Enclosed Water Bodies

In 2003, 28 major lakes and reservoirs were monitored. Among them, one was Grade II, accounting for 3.6%; six were Grade III, accounting for 21.4%; seven were Grade IV, accounting for 25%; four were Grade V, accounting for 14.3%; and ten were worse than Grade V, accounting for 35.7%.

Taihu Lake:
The water body was seriously polluted. Among the 21 sections monitored, none was within Grade I-III. Grade IV, V and/or worse accounted for 14.3%, 14.3%, and 71.4% of all sections monitored respectively. However, significant improvement was observed as compared with the water quality of the previous year. The main pollution indicators were total phosphorus and total nitrogen. The nutrient index was 57.8, which was light eutrophication.

Quality Grades in main body of Taihu Lake

Dianchi Lake:
Dianchi Lake was seriously polluted. Compared with the previous year, the water quality had declined slightly. The water quality of both Caohai and Waihai was worse than Grade V. Caohai was more polluted than Waihai. The permanganate index of Waihai met Grade III standards. Total phosphorus was Grade V. The main pollution indicators were total nitrogen and total phosphorus. The nutrient indexes were 76.4 and 62.7 respectively for Caohai and Waihai, and was 72.0 for the entire lake on average. This indicated that the lake had serious eutrophication problems.

Chaohu Lake:
The western part of the lake was worse than Grade V. The eastern part of the lake was Grade V. On the average, the lake was worse than Grade V. Compared with the previous year, the water quality was about the same. Permanganate index reached Grade III water quality standards. The main pollution indicators were total nitrogen and total phosphorus.

Other Large Lakes:
Among the 10 other large fresh water lakes, Xingkai Lake was Grade II, Erhai and Bositeng were Grade III, Hongze and Boyang were Grade IV, Dongting was Grade V, Nansi, Baiyangdian, Dalai, and Jingpo were worse than Grade V. The main pollution indicators were total nitrogen, total phosphorus, and BOD. Erhai, Dongting and Boyang had medium eutrophiciation. Hongze, Dalai, and Nansi had light eutrophication.

Lakes in Cities:
Lakes in cities had poor water quality. Kunming Lake of Beijing and the Xihu Lake of Hangzhou were Grade IV. Xuanwu Lake of Nianjing, Donghu Lake of Wuhan, and Daming Lake of Jinan were worse than Grade V. The main pollution indicators were total nitrogen and total phosphorus.

Large Reservoirs:
Among the 10 large reservoirs monitored, Miyun Reservoir, Qiandao Reservoir, Shimen Reservoir, and Dongpu Reservoir were Grade III, Yuqian Reservoir and Danjiangkou Reservoir were Grade IV, Dahuofang Reservoir and Songhuahu Reservoir were Grade V, Lao PDRhan Reservoir and Menlou Reservoir were worse than Grade V. The main pollution indicators of these large reservoirs monitored were total nitrogen and total phosphorus. The eutrophiciation of these reservoirs was slight.

Reference: Report on the State of the Environment of China (2003) State Environmental Protection Administration of China