Unfortunately, the world's largest dam comes at great expense, not only financial, but environmental, cultural, and human.
The dam will threaten the river's wildlife, especially the fish population by limiting access to spawn sites and potentially increasing pollution. It will affect the habitat of a number of species, including the Yangtze dolphin, the Chinese Sturgeon, the Chinese Tiger, the Chinese Alligator, the Siberian Crane, and the Giant Panda. Already the numbers of Yangtze dolphin have dropped dramatically from 400 in the early 80s to six in 1999. In 2000, 70 researchers looked for two months and found none. Yangtze dolphin only live in the Yangtze. Construction of the dam will require extensive logging to clear areas to be submerged. Without the silt that will be caught behind the dam, the water flowing to the sea will erode the mudflats on the coastline which protect it from storms and rising tides.
The environmental effects of the dam are not entirely unknown, even in Communist China. In 1989, one Chinese environmentalist, Dao Qing published a book of essays from prominent scientists and ecologists criticizing the Three Gorges Dam Project. In the midst of heavy pressure from the Communist government to conform to its ideology, the publication of "Yangtze! Yangtze!" marked what Far Eastern Economic Review would call "a watershed event in post-1949 Chinese politics." For the first time since the cultural revolution, the country's intelligentsia dared attempt to influence the political process. The book was produced in under four months in order to reach delegates attending the Chinese People's Political Consultative Conference meetings in March and the National People's Congress (NPC), where they were expected to make a final decision concerning the dam project. Dao Qing was subsequently imprisoned for 10 months, and many believe that the protest contributed to the government's (read Li Peng's) response to the student protests in Tienanmen square.
Unfortunately the evironmental damage does not stop with endangered species, it may also poison those who depend on it. In 2001, 23.4 billion tons of raw sewage and industrial waste were dumped into the Yangtze and subsequently flushed to the sea. The dam would keep back the waste along with the water. Even after putting new environmental protection laws in place, the government still expects that one billion tons of waste will be dumped into the Yangtze annually. Parts of the riverbank are already too polluted for human use. Moreover, the river now submerges more than 1,600 factories and abandoned mines that may create a hazard for the people and animals who live on the river. As if that weren't enough, before the river was dammed, the operation to remove toxic waste from the reservoir fell behind schedule.