This photo taken on February 21, 2017 shows fishermen in Tongguan, Shaanxi Province have returned to catch fish in the Weihe River.
Water quality is returning to normal in the Weihe River in China's central-west Shaanxi Province, after strenuous efforts by the government and local people over the past decade.
The 818-kilometer Weihe River, the Yellow River's largest tributary, turned from a natural yellow to a dark color when the country's economy took off in the early 1980s.
Numerous pollutants were released from factories along the river at that time without sufficient water treatment, especially from paper-making and fertilizer plants.
In 2004, Shaanxi local authorities said the river had lost all of its natural functions. Monitoring data showed that the river contributed to around 18 percent of the sewage in the Yellow River Valley at that time.
To tackle that, drastic measures were adopted over the next decade, and became stricter in recent years. In 2011 alone, three major cities along the river, including Baoji, Xianyang, and Xi'an, were fined a total of 89 million yuan (13 million US dollars) for excessive pollution. And more than one hundred polluting factories along the river were also shut down in the past decade.
Now the water seems to have returned to its natural yellow color. In Tongguan, Shaanxi Province, where the river flows into the Yellow River, monitoring data show key water pollution indicators, like ammonia nitrogen density, are much lower. Fishermen have even returned to the river to catch fish in recent years, and have reported reeling in fish weighing more than 20 kilograms.
Local residents living along the river are happy to see the changes, but they also hope to find a way to balance economic development and still live in a good, clean environment.