I think there's two kinds of lakes. Lakes where all the trout die in the summer and lakes where the trout do not die.

On lakes where all the trout die, they do most of their dying in July and August. As they die, the bass eat them. As they die, they seem to go shallow. I know that doesn't make sense, but I think that the trout get really screwed up when the water goes over 80 and they can't go deep to find cooler water.

So you get a lot of nearly dead trout in shallow water, and the big bass love an easy meals so you can catch them occasionally. This doesn't mean that fishing is good. Big bass have easy pickings in general during the hot months, so they only feed during a short window. I think that the really big ones don't eat every day either, I think they only eat occasionally, every few days.

It's not an easy condition to catch big fish on, but they can be caught. They are most likely to be caught on lakes where all the trout are dying or dead, and they are only likely to bite during small windows during the day. The trick to catching them is to throw swimbaits only, and do it all day, or all night, or all day and all night. A lot of people think your only shot is at night. That's not true. You can catch big bass during the middle of the day in the summer in 80 deg + water. It's just that most people don't try.

And that's the other upside to fishing right now - minimal pressure from other guys fishing for big bass (unless they all get excited by reading this lol). Most people don't like fishing in hot weather and they go home at 1pm. I see boats on the freeway at 2pm in the summer all the time. It's hard to get the fish if you only fish for 6 or 8 hours, you might miss the window. That's why I wear funny looking hats ;)

You asked about depth... I don't think bass go in to 200 feet of water, but they probably go down to 100 on some lakes (cough Pedro). Bass may suspend over any depth but I don't think they like to live super deep.

I've caught three 15lbers in July-Sep and they were all in less than 10 feet of water. They may not live that shallow, but when they get hungry that's where they go. Think about how many times in the summer time you see small fish up shallow - think bluegill, young of the year bass, shad, etc... Where there's life, big bass follow, they are predators. Big predators go anywhere to get the best access to food.