Açu (or Assu) is a municipality (município) in the state of Rio Grande do Norte in Brazil. The population is 58,384 (2020 est.) in an area of 1303 km². The municipality contains the Açu National Forest, a sustainable use conservation unit that was originally established as a forest park in 1950. The Barragem Armando Ribeiro Gonçalves, a reservoir on the Piranhas River, is partly located in the municipality. References External links Rio Grande do Norte - Açu Homepage of Açu Municipalities in Rio Grande do Norte