As 59-year-old Li Yunli remembers it, the water in Dianchi Lake in Kunming, Yunnan's provincial capital, was so clean that residents could drink from it directly when she was a child.

But the raw sewage generated during the city's rapid urbanization and industrialization in the 1980s left the lake with a permanent stench. Local residents avoided it, even though they had once depended on its fish for their livelihoods.

Many chose to change jobs and go elsewhere to earn a living, but not Li.

Instead, she devoted herself to cleaning the lake, which was once dubbed a "pearl" of the Yunnan-Guizhou Plateau.

She has been cleaning the lake for 35 years now, and her perseverance has earned her the honor of being selected as one of China's 100 model environmental protection volunteers this year.

Li's home village of Xinhua is located near Caohai, which sits on the northern shore of Dianchi. For many years before the turn of the millennium, eutrophication resulting from heavy pollution caused the channel connecting Caohai with other parts of Dianchi to become blanketed in a thick layer of blue-green algae.

In 1987, when local authorities launched a volunteer program to deal with the proliferation of water hyacinths, Li didn't hesitate. The following year, the local women's federation created an all-female salvage team to conduct regular cleaning work in the lake. Li was chosen as leader of the 40-strong team.

Since then, she and her team can often be seen starting work at 7 am. Braving sunshine and rain, they fill their boats with water plants and trash, rather than the bounties that previously brought them all wealth.

The most challenging period runs from June to August, when the blue-green algae grows fastest. Erratic winds during this period mean that plants and trash are blown in many different directions, and occasional rainfall makes the work harder, as does the stronger stench emanating from the lake.

They work day after day, stopping only in the event of a downpour.

"I grew up near Dianchi. I'm cleaning it not only for the lake's sake, but also for myself and for future generations," she said.

To save time and energy, they bring food with them so that they don't have to row home for lunch. Li's efforts have tanned her skin and left her hands with thick calluses.

There have been positive changes to the lake thanks to the team's perseverance and also to the increasing importance local authorities now attach to the treatment of its waters.

In 1991, the Kunming government built the city's first sewage treatment plant. Now, there are 28 of them in the city. Thousands of kilometers of sewage pipes have been laid downtown and around Dianchi to prevent waste water from entering the lake.

In 2016, Dianchi bade farewell to water below Grade V quality, the lowest level in the national five-tier grading system for surface water. Since then, water quality has stabilized at Grade IV.

Women have joined and left the team over the past three decades, but Li believes it is much stronger now compared to the start. At its peak, the team had around 100 members.

"As long as I am sincere in taking the lead in the cleanup, more people will join us to protect Dianchi, and the lake will return to its previous state with water that can be drunk directly," she said.