A pond with 0.5 ac of water will require a pretty large inflow of well water to keep trout alive during the hot July August temperatures in 9 ft of water. It is much more feasable to do the well water trout in a 0.1 ac pond which can raise big trout as regularly practiced for brook, rainbow, brown and tiger trout by emeritus forum member Cecil Baird. If I was better at posting pictures here I would show you some of Cecil's current huge trout pictures all raised in 0.1 ac.
Brookie 6 lbs; Brown trout
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=180049Rainbow 9 lbs 9 oz, Brown 12 lbs
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=283273&page=1Some of Cecil's brook trout
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=426249#Post426249Suggested above was "..... or are able to keep the water temperature below 70 degrees at your deepest point". It is not just a matter of keeping the water below 70F but this water has to have dissolved oxygen above 5 parts per million (ppm, mg/L) at 70F. IN a fairly deep pond it can be relatively easy without bottom aeration to keep the bottom water below 70F; it is maintaining the 5ppm DO that is the BIG problem. The deep stratified pond water almost always wants to loose significant amounts of DO when the pond creates the upper warm and deep cold layer. The shallower the pond the more this is true.
Try trout this summer and monitor their success. When they stop feeding at the surface in just 9 ft of water they are highly stressed and close to death.
If you stock quality trout at 9"-12" as soon as the water drops to 65F in Sept or early Oct and feed them high quality pellets from the trout supplier you should be able grow them to 18 to 22" and 2.5 to 3.7 maybe 4 lbs the next June. I would aerate the water near shore during ice cover and continue to feed the trout in the open water on nice winter days. This will maintain their body weight and probably put on a little growth on them during months of ice cover.
Keep us advised as to your progress in this thread about raising your trout so others can learn from your experiences.
