Our party just did the ridge on Aug. 8th - here is the current water scoop.
There is obviously water at Ingals lake, about an hour or two before the notch. There is also obviously snow on the Stuart Glacier that can be melted just before entering the couloir to the notch (a micro light stove and fuel can be lighter than water). At the notch bivy, there is a small lump of snow on the opposite side, in the descent couloir to the Ice Cliff glacier. After that, there is no easily accessible snow on the ridge itself until a small patch or two a couple hundred feet below the summit, one pitch after taking the rap to bypass the Gendarme - if you take that variation. In the Cascadian Couloir, on decent, there is a snow field. Surface water is also available at the creek before heading up Longs Pass.
Without a stove, or time and sunlight to melt the minimal snow left on the ridge, there may be no water available between Ingals lake and the creek - in other words, nearly the whole climb.