A lakefront hotel in Dali stands empty after being closed by the government as part of efforts to improve the water quality in Erhai Lake.Hou Liqiang / China Daily

In addition, until work on a new sewage network around Erhai Lake is completed in June next year, businesses will be required to pay to regularly transport their wastewater to one of seven nearby treatment plants.

This will also hit owners in the pocket. Dali Aotuo Sewage Transport Co, for example, charges 1,200 yuan ($180) to extract and transport up to 3 cubic meters of sewage to a facility about 20 kilometers from the lake.

'Critical' condition

The annual number of visitors to Dali increased from 15 million in 2011 to 39 million last year, according to the prefecture government. By contrast, the authorities say the volume of pollutants discharged every year into Erhai Lake has risen by more than 50 percent since 2004, although no specific figures are available.

"The situation in the lake has been critical since early this year," said Fu Zhongjian, deputy director of rural development for the Yunnan Housing and Rural-Urban Development Department, which is supervising the cleanup campaign. He compared the lake to a hospital patient in need of emergency treatment.

Erhai Lake has been hit by at least two major outbreaks of blue-green algae, a toxic type of bacteria that develops on the water's surface. Caixin magazine reported that 22,857 tons of overgrowth caused by pollution, including algae, was removed using two boats fitted with specialist equipment between November and March.

In addition, the authorities are attempting to tackle pollution at the source, with the Yunnan Development and Reform Commission having approved 4.5 billion yuan in funding for public-private partnership projects to improve water quality in the lake.

According to the Dali government, 3.49 billion yuan will be spent during the 13th Five-Year Plan period, from 2016 to 2020, with private companies brought in to help construct sewage treatment plants, pipelines and pumping stations.

Cost of progress

While residents and business owners around the lake were generally supportive of the cleanup efforts, some who talked to China Daily criticized the government for failing to plan for the area's tourism boom.

Zhai Qiang, 35, moved from his native Beijing to Caicun, a village on the lake's western shore, in 2014 to open a guesthouse with 19 rooms. He has spent 4 million yuan on the business, yet he said the sudden order to close his doors had put that investment in jeopardy.