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.

Rank	River	Basin countries	Length of longest channel	Drainage area	Average discharge	Average annual discharge	Mouth	Notes
1	Fly	Papua New Guinea Indonesia					Gulf of Papua	Largest river with no dam in its catchment
2	Mamberamo	Indonesia					Pacific Ocean	Indonesia's second largest river after the Kapuas.
3	Sepik	Papua New Guinea Indonesia					Pacific Ocean	Often regarded as largest completely pristine river system in the world
4	Pechora	Russia					Arctic Ocean	Once the subject of a possible transfer of water into the Volga.
5	Atrato	Colombia					Caribbean Sea	Some estimates place discharge much higher - possibly placing the Atrato second only to the Fly
6	Kaladan	Burma India					Bay of Bengal	Discharge estimated in absence of streamgauges. Dredging project by Indian and Myanmar governments.
7	Kikori	Papua New Guinea					Gulf of Papua
8	Khatanga	Russia					Arctic Ocean	Most northerly large river system in the world, with northernmost tree line in basin.
9	Purari	Papua New Guinea					Gulf of Papua	Hydroelectric dam proposed by Queensland government, so may need to be removed from list
10	Pyasina	Russia					Arctic Ocean	Norilsk, most northerly city over 100,000, located on main stem of river.
11	Essequibo	Guyana Venezuela					Caribbean Sea	Largest completely unfragmented river flowing into Atlantic.
12	Anadyr	Russia					Gulf of Anadyr
13	Kuskokwim	Alaska					Bering Sea	Largest unfragmented river in North America. Small dams exist on tributaries of Yukon, with which it shares a major delta.
14	Indigirka	Russia					Arctic Ocean	Oymyakon, often thought of as the Northern Pole of Cold, located on main stem of river.
15	Great Tenasserim	Burma					Andaman Sea	Discharge estimated in absence of streamgauges.
16	Copper	Alaska					Pacific Ocean
17	Stikine	Canada Alaska					Pacific Ocean
18	Taz	Russia					Kara Sea
19	Courantyne	Suriname Guyana					Atlantic Ocean
20	Susitna	Alaska					Pacific Ocean	Hydropower dams proposed at present, so may not remain on list indefinitely
21	Thelon	Canada					Chesterfield Inlet
22	Chari	Chad Cameroon Central African Republic					Lake Chad	Only dryland river with discharge over not affected by dams.
23	Olenyok	Russia					Arctic Ocean
24	Kamchatka	Russia					Pacific Ocean
25	Laluai	Papua New Guinea					Pacific Ocean	Hydropower dams proposed at present, so may not remain on list permanently