Discharge, in cubic meters per second

Jan. Feb. Mar. Apr. May June July Aug. Oct. Sep. Nov. Dec. 

0.1

1

10

100

1,000

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2020–5059

Prepared in cooperation with the National Park Service

Hydrology and Geomorphology of the Taiya River Near 

the West Creek Tributary, Southeast Alaska
Cover:

Background image: Midriver view of the Taiya River downstream from the Dyea Road bridge and 

upstream from the historical Dyea downtown area, looking downstream, Alaska (photograph by 

Janet Curran, U.S. Geological Survey, August 30, 2017).

Inset images, left to right: Hydrograph showing maximum, mean, and minimum daily discharge 

and peak discharge for period of record for U.S. Geological Survey streamgage on Taiya River, 

Alaska; relative elevation model of Taiya River main stem valley bottom for 2003 conditions, Alaska.
Hydrology and Geomorphology of the 

Taiya River Near the West Creek Tributary, 

Southeast Alaska

By Janet H. Curran

Prepared in cooperation with the National Park Service

Scientific Investigations Report 2020–5059

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DAVID BERNHARDT, Secretary

U.S. Geological Survey

James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2020

For more information on the USGS—the Federal source for science about the Earth, its natural and living 

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Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials 

as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:

Curran, J.H., 2020, Hydrology and geomorphology of the Taiya River near the West Creek Tributary, southeast Alaska: 

U.S. Geological Survey Scientific Investigations Report 2020–5059, 57 p., https://doi.org/10.3133/sir20205059.

Associated data for this publication:

Curran, J.H., 2020, Geomorphic surface and channel boundaries for the lower 7.5 kilometers of the Taiya River Valley, 

southeast Alaska, 2018: U.S. Geological Survey data release, https://doi.org/10.5066/P9XP1SE7.

ISSN 2328-0328
iii

Acknowledgments 

The staff of the National Park Service graciously facilitated field access and provided access to 

geospatial data. Jami Belt of the National Park Service provided significant project coordination 

and field assistance. Rob Schenkert of the U.S. Geological Survey (USGS) and Devon Burton 

of the National Park Service (NPS) assisted with field activities. This project benefitted from 

discussions with Jami Belt, Karl Gurcke, Dave Schirokauer, and Paul Burger of the NPS and 

Robin Beebee, Jim O’Connor, and Louis Sass of the USGS. Joel Cusick of the NPS assisted with 

geospatial data acquisition. Karl Gurcke facilitated access to historical photographs and reports 

from the archives of the Klondike Gold Rush National Historical Park.

Contents

Acknowledgments ......................................................................................................................................iii

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................2

Purpose and Scope ..............................................................................................................................5

Previous Studies ...................................................................................................................................5

Description of Study Area ............................................................................................................................7

Geology and Geography ......................................................................................................................7

Climate and Hydrology.........................................................................................................................8

Methods.........................................................................................................................................................10

Streamflow Data and Flood History Compilation...........................................................................10

Discrete Suspended Sediment Data Collection ............................................................................11

Geomorphic Mapping and Analysis ................................................................................................12

Hydrogeomorphically Dependent Park Resources.......................................................................18

Surface-Water Hydrology and Suspended Sediment ...........................................................................18

Streamflow Since the 1960s..............................................................................................................18

Decadal-Scale Change.............................................................................................................18

Comparisons Between West Creek and Taiya River Discharge........................................20

Large Floods Since the 1800s............................................................................................................20

Suspended Sediment .........................................................................................................................24

Geomorphology............................................................................................................................................24

Valley and Main Stem Channel Geomorphology ...........................................................................28

Active Main Stem ......................................................................................................................28

Abandoned Fluvial Surfaces....................................................................................................33

Alluvial Fans................................................................................................................................33

Emergent Tidal Flats ..................................................................................................................34

Historical Channel Change................................................................................................................34

Channel Change 1894–1948......................................................................................................34

Channel Change Since 1948.....................................................................................................34

Sediment Sources...............................................................................................................................38

Off-Main-Stem Channels...................................................................................................................41
iv

Selected Hydrogeomorphically Dependent Resources........................................................................46

River Recreation..................................................................................................................................46

Boreal Toad Habitat............................................................................................................................46

Sites Near Eroding Banks .................................................................................................................46

Hydrogeomorphic Implications for Taiya River Resources ..................................................................48

Evolution of Valley Bottom Surfaces and Channels......................................................................48

Streamflow and Sediment Timing and Seasonality ......................................................................50

Wetland Water Sources ....................................................................................................................50

Monitoring Considerations................................................................................................................51

Summary and Conclusions.........................................................................................................................52

References Cited..........................................................................................................................................54

Appendix 1. Geographic Information System Digital Files ................................................................57

Figures

1. Taiya River Basin and Lynn Canal, southeast Alaska, and Taiya River Basin and

West Creek subbasin drainage basins, Klondike Gold Rush National Historical

Park, mapping area, and selected streamgages, southeast Alaska....................................3

2. Main stem Taiya River valley bottom and mapping area, Alaska.........................................6

3. Elevation and locations of features within the most developed part of the main

stem Taiya River valley bottom, Alaska.....................................................................................9

4. Dates for periods of daily discharge and peak discharge record, and dates of

suspended sediment sampling, through water year 2019 at U.S. Geological

Survey streamgages at West Creek and the Taiya River, Alaska.......................................10

5. Hydrographs showing maximum, mean, and minimum daily discharge and peak

discharge during the period of record for U.S. Geological Survey streamgages

on West Creek and Taiya River, Alaska...................................................................................11

6. Examples of geospatial products used for geomorphic mapping and an example

completed geomorphic map for a section of the mapping area in the Taiya River

valley, Alaska...............................................................................................................................15

7. Mean annual discharge for each year through water year 2017 at U.S.

Geological Survey streamgages at West Creek and Taiya River, Alaska .........................19

8. Mean daily discharge for the Taiya River at U.S. Geological Survey streamgage

15056210, Alaska, water years 1970–77 and water years 2004–17.....................................20

9. Normalized mean daily discharge for West Creek at U.S. Geological Survey 

streamgage 15056200 and the Taiya River at USGS streamgage 15056210, Alaska,

for the common period of record, water years 1970–77 ......................................................20

10. Orthophotograph and oblique aerial photographs showing 2002 West Creek

glacial lake outburst flood setting and effects ......................................................................21

11. Historical aerial photograph looking south down the Taiya River, Alaska main

stem taken in 1894 by J.J. McArthur for an international boundary survey.....................23

12. Discrete suspended sediment concentration in relation to measured discharge

at U.S. Geological Survey streamgages West Creek and Taiya River, Alaska,

during periods of record............................................................................................................25

13. Discrete suspended sediment concentration by month and day of sampling for U.S.

Geological Survey streamgages West Creek and Taiya River Alaska, during periods

of record.......................................................................................................................................25
v

14. Relative elevation model of the Taiya River main stem valley bottom showing

height above the water surface of Taiya River and Nourse River, Alaska, for 2003 

conditions.....................................................................................................................................26

15. Combined geomorphic map showing geomorphic surfaces by formative process

and off-main-stem channels of the lower 7.5 kilometers of the Taiya River valley

bottom, Alaska.............................................................................................................................29

16. Stream longitudinal profile for the Taiya River and major tributaries within the

Taiya River main stem valley, Alaska, from 2003 lidar data and active Taiya

River channel and valley bottom widths within the mapping area ....................................30

17. Geomorphic map of the lower 7.5 kilometers of the Taiya River valley bottom,

Alaska, showing geomorphic surfaces by formative process and relative age..............31

18. Photographs of West Creek and Taiya River features, Alaska ...........................................32

19. Photographs from Klondike Gold Rush National Historical Park photo station

CH-14 looking west toward West Creek from AB Mountain above the Taiya River

valley, Alaska ..............................................................................................................................35

20. Changes to the active main stem of the Taiya River between 1948 and 2018 near

the Dyea townsite, Alaska.........................................................................................................36

21. Aerial photographs showing changes to the confluence of West Creek and the

Taiya River, Alaska, 1948–2014. A, 1948, black and white ....................................................37

22. Changes to slough entrance conditions and constraints on slough flow path at

valley kilometers 6.0–7.5, Taiya River, Alaska ........................................................................39

23. Incision inferred from changes in stage for a given discharge at U.S. Geological

Survey streamgage at Taiya River, Alaska .............................................................................40

24. Off-main-stem channels in the lower 7.5 kilometers of the Taiya River valley

bottom, Alaska, and amphibian monitoring sites maintained by the National Park

Service..........................................................................................................................................42

25. Photographs of examples of off-main-stem channels in the Taiya River valley

bottom, Alaska.............................................................................................................................45

26. Photograph showing large woody debris in mid-channel, Taiya River, Alaska ...............47

27. Photographs showing a boreal toad adult and metamorphs in wetlands formed

in abandoned sloughs of the Taiya River, Alaska..................................................................47

28. Mean monthly discharge during April, May, and June, 2012–16, in relation to

mean monthly temperature for the Taiya River at U.S. Geological Survey

streamgage 15056210, Alaska...................................................................................................51
vi

Tables

1. Basin characteristics for drainage basins at USGS streamgages at West Creek

(15056200) and the Taiya River (15056210), Alaska..................................................................8

2. Data sources used for mapping and interpretation of geomorphic features in the

Taiya River Basin, Alaska ..........................................................................................................13

3. Descriptions of geomorphic surfaces mapped for the lower 7.5 kilometers of the

Taiya River valley bottom, Alaska ............................................................................................16

4. Definitions of attributes for off-main-stem channels mapped for the lower 7.5

kilometers of the Taiya River valley bottom, Alaska .............................................................17

5. Differences in mean monthly and mean annual discharge between water years

1970–77 and water years 2004–17 for the Taiya River, Alaska, at U.S. Geological

Survey streamgage 15056210 ...................................................................................................19

6. Attributes of off-main-stem channels in the lower 7.5 kilometers of the Taiya River

valley bottom, Alaska .................................................................................................................44

Conversion Factors

International System of Units to U.S. customary units

Multiply By To obtain

Length

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft)

kilometer (km) 0.6214 mile (mi)

Area

square kilometer (km2) 247.1 acre

square kilometer (km2) 0.3861 square mile (mi2)

Volume

liter (L) 33.81402 ounce, fluid (fl. oz)

liter (L) 2.113 pint (pt)

liter (L) 1.057 quart (qt)

liter (L) 0.2642 gallon (gal)

cubic meter (m3) 264.2 gallon (gal)

cubic meter (m3) 0.0002642 million gallons (Mgal)

liter (L) 61.02 cubic inch (in3)

cubic meter (m3) 35.31 cubic foot (ft3)

cubic meter (m3) 1.308 cubic yard (yd3)

cubic meter (m3) 0.0008107 acre-foot (acre-ft)

Flow rate

cubic meter per second (m3/s) 70.07 acre-foot per day (acre-ft/d)

meter per year (m/yr) 3.281 foot per year ft/yr)

cubic meter per second (m3/s) 35.31 cubic foot per second (ft3/s)

cubic meter per second (m3/s) 22.83 million gallons per day (Mgal/d)

millimeter per year (mm/yr) 0.03937 inch per year (in/yr)
vii

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F = (1.8 × °C) + 32.

Datums

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Elevation, as used in this report, refers to distance above the vertical datum.

Supplemental Information

Concentrations of chemical constituents in water are given in either milligrams per liter (mg/L) 

or micrograms per liter (μg/L).

Abbreviations

GIS Geographic Information System

IfSAR interferometric synthetic aperture radar

lidar light detection and ranging

NPS National Park Service

NTU nephelometric turbidity units

NWIS National Water Information System

KLGO Klondike Gold Rush National Historical Park

REM relative elevation model

USGS U.S. Geological Survey

VK valley kilometer

WY water year
viii

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Hydrology and Geomorphology of the Taiya River Near the 

West Creek Tributary, Southeast Alaska

By Janet H. Curran

Abstract

The Taiya River flows through the Chilkoot Trail Unit 

of Klondike Gold Rush National Historical Park in southeast 

Alaska, which was founded to preserve cultural and historical 

resources and further understanding of natural processes active 

in the surrounding coastal-to-subarctic basin. Riverine processes exert an important influence on ecologically important 

boreal toad (Anaxryus boreas boreas), salmon [chum salmon

(Oncorhynchus keta), pink salmon (O. gorbushca), and coho 

salmon (O. kisutch)], and eulachon (Thaleichthys pacificus) 

habitats, erosion of the historic ghost town of Dyea and other 

cultural and historical artifacts, and recreational opportunities in the lower 7.5 kilometers (km) of the Taiya River valley 

bottom. Recurrent consideration of hydroelectric development in West Creek upstream of the park since the 1980s has 

included proposals for damming and diverting West Creek, 

which could alter the delivery of water and sediment to this 

section of the Taiya River. To improve understanding of the 

hydrologic dependence of park resources for the purposes 

of guiding effective monitoring and conservation, this study, 

conducted by the U.S. Geological Survey in cooperation with 

the National Park Service, used a review of hydrologic data, 

collection of discrete suspended sediment data, geomorphic 

mapping, and analysis of historical aerial and ground photographs in a reconnaissance of formative geomorphic processes 

and hydrologic conditions in the lower 7.5 km of the Taiya 

River valley bottom.

Streamflow and suspended sediment data collected at 

the U.S. Geological Survey streamgages on the Taiya River 

and West Creek, combined with historical data, document 

conditions consistent with streams draining strongly glacierized basins in Alaska. Suspended sediment concentrations 

from samples collected concurrently over six varying flow 

levels during 2017–18 ranged from 6 to 284 milligrams per 

liter (mg/L) for the Taiya River and 13 to 162 mg/L for West 

Creek, which are similar to or slightly higher than historical 

values. For the common period of record (1970–77), correlation of daily mean discharge between the two streams 

was strongest (Pearson’s r = 0.97) during the prolonged 

May–October high-flow season and weakest (r = 0.90) during the November–April low-flow season, when West Creek 

daily mean discharge was proportionally higher. For the 

Taiya River, streamflow data compared between the available 

periods of record (1970–77 and 2004–17) showed no decadalscale patterns in mean annual discharge but did show a shift 

toward an earlier spring snowmelt pulse. Notable flooding in 

the Taiya River Basin includes glacial lake outburst floods 

from the Nourse River valley prior to and during the 1897–98 

Gold Rush, a 2002 glacial lake outburst flood from the West 

Creek valley, and a 1967 rainfall-generated flood.

Geomorphic mapping identified four categories of surfaces in the valley bottom—active main stem, abandoned main 

stem, alluvial fans, and emergent tidal surfaces. Using the 

maps, main-stem surfaces were subdivided into age categories 

to identify channel migration patterns from prior to 1940s to 

2018. The valley bottom is dominated by active or abandoned 

channels of the Taiya River except at the extensive low-angle 

West Creek fan. The active main stem presently supports a 

mostly single-thread channel with bars and a few sloughs, but 

the channel actively moved and sometimes was braided within 

multiple, wider unvegetated corridors in 1894 and earlier. An 

inventory of 29 off-main-stem channels identified for the study 

indicates that abandoned main stem channels provide local 

topographic lows that can intercept groundwater or sustain 

tributary flow, facilitating the formation of most nonestuarine 

wetlands in the valley and sustaining important boreal toad 

breeding habitat.

Within the active main stem corridor, the channel has 

episodically built and reworked meanders and bars, eroding 

more than one-half of the historic Dyea townsite, in response 

to glacially controlled delivery of water and sediment, flooding, inputs from West Creek, local features including large 

woody debris and beaver dams, and rapid uplift from isostatic 

rebound. West Creek has constructed a large, persistent fan, 

provoked kilometer-scale Taiya River channel change near the 

confluence, constructively added to high-season streamflow 

that affects Taiya River channel migration capacity, disproportionately contributed early-season streamflow, and possibly 

contributed to groundwater levels in the valley bottom. The 

progressive narrowing and stability of the main stem corridor, 

possibly a result of reduction in the magnitude or frequency 

of glacial lake outburst floods or glacial sediment delivery to 

streams, indicates less active future reworking of abandoned 

main-stem surfaces or regeneration of wetland features. The 
2 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

fluvial history of the Taiya River valley bottom collectively 

indicates continued channel change within a limited corridor, 

relative stability in wetland locations but uncertainty in stability of groundwater supply to them, and channel incision and 

extension in response to uplift.

Introduction

The Taiya River drains a 481-square-kilometer (km2) 

basin that extends from glacier-rich 2,500-meter peaks in 

the Coast Mountains of southeastern Alaska to sea level at 

the head of Taiya Inlet, about 3 kilometers (km) northeast of 

Skagway, Alaska (fig. 1). The main stem Taiya River parallels 

the historic Chilkoot Trail in a 1 km-wide, relatively flat-bottomed, steep-sided valley for about 14 km upstream from the 

river’s estuarine mouth. Much of the Taiya River and its valley 

bottom lie within the Chilkoot Trail Unit of Klondike Gold 

Rush National Historical Park, referred to by the National Park 

Service (NPS) acronym KLGO (fig. 1B). The Chilkoot Trail 

Unit includes NPS, municipal, State, and private lands. All but 

a small reach of West Creek, a major tributary that drains 23 

percent of the Taiya River Basin and enters the valley bottom 

4.5 km upstream from the mouth, lies outside KLGO boundaries and is managed by the Municipality of Skagway.

For effective development of management strategies that 

consider the natural processes of the Taiya River valley and 

the potential changes with land use or climate variability, NPS 

expressed a need for information regarding river hydrology 

(Bernatz and others, 2011). Mixed land ownership of the Taiya 

River Basin presents a need for NPS to consider the effects of 

land management by others on a major stream in a national 

park. Hydroelectric proponents have twice proposed damming 

and diverting West Creek for a hydroelectric facility, once in 

the 1980s (R.W. Beck and Associates, Inc., 1982) and again 

in a proposal (Alaska Power Company, 2014) withdrawn in 

2017. Other uses considered for the West Creek basin have 

included recreational, residential, logging, mining, and municipal activities (Municipality of Skagway, 2014). The limited 

nonmountainous land available near Skagway coupled with 

the accessibility, geography, and less-restrictive land ownership status of the West Creek valley indicates that future proposals for land-use changes are likely. The hydrogeomorphic 

effects on the Taiya River and KLGO resources from potential 

hydrologic changes to West Creek are not well understood.

The Chilkoot Trail and former townsite of Dyea, made 

famous during the late 1800s Gold Rush, are a National 

Historic Landmark that provide well-known KLGO historical, 

recreational, and cultural resources in the Taiya River valley. The KLGO foundation statement acknowledges these 

resources but also focuses on fostering “an understanding of 

the physical and biological processes and associated unique 

flora and fauna” of the northern Lynn Canal, a fjord that cuts 

deeply into the Coast Mountains (fig. 1A) and forces the convergence of subarctic, alpine, coastal, and boreal ecosystems 

over a short distance. Taiya Inlet, at the mouth of the Taiya 

River, forms the northernmost and most inland of several 

inlets at the head of Lynn Canal. The species and habitats 

of the Taiya River valley are thus of inherent importance to 

the NPS, charged with conservation of cultural and historical resources and the natural setting within which they occur 

(Bernatz and others, 2011).

The Taiya River valley bottom is largely filled with 

active and abandoned channels, alluvial fans, and estuarine 

surfaces. Estuarine intertidal areas, wetlands, and clearwater 

side channels (valley bottom channels conveying nonturbid 

tributary flow or groundwater discharge to the main stem) in 

the valley bottom provide habitats for ecologically or economically important species including the boreal toad (Anaxryus 

boreas boreas), three species of Pacific salmon [chum salmon 

(Oncorhynchus keta), pink salmon (O. gorbushca), and coho 

salmon (O. kisutch)], and eulachon (Thaleichthys pacificus) 

(Arimitsu and others, 2003; Hood and others, 2006). Cultural 

resources along Taiya River banks include archeological 

sites and culturally significant artifacts, and modern uses of 

the river include recreational activities, such as rafting. The 

Taiya River is listed on the Nationwide Rivers Inventory 

(NRI), a compilation of free-flowing rivers possessing features 

deemed as outstandingly remarkable natural or cultural values 

(National Park Service, 2017), making the stream eligible for 

designation as a Wild and Scenic River. The historical significance of the Taiya River and its ecological importance as a 

corridor motivated this listing, which mandates that Federal 

agencies seek to avoid impacts that would adversely affect 

those values.

To address current management needs and guide planning, NPS sought to understand the dependence of existing 

biological, cultural, and recreational resources of the Taiya 

River valley on hydrologic and geomorphic conditions. As 

part of the Natural Resources Preservation Program, a U.S. 

Geological Survey (USGS) –NPS science partnership, the 

USGS, in cooperation with NPS, conducted a reconnaissance 

study of important hydrologic and geomorphic processes in 

the lower 7.5 km of the Taiya River valley bottom, encompassing the West Creek confluence.
Introduction 3

tac19-5267_fig01b

Lynn Canal Lynn Cana

I

l

cy Strait

Taiya Inlet

Katzehin River

Tagish Lake

Atlin Lake

Taiya River

Ferebee River Chilkoot Inlet

Favorite Channel

Saginaw Ch

Stephens Passage

Chilkat River Lutak

Inlet

Skagway River

Glacier Bay

BRITISH

COLUMBIA

ALASKA

Gustavus

Juneau

Haines

Klukwan

Fraser

Skagway

C

O

A

S T

M

O

U

N

T

A

I

N

S

Halutu Ridge

Takshanuk Mtns

UNITED STATES

CANADA

98

7

2

SKAGWAY

HAINES

HAINES

HOONAH-ANGOON

HOONAHANGOON

HOONAHANGOON

JUNEAU

EXPLANATION

Mapping area

Boundary of Klondike Gold Rush

National Historical Park

Taiya River Basin boundary

West Creek subbasin boundary

Tutshi R

136° 135°30' 135° 134°30' 134°

59°

45'

59°

30'

59°

15'

59°

58°

45'

58°

30'

58°

15'

0 5 10 15 20 MILES

Base from USGS and other digital data sources. Projection: Universal 0 5 10 15 20 KILOMETERS

Transverse Mercator Zone 8N, North American Datum 1983.

