Protecting Dianchi Lake: Kunming is on the mission

Wetland in Dianchi Lake, southwest China's Yunnan Province. [Photo: Imagine China]

Through the years, pollution on the Dianchi Lake, a large reservoir in southwest China's Yunnan's capital, Kunming, has created significant environmental problems, something the local government has been taking steps to try to clean up.

In the city of Kunming, parts of which are subtropical, there is traditionally no concerns over water shortages, as the city is right next to Dianchi Lake, one of Asia's largest freshwater lakes lying close to the Yangtze River.

However since the 1990s, the water quality of the lake has been on the decline amid the rapid pace of urban development of Kunming, with pollution from industrial activities and agricultural runoff being the major problems.

The water in the lake is rated Grade Five, the worst grade in China, which makes the water unfit for even agricultural or industrial use.

Deputy mayor of Kunming, Wu Tao, says the local government has changed its priorities in recent years to restore the ecology of Dianchi Lake, given that the efforts made in the past to clean up the lake have shown little effect.

"In the 1990s and early 2000s, we used to tackle the problems case by case. Now we changed the method into a more systematic way. We monitor the whole 2000 square kilometer area which Dianchi Lake water covers and control the water pollution considering the whole picture. We have initiated six major projects, for example a 57-hundred kilometer long fence alongside the lake to keep out polluting materials, turning 675,000 hectares farmland into forestry or wetland," says Wu.

In addition, government is now implementing its river chief system, meaning all 35 rivers that flow into Dianchi Lake are under more intense inspections.

Pollutants inside the lake are being constantly removed.

To do this, authorities have linked a man-made canal with Dianchi Lake to help bring in fresh water to help flush the lake out.

Many ecosystems have also been restored along the lake to prevent land run-off.

The Laoyuhe Wetland is a typical example of how the eco-environment can purify the water that flows into the lake.

"We took down the dam that used to separate the lake shore and the water, so that a more natural water line will take into shape. In 2009 we also introduced a special cedar tree that can live in water. In this way a wetland full of trees were built and thus the function of purifying water can be further enhanced," says Tu Shuang, the head of the Laoyuhe wetland project.

In the 1990s, nearly 90% of Kunming's wastewater was pumped untreated into Dianchi Lake.

After realizing the damage that was causing, local authorities have since commissioned a dozen wastewater treatment plants to help keep Dianchi Lake clean.

"Kunming is within the Dianchi Lake eco-region. Our work is to recycle the water and discharge it to nearby places for industrial use. Eventually the water will go into a branch of the Yangtze River. Therefor the aim of our work is to improve the quality of the water we let out. This is very important for the utilization of the recycled water and ecological protection when it enters into natural water reservoirs," says Wan Taiyin, the deputy manager of Kunming number-7 wastewater factory.

Authorities in Kunming have laid out a goal to improve the water rating on Dianchi Lake to grade four by 2020.