Erhai Lake offers stunning scenery. CHEN RUOQUE/ZHANG SHULU/FOR CHINA DAILY

As the sunset glow reflected on rippling Erhai Lake, visitors and shutterbugs followed paths along the lakeside accompanied by the chattering of black-headed gulls, looking for the best spot to capture the spectacular view.

The picture-perfect scenery has become an increasingly common sight at Erhai thanks to its improved environment over the past few years.

The lake in the city of Dali, Yunnan province, sits about 2,000 meters above sea level and covers more than 250 square kilometers. Dubbed the "mother lake" by local residents, the ear-shaped freshwater lake attracts tens of millions of tourists every year.

For He Licheng, a 51-year-old farmer from Gusheng village on Erhai western shore, a clean Erhai is among his most cherished memories.

"When I was a child, the villagers used to fish and swim in Erhai. We even drank directly from it," He recalled.

However, the lake became polluted with the start of urbanization in the 1980s and the rise of tourism in the 1990s. As a growing number of tourists flocked to Dali, hotels, guesthouses and restaurants mushroomed on the lake shores, intensifying the pollution.

With untreated sewage, garbage and animal waste discharged into the water, Erhai saw major outbreaks of toxic blue-green algae in 1996, 2003 and 2013.

"At that time, the lake was dark, and we could smell the stink. It was a big turnoff for tourists," said He, who opened a guesthouse in his village in 2012. "We worried that tourists might no longer come to visit."

Alarmed by the worsening water quality, the local government launched a campaign in 2016 to control and prevent pollution and restore the lake's environment.

More than 2,400 guesthouses and restaurants by the lakeside were asked to suspend business to upgrade sewage treatment facilities. Blue and green algae treatment facilities were put in place around the lake, and a waste disposal factory was built to turn animal waste into organic fertilizer.

Like many of Dali's guesthouse owners, He suspended his business for almost a year and dismantled two rooms at his guesthouse after receiving government compensation because they were located too close to the lake.

"We owe our business success to Erhai, and it's time for us to contribute to its protection," He said.

According to official data, more than 20 billion yuan ($2.8 billion) has been invested to improve the lake's environment over the past five years.

The arduous efforts have paid off. In the first eight months of this year, the surface water quality of Erhai Lake was graded Class II, which indicates good water quality, according to the Yunnan provincial department of ecology and environment.

"A better environment will bring more tourists. Though I have fewer rooms in my guesthouse, I'm very confident about my homestay business," He said.

China will advance green development and promote harmony between people and nature, according to a communique released after the Fifth Plenary Session of the 19th Central Committee of the Communist Party of China in late October.

The country will promote all-around green transformation in economic and social development and continuously improve the environment, the communique said.