ID type of snake

Question
PLEASE...help.  A fourth snake has decided to visit me.  I have a picture this time.  No rattle...brown with dark brown/black markings shaped like the Letter D and fading to a line.  Rounded nose, square jaw.  It was more than 3 feet long and larger than a silver dollar in diameter.  What is it?  Can it harm my pets?  I live next to a pond in south Texas (McAllen area)

Answer
Might have just been a diamondback water snake, but I will have to see the pictures. There are about a hundred different species and subspecies of snake in Texas. Most non-venomous. If it doesn't rattle, then descriptions don't help much, unless you are a herpetologist and can start telling me about divided anal plates and scale counts and such.

Post the pictures to photobucket or something and ask again, with the link to the pictures included. I'll take a look at them.