SHENZHEN, July 18 (Xinhua) -- The water quality of the rivers in Shenzhen has been improving after more than 3 years of proper treatment.

More than 90 percent of the black and stinky water in the southern metropolis in Guangdong Province has been eliminated.

Shenzhen has 310 rivers flowing more than 1 square km in area each. The total combined length of the rivers stands at 999 km. During the city's development process, many of the rivers were tainted, giving out bad smells.

From 2016 to 2018, the city government spent more than 70 billion yuan (about 10 billion U.S. dollars) in funds to build pollution-treatment facilities, and transform residential districts.

In a national ranking of water improvement in May, Shenzhen took the top spot in Guangdong, indicating great progress in its water quality.