Yeah. This blog post spends a lot of words on the idea of large-scale desalination, but it's closer to a child's blueprint of a spaceship than even a rough proposal for a viable engineering project.
The Carlsbad Desalination Plant near San Diego was completed a few years ago and is now operational. It is the largest, most technologically-advanced and energy-efficient desalination plant in the United States. It is approximately the best we can do right now for large-scale desalination.
It cost about $1 billion to construct, about $50 million per year to operate, and produces about 150 acre-feet of fresh water per day.
"Stage 1" from this blog post proposes to produce multiple millions of acre-feet of freshwater.
All of the costs in the blog post are off by a couple orders of magnitude.