There was a sea next to the beach and you could see the water surface before. But now the water surface disappear and the problem occur in other maps too.
Minimum graphics is reason. It's not a bug.
Your (low) graphic settings are probably the reason, I can see the water just fine on high graphic settings:
That's either during a major drought, or it's the ocean receding just before the tsunami hits.
Which graphic settings are you running the game on?
Increase your graphics quality to high and it will appear again
Customer support service by UserEcho