In the first 50 years after the founding of the Mexica dynasty, the Mexica were a tributary of Azcapotzalco, which had become a major regional power under the ruler Tezozomoc. The Mexica supplied the Tepaneca with warriors for their successful conquest campaigns in the region and received part of the tribute from the conquered city states. In this way, the prestige and economy of Tenochtitlan gradually grew.  In 1396, at Acamapichtli's death, his son Huitzilihhuitl (Nahuatl: "Hummingbird feather") became ruler; married to Tezozomoc's daughter, the relation with Azcapotzalco remained close. Chimalpopoca (Nahuatl: "She smokes like a shield"), son of Huitzilihhuitl, became ruler of Tenochtitlan in 1417. In 1418, Azcapotzalco initiated a war against the Acolhua of Texcoco and killed their ruler Ixtlilxochitl. Even though Ixtlilxochitl was married to Chimalpopoca's daughter, the Mexica ruler continued to support Tezozomoc. Tezozomoc died in 1426, and his sons began a struggle for rulership of Azcapotzalco. During this struggle for power, Chimalpopoca died, probably killed by Tezozomoc's son Maxtla who saw him as a competitor.  Itzcoatl, brother of Huitzilihhuitl and uncle of Chimalpopoca, was elected the next Mexica tlatoani. The Mexica were now in open war with Azcapotzalco and Itzcoatl petitioned for an alliance with Nezahualcoyotl, son of the slain Texcocan ruler Ixtlilxochitl against Maxtla. Itzcoatl also allied with Maxtla's brother Totoquihuaztli ruler of the Tepanec city of Tlacopan. The Triple Alliance of Tenochtitlan, Texcoco and Tlacopan besieged Azcapotzalco, and in 1428 they destroyed the city and sacrificed Maxtla. Through this victory Tenochtitlan became the dominant city state in the Valley of Mexico, and the alliance between the three cities provided the basis on which the Aztec Empire was built.  Itzcoatl proceeded by securing a power basis for Tenochtitlan, by conquering the city-states on the southern lake - including Colhuacan, Xochimilco, Cuitlahuac and Mizquic. These states had an economy based on highly productive chinampa agriculture, cultivating floating gardens in the shallow lake Xochimilco. Itzcoatl then undertook further conquests in the valley of Morelos, subjecting the city state of Cuauhnahuac (today Cuernavaca).

Answer this question "who conqured the lakes" by extracting the answer from the text above.
Itzcoatl