Tributaries include the Aliança and São Pedro rivers.
Part of the river basin is in the 18,715 hectares (46,250 acres) Una Biological Reserve, a strictly protected conservation unit in the Una municipality created in 1980.[1]
In its lower reaches the river flows through the western part of the Una Wildlife Refuge, which surrounds the biological reserve.[2]
At least eight of the tributaries rise in the 11,336 hectares (28,010 acres) Serra das Lontras National Park, created in 2010.[3]