KRISHNAGIRI: Sewage discharge from Bengaluru is the reason for foaming at Kelavarapalli Dam in Hosur and the increased growth of ‘water hyacinth’ in the KRP Dam, said Collector C Dinesh Kumar.
In a press statement, the collector stated, “Thenpennai River originates in Nandi Hills near Bengaluru and flows through Hosur and passes through Kelavarapalli Dam. Due to untreated or partially treated water being discharged from factories in Bengaluru, foaming occurs at the dam. As a result, the CPCB has deemed the area a ‘Priority-1 polluted river’. The pollution is exacerbated during rain, when excess water flows and Surface Active Agents reacts with chemicals drained in the river. The NGT has identified the issue and has already registered a case. They have identified untreated water from Bengaluru as the reason and have informed the Karnataka government about ways to prevent pollution.”
In a recent study conducted by the Karnataka government, it was found that Bengaluru city discharges about 1,329 million litres of sewage water. However, the 29 sewage treatment plants (STPs) are only capable of treating 830 million litres. To prevent pollution, over 12 new STP’s have been proposed by the Karnataka government.
The TNPCB has also set up a real-time Water Quality Monitoring Station. Studies conducted between April 2025 and March 2026 revealed that Kelavarapalli Dam had high amounts of ammonia, nitrogen, phosphates, fecal matter and coliform bacteria. As a result, the KRP Dam has also been affected by increased water hyacinth growth.”
The collector informed the Krishnagiri administration and the Pollution Control Board that they are working to clear water hyacinth from KRP Dam. The Tamil Nadu government has also urged the Karnataka government and the Central Pollution Board to find a permanent solution for the foaming issue, the collector stated.