^While babies and young children are more at risk for salmonella it isn't some big boogyman that will come and get you all.
I know media, and even doctors, try to make it out that way and say terrible things about reptiles as pets - when contamination from uncooked meats and eggs to other foods and surfaces is the most common way to get salmonella.
Bleach will kill most bacteria, molds, and viruses. Washing hands removes a lot so that it's at safer levels.
If you do decide on a pond you could build a small fence around it to keep turtles in (kids out) and adopt some. Red eared sliders tend to overrun rescuers because so many people don't want them once they're no longer a cute little turtle.
However, if you decide to make a pond it can't be a completely natural type one.
Turtles poop a lot... and always in the water, so it needs to be something that can be cleaned out and needs heavy filtering. But if you do it right it would look awesome in your yard.
If you prefer box turtles than any pond must be shallow or "box turtle proofed". They can swim if needed, but aren't the best of swimmers and tire out from it. They tend to be a bit more "hands on" if you want a turtle you can interact with.
It could be a great family pet when your child is a little older - children can learn a lot from growing up with reptiles as family pets.