The Liangtan River in the Three Gorges Reservoir region is heavily polluted, affecting water quality. A study analyzed pollution sources like agriculture, sewage, and industry, finding that most sections of the river exceed national water quality standards. During rain, urban non-point sources and natural factors contribute more to pollution, while in dry periods, agriculture and industry play a bigger role. Upstream pollution is mainly from sewage and industry, while downstream pollution comes from urban sources and natural factors. Agricultural sources are a major contributor to nitrogen pollution in both branches of the river.