But the highest elevation is 7,000 feet.
https://www.flattestroute.com/Laurel-MS-to-Las-Vegas
I know the start point is not where the plan says it should be, but that part is irrelevant. There are mountains between the two places. And that is a lot of feet to move water.
Actually, the mountains are good. CAP cleverly uses mountain ranges to run water around them, so the water can go downslope for a long distance. Not that many pump stations required!
In flat they would have to somehow pile up on one side and dig in on the other side.