The Vaigai River is a major, semi-perennial river in the state of Tamil Nadu, India, flowing approximately 258 km before emptying into the Palk Strait near the Pamban Bridge in Ramanathapuram district. It is a geographical feature, originating in the Varusanadu Hills on the Periyar Plateau in the Western Ghats. Historically, the Vaigai is deeply connected to the ancient Pandya kingdom and is revered in Sangam literature dating back to 300 BCE. The river is the lifeline of the city of Madurai, which is situated on its banks, and is central to cultural events like the annual Chithirai festival.
The river's mechanism for water supply is complex, as it receives a significant feed from the Periyar Dam in Kerala, with water diverted via a tunnel through the Western Ghats into the Vaigai basin. The Vaigai Dam, built in 1959 near Andipatti in Theni district, is a crucial structure that provides water for irrigation to districts like Madurai and Dindigul, and meets the drinking water needs of five districts: Theni, Dindigul, Madurai, Sivagangai, and Ramanathapuram. Key tributaries include the Suruliyaru, Mullaiyaru, and Manjalaru.
Recently, the river has been the subject of significant environmental intervention due to severe pollution from untreated sewage and industrial waste. The Madras High Court has directed local bodies to prepare an actionable timeline for its rejuvenation. This connects to ongoing efforts like the Vaigai Riverfront Development Project and the expansion of the Underground Sewerage Scheme (UGSS) under the AMRUT 2.0 programme, which aims to prevent sewage discharge. Despite these initiatives, the river's downstream stretch in Madurai recorded a high Biological Oxygen Demand (BOD) level of 7 mg/L in 2024, indicating heavy pollution and placing it under Priority IV for intervention by the Central Pollution Control Board (CPCB).