One thing for sure is that fish don't follow rules, they just adjust to their environment. Crappie are found in drastically varied water bodies, but where they hold is always in relationship to factors like water clarity, water temperature, forage, and structure. I'd say that your fish in the canal and Marian are putting themselves near the level of their food. Baitfish schools are usually in the mid to upper level of the water column, so those specks are primarily located according to their stomachs and if there is a piling, steep bank, or something nearby they will pull up against it. On the other hand, Washington and the Farm are quite shallow so the fish can easily hold close to the bottom while the food is still just a few feet above them. Thats my take.