What type of Garter is this?

[mb90078]

Hey everyone, thanks for the quick replies!

I apologize about the low quality of the pictures, but to be honest, they turned out better than I had even hoped they would (cell phone camera). I only have one more picture that I took of it with me, which is pretty similar to the 2nd one I showed you (which is why I didn't include it at first), but maybe the slightly different angle may be of help?

Found it in Eastern Iowa, so I guess most of your guesses of Radix or Sirtalis seem plausible based on region.

Just found it interesting cuz it was the first "wild" snake I've seen/caught (very temporarily) after living in the Chicago suburbs most of my life and then three years here in Iowa. Ironically, just last week I saw my first lizard (with the exception of vacations to Florida), a skink just a half a block from where I found this guy. Crazy what you can find when you keep your eyes open.