Introduction

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2008–3005

January 2008

Transport of Water, Carbon, and Sediment 

Through the Yukon River Basin

Printed on recycled paper

In 2001, the U.S. Geological Survey 

(USGS) began a water-quality study of 

the Yukon River. The Yukon River Basin 

(YRB), which encompasses 330,000 square 

miles in northwestern Canada and central 

Alaska (fig. 1), is one of the largest and 

most diverse ecosystems in North America. 

The Yukon River is more than 1,800 miles 

long and is one of the last great uncontrolled 

rivers in the world, and is essential to 

the eastern Bering Sea and Chukchi Sea 

ecosystems, providing freshwater runoff, 

sediments, and nutrients (Brabets and 

others, 2000). Despite its remoteness, 

recent studies (Hinzman and others, 2005; 

Walvoord and Striegl, 2007) indicate the 

YRB is changing. These changes likely 

are in response to a warming trend in air 

temperature of 1.7°C from 1951 to 2001 

(Hartmann and Wendler, 2005). As a result 

of this warming trend, permafrost is thawing 

in the YRB, ice breakup occurs earlier on 

the main stem of the Yukon River and its 

tributaries, and timing of streamflow and 

movement of carbon and sediment through 

the basin is changing (Hinzman and others, 

2005; Walvoord and Striegl, 2007). 

One of the most striking characteristics 

in the YRB is its seasonality. In the YRB,

more than 75 percent of the annual 

streamflow runoff occurs during a five 

month period, May through September. 

Yukon Flats near Ft. Yukon. The Black River (high 

DOC) mixing with the sediment-laden water of the 

Porcupine River during peak flow in June

Figure 1. Location of the Yukon River Basin in Canada and Alaska. 

This is important because streamflow determines when, where, and how much of 

a particular constituent will be transported. As an example, more than 95 percent 

of all sediment transported during an average year also occurs during this period 

(Brabets and others, 2000). During the other 7 months, streamflow, concentrations 

of sediment and other water-quality constituents are low and little or no sediment 

transport occurs in the Yukon River and its tributaries.

Streamflow and water-quality data have been collected at more than 50 sites 

in the YRB (Dornblaser and Halm, 2006; Halm and Dornblaser, 2007). Five sites 

have been sampled more than 30 times and others have been sampled twice during 

peak- and low-flow conditions as part of synoptic sampling campaigns. Although 

the synoptic data do not provide a complete picture of water quality of a particular 

river through the year, the data do provide a snapshot of water-quality conditions at 

a particular time of year.

Two constituents of interest are suspended sediment and dissolved organic 

carbon (DOC). Suspended sediment is important because elevated concentrations 

can adversely affect aquatic life by obstructing fish gills, covering fish spawning 

sites, and altering habitat of benthic organisms. Metals and organic contaminants 

also tend to adsorb onto fine-grained sediment. Permafrost thawing has major 

implications for the carbon cycle. It is critical to understand the processes related 

to the transport of DOC to surface waters and how long-term climatic changes may 

alter these processes (Schuster and others, 2004). 

168o 160o 152o 144o 136o 128o 176o 180o 176o 120o 112o 160o 168o

68o

64o

60o

56o

Arctic Ocean

Canada Alaska

British

Columbia

Northwest Territories

Russia

Bering Sea

Chukchi

Sea

Yukon 

Territory

Yukon River Basin

0

0 150

150

300 Kilometers

300 Miles

Figure 1. Location of the Yukon River Basin.
USGS personnel preparing to sample the Yukon River 

