Actually, the "Flood" story is indeed a Sumerian one. The tale says:
As people started doing evil and paid no more attention to gods, they became very frustrated and wanted their revenge. So they sent a flood which drowned all of the humans, except a guy named "Shamash- N' Pishtim" (Note that Shamash was the Sun God of Sumer) was saved.
Also they're strong evidence that probable this flood was a rise of "Persian Gulf" which stretched up to Sumerian cities then.