In Mato Grosso the river forms the western boundary of the 164,224 hectares (405,810 acres) Guariba-Roosevelt Extractive Reserve, a sustainable use unit created in 1996.[2] After entering Amazonas the river forms the border between the 83,381 hectares (206,040 acres) Manicoré State Forest, a sustainable use conservation unit created in 2005 and the 72,296 hectares (178,650 acres) Guariba State Park, also created in 2005.[3] The river then runs through the Campos Amazônicos National Park, a 961,318 hectares (2,375,470 acres) protected area created in 2006 that holds an unusual enclave of cerrado vegetation in the Amazon rainforest.[4] It continues north until it joins the Aripuanã River.