In a disturbing sight, several fishes were found lying dead on the banks of river Tunga in Matturu-Hosahalli village on Wednesday.
After the incident, villagers are reportedly afraid of using the river water for drinking and other purposes.
"Since the last five or six days, the colour of the river water has turned green and fishes in it have been dying. The local populace in villages use the river water for drinking but people are now afraid to do so," said Bhanu Prakash, a villager.
Villagers said that officials visited the site and took samples of fishes and the water to be tested.
"Officials were informed; they came and took samples of water and fishes for forensic examination. They have assured us that all proper measures would be taken and all possible help would be delivered," a villager said.
Tunga river originates in the Western Ghats and provides clean drinking water to many cities including Shivamoga.
Along the bank many villages use the same water for irrigation as well. It joins Bhadra river and flows further to middle Karnataka. It feeds thousands of hectares of land and provides drinking water to lakhs of people.