The Cauvery River in Tamil Nadu is facing serious pollution. Untreated sewage, industrial waste, agricultural runoff, and pharmaceutical residues flow into the river. Many of its tributaries now act like drains. At Mettur Dam, industrial effluents are said to be dumped at night when water releases dilute them. Farmers see dead fish daily, blaming pollution. Officials deny discharge but admit sewage treatment plants exist. In Erode, over 500 dyeing, bleaching, and tannery units release waste into streams feeding the Cauvery. Only a fraction of the city’s sewage is treated. The Central Pollution Control Board labeled this river stretch polluted in 2022. Downstream in Namakkal, dyeing factories illegally pump Cauvery water and dump untreated waste back into the river. Residents avoid municipal water due to cancer fears. Although Karur dyeing units installed zero liquid discharge systems, domestic sewage still pollutes. Encroachments on river buffer zones let waste flow into the water. In temple town Kumbakonam, waterbodies act as waste dumps. Irrigation canals in Tiruvarur are so polluted they no longer support farming. Sewage and waste mix with irrigation water, causing health issues like skin problems. The polluted river also carries pharmaceutical chemicals and heavy metals that standard filters miss. This contamination makes soil hard and reduces crop yields, especially in the Nagapattinam delta. Sand mining worsens the river’s self-cleaning ability. The Tamil Nadu government has launched plans to improve sewage treatment, build new facilities, and remove waste from riverbanks. Environment Minister Thangam Thennarasu said funds were requested to stop pollution and install treatment plants in industrial areas. Efforts aim to save the Cauvery, which supports millions of farmers and residents but currently suffers heavy environmental damage.