A stone water gauge was found Monday in southwest China's Sichuan Province during dredging and maintenance at the Dujiangyan Dam, a water conservation scheme that dates back 2,250 years.

Li Junzhu, a senior engineer in charge of dam maintenance, said the tablet erected in 1764 was submerged at the bottom of a pool. It was the first time it had seen the light of day for more than 200 years.

According to Li, seven water pumps were used to empty the pool which was more than 10 meters deep.

Standing beneath a steep cliff, the one-meter tablet is thickly dotted with graduations and Arabic numerals which indicate former water levels at the dam.

Judging from these records, the dam's water levels during Qing Dynasty (1644-1911) were lower than in modern times, Li said.

Conservationists also found another relic nearby which might be another water-gauge tablet but as it was severely eroded this has not yet been confirmed.

Built on the upper reaches of a major tributary of the Yangtze River, Dujiangyan is the world's oldest functioning irrigation scheme and is on the World Heritage List of the United Nations Educational, Scientific and Cultural Organization.

The scheme irrigates a land area of 10.09 million mu (about 672,667 hectares) where annual grain output reaches 6 million tons.

To better protect it, a 42-day maintenance program was launched on Oct. 13 which will cost 30 million yuan (about US$3.6 million).

(Xinhua News Agency December 11, 2002)