The last time GoKunming wrote about the long-running multi-billion yuan effort to clean up Kunming's Dianchi Lake, the city had just embarked on an unlikely pilot project to use an invasive plant species to absorb pollutants and reverse the lake's eutrophication.

Now officials have announced that they will soon test another seemingly fantastical cleanup method: Japanese ozone generators.

The Chinese and Yunnanese Development and Reform Commissions and Japan's state-funded New Energy and Industrial Technology Development Organization agreed on May 7 to use Dianchi as a demonstration site for ozone lake treatment technology developed in Japan. Media reports made no mention of the scale of the project, its cost, or how it would be funded.

The pilot program will use ozone generators and circulate ozone and oxygen through Dianchi's water. Ozone is a strong oxidizing agent and officials hope that it will break down pollutants, including toxins and the nutrients that allow algae and other plants to choke the lake and rob it of the sunlight and oxygen it needs to maintain a balanced ecology.

But ozone, which is generated by exposing oxygen to an electrical current, is expensive to produce in large quantities. Furthermore, Dianchi is China's eighth-largest lake and it is unclear how many generating stations would be necessary to have a meaningful effect on its health.

A better bet for Dianchi might be a comprehensive strategy to control residential, industrial, and agricultural runoff in the lake's catchment area. On this front, Kunming does seem to have made some progress recently in forcing companies to deal properly with their wastewater.

But rehabilitating Dianchi remains a Herculean task. The lake has acted as a massive wastewater dump for decades as Kunming grew and industrialized into its present state – and it still has a water quality classification hovering around five, almost the worst possible grade.

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