just above Eagle, Alaska

Yukon River at Eagle, Alaska—About 100 miles downstream 

of Dawson, Yukon Territory, the Yukon River flows past the 

town of Eagle, Alaska. From Whitehorse to Eagle, the average 

streamflow of the Yukon River increases about 1 order of 

magnitude to 84,000 ft3

/s, representing about 37 percent of 

the total annual average YRB streamflow (fig. 2). Suspended 

sediment loads increase to nearly 70 percent of the total annual 

average from the YRB (about 45 million tons per year), one 

order of magnitude greater than the Yukon River upstream of 

the White River (fig. 3). This is the first location on the Yukon 

River where annual DOC loads can be calculated: 450,000 

tons per year, representing about 25 percent of the total annual 

DOC load from the YRB (Striegl and others, 2007). DOC 

concentrations were smallest during winter months (less than 

2 mg/L) and highest during mid-May (8.5–14 mg/L), the 

beginning of snowmelt. Relatively large DOC concentrations 

(about 20 mg/L in June 2004 and about 16 mg/L in August 

2004) were measured in the Fortymile River between Dawson 

and Eagle, possibly indicating a significant source of DOC from 

this tributary. 

Figure 2. Relative differences in streamflow in the Yukon River basin as shown by size of river. 

Transport of Water, Carbon, and Sediment

The following description of the suspended sediment, 

DOC, and streamflow characteristics of the YRB starts near the 

headwaters of the Yukon River at Whitehorse, Yukon Territory, 

Canada (fig. 2), about 1,800 miles from the mouth of the Yukon 

River. Suspended sediment, DOC, and streamflow data collected 

since 2001, and historical streamflow and water-quality data, 

were used to explain these characteristics.

Yukon River at Whitehorse, Yukon Territory, Canada—At

Whitehorse (fig. 2), the Yukon River drains less than 4 percent 

of the basin and streamflow averages 8,600 cubic feet per second 

(ft3

/s). Streamflow primarily is through large headwater lakes 

that trap much of the sediment before it enters the Yukon River. 

Suspended sediment concentrations generally are less than 15 

milligrams per liter (mg/L) and the annual suspended sediment 

load is about 0.1 percent (62,000 tons) of the total annual load at 

Pilot Station, Alaska (fig. 3). DOC concentrations generally are 

low in the Yukon River because this part of the YRB contains 

only sporadic masses of permafrost and only a few wetland areas. 

Yukon River at Dawson, Yukon Territory, Canada—At Dawson

(fig. 2), about 1,300 miles from the mouth, the Yukon River drains

almost one-third of the basin and streamflow averages 78,000 

ft3

/s. The major tributaries between Whitehorse and Dawson are 

the Teslin, Pelly, White, and Stewart Rivers. The White River, 

the smallest of these basins, is glacier-fed and has the greatest 

average streamflow (20,000 ft3/s) (fig. 2). Glacier-fed rivers such as 

the White River transport higher amounts of suspended sediment 

than non-glacier-fed rivers. The White River transports 19 million 

tons of suspended sediment per year in the upper part of its 

basin (fig. 3). In comparison, non-glacier-fed rivers, such as the 

Pelly and Stewart Rivers transport 2.5 and 2.0 million tons of 

suspended sediment per year, respectively (fig. 3). Downstream 

of the confluence of the White and Yukon Rivers, the clarity of 

the Yukon River changes dramatically, remaining sediment laden 

for its entire reach to the Bering Sea. Synoptic samples from the 

Teslin, Pelly, White, and Stewart Rivers, and other small tributaries 

showed DOC concentrations at about 5 mg/L in this reach of the 

Yukon River. However, DOC was not measured during the snowmelt 

peak, usually the time of largest DOC concentrations.

