[pilom]

A pipeline like this is so naive I can't figure out if the op is serious or not. The cost alone would bankrupt multiple states. For example the Central Arizona Pipeline goes from lake Mead to Tucson. That's it. It cost on the order of $10 billion and provides barely enough water to cover the needs of the cities and farmers along it. Doing a pipeline from Iowa over the continental divide and into the Colorado River basin that was big enough to matter would cost hundreds of billions to a trillion dollars.

Forcing water intensive ag to move by actually charging a reasonable rate for water is a far more sensible answer. Just requires political capital.