While point source pollution gets controlled, nonpoint source pollution has increasingly endangered urban waters around the world. In this paper, taking East Lake in Wuhan as the case study, this study defined the researched water basin and land use types and made a quantitative analysis on water quality statistics. Based on this, this study modeled and analyzed the correlation between land use type and lake water quality, and made a tentative exploration about seasonal effect on water quality of the East Lake and other influencing factors. The results showed that, land use type and climatic change exert a significant impact on water quality of the East Lake. Among others, farmlands and construction lands are the main source of nonpoint source pollution to the lake; green spaces and pond could effectively retain or absorb pollutants, and thus maintain lake water quality; additionally, affected by such climatic factors as precipitation and temperature, water quality changes with seasons.