Unktehi, a water monster, fought the people and caused a great flood. The people retreated to a hill, but the water swept over them, killing them all. The blood jelled and turned to pipestone. Unktehi was also turned to stone; her bones are in the Badlands now. A giant eagle, Wanblee Galeshka, swept down, saved one girl from the flood, and made her his wife. [Erdoes & Ortiz]
In another version, the thunderbirds fought and defeated Unktehi and her children before the waters washed over the highest mountain. [Erdoes & Ortiz]
or
References: Erdoes, Richard and Alfonso Ortiz. American Indian Myths and Legends, Pantheon Books, New York. 1984.