Just wait until they drain The Great Lakes. That would be the quickest way to starve out the entire population of the USA. Canada, too.
Luckily, people were smart enough to devise The Great Lakes Compact - but that doesn’t mean that Socialists will stop trying to drain them! Surprised that CA and the Desert Southwest haven’t been building vast pipelines to do so!
https://greatlakes.org/campaigns/defending-the-great-lakes-compact/
You can’t drain the Great Lakes the outlet river beds are shallower in depth by hundreds of feet vs the deep center water bodies. Those are glacial lakes where the water is melt water from the miles thick ice that used to be filling those holes. The rivers between them are modern overflow features made by natural overflow on the last 12,000 years. In theory you could sink submersible pumps into the deeps and pump water out but even ten meter diameter pipes about the largest that can be made would only flow 6 million acrefeet per year and you would need a half dozen nuclear reactors running 24/7/365 at max output to pump the water up hill out of the glacial basins. So no it’s not possible to drain the lakes sleep well. You could at most take the top 100 feet then you have to pump against gravity the other 1800+ feet of water depth. The flow of the saint Laurence River is outflow and overflow from the lakes think about the size and volume of that flow that’s how much surplus water those lakes get every year via rainfall and snowmelt in the HUGE capture area of the Great Lakes region.
You could take 10 million acrefeet per year and send it down the Chicago River to the Mississippi River system and not make a dent in the st Laurence River outflows most years. Capture that extra flow at Cairo Ohio and send it via two ten meter wide pipes up hill to Denver 860 miles away and 5200 feet up hill. You need six 1000 megawatt reactors to move that much water uphill. It would cost 400 billion and solve the water crisis in the southwest forever. Denver already has tunnels through the continental divide reverse the flow and the water hits the Colorado basin and flows downhill via gravity all the way to Mexico. Yes I am a hydro geologist and have done the math and used ARCGIS to model this very project for the USGS. For less than what we are giving to the corrupt Ukes we could double the average flow of the Colorado River forever.