Place it as close to the water as possible and a foot off the ground. If Herons are the main puprose don't put anything on it to make it more visible. Even if they do choose to land in the water they will try to walk out of it. This will work great for geese as well since they need to walk in and out of the water regularly. Either use wood posts or be very sure to insulate the posts well. You could place it a little higher if you want to let ducks pass under it.