The national environment watchdog has started a probe into the alleged illegal discharge of untreated sewage and toxic waste into a river and lake in Xinyu city, Jiangxi province.
The Ministry of Environmental Protection said on Thursday that it believes Yichun Zhong'an Industrial Co, a chemical plant, discharged the pollutants on April 3.
The waste that spewed into Yuanhe River, which links to Xiannyu Lake, contained toxic chemicals including arsenic, thallium and cadmium.
The lake is the city's water source.
The city immediately stopped using water from the contaminated lake and only resumed on April 10, the ministry said.
The city switched to using backup water sources from other regions to guarantee a stable supply for residents and monitoring of the contaminated lake now shows water quality is back to acceptable levels, it said.
Now, the ministry wants to find out what happened and who was responsible.
The incident happened after the plant was ordered to suspend production in March, the provincial environmental authority said. The plant is believed to have illegally continued to produce chemical products and waste products. It is suspected of disposing of waste through a 2.5 kilometer hidden pipe, the provincial environmental watchdog said.
Waste in the pipe was found to have alarmingly high levels of poisonous cadmium that were 46,550 times the national safety standards, it said.
The authorities have sealed the factory and removed the sewage pipe.
In light of the seriousness of the incident, the ministry listed it as a major environmental emergency, the second highest level in the four-tier system, and started the investigation to clarify who was responsible for the discharge among the management of the plant and the local government.
The ministry expects to finish its investigation within 60 days.
Recently, water pollution from industrial production has grown to become a major concern. Two of the three major environmental emergencies in 2015 in China were similar cases, according to the ministry's data.
On Nov 23, a tailings pond at a mineral plant in Gansu province leaked and contaminated 344 kilometers of rivers in Gansu and neighboring provinces.
On March 26, a pharmaceutical factory in Xinhe county, Xingtai city, Hebei province, discharged toxic waste into the urban water supply network, making 81 residents sick and leading to a three-hour cut off of water supply for the whole county.
In 2015, China had 330 environmental emergencies, which was down 141 cases on 2014, the ministry said, adding that, among them, three were major events.
