Clay's right-- it's tech term is thermocline inversion--- colder surface water sinks and the whole lake flips. Stirs it up, which is great for re-oxygenating the bottom water. Import for the lake's lifestyle, but tends to suck for the fishing since it's a huge change. And you know how even little things can affect the fish bite. The hooch turns green/brown when it happens because the lake bottom gets stirred up, and it's bottom water coming out of the dam (which is why it's so cold even in july).
marleymoo: wading works, but a canoe or kayak is better-- you can get to more of the deeper holes. However, any of the accessible shoals near 285 are both wadable and have holes. What i've found is that the tails of the deeper runs at shoals tend to hold the fish (really, just like any predator-- they'll be hanging just outside of the current looking for bait struggling in the fast water). Throw a white or natural fluke upstream of the deeper runs, so it has time to sink by the time it gets to the tailing edge of the run, where the big boys sit. Just like trout--- or just like what the trout used to do in these runs until the stripes swallowed them whole! By the way-- I've seen schools of both shad and herring in the river now and again.
Light tackle is asking for trouble-- these are fish ranging from 3-20 lbs, and the mid- to large sized will either strip your reel or break your line once they get into the current. I've seen heavy jig hooks get straightened. Picture pulling an angry, fully open lead umbrella against a stiff current. A med-hvy wgt rod with braided line may seem like too much, but I can tell you it can be very handy. However, I have seen 3-5 lbs landed with fly rods, but thru luck and patience. Nothing over 5 lbs is coming in on a fly rod without a boat to chase it
Low light is always best on the river--- there's no dark depths for them to hang out in like on the lake, and stripers tend to avoid sun. My largest was just at dusk-- in fact it was fully dark when i finally landed it. My assumption is dawn and before is also good--- haven't gotten up early enough often enough to know this firsthand
Not trying to sound like an expert-- just telling you a summary of what i've learned by experience and from others i've talked to, particularly a friend who lives on the river and works it several times each week.