Shimsha is a river that flows in Karnataka. It is one of the tributaries of the river Kaveri, which is one of the major rivers of South India. The river originates in the southern part of the Devarayanadurga hill in the Tumkur district of Karnataka and flows for about 221 km (137 mi). before joining the river Kaveri.
Shimshapura Falls is situated in the Shimsha Village of the Malavalli Taluka. The waterfall is the site of the Shimsha Hydroelectric Project, the second hydroelectric power station of Asia. This falls is formed by the Shimsha River that provides water for the project.
Markonahalli Dam is a dam built across the river Shimsha in the Kunigal Taluk of Tumkur district. It was built by Krishnaraja Wodeyar IV, the king of Mysore under the guidance of his Diwan, Sir M Visweswaraiah. It was built to irrigate 6070 hectares of land and has a masonry structure of 139 m and a pair of earth dams extending to 1470 metres on either side. The reservoir has a catchment area of 4,103 km2 (1,584 sq mi) and can hold a volume of 68 million cube m of water at a full reservoir level of 731.57 m above the mean sea level. 27 species of fish, including 13 species of commercial fishes have been recorded in the reservoir with Puntius being the dominant species of fish found here. Cirrhinus reba and Labeo calbasu and other transplanted carps are also found here. However, the maintenance of the dam has been poor. In 2000, a part of the dam had to be demolished to prevent floods and save 25 villages. Water started overflowing the dam and only 1 crest gate could be opened. Nearly 150 feet of the dam was demolished to allow excess water to flow out.