There are crayfish in that reservoir, and I figured that the ginger colored jigs look like a soft-shelled crawdad. The black look a lot like a leech, and the white ones look like small minnows or fry.
We also use small tube jigs that are colored like minnows. They were called minnow squirts on one website. They have a belly on them, and really look alive.
Fishrmn