Stop engine message, low coolant. After allowing car to cool off refilled reservoir. Started engine drove a mile and the water poured out of bottom. Is this a bad water pump issue?

 

probably not a water pump problem - those tend to drip not pour. What you need to do is look to see where the water is coming from as best you can - areas to check are 1) the overflow reservoir itself 2) upper radiator hoses including the feeder to the overflow reservoir and the thermostat housing 3) lower radiator hoses 4) heater hoses 5) radiator side seams

To check for the water pump, you would see water coming out of the bottom of the timing belt cover - which could get whipped around by the pulley/drive belt. for the other areas, I'd start up top then work downward. You may need to remove the valences to get a good view.

 

MT6127 you were right.
It wasn't the water pump. Radiator side seams split. Shop replaced it with a new Lassen radiator, theremostate, ECT sensor, and expansion tank if that is a real part.
I could have saved about $200 if I shopped around.
Thanks for your time.

 

sounds like the shop did right by you. Its always good to replace the thermostat and ECT sensor when doing a radiator. Expansion tanks do fail from time to time so a good time to do as well. Also its not a bad idea to replace the expansion tank cap - that's a pressure cap and for $15, its worth making new as well.