When you say "No hard tasks" I assume you mean that the engineering is relatively straightforward.

The surface of Lake Michigan is around 650 feet above sea level. Go 50 miles due west and you are at 800-900 feet elevation. The average elevation in Kansas is around 2000 feet above sea level! If you go southwest, it is naturally downhill - the existing rivers prove that - but you run into the problem that the water is heading south more than it is heading west.

It's a serious uphill climb to get that water out west. You don't need a sloped canal, you need a sloped tunnel thousands of feet below the surface!

We are familiar with pipes, pumps, siphons, canals. etc. It is engineering of a routine, but massive scale to perform a major shift like this. The question is cost? Water can be pumped with solar/wind energy. With major area on their way to become parched deserts - except for water. What is the Value of all California crops every year - that can go to zero every year versus the one time cost of a major water project = a spend once, plus maintain = get a permanent 'annual California crop every year' Water project, by their nature are long lived and low maintenance.

With how quickly, on-time, and within-budget California is managing to build the few-hundred miles of its touted High-Speed Rail system - that "no hard tasks" engineering project might take a century or few to become operational.

Also, you note "water added to the west would revive it from the death spiral it is now in". Ah... 100% of the average discharge rate from the entire Great Lakes system - including Lake Ontario, elevation ~400' below the other lakes - is only about 2/3 of the discharge capacity of just the Hoover Dam spillway. I'm thinking you'll need to divert the Amazon River (~25X the discharge of the Great Lakes) to meet the need.

I am not sure of your Hoover discharge figures. St Lawrence is about 17,000 cubic meters per second. Hoover is far far smaller about 3,300 cubic meters per second. St Lawrence is over 5 times as large. You may have mixed up cubic meters/feet?

At least from Wikipedia's numbers, 17K m3/sec. average flow in the St. Lawrence is only found below the mouth of the Saguenay River - far downstream from the Great Lakes, effectively at sea level (vs. even Lake Ontario is ~70m higher), and (from other sources) well downstream of the point where substantial tides and salt water intrude from the Atlantic.

I used the spillway capacity of Hoover Dam, rather than try to add up the total (diverted & un-diverted) flows of the Colorado, Columbia, Missouri, Rio Grande, Arkansas, Red, Sacramento, etc., etc. The point being that 10-20% of the Great Lakes water flow would be far, far too little to revive the west from its death spiral (to paraphrase user aurizon).

Well, the flow varies as you reach the source, being about 7,000 M3/sec as it exits Lake Ontario. In any event, my intent is to have a tolerable degree of outflow diverted from the great lakes, esp in flood years during the melt, when many downstream areas are flooded when the melt is compressed in time by 2 hot spring weeks. Aquifers can be recharged at many permeable perimeters points and the Ogallala aquifer https://en.wikipedia.org/wiki/Ogallala_Aquifer Has a number of places in it's East and North East that can be used as recharge areas. As you see from the wiki, it has been drawn down for decades. Canadians are full of 'not one drop' fanatics - who would prefer to see it go to the Atlantic - flooding each spring, along the way - instead of helping the US drought. My feeling is the peak snow melt could be diverted to the South and West towards suitable recharge points to mitigate this drawdown - it will take years to build and years to work, but in the end it needs to be done. The forces of warming climates over the next 50 years could make the great plains into the Great US central desert - where nothing either lives or grow. It is a bleak prospect, but we screwed the earth and we must live through it - one way or another - wetter is better.