what kind of turtle did i find?

Question
We live in north eastern wisconsin and we found a baby turtle in our back yard.  This is the first time since we've lived there (5 years) that we have ever seen a turtle.  We do have a stream that runs through the property so it wouldn't be unlikely.  It's really tiny and it's hard to figure out what it is.  We didn't want it to get eaten so we put it in a fish tank with half rock and half water. It seems to prefer the water.  We tried feeding it lettuce and carrot pieces but it didn't want them.  We then bought some generic turtle food that look like floating green sticks and he ate those right up. Upon looking at pictures in books and on the internet he looks like he's either a snapping turtle or a wood turtle.  He has claws, a bumpy carapace, and is dark green with some yellow and green pattern on the rim of his shell. Please help me figure out what it is.

Answer
Hopefully it is not a wood turtle- they are rare and very protected in most places.

The most common turtle that sounds like yours is the Yellow-belly Slider. http://www.austinsturtlepage.com/world_of_turtles/Yellow-bellied_Sliders_-_Trach...

These guys make good pets if you want to make a nice habitat, but it can cost $200 easily to set up a tank correctly (20 gallon long with good filtration, UVB lighting, heat controls, etc.)

They do not eat veggies in the wild- mostly insects, worms, etc.

In general, they will have a longer life span in the wild than they will in captivity unless you work to give them a good home. A good care sheet is located at http://www.austinsturtlepage.com/Care/cs-yellowbelly.htm