Três Lagoas is a municipality in Mato Grosso do Sul, Brazil. It is the third most populous city in that state. Founded in 1915, colonization bega…Três Lagoas is a municipality in Mato Grosso do Sul, Brazil. It is the third most populous city in that state. Founded in 1915, colonization began in 1880 by Luís Correia Neves Filho, Antônio Trajano dos Santos e Protásio Garcia Leal. It is named for three lakes in the region.