Did you ever use a river or a stream as a refrigerator?

Yes several times when camping or staying at a cabin in the woods. Works great when the water is cold enough.

As Deaves said : Many times when I was in the woods ! Nothing better to keep your beer cold than an ice cold stream ! 

Many times

Yes that's where I keep my ice cubes.

Nah, but I saw it done on an episode of Futurama where Fry got kidnapped by aliens and took his nose.

Yes

Yeppers.

Yes, when camping by one. I've also seen an effective cool-box made simply using a wet towel and plastic storage-drum, kept in the shade of trees. 

Yes, when out camping. Sealed the food in plastic container and then weighted it under with a rock.

yup  , and ironically  , snow as a heat  insulator . and ice to start a fire .  This post was edited by Benedict Arnold at December 2, 2016 1:23 AM MST

I haven't, but a long time ago, people would put dead bodies in the river to preserve them until they could get a coffin made and the grave dug.

It would have to be a pretty cold river, then, though it would have slowed things a bit. Dead organisms decompose even at 4ºC (typical ocean-floor temperature), although much more slowly than in warmer conditions.