plants will oxygenate while alive but when decomposing will rob O2. id get a backhoe in there and dig as deep as they can. a small deep pond is better than a large shallow one esp. in your climate. plant a lot of fast growing water loving shade trees around it will help keep water temps down. around here people look for natural springs to build their ponds near which will give some cool water in the heat of the summer. you don't need much water flow to make a big difference. good luck!
Steve Thorn wrote:I'm thinking that the minimum depth needed could also vary depending on a few factors.
Shade- Maybe having lots of shade during our hot summers will help cool the water and regulate the temperature during this hotter part of the year. Our winters rarely get below freezing for long.
Lots of water plants- to create highly oxygenated water and additional shade to cool the water and create cover for the fish to hide.
Size of the fish- I'm guessing that really small fish could thrive in really small amounts of water here. I bet most of the sources talking about minimum water depth are referring to raising large sport fish. There are some wild fish here that don't get more than a few inches long at most. These types of fish might be a good fit for small pools.