Unidentified miscreants mixed a green coloured chemical in Koottaatru river near Udumalpet in Tirupur district on Thursday.
Local activists and residents claim that the sand mining mafia might be the culprit.
Koottaatru is a small river in Ravanapuram, near Udumalpet. Pallaru and Nalaru are the two rivers that join Kootaatru river.
The river water is supplied as drinking water to residents of Devanaurpudur, Ravanapuram and Chellampalyam.
On Thursday morning the residents found the water had turned green and was smelly and they complained to the panchayat and district administration.
“The sand mafia group has been restricted in this area. Hence, to threaten the people and the district administration, members of the mafia have resorted to such a heinous action.
The green coloured chemical mixed in the river is a pesticide, used in the agricultural fields,” said Suresh, a resident of Ravanapuram.
“With the help of the fire service personnel, we have started pumping out the chemical-mixed water.
We have also taken samples of the chemical and sent it for laboratory test,” said district collector M. Madhivanan here on Friday. The Udumalpet police has registered a case and is investigating.