List of longest undammed rivers


This is a list of the longest undammed rivers of the world, ordered by length.
RiverLengthDrainage areaAverage discharge MouthNotesReferenceRank
Amazon River
Atlantic OceanSecond-longest and largest river in the world, undammed as well as unbridged, does not form a delta while joining the sea due to adequate thrust of river water to overcome the sea water wave and tidal thrusts.1
Lena RiverArctic OceanLongest undammed river in Asia.2
Amur-Shilka-OnonStrait of Tartary3
Amu Darya-PanjAral Sea Although undammed, heavy diversion through canals causes the river to frequently dry up without reaching its mouth. Tajikistan is planning to build a hydroelectric dam on the Panj River.4
Mackenzie-Slave-AthabascaArctic OceanThe Peace-Finlay system would extend even longer from the head of the Slave but there are dams on the Peace.5
Nizhnyaya Tunguska RiverYenisei RiverThe Russian government is planning to build hydro dams on the river within the next few years.
Salween RiverAndaman SeaLongest undammed Southeast Asian river. Burma is planning to build the Tasang Dam and several others.
Paraguay RiverParaná River
Aldan RiverLena River
Rio NegroAmazon River
Vitim RiverLena River
Indigirka RiverArctic Ocean
Fraser RiverPacific Ocean
Kuskokwim RiverBering Sea
Back RiverArctic Ocean
Anadyr RiverGulf of Anadyr
Liard RiverMackenzie River
Yellowstone RiverMissouri RiverLongest undammed river in the contiguous United States.
Maya RiverAldan River
Fly RiverGulf of PapuaLargest completely undammed river system in the world-
White RiverMissouri River--
Tanana RiverYukon River
Thelon RiverHudson Bay
Salmon RiverSnake River
Stikine RiverPacific Ocean
Skeena RiverPacific Ocean
Susitna RiverPacific OceanAlaska is planning to build a hydroelectric dam on the river at Devil's Canyon.