A

Figure 1. A, Taiya River Basin and Lynn Canal, southeast Alaska, and, B, Taiya River Basin and West Creek 

subbasin drainage basins, Klondike Gold Rush National Historical Park, mapping area, and selected streamgages, 

southeast Alaska. [USGS, U.S. Geological Survey]
4 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

tac19-5267_fig01a

West Creek

Nelson

Creek

Taiya River

Taiya

Inlet

Nourse River

Skagway River

East Fork Skagway River

Skagway River

Summit Lake

Chilkoot

Trail Unit

Skagway

Dyea

White Pass

Unit

Skagway Unit

Sheep 

Camp

CANADA

UNITED STATES

C

O

A

S T

M

O

U

N

T

A

I

N

S

White

Pass

98

2

15056200

15056210

Skagway

ALASKA

EXPLANATION

Mapping area

Glacier

Boundary of Klondike Gold Rush

National Historical Park

Taiya River Basin boundary

West Creek subbasin boundary

15056200 Streamgage and USGS identifier

0 1 2 3 4 5 MILES

0 1 2 3 4 5 KILOMETERS Base from USGS 5-meter digital elevation model (Alaska) and ARCTICDEM (Canada) 

showing land surface elevations shaded at various intervals. Projection: Universal 

Transverse Mercator Zone 8N, North American Datum 1983.

135°40' 30' 20' 135°10'

59°

45'

40'

35'

59°

30'

B

Figure 1.—Continued
Introduction 5

Purpose and Scope

This report presents the results of a reconnaissance study 

of hydrologic and geomorphic conditions for a mapping area 

consisting of the lower 7.5 km of the Taiya River valley bottom. The full study area consists of the Taiya River Basin, 

especially the upper 6.5 km of the main stem valley bottom 

and the tributary valleys of West Creek, Nourse River, and 

the upper Taiya River, as needed to provide context for more 

detailed assessment of the mapping area. The objectives of the 

study were to assess existing conditions in the mapping area 

as of 2017–19 (depending on the condition considered) in the 

context of hydrologic and geomorphic history and consider 

the potential effects of water and sediment discharge from the 

West Creek tributary to inform NPS resource management. 

This study drew from existing streamflow and sediment data, 

aerial imagery, and high-resolution light detection and ranging 

(lidar) topographic data, supplemented with collection of suspended sediment data and ground observations of landforms 

and processes in the mapping area. Study findings build on or 

expand findings from previous studies (for example, Bernatz 

and others, 2011). This report documents important physical 

processes and conditions, including the timing and amount of 

water and sediment delivery, the geomorphic history of the 

West Creek fan and Taiya River channels, and the distribution 

and hydrologic connectivity of channel forms.

Previous Studies

The USGS has intermittently monitored streamflow, water quality, and sediment characteristics at USGS 

streamgages on West Creek (15056200) and Taiya River 

(15056210) downstream of West Creek (figs. 1 and 2) since 

the 1960s. In addition, the Southeast Alaska Network Freshwater (SEAN) Water Quality Monitoring Program has monitored water-quality characteristics, including turbidity, at the 

USGS Taiya River streamgage since 2011 (Sergeant and Johnson, 2018; data available at https://irma.nps.gov/DataStore/

Reference/Profile/2182282).

The KLGO Natural Resource Condition Assessment 

completed in 2011 (Bernatz and others, 2011) presents a 

systematic and comprehensive summary of KLGO natural 

resources, including hydrologic analyses of data through 

2009. Hydrogeomorphically relevant KLGO resources include 

riparian flora, boreal toads, wetlands, water quality, hydrology, 

proglacial lakes, and ice cover.

Glacial lake outburst flooding associated with dynamic 

glacier conditions in the headwater valleys of the Taiya River 

is discussed in an informal exploration of evidence for preGold Rush glacial lake outburst flooding (Streveler, 1995) 

and an informal geohazards report conducted as part of the 

Geoscientist-in-Parks program (Capps, 2004) that discusses 

Gold-Rush era outburst floods and a 2002 outburst flood in 

West Creek.

Mapping for a reconnaissance ecological inventory of 

KLGO (Paustian and others, 1994) established a general 

framework for understanding Taiya River hydrology and 

geomorphology. The Taiya River main stem valley bottom 

was mapped as an extensive flood plain unit consisting largely 

of glacial outwash terraces; a fan unit including four large, 

high-angle tributary fans near Finnegan’s Point (fig. 2); and an 

uplifted estuary unit near the river mouth that includes river 

delta and glaciomarine sediments. A channel-type assessment 

for the main stem and many smaller streams incorporated 

channel morphology, channel hydraulics, aquatic habitat, and 

fish species present to categorize stream segments. Individual 

main stem segments are described as meandering to braided. 

Abandoned channels were mapped as palustrine or noted to 

contain clearwater side channels conveying discharge from 

small tributaries or shallow flood-plain aquifers. A limitation 

of this mapping is that specific channel locations were based 

on USGS topographic maps, which did not match many main 

stem channel patterns at the time. An additional mapping effort 

(Bosworth, 2000) produced the most recent KLGO wetland 

map, which extended from the West Creek confluence downstream and primarily relied on the National Wetland Inventory.

Subsequent localized studies addressed bank erosion and 

channel processes near Dyea in detail (Inglis and Pranger, 

2002; Richards and others, 2017). Much of the Gold Rush era 

Dyea townsite, including the Dyea town cemetery containing 

remains of native and nonnative individuals, has been undermined by bank erosion and bank collapse and swept away by 

the river. Inglis and Pranger (2002) provide a narrative of river 

migration observed in historical ground photographs from the 

1890s and 1920s and aerial photographs from the 1920s, 1948, 

1970s, and 1990s, characterize Taiya River channel patterns 

as having decadal-scale periods of relative lateral stability 

broken by annual-scale channel change in discrete locations, 

and describe the ongoing isostatic rebound of the region as a 

likely driver of changing tideline location and land uplift/river 

incision. An NPS bank erosion monitoring report (Richards 

and others, 2017) notes that a period of erosion in the 1970s 

prompted the relocation of some human remains and archeological artifacts.
6 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

tac19-5267_fig02

6

7

0

5

4

3

2

1

10

11

12

13

14

8

9

Finnegan’s Point

Taiya River

West Creek

Historical Dyea

downtown area

Dyea Road

Canyon 

City

Nourse River

Taiya River

15056210

15056200

EXPLANATION

15056200

Klondike Gold Rush National 

Historical Park, Chilkoot 

Trail Unit boundary

Mapping area boundary

Valley kilometer

USGS streamgage and 

identifier

6

135°22' 20' 135°18'

59°

36'

34'

32'

59°

30'

Imagery from Esri World Imagery map service, 2014 photography, copyright 2018 Esri and its licensors.

Universal Transverse Mercator Zone 8N, North American Datum 1983.

Taiya Inlet

0 1 2 3 KILOMETERS

0 0.4 0.8 1.2 MILES

Figure 2. Main stem Taiya River valley bottom and mapping area, Alaska. [USGS, U.S. Geological Survey]
Description of Study Area 7

Description of Study Area

The Taiya River Basin is mapped in the national Watershed Boundary Dataset (U.S. Geological Survey and U.S. 

Department of Agriculture, Natural Resources Conservation 

Service, 2013) as Taiya River Basin (162 km2) and two tributary basins, West Creek (112 km2

) and Nourse River (207 km2; 

fig. 1B). However, because the Nourse River is much larger 

and longer (more than 17 km) than the upper part of the Taiya 

River (11 km upstream of the Nourse River confluence) and 

constitutes the hydrologic headwaters of the basin, this report 

considers the river system to be the 14-km-long Taiya River 

main stem reach between the river mouth and the Nourse 

River confluence and three tributaries— West Creek, Nourse 

River, and upper Taiya River. The main stem and upper Taiya 

River total 25 km in length.

During 2013–17, more than 900,000 people visited 

KLGO annually (https://irma.nps.gov/Stats/, accessed August 

9, 2018). Although the Skagway Unit near cruise ship docks is 

a primary draw, recreational resources of the Taiya River 

valley are also considered an amenity and a local economic 

driver. The river is part of the scenic experience of the lower 

Taiya River valley, which has become a popular destination 

for readily accessible bird and wildlife viewing, hiking, biking, horseback riding, and camping in addition to visitation of 

KLGO historical sites. The gentle (nonwhitewater) reach of 

about the lower 5 km of the Taiya River supports guided rafting excursions by several tour operators, a primary commercial use of the river since the 1980s (Buzzell, 2004).

Because the mouth of the Taiya River is an indistinct 

estuarine environment, locations within the study area are 

given as arbitrary valley kilometers (VK) originating at the 

downstream end of the mapping area, which is an arbitrary 

point at the tip of the downstream-most surface not inundated 

by mean higher high tide (the average of the higher of the two 

daily high tides), and extending up the middle of the valley to 

the end of the valley bottom at VK 14. Although mapping was 

extended upstream to VK 7.4 to encompass a locally complex 

channel system, the text generalizes discussion to VK 7.5. 

Most locations are given to the nearest 0.5 VK to indicate a 

general location for orientation rather than describing specific 

feature extents. For the purposes of a stream longitudinal 

profile along the main stem river bottom, locations along the 

channel centerline are given as river kilometers upstream of 

the same arbitrary mapping area end point. The centerline was 

digitized along the center of the main channel as shown in a 

summer 2003 orthophotograph, using spring 2003 lidar data 

assumed to represent the same flow path as a guide where 

vegetation or shadowing obscured channels.

Geology and Geography

The Taiya River Basin is part of the Coast Mountains 

batholith, an extensive band of plutonic and metamorphic 

rocks along the west coast of northern North America. The 

basin is largely underlain by Tertiary granodiorite (Wilson and 

others, 2015). A fault interpreted as a splay of the Chatham 

Strait fault (Gehrels, 2000) extends through Taiya Inlet and the 

main stem Taiya River valley. Pleistocene glaciers occupied 

southeast Alaska, flowing out through pre-existing valleys 

including Lynn Canal (Kaufman and others, 2011). Presentday glaciers cap taller peaks across the basin and merge with 

extensive glaciers along the western side of the basin (fig. 1B), 

collectively covering 29 percent of the Taiya River Basin 

(table 1). The West Creek subbasin has physical characteristics 

and glacier coverage similar to the Taiya River (fig. 1, table 1). 

The basin characteristics in table 1 are for basins originating 

at the USGS streamgages and were developed from methods described in Curran and others (2016). The streamgage 

drainage areas represent 99 percent and 96 percent of the West 

Creek and Taiya River Basins, respectively, and no major 

hydrologic changes occurred between the streamgage and the 

basin mouth, such that streamgage basin characteristics can be 

considered representative of the entire basins.

Isostatic rebound from the release of depression by thick 

glaciers has generated ongoing rapid uplift relative to sea 

level across southeast Alaska. Uplift rates are estimated to 

range from 16 millimeters per year (mm/yr) near the basin 

mouth to 14 mm/yr in the northeastern part of the basin 

(Larsen and others, 2005; Bernatz and others, 2011), generating almost 2 m of uplift since the Gold Rush. In 2003, the 

historical high-tide line located along the southern edge of 

the Dyea townsite (fig. 2) was more than 500 m inland from 

the location of the mean higher high-water elevation of 5.1 

m for tidal epoch 2007–11. River response to uplift in southeast Alaska has included incision when base-level change 

translated into increased channel slope, which increases the 

ability of the river to scour its bed (for example, Mendenhall 

River, Neal and Host (1999)). Base level for the Taiya River 

is sea level and can be thought of as lowering relative to the 

river, although technically the land surface is rising. Sediment 

deposited at the river mouth has created a gently sloping delta. 

As this is uplifted, the river is extended, which could at least 

partly counter the effect of base-level change on channel slope.

Major gravel-bedded streams extend up the basin’s three 

prominent, long valleys to glaciers in the Nourse and West 

Creek subbasins and to the low, glacier-free Chilkoot Pass 

(1,100 m) at the head of the Taiya River. The Nourse River 

valley contains a series of tributary glaciers, associated lakes, 

and intervening stream segments (fig. 1B) and drains through 

a bedrock gorge near the mouth. Bedrock controls the planform and stability of the lowermost 3.5 km of West Creek, 

including two narrow gorge sections. Farther upstream along 

West Creek, a 5.5-km-long sediment-filled valley is flanked 

by mostly untrimmed alluvial fans and holds a narrow active 

stream corridor and adjacent extensive wetland areas lacking 

major topographic channel scars. Throughout most of the sediment-filled Taiya River valley bottom, channel scars preserve 

a history of channel mobility, but 2019 Taiya River channels 

lack the braided character common to many glacial streams 

and are instead relatively stable, single-channel systems. 
8 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

Table 1. Basin characteristics for drainage basins at USGS streamgages at West Creek (15056200) and the Taiya 

River (15056210), Alaska.

[Mean basin elevation: Elevations here are given in meters above NGVD of 1929. Abbreviations: km2, square kilometers; mm, millimeter; m, meter]

Stream Drainage 

area (km2

)

Mean annual 

precipitation 

(mm)

Mean minimum 

January temperature 

(degrees Celsius)

Mean maximum 

July temperature 

(degrees Celsius)

Mean basin 

elevation (m)

Glacier 

coverage 

(percent of 

basin)

West Creek 111 1,880 -13 13 1,000 29

Taiya River 461 1,930 -13 13 1,070 29

During the Gold Rush era, the now abandoned Nelson Slough 

(fig. 3; VK 0-3.5) conveyed a substantial portion of the main 

stem flow and was known as West Branch Taiya River.

Although the Taiya River valley supported hundreds of 

residents and thousands of hopeful prospectors at Dyea and 

the Canyon City and Sheep Camp settlements along the Taiya 

River during the Gold Rush era, these settlements lasted only a 

few years before being reduced to ghost towns when alternate routes to gold fields opened. However, logging to supply 

power for steam locomotive engines for Chilkoot Trail aerial 

tramways substantially removed trees from the Canyon City 

area at the head of the Taiya River main stem (fig. 2) in 1888–

99 (Karl Gurcke, National Park Service, oral commun., 2017), 

and a sawmill operated in the northern part of the mapping 

area from 1948–56 (F. Norris, National Park Service, written 

commun., 1986). Logging documented from 1948 to 1970 

harvested some trees and cut others for access from about 

Finnegan’s Point to West Creek and harvested some trees in 

the Dyea area. Parts of the Taiya River valley were homesteaded after the Gold Rush. As of 2019, except for backcountry campgrounds along the Chilkoot Trail, development in the 

Taiya River valley extends to just north of West Creek. KLGO 

lands within the mapping area occupy an irregular area about 

3 km long south of West Creek (fig. 3) and contain the Dyea 

townsite, a campground, ranger facilities, trails, and additional 

historical sites, including a cemetery. Privately owned parcels 

include clusters along Dyea Road and along West Creek, an 

individual parcel bordering the Taiya River at VK 3.5, and a 

few other isolated parcels elsewhere in the valley bottom. A 

municipal campground borders KLGO lands near VK 1.2.

Dyea Road crosses the Taiya River 11.4 km north of 

Skagway and crosses West Creek another 2.1 km farther 

north. The Taiya River bridge, completed in 1948 (Alaska 

Department of Transportation and Public Facilities, 2010), 

was protected in 1952 by a dike extending upstream from the 

bridge along the left bank (as viewed looking downstream) to 

block a side channel. This dike is presently about 100 m long 

and supports the start of the Chilkoot Trail. The bridge across 

West Creek was first constructed prior to 1979, abandoned as 

structurally deficient in 1988, and replaced in 1992 (Alaska 

Department of Transportation and Public Facilities, 1988, 

2012).

Climate and Hydrology

Temperate maritime conditions prevail in the Taiya 

River Basin, resulting in cool, wet autumns; cold winters; and 

moderate summers (table 1). The Coast Mountains create a 

rain shadow that protects the basin from the more extreme 

coastal precipitation conditions typical in other southeastern Alaska basins. An average of 1,930 millimeters (mm) of 

precipitation fell per year during 1971–2000 (Gibson, 2009). 

Precipitation was distributed primarily as rain in the autumn 

and snow in the winter, exceeding 250 mm per month during 

October–December (Gibson, 2009). The climatic conditions 

of the West Creek subbasin closely match those of the Taiya 

River (table 1).

The USGS collected daily mean discharge data for each 

day (daily discharge) for West Creek for part of water year 

(WY) 1962 and WY1963–77 and for the Taiya River for 

WY1970–77 and WY2004–19. The USGS collected annual 

maximum instantaneous discharge (peak discharge) for 

West Creek during WY1962–77 and for the Taiya River in 

WY1967, 1970–76, and 2002–19. This report uses discharge 

data through WY2017 except where noted. By convention, the 

water year is the 12-month period from October 1 of the previous calendar year through September 30 of the named water 

year. During periods of continuous operation, the streamgages 

recorded subdaily stage, which was translated to subdaily 

discharge using a rating curve in accordance with Rantz and 

others (1982) and averaged to obtain the daily discharge. Prior 

to the present study, the USGS collected 17 suspended sediment measurements in the 1960s at the West Creek streamgage 

and 13 suspended sediment measurements in the 1970s and 

WY2004 at the Taiya River streamgage (fig. 4). All USGS discharge and suspended sediment data referenced in this report 

are available from the USGS National Water Information 

System (NWIS) (U.S. Geological Survey, 2018).

Mean annual discharge for the available period of record 

is 34.6 cubic meters per second (m3

/s) for the Taiya River 

and 9.49 m3/s for West Creek. Both streams exhibit a summer high-flow-dominated seasonal pattern typical of strongly 

glacierized basins in Alaska (Curran and others, 2016). 
Description of Study Area 9

tac19-5267_fig03

Nelson

Slough

Nelson

Creek Taiya River

West Creek

Taiya Inlet

Flow

Historical

Dyea

downtown area

Start of study area

Municipal 

campground

2.5

0

4.5

4

3.5

3

2

1.5

1

0.5

DYEA ROAD

CHILKOOT

TRAIL

DYEA ROAD

NPS campground,

ranger cabin, and

trailhead parking

DY33

DY02

DY03

DY13

DY14

WC02

WC04

15056210

15056200

DY19

TR01

EXPLANATION

6.5

15056200

National Park Service property boundary

Valley kilometer

National Park Service amphibian monitoring site

and identifier

USGS streamgage and identifier

DY13

Elevation, in meters

Taiya River active main stem, year 2003 

14.5

0.5

0 1 KILOMETER

0 0.5 MILE

Base from National Park Service digital elevation model, 2003 data.

Universal Transverse Mercator Zone 8N, North American Datum 1983.

135°22' 21' 135°20'

59°

31'

59°

30'

Figure 3. Elevation and locations of features within the most developed part of the main stem Taiya River valley bottom, 

Alaska. [USGS, U.S. Geological Survey]
10 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

tac19-5267_fig04

Date of data collection

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020

USGS streamgage

Taiya River

(15056210)

West Creek

(15056200)

Daily discharge period of record

Peak discharge period of record

Sediment data collection dates prior to the study

Sediment data collection dates during the study

EXPLANATION

Figure 4. Dates for periods of daily discharge and peak discharge record, and dates of suspended sediment 

sampling, through water year 2019 at U.S. Geological Survey streamgages at West Creek (15056200) and the Taiya 

River (15056210), Alaska. [USGS, U.S. Geological Survey]

The hydrograph of the maximum, mean, and minimum daily 

discharge for the period of record (fig. 5) shows low-flow 

winters followed by a prominent flow increase from spring 

snowmelt that leads into a prolonged period of more slowly 

rising flows associated with high-elevation snowmelt and glacier meltwater runoff (glacier snowmelt and ice melt). Following a crest during late July–early August, mean daily discharge 

slowly declines except for short-duration increases associated 

with autumn rainfall events. The high-flow season extends 

from about May to October, and the low-flow season extends 

from about November to April. The stream is ice covered for 

periods in the winter. Individual years of record contain more 

variability on a daily to weekly basis than long-term means in 

response to short-term precipitation and temperature fluctuations but follow a general pattern close to the long-term 

discharge pattern. Bernatz and others (2011) examined the two 

relatively short periods of Taiya River data available through 

2009; the data show statistically significant increases in the 

proportion of flow arriving in May and June and corresponding decreases for July and August, an earlier spring snowmelt 

pulse onset, and no changes in streamflow magnitude. Bernatz 

and others (2011) also found streamflow timing shifts indicating the influence of phase alternations in the Pacific Decadal 

Oscillation, a pattern of climate variability related to sea 

surface temperature.

Peak discharge for West Creek and the Taiya River has 

occurred as early as June and as late as November but is most 

common in August and September (fig. 5). Likely flood-generating mechanisms for these annual peak discharges include 

glacier meltwater runoff and rainfall for mid-summer peaks 

and rainfall for autumn peaks. Over the period of record, 

peak discharges exceeded the maximum daily discharge for 

the day of occurrence by an average of 30 percent for both 

streams, indicating that although the processes that generate 

peaks are more intense than those associated with typical daily 

discharge, those processes also tend to elevate discharge for 

much of the day.

Methods

To assess the hydrogeomorphic dependence of resources 

in the mapping area, this study examined the historical context 

available from existing documents and data, described current 

conditions through geomorphic mapping, and used aerial photographs, maps, and remote sensing data, field observations, 

streamflow data, and suspended sediment data to support 

interpretations of hydrogeomorphic processes. Lines of investigation included a review of the hydrologic history of West 

Creek and the Taiya River, including glacial lake outburst 

floods, from historical records; reconnaissance of concurrent 

discrete suspended sediment in the two streams using new 

data; documentation of channel migration history and geomorphic features from lidar and aerial photos; examination of 

streamgage data for evidence of incision; and observations of 

current conditions of selected park resources.

Streamflow Data and Flood History Compilation

Streamflow data provided information on seasonality, 

magnitude, and changes to daily discharge and peak discharge 

since the 1960s. Datasets obtained included daily discharge, 

daily and annual statistics for daily discharge, and peak discharge at the West Creek and Taiya River streamgages. Statistical comparisons of discharge between different periods used 

Student’s t-test at the 95-percent confidence level and were 

considered significant for p < 0.05. Pearson’s r coefficients 

were used to assess the similarity of daily discharge patterns 

between streams.

A geomorphically comprehensive view of flooding in 

the Taiya River Basin required consideration of historical 

accounts and geomorphic evidence in addition to streamgage 

data because the streamgage record is short and the deglaciation process can dynamically affect the storage and release 
Methods 11

of water. In addition to USGS streamgage records (U.S. 

