Both rivers flow in a westerly direction south of the Adams Peak hill range, on the southwestern slopes of Sri Lanka.

The catchment basin of the source, especially the Bambarabatu Oya sub-catchment, experiences some of the highest and most consistent rainfall in Sri Lanka.

The project comprises a diversion weir, intake, headrace channel, forebay, penstocks, powerhouse, tailrace, and switchyard.

The intake structure is on the right bank of the river and the waterway continues for 1,800 meters in a channel with a box section up to the forebay tank.

The site is reached by turning right just beyond the Malwala town and proceeding approximately 3 km on a by-road The project developer is Country Energy (Pvt) Ltd, a subsidiary of Vallibel Power Erathna PLC,[2] which is one of the leading mini hydropower developers in Sri Lanka.

Parallel to that, bungalow, batching plant, crusher, bulk material store yards, stores, working yards, site office and labour camps were properly structured and everything was managed in a good professional manner.

[1] The intake leads to the rectangular profiled headrace channel of 1,800 m length which was made of reinforced concrete.

The headrace channel lies on the right bank of the stream and it has 4.4m inner width and 2.2m of wall height while the design flow is 27m3/s.

The pipe was spiral welded steel made to American Petroleum Institute standards (API 5L Grade B).

The power generation units are manufactured by Dong Feng Electric Machinery Works Co., Ltd (China)[2] and have a total capacity of 7.2 MW.

More details on the applied technology are as follows, The tailrace channel conveys the tailwater back to the river.

A single circuit concrete pole line was built along the road from the powerhouse to the feeder.

Jayawardhana, and Aruna Dheerasinghe and powerhouse hydraulic designers were Dong Feng Electric Machinery Works Co., Ltd The plant is commissioned in February 2012 and since then it serves Sri Lankan national grid by providing 25GWh of green energy in every year.

The project reduces approximately 13,500 tCO2e of annually as a result of displacement of fossil-fuel based grid electricity in Sri Lanka.

During the operation and construction period, the project created new training opportunities for the local community members.

In addition, the general public at large including the local residents and communities indirectly benefited from the greater availability of clean electricity in the national grid which would otherwise be met through grid-connected fossil fuel-based power plants.

The potential environmental impacts identified were soil erosion, loss of soil stability and slope failure, reduction in the river flow between the weir and tailrace, and some ecological impacts such as interference with fish mobility, destruction of plants and noise.

[8][4][7] Confirming that the Denawaka Ganga MHP is an environmental friendly project, UNFCCC (United Nations Framework Convention on Climate Change) registered it as a Clean Development Mechanism (CDM) project[11] CDM project consultant was Mitsubishi UFJ Morgan Stanley Securities Co., Ltd and coordination work from Country Energy (Pvt) Ltd was done by chief executive officer; Aruna Dheerasinghe and Engineer; Tharanga Baduge.