wait for the big sioux to freeze in the winter time, other than that not much around here.
you could try the Sioux Valley Cycle club, but its basically a pasture and a some MX and TT tracks and requires a membership.
Other wise there is Talsmas atv park and then the other OHV place out in pierre thats all I can think of east river SD.
then you could also throw in the Appleton OHV park in western minnesota.