Geological Survey, 2018) and reports (Boning, 1972), flood 

information sources include historical accounts of large floods 

in Gold Rush era newspapers (Sacramento Daily Union, 1897; 

The Seattle Post-Intelligencer, 1897), compilations or discussions of pre-gaging flood information (Inglis and Pranger, 

2002; Buzzell, 2004; Municipality of Skagway, 2009; Gurcke, 

2010), investigations of glacial lake outburst floods or flood 

potential in the Taiya River Basin (Post and Mayo, 1971; 

Streveler, 1995; Capps, 2004; Denton and others, 2009), and 

visual interpretations of historical aerial photographs (McArthur, 1894).

Discrete Suspended Sediment Data Collection

Suspended sediment conditions are of interest for understanding the distribution and seasonal use of the Taiya River 

by aquatic organisms and for engineering considerations and 

environmental effects from potential use of West Creek. No 

concurrent measurements on West Creek and Taiya River 

were available for comparison of suspended sediment conditions prior to this study, and previous measurements (fig. 4) 

could not be assumed to represent current conditions. For this 

study, six discrete suspended sediment samples were collected 

from each stream near the USGS streamgages using standard 

USGS methods (Edwards and Glysson, 1999) at a range of 

discharges throughout the study period of October 2017–June 

2018. Discharge measurements collected at the same time as 

sampling provided data for computation of suspended sediment load. Sampling was conducted nearly concurrently 

(within several hours) for the two streams, except for the July/

August 2017 sampling, which occurred on consecutive days 

during a period of relatively stable discharge (daily discharge 

varied by less than 5 percent between sampling days). Discharge conditions at the time of sampling guided selection of 

either the equal discharge increment or equal width increment 

sampling methodology, both of which resulted in depthintegrated samples. Samples were collected at 5–10 locations 

across the stream and composited to ensure a sample representative of the stream cross section. All sediment samples were 

analyzed at the USGS Cascades Volcano Observatory sediment laboratory to determine the sediment concentration and 

percentage of sediment finer than 0.0625 mm (silt and clay). 

The instantaneous discharge measurement and discrete suspended sediment data were published online via the NWIS as 

Water Quality “Field/Lab Samples” (U.S. Geological Survey, 

2018). Instantaneous suspended sediment loads, also known 

as suspended sediment discharge, computed as the product of 

instantaneous discharge and discrete suspended sediment concentration and the appropriate unit conversion factors, were 

also published in NWIS.

tac19-5267_fig05

A. West Creek, USGS streamgage 15056200

B. Taiya River, USGS streamgage 15056210

Discharge, in cubic meters per second Discharge, in cubic meters per second

Jan. Feb. Mar. Apr. May June July Aug. Sep. Oct. Nov. Dec. 

Jan. Feb. Mar. Apr. May June July Aug. Sep. Oct. Nov. Dec. 

Water years for daily discharge: 1963–77

Water years for peak discharge: 1962–77

Water years for daily discharge: 1970–77, 2004–17

Water years for peak discharge: 1967, 1970–76, 2002–17

0.1

1

10

100

1,000

0.1

1

10

100

1,000

EXPLANATION

Maximum daily discharge

Mean daily discharge

Minimum daily discharge

Peak discharge, day of occurrence unknown

Peak discharge

Figure 5. Maximum, mean, and minimum daily discharge and 

peak discharge during the period of record for U.S. Geological 

Survey streamgages on A, West Creek (15056200) and B, Taiya 

River (15056210), Alaska. Values are plotted by calendar year 

rather than water year to avoid breaks in seasonal patterns. 

Peak discharge is plotted as a bar for the month when the day is 

unknown. [USGS, U.S. Geological Survey]
12 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

Bedload transport affects channel scour and deposition and can be an important factor in channel migration and 

aquatic habitat complexity. This study considered bedload 

characteristics and conditions through geomorphic evidence 

discussed in the “Geomorphic Mapping and Analysis” section 

because bedload sampling was not within the scope of this 

study.

Geomorphic Mapping and Analysis

Geomorphic mapping provided a means to identify existing fluvial features and document evidence for historical channel location and geomorphology, and analysis of historical 

streamgage water-surface-elevation data provided an estimate 

of vertical change, which together formed a basis for evaluating the hydrogeomorphic dependence of KLGO resources. 

Geomorphic maps document the distribution of geomorphic 

features and provide a basis for interpretation of the processes 

that shaped the ground surface. The Taiya River main stem 

valley is likely underlain nearly ubiquitously by fluvial deposits, making fluvial process and timing more effective than 

geology for differentiating various parts of the valley bottom. 

For this study, the primary goals of geomorphic mapping were 

to provide a preliminary delineation of the West Creek alluvial 

fan, document Taiya River channel migration in the mapping 

area since the advent of high-resolution aerial photography 

(1948–2018), detect and document the location of channels other than active main stem channels that could provide 

wetland or stream habitat, and provide information regarding 

recent channel activity from which to infer bedload transport 

conditions. In a broader context, the goals of this mapping 

included gaining an understanding of the hydrologically 

important features of the mapping area, the hydrologic connectivity between main stem and off-main-stem environments, 

and the sources of water in abandoned and active side channels. Mapping products consist of (1) a geomorphic surfaces 

map depicting existing surfaces by formative process (main 

stem, tributary, or tidal), subdivided by age category for fluvial 

surfaces, and (2) a map of off-main-stem channels within those 

surfaces. The geomorphic surfaces and off-main-stem channels 

were mapped for 2003 conditions to match available elevation 

data and adjusted to show small areas eroded by the main stem 

by 2018 to better represent present conditions.

Multiple sources and types of data (table 2) provided 

insight at different temporal and spatial scales to support 

geomorphic mapping. A 2003 lidar elevation dataset, reprocessed to a preferred coordinate system and adjusted by the 

vendor to improve vertical accuracy for this project in 2017, 

provided the basis for map delineations. Interpretations of 

surface features were based on the 2003 lidar, a corresponding 

2003 orthophotograph, other aerial photographs or orthophotographs from 1948 to 2018 at near-decadal intervals for part or 

all of the mapping area and georeferenced by NPS, historical 

ground photos from 1894, interferometric synthetic aperture 

radar (IfSAR) elevation data for Alaska, USGS 7.5-minute 

topographic maps, historical maps, and field reconnaissance 

observations during foot surveys and one raft float from 

August 28 to September 1, 2017, and June 16 to 20, 2018. 

Map feature delineations were digitized in a geographic information system (GIS) at a scale of about 1:2000 or by tracing 

slope derivatives prepared from the lidar data.

The 2003 lidar data were viewed in several ways to aid 

feature interpretation and delineation. First, a digital elevation 

model was shaded in 0.5-m elevation bands and draped over 

a hillshade model (fig. 6A) to enhance visibility of geomorphic features while retaining actual elevation data. Second, a 

relative elevation model (REM) map, sometimes referred to 

as height above river map (Jones, 2006) or height above water 

surface map (Carpenter and others, 2012), was created to better visualize patterns in geomorphic features to aid interpretation. The REM map is an elevation model of the main stem 

detrended for the local slope of the Taiya River (and Nourse 

River near the head of the valley). Following procedures in 

Olson and others (2014, appendix E), water-surface elevations along the stream centerline were extracted from the 2003 

lidar digital elevation model (DEM) and used with an inverse 

distance weighting tool in ArcGIS to create a model of the 

weighted average elevations of the nearest Taiya River water 

surfaces for any point across the valley. The original DEM was 

subtracted from this modeled water-surface elevation, which 

slopes at approximately the valley slope, to create the REM. 

The REM map facilitated qualitative analysis of former river 

positions and cross-cutting relations, such as fan trimlines. 

Finally, a slope map was prepared as a derivative of the lidar 

elevation data and then contoured to a range of values using 

ArcGIS tools to guide mapping. The most prominent steep 

slopes in the Taiya River valley are present at streambanks 

and human-modified features like roadway embankments and 

dikes, making slope a definitive and accurate tool for visualizing and delineating channels, a process used successfully on 

other streams (Jones, 2006). By visual trial and error, slope 

contour values were sought that minimized noise but provided 

enough detail to distinguish geomorphic features. The 15-percent slope contour, one of several suitable contour values, was 

selected in part because it is a commonly used steep-slope 

boundary. 
Methods 13

Table 2. Data sources used for mapping and interpretation of geomorphic features in the Taiya River Basin, Alaska.

[Source and publication data: Accessed from internal National Park Service Klondike Gold Rush Historical Park archives except as noted. National Park Service data are accessible at on the Integrated Resource Management Applications (IRMA) Data Store at https://irma.nps.gov/DataStore/ using the Reference Code 

shown. Abbreviations: cm, centimeter; m, meter; NPS, National Park Service; USGS, U.S. Geological Survey; --, not available; n/a, not applicable; 

no., number]

Name or title Year Month/ 

day Description Scale or resolution of acquisition Source and publication date

Elevation data

IfSAR for Alaska 2010–

2012

-- Meso-resolution topographic data 5-m post spacing,

3-m vertical accuracy

USGS (2010-2012), accessed 

from Alaska Division of 

Geological and Geophysical 

Surveys Elevation Portal at 

https://elevation/alaska.gov

Chilkoot Trail and 

White Pass lidar

2003 5/19-

5/20

High-resolution topographic data; 1 m-pixel bare 

earth digital elevation model data displayed 

as hillshade model, color-enhanced elevation 

bands, or slope derivative

1.4- to 1.7-m post 

spacing, 30 cm 

vertical accuracy

Quantum Spatial, Inc. (2017), 

IRMA Reference Code 

2271787 

Ground photographs

International Boundary Commission 

photographs

1894 -- Black and white ground photographs from J.J. 

McArthur survey; Library and Archives Canada 

Nos. PA-37710, PA-162914, PA-162918, PA162919, PA-162920, PA-162925, PA-162926; 

covers valley bottom from West Creek to head 

of main stem valley

n/a McArthur (1894) (See full citation in References Cited)

NPS historical 

ground photograph

1917 -- Black and white ground photograph; KLGO 

Andrew Beirely collection DO-24-1917; covers 

valley kilometers 1.0-2.5

n/a Beirely (1917) (See full citation in References Cited)

Aerial photographs and orthophotographs

USGS aerial photograph1948 7/11 Black and white aerial photograph; photo SEA 80, 

frame 56; georectified by NPS to 2003 Chilkoot 

Trail Orthophoto

1:40,000 U.S. Navy (1948), IRMA Reference Code 1041349

USGS aerial photographs1948 7/5 Black and white aerial photographs; photos SEA 

75, frames 69-71 and SEA 82, frames 70-72; 

not georectified

1:40,000 U.S. Navy (1948), accessed at 

https://earthexplorer.usgs.

gov/

NPS georeferenced 

aerial photograph

1961 June Black and white aerial photograph; HNS 8-10; 

georectified by NPS to 2003 Chilkoot Trail 

Orthophoto

1:12,000 Aeromap (1961), IRMA Reference Code 1041350

NPS georeferenced 

aerial photographs

1970 6/26 Black and white aerial photographs; Roll DTS 

36, 6-17; georectified by NPS to 2003 Chilkoot 

Trail Orthophoto

1:12,000 Aeromap (1970), IRMA Reference Codes 

1041351–5

NPS georeferenced 

aerial photographs

1979 n/a Color infrared aerial photograph mosaic; Roll 79-

28, Flight Line 9, Frames 188, 189, 191, 193; 

georectified by NPS to 2003 Chilkoot Trail 

Orthophoto

1:10,000 Aeromap (1979), IRMA Reference Codes 

1041357–60

NPS georeferenced 

aerial photographs

1992 n/a Color aerial photograph mosaic; flight line 1 and 

2; georectified by NPS to 2003 Chilkoot Trail 

Orthophoto

1:6,000 Walker Aerial Photography 

(1992), IRMA Reference 

Codes 1041318–9

NPS georeferenced 

aerial photograph

1998 5/15 Color aerial photographs; Skagway Entitlement 

Survey, # 1-3; georectified by NPS to 2003 

Chilkoot Trail Orthophoto

1:18,000 Aeromap (1998), IRMA Reference Codes 

1041364–6

Chilkoot Trail Orthophoto2003 7/1 Color aerial orthophoto of KLGO Chilkoot Trail 

Unit

1:12,000 Aeromap U.S. (2008)

DigitalGlobe satellite orthophoto2010 9/21 Color WorldView-2 satellite orthophoto unknown (0.5-m 

pixel resolution)

DigitalGlobe (2010)

DigitalGlobe satellite orthophoto2014 8/1 Color satellite orthophoto, part of Esri World 

Imagery map service

unknown (0.5-m 

pixel resolution)

Esri (2018), accessed at 

https://www.arcgis.com

DigitalGlobe satellite orthophoto2017 3/9 Black and white satellite orthophoto; DigitalGlobe item no. 0577391180101:12,000 DigitalGlobe (2017), accessed 

at https://www.digitalglobe.

com
14 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

Table 2. Data sources used for mapping and interpretation of geomorphic features in the Taiya River Basin, Alaska.—Continued

Name or title Year Month/ 

day Description Scale or resolution of acquisition Source and publication date

DigitalGlobe satellite orthophoto2018 3/25 Color satellite orthophoto; covers valley kilometers 0-2; DigitalGlobe item no. 0577481630101:12,000 DigitalGlobe (2018), accessed 

at https://www.digitalglobe.

com

Maps

Alaska Boundary 

Tribunal topographic map

1904 

(1894 

ground 

date)

n/a Earliest formal survey of the region; Sheet No. 17; 

ground date estimated to be 1894 from features 

depicted and correspondence of location of 

triangulation stations to locations of 1894 International Boundary Commission photographs

1:160,000 Alaska Boundary Tribunal 

(1904), accessed online 

(See full citation in References Cited)

USGS topographic 

map

1951 n/a Topographic map 1:63,000 USGS (1951)

Most channels and the valley bottom margins were drawn 

by tracing 15-percent slope contours and digitizing as needed 

to connect contours. Tracing results in a repeatable, consistently defined line, but it should be noted that the level of 

detail conveyed by tracing is often more than warranted given 

the resolution of the data. Although the steep slope map (areas 

steeper than or equal to 15 percent; fig. 6B) clearly depicts 

steep-sided feature outlines, additional information gleaned 

from aerial photographs (fig. 6C) and field observations was 

required for the interpretation of the formative process and 

relative age of the features (fig. 6D).

Interpretations of geomorphic surface formative process 

and relative age, and off-main-stem channel attributes, relied 

on surface texture, abrupt elevation differences, cross-valley 

slopes, vegetation age and patterns, and presence of water. 

Using present main stem patterns as a guide, geomorphic surfaces were assumed to be abandoned main stem Taiya River 

channels when channel scars with a relatively long radius of 

curvature could be detected. These former channels appeared 

in elevation data as curvilinear troughs, in aerial photographs 

as curvilinear changes in vegetation height or composition, 

and on the slope map as bounded by curvilinear steep areas. 

Groundwater presence was inferred where dark areas representing open water in off-main-stem channels appeared in 

a snow-covered winter image from 2017 (table 2) because 

groundwater generally emerges at a relatively constant temperature that is often warmer than air temperatures in winter. 

Interpretation of vegetation patterns considered the area’s history of alterations by logging and homesteading activities and 

avoided overemphasizing tree-stand age or composition.

The mapping area surfaces were mapped into six geomorphic units (table 3) consisting of fluvial or uplifted estuarine 

surfaces. Main stem surfaces were divided into active and 

abandoned main-stem surfaces and subdivided by relative age 

(active in 2003 versus created by erosion after 2003 or abandoned prior to the 1940s versus after the 1940s, respectively). 

The active main stem is defined here as the suite of major 

channels, bars, islands, and associated minor channels that 

form a nearly continuous unvegetated area, plus major sloughs 

unlikely to contain shallow, low-velocity flow. Sloughs are 

defined here as small channels conveying main-stem water 

across a surface then reentering the main stem downstream. 

Historically active main-stem surfaces were arbitrarily divided 

into recently abandoned and older abandoned surfaces by their 

appearance in the 1948 aerial photograph; essentially bare or 

lightly vegetated surfaces visible in the photograph were estimated to be less than a decade old, establishing the decade of 

the 1940s as the boundary. Any small channels that appeared 

to have developed on an abandoned surface were considered 

part of the surrounding larger surface for the purposes of 

geomorphic surface mapping. Alluvial fans were mapped as a 

single category that included high-angle fans from small tributaries and the low-angle fan from West Creek. Former tidal 

flats uplifted by isostatic rebound and not fluvially reworked 

constituted the only nonfluvial surface category. Because the 

geomorphic mapping focused on the fluvial history of the 

valley, a few small nonfluvial features or human-modified 

features were ignored. Changes in the 15 years since the 2003 

base-map data were partly accommodated by mapping eroded 

areas as an active main stem category (table 3), but abandonment of areas active in 2003 was difficult to determine conclusively. Areas abandoned since 2003 were likely not extensive, 

but their absence on the map does not reflect any assessment 

of the balance between areas eroded and areas abandoned.
Methods 15

tac19-5267_fig06

4.5

4 E

E

A

B

C

D

0 100 200 300 METERS

0 250 500 750 FEET

8

9

10

11

12

13

14

15

16

17

E 6.5

EXPLANATION

Elevation, in meters

Off-main-stem channel

Active main stem surfaces

Main stem active in 2003

Abandoned main stem surfaces

Main stem abandoned between 1940s and 2003

Main stem abandoned prior to 1940s

Other surfaces

Alluvial fan

Valley kilometer

59°

31'

45"

59°

31'

30"

59°

31'

45"

59°

31'

30"

59°

31'

45"

59°

31'

30"

135°21'30" 21'15" 21' 20'45" 135°20'30"

59°

31'

45"

59°

31'

30"

West Creek

Taiya River

Figure 6. Examples of geospatial products used 

for geomorphic mapping and an example completed 

geomorphic map for a section of the mapping area in the 

Taiya River valley, Alaska. A, The 2003 Light Detection 

and Ranging (lidar) data colored at 1-meter intervals to 

enhance feature boundaries in the valley bottom and 

shaded as a hillshade model for valley walls to identify 

geomorphic features. B, A steep slope map created from 

2003 lidar to identify channel banks. Black areas show 

slopes greater than or equal to 15 percent. Contours of 

15-percent slope (not shown) were traced to generate 

boundaries shown in D. C, 2003 aerial orthophotography 

showing the distribution of water and the relative age of 

vegetation. D, The completed geomorphic map including 

several categories of geomorphic surfaces and offmain-stem channels.
16 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

Table 3. Descriptions of geomorphic surfaces mapped for the lower 7.5 kilometers of the Taiya River valley bottom, Alaska.

[Abbreviations: --, no data; km, kilometer]

Geomorphic surface unit Period when active Description Defining characteristics

Active main-stem surfaces

Main stem activated 

between 2003–2018

post-2003 to present Wetted channels and unvegetated bars of the 

Taiya River and West Creek incorporated 

into the main stem since 2003

Wetted channel in 2017 (entire study area) 

or 2018 (southern 2 km of study area) 

but not in 2003

Main stem active in 2003 2003–present Wetted channel and unvegetated to lightly 

vegetated bars of the Taiya River and West 

Creek

Wetted channel and unvegetated to lightly 

vegetated bars in 2003

Abandoned main-stem surfaces

Main stem abandoned between 1940s–20031940s–2003 Former channels and bars of the Taiya River 

and West Creek that were abandoned between 1940s-2003

Wetted channel and unvegetated to lightly 

vegetated bars in 1948, vegetated areas 

in 2003

Main stem abandoned prior 

to 1940s

pre-1940s Former channels and bars of the Taiya River 

and West Creek that were abandoned prior 

to the 1940s

No wetted channel or bars in 1948 or later, 

channel forms evident in topographic 

expression

Other surfaces

Alluvial fan -- Alluvial fans formed by tributaries to the Taiya 

River, includes active channel for smaller 

fans

Fan-shaped footprint, slightly conical, 

radial channel forms or no obvious channels, usually vegetated except in wetted 

channel

Emergent tidal flat -- Uplifted former tidal surfaces not fluvially 

reworked

Relatively smooth surfaces at or near mean 

higher-higher water elevation

An inventory of all major existing channel forms within 

the mapping area, other than the suite of active main stem 

channels, bars, and sloughs, was conducted for a second map. 

Channels were identified as features having two well-defined 

banks, a bed elevation lower than the surrounding surface, and 

a length more than about 100 m. The channels were assigned 

attributes from field and imagery observations that indicated 

connectivity to water sources and sinks (surface-water body 

receiving outflow) and the presence of surface water (table 4). 

Water sources that could be definitively attributed to the channels consisted of surface water, further categorized as main 

stem (readily detectable as turbid from glacial sources) or 

tributary. Where no obvious surface-water connection could be 

detected but water was present, potential water sources could 

include local snowmelt or local precipitation, but the primary 

water source for many of the wetlands, ponds, and intermittent streams in the nonconnected channels was inferred to be 

groundwater discharge. Evidence of groundwater contributions included open leads from likely warmer water in winter 

orthophotos, but confirmation of the presence of groundwater 

would require additional investigation beyond the scope of 

this study. The channels were categorized by origin as an 

abandoned main stem channel, a tributary-affected channel, or 

unknown.

To provide a cursory examination of evidence for vertical 

streambed elevation change (incision or deposition), historical stage data for the USGS Taiya River streamgage were 

analyzed. The balance between vertical uplift, incision, and 

the downstream horizontal migration of river base-level location can be partly quantified by examining streambed change 

inferred from long-term stage-discharge changes (James, 

1991; Smelser and Schmidt, 1998; Juracek and Fitzpatrick, 

2009; Slater and others, 2015; Anderson and Konrad, 2019) 

at the Taiya River streamgage. A streamgage rating curve 

relates the measured stream stage, or water-surface elevation, 

to discharge for a range of discharges and is updated over time 

to accommodate changes in streambed elevation, geometry, or roughness elements. For the Taiya River at the Dyea 

Road bridge, where the channel occupies most of the bridge 

opening, changes in stage for most discharges over time can 

be assumed to equate to changes in streambed elevation. To 

quantify these changes, stage comparison techniques modified 

from Anderson and Konrad (2019) were applied to historical 

discharge measurement records for the Taiya River. For each 

historical discharge through 2019, the difference between 

the historical stage and the stage estimated from the most 

recent rating curve (2016) for the same discharge was computed. When plotted as a time series, these individual historical–recent stage differences show long-term and short-term 

patterns of bed elevation change. For the Taiya River, flows 

were constrained to 7.5–98.1 m3

/s, the maximum ice-affected 

discharge in the data and the mean monthly July discharge, 

respectively. These discharge-based but somewhat arbitrary 

bounds reduced variability in stage potentially attributable to 

the effect of ice at low discharges and vegetation or other cross 

section changes at very high discharges.
Methods 17

Table 4. Definitions of attributes for off-main-stem channels mapped for the lower 7.5 kilometers of the Taiya River valley bottom, 

Alaska.

