How to diagnoss water pump problems

Two very likely cuprits. The coolant will leave a white stain when it dries.
A waterpump with a leaky seal will fling coolant around making it harder to spot a trail. It will however get worse with time.
You can try putting newspaper under the car and seeing where the wet spot is.
Passenger side behind the wheel is most likely a pump.
Front either side is a rad. They tend to leak on the drivers side.

There is a pressure test that a garage can do if it has the adapter for the saturn coolant bottle.

How many miles? My pump went first at about 115,000. The rad was next at 125,000.

Good hunting and let us know. :)

You can get a good look at the pump from underneath. Be sure to use jack stands. :