The EPA administrator turned to semantics in the Trump administration’s latest move to undermine Obama-era environmental policy.

The Clean Water Act, which dates to 1972, protects the “waters of the United States.” WOTUS is basically the government’s attempt to define what comprises the national water system. Problem is: No one knows exactly what waters are included.

The distinction seems clear when you look at extremes (the Mississippi is, a puddle is not), but what about raging whitewater that kayakers bounce down in spring, but goes dry in the summer? There are 2 million miles of these intermittent streams in the continental U.S., and they exist in a legal grey zone and have a huge effect on the country’s water quality.

Obama tried…