Category short name and options Definition

Head Surface-water connection conditions at the upstream end of mapped off-main-stem channels

Inaccessible Blocked by sediment, elevated above estimated typical flood levels, or located away from surface-water 

sources

Flowing not blocked by sediment, water flows into channel at least part of the year

Evidence of flow not blocked by sediment, flood debris visible or vegetation absent

Not blocked not blocked by sediment, no flood debris visible or vegetation is present

Unknown not observed during field observations and not visible on aerial imagery

Exit Surface-water connection conditions at the downstream end of mapped off-main-stem channels

Inaccessible blocked by sediment, elevated above estimated typical flood levels, or located away from surface-water 

sources

Flowing not blocked by sediment, water flow exits channel at least part of the year

Not blocked not blocked by sediment, no flood debris visible or vegetation is present

Unknown not observed during field observations and not visible on aerial imagery

wtr_source Water sources observed or inferred for mapped off-main-stem channels

Groundwater groundwater discharge to channel

Main stem active main stem (West Creek or Taiya River) flow entering channel head or mid-channel

Main stem backwater active main stem (West Creek or Taiya River) flow entering channel exit

Off-main-stem channel flow from another off-main-stem channel

Tributary flow from a tributary to West Creek or the Taiya River

None no water source observed or inferred

Unknown water sources or lack of water sources could not be determined

sw_sink Surface-water body receiving off-main-stem channel flow

Main stem drains to a main-stem channel or slough

Off-main-stem channel drains to another off-main-stem channel

Ocean drains to Taiya Inlet

None exit is inaccessible

obs_date Date and source of observations of mapped off-main-stem channel

Date, methods calendar date and data source (field observations, aerial photograph, or orthophotograph)

water_pres Observations of water presence or evidence of flow in mapped off-main-stem channel

Present water observed

Absent no water observed

Evidence of ephemeral presence no water observed, evidence of flow or ponding present

Unknown not observed during field observations and not visible on aerial imagery

Flow Qualitative assessment of streamflow conditions in mapped off-main-stem channel (more than one option 

is possible for variable channels)

Flowing flow was easily visible, water surface elevation was variable

Limited flow flow was detectable in some locations, water surface elevation was relatively flat

Ponded no flow was visually detectable

None no water was present

Unknown not observed during field observations and not visible on aerial imagery

Abandoned Date of abandonment of mapped off-main-stem channel by main stem Taiya River or West Creek

Prior to 1948 not occupied in the 1948 aerial photograph

After 1948 occupied in the 1948 aerial photograph 

n/a associated with a tributary, not the main stem

Unknown conditions ambiguous in the 1948 aerial photograph

form_proc Formative processes associated with mapped off-main stem channel

Main stem formed by active main stem processes by West Creek or the Taiya River

Tributary formed or modified by tributary to West Creek or the Taiya River

Unknown form and location suggest formation by process other than main stem or tributary

Culvert Infrastructure observed at road or trail crossing of mapped off-main-stem channel

Culvert a culvert was present at the road or trail crossing

No culvert no culvert was present at the road or trail crossing

Footbridge a footbridge was present at the trail crossing

No road no road crossed the stream

Unknown the road or trail crossing was not observed during field investigations
18 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

Hydrogeomorphically Dependent Park 

Resources

From discussions with NPS staff and review of available 

literature and summary documents (Hood and others, 2006; 

Bernatz and others, 2011), several KLGO resources were 

considered critically dependent on hydrologic or geomorphic 

conditions in the mapping area. These resources included 

biological resources such as anadromous and resident fish and 

amphibians, cultural resources (including historical sites) and 

archeological resources near potentially eroding banks, and 

recreation. Of these, this project focused on river recreation, 

boreal toad habitat, and sites near eroding banks as the most 

site specific, most dependent on specific flow regimes, and the 

hardest to assess from published literature. This study sought 

to identify hydrologic and (or) geomorphic conditions relevant 

to these resources to help NPS evaluate the sensitivity of the 

resources to present or future river conditions.

Hydrogeomorphic dependent conditions for rafting, the 

most common hydrologically dependent recreational use of 

the Taiya River, were assessed by a single raft float from the 

commonly used, road-accessed launch (VK 4.7) and landing 

(VK 1.6) on August 30, 2017. This float provided access to 

gravel bars and side channels, observations of bank conditions, 

and observations of potential recreational river navigation 

hazards at relatively high-flow conditions (121 m3/s). Informal discussions with local rafting tour company guides at the 

landing on this date and during a site visit on June 18, 2018, 

provided information regarding common river hazards and 

limitations on float-tour operation related to hydrogeomorphic 

conditions.

KLGO identified the locations of several boreal toad 

breeding sites (fig. 3) during KLGO amphibian monitoring 

surveys initiated in 2004 (Surdyk and Waldo, 2018). These 

locations, all within wetlands, were overlain on the geomorphic map to inventory the geomorphic features containing the 

sites. Information from mapping data sources and from field 

observations of hydrologic conditions was used to infer potential water sources for these wetlands.

Existing and proposed NPS infrastructure and cultural 

and historical resources situated near the banks of the Taiya 

River are sensitive to channel migration that results in bank 

erosion. Bank erosion was assessed from the geomorphic 

mapping for this project by onscreen measurements of eroded 

areas mapped as “main stem activated between 2003–2018,” 

by inspection of channel migration implied by areas mapped 

as “main stem abandoned between 1940s–2003” and “main 

stem active in 2003,” and by inspection of 1948 and 2003 

aerial photographs. Additional bank erosion information was 

provided by ground surveys conducted as part of ongoing 

bank erosion monitoring efforts at selected banks by KLGO 

staff (Richards and others, 2017).

Surface-Water Hydrology and 

Suspended Sediment

Glacier-related processes in the West Creek and Nourse 

River basins have been a primary driver of patterns of seasonal 

streamflow, large floods, and sediment delivery in the main 

stem Taiya River since at least the Gold Rush. In addition to 

generating turbid, prolonged summer high flows typical of 

glacierized basins, glaciers in the study area have been associated with the filling and draining of various lakes, which can 

regulate sediment storage and release in addition to facilitating 

outburst floods. Additional hydrologic affects include rainfallrelated flooding and decadal-scale shifts in timing of seasonal 

patterns associated with climate patterns.

Streamflow Since the 1960s

Decadal-Scale Change

The intermittent and relatively short streamgage records 

precluded in-depth trend analysis but permitted comparisons 

of early to late periods. Using data through WY2009, Bernatz 

and others (2011) found no statistically significant difference in mean annual discharge of the Taiya River between 

the respective periods of record in the 1970s and 2000s in a 

Student’s t test. Results of an updated analysis using records 

through WY2017 (fig. 7) (table 5) show that an increase in 

mean annual discharge in the latter period weakly fails to be 

statistically significant (p = 0.073). The same analysis for 

West Creek shows no statistically significant difference in the 

mean annual discharge between the common period of record 

with the Taiya River in the 1970s and the earlier years of West 

Creek record (fig. 7).

More closely examining the seasonal distribution of flow 

for the Taiya River between periods, however, shows discernible changes in flow timing and magnitude for parts of the year 

(table 5, fig. 8). An overlay of the mean daily discharge for the 

two periods (fig. 8) shows a shift in timing of an average of 14 

days toward earlier spring breakup in the more recent period, 

which echoes findings of a statistically significant earlier 

spring pulse onset (sudden increase in discharge associated 

with spring snowmelt) in Bernatz and others (2011). A corresponding statistically significant increase in mean monthly 

discharge for April–June during the WY2004–17 period 

compared to the 1970s period (table 5) is also consistent with 

the Bernatz and others (2011) seasonal fractional flow analysis 

showing a higher percentage of the annual discharge being 

delivered in May and June. Spring and early summer flow 

increases in the more recent period are not fully compensated 

by decreases in other parts of the year (table 5). The decrease 

in flow delivered in July and August reported by Bernatz and 

others (2011) is minor and not statistically significant in the 

present analysis. Winter (December–March) mean monthly 

discharges are slightly higher but not statistically significant or 

weakly not significant in the more recent period.
Surface-Water Hydrology and Suspended Sediment 19

tac19-5267_fig07

Water year

Mean annual discharge, in cubic meters per second

1965 1970 1975 2005 2010 2015 2020

0

10

20

30

40

50

60

70

1960

Taiya River, USGS streamgage 15056210

West Creek, USGS streamgage 15056200

EXPLANATION

Figure 7. Mean annual discharge for each year through water year 2017 

at U.S. Geological Survey streamgages at West Creek (15056200) and Taiya 

River (15056210), Alaska. [USGS, U.S. Geological Survey]

Table 5. Differences in mean monthly and mean annual discharge between water years 1970–77 and water 

years 2004–17 for the Taiya River, Alaska, at U.S. Geological Survey streamgage 15056210. 

[Values are bolded where significant at the 95-percent confidence level. Abbreviations: WY, water year; m3/s, cubic meters per second]

Period Mean discharge, 

WY1970-77 (m3

/s)

Mean discharge, 

WY2004-17 (m3/s)

Difference between mean 

discharges for WY2004-17 and 

WY1970-77 (percent increase)

p-value of 

t-test of 

means

January 2.35 3.70 57 0.068

February 2.71 3.12 15 0.505

March 2.07 2.63 27 0.294

April 3.63 7.68 112 0.006

May 19.6 42.1 115 0.000

June 57.8 79.8 38 0.002

July 100 97.0 -3 0.738

August 98.6 91.7 -7 0.409

September 58.2 63.3 9 0.532

October 22.9 25.5 11 0.578

November 11.5 8.97 -22 0.473

December 4.11 4.46 9 0.775

Annual 32.2 36.0 12 0.073
20 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

tac19-5267_fig08

WY 1970–77

WY 2004–17

Mean daily discharge,

EXPLANATION

in cubic meters per second

Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

Date

0.1

1

10

100

1,000

Figure 8. Mean daily discharge for the Taiya River at U.S. 

Geological Survey streamgage 15056210, Alaska, water years 

1970–77 and water years 2004–17. [WY, water year]

Comparisons Between West Creek and Taiya 

River Discharge

Averaged over the common period of record, West Creek 

mean annual discharge (9.32 m3/s) averaged 29 percent of 

Taiya River mean annual discharge (32.2 m3/s) at the respective streamgages. At the streamgage location, the Taiya River 

includes the combined discharge from both streams adjusted 

by any contributions from or losses to groundwater. Given 

that no major tributaries enter in the short distance between 

the West Creek confluence and the Taiya River streamgage, 

groundwater losses or gains appear unlikely to constitute a 

large part of the discharge at the Taiya River streamgage. The 

potential exists for small but ecologically important contributions of discharge to groundwater that sustains some mapping 

area wetlands, but this could not be quantified for this study.

The similarity in long-term average seasonal discharge 

patterns between the two streams is evident in an overlay of 

normalized mean daily discharge (mean daily discharge for the 

common period of record for each stream normalized by the 

mean annual discharge for the same period for each respective stream) (fig. 9). The Pearson’s correlation coefficient (r) 

computed for the logarithms of daily discharge of the two 

streams is 0.98 for the full common period of record, showing 

similarity also existed at a daily scale. For the seasonal subsets 

of this record, this daily scale correlation between streams is 

closest for the high flow season of May–October (Pearson’s r 

= 0.97). West Creek daily discharge is proportionally higher 

and not as correlated with Taiya River flow from November to 

April (r = 0.90).

tac19-5267_fig09

Water years 1970–77

Mean daily discharge divided by mean annual 

Jan. Feb. Mar. Apr. May June July Aug. Sep. Oct. Nov. Dec. 

discharge for water years 1970–77

0.001

0.01

0.1

1

10

100

West Creek (USGS streamgage 15056200)

Taiya River (USGS streamgage 15056210)

EXPLANATION

Figure 9. Normalized mean daily discharge for West Creek at 

U.S. Geological Survey (USGS) streamgage 15056200 and the Taiya 

River at USGS streamgage 15056210, Alaska, for the common 

period of record, water years 1970–77. The mean daily discharge 

is divided by the mean annual discharge for the common period of 

record for each respective stream.

Large Floods Since the 1800s

Within the available USGS records, the largest flood at 

both streamgages occurred in September 1967, when widespread heavy rains during September 14–15 dropped 130 mm 

of precipitation in Skagway and generated flooding across 

upper Lynn Canal (Boning, 1972). On the Taiya River, the 

flood discharge reached 708 m3/s, which can be given a statistical annual exceedance probability (AEP) of about 0.5 percent, equivalent to a recurrence interval of 200 yrs (using the 

weighted estimate from table 4 of Curran and others, 2016). 

On West Creek, the 1967 flood discharge reached 277 m3/s, 

an AEP of 0.2 percent or a recurrence interval of 500 years 

(weighted estimate, table 4 of Curran and others, 2016). These 

statistical estimates of flood frequency were developed from 

the relatively short streamgage records and exclude glacial 

lake outburst floods (a 2002 gaged West Creek outburst flood 

and historical ungaged outburst floods), which do not occur 

regularly in response to meteorologic processes and therefore 

do not fit a population eligible for this statistical analysis. 

Flood effects recorded for the 1967 flood include extensive 

road repairs from Taiya River flood damage (Boning, 1972).

On July 23, 2002, a lateral moraine at the confluence of 

the two glacial valleys at the head of West Creek (fig. 1B), 

along with a section of the partly saturated, outwash-filled 

eastern tributary valley behind it, failed and discharged sediment-rich flow over the toe of the glacier and into the adjacent 

pro-glacial lake below (fig. 10A, B, and C) (Capps, 2004, 

Denton and others, 2005). The resulting outburst flood damaged property near the West Creek confluence and prompted 

the evacuation of the NPS campground along the Taiya River 

(fig. 10D and E, respectively). The outburst flood discharge 
Surface-Water Hydrology and Suspended Sediment 21

tac19-5267_fig10

135°32' 31'

59°

34'

30"

59°

34'

59°

33'

30"

31'30" 135°30'30"

Location of present dike

Flow

Imagery from Esri World Imagery map service, 

2014 photography, copyright 2018 Esri and its licensors.

Universal Transverse Mercator Zone 8N, 

North American Datum 1983.

2002 failure 

scarp

Sedimentcovered 

glacier

Proglacial 

lake

West Creek

Lateral

moraine

B

C

D

E

A

0 0.2 0.4 0.6 KILOMETERS

0 0.1 0.2 0.3 MILES

Figure 10. Orthophotograph and oblique aerial photographs 

showing 2002 West Creek glacial lake outburst flood setting 

and effects. A, 2014 orthophotograph showing location of 

lateral moraine and tributary valley failure, and sediment 

deposition over glacier and into proglacial lake. Aerial 

oblique photographs showing: B, failure scarp, perched 

tributary valley, and sediment spreading over the glacier 

(view west); C, sediment and ice debris in the proglacial 

lake (view downstream, West Creek in background); D, West 

Creek flooding into residential areas near the edge of the 

Taiya River valley bottom (upstream of the U.S. Geological 

Survey streamgage, fig. 3) and deposit of large woody debris 

at island heads; and, E, Taiya River flooding at parking area 

at downstream end of National Park Service campground. 

Photographs B–E were taken July 23, 2002, by TEMSCO 

Helicopters, Inc. For reference, the location of a riprapped 

dike constructed along West Creek after 2002 is shown in D.
22 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

peaked at 527 m3/s at the Taiya River streamgage, forming the 

second largest peak in the Taiya River peak discharge record. 

A nonoutburst peak that size at the Taiya River streamgage 

would have had an AEP of about 2 percent (or a recurrence 

interval near 50 years). The West Creek peak discharge could 

not be determined at the streamgage location owing to flood 

damage and flooding outside the channel, but Capps (2004) 

estimated a peak discharge of 459 m3/s from comparison to 

pre-flood National Weather Service stage observations. The 

2002 outburst flood peak discharge was much larger than that 

of the 1967 flood at the West Creek streamgage.

The pre-streamgage historical record for the Taiya River 

includes note of a large flood in the 1920s (Inglis and Pranger, 

2002) that could not be verified for this report. For the nearby 

Skagway River, descriptive histories from the early 1900s 

until at least the 1990s note that an October 1943 flood was 

the largest flood in that period (Buzzell, 2004), exceeding the 

1967 and 1981 floods that were the largest in the 1964–86 

USGS Skagway River streamgage record. Given their late 

autumn dates, these Skagway River floods were likely driven 

by rainfall, which could have affected the Taiya River if 

regional in nature, a likely possibility for large rainstorms. A 

Skagway hazard mitigation planning document (Municipality 

of Skagway, 2009) notes a July 1953 flood that washed away 

the Matthews homestead cabin at Dyea and other cabins along 

West Creek. Cumulatively, these documents and data indicate 

that at least one other flood in the first half of the 1900s could 

have been on the order of the 1967 flood.

Older historical flood records include newspaper 

accounts of a September 18, 1897, flood in the upper Taiya 

River known as the Sheep Camp avalanche (Sacramento Daily 

Union, 1897; The Seattle Post-Intelligencer, 1897) or the 

Stone House Flood (Gurcke, 2010). The newspapers reported 

that observers at Sheep Camp along the upper Taiya River 

(fig. 1B) described a loud noise and sudden onset of a flow of 

what is variously described as water, or “land and rocks and 

ice” that swept away tents not on high ground, a toll bridge, 

and log footbridges. The flood was reported to have resulted 

in one fatality. Farther downstream at Finnegan’s Point on 

the main stem of the Taiya River (fig. 2), observers noted that 

the “river rose nearly a foot in two hours.” Most accounts 

described warm weather and heavy rains for a few days to 

weeks prior to the flood and attributed the flood to the formation of “a lake on the glacier” and a section of ice that broke 

off from the glacier upstream and west of the Stone House, 

a prominent large rock described as about 3 km upstream of 

Sheep Camp. The mention of a lake and the ice fracture, the 

locations of which are supported by Capps (2004), indicates 

the flood could have been a glacial lake outburst flood, and 

the description of the event as a slide or avalanche indicates 

the flood could have evolved into a debris flow. Although this 

flood locally affected discharge and sediment along the Taiya 

River upstream of the Taiya River main stem valley, it seems 

unlikely from historical and geomorphic evidence that it was 

large enough to create notable geomorphic effects on the Taiya 

River main stem.

More substantial glacial lake outburst floods emanated 

from the Nourse River valley prior to the Gold Rush. A historical map (Alaska Boundary Tribunal, 1904) depicts a glacier 

extending downstream of the last major tributary in the Nourse 

River valley and shows no lakes. However, tributary moraines 

in the valley bottom interpreted from IfSAR and aerial imagery, and the potential for large lakes to have drained during the 

Little Ice Age (Streveler, 1995), limit confidence in the Little 

Ice Age continuity of the valley glacier, which indicates that 

the series of dynamically changing valley-blocking tributary 

glaciers, moraines, and associated lakes in the valley bottom 

possibly was exposed earlier than the map depicts. Post and 

Mayo (1971) inventoried Alaska glacier-dammed outburst 

floods from historical aerial photography and mapped the 

Taiya River main stem as the inferred route of an undated 

glacier-dammed lake outburst flood originating from a lake 

midway up the Nourse River valley. Various informal studies (Streveler, 1995; Inglis and Pranger, 2002; Capps, 2004) 

have indicated that at least one large historical outburst flood 

resulted from a release of a glacial lake at the downstream 

end of the Nourse River valley. Streveler (1995) noted bouldery deposits between the mouth of the Nourse River and 

Finnegan’s Point as potential evidence of outburst floods and 

presented tree-ring ages of 150 and 250 years before present 

for two surfaces downstream of the Nourse River confluence. 

He postulated a now-absent lake trapped by valley-blocking 

tributary glaciers in the Nourse River as a potential source for 

one or more groups of glacial lake outburst floods in that time 

frame. Collectively, these studies provide evidence of glacial 

lake outburst floods prior to streamgaging but do not specify 

whether the outburst floods occurred as isolated events or were 

recurring annual to multi-annual events.

The indicated influence of Nourse River glacial lake 

outburst floods on the geomorphology of the Taiya River 

main stem has not been comprehensively evaluated. An 1894 

photograph looking down the main stem Taiya River (McArthur, 1894) shows a bare to lightly vegetated plain from the 

mouth of Nourse River canyon to about halfway to Finnegan’s 

Point (fig. 11A), which has been interpreted by informal studies (Inglis and Pranger, 2002; Capps, 2004; Gurcke, 2010) to 

indicate denudation from an outburst flood not long before the 

photo was taken. Inspection of this photograph shows that the 

combined width of channels and unvegetated bars is wider, 

and the number of active channels more numerous, than in 

2003 or 2014 orthophotos. Varying stages of vegetation can 

be seen on longitudinal wedges across the Nourse River fan. 

Within the limitations of the poor print reproduction of this 

photo, no accumulations of large woody debris indicative of 

valley-width-scale forest denudation can be detected. Although 

the number of flow paths has been reduced since 1894, the 

general locations of the Nourse River, upper Taiya River, 

and main stem Taiya River channels have been only slightly 

modified (fig. 11B). Inspection of 2003 lidar data shows that 

the Nourse River fan shape gradually diffuses downvalley, 

such that by about 1.5 km downstream, the elevation contours 

are roughly transverse to the valley. The upper Taiya River is 
Surface-Water Hydrology and Suspended Sediment 23

B. 2014

A. 1894

Figure 11. A, Historical aerial photograph looking south down the Taiya River, Alaska main stem taken in 

1894 by J.J. McArthur for an international boundary survey. Artifacts from poor scan quality include apparent 

small lumps and shadows. Poor lighting in the foreground appears to show bare areas on side slopes that 

are known from other ground photographs to be forested. B, An approximate match of view location and 

angle using Google Earth to display 2014 Digital Globe imagery. The Nourse River enters the Taiya River main 

stem valley bottom from the right in the foreground, and Taiya Inlet is visible in the background.
24 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

slightly incised into the distal margin of this fan. The surfaces 

lack prominent lobes, outsized bars, or current ripples that 

would indicate evidence of extremely large debris flows or 

outburst floods. The disparate ages obtained for abandoned 

fluvial surfaces (Streveler, 1995) indicate that channel mobility was episodic and not capable of reworking the entire valley 

bottom. Using these multiple lines of evidence, an alternative 

explanation to a large, catastrophic outburst flood for the bare 

appearance of the fan and downstream channels is a more 

active channel regime prior to 1894, possibly supported by 

discharge of sediment directly into the Nourse River rather 

than into a lake or by frequent, smaller glacial lake outburst 

floods.

