This is all good information. I have a trout pond in its first year with trout in it. I have been working on the setup for two years before adding trout. My pond is fed 30 plus gallons per minute by an artisian well. What I have is small area dug 10 feet deep (less than 1/4 acre) where the well water is piped to the bottom. The well water gets exposed to the air to get well oxygenated before entering the pond. The temperature stays below 60 about 4 feet down all year. The overflow spills out into a cattail marsh and then to a 2 1/2 acre pond on the other side of 5 acres of marsh. The tout pond has some open water all year even here in Wisconsin, because of the spring. I'm not sure if the trout will stay in the small pond over winter on not. Being that the cattails only have about 2 feet of water in them, I hope they stay in the deeper water year around. So far my Brooks and Rainbows are doing well. You may consider two ponds like I did. I do think you will not be able to keep your trout alive without a spring or well due to the water getting too warm.
PS Thanks to all the members here who made my pond project a success! I would have made many mistakes without your advise.
