Officials in China say the Three Gorges dam is standing up to its biggest flood control test since it was completed last year.
Floodwaters in the giant reservoir rose four metres in 24 hours on Monday and are now only 20 metres below the dam's maximum capacity.
The dam is in Hubei province, on the country's longest river, the Yangtze.
The BBC reports the dam is being used to limit the amount of water flowing further downstream to try to minimise the impact of devastating floods.
The flow of the water on Monday night was the fastest recorded, at 70,000 cubic metres a second.
Cao Guangjing, head of China Three Gorges Corporation, told the BBC that 40,000 cubic metres a second were released, with 30,000 cubic metresa second of water held back in the reservoir.
Beijing cited flood control as a reason for construction of the $US27.2 billion dam. The project forced the relocation of 1.4 million people.