HARIPUR, Dec 14: The decreasing water inflow in the Tarbela Lake has reduced power generation at the Tarbela dam to almost one third of its original capacity, official sources said on Friday.

The sources told Dawn that the chilly weather in catchment areas of the Tarbela Lake had affected the flow of water.

The reduced quantity of water in the lake has brought down the power generation capacity to 1,168 megawatts from its rated capacity of 3,478 megawatts, the sources said.

Tarbela dam, the biggest hydel power source of the country, contributes about 60 per cent of the total hydel power generating system.

With the start of the snow-melting process in July every year, the rated capacity of the dam increases to a level of 3,700 megawatts as the Tarbela Lake receives enhanced quantity of water, measuring about 170,000 cusecs.

According to statistics recorded on Friday morning, the total inflow was 17,300 cusecs and outflow was 25,000 cusecs while the level stood at 1435.35-feet against the maximum conservation level of 1,550-feet.

Tarbela Lake, the biggest artificial lake of the country, is spread over an area of 265 square kilometres. The length of the reservoir is 97 kilometres and the maximum depth is 450-feet, 1,100-feet above the sea level.

Meanwhile, official sources at the power house said that the power generating unit No 4 of the Tarbela Power House had been shut for annual maintenance on Friday. The unit, according to the sources, would remain closed for thirty days.