Blue is the new green in southeast China's Xiamen, a port city in Fujian Province. Nearly 90 bird species live in the urban wetlands by Yundang Lake, now a thriving environment for diverse forms of life. These animals live in harmony with humans, in an area they both call home.

Yundang Lake has become a landmark green area in the city, and a prime example of harmonious coexistence between humans and nature. However, locals say the waters used to smell in the early 1980s, full of garbage, and poisoned by heavy pollution.

"It used to be unbearable to walk near the lake. The water was dark, and it stank. There weren't many birds either," a Xiamen resident told CGTN.

Change began in 1988, when Xiamen's then vice mayor, Xi Jinping – now the Chinese president – rolled out a plan to restore Yundang Lake. The city then introduced a raft of regulations, shutting down dozens of polluting enterprises.

Local residents also played a key role, taking charge of the management of the lake. 

Chen Yajin says he's found a sense of purpose in retirement – he's the chief overseeing the waters. "We inspect the lake and report issues to authorities. They attach great importance to our opinions and provide timely solutions to issues that we flag. I think the experience has provided a very good example for other districts in Xiamen," said the citizen lake chief.

A growing number of locals and tourists flock to the area to enjoy the beautiful scenery, as the waters improve year after year.

"My friend and I often hang out at the park, where we stroll, dance and sing. We send our thanks to the government for creating this beautiful environment," said a female resident.

"It's like our backyard," said another resident who lives near by the lake. She loves walking alongside the water with her grandson.

The restoration of Yundang Lake has set a clear example for other Chinese cities to follow. China's Ministry of Ecology and Environment says other parts of the world could also learn from the drastic changes that have taken shape there.

"The management of Yundang Lake is a signature of Xiamen's success. The landmark achievements have gained national influence, along with a global reputation," said Yu Hai, deputy director of the Research Center for Xi Jinping Thought on Ecological Civilization, adding, "It could provide Chinese wisdom and solutions to solve global issues that require ecological and environmental management in coastal cities."

Since 1984, the renovation of Yundang Lake has passed through five phases, with investment totaling some 2 billion yuan ($270 million). Xiamen's environmental campaign continues, and it's set to benefit more people for a greener future.