According to the surveys from 1990 to 1991, the Wuli Lake entered a eutrophic period, which seriously affected drinking water supply and entertainment.The mean concentration of TN, TP, Chla, BOD and COD in the lake water were 2.25 mg/L, 111μg/L, 31.8 μg/L, 4.9 mg O₂/L and 17.5 mg O₂/L respectively.The water had a mean SD of only 0.51 m.The mud in the bottom contained 0.18% of nitrogen, 0.071% of phosphorous and 2.51% of organic matter.The phytoplankton dominated by diatom gave an annual productivity of 52 t/hm² (fresh algae), the main source of organic matter in the lake.To restore this lake,the pollutant input should be cut off by building sluice gates on its rivers and setting up waste water dispersing system around the lake.The mud should be removed from the lake bottom and water transport forbidden.Re-establishing aquatic vegetation in the Littoral zone would effectively promote the restoration of water quality and environment.It may be a good way to improve the drinking water quality in a short time by setting up a water source protective area in the eastern part of the lake and recovering aquatic vegetation in it.