Water pollution in Taihu Lake region is mainly caused by non-point sources, leading to serious eutrophication. A study compared pollution levels in the rainy and dry seasons, finding high concentrations of total phosphorus, total nitrogen, and ammonium. Total nitrogen was higher in the rainy season, and total phosphorus was significantly higher in Xinzhuang compared to Wangzhuang and Yixing. Phosphorus pollution in Taihu Lake was worse than in irrigation and urban water sources. The main factors affecting surface water were nitrogen, phosphorus, and CODMn, while ammonium nitrogen was the key factor in groundwater pollution.