The rule defines eight categories of waters of the U.S. Six categories include traditional navigable waters, interstate waters, territorial seas (these three are called “jurisdictional waters”), impoundments of jurisdictional waters, “tributaries,” and “adjacent” waters. These are jurisdictional by rule in all cases, requiring no additional analysis in order to be regulated. To be adjacent, the rule uses the rubric of “neighboring,” which can be met by waters in the 100-year floodplain—meaning land which might be wet one out of every 100 days is a water of the U.S. and can be federally controlled. Texas coastal prairie wetlands are another type...