Thanks zeg, that makes more sence. ESA's are a different animal all together. Here is the full decision referenced above on how they should be marked depending on what they are and where they are.
Marking Environmentally-Sensitive Areas
If an appropriate authority prohibits entry into and/or play from an area for environmental reasons, it is the Committee's responsibility to decide whether an environmentally-sensitive area should be defined as ground under repair, a water hazard or out of bounds.
However, the Committee may not define the area as a water hazard or a lateral water hazard unless it is, by Definition, a water hazard. The Committee should attempt to preserve the character of the hole.
(a) A small area of rare plants close to a putting green has been declared an environmentally-sensitive area. The Committee may define the area to be ground under repair or out of bounds, but it may not be defined as a water hazard or lateral water hazard. In view of the area's proximity to a putting green, it should not be defined as out of bounds because a stroke-and-distance penalty would be unduly harsh. It would be more appropriate to define the area as ground under repair.
(b) A large area of sand dunes along the side of a hole has been declared an environmentally-sensitive area. In contrast to (a) above, it should not be defined as ground under repair because the absence of a penalty would be unduly generous. It would be more appropriate to define the area as out of bounds.
(c) A large area of wetlands along the side of a hole has been declared an environmentally-sensitive area. As in (b) above, it could be defined as out of bounds, but it would be more appropriate to define it as a lateral water hazard.
An environmentally-sensitive area should be physically protected to deter players from entering the area (e.g., by a fence, warning signs and the like) and it should be marked in accordance with the recommendations in the Rules of Golf (i.e., by yellow, red or white stakes, depending on the status of the area). It is recommended that stakes with green tops be used to designate an environmentally-sensitive area.