That is a whataboutism.

This isn't about China or the size of the lake, but the fact that there is a lake because the effluent is difficult to dispose of and currently has no use.

Edit: to further clarify, I am not against refining them in the USA. Just that we have to also address the consequences of doing so.

"Difficult to dispose of and has no use" is the very definition of a tailings pond, and you'll find them all over the place if you care to look. Environmental catastrophies are happening all over the globe on a massive scale. My point is exactly that; yeah it's toxic, but so is basically every mine and many oil refineries too. Check out the rate of cancer around coal mines or refining hubs, you might be surprised.