It's five years since the completion of the South-to-North Water Transfer Project. The once-controversial scheme now plays a vital part in ecological restoration in northern China.  

A man-made green belt that transfers billions of tons of water from southern China to the north. Cities along this thousand-kilometer journey are feeling the benefits.

"Since the ecological water compensation began in 2018, the groundwater level has been raised about one meter," said Li Kelun, Deputy Director of Hutuo River Construction & Management Department of Shijiazhuang City, Hebei Province.

Lack of water has been a major restraint on the development of northern Chinese cities. The Hutuo River dried up because of the lowering water level. The water from the south has saved the river in Shijiazhuang, and helped other cities improve the quality of their drinking water.

The project has the most protected water in China.

Today, they are testing a new floating platform that will deal with pollution emergencies.

"We develop this platform to handle emergencies such as dangerous and chemical products being poured into the canal by accident. It integrates a lot of equipment with improved efficiency," said Zhang Zhiyong, deputy manager of Huanghe Machinery Plant. 

Platforms like this are being allocated along the canal. With fences and cameras also being installed, the water surface is closely monitored. 

"In our section, we have two water quality monitoring stations that automatically test the quality eight times a day," said Cao Mingze, deputy dnrector of Shijiazhuang Management Department, South-to-North Water Transfer Project.

The canal is now an important source of drinking water for cities including Beijing and Tianjin. It is also a important supplement to the water resources in northern China, helping to protect the environment there. 

The grand water diversion project consists of three routes, among which the first phase projects of the eastern and middle routes went into operation in 2013 and 2014, respectively. The western route is still in pre-construction stage.

For the eastern route, water is pumped from the Yangzhou section of the Yangtze River in east China's Jiangsu Province and transported northward to Shandong Province. 

The middle route carries water from the Danjiangkou Reservoir at the border of Hubei and Henan provinces in central China all the way northward to Beijing and Tianjin. Residents in Henan and Hebei provinces along the route also benefit from the water. 

According to the Ministry of Water Resources, the south-to-north water diversion project has transported over 30 billion cubic meters of water from the Yangtze River to the northern part of the country over the past five years, benefiting more than 120 million people.