acres. Let's see, 161,000 times 2200 feet up times 1.2 kWh divided by 67% efficiency in pumping =
539,229,850 kWh to raise Lake Powell by 1 foot with water from the headwaters (not exactly the spot where the Mississippi has the most amount of water) of the Mississippi.
You would need 23 full size nuclear power plants to power enough pumps to raise Lake Powell 1 foot over the course of a day.