What Kin Of Tortoise Do I Have?

Question
It's a baby, only about 3 inches long. Here are some pictures. It obviously came from Las Vegas, Nevada because that is where I found it. I want to know how to properly care for it, but I can't if I don't know what kind of tortoise it is.
http://i255.photobucket.com/albums/hh152/ally_peace/tortoise.jpg
http://i255.photobucket.com/albums/hh152/ally_peace/IMAG0895.jpg

Answer
Hi Allyson,

It's not a tortoise, or a baby, and it's not a Nevada native.  I'm not really an aquatics expert, but I believe what you have is a common musk turtle, also known as a stinkpot (Sternotherus odoratus).  They are quite small turtles, and the one you have is much too big to be a baby, although it could still be immature because adults lose the keel on the carapace.  

Here's specific information on caring for a musk turtle:  
http://www.austinsturtlepage.com/Care/caresheet-stinkpot.htm
http://chelonia.org/Articles/sternotheruscare.htm

And here's more general information about housing, filtration, etc.  Note that plenty of room and excellent filtration is very, very important.  The minimum housing requirements are just that, minimums, and providing more space is always better.  For this species, a 50 gallon tank would be ideal and give a good amount of room.

http://www.austinsturtlepage.com/Care/care.htm
http://www.austinsturtlepage.com/Care/waterquality.htm
http://www.austinsturtlepage.com/Articles/filtration.htm
http://www.austinsturtlepage.com/Care/housing.htm