The surface area of China's largest freshwater lake, Poyang Lake, in east China's Jiangxi Province, has almost quadrupled to 2,370 square km in less than a month due to persistent heavy rainfall, according to new figures released on Wednesday.

Local authorities reassured the public that the risk of flooding from the body of water remains low, and noted the phenomenon is good news for wildlife.

Poyang Lake's surface water was only 668 square km on April 11 but had risen to 2,370 square km by 8 a.m. on Wednesday, and it is expected to increase even more, said Tan Guoliang, head of the Jiangxi Provincial Hydrology Bureau.

Its water volume has also increased from 1.14 billion to 5.85 billion cubic meters between April 11 and May 2, Tan added.

Both the surface water and the volume are expected to continue to increase as the lake has a net inflow of 5,000 cubic meters of water per second.

Statistics show Jiangxi has witnessed an average rainfall of 765 mm between January and April, 35 percent higher than normal for the period, and rains are more frequent and heavier after April.

The flood risk is still low and more water in the lake can provide a better living environment and more food for fish living in Poyang Lake, including threatened finless porpoises, Tan said.

Since the beginning of this year, more than 20 of these animals have been found dead in the Yangtze River and two lakes including Poyang Lake. Initial autopsies showed that most of them died of starvation.

Poyang Lake, with 300 to 500 finless porpoises, or one-third of the country's total, has reported the deaths of six porpoises this year.