White Papers
Water Quality Concerns in Shanghai
In early July 2007 floodwaters sluiced from nearby rivers introduced pollutants into Shanghai's water resources. Zccording to the Shanghai Water Authority tap water in the city remained safe. At the time they said that the high content of harmful substances - ammonia, azote and nitrite - that had been detected at the intake spots of Shanghai's two reservoirs on the Yangtze and Huangpu rivers. They reiterated that the city's drinking water remained safe due to carefully choosing the intake times from the reservoirs and increased levels of water sanitation.
The flood season problems were not the only concern as outbreaks of blue-green algae in Taihu Lake is another reason that the Shanghai water authority has said it has been closely monitoring the water quality. The growth of algae shut down the city of Wuxi's drinking water supply for a week following the continuous downpours, which started in June 2007, had brought floods, landslides and death to several provinces. For example Liuhe River in Jiangsu Province, with floodwater from Taihu Lake and other water channels from Suzhou, poured large amounts of polluted water into the part of Yangtze River near Shanghai. Although the city draw most water from the Huangpu river the whole water catchment area remained affected. A sampling in June 2007 at the intake spot of Chenhang Reservoir, which is 4 km from the Liuhe and Yangtze rivers, found the ammonia and azote content more than 20 times higher than usual but still within acceptable standards. The Chenhang Reservoir contributes one-third of Shanghai's water supply.
The other reservoir in the upper reaches of Huangpu River, also connected to Taihu Lake, was also found to have nitrite higher than standard at its intake spot. The nitrate is mainly from agricultural and industrial waste dumped in nearby rivers, according to an expert quoted by Shanghai Morning Post.
To safeguard Shanghai's tap water, city water companies have adjusted their intake hours to avoid low tide, when pollution is comparatively higher. They have also extended the chemical precipitation period and added chemicals when necessary.
Source: China Daily 12 July 2007
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