Community action/Chennai

Chennai had many lakes spread across the city, but urbanization has led to the shrinkage of water bodies and wetlands. The water bodies have shrunk from an estimated 12.6 km² (4.9 sq mi) in 1893 to 3.2 km² (1.2 sq mi) in 2017. The number of wetlands in the city has decreased from 650 in 1970 to 27 in 2015. Nearly half of the native plant species in the city's wetlands have disappeared with only 25 per cent of the erstwhile area covered with aquatic plants still viable. The major water bodies including the Adyar, Cooum and Kosathaliyar rivers, and the Buckingham canal are heavily polluted with effluents and waste from domestic and commercial sources. The encroachment of urban development on wetlands has hampered the sustainability of water bodies and was a major contributor to the floods in 2015 and 2023 and water scarcity crisis in 2019.

The Chennai River Restoration Trust set up by the government of Tamil Nadu is working on the restoration of the Adyar River. The Environmentalist Foundation of India is a volunteering group working towards wildlife conservation and habitat restoration.

Chennai, also known as Madras, is the capital and largest city of Tamil Nadu, the southernmost state of India. It is located on the Coromandel Coast of the Bay of Bengal. As per the 2011 Indian census, Chennai is the sixth-most-populous city in India and forms the fourth-most-populous urban agglomeration. The city is coterminous with Chennai district, which together with the adjoining suburbs constitutes the Chennai Metropolitan Area, one of the largest metropolitan areas of India. It is administered by the Greater Chennai Corporation, which was incorporated in 1688, and is the second oldest municipal corporation in the world after the City of London Corporation. Being the capital of the state, it houses major government institutions including the Tamil Nadu Legislative Assembly, and the Madras High Court.