The Serra dos Três Irmãos State Ecological Station was created on 28 March 1990 with an area of about 99,813 hectares (246,640 acres).

A law of 30 June 2010 reduced the area to 89,847 hectares (222,020 acres), when part was incorporated in the expansion of the Mapinguari National Park.

On 13 September 2011 the area was further reduced to 87,412 hectares (216,000 acres) to make way for part of the reservoir of the Santo Antônio Dam.

Public visits are allowed for educational purposes and for scientific research, subject to approval by the responsible agency.

nigriceps), white-fronted capuchin (Cebus albifrons), Hershkovitz's titi (Callicebus dubius), white-lipped tamarin (Saguinus labiatus), black-capped squirrel monkey (Saimiri boliviensis) and the rodent green acouchi (Myoprocta pratti).

During environmental assessment studies for the upper Madeira River hydroelectric projects 27 species were seen, including 9 primates, five forms of squirrel, two of common agouti (Dasyprocta), two deer, ocelot (Leopardus pardalis), a mustelidae and three rodents.