The chance of future glacial lake outburst floods, which 

pose a flooding threat to valley users and infrastructure and a 

possible influence on channel processes, depends in part on 

moraine stability. Bernatz and others (2011) reviewed available data on existing glacial lakes in the Taiya River Basin, 

including an unpublished 2007 survey that identified at least 

two lakes presenting potential outburst flood hazards in the 

Nourse River subbasin. An assessment of moraine structure 

determined that moraine stability did not present an outburst 

hazard at one of these lakes (Denton and others, 2009), but 

water displacement and lake outlet overtopping from sudden 

inputs at existing lakes, and glacial lake outburst flooding from 

new lakes formed during glacier retreat, remains a possibility 

in the Taiya River Basin.

Suspended Sediment

Collectively over the full period of record, the suspended 

sediment measurements captured information for a range of 

discharge magnitudes (fig. 12) and times of year (fig. 13). 

These measurements provide a basic characterization of the 

Taiya River Basin that is consistent with glacier-fed streams, 

where suspended sediment values range from winter background levels that are often high relative to nonglacier-fed 

streams to higher summer levels that fundamentally vary with 

discharge but can also vary substantially with a range of factors, including depletion of residual sediment stores and nonglacial processes within the basin (Jaeger and others, 2017).

Suspended sediment concentrations for the six discrete 

samples collected concurrently on West Creek and the Taiya 

River during WY2017–18 ranged from 13 to 162 milligrams 

per liter (mg/L) for West Creek and 6 to 284 mg/L for the 

Taiya River. The suspended sediment concentrations for a 

given discharge for the study period are slightly higher than 

the average for previous samples (fig. 12). The increase for 

the study period data relative to the 1960s and 1970s data is 

statistically significant in a t-test (p < 0.05) for both streams. 

Although these increases signify some variation in sediment 

processes in the basin, the available data are too limited for 

trend analysis. The concurrent measurements for this study 

show that Taiya River suspended sediment concentrations 

spanned a slightly larger range of values than those measured 

in West Creek during WY2017–18 (fig. 12). The seasonal 

distribution of suspended sediment concentrations over the 

full period of record (fig. 13) was similar in both streams. In 

general, suspended sediment concentrations began to increase 

from relatively low winter levels in May, peaked in summer 

(June, July, or August), and declined throughout the autumn. 

The May–September 2017–18 measurements for both streams 

frequently had higher values than previous measurements. The 

2017–18 and 2004 measurements for both streams and the 

2004 measurements for the Taiya River collectively have earlier peak suspended sediment concentrations (June) than the 

1960s (West Creek) and 1970s (Taiya River) measurements 

(August–September).

Discrete sediment sampling is often supplemented with 

continuous monitoring of turbidity, a related characteristic, to 

improve understanding of sediment conditions. Here, plots of 

turbidity monitoring data collected by SEAN (Sergeant and 

Johnson, 2018) during the study period showed seasonal patterns that were generally consistent with the suspended sediment measurements. Daily mean turbidity increases around 

May and remains relatively high throughout the summer and 

early autumn. The daily mean turbidity never dropped below 

13 nephelometric turbidity units (NTU) during the month of 

July between 2011 and 2017, for example, and spiked briefly 

several times a year to a period-of-record maximum of 1,930 

NTU. Spikes in daily mean turbidity to a maximum of nearly 

400 NTU in 2017 were noted to generally coincide with high 

flow (Sergeant and Johnson, 2018). The strongly fluctuating 

nature of the turbidity data indicates that suspended sediment 

fluctuates on an hourly to daily scale in the Taiya River Basin, 

a common characteristic of glacier-fed streams.

Geomorphology

The formation of the Taiya River valley was strongly 

affected by bedrock and structural geology, which established 

the framework within which geomorphic processes can operate. The valley owes much of its narrow, steep-sided form and 

straight orientation to the erosion of fault-weakened bedrock (Gehrels, 2000; Wilson and others, 2015). Geomorphic 

processes, largely glacial and fluvial, were responsible for 

filling the presently flat-floored valley bottom with sediment 

and leaving a legacy of features that presently facilitate or 

constrain fluvial processes. Abandoned channels visible in the 

REM map of the main stem valley bottom (fig. 14) show that 

the Nourse River near the head of the valley and the Taiya 

River elsewhere have moved across most of the valley except 

where constrained by fans.
Geomorphology 25

tac19-5267_fig12

Measured discharge, in cubic meters per second

0 50 100 150 200

0

100

200

300

400

0 10 20 30 40 50

Discrete suspended sediment concentration, in milligrams per liter

0

50

100

150

200

B. Taiya River (USGS streamgage 15056210)

A. West Creek (USGS streamgage 15056200)

WY 1970–77

WY 2004

WY 2017–18

WY 1963–68

WY 2017–18

EXPLANATION

EXPLANATION

Figure 12. Discrete suspended sediment concentration in 

relation to measured discharge at U.S. Geological Survey 

streamgages, A, West Creek (15056200) and, B, Taiya River

(15056210), Alaska, during periods of record. [WY, water year]

tac19–5267_fig13

Sampling date

Jan. Feb. Mar. Apr. May June July Aug. Sep. Oct. Nov. Dec.

Discrete suspended sediment concentration, in milligrams per liter

0

100

200

300

400

0

50

100

150

200

B. Taiya River (USGS streamgage 15056210)

A. West Creek (USGS streamgage 15056200)

WY 1970–77

WY 2017–18

WY 2004

WY 1963–68

WY 2017–18

EXPLANATION

EXPLANATION

Figure 13. Discrete suspended sediment concentration 

by month and day of sampling for U.S. Geological Survey 

streamgages, A, West Creek (15056200) and, B, Taiya River

(15056210), Alaska, during periods of record. [WY, water 

year]
26 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

tac19-5267_fig14a

Taiya River

Nourse River

14

13

12

11

10

E

E

E

E

E

E

11

12

13

14

15

16

EXPLANATION

Trail

Road

E

8

Wetted channel centerline, 2003

River kilometer

Valley kilometer

Mapping area boundary

Elevation relative to Taiya River or 

Nourse River, in meters

≥10

-5

0

5

0

A 135°21' 20' 135°19'

59°

37'

36'

59°

35'

0 0.5 MILE

0 0.5 1 KILOMETER

Base from National Park Service digital elevation model, 2003 data.

Universal Transverse Mercator Zone 8N, North American Datum 1983.

Figure 14. Relative elevation model of the Taiya River main stem valley bottom showing height above the water surface 

of, A, Taiya River and Nourse River, B, Taiya River, and C, Taiya River, Alaska, for 2003 conditions.
Geomorphology 27

tac19-5267_fig14b

Taiya River 

Taiya River 

West Creek

Nelson Slough

9

8

7

6

5

10

5

4

3

2

1

0

Dyea

E

E

E

E

E

E

E

6

7

8

9

10

11

12

E

E

E

E

E

E

E

0

1

2

3

4

5

6

B 135°21' 20' 135°19' C

59°

34'

33'

59°

32'

135°22' 21' 135°20'

59°

32'

31'

59°

30'

0 0.5 MILE

Base from National Park Service digital elevation model, 2003 data. 0 0.5 1 KILOMETER

Universal Transverse Mercator Zone 8N, North American Datum 1983.

Figure 14.—Continued
28 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

Within the mapping area, a mosaic of fluvial deposits 

of varying age and origin extend downstream to recently 

uplifted tidal flats. An overview of the surface mapping units 

(by formative process without relative ages) and off-mainstem channels is shown in figure 15. Geomorphic surfaces 

and off-main-stem channels are described and shown in more 

detail in the “Valley and Main Stem Channel Geomorphology” 

and “Off-Main-Stem Channels” sections and documented 

as boundaries and attributes in a data release (Curran, 2020; 

see also appendix 1 GIS digital files available at https://doi.

org/10.5066/P9XP1SE7).

Valley and Main Stem Channel Geomorphology

The Taiya River main stem valley bottom maintains a 

relatively constant width from its head near the Nourse River 

confluence to the West Creek confluence, where it abruptly 

widens (figs. 14, 15, and 16). Within the mapping area, this 

width is an average of 720 m upstream of West Creek and 980 

m downstream of West Creek, as measured at 0.5-km intervals (fig. 16). The valley bottom is confined by bedrock walls 

except where tributary streams have formed high-angle alluvial fans, the most prominent of which are four closely spaced 

tributary fans, two on each side of the valley, at Finnegan’s 

Point (figs. 2 and 14) upstream of the mapping area. The steep 

Nourse River alluvial fan fills the head of the valley bottom, 

obscuring any fan from the upper part of the Taiya River, 

and a low-gradient fan from West Creek extends partway 

across the valley bottom. Active main stem channel gradients 

are steepest, exceeding 0.02 meter per meter (m/m), in the 

Nourse River at the head of the Nourse River fan and decrease 

quickly downstream, dropping below 0.01 m/m at the confluence of the Nourse and Taiya Rivers and below 0.005 m/m by 

Finnegan’s Point.

The channel planform of West Creek, Nourse River, and 

Taiya River as of 2014 (the date of the most recent imagery 

for the full mapping area) was generally single channel with 

mid-channel and lateral bars, small vegetated islands, and a 

few long sloughs. The exception to this is a 3-km anastomosing (stable multiple-channeled) reach at the head of the Taiya 

River valley (fig. 2). Locally, the valley wall or large alluvial 

fans control the Taiya River channel location, creating short 

reaches with a particularly straight bank in planform where 

the channel flows against the bedrock valley wall at VK 3.0, 

6.0, and 7.0 (fig. 14B and 14C), and a bend at the paired fans 

at Finnegan’s Point (fig. 14B, VK 9.0 and 10.0), respectively. 

Where not constrained, the stream has formed shorter-radius 

bends in a meander belt no more than 250 m wide upstream of 

the Taiya River bridge and larger-radius meanders in a meander belt about twice as wide downstream. The largest meander 

bend, more than 500 m in amplitude, extends halfway across 

the valley bottom at VK 2.0, the location of the NPS campground and Dyea townsite (fig. 3). The Taiya River reaches 

mean higher high-tide elevation near the Dyea townsite and 

mean sea level at about VK 0.5, downstream of which the 

river floods broadly at high tide but drains in meandering, tidally and fluvially influenced channels at low tide.

Within the mapping area, geomorphic units include active 

and abandoned main stem Taiya River surfaces, each subdivided into two relative ages; alluvial fans from West Creek 

and smaller tributaries; and tidal flats transitioning to upland 

surfaces (fig. 17). These units are described in the following 

subsections.

Active Main Stem

The active main stem mapping unit includes areas active 

in 2003 plus small adjacent areas converted to active main 

stem by erosion by 2018 (fig. 17). Examples of 2017–18 

conditions along West Creek and the Taiya River are shown 

in figure 18. The width of the active channel, which includes 

channels, bars, and islands, within the mapping area averaged 

100 m upstream of West Creek and widened to 170 m downstream, as measured at 0.5-km increments. The channel slope 

averaged 0.0022 m/m over the mapping area but decreased 

downstream, averaging 0.0029 m/m from the upstream end of 

the mapping area to a slight flattening of slope at VK 3.5 and 

0.0015 m/m from VK 3.5 to the downstream end of the mapping area. The sinuosity, or channel length relative to valley 

length, is 1.1 for the mapping area.

Grain sizes on bars or visible in the channel within the 

mapping area exceeded cobbles, defined as a maximum of 

256 mm, only at the West Creek valley margin, where large 

boulders form a cascade at the valley margin and scattered 

boulders are present for about 300 m downstream. Bars along 

West Creek near its mouth and along the Taiya River consist 

chiefly of gravel (defined as greater than 2 mm to a maximum 

of 64 mm) to cobbles with varying amounts of sand. As a general indication of relative grain size between West Creek and 

the Taiya River, and with distance downstream along the Taiya 

River, the diameters of the particles estimated by a visual scan 

as the median size (D50) at the heads of bars in West Creek 

near the mouth (VK 4.5), the Taiya River upstream of West 

Creek (VK 4.8), and the Taiya River near the mouth (VK 

1.6) were in the gravel range (45 mm, 64 mm, and 23 mm, 

respectively, to the nearest half phi scale class). Finer deposits 

included fresh sand to gravel deposits over partly vegetated 

bars and sand ripples more than 0.3 m thick on one backbar 

channel. More formal particle-size measurements would be 

required to accurately quantify D50 for analysis purposes or to 

document the range of sizes present.
Geomorphology 29

tac19-5267_fig15

Dyea

townsite

5.5

2.5

6

6.5

7

0

5

4.5

4

3.5

3

2

1.5

1

0.5

Area

of

complex

channels

7.5

EXPLANATION

6.5

Off-main-stem channel

Active main-stem surfaces

Abandoned main-stem surfaces

Other surfaces

Alluvial fan

Emergent tidal flat

Valley kilometer

135°22' 21' 135°20'

59°

33'

32'

31'

59°

30'

Base from National Park Service digital elevation model, 2003 data.

Universal Transverse Mercator Zone 8N, North American Datum 1983.

0 0.5 1 1.5 KILOMETERS

0 0.2 0.4 0.6 MILES

Taiya River

West Cr

Figure 15. Geomorphic surfaces by formative process and off-main-stem channels of the lower 7.5 kilometers of the Taiya 

River valley bottom, Alaska.
30 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

tac19-5267_fig16

West

reek

WestCree C k

A

B

0

20

40

60

80

100

Distance from mouth of Taiya River, in river kilometers

15 10 5 0

0

200

400

600

800

1,000

1,200 Width, in meters Elevation, in meters

Active channel

Valley bottom

Taiya River

West Creek

Nourse River

EXPLANATION

EXPLANATION

Figure 16. A, Stream longitudinal profile for the Taiya River and 

major tributaries within the Taiya River main stem valley, Alaska, 

from 2003 lidar data and, B, active Taiya River channel and valley 

bottom widths within the mapping area. The stream centerline used 

to generate the profile is shown in figure 14A, B, and C.
Geomorphology 31

tac19-5267_fig17

West Cr

Taiya River

5.5

2.5

6

6.5

7

0

5

4.5

4

3.5

3

2

1.5

1

0.5

Dyea

townsite

EXPLANATION

6.5

Active main-stem surfaces

Main stem activated between 2003 and 2018

Main stem active in 2003

Abandoned main-stem surfaces

Main stem abandoned between 1940s and 2003

Main stem abandoned prior to 1940s

Other surfaces

Alluvial fan

Emergent tidal flat

Trail

Road

Valley kilometer

135°22' 21' 135°20'

59°

33'

32'

31'

59°

30'

DYEA ROAD

CHILKOOT TRAIL

0 0.5 1 1.5 KILOMETERS

0 0.2 0.4 0.6 MILES

Base from National Park Service digital elevation model, 2003 data.

Universal Transverse Mercator Zone 8N, North American Datum 1983.

7.5

Figure 17. Geomorphic map of the lower 7.5 kilometers of the Taiya River valley bottom, Alaska, showing geomorphic 

surfaces by formative process and relative age.
32 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

tac19-5267_fig18

A

C

B

D

E F

Figure 18. West Creek and Taiya River features, Alaska. Photographs from top left: A, view upstream along West 

Creek, showing riprap along the right bank, August 31, 2017; B, view downstream along the Taiya River from the Dyea 

Road bridge, showing recreational rafters, large woody debris, and mid-channel bars, June 19, 2018; C, erosion of the 

right bank in the large meander at valley kilometer (VK) 2.0 actively affecting the Dyea townsite, August 30, 2017; D, 

riprap protects an eroding section of the left bank adjacent to the National Park Service campground, VK 2.0, August 

30, 2017; E, view downstream along the VK 4.5–7.0 slough from the Chilkoot Trail crossing at VK 5.0, June 19, 2018; and 

F, a large pond at the downstream end of a beaver pond complex at VK 5.5, August 30, 2017. All photographs taken by 

Janet H. Curran, U.S. Geological Survey.
Geomorphology 33

Except where the river borders the bedrock valley wall 

(fig. 17), Taiya River banks are composed of easily erodible unconsolidated sediments consisting largely of sand and 

gravel. Well-exposed eroding banks at VK 2.0 (fig. 18C) are 

mostly sand with occasional gravel and are partially lined with 

large woody debris. Bank heights downstream of West Creek 

are typically 1–2 m above the typical summer water surface 

and a maximum of about 5 m. Bank heights are particularly 

low (less than 1.5 m) adjacent to low terraces shown as surfaces abandoned between the 1940s and 2003 at VK 3.5-4.0 

and VK 1.0-1.5 (figs. 14 and 17). The tallest banks exceed 2.5 

m for almost 1 km along the right bank (looking downstream) 

in the large meander at VK 2.0 and for less than 100 m at the 

Taiya River bridge where the channel flows along surfaces 

abandoned before 1948.

The 2003 aerial imagery and study field observations 

show that the active main stem usually includes a prominent 

main channel and additional features that introduced channel 

complexity, including lateral and mid-channel bars and backbar channels. Vegetated islands were most common upstream 

of and at the West Creek confluence and consisted entirely 

of former channels abandoned between the 1940s and 2003 

(fig. 17). The Taiya River has relatively few sloughs but has 

historically maintained them on a decadal scale. Presently, in 

addition to a long slough in the northern half of the mapping 

area (VK 4.5–7.0), which is about 15 m wide and conveys 

substantial main stem flow (fig. 18E), a smaller slough at VK 

1.0 extends several hundred meters across abandoned fluvial 

surfaces near the river mouth (fig. 17).

Large woody debris observed in the active Taiya River 

throughout the mapping area consisted of tree sections or 

intact trees with branches and rootwads stranded as individual pieces or part of accumulations (log jams). Trees were 

observed lodged in the bed in mid-channel, attached to a 

bank and protruding into the channel, and deposited on bars 

or at the mouths of back-bar channels or sloughs. Large jams 

were present upstream of West Creek. Inglis and Pranger 

(2002) documented relict log jams buried in banks and large 

woody debris lining banks near Dyea. The minimal amount 

of large woody debris along the Dyea banks at the time of this 

study and the presence of relatively fresh (branches intact) 

large woody debris elsewhere indicates that wood recruitment is active and wood mobility possible under present flow 

conditions.

Abandoned Fluvial Surfaces

The Taiya River has abandoned former channel areas 

within the mapping area via channel migration or avulsion. 

The abandoned fluvial surfaces have retained channel definition expressed topographically (fig. 14) or through vegetation 

type and relative maturity for decades, with decreasing feature 

definition with age. The more recently abandoned surfaces in 

the study, those surfaces active or lightly vegetated in 1948 or 

later but abandoned by 2003, now consist of a suite of inactive 

channels and bars that are often distinct and extend across 

much of the abandoned surfaces. Vegetation ranges from 

grasses and shrubs to young forests, depending on time since 

abandonment and environmental conditions including tidal 

inundation. Curvilinear breaks in vegetation at former channels are distinct. Older abandoned fluvial surfaces, likely abandoned prior to the 1940s given the level of vegetation by 1948, 

consist of a mosaic of inactive channels and bars that are less 

distinct than those on younger abandoned surfaces. Individual 

channel banks or bar forms can be discerned but generally 

are not continuous except where tributaries or sloughs have 

maintained surface flow after surface abandonment. Upstream 

of VK 5.5, several major former flow paths of the suite of 

main stem channels active in 1894 can be discerned from 

elevation data (fig. 14). Older abandoned surfaces are typically 

fully vegetated and often fully forested. The history of logging and clearing in the Taiya River valley in the past century 

has affected vegetation age and structure, but fluvial surface 

topography is still discernible as sometimes subtle curvilinear 

changes in vegetation along former channels.

Alluvial Fans

Alluvial fans form prominent to subtle disruptions in the 

otherwise relatively consistent downvalley slope of the valley 

bottom. Formed where steeper tributary streams enter the main 

Taiya River valley and deposit coarse sediment in response to 

the change in gradient, these fan-shaped fluvial deposits vary 

in size and steepness depending on the size, gradient, and sediment supply of their tributary streams.

The largest alluvial fan within the mapping area, the West 

Creek fan, is a low-angle (down-fan gradient less than 0.01), 

diffuse feature that extends more than halfway across the Taiya 

River valley bottom and about 2.5 km along the valley bottom (VK 2.2–4.8; fig. 17). West Creek flows through a long, 

narrow, relatively low-angle valley before entering a narrow 

bedrock canyon then debouching onto the fan. West Creek 

presently flows across the northern end of the fan (fig. 3) in a 

single channel but flooded onto inactive fan areas during the 

2002 glacial lake outburst flood, prior to bank reinforcement 

(fig. 10). Notably, no large channels comparable to the present 

size of West Creek appear on the abandoned West Creek fan. 

The fan displays only minor trimlines from the Taiya River.

Several smaller tributaries, including Nelson Creek at 

VK 1.0, have formed smaller, steep fans that protrude a short 

distance (less than 150 m) from the valley wall (fig. 17). Even 

smaller tributaries draining the valley walls have created or 

maintained channels across the valley bottom but have not 

formed fans mappable at the scale of this study.
34 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

Emergent Tidal Flats

Near the river mouth (fig. 17), low surfaces that were 

below the high tide line during the Gold Rush of the late 1800s 

have been subsequently uplifted by the rapid isostatic rebound 

of southeast Alaska (Larsen and others, 2005). These uplifted 

intertidal areas have not been fluvially reworked by the main 

stem Taiya River, resulting in relatively smooth surfaces 

lacking major channel forms (fig. 3). Smaller features present 

include small channels and ridges likely associated with tidal 

currents and coastal aeolian processes. Vegetation consists 

mostly of grasses and salt tolerant plants. Conifers have begun 

to disperse downvalley as land rises, creating a young, sparse 

forest with a strong downvalley age gradient at the upstream 

end of the mapped emergent tidal flat surface.

Historical Channel Change

Abandoned fluvial features fill the width of the main 

stem valley bottom, documenting the historical mobility of the 

Taiya River. Within the mapping area, topographic evidence 

of relict assemblages of long, downvalley-oriented, curved 

channels; shorter, cross-valley channels; and intervening bars 

in some locations indicate the river formerly had multiple 

channels that were free to migrate or braid. Dendritic patterns superimposed on some abandoned main-stem surfaces 

indicate that these surfaces stabilized long enough to develop 

small channel networks conveying groundwater discharge or 

tributary flow. Wide swaths of abandoned channels inset into 

adjacent surfaces indicate that the active river was wider in the 

past. Downstream of West Creek, a history of meandering can 

be seen in a meander belt developing along the eastern side of 

the valley. Photographic evidence from 1894 and 1948 show 

specific channel changes and indicate a reduction in mobility 

since the late 1800s.

