jawbone - Saw your pond pictures. Since you have a stream running into your pond, it would probably be pretty useless to kill it off. Some trash fish would get back in via the stream.
My guess and experience is that as fast as the pond is refilling all the fish in the low pool will survive. You won't lose many over winter unless you have a very severe winter with lots of extended snow cover (10-14 weeks). Restock in the spring and manage for what you want to achieve. A strong bass population will do a prety good job of keeping the trash fish in control.
