This is People's Daily Tonight.

A woman's journey to protect the Nanming River in Guizhou

Eighty-one-year-old Lei Yueqin can often be seen walking along the Nanming River with a cane in one hand and a smile on her face as she reminds local fishermen to "pick up their trash" when they're done for the day. Lei's actions are often met with unpleasant stares. 

Lei Yueqin, 81, stands by the Nanming River in Guiyang, Southwest China's Guizhou Province. (Photos: Chinanews.com) 

Many people wonder why she likes to get into the business of others.

Lei says the Nanming River has been the water source for more than 600,000 Guiyang people, and most people understand her intentions.

She explained that when she sees people polluting the river or dam, she will walk right up and try to stop them. 

In the year 1984, 47-year-old Lei retired early from the recycling company where she worked.

She recalled the time when she was a little girl and almost died from dinking polluted water. From that moment on she dedicated her life to protecting Guiyang's natural water supply, a journey which has lasted 34 years.

In the 1970s, the Nanming River was a clean water source. With increasing economic development, the water quality worsened. Two decades later, nearly 100 factories were dumping waste into the stream.

The river that locals once drank from directly had become a "lifeless river."

To help local officials fight water pollution, Lei presented a color-coded, hand-drawn map detailing the river's pollution history over the course of 20 years.

A hand-drawn map by Lei Yueqin depicts pollution sources along the Nanming River. 

Red lines indicate heavily polluted streams and red dots represent pollution sources, typically factories and mines.

When comparing six of Lei's chronological maps, it is revealed that more water treatment plants have replaced factories.

Lei's equipment has also been upgraded from a notebook and a stick, to a smartphone device, which she uses to send pictures and documents to environment officials and friends.

Lei said her biggest wish is for younger people to realize the importance of protecting their environment.

And that's People's Daily Tonight. Thanks for joining us.

(Produced by Han Xiaomeng and Qiao Wai)