The Guangdong government will continue to secure the water supply for Hong Kong, making the Pearl River Delta project a top priority, according to the head of the provincial department of water resources.

The Pearl River Delta Water Resources Allocation Project, which is designed to pump water from the Xijiang River valley to the Dongjiang River valley, will guarantee the water supply for Hong Kong in emergencies such as severe droughts.

The construction of the 34.8 billion yuan ($5.13 billion) project will start this year, with half of the work to be done by 2020.

"The Guangdong government and all the subordinate city governments place great importance on the task of securing the water supply for Hong Kong. People living in the Dongjiang River basin also pay a lot of attention to water quality," said Xu Yongke, head of the water resources department of Guangdong.

"We will keep on strengthening water protection and push forward the construction of water allocation projects."

To ensure water quality, the governments of six cities in the Dongjiang River basin - Guangzhou, Shenzhen, Shaoguan, Heyuan, Huizhou and Dongguan - have refused about 7,000 projects since 2011 that might influence the river's water quality.

These six cities have spent about 42.1 billion yuan since 2011 on constructing sewage treatment and garbage disposal facilities to protect the water environment. There are altogether 142 sewage treatment facilities in the Dongjiang River basin, handling 9.25 million tons of sewage every day.

Hong Kong, a seaport with few natural lakes or rivers, has relied on mountain streams and rain as its main sources of fresh water. It suffered a long drought from May 1963 to June 1964, when residents were supplied with fresh water only once every four days.

Concerned about Hong Kong's difficulty in acquiring fresh water, the central government undertook the Dongjiang-Shenzhen Water Supply Project in February 1964. More than 10,000 construction workers spent 11 months on the project, which began operations on March 1, 1965.

Water from the project has been hailed as the lifeblood of Hong Kong ever since, accounting for 70 to 80 percent of the special administrative region's annual fresh water consumption.

By the end of 2016, the Dongjiang-Shenzhen Water Supply Project had supplied Hong Kong with 23.7 billion cubic meters of water. The project's annual water supply for Hong Kong is currently between 700 million and 800 million cu m.

Ma Siu-cheung, secretary for development of Hong Kong, extended thanks to Guangdong for its efforts to secure Hong Kong's water supply during his visit to the provincial department of water resources in March.

"Although some people in Hong Kong keep questioning the water quality of Dongjiang River, it is in complete conformity with set standards," Ma said.

"The water supply arrangement is reasonable and effective, and I believe that Guangdong and Hong Kong will continue good cooperation in the future."