I realize that the title of this topic is a LITTLE misleading...but read on!
It's fairly well documented about pike's preference for cold water. There's even been reports of guys fishing the Great Lakes for salmon and trout that have caught an occassional pike down close to 100 ft.
Springs and spring-fed creeks provide a cold water source for pike in the hot weather months...but unless you have an expensive water temp gauge (colder water sinks in the summer) finding this cooler water can be a task.
Here's a simple way to find them....in the middle of winter.
I've been watching several areas in my neck of the woods....and went out today with my camera. We've had 4 days of no temps above maybe 15* in the daytime, and night-time temps dipped down to as low as -20*
And STILL....I found open water...fed by springs or spring-fed creeks.
And you can BET the house that when the temps of summer reach +80*...there will be pike hanging out near these areas.









Now this next one is obviously a creek that doesn't have much flow or spring water....too much ice there.

Do you think I'll be fishing these areas for pike this summer???
Ya....you BETCHA! 
Life Member David BB Linkmeister
US Army '78-'85
