Since May there have been very frequent water pollution incidents in China’s rivers and lakes; and they have all been closely followed by good news about the release of clean water to improve the situation. First Taihu Lake started to stink and the nearby city of Wuxi had its water supply rudely interrupted. At that time, the Ministry of Water Resources promptly ordered hundreds of millions of tonnes of clean water from the Yangtze River to be diverted into the lake, resulting in a rapid improvement in water quality.
Then east China's Chao Lake was overwhelmed by a tide of blue-green algae in June. Just as worries started to emerge, the water bosses opened the valves - and sent more Yangtze River water rushing down hundreds of kilometres of waterways. Three days later we were informed that the water in the eastern half of the lake had been effectively replaced with water from the Yangtze River, and that water quality was showing a clear improvement.
While it is gratifying to see the algae retreat and water quality improve, we should be concerned by the fact we rely on diverting water to solve these crises.
First of all, this is not treating the root of the problem. Although the increased flow can purify the water supply, all it really does is dilute the pollutants. Like flushing a toilet, it moves the problem, it doesn’t actually get rid of it. The pollutants are still present, they have just been swept downstream. Unless properly treated, all these pollutants will do is reduce water quality somewhere else.
This will not worry some, "just get it out of my river," they say. But while the extra water will reduce the amount of pollutants in the short term, if money is not spent on reducing the impacts of industry, agriculture and local populations, pollution will continue to flow into the waterways. The pollutants will remain in the water, or lie in the silt, and similar problems will arise again as soon as the conditions are right – triggering yet another water crisis.
Xinqiang River, the source of drinking water for the city of Yueyang in central China's Hunan province, became contaminated with arsenic in September last year. The local government, as ever, poured in water from further up the river to dilute the problem. But two days later, the levels of arsenic remained as high as ever. Further investigation found that the arsenic had been building up in the river bed for years – the extra water had merely set it free.
Water transfers just move the problem along – and water quality also suffers in the areas where the water originates. Water quality in the Yellow River has been falling constantly in recent years due to the increasing amount of pollution dumped in the river – but also due to the amount of clean water that is taken out. The Yangtze River is a much larger river than the Yellow River, but it still has its limits. According to the Yangtze River Basin Water Resources Report, 41% of all of China’s waste water ended up in the Yangtze River in 2004. The number of stretches of the river classed as polluted rose by 5% in that year. With plans to divert water from the Yangtze River to the north underway, and increased removal of water to deal with pollution incidents, the situation can only get worse.
We also cannot overlook the environmental and social costs of water management projects themselves. Yunnan has been working on plans to dam Tiger Leaping Gorge and excavate a 400 kilometre canal to bring 2.5 billion tonnes of water to Kunming and other cities every year. It will also relieve pollution in some of the province’s lakes. But this will require the relocation of almost 100,000 locals and the loss of irreplaceable natural scenery and cultural heritage.
Diverting water can work to relieve a crisis, but it will not stop the next one. If our cities continue to treat rivers as sewers, our rivers may one day become little more than cesspools. We must focus our efforts on controlling the sources of pollution – and on dealing with the source of the problem.
Ma Jun is the director of Institute of Public and Environmental Affairs
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