The water going through that area is raise more than 2000 feet before going through those tunnels. You can see some of it off to your right when heading North on I5 just past Castaic lake. I am always amazed at home much water they move around there.
You are right about them using alot of energy to move water around, the SWP is the largest user of energy in the state. (It also happens to generate alot of energy too)

I havent quite figured it all out for myself just yet, esmith, care to help me understand the slide just after the one you reference about 3000kwh for water to LA. It says 6900kwh for San Diego, but it calls it energy intensity, which I have not had time to wrap my head around. At first glance it looks like an acre foot of water to San Diego is something more like 6000kwh/ac foot.