The researchers analyzed the water quality of Nansi Lake and its surrounding rivers by studying various parameters like chlorophyll a, total phosphorus, total nitrogen, transparency, and permanganate index. They found that the distribution of nitrogen and phosphorus in the lake is uneven, with some areas showing non-uniformity. Despite fluctuations in certain parameters, overall water quality has improved since 2004, with decreases in total phosphorus and chlorophyll a levels, and an increase in transparency. However, the water quality is still below the standard level, especially in Nanyang Lake, indicating severe eutrophication in some areas. This analysis can help in protecting resources, implementing the South-to-North Water Transfer Project, and promoting sustainable development in Nansi Lake.