It is obvious. Since the Chinese population is becoming more capitalistic, their government decided to put on a demonstration in order to emphasis their communist form of government. What better symbolism than turning a river red? Soon you'll see the return of the little red books, red flags, red-eye flights, and an abundance of red fruits and vegetables. Can a rhubarb festival be far off?

Didn't the Rouge in Michigan have the same phenomenon from dumping about 70 or so years ago?

Paper plants use all kinds of fun hazmat, and who knows what they're using for the red food coloring? Depending (notice the residents detected a "smell") on what's in that water, I wouldn't eat a fish caught in it. IIRC... Some sulfur compounds combine with Mercury and turn red. Since paper mills use sulfuric acid, well...

Who knows what evil lurks in the hearts of rivers of China...

Okay....there's a food coloring company and a clothing manufacturer (which may work with dies) upstream. I wonder who "dumped".

Then again....it may have been a protest. John Galt may well have walked off the line at the food coloring factory.

I also read the comments: like the one about frogs and locusts.

Holy Moses!

Moses... you silly boy.

The catching of fish was before the sudden color change. Someone definitely dumped illegally.