0 100 200 300 MILES

0 100 200 300 KILOMETERS

EXPLANATION 

Yukon Flats 

Width of river, in cubic feet per second

0 100,000 200,000 300,000

River

 enipucroP

reviR nilseT

reviR ylleP

reviR etihW

reviR kukuyoK

reviR 

Stewart River

Tanana reviR 

Yukon

naciremA

C keer

elimytroF River

reviR kidnaK

reviR

 kcalB

reviR yelrahC

sseH

keerC 

reviR raladnahC

reviR noitaN

wahS

keerC

reviR antizoT

reviR antizoleM

reviR antiwoN

reviR ikuY

Nulato River

Anvik River

Bonasila River

Innoko River

Lower

Birch 

Creek

Beaver 

Creek

Nenana

River

Ray River

152°

64°

66°

136°

Fort Yukon 

Dawson 

Fairbanks

Nenana

Tanana

Whitehorse 

Carmacks 

Eagle 

Circle

Dalton 

Highway

Bridge 

Pilot 

Station 

Ruby 

Kaltag

CANADA

US
Yukon River at Circle, Alaska—Between Eagle and Circle 

the Yukon River flows through a somewhat narrow stretch of 

the basin. The major tributaries—Nation, Kandik, and Charley 

Rivers—are relatively clear streams in small watersheds, and add 

little suspended sediment to the Yukon River. However, DOC 

concentrations greater than 10 mg/L during June 2003 were 

measured in these tributaries, perhaps indicating the presence 

of wetlands or initial thawing of the permafrost in these basins. 

About 1,100 miles from the mouth of the Yukon River, the town 

of Circle, Alaska, marks the beginning of the Yukon Flats, an 

extensive wetland about the size of Connecticut.

Yukon River at Fort Yukon, Alaska—About 1,000 miles from 

the mouth of the Yukon River, this is the mid-point of the 

Yukon Flats. No major tributaries to the Yukon River are 

between Circle and Fort Yukon. The Porcupine River, the largest 

tributary basin in the YRB (45,000 mi2) enters the Yukon River 

at Fort Yukon and has an average streamflow of 17,100 ft3

/s. 

The Porcupine River basin is underlain mostly by permafrost 

and is a major source of DOC into the Yukon River. Although 

DOC concentrations are less than 2.0 mg/L during the winter, 

large DOC concentrations (28 mg/L) were measured during peak

discharge from spring snowmelt. Measured suspended-sediment 

concentrations have been about 200 mg/L during spring snowmelt,

about one-fifth of the concentrations measured in the White River. 

The Porcupine River’s average annual suspended-sediment 

load (4 million tons per year) is less than one-tenth that of 

the Yukon River at Eagle (fig. 3). However, the annual DOC 

load for the Porcupine River is 139,000 tons per year, which 

increases the DOC load from the Yukon River at Eagle by 25 

percent, suggesting that the Porcupine River is the first major 

source of DOC to the Yukon River.

Yukon River at Dalton Highway Bridge, Alaska—The Yukon 

River exits the Yukon Flats at the Dalton Highway Bridge, about 

800 miles from its mouth. Here, the Yukon River drains about 60 

percent of the YRB with an average streamflow of 119,000 ft3

/s, 

representing about one-half the total annual average discharge 

from the YRB (fig. 2). Major tributaries between the Yukon River 

at Fort Yukon and the Dalton Highway Bridge are the Chandalar 

River, Beaver Creek, and Lower Birch Creek. Concentrations of 

DOC for these tributaries were greater than 10 mg/L, reflecting 

extensive wetlands, organic-rich soils, and possibly thawing 

permafrost of the Yukon Flats region. At the Dalton Highway 

Bridge, suspended sediment loads decrease from a combined 

annual average of 49 million tons at Eagle and at the mouth of 

the Porcupine River to 41 million tons per year (fig. 3). Although 

suspended sediment loads are highly variable, this decrease 

suggests that the Yukon Flats may act as a sediment sink. DOC 

loads, however, are about double that from Eagle at 860,000 

tons per year, suggesting that tributaries such as the Porcupine 

River that enter the Yukon River between Eagle and the Dalton 

Highway Bridge are major sources of DOC to the Yukon River.

Yukon River at Ruby, Alaska—At Ruby, about 600 miles from

its mouth, the Yukon River drains about 73 percent of the Yukon 

Basin (259,000 mi2) and has an average streamflow of 167,000 

ft3/s, representing nearly 75 percent of the streamflow from 

the YRB (fig. 2). The Tanana River, a glacier-fed river, is the 

second largest tributary basin (44,300 mi2) and flows into the 

Yukon River about 100 miles upstream of Ruby. Between the 

Dalton Highway Bridge and Ruby, streamflow in the Yukon 

River increases about 37 percent, mostly due to the Tanana River 

(average streamflow 41,400 ft3/s) (fig. 2). Other major tributaries 

are Hess Creek, and the Tozitna, Nowitna, and Melozitna Rivers. 

