Enanatum I was the brother of Eanatum and another son of Akurgal. He had a wife named Ashumen and at least three sons named Meanesi, Lummatur, and Enmetena, the last one of which succeeded to the throne. Enanatum undertook a number of renovation projects including the rebuilding of the Dugru shrine of Ningirsu, the Ibgal of Inana, the temple of the goddess Amageshtinana, and the egal of Hendursag (Bauer p. 467).
Like his predecessors he faced conflict with Umma over control of the Guedena. In a tablet dedicated to the god Hendursag excavated at Lagash (FAOS 05/1, En. 1 29), Enanatum describes how Ur-Lumma, the ensi of Umma made an incursion into Lagash's territory, seizing the Antasura and reaching as far as the 'Blackdog Hill' (DU6.UR.GE6). Under instruction from Ningirsu, Enanatum defeated Ur-Lumma's forces at the boundary canal and nearly caught the king himself. These events are also treated in a slightly different manner in the Enmetena cone (Ent. 28, II 27-III 10). There it states that because Ur-Lumma was unable (or unwilling) to pay the tax on grain lent to Umma by Lagash, he hired foreign mercenaries and invaded the far side of the Guedena, destroying the shrines and stela erected by Eanatum and diverting the boundary canal of Ningirsu. Finally Enanatum defeated him at the Ugiga field of Ningirsu.