The researchers studied water quality in two farming areas in China to see how rivers affect lake water. They found that when the rivers had high levels of certain pollutants, the lake water also had high amounts of those pollutants. Monitoring showed the lake had the most pollutants in late 2004. The study used a method called grey relationship analysis to show a strong link between river and lake water quality. The researchers discovered that pollution from the farm fields quickly affected the lake's water quality. This suggests that pollution from farming areas plays a big role in the pollution of lakes.