The posted Cordinates are for parking.
If you want to find this Mystery Cache then you need to complete the nearby Adventure Lab. When you play the game clue and solve the case you will be awarded with the cords to ground zero.
once you have the crods and go to parking you have two choices of approach. stay on the left of the creek and bush wack in to the Geocache Or cross the creek using the bridge and once you get close to ground zero cross the creek again this time without a bridge. but way less bushwacking.