minnows

I live in Montana and not alot of fishing to speak of here. I am closer to the Black Hills than I am to alot of places in Montana. I also do most of my shopping in Rapid City and Spearfish. I am gonna start doing all of my fishing in South Dakota. Don't get me wrong I love to hunt so I am staying in Montana!!
Anyway where can I get minnows at in the Black Hills area including Belle Fourche, Spearfish, Custer and Rapid? I want to know the places that are pretty much guaranteed to have live minnows. I have driven to Shadehill and Bowman Haley Dam in North Dakota on several Saturdays only to find they do not stock many and they are sold out.

Also wondering if New Wall Dam is a good fishing spot and if it is easily fished from shore or if the weeds and mass gets pretty bad there? I would like to take my kids there on the 4th of July. I grew up in South Dakota and dad used to have a cousin that ranched just west of where New Wall Dam is and we did alot of deer and antelope hunting in the area but never checked into the fishing.

I am interested in some Large Mouth bass dams too?