DOC concentrations measured at these sites were greater than 

10 mg/L, indicating this part of the Yukon River may be a 

Figure 3. Relative differences in suspended sediment load in the Yukon River basin as shown by size of river.

USGS personnel sampling the Yukon River just 

above the Dalton Highway bridge

EXPLANATION

0 20 40 60 80

Yukon Flats

Suspended-sediment load,

in million tons per year

0 100 200 300 MILES

0 100 200 300 KILOMETERS

152°

64°

66°

136° Fort Yukon

Dawson

Porcupine

Fairbanks

Whitehorse

Carmacks

Eagle

Circle

Dalton 

Highway 

Bridge

Teslin River

Pelly River

White River

Pilot 

Station

Ruby Kaltag

River

 River

Stewart River

Tanana River

Yukon

American Creek

Fortymile

Creek

Kandic River

Charley

Ray River

Creek

Hess

Nation River

Shaw 

Creek

Tozitna River

Melozitna River

Nowitna

River

Yuki River

Nulato River

River

Koyukuk

River

Anvik River

Bonasila River

Innoko River

Lower

Birch 

Creek

Beaver 

Creek

reviR raladnahC

reviR

 kcalB

Nenana

River

Tanana

Nenana

CANADA

US
significant source of DOC. The annual suspended sediment load 

of the Tanana River is about 37 million tons, about one-half the 

annual average sediment load from the entire YRB, indicating that 

the Tanana River is a significant source of suspended sediment to 

the Yukon River (fig. 3). The annual DOC load of the Tanana River 

at Nenana is 88,000 tons, much less than the DOC load from the 

Porcupine River, and only about 5 percent of the annual average 

DOC load from the YRB, indicating that this large glacier-fed river 

does not provide a large amount of DOC to the Yukon River.

Yukon River at Kaltag, Alaska—At Kaltag, about 450 miles

from its mouth, the Yukon River drains nearly 90 percent of the 

YRB (296,000 mi2

) and the average annual streamflow represents 

95 percent of the total from the YRB (216,500 ft3

/s) (fig. 2). A 

major tributary to the Yukon River in this area is the Koyukuk River, 

the third largest drainage in the YRB (31,400 mi2

). Other major 

tributaries are the Yuki and Nulato Rivers. Average streamflow 

of the Koyukuk River is about 10 percent of the Yukon River’s 

streamflow at Kaltag (fig. 2). Annual sediment load is 2 million 

tons per year (fig. 3). The Koyukuk River also may be a significant 

source of DOC to the Yukon River. The Koyukuk River is similar 

to the Porcupine River; both basins are underlain by continuous 

permafrost. During spring snowmelt, DOC concentrations were 

greater than 10 mg/L at streamflows greater than 100,000 ft3

/s (June 

2003), similar to the Porcupine River, and provided a large amount 

of DOC to the Yukon River.

Yukon River at Pilot Station, Alaska—The lower reach of the

Yukon River between Kaltag and Pilot Station is in a narrow part 

of the basin and the drainage is increased by only 25,000 mi2

to a total of 321,000 mi2

. Major tributaries between these two 

villages are the Anvik, Bonasila, and Innoko Rivers. The Innoko 

River drains a large wetland area (14,000 mi2

) and measured 

concentrations of DOC were 15 mg/L near peak snowmelt 

discharge in June 2003, indicating this basin may be a significant 

source of DOC to the Yukon River. The Yukon River at Pilot 

Station, about 120 miles from its mouth, is considered the lowest 

reach of the river where streamflow is not affected by the Bering 

Sea. Here, the Yukon River is considered the outflow point for the 

entire YRB. Average streamflow is 227,500 ft3

/s at the Yukon River 

at Pilot Station. Suspended-sediment load averages 74 million tons 

per year and DOC loads average 1.7 million tons per year.

