Shiyan City, Hubei Province is the core water source area of Danjiangkou Reservoir. It is the source of the middle route of the South-to-North Water Diversion Project.
Some enterprises illegally discharge domestic sewage and production wastewater into the Si River. The local environmental protection department has confirmed that the problem of sewage entering the river from the two factories involved is basically true. However, how this phenomenon occurred, and why it has not been effectively dealt with, needs to be seriously investigated.