List of largest unfragmented rivers


This is a list of the largest river basins without fragmentation by dams in their catchments, ordered by average annual discharge.
To qualify for inclusion, a river must not only have no dams on its “main” stem, but also no dams on any tributary. For this reason, major world rivers such as the Amazon, Lena, Irrawaddy, Amur, and Fraser are disqualified because of dams on tributary streams.
Many of the rivers in this list have uncertain discharges. With the exception of those in Russia, streamgauges have seldom been placed on the majority of the largest unfragmented river systems, due to the remoteness and/or ruggedness of the terrain in which they are located. Apart from the Fly which is clearly the largest, all ranks listed here are not perfectly certain, and there also exist a number of rivers in Sundaland that might qualify with reliable discharge data, such as the Kapuas.
RankRiverBasin countriesLength of longest channelDrainage areaAverage discharge Average annual dischargeMouthNotes
1Fly RiverPapua New Guinea
Indonesia		Gulf of PapuaLargest river with no dam in its catchment
2Mamberamo RiverIndonesiaPacific OceanLargest river in all of Indonesia
3Pechora RiverRussiaArctic OceanOnce the subject of a possible transfer of water into the Volga.
4Sepik RiverPapua New Guinea
Indonesia		Pacific OceanOften regarded as largest completely pristine river system in the world
5Kaladan RiverBurma
India		Bay of BengalDischarge estimated in absence of streamgauges.
Dredging project by Indian and Myanmar governments.
6Kikori RiverPapua New GuineaGulf of Papua
7Khatanga RiverRussia Arctic OceanMost northerly large river system in the world, with northernmost tree line in basin.
8Purari RiverPapua New GuineaGulf of PapuaHydroelectric dam proposed by Queensland government, so may need to be removed from list
9Atrato RiverColombiaPacific OceanSome estimates place discharge much higher - possibly placing the Atrato second only to the Fly
10Pyasina RiverRussia Arctic OceanNorilsk, most northerly city over 100,000, located on main stem of river.
11Essequibo RiverGuyana
Venezuela		Caribbean SeaLargest completely unfragmented river flowing into Atlantic.
12Anadyr RiverRussiaGulf of Anadyr
13Kuskokwim RiverAlaska Bering SeaLargest unfragmented river in North America.
Small dams exist on tributaries of Yukon, with which it shares a major delta.
14Indigirka RiverRussia Arctic OceanOymyakon, often thought of as the Northern Pole of Cold, located on main stem of river.
15Great Tenasserim RiverBurmaAndaman SeaDischarge estimated in absence of streamgauges.
16Copper RiverAlaska Pacific Ocean
17Laluai RiverPapua New Guinea Pacific OceanHydropower dams proposed at present, so may not remain on list permanently
18Stikine RiverCanada
Alaska 		Pacific Ocean
19Taz RiverRussiaKara Sea
20Courantyne RiverSuriname
Guyana		Atlantic Ocean
21Susitna RiverAlaska Pacific OceanHydropower dams proposed at present, so may not remain on list indefinitely
22Thelon RiverCanada Chesterfield Inlet
23Chari RiverChad
Cameroon
Central African Republic		Lake ChadOnly dryland river with discharge over not affected by dams.
24Olenyok RiverRussia Arctic Ocean
25Kamchatka RiverRussiaPacific Ocean