Can you go back when the water is still?
That is virtually impossible, if not completely impossible.
The location is Forrest Park in St Louis, MO. There are too many fountains etc in the area, the water is never still. Especially during daytime hours, there are always a ton of people in that park. You can actually rent paddle boats and rowboats to go around the waterways throughout the park. To put things in perspective, there are more visitors annually to Forrest Park, than Busch Stadium (home of the St Louis Cardinals) and the Gateway Arch combined.
Source: Many many hours spent in the park.
The Barbarian, when you go back, try shooting the jewel box