Four foot pipeline wouldn't mean much, I'm afraid. Shatner ought to stick to making movies and commercials.

Three huge pipes go over the mountains after leaving the Colorado River. They feed part of the water needs for LA and San Diego. I've posted some far off pics of them but this page has more facts and figures on the Colorado River Aqueduct project.

http://larrybergerphotography.com/2012/water-works/

That little project transports about one billion gallons / day. From the same reservoir, is drawn another 1.5 billion gallons / day to supply Phoenix, Tucson, and some agriculture along the way. There is still a significant flow in the Colorado River, below the Parker Dam and that makes its way south to Yuma and waters a considerable stretch of farmland along its way. Still some that makes its way to Mexico after the Imperial Dam that is responsible for watering farms in the Imperial Valley.

What I've seen, water is precious here and wisely used. A lot of it is used many times over before is finally ends up being used to water crops and feed our country and Mexico.