The drinking water crisis in Mianyang, in Southwest China's Sichuan province, caused by the pollution of the Fujiang River by a manganese plant, should be seen as a warning about the lax management of more than 10,000 toxic mine tailings in the country, environmentalists said.

Residents of Mianyang, Sichuan province, line up to get spring water on Thursday. It took two hours for the dripping spring water to fill each bucket. [China Daily]

On Thursday, a week after the river was contaminated by manganese ore residue flooding into it, the southwestern city was still struggling to provide bottled water to more than 200,000 people who rely on the Fujiang River for their drinking water.

Tests on Wednesday morning showed a water sample from the river contained 1.89 milligrams of manganese a liter, while the maximum allowed by the national standard is 0.1 mg a liter.

Lu Liangjun, director of Mianyang's emergency management office, told China Daily it was still unclear when the city will be able to switch back to the Fujiang River for its drinking water.

In the upper stream near Xiaohe village, Songpan county, where the Sichuan Minjiang Electrolytic Manganese Plant is located, a China Daily reporter found ore residue, mixed with rocks and mud, was still piled at the riverside.

The 50-meter tailings dam, a wall built to hold the ore residue, was partly destroyed by a mudslide after heavy rain on July 21, said Liu Minggang, deputy head of Songpan county.

Excavators were removing the toxic residue, some of which is still being carried off by the river, and workers were busy repairing the tailings dam.

Liu estimated that it will still take two or three days to completely remove the residue, the source of the water contamination, meaning the downstream city of Mianyang will be relying on bottled water for several more days.

Torrential rain is predicted for the next two days, posing more challenges for the cleanup.

Local authorities blamed heavy downpours and mudslides for the contamination of the water supply.

Songpan county has become extremely prone to geological disasters, such as mudslides and landslides, after the deadly Wenchuan earthquake in 2008, Liu said.

"But the location of the manganese plant is not in those fragile geological zones, so we didn't expect a mudslide would destroy the tailings dam," he said.

Liu added that such a geological disaster, which also damaged houses and forced 272 residents to be evacuated, was a rare event.

Yang Bowu, director of the work safety department of Songpan county, said a 6-meter-wide rainwater diversion tunnel above the tailings had been completely blocked by rocks and mud. As a result, further downpours led to the collapse of the tailings dam.

However, experts said that lax management of mine tailings and limited capacity to handle emergencies are posing a strong threat to China's already fragile drinking water resources.

Statistics from the Ministry of Environmental Protection show that toxic mining residue now poses increasing threats to the environment and public health.

Since 2006, the ministry has handled 43 emergency pollution cases caused by mine tailings, 10 of which disrupted supplies of drinking water.

There are 12,523 mine tailings in the country, of which 17 percent are in poor or dangerous condition, according to the environmental watchdog.

"About 95 percent of them are small, with limited capacity to deal with emergencies," said a report published on the ministry's website.

Ma Jun, director of the Beijing-based Institute of Public and Environmental Affairs, said mining plants have proliferated as a result of increasing demand for resources and price rises on the international market.

"Most of them are located in distant mountains, where environmental regulation is much looser than in urban areas," said Ma. "The daily discharges from these tailings are already polluting local rivers, but they only attract public attention when major pollution accidents occur."

The tailings, which usually contain heavy metals, are toxic and more dangerous than conventional water pollutants, such as ammonia, nitrogen and phosphorus, said Ma Tianjie, a toxics campaigner with environmental group Greenpeace.

In the case of Mianyang, officials warned that excessive intake of manganese could cause nausea, dizziness, irritability and mood changes.

The Environmental Protection Ministry's report also admitted that most mine tailings were not properly designed and constructed, and investment in safety and pollution-treatment facilities has been inadequate.

"All mining companies are requested by law to review their environmental impact, which includes preparing emergency plans for any accidents. But obviously, such rules are not strictly followed," said Ma Jun.

The Sichuan Minjiang Electrolytic Manganese Plant was relocated to Songpan county from Wenchuan county in 2004 to make way for a reservoir, according to Yang Bowu from the local work safety department.

Before the accident, production at the plant had been suspended for a month as it was undergoing an upgrade to increase its capacity to more than 30,000 tons a year, said Yang.

"The plant will also invite experts to work out a plan to strengthen the tailings dam to avoid future mudslide disasters," he said.

Local authorities defended the government's delay in releasing the pollution information, saying the quality of Mianyang's drinking water only worsened on Monday.

Since the accident occurred on July 21, information was shared among government officials along the Fujiang River, but was kept from the public until July 26, when Mianyang city government issued a notice advising citizens not to drink tap water.

The notice sparked panic buying of bottled water in the city.

An official from Pingwu county, which is located along the river, between Songpan county and Mianyang city, confirmed with China Daily that the local government received information about the pollution.

"But we did not publish the information, as residents in Pingwu county do not rely on the river for their drinking water," said the official, who did not want to be named.

"To be frank, Pingwu county was not completely unaffected by the accident," he said.

Ma Jun, from the Institute of Public and Environmental Affairs, said the delay in publishing crucial environmental information sparked the public panic.

"The local government's mindset has to be changed. They are still clinging to the hope that the pollution can be diluted by continuous rain, and the full scale of the accident can be covered up," Ma said.

"The Bohai oil spill and previous cases showed that prompt disclosure of information to the public is crucial when pollution accidents occur." he said. "But obviously the lessons have not been learned."