Hi, What time of day was this picture taken? I am surprised you were able to work with only ISO 200 and 1/320 - It could not be sunrise time but judging from the small amount of people, it seems a bit early as well.

By the way, great shot. Hopefully I will have similar success of getting the reflection pool shot when I go next year. I will be using a soon to purchase D850 with a AF-S NIKKOR
16-35mm f/4G ED VR and would be there at sunrise to avoid any people in the shot.