We have lots of natural water in the PNW, so I've never heard of that term. I can certainly see the need for 'tanks' in drier regions, though. I think any dug watering hole up here would be referred to as a 'farm pond.'
The pronunciation of creek can be a bit fluid -- when referred to with its formal name, I use creek (we live on Church Creek), when referred generically, I call it crick (you kids go down to the crick and find some frogs).
