Why tunnels, not canals? Particularly in the case of Denver, you've got a huge elevation gain, so you'd need the locks anyway, and digging tunnels is expensive (and buying farmland to put your canal through is relatively cheap).
Tentatively-- in hot dry country, a tunnel loses less water to evaporation.
This thread is intended to provide a space for 'crazy' ideas. Ideas that spontaneously come to mind (and feel great), ideas you long wanted to tell but never found the place and time for and also for ideas you think should be obvious and simple - but nobody ever mentions them.
This thread itself is such an idea. Or rather the tangent of such an idea which I post below as a seed for this thread.
Rules for this thread:
If this should become a regular thread I suggest the following :