The environmental problems along the Nujiang River (Lushui section) are prominent due to the loss of sewage and garbage pipes

The environmental problems along the Nujiang River (Lushui section) are prominent due to the loss of sewage and garbage pipes

Source: Yunnan Provincial Department of Ecology and Environment

In June 2023, the second round of the second batch of the third ecological environmental protection inspection team in Yunnan Province found that the sewage and garbage in Lushui City were out of control, the urban and rural domestic sewage was directly discharged, the domestic garbage was burned in the open air, Construction waste was dumped at will, and the environmental problems along the Nujiang River (Lushui Section) were prominent.

1、 Basic information

As one of the six major water systems in Yunnan, the Lushui section of the Nujiang River is about 120 kilometers long and classified as Class II in terms of water function. The "Three Year Action Plan for Improving the Environment of the Nujiang Grand Canyon (2022-2024)" issued by the Nujiang Prefecture Committee and Government clearly requires that the treatment rate of domestic sewage in non Chengguan towns reach over 70%, and the harmless treatment rate of sewage and domestic waste in townships reach 100% and 80%, respectively. However, the inspector believes that there is blind optimism and a weak sense of urgency in maintaining stable water environment quality and achieving work goals and tasks in the Nujiang River.

2、 Main issues

（1） Lack of daily maintenance of sewage pipe network and prominent direct discharge of urban domestic sewage

The site inspector found that the sewage pipes in Bajiao River, Laimao River, Xiaoshaba River and other rivers in the urban area of Lushui City, Nujiang Prefecture were damaged, the daily inspection and maintenance were not in place, the sewage overflowed to the river through the damaged area, and the mixed sewage was directly discharged into Nujiang River.

For example, more than 31 of the 41 sewage pipes within 285 meters of the Bajiao River estuary were damaged, and the sewage overflowed to the river through the damaged area. The Chemical oxygen demand, five-day Biochemical oxygen demand, and ammonia nitrogen concentrations of the sewage at the direct outlet reached 116, 20.6, and 6.9 mg/L, respectively, exceeding 6.73, 3.12, and 12.8 times the Class II standard for surface water.

（2） The effectiveness of the inspection and rectification has not yet been demonstrated, and the domestic sewage treatment capacity is insufficient. The sewage flows directly into the Nujiang River.

In 2021, the feedback of the second round of ecological environmental protection supervision by the central government pointed out that the collection rate of urban domestic sewage in Lushui City was seriously low. By the time the inspectors arrived, the effect of supervision and rectification had not yet appeared, and the domestic sewage collection and treatment capacity was still insufficient. It is estimated that the daily water supply of the two waterworks in Lushui City is about 30000 m3, the daily domestic sewage production is 23700 m3, and the actual daily treatment capacity is only 13000 m3, resulting in about 11000 m3 of domestic sewage flowing directly into Nujiang River without treatment.

（3） Emphasizing construction and neglecting management, existing domestic sewage treatment facilities have been built but not used, becoming mere decoration.

The pollution control work in Lushui City is not effective. Although sewage treatment facilities have been built in Gudeng Township, Chengan Township and other towns and townships along the Nujiang River (Lushui section), the on-site inspectors found that they were basically idle and did not work. During the unannounced visit, they found that they were unattended and did not operate, which reduced them to a "sunning" project in the daytime and "reflecting the moon" project at night. In addition, the domestic sewage pipeline network in the town is severely blocked and damaged, and a large amount of domestic sewage is directly discharged into the Nujiang River through rainwater ditches. The sewage in the ditches flows horizontally and has a pungent odor.

（4） Shangjiang Town should have no built domestic sewage treatment facilities, and domestic sewage should be concentrated and directly discharged into the Nujiang River.

Shangjiang Town, Lushui City should plan to build a centralized sewage treatment plant to collect and treat the sewage from Shangjiang Town, Xinjian Village and other villages and towns. However, as of the time of the inspection, there was no domestic sewage treatment facilities in this area except for the pipe network. All domestic sewage was directly discharged into Nujiang River through the collection pipe network through simple open channels, cover ditches and agricultural irrigation ditches. The water quality monitoring data shows that the Chemical oxygen demand in the mixed water in the flood control ditch near Wanxiao in Shangjiang Town is up to 620mg/L, and the total nitrogen is 31.8mg/L, respectively 40 and 62 times higher than the Class II standard in the Environmental Quality Standard for Surface Water (GB3838-2002).

In addition, the problem of random dumping of domestic and Construction waste along the river occurred from time to time. The on-site inspector found that the random dumping of domestic and Construction waste and other solid wastes along the banks of the Nujiang River in the Shangjiang Town section fell into the river channel, eroding the river channel, polluting the water environment, posing a threat to the water quality, and the requirement of 80% harmless treatment rate of township domestic waste was not met.

3、 Cause analysis

The inspection team will further investigate and verify the relevant situation, and carry out follow-up inspection work as required.