It's run by the smooth back side of the timing belt. If you follow the lower radiator hose up to the metal pipe on the driver's side of the engine, that pipe goes under the intake plenum all the way to the passenger side and pushes into the rear of the housing the water pump bolts to.

If you're going to replace the water pump, now's the time to install a new timing belt as long as you're there. This is not an interference engine so if you mess up the timing, no valves will be damaged.