Once the waters are used for the generation of electricity, the oil deposits flow into the Kelani river.
The Central Environmental Authority has taken no action despite being informed.
There is suspicion that oily effluent is secretly channeled by factories into the canals and other water bodies linked with the reservoir, including Keselgamu Oya and Dickoya canal.
There are several tea factories located in the vicinity.
These oily effluents could also threaten the inland fish that had been released in large numbers by the National Aquaculture Development Authority into the reservoir.