The Piagaçu-Purus Sustainable Development Reserve (RDS) is divided between the municipalities of Tapauá (30.35%), Coari (1.37%), Anori (40.11%) and Beruri (28.17%) in the state of Amazonas.

[2] The Piagaçu-Purus Sustainable Development Reserve was created by decree 23.723 of 5 September 2003, incorporating the Lago do Ayapuá Environmental Protection Area of the middle Purus River.

[4] On 27 December 2006 the Instituto Nacional de Colonização e Reforma Agrária (INCRA: National Institute for Colonization and Agrarian Reform) recognised the reserve with an area of 617,371 hectares (1,525,560 acres) as meeting the needs of 700 families of rural farmers, who could thus participate in PRONAF.

About 40% of the RDS is floodplain and 60% terra firma forest, but the flat relief and homogeneous vegetation suggest that the dry land has been flooded in the recent past.

The RDS has high biological importance, with great biodiversity of fish and all the known species of aquatic mammals in the Amazon including Amazon river dolphin (Inia geoffrensis), tucuxi (Sotalia fluviatilis), Amazonian manatee (Trichechus inunguis), neotropical otter (Lontra longicaudis) and giant otter (Pteronura brasiliensis).