Beavers in the US used stolen banknotes to fill holes in their rather expensive dam in Greensburg, Louisiana.
Police, hunting for $75,000 taken in a raid on a casino, found the cash when they started breaking down the dam to drain the pond it had created.
"They hadn't torn the bills up. They were still whole," said Major Michael Martin, of the sheriff's office.
All in all, $40,000 was found in the river, and casino staff were happy to get the money back, even if it was wet.
Police think the rest of the cash is in a safety deposit box in a bank in Mississippi.
It's not known if the beavers got a reward.