Bill,
Ed is correct. When the water temperature hits 90 degrees, the big fish  head 
for deeper water. It doesn't take much actually. The warm water sits on the  
top. Go down ten or fifteen feet and you will notice a huge difference in 
water  temps. Scuba divers are few in this lake because they say the water isn't 
clear  enough, but anyone diving down more than twenty feet or so will always 
be in a  wet suit.
 
Rummy