The More Things Change . . . . The Most Recent Clean Water Act Confusion

Just a few years ago, before the Trump Administration EPA revoked and replaced the Obama Administration EPA's regulations determining the reach of the Clean Water Act, the Obama Administration EPA regulations were the law in half of the United States and the Clean Water Act itself as it had been interpreted by various Federal Courts as well as by EPA and the Army Corps of Engineers in guidance memoranda, but not regulations, was the law in the other half of the United States.

Why did we not have one Federal law that applied from sea to shining sea?  Because some but not all Federal Courts had struck down the Obama Administration EPA's regulations which remained effective except where Federal Judges had determined otherwise.