Another major flood occurred when the North American icecap melted. This one was not as dramatic as the earlier one when the greater bulk of the Antarctic ice cap melted.
That one generated vast quantities of melt water in a short time, and it's possible that it was released suddenly generating a massive tsunami that penetrated all the way to the North Pacific and Atlantic oceans.
They'd remembered that one too if they were living up in the mountains ~
However, that was 16,000 or so years ago ~ before writing ~ and I think it's probably impossible to transmit oral tradition from 14,000 BC to 5,000 BC about any matters of major importance.
The Black Lake event is older than the "young earth" crowd computes so it couldn't have happened and the whole place is still totally freshwater (right ~ bwahahahahahahaha))