The factory polymeric seals on the water pump gaskets (a combination metal/polymer gasket) are known to degrade over time and begin leaking - I don't know if it's a drip, drip, drip, type of leak, or a real gusher. I caught mine just as they were beginning to leak. Water pump was fine, but the gaskets were bad. Changing the water pump itself was not bad at all. The worst part of the process was getting the fan clutch nut loose! As an aside, I replaced the water pumps on my '99 Silverado, '04 TrailBlazer & '99 Buick Century with NAPA water pumps (manufactured by Gates) and have not had any problems with them.

However, I have experienced a couple of water pump leaks that were real gushers. Both were mid 1970s Buicks, and they leaked out as fast as the water went in!

Good luck!