Burrowing nymph

I often see these little trails on the creek banks and marvel that something is crawling around in that sand and silt, and making a living at it. One time, I had to dig one out, to see what kind of critter was responsible. I assumed it was a bug and, sure enough, it was an ugly, creepy- looking larva. I guessed it was a dragonfly nymph of some sort.