Kelpies are relatively rare in the US, but when I was originally searching for breeders, there are actually quite a few in the western US (and probably a whole lot more that don't have websites). They are infinitely useful on a ranch. If he's a local dog, I wouldn't be shocked to see a kelpie mix in Texas. The dilute colors of kelpie can have greenish eyes, which is what that dog's look like in the first picture.
I couldn't find a good adult picture, but here's a pup with similar coloring: