Abstract: This paper predicts the pollutant loads into the Three Gorges Reservoir after impoundment in 2010 and 2015 based on reference paper1. The authors employed envelopingline method to make three load levels: the low level, corresponding to the good condition, in which the pollution is controlled effectually; the high level, corresponding to the worst condition, in which the pollutant loads discharge get to worsen in a certain limit continuously; and the middle level, corresponding to the normal condition between the high and the low level. In the prediction, the background load from the Yangtze River, the Jialing River and the Wujiang River has been divided into two parts: the natural background load and the upstream contribution load. The natural background pollutant load kept constant and the upstream contribution load had high level, middle level and low level according to water pollution control planning of the upper reaches.The prediction results showed that the pollutant loads discharging to the reservoir directly occupy a low proportion of the total loads into the Three Gorges Reservoir. At middle load level, the pollutant loads from reservoir area occupy a proportion from 8.50% to 22.93% of the total loads. The main source comes from the background load, namely natural background load and upstream contribution load from the upper reaches of the Yangtze River, the Jialing River and the Wujiang River. At low, middle and high load levels, ignoring the natural background load, the reservoir area source BOD5 load occupies 28.8%, 32.5% and 35.04% of the total loads respectively in 2010. But the total phosphorus (TP) load shows some abnormality; the TP load at low load level is higher than that at middle load level, but lower than that at high load level.The main pollutant and distribution of the pollutant loads in 2010 and 2015 are similar to that in 1998. The main discharging district is the urban district of Chongqing City, the CODCr loads discharging at the high, middle and low levels are 39.6%, 36.2% and 21.6% respectively in 2010; and at low load level, the CODCr load decreases about 18% compared to that at high load level. The main pollution source of the reservoir area is the agricultural nonpoint sources, the CODCr load of the agricultural nonpoint source from reservoir area occupies 38.9%,47.5% and 70.4% of total loads at high, middle and low load level respectively in 2010. The prediction results also showed that pollutant loads exhibit increasing trend with the social and economical development of the reservoir area, and the pollutant loads and the three load levels in 2015 will be larger than that in both 2010 and 1998.

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