Actually, there are some areas for trout fishing here in Oklahoma. Some areas, such as SE Oklahoma, are natural. But there is a reason it doesn't work. It's called 'Thermal Kill'. It's basically what happens when the water is simply too warm for the fish to live, and they die off.
There is a small lake in Oklahoma City that plants rainbows every November I believe. These trout survive until about June of the following year. A consistent warm temperature slowly kills these fish. So, plant all ya want! THEY'LL DIE. I don't agree with planting them to live or be caught for a season, but it is what they do.