'Fresh' in the Bible

Then he said to me, “These waters go out toward the eastern region and go down into the Arabah; then they go toward the sea, being made to flow into the sea, and the waters of the sea become fresh.

It will come about that every living creature which swarms in every place where the river goes, will live. And there will be very many fish, for these waters go there and the others become fresh; so everything will live where the river goes.

But its swamps and marshes will not become fresh; they will be left for salt.