Agricultural pollution has made Chao Lake in Anhui province deadly.
The problem is the intense amounts of chemical fertilisers in use.
These leak into the lake and are one of the main causes of poisonous algal blooms.
Unless farmers start using less chemical fertilisers and start practicing eco-agriculture, China's lakes and rivers will continue to be poisoned, yar after year.
Too much fertiliser
The government ran a nationwide program (2005 to 2007) to reduce fertiliser use, but Greenpeace has found that many farmers have in fact increased the amount of chemical fertilisers they use despite this initiative.
We tested the water in Lake Tai last year to see if the pollution problem had eased.
Of the 25 water samples we examined, 20 samples contained such high concentrations of nitrogen and nitrates (found in fertilisers) that they were not safe for human use. They were even too polluted to be used to water crops or in factories.
Farmers around the lake told us they were now using twice as much fertiliser as they were using 10 years ago.
The government-run program tests soil and advises farmers on how much and which kinds of fertiliser they should use.
But this is not a solution to the pollution problem, because it recommends chemical fertilisers rather than ecological solutions.
And it's clearly not reducing the amount of fertiliser being used.
In the three years of national soil testing from 2005 to 2007, the total amount of fertiliser use in China increased by about two million tons every year.
China's water crisis
And it's not just Lake Tai.
All sorts of water systems in China are being polluted this way. In Inner Mongolia in northern China, Lake Wuliangsuhai is plagued by a serious yellow algal bloom and Lake Chao in Anhui province is also poisoned (see slideshow).
While the government has been pouring money into cleaning up Lake Tai, little has been done to solve the root cacuse of the problem.
We want the government to push for a major move from chemical-intensive agriculture to eco-farming.
If this doesn't happen soon, it could be too late to clean up China's precious water resources.
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