A couple veteran waders made strong suggestions about staying hydrated in the comments of Friday's Chicago WWW. Before you think this is as ignorant as TV people telling you to stay cool when it is really hot, there is some very specific reasons for waders and the warnings to stay hydrated.
Years ago, long enough back that we only had two kids and I could more regularly spend as much as 8-12 hours fishing, I would sometimes come in at day's end and my head would be exploding with a headache and it would take a day or so of hard-core ibuprofen usage to knock it back.
It was bad enough that I was beginning to worry that I was working up towards a stroke at a young age.
Then I think it was Ken Gortowski, I will give him credit anyway, pointed out I was probably suffering from dehydration headaches. He had a couple basic suggestions and I added a few over the years: drink at least a quart of water before going out, take a good multiple vitamin and pop a couple ibuprofen beforehand.
I then try and force myself to very consciously drink during the day. No I don't mean beer or caffeinated drinks like coffee, tea or colas that will add to the dehydration.
On really hot days, I will keep a Gatorade around, but usually I stick with water.
The reason somebody like Norm Minas made the original suggestion about staying hydrated while wading is from his years of wading experience.
Wading (or even fishing from a boat or shore) plays tricks on your mind, or at least mine. For some reason, being by water makes it easy to forget about drinking and staying hydrated.
And when it is as hot as the weekend was, it is easy to wade into a river, especially one like the Kankakee where I am comfortable wet-wading, and not think about staying hydrated.