He Licheng, owner of a licensed inn in the village of Gusheng, processes wastewater through a septic tank and sewage treatment unit and then transfers it to a village sewage treatment plant. All of the village's wastewater has to be processed before it is returned to Erhai Lake.

Gusheng, west of the lake, is in the Dali Bai autonomous prefecture of Yunnan province.

The strict treatment measures have been instituted since President Xi Jinping visited on Jan 20, 2015. During that trip he spoke highly of the natural environment and traditional Bai houses. He asked people to protect the lake after taking a photo with local officials there.

"I'll keep this photo as evidence. When I come back in a few years, I hope to see the water even clearer," Xi said.

In the village, which dates back over 2,000 years, people used to make a living directly from the lake. Inn owner He, 50, previously had a powerboat and fishpond businesses he started in the 1980s.

But the lake was contaminated by blooms of blue-green algae in 1996 and 2003 as human activity increased.

This year, the lake's water has been graded Class II through May, whereas it attained that level for only the first four months last year, before falling to Class III, according to the environmental protection agency of the prefecture.

"Generally speaking, Class II water means you can drink it directly, and Class III means you need to process it before drinking it," said Cao Te, an associate researcher at the Institute of Hydrobiology, Chinese Academy of Sciences.

Cao has been studying the lake's ecosystem since 2006.

"May is when rains that pick up pollutants first arrive at Erhai and the aquatic plants start to grow because of rising temperatures," Cao said. "This May, the water has been so much better."

Cao is helping restore the ecosystem of the lake. He has planted different types of vegetation to help keep the water clean.

The whole village realized the importance of protecting the lake after Xi's visit.

He Qiaokun, head of the village, said: "Aside from the improvement of the garbage collection and sewage treatment systems in our village, environmental awareness has increased. Villagers used to throw garbage directly into the lake, but now nobody does that, and they don't need any supervision."

Some measures have led to a temporary drop in villagers' income.

"They know it is all for the good in the long run," He Qiaokun said. "The next step is to develop rural tourism. After the shift they will have better incomes than farming."

In 2015, Xi asked the people of Gusheng to preserve the natural beauty of the village and to protect the lake.

After He Licheng's powerboat and fishing boat businesses were closed by the government, he had to move to the lake's western shore to make a living, away from his family. But he missed his wife and children and returned to the village in 2016 to take over management of an inn from his son.

The inn is close to the lake and next to Li Dechang's house, which Xi visited in 2015. Xi talked with He Licheng during his visit, asking about his family.

He Licheng's inn, opened in 2012, made a profit only around 50,000 yuan ($7,520) a year at first. After Xi's visit, more tourists visited Gusheng, bringing him 150,000 yuan in annual profit in 2015 and 250,000 yuan in 2016.

But in March, the prefecture announced that the core areas of the Erhai Lake ecological protection zone would need work to improve the environment, and asked all inns and restaurants within such areas to stop doing business for a few months.

He Licheng's inn and more than 1,000 other commercial establishments around the lake are in the zone. Some that closed on April 8 reopened in late September with proper licenses.

"We live near the lake, so we want it to be clean so that our children can enjoy it, too," He Licheng said. "If the lake gets clearer, it will attract more tourists and our lives will get better.

"Everything we do now is according to President Xi's suggestions."