I just went up yesterday.
I only got up to UBSL before we needed to cut our trip short (buddy got injured), from what I remember from the MR, there are no water crossings above that.
As it was, there are 7 crossings to speak of:
1: Carillon Creek on the Whitney Trail before the MR.
2-3: The two before the ledges on the N. Fork of Lone Pine Creek (NFLPC).
4: There is a small creek that feeds into NFLPC above the ledges but below Lower Boy Scout Lake (LBSL).
5: There is the outlet of LBSL
6: The slab creek crossing below Clyde "Meadow"
7: The outlet of UBSL
For most people with trail runners or light boots you should be able to manage crossings 1, 4, & 7 without needing water shoes or a barefoot crossing.
Crossings 2&3 below the E-Ledges will most likely require water shoes.
Crossing 4 you can remain dry but it flows along the trail for a bit.
The big daddy is crossing 5. Unless you know/willing to try the Slab Route you will need to get your feet wet crossing the LBSL outlet.
To put LBSL in perspective: I wear Saloman 4D's which are waterproof (effectually) high tops. I was able to do the two crossings up to the ledges with my shoes on and my feet were dry (it took some acrobatics) and I kept my shoes on for both trips when I crossed them at 3AM and returned at 1PM.
Even with waterproof boots the water at the LBSL outlet the water was mid thigh for me and crotch deep for my shorter buddy
Crossing 6 is a series of shallow crossings. There is one deep brook that I managed to cross dry, but if you're wearing light boots or trail runners you might want to play it safe and remove the shoes. Follow the cairns in this section up through the slabs.
7 is pretty minor, there are some easy spots to cross closer to the lake if the crossing along the use trail is too rich for your blood.
I don't believe that the MR has any crossings above that.
Also, up to UBSL we didn't set foot on a patch of snow.
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