Over the years, any number of freepers have thought up a variety of ways to deal with the river and access to it. If we can figure it out, I am quite certain that actual engineers can do the job. They figured out how to get to the moon, they figured out how to dam the Colorado (on which I live) and this corner of AZ is a maze of irrigation waterways.
We can do it if we want to do it. I don’t care how many thousand miles it is. I don’t care about terrain. We build interstates THROUGH mountains of solid rock. We run physical cable across oceans. We steer drills thousands of feet underground. We can figure this out in short order and make it happen.
All true.
But still.. a simple fence isn’t workable.