Between a stack of pallets and a green waste bin in a parking spot under the brick building with a large bell on it at the Cluckin' Bell Farms factory in Paleto Bay.
One can also be found on top of a sunken freighter off the southeast coast of the land mass.
A third one can be found in the Davis Quartz mine, near the middle of the mine. Looking at the map, the very bottom road in the will curve upwards towards the middle of the mine, and at the very top there's a very short road going straight north. On this outcropping there are two small houses and two porta potties. The crowbar is lying on the ground in front of the porta potties.