Our course has a couple of greens with large stone/concrete blocks acting as a retaining wall. At the base of the wall is a water hazard. Presumably, if the course were marked, the retaining wall would be inside the hazard. If you were marking the course, would you place the hazard line exactly on the edge of the retaining wall or some inches past the edge?
If the hazard line is on the edge, players will get relief from the wall's edge. Drawing the line somewhat away from the wall's edge leaves some balls inside the hazard and essentially unplayable without taking relief from the hazard. Or does one just declare the retaining walls an integral part of the course?