Application of Total Maximum Daily Load( TMDL )Program to Total Amount Control of Water Pollutants in Changhu Lake

In recent years,water quality in Changhu Lake has been deteriorating rapidly. The non-point source pollution caused mainly by agriculture and aquaculture in particular,accelerated the eutrophication process. To improve the water quality,a water environmental management mode based on total maximum daily load(TMDL)program is developed. Water environmental capacities of COD,TP,TN and the present point source and non-point source pollution load are estimated.Then,pollutants reduction rate are clearly determined and pollution control measures eventually put forward. The results show that the water environmental capacities of COD,TP,TN are 26 438.43,90.78,1 815.56 t/a respectively and the pollution load of COD,TP,TN into the Lake is 14 137.74,271.23,24 85.24 t/a respectively. COD need not be reduced,however,eutrophication factor TP,TN greatly exceed its standard and pollutants reduction rate for TP and TN reach up to 68.20 % and30.60% respectively. Particularly,non-point source pollution caused mainly by agriculture and aquaculture has such a great impact on TP and TN that targeted measures are urgently needed.