In wimberley ours is.. hundreds of 'em. Spoonies and Ring Necks mostly, but have seen redheads, buffleheads, Pintails, and bluebills on it as well. I check it almost every day and they are ALWAYS there!
Years ago (back when lead was legal) we used to hunt the gravel pits in Ft Worth behind Bell Helicopter. Had some amazing hunts and then someone told us about there being tons of birds on the waste water lagoons which were located about a half a mile away from where we were hunting and in the same directions most of the birds we shot were coming from. Duck hunting the gravel pits kinda lost its flavor after that.
I sell water/wastewater equiptment and trust me, there are more birds that stop at wastewater treatment plants then you think. Every plant I sell to in NTX will have birds loaded up on their lagoons and or clarifiers. It's worse when everything is frozen up and the birds can spot those plants from miles!