Oh, and let's not forget that large parts of Oregon were still in fairly good environmental conditions. The pacific northwest was polluted, sure, but not to the extent the east coast was. Combined with Crater Lake's significance, and geographic features that made for good defense, it was a good choice. Especially since with everyone's eyes on Denver, they could do the 'out of sight, out of mind' routine.
In other connections, I was rereading the old SOTA books, and came across a mention of a the Sagan Zaba (White Rock) on Olkahon Island. Supposedly haunted area, where a cave is supposed to have suddenly appeared, with evidence of habitation going back thousands of years. Remind anyone of the Deep Lacuna?