Then Wakinyan wrapped robes of great clouds about himself and flew over the waters. He dipped the robes in the waters until they were soaked.

Unk saw the robbery and came with Ibom to resist it. Ibom and Wakinyan fought fiercely. Their struggles tore the clouds and tossed the waters in great waves. Ibom roared and smote. Wakinyan bellowed and thundered and glanced flashes of lightning from his eye. Ibom, overcome, fell, and Unk drew him beneath the waters.

Then Wakinyan flew over the grounds and squeezed his robes so that they spilled the waters on all the forest and the prairie, and the lands were made moist. Skan was pleased and caused the plants to draw up the water into their veins, and made it into sap for their nourishment. Thus Wakinyan invented rain and ever since has moistened lands with rain so that all plants may have water for their sap and nourishment. When the lands are wet with rain, the plants grow and flourish.

Lakota Myths, p. 231-232