Turning the tide on Fujian's stinky Yundang Lake

XIAMEN, Aug. 22 (Xinhua) -- As Chen Yajin patrols the Yundang Lake in Xiamen, east China's Fujian Province, he stops to watch the egrets flying among the lush mangrove forests, and reflects on the transformation that has taken place in the coastal city he calls home.

Chen, 64, works as a "citizen lake chief," leading teams of volunteers in keeping the lake clean, protecting the mangroves and preventing illegal fishing. The area is well known these days for its clean water, mangroves, egrets and other wildlife.

However, Chen recalls another time, just a few decades ago, when the lake was in a terrible state, filled with pollution and a place to be avoided by animals and humans alike.

"The birds in Yundang Lake had gone, the ecology had been destroyed, and its stench could be smelled from a long distance," said Chen. "I would always cover my nose and mouth and pass by quickly."

The Yundang Lake basin covers an area of 37 square km. Once a harbor connected to the sea, it was well known for its fishing culture. The nighttime view of lights on fishing boats was one of the eight magnificent scenes for which Xiamen was famous.

In the 1970s, people reclaimed land from the sea in order to increase grain production, and Yundang became an inner lake. As the population and factories increased, water pollution grew steadily. Industrial wastewater from over 100 factories was discharged directly into the lake, together with untreated sewage from hundreds of thousands of local residents.

By the early 1980s, the water quality had hit an all-time low, while piles of litter and overgrown weeds had invaded the lake, as did mosquitoes and flies.

Like many other residents, Chen began to wish he could avoid the lake, which had become a poisonous, stinking swamp.

Then, in the mid-to-late 1980s, efforts were made to turn the tide and restore the lake to its former state of health. The local authorities took proactive measures to address environmental damage and foster sustainable approaches to development.

The measures included halting the discharge of untreated sewage, creating drainage ditches and building banks. The dredged mud was used to build up the tidal flats around the island where the egrets lived, boosting the mangrove forest that was their natural habitat.

One of the most successful measures has been the use of natural tides to draw sea water into the lake. A 6.5-km pipeline had been installed to transport sea water to upstream lakes, which in turn reinvigorates the waters in Yundang Lake.

Wei Daojun, director of the Xiamen Yundang Lake Conservation Center, said that natural restoration is the main means of protecting the lake's environment, and the center will continue to enrich the population of various species by enhancing the resilience of the ecosystem.

Moreover, the center has explored new methods of protection, such as recruiting citizens with professional knowledge to participate in the lake's management.

Among the key measures is the recruitment of three "citizen lake chiefs" to lead volunteers in various ecological protection duties. Chen is one of the three leaders drawn from the local community.

So far, four phases of ecological restoration work have been carried out, including the dredging work, with a total investment of 1.13 billion yuan (about 156.96 million U.S. dollars). The fifth phase is currently underway.

The efforts have paid off. Chen said the lake's ecology has improved enormously in the past two decades, proof that the government's investment has been effective.

"There are up to a thousand egrets living here," said Wei, pointing at the mangrove-dotted island in the middle of the lake. To protect the birds, tourists are banned from visiting the island.

Compared with other ecosystems, the mangrove forests on Yundang Lake possess unique advantages as a habitat for egrets, said Wei, offering the birds an ideal place to forage.

The lake shore, meanwhile, provides a suitable place for tourists and local residents to relax, enjoying the shade of the densely packed trees there, including banyans, king coconuts and flame trees.

According to the 2022 Xiamen Ecological Environmental Quality Bulletin, last year, the main pollutants in Yundang Lake were inorganic nitrogen and active phosphate, and their concentrations decreased by 12.2 percent and 13.9 percent, respectively, compared with 2020.

Xiamen is planning to build a smart management platform for municipal gardens and parks to further improve the efficiency of management, said Wei.