I've been keeping a pretty extensive one since 1995, just on Steelhead. They are a great reference. The most important thing I find that doesn't stick in my memory very well is water levels. I can go back and find which holes fished best at certain water levels and be sure and fish those when the water is right. There's a hole on the Green that's only wadeable when it's down to a certain level........check the water level on the computer and cross reference it with the fishing log and I know when to hit it............