Qingcaosha, a reservoir that uses water from the Yangtze River, will start water supply before May 1 of next year when the metropolis hosts the Shanghai World Expo, a local environmental official pledged yesterday.

Zhang Quan, director of the Shanghai Environmental Protection Bureau, said construction on the reservoir dam was completed late last year,.

He said the new reservoir will help ensure safe drinking water for the 18 million residents of Shanghai once it becomes operational next year.

"By then, around 70 to 80 percent of the overall population in Shanghai will get access to the better-quality drinking water from the Yangtze River," said Zhang yesterday in an online chat at local portal eastdays.com.

Qingcaosha, located near the Chongming Island at the mouth of the Yangtze River, will be able to store 435 million cubic meters of water and provide more than half of the city's water needs with an estimated daily supply of 7.2 million cubic meters.

The reservoir, with an investment of 17 billion yuan, will be the third major water source for Shanghai, aside from the one located at the upper reaches of the Huangpu River, which now contributes 80 percent of Shanghai's water, and Chenhang reservoir, which contributes the rest.

Shanghai, with abundant water resources due to its location at the mouth of the Yangtze River, has long been plagued by poor water quality, featuring a high emission rate of ammonia and nitrogen arising from heavy industrial pollution at the upper reach of the Huangpu River.

The salt tides, which mostly occur from November until April during the low-flow season of the Yangtze River, make matters worse.

The Shanghai Water Affairs Bureau said on Tuesday that a third wave of salt tide is hitting the Chenhang reservoir, forcing the water agency to reduce the daily water supply from the Yangtze to 1.3 million cubic meters from the previous 1.6 million.

To tackle the drinking-water problems, the city's environmental administration launched three rounds of Three-Year Environmental Protection Action Plan between 2000 and 2008, continuously improving the city's sewage water treatment and water quality in downtown river lanes.

The city has 50 sewage water treatment plants in operation, with overall daily water treatment capability reaching 6.7 million cubic meters, ranking first among all cities in China.

He said the environmental watchdog will make more efforts this year to improve water quality and garbage handling capacity, and to cut down on noise in urban areas.

He added that the city is considering an upgrade to its 800-odd gas stations in the next two years to realize oil and gas recovery and reduce pollution.

(China Daily February 19, 2009)