home.disney.go.com / HQ: Lake Buena Vista, FL
How many different ways can you get water from a lake at the foot of a mountain, up to the top of the mountain?
You don't really need to worry about it, because nature does it anyway. When water in the lake evaporates into the air, it forms cloud, then rains... yeah you know the story.
Pumpit, carry it, by will of God.
The easiest way would be to just pump it, but the variable costs of that can add up quickly over the long-term. The cheapest way I can think of is to create some sort of a siphon that runs from the lake, over the top of the mountain, and back down to a different spot that's lower than the lake. If you set it up right, you could drain a small amount of water at the mountain top and the siphon would still work.