It was narrated from 'Amr bin Shu`aib, from his father, from his grandfather, that :
the Messenger of Allah (ﷺ) ruled concerning the stream of Mahzur that the water should be retained until it reached the ankles, then released.
English reference: Vol. 3, Book 16, Hadith 2482
Arabic reference: Book 16, Hadith 2576