For more information:

USGS Alaska Science Center

4230 University Drive, Suite 201

Anchorage, AK 99508-4650

(907)786-7000 http://alaska.usgs.gov

Authors: Timothy P. Brabets and Paul F. Schuster

Design by: Bill Gibbs

Yukon Flats near Ft. Yukon—Photograph courtesy of Paul 

Schuster, USGS

USGS personnel at Eagle, Alaska—Photograph courtesy of 

Paul Schuster, USGS

USGS personnel at Dalton Highway Bridge—Photograph 

courtesy of Mark Dornblaser, USGS

Banner—Yukon River at Eagle, Alaska. Photograph courtesy 

of Dan Long, USGS

References Cited

Brabets, T.P., Wang, B., and Meade, R.H., 2000, 

Environmental and hydrologic overview of the Yukon 

River Basin, Alaska and Canada: U.S. Geological Survey 

Water-Resources Investigations Report 99–4204, 106 p.

Dornblaser, M.M., and Halm, D.R., 2006, Water and 

sediment quality of the Yukon River and its tributaries 

from Eagle to St. Marys, Alaska, 2002–2003: U.S. 

Geological Survey Open-File Report 2006–1228, 213 p.

Halm, D.R., and Dornblaser, M.M., 2007, Water and 

sediment quality in the Yukon River and its tributaries 

between Atlin, British Columbia, Canada, and Eagle, 

Alaska, 2004: U.S. Geological Survey Open-File Report 

2007–1197, 120 p. 

Hartmann, B., and Wendler, G., 2005, The significance of the 

1976 Pacific climate shift in the climatology of Alaska: 

Climate, v. 18, p. 4824–4839.

Hinzman, L.D., and others, 2005, Evidence and implications 

of recent climate change in northern Alaska and other 

Arctic Regions: Climatic Change, v. 72, p. 251–298.

Schuster, P.F., Reddy, M.M., Aiken, G.R., and Shanley, J.B., 

2004, What effect does permafrost have on dissolved 

organic carbon transport to streams during snowmelt? 

in Wanty, R.B., and Seal, R.R. III, eds., Water-rock 

interaction: Eleventh International Symposium on WaterRock Interaction, WRI-11, Saratoga Springs, New York, 

June 27–July 2, 2004, [Proceedings], p. 1385-1389.

Striegl, R.G., Dornblaser, M.M., Aiken, G.R., Wickland, 

K.P., and Raymond, P.A., 2007, Carbon export and cycling 

by the Yukon, Tanana, and Porcupine Rivers, Alaska, 

2001-2005: Water Resources Research, v. 43, W02411, 

doi:10.1029/2006WR005201, 9 p. 

Walvoord, M.A., and Striegl, R.G., 2007, Increased 

groundwater to stream discharge from permafrost thawing 

in the Yukon River Basin—Potential impacts on lateral 

export of carbon and nitrogen: Geophysical Research 

Letters, v. 34, L12402, doi:10:1029/2007/GL030216.

Summary

The Yukon River provides a daily average of about 228,000 

ft3

/s of water to the Bering Sea. This large North American river

also transports an average of 74 million tons of suspended sediment

and 1.7 million tons of DOC each year (based on a 5-year record, 

2001–05). Downstream of the confluence of the White River and 

the Yukon River, the clarity of the Yukon River changes markedly, 

remaining sediment laden for its entire reach to the Bering Sea. 

The White and Tanana Rivers, the two largest glacier-fed rivers 

in the basin, supply most of the suspended sediment to the Yukon 

River. A number of tributaries are characterized by concentrations 

of DOC greater than 10 mg/L, possibly indicating that these 

streams and rivers may provide significant amounts of DOC to the 

Yukon River. The Porcupine River basin underlain by continuous 

permafrost, contributes about 50 percent more DOC than the 

Tanana River, a basin of similar size underlain by discontinuous 

permafrost. Basins dominated by permafrost or wetlands may be 

the largest contributors of DOC to the Yukon River.