This is one of those issues where, in my opinion, the past court took a distinct track away from the limits of the enumerated powers of the Constitution.
It all started out with the English concept of Royal rivers - those areas influenced by the tide and usefull for navigation and ports. The King reserved control over these areas. In England, these were all close to the coasts. When the idea of royal rivers was imported into America, rivers ran far inland to the Great Lakes. Originally there was a minimum ship size measured by draft. The court interpreted federal jurisdiction as applying over interstate navigable rivers that had to have two points in separate states that could be navigated for commercial purposes - e.g. interstate navigable rivers. The federal government NEVER had jurisdiction over intrastate rivers.
The court expanded navigation to include small boats on streams. It then took jurisdiction over hydropower dams that blocked navigation on interstate streams. Then it took charge of water quality AS AFFECTED NAVIGATION on interstate rivers - particularly dredge and fill. Of course, this eventually became expanded to include water quality elements having no perceivable impact on navigation, such as low dissolved oxygen, water temperature, etc.
Traditionally, all streams not commercially navigable between states were under state jurisdiction. Then the jurisdiction over federal interstate navigable streams was expanded to include navigable and non-navigable streams that empty into interstate navigable streams as "waters of the United States." As wetlands can be hydrologically connected to streams, this was expanded to include wetlands.
Following that track, groundwater is hydrologically connected to streams, leading to the Safe Drinking Water Act, etc.
It is like an octopus with tentacles reaching out to embrace everything it can. It all comes back to this - what relationship does the quality of my well water or the fill of a wetland on my property have to do with interstate navigation? Proximate cause dictates that there be some direct cause and effect relationship proveable between my use and substantial negative impact on navigation. I don't see it and the "cummulative effects" arguement obscures the standard of proof required under proximate cause.
Only 7 or 8 posts on these two threads...Maybe they are read, but not understood...
"It is like an octopus with tentacles reaching out to embrace everything it can."
That's a pretty good description of our beloved Federal government itself.