[penneyd]

If these folks didn't use the water, what alternate use would it be put to?

[SrslyJosh]

Not draining the entire Colorado River dry.

Edit: Downvote this if you like, but what is your plan for providing water to the people who depend on the Colorado River once the farmers have completely emptied the reservoirs it feeds?

[davidw]

Healthy fluvial ecosystems? Growing food that can be directly consumed by people?

[LikesPwsh]

http://www.climate.gov/news-features/featured-images/groundw...

"Aquifer depletion" is worth searching if you want to read in detail.