Channel Change 1894–1948

Photographs from 1894 (table 1) show a series of forested 

islands in a nearly valley-wide active channel throughout 

much of the Taiya River valley bottom (figs. 11A and 19A). 

Relative to modern conditions (figs. 11B and 19B), the Taiya 

River valley bottom was considerably less vegetated, supported more channel pathways, and had wider active channel belts within those paths. Although the specific cause of 

change is unclear, the river was more actively shifting channels and braiding in some locations at some time prior to 

1894. During the Gold Rush, the Taiya River maintained two 

major branches in the Dyea area; the channel known as the 

West Branch Taiya River and later as Nelson Slough was a 

substantial active channel at the time. An oblique photo from 

the ridge above Dyea (Beirely, 1917) shows that as late as 

1917, the Taiya River actively braided through a wide belt 

including lightly vegetated abandoned surfaces on the eastern 

side of the valley, but the smaller, single-thread Nelson Slough 

occupied a position close to its location in 1948 and all subsequent aerial photography (table 2). By 1948, the active Taiya 

River channel belt had narrowed considerably, abandoning 

major channel pathways and reducing the stream to the single 

main channel pathway still occupied in 2019 (figs. 3 and 17). 

Multiple meander scars and the 1948 channel location between 

VK 1.0 and 1.5 (area of abandoned surfaces in fig. 17) document active meander migration in the lowermost reaches of 

the river prior to 1948.

Channel Change Since 1948

In the second half of the 1900s, reduction in size and 

activity of the channel continued. Compared to 1948 conditions, the Taiya River has maintained the same general location within the mapping area but consolidated from multiple 

channels and frequent bars within a small active channel belt 

to a mostly single-thread channel with fewer bars and an even 

narrower active channel belt. Since 1948, channel change 

consisting mostly of meander migration and meander cutoffs 

affected areas downstream of West Creek, slightly widening 

the modern meander belt and creating abandoned fluvial surfaces (figs. 17, 20, and 21). Other minor channel adjustments, 

mostly development of small meanders, occurred upstream of 

West Creek. Many individual gravel bars elongated, shifted, 

or changed in size but have not changed position since at 

least 1948. Since 2003, relatively little change has occurred 

to the Taiya River channel location. Between 2003 and 2018, 

the Taiya River eroded a total area of 0.07 km2, or less than 1 

percent of the active channel area. Erosion occurred throughout the mapping area (fig. 17), extending a maximum of 150 

m into the bank and spanning reaches mostly less than a few 

hundred meters long but also including a nearly 1-km-long 

reach at VK 1.0.

The location of the West Creek channel within the mapping area has remained essentially fixed upstream of the West 

Creek bridge since 1948. Riprap bank protection, placed 

in association with bridge construction and following the 

2002 glacial lake outburst flood, enforces the path (fig. 18A). 

Immediately downstream of the bridge, however, West Creek 

migrated north after 1948, contributing to erosion of a bar 

separating the channels that forced stream capture of a section 

of West Creek by the Taiya River (fig. 21). The complex channel changes that ensued rearranged the Taiya River, effectively 

straightening a kilometer-long reach and moving the confluence about 200 m upstream.
Geomorphology 35

tac19-5267_fig19

A

B

Figure 19. Photographs from Klondike Gold Rush National Historical Park photo station CH-14 looking west 

toward West Creek from AB Mountain above the Taiya River valley, Alaska. A, 1894 conditions show multiple main 

stem flow paths containing wider suites of active channels. B, August 27, 2013, conditions show the active main 

stem channel has consolidated into a single flow path and narrowed. Photographs, A, by James J. McArthur, 

International Boundary Commission and, B, by R.D. Karpilo, Jr., National Park Service. Modified from AB Mountain 

1 Photo Pair, Chilkoot Trail: Then and Now photo gallery, National Park Service website https://www.nps.gov/klgo/

learn/nature/repeatphotography.htm.
36 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

tac19-5267_fig20

Dyea (Taiya) River (Main or East Branch

W

)

est Branch Dyea River

High tide line

Taiya River

Cemetery BROADWAY (TRAMWAY ROUTE)

MAIN ST. (EAST ST.)

RIVER ST. (EAST ST.)

WEST ST.

SCOW ST.

WATER ST. (OLD POST ROAD)

7TH ST.

6TH ST.

5TH ST.

4TH ST.

3RD ST.

2ND ST.

1ST ST.

FRONT ST.

NATIONAL PARK 

SERVICE 

CAMPGROUND

Nelson

Slough

DY19

DY33

TR01

DY02

DY03

DY13

DY14

1.0

2.5

2.0

1.5

EXPLANATION

6.5

DY13

Paved road

Unpaved road

Trail

Valley kilometer

National Park Service amphibian monitoring site and identifier

Skagway Municipal Campground, Dyea

Main-stem active in 2003

Main-stem activated between 2003 and 2018

National Park Service property boundary

Historical Dyea downtown area

Branch Historical water features SMCD

SMCD

0 100 200 300 METERS

0 250 500 750 FEET

Imagery from USGS aerial photograph georeferenced by National Park Service, 1948 photography. 

Universal Transverse Mercator Zone 8N, North American Datum 1983.

Klondike Gold Rush National Historical Park boundaries, historical map, 

and monitoring data: National Park Service, Anchorage, Alaska.

135°22'30" 135°21' 135°20'30"

59°

31'

30"

59°

30'

00"

Figure 20. Changes to the active main stem of the Taiya River between 1948 and 2018 near the Dyea townsite, Alaska. The historical 

map of Dyea shows the locations of downtown lots and streets and the approximate locations of the West Branch Dyea River (now 

Nelson Slough), the Main or East Branch of the Taiya River (now Taiya River), and the high tide line during the Gold Rush (1897–98). 

Channel patterns in the 1948 aerial photograph indicate that channel migration washed away the southeastern part of the townsite prior 

to 1948.
Geomorphology 37

tac19-5267_fig21

West Creek

Taiya River

4.5

4.0

4.5

4.0

4.5

4.0

E

4.5

4.0

4.5

4.0

A

B

A

B

A

B

A

B

A

B

4.5 Valley kilometer

Location of interest

EXPLANATION

A

0 0.2 0.4 0.6 KILOMETERS

0 0.1 0.2 0.3 MILES

59°

31'

45"

31'

30"

59°

31'

15"

135°21' 20'45" 135°20'30"

59°

31'

45"

31'

30"

59°

31'

15"

135°21' 20'45" 135°20'30" 135°21' 20'45" 135°20'30"

Imagery from USGS aerial photograph georeferenced by National Park Service, 1948 photography; National Park Service color 

infrared aerial photograph, 1979 photography; National Park Service orthophotograph, 2003 photography; National Park Service 

orthophotograph, 2010 photography; Esri World Imagery map service, 2014 photography, copyright 2018 Esri and its licensors.

Universal Transverse Mercator Zone 8N, North American Datum 1983.

D. 2003 E. 2014

A. 1948 B. 1979 C. 1992

Figure 21. Changes to the confluence of West Creek and the Taiya River, Alaska, 1948–2014. A, 1948, black and white. B, 1979, color 

infrared. C, 1992, color. D, 2003, color. E, 2014, color. At the confluence, a bar separating the streams (location A) was eroded away 

by channel bend migration, moving the confluence location upstream and straightening the Taiya River channel. Downstream of the 

confluence, a bend (location B) elongated downstream then was abandoned between 1948 and 1979, reversed curvature by about 

2003, and continued to erode the left bank (looking downstream) between 2003 and 2014.
38 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

Flow in Taiya River sloughs is highly dependent on 

entrance conditions, which changed at some sloughs in 

response to channel migration, uplift, or log jams. Field observations in 2017 showed that the former entrance to Nelson 

Slough was perched above likely river flood stages, indicating 

channel response to some combination of local channel slope 

change from meander cutoffs and valley uplift from isostatic 

rebound. Near the head of the VK 4.5–7.0 slough (fig. 22), 

local Taiya River channel migration and formation of a log 

jam in the main stem between 2003 and 2010 is inferred to 

have reapportioned discharge between the main stem and the 

slough entrances (locations A and B in fig. 22) to generate an 

increase in slough discharge that contributed to damage to 

a Chilkoot Trail bridge farther downstream, near prominent 

beaver ponds (location C in fig. 22). This slough is an underfit 

channel in abandoned main stem flow paths and, away from 

the main stem-dependent entrances, has adjusted its channel 

location only within the confines of the former main stem 

banks since 1948.

Taiya River active main stem channel change since 1948 

has been largely accomplished through bank erosion. Some 

evidence indicates bank erosion processes are seasonally and 

perhaps episodically linked to high flows. Biweekly NPS bank 

monitoring begun in early summer 2017 noted minimal erosion until late summer or early autumn, when daily discharges 

were highest (Richards and others, 2017). Inglis and Pranger 

(2002) implicate a large flood reportedly from the 1920s and 

the large 1967 flood with periods of substantial erosion, but 

adequate evidence to verify or refute the 1920s flood and 

channel change associated with these dates was not found in 

this study. Bank height and materials play an important role in 

facilitating or resisting bank erosion. Bedrock banks locally 

constrain the channel but the low, unconsolidated sand and 

gravel banks throughout most of the mapping area offer little 

erosion protection. Taller banks flanking the eroding meander in the Dyea area (VK 2.0) intersect the river well below 

the protective root zone of the overlying forest (fig. 18C), 

also providing little erosion protection. Accumulations of 

large woody debris can affect channel locations at an annual 

to decadal scale. Log jams have anchored bars and slough 

entrances within the mapping area. However, other accumulations, such as the large accumulations of large woody debris 

photographed by Inglis and Pranger (2002) lining the right 

bank in the Dyea area that were partly washed out by 2017, 

have been more ephemeral.

Development since the 1940s introduced engineered 

channel controls. Bank protection lines much of West Creek 

but only selected areas of the Taiya River. At the Taiya River 

bridge, short stretches of riprap on both banks protect this 

relatively stable channel, the location of which is enforced 

along the upstream left bank by bedrock banks that merge 

with the 1952 dike across the former slough east of Dyea 

Road. Although the dike and bank reinforcement had lingering effects limiting channel migration potential, consolidation 

of flow to one channel here was likely already in progress by 

1948. Riprap lines the right bank at the private property at VK 

3.5, and several discrete engineered collections of large woody 

debris deflect flow upstream of the property. Dyea Road is 

protected by riprap at an eroding bank adjacent to the southern 

tip of the NPS campground (fig. 18D). In the 1970s, the U.S. 

Army Corps of Engineers and USGS developed plans for bank 

protection in the Dyea area, but NPS opted for a less costly 

and invasive approach of relocating cultural and historical 

artifacts (Inglis and Pranger, 2002).

Vertical channel change assessed from 1969–2019 stage 

at the USGS Taiya River streamgage shows apparent incision since 1969. Historically measured stages from 1969 and 

the 1970s streamgaging period are elevated above the stage 

estimated from the most recent (2016) rating curve for a range 

of discharges, as are many of the measured stages from the 

2002 to 2019 streamgaging period (fig. 23A). Over the period 

of record, the historical–recent stage differences (residuals) 

for the subsetted discharge measurements show a downward 

trend (fig. 23B), even when considering only the most recent 

of the two streamgaging periods. A linear regression with 

an adjusted coefficient of determination (R2) of 0.88 fitted 

through the stage differences shows an average bed lowering 

of about 7 mm/yr at the streamgage over 50 years (1969–2019; 

fig. 23B). Factors not addressed by this analysis include 

the large gap between periods of data, the apparent elevated 

incision indicated for the most recent few years, the location 

of the streamgage at a relatively laterally stable location that 

might be more prone to incision as an adjustment mechanism, 

and the lack of any abrupt changes in the longitudinal profile 

(fig. 16). Additional analysis to conclusively quantify incision would need to examine these issues and seek to quantify 

downstream horizontal migration of river base level.

Sediment Sources

The availability of sediment in an actively deglaciating 

basin can be qualitatively evaluated from the extent and accessibility of sediment exposed during retreat. Within the Taiya 

River Basin, the largest easily entrainable sediment sources 

consist of moraines and landslide debris in the West Creek and 

Nourse River valleys. Much of the sediment in these valleys is 

captured in lakes or stored in moraines or fans not in contact 

with the main stem and not accessible to the stream under 

2019 conditions, but dynamic glacier, lake, and stream conditions could increase availability. Suspended sediment is fine 

grained and easily transported throughout the river system, 

such that the largest sediment sources for the turbid water 

in the mapping area are almost certainly the glaciers in the 

headwaters of the three Taiya River tributary valleys. Bedload 

sediment is coarser and more susceptible to deposition in lakes 

or within the channel where slopes and corresponding stream 

power decline.
Geomorphology 39

Slough

CHILKOOT TRAIL

CHILKOOT TRAIL

CHILKOOT TRAIL

CHILKOOT TRAIL

A

B

C

Main stem 2003

main stem path

Abandoned 

main stem path

Abandoned 

Beaver 

ponds

Tributary

fan

Tributary

fan

Mapping

 area

Flow

A

B

C

A

B

C

A

B

C

A

B

C

A

B

C

A

B

C

7.0

6.0

7.0

6.5

6.5

6.0

6.5

6.0

6.0

6.5

7.5 7.5

7.5

7.5

7.0 7.0

EXPLANATION

Elevation, in 

meters 

25.0

14.0

Valley kilometer

Location of 

interest

4.5

Mapping area 

boundary

A

2003 slough

135°21' 135°20' 135°21' 135°20'

59°

33'

59°

32'

30"

59°

33'

59°

32'

30" 0 0.2 0.4 0.6 KILOMETERS

0 0.1 0.2 0.3 MILES

Beaver 

ponds

Imagery from USGS aerial photograph georeferenced by National Park Service, 1948 photography. Imagery: 

National Park Service orthophotograph, 2003 photography; Esri World Imagery map service, 2014 photography, 

copyright 2018 Esri and its licensors; National Park Service digital elevation model, 2003 data. Projection: Universal 

Transverse Mercator Zone 8N, North American Datum 1983.

Chilkoot 

Trail

D. 2014

A. 2003

C. 2003

B. 1948

Figure 22. Changes to slough entrance conditions and constraints on slough flow path at valley kilometers (VK) 6.0–7.5, Taiya River, 

Alaska. A, Lidar elevation data for 2003 are shaded in 0.5-meter bands showing the upper part of the slough, which extends from VK 

4.5 to 7.5, and a tributary stream through a series of beaver ponds (see ground photo in fig. 18F) confined within the wide flow path of a 

suite of former main stem channels abandoned between 1894 and 1948. B and C, The 1948 slough entrance upstream of location A and 

the part of the slough flowing through location B became inactive by 2003. C and D, Main stem migration near locations A and B and 

creation of a log jam near location A between 2003 and 2014 (completed by 2010) likely affected the amount of flow entering the slough. 

Increased flow damaged abutments for a Chilkoot Trail footbridge at location C. Main stem activated between 2003 and 2018 is mapped 

in figure 17.
40 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

tac19-5267_fig23

N = 63

Adjusted R2 = 0.88

Slope = -0.007 m/yr

2016 

rating curve

Historical 

measured

stages

−0.1

0

0.1

0.2

0.3

0.4

1960 1980 2000 2020

Date

Stage residual, in meters

3.0

4.0

5.0

6.0

1 10 100 1,000

Discharge, in cubic meters per second

Stage, in meters

B. Taiya River (USGS streamgage 15056210)

A. Taiya River (USGS streamgage 15056210)

1970

1980

1990

2000

2010

Date

EXPLANATION

Figure 23. Incision inferred from changes in stage for a given 

discharge at U.S. Geological Survey streamgage at Taiya River,

(15056210), Alaska. A, Selected subset of historical measured 

stage, by date, during 1969–2019 and the most recent rating curve, 

dated 2016. B, Regression line fitted to the differences (residuals) 

between the historical (measured) and recent (estimated from 

the rating curve) stages for a given discharge during 1969–2019. 

Positive differences indicate that the measured stage was higher 

than the stage estimated from the 2016 rating curve. [m/yr, meters 

per year]

In the West Creek basin, large lateral moraines from glaciers in the headwaters present a substantial sediment source 

that at present is largely captured in a pro-glacial lake (figs. 1

and 10A). Visible as a small feature in 1948 aerial photographs, when the glacier now contained in the eastern drainage 

extended into the valley bottom, this lake grew as the glacier 

retreated then partially filled during the 2002 lateral moraine 

failure and glacial lake outburst flood (fig. 10A, B, and C). In 

the western drainage, the partially failed valley bottom and 

large lateral moraines constitute an additional likely sediment 

source as the stream continues to adjust to the new slope of 

the failure, also at present captured in the lake. If the lake 

fills, sediment from the eastern and western drainages would 

directly enter West Creek, and the initiation of channel migration could harvest additional sediment from lateral moraines. 

Mass movements and tributaries along the West Creek valley 

walls also present a long-term sediment source. Landslide 

deposits adjacent to or encompassing the stream are visible in 

aerial photographs dating back to 1948. Alluvial fan deposits 

from small streams are common, supplying sediment not fully 

carried away by West Creek and resulting in the development 

of small fans that have pushed the stream away from the valley wall in some locations.

Processes associated with glacier retreat in the Nourse 

River valley have exposed, trapped, and episodically released 

sediment. Although as of the date of 2014 aerial photography, 

combined drainage from two large tributary glaciers directly 

entered the Nourse River 7 km upstream of the main stem 

Taiya River valley bottom, a pro-glacial lake immediately 

upstream trapped sediment from upvalley. As of 2014, two 

additional pro-glacial lakes in the valley bottom 14 km and 

15 km from the main stem Taiya River valley bottom trapped 

sediment from a tributary glacier and the main valley glacier, respectively. Although the valley bottom lakes presently 

restrict the sediment supply from more than 13 km of the 

valley through mountainous, glacierized terrain in the upper 

Nourse River basin, these sediment stores could gradually or 

episodically be released to the stream as lakes fill or burst. 

The integrity of moraines trapping proglacial lakes has been 

investigated somewhat inconclusively (Denton and others, 

2005, 2009), leaving open the possibility of a sudden pulse in 

sediment supply from glacial lake outburst flooding. Less catastrophic sediment harvest in the lower 7 km of Nourse River 

includes stream erosion of small tributary fans.
Geomorphology 41

Off-Main-Stem Channels

Off-main-stem channels are important contributors to 

the complexity of the habitat mosaic in the Taiya River valley 

bottom, even after abandonment by the surface-water source 

that formed them. Many of the channels mapped for this study 

are commonly referred to as off-channel habitats, or areas not 

subject to the full flow of a main stem channel. Because this 

study specifically inventoried channels present in the 2003 

elevation data regardless of 2003–18 flow conditions, the term 

off-main-stem channel is used instead. This study identified 

29 major off-main-stem channels or channel networks in the 

mapping area (fig. 24). Results of the channel attribute inventory are presented in table 6 in two categories: (1) channels 

associated with the Taiya River abandoned surfaces or small 

tributary fans and (2) channels associated with the West Creek 

fan. Photographs of selected examples of off-main-stem channels in the mapping area are shown in figure 25. In addition to 

the inventoried channels, the complex of channels and beaver 

ponds in an abandoned main stem path near VK 6.5 (figs. 22

and 24) did not include channels readily mappable with the 

study methods but is considered in this discussion. An additional wetland habitat not associated with a mappable channel 

is present adjacent to the western valley wall at VK 2.5.

Off-main-stem channels were dominantly main stem in 

origin (table 6), although several were subsequently modified 

by tributary flow. Within the mapping area, the two largest tributaries (other than West Creek, considered a main 

stem channel for the purposes of this inventory) are Nelson 

Creek (figs. 1 and 3) and an unnamed tributary, which formed 

channels across their fans (channel identifiers T20 and T05, 

respectively; fig. 24) but flowed no more than 200 m across 

the valley bottom before emptying into larger channels of 

main stem origin. At several smaller tributaries, tributary 

flow in abandoned main stem channels (for example, channel 

T04, fig. 24) has resulted in a smaller channel form within an 

enforced flow path (an underfit stream). In other cases, such 

as at channel T16 (fig. 24), small tributaries have not substantially modified abandoned main stem channel forms but 

contribute to wetlands, ponded areas, or small flowing streams 

or disappear underground.

On the West Creek fan, off-main-stem channels nearly 

entirely consisted of small networks of channels having 

short-radius bends and uneven margins, unlike the smooth, 

long-radius bends associated with Taiya River channels, and 

were not associated with any obvious water sources active in 

2017–18 (figs. 6D and 15). Their general radial orientation 

and planform dissimilarity to main stem channels indicate an 

origin more associated with former West Creek fan processes 

than main stem processes. The presence of well-established 

grasses and shrubs but lack of trees (fig. 25D), the interconnected nature of the channels, and the truncation of some 

channels by Dyea Road indicate that the channels did not 

form under conditions over the past several decades but could 

have been active within the past 100 years. Origins for these 

apparently relict features could include smaller fan channels, 

groundwater sapping, or other processes not determined as 

part of this reconnaissance project.

Within the inventoried channels, water was present at 62 

percent of the off-main-stem channels and ranged from small 

ponds to flowing streams. Groundwater fed 55 percent of the 

channels, tributaries contributed to 27 percent of the channels, 

and high flow or backwater from the main stem entered 17 

percent (multiple sources are possible such that these do not 

sum to 100 percent). Some channels (such as channel T12) had 

multiple sources, conveying clear water for parts of the year 

and receiving turbid Taiya River flow at higher discharges. 

For most channels near Taiya Inlet, the channel water surface 

equals the 2007–2011 mean higher high-tide elevation (5.1 m) 

at about VK2.0, which has allowed salt water to intrude into 

the distal reaches of Nelson Slough (channel T18) and create 

brackish environments observed at least as far upstream as VK 

1.0.

