When you are conducting a competition, having a properly marked golf course is crucial in minimizing Rules issues. Determining whether a water hazard should be marked as a Water Hazard (yellow lines or stakes) or a Lateral Water Hazard (red lines or stakes) is an important consideration.
A Water Hazard is marked with yellow lines and/or stakes, and it should be the default marking. When you have a water hazard where a player is unable to proceed under Rule 26-1b, which requires dropping behind the hazard while keeping the point where the ball last crossed the margin of the hazard between the hole and where the ball is dropped, or the Committee feels it is impracticable to do so, the hazard meets the definition of a Lateral Water Hazard, and you should mark it with red stakes and/or lines.
Frequently you will have a water hazard where, at some point, it becomes impossible to proceed under Rule 26-1b. In that case, you will need to transition from a Water Hazard to a Lateral Water Hazard.
When you have a transition such as this, you should always place two stakes, one yellow and one red, at the point of the transition. In selecting the transition point, make sure that a player whose ball crossed the margin where the line is yellow will have a place to drop under Rule 26-1b, no matter where the hole might be located on the putting green. The transition point should be readily visible to players from the hitting area, when possible, in order to remove any doubt as to where their golf balls last crossed the margin of the hazard.
John Van der Borght is the manager, Rules of Golf, for the USGA. Email him at firstname.lastname@example.org.