India’s first ever arch dam across two hills was constructed by Sri Ramanujacharya.

Tonnur Lake in the Mandya district of Karnataka is becoming a picnic spot nowadays for many in the surrounding areas, but what people had not known is that this Lake was a product of the efforts of Sri Ramanujacharya, the doyen of Srivaishnavism and proponent of Visishtadvaita philosophy. Many had heard about him and even recognise him for his compassion for all cutting across social barriers. But his contribution to economic prosperity of the region remains unknown. A search into historical records show that he was instrumental in building a dam – an arch dam, across two hills to form what is now called Tonnur Lake.  

During his long stay in Tonnur also known as Tondanur, Ramanujacharya had observed the wasting away of the waters of two mountain streams through a gap between two hillocks. He had thought of an ingenious plan of bridging this gap to store the waters of the streams and make an alternative path to streamline the passage of water in a controlled way for the benefit of the community. He engaged the locals to construct the bund between the two hills that stands at 80 feet height and 500 feet lengthwise.

The Google map shows this bund as a small curve between two long hill ranges. (Picture below)

Ramanuja’s role in the formation of this lake and the bund, now known as Tonnur Kere is absolutely unknown even to Vaishnavite scholars and historians. The proof of his role comes from an unexpected source, the Sthala Purana of Shravana Belagola written by Jains who were bitterly opposed to Ramanuja for getting many Jains change over to Vaishnavism.[i] The Sthala Purana says that the Hoysala king Bitti Deva converted into the Vaishnava religion and under the influence of Ramanujacharya built a tank at Tonnuru (Tondanur) and named it Tirumala Sagara. Surprisingly no inscription of Vishnuvardhana or any Hoysala kings attributes this feat to Vishnuvardhana or any other king. In the absence of any reference to any king or a royal official in the making this engineering feat, the presence of this man-made structure stands as an evidence for a localised and independent effort to build this bund.

The only other evidence of Ramanuja’s role in forming this bund is found in the travelogue of Francis Buchanan published in 1807 soon after Tipu Sultan was defeated by the British.[ii]  On passing through the regions once occupied by Tipu, Buchanan had collected the information on the geography of the land and also the local legends connected with them. His records show that Tonnur Lake was known as “Yadava Nuddi” at that time and was remembered as one created by Ramanujacharya.

His account runs as follows: Read here