The watershed of the Penna and its tributaries covers part of the southern Deccan plateau, including most of the Rayalaseema region of Andhra Pradesh and part of Karnataka. The Kolar Plateau forms the divide between the Penna watershed and those of the Kaveri, Ponnaiyar, and Palar rivers to the south. The Penna drains the northern portion of the plateau, which includes parts of Kolar and Tumkur districts in Karnataka. The Krishna River and its tributaries drain the Deccan plateau to the west and north of the Penna's watershed, and the low Erramala hills forms the northern divide of the Penna basin. The upper watershed of the Penna includes Cuddapah District, central and eastern Anantapur District, the southern part of Kurnool District, northwestern Chittoor District.