The researchers analyzed how 15 rivers affect the water quality of Nansi Lake. They found that Nanyang and Dushan lakes were heavily polluted, while Zhaoyang and Weishan lakes had better water quality. Rivers flowing into the polluted lakes had high levels of organic pollutants, while those flowing into cleaner lakes had less pollution. The study showed that the quality of the rivers entering Nansi Lake is crucial for its water quality, suggesting that cleaning up these rivers should be a top priority.