Good morning TyW33. Critterhunter gave you some good advice, and I think I can add a little more.
I'm about 3 hours west of Mankato on Highway 14, so we should have some similarities.
I'm going to discourage you just a little on walleyes. Primarily, I very much doubt that you'll get reproduction in a 10-acre pond. Even if you get a little, it's almost certain that it will not be enough to maintain the population. If you want walleyes, and EVERYONE is walleye crazy up here, then you'll have to stock.
We're managing a couple of 20-acre ponds near Brookings that are walleye-yellow perch combinations. We have to maintain the walleyes by stocking (the perch take care of themselves). If I see even one or two age-0 walleyes (naturally produced) in the fall electrofishing survey, that is about the peak. Most years, we see no survival of naturally reproduced walleyes.
When we did the first pond, I was scared to death that the yellow perch would overpopulate and stunt. So, we stocked too many walleyes too often, and their growth was very slow. However, we produced 12-13 inch yellow perch as a result!
On the second pond, we're stocking fewer fish, and letting a commercial fish dealer from the area harvest some of the smaller walleyes. We've been able to get faster growth as a result, and the perch are still under control (9-10 inches long after 3 years).
You do have a couple of other management options for your pond. Yes, you can use the tried and true largemouth bass-bluegill combination. It works just fine up here. You'll be able to produce 8 and 9 inch bluegills for the table, if you so desire. Also, the largemouth bass-yellow perch combination works very well up here.
The other option you might consider is smallmouth bass. If you want a FUN pond fish, you can't beat them. Man, they are fighters and jumpers. We use smallmouths in quite a few of our ponds. The primary problem is that they are not as effective a predator as largemouth bass, and I would STRONGLY discourage putting a panfish (say bluegill or yellow perch) into the pond. The panfish will overpopulate and stunt, in nearly all cases. Also, the smallies themselves tend to overpopulate and stunt. So, after a few years, you will need to harvest a lot of small bass (say those under 12 inches) each year, to keep up growth rates and make sure there are plenty of 15-18 inch smallmouths for catch and release.
I am a little worried about your pond depth. Maybe MN is "better" than SD, but 12 ft depth is pretty marginal around here. You mentioned a sand layer -- does that mean that you are down in the ground water table? If so, you may be OK on depth. Our gravel pits around here make it through the winter with as little as 8-10 ft of water. A "hill pond" (a dam pushed up on a draw, holding water behind it, and relying on runoff to fill it) should be a lot deeper in eastern SD. Even 20 ft is not too much, as that will be lower in drought years.
Well, that should give you a little food for thought. Let me know if it brings up any other questions.
Dave
