Why is the water quality in Lincang so bad?

The reasons for the poor water quality in Lincang include the lag in demarcating drinking water source protection zones, rural domestic pollution, and agricultural non-point source pollution. According to relevant information, Lincang is located in the southwest of Yunnan Province and on the bank of the Lancang River. It is named because it is close to the Lancang River. The city has jurisdiction over 7 counties and 1 district, 77 towns and villages, and 73 centralized drinking water sources in towns and villages, with a water intake of 16.3473 million m/a and a serving population of 302,500. According to the monitoring results of Lincang City Environmental Monitoring Station on drinking water sources in 8 typical townships (towns) in 7 counties and 1 district in the city (water intake 6.1394 million m/a, service population 74,700), it can be seen that only the Qingshui River in Zhenkang County The water quality of the three drinking water sources, Fushushan River in Fengqing County and Daogeng Reservoir in Yun County meets the Class II~Sichuan standards in the "Surface Water Environmental Quality Standard" (GB3838-2002) and meets the requirements for centralized drinking water sources. Others All five are Category IV and V, which can no longer meet the requirements for centralized drinking water sources. The main factors exceeding the standard are total phosphorus, total nitrogen and nitrate. Among the five drinking water sources that exceed the standard, the water quality of the Sancha River water source in Shuangjiang County and the Bangmu River water source in Gengma County has worsened in recent years, and the current water quality is Class V. In addition, the monitoring results of 10 main drinking water source reservoirs in 7 counties under the jurisdiction and 10 main drinking water source rivers in Linxiang District also show that some rivers and reservoirs (such as the Xiayongquan River in Linxiang District and Shuangjiang Laileng Reservoir) ) The water quality is below the standard and cannot meet the requirements of centralized drinking water sources. The main factor exceeding the standard is iron. Among them, the maximum exceedance ratio of Xiayongquan River in Linxiang District was 15.95 times.