Looks more like it was built so those sections had gates that could be opened in the event of flooding. You don't build across an arroyo in the SW without having an outlet for when the monsoonal rains hit. Too frequent to discount.
Who owned the horse?
The filly Bold and Bossy, who had shipped into Ellis Park from owner-trainer Michael Ann Ewing's Lexington base, got loose in the post parade and unseated jockey Miguel Mena.
Lexington?