Below is an article by Radio Free Asia:

Polluted water from a Chinese mining site in a Tibetan-populated area in western China’s Sichuan province has spilled into a nearby river, killing large numbers of fish and livestock owned by villagers, according to sources in the region.

The spill last week in the Kardze (in Chinese, Ganzi) Tibetan Autonomous Prefecture’s Dartsedo (Kangding) county has also fouled the water sources of people living in the area, a local resident told RFA’s Tibetan Service in an e-mail on Thursday.

“On or around Oct. 13, contaminated water from a mining site at Balang township overflowed into a 20-30 mile stretch of the river, resulting in the deaths of countless numbers of fish and other animals,” including horses, sheep, and goats, RFA’s source said.

“The spill has also contaminated the drinking water of five to six villages,” he said.

“People from the villages are complaining to the Chinese authorities, but in response the officials are sending troops into the area. Locals believe the Chinese are mining lead in the area,” the source added.

Separately, a second source told RFA that county officials had also arrived at the site of the disaster.

“They have assured the local people that higher-ups will resolve the issue,” he said.

Mining had begun in the area in 2005 under the pretext of “road construction,” one source said, adding that local village leaders had argued against the construction but were warned by county officials and builders that their objections conflicted with “the will of [the ruling Chinese Communist] Party and county planners.”

“Locals have been warned that protests against such projects will draw severe consequences,” the source said.

A similar spill in 2011 had also killed livestock belonging to Balang township, but “complaints to Chinese authorities yielded no results then, either,” he said.

“Local Tibetans have the responsibility to stop this mining,” he said. “It is legal to protest against environmental destruction.”

Following last week's water spill, Tibetan villagers carried large quantities of dead fish to township government offices and demanded that officials take action to curb the pollution, a third source told RFA's Mandarin Service, speaking on condition of anonymity.

"But the government just sent in troops to tighten control."

"Starting from Oct. 14, all cell phone and Internet communications have been cut off in the area," the source said.

"Government officials who inspected the polluted area responded only that it will 'take time' to investigate the situation," he added.

"The Tibetan protesters are very disappointed because the mining operations are still going on, and the contamination problem remains unresolved."

Mining operations in Tibetan regions have led to frequent standoffs with Tibetans who accuse Chinese firms of disrupting sites of spiritual significance and polluting the environment as they extract local wealth.

In August, clashes between police and Tibetan protesters at Chinese mining sites in neighboring Qinghai province left dozens injured and several detained.

Meanwhile, in January, Tibetan sources told RFA that Chinese-operated mines in Lhundrub county near the Tibet’s regional capital Lhasa had caused “severe” damage to local forests, grasslands, and drinking water.

Waste from the mines, in operation since 2005, had been “dumped in the local river, and mining activities have polluted the air,” one source said.