A.S. Yahuda , Language of the Pentateuch in its Relation to Egyptian [1933], Vol. 1, , [1933], 63 #3, Here as elsewhere the Nile is simply called mw 'water', exactly like המימ 'the water' in the Exodus narrative, e.g. 2, 10. 7, 15. 8, 16. Unlike other passages where the word is used in the general sense of water it here specifically refers to the Nile.