Abstract: This paper summarized the real pollutant loads into the Three Gorges Reservoir before impoundment, in which the pollutant loads from Reservoir Area consist of those caused by the household sewage, industrial sewage, agriculture pollution and shipflowing pollution. The background pollutant loads by the upstream Yangtze River, two major tributaries Jialing River and Wujiang River were analyzed and divided into two parts of the upstream natural background pollutant load (UNBPL) and the contribution pollutant load (CPL) of upstream manmade pollution. All above provided the basis for the water pollution control of the Three Gorges Reservoir. The results had shown that: (1) the total load of pollutants (including CODCr, BOD5, NH3N and TP) into the Three Gorges Reservoir in 1998 were respectively annually 4.489 9×106,9.795×105,1.005×105 and 8.27×104 tons, in which those from the Three Gorges Reservoir Area were respectively 3.941×105,1.887×105,1.3×104,and 1.56×104 tons;(2) the main contribution pollutant loads were the upstream background load from the upstream Yangtze River, two major tributaries Jialing River and Wujiang River, containing UNBPL and CPL. The CODCr load of UNBPL was slightly smaller than that of CPL.The BOD5 and NH3N loads of CPL were slightly larger than those of UNBPL. And the TP load of CPL was grealtly larger than that of UNBPL. So the pollution control of the upstream Yangtze River, two major tributaries Jialing River and Wujiang River should be the major issue for the Three Gorges Reservoir;(3) The major pollutants in the Reservoir Area were organic substances (pollutants) such as TP, BOD5,TN and CODCr.whose ratio of accumulative pollution load over 98%. The major pollution source was runoff formed by the agriculture, whose ratio of accumulative pollution load 77.85%.Next was household sewage, whose ratio of accumulative pollution load 19.45%. And the ratio of accumulative pollution load for the industrial sewage occupied 1.62%. Hence, the agriculture source will become the key issue for the Reservoir Area; (4) regarding the spacial distribution of pollution sources in the Reservoir Area, the upstream downtowns of Chongqing Municipality City was the major region discharging pollutants into the Three Gorges Reservoir. The discharge loads of CODCr and BOD5 were respectively annually 1.31×105, 5.6×104 tons, corresponding to 33.2% and 29.6% of total pollutant load in the Reservoir Area. Hence, the upstream downtowns of Chongqing Municipality City will be the major pollution control region.

Key words: Three Gorges Reservoir, pollution source, pollutant loads