The 9+ billion farmed animals in the US combine to produce an unimaginable amount of fecal waste – most of it coming from massive industrial animal prisons, commonly called Concentrated Animal Feeding Operations (CAFOs). All of it has to end up someplace, and sadly, a huge amount of it ends up in our lakes, rivers, wetlands and oceans where it poisons fish, creates massive toxic algae blooms and renders vast amounts of water unsafe for drinking or recreation. Thanks to a lot of underhanded dealings, these CAFOs have been allowed to avoid most environmental restrictions. But now, a judge has ruled that all CAFOs will need to comply with environmental impact assessments in order to access government loans (which most of them need, since it's such an unsustainable business model). And in a separate ruling, the US Environmental Protection Agency (EPA), after years of pressure from various advocacy groups, has finally decided to force all CAFOs to comply with the Clean Water Act (which most currently do not). This will likely raise the price of meat and help clean up a lot of vital waterways.
Our sources for this meme are Civil Eats (for the new rulings) and PIRG (for the largest polluter statistic)