They are an elusive breed of fish - aren't they !! General consensus would have the White Crappie being in the shallow water ... and the Black Crappie being in the deeper, cooler water. I don't find that to be a 100% accurate assumption...and that makes finding them a tad bit more difficult. It would be so much more simple, if the Crappies would play the game fair !! :p
At this time of year - and with water temps being in the 80's ... I'd expect the White Crappie to be close to the schools of baitfish - wherever they may roam. That could be up in the flooded terrain (with rising water) or out in the middle of the lake (with falling water). But with water temps that warm - you can bet they are actively feeding on a regular basis.
White Crappie are notorius for being quite deep during Summer ... and just as notorius for being in relatively shallow water during the wee hours of the morning (and not necessarily around the bank!). Being a predator of mostly other fish (baitfish species) - White Crappie are usually not far from baitfish schools - even if they have to suspend in open water. But they will still usually relate to some form of structure - humps, brush piles, creek channel bends/edges, river channels, bridge pilons & docks in deep water, etc.
Another consideration - thermocline depth ... if your lake stratifies during the Summer - find the thermocline level ... it could be 15ft deep, 30ft deep or even deeper (depending on the average depth of the lake, and water clarity, and rate of displacement - for those lakes with power generation dams). Once you find the thermocline level ... then find structures that extend from below that depth, up thru it, and still don't break the surface (less likely to be a "community" hotspot). Any such spot that is close to a cliff, or area of water that doesn't receive sunlight "all day", is potentially better. Fish these spots from mid-thermocline depth to about 3ft above the thermocline top. Fish with live minnows, &/or Shad/baitfish species, and fish them slow (deadline) and use as many poles as you can handle (and is legal). The use of "added" garnishes can also help - like: Crappie Nibbles, Mega-strike, Berkley Power tubes/live bait, pieces of live worm or larvae along with the "minnow", etc.
I'd also expect them to be holding tight to the cover (even in deep water) during the main portion of the day ... and only suspend above or away from the cover during the early and late hours of the day.
They might have gone into the flooded terrain as the water was rising (at least those that were already shallow) ... but, suspect that with the falling water levels, those fish have retreated back away from the banks.
I'm not so surprised at the "elusive" nature of the White Crappie, as I am of the relative shallowness of the Black Crappie !!
I was always under the assumption that Black Crappie liked clear water, cool water, deeper water, and weeds ... but after my last trip to my home Crappie waters - that assumption didn't hold up. My water temps are in the 80's too, and I caught Black Crappie less than 10ft deep
!! And that was on a "blue bird sky" day, from 8AM-12AM ... trolling a crankbait trailing a jig - for White Bass. And they came off a hump with brush/standing timber, out in the middle of the lake ... even with heavy boat traffic ! The water around the hump ranges from 20-35ft - the hump comes up to between 11-14ft deep, and the timber comes up to within 4-6ft of the surface. Had I been targeting White Crappie (or Crappie in general) I would have been fishing about 20-25ft deep over 30-50ft of water - in standing hardwood timber ... and using live bait (or possibly "vertical casting" with small marabou jigs or jig/minnow combos). That's the "normal" daytime pattern, this time of year, at my home lake. Finding that "one" tree or area that they're schooled up on is the hardest part - after that, just getting the bait in front of them is usually all it takes to get bit. .............luck2ya ........cp