Case Study 2.8: China`s Three Gorges Dam (TGD): Costs vs. Benefits

Human activities often affect water resources, with impacts sometimes local and limited and other times, widespread and substantial. Some actions can even permanently alter the structure and function of major aquatic ecosystems. There may be no better example of this later case than the construction and operation of large dams on major rivers, with both short- and long-term consequences possible above and below the dam.

In this case study, we’ll look at how the TGD has altered environmental conditions in the Yangtze River. We’ll focus on two important aspects: (1) how the TGD has affected fish populations in the river and (2) how TGD operation has altered pollutant behavior in the ecosystem. We’ll consider impacts both above and below the TGD.

Before you start, review some of the Background Materials on the large dams, the Yangtze ecosystem and the Three Gorges Dam presented here.


Background Materials:

General information on the types of large dams:

For information about how dams generate electricity, go to

For background on the Yangtze River, its watershed and its issues, visit the Great Rivers Partnership’s website:

For more information on the Yangtze River dolphin, visit

Textbook References and Links:

Exercise 2 and 3:  Gao et al. 2010 article on Yangtze River fish communities:

Exercise 4:  Lian et al. Xiangxi chlorophyll concentrations paper:

Exercise 5:  Wang and Zhang article on mercury contamination implications for the Three Gorges Reservoir:

Exercise 7 and 8 helpful materials:
Cost-benefit analysis of large-scale dams: as you prepare your positions on the pros and cons of
large-scale dams, you might find these websites helpful:

Exercise 9 helpful materials:
Micro dams:  a concise look at the pros and cons of micro dams for generating electricity is presented on this website:


Downloadable data and files:

Exercise 1:  TGD.kmz

Exercise 2 and 3:  Gao 2010.pdf 

Exercise 4: Lian 2014.pdf

Exercise 5: Wang 2012.pdf

Exercise 7 and 8: To dam or not to dam.pdf