Comment from Joe Offer: I always cringe when I see this "Waters of Babylon" round attributed to Don McLean, or to some other modern artist. I checked a number of sources. Some attribute this setting of Psalm 137 to William Billings (1746-1800) of Massachusetts. Others say it is "erroneously attributed" to Billings. Some sources call it a "traditional Jewish melody." Daniel Harper of Northern California researched the song, and found a copy of the melody in a 1786 book titled The Muses Delight: Catches, Glees, Canzonets and Canons by Philip Hayes, page 105.
Makes it a bit older than old Don McLean, doesn't it?