The study analyzed nitrogen levels in twenty rivers around Taihu Lake to understand pollution sources. Results showed that most rivers were polluted, with inorganic nitrogen being the main type. Heavy and medium polluted rivers had higher nitrogen levels in dry seasons due to lower removal efficiency. Point source pollution was the main source in these rivers. Light polluted rivers had similar nitrogen levels in both seasons, indicating equal point and non-point source pollution. To improve water quality, controlling point source pollution in heavily polluted rivers is crucial, while both sources should be managed in lightly polluted rivers.