River damming can damage downstream environments by retaining sediments. Sediment problems are always heavily emphasized in discussions of the Three Gorges Project. When the TGD started operating in 2003, the Yangtze downstream entered a stage of sediment reduction. During the first 2 years of impoundment (2003–2004), sediment discharge at Yichang (first station downstream the dam) decreased by 164 million tons (Xu et al. 2006).