The South Pennar River (also known as Dakshina Painakini in Kannada and Thenpennai or Ponnaiyar or Pennaiyar in Tamil) is a river in India. It is the second longest river in Tamil Nadu, with a length of 497Â km, after the Kaveri. Chandapura, Anekal, Hosur, Bagalur and Chengam are the major industrial settlements on its banks. The river is severely polluted by industrial waste as it flows through major industrial areas in the eastern suburbs of Bangalore and the industrial parks of Hosur and Chengam.
The river originates in the Nandi Hills in the Chikkaballapura district of Karnataka and flows through Tamil Nadu before emptying into the Bay of Bengal. It has a catchment area of 1,424 square miles (3,690Â km) located in Karnataka and Tamil Nadu states. The small Kelavarapalli and Krishnagiri Dams were built across this river near Hosur and Krishnagiri. The largest dam on this river, Sathanur Dam with 7.3 Tmcft Gross Capacity is near Tiruvannamalai. The Moongilthuraipattu Sugar Factory is also situated on the bank of river.