Yep, in addition to water we have dirt roads, horse-drawn buggies, and some places even have electricity in homes!!!
All kidding aside...
If you're looking for prairie dogs you're going to need to head west, at least the middle of the state or farther I'm guessing. I'm not sure, but I know there are none close to the East side of the state, that I am aware of.
A lot of good lakes all over in SD, some good ones in the SE part of the state, and a lot of fine fisheries in the NE part of the state as well. The Black Hills is an excellent vacation area with many attractions and tourist arenas.
I'd start looking through
http://www.travelsd.com/. The Things to Do has a Fishing and Hunting site that should key you in on some sportsman stuff.
Enjoy your trip!