From Modern Farmer's fascinating story about how to deal with the whey problem:

"For every three or four ounces of milk, Chobani and other companies can produce only one ounce of creamy Greek yogurt. The rest becomes acid whey. It’s a thin, runny waste product that can’t simply be dumped. Not only would that be illegal, but whey decomposition is toxic to the natural environment, robbing oxygen from streams and rivers. That could turn a waterway into what one expert calls a 'dead sea,' destroying aquatic life over potentially large areas. Spills of cheese whey, a cousin of Greek yogurt whey, have killed tens of thousands of fish around the country in recent years."