How often do we have massive milk spills in the US?
I've been responsible for about a 1500 gallon spill, and I've seen plenty of milk tankers wreck and spill. It smells bad, and yes it can kill fish, but unlike an oil spill, after a couple of weeks, the environment springs back just fine. Cleanup is also much easier, since you just have to gather the milk and/or contaminated soil, and contain it somewhere for a few weeks. In most cases, for a tanker spill, they just dam up the ditches, pump the loose milk to another tanker for disposal, and let the soaked soil sit for a month or so before they reopen the ditch.