Why can't I place water anywhere?

[Wrathloki]

No matter how deep of a pit I dig or how much I mound up around a hole, I can't place water. The lines are always red at every level. Why can't I place water? How do I get this working? I've never had this problem with Planet Zoo so I don't know what I'm doing wrong.

 

[Wagi]

Double check that there are no paths or ride stations nearby, also make sure there's nothing hidden underground (including any 'tunnels' that might have been created when you dug your pit ). Attach a screenshot of your empty lake bed if you can...

 

[Wrathloki]

I think I figured it out. I wasn’t making the pools wide enough in area. It seems there’s a minimum square footage for adding water.