The water level in the reservoir of China's Three Gorges dam -- the world's largest and most expensive hydroelectric project -- this week reached its capacity of 574 feet, Chinese state media reported.

Cao Guangjing, chairman of the China Three Gorges Corp., told Xinhua news agency that only by reaching the maximum level would all of the project's 26 power-generating units -- each with a capacity of 700,000 kilowatts -- be fully operational.

At peak level, the dam on the Yangtze River would generate an annual output of 84.7 billion kilowatt hours of power.

During the engineered flooding required for the building of the dam, started in 1994 and completed last year, 13 cities, 140 towns and 1,350 villages were submerged and 1.8 million people displaced.

Two previous attempts, in 2008 and 2009, to reach the capacity mark failed. When the dam began to generate power in 2008, the reservoir's water level had reached 567 feet.

But geologists warn that the extra water increases the risk of landslides, earthquakes and damage to the Yangtze River's ecosystem.

Fan Xiao, chief engineer of the Sichuan Geology and Mineral Bureau, told the South China Morning Post that landslides are inevitable because elevated water levels significantly increasing the internal moisture of surrounding banks, making them soft, loose and unpredictable.

"It's like dipping a piece of bread in milk. The deeper you go, the more difficult it is to hold on," Fan said.

The unprecedented mass of water also increases the risk of earthquakes, he said.

Yang Yong, a Sichuan-based geologist, clarifies Fan's warning:, "When the dam reaches 574 feet (the capacity mark achieved Tuesday), it will push the region's geological instability to the fringe of catastrophe."

Three Gorges' revealed its shortcomings when floodwaters raced into the dam's 400-mile-long reservoir in July, prompting a government official to admit that the dam's flood-control capacity "is not unlimited."

Thousands of tons of garbage also accumulated amid the heavy rains, threatening to block the locks of the dam.

When approved in 1992, the dam's original cost was estimated at $8.3 billion. That figure has risen to approximately $27 billion by Beijing's estimate, while other predictions make the final cost at $88 billion.

The project received additional funding Wednesday when China Development Bank announced that it would lend more than $11 billion to China Three Gorges Corp., developer of the dam, over the next five years, Xinhua reports.