The river rises in the 342,192 hectares (845,570 acres) Nascentes da Serra do Cachimbo Biological Reserve, a strictly protected conservation unit established in 2005 in the Serra do Cachimbo. It is one of the headwaters of the Xingu River.[2] It flows for 900 kilometres (560 mi) before joining the Xingu, running through the 3,373,133.89 hectares (8,335,195.4 acres) Terra do Meio Ecological Station. The river varies greatly in volume depending on the season, and in the dry season include waterfalls, rocks and rapids.[3]