Wikipedia
Hursag (transcribed cuneiform: ḫur.saḡ(HUR.SAG)) is a Sumerian term variously translated as meaning "mountain", "hill", "foothills" or "piedmont". Thorkild Jacobsen extrapolated the translation in his later career to mean literally, "head of the valleys".
Mountains play a certain role in Mesopotamian mythology and Assyro-Babylonian religion, associated with deities such as Anu, Enlil, Enki and Ninhursag.
Some scholars also identify hursag with an undefined mountain range or strip of raised land outside the plain of Mesopotamia.
In a myth variously entitled by Samuel Noah Kramer as “The Deeds and Exploits of Ninurta” and later Ninurta Myth Lugal-e by Thorkild Jacobsen, Hursag is described as a mound of stones constructed by Ninurta after his defeat of a demon called Asag. Ninurta’s mother Ninlil visits the location after this great victory. In return for her love and loyalty, Ninurta gives Ninlil the hursag as a gift. Her name is consequentially changed from Ninlil to Ninhursag or the “mistress of the Hursag”.
The hursag is described here in a clear cultural myth as a high wall, levee, dam or floodbank, used to restrain the excess mountain waters and floods caused by the melting snow and spring rain. The hursag is constructed with Ninurta's skills in irrigation engineering and employed to improve the agriculture of the surrounding lands, farms and gardens where the water had previously been wasted.
Ninurta Myth Lugal-e describes the abundance of the Hursag: