The researchers analyzed water quality in the Zhangweinan River basin using statistical methods. They found that the basin can be divided into two regions: one with good water quality and one with serious pollution. Over the years, water quality improved, but some areas still have poor water quality due to industrial and agricultural pollution. The main pollutants come from point sources like industrial wastewater and sewage, as well as non-point sources like agricultural runoff during heavy rain. These findings can help improve pollution control in the Zhangweinan River basin.