Water quality in the Qinhuai River Basin, East China was studied using statistical techniques and a water quality index. The researchers found that pollution sources varied by season, with urbanization and wastewater being major contributors to organic pollution, while agriculture and industry were main sources of nutrients. Water quality was mostly slightly to moderately polluted, with a trend of deterioration from 1990 to 2005, improvement from 2006 to 2010, and then deterioration again. Areas with more urban development showed higher pollution levels. The study shows that these methods can help assess water quality for decision-making.