Four Mile Trail washout(s), February 2015

It looks like a lot of water, carrying rocks, came down across two adjacent sections of the Four Mile Trail sometime in February and seriously messed up the trail. A local mentioned that the Valley had received something like 4 inches of rain on February 9th, so that could have been the occasion. I was on that part of the trail in late January and happened to take the "before" pictures below (among many others, of course). It looked entirely normal then but by late February, it looked like the "after" pictures -- and still does, unless a trail crew has done something to it in the last two weeks.

The area is around the 4400-foot elevation, near the switchback that comes closest to Sentinel Creek. Here's a piece of topo map and two pieces of satellite view. I put the "crosshairs" as close as I could to the estimated location of the washouts and left them there as I changed views.







A few hundred feet before the switchback there's a little "cobblestone" (riprap, I guess) ramp. It slopes up from either side to a ridge at the top, sort of like a roof. I used to wonder about its purpose, but now I think it was put there to shed water and keep it from eroding the trail. The view from the top of the ramp, before:



And after:



Here's the view looking back at the ramp from farther up the trail, before:



And after:



A few hundred feet after the switchback there's another section of riprap with a stonework retaining wall on the uphill side. Before:



And after:







The trail is still passable, but not as easily as before. In some places you're stepping on not-very-stable loose rocks.

From looking at the topo and satellite views, I'd guess that the source of the water was the valley just below where the "Sentinel Rock" label appears on the topo, and that the water came down by way of the boulder field shown in the satellite view.



Edited 1 time(s). Last edit at 05/05/2015 07:30PM by gophersnake.

Won't they close it to fix those walls?

Quote
hotrod4x5
Won't they close it to fix those walls?

I'm not sure. Two years ago, when they were moving rocks around and building walls just below Union Point, they'd sometimes ask hikers to wait a few minutes but the trail remained open the rest of the time. Here are a couple of pictures I took while I was waiting: