It seems more and more likely the next Great War will be fought over water.

As a Canadian, I get nervous when I see the US running out.

The US is nowhere near running out. Big Ag might have to cut back on growing thirsty crops in the middle of the deserts, though.

One of the great lakes alone (Ontario) contains enough fresh water that it could supply the lifetime water requirements of 28 billion people.

Wars will be fought over water, but of all the foolish reasons the US could invade Canada over, water isn't one of them. The US has ample shoreline on every Great Lake, and essentially none of the Mississippi watershed lies north of the border.

First it is only the South West area of the US, East of the Mississippi river and the Northwest has plenty of water.

It is the fact that everyone wants to live and companies are moving to a desert that is causing the problem.

https://worldpopulationreview.com/country-rankings/fresh-wat...

You have nearly 10 times the freshwater per capita compared to the US. How selfish /s.

Let's thinks of a casus belli. How about something like: "Trillions of gallons of fresh water flow uselessly into the frozen northern seas every year due to Canadian inaction. We are stepping in to build the infrastructure needed to save that water and feed the continent. "