Unfortunately, it is now clear that on 21st July another tailings dam failure occurred in China, again with serious effects.  Adrian Moon has very kindly provided the following description:

There has been a major release of tailings from the Xichuan Minjiang Electrolytic Manganese Plant in the Aba Tibetan and Qiang autonomous prefecture. Accounts are here and here and there are others. Photographs can be found here, video here. The plant is somewhere on the Fujiang river upstream of Mianyang (31°28’48.77″N 104°44’30.03″E). Unfortunately the Google Earth images for most of the Fujiang river between Mianyang and its confluence with another river at (32°30’41.44″N 103°38’22.45″E) are of poor quality and I have not identified a mine site upstream, although I may have overlooked it.

I have not seen what caused the polluted water to be released although some form of storage pond or dam failure seems likely. There was a manganese ore tailings dam failure in Hunan in 2009. The most spectacular tailings dam failure recently was that of the Kolontar bauxite mine in Hungary last year which sent a river of toxic red sludge into the town.

For mining, contamination risk and tailings dam failure threat near Lhasa see the paper: Xiang Huang, Mika Sillanpää, Egil T. Gjessing, Sirpa Peräniemi, Rolf D. Vogt, Environmental impact of mining activities on the surface water quality in Tibet: Gyama valley, Science of The Total Environment, 2010, <http://www.google.com/url?sa=t&source=web&cd=1&sqi=2&ved=0CBgQFjAA&url=http%3A%2F%2Ffolk.uio.no%2Frvogt%2FCV%2FCo-author%2FSTOTEN-D-09-02146-1.pdf&ei=rskxTuf6IoqSswbHlrDpBg&usg=AFQjCNGJ97Xm3wrBxAZu2W1-MDhmlrTEhQ >.

The acute issue on this occasion is clearly pollution of the watercourses.  The chronic problem is that China is suffering far too many failures of this type.  Urgent action is needed before there is a an event that results in very substantial loss of life,