not really, although we did have that drought in mid-summer and I didn't water the trees as they are so huge I figured they'd get their water from the water table. Could this be seasonal needle loss? I've been reading up online.
None of the "yellowing" appears to be affecting this year's or recent growth/needles. I would say that it is seasonal needle loss.
More images would certainly help make an ID of this issue. Show the whole tree, and its growing context. Then, show more images of the afftected portions of the tree (clearer) and association of these needles with the unaffected parts.
Never assume trees have roots into the water table, unless you are a hydrogeologist AND and a horticulturist. Most conifers have very shallow root systems, and extended drought periods can wreak havoc on them for years due to this kind of stress.