Dian Lake or Kunming Lake is a large inter-land lake located on the Yunnan-Guizhou Plateau close to Kunming, Yunnan, China. Its nickname is "Sparkling Pearl Embedded in a Highland," and it was the model for the Kunming Lake in the Summer Palace in Beijing.
It is a freshwater fault lake at 1,886.5 m (6,189 ft) above sea level. The lake covers 298 km2 (115 sq mi). It is 39 km (24 mi) long from north to south, and the average depth is 4.4 m (14 ft). It is the eighth largest lake in China and the largest in Yunnan Province.
Pollution is a major problem for the lake. In the city of Kunming, the capital of subtropical Yunnan province, there is no talk of drought, since the city is right next to one of Asia's biggest freshwater lakes. But until the first wastewater plant was built in 1990, 90 percent of Kunming's wastewater was pumped untreated into the lake. The lake water is now undrinkable despite several billion United States dollars having been spent trying to clean it up. Some experts predict that over 55% of the lake's fish population has been killed off by this disease ridden type of pollution.The water in the lake is rated Grade V (the worst grade) which makes the water unfit for agricultural or industrial uses.