A stone inscription records that a group of Brahmins had asked permission from one of the Kongu Chola kings to build a dam across the river Noyyal.
River Noyyal, which has almost become a stream carrying industrial effluents, was once brimming with crystal clear water irrigating plenty of agricultural lands around Coimbatore.
With an excellent irrigation system, the river conveyed water to the tanks through its various canals and there used to be abundant water in those tanks even during the dry days of summer. But, now, with the key waterways of the river being blocked by residential areas, the river lies as a stagnant pool of drain.
As inscribed in many copper plates, there were once a total of 32 check dams built across the fast-flowing Noyyal river and irrigation was directly under the control of the king. An epigraph dating back 12th century AD mentions two dams built across the Noyyal near Perur.
The inscription on the epigraph records that a group of Brahmins had asked permission from one of the Kongu Chola kings to build a dam across the Noyyal river and to construct a village for them naming it as 'Puhalidam Kodutha Chola Sathurvedi Mangalam “As requested by the Brahmins, the king also granted permission for building the dam and ordered the Brahmins to name it 'Devi Sirai' As there was already a dam across the Noyyal by the name 'Konur Anai' the king had ordered the Brahmins to convey water to the reservoir Devi Sirai only after the Konur Anai filled to the brim. Also, another epigraph discovered at Sarkar Periyapalayam mentions king Sundarapandiyan's appointment of a pearl fisherman called Pillayan from Vellalore to maintain the water bodies at Sulur. 'Pathittru Pathu' a Sangam Anthology of verse, notes that the people of Kongunadu dug wells as sources of water for their cattle.
With Coimbatore situated at the foot of the Western Ghats, there was abundant rain and the rivers in the district were flowing. Of all the kings who ruled Kongunadu, the Kongu Cholas and Veerakeralars were famous for constructing canals at the rivers Amarawathi, Noyyal and Aliyar. While the epigraphs discovered at Perur and Boluvampatti mention the canals carrying water from the Noyyal river, the ones discovered at places like Cholamandalam and Kumaralingam record the names of the canals carrying water from Amarawathi.
Following them, after the 14th century AD the Wodeyars of Mysore built many lakes and ponds at Avinashi, Pazhangarai, Perur, Chevur, Annur, Sarkar Samakulam, Thirumurugan Poondi and Perumanallur. Since many of the canals were named after the kings and queens of Kongunadu, historians assume that those canals were built directly under the supervision of kings.