Abstract: Status quo was investigated and evolution trend analyzed of eutrophication in 25 lakes in the typical lake regions of China, and causes of the eutrophication in these lakes explored. Results show that about 52% of the investigated lakes were at eutrophication level status during the period from 2009 to 2010. Lake Hunlun in Inner Mongolia, as well as the lakes in Jiangsu were severely eutrophicated and the lakes in Northeast China were at moderate eutrophication level, while those in Xinjiang at low eutrophication level. However, the lakes in Yunnan have evoluted into two extremes in eutrophication. In the past 30 years. 16 (80%)of the total 25 lakes investigated demonstrated a significant rising trend in eutrophication, indicating that this period is one of rapid development of lake eutrophication in China. Alpine lakes in Yunnan, in particular, are the most significant in eutrophication, while the lakes in Jiangsu show a eutrophicating trend that is not optimistic, either. The investigation suggestes that human activities are the major cause of the eutrophication. As the point source pollution has been gradually put under control, agricultural non-point source pollution has emerged as the primary source supplying nutrients to lakes in Jiangsu, Yunnan and Northeast China, causing eutrophication, which deserves attention from all the aspects concerned.

Key words: lake eutrophication, comprehensive nutrition state index, agricultural non-point source pollution, lake water quantity