Guwahati, Oct. 26: If the siltation-induced water crisis of the Brahmaputra last winter was Guwahati Refinery's worst since its inception, the situation this year is even more precarious with the water having reduced to below 1,000 cubic metres per hour at Soonsali ghat.

Refinery sources say the water level of the Brahmaputra has gone down substantially since August. According to records, the water level in the area was 168.7 feet above mean sea level in July as against 149 feet today.

A 1.5km sandbar has cut off water from the main course to the intake point, prompting the Indian Oil Corporation-owned refinery to extensively (about 12 hours a day) use a dredger to clear silt.

Siltation started this year from August, compared to October last year. Water from the river is drawn in through two barges. Four of the eight suction pumps linked to the barges are operational.

A depth of six to 14 feet is being maintained right now through dredging in the suction area for drawing water.

"A dredger hired from a Chennai-based firm is under operation now. Our dredger is being repaired and will take about a week to be operational. We have also placed an order for another dredger from a Goa-based company, which should be available for use by June next year," the refinery's executive director Jogen Borpujari told this correspondent.

The danger, though, is that the dredger in use right now has to be kept operational till the other is repaired.

Officials at the intake point say once the old dredger is repaired, they will use both simultaneously - one will keep a channel fed from the Kharguli side (western) of the river active while the other will be operated 500 metres away from the barge to clear silt and make water available from the river's mainstream in the east.

At least 60 to 70 per cent of the water from the intake point is used for non-refinery purposes such as supply of drinking water to the township in Noonmati and entities such as Military Engineering Services and Oil India Limited, Narengi. The rest is used for refinery operations.

Last winter, water availability at the intake point had reduced from 1,300 cubic metres per hour to about 1,000 cubic metres per hour because of siltation, prompting the refinery to ration drinking water.

The refinery, the oldest in the country, had then used its 50-year-old dredger. The water is sourced from the surface of the river and treated in the refinery's plant.

About 400 cubic metres of water drawn in every hour is for community development supply. "We may, like last year, consider a curtailment of supply to residents of Noonmati living outside the township as well," Borpujari said.

The refinery has a capacity of one million metric tonnes per annum and processes crude from the oil fields of Upper Assam. It caters to the Northeast with products comprising liquefied petroleum gas, motor spirit (petrol), aviation turbine fuel, kerosene, high-speed diesel, light diesel oil and raw petroleum coke.

Navigation-wise, too, the situation is precarious with instances of vessels getting stuck in shallow water during winter. The Inland Waterways Authority of India here carries out dredging to clear silt from navigation channels during winter. However, sources say they have only two dredgers at their disposal, far from adequate for the 891km river. In August, the Assam government had announced that it would dredge the Brahmaputra and sought help from the Dredging Corporation of India Limited.