The Dong River is the eastern tributary

Tributary

A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...

 of the Pearl River

Pearl River (China)

The Pearl River or less commonly, the "Guangdong River" or "Canton River" etc., , is an extensive river system in southern China. The name Pearl River is usually used as a catchment term to refer to the watersheds of the Xi Jiang , the Bei Jiang , and the Dong Jiang...

 in Guangdong

Guangdong

Guangdong is a province on the South China Sea coast of the People's Republic of China. The province was previously often written with the alternative English name Kwangtung Province...

 province, southern China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

. The other two main tributaries of Pearl River are Xijiang River

Xijiang River

The Xi River is the western tributary of the Pearl River in China. It is formed by the confluence of the Gui and Xun Rivers in Wuzhou, Guangxi. It then flows east through Guangdong, and enters the Pearl River Delta just east of the Lingyang Gorge in Zhaoqing. The main branch of the Xi flows...

 and Beijiang River

Beijiang River

Bei River is the northern tributary of the Pearl River in southern China. The other two main tributaries of the Pearl River are the Xijiang River and the Dongjiang River....

.

The Dong River is a major source of water for Hong Kong

Hong Kong

Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...

. The Hong Kong Government has purchased Dong River water

Water supply in Hong Kong

Providing an adequate water supply for Hong Kong has always been difficult because there are few natural lakes, rivers or substantial groundwater sources and of its high population density. About 70% of water demand thus is met by importing water from the Dongjiang River in neighboring Guangdong...

 from Guangdong

Guangdong

Guangdong is a province on the South China Sea coast of the People's Republic of China. The province was previously often written with the alternative English name Kwangtung Province...

 since 1965. Over 70% of domestic water in Hong Kong is imported from the Dong River. Its discharge is about 807.5 m3/s.

Places along the river include

• Ganzhou
  Ganzhou
  Ganzhou is a prefecture-level city in southern Jiangxi province, People's Republic of China. Its administrative seat is at Zhanggong .-History:...
  
  (赣州)
• Xunwu(寻乌县)
• Heyuan
  Heyuan
  -Language:In the great majority of Heyuan areas, Hakka Chinese is in general use.In the greater part of areas in the city, Dongyuan County, Lianping County, Heping County, Longchuan County etc., it belongs to the Yuezhong dialect group, while in Zijin County and part of Longchuan County, it belongs...
  
  (河源)
• Longchuan(龙川县)
• Dongyuan(东源县)
• Yuancheng District
  Yuancheng District
  Yuancheng District is a district of Guangdong Province, China. It is under the administration of Heyuan city....
  
  (源城区)
• Huizhou
  Huizhou
  Huizhou , historically known as Waichow, is a city located in central Guangdong province of the People's Republic of China. Part of the Pearl River Delta, Huizhou borders the provincial capital of Guangzhou to the west, Shaoguan to the north, Heyuan to the northeast, Shanwei to the east, Shenzhen...
  
  (惠州)
• Boluo
  Boluo County
  Boluo County is a county of Guangdong Province, China. It is under the administration of Huizhou city.-Economy:Boluo County is said to be the home to the country's largest farm for raising the rare "Golden coin turtle" Cuora trifasciata.-Notes:...
  
  (博罗县)
• Huicheng District
  Huicheng District
  Huicheng District is a district of Guangdong Province, China. It is under the administration of Huizhou city. Location:...
  
  (惠城区)
• Dongguan
  Dongguan
  Dongguan is a prefecture-level city in central Guangdong province, People's Republic of China.An important industrial city located in the Pearl River Delta, Dongguan borders the provincial capital of Guangzhou to the north, Huizhou to the northeast, Shenzhen to the south, and the Pearl River to...
  
  (东莞)