It was a harmless nonvenomous Diamondback Water Snake (Nerodia rhombifer). Diamondback Water Snakes are one of many nonvenomous water snake species and are not at all related to the Western Diamondback Rattlesnake (which is venomous) or the Western Cottonmouth (the venomous snake commonly referred to as a "water moccasin.").

There isn't much you can do to deter snakes other than remove their habitat (which usually isn't practical or desirable). There are lots of urban legends about the deterrent value of mothballs, lime, sulfur, etc. but none of these products deter snakes. Neither does a product called Snake-A-Way which should really be called Dollar-A-Way because it separates people from their money rather than from snakes.

The good news is that the snake species is nonvenomous and poses no danger to pets and small children.

Well geez....I feel bad we clobbered it then! I may need to ask for forgiveness for destroying a reptile simply out of fear! Thanks for the response, and hope all that looked at my photo forgive us for our ignorance!@!!

You're welcome for the id! Its easy to make a mistake out of fear. The fact that folks are still debating what it was on the Texas Gardening forum shows how difficult identifying similar looking snake species can be for most folks.

It's just sad that people 1st intict is too kill.