Beaver dams have effectively regulated hydrologic conditions in selected off-main-stem channels, creating ponds that 

have persisted over decades and locally altered valley bottom 

vegetation. Beaver activity is present upstream and downstream of West Creek but has most prominently affected two 

areas upstream of West Creek. At channel T04, a complex of 

flooded forest areas and former roads and trails fed by a tributary at VK 5.5 and dammed by beavers extended about 1 km 

along the channel as of 2018. The second area, an extensive 

series of beaver ponds and small streams along the Chilkoot 

Trail near VK 6.5 (fig. 22), was present before 2003 and 

extended about 600 m along the valley by 2018. Standing trees 

killed by inundation (fig. 18F) and stressed pond-marginal 

vegetation indicate hydrologic conditions here are still in flux.

Clearwater side channels, considered here to be wetted 

channels open to the main stem at their exit but not at their 

head and fed by tributaries or groundwater, are identified here 

because of their potential importance as fish habitat. Twelve 

mapped off-main-stem channels met this description, of which 

channels T18 (fig. 25A), T12, T02 (fig. 25E), T20 and T05 

were noted to be actively flowing (table 6). Several of these 

five channels are known anadromous fish streams and were 

occupied by spawning salmon during field studies (particularly 

Nelson Slough/Nelson Creek and channel T04).
42 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

tac19-5267_fig24

West Cr

Taiya River Taiya

Inlet

Area of

complex

channels

DY03

WC02

WC04

DY19

TR01

DY33

DY13

DY14

T20

T19

T17 T16

T14

T15

W08

W09

T18

W07

W06

W05

W03

W04

T09

W02

W01

T06

T12

T05

T03

T04

T02

T01

T07

T11

T08

T13

T10

5.5

6

7

0

5

4.5

4

3

2

1

6.5

3.5

1.5

2.5

0.5

7.5 EXPLANATION

Off-main-stem channel and identifier

6.5 Valley kilometer

DY13 National Park Service amphibian monitoring site and identifier

Boundary of Klondike Gold Rush National Historical Park

T18

Mapping area boundary

135°22' 21' 135°20'

59°

33'

32'

31'

59°

30'

Imagery from National Park Service orthophotograph, 1 ft pixels, 2003 photography. 

Universal Transverse Mercator Zone 8N, North American Datum 1983.

0 0.5 1 1.5 KILOMETERS

0 0.2 0.4 0.6 MILES

Figure 24. Off-main-stem channels in the lower 7.5 kilometers of the Taiya River valley bottom, Alaska, and amphibian monitoring 

sites maintained by the National Park Service.
Geomorphology 43

Table 6. Attributes of off-main-stem channels in the lower 7.5 kilometers of the Taiya River valley bottom, Alaska. [Site locations are shown by channel ID (arbitrary field identifier) in figure 24. Attributes are defined by short name in table 4. Abbreviations: ID, identifier; WY, water year; m3/s, cubic meters per second]

Channel ID 

(CHAN_ID)

Conditions at upstream end 

(head)

Conditions at 

downstream 

end (exit)

Water 

sources 

(wtr_source)

Surface-water 

receiving body 

(sw_sink)

Observation 

date and source 

(obs_date)

Water 

presence 

(water_pres)

Streamflow 

conditions 

(flow)

Date of 

abandonment 

by main stem 

(abandoned)

Channelforming 

processes 

(form_proc)

Infrastructure present 

(culvert)

Comments 

(comments)

Channels associated with Taiya River abandoned surfaces or small tributary fans

T01 unknown flowing groundwater main stem March 9, 2017 orthophotograph present unknown prior to 1948 main stem no roadT02 inaccessible flowing groundwater main stem June 19, 2018 field 

observations

present flowing prior to 1948 main stem no road

T03 unknown unknown groundwater main stem March 9, 2017 orthophotograph present unknown prior to 1948 main stem no roadT04 flowing flowing groundwater, 

tributary

main stem June 19, 2018 field 

observations

present flowing prior to 1948 main stem, 

tributary

culvert

T05 flowing flowing tributary main stem June 17, 2018 field 

observations

present flowing n/a main stem, 

tributary

no road

T06 unknown unknown unknown none not visited, not 

visible in aerial photographs

unknown unknown prior to 1948 main stem no road

T07 inaccessible flowing groundwater, 

main stem backwater

main stem June 19, 2018 field 

observations

present limited flow prior to 1948 main stem no road

T08 inaccessible flowing groundwater off-main-stem 

channel

June 17, 2018 field 

observations

present limited flow prior to 1948 main stem, 

tributary

footbridge

T09 inaccessible unknown unknown main stem June 18, 2018 field 

observations

absent none after 1948 main stem no culvert

T10 inaccessible inaccessible unknown none not visited, not 

visible in aerial photographs

unknown unknown prior to 1948 main stem no road

T11 unknown flowing groundwater, 

possible tributary

off-main-stem 

channel

June 17, 2018; 

June 19, 2018 field observations

present limited flow prior to 1948 main stem, 

tributary

footbridge

T12 flowing flowing groundwater, 

main stem, tributary

main stem June 17, 2018; 

June 19, 2018 field observations

present flowing prior to 1948 main stem footbridge

T13 inaccessible flowing groundwater, 

main stem backwater

main stem September 1, 2017 

field observations

present limited flow after 1948 main stem no road

T14 inaccessible not blocked groundwater main stem June 18, 2018 field 

observations

evidence of 

ephemeral presence

none after 1948 unknown no road
44 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska Table 6. Attributes of off-main-stem channels in the lower 7.5 kilometers of the Taiya River valley bottom, Alaska.—Continued Channel ID (CHAN_ID) Condi- tions at up- stream end (head) Conditions at downstream end (exit) Water sources (wtr_source) Surface-water receiving body (sw_sink) Observation date and source (obs_date) Water presence (water_pres) Streamflow conditions (flow) Date of abandonment by main stem (abandoned) Channel- forming processes (form_proc) Infrastruc- ture present (culvert) Comments (comments) T15 evidence of flow not blocked groundwater, main stem main stem August 30, 2017 field observa- tions present ponded prior to 1948 main stem culvert T16 inaccessible flowing groundwater, tributary main stem June 16, 2018 field observations present ponded to lim- ited flow after 1948 main stem culvert T17 evidence of flow flowing groundwater, main stem main stem August 31, 2017 field observa- tions present ponded to lim- ited flow after 1948 main stem no road T18 inaccessible flowing groundwater, tributary ocean August 29, 2017; June 18, 2018 field observa- tions present ponded to flowing prior to 1948 main stem, tributary culvert Nelson Slough T19 inaccessible inaccessible groundwater, tributary none August 29, 2017; June 16, 2018 field observa- tions present ponded to flowing after 1948 main stem no culvert T20 flowing flowing tributary off-main-stem channel August 29, 2017 field observa- tions present flowing n/a tributary no road Nelson Creek Channels associated with the West Creek fan W01 inaccessible inaccessible none none June 19, 2018 field observations absent none prior to 1948 unknown no culvert W02 inaccessible inaccessible groundwater none June 19, 2018 field observations present ponded prior to 1948 unknown no culvert W03 inaccessible inaccessible unknown none not visited, not visible in aerial photographs unknown unknown unknown unknown no road W04 inaccessible inaccessible unknown none not visited, not visible in aerial photographs unknown unknown unknown unknown no road W05 not blocked not blocked main stem none June 17, 2018 field observations absent none after 1948 main stem unknown W06 inaccessible inaccessible unknown none not visited, not 

visible in aerial photographs

unknown unknown unknown unknown no road

W07 inaccessible inaccessible none none June 17, 2018 field 

observations

absent none unknown unknown unknown

W08 inaccessible inaccessible none none June 18, 2018 field 

observations

absent none unknown unknown no culvert

W09 unknown unknown possible tributary none not visited, not visible in aerial 

photographs

unknown unknown unknown unknown no road
Geomorphology 45

tac19-5267_fig25

A

C

B

D

E F

Figure 25. Photographs of examples of off-main-stem channels in the Taiya River valley bottom, Alaska. A, View 

upstream, post-spawning salmon carcasses in the tidally affected Nelson Slough (T18) immediately upstream of the 

confluence with Nelson Creek, valley kilometer (VK) 1.0, August 29, 2017. B, View downstream, wetlands in Nelson 

Slough (T18) at road bridge, VK 1.2, June 18, 2018. C, View downstream, shallow water in wetlands in channel T17, 

VK1.8, August 31, 2017. D, View upstream, author standing in center of channel W07, VK 3.3, no water present, June 17, 

2018. E, View downstream, clearwater side channel in channel T02, VK 5.8, June 19, 2018. F, View upstream, Jami Belt 

of the National Park Service observing clearwater side channel in channel T11 upstream of Chilkoot Trail footbridge, 

VK 4.0, June 17, 2018. Photographs A–C and E–F taken by Janet H. Curran, U.S. Geological Survey; photograph D taken 

by Jami Belt, National Park Service.
46 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

Selected Hydrogeomorphically 

Dependent Resources

River Recreation

The reach of the Taiya River from a few hundred meters 

upstream of the West Creek confluence to the mouth of the 

Taiya River is road accessible and has no notable rapids. This 

reach is valued as a gentle float for non-motorized watercraft 

(fig. 18B). Abundant large woody debris in the form of relatively mobile downed trees temporarily stranded in mid-channel (fig. 26) and more persistent, partly eroded trees leaning 

into the river from the bank pose a riverine hazard. Hydraulics at selected river bends create challenges surmountable 

or avoidable by most craft at all but the highest flows. River 

guides suspend operation for safety reasons at a gage height of 

5.2 m, or 201 m3/s. Daily discharge and annual peak discharge 

records, respectively, show that flows of this magnitude occur 

for a full day in some years but are equaled or exceeded for 

part of a day nearly every year. At very low flows, the river 

cannot float loaded rafts in selected areas such as VK 1.5–2.0, 

and rafters must portage over shallow reaches. Taiya River 

streamflow is consistently high in summer, but early spring 

low flows are common. Commercial rafting operators prefer 

to begin as soon as adequate flow is available and are thus particularly sensitive to the timing and magnitude of rising spring 

flows, about mid-April to mid-May.

Boreal Toad Habitat

The Anaxryus boreas boreas (boreal toad), a subspecies of the Anaxryus boreas, formerly Bufo boreas (western 

toad), is identified as a species of greatest conservation need in 

Alaska (Alaska Department of Fish and Game, 2015) and was 

considered for listing as endangered in other western states 

(U.S. Fish and Wildlife Service, 2017) owing to widespread 

population decline. The Alaska Wildlife Action Plan (Alaska 

Department of Fish and Game, 2015) categorizes the western 

toad as a sentinel species indicative of ecosystem health or 

environmental change and as culturally important. Although 

Alaska toad habitat preferences are less well known, toad 

breeding sites in other western states occupy wetland habitats 

ranging from open water to wet meadows, usually at elevations greater than 2,000 m (U.S. Fish and Wildlife Service, 

2017). Following the first detection of a breeding site for the 

boreal toad within KLGO in 2002, a 2005 KLGO presence/

absence study documented breeding sites, and subsequent 

monitoring focused on observations at core monitoring sites 

where breeding had been detected (fig. 3) (Surdyk and Waldo, 

2018). In 2017, the monitoring program documented evidence 

of breeding at 4 of the 8 core monitoring sites in KLGO, all in 

the West Creek or main stem Taiya River valleys (Surdyk and 

Waldo, 2018).

Boreal toads in KLGO (fig. 27) are known to use lowelevation wetlands as breeding sites. Six of the core KLGO 

monitoring sites are within the mapping area, all downstream 

of West Creek. An overlay of the monitoring sites with the offmain-stem channels mapped for this study (fig. 24) indicates 

that 5 of the 6 sites occur in channels abandoned by the main 

stem Taiya River since the 1940s (or slightly earlier in the case 

of Nelson Slough). One site, KLGO monitoring site DY19, 

occurs in a wetland not associated with a channel and might 

be fed by a small tributary entering from the valley wall. Two 

of the abandoned channel sites were subsequently modified 

by human activities, DY03 by gravel extraction activities that 

created ponds and DY33 by earthmoving activities associated 

with road construction staging and parking. Although several 

sites contain ponded water, and several appear to ephemerally 

support a small amount of streamflow, particularly at their 

downstream ends, none of the channels supported spatially or 

temporally continuous flowing water. Inundation by saltwater (in Nelson Slough) or by main stem water (at monitoring 

site TR01; fig. 24) episodically modifies flow conditions or 

water levels. Considering that the channels containing the toad 

breeding sites form a topographic low, and that no consistent 

surface-water source can be identified, shallow groundwater 

forms the most likely water source for the wetlands supporting 

the toad breeding sites.

Sites Near Eroding Banks

Many KLGO visitor amenities, including a campground 

and the Chilkoot Trail trailhead, and historical or archeological 

structures and artifacts important to NPS, such as the historic 

Dyea townsite, are situated near active or inactive river banks. 

In addition, public roadways and private properties border the 

Taiya River in some locations (fig. 3). The present stability 

of river banks is important to the security of existing features 

on these public and private properties, and the future stability 

of river banks is an important consideration in the planning 

process for siting future facilities, including NPS trail, road, 

and parking infrastructure.

Bank erosion has affected private and public properties 

and historical artifacts along the developed part of the Taiya 

River valley bottom since the early 1900s. Although channel 

migration rates since about the mid-1990s are small relative 

to those from 1948 until about the mid-1990s, bank erosion in 

the recent period has threatened structures and resulted in the 

loss of historical artifacts. Notable areas of bank erosion since 

the 1990s include a reach at VK 3.5 (fig. 17) and the sweeping 

meander bend near the Dyea townsite/NPS campground at VK 

2.0 (figs.17 and 20).
Selected Hydrogeomorphically Dependent Resources 47

tac19-5267_fig26

Figure 26. Large woody debris in mid-channel, Taiya 

River, Alaska. Photograph taken by Janet Curran, U.S. 

Geological Survey, August 30, 2017.

A B

Figure 27. A, A boreal toad adult and, B, Metamorphs in wetlands formed in abandoned sloughs of the Taiya River, Alaska. 

Photographs by Janet Curran, U.S. Geological Survey, A, June 16, 2018, and B, August 29, 2017.
48 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

At VK 3.5 (fig. 3 and just south of the area shown in fig. 

21), channel change in the 1990s eroded the right bank (as 

viewed by an observer looking downstream) along the only 

developed bankside private property on the river and motivated the placement of riprap to protect the bank and large 

woody debris to redirect streamflow by the 2000s. Channel 

change at this location has involved complex reworking since 

at least 1948 that is likely associated with the natural reconfiguration of the West Creek confluence. Several episodes of 

meander migration immediately upstream (fig. 21, location B) 

resulted in reverse curvature of the 1948 meander and development of a new meander with an apex at VK 3.5. Erosion 

during 2017–18 continued to affect the left bank, as detected 

as by NPS monitoring (Richards and others, 2017) and seen in 

aerial imagery (table 2), and unprotected areas near the private 

property on the right bank.

River bank erosion associated with meander migration 

near the Dyea townsite (fig. 20) has drawn repeated attention for its incursion on this historic area, which originally 

contained many Gold Rush artifacts and at least two historical 

cemeteries. As of 2018, more than one-half of the townsite 

had been eroded away, including the recent loss of nearly all 

of the cemeteries. Two distinct areas of channel change can be 

identified at this site. At the downstream end of the historical 

Dyea townsite footprint, scalloped channel scars in the 1948 

aerial photograph (fig. 20) record channel migration prior to 

1948 that resulted in loss of the southeastern quadrant of the 

townsite and subsequent abandonment of the area, now part 

of a low terrace (mapped as abandoned channel in fig. 17). 

A second area consisting of the existing meander centered at 

about VK 2.0 and extending from VK 1.7-2.6 has eroded episodically since about the 1920s. The ongoing progression of 

this meander from part of a relatively straight suite of channels 

along the eastern side of the valley in 1917 to a pronounced 

meander bend can be seen in ground and aerial photographs 

and historical property survey maps and has been detailed by 

annual NPS monitoring since 1979 except for a brief period 

in the 1980s (Inglis and Pranger, 2002; Richards and others, 

2017). A maximum of 150 m of erosion occurred between 

1918 and 1948, followed by a roughly equivalent amount of 

erosion between 1948 and 2018. The current right bankline 

(looking downstream) is the cumulative product of lateral 

migration of an upstream meander active between 1948 and 

1970 and a partly overlapping, slightly downstream meander active between 1970 and 1979, followed by downstream 

migration of the combined meander between 1979 and 1992. 

Between 1992 and 2016, erosion was minor to negligible. In 

May 2017, monitoring detected a new episode of erosion, and 

during 2017 as much as 14 m of erosion widened the curve 

near the apex of the meander (Richards and others, 2017). This 

brought the maximum lateral erosion between 2003 and 2018 

to 19 m (seen as the recently added main stem area in fig. 17). 

Along the inside of the meander bend, former channel areas 

progressively became a point bar, which in 2019 supported 

NPS facilities, including a campground, and erosion has 

affected the campground and Dyea Road (fig. 18D).

Hydrogeomorphic Implications for 

Taiya River Resources

The geologic and fluvial history of a river valley provides 

a basis for anticipating future river conditions consistent with 

the context of natural processes in the basin. For the Taiya 

River, it is important to consider how natural processes—

faulting, glacier retreat, isostatic rebound, flooding, changes 

in water and sediment supply—have conditioned the valley 

bottom and how dynamic those processes are. The general 

configuration of the main stem valley has been set by the geologic-scale processes of faulting and the long-term erosive and 

depositional power of glaciers and streams. The geomorphic 

history of the valley can be considered to have established the 

framework for channel position and planform, and the present 

streamflow and sediment regimes, together with large woody 

debris and beaver activity, can be considered responsible for 

maintaining or modifying the stream channel morphology and 

availability of water for aquatic habitats and wetlands in the 

future.

Evolution of Valley Bottom Surfaces and 

Channels

Informed management and conservation of the KLGO 

resources considered in this study rely on understanding the 

primary hydrogeomorphic controls on channel form, channel 

position, and channel formation. The Taiya River consolidated 

its channel from multiple major paths in 1894 to a single 

major path by 1948. Since 1948, the river has narrowed its 

suite of active channels and bars within this flow path. Unlike 

the frequent reworking of braided channels in many glacial 

streams, the general path of the mostly single-thread Taiya 

River has not changed appreciably since 1948. The notable 

narrowing and stabilizing of the Taiya River from a multithread, braided planform to a mostly single-thread planform 

could not be readily attributed to one factor for this reconnaissance study. The river changes since prior to the Gold Rush 

that are recorded in abandoned channels (fig. 14) and in aerial 

photography occur concurrently with dynamic changes in 

glacier contributions to streamflow and sediment, including 

known and likely glacial lake outburst floods that could have 

temporarily widened the unvegetated corridor, particularly 

if recurring, but also including the loss of direct sediment 

contributions by the formation of proglacial lakes. Regardless 

of cause, the importance of an apparent progressive change in 

the width of the active main stem is that, at the valley scale, 

it indicates some permanence to the current general flow path 

and a reduction in the capacity of the stream to readily rework 

the entire valley bottom. At the multi-kilometer scale within 

the mapping area, the general location of the Taiya River is 

presently relatively laterally stable and could remain relatively 

stable at this scale unless future flow and sediment regimes 

change.
Hydrogeomorphic Implications for Taiya River Resources 49

Within the mapping area, notable channel change 

occurred at small spatial and temporal scales, on the order 

of decades over reaches on the order of 1 km long. From the 

West Creek confluence to about 1 km downstream, the West 

Creek and Taiya River channels have changed in a complex 

manner since 1894 (figs. 21 and 24). Continued minor change 

between 2003 and 2018 indicates that bank erosion and channel change will continue at this location until a more stable 

configuration is reached. Downstream of the Taiya River 

bridge, the branching river of the Gold Rush era consolidated 

into a single strongly meandering channel along the eastern 

side of the valley by 1948, a change not unlike the reduction of flow paths upstream of West Creek. Complex meander migration since the late 1800s that cumulatively eroded 

one-half of the former Dyea townsite occurred episodically, 

such that periods of relative stability (on the order of decades) 

were interspersed with relatively swift channel migration (on 

the order of single to multiple years). The assertion by Inglis 

and Pranger (2002) that “the river will eventually migrate 

through and destroy the remaining portions of Dyea if the 

channel bank is not stabilized” seems an accurate reflection 

on a river having an abundant supply of water and sediment in 

an easily erodible, fluvially reworked valley bottom, although 

the timing of this eventuality is unknown. The size of the 

present single large meander bend at VK 2.0 (figs. 2 and 20), 

technically a composite of several former smaller bends, is 

unprecedented within the mapping area. Short-term erosion of 

the outer bank of this bend, on the scale of that seen in 2017 

or even the larger amounts of several decades ago, is likely to 

continue until more substantial and complex channel changes 

reduce meander curvature and rework flow paths.

Influences on Taiya River position and channel migration since 1894 include flooding, uplift, West Creek processes 

and deposits, and locally, large woody debris. Large floods, 

whether meteorologic or outburst, have the potential to 

reset vegetation cycles, alter aquatic habitat characteristics, 

erode banks, rework channel locations, and flush or deposit 

sediment. The effect of flooding prior to 1948 is difficult to 

ascertain but was suggested by Inglis and Pranger (2002) to 

have initiated bank erosion in the Dyea area. The largest flood 

in the Taiya River since 1948, a 1967 rainfall-generated flood, 

damaged infrastructure (Boning, 1972), but the extent of major 

channel change that can be attributed to the flood is unknown. 

The 2002 West Creek glacial lake outburst flood appears to 

have widened the active stream corridor in West Creek and 

flooded, but not substantially altered, the West Creek fan 

and the Taiya River. However, bank erosion noted during 

2017–18 occurred in the absence of large floods. Although 

large floods have affected Taiya River channels, change has 

not been exclusively associated with large floods, indicating 

that the range of flows in the past several decades are capable 

of modifying channel planform despite apparent reductions in channel size since 1894. Flooding also can form or 

mobilize collections of large woody debris, or log jams. Log 

jams present at the entrances to many back-bar channels and 

sloughs often regulate flow to these small channels, and buried 

relict log jams may locally control channel migration (Inglis 

and Pranger, 2002). Large woody debris was common as of 

2018 and includes entire mature trees, indicating that channel 

migration is capable of harvesting trees from relatively stable 

surfaces.

