In 1991 inflows had been a little over 1775GWh up to September with the full year bringing 2874 GWh equivalent of water.
Inflows have hit a record low despite the addition of new hydro plants in to the system such as Kukule River and Upper Kotmale since 1991.
In 2011, which was also a drought year, inflows to hydro plants and reservoirs were 3,565 GWh.
Three monsoon rain seasons have now failed in a row.
Sri Lanka's drought began to hit from the second quarter of 2011. In 2010 when Sri Lanka received unusual levels of rain triggering record floods, reservoirs had received 5,125 GWh of rain.
"The lack of rain can result in an abnormal situation in the electricity system," the power ministry said in a statement, without specifically warning of power cuts.
The statement quoted urged the public to save energy by switching off unnecessary lights which would conserve power and allow the CEB to avoid power cuts.
"We are not cutting power like in India," the minister was quoted as saying. "That is why we are asking to use power carefully."
This year Sri Lanka cut power for the first time in 10 years, after a newly built Chinese build coal plant failed on top of weak rainfall.
Without the coal plant however Sri Lanka would be in greater difficulties, and liquid thermal generation is about four times as expensive as coal.
The problems in Sri Lanka's energy sector come mainly from rulers subsidizing power especially to retail users, places of religious worship and also to industry.
A tariff plan in 2011 also charged less from state schools and hospitals, with state-run power utility Ceylon Electricity Board taking on part of what should have been in the education and health budgets.
Over the past year credit taken to manipulate energy prices drove Sri Lanka into a balance of payments crisis, sending the rupee plunging from 110 to 134 rupees to the US dollar driving up inflation over 9.0 percent a year and destroying lifetime savings of people.
Though energy prices were raised in February 2012 to help fix the balance of payments crisis, energy sector officials say, state-run Ceylon Petroleum Corporation is losing money on heavy fuel oil sales to the CEB.
Petrol is heavily taxed and sold at a profit. Diesel is taxed and sold at a loss. Lanka IOC, a unit of Indian Oil Corporation, raised diesel prices by four rupees a litre last week saying it had lost 350 million on the fuel.