Interesting Q&A on their webpage.  Here's one that might apply to many:

Which Waters Are Federally Controlled?

Waters on which vessels must observe federal requirements, including VDS requirements; these waters include:

• Coastal waters
• The Great Lakes (Lake Michigan and Lake Superior)
• Territorial seas
• Bodies of water connected directly to one of the above, up to a point where the body of water is less than two miles wide, including the Mississippi River, and portions of the Wisconsin, St. Croix, Wolf, and Fox Rivers
• 
  
• 
  
• 
  
• So quite a bit of waters in Wisconsin but if you only do small inland lakes your ok.

 Fish

That's the way I understood it

Stitzo, I haven't looked at the law yet in detail, but doesn't it say somewhere in the law that all new boat/motors after 2020 must have the kill switch, but that you must use the kill switch if your motor already has one?  My 2000 Mercury 50 HP, for example, has a kill switch on it.  I know cause I spent 15 minutes one day trying to start my motor, then realized my son got in my boat and played with it, flicking the switch down to off! I didn't have the little curly rope attached to it at the time though.  But anyhow, my understanding is this, as of now, only applies to federal waters anyway, so for now, except when I use my boat on the Wolf River I won't worry about using it.

This has nothing to do with Wisconsin law get your stuff straight or dont post lies

Pimply the article you site is from the coast Guard.  They have jurisdiction on federal waters not state waters.  So technically they were factual and correct.  

If you read the boating regs similar laws apply to other required equipment such as an airhorn on the same federal waters but not on state waters.  It is confusing since no reg pamphlet or publication claims that the law is enforced by only certain types of officers and will be ignored by other types of officers. 

Yeah, I had to peel back the same onion layers that oncebitten did in order to find the grandfather clausing. Ridiculous. 

All the various “reporting” of it makes it sound like it’s pretty much a Chicken Little one size fits all situation. Shoot, unless I missed something, even the USCG page doesn’t address it as only being applicable to craft BUILT after 1-1-20, until you get to the Q&A #9. 

Ridiculous. Law goes into effect 4-1-21. Only pertains to units built after 1-1-20. And it’s reporting is just very partial and limited truth that creates confusion & consternation for a whole lot of folks. 

PimplySwede 

Thanks for the website search.

I scrolled down to the 

Engine cut-off switch-FAQ

And got the answers to these questions,   for me at least

From BoatUS.

The new law applies to all federally navigable waterways. As this is a federal law, states do not have the ability to enforce the new ECOS regulation — though seven states (Alabama, Arkansas, Illinois, Louisiana, Nevada, New Jersey and Texas) currently have their own ECOS laws. BoatUS expects most states to amend their regulations to match federal law over the coming years. While boat operators who fail to follow the new requirement could face a $100 civil penalty for the first offense, BoatUS expects the U.S. Coast Guard’s initial focus will be education. 

Basically after reading multiple reports on this.  If the coast guard is on navigable waters they could enforce the law.   As of now if you are not on coast guard jurisdiction "federal waters" it can not be enforced until there is an applicable state law.  And honestly the only time it applies is if you are on plane.  Probably not that easy to observer either way at that point.   All in all nothing to get very excited about after reviewing.   

Simple test is will the WI DNR enforce.  They have already indicated this is a CG job.  Kind of a nothing burger after you think about it.

Bronz... read the post below yours.