Anvil Camp via Shepherd Pass Trail

This is a 2010 backtrip trip I did from Symmes Creek to Anvil Camp via the Shepherd Pass trail. We had intended to climb Mount Williamson via the west face, but got shut down by altitude sickness overnight.

This, in my experience, is often how AMS strikes. Hikers are usually more or less okay on the first day, until they stop and camp for the night. My suspicion is that while we're away, we are able to consciously breathe faster and deeper to compensate for higher altitude.

But when we go to bed and fall asleep, our respiration rate drops to what our bodies mistakenly believe is normal (our home elevation), thus putting us into a hypoxic state overnight. Viola, you wake up nauseous and with a pounding headache.

Yes, this affects me too. In fact, it happens regularly on the first few days when I go from home to the Mammoth Mountain Inn, at 9K'. Over time I've tried to train myself to breathe faster and more deeply even when I'm sleeping—or alternately, to regularly wake up and take deep breaths to try to reset my respiration to a higher rate.

I've had mixed success.

The best way to acclimatize is to spend a few nights (at least) before a major hiking trip sleeping at a higher elevation. Ideally, spend a week in Mammoth doing day hikes and eating well and sleeping, and then go directly to Whitney or Williamson or wherever your preferred objective is.

Of course, virtually none of us have the ability to do that. Instead, if you're like most Californians, you probably drive up from your sea-level city and start hiking up on the very same day—priming yourself for a bout of AMS.

As for the trail, Shepherd Pass is a magnificent part of the Sierra but boy do you have to work for it. The trailhead is somewhere around 6200' and as it crosses from the Symmes Creek to Shepherd Creek drainages, the trail includes a mandatory 600 vertical foot downclimb, adding a most unwanted 1200' to your hike both coming and going.

— April 4, 2020

Andy Lewicky is the author and creator of SierraDescents

George Karpouzis April 11, 2020 at 7:15 am

Andy what are your thoughts on this crazy low that just dumped feet upon feet of beautiful white gold on our local mountains!

Andy April 11, 2020 at 7:33 am

These are crazy times!