Land-surface uplift from isostatic rebound, when coupled 

with river incision, can create fluvial terraces and disrupt 

hydrologic connectivity of sloughs, off-main-stem channels, 

and groundwater systems supporting off-main-stem wetlands 

and channels. KLGO has recognized the potential for wetland 

drying associated with isostatic rebound (Bernatz and others, 

2011). Terraces consist of former fluvial surfaces elevated 

above the stream that can no longer be accessed by the stream, 

even at flood levels. Within the mapping area, terraces are 

most prominent along the right bank downstream of the West 

Creek fan, where bank heights commonly exceed 1 m (figs. 3

and 14). The currently perched head of Nelson Slough could 

be attributed to an uplift/incision response or to a bed elevation change from the complex channel changes there. Analysis 

of historical stages at the Taiya River streamgage shows an 

average of 7 mm/yr of incision there since the 1960s (fig. 23). 

Compared to uplift rates of 16 mm/yr, the 7-mm/yr incision 

indicates that uplift might be partly accommodated by stream 

incision and partly by downstream extension of base level 

as uplifted estuarine deltaic deposits become fluvial and that 

neither process dominates the fluvial response. Bedload transport in the Taiya River has been sufficient, at least in the past, 

to construct an extended gently sloping delta visible at low 

tide; as the delta is uplifted, the river becomes longer unless 

incision counteracts this effect. The Taiya River longitudinal 

profile was not critically examined for this study but the lack 

of obvious abrupt changes at the scale plotted in figure 16

indicates no substantial knickpoints have been generated by 

river adjustment to base-level change.

As a major tributary to the Taiya River, West Creek 

exerts a geomorphic effect on the Taiya River by substantially 

increasing the active width and sediment transport capacity 

of the river. Major main stem planform changes since 1948 

within the mapping area have all occurred downstream of 

West Creek, where additional streamflow from West Creek 

and from a major slough increases stream power. The historical West Creek fan contributes significantly to the downstream 

change in width of the historical Taiya River flood plain in 

the mapping area, which is a braid plain occupying the whole 

valley bottom from about 0.5 km upstream of West Creek and 

is a meander belt confined to about half the valley by the West 

Creek fan and fluvial or uplifted tidal terraces downstream 

(figs. 14 and 15).

The West Creek fan is inferred to have contributed to the 

century-scale persistence of the Taiya River location along the 

eastern side of the valley. The West Creek fan has deflected the 

Taiya River since at least 1894 (fig. 19A) and possibly longer 

despite the relatively inactive fan processes indicated by its 

surface features. The mostly non-wetted networks of small, 

short-radius channels clustered around the distal margins of 

the West Creek fan pre-date roads and cleared developments, 
50 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

providing a minimum age for changes to hydrologic processes 

on the West Creek fan. The interplay between West Creek fan 

construction and Taiya River fan trimming does not appear to 

be a geomorphically prominent process at the mouth of West 

Creek at the annual to decadal scale. Interactions at the West 

Creek confluence since 1948 instead appear more associated 

with channel migration. This indicates that the volume of 

bedload sediment from West Creek has been at least historically adequate to have affected the position of the Taiya River 

within the valley, but the sediment has not overwhelmed the 

transport capacity of the Taiya River since at least 1948. Taiya 

River channels are likely still sensitive to changes in the West 

Creek confluence angle, which is presently partly constrained 

by bank reinforcement.

Tributary fans often develop from deposition of coarse 

sediment at the slope transition between valleys because 

coarse sediment can no longer be carried by the lower-gradient 

stream, but the relative sediment size of the West Creek fan 

could not be determined from this study because of vegetation 

and lack of exposures except for sediment in the active stream. 

Bedload sediment presently transported across the West Creek 

fan does not appear substantially different from bedload sediment transported in the Taiya River. Sediment in bars at the 

mouth of West Creek is similar in size to sediment in Taiya 

River bars just upstream of West Creek. Boulders near the fan 

head indicate local coarseness, which could facilitate stream 

losses to groundwater.

In addition to the relative stability of the Taiya River 

stream corridor, channels within the corridor also shift 

infrequently. Unlike many glacier-fed streams in Alaska, 

where multiple channels interweave frequently across a broad 

gravelly plain, streams in the Taiya River Basin do not contain 

substantially braided reaches. This has implications for the 

disturbance regime of the river, which is stable relative to 

a braided river. Channel change since 1948 has occurred as 

slow, progressive change at most locations alternating with 

rapid, episodic change at selected meanders and infrequent, 

rapid complex channel avulsions in other locations.

Streamflow and Sediment Timing and 

Seasonality

KLGO resources dependent on the delivery of streamflow 

include river recreation and habitats for not only boreal toads 

but also important biological resources such as anadromous 

fish. The present effect of West Creek on the magnitude and 

timing of Taiya River discharge is also important as a basis for 

evaluating future proposals for West Creek water-resources 

management. The similarity of West Creek and Taiya River 

seasonal (fig. 9) and daily discharge patterns reflects similarity in basin characteristics and streamflow generating mechanisms between the streams. Notably, the West Creek basin 

contributes considerably to Taiya River discharge magnitude 

but produces only small variations in the timing of delivery of 

water, mostly as a slight shift toward more discharge in winter 

relative to the mean annual discharge (fig. 9). Thus, any future 

management of West Creek flow that reduces discharge magnitude but not timing would not necessarily alter the timing 

of Taiya River discharge. The decadal-scale shift toward an 

earlier spring rise in discharge seen between the two periods of gaging at the Taiya River streamgage (table 5, fig. 8) 

likely relates to an increase in spring temperatures, given the 

strong response of Taiya River discharge during April–June to 

temperature demonstrated for a short period of data available 

for the Taiya River streamgage (fig. 28). Drivers of change in 

spring temperatures can be the result of many factors beyond 

the scope of this study, including long-term trends in climate 

and decadal-scale oscillations such as the Pacific Decadal 

Oscillation.

Suspended sediment concentrations are an important 

consideration should future West Creek management include 

damming the stream and are presently relevant to considerations for riverine and seasonally inundated habitats. West 

Creek and Taiya River suspended sediment concentrations 

over the collective previous period of record (1963–2004) 

and the study period (2017–18) fell within the range of values 

measured in glacial streams, reaching the highest values in 

about June through September, concurrent with the peak of the 

summer high-flow season. Factors that could affect suspended 

sediment concentrations include possible moderating effects 

of small lakes in the Nourse River and West Creek valleys 

and temporary increases in suspended sediment supply from 

landslides in West Creek, although neither process was investigated for this study. The suspended sediment concentrations in 

West Creek and the Taiya River vary considerably with season 

and from year to year. As discrete samples, these measurements are more suited to seasonal characterization and miss 

other expected patterns, including diurnal variations, pulses, 

or variations between the rising and falling limbs of storm 

discharges. The turbidity measurements collected by SEAN 

(Sergeant and Johnson, 2018) provide additional temporal 

detail consistent with glacial streams, but additional calibration would be required to link the turbidity and suspended 

sediment data for quantitative assessment of continuous rather 

than discrete suspended sediment loads.

Wetland Water Sources

Wetlands, including off-main-stem channels, and sloughs 

are scarce in the mapping area but provide high-value habitat 

for species such as the boreal toad. In part because of this 

scarcity, understanding the processes that form wetlands and 

maintain their water levels is important. Estuarine wetlands 

are likely to remain at the interface between the Taiya River 

and Taiya Inlet, although their location will continue to 

migrate downvalley as land surface rises. Extensive, channelized flats exposed at low tide indicate that deltaic sediments 

extend offshore to support generation of new land with uplift. 

Off-main-stem wetlands in the mapping area are generally 

contained in former stream channels. Although new channels 
Hydrogeomorphic Implications for Taiya River Resources 51

tac19-5267_fig28

Mean monthly temperature, in degrees Celsius

0 3 6 9 12 15

Mean monthly discharge,

in cubic meters per second

0

50

100

150

April

May

June

EXPLANATION

Figure 28. Mean monthly discharge during April, May, and June, 

2012–16, in relation to mean monthly temperature for the Taiya 

River at U.S. Geological Survey streamgage 15056210, Alaska. 

Temperature data for the Taiya River are from the Western 

Regional Climate Center at https://raws.dri.edu/cgi-bin/rawMAIN.

pl?akATAI.

can be created in association with main stem channel changes, 

the present relative stability of the Taiya River indicates that 

rates of new off-main-stem channel creation are low. Relic 

channels on the West Creek fan may presently provide wetland 

habitat but appear unlikely to support flow under present 

2017–18 conditions. A wetland along the western valley wall 

at about VK 2.5 was the only wetland not clearly associated 

with a channel. Identification of wetland water sources is 

important for assessing the stability of wetlands in the face of 

local channel change, climate variability, and the unresolved 

potential for uplift to disconnecting wetlands from riverine 

flooding and groundwater sources.

Water sources observed or inferred for wetlands include 

small tributaries, which flow across abandoned fluvial surfaces before joining the main stem Taiya River or West Creek, 

seasonal or flood-related inundation by main stem flow, tidal 

effects, and groundwater discharge. By number of channels 

affected, the inventory of off-main-stem channels indicates 

that groundwater forms the primary water source for off-mainstem channels, followed by tributaries and then main stem 

flooding. The interpretation of flow in abandoned channels 

without an obvious surface-water source as groundwater-fed is 

supported by interpretations from Paustian and others (1994), 

who surmise that shallow flood-plain aquifers sustained flow 

in some abandoned main stem channels. The inventory of 

channels and water sources presented here serves to identify 

existing features but is a snapshot in time and can be expected 

to change as main stem channels move or water sources 

change.

In addition to precipitation and losses from the Taiya 

River, West Creek is a candidate for contributions to shallow valley groundwater recharge because of the steep nature 

of its entry to the valley and the potential coarseness of its 

fan deposits. Although flow losses from West Creek cannot 

be quantified with the available data, no gross discrepancies 

between West Creek and Taiya River streamflow or obvious 

springs were observed to indicate that West Creek is a strongly 

losing stream. Off-main-stem wetlands are present upstream 

and downstream of West Creek, also indicating no overt dominance of West Creek over groundwater recharge.

Monitoring Considerations

Existing monitoring efforts relevant to hydrologically 

or geomorphically dependent resources already underway 

at KLGO include monitoring of boreal toad breeding sites, 

which provides descriptive hydrologic observations such as 

pond drying and overtopping by main stem flow. KLGO also 

monitors bank erosion at selected locations. USGS monitors 

streamflow at the Taiya River streamgage, and SEAN monitors selected water-quality characteristics, including turbidity, 

at the streamgage.

Approaches to monitoring that further an understanding 

of the groundwater system that likely is the primary water 

source for many clearwater side channels and wetlands, 

including toad breeding sites, would facilitate the evaluation 

of the hydrologic effects of West Creek and the Taiya River 

on wetland habitats. This and other studies have attributed 

the presence of water in many small, non-tributary clearwater channels and other wetlands to groundwater (Paustian 

and others, 1994), but an understanding of the source of 

groundwater recharge would be required for evaluating future 

hydrologic conditions in these features. Because wetlands are 

not abundant in the Taiya River valley bottom and slowed 

lateral migration of the Taiya main stem indicates fewer 

off-main-stem channels are being created, wetlands have the 

potential to become individually important, such that localized 

processes might be relevant as well as valley-scale processes. 

Monitoring groundwater levels in wells or piezometers would 

more formally document conditions. The extent of seasonal 

and annual variations in groundwater levels would provide 

a basis for evaluating the relative effects of more regional 

groundwater sources and local aquifers that likely fluctuate 

in association with river levels. The spatial distribution of 

water-level monitoring could be designed to provide information on the influence of West Creek on the Taiya River valley 

bottom groundwater system. Other methods for determination 

of losses to groundwater include concurrent measurement of 

discharge upstream and downstream of potential loss points, 

such as on West Creek near the valley margin. Techniques for 

identification of water sources, such as isotopic fingerprinting, 

might also facilitate assessment of the relative contribution of 

West Creek.
52 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

Although the response of the Taiya River to rapid uplift 

is offset to some degree by lengthening of the stream downstream as estuarine, deltaic surfaces are uplifted, emergence 

of new land at the tidal interface and any incision that disconnects aquatic–terrestrial processes likely would also affect 

vegetation. Colonization of new land and shifts from water 

tolerant to water intolerant species can be a marker for hydrologic change. High-resolution imagery (aerial photographs or 

satellite imagery) analysis can assist with detection of vegetation changes, as can repeat field observations at plots. Detection of the river response to incision could include monitoring 

channel change at long-term fixed locations, such as the Taiya 

River bridge. Repeat longitudinal surveys of water-surface 

elevations, preferably at low flows or at a consistent flow, 

could provide a more spatially distributed measure of longterm elevation change.

The existing bank erosion monitoring program captured 

most of the major changes to banks downstream of West 

Creek since at least 2003, but this can be considered a period 

of relative stability in that most bank erosion consisted of 

progressive meander migration rather than complex reworking of channels. Periodic analysis of high-resolution imagery 

could complement this program by capturing changes at banks 

not regularly monitored and would assist with detection of 

complex channel changes. If major changes occur, new lidar 

acquisition can be an effective means to delineate eroded 

banks over a larger area and quantify analysis of changes in 

elevation.

Although this study provided a preliminary framework of 

the relative age structure of the valley bottom fluvial surfaces and coarse categories of formative processes for those 

surfaces, chronological dating (such as tree ring analysis or 

isotopic methods), stratigraphic assessment of deposits, and 

more detailed evaluation of the surface expression of fluvial 

deposits could help refine the understanding of the relative 

role of glacial lake outburst floods, the stability of the West 

Creek fan, and other geomorphic issues. A thorough investigation of aerial and ground imagery could also help determine 

the effects of major floods from outside the mapping area. 

A more formal measurement of bed-particle size than was 

possible for this study would be needed to conduct hydraulic 

analysis for engineering or environmental purposes or in support of analysis of river incision/deposition.

Summary and Conclusions

The Taiya River drains a 481 square-kilometer (km2) 

basin from glacierized mountains to Taiya Inlet at the head of 

Lynn Canal, a long fjord in southeastern Alaska. The upper 

part of the Taiya River and the Nourse River join near the 

head of a 14-kilometer- (km) long main stem valley, and West 

Creek, a major tributary, enters the Taiya River about 4.5 km 

from Taiya Inlet. Most of the main stem Taiya River valley 

bottom lies in the Chilkoot Trail Unit of Klondike Gold Rush 

National Historical Park (KLGO), founded in part to preserve 

and document culturally important artifacts and history from 

the 1897–98 Gold Rush and in part to foster understanding of 

the natural processes and species of this ecologically important corridor between coastal and interior Alaska. Recurrent 

proposals exploring the feasibility of a hydroelectric facility in the non-park headwaters of West Creek motivated this 

reconnaissance of the hydrology and geomorphology of the 

lower 7.5 km of the main stem Taiya River valley bottom and 

important hydrologically dependent resources of KLGO. The 

study conducted by the U.S. Geological Survey (USGS), in 

cooperation with the National Park Service, relied on a range 

of methods and data sources, including geomorphic mapping; 

review of historical surveys, aerial and ground photographs, 

and orthophotographs; lidar data; collection of suspendedsediment data; and published USGS streamflow and sediment 

data.

The Taiya River valley bottom owes its form to a suite 

of geologic processes, including faulting that set the general 

orientation of the valley, Pleistocene glacier occupation and 

retreat, and riverine processes that reworked the glacial outwash filling the valley bottom. Coastal influences include tidal 

estuarine processes and emergence of tidal surfaces uplifted 

by notably high rates of isostatic rebound from glacier retreat. 

Modern processes continuing to adjust the features of the valley bottom are a dynamic mix of fluvial processes, glacially 

controlled delivery of water and sediment, and uplift. As of 

2019, the Taiya River was mostly contained in a single main 

channel with mid-channel or lateral bars except where a few 

sloughs convey a small part of the flow. However, in the Gold 

Rush era, the river sustained multiple paths and long, large 

sloughs, including the prominent West Branch Taiya River, 

which is now the abandoned Nelson Slough.

Similar streamflow seasonality and daily variations are 

expressed in records from the USGS streamgages for West 

Creek and the Taiya River. The similarity in streamflow patterns can be attributed to the similarity in basin characteristics 

and streamflow generating mechanisms between the basins. 

Streamflow in both the Taiya River and West Creek is strongly 

controlled by the presence of glaciers over 29 percent of each 

basin, which contributes to a prolonged summer high-flow 

season from May to October that peaks in late July or August 

and a winter low-flow season from November to April. The 

correlation between daily means for the two streams for the 

common period of record, 1970–77, was relatively high (r = 

0.97) in the summer period and lower (r = 0.90) in the winter 

period. The two periods of USGS discharge record (1970–77 

and 2004–17) for the Taiya River provided an opportunistic comparison, although the relatively short, discontinuous 

record challenges interpretations. Mean annual discharge 

increased slightly in the more recent period, and changes in 

the seasonal distribution of flow include a shift toward an earlier spring freshet and an increase in spring and early summer 

flow magnitude associated with snowmelt in the more recent 

period. No floods larger than the meteorologically driven flood 

of 1967 have occurred within the USGS discharge record, 

but historical accounts indicate at least one comparably sized 

flood in the mapping area between the Gold Rush and the start 

of streamgaging.
Summary and Conclusions 53

Suspended sediment concentrations for six concurrent 

samples collected at USGS streamgages in water year 2017–

18 ranged from 13 to 162 milligrams per liter (mg/L) for West 

Creek and 6 to 284 mg/L for the Taiya River. The suspended 

sediment concentrations, relative to discharge, were slightly 

higher than historical values and consistent with seasonal 

and interannual variability common to glacial streams. The 

potential for future dynamic changes to the sediment supply 

of West Creek and the Nourse River is high, particularly for 

bedload sediment, considering the temporary impoundment 

of sediment stores in both basins by pro-glacial lakes. Significant morainal and tributary valley bottom sediment sources 

in the dynamically deglaciating headwaters of West Creek 

were partially released in the failure that generated the 2002 

glacial lake outburst flood but as of 2019, these sources were 

restricted from West Creek by a likely ephemeral pro-glacial 

lake.

Within the mapping area, the valley bottom is dominated 

by surfaces containing suites of abandoned main stem channels and the large, low-angle West Creek fan. Channels of the 

Taiya River have often been abandoned intact when the river 

moves, such that individual channels can retain their shape 

for many decades, providing a conduit for flowing water or a 

low point for ponding. A total of 29 off-main-stem channels 

were detected from slope derivatives of lidar elevation data 

and cataloged by origin. An inventory of water conditions and 

surface-water sources for these off-main-stem channels shows 

that except for the small networks of channels on the West 

Creek fan, water is generally present at some location within 

abandoned channels. Groundwater and small tributaries form 

important water sources for these wetland habitats. National 

Park Service (NPS) amphibian monitoring sites are located in 

wetlands fed mostly by groundwater but occasionally inundated by main stem flow. One successful toad breeding site 

occurs in a brackish environment that is occasionally tidally 

inundated.

The Taiya River is dynamically adjusting to valleyscale geomorphic processes and local controls. Within the 

main stem valley bottom, the Taiya River flow paths were 

consolidated between 1894 and 1948 to a single path little 

moved since 1948, and the active channel belt was narrowed 

within that path. Glacial lake outburst floods documented in 

the historical period and as recently as 2002 in West Creek 

form a discrete disturbance mechanism that locally affected 

vegetation and channel patterns but has not fully reset channel 

patterns since at least the Gold Rush. The effects of pre-Gold 

Rush glacial lake outburst floods could not be completely 

determined for this study, but geomorphic evidence indicates 

there was an association with a period of increased channel 

activity that left channel scars throughout the valley. At the 

reach scale within the mapping area, the river has responded to 

tributary inputs and has migrated or reworked channel patterns 

in several locations. Multiple channel changes at the West 

Creek confluence since 1894 without significant fan growth 

have been the primary direct influence of West Creek on Taiya 

River. The extent of the West Creek fan indicates a historical 

and modern constraint of the Taiya River position. The large 

contribution of West Creek streamflow to the Taiya River 

affects fluvial activity downstream, increasing the ability of 

the channel to migrate or rework channels. Smaller tributaryfed channels have locally modified their paths within larger 

abandoned channels and contribute flow critical to anadromous streams. Locally significant channel migration resulting 

in bank erosion within about 1 km downstream of West Creek 

and as much as 300 m of meander migration and erosion at the 

Dyea townsite since 1918 have occurred as episodic pulses, 

such that within a single season banks can migrate tens of 

meters, but periods of bank stability can persist for decades. 

Ephemeral to persistent large woody debris jams provide a 

local control on channel location and migration. Beaver dams 

have deflected flow and generated widespread flooded areas 

persistent at a decadal scale, including a series of ponds along 

the Chilkoot Trail.

Monitoring approaches that focus on identifying the 

relative importance of groundwater losses from West Creek 

and the Taiya River to wetland water sources could facilitate understanding the drivers of wetland hydrology. Further 

characterizing the water sources for wetland habitats, including tributaries, groundwater closely connected to main stem 

river cycles, and groundwater disconnected from main stem 

river cycles, would improve the understanding of the range of 

likely effects from changes to those water sources. Continued 

monitoring of bank erosion could be supplemented with aerial 

photograph analysis to track local bank change. Records from 

ongoing monitoring of streamflow and turbidity could be 

periodically examined to identify future changes associated 

with dynamic glacial conditions in the West Creek and Taiya 

River Basins.

The fluvial history of the Taiya River and the geomorphic processes and hydrology of the valley bottom provide 

a context and basis for approaching a range of KLGO management challenges, including constraints on and patterns of 

channel migration, sensitive recreational seasons, and formative processes of and water sources for off-main-stem wetland 

habitats. An understanding of the hydrologic dependence of 

park resources enables efficient park planning, monitoring, and 

response to natural or human-initiated changes in delivery of 

sediment and water.
54 Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska

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Appendix 1. Geographic Information System Digital Files 57

Appendix 1. Geographic Information System Digital Files

Digital files that accompany this report are available as a data release (Curran, 2020; https://doi.org/10.5066/P9XP1SE7). 

These include (1) polygons of geomorphic surfaces in the mapping area, (2) polygons of off-main-stem channels in the mapping 

area, and (3) metadata for the respective polygon files.

Publishing support provided by the U.S. Geological Survey

Science Publishing Network, Tacoma Publishing Service Center

For more information concerning the research in this report, contact the

Director, Alaska Science Center

U.S. Geological Survey

4210 University Drive

Anchorage, Alaska 99508

https://www.usgs.gov/centers/asc/
2 Report Title

Curran—Hydrology and Geomorphology of the Taiya River Near the West Creek Tributary, Southeast Alaska—Scientific Investigations Report 2020–5059

ISSN 2328-0328 (online)

https://doi.org/10.3133/sir20205059