Regulating the TH has from little to no correlation to regulating the backcountry use after the first fork in the trail.
No, actually. That's exactly what the models applied to TH quotas do (or, ok, are supposed to do). It's like any dispersal model: disease, ants, whatever. You know there will likely be a statistically predictable dispersal of a population from point x. They actually seem to work pretty well, though maybe I'm just used to and accepting of the results. The quotas now are based on modeling from the mid 70s, so there's a strong argument they should be done again.
EDIT: hmmm. Let me expand on that a little more. I wouldn't agree that after the first fork, that there's little or no correlation, but that the numbers reduce so much that the impact (both social and ecological) is much less important. However, there are nexus (ok. What's the plural of nexus??) -- places where trails come together that tend to be destinations like Crabtree area -- that receive use from so many trailhead inputs (JMT from Happy Isles; Onion Valley; Rock Creek; Lodgepole on HST) that they are not accurately predicted or controlled by trailhead quotas. Or, at least, not from the original models.
Edit continued: But the other thing is that the models were done in the 70s -- at the absolute peak of visitor use in the Sierra. It decreased dramatically by the 90s and, I think, is now relatively stable. Which is to say that visitation isn't a huge problem in terms of impact. This is beginning to worry be about these Alternatives. That they are addressing a problem that is really not there by either current or future projections.
And restricting camping close in to a trailhead -- even assigning campsites -- is commonly done.
So the answer to why should a JMT through hiker be subject to the same quota as a destination hiker (e.g. to LYV). It's because they're all estimated into the dispersal from point x. LYV, for instance, has a maximum carrying capacity per night. Everyone who leaves the trailhead is part of that, even though some continue on either on Day 1 or on Day 2.
The Travel Zones used by both Yosemite & Sequoia Kings were begun to track use by zones and, I think, ground truth the models. But I don't think they've been compiled in years (could be wrong on that, though...). The problem I have with the zones apparently proposed by the WSP is they're huge. A zone D would encompass cross country areas in both parks. It's not clear that if the zone is "full" from one concentrated area of use, does that then deny permits to those going into the same zone elsewhere? If zones are to be used (and I don't think they should) then the existing travel zones would be the best choice as more representative of cohesive ecological units.
And, as noted, I'm also hugely bothered by controlling where people can camp (with the possible exception of high use areas close to trailheads).
g.
