Nuoc Trong Reservoir in Son Ha Commune has a designed capacity of nearly 290 million cubic metres, supplying irrigation water and feeding the Nuoc Trong hydropower plant.
Despite the rainy season, its water level stands at just over 117 metres, 12 metres below the normal operating level.
According to Vo Nhat Sy, head of Irrigation Management Unit No. 2 at Quang Ngai Irrigation Works Management Company, the reservoir played a vital role in supplying water to more than 50,000 hectares of farmland downstream of the Tra Khuc River.
He said El Nino had sharply reduced rainfall compared with previous years, leaving inflows into the reservoir exceptionally low.
"Water levels at Nuoc Trong have fallen to just 58 per cent of capacity due to sharply reduced rainfall," Sy said.
"We must conserve water and prepare rotational irrigation schedules from the coming winter-spring crop to ensure sufficient supplies throughout 2027."
The province's 23 other reservoirs in the eastern region are holding only 54 per cent of their combined designed capacity. Nui Ngang Reservoir is at nearly 35 per cent, An Tho at 34 per cent and Liet Son at just over 25 per cent.
Nguyen Thanh Hung, deputy director of Quang Ngai Irrigation Works Management Company, said the company had requested the Nuoc Trong and Nui Ngang hydropower plants to suspend electricity generation from November 3 to conserve water.
Under the plan, the plants will resume generation on December 5, when water releases for the winter-spring crop begin.
Alongside hydropower restrictions, irrigation authorities are preparing water distribution plans for adverse conditions.
The company has instructed its units to develop measures against natural disasters, drought and saltwater intrusion, and to introduce rotational irrigation from the winter-spring crop.
Three major hydropower plants in eastern Quang Ngai, including Nui Ngang, Nuoc Trong and Dakdrin, have now suspended electricity generation to conserve water.
Dakdrinh, whose reservoir has a designed capacity of 248 million cubic metres, stopped generating power on November 1.
Nguyen Duy Nghia, head of the technical department at Dakdrinh Hydropower Joint Stock Company, said the plant's main function was electricity generation, with an assigned average annual output of 540 million kWh.
The company had complied with instructions from the Ministry of Agriculture and Environment and the provincial authorities to suspend generation and help secure water supplies for agricultural production in 2027.
"We have stopped generating electricity and aim to raise the reservoir level to 410 metres by the end of December," Nghia said.
"That is the normal operating level under the design, allowing us to generate electricity while securing water supplies for agricultural production in 2027."
Amid concerns over water shortages next year, the chairman of the Quang Ngai Provincial People's Committee issued instructions on November 4 to prevent and minimise drought damage.
Concerned agencies were ordered to closely monitor weather conditions, assess reservoir water levels and prepare response plans for various scenarios, including conditions worse than forecast.
