canal to the west, which in turn connects to the sea at several locations. During dry weather, the canals mostly hold stagnant, polluted water. During wet weather, large quantities of runoff enter the Muthurajawela marsh and swell the canals.
The Central Environmental Authority’s ambient water quality standards issued in November 2019 categories water as that which requires simple treatment for drinking; that which shall be bathing and contact recreational water; water suitable for aquatic life; a water source that requires general treatment for drinking; water suitable for irrigation and agriculture; and water of minimum quality that doesn’t fit into the above categories.
Quality data from canals indicated pollution of such levels that the water was not suitable for any of these uses. “Water quality data are also below the minimum quality requirement,” the EIA says.
There was also “an excessive amount of biological matter than what can be expected of a normal surface water body”. This information, when combined with total coliform [bacteria found in animal and human faeces] and E-coli [bacterial that live in the intestines of animals and humans] levels, highlights the possibility of contamination with sewage and excreta.
The groundwater, too, is polluted and not suitable for any of the uses described by the CEA. Some samples indicated heavy metal contamination and “very low dissolved oxygen content which makes the entry of heavy metals to groundwater quite possible”.
Total coliform and E-coli levels are high and “comparable with surface water”. This pointed to the possibility of contamination with sewage or excreta. Meanwhile, communities around the tested areas had no method to safely dispose of solid household waste as the Wattala Pradeshiya Sabha did not provide a facility. So some households burned garbage within their premises but the majority dumped it into bare lands or the nearest common storm water drainage canal.
The Sunday Times recently reported that Sri Lanka’s freshwater sources are now so polluted that the National Water Supply and Drainage Board (NWSDB) is spending increasingly more money to refine drinking water.
In 2019, the National Audit Office revealed that the Kelani River, which supplies drinking water to 80 percent of the Western Province’s population, was a stew of pollutants including sewage and chemicals. There are 10,511 factories near the river and the disposal of waste from multiple sources meant its water was not suitable for drinking, bathing or entertainment with just minor purification.
Also in 2019, an EIA on the ‘Sri Jayawardenapura Kotte Wastewater Collection, Treatment and Disposal Project’ showed that at least six tons of bio solids and 18,000 cubic meters of untreated or partially treated wastewater were discharged continuously into the ground every day in that region.