Hold on there, Lucky. You're mixing up numbers all over the place. Backpackers and Rangers don't leave 4 lbs per day of trash in the wilderness just because the average American sends that much trash to a landfill every day from home. Yosemite wilderness would be a huge garbage dump and we don't see that.
You're also not including the backcountry solar composting toilets in Yosemite that handle a lot of the human waste. Ironically, the composted human waste is hauled out by horses and mules. You're also neglecting the difference between humans following rules for depositing their waste away from water while horses have no concept of this. Clearly, its not a simple matter to compare human impacts to horses in the wilderness.
There should be no doubt that impacts from one horse are much greater than from one human. People don't crap all over the trail, eat tons of grass, and roll around in fragile meadows. Cumulative impacts are more difficult to compare because there are many more humans than horses, but these simple assumptions you are tossing around are misleading. This is exactly why we need more study of this problem, as described in the lawsuit and ruling.
I don't see anyone trying to ban horses in the wilderness, except maybe the fringe groups. The lawsuit is specific to commercial outfitters focusing on quantifying impacts and establishing new rules with justifiable limits. So there's no need to mix helicopters or trail maintenance into this discussion. Nobody is going after trail maintenance and Ranger support using horses.
George brings up several simple best management practices (BMPs) that should not be a large burden for commercial outfitters. I vote for George to be King of the mountain on this one. I like the idea of stockpiling feed in bear boxes and keeping horses out of the meadows to the greatest extent possible. Seems like they should be doing these things already, but unfortunately it often takes a lot of pressure to get people (especially competitive businesses) to do the right thing if it takes extra time or money. Rules even the playing field. It took lawsuits just to get them to study the problem.
I wonder how practical it is for horses to use diapers or to scoop up their droppings and carry their waste out just like humans are forced to carry wag bags on Whitney. Who wouldn't love to see less horse crap on the trails? but it's probably not very practical.
Personally, I like seeing horses in the backcountry and I'm confident commercial outfitters can make significant changes to reduce the impact with a reasonable amount of effort.
