The Kariyakoil Reservoir is constructed across Kariyakoil river at the foot of the Kalrayan hills. Kariyakoil river is one of the major tributary of Vasista River also called as upper vellar which confluences into vellar River at Tholudur Regulator. Then the Vellar River drain into Bay of Bengal at Port Nova near Chidambaram in Cuddalore District.
This reservoir benefits Salem District. Athur taluk is benefitted by this reservoir.
The construction of dam was started in the year 1982 and completed in the year 1993.
