Penna (originally known as Penneru, also known as Pinakini, Penneru, Penner, Pennar, Pennai) is a river of southern India. After originating from Nandi hills, it flows as two different streams, one in North and South directions. The Penna rises in the Nandi Hills in Chikkaballapur District of Karnataka state, and runs north and east through the states of Karnataka and Andhra Pradesh to empty into bay of bengal in Andhra Pradesh. It is 597 kilometres (371Â mi) long, with a drainage basin covering 55,213Â km: 6,937Â km in Karnataka and 48,276Â km in Andhra Pradesh. Along with this main stream is another stream south towards Tamil Nadu with the name Then Pennai or south Pennar which further moves towards the east to empty into the Bay of Bengal. The Penna river basin lies in the rain shadow region of Eastern Ghats and receives 500Â mm average rainfall annually.