Carp might be spawning in some areas of Minnesota but in the central part of the state, it's a bit too early.  Watch for the carp to move shallow when the water temperature reaches 70 degrees.  Spawning activitiy doesn't last long - only a few days.  Dark bottom bays warm first, so keep an eye on those spots.  Early morning is when carp are most active.  Spawning carp are noisy so listen for the splashing as the big fish procreate.  In most locations a boat is not needed - a pair of waders will get you to the action.