Keep in mind that not all crappie will spawn shallow, and especially if the water level is in flux. For what it's worth, I have caught spawning crappie at the 'Vine in years past as deep as 12'.
Very true! A couple of years ago we were catching them spawning in 10 ft in the slips in April. Those same slips have had 15-20 ft for most of the spring and have been too deep this year unfortunately.