I am considering Langley for the same date (16th). Does anyone have info on water on that hike. (I have only done Whitney before, not Langley)
Lots of water in the streams and lakes of the Cottonwood Basin. Just make sure you have enough before the last push - whether it be via New Army or (Old) Army Pass - as there's no water above those lakes. By then you'll be within 2 miles of the summit if you go via (Old) Army Pass; 3 if you use New Army.