The web trace theorem of Douglas, Kenyon, Shi expands the twisted Kasteleyn determinant in terms of traces of webs. We generalize this theorem to higher genus surfaces and expand the twisted Kasteleyn matrices corresponding to spin structures on the surface, analogously to the rank-1 case of Cimasoni, Reshetikhin. In the process of the proof, we give an alternate geometric derivation of the planar web trace theorem, relying on the spin geometry of embedded loops and a `racetrack construction' used to immerse loops in the blowup graph on the surface.