I agree with AROTC's list but I'd replace the flashlight with a chemlight (Cyalume) which are fairly cheap. I would always take a flashlight on a day-hike in case it goes wrong.

My Camelback Mule has a quart bottle of water (bladder was removed), compass, 3 trashbags, 20' paracord, 3 green cyalume chemlights, UK 4AA eLED flashlight, SAK Trekker, small FAK, ferrocerrium rod, Bic lighter and a film cannister w/ tinder. It's lightweight and not at all restrictive.
_________________________
Better is the Enemy of Good Enough.
Okay, what’s your point??