It's all about "control".

EPA Deletes ‘Navigable’ From Statute – States Sue

Washington, DC –-( Twenty-nine states, more than half the stars on the American flag, have filed lawsuits against the U.S. Environmental Protection Agency for redefining the “Waters of the United States,” or WOTUS.

EPA rewrote the law, erasing “navigable” and usurping states’ rights by including local seasonal streams, farm irrigation ponds, roadside ditches, and even “connective” dry lands placed under authority of the Clean Water Act.