I always fish the back flow of the currents while fishing the Guadalupe. As for stock ponds I have never caught a trout on them much less do I know of any stock ponds in Texas that hold trout year around.
Side note: As mentioned by Chuck "Banker" look for the fish feeding. Look for the swirls on top of the water. The only pond I have fished for trout was at Live Oak Lake two years ago. There are no signs to look for them. Pond is super small. Just cast a bait or lure and you usually got a fish. These were all stock trout.