CARACAS (Reuters) – The Guri dam, which supplies more than half of Venezuela’s electricity, may have to halt a large part of its generation by mid-May if a drought persists, the president of the utility Edelca said on Thursday.

Venezuelan officials have said Guri — one of the world’s largest hydroelectric dams with an installed capacity of more than 10 gigawatts — would have to slash its output by at least half if its reservoir falls to the so-called critical point where water cannot feed some of its turbines.

“It’s possible that if there is a continuing extreme drought, we could get to a critical point by mid-May,” Igor Gavidia, president of state-run Edelca, told state television. “This would require shutting off part of Guri.”

President Hugo Chavez, whose leftist government has rationed power and water in much of Venezuela due to the prolonged drought, had said that Guri’s reservoir was not expected to reach a critical point until June at the earliest.

Power shortages threaten the OPEC member’s oil-driven economy after it shrank 3.3 percent last year.

Reservoirs that supply Venezuela’s main hydroelectric dams have fallen to a third or less of normal operational levels.

Guri would cut output if its reservoir levels fall to 240 metres (262 yards) from around 253 metres now. The reservoir is at least 18 metres below normal for this time of year and has been falling more than 15 cm (6 inches) per day, Gavidia said.

Venezuela is likely to avoid major blackouts or deeper rationing, he said, because of seasonal rains usually starting in May that replenish reservoirs, the existing electricity rationing and new thermal power plants.

“We do not think there will be chaos,” Gavidia said. “We think the possibility is a remote one.”

But he said the capital Caracas has cut its power use by only around 2 percent since the government introduced measures that include heavy fines on consumers who do not conserve. He said Caracas is expected to reduce its consumption by 10 percent in coming months.

The strict power-saving measures imposed last month should remain in place “from now on” to help Venezuela cut electricity use in the long term, Gavidia said.