Water Quality Evaluation for the Main Inflow Rivers of Nansihu Lake

Based on water quality monitoring data of four inflow rivers of Nansihu Lake in 2006, 2007 and 2008, the water qualities were evaluated according to the method of comprehensive water quality identification index, with the indicators of dissolved oxygen, CODMn, biochemical oxygen demand and ammonia nitrogen. The results show that the rivers has been in the state of serious pollution, in which the monitoring section of Si River was in Grade III of water quality standard, and others were in Grade IV and V. The evaluation results have offered interesting scientific basis for environmental controlling to the inflow rivers of the Nansihu Lake.