Should the sentence

Without acid rain these lakes would still have fish in them.

be paraphrased like this

If there hadn't been acid rain, these lakes ...
or like that

If there wasn't/weren't acid rain, these lakes ...

Or are they both correct depending on different time reference?

I think it has a present-time reference, so I would say:

(Even) if there was no acid rain, these lakes would still have fish in them.



PaulM

Thank you. But do you think a past-time reference is completely out of question?

There was/there has been acid rain, that's why there isn't any fish in these lakes.