This Rs. 350 million project will have an adverse impact on the biodiversity in the Pelen Ganga and Peelithudu Falls, the Trust says in a statement.
The aim of the project is said to be to generate 1.5 megawatts of power and to earn a daily income of Rs. 436,000, it says.
It plans to build a dam across Pelen Ganga above the Athweltota Falls to divert the waters, via a reservoir to plant one kilometer downstream.
This will cause flooding of the areas above the location, while a shortage of water could be experienced in the lower area, the Trust warns.
Furthermore, the aquatic plant, fish, crab and snail species in the Pelen Ganga will face extinction, the statement adds.