When President Trump started his tenure he promised to repeal something called the ‘Waters of the U.S.’ rule. And this week he made good on that promise.

The revised definition of “Waters of the United States” eliminates protections for half of the nations wetlands and nearly a fifth of streams.

On this episode, we spoke with Ariel Wittenberg, who covers the Clean Water Act for E&E News, about the major changes to the Obama-era rule and their implications.